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Sample records for aluminum oxide film

  1. Aluminum oxide film thickness and emittance

    SciTech Connect

    Thomas, J.K.; Ondrejcin, R.S.

    1991-11-01

    Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55{degrees}C) moderator for about a year. The average moderator temperature was assumed to be 30{degrees}C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 {mu}m {plus minus} 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 {mu}m {plus minus} 11%. Total hemispherical emittance is predicted to be 0.69 at 96{degrees}C, decreasing to 0.45 at 600{degrees}C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values.

  2. Aluminum oxide film thickness and emittance

    SciTech Connect

    Thomas, J.K.; Ondrejcin, R.S.

    1991-11-01

    Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55{degrees}C) moderator for about a year. The average moderator temperature was assumed to be 30{degrees}C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 {mu}m {plus_minus} 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 {mu}m {plus_minus} 11%. Total hemispherical emittance is predicted to be 0.69 at 96{degrees}C, decreasing to 0.45 at 600{degrees}C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values.

  3. The Effect of Anodic Oxide Films on the Nickel-Aluminum Reaction in Aluminum Braze Sheet

    NASA Astrophysics Data System (ADS)

    Tadgell, Colin A.; Wells, Mary A.; Corbin, Stephen F.; Colley, Leo; Cheadle, Brian; Winkler, Sooky

    2017-01-01

    The influence of an anodic oxide surface film on the nickel-aluminum reaction at the surface of aluminum brazing sheet has been investigated. Samples were anodized in a barrier-type solution and subsequently sputtered with nickel. Differential scanning calorimetry (DSC) and metallography were used as the main investigative techniques. The thickness of the anodic film was found to control the reaction between the aluminum substrate and nickel coating. Solid-state formation of nickel-aluminum intermetallic phases occurred readily when a relatively thin oxide film (13 to 25 nm) was present, whereas intermetallic formation was suppressed in the presence of thicker oxides ( 60 nm). At an intermediate oxide film thickness of 35 nm, the Al3Ni phase formed shortly after the initiation of melting in the aluminum substrate. Analysis of DSC traces showed that formation of nickel-aluminum intermetallic phases changed the melting characteristics of the aluminum substrate, and that the extent of this change can be used as an indirect measure of the amount of nickel incorporated into the intermetallic phases.

  4. The Effect of Anodic Oxide Films on the Nickel-Aluminum Reaction in Aluminum Braze Sheet

    NASA Astrophysics Data System (ADS)

    Tadgell, Colin A.; Wells, Mary A.; Corbin, Stephen F.; Colley, Leo; Cheadle, Brian; Winkler, Sooky

    2017-03-01

    The influence of an anodic oxide surface film on the nickel-aluminum reaction at the surface of aluminum brazing sheet has been investigated. Samples were anodized in a barrier-type solution and subsequently sputtered with nickel. Differential scanning calorimetry (DSC) and metallography were used as the main investigative techniques. The thickness of the anodic film was found to control the reaction between the aluminum substrate and nickel coating. Solid-state formation of nickel-aluminum intermetallic phases occurred readily when a relatively thin oxide film (13 to 25 nm) was present, whereas intermetallic formation was suppressed in the presence of thicker oxides ( 60 nm). At an intermediate oxide film thickness of 35 nm, the Al3Ni phase formed shortly after the initiation of melting in the aluminum substrate. Analysis of DSC traces showed that formation of nickel-aluminum intermetallic phases changed the melting characteristics of the aluminum substrate, and that the extent of this change can be used as an indirect measure of the amount of nickel incorporated into the intermetallic phases.

  5. Preparation of Aluminum Nanomesh Thin Films from an Anodic Aluminum Oxide Template as Transparent Conductive Electrodes.

    PubMed

    Li, Yiwen; Chen, Yulong; Qiu, Mingxia; Yu, Hongyu; Zhang, Xinhai; Sun, Xiao Wei; Chen, Rui

    2016-02-02

    We have employed anodic aluminum oxide as a template to prepare ultrathin, transparent, and conducting Al films with a unique nanomesh structure for transparent conductive electrodes. The anodic aluminum oxide template is obtained through direct anodization of a sputtered Al layer on a glass substrate, and subsequent wet etching creates the nanomesh metallic film. The optical and conductive properties are greatly influenced by experimental conditions. By tuning the anodizing time, transparent electrodes with appropriate optical transmittance and sheet resistance have been obtained. The results demonstrate that our proposed strategy can serve as a potential method to fabricate low-cost TCEs to replace conventional indium tin oxide materials.

  6. Preparation of Aluminum Nanomesh Thin Films from an Anodic Aluminum Oxide Template as Transparent Conductive Electrodes

    PubMed Central

    Li, Yiwen; Chen, Yulong; Qiu, Mingxia; Yu, Hongyu; Zhang, Xinhai; Sun, Xiao Wei; Chen, Rui

    2016-01-01

    We have employed anodic aluminum oxide as a template to prepare ultrathin, transparent, and conducting Al films with a unique nanomesh structure for transparent conductive electrodes. The anodic aluminum oxide template is obtained through direct anodization of a sputtered Al layer on a glass substrate, and subsequent wet etching creates the nanomesh metallic film. The optical and conductive properties are greatly influenced by experimental conditions. By tuning the anodizing time, transparent electrodes with appropriate optical transmittance and sheet resistance have been obtained. The results demonstrate that our proposed strategy can serve as a potential method to fabricate low-cost TCEs to replace conventional indium tin oxide materials. PMID:26831759

  7. Anodic Oxidation in Aluminum Electrode by Using Hydrated Amorphous Aluminum Oxide Film as Solid Electrolyte under High Electric Field.

    PubMed

    Yao, Manwen; Chen, Jianwen; Su, Zhen; Peng, Yong; Zou, Pei; Yao, Xi

    2016-05-04

    Dense and nonporous amorphous aluminum oxide (AmAO) film was deposited onto platinized silicon substrate by sol-gel and spin coating technology. The evaporated aluminum film was deposited onto the AmAO film as top electrode. The hydrated AmAO film was utilized as a solid electrolyte for anodic oxidation of the aluminum electrode (Al) film under high electric field. The hydrated AmAO film was a high efficiency electrolyte, where a 45 nm thick Al film was anodized completely on a 210 nm thick hydrated AmAO film. The current-voltage (I-V) characteristics and breakdown phenomena of a dry and hydrated 210 nm thick AmAO film with a 150 nm thick Al electrode pad were studied in this work. Breakdown voltage of the dry and hydrated 210 nm thick AmAO film were 85 ± 3 V (405 ± 14 MV m(-1)) and 160 ± 5 V (762 ± 24 MV m(-1)), respectively. The breakdown voltage of the hydrated AmAO film increased about twice, owing to the self-healing behavior (anodic oxidation reaction). As an intuitive phenomenon of the self-healing behavior, priority anodic oxidation phenomena was observed in a 210 nm thick hydrated AmAO film with a 65 nm thick Al electrode pad. The results suggested that self-healing behavior (anodic oxidation reaction) was occurring nearby the defect regions of the films during I-V test. It was an effective electrical self-healing method, which would be able to extend to many other simple and complex oxide dielectrics and various composite structures.

  8. Electrophoretic deposition of PTFE particles on porous anodic aluminum oxide film and its tribological properties

    NASA Astrophysics Data System (ADS)

    Zhang, Dongya; Dong, Guangneng; Chen, Yinjuan; Zeng, Qunfeng

    2014-01-01

    Polytetrafluoroethylene (PTFE) composite film was successfully fabricated by depositing PTFE particles into porous anodic aluminum oxide film using electrophoretic deposition (EPD) process. Firstly, porous anodic aluminum oxide film was synthesized by anodic oxidation process in sulphuric acid electrolyte. Then, PTFE particles in suspension were directionally deposited into the porous substrate. Finally, a heat treatment at 300 °C for 1 h was utilized to enhance PTFE particles adhesion to the substrate. The influence of anodic oxidation parameters on the morphology and micro-hardness of the porous anodic aluminum oxide film was studied and the PTFE particles deposited into the pores were authenticated using energy-dispersive spectrometer (EDS) and scanning electron microscopy (SEM). Tribological properties of the PTFE composite film were investigated under dry sliding. The experimental results showed that the composite film exhibit remarkable low friction. The composite film had friction coefficient of 0.20 which deposited in 15% PTFE emulsion at temperature of 15 °C and current density of 3 A/dm2 for 35 min. In addition, a control specimen of porous anodic aluminum oxide film and the PTFE composite film were carried out under the same test condition, friction coefficient of the PTFE composite film was reduced by 60% comparing with the control specimen at 380 MPa and 100 mm/s. The lubricating mechanism was that PTFE particles embedded in porous anodic aluminum oxide film smeared a transfer film on the sliding path and the micro-pores could support the supplement of solid lubricant during the sliding, which prolonged the lubrication life of the aluminum alloys.

  9. Surface enhanced Raman scattering of biospecies on anodized aluminum oxide films

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Smirnov, A. I.; Hahn, D.; Grebel, H.

    2007-06-01

    Traditionally, aluminum and anodized aluminum oxide films (AAO) are not the platforms of choice for surface-enhanced raman scattering (SERS) experiments despite of the aluminum's large negative permittivity value. Here we examine the usefulness of aluminum and nanoporous alumina platforms for detecting soft biospecies ranging from bacterial spores to protein markers. We used these flat platforms to examine SERS of a model protein (cytochrome c from bovine heart tissue) and bacterial cells (spores of Bacillus subtilis ATCC13933 used as Anthrax simulant) and demonstrated clear Raman amplification.

  10. Synthesis of nanoporous activated iridium oxide films by anodized aluminum oxide templated atomic layer deposition.

    SciTech Connect

    Comstock, D. J.; Christensen, S. T.; Elam, J. W.; Pellin, M. J.; Hersam, M. C.

    2010-08-01

    Iridium oxide (IrOx) has been widely studied due to its applications in electrochromic devices, pH sensing, and neural stimulation. Previous work has demonstrated that both Ir and IrOx films with porous morphologies prepared by sputtering exhibit significantly enhanced charge storage capacities. However, sputtering provides only limited control over film porosity. In this work, we demonstrate an alternative scheme for synthesizing nanoporous Ir and activated IrOx films (AIROFs). This scheme utilizes atomic layer deposition to deposit a thin conformal Ir film within a nanoporous anodized aluminum oxide template. The Ir film is then activated by potential cycling in 0.1 M H{sub 2}SO{sub 4} to form a nanoporous AIROF. The morphologies and electrochemical properties of the films are characterized by scanning electron microscopy and cyclic voltammetry, respectively. The resulting nanoporous AIROFs exhibit a nanoporous morphology and enhanced cathodal charge storage capacities as large as 311 mC/cm{sup 2}.

  11. High stability mechanisms of quinary indium gallium zinc aluminum oxide multicomponent oxide films and thin film transistors

    SciTech Connect

    Lee, Ching-Ting Lin, Yung-Hao; Lin, Jhong-Ham

    2015-01-28

    Quinary indium gallium zinc aluminum oxide (IGZAO) multicomponent oxide films were deposited using indium gallium zinc oxide (IGZO) target and Al target by radio frequency magnetron cosputtering system. An extra carrier transport pathway could be provided by the 3 s orbitals of Al cations to improve the electrical properties of the IGZO films, and the oxygen instability could be stabilized by the strong Al-O bonds in the IGZAO films. The electron concentration change and the electron mobility change of the IGZAO films for aging time of 10 days under an air environment at 40 °C and 75% humidity were 20.1% and 2.4%, respectively. The experimental results verified the performance stability of the IGZAO films. Compared with the thin film transistors (TFTs) using conventional IGZO channel layer, in conducting the stability of TFTs with IGZAO channel layer, the transconductance g{sub m} change, threshold voltage V{sub T} change, and the subthreshold swing S value change under the same aging condition were improved to 7.9%, 10.5%, and 14.8%, respectively. Furthermore, the stable performances of the IGZAO TFTs were also verified by the positive gate bias stress. In this research, the quinary IGZAO multicomponent oxide films and that applied in TFTs were the first studied in the literature.

  12. F2-Laser-Induced Modification of Aluminum Thin Films into Transparent Aluminum Oxide

    NASA Astrophysics Data System (ADS)

    Okoshi, Masayuki; Iwai, Kazufumi; Nojiri, Hidetoshi; Inoue, Narumi

    2012-12-01

    A vacuum-UV F2 laser of 157 nm wavelength induced strong oxidation of 10-nm-thick Al thin films, forming transparent Al2O3 on silica glass. The laser-induced modification occurred at the surface of Al thin films; consequently, the thickness of the formed Al2O3 thin films increased linearly with increasing number of F2 laser photons. The formation of equivalent-phase Al2O3 thin films was confirmed by X-ray photoelectron spectroscopy. The oxidation reaction in the laser-induced modification of 10-nm-thick Al thin films was slower than that for 20- and 60-nm-thick Al thin films. Morphological changes leading to the crystallization of the Al2O3 thin films were also observed when the thickness of Al thin films increased from 10 to 20 and 60 nm.

  13. Synthesis of iridescent Ni-containing anodic aluminum oxide films by anodization in oxalic acid

    NASA Astrophysics Data System (ADS)

    Xu, Qin; Ma, Hong-Mei; Zhang, Yan-Jun; Li, Ru-Song; Sun, Hui-Yuan

    2016-02-01

    Ni-containing anodic aluminum oxide films with highly saturated colors were synthesized using an ac electrodeposition method, and the optical and magnetic characteristics of the films were characterized. Precisely controllable color tuning could be obtained using wet-chemical etching to thin and widen the anodic aluminum oxide films pores isotropically before Ni deposition. Magnetic measurements indicate that such colored composite films not exhibit obvious easy magnetization direction. The resulted short (200 nm in length) and wide (50 nm in diameter) Ni nanowires present only fcc phase. The magnetization reversal mechanism is in good agreement with the symmetric fanning reversal mode which is discussed in detail. Such films may find applications in decoration, display and multifunctional anti-counterfeiting applications.

  14. Electromechanical Breakdown of Barrier-Type Anodized Aluminum Oxide Thin Films Under High Electric Field Conditions

    NASA Astrophysics Data System (ADS)

    Chen, Jianwen; Yao, Manwen; Yao, Xi

    2016-02-01

    Barrier-type anodized aluminum oxide (AAO) thin films were formed on a polished aluminum substrate via electrochemical anodization in 0.1 mol/L aqueous solution of ammonium pentaborate. Electromechanical breakdown occurred under high electric field conditions as a result of the accumulation of mechanical stress in the film-substrate system by subjecting it to rapid thermal treatment. Before the breakdown event, the electricity of the films was transported in a highly nonlinear way. Immediately after the breakdown event, dramatic cracking of the films occurred, and the cracks expanded quickly to form a mesh-like dendrite network. The breakdown strength was significantly reduced because of the electromechanical coupling effect, and was only 34% of the self-healing breakdown strength of the AAO film.

  15. Plasmonic nanodot array optimization on organic thin film solar cells using anodic aluminum oxide templates

    NASA Astrophysics Data System (ADS)

    Bae, Kyuyoung; Kim, Kyoungsik

    2013-09-01

    The fabrication method of plasmonic nanodots on ITO or nc-ZnO substrate has been developed to improve the efficiency of organic thin film solar cells. Nanoscale metallic nanodots arrays are fabricated by anodic aluminum oxide (AAO) template mask which can have different structural parameters by varying anodization conditions. In this paper, the structural parameters of metallic nanodots, which can be controlled by the diverse structures of AAO template mask, are investigated to enhance the optical properties of organic thin film solar cells. It is found that optical properties of the organic thin film solar cells are improved by finding optimization values of the structural parameters of the metallic nanodot array.

  16. Welding Phenomenon and Removal Mechanism of Aluminum-Oxide Films by Space GHTA Welding Process in Vacuum

    NASA Astrophysics Data System (ADS)

    Suita, Yoshikazu; Ekuni, Tomohide; Kamei, Misa; Tsukuda, Yoshiyuki; Terajima, Noboru; Yamashita, Masahiro; Imagawa, Kichiro; Masubuchi, Koichi

    Aluminum alloys have been widely used in constructing various space structures including the ISS (International Space Station) and launch vehicles. In order to apply the welding technology in space, welding experiments on aluminum alloy were performed using by the GHTA (Gas Hollow Tungsten Arc) welding processes using an inverter controlled DC/AC GTA welding machine in vacuum. We observed the removal mechanism of aluminum-oxide films on molten metal in detail during the welding using a high-speed video camera. As a result, it is clarified that the impact arc pressure produced by pulsed current mechanically crushes and removes aluminum-oxide films on the molten pool. This removal mechanism of aluminum-oxide films is completely different from a removal mechanism by cleaning action.

  17. Studies of aluminum oxide thin films deposited by laser ablation technique

    NASA Astrophysics Data System (ADS)

    Płóciennik, P.; Guichaoua, D.; Korcala, A.; Zawadzka, A.

    2016-06-01

    This paper presents the structural and optical investigations of the aluminum oxide nanocrystalline thin films. Investigated films were fabricated by laser ablation technique in high vacuum onto quartz substrates. The films were deposited at two different temperatures of the substrates equal to room temperature and 900 K. X-ray Diffraction spectra proved nanocrystalline character and the corundum phase of the film regardless on the substrate temperature during the deposition process. Values of the refractive indices, extinction and absorption coefficients were calculated by using Transmission and Reflection Spectroscopy in the UV-VIS-NIR range of the wavelength. Coupling Prism Method was used for films thickness estimations. Experimental measurements and theoretical calculations of the Third Harmonic Generation were also reported. Obtained results show that the lattice strain may affect obtained values of the third order nonlinear optical susceptibility.

  18. Rayleigh instability in polymer thin films coated in the nanopores of anodic aluminum oxide templates.

    PubMed

    Tsai, Chia-Chan; Chen, Jiun-Tai

    2014-01-14

    We study the Rayleigh instability of polystyrene (PS) thin films coated in the nanopores of anodic aluminum oxide (AAO) templates. After thermal annealing, the surface of the PS thin films undulates and the nanostructures transform from nanotubes to Rayleigh-instability-induced nanostructures (short nanorods with encapsulated air bubbles). With longer annealing times, the nanostructures further transform to nanorods with longer lengths. PS samples with two different molecular weights (24 and 100 kg/mol) are used, and their instability transformation processes are compared. The morphology diagrams of the nanostructures at different stages are also constructed to elucidate the mechanism of the morphology transformation.

  19. Dissolution of Oxide Films on Aluminum in Near Neutral Solutions

    SciTech Connect

    Isaacs, Hugh S.; Xu, Feng; Jeffcoate, Carrol S.

    1999-10-17

    Simple linear potentiodynamic cycling measurements have been made on abraded pure Al in borate, chromate, phosphate, sulfate and nitrate solutions. In borate and chromate solutions the currents continued to decrease with each subsequent cycle. In phosphate dissolution of the oxide takes place producing repetitive repeat curves. The current variations in borate and chromate were simulated using a high field conduction oxide growth model. Including oxide dissolution in the model simulated the phosphate behavior. Results in sulfate and nitrate solutions were more complex. The behavior in the sulfate solution was attributed to effects of sulfate the oxide/solution interface.

  20. Chemical Vapor Deposition of Aluminum Oxide Thin Films

    ERIC Educational Resources Information Center

    Vohs, Jason K.; Bentz, Amy; Eleamos, Krystal; Poole, John; Fahlman, Bradley D.

    2010-01-01

    Chemical vapor deposition (CVD) is a process routinely used to produce thin films of materials via decomposition of volatile precursor molecules. Unfortunately, the equipment required for a conventional CVD experiment is not practical or affordable for many undergraduate chemistry laboratories, especially at smaller institutions. In an effort to…

  1. Characterization of Monolayer Formation on Aluminum-Doped Zinc Oxide Thin Films

    SciTech Connect

    Rhodes,C.; Lappi, S.; Fischer, D.; Sambasivan, S.; Genzer, J.; Franzen, S.

    2008-01-01

    The optical and electronic properties of aluminum-doped zinc oxide (AZO) thin films on a glass substrate are investigated experimentally and theoretically. Optical studies with coupling in the Kretschmann configuration reveal an angle-dependent plasma frequency in the mid-IR for p-polarized radiation, suggestive of the detection of a Drude plasma frequency. These studies are complemented by oxygen depletion density functional theory studies for the calculation of the charge carrier concentration and plasma frequency for bulk AZO. In addition, we report on the optical and physical properties of thin film adlayers of n-hexadecanethiol (HDT) and n-octadecanethiol (ODT) self-assembled monolayers (SAMs) on AZO surfaces using reflectance FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Our characterization of the SAM deposition onto the AZO thin film reveals a range of possible applications for this conducting metal oxide.

  2. Mid-infrared optical properties of thin films of aluminum oxide, titanium dioxide, silicon dioxide, aluminum nitride, and silicon nitride.

    PubMed

    Kischkat, Jan; Peters, Sven; Gruska, Bernd; Semtsiv, Mykhaylo; Chashnikova, Mikaela; Klinkmüller, Matthias; Fedosenko, Oliana; Machulik, Stephan; Aleksandrova, Anna; Monastyrskyi, Gregorii; Flores, Yuri; Masselink, W Ted

    2012-10-01

    The complex refractive index components, n and k, have been studied for thin films of several common dielectric materials with a low to medium refractive index as functions of wavelength and stoichiometry for mid-infrared (MIR) wavelengths within the range 1.54-14.29 μm (700-6500 cm(-1)). The materials silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, and titanium oxide are prepared using room temperature reactive sputter deposition and are characterized using MIR variable angle spectroscopic ellipsometry. The investigation shows how sensitive the refractive index functions are to the O2 and N2 flow rates, and for which growth conditions the materials deposit homogeneously. It also allows conclusions to be drawn on the degree of amorphousness and roughness. To facilitate comparison of the materials deposited in this work with others, the index of refraction was also determined and provided for the near-IR and visible ranges of the spectrum. The results presented here should serve as a useful information base for designing optical coatings for the MIR part of the electromagnetic spectrum. The results are parameterized to allow them to be easily used for coating design.

  3. Advantages of Oxide Films as Bases for Aluminum Pigmented Surface Coatings for Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Buzzard, R W; Mutchler, W H

    1931-01-01

    Both laboratory and weather-exposure corrosion tests showed conclusively that the protection afforded by aluminum pigmented spar varnish coatings applied to previously anodized aluminum surfaces was greatly superior to that afforded by the same coatings applied to surfaces which had simply been cleaned free from grease and not anodized.

  4. Adhesion of Poly(phenylene sulfide) Resin with Polymeric Film of Triazine Thiol on Aluminum Surface Modified by Anodic Oxidation.

    PubMed

    Chung, Eun Hyuk; Jang, Eun Kyung; Hong, Tae Eun; Kim, Jong Pil; Kim, Hyun Gyu; Jin, Jong Sung; Hyun, Myung Ho; Shin, Dong Su; Bae, Jong-Seong; Jeong, Euh Duck

    2015-01-01

    Various surface modifications have been applied to improve the adhesion properties of aluminum for the cap plate and sealing quality of electrolyte on Li ion batteries. In this study, we have tried to find the effective condition for the polymerization of triazine thiols (TT) on modified aluminum surfaces by anodic aluminum oxide. Characterization of polymerized films on aluminum was explored by scanning electron microscopy, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy analysis. Scanning electron microscopy results reveal that meaningful roughness was formed on aluminum surfaces by anodic oxidation. Secondary ion mass spectroscopy analysis results represent that the peel strength was found to depend on film thickness and the composition of the adhesion layer. As a result, Al/PPS (polyphenylene sulfide) resin assemblies developed in this study have superior adhesive property. Therefore, these assemblies might be a viable candidate for a sealing technique for Li ion batteries.

  5. Structural and optical properties of DC reactive magnetron sputtered zinc aluminum oxide thin films

    SciTech Connect

    Kumar, B. Rajesh; Rao, T. Subba

    2014-10-15

    Highly transparent conductive Zinc Aluminum Oxide (ZAO) thin films have been deposited on glass substrates using DC reactive magnetron sputtering method. The thin films were deposited at 200 °C and post-deposition annealing from 15 to 90 min. XRD patterns of ZAO films exhibit only (0 0 2) diffraction peak, indicating that they have c-axis preferred orientation perpendicular to the substrate. Scanning electron microscopy (SEM) is used to study the surface morphology of the films. The grain size obtained from SEM images of ZAO thin films are found to be in the range of 20 - 26 nm. The minimum resistivity of 1.74 × 10{sup −4} Ω cm and an average transmittance of 92% are obtained for the thin film post annealed for 30 min. The optical band gap of ZAO thin films increased from 3.49 to 3.60 eV with the increase of annealing time due to Burstein-Moss effect. The optical constants refractive index (n) and extinction coefficient (k) were also determined from the optical transmission spectra.

  6. Reactively Deposited Aluminum Oxide and Fluoropolymer Filled Aluminum Oxide Protective Coatings for Polymers

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.; Banks, Bruce A.; Hunt, Jason

    1995-01-01

    Reactive ion beam sputter deposition of aluminum simultaneous with low energy arrival of oxygen ions at the deposition surface enables the formation of highly transparent aluminum oxide films. Thick (12 200 A), adherent, low stress, reactively deposited aluminum oxide films were found to provide some abrasion resistance to polycarbonate substrates. The reactively deposited aluminum oxide films are also slightly more hydrophobic and more transmitting in the UV than aluminum oxide deposited from an aluminum oxide target. Simultaneous reactive sputter deposition of aluminum along with polytetrafluoroethylene (PTFE Teflon) produces fluoropolymer-filled aluminum oxide films which are lower in stress, about the same in transmittance, but more wetting than reactively deposited aluminum oxide films. Deposition properties, processes and potential applications for these coatings will be discussed.

  7. Stability of Indium Gallium Zinc Aluminum Oxide Thin-Film Transistors with Treatment Processes

    NASA Astrophysics Data System (ADS)

    Lin, Yung-Hao; Lee, Ching-Ting

    2017-02-01

    The indium-gallium-zinc-aluminum-oxide (IGZAO) channel layer of the bottom-gate-type thin-film transistors (TFTs) was deposited on indium tin oxide-coated glass substrates using a magnetron radio frequency co-sputtering system with dual targets of indium gallium zinc oxide and Al. The 3 s orbital of Al cations provided an extra transport pathway and widened the bottom of the conduction band, thus increasing the electron mobility in the IGZAO films. The Al-O bonds could sustain the stability of oxygen of the IGZAO films. The IGZAO TFTs were processed by O2 plasma and post-annealing treatments. Hysteresis analysis was carried out in order to study the stability of the resulting IGZAO TFTs, the positive bias temperature stress (PBTS) performance, and the hot carrier effect were also measured. For the IGZAO TFTs, the threshold voltage shift of the PBTS performance and the hot carrier effect were 0.1 V and 0.06 V, respectively. Overall, the IGZAO TFTs exhibited good stability in this study.

  8. Anodic Oxide Films on Aluminum: Their Significance for Corrosion Protection and Micro- and Nano-Technologies

    NASA Astrophysics Data System (ADS)

    Takahashi, Hideaki; Sakairi, Masatoshi; Kikuchi, Tatsuya

    It was only 120 years ago that humans became able to obtain aluminum metal industrially by applying electricity to reduce bauxite ore. Hence, aluminum is much newer than other metals such as copper, iron, and gold, which have been used since pre-historical times. This is surprising since aluminum comprises 7.56 % of all elements near the surface of the earth, and is found in abundant amounts, next to only oxygen and silicon. The reason why aluminum metal only became available fairly recently is that aluminum has a strong chemical affinity to oxygen, and this prevents reduction of aluminum oxide by chemical reaction with carbon at high temperatures, unlike iron- and copper-oxides. Reduction of aluminum oxide was first realized by H. Davy in 1807, using Voltaic piles, which had been invented in 1800 by the Italian scientist, A. Volta.

  9. Hydrogen plasma treatment for improved conductivity in amorphous aluminum doped zinc tin oxide thin films

    SciTech Connect

    Morales-Masis, M. Ding, L.; Dauzou, F.; Jeangros, Q.; Hessler-Wyser, A.; Nicolay, S.; Ballif, C.

    2014-09-01

    Improving the conductivity of earth-abundant transparent conductive oxides (TCOs) remains an important challenge that will facilitate the replacement of indium-based TCOs. Here, we show that a hydrogen (H{sub 2})-plasma post-deposition treatment improves the conductivity of amorphous aluminum-doped zinc tin oxide while retaining its low optical absorption. We found that the H{sub 2}-plasma treatment performed at a substrate temperature of 50 °C reduces the resistivity of the films by 57% and increases the absorptance by only 2%. Additionally, the low substrate temperature delays the known formation of tin particles with the plasma and it allows the application of the process to temperature-sensitive substrates.

  10. The roles of the surface oxide film and metal-oxide interfacial defects in corrosion initiation on aluminum

    NASA Astrophysics Data System (ADS)

    Wu, Huiquan

    In the first part, a mathematical model was developed for oxide thickness and faradaic current, assuming high-field conduction and a uniform oxide layer thickness, and incorporating as input the measured potential. Electrochemical current and potential transients were measured during anodic oxidation of aluminum. The ratio of the experimental faradaic current density to the predicted one using high field model, p, was calculated. The measured faradaic current is about 104 times smaller than that predicted by this model initially, but the two converge after the initial period of time when p approaches 1. This discrepancy may be caused by several reasons. Our nonuniform oxide thickness hypothesis was supported by: similar p˜x characteristics for the same film obtained from different polarization experiments, where x is the solid-state barrier layer thickness of the oxide film; model's capability of predicting film structure change due to pretreatment such as NaOH dissolution, H2SO4 immersion, and electropolishing; the capacity of predicting long-time current decays using high field model; the lower anodic current of the foils subjected a short anodic pulse previously. In the second part, the effect of H3PO4 immersion on pit nucleation on aluminum during anodic etching in hot HCl solution was investigated. It was found that the phosphoric acid immersion dramatically enhances the susceptibility of aluminum foil to anodic pitting corrosion, and the trend of the pit number density with the immersion time corresponds to decrease of surface oxide film thickness. AFM observation of the topography of foils which were experienced phosphoric acid treatment followed by oxide stripping in chromic-phosphoric acid solution revealed presence of cavities. PAS measurements show the existence of interfacial voids of nm dimensions, whose metallic surface is oxide-free. These defects can be introduced by electropolishing and H3PO4 immersion. The strong similarity between the surface

  11. Optical properties of one-dimensional photonic crystals based on porous films of anodic aluminum oxide

    NASA Astrophysics Data System (ADS)

    Gorelik, V. S.; Klimonsky, S. O.; Filatov, V. V.; Napolskii, K. S.

    2016-04-01

    The optical properties of one-dimensional photonic crystals based on porous anodic aluminum oxide films have been studied by measuring transmittance and specular reflectance spectra in the visible and UV spectral regions. Angular dependences of the spectral positions of optical stop bands are obtained. It is shown that the reflectance within the first stop band varies from point to point on the sample surface, reaching a level of 98-99% at some points. The dispersion relation for electromagnetic waves in the model of infinite periodic structure is calculated for the samples under study. The possibility of using models with an infinite or finite number of layers to calculate reflectance spectra near the first optical stop band is discussed.

  12. Atomic layer deposited lithium aluminum oxide: (In)dependency of film properties from pulsing sequence

    SciTech Connect

    Miikkulainen, Ville Nilsen, Ola; Fjellvåg, Helmer; Li, Han; King, Sean W.; Laitinen, Mikko; Sajavaara, Timo

    2015-01-01

    Atomic layer deposition (ALD) holds markedly high potential of becoming the enabling method for achieving the three-dimensional all-solid-state thin-film lithium ion battery (LiB). One of the most crucial components in such a battery is the electrolyte that needs to hold both low electronic conductivity and at least fair lithium ion conductivity being at the same time pinhole free. To obtain these desired properties in an electrolyte film, one necessarily has to have a good control over the elemental composition of the deposited material. The present study reports on the properties of ALD lithium aluminum oxide (Li{sub x}Al{sub y}O{sub z}) thin films. In addition to LiB electrolyte applications, Li{sub x}Al{sub y}O{sub z} is also a candidate low dielectric constant (low-k) etch stop and diffusion barrier material in nanoelectronics applications. The Li{sub x}Al{sub y}O{sub z} films were deposited employing trimethylaluminum-O{sub 3} and lithium tert-butoxide-H{sub 2}O for Al{sub 2}O{sub 3} and Li{sub 2}O/LiOH, respectively. The composition was aimed to be controlled by varying the pulsing ratio of those two binary oxide ALD cycles. The films were characterized by several methods for composition, crystallinity and phase, electrical properties, hardness, porosity, and chemical environment. Regardless of the applied pulsing ratio of Al{sub 2}O{sub 3} and Li{sub 2}O/LiOH, all the studied ALD Li{sub x}Al{sub y}O{sub z} films of 200 and 400 nm in thickness were polycrystalline in the orthorhombic β-LiAlO{sub 2} phase and also very similar to each other with respect to composition and other studied properties. The results are discussed in the context of both fundamental ALD chemistry and applicability of the films as thin-film LiB electrolytes and low-k etch stop and diffusion barriers.

  13. Plasmon-induced optical switching of electrical conductivity in porous anodic aluminum oxide films encapsulated with silver nanoparticle arrays.

    PubMed

    Huang, Chen-Han; Lin, Hsing-Ying; Lau, Ben-Chao; Liu, Chih-Yi; Chui, Hsiang-Chen; Tzeng, Yonhua

    2010-12-20

    We report on plasmon induced optical switching of electrical conductivity in two-dimensional (2D) arrays of silver (Ag) nanoparticles encapsulated inside nanochannels of porous anodic aluminum oxide (AAO) films. The reversible switching of photoconductivity greatly enhanced by an array of closely spaced Ag nanoparticles which are isolated from each other and from the ambient by thin aluminum oxide barrier layers are attributed to the improved electron transport due to the localized surface plasmon resonance and coupling among Ag nanoparticles. The photoconductivity is proportional to the power, and strongly dependent on the wavelength of light illumination. With Ag nanoparticles being isolated from the ambient environments by a thin layer of aluminum oxide barrier layer of controlled thickness in nanometers to tens of nanometers, deterioration of silver nanoparticles caused by environments is minimized. The electrochemically fabricated nanostructured Ag/AAO is inexpensive and promising for applications to integrated plasmonic circuits and sensors.

  14. Tensile strain effect in ferroelectric perovskite oxide thin films on spinel magnesium aluminum oxide substrate

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaolan

    Ferroelectrics are used in FeRAM (Ferroelectric random-access memory). Currently (Pb,Zr)TiO3 is the most common ferroelectric material. To get lead-free and high performance ferroelectric material, we investigated perovskite ferroelectric oxides (Ba,Sr)TiO3 and BiFeO3 films with strain. Compressive strain has been investigated intensively, but the effects of tensile strain on the perovskite films have yet to be explored. We have deposited (Ba,Sr)TiO3, BiFeO3 and related films by pulsed laser deposition (PLD) and analyzed the films by X-ray diffractometry (XRD), atomic force microscopy (AFM), etc. To obtain inherently fully strained films, the selection of the appropriate substrates is crucial. MgAl2O4 matches best with good quality and size, yet the spinel structure has an intrinsic incompatibility to that of perovskite. We introduced a rock-salt structure material (Ni 1-xAlxO1+delta) as a buffer layer to mediate the structural mismatch for (Ba,Sr)TiO3 films. With buffer layer Ni1-xAlxO1+delta, we show that the BST films have high quality crystallization and are coherently epitaxial. AFM images show that the films have smoother surfaces when including the buffer layer, indicating an inherent compatibility between BST-NAO and NAO-MAO. In-plane Ferroelectricity measurement shows double hysteresis loops, indicating an antiferroelectric-like behavior: pinned ferroelectric domains with antiparallel alignments of polarization. The Curie temperatures of the coherent fully strained BST films are also measured. It is higher than 900°C, at least 800°C higher than that of bulk. The improved Curie temperature makes the use of BST as FeRAM feasible. We found that the special behaviors of ferroelectricity including hysteresis loop and Curie temperature are due to inherent fully tensile strain. This might be a clue of physics inside ferroelectric stain engineering. An out-of-plane ferroelectricity measurement would provide a full whole story of the tensile strain. However, a

  15. Tuning the composition and nanostructure of Pt/Ir films via anodized aluminum oxide templated atomic layer deposition.

    SciTech Connect

    Comstock, D. J.; Christensen, S. T.; Elam, J. W.; Pellin, M. J.; Hersam, M. C.; Northwestern Univ.

    2010-09-23

    Nanostructured metal films have been widely studied for their roles in sensing, catalysis, and energy storage. In this work, the synthesis of compositionally controlled and nanostructured Pt/Ir films by atomic layer deposition (ALD) into porous anodized aluminum oxide templates is demonstrated. Templated ALD provides advantages over alternative synthesis techniques, including improved film uniformity and conformality as well as atomic-scale control over morphology and composition. Nanostructured Pt ALD films are demonstrated with morphological control provided by the Pt precursor exposure time and the number of ALD cycles. With these approaches, Pt films with enhanced surface areas, as characterized by roughness factors as large as 310, are reproducibly synthesized. Additionally, nanostructured Ptlr alloy films of controlled composition and morphology are demonstrated by templated ALD, with compositions varying systematically from pure Pt to pure Ir. Lastly, the application of nanostructured Pt films to electrochemical sensing applications is demonstrated by the non-enzymatic sensing of glucose.

  16. Comparative study of structure and permeability of porous oxide films on aluminum obtained by single- and two-step anodization.

    PubMed

    Petukhov, Dmitrii I; Napolskii, Kirill S; Berekchiyan, Mikhail V; Lebedev, Alexander G; Eliseev, Andrey A

    2013-08-28

    A comparative study of the structure and transport properties of porous aluminum oxide films obtained by single- and two-step anodization was carried out. It is shown that the oxidation regime significantly affect the number of dead-ended channels, which results in more than twice the variation in membrane permeability. The effect is explained by multiple branching of channels on the initial stages of organization of the porous structure. Branching also occurs on later stages governing mass transport properties of porous anodic alumina films. A model describing transport properties of anodic aluminum oxide membranes based on pore branching on domain boundaries was suggested to fit experimental results of permeance of membranes obtained by both single- and two-step anodization.

  17. Influence of the surface pre-treatment of aluminum on the processes of formation of cerium oxides protective films

    NASA Astrophysics Data System (ADS)

    Andreeva, R.; Stoyanova, E.; Tsanev, A.; Stoychev, D.

    2016-03-01

    It is known that there is special interest in the contemporary investigations on conversion treatment of aluminum aimed at promoting its corrosion stability, which is focused on electrolytes on the basis of salts of metals belonging to the group of rare-earth elements. Their application is especially attractive, as it enables a successful substitution of the presently applied highly efficient, but at the same time toxic Cr6+-containing electrolytes. The present paper presents a study on the influence of the preliminary alkaline activation and acidic de-oxidation of the aluminum surface on the processes of immersion formation of protective cerium oxides films on Al 1050. The results obtained show that their deposition from simple electrolytes (containing only salts of Ce3+ ions) on the Al surface, treated only in alkaline solution, occurs at a higher rate, which leads to preparing thicker oxide films having a better protective ability. In the cases when the formation of oxide films is realized in a complex electrolyte (containing salts of Ce3+ and Cu2+ ions), better results are obtained with respect to the morphology and protective action of cerium oxides film on samples that have been consecutively activated in alkaline solution and deoxidized in acidic solution. Electrochemical investigations were carried out in a model corrosion medium (0.1 M NaCl); it was shown that the cerium protective films, deposited by immersion, have a cathodic character with regard to the aluminum support and inhibit the occurrence of the depolarizing corrosion process -- the reaction of oxygen reduction.

  18. Electrical and Optical Properties of Hydrogen Doped Aluminum-Doped Zinc Oxide Thin Films for Low Cost Applications.

    PubMed

    Park, Yong Seob; Park, Young; Kwon, Samyoung; Kim, Eung Kwon; Choi, Wonseok; Kim, Donguk; Kim, Minha; Lee, Jaehyeong

    2016-05-01

    Aluminum-doped zinc oxide (AZO) thin films were prepared on glass substrate using a magnetron sputtering system. In this work, a powder target was used as a source material for low cost applications, instead of a conventional sintered ceramic target. The effects of the hydrogen gas ratio on the electrical and optical properties of the AZO films. The hydrogen doped AZO (AZO:H) films had a hexagonal polycrystalline structure. A small amount of hydrogen gas deteriorated the electrical and optical properties of the AZO:H films. However, these properties improved, as the H2/(H2 + Ar) gas ratio increased. The AZO:H films grown at an H2/(H2+Ar) ratio of 10% showed good properties for low cost applications, such as a low resistivity of 1.35 x 10(-3) Ω-cm, high average transmittance of 83.1% in the visible range of light.

  19. Preparation of Hard Oxide Films on Evaporated Aluminum Surfaces and Applications of Such Films

    DTIC Science & Technology

    1949-07-28

    Anodic coatings produced with various voltages (10 to 150 voltsT were released from their substrate by dissolving the aluminum in a solution of mercuric ...from its substrate in mercuric chloride, washed with dilute hydrochloric acid and distilled water, and mounted on a support screen for the electron...thallium halides and other snythetic And study of methods of shaping, grinding, and polishing ,fi such crystals, A ;l .ication of low reflectance coatings

  20. Tailoring the refractive index of aluminum doped zinc oxide thin films by co-doping with titanium

    NASA Astrophysics Data System (ADS)

    Wei, Tiefeng; Lan, Pinjun; Yang, Ye; Zhang, Xianpeng; Tan, Ruiqin; Li, Yong; Song, Weijie

    2012-12-01

    The refractive index of transparent conductive oxides has a direct effect on the transmission of lights into thin film solar cells. Here we report the study of improving the refractive index of aluminum doped zinc oxide through titanium co-doping. The Al-Ti co-doped zinc oxide (ATZO) thin films with different Ti doping concentration were deposited on glass substrates by radio frequency magnetron sputtering with ATZO targets in an argon atmosphere. The structural, optical and electrical properties of the thin films were investigated using X-ray diffraction, ultraviolet-visible-near-infrared spectroscopy and hall measurements, respectively. The results showed that the as-deposited thin films were all textured along c-axis and perpendicular to the surface of substrate. The average transmittance in the visible region were more than 80% for all the ATZO thin films. The minimum resistivity of the obtained ATZO (1 wt% TiO2 doping) thin films were 2.6 × 10-3 Ω cm and 1.4 × 10-3 Ω cm before and after annealing in vacuum, respectively. The refractive index of the thin films (at λ0 = 550 nm) increased from 1.91 to 2.05 as the TiO2 content increased from 0 wt% to 3 wt%.

  1. Post-annealed gallium and aluminum co-doped zinc oxide films applied in organic photovoltaic devices

    PubMed Central

    2014-01-01

    Gallium and aluminum co-doped zinc oxide (GAZO) films were produced by magnetron sputtering. The GAZO films were post-annealed in either vacuum or hydrogen microwave plasma. Vacuum- and hydrogen microwave plasma-annealed GAZO films show different surface morphologies and lattice structures. The surface roughness and the spacing between adjacent (002) planes decrease; grain growth occurs for the GAZO films after vacuum annealing. The surface roughness increases and nanocrystals are grown for the GAZO films after hydrogen microwave plasma annealing. Both vacuum and hydrogen microwave plasma annealing can improve the electrical and optical properties of GAZO films. Hydrogen microwave plasma annealing improves more than vacuum annealing does for GAZO films. An electrical resistivity of 4.7 × 10−4 Ω-cm and average optical transmittance in the visible range from 400 to 800 nm of 95% can be obtained for the GAZO films after hydrogen microwave plasma annealing. Hybrid organic photovoltaic (OPV) devices were fabricated on the as-deposited, vacuum-annealed, and hydrogen microwave plasma-annealed GAZO-coated glass substrates. The active layer consisted of blended poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) in the OPV devices. The power conversion efficiency of the OPV devices is 1.22% for the hydrogen microwave plasma-annealed GAZO films, which is nearly two times higher compared with that for the as-deposited GAZO films. PMID:25352768

  2. Observation of isolated nanopores formed by patterned anodic oxidation of aluminum thin films

    SciTech Connect

    Huang Qiyu; Lye, W.-K.; Reed, Michael L.

    2006-06-05

    We report the formation of confined nanometer-scale regions of porous anodic alumina from thin aluminum films. Confinement is achieved by masking a thin Al film with a sputtered SiO{sub 2} layer, patterned by nanoimprint lithography of a polystyrene transfer layer. Anodization in 0.3 molar oxalic acid creates vertically aligned pores that were imaged with a combination of focused ion beam milling and scanning electron microscopy. Triplets, pairs, and single pores were observed following the anodization of isolated mask features approximately 100 nm in diameter.

  3. Different properties of aluminum doped zinc oxide nanostructured thin films prepared by radio frequency magnetron sputtering

    SciTech Connect

    Bidmeshkipour, Samina Shahtahmasebi, Nasser

    2013-06-15

    Aluminium doped zinc oxide (AZO) nanostructured thin films are prepared by radio frequency magnetron sputtering on glass substrate using specifically designed ZnO target containing different amount of Al{sub 2}O{sub 3} powder as the Al doping source. The optical properties of the aluminium doped zinc oxide films are investigated. The topography of the deposited films were investigated by Atomic Force Microscopy. Variation of the refractive index by annealing temperature are considered and it is seen that the refractive index increases by increasing the annealing temperature.

  4. Facile and environmentally friendly solution-processed aluminum oxide dielectric for low-temperature, high-performance oxide thin-film transistors.

    PubMed

    Xu, Wangying; Wang, Han; Xie, Fangyan; Chen, Jian; Cao, Hongtao; Xu, Jian-Bin

    2015-03-18

    We developed a facile and environmentally friendly solution-processed method for aluminum oxide (AlOx) dielectrics. The formation and properties of AlOx thin films under various annealing temperatures were intensively investigated by thermogravimetric analysis-differential scanning calorimetry (TGA-DSC), X-ray diffraction (XRD), spectroscopic ellipsometry, atomic force microscopy (AFM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), impedance spectroscopy, and leakage current measurements. The sol-gel-derived AlOx thin film undergoes the decomposition of organic residuals and nitrate groups, as well as conversion of aluminum hydroxides to form aluminum oxide, as the annealing temperature increases. Finally, the AlOx film is used as gate dielectric for a variety of low-temperature solution-processed oxide TFTs. Above all, the In2O3 and InZnO TFTs exhibited high average mobilities of 57.2 cm(2) V(-1) s(-1) and 10.1 cm(2) V(-1) s(-1), as well as an on/off current ratio of ∼10(5) and low operating voltages of 4 V at a maximum processing temperature of 300 °C. Therefore, the solution-processable AlOx could be a promising candidate dielectric for low-cost, low-temperature, and high-performance oxide electronics.

  5. MTBE OXIDATION BY BIFUNCTIONAL ALUMINUM

    EPA Science Inventory

    Bifunctional aluminum, prepared by sulfating zero-valent aluminum with sulfuric acid, has a dual functionality of simultaneously decomposing both reductively- and oxidatively-degradable contaminants. In this work, the use of bifunctional aluminum for the degradation of methyl te...

  6. A study of the protective properties of oxide films formed at reactive aluminum-copper and aluminum-beryllium alloys

    NASA Astrophysics Data System (ADS)

    Potucek, Rudolf Karel

    Two Al alloys of interest to the aerospace industry were studied during this research. AA2219 is an Al/Cu alloy containing about 6%-wt Cu, forming Cu-rich particles in a Cu-poor Al-matrix. AlBeMet162 is an At/Be alloy consisting of ca. 38%-wt A1 and 62%-wt Be, forming intermeshed networks of Al and Be. Both alloys do not respond to standard anodization techniques in sulfuric or chromic acid, yielding pitted surfaces and friable anodic coatings. Corrosion protection can be achieved on AA2219 but a significant part of its fatigue strength will be sacrificed as a result of these anodization processes, while no corrosion protection results from the anodization of AIBeMetl62. Thus, the main goals of this work were preventing the dissolution of the more reactive alloy constituents and electrochemical formation of a passivating surface coating. Cyclic Voltammetry methods (CV) were used as a means of creating barrier and porous oxide layers on AA2219, AlBeMet162 and the individual phases making up these alloys. The CV data and measurements of Electrochemical Impedance Spectroscopy (EIS) were used to determine the thickness and dissolution activity of the barrier oxide layers formed. Changes in the barrier oxide thickness during EIS and CV experiments in neutral borate and phosphate buffer as well as H2SO4 and H3PO4 solutions provided a means for predicting whether a stable barrier or porous oxide film would likely be formed in a given electrolyte. This approach was shown to be usable even in the presence of an overlying porous oxide film. The CV data were also examined for an indication of the oxide growth mechanism, with a particular focus on the High Field and Point Defect models, indicating that the High Field Model more closely fits the data acquired. EIS data collected in 5%-wt NaCl solution were shown to give a good indication of the corrosion protection granted by anodic coatings formed on A1 alloys and thus to be a suitable method for accelerated corrosion testing

  7. Sol-gel deposited aluminum-doped and gallium-doped zinc oxide thin-film transparent conductive electrodes with a protective coating of reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Zhu, Zhaozhao; Mankowski, Trent; Balakrishnan, Kaushik; Shikoh, Ali Sehpar; Touati, Farid; Benammar, Mohieddine A.; Mansuripur, Masud; Falco, Charles M.

    2016-04-01

    Using a traditional sol-gel deposition technique, we successfully fabricated aluminum-doped zinc oxide (AZO) and gallium-doped zinc oxide (GZO) thin films on glass substrates. Employing a plasma treatment method as the postannealing process, we produced thin-film transparent conductive electrodes exhibiting excellent optical and electrical properties, with transmittance greater than 90% across the entire visible spectrum and the near-infrared range, as well as good sheet resistance under 200 Ω/sq. More importantly, to improve the resilience of our fabricated thin-film samples at elevated temperatures and in humid environments, we deposited a layer of reduced graphene oxide (rGO) as protective overcoating. The stability of our composite AZO/rGO and GZO/rGO samples improved substantially compared to that of their counterparts with no rGO coating.

  8. The impact of thickness and thermal annealing on refractive index for aluminum oxide thin films deposited by atomic layer deposition.

    PubMed

    Wang, Zi-Yi; Zhang, Rong-Jun; Lu, Hong-Liang; Chen, Xin; Sun, Yan; Zhang, Yun; Wei, Yan-Feng; Xu, Ji-Ping; Wang, Song-You; Zheng, Yu-Xiang; Chen, Liang-Yao

    2015-01-01

    The aluminum oxide (Al2O3) thin films with various thicknesses under 50 nm were deposited by atomic layer deposition (ALD) on silicon substrate. The surface topography investigated by atomic force microscopy (AFM) revealed that the samples were smooth and crack-free. The ellipsometric spectra of Al2O3 thin films were measured and analyzed before and after annealing in nitrogen condition in the wavelength range from 250 to 1,000 nm, respectively. The refractive index of Al2O3 thin films was described by Cauchy model and the ellipsometric spectra data were fitted to a five-medium model consisting of Si substrate/SiO2 layer/Al2O3 layer/surface roughness/air ambient structure. It is found that the refractive index of Al2O3 thin films decrease with increasing film thickness and the changing trend revised after annealing. The phenomenon is believed to arise from the mechanical stress in ALD-Al2O3 thin films. A thickness transition is also found by transmission electron microscopy (TEM) and SE after 900°C annealing.

  9. Effect of Sputtering Gas environments on the Properties of Aluminum-doped Zinc Oxide Thin Films for Photovoltaic Application

    SciTech Connect

    Chauhan, Ram Narayan; Kumar, Jitendra; Singh, C.; Anand, R. S.

    2011-10-20

    Aluminum-doped zinc oxide thin films have been deposited on glass substrates by R.F. sputtering using ZnO(98%)-Al{sub 2}O{sub 3}(2%) target in different sputtering gaseous environments, viz., Ar, Ar/O{sub 2} and Ar/N{sub 2}+H{sub 2} at 80 deg. C. These films have been studied with regard to phase, microstructure, optical absorption and sheet resistance for application in photovoltaic devices as transparent conducting electrodes. The properties of the films are shown to strongly depend on the sputtering gas(es). The films exhibit a wurtzite-type hexagonal structure with the (00.2) preferred orientation, the c-axis perpendicular to the substrate. The intensity of 00.2 diffraction peak and the average crystallite size remain almost the same when the films are prepared under pure Ar or Ar/O{sub 2} environment. However the average crystallite size increases while electrical resistance decreases with introduction of nitrogen and hydrogen in comparison to oxygen in argon. Nevertheless, the optimum value of optical transmittance and sheet resistance of the films deposited in pure argon are found to be 85-96% in the wavelength range 400-800 nm and 65 {Omega}/{open_square}, respectively.

  10. Aqueous combustion synthesis of aluminum oxide thin films and application as gate dielectric in GZTO solution-based TFTs.

    PubMed

    Branquinho, Rita; Salgueiro, Daniela; Santos, Lídia; Barquinha, Pedro; Pereira, Luís; Martins, Rodrigo; Fortunato, Elvira

    2014-11-26

    Solution processing has been recently considered as an option when trying to reduce the costs associated with deposition under vacuum. In this context, most of the research efforts have been centered in the development of the semiconductors processes nevertheless the development of the most suitable dielectrics for oxide based transistors is as relevant as the semiconductor layer itself. In this work we explore the solution combustion synthesis and report on a completely new and green route for the preparation of amorphous aluminum oxide thin films; introducing water as solvent. Optimized dielectric layers were obtained for a water based precursor solution with 0.1 M concentration and demonstrated high capacitance, 625 nF cm(-2) at 10 kHz, and a permittivity of 7.1. These thin films were successfully applied as gate dielectric in solution processed gallium-zinc-tin oxide (GZTO) thin film transistors (TFTs) yielding good electrical performance such as subthreshold slope of about 0.3 V dec(-1) and mobility above 1.3 cm2 V(-1) s(-1).

  11. Ultrafast carrier dynamics and third order nonlinear optical properties of aluminum doped zinc oxide (AZO) thin films

    NASA Astrophysics Data System (ADS)

    Htwe, Zin Maung; Zhang, Yun-Dong; Yao, Cheng-Bao; Li, Hui; Yuan, Ping

    2017-04-01

    Aluminum doped zinc oxide (AZO) thin films were fabricated by simultaneous RF/DC magnetron sputtering technique on sapphire (Al2O3) substrate with different DC sputtering power 2, 6, 8 and 10 W respectively. The sputtered thin films were annealed at 350 °C in order to improve the crystal quality. AZO thin films are systematically analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-VIS spectrometer for structural and optical properties. XRD patterns show that all sputtered thin films are well crystallized with hexagonal wurtzite structure. SEM images reveal the average crystallite sizes are increased after doping Al in ZnO which agreed with the calculated values from XRD. All thin films possess high optical transmittance in visible region and optical band gap values are relatively increased with Al concentration. The ultrafast transient absorption (TA) of AZO was analyzed by femtosecond pump-probe spectroscopy. The kinetic TA curves were fitted by tri-exponential decay function and obtained decay time constants are found to be in few picosecond and nanosecond range for ultrafast and slow processes respectively. Third order nonlinear optical absorption and refraction coefficients were investigated by using Z-scan technique. The observed nonlinear coefficients are enhanced with Al concentration in ZnO.

  12. Effects of target angle on the properties of aluminum doped zinc oxide films prepared by DC magnetron sputtering for thin film solar cell applications.

    PubMed

    Park, Hyeongsik; Iftiquar, S M; Thuy, Trinh Than; Jang, Juyeon; Ahn, Shihyun; Kim, Sunbo; Lee, Jaehyeong; Jung, Junhee; Shin, Chonghoon; Kim, Minbum; Yi, Junsin

    2014-10-01

    An aluminum doped zinc oxide (AZO) films for front contacts of thin film solar cells, in this work, were prepared by DC magnetron sputtering with different target angles. Effects of target angles on the structural and electro-optical properties of AZO films were investigated. Also, to clarify the light trapping of textured AZO film, amorphous silicon thin film solar cells were fabricated on the textured AZO/glass substrate and the performance of solar cells were studied. The surface became more irregular with increasing the target angle due to larger grains. The self-surface textured morphology, which is a favorable property as front layer of solar cell, exhibited at target angle of 72.5 degrees. We obtained the films with various opto-electronic properties by controlling target angle from 32.5 degrees to 72.5 degrees. The spectral haze increased substantially with the target angle, whereas the electrical resistivity was increased. The conversion efficiency of amorphous silicon solar cells with textured AZO film as a front electrode was improved by the increase of short-circuit current density and fill factor, compared to cell with relatively flat AZO films.

  13. Atomic layer deposition of aluminum oxide films for carbon nanotube network transistor passivation.

    PubMed

    Grigoras, Kestutis; Zavodchikova, Marina Y; Nasibulin, Albert G; Kauppinen, Esko I; Ermolov, Vladimir; Franssila, Sami

    2011-10-01

    Ultra-thin (2-5 nm thick) aluminum oxide layers were grown on non-functionalized individual single walled carbon nanotubes (SWCNT) and their bundles by atomic layer deposition (ALD) technique in order to investigate the mechanism of the coating process. Transmission electron microscopy (TEM) was used to examine the uniformity and conformality of the coatings grown at different temperatures (80 degrees C or 220 degrees C) and with different precursors for oxidation (water and ozone). We found that bundles of SWCNTs were coated continuously, but at the same time, bare individual nanotubes remained uncoated. The successful coating of bundles was explained by the formation of interstitial pores between the individual SWCNTs constituting the bundle, where the precursor molecules can adhere, initiating the layer growth. Thicker alumina layers (20-35 nm thick) were used for the coating of bottom-gated SWCNT-network based field effect transistors (FETs). ALD layers, grown at different conditions, were found to influence the performance of the SWCNT-network FETs: low temperature ALD layers caused the ambipolarity of the channel and pronounced n-type conduction, whereas high temperature ALD processes resulted in hysteresis suppression in the transfer characteristics of the SWCNT transistors and preserved p-type conduction. Fixed charges in the ALD layer have been considered as the main factor influencing the conduction change of the SWCNT network based transistors.

  14. Effect of the polymer concentration on the Rayleigh-instability-type transformation in polymer thin films coated in the nanopores of anodic aluminum oxide templates.

    PubMed

    Tsai, Chia-Chan; Chen, Jiun-Tai

    2015-03-03

    We study the Rayleigh-instability-type transformation of polystyrene (PS) thin films coated in the nanopores of anodic aluminum oxide (AAO) templates. The PS thin films are fabricated using a solution-wetting method, in which the wall thicknesses are controlled by the concentrations of the polymer solutions and the diameters of the nanopores. By thermal annealing, the surfaces of the thin films undulate and the morphologies transform from nanotubes to Rayleigh-instability-induced nanostructures (short nanorods) and long nanorods. To understand the mechanism of the morphology transformation further, we construct the morphology diagrams by annealing the PS thin films at different temperatures and times. We observe that the morphology diagrams of the PS thin films prepared by different concentrations are similar, indicating that the transformation kinetics are not affected by the film thicknesses. The values of the undulation wavelengths, however, are controlled by the film thicknesses and the diameters of the nanopores.

  15. Evolution of insoluble eutectic Si particles in anodic oxidation films during adipic-sulfuric acid anodizing processes of ZL114A aluminum alloys

    NASA Astrophysics Data System (ADS)

    Hua, Lei; Liu, Jian-hua; Li, Song-mei; Yu, Mei; Wang, Lei; Cui, Yong-xin

    2015-03-01

    The effects of insoluble eutectic Si particles on the growth of anodic oxide films on ZL114A aluminum alloy substrates were investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The anodic oxidation was performed at 25°C and a constant voltage of 15 V in a solution containing 50 g/L sulfuric acid and 10 g/L adipic acid. The thickness of the formed anodic oxidation film was approximately 7.13 μm. The interpore distance and the diameters of the major pores in the porous layer of the film were within the approximate ranges of 10-20 nm and 5-10 nm, respectively. Insoluble eutectic Si particles strongly influenced the morphology of the anodic oxidation films. The anodic oxidation films exhibited minimal defects and a uniform thickness on the ZL114A substrates; in contrast, when the front of the oxide oxidation films encountered eutectic Si particles, defects such as pits and non-uniform thickness were observed, and pits were observed in the films.

  16. Influence of source and drain contacts on the properties of the indium-zinc oxide thin-film transistors based on anodic aluminum oxide gate dielectrics

    NASA Astrophysics Data System (ADS)

    Lan, Linfeng; Xu, Miao; Peng, Junbiao; Xu, Hua; Li, Min; Luo, Dongxiang; Zou, Jianhua; Tao, Hong; Wang, Lei; Yao, Rihui

    2011-11-01

    Thin-film transistors (TFTs) based on indium-zinc oxide (IZO) active layer and anodic aluminum oxide (Al2O3) gate dielectric layer were fabricated. The influence of source and drain (S/D) contacts on TFT performance was investigated by comparing IZO-TFTs with different S/D electrodes. The TFT with Mo S/D electrodes had higher output current and lower threshold voltage, but had poorer subthreshold swing and lower effective electron mobility compared to that with ITO S/D electrodes. By using x-ray photoelectron spectroscopy (XPS) depth profile analyzing method, it was observed that Mo was diffusing seriously into IZO, resulting in the variation of the effective channel length, thereby causing serious short-channel effect, poor subshreshold swing, and bad uniformity of the TFTs with Mo S/D electrodes.

  17. Chemical vapor deposition of aluminum oxide

    DOEpatents

    Gordon, Roy; Kramer, Keith; Liu, Xinye

    2000-01-01

    An aluminum oxide film is deposited on a heated substrate by CVD from one or more alkylaluminum alkoxide compounds having composition R.sub.n Al.sub.2 (OR').sub.6-n, wherein R and R' are alkyl groups and n is in the range of 1 to 5.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

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

    PubMed

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

    2016-02-17

    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.

  20. 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

  1. Ultrafine nanoporous palladium-aluminum film fabricated by citric acid-assisted hot-water-treatment of aluminum-palladium alloy film

    SciTech Connect

    Harumoto, Takashi; Tamura, Yohei; Ishiguro, Takashi

    2015-01-15

    Hot-water-treatment has been adapted to fabricate ultrafine nanoporous palladium-aluminum film from aluminum-palladium alloy film. Using citric acid as a chelating agent, a precipitation of boehmite (aluminum oxide hydroxide, AlOOH) on the nanoporous palladium-aluminum film was suppressed. According to cross-sectional scanning transmission electron microscopy observations, the ligament/pore sizes of the prepared nanoporous film were considerably small (on the order of 10 nm). Since this fabrication method only requires aluminum alloy film and hot-water with chelating agent, the ultrafine nanoporous film can be prepared simply and environmentally friendly.

  2. Atomic force microscopy identification of Al-sites on ultrathin aluminum oxide film on NiAl(110).

    PubMed

    Li, Yan Jun; Brndiar, J; Naitoh, Y; Sugawara, Y; Štich, I

    2015-12-18

    Ultrathin alumina film formed by oxidation of NiAl(110) was studied by non-contact atomic force microscopy in an ultra high vacuum at room temperature with the quest to provide the ultimate understanding of structure and bonding of this complicated interface. Using a very stiff Si cantilever with significantly improved resolution, we have obtained images of this system with unprecedented resolution, surpassing all the previous results. In particular, we were able to unambiguously resolve all the differently coordinated aluminum atoms. This is of importance as the previous images provide very different image patterns, which cannot easily be reconciled with the existing structural models. Experiments are supported by extensive density functional theory modeling. We find that the system is strongly ionic and the atomic force microscopy images can reliably be understood from the electrostatic potential which provides an image model in excellent agreement with the experiments. However, in order to resolve the finer contrast features we have proposed a more sophisticated model based on more realistic approximants to the incommensurable alumina interface.

  3. Embedded argon as a tool for sampling local structure in thin plasma deposited aluminum oxide films

    SciTech Connect

    Prenzel, Marina; Kortmann, Annika; Keudell, Achim von; Arcos, Teresa de los; Winter, Joerg

    2012-11-15

    Al{sub 2}O{sub 3} thin films, either amorphous or of varying degrees of crystallinity, were deposited by two-frequency radio-frequency magnetron sputtering. Film crystallinity was investigated by Fourier transform infrared spectroscopy and X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) was employed to determine the amount of Ar naturally trapped within the films during the deposition process. A clear correlation was found between the existence of crystalline phases, as determined by XRD, and a shift towards lower binding energy positions of the Ar2p core levels of embedded gas. The shift is due to differences in the local Al{sub 2}O{sub 3} matrix (amorphous or crystalline) of the embedded gas, thus, providing an XPS fingerprint that can be used to qualitatively determine the presence or absence of crystalline phases in very thin films.

  4. Thin Anodic Oxide Films on Aluminum Alloys and Their Role in the Durability of Adhesive Bonds.

    DTIC Science & Technology

    1980-02-01

    of each created interface B. Dynamic environment 1) stress 2) humidity and other atmospheric gases 3) temperature C. Failure analysis 1) fracture 2...fatigue 3) corrosion Studies involving the appropriate permutations and combina- tions of A, B, and C are needed to generate a data base for ad...is prominent ! -1 TABLE I NOMINAL CHEMICAL COMPOSITION OF ALUMINUM ALLOYS Alloy Si Cu Mn Mg Cr Zn Zr 2024 -- 4.5 0.6 1.5 ---- -- 7050 -- 2.3 -- 2.25

  5. Pull-test adhesion measurements of diamondlike carbon films on silicon carbide, silicon nitride, aluminum oxide, and zirconium oxide

    SciTech Connect

    Erck, R.A.; Nichols, F.A.; Dierks, J.F.

    1993-10-01

    Hydrogenated amorphous carbon films or diamondlike carbon (DLC) films were formed by ion-beam deposition of 400 eV methane (CH{sub 4}) ions on several smooth and rough ceramics, as well as on ceramics coated with a layer of Si and Ti. Adhesion was measured by the pin-pull method. Excellent adhesion was measured for smooth SiC and Si{sub 3}N{sub 4}, but adhesion of DLC to Al{sub 2}O{sub 3} and ZrO{sub 2} was negligible. The use of a Si bonding interlayer produced good adhesion to all the substrates, but a Ti layer was ineffective because bonding between the DLC film and Ti was poor. The presence of surface roughness appeared to greatly increase the measured adhesion in all cases. Bulk thermodynamic calculations are not directly applicable to bonding at the interface. If the standard enthalpy of formation for reaction between CH{sub 4} and substrate is calculated assumpting a carbide or carbon phase is produced, a relation is seen between reaction enthalpy and relative adhesion. Large positive enthalpies are associated with poor adhesion; negative or small positive enthalpies are associated with good adhesion. This relation between enthalpy and adhesion was also observed for DLC deposited on Si. Lack of adhesion to Ti was attributed to inadvertent formation of a surface oxide layer that rendered the enthalpy for reaction with CH{sub 4} strongly positive and similar in magnitude to that for Al{sub 2}O{sub 3} and ZrO{sub 2}.

  6. Optical constants of off-stoichiometric aluminum oxide thin film in 6-20 nm soft-X-ray/extreme ultraviolet region

    NASA Astrophysics Data System (ADS)

    Sinha, Mangalika; Sharma, Saurabh; Singh, Amol; Modi, Mohammed H.

    2016-10-01

    In this study, the optical constants of a sputter-deposited aluminum oxide thin film are measured in the soft-X-ray wavelength region of 6-20 nm using an angle-dependent X-ray reflectivity technique at the Indus-1 synchrotron radiation source. The chemical composition of the aluminum oxide thin film is analyzed by an X-ray photoelectron spectroscopy technique. Grazing incidence X-ray reflectivity results indicate that the density of the film is lower (2.93 g·cm-3) than that of bulk alumina (3.97 g·cm-3). The experimentally obtained optical constants correlate with the film composition and density. It is found that the experimentally measured delta and beta values are 5-33% higher than the tabulated values except those near the Al L edge (17 nm) region, where the experimentally obtained beta values are 7-20% lower and the delta values are 50-120% higher. This large mismatch observed between the experimental values and Henke et al. data is attributed to the reduced film density and the presence of a mixed phase of AlO x and Al2O3, as evidenced by X-ray photoelectron spectroscopy.

  7. Atomic scale structure of amorphous aluminum oxyhydroxide, oxide and oxycarbide films probed by very high field (27)Al nuclear magnetic resonance.

    PubMed

    Baggetto, L; Sarou-Kanian, V; Florian, P; Gleizes, A N; Massiot, D; Vahlas, C

    2017-03-15

    The atomic scale structure of aluminum in amorphous alumina films processed by direct liquid injection chemical vapor deposition from aluminum tri-isopropoxide (ATI) and dimethyl isopropoxide (DMAI) is investigated by solid-state (27)Al nuclear magnetic resonance (SSNMR) using a very high magnetic field of 20.0 T. This study is performed as a function of the deposition temperature in the range 300-560 °C, 150-450 °C, and 500-700 °C, for the films processed from ATI, DMAI (+H2O), and DMAI (+O2), respectively. While the majority of the films are composed of stoichiometric aluminum oxide, other samples are partially or fully hydroxylated at low temperature, or contain carbidic carbon when processed from DMAI above 500 °C. The quantitative analysis of the SSNMR experiments reveals that the local structure of these films is built from AlO4, AlO5, AlO6 and Al(O,C)4 units with minor proportions of the 6-fold aluminum coordination and significant amounts of oxycarbides in the films processed from DMAI (+O2). The aluminum coordination distribution as well as the chemical shift distribution indicate that the films processed from DMAI present a higher degree of structural disorder compared to the films processed from ATI. Hydroxylation leads to an increase of the 6-fold coordination resulting from the trend of OH groups to integrate into AlO6 units. The evidence of an additional environment in films processed from DMAI (+O2) by (27)Al SSNMR and first-principle NMR calculations on Al4C3 and Al4O4C crystal structures supports that carbon is located in Al(O,C)4 units. The concentration of this coordination environment strongly increases with increasing process temperature from 600 to 700 °C favoring a highly disordered structure and preventing from crystallizing into γ-alumina. The obtained results are a valuable guide to the selection of process conditions for the CVD of amorphous alumina films with regard to targeted applications.

  8. Influence of growth temperature on electrical, optical, and plasmonic properties of aluminum:zinc oxide films grown by radio frequency magnetron sputtering

    SciTech Connect

    Dondapati, Hareesh; Santiago, Kevin; Pradhan, A. K.

    2013-10-14

    We have investigated the responsible mechanism for the observation of metallic conductivity at room temperature and metal-semiconductor transition (MST) at lower temperatures for aluminum-doped zinc oxide (AZO) films. AZO films were grown on glass substrates by radio-frequency magnetron sputtering with varying substrate temperatures (T{sub s}). The films were found to be crystalline with the electrical resistivity close to 1.1 × 10{sup −3} Ω cm and transmittance more than 85% in the visible region. The saturated optical band gap of 3.76 eV was observed for the sample grown at T{sub s} of 400 °C, however, a slight decrease in the bandgap was noticed above 400 °C, which can be explained by Burstein–Moss effect. Temperature dependent resistivity measurements of these highly conducting and transparent films showed a MST at ∼110 K. The observed metal-like and metal-semiconductor transitions are explained by taking into account the Mott phase transition and localization effects due to defects. All AZO films demonstrate crossover in permittivity from positive to negative and low loss in the near-infrared region, illustrating its applications for plasmonic metamaterials, including waveguides for near infrared telecommunication region. Based on the results presented in this study, the low electrical resistivity and high optical transmittance of AZO films suggested a possibility for the application in the flexible electronic devices, such as transparent conducting oxide film on LEDs, solar cells, and touch panels.

  9. Influence of growth temperature on electrical, optical, and plasmonic properties of aluminum:zinc oxide films grown by radio frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Dondapati, Hareesh; Santiago, Kevin; Pradhan, A. K.

    2013-10-01

    We have investigated the responsible mechanism for the observation of metallic conductivity at room temperature and metal-semiconductor transition (MST) at lower temperatures for aluminum-doped zinc oxide (AZO) films. AZO films were grown on glass substrates by radio-frequency magnetron sputtering with varying substrate temperatures (Ts). The films were found to be crystalline with the electrical resistivity close to 1.1 × 10-3 Ω cm and transmittance more than 85% in the visible region. The saturated optical band gap of 3.76 eV was observed for the sample grown at Ts of 400 °C, however, a slight decrease in the bandgap was noticed above 400 °C, which can be explained by Burstein-Moss effect. Temperature dependent resistivity measurements of these highly conducting and transparent films showed a MST at ˜110 K. The observed metal-like and metal-semiconductor transitions are explained by taking into account the Mott phase transition and localization effects due to defects. All AZO films demonstrate crossover in permittivity from positive to negative and low loss in the near-infrared region, illustrating its applications for plasmonic metamaterials, including waveguides for near infrared telecommunication region. Based on the results presented in this study, the low electrical resistivity and high optical transmittance of AZO films suggested a possibility for the application in the flexible electronic devices, such as transparent conducting oxide film on LEDs, solar cells, and touch panels.

  10. Influence of Oxygen Gas Ratio on the Properties of Aluminum-Doped Zinc Oxide Films Prepared by Radio Frequency Magnetron Sputtering.

    PubMed

    Kim, Minha; Jang, Yong-Jun; Jung, Ho-Sung; Song, Woochang; Kang, Hyunil; Kim, Eung Kwon; Kim, Donguk; Yi, Junsin; Lee, Jaehyeong

    2016-05-01

    Aluminum-doped zinc oxide (AZO) thin films were deposited on glass and polyimide substrates using radio frequency magnetron sputtering. We investigated the effects of the oxygen gas ratio on the properties of the AZO films for Cu(In,Ga)Se2 thin-film solar cell applications. The structural and optical properties of the AZO thin films were measured using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and UV-Visible-NIR spectrophotometry. The oxygen gas ratio played a crucial role in controlling the optical as well as electrical properties of the films. When oxygen gas was added into the film, the surface AZO thin films became smoother and the grains were enlarged while the preferred orientation changed from (0 0 2) to (1 0 0) plane direction of the hexagonal phase. An improvement in the transmittance of the AZO thin films was achieved with the addition of 2.5-% oxygen gas. The electrical resistivity was highly increased even for a small amount of the oxygen gas addition.

  11. Effect of the ion-beam bombardment and annealing temperature on sol-gel derived yttrium aluminum oxide film as liquid crystal alignment layer

    NASA Astrophysics Data System (ADS)

    Jeong, Hae-Chang; Heo, Gi-Seok; Kim, Eun-Mi; Lee, Ju Hwan; Han, Jeong-Min; Seo, Dae-Shik

    2017-02-01

    We demonstrated a homogeneous liquid-crystal (LC) alignment state on yttrium aluminum oxide (YAlO) films, where the alignment was induced by ion-beam (IB) irradiation. Topographical analysis was performed by atomic force microscopy as a function of annealing temperature. Higher annealing temperatures yielded a smoother surface, accompanied by reduced light scattering. Transparency in the visible region increased on the surface fabricated at higher annealing temperatures. LC alignment mechanism was determined by X-ray diffraction (XRD) analysis. Moreover, IB-irradiated YAlO films annealed at temperatures greater than 200 °C exhibited good thermal stability and low capacitance-voltage hysteresis. The IB-irradiated YAlO films are suitable as alternative alignment layers in advanced LC display applications.

  12. Improving the direct electron transfer in monolithic bioelectrodes prepared by immobilization of FDH enzyme on carbon-coated anodic aluminum oxide films

    NASA Astrophysics Data System (ADS)

    Castro-Muñiz, Alberto; Hoshikawa, Yasuto; Komiyama, Hiroshi; Nakayama, Wataru; Itoh, Tetsuji; Kyotani, Takashi

    2016-02-01

    The present work reports the preparation of binderless carbon-coated porous films and the study of their performance as monolithic bioanodes. The films were prepared by coating anodic aluminum oxide (AAO) films with a thin layer of nitrogen-doped carbon by chemical vapor deposition. The films have cylindrical straight pores with controllable diameter and length. These monolithic films were used directly as bioelectrodes by loading the films with D-fructose dehydrogenase (FDH), an oxidoreductase enzyme that catalyzes the oxidation of D-fructose to 5-keto-D-fructose. The immobilization of the enzymes was carried out by physical adsorption in liquid phase and with an electrostatic attraction method. The latter method takes advantage of the fact that FDH is negatively charged during the catalytic oxidation of fructose. Thus the immobilization was performed under the application of a positive voltage to the CAAO film in a FDH-fructose solution in McIlvaine buffer (pH 5) at 25 ºC. As a result, the FDH modified electrodes with the latter method show much better electrochemical response than that with the conventional physical adsorption method. Due to the singular porous structure of the monolithic films, which consists of an array of straight and parallel nanochannels, it is possible to rule out the effect of the diffusion of the D-fructose into the pores. Thus the improvement in the performance upon using the electrostatic attraction method can be ascribed not only to a higher uptake, but also to a more appropriate molecule orientation of the enzyme units on the surface of the electrodes.

  13. Characteristics of low-resistivity aluminum-doped zinc oxide films deposited at room temperature by off-axis radio-frequency sputtering on flexible plastic substrates

    NASA Astrophysics Data System (ADS)

    Wang, Li-Min; Wang, Chih-Yi; Jheng, Ciao-Ren; Wu, Syu-Jhan; Sai, Chen-Kai; Lee, Ya-Ju; Chiang, Ching-Yu; Shew, Bor-Yuan

    2016-08-01

    The crystalline structure, morphology, composition, electrical transport, and optical properties of aluminum-doped zinc oxide (AZO) films are studied for applications in transparent electronics and optoelectronic devices. AZO thin films of c-axis-oriented growth and with different thickness were deposited on PET flexible plastic substrates at room temperature by rf magnetron sputtering. A larger grain size with a decreased strain ɛ value is observed in a thicker film, while changes in composition for films with different thicknesses are insignificant. Moreover, the resistivity of film decreases with increasing thickness, and the low-temperature electrical transport properties can be described by the scenario of quantum corrections to conductivity. With the room-temperature growth conditions, the resistivity of 4.5 × 10-4 Ω cm, carrier concentration of 6.4 × 1020 cm-3, and transmittance of 80 % for the 1100-nm-thick film are obtained. In addition, the optical bandgap energy decreases with increasing film thickness, which can be attributed to the bandgap renormalization and crystallite size effects.

  14. Controlled aluminum-induced crystallization of an amorphous silicon thin film by using an oxide-layer diffusion barrier

    NASA Astrophysics Data System (ADS)

    Hwang, Ji-Hyun; Kwak, Hyunmin; Kwon, Myeung Hoi

    2014-03-01

    Aluminum-induced crystallization (AIC) of amorphous silicon with an Al2O3 diffusion barrier was investigated for controlling Si crystallization and preventing layer exchange during the annealing process. An Al2O3 layer was deposited between the a-Si and the Al films (a-Si/Al2O3/Al/Glass) and was blasted with an air spray gun with alumina beads to form diffusion channels between the Si and the Al layers. During the annealing process, small grain Si x Al seeds were formed at the channels. Then, the Al2O3 diffusion barrier was restructured to close the channels and prevent further diffusion of Al atoms into the a-Si layer. A polycrystalline Si film with (111), (220) and (311) crystallization peaks in the X-ray diffraction pattern was formed by annealing at 560 °C in a conventional furnace. That film showed a p-type semiconducting behavior with good crystallinity and a large grain size of up to 14.8 µm. No layer conversion occurred between the Si and the Al layers, which had been the fundamental obstacle to the applications in the crystallization of a-Si films by using the AIC method.

  15. Air-Impregnated Nanoporous Anodic Aluminum Oxide Layers for Enhancing the Corrosion Resistance of Aluminum.

    PubMed

    Jeong, Chanyoung; Lee, Junghoon; Sheppard, Keith; Choi, Chang-Hwan

    2015-10-13

    Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance.

  16. Frictional behavior and adhesion of Ag and Au films applied to aluminum oxide by oxygen-ion assisted Screen Cage Ion Plating (SCIP)

    NASA Technical Reports Server (NTRS)

    Spalvins, Talivaldis; Sliney, Harold E.

    1994-01-01

    A modified dc-diode ion plating system, by utilizing a metallic screen cage as a cathode, is introduced for coating nonconductors such as ceramics. Screen cage ion plating (SCIP) is used to apply Ag and Au lubricating films on aluminum oxide surfaces. This process has excellent ability to coat around corners to produce three-dimensional coverage of the substrate. A dramatic increase in adhesion is achieved when plating is performed in a reactive 50 percent O2 - 50 percent Ar glow discharge compared to the adhesion when plating is performed in 100 percent Ar. The presence of oxygen ion assistance contributes to the excellent adhesion as measured in a pull-type adhesion tester. The Ag and Au film adhesion is significantly increased (less than 70MPa) and generally exceeds the cohesion of the substrate such that portions of the alumina are pulled out.

  17. Dry lubricant films for aluminum forming.

    SciTech Connect

    Wei, J.; Erdemir, A.; Fenske, G. R.

    1999-03-30

    During metal forming process, lubricants are crucial to prevent direct contact, adhesion, transfer and scuffing of workpiece materials and tools. Boric acid films can be firmly adhered to the clean aluminum surfaces by spraying their methanol solutions and provide extremely low friction coefficient (about 0.04). The cohesion strengths of the bonded films vary with the types of aluminum alloys (6061, 6111 and 5754). The sheet metal forming tests indicate that boric acid films and the combined films of boric acid and mineral oil can create larger strains than the commercial liquid and solid lubricants, showing that they possess excellent lubricities for aluminum forming. SEM analyses indicate that boric acid dry films separate the workpiece and die materials, and prevent their direct contact and preserve their surface qualities. Since boric acid is non-toxic and easily removed by water, it can be expected that boric acid films are environmentally friendly, cost effective and very efficient lubricants for sheet aluminum cold forming.

  18. Aluminum doped nickel oxide thin film with improved electrochromic performance from layered double hydroxides precursor in situ pyrolytic route

    NASA Astrophysics Data System (ADS)

    Shi, Jingjing; Lai, Lincong; Zhang, Ping; Li, Hailong; Qin, Yumei; Gao, Yuanchunxue; Luo, Lei; Lu, Jun

    2016-09-01

    Electrochromic materials with unique performance arouse great interest on account of potential application values in smart window, low-power display, automobile anti-glare rearview mirror, and e-papers. In this paper, high-performing Al-doped NiO porous electrochromic film grown on ITO substrate has been prepared via a layered double hydroxides(LDHs) precursor in situ pyrolytic route. The Al3+ ions distributed homogenously within the NiO matrix can significantly influence the crystallinity of Ni-Al LDH and NiO:Al3+ films. The electrochromic performance of the films were evaluated by means of UV-vis absorption spectroscopy, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry(CA) measurements. In addition, the ratio of Ni3+/Ni2+ also varies with Al content which can lead to different electrochemical performances. Among the as-prepared films, NiO film prepared from Ni-Al (19:1) LDH show the best electrochromic performance with a high transparency of 96%, large optical modulation range (58.4%), fast switching speed (bleaching/coloration times are 1.8/4.2 s, respectively) and excellent durability (30% decrease after 2000 cycles). The improved performance was owed to the synergy of large NiO film specific surface area and porous morphology, as well as Al doping stifled the formation of Ni3+ making bleached state more pure. This LDHs precursor pyrolytic method is simple, low-cost and environmental benign and is feasible for the preparation of NiO:Al and other Al-doped oxide thin film.

  19. H₂O Dissociation-Induced Aluminum Oxide Growth on Oxidized Al(111) Surfaces.

    PubMed

    Liu, Qianqian; Tong, Xiao; Zhou, Guangwen

    2015-12-08

    The interaction of water vapor with amorphous aluminum oxide films on Al(111) is studied using X-ray photoelectron spectroscopy to elucidate the passivation mechanism of the oxidized Al(111) surfaces. Exposure of the aluminum oxide film to water vapor results in self-limiting Al2O3/Al(OH)3 bilayer film growth via counter-diffusion of both ions, Al outward and OH inward, where a thinner starting aluminum oxide film is more reactive toward H2O dissociation-induced oxide growth because of the thickness-dependent ionic transport in the aluminum oxide film. The aluminum oxide film exhibits reactivity toward H2O dissociation in both low-vapor pressure [p(H2O) = 1 × 10(-6) Torr] and intermediate-vapor pressure [p(H2O) = 5 Torr] regimes. Compared to the oxide film growth by exposure to a p(H2O) of 1 × 10(-6) Torr, the exposure to a p(H2O) of 5 Torr results in the formation of a more open structure of the inner Al(OH)3 layer and a more compact outer Al2O3 layer, demonstrating the vapor-pressure-dependent atomic structure in the passivating layer.

  20. Fabrication of electrodes on the aluminum doped zinc oxide thin films using an ultraviolet laser direct-patterning technology

    NASA Astrophysics Data System (ADS)

    Hsiao, Wen-Tse; Tseng, Shih-Feng; Kuo, Chao-Hui; Huang, Kuo-Cheng; Chiang, Donyau; Yao, Pin-Chiun; Chen, Ming-Fei

    Because transparent conductive oxide (TCO) thin films have more than 80% transmittance in visible spectrum, and high electrical conductivity, the TCO films are widely applied to flat panel displays and solar cells as transparent electrode materials. This study aims to develop a direct patterning technology on ZnO:Al (AZO) thin films by a diode-pumped solid state ultraviolet laser. The electrode patterns with array structures on AZO thin films were generated by a high-speed galvanometric scanning system. The optoelectronic properties of a patterned electrode have strong relation with the laser pulse frequency, the scan speed, and the patterning time. The surface morphology and roughness of patterned electrode were measured by three dimension confocal microscope and field emission scanning electron microscope, respectively. The resistivity of AZO thin films before and after laser patterning was measured by a four point probe instrument. The optical transmittance was recorded by a UV/VIS/NIR spectrophotometer. The experimental results indicated that the edge line width and depth decreased with increasing the scan speed. After the array patterns structure were formed by laser dry etching, the roughness Ra values of patterned area increased from 0.06 μm to 0.16 μm. These transmittances of patterned structure from 400 nm to 800 nm wavelengths averagely reached to 82%. The measured results of electrical conductively revealed that the resistivity gradually increased with increasing the pulse repetition frequency. In addition, surface morphologic examination on the straight lines, corners, and etched regions of patterned films revealed no micro-cracks observed which meant the patterned surface had a better surface quality.

  1. Fabrication of silver decorated anodic aluminum oxide substrate and its optical properties on surface-enhanced Raman scattering and thin film interference.

    PubMed

    Ji, Nan; Ruan, Weidong; Wang, Chunxu; Lu, Zhicheng; Zhao, Bing

    2009-10-06

    In this paper, a simple method to fabricate a three-dimensional (3D) nanostructure decorated with Ag nanoparticles for surface-enhanced Raman scattering (SERS) is demonstrated. Highly ordered porous anodic aluminum oxide (AAO) templates were employed to construct these compound nanostructures. First, the AAO templates were fabricated using a two-step anodization approach. Second, an alternating current (AC) electrochemical deposition was used to fill AAO templates with Ag nanoparticles. Taking 4-mercaptopyridine (4-MPy) as the probing molecule, high-quality SERS spectra were observed. The UV-vis mirror reflection spectra were measured to investigate the surface plasma resonance (SPR) absorbance. An interesting phenomenon of SPR-affected thin film interference was observed. SERS mapping was performed to characterize the homogeneity of as-prepared substrates. Good homogeneity and stability make these substrates good candidates for SERS spectroscopy.

  2. Effect of Pore Size and Film Thickness on Gold-Coated Nanoporous Anodic Aluminum Oxide Substrates for Surface-Enhanced Raman Scattering Sensor

    PubMed Central

    Kassu, Aschalew; Farley, Carlton; Sharma, Anup; Kim, Wonkyu; Guo, Junpeng

    2015-01-01

    A sensitive surface enhanced Raman scattering chemical sensor is demonstrated by using inexpensive gold-coated nanoporous anodic aluminum oxide substrates. To optimize the performance of the substrates for sensing by the Surface-enhanced Raman scattering (SERS) technique, the size of the nanopores is varied from 18 nm to 150 nm and the gold film thickness is varied from 30 nm to 120 nm. The sensitivity of gold-coated nanoporous surface enhanced Raman scattering sensor is characterized by detecting low concentrations of Rhodamine 6G laser dye molecules. The morphology of the SERS substrates is characterized by atomic force microscopy. Optical properties of the nanoporous SERS substrates including transmittance, reflectance, and absorbance are also investigated. Relative signal enhancement is plotted for a range of substrate parameters and a detection limit of 10−6 M is established. PMID:26633402

  3. Low temperature near infrared plasmonic gas sensing of gallium and aluminum doped zinc oxide thin films from colloidal inks (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Sturaro, Marco; Della Gaspera, Enrico; Martucci, Alessandro; Guglielmi, Massimo

    2015-08-01

    We obtained Gallium-doped and Aluminum-doped Zinc Oxide nanocrystals by non aqueous colloidal heat-up synthesis. These nanocrystals are transparent in the visible range but exhibit localized surface plasmon resonances (LSPRs) in the near IR range, tunable and shiftable with dopant concentration (up to 20% mol nominal). GZO and AZO inks can be deposited by spin coating, dip coating or spray coating on glass or silicon, leading to uniform and high optical quality thin films. To enhance absorbtion in the infrared region, samples can be annealed in inert or reductant atmosphere (N2/Argon or H2 in Argon) resulting in plasmon intensity enhancement due to oxygen vacancies and conduction band electrons density increment. Then IR plasmon has been exploited for gas sensing application, according to the plasmon shifting for carrier density variations, due to electrons injection or removal by the target gas/sample chemical interactions. To obtain a functional sensor at low temperature, another treatment was investigated, involving surfanctant removal by dipping deposited films in a solution of organic acid, tipically oxalic acid in acetonitrile; such process could pave the way to obtain similar sensors deposited on plastics. Finally, GZO and AZO thin films proved sensibility to H2 and NOx, and in particular circumstances also to CO, from room temperature to 200°C. Sensibility behavior for different dopant concentration and temperture was investigated both in IR plasmon wavelengths (~2400 nm) and zinc oxide band gap (~370 nm). An enhancement in sensitivity to H2 is obtained by adding Pt nanoparticles, exploiting catalytic properties of Platinum for hydrogen splitting.

  4. Oxide film microstructure: the link between surface preparation processes and strength/durability of adhesively bonded aluminum. Final report

    SciTech Connect

    Hsia, K. Jimmy; Pearlstein, Arne J.; Scheeline, Alexander; Shang, Jian Ku

    2000-11-30

    Strength and durability of adhesive bonding of aluminum alloys structures are intrinsically determined by the surface microstructures and interfacial failure micromechanisms. The current project presents a multidisciplinary approach to addressing critical issues controlling the strength and durability of adhesive bonds of aluminum alloys. Three main thrust areas have been pursued: surface treatment technology development to achieve desirable surface microstructures; relationship between surface structure and properties of adhesive bonds; and failure mechanisms of adhesively bonded components.

  5. Surface wettability of macroporous anodized aluminum oxide.

    PubMed

    Buijnsters, Josephus G; Zhong, Rui; Tsyntsaru, Natalia; Celis, Jean-Pierre

    2013-04-24

    The correlation between the structural characteristics and the wetting of anodized aluminum oxide (AAO) surfaces with large pore sizes (>100 nm) is discussed. The roughness-induced wettability is systematically examined for oxide films grown by a two-step, high-field anodization in phosphoric acid of three different concentrations using a commercial aluminum alloy. This is done for the as-synthesized AAO layers, after various degrees of pore widening by a wet chemical etching in phosphoric acid solution, and upon surface modification by either Lauric acid or a silane. The as-grown AAO films feature structurally disordered pore architectures with average pore openings in the range 140-190 nm but with similar interpore distances of about 405 nm. The formation of such AAO structures induces a transition from slightly hydrophilic to moderately hydrophobic surfaces up to film thicknesses of about 6 μm. Increased hydrophobicity is obtained by pore opening and a maximum value of the water contact angle (WCA) of about 128° is measured for AAO arrays with a surface porosity close to 60%. Higher surface porosity by prolonged wet chemical etching leads to a rapid decrease in the WCA as a result of the limited pore wall thickness and partial collapse of the dead-end pore structures. Modification of the AAO surfaces by Lauric acid results in 5-30° higher WCA's, whereas near-superhydrophobicity (WCA ~146°) is realized through silane coating. The "rose petal effect" of strongly hydrophobic wetting with high adhesive force on the produced AAO surfaces is explained by a partial penetration of water through capillary action into the dead-end pore cavities which leads to a wetting state in-between the Wenzel and Cassie states. Moreover, practical guidelines for the synthesis of rough, highly porous AAO structures with controlled wettability are provided and the possibility of forming superhydrophobic surfaces is evaluated.

  6. Corrosion protection of silver-based telescope mirrors using evaporated anti-oxidation overlayers and aluminum oxide films by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Fryauf, David M.; Phillips, Andrew C.; Kobayashi, Nobuhiko P.

    2016-09-01

    An urgent demand remains in astronomy for high-reflectivity silver mirrors that can withstand years of exposure in observatory environments. The University of California Observatories Astronomical Coatings Lab has undertaken development of protected silver coatings suitable for telescope mirrors that maintain high reflectivity at wavelengths from 340 nm through the mid-infrared spectrum. We present results on superior protective layers of transparent dielectrics produced by evaporation and atomic layer deposition. Several novel coating recipes have been developed with ion-assisted electron beam deposition (IAEBD) of various fluorides, oxides, and nitrides in combination with conformal layers of aluminum oxide (AlOx) deposited by ALD using trimethylaluminum as a metal precursor and water vapor as a reactant. Extending on our previous results demonstrating the superior durability of ALD-based AlOx top barrier layers over conventionally-deposited AlOx, this work investigates the effects on mirror barrier durability comparing different anti-oxidation materials on Ag with an identical AlOx top barrier layer deposited by ALD. Samples of coating recipes with different anti-oxidation layers undergo aggressive environmental testing, including high temperature/high humidity (HTHH), in which samples are exposed to an environment of 80% humidity at 80°C for ten days in a simple test set-up. While most samples show fairly successful endurance after HTHH testing, visible results suggest that MgAl2O4, Al2O3, and AlN anti-oxidation layers offer enhanced robust protection against chemical corrosion and moisture in an accelerated aging environment, which is attributed to superior adhesion and intermolecular bonding between the Al-based anti-oxidation layers and the AlOx top barrier layer. Mirror samples are further characterized by reflectivity/absorption before and after deposition of oxide coatings. We also show that the performance of the ALD-AlOx barrier layer depends in part

  7. Vanadium oxides on aluminum oxide supports. 1. Surface termination and reducibility of vanadia films on alpha-Al2O3(0001).

    PubMed

    Todorova, Tanya K; Ganduglia-Pirovano, M Veronica; Sauer, Joachim

    2005-12-15

    Using density functional theory and statistical thermodynamics, we obtained the phase diagram of thin VnOm films of varying thickness (approximately 2-6 A, 1-6 vanadium layers) supported on alpha-Al2O3(0001). Depending on the temperature, oxygen pressure, and vanadium concentration, films with different thickness and termination may form. In ultrahigh vacuum (UHV), at room temperature and for low vanadium concentrations, an ultrathin (1 x 1) O=V-terminated film is most stable. As more vanadium is supplied, the thickest possible films form. Their structures and terminations correspond to previous findings for the (0001) surface of bulk V2O3 [Kresse et al., Surf. Sci. 2004, 555, 118]. The presence of surface vanadyl (O=V) groups is a prevalent feature. They are stable up to at least 800 K in UHV. Vanadyl oxygen atoms induce a V(2p) core-level shift of about 2 eV on the surface V atoms. The reducibility of the supported films is characterized by the energy of oxygen defect formation. For the stable structures, the results vary between 4.11 and 3.59 eV per 1/2O2. In contrast, oxygen removal from the V2O5(001) surface is much easier (1.93 eV). This provides a possible explanation for the lower catalytic activity of vanadium oxides supported on alumina compared to that of crystalline vanadia particles.

  8. THE BEHAVIOR OF SUPERALLOY OXIDE FILMS IN MOLTEN SALTS.

    DTIC Science & Technology

    NICKEL ALLOYS , CORROSION), (*FILMS, OXIDES), CORROSION RESISTANT ALLOYS , SALTS, CORROSIVE LIQUIDS, HIGH TEMPERATURE, NICKEL COMPOUNDS, SODIUM...COMPOUNDS, SULFATES, CHLORIDES, CHROMIUM COMPOUNDS, CHROMIUM ALLOYS , MOLYBDENUM ALLOYS , COBALT ALLOYS , ALUMINUM ALLOYS , TITANIUM ALLOYS , IRON ALLOYS , NICKEL, OXIDATION

  9. Aluminum-Oxide Temperatures on the Mark VB, VE, VR, 15, and Mark 25 Assemblies

    SciTech Connect

    Aleman, S.E.

    2001-07-17

    The task was to compute the maximum aluminum-oxide and oxide-coolant temperatures of assemblies cladded in 99 plus percent aluminum. The assemblies considered were the Mark VB, VE, V5, 15 and 25. These assemblies consist of nested slug columns with individual uranium slugs cladded in aluminum cans. The CREDIT code was modified to calculate the oxide film thickness and the aluminum-oxide temperature at each axial increment. The information in this report will be used to evaluate the potential for cladding corrosion of the Mark 25 assembly.

  10. Aluminum-Oxide Temperatures on the Mark VB, VE, VR, 15, and Mark 25 Assemblies

    SciTech Connect

    Aleman, S.E.

    2001-07-17

    The task was to compute the maximum aluminum-oxide and oxide-coolant temperatures of assemblies cladded in 99+ percent aluminum. The assemblies considered were the Mark VB, VE, V5, 15 and 25. These assemblies consist of nested slug columns with individual uranium slugs cladded in aluminum cans. The CREDIT code was modified to calculate the oxide film thickness and the aluminum-oxide temperature at each axial increment. This information in this report will be used to evaluate the potential for cladding corrosion of the Mark 25 assembly.

  11. The pro-oxidant activity of aluminum.

    PubMed

    Exley, Christopher

    2004-02-01

    Aluminum, a non-redox-active metal is, nevertheless, a pro-oxidant both in in vitro preparations and in vivo. It facilitates both superoxide- and iron-driven biological oxidation by mechanisms that remain to be resolved. More than 10 years ago Fridovich and colleagues suggested that the facilitation of superoxide-driven biological oxidation by aluminum was due to an interaction between the metal and the superoxide radical anion (Free Radic. Biol. Med. 13: 79-81; 1992). This thesis has been examined herein and it is concluded that much, if not all, of the pro-oxidant activity of aluminum might be explained by the formation of an aluminum superoxide semireduced radical ion.

  12. Nanostructures Using Anodic Aluminum Oxide

    NASA Astrophysics Data System (ADS)

    Valmianski, Ilya; Monton, Carlos M.; Pereiro, Juan; Basaran, Ali C.; Schuller, Ivan K.

    2013-03-01

    We present two fabrication methods for asymmetric mesoscopic dot arrays over macroscopic areas using anodic aluminum oxide templates. In the first approach, metal is deposited at 45o to the template axis to partially close the pores and produce an elliptical shadow-mask. In the second approach, now underway, nanoimprint lithography on a polymer intermediary layer is followed by reactive ion etching to generate asymmetric pore seeds. Both these techniques are quantified by an analysis of the lateral morphology and lattice of the pores or dots using scanning electron microscopy and a newly developed MATLAB based code (available for free download at http://ischuller.ucsd.edu). The code automatically provides a segmentation of the measured area and the statistics of morphological properties such as area, diameter, and eccentricity, as well as the lattice properties such as number of nearest neighbors, and unbiased angular and radial two point correlation functions. Furthermore, novel user defined statistics can be easily obtained. We will additionally present several applications of these methods to superconducting, ferromagnetic, and organic nanostructures. This work is supported by AFOSR FA9550-10-1-0409

  13. Graphene tunnel junctions with aluminum oxide barrier

    NASA Astrophysics Data System (ADS)

    Feng, Ying; Trainer, Daniel J.; Chen, Ke

    2016-10-01

    We report a development of graphene tunnel junctions made by chemical vapor deposition grown graphene and sputtered aluminum insulating by an in-situ grown aluminum oxide. The thin oxide layer formed in between the metal layer and the two-dimensional material is a crucial part of a tunnel junction. We characterized surface morphology of oxide layers and studied tunneling spectra of lead and silver tunnel junctions to estimate the quality of the aluminum oxide. The Brinkman-Rowell-Dynes model was applied to fit the conductance-voltage plots to calculate the thickness of oxide layers. Junctions with graphene both on bottom and on top were fabricated and their tunneling properties were characterized after exposure to air for weeks to test time stability. Furthermore, the resistances of graphene tunnel junctions with aluminum oxide formed naturally and in an oxygen atmosphere were studied. Our results demonstrate that in-situ aluminum oxide is an effective barrier for graphene tunnel junctions. The methods of barrier formation enable the realization of more tunnel devices and circuits based on graphene.

  14. Stabilized chromium oxide film

    DOEpatents

    Nyaiesh, A.R.; Garwin, E.L.

    1986-08-04

    Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150A are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

  15. Stabilized chromium oxide film

    DOEpatents

    Garwin, Edward L.; Nyaiesh, Ali R.

    1988-01-01

    Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150.ANG. are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

  16. Investigation of Dispersion, Stability, and Tribological Performance of Oil-Based Aluminum Oxide Nanofluids

    DTIC Science & Technology

    2012-01-01

    illustrated a layer of calcium, cerium and oxides as a protective film that protected the surface. The study was repeated by Gu et al., [27...INVESTIGATION OF DISPERSION, STABILITY, AND TRIBOLOGICAL PERFORMANCE OF OIL-BASED ALUMINUM OXIDE NANOFLUIDS THESIS FOR THE...TRIBOLOGICAL PERFORMANCE OF OIL-BASED ALUMINUM OXIDE NANOFLUIDS 5a. CONTRACT NUMBER W56H2V-08-C-0236 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6

  17. Formulation and method for preparing gels comprising hydrous aluminum oxide

    DOEpatents

    Collins, Jack L.

    2014-06-17

    Formulations useful for preparing hydrous aluminum oxide gels contain a metal salt including aluminum, an organic base, and a complexing agent. Methods for preparing gels containing hydrous aluminum oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including aluminum, an organic base, and a complexing agent.

  18. Fast electromigration crack in nanoscale aluminum film

    NASA Astrophysics Data System (ADS)

    Emelyanov, O. A.; Ivanov, I. O.

    2014-08-01

    The current-induced breakage of 20 nm thin aluminum layers deposited onto capacitor grade polypropylene (PP) films is experimentally studied. Biexponential current pulses of different amplitude (10-15 A) and duration (0.1-1 μs) were applied to the samples. Breakage occurred after fast development of electromigrating ˜200 nm-wide cracks with initial propagation velocity of ˜1 m/s under a high current density of ˜1012 A/m2. The cracks stopped when their lengths reached 250-450 μm. This behavior is explained by the balance of electromigration and stress-induced atomic fluxes.

  19. Nanoscale aluminum concaves for light-trapping in organic thin-films

    NASA Astrophysics Data System (ADS)

    Goszczak, Arkadiusz Jarosław; Adam, Jost; Cielecki, Paweł Piotr; Fiutowski, Jacek; Rubahn, Horst-Günter; Madsen, Morten

    2016-07-01

    Anodic aluminum oxide (AAO) templates, fabricated from oxalic acid and phosphoric acid, lead to non-periodic nanoscale concave structures in their underlying aluminum layer, which are investigated for their field-enhancement properties by applying a thin-film polymer coating based laser ablation technique. Local ablation spots, corresponding to field enhancement on the ridge edges of the aluminum concave nanostructures, are observed in surface-covering polymer films, and confirmed with FDTD studies. The field enhancement leads to improved light absorption in the applied polymer layers, which may be used as an efficient method for enhancing the power conversion efficiency of organic solar cells.

  20. Synthesis and characterization of nanoporous anodic oxide film on aluminum in H3PO4 + KMnO4 electrolyte mixture at different anodization conditions

    NASA Astrophysics Data System (ADS)

    Verma, Naveen; Jindal, Jitender; Singh, Krishan Chander; Mari, Bernabe

    2016-04-01

    The micro structural properties of nanoporous anodic oxide film formed in H3PO4 were highly influenced by addition of a low concentration of KMnO4 (0.0005 M) in 1 M H3PO4 solution. The KMnO4 as additive enhanced the growth rate of oxide film formation as well as thickness of pore walls. Furthermore the growth rate was found increased with increase in applied current density. The increase in temperature and lack of stirring during anodization causes the thinness of pore wall which leads to increase in pore volume. With the decrease in concentration of H3PO4 in anodizing electrolyte from 1M to 0.3 M, keeping all other conditions constant, the decrease in porosity was observed. This might be due to the dissolution of aluminium oxide film in highly concentrated acidic solution.

  1. Specific features of aluminum nanoparticle water and wet air oxidation

    SciTech Connect

    Lozhkomoev, Aleksandr S. Glazkova, Elena A. Svarovskaya, Natalia V. Bakina, Olga V. Kazantsev, Sergey O. Lerner, Marat I.

    2015-10-27

    The oxidation processes of the electrically exploded aluminum nanopowders in water and in wet air are examined in the paper. The morphology of the intermediate reaction products of aluminum oxidation has been studied using the transmission electron microscopy. It was shown that the aluminum nanopowder water oxidation causes the formation of the hollow spheres with mesoporous boehmite nanosheets coating. The wedge-like bayerite particles are formed during aluminum nanopowder wet air oxidation.

  2. Improving the Cycling Life of Aluminum and Germanium Thin Films for use as Anodic Materials in Li-Ion Batteries.

    SciTech Connect

    Hudak, Nicholas; Huber, Dale L.; Gulley, Gerald

    2014-09-01

    The cycling of high-capacity electrode materials for lithium-ion batteries results in significant volumetric expansion and contraction, and this leads to mechanical failure of the electrodes. To increase battery performance and reliability, there is a drive towards the use of nanostructured electrode materials and nanoscale surface coatings. As a part of the Visiting Faculty Program (VFP) last summer, we examined the ability of aluminum oxide and gold film surface coatings to improve the mechanical and cycling properties of vapor-deposited aluminum films in lithium-ion batteries. Nanoscale gold coatings resulted in significantly improved cycling behavior for the thinnest aluminum films whereas aluminum oxide coatings did not improve the cycling behavior of the aluminum films. This summer we performed a similar investigation on vapor-deposited germanium, which has an even higher theoretical capacity per unit mass than aluminum. Because the mechanism of lithium-alloying is different for each electrode material, we expected the effects of coating the germanium surface with aluminum oxide or gold to differ significantly from previous observations. Indeed, we found that gold coatings gave only small or negligible improvements in cycling behavior of germanium films, but aluminum oxide (Al2O3) coatings gave significant improvements in cycling over the range of film thicknesses tested.

  3. Aluminum doped zinc oxide for organic photovoltaics

    SciTech Connect

    Murdoch, G. B.; Hinds, S.; Sargent, E. H.; Tsang, S. W.; Mordoukhovski, L.; Lu, Z. H.

    2009-05-25

    Aluminum doped zinc oxide (AZO) was grown via magnetron sputtering as a low-cost alternative to indium tin oxide (ITO) for organic photovoltaics (OPVs). Postdeposition ozone treatment resulted in devices with lower series resistance, increased open-circuit voltage, and power conversion efficiency double that of devices fabricated on untreated AZO. Furthermore, cells fabricated using ozone treated AZO and standard ITO displayed comparable performance.

  4. Oxide-assisted laser surfacing of aluminum

    NASA Astrophysics Data System (ADS)

    Hoepp, E. E.; Kerr, Hugh W.

    1996-04-01

    CO2 laser processing has been carried out on pure aluminum substrates for travel speeds from 0.3 to 6.1 mm/s, using laser powers of about 100 W or 300 W, with various preplaced single or mixed powders including CoO, NiO, SiO2, Fe2O3 or TiO2 usually combined with enough aluminum powder to permit complete reduction of the oxides. The 100 W laser experiments included low, normal and high gravity experiments. The resulting tracks were tested qualitatively for scratch resistance, and examined metallographically. Two types of surfacing were observed; continuous oxide layers produced by melting and an oxidation- reduction reaction of the original oxides with aluminum, and alloying of the substrate by elements reduced by the reaction. Low gravity experiments produced more uniform thicknesses and generally less cracking in the continuous oxides than normal or high gravity experiments. Alloying of the substrate ranged from almost 100% intermetallic layers at low laser powers and low travel speeds to complex mixtures and bands of different phases, depending on the temporal stability of the process, the powder composition and thickness, the laser power and travel speed. Optimization of the process could provide useful wear resistant coatings in a space environment.

  5. Fast electromigration crack in nanoscale aluminum film

    SciTech Connect

    Emelyanov, O. A. Ivanov, I. O.

    2014-08-14

    The current-induced breakage of 20 nm thin aluminum layers deposited onto capacitor grade polypropylene (PP) films is experimentally studied. Biexponential current pulses of different amplitude (10–15 A) and duration (0.1–1 μs) were applied to the samples. Breakage occurred after fast development of electromigrating ∼200 nm-wide cracks with initial propagation velocity of ∼1 m/s under a high current density of ∼10{sup 12 }A/m{sup 2}. The cracks stopped when their lengths reached 250–450 μm. This behavior is explained by the balance of electromigration and stress-induced atomic fluxes.

  6. Engineering titanium and aluminum oxide composites using atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Biluš Abaffy, N.; McCulloch, D. G.; Partridge, J. G.; Evans, P. J.; Triani, G.

    2011-12-01

    Mixed metal oxides provide a convenient means to produce coatings with tailored physical properties. We investigate the possibility of synthesizing novel coatings of mixed titanium and aluminum oxide using atomic layer deposition (ALD). Results show that ALD films were prepared with compositions ranging between Al2O3 and TiO2 having refractive indices between 1.6 and 2.4 (at λ = 550 nm) at low temperature. The microstructure and bonding environment within the films was investigated using electron microscopy and x-ray absorption spectroscopy. The films were amorphous, and the Ti and Al atoms were mixed at the atomic scale. The electrical breakdown characteristics of the films were measured and showed that films with intermediate compositions had poor leakage current properties, believed to be caused by the presence of distorted bonding configurations. This study shows that ALD can be used to deposit high quality thin films with tailored optical properties, particularly suitable for applications in which complex topographies are required.

  7. Microtribological studies of aluminum oxide-based ceramics using a new nanotribometer

    NASA Astrophysics Data System (ADS)

    Dvorak, S. David

    The friction and wear characteristics of sapphire single crystals and aluminum oxide, aluminum nitride, and aluminum oxynitride thin films contacted by sapphire and diamond probes have been explored on the nanometer to micrometer length scale, using applied forces in the micronewton to millinewton range. Tests were performed on a nanotribometer, which is designed specifically to operate in this intermediate force and length scale regime, where very little data are currently available. The nanotribometer incorporates several design features, including 3-axis feedback of the sample position, a position-sensitive PIN photodiode for a large dynamic range of force measurements, and the flexibility to use a variety of cantilever probe types. Reciprocating friction and wear tests using silicon nitride AFM cantilevers, sapphire spheres, and conical diamond tips were performed on polished (r-cut and c-cut) sapphire substrates. The sapphire/sapphire combination served as a model aluminum oxide system and was used to explore the effects of changing ambient conditions and surface roughness effects. Nanoscale friction measurements on sapphire show evidence of single-asperity contact behavior and the importance of adhesion in the nanometer regime. The aluminum oxide, aluminum nitride, and aluminum oxynitride thin films used in this study were grown by two different deposition techniques: electron cyclotron resonance (ECR) oxygen and nitrogen plasma assisted electron beam evaporation of aluminum, and RF magnetron sputtering. The films were grown on epitaxial grade r-cut single crystal sapphire substrates with the substrate either at ambient conditions (50sp°C) or heated to 800sp°C. The stoichiometry and microstructure of the films was characterized in situ with RHEED and XPS. The microstructure of the resulting films ranged from amorphous (for low-temperature growth) to highly-oriented crystalline (for high-temperature growth). The AlOsbxNsby films have a preferred

  8. Heterogeneous reaction of ozone with aluminum oxide

    NASA Technical Reports Server (NTRS)

    Keyser, L. F.

    1976-01-01

    Rates and collision efficiencies for ozone decomposition on aluminum oxide surfaces were determined. Samples were characterized by BET surface area, X-ray diffraction, particle size, and chemical analysis. Collision efficiencies were found to be between 2 times 10 to the -10 power and 2 times 10 to the -9 power. This is many orders of magnitude below the value of 0.000001 to 0.00001 needed for appreciable long-term ozone loss in the stratosphere. An activation energy of 7.2 kcal/mole was found for the heterogeneous reaction between -40 C and 40 C. Effects of pore diffusion, outgassing and treatment of the aluminum oxide with several chemical species were also investigated.

  9. Moisture barrier and chemical corrosion protection of silver-based telescope mirrors using aluminum oxide films by plasma-enhanced atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Fryauf, David M.; Phillips, Andrew C.; Kobayashi, Nobuhiko P.

    2013-09-01

    An urgent demand remains in astronomy for high-reflectivity silver mirrors that can withstand years of exposure in observatory environments. The University of California Observatories Astronomical Coatings Lab has undertaken development of protected silver coatings suitable for telescope mirrors that maintain high reflectivity at wavelengths from 340 nm through the mid-infrared spectrum. We present initial results of an investigation into whether plasma-enhanced atomic layer deposition (PEALD) can produce superior protective layers of transparent dielectrics. Several novel coating recipes have been developed with ion-assisted electron beam deposition (IAEBD) of materials including yttrium fluoride, and oxides of yttrium, hafnium, and titanium. Samples of these mirror coatings were covered with conformal layers of aluminum oxide (AlOx) deposited by PEALD using trimethylaluminum as a metal precursor and oxygen as an oxidant gas activated by remote plasma. Samples of coating recipes with and without PEALD oxide undergo aggressive environmental testing, including high temperature/high humidity (HTHH), in which samples were exposed to an environment of 80% humidity at 80°C for ten days in a simple test set-up. HTHH testing show visible results suggesting that the PEALD oxide offers enhanced robust protection against chemical corrosion and moisture from an accelerated aging environment. Mirror samples are further characterized by reflectivity/absorption and atomic force microscopy before and after deposition of oxide coatings. AlOx is suitable for many applications and has been the initial material choice for this study, although we also tried TiOx and HfOx. Further experimentation based on these initial results is on-going.

  10. Sonolytic desorption of mercury from aluminum oxide.

    PubMed

    He, Ziqi; Traina, Samuel J; Bigham, Jerry M; Weavers, Linda K

    2005-02-15

    As discrete particles and/or as coatings on other mineral surfaces in natural systems, aluminum (hydr)oxides are efficient sinks for Hg(II). Ultrasound at 20 kHz was applied to enhance the desorption of Hg(II) from aluminum oxide particles (5.0 micromol of Hg g(-1)). Results showed that at short times ultrasound enhanced Hg(II) release at pH 4.0 compared to both that from hydrodynamic mixing and that expected on the basis of the Hg(II) sorption isotherm. The higher the input power of sonication, the higher the desorption of Hg(II). However, with longer times, much less desorption occurred by ultrasound than by hydrodynamic mixing, with mass balance measurements demonstrating that the desorbed Hg(II) was resorbed back to the particles. The particles were characterized to explore the mechanism for resorption of Hg(II) by prolonged sonication. No surface area change was observed even though ultrasound dramatically reduced the particle size and changed the surface morphology. Although a decrease in the point of zero charge (PZC) due to sonication was observed, it was excluded as the primary mechanism for Hg(II) resorption. Hg(II) occlusion by aluminum hydroxide precipitation was supported by X-ray photoelectron spectroscopy results and the formation of solutions supersaturated with AI. Experiments on presonicated particles verified the occlusion theory by ruling out the effects of the surface area and PZC.

  11. Nanostructure of aluminum oxide inclusion and formation of hydrogen bubbles in molten aluminum.

    PubMed

    Zeng, Jianmin; Li, Dezhi; Kang, Minglong; He, Huan; Hu, Zhiliu

    2013-10-01

    Hydrogen in molten aluminum is one of the major factors that lead to pore formation in the solidification process of aluminum castings. Previous research showed that aluminum oxide inclusion had a close correlation with the hydrogen content in molten aluminum. Though some researchers thought there must have been a relationship between surface morphology of the inclusion and hydrogen concentration in molten aluminum, very few documents have reported on the surface property of aluminum oxide inclusion. In the present work, AFM (Atomic Force Microscope) was first used to investigate surface morphology of aluminum oxide inclusion in molten aluminum. It was found that there were a large number of nanoscale micropores on the surface of aluminum oxide inclusion. The interior of the micropores was approximated as a tapered shape. These micropores were thought to be helpful to heterogeneous nucleation for hydrogen atoms aggregation because they provided necessary concentration fluctuation and energy undulation for the growth of hydrogen bubbles. Based on the nanostructure observed on the surface of aluminum oxide inclusion, a theoretical model was developed to describe the hydrogen pore formation in aluminum casting under the condition of heterogeneous nucleation.

  12. Low Temperature Film Growth of the Oxides of Zinc, Aluminum, and Vanadium (and Related Systems, Oxides of Gold and Germanium, Nitrides of Aluminum and Tungsten) by Reactive Sputter Deposition.

    DTIC Science & Technology

    1988-02-01

    its surface in an rf half cycle, the target develps a nega- manner, a film is deposited on the substrate. However, high tive self-bias that can be...x-ray dif- fraction using unresolved CuKa radiation. Peak position (29), relative intensity (I), and full width at one half maximum intensity were...fundamental absorption band intensity was equal to one- half its maximum value.[12] The next step in the study involved replacing various amounts of Ne

  13. Optical properties of double layer thin films zinc oxide doping aluminum (ZnO/Al) were deposited on glass substrates by sol gel method spray coating technique

    NASA Astrophysics Data System (ADS)

    Permatasari, Anes; Sutanto, Heri; Marito Siagian, Sinta

    2017-01-01

    Thin films of double layer of ZnO/Al has succeeded in deposition on a glass substrate using sol-gel method and spray coating techniques. Variations of doping Al as much as 2%, 4%, 6% and 8%. ZnO precursor synthesized using zinc acetate dehydrate (Zn(COOCH3)2.2H2O), isopropanol ((CH3)2CHOH) and monoethanolamine (MEA) were stirred using a magnetic stirrer for 45 minutes. ZnO precursor get homogeneous and then added of aluminum nitrate nonahydrate predetermined doping concentration and stirred again for 15 minutes. Deposition solution is done by the spray on a glass substrate and then heated at a temperature of 450°C. A layer of ZnO/Al deposited over the ZnO to produce a thin layer of a double layer. Optical properties layer of ZnO/Al characterized using UV-Vis spectrophotometer. Based on data from UV-Vis absorbance was determined the value of the energy band gap. Pure and dopped layers has different energy due the Al dopping. For pure ZnO layer has energy band gap of 3.347 eV and decreased to 3.09 eV for ZnO layer with Al dopant.

  14. Immobilization of alliinase on porous aluminum oxide.

    PubMed

    Milka, P; Krest, I; Keusgen, M

    2000-08-05

    Membrane filters prepared from porous aluminum oxide (Anopore) were investigated for their potential use as a durable support for enzymes. Alliinase (EC 4.4.1.4) was chosen as a model enzyme for immobilization experiments. To allow for smooth fixation, the enzyme was immobilized indirectly by sugar-lectin binding. Monomolecular layers of the lectin concanavalin A and alliinase were applied by self-assembling processes. As an anchor for these layers, the sugar, mannan, was covalently coupled to the membrane surface. This procedure exhibits several advantages: (i) enzyme immobilization can be carried out under smooth conditions; (ii) immobilization needs little time; and (iii) protein layers may be renewed.

  15. Ester oxidation on an aluminum surface using chemiluminescence

    NASA Technical Reports Server (NTRS)

    Jones, William R., Jr.; Meador, Michael A.; Morales, Wilfredo

    1986-01-01

    The oxidation characteristics of a pure ester (trimethyolpropane triheptanoate) were studied by using a chemiluminescence technique. Tests were run in a thin film microoxidation apparatus with an aluminum alloy catalyst. Conditions included a pure oxygen atmosphere and a temperature range of 176 to 206 C. Results indicated that oxidation of the ester (containing .001 M diphenylanthracene as an intensifier) was accompanied by emission of light. The maximum intensity of light emission was a function of the amount of ester, the concentration of intensifier, and the test temperature. The induction period, or the time to reach one-half of maximum intensity was inversely proportional to test temperature. Decreases in light emission at the later stages of a test were caused by depletion of the intensifier.

  16. Study of Aluminum-doped zinc oxide current spreading layer on P-side up thin-film AlGaInP-based light-emitting diodes by ALD

    NASA Astrophysics Data System (ADS)

    Tseng, Ming-Chun; Chen, Chi-Lu; Lai, Nan-Kai; Wuu, Dong-Sing; Lee, Hsin-Ying; Lin, Yu-Chang; Horng, Ray-Hua

    2015-03-01

    A twice wafer-transfer technique can be used to fabricate high-brightness p-side-up thin-film AlGaInP-based light-emitting diodes (LEDs) with an aluminum-doped zinc oxide (AZO) thin films transparent conductive layer deposited on a GaP window layer. The GaP window layer consist of the two different doping profile, the carbon doped Gap (GaP:C) window layer of 50 nm is on the top of Mg doped GaP window layer of 8 μm. The GaP:C window layer is used to improved the ohmic contact properties of GaP:C/AZO. The AZO with different cycle ratio of Zn:Al (15:1, 20:1 and 25:1) is deposited on GaP:C window layer as current spreading layer by atomic layer deposition. The AZO layer can be used to improve light extraction, which enhances light output power. The output power of p-side-up thin-film AlGaInP LED with an AZO layer of 20:1 cycle ratio has improved up to 19.2 % at injection current of 350 mA, as compared with that of LED without AZO film. The p-side-up thin-film AlGaInP LED with AZO current spreading layer exhibited excellent performance stability, the emission wavelength shift of p-side-up thin-film AlGaInP LED without and with AZO thin film(Zn:Al=20:1) are 17 nm and 3 nm under the injection current increased from 20 mA to 1000mA, respectively. This stability can be attributed to the following factors: 1) Refractive index matching, performed by introducing AZO thin film between the epoxy and the GaP window layer enhances light extraction; and 2) the favorable thermal dissipation of the silicon substrate reduces thermal degradation.

  17. Nitrogen-stabilized aluminum oxide spinel /ALON/

    NASA Astrophysics Data System (ADS)

    Corbin, N. D.; McCauley, J. W.

    1982-10-01

    The fabrication techniques, material properties, and performance features of the nitrogen stabilized aluminum oxide spinel ceramic ALON for structural and optical applications are detailed. ALON has been sintered into a single phase form to produce an isotropic, dense, transparent material. Specimens produced have a Knoop hardness of 1800, an elastic modulus of 46 million psi, a room temperature fracture strength of 45,000 psi, and experience negligible oxidation in air up to 1200 C. The dielectric constant and loss tangent at 10 MHz are 8.56 and 0.0004, respectively, and an IR cutoff has been set at 5.2 microns. The ALON thermal expansion coefficient is 7/1,000,000 per deg C from 25-1000 C. Applications requiring alpha-Al2O3 are foreseen for ALON.

  18. Reactive ion beam deposition of aluminum nitride thin films

    NASA Astrophysics Data System (ADS)

    Bhat, S.; Ashok, S.; Fonash, S. J.; Tongson}, L.

    1985-07-01

    Aluminum nitride thin films have been prepared at room temperature by reactive ion beam sputtering for potential use as a passivant and diffusion/anneal cap in compound semiconductor technology. The electrical and optical pro-perties of these films have been studied along with the in-fluence of thermal annealing on the material characteristics. The quality of the films has also been found to improve in the presence of atomic hydrogen during the deposition.

  19. Alkaline oxide conversion coatings for aluminum alloys

    SciTech Connect

    Buchheit, R.G.

    1996-02-01

    Three related conversion coating methods are described that are based on film formation which occurs when aluminum alloys are exposed to alkaline Li salt solutions. Representative examples of the processing methods, resulting coating structure, composition and morphology are presented. The corrosion resistance of these coatings to aerated 0.5 M NaCl solution has been evaluated as a function of total processing time using electrochemical impedance spectroscopy (EIS). This evaluation shows that excellent corrosion resistance can be uniformly achieved using no more than 20 minutes of process time for 6061-T6. Using current methods a minimum of 80 minutes of process time is required to get marginally acceptable corrosion resistance for 2024-T3. Longer processing times are required to achieve uniformly good corrosion resistance.

  20. Lithography-free transmission filters at ultraviolet frequencies using ultra-thin aluminum films

    NASA Astrophysics Data System (ADS)

    Li, Zhongyang; Butun, Serkan; Aydin, Koray

    2016-06-01

    Aluminum allows for significant plasmon responses in ultraviolet (UV) regime of spectrum, where conventional plasmonic materials such as silver and gold lack plasmonic behavior due to their inherent dissipative limitation from lower plasmon frequency and inter-band transition. Such UV plasmonic resonance based on aluminum nanostructures could be challenging due to the smaller feature size of nanoscale resonator and remarkable sensitivity to oxidization. Here we theoretically and experimentally demonstrate lithography-free transmission filters using triple layers of continuous ultra-thin Al and dielectric films. Our proposed transmission filter is a triple-layer Fabry-Perot cavity and operates from 2.5 to 5.5 eV with bandwidth down to 0.5 eV and transmission amplitude up to 50%. Such flat Al ultra-thin film coatings suggest the use of aluminum as low-cost UV filters and UV optoelectronics as well as structural coloring applications.

  1. Combined in situ PM-IRRAS/QCM studies of water adsorption on plasma modified aluminum oxide/aluminum substrates

    NASA Astrophysics Data System (ADS)

    Giner, Ignacio; Maxisch, Michael; Kunze, Christian; Grundmeier, Guido

    2013-10-01

    Water adsorption on plasma modified oxyhydroxide covered aluminum surfaces was analyzed by means of a set-up combining in situ photoelastic modulated infrared reflection absorption spectroscopy (PM-IRRAS) and quartz crystal microbalance (QCM) in a low-temperature plasma cell. The chemical structure of the surface before and after the plasma treatment was moreover characterized by means of X-ray photoelectron spectroscopy (XPS) analysis. The surface chemistry of oxide covered aluminum was modified by oxidative and reductive low-temperature plasma pre-treatments. The Ar-plasma treatment reduced the surface hydroxyl density and effectively removed adsorbed organic contaminations. Surface modification by means of a water plasma treatment led to an increased surface hydroxyl density as well as an increase of the thickness of the native oxide film. The adsorption of water at atmospheric pressures on plasma modified aluminum surfaces led to a superimposition of reversible water layer adsorption and a simultaneous increase of the oxyhydroxide film thickness as a result of a chemisorption process. The amount of physisorbed water increased with the surface hydroxyl density whereas the chemisorption process was most significant for the surface after Ar-plasma treatment and almost negligible for the already water plasma treated surface.

  2. High Temperature Annealing Studies on the Piezoelectric Properties of Thin Aluminum Nitride Films

    SciTech Connect

    Farrell, R.; Pagan, V.R.; Kabulski, A.; Kuchibhatla, S.; Harman, J.; Kasarla, K.R.; Rodak, L.E.; Hensel, J.P.; Famouri, P.; Korakakis, D.

    2008-01-01

    A Rapid Thermal Annealing (RTA) system was used to anneal sputtered and MOVPE-grown Aluminum Nitride (AlN) thin films at temperatures up to 1000°C in ambient and controlled environments. According to Energy Dispersive X-Ray Analysis (EDAX), the films annealed in an ambient environment rapidly oxidize after five minutes at 1000°C. Below 1000°C the films oxidized linearly as a function of annealing temperature which is consistent with what has been reported in literature [1]. Laser Doppler Vibrometry (LDV) was used to measure the piezoelectric coefficient, d33, of these films. Films annealed in an ambient environment had a weak piezoelectric response indicating that oxidation on the surface of the film reduces the value of d33. A high temperature furnace has been built that is capable of taking in-situ measurements of the piezoelectric response of AlN films. In-situ d33 measurements are recorded up to 300°C for both sputtered and MOVPE-grown AlN thin films. The measured piezoelectric response appears to increase with temperature up to 300°C possibly due to stress in the film.

  3. Metal oxide films on metal

    DOEpatents

    Wu, Xin D.; Tiwari, Prabhat

    1995-01-01

    A structure including a thin film of a conductive alkaline earth metal oxide selected from the group consisting of strontium ruthenium trioxide, calcium ruthenium trioxide, barium ruthenium trioxide, lanthanum-strontium cobalt oxide or mixed alkaline earth ruthenium trioxides thereof upon a thin film of a noble metal such as platinum is provided.

  4. Graded-index films using aluminum oxynitrides

    NASA Astrophysics Data System (ADS)

    Placido, Francis; Russell, John; Gou, Zhenhui

    1996-08-01

    High quality coatings of aluminium oxynitrides have been deposited by reactive RF sputtering of aluminium in argon/oxygen/nitrogen atmospheres. Graded-index films in which the refractive index changes continuously with thickness over the range 1.6-2.0 have been produced by varying the oxygen and nitrogen content of the growing film. Computer control of the gas flow rates has allowed the reproducible production of laser rejection filters having optical densities greater than 4 and rejection wavelengths which can be chosen from < 300 to > 1100 nm. Scanning electron microscopy has shown that films when broken, tend to fracture preferentially at one particular composition. Depth profiling chemical analysis of the films has been carried our using x-ray photoelectron spectroscopy, showing clearly that the desired sinusoidal composition variations with depth has been achieved in these films.

  5. Oxidation of fine aluminum powders with water and air

    NASA Astrophysics Data System (ADS)

    Antipina, S. A.; Zmanovskii, S. V.; Gromov, A. A.; Konovalov, A. S.

    2017-01-01

    Fine aluminum powders (RA20-RA60 grades, SUAL-PM) with specific surface area from 0.37 to 0.73 m2/g and high aluminum contents (95-98 wt %) are studied. The powders are found to be waterwettable without additions of surfactants and characterized by high rates of gas liberation in reacting with a calcium hydroxide solution under normal conditions. All RA20-RA60 powders are shown to be highly reactive upon oxidation with air and close to aluminum nanopowders in the parameters of their activity when heated in air. Their stability in water could prevent active (metallic) aluminum losses during their storage.

  6. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...), not more than 30 parts per million. Arsenic (as As), not more than 3 parts per million. Total oxides of aluminum, chromium, and cobalt not less than 97 percent. Lead and arsenic shall be determined...

  7. Radiolysis of water with aluminum oxide surfaces

    NASA Astrophysics Data System (ADS)

    Reiff, Sarah C.; LaVerne, Jay A.

    2017-02-01

    Aluminum oxide, Al2O3, nanoparticles with water were irradiated with γ-rays and 5 MeV He ions followed by the determination of the production of molecular hydrogen, H2, and characterization of changes in the particle surface. Surface analysis techniques included: diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), nitrogen absorption with the Brunauer - Emmett - Teller (BET) methodology for surface area determination, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Production of H2 by γ-ray radiolysis was determined for samples with adsorbed water and for Al2O3 - water slurries. For Al2O3 samples with adsorbed water, the radiation chemical yield of H2 was measured as 80±20 molecules/100 eV (1 molecule/100 eV=1.04×10-7 mol/J). The yield of H2 was observed to decrease as the amount of water present in the Al2O3 - water slurries increased. Surface studies indicated that the α-phase Al2O3 samples changed phase following irradiation by He ions, and that the oxyhydroxide layer, present on the pristine sample, is removed by γ-ray and He ion irradiation.

  8. Modeling the Shock Ignition of a Copper Oxide Aluminum Thermite

    NASA Astrophysics Data System (ADS)

    Lee, Kibaek; Stewart, D. Scott; Clemenson, Michael; Glumac, Nick; Murzyn, Christopher

    2015-06-01

    An experimental ``striker confinement'' shock compression test was developed in the Glumac-group at the University of Illinois to study ignition and reaction in composite reactive materials. These include thermitic and intermetallic reactive powders. The test places a sample of materials such as a thermite mixture of copper oxide and aluminum powders that are initially compressed to about 80 percent full density. Two RP-80 detonators simultaneously push steel bars into reactive material and the resulting compression causes shock compaction of the material and rapid heating. At that point one observes significant reaction and propagation of fronts. But the fronts are peculiar in that they are comprised of reactive events that can be traced to the reaction/diffusion of the initially separated reactants of copper oxide and aluminum that react at their mutual interfaces that nominally make copper liquid and aluminum oxide products. We discuss our model of the shock ignition of the copper oxide aluminum thermite in the context of the striker experiment and how a Gibbs formulation model, that includes multi-components for liquid and solid phases of aluminum, copper oxide, copper and aluminum oxide can predict the events observed at the particle scale in the experiments. Supported by HDTRA1-10-1-0020 (DTRA), N000014-12-1-0555 (ONR).

  9. Modeling the ignition of a copper oxide aluminum thermite

    NASA Astrophysics Data System (ADS)

    Lee, Kibaek; Stewart, D. Scott; Clemenson, Michael; Glumac, Nick; Murzyn, Christopher

    2017-01-01

    An experimental "striker confinement" shock compression experiment was developed in the Glumac-group at the University of Illinois to study ignition and reaction in composite reactive materials. These include thermitic and intermetallic reactive powders. Sample of materials such as a thermite mixture of copper oxide and aluminum powders are initially compressed to about 80 percent full density. Two RP-80 detonators simultaneously push steel bars into the reactive material and the resulting compression causes shock compaction of the material and rapid heating. At that point one observes significant reaction and propagation of fronts. But the fronts are peculiar in that they are comprised of reactive events that can be traced to the reaction of the initially separated reactants of copper oxide and aluminum that react at their mutual interfaces, that nominally make copper liquid and aluminum oxide products. We discuss our model of the ignition of the copper oxide aluminum thermite in the context of the striker experiment and how a Gibbs formulation model [1], that includes multi-components for liquid and solid phases of aluminum, copper oxide, copper and aluminum oxide, can predict the events observed at the particle scale in the experiments.

  10. Fabrication and characterization of conductive anodic aluminum oxide substrates

    NASA Astrophysics Data System (ADS)

    Altuntas, Sevde; Buyukserin, Fatih

    2014-11-01

    Biomaterials that allow the utilization of electrical, chemical and topographic cues for improved neuron-material interaction and neural regeneration hold great promise for nerve tissue engineering applications. The nature of anodic aluminum oxide (AAO) membranes intrinsically provides delicate control over topographic and chemical cues for enhanced cell interaction; however their use in nerve regeneration is still very limited. Herein, we report the fabrication and characterization of conductive AAO (CAAO) surfaces for the ultimate goal of integrating electrical cues for improved nerve tissue behavior on the nanoporous substrate material. Parafilm was used as a protecting polymer film, for the first time, in order to obtain large area (50 cm2) free-standing AAO membranes. Carbon (C) was then deposited on the AAO surface via sputtering. Morphological characterization of the CAAO surfaces revealed that the pores remain open after the deposition process. The presence of C on the material surface and inside the nanopores was confirmed by XPS and EDX studies. Furthermore, I-V curves of the surface were used to extract surface resistance values and conductive AFM demonstrated that current signals can only be achieved where conductive C layer is present. Finally, novel nanoporous C films with controllable pore diameters and one dimensional (1-D) C nanostructures were obtained by the dissolution of the template AAO substrate.

  11. Methods for both coating a substrate with aluminum oxide and infusing the substrate with elemental aluminum

    SciTech Connect

    Choi, Jung-Pyung; Weil, Kenneth Scott

    2016-11-01

    Methods of aluminizing the surface of a metal substrate. The methods of the present invention do not require establishment of a vacuum or a reducing atmosphere, as is typically necessary. Accordingly, aluminization can occur in the presence of oxygen, which greatly simplifies and reduces processing costs by allowing deposition of the aluminum coating to be performed, for example, in air. Embodiments of the present invention can be characterized by applying a slurry that includes a binder and powder granules containing aluminum to the metal substrate surface. Then, in a combined step, a portion of the aluminum is diffused into the substrate and a portion of the aluminum is oxidized by heating the slurry to a temperature greater than the melting point of the aluminum in an oxygen-containing atmosphere.

  12. Microstructure/electrical Property Correlations for Yttrium BARIUM(2) COPPER(3) OXYGEN(7-X)/BARRIER Layer Films Deposited on Aluminum Oxide, Silicon, and Yttria - Zirconia Substrates

    NASA Astrophysics Data System (ADS)

    Mueller, Carl Henry

    YBa_2Cu_3O_ {7-x} and barrier layer films were deposited on single-crystal silicon (Si), Al_2O _3, yittria-stabilized zirconia (Y-ZrO _2), SrTiO_3, and LaAlO_3 substrates. A pulsed laser deposition process was used to deposit the films at a substrate temperature of 730-750^circC, and the films were cooled in an oxygen ambient. The films were characterized using resistance versus temperature, critical current density (J_{c}), x-ray diffraction (XRD), scanning electron microscopy (SEM), Auger electron spectroscopy (AES), and Raman spectroscopy. Growth of barrier layers on Si and Al_2O_3 substrates prior to the superconductor suppressed chemical interdiffusion between the superconductor and substrate. For (1102) Al_2O _3, the best barrier layer was a SrTiO _3 film deposited at 200 mTorr of oxygen. The YBa_2Cu_3O_{7 -x} film had a zero resistance temperature of 83^circK, and the J _{c} was 2.5 times 10^6 amps/cm ^2 at 4.5^circ K. The surface resistance was 10^ {-2} ohms at 36 gigahertz. On silicon substrates, YBa_2Cu _3O_{7-x} degradation is aggrevated by thermal stresses created by the difference in thermal expansion coefficients between YBa_2Cu_3O_{7-x} and Si (13.2 versus 3.8 times 10 ^{-6}/^ circC, respectively), which causes microcracking in the YBa_2Cu_3O_ {7-x} films. Cracking and interdiffusion were minimized by depositing a YAlO_3 barrier layer prior to YBa_2Cu _3O_{7-x}. The thermal stresses were relieved by viscoelastic relaxation in the YBa_2Cu_3O_{7-x} film, and the T_0 was 78 ^circK. The J_{c} values of YBa_2Cu_3O_ {7-x} films on Y-ZrO_2 substrates were increased by depositing Y-ZrO _2 or Y_2O_3 barrier layers. YBa_2Cu _3O_{7-x}/Y_2O_3 films on Y-ZrO_2 substrates had J_{c} values of 9 times 10^5 and 1 times 10^7 amps/cm^2 at 77 and 4.5 ^circK. The J_{ c} of YBa_2Cu _3O_{7-x} films deposited on a Y-ZrO_2 substrate without a barrier layer was 6.8 times 10 ^3 amps/cm^2 at 4.5 ^circK. The higher J _{c} values were attributed to pinning of the magnetic flux by

  13. Thermo-physical characteristics of nickel-coated aluminum powder as a function of particle size and oxidant

    NASA Astrophysics Data System (ADS)

    Lee, Sanghyup; Noh, Kwanyoung; Lim, Jihwan; Yoon, Woongsup

    2016-10-01

    Aluminum particles 15-25 µm in size are widely used in fuel propellants and underwater propulsion systems in national defense research. However, these particles are covered with an aluminum oxide film, which has a high melting point, so ignition is difficult. To improve the ignitability of high-energy aluminum powder and to understand the reaction phenomenon as a function of particle size(15-25 µm, 74-105 µm, and 2.38 mm) and oxidizer(air, CO2, and argon), the natural oxide films are chemically removed. The particles are then coated with nickel using an electro-less method. The degree of nickel deposition is confirmed qualitatively and quantitatively through surface analysis using scanning electron microscopy/energy dispersive spectroscopy. To characterize the nickel coatings, elemental analysis is also conducted by using X-ray diffraction. Thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) enable comparisons between the uncoated and coated aluminum, and the reaction process are investigated through fine structural analysis of the particle surfaces and cross sections. There are little difference in reactivity as a function of oxidant type. However, a strong exothermic reaction in the smaller nickel-coated aluminum particles near the melting point of aluminum accelerates the reaction of the smaller particles. Explanation of the reactivity of the nickel-coated aluminum depending on the particle sizes is attempted.

  14. Deposition and characterization of silicon thin-films by aluminum-induced crystallization

    NASA Astrophysics Data System (ADS)

    Ebil, Ozgenc

    Polycrystalline silicon (poly-Si) as a thin-film solar cell material could have major advantages compared to non-silicon thin-film technologies. In theory, thin-film poly-Si may retain the performance and stability of c-Si while taking advantage of established manufacturing techniques. However, poly-Si films deposited onto foreign substrates at low temperatures typically have an average grain size of 10--50 nm. Such a grain structure presents a potential problem for device performance since it introduces an excessive number of grain boundaries which, if left unpassivated, lead to poor solar cell properties. Therefore, for optimum device performance, the grain size of the poly-Si film should be at least comparable to the thickness of the films. For this project, the objectives were the deposition of poly-Si thin-films with 2--5 mum grain size on glass substrates using in-situ and conventional aluminum-induced crystallization (AIC) and the development of a model for AIC process. In-situ AIC experiments were performed using Hot-Wire Chemical Vapor Deposition (HWCVD) both above and below the eutectic temperature (577°C) of Si-Al binary system. Conventional AIC experiments were performed using a-Si layers deposited on aluminum coated glass substrates by Electron-beam deposition, Plasma Enhanced Chemical Vapor Deposition (PECVD) and HWCVD. Continuous poly-Si films with an average grain size of 10 mum on glass substrates were achieved by both in-situ and conventional aluminum-induced crystallization of Si below eutectic temperature. The grain size was determined by three factors; the grain structure of Al layer, the nature of the interfacial oxide, and crystallization temperature. The interface oxide was found to be crucial for AIC process but not necessary for crystallization itself. The characterization of interfacial oxide layer formed on Al films revealed a bilayer structure containing Al2O3 and Al(OH)3 . The effective activation energy for AIC process was determined

  15. BONDING ALUMINUM METALS

    DOEpatents

    Noland, R.A.; Walker, D.E.

    1961-06-13

    A process is given for bonding aluminum to aluminum. Silicon powder is applied to at least one of the two surfaces of the two elements to be bonded, the two elements are assembled and rubbed against each other at room temperature whereby any oxide film is ruptured by the silicon crystals in the interface; thereafter heat and pressure are applied whereby an aluminum-silicon alloy is formed, squeezed out from the interface together with any oxide film, and the elements are bonded.

  16. Sub-surface oxide features at the aluminum-sapphire interface after low temperature annealing

    NASA Astrophysics Data System (ADS)

    Dutta, Sreya

    This work focuses on the formation of sub-surface oxide features that form at the aluminum-sapphire interface during a low temperature heat-treatment. The features consist of two parts, stable alpha-alumina ridges on the substrate, and faceted pyramidal structures composed of thin, low-temperature oxide shells that are bounded by the ridges. It is surprising to observe the formation of thermodynamically stable alpha-alumina at a low temperature. The ridges are epitaxial with the (0001) sapphire substrate and the overlying metal. The pyramidal features resemble closely the Wulff shape in aluminum. Experiments show that these features are underlying the annealing hillocks. This work is a detailed study of such oxide interfacial features associated with hollow hillocks. At the annealing temperatures (below the melting point of aluminum), the aluminum thin film is subjected to compressive stresses arising from the thermal expansion coefficient mismatch and this is aided by dewetting at the aluminum-sapphire interface. Creep cavitation and grain boundary sliding are postulated to help in the cavity formation. Annealing holes are also observed in the thin films. Two different types of holes are seen: dendritic branched holes and hexagonal faceted holes (drums). At lower temperature and thickness, dendritic holes are seen to be formed at the grain boundaries. The drums form within the grains at higher temperatures and in thicker films. The drums have a surface oxide layer suspended on the top. It is postulated that clustering of vacancies due to the presence of irregularities, defects, and dislocations at the interface as well as dewetting causes the nucleation of the drums at the interface. Numerous hillock-hole couples were seen. Thinning of the metal in areas near the hillocks could possibly aid in the hole formation process. It is speculated that the hole growth occurred during the cooling stage when the film was subjected to tensile stresses. Another interesting

  17. Spatial atomic layer deposition on flexible porous substrates: ZnO on anodic aluminum oxide films and Al{sub 2}O{sub 3} on Li ion battery electrodes

    SciTech Connect

    Sharma, Kashish; Routkevitch, Dmitri; Varaksa, Natalia; George, Steven M.

    2016-01-15

    Spatial atomic layer deposition (S-ALD) was examined on flexible porous substrates utilizing a rotating cylinder reactor to perform the S-ALD. S-ALD was first explored on flexible polyethylene terephthalate polymer substrates to obtain S-ALD growth rates on flat surfaces. ZnO ALD with diethylzinc and ozone as the reactants at 50 °C was the model S-ALD system. ZnO S-ALD was then performed on nanoporous flexible anodic aluminum oxide (AAO) films. ZnO S-ALD in porous substrates depends on the pore diameter, pore aspect ratio, and reactant exposure time that define the gas transport. To evaluate these parameters, the Zn coverage profiles in the pores of the AAO films were measured using energy dispersive spectroscopy (EDS). EDS measurements were conducted for different reaction conditions and AAO pore geometries. Substrate speeds and reactant pulse durations were defined by rotating cylinder rates of 10, 100, and 200 revolutions per minute (RPM). AAO pore diameters of 10, 25, 50, and 100 nm were utilized with a pore length of 25 μm. Uniform Zn coverage profiles were obtained at 10 RPM and pore diameters of 100 nm. The Zn coverage was less uniform at higher RPM values and smaller pore diameters. These results indicate that S-ALD into porous substrates is feasible under certain reaction conditions. S-ALD was then performed on porous Li ion battery electrodes to test S-ALD on a technologically important porous substrate. Li{sub 0.20}Mn{sub 0.54}Ni{sub 0.13}Co{sub 0.13}O{sub 2} electrodes on flexible metal foil were coated with Al{sub 2}O{sub 3} using 2–5 Al{sub 2}O{sub 3} ALD cycles. The Al{sub 2}O{sub 3} ALD was performed in the S-ALD reactor at a rotating cylinder rate of 10 RPM using trimethylaluminum and ozone as the reactants at 50 °C. The capacity of the electrodes was then tested versus number of charge–discharge cycles. These measurements revealed that the Al{sub 2}O{sub 3} S-ALD coating on the electrodes enhanced the capacity stability. This S

  18. Oxide Films for RF Applications

    DTIC Science & Technology

    2008-07-01

    structured thin film superlattices of (AEO)m( TiO2 )n - type with varying m and n numbers in order to generate a homologous series of materials having...mechanisms in MBE oxide films The proposed goal was to identify, isolate, and reduce sources of loss in thin film dielectrics. It is important to note...that the loss in bulk single crystals is often orders of magnitude below that of their thin film counterparts. It is believed that defects in thin

  19. Bottom-Up Preparation of Ultrathin 2D Aluminum Oxide Nanosheets by Duplicating Graphene Oxide.

    PubMed

    Huang, Zhifeng; Zhou, Anan; Wu, Jifeng; Chen, Yunqiang; Lan, Xiaoli; Bai, Hua; Li, Lei

    2016-02-24

    2D ultrathin aluminum oxide (2D-Al2O3) nanosheets are prepared by duplicating graphene oxide. An amorphous precursor of the hydroxide of aluminum is first deposited onto graphene oxide sheets, which are then converted into 2D-Al2 O3 nanosheets by calcination, while the graphene oxide is removed. The 2D-Al2O3 nanosheets have a large specific surface area and a superior adsorption capacity to fluoride ions.

  20. Self-ordering behavior of nanoporous anodic aluminum oxide (AAO) in malonic acid anodization

    NASA Astrophysics Data System (ADS)

    Lee, W.; Nielsch, K.; Gösele, U.

    2007-11-01

    The self-ordering behavior of anodic aluminum oxide (AAO) has been investigated for anodization of aluminum in malonic acid (H4C3O4) solution. In the present study it is found that a porous oxide layer formed on the surface of aluminum can effectively suppress catastrophic local events (such as breakdown of the oxide film and plastic deformation of the aluminum substrate), and enables stable fast anodic oxidation under a high electric field of 110-140 V and ~100 mA cm-2. Studies on the self-ordering behavior of AAO indicated that the cell homogeneity of AAO increases dramatically as the anodization voltage gets higher than 120 V. Highly ordered AAO with a hexagonal arrangement of the nanopores could be obtained in a voltage range 125-140 V. The current density (i.e., the electric field strength (E) at the bottom of a pore) is an important parameter governing the self-ordering of the nanopores as well as the interpore distance (Dint) for a given anodization potential (U) during malonic acid anodization.

  1. Hybrid pulse anodization for the fabrication of porous anodic alumina films from commercial purity (99%) aluminum at room temperature.

    PubMed

    Chung, C K; Zhou, R X; Liu, T Y; Chang, W T

    2009-02-04

    Most porous anodic alumina (PAA) or anodic aluminum oxide (AAO) films are fabricated using the potentiostatic method from high-purity (99.999%) aluminum films at a low temperature of approximately 0-10 degrees C to avoid dissolution effects at room temperature (RT). In this study, we have demonstrated the fabrication of PAA film from commercial purity (99%) aluminum at RT using a hybrid pulse technique which combines pulse reverse and pulse voltages for the two-step anodization. The reaction mechanism is investigated by the real-time monitoring of current. A possible mechanism of hybrid pulse anodization is proposed for the formation of pronounced nanoporous film at RT. The structure and morphology of the anodic films were greatly influenced by the duration of anodization and the type of voltage. The best result was obtained by first applying pulse reverse voltage and then pulse voltage. The first pulse reverse anodization step was used to form new small cells and pre-texture concave aluminum as a self-assembled mask while the second pulse anodization step was for the resulting PAA film. The diameter of the nanopores in the arrays could reach 30-60 nm.

  2. Fabrication of FePt networks by porous anodic aluminum oxide

    NASA Astrophysics Data System (ADS)

    Huang, Yen-Chun; Hsiao, Ju-Cheng; Liu, I.-Yun; Wang, Liang-Wei; Liao, Jung-Wei; Lai, Chih-Huang

    2012-04-01

    It is demonstrated that the large-area FePt network nanostructures with strong perpendicular anisotropy can be obtained by growing the mask of porous anodic aluminum oxide (AAO) directly on the L10-FePt films and subsequent plasma etching. The aspect ratio of the AAO mask is critical to achieve well-organized FePt networks. The out-of-plane coercivity of FePt networks is enhanced by 20% compared to that of the FePt film, due to the domain wall pinning effects imposed by the presence of pores.

  3. Analysis of peel strength of consisting of an aluminum sheet, anodic aluminum oxide and a copper foil laminate composite

    NASA Astrophysics Data System (ADS)

    Shin, Hyeong-Won; Lee, Hyo-Soo; Jung, Seung-Boo

    2017-01-01

    Laminate composites consisting of an aluminum sheet, anodic aluminum oxide, and copper foil have been used as heat-spreader materials for high-power light-emitting diodes (LEDs). These composites are comparable to the conventional structure comprising an aluminum sheet, epoxy adhesives, and copper foil. The peel strength between the copper foil and anodic aluminum oxide should be more than 1.0 kgf/cm in order to be applied in high-power LED products. We investigated the effect of the anodic aluminum oxide morphology and heat-treatment conditions on the peel strength of the composites. We formed an anodic aluminum oxide layer on a 99.999% pure aluminum sheet using electrochemical anodization. A Ti/Cu seed layer was formed using the sputtering direct bonding copper process in order to form a copper circuit layer on the anodic aluminum oxide layer by electroplating. The developed heat spreader, composed of an aluminum layer, anodic aluminum oxide, and a copper circuit layer, showed peel strengths ranging from 1.05 to 3.45 kgf/cm, which is very suitable for high-power LED applications.

  4. Poly-crystalline thin-film by aluminum induced crystallization on aluminum nitride substrate

    NASA Astrophysics Data System (ADS)

    Bhopal, Muhammad Fahad; Lee, Doo Won; Lee, Soo Hong

    2016-09-01

    Thin-film polycrystalline silicon ( pc-Si) on foreign (non-silicon) substrates has been researched by various research groups for the production of photovoltaic cells. High quality pc-Si deposition on foreign substrates with superior optical properties is considered to be the main hurdle in cell fabrication. Metal induced crystallization (MIC) is one of the renowned techniques used to produce this quality of material. In the current study, an aluminum induced crystallization (AIC) method was adopted to produce pc-Si thin-film on aluminum nitride (AlN) substrate by a seed layer approach. Aluminum and a-Si layer were deposited using an e-beam evaporator. Various annealing conditions were used in order to investigate the AIC grown pc-Si seed layers for process optimization. The effect of thermal annealing on grain size, defects preferentially crystallographic orientation of the grains were analyzed. Surface morphology was studied using an optical microscope. Poly-silicon film with a crystallinity fraction between 95-100% and an FWHM between 5-6 cm-1 is achievable at low temperatures and for short time intervals. A grain size of about 10 micron can be obtained at a low deposition rate on an AIN substrate. Similarly, Focused ion beam (FIB) also showed that at 425 °C sample B and at 400 °C sample A were fully crystallized. The crystalline quality of pc-Si was evaluated using μ-Raman spectroscopy as a function of annealed conditions and Grazing incidence X-ray diffraction (GIXRD) was used to determine the phase direction of the pc-Si layer. The current study implicates that a poly-silicon layer with good crystallographic orientation and crystallinity fraction is achievable on AIN substrate at low temperatures and short time frames.

  5. Colloidal infrared reflective and transparent conductive aluminum-doped zinc oxide nanocrystals

    DOEpatents

    Buonsanti, Raffaella; Milliron, Delia J

    2015-02-24

    The present invention provides a method of preparing aluminum-doped zinc oxide (AZO) nanocrystals. In an exemplary embodiment, the method includes (1) injecting a precursor mixture of a zinc precursor, an aluminum precursor, an amine, and a fatty acid in a solution of a vicinal diol in a non-coordinating solvent, thereby resulting in a reaction mixture, (2) precipitating the nanocrystals from the reaction mixture, thereby resulting in a final precipitate, and (3) dissolving the final precipitate in an apolar solvent. The present invention also provides a dispersion. In an exemplary embodiment, the dispersion includes (1) nanocrystals that are well separated from each other, where the nanocrystals are coated with surfactants and (2) an apolar solvent where the nanocrystals are suspended in the apolar solvent. The present invention also provides a film. In an exemplary embodiment, the film includes (1) a substrate and (2) nanocrystals that are evenly distributed on the substrate.

  6. Oxide Films RF Applications

    DTIC Science & Technology

    2006-06-01

    different stabilities and properties . Certain applications, such as integrated dielectrics or photoelectrochemical cells, require thin films of TiO2 that...interesting dielectric properties . Another is that the (001) plane of anatase TiO2 is one of the two main layers stacked along the (100) direction in...Public Release 13. SUPPLEMENTARY NOTES .bDib ibuUl I U 1 iited 14. ABSTRACT TiO2 films were grown using a reactive molecular beam epitaxy system

  7. Ultraviolet optical properties of aluminum fluoride thin films deposited by atomic layer deposition

    SciTech Connect

    Hennessy, John Jewell, April D.; Balasubramanian, Kunjithapatham; Nikzad, Shouleh

    2016-01-15

    Aluminum fluoride (AlF{sub 3}) is a low refractive index material with promising optical applications for ultraviolet (UV) wavelengths. An atomic layer deposition process using trimethylaluminum and anhydrous hydrogen fluoride has been developed for the deposition of AlF{sub 3} at substrate temperatures between 100 and 200 °C. This low temperature process has resulted in thin films with UV-optical properties that have been characterized by ellipsometric and reflection/transmission measurements at wavelengths down to 200 nm. The optical loss for 93 nm thick films deposited at 100 °C was measured to be less than 0.2% from visible wavelengths down to 200 nm, and additional microstructural characterization demonstrates that the films are amorphous with moderate tensile stress of 42–105 MPa as deposited on silicon substrates. X-ray photoelectron spectroscopy analysis shows no signature of residual aluminum oxide components making these films good candidates for a variety of applications at even shorter UV wavelengths.

  8. Effects of aluminum and zirconia contents on the reaction bonded aluminum oxide process

    NASA Astrophysics Data System (ADS)

    Sheedy, Paul Martin

    The effects of aluminum and ZrO2 contents on the reaction and sintering of reaction bonded aluminum oxide (RBAO) were investigated. It was apparent that ZrO2-containing RBAO powders with higher initial aluminum contents (>45 vol%) were increasingly more difficult to react and sinter. During oxidation in air, samples often underwent a self-propagating high-temperature synthesis (SHS) reaction which led to catastrophic failure. This reaction and cracking behavior was more pronounced with increasing aluminum and ZrO2 contents of the powders. Subsequently, it was shown that the SHS reaction was actually two combustion phenomena: a thermal explosion reaction on the surface of the sample between aluminum and oxygen, which (in ZrO2-containing samples) triggered a self propagating aluminothermic reduction of ZrO2, forming Al2O3 and Al 3Zr. Therefore, methods for controlling the rate of the initial oxidation reaction were effective since both SHS reactions were prevented. Despite the use of controlled firing, initial samples with increasing aluminum contents proved difficult to densify. It was found that in all RBAO samples (regardless of ZrO2 content), the reactively formed Al 2O3 underwent the gamma to alpha-Al2O 3 transformation, which resulted in the development of a vermicular microstructure. In ZrO2-containing RBAO samples, this transformation was inhibited and occurred concurrently with the start of densification. In addition, the start of bulk shrinkage in these samples was delayed and the densification rates were decreased in comparison to samples without ZrO 2. This ultimately resulted in a decrease in the limiting density to which ZrO2-containing RBAO samples could be sintered. Surprisingly, in samples without ZrO2, increasing the aluminum content did not appear to have any effects upon the densification behavior of RBAO. In examining RBAO samples with similar aluminum contents but increasing ZrO2 contents, it became apparent that the grain growth inhibiting

  9. Drilling of aluminum and copper films with femtosecond double-pulse laser

    NASA Astrophysics Data System (ADS)

    Wang, Qinxin; Luo, Sizuo; Chen, Zhou; Qi, Hongxia; Deng, Jiannan; Hu, Zhan

    2016-06-01

    Aluminum and copper films are drilled with femtosecond double-pulse laser. The double-pulse delay is scanned from -75 ps to 90 ps. The drilling process is monitored by recording the light transmitted through the sample, and the morphology of the drilled holes is analyzed by optical microscopy. It is found that, the breakthrough time, the hole evolution during drilling, the redeposited material, the diameters of the redeposited area and the hole, change as functions of double-pulse delay, and are different for the two metals. Along the double-pulse delay axis, three different time constants are observed, a slow one of a few tens of picoseconds, a fast one of a few picoseconds, and an oscillation pattern. Results are discussed based on the mechanisms of plasma shielding, electron-phonon coupling, strong coupling of laser with liquid phase, oxidation of aluminum, laser induced temperature and pressure oscillations, and the atomization of plume particles.

  10. Use of aluminum as an oxidation barrier for titanium

    NASA Technical Reports Server (NTRS)

    Unnam, J.; Shenoy, R. N.; Wiedemann, K. E.; Clark, R. K.

    1985-01-01

    A study is conducted of the use of aluminum coatings as oxidation retardants for Ti alloys, using room temperature normal emittance and spectral emittance as bases for the characterization of oxidation properties with and without the coatings. Thermal exposures were conducted in a thermogravimetric analysis apparatus in which specimen weight was continuously monitored. The results obtained indicate that the weight gains are proportional to the square root of the time for uncoated alloys and for 649 C-exposed aluminum-coated alloys. For the 704 C-exposed aluminum-coated alloys, weight gain exhibits a low rate for short and a high rate for long exposure times, implying that the 0.5-micron coating's protection decreases for long exposures at this temperature.

  11. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... drug application, pursuant to section 505 of the Federal Food, Drug, and Cosmetic Act, is in effect for... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73.1015 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

  12. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... drug application, pursuant to section 505 of the Federal Food, Drug, and Cosmetic Act, is in effect for... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73.1015 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

  13. 21 CFR 73.3110a - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide (Pigment Blue 36) (CAS Reg....

  14. 21 CFR 73.3110a - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide (Pigment Blue 36) (CAS Reg....

  15. 21 CFR 73.3110a - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide (Pigment Blue 36) (CAS Reg....

  16. Preparation of titanium dioxide films on etched aluminum foil by vacuum infiltration and anodizing

    NASA Astrophysics Data System (ADS)

    Xiang, Lian; Park, Sang-Shik

    2016-12-01

    Al2O3-TiO2 (Al-Ti) composite oxide films are a promising dielectric material for future use in capacitors. In this study, TiO2 films were prepared on etched Al foils by vacuum infiltration. TiO2 films prepared using a sol-gel process were annealed at various temperatures (450, 500, and 550 °C) for different time durations (10, 30, and 60 min) for 4 cycles, and then anodized at 100 V. The specimens were characterized using X-ray diffraction, field emission scanning electron microscopy, and field emission transmission electron microscopy. The results show that the tunnels of the specimens feature a multi-layer structure consisting of an Al2O3 outer layer, an Al-Ti composite oxide middle layer, and an aluminum hydrate inner layer. The electrical properties of the specimens, such as the withstanding voltage and specific capacitance, were also measured. Compared to specimens without TiO2 coating, the specific capacitances of the TiO2-coated specimens are increased. The specific capacitance of the anode Al foil with TiO2 coating increased by 42% compared to that of a specimen without TiO2 coating when annealed at 550 °C for 10 min. These composite oxide films could enhance the specific capacitance of anode Al foils used in dielectric materials.

  17. Reduction of Oxidative Melt Loss of Aluminum and Its Alloys

    SciTech Connect

    Dr. Subodh K. Das; Shridas Ningileri

    2006-03-17

    This project led to an improved understanding of the mechanisms of dross formation. The microstructural evolution in industrial dross samples was determined. Results suggested that dross that forms in layers with structure and composition determined by the local magnesium concentration alone. This finding is supported by fundamental studies of molten metal surfaces. X-ray photoelectron spectroscopy data revealed that only magnesium segregates to the molten aluminum alloy surface and reacts to form a growing oxide layer. X-ray diffraction techniques that were using to investigate an oxidizing molten aluminum alloy surface confirmed for the first time that magnesium oxide is the initial crystalline phase that forms during metal oxidation. The analytical techniques developed in this project are now available to investigate other molten metal surfaces. Based on the improved understanding of dross initiation, formation and growth, technology was developed to minimize melt loss. The concept is based on covering the molten metal surface with a reusable physical barrier. Tests in a laboratory-scale reverberatory furnace confirmed the results of bench-scale tests. The main highlights of the work done include: A clear understanding of the kinetics of dross formation and the effect of different alloying elements on dross formation was obtained. It was determined that the dross evolves in similar ways regardless of the aluminum alloy being melted and the results showed that amorphous aluminum nitride forms first, followed by amorphous magnesium oxide and crystalline magnesium oxide in all alloys that contain magnesium. Evaluation of the molten aluminum alloy surface during melting and holding indicated that magnesium oxide is the first crystalline phase to form during oxidation of a clean aluminum alloy surface. Based on dross evaluation and melt tests it became clear that the major contributing factor to aluminum alloy dross was in the alloys with Mg content. Mg was

  18. Pure electron-electron dephasing in percolative aluminum ultrathin film grown by molecular beam epitaxy.

    PubMed

    Lin, Shih-Wei; Wu, Yue-Han; Chang, Li; Liang, Chi-Te; Lin, Sheng-Di

    2015-01-01

    We have successfully grown ultrathin continuous aluminum film by molecular beam epitaxy. This percolative aluminum film is single crystalline and strain free as characterized by transmission electron microscopy and atomic force microscopy. The weak anti-localization effect is observed in the temperature range of 1.4 to 10 K with this sample, and it reveals that, for the first time, the dephasing is purely caused by electron-electron inelastic scattering in aluminum.

  19. Micromachined ultrasonic transducers with piezoelectric aluminum nitride thin films

    NASA Astrophysics Data System (ADS)

    Wang, Qianghua

    In this research, a laboratory prototype of micromachined ultrasonic transducer (MUT) has been designed and fabricated with the application of piezoelectric aluminum nitride (AlN) thin films. The fabrication process of MUT device, especially the deposition of AlN thin film, is compatible with a standard integrated circuits (IC) technology. Preliminary results have demonstrated the feasibility of AlN thin film applied in MUT for medical ultrasonic detection. AlN thin film was grown on aluminum metal layer by plasma source molecular beam epitaxy (PSMBE) system. X-ray diffraction (XRD) shows the films exhibit a high c-axis texture for a thickness of 1.2 mum grown at a temperature of 450°C. For the AlN film of 1.20 mum, residual stress was a compressive stress of 883 Mpa, which reduced with increasing thickness of the film. Based on the fundamentals of vibration and piezoelectricity, MUT device including silicon resonator and AlN sandwich structure has been designed. A prototype of 8 x 8 devices on a 3″ silicon (100) wafer has been fabricated. A series of experiments were conducted to find the process flow and the optimum process parameters. MUT devices were characterized by optical, electrical, and acoustic measurements. The measured resonant frequencies AlN MUT and PVDF MUT devices were larger than the calculated value in order of 5% to 12%. The ratios of the flexural frequencies to the fundamental frequency were much close to the MUT design model within a 3% error for AlN MUT devices. Resonant frequencies of AlN MUT devices were also verified by the reflection coefficient with a network analyzer and the electrical impedance with an impendence analyzer. Effective coupling factors of AlN MUT devices were determined to be 0.18 from the resonant frequency and the antiresonant frequency. Fractional bandwidth of an AlN MUT was 8.30% at the center frequency of 2.65 MHz. Pressure sensitivity was stable between 14 mV/MPa and 18 mV/MPa independent on the pressure intensity

  20. Drug release behavior from nanoporous anodic aluminum oxide.

    PubMed

    Kwak, Dae-Hyun; Yoo, Ji-Beom; Kim, Deug Joong

    2010-01-01

    In this study, we developed a new drug delivery system using anodic oxidation. The growth of a porous oxide layer on aluminum under anodic bias in various electrolytes has been studied for more than 40 years. Anodic Aluminum Oxide (AAO) has many uniform nanopores on its surface. This nanoporous surface can be used for drug storage. The effects of the diameter and depth of the AAO on the release characteristics of a drug were investigated. Paclitaxel was used for the drug loading and release test. Paclitaxel was loaded on the inside of the AAO by ultrasonication. The amount of the drug released from the AAO was analyzed by high performance liquid chromatography (HPLC). The pore size did not affect the drug release behavior. However, the depth of the pores had a significant influence on the release rate of the drug.

  1. Exothermic Surface Reactions in Alumina-Aluminum Shell-Core Nanoparticles with Iodine Oxide Decomposition Fragments

    DTIC Science & Technology

    2014-02-22

    AND SUBTITLE Sa. CONTRACT NUMBER Exothennic smface reactions in alumina-aluminum shell-core W911NF-11-1-0439 nanoprui icles with iodine oxide...is observed for aluminum and an iodine -containing oxidizer. This PIR is exothermic and precedes the main exothennic reaction conesponding to aluminum...combustion. For the aluminum and iodine oxide system, exothennic smface chemistiy was recently predicted for I-0 fragments fonning bridge bonds with

  2. Process for fabrication of metal oxide films

    SciTech Connect

    Tracy, C.E.; Benson, D.; Svensson, S.

    1990-07-17

    This invention is comprised of a method of fabricating metal oxide films from a plurality of reactants by inducing a reaction by plasma deposition among the reactants. The plasma reaction is effective for consolidating the reactants and producing thin films of metal oxides, e.g. electro-optically active transition metal oxides, at a high deposition rate. The presence of hydrogen during the plasma reaction enhances the deposition rate of the metal oxide. Various types of metal oxide films can be produced.

  3. Aluminum dross oxide products for the portland cement industry

    SciTech Connect

    Zuck, D.A.

    1995-12-31

    Recovery of aluminum metal from drosses is a major factor in the recyclability success story enjoyed by the United States aluminum industry. Today`s modern dross processor uses the latest technology to maximize metal recovery at the lowest cost while complying with all environmental laws and regulations. Most dross processors, however, pay little attention to the resulting saltcake, the end residual of dross recycling, and rely on landfills for disposition of this material. The alternative is to recycle the saltcake, but the success of this technology is dependent on the development of reliable outlets for each of the saltcake constituents. This paper discusses the evolution of an aluminum dross oxide processing technology that produces an economically attractive source of alumina for the production of portland cement.

  4. Formation of Nanoporous Anodic Alumina by Anodization of Aluminum Films on Glass Substrates.

    PubMed

    Lebyedyeva, Tetyana; Kryvyi, Serhii; Lytvyn, Petro; Skoryk, Mykola; Shpylovyy, Pavlo

    2016-12-01

    Our research was aimed at the study of aluminum films and porous anodic alumina (PAA) films in thin-film РАА/Al structures for optical sensors, based on metal-clad waveguides (MCWG). The results of the scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies of the structure of Al films, deposited by DC magnetron sputtering, and of PAA films, formed on them, are presented in this work.The study showed that the structure of the Al films is defined by the deposition rate of aluminum and the thickness of the film. We saw that under anodization in 0.3 M aqueous oxalic acid solution at a voltage of 40 V, the PAA film with a disordered array of pores was formed on aluminum films 200-600 nm thick, which were deposited on glass substrates with an ultra-thin adhesive Nb layer. The research revealed the formation of two differently sized types of pores. The first type of pores is formed on the grain boundaries of aluminum film, and the pores are directed perpendicularly to the surface of aluminum. The second type of pores is formed directly on the grains of aluminum. They are directed perpendicularly to the grain plains. There is a clear tendency to self-ordering in this type of pores.

  5. An XPS study of the stability of Fomblin Z25 on the native oxide of aluminum. [x ray photoelectron spectroscopy

    NASA Technical Reports Server (NTRS)

    Herrera-Fierro, Pilar; Pepper, Stephen V.; Jones, William R.

    1991-01-01

    Thin films of Fomblin Z25, a perfluoropolyalkylether lubricant, were vapor deposited onto clean, oxidized aluminum and sapphire surfaces, and their behavior at different temperatures was studied using x ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS). It was found that the interfacial fluid molecules decompose on the native oxide at room temperature, and continue to decompose at elevated temperatures, as previous studies had shown to occur on clean metal. TDS indicated that different degradation mechanisms were operative for clean and oxidized aluminum. On sapphire substrates, no reaction was observed at room temperature. Our conclusion is that the native oxide of aluminum is neither passive nor protective towards Fomblin Z25. At high temperatures (150 C) degradation of the polymer on sapphire produced a debris layer at the interface with a chemical composition similar to the one formed on aluminum oxide. Rubbing a Fomblin film on a single crystal sapphire also induced the decomposition of the lubricant in contact with the interface and the formulation of a debris layer.

  6. Shuttle Redesigned Solid Rocket Motor aluminum oxide investigations

    NASA Astrophysics Data System (ADS)

    Blomshield, Fred S.; Kraeutle, Karl J.; Stalnaker, Richard A.

    1994-10-01

    During the launch of STS-54, a 15 psi pressure blip was observed in the ballistic pressure trace of one of the two Space Shuttle Redesigned Solid Rocket Motors (RSRM). One possible scenario for the observed pressure increase deals with aluminum oxide slag formation in the RSRM. The purpose of this investigation was to examine changes which may have occurred in the aluminum oxide formation in shuttle solid propellant due to changes in the ammonium perchlorate. Aluminum oxide formation from three propellants, all having the same formulation, but containing ammonium perchlorate from different manufacturers, will be compared. Three methods have been used to look for possible differences among the propellants. The first method was to examine window bomb movies of the propellants burning at 100, 300 and 600 psia. The motor operating pressure during the pressure blip was around 600 psia. The second method used small samples of propellant which were fired in a combustion bomb which quenched the burning aluminum particles soon after they left the propellant surface. The bomb was fired in both argon and Nitrogen atmospheres at various pressures. Products from this device were examined by optical microscopy. The third method used larger propellant samples fired into a particle collection device which allowed the aluminum to react and combust more completely. This device was pressurized with Nitrogen to motor operating pressures. The collected products were subdivided into size fractions by screening and sedimentation and analyzed optically with an optical microscope. the results from all three methods indicate very small changes in the size distribution of combustion products.

  7. PLASMA POLYMER FILMS AS ADHESION PROMOTING PRIMERS FOR ALUMINUM SUBSTRATES. PART I: CHARACTERIZATION OF FILMS AND FILM/SUBSTRATE INTERFACES

    EPA Science Inventory

    Plasma polymerized hexamethyldisiloxane (HMDSO) films (~800 Å in thickness) were deposited onto aluminum substrates (6111-T4 alloy) in radio frequency (RF) and microwave (MW) powered reactors to be used as primers for structural adhesive bonding. Processing variables such as sub...

  8. Metallic nanoparticle shape and size effects on aluminum oxide-induced enhancement of exciton-plasmon coupling and quantum dot emission

    SciTech Connect

    Wing, Waylin J.; Sadeghi, Seyed M. Gutha, Rithvik R.; Campbell, Quinn; Mao, Chuanbin

    2015-09-28

    We investigate the shape and size effects of gold metallic nanoparticles on the enhancement of exciton-plasmon coupling and emission of semiconductor quantum dots induced via the simultaneous impact of metal-oxide and plasmonic effects. This enhancement occurs when metallic nanoparticle arrays are separated from the quantum dots by a layered thin film consisting of a high index dielectric material (silicon) and aluminum oxide. Our results show that adding the aluminum oxide layer can increase the degree of polarization of quantum dot emission induced by metallic nanorods by nearly two times, when these nanorods have large aspect ratios. We show when the aspect ratio of these nanorods is reduced to half, the aluminum oxide loses its impact, leading to no improvement in the degree of polarization. These results suggest that a silicon/aluminum oxide layer can significantly enhance exciton-plasmon coupling when quantum dots are in the vicinity of metallic nanoantennas with high aspect ratios.

  9. Metallic nanoparticle shape and size effects on aluminum oxide-induced enhancement of exciton-plasmon coupling and quantum dot emission.

    PubMed

    Wing, Waylin J; Sadeghi, Seyed M; Gutha, Rithvik R; Campbell, Quinn; Mao, Chuanbin

    2015-09-28

    We investigate the shape and size effects of gold metallic nanoparticles on the enhancement of exciton-plasmon coupling and emission of semiconductor quantum dots induced via the simultaneous impact of metal-oxide and plasmonic effects. This enhancement occurs when metallic nanoparticle arrays are separated from the quantum dots by a layered thin film consisting of a high index dielectric material (silicon) and aluminum oxide. Our results show that adding the aluminum oxide layer can increase the degree of polarization of quantum dot emission induced by metallic nanorods by nearly two times, when these nanorods have large aspect ratios. We show when the aspect ratio of these nanorods is reduced to half, the aluminum oxide loses its impact, leading to no improvement in the degree of polarization. These results suggest that a silicon/aluminum oxide layer can significantly enhance exciton-plasmon coupling when quantum dots are in the vicinity of metallic nanoantennas with high aspect ratios.

  10. Aluminum recycling from reactor walls: A source of contamination in a-Si:H thin films

    SciTech Connect

    Longeaud, C.; Ray, P. P.; Bhaduri, A.; Daineka, D.; Johnson, E. V.; Roca i Cabarrocas, P.

    2010-11-15

    In this article, the authors investigate the contamination of hydrogenated amorphous silicon thin films with aluminum recycled from the walls and electrodes of the deposition reactor. Thin films of hydrogenated amorphous silicon were prepared under various conditions by a standard radio frequency plasma enhanced chemical vapor deposition process in two reactors, the chambers of which were constructed of either aluminum or stainless steel. The authors have studied the electronic properties of these thin films and have found that when using an aluminum reactor chamber, the layers are contaminated with aluminum recycled from the chamber walls and electrode. This phenomenon is observed almost independently of the deposition conditions. The authors show that this contamination results in slightly p-doped films and could be detrimental to the deposition of device grade films. The authors also propose a simple way to control and eventually suppress this contamination.

  11. Formation of Nanoporous Anodic Alumina by Anodization of Aluminum Films on Glass Substrates

    NASA Astrophysics Data System (ADS)

    Lebyedyeva, Tetyana; Kryvyi, Serhii; Lytvyn, Petro; Skoryk, Mykola; Shpylovyy, Pavlo

    2016-04-01

    Our research was aimed at the study of aluminum films and porous anodic alumina (PAA) films in thin-film PAA/Al structures for optical sensors, based on metal-clad waveguides (MCWG). The results of the scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies of the structure of Al films, deposited by DC magnetron sputtering, and of PAA films, formed on them, are presented in this work.

  12. Characteristic Exoemission From Oxide Covered Aluminum Alloys.

    DTIC Science & Technology

    1978-07-01

    sharp end mill . Sn all cuts wcr’ taken to present exeessise defornia. ~don. Aft~t riachining, the edges of she tensile specim ens were —carefully de...end Himmel 5268 - 1 in addition, the peak position is a function of oxide thickness (Fig. 12). Above 500 A , the peak position A FSOM A~ NOTT AND SAM...traditional dogbone shape from 20 mil (0.013 cm) thick production stock. A slow milling process was used to avoid unnecessary stresses and temperature

  13. Tailoring oxidation of aluminum nanoparticles reinforced with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sharma, Manjula; Sharma, Vimal

    2016-05-01

    In this report, the oxidation temperature and reaction enthalpy of Aluminum (Al) nanoparticles has been controlled by reinforcing with carbon nanotubes. The physical mixing method with ultrasonication was employed to synthesize CNT/Al nanocomposite powders. The micro-morphology of nanoconmposite powders has been analysed by scanning electron microscopy, energy dispersive spectroscopy, raman spectroscopy and X-ray diffraction techniques. The oxidation behavior of nanocomposite powders analyzed by thermogravimetry/differential scanning calorimertry showed improvement in the exothermic enthalpy. Largest exothermic enthalpy of-1251J/g was observed for CNT (4 wt%)/Al nanocomposite.

  14. A preliminary study of ester oxidation on an aluminum surface using chemiluminescence

    NASA Technical Reports Server (NTRS)

    Jones, William R., Jr.; Meador, Michael A.; Morales, Wilfredo

    1987-01-01

    The oxidation characteristics of a pure ester (trimethyolpropane triheptanoate) were studied by using a chemiluminescence technique. Tests were run in a thin-film micro-oxidation apparatus with an aluminum alloy catalyst. Conditions included a pure oxygen atmosphere and a temperature range of 176 to 206 C. Results indicated that oxidation of the ester (containing 10 to the minus 3rd power M diphenylanthracene as an intensifier) was accompanied by emission of light. The maximum intensity of light emission (I sub max) was a function of the amount of ester, the concentration of intensifier, and the test temperature. The induction period or the time to reach one-half of maximum intensity (t sub 1/2) was an inverse function of test temperature. Decreases in light emission at the later stages of a test were caused by depletion of the intensifier.

  15. A preliminary study of ester oxidation on an aluminum surface using chemiluminescence

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Meador, M. A.; Morales, W.

    1986-01-01

    The oxidation characteristics of a pure ester (trimethyolpropane triheptanoate) were studied by using a chemiluminescence technique. Tests were run in a thin-film micro-oxidation apparatus with an aluminum alloy catalyst. Conditions included a pure oxygen atmosphere and a temperature range of 176 to 206 C. Results indicated that oxidation of the ester (containing 10 to the minus 3 power M diphenylanthracene as an intensifier) was accompanied by emission of light. The maximum intensity of light emission (I sub max) was a function of the amount of ester, the concentration of intensifier, and the test temperature. The induction period or the time to reach one-half of maximum intensity (t sub 1/2) was an inverse function of test temperature. Decreases in light emission at the later stages of a test were caused by depletion of the intensifier.

  16. A nine-atom rhodium–aluminum oxide cluster oxidizes five carbon monoxide molecules

    PubMed Central

    Li, Xiao-Na; Zhang, Hua-Min; Yuan, Zhen; He, Sheng-Gui

    2016-01-01

    Noble metals can promote the direct participation of lattice oxygen of very stable oxide materials such as aluminum oxide, to oxidize reactant molecules, while the fundamental mechanism of noble metal catalysis is elusive. Here we report that a single atom of rhodium, a powerful noble metal catalyst, can promote the transfer of five oxygen atoms to oxidize carbon monoxide from a nine-atom rhodium–aluminum oxide cluster. This is a sharp improvement in the field of cluster science where the transfer of at most two oxygen atoms from a doped cluster is more commonly observed. Rhodium functions not only as the preferred trapping site to anchor and oxidize carbon monoxide by the oxygen atoms in direct connection with rhodium but also the primarily oxidative centre to accumulate the large amounts of electrons and the polarity of rhodium is ultimately transformed from positive to negative. PMID:27094921

  17. The effect of magnesium oxide supplementation to aluminum oxide slip on the jointing of aluminum oxide bars.

    PubMed

    Odatsu, Tetsurou; Sawase, Takashi; Kamada, Kohji; Taira, Yohsuke; Shiraishi, Takanobu; Atsuta, Mitsuru

    2008-03-01

    The purpose of this study was to investigate the effect of modifying aluminum oxide slips with magnesium oxide (MgO) to create a jointing material for In-Ceram Alumina. Jointed In-Ceram Alumina bars with In-Ceram Alumina slips containing 0-1.0 mass% MgO were examined by a three-point bending test. Joint-free bars were also tested as controls. Fracture surfaces were evaluated by scanning electron microscopy. In addition, linear shrinkage and fracture toughness were assessed. The 0.3 mass% MgO group showed the highest flexural strength among the jointed groups, and there were no statistical differences between the joint-free control groups. The fracture surface of 0.3 mass% MgO group showed increased sintering densification with reduced micropore size. No linear shrinkage was observed with the addition of MgO to the alumina slip. Added MgO was also effective in boosting fracture toughness. The present findings indicate that the MgO-supplemented binding material is useful for clinical applications.

  18. The role of stress in self-ordered porous anodic oxide formation and corrosion of aluminum

    NASA Astrophysics Data System (ADS)

    Capraz, Omer Ozgur

    The phenomenon of plastic flow induced by electrochemical reactions near room temperature is significant in porous anodic oxide (PAO) films, charging of lithium batteries and stress-corrosion cracking (SCC). As this phenomenon is poorly understood, fundamental insight into flow from our work may provide useful information for these problems. In-situ monitoring of the stress state allows direct correlation between stress and the current or potential, thus providing fundamental insight into technologically important deformation and failure mechanisms induced by electrochemical reactions. A phase-shifting curvature interferometry was designed to investigate the stress generation mechanisms on different systems. Resolution of our curvature interferometry was found to be ten times more powerful than that obtained by state-of-art multiple deflectometry technique and the curvature interferometry helps to resolve the conflicting reports in the literature. During this work, formation of surface patterns during both aqueous corrosion of aluminum and formation of PAO films were investigated. Interestingly, for both cases, stress induced plastic flow controls the formation of surface patterns. Pore formation mechanisms during anodizing of the porous aluminum oxide films was investigated . PAO films are formed by the electrochemical oxidation of metals such as aluminum and titanium in a solution where oxide is moderately soluble. They have been used extensively to design numerous devices for optical, catalytic, and biological and energy related applications, due to their vertically aligned-geometry, high-specific surface area and tunable geometry by adjusting process variables. These structures have developed empirically, in the absence of understanding the process mechanism. Previous experimental studies of anodizing-induced stress have extensively focused on the measurement of average stress, however the measurement of stress evolution during anodizing does not provide

  19. Nanopore gradients on porous aluminum oxide generated by nonuniform anodization of aluminum.

    PubMed

    Kant, Krishna; Low, Suet P; Marshal, Asif; Shapter, Joseph G; Losic, Dusan

    2010-12-01

    A method for surface engineering of structural gradients with nanopore topography using the self-ordering process based on electrochemical anodization of aluminum is described. A distinct anodization condition with an asymmetrically distributed electric field at the electrolyte/aluminum interface is created by nonparallel arrangement between electrodes (tilted by 45°) in an electrochemical cell. The anodic aluminum oxide (AAO) porous surfaces with ordered nanopore structures with gradual and continuous change of pore diameters from 80 to 300 nm across an area of 0.5-1 cm were fabricated by this anodization using two common electrolytes, oxalic acid (0.3 M) and phosphoric acid (0.3 M). The formation of pore gradients of AAO is explained by asymmetric and gradual distribution of the current density and temperature variation generated on the surface of Al during the anodization process. Optical and wetting gradients of prepared pore structures were confirmed by reflective interferometric spectroscopy and contact angle measurements showing the ability of this method to generate porous surfaces with multifunctional gradients (structural, optical, wetting). The study of influence of pore structures on cell growth using the culture of neuroblastoma cells reveals biological relevance of nanopore gradients and the potential to be applied as the platform for spatially controllable cell growth and cell differentiation.

  20. Pulsed laser deposition: A viable route for the growth of aluminum antimonide film

    NASA Astrophysics Data System (ADS)

    Das, S.; Ghosh, B.; Hussain, S.; Bhar, R.; Pal, A. K.

    2015-06-01

    Aluminum antimonide films (AlSb) were successfully deposited on glass substrates by ablating an aluminum antimonide target using pulsed Nd-YAG laser. Films deposited at substrate temperatures 773 K and above showed zinc blende structure. Increase in substrate temperature culminated in grain growth in the films. Photoluminescence studies indicated a strong peak 725 nm ( 1.71 eV) and 803 nm ( 1.55 eV). Films deposited at higher deposition temperatures indicated lower residual strain. Characteristic Raman peaks for AlSb at 151 cm-1 followed by two peaks located at 71 cm-1 and 116 cm-1 were also observed.

  1. Growth, interfacial alloying, and oxidation of ultra-thin Al films on Ru(0001)

    NASA Astrophysics Data System (ADS)

    Wu, Yutong; Tao, Hui-Shu; Garfunkel, Eric; Madey, Theodore E.; Shinn, Neal D.

    1995-08-01

    The growth and oxidation of ultra-thin aluminum films on Ru(0001) have been studied by low energy ion scattering (LEIS) and X-ray photoelectron spectroscopy (XPS) using both Mg K α and synchrotron soft X-ray radiation. For Al films of average thickness ˜ 15 Å deposited at 300 K, LEIS demonstrates that the Ru substrate is completely covered. Upon annealing to ˜ 1000 K LEIS shows the reappearance of Ru at the surface. At the same time, the metallic Al 2p peak shifts to lower binding energy and a low binding energy shoulder appears on the Ru 3d peak, suggesting {Al}/{Ru} interfacial alloying. Annealing Al films to ˜ 1000 K in 1 × 10 -4 Torr oxygen produces an oxidized surface layer that completely covers the Ru substrate; the resultant aluminum oxide films are stoichiometric.

  2. Screen Cage Ion Plating (SCIP) and scratch testing of polycrystalline aluminum oxide

    NASA Technical Reports Server (NTRS)

    Spalvins, Talivaldis; Sliney, Harold E.; Deadmore, Daniel L.

    1992-01-01

    A screen cage ion plating (SCIP) technique was developed to apply silver films on electrically nonconducting aluminum oxide. It is shown that SCIP has remarkable throwing power; surfaces to be coated need not be in direct line of sight with the evaporation source. Scratch tests, employing a diamond stylus with a 200 micro m radius tip, were performed on uncoated and on silver coated alumina. Subsequent surface analysis show that a significant amount of silver remains on the scratched surfaces, even in areas where high stylus load produced severe crack patterns in the ceramic. Friction coefficients were lowered during the scratch tests on the coated alumina indicating that this modification of the ion planting process should be useful for applying lubricating films of soft metals to electrical insulating materials. The very good throwing power of SCIP also strongly suggests general applicability of this process in other areas of technology, e.g., electronics, in addition to tribology.

  3. Fabrication of Fe-Al nanoparticles by selective oxidation of Fe-Al thin films

    NASA Astrophysics Data System (ADS)

    Jang, Pyungwoo; Shin, Seungchan; Jung, Chip-Sup; Kim, Kwang-Ho; Seomoon, Kyu

    2013-04-01

    The possibility of a new technique for fabricating nanoparticles from thin films using selective oxidation in an atmosphere mixture of water vapor and hydrogen was investigated. Fe-5wt.%Al films were RF-sputtered and annealed in the atmosphere mixture at 900°C for up to 200 min, in order to oxidize aluminum selectively. Thermodynamics simulation showed that temperatures exceeding 800°C are necessary to prevent iron from being oxidized, as confirmed by the depth profile of XPS. As the annealing time increased, the morphology of the 200-nm Fe-Al films changed from the continuous to the discontinuous type; thus, particulate Fe-Al films formed after 100 min. The particulate 10- to 100-nm Fe-Al films showed super-paramagnetic behavior after the oxidation. Thus, a new technique for fabricating nanoparticles was successfully introduced using selective oxidation.

  4. Aqueous process to limit hydration of thin-film inorganic oxides

    NASA Astrophysics Data System (ADS)

    Perkins, Cory K.; Mansergh, Ryan H.; Park, Deok-Hie; Nanayakkara, Charith E.; Ramos, Juan C.; Decker, Shawn R.; Huang, Yu; Chabal, Yves J.; Keszler, Douglas A.

    2016-11-01

    Aqueous-processed aluminum oxide phosphate (AlPO) dielectric films were studied to determine how water desorbs and absorbs on heating and cooling, respectively. In-situ Fourier transform infrared spectroscopy showed a distinct, reversible mono- to bidentate phosphate structural change associated with water loss and uptake. Temperature programmed desorption measurements on a 1-μm thick AlPO film revealed water sorption was inhibited by an aqueous-processed HfO2 capping film only 11-nm thick. The HfO2 capping film prevents water resorption, thereby preserving the exceptional performance of AlPO as a thin-film dielectric.

  5. Aircraft water vapor measurements utilizing an aluminum oxide hygrometer

    NASA Technical Reports Server (NTRS)

    Hilsenrath, E.

    1973-01-01

    A hygrometer for water vapor measurements from an aircraft has been developed. An aluminum oxide hygrometer mounted in an aircraft Rosemount air temperature scoop was flown on NASA and USAF aircraft. Water vapor measurements were conducted up to 40,000 feet with penetration into the stratosphere. Good agreement was obtained with simultaneously flown remote sounders of water vapor. During transcontinental flights the hygrometer demonstrated adequate response to measure the natural variability of water vapor near the tropopause. Rapid response was demonstrated in pursuit of the jet wake of an F-104 at 35,000 feet.

  6. Aircraft water vapor measurements utilizing an aluminum oxide hygrometer

    NASA Technical Reports Server (NTRS)

    Hilsenrath, E.

    1974-01-01

    A hygrometer for water vapor measurements from an aircraft was developed. An aluminum oxide hygrometer mounted in an aircraft Rosemount air temperature scoop was flown on the NASA Convair 990 and on a USAF B-57 aircraft. Water vapor measurements from the Convair 990 were conducted up to 40,000 ft with penetration into the stratosphere. Good agreement was obtained with simultaneously flown remote sounders of water vapor. During transcontinental flights the hygrometer demonstrated adequate response to measure the natural variability of water vapor near the tropopause. Rapid response was demonstrated in pursuit of the jet wake of an F-104 at 35,000 ft.

  7. Chemical dynamics of nano-aluminum/iodine (V) oxide

    NASA Astrophysics Data System (ADS)

    Little, B. K.; Welle, E. J.; Emery, S. B.; Bogle, M. B.; Ashley, V. L.; Schrand, A. M.; Lindsay, C. M.

    2014-05-01

    This proceeding describes our preliminary efforts in studying highly reactive composites containing crystalline iodine (V) oxide and nano-aluminum (nAl) with various amounts of cyclohexanone in the form of powders. In this study we report upon the application of physiochemical techniques such as thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), powdered X-ray diffraction (PXRD), and electron microscopy for chemical characterization of powder composites. In addition dynamic measurements were conducted by recording pressure trace profiles during a combustion event. These various techniques were employed to examine these energetic materials (EMs) and associate changes to the chemical dynamics of the composite with the additive.

  8. Light extraction enhancement of organic light-emitting diodes using aluminum zinc oxide embedded anodes.

    PubMed

    Hsu, Ching-Ming; Lin, Bo-Ting; Zeng, Yin-Xing; Lin, Wei-Ming; Wu, Wen-Tuan

    2014-12-15

    Aluminum zinc oxide (AZO) has been embedded onto indium tin oxide (ITO) anode to enhance the light extraction from an organic light-emitting diode (OLED). The embedded AZO provides deflection and scattering interfaces on the newly generated AZO/organics and AZO/ITO interfaces rather than the conventional ITO/organic interface. The current efficiency of AZO embedded OLEDs was enhanced by up to 64%, attributed to the improved light extraction by additionally created reflection and scattering of emitted light on the AZO/ITO interfaces which was roughed in AZO embedding process. The current efficiency was found to increase with the increasing AZO embedded area ratio, but limited by the accompanying increases in haze and electrical resistance of the AZO embedded ITO film.

  9. Thin film hydrous metal oxide catalysts

    DOEpatents

    Dosch, Robert G.; Stephens, Howard P.

    1995-01-01

    Thin film (<100 nm) hydrous metal oxide catalysts are prepared by 1) synthesis of a hydrous metal oxide, 2) deposition of the hydrous metal oxide upon an inert support surface, 3) ion exchange with catalytically active metals, and 4) activating the hydrous metal oxide catalysts.

  10. Simultaneous deposition of diamondlike carbon films on both surfaces of aluminum substrate by electrochemical technique

    NASA Astrophysics Data System (ADS)

    Li, R. S.; Zhou, M.; Pan, X. J.; Zhang, Z. X.; Lu, B. A.; Wang, T.; Xie, E. Q.

    2009-03-01

    By electrolysis of the N ,N-dimethylformamide solution, an attempt was made to simultaneously deposit diamondlike carbon (DLC) films on both surfaces of an aluminum (Al) substrate. Raman spectra showed that the structures of the DLC film were uniform. The thickness distribution of the film was 260-300 nm. A simple model of the sustaining mechanism was proposed for simultaneous electrodeposition of the DLC film on both surfaces of conductive substrates. The simultaneous formation of the DLC film on both surfaces of the Al substrate showed a possibility in the three-dimensional deposition of DLC films on complex conductive substrates.

  11. Island growth in the atomic layer deposition of zirconium oxide and aluminum oxide on hydrogen-terminated silicon: Growth mode modeling and transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Puurunen, Riikka L.; Vandervorst, Wilfried; Besling, Wim F. A.; Richard, Olivier; Bender, Hugo; Conard, Thierry; Zhao, Chao; Delabie, Annelies; Caymax, Matty; De Gendt, Stefan; Heyns, Marc; Viitanen, Minna M.; de Ridder, Marco; Brongersma, Hidde H.; Tamminga, Yde; Dao, Thuy; de Win, Toon; Verheijen, Marcel; Kaiser, Monja; Tuominen, Marko

    2004-11-01

    Atomic layer deposition (ALD) is used in applications where inorganic material layers with uniform thickness down to the nanometer range are required. For such thicknesses, the growth mode, defining how the material is arranged on the surface during the growth, is of critical importance. In this work, the growth mode of the zirconium tetrachloride/water and the trimethyl aluminum/water ALD process on hydrogen-terminated silicon was investigated by combining information on the total amount of material deposited with information on the surface fraction of the material. The total amount of material deposited was measured by Rutherford backscattering, x-ray fluorescence, and inductively coupled plasma-optical emission spectroscopy, and the surface fractions by low-energy ion scattering. Growth mode modeling was made assuming two-dimensional growth or random deposition (RD), with a "shower model" of RD recently developed for ALD. Experimental surface fractions of the ALD-grown zirconium oxide and aluminum oxide films were lower than the surface fractions calculated assuming RD, suggesting the occurrence of island growth. Island growth was confirmed with transmission electron microscopy (TEM) measurements, from which the island size and number of islands per unit surface area could also be estimated. The conclusion of island growth for the aluminum oxide deposition on hydrogen-terminated silicon contradicts earlier observations. In this work, physical aluminum oxide islands were observed in TEM after 15 ALD reaction cycles. Earlier, thicker aluminum oxide layers have been analyzed, where islands have not been observed because they have already coalesced to form a continuous film. The unreactivity of hydrogen-terminated silicon surface towards the ALD reactants, except for reactive defect areas, is proposed as the origin of island growth. Consequently, island growth can be regarded as "undesired surface-selective ALD."

  12. Impact of annealing temperature on the mechanical and electrical properties of sputtered aluminum nitride thin films

    SciTech Connect

    Gillinger, M.; Schneider, M.; Bittner, A.; Schmid, U.; Nicolay, P.

    2015-02-14

    Aluminium nitride (AlN) is a promising material for challenging sensor applications such as process monitoring in harsh environments (e.g., turbine exhaust), due to its piezoelectric properties, its high temperature stability and good thermal match to silicon. Basically, the operational temperature of piezoelectric materials is limited by the increase of the leakage current as well as by enhanced diffusion effects in the material at elevated temperatures. This work focuses on the characterization of aluminum nitride thin films after post deposition annealings up to temperatures of 1000 °C in harsh environments. For this purpose, thin film samples were temperature loaded for 2 h in pure nitrogen and oxygen gas atmospheres and characterized with respect to the film stress and the leakage current behaviour. The X-ray diffraction results show that AlN thin films are chemically stable in oxygen atmospheres for 2 h at annealing temperatures of up to 900 °C. At 1000 °C, a 100 nm thick AlN layer oxidizes completely. For nitrogen, the layer is stable up to 1000 °C. The activation energy of the samples was determined from leakage current measurements at different sample temperatures, in the range between 25 and 300 °C. Up to an annealing temperature of 700 °C, the leakage current in the thin film is dominated by Poole-Frenkel behavior, while at higher annealing temperatures, a mixture of different leakage current mechanisms is observed.

  13. Large-scale ordering of porous Si using anodic aluminum oxide grown by directed self-assembly

    SciTech Connect

    Zou Jia; Qi Xiaoyuan; Tan Liwen; Stadler, Bethanie J. H.

    2006-08-28

    Porous Si with perfect long range order (mm{sup 2} scale) was obtained using an integrated mask of ordered anodic aluminum oxide (AAO). This represents an increase of many orders of magnitude in the ordered domain size compared with porous Si made with self-assembled AAO masks. Here, master stamps composed of silicon nitride posts (180 nm diameter, 400 nm spacing) were imprinted into Al films that were grown onto nitride-coated Si wafers. The Al films were then anodized and the resulting ordered, nanoporous pattern was transferred into the Si using reactive ion etching. The stamps could be reused a multitude of times to produce exact replicas.

  14. Large-scale ordering of porous Si using anodic aluminum oxide grown by directed self-assembly

    NASA Astrophysics Data System (ADS)

    Zou, Jia; Qi, Xiaoyuan; Tan, Liwen; Stadler, Bethanie J. H.

    2006-08-01

    Porous Si with perfect long range order (mm2 scale) was obtained using an integrated mask of ordered anodic aluminum oxide (AAO). This represents an increase of many orders of magnitude in the ordered domain size compared with porous Si made with self-assembled AAO masks. Here, master stamps composed of silicon nitride posts (180nm diameter, 400nm spacing) were imprinted into Al films that were grown onto nitride-coated Si wafers. The Al films were then anodized and the resulting ordered, nanoporous pattern was transferred into the Si using reactive ion etching. The stamps could be reused a multitude of times to produce exact replicas.

  15. Uranyl and Arsenate Cosorption on Aluminum Oxide Surface

    SciTech Connect

    Tang, Y.; Reeder, R

    2009-01-01

    In this study, we examined the effects of simultaneous adsorption of aqueous arsenate and uranyl onto aluminum oxide over a range of pH and concentration conditions. Arsenate was used as a chemical analog for phosphate, and offers advantages for characterization via X-ray absorption spectroscopy. By combining batch experiments, speciation calculations, X-ray absorption spectroscopy, and X-ray diffraction, we investigated the uptake behavior of uranyl, as well as the local and long-range structure of the final sorption products. In the presence of arsenate, uranyl sorption was greatly enhanced in the acidic pH range, and the amount of enhancement is positively correlated to the initial arsenate and uranyl concentrations. At pH 4-6, U L{sub III-} and As K-edge EXAFS results suggest the formation of surface-sorbed uranyl and arsenate species as well as uranyl arsenate surface precipitate(s) that have a structure similar to tr{umlt o}gerite. Uranyl polymeric species or oxyhydroxide precipitate(s) become more important with increasing pH values. Our results provide the basis for predictive models of the uptake of uranyl by aluminum oxide in the presence of arsenate and (by analogy) phosphate, which can be especially important for understanding phosphate-based uranium remediation systems.

  16. Interfacial charging phenomena of aluminum (hydr)oxides

    SciTech Connect

    Hiemstra, T.; Yong, H.; Van Riemsdijk, W.H.

    1999-08-31

    The interfacial charging of Al(OH){sub 3} (gibbsite and bayerite) and Al{sub 2}O{sub 3} has been studied. For Al(OH){sub 3} it can be shown that the very strong variation in charging behavior for different preparations is related to the relative presence of differently reacting crystal planes. The edge faces of the hexagonal gibbsite crystals are proton reactive over the whole pH range, in contrast to the 001 plane, which is mainly uncharged below pH = 10. On this 001 face only doubly coordinated surface groups are found, in contrast to the edges which also have singly coordinated surface groups. The results are fully in agreement with the predictions of the Multi site complexation (MUSIC) model. The proton adsorption, electrolyte ion adsorption, and shift of the IEP of gibbsite and aluminum oxide have been modeled simultaneously. For gibbsite, the ion pair formation of Na is larger than that of Cl, as is evidenced by modeling the experimentally observed upward shift on the IEP and charge reversal at high electrolyte concentrations. All these experimental results can be satisfactorily modeled with the MUSIC model, including the experimental surface potential of aluminum oxide (ISFET).

  17. Adsorption and transformation of tetracycline antibiotics with aluminum oxide.

    PubMed

    Chen, Wan-Ru; Huang, Ching-Hua

    2010-05-01

    Tetracycline antibiotics (TCs) including tetracycline (TTC), chlorotetracycline (CTC) and oxytetracycline (OTC) adsorb strongly to aluminum oxide (Al(2)O(3)), and the surface interaction promotes structural transformation of TCs. The latter phenomenon was not widely recognized previously. Typically, rapid adsorption of TCs to Al(2)O(3) occurs in the first 3h ([TC]=40microM, [Al(2)O(3)]=1.78gL(-1), pH=5, and T=22 degrees C), followed by continuous first-order decay of the parent compound (k(obs)=15+/-1.0, 18+/-1.0 and 6.2+/-0.9x10(-3)h(-1) for TTC, CTC and OTC, respectively) and product formation. The transformation reaction rate of TCs strongly correlates with adsorption to Al(2)O(3) surfaces. Both adsorption and transformation occur at the highest rate at around neutral pH conditions. Product evaluation indicates that Al(2)O(3) promotes dehydration of TTC to yield anhydrotetracycline (AHTTC), epimerization of TTC, and formation of Al-TTC complexes. Al(2)O(3) promotes predominantly the transformation of CTC to iso-CTC. The surface-bound Al(+III) acts as a Lewis acid site to promote the above transformation of TCs. Formation of AHTTC is of special concern because of its higher cytotoxicity. Results of this study indicate that aluminum oxide will likely affect the fate of TC antibiotics in the aquatic environment via both adsorption and transformation.

  18. Comparative effects of macro-sized aluminum oxide and aluminum oxide nanoparticles on erythrocyte hemolysis: influence of cell source, temperature, and size

    NASA Astrophysics Data System (ADS)

    Vinardell, M. P.; Sordé, A.; Díaz, J.; Baccarin, T.; Mitjans, M.

    2015-02-01

    Al2O3 is the most abundantly produced nanomaterial and has been used in diverse fields, including the medical, military, and industrial sectors. As there are concerns about the health effects of nanoparticles, it is important to understand how they interact with cells, and specifically with red blood cells. The hemolysis induced by three commercial nano-sized aluminum oxide particles (nanopowder 13 nm, nanopowder <50 nm, and nanowire 2-6 × 200-400 nm) was compared to aluminum oxide and has been studied on erythrocytes from humans, rats, and rabbits, in order to elucidate the mechanism of action and the influence of size and shape on hemolytic behavior. The concentrations inducing 50 % hemolysis (HC50) were calculated for each compound studied. The most hemolytic aluminum oxide particles were of nanopowder 13, followed by nanowire and nanopowder 50. The addition of albumin to PBS induced a protective effect on hemolysis in all the nano-forms of Al2O3, but not on Al2O3. The drop in HC50 correlated to a decrease in nanomaterial size, which was induced by a reduction of aggregation. Aluminum oxide nanoparticles are less hemolytic than other oxide nanoparticles and behave differently depending on the size and shape of the nanoparticles. The hemolytic behavior of aluminum oxide nanoparticles differs from that of aluminum oxide.

  19. Wettability of biomimetic thermally grown aluminum oxide coatings.

    PubMed

    Samad, Jadid E; Nychka, John A

    2011-03-01

    In this paper, wettability behavior of a rough but intrinsically hydrophilic oxide ceramic, formed via simple thermal oxidation of a commercial metallic alloy in laboratory air, has been analyzed. Drop shape analysis (DSA) revealed static water contact angles for the rough ceramic surfaces up to 128° (greater than for Teflon™). We propose the high apparent contact angles to be a result of surface roughening via the morphological changes of the oxide scale with oxidation conditions. The surface morphological changes occurring during the growth of the oxide film resulted in the formation of vertical platelets that ably shifted the wetting behavior from a Wenzel to an unstable Cassie-Baxter state. The platelet morphology of the ceramic resembles the structure of epicuticular waxes on certain species of superhydrophobic leaves. Moreover, surface textures for very short oxidation times were also found to increase hydrophilicity in the scale and reduce the contact angle by imparting a Wenzel state. Various characterization techniques (XRD, XPS, and SEM) were performed in order to detect the crystallographic phases in the scales, analyze carbon content and determine the morphology of the oxide layer. Morphological features of the oxide platelets were quantified and platelet width, spacing and height were found to correlate well with the apparent contact angle trend as a function of oxidation time.

  20. Corrosion evaluation of zirconium doped oxide coatings on aluminum formed by plasma electrolytic oxidation.

    PubMed

    Bajat, Jelena; Mišković-Stanković, Vesna; Vasilić, Rastko; Stojadinović, Stevan

    2014-01-01

    The plasma electrolytic oxidation (PEO) of aluminum in sodium tungstate (Na(2)WO(4) · (2)H(2)O) and Na(2)WO(4) · (2)H(2)O doped with Zr was analyzed in order to obtain oxide coatings with improved corrosion resistance. The influence of current density in PEO process and anodization time was investigated, as well as the influence of Zr, with the aim to find out how they affect the chemical content, morphology, surface roughness, and corrosion stability of oxide coatings. It was shown that the presence of Zr increases the corrosion stability of oxide coatings for all investigated PEO times. Evolution of EIS spectra during the exposure to 3% NaCl, as a strong corrosive agent, indicated the highest corrosion stability for PEO coating formed on aluminum at 70 mA/cm(2) for 2 min in a zirconium containing electrolyte.

  1. Effect of grain size on the melting point of confined thin aluminum films

    SciTech Connect

    Wejrzanowski, Tomasz; Lewandowska, Malgorzata; Sikorski, Krzysztof; Kurzydlowski, Krzysztof J.

    2014-10-28

    The melting of aluminum thin film was studied by a molecular dynamics (MD) simulation technique. The effect of the grain size and type of confinement was investigated for aluminum film with a constant thickness of 4 nm. The results show that coherent intercrystalline interface suppress the transition of solid aluminum into liquid, while free-surface gives melting point depression. The mechanism of melting of polycrystalline aluminum thin film was investigated. It was found that melting starts at grain boundaries and propagates to grain interiors. The melting point was calculated from the Lindemann index criterion, taking into account only atoms near to grain boundaries. This made it possible to extend melting point calculations to bigger grains, which require a long time (in the MD scale) to be fully molten. The results show that 4 nm thick film of aluminum melts at a temperature lower than the melting point of bulk aluminum (933 K) only when the grain size is reduced to 6 nm.

  2. The effect of plasma electrolytic oxidation on the mean stress sensitivity of the fatigue life of the 6082 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Winter, L.; Morgenstern, R.; Hockauf, K.; Lampke, T.

    2016-03-01

    In this work the mean stress influence on the high cycle fatigue behavior of the plasma electrolytic oxidized (PEO) 6082 aluminum alloy (AlSi1MgMn) is investigated. The present study is focused on the fatigue life time and the susceptibility of fatigue-induced cracking of the oxide coating and their dependence on the applied mean stress. Systematic work is done comparing conditions with and without PEO treatment, which have been tested using three different load ratios. For the uncoated substrate the cycles to failure show a significant dependence on the mean stress, which is typical for aluminum alloys. With increased load ratio and therefore increased mean stress, the fatigue strength decreases. The investigation confirms the well-known effect of PEO treatment on the fatigue life: The fatigue strength is significantly reduced by the PEO process, compared to the uncoated substrate. However, also the mean stress sensitivity of the fatigue performance is reduced. The fatigue limit is not influenced by an increasing mean stress for the PEO treated conditions. This effect is firstly shown in these findings and no explanation for this effect can be found in literature. Supposedly the internal compressive stresses and the micro-cracks in the oxide film have a direct influence on the crack initiation and growth from the oxide film through the interface and in the substrate. Contrary to these findings, the susceptibility of fatigue-induced cracking of the oxide coating is influenced by the load ratio. At tension-tension loading a large number of cracks, which grow partially just in the aluminum substrate, are present. With decreasing load ratio to alternating tension-compression stresses, the crack number and length increases and shattering of the oxide film is more pronounced due to the additional effective compressive part of the load cycle.

  3. Experimental study to validate a model of hillock{close_quote}s formation in aluminum thin films

    SciTech Connect

    Genin, F.Y.; Siekhaus, W.J.

    1996-04-01

    The growth of holes and hillocks in thin films has been reported extensively and for a multitude of film{endash}substrate systems. A recently developed model [F. Y. G{acute e}nin, J. Appl. Phys. {bold 77}, 5130 (1995)] which analyzes the formation of a ridge at a traveling grain boundary due to stress and capillarity driving forces provides a quantitative description of the growth of the hillocks. In order to test the model, the surface morphology of aluminum thin films deposited on oxidized silicon substrates and annealed at 450{degree}C in argon is investigated; the profiles of thermal hillocks are measured by atomic force microscopy. The comparison shows excellent agreement between modeled and experimental profiles. {copyright}{ital 1996 American Institute of Physics.}

  4. Phosphorous and aluminum gettering in Silicon-Film{trademark} Product II material

    SciTech Connect

    Cotter, J.E.; Barnett, A.M.; Hall, R.B.

    1995-08-01

    Gettering processes are being developed for the Silicon-Film{trademark} Product II solar cell structure. These processes have been developed specifically for films of silicon grown on dissimilar substrates with barrier layers. Gettering with both phosphorous- and aluminum-based processing sequences has resulted in enhancement of minority carrier diffusion length. Long diffusion lengths have allowed the characterization of light trapping in thin films of silicon grown on barrier-coated substrates.

  5. Thin-film transistors with a graphene oxide nanocomposite channel.

    PubMed

    Jilani, S Mahaboob; Gamot, Tanesh D; Banerji, P

    2012-12-04

    Graphene oxide (GO) and graphene oxide-zinc oxide nanocomposites (GO-ZnO) were used as channel materials on SiO(2)/Si to fabricate thin-film transistors (TFT) with an aluminum source and drain. Pure GO-based TFT showed poor field-effect characteristics. However, GO-ZnO-nanocomposite-based TFT showed better field-effect performance because of the anchoring of ZnO nanostructures in the GO matrix, which causes a partial reduction in GO as is found from X-ray photoelectron spectroscopic data. The field-effect mobility of charge carriers at a drain voltage of 1 V was found to be 1.94 cm(2)/(V s). The transport of charge carriers in GO-ZnO was explained by a fluctuation-induced tunneling mechanism.

  6. Single-crystalline aluminum film for ultraviolet plasmonic nanolasers

    NASA Astrophysics Data System (ADS)

    Chou, Bo-Tsun; Chou, Yu-Hsun; Wu, Yen-Mo; Chung, Yi-Cheng; Hsueh, Wei-Jen; Lin, Shih-Wei; Lu, Tien-Chang; Lin, Tzy-Rong; Lin, Sheng-Di

    2016-01-01

    Significant advances have been made in the development of plasmonic devices in the past decade. Plasmonic nanolasers, which display interesting properties, have come to play an important role in biomedicine, chemical sensors, information technology, and optical integrated circuits. However, nanoscale plasmonic devices, particularly those operating in the ultraviolet regime, are extremely sensitive to the metal and interface quality. Thus, these factors have a significant bearing on the development of ultraviolet plasmonic devices. Here, by addressing these material-related issues, we demonstrate a low-threshold, high-characteristic-temperature metal-oxide-semiconductor ZnO nanolaser that operates at room temperature. The template for the ZnO nanowires consists of a flat single-crystalline Al film grown by molecular beam epitaxy and an ultrasmooth Al2O3 spacer layer synthesized by atomic layer deposition. By effectively reducing the surface plasmon scattering and metal intrinsic absorption losses, the high-quality metal film and the sharp interfaces formed between the layers boost the device performance. This work should pave the way for the use of ultraviolet plasmonic nanolasers and related devices in a wider range of applications.

  7. Single-crystalline aluminum film for ultraviolet plasmonic nanolasers

    PubMed Central

    Chou, Bo-Tsun; Chou, Yu-Hsun; Wu, Yen-Mo; Chung, Yi-Cheng; Hsueh, Wei-Jen; Lin, Shih-Wei; Lu, Tien-Chang; Lin, Tzy-Rong; Lin, Sheng-Di

    2016-01-01

    Significant advances have been made in the development of plasmonic devices in the past decade. Plasmonic nanolasers, which display interesting properties, have come to play an important role in biomedicine, chemical sensors, information technology, and optical integrated circuits. However, nanoscale plasmonic devices, particularly those operating in the ultraviolet regime, are extremely sensitive to the metal and interface quality. Thus, these factors have a significant bearing on the development of ultraviolet plasmonic devices. Here, by addressing these material-related issues, we demonstrate a low-threshold, high-characteristic-temperature metal-oxide-semiconductor ZnO nanolaser that operates at room temperature. The template for the ZnO nanowires consists of a flat single-crystalline Al film grown by molecular beam epitaxy and an ultrasmooth Al2O3 spacer layer synthesized by atomic layer deposition. By effectively reducing the surface plasmon scattering and metal intrinsic absorption losses, the high-quality metal film and the sharp interfaces formed between the layers boost the device performance. This work should pave the way for the use of ultraviolet plasmonic nanolasers and related devices in a wider range of applications. PMID:26814581

  8. A method of producing high quality oxide and related films on surfaces

    NASA Technical Reports Server (NTRS)

    Ruckman, Mark W.; Strongin, Myron; Gao, Yongli

    1991-01-01

    Aluminum oxide or aluminum nitride films were deposited on molecular beam epitaxy (MBE) grown GaAS(100) using a novel cryogenic-based reactive thin film deposition technique. The process involves the condensation of molecular oxygen, ammonia, or other gases normally used for reactive thin film deposition on the substrate before the metal is deposited. The metal vapor is deposited into this layer and reacts with the molecular solid to form the desired compound or a precursor that can be thermally decomposed to generate the desired compound. The films produced by this method are free of impurities, and the low temperatures can be used to control the film and interfacial structure. The process can be easily integrated with existing MBE systems. Ongoing research using the same apparatus suggests that photon or electron irradiation could be used to promote the reactions needed to produce the intended material.

  9. Aluminum powder metallurgy processing

    SciTech Connect

    Flumerfelt, J.F.

    1999-02-12

    The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.

  10. Ultraviolet-assisted oxidation and nitridation of hafnium and hafnium aluminum alloys as potential gate dielectrics for metal oxide semiconductor applications

    NASA Astrophysics Data System (ADS)

    Essary, Chad Robert

    The continued miniaturization of silicon-based complimentary metal oxide semiconductor (CMOS) devices is pushing the limits of the silicon dioxide (SiO2) gate dielectric. As the channel widths are decreased to increase packing densities and functionality of new chips, proportional vertical scaling of the dielectric must be maintained to keep constant capacitances. Silicon dioxide is approaching its fundamental limit in which it can be used as the gate dielectric due to high leakage currents resulting from direct tunneling through the layer. In order for the continued use of current CMOS gate design, an alternative material with a higher dielectric constant must be found. Several materials have been proposed but are still not providing the electrical characteristics favorable for use in the devices due to problems with excessive leakage and hysteresis resulting from the quality of the film and oxygen defects. The goal of this study is to create higher quality films at lower processing temperatures with low leakage and less hysteresis than has been achieved with hafnium oxide films. This study first examines the formation of the interfacial layer in pulsed laser deposited hafnium oxide films to understand the kinetics behind its formation. The second section focuses on the oxidation of pulsed laser deposited (PLD) hafnium metal thin films using ultraviolet (UV) assisted post-deposition annealing. Another set of samples was deposited in an ammonia atmosphere in order to incorporate nitrogen into the films. Comparisons of microstructure and stoichiometry of oxidized hafnium and oxy-nitride films were made using x-ray photospectroscopy, variable angle spectroscopic ellipsometry, glancing angle x-ray spectroscopy, x-ray reflectivity, and atomic force microscopy. Analysis of the interface between the films and the silicon substrate was carried out using x-ray reflectivity. The electrical characteristics of the films were characterized using capacitance-voltage and current

  11. Nano-oxide thin films deposited via atomic layer deposition on microchannel plates.

    PubMed

    Yan, Baojun; Liu, Shulin; Heng, Yuekun

    2015-01-01

    Microchannel plate (MCP) as a key part is a kind of electron multiplied device applied in many scientific fields. Oxide thin films such as zinc oxide doped with aluminum oxide (ZnO:Al2O3) as conductive layer and pure aluminum oxide (Al2O3) as secondary electron emission (SEE) layer were prepared in the pores of MCP via atomic layer deposition (ALD) which is a method that can precisely control thin film thickness on a substrate with a high aspect ratio structure. In this paper, nano-oxide thin films ZnO:Al2O3 and Al2O3 were prepared onto varied kinds of substrates by ALD technique, and the morphology, element distribution, structure, and surface chemical states of samples were systematically investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoemission spectroscopy (XPS), respectively. Finally, electrical properties of an MCP device as a function of nano-oxide thin film thickness were firstly studied, and the electrical measurement results showed that the average gain of MCP was greater than 2,000 at DC 800 V with nano-oxide thin film thickness approximately 122 nm. During electrical measurement, current jitter was observed, and possible reasons were preliminarily proposed to explain the observed experimental phenomenon.

  12. Solid propellant exhausted aluminum oxide and hydrogen chloride - Environmental considerations

    NASA Technical Reports Server (NTRS)

    Cofer, W. R., III; Winstead, E. L.; Purgold, G. C.; Edahl, R. A.

    1993-01-01

    Measurements of gaseous hydrogen chloride (HCl) and particulate aluminum oxide (Al2O3) were made during penetrations of five Space Shuttle exhaust clouds and one static ground test firing of a shuttle booster. Instrumented aircraft were used to penetrate exhaust clouds and to measure and/or collect samples of exhaust for subsequent analyses. The focus was on the primary solid rocket motor exhaust products, HCl and Al2O3, from the Space Shuttle's solid boosters. Time-dependent behavior of HCl was determined for the exhaust clouds. Composition, morphology, surface chemistry, and particle size distributions were determined for the exhausted Al2O3. Results determined for the exhaust cloud from the static test firing were complicated by having large amounts of entrained alkaline ground debris (soil) in the lofted cloud. The entrained debris may have contributed to neutralization of in-cloud HCl.

  13. Nitric oxide signaling in aluminum stress in plants.

    PubMed

    He, Huyi; Zhan, Jie; He, Longfei; Gu, Minghua

    2012-07-01

    Nitric oxide (NO) is a ubiquitous signal molecule involved in multiple plant responses to environmental stress. In the recent years, the regulating role of NO on heavy metal toxicity in plants is realized increasingly, but knowledge of NO in alleviating aluminum (Al) toxicity is quite limited. In this article, NO homeostasis between its biosynthesis and elimination in plants is presented. Some genes involved in NO/Al network and their expressions are also introduced. Furthermore, the role of NO in Al toxicity and the functions in Al tolerance are discussed. It is proposed that Al toxicity may disrupt NO homeostasis, leading to endogenous NO concentration being lower than required for root elongation in plants. There are many evidences that pointed out that the exogenous NO treatments improve Al tolerance in plants through activating antioxidative capacity to eliminate reactive oxygen species. Most of the work with respect to NO regulating pathways and functions still has to be done in the future.

  14. Flexible anodized aluminum oxide membranes with customizable back contact materials

    NASA Astrophysics Data System (ADS)

    Nadimpally, B.; Jarro, C. A.; Mangu, R.; Rajaputra, S.; Singh, V. P.

    2016-12-01

    Anodized aluminum oxide (AAO) membranes were fabricated using flexible substrate/carrier material. This method facilitates the use of AAO templates with many different materials as substrates that are otherwise incompatible with most anodization techniques. Thin titanium (Ti) and tungsten (W) layers were employed as interlayer materials. Titanium enhances adhesion. Tungsten not only helps eliminate the barrier layer but also plays a critical role in enabling the use of flexible substrates. The resulting flexible templates provide new, exciting opportunities in photovoltaic and other device applications. CuInSe2 nanowires were electrochemically deposited into porous AAO templates with molybdenum (Mo) as the back contact material. The feasibility of using any material to form a contact with semiconductor nanowires has been demonstrated for the first time enabling new avenues in photovoltaic applications.

  15. Enhanced photocatalytic activity of electrochemically synthesized aluminum oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Pathania, Deepak; Katwal, Rishu; Kaur, Harpreet

    2016-03-01

    In this study, aluminum oxide (Al2O3) nanoparticles (NPs) were synthesized via an electrochemical method. The effects of reaction parameters such as supporting electrolytes, solvent, current and electrolysis time on the shape and size of the resulting NPs were investigated. The Al2O3 NPs were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, thermogravimetric analysis/differential thermal analysis, energy-dispersive X-ray analysis, and ultraviolet-visible spectroscopy. Moreover, the Al2O3 NPs were explored for photocatalytic degradation of malachite green (MG) dye under sunlight irradiation via two processes: adsorption followed by photocatalysis; coupled adsorption and photocatalysis. The coupled process exhibited a higher photodegradation efficiency (45%) compared to adsorption followed by photocatalysis (32%). The obtained kinetic data was well fitted using a pseudo-first-order model for MG degradation.

  16. Transparent nanotubular capacitors based on transplanted anodic aluminum oxide templates.

    PubMed

    Zhang, Guozhen; Wu, Hao; Chen, Chao; Wang, Ti; Wu, Wenhui; Yue, Jin; Liu, Chang

    2015-03-11

    Transparent AlZnO/Al2O3/AlZnO nanocapacitor arrays have been fabricated by atomic layer deposition in anodic aluminum oxide templates transplanted on the AlZnO/glass substrates. A high capacitance density of 37 fF/μm(2) is obtained, which is nearly 5.8 times bigger than that of planar capacitors. The capacitance density almost remains the same in a broad frequency range from 1 kHz to 200 kHz. Moreover, a low leakage current density of 1.7 × 10(-7) A/cm(2) at 1 V has been achieved. The nanocapacitors exhibit an average optical transmittance of more than 80% in the visible range, and thus open the door to practical applications in transparent integrated circuits.

  17. Biodistribution and toxicity of spherical aluminum oxide nanoparticles.

    PubMed

    Park, Eun-Jung; Lee, Gwang-Hee; Yoon, Cheolho; Jeong, Uiseok; Kim, Younghun; Cho, Myung-Haing; Kim, Dong-Wan

    2016-03-01

    With the rapid development of the nano-industry, concerns about their potential adverse health effects have been raised. Thus, ranking accurately their toxicity and prioritizing for in vivo testing through in vitro toxicity test is needed. In this study, we used three types of synthesized aluminum oxide nanoparticles (AlONPs): γ-aluminum oxide hydroxide nanoparticles (γ-AlOHNPs), γ- and α-AlONPs. All three AlONPs were spherical, and the surface area was the greatest for γ-AlONPs, followed by the α-AlONPs and γ-AlOHNPs. In mice, γ-AlOHNPs accumulated the most 24 h after a single oral dose. Additionally, the decreased number of white blood cells (WBC), the increased ratio of neutrophils and the enhanced secretion of interleukin (IL)-8 were observed in the blood of mice dosed with γ-AlOHNPs (10 mg kg(-1)). We also compared their toxicity using four different in vitro test methods using six cell lines, which were derived from their potential target organs, BEAS-2B (lung), Chang (liver), HACAT (skin), H9C2 (heart), T98G (brain) and HEK-293 (kidney). The results showed γ-AlOHNPs induced the greatest toxicity. Moreover, separation of particles was observed in a transmission electron microscope (TEM) image of cells treated with γ-AlOHNPs, but not γ-AlONPs or α-AlONPs. In conclusion, our results suggest that the accumulation and toxicity of AlONPs are stronger in γ-AlOHNPs compared with γ-AlONPs and α-AlONPs owing their low stability within biological system, and the presence of hydroxyl group may be an important factor in determining the distribution and toxicity of spherical AlONPs.

  18. Bonding of sapphire to sapphire by eutectic mixture of aluminum oxide and zirconium oxide

    NASA Technical Reports Server (NTRS)

    Deluca, J. J. (Inventor)

    1975-01-01

    Bonding of an element comprising sapphire, ruby or blue sapphire to another element of such material with a eutectic mixture of aluminum oxide and zirconium oxide is discussed. The bonding mixture may be applied in the form of a distilled water slurry or by electron beam vapor deposition. In one embodiment the eutectic is formed in situ by applying a layer of zirconium oxide and then heating the assembly to a temperature above the eutectic temperature and below the melting point of the material from which the elements are formed. The formation of a sapphire rubidium maser cell utilizing eutectic bonding is shown.

  19. Bonding of sapphire to sapphire by eutectic mixture of aluminum oxide and zirconium oxide

    NASA Technical Reports Server (NTRS)

    Deluca, J. J. (Inventor)

    1979-01-01

    An element comprising sapphire, ruby or blue sapphire can be bonded to another element of such material with a eutectic mixture of aluminum oxide and zirconium oxide. The bonding mixture may be applied in the form of a distilled water slurry or by electron beam vapor deposition. In one embodiment the eutectic is formed in situ by applying a layer of zirconium oxide and then heating the assembly to a temperature above the eutectic temperature and below the melting point of the material from which the elements are formed. The formation of a sapphire rubidium maser cell utilizing eutectic bonding is shown.

  20. Development of Pinhole-Free Amorphous Aluminum Oxide Protective Layers for Biomedical Device Applications.

    PubMed

    Litvinov, Julia; Wang, Yi-Ju; George, Jinnie; Chinwangso, Pawilai; Brankovic, Stanko; Willson, Richard C; Litvinov, Dmitri

    2013-06-15

    This paper describes synthesis of ultrathin pinhole-free insulating aluminum oxide layers for electronic device protection in corrosive liquid environments, such as phosphate buffered saline (PBS) or clinical fluids, to enable emerging biomedical applications such as biomolecular sensors. A pinhole-free 25-nm thick amorphous aluminum oxide layer has been achieved using ultra-high vacuum DC magnetron reactive sputtering of aluminum in oxygen/argon plasma followed by oxygen plasma post-processing. Deposition parameters were optimized to achieve the best corrosion protection of lithographically defined device structures. Electrochemical deposition of copper through the aluminum oxide layers was used to detect the presence (or absence) of pinholes. FTIR, XPS, and spectroscopic ellipsometry were used to characterize the material properties of the protective layers. Electrical resistance of the copper device structures protected by the aluminum oxide layers and exposed to a PBS solution was used as a metric to evaluate the long-term stability of these device structures.

  1. Ultralyophobic oxidized aluminum surfaces exhibiting negligible contact angle hysteresis.

    PubMed

    Hozumi, Atsushi; McCarthy, Thomas J

    2010-02-16

    Ultralyophobic oxidized aluminum surfaces exhibiting negligible contact angle hysteresis for probe liquids were prepared by chemical vapor deposition (CVD) of bis((tridecafluoro-1,1,2,2,-tetrahydrooctyl)-dimethylsiloxy)methylsilane (CF(3)(CF(2))(5)CH(2)CH(2)Si(CH(3))(2)O)(2)SiCH(3)H, (R(F)Si(Me)(2)O)(2)SiMeH). Oxidized aluminum surfaces were prepared by photooxidation/cleaning of sputter-coated aluminum on silicon wafers (Si/Al(Al(2)(O(3)))) using oxygen plasma. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) confirmed that this facile CVD method produces a monolayer with a thickness of 1.1 nm on the Si/Al(Al(2)(O(3))) surface without a discernible change in surface morphology. After monolayer deposition, the hydrophilic Si/Al(Al(2)(O(3))) surface became both hydrophobic and oleophobic and exhibited essentially no contact angle hysteresis for water and n-hexadecane (advancing/receding contact angles (theta(A)/theta(R)) = 110 degrees/109 degrees and 52 degrees/50 degrees, respectively). Droplets move very easily on this surface and roll off of slightly tilted surfaces, independently of the contact angle (which is a practical definition of ultralyophobic). A conventional fluoroalkylsilane monolayer was also prepared from 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (CF(3)(CF(2))(7)CH(2)CH(2)Si(OCH(3))(3), R(F)Si(OMe)(3)) for comparison. The theta(A)/theta(R) values for water and n-hexadecane are 121 degrees/106 degrees and 76 degrees/71 degrees, respectively. The larger hysteresis values indicate the "pinning" of probe liquids, even though advancing contact angles are larger than those of the (R(F)Si(Me)(2)O)(2)SiMeH-derived monolayers. The (R(F)Si(Me)(2)O)(2)SiMeH-derived monolayers have excellent hydrolytic stability in water. We propose that the (R(F)Si(Me)(2)O)(2)SiMeH-derived monolayers are flexible and liquidlike and that drops in contact with these surfaces experience very low energy barriers between metastable states, leading to the

  2. Single-Phase Rare-Earth Oxide/Aluminum Oxide Glasses

    NASA Technical Reports Server (NTRS)

    Weber, J. K. Richard; Abadie, John G.; Hixson, April D.; Nordine, Paul C.

    2006-01-01

    Glasses that comprise rare-earth oxides and aluminum oxide plus, optionally, lesser amounts of other oxides, have been invented. The other oxide(s) can include SiO2, B2O3, GeO2, and/or any of a variety of glass-forming oxides that have been used heretofore in making a variety of common and specialty glasses. The glasses of the invention can be manufactured in bulk single-phase forms to ensure near uniformity in optical and mechanical characteristics, as needed for such devices as optical amplifiers, lasers, and optical waveguides (including optical fibers). These glasses can also be formulated to have high indices of refraction, as needed in some of such devices.

  3. Anodized aluminum oxide-based capacitance sensors for the direct detection of DNA hybridization.

    PubMed

    Kang, Bongkeun; Yeo, Unjin; Yoo, Kyung-Hwa

    2010-03-15

    We fabricated a capacitance sensor based on an anodized aluminum oxide (AAO) nanoporous structure to detect DNA hybridization. We utilized Au film deposited on the surface of the AAO membrane and Au nanowires infiltrating the nanopores as the top and bottom electrodes, respectively. When completely complementary target DNA molecules were added to the sensor-immobilized DNA molecule probes, the capacitance was reduced; with a concentration of 1pM, the capacitance decreased by approximately 10%. We measured the capacitance change for different concentrations of the target DNA solution. A linear relationship was found between the capacitance change and DNA concentration on a semi-logarithmic scale. We also investigated the possibility of detecting DNA molecules with a single-base mismatch to the probe DNA molecule. In contrast to complementary target DNA molecules, the addition of one-base mismatch DNA molecules caused no significant change in capacitance, demonstrating that DNA hybridization was detected with single nucleotide polymorphism sensitivity.

  4. Enhanced Elastic Modulus of Regenerated Silk Fibroin by Geometric Confinement in Anodized Aluminum Oxide Templates

    NASA Astrophysics Data System (ADS)

    Li, Jiankang; Li, Liang

    2017-02-01

    Geometric confinement is a promising method for the reconstruction of silk fibroin to form diversified structures with excellent mechanical properties. To accomplish geometric confinement, a water vapor assistant embossing process is used with porous anodic aluminum oxide templates, yielding silk fibroin nanopillars with diameters ranging from 40 nm to 130 nm. The elastic modulus of the regenerated silk fibroin nanopillars is investigated with atomic force microscopy nanoindentation analysis. Compared to films with the same treatment conditions, geometric confinement provided a twofold increase in elastic modulus in embossed silk fibroin nanopillars, indicating that β-sheet crystal ordering occurred during the water vapor assistant embossing process. These results demonstrate the feasibility and mechanical property enhancement of the embossing method to fabricate silk nanostructures, and will be useful in designing miniaturized devices.

  5. High quality oxide films on substrates

    DOEpatents

    Ruckman, Mark W.; Strongin, Myron; Gao, Yong L.

    1994-01-01

    A method for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material.

  6. High quality oxide films on substrates

    DOEpatents

    Ruckman, M.W.; Strongin, M.; Gao, Y.L.

    1994-02-01

    A method is described for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material. 4 figures.

  7. Measurement of quasiparticle transport in aluminum films using tungsten transition-edge sensors

    SciTech Connect

    Yen, J. J. Shank, B.; Cabrera, B.; Moffatt, R.; Redl, P.; Young, B. A.; Tortorici, E. C.; Brink, P. L.; Cherry, M.; Tomada, A.; Kreikebaum, J. M.

    2014-10-20

    We report on experimental studies of phonon sensors which utilize quasiparticle diffusion in thin aluminum films connected to tungsten transition-edge-sensors (TESs) operated at 35 mK. We show that basic TES physics and a simple physical model of the overlap region between the W and Al films in our devices enables us to accurately reproduce the experimentally observed pulse shapes from x-rays absorbed in the Al films. We further estimate quasiparticle loss in Al films using a simple diffusion equation approach. These studies allow the design of phonon sensors with improved performance.

  8. Cytotoxicity of cultured macrophages exposed to antimicrobial zinc oxide (ZnO) coatings on nanoporous aluminum oxide membranes.

    PubMed

    Petrochenko, Peter E; Skoog, Shelby A; Zhang, Qin; Comstock, David J; Elam, Jeffrey W; Goering, Peter L; Narayan, Roger J

    2013-01-01

    Zinc oxide (ZnO) is a widely used commercial material that is finding use in wound healing applications due to its antimicrobial properties. Our study demonstrates a novel approach for coating ZnO with precise thickness control onto 20 nm and 100 nm pore diameter anodized aluminum oxide using atomic layer deposition (ALD). ZnO was deposited throughout the nanoporous structure of the anodized aluminum oxide membranes. An 8 nm-thick coating of ZnO, previously noted to have antimicrobial properties, was cytotoxic to cultured macrophages. After 48 h, ZnO-coated 20 nm and 100 nm pore anodized aluminum oxide significantly decreased cell viability by ≈65% and 54%, respectively, compared with cells grown on uncoated anodized aluminum oxide membranes and cells grown on tissue culture plates. Pore diameter (20-200 nm) did not influence cell viability.

  9. [Studies of effects of aluminum oxide nanoparticles after intragastric administration].

    PubMed

    Shumakova, A A; Tananova, O N; Arianova, E A; Mal'tsev, G Iu; Trushina, É N; Mustafina, O K; Guseva, G V; Trusov, N V; Soto, S Kh; Sharanova, N É; Selifanov, A V; Gmoshinskiĭ, I V; Khotimchenko, S A

    2012-01-01

    Growing Wistar rats received intragastrically nanoparticles (NPs) of aluminum oxide (Al2O3) daily during 28 days at doses of 1 or 100 mg per kg body mass. There were studied body mass of animals, relative mass of internals, rate of protein macromolecules absorption in the gut, oxidative damage of DNA, pool of tissue thiols, activity of hepatic enzymes of xenobiotic detoxication system, biochemical and hematological blood indices, stability of lysosome membranes, condition of antioxidant defense system, apoptosis of hepatocytes. Conducted experiments didn't reveal any marked toxic action of Al2O3 NPs on rats after 28 days of administration both in high and low dose. Among effects probably related to NPs influence on animals there were lowering of relative liver and lung masses, decrease of hepatic thiol pool, activity of CYP1A1 isoform in liver and glutathione reductase in erythrocytes, increase of diene conjugates of fatty acids in blood plasma. Said shifts were small in magnitude, didn't come out of margins of physiological norm and didn't show any distinct relation to NPs dose. However considering great importance of this nanomaterial as probable environmental contaminant the studies of it's toxicity must be continued in conditions of low doses (less than 1 mg per kg body mass) for long period of time.

  10. Surface treatment of aluminum alloy at room temperature with titanium-nitride films by dynamic mixing

    NASA Astrophysics Data System (ADS)

    Sato, T.; Ohata, K.; Asahi, N.; Ono, Y.; Oka, Y.; Hashimoto, I.; Arimatsu, K.

    Titanium-nitride coating films were prepared on aluminum alloy plates at room temperature with simultaneous ion implantation and metal vapor deposition (dynamic mixing) by using a high current ion source. The films were analysed by means of Auger electron spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The results showed the presence of small amount of oxygen and carbon impurities due to a high current density (0.5-1.0 mA/cm 2) of the nitrogen beam (energy: 20 keV). Films of 1.2 μm thickness showed uniform composition. Titanium-nitride coated aluminum alloy (film thickness: 15 μm) was ten times harder than the untreated one. The coated plate was examined by a pin-on-disc wear tester. The results showed better wear properties.

  11. Growing aluminum nitride films by Plasma-Enhanced Atomic Layer Deposition at low temperatures

    NASA Astrophysics Data System (ADS)

    Tarala, V. A.; Altakhov, A. S.; Martens, V. Ya; Lisitsyn, S. V.

    2015-11-01

    Aluminum nitride films have been grown by Plasma-Enhanced Atomic Layer Deposition method. It was found that at temperatures of 250 °C and 280 °C increase of the plasma exposure step duration over 6 s, as well as increase of reactor purge step duration over 1 s does not affect the growth rate, however, it affects the microstructure of the films. It was found that crystalline aluminum nitride films deposit with plasma exposure duration over 10 s and the reactor purging over 10 s. When the temperature drops the increase of reactor purge step duration and plasma exposure step duration over 20 s is required for crystalline AlN film growth.

  12. Self-ordered anodic aluminum oxide formed by H2SO4 hard anodization.

    PubMed

    Schwirn, Kathrin; Lee, Woo; Hillebrand, Reinald; Steinhart, Martin; Nielsch, Kornelius; Gösele, Ulrich

    2008-02-01

    The self-ordering of nanoporous anodic aluminum oxide (AAO) in the course of the hard anodization (HA) of aluminum in sulfuric acid (H2SO4) solutions at anodization voltages ranging from 27 to 80 V was investigated. Direct H2SO4-HA yielded AAOs with hexagonal pore arrays having interpore distances D(int) ranging from 72 to 145 nm. However, the AAOs were mechanically unstable and cracks formed along the cell boundaries. Therefore, we modified the anodization procedure previously employed for oxalic acid HA (H2C2O4-HA) to suppress the development of cracks and to fabricate mechanically robust AAO films with D(int) values ranging from 78 to 114 nm. Image analyses based on scanning electron micrographs revealed that at a given anodization voltage the self-ordering of nanopores as well as D(int) depend on the current density (i.e., the electric field strength at the bottoms of the pores). Moreover, periodic oscillations of the pore diameter formed at anodization voltages in the range from 27 to 32 V, which are reminiscent of structures originating from the spontaneous growth of periodic fluctuations, such as topologies resulting from Rayleigh instabilities.

  13. Aluminum surface layer strengthening using intense pulsed beam radiation of substrate film system

    NASA Astrophysics Data System (ADS)

    Klopotov, A. A.; Ivanov, Yu F.; Vlasov, V. A.; Kondratyuk, A. A.; Teresov, A. D.; Shugurov, V. V.; Petrikova, E. A.

    2016-11-01

    The paper presents formation of the substrate film system (Zr-Ti-Cu/Al) by electric arc spraying of cathode having the appropriate composition. It is shown that the intense beam radiation of the substrate film system is accompanied by formation of the multi-phase state, the microhardness of which exceeds the one of pure A7 aluminum by ≈4.5 times.

  14. Corrosion-electrochemical properties of the anodic oxide films formed on aluminum in a chloride-nitrate melt in a 0.5 M Aqueous NaCl solution

    NASA Astrophysics Data System (ADS)

    Elshina, L. A.; Malkov, V. B.; Kudyakov, V. Ya.; Gnedenkov, S. V.; Sinebryukhov, S. L.; Egorkin, V. S.; Mashtalyar, D. V.

    2014-02-01

    The corrosion-electrochemical behavior of aluminum is studied in a chloride-nitrate melt containing 50 wt % eutectic mixture of cesium and sodium chlorides and 50 wt % sodium nitrate in the temperature range 790-900 K in an argon atmosphere.

  15. Tris-(8-hydroxyquinoline)aluminum thin film as ETL in efficient green phosphorescent OLEDs

    NASA Astrophysics Data System (ADS)

    Thangaraju, K.; Kim, Yun-Hi; Kwon, Soon-Ki

    2013-02-01

    Tris-(8-hydroxyquinoline)aluminum thin film as ETL in green phosphorescent OLEDs improves the device performances to a maximum of 34.2 cd/A, 11.3% with the maximum brightness of 63,150 cd/m2 and broadens the device emission in yellow-green region suitable in the white OLEDs for the lighting applications.

  16. Low Temperature Reactive Sputtering of Thin Aluminum Nitride Films on Metallic Nanocomposites

    PubMed Central

    Ramadan, Khaled Sayed Elbadawi; Evoy, Stephane

    2015-01-01

    Piezoelectric aluminum nitride thin films were deposited on aluminum-molybdenum (AlMo) metallic nanocomposites using reactive DC sputtering at room temperature. The effect of sputtering parameters on film properties was assessed. A comparative study between AlN grown on AlMo and pure aluminum showed an equivalent (002) crystallographic texture. The piezoelectric coefficients were measured to be 0.5±0.1 C m-2 and 0.9±0.1 C m-2, for AlN deposited on Al/0.32Mo and pure Al, respectively. Films grown onto Al/0.32Mo however featured improved surface roughness. Roughness values were measured to be 1.3nm and 5.4 nm for AlN films grown on AlMo and on Al, respectively. In turn, the dielectric constant was measured to be 8.9±0.7 for AlN deposited on Al/0.32Mo seed layer, and 8.7±0.7 for AlN deposited on aluminum; thus, equivalent within experimental error. Compatibility of this room temperature process with the lift-off patterning of the deposited AlN is also reported. PMID:26193701

  17. Low Temperature Reactive Sputtering of Thin Aluminum Nitride Films on Metallic Nanocomposites.

    PubMed

    Ramadan, Khaled Sayed Elbadawi; Evoy, Stephane

    2015-01-01

    Piezoelectric aluminum nitride thin films were deposited on aluminum-molybdenum (AlMo) metallic nanocomposites using reactive DC sputtering at room temperature. The effect of sputtering parameters on film properties was assessed. A comparative study between AlN grown on AlMo and pure aluminum showed an equivalent (002) crystallographic texture. The piezoelectric coefficients were measured to be 0.5±0.1 C m(-2) and 0.9±0.1 C m(-2), for AlN deposited on Al/0.32Mo and pure Al, respectively. Films grown onto Al/0.32Mo however featured improved surface roughness. Roughness values were measured to be 1.3nm and 5.4 nm for AlN films grown on AlMo and on Al, respectively. In turn, the dielectric constant was measured to be 8.9±0.7 for AlN deposited on Al/0.32Mo seed layer, and 8.7±0.7 for AlN deposited on aluminum; thus, equivalent within experimental error. Compatibility of this room temperature process with the lift-off patterning of the deposited AlN is also reported.

  18. Oxidation of ligand-protected aluminum clusters: An ab initio molecular dynamics study

    SciTech Connect

    Alnemrat, Sufian; Hooper, Joseph P.

    2014-03-14

    We report Car-Parrinello molecular dynamics simulations of the oxidation of ligand-protected aluminum clusters that form a prototypical cluster-assembled material. These clusters contain a small aluminum core surrounded by a monolayer of organic ligand. The aromatic cyclopentadienyl ligands form a strong bond with surface Al atoms, giving rise to an organometallic cluster that crystallizes into a low-symmetry solid and is briefly stable in air before oxidizing. Our calculations of isolated aluminum/cyclopentadienyl clusters reacting with oxygen show minimal reaction between the ligand and O{sub 2} molecules at simulation temperatures of 500 and 1000 K. In all cases, the reaction pathway involves O{sub 2} diffusing through the ligand barrier, splitting into atomic oxygen upon contact with the aluminum, and forming an oxide cluster with aluminum/ligand bonds still largely intact. Loss of individual aluminum-ligand units, as expected from unimolecular decomposition calculations, is not observed except following significant oxidation. These calculations highlight the role of the ligand in providing a steric barrier against oxidizers and in maintaining the large aluminum surface area of the solid-state cluster material.

  19. Nonlithographic nanopatterning through anodic aluminum oxide template and selective growth of highly ordered GaN nanostructures

    NASA Astrophysics Data System (ADS)

    Wang, Y. D.; Zang, K. Y.; Chua, S. J.

    2006-09-01

    Ordered GaN nanostructures, i.e., nanopore and nanodot arrays, have been demonstrated by combining a nonlithographic nanopatterning technique and nanoscale selective epitaxial growth. Hexagonal-close-packed nanopore arrays were fabricated in GaN surfaces and SiO2 surfaces on GaN films by inductively coupled plasma etching using anodic aluminum oxide templates as etching masks. Selective area growth through nanopores in SiO2 by metal organic chemical vapor deposition results in ordered GaN nanodot arrays with an average dot diameter and height of 60 and 100nm, respectively. The diameter and density of the GaN nanopore arrays and nanodot arrays are controlled by that of the anodic aluminum oxide template, which can be tuned in a wide range by controlling the anodization conditions. Applying anodic aluminum oxide as an etching mask provides an effective nonlithographic and free of foreign catalysts method to fabricate ordered and dense nitride nanostructures for either bottom-up or top-down technique in the application of high efficiency nitride light emitting diodes.

  20. Evaluation of genotoxic effects of oral exposure to aluminum oxide nanomaterials in rat bone marrow.

    PubMed

    Balasubramanyam, A; Sailaja, N; Mahboob, M; Rahman, M F; Misra, S; Hussain, Saber M; Grover, Paramjit

    2009-05-31

    Nanomaterials have novel properties and functions because of their small size. The unique nature of nanomaterials may be associated with potentially toxic effects. The aim of this study was to evaluate the in vivo genotoxicity of rats exposed with Aluminum oxide nanomaterials. Hence in the present study, the genotoxicity of Aluminum oxide nanomaterials (30 and 40 nm) and its bulk material was studied in bone marrow of female Wistar rats using chromosomal aberration and micronucleus assays. The rats were administered orally with the doses of 500, 1000 and 2000 mg/kg bw. Statistically significant genotoxicity was observed with Aluminum oxide 30 and 40 nm with micronucleus as well as chromosomal aberration assays. Significantly (p < 0.05 or p < 0.001) increased frequency of MN was observed with 1000 and 2000 mg/kg bw dose levels of Aluminum oxide 30 nm (9.4 +/- 1.87 and 15.2 +/- 2.3, respectively) and Aluminum oxide 40 nm (8.1 +/- 1.8 and 13.9 +/- 2.21, respectively) over control (2.5 +/- 0.7) at 30 h. Likewise, at 48 h sampling time a significant (p < 0.05 or p < 0.001) increase in frequency of MN was evident at 1000 and 2000 mg/kg bw dose levels of Aluminum oxide 30 nm (10.6 +/- 1.68 and 16.6 +/- 2.66, respectively) and Aluminum oxide 40 nm (9.0 +/- 1.38 and 14.7 +/- 1.68, respectively) compared to control (1.8 +/- 0.75). Significantly increased frequencies (p < 0.05 or p < 0.001) of chromosomal aberrations were observed with Aluminum oxide 30 nm (1000 and 2000 mg/kg bw) and Aluminum oxide 40 nm (2000 mg/kg bw) in comparison to control at 18 and 24 h. Further, since there is need for information on the toxicokinetics of nanomaterials, determination of these properties of the nanomaterials was carried out in different tissues, urine and feces using inductively coupled plasma mass spectrometry (ICP-MS). A significant size dependent accumulation of Aluminum oxide nanomaterials occurred in different tissues, urine and feces of rats as shown by ICP-MS data. The results

  1. Nanoporous Pirani sensor based on anodic aluminum oxide

    NASA Astrophysics Data System (ADS)

    Jeon, Gwang-Jae; Kim, Woo Young; Shim, Hyun Bin; Lee, Hee Chul

    2016-09-01

    A nanoporous Pirani sensor based on anodic aluminum oxide (AAO) is proposed, and the quantitative relationship between the performance of the sensor and the porosity of the AAO membrane is characterized with a theoretical model. The proposed Pirani sensor is composed of a metallic resistor on a suspended nanoporous membrane, which simultaneously serves as the sensing area and the supporting structure. The AAO membrane has numerous vertically-tufted nanopores, resulting in a lower measurable pressure limit due to both the increased effective sensing area and the decreased effective thermal loss through the supporting structure. Additionally, the suspended AAO membrane structure, with its outer periphery anchored to the substrate, known as a closed-type design, is demonstrated using nanopores of AAO as an etch hole without a bulk micromachining process used on the substrate. In a CMOS-compatible process, a 200 μm × 200 μm nanoporous Pirani sensor with porosity of 25% was capable of measuring the pressure from 0.1 mTorr to 760 Torr. With adjustment of the porosity of the AAO, the measurable range could be extended toward lower pressures of more than one decade compared to a non-porous membrane with an identical footprint.

  2. Microfluidic DNA extraction using a patterned aluminum oxide membrane

    NASA Astrophysics Data System (ADS)

    Kim, Jungkyu; Gale, Bruce K.

    2006-01-01

    A DNA extraction system was designed and fabricated using an AOM (aluminum oxide membrane) with 200 nm pores and PDMS microfluidic channels. The membrane was patterned using soft lithography techniques and SU-8 photolithography on the membrane. After making the pattern with SU-8, the AOM was observed using an SEM (scanning electro microscope) to verify the AOM structure was not damaged. From the SEM images, the AOM structure was not different after modification with SU-8. To complete the system, a PDMS mold for the microfluidic channels was made by soft lithography. Using the SU-8 mold, PDMS microchannels were cast using PDMS with a low polymer to curing agent ratio to provide adhesion between the patterned membrane and microfluidic channel. Then, the patterned membrane was sandwiched between PDMS microfluidic channels in a parallel format. The completed system was tested with 10ug of Lambda DNA mixed with the fluorescent dye SYBR Green I. Following DNA extraction, the surface of each well was examined with fluorescence microscopy while embedded in the microfluidic system. Extracted and immobilized DNA on the AOM was observed in almost every separation well. This microsystem, referred to as a membrane-on-a-chip, has potential applications in high-throughput DNA extraction and analysis, with the possibility of being integrated into polymer-based microfluidic systems.

  3. Highly ordered carbon nanotubes based on porous aluminum oxide.

    PubMed

    Pan, H; Gao, H; Lim, S H; Feng, Y P; Lin, J

    2004-11-01

    Highly ordered carbon nanotubes (CNTs) are widely pursued due to their unique properties. Anodic aluminum oxide (AAO) exhibits great possibility for this purpose. Here, CNTs based on AAO templates were produced using acetylene or ethylene as the hydrocarbon sources with or without the presence of Co catalysts. CNTs grown on the Co-embedded AAO samples were normally confined within the nanopores of the AAO template. It was found that C2H4 normally requires 100 degrees C higher pyrolysis temperature than C2H2 under otherwise identical conditions. The pyrolysis temperature is greatly reduced with the presence of Co catalysts. CNTs can grow out of the nanopores if Co particles are present at the bottom of the nanopores, and if the nanopores are short in length or large in diameter. The graphitization of AAO-template grown CNTs was studied by Raman spectroscopy. CNTs produced from ethylene are generally better in graphitization than those from acetylene, and CNTs grown with the presence of Co catalysts deposited at the bottom of nanopores are better than those without Co catalysts or with Co catalysts coated on the entire inner wall of nanopores. The growth temperature is found not to play a critical role in graphitization.

  4. Molecular scale assessment of methylarsenic sorption on aluminum oxide.

    PubMed

    Shimizu, Masayuki; Ginder-Vogel, Matthew; Parikh, Sanjai J; Sparks, Donald L

    2010-01-15

    Methylated forms of arsenic (As), monomethylarsenate (MMA) and dimethylarsenate (DMA), have historically been used as herbicides and pesticides. Because of their large application to agriculture fields and the toxicity of MMA and DMA, the sorption of methylated As to soil constituents requires investigation. MMA and DMA sorption on amorphous aluminum oxide (AAO) was investigated using both macroscopic batch sorption kinetics and molecular scale extended X-ray absorption fine structure (EXAFS) and Fourier transform infrared (FTIR) spectroscopic techniques. Sorption isotherm studies revealed sorption maxima of 0.183, 0.145, and 0.056 mmol As/mmol Al for arsenate (As(V)), MMA, and DMA, respectively. In the sorption kinetics studies, 100% of added As(V) was sorbed within 5 min, while 78% and 15% of added MMA and DMA were sorbed, respectively. Desorption experiments, using phosphate as a desorbing agent, resulted in 30% release of absorbed As(V), while 48% and 62% of absorbed MMA and DMA, respectively, were released. FTIR and EXAFS studies revealed that MMA and DMA formed mainly bidentate binuclear complexes with AAO. On the basis of these results, it is proposed that increasing methyl group substitution results in decreased As sorption and increased As desorption on AAO.

  5. Molecular Scale Assessment of Methylarsenic Sorption on Aluminum Oxide

    SciTech Connect

    Shimizu, M.; Ginder-Vogel, M; Parikh, S; Sparks, D

    2010-01-01

    Methylated forms of arsenic (As), monomethylarsenate (MMA) and dimethylarsenate (DMA), have historically been used as herbicides and pesticides. Because of their large application to agriculture fields and the toxicity of MMA and DMA, the sorption of methylated As to soil constituents requires investigation. MMA and DMA sorption on amorphous aluminum oxide (AAO) was investigated using both macroscopic batch sorption kinetics and molecular scale extended X-ray absorption fine structure (EXAFS) and Fourier transform infrared (FTIR) spectroscopic techniques. Sorption isotherm studies revealed sorption maxima of 0.183, 0.145, and 0.056 mmol As/mmol Al for arsenate (As{sup V}), MMA, and DMA, respectively. In the sorption kinetics studies, 100% of added As{sup V} was sorbed within 5 min, while 78% and 15% of added MMA and DMA were sorbed, respectively. Desorption experiments, using phosphate as a desorbing agent, resulted in 30% release of absorbed As{sup V}, while 48% and 62% of absorbed MMA and DMA, respectively, were released. FTIR and EXAFS studies revealed that MMA and DMA formed mainly bidentate binuclear complexes with AAO. On the basis of these results, it is proposed that increasing methyl group substitution results in decreased As sorption and increased As desorption on AAO.

  6. Stability of (bio)functionalized porous aluminum oxide.

    PubMed

    Debrassi, Aline; Ribbera, Angela; de Vos, Willem M; Wennekes, Tom; Zuilhof, Han

    2014-02-11

    Porous aluminum oxide (PAO), a nanostructured support for, among others, culturing microorganisms, was chemically modified in order to attach biomolecules that can selectively interact with target bacteria. We present the first comprehensive study of monolayer-modified PAO using conditions that are relevant to microbial growth with a range of functional groups (carboxylic acid, α-hydroxycarboxylic acid, alkyne, alkene, phosphonic acid, and silane). Their stability was initially assessed in phosphate-buffered saline (pH 7.0) at room temperature. The most stable combination (PAO with phosphonic acids) was further studied over a range of physiological pHs (4-8) and temperatures (up to 80 °C). Varying the pH had no significant effect on the stability, but it gradually decreased with increasing temperature. The stability of phosphonic acid-modified PAO surfaces was shown to depend strongly on the other terminal group of the monolayer structure: in general, hydrophilic monolayers were less stable than hydrophobic monolayers. Finally, an alkyne-terminated PAO surface was reacted with an azide-linked mannose derivative. The resulting mannose-presenting PAO surface showed the clearly increased adherence of a mannose-binding bacterium, Lactobacillus plantarum, and also allowed for bacterial outgrowth.

  7. Surface chemistry and corrosion behavior of aluminum-copper systems: Air-formed films to complex conversion coatings

    NASA Astrophysics Data System (ADS)

    Chidambaram, Devicharan

    Understanding the mechanism of corrosion inhibition by carcinogenic chromates is critical to the development of environmentally safe coatings containing benign chromate substitutes. An integrated approach to correlate the surface chemistry and corrosion behavior of a wide range of systems has been undertaken. Electrochemical behavior was studied by open circuit potential (OCP) measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). Surface chemistry was studied using variable-angle X-ray photoelectron spectroscopy (VAXPS), X-ray absorption near edge spectroscopy (XANES), secondary ion mass spectroscopy (SIMS), infrared spectroscopy and synchrotron infrared micro spectroscopy (SIRMS) and Raman spectroscopy. Using SIRMS, the ASTM recommended acetone degreasing was shown to initiate pitting of AA2024-T3 via photochemical formation of acetic acid. Due to the known tendency for photoreduction of Cr6+(3d0) following soft X-ray dosage during XPS, a novel method has been developed to prevent this reduction. This method yields, for the first time, an accurate determination of the Cr6+ content of a CCC. The pretreatment of the alloy prior to conversion coating has been shown to have significant influence on the surface intermetallic distribution, composition and corrosion resistance of the initial oxide film and subsequent conversion coating. AlconoxRTM pretreatment was found to result in a highly protective surface film that inhibits the subsequent formation of CCC. The study also shows that coupling of the alloy to platinum during the bromate pretreatment increases the corrosion resistance of the subsequently formed CCC by over an order of magnitude due to reduction in surface copper content. Adsorption of chromate ion on the passive oxide film formed on the metal surface was observed to induce fixed negative charges that inhibit chloride ingress on planar surfaces. While deprotonation of the aluminum hydroxide film by chromate was

  8. Measurements of material properties for solar cells. [aluminum film and KAPTON

    NASA Technical Reports Server (NTRS)

    Castle, J. G., Jr.

    1978-01-01

    Measurements on two candidate materials for space flight are reported. The observed optical transmittance of aluminum films vapor deposited on fused quartz showed anomalously high transmittance thru 400 A and 600 A and showed an effective skin depth of 110 A in the latter part of the 1000 A thickness. KAPTON films are shown by their optical transmission spectra to have an energy gap for electron excitation of approximately 2.5 eV, which value depends on the thickness as manufactured. The resistance of KAPTON film to ionizing radiation is described by their optical spectra and their electron spin resonance spectra.

  9. Dielectric properties of aluminum silver alloy thin films in optical frequency range

    SciTech Connect

    Yang Guang; Sun Jingbo; Zhou Ji

    2011-06-15

    The dielectric properties of direct current (dc) magnetron sputtering aluminum silver alloy films in optical frequency have been quantitatively studied by variable angle spectroscopic ellipsometry. The structure and surface topography of the alloy films were characterized using scanning probe microscopy and x-ray diffraction. The Drude-Lorentz model was used to simulate the dielectric function of Al-Ag alloy films. Meanwhile, the effective medium theory has been utilized for the treatment of surface roughness. We found that the interband transition around 1.5 eV can be shifted through a variable annealing temperature and a changeable silver percentage of Al-Ag alloys.

  10. Electro-deposition of superconductor oxide films

    DOEpatents

    Bhattacharya, Raghu N.

    2001-01-01

    Methods for preparing high quality superconducting oxide precursors which are well suited for further oxidation and annealing to form superconducting oxide films. The method comprises forming a multilayered superconducting precursor on a substrate by providing an electrodeposition bath comprising an electrolyte medium and a substrate electrode, and providing to the bath a plurality of precursor metal salts which are capable of exhibiting superconducting properties upon subsequent treatment. The superconducting precursor is then formed by electrodepositing a first electrodeposited (ED) layer onto the substrate electrode, followed by depositing a layer of silver onto the first electrodeposited (ED) layer, and then electrodepositing a second electrodeposited (ED) layer onto the Ag layer. The multilayered superconducting precursor is suitable for oxidation at a sufficient annealing temperature in air or an oxygen-containing atmosphere to form a crystalline superconducting oxide film.

  11. Investigation of contamination of thin-film aluminum filters by MMH-NTO plumes exposed to UV radiation

    NASA Astrophysics Data System (ADS)

    Gupta, Vaibhav; Wieman, Seth; Didkovsky, Leonid; Haiges, Ralf; Yao, Yuhan; Wu, Wei; Gruntman, Mike; Erwin, Dan

    2015-09-01

    Thin-film aluminum filters degrade in space with significant reduction of their Extreme Ultraviolet (EUV) transmission. This degradation was observed on the EUV Spectrophotometer (ESP) onboard the Solar Dynamics Observatory's EUV Variability Experiment and the Solar EUV Monitor (SEM) onboard the Solar and Heliospheric Observatory. One of the possible causes for deterioration of such filters over time is contamination of their surfaces from plumes coming from periodic firing of their satellite's Monomethylhydrazine (MMH) - Nitrogen Tetroxide (NTO) thrusters. When adsorbed by the filters, the contaminant molecules are exposed to solar irradiance and could lead to two possible compositions. First, they could get polymerized leading to a permanent hydrocarbon layer buildup on the filter's surface. Second, they could accelerate and increase the depth of oxidation into filter's bulk aluminum material. To study the phenomena we experimentally replicate contamination of such filters in a simulated environment by MMH-NTO plumes. We apply, Scanning Electron Microscopy and X-Ray photoelectron spectroscopy to characterize the physical and the chemical changes on these contaminated sample filter surfaces. In addition, we present our first analysis of the effects of additional protective layer coatings based on self-assembled carbon monolayers for aluminum filters. This coverage is expected to significantly decrease their susceptibility to contamination and reduce the overall degradation of filter-based EUV instruments over their mission life.

  12. Texture evolution in aluminum-copper thin films

    NASA Astrophysics Data System (ADS)

    Murray, Conal Eugene

    A synergistic approach of complementary characterization techniques was used to investigate the effects of deposition surface chemistry, morphology and temperature on the microstructure of sputter deposited Al-0.5%wt. Cu thin films. X-ray texture measurements and scanning electron microscopy (SEM) of Al(Cu) films with thicknesses ranging from 10 nm to 500 nm deposited on various interlevel dielectric (ILD) layers revealed three regimes of texture corresponding to microstructural changes within the films. The faceting of Al(Cu) islands represented the first semblance of texture, which was offset from the substrate normal. As Al(Cu) islands coalesced into continuous films, (111) texture was improved until extensive faceting on grain surfaces produced offset texture. Although the existence of Al2CU precipitates, as evidenced by scanning transmission electron microscopy (STEM), altered grain size distributions within the 500 nm Al(Cu) films, offset (111) texture was not appreciably affected. The presence of 20 nm Ti barrier layers on ILD's modified the growth of Al and Al(Cu) films by providing an epitaxial template for the AI atoms to follow. Results from cross-sectional TEM and analytical electron microscopy (AEM) indicated that a TiAl3 reaction layer formed between the sputter deposited Al/Ti films deposited at temperatures as low as 150°C. The microstructure of the resultant Al(Cu) films was highly dependent on the ILD topography, which was not modified by the Ti layer. On ILD's with RMS roughnesses less than 2 nm 500 nm Al(Cu) films with pronounced (111) texture were produced with no discernible offset. For rougher ILD surfaces, a model that incorporated the underlying ILD morphology, as characterized by atomic force microscopy (AFM), was created to quantitatively describe the observed offset in Al (111) texture.

  13. Scanning Photoacoustic Microscopy of Aluminum with Aluminum Oxide, Roughness Standards, and Rubber

    DTIC Science & Technology

    1985-07-10

    nickel-based ( 713C ) alloy turbine blade (Fig. 20), differences between the coated and uncoated regions are clearly evident. In Figs. 21-25, we present...aluminum alloy . A detailed description is given in Ref. 7. 3. Composite optical and SPAM micrographs of a 400 x 14 400 point region of an aluminum... alloy containing fatigue cracks which are apparently smaller in length than our present detection capability (0 30Pm). A detailed description is given in

  14. Atomic layer deposition as pore diameter adjustment tool for nanoporous aluminum oxide injection molding masks.

    PubMed

    Miikkulainen, Ville; Rasilainen, Tiina; Puukilainen, Esa; Suvanto, Mika; Pakkanen, Tapani A

    2008-05-06

    The wetting properties of polypropylene (PP) surfaces were modified by adjusting the dimensions of the surface nanostructure. The nanostructures were generated by injection molding with nanoporous anodized aluminum oxide (AAO) as the mold insert. Atomic layer deposition (ALD) of molybdenum nitride film was used to control the pore diameters of the AAO inserts. The original 50-nm pore diameter of AAO was adjusted by depositing films of thickness 5, 10, and 15 nm on AAO. Bis(tert-butylimido)-bis(dimethylamido)molybdenum and ammonia were used as precursors in deposition. The resulting pore diameters in the nitride-coated AAO inserts were 40, 30, and 20 nm, respectively. Injection molding of PP was conducted with the coated inserts, as well as with the non-coated insert. Besides the pore diameter, the injection mold temperature was varied with temperatures of 50, 70, and 90 degrees C tested. Water contact angles of PP casts were measured and compared with theoretical contact angles calculated from Wenzel and Cassie-Baxter theories. The highest contact angle, 140 degrees , was observed for PP molded with the AAO mold insert with 30-nm pore diameter. The Cassie-Baxter theory showed better fit than the Wenzel theory to the experimental values. With the optimal AAO mask, the nanofeatures in the molded PP pieces were 100 nm high. In explanation of this finding, it is suggested that some sticking and stretching of the nanofeatures occurs during the molding. Increase in the mold temperature increased the contact angle.

  15. On the growth of conductive aluminum doped zinc oxide on 001 strontium titanate single crystals

    NASA Astrophysics Data System (ADS)

    Trinca, L. M.; Galca, A. C.; Aldica, G.; Radu, R.; Mercioniu, I.; Pintilie, L.

    2016-02-01

    Aluminum doped zinc oxide (AZO) thin films were obtained by pulsed laser deposition on (001) SrTiO3 (STO) on a range of substrate temperatures during ablation between 300 °C and 600 °C. A hexagonal system lying on a cubic one should be difficult to be obtained in epitaxial form. The geometrical selection of the AZO growth on (001) STO is not giving a unique preferential orientation. Two orientations, c-axis (along [001]) and 110, have been observed experimentally with different ratios at different substrate temperature. Discussions are made with respect to the temperature dependence of lattice mismatch between the two cases and the cubic surface of the substrate, and to the substrate surface morphology and terminating atomic layer composition. The 110 AZO is the main phase at deposition temperature of 550 °C, while for other substrate temperatures the 001 is the preferential orientation. The conductive character of 110 AZO thin film have been inferred from both ellipsometry spectra and current-voltage measurements. Excepting the samples deposited at 300 °C, the lowest resistivity is recorded for the samples with 110 AZO as the main phase.

  16. Sprayed lanthanum doped zinc oxide thin films

    NASA Astrophysics Data System (ADS)

    Bouznit, Y.; Beggah, Y.; Ynineb, F.

    2012-01-01

    Lanthanum doped zinc oxide thin films were deposited on soda-lime glass substrates using a pneumatic spray pyrolysis technique. The films were prepared using different lanthanum concentrations at optimum deposition parameters. We studied the variations in structural, morphological and optical properties of the samples due to the change of doping concentration in precursor solutions. X-ray diffraction (XRD) patterns show that pure and La-doped ZnO thin films are highly textured along c-axis perpendicular to the surface of the substrate. Scanning electron micrographs show that surface morphology of ZnO films undergoes a significant change according to lanthanum doping. All films exhibit a transmittance higher than 80% in the visible region.

  17. Graphene oxide film as solid lubricant.

    PubMed

    Liang, Hongyu; Bu, Yongfeng; Zhang, Junyan; Cao, Zhongyue; Liang, Aimin

    2013-07-10

    As a layered material, graphene oxide (GO) film is a good candidate for improving friction and antiwear performance of silicon-based MEMS devices. Via a green electrophoretic deposition (EPD) approach, GO films with tunable thickness in nanoscale are fabricated onto silicon wafer in a water solution. The morphology, microstructure, and mechanical properties as well as the friction coefficient and wear resistance of the films were investigated. The results indicated that the friction coefficient of silicon wafer was reduced to 1/6 its value, and the wear volume was reduced to 1/24 when using GO film as solid lubricant. These distinguished tribology performances suggest that GO films are expected to be good solid lubricants for silicon-based MEMS/NEMS devices.

  18. Transferable graphene oxide films with tunable microstructures.

    PubMed

    Hasan, Saad A; Rigueur, John L; Harl, Robert R; Krejci, Alex J; Gonzalo-Juan, Isabel; Rogers, Bridget R; Dickerson, James H

    2010-12-28

    This report describes methods to produce large-area films of graphene oxide from aqueous suspensions using electrophoretic deposition. By selecting the appropriate suspension pH and deposition voltage, films of the negatively charged graphene oxide sheets can be produced with either a smooth "rug" microstructure on the anode or a porous "brick" microstructure on the cathode. Cathodic deposition occurs in the low pH suspension with the application of a relatively high voltage, which facilitates a gradual change in the colloids' charge from negative to positive as they adsorb protons released by the electrolysis of water. The shift in the colloids' charge also gives rise to the brick microstructure, as the concurrent decrease in electrostatic repulsion between graphene oxide sheets results in the formation of multilayered aggregates (the "bricks"). Measurements of water contact angle revealed the brick films (79°) to be more hydrophobic than the rug films (41°), a difference we attribute primarily to the distinct microstructures. Finally, we describe a sacrificial layer technique to make these graphene oxide films free-standing, which would enable them to be placed on arbitrary substrates.

  19. Oxidation resistance of aluminum-coated Fe-20Cr alloys containing rare earths or yttrium

    SciTech Connect

    Sigler, D.R. )

    1993-10-01

    Aluminum-coated Fe-20Cr (rare earth or yttrium) alloy foils were developed with oxidation resistance equivalent or superior to Fe-20Cr-5Al (rare earth or yttrium) alloy foils. The coated foils were made by dipping Fe-20Cr sheet into a salt-covered aluminum bath and then rolling the sheet to foil. Oxidation resistance of the coated foil was enhanced by adding rare earths or yttrium to the Fe-20Cr substrate alloys to insure oxide adherence. Test results indicate that only sufficient addition to tie up sulfur as a stable sulfide is needed in the Fe-20Cr alloy. Aluminum-coated foils show lower oxide growth rates than similar Fe-Cr-Al alloys, most likely the result of fewer impurities (particularly Fe) is the coated foils' growing oxide scale. 31 refs., 18 figs., 2 tabs.

  20. Photolytic deposition of aluminum nitride and oxy-nitride films at temperatures ≤ 350k

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, Gouri; Lince, Jeffrey R.

    1996-01-01

    Aluminum nitride and oxy-nitride thin films have been deposited on Si(100) substrates at temperatures of 300-350K by gas-phase excimer laser photolysis at 193 nm. The precursors used for this deposition process are trimethylamine alane and ammonia. The properties of these laser-deposited films were studied using scanning electron microscopy, energy dispersive x-ray analysis, and x-ray diffraction. X-ray photoelectron spectroscopy has been extensively used to provide information regarding the chemical compositions on the surface and in the bulk of these laser deposited films, as well as on the chemical states of the components of the films. Well-adhering, smooth, amorphous films of AlN are obtained at a substrate temperature of 350K using this technique.

  1. Nanotribological properties of alkanephosphonic acid self-assembled monolayers on aluminum oxide: effects of fluorination and substrate crystallinity.

    PubMed

    Brukman, Matthew J; Oncins Marco, Gerard; Dunbar, Timothy D; Boardman, Larry D; Carpick, Robert W

    2006-04-25

    Two phosphonic acid (PA) self-assembled monolayers (SAMs) are studied on three aluminum oxide surfaces: the C and R crystallographic planes of single crystal alpha-alumina (sapphire) and an amorphous vapor-deposited alumina thin film. SAMs are either fully hydrogenated CH3(CH2)17PO3H2 or semifluorinated CF3(CF2)7(CH2)11PO3H2. Atomic force microscope (AFM) topographic imaging reveals that the deposited films are homogeneous, atomically smooth, and stable for months in the laboratory environment. Static and advancing contact angle measurements agree with previous work on identical or similar films, but receding measurements suggest reduced coverage here. To enable reproducible nanotribology measurements with the AFM, a scanning protocol is developed that leads to a stable configuration of the silicon tip. Adhesion for the semifluorinated films is either comparable to or lower than that for the hydrogenated films, with a dependence on contact history observed. Friction between each film and the tips depends strongly upon the type of molecule, with the fluorinated species exhibiting substantially higher friction. Subtle but reproducible differences in friction are observed for a given SAM depending on the substrate, revealing differences in packing density for the SAMs on the different substrates. Friction is seen to increase linearly with load, a consequence of the tip's penetration into the monolayer.

  2. Cell Adhesion and Growth on the Anodized Aluminum Oxide Membrane.

    PubMed

    Park, Jeong Su; Moon, Dalnim; Kim, Jin-Seok; Lee, Jin Seok

    2016-03-01

    Nanotopological cues are popular tools for in vivo investigation of the extracellular matrix (ECM) and cellular microenvironments. The ECM is composed of multiple components and generates a complex microenvironment. The development of accurate in vivo methods for the investigation of ECM are important for disease diagnosis and therapy, as well as for studies on cell behavior. Here, we fabricated anodized aluminum oxide (AAO) membranes using sulfuric and oxalic acid under controlled voltage and temperature. The membranes were designed to possess three different pore and interpore sizes, AAO-1, AAO-2, and AAO-3 membranes, respectively. These membranes were used as tools to investigate nanotopology-signal induced cell behavior. Cancerous cells, specifically, the OVCAR-8 cell-line, were cultured on porous AAO membranes and the effects of these membranes on cell shape, proliferation, and viability were studied. AAO-1 membranes bearing small sized pores were found to maintain the spreading shape of the cultured cells. Cells cultured on AAO-2 and AAO-3 membranes, bearing large pore-sized AAO membranes, changed shape from spreading to rounding. Furthermore, cellular area decreased when cells were cultured on all three AAO membranes that confirmed decreased levels of focal adhesion kinase (FAK). Additionally, OVCAR-8 cells exhibited increased proliferation on AAO membranes possessing various pore sizes, indicating the importance of the nanosurface structure in regulating cell behaviors, such as cell proliferation. Our results suggest that porous-AAO membranes induced nanosurface regulated cell behavior as focal adhesion altered the intracellular organization of the cytoskeleton. Our results may find potential applications as tools in in vivo cancer research studies.

  3. Aluminum-Doped Zinc Oxide as Highly Stable Electron Collection Layer for Perovskite Solar Cells.

    PubMed

    Zhao, Xingyue; Shen, Heping; Zhang, Ye; Li, Xin; Zhao, Xiaochong; Tai, Meiqian; Li, Jingfeng; Li, Jianbao; Li, Xin; Lin, Hong

    2016-03-01

    Although low-temperature, solution-processed zinc oxide (ZnO) has been widely adopted as the electron collection layer (ECL) in perovskite solar cells (PSCs) because of its simple synthesis and excellent electrical properties such as high charge mobility, the thermal stability of the perovskite films deposited atop ZnO layer remains as a major issue. Herein, we addressed this problem by employing aluminum-doped zinc oxide (AZO) as the ECL and obtained extraordinarily thermally stable perovskite layers. The improvement of the thermal stability was ascribed to diminish of the Lewis acid-base chemical reaction between perovskite and ECL. Notably, the outstanding transmittance and conductivity also render AZO layer as an ideal candidate for transparent conductive electrodes, which enables a simplified cell structure featuring glass/AZO/perovskite/Spiro-OMeTAD/Au. Optimization of the perovskite layer leads to an excellent and repeatable photovoltaic performance, with the champion cell exhibiting an open-circuit voltage (Voc) of 0.94 V, a short-circuit current (Jsc) of 20.2 mA cm(-2), a fill factor (FF) of 0.67, and an overall power conversion efficiency (PCE) of 12.6% under standard 1 sun illumination. It was also revealed by steady-state and time-resolved photoluminescence that the AZO/perovskite interface resulted in less quenching than that between perovskite and hole transport material.

  4. A colorimetric sensor based on anodized aluminum oxide (AAO) substrate for the detection of nitroaromatics.

    SciTech Connect

    Liu, Y.; Wang, H. H.; Indacochea, J. E.; Wang, M. L.

    2011-12-15

    Simple and low cost colorimetric sensors for explosives detection were explored and developed. Anodized aluminum oxide (AAO) with large surface area through its porous structure and light background color was utilized as the substrate for colorimetric sensors. Fabricated thin AAO films with thickness less than {approx} 500 nm allowed us to observe interference colors which were used as the background color for colorimetric detection. AAO thin films with various thickness and pore-to-pore distance were prepared through anodizing aluminum foils at different voltages and times in dilute sulfuric acid. Various interference colors were observed on these samples due to their difference in structures. Accordingly, suitable anodization conditions that produce AAO samples with desired light background colors for optical applications were obtained. Thin film interference model was applied to analyze the UV-vis reflectance spectra and to estimate the thickness of the AAO membranes. We found that the thickness of produced AAO films increased linearly with anodization time in sulfuric acid. In addition, the growth rate was higher for AAO anodized using higher voltages. The thin film interference formulism was further validated with a well established layer by layer deposition technique. Coating poly(styrene sulfonate) sodium salt (PSS) and poly(allylamine hydrochloride) (PAH) layer by layer on AAO thin film consistently shifted its surface color toward red due to the increase in thickness. The red shift of UV-vis reflectance was correlated quantitatively to the number of layers been assembled. This sensitive red shift due to molecular attachment (increase in thickness) on AAO substrate was applied toward nitroaromatics detection. Aminopropyltrimethoxysilane (APTS) which can be attached onto AAO nanowells covalently through silanization and attract TNT molecules was coated and applied for TNT detection. UV-vis spectra of AAO with APTS shifted to the longer wavelength side due to

  5. THIN FILMS FORMED BY ELECTROCHEMICAL REACTIONS

    DTIC Science & Technology

    ELECTROCHEMISTRY, * THIN FILMS (STORAGE DEVICES), ALUMINUM, ANODES (ELECTROLYTIC CELL), CAPACITORS, CIRCUITS, MICROMETERS, NIOBIUM, OXIDATION, RESISTORS, TANTALUM, TITANIUM, TUNGSTEN, VACUUM APPARATUS, ZIRCONIUM

  6. High quality transparent conducting oxide thin films

    DOEpatents

    Gessert, Timothy A.; Duenow, Joel N.; Barnes, Teresa; Coutts, Timothy J.

    2012-08-28

    A transparent conducting oxide (TCO) film comprising: a TCO layer, and dopants selected from the elements consisting of Vanadium, Molybdenum, Tantalum, Niobium, Antimony, Titanium, Zirconium, and Hafnium, wherein the elements are n-type dopants; and wherein the transparent conducting oxide is characterized by an improved electron mobility of about 42 cm.sup.2/V-sec while simultaneously maintaining a high carrier density of .about.4.4e.times.10.sup.20 cm.sup.-3.

  7. Silicon and aluminum doping effects on the microstructure and properties of polymeric amorphous carbon films

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoqiang; Hao, Junying; Xie, Yuntao

    2016-08-01

    Polymeric amorphous carbon films were prepared by radio frequency (R.F. 13.56 MHz) magnetron sputtering deposition. The microstructure evolution of the deposited polymeric films induced by silicon (Si) and aluminum(Al) doping were scrutinized through infrared spectroscopy, multi-wavelength Raman spectroscopy, scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The comparative results show that Si doping can enhance polymerization and Al doping results in an increase in the ordered carbon clusters. Si and Al co-doping into polymeric films leads to the formation of an unusual dual nanostructure consisting of cross-linked polymer-like hydrocarbon chains and fullerene-like carbon clusters. The super-high elasticity and super-low friction coefficients (<0.002) under a high vacuum were obtained through Si and Al co-doping into the films. Unconventionally, the co-doped polymeric films exhibited a superior wear resistance even though they were very soft. The relationship between the microstructure and properties of the polymeric amorphous carbon films with different elements doping are also discussed in detail.

  8. Aluminum thin film enhanced IR nanosecond laser-induced frontside etching of transparent materials

    NASA Astrophysics Data System (ADS)

    Nieto, Daniel; Cambronero, Ferran; Flores-Arias, María Teresa; Farid, Nazar; O'Connor, Gerard M.

    2017-01-01

    Laser processing of glass is of significant commercial interest for microfabrication of precision optical engineering devices. In this work, a laser ablation enhancement mechanism for microstructuring of glass materials is presented. The method consists of depositing a thin film of aluminum on the front surface of the glass material to be etched. The laser beam modifies the glass material by being incident on this front-side. The influence of ablation fluence in the nanosecond regime, in combination with the deposition of the aluminum layer of various thicknesses, is investigated by determining the ablation threshold for different glass materials including soda-lime, borosilicate, fused silica and sapphire. Experiments are performed using single laser pulse per shot in an air environment. The best enhancement in terms of threshold fluence reduction is obtained for a 16 nm thick aluminum layer where a reduction of two orders of magnitude in the ablation threshold fluence is observed for all the glass samples investigated in this work.

  9. Self-assembly formation of lipid bilayer coatings on bare aluminum oxide: overcoming the force of interfacial water.

    PubMed

    Jackman, Joshua A; Tabaei, Seyed R; Zhao, Zhilei; Yorulmaz, Saziye; Cho, Nam-Joon

    2015-01-14

    Widely used in catalysis and biosensing applications, aluminum oxide has become popular for surface functionalization with biological macromolecules, including lipid bilayer coatings. However, it is difficult to form supported lipid bilayers on aluminum oxide, and current methods require covalent surface modification, which masks the interfacial properties of aluminum oxide, and/or complex fabrication techniques with specific conditions. Herein, we addressed this issue by identifying simple and robust strategies to form fluidic lipid bilayers on aluminum oxide. The fabrication of a single lipid bilayer coating was achieved by two methods, vesicle fusion under acidic conditions and solvent-assisted lipid bilayer (SALB) formation under near-physiological pH conditions. Importantly, quartz crystal microbalance with dissipation (QCM-D) monitoring measurements determined that the hydration layer of a supported lipid bilayer on aluminum oxide is appreciably thicker than that of a bilayer on silicon oxide. Fluorescence recovery after photobleaching (FRAP) analysis indicated that the diffusion coefficient of lateral lipid mobility was up to 3-fold greater on silicon oxide than on aluminum oxide. In spite of this hydrodynamic coupling, the diffusion coefficient on aluminum oxide, but not silicon oxide, was sensitive to the ionic strength condition. Extended-DLVO model calculations estimated the thermodynamics of lipid-substrate interactions on aluminum oxide and silicon oxide, and predict that the range of the repulsive hydration force is greater on aluminum oxide, which in turn leads to an increased equilibrium separation distance. Hence, while a strong hydration force likely contributes to the difficulty of bilayer fabrication on aluminum oxide, it also confers advantages by stabilizing lipid bilayers with thicker hydration layers due to confined interfacial water. Such knowledge provides the basis for improved surface functionalization strategies on aluminum oxide

  10. PLASMA POLYMER FILMS AS ADHESION PROMOTING PRIMERS FOR ALUMINUM. PART II: STRENGTH AND DURABILITY OF LAP JOINTS

    EPA Science Inventory

    Plasma polymerized hexamethyldisiloxane (HMDSO) films (~800 A in thickness) were deposited onto 6111-T4 aluminum substrates in radio frequency and microwave powered reactors and used as primers for structural adhesive bonding. Processing variables such as substrate pre-treatment,...

  11. Patterning of Indium Tin Oxide Films

    NASA Technical Reports Server (NTRS)

    Immer, Christopher

    2008-01-01

    A relatively rapid, economical process has been devised for patterning a thin film of indium tin oxide (ITO) that has been deposited on a polyester film. ITO is a transparent, electrically conductive substance made from a mixture of indium oxide and tin oxide that is commonly used in touch panels, liquid-crystal and plasma display devices, gas sensors, and solar photovoltaic panels. In a typical application, the ITO film must be patterned to form electrodes, current collectors, and the like. Heretofore it has been common practice to pattern an ITO film by means of either a laser ablation process or a photolithography/etching process. The laser ablation process includes the use of expensive equipment to precisely position and focus a laser. The photolithography/etching process is time-consuming. The present process is a variant of the direct toner process an inexpensive but often highly effective process for patterning conductors for printed circuits. Relative to a conventional photolithography/ etching process, this process is simpler, takes less time, and is less expensive. This process involves equipment that costs less than $500 (at 2005 prices) and enables patterning of an ITO film in a process time of less than about a half hour.

  12. Effect of oxide layer formation on deformation of aluminum alloys under fire conditions

    DOE PAGES

    Yilmaz, Nadir; Vigil, Francisco M.; Tolendino, Greg; ...

    2015-05-14

    The purpose of this study is to investigate the structural behavior of aluminum alloys used in the aerospace industry when exposed to conditions similar to those of an accident scenario, such as a fuel fire. This study focuses on the role that the aluminum oxide layer plays in the deformation and the strength of the alloy above melting temperature. To replicate some of the thermal and atmospheric conditions that the alloys might experience in an accident scenario, aluminum rod specimens were subjected to temperatures near to or above their melting temperature in air, nitrogen, and vacuum environments. The characteristics ofmore » their deformation, such as geometry and rate of deformation, were observed. Tests were conducted by suspending aluminum rods vertically from an enclosure. This type of experiment was performed in two different environments: air and nitrogen. The change in environments allowed the effects of the oxide layer on the material strength to be analyzed by inhibiting the growth of the oxide layer. Observations were reported from imaging taken during the experiment showing creep behavior of aluminum alloys at elevated temperatures and time to failure. In addition, an example of tensile load–displacement data obtained in air and vacuum was reported to understand the effect of oxide layer on aluminum deformation and strength.« less

  13. Effect of oxide layer formation on deformation of aluminum alloys under fire conditions

    SciTech Connect

    Yilmaz, Nadir; Vigil, Francisco M.; Tolendino, Greg; Gill, Walt; Donaldson, A. Burl

    2015-05-14

    The purpose of this study is to investigate the structural behavior of aluminum alloys used in the aerospace industry when exposed to conditions similar to those of an accident scenario, such as a fuel fire. This study focuses on the role that the aluminum oxide layer plays in the deformation and the strength of the alloy above melting temperature. To replicate some of the thermal and atmospheric conditions that the alloys might experience in an accident scenario, aluminum rod specimens were subjected to temperatures near to or above their melting temperature in air, nitrogen, and vacuum environments. The characteristics of their deformation, such as geometry and rate of deformation, were observed. Tests were conducted by suspending aluminum rods vertically from an enclosure. This type of experiment was performed in two different environments: air and nitrogen. The change in environments allowed the effects of the oxide layer on the material strength to be analyzed by inhibiting the growth of the oxide layer. Observations were reported from imaging taken during the experiment showing creep behavior of aluminum alloys at elevated temperatures and time to failure. In addition, an example of tensile load–displacement data obtained in air and vacuum was reported to understand the effect of oxide layer on aluminum deformation and strength.

  14. Thin-Film Solid Oxide Fuel Cells

    NASA Technical Reports Server (NTRS)

    Chen, Xin; Wu, Nai-Juan; Ignatiev, Alex

    2009-01-01

    The development of thin-film solid oxide fuel cells (TFSOFCs) and a method of fabricating them have progressed to the prototype stage. This can result in the reduction of mass, volume, and the cost of materials for a given power level.

  15. Metal current collect protected by oxide film

    DOEpatents

    Jacobson, Craig P.; Visco, Steven J.; DeJonghe, Lutgard C.

    2004-05-25

    Provided are low-cost, mechanically strong, highly electronically conductive current collects and associated structures for solid-state electrochemical devices, techniques for forming these structures, and devices incorporating the structures. The invention provides solid state electrochemical devices having as current interconnects a ferritic steel felt or screen coated with a protective oxide film.

  16. Study on the fabrication of back surface reflectors in nano-crystalline silicon thin-film solar cells by using random texturing aluminum anodization

    NASA Astrophysics Data System (ADS)

    Shin, Kang Sik; Jang, Eunseok; Cho, Jun-Sik; Yoo, Jinsu; Park, Joo Hyung; Byungsung, O.

    2015-09-01

    In recent decades, researchers have improved the efficiency of amorphous silicon solar cells in many ways. One of the easiest and most practical methods to improve solar-cell efficiency is adopting a back surface reflector (BSR) as the bottom layer or as the substrate. The BSR reflects the incident light back to the absorber layer in a solar cell, thus elongating the light path and causing the so-called "light trapping effect". The elongation of the light path in certain wavelength ranges can be enhanced with the proper scale of BSR surface structure or morphology. An aluminum substrate with a surface modified by aluminum anodizing is used to improve the optical properties for applications in amorphous silicon solar cells as a BSR in this research due to the high reflectivity and the low material cost. The solar cells with a BSR were formed and analyzed by using the following procedures: First, the surface of the aluminum substrate was degreased by using acetone, ethanol and distilled water, and it was chemically polished in a dilute alkali solution. After the cleaning process, the aluminum surface's morphology was modified by using a controlled anodization in a dilute acid solution to form oxide on the surface. The oxidized film was etched off by using an alkali solution to leave an aluminum surface with randomly-ordered dimple-patterns of approximately one micrometer in size. The anodizing conditions and the anodized aluminum surfaces after the oxide layer had been removed were systematically investigated according to the applied voltage. Finally, amorphous silicon solar cells were deposited on a modified aluminum plate by using dc magnetron sputtering. The surfaces of the anodized aluminum were observed by using field-emission scanning electron microscopy. The total and the diffuse reflectances of the surface-modified aluminum sheets were measured by using UV spectroscopy. We observed that the diffuse reflectances increased with increasing anodizing voltage. The

  17. Semitransparent polymer-based solar cells with aluminum-doped zinc oxide electrodes.

    PubMed

    Wilken, Sebastian; Wilkens, Verena; Scheunemann, Dorothea; Nowak, Regina-Elisabeth; von Maydell, Karsten; Parisi, Jürgen; Borchert, Holger

    2015-01-14

    With the use of two transparent electrodes, organic polymer-fullerene solar cells are semitransparent and may be combined to parallel-connected multijunction devices or used for innovative applications like power-generating windows. A challenging issue is the optimization of the electrodes, to combine high transparency with adequate electric properties. In the present work, we study the potential of sputter-deposited aluminum-doped zinc oxide as an alternative to the widely used but relatively expensive indium tin oxide (ITO) as cathode material in semitransparent polymer-fullerene solar cells. Concerning the anode, we utilized an insulator-metal-insulator structure based on ultrathin Au films embedded between two evaporated MoO3 layers, with the outer MoO3 film (capping layer) serving as a light coupling layer. The performance of the ITO-free semitransparent polymer-fullerene solar cells was systematically studied as dependent on the thickness of the capping layer and the active layer as well as the illumination direction. These variations were found to have strong impact on the obtained photocurrent densities. We performed optical simulations of the electric field distribution within the devices using the transfer-matrix method, to analyze the origin of the current density variations in detail and provide deep insight into the device physics. With the conventional absorber materials studied here, optimized ITO-free and semitransparent devices reached 2.0% power conversion efficiency and a maximum optical transmission of 60%, with the device concept being potentially transferable to other absorber materials.

  18. Synthesis of epitaxial Si(100) nanowires on Si(100) substrate using vapor liquid solid growth in anodic aluminum oxide nanopore arrays

    NASA Astrophysics Data System (ADS)

    Shimizu, T.; Senz, S.; Shingubara, S.; Gösele, U.

    2007-06-01

    The synthesis of epitaxial Si nanowires with growth direction parallel to Si [100] on Si(100) substrate was demonstrated using a combination of anodic aluminum oxide (AAO) template, catalytic gold film sandwiched between the template and the Si(100) substrate and vapor-liquid-solid growth using SiH4 as the Si source. After growing out from the AAO nanopores, most Si nanowires changed their diameter and growth direction into larger diameter and <111> direction.

  19. Microtensile testing and cyclic deformation of freestanding aluminum thin films

    NASA Astrophysics Data System (ADS)

    Barbosa, Nicholas, III

    2005-07-01

    Although the fatigue properties of bulk materials are well characterized for most materials, the implications of reducing the size scale of cyclically strained members to thicknesses on the order of single grains are not well defined. In this work, the cyclic deformation properties of 1 mum Al thin films are investigated. The fatigue test structures, the uniaxial load frame, the associated electronics, and the data acquisition and control software were all custom designed and fabricated in order to evaluate the monotonic and cyclic properties of thin metallic films. Test structures are 600 mum long x 100 mum wide x 1 mum thick. Monotonic tests were performed at a displacement rate of 5 mum/s and samples were pulled to failure. A value for the Young's modulus of the Al beams was determined to be 63.0 GPa +/- 5.1 GPa. The 0.2% yield stress was found to be 314.3 MPa +/- 45.2 MPa, the ultimate tensile strength was found to be 347.1 MPa +/- 56.3 MPa, and the average elongation was found to be 1.3% +/- 0.5%. Monotonic failures occurred through an oblique fracture. Fatigue tests were performed on the test structures under total strain amplitude control. Samples were fatigue under tension-tension conditions with strain amplitudes from 0.08% to 0.34%. The Al thin films were found to follow a Coffin-Manson relationship with a fatigue ductility coefficient of 0.022 and a fatigue ductility exponent of -0.278. Film fatigue fracture surfaces were similar in nature to bulk tension-tension fatigue, with the presence of slip offsets. The behavior of the 1 mum Al freestanding films, both in the monotonic and fatigue testing, was very similar to the fatigue properties of bulk materials when the significantly smaller sample grain size was considered.

  20. Amorphous alumina thin films deposited on titanium: Interfacial chemistry and thermal oxidation barrier properties

    SciTech Connect

    Baggetto, Loic; Charvillat, Cedric; Thebault, Yannick; Esvan, Jerome; Lafont, Marie-Christine; Scheid, Emmanuel; Veith, Gabriel M.; Vahlas, Constantin

    2015-12-02

    Ti/Al2O3 bilayer stacks are used as model systems to investigate the role of atomic layer deposition (ALD) and chemical vapor deposition (CVD) to prepare 30-180 nm thick amorphous alumina films as protective barriers for the medium temperature oxidation (500-600⁰C) of titanium, which is employed in aeronautic applications. X-ray diffraction (XRD), transmission electron microscopy (TEM) with selected area electron diffraction (SAED), and X-ray photoelectron spectroscopy (XPS) results show that the films produced from the direct liquid injection (DLI) CVD of aluminum tri-isopropoxide (ATI) are poor oxygen barriers. The films processed using the ALD of trimethylaluminum (TMA) show good barrier properties but an extensive intermixing with Ti which subsequently oxidizes. In contrast, the films prepared from dimethyl aluminum isopropoxide (DMAI) by CVD are excellent oxygen barriers and show little intermixing with Ti. Overall, these measurements correlate the effect of the alumina coating thickness, morphology, and stoichiometry resulting from the preparation method to the oxidation barrier properties, and show that compact and stoichiometric amorphous alumina films offer superior barrier properties.

  1. Amorphous alumina thin films deposited on titanium: Interfacial chemistry and thermal oxidation barrier properties

    DOE PAGES

    Baggetto, Loic; Charvillat, Cedric; Thebault, Yannick; ...

    2015-12-02

    Ti/Al2O3 bilayer stacks are used as model systems to investigate the role of atomic layer deposition (ALD) and chemical vapor deposition (CVD) to prepare 30-180 nm thick amorphous alumina films as protective barriers for the medium temperature oxidation (500-600⁰C) of titanium, which is employed in aeronautic applications. X-ray diffraction (XRD), transmission electron microscopy (TEM) with selected area electron diffraction (SAED), and X-ray photoelectron spectroscopy (XPS) results show that the films produced from the direct liquid injection (DLI) CVD of aluminum tri-isopropoxide (ATI) are poor oxygen barriers. The films processed using the ALD of trimethylaluminum (TMA) show good barrier properties butmore » an extensive intermixing with Ti which subsequently oxidizes. In contrast, the films prepared from dimethyl aluminum isopropoxide (DMAI) by CVD are excellent oxygen barriers and show little intermixing with Ti. Overall, these measurements correlate the effect of the alumina coating thickness, morphology, and stoichiometry resulting from the preparation method to the oxidation barrier properties, and show that compact and stoichiometric amorphous alumina films offer superior barrier properties.« less

  2. Large-scale fabrication of 2-D nanoporous graphene using a thin anodic aluminum oxide etching mask.

    PubMed

    Lee, Jae-Hyun; Jang, Yamujin; Heo, Keun; Lee, Jeong-Mi; Choi, Soon Hyung; Joo, Won-Jae; Hwang, Sung Woo; Whang, Dongmok

    2013-11-01

    A large-scale nanoporous graphene (NPG) fabrication method via a thin anodic aluminum oxide (AAO) etching mask is presented in this paper. A thin AAO film is successfully transferred onto a hydrophobic graphene surface under no external force. The AAO film is completely stacked on the graphene due to the van der Waals force. The neck width of the NPG can be controlled ranging from 10 nm to 30 nm with different AAO pore widening times. Extension of the NPG structure is demonstrated on a centimeter scale up to 2 cm2. AAO and NPG structures are characterized using optical microscopy (OM), Raman spectroscopy and field-emission scanning electron microscopy (FE-SEM). A field effect transistor (FET) is realized by using NPG. Its electrical characteristics turn out to be different from that of pristine graphene, which is due to the periodic nanostructures. The proposed fabrication method could be adapted to a future graphene-based nano device.

  3. Dealloying of Platinum-Aluminum Thin Films: Dynamics of Pattern Formation

    NASA Astrophysics Data System (ADS)

    Galinski, Henning; Ryll, Thomas; Schlagenhauf, Lukas; Rechberger, Felix; Ying, Sun; Gauckler, Ludwig J.; Mornaghini, Flavio C. F.; Ries, Yasmina; Spolenak, Ralph; Döbeli, Max

    2011-11-01

    The application of focused ion beam (FIB) nanotomography and Rutherford backscattering spectroscopy (RBS) to dealloyed platinum-aluminum thin films allows for an in-depth analysis of the dominating physical mechanisms of nanoporosity formation during the dealloying process. The porosity formation due to the dissolution of the less noble aluminum in the alloy is treated as result of a reaction-diffusion system. The RBS and FIB analysis yields that the porosity evolution has to be regarded as superposition of two independent processes, a linearly propagating diffusion front with a uniform speed and a slower dissolution process in regions which have already been passed by the diffusion front. The experimentally observed front evolution is captured by the Fisher-Kolmogorov-Petrovskii-Piskounov (FKPP). The slower dissolution is represented by a zero-order rate law which causes a gradual porosity in the thin film.

  4. Aluminum and copper in drinking water enhance inflammatory or oxidative events specifically in the brain.

    PubMed

    Becaria, Angelica; Lahiri, Debomoy K; Bondy, Stephen C; Chen, DeMao; Hamadeh, Ali; Li, Huihui; Taylor, Russell; Campbell, Arezoo

    2006-07-01

    Inflammatory and oxidative events are up-regulated in the brain of AD patients. It has been reported that in animal models of AD, exposure to aluminum (Al) or copper (Cu) enhanced oxidative events and accumulation of amyloid beta (Abeta) peptides. The present study was designed to evaluate the effect of a 3-month exposure of mice to copper sulfate (8 microM), aluminum lactate (10 or 100 microM), or a combination of the salts. Results suggest that although Al or Cu may independently initiate inflammatory or oxidative events, they may function cooperatively to increase APP levels.

  5. Niobium-aluminum base alloys having improved, high temperature oxidation resistance

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G. (Inventor); Stephens, Joseph R. (Inventor)

    1991-01-01

    A niobium-aluminum base alloy having improved oxidation resistance at high temperatures and consisting essentially of 48%-52% niobium, 36%-42% aluminum, 4%-10% chromium, 0%-2%, more preferably 1%-2%, silicon and/or tungsten with tungsten being preferred, and 0.1%-2.0% of a rare earth selected from the group consisting of yttrium, ytterbium and erbium. Parabolic oxidation rates, k.sub.p, at 1200.degree. C. range from about 0.006 to 0.032 (mg/cm.sup.2).sup.2 /hr. The new alloys also exhibit excellent cyclic oxidation resistance.

  6. Pulsed DC magnetron sputtered piezoelectric thin film aluminum nitride – Technology and piezoelectric properties

    SciTech Connect

    Stoeckel, C. Kaufmann, C.; Hahn, R.; Schulze, R.; Billep, D.; Gessner, T.

    2014-07-21

    Pulsed DC magnetron sputtered aluminum nitride (AlN) thin films are prepared on several seed layers and at different sputtering conditions. The piezoelectric c-axis (002) orientation of the AlN is analyzed with X-ray diffraction method. The transverse piezoelectric coefficient d{sub 31} is determined with a Laser-Doppler-Vibrometer at cantilevers and membranes by analytical calculations and finite element method. Additionally, thin film AlN on bulk silicon is used to characterize the longitudinal piezoelectric charge coefficient d{sub 33}.

  7. Pulsed photothermal reflectance measurement of the thermal conductivity of sputtered aluminum nitride thin films

    SciTech Connect

    Zhao Yimin; Zhu Chunlin; Wang Sigen; Tian, J.Z.; Yang, D.J.; Chen, C.K.; Cheng Hao; Hing, Peter

    2004-10-15

    We report on measurements of the thermal conductivity of reactively sputtered aluminum nitride (AlN) thin films with different thickness, ranging from 100 nm to 1 {mu}m, on silicon substrates. The measurements were made at room temperature using the pulsed photothermal reflectance technique. The thermal conductivities of the sample are found to be significantly lower than the single-crystal bulk AlN and increase with an increasing thickness. The thermal resistance at the interface between the AlN film and the silicon substrate is found to be about 7-8x10{sup -8} m{sup 2} K/W.

  8. Luminescent down shifting effect of Ce-doped yttrium aluminum garnet thin films on solar cells

    SciTech Connect

    Shao, Guojian; Lou, Chaogang; Kang, Jian; Zhang, Hao

    2015-12-21

    Ce-doped yttrium aluminum garnet (YAG:Ce) thin films as luminescent down shifting (LDS) materials are introduced into the module of crystalline silicon solar cells. The films are deposited by RF magnetron sputtering on the lower surface of the quartz glass. They convert ultraviolet and blue light into yellow light. Experiments show that the introduction of YAG:Ce films improves the conversion efficiency from 18.45% of the cells to 19.27% of the module. The increasing efficiency is attributed to LDS effect of YAG:Ce films and the reduced reflection of short wavelength photons. Two intentionally selected samples with similar reflectivities are used to evaluate roughly the effect of LDS alone on the solar cells, which leads to a relative increase by 2.68% in the conversion efficiency.

  9. Integration of piezoelectric aluminum nitride and ultrananocrystalline diamond films for implantable biomedical microelectromechanical devices

    NASA Astrophysics Data System (ADS)

    Zalazar, M.; Gurman, P.; Park, J.; Kim, D.; Hong, S.; Stan, L.; Divan, R.; Czaplewski, D.; Auciello, O.

    2013-03-01

    The physics for integration of piezoelectric aluminum nitride (AlN) films with underlying insulating ultrananocrystalline diamond (UNCD), and electrically conductive grain boundary nitrogen-incorporated UNCD (N-UNCD) and boron-doped UNCD (B-UNCD) layers, as membranes for microelectromechanical system implantable drug delivery devices, has been investigated. AlN films deposited on platinum layers on as grown UNCD or N-UNCD layer (5-10 nm rms roughness) required thickness of ˜400 nm to induce (002) AlN orientation with piezoelectric d33 coefficient ˜1.91 pm/V at ˜10 V. Chemical mechanical polished B-UNCD films (0.2 nm rms roughness) substrates enabled (002) AlN film 200 nm thick, yielding d33 = 5.3 pm/V.

  10. Edge Effects on Growth of Ordered Stress Relief Patterns in Free Sustained Aluminum Films

    NASA Astrophysics Data System (ADS)

    Yu, Sen-Jiang; Zhang, Yong-Ju; Chen, Miao-Gen

    2010-06-01

    An unusual form of ordered stress relief patterns is observed in a nearly free sustained aluminum film system deposited on liquid substrates by the thermal evaporation method. The edge effects on the growth of the ordered patterns are systematically studied. It is found that the patterns initiate from the film edges, preexisting ordered patterns, or other imperfections of the film. When the patterns extend in the film regions, they decay gradually and finally disappear. If they develop along the boundaries, however, the sizes are almost unchanged over several millimeters. The stress relief patterns look like rectangular waves in appearance, which are proven to evolve from sinusoidal to triangular waves gradually. The morphological evolution can be well explained by the general theory of buckling of plates.

  11. Anomalous hexagonal superstructure of aluminum oxide layer grown on NiAl(110) surface.

    PubMed

    Krukowski, Pawel; Chaunchaiyakul, Songpol; Minagawa, Yuto; Yajima, Nami; Akai-Kasaya, Megumi; Saito, Akira; Kuwahara, Yuji

    2016-11-11

    A modified method for the fabrication of a highly crystallized layer of aluminum oxide on a NiAl(110) surface is reported. The fabrication method involves the multistep selective oxidation of aluminum atoms on a NiAl(110) surface resulting from successive oxygen deposition and annealing. The surface morphology and local electronic structure of the novel aluminum oxide layer were investigated by high-resolution imaging using scanning tunneling microscopy (STM) and current imaging tunneling spectroscopy. In contrast to the standard fabrication method of aluminum oxide on a NiAl(110) surface, the proposed method produces an atomically flat surface exhibiting a hexagonal superstructure. The superstructure exhibits a slightly distorted hexagonal array of close-packed bright protrusions with a periodicity of 4.5 ± 0.2 nm. Atomically resolved STM imaging of the aluminum oxide layer reveals a hexagonal arrangement of dark contrast spots with a periodicity of 0.27 ± 0.02 nm. On the basis of the atomic structure of the fabricated layer, the formation of α-Al2O3(0001) on the NiAl(110) surface is suggested.

  12. Alginate-magnesium aluminum silicate films for buccal delivery of nicotine.

    PubMed

    Pongjanyakul, Thaned; Suksri, Hatairat

    2009-11-01

    Sodium alginate-magnesium aluminum silicate (SA-MAS) dispersions with nicotine (NCT) were prepared at different pHs and characterized for the particle size and zeta potential, NCT adsorbed by MAS, and flow behavior before film casting. The physicochemical properties, NCT content, in vitro bioadhesive property, and NCT release and permeation of the NCT-loaded SA-MAS films were investigated. This study showed that incorporation of NCT into the SA-MAS dispersions caused a change in particle size and flow behavior and that NCT could be adsorbed by MAS. The formation of protonated NCT at acidic and neutral pHs could interact with negatively charged MAS via an electrostatic force, resulting in the formation of NCT-MAS flocculates/complexes that could act as microreservoirs in the films. The NCT-loaded SA-MAS films prepared at pH 5 yielded the highest NCT content due to non-significant loss of NCT during drying. Moreover, pH of the preparation also affected the crystallinity and thermal properties of the films. The NCT release and permeation across the mucosal membrane of the films could be described using a matrix diffusion controlled mechanism. In addition, the NCT-loaded SA-MAS films also possessed a bioadhesive property for adhesion to the mucosal membrane. This finding suggests that the NCT-loaded SA-MAS films composed of numerous NCT-MAS complexes as microreservoirs demonstrated a strong potential for use as a buccal delivery system.

  13. Structural and Mechanical Characteristics of Anodic Oxide Films on Titanium

    SciTech Connect

    Pang, Mengzhi; Eakins, Daniel E; Norton, Murray G; Bahr, David F

    2001-01-01

    Oxide films were grown electrochemically on polycrystalline titanium in 0.1 M sulfuric acid (H2SO4) from open-circuit potential to a final potential of 9.4 V (vs silver-silver chloride [Ag-AgCl]) using three anodization rates: a step polarization, growth at 200 mV/s, and growth at 1 mV/s. Anodic polarization curves showed various degrees of oxygen evolution above 5.4 VAg-AgCl, indicating that the extent of oxide film breakdown depends on film growth rate, with slower growth rates undergoing more severe film breakdown. In-situ characterization of mechanical behavior of oxide films by nanoindentation revealed that the oxide film can sustain a tensile stress up to 2.5 GPa prior to film fracture. Among these three anodization rates, the oxide film formed by step polarization exhibited the highest film-strengthening effect. At applied potentials prior to oxide film breakdown, all films exhibited a strength of ≈1 GPa. The films ranged from amorphous titanium dioxide (TiO2) to anatase, with the extent of crystallization increasing with decreasing film growth rate. Correlations between electrochemical polarization, structural characteristics, and the mechanical behavior of these anodic films are discussed in relationship to electrostrictive stresses, which may lead to the breakdown of passive films. KEY WORDS: anodic polarization, films, nanoindentation, titanium, transmission electron microscopy.

  14. Volatile organic compound gas sensor based on aluminum-doped zinc oxide with nanoparticle.

    PubMed

    Choi, Nak-Jin; Lee, Hyung-Kun; Moon, Seung Eon; Yang, Woo Seok; Kim, Jongdae

    2013-08-01

    Thick film semiconductor gas sensors based on aluminum-doped zinc oxide (AZO) with nanoparticle size were fabricated to detect volatile organic compound (VOC) existed in building, especially, formaldehyde (HCHO) gas which was known as the cause of sick building syndrome. The sensing materials for screen printing were prepared using roll milling process with binder. The crystallite sizes of prepared materials were about 15 nm through X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). Gas response characteristics were examined for formaldehyde (HCHO), benzene, carbon monoxide, carbon dioxide gas existing in building. In particular, the sensors showed responses to HCHO gas at sub ppm as a function of operating temperatures and gas concentrations. Also, we investigated sensitivity, repeativity, selectivity, and response time of sensor. The transients were very sharp, taking less than 2 s for 90% response. The sensor has shown very stable response at 350 degrees C and followed a very good behavior and showed 60% response in 50 ppb HCHO concentration at 350 degrees C operating temperatures.

  15. Model of the radial distribution function of pores in a layer of porous aluminum oxide

    NASA Astrophysics Data System (ADS)

    Cherkas, N. L.; Cherkas, S. L.

    2016-03-01

    An empirical formula is derived to describe the quasi-periodic structure of a layer of porous aluminum oxide obtained by anodization. The formula accounts for two mechanisms of the transition from the ordered state (2D crystal) to the amorphous state. The first mechanism infers that vacancy-type defects arise, but the crystal lattice remains undestroyed. The second mechanism describes the lattice destruction. The radial distribution function of the pores in porous aluminum oxide is obtained using the Bessel transform. Comparison with a real sample is performed.

  16. Porous Nickel Oxide Film Sensor for Formaldehyde

    NASA Astrophysics Data System (ADS)

    Cindemir, U.; Topalian, Z.; Österlund, L.; Granqvist, C. G.; Niklasson, G. A.

    2014-11-01

    Formaldehyde is a volatile organic compound and a harmful indoor pollutant contributing to the "sick building syndrome". We used advanced gas deposition to fabricate highly porous nickel oxide (NiO) thin films for formaldehyde sensing. The films were deposited on Al2O3 substrates with prefabricated comb-structured electrodes and a resistive heater at the opposite face. The morphology and structure of the films were investigated with scanning electron microscopy and X-ray diffraction. Porosity was determined by nitrogen adsorption isotherms with the Brunauer-Emmett-Teller method. Gas sensing measurements were performed to demonstrate the resistive response of the sensors with respect to different concentrations of formaldehyde at 150 °C.

  17. Lubrication with Naturally Occurring Double Oxide Films

    DTIC Science & Technology

    1982-11-10

    sodium molybdate and tungstate at the sliding interface. Here the films were Identified. McDonald (27) showed that the presence of cobalt and molybdenum...activation energy of viscous flow. Whether the other oxides behaved in a similar manner has not been determined. For the molybdates and the tungstates the...Battelle (26) has found that molybdenum and tungsten are effective sliding materials for sodium and NaK. This has been attributed to the formation of

  18. CuO/ZnO coupled oxide films obtained by the electrodeposition technique and their photocatalytic activity in phenol degradation under solar irradiation.

    PubMed

    Paz, Diego S; Foletto, Edson L; Bertuol, Daniel A; Jahn, Sérgio L; Collazzo, Gabriela C; da Silva, Syllos S; Chiavone-Filho, Osvaldo; do Nascimento, Claudio A O

    2013-01-01

    CuO/ZnO coupled oxide films were electrodeposited onto an aluminum substrate and tested as photocatalysts in degradation of phenol molecules in aqueous solution under sunlight. The obtained films were characterized by X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results showed that the photocatalytic activity of films was significant, especially to coupled oxide film with a CuO/ZnO ratio equal to 0.697, which presented about 70% degradation of the aromatic molecules and 42% of total organic carbon (TOC) removal at 300 min under solar irradiation. Therefore, this work highlights the potential application of CuO/ZnO coupled oxide films obtained by electrodeposition onto aluminum substrate in the field of photocatalysis.

  19. Growth and morphology of sputtered aluminum thin films on P3HT surfaces.

    PubMed

    Kaune, Gunar; Metwalli, Ezzeldin; Meier, Robert; Körstgens, Volker; Schlage, Kai; Couet, Sebastien; Röhlsberger, Ralf; Roth, Stephan V; Müller-Buschbaum, Peter

    2011-04-01

    Growth and morphology of an aluminum (Al) contact on a poly(3-hexylthiophene) (P3HT) thin film are investigated with X-ray methods and related to the interactions at the Al:P3HT interface. Grazing incidence small-angle scattering (GISAXS) is applied in situ during Al sputter deposition to monitor the growth of the layer. A growth mode is found, in which the polymer surface is wetted and rapidly covered with a continuous layer. This growth type results in a homogeneous film without voids and is explained by the strong chemical interaction between Al and P3HT, which suppresses the formation of three-dimensional cluster structures. A corresponding three stage growth model (surface bonding, agglomeration, and layer growth) is derived. X-ray reflectivity shows the penetration of Al atoms into the P3HT film during deposition and the presence of a 2 nm thick intermixing layer at the Al:P3HT interface.

  20. PEALD YSZ-based bilayer electrolyte for thin film-solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Yu, Wonjong; Cho, Gu Young; Hong, Soonwook; Lee, Yeageun; Kim, Young Beom; An, Jihwan; Cha, Suk Won

    2016-10-01

    Yttria-stabilized zirconia (YSZ) thin film electrolyte deposited by plasma enhanced atomic layer deposition (PEALD) was investigated. PEALD YSZ-based bi-layered thin film electrolyte was employed for thin film solid oxide fuel cells on nanoporous anodic aluminum oxide substrates, whose electrochemical performance was compared to the cell with sputtered YSZ-based electrolyte. The cell with PEALD YSZ electrolyte showed higher open circuit voltage (OCV) of 1.0 V and peak power density of 182 mW cm-2 at 450 °C compared to the one with sputtered YSZ electrolyte(0.88 V(OCV), 70 mW cm-2(peak power density)). High OCV and high power density of the cell with PEALD YSZ-based electrolyte is due to the reduction in ohmic and activation losses as well as the gas and electrical current tightness.

  1. Addressing the Limit of Detectability of Residual Oxide Discontinuities in Friction Stir Butt Welds of Aluminum using Phased Array Ultrasound

    NASA Technical Reports Server (NTRS)

    Johnston, P. H.

    2008-01-01

    This activity seeks to estimate a theoretical upper bound of detectability for a layer of oxide embedded in a friction stir weld in aluminum. The oxide is theoretically modeled as an ideal planar layer of aluminum oxide, oriented normal to an interrogating ultrasound beam. Experimentally-measured grain scattering level is used to represent the practical noise floor. Echoes from naturally-occurring oxides will necessarily fall below this theoretical limit, and must be above the measurement noise to be potentially detectable.

  2. Corrosion resistance and durability of siloxane ceramic/polymer films for aluminum alloys in marine environments

    NASA Astrophysics Data System (ADS)

    Kusada, Kentaro

    The objective of this study is to evaluate corrosion resistance and durability of siloxane ceramic/polymer films for aluminum alloys in marine environments. Al5052-H3 and Al6061-T6 were selected as substrates, and HCLCoat11 and HCLCoat13 developed in the Hawaii Corrosion Laboratory were selected for the siloxane ceramic/polymer coatings. The HCLCoat11 is a quasi-ceramic coating that has little to no hydrocarbons in its structure. The HCLCoat13 is formulated to incorporate more hydrocarbons to improve adhesion to substrate surfaces with less active functionalities. In this study, two major corrosion evaluation methods were used, which were the polarization test and the immersion test. The polarization tests provided theoretical corrosion rates (mg/dm 2/day) of bare, HCLCoat11-coated, and HCLCoat13-coated aluminum alloys in aerated 3.15wt% sodium chloride solution. From these results, the HCLCoat13-coated Al5052-H3 was found to have the lowest corrosion rate which was 0.073mdd. The next lowest corrosion rate was 0.166mdd of the HCLCoat11-coated Al5052-H3. Corrosion initiation was found to occur at preexisting breaches (pores) in the films by optical microscopy and SEM analysis. The HCLCoat11 film had many preexisting breaches of 1-2microm in diameter, while the HCLCoat13 film had much fewer preexisting breaches of less than 1microm in diameter. However, the immersion tests showed that the seawater immersion made HCLCoat13 film break away while the HCLCoat11 film did not apparently degrade, indicating that the HCLCoat11 film is more durable against seawater than the HCLCoat13. Raman spectroscopy revealed that there was some degradation of HCLCoat11 and HCLCoat13. For the HCLCoat11 film, the structure relaxation of Si-O-Si linkages was observed. On the other hand, seawater generated C-H-S bonds in the HCLCoat13 film resulting in the degradation of the film. In addition, it was found that the HCLCoat11 coating had anti-fouling properties due to its high water contact

  3. Stimulating surface plasmon polaritons over patterned aluminum film by terahertz radiation

    NASA Astrophysics Data System (ADS)

    Zhu, Yaping; Li, Weijun; Luo, Jun; Yuan, Ying; Lei, Yu; Tong, Qing; Zhang, Xinyu; Xie, Changsheng

    2015-10-01

    In order to investigate the key properties of surface plasmon polaritons (SPPs), a new kind of device based on sub-wavelength aluminum structures (SWASs) have been designed and fabricated with respect to incident radiation in terahertz (THz) range. The device is composed of two layered micro-nano-structures and the utilized substrates are silicon materials in current stage. One silicon substrate is sputtered directly by a thin aluminum film, which is further patterned to shape functioned micro-nano-structures. The THz transmission performances of the devices have been measured according to common optical approaches. The experimental results show that some extraordinary transmission peaks are clearly presented in terahertz transmittance spectrum, which is inconsistent with the classical aperture theory of Bethe. The effects of the developed SPPs are discussed carefully according to the discovered phenomena about the extraordinary optical transmission (EOT).

  4. Epitaxial two dimensional aluminum films on silicon (111) by ultra-fast thermal deposition

    SciTech Connect

    Levine, Igal; Li Wenjie; Vilan, Ayelet; Yoffe, Alexander; Feldman, Yishay; Salomon, Adi

    2012-06-15

    Aluminum thin films are known for their extremely rough surface, which is detrimental for applications such as molecular electronics and photonics, where protrusions cause electrical shorts or strong scattering. We achieved atomically flat Al films using a highly non-equilibrium approach. Ultra-fast thermal deposition (UFTD), at rates >10 nm/s, yields RMS roughness of 0.4 to 0.8 nm for 30-50 nm thick Al films on variety of substrates. For UFTD on Si(111) substrates, the top surface follows closely the substrate topography (etch pits), indicating a 2D, layer-by-layer growth. The Al film is a mixture of (100) and (111) grains, where the latter are commensurate with the in-plane orientation of the underlying Si (epitaxy). We show the use of these ultra-smooth Al films for highly reproducible charge-transport measurements across a monolayer of alkyl phosphonic acid as well as for plasmonics applications by directly patterning them by focused ion beam to form a long-range ordered array of holes. UFTD is a one-step process, with no need for annealing, peeling, or primer layers. It is conceptually opposite to high quality deposition methods, such as MBE or ALD, which are slow and near-equilibrium processes. For Al, though, we find that limited diffusion length (and good wetting) is critical for achieving ultra-smooth thin films.

  5. Hysteresis-free high rate reactive sputtering of niobium oxide, tantalum oxide, and aluminum oxide

    SciTech Connect

    Särhammar, Erik Berg, Sören; Nyberg, Tomas

    2014-07-01

    This work reports on experimental studies of reactive sputtering from targets consisting of a metal and its oxide. The composition of the targets varied from pure metal to pure oxide of Al, Ta, and Nb. This combines features from both the metal target and oxide target in reactive sputtering. If a certain relation between the metal and oxide parts is chosen, it may be possible to obtain a high deposition rate, due to the metal part, and a hysteresis-free process, due to the oxide part. The aim of this work is to quantify the achievable boost in oxide deposition rate from a hysteresis-free process by using a target consisting of segments of a metal and its oxide. Such an increase has been previously demonstrated for Ti using a homogeneous substoichiometric target. The achievable gain in deposition rate depends on transformation mechanisms from oxide to suboxides due to preferential sputtering of oxygen. Such mechanisms are different for different materials and the achievable gain is therefore material dependent. For the investigated materials, the authors have demonstrated oxide deposition rates that are 1.5–10 times higher than what is possible from metal targets in compound mode. However, although the principle is demonstrated for oxides of Al, Ta, and Nb, a similar behavior is expected for most oxides.

  6. Metallic Thin-Film Bonding and Alloy Generation

    NASA Technical Reports Server (NTRS)

    Fryer, Jack Merrill (Inventor); Campbell, Geoff (Inventor); Peotter, Brian S. (Inventor); Droppers, Lloyd (Inventor)

    2016-01-01

    Diffusion bonding a stack of aluminum thin films is particularly challenging due to a stable aluminum oxide coating that rapidly forms on the aluminum thin films when they are exposed to atmosphere and the relatively low meting temperature of aluminum. By plating the individual aluminum thin films with a metal that does not rapidly form a stable oxide coating, the individual aluminum thin films may be readily diffusion bonded together using heat and pressure. The resulting diffusion bonded structure can be an alloy of choice through the use of a carefully selected base and plating metals. The aluminum thin films may also be etched with distinct patterns that form a microfluidic fluid flow path through the stack of aluminum thin films when diffusion bonded together.

  7. Large area Germanium Tin nanometer optical film coatings on highly flexible aluminum substrates

    PubMed Central

    Jin, Lichuan; Zhang, Dainan; Zhang, Huaiwu; Fang, Jue; Liao, Yulong; Zhou, Tingchuan; Liu, Cheng; Zhong, Zhiyong; Harris, Vincent G.

    2016-01-01

    Germanium Tin (GeSn) films have drawn great interest for their visible and near-infrared optoelectronics properties. Here, we demonstrate large area Germanium Tin nanometer thin films grown on highly flexible aluminum foil substrates using low-temperature molecular beam epitaxy (MBE). Ultra-thin (10–180 nm) GeSn film-coated aluminum foils display a wide color spectra with an absorption wavelength ranging from 400–1800 nm due to its strong optical interference effect. The light absorption ratio for nanometer GeSn/Al foil heterostructures can be enhanced up to 85%. Moreover, the structure exhibits excellent mechanical flexibility and can be cut or bent into many shapes, which facilitates a wide range of flexible photonics. Micro-Raman studies reveal a large tensile strain change with GeSn thickness, which arises from lattice deformations. In particular, nano-sized Sn-enriched GeSn dots appeared in the GeSn coatings that had a thickness greater than 50 nm, which induced an additional light absorption depression around 13.89 μm wavelength. These findings are promising for practical flexible photovoltaic and photodetector applications ranging from the visible to near-infrared wavelengths. PMID:27667259

  8. Large area Germanium Tin nanometer optical film coatings on highly flexible aluminum substrates

    NASA Astrophysics Data System (ADS)

    Jin, Lichuan; Zhang, Dainan; Zhang, Huaiwu; Fang, Jue; Liao, Yulong; Zhou, Tingchuan; Liu, Cheng; Zhong, Zhiyong; Harris, Vincent G.

    2016-09-01

    Germanium Tin (GeSn) films have drawn great interest for their visible and near-infrared optoelectronics properties. Here, we demonstrate large area Germanium Tin nanometer thin films grown on highly flexible aluminum foil substrates using low-temperature molecular beam epitaxy (MBE). Ultra-thin (10–180 nm) GeSn film-coated aluminum foils display a wide color spectra with an absorption wavelength ranging from 400–1800 nm due to its strong optical interference effect. The light absorption ratio for nanometer GeSn/Al foil heterostructures can be enhanced up to 85%. Moreover, the structure exhibits excellent mechanical flexibility and can be cut or bent into many shapes, which facilitates a wide range of flexible photonics. Micro-Raman studies reveal a large tensile strain change with GeSn thickness, which arises from lattice deformations. In particular, nano-sized Sn-enriched GeSn dots appeared in the GeSn coatings that had a thickness greater than 50 nm, which induced an additional light absorption depression around 13.89 μm wavelength. These findings are promising for practical flexible photovoltaic and photodetector applications ranging from the visible to near-infrared wavelengths.

  9. Large area Germanium Tin nanometer optical film coatings on highly flexible aluminum substrates.

    PubMed

    Jin, Lichuan; Zhang, Dainan; Zhang, Huaiwu; Fang, Jue; Liao, Yulong; Zhou, Tingchuan; Liu, Cheng; Zhong, Zhiyong; Harris, Vincent G

    2016-09-26

    Germanium Tin (GeSn) films have drawn great interest for their visible and near-infrared optoelectronics properties. Here, we demonstrate large area Germanium Tin nanometer thin films grown on highly flexible aluminum foil substrates using low-temperature molecular beam epitaxy (MBE). Ultra-thin (10-180 nm) GeSn film-coated aluminum foils display a wide color spectra with an absorption wavelength ranging from 400-1800 nm due to its strong optical interference effect. The light absorption ratio for nanometer GeSn/Al foil heterostructures can be enhanced up to 85%. Moreover, the structure exhibits excellent mechanical flexibility and can be cut or bent into many shapes, which facilitates a wide range of flexible photonics. Micro-Raman studies reveal a large tensile strain change with GeSn thickness, which arises from lattice deformations. In particular, nano-sized Sn-enriched GeSn dots appeared in the GeSn coatings that had a thickness greater than 50 nm, which induced an additional light absorption depression around 13.89 μm wavelength. These findings are promising for practical flexible photovoltaic and photodetector applications ranging from the visible to near-infrared wavelengths.

  10. The effect of oxide film properties on the corrosion behavior of SiC/Al metal-matrix composites

    SciTech Connect

    Golledge, S.L.

    1991-01-01

    Oxide growth on pure aluminum, aluminum alloy 6061, and the aluminum-based metal matrix composite SiC/AA6061 was studied, and the properties of the oxides related to the pit-initiation behavior of the materials. The objectives of the work were to identify the effect of alloying elements and SiC reinforcement on the oxide film, and to better understand how the oxide properties control pit initiation behavior. To this end, electrochemical and optical studies of the materials were carried out in a buffered sodium/boric acid solution at pH values of 8.4 and 7.2. The alloy and metal-matrix composite showed a slightly lesser tendency to pit than pure aluminum, as measured by the pitting potential. The oxide on the composite was less resistant to pit initiation, and was found to exhibit slower repassivation rates than the other materials. The repassivation behavior and resistance to pit initiation were quite similar in the case of the alloy and the pure aluminum. Induction times for pit initiation were consistent with the predictions of Heusler's model for the breakdown of passivity.

  11. Enhancement of oxidation resistance of NBD 200 silicon nitride ceramics by aluminum implantation

    NASA Astrophysics Data System (ADS)

    Mukundhan, Priya

    Silicon nitride (Si3N4) ceramics are leading candidates for high temperature structural applications. They have already demonstrated functional capabilities well beyond the limits of conventional metals and alloys in advanced diesel and turbine engines. However, the practical exploitation of these benefits is limited by their oxidation and associated degradation processes in chemically aggressive environments. Additives and impurities in Si3N4 segregate to the surface of Si3N 4 and accelerate its high temperature oxidation process. This study aims to investigate the oxidation behavior of Norton NBD 200 silicon nitride (hot isostatically pressed with ˜1 wt.% MgO) and its modification by aluminum surface alloying. NBD 200 samples tribochemically polished to a mirror finish (10 nm) were implanted with 5, 10, 20 and 30 at.% aluminum at multienergies and multi-doses to achieve a uniform implant depth distribution to 200 nm. Unimplanted and aluminum-implanted samples were oxidized at 800°--1100°C in 1 atm O2 for 0.5--10 hours. Oxidation kinetics was determined using profilometry in conjunction with etch patterning. The morphological, structural and chemical characteristics of the oxide were characterized by various analytical techniques such as scanning electron microscope and energy dispersive x-ray analysis, secondary ion mass spectrometry and x-ray photoelectron spectroscopy. Oxidation of NBD 200 follows parabolic kinetics in the temperature range investigated and the process is diffusion-controlled. The oxide layers are enriched with sodium and magnesium from the bulk of the Si3N 4. The much higher oxidation rate for NBD 200 silicon nitride than for other silicon nitride ceramics with a similar amount of MgO is attributed to the presence of sodium. The rate-controlling mechanism is the outward diffusion of Mg2+ from the grain boundaries to the oxide scale. Aluminum implantation alleviates the detrimental effects of Na+ and Mg2+; not only is the rate of oxidation

  12. The formation mechanism of aluminum oxide tunnel barriers.

    SciTech Connect

    Cerezo, A.; Petford-Long, A. K.; Larson, D. J.; Pinitsoontorn, S.; Singleton, E. W.; Materials Science Division; Univ. Oxford; Seagate Tech.

    2006-01-01

    The functional properties of magnetic tunnel junctions are critically dependant on the nanoscale morphology of the insulating barrier (usually only a few atomic layers thick) that separates the two ferromagnetic layers. Three-dimensional atom probe analysis has been used to study the chemistry of a magnetic tunnel junction structure comprising an aluminium oxide barrier formed by in situ oxidation, both in the under-oxidized and fully oxidized states and before and after annealing. Low oxidation times result in discrete oxide islands. Further oxidation leads to a more continuous, but still non-stoichiometric, barrier with evidence that oxidation proceeds along the top of grain boundaries in the underlying CoFe layer. Post-deposition annealing leads to an increase in the barrier area, but only in the case of the fully oxidized and annealed structure is a continuous planar layer formed, which is close to the stoichiometric Al:O ratio of 2:3. These results are surprising, in that the planar layers are usually considered unstable with respect to breaking up into separate islands. Analysis of the various driving forces suggests that the formation of a continuous layer requires a combination of factors, including the strain energy resulting from the expansion of the oxide during internal oxidation on annealing.

  13. In-situ measurement of the electrical conductivity of aluminum oxide in HFIR

    SciTech Connect

    Zinkle, S.J.; White, D.P.; Snead, L.L.

    1996-10-01

    A collaborative DOE/Monbusho irradiation experiment has been completed which measured the in-situ electrical resistivity of 12 different grades of aluminum oxide during HFIR neutron irradiation at 450{degrees}C. No evidence for bulk RIED was observed following irradiation to a maximum dose of 3 dpa with an applied dc electric field of 200 V/mm.

  14. Silicon nanoprofiling with the use of a solid aluminum oxide mask and combined 'dry' etching

    SciTech Connect

    Belov, A. N.; Demidov, Yu. A.; Putrya, M. G.; Golishnikov, A. A.; Vasilyev, A. A.

    2009-12-15

    Technological features of nanoprofiling of silicon protected by a solid mask based on porous aluminum oxide are considered. It is shown that, for a nanoprofiled silicon surface to be formed, it is advisable that combined dry etching be used including preliminary bombardment of structures with accelerated neutral atoms of an inert gas followed by reactive ion etching.

  15. Local etching of silicon using a solid mask from porous aluminum oxide

    SciTech Connect

    Belov, A. N.

    2008-12-15

    Technological features of nanoprofiling of silicon protected by a solid mask made of porous aluminum oxide are considered. It is shown that the method based on bombarding structures with accelerated neutral atoms (in particular, argon atoms) is efficient for etching through this mask.

  16. Spectroscopy of photonic band gaps in mesoporous one-dimensional photonic crystals based on aluminum oxide

    NASA Astrophysics Data System (ADS)

    Gorelik, V. S.; Voinov, Yu. P.; Shchavlev, V. V.; Bi, Dongxue; Shang, Guo Liang; Fei, Guang Tao

    2016-12-01

    Mesoporous one-dimensional photonic crystals based on aluminum oxide have been synthesized by electrochemical etching method. Reflection spectra of the obtained mesoporous samples in a wide spectral range that covers several band gaps are presented. Microscopic parameters of photonic crystals are calculated and corresponding reflection spectra for the first six band gaps are presented.

  17. Adsorption and catalytic properties of sulfated aluminum oxide modified with cobalt ions

    NASA Astrophysics Data System (ADS)

    Lanin, S. N.; Bannykh, A. A.; Vlasenko, E. V.; Krotova, I. N.; Obrezkov, O. N.; Shilina, M. I.

    2017-01-01

    The adsorption properties of sulfated aluminum oxide (9% SO 4 2- /γ-Al2O3) and a cobalt-containing composite (0.5%Co/SO 4 2- /γ-Al2O3) based on it are studied via dynamic sorption. The adsorption isotherms of such test adsorbates as n-hydrocarbons (C6-C8), benzene, ethylbenzene, chloroform, and diethyl ether are measured, and their isosteric heats of adsorption are calculated. It is shown that the surface sulfation of aluminum oxide substantially improves its electron-accepting properties, and so the catalytic activity of SO 4 2- /γ-Al2O3 in the liquid-phase alkylation of benzene with octene-1 at temperatures of 25-120°C is one order of magnitude higher than for the initial aluminum oxide. It is established that additional modification of sulfated aluminum oxide with cobalt ions increases the activity of this catalyst by 2-4 times. It is shown that adsorption sites capable of strong specific adsorption with both donating (aromatics, diethyl ether chemosorption) and accepting molecules (chloroform) form on the surface of sulfated γ-Al2O3 promoted by cobalt salt.

  18. 21 CFR 73.3110a - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section 73.3110a Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL... required to accomplish the intended coloring effect. (2) Authorization for this use shall not be...

  19. 21 CFR 73.3110a - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section 73.3110a Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL... required to accomplish the intended coloring effect. (2) Authorization for this use shall not be...

  20. Fabrication of GaN nanotubular material using MOCVD with aluminum oxide membrane

    NASA Astrophysics Data System (ADS)

    Jung, Woo-Gwang; Jung, Se-Hyuck; Kung, Patrick; Razeghi, Manijeh

    2006-02-01

    GaN nanotubular material is fabricated with aluminum oxide membrane in MOCVD. SEM, XRD, TEM and PL are employed to characterize the fabricated GaN nanotubular material. An aluminum oxide membrane with ordered nano holes is used as template. Gallium nitride is deposited at the inner wall of the nano holes in aluminum oxide template, and the nanotubular material with high aspect ratio is synthesized using the precursors of TMG and ammonia gas. Optimal synthesis condition in MOCVD is obtained successfully for the gallium nitride nanotubular material in this research. The diameter of GaN nanotube fabricated is approximately 200 ~ 250 nm and the wall thickness is about 40 ~ 50 nm. GaN nanotubular material consists of numerous fine GaN particulates with sizes ranging 15 to 30 nm. The composition of gallium nitride is confirmed to be stoichiometrically 1:1 for Ga and N by EDS. XRD and TEM analyses indicate that grains in GaN nanotubular material have nano-crystalline structure. No blue shift is found in the PL spectrum on the GaN nanotubular material fabricated in aluminum oxide template.

  1. Synthesis of aluminum oxide supported fluorescent gold nanodots for the detection of silver ions.

    PubMed

    Chen, Po-Cheng; Yeh, Ting-Yin; Ou, Chung-Mao; Shih, Chung-Chien; Chang, Huan-Tsung

    2013-06-07

    Photoluminescent gold nanodots (Au NDs) on aluminum oxide nanoparticles (Al2O3 NPs) with the emission wavelengths ranging from 510 to 630 nm are unveiled. Orange Al2O3 NP@AuNDs show high selectivity and sensitivity towards Ag(+) ions by metallophilic Ag(+)-Au(+) interactions and induced fluorescence quenching of Au NDs.

  2. Fabrication, structural characterization and sensing properties of polydiacetylene nanofibers templated from anodized aluminum oxide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polydiacetylene (PDA), a unique conjugated polymer, has shown its potential in the application of chem/bio-sensors and optoelectronics. In this work, we first infiltrated PDA monomer (10, 12-pentacosadiynoic acid, PCDA) melted into the anodized aluminum oxide template, and then illuminated the infil...

  3. Low oxidation state aluminum-containing cluster anions: Cp(∗)AlnH(-), n = 1-3.

    PubMed

    Zhang, Xinxing; Ganteför, Gerd; Eichhorn, Bryan; Mayo, Dennis; Sawyer, William H; Gill, Ann F; Kandalam, Anil K; Schnöckel, Hansgeorg; Bowen, Kit

    2016-08-21

    Three new, low oxidation state, aluminum-containing cluster anions, Cp*AlnH(-), n = 1-3, were prepared via reactions between aluminum hydride cluster anions, AlnHm (-), and Cp*H ligands. These were characterized by mass spectrometry, anion photoelectron spectroscopy, and density functional theory based calculations. Agreement between the experimentally and theoretically determined vertical detachment energies and adiabatic detachment energies validated the computed geometrical structures. Reactions between aluminum hydride cluster anions and ligands provide a new avenue for discovering low oxidation state, ligated aluminum clusters.

  4. Impurity effects on the adhesion of aluminum films on sapphire substrates

    SciTech Connect

    Schneider, J.A.; Guthrie, S.E.; Clift, W.M.; Moody, N.R.; Kriese, M.D.

    1998-05-01

    The adhesion of aluminum (Al) films onto sapphire substrates in the presence of controlled contaminants is being investigated. In this study, adhesion strength is evaluated by continuous scratch and nanoindentation tests to induce delamination of the Al film from the sapphire substrate. If delamination blisters or spallations can be induced, then fracture mechanics based models can be used to calculate the fracture energy or work of adhesion based on the radius of the blister. Initial specimens of 178 nm thick Al films were vapor deposited onto (0001) oriented sapphire substrates with a 5--19 nm layer of carbon sputter deposited onto the sapphire surface of selected samples. Continuous scratch tests promoted blistering of the film in specimens with carbon on the sapphire surface. Delamination blisters could not be induced by continuous indentation testing in samples with or without carbon at the interface. An overlayer of sputtered tantalum (Ta) was then used on a second set of 500 nm thick Al films with and without 10--20 nm of sputtered carbon on the sapphire surface to promote delaminations. With Ta overlayers, continuous nanoindentation techniques induced larger diameter delamination blisters in the specimens with carbon, than in the specimens without carbon. Resistance to blistering, or smaller induced blisters, indicates a higher interfacial strength.

  5. The immunogenicity of thin-film freeze-dried, aluminum salt-adjuvanted vaccine when exposed to different temperatures.

    PubMed

    Thakkar, Sachin G; Ruwona, Tinashe B; Williams, Robert O; Cui, Zhengrong

    2017-01-04

    Insoluble aluminum salts such as aluminum oxyhydroxide have been used for decades as adjuvants in human vaccines, and many vaccines contain aluminum salts as adjuvants. Aluminum salt-adjuvanted vaccines must be managed in cold-chain (2-8° C) during transport and storage, as vaccine antigens in general are too fragile to be stable in ambient temperatures, and unintentional slowing freezing causes irreversible aggregation and permanent damage to the vaccines. Previously, we reported that thin-film freeze-drying can be used to convert vaccines adjuvanted with an aluminum salt from liquid suspension into dry powder without causing particle aggregation or decreasing in immunogenicity following reconstitution. In the present study, using ovalbumin (OVA)-adsorbed Alhydrogel® (i.e. aluminum oxyhydroxide, 2% w/v) as a model vaccine, we showed that the immunogenicity of thin-film freeze-dried OVA-adsorbed Alhydrogel® vaccine powder was not significantly changed after it was exposed for an extended period of time in temperatures as high as 40° C or subjected to repeated slow freezing-and-thawing. It is expected that immunization programs can potentially benefit by integrating thin-film freeze-drying into vaccine preparations.

  6. Polyene Formation Catalyzed by Phosphotungstic Acid and Aluminum Chloride in Thin Films of Poly(Vinyl Alcohol)

    NASA Astrophysics Data System (ADS)

    Tretinnikov, O. N.; Sushko, N. I.; Maly, A. B.

    2016-01-01

    Formation of linear polyenes -(CH=CH) n - during thermal dehydration of thin layers (9-20 μm) of poly(vinyl alcohol) containing phosphotungstic-acid and aluminum-chloride catalysts was investigated. It was found that the concentration of long-chain ( n ≥ 8) polyenes in films containing phosphotungstic acid increased smoothly with increasing annealing time although the kinetics of the dehydration were independent of the film thickness. The polyene ( n ≥ 8) formation rate in films containing aluminum chloride dropped quickly with decreasing film thickness and increasing annealing time. As a result, long-chain polyenes practically did not form regardless of the annealing time for a film thickness of 11 μm.

  7. Bacopa monniera Stabilized Silver Nanoparticles Attenuates Oxidative Stress Induced by Aluminum in Albino Mice.

    PubMed

    Mahitha, B; Deva Prasad Raju, B; Mallikarjuna, K; Durga Mahalakshmi, Ch N; Sushmal, N John

    2015-02-01

    In the recent years usage of nanomedicine plays a promising strategy in the improvement of medical treatment. The ecofriendly synthesized silver nanoparticles has introduced a new opportunity to increase the efficacy of drug by reducing its side effects. In the present study, we investigated the antioxidant property of Bacopa monniera stabilized silver nanoparticles against aluminum induced toxicity in albino mice. Forty male albino mice were randomly divided into five groups. First group was treated as control, second group received aluminum acetate (5 mg/kg b . w), third group received Bacopa monniera extract (5 mg/kg b . w), fourth group received BmSNPs (5 mg/kg b . w), fifth group received aluminum acetate plus BmSNPs. Exposure to aluminum acetate significantly increased lipid peroxidation levels with a significant decrease in the antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase activities in the brain, liver and kidney of mice. Degenerative changes were also observed in brain, liver and kidney of aluminum treated mice. No significant changes in the oxidative stress were observed in the Bacopa monniera and BmSNPs alone treated mice. Whereas, co-administration of BmSNPs to Al treated mice showed a significant decrease in lipid peroxidation levels with a significant increase of SOD, CAT and GPx indicating the antioxidant potential of nanoparticles and in counteracting Al induced oxidative stress and histological response in male albino mice. These findings clearly implicate that BmSNPs are able to eradicate the oxidative stress and prevent the tissue damage in aluminum exposed mice.

  8. High quality ZnO:Al transparent conducting oxide films synthesized by pulsed filtered cathodic arc deposition

    SciTech Connect

    Anders, Andre; Lim, Sunnie H.N.; Yu, Kin Man; Andersson, Joakim; Rosen, Johanna; McFarland, Mike; Brown, Jeff

    2009-04-24

    Aluminum-doped zinc oxide, ZnO:Al or AZO, is a well-known n-type transparent conducting oxide with great potential in a number of applications currently dominated by indium tin oxide (ITO). In this study, the optical and electrical properties of AZO thin films deposited on glass and silicon by pulsed filtered cathodic arc deposition are systematically studied. In contrast to magnetron sputtering, this technique does not produce energetic negative ions, and therefore ion damage can be minimized. The quality of the AZO films strongly depends on the growth temperature while only marginal improvements are obtained with post-deposition annealing. The best films, grown at a temperature of about 200?C, have resistivities in the low to mid 10-4 Omega cm range with a transmittance better than 85percent in the visible part of the spectrum. It is remarkable that relatively good films of small thickness (60 nm) can be fabricated using this method.

  9. Formation of linear polyenes in poly(vinyl alcohol) films catalyzed by phosphotungstic acid, aluminum chloride, and hydrochloric acid

    NASA Astrophysics Data System (ADS)

    Tretinnikov, O. N.; Sushko, N. I.; Malyi, A. B.

    2016-07-01

    Formation of linear polyenes-(CH=CH)n-via acid-catalyzed thermal dehydration of polyvinyl alcohol in 9- to 40-µm-thick films of this polymer containing hydrochloric acid, aluminum chloride, and phosphotungstic acid as dehydration catalysts was studied by electronic absorption spectroscopy. The concentration of long-chain ( n ≥ 8) polyenes in films containing phosphotungstic acid is found to monotonically increase with the duration of thermal treatment of films, although the kinetics of this process is independent of film thickness. In films containing hydrochloric acid and aluminum chloride, the formation rate of polyenes with n ≥ 8 rapidly drops as film thickness decreases and the annealing time increases. As a result, at a film thickness of less than 10-12 µm, long-chain polyenes are not formed at all in these films no matter how long thermal duration is. The reason for this behavior is that hydrochloric acid catalyzing polymer dehydration in these films evaporates from the films during thermal treatment, the evaporation rate inversely depending on film thickness.

  10. Large area and broadband ultra-black absorber using microstructured aluminum doped silicon films

    NASA Astrophysics Data System (ADS)

    Liu, Zhen; Liu, Hai; Wang, Xiaoyi; Yang, Haigui; Gao, Jinsong

    2017-02-01

    A large area and broadband ultra-black absorber based on microstructured aluminum (Al) doped silicon (Si) films prepared by a low-cost but very effective approach is presented. The average absorption of the absorber is greater than 99% within the wide range from 350 nm to 2000 nm, and its size reaches to 6 inches. We investigate the fabrication mechanism of the absorber and find that the Al atom doped in silicon improves the formation of the nanocone-like microstructures on the film surface, resulting in a significant decrease in the reflection of incident light. The absorption mechanism is further discussed by experiments and simulated calculations in detail. The results show that the doped Al atoms and Mie resonance formed in the microstructures contribute the broadband super-high absorption.

  11. Atomic layer deposition of aluminum sulfide thin films using trimethylaluminum and hydrogen sulfide

    SciTech Connect

    Sinha, Soumyadeep; Sarkar, Shaibal K.; Mahuli, Neha

    2015-01-15

    Sequential exposures of trimethylaluminum and hydrogen sulfide are used to deposit aluminum sulfide thin films by atomic layer deposition (ALD) in the temperature ranging from 100 to 200 °C. Growth rate of 1.3 Å per ALD cycle is achieved by in-situ quartz crystal microbalance measurements. It is found that the growth rate per ALD cycle is highly dependent on the purging time between the two precursors. Increased purge time results in higher growth rate. Surface limited chemistry during each ALD half cycle is studied by in-situ Fourier transformed infrared vibration spectroscopy. Time of flight secondary ion-mass spectroscopy measurement is used to confirm elemental composition of the deposited films.

  12. Structural properties of a-Si films and their effect on aluminum induced crystallization

    SciTech Connect

    Tankut, Aydin; Ozkol, Engin; Karaman, Mehmet; Turan, Rasit; Canli, Sedat

    2015-10-15

    In this paper, we report the influence of the structural properties of amorphous silicon (a-Si) on its subsequent crystallization behavior via the aluminum induced crystallization (AIC) method. Two distinct a-Si deposition techniques, electron beam evaporation and plasma enhanced chemical vapor deposition (PECVD), are compared for their effect on the overall AIC kinetics as well as the properties of the final poly-crystalline (poly-Si) silicon film. Raman and FTIR spectroscopy results indicate that the PECVD grown a-Si films has higher intermediate-range order, which is enhanced for increased hydrogen dilution during deposition. With increasing intermediate-range order of the a-Si, the rate of AIC is diminished, leading larger poly-Si grain size.

  13. Wetting behavior and drag reduction of superhydrophobic layered double hydroxides films on aluminum

    NASA Astrophysics Data System (ADS)

    Zhang, Haifeng; Yin, Liang; Liu, Xiaowei; Weng, Rui; Wang, Yang; Wu, Zhiwen

    2016-09-01

    We present a novel method to fabricate Zn-Al LDH (layered double hydroxides) film with 3D flower-like micro-and nanostructure on the aluminum foil. The wettability of the Zn-Al LDH film can be easily changed from superhydrophilic to superhydrophobic with a simple chemical modification. The as-prepared superhydrophobic surfaces have water CAs (contact angles) of 165 ± 2°. In order to estimate the drag reduction property of the surface with different adhesion properties, the experimental setup of the liquid/solid friction drag is proposed. The drag reduction ratio for the as-prepared superhydrophobic sample is 20-30% at low velocity. Bearing this in mind, we construct superhydrophobic surfaces that have numerous technical applications in drag reduction field.

  14. Large area and broadband ultra-black absorber using microstructured aluminum doped silicon films

    PubMed Central

    Liu, Zhen; Liu, Hai; Wang, Xiaoyi; Yang, Haigui; Gao, Jinsong

    2017-01-01

    A large area and broadband ultra-black absorber based on microstructured aluminum (Al) doped silicon (Si) films prepared by a low-cost but very effective approach is presented. The average absorption of the absorber is greater than 99% within the wide range from 350 nm to 2000 nm, and its size reaches to 6 inches. We investigate the fabrication mechanism of the absorber and find that the Al atom doped in silicon improves the formation of the nanocone-like microstructures on the film surface, resulting in a significant decrease in the reflection of incident light. The absorption mechanism is further discussed by experiments and simulated calculations in detail. The results show that the doped Al atoms and Mie resonance formed in the microstructures contribute the broadband super-high absorption. PMID:28202899

  15. Several braze filler metals for joining an oxide-dispersion-strengthened nickel-chromium-aluminum alloy

    NASA Technical Reports Server (NTRS)

    Gyorgak, C. A.

    1975-01-01

    An evaluation was made of five braze filler metals for joining an aluminum-containing oxide dispersion-strengthened (ODS) alloy, TD-NiCrAl. All five braze filler metals evaluated are considered suitable for joining TD-NiCrAl in terms of wettability and flow. Also, the braze alloys appear to be tolerant of slight variations in brazing procedures since joints prepared by three sources using three of the braze filler metals exhibited similar brazing characteristics and essentially equivalent 1100 C stress-rupture properties in a brazed butt-joint configuration. Recommendations are provided for brazing the aluminum-containing ODS alloys.

  16. Oxidative addition of the C-I bond on aluminum nanoclusters

    NASA Astrophysics Data System (ADS)

    Sengupta, Turbasu; Das, Susanta; Pal, Sourav

    2015-07-01

    Energetics and the in-depth reaction mechanism of the oxidative addition step of the cross-coupling reaction are studied in the framework of density functional theory (DFT) on aluminum nanoclusters. Aluminum metal in its bulk state is totally inactive towards carbon-halogen bond dissociation but selected Al nanoclusters (size ranging from 3 to 20 atoms) have shown a significantly lower activation barrier towards the oxidative addition reaction. The calculated energy barriers are lower than the gold clusters and within a comparable range with the conventional and most versatile Pd catalyst. Further investigations reveal that the activation energies and other reaction parameters are highly sensitive to the geometrical shapes and electronic structures of the clusters rather than their size, imposing the fact that comprehensive studies on aluminum clusters can be beneficial for nanoscience and nanotechnology. To understand the possible reaction mechanism in detail, the reaction pathway is investigated with the ab initio Born Oppenheimer Molecular Dynamics (BOMD) simulation and the Natural Bond Orbital (NBO) analysis. In short, our theoretical study highlights the thermodynamic and kinetic details of C-I bond dissociation on aluminum clusters for future endeavors in cluster chemistry.Energetics and the in-depth reaction mechanism of the oxidative addition step of the cross-coupling reaction are studied in the framework of density functional theory (DFT) on aluminum nanoclusters. Aluminum metal in its bulk state is totally inactive towards carbon-halogen bond dissociation but selected Al nanoclusters (size ranging from 3 to 20 atoms) have shown a significantly lower activation barrier towards the oxidative addition reaction. The calculated energy barriers are lower than the gold clusters and within a comparable range with the conventional and most versatile Pd catalyst. Further investigations reveal that the activation energies and other reaction parameters are highly

  17. Controlled morphology of aluminum alloy nanopillar films: from nanohorns to nanoplates.

    PubMed

    Fujii, Takashi; Aoki, Yoshitaka; Fushimi, Koji; Makino, Takeshi; Ono, Shoji; Habazaki, Hiroki

    2010-10-01

    Nanopillar films of Al-Nb alloys have been fabricated on substrates with a regular concave cell structure by oblique angle physical vapor deposition. The concave cell structure of the substrate increases the shadow region for the flux of depositing atoms, assisting the formation of an isolated nanopillar on each cell. Depending upon the alloy composition and deposition angle, the pillar shape changes from horn-like nanopillars through triangular nanoprisms to nanoplates. The Al-Nb alloy nanoplate films with wide gaps between plates are of interest as electrodes for capacitor applications. The dielectric oxide film formed on the nanoplate film showed a capacitance more than ten times larger than that on the respective flat film, due to the enlarged surface area.

  18. The oxidation of aluminum at high temperature studied by Thermogravimetric Analysis and Differential Scanning Calorimetry.

    SciTech Connect

    Coker, Eric Nicholas

    2013-10-01

    The oxidation in air of high-purity Al foil was studied as a function of temperature using Thermogravimetric Analysis with Differential Scanning Calorimetry (TGA/DSC). The rate and/or extent of oxidation was found to be a non-linear function of the temperature. Between 650 and 750 ÀC very little oxidation took place; at 850 ÀC oxidation occurred after an induction period, while at 950 ÀC oxidation occurred without an induction period. At oxidation temperatures between 1050 and 1150 ÀC rapid passivation of the surface of the aluminum foil occurred, while at 1250 ÀC and above, an initial rapid mass increase was observed, followed by a more gradual increase in mass. The initial rapid increase was accompanied by a significant exotherm. Cross-sections of oxidized specimens were characterized by scanning electron microscopy (SEM); the observed alumina skin thicknesses correlated qualitatively with the observed mass increases.

  19. Positive ion emission from oxidized aluminum during ultraviolet excimer laser irradiation

    SciTech Connect

    Khan, Enamul; Langford, S. C.; Dickinson, J. T.

    2011-07-15

    We report quadrupole mass-selected time-of-flight measurements of positive ions from oxidized aluminum metal (and for comparison, single-crystal sapphire) during pulsed excimer laser irradiation at 193 and 248 nm. This work focuses on laser fluences well below onset of rapid etching or optical breakdown. By far the most intense emissions are due to Al{sup +}. On previously unexposed material, the ion kinetic energies are initially well above the photon energy, consistent with the ejection of Al{sup +} sorbed at surface electron traps. During prolonged irradiation, the emission intensities and kinetic energies gradually fall. Emission from patches of oxide would account for previous reports of laser-induced Al{sup +} emission from metallic aluminum surfaces cleaned by ion etching if patches of thin oxide were to survive the etching treatment.

  20. Combined flame and electrodeposition synthesis of energetic coaxial tungsten-oxide/aluminum nanowire arrays.

    PubMed

    Dong, Zhizhong; Al-Sharab, Jafar F; Kear, Bernard H; Tse, Stephen D

    2013-09-11

    A nanostructured thermite composite comprising an array of tungsten-oxide (WO2.9) nanowires (diameters of 20-50 nm and lengths of >10 μm) coated with single-crystal aluminum (thickness of ~16 nm) has been fabricated. The method involves combined flame synthesis of tungsten-oxide nanowires and ionic-liquid electrodeposition of aluminum. The geometry not only presents an avenue to tailor heat-release characteristics due to anisotropic arrangement of fuel and oxidizer but also eliminates or minimizes the presence of an interfacial Al2O3 passivation layer. Upon ignition, the energetic nanocomposite exhibits strong exothermicity, thereby being useful for fundamental study of aluminothermic reactions as well as enhancing combustion characteristics.

  1. Effects of aluminum and extremely low frequency electromagnetic radiation on oxidative stress and memory in brain of mice.

    PubMed

    Deng, Yuanxin; Zhang, Yanwen; Jia, Shujie; Liu, Junkang; Liu, Yanxia; Xu, Weiwei; Liu, Lei

    2013-12-01

    This study was aimed to investigate the effect of aluminum and extremely low-frequency magnetic fields (ELF-MF) on oxidative stress and memory of SPF Kunming mice. Sixty male SPF Kunming mice were divided randomly into four groups: control group, ELF-MF group (2 mT, 4 h/day), load aluminum group (200 mg aluminum/kg, 0.1 ml/10 g), and ELF-MF + aluminum group (2 mT, 4 h/day, 200 mg aluminum/kg). After 8 weeks of treatment, the mice of three experiment groups (ELF-MF group, load aluminum group, and ELF-MF + aluminum group) exhibited firstly the learning memory impairment, appearing that the escaping latency to the platform was prolonged and percentage in the platform quadrant was reduced in the Morris water maze (MWM) task. Secondly are the pathologic abnormalities including neuronal cell loss and overexpression of phosphorylated tau protein in the hippocampus and cerebral cortex. On the other hand, the markers of oxidative stress were determined in mice brain and serum. The results showed a statistically significant decrease in superoxide dismutase activity and increase in the levels of malondialdehyde in the ELF-MF group (P < 0.05 or P < 0.01), load aluminum group (P < 0.01), and ELF-MF + aluminum group (P < 0.01). However, the treatment with ELF-MF + aluminum induced no more damage than ELF-MF and aluminum did, respectively. In conclusion, both aluminum and ELF-MF could impact on learning memory and pro-oxidative function in Kunming mice. However, there was no evidence of any association between ELF-MF exposure with aluminum loading.

  2. Electrochromism: from oxide thin films to devices

    NASA Astrophysics Data System (ADS)

    Rougier, A.; Danine, A.; Faure, C.; Buffière, S.

    2014-03-01

    In respect of their adaptability and performance, electrochromic devices, ECDs, which are able to change their optical properties under an applied voltage, have received significant attention. Target applications are multifold both in the visible region (automotive sunroofs, smart windows, ophthalmic lenses, and domestic appliances (oven, fridge…)) and in the infrared region (Satellites Thermal Control, IR furtivity). In our group, focusing on oxide thin films grown preferentially at room temperature, optimization of ECDs performances have been achieved by tuning the microstructure, the stoichiometry and the cationic composition of the various layers. Herein, our approach for optimized ECDs is illustrated through the example of WO3 electrochromic layer in the visible and in the IR domain as well as ZnO based transparent conducting oxide layer. Targeting the field of printed electronics, simplification of the device architecture for low power ECDs is also reported.

  3. Augmentation of aluminum-induced oxidative stress in rat cerebrum by presence of pro-oxidant (graded doses of ethanol) exposure.

    PubMed

    Nayak, Prasunpriya; Sharma, Shiv Bhushan; Chowdary, Nadella Vijaya Subbaraya

    2010-11-01

    Both aluminum and ethanol are pro-oxidants and neurotoxic. Considering the possibilities of co-exposure and sharing mechanisms of producing neurotoxicity, the present study was planned to identify the level of aluminum-induced oxidative stress in altered pro-oxidant (ethanol exposure) status of cerebrum. Male rats were coexposed to aluminum and ethanol for 4 weeks. After the exposure period, cerebral levels of protein, reduced glutathione (GSH), lipid peroxidation (TBARS) were measured. Activities of catalase, superoxide dismutase (SOD), glutathione reductase (GR) and glutathione perioxidase (GPx) of cerebrum were estimated. In most of the cases significant correlations were observed between the alterations and graded ethanol doses, suggesting a dose-dependency in pushing the oxidant equilibrium toward pro-oxidants. Aluminum is found to influence significantly all the studied parameters of oxidative stress. Likewise, ethanol also influenced these parameters significantly, except GR, while the interaction between ethanol and aluminum could significantly influence only the GSH content and GR activity of cerebrum. Present study demonstrate that coexposure of aluminum with pro-oxidant might favor development of aluminum-induced oxidative stress in cerebrum. This observation might be helpful in understanding of mechanism of neurodegenerative disorders and ameliorate them.

  4. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... oxide may be safely used for coloring linear polyethylene surgical sutures, United States Pharmacopeia... procedure, the color additive is blended with the polyethylene resin. The mixture is heated to a...

  5. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... oxide may be safely used for coloring linear polyethylene surgical sutures, United States Pharmacopeia... procedure, the color additive is blended with the polyethylene resin. The mixture is heated to a...

  6. Aluminum cladding oxidation of prefilmed in-pile fueled experiments

    NASA Astrophysics Data System (ADS)

    Marcum, W. R.; Wachs, D. M.; Robinson, A. B.; Lillo, M. A.

    2016-04-01

    A series of fueled irradiation experiments were recently completed within the Advanced Test Reactor Full size plate In center flux trap Position (AFIP) and Gas Test Loop (GTL) campaigns. The conduct of the AFIP experiments supports ongoing efforts within the global threat reduction initiative (GTRI) to qualify a new ultra-high loading density low enriched uranium-molybdenum fuel. This study details the characterization of oxide growth on the fueled AFIP experiments and cross-correlates the empirically measured oxide thickness values to existing oxide growth correlations and convective heat transfer correlations that have traditionally been utilized for such an application. This study adds new and valuable empirical data to the scientific community with respect to oxide growth measurements of highly irradiated experiments, of which there is presently very limited data. Additionally, the predicted oxide thickness values are reconstructed to produce an oxide thickness distribution across the length of each fueled experiment (a new application and presentation of information that has not previously been obtainable in open literature); the predicted distributions are compared against experimental data and in general agree well with the exception of select outliers.

  7. The Oxidation Products of Aluminum Hydride and Boron Aluminum Hydride Clusters

    DTIC Science & Technology

    2016-01-04

    a solid with six crystalline phases. In principle, alane is a promising propellant . The specific impulse of an AP/HTPB propellant mixed with alane...Distribution approved for public release. 2     Introduction Boranes (boron hydrides) were once thought to be promising propellants .1-14 The reasons...diborane, hydrogen, and a white solid . Whatley et al.8 studied the products of diborane oxidation. Roth and co-workers9 found HOBO to be the main

  8. Influence of aluminum oxide on the prebiotic thermal synthesis of Gly-Glu-(Gly-Glu)(n) polymer.

    PubMed

    Leyton, Patricio; Zárate, R Antonio; Fuentes, Sandra; Paipa, Carolina; Gómez-Jeria, Juan S; Leyton, Yessica

    2011-01-01

    The effect of the aluminum oxide on the thermal synthesis of the glycine-glutamic acid (Gly-Glu-(Gly-Glu)(n) polymer is described. The thermal synthesis in the molten state was carried out in the absence and presence of the oxide. In both cases, the vibrational spectra showed characteristic group frequencies corresponding predominantly to a Gly-Glu-(Gly-Glu)(n) sequence in the polymeric structure. The theoretical spectral data support the experimental proposed Gly-Glu-(Gly-Glu)(n) sequence for the polymer. The SEM-EDX characterization of the solid phase involved in the thermal synthesis showed that the aluminum oxide participates as a site for nucleation and growth of the polymer, explaining the increase of 25% efficiency in the presence of aluminum oxide. Electrophoresis data show shorter polypeptide chains in the presence of aluminum oxide.

  9. Dysprosium oxide and dysprosium-oxide-doped titanium oxide thin films grown by atomic layer deposition

    SciTech Connect

    Tamm, Aile Kozlova, Jekaterina; Aarik, Lauri; Aarik, Jaan; Kukli, Kaupo; Link, Joosep; Stern, Raivo

    2015-01-15

    Dysprosium oxide and dysprosium-oxide-doped titanium oxide thin films were grown by atomic layer deposition on silicon substrates. For depositing dysprosium and titanium oxides Dy(thd){sub 3}-O{sub 3} and TiCl{sub 4}-O{sub 3} were used as precursors combinations. Appropriate parameters for Dy(thd){sub 3}-O{sub 3} growth process were obtained by using a quartz crystal microbalance system. The Dy{sub 2}O{sub 3} films were deposited on planar substrates and on three-dimensional substrates with aspect ratio 1:20. The Dy/Ti ratio of Dy{sub 2}O{sub 3}-doped TiO{sub 2} films deposited on a planar silicon substrate ranged from 0.04 to 0.06. Magnetometry studies revealed that saturation of magnetization could not be observed in planar Dy{sub 2}O{sub 3} films, but it was observable in Dy{sub 2}O{sub 3} films on 3D substrates and in doped TiO{sub 2} films with a Dy/Ti atomic ratio of 0.06. The latter films exhibited saturation magnetization 10{sup −6} A cm{sup 2} and coercivity 11 kA/m at room temperature.

  10. Generation of fast propagating combustion and shock waves with copper oxide/aluminum nanothermite composites

    NASA Astrophysics Data System (ADS)

    Apperson, S.; Shende, R. V.; Subramanian, S.; Tappmeyer, D.; Gangopadhyay, S.; Chen, Z.; Gangopadhyay, K.; Redner, P.; Nicholich, S.; Kapoor, D.

    2007-12-01

    Nanothermite composites containing metallic fuel and inorganic oxidizer are gaining importance due to their outstanding combustion characteristics. In this paper, the combustion behaviors of copper oxide/aluminum nanothermites are discussed. CuO nanorods were synthesized using the surfactant-templating method, then mixed or self-assembled with Al nanoparticles. This nanoscale mixing resulted in a large interfacial contact area between fuel and oxidizer. As a result, the reaction of the low density nanothermite composite leads to a fast propagating combustion, generating shock waves with Mach numbers up to 3.

  11. Fabrication of SERS-active substrates using silver nanofilm-coated porous anodic aluminum oxide for detection of antibiotics.

    PubMed

    Chen, Jing; Feng, Shaolong; Gao, Fang; Grant, Edward; Xu, Jie; Wang, Shuo; Huang, Qian; Lu, Xiaonan

    2015-04-01

    We have developed a silver nanofilm-coated porous anodic aluminum oxide (AAO) as a surface-enhanced Raman scattering (SERS)-active substrate for the detection of trace level of chloramphenicol, a representative antibiotic in food systems. The ordered aluminum template generated during the synthesis of AAO serves as a patterned matrix on which a coated silver film replicates the patterned AAO matrix to form a 2-dimensional ordered nanostructure. We used atomic force microscopy and scanning electron microscopy images to determine the morphology of this nanosubstrate, and characterized its localized surface plasmon resonance by ultraviolet-visible reflection. We gauged the SERS effect of this nanosubstrate by confocal micro-Raman spectroscopy (782-nm laser), finding a satisfactory and consistent performance with enhancement factors of approximately 2 × 10(4) and a limit of detection for chloramphenicol of 7.5 ppb. We applied principal component analysis to determine the limit of quantification for chloramphenicol of 10 ppb. Using electromagnetic field theory, we developed a detailed mathematical model to explain the mechanism of Raman signal enhancement of this nanosubstrate. With simple sample pretreatment and separation steps, this silver nanofilm-coated AAO substrate could detect 50 ppb chloramphenicol in milk, indicating good potential as a reliable SERS-active substrate for rapid detection of chemical contaminants in agricultural and food products.

  12. Highly Transparent and Flexible Triboelectric Nanogenerators with Subwavelength-Architectured Polydimethylsiloxane by a Nanoporous Anodic Aluminum Oxide Template.

    PubMed

    Dudem, Bhaskar; Ko, Yeong Hwan; Leem, Jung Woo; Lee, Soo Hyun; Yu, Jae Su

    2015-09-23

    Highly transparent and flexible triboelectric nanogenerators (TENGs) were fabricated using the subwavelength-architectured (SWA) polydimethylsiloxane (PDMS) with a nanoporous anodic aluminum oxide (AAO) template as a replica mold. The SWA PDMS could be utilized as a multifunctional film for a triboelectric layer, an antireflection coating, and a self-cleaning surface. The nanopore arrays of AAO were formed by a simple, fast, and cost-effective electrochemical oxidation process of aluminum, which is relatively impressive for fabrication of the TENG device. For electrical contacts, the SWA PDMS was laminated on the indium tin oxide (ITO)-coated polyethylene terephthalate (PET) as a bottom electrode, and the bare ITO-coated PET (i.e., ITO/PET) was used for the top electrode. Compared to the ITO/PET, the SWA PDMS on the ITO/PET improved the transmittance from 80.5 to 83% in the visible wavelength region and also had high transmittances of >85% at wavelengths of 430-455 nm. The SWA PDMS also exhibited the hydrophobic surface with a water contact angle (θCA) of ∼115°, which can be useful for self-cleaning applications. The average transmittance (Tavg) of the entire TENG device was observed to be ∼70% over a broad wavelength range. At an external pushing frequency of 0.5 Hz, for the TENG device with the ITO top electrode, open-circuit voltage (VOC) and short-circuit current (ISC) values of ∼3.8 V and ∼0.8 μA were obtained instantaneously, respectively, which were higher than those (i.e., VOC ≈ 2.2 V, and ISC ≈ 0.4 μA) of the TENG device with a gold top electrode. The effect of external pushing force and frequency on the output device performance of the TENGs was investigated, including the device robustness. A theoretical optical analysis of SWA PDMS was also performed.

  13. High carrier concentration p-type transparent conducting oxide films

    DOEpatents

    Yan, Yanfa; Zhang, Shengbai

    2005-06-21

    A p-type transparent conducting oxide film is provided which is consisting essentially of, the transparent conducting oxide and a molecular doping source, the oxide and doping source grown under conditions sufficient to deliver the doping source intact onto the oxide.

  14. Method of producing solution-derived metal oxide thin films

    DOEpatents

    Boyle, Timothy J.; Ingersoll, David

    2000-01-01

    A method of preparing metal oxide thin films by a solution method. A .beta.-metal .beta.-diketonate or carboxylate compound, where the metal is selected from groups 8, 9, 10, 11, and 12 of the Periodic Table, is solubilized in a strong Lewis base to form a homogeneous solution. This precursor solution forms within minutes and can be deposited on a substrate in a single layer or a multiple layers to form a metal oxide thin film. The substrate with the deposited thin film is heated to change the film from an amorphous phase to a ceramic metal oxide and cooled.

  15. Method of producing solution-derived metal oxide thin films

    SciTech Connect

    Boyle, T.J.; Ingersoll, D.

    2000-07-11

    A method is described for preparing metal oxide thin films by a solution method. A {beta}-metal {beta}-diketonate or carboxylate compound, where the metal is selected from groups 8, 9, 10, 11, and 12 of the Periodic Table, is solubilized in a strong Lewis base to form a homogeneous solution. This precursor solution forms within minutes and can be deposited on a substrate in a single layer or a multiple layers to form a metal oxide thin film. The substrate with the deposited thin film is heated to change the film from an amorphous phase to a ceramic metal oxide and cooled.

  16. Effects of oxidative treatments on human hair keratin films.

    PubMed

    Fujii, T; Ito, Y; Watanabe, T; Kawasoe, T

    2012-01-01

    The effects of hydrogen peroxide and commercial bleach on hair and human hair keratin films were examined by protein solubility, scanning electron microscopy (SEM), immunofluorescence microscopy, immunoblotting, and Fourier-transform infrared spectroscopy. Protein solubility in solutions containing urea decreased when the keratin films were treated with hydrogen peroxide or bleach. Oxidative treatments promoted the urea-dependent morphological change by turning films from opaque to transparent in appearance. Immunofluorescence microscopy and immunoblotting showed that the oxidation of amino acids and proteins occurred due to the oxidative treatments, and such occurrence was more evident in the bleach-treated films than in the hydrogen peroxide-treated films. Compared with hair samples, the formation of cysteic acid was more clearly observed in the keratin films after the oxidative treatments.

  17. Aluminum Induces Oxidative Stress Genes in Arabidopsis thaliana1

    PubMed Central

    Richards, Keith D.; Schott, Eric J.; Sharma, Yogesh K.; Davis, Keith R.; Gardner, Richard C.

    1998-01-01

    Changes in gene expression induced by toxic levels of Al were characterized to investigate the nature of Al stress. A cDNA library was constructed from Arabidopsis thaliana seedlings treated with Al for 2 h. We identified five cDNA clones that showed a transient induction of their mRNA levels, four cDNA clones that showed a longer induction period, and two down-regulated genes. Expression of the four long-term-induced genes remained at elevated levels for at least 48 h. The genes encoded peroxidase, glutathione-S-transferase, blue copper-binding protein, and a protein homologous to the reticuline:oxygen oxidoreductase enzyme. Three of these genes are known to be induced by oxidative stresses and the fourth is induced by pathogen treatment. Another oxidative stress gene, superoxide dismutase, and a gene for Bowman-Birk protease inhibitor were also induced by Al in A. thaliana. These results suggested that Al treatment of Arabidopsis induces oxidative stress. In confirmation of this hypothesis, three of four genes induced by Al stress in A. thaliana were also shown to be induced by ozone. Our results demonstrate that oxidative stress is an important component of the plant's reaction to toxic levels of Al. PMID:9449849

  18. Electrochemical properties of an aluminum anode in an ionic liquid electrolyte for rechargeable aluminum-ion batteries.

    PubMed

    Choi, Sangwon; Go, Hyungho; Lee, Gibaek; Tak, Yongsug

    2017-02-01

    An aluminum metal, both native and with a very thin oxide film, was investigated as an anode for aluminum-ion batteries. Investigations were carried out in an acidic ionic liquid electrolyte, composed of AlCl3 in 1-ethyl-3-methylimidazolium chloride ([EMIm]Cl), with β-MnO2/C as a cathode. The battery based on Al metal with a very thin oxide film showed high capacity and stable surface corrosion.

  19. Characterization of gadolinium and lanthanum oxide films on Si (100)

    NASA Astrophysics Data System (ADS)

    Wu, X.; Landheer, D.; Sproule, G. I.; Quance, T.; Graham, M. J.; Botton, G. A.

    2002-05-01

    High-resolution transmission electron microscopy, electron energy loss spectroscopy, and Auger electron spectroscopy, were used to study gadolinium and lanthanum oxide films deposited on Si (100) substrates using electron-beam evaporation from pressed-powder targets. As-deposited films consist of a crystalline oxide layer and an amorphous interfacial layer. A complicated distinct multilayer structure consisting of oxide layers, silicate layers, and SiO2-rich layers in thick (~30 nm) annealed films has been observed for both gadolinium and lanthanum films. For thinner annealed films (~8 nm), there is no longer a crystalline oxide layer but an amorphous gadolinium or lanthanum silicate layer and an interfacial SiO2-rich layer. The formation of the lanthanum silicate by annealing lanthanum oxide is found to be thermodynamically more favorable than the formation of gadolinium silicate.

  20. Flexible electrostatic nanogenerator using graphene oxide film

    NASA Astrophysics Data System (ADS)

    Tian, He; Ma, Shuo; Zhao, Hai-Ming; Wu, Can; Ge, Jie; Xie, Dan; Yang, Yi; Ren, Tian-Ling

    2013-09-01

    Recently, graphene oxide (GO) super capacitors with ultra-high energy densities have received significant attention. In addition to their use in energy storage, GO capacitors might also have broad applications in renewable energy engineering, such as energy harvesting. Here, a flexible nanogenerator based on GO film is designed. A multilayer structure Al/PI/GO/PI/ITO is made on a flexible PET substrate. The GO nanogenerator could generate a peak voltage of 2 V with a current of 30 nA upon the repetitive application of a 15 N force with a frequency of 1 Hz. Moreover, the output voltage was increased to 34.4 V upon increasing the frequency of force application to 10 Hz. Compared with control samples, embedding GO film with a release structure into the device could significantly enhance the output voltage from 0.1 V to 2.0 V. The mechanism of our nanogenerator can be explained by an electrostatic effect, which is fundamentally different from that of previously reported piezoelectric and triboelectric generators. In this manuscript, we demonstrate flexible nanogenerators with large-area graphene based materials, which may open up new avenues of research with regard to applications in energy harvesting.Recently, graphene oxide (GO) super capacitors with ultra-high energy densities have received significant attention. In addition to their use in energy storage, GO capacitors might also have broad applications in renewable energy engineering, such as energy harvesting. Here, a flexible nanogenerator based on GO film is designed. A multilayer structure Al/PI/GO/PI/ITO is made on a flexible PET substrate. The GO nanogenerator could generate a peak voltage of 2 V with a current of 30 nA upon the repetitive application of a 15 N force with a frequency of 1 Hz. Moreover, the output voltage was increased to 34.4 V upon increasing the frequency of force application to 10 Hz. Compared with control samples, embedding GO film with a release structure into the device could

  1. Solution-based deposition of ultrathin metal oxide films on metal and superconductor surfaces

    NASA Astrophysics Data System (ADS)

    Westwood, Glenn

    Solution chemical methods were used to deposit ultrathin metal oxide films on metal and superconductor surfaces. Platinum-molybdenum oxide films were deposited by spontaneous adsorption and electrodeposition of hexamolybdoplatinate, PtMO6O248-. Spectroscopic characterization by 17O and 195Pt NMR showed that the PtMo6O248- anion is stable in aqueous solution below pH 4. The interaction of this solution stable anion with Au and Ag was characterized by in situ scanning tunneling microscopy, x-ray photoelectron spectroscopy, and cyclic voltammetry. The anion was partially reduced upon adsorption on Ag, but spontaneously adsorbed on Au to form an amorphous surface phase. The electrodeposition of hexamolybdoplatinate on Au electrodes resulted in an electrode surface that was different from the spontaneously adsorbed species, in terms of composition, voltammetry, and reactivity. Cyclic voltammetry was also used to compare the reactivity of these materials for the electrooxidation of methanol. Ultrathin zirconia films were deposited on YBa2Cu3O 7-delta by alternating exposures to tetra n-propyl zirconate, Zr4(OPrn)16, and H2O in n-propanol. Physical and chemical characterization of these films was done by x-ray photoelectron spectroscopy, atomic force microscopy, and cross-section transmission electron microscopy. The zirconia films were determined to be ultrathin (<10 nm) and highly conformal to the surface of YBa2Cu3O7-delta. Metal-insulator-superconductor tunnel junctions fabricated in this fashion were characterized by current-voltage and conductivity-voltage measurements. Solution deposition from Zr4(OPrn) 16 was also used to deposit ultrathin zirconia films on gold, silver, and aluminum surfaces. X-ray photoelectron spectroscopy and atomic force microscopy were used to compare the physical properties of these films. Electrical measurements showed that zirconia films on Ag and Au are not insulating, but aluminum-zirconia-aluminum capacitors fabricated by this method

  2. Amorphous Vanadium Oxide/Carbon Composite Positive Electrode for Rechargeable Aluminum Battery.

    PubMed

    Chiku, Masanobu; Takeda, Hiroki; Matsumura, Shota; Higuchi, Eiji; Inoue, Hiroshi

    2015-11-11

    Amorphous vanadium oxide/carbon composite (V2O5/C) was first applied to the positive electrode active material for rechargeable aluminum batteries. Electrochemical properties of V2O5/C were investigated by cyclic voltammetry and charge-discharge tests. Reversible reduction/oxidation peaks were observed for the V2O5/C electrode and the rechargeable aluminum cell showed the maximum discharge capacity over 200 mAh g(-1) in the first discharging. The XPS analyses after discharging and the following charging exhibited that the redox of vanadium ion in the V2O5/C active material occurred during discharging and charging, and the average valence of V changed between 4.14 and 4.85.

  3. High Temperature Oxidation of Superalloys and Intermetallic Compounds

    DTIC Science & Technology

    2010-02-28

    material cost and density than austenitic and ferritic stainless steels [3,4]. They contain enough aluminum to form a thin film of aluminum oxide (in...1 t-\\ a) > —, :— sm . c) • / ""•••• Figure 8. Surface morphologies of...low material cost and density than austenitic and ferritic stainless steels [3,4]. They contain enough aluminum to form a thin film of aluminum oxide

  4. Confining a bi-enzyme inside the nanochannels of a porous aluminum oxide membrane for accelerating the enzymatic reactions.

    PubMed

    Shangguan, Li; Wei, Yuanqing; Liu, Xu; Yu, Jiachao; Liu, Songqin

    2017-02-28

    An artificial metabolon with high conversion efficiency was constructed by confining a bi-enzyme into porous aluminum oxide nanochannels, which accelerated enzymatic reactions by minimizing the diffusion loss of intermediate species.

  5. Film adhesive enhances neutron radiographic images

    NASA Technical Reports Server (NTRS)

    Reed, M. W.

    1978-01-01

    Resolution of neutron radiographic images of thermally conductive film is increased by replacing approximately 5 percent of aluminum powder, which provides thermal conductivity, with gadolinium oxide. Oxide is also chemically stable.

  6. Magnesium Recycling of Partially Oxidized, Mixed Magnesium-Aluminum Scrap through Combined Refining and Solid Oxide Membrane Electrolysis Processes

    SciTech Connect

    Xiaofei Guan; Peter A. Zink; Uday B. Pal; Adam C. Powell

    2012-01-01

    Pure magnesium (Mg) is recycled from 19g of partially oxidized 50.5wt.% Mg-Aluminum (Al) alloy. During the refining process, potentiodynamic scans (PDS) were performed to determine the electrorefining potential for magnesium. The PDS show that the electrorefining potential increases over time as the magnesium content inside the Mg-Al scrap decreases. Up to 100% percent of magnesium is refined from the Mg-Al scrap by a novel refining process of dissolving magnesium and its oxide into a flux followed by vapor phase removal of dissolved magnesium and subsequently condensing the magnesium vapor. The solid oxide membrane (SOM) electrolysis process is employed in the refining system to enable additional recycling of magnesium from magnesium oxide (MgO) in the partially oxidized Mg-Al scrap. The combination of the refining and SOM processes yields 7.4g of pure magnesium.

  7. Magnesium Recycling of Partially Oxidized, Mixed Magnesium-Aluminum Scrap Through Combined Refining and Solid Oxide Membrane (SOM) Electrolysis Processes

    SciTech Connect

    Guan, Xiaofei; Zink, Peter; Pal, Uday

    2012-03-11

    Pure magnesium (Mg) is recycled from 19g of partially oxidized 50.5wt.%Mg-Aluminum (Al) alloy. During the refining process, potentiodynamic scans (PDS) were performed to determine the electrorefining potential for magnesium. The PDS show that the electrorefining potential increases over time as the Mg content inside the Mg-Al scrap decreases. Up to 100% percent of magnesium is refined from the Mg-Al scrap by a novel refining process of dissolving magnesium and its oxide into a flux followed by vapor phase removal of dissolved magnesium and subsequently condensing the magnesium vapors in a separate condenser. The solid oxide membrane (SOM) electrolysis process is employed in the refining system to enable additional recycling of magnesium from magnesium oxide (MgO) in the partially oxidized Mg-Al scrap. The combination of the refining and SOM processes yields 7.4g of pure magnesium; could not collect and weigh all of the magnesium recovered.

  8. Energy dependence of the trapping of uranium atoms by aluminum oxide surfaces

    NASA Technical Reports Server (NTRS)

    Librecht, K. G.

    1979-01-01

    The energy dependence of the trapping probability for sputtered U-235 atoms striking an oxidized aluminum collector surface at energies between 1 eV and 184 eV was measured. At the lowest energies, approximately 10% of the uranium atoms are not trapped, while above 10 eV essentially all of them stick. Trapping probabilities averaged over the sputtered energy distribution for uranium incident on gold and mica are also presented.

  9. Effects of additives on volume change on melting, surface tension, and viscosity of liquid aluminum oxide

    NASA Technical Reports Server (NTRS)

    Bates, J. L.; Rasmussen, J. J.

    1972-01-01

    The effects of various oxide additives on the volume change on melting, the surface tension, and the viscosity of liquid Al2O3 were studied. Additives of Sm2O3, MgO, and Y2O3 which form solid solutions, compounds, and multiphase solids with Al2O3 were studied. A review of the property data for Al2O3 and Al2O3 containing oxide additives is presented. Oxide additives to Al2O3 reduce the volume change on melting and with the exception of SiO2 lower the viscosity; surface tensions change with oxide additives, but changes vary with different container material. Viscosity and volume change on melting appeared to be significantly more important for studying the properties of liquid oxides than surface tension. Supercooling of 270 K of yttrium aluminum garnet was observed.

  10. Thin films for micro solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Beckel, D.; Bieberle-Hütter, A.; Harvey, A.; Infortuna, A.; Muecke, U. P.; Prestat, M.; Rupp, J. L. M.; Gauckler, L. J.

    Thin film deposition as applied to micro solid oxide fuel cell (μSOFC) fabrication is an emerging and highly active field of research that is attracting greater attention. This paper reviews thin film (thickness ≤1 μm) deposition techniques and components relevant to SOFCs including current research on nanocrystalline thin film electrolyte and thin-film-based model electrodes. Calculations showing the geometric limits of μSOFCs and first results towards fabrication of μSOFCs are also discussed.

  11. Properties of aluminum-fluoride catalysts prepared by the fluoridation of aluminum oxide with trifluoromethane

    SciTech Connect

    McVicker, G.B.; Kim, C.J.; Eggert, J.J.

    1983-04-01

    High-purity AlF/sub 3/ has been prepared by allowing ..gamma..-Al/sub 2/O/sub 3/ to react with gaseous trifluoromethane at 670-770 K under 101 kPa total pressure. The use of gaseous trifluoromethane is a new, general method for preparing metal fluorides from metal oxides. AlF/sub 3/ prepared using this procedure retained the physical form of the starting ..gamma..-Al/sub 2/O/sub 3/. A 1/16-in. ..gamma..-Al/sub 2/O/sub 3/ extrudate, for example, yielded an AlF/sub 3/ extrudate with comparable physical dimensions and crush strengths. X-Ray diffraction, BET surface area, pore volume, and surface acidity measurements were employed to characterize various AlF/sub 3/ samples. Significant decreases in surface area and pore volume as well as surface acidity occurred upon increasing the concentration of AlF/sub 3/ from 90 to 100%. This behavior presumably results from the fluoridation of residual ..gamma..-Al/sub 2/O/sub 3/. AlF/sub 3/ extrudates were utilized as supports for Pt and Pd catalysts. Specific benzene hydrogenation activities of these catalysts are comparable to those of Pt and Pd on ..gamma..-Al/sub 2/O/sub 3/. In a unique application, Pd/AlF/sub 3/ was used to hydrogenate m-diethylbenzene in superacid (HF/TaF/sub 5/) solution.

  12. Substrate-dependent thermal conductivity of aluminum nitride thin-films processed at low temperature

    SciTech Connect

    Belkerk, B. E.; Bensalem, S.; Soussou, A.; Carette, M.; Djouadi, M. A.; Scudeller, Y.; Al Brithen, H.

    2014-12-01

    In this paper, we report on investigation concerning the substrate-dependent thermal conductivity (k) of Aluminum Nitride (AlN) thin-films processed at low temperature by reactive magnetron sputtering. The thermal conductivity of AlN films grown at low temperature (<200 °C) on single-crystal silicon (Si) and amorphous silicon nitride (SiN) with thicknesses ranging from 100 nm to 4000 nm was measured with the transient hot-strip technique. The k values for AlN films on SiN were found significantly lower than those on Silicon consistently with their microstructures revealed by X-ray diffraction, high resolution scanning electron microscopy, and transmission electron microscopy. The change in k was due to the thermal boundary resistance found to be equal to 10 × 10{sup −9} Km{sup 2}W{sup −1} on SiN against 3.5 × 10{sup −9} Km{sup 2}W{sup −1} on Si. However, the intrinsic thermal conductivity was determined with a value as high as 200 Wm{sup −1}K{sup −1} whatever the substrate.

  13. Oxidation behavior of nickel-chromium-aluminum-yttrium - Magnesium oxide and nickel-chromium-aluminum-yttrium - zirconate type of cermets

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, I.

    1976-01-01

    The 1100 and 1200 C cyclic oxidation resistance of dense Ni-Cr-Al-Y - MgO, Ni-Cr-Al-Y - CaZrO3, Ni-Cr-Al-Y - SrZrO3, Ni-Cr-Al-Y - MgZro3 cermets and a 70 percent dense Ni-Cr-Al-Y developmental material was determined. The cermets contained 60 and 50 volume percent of Ni-Cr-Al-Y which formed a matrix with the oxide particles imbedded in it. The cermets containing MgO were superior to cermets based on zirconates and to the porous Ni-Cr-Al-Y material.

  14. Silicon-based bridge wire micro-chip initiators for bismuth oxide-aluminum nanothermite

    NASA Astrophysics Data System (ADS)

    Staley, C. S.; Morris, C. J.; Thiruvengadathan, R.; Apperson, S. J.; Gangopadhyay, K.; Gangopadhyay, S.

    2011-11-01

    We present a micro-manufacturing process for fabricating silicon-based bridge wire micro-chip initiators with the capacity to liberate joules of chemical energy at the expense of micro joules of input electrical energy. The micro-chip initiators are assembled with an open material reservoir utilizing a novel 47 °C melting point solder alloy bonding procedure and integrated with a bismuth oxide-aluminum nanothermite energetic composite. The electro-thermal conversion efficiency of the initiators is enhanced by the use of a nanoporous silicon bed which impedes thermal coupling between the bridge wire and bulk silicon substrate while maintaining the structural integrity of the device. Electrical behaviors of the ignition elements are investigated to extract minimum input power and energy requirements of 382.4 mW and 26.51 µJ, respectively, both in the absence and presence of an injected bismuth oxide-aluminum nanothermite composition. Programmed combustion of bismuth oxide-aluminum nanothermite housed within these initiators is demonstrated with a success rate of 100% over a 30 to 80 µJ range of firing energies and ignition response times of less than 2 µs are achieved in the high input power operation regime. The micro-initiators reported here are intended for use in miniaturized actuation technologies.

  15. Hierarchical porous Ni@boehmite/nickel aluminum oxide flakes with enhanced microwave absorption ability.

    PubMed

    Zhao, Biao; Liu, Junwei; Guo, Xiaoqin; Zhao, Wanyu; Liang, Luyang; Ma, Chao; Zhang, Rui

    2017-03-29

    In this article, composites consisting of porous Ni cores coated with boehmite/nickel aluminum oxide nanoflakes were successfully prepared by a versatile method. The crystal constituents and shapes of the boehmite/nickel aluminum oxide nanoflakes were strongly influenced by reaction temperature, and their microwave absorption properties were investigated in terms of complex permittivity and permeability. The results reveal that the composites comprising porous Ni cores coated with boehmite/nickel aluminum oxide synthesized at 180 °C present superior absorption properties. The optimal reflection loss is -44.3 dB (>99.99% attenuation) at 14.4 GHz, and the effective absorption (below -10 dB) bandwidth can be monitored in the frequency range of 5.8-18.0 GHz for an absorber with thickness in the range of 1.5-3.5 mm. The high dissipation capability, good impedance match and multiple reflection of the porous flaky structure are responsible for the improvement in microwave absorption. Moreover, a new absorption mechanism was proposed for the porous structure. In this mechanism, the porous structure serves as a spreading container, which attenuates electromagnetic energy by prolonging the travel path and constrains waves in the void space to gradually consume energy. This method paves a new avenue to design porous magnetic-dielectric absorbing materials.

  16. Tunneling Spectroscopy Studies of Urea, Thiourea, and Selected Phosphonate Molecules Adsorbed on Aluminum Oxide

    NASA Astrophysics Data System (ADS)

    Crowder, Charles D.

    Experimental and calculated inelastic electron tunneling intensities were compared for several of the vibrational modes of thiourea adsorbed on aluminum oxide. The partial charge model of Kirtley, Scalapino, and Hansma was used to compute the theoretical intensities of each mode. The required partial charges were determined using a method developed by Momany. Essentially, the Coulomb potential resulting from point charges located at atom sites was fitted to the quantum mechanical electrostatic potential of a molecule calculated from Hartree-Fock theory. The effect of a vibrational mode pattern on the electrostatic potential of a molecule was investigated. This effect could not be acceptably modeled with a single point charge located on each atom, so one charge was used to represent the positive nucleus of each atom and a second charge was used to represent the valence cloud. The valence charge was allowed to move independently of the nuclear charge during a molecular vibration, and the motions of the two charges were found to be very different for hydrogen atoms. This model gave very reasonable agreement between the theoretical and observed relative intensities for the in plane vibrational modes of thiourea. An acceptable set of out of plane force constants could not be found. This caused problems in the interpretation of the out of plane relative intensities. Based on the in plane modes, it was concluded that thiourea bonded to aluminum oxide with the sulfur atom near the oxide and the sulfur-carbon bond perpendicular to the aluminum oxide surface. Quantum mechanical electrostatic potentials were also calculated for urea, phosphoric acid (PA), methylphosphonic acid (MPA), hydroxymethylphosphonic acid (HMP), and nitrotrismethylphosphonic acid (NTMP). Electron tunneling spectra were taken for PA, HMP and NTMP, and the observed frequencies were compared to values obtained from Fourier transform infrared, infrared and Raman spectroscopy. Upward shifts in the P=O and P

  17. Review of Zinc Oxide Thin Films

    DTIC Science & Technology

    2014-12-23

    Laboratory Air Force Materiel Command   a. REPORT U   b. ABSTRACT U   c. THIS PAGE U REPORT DOCUMENTATION PAGE Form ApprovedOMB No. 0704-0188 The public...PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION. 1.  REPORT DATE (DD-MM-YYYY)      18-12-2014 2.  REPORT TYPE      Final Performance 3.  DATES...Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18 1    Review of Zinc Oxide Thin Films   Abstract  The present review paper reports on the

  18. Surface scanning inspection system particle detection dependence on aluminum film morphology

    NASA Astrophysics Data System (ADS)

    Prater, Walter; Tran, Natalie; McGarvey, Steve

    2012-03-01

    Physical vapor deposition (PVD) aluminum films present unique challenges when detecting particulate defects with a Surface Scanning Inspection System (SSIS). Aluminum (Al) films 4500Å thick were deposited on 300mm particle grade bare Si wafers at two temperatures using a Novellus Systems INOVA® NExT,.. Film surface roughness and morphology measurements were performed using a Veeco Vx310® atomic force microscope (AFM). AFM characterization found the high deposition temperature (TD) Al roughness (Root Mean Square 16.5 nm) to be five-times rougher than the low-TD Al roughness (rms 3.7 nm). High-TD Al had grooves at the grain boundaries that were measured to be 20 to 80 nm deep. Scanning electron microscopy (SEM) examination, with a Hitachi RS6000 defect review SEM, confirmed the presence of pronounced grain grooves. SEM images established that the low-TD filmed wafers have fine grains (0.1 to 0.3 um diameter) and the high-TD film wafers have fifty-times larger equiaxed plateletshape grains (5 to 15 um diameter). Calibrated Poly-Styrene Latex (PSL) spheres ranging in size from 90 nm to 1 μm were deposited in circular patterns on the wafers using an aerosol deposition chamber. PSL sphere depositions at each spot were controlled to yield 2000 to 5000 counts. A Hitachi LS9100® dark field full wafer SSIS was used to experimentally determine the relationship of the PSL sphere scattered light intensity with S-polarized light, a measure of scattering cross-section, with respect to the calibrated PSL sphere diameter. Comparison of the SSIS scattered light versus PSL spot size calibration curves shows two distinct differences. Scattering cross-section (intensity) of the PSL spheres increased on the low-TD Al film with smooth surface roughness and the low-TD Al film defect detection sensitivity was 126 nm compared to 200 nm for the rougher high- TD Al film. This can be explained by the higher signal to noise attributed to the smooth low-TD Al. Dark field defect detection on

  19. Flexible electrostatic nanogenerator using graphene oxide film.

    PubMed

    Tian, He; Ma, Shuo; Zhao, Hai-Ming; Wu, Can; Ge, Jie; Xie, Dan; Yang, Yi; Ren, Tian-Ling

    2013-10-07

    Recently, graphene oxide (GO) super capacitors with ultra-high energy densities have received significant attention. In addition to their use in energy storage, GO capacitors might also have broad applications in renewable energy engineering, such as energy harvesting. Here, a flexible nanogenerator based on GO film is designed. A multilayer structure Al/PI/GO/PI/ITO is made on a flexible PET substrate. The GO nanogenerator could generate a peak voltage of 2 V with a current of 30 nA upon the repetitive application of a 15 N force with a frequency of 1 Hz. Moreover, the output voltage was increased to 34.4 V upon increasing the frequency of force application to 10 Hz. Compared with control samples, embedding GO film with a release structure into the device could significantly enhance the output voltage from 0.1 V to 2.0 V. The mechanism of our nanogenerator can be explained by an electrostatic effect, which is fundamentally different from that of previously reported piezoelectric and triboelectric generators. In this manuscript, we demonstrate flexible nanogenerators with large-area graphene based materials, which may open up new avenues of research with regard to applications in energy harvesting.

  20. Epitaxial Electrodeposition of Chiral Metal Oxide Films

    NASA Astrophysics Data System (ADS)

    Switzer, Jay

    2006-03-01

    Chirality is ubiquitous in Nature. One enantiomer of a molecule is often physiologically active, while the other enantiomer may be either inactive or toxic. Chiral surfaces offer the possibility of developing heterogeneous enantiospecific catalysts that can more readily be separated from the products and reused. Chiral surfaces might also serve as electrochemical sensors for chiral molecules- perhaps even implantable chiral sensors that could be used to monitor drug levels in the body. Our trick to produce chiral surfaces is to electrodeposit low symmetry metal oxide films with chiral orientations on achiral substrates (see, Nature 425, 490, 2003). The relationship between three-dimensional and two-dimensional chirality will be discussed. Chiral surfaces lack mirror or glide plane symmetry. It is possible to produce chiral surfaces of materials which do not crystallize in chiral space groups. We have deposited chiral orientations of achiral CuO onto single-crystal Au and Cu using both tartaric acid and the amino acids alanine and valine to control the handedness of the electrodeposited films. We will present results on the chiral recognition of molecules such as tartaric or malic acid and L-dopa on the chiral electrodeposited CuO. Initial work on the electrochemical biomineralization of chiral nanostructures of calcite will also be discussed.

  1. Aluminum Alloys--Industrial Deformable, Sintered and Light Aluminum Alloys

    DTIC Science & Technology

    1974-10-30

    thin film on the particles of the highly dispersed aluminum powder when it is ground in spherical mills in a nitrogen atmosphere in which the...principal elements, certain small admixtures are introduced into the alloys, which have a considerable effect on the decay kinetics of the oversaturated...strengthened by the insoluble dispersed alumina particles. Fine grinding of the original powder provides the dispersion of the oxide films and particles

  2. Determination of Ideal Broth Formulations Needed to Prepare Hydrous Aluminum Oxide Microspheres via the Internal Gelation Process

    SciTech Connect

    Collins, Jack Lee; Pye, S. L.

    2009-02-01

    A simple test-tube methodology was used to determine optimum process parameters for preparing hydrous aluminum oxide microspheres by the internal gelation process. Broth formulations of aluminum, hexamethylenetetramine, and urea were found that can be used to prepare hydrous aluminum oxide gel spheres in the temperature range of 60-90 C. A few gel-forming runs were made in which microspheres were prepared with some of these formulations in order to equate the test-tube gelation times with actual gelation times. These preparations confirmed that the test-tube methodology is reliable for determining the ideal broths.

  3. Systematic review of potential health risks posed by pharmaceutical, occupational and consumer exposures to metallic and nanoscale aluminum, aluminum oxides, aluminum hydroxide and its soluble salts

    PubMed Central

    Willhite, Calvin C.; Karyakina, Nataliya A.; Yokel, Robert A.; Yenugadhati, Nagarajkumar; Wisniewski, Thomas M.; Arnold, Ian M. F.; Momoli, Franco; Krewski, Daniel

    2016-01-01

    Aluminum (Al) is a ubiquitous substance encountered both naturally (as the third most abundant element) and intentionally (used in water, foods, pharmaceuticals, and vaccines); it is also present in ambient and occupational airborne particulates. Existing data underscore the importance of Al physical and chemical forms in relation to its uptake, accumulation, and systemic bioavailability. The present review represents a systematic examination of the peer-reviewed literature on the adverse health effects of Al materials published since a previous critical evaluation compiled by Krewski et al. (2007). Challenges encountered in carrying out the present review reflected the experimental use of different physical and chemical Al forms, different routes of administration, and different target organs in relation to the magnitude, frequency, and duration of exposure. Wide variations in diet can result in Al intakes that are often higher than the World Health Organization provisional tolerable weekly intake (PTWI), which is based on studies with Al citrate. Comparing daily dietary Al exposures on the basis of “total Al” assumes that gastrointestinal bioavailability for all dietary Al forms is equivalent to that for Al citrate, an approach that requires validation. Current occupational exposure limits (OELs) for identical Al substances vary as much as 15-fold. The toxicity of different Al forms depends in large measure on their physical behavior and relative solubility in water. The toxicity of soluble Al forms depends upon the delivered dose of Al+3 to target tissues. Trivalent Al reacts with water to produce bidentate superoxide coordination spheres [Al(O2)(H2O4)+2 and Al(H2O)6+3] that after complexation with O2•−, generate Al superoxides [Al(O2•)](H2O5)]+2. Semireduced AlO2• radicals deplete mitochondrial Fe and promote generation of H2O2, O2•− and OH•. Thus, it is the Al+3-induced formation of oxygen radicals that accounts for the oxidative damage that

  4. Systematic review of potential health risks posed by pharmaceutical, occupational and consumer exposures to metallic and nanoscale aluminum, aluminum oxides, aluminum hydroxide and its soluble salts.

    PubMed

    Willhite, Calvin C; Karyakina, Nataliya A; Yokel, Robert A; Yenugadhati, Nagarajkumar; Wisniewski, Thomas M; Arnold, Ian M F; Momoli, Franco; Krewski, Daniel

    2014-10-01

    oxidative damage that leads to intrinsic apoptosis. In contrast, the toxicity of the insoluble Al oxides depends primarily on their behavior as particulates. Aluminum has been held responsible for human morbidity and mortality, but there is no consistent and convincing evidence to associate the Al found in food and drinking water at the doses and chemical forms presently consumed by people living in North America and Western Europe with increased risk for Alzheimer's disease (AD). Neither is there clear evidence to show use of Al-containing underarm antiperspirants or cosmetics increases the risk of AD or breast cancer. Metallic Al, its oxides, and common Al salts have not been shown to be either genotoxic or carcinogenic. Aluminum exposures during neonatal and pediatric parenteral nutrition (PN) can impair bone mineralization and delay neurological development. Adverse effects to vaccines with Al adjuvants have occurred; however, recent controlled trials found that the immunologic response to certain vaccines with Al adjuvants was no greater, and in some cases less than, that after identical vaccination without Al adjuvants. The scientific literature on the adverse health effects of Al is extensive. Health risk assessments for Al must take into account individual co-factors (e.g., age, renal function, diet, gastric pH). Conclusions from the current review point to the need for refinement of the PTWI, reduction of Al contamination in PN solutions, justification for routine addition of Al to vaccines, and harmonization of OELs for Al substances.

  5. Surface treatment and analysis of aluminum alloy at room temperature with titanium-nitride films by dynamic mixing

    NASA Astrophysics Data System (ADS)

    Sato, T.; Ohata, K.; Fukushima, M.

    1988-06-01

    Titanium-nitride films were prepared on aluminum alloy (Al-11 wt.% Si) plates at room temperature by simultaneous ion bombardment and metal vapor deposition (dynamic mixing) using a high current ion source. The films were analysed by means of Auger electron spectroscopy and scanning electron microscopy. The results were compared with those made by metal vapor deposition and ion plating. The process of impurity inclusion in the titanium-nitride films made by dynamic mixing is discussed. Titanium films deposited by electron beam evaporation had high levels of oxygen impurities. However, when the same film was simultaneously bombarded by nitrogen ions, the levels of oxygen impurities decreased in the deposited titanium-nitride films.

  6. Single crystalline AlN film formed by direct nitridation of sapphire using aluminum oxynitride buffer

    NASA Astrophysics Data System (ADS)

    Nakao, Wataru; Fukuyama, Hiroyuki

    2003-12-01

    A noble method forming single crystalline AlN films has been developed as a new substrate for blue/UV light emitters. Sapphire substrates have been nitrided by appropriate CO-N 2 gas mixtures saturated with graphite based on the chemical potential diagram of the Al-N-O-C system. The nitrided surface of sapphire consists of consecutive layers of AlN and γ-aluminum oxynitride (γ-ALON) with low-level dislocation density, where the γ-ALON layer spontaneously forms as an equilibrium phase and acts as a buffer. The lattice mismatch between sapphire substrate and AlN layer has been effectively reduced by using the γ-ALON buffer, which significantly attributes to the growth of single crystalline AlN.

  7. The elastic-plastic response of aluminum films to ultrafast laser-generated shocks

    NASA Astrophysics Data System (ADS)

    Whitley, V. H.; McGrane, S. D.; Eakins, D. E.; Bolme, C. A.; Moore, D. S.; Bingert, J. F.

    2011-01-01

    We present the free surface response of 2, 5, and 8 μm aluminum films to shocks generated from chirped ultrafast lasers. We find two distinct steps to the measured free surface velocity that indicate a separation of the faster elastic wave from the slower plastic wave. We resolve the separation of the two waves to times as short as 20 ps. We measured peak elastic free surface velocities as high as 1.4 km/s corresponding to elastic stresses of 12 GPa. The elastic waves rapidly decay with increasing sample thickness. The magnitude of both the elastic wave and the plastic wave and the temporal separation between them was strongly dependent on the incident laser drive energy.

  8. Crystalline state and acoustic properties of zinc oxide films

    SciTech Connect

    Kal'naya, G.I.; Pryadko, I.F.; Yarovoi, Yu.A.

    1988-08-01

    We study the effect of the crystalline state of zinc oxide films, prepared by magnetron sputtering, on the efficiency of SAW transducers based on the layered system textured ZnO film-interdigital transducer (IDT)-fused quartz substrate. The crystalline perfection of the ZnO films was studied by the x-ray method using a DRON-2.0 diffractometer. The acoustic properties of the layered system fused quartz substrate-IDT-zinc oxide film were evaluated based on the squared electromechanical coupling constant K/sup 2/ for strip filters. It was found that K/sup 2/ depends on the magnitude of the mechanical stresses. When zinc oxide films are deposited by the method of magnetron deposition on fused quartz substrates, depending on the process conditions limitations can arise on the rate of deposition owing to mechanical stresses, which significantly degrade the efficiency of SAW transducers based on them, in the ZnO films.

  9. Amorphous tin-cadmium oxide films and the production thereof

    SciTech Connect

    Li, Xiaonan; Gessert, Timothy A

    2013-10-29

    A tin-cadmium oxide film having an amorphous structure and a ratio of tin atoms to cadmium atoms of between 1:1 and 3:1. The tin-cadmium oxide film may have an optical band gap of between 2.7 eV and 3.35 eV. The film may also have a charge carrier concentration of between 1.times.10.sup.20 cm.sup.-3 and 2.times.10.sup.20 cm.sup.-3. The tin cadmium oxide film may also exhibit a Hall mobility of between 40 cm.sup.2V.sup.-1 s.sup.-1 and 60 cm.sup.2V.sup.-1 s.sup.-1. Also disclosed is a method of producing an amorphous tin-cadmium oxide film as described and devices using same.

  10. Double-layer anti-reflection coating containing a nanoporous anodic aluminum oxide layer for GaAs solar cells.

    PubMed

    Yang, Tianshu; Wang, Xiaodong; Liu, Wen; Shi, Yanpeng; Yang, Fuhua

    2013-07-29

    Multilayer anti-reflection (AR) coatings can be used to improve the efficiency of Gallium Arsenide (GaAs) solar cells. We propose an alternate method to obtain optical thin films with specified refractive indices, which is using a self-assembled nanoporous anodic aluminum oxide (AAO) template as an optical thin film whose effective refractive index can be tuned by pore-widening. Different kinds of double-layer AR coatings each containing an AAO layer were designed and investigated by finite difference time domain (FDTD) method. We demonstrate that a λ /4n - λ /4n AR coating consisting of a TiO(2) layer and an AAO layer whose effective refractive index is 1.32 realizes a 96.8% light absorption efficiency of the GaAs solar cell under AM1.5 solar spectrum (400 nm-860 nm). We also have concluded some design principles of the double-layer AR coating containing an AAO layer for GaAs solar cells.

  11. Ultrasonic Spray-Assisted Solution-Based Vapor-Deposition of Aluminum Tris(8-hydroxyquinoline) Thin Films

    NASA Astrophysics Data System (ADS)

    Piao, Jinchun; Katori, Shigetaka; Ikenoue, Takumi; Fujita, Shizuo

    2011-02-01

    Aluminum tris(8-hydroxyquinoline) (Alq3) thin films were fabricated by a vapor-deposition technique from its methanol solution, that is, by the ultrasonic-assisted mist deposition technique. The application of high ultrasonic power to the Alq3-methanol mixture resulted in a stable and transparent solution. Mist particles formed by ultrasonic atomization of the solution were used as the source for vapor-deposition at the substrate temperature of 100-200 °C. Optical absorption and photoluminescence characteristics indicated the formation of Alq3 thin films. The results promise the formation of thin films of a variety of organic materials by the solution-based technique.

  12. High transmission and low color cross-talk plasmonic color filters using triangular-lattice hole arrays in aluminum films.

    PubMed

    Chen, Qin; Cumming, David R S

    2010-06-21

    Three primary color (red, green and blue) filters consisting of subwavelength triangular-lattice hole arrays in an aluminum film on glass were simulated and fabricated. A silicon dioxide cap layer, deposited on the patterned aluminum film, was found to almost double the transmission efficiency for all the filters. The measured peak transmittance for each color filter was above 30%, exhibiting a wavelength spectrum with a full-width at half-maximum of approximately 100 nm. Simulation results of various structures with different cap layers revealed the enhanced coupling between surface plasmon resonances at both sides of the metal film in a symmetrical configuration. It was found that gratings with as few as three periods were sufficient to demonstrate filtering. The effect of metal thickness and hole size was investigated in detail.

  13. Interactions of aluminum with biochars and oxidized biochars: implications for the biochar aging process.

    PubMed

    Qian, Linbo; Chen, Baoliang

    2014-01-15

    Interactions of aluminum with primary and oxidized biochars were compared to understand the changes in the adsorption properties of aged biochars. The structural characteristics of rice straw-derived biochars, before and after oxidation by HNO3/H2SO4, were analyzed by element composition, FTIR, and XPS. The adsorption of Al to primary biochars was dominated by binding to inorganic components (such as silicon particles) and surface complexation of oxygen-containing functional groups via esterification reactions. Oxidization (aging) introduced carboxylic functional groups on biochar surfaces, which served as additional binding sites for Al(3+). At pH 2.5-3.5, the Al(3+) binding was significantly greater on oxidized biochars than primary biochars. After loading with Al, the -COOH groups anchored to biochar surfaces were transformed into COO(-) groups, and the negative surface charge diminished, which indicated that Al(3+) coordinated with COO(-). Biochar is suggested as a potential adsorbent for removing Al from acidic soils.

  14. Application of diffusion barriers to the refractory fibers of tungsten, columbium, carbon and aluminum oxide

    NASA Technical Reports Server (NTRS)

    Douglas, F. C.; Paradis, E. L.; Veltri, R. D.

    1973-01-01

    A radio frequency powered ion-plating system was used to plate protective layers of refractory oxides and carbide onto high strength fiber substrates. Subsequent overplating of these combinations with nickel and titanium was made to determine the effectiveness of such barrier layers in preventing diffusion of the overcoat metal into the fibers with consequent loss of fiber strength. Four substrates, five coatings, and two metal matrix materials were employed for a total of forty material combinations. The substrates were tungsten, niobium, NASA-Hough carbon, and Tyco sapphire. The diffusion-barrier coatings were aluminum oxide, yttrium oxide, titanium carbide, tungsten carbide with 14% cobalt addition, and zirconium carbide. The metal matrix materials were IN 600 nickel and Ti 6/4 titanium. Adhesion of the coatings to all substrates was good except for the NASA-Hough carbon, where flaking off of the oxide coatings in particular was observed.

  15. Preparation of Nickel-Aluminum-Containing Layered Double Hydroxide Films by Secondary (Seeded) Growth Method and Their Electrochemical Properties.

    PubMed

    Zhang, Fazhi; Guo, Li; Xu, Sailong; Zhang, Rong

    2015-06-23

    Thin films of nickel-aluminum-containing layered double hydroxide (NiAl-LDH) have been prepared on nickel foil and nickel foam substrates by secondary (seeded) growth of NiAl-LDH seed layer. The preparation procedure consists of deposition of LDH seeds from a colloidal suspension on the substrate by dip coating, followed by hydrothermal treatment of the nanocrystals to form the LDH film. The secondary grown film is found to provide a higher crystallinity and more uniform composition of metal cations in the film layer than the in situ grown film on seed-free substrate under identical hydrothermal conditions. A systematic investigation of the film evolution process reveals that the crystallite growth rate is relatively fast for the secondary grown film because of the presence of LDH nanocrystal seeds. Electrochemical performance of the resulting NiAl-LDH films as positive electrode material was further assessed as an example of their practical applications. The secondary grown film electrode delivers improved recharge-discharge capacity and cycling stability compared with that of the in situ grown film, which can be explained by the existence of a unique microstructure of the former. Our findings show an example for the effective fabrication of LDH film with controllable microstructure and enhanced application performance through a secondary (seeded) growth procedure.

  16. Active Oxygen Generator by Silent Discharge and Oxidation Power in Formation of Oxide Thin Films

    NASA Astrophysics Data System (ADS)

    Tanaka, Masaaki; Kawagoe, Yasuyuki; Tsukazaki, Hisashi; Yamanishi, Kenichiro

    We have studied the low pressure silent discharge type active oxygen generator in terms of the application to the formation of oxide thin films. In this paper the oxidation power of active oxygen in the oxide thin film formation is compared with that of oxygen and ozone by forming silicon oxide thin films. It was confirmed that the oxidation power is in turn of active oxygen > ozone > oxygen from the experimental result of the number of x in SiOx thin film. Furthermore we applied active oxygen to the formation of the thin film high temperature super conductor and active oxygen was found to be effective to the formation of the thin film with high performance.

  17. Adsorption and adsolubilization of polymerizable surfactants on aluminum oxide.

    PubMed

    Attaphong, Chodchanok; Asnachinda, Emma; Charoensaeng, Ampira; Sabatini, David A; Khaodhiar, Sutha

    2010-04-01

    Surfactant-based adsorption processes have been widely investigated for environmental applications. A major problem facing surfactant-modified adsorbents is surfactant loss from the adsorbent due to loss of monomers from solution and subsequent surfactant desorption. For this study, a bilayer of anionic polymerizable surfactant (Hitenol BC 05, Hitenol BC 10 and Hitenol BC 20) and non-polymerizable surfactant (Hitenol N 08) was adsorbed onto alumina. The results of adsorption studies showed that as the number of ethylene oxide (EO) groups of the surfactants increased, the area per molecule increased and the maximum adsorption decreased. The lowest maximum adsorption onto alumina was for Hitenol BC 20 (20 EO groups) corresponding to 0.08 mmol/g or 0.34 molecule/nm(2) while the highest level of adsorption was 0.30 mmol/g or 1.28 molecule/nm(2) for Hitenol BC 05 (5 EO groups). This variation in adsorption was attributed to the increased bulkiness of the head group with increasing number of EO groups. Relative to the adsolubilization capacity of organic solutes, ethylcyclohexane adsolubilizes more than styrene. Styrene and ethylcyclohexane adsolubilization were both independent of the number of EO groups of the surfactant. For surfactant desorption studies, the polymerization of polymerizable surfactants increased the stability of surfactants adsorbed onto the alumina surface and reduced surfactant desorption from the alumina surface. These results provide useful information on surfactant-based surface modification to enhance contaminant remediation and industrial applications.

  18. Auger electron spectroscopy study of initial stages of oxidation in a copper - 19.6-atomic-percent-aluminum alloy

    NASA Technical Reports Server (NTRS)

    Ferrante, J.

    1973-01-01

    Auger electron spectroscopy was used to examine the initial stages of oxidation of a polycrystalline copper - 19.6 a/o-aluminum alloy. The growth of the 55-eV aluminum oxide peak and the decay of the 59-, 62-, and 937-eV copper peaks were examined as functions of temperature, exposure, and pressure. Pressures ranged from 1x10 to the minus 7th power to 0.0005 torr of O2. Temperatures ranged from room temperature to 700 C. A completely aluminum oxide surface layer was obtained in all cases. Complete disappearance of the underlying 937-eV copper peak was obtained by heating at 700 C in O2 at 0.0005 torr for 1 hr. Temperature studies indicated that thermally activated diffusion was important to the oxidation studies. The initial stages of oxidation followed a logarithmic growth curve.

  19. Diffusion-reaction of aluminum and oxygen in thermally grown Al2O3 oxide layers

    NASA Astrophysics Data System (ADS)

    Osorio, Julián D.; Giraldo, Juliana; Hernández, Juan C.; Toro, Alejandro; Hernández-Ortiz, Juan P.

    2014-04-01

    The diffusion-reaction of aluminum (Al) and oxygen (O), to form thermally grown oxide (TGO) layers in thermal barrier coatings (TBCs), is studied through an analytical model. A nonsymmetrical radial basis function approach is used to numerically solve the mass balance equations that predict the TGO growth. Correct boundary conditions for the Al and O reactions are laid out using scaling arguments. The Damköhler number shows that the O-Al reaction is several orders of magnitude faster than diffusion. In addition, a comparison between aluminum and oxygen diffusivities indicates that TGO growth is governed by aluminum diffusion. The results are compared with experimental measurements on air plasma spray-deposited TBCs treated at 1,373 K with exposure times ranging from 1 to 1700 hours. We found that, for several time decades, the thickness of the thermally grown layer has power law dependence of time with an exponent of ½, following the diffusion control mechanism. At later times, however, the presence of other oxides and additional kinetics modify the diffusive exponent.

  20. Effects of advanced oxidation pretreatment on residual aluminum control in high humic acid water purification.

    PubMed

    Wang, Wendong; Li, Hua; Ding, Zhenzhen; Wang, Xiaochang

    2011-01-01

    Due to the formation of disinfection by-products and high concentrations of Al residue in drinking water purification, humic substances are a major component of organic matter in natural waters and have therefore received a great deal of attention in recent years. We investigated the effects of advanced oxidation pretreatment methods usually applied for removing dissolved organic matters on residual Al control. Results showed that the presence of humic acid increased residual Al concentration notably. With 15 mg/L of humic acid in raw water, the concentrations of soluble aluminum and total aluminum in the treated water were close to the quantity of Al addition. After increasing coagulant dosage from 12 to 120 mg/L, the total-Al in the treated water was controlled to below 0.2 mg/L. Purification systems with ozonation, chlorination, or potassium permanganate oxidation pretreatment units had little effects on residual Al control; while UV radiation decreased Al concentration notably. Combined with ozonation, the effects of UV radiation were enhanced. Optimal dosages were 0.5 mg O3/mg C and 3 hr for raw water with 15 mg/L of humic acid. Under UV light radiation, the combined forces or bonds that existed among humic acid molecules were destroyed; adsorption sites increased positively with radiation time, which promoted adsorption of humic acid onto polymeric aluminum and Al(OH)3(s). This work provides a new solution for humic acid coagulation and residual Al control for raw water with humic acid purification.

  1. Visible light-induced photocatalytic reduction of graphene oxide by tungsten oxide thin films

    NASA Astrophysics Data System (ADS)

    Choobtashani, M.; Akhavan, O.

    2013-07-01

    Tungsten oxide thin films (deposited by thermal evaporation or sol gel method) were used for photocatalytic reduction of graphene oxide (GO) platelets (synthesized through a chemical exfoliation method) on surface of the films under UV or visible light of the environment, in the absence of any aqueous ambient at room temperature. Atomic force microscopy (AFM) technique was employed to characterize surface morphology of the GO sheets and the tungsten oxide films. Moreover, using X-ray photoelectron spectroscopy (XPS), chemical state of the tungsten oxide films and the photocatalytic reduction of the GO platelets were quantitatively investigated. The better performance of the sol-gel tungsten oxide films in photocatalytic reduction of GO platelets as compared to the evaporated tungsten oxide films was assigned to lower W5+/W6+ ratio (i.e., a better stoichiometry) and higher surface water content of the sol-gel film. The GO reduction level achieved after 24 h UV-assisted photocatalytic reduction on surface of the sol-gel tungsten oxide film was comparable with the reduction level usually obtainable by hydrazine. The sol-gel tungsten oxide film even showed an efficient photocatalytic reduction of the GO platelets after exposure to the visible light of the environment for 2 days.

  2. Crystal structure of complex natural aluminum magnesium calcium iron oxide

    SciTech Connect

    Rastsvetaeva, R. K. Aksenov, S. M.; Verin, I. A.

    2010-07-15

    The structure of a new natural oxide found near the Tashelga River (Eastern Siberia) was studied by X-ray diffraction. The pseudo-orthorhombic unit cell parameters are a = 5.6973(1) A, b = 17.1823(4) A, c = 23.5718(5) A, {beta} = 90{sup o}, sp. gr. Pc. The structure was refined to R = 0.0516 based on 4773 reflections with vertical bar F vertical bar > 7{sigma}(F) taking into account the twin plane perpendicular to the z axis (the twin components are 0.47 and 0.53). The crystal-chemical formula (Z = 4) is Ca{sub 2}Mg{sub 2}{sup IV}Fe{sub 2}{sup (2+)IV}[Al{sub 14}{sup VI}O{sub 31}(OH)][Al{sub 2}{sup IV}O][Al{sup IV}]AL{sup IV}(OH)], where the Roman numerals designate the coordination of the atoms. The structure of the mineral is based on wide ribbons of edge-sharing Al octahedra (an integral part of the spinel layer). The ribbons run along the shortest x axis and are inclined to the y and z axes. The adjacent ribbons are shifted with respect to each other along the y axis, resulting in the formation of step-like layers in which the two-ribbon thickness alternates with the three-ribbon thickness. Additional Al octahedra and Mg and Fe{sup 2+} tetrahedra are located between the ribbons. The layers are linked together to form a three-dimensional framework by Al tetrahedra, Ca polyhedra, and hydrogen bonds with the participation of OH groups.

  3. Films based on oxidized starch and cellulose from barley.

    PubMed

    El Halal, Shanise Lisie Mello; Colussi, Rosana; Deon, Vinícius Gonçalves; Pinto, Vânia Zanella; Villanova, Franciene Almeida; Carreño, Neftali Lenin Villarreal; Dias, Alvaro Renato Guerra; Zavareze, Elessandra da Rosa

    2015-11-20

    Starch and cellulose fibers were isolated from grains and the husk from barley, respectively. Biodegradable films of native starch or oxidized starches and glycerol with different concentrations of cellulose fibers (0%, 10% and 20%) were prepared. The films were characterized by morphological, mechanical, barrier, and thermal properties. Cellulose fibers isolated from the barley husk were obtained with 75% purity and high crystallinity. The morphology of the films of the oxidized starches, regardless of the fiber addition, was more homogeneous as compared to the film of the native starch. The addition of cellulose fibers in the films increased the tensile strength and decreased elongation. The water vapor permeability of the film of oxidized starch with 20% of cellulose fibers was lower than the without fibers. However the films with cellulose fibers had the highest decomposition with the initial temperature and thermal stability. The oxidized starch and cellulose fibers from barley have a good potential for use in packaging. The addition of cellulose fibers in starch films can contribute to the development of films more resistant that can be applied in food systems to maintain its integrity.

  4. The Cryogenic Properties of Several Aluminum-Beryllium Alloys and a Beryllium Oxide Material

    NASA Technical Reports Server (NTRS)

    Gamwell, Wayne R.; McGill, Preston B.

    2003-01-01

    Performance related mechanical properties for two aluminum-beryllium (Al-Be) alloys and one beryllium-oxide (BeO) material were developed at cryogenic temperatures. Basic mechanical properties (Le., ultimate tensile strength, yield strength, percent elongation, and elastic modulus were obtained for the aluminum-beryllium alloy, AlBeMetl62 at cryogenic [-195.5"C (-320 F) and -252.8"C (-423"F)I temperatures. Basic mechanical properties for the Be0 material were obtained at cyrogenic [- 252.8"C (-423"F)] temperatures. Fracture properties were obtained for the investment cast alloy Beralcast 363 at cryogenic [-252.8"C (-423"F)] temperatures. The AlBeMetl62 material was extruded, the Be0 material was hot isostatic pressing (HIP) consolidated, and the Beralcast 363 material was investment cast.

  5. Where bio meets nano: the many uses for nanoporous aluminum oxide in biotechnology.

    PubMed

    Ingham, Colin J; ter Maat, Jurjen; de Vos, Willem M

    2012-01-01

    Porous aluminum oxide (PAO) is a ceramic formed by an anodization process of pure aluminum that enables the controllable assembly of exceptionally dense and regular nanopores in a planar membrane. As a consequence, PAO has a high porosity, nanopores with high aspect ratio, biocompatibility and the potential for high sensitivity imaging and diverse surface modifications. These properties have made this unusual material attractive to a disparate set of applications. This review examines how the structure and properties of PAO connect with its present and potential uses within research and biotechnology. The role of PAO is covered in areas including microbiology, mammalian cell culture, sensitive detection methods, microarrays and other molecular assays, and in creating new nanostructures with further uses within biology.

  6. Surface reaction mechanisms during ozone and oxygen plasma assisted atomic layer deposition of aluminum oxide.

    PubMed

    Rai, Vikrant R; Vandalon, Vincent; Agarwal, Sumit

    2010-09-07

    We have elucidated the reaction mechanism and the role of the reactive intermediates in the atomic layer deposition (ALD) of aluminum oxide from trimethyl aluminum in conjunction with O(3) and an O(2) plasma. In situ attenuated total reflection Fourier transform infrared spectroscopy data show that both -OH groups and carbonates are formed on the surface during the oxidation cycle. These carbonates, once formed on the surface, are stable to prolonged O(3) exposure in the same cycle. However, in the case of plasma-assisted ALD, the carbonates decompose upon prolonged O(2) plasma exposure via a series reaction kinetics of the type, A (CH(3)) --> B (carbonates) --> C (Al(2)O(3)). The ratio of -OH groups to carbonates on the surface strongly depends on the oxidizing agent, and also the duration of the oxidation cycle in plasma-assisted ALD. However, in both O(3) and O(2) plasma cycles, carbonates are a small fraction of the total number of reactive sites compared to the hydroxyl groups.

  7. A thin-film aluminum strain gauges array in a flexible gastrointestinal catheter for pressure measurements

    NASA Astrophysics Data System (ADS)

    Sousa, P. J.; Silva, L. R.; Pinto, V. C.; Goncalves, L. M.; Minas, G.

    2016-08-01

    This paper presents an innovative approach to measure the pressure patterns associated with the motility and peristaltic movements in the upper gastrointestinal tract. This approach is based on inexpensive and easy to fabricate thin-film aluminum strain gauge pressure sensors using a flexible polyimide film (Kapton) as substrate and SU-8 structural support. These sensors are fabricated using well-established and standard photolithographic and wet etching techniques. Each sensor has a 3.4 mm2 area, allowing a fabrication process with a high level of sensors integration (four sensors in 1.7 cm), which is suitable for placing them in a single catheter. These strain gauges bend when pressure is applied and, consequently, their electrical resistance is changed. The fabricated sensors feature an almost linear response (R 2  =  0.9945) and an overall sensitivity of 6.4 mV mmHg-1. Their readout and control electronics were developed in a flexible Kapton ribbon cable and, together with the sensors, bonded and wrapped around a catheter-like structure. The sequential acquisition of the different signals is carried by a microcontroller with a 10 bit ADC at a sample rate of 250 Hz per-1 sensor. The signals are presented in a user friendly interface developed using the integrated development environment software, QtCreator IDE, for better visualization by physicians.

  8. Template synthesis and characterization of nanostructured lithium insertion electrodes and nanogold/porous aluminum oxide composite membranes

    NASA Astrophysics Data System (ADS)

    Patrissi, Charles John

    A membrane-based template synthesis method was used to prepare nanostructured Li-ion battery electrodes and nanogold/porous aluminum oxide composite membranes. Membrane-based template synthesis is a general method for the preparation of nanomaterials which entails deposition of the material of interest, or a suitable precursor, within the nanometer-diameter pores in a porous template membrane. This method allows for control of nanoparticle size and shape and is compatible with many methods of synthesis for bulk materials. The template membranes used in this work were commercially available porous polycarbonate filtration membranes and nanoporous aluminum oxide membranes that were prepared in-house. Nanostructured electrodes of orthorhombic V2O5, prepared using membrane-based template synthesis, were used to investigate the effects of Li-ion diffusion distance and V2O5 surface area on electrode rate capability. Nanowires of V2O5 were prepared by depositing a precursor in the pores of microporous polycarbonate filtration membranes. The result was an ensemble of 115 nm diameter, 2 mum long nanowires of V2O5 which protruded from a V 2O5 surface layer like the bristles of a brush. The Li + storage capacity of the nanostructured electrode was compared to a thin film control electrode at high discharge rates. Results show that the nanostructured electrode delivered three to four times the capacity of the thin film electrode at discharge rates above 500 C. A membrane based template synthesis method was also used to prepare crystalline V2O5 electrodes which have high volumetric charge capacities, at high discharge rates, compared to a thin-film control electrode. In order to obtain high volumetric rate capability, the as-received polycarbonate template membranes were chemically etched to increase membrane porosity. Nanofibrous electrodes of crystalline V2O5 were then prepared by depositing an alkoxide precursor in the pores of the etched membranes. Electrode volumetric

  9. Assessing the fate and effects of nano aluminum oxide in the terrestrial earthworm, Eisenia fetida.

    PubMed

    Coleman, Jessica G; Johnson, David R; Stanley, Jacob K; Bednar, Anthony J; Weiss, Charles A; Boyd, Robert E; Steevens, Jeffery A

    2010-07-01

    Nano-sized aluminum is currently being used by the military and commercial industries in many applications including coatings, thermites, and propellants. Due to the potential for wide dispersal in soil systems, we chose to investigate the fate and effects of nano-sized aluminum oxide (Al2O3), the oxidized form of nano aluminum, in a terrestrial organism. The toxicity and bioaccumulation potential of micron-sized (50-200 microm, nominal) and nano-sized (11 nm, nominal) Al2O3 was comparatively assessed through acute and subchronic bioassays using the terrestrial earthworm, Eisenia fetida. Subchronic (28-d) studies were performed exposing E. fetida to nano- and micron-sized Al2O3-spiked soils to assess the effects of long-term exposure. No mortality occurred in subchronic exposures, although reproduction decreased at >or=3,000 mg/kg nano-sized Al2O3 treatments, with higher aluminum body burdens observed at 100 and 300 mg/kg; no reproductive effects were observed in the micron-sized Al2O3 treatments. In addition to toxicity and bioaccumulation bioassays, an acute (48-h) behavioral bioassay was conducted utilizing a soil avoidance wheel in which E. fetida were given a choice of habitat between control, nano-, or micron-sized Al2O3 amended soils. In the soil avoidance bioassays, E. fetida exhibited avoidance behavior toward the highest concentrations of micron- and nano-sized Al2O3 (>5,000 mg/kg) relative to control soils. Results of the present study indicate that nano-sized Al2O3 may impact reproduction and behavior of E. fetida, although at high levels unlikely to be found in the environment.

  10. Aerosol chemical vapor deposition of metal oxide films

    DOEpatents

    Ott, Kevin C.; Kodas, Toivo T.

    1994-01-01

    A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said FIELD OF THE INVENTION The present invention relates to the field of film coating deposition techniques, and more particularly to the deposition of multicomponent metal oxide films by aerosol chemical vapor deposition. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

  11. Growth of porous anodized alumina on the sputtered aluminum films with 2D-3D morphology for high specific surface area

    NASA Astrophysics Data System (ADS)

    Liao, M. W.; Chung, C. K.

    2014-08-01

    The porous anodic aluminum oxide (AAO) with high-aspect-ratio pore channels is widely used as a template for fabricating nanowires or other one-dimensional (1D) nanostructures. The high specific surface area of AAO can also be applied to the super capacitor and the supporting substrate for catalysis. The rough surface could be helpful to enhance specific surface area but it generally results in electrical field concentration even to ruin AAO. In this article, the aluminum (Al) films with the varied 2D-3D morphology on Si substrates were prepared using magnetron sputtering at a power of 50 W-185 W for 1 h at a working pressure of 2.5 × 10-1 Pa. Then, AAO was fabricated from the different Al films by means of one-step hybrid pulse anodizing (HPA) between the positive 40 V and the negative -2 V (1 s:1 s) for 3 min in 0.3 M oxalic acid at a room temperature. The microstructure and morphology of Al films were characterized by X-ray diffraction, scanning electron microscope and atomic force microscope, respectively. Some hillocks formed at the high target power could be attributed to the grain texture growth in the normal orientation of Al(1 1 1). The 3D porous AAO structure which is different from the conventional 2D planar one has been successfully demonstrated using HPA on the film with greatly rough hillock-surface formed at the highest power of 185 W. It offers a potential application of the new 3D AAO to high specific surface area devices.

  12. Ballistic phonon and thermal radiation transport across a minute vacuum gap in between aluminum and silicon thin films: Effect of laser repetitive pulses on transport characteristics

    NASA Astrophysics Data System (ADS)

    Yilbas, B. S.; Ali, H.

    2016-08-01

    Short-pulse laser heating of aluminum and silicon thin films pair with presence of a minute vacuum gap in between them is considered and energy transfer across the thin films pair is predicted. The frequency dependent Boltzmann equation is used to predict the phonon intensity distribution along the films pair for three cycles of the repetitive short-pulse laser irradiation on the aluminum film surface. Since the gap size considered is within the Casimir limit, thermal radiation and ballistic phonon contributions to energy transfer across the vacuum gap is incorporated. The laser irradiated field is formulated in line with the Lambert's Beer law and it is considered as the volumetric source in the governing equations of energy transport. In order to assess the phonon intensity distribution in the films pair, equivalent equilibrium temperature is introduced. It is demonstrated that thermal separation of electron and lattice sub-systems in the aluminum film, due to the short-pulse laser irradiation, takes place and electron temperature remains high in the aluminum film while equivalent equilibrium temperature for phonons decays sharply in the close region of the aluminum film interface. This behavior is attributed to the phonon boundary scattering at the interface and the ballistic phonon transfer to the silicon film across the vacuum gap. Energy transfer due to the ballistic phonon contribution is significantly higher than that of the thermal radiation across the vacuum gap.

  13. Determining the Effect of Aluminum Oxide Nanoparticles on the Aggregation of Amyloid-Beta in Transgenic Caenorhabditis elegans

    NASA Astrophysics Data System (ADS)

    Patel, Suhag; Matticks, John; Howell, Carina

    2014-03-01

    The cause of Alzheimer's disease has been linked partially to genetic factors but the predicted environmental components have yet to be determined. In Alzheimer's, accumulation of amyloid-beta protein in the brain forms plaques resulting in neurodegeneration and loss of mental functions. It has been postulated that aluminum influences the aggregation of amyloid-beta. To test this hypothesis, transgenic Caenorhabditis elegans, CL2120, was used as a model organism to observe neurodegeneration in nematodes exposed to aluminum oxide nanoparticles. Behavioral testing, fluorescent staining, and fluorescence microscopy were used to test the effects of aggregation of amyloid-beta in the nervous systems of effected nematodes exposed to aluminum oxide nanoparticles. Energy-dispersive x-ray spectroscopy was used to quantify the total concentration of aluminum oxide that the worms were exposed to during the experiment. Exposure of transgenic and wild type worms to a concentration of 4 mg mL-1 aluminum oxide showed a decrease in the sinusoidal motion, as well as an infirmity of transgenic worms when compared to control worms. These results support the hypothesis that aluminum may play a role in neurodegeneration in C. elegans, and may influence and increase the progression of Alzheimer's disease. This work was supported by National Science Foundation grants DUE-1058829, DMR-0923047 DUE-0806660 and Lock Haven FPDC grants.

  14. Nanoporous anodic aluminum oxide with a long-range order and tunable cell sizes by phosphoric acid anodization on pre-patterned substrates.

    PubMed

    Surawathanawises, Krissada; Cheng, Xuanhong

    2014-01-20

    Nanoporous anodic aluminum oxide (AAO) has been explored for various applications due to its regular cell arrangement and relatively easy fabrication processes. However, conventional two-step anodization based on self-organization only allows the fabrication of a few discrete cell sizes and formation of small domains of hexagonally packed pores. Recent efforts to pre-pattern aluminum followed with anodization significantly improve the regularity and available pore geometries in AAO, while systematic study of the anodization condition, especially the impact of acid composition on pore formation guided by nanoindentation is still lacking. In this work, we pre-patterned aluminium thin films using ordered monolayers of silica beads and formed porous AAO in a single-step anodization in phosphoric acid. Controllable cell sizes ranging from 280 nm to 760 nm were obtained, matching the diameters of the silica nanobead molds used. This range of cell size is significantly greater than what has been reported for AAO formed in phosphoric acid in the literature. In addition, the relationships between the acid concentration, cell size, pore size, anodization voltage and film growth rate were studied quantitatively. The results are consistent with the theory of oxide formation through an electrochemical reaction. Not only does this study provide useful operational conditions of nanoindentation induced anodization in phosphoric acid, it also generates significant information for fundamental understanding of AAO formation.

  15. Altering properties of cerium oxide thin films by Rh doping

    SciTech Connect

    Ševčíková, Klára; Nehasil, Václav; Vorokhta, Mykhailo; Haviar, Stanislav; Matolín, Vladimír; and others

    2015-07-15

    Highlights: • Thin films of ceria doped by rhodium deposited by RF magnetron sputtering. • Concentration of rhodium has great impact on properties of Rh–CeO{sub x} thin films. • Intensive oxygen migration in films with low concentration of rhodium. • Oxygen migration suppressed in films with high amount of Rh dopants. - Abstract: Ceria containing highly dispersed ions of rhodium is a promising material for catalytic applications. The Rh–CeO{sub x} thin films with different concentrations of rhodium were deposited by RF magnetron sputtering and were studied by soft and hard X-ray photoelectron spectroscopies, Temperature programmed reaction and X-ray powder diffraction techniques. The sputtered films consist of rhodium–cerium mixed oxide where cerium exhibits a mixed valency of Ce{sup 4+} and Ce{sup 3+} and rhodium occurs in two oxidation states, Rh{sup 3+} and Rh{sup n+}. We show that the concentration of rhodium has a great influence on the chemical composition, structure and reducibility of the Rh–CeO{sub x} thin films. The films with low concentrations of rhodium are polycrystalline, while the films with higher amount of Rh dopants are amorphous. The morphology of the films strongly influences the mobility of oxygen in the material. Therefore, varying the concentration of rhodium in Rh–CeO{sub x} thin films leads to preparing materials with different properties.

  16. Coprecipitation of arsenate with metal oxides: nature, mineralogy, and reactivity of aluminum precipitates.

    PubMed

    Violante, Antonio; Ricciardella, Mariarosaria; Del Gaudio, Stefania; Pigna, Massimo

    2006-08-15

    Arsenic mobilization in soils is mainly controlled by sorption/desorption processes, but arsenic also may be coprecipitated with aluminum and/or iron in natural environments. Although coprecipitation of arsenic with aluminum and iron oxides is an effective treatment process for arsenic removal from drinking water, the nature and reactivity of aluminum- or iron-arsenic coprecipitates has received little attention. We studied the mineralogy, chemical composition, and surface properties of aluminum-arsenate coprecipitates, as well as the sorption of phosphate on and the loss of arsenate from these precipitates. Aluminum-arsenate coprecipitates were synthesized at pH 4.0, 7.0, or 10.0 and As/Al molar ratio (R) of 0, 0.01, or 0.1 and were aged 30 or 210 d at 50 degrees C. In the absence of arsenate, gibbsite (pH 4.0 or 7.0) and bayerite (pH 10.0) formed, whereas in the presence of arsenate, very poorly crystalline precipitates formed. Short-range ordered materials (mainly poorly crystalline boehmite) formed at pH 4.0 (R = 0.01 and 0.1), 7.0, and 10.0 (R= 0.1) and did not transform into Al(OH)3 polymorphs even after prolonged aging. The surface properties and chemical composition of the aluminum precipitates were affected by the initial pH, R, and aging. Chemical dissolution of the samples by 6 mol L(-1) HCl and 0.2 mol L(-1) oxalic acid/ oxalate solution indicated that arsenate was present mainly in the short-range ordered precipitates. The sorption of phosphate onto the precipitates was influenced by the nature of the samples and the amounts of arsenate present in the precipitates. Large amounts of phosphate partially replaced arsenate only from the samples formed at R = 0.1. The quantities of arsenate desorbed from these coprecipitates by phosphate increased with increasing phosphate concentration, reaction time, and precipitate age butwere always lessthan 30% of the amounts of arsenate present in the materials and were particularly low (<4%) from the sample prepared

  17. Method for producing high quality oxide films on substrates

    DOEpatents

    Ruckman, M.W.; Strongin, M.; Gao, Y.L.

    1993-11-23

    A method is described for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material. 4 figures.

  18. Method for producing high quality oxide films on substrates

    DOEpatents

    Ruckman, Mark W.; Strongin, Myron; Gao, Yong L.

    1993-01-01

    A method for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material.

  19. Aluminum nitride thin film based acoustic wave sensors for biosensing applications

    NASA Astrophysics Data System (ADS)

    Xu, Jianzeng

    monitoring the frequency and phase changes in response to the coating of aluminum thin films onto the device surface. The derived mass sensitivity indicates that both modes could potentially reach an extremely low detection limit at the level of picograms.

  20. Removal of hydrogen chloride from gaseous streams using magnesium-aluminum oxide.

    PubMed

    Kameda, Tomohito; Uchiyama, Naoya; Park, Kye-Sung; Grause, Guido; Yoshioka, Toshiaki

    2008-10-01

    Magnesium-aluminum oxide (Mg-Al oxide) obtained by thermal decomposition of Mg-Al layered double hydroxide (Mg-Al LDH) effectively removed HCl from gaseous streams. HCl removal was greater in the presence of added water vapor at all temperatures examined and increased with decreasing temperature in both the presence and absence of added water vapor. Wet and dry removal of gaseous HCl were attributed to the production of MgCl2 . 6H2O and MgCl2 . 4H2O, respectively. For the wet scrubbing process, the reconstruction reaction of Mg-Al LDH from Mg-Al oxide was the primary mechanism for increased HCl removal.

  1. Lateral solid-phase epitaxy of oxide thin films on glass substrate seeded with oxide nanosheets.

    PubMed

    Taira, Kenji; Hirose, Yasushi; Nakao, Shoichiro; Yamada, Naoomi; Kogure, Toshihiro; Shibata, Tatsuo; Sasaki, Takayoshi; Hasegawa, Tetsuya

    2014-06-24

    We developed a technique to fabricate oxide thin films with uniaxially controlled crystallographic orientation and lateral size of more than micrometers on amorphous substrates. This technique is lateral solid-phase epitaxy, where epitaxial crystallization of amorphous precursor is seeded with ultrathin oxide nanosheets sparsely (≈10% coverage) deposited on the substrate. Transparent conducting Nb-doped anatase TiO2 thin films were fabricated on glass substrates by this technique. Perfect (001) orientation and large grains with lateral sizes up to 10 μm were confirmed by X-ray diffraction, atomic force microscopy, and electron beam backscattering diffraction measurements. As a consequence of these features, the obtained film exhibited excellent electrical transport properties comparable to those of epitaxial thin films on single-crystalline substrates. This technique is a versatile method for fabricating high-quality oxide thin films other than anatase TiO2 and would increase the possible applications of oxide-based thin film devices.

  2. Arsenate adsorption structures on aluminum oxide and phyllosilicate mineral surfaces in smelter-impacted soils.

    PubMed

    Beaulieu, Brett T; Savage, Kaye S

    2005-05-15

    A clearer understanding of arsenic (As) retention and transport in forest soils impacted by copper smelter emissions may reduce risks to human health and provide insight into As behavior in the vadose zone. On Vashon-Maury Island in Puget Sound, As is predominantly associated with the fine (< 63 microm) fraction of surficial soils. X-ray diffraction of oriented samples from the < 2 microm size fraction indicate that clinochlore isthe dominant phyllosilicate. X-ray absorption spectroscopy (XAS) was employed to examine As oxidation state and local coordination environment in impacted soil samples. Arsenic is present as As(V) in tetrahedral coordination with oxygen, associated with aluminum (Al) octahedra in bidentate binuclear (bridging) structures with As-Al distances of 3.15 - 3.16 angstroms. Including multiple scattering (MS) paths derived from the arsenate tetrahedron in esperanzaite significantly improved the match between XAS fine structure (EXAFS) data and models generated from theoretical phase and amplitude functions. The data are interpreted to indicate arsenate adsorption onto poorly crystalline aluminum oxyhydroxides and/or the edges of clinochlore interlayer hydroxyl sheets with constrained geometries causing MS to be important This implies that As initially released from the smelter as particulate As(III) and As(V) oxides was oxidized, dissolved, and adsorbed onto soil minerals and colloids; no evidence for relic arsenic oxide was observed. Physical transport of arsenic oxide particles and As adsorbed on soil colloids may account for limited downward migration of As within the soil column. The oxidizing and mildly acidic pH conditions in the upper vadose zone promote stable sorption complexes; barring substantial changes in soil chemistry, As is not expected to experience significant mobilization.

  3. Ellipsometric Study of Oxide Films Formed on LDEF Metal Samples

    DTIC Science & Technology

    1992-02-01

    AN, P. M., PEACE, 0. T., and SLEBODNIK P. F. Surface Prparation of Aluminum for Ion Implantation. Metallography. v. 12, 1989, p. 21-26. 9. SMIT1i, D...reported in the litera- ture; the choice used was made by D. Y. Lynch and W. R. Hunter.11 There are two stoichio- metric copper oxides; cuprous oxide Cu...20 (red), and cupric oxide CuO (black). The copper-oxygen phase diagram shows a strong pressure dependence that causes CuO to be transformed into Cu 20

  4. Growth of alumina/metal composites into porous ceramics by the oxidation of aluminum

    SciTech Connect

    Watari, Takanori; Mori, Koichiro; Torikai, Toshio; Matsuda, Ohsaku . Dept. of Applied Chemistry)

    1994-10-01

    Ductile metal is incorporated into brittle ceramics to improve their fracture toughness. Of the many methods for fabricating ceramic/metal composites, the oxidation of a molten alloy (DIMOX process) is particularly interesting because it affords (1) ease of composite production, (2) low cost, and (3) near-net-shape capability. Alumina/metal composites were grown into the pores of porous alumina, porous aluminosilicate, and porous silicon carbide substrates through the oxidation of Al-Si (5 wt %) powder compacts coated with magnesia powder (11 mg/cm[sup 2]). The thickness of the resulting composite increased with oxidation time and temperature, and was proportional to (pore size)[sup 0.5] on using porous alumina. The composite thickness was more than 2 times larger in the silicon carbide and about 4 times larger in the aluminosilicate than in the alumina at 1,523 K for 1 h. The products using these three types of substrates consisted of alumina, aluminum, and silicon, except that a silicon carbide phase occurred when using the silicon carbide substrate. Silica and mullite in the aluminosilicate substrate changed to silicon and alumina, and silica in the silicon carbide substrate changed to silicon because of the reduction by aluminum.

  5. The fabrication and thermal properties of bismuth-aluminum oxide nanothermometers

    NASA Astrophysics Data System (ADS)

    Wang, Chiu-Yen; Chen, Shih-Hsun; Tsai, Ping-Hsin; Chiou, Chung-Han; Hsieh, Sheng-Jen

    2017-01-01

    Bismuth (Bi) nanowires, well controlled in length and diameter, were prepared by using an anodic aluminum oxide (AAO) template-assisted molding injection process with a high cooling rate. A high performance atomic layer deposition (ALD)-capped bismuth-aluminum oxide (Bi-Al2O3) nanothermometer is demonstrated that was fabricated via a facile, low-cost and low-temperature method, including AAO templated-assisted molding injection and low-temperature ALD-capped processes. The thermal behaviors of Bi nanowires and Bi-Al2O3 nanocables were studied by in situ heating transmission electron microscopy. Linear thermal expansion of liquid Bi within native bismuth oxide nanotubes and ALD-capped Bi-Al2O3 nanocables were evaluated from 275 °C to 700 °C and 300 °C to 1000 °C, respectively. The results showed that the ALD-capped Bi-Al2O3 nanocable possesses the highest working temperature, 1000 °C, and the broadest operation window, 300 °C-1000 °C, of a thermal-expanding type nanothermometer. Our innovative approach provides another way of fabricating core-shell nanocables and to further achieve sensing local temperature under an extreme high vacuum environment.

  6. Microleakage on Class V glass ionomer restorations after cavity preparation with aluminum oxide air abrasion.

    PubMed

    Corona, Silmara Aparecida Milori; Borsatto, Maria Cristina; Rocha, Renata Andréa Salvitti de Sá; Palma-Dibb, Regina Guenka

    2005-01-01

    This in vitro study assessed the marginal microleakage on class V cavities prepared with aluminum oxide air abrasion and restored with different glass ionomer cements. The cavities were prepared on the buccal and lingual surfaces of 15 sound third molars with an air- abrasion device (Kreativ Mach 4.1; New Image) using a 27.5-microm aluminum oxide particle stream, and were assigned to 3 groups of 10 cavities each. The restorative materials were: group I, a conventional glass ionomer cement (Ketac-Fil); groups II and III, resin-modified glass ionomer cements (Vitremer R and Fuji II LC, respectively). After placement of the restorations, the teeth were stored in distilled water at 37 degrees C for 24 h, polished and then submitted to a thermocycling regimen of 500 cycles, isolated, immersed in 0.2% Rhodamine B solution for 24 h, included and serially sectioned. Microleakage was assessed by viewing the specimens under an optical microscope connected to a color video camera and a computer. The images obtained were digitized and analyzed for microleakage using software that allows for a standard quantitative assessment of dye penetration in millimeters. Statistical analysis was done using the Kruskall-Wallis and Wilcoxon tests. Means of dye penetration (%) were: occlusal - I: 25.76 +/- 34.35, II: 20.00 +/- 42.16, III: 28.25 +/- 41.67; cervical - I: 23.72 +/- 41.84; II: 44.22 +/- 49.69, III: 39.27 +/- 50.74. No statistically significant differences (p>0.05) were observed among either the glass ionomer cements or the margins. In conclusion, class V cavities restored with either conventional or resin-modified glass ionomer cements after preparation with aluminum oxide air abrasion did not show complete sealing at the enamel and dentin/cementum margins.

  7. Effect of thermal annealing on the structural and optical properties of tris-(8-hydroxyquinoline)aluminum(III) (Alq3 ) films.

    PubMed

    Cuba, M; Muralidharan, G

    2015-05-01

    Tris-(8-hydroxyquionoline)aluminum (Alq3 ) was synthesized and coated on to a glass substrate using the dip coating method. The structural and optical properties of the Alq3 film after thermal annealing from 50°C to 300°C in 50° steps was studied. The films have been prepared with 2 to 16 layers (42-324 nm). The thickness and thermal annealing of Alq3 films were optimized for maximum luminescence yield. The Fourier transform infrared spectrum confirms the formation of quinoline with absorption in the region 700 - 500/cm. Partial sublimation and decomposition of quinoline ion was observed with the Alq3 films annealed at 300°C. The X-ray diffraction pattern of the Alq3 film annealed at 50°C to 150°C reveals the amorphous nature of the films. The Alq3 film annealed above 150°C were crystalline nature. Film annealed at 150°C exhibits a photoluminescence intensity maximum at 512 nm when excited at 390 nm. The Alq3 thin film deposited with 10 layers (220 nm) at 150°C exhibited maximum luminescence yield.

  8. Unidirectional oxide hetero-interface thin-film diode

    SciTech Connect

    Park, Youngmin; Lee, Eungkyu; Lee, Jinwon; Lim, Keon-Hee; Kim, Youn Sang

    2015-10-05

    The unidirectional thin-film diode based on oxide hetero-interface, which is well compatible with conventional thin-film fabrication process, is presented. With the metal anode/electron-transporting oxide (ETO)/electron-injecting oxide (EIO)/metal cathode structure, it exhibits that electrical currents ohmically flow at the ETO/EIO hetero-interfaces for only positive voltages showing current density (J)-rectifying ratio of ∼10{sup 5} at 5 V. The electrical properties (ex, current levels, and working device yields) of the thin-film diode (TFD) are systematically controlled by changing oxide layer thickness. Moreover, we show that the oxide hetero-interface TFD clearly rectifies an AC input within frequency (f) range of 10{sup 2} Hz < f < 10{sup 6} Hz, providing a high feasibility for practical applications.

  9. Control of Crystal Orientation and Diameter of Silicon Nanowire Using Anodic Aluminum Oxide Template

    NASA Astrophysics Data System (ADS)

    Shimizu, Tomohiro; Inoue, Fumihiro; Wang, Chonge; Otsuka, Shintaro; Tada, Yoshihiro; Koto, Makoto; Shingubara, Shoso

    2013-06-01

    The control of the crystal orientation and diameter of vertically grown epitaxial Si nanowires was demonstrated using a combination of a vapor-liquid-solid (VLS) growth technique and the use of an anodic aluminum oxide (AAO) template on a single-crystal Si substrate. The [100], [110], and [111] nanowires were selectively obtained by choosing the Si substrate with appropriate crystal orientation. The diameter of a Si nanowire in the AAO template could be controlled by the modification of the pore size of the AAO template with anodic voltage during anodization.

  10. Oxidation behavior in reaction-bonded aluminum-silicon alloy/alumina powder compacts

    SciTech Connect

    Yokota, S.H.

    1992-12-01

    Goal of this research is to determine the feasibility of producing low-shrinkage mullite/alumina composites by applying the reaction-bonded alumina (RBAO) process to an aluminum-silicon alloy/alumina system. Mirostructural and compositional changes during heat treatment were studied by removing samples from the furnace at different steps in the heating schedule and then using optical and scanning electron microscopy, EDS and XRD to characterize the powder compacts. Results suggest that the oxidation behavior of the alloy compact is different from the model proposed for the pure Al/alumina system.

  11. Formation of calcium in the products of iron oxide-aluminum thermite combustion in air

    NASA Astrophysics Data System (ADS)

    Gromov, A. A.; Gromov, A. M.; Popenko, E. M.; Sergienko, A. V.; Sabinskaya, O. G.; Raab, B.; Teipel, U.

    2016-10-01

    The composition of condensed products resulting from the combustion of thermite mixtures (Al + Fe2O3) in air is studied by precise methods. It is shown that during combustion, calcium is formed and stabilized in amounts of maximal 0.55 wt %, while is missing from reactants of 99.7 wt % purity. To explain this, it is hypothesized that a low-energy nuclear reaction takes place alongside the reactions of aluminum oxidation and nitridation, resulting in the formation of calcium (Kervran-Bolotov reaction).

  12. A simple dip coat patterning of aluminum oxide to constitute a bistable memristor

    NASA Astrophysics Data System (ADS)

    Sharma, Bindu; Rabinal, M. K.

    2016-12-01

    Charge transport studies on a bipolar resistive random access memory device based on aluminum oxide were successfully undertaken. The device was designed in a simple metal-insulator-metal format, which was characterized in detail for structural, morphological and electrical measurements. A low cost technique has been adopted for the formation of the memristive element, exhibiting three orders of magnitude change between its two states of conductivity. The obtained memristive behavior is explained based on evidence obtained from charge transport characteristics. Formation/rupture of the conducting filament by external electric field is found to be the main mechanism behind resistive switching.

  13. CRYSTALLINE CHROMIUM DOPED ALUMINUM OXIDE (RUBY) USE AS A LUMINESCENT SCREEN FOR PROTON BEAMS.

    SciTech Connect

    BROWN,K.A.; GASSNER,D.M.

    1999-03-29

    In our search for a better luminescent screen material, we tested pieces of mono-crystalline chromium doped aluminum oxide (more commonly known as a ruby) using a 24 GeV proton beam. Due to the large variations in beam intensity and species which are run at the Alternating Gradient Synchrotron (AGS), we hope to find a material which can sufficiently luminesce, is compatible in vacuum, and maintain its performance level over extended use. Results from frame grabbed video camera images using a variety of neutral density filters are presented.

  14. Selective-Area Growth of Transferable InN Nanocolumns by Using Anodic Aluminum Oxide Nanotemplates

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Zhang, Guozhen; Xu, Yang; Wu, Hao; Liu, Chang

    2017-02-01

    InN nanocolumn arrays were grown on c-plane sapphire with and without anodic aluminum oxide (AAO) nanotemplates. The crystalline quality of InN nanocolumns was significantly improved by selective-area growth (SAG) using AAO templates, as verified by X-ray diffraction measurements. Then, InN nanocolumns were transferred onto p-type silicon substrates after etching off the AAO templates. Current-voltage characteristic of the transferred n-InN/p-Si heterojunctions shows on/off ratio as high as 4.65 × 103 at 2 V. This work offers a potential way to grow transferable devices with improving performances.

  15. Effect of atomic layer deposition coatings on the surface structure of anodic aluminum oxide membranes.

    PubMed

    Xiong, Guang; Elam, Jeffrey W; Feng, Hao; Han, Catherine Y; Wang, Hsien-Hau; Iton, Lennox E; Curtiss, Larry A; Pellin, Michael J; Kung, Mayfair; Kung, Harold; Stair, Peter C

    2005-07-28

    Anodic aluminum oxide (AAO) membranes were characterized by UV Raman and FT-IR spectroscopies before and after coating the entire surface (including the interior pore walls) of the AAO membranes by atomic layer deposition (ALD). UV Raman reveals the presence of aluminum oxalate in bulk AAO, both before and after ALD coating with Al2O3, because of acid anion incorporation during the anodization process used to produce AAO membranes. The aluminum oxalate in AAO exhibits remarkable thermal stability, not totally decomposing in air until exposed to a temperature >900 degrees C. ALD was used to cover the surface of AAO with either Al2O3 or TiO2. Uncoated AAO have FT-IR spectra with two separate types of OH stretches that can be assigned to isolated OH groups and hydrogen-bonded surface OH groups, respectively. In contrast, AAO surfaces coated by ALD with Al2O3 display a single, broad band of hydrogen-bonded OH groups. AAO substrates coated with TiO2 show a more complicated behavior. UV Raman results show that very thin TiO2 coatings (1 nm) are not stable upon annealing to 500 degrees C. In contrast, thicker coatings can totally cover the contaminated alumina surface and are stable at temperatures in excess of 500 degrees C.

  16. Reflection of a probe pulse and thermal emission of electrons produced by an aluminum film heated by a femtosecond laser pulse

    SciTech Connect

    Bezhanov, S. G.; Ionin, A. A.; Kanavin, A. P.; Kudryashov, S. I.; Makarov, S. V.; Seleznev, L. V.; Sinitsyn, D. V.; Uryupin, S. A.

    2015-06-15

    It is shown that an experimental decrease in the reflection of a probe femtosecond pulse from an aluminum film heated by a higher-power femtosecond pulse can be quantitatively described taking into account the inhomogeneous distribution of the laser pulse field in the film and the evolution of the electron and lattice temperature during absorption of the heating inhomogeneous field. Analysis of the electron temperature evolution on the heated film surface combined with modern concepts about the influence of a surface volume charge on thermal emission gave the relation between the amount of emitted electrons and experimental data on the heating of the aluminum film by the femtosecond pulse.

  17. Optimization of synthesis protocols to control the nanostructure and the morphology of metal oxide thin films for memristive applications

    SciTech Connect

    Baldi, G. Bosi, M.; Attolini, G.; Berzina, T.; Mosca, R.; Ponraj, J. S.; Iannotta, S.

    2015-03-10

    We propose a multi-technique approach based on in-vacuum synthesis of metal oxides to optimize the memristive properties of devices that use a metal oxide thin film as insulating layer. Pulsed Microplasma Cluster Source (PMCS) is based on supersonic beams seeded by clusters of the metal oxide. Nanocrystalline TiO{sub 2} thin films can be grown at room temperature, controlling the oxide stoichiometry from titanium metal up to a significant oxygen excess. Pulsed Electron beam Deposition (PED) is suitable to grow crystalline thin films on large areas, a step towards producing device arrays with controlled morphology and stoichiometry. Atomic Layer Deposition (ALD) is a powerful technique to grow materials layer-by-layer, finely controlling the chemical and structural properties of the film up to thickness of 50-80 nm. We will present a few examples of metal-insulator-metal structures showing a pinched hysteresis loop in their current-voltage characteristic. The structure, stoichiometry and morphology of the metal oxide layer, either aluminum oxide or titanium dioxide, is investigated by means of scanning electron microscopy (SEM) and by Raman scattering.

  18. Chemical vapor deposition and atomic layer deposition of metal oxide and nitride thin films

    NASA Astrophysics Data System (ADS)

    Barton, Jeffrey Thomas

    Processes for depositing thin films with various electronic, optical, mechanical, and chemical properties are indispensable in many industries today. Of the many deposition methods available, chemical vapor deposition (CVD) has proved over time to be one of the most flexible, efficient, and cost-effective. Atomic layer deposition (ALD) is a newer process that is gaining favor as a method for depositing films with excellent properties and unparalleled precision. This work describes the development of novel CVD and ALD processes to deposit a variety of materials. Hafnium oxide and zirconium oxide show promise as replacements for SiO 2 as gate dielectrics in future-generation transistors. These high-k materials would provide sufficient capacitance with layers thick enough to avoid leakage from tunneling. An ALD method is presented here for depositing conformal hafnium oxide from tetrakis-(diethylamido)hafnium and oxygen gas. A CVD method for depositing zirconium oxide from tetrakis-(dialkylamido)zirconium and either oxygen gas or water vapor is also described. The use of copper for interconnects in integrated circuits requires improved diffusion barrier materials, given its high diffusivity compared to the previously-used aluminum and tungsten. Tungsten nitride has a low resistivity among barrier materials, and can be deposited in amorphous films that are effective diffusion barriers in layers as thin as a few nanometers. Here we demonstrate CVD and plasma-enhanced CVD methods to deposit tungsten nitride films from bis-(dialkylamido)bis-( tert-butylimido)tungsten precursors and ammonia gas. Recent findings had shown uniform copper growth on tantalum silicate films, without the dewetting that usually occurs on oxide surfaces. Tantalum and tungsten silicates were deposited by a CVD reaction from the reaction of either tris-(diethylamido)ethylimido tantalum or bis-(ethylmethylamido)-bis-( tert-butylimido)tungsten with tris-(tert-butoxy)silanol. The ability of evaporated

  19. Role of melt behavior in modifying oxidation distribution using an interface incorporated model in selective laser melting of aluminum-based material

    NASA Astrophysics Data System (ADS)

    Gu, Dongdong; Dai, Donghua

    2016-08-01

    A transient three dimensional model for describing the molten pool dynamics and the response of oxidation film evolution in the selective laser melting of aluminum-based material is proposed. The physical difference in both sides of the scan track, powder-solid transformation and temperature dependent physical properties are taken into account. It shows that the heat energy tends to accumulate in the powder material rather than in the as-fabricated part, leading to the formation of the asymmetrical patterns of the temperature contour and the attendant larger dimensions of the molten pool in the powder phase. As a higher volumetric energy density is applied (≥1300 J/mm3), a severe evaporation is produced with the upward direction of velocity vector in the irradiated powder region while a restricted operating temperature is obtained in the as-fabricated part. The velocity vector continuously changes from upward direction to the downward one as the scan speed increases from 100 mm/s to 300 mm/s, promoting the generation of the debris of the oxidation films and the resultant homogeneous distribution state in the matrix. For the applied hatch spacing of 50 μm, a restricted remelting phenomenon of the as-fabricated part is produced with the upward direction of the convection flow, significantly reducing the turbulence of the thermal-capillary convection on the breaking of the oxidation films, and therefore, the connected oxidation films through the neighboring layers are typically formed. The morphology and distribution of the oxidation are experimentally acquired, which are in a good agreement with the results predicted by simulation.

  20. The complex interface chemistry of thin-film silicon/zinc oxide solar cell structures.

    PubMed

    Gerlach, D; Wimmer, M; Wilks, R G; Félix, R; Kronast, F; Ruske, F; Bär, M

    2014-12-21

    The interface between solid-phase crystallized phosphorous-doped polycrystalline silicon (poly-Si(n(+))) and aluminum-doped zinc oxide (ZnO:Al) was investigated using spatially resolved photoelectron emission microscopy. We find the accumulation of aluminum in the proximity of the interface. Based on a detailed photoemission line analysis, we also suggest the formation of an interface species. Silicon suboxide and/or dehydrated hemimorphite have been identified as likely candidates. For each scenario a detailed chemical reaction pathway is suggested. The chemical instability of the poly-Si(n(+))/ZnO:Al interface is explained by the fact that SiO2 is more stable than ZnO and/or that H2 is released from the initially deposited a-Si:H during the crystallization process. As a result, Zn (a deep acceptor in silicon) is "liberated" close to the silicon/zinc oxide interface presenting the inherent risk of forming deep defects in the silicon absorber. These could act as recombination centers and thus limit the performance of silicon/zinc oxide based solar cells. Based on this insight some recommendations with respect to solar cell design, material selection, and process parameters are given for further knowledge-based thin-film silicon device optimization.

  1. Plasticity mechanisms in ultrafine grained freestanding aluminum thin films revealed by in-situ transmission electron microscopy nanomechanical testing

    SciTech Connect

    Idrissi, Hosni; Kobler, Aaron; Amin-Ahmadi, Behnam; Schryvers, Dominique; Coulombier, Michael; Pardoen, Thomas; Galceran, Montserrat; Godet, Stéphane; Kübel, Christian

    2014-03-10

    In-situ bright field transmission electron microscopy (TEM) nanomechanical tensile testing and in-situ automated crystallographic orientation mapping in TEM were combined to unravel the elementary mechanisms controlling the plasticity of ultrafine grained Aluminum freestanding thin films. The characterizations demonstrate that deformation proceeds with a transition from grain rotation to intragranular dislocation glide and starvation plasticity mechanism at about 1% deformation. The grain rotation is not affected by the character of the grain boundaries. No grain growth or twinning is detected.

  2. Effect of environment on iodine oxidation state and reactivity with aluminum.

    PubMed

    Smith, Dylan K; McCollum, Jena; Pantoya, Michelle L

    2016-04-28

    Iodine oxide is a highly reactive solid oxidizer and with its abundant generation of iodine gas during reaction, this oxidizer also shows great potential as a biocidal agent. A problem with using I2O5 in an energetic mixture is its highly variable reactive behavior. This study isolates the variable reactivity associated with I2O5 as a function of its chemical reaction in various environments. Specifically, aluminum fuel and iodine oxide powder are combined using a carrier fluid to aid intermixing. The carrier fluid is shown to significantly affect the oxidation state of iodine oxide, thereby affecting the reactivity of the mixture. Four carrier fluids were investigated ranging in polarity and water miscibility in increasing order from hexane < acetone < isopropanol < water as well as untreated, dry-mixed reactants. Oxidation state and reactivity were examined with experimental techniques including X-ray photoelectric spectroscopy (XPS) and differential scanning calorimetry (DSC). Results are compared with thermal equilibrium simulations. Flame speeds increased with polarity of the fluid used to intermix the powder and ranged from 180 to 1202 m s(-1). The I2O5 processed in the polar fluids formed hydrated states of iodine oxide: HIO3 and HI3O8; and, the nonpolar and dry-mixed samples formed: I2O4 and I4O9. During combustion, the hydrated iodine oxides rapidly dehydrated from HIO3 to HI3O8 and from HI3O8 to I2O5. Both steps release 25% of their mass as vapor during combustion. Increased gas generation enhances convective energy transport and accounts for the increase in reactivity seen in the mixtures processed in polar fluids. These results explain the chemical mechanisms underlying the variable reactivity of I2O5 that are a function of the oxide's highly reactive nature with its surrounding environment. These results will significantly impact the selection of carrier fluid in the synthesis approach for iodine containing reactive mixtures.

  3. Tailoring surface conditions for enhanced reactivity of aluminum powders with solid oxidizing agents

    NASA Astrophysics Data System (ADS)

    Padhye, Richa; Smith, Dylan K.; Korzeniewski, Carol; Pantoya, Michelle L.

    2017-04-01

    The effect of processing liquids on particle surface hydration and subsequent reactivity of mixtures containing aluminum (Al) with different oxidizing agents was investigated. Recently, polar processing liquids were shown to significantly increase the surface hydration layer on Al particles and effect the reactivity of Al combined with polytetrafluoroethylene (PTFE). Processing mixtures of Al and PTFE using hexane (e.g., a non-polar liquid) limited surface hydration and produced significantly lower flame speeds than the same mixture processed in isopropanol (e.g., a polar liquid). Increased surface hydroxyl concentration was linked to higher exothermic behavior within a pre-ignition reaction (PIR) which may contribute to higher overall flame speed. This study extends the previous analysis toward assessing the influence of processing liquid on reactivity of aluminum with other oxidizing agents, specifically CuO, MoO3 and I2O5. Results from DSC analysis show no PIR kinetics associated with Al and CuO or MoO3, and Al+ CuO showed no difference in reactivity as a function of processing liquid. But, MoO3 FTIR shows modified surface structures after treatment in a polar solvent. Correspondingly, Al + MoO3 processed in polar solvent exhibited increased flame speed by 19% when compared to Al + MoO3 processed in a non-polar liquid. For Al + I2O5, water in polar processing liquids produces various hydrated states of iodic acid (i.e., HIO3 and HI3O8). Changing the hydration state of I2O5 significantly impacts reactivity. Results from this study confirm that carrier fluid used to process Al with metal oxides can also alter the surface structure of the metal oxide, thereby promoting greater reactivity with Al. A polar carrier fluid not only modifies the surface of Al but also hydration sensitive metal oxides such as MoO3 and correspondingly promotes greater reactivity.

  4. Thin film zinc oxide deposited by CVD and PVD

    NASA Astrophysics Data System (ADS)

    Hamelmann, Frank U.

    2016-10-01

    Zinc oxide is known as a mineral since 1810, but it came to scientific interest after its optoelectronic properties found to be tuneable by p-type doping. Since the late 1980’s the number of publications increased exponentially. All thin film deposition technologies, including sol-gel and spray pyrolysis, are able to produce ZnO films. However, for outstanding properties and specific doping, only chemical vapor deposition and physical vapor deposition have shown so far satisfying results in terms of high conductivity and high transparency. In this paper the different possibilities for doping will be discussed, some important applications of doped ZnO thin films will be presented. The deposition technologies used for industrial applications are shown in this paper. Especially sputtering of aluminium doped Zinc Oxide (ZnO:Al or AZO) and LPCVD of boron doped Zinc Oxide (ZnO:B or BZO) are used for the commercial production of transparent conductive oxide films on glass used for thin film photovoltaic cells. For this special application the typical process development for large area deposition is presented, with the important trade-off between optical properties (transparency and ability for light scattering) and electrical properties (conductivity). Also, the long term stability of doped ZnO films is important for applications, humidity in the ambient is often the reason for degradation of the films. The differences between the mentioned materials are presented.

  5. Study of indium tin oxide films exposed to atomic axygen

    NASA Technical Reports Server (NTRS)

    Snyder, Paul G.; De, Bhola N.; Woollam, John A.; Coutts, T. J.; Li, X.

    1989-01-01

    A qualitative simulation of the effects of atomic oxygen has been conducted on indium tin oxide (ITO) films prepared by dc sputtering onto room-temperature substrates, by exposing them to an RF-excited oxygen plasma and characterizing the resulting changes in optical, electrical, and structural properties as functions of exposure time with ellipsometry, spectrophotometry, resistivity, and X-ray measurements. While the films thus exposed exhibit reduced resistivity and optical transmission; both of these effects, as well as partial crystallization of the films, may be due to sample heating by the plasma. Film resistivity is found to stabilize after a period of exposure.

  6. Structural characterization of impurified zinc oxide thin films

    SciTech Connect

    Trinca, L. M.; Galca, A. C. Stancu, V. Chirila, C. Pintilie, L.

    2014-11-05

    Europium doped zinc oxide (Eu:ZnO) thin films have been obtained by pulsed laser deposition (PLD). 002 textured thin films were achieved on glass and silicon substrates, while hetero-epilayers and homo-epilayers have been attained on single crystal SrTiO{sub 3} and ZnO, respectively. X-ray Diffraction (XRD) was employed to characterize the Eu:ZnO thin films. Extended XRD studies confirmed the different thin film structural properties as function of chosen substrates.

  7. Ordered fragmentation of oxide thin films at submicron scale

    PubMed Central

    Guo, L.; Ren, Y.; Kong, L. Y.; Chim, W. K.; Chiam, S. Y.

    2016-01-01

    Crack formation is typically undesirable as it represents mechanical failure that compromises strength and integrity. Recently, there have also been numerous attempts to control crack formation in materials with the aim to prevent or isolate crack propagation. In this work, we utilize fragmentation, at submicron and nanometre scales, to create ordered metal oxide film coatings. We introduce a simple method to create modified films using electroplating on a prepatterned substrate. The modified films undergo preferential fragmentation at locations defined by the initial structures on the substrate, yielding ordered structures. In thicker films, some randomness in the characteristic sizes of the fragments is introduced due to competition between crack propagation and crack creation. The method presented allows patterning of metal oxide films over relatively large areas by controlling the fragmentation process. We demonstrate use of the method to fabricate high-performance electrochromic structures, yielding good coloration contrast and high coloration efficiency. PMID:27748456

  8. Tungsten-vanadium oxide sputtered films for Electrochromic Devices

    SciTech Connect

    Michalak, F.; Richardson, T.; Rubin, M.; Slack, J.; von Rottkay, K.

    1998-10-01

    Mixed vanadium and tungsten oxide films with compositions ranging from 0 to 100% vanadium (metals basis) were prepared by reactive sputtering from metallic vanadium and tungsten targets in an atmosphere of argon and oxygen. The vanadium content varied smoothly with the fraction of total power applied to the vanadium target. Films containing vanadium were more color neutral than pure tungsten oxide films, tending to gray-brown at high V fraction. The electrochromic switching performance of these films was investigated by in situ monitoring of their visible transmittance during lithium insertion/extraction cycling in a non-aqueous electrolyte (1M LiClO{sub 4} in propylene carbonate). The solar transmittance and reflectance was measured ex situ. Films with vanadium content greater than about 15% exhibited a marked decrease in switching range. Coloration efficiencies followed a similar trend.

  9. Nonlinear reflection of a nanosecond laser pulse from thin aluminum film in the temperature range 2-14 kK

    NASA Astrophysics Data System (ADS)

    Karabutov, A. A.; Kaptilniy, A. G.; Ksenofontov, D. M.; Makarov, V. A.; Cherepetskaya, E. B.; Podymova, N. B.

    2015-11-01

    This letter aims to experimentally demonstrate the possibility of measuring the temporal dependencies of the surface temperature of an aluminum film confined by a transparent dielectric in the range below and above the critical temperature of aluminum (from 2 kK to 14 kK). Such temperatures are achieved under the action of a powerful linearly-polarized laser pulse of one nanosecond in duration onto the film’s surface. To find the temporal dependencies of the temperature of the aluminum film the nonlinear reflection coefficient of its irradiated surface is measured to determine the radiation of a Q-switched Nd:YAG laser at the fundamental wavelength.

  10. Phantom dosimetric study of nondivergent aluminum tissue compensator using ion chamber, TLD, and gafchromic film.

    PubMed

    Kinhikar, Rajesh A; Tambe, Chandrashekhar M; Upreti, Ritu R; Patkar, Sachin; Patil, Kalpana; Deshpande, Deepak D

    2008-01-01

    Anatomic contour irregularity and tissue inhomogeneity in head-and-neck radiotherapy can lead to significant dose inhomogeneity due to the presence of hot and cold spots across the treatment volumes. Missing tissue compensators (TCs) can overcome this dose inhomogeneity. The current study examines the capacity of 2-dimensional (2D) custom aluminum TCs fabricated at our hospital to improve the dose homogeneity across the treatment volume. The dosimetry of the 2D custom TCs was carried out in a specially designed head-and-neck phantom for anterior-posterior (AP) and posterior-anterior (PA) fields with an ion chamber, thermoluminscence dosimeters (TLDs), and film. The results were compared for compensated and uncompensated plans generated from the Eclipse treatment planning system. On average, open-field plans contained peak doses of 117%, optimally wedged-plans contained peak doses of 113%, and custom-compensated plans contained peak doses of 105%. The dose variation between prescribed and measured dose at midplane of the phantom was observed as high as 17%, which was reduced to 3.2% for the customized TC during ionometric measurements. It was further confirmed with TLDs, in a sagittal plane, that the high-dose region of 13.3% was reduced to 2.3%. The measurements carried out with the ion chamber, TLDs, and film were found in good agreement with each other and with Eclipse. Thus, a custom-made 2D TC is capable of reducing hot spots to improve overall dose homogeneity across the treatment volume.

  11. Reactive pulsed magnetron-sputtered tantalum oxide thin films

    NASA Astrophysics Data System (ADS)

    Nielsen, Matthew Christian

    Current high speed, advanced packaging applications require the use of integrated capacitors. Tantalum oxide is one material currently being considered for use in the capacitors; however, the deposition technique used to make the thin film dielectric can alter its performance. Pulsed magnetron reactive sputtering was investigated in this thesis as it offers a robust, clean, and low temperature deposition alternative. This is a new deposition technique created to control the negative effects of target poisoning; however, to understand the relationships between the deposition variables and the resultant film properties a thorough investigation is needed. The instantaneous voltage at the target was captured using a high speed digital oscilloscope. Three target oxidation states were imaged and identified to be that of the metallic and oxidized states with an abrupt transition region separating the two. Using high resolution X-ray photoelectron spectroscopy the bonding present in the deposited films was correlated to the oxidation state of the target. While operating the target in the metallic mode, a mix of oxidized, sub-oxide and metallic states were discovered. Alternatively, the bonding present in the films deposited when the target was in the oxidized state were that of fully oxidized tantalum pentoxide. The films deposited above the critical partial pressure demonstrated excellent leakage current densities. The exact magnitude of the leakage current density inversely scaled to the relative amount of oxygen included into the sputtering atmosphere. Detailed plot analysis showed that there were two different conduction mechanisms controlling the current flow in the capacitors. High frequency test vehicles were measured up to 10 GHz in order to determine the frequency response of the dielectric material. A circuit equivalent model describing the testing system and samples was created and utilized to fit the collected data. Overall, the technique of pulsed magnetron

  12. Coprecipitation of arsenate with metal oxides. 3. Nature, mineralogy, and reactivity of iron(III)-aluminum precipitates.

    PubMed

    Violante, Antonio; Pigna, Massimo; Del Gaudio, Stefania; Cozzolino, Vincenza; Banerjee, Dipanjan

    2009-03-01

    Coprecipitation involving arsenic with aluminum or iron has been studied because this technique is considered particularly efficient for removal of this toxic element from polluted waters. Coprecipitation of arsenic with mixed iron-aluminum solutions has received scant attention. In this work we studied (i)the mineralogy, surface properties, and chemical composition of mixed iron-aluminum oxides formed at initial Fe/Al molar ratio of 1.0 in the absence or presence of arsenate [As/ Fe+Al molar ratio (R) of 0, 0.01, or 0.1] and at pH 4.0, 7.0, and 10.0 and aged for 30 and 210 days at 50 degrees C and (ii) the removal of arsenate from the coprecipitates after addition of phosphate. The amounts of short-range ordered precipitates (ferrihydrite, aluminous ferrihydrite and/or poorly crystalline boehmite) were greater than those found in iron and aluminum systems (studied in previous works), due to the capacity of both aluminum and arsenate to retard or inhibitthe transformation of the initially formed precipitates into well-crystallized oxides (gibbsite, bayerite, and hematite). As a consequence, the surface areas of the iron-aluminum oxides formed in the absence or presence of arsenate were usually much larger than those of aluminum or iron oxides formed under the same conditions. Arsenate was found to be associated mainly into short-range ordered materials. Chemical composition of all samples was affected by pH, initial R, and aging. Phosphate sorption was facilitated by the presence of short-range ordered materials, mainly those richer in aluminum, but was inhibited by arsenate present in the samples. The quantities of arsenate replaced by phosphate, expressed as percentages of its total amount present in the samples, were particularly low, ranging from 10% to 26%. A comparison of the desorption of arsenate by phosphate from aluminum-arsenate and iron-arsenate (studied in previous works) and iron-aluminum-arsenate coprecipitates evidenced that phosphate has a greater

  13. High temperature coefficient of resistance molybdenum oxide and nickel oxide thin films for microbolometer applications

    NASA Astrophysics Data System (ADS)

    Jin, Yao O.; John, David Saint; Podraza, Nikolas J.; Jackson, Thomas N.; Horn, Mark W.

    2015-03-01

    Molybdenum oxide (MoOx) and nickel oxide (NiOx) thin films were deposited by reactive biased target ion beam deposition. MoOx thin film resistivity varied from 3 to 2000 Ω.cm with a temperature coefficient of resistance (TCR) from -1.7% to -3.2%/K, and NiOx thin film resistivity varied from 1 to 300 Ω.cm with a TCR from -2.2% to -3.3%/K, both easily controlled by varying the oxygen partial pressure. Biased target ion beam deposited high TCR MoOx and NiOx thin films are polycrystalline semiconductors and have good stability in air. Compared with commonly used vanadium oxide thin films, MoOx or NiOx thin films offer improved process control for resistive temperature sensors.

  14. Determination of oxygen diffusion kinetics during thin film ruthenium oxidation

    NASA Astrophysics Data System (ADS)

    Coloma Ribera, R.; van de Kruijs, R. W. E.; Yakshin, A. E.; Bijkerk, F.

    2015-08-01

    In situ X-ray reflectivity was used to reveal oxygen diffusion kinetics for thermal oxidation of polycrystalline ruthenium thin films and accurate determination of activation energies for this process. Diffusion rates in nanometer thin RuO2 films were found to show Arrhenius behaviour. However, a gradual decrease in diffusion rates was observed with oxide growth, with the activation energy increasing from about 2.1 to 2.4 eV. Further exploration of the Arrhenius pre-exponential factor for diffusion process revealed that oxidation of polycrystalline ruthenium joins the class of materials that obey the Meyer-Neldel rule.

  15. Determination of oxygen diffusion kinetics during thin film ruthenium oxidation

    SciTech Connect

    Coloma Ribera, R. Kruijs, R. W. E. van de; Yakshin, A. E.; Bijkerk, F.

    2015-08-07

    In situ X-ray reflectivity was used to reveal oxygen diffusion kinetics for thermal oxidation of polycrystalline ruthenium thin films and accurate determination of activation energies for this process. Diffusion rates in nanometer thin RuO{sub 2} films were found to show Arrhenius behaviour. However, a gradual decrease in diffusion rates was observed with oxide growth, with the activation energy increasing from about 2.1 to 2.4 eV. Further exploration of the Arrhenius pre-exponential factor for diffusion process revealed that oxidation of polycrystalline ruthenium joins the class of materials that obey the Meyer-Neldel rule.

  16. Patterning of Transparent Conducting Oxide Thin Films by Wet Etching for a-Si:H TFT-LCDs

    SciTech Connect

    Lan, J. H.; Kanicki, J.; Catalano, A.; Keane, J.; Den Boer, W.; Gu, T.

    1996-12-01

    The patterning characteristics of the indium tin oxide (ITO) thin films having different microstructures were investigated. Several etching solutions (HCl, HBr, and their mixtures with HNO3) were used in this study. We have found that ITO films containing a larger volume fraction of the amorphous phase show higher etch rates than those containing a larger volume fraction of the crystalline phase. Also, the crystalline ITO fims have shown a very good uniformity in patterning, and following the etching no ITO residue (unetched ITO) formation has been observed. In contrast, ITO residues were found after the etching of the films containing both amorphous and crystalline phases. We have also developed a process for the fabrication of the ITO with a tapered edge profile. The taper angle can be controlled by varying the ratio of HNO3 to the HCl in the etching solutions. Finally, ITO films have been found to be chemically unstable in a hydrogen containing plasma environment. On the contrary, aluminum doped zinc oxide (AZO) films, having an optical transmittance and electrical resisitivity comparable to ITO films, are very stable in the same hydrogen containing plasma environment. In addition, a high etch rate, no etching residue formation, and a uniform etching have been found for the AZO films, which make them suitable for a-Si:H TFT-LCD applications.

  17. Enhanced electroluminescence from nanoscale silicon p+ -n junctions made with an anodic aluminum oxide pattern.

    PubMed

    Hong, T; Chen, T; Ran, G Z; Wen, J; Li, Y Z; Dai, T; Qin, G G

    2010-01-15

    An enhancement of the electroluminescence (EL) from nanoscale silicon p(+)-n junctions made with an anodic aluminum oxide (AAO) pattern was demonstrated. The nanoporous AAO pattern with a pore density of 1.4 x 10(10) cm(-2) and a pore diameter of 50 +/- 10 nm was fabricated by the two-step anodic oxidation method on a n-type silicon wafer. The nanoscale AAO patterned Si p(+)-n junctions achieved an EL enhancement factor up to about 5 compared to the unpatterned Si p(+)-n junctions. The enhancement may originate from a reduction of nonradiative recombination due to partial passivation of the Si surface by the AAO pattern and improvement of the light extraction due to surface nanotextures.

  18. Cytotoxic properties of nanostructures based on aluminum oxide and hydroxide phases

    NASA Astrophysics Data System (ADS)

    Lozhkomoev, A. S.

    2016-11-01

    We study cytotoxic properties of low-dimensional nanostructures based on aluminum oxide and hydroxide phases with the morphology of agglomerated crumpled nanosheets. Among them are nanostructures of pseudoboehmite, γ-Al2O3 and θ-Al2O3. Nanostructures of pseudoboehmite synthesized by hydrothermal oxidation of AlN/Al nanoparticles in water. γ-Al2O3 and θ-Al2O3 nanostructures were prepared by heat treatment of pseudoboehmite. The greatest cytotoxic effect is seen for cells in contact with γ-Al2O3. An analysis of properties of the synthesized nanostructures shows that γ-Al2O3 causes a higher increase in pH values of the cell culture medium and neutralizes the acidity to a greater extent.

  19. Modification of Shape Memory Polymer Foams Using Tungsten, Aluminum Oxide, and Silicon Dioxide Nanoparticles.

    PubMed

    Hasan, S M; Thompson, R S; Emery, H; Nathan, A L; Weems, A C; Zhou, F; Monroe, M B B; Maitland, D J

    Shape memory polymer (SMP) foams were synthesized with three different nanoparticles (tungsten, silicon dioxide, and aluminum oxide) for embolization of cerebral aneurysms. Ultra-low density SMP foams have previously been utilized for aneurysm occlusion, resulting in a rapid, stable thrombus. However, the small cross section of foam struts can potentially lead to fracture and particulate generation, which would be a serious adverse event for an embolic device. The goal of this study was to improve the mechanical properties of the system by physically incorporating fillers into the SMP matrix. Thermal and mechanical characterization suggested minimal changes in thermal transition of the SMP nanocomposites and improved mechanical strength and toughness for systems with low filler content. Actuation profiles of the three polymer systems were tuned with filler type and content, resulting in faster SMP foam actuation for nanocomposites containing higher filler content. Additionally, thermal stability of the SMP nanocomposites improved with increasing filler concentration, and particulate count remained well below accepted standard limits for all systems. Extraction studies demonstrated little release of silicon dioxide and aluminum oxide from the bulk over 16 days. Tungstun release increased over the 16 day examination period, with a maximum measured concentration of approxiately 2.87 μg/mL. The SMP nanocomposites developed through this research have the potential for use in medical devices due to their tailorable mechanical properties, thermal resisitivity, and actuation profiles.

  20. A molecular beacon biosensor based on the nanostructured aluminum oxide surface.

    PubMed

    Che, Xiangchen; He, Yuan; Yin, Haocheng; Que, Long

    2015-10-15

    A new class of molecular beacon biosensors based on the nanostructured aluminum oxide or anodic aluminum oxide (AAO) surface is reported. In this type of sensor, the AAO surface is used to enhance the fluorescent signals of the fluorophore-labeled hairpin DNA. When a target DNA with a complementary sequence to that of the hairpin DNA is applied on the sensor, the fluorophores are forced to move away from the AAO surface due to the hybridization between the hairpin DNA and the target DNA, resulting in the significant decrease of the fluorescent signals. The observed signal reduction is sufficient to achieve a demonstrated detection limit of 10nM, which could be further improved by optimizing the AAO surface. The control experiments have also demonstrated that the bioassay used in the experiments has excellent specificity and selectivity, indicating the great promise of this type of sensor for diagnostic applications. Since the arrayed AAO micropatterns can be fabricated on a single chip in a cost-effective manner, the arrayed sensors could provide an ideal technical platform for studying fundamental biological process and monitoring disease biomarkers.

  1. An investigation of the electrical behavior of thermally-sprayed aluminum oxide

    SciTech Connect

    Swindeman, C.J.; Seals, R.D.; White, R.L.; Murray, W.P.; Cooper, M.H.

    1996-09-01

    Electrical properties of plasma-sprayed aluminum oxide coatings were measured at temperatures up to 600 C. High purity (> 99.5 wt% pure Al{sub 2}O{sub 3}) alumina powders were plasma-sprayed on stainless steel substrates over a range of power levels, using two gun configurations designed to attain different spray velocities. Key electrical properties were measured to evaluate the resultant coatings as potential insulating materials for electrostatic chucks (ESCs) being developed for semiconductor manufacturing. Electrical resistivity of all coatings was measured under vacuum upon heating and cooling over a temperature range of 20 to 600 C. Dielectric constants were also measured under the same test conditions. X-ray diffraction was performed to examine phase formation in the coatings. Results show the important of powder composition and careful selection and control of spray conditions for optimizing electrical behavior in plasma-sprayed aluminum oxide, and point to the need for further studies to characterize the relationship between high temperature electrical properties, measured plasma-spray variables, and specific microstructural and compositional coating features.

  2. Anodic aluminum oxide-epoxy composite acoustic matching layers for ultrasonic transducer application.

    PubMed

    Fang, H J; Chen, Y; Wong, C M; Qiu, W B; Chan, H L W; Dai, J Y; Li, Q; Yan, Q F

    2016-08-01

    The goal of this work is to demonstrate the application of anodic aluminum oxide (AAO) template as matching layer of ultrasonic transducer. Quarter-wavelength acoustic matching layer is known as a vital component in medical ultrasonic transducers to compensate the acoustic impedance mismatch between piezoelectric element and human body. The AAO matching layer is made of anodic aluminum oxide template filled with epoxy resin, i.e. AAO-epoxy 1-3 composite. Using this composite as the first matching layer, a ∼12MHz ultrasonic transducer based on soft lead zirconate titanate piezoelectric ceramic is fabricated, and pulse-echo measurements show that the transducer exhibits very good performance with broad bandwidth of 68% (-6dB) and two-way insertion loss of -22.7dB. Wire phantom ultrasonic image is also used to evaluate the transducer's performance, and the results confirm the process feasibility and merit of AAO-epoxy composite as a new matching material for ultrasonic transducer application. This matching scheme provides a solution to address the problems existing in the conventional 0-3 composite matching layer and suggests another useful application of AAO template.

  3. Anodic aluminum oxide with fine pore size control for selective and effective particulate matter filtering

    NASA Astrophysics Data System (ADS)

    Zhang, Su; Wang, Yang; Tan, Yingling; Zhu, Jianfeng; Liu, Kai; Zhu, Jia

    2016-07-01

    Air pollution is widely considered as one of the most pressing environmental health issues. Particularly, atmospheric particulate matters (PM), a complex mixture of solid or liquid matter suspended in the atmosphere, are a harmful form of air pollution due to its ability to penetrate deep into the lungs and blood streams, causing permanent damages such as DNA mutations and premature death. Therefore, porous materials which can effectively filter out particulate matters are highly desirable. Here, for the first time, we demonstrate that anodic aluminum oxide with fine pore size control fabricated through a scalable process can serve as effective and selective filtering materials for different types of particulate matters (such as PM2.5, PM10). Combining selective and dramatic filtering effect, fine pore size control and a scalable process, this type of anodic aluminum oxide templates can potentially serve as a novel selective filter for different kinds of particulate matters, and a promising and complementary solution to tackle this serious environmental issue.

  4. Excellent c-Si surface passivation by thermal atomic layer deposited aluminum oxide after industrial firing activation

    NASA Astrophysics Data System (ADS)

    Liao, B.; Stangl, R.; Ma, F.; Mueller, T.; Lin, F.; Aberle, A. G.; Bhatia, C. S.; Hoex, B.

    2013-09-01

    We demonstrate that by using a water (H2O)-based thermal atomic layer deposited (ALD) aluminum oxide (Al2O3) film, excellent surface passivation can be attained on planar low-resistivity silicon wafers. Effective carrier lifetime values of up to 12 ms and surface recombination velocities as low as 0.33 cm s-1 are achieved on float-zone wafers after a post-deposition thermal activation of the Al2O3 passivation layer. This post-deposition activation is achieved using an industrial high-temperature firing process which is commonly used for contact formation of standard screen-printed silicon solar cells. Neither a low-temperature post-deposition anneal nor a silicon nitride capping layer is required in this case. Deposition temperatures in the 100-400 °C range and peak firing temperatures of about 800 °C (set temperature) are investigated. Photoluminescence imaging shows that the surface passivation is laterally uniform. Corona charging and capacitance-voltage measurements reveal that the negative fixed charge density near the AlOx/c-Si interface increases from 1.4 × 1012 to 3.3 × 1012 cm-2 due to firing, while the midgap interface defect density reduces from 3.3 × 1011 to 0.8 × 1011 cm-2 eV-1. This work demonstrates that direct firing activation of thermal ALD Al2O3 is feasible, which could be beneficial for solar cell manufacturing.

  5. Real time monitoring of layer-by-layer polyelectrolyte deposition and bacterial enzyme detection in nanoporous anodized aluminum oxide.

    PubMed

    Krismastuti, Fransiska Sri Herwahyu; Bayat, Haider; Voelcker, Nicolas H; Schönherr, Holger

    2015-04-07

    Porous anodized aluminum oxide (pAAO) is a nanostructured material, which due to its optical properties lends itself to the design of optical biosensors where interactions in the pores of this material are transduced into interferometric reflectance shifts. In this study, a pAAO-based biosensor was developed as a biosensing platform to detect proteinase K, an enzyme which is a readily available model system for the proteinase produced by Pseudomonas aeruginosa. The pAAO pore walls are decorated by means of the layer-by-layer (LbL) deposition technique using poly(sodium-4-styrenesulfonate) and poly-l-lysine as negatively and positively charged polyelectrolytes, respectively. Interferometric reflectance spectroscopy utilized to observe the optical properties of pAAO during LbL deposition shows that the deposition of the polyelectrolyte onto the pore walls increases the net refractive index, thus red-shifting the effective optical thickness (EOT). Upon incubation with proteinase K, a conspicuous blue shift of the EOT is observed, which is attributed to the destabilization of the LbL film upon enzymatic degradation of the poly-l-lysine components. This result is confirmed by scanning electron microscopy results. Finally, as a proof-of-principle, we demonstrate the ability of the label-free pAAO-based biosensing platform to detect the presence of the proteinase K in human wound fluid, highlighting the potential for detection of bacterial infections in chronic wounds.

  6. Tungsten oxide-cellulose nanocrystal composite films for electrochromic applications

    NASA Astrophysics Data System (ADS)

    Stoenescu, Stefan; Badilescu, Simona; Sharma, Tanu; Brüning, Ralf; Truong, Vo-Van

    2016-12-01

    Composite films of tungsten oxide and CNCs are prepared through a sol-gel method and their electrochromic (EC) properties investigated. After mixing CNC gel into a tungsten oxide precursor solution, indium-tin-oxide-coated glass substrates are dipped into the composite solution and subsequently annealed at 170°C. The composite films consisted of CNCs dispersed in the tungsten oxide matrix. The resulting nanocomposite was found to be amorphous, exhibiting a high transmission modulation and very good cycling stability. After having tested a range of compositions, a film of WO3 with 10% CNC was found to be the most uniform and showed good EC performance. These results bode well for further work on CNC-EC composites for specific applications, especially when used on flexible substrates.

  7. Adsorption mechanisms of selenium oxyanions at the aluminum oxide/water interface.

    PubMed

    Peak, Derek

    2006-11-15

    Sorption processes at the mineral/water interface typically control the mobility and bioaccessibility of many inorganic contaminants such as oxyanions. Selenium is an important micronutrient for human and animal health, but at elevated concentrations selenium toxicity is a concern. The objective of this study was to determine the bonding mechanisms of selenate (SeO4(2-) and selenite (SeO3(2-) on hydrous aluminum oxide (HAO) over a wide range of reaction pH using extended X-ray absorption fine structure (EXAFS) spectroscopy. Additionally, selenate adsorption on corundum (alpha-Al2O3) was studied to determine if adsorption mechanisms change as the aluminum oxide surface structure changes. The overall findings were that selenite forms a mixture of outer-sphere and inner-sphere bidentate-binuclear (corner-sharing) surface complexes on HAO, selenate forms primarily outer-sphere surface complexes on HAO, and on corundum selenate forms outer-sphere surface complexes at pH 3.5 but inner-sphere monodentate surface complexes at pH 4.5 and above. It is possible that the lack of inner-sphere complex formation at pH 3.5 is caused by changes in the corundum surface at low pH or secondary precipitate formation. The results are consistent with a structure-based reactivity for metal oxides, wherein hydrous metal oxides form outer-sphere complexes with sulfate and selenate, but inner-sphere monodentate surface complexes are formed between sulfate and selenate and alpha-Me2O3.

  8. Interaction between a capacitor electrolyte and gamma-aluminum oxide studied by Fourier transform infrared spectroscopy.

    PubMed

    Száraz, Ildikó; Forsling, Willis

    2003-06-01

    The interaction between y-aluminum oxide and an ethylene glycol (EG) based capacitor electrolyte was investigated by Fourier transform infrared (FT-IR) spectroscopy. It was found that only a few ingredients of the electrolyte react with the oxide (azelaic acid, poly(1-vinyl-2-pyrrolidone) (PVP), and phosphoric acid); the others act as pH or conductivity buffers (boric acid, ammonia, and water). The adsorption of azelaic acid and PVP from the electrolyte was studied as a function of temperature, pH, and time, and the result was compared to the adsorption from model solutions of simpler composition. The influence of other components such as phosphoric acid both in the electrolyte and on the aluminum oxide was also investigated, as was the presence of water. At low pH and high temperature (T > or = 105 degrees C) the acid formed an ester with EG and this product adsorbed on the oxide surface. The PVP was attached to the adsorbed azelaic acid by hydrophobic interaction, which is pH independent. Ester formation was found to be catalyzed by other electrolyte ingredients like boric acid. At high pH, surface adsorption of azelaic acid occurs through a deprotonated species, which is mainly coordinated through outer-sphere complexation. At high temperature or after a long equilibration time, the surface of the alumina changed, resulting in less adsorption of the organic substances, independent of pH. This change is due to a selective adsorption of phosphate species from the electrolyte, which block active surface sites.

  9. Multifunctional Oxide Films for Advanced Multifunction RF Systems

    DTIC Science & Technology

    2007-09-14

    layers . Methods for the dielectric characterization of the epitaxial oxide films have been evaluated and applied in collaboration with Dr. Lanagan (Penn...quality MgO epitaxial layers that will be used for the integration of tunable oxides on SiC and IIl-nitride substrates or templates. A study of the impact...likely cause for increased dielectric losses. Control of layer stoichiometry: Oxides exhibit high densities of vacancy-type defects. This is known to lead

  10. Porous nickel oxide films for electrochemical capacitors

    SciTech Connect

    Liu, K.C.; Anderson, M.A.

    1995-12-31

    NiO/Ni composite thin films consisting of nano-sized particles have been found to perform as good electrodes in electrochemical capacitor applications. These films can provide a specific capacitance of 25--40 F/g. The low cost of raw materials and easy manufacturing process of this system should allow one to produce low-cost electrochemical capacitors.

  11. New method of treating dilute mineral acids using magnesium-aluminum oxide.

    PubMed

    Kameda, Tomohito; Yabuuchi, Fumiko; Yoshioka, Toshiaki; Uchida, Miho; Okuwaki, Akitsugu

    2003-04-01

    Mineral acids, such as H(3)PO(4), H(2)SO(4), HCl, and HNO(3,) were treated with magnesium-aluminum oxide (Mg-Al oxide), which behaved as a neutralizer and fixative of anions. Anion removal increased with increasing Mg-Al oxide quantity, time, Mg/Al molar ratio, and initial acid concentration. Up to 95% removal of anions was achieved in 0.5 N acids using a stoichiometric quantity of Mg(0.80)Al(0.20)O(1.10) for H(3)PO(4), 1.75 stoichiometric quantities for H(2)SO(4), or 2.5 stoichiometric quantities for HCl or HNO(3) at 20 degrees C over a period of 6 h. The final solutions were found to have a pH in the range of 8-12. Selectivity of acid removal was found to follow the following order: H(3)PO(4) > H(2)SO(4) > HCl > HNO(3). The equivalent of acid removal per 1 g of Mg-Al oxide decreased as the Mg/Al molar ratio of Mg-Al oxide increased.

  12. Stability and surface energies of wetted grain boundaries in aluminum oxide

    SciTech Connect

    Kim, D.Y. ); Wiederhorn, S.M.; Hockey, B.J.; Handwerker, C.A.; Blendell, J.E. )

    1994-02-01

    The stability of a calcium-aluminum-silicate liquid film between two near-basal plane surfaces of sapphire at 1650 C was studied. Samples were prepared having an average basal misorientation across the interface of 6--7 [degree] about <10[bar 1]0>. The interfaces varied in orientation from 0[degree] to [approximately]38 to the [0001] direction. Three types of interfaces were observed: faceted, solid-liquid interfaces; low-angle grain boundaries consisting of aligned arrays of dislocations; and boundaries consisting of aligned arrays of dislocations; and boundaries consisting of alternating regions of dislocations and faceted solid-liquid interfaces. The type of interface observed depended on the orientation of the interface and could be predicted by using a construction based on Wulff shapes. Because the type of interface depends on crystal alignment and interface angle, these results suggest an absolute methods of determining the surface free energy of wetted boundaries.

  13. Controlling Pore Geometries and Interpore Distances of Anodic Aluminum Oxide Templates via Three-Step Anodization.

    PubMed

    Lim, Jin-Hee; Wiley, John B

    2015-01-01

    Porous alumina membranes have attracted much attention because they are very useful templates for the fabrication of various nanostructures important to nanotechnology. However, there are challenges in controlling pore geometries and interpore distances in alumina templates while maintaining highly ordered hexagonal pore structures. Herein, a three-step anodization method is utilized to prepare anodic alumina templates with various pore morphologies (e.g., arched-shape, tree-like, branched-shape) and tunable interpore distances. Such structures are not found within the more traditional alumina templates fabricated by a two-step anodization of aluminum films. The range of interpore distances and pore diameters within the modified templates increases with increasing voltages. In contrast, under decreasing voltages, hexagonally ordered pores can also branch into several pores with smaller sizes and reduced interpore distances. Electrochemical growth of metal nanowires in the modified templates helps to highlight details of the pore structures and which pore channels are active.

  14. The Role of Entrained Surface Oxides in RS-PM Aluminum Alloys on Resultant Structures and Properties

    NASA Technical Reports Server (NTRS)

    Grant, N. J.

    1985-01-01

    The RS-PM aluminum alloys which show less than anticipated toughness properties were studied. After eliminating negative variables such as sodium and potassium in lithium containing alloys, hydrogen in all Al alloys, and trapped impurities from the atomization processing the data pointed to fine oxides, as the primary cause of poor toughness properties. The oxide content of aluminum powders increases with: decreasing powder size, deviations from spherical powder shapes, exposure to moist atmospheres either during atomization or in subsequent powder handling, and alloy compositions which contain significant amounts of lithium, magnesium, cerium, and other reactive elements.

  15. The formation and structure of the oxide and hydroxide chemisorbed phases at the aluminum surface, and relevance to hydrogen embrittlement

    NASA Astrophysics Data System (ADS)

    Francis, Michael; Kelly, Robert; Neurock, Matthew

    2010-03-01

    Aluminum alloys used in aerospace structures are susceptible to environmentally assisted cracking (EAC) induced by hydrogen embrittlement (HE) (Gangloff and Ives 1990). Crack growth experiments have demonstrated a linear relation between the relative humidity of the environment and crack growth rates, indicating the importance of water (Speidel and Hyatt 1972). While the presence of water has been demonstrated to be necessary for EAC of aluminum, crack growth rates have been linked to the diffusivity of hydrogen in aluminum (Gangloff 2003) and hydrogen densities at the crack tip as high as Al2H have been observed (Young and Scully 1998). While the mechanism by which hydrogen embrittles aluminum is yet not well understood, without the entry of hydrogen into the aluminum matrix, embrittlement would not occur. While at the crack tip high hydrogen concentrations exist, the solubility of hydrogen in aluminum is normal near 1 ppm (Wolverton 2004). In this work combined first principles and kinetic Monte Carlo methods will be used to examine the oxide and hydroxide structure resulting from exposure of aluminum to H2O or O2 and relevance to hydrogen entry as well as EAC is discussed.

  16. Synthesis and Oxidation Resistance of h-BN Thin Films

    NASA Astrophysics Data System (ADS)

    Stewart, David; Meulenberg, Robert; Lad, Robert

    Hexagonal boron nitride (h-BN) is an exciting 2D material for use in sensors and other electronic devices that operate in harsh, high temperature environments. Not only is h-BN a wide band gap material with excellent wear resistance and high temperature stability, but recent reports indicate that h-BN can prevent metallic substrates from oxidizing above 600°C in low O2 pressures. However, the PVD of highly crystalline h-BN films required for this oxidation protection has proven challenging. In this work, we have explored the growth of h-BN thin films by reactive RF magnetron sputtering from an elemental B target in an Ar/N2 atmosphere. The film growth rate is extremely slow and the resulting films are atomically smooth and homogeneous. Using DC biasing during deposition and high temperature annealing treatments, the degree of film crystallinity can be controlled. The oxidation resistance of h-BN films deposited on inert sapphire and reactive metal substrates such as Zr and ZrB2 has been examined by techniques such as XPS, XRD, and SEM after oxidation between 600 and 1200°C under varying oxygen pressures. The success of h-BN as a passivation layer for metallic substrates in harsh environments is shown to depend greatly on its crystalline quality and defects. Supported by the NSF SusChEM program.

  17. On the Discontinuity of Polycrystalline Silicon Thin Films Realized by Aluminum-Induced Crystallization of PECVD-Deposited Amorphous Si

    NASA Astrophysics Data System (ADS)

    Pan, Qingtao; Wang, Tao; Yan, Hui; Zhang, Ming; Mai, Yaohua

    2017-04-01

    Crystallization of glass/Aluminum (50, 100, 200 nm) /hydrogenated amorphous silicon (a-Si:H) (50, 100, 200 nm) samples by Aluminum-induced crystallization (AIC) is investigated in this article. After annealing and wet etching, we found that the continuity of the polycrystalline silicon (poly-Si) thin films was strongly dependent on the double layer thicknesses. Increasing the a-Si:H/Al layer thickness ratio would improve the film microcosmic continuity. However, too thick Si layer might cause convex or peeling off during annealing. Scanning electron microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX) are introduced to analyze the process of the peeling off. When the thickness ratio of a-Si:H/Al layer is around 1 to 1.5 and a-Si:H layer is less than 200 nm, the poly-Si film has a good continuity. Hall measurements are introduced to determine the electrical properties. Raman spectroscopy and X-ray diffraction (XRD) results show that the poly-Si film is completely crystallized and has a preferential (111) orientation.

  18. On the Discontinuity of Polycrystalline Silicon Thin Films Realized by Aluminum-Induced Crystallization of PECVD-Deposited Amorphous Si

    NASA Astrophysics Data System (ADS)

    Pan, Qingtao; Wang, Tao; Yan, Hui; Zhang, Ming; Mai, Yaohua

    2017-01-01

    Crystallization of glass/Aluminum (50, 100, 200 nm) /hydrogenated amorphous silicon (a-Si:H) (50, 100, 200 nm) samples by Aluminum-induced crystallization (AIC) is investigated in this article. After annealing and wet etching, we found that the continuity of the polycrystalline silicon (poly-Si) thin films was strongly dependent on the double layer thicknesses. Increasing the a-Si:H/Al layer thickness ratio would improve the film microcosmic continuity. However, too thick Si layer might cause convex or peeling off during annealing. Scanning electron microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX) are introduced to analyze the process of the peeling off. When the thickness ratio of a-Si:H/Al layer is around 1 to 1.5 and a-Si:H layer is less than 200 nm, the poly-Si film has a good continuity. Hall measurements are introduced to determine the electrical properties. Raman spectroscopy and X-ray diffraction (XRD) results show that the poly-Si film is completely crystallized and has a preferential (111) orientation.

  19. Oxidation of fluorinated amorphous carbon (a-CF(x)) films.

    PubMed

    Yun, Yang; Broitman, Esteban; Gellman, Andrew J

    2010-01-19

    Amorphous fluorinated carbon (a-CF(x)) films have a variety of potential technological applications. In most such applications these films are exposed to air and undergo partial surface oxidation. X-ray photoemission spectroscopy has been used to study the oxidation of fresh a-CF(x) films deposited by magnetron sputtering. The oxygen sticking coefficient measured by exposure to low pressures (<10(-3) Torr) of oxygen at room temperature is on the order of S approximately 10(-6), indicating that the surfaces of these films are relatively inert to oxidation when compared with most metals. The X-ray photoemission spectra indicate that the initial stages of oxygen exposure (<10(7) langmuirs) result in the preferential oxidation of the carbon atoms with zero or one fluorine atom, perhaps because these carbon atoms are more likely to be found in configurations with unsaturated double bonds and radicals than carbon atoms with two or three fluorine atoms. Exposure of the a-CF(x) film to atmospheric pressures of air (effective exposure of 10(12) langmuirs to O(2)) results in lower levels of oxygen uptake than the low pressure exposures (<10(7) langmuirs). It is suggested that this is the result of oxidative etching of the most reactive carbon atoms, leaving a relatively inert surface. Finally, low pressure exposures to air result in the adsorption of both nitrogen and oxygen onto the surface. Some of the nitrogen adsorbed on the surface at low pressures is in a reversibly adsorbed state in the sense that subsequent exposure to low pressures of O(2) results in the displacement of nitrogen by oxygen. Similarly, when an a-CF(x) film oxidized in pure O(2) is exposed to low pressures of air, some of the adsorbed oxygen is displaced by nitrogen. It is suggested that these forms of nitrogen and oxygen are bound to free radical sites in the film.

  20. Modeling the Growth of Aluminum Gallium Nitride ((Al)GaN) Films Grown on Aluminum Nitride (AlN) Substrates

    DTIC Science & Technology

    2011-03-01

    3.1 Slip Systems Analysis .....................................................................................................2 3.2 Simulations of...much like it has been done for hetero-epitaxial silicon-germanium ( SiGe ) films grown on silicon (Si) ( 1 , 2), which have the cubic zinc blende...calculations carried out using the Vienna Ab-Initio Simulation Package (VASP) code (4, 5 ) with projector augmented waves (generalized gradient

  1. Oxidation Behavior of In-Flight Molten Aluminum Droplets in the Twin-Wire Electric Arc Thermal Spray Process

    SciTech Connect

    Donna Post Guillen; Brian G. Williams

    2005-05-01

    This paper examines the in-flight oxidation of molten aluminum sprayed in air using the twin-wire electric arc (TWEA) thermal spray process. The oxidation reaction of aluminum in air is highly exothermic and is represented by a heat generation term in the energy balance. Aerodynamic shear at the droplet surface enhances the amount of in-flight oxidation by: (1) promoting entrainment and mixing of the surface oxides within the droplet, and (2) causing a continuous heat generation effect that increases droplet temperature over that of a droplet without internal circulation. This continual source of heat input keeps the droplets in a liquid state during flight. A linear rate law based on the Mott-Cabrera theory was used to estimate the growth of the surface oxide layer formed during droplet flight. The calculated oxide volume fraction of an average droplet at impact agrees well with the experimentally determined oxide content for a typical TWEA-sprayed aluminum coating, which ranges from 3.3 to 12.7%. An explanation is provided for the elevated, nearly constant surface temperature (~ 2000 oC) of the droplets during flight to the substrate and shows that the majority of oxide content in the coating is produced during flight, rather than after deposition.

  2. Growth control of the oxidation state in vanadium oxide thin films

    SciTech Connect

    Lee, Shinbuhm; Meyer, Tricia L.; Lee, Ho Nyung; Park, Sungkyun; Egami, Takeshi

    2014-12-01

    Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research but also technological applications that utilize the subtle change in the physical properties originating from the metal-insulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase pure epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V{sub 2}{sup +3}O{sub 3}, V{sup +4}O{sub 2}, and V{sub 2}{sup +5}O{sub 5}. A well pronounced MIT was only observed in VO{sub 2} films grown in a very narrow range of oxygen partial pressure P(O{sub 2}). The films grown either in lower (<10 mTorr) or higher P(O{sub 2}) (>25 mTorr) result in V{sub 2}O{sub 3} and V{sub 2}O{sub 5} phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO{sub 2} thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an improved MIT behavior.

  3. Growth control of the oxidation state in vanadium oxide thin films

    SciTech Connect

    Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; Lee, Ho Nyung

    2014-12-05

    Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research, but also technological applications that utilize the subtle change in the physical properties originating from the metalinsulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase pure epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V₂⁺²O₃, V⁺⁴O₂, and V₂⁺⁵O₅. A well pronounced MIT was only observed in VO₂ films grown in a very narrow range of oxygen partial pressure P(O₂). The films grown either in lower (< 10 mTorr) or higher P(O₂) (> 25 mTorr) result in V₂O₃ and V₂O₅ phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO₂ thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an 3 improved MIT behavior.

  4. Growth control of the oxidation state in vanadium oxide thin films

    NASA Astrophysics Data System (ADS)

    Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; Egami, Takeshi; Lee, Ho Nyung

    2014-12-01

    Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research but also technological applications that utilize the subtle change in the physical properties originating from the metal-insulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase pure epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V2 + 3 O 3 , V + 4 O 2 , and V2 + 5 O 5 . A well pronounced MIT was only observed in VO2 films grown in a very narrow range of oxygen partial pressure P(O2). The films grown either in lower (<10 mTorr) or higher P(O2) (>25 mTorr) result in V2O3 and V2O5 phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO2 thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an improved MIT behavior.

  5. Growth control of the oxidation state in vanadium oxide thin films

    DOE PAGES

    Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; ...

    2014-12-05

    Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research, but also technological applications that utilize the subtle change in the physical properties originating from the metalinsulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase puremore » epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V₂⁺²O₃, V⁺⁴O₂, and V₂⁺⁵O₅. A well pronounced MIT was only observed in VO₂ films grown in a very narrow range of oxygen partial pressure P(O₂). The films grown either in lower (< 10 mTorr) or higher P(O₂) (> 25 mTorr) result in V₂O₃ and V₂O₅ phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO₂ thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an 3 improved MIT behavior.« less

  6. High-Temperature, Oxidation-Resistant Thermocouples

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Gedwill, Michael A.

    1994-01-01

    Aluminum substituted for rhodium, which is scarce and expensive. Electromotive force increases with aluminum content in Pt/Al leg of Pt(Pt/Al) thermocouple. Wires baked longer in aluminizing bed produce larger voltages. Thermocouples containing platinum/aluminum legs used instead of thermocouples of type R in furnaces, heat engines, and chemical reactors. Expecially suited to high-velocity oxidizing environments. Constructed as thin-film sensors on turbine blades and vanes, where pre-oxidation provides insulating film needed between thermocouple legs. Because aluminum content slowly depleted by oxidation, long-term use recommended only where maximum temperature is 1,200 degrees C or less.

  7. The Effect of Silicon and Aluminum Additions on the Oxidation Resistance of Lean Chromium Stainless Steels

    SciTech Connect

    Dunning, J.S.; Alman, D.E.; Rawers, J.C.

    2001-09-01

    The effect of Si and Al additions on the oxidation of lean chromium austenitic stainless steels has been studied. A baseline composition of Fe-16Cr-16Ni-2Mn-1Mo was selected to allow combined Si and Al additions of up to 5 wt. pct. in a fully austenitic alloy. The baseline composition was selected using a net Cr equivalent equation to predict the onset of G-ferrite formation in austenite. Cyclic oxidation tests in air for 1000 hours were carried out on alloys with Si only or combined Si and Al additions in the temperature range 700 C to 800 C. Oxidation resistance of alloys with Si only additions were outstanding, particularly at 800 C. It was evident that different rate controlling mechanisms for oxidation were operative at 700 C and 800 C in the Si alloys. In addition, Si alloys pre-oxidized at 800 C, showed a zero weight gain in subsequent testing for 1000 hours at 700 C. The rate controlling mechanism in alloys with combined Si and Al addition for oxidation at 800 C was also different than alloys with Si only. SEM and ESCA analysis of the oxide films and base material at the oxide/base metal interface were conducted to study potential rate controlling mechanisms.

  8. Hole mobility modulation of solution-processed nickel oxide thin-film transistor based on high-k dielectric

    NASA Astrophysics Data System (ADS)

    Liu, Ao; Liu, Guoxia; Zhu, Huihui; Shin, Byoungchul; Fortunato, Elvira; Martins, Rodrigo; Shan, Fukai

    2016-06-01

    Solution-processed p-type oxide semiconductors have recently attracted increasing interests for the applications in low-cost optoelectronic devices and low-power consumption complementary metal-oxide-semiconductor circuits. In this work, p-type nickel oxide (NiOx) thin films were prepared using low-temperature solution process and integrated as the channel layer in thin-film transistors (TFTs). The electrical properties of NiOx TFTs, together with the characteristics of NiOx thin films, were systematically investigated as a function of annealing temperature. By introducing aqueous high-k aluminum oxide (Al2O3) gate dielectric, the electrical performance of NiOx TFT was improved significantly compared with those based on SiO2 dielectric. Particularly, the hole mobility was found to be 60 times enhancement, quantitatively from 0.07 to 4.4 cm2/V s, which is mainly beneficial from the high areal capacitance of the Al2O3 dielectric and high-quality NiOx/Al2O3 interface. This simple solution-based method for producing p-type oxide TFTs is promising for next-generation oxide-based electronic applications.

  9. Aerosol chemical vapor deposition of metal oxide films

    DOEpatents

    Ott, K.C.; Kodas, T.T.

    1994-01-11

    A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said substrate.

  10. Oxidative stress in blood and testicle of rat following intraperitoneal administration of aluminum and indium.

    PubMed

    Maghraoui, S; Clichici, Simona; Ayadi, A; Login, C; Moldovan, R; Daicoviciu, D; Decea, N; Mureşan, A; Tekaya, L

    2014-03-01

    Aluminum (Al) and indium (In) have embryotoxic, neurotoxic and genotoxic effects, oxidative stress being one of the possible mechanisms involved in their cytotoxicity. We have recently demonstrated that indium intraperitoneal (ip) administration induced histological disorganization of testicular tissue. In the present research we aimed at investigating the effect of Al and In ip administration on systemic and testicular oxidative stress status. Studies were performed on Wistar rats ip injected with Al, In or physiological solution for two weeks. Our results showed that In significantly decreased the absolute weight of testicles. Measurements of lactate dehydrogenase (LDH) and paraoxonase (PON) activities showed that In induced a significant augmentation in the first parameter but no changes were observed in the second. Both Al and In caused oxidative stress in testicles by increasing malondialdehyde (MDA) and protein carbonyls (PC) production. Concomitantly, thiol group (-SH) and glutathione (GSH) level were enhanced in the testicles. In the blood, while concentrations of MDA was not changed, those of GSH was significantly decreased in the Al and In groups. Our results indicated that Al and In cause oxidative stress both in blood and testicles but In has cytotoxic effect as well as negative impact on testicle weights. These findings could explain the testicular histological alterations previously described after In ip administration.

  11. Light emission and magnetic properties of aluminum films grown on SrTiO3 by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Wang, Y. J.; Zhou, W. Q.; Meng, M.; Wu, S. X.; Li, S. W.

    2016-06-01

    Aluminum films were grown on SrTiO3 (100) substrates using a plasma-assisted molecular beam epitaxy system. We found that the intensity of defect emission coming through the Al films was enhanced to two fold. Although the surface plasmon energy is far from the defect emission, off-resonance enhancement is still possible from Al/SrTiO3. Moreover, the samples with Al films exhibits ferromagnetism, with wasp-waist hysteresis loops and exchange bias effects. The ferromagnetism may be attributed to the charge transfer between Al and the SrTiO3 matrix. This work is valuable in developing SrTiO3 which is a promising material used in optical and magnetic related application.

  12. Role of Ball Milling of Aluminum Powders in Promotion of Aluminum-Water Reaction to Generate Hydrogen

    NASA Astrophysics Data System (ADS)

    Razavi-Tousi, S. S.; Szpunar, J. A.

    2014-09-01

    Effect of ball milling (BM) of an aluminum powder on hydrogen generation through a reaction with hot water was investigated. BM increased surface area of the aluminum particles, increased crystalline imperfections in the aluminum lattice, and removed a native oxide film on surface of the particles. The increase in surface area of the particles was studied by measurement of particle size and examination of cross section of the particles. The effect of crystalline imperfections was studied by room temperature recovery and high temperature annealing of the ball-milled particles. The effect of the native oxide film and its thickness was studied by exposing ball-milled aluminum particles to air for different durations. Hydrogen production capability of different aluminum powders after each of the above mentioned treatments was tested and correlated to microstructural changes.

  13. Compact laser molecular beam epitaxy system using laser heating of substrate for oxide film growth

    NASA Astrophysics Data System (ADS)

    Ohashi, S.; Lippmaa, M.; Nakagawa, N.; Nagasawa, H.; Koinuma, H.; Kawasaki, M.

    1999-01-01

    A high-temperature, oxygen compatible, and compact laser molecular beam epitaxy (laser MBE) system has been developed. The 1.06 μm infrared light from a continuous wave neodymium-doped yttrium aluminum garnet (Nd:YAG) laser was used to achieve a wide range and rapid control of substrate temperature in ultrahigh vacuum and at up to 1 atm oxygen pressure. The maximum usable temperature was limited to 1453 °C by the melting point of the nickel sample holder. To our knowledge, this is the highest temperature reported for pulsed laser deposition of oxide films. The efficient laser heating combined with temperature monitoring by a pyrometer and feedback control of the Nd:YAG laser power by a personal computer made it possible to regulate the substrate temperature accurately and to achieve high sample heating and cooling rates. The oxygen pressure and ablation laser triggering were also controlled by the computer. The accurate growth parameter control was combined with real-time in situ surface structure monitoring by reflection high energy electron diffraction to investigate oxide thin film growth in detail over a wide range of temperatures, oxygen partial pressures, and deposition rates. We have demonstrated the performance of this system by the fabrication of homoepitaxial SrTiO3 films as well as heteroepitaxial Sr2RuO4, and SrRuO3 films on SrTiO3 substrates at temperatures of up to 1300 °C. This temperature was high enough to change the film growth mode from layer by layer to step flow.

  14. Pulsed—Laser Deposition Of Oxide Thin Films And Laser—Induced Breakdown Spectroscopy Of Multi—Element Materials

    NASA Astrophysics Data System (ADS)

    Pedarnig, Johannes D.

    2010-10-01

    New results of the Linz group on pulsed—laser deposition (PLD) of oxide thin films and on laser—induced breakdown spectroscopy (LIBS) of multi-element materials are reported. High-Tc superconducting (HTS) films with enhanced critical current density Jc are produced by laser ablation of novel nano-composite ceramic targets. The targets contain insulating nano-particles that are embedded into the YBa2Cu3O7 matrix. Epitaxial double-layers of lithium-doped and aluminum-doped ZnO are deposited on r-cut sapphire substrates. Acoustic over-modes in the GHz range are excited by piezoelectric actuation of layers. Smooth films of rare-earth doped glass are produced by F2—laser ablation. The transport properties of HTS thin films are modified by light—ion irradiation. Thin film nano—patterning is achieved by masked ion beam irradiation. LIBS is employed to analyze trace elements in industrial iron oxide powder and reference polymer materials. Various trace elements of ppm concentration are measured in the UV/VIS and vacuum-UV spectral range. Quantitative LIBS analysis of major components in oxide materials is performed by calibration-free methods.

  15. Cadmium-Tin Oxide Transparent Conductive Thin Films

    NASA Astrophysics Data System (ADS)

    Stapinski, T.; Leja, E.; Marszalek, K.

    1986-09-01

    Cadmium-tin oxide (CTO) films have been prepared by d.c. reactive sputtering of Cd-Sn alloy targets in Ar-02 gas mixture. The electrical, optical and structural properties as well as the chemical composition of transparent conducting CTO films were found to depend on sputtering conditions. The value of optical band gap, optical constants, effective mass and relaxation time of electrons have been determined.

  16. Graphene Oxide Transparent Hybrid Film and Its Ultraviolet Shielding Property.

    PubMed

    Xie, Siyuan; Zhao, Jianfeng; Zhang, Bowu; Wang, Ziqiang; Ma, Hongjuan; Yu, Chuhong; Yu, Ming; Li, Linfan; Li, Jingye

    2015-08-19

    Herein, we first reported a facile strategy to prepare functional Poly(vinyl alcohol) (PVA) hybrid film with well ultraviolet (UV) shielding property and visible light transmittance using graphene oxide nanosheets as UV-absorber. The absorbance of ultraviolet light at 300 nm can be up to 97.5%, while the transmittance of visible light at 500 nm keeps 40% plus. This hybrid film can protect protein from UVA light induced photosensitive damage, remarkably.

  17. Nitrogen doped zinc oxide thin film

    SciTech Connect

    Li, Sonny Xiao-zhe

    2003-01-01

    To summarize, polycrystalline ZnO thin films were grown by reactive sputtering. Nitrogen was introduced into the films by reactive sputtering in an NO2 plasma or by N+ implantation. All ZnO films grown show n-type conductivity. In unintentionally doped ZnO films, the n-type conductivities are attributed to Zni, a native shallow donor. In NO2-grown ZnO films, the n-type conductivity is attributed to (N2)O, a shallow double donor. In NO2-grown ZnO films, 0.3 atomic % nitrogen was found to exist in the form of N2O and N2. Upon annealing, N2O decomposes into N2 and O2. In furnace-annealed samples N2 redistributes diffusively and forms gaseous N2 bubbles in the films. Unintentionally doped ZnO films were grown at different oxygen partial pressures. Zni was found to form even at oxygen-rich condition and led to n-type conductivity. N+ implantation into unintentionally doped ZnO film deteriorates the crystallinity and optical properties and leads to higher electron concentration. The free electrons in the implanted films are attributed to the defects introduced by implantation and formation of (N2)O and Zni. Although today there is still no reliable means to produce good quality, stable p-type ZnO material, ZnO remains an attractive material with potential for high performance short wavelength optoelectronic devices. One may argue that gallium nitride was in a similar situation a decade ago. Although we did not obtain any p-type conductivity, we hope our research will provide a valuable reference to the literature.

  18. Development of calcium zirconate-based hydrogen sensors with oxide reference electrodes for molten aluminum

    NASA Astrophysics Data System (ADS)

    Krishnan, Vivek

    Hydrogen is a major cause of gas porosity in aluminum and is frequently removed from the melt prior to casting. The degassing process can be better controlled if the hydrogen content in the melt is known. Thus, gas sensors which can make continuous in situ measurements in molten aluminum are needed. Current online hydrogen sensing systems are complex designs which are prohibitively expensive. Solid electrolyte based potentiometric sensors have been developed as an attractive alternate. These sensors have traditionally used a gas phase as the reference electrode. The present design has a condensed-phase reference electrode to avoid the need for transport of the reference gas into and out of the melt. The use of an oxide rather than a hydride phase reference is expected to considerably lower device cost and improve shelf life and reliability. The sensor element consists of a solid electrolyte tube based on 10 mol% Indoped CaZrO3, which was synthesized using both solid oxide and oxalate co-precipitation techniques. Precursor oxalate powders prepared using polymeric surfactants (PEG) were characterized using SEM, XRD, FTIR and particle size analysis. PEG was found to reduce particle size and also influence the process of perovskite formation. The oxalate co-precipitation technique enabled powder synthesis at reduced processing time and temperature. Closed-one-end tubes were slip cast and densified for use as solid electrolytes. Impedance spectroscopy and D.C. resistance measurements were made at temperatures between 650 and 900°C. Undoped CaZrO3 was found to be a p-type conductor in air. Indoped CaZrO3 acted as a proton conductor in air and argon+H2O, whereas the material was found to be a p-type conductor in pure argon. While bulk conduction was found to be homogenous with activation energies matching those from D.C. measurements, conduction across the grain boundary was found to be heterogeneous. Potentiometric sensors using In-doped CaZrO3 as the electrolyte, and

  19. Investigation of solution-processed bismuth-niobium-oxide films

    SciTech Connect

    Inoue, Satoshi; Ariga, Tomoki; Matsumoto, Shin; Onoue, Masatoshi; Miyasako, Takaaki; Tokumitsu, Eisuke; Shimoda, Tatsuya; Chinone, Norimichi; Cho, Yasuo

    2014-10-21

    The characteristics of bismuth-niobium-oxide (BNO) films prepared using a solution process were investigated. The BNO film annealed at 550°C involving three phases: an amorphous phase, Bi₃NbO₇ fluorite microcrystals, and Nb-rich cubic pyrochlore microcrystals. The cubic pyrochlore structure, which was the main phase in this film, has not previously been reported in BNO films. The relative dielectric constant of the BNO film was approximately 140, which is much higher than that of a corresponding film prepared using a conventional vacuum sputtering process. Notably, the cubic pyrochlore microcrystals disappeared with increasing annealing temperature and were replaced with triclinic β-BiNbO₄ crystals at 590°C. The relative dielectric constant also decreased with increasing annealing temperature. Therefore, the high relative dielectric constant of the BNO film annealed at 550°C is thought to result from the BNO cubic pyrochlore structure. In addition, the BNO films annealed at 500°C contained approximately 6.5 atm.% carbon, which was lost at approximately 550°C. This result suggests that the carbon in the BNO film played an important role in the formation of the cubic pyrochlore structure.

  20. Review of solution-processed oxide thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Si Joon; Yoon, Seokhyun; Kim, Hyun Jae

    2014-02-01

    In this review, we summarize solution-processed oxide thin-film transistors (TFTs) researches based on our fulfillments. We describe the fundamental studies of precursor composition effects at the beginning in order to figure out the role of each component in oxide semiconductors, and then present low temperature process for the adoption of flexible devices. Moreover, channel engineering for high performance and reliability of solution-processed oxide TFTs and various coating methods: spin-coating, inkjet printing, and gravure printing are also presented. The last topic of this review is an overview of multi-functional solution-processed oxide TFTs for various applications such as photodetector, biosensor, and memory.