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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. Corrosion Behavior of Aluminum Oxide Film Growth by Controlled Anodic Oxidation

    NASA Astrophysics Data System (ADS)

    Dumitrascu, V.; Benea, L.; Danaila, E.

    2017-06-01

    Due to the light weight and good corrosion resistance, nowadays aluminum and its alloys are used in different industries in order to decrease the maintenance costs and also to increase the equipments lifetime cycle. When aluminum and its alloys are exposed to the extreme environments, the native aluminum oxide film lose the anticorrosive properties that lead to the damage of equipments and increasing the costs. In order to improve the anticorrosive and mechanical performances of aluminum and its alloys, different techniques are used: organic coatings, the growth of a thick aluminum oxide film through different methods, etc. The most used method for aluminum oxide growth is anodic oxidation. Anodic oxidation is an electrochemical method that allows to growth an aluminum oxide film with controllable characteristics. The aim of present paper was to growth on 1050 aluminum alloy surface nanoporous aluminum oxide films with improved anticorrosive properties. The obtained nanoporous aluminum oxide films were characterized morphological and structural by scanning electron microscopy coupled with X-ray energy dispersive analyzer. The anticorrosive properties were evaluated by electrochemical methods such as: open circuit potential, electrochemical impedance spectroscopy and cyclic voltammetry. The results showed that anodic oxidation treatment improve the anticorrosive performances of 1050 aluminum alloy.

  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

    2017-01-01

    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.

  5. 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.

  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. 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.

  8. 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.

  9. High Transparent Conductive Aluminum-Doped Zinc Oxide Thin Films by Reactive Co-Sputtering (Postprint)

    DTIC Science & Technology

    2016-03-30

    AFRL-RX-WP-JA-2017-0144 HIGH TRANSPARENT CONDUCTIVE ALUMINUM - DOPED ZINC OXIDE THIN FILMS BY REACTIVE CO- SPUTTERING (POSTPRINT...TRANSPARENT CONDUCTIVE ALUMINUM -DOPED ZINC OXIDE THIN FILMS BY REACTIVE CO-SPUTTERING (POSTPRINT) 5a. CONTRACT NUMBER FA8650-16-D-5402-0001 5b. GRANT...ANSI Std. Z39-18 TD.11.pdf Optical Interference Coatings (OIC) 2016 © OSA 2016 1 High Transparent Conductive Aluminum -doped Zinc Oxide Thin

  10. 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.

  11. Use of aluminum oxide as a permeation barrier for producing thin films on aluminum substrates

    SciTech Connect

    Provo, James L.

    2016-07-15

    Aluminum has desirable characteristics of good thermal properties, good electrical characteristics, good optical properties, and the characteristic of being nonmagnetic and having a low atomic weight (26.98 g atoms), but because of its low melting point (660 °C) and ability as a reactive metal to alloy with most common metals in use, it has been ignored as a substrate material for use in processing thin films. The author developed a simple solution to this problem, by putting a permeation barrier of alumina (Al{sub 2}O{sub 3}) onto the surface of pure Al substrates by using a standard chemical oxidation process of the surface (i.e., anodization), before additional film deposition of reactive metals at temperatures up to 500 °C for 1-h, without the formation of alloys or intermetallic compounds to affect the good properties of Al substrates. The chromic acid anodization process used (MIL-A-8625) produced a film barrier of ∼(500–1000) nm of alumina. The fact that refractory Al{sub 2}O{sub 3} can inhibit the reaction of metals with Al at temperatures below 500 °C suggests that Al is a satisfactory substrate if properly oxidized prior to film deposition. To prove this concept, thin film samples of Cr, Mo, Er, Sc, Ti, and Zr were prepared on anodized Al substrates and studied by x-ray diffraction, Rutherford ion back scattering, and Auger/argon sputter surface profile analysis to determine any film substrate interactions. In addition, a major purpose of our study was to determine if ErD{sub 2} thin films could be produced on Al substrates with fully hydrided Er films. Thus, a thin film of ErD{sub 2} on an anodized Al substrate was prepared and studied, with and without the alumina permeation barrier. Films for study were prepared on 1.27 cm diameter Al substrates with ∼500 nm of the metals studied after anodization. Substrates were weighed, cleaned, and vacuum fired at 500 °C prior to use. The Al substrates were deposited using standard electron

  12. Tuning the Composition and Nanostructure of Pt/Ir Films via Anodized Aluminum Oxide Templated Atomic Layer Deposition

    DTIC Science & Technology

    2010-01-01

    REPORT Tuning the composition and nanostructure of Pt/Ir films via anodized aluminum oxide templated atomic layer deposition 14. ABSTRACT 16. SECURITY... oxide templates. Templated ALD provides advantages over alternative synthesis techniques, including improved film uniformity and conformality as...layer deposition, anodized aluminum oxide , platinum, iridium D. J. Comstock, S. T. Christensen, J. W. Elam, M. J. Pellin, and M. C. Hersam

  13. 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.

  14. Unexpected behaviour of one Pb monolayer deposited on aluminum oxide thin film grown on Ag(111)

    SciTech Connect

    Vizzini, Sébastien Bertoglio, M.; Oughaddou, Hamid; Hoarau, J. Y.; Biberian, J. P.; Aufray, B.

    2013-12-23

    Using scanning tunneling microscopy (STM), Auger electron spectroscopy, and low energy electron diffraction, we have observed a surprising complete dissolution at room temperature of one lead monolayer deposited by evaporation on an aluminum oxide thin film (∼0.8 nm thick) previously grown on Ag (111). We have observed the quasi-instantaneous diffusion of the lead deposit through the oxide layer to the silver/oxide interface. After the diffusion process, lead atoms form a Moiré superstructure, which is characterized by STM through the oxide layer. This unexpected behavior puts in light the very weak interaction between the aluminum oxide and the silver substrate.

  15. 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.

  16. 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}.

  17. 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.

  18. 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.

  19. 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.

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

    DTIC Science & Technology

    1980-02-01

    REFERENCES 20 Si ! V K.. LIST OF ILLUSTRATIONS FIGURE PG 1 Thermogram of Boehmite, Bayerite , and Anodic IOxide on Aluminum. 7 2 Porous Oxide and Barrier Layer...and bayerite . The data shown in the thermogram in Figure 1 does not show any direct relationship of anodic aluminum oxide to either compound. Since...y boehmite |0 S anodic film (I). C3 DC Foo.0 200.0 300.0 400.0 500.0 600.0 706.0 TEMPERATURE DEGREE CELCIUS Figure 1. Thermogram of Boehmite, Bayerite

  1. Formation of particulate Fe-Al films by selective oxidation of aluminum

    NASA Astrophysics Data System (ADS)

    Jang, Pyungwoo; Shin, Seung Chan

    2013-09-01

    Fe-5wt%Al films were RF-sputtered and annealed in an atmosphere of hydrogen and water vapor mixture at 1173 K for up to 200 min in order to selectively oxidize aluminum. As the annealing time increased, the morphology of the films changed from the continuous to the discontinuous type; thus, particulate Fe-Al films formed after 100 min. Thermodynamics simulation was performed to determine the ideal conditions for this process. Temperatures exceeding 1073 K are necessary to prevent iron from oxidation confirmed by both the depth profile in XPS and magnetic moment increment in VSM. Annealing the films in an atmosphere with a very low dew point of 77 K did not make the films become particulate. New findings are expected to be applied to the thin film inductors for GHz application as well as to manufacturing process of nanoparticles.

  2. Drop-photochemical deposition of aluminum oxide thin films from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Sato, Shunta; Ichimura, Masaya

    2017-04-01

    Aluminum oxide thin films were deposited onto fluorine-doped tin oxide-coated glass by drop photochemical deposition for the first time. The deposition solution was deionized water containing aluminum sulfate and sodium thiosulfate. Small amount of the solution was dropped on the substrate and irradiated with UV light. The solution was replaced with new one after 5 min irradiation, and the process was repeated 10 times. A film was not deposited without thiosulfate ions in the solution. The deposited films were transparent, and their band gap was larger than 4 eV. The O/Al composition ratio was about 1.2, smaller than the stoichiometric ratio 1.5.

  3. 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.

  4. Luminescence of europium-doped anode oxide films on titanium-aluminum composites

    NASA Astrophysics Data System (ADS)

    Sokol, V. A.; Pinaeva, M. M.; Gurskaya, E. A.; Stekol'Nikov, A. A.

    2000-03-01

    The luminescence of europium in anode oxide films (AOF) on titanium-aluminum film composites is investigated. It is shown that the intensity distribution in the continuous and line luminescence spectra of europium introduced into the AOF directly in the process of anodic oxidation essentially depends on the sequence of arrangement of the layers of metal films and on the temperature of their heat treatment preceding the process of anodic oxidation. It is established that the nature of the luminescence spectrum of the AOF correlates with the chronovoltammetry diagrams of anodic oxidation. Composites with a high degree of europium doping are found and methods of searching for composites for creating new materials of electronic technology are outlined.

  5. Bimodal spatial distribution of pores in anodically oxidized aluminum thin films

    NASA Astrophysics Data System (ADS)

    Behnke, J. F.; Sands, T.

    2000-12-01

    Though porous anodic aluminum oxide has been the subject of considerable research since the 1950s, little attention has been devoted to the characterization of the self-organization of the pore structures, and fewer of these studies have focused on anodization of thin films. The degree to which these structures self-organize, however, could play a vital role in future applications of porous anodic aluminum oxide. In this study a model is developed to describe pore ordering in thin anodized aluminum films. The model is based on a radial distribution function approach to describe the interpore spacings. Idealized one-dimensional and two-dimensional (2D) radial distribution functions are combined by linear superposition to approximate experimental radial distribution functions. Using these radial distribution functions, an order parameter is developed and an improved definition of pore spacing is constructed. This method confirms that the oxide initially forms with a highly frustrated porous structure and reorganizes toward greater 2D order as the oxide grows into the film.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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…

  11. 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…

  12. Characterization of monolayer formation on aluminum-doped zinc oxide thin films.

    PubMed

    Rhodes, Crissy L; Lappi, Simon; Fischer, Daniel; Sambasivan, Sharadha; Genzer, Jan; Franzen, Stefan

    2008-01-15

    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.

  13. 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.

  14. Plasma-Assisted Atomic Layer Growth of High-Quality Aluminum Oxide Thin Films

    NASA Astrophysics Data System (ADS)

    Jeong, Chang-Wook; Lee, Jang-Sik; Joo, Seung-Ki

    2001-01-01

    Thin aluminum oxide (Al2O3) films were grown by the plasma-assisted atomic layer controlled deposition (PAALD) method using Dimethylethylamine alane [(CH3)2(C2H5)N:AlH3] (DMEAA). Al was deposited by the PAALD method, then the Al films were oxidized into Al2O3 by plasma oxidation in the same chamber without breaking the vacuum. Al2O3 thin films of 15 nm thickness were prepared by repetition of this process. Thus prepared Al2O3 thin films exhibited a refractive index of 1.68. The thickness and the refractive index fluctuation of the film over a 4 inch wafer were ±2.3% and ±1.9%, respectively, for the deposited films. The leakage current density and breakdown field were measured to be about 10-8 A/cm2 at 1 MV/cm and 7 MV/cm, respectively. Considerable improvement of the electrical properties was realized by the post oxygen-plasma annealing at 200°C.

  15. 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.

  16. The influence of a thin gold film on the optical spectral characteristics of a porous anodic aluminum-oxide membrane

    NASA Astrophysics Data System (ADS)

    Ushakov, N. M.; Vasilkov, M. Yu.; Fedorov, F. S.

    2017-07-01

    We have experimentally studied how a thin mesostructured gold film, deposited onto one side of a porous anodic aluminum-oxide membrane, influences its optical spectral characteristics in a 200-900 nm wavelength range. It is established that the gold film only modifies the spectral characteristics of the composite membrane at light wavelengths above 500 nm. The presence of a thin gold film ensures the surface conductivity of membrane on a level of 3.4 × 106 Ω-1 m-1, retains optical transparency within 10-20%, leads to the appearance of anomalous dispersion in the long-wavelength part of the transmission spectrum, and reduces the bandgap width from 5.61 eV (in anodic aluminum oxide) to 4.51 eV (in the composite). The obtained anodic aluminum-oxide membranes with thin gold films can be used as transparent conducting electrodes in optoelectronic devices with large light transmitter/receiver active areas.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Rapid Thermal Annealing for Solution Synthesis of Transparent Conducting Aluminum Zinc Oxide Thin Films

    NASA Astrophysics Data System (ADS)

    Ullah, Sana; De Matteis, Fabio; Davoli, Ivan

    2017-07-01

    Transparent conducting oxide films with optimized dopant molar ratio have been prepared with limited pre- and postdeposition annealing duration of 10 min. Multiple aluminum zinc oxide (AZO) layers were spin-coated on ordinary glass substrates. The predeposition consolidation temperature and dopant molar ratio were optimized for electrical conductivity and optical transparency. Next, a group of films were deposited on Corning glass substrates from precursor solutions with the optimized dopant ratio, followed by postdeposition rapid thermal annealing (RTA) at different temperatures and in controlled environments. The lowest resistivity of 10.1 × 10-3 Ω cm was obtained for films receiving RTA at 600°C for 10 min each in vacuum then in N2-5%H2 environment, while resistivity of 20.3 × 10-3 Ω cm was obtained for films subjected to RTA directly in N2-5%H2. Optical measurements revealed average total transmittance of about 85% in the visible region. A direct allowed transition bandgap was determined based on the absorption edge with a value slightly above 3.0 eV, within the typical range for semiconductors. RTA resulted in desorption of oxygen with enhanced carrier concentration and crystallinity, which increased the carrier mobility with decreased bulk resistivity while maintaining the required optical transparency.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. High Stability Performance of Quinary Indium Gallium Zinc Aluminum Oxide Films and Thin-Film Transistors Deposited Using Vapor Cooling Condensation Method

    NASA Astrophysics Data System (ADS)

    Lin, Yung-Hao; Lee, Ching-Ting

    2017-08-01

    High-quality indium gallium zinc aluminum oxide (IGZAO) thin films with various Al contents have been deposited using the vapor cooling condensation method. The electron mobility of the IGZAO films was improved by 89.4% on adding Al cation to IGZO film. The change in the electron concentration and mobility of the IGZAO films was 7.3% and 7.0%, respectively, when the temperature was changed from 300 K to 225 K. These experimental results confirm the high performance and stability of the IGZAO films. The performance stability mechanisms of IGZAO thin-film transistors (TFTs) were investigated in comparison with IGZO TFTs.

  8. 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.

  9. Interference color of anodized aluminum oxide (AAO) films for sensor application

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Wang, Ming L.; Indacochea, J. Ernesto; Wang, H. Hau

    2009-03-01

    Anodized aluminum oxide (AAO) membranes are fabricated under different anodization potentials in dilute sulfuric acid. Here we report the growth of AAO under 10, 15, 20, and 25V. These AAO membranes consist of nanopores with pore-to-pore distance from 35 to 69 nm. When AAO membranes are kept thin (less than ~500 nm), together with the unreacted aluminum substrate, interference colors are observed. The inference color of the membrane is changed by its thickness and the pore-to-pore distance, which is controlled by the anodization time and voltage, respectively. By using thin film interference model to analyze the UV-Vis reflectance spectra, we can extract the thickness of the membrane. Thus the linear growth of AAO membrane in sulfuric acid with time during the first 15 minutes is validated. Coating poly (styrene sulfonate) (PSS) sodium salt and poly (allylamine hydrochloride) (PAH) layer by layer over the surface of AAO membrane consistently shifts the interference colors. The red shift of the UV-Vis reflectance spectrum is correlated to the number of layers. This color change due to molecular attachment and increasing thickness is a promising method for chemical sensing.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. Sol-gel deposition and plasma treatment of intrinsic, aluminum-doped, and gallium-doped zinc oxide thin films as transparent conductive electrodes

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    Zinc oxide and aluminum/gallium-doped zinc oxide thin films were deposited via sol-gel spin-coating technique. Employing plasma treatment as alternative to post thermal annealing, we found that the morphologies of these thin films have changed and the sheet resistances have been significantly enhanced. These plasma-treated thin films also show very good optical properties, with transmittance above 90% averaged over the visible wavelength range. Our best aluminum/gallium-doped zinc oxide thin films exhibit sheet resistances (Rs) of ~ 200 Ω/sq and ~ 150 Ω/sq, respectively.

  15. 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.

  16. 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.

  17. 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

  18. 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%.

  19. 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

  20. 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.

  1. Synthesis of Nanoporous Activated Iridium Oxide Films by Anodized Aluminum Oxide Templated Atomic Layer Deposition

    DTIC Science & Technology

    2010-11-01

    AIROFs) by repeated potential cycling or pulsing of Ir metal in acid or phosphate-buffered electrolytes [8,9]. IrOx films have also been synthesized by a...number of deposition strategies, including sputtering [10–12] and electrodeposition [13,14]. With all synthesis strategies, control of the film...prepare nanoporous materials [18,19]. ALD is a deposition technique utilizing iterative, self-limiting surface reactions to deposit thin films in a

  2. 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.

  3. 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.

  4. Effect on structural, optical and electrical properties of aluminum-doped zinc oxide films using diode laser annealing

    NASA Astrophysics Data System (ADS)

    Hsiao, Wen-Tse; Tseng, Shih-Feng; Chung, Chien-Kai; Chiang, Donyau; Huang, Kuo-Cheng; Lin, Keh-Moh; Li, Liang-Yan; Chen, Ming-Fei

    2015-05-01

    This study investigated the laser annealing characteristics of aluminum-doped zinc oxide (AZO) films using a diode laser source (808 nm) combined with moving stage with varying parameters, including laser fluence and speed of moving stage in air atmosphere. The commercial AZO thin films were prepared by RF magnetron sputtering on glass substrates. The films characteristics were systematically analyzed using a field emission scanning electron microscope, an atomic force microscope (AFM), an X-ray diffraction (XRD) equipment, an ultraviolet-visible-near-infrared (UV-vis-NIR) spectrophotometer, a four points probe instrument, and a Hall effect measurement system. The experimental results indicate that varying the laser fluence and annealing speed affected the optical, electrical, and structural characteristics of the AZO films. After annealing, approximately 90% of transmittance spectra exhibited slight changes in the visible region. All resistivity values of the laser-annealed AZO films decreased substantially from 4×10-2 Ω cm to 2.8×10-2 Ω cm. The absorption band edge moved toward shorter or longer wavelengths, depending on the annealing laser fluence and annealing speed. The optical energy band gap of the annealed AZO films increased because the carrier concentration of the annealed AZO films increased. The grain size increased in conjunction with the annealing speed. The AFM-derived root mean square (RMS) values decreased as the annealing speed increased, and the corresponding RMS values ranged from 1.4 to 1.9 nm.

  5. 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

  6. 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.

  7. 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.

  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. Water electrolysis-induced optical degradation of aluminum-doped zinc oxide films

    NASA Astrophysics Data System (ADS)

    Fang, Linggang; Fang, Guojia; Chen, Wanping; Li, Chun; Sheng, Su; Ma, Shuang; Zhao, Xingzhong

    2006-12-01

    A type of optical degradation of aluminium-doped zinc oxide (AZO) films due to water electrolysis-induced reduction reaction was reported. An experiment was designed in which AZO films were immersed in a 0.01 M NaOH aqueous solution as cathode to electrolyze water. Significant decreases in the optical transmission of the treated samples were observed. Studies by X-ray diffraction and scanning electron microscope showed that the degradation of AZO films was due to compositional and structural changes with the treatment of water electrolysis, which resulted from the reduction reaction of atomic hydrogen generated in the electrolysis of water. This optical degradation reflects the stability degradation of AZO films under water electrolysis environment.

  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. Aluminum-nitride codoped zinc oxide films prepared using a radio-frequency magnetron cosputtering system

    SciTech Connect

    Liu, D.-S.; Sheu, C.-S.; Lee, C.-T.

    2007-08-01

    Al-N codoped zinc oxide films were prepared using a radio-frequency magnetron cosputtering system at room temperature. AlN and ZnO materials were employed as the cosputtered targets. The as-deposited cosputtered films at various theoretical atomic ratios [Al/(Al+Zn) at. %] showed n-type conductive behavior in spite of the N atoms exceeding that of the Al dopants, indicating that the N-related acceptors were still inactive. The crystalline structure was obviously correlated with the cosputtered AlN contents and eventually evolved into an amorphous structure for the Al-N codoped ZnO film at a theoretical Al doping level reaching 60%. With an adequate postannealing treatment, the N-related acceptors were effectively activated and the p-type ZnO conductive behavior achieved. The appearance of the Zn{sub 3}N{sub 2} phase in the x-ray diffraction pattern of the annealed Al-N codoped ZnO film provided evidence of the nitrification of zinc ions. The redshift of the shallow level transition and the apparent suppression of the oxygen-related deep level emission investigated from the photoluminescence spectrum measured at room temperature were concluded to be influenced by the activated N-related acceptors. In addition, the activation of the N acceptors denoted as N-Zn bond and the chemical bond related to the Zn{sub 3}N{sub 2} crystalline structure were also observed from the associated x-ray photoelectron spectroscopy spectra.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. Atomic Layer Deposition of Rhenium-Aluminum Oxide Thin Films and ReOx Incorporation in a Metal-Organic Framework.

    PubMed

    Rimoldi, Martino; Hupp, Joseph T; Farha, Omar K

    2017-10-11

    Methyltrioxorhenium (ReO3Me) is introduced as the first rhenium atomic layer deposition (ALD) precursor and used to grow rhenium-aluminum oxide thin films in combination with trimethylaluminum (TMA-AlMe3). The growth rate of the smooth Re-Al oxide films, with general stoichiometry RexAlyO3x, has been monitored by in situ quartz crystal microbalance (QCM) and ex situ ellipsometry, and found to be 3.2 Å/cycle. X-ray photoelectron spectroscopy (XPS) revealed the mixed valent composition of the film with Re(III) species being the main component. In addition, ReO3Me has been successfully used to deposit rhenium oxide in NU-1000, a mesoporous zirconium-based metal-organic framework (MOF). The metalated MOF was found to retain porosity and crystallinity and to be catalytically active for ethene hydrogenation.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  4. 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.

  5. 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.

  6. 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}.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Effect of the Milling Time of the Precursors on the Physical Properties of Sprayed Aluminum-Doped Zinc Oxide (ZnO:Al) Thin Films

    PubMed Central

    Ramireddy, Thrinath Reddy; Venugopal, Velmurugan; Bellam, Jagadeesh Babu; Maldonado, Arturo; Vega-Pérez, Jaime; Velumani, Subramaniam; Olvera, María De La Luz

    2012-01-01

    Aluminum doped zinc oxide (ZnO:Al) thin films were deposited on soda-lime glass substrates by the chemical spray technique. The atomization of the solution was carried out by ultrasonic excitation. Six different starting solutions from both unmilled and milled Zn and Al precursors, dissolved in a mix of methanol and acetic acid, were prepared. The milling process was carried out using a planetary ball mill at a speed of 300 rpm, and different milling times, namely, 15, 25, 35, 45, and 60 min. Molar concentration, [Al]/[Zn] atomic ratio, deposition temperature and time, were kept at constant values; 0.2 M, 3 at.%, 475 °C, and 10 min, respectively. Results show that, under the same deposition conditions, electrical resistivities of ZnO:Al thin films deposited from milled precursors are lower than those obtained for films deposited from unmilled precursors. X-ray diffraction analysis revealed that all films display a polycrystalline structure, fitting well with the hexagonal wurtzite structure. Changes in surface morphology were observed by scanning electron microscopy (SEM) as well, since films deposited from unmilled precursors show triangular shaped grains, in contrast to films deposited from 15 and 35 min milled precursors that display thin slices with hexagonal shapes. The use of milled precursors to prepare starting solutions for depositing ZnO:Al thin films by ultrasonic pyrolysis influences their physical properties.

  16. 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.

  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. 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.

  19. 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.

  20. 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.

  1. X-ray photoelectron spectroscopy study of para-substituted benzoic acids chemisorbed to aluminum oxide thin films

    SciTech Connect

    Kreil, Justin; Ellingsworth, Edward; Szulczewski, Greg

    2013-11-15

    A series of para-substituted, halogenated (F, Cl, Br, and I) benzoic acid monolayers were prepared on the native oxide of aluminum surfaces by solution self-assembly and spin-coating techniques. The monolayers were characterized by x-ray photoelectron spectroscopy (XPS) and water contact angles. Several general trends are apparent. First, the polarity of the solvent is critical to monolayer formation. Protic polar solvents produced low coverage monolayers; in contrast, nonpolar solvents produced higher coverage monolayers. Second, solution deposition yields a higher surface coverage than spin coating. Third, the thickness of the monolayers determined from XPS suggests the plane of the aromatic ring is perpendicular to the surface with the carboxylate functional group most likely binding in a bidentate chelating geometry. Fourth, the saturation coverage (∼2.7 × 10{sup 14} molecules cm{sup −2}) is independent of the para-substituent.

  2. 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.

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

    SciTech Connect

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

    2016-09-15

    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 Al{sup 3+} ions distributed homogenously within the NiO matrix can significantly influence the crystallinity of Ni-Al LDH and NiO:Al{sup 3+} 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 Ni{sup 3+}/Ni{sup 2+} 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 Ni{sup 3+} 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. - Graphical abstract: The ratio of Ni{sup 3+}/Ni{sup 2+} 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, fast switching speed and excellent durability. Display Omitted.

  4. 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.

  5. Characterization of low-temperature microwave loss of thin aluminum oxide formed by plasma oxidation

    NASA Astrophysics Data System (ADS)

    Deng, Chunqing; Otto, M.; Lupascu, A.

    2014-01-01

    We report on the characterization of microwave loss of thin aluminum oxide films at low temperatures using superconducting lumped resonators. The oxide films are fabricated using plasma oxidation of aluminum and have a thickness of 5 nm. We measure the dielectric loss versus microwave power for resonators with frequencies in the GHz range at temperatures from 54 to 303 mK. The power and temperature dependence of the loss are consistent with the tunneling two-level system theory. These results are relevant to understanding decoherence in superconducting quantum devices. The obtained oxide films are thin and robust, making them suitable for capacitors in compact microwave resonators.

  6. 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.

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

    PubMed

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

    2015-11-30

    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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. Use of Aluminum in Air-Brazing Aluminum Oxide

    SciTech Connect

    Kim, Jin Yong Y.; Hardy, John S.; Weil, K. Scott

    2004-06-01

    A commercial aluminum foil was used to braze alumina plates in air. Although the outer surface of the aluminum oxidizes in air, the majority of the aluminum underneath remains unoxidized during brazing, allowing the ceramic pieces to be joined together with adequate strength. In fact, the joint exhibits a modest increase in bend strength when exposed to air at 850ºC for a prolonged period of time. Joint strength testing and subsequent examination of the fracture surfaces of the joints indicate that the joints are inherently ductile, even after long-term, high-temperature air exposure.

  15. Oxidation kinetics of aluminum diboride

    SciTech Connect

    Whittaker, Michael L.; Sohn, H.Y.; Cutler, Raymond A.

    2013-11-15

    The oxidation characteristics of aluminum diboride (AlB{sub 2}) and a physical mixture of its constituent elements (Al+2B) were studied in dry air and pure oxygen using thermal gravimetric analysis to obtain non-mechanistic kinetic parameters. Heating in air at a constant linear heating rate of 10 °C/min showed a marked difference between Al+2B and AlB{sub 2} in the onset of oxidation and final conversion fraction, with AlB{sub 2} beginning to oxidize at higher temperatures but reaching nearly complete conversion by 1500 °C. Kinetic parameters were obtained in both air and oxygen using a model-free isothermal method at temperatures between 500 and 1000 °C. Activation energies were found to decrease, in general, with increasing conversion for AlB{sub 2} and Al+2B in both air and oxygen. AlB{sub 2} exhibited O{sub 2}-pressure-independent oxidation behavior at low conversions, while the activation energies of Al+2B were higher in O{sub 2} than in air. Differences in the composition and morphology between oxidized Al+2B and AlB{sub 2} suggested that Al{sub 2}O{sub 3}–B{sub 2}O{sub 3} interactions slowed Al+2B oxidation by converting Al{sub 2}O{sub 3} on aluminum particles into a Al{sub 4}B{sub 2}O{sub 9} shell, while the same Al{sub 4}B{sub 2}O{sub 9} developed a needle-like morphology in AlB{sub 2} that reduced oxygen diffusion distances and increased conversion. The model-free kinetic analysis was critical for interpreting the complex, multistep oxidation behavior for which a single mechanism could not be assigned. At low temperatures, moisture increased the oxidation rate of Al+2B and AlB{sub 2}, but both appear to be resistant to oxidation in cool, dry environments. - Graphical abstract: Isothermal kinetic data for AlB{sub 2} in air, showing a constantly decreasing activation energy with increasing conversion. Model-free analysis allowed for the calculation of global kinetic parameters despite many simultaneous mechanisms occurring concurrently. (a) Time

  16. 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

  17. Method for Aluminum Oxide Thin Films Prepared through Low Temperature Atomic Layer Deposition for Encapsulating Organic Electroluminescent Devices.

    PubMed

    Li, Hui-Ying; Liu, Yun-Fei; Duan, Yu; Yang, Yong-Qiang; Lu, Yi-Nan

    2015-02-10

    Preparation of dense alumina (Al₂O₃) thin film through atomic layer deposition (ALD) provides a pathway to achieve the encapsulation of organic light emitting devices (OLED). Unlike traditional ALD which is usually executed at higher reaction n temperatures that may affect the performance of OLED, this application discusses the development on preparation of ALD thin film at a low temperature. One concern of ALD is the suppressing effect of ambient temperature on uniformity of thin film. To mitigate this issue, the pumping time in each reaction cycle was increased during the preparation process, which removed reaction byproducts and inhibited the formation of vacancies. As a result, the obtained thin film had both high uniformity and density properties, which provided an excellent encapsulation performance. The results from microstructure morphology analysis, water vapor transmission rate, and lifetime test showed that the difference in uniformity between thin films prepared at low temperatures, with increased pumping time, and high temperatures was small and there was no obvious influence of increased pumping time on light emitting performance. Meanwhile, the permeability for water vapor of the thin film prepared at a low temperature was found to reach as low as 1.5 × 10(-4) g/(m²·day) under ambient conditions of 25 °C and 60% relative humidity, indicating a potential extension in the lifetime for the OLED.

  18. Method for Aluminum Oxide Thin Films Prepared through Low Temperature Atomic Layer Deposition for Encapsulating Organic Electroluminescent Devices

    PubMed Central

    Li, Hui-Ying; Liu, Yun-Fei; Duan, Yu; Yang, Yong-Qiang; Lu, Yi-Nan

    2015-01-01

    Preparation of dense alumina (Al2O3) thin film through atomic layer deposition (ALD) provides a pathway to achieve the encapsulation of organic light emitting devices (OLED). Unlike traditional ALD which is usually executed at higher reaction n temperatures that may affect the performance of OLED, this application discusses the development on preparation of ALD thin film at a low temperature. One concern of ALD is the suppressing effect of ambient temperature on uniformity of thin film. To mitigate this issue, the pumping time in each reaction cycle was increased during the preparation process, which removed reaction byproducts and inhibited the formation of vacancies. As a result, the obtained thin film had both high uniformity and density properties, which provided an excellent encapsulation performance. The results from microstructure morphology analysis, water vapor transmission rate, and lifetime test showed that the difference in uniformity between thin films prepared at low temperatures, with increased pumping time, and high temperatures was small and there was no obvious influence of increased pumping time on light emitting performance. Meanwhile, the permeability for water vapor of the thin film prepared at a low temperature was found to reach as low as 1.5 × 10−4 g/(m2·day) under ambient conditions of 25 °C and 60% relative humidity, indicating a potential extension in the lifetime for the OLED. PMID:28787960

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. Photoemission study of tris(8-hydroxyquinoline) aluminum/aluminum oxide/tris(8-hydroxyquinoline) aluminum interface

    SciTech Connect

    Ding Huanjun; Zorba, Serkan; Gao Yongli; Ma Liping; Yang Yang

    2006-12-01

    The evolution of the interface electronic structure of a sandwich structure involving aluminum oxide and tris(8-hydroxyquinoline) aluminum (Alq), i.e. (Alq/AlO{sub x}/Alq), has been investigated with photoemission spectroscopy. Strong chemical reactions have been observed due to aluminum deposition onto the Alq substrate. The subsequent oxygen exposure releases some of the Alq molecules from the interaction with aluminum. Finally, the deposition of the top Alq layer leads to an asymmetry in the electronic energy level alignment with respect to the AlO{sub x} interlayer.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. All-Aluminum Thin Film Transistor Fabrication at Room Temperature.

    PubMed

    Yao, Rihui; Zheng, Zeke; Zeng, Yong; Liu, Xianzhe; Ning, Honglong; Hu, Shiben; Tao, Ruiqiang; Chen, Jianqiu; Cai, Wei; Xu, Miao; Wang, Lei; Lan, Linfeng; Peng, Junbiao

    2017-02-23

    Bottom-gate all-aluminum thin film transistors with multi conductor/insulator nanometer heterojunction were investigated in this article. Alumina (Al₂O₃) insulating layer was deposited on the surface of aluminum doping zinc oxide (AZO) conductive layer, as one AZO/Al₂O₃ heterojunction unit. The measurements of transmittance electronic microscopy (TEM) and X-ray reflectivity (XRR) revealed the smooth interfaces between ~2.2-nm-thick Al₂O₃ layers and ~2.7-nm-thick AZO layers. The devices were entirely composited by aluminiferous materials, that is, their gate and source/drain electrodes were respectively fabricated by aluminum neodymium alloy (Al:Nd) and pure Al, with Al₂O₃/AZO multilayered channel and AlOx:Nd gate dielectric layer. As a result, the all-aluminum TFT with two Al₂O₃/AZO heterojunction units exhibited a mobility of 2.47 cm²/V·s and an Ion/Ioff ratio of 10⁶. All processes were carried out at room temperature, which created new possibilities for green displays industry by allowing for the devices fabricated on plastic-like substrates or papers, mainly using no toxic/rare materials.

  11. All-Aluminum Thin Film Transistor Fabrication at Room Temperature

    PubMed Central

    Yao, Rihui; Zheng, Zeke; Zeng, Yong; Liu, Xianzhe; Ning, Honglong; Hu, Shiben; Tao, Ruiqiang; Chen, Jianqiu; Cai, Wei; Xu, Miao; Wang, Lei; Lan, Linfeng; Peng, Junbiao

    2017-01-01

    Bottom-gate all-aluminum thin film transistors with multi conductor/insulator nanometer heterojunction were investigated in this article. Alumina (Al2O3) insulating layer was deposited on the surface of aluminum doping zinc oxide (AZO) conductive layer, as one AZO/Al2O3 heterojunction unit. The measurements of transmittance electronic microscopy (TEM) and X-ray reflectivity (XRR) revealed the smooth interfaces between ~2.2-nm-thick Al2O3 layers and ~2.7-nm-thick AZO layers. The devices were entirely composited by aluminiferous materials, that is, their gate and source/drain electrodes were respectively fabricated by aluminum neodymium alloy (Al:Nd) and pure Al, with Al2O3/AZO multilayered channel and AlOx:Nd gate dielectric layer. As a result, the all-aluminum TFT with two Al2O3/AZO heterojunction units exhibited a mobility of 2.47 cm2/V·s and an Ion/Ioff ratio of 106. All processes were carried out at room temperature, which created new possibilities for green displays industry by allowing for the devices fabricated on plastic-like substrates or papers, mainly using no toxic/rare materials. PMID:28772579

  12. 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.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  15. 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.

  16. 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.

  17. Aluminum silicide microparticles transformed from aluminum thin films by hypoeutectic interdiffusion

    PubMed Central

    2014-01-01

    Aluminum silicide microparticles with oxidized rough surfaces were formed on Si substrates through a spontaneous granulation process of Al films. This microparticle formation was caused by interdiffusion of Al and Si atoms at hypoeutectic temperatures of Al-Si systems, which was driven by compressive stress stored in Al films. The size, density, and the composition of the microparticles could be controlled by adjusting the annealing temperature, time, and the film thickness. High-density microparticles of a size around 10 μm and with an atomic ratio of Si/Al of approximately 0.8 were obtained when a 90-nm-thick Al film on Si substrate was annealed for 9 h at 550°C. The microparticle formation resulted in a rapid increase of the sheet resistance, which is a consequence of substantial consumption of Al film. This simple route to size- and composition-controllable microparticle formation may lay a foundation stone for the thermoelectric study on Al-Si alloy-based heterogeneous systems. PMID:24994964

  18. 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.

  19. Quantitative in situ nanoindentation of aluminum films

    SciTech Connect

    Minor, Andrew M.; Stach, Eric A.; Morris Jr., J.W.

    2001-04-04

    We report the development of a method for quantitative, in situ nanoindentation in an electron microscope and its application to study the onset of deformation during the nanoindentation of aluminum films. The load-displacement curve developed during in situ nanoindentation shows the characteristic ''staircase'' instability at the onset of plastic deformation. The instability corresponds to the first appearance of dislocations in previously defect-free grains, and occurs at a force near that measured in conventional nanoindentation experiments on similarly oriented Al grains. Plastic deformation proceeds through the formation and propagation of prismatic loops punched into the material, and half-loops that emanate from the sample surface. This new experimental technique permits the direct observation of the microstructural mechanisms that operate at the onset of deformation.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. Characterization of Aluminum Oxide Tunnel Barrier for use in a Non-Local Spin Detection Device

    NASA Astrophysics Data System (ADS)

    Abel, Joseph; Garramone, John; Sitnitsky, Ilona; Labella, Vincent

    2010-03-01

    Aluminum oxide can be utilized as an interface layer between ferromagnetic metals and silicon to achieve spin injection into silicon. The goal of our research is to inject and readout spins using a non-local measurement device that utilizes 1-2 nm aluminum oxide interface layers as tunnel barriers. An important step of fabricating a non-local measurement device out of silicon is the growth of an aluminum oxide tunnel barrierfootnotetextO. van't Erve, A. Hanbicki, M. Holub, C. Li, C. Awo-Affouda, P. Thompson and B. Jonker, Appl. Phys. Lett. 91, 212109 (2007).. Aluminum Oxide thin films where grown using a Knudsen cell to deposit 1 nm, 2 nm, and 3 nm of aluminum. The films were then oxidized in O2. X-ray photoelectron spectroscopy (XPS) was performed to characterize the film stoichiometry, and the band gap. We will also report on current voltage measurements of these films after they have been capped with metal and compare the resistance area product to those calculated for spin injection into siliconfootnotetextB.-C. Min, K. Motohashi, C. Lodder, and R. Jansen, Nat. Mater. 5, 817 (2006). .

  5. Oxide Films RF Applications

    DTIC Science & Technology

    2006-06-01

    AUTHOR(S) 5d. PROJECT NUMBER SKOWRONSKI , Marek 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING...Report Title: Oxide Films RF applications University: Carnegie Mellon University PIs: M. Skowronski & P. Salvador Agency: Office of Naval Research Award

  6. Thermoelectric Properties of MnSi1.7 Films with Addition of Aluminum and Carbon

    NASA Astrophysics Data System (ADS)

    Hou, Q. R.; Liang, D.; Feng, X.; Zhao, W.; Chen, Y. B.; He, Y. J.

    Polycrystalline higher manganese silicide (MnSi1.7, HMS) films with addition of aluminum and carbon are prepared on thermally-oxidized silicon substrates by electron beam evaporation and magnetron sputtering, respectively. An aluminum intermediate layer and a carbon cap layer are used as the doping sources. It is found that both the Seebeck coefficient and electrical resistivity are dependent on the amount of aluminum and carbon added to the films. The Seebeck coefficient changes a little in the temperature range 300 to 433 K and decreases considerably above 433 K when aluminum is added to the film. When carbon is added to the film, however, the Seebeck coefficient increases slightly. With addition of aluminum and carbon, the resistivity decreases. As a result, the thermoelectric power factor increases, especially for films with carbon addition. Several activation energies (0.022-0.20 eV) are observed from the curves of logarithm of resistivity versus reciprocal temperature. The larger activation energies of 0.35 and 0.51 eV are consistent with the energy band gaps for higher manganese silicides.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Tunable infrared absorption and visible transparency of colloidal aluminum-doped zinc oxide nanocrystals.

    PubMed

    Buonsanti, Raffaella; Llordes, Anna; Aloni, Shaul; Helms, Brett A; Milliron, Delia J

    2011-11-09

    Plasmonic nanocrystals have been attracting a lot of attention both for fundamental studies and different applications, from sensing to imaging and optoelectronic devices. Transparent conductive oxides represent an interesting class of plasmonic materials in addition to metals and vacancy-doped semiconductor quantum dots. Herein, we report a rational synthetic strategy of high-quality colloidal aluminum-doped zinc oxide nanocrystals. The presence of substitutional aluminum in the zinc oxide lattice accompanied by the generation of free electrons is proved for the first time by tunable surface plasmon absorption in the infrared region both in solution and in thin films.

  16. 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.

  17. Solidification behavior of undercooled liquid aluminum oxide

    SciTech Connect

    Weber, J.K.R.; Anderson, C.D.; Merkley, D.R.; Nordine, P.C.

    1995-03-01

    Solidification of aluminum oxide from undercooled melts was investigated in containerless experiments. Specimens were levitated in a gas jet, stabilized with an acoustic positioning device, and melted with cw CO{sub 2} laser beams. Cooling curves were obtained by optical pyrometry when the laser intensity was reduced. The materials examined were high-purity Verneuil sapphire, 99.5% polycrystalline alumina, and oxide materials recovered from the effluent of an aluminum-fueled rocket motor. The degree of undercooling, the apparent temperature behavior during the thermal arrest on solidification, and the structure of the materials formed were different in argon and oxygen atmospheres. Undercooling of the sapphire and alumina materials was 360 {+-} 10 K in an oxygen atmosphere and approximately 450 K in argon. Melting and solidification of high-purity sapphire resulted in a dendritic and porous polycrystalline material in oxygen. Dense, larger crystals were obtained in argon. Products formed from 99.5% alumina were discolored and the cores were white, indicating impurity segregation effects. More reproducible behavior was observed for the sapphire and 99.5% alumina than for the tungsten-contaminated rocket motor effluent materials.

  18. The Oxidation Products of Aluminum Hydride and Boron Aluminum Hydride Clusters

    DTIC Science & Technology

    2016-01-04

    AFRL-AFOSR-VA-TR-2016-0075 The Oxidation Products of Aluminum Hydride and Boron Aluminum Hydride Clusters KIT BOWEN JOHNS HOPKINS UNIV BALTIMORE MD...Hydride and Boron Aluminum Hydride Clusters 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-14-1-0324 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) KIT...of both Aluminum Hydride Cluster Anions and Boron Aluminum Hydride Cluster Anions with Oxygen: Anionic Products The anionic products of reactions

  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. Long-range electrostatic forces on the surfaces of aluminum oxide and silica oxide.

    PubMed

    Novikov, S; Timoshcnkov, S

    2003-09-18

    The morphology and electrical microstructure of different anodic oxide films on aluminum and thermic oxide on surface p-type silica (KDB/100) were studied using atomic force microscopy and scanning capacitance microscopy. It was shown that the small basic element in the texture of both thin (0.05 microm) and thick (0.8 microm) oxide films represents a disklike element ('grain') approximately 200x200x30 nm in size. For films with a rough surface relief, the capacitance (and consequently, the surface potential) shows strong fluctuations in the vicinity of coarse (approximately 5-8 microm) pores. Because of this, the image of the surface obtained using atomic force microscopy does not coincide with that obtained by scanning capacitance microscopy (the opposite contrast effect). The manifestation of the opposite contrast correlates with an increase in the surface potential of the anodic oxide films measured by an independent method. A series of experiments under atmospheric conditions at different distances from the end of the cantilever to the surface of anodic oxide films showed that the influence of the surface field is detectable at long distances (up to 0.7 microm). It was shown that at a test temperature of 120 degrees C, the opposite contrast disappears: the images obtained in the semicontact (atomic force microscopy) and non-contact (scanning capacitance microscopy) modes coincide with each other. The results obtained suggest a relationship between the formation of electrostatic nanosized irregularities at the surface of oxide films and the sorption of water molecules under atmospheric conditions.

  2. 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.

  3. 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.

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

    SciTech Connect

    R. Farrell; V. R. Pagan; A. Kabulski; Sridhar Kuchibhatl; J. Harman; K. R. Kasarla; L. E. Rodak; P. Famouri; J. Peter Hensel; D. Korakakis

    2008-05-01

    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.

  5. Fabrication of Crystalline Indium Tin Oxide Nanobasket Electrodes using Aluminum Anodic Oxide Template

    NASA Astrophysics Data System (ADS)

    Wang, Gou-Jen; Chen, He-Tsing; Yang, Hsihang

    2008-07-01

    Fabrication of crystalline indium tin oxide (ITO) nanobasket electrodes shaped by an anodic aluminum oxide (AAO) template for better electron conductivity is presented. ITO films were deposited on porous AAO templates by RF magnetron sputtering. The sputter-coated ITO films were characterized by field-emission scanning electron microscopy (FESEM) to illustrate the nanobasket morphologies. The compositions of the ITO films were characterized by energy-dispersive X-ray (EDS) analysis. X-ray diffraction (XRD) analysis was conducted to evaluate the crystallinity. The crystallinity can be enhanced by annealing at 300 °C. Although the conductivity of the ITO nanobasket film is larger than that of the conventional ITO thin film, the harvest efficiency can be markedly increased due to the nanobasket structure which enables most of the photoexcited electrons to reach their nearest electrode before losing their momentum. The presented ITO nanobasket films can be further used as a more effective electrode material for photovoltaics such as dye-sensitized solar cells (DSSCs).

  6. 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.

  7. 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.

  8. 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.

  9. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... the solution obtained by boiling 10 grams of the chromium-cobalt-aluminum oxide for 15 minutes in 50..., and set by annealing. (2) The quantity of the color additive does not exceed 2 percent by weight of...

  10. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... the solution obtained by boiling 10 grams of the chromium-cobalt-aluminum oxide for 15 minutes in 50..., and set by annealing. (2) The quantity of the color additive does not exceed 2 percent by weight of...

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

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... the solution obtained by boiling 10 grams of the chromium-cobalt-aluminum oxide for 15 minutes in 50..., and set by annealing. (2) The quantity of the color additive does not exceed 2 percent by weight of...

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

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... the solution obtained by boiling 10 grams of the chromium-cobalt-aluminum oxide for 15 minutes in 50..., and set by annealing. (2) The quantity of the color additive does not exceed 2 percent by weight of...

  13. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... the solution obtained by boiling 10 grams of the chromium-cobalt-aluminum oxide for 15 minutes in 50..., and set by annealing. (2) The quantity of the color additive does not exceed 2 percent by weight of...

  14. Thermal oxidation of the surface of binary aluminum alloys with rare-earth metals

    NASA Astrophysics Data System (ADS)

    Akashev, L. A.; Popov, N. A.; Kuznetsov, M. V.; Shevchenko, V. G.

    2015-05-01

    The kinetics of oxidation of the surface of Al alloys with 1-2.5 at % rare-earth metals (REMs) at 400-500°C in air was studied by ellipsometry and X-ray photoelectron spectroscopy (XPS). The addition (1-2.5 at % REM) of all rare-earth metals to aluminum was shown to increase the thickness of the oxide layer. The addition of surfactant and chemically active REMs (Yb, Sm, La, and Ce) increased the rate of oxidation of solid aluminum most effectively. The oxidation can be accelerated by the polymorphic transformations of the individual REM oxides in the film. The surface activity of Sm with respect to solid Al was confirmed by XRS.

  15. 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.

  16. 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).

  17. 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.

  18. 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

  19. 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.

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

    DOEpatents

    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.

  1. 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

  2. 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.

  3. Effect of surface oxidation on emissivity properties of pure aluminum in the near infrared region

    NASA Astrophysics Data System (ADS)

    Zhang, Kaihua; Yu, Kun; Liu, Yufang; Zhao, Yuejin

    2017-08-01

    Emissivity is a basic thermo physical property of materials and determines the precision of radiation thermometry. The aim of this paper is to study the effect of surface oxidation on the infrared emissivity properties of pure aluminum. The emissivity data presented in this study covers the spectral range between 0.8 and 2.2 µm and temperatures from 473 to 873 K. The samples with different oxidation time were prepared under a controlled environment. The morphology and composition of the samples were characterized by metallographic microscope and XRD techniques before and after oxidation. The thickness of oxide film with different oxidation time was accurately measured by spectroscopic ellipsometer and a parabolic growth was found. In addition, the interference model of an oxidized metal substrate is established to explain the influence of the oxide film thickness on the emissivity. The thickness of oxide film when the interference effect occurs was calculated according to the interference model. The data shows that the maximum value measured was less than the thickness value at the first order constructive interference. Neither peaks nor valleys were observed in emissivity measurements with different oxidation time at 873 K, which could be related to the thin oxide film on sample surface.

  4. Thin Films of Polypyrrole on Particulate Aluminum

    DTIC Science & Technology

    2009-02-01

    C H R I S T O P H E R V E T T E R , X I A O N I N G Q I , S U B R A M A N Y A M V . K A S I S O M A Y A J U L A , A N D Thin Films of Polypyrrole on...1. REPORT DATE FEB 2009 2. REPORT TYPE 3. DATES COVERED 00-00-2009 to 00-00-2009 4. TITLE AND SUBTITLE Thin Films of Polypyrrole on...layer 3 Why Polypyrrole /Flake? Polypyrrole  Poor mechanical properties  Poor adhesion  Solubility issues  Continuous layer needed 4 Polypyrrole Coated

  5. 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.

  6. Degradation of perfluoropolyethers catalyzed by aluminum oxide

    NASA Astrophysics Data System (ADS)

    Kasai, Paul H.; Tang, Wing T.; Wheeler, Patrick

    1991-09-01

    Thermal stabilities of perfluoropolyethers, Fomblin Z, Fomblin Y, Krytox, and Demnum in the presence of Al 2O 3 were examined. Fomblin Z was found to degrade at 200°C in two stages, the slow first stage, and the vigorous second stage leading to complete loss of fluid. It is concluded that oxide-to-halide conversion occurs on Al 2O 3 surface during the first stage. The second stage is attributed to a catalytic process induced by Lewis acid AlF 3. Based on NMR and mass spectroscopic evidences the following reaction mechanism is advanced for the second stage: (1) a bidentate linkage is formed between an acidic aluminum and two oxygen atoms of an acetal unit (-O-CF 2-O-) of Fomblin Z chains, and (2) the partial positive charge thus developed at the acetal carbon induces a fluorine atom transfer from the adjacent CF 2 unit onto the acetal carbon and results in chain scission with transformation of the acetal sector into a methoxy end-group (-O-CF 3) and the adjacent unit into either an acylfluoride end-group (FCO-CF 2-), or a fluoroformate end-group (FCO-O-CF 2-). Lacking acetal units Krytox and Demnum are stable against this degradation process. In the case of Fomblin Y, owing to the paucity of acetal units, no reaction was observed when heated in the presence of Al 2O 3; when heated with AlCl 3, removal of acetal units and consequential formation of functional end-groups were observed.

  7. 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

  8. Molecular dynamics simulations of the nano-scale room-temperature oxidation of aluminum single crystals

    NASA Astrophysics Data System (ADS)

    Hasnaoui, A.; Politano, O.; Salazar, J. M.; Aral, G.; Kalia, R. K.; Nakano, A.; Vashishta, P.

    2005-03-01

    The oxidation of aluminum single crystals is studied using molecular dynamics (MD) simulations with dynamic charge transfer between atoms. The simulations are performed on three aluminum low-index surfaces ((1 0 0), (1 1 0) and (1 1 1)) at room temperature. The results show that the oxide film growth kinetics is independent of the crystallographic orientation under the present conditions. Beyond a transition regime (100 ps) the growth kinetics follow a direct logarithmic law and present a limiting thickness of ˜3 nm. The obtained amorphous structure of the oxide film has initially Al excess (compared to the composition of Al 2O 3) and evolves, during the oxidation process, to an Al percentage of 45%. We observe also the presence of an important mobile porosity in the oxide. Analysis of atomistic processes allowed us to conclude that the growth proceeds by oxygen atom migration and, to a lesser extent, by aluminum atoms migration. In both cases a layer-by-layer growth mode is observed. The results are in good agreement with both experiments and earlier MD simulations.

  9. 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

  10. 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

  11. Role of atomic layer deposited aluminum oxide as oxidation barrier for silicon based materials

    SciTech Connect

    Fiorentino, Giuseppe Morana, Bruno; Forte, Salvatore; Sarro, Pasqualina Maria

    2015-01-15

    In this paper, the authors study the protective effect against oxidation of a thin layer of atomic layer deposited (ALD) aluminum oxide (Al{sub 2}O{sub 3}). Nitrogen doped silicon carbide (poly-SiC:N) based microheaters coated with ALD Al{sub 2}O{sub 3} are used as test structure to investigate the barrier effect of the alumina layers to oxygen and water vapor at very high temperature (up to 1000 °C). Different device sets have been fabricated changing the doping levels, to evaluate possible interaction between the dopants and the alumina layer. The as-deposited alumina layer morphology has been evaluated by means of AFM analysis and compared to an annealed sample (8 h at 1000 °C) to estimate the change in the grain structure and the film density. The coated microheaters are subjected to very long oxidation time in dry and wet environment (up to 8 h at 900 and 1000 °C). By evaluating the electrical resistance variation between uncoated reference devices and the ALD coated devices, the oxide growth on the SiC is estimated. The results show that the ALD alumina coating completely prevents the oxidation of the SiC up to 900 °C in wet environment, while an oxide thickness reduction of 50% is observed at 1000 °C compared to uncoated devices.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 395-nm and 790-nm femtosecond laser ablation of aluminum-doped zinc oxide

    NASA Astrophysics Data System (ADS)

    Okoshi, Masayuki; Higashikawa, Kouji; Hanabusa, Mitsugu

    2000-11-01

    We used 395-nm and 790-nm femtosecond laser pulses to deposit aluminum-doped zinc oxide films by pulsed laser deposition. Electrical resistivity of the films was lowered (5.6 x 104(Omega) cm) at 200 degree(s)C for the 395-nm laser pulses, while maintaining the optical transparency. In addition, the deposition rate increased six times. Optical emission was measured to compare the plumes generated by 395-nm and 790-nm laser pulses. We found that the emission from ions was suppressed relative to neutral atoms. Also the kinetic energy of ejected species was nearly doubled for the 395-nm laser pulses.

  17. 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.

  18. The effect of surface oxide layer on the rate of hydrogen emission from aluminum and its alloys in a high vacuum

    NASA Technical Reports Server (NTRS)

    Makarova, V. I.; Zyabrev, A. A.

    1979-01-01

    The influence of surface oxide layers on the kinetics of hydrogen emission at the high vacuum of 10 to the minus 8th power torr was investigated at temperatures from 20 to 450 C using samples of pure AB00 aluminum and the cast alloy AMg. Cast and deformed samples of AMts alloy were used to study the effect of oxide film thickness on the rate of hydrogen emission. Thermodynamic calculations of the reactions of the generation and dissociation of aluminum oxide show that degasification at elevated temperatures (up to 600 C) and high vacuum will not reduce the thickness of artificially-generated surface oxide layers on aluminum and its alloys.

  19. 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.

  20. 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.

  1. Thick film fabrication of aluminum nitride microcircuits. Final report

    SciTech Connect

    Perdieu, L.H.

    1994-03-01

    A new substrate material, aluminum nitride (AlN), and 11 new thick film inks were analyzed to determine their chemical compatibility, their electrical properties, their mechanical properties, and their overall suitability for use in the manufacturing of high-power microcircuits with efficient thermal properties. Because high-power chips emit a great deal of heat in a small surface area, a new substrate material was needed to dissipate that heat faster than the substrate material currently in use. Overall, the new materials were found to be acceptable for accomplishing this purpose.

  2. Low temperature aluminum nitride thin films for sensory applications

    SciTech Connect

    Yarar, E.; Zamponi, C.; Piorra, A.; Quandt, E.; Hrkac, V.; Kienle, L.

    2016-07-15

    A low-temperature sputter deposition process for the synthesis of aluminum nitride (AlN) thin films that is attractive for applications with a limited temperature budget is presented. Influence of the reactive gas concentration, plasma treatment of the nucleation surface and film thickness on the microstructural, piezoelectric and dielectric properties of AlN is investigated. An improved crystal quality with respect to the increased film thickness was observed; where full width at half maximum (FWHM) of the AlN films decreased from 2.88 ± 0.16° down to 1.25 ± 0.07° and the effective longitudinal piezoelectric coefficient (d{sub 33,f}) increased from 2.30 ± 0.32 pm/V up to 5.57 ± 0.34 pm/V for film thicknesses in the range of 30 nm to 2 μm. Dielectric loss angle (tan δ) decreased from 0.626% ± 0.005% to 0.025% ± 0.011% for the same thickness range. The average relative permittivity (ε{sub r}) was calculated as 10.4 ± 0.05. An almost constant transversal piezoelectric coefficient (|e{sub 31,f}|) of 1.39 ± 0.01 C/m{sup 2} was measured for samples in the range of 0.5 μm to 2 μm. Transmission electron microscopy (TEM) investigations performed on thin (100 nm) and thick (1.6 μm) films revealed an (002) oriented AlN nucleation and growth starting directly from the AlN-Pt interface independent of the film thickness and exhibit comparable quality with the state-of-the-art AlN thin films sputtered at much higher substrate temperatures.

  3. 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.

  4. 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.

  5. The Electrical Properties of Native and Deposited Thin Aluminum Oxide Layers on Aluminum: Hydration Effects

    SciTech Connect

    Barbour, J.C.; Copeland, R.G.; Dunn, R.G.; Missert, N.; Montes, L.P.; Son, K.-A.; Sullivan, J.P.

    1998-11-11

    The electronic defect density of native, anodic, and synthetic Al oxide layers on Al were studied by solid state electrical measurement as a function of hydration OF the oxide. The non-hydrated synthetic Al oxide layers, which included electron cyclotron resonance (ECR) plasma deposited oxides as well as ECR plasma grown oxides, were highly insulating with electrical transport dominated by thermal emission from deep traps within the oxide. Following hydration these oxides and the native oxides exhibited a large increase in electronic defect density as evidenced by increases in the DC leakage current, reduction in the breakdown field, and increase in AC conductance. Elastic recoil detection of hydrogen revealed that hydration leads to hydrogen incorporation in the oxide films and hydrogen injection through the films into the Al layer below. The increase in electronic defect concentration is related to this hydrogenation and may play a significant role in localized corrosion initiation.

  6. 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

  7. Low-pressure and atmospheric pressure plasma polymerized silica-like films as primers for adhesive bonding of aluminum

    NASA Astrophysics Data System (ADS)

    Gupta, Munish

    2007-12-01

    Plasma processes, including plasma etching and plasma polymerization, were investigated for the pretreatment of aluminum prior to structural adhesive bonding. Since native oxides of aluminum are unstable in the presence of moisture at elevated temperature, surface engineering processes must usually be applied to aluminum prior to adhesive bonding to produce oxides that are stable. Plasma processes are attractive for surface engineering since they take place in the gas phase and do not produce effluents that are difficult to dispose off. Reactive species that are generated in plasmas have relatively short lifetimes and form inert products. The objective of this work was to develop plasma etching and plasma polymerization as environmentally compatible processes for surface engineering of aluminum. Plasma polymerized silica-like films of thickness less than 200 nm were deposited on pretreated aluminum substrates using hexamethyldisiloxane (HMDSO) as the "monomer" and oxygen as a "co-reactant" in low-pressure RF-powered (13.6 MHz) reactor. Recently, plasma deposition at atmospheric pressure has become a promising technology because they do not require vacuum systems, can be applied to large objects with complex shapes, and adapted easily for continuous processing. Therefore, atmospheric pressure plasma processes were investigated and compared with their more traditional counterparts, low-pressure plasmas. Molecular structure and morphology of the plasma polymerized films were determined using surface analysis techniques such as X-ray photoelectron spectroscopy (XPS), fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The effectiveness of plasma etching and plasma polymerization as surface engineering processes for aluminum were probed by determining the initial strength and durability of aluminum/epoxy lap joints prepared from substrates that were plasma pretreated, coated with silica-like film, and

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. Synthesis and improved explosion behaviors of aluminum powders coated with nano-sized nickel film

    NASA Astrophysics Data System (ADS)

    Kim, Kyung Tae; Kim, Dong Won; Kim, Soo Hyung; Kim, Chang Kee; Choi, Yoon Jeong

    2017-09-01

    Nickel (Ni) materials with a thickness of a few hundred nm were homogeneously coated on the surfaces of aluminum (Al) powders by an electroless plating process. The Ni-coated Al powders show characteristic interfacial structures mixed of Ni, Al and O instead of densely packed Al oxide at the surface. The explosion test of the Ni-coated Al powders utilizing flame ignition showed that the powders had a 3.6 times enhanced pressurization rate of 405 kPa/ms compared to 111 kPa/ms of uncoated Al powders. It was found that this is due to a feasible diffusion of oxygen atoms into the Al powders through the thin and rough interfacial layers present at the Ni/Al interface. These results clearly indicate that nano-sized Ni film introduced instead of surface oxide acts as a very profitable layer to achieve efficient combustion behaviors by a rapid oxidation of Al powders.

  13. Aluminum oxide filler prevents obstructions in tubing during welding

    NASA Technical Reports Server (NTRS)

    Okelly, K. P.

    1966-01-01

    Granular aluminum oxide is used as filler in serpentine tubing while welding the tubing to a flat surface. The filler eliminates obstructions in the tubes formed by molten weld nuggets and is porous enough to allow gases to escape from the welding area.

  14. 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... 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. No...

  15. 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. No...

  16. 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. No...

  17. 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. No...

  18. 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... 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. No...

  19. 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

  20. 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.

  1. 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.

  2. Progress in Nano-Engineered Anodic Aluminum Oxide Membrane Development

    PubMed Central

    Poinern, Gerrard Eddy Jai; Ali, Nurshahidah; Fawcett, Derek

    2011-01-01

    The anodization of aluminum is an electro-chemical process that changes the surface chemistry of the metal, via oxidation, to produce an anodic oxide layer. During this process a self organized, highly ordered array of cylindrical shaped pores can be produced with controllable pore diameters, periodicity and density distribution. This enables anodic aluminum oxide (AAO) membranes to be used as templates in a variety of nanotechnology applications without the need for expensive lithographical techniques. This review article is an overview of the current state of research on AAO membranes and the various applications of nanotechnology that use them in the manufacture of nano-materials and devices or incorporate them into specific applications such as biological/chemical sensors, nano-electronic devices, filter membranes and medical scaffolds for tissue engineering. PMID:28880002

  3. 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.

  4. 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

  5. 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...

  6. 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...

  7. 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.

  8. Piezoelectric actuated micro-resonators based on the growth of diamond on aluminum nitride thin films.

    PubMed

    Hees, J; Heidrich, N; Pletschen, W; Sah, R E; Wolfer, M; Williams, O A; Lebedev, V; Nebel, C E; Ambacher, O

    2013-01-18

    Unimorph heterostructures based on piezoelectric aluminum nitride (AlN) and diamond thin films are highly desirable for applications in micro- and nanoelectromechanical systems. In this paper, we present a new approach to combine thin conductive boron-doped as well as insulating nanocrystalline diamond (NCD) with sputtered AlN films without the need for any buffer layers between AlN and NCD or polishing steps. The zeta potentials of differently treated nanodiamond (ND) particles in aqueous colloids are adjusted to the zeta potential of AlN in water. Thereby, the nucleation density for the initial growth of diamond on AlN can be varied from very low (10(8) cm(-2)), in the case of hydrogen-treated ND seeding particles, to very high values of 10(11) cm(-2) for oxidized ND particles. Our approach yielding high nucleation densities allows the growth of very thin NCD films on AlN with thicknesses as low as 40 nm for applications such as microelectromechanical beam resonators. Fabricated piezo-actuated micro-resonators exhibit enhanced mechanical properties due to the incorporation of boron-doped NCD films. Highly boron-doped NCD thin films which replace the metal top electrode offer Young's moduli of more than 1000 GPa.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. Tailoring oxidation of aluminum nanoparticles reinforced with carbon nanotubes

    SciTech Connect

    Sharma, Manjula; Sharma, Vimal

    2016-05-23

    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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. Mechanistic, surface chemistry, and growth studies of novel precursors for aluminum nitride thin films

    NASA Astrophysics Data System (ADS)

    Robinson, David Walter

    One of the primary techniques for thin film deposition used in the fabrication of microelectronic and optoelectronic devices is chemical vapor deposition (CVD). In CVD, nutrient elements for film growth are transported in the gas phase to the growth surface where a complex series of chemical reactions occurs. The selection of the chemicals and process parameters determines the properties of the film that will be obtained. Aluminum nitride (AlN) is a direct wide bandgap material with excellent physical properties making it useful for a wide variety of solid state device applications. This research focused on (1) screening novel chemicals as viable sources for vapor phase deposition of AlN by investigating their adsorption and decomposition behavior on technologically important substrates, (2) developing growth strategies from these results, (3) implementing the growth strategies, and (4) characterizing the thin films that were deposited. Surface chemistry investigations of four potential AlN CVD sources were conducted. The sources were bis[amidobis(trimethylsilyl)aluminum] (BABTMSA), 1,1-dimethylhydrazine (DMHy), ammonia (NH3), and dimethylethylamine alane (DMEAA). BABTMSA, a potential single source precursor, did not have adsorption properties that allowed for facile decomposition to AlN. DMHy, NH3, and DMEAA all showed adsorption and decomposition behavior on Si(100) under certain conditions that was promising for AIN deposition. A growth strategy was developed for the deposition of AlN thin films at low temperature with minimal impurities employing a temperature modulated atomic layer growth (ALG) process using DMHy and DMEAA precursors. The growth strategy was implemented and investigated. The deposition proceeded primarily through the dehydrogenation of AlHyNHx species where regeneration of these species occurred in each cycle. This was also found to be the primary mechanism for ALG of AlN using DMEAA and NH3 and similar processing conditions. The low

  7. 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.

  8. 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.

  9. Naringin protects memory impairment and mitochondrial oxidative damage against aluminum-induced neurotoxicity in rats.

    PubMed

    Prakash, Atish; Shur, Bhargabi; Kumar, Anil

    2013-09-01

    Aluminum has been indicated in neurodegenerative disorders and naringin, a bioflavonoid has been used to reduce neurotoxic effects of aluminum against aluminum chloride-induced rats. Therefore, present study has been designed to explore the possible role of naringin against aluminum-induced cognitive dysfunction and oxidative damage in rats. Aluminum (100 mg/kg) and naringin (40 and 80 mg/kg) drug treatment were administered orally for six weeks to male wistar rats. Various behavioral performance tasks, biochemical, mitochondrial oxidative parameters, and aluminum concentration in the brain were assessed. Aluminum chloride treatment significantly caused cognitive dysfunction and mitochondria oxidative damage as compared to vehicle treated control group. Besides, aluminum chloride treatment significantly increased acetyl cholinesterase activity and aluminum concentration in the brain as compared to sham. Chronic administration of naringin significantly improved cognitive performance and attenuated mitochondria oxidative damage, acetyl cholinesterase activity, and aluminum concentration in aluminum-treated rats as compared to control rats. Results of the study demonstrate neuroprotective potential of naringin against aluminum chloride-induced cognitive dysfunction and mitochondrial oxidative damage.

  10. Deposition and characterization of aluminum magnesium boride thin film coatings

    NASA Astrophysics Data System (ADS)

    Tian, Yun

    Boron-rich borides are a special group of materials possessing complex structures typically comprised of B12 icosahedra. All of the boron-rich borides sharing this common structural unit exhibit a variety of exceptional physical and electrical properties. In this work, a new ternary boride compound AlMgB14, which has been extensively studied in bulk form due to its novel mechanical properties, was fabricated into thin film coatings by pulsed laser deposition (PLD) technology. The effect of processing conditions (laser operating modes, vacuum level, substrate temperature, and postannealing, etc.) on the composition, microstructure evolution, chemical bonding, and surface morphology of AlMgB14 thin film coatings has been investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectrometry; the mechanical, electrical, and optical properties of AlMgB14 thin films have been characterized by nanoindentation, four-point probe, van der Pauw Hall measurement, activation energy measurement, and UV-VIS-NIR spectrophotometer. Experimental results show that AlMgB14 films deposited in the temperature range of 300 K - 873 K are amorphous. Depositions under a low vacuum level (5 x 10-5 Torr) can introduce a significant amount of C and O impurities into AlMgB14 films and lead to a complex oxide glass structure. Orthorhombic AlMgB14 phase cannot be obtained by subsequent high temperature annealing. By contrast, the orthorhombic AlMgB 14 crystal structure can be attained via high temperature-annealing of AlMgB14 films deposited under a high vacuum level (< 3 x 10-6 Torr), accompanied by strong texture formation. Low vacuum level-as deposited AlMgB14 films have low hardness (10 GPa), but high vacuum level-as deposited AlMgB14 films exhibit an extremely high hardness (45 GPa - 51 GPa), and the higher deposition temperature results in still higher hardness

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. High temperature performance of sputter-deposited piezoelectric aluminum nitride thin films

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    Aluminum nitride (AlN) is a promising material for sensor applications in harsh environments such as turbine exhausts or thermal power plants due to its piezoelectric properties, good thermal match to silicon and high temperature stability. Typically, the usage of piezoelectric materials in high temperature is limited by the Curie-temperature, the increase of the leakage current as well as by enhanced diffusion effects in the materials. In order to exploit the high temperature potential of AlN thin films, post deposition annealing experiments up to 1000°C in both oxygen and nitrogen gas atmospheres for 2 h were performed. X-ray diffraction measurements indicate that the thin films are chemically stable in a pure oxygen atmosphere for 2 h at annealing temperatures of up to 900°C. After a 2 h annealing step at 1000°C in pure oxygen. However, a 100 nm thin AlN film is completely oxidized. In contrast, the layer is stable up to 1000°C in pure nitrogen atmosphere. The surface topology changes significantly at annealing temperatures above 800°C independent of annealing atmosphere. The surface roughness is increased by about one order of magnitude compared to the "as deposited" state. This is predominantly attributed to recrystallization processes occurring during high temperature loading. Up to an annealing temperature of 700°C, a Poole-Frenkel conduction mechanism dominates the leakage current characteristics. Above, a mixture of different leakage current mechanisms is observed.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Differential responses of oat genotypes: oxidative stress provoked by aluminum.

    PubMed

    Pereira, Luciane Belmonte; de A Mazzanti, Cinthia Melazzo; Cargnelutti, Denise; Rossato, Liana Verônica; Gonçalves, Jamile F; Calgaroto, Nicéia; Dressler, Valderi; Nicoloso, Fernando T; Federizzi, Luiz Carlos; Morsch, Vera M; Schetinger, Maria R C

    2011-02-01

    The phytotoxic effects of aluminum and the mechanisms of genetically-based Al tolerance have been widely investigated, as reported in many papers and reviews. However, investigations on many Al-sensitive and Al-resistant species demonstrate that Al phytotoxicity and Al-resistance mechanisms are extremely complex phenomena. The objective of the present study was to analyze the effects of aluminum on the activity of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX). Also was evaluated the lipid peroxidation, H(2)O(2) content, levels of ascorbic acid (ASA), non-protein thiols (NPSH) and Al content in three genotypes of oat, Avena sativa L. (UFRGS 930598, UFRGS 17, and UFRGS 280). The genotypes were grown in different concentrations of Al ranging from 90 to 555 μM for 5 days. The antioxidant system was unable to overcome toxicity resulting in negative effects such as lipid peroxidation and H(2)O(2) content in UFRGS 930598. The results showed that UFRGS 930598 was the most sensitive genotype. UFRGS 17 and UFRGS 280 were more resistant to Al toxicity. These results suggest that UFRGS 17 has mechanisms of external detoxification and UFRGS 280 has mechanisms of internal detoxification. The different behavior of enzymatic and non-enzymatic antioxidants of the genotypes showed that aluminum resistance in UFGRS 17 and UFRGS 280 may be related to oxidative stress.

  2. 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.

  3. 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.

  4. Thermal emissivity and solar absorptivity of aluminum coated with double layers of aluminum oxide and silicon oxide.

    PubMed

    Hass, G; Ramsey, J B; Heaney, J B; Triolo, J J

    1971-06-01

    A technique using evaporated Al coated with double layers of Al(2)O(3) and silicon oxide to produce surface films having low solar absorptivity (alpha) and high total normal and hemispherical emissivities (epsilonN and epsilon) is described. High vacuum evaporation with an electron gun was used for preparing undecomposed films of Al(2)O(3) and SiO(2). alpha and epsilonN were determined from reflectance measurements made in the wavelength region from 0.2micro to 50micro. epsilon was measured calorimetrically by a transient thermal method. alpha of all Al + Al(2)O(3) + silicon oxide film combinations was determined to be about 0.12. The greatest increase in epsilonN and epsilon was obtained when Al was first coated with Al(2)O(3) about lambda/4 thick at 10micro and then overcoated with 2000 A to 4000 A of silicon oxide. With such film combinations alpha/epsilon values of less than 0.2 could be readily achieved. Surface films of this type were found to be extremely stable during simulated solar uv irradiation.

  5. 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."

  6. 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.

  7. 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.

  8. 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.

  9. 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).

  10. 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.

  11. 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.

  12. 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.

  13. 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.}

  14. 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.

  15. 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.

  16. 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.

  17. Investigation of surface oxides on aluminum alloys by valence band photoemission

    NASA Astrophysics Data System (ADS)

    Claycomb, Gregory D.; Sherwood, Peter M. A.

    2002-07-01

    Core level and valence band x-ray photoelectron spectroscopy are used to study the chemical composition of the surface films on aluminum alloys. Certain alloying elements may preferentially migrate to the surface of an alloy, thereby altering the composition and consequently the chemistry of the surface. The behavior of a 6061 aluminum alloy is compared with that of pure aluminum. It is shown that the type of magnesium film formed at the alloy surface can be determined by comparing the valence band spectra of the aluminum alloy surface with that of known magnesium and aluminum compounds. The experimental valence band spectra of these compounds are supported by spectra generated from band structure calculations. The effect of boiling water on the surface film is discussed, with significant differences in surface chemistry being seen for the metal and the alloy. copyright 2002 American Vacuum Society.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. Astaxanthin ameliorates aluminum chloride-induced spatial memory impairment and neuronal oxidative stress in mice.

    PubMed

    Al-Amin, Md Mamun; Reza, Hasan Mahmud; Saadi, Hasan Mahmud; Mahmud, Waich; Ibrahim, Abdirahman Adam; Alam, Musrura Mefta; Kabir, Nadia; Saifullah, A R M; Tropa, Sarjana Tarannum; Quddus, A H M Ruhul

    2016-04-15

    Aluminum chloride induces neurodegenerative disease in animal model. Evidence suggests that aluminum intake results in the activation of glial cells and generation of reactive oxygen species. By contrast, astaxanthin is an antioxidant having potential neuroprotective activity. In this study, we investigate the effect of astaxanthin on aluminum chloride-exposed behavioral brain function and neuronal oxidative stress (OS). Male Swiss albino mice (4 months old) were divided into 4 groups: (i) control (distilled water), (ii) aluminum chloride, (iii) astaxanthin+aluminum chloride, and (iv) astaxanthin. Two behavioral tests; radial arm maze and open field test were conducted, and OS markers were assayed from the brain and liver tissues following 42 days of treatment. Aluminum exposed group showed a significant reduction in spatial memory performance and anxiety-like behavior. Moreover, aluminum group exhibited a marked deterioration of oxidative markers; lipid peroxidation (MDA), nitric oxide (NO), glutathione (GSH) and advanced oxidation of protein products (AOPP) in the brain. To the contrary, co-administration of astaxanthin and aluminum has shown improved spatial memory, locomotor activity, and OS. These results indicate that astaxanthin improves aluminum-induced impaired memory performances presumably by the reduction of OS in the distinct brain regions. We suggest a future study to determine the underlying mechanism of astaxanthin in improving aluminum-exposed behavioral deficits. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. 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.

  4. 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.

  5. Electrochromism in copper oxide thin films

    SciTech Connect

    Richardson, T.J.; Slack, J.L.; Rubin, M.D.

    2000-08-15

    Transparent thin films of copper(I) oxide prepared on conductive SnO2:F glass substrates by anodic oxidation of sputtered copper films or by direct electrodeposition of Cu2O transformed reversibly to opaque metallic copper films when reduced in alkaline electrolyte. In addition, the same Cu2O films transform reversibly to black copper(II) oxide when cycled at more anodic potentials. Copper oxide-to-copper switching covered a large dynamic range, from 85% and 10% photopic transmittance, with a coloration efficiency of about 32 cm2/C. Gradual deterioration of the switching range occurred over 20 to 100 cycles. This is tentatively ascribed to coarsening of the film and contact degradation caused by the 65% volume change on conversion of Cu to Cu2O. Switching between the two copper oxides (which have similar volumes) was more stable and more efficient (CE = 60 cm2/C), but covered a smaller transmittance range (60% to 44% T). Due to their large electrochemical storage capacity and tolerance for alkaline electrolytes, these cathodically coloring films may be useful as counter electrodes for anodically coloring electrode films such as nickel oxide or metal hydrides.

  6. 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

  7. Surface composition of solid-rocket exhausted aluminum oxide particles

    NASA Technical Reports Server (NTRS)

    Cofer, Wesley R., III; Winstead, Edward L.; Key, Lawrence E.

    1989-01-01

    Particulate samples of aluminum oxide were collected on Teflon filters from the exhaust plume of the Space Shuttle (STS-61A, October 30, 1985) over the altitude interval 4.6-7.6 km immediately after launch. These particles were analyzed using SEM, energy-dispersive X-ray analysis, electron spectroscopy for chemical analysis, X-ray fluorescent spectroscopy, and conventional wet-chemical techniques. The samples were 0.6-1.0 percent surface-chlorided (chlorided meaning predominantly aluminum chlorides and oxychlorides, possibly including other adsorbed forms of chloride) by weight. This level of chloriding is about one-third of the amount determined previously from laboratory-prepared alumina and surface site samples of solid-rocket-produced alumina (SRPA) after both had been exposed to moist HCl vapor at temperatures down to ambient. This level is equivalent to previous laboratory results with samples exposed to moist HCl at temperatures above the boiling point of water. It is suggested that the present lower chloriding levels, determined for samples from a 'dry' Shuttle exhaust cloud, underscore the importance of a liquid water/hydrochloric acid phase in governing the extent of surface chloriding of SRPA. The reduced chloriding is not trivial with respect to potential physical/chemical modification of the SRPA particle surfaces and their corresponding interaction with the atmosphere.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Fano resonance in anodic aluminum oxide based photonic crystals.

    PubMed

    Shang, Guo Liang; Fei, Guang Tao; Zhang, Yao; Yan, Peng; Xu, Shao Hui; Ouyang, Hao Miao; Zhang, Li De

    2014-01-08

    Anodic aluminum oxide based photonic crystals with periodic porous structure have been prepared using voltage compensation method. The as-prepared sample showed an ultra-narrow photonic bandgap. Asymmetric line-shape profiles of the photonic bandgaps have been observed, which is attributed to Fano resonance between the photonic bandgap state of photonic crystal and continuum scattering state of porous structure. And the exhibited Fano resonance shows more clearly when the sample is saturated ethanol gas than air-filled. Further theoretical analysis by transfer matrix method verified these results. These findings provide a better understanding on the nature of photonic bandgaps of photonic crystals made up of porous materials, in which the porous structures not only exist as layers of effective-refractive-index material providing Bragg scattering, but also provide a continuum light scattering state to interact with Bragg scattering state to show an asymmetric line-shape profile.

  13. 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.

  14. 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.

  15. 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.

  16. Pretreatment effects on the morphology and properties of aluminum oxide thermally grown on NiCoCrAlY

    NASA Technical Reports Server (NTRS)

    Prakash, S.; Budhani, R.; Doerr, H. J.; Deshpandey, C. V.; Bunshah, R. F.

    1985-01-01

    The effect of pretreatments on the morphology and properties of aluminum oxide thermally grown from NiCoCrAlY was investigated. The goal was to optimize process steps to produce a highly adherent, continuous, and insulating aluminum oxide. Two pretreatments were carried out, one in vacuum (about 0.0001 Torr) at 1350 K for 5 h, and the other consisting of deposition of a 1-micron thick Al2O3 film by activated reactive evaporation. Samples were subsequently oxidized thermally at 1000 C for 50 h at 0.5 Torr oxygen pressure. The two pretreatments were carried out on electron-beam evaporation NiCoCrAlY, about 120 microns thick, deposited on a superalloy turbine blade substrate. The results showed that the thermally grown oxide was significantly different in microstructure, surface topography and in its adherence to the NiCoCrAlY for the two pretreatments. Optimum results were obtained by combining the two pretreatments to produce an adherent, continuous, and insulating oxide film on the NiCoCrAlY-coated superalloy substrate.

  17. 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.

  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. Orchiectomy attenuates oxidative stress induced by aluminum in rats.

    PubMed

    Contini, María Del Carmen; Millen, Néstor; González, Marcela; Benmelej, Adriana; Fabro, Ana; Mahieu, Stella

    2016-08-01

    The aim of this work was to study whether the increase in antioxidant defenses associated with orchiectomy may account for the reduced susceptibility to aluminum (Al) in male kidney and also to examine whether the reduced antioxidant defenses are associated with androgen levels in orchiectomized (ORX) rats treated with testosterone propionate (TP). Rats were divided into nine groups, namely, intact males (without treatment, treated with sodium lactate, and treated with Al), sham males, ORX males (without treatment, treated with sodium lactate, treated with TP, treated with Al, and treated with TP and Al). Al groups were chronically treated with aluminum lactate for 12 weeks (0.575 mg Al/100 g of body weight, intraperitoneally, three times per week). We reported that ORX rats treated with Al had significantly less lipid peroxidation and an increased level of reduced glutathione (GSH) and GSH/oxidized glutathione ratio in the kidney when compared with intact and TP-treated ORX rats. The activity of superoxide dismutase, catalase, and glutathione peroxidase in ORX rats was much greater than in intact or TP-administered ORX rats. Castration reduced the glomerular alterations caused by Al as well as the number of necrotic tubular cells and nuclear abnormalities. However, we observed a slight alteration in brush border, dilation of proximal tubules, mononuclear infiltrates, and interstitial fibrosis. Castrated males treated with TP showed that this intervention cancels the protective effect of the ORX. This finding suggests that androgens contribute to the development of renal alterations and proteinuria in rats treated with Al. Our results showed that ORX rats are protected against the induction of oxidative stress by Al, but the morphological damage to the kidney tissue induced by the cation was only reduced. Male intact rats treated with Al had more severe glomerulosclerosis, tubular damage, and proteinuria than ORX rats. © The Author(s) 2015.

  20. 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.

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

    PubMed Central

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

    2013-01-01

    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. PMID:23682201

  2. 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.

  3. Fabrication and characterization of nano porous lattice biosensor using anodic aluminum oxide substrate

    NASA Astrophysics Data System (ADS)

    Ito, Takeshi; Matsuda, Yuki; Jinba, Takatoshi; Asai, Naoto; Shimizu, Tomohiro; Shingubara, Shoso

    2017-06-01

    Localized surface plasmon resonance (LSPR) attracts attention for the fabrication of a biosensor because it can be used easily and is highly sensitive to the change in surface reflective index. Anodic aluminum oxide (AAO) has self-assembled nanoholes and is fabricated easily all over the Al substrate. The depth and diameter of the nanoholes are easily controlled by changing the etching solution and applied voltage. By depositing a Au thin film on the AAO substrate, the sensitivity of the sensor chip was affected by both optical interference and LSPR. In this study, the optical property of the AAO-based LSPR sensor chip was characterized on the basis of the nanostructure. We presented a biosensing application of the AAO-based LSPR sensor chip. The highest sensitivity of the sensor chip was observed at the AAO nanohole diameter of 75 nm and the AAO nanohole depth of 0.5 µm, when bovine serum albumin (BSA) adsorbed on the sensor chip.

  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. 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

  6. 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.

  7. Fracture Analysis of MWCNT/Epoxy Nanocomposite Film Deposited on Aluminum Substrate

    PubMed Central

    Her, Shiuh-Chuan; Chien, Pao-Chu

    2017-01-01

    Multi-walled carbon nanotube (MWCNT) reinforced epoxy films were deposited on an aluminum substrate by a hot-pressing process. Three-point bending tests were performed to determine the Young’s modulus of MWCNT reinforced nanocomposite films. Compared to the neat epoxy film, nanocomposite film with 1 wt % of MWCNT exhibits an increase of 21% in the Young’s modulus. Four-point-bending tests were conducted to investigate the fracture toughness of the MWCNT/epoxy nanocomposite film deposited on an aluminum substrate with interfacial cracks. Based on the Euler-Bernoulli beam theory, the strain energy in a film/substrate composite beam is derived. The difference of strain energy before and after the propagation of the interfacial crack are calculated, leading to the determination of the strain energy release rate. Experimental test results show that the fracture toughness of the nanocomposite film deposited on the aluminum substrate increases with the increase in the MWCNT content. PMID:28772768

  8. 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.

  9. 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.

  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. FePt nano-stripes fabricated on anodic aluminum oxide templates

    NASA Astrophysics Data System (ADS)

    Deng, Chen-Hua; Qiao, Xin-Yu; Wang, Fang; Fan, Jiu-Ping; Zeng, Hao; Xu, Xiao-Hong

    2015-07-01

    A new FePt nanostructure with stripe-like patterns has been prepared by direct current (DC) magnetron sputtering on anodic aluminum oxide (AAO) templates. AAO templates anodized under low voltages (7 V) demonstrate self-organized, maze-like patterns, different from the conventional porous structures obtained at high voltages. FePt thin films deposited on such templates tend to replicate the morphology of the templates. Although there is no obvious spatial ordering, the dimensions of the FePt nano-stripes are highly uniform, due to the constrained growth along the transverse direction of the AAO pattern. The magnetic properties are strongly influenced by this unique morphology. While continuous films demonstrate strong exchange coupling, the dominant interaction in FePt nano-stripes with the same nominal thickness is magnetostatic. The morphology also dictates the magnetization reversal behaviors, with thin films dominated by domain nucleation; while nano-stripes incline to reverse their magnetization by spin rotation. Our work demonstrates that self-organized AAO templates can be used to control the morphology and magnetic behavior of FePt materials. Project supported by the National Natural Science Foundation of China (Grant Nos. 51025101, 51101095, 61434002, 11274214, and 51301099) and the Program of “One Hundred Talented People” of Shanxi Province, China.

  12. Oxide Film and Porosity Defects in Magnesium Alloy AZ91

    SciTech Connect

    Wang, Liang; Rhee, Hongjoo; Felicelli, Sergio D.; Sabau, Adrian S; Berry, John T.

    2009-01-01

    Porosity is a major concern in the production of light metal parts. This work aims to identify some of the mechanisms of microporosity formation in magnesium alloy AZ91. Microstructure analysis was performed on several samples obtained from gravity-poured ingots in graphite plate molds. Temperature data during cooling was acquired with type K thermocouples at 60 Hz at three locations of each casting. The microstructure of samples extracted from the regions of measured temperature was then characterized with optical metallography. Tensile tests and conventional four point bend tests were also conducted on specimens cut from the cast plates. Scanning electron microscopy was then used to observe the microstructure on the fracture surface of the specimens. The results of this study revealed the existence of abundant oxide film defects, similar to those observed in aluminum alloys. Remnants of oxide films were detected on some pore surfaces, and folded oxides were observed in fracture surfaces indicating the presence of double oxides entrained during pouring.

  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. 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.

  15. [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.

  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. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Microtribological Mechanisms of Tungsten and Aluminum Nitride Films

    NASA Astrophysics Data System (ADS)

    Zhao, Hongjian; Mu, Chunyan; Ye, Fuxing

    2016-04-01

    Microtribology experiments were carried out on the W1- x Al x N films, deposited by radio frequency magnetron reactive sputtering on 304 stainless steel substrates and Si(100). Film wear mechanisms were investigated from the evolution of the friction coefficient and scanning electron microscopy observations. The results show that the WAlN films consist of a mixture of face-centered cubic W(Al)N and hexagonal wurtzite structure AlN phases and the preferred orientation changes from (111) to (200). The film damage after sliding test is mainly attributed to the composition and microstructure of the films. The amount of debris generated by friction is linked to the crack resistance. The better tribological properties for W1- x Al x N films ( x < 0.4) are mainly determined by the higher toughness.

  2. 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.

  3. 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.

  4. In-process oxidation protection in fluxless brazing or diffusion bonding of aluminum alloys

    NASA Technical Reports Server (NTRS)

    Okelly, K. P.; Featherston, A. B.

    1974-01-01

    Aluminum is cleaned of its oxide coating and is sealed immediately with polymeric material which makes it suitable for fluxless brazing or diffusion bonding. Time involved between cleaning and brazing is no longer critical factor.

  5. Direct deposition of highly conductive aluminum thin film on substrate by solution-dipping process.

    PubMed

    Lee, Hye Moon; Choi, Si-Young; Jung, Areum

    2013-06-12

    A solution-dipping process consisting of 2 steps, including (i) a catalytic treatment of the substrate and (ii) an immersion of the catalytically treated substrate into an aluminum precursor solution of AlH3{O(C4H9)2}, is suggested for the low-cost and simple preparation of aluminum thin film. This process can be applied to electric devices in the way of not only various film geometry including large area (□ 100 mm (W) × 100 mm (L)) or patterned structure but also the diverse substrate selectivity including rigid or flexible substrate. More interestingly, preparations of aluminum film in this study can be unprecedentedly accomplished at room temperature with the help of chemical catalyst to decompose AlH3{O(C4H9)2} into Al, 1.5H2, and O(C4H9)2. Beyond the previously reported processes, the prepared Al films via solution-dipping process are comparable or even superior to Ag, Au, and Al films prepared by other solution processes and furthermore are found to be excellent in mechanical durability against external deformation.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. The development of a preliminary correlation of data on oxide growth on 6061 aluminum under ANS thermal-hydraulic conditions

    SciTech Connect

    Pawel, R.E.; Yoder, G.L.; West, C.D.; Montgomery, B.H.

    1990-06-01

    The corrosion of aluminum alloy 6061 is being studied in a special test loop facility under the range of thermal-hydraulic conditions appropriate for fuel plate operation in the Advanced Neutron Source (ANS) reactor core. Experimental measurements describing the growth of the boehmite (Al{sub 2}O{sub 3}H{sub 2}O) films on the exposed aluminum surfaces are now available for a range of coolant conditions and heat fluxes, and these results have been analyzed to demonstrate the influence of several important experimental variables. A subset of our data base particularly appropriate to the ANS conditions presently anticipated was used to develop a preliminary correlation based on an empirical oxidation model.

  12. Zero-Direct-Carbon-Emission Aluminum Production by Solid Oxide Membrane-Based Electrolysis Process

    NASA Astrophysics Data System (ADS)

    Su, Shizhao; Pal, Uday; Guan, Xiaofei

    A zero-direct-carbon-emission solid oxide membrane (SOM) electrolysis process was designed and developed to produce high purity aluminum metal. An inert anode assembly containing liquid silver in a one-end-closed YSZ (yttria-stabilized zirconia) membrane tube and LSM (La0.8Sr0.2MnO3-δ)-Inconel inert anode current collector was immersed in an alumina containing molten fluoride flux. A proof-of-concept electrolysis experiment was performed to confirm the aluminum production by depositing liquid aluminum directly on a TiB2 cathode. An improved setup employing liquid aluminum cathode was subsequently used to produce high purity aluminum using the SOM electrolysis process. The membrane stability was confirmed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. High purity aluminum (>99wt%) was produced and collected after the electrolysis.

  13. Investigation of electrodeposited cuprous oxide thin films

    NASA Astrophysics Data System (ADS)

    Mortensen, Emma L.

    This dissertation focuses on improvements to electrodeposited cuprous oxide as a candidate for the absorber layer for a thin film solar cell that could be integrated into a mechanical solar cell stack. Cuprous oxide (Cu2O) is an earth abundant material that has a bandgap of 2 eV with absorption coefficients around 102-106 cm-1. This bandgap is not optimized for use as a single-junction solar cell, but could be ideal for use in a tandem solar cell device. The theoretical efficiency of a material with a bandgap of 2.0 eV is 20%. The greatest actual efficiency that has been achieved for a Cu2O solar cell is only 8.1%. For the present work the primary focus has been on improving the microstructure of the absorber layer film. The Cu2O films were fabricated using electrodeposition. A seeding layer was developed using gold (Au); which was manipulated into nano-islands and used as the substrate for the Cu2O electrodeposition. The films were characterized and compared to determine the growth mechanism of each film using scanning electron microscopy (SEM). X-ray diffraction (XRD) was used to establish and compare the chemical phases that were present in each of the films. The crystal structure of the Cu2O film grown on gold was explored using transmission electron microscopy (TEM), and this helped confirm the effect that the gold had on the growth of Cu2O. The Tauc method was then used to determine the bandgap of the films of Cu2O grown on both substrates and this showed that the Au based Cu2O film was a superior film. Electrical tests were also completed using a solar simulator and this established that the film grown on gold exhibited photoconductivity that was not seen on the film without gold. In addition, for this thesis, a method for depositing an n-type Cu2O film, based on a Cu-metal solution-boiling process, was investigated. Three forms of copper were tested: a sheet of copper, electrodeposited copper, and sputtered copper. The chemical phases were observed using

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Structural properties of aluminum-nitrogen films prepared at low temperature

    NASA Astrophysics Data System (ADS)

    Ribeiro, C. T. M.; Alvarez, F.; Zanatta, A. R.

    2002-08-01

    Aluminum-nitrogen thin films have been obtained under well-controlled conditions by ion-beam-assisted deposition (IBAD). The films were deposited on crystalline silicon and sapphire substrates at relative low temperature (approx325 K). Taking advantage of the ion energy control provided by the IBAD technique, the films were prepared with N2+ ions with energies ranging from 100 to 300 eV. After deposition, the films were investigated by in situ x-ray photoelectron spectroscopy, ex situ by optical spectroscopy, and x-ray diffraction. Detailed Raman scattering measurements in the 100-2500 cm-1 wave number range were also performed revealing interesting features related to the atomic composition and structure of the films. The Raman data suggest that a misidentification of some vibration modes can lead to incorrect interpretations of the crystalline quality of aluminum-nitrogen films. Finally, the results indicate the suitability of IBAD to produce crystalline AlN films at considerably lower temperatures.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. Excimer laser induced photolytic deposition of aluminum nitride: Film growth and properties

    SciTech Connect

    Radhakrishnan, G.; Adams, P.M.; Marquez, N.

    1996-12-31

    Excimer laser photolysis has been used for the growth of smooth and well-adhering thin films of aluminum nitride (AlN) on Si, fused quartz, and KBr substrates at temperatures as low as 350 K. The photolysis was carried out at 193 nm, with the laser beam propagating parallel to the substrate. Trimethylamine alane and ammonia were used as gas-phase precursors. The growth rate of these films was investigated as a function of laser fluence. These measurements, as well as other investigations of film growth with and without the photolysis laser, reveal that no AlN film is produced in the absence of laser-induced photolysis of the precursors. The morphology and physical properties of these laser-grown films have been studied by scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. Optical absorption spectra of films grown on fused quartz were measured as a function of substrate temperature. A substrate temperature of 350 K was found to be optimum for obtaining good film quality while precluding any effects due to the thermal decomposition of the precursors. The films have excellent dielectric properties as shown by I-V and C-V measurements. The details of AlN film growth using low-temperature gas-phase photolysis at 193 nm and the characterization of these laser grown films will be discussed.

  11. 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

  12. Comparison of the synthesis of Ge nanocrystals in hafnium aluminum oxide and silicon oxide matrices.

    PubMed

    Chew, H G; Zheng, F; Choi, W K; Chim, W K; Fitzgerald, E A; Foo, Y L

    2009-02-01

    Growth of germanium (Ge) nanocrystals in silicon (Si) oxide and hafnium aluminum oxide (HfAlO) is examined. In Si oxide, nanocrystals were able to form at annealing temperatures of 800 degrees C to 1000 degrees C. Nanocrystals formed at 800 degrees C were round and approximately 8 nm in diameter, at 900 degrees C they become facetted and at 1000 degrees C they become spherical again. In HfAlO, at 800 degrees C nanocrystals formed are relatively smaller (approximately 3 nm in diameter) and lower in density. While at 900 degrees C and 1000 degrees C, nanocrystals did not form due to out-diffusion of Ge. Different nanocrystal formation characteristics in the matrices are attributed to differences in their crystallization temperatures.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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,...

  20. 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,...

  1. Structural, optical and electrical properties of yttrium-doped hafnium oxide nanocrystalline thin films

    NASA Astrophysics Data System (ADS)

    Kongu, Abhilash

    Hafnium oxide (HfO2) has emerged as the most promising high-k dielectric for Metal-Oxide-Semiconductor (MOS) devices and has been highlighted as the most suitable dielectric materials to replace silicon oxide because of its comprehensive performance. In the present research, yttrium-doped HfO2 (YDH) thin films were fabricated using RF magnetron sputter deposition onto Si (100) and quartz with a variable thickness. Cross-sectional scanning electron microscopy coupled with Filmetrics revealed that film thickness values range from 700 A° to 7500 A°. Electrical properties such as AC Resistivity and current-voltage (I-V) characteristics of YDH films were studied. YDH films that were relatively thin (<1500 A°) crystallized in monoclinic phase while thicker films crystallized in cubic phase. The band gap (Eg) of the films was calculated from the optical measurements. The band gap was found to be ˜5.60 eV for monoclinic while it is ˜6.05 eV for cubic phase of YDH films. Frequency dependence of the electrical resistivity (rhoac) and the total conductivity of the films were measured. Resistivity decreased (by three orders of magnitude) with increasing frequency from 100 Hz to 1 MHz, attributed due to the hopping mechanism in YDH films. Whereas, while rhoac˜1O-m at low frequencies (100 Hz), it decreased to ˜ 104 O-cm at higher frequencies (1 MHz). Aluminum (Al) metal electrodes were deposited to fabricate a thin film capacitor with YDH layer as dielectric film thereby employing Al-YDH-Si capacitor structure. The results indicate that the capacitance of the films decrease with increasing film thickness. A detailed analysis of the electrical characteristics of YDH films is presented.

  2. 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

  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. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. Structural and chemical analysis of annealed plasma-enhanced atomic layer deposition aluminum nitride films

    SciTech Connect

    Broas, Mikael Vuorinen, Vesa; Sippola, Perttu; Pyymaki Perros, Alexander; Lipsanen, Harri; Sajavaara, Timo; Paulasto-Kröckel, Mervi

    2016-07-15

    Plasma-enhanced atomic layer deposition was utilized to grow aluminum nitride (AlN) films on Si from trimethylaluminum and N{sub 2}:H{sub 2} plasma at 200 °C. Thermal treatments were then applied on the films which caused changes in their chemical composition and nanostructure. These changes were observed to manifest in the refractive indices and densities of the films. The AlN films were identified to contain light element impurities, namely, H, C, and excess N due to nonideal precursor reactions. Oxygen contamination was also identified in the films. Many of the embedded impurities became volatile in the elevated annealing temperatures. Most notably, high amounts of H were observed to desorb from the AlN films. Furthermore, dinitrogen triple bonds were identified with infrared spectroscopy in the films. The triple bonds broke after annealing at 1000 °C for 1 h which likely caused enhanced hydrolysis of the films. The nanostructure of the films was identified to be amorphous in the as-deposited state and to become nanocrystalline after 1 h of annealing at 1000 °C.

  10. The Accuracy of an Aluminum Stepwedge Test for Machine and Film Processor Quality Assurance in Dental Radiology.

    DTIC Science & Technology

    1984-01-01

    with an aluminum stepwedge to x-rays, were almost useless in film processing control. Polanski and Smith did not define the magnitude of the pro...cessing errors they intended to detect. The problem of latent image instability and fading, as encountered by Polanski and Smith, had been investigated...in It: Moisture vapor-resistant containers. W =4T 127 Polanski and Smith (1968) stated that non-screen film exposed to x-rays with an aluminum

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. Preparation of Phosphonic Acid Functionalized Graphene Oxide-modified Aluminum Powder with Enhanced Anticorrosive Properties

    NASA Astrophysics Data System (ADS)

    He, Lihua; Zhao, Yan; Xing, Liying; Liu, Pinggui; Wang, Zhiyong; Zhang, Youwei; Liu, Xiaofang

    2017-07-01

    To improve the anticorrosive performance of aluminum powder, a common functional filler in polymer coatings, we report a novel method to prepare graphene oxide modified aluminum powder (GO-Al) using 3-aminoproplyphosphoic acid as ;link; agent. The GO nanosheets were firstly functionalized with 3-aminoproplyphosphoic acid (APSA) by the reaction of amine groups of APSA and the epoxy groups of GO. Subsequently, a layer of GO nanosheets uniformly and tightly covered the surface of flaky aluminum particle though the strong linking strength between -PO(OH)2 functional groups of the modified GO and aluminum. The hydrogen evolution experiment suggests that the GO attached on the aluminum powder could effectively improve the anticorrosive performance of the pigments.

  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. 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.

  20. 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.

  1. Variation of the intrinsic stress gradient in thin aluminum nitride films

    NASA Astrophysics Data System (ADS)

    Mehner, H.; Leopold, S.; Hoffmann, M.

    2013-09-01

    The intrinsic stress gradient variation of thin aluminum nitride (AlN) films is the central objective in this paper. For the first time, significant influence parameters on the stress gradient are identified and varied during the deposition process. The process power induced in the plasma and the gas flow ratio of the sputter gases argon and nitrogen are the two major parameters for controlling the stress gradient of deposited AlN films. The controlled avoidance as well as the controlled generation of positive and negative gradients is shown. The stress gradient was investigated by analysis of released one-side clamped cantilever test structures.

  2. 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.

  3. 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}.

  4. 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.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  7. Selected deposition of high-quality aluminum film by liquid process.

    PubMed

    Shen, Zhongrong; Matsuki, Yasuo; Shimoda, Tatsuya

    2012-05-16

    For generation of a fine aluminum pattern by conventional vacuum processing, it is necessary not only to use complex and costly instruments but also to perform an additional etching process, which may result in physical and chemical damage to the target film surface. Herein we report a simple solution process for the selected deposition of an Al pattern. Al is obtained from the decomposition of alane under dehydrogenation catalysis of a Pt nanocrystalline pattern on a substrate at ∼105-120 °C, while the self-decomposition of alane in solution is avoided in the presence of high-boiling-point amine. This deposited film generates Al crystals with a diameter of several hundred nanometers, following an epitaxial growth to a continual film. The obtained film shows high conductivity, with a resistivity close to that of bulk Al.

  8. 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.

  9. 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.

  10. 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.

  11. Influence of aluminum oxide film on thermocompression bonding of gold wire to evaporated aluminum film

    NASA Technical Reports Server (NTRS)

    Iwata, S.; Ishizaka, A.; Yamamoto, H.

    1984-01-01

    The influence of Al surface condition on the thermocompression bonding of Au wires to Al electrodes for integrated electric circuits was studied. Au wires were connected to Al electrodes by nail-head bonding after various Al surface treatments. Bonding was evaluated by measuring the wire pull strength and fraction of the number of failures at Au-Al bonds to the total number of failures. Dependence of the fraction on applied load was derived theoretically with a parameter named critical load to take into consideration the differences in Al surface condition. The relation also held explicately for various surface treatments. Characterization of the Al surface was carried out by electron microscopy for chemical analysis.

  12. Viscosity, density, and thermal conductivity of aluminum oxide and zinc oxide nanolubricants.

    PubMed

    Kedzierski, M A; Brignoli, R; Quine, K T; Brown, J S

    2017-02-01

    This paper presents liquid kinematic viscosity, density, and thermal conductivity measurements of eleven different synthetic polyolester-based nanoparticle nanolubricants (dispersions) at atmospheric pressure over the temperature range 288 K to 318 K. Aluminum oxide (Al2O3) and zinc oxide (ZnO) nanoparticles with nominal diameters of 127 nm and 135 nm, respectively, were investigated. A good dispersion of the spherical and non-spherical nanoparticles in the lubricant was maintained with a surfactant. Viscosity, density, and thermal conductivity measurements were made for the neat lubricant along with eleven nanolubricants with differing nanoparticle and surfactant mass fractions. Existing models were used to predict kinematic viscosity (±20%), thermal conductivity (±1%), and specific volume (±6%) of the nanolubricant as a function of temperature, nanoparticle mass fraction, surfactant mass fraction, and nanoparticle diameter. The liquid viscosity, density and thermal conductivity were shown to increase with respect to increasing nanoparticle mass fraction.

  13. The selective preparation of an aluminum oxide and its isomeric C-H-activated hydroxide.

    PubMed

    Zhu, Hongping; Chai, Jianfang; Jancik, Vojtech; Roesky, Herbert W; Merrill, William A; Power, Philip P

    2005-07-27

    An aluminum oxide [LAlO]2 (1) has been prepared by the oxidative addition of aluminum(I) monomer LAl (L = HC[(CMe)(NAr)]2, Ar = 2,6-iPr2C6H3) with molecular oxygen. The short Al-O bonds in Al2(mu-O)2 result in short Al...Al contacts and subsequent steric crowding of the Ar substituents from the two oriented L. 1 hydrolyzes to form [LAl(OH)]2(mu-O) (2). A C-H-activated aluminum hydroxide 4, an isomer of 1, however, is obtained by hydrolysis of the bulky aluminum amide 3 rather than by a conversion by high temperature treatment of 1. This indicates selective preparation of isomers 1 and 4.

  14. 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.

  15. Double Oxide Film Defects in Al Castings and the Effect of Different Element Additions

    NASA Astrophysics Data System (ADS)

    Chen, Q.; Caden, A. J.; Griffiths, W. D.

    Double oxide film defects consist of doubled-over oxide films containing a gas-filled crevice, and are reported to cause both reductions in mechanical properties and increases in the scatter of properties in Al alloy castings. However, the gas entrapped in a double oxide film defect during its formation may be consumed by reaction with the surrounding melt. The defect might then be closed and its harmful effects might be reduced. In the experiments reported here, an air bubble was trapped inside an Al melt for up to 1 hour. The change in the volume of the bubble was determined and the oxide film created was investigated using SEM/EDX. The experiment was conducted with additions of Ti, Zr, Mo, Hf, Sc to commercial pure aluminum and 2L99 Al alloy, and it was found that the Mo addition affected the formation of the oxide layer and might therefore accelerate the consumption of the entrapped gas. Tensile testing of sand-cast 2L99 alloy with an addition of Mo suggested that with the Mo addition the Weibull modulus for Ultimate Tensile Strength was increased. Investigation of the fracture surfaces of the test bars suggested mechanisms of how this addition may affect double oxide film defects.

  16. Aluminum-induced oxidative events in cell lines: glioma are more responsive than neuroblastoma.

    PubMed

    Campbell, A; Prasad, K N; Bondy, S C

    1999-05-01

    Aluminum, a trivalent cation unable to undergo redox reactions, has been linked to many diseases such as dialysis dementia and microcytic anemia without iron deficiency. It has also been implicated in Alzheimer's disease although this is controversial. Because cell death due to oxidative injury is suspected to be a contributory factor in many neurological diseases and aluminum neurotoxicity, glioma (C-6) and neuroblastoma (NBP2) cells were utilized to assess early changes in oxidative parameters consequent to a 48-h exposure to aluminum sulfate. A 500-microM concentration of this salt produced a significant increase in reactive oxygen species (ROS) production and a significant decrease in glutathione (GSH) content in glioma cells. However, the same concentration of the aluminum salt did not lead to any significant changes in the neuroblastoma cells. Mitochondrial respiratory activity in glioma cells was also found to be significantly higher in the aluminum treated cells. As judged by morin-metal complex formation, aluminum can enter glioma cells much more readily than neuroblastoma cells. Thus, it is possible that the cerebral target following an acute exposure to aluminum may be glial rather than neuronal.

  17. Optimization of synthesis parameters of mesoporous silica sol-gel thin films for application on 2024 aluminum alloy substrates

    NASA Astrophysics Data System (ADS)

    Recloux, Isaline; Debliquy, Marc; Baroni, Alexandra; Paint, Yoann; Lanzutti, Alex; Fedrizzi, Lorenzo; Olivier, Marie-Georges

    2013-07-01

    Silica mesoporous films were synthesized via Evaporation Induced Self-Assembly (EISA) using Pluronic P123 as templating agent and were applied on 2024 aluminum alloy for surface treatment applications. The removal of the P123 from the film required to convert the mesostructured film into a mesoporous film was particularly studied and optimized in order to be compatible with the use of an aluminum substrate. In this work, two different kinds of removal treatments were compared: calcination at high temperatures and UV/ozone treatment. Indeed, a minimum temperature of 275 °C has to be reached to completely remove the templating agent from the film. However, this treatment also leads to a decrease in mechanical properties of the aluminum substrate. In opposition, the removal by UV/ozone illumination allows getting mesoporous films at room temperature with important pore volume and high specific surface area without impacting mechanical properties of the aluminum. The effect of these treatments on mechanical properties of bare aluminum was followed by microhardness. The development of the porosity inside the film due to the elimination of the P123 was measured by combining analytical techniques (Fourier transform infrared spectroscopy FTIR, radio-frequency glow discharge optical emission spectroscopy RF-GDOES), electrochemical impedance spectroscopy (EIS) and adsorption porosimetry using a quartz crystal microbalance.

  18. Fretting Wear-Resistant, Micro-Arc Oxidation Coatings for Aluminum and Titanium Alloy Bearings (Preprint)

    DTIC Science & Technology

    2007-03-01

    AFRL-ML-WP-TP-2007-443 FRETTING WEAR-RESISTANT, MICRO-ARC OXIDATION COATINGS FOR ALUMINUM AND TITANIUM ALLOY BEARINGS (PREPRINT) K.J. Choppy...COATINGS FOR ALUMINUM AND TITANIUM ALLOY BEARINGS (PREPRINT) 5c. PROGRAM ELEMENT NUMBER 65502F 5d. PROJECT NUMBER 3005 5e. TASK NUMBER ML...PERFORMING ORGANIZATION Infoscitex Corporation 303 Bear Hill Road Waltham, MA 02451 REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S

  19. Combined optical gain and degradation measurements in DCM2 doped Tris-(8-hydroxyquinoline)aluminum thin-films

    NASA Astrophysics Data System (ADS)

    Čehovski, Marko; Döring, Sebastian; Rabe, Torsten; Caspary, Reinhard; Kowalsky, Wolfgang

    2016-04-01

    Organic laser sources offer the opportunity to integrate flexible and widely tunable lasers in polymer waveguide circuits, e.g. for Lab-on-Foil applications. Therefore, it is necessary to understand gain and degradation processes for long-term operation. In this paper we address the challenge of life-time (degradation) measurements of photoluminescence (PL) and optical gain in thin-film lasers. The well known guest-host system of aluminum-chelate Alq3 (Tris-(8-hydroxyquinoline)aluminum) as host material and the laser dye DCM2 (4-(Dicyanomethylene)-2- methyl-6-julolidyl-9-enyl-4H-pyran) as guest material is employed as laser active material. Sample layers have been built up by co-evaporation in an ultrahigh (UHV) vacuum chamber. 200nm thick films of Alq3:DCM2 with different doping concentrations have been processed onto glass and thermally oxidized silicon substrates. The gain measurements have been performed by the variable stripe length (VSL) method. This measurement technique allows to determine the thin-film waveguide gain and loss, respectively. For the measurements the samples were excited with UV irradiation (ƛ = 355nm) under nitrogen atmosphere by a passively Q-switched laser source. PL degradation measurements with regard to the optical gain have been done at laser threshold (approximately 3 μJ/cm2), five times above laser threshold and 10 times above laser threshold. A t50-PL lifetime of > 107 pulses could be measured at a maximum excitation energy density of 32 μJ/cm2. This allows for a detailed analysis of the gain degradation mechanism and therefore of the stimulated cross section. Depending on the DCM2 doping concentration C the stimulated cross section was reduced by 35 %. Nevertheless, the results emphasizes the necessity of the investigation of degradation processes in organic laser sources for long-term applications.

  20. Violent oxidation of lithium-containing aluminum alloys in liquid oxygen

    NASA Astrophysics Data System (ADS)

    Dalins, Ilmars; Karimi, Majid; Ila, Daryush

    1991-06-01

    A strong exothermic and quite well known thermite reaction involving aluminum, oxygen and transition metals (Fe, Cr, Ni, etc.) has apparently been initiated during impact testing of Alcoa aluminum alloy #2090 in liquid oxygen at NASA-MSFC. In some instances, this reaction, essentially an oxidation process, has been so intense that the Inconel 718 cup containing the aluminum alloy disk and associated impacter has melted raising certain safety concerns in the use of this alloy. Reaction products as well as the test specimen surfaces have been studied with surface science techniques like XPS/ESCA, SIMS and AES. Typically, in order to initiate the thermite reaction a temperature of approximately 1000°C is necessary. The mechanism responsible for this oxidation is of great interest. The analysis of the reaction products together with a theoretical analysis, including digital modeling has been pursued. There is strong evidence that the large relaxation energy of the aluminum oxide coating, formed during the aluminum alloy cleaning process, is causing a highly localized energy release during fracture or lattice deformation which is enhancing the oxidation process to a runaway condition. The presence of alkali atoms (Li) enhances the likelihood and intensity of the oxidation reaction. The details of the surface studies will be discussed.

  1. 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.

  2. Novel chitosan-magnesium aluminum silicate nanocomposite film coatings for modified-release tablets.

    PubMed

    Khunawattanakul, Wanwisa; Puttipipatkhachorn, Satit; Rades, Thomas; Pongjanyakul, Thaned

    2011-04-04

    Chitosan (CS), a positively charged polysaccharide, and magnesium aluminum silicate (MAS), a negatively charged clay with silicate layers, can electrostatically interact to form nanocomposite films. In this study, CS-MAS nanocomposite films were evaluated for use in tablet film coating. Effects of CS-MAS ratio and coating level on water uptake and drug release from the coated tablets were investigated. Surface and film matrix morphology of the coated film and the effect of enzymes in the simulated gastro-intestinal fluid on drug release were also examined. The results demonstrated that the CS-MAS coated tablets had a rough surface and a layered matrix film, whereas a smooth surface and dense matrix film on the CS coated tablets was found. However, the CS-MAS coated tablets provided fewer film defects than the CS coated tablets. Nanocomposite formation between CS and MAS could retard swelling and erosion of CS in the composite films in acidic medium. The higher MAS ratio of the CS-MAS coated tablets gave lower water uptake and slower drug release when compared with the CS coated tablets. Moreover, the CS-MAS films on the tablets presented good stability towards enzymatic degradation in simulated intestinal fluid. The release of drug from the CS-MAS coated tablets could be modulated by varying CS-MAS ratios and coating levels. Additionally, drug solubility also influenced drug release characteristics of the CS-MAS coated tablets. These findings suggest that the CS-MAS nanocomposites displays a strong potential for use in tablet film coating intended for modifying drug release from tablets. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Structural and optical characterizations of porous anodic alumina-aluminum nanocomposite films on borofloat substrates

    NASA Astrophysics Data System (ADS)

    Arslan, Hande Cavus; Yusufoglu, Ibrahim; Aslan, Mustafa M.

    2014-07-01

    Structural and optical properties of the porous anodic alumina (PAA)-aluminum (Al) nanocomposite and the PAA-nanostructured films on borofloat substrates are studied. The films are fabricated by the anodization of 170- to 200- and 295- to 330-nm-thick Al sputtered onto the borofloat. The anodization process is stopped at different times in order to form the PAA-Al nanocomposite films with different layer thicknesses. Then, the pore widening is applied to 189- to 210- and 430- to 495-nm-thick PAA films in 5- and 10-min intervals, respectively. The structural properties of the films are characterized by a scanning electron microscopy. The nanocomposite films are also characterized optically by total reflection and directional transmission measurements in the wavelength range between 250 and 800 nm. Our results indicate that controlling the thicknesses of both Al and the PAA layers by anodization time and the morphology of the nanostructures by chemical etching duration in the PAA layer provides unique PAA-Al nanocomposite films with desired optical properties.

  4. Ferromagnetism of zinc oxide nanograined films

    NASA Astrophysics Data System (ADS)

    Straumal, B. B.; Protasova, S. G.; Mazilkin, A. A.; Schütz, G.; Goering, E.; Baretzky, B.; Straumal, P. B.

    2013-05-01

    The reasons for the appearance of ferromagnetic properties of zinc oxide have been reviewed. It has been shown that ferromagnetism appears only in polycrystals at a quite high density of grain boundaries. The critical size of grains is about 20 nm for pure ZnO and more than 40 μm for iron-doped zinc oxide. The solubility of manganese and cobalt in zinc oxide increases significantly with a decrease in the size of grains. The dependences of the saturation magnetization on the concentrations of cobalt, manganese, and ion are nonmonotonic. Even if the size of grains is below the critical value, the ferromagnetic properties of zinc oxide depend significantly on the texture of films and the structure of amorphous intercrystallite layers.

  5. 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.

  6. Ion irradiation of the native oxide/silicon surface increases the thermal boundary conductance across aluminum/silicon interfaces

    NASA Astrophysics Data System (ADS)

    Gorham, Caroline S.; Hattar, Khalid; Cheaito, Ramez; Duda, John C.; Gaskins, John T.; Beechem, Thomas E.; Ihlefeld, Jon F.; Biedermann, Laura B.; Piekos, Edward S.; Medlin, Douglas L.; Hopkins, Patrick E.

    2014-07-01

    The thermal boundary conductance across solid-solid interfaces can be affected by the physical properties of the solid boundary. Atomic composition, disorder, and bonding between materials can result in large deviations in the phonon scattering mechanisms contributing to thermal boundary conductance. Theoretical and computational studies have suggested that the mixing of atoms around an interface can lead to an increase in thermal boundary conductance by creating a region with an average vibrational spectra of the two materials forming the interface. In this paper, we experimentally demonstrate that ion irradiation and subsequent modification of atoms at solid surfaces can increase the thermal boundary conductance across solid interfaces due to a change in the acoustic impedance of the surface. We measure the thermal boundary conductance between thin aluminum films and silicon substrates with native silicon dioxide layers that have been subjected to proton irradiation and post-irradiation surface cleaning procedures. The thermal boundary conductance across the Al/native oxide/Si interfacial region increases with an increase in proton dose. Supported with statistical simulations, we hypothesize that ion beam mixing of the native oxide and silicon substrate within ˜2.2nm of the silicon surface results in the observed increase in thermal boundary conductance. This ion mixing leads to the spatial gradation of the silicon native oxide into the silicon substrate, which alters the acoustic impedance and vibrational characteristics at the interface of the aluminum film and native oxide/silicon substrate. We confirm this assertion with picosecond acoustic analyses. Our results demonstrate that under specific conditions, a "more disordered and defected" interfacial region can have a lower resistance than a more "perfect" interface.

  7. Metallic oxide switches using thick film technology

    NASA Technical Reports Server (NTRS)

    Patel, D. N.; Williams, L., Jr.

    1974-01-01

    Metallic oxide thick film switches were processed on alumina substrates using thick film technology. Vanadium pentoxide in powder form was mixed with other oxides e.g., barium, strontium copper and glass frit, ground to a fine powder. Pastes and screen printable inks were made using commercial conductive vehicles and appropriate thinners. Some switching devices were processed by conventional screen printing and firing of the inks and commercial cermet conductor terminals on 96% alumina substrates while others were made by applying small beads or dots of the pastes between platinum wires. Static, and dynamic volt-ampere, and pulse tests indicate that the switching and self-oscillatory characteristics of these devices could make them useful in memory element, oscillator, and automatic control applications.

  8. Silicon oxide colloidal/polymer nanocomposite films

    SciTech Connect

    Wang Haifeng; Cao Wenwu; Zhou, Q.F.; Shung, K. Kirk; Huang, Y.H.

    2004-12-13

    The quarter-wavelength ({lambda}/4) acoustic matching layer, a vital component in medical ultrasonic transducer, can bridge the large acoustic impedance mismatch between the piezoelectric material and the human body. Composite materials are widely used as matching materials in order to cover the wide acoustic impedance range that cannot be accomplished by using a single-phase material. At high frequencies (>50 MHz), the {lambda}/4 matching layers become extremely thin so that the fabrication of homogeneous composite material matching layers becomes very challenging. A method is reported in this letter to fabricate sol-gel silicon oxide colloidal/polymer composite film on silicon substrate, in which the particle size of silicon oxide colloidal is between 10 and 40 nm. The acoustic impedance of the nanocomposite films versus aging temperature has been measured at the desired operating frequency.

  9. Silicon oxide colloidal/polymer nanocomposite films

    NASA Astrophysics Data System (ADS)

    Wang, Haifeng; Cao, Wenwu; Zhou, Q. F.; Shung, K. Kirk; Huang, Y. H.

    2004-12-01

    The quarter-wavelength (λ/4) acoustic matching layer, a vital component in medical ultrasonic transducer, can bridge the large acoustic impedance mismatch between the piezoelectric material and the human body. Composite materials are widely used as matching materials in order to cover the wide acoustic impedance range that cannot be accomplished by using a single-phase material. At high frequencies (>50MHz), the λ /4 matching layers become extremely thin so that the fabrication of homogeneous composite material matching layers becomes very challenging. A method is reported in this letter to fabricate sol-gel silicon oxide colloidal/polymer composite film on silicon substrate, in which the particle size of silicon oxide colloidal is between 10 and 40 nm. The acoustic impedance of the nanocomposite films versus aging temperature has been measured at the desired operating frequency.

  10. On the Role of Built-in Electric Fields on the Ignition of Oxide Coated NanoAluminum: Ion Mobility versus Fickian Diffusion

    DTIC Science & Technology

    2010-01-01

    oxide coated aluminum nanoparticles . Aluminum nanoparticles with core diameters of approximately 5 and 8 nm are simulated with 1 and 2 nm thick oxide...study their effect on the ignition of nanoparticle oxidation. The oxide shells 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13. SUPPLEMENTARY...10 nm oxide coated aluminum nanoparticles . Aluminum nanoparticles with core diameters of approximately 5 and 8 nm are simulated with 1 and 2 nm thick

  11. 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. (c) 2009 Elsevier B.V. All rights reserved.

  12. 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.

  13. 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.

  14. Superhydrophobic honeycomb-like cobalt stearate thin films on aluminum with excellent anti-corrosion properties

    NASA Astrophysics Data System (ADS)

    Xiong, Jiawei; Sarkar, D. K.; Chen, X.-Grant

    2017-06-01

    Superhydrophobic cobalt stearate thin films with excellent anti-corrosion properties were successfully fabricated on aluminum substrates via electrodeposition process. The water-repellent properties were attributed to the honeycomb-like micro-nano structure as well as low surface energy of cobalt stearate. The correlation between the surface morphology, composition as well as wetting properties and the molar ratio of inorganic cobalt salt (Co(NO3)2) and organic stearic acid (SA) abbreviated as Co/SA, in the electrolyte were studied carefully. The optimum superhydrophobic surface obtained on the electrodeposited cathodic aluminum substrate, in the mixed ethanolic solution with Co/SA molar ratio of 0.2, was found to have a maximum contact angle of 161°. The polarization resistance of superhydrophobic aluminum substrates was calculated as high as 1591 kΩ cm2, which is determined to be two orders of magnitude larger than that of the as-received aluminum substrate as 27 kΩ cm2. Electrochemical impedance spectroscopy (EIS) was also employed to evaluate the corrosion resistance properties of these samples. Furthermore, electrical equivalent circuits (EEC) have been suggested in order to better understand the corrosion phenomena on these surfaces based on the corresponding EIS data.

  15. Localized heating of nickel nitride/aluminum nitride nanocomposite films for data storage

    SciTech Connect

    Maya, L.; Thundat, T.; Thompson, J.R.; Stevenson, R.J.

    1995-11-13

    Nickel--aluminum nitride films were prepared by reactive sputtering of a nickel aluminide plate in a nitrogen plasma. The initial product is a nanocomposite containing the nickel as the nitride, Ni{sub 3}N, in aluminum nitride. Heating in vacuum to 500 {degree}C causes selective decomposition of the thermally labile nickel nitride leaving the aluminum nitride unaffected. The nickel nanocomposite is of interest for potential applications as recording media, as are other finely divided dispersions of ferromagnetic metals in insulating matrices. The nickel--aluminum nitride nanocomposite shows a moderate coercive field of 35 Oe at 300 K and, in common with ultrafine particles of ferromagnetic materials, shows superparamagnetic behavior. The Ni{sub 3}N/AlN nanocomposite was subjected to localized heating with the focused beam of an argon-ion laser; this created features several microns in width that could be imaged with a magnetic force microscope, thus confirming its potential as a high density data storage medium. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  16. Water clustering on nanostructured iron oxide films.

    PubMed

    Merte, Lindsay R; Bechstein, Ralf; Peng, Guowen; Rieboldt, Felix; Farberow, Carrie A; Zeuthen, Helene; Knudsen, Jan; Lægsgaard, Erik; Wendt, Stefan; Mavrikakis, Manos; Besenbacher, Flemming

    2014-06-30

    The adhesion of water to solid surfaces is characterized by the tendency to balance competing molecule-molecule and molecule-surface interactions. Hydroxyl groups form strong hydrogen bonds to water molecules and are known to substantially influence the wetting behaviour of oxide surfaces, but it is not well-understood how these hydroxyl groups and their distribution on a surface affect the molecular-scale structure at the interface. Here we report a study of water clustering on a moiré-structured iron oxide thin film with a controlled density of hydroxyl groups. While large amorphous monolayer islands form on the bare film, the hydroxylated iron oxide film acts as a hydrophilic nanotemplate, causing the formation of a regular array of ice-like hexameric nanoclusters. The formation of this ordered phase is localized at the nanometre scale; with increasing water coverage, ordered and amorphous water are found to coexist at adjacent hydroxylated and hydroxyl-free domains of the moiré structure.

  17. Water Clustering on Nanostructured Iron Oxide Films

    SciTech Connect

    Merte, L. R.; Bechstein, Ralf; Peng, Guowen; Rieboldt, Felix; Farberow, Carrie A.; Zeuthen, Helene; Knudsen, Jan; Laegsgaard, E.; Wendt, Stefen; Mavrikakis, Manos; Besenbacher, Fleming

    2014-06-30

    The adhesion of water to solid surfaces is characterized by the tendency to balance competing molecule–molecule and molecule–surface interactions. Hydroxyl groups form strong hydrogen bonds to water molecules and are known to substantially influence the wetting behaviour of oxide surfaces, but it is not well-understood how these hydroxyl groups and their distribution on a surface affect the molecular-scale structure at the interface. Here we report a study of water clustering on a moire´-structured iron oxide thin film with a controlled density of hydroxyl groups. While large amorphous monolayer islands form on the are film, the hydroxylated iron oxide film acts as a hydrophilic nanotemplate, causing the formation of a regular array of ice-like hexameric nanoclusters. The formation of this ordered phase is localized at the nanometre scale; with increasing water coverage, ordered and amorphous water are found to coexist at adjacent hydroxylated and hydroxyl-free domains of the moire´ structure.

  18. 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.

  19. Fabrication of Si(111) crystalline thin film on graphene by aluminum-induced crystallization

    SciTech Connect

    Høiaas, I. M.; Kim, D. C. E-mail: helge.weman@ntnu.no; Weman, H. E-mail: helge.weman@ntnu.no

    2016-04-18

    We report the fabrication of a Si(111) crystalline thin film on graphene by the aluminum-induced crystallization (AIC) process. The AIC process of Si(111) on graphene is shown to be enhanced compared to that on an amorphous SiO{sub 2} substrate, resulting in a more homogeneous Si(111) thin film structure as revealed by X-ray diffraction and atomic force microscopy measurements. Raman measurements confirm that the graphene is intact throughout the process, retaining its characteristic phonon spectrum without any appearance of the D peak. A red-shift of Raman peaks, which is more pronounced for the 2D peak, is observed in graphene after the crystallization process. It is found to correlate with the red-shift of the Si Raman peak, suggesting an epitaxial relationship between graphene and the adsorbed AIC Si(111) film with both the graphene and Si under tensile strain.

  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. 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.

  2. Crater nanochannels of anodic aluminum oxide fabricated in NH4F electrolyte

    NASA Astrophysics Data System (ADS)

    Yu, Mengshi; Cui, Huimin; Zhang, Shaoyu; Zhao, Siwei; Ai, Fuping; Zhu, Xufei

    2017-08-01

    In this work, porous anodic aluminum oxide with crater nanochannels is discovered for the first time while Al is anodized in NH4F electrolyte at high voltages. The unique structure of crater nanochannels is distinctly different from that of general porous anodic aluminum oxide (AAO) and anodic TiO2 nanotubes. A central channel appears and a circle of nanopores surround the channel while there is only one kind of pore in typical AAO and anodic TiO2 nanotubes. This finding may significantly facilitate the fabrication of special structures in AAO and anodic TiO2 nanotubes.

  3. Adhesion of oxide layer to metal-doped aluminum hydride surface: Density functional calculations

    NASA Astrophysics Data System (ADS)

    Takezawa, Tomoki; Itoi, Junichi; Kannan, Takashi

    2017-07-01

    The density functional theory (DFT) calculations were carried out to evaluate the adhesion energy of the oxide layer to the metal-doped surface of hydrogen storage material, aluminum hydride (alane, AlH3). The total energy calculations using slab model revealed that the surface doping of some metals to aluminum hydride weakens the adhesion strength of the oxide layer. The influence of titanium, iron, cobalt, and zirconium doping on adhesion strength were evaluated. Except for iron doping, the adhesion strength becomes weak by the doping.

  4. Liquid Film Migration in Warm Formed Aluminum Brazing Sheet

    NASA Astrophysics Data System (ADS)

    Benoit, M. J.; Whitney, M. A.; Wells, M. A.; Jin, H.; Winkler, S.

    2017-10-01

    Warm forming has previously proven to be a promising manufacturing route to improve formability of Al brazing sheets used in automotive heat exchanger production; however, the impact of warm forming on subsequent brazing has not previously been studied. In particular, the interaction between liquid clad and solid core alloys during brazing through the process of liquid film migration (LFM) requires further understanding. Al brazing sheet comprised of an AA3003 core and AA4045 clad alloy, supplied in O and H24 tempers, was stretched between 0 and 12 pct strain, at room temperature and 523K (250 °C), to simulate warm forming. Brazeability was predicted through thermal and microstructure analysis. The rate of solid-liquid interactions was quantified using thermal analysis, while microstructure analysis was used to investigate the opposing processes of LFM and core alloy recrystallization during brazing. In general, liquid clad was consumed relatively rapidly and LFM occurred in forming conditions where the core alloy did not recrystallize during brazing. The results showed that warm forming could potentially impair brazeability of O temper sheet by extending the regime over which LFM occurs during brazing. No change in microstructure or thermal data was found for H24 sheet when the forming temperature was increased, and thus warm forming was not predicted to adversely affect the brazing performance of H24 sheet.

  5. 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

  6. 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).

  7. 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.

  8. 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.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

    Johnston, P. H.

    2009-03-01

    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.

  11. Investigation of photoelectrochemical-oxidized p-GaSb films

    SciTech Connect

    Lee, Hsin-Ying; Huang, Hung-Lin; Lee, Ching-Ting; Petrovich Pchelyakov, Oleg; Andreevich Pakhanov, Nikolay

    2012-12-17

    GaSb oxide films were directly formed on the p-GaSb films using the bias-assisted photoelectrochemical (PEC) oxidation method. X-ray photoelectron spectroscopy analysis indicated that the resulting GaSb oxide films consisted of Ga{sub 2}O{sub 3}, Sb{sub 2}O{sub 3}, and Sb{sub 2}O{sub 5}. Different from the non-PEC oxides, the PEC derived oxide contained much more Sb{sub 2}O{sub 5} than Sb{sub 2}O{sub 3}. Besides, the interface state density between the PEC oxide and p-GaSb was lower than that of the ordinary oxide/p-GaSb interface. The high quality of the PEC-oxidized GaSb films was attributed to the increase of the stable Sb{sub 2}O{sub 5} content and decrease of the elemental Sb content in the films.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Oxidation behavior of nanostructured cobalt nickel chromium aluminum yttrium and nickel cobalt chromium aluminum yttrium sprayed by HVOF

    NASA Astrophysics Data System (ADS)

    Mercier, Dominic

    In recent years, much development has been made in the world of nanotechnologies. Hence, nanomaterials, which possess unique characteristics and excellent mechanical properties, are now being used in innovative and advanced applications. Despite the incredible potential of nanomaterials, their use is still at an embryonic stage as a result of the difficulty to mass-produce them. Among the potentially viable application remains the fabrication of nanostructured powders to produce high temperature oxidation resistance coatings. Nanostructured coatings were obtained by thermally spraying cryomilled CoNiCrAlY and NiCoCrAlY feedstock using the HVOF technique. It was found that the milling process used to prepare the powder significantly altered the microstructure of the alloy. In addition to achieving grain size refinement, significant aluminum segregation at grain boundaries was observed. Upon oxidation experiments up to 96 hours in static air at 1000°C an oxide scale composed of an adherent and dense alpha-Al2O3 inner layer with a top layer of fast growing oxides such as NiO, Cr2O3, CoAl2O4 and NiAl2O4 evolved from the coatings. It was found that the formation of a two-layer scale could be prevented through surface grinding prior to oxidation. Moreover, the comparison of the oxidation results of the powders and those of the coatings revealed that the spraying process has a considerable influence on the oxidation behavior of MCrAlYs attributable to the formation of oxide seeds during the spraying process.

  18. Enhanced electrochemical characteristics of lithium manganese oxide thin film cathodes for lithium-ion rechargeable microbatteries

    NASA Astrophysics Data System (ADS)

    Kim, Won-Seok

    Spinel LiMn2O4 (average oxidation state of Mn = 3.5) thin film has been introduced for a promising cathode of thin film lithium-ion microbatteries because of its advantages over other cathodes. Thus, many research groups have been investigating the thin film lithium manganese oxide cathode using several different techniques but only a few of them achieved acceptable electrochemical properties required for a thin film cathode for 4 V region. However, for 3 V application the wide applications of LiMn2O 4 film as a cathode in rechargeable microbatteries have been restricted by electrochemically unfavorable facts such as capacity fade on cycling and poor rate capability at high rates. In this study, we examined the mechanisms responsible for capacity fade on cycling and rate capability of LiMn 2O4 thin film cathodes with the help of pulsed laser deposition (PLD) technique. In an attempt to address these issues, a three-part experimental procedure has been designed to look at the effect of structure and compositions of the thin film cathodes on their electrochemical characteristics. First, the effect of growth temperature of the thin film cathodes has been investigated. Next, LiMn2O4 thin film cathodes doped with aluminum, which replaces Mn3+ in the spinet structure, have been synthesized and characterized as a function of the amount of aluminum substituted. Finally, ultraviolet radiation was added to a PLD system for in situ ultraviolet-assisted PLD (UVPLD) growth of cathode films. Through the addition of ultraviolet radiation, highly reactive oxygen species are generated which alter the oxygenation conditions and dynamically alter the films properties such as crystallinity and composition. A variety of characterization techniques indicate that LiMn2O 4 thin film cathodes grown at 400˜500°C exhibit the optimized electrochemical characteristics in terms of capacity, capacity retention, and rate capability. Al-doped LiMn2O4 thin films show a more stable structure

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  7. 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.

  8. 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.

  9. 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.

  10. 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

    2017-04-03

    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.

  11. 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.

  12. 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.

  13. Silicon colors: spectral selective perfect light absorption in single layer silicon films on aluminum surface and its thermal tunability.

    PubMed

    Mirshafieyan, Seyed Sadreddin; Guo, Junpeng

    2014-12-15

    Using two most abundant materials in nature: silicon and aluminum, spectral selective perfect light absorption in single layer silicon films on aluminum surface is demonstrated. Perfect light absorption is achieved due to the critical coupling of incident optical wave to the second order resonance mode of the optical cavity made of a thin silicon film on aluminum surface. Spectral selective perfect light absorption results in different optical colors corresponding to different thicknesses of silicon films. The device colors do not change when viewing from large angles with respect to the surface normal. Perfect absorption wavelength can be tuned over a wide wavelength range over 70 nm by thermal annealing. This new technology, which is low cost and compatible with silicon technology platform, paves the way for many applications such as optical color filters and wavelength selective photodetectors.

  14. 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.

  15. Complex oxide thin films for microelectronics

    NASA Astrophysics Data System (ADS)

    Suvorova, Natalya

    The rapid scaling of the device dimensions, namely in metal oxide semiconductor field effect transistor (MOSFET), is reaching its fundamental limit which includes the increase in allowable leakage current due to direct tunneling with decrease of physical thickness of SiO2 gate dielectric. The significantly higher relative dielectric constant (in the range 9--25) of the gate dielectric beyond the 3.9 value of silicon dioxide will allow increasing the physical thickness. Among the choices for the high dielectric constant (K) materials for future generation MOSFET application, barium strontium titanate (BST) and strontium titanate (STO) possess one of the highest attainable K values making them the promising candidates for alternative gate oxide. However, the gate stack engineering does not imply the simple replacement of the SiO2 with the new dielectric. Several requirements should be met for successful integration of a new material. The major one is a production of high level of interface states (Dit) compared to that of SiO 2 on Si. An insertion of a thin SiO2 layer prior the growth of high-K thin film is a simple solution that helps to limit reaction with Si substrate and attains a high quality interface. However, the combination of two thin films reduces the overall K of the dielectric stack. An optimization of the SiO2 underlayer in order to maintain the interface quality yet minimize the effect on K is the focus of this work. The results from our study are presented with emphasis on the key process parameters that improve the dielectric film stack. For in-situ growth characterization of BST and STO films sputter deposited on thermally oxidized Si substrates spectroscopic ellipsometry in combination with time of flight ion scattering and recoil spectrometry have been employed. Studies of material properties have been complemented with analytical electron microscopy. To evaluate the interface quality the electrical characterization has been employed using

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. Scanning probe studies of water nucleation on aluminum oxide and gold surfaces

    NASA Astrophysics Data System (ADS)

    Missert, N.; Copeland, R. G.

    2008-01-01

    The nucleation of nanoscale water at surfaces in humid environments is sensitive to several factors, including the details of the surface morphology, ability of the surface to hydrate and the presence of contaminants. Tapping mode atomic force microscopy was used to investigate the nucleation process as a function of relative humidity (RH) on passive aluminum and gold thin films. Films exposed to the ambient environment prior to RH exposure showed discrete structures with lateral sizes ranging from 10 to 100 nm only at RH > 70%. These structures formed preferentially at grain boundaries, triple points and regions with significant topography such as protruding grains. The morphology of the passive aluminum surface is permanently altered at the sites where discrete structures were observed; nodules with heights ranging from 0.5 to 2 nm persist even after reducing the RH to <2%. The gold surface does not show such a permanent change in morphology after reducing the RH. Passive aluminum films exposed to high RH immediately after growth (e.g. no ambient exposure) do not show discrete structures even at the highest RH exposures of 90%, suggesting a hydrophilic surface and the importance of surface hydrocarbon contaminants in affecting the distribution of the water layer.

  6. 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.

  7. 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

  8. 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.

  9. Preparations, Properties, and Applications of Periodic Nano Arrays using Anodized Aluminum Oxide and Di-block Copolymer

    NASA Astrophysics Data System (ADS)

    Noh, Kunbae

    2011-12-01

    Self-ordered arrangements observed in various materials systems such as anodic aluminum oxide, polystyrene nanoparticles, and block copolymer are of great interest in terms of providing new opportunities in nanofabrication field where lithographic techniques are broadly used in general. Investigations on self-assembled nano arrays to understand how to obtain periodic nano arrays in an efficient yet inexpensive way, and how to realize advanced material and device systems thereof, can lead to significant impacts on science and technology for many forefront device applications. In this thesis, various aspects of periodic nano-arrays have been discussed including novel preparations, properties and applications of anodized aluminum oxide (AAO) and PS-b-P4VP (S4VP) di-block copolymer self-assembly. First, long-range ordered AAO arrays have been demonstrated. Nanoimprint lithography (NIL) process allowed a faithful pattern transfer of the imprint mold pattern onto Al thin film, and interesting self-healing and pattern tripling phenomena were observed, which could be applicable towards fabrication of the NIL master mold having highly dense pattern over large area, useful for fabrication of a large-area substrate for predictable positioning of arrayed devices. Second, S4VP diblock copolymer self-assembly and S4VP directed AAO self-assembly have been demonstrated in the Al thin film on Si substrate. Such a novel combination of two dissimilar self-assembly techniques demonstrated a potential as a versatile tool for nanopatterning formation on a Si substrate, capable of being integrated into Si process technology. As exemplary applications, vertically aligned Ni nanowires have been synthesized into an S4VP-guided AAO membrane on a Si substrate in addition to anti-dot structured [Co/Pd]n magnetic multilayer using S4VP self assembly. Third, a highly hexagonally ordered, vertically parallel aluminum oxide nanotube array was successfully fabricated via hard anodization technique

  10. 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.

  11. Thermal Stability of Copper-Aluminum Alloy Thin Films for Barrierless Copper Metallization on Silicon Substrate

    NASA Astrophysics Data System (ADS)

    Wang, C. P.; Dai, T.; Lu, Y.; Shi, Z.; Ruan, J. J.; Guo, Y. H.; Liu, X. J.

    2017-08-01

    Copper thin films with thickness of about 500 nm doped with different aluminum concentrations have been prepared by magnetron sputtering on Si substrate and their crystal structure, microstructure, and electrical resistivity after annealing at various temperatures (200°C to 600°C) for 1 h or at 400°C for different durations (1 h to 11 h) investigated by grazing-incidence x-ray diffraction (GIXRD) analysis, scanning electron microscopy (SEM), and four-point probe (FPP) measurements. Cu-1.8Al alloy thin film exhibited good thermal stability and low electrical resistivity (˜5.0 μΩ cm) after annealing at 500°C for 1 h or 400°C for 7 h. No copper silicide was observed at the Cu-Al/Si interface by GIXRD analysis or SEM for this sample. This result indicates that doping Cu thin film with small amounts of Al can achieve high thermal stability and low electrical resistivity, suggesting that Cu-1.8Al alloy thin film could be used for barrierless Cu metallization on Si substrate.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Doping in zinc oxide thin films

    NASA Astrophysics Data System (ADS)

    Yang, Zheng

    Doping in zinc oxide (ZnO) thin films is discussed in this dissertation. The optimizations of undoped ZnO thin film growth using molecular-beam epitaxy (MBE) are discussed. The effect of the oxygen ECR plasma power on the growth rate, structural, electrical, and optical properties of the ZnO thin films were studied. It was found that larger ECR power leads to higher growth rate, better crystallinity, lower electron carrier concentration, larger resistivity, and smaller density of non-radiative luminescence centers in the ZnO thin films. Low-temperature photoluminescence (PL) measurements were carried out in undoped and Ga-doped ZnO thin films grown by molecular-beam epitaxy. As the carrier concentration increases from 1.8 x 1018 to 1.8 x 1020 cm-3, the dominant PL line at 9 K changes from I1 (3.368--3.371 eV), to IDA (3.317--3.321 eV), and finally to I8 (3.359 eV). The dominance of I1, due to ionized-donor bound excitons, is unexpected in n-type samples, but is shown to be consistent with the temperature-dependent Hall fitting results. We also show that IDA has characteristics of a donor-acceptor-pair transition, and use a detailed, quantitative analysis to argue that it arises from GaZn donors paired with Zn-vacancy (VZn) acceptors. In this analysis, the GaZn0/+ energy is well-known from two-electron satellite transitions, and the VZn0/- energy is taken from a recent theoretical calculation. Typical behaviors of Sb-doped p-type ZnO are presented. The Sb doping mechanisms and preference in ZnO are discussed. Diluted magnetic semiconducting ZnO:Co thin films with above room-temperature TC were prepared. Transmission electron microscopy and x-ray diffraction studies indicate the ZnO:Co thin films are free of secondary phases. The magnetization of the ZnO:Co thin films shows a free electron carrier concentration dependence, which increases dramatically when the free electron carrier concentration exceeds ˜1019 cm -3, indicating a carrier-mediated mechanism for

  18. p-type conduction in sputtered indium oxide films

    SciTech Connect

    Stankiewicz, Jolanta; Alcala, Rafael; Villuendas, Francisco

    2010-05-10

    We report p-type conductivity in intrinsic indium oxide (IO) films deposited by magnetron sputtering on fused quartz substrates under oxygen-rich ambient. Highly oriented (111) films were studied by x-ray diffraction, optical absorption, and Hall effect measurements. We fabricated p-n homojunctions on these films.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Polymer-assisted aqueous deposition of metal oxide films

    DOEpatents

    Li, DeQuan [Los Alamos, NM; Jia, Quanxi [Los Alamos, NM

    2003-07-08

    An organic solvent-free process for deposition of metal oxide thin films is presented. The process includes aqueous solutions of necessary metal precursors and an aqueous solution of a water-soluble polymer. After a coating operation, the resultant coating is fired at high temperatures to yield optical quality metal oxide thin films.

  4. 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.

  5. 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.

  6. Syntheses of rare-earth metal oxide nanotubes by the sol gel method assisted with porous anodic aluminum oxide templates

    NASA Astrophysics Data System (ADS)

    Kuang, Qin; Lin, Zhi-Wei; Lian, Wei; Jiang, Zhi-Yuan; Xie, Zhao-Xiong; Huang, Rong-Bin; Zheng, Lan-Sun

    2007-04-01

    In this paper, we report a versatile synthetic method of ordered rare-earth metal (RE) oxide nanotubes. RE (RE=Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) oxide nanotubes were successfully prepared from corresponding RE nitrate solution via the sol-gel method assisted with porous anodic aluminum oxide (AAO) templates. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM, and X-ray diffraction (XRD) have been employed to characterize the morphology and composition of the as-prepared nanotubes. It is found that as-prepared RE oxides evolve into bamboo-like nanotubes and entirely hollow nanotubes. A new possible formation mechanism of RE oxide nanotubes in the AAO channels is proposed. These high-quantity RE oxide nanotubes are expected to have promising applications in many areas such as luminescent materials, catalysts, magnets, etc.

  7. 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.

  8. Hysteresis in Lanthanide Aluminum Oxides Observed by Fast Pulse CV Measurement

    PubMed Central

    Zhao, Chun; Zhao, Ce Zhou; Lu, Qifeng; Yan, Xiaoyi; Taylor, Stephen; Chalker, Paul R.

    2014-01-01

    Oxide materials with large dielectric constants (so-called high-k dielectrics) have attracted much attention due to their potential use as gate dielectrics in Metal Oxide Semiconductor Field Effect Transistors (MOSFETs). A novel characterization (pulse capacitance-voltage) method was proposed in detail. The pulse capacitance-voltage technique was employed to characterize oxide traps of high-k dielectrics based on the Metal Oxide Semiconductor (MOS) capacitor structure. The variation of flat-band voltages of the MOS structure was observed and discussed accordingly. Some interesting trapping/detrapping results related to the lanthanide aluminum oxide traps were identified for possible application in Flash memory technology. After understanding the trapping/detrapping mechanism of the high-k oxides, a solid foundation was prepared for further exploration into charge-trapping non-volatile memory in the future. PMID:28788225

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Zinc release from atomic layer deposited zinc oxide thin films and its antibacterial effect on Escherichia coli

    NASA Astrophysics Data System (ADS)

    Kääriäinen, M.-L.; Weiss, C. K.; Ritz, S.; Pütz, S.; Cameron, D. C.; Mailänder, V.; Landfester, K.

    2013-12-01

    Zinc oxide films have been grown by atomic layer deposition (ALD) at different reaction temperatures and in various thicknesses. Zinc-ion release has been examined from the ZnO films in water and in phosphate buffered saline solution (PBS). Additionally, the antibacterial effect has been studied on Escherichia coli. The thickness of the ZnO film or its crystal orientation did not affect the rate of dissolution. ALD grown aluminum oxide films were deposited on top of the ZnO films and they acted as an effective barrier against zinc dissolution. The bacteriostatic effect was not dependent on the film thickness but both 45 nm and 280 nm thick ZnO films significantly reduced bacterial attachment and growth in dark conditions by 99.7% and 99.5%, respectively. The results indicated that photoirradiation is not required for to enhance antibacterial properties of inorganic films and that the elution of zinc ions is probably responsible for the antibacterial properties of the ZnO films. The duration of the antibacterial effect of ZnO can be controlled by accurate control of the film thickness, which is a feature of ALD, and the onset of the antibacterial effect can be delayed by a time which can be adjusted by controlling the thickness of the Al2O3 blocking layer. This gives the possibility of obtaining dual antibacterial release profiles through a nanolaminate structure of these two materials.

  17. 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.

  18. 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

  19. 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.

  20. 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