WorldWideScience

Sample records for aluminum oxide templates

  1. Fabrication of YBCO nanowires with anodic aluminum oxide (AAO) template

    Energy Technology Data Exchange (ETDEWEB)

    Dadras, Sedigheh, E-mail: dadras@alzahra.ac.ir; Aawani, Elaheh

    2015-10-15

    We have fabricated YBCO nanowires by using anodic aluminum oxide (AAO) template and sol–gel method, to investigate the fundamental properties of the one-dimensional nanostructure YBCO high-temperature superconductor and enhance its applications. The field-emission scanning electron microscopy and X-ray diffraction pattern results have shown forming of Y-123 nanowires in the template. As an outcome, the YBCO nanowires, prepared by dipping AAO template into YBCO sol method, have average diameter of about 38 nm and length of 1 μm; this is an optimum nanowire sample with larger diameter and length. The resistance–temperature measurement indicates that the onset critical temperature of these samples occurs at 91 K, and the resistance of the optimum sample at onset transition is 10 times lower than the other sample.

  2. Fabrication of Nanostructured PLGA Scaffolds Using Anodic Aluminum Oxide Templates

    CERN Document Server

    Hsueh, Cheng-Chih; Hsu, Shan-Hui; Hung, Huey-Shan

    2008-01-01

    PLGA (poly(lactic-co-glycolic acid)) is one of the most used biodegradable and biocompatible materials. Nanostructured PLGA even has great application potentials in tissue engineering. In this research, a fabrication technique for nanostructured PLGA membrane was investigated and developed. In this novel fabrication approach, an anodic aluminum oxide (AAO) film was use as the template ; the PLGA solution was then cast on it ; the vacuum air-extraction process was applied to transfer the nano porous pattern from the AAO membrane to the PLGA membrane and form nanostures on it. The cell culture experiments of the bovine endothelial cells demonstrated that the nanostructured PLGA membrane can double the cell growing rate. Compared to the conventional chemical-etching process, the physical fabrication method proposed in this research not only is simpler but also does not alter the characteristics of the PLGA. The nanostructure of the PLGA membrane can be well controlled by the AAO temperate.

  3. Electrochemical fabrication of CdS/Co nanowire arrays in porous aluminum oxide templates

    CERN Document Server

    Yoon, C H

    2002-01-01

    A procedure for preparing semiconductor/metal nanowire arrays is described, based on a template method which entails electrochemical deposition into nanometer-wide parallel pores of anodic aluminum oxide films on aluminum. Aligned CdS/Co heterostructured nanowires have been prepared by ac electrodeposition in the anodic aluminum oxide templates. By varying the preparation conditions, a variety of CdS/Co nanowire arrays were fabricated, whose dimensional properties could be adjusted.

  4. Anodic Aluminum Oxide Templates for Nano wires Array Fabrication

    International Nuclear Information System (INIS)

    This paper reports on the process developed to fabricate anodic aluminium oxide (AAO) templates suitable for the fabrication of nano wire arrays. Anodization process has been used to fabricate the AAO templates with pore diameters ranging from 15 nm to 30 nm. Electrodeposition of parallel arrays of high aspect ratio nickel nano wires were demonstrated using these fabricated AAO templates. The nano wires produced were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that the orientations of the electrodeposited nickel nano wires were governed by the deposition current and electrolyte conditions. (author)

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

    Science.gov (United States)

    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...

  6. Optical Properties of Au Nanoparticles Coated on Surface of Glass or Anodic Aluminum Oxide Template

    Institute of Scientific and Technical Information of China (English)

    FENG Jinyang; WU Can; MA Xiao; ZHANG Hongquan; ZHAO Xiujian

    2012-01-01

    Au nanoparticles coated on the surface of glass (Sample A) or on anodic aluminum oxide template surface (Sample B) were prepared using titanium dioxide sol-gel doped with chloroauric acid and with a reduction process.FE-SEM,UV-Vis spectrum and Fluorescence spectrum tests show that Au nanoparticles have been distributed randomly on the surface of glass,while deposition occurs on the surface of regular hollows for anodic aluminum oxide template.A sharp absorption peak appears at the wavelength of 536 nm for sample B,while there is a red shift,with a broader peak for sample A.A distinct fluorescence emission at the wavelength of 633 nm is detected for sample A,but no noticeable fluorescence emission has been found for Sample B.The results indicate that the microstructure and optical properties of Au nanoparticles can be modulated by different substrate.

  7. Preparation and Characterization of Fe Nanowire Arrays Embedded in Porous Anodic Aluminum Oxide Templates

    Institute of Scientific and Technical Information of China (English)

    迟广俊; 姚素薇

    2004-01-01

    Fe nanowire arrays are prepared by electrodeposition in porous anodic aluminum oxide template from a composite electrolyte solution. These nanowires have an uniform diameter of approximate 25 nm and a length in excess of 2.5μm.The micrographs and crystal structures of Fe nanowlres are studied by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and X-ray diffraction(XRD). It is found that each nanowire is essentially a single crystal and has a different orientation in each array. Hysteresis loops of Fe nanowire array show that its easy magnetization direction is perpendicular to the sample plane.

  8. Synthesis of ordered Sinanowire arrays in porous anodic aluminum oxide templates

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Highly ordered polycrystalline Si nanowire arrays were synthesized in porous anodic aluminum oxide (AAO) templates by the chemical vapor deposition (CVD)method. The morphological structure, the crystal character of Si nanowire arrays and the individual nanowire were analyzed by the transmission electron microscopy (TEM),scanning electron microscopy (SEM), atom force microscopy (AFM) and the X-ray diffraction spectrum (XRD), respectively. It is shown that most fabricated silicon nanowires (SiNWs) tend to be assembled parallelly in bundles and constructed with highly orientated arrays. This method provides a simple and low cost fabricating craftwork and the diameters and lengths of SiNWs can be controlled, the large area Si nanowire arrays can be achieved easily under such a way.The curling and twisting SiNWs are fewer than those by other synthesis methods.

  9. Synthesis of carbon nanotube arrays using ethanol in porous anodic aluminum oxide template

    Institute of Scientific and Technical Information of China (English)

    YU Guojun; WANG Sen; GONG Jinlong; ZHU Dezhang; HE Suixia; LI Yulan; ZHU Zhiyuan

    2005-01-01

    Carbon nanotube (CNT) arrays confined by porous anodic aluminum oxide (AAO) template were synthesized using ethanol as reactant carbon source at low pressure. Images by scanning electron microscope (SEM) and low magnification transmission electron microscopy (TEM) show that these CNTs have highly uniform outer diameter and length, absolutely controlled by the diameter and depth of nano-channel arrays of the AAO. High resolution transmission electron microscopy (HRTEM) imaging indicates that the graphitization of the CNT walls is better than the results reported on this kind of template-based CNT arrays, although it is not so good as that of multiwalled carbon nanotubes (MWCNTs) synthesized by catalysis. CNTs synthesized using acetylene as reactant gas show much less graphitization than those prepared using ethanol by comparing the results of HRTEM and Raman spectroscopy. The etching effects of decomposed OH radicals on the amorphous carbon and the roughness of AAO nano-channel arrays on the CNTs growth were employed to explain the graphitization and growth of the CNTs.

  10. Wetting characteristics of the anodic aluminum oxide template and fabrication of cracks using ultraviolet curable resin solution

    Science.gov (United States)

    Sung Yoon, Jae; Phuong, NguyenThi; Hwan Kim, Jeong; Choi, Doo-Sun; Whang, Kyung-hyun; Yoo, Yeong-eun

    2014-03-01

    We have investigated the wetting characteristics of the anodic aluminum oxide (AAO) template with ultraviolet curable polymer resin. The wettability of the template depends on the pore size on the surface, where it is improved with smaller pores and vice versa. Plasma treatment on the surface of the template is used to improve the wettability and the adhesion of the cured polymer to the template. And we also introduce the cracks on the polymer layer for possible application as nano-sized cavities. The resin within the pore is cleaved during the curing process so that cavities or cracks could be made which are much smaller than the original pores of the AAO template.

  11. Electrically conducting polymer nanostructures confined in anodized aluminum oxide templates (AAO

    Directory of Open Access Journals (Sweden)

    I. Blaszczyk-Lezak

    2016-03-01

    Full Text Available Intrinsically or extrinsically conducting polymers are considered good candidates for replacement of metals in specific applications. In order to further expand their applications, it seems necessary to examine the influence of confinement effects on the electric properties of nanostructured conducting polymers in comparison to the bulk. The present study reports a novel way to fabricate and characterize high quality and controllable one-dimensional (1D polymer nanostructures with promising electrical properties, with the aid of two examples polyaniline (PANI and poly(vinylidene fluoride with multiwall carbon nanotubes (PVDF-MWCNT as representative of intrinsically and extrinsically conducting polymers, respectively. In this work, porous anodic aluminum oxide (AAO templates have been used both as a nanoreactor to synthesize 1D PANI nanostructures by polymerization of the ANI monomer and as a nanomold to prepare 1D PVDFMWCNT nanorods by melt infiltration of the precursor PVDF-MWCNT film. The obtained polymer nanostructures were morphologically and chemically characterized by SEM and Confocal Raman Spectroscopy, respectively, and the electrical properties determined by Broadband Dielectric Spectroscopy (BDS in a non-destructive way. SEM study allowed to establish the final nanostructure of PANI and PVDF-MWCNT and confirmed, in both cases, the well-aligned and uniform rodlike polymer nanostructures. Confocal Raman Microscopy has been performed to study the formation of the conducting emeraldine salt of PANI through all the length of AAO nanocavities. Finally, the electrical conductivity of both types of polymer nanostructures was easily evaluated by means of Dielectric Spectroscopy.

  12. The fabrication of Ag nanoflake arrays via self-assembly on the surface of an anodic aluminum oxide template

    International Nuclear Information System (INIS)

    Vertical-aligned Ag nanoflake arrays are fabricated on the surface of an anodic aluminum oxide (AAO) template under a hydrothermal condition for the first time. The porous surface of AAO templates and the precursor solution may play key roles in the process of fabricating Ag nanoflakes. The rim of pores can provide many active sites for nucleation and growth, and then nanoflake arrays gradually form through self-assembly of Ag on the surface of AAO membranes. The product is characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and a growth mechanism of nanoflake is deduced. This work demonstrates that it is possible to make ordered nanoarrays without dissolving templates using the hydrothermal method, and this interesting Ag nanoflake arrays may provide a wider range of nanoscale applications.

  13. Electrodeposited Ni,Fe,Co and Cu single and multilayer nanowire arrays on anodic aluminum oxide template

    Institute of Scientific and Technical Information of China (English)

    Bobomurod HAMRAKULOV; In-Soo KIM; M.G.LEE; B.H.PARK

    2009-01-01

    The Ni, Fe, Co and Cu single and multilayer nanowire arrays to make perpendicular magnetic recording media were fabricated with nanoporous anodic aluminum oxide (AAO) templates from Watt solution and additives by the DC electrodeposition. The results show that the diameters of Ni, Fe, Co and Cu single and multilayer nanowires in AAO templates are 40-80 nm and the lengths are about 30 μm with the aspect ratio of 350-750. The magnetic properties of the prepared nanowires are different under different electrodepositing conditions. The remanences (Br) of Ni/Cu/Fe multilayer nanowires are lower than those of others multilayer nanowires, and coercivity (Hc) of Ni/Cu/Fe multilayer nanowires are lower than those of others multilayer nanowires. These are compatible with the required conditions of high density magnetic media devices that should have the low coercivity to easily success magnetization and high remanence to keep magnetization after removal of magnetic field.

  14. Highly Ordered Zinc Oxide Nanotubules Synthesized within the Anodic Aluminum Oxide Template

    Institute of Scientific and Technical Information of China (English)

    WANG Zhen; LI HuLin

    2001-01-01

    @@ Zinc oxide (ZnO) is a wide-band-gap semiconductor, which has a broad range of applications, e.g., in pigment, rubber additives, gas sensors, varistors and transducers1. It has recently been demonstrated that nanophase zinc oxide can be used in photocells of the Gatzel type2, which results in improved current generation efficiency. The properties of high aspect ratios and small sizes of zinc oxide nanotubules or nanowires are expected to improve the luminescence efficiency of the electro-optical devices and the sensitivity of the chemical sensors3.

  15. Highly Ordered Zinc Oxide Nanotubules Synthesized within the Anodic Aluminum Oxide Template

    Institute of Scientific and Technical Information of China (English)

    WANG; Zhen

    2001-01-01

    Zinc oxide (ZnO) is a wide-band-gap semiconductor, which has a broad range of applications, e.g., in pigment, rubber additives, gas sensors, varistors and transducers1. It has recently been demonstrated that nanophase zinc oxide can be used in photocells of the Gatzel type2, which results in improved current generation efficiency. The properties of high aspect ratios and small sizes of zinc oxide nanotubules or nanowires are expected to improve the luminescence efficiency of the electro-optical devices and the sensitivity of the chemical sensors3.  ……

  16. Highly Transparent and Flexible Triboelectric Nanogenerators with Subwavelength-Architectured Polydimethylsiloxane by a Nanoporous Anodic Aluminum Oxide Template.

    Science.gov (United States)

    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. PMID:26301328

  17. Nanostructures Based on Porous Aluminum Oxide Templates: Fabrication, Properties and Applications

    Institute of Scientific and Technical Information of China (English)

    LI HuLin

    2001-01-01

    @@ Using the template method to fabricate nanostructures is an entirely new approach for fabricating nanostructures based on self-organization that developed since the middle 1990s, which means that nanostructures can be made directly in the openings of the template under an environment of liquid or vapor. In this case the size and shape of the nano-objects are determined by the size and shape of the openings in the nanotemplates,and may vary over a wide range depending on the template used. This flexibility also extends to the range of materials deposited in the template's openings. This approach is particularly attractive since it circumvents the lithographic limitations altogether by making use of naturally occurring nanotemplates.

  18. Nanostructures Based on Porous Aluminum Oxide Templates: Fabrication, Properties and Applications

    Institute of Scientific and Technical Information of China (English)

    LI; HuLin

    2001-01-01

    Using the template method to fabricate nanostructures is an entirely new approach for fabricating nanostructures based on self-organization that developed since the middle 1990s, which means that nanostructures can be made directly in the openings of the template under an environment of liquid or vapor. In this case the size and shape of the nano-objects are determined by the size and shape of the openings in the nanotemplates,and may vary over a wide range depending on the template used. This flexibility also extends to the range of materials deposited in the template's openings. This approach is particularly attractive since it circumvents the lithographic limitations altogether by making use of naturally occurring nanotemplates.  ……

  19. Preparation of thin hexagonal highly-ordered anodic aluminum oxide (AAO) template onto silicon substrate and growth ZnO nanorod arrays by electrodeposition

    Science.gov (United States)

    Chahrour, Khaled M.; Ahmed, Naser M.; Hashim, M. R.; Elfadill, Nezar G.; Qaeed, M. A.; Bououdina, M.

    2014-12-01

    In this study, anodic aluminum oxide (AAO) templates of Aluminum thin films onto Ti-coated silicon substrates were prepared for growth of nanostructure materials. Hexagonally highly ordered thin AAO templates were fabricated under controllable conditions by using a two-step anodization. The obtained thin AAO templates were approximately 70 nm in pore diameter and 250 nm in length with 110 nm interpore distances within an area of 3 cm2. The difference between first and second anodization was investigated in details by in situ monitoring of current-time curve. A bottom barrier layer of the AAO templates was removed during dropping the voltage in the last period of the anodization process followed by a wet etching using phosphoric acid (5 wt%) for several minutes at ambient temperature. As an application, Zn nanorod arrays embedded in anodic alumina (AAO) template were fabricated by electrodeposition. Oxygen was used to oxidize the electrodeposited Zn nanorods in the AAO template at 700 °C. The morphology, structure and photoluminescence properties of ZnO/AAO assembly were analyzed using Field-emission scanning electron microscope (FESEM), Energy dispersive X-ray spectroscopy (EDX), Atomic force microscope (AFM), X-ray diffraction (XRD) and photoluminescence (PL).

  20. Effect of geometric curvature on vitrification behavior for polymer nanotubes confined in anodic aluminum oxide templates

    Science.gov (United States)

    Chen, Jiao; Li, Linling; Zhou, Dongshan; Wang, Xiaoliang; Xue, Gi

    2015-09-01

    The glass transition behavior of polystyrene (PS) nanotubes confined in cylindrical alumina nanopores was studied as a function of pore diameter (d ) and polymer tube thickness (δ). Both the calorimetric glass transition temperature and the microstructure measured by a nonradiative energy transfer method indicated that the polymer nanotube, or concave polymer thin film, exhibited significant differences in vitrification behavior compared to the planar one. A closer interchain proximity and an increased Tg were observed for polymer nanotubes with respect to the bulk polymer. Tg for polymer nanotubes was primarily dependent on the curvature radius d of the template, while it was less dependent on the thickness δ of the PS tube wall in the range of 11-23 nm. For small nanotubes (d =55 nm ) , the Tg increased as high as 18 °C above the bulk value. This vitrified property reverted back to the bulk value when the substrate was chemically removed, which indicated the crucial importance of the interfacial effect imposed by the hard wall with a concave geometry.

  1. Influence of wet etching time cycles on morphology features of thin porous Anodic Aluminum oxide (AAO) template for nanostructure's synthesis

    Science.gov (United States)

    Chahrour, Khaled M.; Ahmed, Naser M.; Hashim, M. R.; Elfadill, Nezar G.; Al-Diabat, Ahmad M.; Bououdina, M.

    2015-12-01

    This study examines the influence of chemical wet etching time cycles on the morphological features of thin porous AAO template. Pore widening via wet-etching treatment at room temperature was found to modify the pore quality of AAO template and reduces the barrier layer on the bottom of AAO pore array in order to facilitate uniform electrodeposition of nanostructures onto AAO template. High quality AAO pore arrays with different mean pore diameters (64, 70, and 87 nm) were prepared under controllable pore-widening time cycles of 10, 30 and 45 min at room temperature, respectively. The AAO templates and the produced Cu nanorods were characterized using FESEM, EDX, XRD and AFM. The results indicate that the morphology of the aligned arrays of Cu nanorods is strongly affected by the duration of etching and the removal of AAO template. This study showed that the optimum etching duration required to maintain the aligned nanorods without any fracture is approximately 5 min. In addition, the regular hemispherical concave Al surface ensuring the self-ordering of AAO pore can be established when striping is employed for 45 min. Thus, it can be inferred that the duration of wet etching treatment (striping) of Al oxide film performed after the first-step anodization plays a vital role in the final arrangement of nanopores.

  2. Preparation of well-aligned carbon nanotubes/silicon nanowires core-sheath composite structure arrays in porous anodic aluminum oxide templates

    Institute of Scientific and Technical Information of China (English)

    李梦轲; 陆梅; 王成伟; 力虎林

    2002-01-01

    The well-aligned carbon nanotubes (CNTs) arrays with opened ends were prepared in ordered pores of anodic aluminum oxide (AAO) template by the chemical vapor deposition (CVD) method. After then, silicon nanowires (SiNWs) were deposited in the hollow cavities of CNTs. By using this method, CNTs/SiNWs core-sheath composite structure arrays were synthesized successfully. Growing structures and physical properties of the CNTs/SiNWs composite structure arrays were analyzed and researched by the scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction spectrum (XRD), respectively. The field emission (FE) behavior of the CNTs/SiNWs composite structure arrays was studied based on Fowler- Nordheim tunneling mechanism and current-voltage (I -V) curve. And the photoluminescence (PL) was also characterized. Significantly, the CNTs/SiNWs core-sheath composite structure nanowire fabricated by AAO template method is characteristic of a metal/semiconductor (M/S) behavior and can be utilized to synthesize nanoscale PN junction or Schottky diode device. This process also could be useful for the fabrication of SiNWs and other nanoscale core-sheath composite structure nanowires with chemically inert interfaces for nanoscale electronic and device applications where surface oxidation is undesirable. The diameters and lengths of nanoscale composite structure arrays can be dominated easily, and the experimental result shows that the curling and twisting structures are fewer than those prepared by other synthesized methods.

  3. Preparation of well-aligned carbon nanotubes/silicon nanowires core-sheath composite structure arrays in porous anodic aluminum oxide templates

    Institute of Scientific and Technical Information of China (English)

    李梦轲; 力虎林; 陆梅; 王成伟

    2002-01-01

    The well-aligned carbon nanotubes (CNTs) arrays with opened ends were prepared in ordered pores of anodic aluminum oxide (AAO) template by the chemical vapor deposition (CVD) method. After then, silicon nanowires (SiNWs) were deposited in the hollow cavities of CNTs. By using this method, CNTs/SiNWs core-sheath composite structure arrays were synthesized successfully. Growing structures and physical properties of the CNTs/SiNWs composite structure arrays were analyzed and researched by the scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction spectrum (XRD), respectively. The field emission (FE) behavior of the CNTs/SiNWs composite structure arrays was studied based on Fowler-Nordheim tunneling mechanism and current-voltage (/-V) curve. And the photoluminescence (PL) was also characterized. Significantly, the CNTs/SiNWs core-sheath composite structure nanowire fabricated by AAO template method is characteristic of a metal/semiconductor (M/S) behavior and can be

  4. 多孔阳极氧化铝模板组装Fe纳米线及其表征%Preparation and Characterization of Fe Nanowire Arrays Embedded in Porous Anodic Aluminum Oxide Templates

    Institute of Scientific and Technical Information of China (English)

    迟广俊; 姚素薇

    2004-01-01

    Fe nanowire arrays are prepared by electrodeposition in porous anodic aluminum oxide template from a composite electrolyte solution. These nanowires have an uniform diameter of approximate 25 nm and a length in excess of 2.5μm. The micrographs and crystal structures of Fe nanowires are studied by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and X-ray diffraction(XRD). It is found that each nanowire is essentially a single crystal and has a different orientation in each array. Hysteresis loops of Fe nanowire array show that its easy magnetization direction is perpendicular to the sample plane.

  5. Hemispherical Shell Nanostructures from Metal-Stripped Embossed Alumina on Aluminum Templates

    DEFF Research Database (Denmark)

    Nielsen, Peter; Albrektsen, Ole; Simonsen, Adam Cohen;

    2011-01-01

    aluminum/ alumina (Al/Al2O3) templates as a novel and versatile nanofabrication procedure, and we demonstrate explicitly how to exploit the technique for developing large-area hexagonally close-packed hemispherical shell nanostructures by stripping noble metal layers from embossed templates fabricated from...... anodized Al. Utilizing for this process the linear relationship between anodization voltage and the resulting interpore distance in the formed oxide, it is possible to tune the radius of curvature of the resulting hemispherical shells continuously, which in turn results in tunable optical properties...

  6. Burning characteristics of individual aluminum/aluminum oxide particles

    OpenAIRE

    Ruttenberg, Eric C.

    1996-01-01

    Approved for public release; distribution is unlimited An experimental investigation was conducted in which the burning characteristics of individual aluminum/aluminum oxide particles were measured using a windowed combustion bomb at atmospheric pressure and under gravity-fall conditions. A scanning electron microscope (SEM) was used to measure the size distribution of the initial aluminum particles and the aluminum oxide residue. Analysis of the residue indicated that the mass of aluminum...

  7. Porous Anodic Aluminum Oxide with Serrated Nanochannels

    Science.gov (United States)

    Li, Dongdong; Zhao, Liang; Lu, Jia G.

    2010-03-01

    Self-assembled nanoporous anodic aluminum oxide (AAO) membrane with straight channels has long been an important tool in synthesizing highly ordered and vertically aligned quasi-1D nanostructures for various applications. Recently shape-selective nanomaterials have been achieved using AAO as a template. It is envisioned that nanowires with multi-branches will significantly increase the active functional sites for applications as sensors, catalysts, chemical cells, etc. Here AAO membranes with serrated nanochannels have been successfully fabricated via a two-step annodization method. The serrated channels with periodic intervals are aligned at an angle of ˜25^circ along the stem channels. The formation of the serrated channels is attributed to the evolution of oxygen gas bubbles and the resulted plastic deformation in oxide membrane. In order to reveal the inside channel structure, Platinum are electrodeposited into the AAO template. The as-synthesized serrated Pt nanowires demonstrate a superior electrocatalytic activity. This is attributed to the enhanced electric field strength around serrated tips as shown in the electric field simulation by COMOSL. Moreover, hierarchical serrated/straight hybrid structures can be constructed using this simple and novel self assembly technique.

  8. Oxidation kinetics of aluminum diboride

    Science.gov (United States)

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

    2013-11-01

    The oxidation characteristics of aluminum diboride (AlB2) 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 AlB2 in the onset of oxidation and final conversion fraction, with AlB2 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 AlB2 and Al+2B in both air and oxygen. AlB2 exhibited O2-pressure-independent oxidation behavior at low conversions, while the activation energies of Al+2B were higher in O2 than in air. Differences in the composition and morphology between oxidized Al+2B and AlB2 suggested that Al2O3-B2O3 interactions slowed Al+2B oxidation by converting Al2O3 on aluminum particles into a Al4B2O9 shell, while the same Al4B2O9 developed a needle-like morphology in AlB2 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 AlB2, but both appear to be resistant to oxidation in cool, dry environments.

  9. Oxidation dynamics of aluminum nanorods

    International Nuclear Information System (INIS)

    Aluminum nanorods (Al-NRs) are promising fuels for pyrotechnics due to the high contact areas with oxidizers, but their oxidation mechanisms are largely unknown. Here, reactive molecular dynamics simulations are performed to study thermally initiated burning of oxide-coated Al-NRs with different diameters (D = 26, 36, and 46 nm) in oxygen environment. We found that thinner Al-NRs burn faster due to the larger surface-to-volume ratio. The reaction initiates with the dissolution of the alumina shell into the molten Al core to generate heat. This is followed by the incorporation of environmental oxygen atoms into the resulting Al-rich shell, thereby accelerating the heat release. These results reveal an unexpectedly active role of the alumina shell as a “nanoreactor” for oxidation

  10. Oxidation kinetics of aluminum diboride

    International Nuclear Information System (INIS)

    The oxidation characteristics of aluminum diboride (AlB2) 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 AlB2 in the onset of oxidation and final conversion fraction, with AlB2 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 AlB2 and Al+2B in both air and oxygen. AlB2 exhibited O2-pressure-independent oxidation behavior at low conversions, while the activation energies of Al+2B were higher in O2 than in air. Differences in the composition and morphology between oxidized Al+2B and AlB2 suggested that Al2O3–B2O3 interactions slowed Al+2B oxidation by converting Al2O3 on aluminum particles into a Al4B2O9 shell, while the same Al4B2O9 developed a needle-like morphology in AlB2 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 AlB2, but both appear to be resistant to oxidation in cool, dry environments. - Graphical abstract: Isothermal kinetic data for AlB2 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–temperature plots, (b) conversion as a function of time, (c) Arrhenius plots used to calculate activation energies, and (d) activation energy

  11. Surfactant-Templated Mesoporous Metal Oxide Nanowires

    OpenAIRE

    Hongmei Luo; Qianglu Lin; Stacy Baber; Mahesh Naalla

    2010-01-01

    We demonstrate two approaches to prepare mesoporous metal oxide nanowires by surfactant assembly and nanoconfinement via sol-gel or electrochemical deposition. For example, mesoporous Ta2O5 and zeolite nanowires are prepared by block copolymer Pluronic 123-templated sol-gel method, and mesoporous ZnO nanowires are prepared by electrodeposition in presence of anionic surfactant sodium dodecyl sulfate (SDS) surfactant, in porous membranes. The morphologies of porous nanowires are studied by sca...

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

    Directory of Open Access Journals (Sweden)

    Gerrard Eddy Jai Poinern

    2011-02-01

    Full Text Available 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.

  13. Surfactant-Templated Mesoporous Metal Oxide Nanowires

    Directory of Open Access Journals (Sweden)

    Hongmei Luo

    2010-01-01

    Full Text Available We demonstrate two approaches to prepare mesoporous metal oxide nanowires by surfactant assembly and nanoconfinement via sol-gel or electrochemical deposition. For example, mesoporous Ta2O5 and zeolite nanowires are prepared by block copolymer Pluronic 123-templated sol-gel method, and mesoporous ZnO nanowires are prepared by electrodeposition in presence of anionic surfactant sodium dodecyl sulfate (SDS surfactant, in porous membranes. The morphologies of porous nanowires are studied by scanning electron microscopy (SEM and transmission electron microscopy (TEM analyses.

  14. Nanosized aluminum nitride hollow spheres formed through a self-templating solid-gas interface reaction

    International Nuclear Information System (INIS)

    Nanosized aluminum nitride hollow spheres were synthesized by simply heating aluminum nanoparticles in ammonia at 1000 deg. C. The as-synthesized sphere shells are polycrystalline with cavity diameters ranging from 15 to 100 nm and shell thickness from 5 to 15 nm. The formation mechanism can be explained by the nanoscale Kirkendall effect, which results from the difference in diffusion rates between aluminum and nitrogen. The Al nanoparticles served as both reactant and templates for the hollow sphere formation. The effects of precursor particle size and temperature were also investigated in terms of product morphology. Room temperature cathode luminescence spectrum of the nanosized hollow spheres showed a broad emission band centered at 415 nm, which is originated from oxygen related luminescence centers. The hollow structure survived a 4-h heat treatment at 1200 deg. C, exhibiting excellent thermal stability. - Graphical abstract: Nanosized aluminum nitride hollow spheres were synthesized by nitridation of aluminum nanoparticles at 1000 deg. C using ammonia

  15. A novel approach to large-scale formation of through-hole porous anodic aluminum template

    Institute of Scientific and Technical Information of China (English)

    Ya Nan Zhang; Miao Chen; Zhi Lu Liu; Yan Chun Zhao

    2008-01-01

    A novel anodic oxidization equipment was designed to fabricate a large number of porous anodic alumina (PAA) templates in one time.This approach improved the efficiency of the preparation of the PAA templates remarkably in a normal lab and is expected to be used for the large-scale production in the future.

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

    Science.gov (United States)

    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.

  17. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1015 Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide is a blue-green pigment obtained by calcining...

  18. Adhesive modification of indium-tin-oxide surface for template attachment for deposition of highly ordered nanostructure arrays

    Energy Technology Data Exchange (ETDEWEB)

    Gu, W. [Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123 (China); Liao, L.S., E-mail: lsliao@suda.edu.cn [Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123 (China); Cai, S.D.; Zhou, D.Y.; Jin, Z.M.; Shi, X.B.; Lei, Y.L. [Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123 (China)

    2012-08-01

    Polyvinyl alcohol (PVA), a very cheap polymer with one hydroxyl group in each repeating unit, was spun coated on the surface of an indium-tin-oxide (ITO) substrate to improve the adhesion between the substrate and a nanoporous anodic aluminum oxide (AAO) template layer for a template-directed fabrication of nanostructures. Compared with dihydroxy-terminated polystyrene (PS-dOH) and a silane coupling agent (KH550), PVA was a superior binder because of its abundant hydroxyl groups for adhesion enhancement and its low cost for applications. As an example, a highly ordered CdSe nanorod array free standing on the ITO substrate was electrochemically deposited by using an ultrathin AAO layer as the template on the PVA modified surface. It was demonstrated that the PVA modified ITO can be reliably used for the template-directed fabrication of nanostructures.

  19. Fabrication of micro-Ni arrays by electroless and electrochemical depositions with etched porous aluminum template

    Indian Academy of Sciences (India)

    Houfang Lu; Kangping Yan; Jixin Yan; Jianzhong Wang

    2010-10-01

    Nickel micro-arrays were fabricated by electroless and electrochemical deposition in an etched porous aluminum membrane. The aluminum membrane with metal characteristic could be fabricated from high-purity aluminium by electrochemical method. The aluminum reduced Ni2+ into Ni and the formed Ni nuclei served as the catalyst for further reduction of Ni2+ in electroless solution. With the help of the membrane, nickel micro-columns of about 1–2 m diameter were obtained. The surface-deposited nickel layer served as a substrate for the nickel micro-columns, and the resulting material possessed strong mechanical strength. Electrochemical deposition was operated without preparing a conductive layer on the template due to the conductivity of the aluminum membrane. Nickel micro-tubes with an outer diameter of about 1–2 m and a wall thickness in the order of tens of nm were obtained. The nickel micro-arrays were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).

  20. Monolithic Approach to Oxide Dispersion Strengthened Aluminum Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Nassau Stern Company is investigating an approach for manufacturing oxide dispersion strengthened (ODS) aluminum in bulk rather than powder form. The approach...

  1. PREPARATION AND CHARACTERIZATION OF IRON OXIDE NANOPARTICLES ON DISACCHARIDE TEMPLATES

    Directory of Open Access Journals (Sweden)

    B ANILREDDY

    2013-09-01

    Full Text Available We report here the preparation of nanoparticles of iron oxide in the presence of polysaccharidetemplates. Interaction between iron sulfate and template has been carried out in aqueous phase,followed by the selective and controlled removal of the template to achieve narrow distribution ofparticle size. Particles of iron oxide obtained have been characterized for their stability in solventmedia, size, size distribution and crystallinity and it was found that when the negative value of thezeta potential increases, particle size decreases. A narrow particle size distribution with D100 = 275nm was obtained with chitosan and starch templates. SEM measurements further confirm the particlesize measurement. Diffuse reflectance UV–VIS spectra values show that the template is completelyremoved from the final iron oxide particles and powder XRD measurements show that the peaks ofthe diffractogram are in agreement with the theoretical data of hematite. The salient observations ofour study shows that there occurs a direct correlation between zeta potential, polydispersity index,band gap energy and particle size. The crystallite size of the particles was found to be 30–35 nm. Alarge negative zeta potential was found to be advantageous for achieving lower particle sizes, as theparticles remained discrete without agglomeration.

  2. Supported lipid bilayers as templates to design manganese oxide nanoparticles

    Indian Academy of Sciences (India)

    J Maheshkumar; B Sreedhar; B U Nair; A Dhathathreyan

    2012-09-01

    This work reports on the preparation of nanoclusters of manganese oxide using biotemplating techniques. Supported lipid bilayers (SLBs) on quartz using cationic lipid [Dioctadecyldimethylammonium bromide (DOMA)] and mixed systems with neutral phospholipids dipalmitoyl phosphatidylcholine (DPPC) and dioleoyl phosphatidylcholine (DOPC) have been used as templates to synthesize these nanoparticles in a waterbased medium at room temperature. The Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM) show manganese oxide nanostructures that are composed of crystals or small clusters in the size range of 20-50 nm in diameter. Small angle XRD showed that template removal through calcining process results in nanostructures of the manganese oxide in sizes from 30 to 50 nm. Using these organized assemblies it is possible to control the nano and mesoscopic morphologies of particles and both rod-like and spherical particles can be synthesized.

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

    Science.gov (United States)

    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. PMID:26393523

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

    Science.gov (United States)

    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.

  5. Electrodeposition of Vanadium Oxide/Manganese Oxide Hybrid Thin Films on Nanostructured Aluminum Substrates

    OpenAIRE

    Rehnlund, David; Valvo, Mario; Edström, Kristina; Nyholm, Leif

    2014-01-01

    Electrodeposition of functional coatings on aluminum electrodes in aqueous solutions often is impeded by the corrosion of aluminum. In the present work it is demonstrated that electrodeposition of vanadium, oxide films on nanostructured aluminum substrates can be achieved in acidic electrolytes employing a novel strategy in which a thin interspacing layer of manganese oxide is first electrodeposited on aluminum microrod substrates. Such deposited films, which were studied using SEM, XPS, XRD,...

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

    Science.gov (United States)

    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).

  7. Hangzhou Jinjiang Group Shanxi Fusheng Aluminum Phase I 800,000 t/a Aluminum Oxide Project Started Operation

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>On October 19,the Shanxi Province Pinglu County Phase I 800,000t/a Aluminum Oxide Project of Shanxi Fusheng Aluminum Co.,Ltd,a subordinate of Hangzhou Jinjiang Group,started operation.This is the fourth Aluminum oxide project constructed and operated by Jinjiang Group.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Iron oxide nanotubes synthesized via template-based electrodeposition

    Science.gov (United States)

    Lim, Jin-Hee; Min, Seong-Gi; Malkinski, Leszek; Wiley, John B.

    2014-04-01

    Considerable effort has been invested in the development of synthetic methods for the preparation iron oxide nanostructures for applications in nanotechnology. While a variety of structures have been reported, only a few studies have focused on iron oxide nanotubes. Here, we present details on the synthesis and characterization of iron oxide nanotubes along with a proposed mechanism for FeOOH tube formation. The FeOOH nanotubes, fabricated via a template-based electrodeposition method, are found to exhibit a unique inner-surface. Heat treatment of these tubes under oxidizing or reducing atmospheres can produce either hematite (α-Fe2O3) or magnetite (Fe3O4) structures, respectively. Hematite nanotubes are composed of small nanoparticles less than 20 nm in diameter and the magnetization curves and FC-ZFC curves show superparamagnetic properties without the Morin transition. In the case of magnetite nanotubes, which consist of slightly larger nanoparticles, magnetization curves show ferromagnetism with weak coercivity at room temperature, while FC-ZFC curves exhibit the Verwey transition at 125 K.Considerable effort has been invested in the development of synthetic methods for the preparation iron oxide nanostructures for applications in nanotechnology. While a variety of structures have been reported, only a few studies have focused on iron oxide nanotubes. Here, we present details on the synthesis and characterization of iron oxide nanotubes along with a proposed mechanism for FeOOH tube formation. The FeOOH nanotubes, fabricated via a template-based electrodeposition method, are found to exhibit a unique inner-surface. Heat treatment of these tubes under oxidizing or reducing atmospheres can produce either hematite (α-Fe2O3) or magnetite (Fe3O4) structures, respectively. Hematite nanotubes are composed of small nanoparticles less than 20 nm in diameter and the magnetization curves and FC-ZFC curves show superparamagnetic properties without the Morin transition

  10. Porous silicon carbide and aluminum oxide with unidirectional open porosity as model target materials for radioisotope beam production

    CERN Document Server

    Czapski, M; Tardivat, C; Stora, T; Bouville, F; Leloup, J; Luis, R Fernandes; Augusto, R Santos

    2013-01-01

    New silicon carbide (SiC) and aluminum oxide (Al2O3) of a tailor-made microstructure were produced using the ice-templating technique, which permits controlled pore formation conditions within the material. These prototypes will serve to verify aging of the new advanced target materials under irradiation with proton beams. Before this, the evaluation of their mechanical integrity was made based on the energy deposition spectra produced by FLORA codes. (C) 2013 Elsevier B.V. All rights reserved.

  11. Two-Dimensional Porous Micro/Nano Metal Oxides Templated by Graphene Oxide.

    Science.gov (United States)

    Cao, Hailiang; Zhou, Xufeng; Zheng, Chao; Liu, Zhaoping

    2015-06-10

    Novel two-dimensional (2D) porous metal oxides with micro-/nanoarchitecture have been successfully fabricated using graphene oxide (GO) as a typical sacrificial template. GO as a 2D template ensures that the growth and fusion of metal oxides nanoparticles is restricted in the 2D plane. A series of metal oxides (NiO, Fe2O3, Co3O4, Mn2O3, and NiFe2O4) with similar nanostructure were investigated using this simple method. Some of these special nanostructured materials, such as NiO, when being used as anode for lithium-ion batteries, can exhibit high specific capacity, good rate performance, and cycling stability. Importantly, this strategy of creating a 2D porous micro/nano architecture can be easily extended to controllably synthesize other binary/polynary metal oxides nanostructures for lithium-ion batteries or other applications.

  12. Chemical Liquid Phase Deposition of Thin Aluminum Oxide Films

    OpenAIRE

    Sun, Jie; Sun, Yingchun

    2007-01-01

    Thin aluminum oxide films were deposited by a new and simple physicochemical method called chemical liquid phase deposition (CLD) on semiconductor materials. Aluminum sulfate with crystallized water and sodium bicarbonate were used as precursors for film growth, and the control of the system pH value played an important role in this experiment. The growth rate is 12 nm/h at room temperature. Post-growth annealing not only densifies and purifies the films, but results in film crystallization a...

  13. Tris(8-hydroxyquinoline)aluminum (III) (Alq3) nanowires templated from an eggshell membrane

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Tu, E-mail: tulee@cc.ncu.edu.t [Department of Chemical and Materials Engineering, National Central University, 300 Jhong-Da Rd, Jhong-Li City 320, Taiwan (China); Chang, Shih Chia; Peng, Jen Fan [Department of Chemical and Materials Engineering, National Central University, 300 Jhong-Da Rd, Jhong-Li City 320, Taiwan (China)

    2010-07-30

    One to 2-{mu}m long, {<=} 400-nm wide amorphous tris(8-hydroxyquinoline)aluminum (III) (Alq3) nanowires (NWs) grown from the 15-min boiled outer shell membrane (OSM) of the hen's egg and from the OSM solution cast film via thermal evaporation with a source temperature of 260 {sup o}C and a substrate temperature of 138 {sup o}C under 6.7 x 10{sup -2} Pa gave about 1.4 to 1.7 times more photoluminescence emission than the control Alq3 sample did, which was grown from the plain glass surface. The characteristic bonding energies of C 1s X-ray photoelectron signal at 282 eV, O 1s signal at 529 eV and N 1s signal at 397 eV suggested that the relatively high NW density for the 15-min boiled OSM and the OSM solution cast film, was mainly caused by the formation of the O=C-O-C=O anhydride moiety and the C=N group in the proteinaceous OSM at high temperature of 90 {sup o}C to 100 {sup o}C. Therefore, we proposed that the 15-min boiled OSM and the OSM solution cast film apparently served as good templates by providing nano-regions of high concentration of the O=C-O-C=O anhydride groups and the C=N groups for nesting the Alq3 gas molecules to form nano-conical Alq3 nuclei for the growth of long and narrow NWs.

  14. Templating Routes to Supported Oxide Catalysts by Design

    Energy Technology Data Exchange (ETDEWEB)

    Notestein, Justin M [Northwestern Univ., Evanston, IL (United States); Northwestern Univ., Evanston, IL (United States). Center for Catalysis and Surface Science; Northwestern Univ., Evanston, IL (United States). Dept. of Chemical and Biological Engineering

    2016-09-08

    The rational design and understanding of supported oxide catalysts requires at least three advancements, in order of increasing complexity: the ability to quantify the number and nature of active sites in a catalytic material, the ability to place external controls on the number and structure of these active sites, and the ability to assemble these active sites so as to carry out more complex functions in tandem. As part of an individual investigator research program that is integrated with the Northwestern University Institute for Catalysis in Energy Processes (ICEP) as of 2015, significant advances were achieved in these three areas. First, phosphonic acids were utilized in the quantitative assessment of the number of active and geometrically-available sites in MOx-SiO2 catalysts, including nanocrystalline composites, co-condensed materials, and grafted structures, for M=Ti, Zr, Hf, Nb, and Ta. That work built off progress in understanding supported Fe, Cu, and Co oxide catalysts from chelating and/or multinuclear precursors to maximize surface reactivity. Secondly, significant progress was made in the new area of using thin oxide overcoats containing ‘nanocavities’ from organic templates as a method to control the dispersion and thermal stability of subsequently deposited metal nanoparticles or other catalytic domains. Similar methods were used to control surface reactivity in SiO2-Al2O3 acid catalysts and to control reactant selectivity in Al2O3-TiO2 photocatalysts. Finally, knowledge gained from the first two areas has been combined to synthesize a tandem catalyst for hydrotreating reactions and an orthogonal tandem catalyst system where two subsequent reactions in a reaction network are independently controlled by light and heat. Overall, work carried out under this project significantly advanced the knowledge of synthesis-structure-function relationships in supported oxide catalysts for energy applications.

  15. Templating Routes to Supported Oxide Catalysts by Design

    Energy Technology Data Exchange (ETDEWEB)

    Notestein, Justin M. [Northwestern Univ., Evanston, IL (United States)

    2016-09-08

    The rational design and understanding of supported oxide catalysts requires at least three advancements, in order of increasing complexity: the ability to quantify the number and nature of active sites in a catalytic material, the ability to place external controls on the number and structure of these active sites, and the ability to assemble these active sites so as to carry out more complex functions in tandem. As part of an individual investigator research program that is integrated with the Northwestern University Institute for Catalysis in Energy Processes (ICEP) as of 2015, significant advances were achieved in these three areas. First, phosphonic acids were utilized in the quantitative assessment of the number of active and geometrically-available sites in MOx-SiO2 catalysts, including nanocrystalline composites, co-condensed materials, and grafted structures, for M=Ti, Zr, Hf, Nb, and Ta. That work built off progress in understanding supported Fe, Cu, and Co oxide catalysts from chelating and/or multinuclear precursors to maximize surface reactivity. Secondly, significant progress was made in the new area of using thin oxide overcoats containing ‘nanocavities’ from organic templates as a method to control the dispersion and thermal stability of subsequently deposited metal nanoparticles or other catalytic domains. Similar methods were used to control surface reactivity in SiO2-Al2O3 acid catalysts and to control reactant selectivity in Al2O3-TiO2 photocatalysts. Finally, knowledge gained from the first two areas has been combined to synthesize a tandem catalyst for hydrotreating reactions and an orthogonal tandem catalyst system where two subsequent reactions in a reaction network are independently controlled by light and heat. Overall, work carried out under this project significantly advanced the knowledge of synthesis-structure-function relationships in supported

  16. 21 CFR 73.3110a - Chromium-cobalt-aluminum oxide.

    Science.gov (United States)

    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....

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

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Subodh K. Das; Shridas Ningileri

    2006-03-17

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

  18. Alkaline oxide conversion coatings for aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. Shuttle Redesigned Solid Rocket Motor aluminum oxide investigations

    Science.gov (United States)

    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.

  20. Thermocurrent dosimetry with high purity aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    Fullerton, G.D.; Cameron, J.R.; Moran, P.R.

    1976-01-01

    The application of thermocurrent (TC) to ionizing radiation dosimetry was studied. It was shown that TC in alumina (Al/sub 2/O/sub 3/) has properties that are suited to personnel dosimetry and environmental monitoring. TC dosimeters were made from thin disks of alumina. Aluminum electrodes were evaporated on each side: on one face a high voltage electrode and on the opposite face a measuring electrode encircled by a guard ring. Exposure to ionizing radiation resulted in stored electrons and holes in metastable trapping sites. The signal was read-out by heating the dosimeter with a voltage source and picnometer connected in series between the opposite electrodes. The thermally remobilized charge caused a transient TC. The thermogram, TC versus time or temperature, is similar to a TL glow curve. Either the peak current or the integrated current is a measure of absorbed dose. Six grades of alumina were studied from a total of four commercial suppliers. All six materials displayed radiation induced TC signals. Sapphire of uv-grade quality from the Adolf Meller Co. (AM) had the best dosimetry properties of those investigated. Sources of interference were studied. Thermal fading, residual signal and radiation damage do not limit TC dosimetry. Ultraviolet light can induce a TC response but it is readily excluded with uv-opaque cladding. Improper surface preparation prior to electrode evaporation was shown to cause interference. A spurious TC signal resulted from polarization of surface contaminants. Spurious TC was reduced by improved cleaning prior to electrode application. Polished surfaces resulted in blocking electrodes and caused a sensitivity shift due to radiation induced thermally activated polarization. This was not observed with rough cut surfaces.

  1. Thermally stimulated luminescence studies in combustion synthesized polycrystalline aluminum oxide

    Indian Academy of Sciences (India)

    K R Nagabhushana; B N Lakshminarasappa; D Revannasiddaiah; Fouran Singh

    2008-08-01

    Synthesis of materials by combustion technique results in homogeneous and fine crystalline product. Further, the technique became more popular since it not only saved time and energy but also was easy to process. Aluminum oxide phosphor was synthesized by using urea as fuel in combustion reaction. Photoluminescence (PL) and thermally stimulated luminescence (TSL) characteristics of -irradiated aluminum oxide samples were studied. A broad PL emission with a peak at ∼ 465 nm and a pair of strong and sharp emissions with peaks at 679 and 695 nm were observed in -rayed samples. The PL intensity was observed to increase with increase in -ray dose. Two prominent and well resolved TSL glows with peaks at 210°C and 365°C were observed in all -irradiated Al2O3 samples. The TSL intensity was also found to increase with increase in -ray dose. The TSL glow curves indicated second order kinetics.

  2. Oxide mediated spectral shifting in aluminum resonant optical antennas.

    Science.gov (United States)

    Schwab, Patrick M; Moosmann, Carola; Dopf, Katja; Eisler, Hans-Jürgen

    2015-10-01

    As a key feature among metals showing good plasmonic behavior, aluminum extends the spectrum of achievable plasmon resonances of optical antennas into the deep ultraviolet. Due to degradation, a native oxide layer gives rise to a metal-core/oxide-shell nanoparticle and influences the spectral resonance peak position. In this work, we examine the role of the underlying processes by applying numerical nanoantenna models that are experimentally not feasible. Finite-difference time-domain simulations are carried out for a large variety of elongated single-arm and two-arm gap nanoantennas. In a detailed analysis, which takes into account the varying surface-to-volume ratio, we show that the overall spectral shift toward longer wavelengths is mainly driven by the higher index surrounding material rather than by the decrease of the initial aluminum volume. In addition, we demonstrate experimentally that this shifting can be minimized by an all-inert fabrication and subsequent proof-of-concept encapsulation.

  3. Catalytic Behaviour of Mesoporous Cobalt-Aluminum Oxides for CO Oxidation

    Directory of Open Access Journals (Sweden)

    Ankur Bordoloi

    2014-01-01

    Full Text Available Ordered mesoporous materials are promising catalyst supports due to their uniform pore size distribution, high specific surface area and pore volume, tunable pore sizes, and long-range ordering of the pore packing. The evaporation-induced self-assembly (EISA process was applied to synthesize mesoporous mixed oxides, which consist of cobalt ions highly dispersed in an alumina matrix. The characterization of the mesoporous mixed cobalt-aluminum oxides with cobalt loadings in the range from 5 to 15 wt% and calcination temperatures of 673, 973, and 1073 K indicates that Co2+ is homogeneously distributed in the mesoporous alumina matrix. As a function of the Co loading, different phases are present comprising poorly crystalline alumina and mixed cobalt aluminum oxides of the spinel type. The mixed cobalt-aluminum oxides were applied as catalysts in CO oxidation and turned out to be highly active.

  4. Characterization of Anodic Aluminum Oxide Membrane with Variation of Crystallizing Temperature for pH Sensor.

    Science.gov (United States)

    Yeo, Jin-Ho; Lee, Sung-Gap; Jo, Ye-Won; Jung, Hye-Rin

    2015-11-01

    We fabricated electrolyte-dielectric-metal (EDM) device incorporating a high-k Al2O3 sensing membrane from a porous anodic aluminum oxide (AAO) using a two step anodizing process for pH sensors. In order to change the properties of the AAO template, the crystallizing temperature was varied from 400 degrees C to 700 degrees C over 2 hours. The structural properties were observed by field emission scanning electron microscopy (FE-SEM). The pH sensitivity increased with an increase in the crystallizing temperature from 400 degrees C to 600 degrees C. However at 700 degrees C, deformation occurred. The porous AAO sensor with a crystallizing temperature of 600 degrees C displayed the good sensitivity and long-term stability and the values were 55.7 mV/pH and 0.16 mV/h, respectively. PMID:26726567

  5. Atomic layer deposited aluminum oxide barrier coatings for packaging materials

    Energy Technology Data Exchange (ETDEWEB)

    Hirvikorpi, Terhi, E-mail: terhi.hirvikorpi@vtt.f [Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL), P.O. Box 70, FI-02151 Espoo (Finland); Vaehae-Nissi, Mika, E-mail: mika.vaha-nissi@vtt.f [Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL), P.O. Box 70, FI-02151 Espoo (Finland); Mustonen, Tuomas, E-mail: tuomas.mustonen@vtt.f [Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL), P.O. Box 70, FI-02151 Espoo (Finland); Iiskola, Eero, E-mail: eero.iiskola@kcl.f [Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL), P.O. Box 70, FI-02151 Espoo (Finland); Karppinen, Maarit, E-mail: maarit.karppinen@tkk.f [Laboratory of Inorganic Chemistry, Department of Chemistry, Helsinki University of Technology, P.O. Box 6100, FI-02015 TKK (Finland)

    2010-03-01

    Thin aluminum oxide coatings have been deposited at a low temperature of 80 {sup o}C on various uncoated papers, polymer-coated papers and boards and plain polymer films using the atomic layer deposition (ALD) technique. The work demonstrates that such ALD-grown Al{sub 2}O{sub 3} coatings efficiently enhance the gas-diffusion barrier performance of the studied porous and non-porous materials towards oxygen, water vapor and aromas.

  6. Effect of aluminum metal surface on oxidation of iodide under gamma irradiation conditions

    International Nuclear Information System (INIS)

    The effects of aluminum surface on I- oxidation under gamma irradiation were investigated. Without irradiation, only O2 oxidized I- at pH < 2, and aluminum expedited the oxidation reaction. With irradiation, the radiolysis products from water and air oxidized I- into I3-. At pH < 2, O2 generated by water radiolysis additionally oxidized I-. However, at pH > 6, the H2O2 radiolysis product reduced I3- into I-. A smaller amount of I3- was observed in pH 1.9 and 3.3 solutions in contact with aluminum under irradiation because oxidants preferentially oxidize aluminum rather than I-. Moreover, for pH < 6.0, even less I3- was formed by aluminum exposed to air because air radiolysis products also preferentially oxidized aluminum. (author)

  7. Anodic aluminum oxide with fine pore size control for selective and effective particulate matter filtering

    Science.gov (United States)

    Zhang, Su; Wang, Yang; Tan, Yingling; Zhu, Jianfeng; Liu, Kai; Zhu, Jia

    2016-07-01

    Air pollution is widely considered as one of the most pressing environmental health issues. Particularly, atmospheric particulate matters (PM), a complex mixture of solid or liquid matter suspended in the atmosphere, are a harmful form of air pollution due to its ability to penetrate deep into the lungs and blood streams, causing permanent damages such as DNA mutations and premature death. Therefore, porous materials which can effectively filter out particulate matters are highly desirable. Here, for the first time, we demonstrate that anodic aluminum oxide with fine pore size control fabricated through a scalable process can serve as effective and selective filtering materials for different types of particulate matters (such as PM2.5, PM10). Combining selective and dramatic filtering effect, fine pore size control and a scalable process, this type of anodic aluminum oxide templates can potentially serve as a novel selective filter for different kinds of particulate matters, and a promising and complementary solution to tackle this serious environmental issue.

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

    Science.gov (United States)

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

    2016-05-01

    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. Prediction of new thermodynamically stable aluminum oxides

    CERN Document Server

    Liu, Yue; Wang, Shengnan; Zhu, Qiang; Dong, Xiao; Kresse, Georg

    2015-01-01

    Recently, it has been shown that under pressure, unexpected and counterintuitive chemical compounds become stable. Laser shock experiments (A. Rode, unpublished) on alumina (Al2O3) have shown non-equilibrium decomposition of alumina with the formation of free Al and a mysterious transparent phase. Inspired by these observations, with have explored the possibility of the formation of new chemical compounds in the system Al-O. Using the variable-composition structure prediction algorithm USPEX, in addition to the well-known Al2O3, we have found two extraordinary compounds Al4O7 and AlO2 to be thermodynamically stable in the pressure range 330-443 GPa and above 332 GPa, respectively. Both of these compounds at the same time contain oxide O2- and peroxide O22- ions, and both are insulating. Peroxo-groups are responsible for gap states, which significantly reduce the electronic band gap of both Al4O7 and AlO2.

  10. Hard template synthesis of metal nanowires

    Directory of Open Access Journals (Sweden)

    Go eKawamura

    2014-11-01

    Full Text Available Metal nanowires (NWs have attracted much attention because of their high electron conductivity, optical transmittance and tunable magnetic properties. Metal NWs have been synthesized using soft templates such as surface stabilizing molecules and polymers, and hard templates such as anodic aluminum oxide, mesoporous oxide, carbon nanotubes. NWs prepared from hard templates are composites of metals and the oxide/carbon matrix. Thus, selecting appropriate elements can simplify the production of composite devices. The resulting NWs are immobilized and spatially arranged, as dictated by the ordered porous structure of the template. This avoids the NWs from aggregating, which is common for NWs prepared with soft templates in solution. Herein, the hard template synthesis of metal NWs is reviewed, and the resulting structures, properties and potential applications are discussed.

  11. Radioluminescence of rare-earth doped aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    Santiago, M.; Molina, P. [Universidad Nacional del Centro de la Provincia de Buenos Aires, Instituto de Fisica Arroyo Seco, Pinto 399, 7000 Tandil (Argentina); Barros, V. S.; Khoury, H. J.; Elihimas, D. R., E-mail: msantiag@exa.unicen.edu.ar [Universidade Federal de Pernambuco, Departamento de Energia Nuclear, Av. Prof. Luiz Freire 1000, Recife, PE 50740-540 (Brazil)

    2011-10-15

    Carbon-doped aluminum oxide (Al{sub 2}O{sub 3}:C) is one of the most used radioluminescence (Rl) materials for fiberoptic dosimetry due to its high efficiency and commercial availability. However, this compound presents the drawback of emitting in the spectral region, where the spurious radioluminescence of fibers is also important. In this work, the radioluminescence response of rare-earth doped Al{sub 2}O{sub 3} samples has been evaluated. The samples were prepared by mixing stoichiometric amounts of aluminum nitrate, urea and dopants with different amounts of terbium, samarium, cerium and thulium nitrates varying from 0 to 0.15 mo 1%. The influence of the different activators on the Rl spectra has been investigated in order to determine the feasibility of using these compounds for Rl fiberoptic dosimetry. (Author)

  12. Core–Shell Electrospun Hollow Aluminum Oxide Ceramic Fibers

    Directory of Open Access Journals (Sweden)

    Jonathan W. Rajala

    2015-10-01

    Full Text Available In this work, core–shell electrospinning was employed as a simple method for the fabrication of composite coaxial polymer fibers that became hollow ceramic tubes when calcined at high temperature. The shell polymer solution consisted of polyvinyl pyrollidone (PVP in ethanol mixed with an aluminum acetate solution to act as a ceramic precursor. The core polymer was recycled polystyrene to act as a sacrificial polymer that burned off during calcination. The resulting fibers were analyzed with X-ray diffraction (XRD and energy dispersive spectroscopy (EDS to confirm the presence of gamma-phase aluminum oxide when heated at temperatures above 700 °C. The fiber diameter decreased from 987 ± 19 nm to 382 ± 152 nm after the calcination process due to the polymer material being burned off. The wall thickness of these fibers is estimated to be 100 nm.

  13. Chemical Liquid Phase Deposition of Thin Aluminum Oxide Films

    Institute of Scientific and Technical Information of China (English)

    SUN,Jie(孙捷); SUN,Ying-Chun(孙迎春)

    2004-01-01

    Thin aluminum oxide films were deposited by a new and simple physicochemical method called chemical liquid phase deposition (CLD) on semiconductor materials. Aluminum sulfate with crystallized water and sodium bicarbonate were used as precursors for film growth, and the control of the system's pH value played an important role in this experiment. The growth rate is 12 nm/h with the deposition at [Al2(SO4)3]=0.0837 mol·L-1, [NaHCO3]=0.214 mol·L-1, 15 ℃. Post-growth annealing not only densifies and purifies the films, but results in film crystallization as well, Excellent quality of A12O3 films in this work is supported by electron dispersion spectroscopy,Fourier transform infrared spectrum, X-ray diffraction spectrum and scanning electron microscopy photograph.

  14. Irradiation behavior of uranium oxide - Aluminum dispersion fuel

    International Nuclear Information System (INIS)

    An oxide version of the DART code has been generated in order to assess the irradiation behavior of UO2-Al dispersion fuel. The aluminum-fuel interaction models were developed based on U3O8-Al irradiation data. Deformation of the fuel element occurs due to fuel particle swelling driven by both solid and gaseous fission products and as a consequence of the interaction between the fuel particles and the aluminum matrix. The calculations show that, with the assumption that the correlations derived from U3O8 are valid for UO2, the LEU UO2-Al with a 42% fuel volume loading (4 g U/cm3 ) irradiated at fuel temperatures greater than 413 K should undergo breakaway swelling at core burnups greater than about 1.12 x 1027 fissions m-3 (∼63% 235U burnup). (author)

  15. Standard specification for nuclear-grade aluminum oxide pellets

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This specification applies to pellets of aluminum oxide that may be ultimately used in a reactor core, for example, as filler or spacers within fuel, burnable poison, or control rods. In order to distinguish between the subject pellets and “burnable poison” pellets, it is established that the subject pellets are not intended to be used as neutron-absorbing material. 1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

  16. Formation of Anodic Aluminum Oxide with Branched and Meshed Pores.

    Science.gov (United States)

    Kim, Byeol; Lee, Jin Seok

    2016-06-01

    Anodic aluminum oxide (AAO), with a self-ordered hexagonal array, is important for various applications in nanofabrication including as the fabrication of nanotemplates and other nanostructures. With the consideration, there have been many efforts to control the characteristic parameters of porous anodic alumina by adjustment of the anodizing conditions such as the electrolyte, temperature, applied potential, and Al purity. In particular, impurities in Al are changing the morphology of an alumina film; however, the formation mechanism has not yet been explained. In this work, we anodized a high purity (99.999%, Al(high)) and low purity (99.8%, Al(low)) aluminum foil by a two-step anodization process in an oxalic acid solution or phosphoric acid. It was found that the purity of aluminum foil has influenced the morphology of the alumina film resulting in branched and meshed pores. Also, electrochemical analysis indicated that the branched and meshed pores in the low-purity Al foil formed by the presence of impurities. Impurities act as defects and change the general growth mechanism for pore formation by inducing an electric field imbalance during anodization. This work contributes to the research field of topographical chemistry and applied fields including nanofabrication. PMID:27427755

  17. Morphology of Platinum Nanowire Array Electrodeposited Within Anodic Aluminium Oxide Template Characterized by Atomic Force Microscopy

    Institute of Scientific and Technical Information of China (English)

    孔令斌; 陆梅; 李梦轲; 郭新勇; 力虎林

    2003-01-01

    Uniform platinum nanowires were synthesized by electrodepositing the platinum under a very low altering current frequency (20Hz) and increasing voltage (5-15 V) in the pores of anodic aluminium oxide (AAO) template.Atomic force microscopy observation indicates that the template membranes we obtained have hexagonally closepacked nanochannels. The platinum nanowires have highly ordered arrays after partially dissolving the aluminium oxide membrane. With the increasing dissolving time, the platinum nanowire array collapsed. A concave topography of the aluminium substrate was observed after the aluminium oxide membrane was dissolved completely and the platinum nanowires were released from the template. Platinum nanowires were also characterized by transmission electron microscopy and the phase structure of the Al/AAO/Pt composite was proven by x-ray diffraction.

  18. Chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade aluminum oxide and aluminum oxide-boron carbide composite pellets

    Energy Technology Data Exchange (ETDEWEB)

    1981-01-01

    Aluminum oxide pellets are used in a reactor core as filler or spacers within fuel, burnable poison, or control rods. In order to be suitable for this purpose, the material must meet certain criteria for impurity content. The test methods in the standard are designed to show whether or not a given material meets these specifications. The following analytical procedures are described in detail: boron by titrimetry; separation of boron by mass spectrometry; isotopic composition by mass spectrometry; separation of halides by pyrohydrolysis; fluoride by ion-selective electrode; chloride, bromide, and iodide by amperometric microtitrimetry; trace elements by emission spectroscopy. (JMT)

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

    Energy Technology Data Exchange (ETDEWEB)

    Vinardell, M. P., E-mail: mpvinardellmh@ub.edu; Sordé, A. [Universitat de Barcelona, Departament de Fisiologia, Facultat de Farmàcia (Spain); Díaz, J. [Universitat de Barcelona CCiT, Scientific and Technological Centers (Spain); Baccarin, T.; Mitjans, M. [Universitat de Barcelona, Departament de Fisiologia, Facultat de Farmàcia (Spain)

    2015-02-15

    Al{sub 2}O{sub 3} 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 (HC{sub 50}) 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 Al{sub 2}O{sub 3}, but not on Al{sub 2}O{sub 3}. The drop in HC{sub 50} 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.

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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. PMID:25125114

  2. Synthesis of iron oxide nanoparticles of narrow size distribution on polysaccharide templates

    Indian Academy of Sciences (India)

    M Nidhin; R Indumathy; K J Sreeram; Balachandran Unni Nair

    2008-02-01

    We report here the preparation of nanoparticles of iron oxide in the presence of polysaccharide templates. Interaction between iron (II) sulfate and template has been carried out in aqueous phase, followed by the selective and controlled removal of the template to achieve narrow distribution of particle size. Particles of iron oxide obtained have been characterized for their stability in solvent media, size, size distribution and crystallinity and found that when the negative value of the zeta potential increases, particle size decreases. A narrow particle size distribution with 100 = 275 nm was obtained with chitosan and starch templates. SEM measurements further confirm the particle size measurement. Diffuse reflectance UV–vis spectra values show that the template is completely removed from the final iron oxide particles and powder XRD measurements show that the peaks of the diffractogram are in agreement with the theoretical data of hematite. The salient observations of our study shows that there occurs a direct correlation between zeta potential, polydispersity index, bandgap energy and particle size. The crystallite size of the particles was found to be 30–35 nm. A large negative zeta potential was found to be advantageous for achieving lower particle sizes, owing to the particles remaining discrete without agglomeration.

  3. Aluminum Oxide Formation On Fecral Catalyst Support By Electro-Chemical Coating

    Directory of Open Access Journals (Sweden)

    Yang H.S.

    2015-06-01

    Full Text Available FeCrAl is comprised essentially of Fe, Cr, Al and generally considered as metallic substrates for catalyst support because of its advantage in the high-temperature corrosion resistance, high mechanical strength, and ductility. Oxidation film and its adhesion on FeCrAl surface with aluminum are important for catalyst life. Therefore various appropriate surface treatments such as thermal oxidation, Sol, PVD, CVD has studied. In this research, PEO (plasma electrolytic oxidation process was applied to form the aluminum oxide on FeCrAl surface, and the formed oxide particle according to process conditions such as electric energy and oxidation time were investigated. Microstructure and aluminum oxide particle on FeCrAl surface after PEO process was observed by FE-SEM and EDS with element mapping analysis. The study presents possibility of aluminum oxide formation by electro-chemical coating process without any pretreatment of FeCrAl.

  4. Growth of tungsten oxide on carbon nanowalls templates

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hua, E-mail: wanghua@dlou.edu.cn [Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China); College of Fisheries and Life Science, Dalian Ocean University, Dalian 116023 (China); Su, Yan [Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China); Chen, Shuo, E-mail: shuochen@dlut.edu.cn [Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China); Quan, Xie [Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China)

    2013-03-15

    Highlights: ► Tungsten oxide deposited on carbon nanowalls by hot filament chemical vapor deposition technique. ► This composite has two-dimensional uniform morphology with a crystalline structure of monoclinic tungsten trioxide. ► Surface photoelectric voltage measurements show that this product has photoresponse properties. - Abstract: In the present work we present a simple approach for coupling tungsten oxide with carbon nanowalls. The two-dimensional carbon nanowalls with open boundaries were grown using plasma enhanced hot filament chemical vapor deposition, and the subsequent tungsten oxide growth was performed in the same equipment by direct heating of a tungsten filament. The tungsten oxide coating is found to have uniform morphology with a crystalline structure of monoclinic tungsten trioxide. Surface photoelectric voltage measurements show that this product has photoresponse properties. The method of synthesis described here provides an operable route to the production of two-dimensional tungsten oxide nanocomposites.

  5. Template-assisted patterning of functional polymers

    OpenAIRE

    Haberkorn, Niko

    2010-01-01

    In this thesis, anodic aluminum oxide (AAO) membranes, which provide well-aligned uniform mesoscopic pores with adjustable pore parameters, were fabricated and successfully utilized as templates for the fabrication of functional organic nanowires, nanorods and the respective well-ordered arrays. The template-assisted patterning technique was successfully applied for the realization of different objectives:rnHigh-density and well-ordered arrays of hole-conducting nanorods composed of cross-lin...

  6. Turbostratic boron nitride coated on high-surface area metal oxide templates

    DEFF Research Database (Denmark)

    Klitgaard, Søren Kegnæs; Egeblad, Kresten; Brorson, M.;

    2007-01-01

    Boron nitride coatings on high-surface area MgAl2O4 and Al2O3 have been synthesized and characterized by transmission electron microscopy and by X-ray powder diffraction. The metal oxide templates were coated with boron nitride using a simple nitridation in a flow of ammonia starting from ammoniu...

  7. Amorphous coatings deposited on aluminum alloy by plasma electrolytic oxidation

    Institute of Scientific and Technical Information of China (English)

    GUAN Yong-jun; XIA Yuan

    2005-01-01

    Amorphous [Al-Si-O] coatings were deposited on aluminum alloy by plasma electrolytic oxidation (PEO). The process parameters, composition, micrograph, and mechanical property of PEO amorphous coatings were investigated. It is found that the growth rate of PEO coatings reaches 4.44 μm/min if the current density is 0.9 mA/mm2. XRD results show that the PEO coatings are amorphous in the current density range of 0.3 - 0.9mA/mm2. EDS results show that the coatings are composed of O, Si and Al elements. SEM results show that the coatings are porous. Nano indentation results show that the hardness of the coatings is about 3 - 4 times of that of the substrate, while the elastic modulus is about the same with the substrate. Furthermore, a formation mechanism of amorphous PEO coatings was proposed.

  8. Preparation of Manganese Oxide Hollow Spheres Using pH-responsive Microgels as Templates

    Institute of Scientific and Technical Information of China (English)

    Wei Zhang; Zhi-cheng Zhang

    2009-01-01

    Manganese oxide hollow spheres were prepared by a novel and facile approach using pH-responsive microgels as templates. The final products were thoroughly characterized with X-ray powder diffraction, thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared, and transmission electron microscopy. The results reveal that the shell thickness of manganese oxide hollow spheres increased with the dosage of KMnO4, which implies that a controllable and feasible strategy for manganese oxide hollow spheres prepa-ration has been established. Further studies on the microgels template showed some of them had an irreversible swelling/deswelling transition due to the uneven cross-link extent. Based on the results, a probable formation mechanism for the hollow spheres was proposed.

  9. Aluminum ions accelerated the oxidative stress of copper-mediated melanin formation

    Science.gov (United States)

    Di, Junwei; Bi, Shuping

    2003-11-01

    A comparison between the effects of aluminum and cupric ions on the dopachrome (DC) conversion and the cooperation effect of the both ions in the DOPA oxidation to melanin pathway has been studied by UV-Vis spectrophotometric method. Both aluminum and cupric ions catalyze the DC conversion reaction, which is an important step in the melanin synthesis pathway. However, cupric ions catalyze the conversion of DC to yield 5,6-dihydroxyindole-2-carboxylic acid (DHICA) but the product of DC conversion catalyzed by aluminum is 5,6-dihydroxyindole (DHI). DOPA oxidation catalyzed by aluminum and cupric ions is studied in the presence of hydrogen peroxide. The results from our experiments provide evidence that aluminum can markedly increase the oxidative stress of copper-mediated the melanin formation and influence the properties of the melanin by means of changing the ratio of DHICA/DHI in the acidic environment (pH 5.5).

  10. Quantificational Etching of AAO Template

    Institute of Scientific and Technical Information of China (English)

    Guojun SONG; Dong CHEN; Zhi PENG; Xilin SHE; Jianjiang LI; Ping HAN

    2007-01-01

    Ni nanowires were prepared by electrodeposition in porous anodized aluminum oxide (AAO) template from a composite electrolyte solution. Well-ordered Ni nanowire arrays with controllable length were then made by the partial removal of AAO using a mixture of phosphoric acid and chromic acid (6 wt pct H3PO4:1.8 wt pct H3CrO4). The images of Ni nanowire arrays were studied by scanning electron microscopy (SEM) to determine the relationship between etching time and the length of Ni nanowire arrays. The results indicate that the length of nanowires exposed from the template can be accurately controlled by controlling etching time.

  11. Effect of anneal pre-treatment of polycrystalline aluminum sheets on synthesis of highly-ordered anodic aluminum oxide membranes

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Anodic aluminum oxide (AAO) membranes with large ordered pore domains were successfully prepared by adopting the anneal pre-treatment of polycrystalline alu- minum sheets. A statistical method with Gaussian distribution was introduced to quantitatively study the size of the domain with ordered pores. The largest average area of ordered pore domains was 2.6 μm2±0.11 μm2. The corresponding AAO membrane was synthesized by aluminum sheets annealed at 893 K for 24 h.

  12. Synthesis of mesoporous cerium-zirconium mixed oxides by hydrothermal templating method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Mesoporous cerium-zirconium mixed oxides were prepared by hydrothermal method using cetyl trimethyl ammonium bromide (CTAB) as template.The effects of amount of template,pH value of solution and hydrothermal temperature on mesostructure of samples were systematically investigated.The final products were characterized by XRD,TEM,FT-IR,and BET.The results indicate that all the cerium-zirconium mixed oxides present a meso-structure.At molar ratio of n(CTAB)/n((Ce)+(Zr))=0.15,pH value of 9,and hydrothermal temperature of 120 ℃,the samples obtained possess a specific surface area of 207.9 m2/g with pore diameter of 3.70 nm and pore volume of 0.19 cm3/g.

  13. Fabrication and applications of nanocomposite structures using anodized aluminum oxide membranes

    Science.gov (United States)

    Gapin, Andrew Isaac

    As the field of nanotechnology continues to advance and device feature sizes scale down to ever smaller dimensions, it is becoming increasingly important to develop quick and efficient methods for large-scale production at the nanoscale. Creating such a template would have widespread uses in areas such as magnetic data storage, chemical sensors, and mask technology. One promising approach to realizing this goal may lie in utilizing the self-ordering behavior found in porous anodized aluminum oxide (AAO). This material offers many advantages such as the ability to customize the pore diameter and spacing and easy device integration based on its compatibility with silicon substrates. The pores of the AAO templates can be filled with many different materials via electrochemical deposition or other methods to produce numerous potential devices. In this work, current research results detailing the fabrication of AAO templates and their use in creating ˜100 nm tall CoPt, Ni, and composite Ni/CoPt nanowires is demonstrated. The synthesis of such nanostructures may ultimately be advantageous for new types of patterned magnetic recording media. The Ni nanowires exhibit relatively soft magnetic coercivity of 242 Oe, while the CoPt nanowires show a very high coercivity of at least 10.97 kOe, measured in the perpendicular direction along the nanowires axis. The composite soft magnet/hard magnet Ni/CoPt nanowires exhibit intermediate perpendicular coercivities depending on the relative amounts of Ni and CoPt. The Ni 80nm/CoPt20nm nanowires showed a coercivity of 1.96 kOe, the Ni50nm/CoPt50nm nanowires had a coercivity of 3.59 kOe, and the Ni20nm/CoPt80nm nanowires had a coercivity of 5.10 kOe. This marked decrease in the coercivity is significant because it could facilitate easier magnetic data writing. Analysis of the magnetic properties of the various nanowire structures and their dependence on the processing parameters is presented. A method for utilizing the AAO structure

  14. Nanoscale carbon tubules deposited in anodic aluminium oxide template:a study of soft x-ray transmission

    Institute of Scientific and Technical Information of China (English)

    Liu Li-Feng; Zhou Zhen-Ping; Yuan Hua-Jun; Ci Li-Jie; Liu Dong-Fang; Gao Yan; Wang Jian-Xiong; Wang Gang; Zhou Wei-Ya; Zhu Pei-Ping; Cui Ming-Qi; Zheng Lei; Zhu Jie; Zhao Yi-Dong; Song Li; Yan Xiao-Qin

    2004-01-01

    Well-aligned, catalyst-free nanoscale carbon tubules array was prepared by organic compound vapour deposition method using anodic aluminium oxide (AAO) as a template. The experiment of soft x-ray channelling in such carbon tubules array deposited in AAO template was performed at Beijing Synchrotron Radiation Facility. The transmission of x-rays in carbon tubules array with AAO template support was found even higher than that in bare AAO template at high-energy part of energy spectrum though the porous area of the former was smaller than that of the latter. A qualitative explanation is presented to interpret our results.

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

    Science.gov (United States)

    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.

  16. RF Magnetron Sputtering Aluminum Oxide Film for Surface Passivation on Crystalline Silicon Wafers

    Directory of Open Access Journals (Sweden)

    Siming Chen

    2013-01-01

    Full Text Available Aluminum oxide films were deposited on crystalline silicon substrates by reactive RF magnetron sputtering. The influences of the deposition parameters on the surface passivation, surface damage, optical properties, and composition of the films have been investigated. It is found that proper sputtering power and uniform magnetic field reduced the surface damage from the high-energy ion bombardment to the silicon wafers during the process and consequently decreased the interface trap density, resulting in the good surface passivation; relatively high refractive index of aluminum oxide film is benefic to improve the surface passivation. The negative-charged aluminum oxide film was then successfully prepared. The surface passivation performance was further improved after postannealing by formation of an SiOx interfacial layer. It is demonstrated that the reactive sputtering is an effective technique of fabricating aluminum oxide surface passivation film for low-cost high-efficiency crystalline silicon solar cells.

  17. Nanoporous Pirani sensor based on anodic aluminum oxide

    Science.gov (United States)

    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.

  18. Discharge behaviors during plasma electrolytic oxidation on aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Run [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Zhenjiang Watercraft College, Zhenjiang 212000, Jiangsu (China); Wu, Jie [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Xue, Wenbin, E-mail: xuewb@bnu.edu.cn [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Qu, Yao; Yang, Chaolin; Wang, Bin; Wu, Xianying [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

    2014-11-14

    A plasma electrolytic oxidation (PEO) process was performed on the 2024 aluminum alloy in silicate electrolyte to fabricate ceramic coatings under a constant voltage. Optical emission spectroscopy (OES) was employed to evaluate the characteristics of plasma discharge during PEO process. The plasma electron temperature and density were obtained by analyzing the spectral lines of OES, and the atomic ionization degree in discharge zone was calculated in terms of Saha thermal ionization equation. The illumination intensity of plasma discharge and the temperature in the interior of alloy were measured. Combining the surface morphology and cross-sectional microstructure with the optical emission spectra and illumination at different discharge stage, a discharge model in the growth of PEO ceramic coatings was proposed. It is found that there are two discharge modes of type A with small spark size and type B with large spark size, and the latter only appears in the intermediate stage of PEO process. The illumination intensity has a maximum value in the initial stage of oxidation with many sparks of discharge type A. The electron temperature in plasma discharge zone is about 3000 K–7000 K and atomic ionization degree of Al is about 2.0 × 10{sup −5}–7.2 × 10{sup −3}, which depend on discharge stage. The discharge type B plays a key role on the electron temperature and atomic ionization degree. The electron density keeps stable in the range of about 8.5 × 10{sup 21} m{sup −3}–2.6 × 10{sup 22} m{sup −3}. - Highlights: • The characteristics of PEO plasma discharge was evaluated by OES. • Electron temperature, concentration, atomic ionization degree were calculated. • Discharge model for the growth of PEO coatings was proposed. • Temperature in the interior of alloy during PEO process was measured.

  19. Control of zinc oxide nanowire array properties with electron-beam lithography templating for photovoltaic applications

    International Nuclear Information System (INIS)

    Hydrothermally synthesized zinc oxide nanowire arrays have been used as nanostructured acceptors in emerging photovoltaic (PV) devices. The nanoscale dimensions of such arrays allow for enhanced charge extraction from PV active layers, but the device performance critically depends on the nanowire array pitch and alignment. In this study, we templated hydrothermally-grown ZnO nanowire arrays via high-resolution electron-beam-lithography defined masks, achieving the dual requirements of high-resolution patterning at a pitch of several hundred nanometers, while maintaining hole sizes small enough to control nanowire array morphology. We investigated several process conditions, including the effect of annealing sputtered and spincoated ZnO seed layers on nanowire growth, to optimize array property metrics—branching from individual template holes and off-normal alignment. We found that decreasing template hole size decreased branching prevalence but also reduced alignment. Annealing seed layers typically improved alignment, and sputtered seed layers yielded nanowire arrays superior to spincoated seed layers. We show that these effects arose from variation in the size of the template holes relative to the ZnO grain size in the seed layer. The quantitative control of branching and alignment of the nanowire array that is achieved in this study will open new paths toward engineering more efficient electrodes to increase photocurrent in nanostructured PVs. This control is also applicable to inorganic nanowire growth in general, nanomechanical generators, nanowire transistors, and surface-energy engineering. (paper)

  20. Preparation and luminescence properties of lutetium oxide hollow spheres by a template-directed route

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted Highlights: → Uniform Lu2O3 hollow spheres have been obtained by a template-directed method. → The colloidal carbon spheres were used as template. → The main synthesis process was carried out in aqueous condition. → The Lu2O3:Ln3+ hollow spheres show intense down- and upconversion luminescence. → The hollow spheres may find potential applications in biological fields. - Abstract: Well-dispersed lutetium oxide (Lu2O3) hollow spheres have been obtained by a template-directed method with carbon spheres as template followed by a heat treatment. The main synthesis process was carried out in aqueous condition without any organic solvents, surfactant, or etching agents. SEM and TEM images reveal that the Lu2O3 hollow spheres inherit the spherical shape and good dispersion of carbon spheres, and the shells of the hollow spheres are composed of a large amount of uniform nanoparticles. The lanthanide activator ions doped Lu2O3 hollow spheres show intense down- and upconversion luminescence with different colors under ultraviolet or 980 nm light excitation, which may find potential applications in the fields of drug delivery or biological labeling. Furthermore, the luminescent mechanisms of the luminescent hollow spheres were investigated.

  1. Vertically aligned zinc oxide nanowires electrodeposited within porous polycarbonate templates for vibrational energy harvesting

    Science.gov (United States)

    Boughey, Francesca L.; Davies, Timothy; Datta, Anuja; Whiter, Richard A.; Sahonta, Suman-Lata; Kar-Narayan, Sohini

    2016-07-01

    A piezoelectric nanogenerator has been fabricated using a simple, fast and scalable template-assisted electrodeposition process, by which vertically aligned zinc oxide (ZnO) nanowires were directly grown within a nanoporous polycarbonate (PC) template. The nanowires, having average diameter 184 nm and length 12 μm, are polycrystalline and have a preferred orientation of the [100] axis parallel to the long axis. The output power density of a nanogenerator fabricated from the as-grown ZnO nanowires still embedded within the PC template was found to be 151 ± 25 mW m-3 at an impedance-matched load, when subjected to a low-level periodic (5 Hz) impacting force akin to gentle finger tapping. An energy conversion efficiency of ˜4.2% was evaluated for the electrodeposited ZnO nanowires, and the ZnO-PC composite nanogenerator was found to maintain good energy harvesting performance through 24 h of continuous fatigue testing. This is particularly significant given that ZnO-based nanostructures typically suffer from mechanical and/or environmental degradation that otherwise limits their applicability in vibrational energy harvesting. Our template-assisted synthesis of ZnO nanowires embedded within a protective polymer matrix through a single growth process is thus attractive for the fabrication of low-cost, robust and stable nanogenerators.

  2. Fractal dimension analysis of aluminum oxide particle for sandblasting dental use.

    Science.gov (United States)

    Oshida, Y; Munoz, C A; Winkler, M M; Hashem, A; Itoh, M

    1993-01-01

    Aluminum oxide particles are commonly used as a sandblasting media, particularly in dentistry, for multiple purposes including divesting the casting investment materials and increasing effective surface area for enhancing the mechanical retention strengths of succeedingly applied fired porcelain or luting cements. Usually fine aluminum oxide particles are recycled within the sandblasting machine. Ceramics such as aluminum oxides are brittle, therefore, some portions of recycling aluminum oxide particles might be brittle fractured. If fractured sandblasting particles are involved in the recycling media, it might result in irregularity metallic materials surface as well as the recycling sandblasting media itself be contaminated. Hence, it is necessary from both clinical and practical reasons to monitor the particle conditions in terms of size/shape and effectiveness of sandblasting, so that sandblasting dental prostheses can be fabricated in optimum and acceptable conditions. In the present study, the effect of recycling aluminum oxide particles on the surface texture of metallic materials was evaluated by Fractal Dimension Analysis (FDA). Every week the alumina powder was sampled and analyzed for weight fraction and contaminants. Surface texture of sandblasted standard samples was also characterized by FDA. Results indicate very little change in particle size, while the fractal dimension increased. Fractal dimension analysis showed that the aluminum oxide particle as a sandblasting media should be replaced after 30 or 40 min of total accumulated operation time.

  3. Template-Assisted Hydrothermal Growth of Aligned Zinc Oxide Nanowires for Piezoelectric Energy Harvesting Applications.

    Science.gov (United States)

    Ou, Canlin; Sanchez-Jimenez, Pedro E; Datta, Anuja; Boughey, Francesca L; Whiter, Richard A; Sahonta, Suman-Lata; Kar-Narayan, Sohini

    2016-06-01

    A flexible and robust piezoelectric nanogenerator (NG) based on a polymer-ceramic nanocomposite structure has been successfully fabricated via a cost-effective and scalable template-assisted hydrothermal synthesis method. Vertically aligned arrays of dense and uniform zinc oxide (ZnO) nanowires (NWs) with high aspect ratio (diameter ∼250 nm, length ∼12 μm) were grown within nanoporous polycarbonate (PC) templates. The energy conversion efficiency was found to be ∼4.2%, which is comparable to previously reported values for ZnO NWs. The resulting NG is found to have excellent fatigue performance, being relatively immune to detrimental environmental factors and mechanical failure, as the constituent ZnO NWs remain embedded and protected inside the polymer matrix.

  4. Passivation effects of atomic-layer-deposited aluminum oxide

    Directory of Open Access Journals (Sweden)

    Kotipalli R.

    2013-09-01

    Full Text Available Atomic-layer-deposited (ALD aluminum oxide (Al2O3 has recently demonstrated an excellent surface passivation for both n- and p-type c-Si solar cells thanks to the presence of high negative fixed charges (Qf ~ 1012−1013 cm-2 in combination with a low density of interface states (Dit. This paper investigates the passivation quality of thin (15 nm Al2O3 films deposited by two different techniques: plasma-enhanced atomic layer deposition (PE-ALD and Thermal atomic layer deposition (T-ALD. Other dielectric materials taken into account for comparison include: thermally-grown silicon dioxide (SiO2 (20 nm, SiO2 (20 nm deposited by plasma-enhanced chemical vapour deposition (PECVD and hydrogenated amorphous silicon nitride (a-SiNx:H (20 nm also deposited by PECVD. With the above-mentioned dielectric layers, Metal Insulator Semiconductor (MIS capacitors were fabricated for Qf and Dit extraction through Capacitance-Voltage-Conductance (C-V-G measurements. In addition, lifetime measurements were carried out to evaluate the effective surface recombination velocity (SRV. The influence of extracted C-V-G parameters (Qf,Dit on the injection dependent lifetime measurements τ(Δn, and the dominant passivation mechanism involved have been discussed. Furthermore we have also studied the influence of the SiO2 interfacial layer thickness between the Al2O3 and silicon surface on the field-effect passivation mechanism. It is shown that the field effect passivation in accumulation mode is more predominant when compared to surface defect passivation.

  5. A perspective of microplasma oxidation (MPO) and vapor deposition coatings in surface engineering of aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    AWAD Samir Hamid; QIAN Han-cheng

    2004-01-01

    Over the past years, great achievements have been made in the development of coating technologies for surface improvement of aluminum alloys. Despite these achievements, the role in the market strongly depends on the ability of surface coating technology under technical and economic considerations to meet the increased demands for heavy tribological applications of aluminum alloys. Microplasma oxidation (MPO) technology has recently been studied as a novel and effective means to provide thick and hard ceramic coating with improved properties such as excellent load-bearing and wear resistance properties on aluminum alloys. The present work covers the evaluation of the performances of current single and duplex coatings combining MPO, physical vapor deposition (PVD), and plasma assisted chemical vapor deposition (PACVD) coatings on aluminum alloys. It suggests that the MPO coating is a promising candidate for design engineers to apply aluminum alloys to heavy load-bearing applications. The prospective future for the research on MPO coatings is introduced as well.

  6. The Surface Science of Catalysis and More, Using Ultrathin Oxide Films as Templates: A Perspective.

    Science.gov (United States)

    Freund, Hans-Joachim

    2016-07-27

    Surface science has had a major influence on the understanding of processes at surfaces relevant to catalysis. Real catalysts are complex materials, and in order to approach an understanding at the atomic level, it is necessary in a first step to drastically reduce complexity and then systematically increase it again in order to capture the various structural and electronic factors important for the function of the real catalytic material. The use of thin oxide films as templates to mimic three-dimensional supports as such or for metal particles as well as to model charge barriers turns out to be appropriate to approach an understanding of metal-support interactions. Thin oxide films also exhibit properties in their own right that turn out to be relevant in catalysis. Thin oxide film formation may also be used to create unique two-dimensional materials. The present perspective introduces the subject using case studies and indicates possible routes to further apply this approach successfully.

  7. Interaction of ester functional groups with aluminum oxide surfaces studied using infrared reflection absorption spectroscopy.

    Science.gov (United States)

    van den Brand, J; Blajiev, O; Beentjes, P C J; Terryn, H; de Wit, J H W

    2004-07-20

    The bonding of two types of ester group-containing molecules with a set of different oxide layers on aluminum has been investigated using infrared reflection absorption spectroscopy. The different oxide layers were made by giving typical surface treatments to the aluminum substrate. The purpose of the investigation was to find out what type of ester-oxide bond is formed and whether this is influenced by changes in the composition and chemistry of the oxide. The extent by which these bonded ester molecules resisted disbondment in water or substitution by molecules capable of chemisorption was also investigated. The ester groups were found to show hydrogen bonding with hydroxyls on the oxide surfaces through their carbonyl oxygens. For all oxides, the ester groups showed the same nu(C = O) carbonyl stretching vibration after adsorption, indicating very similar bonding occurs. However, the oxides showed differences in the amount of molecules bonded to the oxide surface, and a clear relation was observed with the hydroxyl concentration present on the oxide surface, which was determined from XPS measurements. The two compounds showed differences in the free to bonded nu(C = O) infrared peak shift, indicating differences in bonding strength with the oxide surface between the two types of molecules. The bonding of the ester groups with the oxide surfaces was found to be not stable in the presence of water and also not in the presence of a compound capable of chemisorption with the aluminum oxide surface. PMID:15248718

  8. Fabrication of CoPd alloy nanowire arrays on an anodic aluminum oxide/Ti/Si substrate and their enhanced magnetic properties

    International Nuclear Information System (INIS)

    An anodic aluminum oxide/Ti/Si substrate was successfully synthesized by the anodization of an aluminum film on a Ti/Si substrate and then used as a template to grow 10 nm diameter CoPd alloy nanowires. X-ray diffraction and energy-dispersed X-ray patterns indicated that Co0.97Pd0.03 nanowire arrays with a preferential orientation of (0 0 2) were formed during electrodeposition. High coercivity (about 1700 Oe) and squareness (about 0.85) were obtained in the samples when the magnetic field was applied parallel to the axis of the nanowires; these values are much larger than those of pure Co nanowire arrays with the same diameters

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

    Science.gov (United States)

    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. Optical Anisotropy and Porosity of Anodic Aluminum Oxide Characterized by Spectroscopic Ellipsometry

    NARCIS (Netherlands)

    Kooij, E. Stefan; Wormeester, Herbert; Galca, Aurelian C.; Poelsema, Bene

    2003-01-01

    Anodic oxidation of aluminum results in a mesoporous oxide film. The thin-film geometry of our samples enables straightforward optical modeling of ellipsometry spectra of fully anodized films, using only three physically relevant parameters. The system of randomly distributed, but aligned cylindrica

  11. Fabrication of SERS-active substrates using silver nanofilm-coated porous anodic aluminum oxide for detection of antibiotics.

    Science.gov (United States)

    Chen, Jing; Feng, Shaolong; Gao, Fang; Grant, Edward; Xu, Jie; Wang, Shuo; Huang, Qian; Lu, Xiaonan

    2015-04-01

    We have developed a silver nanofilm-coated porous anodic aluminum oxide (AAO) as a surface-enhanced Raman scattering (SERS)-active substrate for the detection of trace level of chloramphenicol, a representative antibiotic in food systems. The ordered aluminum template generated during the synthesis of AAO serves as a patterned matrix on which a coated silver film replicates the patterned AAO matrix to form a 2-dimensional ordered nanostructure. We used atomic force microscopy and scanning electron microscopy images to determine the morphology of this nanosubstrate, and characterized its localized surface plasmon resonance by ultraviolet-visible reflection. We gauged the SERS effect of this nanosubstrate by confocal micro-Raman spectroscopy (782-nm laser), finding a satisfactory and consistent performance with enhancement factors of approximately 2 × 10(4) and a limit of detection for chloramphenicol of 7.5 ppb. We applied principal component analysis to determine the limit of quantification for chloramphenicol of 10 ppb. Using electromagnetic field theory, we developed a detailed mathematical model to explain the mechanism of Raman signal enhancement of this nanosubstrate. With simple sample pretreatment and separation steps, this silver nanofilm-coated AAO substrate could detect 50 ppb chloramphenicol in milk, indicating good potential as a reliable SERS-active substrate for rapid detection of chemical contaminants in agricultural and food products.

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

    Science.gov (United States)

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

    2016-11-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dongya; Dong, Guangneng, E-mail: donggn@mail.xjtu.edu.cn; Chen, Yinjuan; Zeng, Qunfeng

    2014-01-30

    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/dm{sup 2} 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.

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

    Science.gov (United States)

    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.

  15. Interface modification of organic photovoltaics by combining molybdenum oxide (MoOx) and molecular template layer

    International Nuclear Information System (INIS)

    We report discrete heterojunction small molecular organic photovoltaics (OPVs) with enhanced performance by modifying the interface using molybdenum oxide (MoOx) and molecular template layer perylene-3,4,9,10-tetracarboxylic-3,4,9,10-dianhydride (PTCDA). A large increase in open-circuit voltage was obtained in copper phthalocyanine/fullerene, i.e., CuPc/C60 and CuPc/PCBM, discrete planar heterojunction photovoltaics with an insertion of 5 nm MoOx hole transport layer at the interface between the anode electrode and the CuPc donor layer. It results from the band bending at the interface and the pinning of the highest occupied molecular orbital level of CuPc to the Fermi level of MoOx due to the defect states (oxygen vacancies) in MoOx thin films. Moreover, the short-circuit current showed an efficient improvement by inserting a 1 nm PTCDA layer at the interface between the MoOx layer and the CuPc layer. The PTCDA layer induces the growth of CuPc thin film with lying-down molecular arrangement, supporting the charge transports along the vertical direction. The power conversion efficiencies of CuPc/C60 and CuPc/PCBM discrete planar heterojunction photovoltaic devices were improved from about 0.80% to 1.50% with inserting both MoOx and PTCDA layers. The results suggest that the performance of organic discrete planar heterojunction photovoltaics could be optimized by interface modification with combining hole transport layer and molecular template layer, which are potentially suitable for other highly efficient OPVs, such as small molecular tandem OPVs. - Highlights: • Organic small molecule photovoltaics were fabricated by interface modification. • An inserted molybdenum oxide layer largely enhances open-circuit voltage. • An inserted molecular template layer dramatically improves short-circuit current. • The power conversion efficiencies are almost doubled with interface modification

  16. Phase evolution of magnetite nanocrystals on oxide supports via template-free bismuth ferrite precursor approach

    Science.gov (United States)

    Cheung, Jeffrey; Bogle, Kashinath; Cheng, Xuan; Sullaphen, Jivika; Kuo, Chang-Yang; Chen, Ying-Jiun; Lin, Hong-Ji; Chen, Chien-Te; Yang, Jan-Chi; Chu, Ying-Hao; Valanoor, Nagarajan

    2012-11-01

    This report investigates the phase evolution pathway of magnetite nanocrystal synthesis on oxide-supported substrates. A template-free phase separation approach, which exploits the thermodynamic instability of ternary perovskite BiFeO3 and inherent volatility of bismuth oxide in low oxygen pressure and high temperature is presented. The formation of an intermediate hematite nanocrystal phase is found as a key step that controls the eventual size and morphology of the magnetite nanocrystals. X-ray absorption spectra measurements and X-ray magnetic circular dichroism confirm that the spectral fingerprints of the magnetite nanocrystals match with that of bulk crystals. Magnetic measurements show that magnetic anisotropy is directly attributed to the nanocrystal morphology.

  17. Role of Amphiphilic Block Copolymer Composition on Pore Characteristics of Micelle-Templated Mesoporous Cobalt Oxide Films.

    Science.gov (United States)

    Wang, Siyang; Tangvijitsakul, Pattarasai; Qiang, Zhe; Bhaway, Sarang M; Lin, Kehua; Cavicchi, Kevin A; Soucek, Mark D; Vogt, Bryan D

    2016-04-26

    Block copolymer templating is a versatile approach for the generation of well-defined porosity in a wide variety of framework chemistries. Here, we systematically investigate how the composition of a poly(methoxy poly[ethylene glycol] methacrylate)-block-poly(butyl acrylate) (PMPEG-PBA) template impacts the pore characteristics of mesoporous cobalt oxide films. Three templates with a constant PMPEG segment length and different hydrophilic block volume fractions of 17%, 51%, and 68% for the PMPEG-PBA are cooperatively assembled with cobalt nitrate hexahydrate and citric acid. Irrespective of template composition, a spherical nanostructure is templated and elliptical mesostructures are obtained on calcination due to uniaxial contraction of the film. The average pore size increases from 11.4 ± 2.8 to 48.5 ± 4.3 nm as the length of the PBA segment increases as determined from AFM. For all three templates examined, a maximum in porosity (∼35% in all cases) and surface area is obtained when the precursor solids contain 35-45 wt % PMPEG-PBA. This invariance suggests that the total polymer content drives the structure through interfacial assembly. The composition for maximizing porosity and surface area with the micelle-templating approach results from a general decrease in porosity with increasing cobalt nitrate hexahydrate content and the increasing mechanical integrity of the framework to resist collapse during template removal/crystallization as the cobalt nitrate hexahydrate content increases. Unlike typical evaporation induced self-assembly with sol-gel chemistry, the hydrophilic/hydrophobic composition of the block copolymer template is not a critical component to the mesostructure developed with micelle-templating using metal nitrate-citric acid as the precursor. PMID:27040316

  18. Porous Spherical Cellulose Composites Coated by Aluminum (Ⅲ) Oxide and Silicone: Preparation,Characterization and Adsorption Behavior

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Porous spherical cellulose composite (PSCA) coated by aluminum (Ⅲ) oxide was prepared andmodified by organosilicone. SEM images of the surface morphology of the bead cellulose shows that it hasspherical shape and abundant porous structure on its surface. The mapping images of aluminum and silicon ofthe composite (PSCAS) present aluminum( Ⅲ ) oxide and silicone are uniformly dispersed on the surface. Theadsorption behavior of PSCAS toward metal ions was determined.

  19. Atmospheric pressure plasma enhanced chemical vapor deposition of zinc oxide and aluminum zinc oxide

    International Nuclear Information System (INIS)

    Zinc oxide (ZnO) and aluminum-doped zinc oxide (AZO) thin films were deposited via atmospheric pressure plasma enhanced chemical vapor deposition. A second-generation precursor, bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)(N,N′-diethylethylenediamine) zinc, exhibited significant vapor pressure and good stability at one atmosphere where a vaporization temperature of 110 °C gave flux ∼ 7 μmol/min. Auger electron spectroscopy confirmed that addition of H2O to the carrier gas stream mitigated F contamination giving nearly 1:1 metal:oxide stoichiometries for both ZnO and AZO with little precursor-derived C contamination. ZnO and AZO thin film resistivities ranged from 14 to 28 Ω·cm for the former and 1.1 to 2.7 Ω·cm for the latter. - Highlights: • A second generation precursor was utilized for atmospheric pressure film growth. • Addition of water vapor to the carrier gas stream led to a marked reduction of ZnF2. • Carbonaceous contamination from the precursor was minimal

  20. Characterization and Tribological Properties of Hard Anodized and Micro Arc Oxidized 5754 Quality Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    M. Ovundur

    2015-03-01

    Full Text Available This study was initiated to compare the tribological performances of a 5754 quality aluminum alloy after hard anodic oxidation and micro arc oxidation processes. The structural analyses of the coatings were performed using XRD and SEM techniques. The hardness of the coatings was determined using a Vickers micro-indentation tester. Tribological performances of the hard anodized and micro arc oxidized samples were compared on a reciprocating wear tester under dry sliding conditions. The dry sliding wear tests showed that the wear resistance of the oxide coating generated by micro arc oxidation is remarkably higher than that of the hard anodized alloy.

  1. Cerium oxide as conversion coating for the corrosion protection of aluminum

    Directory of Open Access Journals (Sweden)

    JELENA GULICOVSKI

    2013-11-01

    Full Text Available CeO2 coatings were formed on the aluminum after Al surface preparation, by dripping the ceria sol, previously prepared by forced hydrolysis of Ce(NO34. The anticorrosive properties of ceria coatings were investigated by the electrochemical impedance spectroscopy (EIS during the exposure to 0.03 % NaCl. The morphology of the coatings was examined by the scanning electron microscopy (SEM. EIS data indicated considerably larger corrosion resistance of CeO2-coated aluminum than for bare Al. The corrosion processes on Al below CeO2 coating are subjected to more pronounced diffusion limitations in comparison to the processes below passive aluminum oxide film, as the consequence of the formation of highly compact protective coating. The results show that the deposition of ceria coatings is an effective way to improve corrosion resistance for aluminum.

  2. Studies of "reactive templated grain growth" in some complex-oxide perovskites

    Science.gov (United States)

    West, David Lawrence

    This thesis details research on "reactive-templated grain growth" (RTGG) processing of complex-oxide perovskites. Four independent yet interwoven investigations are described. In the first, molten-salt synthesis yielded plate-like (˜0.2 x 5 x 5 mum) Ruddlesden-Popper (Sr3Ti 2O7) and Aurivillius (Bi4Ti3O 12 (BiT) and BaBi2Nb2O9) phases which served as "templates" in the subsequent studies. "Chemical preparation" routes were designed to produce intimately mixed, fine-grain matrix powders for the second and third investigations. A "citrate gel" method was developed for Bi1/2Na 1/2TiO3 (BNT)-based powders and a "sequential precipitation" method for PbNi1/3Nb2/3O3 - PbTiO3 (PNNT)-based powders. Both methods were original to the present investigation and resulted in dense, mum to sub-mum scale microstructures when applied to un-templated compositions. Microstructure studies of templated, chemically-prepared mixtures indicated that both Aurivillius phases behaved similarly with BNT-based matrices: An initially heterogeneous microstructure evolved towards a dense assemblage of anisometric (˜1 x 5 x 5 mum) grains. Sr3Ti 2O7 exhibited consistent behavior with both BNT and PNNT-based matrices: The microstructure evolved towards an aggregation of equi-axed, mum-scale grains with larger, isolated pores. A qualitative model was proposed to account for the behavior. It considered the excess matrix constituents after reaction to ABO3 perovskite and predicted an A-excess matrix in BNT-based mixtures templated with the Aurivillius phases and a B-excess matrix in BNT-based mixtures templated with Sr3Ti2O7. Predictions for PNNT-based matrices were less definite but not contradictory. In the final phase of the investigation, the solids formulation for BiT-templated, RTGG-processed Bi1/2Na17/40K3/40TiO 3 (BNKT) was systematically varied. This approach, original to this thesis, involved pre-reacting to well-defined alkali and bismuth titanate precursors. Use of these in different BNKT

  3. Study of defect generated visible photoluminescence in zinc oxide nano-particles prepared using PVA templates

    Energy Technology Data Exchange (ETDEWEB)

    Oudhia, A. [Department of Physics, Government V.Y.T. PG. Autonomous College, Durg, 491001 C.G. (India); Choudhary, A., E-mail: aarti.bhilai@gmail.com [Department of Physics, Government V.Y.T. PG. Autonomous College, Durg, 491001 C.G. (India); Sharma, S.; Aggrawal, S. [Department of Physics, Government V.Y.T. PG. Autonomous College, Durg, 491001 C.G. (India); Dhoble, S.J. [RTM University Nagpur, Maharashtra (India)

    2014-10-15

    Intrinsic defect generated photoluminescence (PL) in zinc oxide nanoparticles (NPs) obtained by a PVA template based wet-chemical process has been studied. A good controllability was achieved on the surface defects, structure and the morphology of ZnO NPs through the variation of solvents used in synthesis. The PL emission strongly depended on the defect structure and morphology. SEM, XRD, annealing and PL excitation studies were used to analyze the types of defects involved in the visible emission as well as the defect concentration. The mechanism for the blue, green and yellow emissions was proposed. The spectral content of the visible emission was controlled through generation/removal of defects through the shape transformation or annealing by focusing on defect origins and broad controls. - Highlights: • ZnO nanoparticles were synthesized using poly-vinyl alcohol template in various solvents. • The structure and morphology of ZnO nanoparticles were depended on dielectric constant and boiling point of solvents. • Photoluminescence properties of ZnO nanoparticles were studied. • Maximum optical absorbance and Photoluminescence intensity were found in ethanolic preparation. • ZnO nanoparticles were annealed at different temperatures for detection of defect emission.

  4. Urchin-like AlOOH nanostructures on Al microspheres grown via in-situ oxide template

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jiaquan [Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095 (United States); Estruga, Marc [Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706 (United States); Chen, Lianyi [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, Los Angeles, CA 90095 (United States); Yahata, Brennan [Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095 (United States); Choi, Hongseok [Department of Mechanical Engineering, Clemson University, Clemson, SC 29634 (United States); Li, Xiaochun, E-mail: xcli@seas.ucla.edu [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, Los Angeles, CA 90095 (United States)

    2014-10-15

    Highlights: • We present a simple, scalable method to grow urchin-like AlOOH on Al microspheres. • Al{sub 2}O{sub 3} nanoparticles from the native oxide films and self-assemble to form templates. • Urchin-like nanostructures spontaneously form and growth on the Al{sub 2}O{sub 3} templates. - Abstract: Three dimensional (3D) metal oxide hydroxide nanostructures are highly desirable for numerous applications. Here, we present a simple, scalable method to grow urchin-like AlOOH nanostructures on the surface of Al microspheres. Al nanoparticles with native oxide film were melted in molten salts, forming an immiscible materials system. During ultrasonic processing of the mixture, emulsion of micro Al droplets occurs and Al{sub 2}O{sub 3} nanoparticles form from the native oxide films and self-assemble to form in-situ nanostructured templates on the surfaces of Al microspheres. When the solidified mixture of Al spheres and salt is exposed to water, urchin-like nanostructures spontaneously form on the Al microspheres due to a heterogeneous nucleation and growth of γ-AlOOH on the Al{sub 2}O{sub 3} templates. This work could be readily extended to other metals, providing a novel and scalable method for the fabrication of urchin-like metal oxide hydroxide nanostructures on metal microspheres.

  5. Electrodeposition of Nanometer-Sized Ferric Oxide Materials in Colloidal Templates for Conversion of Light to Chemical Energy

    Directory of Open Access Journals (Sweden)

    James M. Gardner

    2011-01-01

    Full Text Available Colloidal crystal templates were prepared by gravitational sedimentation of 0.5 micron polystyrene particles onto fluorine-doped tin oxide (FTO electrodes. Scanning electron microscopy (SEM shows that the particles were close packed and examination of successive layers indicated a predominantly face-centered-cubic (fcc crystal structure where the direction normal to the substrate surface corresponds to the (111 direction. Oxidation of aqueous ferrous solutions resulted in the electrodeposition of ferric oxide into the templates. Removal of the colloidal templates yielded ordered macroporous electrodes (OMEs that were the inverse structure of the colloidal templates. Current integration during electrodeposition and cross-sectional SEM images revealed that the OMEs were about 2 μm thick. Comparative X-ray diffraction and infrared studies of the OMEs did not match a known phase of ferric oxide but suggested a mixture of goethite and hematite. The spectroscopic properties of the OMEs were insensitive to heat treatments at 300∘C. The OMEs were utilized for photoassisted electrochemical oxidation. A sustained photocurrent was observed from visible light in aqueous photoelectrochemical cells. Analysis of photocurrent action spectra revealed an indirect band gap of 1.85 eV. Addition of formate to the aqueous electrolytes resulted in an approximate doubling of the photocurrent.

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

    DEFF Research Database (Denmark)

    Goszczak, Arkadiusz Jaroslaw; Adam, Jost; Cielecki, Pawel Piotr;

    2016-01-01

    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...

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

    Science.gov (United States)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W; Nielsch, K; Goesele, U [Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Germany)

    2007-11-28

    The self-ordering behavior of anodic aluminum oxide (AAO) has been investigated for anodization of aluminum in malonic acid (H{sub 4}C{sub 3}O{sub 4}) 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 {approx}100 mA cm{sup -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 (D{sub int}) for a given anodization potential (U) during malonic acid anodization.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; White, D.P.; Snead, L.L. [Oak Ridge National Lab., TN (United States)] [and others

    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.

  10. Propagation of nonequilibrium phonons in aluminum-oxide ceramics fabricated by cold isostatic pressing

    International Nuclear Information System (INIS)

    Propagation of slightly nonequilibrium phonons in aluminum-oxide ceramics fabricated by cold isostatic pressing has been studied. Assuming that phonon propagation in ceramic grains is ballistic, we have analyzed characteristics of the phonon scattering and drawn some conclusions about the nature of grain boundaries

  11. Standard specification for nuclear-grade aluminum oxide-boron carbide composite pellets

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2005-01-01

    1.1 This specification applies to pellets composed of mixtures of aluminum oxide and boron carbide that may be ultimately used in a reactor core, for example, in neutron absorber rods. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

  12. Chinalco Joined Hands With Shenhua To Build 4 Million Tonnes of Aluminum Oxide Project in Hebei

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    In the afternoon of September 11,Governor of Hebei Province Zhang Qingwei met with the delegation led by Chinalco Chairman Ge Honglin and General Manager of Shenhua Group Ling Wen in Shijiazhuang,and attended the cooperation agreement signing ceremony for aluminum oxide project between the

  13. Plasma-enhanced Chemical Vapor Deposition of Aluminum Oxide Using Ultrashort Precursor Injection Pulses

    NARCIS (Netherlands)

    Dingemans, G.; M. C. M. van de Sanden,; Kessels, W. M. M.

    2012-01-01

    An alternative plasma-enhanced chemical vapor deposition (PECVD) method is developed and applied for the deposition of high-quality aluminum oxide (AlOx) films. The PECVD method combines a continuous plasma with ultrashort precursor injection pulses. We demonstrate that the modulation of the precurs

  14. Investigation of tin oxide nanofibers synthesized via bio-template technique

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Virender Singh, E-mail: vskundu-kuk@rediffmail.com; Dhiman, Jonny; Kumar, Suresh [Department of Electronic Science, Kurukshetra University, Kurukshetra (India); Dhiman, R. L. [Post-Graduate Department of Applied Physics, S.D. College, Ambala Cantt. 133 001 India (India)

    2015-08-28

    In the present paper tin oxide nanofibers have been by synthesized using cotton as bio-template via sol-gel route. This is comparatively a new synthesis technique. The structure and morphology of the obtained SnO{sub 2} nanofibers were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX). The optical properties of the same have been studied by using UV-Vis spectroscopy. The observed XRD pattern showed that peaks are very narrow and sharp which indicates crystalline nature of samples. SEM images gave an idea about the sample morphology and confirm that the obtained sample were nanofibers. The optical absorbance spectrum of the sample under study was recorded in UV-visible region (200nm- 800nm). The band gap of the sample was found to be 3.95 eV which is higher than their bulk counterpart.

  15. Tungsten Oxide and Polyaniline Composite Fabricated by Surfactant-Templated Electrodeposition and Its Use in Supercapacitors

    Directory of Open Access Journals (Sweden)

    Benxue Zou

    2014-01-01

    Full Text Available Composite nanostructures of tungsten oxide and polyaniline (PANI were fabricated on carbon electrode by electrocodeposition using sodium dodecylbenzene sulfonate (SDBS as the template. The morphology of the composite can be controlled by changing SDBS surfactant and aniline monomer concentrations in solution. With increasing concentration of aniline in surfactant solution, the morphological change from nanoparticles to nanofibers was observed. The nanostructured WO3/PANI composite exhibited enhanced capacitive charge storage with the specific capacitance of 201 F g−1 at 1.28 mA cm−2 in large potential window of -0.5~ 0.65 V versus SCE compared to the bulk composite film. The capacitance retained about 78% when the sweeping potential rate increased from 10 to 150 mV/s.

  16. Self-templated synthesis and thermal conductivity investigation for ultrathin perovskite oxide nanowires.

    Science.gov (United States)

    Yadav, Gautam G; Zhang, Genqiang; Qiu, Bo; Susoreny, Joseph A; Ruan, Xiulin; Wu, Yue

    2011-10-01

    The large thermal conductivity of bulk complex metal oxides such as SrTiO(3), NaCo(2)O(4), and Ca(3)Co(4)O(9) has set a barrier for the improvement of thermoelectric figure of merit and the applications of these materials in high temperature (≥1000 K) thermoelectric energy harvesting and solid-state cooling. Here, we present a self-templated synthesis approach to grow ultrathin SrTiO(3) nanowires with an average diameter of 6 nm in large quantity. The thermal conductivity of the bulk pellet made by compressing nanowire powder using spark plasma sintering shows a 64% reduction in thermal conductivity at 1000 K, which agrees well with theoretical modeling.

  17. Evolution of Surface Oxide Film of Typical Aluminum Alloy During Medium-Temperature Brazing Process

    Institute of Scientific and Technical Information of China (English)

    程方杰; 赵海微; 王颖; 肖兵; 姚俊峰

    2014-01-01

    The evolution of the surface oxide film along the depth direction of typical aluminum alloy under medium-temperature brazing was investigated by means of X-ray photoelectron spectroscopy (XPS). For the alloy with Mg content below 2.0wt%, whether under cold rolling condition or during medium-temperature brazing process, the en-richment of Mg element on the surface was not detected and the oxide film was pure Al2O3. However, the oxide film grew obviously during medium-temperature brazing process, and the thickness was about 80 nm. For the alloy with Mg content above 2.0wt%, under cold rolling condition, the original surface oxide film was pure Al2O3. However, the Mg element was significantly enriched on the outermost surface during medium-temperature brazing process, and MgO-based oxide film mixed with small amount of MgAl2O4 was formed with a thickness of about 130 nm. The alloy-ing elements of Mn and Si were not enriched on the surface neither under cold rolling condition nor during medium-temperature brazing process for all the selected aluminum alloy, and the surface oxide film was similar to that of pure aluminum, which was almost entire Al2O3.

  18. A template-free solvent-mediated synthesis of high surface area boron nitride nanosheets for aerobic oxidative desulfurization.

    Science.gov (United States)

    Wu, Peiwen; Zhu, Wenshuai; Chao, Yanhong; Zhang, Jinshui; Zhang, Pengfei; Zhu, Huiyuan; Li, Changfeng; Chen, Zhigang; Li, Huaming; Dai, Sheng

    2016-01-01

    Hexagonal boron nitride nanosheets (h-BNNs) with rather high specific surface area (SSA) are important two-dimensional layer-structured materials. Here, a solvent-mediated synthesis of h-BNNs revealed a template-free lattice plane control strategy that induced high SSA nanoporous structured h-BNNs with outstanding aerobic oxidative desulfurization performance. PMID:26502800

  19. Laser sintering of magnesia with nanoparticles of iron oxide and aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    García, L.V.; Mendivil, M.I.; Roy, T.K. Das; Castillo, G.A. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66451 (Mexico); Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66451 (Mexico); CIIDIT, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

    2015-05-01

    Highlights: • Laser sintered MgO pellets with nanoparticles of Al{sub 2}O{sub 3} and Fe{sub 2}O{sub 3}. • Characterized these pellets by XRD, SEM and XPS. • Spinel formations were observed in both cases. • Changes in morphology and structure were analyzed. - Abstract: Nanoparticles of iron oxide (Fe{sub 2}O{sub 3}, 20–40 nm) and aluminum oxide (Al{sub 2}O{sub 3}, 50 nm) were mixed in different concentrations (3, 5 and 7 wt%) in a magnesium oxide (MgO) matrix. The mixture pellet was irradiated with 532 nm output from a Q-switched Nd:YAG laser using different laser fluence and translation speed for sintering. The refractory samples obtained were analyzed using X-ray diffraction technique, scanning electron microscopy and X-ray photoelectron spectroscopy. The results showed that the samples irradiated at translation speed of 110 μm/s and energy fluence of 1.7 J/cm{sup 2} with a concentration of 5 and 7 wt% of Fe{sub 2}O{sub 3} presented the MgFe{sub 2}O{sub 4} spinel-type phase. With the addition of Al{sub 2}O{sub 3} nanoparticles, at a translation speed of 110 μm/s and energy fluence of 1.7 J/cm{sup 2}, there were the formations of MgAl{sub 2}O{sub 4} spinel phase. The changes in morphologies and microstructure due to laser irradiation were analyzed.

  20. [The color of implants of aluminum oxide ceramics].

    Science.gov (United States)

    Willmann, G

    1990-12-01

    Ceramic implants are manufactured from aluminium oxide ceramics (Al2O3) doped with magnesium oxide (MgO). The yellow or brown discoloration following gamma-sterilization does not constitute a material defect, but rather a property of the material. This chromic effect is explained in the following article. PMID:2078648

  1. Aluminum Nitride Formation From Aluminum Oxide/Phenol Resin Solid-Gel Mixture By Carbothermal Reduction Nitridation Method

    Directory of Open Access Journals (Sweden)

    Mylinh Dang Thy

    2015-06-01

    Full Text Available Hexagonal and cubic crystalline aluminum nitride (AlN particles were successfully synthesized using phenol resin and alpha aluminum oxide (α-Al2O3 as precursors through new solid-gel mixture and carbothermal reduction nitridaton (CRN process with molar ratio of C/Al2O3 = 3. The effect of reaction temperature on the decomposition of phenol resin and synthesis of hexagonal and cubic AlN were investigated and the reaction mechanism was also discussed. The results showed that α-Al2O3 powder in homogeneous solid-gel precursor was easily nitrided to yield AlN powder during the carbothermal reduction nitridation process. The reaction temperature needed for a complete conversion for the precursor was about 1700°C, which much lower than that when using α-Al2O3 and carbon black as starting materials. To our knowledge, phenol resin is the first time to be used for synthesizing AlN powder via carbothermal reduction and nitridation method, which would be an efficient, economical, cheap assistant reagent for large scale synthesis of AlN powder.

  2. Modelling the growth process of porous aluminum oxide film during anodization

    Science.gov (United States)

    Aryslanova, E. M.; Alfimov, A. V.; Chivilikhin, S. A.

    2015-11-01

    Currently it has become important for the development of metamaterials and nanotechnology to obtain regular self-assembled structures. One such structure is porous anodic alumina film that consists of hexagonally packed cylindrical pores. In this work we consider the anodization process, our model takes into account the influence of layers of aluminum and electrolyte on the rate of growth of aluminum oxide, as well as the effect of surface diffusion. In present work we consider those effects. And as a result of our model we obtain the minimum distance between centers of alumina pores in the beginning of anodizing process.

  3. The oxidation of aluminum at high temperature studied by Thermogravimetric Analysis and Differential Scanning Calorimetry.

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Luminescence properties of oxide films formed by anodization of aluminum in 12-tungstophosphoric acid

    International Nuclear Information System (INIS)

    In this paper, we have investigated luminescence properties of oxide films formed by anodization of aluminum in 12-tungstophosphoric acid. For the first time we have measured weak luminescence during anodization of aluminum in this electrolyte (so-called galvanoluminescence GL) and showed that there are wide GL bands in the visible region of the spectrum and observed two dominant spectral peaks. The first one is at about 425 nm, and the second one shifts with anodization voltage. As the anodization voltage approaches the breakdown voltage, a large number of sparks appear superimposed on the anodic GL. Several intensive band peaks were observed under breakdown caused by electron transitions in W, P, Al, O, H atoms. Furthermore, photoluminescence (PL) of anodic oxide films and anodic-spark formed oxide coatings were performed. In both cases wide PL bands in the range from 320 nm to 600 nm were observed.

  5. Combined flame and electrodeposition synthesis of energetic coaxial tungsten-oxide/aluminum nanowire arrays.

    Science.gov (United States)

    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. PMID:23899165

  6. Magnetic studies of mesoporous nanostructured iron oxide materials synthesized by one-step soft-templating.

    Science.gov (United States)

    Jin, Jing; Hines, William A; Kuo, Chung-Hao; Perry, David M; Poyraz, Altug S; Xia, Yan; Zaidi, Taha; Nieh, Mu-Ping; Suib, Steven L

    2015-07-14

    A combined magnetization and (57)Fe spin-echo nuclear magnetic resonance (NMR) study has been carried out on mesoporous nanostructured materials consisting of the magnetite (Fe3O4) and maghemite (γ-Fe2O3) phases. Two series of samples were synthesized using a recently developed one-step soft-templating approach with systematic variations in calcination temperature and reaction atmosphere. Nuclear magnetic resonance has been shown to be a valuable tool for distinguishing between the two magnetic iron oxide spinel phases, Fe3O4 and γ-Fe2O3, on the nanoscale as well as monitoring phase transformation resulting from oxidation. For the Fe3O4 and γ-Fe2O3 phases, peaks in the NMR spectra are attributed to Fe in the tetrahedral (A) sites and octahedral (B) sites. The magnetic field dependence of the peaks was observed and confirmed the site assignments. Fe3O4 on a nanoscale readily oxidizes to form γ-Fe2O3 and this was clearly evident in the NMR spectra. As evidenced by transmission electron microscope (TEM) images, the porous mesostructure for the iron oxide materials is formed by a random close-packed aggregation of nanoparticles; correspondingly, superparamagnetic behavior was observed in the magnetic measurements. Although X-ray diffraction (XRD) shows the spinel structure for the Fe3O4 and γ-Fe2O3 phases, unlike NMR, it is difficult to distinguish between the two phases with XRD. Nitrogen sorption isotherms characterize the mesoporous structures of the materials, and yield BET surface area values and limited BJH pore size distribution curves. PMID:26067028

  7. Magnetic studies of mesoporous nanostructured iron oxide materials synthesized by one-step soft-templating.

    Science.gov (United States)

    Jin, Jing; Hines, William A; Kuo, Chung-Hao; Perry, David M; Poyraz, Altug S; Xia, Yan; Zaidi, Taha; Nieh, Mu-Ping; Suib, Steven L

    2015-07-14

    A combined magnetization and (57)Fe spin-echo nuclear magnetic resonance (NMR) study has been carried out on mesoporous nanostructured materials consisting of the magnetite (Fe3O4) and maghemite (γ-Fe2O3) phases. Two series of samples were synthesized using a recently developed one-step soft-templating approach with systematic variations in calcination temperature and reaction atmosphere. Nuclear magnetic resonance has been shown to be a valuable tool for distinguishing between the two magnetic iron oxide spinel phases, Fe3O4 and γ-Fe2O3, on the nanoscale as well as monitoring phase transformation resulting from oxidation. For the Fe3O4 and γ-Fe2O3 phases, peaks in the NMR spectra are attributed to Fe in the tetrahedral (A) sites and octahedral (B) sites. The magnetic field dependence of the peaks was observed and confirmed the site assignments. Fe3O4 on a nanoscale readily oxidizes to form γ-Fe2O3 and this was clearly evident in the NMR spectra. As evidenced by transmission electron microscope (TEM) images, the porous mesostructure for the iron oxide materials is formed by a random close-packed aggregation of nanoparticles; correspondingly, superparamagnetic behavior was observed in the magnetic measurements. Although X-ray diffraction (XRD) shows the spinel structure for the Fe3O4 and γ-Fe2O3 phases, unlike NMR, it is difficult to distinguish between the two phases with XRD. Nitrogen sorption isotherms characterize the mesoporous structures of the materials, and yield BET surface area values and limited BJH pore size distribution curves.

  8. Effects of aluminum and extremely low frequency electromagnetic radiation on oxidative stress and memory in brain of mice.

    Science.gov (United States)

    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.

  9. The thickness of native oxides on aluminum alloys and single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Evertsson, J., E-mail: jonas.evertsson@sljus.lu.se [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden); Bertram, F. [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden); Zhang, F. [KTH Royal Institute of Technology, Department of Chemistry, Division of Surface and Corrosion Science, Drottning Kristinas Vg 51, 100 44 Stockholm (Sweden); Rullik, L.; Merte, L.R.; Shipilin, M. [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden); Soldemo, M.; Ahmadi, S. [KTH Royal Institute of Technology, ICT, Material Physics, 16440 Kista (Sweden); Vinogradov, N.; Carlà, F. [ESRF, B.P. 220, 38043 Grenoble (France); Weissenrieder, J.; Göthelid, M. [KTH Royal Institute of Technology, ICT, Material Physics, 16440 Kista (Sweden); Pan, J. [KTH Royal Institute of Technology, Department of Chemistry, Division of Surface and Corrosion Science, Drottning Kristinas Vg 51, 100 44 Stockholm (Sweden); Mikkelsen, A. [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden); Nilsson, J.-O. [Sapa Technology, Kanalgatan 1, 612 31 Finspång (Sweden); Lundgren, E. [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden)

    2015-09-15

    Highlights: • We have determined the native oxide film thickness on several Al samples. • The results obtained from XRR and XPS show excellent agreement. • The results obtained from EIS show consistently thinner oxide films. • The oxides on the alloys are thicker than the oxides on the single crystals. - Abstract: We present results from measurements of the native oxide film thickness on four different industrial aluminum alloys and three different aluminum single crystals. The thicknesses were determined using X-ray reflectivity, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. In addition, atomic force microscopy was used for micro-structural studies of the oxide surfaces. The reflectivity measurements were performed in ultra-high vacuum, vacuum, ambient, nitrogen and liquid water conditions. The results obtained using X-ray reflectivity and X-ray photoelectron spectroscopy demonstrate good agreement. However, the oxide thicknesses determined from the electrochemical impedance spectroscopy show a larger discrepancy from the above two methods. In the present contribution the reasons for this discrepancy are discussed. We also address the effect of the substrate type and the presence of water on the resultant oxide thickness.

  10. Positron annihilation study of iron oxide nanoparticles in mesoporous silica MCM-41 template

    International Nuclear Information System (INIS)

    The subject of investigation were the samples obtained by impregnation of MCM-41 template with an aqueous solution prepared from Fe(NO3)3·9H2O. As a result of such a procedure, iron oxides deposits on MCM-41 were formed. The Moessbauer studies revealed an occurrence of Fe3O4 nanocrystallites in the both ferri- and superparamagnetic states. Almost 80% small particles exist in a paramagnetic state. The positron annihilation lifetime spectroscopy (PALS) spectra were measured in air or in vacuum. The long-lived ortho-positronium (o-Ps) components and their intensities are time dependent due to air molecules interaction with iron oxide nanocrystallites and silica walls surfaces. The adsorption of air on the nanocrystallites surface causes a total screening of their surface and a raise of the o-Ps lifetime values. Observed anti-quenching effect is a result of competition of two phenomena: practically switching off a pick-off mechanism related to interaction of o-Ps with magnetite nanoparticles and considerably weaker usual quenching by paramagnetic oxygen molecules. (authors)

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

    Directory of Open Access Journals (Sweden)

    Chun Zhao

    2014-10-01

    Full Text Available 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.

  12. The Relationship Between Ambiently Formed Oxides and the Tribological Behavior of Aluminum Bronze

    Science.gov (United States)

    Poggie, Robert Andre

    1992-01-01

    The relationship between ambiently formed oxides and the tribological behavior of aluminum bronze has been investigated. As the aluminum content of Al-bronze increases from zero to eight weight percent, the mechanical properties, oxidation kinetics, and tribological behavior of the alloy are significantly affected. This research has shown that the friction and wear behavior of Al-bronze depends primarily on the composition and mechanical stability of the ambiently formed surface oxide. Adhesive transfer of Al-bronze to the slider counterfaces increased with increasing aluminum content which corresponded to increased damage to the alloy surfaces and the formation of wear debris. The majority of surface damage (plastic deformation and galling) of the Cu-4 and 6 w/o Al alloys occurred during the initial portion (run-in) of wear testing. The Cu-1 w/o Al alloy wore via an oxidative wear mechanism throughout the course of wear testing. Galling, severe plastic deformation, the formation of metallic wear debris, and adhesive transfer were not observed for the Cu-1 AL w/o alloy. XPS and SEM analysis of the Cu-1 w/o Al alloy showed the worn surfaces to consist of a smooth and adherent Cu_2O layer. Long term ambient oxidation of the Cu-4 and 6 w/o Al alloys resulted in a layered oxide structure with Cu(OH)_2 at the surface followed by CuO, Cu_2O, Al_2O_3, and, lastly, the metallic substrate. The differences in elastic moduli, crystal structures, and composition between the copper alloy and the Al _2O_3 enriched surface oxide decreases the mechanical integrity of the surface oxide. The tensile and compressive stresses generated at the surface of the Al-bronze samples via frictional interaction with the opposing slider is sufficient to cause a large differential in strain across the oxide-metal interface and disruption of the brittle, Al_2O _3 enriched surface oxide. The exposed metal immediately repassivates itself by reforming a surface oxide or forming an adhesive bond with

  13. Large pore volume mesoporous aluminum oxide synthesized via nano-assembly

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A new nano-assembly approach has been proposed for the preparation of macropore volume mesoporous aluminum oxide supports. Secondary nano-assembly and a frame structure mechanism for large pore volume mesoporous supports have been proposed. In a primary nano-assembly supersoluble micelle,aluminum hydroxide nanoparticles were precipitated in situ in surfactants with a volume balance (VB) less than 1,followed by secondary nano-assembly in linear and cylindrical shapes. The secondary nano-assembly of cylindrical aluminum hydroxides was calcined to form nano cylindrical aluminum oxides. For the formation of macropore volume mesoporous supports,we utilized a frame structure mechanism of mesoporous support,in which the exterior surface of the carrier may not be continuous. This macropore volume support has been used for the hydrotreatment of a residual oil catalyst,which possesses the following physical characteristics:pore volume 1.8―2.7 mL·g-1,specific surface area 180―429 m2·g-1,average pore diameter 17―57 nm,average pore diameter more than 10 nm (81%―94%),porosity 87%―93%,and crush strength 7.7―25 N·mm-1.

  14. Modeling of oxidation of aluminum nanoparticles by using Cabrera Mott Model

    Science.gov (United States)

    Ramazanova, Zamart; Zyskin, Maxim; Martirosyan, Karen

    2012-10-01

    Our research focuses on modeling new Nanoenergetic Gas-Generator (NGG) formulations that rapidly release a large amount of gaseous products and generates shock and pressure waves. Nanoenergetic thermite reagents include mixtures of Al and metal oxides such as bismuth trioxide and iodine pentoxide. The research problem is considered a spherically symmetric case and used the Cabrera Mott oxidation model to describe the kinetics of oxide growth on spherical Al nanoparticles for evaluating reaction time which a process of the reaction with oxidizer happens on the outer part of oxide layer of aluminum ions are getting in contact with an oxidizing agent and react. We assumed that a ball of Al of radius 20 to 50 nm is covered by a thin oxide layer 2-4 nm and is surrounded by abundant amount of oxygen stored by oxidizers. The ball is rapidly heated up to ignition temperature to initiate self-sustaining oxidation reaction. As a result highly exothermic reaction is generated. In the oxide layer of excess concentrations of electrons and ions are dependent on the electric field potential with the corresponding of the Gibbs factors and that it conducts to the solution of a nonlinear Poisson equation for the electric field potential in a moving boundary domain. Motion of the boundary is determined by the gradient of a solution on the boundary. We investigated oxidation model numerically, using the COMSOL software utilizing finite element analysis. The computing results demonstrate that oxidation rate increases with the decreasing particle radius.

  15. Effects of Iron and Aluminum Oxides and Kaolinite on Adsorpion and Activities on Invertase

    Institute of Scientific and Technical Information of China (English)

    HUANGQIAOYUN; JIANGMINGHUA; 等

    1998-01-01

    Experiments were conducted to study the influences of synthetic bayerite,non-crystalline aluminum oxide(N-AlOH) ,geoethite,non-crystalline iron oxide (N-FeOH) and kaolinite on the adsorption,activity,kinetics and thermal stability of invertase.Adsorption of invertase on iron,aluminum oxides fitted Langmuir equation,The amount of invertase held on the minerals followed the sequence kaolinite>goethite>N-AlOH>bayerite>N-FeOH.No correlation was found between enzyme adsorption and the specific surface area of minerals exmined.The differences in the surface structure of minerals and the arrangement of enzymatic molecules on mineral surfaces led to the different capacities of minerals for enzyme adsorption. The adsorption of invertase on bayerite,N-AlOH,goethite ,H-FeOH and kaolinite was differently affected by pH.The order for the activity of invertase adsorbed on minerals was N-FeOH>N-AlOH>bayerite> goethite> kalinite.The inhibition effect of minerals on enzyme activity was kaolinite> crystalline oxides> non -crystalline oxides.The pH optimum of iron oxide-and aluminum oxide-invertase complexes was sililar to that of free enzyme(pH4.0),whereas the pH optimum of kaolinite-invertase complex was one pH unit highr than that of free enzyme.The affinity to substrate and the maximum reaction velocity as well as the thermal stability of combined inverthase were lower than those of the free enzyme.

  16. Standard test methods for chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade aluminum oxide and aluminum oxide-boron carbide composite pellets

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1994-01-01

    1.1 These test methods cover procedures for the chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade aluminum oxide and aluminum oxide-boron carbide composite pellets to determine compliance with specifications. 1.2 The analytical procedures appear in the following order: Sections Boron by Titrimetry 7 to 13 Separation of Boron for Mass Spectrometry 14 to 19 Isotopic Composition by Mass Spectrometry 20 to 23 Separation of Halides by Pyrohydrolysis 24 to 27 Fluoride by Ion-Selective Electrode 28 to 30 Chloride, Bromide, and Iodide by Amperometric Microtitrimetry 31 to 33 Trace Elements by Emission Spectroscopy 34 to 46 1.3 The values stated in SI units are to be regarded as the standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. (F...

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

    Science.gov (United States)

    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. Interactions between nitric oxide and plant hormones in aluminum tolerance

    OpenAIRE

    He, Huyi; He, Longfei; Gu, Minghua

    2012-01-01

    Nitric oxide (NO) is involved, together with plant hormones, in the adaptation to Al stress in plants. However, the mechanism by which NO and plant hormones interplay to improve Al tolerance are still unclear. We have recently shown that patterns of plant hormones alteration differ between rye and wheat under Al stress. NO may enhance Al tolerance by regulating hormonal equilibrium in plants, as a regulator of plant hormones signaling. In this paper, some unsolved issues are discussed based o...

  19. Effect of conditions of thermal treatment on the porous structure of an aluminum oxide-containing nanofibrous aerogel

    Science.gov (United States)

    Markova, E. B.; Krasil'nikova, O. K.; Grankina, T. Yu.; Serov, Yu. M.

    2016-08-01

    The effect the conditions of thermal treatment have on a specific surface and the number of primary adsorption centers is studied. The relationship between changing adsorption characteristics and changes in the structure of nanofibrous aluminum oxide is considered.

  20. Computer simulation of the photoluminescence of nanostructured aluminum oxide excited with pulsed synchrotron radiation

    OpenAIRE

    Kortov, V. S.; Spiridonova, T. V.; Zvonarev, S. V.

    2013-01-01

    An algorithm and a program are developed to calculate the photoluminescence (PL) parameters for bulk single-crystal and nanoscale dielectrics excited with pulsed synchrotron radiation. The luminescence spectra of F and F+centers and the PL decay kinetics in single-crystal and nanoscale aluminum-oxide samples containing oxygen anion vacancies are calculated for various nanoparticle sizes. It is shown that a noticeable broadening of the bands and a decrease in the afterglow time is observed for...

  1. Radial Combustion Propagation in Iron(III) Oxide/Aluminum Thermite Mixtures

    OpenAIRE

    Durães, Luísa; Campos, José; Portugal, António

    2006-01-01

    The self-sustained thermite reaction between iron oxide (Fe2O3) and aluminum is a classical source of energy. In this work the radial combustion propagation on thin circular samples of stoichiometric and over aluminized Fe2O3/Al thermite mixtures is studied. The radial geometry allows an easy detection of sample heterogeneities and the observation of the combustion behavior in their vicinity. The influence of factors like reactant mixtures stoichiometry, samples green density and system geome...

  2. Structure and properties of ceramic coatings formed on aluminum alloys by microarc oxidation

    Institute of Scientific and Technical Information of China (English)

    LIU Wan-hui; BAO Ai-lian; LIU Rong-xiang; WU Wan-liang

    2006-01-01

    The thick and hard ceramic coatings were deposited on 2024 Al alloy by microarc oxidation in the electrolytic solution.Microstructure, phase composition and wear resistance of the oxide coatings were investigated by SEM, XRD and friction and wear tester. The microhardness and thickness of the oxide coatings were measured. The results show that the ceramic coating is mainly composed of α-Al2O3 and γ-Al2O3. During oxidation, the temperature in the microarc discharge channel is very high to make the local coating molten. From the surface to interior of the coating, microhardness increases gradually. The microhardness of the ceramic coating is HV1 800, and the microarc oxidation coatings greatly improve the antiwear properties of aluminum alloys.

  3. Fabrication and optical properties of platinum nanowire arrays on anodic aluminium oxide templates

    Institute of Scientific and Technical Information of China (English)

    高铁仁; 陈子瑜; 彭勇; 李发伸

    2002-01-01

    Arrays of Pt nanowires, fabricated by electrodepositing Pt metal into nanoporous anodic aluminium oxide (AAO)templates, exhibit a preferable optical absorption band in the ultraviolet-visible (UV-VIS) spectra and present a blueshift as the wire aspect ratio increases or its radius decreases. This type of optical property of Pt nanowire/porous alumina composites has been theoretically explored using Maxwell-Garnett (MG) effective medium theory. The MG theory,however, is only applicable to nanowires with an infinitesimally small radius relative to the wavelength of an incident light. The nanowire radius is controlled by the pore radius of the host alumina, which depends on anodizing conditions such as the selected electrolyte, anodizing time, temperature and voltage. The nanowire aspect ratios depend on the amount of Pt deposited into the nanopores of AAO films. The optical absorption properties of the arrays of Pt nanowires with diameters of 24, 55 and 90nm have been investigated by the UV-VIS spectra, which show that the extinction maximum (λmax) shifts to shorter wavelength side as the wire aspect ratio increases or its radius decreases.The results are qualitatively consistent with those calculated based on the MG theory.

  4. Nanowires: properties, applications and synthesis via porous anodic aluminium oxide template

    Indian Academy of Sciences (India)

    Jaya Sarkar; Gobinda Gopal Khan; A Basumallick

    2007-06-01

    Quasi one-dimensional nanowires possess unique electrical, electronic, thermoelectrical, optical, magnetic and chemical properties, which are different from that of their parent counterpart. The physical properties of nanowires are influenced by the morphology of the nanowires, diameter dependent band gap, carrier density of states etc. Nanowires hold lot of promises for different applications. Basic electronic devices like junction diodes, transistors, FETs and logic gates can be fabricated by using semiconductor and superlattice nanowires. Thermoelectric cooling system can be fabricated by using metallic nanowires. Semiconductor nanowire junctions can be used for different opto-electronic applications. Moreover, periodic arrays of magnetic nanowires hold high potential for recording media application. Nanowires are also potential candidates for sensor and bio-medical applications. In the present article, the physical and chemical properties of nanowires along with their probable applications in different fields have been reviewed in detail. The review also includes highlights of the synthesis of nanowires via porous anodic aluminium oxide template since the technique is simple, cost-effective and a low temperature technique.

  5. Fabrication of a Zinc Aluminum Oxide Nanowire Array Photoelectrode for a Solar Cell Using a High Vacuum Die Casting Technique

    Directory of Open Access Journals (Sweden)

    Chin-Guo Kuo

    2014-01-01

    Full Text Available Zinc aluminum alloy nanowire was fabricated by the vacuum die casting. Zinc aluminum alloy was melted, injected into nanomold under a hydraulic pressure, and solidified as nanowire shape. Nanomold was prepared by etching aluminum sheet with a purity of 99.7 wt.% in oxalic acid solution. A nanochannel within nanomold had a pore diameter of 80 nm and a thickness of 40 μm. Microstructure and characteristic analysis of the alumina nanomold and zinc-aluminum nanowire were performed by scanning electron microscope, X-ray diffraction analysis, and energy dispersive X-ray spectroscopy. Zinc aluminum oxide nanowire array was produced using the thermal oxidation method and designed for the photoelectrode application.

  6. Iron oxide nanoparticle layer templated by polydopamine spheres: a novel scaffold toward hollow-mesoporous magnetic nanoreactors.

    Science.gov (United States)

    Huang, Liang; Ao, Lijiao; Xie, Xiaobin; Gao, Guanhui; Foda, Mohamed F; Su, Wu

    2015-01-14

    Superparamagnetic iron oxide nanoparticle layers with high packing density and controlled thickness were in situ deposited on metal-affinity organic templates (polydopamine spheres), via one-pot thermal decomposition. The as synthesized hybrid structure served as a facile nano-scaffold toward hollow-mesoporous magnetic carriers, through surfactant-assisted silica encapsulation and its subsequent calcination. Confined but accessible gold nanoparticles were successfully incorporated into these carriers to form a recyclable catalyst, showing quick magnetic response and a large surface area (642.5 m(2) g(-1)). Current nano-reactors exhibit excellent catalytic performance and high stability in reduction of 4-nitrophenol, together with convenient magnetic separability and good reusability. The integration of compact iron oxide nanoparticle layers with programmable polydopamine templates paves the way to fabricate magnetic-response hollow structures, with high permeability and multi-functionality. PMID:25437262

  7. Effect of aluminum oxide on the compressive strength of pellets

    Institute of Scientific and Technical Information of China (English)

    Jian-liang Zhang; Zhen-yang Wang; Xiang-dong Xing; Zheng-jian Liu

    2014-01-01

    Analytical-reagent-grade Al2O3 was added to magnetite ore during the process of pelletizing, and the methods of mercury intru-sion, scanning electron microscopy, and image processing were used to investigate the effect of Al2O3 on the compressive strength of the pellets. The results showed that, as the Al2O3 content increased, the compressive strength of the pellets increased slightly and then decreased gradually. When a small amount of Al2O3 was added to the pellets, the Al2O3 combined with fayalite (2FeO·SiO2) and the aluminosilicate (2FeO·2Al2O3·5SiO2) was generated, which releases some iron oxide and reduces the inhibition of fayalite to the solid phase of consolidation. When Al2O3 increased sequentially, high melting point of Al2O3 particles hinder the oxidation of Fe3O4 and the recrystallization of Fe2O3, making the internal porosity of the pellets increase, which leads to the decrease in compressive strength of the pellets.

  8. Systematic review of potential health risks posed by pharmaceutical, occupational and consumer exposures to metallic and nanoscale aluminum, aluminum oxides, aluminum hydroxide and its soluble salts

    Science.gov (United States)

    Willhite, Calvin C.; Karyakina, Nataliya A.; Yokel, Robert A.; Yenugadhati, Nagarajkumar; Wisniewski, Thomas M.; Arnold, Ian M. F.; Momoli, Franco; Krewski, Daniel

    2016-01-01

    Aluminum (Al) is a ubiquitous substance encountered both naturally (as the third most abundant element) and intentionally (used in water, foods, pharmaceuticals, and vaccines); it is also present in ambient and occupational airborne particulates. Existing data underscore the importance of Al physical and chemical forms in relation to its uptake, accumulation, and systemic bioavailability. The present review represents a systematic examination of the peer-reviewed literature on the adverse health effects of Al materials published since a previous critical evaluation compiled by Krewski et al. (2007). Challenges encountered in carrying out the present review reflected the experimental use of different physical and chemical Al forms, different routes of administration, and different target organs in relation to the magnitude, frequency, and duration of exposure. Wide variations in diet can result in Al intakes that are often higher than the World Health Organization provisional tolerable weekly intake (PTWI), which is based on studies with Al citrate. Comparing daily dietary Al exposures on the basis of “total Al” assumes that gastrointestinal bioavailability for all dietary Al forms is equivalent to that for Al citrate, an approach that requires validation. Current occupational exposure limits (OELs) for identical Al substances vary as much as 15-fold. The toxicity of different Al forms depends in large measure on their physical behavior and relative solubility in water. The toxicity of soluble Al forms depends upon the delivered dose of Al+3 to target tissues. Trivalent Al reacts with water to produce bidentate superoxide coordination spheres [Al(O2)(H2O4)+2 and Al(H2O)6+3] that after complexation with O2•−, generate Al superoxides [Al(O2•)](H2O5)]+2. Semireduced AlO2• radicals deplete mitochondrial Fe and promote generation of H2O2, O2•− and OH•. Thus, it is the Al+3-induced formation of oxygen radicals that accounts for the oxidative damage that

  9. Systematic review of potential health risks posed by pharmaceutical, occupational and consumer exposures to metallic and nanoscale aluminum, aluminum oxides, aluminum hydroxide and its soluble salts.

    Science.gov (United States)

    Willhite, Calvin C; Karyakina, Nataliya A; Yokel, Robert A; Yenugadhati, Nagarajkumar; Wisniewski, Thomas M; Arnold, Ian M F; Momoli, Franco; Krewski, Daniel

    2014-10-01

    oxidative damage that leads to intrinsic apoptosis. In contrast, the toxicity of the insoluble Al oxides depends primarily on their behavior as particulates. Aluminum has been held responsible for human morbidity and mortality, but there is no consistent and convincing evidence to associate the Al found in food and drinking water at the doses and chemical forms presently consumed by people living in North America and Western Europe with increased risk for Alzheimer's disease (AD). Neither is there clear evidence to show use of Al-containing underarm antiperspirants or cosmetics increases the risk of AD or breast cancer. Metallic Al, its oxides, and common Al salts have not been shown to be either genotoxic or carcinogenic. Aluminum exposures during neonatal and pediatric parenteral nutrition (PN) can impair bone mineralization and delay neurological development. Adverse effects to vaccines with Al adjuvants have occurred; however, recent controlled trials found that the immunologic response to certain vaccines with Al adjuvants was no greater, and in some cases less than, that after identical vaccination without Al adjuvants. The scientific literature on the adverse health effects of Al is extensive. Health risk assessments for Al must take into account individual co-factors (e.g., age, renal function, diet, gastric pH). Conclusions from the current review point to the need for refinement of the PTWI, reduction of Al contamination in PN solutions, justification for routine addition of Al to vaccines, and harmonization of OELs for Al substances.

  10. Graphene oxide-templated synthesis of ultrathin or tadpole-shaped au nanowires with alternating hcp and fcc domains.

    Science.gov (United States)

    Huang, Xiao; Li, Shaozhou; Wu, Shixin; Huang, Yizhong; Boey, Freddy; Gan, Chee Lip; Zhang, Hua

    2012-02-14

    Ultrathin Au nanowires (AuNWs) and tadpole-shaped nanowires are synthesized on graphene oxide (GO) sheet templates. For the first time, 1.6 nm-diameter AuNWs are shown to contain hexagonal close-packed (hcp) crystal domains, and the tadpole-shaped nanowires exhibit alternating sets of hcp and face-centered cubic (fcc) structures, associated with variation in wire thickness.

  11. Sorption of phenanthrene by dissolved organic matter and its complex with aluminum oxide nanoparticles

    International Nuclear Information System (INIS)

    Intent of this study was to explore the potential application of polymerin, the polymeric, dissolved organic matter fraction from olive oil wastewaters, in technologies aimed at remediating hydrophobic organic compounds (HOCs) point-source pollution. Phenanthrene binding with polymerin was investigated. Moreover, the effect of addition of micro and nanoscale aluminum oxides (Al2O3) was studied, as well as sorption of polymerin on the oxides. Phenanthrene binding capacity by polymerin was notably higher than the sorption capacities for both types of Al2O3 particles. Polymerin sorption on nanoparticles was nearly 100 times higher than microparticles. In a three-phase system, using microparticles, higher phenanthrene sorption was found by adding into water polymerin, oxides and phenanthrene simultaneously. In contrast, using nanoparticles, a considerable enhancement of phenanthrene sorption was shown by adding phenanthrene to a pre-formed and dried polymerin-oxide complex. These findings support the application of polymerin, especially associated with Al2O3 nanoparticles, in remediation of water contaminated with HOCs. This work highlights the significant role of nanoparticles. - Size of aluminum oxides significantly affects sorption of polymerin and phenanthrene

  12. Reaction behavior between the oxide film of LY12 aluminum alloy and the flux

    Institute of Scientific and Technical Information of China (English)

    薛松柏; 董健; 吕晓春; 顾文华

    2004-01-01

    In this paper, the brazing mechanism of LY12 aluminum alloy at middle range temperature was presented. The CsF-AlF3 non-corrosive flux was utilized to remove the complex oxide film on the surface of LY12 aluminum alloy. The results revealed that the oxide film was removed by the improved CsF-AlF3 flux accompanied with the occurrence of reaction as well as dissolution and the compounds CsF played an important role to remove the oxide film. Actually, the high activity of flux, say, the ability to remove the oxide film, was due to the presence of the compounds, such as NH4F,NH4AlF4 and composite molten salt. The production of HF was the key issue to accelerate the reaction and enhance to eliminate the oxide film by dissolution. It was found that the rare earth element La at small percentage was not enriched at the interface. Moreover, the rare earth fluoride enhanced the dissolution behavior.

  13. High performance In2O3 thin film transistors using chemically derived aluminum oxide dielectric

    KAUST Repository

    Nayak, Pradipta K.

    2013-07-18

    We report high performance solution-deposited indium oxide thin film transistors with field-effect mobility of 127 cm2/Vs and an Ion/Ioff ratio of 106. This excellent performance is achieved by controlling the hydroxyl group content in chemically derived aluminum oxide (AlOx) thin-film dielectrics. The AlOx films annealed in the temperature range of 250–350 °C showed higher amount of Al-OH groups compared to the films annealed at 500 °C, and correspondingly higher mobility. It is proposed that the presence of Al-OH groups at the AlOx surface facilitates unintentional Al-doping and efficient oxidation of the indium oxide channel layer, leading to improved device performance.

  14. Application of diffusion barriers to the refractory fibers of tungsten, columbium, carbon and aluminum oxide

    Science.gov (United States)

    Douglas, F. C.; Paradis, E. L.; Veltri, R. D.

    1973-01-01

    A radio frequency powered ion-plating system was used to plate protective layers of refractory oxides and carbide onto high strength fiber substrates. Subsequent overplating of these combinations with nickel and titanium was made to determine the effectiveness of such barrier layers in preventing diffusion of the overcoat metal into the fibers with consequent loss of fiber strength. Four substrates, five coatings, and two metal matrix materials were employed for a total of forty material combinations. The substrates were tungsten, niobium, NASA-Hough carbon, and Tyco sapphire. The diffusion-barrier coatings were aluminum oxide, yttrium oxide, titanium carbide, tungsten carbide with 14% cobalt addition, and zirconium carbide. The metal matrix materials were IN 600 nickel and Ti 6/4 titanium. Adhesion of the coatings to all substrates was good except for the NASA-Hough carbon, where flaking off of the oxide coatings in particular was observed.

  15. The influence of titanium and iron oxides on the coloring and friability of the blue fired aluminum oxide as an abrasive material

    OpenAIRE

    E. R. Passos; J. A. Rodrigues

    2016-01-01

    Abstract The quality of abrasive grains is crucial to increase the lifespan of roughing, polishing and cutting tools. The purpose of the work herein was to evaluate the variables of the blue fired aluminum oxide heat treatment process. This heat treatment process improves the physical properties of the brown fused aluminum oxide and results in a blue coloring, which uniquely identifies it within the abrasives industry. The work herein includes information beginning with the electro-fusion pro...

  16. Synthesis and structure analysis of aluminum doped zinc oxide powders

    Institute of Scientific and Technical Information of China (English)

    NIE DengPan; XUE Tao; ZHANG Yu; LI XiangJun

    2008-01-01

    Hexagonal Al-doped zinc oxide (ZnO) powders with a nominal composition of Zn1-xAlxO (0≤x≤0.028) were synthesized by the co-precipitation method. The contents of the Al element in the samples were measured by the inductively coupled plasma-optical emission spectroscopy (ICP-OES) technique. The structures of the Zn1-xAlxO (0≤x≤0.028) compounds calcined at 1000 and 1200℃ have been deter-mined using the Rietveld full-profile analysis method. Rietveld refinements of the diffraction data indi-cated that the addition of Al initially has a considerably positive effect on the decreasing of the lattice parameters a and c of Zn1-xAlxO, but the effect becomes very slight and even negative with the further increase of the Al content. The solid solubility limit of Al in ZnO (mole fraction y) is 2.21%, resulting in Zn0.978Al0.22O. It seems that when the Al content is excessive, Al prefers to form a ZnAl2O4 compound with ZnO, but not to incorporate into the ZnO lattice to occupy the Zn2+ cites. Two phases, [ZnO] (or Al-doped ZnO) and [ZnAl2O4], are obviously segregated in Zn1-xAlxO while the value of x is larger than 0.024. The UV-Vis absorption spectra show that the Al-doped ZnO exhibits a red-shift in the absorption edge without reduced transmission compared with pure ZnO, which also confirms that Al ions enter the ZnO lattice and form a Zn1-xAlxO solid solution.

  17. Synthesis and structure analysis of aluminum doped zinc oxide powders

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Hexagonal Al-doped zinc oxide (ZnO) powders with a nominal composition of Zn1-xAlxO (0≤x≤0.028) were synthesized by the co-precipitation method. The contents of the Al element in the samples were measured by the inductively coupled plasma-optical emission spectroscopy (ICP-OES) technique. The structures of the Zn1-xAlxO (0≤x≤0.028) compounds calcined at 1000 and 1200℃ have been deter- mined using the Rietveld full-profile analysis method. Rietveld refinements of the diffraction data indi- cated that the addition of Al initially has a considerably positive effect on the decreasing of the lattice parameters a and c of Zn1-xAlxO, but the effect becomes very slight and even negative with the further increase of the Al content. The solid solubility limit of Al in ZnO (mole fraction y) is 2.2l%, resulting in Zn0.978Al0.22O. It seems that when the Al content is excessive, Al prefers to form a ZnAl2O4 compound with ZnO, but not to incorporate into the ZnO lattice to occupy the Zn2+ cites. Two phases, [ZnO] (or Al-doped ZnO) and [ZnAl2O4], are obviously segregated in Zn1-xAlxO while the value of x is larger than 0.024. The UV-Vis absorption spectra show that the Al-doped ZnO exhibits a red-shift in the absorption edge without reduced transmission compared with pure ZnO, which also confirms that Al ions enter the ZnO lattice and form a Zn1-xAlxO solid solution.

  18. The influence of titanium and iron oxides on the coloring and friability of the blue fired aluminum oxide as an abrasive material

    Directory of Open Access Journals (Sweden)

    E. R. Passos

    2016-03-01

    Full Text Available Abstract The quality of abrasive grains is crucial to increase the lifespan of roughing, polishing and cutting tools. The purpose of the work herein was to evaluate the variables of the blue fired aluminum oxide heat treatment process. This heat treatment process improves the physical properties of the brown fused aluminum oxide and results in a blue coloring, which uniquely identifies it within the abrasives industry. The work herein includes information beginning with the electro-fusion process of bauxite (the manufacturing of the brown fused aluminum oxide to the Blue Fired process. It also compares the fracture resistance index between these materials. This index is the inverse of the friability. Besides the content of titanium and iron oxides, process variables such as time, temperature and atmospheric conditions are important to monitor in order to reach standard requirements. Experimental evidence measuring these parameters is presented in the article herein. The blue coloring of this aluminum oxide is explained by the optical phenomena of electron transition, and not by the formation of aluminum titanate, as some technical literature has stated. Furthermore, it was proved that the coloring of blue fired material should not be used exclusively as an indicator of the optimal abrasive characteristics of this class of aluminum oxide.

  19. Surface reaction mechanisms during ozone and oxygen plasma assisted atomic layer deposition of aluminum oxide.

    Science.gov (United States)

    Rai, Vikrant R; Vandalon, Vincent; Agarwal, Sumit

    2010-09-01

    We have elucidated the reaction mechanism and the role of the reactive intermediates in the atomic layer deposition (ALD) of aluminum oxide from trimethyl aluminum in conjunction with O(3) and an O(2) plasma. In situ attenuated total reflection Fourier transform infrared spectroscopy data show that both -OH groups and carbonates are formed on the surface during the oxidation cycle. These carbonates, once formed on the surface, are stable to prolonged O(3) exposure in the same cycle. However, in the case of plasma-assisted ALD, the carbonates decompose upon prolonged O(2) plasma exposure via a series reaction kinetics of the type, A (CH(3)) --> B (carbonates) --> C (Al(2)O(3)). The ratio of -OH groups to carbonates on the surface strongly depends on the oxidizing agent, and also the duration of the oxidation cycle in plasma-assisted ALD. However, in both O(3) and O(2) plasma cycles, carbonates are a small fraction of the total number of reactive sites compared to the hydroxyl groups.

  20. Study on wear behavior of plasma electrolytic oxidation coatings on aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    CUI Shihai; HAN Jianmin; LI Weijing; KANG Suk-Bong; LEE Jung-Moo

    2006-01-01

    Thick and hard ceramic coatings were fabricated on A356 aluminum alloy by using plasma electrolytic oxidation(PEO) technique.The microstructure and phase composition of the PEO coatings were examined by using SEM and XRD method.It is found that the PEO coatings are mainly composed of crystalline α-Al2O3 and mullite.The dry sliding wear test of PEO coatings were carried out on a ring-on-ring wear machine.Results shows that there is hardly no wear loss of polished PEO coatings while the wear rate of uncoated aluminum alloy is 4.3×10-5 mm3·(N·m)-1 at a speed of 0.52 m·s-1 and a load of 40 N.

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

    Science.gov (United States)

    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.

  2. Method of making highly porous, stable aluminum oxides doped with silicon

    Energy Technology Data Exchange (ETDEWEB)

    Khosravi-Mardkhe, Maryam; Woodfield, Brian F.; Bartholomew, Calvin H.; Huang, Baiyu

    2016-03-22

    The present invention relates to a method for making high surface area and large pore volume thermally stable silica-doped alumina (aluminum oxide) catalyst support and ceramic materials. The ability of the silica-alumina to withstand high temperatures in presence or absence of water and prevent sintering allows it to maintain good activity over a long period of time in catalytic reactions. The method of preparing such materials includes adding organic silicon reagents to an organic aluminum salt such as an alkoxide in a controlled quantity as a doping agent in a solid state, solvent deficient reaction followed by calcination. Alternatively, the organic silicon compound may be added after calcination of the alumina, followed by another calcination step. This method is inexpensive and simple. The alumina catalyst support material prepared by the subject method maintains high pore volumes, pore diameters and surface areas at very high temperatures and in the presence of steam.

  3. Sound Absorption Characteristics of Aluminum Foams Treated by Plasma Electrolytic Oxidation

    Directory of Open Access Journals (Sweden)

    Wei Jin

    2015-11-01

    Full Text Available Open-celled aluminum foams with different pore sizes were fabricated. A plasma electrolytic oxidation (PEO treatment was applied on the aluminum foams to create a layer of ceramic coating. The sound absorption coefficients of the foams were measured by an impedance tube and they were calculated by a transfer function method. The experimental results show that the sound absorption coefficient of the foam increases gradually with the decrease of pore size. Additionally, when the porosity of the foam increases, the sound absorption coefficient also increases. The PEO coating surface is rough and porous, which is beneficial for improvement in sound absorption. After PEO treatment, the maximum sound absorption of the foam is improved to some extent.

  4. Determining the Effect of Aluminum Oxide Nanoparticles on the Aggregation of Amyloid-Beta in Transgenic Caenorhabditis elegans

    Science.gov (United States)

    Patel, Suhag; Matticks, John; Howell, Carina

    2014-03-01

    The cause of Alzheimer's disease has been linked partially to genetic factors but the predicted environmental components have yet to be determined. In Alzheimer's, accumulation of amyloid-beta protein in the brain forms plaques resulting in neurodegeneration and loss of mental functions. It has been postulated that aluminum influences the aggregation of amyloid-beta. To test this hypothesis, transgenic Caenorhabditis elegans, CL2120, was used as a model organism to observe neurodegeneration in nematodes exposed to aluminum oxide nanoparticles. Behavioral testing, fluorescent staining, and fluorescence microscopy were used to test the effects of aggregation of amyloid-beta in the nervous systems of effected nematodes exposed to aluminum oxide nanoparticles. Energy-dispersive x-ray spectroscopy was used to quantify the total concentration of aluminum oxide that the worms were exposed to during the experiment. Exposure of transgenic and wild type worms to a concentration of 4 mg mL-1 aluminum oxide showed a decrease in the sinusoidal motion, as well as an infirmity of transgenic worms when compared to control worms. These results support the hypothesis that aluminum may play a role in neurodegeneration in C. elegans, and may influence and increase the progression of Alzheimer's disease. This work was supported by National Science Foundation grants DUE-1058829, DMR-0923047 DUE-0806660 and Lock Haven FPDC grants.

  5. Effect of environment on iodine oxidation state and reactivity with aluminum.

    Science.gov (United States)

    Smith, Dylan K; McCollum, Jena; Pantoya, Michelle L

    2016-04-28

    Iodine oxide is a highly reactive solid oxidizer and with its abundant generation of iodine gas during reaction, this oxidizer also shows great potential as a biocidal agent. A problem with using I2O5 in an energetic mixture is its highly variable reactive behavior. This study isolates the variable reactivity associated with I2O5 as a function of its chemical reaction in various environments. Specifically, aluminum fuel and iodine oxide powder are combined using a carrier fluid to aid intermixing. The carrier fluid is shown to significantly affect the oxidation state of iodine oxide, thereby affecting the reactivity of the mixture. Four carrier fluids were investigated ranging in polarity and water miscibility in increasing order from hexane accounts for the increase in reactivity seen in the mixtures processed in polar fluids. These results explain the chemical mechanisms underlying the variable reactivity of I2O5 that are a function of the oxide's highly reactive nature with its surrounding environment. These results will significantly impact the selection of carrier fluid in the synthesis approach for iodine containing reactive mixtures. PMID:27052472

  6. Polymer-templated mesoporous carbons synthesized in the presence of nickel nanoparticles, nickel oxide nanoparticles, and nickel nitrate

    Science.gov (United States)

    Choma, Jerzy; Jedynak, Katarzyna; Marszewski, Michal; Jaroniec, Mietek

    2012-02-01

    Mesoporous carbon composites, containing nickel and nickel oxide nanoparticles, were obtained by soft-templating method. Samples were synthesized under acidic conditions using resorcinol and formaldehyde as carbon precursors, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock co-polymer Lutrol F127 as a soft template and nickel and nickel oxide nanoparticles, and nickel nitrate as metal precursors. In addition, a one set of samples was obtained by impregnation of mesoporous carbons with a nickel nitrate solution followed by further annealing at 400 °C. Wide angle X-ray powder diffraction along with thermogravimetric analysis proved the presence of nickel nanoparticles in the final composites obtained using nickel and nickel oxide nanoparticles, and Ni(NO3)2 solution. Whereas, the impregnation of carbons with a nickel nitrate solution followed by annealing at 400 °C resulted in needle-like nickel oxide nanoparticles present inside the composites’ pores. Low-temperature (-196 °C) nitrogen physisorption, X-ray powder diffraction, and thermogravimetric analysis confirmed good adsorption and structural properties of the synthesized nickel-carbon composites, in particular, the samples possessed high surface areas (>600 m2/g), large total pore volumes (>0.50 cm3/g), and maxima of pore size distribution functions at circa 7 nm. It was found that the composites were partially graphitized during carbonization process at 850 °C. The samples are stable in an air environment below temperature of 500 °C. All these features make the synthesized nickel-carbon composites attractive materials for adsorption, catalysis, energy storage, and environmental applications.

  7. Study on phosphating treatment of aluminum alloy: role of yttrium oxide

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shenglin

    2009-01-01

    Zinc phosphate coatings formed on 6061-Al alloy, after dipping in phosphating solutions containing different amounts of Y2O3(yttrium oxide), were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and electrochemical measurements. Significant variations in the morphology and corrosion resistance afforded by zinc phosphate coating were especially observed as Y2O3 in phosphating solution varied from 0 to 40 mg/L. The addition of Y2O3 changed the initial potential of the interface between aluminum alloy substrate and phosphating solution and increased the number of nucleation sites. The phosphate coating thereby was less porous structure and covered the surface of aluminum alloy completely within short phosphating time. Phosphate coating was mainly composed of Zn3(PO4)2-4H2O (hopeite) and AIPO4(aluminum phosphate). Y2O3, as an additive of phosphatization, accelerated precipitation and refined the gain size of phosphate coating. The corrosion resistance of zinc phosphate coating in 3% NaCl solution was improved as shown by po-larization measurement. In the present research, the optimal amount of Y2O3 was 10-20 mg/L, and the optimal phosphating time was 600 s.

  8. Preparation of copper nano-wires by template synthesis method

    Institute of Scientific and Technical Information of China (English)

    郑国渠; 倪似愚; 郑华钧; 干学宏; 张九渊

    2004-01-01

    Highly ordered and porous anodic aluminum oxide templates were prepared. The ordered copper nanowires arrays were assembled in nano-holes of the template by alternating current electrodeposition at lower voltage.The morphologies of template and copper nano-wires arrays were characterized by means of field emission scanning electron microscope(FESEM) and the crystal structure of copper nano-wires was determined by means of X-ray diffraction. The results indicate that copper nano-wires hold the preferred crystalline orientation along (111), (200),(220) and (331) crystal faces during growth, and the growth of copper nano-wires in the nano-holes of the template is homogenous and continuous.

  9. Effect of environment on iodine oxidation state and reactivity with aluminum.

    Science.gov (United States)

    Smith, Dylan K; McCollum, Jena; Pantoya, Michelle L

    2016-04-28

    Iodine oxide is a highly reactive solid oxidizer and with its abundant generation of iodine gas during reaction, this oxidizer also shows great potential as a biocidal agent. A problem with using I2O5 in an energetic mixture is its highly variable reactive behavior. This study isolates the variable reactivity associated with I2O5 as a function of its chemical reaction in various environments. Specifically, aluminum fuel and iodine oxide powder are combined using a carrier fluid to aid intermixing. The carrier fluid is shown to significantly affect the oxidation state of iodine oxide, thereby affecting the reactivity of the mixture. Four carrier fluids were investigated ranging in polarity and water miscibility in increasing order from hexane X-ray photoelectric spectroscopy (XPS) and differential scanning calorimetry (DSC). Results are compared with thermal equilibrium simulations. Flame speeds increased with polarity of the fluid used to intermix the powder and ranged from 180 to 1202 m s(-1). The I2O5 processed in the polar fluids formed hydrated states of iodine oxide: HIO3 and HI3O8; and, the nonpolar and dry-mixed samples formed: I2O4 and I4O9. During combustion, the hydrated iodine oxides rapidly dehydrated from HIO3 to HI3O8 and from HI3O8 to I2O5. Both steps release 25% of their mass as vapor during combustion. Increased gas generation enhances convective energy transport and accounts for the increase in reactivity seen in the mixtures processed in polar fluids. These results explain the chemical mechanisms underlying the variable reactivity of I2O5 that are a function of the oxide's highly reactive nature with its surrounding environment. These results will significantly impact the selection of carrier fluid in the synthesis approach for iodine containing reactive mixtures.

  10. Coral reef-like polyanaline nanotubes prepared by a reactive template of manganese oxide for supercapacitor electrode

    Institute of Scientific and Technical Information of China (English)

    Ling Ren Wang; Fen Ran; Yong Tao Tan; Lei Zhao; Ling Bin Kong; Long Kang

    2011-01-01

    Coral reef-like PANI nanotubes composed of nanopaticles were successfully synthesized by a reactive template of manganese oxide. The structure was characterized by using SEM, TEM, and FT-IR, and the supercapacitive behaviors of these nanotubes were investigated with cyclic voltammetry (CV), and charge-discharge tests, respectively. A maximum specific capacitance of 533 F/g could be achieved in 1 mol/L aqueous H2SO4 with the potential range of -0.2 to 0.8 V (vs. the saturated calomel electrode) in a half-cell setup configuration for PANI electrode, suggesting its potential application in the electrode material for electrochemical capacitors.

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

    Science.gov (United States)

    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. PMID:21197062

  12. A study of the initial oxidation of evaporated thin films of aluminum by AES, ELS, and ESD

    Science.gov (United States)

    Bujor, M.; Larson, L. A.; Poppa, H.

    1982-01-01

    The room temperature, low pressure, oxidation of evaporated aluminum thin films has been studied by AES, ELS, and ESD. ESD was the most sensitive of the three methods to characterize a clean aluminum surface. Two oxidation stages were distinguished in the 0-3000 L oxygen exposure range. Between 0 and 50 L, the chemisorption of oxygen atoms was characterized by a fast decrease of the 67 eV AES Al peak and the 10 eV surface plasmon peak, and by a simultaneous increase of the oxygen AES and ESD signals. After 50 L, a change in slope in all AES and ESD signal variations was attributed to the slow growth of a thin layer of aluminum oxide, which after 3000 L was still only a few angstroms thick.

  13. Effects of rare earth oxide additives on the thermal behaviors of aluminum nitride ceramics

    Institute of Scientific and Technical Information of China (English)

    YAO Yijun; WANG Ling; LI Chuncheng; JIANG Xiaolong; QIU Tai

    2009-01-01

    The effects of Y_2O_3 and Er_2O_3 on the sintering behaviors, thermal properties and microstructure of AIN ceramics were investigated. The ex-perimental results show that the sintering temperature can be decreased; the relative density and thermal behavior can be improved by adding rare earth oxide in AIN ceramics. For AIN ceramics with 3 wt.% Er_2O_3 additive, the relative density is 98.8%, and the thermal conductivity reaches 106 W·m~(-1)·K~(-1). The microstructure research found that no obvious aluminum erbium oxide was found in AIN ceramics doped with 3 wt.% Er_2O_3, which favored the improvement of the thermal conductivity of AIN ceramics.

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

    Directory of Open Access Journals (Sweden)

    M. Morales-Masis

    2014-09-01

    Full Text Available 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 (H2-plasma post-deposition treatment improves the conductivity of amorphous aluminum-doped zinc tin oxide while retaining its low optical absorption. We found that the H2-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.

  15. A molecular beacon biosensor based on the nanostructured aluminum oxide surface.

    Science.gov (United States)

    Che, Xiangchen; He, Yuan; Yin, Haocheng; Que, Long

    2015-10-15

    A new class of molecular beacon biosensors based on the nanostructured aluminum oxide or anodic aluminum oxide (AAO) surface is reported. In this type of sensor, the AAO surface is used to enhance the fluorescent signals of the fluorophore-labeled hairpin DNA. When a target DNA with a complementary sequence to that of the hairpin DNA is applied on the sensor, the fluorophores are forced to move away from the AAO surface due to the hybridization between the hairpin DNA and the target DNA, resulting in the significant decrease of the fluorescent signals. The observed signal reduction is sufficient to achieve a demonstrated detection limit of 10nM, which could be further improved by optimizing the AAO surface. The control experiments have also demonstrated that the bioassay used in the experiments has excellent specificity and selectivity, indicating the great promise of this type of sensor for diagnostic applications. Since the arrayed AAO micropatterns can be fabricated on a single chip in a cost-effective manner, the arrayed sensors could provide an ideal technical platform for studying fundamental biological process and monitoring disease biomarkers.

  16. Effects of iron and aluminum oxides and clay content on penetration resistance of five Greek soils

    Directory of Open Access Journals (Sweden)

    Stefanos Stefanou

    2013-07-01

    Full Text Available The effect of amorphous and crystalline iron (Fe and aluminum (Al oxides and oxy-hydroxides as well as clay on soil penetration resistance of five Greek soils, as a function of soil water suction was studied for the whole range of soil moisture. The soils tested were of loamy texture and were collected from cultivated and non-cultivated areas of north and central Greece (Macedonia and Thessaly. The study aimed at understanding the role of the above mentioned soil components on penetration resistance. The findings showed that the increase of iron and aluminum oxides and oxy-hydroxides content resulted in an increase of soil penetration resistance and the relationships between them were significant. Crystalline iron forms found to have a more profound effect on penetration resistance as compared to amorphous iron forms. Finally, positive and significant relationships were also found between penetration resistance and clay content. However, it is not entirely clear which of the two soil components plays the most important role in penetration resistance changes in soils.

  17. An investigation of the electrical behavior of thermally-sprayed aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    Swindeman, C.J.; Seals, R.D.; White, R.L.; Murray, W.P.; Cooper, M.H.

    1996-09-01

    Electrical properties of plasma-sprayed aluminum oxide coatings were measured at temperatures up to 600 C. High purity (> 99.5 wt% pure Al{sub 2}O{sub 3}) alumina powders were plasma-sprayed on stainless steel substrates over a range of power levels, using two gun configurations designed to attain different spray velocities. Key electrical properties were measured to evaluate the resultant coatings as potential insulating materials for electrostatic chucks (ESCs) being developed for semiconductor manufacturing. Electrical resistivity of all coatings was measured under vacuum upon heating and cooling over a temperature range of 20 to 600 C. Dielectric constants were also measured under the same test conditions. X-ray diffraction was performed to examine phase formation in the coatings. Results show the important of powder composition and careful selection and control of spray conditions for optimizing electrical behavior in plasma-sprayed aluminum oxide, and point to the need for further studies to characterize the relationship between high temperature electrical properties, measured plasma-spray variables, and specific microstructural and compositional coating features.

  18. New roots to formation of nanostructures on glass surface through anodic oxidation of sputtered aluminum

    Directory of Open Access Journals (Sweden)

    Satoru Inoue, Song-Zhu Chu, Kenji Wada, Di Li and Hajime Haneda

    2003-01-01

    Full Text Available New processes for the preparation of nanostructure on glass surfaces have been developed through anodic oxidation of sputtered aluminum. Aluminum thin film sputtered on a tin doped indium oxide (ITO thin film on a glass surface was converted into alumina by anodic oxidation. The anodic alumina gave nanometer size pore array standing vertically on the glass surface. Kinds of acids used in the anodic oxidation changed the pore size drastically. The employment of phosphoric acid solution gave several tens nanometer size pores. Oxalic acid cases produced a few tens nanometer size pores and sulfuric acid solution provided a few nanometer size pores. The number of pores in a unit area could be changed with varying the applied voltage in the anodization and the pore sizes could be increased by phosphoric acid etching. The specimen consisting of a glass substrate with the alumina nanostructures on the surface could transmit UV and visible light. An etched specimen was dipped in a TiO2 sol solution, resulting in the impregnation of TiO2 sol into the pores of alumina layer. The TiO2 sol was heated at ~400 °C for 2 h, converting into anatase phase TiO2. The specimens possessing TiO2 film on the pore wall were transparent to the light in UV–Visible region. The electro deposition technique was applied to the introduction of Ni metal into pores, giving Ni nanorod array on the glass surface. The removal of the barrier layer alumina at the bottom of the pores was necessary to attain smooth electro deposition of Ni. The photo catalytic function of the specimens possessing TiO2 nanotube array was investigated in the decomposition of acetaldehyde gas under the irradiation of UV light, showing that the rate of the decomposition was quite large.

  19. Photoluminescence blue shift of indium phosphide nanowire networks with aluminum oxide coating

    Energy Technology Data Exchange (ETDEWEB)

    Fryauf, David M.; Zhang, Junce; Norris, Kate J.; Diaz Leon, Juan J.; Oye, Michael M.; Kobayashi, Nobuhiko P. [Nanostructured Energy Conversion Technology and Research (NECTAR), Advanced Studies Laboratories, University of California, Santa Cruz, CA (United States); Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, CA (United States); NASA Ames Research Center, Moffett Field, CA (United States); Wei, Min [Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, CA (United States); School of Micro-Electronics and Solid-Electronics, University of Electronic Science and Technology of China, Chengdu (China)

    2014-07-15

    This paper describes our finding that optical properties of semiconductor nanowires were modified by depositing a thin layer of metal oxide. Indium phosphide nanowires were grown by metal organic chemical vapor deposition on silicon substrates with gold catalyst resulting in three-dimensional nanowire networks, and optical properties were obtained from the collective nanowire networks. The networks were coated with an aluminum oxide thin film deposited by plasma-enhanced atomic layer deposition. We studied the dependence of the peak wavelength of photoluminescence spectra on the thickness of the oxide coatings. A continuous blue shift in photoluminescence spectra was observed when the thickness of the oxide coating was increased. The observed blue shift is attributed to the Burstein-Moss effect due to increased carrier concentration in the nanowire cores caused by repulsion from intrinsic negative fixed charges located at the inner oxide surface. Samples were further characterized by scanning electron microscopy, Raman spectroscopy, transmission electron microscopy, and selective area diffractometry to better understand the physical mechanisms for the blue shift. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Comparative Assessment of Antimicrobial Efficiency of Ionic Silver, Silver Monoxide, and Metallic Silver Incorporated onto an Aluminum Oxide Nanopowder Carrier

    OpenAIRE

    Agnieszka Maria Jastrzębska; Ewa Karwowska; Andrzej R. Olszyna; Antoni R. Kunicki

    2013-01-01

    The present paper provides comparative assessment of antimicrobial efficiency of ionic silver (Ag+), silver monoxide (Ag2O), and metallic silver (Ag) incorporated onto an aluminum oxide nanopowder carrier (Al2O3). The deposition of Ag+ ions, Ag2O nanoparticles, and Ag nanoparticles on an different phases of aluminum oxide nanopowder carrier was realized using consecutive stages of dry sol-gel method. The Al2O3-Ag+, Al2O3-Ag2O, and Al2O3-Ag nanopowders were widely characterized qualitatively a...

  1. Murine pulmonary responses after sub-chronic exposure to aluminum oxide-based nanowhiskers

    Directory of Open Access Journals (Sweden)

    Adamcakova-Dodd Andrea

    2012-06-01

    Full Text Available Abstract Background Aluminum oxide-based nanowhiskers (AO nanowhiskers have been used in manufacturing processes as catalyst supports, flame retardants, adsorbents, or in ceramic, metal and plastic composite materials. They are classified as high aspect ratio nanomaterials. Our aim was to assess in vivo toxicity of inhaled AO nanowhisker aerosols. Methods Primary dimensions of AO nanowhiskers specified by manufacturer were 2–4 nm x 2800 nm. The aluminum content found in this nanomaterial was 30% [mixed phase material containing Al(OH3 and AlOOH]. Male mice (C57Bl/6 J were exposed to AO nanowhiskers for 4 hrs/day, 5 days/wk for 2 or 4 wks in a dynamic whole body exposure chamber. The whiskers were aerosolized with an acoustical dry aerosol generator that included a grounded metal elutriator and a venturi aspirator to enhance deagglomeration. Average concentration of aerosol in the chamber was 3.3 ± 0.6 mg/m3 and the mobility diameter was 150 ± 1.6 nm. Both groups of mice (2 or 4 wks exposure were necropsied immediately after the last exposure. Aluminum content in the lung, heart, liver, and spleen was determined. Pulmonary toxicity assessment was performed by evaluation of bronchoalveolar lavage (BAL fluid (enumeration of total and differential cells, total protein, activity of lactate dehydrogenase [LDH] and cytokines, blood (total and differential cell counts, lung histopathology and pulmonary mechanics. Results Following exposure, mean Al content of lungs was 0.25, 8.10 and 15.37 μg/g lung (dry wt respectively for sham, 2 wk and 4 wk exposure groups. The number of total cells and macrophages in BAL fluid was 2-times higher in animals exposed for 2 wks and 6-times higher in mice exposed for 4 wks, compared to shams (p p  Conclusions Sub-chronic inhalation exposures to aluminum-oxide based nanowhiskers induced increased lung macrophages, but no inflammatory or toxic responses were observed.

  2. Effect of interfacial oxide thickness on the photocatalytic activity of magnetron-sputtered TiO2 coatings on aluminum substrate

    DEFF Research Database (Denmark)

    Daviðsdóttir, Svava; Petit, Jean-Pierre; Shabadi, Rajashekhara;

    2015-01-01

    measurements showed a maximum UV-light absorption by titanium dioxide occurring slightly prior to the energy of the maximum photocurrent. The photocurrent of titanium dioxide decreases with increasing thickness of the aluminum oxide interface layer. Aluminum oxide acts as an insulator; disfavoring the electron...

  3. Effect of interfacial oxide thickness on the photocatalytic activity of magnetron-sputtered TiO2coatings on aluminum substrate

    DEFF Research Database (Denmark)

    Daviðsdóttir, Svava; Petit, Jean-Pierre; Shabadi, Rajashekhara;

    2015-01-01

    measurements showed a maximum UV-light absorption by titanium dioxide occurring slightly prior to the energy of the maximum photocurrent. The photocurrent of titanium dioxide decreases with increasing thickness of the aluminum oxide interface layer. Aluminum oxide acts as an insulator; disfavoring the electron...

  4. Oxidation Behavior of In-Flight Molten Aluminum Droplets in the Twin-Wire Electric Arc Thermal Spray Process

    Energy Technology Data Exchange (ETDEWEB)

    Donna Post Guillen; Brian G. Williams

    2005-05-01

    This paper examines the in-flight oxidation of molten aluminum sprayed in air using the twin-wire electric arc (TWEA) thermal spray process. The oxidation reaction of aluminum in air is highly exothermic and is represented by a heat generation term in the energy balance. Aerodynamic shear at the droplet surface enhances the amount of in-flight oxidation by: (1) promoting entrainment and mixing of the surface oxides within the droplet, and (2) causing a continuous heat generation effect that increases droplet temperature over that of a droplet without internal circulation. This continual source of heat input keeps the droplets in a liquid state during flight. A linear rate law based on the Mott-Cabrera theory was used to estimate the growth of the surface oxide layer formed during droplet flight. The calculated oxide volume fraction of an average droplet at impact agrees well with the experimentally determined oxide content for a typical TWEA-sprayed aluminum coating, which ranges from 3.3 to 12.7%. An explanation is provided for the elevated, nearly constant surface temperature (~ 2000 oC) of the droplets during flight to the substrate and shows that the majority of oxide content in the coating is produced during flight, rather than after deposition.

  5. Integration of biaxally aligned conducting oxides with silicon using ion-beam assisted deposited MgO templates

    Energy Technology Data Exchange (ETDEWEB)

    Park, B. H. (Bae Ho); Groves, J. R. (James R.); DePaula, R. F. (Raymond Felix); Jia, Quanxi; Arendt, P. N. (Paul N.); Emmert, L. A. (Luke A.)

    2001-01-01

    Two conducting oxides, La{sub 0.5}Sr{sub 0.5}CoO{sub 3}(LSCO) and SrRuO{sub 3}, were deposited by pulsed laser ablation onto silicon substrates coated with biaxially textured MgO on an amorphous silicon nitride isolation layer. Comparison is made between templates using just 10 nm of ion-beam assisted deposited (IBAD) MgO and substrates with an additional 100 nm of homoepitaxial MgO. Both of these conducting oxide layers exhibited in-plane and out-of-plane texture, on the order of that obtained by the underlying MgO. The SrRuO{sub 3} was c-axis oriented on both substrates, but exhibited a slightly sharper out-of-plane texture when the homoepitaxial MgO layer was included. On the other hand, the LSCO showed only (100) orientation when deposited directly on the IBAD-MgO templates, whereas a significant (110) peak was observed for films on the homoepitaxial MgO. A simple calculation of the distribution of grain boundary angles, assuming a normal distribution of grains, is also presented.

  6. Fabrication of hybrid graphene oxide/polyelectrolyte capsules by means of layer-by-layer assembly on erythrocyte cell templates

    Directory of Open Access Journals (Sweden)

    Joseba Irigoyen

    2015-12-01

    Full Text Available A novel and facile method was developed to produce hybrid graphene oxide (GO–polyelectrolyte (PE capsules using erythrocyte cells as templates. The capsules are easily produced through the layer-by-layer technique using alternating polyelectrolyte layers and GO sheets. The amount of GO and therefore its coverage in the resulting capsules can be tuned by adjusting the concentration of the GO dispersion during the assembly. The capsules retain the approximate shape and size of the erythrocyte template after the latter is totally removed by oxidation with NaOCl in water. The PE/GO capsules maintain their integrity and can be placed or located on other surfaces such as in a device. When the capsules are dried in air, they collapse to form a film that is approximately twice the thickness of the capsule membrane. AFM images in the present study suggest a film thickness of approx. 30 nm for the capsules in the collapsed state implying a thickness of approx. 15 nm for the layers in the collapsed capsule membrane. The polyelectrolytes used in the present study were polyallylamine hydrochloride (PAH and polystyrenesulfonate sodium salt (PSS. Capsules where characterized by transmission electron microscopy (TEM, atomic force microscopy (AFM, dynamic light scattering (DLS and Raman microscopy, the constituent layers by zeta potential and GO by TEM, XRD, and Raman and FTIR spectroscopies.

  7. Preparation of Pt-mesoporous tungsten carbide/carbon composites via a soft-template method for electrochemical methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Chun’an, E-mail: science@zjut.edu.cn; Kang, Lingzhi; Shi, Meiqin; Lang, Xiaoling; Jiang, Yekun

    2014-03-05

    Highlights: • Mesoporous composite Pt-m(WC/C) is prepared by a soft template method. • The structure of phenolic gives a space limitation effect on the growth of WC. • Analysis of the effect of F127 on controlling the structure of composites. • Pt-m(WC/C) exhibits more than three times higher than Pt/C in catalytic activity. -- Abstract: This paper introduces a simple and reproducible chemical process for synthesis of Pt-mesoporous tungsten carbide/carbon composites composites Pt-m(WC/C) by means of a soft-template method. In this process, low-molecular-weight phenolic resol acted as the precursor both for carbon support and also the carbon resource of tungsten carbide. Tungsten hexachloride was used as a tungsten precursor along with different amount of triblock copolymer Pluronic F127 as pore-forming component. The best performance of Pt-m(WC/C) towards methanol oxidation is found when the mass ratios of WCl{sub 6}:F127 is 1:0.6. The composite presents an improved methanol oxidation performance evidenced by a negative shift in onset potential, and increase of peak current density, compared with commercial Pt/C. The difference is explained by the adding of appropriate amount of F127 which facilitates the construction of mesoporous matrix structure of WC/C.

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

    International Nuclear Information System (INIS)

    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 gm change, threshold voltage VT 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

  9. Role of aluminum doping on phase transformations in nanoporous titania anodic oxides

    Energy Technology Data Exchange (ETDEWEB)

    Bayata, Fatma [Istanbul Bilgi University, Department of Mechanical Engineering, 34060, Eyup, Istanbul (Turkey); Ürgen, Mustafa, E-mail: urgen@itu.edu.tr [Istanbul Technical University, Department of Metallurgical and Materials Engineering, 34469, Maslak, Istanbul (Turkey)

    2015-10-15

    The role of aluminium doping on anatase to rutile phase transformation of nanoporous titanium oxide films were investigated. For this purpose pure and aluminum doped metal films were deposited on alumina substrates by cathodic arc physical deposition. The nanoporous anodic oxides were prepared by porous anodizing of pure and aluminum doped titanium metallic films in an ethylene glycol + NH{sub 4}F based electrolyte. Nanoporous amorphous structures with 60–80 nm diameter and 2–4 μm length were formed on the surfaces of alumina substrates. The amorphous undoped and Al-doped TiO{sub 2} anodic oxides were heat-treated at different temperatures in the range of 280–720 °C for the investigation of their crystallization behavior. The combined effects of nanoporous structure and Al doping on crystallization behavior of titania were investigated using X-ray diffraction (XRD) and micro Raman analysis. The results indicated that both Al ions incorporated into the TiO{sub 2} structure and the nanoporous structure retarded the rutile formation. It was also revealed that presence or absence of metallic film underneath the nanopores has a major contribution to anatase-rutile transformation. - Highlights: • Al-doped TiO{sub 2} nanopores were grown on alumina substrates using anodization method. • The crystallization behavior of nanoporous Al-doped TiO{sub 2} were investigated. • Al doping into nanoporous TiO{sub 2} retarded the anatase-rutile transformation. • Nanostructuring has significant role in controlling rutile formation temperature. • The absence of the metallic film under the nanopores delayed the rutile formation.

  10. Oxidative stress in blood and testicle of rat following intraperitoneal administration of aluminum and indium.

    Science.gov (United States)

    Maghraoui, S; Clichici, Simona; Ayadi, A; Login, C; Moldovan, R; Daicoviciu, D; Decea, N; Mureşan, A; Tekaya, L

    2014-03-01

    Aluminum (Al) and indium (In) have embryotoxic, neurotoxic and genotoxic effects, oxidative stress being one of the possible mechanisms involved in their cytotoxicity. We have recently demonstrated that indium intraperitoneal (ip) administration induced histological disorganization of testicular tissue. In the present research we aimed at investigating the effect of Al and In ip administration on systemic and testicular oxidative stress status. Studies were performed on Wistar rats ip injected with Al, In or physiological solution for two weeks. Our results showed that In significantly decreased the absolute weight of testicles. Measurements of lactate dehydrogenase (LDH) and paraoxonase (PON) activities showed that In induced a significant augmentation in the first parameter but no changes were observed in the second. Both Al and In caused oxidative stress in testicles by increasing malondialdehyde (MDA) and protein carbonyls (PC) production. Concomitantly, thiol group (-SH) and glutathione (GSH) level were enhanced in the testicles. In the blood, while concentrations of MDA was not changed, those of GSH was significantly decreased in the Al and In groups. Our results indicated that Al and In cause oxidative stress both in blood and testicles but In has cytotoxic effect as well as negative impact on testicle weights. These findings could explain the testicular histological alterations previously described after In ip administration.

  11. Interactions of aluminum with biochars and oxidized biochars: implications for the biochar aging process.

    Science.gov (United States)

    Qian, Linbo; Chen, Baoliang

    2014-01-15

    Interactions of aluminum with primary and oxidized biochars were compared to understand the changes in the adsorption properties of aged biochars. The structural characteristics of rice straw-derived biochars, before and after oxidation by HNO3/H2SO4, were analyzed by element composition, FTIR, and XPS. The adsorption of Al to primary biochars was dominated by binding to inorganic components (such as silicon particles) and surface complexation of oxygen-containing functional groups via esterification reactions. Oxidization (aging) introduced carboxylic functional groups on biochar surfaces, which served as additional binding sites for Al(3+). At pH 2.5-3.5, the Al(3+) binding was significantly greater on oxidized biochars than primary biochars. After loading with Al, the -COOH groups anchored to biochar surfaces were transformed into COO(-) groups, and the negative surface charge diminished, which indicated that Al(3+) coordinated with COO(-). Biochar is suggested as a potential adsorbent for removing Al from acidic soils. PMID:24364719

  12. In-Line Sputtered Gallium and Aluminum Codoped Zinc Oxide Films for Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Shang-Chou Chang

    2014-01-01

    Full Text Available Gallium and aluminum codoped zinc oxide (GAZO films were deposited at different temperatures by in-line sputtering. Aluminum is thermally unstable compared to other elements in GAZO films. The grains of GAZO films increase with deposition temperature. Coalescence between grains was observed for GAZO films deposited at 250°C. The deposition temperature exhibits positive influence on crystallinity, and electrical and optical properties of GAZO films. The carrier concentration and mobility of GAZO films increase, while the electrical resistivity of GAZO films decreases with deposition temperature. The average optical transmittance of GAZO films rises with deposition temperature. In-line sputtering demonstrates a potential method with simplicity, mass production, and large-area deposition to produce GAZO films with good electrical and optical quality. The electrical resistivity of 4.3 × 10−4 Ω cm and the average optical transmittance in the visible range from 400 to 800 nm of 92% can be obtained for GAZO films deposited at 250°C. The hybrid organic solar cells (OSC were fabricated on GAZO-coated glass substrates. Blended poly(3-hexylthiophene (P3HT and [6,6]-phenyl C61 butyric acid methyl ester (PCBM were the photoactive materials in OSC. The power conversion efficiency of OSC is 0.65% for the OSC with the 250°C deposited GAZO electrode.

  13. Chemical Bath Deposition of Aluminum Oxide Buffer on Curved Surfaces for Growing Aligned Carbon Nanotube Arrays.

    Science.gov (United States)

    Wang, Haitao; Na, Chongzheng

    2015-07-01

    Direct growth of vertically aligned carbon nanotube (CNT) arrays on substrates requires the deposition of an aluminum oxide buffer (AOB) layer to prevent the diffusion and coalescence of catalyst nanoparticles. Although AOB layers can be readily created on flat substrates using a variety of physical and chemical methods, the preparation of AOB layers on substrates with highly curved surfaces remains challenging. Here, we report a new solution-based method for preparing uniform layers of AOB on highly curved surfaces by the chemical bath deposition of basic aluminum sulfate and annealing. We show that the thickness of AOB layer can be increased by extending the immersion time of a substrate in the chemical bath, following the classical Johnson-Mehl-Avrami-Kolmogorov crystallization kinetics. The increase of AOB thickness in turn leads to the increase of CNT length and the reduction of CNT curviness. Using this method, we have successfully synthesized dense aligned CNT arrays of micrometers in length on substrates with highly curved surfaces including glass fibers, stainless steel mesh, and porous ceramic foam. PMID:26053766

  14. Formation of unidirectional nanoporous structures in thickly anodized aluminum oxide layer

    Institute of Scientific and Technical Information of China (English)

    Hyun-Chae NA; Taek-Jin SUNG; Seok-Heon YOON; Seung-Kyoun HYUN; Mok-Soon KIM; Young-Gi LEE; Sang-Hyun SHIN; Seok-Moon CHOI; Sung YI

    2009-01-01

    A series of anodic aluminum oxide(AAO) was grown on the commercially pure 1050 aluminum sheet by controlling electrolyte temperature (2-15 ℃) and anodizing time (0.5-6 h), using a fixed applied current density of 3 A/dm2 in diluted sulfuric acid electrolyte. A crack-free thick AAO with the thickness of 105-120 ìm and containing unidirectional nano sized pores (average pore diameter of 5-7 nm) is successfully achieved in the specimens anodized for 2 h, irrespective of electrolyte temperature. When anodizing time reaches 6 h, very thick AAO with the thickness of 230-284 ìm is grown, and average diameter of unidirectional pores is in the range of 6-24 nm. The higher values in both the AAO thickness and pore diameter are attained for the specimens anodized at higher temperatures of 10-15 ℃. A crack is observed to exist in the AAO after anodizing up to 4 h and more. A higher fraction (more than 9%) of the crack is shown in the specimens anodized at higher temperatures of 10-15 ℃ for 6 h and a considerable amount of giant cracks are contained.

  15. High-Quality, Ultraconformal Aluminum-Doped Zinc Oxide Nanoplasmonic and Hyperbolic Metamaterials.

    Science.gov (United States)

    Riley, Conor T; Smalley, Joseph S T; Post, Kirk W; Basov, Dimitri N; Fainman, Yeshaiahu; Wang, Deli; Liu, Zhaowei; Sirbuly, Donald J

    2016-02-17

    Aluminum-doped zinc oxide (AZO) is a tunable low-loss plasmonic material capable of supporting dopant concentrations high enough to operate at telecommunication wavelengths. Due to its ultrahigh conformality and compatibility with semiconductor processing, atomic layer deposition (ALD) is a powerful tool for many plasmonic applications. However, despite many attempts, high-quality AZO with a plasma frequency below 1550 nm has not yet been realized by ALD. Here a simple procedure is devised to tune the optical constants of AZO and enable plasmonic activity at 1550 nm with low loss. The highly conformal nature of ALD is also exploited to coat silicon nanopillars to create localized surface plasmon resonances that are tunable by adjusting the aluminum concentration, thermal conditions, and the use of a ZnO buffer layer. The high-quality AZO is then used to make a layered AZO/ZnO structure that displays negative refraction in the telecommunication wavelength region due to hyperbolic dispersion. Finally, a novel synthetic scheme is demonstrated to create AZO embedded nanowires in ZnO, which also exhibits hyperbolic dispersion.

  16. Influence of the atmospheric species water, oxygen, nitrogen and carbon dioxide on the degradation of aluminum doped zinc oxide layers

    NARCIS (Netherlands)

    Theelen, M.; Dasgupta, S.; Vroon, Z.; Kniknie, B.; Barreau, N.; Berkum, J. van; Zeman, M.

    2014-01-01

    Aluminum doped zinc oxide (ZnO:Al) layers were exposed to the atmospheric gases carbon dioxide (CO2), oxygen (O2), nitrogen (N 2) and air as well as liquid H2O purged with these gases, in order to investigate the chemical degradation behavior of these layers. The samples were analyzed by electrical,

  17. Effect of intermetallic phases on the anodic oxidation and corrosion of 5A06 aluminum alloy

    Science.gov (United States)

    Li, Song-mei; Li, Ying-dong; Zhang, You; Liu, Jian-hua; Yu, Mei

    2015-02-01

    Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered intermetallic particles were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) after pretreatment. The anodic film was investigated by transmission electron microscopy (TEM), and its corrosion resistance was analyzed by electrochemical impedance spectroscopy (EIS) and Tafel polarization in NaCl solution. The results show that the size of Al-Fe-Mg-Mn particles gradually decreases with the iron content. During anodizing, these intermetallic particles are gradually dissolved, leading to the complex porosity in the anodic film beneath the particles. After anodizing, the residual particles are mainly silicon-containing phases, which are embedded in the anodic film. Electrochemical measurements indicate that the porous anodic film layer is easily penetrated, and the barrier plays a dominant role in the overall protection. Meanwhile, self-healing behavior is observed during the long immersion time.

  18. Synthesis and properties of iridescent Zn-containing anodic aluminum oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Xiaoxuan; Sun, Huiyuan, E-mail: huiyuansun@126.com; Liu, Lihu; Hou, Xue; Liu, Huiyuan

    2015-07-01

    A simple method of fabricating Zn-containing anodic aluminum oxide films for multifunctional anticounterfeit technology is reported. The resulting membranes were characterized with UV–vis illumination studies, natural light illumination color experiments, and electron microscopy analysis. Deposition of Zn in the nanopore region can enhance the color saturation of the thin alumina film with different colors dramatically. Both the anodization time and etching time have great influence on the structural color. The mechanisms for the emergence of this phenomenon are discussed and theoretical analysis further demonstrates the experimental results. - Highlights: • Iridescent PAA@Zn nanocomposite films were successfully fabricated. • A simple organics-assisted method is applied to making a series of fancy and multicolor patterns. • The color varies with the angle of incidence of the light used to view the film as is expected with Bragg–Snell formula. • Such colored films could be used in multifunctional anti-counterfeiting applications.

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

    Science.gov (United States)

    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.

  20. Effect of magnesium in aluminum alloys on characteristics of microarc oxidation coatings

    Institute of Scientific and Technical Information of China (English)

    LIU Yao-hui; LI Song; YU Si-rong; ZHU Xian-yong; XU Bai-ming

    2006-01-01

    Microarc oxidation(MAO) coatings were prepared on the surface of aluminum alloys with different contents of magnesium. The morphologies and surface roughness of the coatings were characterized by Confocal laser scanning microscopy(CLSM). Phase and chemical composition of the MAO coatings were analyzed by X-ray diffractometry(XRD) and X-ray photoelectron spectroscopy(XPS). The experimental results show that the coatings formed on different substrates have two-layer morphologies and are mainly composed of Al2O3 and Al-Si-O phases. In addition, the content of Al2O3 increases with increasing the content of magnesium. XPS results prove that magnesium from substrate indeed participates in the MAO process and is incorporated into the coating in the form of MgO. The coating formed on Al-3Mg substrate has the smallest mass loss and the lowest friction coefficient of 0.17-0.19.

  1. Taguchi Optimization for Combustion Synthesis of Aluminum Oxide Nano-particles

    Institute of Scientific and Technical Information of China (English)

    EDRISSI Mohammad; NOROUZBEIGI Reza

    2008-01-01

    Nano-structured aluminum oxide powders were prepared by a combustion synthesis method utilizing serine as a new fuel. The product was sonicated to obtain nano powders. A Taguchi L-4 statistical design of combustion syn- thesis was utilized to optimize the production of γ-alumina powder. The product was characterized by XRD, BET, SEM, EDX and LLS. Nano crystalline γ-alumina with crystal sizes between 4.26 and 5.47 nm and α-Al2O3 powders with crystal sizes 24.51 and 28.62 nm were obtained by the combustion synthesis. The specific surface area was measured by a BET method to be 75.21 m2/g. The average particle size after sonication of product, observed by LLS, was 79.32 nm.

  2. Photoluminescence and Raman studies in swift heavy ion irradiated polycrystalline aluminum oxide

    Indian Academy of Sciences (India)

    K R Nagabhushana; B N Lakshminarasappa; Fouran Singh

    2009-10-01

    Polycrystalline aluminum oxide is synthesized by combustion technique and XRD studies of the sample revealed the -phase. The synthesized sample is irradiated with 120 MeV swift Au9+ ions for the fluence in the range from 1 × 1011 to 1 × 1013 ions cm-2. A broad photoluminescence (PL) emission with peak at ∼447 nm and two sharp emissions with peak at ∼ 679 and ∼ 695 nm are observed in pristine when sample was excited with 326 nm. However, in the irradiated samples the PL intensity at ∼ 447, 679 and 695 nm decreases with increase in ion fluence. The -Al2O3 gives rise to seven Raman modes with Raman intensity with peaks at ∼ 253, 396, 417, 546, 630, 842, 867 cm-1 observed in pristine. The intensity of these modes decreases with increase in ion fluence. However, the Raman modes observed at lower fluences are found to disappear at higher fluence.

  3. Microstructures and Composition of Ceramic Coatings on Aluminum Produced by Micro-Arc Oxidation

    Institute of Scientific and Technical Information of China (English)

    SHEN De-jiu; WANG Yu-lin; GU Wei-chao; XING Guang-zhong

    2004-01-01

    Microstructures and phase composition of the ceramic coatings formed on pure aluminum by heteropolar pulsed current ceramic synthesizing system for different periods were investigated by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). Results show that the amount of the discharge channels in the ceramic coating sminish while the aperture largen in the micro-arc oxidation process, and the surface of the ceramic coatingmelted and solidified in the process.XRD studies of ceramic coatings deposited for different time show that these coatings consist mainly of α-Al2 O3, γ-Al2 O3 , θ-Al2 O3 and a little amorphous phase, and phase composition of compact and porous ceramic coatings don' t have much difference but have a little change of the content of α-Al2 O3 and amorphous phase.

  4. Covalent functionalization of graphene oxide with polyglycerol and their use as templates for anchoring magnetic nanoparticles

    NARCIS (Netherlands)

    Pham, Tuan Anh; Kumar, Nanjundan Ashok; Jeong, Yeon Tae

    2010-01-01

    An efficient strategy for the preparation of water-dispersible hybrid material containing graphene oxide and polyglycerol for the first time is demonstrated. Pristine graphite was firstly oxidized to obtain graphene oxide with hydroxyl functional groups. Then, the covalent grafting of polyglycerol o

  5. Contribution of Iron and Aluminum Oxides to Electrokinetic Characteristics of Variable Charge Soils in Relation to Surface Charge

    Institute of Scientific and Technical Information of China (English)

    ZHANGHONG; ZHANGXIAO-NIAN

    1992-01-01

    The contribution of iron and aluminum oxides to electrokinetic characteristics of variable charge soils was studied through determination of electrophoretic mobilities of the red soils treated with either removal of iron oxides or coating of aluminum oxides,and of those deferrated under natural conditions.After removal of the iron oxides,zeta potentials of the latosol and the red earth decreased obviously with a shift of IEP to a lower pH,from 6.4 to 5.3 and 4.1 to 2.4 for the former and the latter,respectively,and the electrokinetic change for the latosol was greater than for the red earth.Zeta potentials of the kaolinite sample increased markedly after coated with iron oxides.The striking effect of iron oxides on electrokinetix properties of the soils was also demonstrated by the electrokinetic differences between the samples from the red and white zones of a plinthitic horizon formed naturally,and between the samples from the gley and bottom horizons of a paddy soil derived from a red earth.The coatings of aluminum oxides on the latosol and the yellow earth made their zeta potentials rise pronouncedly and their IEFs move toward higher pHs,from 6.2 to 6.8 and 4.3 to 5.3 for the former and the latter,respectively.The samples with different particle sizes also exhibited some electrokinetic variation.The experiment showed that the effects of iron and aluminum oxides were closely related to the pH and type of the soils.

  6. Copper-aluminum oxide catalysts for total oxidation of toluene synthesized by thermal decomposition of co-precipitated precursors

    Energy Technology Data Exchange (ETDEWEB)

    Białas, Anna [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków (Poland); Kuśtrowski, Piotr, E-mail: kustrows@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków (Poland); Dudek, Barbara; Piwowarska, Zofia; Wach, Anna [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków (Poland); Michalik, Marek [Institute of Geological Sciences, Jagiellonian University, Oleandry 2a, 30-063 Kraków (Poland); Kozak, Marek [Division of Petroleum Processing, Oil and Gas Institute, Łukasiewicza 1, 31-429 Kraków (Poland)

    2014-08-20

    Highlights: • Cu–Al oxides obtained by coprecipitation are active catalysts in toluene combustion. • Advantage of the catalyst is low copper content and alkali-free precipitating agent. • The stable oxide form built of CuO and CuAl{sub 2}O{sub 4} is attained at 900 °C. • The optimum atomic Cu:Al ratio, ensuring maximum toluene conversion, is about 0.6. • The most active sample contains small CuO crystallites dispersed on the surface. - Abstract: Copper–aluminum containing precursors with various Cu/Al molar ratios (from 0.32–1.28) were prepared by co-precipitation in the presence of ammonium carbonate. The thermal stability of the obtained materials was investigated by thermal analysis, which revealed three crucial decomposition steps, finally resulting in the formation of mixed Cu–Al oxides. The changes in structure and texture of the samples at each decomposition step were examined by X-ray diffraction (XRD), diffuse reflectance UV–vis spectroscopy (UV–vis-DRS) and low temperature sorption of nitrogen. It was found that the entire removal of structural carbonates requires a calcination temperature as high as 900 °C. The samples after thermal treatment at this temperature varied in the phase composition of the bulk (determined by XRD) as well as of the surface (determined by X-ray photoelectron spectroscopy). All samples contained the CuAl{sub 2}O{sub 4} phase. Furthermore, an increase in Cu content led to the appearance of an increasing amount of CuO. Copper oxide in the form of relatively small crystallites turned out to be the catalytically active phase in the total oxidation of toluene.

  7. An anode with aluminum doped on zinc oxide thin films for organic light emitting devices

    International Nuclear Information System (INIS)

    Doped zinc oxides are attractive alternative materials as transparent conducting electrode because they are nontoxic and inexpensive compared with indium tin oxide (ITO). Transparent conducting aluminum-doped zinc oxide (AZO) thin films have been deposited on glass substrates by DC reactive magnetron sputtering method. Films were deposited at a substrate temperature of 150-bar oC in 0.03 Pa of oxygen pressure. The electrical and optical properties of the film with the Al-doping amount of 2 wt% in the target were investigated. For the 300-nm thick AZO film deposited using a ZnO target with an Al content of 2 wt%, the lowest electrical resistivity was 4x10-4Ωcm and the average transmission in the visible range 400-700 nm was more than 90%. The AZO film was used as an anode contact to fabricate organic light-emitting diodes. The device performance was measured and the current efficiency of 2.9 cd/A was measured at a current density of 100 mA/cm2

  8. Oxide and proton conductivity in aluminum-doped tricalcium oxy-silicate

    Energy Technology Data Exchange (ETDEWEB)

    Porras-Vazquez, J.M.; De la Torre, A.G.; Losilla, E.R.; Aranda, M.A.G. [Dept. Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, Campus Teatinos, 29071-Malaga (Spain)

    2007-06-15

    Aluminum doping in tricalcium silicate, Ca{sub 3}(SiO{sub 4})O, has been studied by high-resolution laboratory X-ray powder diffraction and the Rietveld method. Two nominal series have been designed and studied. Oxygen-fixed Ca{sub 3-x/2}Al{sub x/2}(Si{sub 1-x/2}Al{sub x/2}O{sub 4})O series has been prepared as single-phase up to x = 0.03. However, oxygen-variable Ca{sub 3}(Si{sub 1-x}Al{sub x}O{sub 4})O{sub 1-x/2}{open_square}{sub x/2} series has not been stabilized for any composition. The samples show oxide anion conductivity with a small p-type electronic contribution under oxidizing conditions. Typical total conductivities for these solids are 10{sup -} {sup 5}-10{sup -} {sup 4}S cm{sup -} {sup 1} at 1100 K. The oxide ion transference numbers are very high, {proportional_to} 0.98, under reducing conditions, i.e. dry 5%H{sub 2}-N{sub 2}/air gradient. The oxide ion transference numbers are slightly lower, {proportional_to} 0.91 under oxidizing conditions, i.e. dry O{sub 2}/air gradient. These compounds display a very important proton contribution to the overall conductivities under humidified atmospheres. The proton transference number ranges between 0.72 and 0.55 at 873 and 1023 K, respectively. (author)

  9. Formation of bismuth oxide nanowires by simultaneous templating and electrochemical adhesion of DNA on Si/SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hale, Michael G. [School of Chemistry, Newcastle University, Newcastle upon Tyne, NE1 7RU (United Kingdom); Little, Ross; Salem, Mohamed Ali [School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne, NE1 7RU (United Kingdom); Hedley, Joseph H.; Horrocks, Benjamin R. [School of Chemistry, Newcastle University, Newcastle upon Tyne, NE1 7RU (United Kingdom); Siller, Lidija, E-mail: Lidija.Siller@ncl.ac.uk [School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne, NE1 7RU (United Kingdom)

    2012-10-01

    Deoxyribonucleic acid (DNA)-templated growth of Bi/Bi{sub 2}O{sub 3} nanowires attached to the Si surface was obtained by electrochemical reduction of Bi(III) at an n-type Si electrode in aqueous Bi(NO{sub 3}){sub 3}/HNO{sub 3} at pH 2.5 with calf thymus DNA. The nanowires had a mean diameter of 5 nm and a range of lengths from 1.4 {mu}m to 6.1 {mu}m. The composition and structure of the wires were determined by atomic force microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray photoemission spectroscopy. The dominant component of the material is Bi{sub 2}O{sub 3} owing to the rapid re-oxidation of nanoscale Bi in the presence of air and water. Our method has the potential to construct complex architectures of Bi/Bi{sub 2}O{sub 3} nanostrucures on high quality Si substrates. - Highlights: Black-Right-Pointing-Pointer We have developed an electrochemical method to grow Bi/Bi{sub 2}O{sub 3} nanowires on silicon. Black-Right-Pointing-Pointer Bi/Bi{sub 2}O{sub 3} nanowires are templated by deoxyribonucleic acid molecules. Black-Right-Pointing-Pointer The procedure also adheres the nanowires to the electrode for characterization.

  10. Synthesis of biomimetic cerium oxide by bean sprouts bio-template and its photocatalytic performance

    Institute of Scientific and Technical Information of China (English)

    周梦凯; 张凯; 陈丰; 陈志刚

    2016-01-01

    Biomimetic nano CeO2 materials were prepared by using bean sprouts as bio-template through impregnation and thermal decomposition. For characterization of structure, X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectra (UV-Vis/DRS) nitrogen adsorp-tion-desorption measurements and Labsolar H2 system were adopted. The results demonstrated that the samples prepared at 550 ºC not only completely removed the original bio-template, but also retained the morphology and microstructure of bean sprouts. Then the biomorphic structure of fluorite structure CeO2 material was obtained. Micro-pores with a diameter of about 2–3 nm were distributed among the particles, which provided more favorable channel for the photocatalytic reaction. Biomimetic CeO2 materials exhibited clear red shift (50 nm) compared with powder CeO2, which could be excited by visible irradiation. Biomimetic CeO2 materials dis-played the superior photocatalytic activity for the hydrogen production by water splitting under the sunlight irradiation, the hydrogen yield could reach 400μmol/g catalyst after 6 h.

  11. Functionalizing Aluminum Oxide by Ag Dendrite Deposition at the Anode during Simultaneous Electrochemical Oxidation of Al.

    Science.gov (United States)

    Rafailović, Lidija D; Gammer, Christoph; Rentenberger, Christian; Trišović, Tomislav; Kleber, Christoph; Karnthaler, Hans Peter

    2015-11-01

    A novel synthesis strategy is presented for depositing metallic Ag at the anode during simultaneous electrochemical oxidation of Al. This unexpected result is achieved based on galvanic coupling. Metallic dendritic nanostructures well-anchored in a high surface area supporting matrix are envisioned to open up a new avenue of applications. PMID:26398487

  12. On-substrate fabrication of porous Al2O3 templates with tunable pore diameters and interpore distances

    Science.gov (United States)

    Berger, Nele; Habouti, Salah; Rubahn, Horst-Günter; Es-Souni, Mohammed

    2016-03-01

    This work is focused on the on-substrate fabrication of porous aluminum oxide templates by anodization of a thin aluminum film deposited directly on the substrate using different concentrations of oxalic acid. These on-substrate templates are used for fabricating supported, free-standing nanorod (NR)-arrays by electrochemical deposition of Pt followed by the removal of the template. The interpore distance of the templates is tuned by varying the concentration of the electrolyte used for anodization and the applied voltage. The diameter of the pores (and thus the NRs of the resulting array) and wall thickness are influenced by modifying the pore opening time during immersion the sample in H3PO4.

  13. Template-engaged synthesis of hollow porous platinum-palladium alloy nanospheres for efficient methanol electro-oxidation

    Science.gov (United States)

    Qiu, Xiaoyu; Dai, Yuxuan; Zhu, Xiaoshu; Zhang, Hanyue; Wu, Ping; Tang, Yawen; Wei, Shaohua

    2016-01-01

    Hollow porous structures of Pt-Pd bimetallic alloy possess unique compositional and structural superiorities for catalytic and electrocatalytic applications, and are thus anticipated to manifest novel properties and/or enhanced performance compared with their monometallic counterparts. Herein, a general electrostatic-attraction-directed layer-by-layer assembly approach has been developed for the construction of a novel type of hollow porous Pt-Pd alloy nanospheres (Pt-Pd HPNSs) using SiO2 nanospheres as templates. Moreover, the Pt-Pd HPNSs with controllable shell thickness are prepared and their comparative electrocatalytic performances toward methanol oxidation reaction (MOR) are investigated. It's found that optimized Pt-Pd HPNSs manifests markedly enhanced catalytic activity and durability in comparison with both commercial Pt black and Pd black catalysts.

  14. Graphene Oxide Templated Growth and Superior Lithium Storage Performance of Novel Hierarchical Co2V2O7 Nanosheets.

    Science.gov (United States)

    Luo, Yanzhu; Xu, Xu; Zhang, Yuxiang; Chen, Chih-Yen; Zhou, Liang; Yan, Mengyu; Wei, Qiulong; Tian, Xiaocong; Mai, Liqiang

    2016-02-01

    Hierarchical Co2V2O7 nanosheets consisted of interconnected nanoparticles are synthesized by a facile method using graphene oxide as the template. The electrochemical reaction mechanism of the Co2V2O7 nanosheets is thoroughly investigated by in situ XRD and ex situ TEM. The initial Co2V2O7 transforms into CoO nanoparticles and vanadium oxides in the first cycle, and the following reversible conversion reaction mainly occurs between CoO and Co and lithiation/delithiation of the vanadium oxides. The Co2V2O7 nanosheet displays a high reversible capacity (962 mAh/g at 0.5 A/g) and remarkable high rate capability. When cycled at 5.0 A/g, a reversible capacity of 441 mAh/g can be retained after 900 cycles. The stable high capacity and excellent rate capability make the hierarchical Co2V2O7 nanosheets a promising anode material for lithium-ion batteries.

  15. Interface modification of organic photovoltaics by combining molybdenum oxide (MoO{sub x}) and molecular template layer

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Haichao [Institute of Super-microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Hunan Key Laboratory for Super-microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Yang, Junliang, E-mail: junliang.yang@csu.edu.cn [Institute of Super-microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Hunan Key Laboratory for Super-microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Fu, Lin; Xiong, Jian; Yang, Bingchu; Ouyang, Jun; Zhou, Conghua; Huang, Han [Institute of Super-microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Hunan Key Laboratory for Super-microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Gao, Yongli [Institute of Super-microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Hunan Key Laboratory for Super-microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States)

    2015-01-01

    We report discrete heterojunction small molecular organic photovoltaics (OPVs) with enhanced performance by modifying the interface using molybdenum oxide (MoO{sub x}) and molecular template layer perylene-3,4,9,10-tetracarboxylic-3,4,9,10-dianhydride (PTCDA). A large increase in open-circuit voltage was obtained in copper phthalocyanine/fullerene, i.e., CuPc/C{sub 60} and CuPc/PCBM, discrete planar heterojunction photovoltaics with an insertion of 5 nm MoO{sub x} hole transport layer at the interface between the anode electrode and the CuPc donor layer. It results from the band bending at the interface and the pinning of the highest occupied molecular orbital level of CuPc to the Fermi level of MoO{sub x} due to the defect states (oxygen vacancies) in MoO{sub x} thin films. Moreover, the short-circuit current showed an efficient improvement by inserting a 1 nm PTCDA layer at the interface between the MoO{sub x} layer and the CuPc layer. The PTCDA layer induces the growth of CuPc thin film with lying-down molecular arrangement, supporting the charge transports along the vertical direction. The power conversion efficiencies of CuPc/C{sub 60} and CuPc/PCBM discrete planar heterojunction photovoltaic devices were improved from about 0.80% to 1.50% with inserting both MoO{sub x} and PTCDA layers. The results suggest that the performance of organic discrete planar heterojunction photovoltaics could be optimized by interface modification with combining hole transport layer and molecular template layer, which are potentially suitable for other highly efficient OPVs, such as small molecular tandem OPVs. - Highlights: • Organic small molecule photovoltaics were fabricated by interface modification. • An inserted molybdenum oxide layer largely enhances open-circuit voltage. • An inserted molecular template layer dramatically improves short-circuit current. • The power conversion efficiencies are almost doubled with interface modification.

  16. Behavior of aluminum oxide, intermetallics and voids in Cu-Al wire bonds

    Energy Technology Data Exchange (ETDEWEB)

    Xu, H., E-mail: HXu14@bama.ua.edu [Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States); Liu, C.; Silberschmidt, V.V. [Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough LE11 3TU (United Kingdom); Pramana, S.S. [School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); White, T.J. [School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Centre for Advanced Microscopy, Australian National University, Canberra, ACT 2601 (Australia); Chen, Z. [School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Acoff, V.L. [Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States)

    2011-08-15

    Nanoscale interfacial evolution in Cu-Al wire bonds during isothermal annealing from 175 deg. C to 250 deg. C was investigated by high resolution transmission electron microscopy (HRTEM). The native aluminum oxide film ({approx}5 nm thick) of the Al pad migrates towards the Cu ball during annealing. The formation of intermetallic compounds (IMC) is controlled by Cu diffusion, where the kinetics obey a parabolic growth law until complete consumption of the Al pad. The activation energies to initiate crystallization of CuAl{sub 2} and Cu{sub 9}Al{sub 4} are 60.66 kJ mol{sup -1} and 75.61 kJ mol{sup -1}, respectively. During IMC development, Cu{sub 9}Al{sub 4} emerges as a second layer and grows together with the initial CuAl{sub 2}. When Al is completely consumed, CuAl{sub 2} transforms to Cu{sub 9}Al{sub 4}, which is the terminal product. Unlike the excessive void growth in Au-Al bonds, only a few voids nucleate in Cu-Al bonds after long-term annealing at high temperatures (e.g., 250 {sup o}C for 25 h), and their diameters are usually in the range of tens of nanometers. This is due to the lower oxidation rate and volumetric shrinkage of Cu-Al IMC compared with Au-Al IMC.

  17. Aluminum-induced oxidative stress and neurotoxicity in grass carp (Cyprinidae--Ctenopharingodon idella).

    Science.gov (United States)

    Fernández-Dávila, María Lourdes; Razo-Estrada, Amparo Celene; García-Medina, Sandra; Gómez-Oliván, Leobardo Manuel; Piñón-López, Manuel Jesús; Ibarra, Rocio Guzmán; Galar-Martínez, Marcela

    2012-02-01

    Aluminum is used in a large number of anthropogenic processes, leading to aquatic ecosystems pollution. Diverse studies show that in mammals this metal may produce oxidative stress, is neurotoxic, and is involved in the development of neurodegenerative disorders, such as Alzhaimer's and Parkinson's diseases. Nevertheless, there are only few studies with respect to Al-induced neurotoxicity on aquatic fauna, particularly on fishes of economical interest, such as the grass carp (Ctenopharingodon idella). This study evaluates Al-induced toxicity on the grass carp C. idella. Specimens were exposed to the maximum concentration allowed in order to protect aquatic life (0.1 mg L⁻¹), for 12, 24, 48, 72 and 96 h. After the exposure time, lipid peroxidation degree, superoxide dismutase and catalase activity, as well as dopamine, adrenaline and noradrenaline levels were evaluated. Al concentration in organisms and water was also measured, in order to determine the bioconcentration factor. Results show that Al bioconcentrates in grass carp inducing oxidative stress (increment of 300 and 455 percent on lipid peroxidation degree and SOD activity, and decrement of 49 percent on CAT activity) and neurotoxicity (increment of 55 and 155 percent on dopamine and adrenaline levels and decrement of 93 percent on noradrenaline level). PMID:21993346

  18. Impact of water corrosion on nanoscale conductance on aluminum doped zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong-Hun; Lee, Hyunsoo; Choi, Sunghyun [Graduate School of EEWS (WCU) and Nanocentury KI, KAIST, Daejeon, 305-701 (Korea, Republic of); Center for Nanomaterials and Chemical Reactions, Institute for Basic Science, Daejeon, 305-701 (Korea, Republic of); Bae, Kyoung Hwan [The Thin Film Coating Team, KCC Corporation, Marbook Dong 83, Ki-Heung Gu, Yong-In City, 459-708 (Korea, Republic of); Park, Jeong Young, E-mail: jeongypark@kaist.ac.kr [Graduate School of EEWS (WCU) and Nanocentury KI, KAIST, Daejeon, 305-701 (Korea, Republic of)

    2013-11-29

    One major cause of failure in solar cell modules is associated with the degradation of conductive layers by the ingress of water. In this study, the corrosive interactions between water and transparent conducting oxides, including aluminum-doped ZnO (AZO) and indium tin oxide (ITO), were studied. The AZO layer exhibited ∼ 90% increase in sheet resistance from 17.5 to 33 ohm/square after an accelerated moisture test where the samples were stored at 80 °C and 100% humidity, while the conductivity of the ITO layer remained essentially unchanged. In order to elucidate the water-induced degradation mechanism of AZO, the structure and composition were characterized with conductive atomic force microscopy, energy dispersive spectrometry (EDS), and X-ray photoelectron spectroscopy (XPS) before and after the moisture test. It was found that the grain boundary of AZO exhibits a higher local conductance compared to that in the middle of the grain. A decrease in local conductance at the grain boundary after the moisture test was observed, which is attributed to depletion of the Zn, based on XPS and EDS analyses. - Highlights: • The moisture treatment lowers the local conductance of Al-doped ZnO (AZO). • Conductive atomic force microscopy shows the nanoelectronic properties of AZO. • Locally conductive areas are distributed along the grain boundaries. • The ratio of Zn to O along the grain boundaries was higher than that inside the grain.

  19. Silicon effects on formation of EPO oxide coatings on aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, L. [Department of Mechanical, Automotive and Materials Engineering, University of Windsor, Windsor, ON, N9B 3P4 (Canada); Nie, X. [Department of Mechanical, Automotive and Materials Engineering, University of Windsor, Windsor, ON, N9B 3P4 (Canada)]. E-mail: xnie@uwindsor.ca

    2006-01-03

    Electrolytic plasma processes (EPP) can be used for cleaning, metal-coating, carburizing, nitriding, and oxidizing. Electrolytic plasma oxidizing (EPO) is an advanced technique to deposit thick and hard ceramic coatings on a number of aluminum alloys. However, the EPO treatment on Al-Si alloys with a high Si content has rarely been reported. In this research, an investigation was conducted to clarify the effects of silicon contents on the EPO coating formation, morphology, and composition. Cast hypereutectic 390 alloys ({approx} 17% Si) and hypoeutectic 319 alloys ({approx} 7% Si) were chosen as substrates. The coating morphology, composition, and microstructure of the EPO coatings on those substrates were investigated using scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD). A stylus roughness tester was used for surface roughness measurement. It was found that the EPO process had four stages where each stage was corresponding to various coating surface morphology, composition, and phase structures, characterised by different coating growth mechanisms.

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

    Science.gov (United States)

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

    2015-09-01

    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.

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Wing, Waylin J.; Sadeghi, Seyed M., E-mail: seyed.sadeghi@uah.edu; Gutha, Rithvik R.; Campbell, Quinn [Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Mao, Chuanbin [Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma 73019 (United States)

    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.

  3. Interactive effect of cerium and aluminum on the ignition point and the oxidation resistance of magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lin Pengyu [Key Laboratory of Automobile Materials of Ministry of Education, School of Materials Science and Engineering, Nanling Campus of Jilin University, Changchun Jilin 130025 (China)], E-mail: linpengyu2000@yahoo.com.cn; Zhou Hong; Li Wei; Li Wenping; Sun Na [Key Laboratory of Automobile Materials of Ministry of Education, School of Materials Science and Engineering, Nanling Campus of Jilin University, Changchun Jilin 130025 (China); Yang Rong [Public Mathematics Teaching and Research Center, College of Mathematics, Qianwei Campus of Jilin University, Changchun Jilin 130012 (China)

    2008-09-15

    This paper focused on the interactive effect of cerium (Ce) addition and aluminum (Al) content in magnesium alloy on ignition point and oxidation resistance. Ce content played an important role in improving the oxidation resistance of Mg alloy. Ignition point ascended with increasing Ce content. 0.25 wt% Ce content in Mg alloys could greatly improve tightness of the oxide film of Mg alloys. However, when Ce content in the alloy exceeded its solid solubility, ignition point descended. Furthermore, Al content in the alloy also influenced the ignition point. The higher the Al content was, the lower the ignition point.

  4. Reduction of interface states by hydrogen treatment at the aluminum oxide/4H-SiC Si-face interface

    Directory of Open Access Journals (Sweden)

    Hironori Yoshioka

    2016-10-01

    Full Text Available Processes to form aluminum oxide as a gate insulator on the 4H-SiC Si-face are investigated to eliminate the interface state density (DIT and improve the mobility. Processes that do not involve the insertion or formation of SiO2 at the interface are preferential to eliminate traps that may be present in SiO2. Aluminum oxide was formed by atomic layer deposition with hydrogen plasma pretreatment followed by annealing in forming gas. Hydrogen treatment was effective to reduce DIT at the interface of aluminum oxide and SiC without a SiO2 interlayer. Optimization of the process conditions resulted in DIT for the metal oxide semiconductor (MOS capacitor of 1.7×1012 cm−2eV−1 at 0.2 eV, and the peak field-effect mobility of the MOS field-effect transistor (MOSFET was approximately 57 cm2V−1s−1.

  5. Effect of Polar Environments on the Aluminum Oxide Shell Surrounding Aluminum Particles: Simulations of Surface Hydroxyl Bonding and Charge.

    Science.gov (United States)

    Padhye, Richa; Aquino, Adelia J A; Tunega, Daniel; Pantoya, Michelle L

    2016-06-01

    Density functional theory (DFT) calculations were performed to understand molecular variations on an alumina surface due to exposure to a polar environment. The analysis has strong implications for the reactivity of aluminum (Al) particles passivated by an alumina shell. Recent studies have shown a link between the carrier fluid used for Al powder intermixing and the reactivity of Al with fluorine containing reactive mixtures. Specifically, flame speeds show a threefold increase when polar liquids are used to intermix aluminum and fluoropolymer powder mixtures. It was hypothesized that the alumina lattice structure could be transformed due to hydrogen bonding forces exerted by the environment that induce modified bond distances and charges and influence reactivity. In this study, the alumina surface was analyzed using DFT calculations and model clusters as isolated systems embedded in polar environments (acetone and water). The conductor-like screening model (COSMO) was used to mimic environmental effects on the alumina surface. Five defect models for specific active -OH sites were investigated in terms of structures and vibrational -OH stretching frequencies. The observed changes of the surface OH sites invoked by the polar environment were compared to the bare surface. The calculations revealed a strong connection between the impact of carrier fluid polarity on the hydrogen bonding forces between the surface OH sites and surrounding species. Changes were observed in the OH characteristic properties such as OH distances (increase), atomic charges (increase), and OH stretching frequencies (decrease); these consequently improve OH surface reactivity. The difference between medium (acetone) and strong (water) polar environments was minimal in the COSMO approximation. PMID:27175545

  6. Facile synthesis of polyaniline nanotubes using reactive oxide templates for high energy density pseudocapacitors

    KAUST Repository

    Chen, Wei

    2013-01-01

    A remarkable energy density of 84 W h kg(cell) -1 and a power density of 182 kW kg(cell) -1 have been achieved for full-cell pseudocapacitors using conducting polymer nanotubes (polyaniline) as electrode materials and ionic liquid as electrolytes. The polyaniline nanotubes were synthesized by a one-step in situ chemical polymerization process utilizing MnO2 nanotubes as sacrificial templates. The polyaniline-nanotube pseudocapacitors exhibit much better electrochemical performance than the polyaniline-nanofiber pseudocapacitors in both acidic aqueous and ionic liquid electrolytes. Importantly, the incorporation of ionic liquid with polyaniline-nanotubes has drastically improved the energy storage capacity of the PAni-nanotube pseudocapacitors by a factor of ∼5 times compared to that of the PAni-nanotube pseudocapacitors in the acidic aqueous electrolyte. Furthermore, even after 10000 cycles, the PAni-nanotube pseudocapacitors in the ionic liquid electrolyte maintain sufficient high energy density and can light LEDs for several minutes, with only 30 s quick charge. © 2013 The Royal Society of Chemistry.

  7. Fabrication of Acrylonitrile-Butadiene-Styrene Nanostructures with Anodic Alumina Oxide Templates, Characterization and Biofilm Development Test for Staphylococcus epidermidis.

    Directory of Open Access Journals (Sweden)

    Camille Desrousseaux

    Full Text Available Medical devices can be contaminated by microbial biofilm which causes nosocomial infections. One of the strategies for the prevention of such microbial adhesion is to modify the biomaterials by creating micro or nanofeatures on their surface. This study aimed (1 to nanostructure acrylonitrile-butadiene-styrene (ABS, a polymer composing connectors in perfusion devices, using Anodic Alumina Oxide templates, and to control the reproducibility of this process; (2 to characterize the physico-chemical properties of the nanostructured surfaces such as wettability using captive-bubble contact angle measurement technique; (3 to test the impact of nanostructures on Staphylococcus epidermidis biofilm development. Fabrication of Anodic Alumina Oxide molds was realized by double anodization in oxalic acid. This process was reproducible. The obtained molds present hexagonally arranged 50 nm diameter pores, with a 100 nm interpore distance and a length of 100 nm. Acrylonitrile-butadiene-styrene nanostructures were successfully prepared using a polymer solution and two melt wetting methods. For all methods, the nanopicots were obtained but inside each sample their length was different. One method was selected essentially for industrial purposes and for better reproducibility results. The flat ABS surface presents a slightly hydrophilic character, which remains roughly unchanged after nanostructuration, the increasing apparent wettability observed in that case being explained by roughness effects. Also, the nanostructuration of the polymer surface does not induce any significant effect on Staphylococcus epidermidis adhesion.

  8. Evaluation of the microstructural and photocatalytic properties of aluminum-doped zinc oxide coatings deposited by plasma spraying

    International Nuclear Information System (INIS)

    Aluminum-doped zinc oxide (AZO) material produced from a nanopowder agglomerate was deposited as a plasma-sprayed coating, and the resulting microstructural and photocatalytic properties of these coatings were investigated. The microstructure of the AZO coatings was analyzed by X-ray diffraction and scanning electron microscopy. Additionally, the photocatalytic degradation of methylene blue caused by the AZO coatings was estimated via ultraviolet–visible spectroscopy. The results of this study demonstrate that the AZO coatings deposited by plasma spraying can influence the photocatalytic degradation of methylene blue. - Highlights: • We doped aluminum (Al) in a zinc oxide (ZnO) coating using plasma spraying. • More significant recrystallization was observed after plasma spraying. • The surface of the Al-doped ZnO coating exhibited a microplatelet microstructure. • The Al-doped ZnO coating displayed high photocatalytic activities

  9. Crystalline mesoporous tungsten oxide nanoplate monoliths synthesized by directed soft template method for highly sensitive NO{sub 2} gas sensor applications

    Energy Technology Data Exchange (ETDEWEB)

    Hoa, Nguyen Duc, E-mail: ndhoa@itims.edu.vn [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST) (Viet Nam); Duy, Nguyen Van [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST) (Viet Nam); Hieu, Nguyen Van, E-mail: hieu@itims.edu.vn [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST) (Viet Nam)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► Mesoporous WO{sub 3} nanoplate monoliths were obtained by direct templating synthesis. ► Enable effective accession of the analytic molecules for the sensor applications. ► The WO{sub 3} sensor exhibited a high performance to NO{sub 2} gas at low temperature. -- Abstract: Controllable synthesis of nanostructured metal oxide semiconductors with nanocrystalline size, porous structure, and large specific surface area is one of the key issues for effective gas sensor applications. In this study, crystalline mesoporous tungsten oxide nanoplate-like monoliths with high specific surface areas were obtained through instant direct-templating synthesis for highly sensitive nitrogen dioxide (NO{sub 2}) sensor applications. The copolymer soft template was converted into a solid carbon framework by heat treatment in an inert gas prior to calcinations in air to sustain the mesoporous structure of tungsten oxide. The multidirectional mesoporous structures of tungsten oxide with small crystalline size, large specific surface area, and superior physical characteristics enabled the rapid and effective accession of analytic gas molecules. As a result, the sensor response was enhanced and the response and recovery times were reduced, in which the mesoporous tungsten oxide based gas sensor exhibited a superior response of 21,155% to 5 ppm NO{sub 2}. In addition, the developed sensor exhibited selective detection of low NO{sub 2} concentration in ammonia and ethanol at a low temperature of approximately 150 °C.

  10. Application of the Generic Modeling Template Approach to Unsaturated Fatty Acid Oxidation and Crystallization Systems

    DEFF Research Database (Denmark)

    Fedorova, Marina; Papadakis, Emmanouil; Meisler, Kresten Troelstrup;

    2014-01-01

    for following the modelling workflow steps, guidance through the steps , as well as providing additional information and comments. The application of the tool is highlighted with two case studies: oxidation of unsaturated acid with hydrogen peroxide and modeling of a crystal lization operation...... for the paracetamol-ethanol system....

  11. Pomegranate Alleviates Oxidative Damage and Neurotransmitter Alterations in Rats Brain Exposed to Aluminum Chloride and/or Gamma Radiation

    International Nuclear Information System (INIS)

    Aluminum and gamma radiation, both are potent neurotoxins and have been implicated in many human neuro degenerative diseases. The present study was designed to investigate the role of pomegranate in alleviating oxidative damage and alteration of neurotransmitters in the brain of rats exposed to aluminum chloride (AlCl3), and/or gamma radiation (IR). The results revealed that rats whole body exposed to γ- rays, (1 Gy/week up to 4 Gy), and/or administered aluminum chloride (35 mg/kg body weight), via gavages for 4 weeks, resulted in brain tissue damage, featuring by significant increase of the level of thiobarbituric acid reactive substances (TBARS), and advanced oxidation protein products (AOPP), associated with significant decrease of superoxide dismutase (SOD) and catalase (CAT) activities, as well as glutathione (GSH) content indicating occurrence of oxidative stress. A significant decrease of serotonin (5-HT) level associated with a significant increase of 5-hydroxyindole acetic acid (5-HIAA), in addition to a significant decrease in dopamine (DA), norepinephrine (NE) and epinephrine (EPI) contents recorded at the 1st, 7th and 14th day post-irradiation, indicating alterations in the metabolism of brain monoamines. On the other hand, the results exhibited that, supplementation of rats with pomegranate, via gavages, at a dose of 3 ml /kg body weight/ day, for 4 weeks along with AlCl3 with or without radiation has significantly ameliorated the changes occurred in the mentioned parameters and the values returned close to the normal ones. It could be concluded that pomegranate, by its antioxidant constituents might antagonize brain oxidative damage and minimize the severity of aluminum (Al), and/or radiation-induced neurotransmitters disorders

  12. Distribution of electric field near the surface of the aluminum oxide particle in the dust-electron thermal plasma

    International Nuclear Information System (INIS)

    We obtained the equation, which describes the distribution of electrical field in an equilibrium dust-electron plasma taking into account parameters of the electron gas inside the dust particles. The inclusion of these parameters performed on the basis of the model of ''solid- state plasma'', considering the condensed particle system as the ion core and the free electron gas. These calculations are performed for aluminum oxide particles

  13. Liquid crystal alignment in nanoporous anodic aluminum oxide layer for LCD panel applications.

    Science.gov (United States)

    Hong, Chitsung; Tang, Tsung-Ta; Hung, Chi-Yu; Pan, Ru-Pin; Fang, Weileun

    2010-07-16

    This paper reports the implementation and integration of a self-assembled nanoporous anodic aluminum oxide (np-AAO) film and liquid crystal (LC) on an ITO-glass substrate for liquid crystal display (LCD) panel applications. An np-AAO layer with a nanopore array acts as the vertical alignment layer to easily and uniformly align the LC molecules. Moreover, the np-AAO nanoalignment layer provides outstanding material properties, such as being inorganic with good transmittance, and colorless on ITO-glass substrates. In this application, an LCD panel, with the LC on the np-AAO nanoalignment layer, is successfully implemented on an ITO-glass substrate, and its performance is demonstrated. The measurements show that the LCD panel, consisting of an ITO-glass substrate and an np-AAO layer, has a transmittance of 60-80%. In addition, the LCD panel switches from a black state to a bright state at 3 V(rms), with a response time of 62.5 ms. In summary, this paper demonstrates the alignment of LC on an np-AAO layer for LCD applications.

  14. Removal of trivalent chromium from aqueous solution using aluminum oxide hydroxide.

    Science.gov (United States)

    Bedemo, Agaje; Chandravanshi, Bhagwan Singh; Zewge, Feleke

    2016-01-01

    Water is second most essential for human being. Contamination of water makes it unsuitable for human consumption. Chromium ion is released to water bodies from various industries having high toxicity which affects the biota life in these waters. In this study aluminum oxide hydroxide was tested for its efficiency to remove trivalent chromium from aqueous solutions through batch mode experiments. Chromium concentrations in aqueous solutions and tannery waste water before and after adsorption experiments were determined using flame atomic absorption spectrometry. The effects of pH, contact time, initial concentration and adsorbent dosage on the adsorption of Cr(III) were studied. The study revealed that more than 99 % removal of Cr(III) was achieved over wide range of initial pH (3-10). The optimum conditions for the removal of Cr(III) were found to be at pH 4-6 with 40 g/L adsorbent dose at 60 min of contact time. The adsorption capacity was assessed using Langmuir and Freundlich isotherms. The equilibrium data at varying adsorbent dose obeyed the two isotherms. The adsorbent was found to be efficient for the removal of Cr(III) from tannery waste effluent. PMID:27547663

  15. Effects of anodic aluminum oxide membrane on performance of nanostructured solar cells

    Science.gov (United States)

    Dang, Hongmei; Singh, Vijay

    2015-05-01

    Three nanowire solar cell device configurations have been fabricated to demonstrate the effects of the host anodized aluminum oxide (AAO) membrane on device performance. The three configurations show similar transmittance spectra, indicating that AAO membrane has negligible optical absorption. Power conversion efficiency (PCE) of the device is studied as a function of the carrier transport and collection in cell structures with and without AAO membrane. Free standing nanowire solar cells exhibit PCE of 9.9%. Through inclusion of AAO in solar cell structure, interface defects and traps caused by humidity and oxygen are reduced, and direct contact of CdTe tentacles with SnO2 and formation of micro shunt shorts are prevented; hence PCE is improved to 11.1%-11.3%. Partially embedded nanowire solar cells further reduce influence of non-ideal and non-uniform nanowire growth and generate a large amount of carriers in axial direction and also a small quantity of carriers in lateral direction, thus becoming a promising solar cell structure. Thus, including AAO membrane in solar cell structure provides favorable electro-optical properties as well as mechanical advantages.

  16. Neutron spectrum measurements in the aluminum oxide filtered beam facility at the Brookhaven Medical Research Reactor

    International Nuclear Information System (INIS)

    Neutron spectrum measurements were performed on the aluminum oxide filter installed in the Brookhaven Medical Research Reactor (BMRR). For these measurements, activation foils were irradiated at the exit port of the beam facility. A technique based on dominant resonances in selected activation reactions was used to measure the epithermal neutron spectrum. The fast and intermediate-energy ranges of the neutron spectrum were measured by threshold reactions and 10B-shielded 235U fission reactions. Neutron spectral data were derived from the activation data by two approaches: (1) a short analysis which yields neutron flux values at the energies of the dominant or primary resonances in the epithermal activation reactions and integral flux data for neutrons above corresponding threshold or pseudo-threshold energies, and (2) the longer analysis which utilized all the activation data in a full-spectrum, unfolding process using the FERRET spectrum adjustment code. This paper gives a brief description of the measurement techniques, analysis methods, and the results obtained

  17. Remarkable enhancement of upconversion luminescence on 2-D anodic aluminum oxide photonic crystals.

    Science.gov (United States)

    Wang, He; Yin, Ze; Xu, Wen; Zhou, Donglei; Cui, Shaobo; Chen, Xu; Cui, Haining; Song, Hongwei

    2016-05-21

    Lanthanide-doped upconversion nanoparticles (UCNPs) are attracting extensive attention due to their unique physical properties and great application potential. However, the lower luminescence quantum yield/strength is still an obstacle for real application. Local field modulation is a promising method to highly enhance the upconversion luminescence (UCL) of the UCNPs. In this work, a novel kind of two-dimensional photonic crystal (2D-PC), anodic aluminum oxides (AAOs), was explored to improve the UCL of NaYF4:Yb(3+),Er(3+) nanoplates (NPs). An optimum enhancement factor (EF) of 65-fold was obtained for the overall intensity of Er(3+) under 980 nm excitation, and 130-fold for the red emission. Systematic studies indicate that UCL enhancement mainly originates from the enlargement of the excitation field by scattering and reflection of AAO PCs. It should also be highlighted that the modulation of 2D-PC on the UCL of NaYF4:Yb(3+),Er(3+) NPs demonstrates weak size-dependent and thickness-dependent behavior, which is well consistent with the stimulated electromagnetic field distribution by the finite difference time domain (FDTD) method. PMID:27139324

  18. Nanosecond laser ablation processes in aluminum-doped zinc-oxide for photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Canteli, D., E-mail: david.canteli@ciemat.es [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain); Fernandez, S. [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain); Molpeceres, C. [Centro Laser, Universidad Politecnica de Madrid, Ctra. de Valencia Km 7.3, 28031 Madrid (Spain); Torres, I.; Gandia, J.J. [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer A study of the ablation of AZO thin films deposited at different temperature conditions with nanosecond UV laser light for photovoltaic devices has been performed. Black-Right-Pointing-Pointer The ablation threshold of AZO thin films was measured and related with the absorption coefficient of the films at the laser wavelength, showing a direct correspondence. Black-Right-Pointing-Pointer A change in the material structure in the areas closest to the edges of laser grooves made in samples deposited at temperatures below 100 Degree-Sign C was observed and studied. - Abstract: Aiming to a future use in thin film solar modules, the processing of aluminum doped zinc oxide thin films with good optoelectronic properties with a nanosecond-pulsed ultraviolet laser has been studied. The ablation threshold fluence of the films has been determined and associated with the material properties. The ablation process has been optimized and grooves with good properties for photovoltaic devices have been obtained. The morphology of the ablated surfaces has been observed by confocal microscopy and its structure has been characterized by Raman spectroscopy. The influence of ablation parameters like focus distance, pulse energy and repetition frequency in the groove morphology has been studied with special attention to the thermal effects on the material structure.

  19. Sex-Dependent Depression-Like Behavior Induced by Respiratory Administration of Aluminum Oxide Nanoparticles.

    Science.gov (United States)

    Zhang, Xin; Xu, Yan; Zhou, Lian; Zhang, Chengcheng; Meng, Qingtao; Wu, Shenshen; Wang, Shizhi; Ding, Zhen; Chen, Xiaodong; Li, Xiaobo; Chen, Rui

    2015-12-01

    Ultrafine aluminum oxide, which are abundant in ambient and involved occupational environments, are associated with neurobehavioral alterations. However, few studies have focused on the effect of sex differences following exposure to environmental Al₂O₃ ultrafine particles. In the present study, male and female mice were exposed to Al₂O₃ nanoparticles (NPs) through a respiratory route. Only the female mice showed depression-like behavior. Although no obvious pathological changes were observed in mice brain tissues, the neurotransmitter and voltage-gated ion channel related gene expression, as well as the small molecule metabolites in the cerebral cortex, were differentially modulated between male and female mice. Both mental disorder-involved gene expression levels and metabolomics analysis results strongly suggested that glutamate pathways were implicated in sex differentiation induced by Al₂O₃ NPs. Results demonstrated the potential mechanism of environmental ultrafine particle-induced depression-like behavior and the importance of sex dimorphism in the toxic research of environmental chemicals. PMID:26690197

  20. Sex-Dependent Depression-Like Behavior Induced by Respiratory Administration of Aluminum Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Xin Zhang

    2015-12-01

    Full Text Available Ultrafine aluminum oxide, which are abundant in ambient and involved occupational environments, are associated with neurobehavioral alterations. However, few studies have focused on the effect of sex differences following exposure to environmental Al2O3 ultrafine particles. In the present study, male and female mice were exposed to Al2O3 nanoparticles (NPs through a respiratory route. Only the female mice showed depression-like behavior. Although no obvious pathological changes were observed in mice brain tissues, the neurotransmitter and voltage-gated ion channel related gene expression, as well as the small molecule metabolites in the cerebral cortex, were differentially modulated between male and female mice. Both mental disorder-involved gene expression levels and metabolomics analysis results strongly suggested that glutamate pathways were implicated in sex differentiation induced by Al2O3 NPs. Results demonstrated the potential mechanism of environmental ultrafine particle-induced depression-like behavior and the importance of sex dimorphism in the toxic research of environmental chemicals.

  1. Vibration Durability Testing of Nickel Cobalt Aluminum Oxide (NCA Lithium-Ion 18650 Battery Cells

    Directory of Open Access Journals (Sweden)

    James Michael Hooper

    2016-04-01

    Full Text Available This paper outlines a study undertaken to determine if the electrical performance of Nickel Cobalt Aluminum Oxide (NCA 3.1 Ah 18650 battery cells can be degraded by road induced vibration typical of an electric vehicle (EV application. This study investigates if a particular cell orientation within the battery assembly can result in different levels of cell degradation. The 18650 cells were evaluated in accordance with Society of Automotive Engineers (SAE J2380 standard. This vibration test is synthesized to represent 100,000 miles of North American customer operation at the 90th percentile. This study identified that both the electrical performance and the mechanical properties of the NCA lithium-ion cells were relatively unaffected when exposed to vibration energy that is commensurate with a typical vehicle life. Minor changes observed in the cell’s electrical characteristics were deemed not to be statistically significant and more likely attributable to laboratory conditions during cell testing and storage. The same conclusion was found, irrespective of cell orientation during the test.

  2. Prediction model for oxide thickness on aluminum alloy cladding during irradiation

    International Nuclear Information System (INIS)

    An empirical model predicting the oxide film thickness on aluminum alloy cladding during irradiation has been developed as a function of irradiation time, temperature, heat flux, pH, and coolant flow rate. The existing models in the literature are neither consistent among themselves nor fit the measured data very well. They also lack versatility for various reactor situations such as a pH other than 5, high coolant flow rates, and fuel life longer than ∼1200 hrs. Particularly, they were not intended for use in irradiation situations. The newly developed model is applicable to these in-reactor situations as well as ex-reactor tests, and has a more accurate prediction capability. The new model demonstrated with consistent predictions to the measured data of UMUS and SIMONE fuel tests performed in the HFR, Petten, tests results from the ORR, and IRIS tests from the OSIRIS and to the data from the out-of-pile tests available in the literature as well. (author)

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  5. Fabrication of large-area self-organizing gold nanostructures on a porous Al2O3 template for application as a SERS-substrate

    DEFF Research Database (Denmark)

    Nielsen, Peter; Hassing, Søren; Albrektsen, Ole;

    A new technique for fabrication of large-area self-organizing variably ordered gold nanostructures with sub-10 nm gaps on templates of hexagonally ordered porous anodic aluminum oxide is demonstrated. The size as well as the interparticle distance of the fabricated gold nanostructures are adjusted...... by application of various electrolytes used in anodization of the aluminum template and the thickness of gold sputter-coated on the pore layer. The fabricated substrates are characterized by SEM, and the applicability as SERS substrates is investigated by adsorption of rhodamine 6G on the nanostructures...

  6. Growth Mechanism and Optimized Parameters to Synthesize Nation-115 Nanowire Arrays with Anodic Aluminium Oxide Membranes as Templates

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lu; PAN Cao-Feng; ZHU Jing

    2008-01-01

    @@ Nafion-115 nanowire arrays are synthesized with an extrusion method using AAO membranes as templates. It is indicated that the vacuum treating of AAO templates before surface decoration plays an important role in obtaining high filling rate of the Nafion-115 nanowires in the AAO templates, while the concentration of Nafion-115 DMSO solutions does not affect the filling rate greatly. The optimized parameters to synthesize the Nafion-115 nanowire arrays are studied. The filling rate of the Nafion-115 nanowires in the AAO templates synthesized with the optimized parameters is about 95%. The growth mechanism of Nafion-115 nanowires is discussed to qualitatively explain the experimental results.

  7. Microstructure and corrosion behavior of micro-arc oxidation coating on 6061 aluminum alloy pre-treated by high-temperature oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Dejiu, E-mail: sdj217@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Li, Guolong, E-mail: lglysu@163.com [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Guo, Changhong [College of Mechanical Engineering, Yanshan University, Qinhuangdao 066004 (China); Zou, Jie [China Aviation Industry Chengdu Engine (Group) Co. Ltd., Chengdu 610503 (China); Cai, Jingrui; He, Donglei; Ma, Haojie; Liu, Fangfei [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2013-12-15

    In this paper, we investigate the microstructure and corrosion behavior of the micro-arc oxidation (MAO) coating on 6061 aluminum alloy that pre-treated by high-temperature oxidation (HTO). Microstructure, chemical and corrosion behaviors of the fabricated MAO ceramic coatings were studied by using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and electrochemical corrosion tests. The results reveal that the pre-fabricated HTO film remarkably affects the formation of the MAO coating, leads to an enriched content of Mg, and decreases the compactness of the coating. The corrosion resistance of the 6061 aluminum alloy has been significantly improved by treatments of HTO, normal MAO (NMAO) and HTO pre-treated MAO (HTO-MAO), and the NMAO coating exhibits the best corrosion performance. The content of Mg in HTO pre-fabricated film is remarkedly higher than that in the substrate, which greatly influences the formation of the MAO coating.

  8. Mechanochemical reactions and strengthening in epoxy-cast aluminum iron-oxide mixtures

    Science.gov (United States)

    Ferranti, Louis, Jr.

    2007-12-01

    -viscoplastic deformation and brittle fracture behaviors. Significant elastic and plastic deformation during both loading and unloading stages is observed, with approximately 50% elastic recovery of total axial strain occurring rapidly (tens of microseconds) after impact. Coupling high-speed camera images and velocity interferometry measurements shows that the elastic recovery coincides with peak axial strain and the elastic and plastic wave interaction. The incorporation of nano-scale aluminum particles enhances the dynamic stress-strain response and significantly improves the composites' resilience to impact as compared to pure epoxy, and with the use of micron-scale aluminum particles. Post-mortem analysis of recovered Taylor impacted specimens indicates evidence of early stages of strain-induced reactions occurring at select stress, strain, and strain rates. The observed reaction products correlate with results of thermal analysis, which include DTA and in situ high temperature x-ray diffraction (HTXRD). Central to this study was the interaction of metal-oxide powder mixtures with the epoxy matrix and how their chemical and mechanical properties balance to form a structural energetic material system. The study focuses on describing the underlying principles governing the deformation and fracture behavior, processing characteristics of epoxy-cast Al+Fe2O3 powder mixtures, mechanochemical sensitivity, and reaction response. In order to accomplish this, the effects of size, morphology, and distribution of particles were evaluated based on mechanical and chemical response to high pressures and combined stress-strain states using time-resolved measurements.

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

    Science.gov (United States)

    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.

  10. ATOMIC LAYER DEPOSITION OF TITANIUM OXIDE THIN FILMS ONNANOPOROUS ALUMINA TEMPLATES FOR MEDICAL APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Brigmon, R.

    2009-05-05

    Nanostructured materials may play a significant role in controlled release of pharmacologic agents for treatment of cancer. Many nanoporous polymer materials are inadequate for use in drug delivery. Nanoporous alumina provides several advantages over other materials for use in controlled drug delivery and other medical applications. Atomic layer deposition was used to coat all the surfaces of the nanoporous alumina membrane in order to reduce the pore size in a controlled manner. Both the 20 nm and 100 nm titanium oxide-coated nanoporous alumina membranes did not exhibit statistically lower viability compared to the uncoated nanoporous alumina membrane control materials. In addition, 20 nm pore size titanium oxide-coated nanoporous alumina membranes exposed to ultraviolet light demonstrated activity against Escherichia coli and Staphylococcus aureus bacteria. Nanostructured materials prepared using atomic layer deposition may be useful for delivering a pharmacologic agent at a precise rate to a specific location in the body. These materials may serve as the basis for 'smart' drug delivery devices, orthopedic implants, or self-sterilizing medical devices.

  11. Constructing inverse V-type TiO{sub 2}-based photocatalyst via bio-template approach to enhance the photosynthetic water oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jinghui; Zhou, Han; Ding, Jian; Zhang, Fan; Fan, Tongxiang, E-mail: txfan@sjtu.edu.cn; Zhang, Di

    2015-08-30

    Graphical abstract: Inverse V-type TiO{sub 2}-based photocatalyst was synthesized by using cross-linked titanium precursor to duplicate bio-template. - Highlights: • Cross-linked titanium precursor can facilitate an accurate duplication of templates. • In situ deposition of Ag{sup 0} from AgBr can maintain the completeness of surface structure. • Perfect inverse V-type Ag{sup 0}/TiO{sub 2} can achieve efficient water oxidation. - Abstract: Bio-template approach was employed to construct inverse V-type TiO{sub 2}-based photocatalyst with well distributed AgBr in TiO{sub 2} matrix by making dead Troides Helena wings with inverse V-type scales as the template. A cross-linked titanium precursor with homogenous hydrolytic rate, good liquidity, and low viscosity was employed to facilitate a perfect duplication of the template and the dispersion of AgBr based on appropriate pretreatment of the template by alkali and acid. The as-synthesized inverse V-type TiO{sub 2}/AgBr can be turned into inverse V-type TiO{sub 2}/Ag{sup 0} from AgBr photolysis during photocatalysis to achieve in situ deposition of Ag{sup 0} in TiO{sub 2} matrix, by this approach, to avoid the deformation of surface microstructure inherited from the template. The result showed that the cooperation of perfect inverse V-type structure and the well distributed TiO{sub 2}/Ag{sup 0} microstructures can efficiently boost the photosynthetic water oxidation compared to non-inverse V-type TiO{sub 2}/Ag{sup 0} and TiO{sub 2}/Ag{sup 0} without using template. The anti-reflection function of inverse V-type structure and the plasmatic effect of Ag{sup 0} might be able to account for the enhanced photon capture and efficient photoelectric conversion.

  12. Sacrificial Template-Based Synthesis of Unified Hollow Porous Palladium Nanospheres for Formic Acid Electro-Oxidation

    Directory of Open Access Journals (Sweden)

    Xiaoyu Qiu

    2015-06-01

    Full Text Available Large scale syntheses of uniform metal nanoparticles with hollow porous structure have attracted much attention owning to their high surface area, abundant active sites and relatively efficient catalytic activity. Herein, we report a general method to synthesize hollow porous Pd nanospheres (Pd HPNSs by templating sacrificial SiO2 nanoparticles with the assistance of polyallylamine hydrochloride (PAH through layer-by-layer self-assembly. The chemically inert PAH is acting as an efficient stabilizer and complex agent to control the synthesis of Pd HPNSs, probably accounting for its long aliphatic alkyl chains, excellent coordination capability and good hydrophilic property. The physicochemical properties of Pd HPNSs are thoroughly characterized by various techniques, such as transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy. The growth mechanism of Pd HPNSs is studied based on the analysis of diverse experimental observations. The as-prepared Pd HPNSs exhibit clearly enhanced electrocatalytic activity and durability for the formic oxidation reaction (FAOR in acid medium compared with commercial Pd black.

  13. Effects of aluminum additions to gas atomized reaction synthesis produced oxide dispersion strengthened alloys

    Science.gov (United States)

    Spicher, Alexander Lee

    The production of an aluminum containing ferritic oxide dispersion strengthened (ODS) alloy was investigated. The production method used in this study was gas atomization reaction synthesis (GARS). GARS was chosen over the previously commercial method of mechanical alloying (MA) process due to complications from this process. The alloy compositions was determined from three main components; corrosion resistance, dispersoid formation, and additional elements. A combination of Cr and Al were necessary in order to create a protective oxide in the steam atmosphere that the boiler tubing in the next generation of coal-fired power plants would be exposed to. Hf and Y were chosen as dispersoid forming elements due to their increased thermal stability and potential to avoid decreased strength caused by additions of Al to traditional ODS materials. W was used as an additive due to benefits as a strengthener as well as its benefits for creep rupture time. The final composition chosen for the alloy was Fe-16Cr-12Al-0.9W-0.25Hf-0.2Y at%. The aforementioned alloy, GA-1-198, was created through gas atomization with atomization gas of Ar-300ppm O2. The actual composition created was found to be Fe-15Cr-12.3Al-0.9W-0.24Hf-0.19Y at%. An additional alloy that was nominally the same without the inclusion of aluminum was created as a comparison for the effects on mechanical and corrosion properties. The actual composition of the comparison alloy, GA-1-204, was Fe-16Cr-0Al-0.9W-0.25Hf-0.24Y at%. An investigation on the processing parameters for these alloys was conducted on the GA-1-198 alloy. In order to predict the necessary amount of time for heat treatment, a diffusion study was used to find the diffusion rate of oxygen in cast alloys with similar composition. The diffusion rate was found to be similar to that of other GARS compositions that have been created without the inclusion of aluminum. The effect of heat treatment time was investigated with temperatures of 950°C, 1000

  14. Fabrication of nanostructure via self-assembly of nanowires within the AAO template

    Directory of Open Access Journals (Sweden)

    Brust Mathias

    2006-01-01

    Full Text Available AbstractThe novel nanostructures are fabricated by the spatial chemical modification of nanowires within the anodic aluminum oxide (AAO template. To make the nanowires better dispersion in the aqueous solution, the copper is first deposited to fill the dendrite structure at the bottom of template. During the process of self-assembly, the dithiol compound was used as the connector between the nanowires and nanoparticles by a self-assembly method. The nanostructures of the nano cigars and structure which is containing particles junction are characterized by transmission electron microscopy (TEM. These kinds of novel nanostructure will be the building blocks for nanoelectronic and nanophotonic devices.

  15. Fabrication of Cu nano-arrays by template method and their characterizations

    Institute of Scientific and Technical Information of China (English)

    REN Xin; HUANG Xinmin; ZHANG Huhai; HE Meiqing

    2007-01-01

    Cu nanotubes and nanowires were fabricated by electroless deposition using porous aluminum oxide membrane as template in coating bath at room temperature.The images of Cu nanotubes and nanowires are obtained by transmission electron microscopy(TEM).X-ray diffractometry (XRD)is employed to study the morphology.Results indicate mat the success of fabrication depends on the reducing process of pore treatment.The outer diameter of Cu nanotubes can be controlled by adjusting the aperture of anodic alumina membranes (AAM)template,and the thickness of the tube wall can be controlled by deposition time.The morphology of Cu nanotubes and nanowires are polycrystalline.

  16. Characterization of Nano-scale Aluminum Oxide Transport Through Porous Media

    Science.gov (United States)

    Norwood, Sasha Norien

    Land application of biosolids has become common practice in the United States as an alternative to industrial fertilizers. Although nutrient rich, biosolids have been found to contain high concentrations of unregulated and/or unrecognized emerging contaminants (e.g., pharmaceuticals, personal care products) while containing a significant fraction of inorganic nano-scale colloidal materials such as oxides of iron, titanium, and aluminum. Given their reactivity and small size, there are many questions concerning the potential migration of these nano-sized colloidal materials through the soil column and into our surface and groundwater bodies. Transport of emerging pollutants of concern through the soil column, at minimum, is impacted by colloidal properties (e.g., chemical composition, shape, aggregation kinetics), solution chemistry (e.g., pH, ionic strength, natural organic matter), and water flow velocity. The purpose of this current research was to characterize the long-term transport behavior of aluminum oxide nanoparticles (Al 2O3) through a natural porous media with changes in pH, aqueous-phase concentration, pore-water velocity and electrolyte valence. Additionally, deposition rates during the initial stages of deposition were compared to several models developed based on colloid filtration theory and DLVO stability theory. Benchtop column laboratory experiments showed that, under environmentally relevant groundwater conditions, Al2O3 nanoparticles are mobile through saturated porous media. Mobility increased under conditions in which the nanoparticles and porous media were of like charge (pH 9). Changes in linear pore water velocity, under these same high pH conditions, showed similar transport behavior with little mass retained in the system. Deposition is believed to be kinetically controlled at pH 9, as evidenced by the slightly earlier breakthrough as flow rate increased and was further supported by observed concentration effects on the arrival wave

  17. Rapid susceptibility testing and microcolony analysis of Candida spp. cultured and imaged on porous aluminum oxide.

    Directory of Open Access Journals (Sweden)

    Colin J Ingham

    Full Text Available BACKGROUND: Acquired resistance to antifungal agents now supports the introduction of susceptibility testing for species-drug combinations for which this was previously thought unnecessary. For pathogenic yeasts, conventional phenotypic testing needs at least 24 h. Culture on a porous aluminum oxide (PAO support combined with microscopy offers a route to more rapid results. METHODS: Microcolonies of Candida species grown on PAO were stained with the fluorogenic dyes Fun-1 and Calcofluor White and then imaged by fluorescence microscopy. Images were captured by a charge-coupled device camera and processed by publicly available software. By this method, the growth of yeasts could be detected and quantified within 2 h. Microcolony imaging was then used to assess the susceptibility of the yeasts to amphotericin B, anidulafungin and caspofungin (3.5 h culture, and voriconazole and itraconazole (7 h culture. SIGNIFICANCE: Overall, the results showed good agreement with EUCAST (86.5% agreement; n = 170 and E-test (85.9% agreement; n = 170. The closest agreement to standard tests was found when testing susceptibility to amphotericin B and echinocandins (88.2 to 91.2% and the least good for the triazoles (79.4 to 82.4%. Furthermore, large datasets on population variation could be rapidly obtained. An analysis of microcolonies revealed subtle effects of antimycotics on resistant strains and below the MIC of sensitive strains, particularly an increase in population heterogeneity and cell density-dependent effects of triazoles. Additionally, the method could be adapted to strain identification via germ tube extension. We suggest PAO culture is a rapid and versatile method that may be usefully adapted to clinical mycology and has research applications.

  18. Synthesis of ZnSe semiconductor nanodot arrays by templated PVD

    Energy Technology Data Exchange (ETDEWEB)

    Valeev, Rishat; Beltukov, Artemiy [Physico-Technical Institute of UB RAS, Kirova st. 132, 426000 Izhevsk (Russian Federation); Udmurt State University, Universitetskaya st. 1, 426034 Izhevsk (Russian Federation); Romanov, Eduard; Krylov, Petr [Udmurt State University, Universitetskaya st. 1, 426034 Izhevsk (Russian Federation); Deev, Andrew [Physico-Technical Institute of UB RAS, Kirova st. 132, 426000 Izhevsk (Russian Federation); Napolski, Kirill; Eliseev, Andrei [Faculty of Material Sciences, Lomonosov' s Moscow State University, Leninskie Gory st. 1, 119991 Moscow (Russian Federation); Mezentsev, Nikolai [Budker Institute of Nuclear Physics of SB RAS, Lavrentiev st. 11, 630090 Novosibirsk (Russian Federation); Kriventsov, Vladimir [Boreskov Institute of Catalysis of SB RAS, Lavrentiev st. 5, 630090 Novosibirsk (Russian Federation)

    2010-06-15

    Here we report a novel approach for preparation of ZnSe nanodot arrays by physical vapor deposition on porous aluminum oxide templates possessing ordered system of channels. The structure of nanodot arrays was investigated by scanning electron microscopy and EXAFS-spectroscopy. The geometry of nanodots and local atomic structure parameters like the interatomic distances and coordination numbers of Zn and Se atoms are reported. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Fabrication of one-dimensional ZnO nanotube and nanowire arrays with an anodic alumina oxide template via electrochemical deposition

    International Nuclear Information System (INIS)

    In this work, two kinds of one-dimensional ZnO nanowires (NWs) and nanotubes (NTs) were synthesized by using electrochemical deposition with the aid of a high aspect ratio anodic alumina oxide (AAO) template. ZnO NWs and NTs were characterized by using X-ray diffraction, field emission scanning microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. An AAO template was fabricated by two-step anodization in 0.3 M oxalic acid with a voltage of 80 V. The thickness and channel diameter of the AAO template were about 150 μm and 120–150 nm, respectively. The morphologies of the ZnO nanostructures synthesized under 20 vol.% H2O2 with various electrolyte concentrations of 0.1 M and 0.5 M ZnSO4, were NTs and NWs, respectively. Both NTs and NWs were uniform in size, which corresponded to the sizes of AAO pores. The thickness of the NTs walls can be controlled based on the deposition time and current density. The crystallinity of the ZnO NTs and NWs annealing in the air were restricted by AAO pore. The growth of the ZnO NTs and NWs was caused by heterogeneous nucleation, and different growth rates through the wall of the AAO will result in different nanostructures, with the growth of the NTs being slower than that of the NWs. - Highlights: • Templated electrodeposition of ZnO nanotubes (NTs) and nanowires (NWs) • ZnO NTs and NWs fabricated using anodic alumina oxide templates • The growth mechanism of ZnO NTs and NWs is modeled

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

    Energy Technology Data Exchange (ETDEWEB)

    Miikkulainen, Ville, E-mail: ville.miikkulainen@helsinki.fi; Nilsen, Ola; Fjellvåg, Helmer [Centre for Materials Science and Nanotechnology (SMN), Department of Chemistry, University of Oslo, P.O. Box 1126 Blindern, NO-0318 Oslo (Norway); Li, Han; King, Sean W. [Intel Corporation, 5200 NE Elam Young Parkway, Hillsboro, Oregon 97124 (United States); Laitinen, Mikko; Sajavaara, Timo [Department of Physics, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä (Finland)

    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.

  1. Preparation of Chromium Oxide Coatings on Aluminum Borate Whiskers by a Hydrothermal Deposition Process

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Aluminum borate whiskers (9Al2O32B2O3) can be used to reinforce aluminum alloys to produce light and strong composites. However, the adverse interfacial reactions between the whiskers and the aluminum alloys inhibit their practical uses; therefore, a protective coating is needed on whiskers. In this work, aluminum borate whiskers were coated with chromium-coating deposits in a hydrothermal solution containing CrCl3, Na2C4H4O6, NaPH2O2, and H3BO3. The presence of the impurity P in the hydrothermal deposits can be avoided by reducing the amount of NaPH2O2 in the coating solution. Thermodynamic analysis was used to discuss the behavior of ions in the coating process. The subsequent heating of the hydrothermal products in air at 800 ℃ yielded smooth Cr2O3 films with a thickness of 0.060.07 μm.

  2. Hydrogen absorption in solid aluminum during high-temperature steam oxidation

    Science.gov (United States)

    Andreev, L. A.; Gelman, B. G.; Zhukhovitskiy, A. A.

    1979-01-01

    Hydrogen is emitted by aluminum heated in a vacuum after high-temperature steam treatment. Wire samples are tested for this effect, showing dependence on surface area. Two different mechanisms of absorption are inferred, and reactions deduced.

  3. Reversible post-breakdown conduction in aluminum oxide-polymer capacitors

    OpenAIRE

    CHEN, Qian; Gomes, HL; Rocha, PRF; De Leeuw,; Meskers, SCJ Stefan

    2013-01-01

    Aluminum/Al2O3/polymer/metal capacitors submitted to a low-power constant current stress undergo dielectric breakdown. The post-breakdown conduction is metastable, and over time the capacitors recover their original insulating properties. The decay of the conduction with time follows a power law (1/t) α . The magnitude of the exponent α can be raised by application of an electric field and lowered to practically zero by optical excitation of the polyspirofluorene polymer. The metastable condu...

  4. Syntheses, structures, and ionic conductivities of perovskite-structured lithium–strontium–aluminum/gallium–tantalum-oxides

    Energy Technology Data Exchange (ETDEWEB)

    Phraewphiphat, Thanya, E-mail: thanya@echem.titech.ac.jp [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8502 (Japan); Iqbal, Muhammad, E-mail: iqbal@echem.titech.ac.jp [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8502 (Japan); Suzuki, Kota, E-mail: ksuzuki@echem.titech.ac.jp [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8502 (Japan); Matsuda, Yasuaki, E-mail: matsuda@chem.mie-u.ac.jp [Department of Chemistry, Mie University, 1577 Kurimamachiyacho, Tsu, Mie 514-8507 (Japan); Yonemura, Masao, E-mail: masao.yonemura@kek.jp [High Energy Accelerator Research Organization, Tokai-mura, Naka-gun, Ibaraki 319-1106 (Japan); Hirayama, Masaaki, E-mail: hirayama@echem.titech.ac.jp [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8502 (Japan); Kanno, Ryoji, E-mail: kanno@echem.titech.ac.jp [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8502 (Japan)

    2015-05-15

    The ionic conductivities of new perovskite-structured lithium–strontium–aluminum/gallium–tantalum oxides were investigated. Solid solutions of the new perovskite oxides, (Li{sub x}Sr{sub 1−x})(Al{sub (1−x)/2}Ta{sub (1+x)/2})O{sub 3} and (Li{sub x}Sr{sub 1−x})(Ga{sub (1−x)/2}Ta{sub (1+x)/2})O{sub 3}, were synthesized using a ball-milled-assisted solid-state method. The partial substitution of the smaller Ga{sup +3} for Ta{sup +5} resulted in new compositions, the structures of which were determined by neutron diffraction measurements using a cubic perovskite structural model with the Pm−3m space group. Vacancies were introduced into the Sr(Li) sites by the formation of solid solutions with compositions (Li{sub x}Sr{sub 1−x−y}☐{sub y})(Ga{sub [(1−x)/2]−y}Ta{sub [(1+x)/2]+y})O{sub 3}, where the composition range of 0≤y≤0.20 was examined for x=0.2 and 0.25. The highest conductivity, 1.85×10{sup −3} S cm{sup −1} at 250 °C, was obtained for (Li{sub 0.25}Sr{sub 0.625}☐{sub 0.125})(Ga{sub 0.25}Ta{sub 0.75})O{sub 3} (x=0.25, y=0.125). Enhanced ionic conductivities were achieved by the introduction of vacancies at the A-sites. - Graphical abstract: Novel lithium-conducting oxides with the cubic perovskite structure (Li{sub x}Sr{sub 1−x−y}☐{sub y})(Ga{sub [(1−x)/2]−y}Ta{sub [(1+x)/2]+y})O{sub 3} provide a specific solid-solution region with various x and y values, exhibiting the highest ionic conductivity (1.85 S cm{sup −1} at 250 °C) for (Li{sub 0.25}Sr{sub 0.625}☐{sub 0.125})(Ga{sub 0.25}Ta{sub 0.75})O{sub 3} (x=0.25, y=0.125 in (Li{sub x}Sr{sub 1−x−y}☐{sub y})(Ga{sub [(1−x)/2]−y}Ta{sub [(1+x)/2]+y})O{sub 3}). The vacancies (☐) introduced into the A-sites contribute to the enhancement of lithium diffusion in the perovskite structure because of the enlargement of the bottleneck size and suppression of the interaction between lithium and oxygen. - Highlights: • The perovskite-structured novel Li

  5. Syntheses, structures, and ionic conductivities of perovskite-structured lithium–strontium–aluminum/gallium–tantalum-oxides

    International Nuclear Information System (INIS)

    The ionic conductivities of new perovskite-structured lithium–strontium–aluminum/gallium–tantalum oxides were investigated. Solid solutions of the new perovskite oxides, (LixSr1−x)(Al(1−x)/2Ta(1+x)/2)O3 and (LixSr1−x)(Ga(1−x)/2Ta(1+x)/2)O3, were synthesized using a ball-milled-assisted solid-state method. The partial substitution of the smaller Ga+3 for Ta+5 resulted in new compositions, the structures of which were determined by neutron diffraction measurements using a cubic perovskite structural model with the Pm−3m space group. Vacancies were introduced into the Sr(Li) sites by the formation of solid solutions with compositions (LixSr1−x−y☐y)(Ga[(1−x)/2]−yTa[(1+x)/2]+y)O3, where the composition range of 0≤y≤0.20 was examined for x=0.2 and 0.25. The highest conductivity, 1.85×10−3 S cm−1 at 250 °C, was obtained for (Li0.25Sr0.625☐0.125)(Ga0.25Ta0.75)O3 (x=0.25, y=0.125). Enhanced ionic conductivities were achieved by the introduction of vacancies at the A-sites. - Graphical abstract: Novel lithium-conducting oxides with the cubic perovskite structure (LixSr1−x−y☐y)(Ga[(1−x)/2]−yTa[(1+x)/2]+y)O3 provide a specific solid-solution region with various x and y values, exhibiting the highest ionic conductivity (1.85 S cm−1 at 250 °C) for (Li0.25Sr0.625☐0.125)(Ga0.25Ta0.75)O3 (x=0.25, y=0.125 in (LixSr1−x−y☐y)(Ga[(1−x)/2]−yTa[(1+x)/2]+y)O3). The vacancies (☐) introduced into the A-sites contribute to the enhancement of lithium diffusion in the perovskite structure because of the enlargement of the bottleneck size and suppression of the interaction between lithium and oxygen. - Highlights: • The perovskite-structured novel Li–Sr–Al/Ga–Ta oxides were investigated. • The Ga cation offers a larger bottleneck by increasing the B−O bond length. • The greater conductivity was observed upon Ga-containing perovskite. • The ionic conductivity was improved by the introduction of vacancies into A-site

  6. Facile template-free synthesis of pine needle-like Pd micro/nano-leaves and their associated electro-catalytic activities toward oxidation of formic acid

    Directory of Open Access Journals (Sweden)

    Wang Chuanyi

    2011-01-01

    Full Text Available Abstract Pine needle-like Pd micro/nano-leaves have been synthesized by a facile, template-free electrochemical method. As-synthesized Pd micro/nano-leaves were directly electrodeposited on an indium tin oxide substrate in the presence of 1.0 mM H2PdCl4 + 0.33 M H3PO4. The formation processes of Pd micro/nano-leaves were revealed by scanning electron microscope, and further characterized by X-ray diffraction and electrochemical analysis. Compared to conventional Pd nanoparticles, as-prepared Pd micro/nano-leaves exhibit superior electrocatalytic activities for the formic acid oxidation.

  7. Comparison of the kinetic laws of the dissolution of bauxite and aluminum and iron(III) oxides and hydroxides in hydrochloric acid

    Science.gov (United States)

    Gololobova, E. G.; Gorichev, I. G.; Lainer, Yu. A.; Kozlov, K. V.

    2013-07-01

    The influence of the temperature and concentration of a hydrochloric acid solution on the dissolution kinetics of aluminum and iron(III) oxides and hydroxides and a natural sample of aluminum-containing raw materials, bauxite, is studied. The rate W of the transition of iron(III) ions from bauxite is higher than the rate of aluminum ion transition. The dependence of the fraction of a dissolved solid phase on time τ of dissolution of the oxides and hydroxides is determined, α = 1 — exp(- Asinh( Wτ)). The solubility of iron(III) chloride increases and that of aluminum chloride decreases as the HCl concentration increases. An empirical equation is proposed for the description of the dependence of the process rate on a series of parameters,.

  8. Effecting Factors on Thickness of Oxide Aluminum Membrane%多孔阳极氧化铝膜厚度影响因素

    Institute of Scientific and Technical Information of China (English)

    王晓燕; 翟秀静; 张延安; 符岩; 郑双

    2011-01-01

    以H2SO4为电解液对高纯铝箔进行阳极氧化,用涡流测厚仪分析制备工艺参数对多孔氧化铝膜厚度的影响.结果表明,在一定电解液浓度及电解电压下,氧化铝膜厚度随电解液浓度及电解电压的增加而增大,但过高的电解液浓度及电解电压均会造成氧化铝膜的快速击穿.氧化铝膜厚度随电解时间的增加而增大,但初期的增长速度较快,后期随电解时间的增加变化缓慢.在一定温度范围内氧化铝膜的厚度随温度的升高而增加.%High-pure aluminum foil is oxidized in anodic with H2SO4 as electrolyte. The effect of the technological parameters on thickness of oxide aluminum membrane is investigated by using eddy current sensor thickness. The results show that the thickness of oxide aluminum membrane is increased with the increase of electrolyte concentration and voltage, but the exorbitant electrolyte concentration and electrolysis voltage are prone to rapid breakdown of aluminum foil. The thickness of oxide aluminum membrane is increased with the increase of the electrolysis time, however the growth speed of oxide aluminum membrane thickness is firstly fast and then becomes slow. Within a certain range of temperature, the thickness of oxide aluminum membrane is increased with the increase of the electrolysis temperature.

  9. Chemical and structural analysis of solvothermal synthesized tungsten oxide nanotube without template and its hydrogen sensitive property

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Taisheng; Zhang, Yue, E-mail: zhangy@buaa.edu.cn; Li, Chen

    2014-01-25

    Graphical abstract: Imaged models of formation of nanotube during crystal growth: (a) precursor react with each other; (b) the crystal plane bended as crystallization; (c) the nanotube formed finally. Highlights: • The WO{sub 3} naonotube was prepared by solvothermal method without any addition. • The steric effect and the nucleation and growth mechanism resulted in the nanotube. • The nanotube film surface showed high oxygen vacancies. • The nanotube film showed diffusion dominated sensitivity. -- Abstract: Tungsten oxide nanotubes were synthesized by solvothermal process without template. The steric effect and the concentration of WCl{sub 6} are the dominant factors for the formation mechanism of the nanotube. The steric effect was experimentally and systematically studied with solvents including ethanol, isopropanol, n-propanol and butylalcohol, which have different molecular configuration and length, while the effect of concentration was investigated by characterizing the nanostructured productions. The samples have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The surface chemistry of the nanotube is characterized by X-ray photoelectron spectroscopy (XPS). The results indicated that the solvents species and WCl{sub 6} concentration obviously diversified the morphologies of the products; the nanotubes synthesized with isopropanol composed of W{sub 18}O{sub 49} phase; the crystal defects (O atom vacancy) formed during rapid crystallization could be modified by heat treatment. The DC electrical response of the nanotube thin film to hydrogen was measured the temperature range from 200 °C to 300 °C, which indicated a decline in electrical resistance with good sensitivity, and showed the mechanism that the reaction limited process works at low temperature, whereas the diffusion limited process works at higher temperature.

  10. Structural, Optical, and Dielectric Properties of Aluminum Oxide Nanofibers Synthesized by a Lower-Temperature Sol-Gel Approach

    Science.gov (United States)

    Riaz, Saira; Sajid-ur-Rehman; Abutalib, Mymona; Naseem, Shahzad

    2016-10-01

    Alumina (Al2O3) is the most versatile and important ceramic material, having applications in various fields including electronic devices. It is stable at high temperatures and is chemically inert. The sol-gel method, a relatively lower-temperature technique, has been used to synthesize aluminum oxide nanofibers. The molarity of the sol concentration was varied as 0.7 M, 0.8 M, 0.9 M, 1.0 M, and 1.1 M. The structural, optical, and dielectric properties of the as-synthesized nanofibers were characterized. x-ray diffraction (XRD) analysis results confirmed formation of α-Al2O3 phase of aluminum oxide, notably without any heat treatment or use of water as solvent. The crystallite size and unit cell volume of the nanofibers increased as the sol concentration was increased to 0.9 M, but further increase in sol concentration resulted in reduction of crystallite size and increase in dislocations. Scanning electron microscopy (SEM) results revealed uniform distribution of nanofibers (˜25 nm to 30 nm) under all conditions. Nanofibers prepared using sol concentration of 0.9 M showed high transmission (˜89%) in the visible and infrared regions. The energy bandgap varied from 3.69 eV to 4.1 eV with the variation in molar concentration. Lower bandgap correlated with defect-induced states in the bandgap. The high refractive index is indicative of high density of aluminum oxide nanofibers. High grain-boundary resistance (1.455 MΩ) and high dielectric constant (˜15.76) along with low tangent loss were observed at molar concentration of 0.9 M.

  11. Structural, Optical, and Dielectric Properties of Aluminum Oxide Nanofibers Synthesized by a Lower-Temperature Sol-Gel Approach

    Science.gov (United States)

    Riaz, Saira; Sajid-ur-Rehman; Abutalib, Mymona; Naseem, Shahzad

    2016-07-01

    Alumina (Al2O3) is the most versatile and important ceramic material, having applications in various fields including electronic devices. It is stable at high temperatures and is chemically inert. The sol-gel method, a relatively lower-temperature technique, has been used to synthesize aluminum oxide nanofibers. The molarity of the sol concentration was varied as 0.7 M, 0.8 M, 0.9 M, 1.0 M, and 1.1 M. The structural, optical, and dielectric properties of the as-synthesized nanofibers were characterized. x-ray diffraction (XRD) analysis results confirmed formation of α-Al2O3 phase of aluminum oxide, notably without any heat treatment or use of water as solvent. The crystallite size and unit cell volume of the nanofibers increased as the sol concentration was increased to 0.9 M, but further increase in sol concentration resulted in reduction of crystallite size and increase in dislocations. Scanning electron microscopy (SEM) results revealed uniform distribution of nanofibers (˜25 nm to 30 nm) under all conditions. Nanofibers prepared using sol concentration of 0.9 M showed high transmission (˜89%) in the visible and infrared regions. The energy bandgap varied from 3.69 eV to 4.1 eV with the variation in molar concentration. Lower bandgap correlated with defect-induced states in the bandgap. The high refractive index is indicative of high density of aluminum oxide nanofibers. High grain-boundary resistance (1.455 MΩ) and high dielectric constant (˜15.76) along with low tangent loss were observed at molar concentration of 0.9 M.

  12. Hybrid aluminum and indium conducting filaments for nonpolar resistive switching of Al/AlOx/indium tin oxide flexible device

    Science.gov (United States)

    Yuan, Fang; Wang, Jer-Chyi; Zhang, Zhigang; Ye, Yu-Ren; Pan, Liyang; Xu, Jun; Lai, Chao-Sung

    2014-02-01

    The nonpolar resistive switching characteristics of an Al/AlOx/indium tin oxide (ITO) device on a plastic flexible substrate are investigated. By analyzing the electron diffraction spectroscopy results and thermal coefficient of resistivity, it is discovered that the formation of aluminum and indium conducting filaments in AlOx film strongly depends on the polarity of the applied voltage. The metal ions arising from the Al and ITO electrodes respectively govern the resistive switching in corresponding operation polarity. After 104 times of mechanical bending, the device can perform satisfactorily in terms of resistance distribution, read sequence of high and low resistive states, and thermal retention properties.

  13. Gas-Phase Partial Oxidation of Lignin to Carboxylic Acids over Vanadium Pyrophosphate and Aluminum-Vanadium-Molybdenum.

    Science.gov (United States)

    Lotfi, Samira; Boffito, Daria C; Patience, Gregory S

    2015-10-26

    Lignin is a complex polymer that is a potential feedstock for aromatic compounds and carboxylic acids by cleaving the β-O-4 and 5-5' linkages. In this work, a syringe pump atomizes an alkaline solution of lignin into a catalytic fluidized bed operating above 600 K. The vanadium heterogeneous catalysts convert all the lignin into carboxylic acids (up to 25 % selectivity), coke, carbon oxides, and hydrogen. Aluminum-vanadium-molybdenum mostly produced lactic acid (together with formic acid, acrylic acid, and maleic anhydride), whereas the vanadium pyrophosphate catalyst produced more maleic anhydride. PMID:26361086

  14. Highly flexible transparent thin film heaters based on silver nanowires and aluminum zinc oxides

    Energy Technology Data Exchange (ETDEWEB)

    Cheong, Hahn-Gil; Kim, Jin-Hoon; Song, Jun-Hyuk; Jeong, Unyong; Park, Jin-Woo, E-mail: jwpark09@yonsei.ac.kr

    2015-08-31

    In this work, we developed highly flexible transparent film heaters (f-TFHs) composed of Ag nanowire networks (AgNWs) and aluminum zinc oxide (AZO). Uniform AgNWs were roll-to-roll coated on polyethylene terephthalate (PET) substrates using the Mayer rod method, and AZO was sputter-deposited atop the AgNWs at room temperature. The sheet resistance (R{sub s}) and transparency (T{sub opt}) of the AZO-coated AgNWs changed only slightly compared with the uncoated AgNWs. AZO is thermally less conductive than the heat pipes, but increases the thermal efficiency of the heaters blocking the heat convection through the air. Based on Joule heating, a higher average film temperature (T{sub ave}) is attained at a fixed electric potential drop between electrodes (ϕ) as the R{sub s} of the film decreases. Our experimental results revealed that T{sub ave} of the hybrid f-TFH is higher than AgNWs when the ratio of the area coverage of AgNWs to AZO is over a certain value. When a ϕ as low as 3 V/cm was applied to 5 cm × 5 cm f-TFHs, the maximum temperature of the hybrid film was over 100 °C, which is greater than that of AgNWs by more than 30 °C. Furthermore, uniform heating throughout the surfaces is achieved in the hybrid films while heating begins in small areas where densities of the nanowires (NWs) are the highest in the bare network. The non-uniform heating decreases the lifetime of f-TFHs by forming hot spots. Cyclic bending test results indicated that the hybrid films were as flexible as the AgNWs, and the R{sub s} of the hybrid films changes only slightly until 5000 cycles. Combined with the high-throughput coating technology presented here, the hybrid films will provide a robust and scalable strategy for large-area f-TFHs with highly enhanced performance. - Highlights: • We developed highly efficient flexible thin film heaters based on Ag nanowires and AZO composites. • In the composite, AZO plays an important role as an insulation blanket to block heat loss to

  15. Soft template strategy to synthesize iron oxide-titania yolk-shell nanoparticles as high-performance anode materials for lithium-ion battery applications.

    Science.gov (United States)

    Lim, Joohyun; Um, Ji Hyun; Ahn, Jihoon; Yu, Seung-Ho; Sung, Yung-Eun; Lee, Jin-Kyu

    2015-05-18

    Yolk-shell-structured nanoparticles with iron oxide core, void, and a titania shell configuration are prepared by a simple soft template method and used as the anode material for lithium ion batteries. The iron oxide-titania yolk-shell nanoparticles (IO@void@TNPs) exhibit a higher and more stable capacity than simply mixed nanoparticles of iron oxide and hollow titania because of the unique structure obtained by the perfect separation between iron oxide nanoparticles, in combination with the adequate internal void space provided by stable titania shells. Moreover, the structural effect of IO@void@TNPs clearly demonstrates that the capacity retention value after 50 cycles is approximately 4 times that for IONPs under harsh operating conditions, that is, when the temperature is increased to 80 °C.

  16. Modeling the Normal Spectral Emissivity of Aluminum 1060 at 800-910 K During the Growth of Oxide Layer

    Science.gov (United States)

    Shi, Deheng; Zou, Fenghui; Zhu, Zunlue; Sun, Jinfeng

    2015-04-01

    This work strives to model the normal spectral emissivity of aluminum 1060 during the growth of oxide layer in air over the temperatures ranging from 800 to 910 K. For this reason, the normal spectral emissivity of aluminum 1060 has been measured over a 6 h heating period at a definite temperature. In our experiment, the radiance coming from the specimen is received by an InGaAs photodiode detector, which works at 1.5 μm with the bandwidth of 20 nm. The temperature of specimen surface is measured by averaging the two platinum-rhodium thermocouples, which are symmetrically welded in the front surface of specimen near the measuring area viewed by the detector. The strong oscillations of normal spectral emissivity have been observed and discussed, which are affirmed to be connected with the thickness of oxide layer on the specimen surface, and originate from the interference effect between the radiation coming from the oxide layer on the specimen surface and the radiation stemming from the substrate. The uncertainty of normal spectral emissivity contributed only by the surface oxidization is about 4.6-10.6%, and the corresponding uncertainty of temperature contributed only by the surface oxidization is about 3.5-8.4 K. The analytical model between the normal spectral emissivity and the heating time is evaluated at a definite temperature. A simple functional form with the exponential and logarithmic functions can be employed to reproduce well the variation of normal spectral emissivity with the heating time at a definite temperature, including the reproduction of strong oscillations.

  17. Pulmonary fibrosis in aluminum oxide workers. Investigation of nine workers, with pathologic examination and microanalysis in three of them

    International Nuclear Information System (INIS)

    Epidemiologic surveys have indicated an excess of nonmalignant respiratory disease in workers exposed to aluminum oxide (Al2O3) during abrasives production. However, clinical, roentgenographic, histologic, and microanalytic description of these workers are lacking. This is a report of nine Al2O3-exposed workers with abnormal chest roentgenograms (profusion greater than or equal to 1/0, ILO/UC) from a plant engaged in the production of Al2O3 abrasives from alundum ore. Mean duration of exposure was 25 yr, and time since first exposure was 28 yr. in a subgroup of three, the severity of symptoms, reduction in the forced vital capacity (67% predicted) and diffusing capacity (51% predicted), and progressive roentgenographic changes (profusion greater than or equal to 2/2) prompted open lung biopsy. Lung tissue was analyzed by scanning electron microscopy and electron microprobe analysis. In each of the three biopsies, interstitial fibrosis with honeycombing was seen on routine section. In one biopsy, silica and asbestos fiber counts were at the low end of the range seen with silicosis and asbestosis; however, the absence of asbestos bodies and silicotic nodules suggested that the fibrosis was due to another cause. Metals occurred in amounts several orders of magnitude above background, and the majority was aluminum as Al2O3 and aluminum alloys. The findings in these nine workers suggests a common exposure as the possible cause. The nonspecific pathologic findings, absence of asbestos bodies and silicotic nodules, and the striking number of aluminum-containing particles suggest that Al2O3 is that common exposure. The possibility of mixed dust fibrosis should also be considered

  18. Quasi-hexagonal vortex-pinning lattice using anodized aluminum oxide nanotemplates

    DEFF Research Database (Denmark)

    Hallet, X.; Mátéfi-Tempfli, M.; Michotte, S.;

    2009-01-01

    The bottom barrier layer of well-ordered nanoporous alumina membranes reveals a previously unexploited nanostructured template surface consisting of a triangular lattice of hemispherical nanoscale bumps. Quasi-hexagonal vortex-pinning lattice arrays are created in superconducting Nb films deposit...

  19. Laser Melt Injection in Aluminum Alloys : On the Role of the Oxide Skin

    NARCIS (Netherlands)

    Vreeling, J.A.; Ocelík, V.; Pei, Y.T.; Agterveld, D.T.L. van; Hosson, J.Th.M. De

    2000-01-01

    In this paper the method of laser melt injection of SiC particles into an aluminum substrate is investigated both experimentally and theoretically. An extremely small operational parameter window was found for successful injection processing. It is shown that the final injection depth of the particl

  20. Comprehensive study and design of scaled metal/high-k/Ge gate stacks with ultrathin aluminum oxide interlayers

    Energy Technology Data Exchange (ETDEWEB)

    Asahara, Ryohei; Hideshima, Iori; Oka, Hiroshi; Minoura, Yuya; Hosoi, Takuji, E-mail: hosoi@mls.eng.osaka-u.ac.jp; Shimura, Takayoshi; Watanabe, Heiji [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Ogawa, Shingo [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Toray Research Center Inc., 3-3-7 Sonoyama, Otsu, Shiga 520-8567 (Japan); Yoshigoe, Akitaka; Teraoka, Yuden [Japan Atomic Energy Agency, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)

    2015-06-08

    Advanced metal/high-k/Ge gate stacks with a sub-nm equivalent oxide thickness (EOT) and improved interface properties were demonstrated by controlling interface reactions using ultrathin aluminum oxide (AlO{sub x}) interlayers. A step-by-step in situ procedure by deposition of AlO{sub x} and hafnium oxide (HfO{sub x}) layers on Ge and subsequent plasma oxidation was conducted to fabricate Pt/HfO{sub 2}/AlO{sub x}/GeO{sub x}/Ge stacked structures. Comprehensive study by means of physical and electrical characterizations revealed distinct impacts of AlO{sub x} interlayers, plasma oxidation, and metal electrodes serving as capping layers on EOT scaling, improved interface quality, and thermal stability of the stacks. Aggressive EOT scaling down to 0.56 nm and very low interface state density of 2.4 × 10{sup 11 }cm{sup −2}eV{sup −1} with a sub-nm EOT and sufficient thermal stability were achieved by systematic process optimization.

  1. Mesoporous zirconium titanium oxides. Part 3. Synthesis and adsorption properties of unfunctionalized and phosphonate-functionalized hierarchical polyacrylonitrile-F-127-templated beads.

    Science.gov (United States)

    Sizgek, G Devlet; Griffith, Christopher S; Sizgek, Erden; Luca, Vittorio

    2009-10-01

    A method is presented for the preparation of zirconium titanate mixed oxides in bead form having hierarchical pore structure. This method entailed the use of both preformed polyacrylonitrile (PAN) polymer beads and surfactants as templates. The templates were removed by calcination at temperatures below about 500 degrees C, resulting in mixed oxide beads with trimodal pore size distributions and interconnected pores. The pore size distributions as determined using nitrogen adsorption-desorption showed clear maxima at 4.5 and 45 nm length scales and also clear evidence of microporosity. The macroporous framework morphology was a replica of the PAN beads with radial structure. The mesoporous framework possessed wormhole-like pores with pore size of about 6 nm that was consistent with the F-127 triblock copolymer template used. The mixed oxide beads exhibited surface areas of 215 and 185 m2/g after calcination at 500 and 600 degrees C. Thermal stability up to 650 degrees C is unprecedented for bulk systems. The adsorption properties were characterized using uranyl as the target cation and the mass transport in the beads with the present hierarchical architectures has been shown to be exceptional. The beads were functionalized with 4-amino,1-hydroxy,1,1-bis-phosphonic acid (HABDP) and amino-tris-methylene phosphonic acid (ATMP) and the adsorption properties for the extraction of uranyl sulfate complexes from acidic solution examined. Of the two molecules investigated, ATMP functionalization resulted in the best extraction efficiency with equilibrium uptake of about 90% of uranium available in solution between pH 1 and 2. The beads could potentially be utilized as catalysts, catalyst supports, adsorbents, and separation materials. PMID:19746937

  2. Facile template-free synthesis of pine needle-like Pd micro/nano-leaves and their associated electro-catalytic activities toward oxidation of formic acid

    OpenAIRE

    Wang Chuanyi; Xu Jingkun; Zhou Rong; Zhou Weiqiang; Zhang Hongmei; Du Yukou; Yang Ping

    2011-01-01

    Abstract Pine needle-like Pd micro/nano-leaves have been synthesized by a facile, template-free electrochemical method. As-synthesized Pd micro/nano-leaves were directly electrodeposited on an indium tin oxide substrate in the presence of 1.0 mM H2PdCl4 + 0.33 M H3PO4. The formation processes of Pd micro/nano-leaves were revealed by scanning electron microscope, and further characterized by X-ray diffraction and electrochemical analysis. Compared to conventional Pd nanoparticles, as-prepared ...

  3. Equation of state of aluminum-iron oxide-epoxy composite

    Science.gov (United States)

    Jordan, Jennifer L.; Ferranti, Louis; Austin, Ryan A.; Dick, Richard D.; Foley, Jason R.; Thadhani, Naresh N.; McDowell, David L.; Benson, David J.

    2007-05-01

    We report on the measurements of the shock equation of state (Hugoniot) of an Al/Fe2O3/epoxy composite, prepared by epoxy cast curing of powder mixtures. Explosive loading, with Baratol, trinitrotoluene (TNT), and Octol, was used for performing experiments at higher pressures, in which case shock velocities were measured in the samples and aluminum, copper, or polymethyl methacrylate (PMMA) donor material, using piezoelectric pins. The explosive loading of the metal donors (aluminum and copper) will be discussed. Gas gun experiments provide complementary lower pressure data in which piezoelectric polyvinylidene fluoride (PVDF) stress gauges were used to measure the input and propagated stress wave profiles in the sample and the corresponding shock propagation velocity. The results of the Hugoniot equation of state are compared with mesoscale finite-element simulations, which show good agreement.

  4. Structure and formation mechanism of rolled-in oxide areas on aluminum lithographic printing sheets

    International Nuclear Information System (INIS)

    The subsurface area introduced during rolling on the 1100 aluminum alloy series alters its surface properties, which makes it more susceptible to corrosion. A combination of different transmission electron microscopy techniques is employed to observe the orientation of small grain structures and the distribution elements in the subsurface layer. This approach provided valuable insight into the formation mechanism of the layer and the phenomena taking place during rolling.

  5. Salicylic acid alleviates aluminum toxicity in rice seedlings better than magnesium and calcium by reducing aluminum uptake, suppressing oxidative damage and increasing antioxidative defense.

    Science.gov (United States)

    Pandey, Poonam; Srivastava, Rajneesh Kumar; Dubey, R S

    2013-05-01

    Aluminum toxicity is a major constraint to crop production in acid soils. The present study was undertaken to examine the comparative ameliorating effects of salicylic acid, Ca and Mg on Al toxicity in rice (Oryza sativa L.) seedlings grown in hydroponics. Al treatment (0.5 mM AlCl3) caused decrease in plant vigour, loss of root plasma membrane integrity, increased contents of O 2 (∙-) , H2O2, lipid peroxidation, protein carbonyls and decline in the level of protein thiol. Al treatment caused significant changes in activity of antioxidative enzymes in rice seedlings. Exogenously added salicylic acid (60 μM), Ca (1 mM) and Mg (0.25 mM) significantly alleviated Al toxicity effects in the seedlings marked by restoration of growth, suppression of Al uptake, restoration of root plasma membrane integrity and decline in O 2 (∙-) , H2O2, lipid peroxidation and protein carbonyl contents. Salicylic acid, Ca and Mg suppressed Al-induced increase in SOD, GPX and APX activities while it elevated Al-induced decline in CAT activity. By histochemical staining of O 2 (∙-) using NBT and H2O2 using DAB, it was further confirmed that added salicylic acid, Ca or Mg decreased Al-induced accumulation of O 2 (∙-) and H2O2 in the leaf tissues. Results indicate that exogenously added salicylic acid, Ca or Mg alleviates Al toxicity in rice seedlings by suppressing Al uptake, restoring root membrane integrity, reducing ROS level and ROS induced oxidative damage and regulating the level of antioxidative enzyme activities. Further salicylic appears to be superior to Mg and Ca in alleviating Al toxicity effects in rice plants.

  6. The resistive switching memory of CoFe2O4 thin film using nanoporous alumina template

    OpenAIRE

    Jiang, Changjun; Wu, Lei; Wei, WenWen; Dong, Chunhui; Yao, Jinli

    2014-01-01

    A novel conductive process for resistive random access memory cells is investigated based on nanoporous anodized aluminum oxide template. Bipolar resistive switching characteristic is clearly observed in CoFe2O4 thin film. Stable and repeatable resistive switching behavior is acquired at the same time. On the basis of conductive filament model, possible generation mechanisms for the resistive switching behaviors are discussed intensively. Besides, the magnetic properties of samples (before an...

  7. Entropic nature of the adsorption of sodium dodecylbenzenesulfonate on nanoparticles of aluminum and iron oxides in aqueous medium

    Science.gov (United States)

    Mansurov, R. R.; Safronov, A. P.; Lakiza, N. V.

    2016-06-01

    The adsorption of anionic surfactant sodium dodecylbenzenesulfonate (SDBS) from aqueous solution on the hydrophilic surfaces of aluminum oxide and iron oxide nanoparticles is studied via UV spectrophotometry, electrophoretic light scattering, and isothermal microcalorimetry. It is shown that the isotherms of the adsorption of SDBS on the surfaces of both oxides in the area of concentrations up to 0.6 mmol/L is linear. It is found that the positive zeta potential of the surfaces of the particles falls to zero and shifts toward the range of negative values due to adsorption. The adsorption of SDBS is characterized by positive enthalpy values over the investigated range of concentrations, while the loss of energy during adsorption indicates it is of an entropic nature. It is concluded that the probable cause of the increase in entropy is the dehydration of SDBS molecules during on surface adsorption. The obtained results are discussed in terms of the formation of hemimicelles of surfactant on the hydrophilic surfaces of metal oxide nanoparticles in an aqueous medium.

  8. Template synthesis and characterization of molybdenum disulfide nanotubules

    International Nuclear Information System (INIS)

    Graphical abstract: The image is a SEM image of branched MoS2 nanotubes, which are prepared in AAO templates. It is obvious to observe the branch of MoS2 nanotubes (labeled by arrows), and it reflects the microcosmic morphologies of pores in templates. Highlights: → Large quantities of hollow MoS2 tubules. → Explanation for the formation of branched shape. → Explanation for the morphology of bamboo-like structure. -- Abstract: Molybdenum disulfide nanotubules were prepared by thermal decomposition of ammonium thiomolybdate ((NH4)2MoS4) precursors on anodized aluminum oxide template. Large quantities of hollow MoS2 nanotubules with the bamboo-like structure were obtained. The morphology and structures of MoS2 tubules were characterized by scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy, electron diffraction and optical absorption spectroscopy. MoS2 nanotubules completely reflected the three-dimensional structure of nanopores in template. The properties of Mo-S chemical bonds in lattice structure and the wetting state between porous surface and precursor have a great effect on the formation of sections in nanotubules, the ridges in the nanopores also play a very special role of this formation.

  9. Density control and wettability enhancement by functionalizing carbon nanotubes with nickel oxide in aluminum-carbon nanotube system.

    Science.gov (United States)

    Kim, Tae-Hoon; Park, Min-Ho; Song, Kwan-Woo; Bae, Jee-Hwan; Lee, Jae-Wook; Lee, Choong Do; Yang, Cheol-Woong

    2013-11-01

    Excellent mechanical properties of carbon nanotubes (CNTs) make them ideal reinforcements for synthesizing light weight, high strength metal matrix composite. Aluminum is attractive matrix due to its light weight and Al/CNT composites are promising materials for various industrial applications. Powder metallurgy and casting techniques are normally used for bulk fabrications of composites. Casting process which can mass-produce delicate product is more suitable than existing powder metallurgy in view point of application in industries. In CNT-metal matrix composites, however, composite bulk fabrication has been limited because of the large density gap and poor wettability between the metal and CNTs. This study suggests a method for alleviating such problems. It was found that the wettability between aluminum and CNT could be enhanced by functionalizing the CNTs with nickel oxide. This functionalization of CNTs with heavier element also reduces the density gap between the matrix and reinforcements. It is suggested that this method could possibly be used in a casting process to enable mass fabrication of CNT-metal matrix composites.

  10. Oxidative removal of acetaminophen using zero valent aluminum-acid system:Efficacy, influencing factors, and reaction mechanism

    Institute of Scientific and Technical Information of China (English)

    Honghua Zhang; Beipei Cao; Wanpeng Liu; Kunde Lin; Jun Feng

    2012-01-01

    Commercial available zero valent aluminum under air-equilibrated acidic conditions (ZVA1/H+/air system) demonstrated an excellent capacity to remove aqueous organic compounds.Acetaminophen (ACTM),the active ingredient of the over-the-counter drug Tylenol(R),is widely present in the aquatic environment and therefore the treatment of ACTM-contaminated water calls for further research.Herein we investigated the oxidative removal of ACTM by ZVAl/H+/air system and the reaction mechanism.In acidic solutions (pH < 3.5),ZVAl displayed an excellent capacity to remove ACTM.More than 99% of ACTM was eliminated within 16 hr in pH 1.5 reaction solutions initially containing 2.0 g/L aluminum and 2.0 mg/L ACTM at 25 ± 1℃.Higher temperature and lower pH facilitated ACTM removal.The addition of different iron species Fe0,Fe2+ and Fe3+ into ZVAl/H+/air system dramatically accelerated the reaction likely due to the enhancing transformation of H2O2 to HO·via Fenton's reaction.Furthermore,the primary intermediate h.ydroquinone and the anions formate,acetate and nitrate,were identified and a possible reaction scheme was proposed.This work suggested that ZVA1/H+/air system may be potentially employed to treat ACTM-contaminated water.

  11. Analysis of Intermetallic Phases Formed on Surface Vapor Oxidized H13 Hot Work Steels in Molten Aluminum

    Institute of Scientific and Technical Information of China (English)

    WANGRong; WUXiao-chun; MINYong-an

    2004-01-01

    In this paper, the author dipped surface vapor oxidized H13 steel specimens into 700℃ molten aluminum liquid for a certain period of time. Analyze the intermetallic phases formed on the H 13 samples surface with optical microscope and X-ray diffraction method. The observation of immersion test sample's cross-section shows that Fe304 film will protect die substrate from molten aluminum erosion. The identification of the intermetallic phases reveals that they consist of 2 parts, which is named as the composite layer and the compact layer. Further investigations are made in order to know the phase constituents of the 2 layers, they are Al8Fe2Si (outer composite layer), (AlCuMg) and Al5Fe2 (compact layer), respectively. The experimental results show that on the same specimen, a convex surface with bigger radius of curvature is more likely to be molten and the melting loss speed is also faster than a flat and smooth surface. The thickness of compact layer on a smooth surface is much bigger than that of the convex surface. Therefore, the author supposes the compact layer is favorable in stabilizing the die surface material from further melting loss, as their formation on the die surface, the melting loss speed will decrease.

  12. Analysis of Intermetallic Phases Formed on Surface Vapor Oxidized H13 Hot Work Steels in Molten Aluminum

    Institute of Scientific and Technical Information of China (English)

    WANG Rong; WU Xiao-chun; MIN Yong-an

    2004-01-01

    In this paper, the author dipped surface vapor oxidized H13 steel specimens into 700℃ molten aluminum liquid for a certain period of time. Analyze the intermetallic phases formed on the H13 samples surface with optical microscope and X-ray diffraction method. The observation of immersion test sample's cross-section shows that Fe3O4 film will protect die substrate from molten aluminum erosion. The identification of the intermetallic phases reveals that they consist of 2parts, which is named as the composite layer and the compact layer. Further investigations are made in order to know the phase constituents of the 2 layers, they are Al8Fe2Si (outer composite layer), (AlCuMg) and Al5Fe2 (compact layer),respectively. The experimental results show that on the same specimen, a convex surface with bigger radius of curvature is more likely to be molten and the melting loss speed is also faster than a flat and smooth surface. The thickness of compact layer on a smooth surface is much bigger than that of the convex surface. Therefore, the author supposes the compact layer is favorable in stabilizing the die surface material from further melting loss, as their formation on the die surface, the melting loss speed will decrease.

  13. The influence of atmospheric species on the degradation of aluminum doped zinc oxide and Cu(In,Ga)Se2 solar cells

    NARCIS (Netherlands)

    Theelen, M.J.; Foster, C.; Dasgupta, S.; Vroon, Z.A.E.P.; Barreau, N.; Zeman, M.

    2014-01-01

    Aluminum doped zinc oxide (ZnO:Al) layers were exposed to the atmospheric gases carbondioxide (CO2), oxygen (O2), nitrogen (N2) and air as well as liquid H2O purged with these gases, in order to investigate the chemical degradation behavior of these layers. The samples were analyzed by electrical, c

  14. Physical and chemical degradation behavior of sputtered aluminum doped zinc oxide layers for Cu(In,Ga)Se2 solar cells

    NARCIS (Netherlands)

    Theelen, M.; Boumans, T.; Stegeman, F.; Colberts, F.; Illiberi, A.; Berkum, J. van; Barreau, N.; Vroon, Z.; Zeman, M.

    2014-01-01

    Sputtered aluminum doped zinc oxide (ZnO:Al) layers on borosilicate glass were exposed to damp heat (85 C/85% relative humidity) for 2876 h to accelerate the physical and chemical degradation behavior. The ZnO:Al samples were characterized by electrical, compositional and optical measurements before

  15. Synthesis of hierarchical NiCo2O4 hollow nanorods via sacrificial-template accelerate hydrolysis for electrochemical glucose oxidation.

    Science.gov (United States)

    Yang, Jiao; Cho, Misuk; Lee, Youngkwan

    2016-01-15

    Hierarchical NiCo2O4 hollow nanorods (HR) were directly grown on stainless steel via a sacrificial template accelerated hydrolysis and post calcination using ZnO nanorod as a template. The composition of the NiCo2O4 HR electrode was determined using X-ray diffraction and X-ray photoelectron spectroscopy. The morphology of the NiCo2O4 HR is comprised of nanoflakes that were characterized with scanning electron microscopy and transmission electron microscopy. The mixed-valence metal oxide and hollow structure provided high chemical reactivity and a large surface area for glucose oxidation in an alkaline solution. Under an optimal applied potential of +0.6 V, the developed NiCo2O4 HR electrode showed a broad detection range of 0.0003–1.0 mM, a sensitivity of 1685.1 μA mM−1 cm−2, and a low detection limit of 0.16 μM. These results represent a significant improvement over both NiO and Co3O4 HR. The developed NiCo2O4 HR electrode not only demonstrated excellent selectivity in the presence of several electro-active species, but also exhibited high stability following a 200 cycles voltammetry test. PMID:26281005

  16. Corrosion resistance of flaky aluminum pigment coated with cerium oxides/hydroxides in chloride and acidic electrolytes

    Science.gov (United States)

    Niroumandrad, S.; Rostami, M.; Ramezanzadeh, B.

    2015-12-01

    The objective of this study was to enhance the corrosion resistance of lamellar aluminum pigment through surface treatment by cerium oxides/hydroxides. The surface composition of the pigments was studied by energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the pigment was evaluated by conventional hydrogen evolution measurements in acidic solution and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. Results showed that the Ce-rich coating composed of Ce2O3 and CeO2 was precipitated on the pigment surface after immersion in the cerium solution. The corrosion resistance of pigment was significantly enhanced after modification with cerium layer.

  17. Simulation study of a highly efficient, high resolution X-ry sensor based on self-organizing aluminum oxide

    CERN Document Server

    Muehlbauer, Joerg; Reims, Nils; Krueger, Peter; Schreiber, Juergen; Mukhurov, Nikolai I; Uhlmann, Norman

    2012-01-01

    State of the art X-ray imaging sensors comprise a trade-off between the achievable efficiency and the spatial resolution. To overcome such limitations, the use of structured and scintillator filled aluminum oxide (AlOx) matrices has been investigated. We used Monte-Carlo (MC) X-ray simulations to determine the X-ray imaging quality of these AlOx matrices. Important factors which influence the behavior of the matrices are: filling factor (surface ratio between channels and 'closed' AlOx), channel diameter, aspect ratio, filling material etc. Therefore we modeled the porous AlOx matrix in several different ways with the MC X-ray simulation tool ROSI [1] and evaluated its properties to investigate the achievable performance at different X-ray spectra, with different filling materials (i.e. scintillators) and varying channel height and pixel readout. In this paper we focus on the quantum efficiency, the spatial resolution and image homogeneity.

  18. Compression Molded Ultra High Molecular Weight Polyethylene-Hydroxyapatite-Aluminum Oxide-Carbon Nanotube Hybrid Composites for Hard Tissue Replacement

    Institute of Scientific and Technical Information of China (English)

    Ankur Gupta; Garima Tripathi; Debrupa Lahiri; Kantesh Balani

    2013-01-01

    Ultra high molecular weight polyethylene (UHMWPE) is widely used for articulating surfaces in total hip and knee replacements.In the present work,UHMWPE based polymer composites were synthesized by synergistic reinforcing of bioactive hydroxyapatite (HA),bioinert aluminum oxide (Al2O3),and carbon nanotubes (CNTs) using compression molding.Phase and microstructural analysis suggests retention of UHMWPE and reinforcing phases in the compression molded composites.Microstructural analysis elicited variation in densification due to the size effect of the reinforcing particles.The hybrid composites exhibited hardness,elastic modulus and toughness comparable to that of UHMWPE.The interfacial effect of reinforcement phases has evinced the effectiveness of Al2O3 over HA and CNT reinforcements,depicting synergistic enhancement in hardness and elastic modulus.Weak interfacial bonding of polymer matrix with HA and CNT requires utilization of coupling agents to achieve enhanced mechanical properties without deteriorating cytocompatible properties.

  19. The effect of oxygen flow rate on refractive index of aluminum oxide film deposited by electron beam evaporation technique

    Directory of Open Access Journals (Sweden)

    R Shakouri

    2016-02-01

    Full Text Available The effects of oxygen flow rate on refractive index of aluminum oxide film have been investigated. The Al2O3 films are deposited by electron beam on glass substrate at different oxygen flow rates. The substrate was heated to reach  and the temperature was constant during the thin film growth. The transmittance spectrum of samples was recorded in the wavelength 400-800 nm.  Then, using the maxima and minima of transmittance the refractive index and the extinction coefficient of samples were determined. It has been found that if we reduce the oxygen flow, while the evaporation rate is kept constant, the refractive index of Al2O3 films increases. On the other hand, reduced oxygen pressure causes the Al2O3 films to have some absorption.

  20. Effects of acetic acid on microstructure and electrochemical properties of nano cerium oxide films coated on AA7020-T6 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    H. Hasannejad; T. Shahrabi; M. Aliofkhazraei

    2009-01-01

    Nano cerium oxide films were applied on AA7020-T6 aluminum alloy and the effects of acetic acid concentration on the microstructure and electrochemical properties of the coated samples were investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD), crack-flee films with well-developed grains were obtained and grain sizes of the films decreased. Elimination of cracks and decreasing grain size of the nano cerium oxide films caused corrosion resistance to increase.

  1. Enhanced adsorptive removal of p-nitrophenol from water by aluminum metal–organic framework/reduced graphene oxide composite

    Science.gov (United States)

    Wu, Zhibin; Yuan, Xingzhong; Zhong, Hua; Wang, Hou; Zeng, Guangming; Chen, Xiaohong; Wang, Hui; Zhang, Lei; Shao, Jianguang

    2016-05-01

    In this study, the composite of aluminum metal–organic framework MIL-68(Al) and reduced graphene oxide (MA/RG) was synthesized via a one–step solvothermal method, and their performances for p–nitrophenol (PNP) adsorption from aqueous solution were systematically investigated. The introduction of reduced graphene oxide (RG) into MIL-68(Al) (MA) significantly changes the morphologies of the MA and increases the surface area. The MA/RG-15% prepared at RG-to-MA mass ratio of 15% shows a PNP uptake rate 64% and 123% higher than MIL-68(Al) and reduced graphene oxide (RG), respectively. The hydrogen bond and π – π dispersion were considered to be the major driving force for the spontaneous and endothermic adsorption process for PNP removal. The adsorption kinetics, which was controlled by film–diffusion and intra–particle diffusion, was greatly influenced by solution pH, ionic strength, temperature and initial PNP concentration. The adsorption kinetics and isotherms can be well delineated using pseudo–second–order and Langmuir equations, respectively. The presence of phenol or isomeric nitrophenols in the solution had minimal influence on PNP adsorption by reusable MA/RG composite.

  2. Sacrificial Template-Based Synthesis of Unified Hollow Porous Palladium Nanospheres for Formic Acid Electro-Oxidation

    OpenAIRE

    Xiaoyu Qiu; Hanyue Zhang; Yuxuan Dai; Fengqi Zhang; Peishan Wu; Pin Wu; Yawen Tang

    2015-01-01

    Large scale syntheses of uniform metal nanoparticles with hollow porous structure have attracted much attention owning to their high surface area, abundant active sites and relatively efficient catalytic activity. Herein, we report a general method to synthesize hollow porous Pd nanospheres (Pd HPNSs) by templating sacrificial SiO2 nanoparticles with the assistance of polyallylamine hydrochloride (PAH) through layer-by-layer self-assembly. The chemically inert PAH is acting as an efficient st...

  3. Preparation of silica-sustained electrospun polyvinylpyrrolidone fibers with uniform mesopores via oxidative removal of template molecules by H2O2 treatment

    International Nuclear Information System (INIS)

    Silica-sustained electrospun PVP fibers with uniform mesopores were synthesized via facile oxidative removal of template molecules by H2O2 extraction. Tetraethyl orthosilicate, polyvinylpyrrolidone (PVP), and triblock poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymer pluronic P123 compose the electrospinning sol to fabricate the silica-sustained PVP hybrid fibers. The effect of different post-treatment methods on the pore size distribution was investigated by calcination and extraction, respectively. Experimental results showed that oxidative removal of structure-directing agent P123 in the hybrid fibers by H2O2 treatment can easily form narrow pore size distribution, and the incorporation of 3D silica skeleton built by hot steam aging facilitated preserving the original cylindrical morphology of fibers. Scanning electron microscopy (SEM), N2 adsorption-desorption isotherm, transmission electron microscopy (TEM), X-ray diffraction (XRD), FT-IR spectra and thermogravimetric analysis (TGA) were used to characterize the hybrid fibers. The hybrid fibers can be expected to have potential applications in drug release or tissue engineering because of their suitable pore size, large surface area and good biocompatibility.

  4. Electrochemical potentials of layered oxide and olivine phosphate with aluminum substitution: A first principles study

    Indian Academy of Sciences (India)

    Arun Kumar Varanasi; Phani Kanth Sanagavarapu; Arghya Bhowmik; Mridula Dixit Bharadwaj; Balasubramanian Narayana; Umesh V Waghmare; Dipti Deodhare; Alind Sharma

    2013-12-01

    First-principles prediction of enhancement in the electrochemical potential of LiCoO2 with aluminum substitution has been realized through earlier experiments. For safer and less expensive Li-ion batteries, it is desirable to have a similar enhancement for alternative cathode materials, LiFePO4 and LiCoPO4. Here, we present first-principles density functional theory based analysis of the effects of aluminum substitution on electrochemical potential of LiCoO2, LiFePO4 and LiCoPO4. While Al substitution for transition metal results in increase in electrochemical potential of LiCoO2, it leads to reduction in LiFePO4 and LiCoPO4. Through comparative topological analysis of charge density of these materials, we identify a ratio of Bader charges that correlates with electrochemical potential and determine the chemical origin of these contrasting effects: while electronic charge from lithium is transferred largely to oxygen in LiCoO2, it gets shared by the oxygen and Co/Fe in olivine phosphates due to strong covalency between O and Co/Fe. Our work shows that covalency of transition metal–oxygen bond plays a key role in determining battery potential.

  5. Oxidation of hydrogen-passivated silicon surfaces by scanning near-field optical lithography using uncoated and aluminum-coated fiber probes

    DEFF Research Database (Denmark)

    Madsen, Steen; Bozhevolnyi, Sergey I.; Birkelund, Karen;

    1997-01-01

    Optically induced oxidation of hydrogen-passivated silicon surfaces using a scanning near-field optical microscope was achieved with both uncoated and aluminum-coated fiber probes. Line scans on amorphous silicon using uncoated fiber probes display a three-peak profile after etching in potassium...... hydroxide. Numerical simulations of the electromagnetic field around the probe-sample interaction region are used to explain the experimental observations. With an aluminum-coated fiber probe, lines of 35 nm in width were transferred into the amorphous silicon layer. (C) 1997 American Institute of Physics....

  6. Thermal oxidation of single crystal aluminum antimonide and materials having the same

    Science.gov (United States)

    Sherohman, John William; Yee, Jick Hong; Coombs, III, Arthur William; Wu, Kuang Jen J.

    2012-12-25

    In one embodiment, a method for forming a non-conductive crystalline oxide layer on an AlSb crystal includes heat treating an AlSb crystal in a partial vacuum atmosphere at a temperature conducive for air adsorbed molecules to desorb, surface molecule groups to decompose, and elemental Sb to evaporate from a surface of the AlSb crystal and exposing the AlSb crystal to an atmosphere comprising oxygen to form a crystalline oxide layer on the surface of the AlSb crystal. In another embodiment, a method for forming a non-conductive crystalline oxide layer on an AlSb crystal includes heat treating an AlSb crystal in a non-oxidizing atmosphere at a temperature conducive for decomposition of an amorphous oxidized surface layer and evaporation of elemental Sb from the AlSb crystal surface and forming stable oxides of Al and Sb from residual surface oxygen to form a crystalline oxide layer on the surface of the AlSb crystal.

  7. Stability and corrosion resistance of superhydrophobic surface on oxidized aluminum in NaCl aqueous solution

    Science.gov (United States)

    Lv, Damei; Ou, Junfei; Xue, Mingshan; Wang, Fajun

    2015-04-01

    Superhydrophobic surface (SHS) was fabricated on aluminum via surface roughening by NaClO and surface passivation by hexadecyltrimethoxysilane. The long-term durability for storing the sample in air and the chemical stability for contacting the sample with NaCl solution were investigated. The short-term corrosion resistance for immersing the sample in NaCl solution for 1 h was investigated by potentiodynamic polarization, and the long-term corrosion resistance for immersing the sample in NaCl solution for 7 days was investigated by variation analyses on surface wettability, surface morphology, and surface chemistry. All experimental results suggested that the so-obtained SHS possessed good stability and good corrosion resistance under the testing conditions.

  8. 模板组装纳米结构氧化铈催化材料%The Study of Cerium Oxide Nanostructure Catalytic Materials by Templated Assemble

    Institute of Scientific and Technical Information of China (English)

    张久兴; 杜玉成; 孙立柏; 何洪

    2003-01-01

      介绍了模板剂结构诱导下均相沉淀法组装纳米结构氧化铈工艺方法.0.02mol SDS、0.01mol Ce(NO3)·6H2O、0.44mol (NH2)2CO,反应72h可获得肩峰较宽、具有CeO2,Ce2O3固溶峰的、粒径在5~10nm、孔径在3~5nm、比表面积达181.45m2/g的纳米结构氧化铈.N2吸附分析表明样品具有良好的吸附催化活性.%  In this paper, the nanostructure cerium-oxide-based surfactant mesophases templated by template agent assemblies were synthesized by homogeneous precipitation method. Nanostructure cerium oxide has been obtained, when SDS, cerium nitrate, urea were mixed at the molar ratio of 0.02mol, 0.01mol, 0.44mol and have been reacted 72h. The cerium oxide was characterized by a wider shoulder peak of CeO2 and Ce2O3, and the character with the mean particle size of 5~10nm, pore size 3~5nm, specific surface area of as large as 181.45m2/g. As catalyst, the sample has better absorption property by absorbed of nitrogen gas .

  9. A corrosion resistant cerium oxide based coating on aluminum alloy 2024 prepared by brush plating

    Energy Technology Data Exchange (ETDEWEB)

    Tang Junlei; Han Zhongzhi [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zuo Yu, E-mail: zuoy@mail.buct.edu.cn [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Tang Yuming [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2011-01-15

    Cerium oxide based coatings were prepared on AA2024 Al alloy by brush plating. The characteristic of this technology is that hydrogen peroxide, which usually causes the plating solution to be unstable, is not necessary in the plating electrolyte. The coating showed laminated structures and good adhesive strength with the substrate. X-ray diffraction and X-ray photoelectron spectroscopy analysis showed that the coatings were composed of Ce(III) and Ce(IV) oxides. The brush plated coatings on Al alloys improved corrosion resistance. The influence of plating parameters on structure and corrosion resistance of the cerium oxide based coating was studied.

  10. Graphene oxide nanosheets as an effective template for the synthesis of porous TiO2 film in dye-sensitized solar cells

    Science.gov (United States)

    Wang, Ping; He, Fenglong; Wang, Jin; Yu, Huogen; Zhao, Li

    2015-12-01

    Template method by using various organic components as the pore-forming agent is an effective strategy for the preparation of various porous inorganic materials. After high-temperature calcination in air, the organic components can be in situ decomposed into the gaseous CO2, resulting in the formation of porous structures in inorganic materials. In addition to the well-known organic components, it is highly required to develop new and simple carbon-containing template to prepare porous inorganic nanostructures. In this study, graphene oxide (GO) nanosheets were used as a new template for the preparation of porous TiO2 film photoelectrode, which can be applied in dye-sensitized solar cells (DSSCs). The porous TiO2 film was fabricated via a three-step method, including the initially homogeneous grafting of GO nanosheets on the TiO2 surface (TiO2-GO), the preparation of TiO2-GO film using blade method and final formation of porous structure after the in situ removal of GO by high-temperature calcination. The effect of GO content on photoelectric conversion performance of the as-fabricated DSSCs was investigated. It was found that the conversion efficiency of DSSC based on porous TiO2-GO (0.75%) film reached up to a maximum value (4.65%), which was much higher than that of DSSC based on nonporous TiO2 film (4.01%). The enhanced conversion efficiency can be attributed to the formation of more porous structures caused by the GO nanosheets after high-temperature calcination. This work may provide a new insight for preparing other porous structured materials.

  11. Synergistic Effect of Superhydrophobicity and Oxidized Layers on Corrosion Resistance of Aluminum Alloy Surface Textured by Nanosecond Laser Treatment.

    Science.gov (United States)

    Boinovich, Ludmila B; Emelyanenko, Alexandre M; Modestov, Alexander D; Domantovsky, Alexandr G; Emelyanenko, Kirill A

    2015-09-01

    We report a new efficient method for fabricating a superhydrophobic oxidized surface of aluminum alloys with enhanced resistance to pitting corrosion in sodium chloride solutions. The developed coatings are considered very prospective materials for the automotive industry, shipbuilding, aviation, construction, and medicine. The method is based on nanosecond laser treatment of the surface followed by chemisorption of a hydrophobic agent to achieve the superhydrophobic state of the alloy surface. We have shown that the surface texturing used to fabricate multimodal roughness of the surface may be simultaneously used for modifying the physicochemical properties of the thick surface layer of the substrate itself. Electrochemical and wetting experiments demonstrated that the superhydrophobic state of the metal surface inhibits corrosion processes in chloride solutions for a few days. However, during long-term contact of a superhydrophobic coating with a solution, the wetted area of the coating is subjected to corrosion processes due to the formation of defects. In contrast, the combination of an oxide layer with good barrier properties and the superhydrophobic state of the coating provides remarkable corrosion resistance. The mechanisms for enhancing corrosion protective properties are discussed. PMID:26271017

  12. Graphene Oxide/Polyacrylamide/Aluminum Ion Cross-Linked Carboxymethyl Hemicellulose Nanocomposite Hydrogels with Very Tough and Elastic Properties.

    Science.gov (United States)

    Kong, Weiqing; Huang, Danyang; Xu, Guibin; Ren, Junli; Liu, Chuanfu; Zhao, Lihong; Sun, Runcang

    2016-06-01

    Development of high-strength hydrogels has recently attracted ever-increasing attention. In this work, a new design strategy has been proposed to prepare graphene oxide (GO)/polyacrylamide (PAM)/aluminum ion (Al(3+) )-cross-linked carboxymethyl hemicellulose (Al-CMH) nanocomposite hydrogels with very tough and elastic properties. GO/PAM/Al-CMH hydrogels were synthesized by introducing graphene oxide (GO) into PAM/CMH hydrogel, followed by ionic cross-linking of Al(3+) . The nanocomposite hydrogels were characterized by means of FTIR, X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive X-ray analysis (SEM-EDX) along with their swelling and mechanical properties. The maximum compressive strength and the Young's modulus of GO3.5 /PAM/Al-CMH0.45 hydrogel achieved values of up to 1.12 and 13.27 MPa, increased by approximately 6488 and 18330 % relative to the PAM hydrogel (0.017 and 0.072 MPa). The as-prepared GO/PAM/Al-CMH nanocomposite hydrogels possess high strength and great elasticity giving them potential in bioengineering and drug-delivery system applications. PMID:27062081

  13. Nanowires and nanostructures fabrication using template methods

    DEFF Research Database (Denmark)

    Mátéfi-Tempfli, Stefan; Mátéfi-Tempfli, M.; Vlad, A.;

    2009-01-01

    One of the great challenges of today is to find reliable techniques for the fabrication of nanomaterials and nanostructures. Methods based on template synthesis and on self organization are the most promising due to their easiness and low cost. This paper focuses on the electrochemical synthesis...... of nanowires and nanostructures using nanoporous host materials such as supported anodic aluminum considering it as a key template for nanowires based devices. New ways are opened for applications by combining such template synthesis methods with nanolithographic techniques....

  14. Effect of aluminum addition on electrical properties, dielectric characteristics, and its stability of (Pr, Co, Cr, Y)-added zinc oxide-based varistors

    Indian Academy of Sciences (India)

    Choon-W Nahm

    2010-06-01

    The electrical properties, dielectric characteristics, and its stability against d.c. accelerated aging stress of (Pr, Co, Cr, Y)-added zinc oxide-based varistors were investigated for different aluminum concentrations under a sintering temperature of 1280°C. As the aluminum concentration increased, the average grain size () increased in the range of 4.3–5.5 m and the sintered density increased in the range of 5.63–5.67 g/cm3. As the aluminum concentration increased, the breakdown field decreased in the range of 6327–710 V/cm and the maximum nonlinear coefficient (46.9) was obtained for 0.005 mol% in aluminum concentration, further additions impaired the nonlinear properties. As the aluminum concentration increased, the apparent dielectric constant increased in the range of 500.5–1327.4 and dissipation factor increased in the range of 0.00493–0.0724. The varistor added with 0.001 mol% Al exhibited the highest stability for – characteristics in which % 1\\ mA is +1.4% and % is –5.7%, under stress state of 0.95 1\\ mA/150° C/24 h.

  15. Oxidation and decomposition mechanisms of air sensitive aluminum clusters at high heating rates

    Science.gov (United States)

    DeLisio, Jeffery B.; Mayo, Dennis H.; Guerieri, Philip M.; DeCarlo, Samantha; Ives, Ross; Bowen, Kit; Eichhorn, Bryan W.; Zachariah, Michael R.

    2016-09-01

    Molecular near zero oxidation state clusters of metals are of interest as fuel additives. In this work high heating rate decomposition of the Al(I) tetrameric cluster, [AlBr(NEt3)]4 (Et = C2H5), was studied at heating rates of up to 5 × 105 K/s using temperature-jump time-of-flight mass spectrometry (T-jump TOFMS). Gas phase Al and AlHx species were rapidly released during decomposition of the cluster, at ∼220 °C. The activation energy for decomposition was determined to be ∼43 kJ/mol. Addition of an oxidizer, KIO4, increased Al, AlO, and HBr signal intensities, showing direct oxidation of the cluster with gas phase oxygen.

  16. Preparation of Aligned Ultra-long and Diameter-controlled Silicon Oxide Nanotubes by Plasma Enhanced Chemical Vapor Deposition Using Electrospun PVP Nanofiber Template

    Science.gov (United States)

    Zhou, Ming; Zhou, Jinyuan; Li, Ruishan; Xie, Erqing

    2010-02-01

    Well-aligned and suspended polyvinyl pyrrolidone (PVP) nanofibers with 8 mm in length were obtained by electrospinning. Using the aligned suspended PVP nanofibers array as template, aligned ultra-long silicon oxide (SiO x) nanotubes with very high aspect ratios have been prepared by plasma-enhanced chemical vapor deposition (PECVD) process. The inner diameter (20-200 nm) and wall thickness (12-90 nm) of tubes were controlled, respectively, by baking the electrospun nanofibers and by coating time without sacrificing the orientation degree and the length of arrays. The micro-PL spectrum of SiO x nanotubes shows a strong blue-green emission with a peak at about 514 nm accompanied by two shoulders around 415 and 624 nm. The blue-green emission is caused by the defects in the nanotubes.

  17. Poly(furfuryl alcohol) nanospheres: a facile synthesis approach based on confinement effect of polymer and a template for synthesis of metal oxide hollow nanospheres

    Indian Academy of Sciences (India)

    Wei-Zhi Wang; Zhi-Qiang Li; Kong-Lin Wu; Ya-Jing Lu; Ya-Fei Xu; Xin-Jie Song

    2015-12-01

    This paper describes a facile hydrothermal approach to the large-scale synthesis of well-dispersed poly(furfuryl alcohol) (PFA) nanospheres with an average diameter of 350 nm in the presence of poly(vinyl pyrrolidone) (PVP). Scanning electron microscopy and transmission electron microscopy studies showed that different morphologies of PFA could be obtained by adjusting the ratio of PVP and furfuryl alcohol (FA). As a whole, the results demonstrate that PVP plays a key role in controlling the polymerization process of FA. The confinement effect of PVP is proposed to explain the formation process of PFA nanospheres. Furthermore, the as-prepared PFA nanospheres have a functional surface that allow them to act as an ideal template for fabricating metal oxide hollow nanospheres.

  18. Selection of crucible oxides in molten titanium and titanium aluminum alloys by thermo-chemistry calculations

    OpenAIRE

    Kostov A.; Friedrich B

    2005-01-01

    Titanium and its alloys interstitially dissolve a large amount of impurities such as oxygen and nitrogen, which degrade the mechanical and physical properties of alloys. On the other hand crucible oxides based on CaO, ZrO2 Y2O3, etc., and their spinels (combination of two or more oxides) can be used for melting titanium and its alloys. However, the thermodynamic behavior of calcium, zirconium, yttrium on the one side, and oxygen on the other side, in molten Ti and Ti-Al alloys have not been m...

  19. Studies on anodic oxide coating with low absorptance and high emittance on aluminum alloy 2024

    Energy Technology Data Exchange (ETDEWEB)

    Siva Kumar, C. [Department of Post-graduate studies in Chemistry, Central College, Bangalore (India); Sharma, A.K. [Thermal Process Section, ISRO Satellite Centre, Vimanapura Post, Bangalore (India); Mahendra, K.N.; Mayanna, S.M. [Department of Post-graduate studies in Chemistry, Central College, Bangalore (India)

    2000-01-01

    Anodization of AA 2024 in sulfuric acid bath containing glycerol, lactic acid and ammonium metavenadate has been studied to develop white anodic oxide coating. Investigation on the influence of various operating parameters - coating thickness, current density and ammonium metavenadate concentration on the optical properties was carried out to optimize the process. Infrared, atomic absorption spectroscopic techniques and scanning electron micrograph were used to characterize the coating. The obtained oxide coating provides a ratio of solar absorptance ({alpha}) to infrared emittance ({epsilon}), as low as 0.2. The optical properties and hardness values measured under optimum experimental conditions support its use as a thermal control coating.

  20. Pretreatment with H2O2 Alleviates Aluminum-induced Oxidative Stress in Wheat Seedlings

    Institute of Scientific and Technical Information of China (English)

    Fang Jie Xu; Chong Wei Jin; Wen Jing Liu; Yong Song Zhang; Xian Yong Lin

    2011-01-01

    Hydrogen peroxide(H2O2)is a key reactive oxygen species(ROS)in signal transduction pathways Ieading to activation of plant defenses against biotic and abiotic stresses.In this study,we investigated the effects of H2O2 pretreatment on aluminum (Al)induced antioxidant responses in root tips of two wheat(Triticum aestivum L.)genotypes,Yangmai-5(Al-sensitive)and Jian-864(Al-tolerant).Al increased and root elongation inhibition in Yangmai-5 than in Jian-864.However,H2O2 pretreatment alleviated Alinduced deleterious effects in both genotypes.Under Al stress,H2O2 pretreatment increased the activities of superoxide dismutase,catalase,peroxidase,ascorbate peroxidase and monodehydroascorbate reductase,glutathione reductase and giutathione peroxidase as well as the levels of ascorbate and glutathione more significantly in Yangmai-5 than in Jian-864.Furthermore,H2O2 pretreatment also increased the total antioxidant capacity evaluated as the 2,2-diphenyl-1-picrylhydrazyl-radical scavenging activity and the ferric reducing/antioxidant power more significantly in Yangmai-5 than in Jian-864.Therefore,we conclude that H2O2 pretreatment improves wheat Al acclimation during subsequent Al exposure by enhancing the antioxidant defense capacity,which prevents ROS accumulation,and that the enhancement is greater in the Al-sensitive genotype than in the Al-tolerant genotype.

  1. The Effect of Microarc Oxidation (MAO Modes on Corrosion Behavior of High-Silicon Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    S.К. Kiselyeva

    2014-07-01

    Full Text Available The investigation studies the properties of hardened surface layers, developed with the microarc oxidation method (MAO on ingots of a Al-Si alloy. It has been proved that properties of the developed surfaces (microhardness, thickness, porosity and corrosion properties depend on the concentration of electrolyte components.

  2. Vertical arrays of SiO2 micro/nanotubes templated from Si pillars by chemical oxidation for high loading capacity buoyant aquatic devices.

    Science.gov (United States)

    Yoon, Sung-Soo; Khang, Dahl-Young

    2013-12-26

    A simple and facile method to fabricate SiO2 micro- or nanotubes has been demonstrated based on room temperature wet chemical oxidation of a porous layer of Si pillar templates that have been prepared by metal-assisted chemical etching (MaCE). Under typical conditions, Si pillars produced by the MaCE have been found to be covered with a thin nanoporous Si layer. The porous Si skin layer has been chemically oxidized by simple dipping in AgNO3 solution at room temperature, which has led to seamless SiO2 shell layer thanks to the accompanying volume expansion during the wet oxidation. Following wet removal of core Si by KOH yields the SiO2 micro- or nanotubes, either in test tube shape or in open shape at both ends, depending on processing method. The vertical arrays of the SiO2 tube on the Si substrate, after hydrophobic siloxane oligomer printing, has been found to have very large loading capacity on water, due to extremely high porosity (>90%) and good enough mechanical stability. The novel method to fabricate SiO2 tubes can shed new light in design of novel aquatic devices, other than simple mimicking the leg of a water strider. Also, the method may be very helpful in various applications of SiO2 nanotubes. PMID:24313459

  3. Assembly of crosslinked oxo-cyanoruthenate and zirconium oxide bilayers: Application in electrocatalytic films based on organically modified silica with templated pores

    Science.gov (United States)

    Rutkowska, Iwona A.; Sek, Jakub P.; Mehdi, B. Layla; Kulesza, Pawel J.; Cox, James A.

    2014-01-01

    Electrochemical deposition of crosslinked oxo-cyanoruthenate, Ru-O/CN-O, from a mixture of RuCl3 and K4Ru(CN)6 is known to yield a film on glassy carbon that promotes oxidations by a combination of electron and oxygen transfer. Layer-by-layer (LbL) deposition of this species and of a film formed by cycling of the electrode potential in a ZrO2 solution systematically increases the number of catalytically active sites of the Ru-O/CN-O on the electrode. The evaluation of the electrocatalytic activity was by cyclic voltammetric oxidation of cysteine at pH 2. Plots of the anodic peak current vs. the square root of scan rate were indicative of linear diffusion control of this oxidation, even in the absence of ZrO2, but the slopes of these linear plots increased with bilayer number, n, of (ZrO2 | Ru-O/CN-O)n. The latter observation is hypothesized to be due to an increased number of active sites for a given geometric electrode area, but proof required further study. To optimize utilization of the catalyst and to provide a size-exclusion characteristic to the electrode, the study was extended to LbL deposition of the composite in 50-nm pores of an organically modified silica film deposited by electrochemically assisted sol-gel processing using surface-bound poly(styrene sulfonate) nanospheres as a templating agent. PMID:24683266

  4. Assembly of crosslinked oxo-cyanoruthenate and zirconium oxide bilayers: Application in electrocatalytic films based on organically modified silica with templated pores.

    Science.gov (United States)

    Rutkowska, Iwona A; Sek, Jakub P; Mehdi, B Layla; Kulesza, Pawel J; Cox, James A

    2014-03-10

    Electrochemical deposition of crosslinked oxo-cyanoruthenate, Ru-O/CN-O, from a mixture of RuCl3 and K4Ru(CN)6 is known to yield a film on glassy carbon that promotes oxidations by a combination of electron and oxygen transfer. Layer-by-layer (LbL) deposition of this species and of a film formed by cycling of the electrode potential in a ZrO2 solution systematically increases the number of catalytically active sites of the Ru-O/CN-O on the electrode. The evaluation of the electrocatalytic activity was by cyclic voltammetric oxidation of cysteine at pH 2. Plots of the anodic peak current vs. the square root of scan rate were indicative of linear diffusion control of this oxidation, even in the absence of ZrO2, but the slopes of these linear plots increased with bilayer number, n, of (ZrO2 | Ru-O/CN-O) n . The latter observation is hypothesized to be due to an increased number of active sites for a given geometric electrode area, but proof required further study. To optimize utilization of the catalyst and to provide a size-exclusion characteristic to the electrode, the study was extended to LbL deposition of the composite in 50-nm pores of an organically modified silica film deposited by electrochemically assisted sol-gel processing using surface-bound poly(styrene sulfonate) nanospheres as a templating agent.

  5. Carbonaceous spheres—an unusual template for solid metal oxide mesoscale spheres: Application to ZnO spheres

    Energy Technology Data Exchange (ETDEWEB)

    Patrinoiu, Greta; Calderón-Moreno, Jose Maria; Culita, Daniela C. [Illie Murgulescu Institute of Physical Chemistry, Romanian Academy, Splaiul Independentei 202, 060021 Bucharest (Romania); Birjega, Ruxandra [National Institute for Lasers, Plasma and Radiation Physics, P.O. Box Mg—27, Magurele, Bucharest (Romania); Ene, Ramona [Ilie Murgulescu Institute of Physical Chemistry, Romanian Academy, Splaiul Independentei 202, 060021 Bucharest (Romania); Carp, Oana, E-mail: ocarp@icf.ro [Ilie Murgulescu Institute of Physical Chemistry, Romanian Academy, Splaiul Independentei 202, 060021 Bucharest (Romania)

    2013-06-15

    A green template route for the synthesis of mesoscale solid ZnO spheres was ascertained. The protocol involves a double coating of the carbonaceous spheres with successive layers of zinc-containing species by alternating a non-ultrasound and ultrasound-assisted deposition, followed by calcination treatments. The composites were characterized by FTIR spectroscopy, thermal analysis, scanning electron microscopy while the obtained ZnO spheres by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopy, N{sub 2} adsorption–desorption isotherms and photoluminescence investigations. A growth mechanism of the solid spheres is advanced based on these results. While the spheres' diameters and the mean size values of ZnO are independent on deposition order, the surface area and the external porosity are fairly dependent. The photoluminescence measurements showed interesting emission features, with emission bands in the violet to orange region. The spheres present high photocatalytical activity towards the degradation of phenol under UV irradiation, the main reaction being its mineralization. - Graphical abstract: A novel and eco-friendly methodology for the synthesis of mesoscale solid ZnO spheres was developed. The protocol involves a double coating of the starch-derived carbonaceous spheres with successive layers of zinc-containing species by alternating a non-ultrasound and ultrasound-assisted deposition, followed by calcination treatments. - Highlights: • ZnO solid spheres are obtained via a template route using carbonaceous spheres. • Two-step coatings of interchangeable order are used as deposition procedure. • The coating procedure influences the porosity and surface area. • ZnO spheres exhibited interesting visible photoluminescence properties. • Solid spheres showed photocatalytical activity in degradation of phenol.

  6. Fractionation of fulvic acid by iron and aluminum oxides: influence on copper toxicity to Ceriodaphnia dubia

    Science.gov (United States)

    Smith, Kathleen S.; James F. Ranville; Emily K. Lesher; Daniel J. Diedrich; Diane M. McKnight; Ruth M. Sofield

    2014-01-01

    This study examines the effect on aquatic copper toxicity of the chemical fractionation of fulvic acid (FA) that results from its association with iron and aluminum oxyhydroxide precipitates. Fractionated and unfractionated FAs obtained from streamwater and suspended sediment were utilized in acute Cu toxicity tests on ,i>Ceriodaphnia dubia. Toxicity test results with equal FA concentrations (6 mg FA/L) show that the fractionated dissolved FA was 3 times less effective at reducing Cu toxicity (EC50 13 ± 0.6 μg Cu/L) than were the unfractionated dissolved FAs (EC50 39 ± 0.4 and 41 ± 1.2 μg Cu/L). The fractionation is a consequence of preferential sorption of molecules having strong metal-binding (more aromatic) moieties to precipitating Fe- and Al-rich oxyhydroxides, causing the remaining dissolved FA to be depleted in these functional groups. As a result, there is more bioavailable dissolved Cu in the water and hence greater potential for Cu toxicity to aquatic organisms. In predicting Cu toxicity, biotic ligand models (BLMs) take into account dissolved organic carbon (DOC) concentration; however, unless DOC characteristics are accounted for, model predictions can underestimate acute Cu toxicity for water containing fractionated dissolved FA. This may have implications for water-quality criteria in systems containing Fe- and Al-rich sediment, and in mined and mineralized areas in particular. Optical measurements, such as specific ultraviolet absorbance at 254 nm (SUVA254), show promise for use as spectral indicators of DOC chemical fractionation and inferred increased Cu toxicity.

  7. The effect of Bi{sup 3+} and Li{sup +} co-doping on the luminescence characteristics of Eu{sup 3+}-doped aluminum oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Padilla-Rosales, I., E-mail: ipadilla@cinvestav.mx [Centro de Investigación y de Estudios Avanzados del IPN, Nanociencias y Nanotecnología, Av. IPN 2508, Col. San Pedro Zacatenco, CP 07360 México D.F. (Mexico); Martinez-Martinez, R. [Instituto de Física y Matemáticas, Universidad Tecnológica de la Mixteca, Carretera a Acatlima Km. 2.5, CP 69000 Huajuapan de León, Oax, México (Mexico); Cabañas, G. [Centro de Investigación y de Estudios Avanzados del IPN, Nanociencias y Nanotecnología, Av. IPN 2508, Col. San Pedro Zacatenco, CP 07360 México D.F. (Mexico); Falcony, C. [Centro de Investigación y de Estudios Avanzados del IPN, Departamento de Física, Av. IPN 2508, Col. San Pedro Zacatenco, CP 07360 México D.F. (Mexico)

    2015-09-15

    The incorporation of Bi{sup 3+} and Li{sup +} as co-dopants in Eu{sup 3+}-doped aluminum oxide films deposited by the ultrasonic spray pyrolysis technique and its effect on the luminescence characteristics of this material are described. Both Bi{sup 3+} and Li{sup +} do not introduce new luminescence features but affect the luminescence intensity of the Eu{sup 3+} related emission spectra as well as the excitation spectra. The introduction of Bi{sup 3+} generates localized states in the aluminum oxide host that result in a quenching of the luminescence intensity, while Li{sup +} and Bi{sup 3+} co-doping increase the luminescence intensity of these films. - Highlights: • Li and Bi co-doping increase the luminescence. • Bi creates localized states in the Al{sub 2}O{sub 3} host. • Li was incorporated as a co-activator.

  8. Aluminum-, Calcium- And Titanium-Rich Oxide Stardust In Ordinary Chondrite Meteorites

    CERN Document Server

    Nittler, Larry R; Gallino, Roberto; Hoppe, Peter; Nguyen, Ann N; Stadermann, Frank J; Zinner, Ernst K

    2008-01-01

    We report isotopic data for a total of 96 presolar oxide grains found in residues of several unequilibrated ordinary chondrite meteorites. Identified grain types include Al2O3, MgAl2O4, hibonite (CaAl12O19) and Ti oxide. This work greatly increases the presolar hibonite database, and is the first report of presolar Ti oxide. O-isotopic compositions of the grains span previously observed ranges and indicate an origin in red giant and asymptotic giant branch (AGB) stars of low mass (<2.5 MSun) for most grains. Cool bottom processing in the parent AGB stars is required to explain isotopic compositions of many grains. Potassium-41 enrichments in hibonite grains are attributable to in situ decay of now-extinct 41Ca. Inferred initial 41Ca/40Ca ratios are in good agreement with model predictions for low-mass AGB star envelopes, provided that ionization suppresses 41Ca decay. Stable Mg and Ca isotopic ratios of most of the hibonite grains reflect primarily the initial compositions of the parent stars and are gener...

  9. DEGRADATION OF SM2ZR2O7 THERMAL BARRIER COATING CAUSED BY CALCIUM-MAGNESIUM-ALUMINUM-SILICON OXIDE (CMAS) DEPOSITION

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Honglong; Sheng, Zhizhi; Tarwater, Emily; Zhang, Xingxing; Dasgupta, Sudip; Fergus, Jeffrey

    2015-03-16

    Rare earth zirconates are promising materials for use as thermal barrier coatings in gas turbine engines. Among the lanthanide zirconate materials, Sm2Zr2O7 with the pyrochlore structure has lower thermal conductivity and better corrosion resistance against calcium-magnesium-aluminum-silicon oxide (CMAS). In this work, after reaction with CMAS, the pyrochlore structure transforms to the cubic fluorite structure and Ca2Sm8(SiO4)6O2 forms in elongated grain.

  10. On the kinetics of the aluminum-water reaction during exposure in high-heat flux test loops: 1, A computer program for oxidation calculations

    International Nuclear Information System (INIS)

    The ''Griess Correlation,'' in which the thickness of the corrosion product on aluminum alloy surfaces is expressed as a function of time and temperature for high-flux-reactor conditions, was rewritten in the form of a simple, general rate equation. Based on this equation, a computer program that calculates oxide-layer thickness for any given time-temperature transient was written. 4 refs

  11. Fabrication of aluminum foam from aluminum scrap Hamza

    Directory of Open Access Journals (Sweden)

    O. A. Osman1 ,

    2015-02-01

    Full Text Available In this study the optimum parameters affecting the preparation of aluminum foam from recycled aluminum were studied, these parameters are: temperature, CaCO3 to aluminum scrap wt. ratio as foaming agent, Al2O3 to aluminum scrap wt. ratio as thickening agent, and stirring time. The results show that, the optimum parameters are the temperature ranged from 800 to 850oC, CaCO3 to aluminum scrap wt. ratio was 5%, Al2O3 to aluminum scrap wt. ratio was 3% and stirring time was 45 second with stirring speed 1200 rpm. The produced foam apparent densities ranged from 0.40-0.60 g/cm3. The microstructure of aluminum foam was examined by using SEM, EDX and XRD, the results show that, the aluminum pores were uniformly distributed along the all matrices and the cell walls covered by thin oxide film.

  12. Integrative functional transcriptomic analyses implicate specific molecular pathways in pulmonary toxicity from exposure to aluminum oxide nanoparticles.

    Science.gov (United States)

    Li, Xiaobo; Zhang, Chengcheng; Bian, Qian; Gao, Na; Zhang, Xin; Meng, Qingtao; Wu, Shenshen; Wang, Shizhi; Xia, Yankai; Chen, Rui

    2016-09-01

    Gene expression profiling has developed rapidly in recent years and it can predict and define mechanisms underlying chemical toxicity. Here, RNA microarray and computational technology were used to show that aluminum oxide nanoparticles (Al2O3 NPs) were capable of triggering up-regulation of genes related to the cell cycle and cell death in a human A549 lung adenocarcinoma cell line. Gene expression levels were validated in Al2O3 NPs exposed A549 cells and mice lung tissues, most of which showed consistent trends in regulation. Gene-transcription factor network analysis coupled with cell- and animal-based assays demonstrated that the genes encoding PTPN6, RTN4, BAX and IER play a role in the biological responses induced by the nanoparticle exposure, which caused cell death and cell cycle arrest in the G2/S phase. Further, down-regulated PTPN6 expression demonstrated a core role in the network, thus expression level of PTPN6 was rescued by plasmid transfection, which showed ameliorative effects of A549 cells against cell death and cell cycle arrest. These results demonstrate the feasibility of using gene expression profiling to predict cellular responses induced by nanomaterials, which could be used to develop a comprehensive knowledge of nanotoxicity. PMID:26830206

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

    Science.gov (United States)

    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.

  14. Facile fabrication of Ag dendrite-integrated anodic aluminum oxide membrane as effective three-dimensional SERS substrate

    Science.gov (United States)

    Zhang, Cong-yun; Lu, Ya; Zhao, Bin; Hao, Yao-wu; Liu, Ya-qing

    2016-07-01

    A novel surface enhanced Raman scattering (SERS)-active substrate has been successfully developed, where Ag-dendrites are assembled on the surface and embedded in the channels of anodic aluminum oxide (AAO) membrane, via electrodeposition in AgNO3/PVP aqueous system. Reaction conditions were systematically investigated to attain the best Raman enhancement. The growth mechanism of Ag dendritic nanostructures has been proposed. The Ag dendrite-integrated AAO membrane with unique hierarchical structures exhibits high SERS activity for detecting rhodamine 6G with a detection limit as low as 1 × 10-11 M. Furthermore, the three-dimensional (3D) substrates display a good reproducibility with the average intensity variations at the major Raman peak less than 12%. Most importantly, the 3D SERS substrates without any surface modification show an outstanding SERS response for the molecules with weak affinity for noble metal surfaces. The potential application for the detection of polycyclic aromatic hydrocarbons (PAHs) was evaluated with fluoranthene as Raman target molecule and a sensitive SERS detection with a limit down to 10-8 M was reached. The 3D SERS-active substrate shows promising potential for rapid detection of trace organic pollutants even weak affinity molecules in the environment.

  15. Preparation and characterization of solid-state sintered aluminum-doped zinc oxide with different alumina contents

    Indian Academy of Sciences (India)

    Yu-Hsien Chou; J L H Chau; W L Wang; C S Chen; S H Wang; C C Yang

    2011-06-01

    Aluminum-doped zinc oxide (AZO) ceramics with 0−2.5 wt.% alumina (Al2O3) content were prepared using a solid-state reaction technique. It was found that AZO grains became finer in size and more irregular in shape than undoped ZnO as the Al2O3 content increased. Addition of Al2O3 dopant caused the formation of phase transformation stacking faults in ZnO grains. The second phase, ZnAl2O4 spinel, was observed at the grain boundaries and triple junctions, and inside the grains. In this study, a 3-inch circular Al2O3 (2 wt.%)-doped ZnO ceramic target sintered at 1500°C for 6 h has a relative density of 99.8% with a resistivity of 1.8 × 10-3 -cm. The AZO film exhibits optical transparency of 90.3% in the visible region and shows an electrical resistivity of 2.5 × 10-3 -cm.

  16. Nanoporous anodic aluminum oxide as a promising material for the electrostatically-controlled thin film interference filter

    International Nuclear Information System (INIS)

    This study presents the approach to implement the electrostatically-controlled thin film optical filter by using a nanoporous anodic aluminum oxide (np-AAO) layer as the key suspended micro structure. The bi-stable optical filter operates in the visible spectral range. In this work, the presented bi-stable optical filter has averaged reflectivity of 60%, and the central wavelengths are 580 and 690 nm respectively for on and off states. The presented np-AAO layer offers the following merits for the thin film optical filter: (1) material properties of np-AAO film, such as refractive index, elastic modulus and dielectric constant, can be easily changed by a low temperature pore-widening process, (2) in-use stiction of the suspended np-AAO structure can be reduced by the small contact area of nanoporous textures, (3) driving (pull-in) voltage can be reduced due to a large dielectric constant (εAAO is 7.05) and small stiffness of np-AAO film and (4) dielectric charging can be reduced by the np-AAO material; thus the offset voltage is small. The study reports the design, fabrication and experimental results of the bi-stable optical filter to demonstrate the advantages of the presented device. The np-AAO material also has the potential for applications of other electrostatic drive micro devices. (paper)

  17. Wide band gap semiconductor templates

    Energy Technology Data Exchange (ETDEWEB)

    Arendt, Paul N. (Los Alamos, NM); Stan, Liliana (Los Alamos, NM); Jia, Quanxi (Los Alamos, NM); DePaula, Raymond F. (Santa Fe, NM); Usov, Igor O. (Los Alamos, NM)

    2010-12-14

    The present invention relates to a thin film structure based on an epitaxial (111)-oriented rare earth-Group IVB oxide on the cubic (001) MgO terminated surface and the ion-beam-assisted deposition ("IBAD") techniques that are amendable to be over coated by semiconductors with hexagonal crystal structures. The IBAD magnesium oxide ("MgO") technology, in conjunction with certain template materials, is used to fabricate the desired thin film array. Similarly, IBAD MgO with appropriate template layers can be used for semiconductors with cubic type crystal structures.

  18. Deposition of duplex Al 2O 3/aluminum coatings on steel using a combined technique of arc spraying and plasma electrolytic oxidation

    Science.gov (United States)

    Gu, Weichao; Shen, Dejiu; Wang, Yulin; Chen, Guangliang; Feng, Wenran; Zhang, Guling; Fan, Songhua; Liu, Chizi; Yang, Size

    2006-02-01

    Plasma electrolytic oxidation (PEO) is a cost-effective technique that can be used to prepare ceramic coatings on metals such as Ti, Al, Mg, Nb, etc., and their alloys, but this promising technique cannot be used to modify the surface properties of steels, which are the most widely used materials in engineering. In order to prepare metallurgically bonded ceramic coatings on steels, a combined technique of arc spraying and plasma electrolytic oxidation (PEO) was adopted. In this work, metallurgically bonded ceramic coatings on steels were obtained using this method. We firstly prepared aluminum coatings on steels by arc spraying, and then obtained the metallurgically bonded ceramic coatings on aluminum coatings by PEO. The characteristics of duplex coatings were analyzed by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The corrosion and wear resistance of the ceramic coatings were also studied. The results show that, duplex Al 2O 3/aluminum coatings have been deposited on steel substrate after the combined treatment. The ceramic coatings are mainly composed of α-Al 2O 3, γ-Al 2O 3, θ-Al 2O 3 and some amorphous phase. The duplex coatings show favorable corrosion and wear resistance properties. The investigations indicate that the combination of arc spraying and plasma electrolytic oxidation proves a promising technique for surface modification of steels for protective purposes.

  19. Oxidation study on as-bonded intermetallic of copper wire-aluminum bond pad metallization for electronic microchip

    Energy Technology Data Exchange (ETDEWEB)

    Joseph Sahaya Anand, T., E-mail: anand@utem.edu.my [Faculty of Manufacturing Engineering, University Technical Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka (Malaysia); Yau, Chua Kok [Faculty of Manufacturing Engineering, University Technical Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka (Malaysia); University of Technical Malaysia Supported by Infineon Technology - Malaysia - Sdn. Bhd., Melaka (Malaysia); Huat, Lim Boon [Department of Innovation, Infineon Technology - Malaysia - Sdn. Bhd., FTZ Batu Berendam, 75350 Melaka (Malaysia)

    2012-10-15

    In this work, influence of Copper free air ball (FAB) oxidation towards Intermetallic Compound (IMC) at Copper wire-Aluminum bond pad metallization (Cu/Al) is studied. Samples are synthesized with different Copper FAB oxidation condition by turning Forming Gas supply ON and OFF. Studies are performed using Optical Microscope (OM), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and line-scan Energy Dispersive X-ray (EDX). SEM result shows there is a cross-sectional position offset from center in sample synthesized with Forming Gas OFF. This is due to difficulty of determining the position of cross-section in manual grinding/polishing process and high occurrence rate of golf-clubbed shape of oxidized Copper ball bond. TEM inspection reveals that the Copper ball bond on sample synthesized with Forming Gas OFF is having intermediate oxidation. Besides, the presence of IMC at the bonding interface of Cu/Al for both samples is seen. TEM study shows voids form at the bonding interface of Forming Gas ON sample belongs to unbonded area; while that in Forming Gas OFF sample is due to volume shrinkage of IMC growth. Line-scan EDX shows the phases present in the interfaces of as-bonded samples are Al{sub 4}Cu{sub 9} ({approx}3 nm) for sample with Forming Gas ON and mixed CuAl and CuAl{sub 2} ({approx}15 nm) for sample with Forming Gas OFF. Thicker IMC in sample with Forming Gas OFF is due to cross-section is positioned at high stress area that is close to edge of ball bond. Mechanical ball shear test shows that shear strength of sample with Forming Gas OFF is about 19% lower than that of sample with Forming Gas ON. Interface temperature is estimated at 437 Degree-Sign C for as-bonded sample with Forming Gas ON by using empirical parabolic law of volume diffusion. -- Highlights: Black-Right-Pointing-Pointer 3 nm Al{sub 4}Cu{sub 9} are found in sample prepared with Forming Gas ON. Black-Right-Pointing-Pointer 15 nm mixed CuAl + CuAl{sub 2} are found

  20. Yttrium aluminum garnet (YAG) obtained by rare-earth mixed oxide (RE{sub 2}O{sub 3})

    Energy Technology Data Exchange (ETDEWEB)

    Castro, D.F.; Daguano, J.K.M.F.; Rodrigues Junior, D., E-mail: claudinei@demar.eel.usp.b [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia; Santos, C. [Centro Universitario de Volta Redonda (MEMAT/UNIFOA), RJ (Brazil); Suzuki, P.A. [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas, SP (Brazil); Silva, O.M.M. [Centro Tecnico Aeroespacial (CTA-IAE), Sao Jose dos Campos, SP (Brazil). Inst. de Atividades Espaciais. Div. de Materiais

    2010-07-01

    In this work, the substitution of commercial Y{sub 2}O{sub 3} by a rare earth mixed oxide, RE{sub 2}O{sub 3}, to form Yttrium aluminum Garnet-Y{sub 3}Al{sub 5}O{sub 12}, was investigated. Al{sub 2}O{sub 3}:Y{sub 2}O{sub 3} and Al{sub 2}O{sub 3}:RE{sub 2}O{sub 3} powder-mixtures, in a molar ratio of 60:40, were milled and subsequently cold uniaxially-pressed. Compacts were sintered at 1000, 1400 or 1600 deg C, for 120 minutes. RE{sub 2}O{sub 3} oxide was characterized by high-resolution synchrotron X-ray diffraction (HRXRD) and compared to Y{sub 2}O{sub 3}. X-ray diffraction pattern of the RE{sub 2}O{sub 3} indicates a true solid solution formation. Rietveld refinement of the sintered YAG and (RE)AG reveled a similar crystal structure to the YAGs obtained by the use of Al{sub 2}O{sub 3}-Y{sub 2}O{sub 3} or Al{sub 2}O{sub 3}-RE{sub 2}O{sub 3} respectively. Microstructural analysis of both, YAG or (RE)AG, revealed similar grain sizes of about 2.5 {mu}m besides mechanical properties, with hardness of 400HV and fracture toughness of 3.8MPa.m1/2. It could be, thus, demonstrated that pure Y{sub 2}O{sub 3} can be substituted by the rare-earth solid solution, RE{sub 2}O{sub 3}, in the formation YAGs, presenting similar microstructural and mechanical properties. (author)

  1. Influence of sodium silicate concentration on structural and tribological properties of microarc oxidation coatings on 2017A aluminum alloy substrate

    Energy Technology Data Exchange (ETDEWEB)

    Polat, Aytekin, E-mail: apolat@nigde.edu.t [Department of Mechanical Engineering, Nigde University, Nigde 51100 (Turkey); Makaraci, Murat [Department of Mechanical Engineering, Kocaeli University, Kocaeli (Turkey); Usta, Metin [Department of Materials Science and Engineering, Gebze Institute of Technology, Kocaeli (Turkey)

    2010-08-20

    In this paper, thick and hard oxide coatings resistant to wear were produced on 2017A-T6 Al alloy by the microarc oxidation (MAO) technique in an alkali electrolyte consisting of different sodium silicate concentrations (0-8 g/l). The coatings were characterized by means of optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and surface profilometry. Microhardness, scratch adhesion and pin-on-disk sliding wear tests were also performed to evaluate the tribological properties of the coatings. The influence of sodium silicate concentration on the structural and tribological properties of the MAO coatings was discussed. Results reveal that increasing sodium silicate concentration from 0 to 8 g/l in the electrolyte caused an increase in the electrolyte conductivity (from 7.71 to 18.1 mS/cm) and a decrease in positive final voltage (from 627 to 590 V) in the MAO process. In response to the increase in sodium silicate concentration, the thickness, surface roughness (R{sub a}) and critical load (L{sub c}) corresponding to adhesive failure of the coatings were increased simultaneously from 74 to 144 {mu}m, and 4.4 to 6.58 {mu}m, and 127.76 to 198.54 N, respectively. At the same time, the phase structure and composition of the coatings also varied by the participation of silicate ions in the reactions and their incorporation into the coating structure. Moreover, it was observed that the coating formed in the low sodium silicate concentration (4 g/l) had higher surface hardness (2020 HV) and improved wear resistance than the one (1800 HV) formed in the high sodium silicate concentration (8 g/l). The coatings produced in three different electrolytic solutions provided an excellent wear resistance and a load carrying capacity compared to the uncoated aluminum alloy.

  2. Oxidation and corrosion behavior of titanium aluminum nitride coatings by arc ion plating

    Institute of Scientific and Technical Information of China (English)

    LI Ming-sheng; FENG Chang-jie; ZHANG Zhi-feng; WANG Fu-hui

    2006-01-01

    Composite metastable TiN and Ti1-xAlxN coatings with different Al content were deposited on 1Cr11Ni2W2MoV stainless steel for aero-engine compressor blades by arc ion plating. The results show that all coatings have a B1NaCl structure and the preferred orientation changes from (111) to (220) with increasing Al content; the lattice parameter of Ti1-xAlxN decreases with the increase of Al content. The oxidation-resistance of (Ti,Al)N coatings is significantly improved owing to the formation of Al-riched oxide on the surface of the coatings. The nitride coatings can significantly improve the corrosion-resistance of 1Cr11Ni2W2MoV stainless steel under the synergistic of water vapor and NaCl, and the corrosion-resistance becomes better when the Al content increases, because not only the quick formation of thin alumina layer prevents the further corrosion but also the formation of alumina seals the pinholes or defects in the coatings, which prevents the occurrence of localized nodules-like corrosion.

  3. High temperature oxidation behavior of gamma-nickel+gamma'-nickel aluminum alloys and coatings modified with platinum and reactive elements

    Science.gov (United States)

    Mu, Nan

    Materials for high-pressure turbine blades must be able to operate in the high-temperature gases (above 1000°C) emerging from the combustion chamber. Accordingly, the development of nickel-based superalloys has been constantly motivated by the need to have improved engine efficiency, reliability and service lifetime under the harsh conditions imposed by the turbine environment. However, the melting point of nickel (1455°C) provides a natural ceiling for the temperature capability of nickel-based superalloys. Thus, surface-engineered turbine components with modified diffusion coatings and overlay coatings are used. Theses coatings are capable of forming a compact and adherent oxide scale, which greatly impedes the further transport of reactants between the high-temperature gases and the underlying metal and thus reducing attack by the atmosphere. Typically, these coatings contain beta-NiAl as a principal constituent phase in order to have sufficient aluminum content to form an Al2O3 scale at elevated temperatures. The drawbacks to the currently-used beta-based coatings, such as phase instabilities, associated stresses induced by such phase instabilities, and extensive coating/substrate interdiffusion, are major motivations in this study to seek next-generation coatings. The high-temperature oxidation resistance of novel Pt+Hf-modified gamma-Ni+gamma'-Ni 3Al-based alloys and coatings were investigated in this study. Both early-stage and 4-days isothermal oxidation behavior of single-phase gamma-Ni and gamma'-Ni3Al alloys were assessed by examining the weight changes, oxide-scale structures, and elemental concentration profiles through the scales and subsurface alloy regions. It was found that Pt promotes Al 2O3 formation by suppressing the NiO growth on both gamma-Ni and gamma'-Ni3Al single-phase alloys. This effect increases with increasing Pt content. Moreover, Pt exhibits this effect even at lower temperatures (˜970°C) in the very early stage of oxidation. It

  4. Kinetic of sintering of polyethilene glycol and lanthanum dopped aluminum oxide obtained by the sol-gel method

    Directory of Open Access Journals (Sweden)

    Novaković Tatjana B.

    2011-01-01

    Full Text Available Sintering and crystallization of low-density polyethylene glycol (PEG and lanthanum, La(III-doped Al2O3 aerogels prepared from aluminum isopropoxide were investigated. The sintering behavior of non-doped and doped aerogels was examined by following the change of specific surface area with isothermal heat-treatment. The specific surface area and crystalline phases of non-doped and PEG+La(III-doped aerogels were determined, and the effects of dopants on the sintering and crystallization of Al2O3 aerogels are discussed. Isothermal sintering experiments showed that the sintering mechanism of non-doped and PEG+La(III-doped Al2O3 aerogels is surface diffusion. The specific surface areas of alumina samples decrease rapidly during the initial period of sintering, and more slowly with prolonged sintering time. The change of the porous structure is correlated with the phase transformation of γ-Al2O3 during calcinations of Al2O3 aerogels. The surface area of non-doped Al2O3 aerogels came to about 20 m2g-1 with heat-treatment at 1100°C because of crystallization of α-Al2O3 after densification. In the case of heattreatment at 1200°C, the largest surface area was observed for PEG+La(III doped Al2O3 aerogels and the XRD pattern showed only low ordered θ-Al2O3. These indicate that the addition of PEG+La(III to boehmite sol prevents Al2O3 aerogels from sintering and crystallizing to the α-Al2O3 phase. Even after 20 h at 1000°C, PEG+La (III-doped alumina samples maintain a rather good specific surface area (108 m2 g-1 in comparison to the non-doped, containing mainly θ-Al2O3 and minor amounts of δ-Al2O3. Aluminum-oxides with these structural and textural properties are widely used as a coatings and catalyst supports in the field of various catalysis.

  5. Adsorption of titanium, chromium, and copper atoms on thin aluminum and magnesium oxide film surfaces

    Science.gov (United States)

    Tvauri, I. V.; Turiev, A. M.; Tsidaeva, N. I.; Gazzaeva, M. E.; Vladimirov, G. G.; Magkoev, T. T.

    2012-04-01

    Methods of Auger electron spectroscopy (AES), spectroscopy of characteristic electron energy losses (SCEEL), slow electron diffraction (SED), and contact potential difference (CPD) in ultrahigh vacuum are used to investigate the adsorption-emission properties and stability of two-component film systems formed by putting of Ti, Cr, and Cu atoms on MgO-Mo(011) and Al2O3-Mo(011) surfaces. All atoms have the properties of electronegative adsorbates. Continuous adatom monolayers are formed on the Al2O3-Mo(011) system surface, and three-dimensional islands are formed on the MgO-Mo(011) surface. The properties of monoatomic films on the oxide layer surface are close to those observed for bulk materials. No radical changes of the system properties are detected with increasing dielectric layer thickness. The thermal stability of the newly formed structures decreases in the order Ti, Cr, Cu, Al2O3(MgO), and Mo(011).

  6. Crystal orientation dependent thermoelectric properties of highly oriented aluminum-doped zinc oxide thin films

    KAUST Repository

    Abutaha, Anas I.

    2013-02-06

    We demonstrate that the thermoelectric properties of highly oriented Al-doped zinc oxide (AZO) thin films can be improved by controlling their crystal orientation. The crystal orientation of the AZO films was changed by changing the temperature of the laser deposition process on LaAlO3 (100) substrates. The change in surface termination of the LaAlO3 substrate with temperature induces a change in AZO film orientation. The anisotropic nature of electrical conductivity and Seebeck coefficient of the AZO films showed a favored thermoelectric performance in c-axis oriented films. These films gave the highest power factor of 0.26 W m−1 K−1 at 740 K.

  7. Novel nanoarray structures formed by template based approach: Characterization and electrochemistry

    Science.gov (United States)

    Alhoshan, Mansour Saleh

    Several different methods have been developed to form nanomaterials. The methods employed depend on the desired properties and applications. One of the broadest and important synthetic approaches for nanomaterials is based on templates. Templates provide a predetermined configuration or cast to guide the formation of nanomaterials with the desired morphology. They provide a very rich method to fabricate nanomaterials with a wide range of different morphologies and tunable sizes. After a materials formation reaction, the template can be sacrificially removed, leaving behind the final product that replicates the morphology of the original template. The synthetic methods based on templates overcome a weakness of other synthesis methods by providing good control of the final morphology of the produced nanomaterials. In addition, the methods are very general with respect to the types of materials that may be prepared. The main focus in this thesis is to produce highly ordered novel structures and arrays at nano/micro scales that are of electrochemical interest with good control of size and shape. Template-based approaches were used here to fabricate nano/micro tubes, rods, wires and porous films. By this approach, we incorporated electroless deposition and electrodeposition reactions with various templates, so that once the template is removed, the desired structures are reveled. Among the templates that were used are: track etched polycarbonate membrane, anodized aluminum oxide membrane and silica colloidal sphere. Electroless deposition and electrodeposition within the template to form nanomaterials is very attractive approach because it can be carried out under conditions mild enough to avoid any damage of both the desired materials and the template used. This approach makes possible the formation of a wide range of nanomaterials that may be useful technologically for catalytic, electronic, and energy storage applications. Examples of the nanostructures that were

  8. Research progress of the characteristics of oxidation reaction for nano-aluminum powders%纳米铝粉氧化反应特性研究进展

    Institute of Scientific and Technical Information of China (English)

    李鑫; 赵凤起; 徐司雨; 姚二岗; 安亭; 李猛; 巨荣辉

    2014-01-01

    纳米铝粉具有高的表面活性,在不同氧化剂中表现出不同的热反应性能,有必要对纳米铝粉在氧化剂中氧化反应特性作深入研究。详细综述了纳米铝粉在空气中的氧化反应特性,主要内容包括纳米铝粉室温Caberra-Mott氧化失活机理,纳米铝粉动态氧化过程3个阶段,纳米铝粉由相变和内外压差引起壳层破裂的点火燃烧机理;分析并比较了纳米铝粉动态氧化与点火燃烧之间的区别;讨论了纳米铝粉在水中低温与高温下的氧化反应特性,纳米铝粉在其他氧化剂中的氧化反应特性;指出纳米铝粉在不同氧化剂中氧化反应特性的研究方向;分析认为该研究不仅为纳米铝粉活性保护提供依据,而且对纳米铝粉在推进剂及炸药中的应用研究具有理论指导意义。%Nano-aluminum powders possess a high surface activity and exhibit different thermal reaction properties in different oxidants,so it is necessary to further study the thermal performance of nano-aluminum powders in different oxidation agents. The characteristics of oxidation reaction for nano-aluminum powders in the air were summarized in details,and the main contents are as follows:the mechanism of Caberra-Mott oxidation at room temperature,three stages of dynamic oxidation reaction,the mechanism of ignition and combustion caused by shell rupture due to phase transition or inner and outer pressure difference. The distinction be-tween dynamic oxidation reaction and the mechanism of ignition and combustion was analyzed and compared. The characteristics of oxidation reaction for nano-aluminum powders in water at low and high temperature as well as in other oxidants were discussed.It is believed that the study for oxidation reaction not only provides a basis for the protection of nano-aluminum powders,but has theoreti-cal significance for the application of nano-aluminum powders in propellants and explosives.

  9. Interstitial Oxide Ion Distribution and Transport Mechanism in Aluminum-Doped Neodymium Silicate Apatite Electrolytes.

    Science.gov (United States)

    An, Tao; Baikie, Tom; Orera, Alodia; Piltz, Ross O; Meven, Martin; Slater, Peter R; Wei, Jun; Sanjuán, María L; White, T J

    2016-04-01

    Rare earth silicate apatites are one-dimensional channel structures that show potential as electrolytes for solid oxide fuel cells (SOFC) due to their high ionic conductivity at intermediate temperatures (500-700 °C). This advantageous property can be attributed to the presence of both interstitial oxygen and cation vacancies, that create diffusion paths which computational studies suggest are less tortuous and have lower activation energies for migration than in stoichiometric compounds. In this work, neutron diffraction of Nd(28+x)/3AlxSi6-xO26 (0 ≤ x ≤ 1.5) single crystals identified the locations of oxygen interstitials, and allowed the deduction of a dual-path conduction mechanism that is a natural extension of the single-path sinusoidal channel trajectory arrived at through computation. This discovery provides the most thorough understanding of the O(2-) transport mechanism along the channels to date, clarifies the mode of interchannel motion, and presents a complete picture of O(2-) percolation through apatite. Previously reported crystallographic and conductivity measurements are re-examined in the light of these new findings. PMID:27015162

  10. Transparent resistive switching memory using aluminum oxide on a flexible substrate

    Science.gov (United States)

    Yeom, Seung-Won; Shin, Sang-Chul; Kim, Tan-Young; Ha, Hyeon Jun; Lee, Yun-Hi; Shim, Jae Won; Ju, Byeong-Kwon

    2016-02-01

    Resistive switching memory (ReRAM) has attracted much attention in recent times owing to its fast switching, simple structure, and non-volatility. Flexible and transparent electronic devices have also attracted considerable attention. We therefore fabricated an Al2O3-based ReRAM with transparent indium-zinc-oxide (IZO) electrodes on a flexible substrate. The device transmittance was found to be higher than 80% in the visible region (400-800 nm). Bended states (radius = 10 mm) of the device also did not affect the memory performance because of the flexibility of the two transparent IZO electrodes and the thin Al2O3 layer. The conduction mechanism of the resistive switching of our device was explained by ohmic conduction and a Poole-Frenkel emission model. The conduction mechanism was proved by oxygen vacancies in the Al2O3 layer, as analyzed by x-ray photoelectron spectroscopy analysis. These results encourage the application of ReRAM in flexible and transparent electronic devices.

  11. Catalytical oxidation of styrene by molecularly imprinted polymer with phenylacetic acid as template and hemin as co-monomer

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This letter used the molecular imprinting technology to build up the microenvironment around co-monomer hemin to mimic the cytochrome P450 catalyzing the epoxidation of styrene. The results showed that the conversion rates of products were obviously enhanced by molecularly imprinted polymers, compared to free hemin solution, using three kinds of oxidants. The used axial ligand in polymers synthesis also improved the total conversion rates.

  12. Template-Based Electrochemically Controlled Growth of Segmented Multimetal Nanorods

    Directory of Open Access Journals (Sweden)

    Mee Rahn Kim

    2010-01-01

    Full Text Available Multisegmented one-dimensional nanostructures composed of gold, copper, and nickel have been fabricated by depositing metals electrochemically in the pores of anodic aluminum oxide (AAO templates. The electrodeposition process has been carried out using a direct current in a two-electrode electrochemical cell, where a silver-evaporated AAO membrane and a platinum plate have served as a working electrode and a counter electrode, respectively. The striped multimetal rods with an average diameter of about 300 nm have tunable lengths ranging from a few hundred nanometers to a few micrometers. The lengths and the sequence of metal segments in a striped rod can be tailored readily by controlling the durations of electrodeposition and the order of electroplating solutions, respectively.

  13. Electrode patterning and annealing processes of aluminum-doped zinc oxide thin films using a UV laser system

    Science.gov (United States)

    Hsiao, Wen-Tse; Tseng, Shih-Feng; Huang, Kuo-Cheng; Chiang, Donyau

    2013-01-01

    This study presents the hybrid processing (patterning and annealing) of aluminum-doped zinc oxide (AZO) films in a one-step process using a diode-pumped-solid-state (DPSS) ultraviolet (UV) laser system. The focused laser beam had a diameter of 30 μm and the positive defocused laser beam had a diameter of 1 mm. Both beams were adjusted using a UV laser-processing system. AZO films were deposited on Corning Eagle 2000® optical glass sheets with a thickness of 0.7 mm using a sputtering method. The deposited films were approximately 200 nm. The optoelectronic properties of machined (patterning and annealing) AZO films depend on the laser pulse frequency and galvanometer scanning speed. The surface morphology, roughness, optical transmittance, and resistivity of the films after the laser patterning and annealing processes were measured using a three-dimensional confocal laser scanning microscope, a field emission scanning electron microscope (FE-SEM), a spectrophotometer, and a four-point probe instrument, respectively. Experimental results indicate that the ablation depth increased as the pulse repetition frequency increased. The ablation depth also decreased as the galvanometric scanning speed increased. The transmittance spectra of the film changes slightly after laser annealing, and the average transmittance in the visible region is approximately 83%. All resistivity values of laser-patterned and annealed AZO films decreased significantly. The structural properties grain size was calculated firm the X-ray diffraction (XRD) spectra using the Scherrer equation that increased from 7.4 nm to 12 nm as the annealing scanning speed decreased from 800 mm/s to 400 mm/s. The root mean square (RMS) values of annealed AZO films treated with a laser scanning speed of 500 mm/s with a pulse repetition frequency of 40 kHz, 55 kHz, and 70 kHz were 1.1 nm, 1.2 nm, and 1.8 nm, respectively.

  14. Control Preparation of Nano γ Phase Aluminum Oxide by Explosive Temperature%爆温控制合成γ型纳米氧化铝

    Institute of Scientific and Technical Information of China (English)

    李瑞勇; 李晓杰; 闫鸿浩

    2011-01-01

    本文旨在通过改变混合炸药的爆温来控制爆轰合成的纳米氧化铝的晶型.根据研究方案,采用600 g硝酸铝粉末和400 g炸药黑索金粉末为原材料,通过搅拌把两者均匀混合配制出混合炸药.经过计算该粉状混合炸药的理论爆温约为945℃,该温度接近于低温稳定的7型氧化铝生成和存在的温度区间,所以该混合炸药发生爆轰反应时应该产生γ型纳米氧化铝.为了验证理论分析,将该混合炸药放在直径为3 m的专用爆炸罐里面进行了爆轰反应实验.利用X射线衍射仪(XRD)和透射电子显微镜(TEM)对收集到的爆轰产物进行了检测.检测结果表明爆轰产物确实是y型纳米氧化铝,氧化铝颗粒为标准的球形,颗粒尺寸约为20 nm.因此,可以通过理论计算改变混合炸药的爆温来控制纳米氧化铝的晶型.%The phase of nano aluminum oxide prepared by detonation synthesis was controlled by changing the explosive temperature of the mixed explosion. According to the research scheme, the mixed explosion was made through uniformly mixing 600 g aluminum nitrate powder with 400 g explosive hexogen.The theoretical explosive temperature of the mixed explosion was 945 ℃ by theoretical calculation, which was close to the temperature interval of formation and existence of γ phase aluminum oxide. Therefore,nano γphase aluminum oxide should be prepared through detonation of the mixed explosion. In order to prove the theoretical presumption, detonation experiment was conducted in a special spherical tank with 3 m diameter and the explosion product was characterized by transmission electron microscope (TEM) and X-ray diffraction (XRD). The results indicate that the product is nano γ phase aluminum oxide actually and the granule of aluminum oxide is spherical, with the particle dimension of about 20 nm. It is thus verified that the phase of aluminum oxide can be controlled by changing the explosive temperature of the mixed

  15. 铝合金微弧氧化技术研究概况%Research situation of micro-arc oxidation of aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    石小超; 陈朝章; 徐晋勇; 高成; 王贵

    2012-01-01

    综述了铝合金微弧氧化技术的原理及陶瓷膜的特点.着重分析总结电流密度、电压与频率、占空比等电参量因素对陶瓷膜性能的影响,介绍铝合金微弧氧化中常用的电解液组成,简要描述微弧氧化陶瓷膜的硬度、耐磨、断裂、耐腐蚀等性能.%Treatment principle of aluminum alloy and the formation characteristics of the ceramic membrane by micro - arc oxidation (MAO) technique are reviewed. The effects of electrical parameters, such as current density, voltage and frequency, duty cycle on the performance of micro - arc oxidation ceramic coating are emphasized. Electrolyte composition of micro - arc oxidation on aluminum alloys is introduced. The hardness, wear resistance, fracture resistance, corrosion resistance and other properties of the micro-arc oxidation ceramic coating are briefly described.

  16. Aluminum Migration and Intrinsic Defect Interaction in Single-Crystal Zinc Oxide

    Science.gov (United States)

    Johansen, K. M.; Vines, L.; Bjørheim, T. S.; Schifano, R.; Svensson, B. G.

    2015-02-01

    Vacancy-mediated migration of Al in single-crystal zinc oxide (ZnO) is investigated using secondary-ion mass spectrometry (SIMS) combined with hybrid density-functional theory (DFT) calculations. A thin film of Al-doped ZnO is deposited by sputtering onto the single-crystal bulk material and heat treated at temperatures in the range of 900 °C - 1300 °C . The migration of Al is found to be Zn-vacancy mediated. In order to elucidate the physical processes involved, an alternative model based on reactive diffusion is developed. The model includes the time evolution of the concentration of Al atoms on the Zn site (AlZn ), Zn vacancies (vZn), and a complex between the two, where the influence of the charge state of vZn on its formation energy is incorporated through the free carrier concentration. The modeling results exhibit close agreement with the experimental data and the AlZnvZn complex is found to diffuse with an activation energy of 2.6 eV and a preexponential factor of 4 ×10-2 cm2 s-1 . The model is supported by the results from hybrid DFT calculations combined with thermodynamical modeling, which also suggest that a complex between AlZn and vZn is promoted in n -doped material. The charge state of this complex is effectively -1 , and it thus acts as a compensating acceptor, limiting full utilization of the shallow AlZn donor. Furthermore, the DFT calculations also predict a high formation energy for both substitutional Al on the O site (AlO ) and interstitial Al (Ali), and are therefore of minor importance for Al migration in ZnO. The close coupling between the hybrid DFT calculations and the developed diffusion model enable benchmarking of the accuracy of several parameters extracted from the DFT calculations. Furthermore, since the diffusion model hinges strongly on defect concentrations, it couples directly to results from measurements by other experimental techniques than those used in this paper and provides an opportunity for independent verification

  17. Metal Ion Imbalance-Related Oxidative Stress Is Involved in the Mechanisms of Liver Injury in a Rat Model of Chronic Aluminum Exposure.

    Science.gov (United States)

    Yang, Yang; Wang, Hong; Guo, Yuanxin; Lei, Wenjuan; Wang, Jianfeng; Hu, Xinyue; Yang, Junqing; He, Qin

    2016-09-01

    The objective of the study is to investigate the effects of chronic aluminum overload on rat liver function and its induction of pathological changes in metal ion levels and oxidative stress in hepatic tissues. Wistar rats were intragastrically administered aluminum gluconate (200 mg Al(3+)/Kg) once a day, 5 days a week, for 20 weeks. HE staining was used to visualize pathological changes in rat liver tissue. A biochemical method was adopted to detect ALT, AST, ALP, and GGT levels, as well as liver SOD activity and blood plasma MDA content. A plasma atomic emission spectrophotometer was used to detect Al, Mn, Fe, Zn, and Cu ion contents in liver tissue. Our results showed obvious vacuolar degeneration, granular degeneration, and spotty necrosis in chronic Al-overload rat hepatocytes. The levels of ALT, AST, ALP, and GGT were significantly increased. Liver SOD activity was significantly decreased, and MDA content was significantly increased. In Al-overload rat liver, Al, Mn, Fe, and Cu contents were significantly increased, and in Al-overload rat serum, Mn, Fe, Zn, and Cu contents were significantly decreased. However, the Al level in Al-overload rat serum was not significantly different from that in control rat serum. These results suggest that chronic aluminum overload causes obvious damage to rat liver and causes imbalances in Al, Mn, Fe, Zn, and Cu levels in rat liver and serum. Metal ion imbalance-related oxidative stress may be involved in the mechanism of chronic liver injury caused by aluminum overload. PMID:26811106

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. Template-assisted synthesis of III-nitride and metal-oxide nano-heterostructures using low-temperature atomic layer deposition for energy, sensing, and catalysis applications (Presentation Recording)

    Science.gov (United States)

    Biyikli, Necmi; Ozgit-Akgun, Cagla; Eren, Hamit; Haider, Ali; Uyar, Tamer; Kayaci, Fatma; Guler, Mustafa Ozgur; Garifullin, Ruslan; Okyay, Ali K.; Ulusoy, Gamze M.; Goldenberg, Eda

    2015-08-01

    Recent experimental research efforts on developing functional nanostructured III-nitride and metal-oxide materials via low-temperature atomic layer deposition (ALD) will be reviewed. Ultimate conformality, a unique propoerty of ALD process, is utilized to fabricate core-shell and hollow tubular nanostructures on various nano-templates including electrospun nanofibrous polymers, self-assembled peptide nanofibers, metallic nanowires, and multi-wall carbon nanotubes (MWCNTs). III-nitride and metal-oxide coatings were deposited on these nano-templates via thermal and plasma-enhanced ALD processes with thickness values ranging from a few mono-layers to 40 nm. Metal-oxide materials studied include ZnO, TiO2, HfO2, ZrO2, and Al2O3. Standard ALD growth recipes were modified so that precursor molecules have enough time to diffuse and penetrate within the layers/pores of the nano-template material. As a result, uniform and conformal coatings on high-surface area nano-templates were demonstrated. Substrate temperatures were kept below 200C and within the self-limiting ALD window, so that temperature-sensitive template materials preserved their integrity III-nitride coatings were applied to similar nano-templates via plasma-enhanced ALD (PEALD) technique. AlN, GaN, and InN thin-film coating recipes were optimized to achieve self-limiting growth with deposition temperatures as low as 100C. BN growth took place only for >350C, in which precursor decomposition occured and therefore growth proceeded in CVD regime. III-nitride core-shell and hollow tubular single and multi-layered nanostructures were fabricated. The resulting metal-oxide and III-nitride core-shell and hollow nano-tubular structures were used for photocatalysis, dye sensitized solar cell (DSSC), energy storage and chemical sensing applications. Significantly enhanced catalysis, solar efficiency, charge capacity and sensitivity performance are reported. Moreover, core-shell metal-oxide and III-nitride materials

  20. Code Generation with Templates

    CERN Document Server

    Arnoldus, Jeroen; Serebrenik, A

    2012-01-01

    Templates are used to generate all kinds of text, including computer code. The last decade, the use of templates gained a lot of popularity due to the increase of dynamic web applications. Templates are a tool for programmers, and implementations of template engines are most times based on practical experience rather than based on a theoretical background. This book reveals the mathematical background of templates and shows interesting findings for improving the practical use of templates. First, a framework to determine the necessary computational power for the template metalanguage is presen

  1. Synthesis of titanium oxide nanoparticles using DNA-complex as template for solution-processable hybrid dielectric composites

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, J.C. [Center for Sustainable Materials Chemistry, 153 Gilbert Hall, Oregon State University, Corvallis, OR (United States); Mejia, I.; Murphy, J.; Quevedo, M. [Department of Materials Science and Engineering, University of Texas at Dallas, Dallas, TX (United States); Garcia, P.; Martinez, C.A. [Engineering and Technology Institute, Autonomous University of Ciudad Juarez, Ciudad Juarez, Chihuahua (Mexico)

    2015-09-15

    Highlights: • We developed a synthesis method to produce TiO{sub 2} nanoparticles using a DNA complex. • The nanoparticles were anatase phase (~6 nm diameter), and stable in alcohols. • Composites showed a k of 13.4, 4.6 times larger than the k of polycarbonate. • Maximum processing temperature was 90 °C. • Low temperature enables their use in low-voltage, low-cost, flexible electronics. - Abstract: We report the synthesis of TiO{sub 2} nanoparticles prepared by the hydrolysis of titanium isopropoxide (TTIP) in the presence of a DNA complex for solution processable dielectric composites. The nanoparticles were incorporated as fillers in polycarbonate at low concentrations (1.5, 5 and 7 wt%) to produce hybrid dielectric films with dielectric constant higher than thermally grown silicon oxide. It was found that the DNA complex plays an important role as capping agent in the formation and suspension stability of nanocrystalline anatase phase TiO{sub 2} at room temperature with uniform size (∼6 nm) and narrow distribution. The effective dielectric constant of spin-cast polycarbonate thin-films increased from 2.84 to 13.43 with the incorporation of TiO{sub 2} nanoparticles into the polymer host. These composites can be solution processed with a maximum temperature of 90 °C and could be potential candidates for its application in low-cost macro-electronics.

  2. DUPLEX Al2O3/DLC COATING ON 15SiCp/2024 ALUMINUM MATRIX COMPOSITE USING COMBINED MICROARC OXIDATION AND FILTERED CATHODIC VACUUM ARC DEPOSITION

    OpenAIRE

    WENBIN XUE; HUA TIAN; JIANCHENG DU; MING HUA; XU ZHANG; YONGLIANG LI

    2012-01-01

    Microarc oxidation (MAO) treatment produces a thick Al2O3 coating on the 15SiCp/2024 aluminum matrix composite. After pretreatment of Ti ion implantation, a thin diamond-like carbon film (DLC) was deposited on the top of polished Al2O3 coating by a pulsed filtered cathodic vacuum arc (FCVA) deposition system with a metal vapor vacuum arc (MEVVA) source. The morphology and tribological properties of the duplex Al2O3/DLC multiplayer coating were investigated by Raman spectroscopy, scanning elec...

  3. Study on Light Extraction from GaN-based Green Light-Emitting Diodes Using Anodic Aluminum Oxide Pattern and Nanoimprint Lithography

    OpenAIRE

    Shengxiang Jiang; Yulong Feng; Zhizhong Chen; Lisheng Zhang; Xianzhe Jiang; Qianqian Jiao; Junze Li; Yifan Chen; Dongsan Li; Lijian Liu; Tongjun Yu; Bo Shen; Guoyi Zhang

    2016-01-01

    An anodic aluminum oxide (AAO) patterned sapphire substrate, with the lattice constant of 520 ± 40 nm, pore dimension of 375 ± 50 nm, and height of 450 ± 25 nm was firstly used as a nanoimprint lithography (NIL) stamp and imprinted onto the surface of the green light-emitting diode (LED). A significant light extraction efficiency (LEE) was improved by 116% in comparison to that of the planar LED. A uniform broad protrusion in the central area and some sharp lobes were also obtained in the ang...

  4. Low temperature solid oxide fuel cells with proton-conducting Y:BaZrO3 electrolyte on porous anodic aluminum oxide substrate

    International Nuclear Information System (INIS)

    This paper presents the architecture of a nano thin-film yttrium-doped barium zirconate (BYZ) solid-oxide fuel cell that uses nanoporous anodic aluminum oxide (AAO) as a supporting and gas-permeable substrate. The anode was fabricated by sputtering 300 nm platinum thin film that partially covered the AAO surface pores, followed by an additional conformal platinum coating to tune the pore size by atomic layer deposition. Two different nano-porous anode structures with a pore size of 10 nm or 50 nm were deposited. Proton-conducting BYZ ceramic electrolyte with increasing thicknesses of 300, 600, and 900 nm was deposited on top of the platinum anode by pulsed laser deposition, followed by a 200 nm layer of porous Pt sputtered on BYZ electrolyte as a cathode. The open circuit voltage (OCV) of the fuel cells was characterized at 250 °C with 1:1 volumetric stoichiometry of a methanol/water vapor mixture as the fuel. The OCVs were 0.17 V with a 900 nm-thick BYZ electrolyte on 50 nm pores and 0.3 V with a 600 nm-thick BYZ electrolyte on 10 nm pores, respectively, but it increased to 0.8 V for a 900 nm-thick BYZ electrolyte on 10 nm pores, indicating that increasing the film thickness and decreasing a surface pore size help to reduce the number of electrolyte pinholes and the gas leakage through the electrolyte. A maximum power density of 5.6 mW/cm2 at 250 °C was obtained from the fuel cell with 900 nm of BYZ electrolyte using methanol vapor as a fuel. - Highlights: • A low temperature ceramic fuel cell on nano-porous substrate was demonstrated. • A thin-film yttrium doped barium zirconate (BYZ) was deposited as an electrolyte. • An open circuit voltage (OCV) was measured to verify the BYZ film quality. • An OCV increased by increasing BYZ film thickness and decreasing pore size of anode. • The current–voltage performance was measured using vaporized methanol fuel at 250 °C

  5. Low temperature solid oxide fuel cells with proton-conducting Y:BaZrO{sub 3} electrolyte on porous anodic aluminum oxide substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Seungbum [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); School of Mechanical and Aerospace Engineering, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151–742 (Korea, Republic of); Su, Pei-Chen [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Ji, Sanghoon [Graduate School of Convergence Science and Technology, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151–742 (Korea, Republic of); Cha, Suk Won, E-mail: swcha@snu.ac.kr [School of Mechanical and Aerospace Engineering, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151–742 (Korea, Republic of)

    2013-10-01

    This paper presents the architecture of a nano thin-film yttrium-doped barium zirconate (BYZ) solid-oxide fuel cell that uses nanoporous anodic aluminum oxide (AAO) as a supporting and gas-permeable substrate. The anode was fabricated by sputtering 300 nm platinum thin film that partially covered the AAO surface pores, followed by an additional conformal platinum coating to tune the pore size by atomic layer deposition. Two different nano-porous anode structures with a pore size of 10 nm or 50 nm were deposited. Proton-conducting BYZ ceramic electrolyte with increasing thicknesses of 300, 600, and 900 nm was deposited on top of the platinum anode by pulsed laser deposition, followed by a 200 nm layer of porous Pt sputtered on BYZ electrolyte as a cathode. The open circuit voltage (OCV) of the fuel cells was characterized at 250 °C with 1:1 volumetric stoichiometry of a methanol/water vapor mixture as the fuel. The OCVs were 0.17 V with a 900 nm-thick BYZ electrolyte on 50 nm pores and 0.3 V with a 600 nm-thick BYZ electrolyte on 10 nm pores, respectively, but it increased to 0.8 V for a 900 nm-thick BYZ electrolyte on 10 nm pores, indicating that increasing the film thickness and decreasing a surface pore size help to reduce the number of electrolyte pinholes and the gas leakage through the electrolyte. A maximum power density of 5.6 mW/cm{sup 2} at 250 °C was obtained from the fuel cell with 900 nm of BYZ electrolyte using methanol vapor as a fuel. - Highlights: • A low temperature ceramic fuel cell on nano-porous substrate was demonstrated. • A thin-film yttrium doped barium zirconate (BYZ) was deposited as an electrolyte. • An open circuit voltage (OCV) was measured to verify the BYZ film quality. • An OCV increased by increasing BYZ film thickness and decreasing pore size of anode. • The current–voltage performance was measured using vaporized methanol fuel at 250 °C.

  6. Dispersion fraction enhances cellular growth of carbon nanotube and aluminum oxide reinforced ultrahigh molecular weight polyethylene biocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Anup Kumar; Balani, Kantesh, E-mail: kbalani@iitk.ac.in

    2015-01-01

    Ultrahigh molecular weight polyethylene (UHMWPE) is widely used as bone-replacement material for articulating surfaces due to its excellent wear resistance and low coefficient of friction. But, the wear debris, generated during abrasion between mating surfaces, leads to aseptic loosening of implants. Thus, various reinforcing agents are generally utilized, which may alter the surface and biological properties of UHMWPE. In the current work, the cellular response of compression molded UHMWPE upon reinforcement of bioactive multiwalled carbon nanotubes (MWCNTs) and bioinert aluminum oxide (Al{sub 2}O{sub 3}) is investigated. The phase retention and stability were observed using X-ray diffraction, Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The reinforcement of MWCNTs and Al{sub 2}O{sub 3} has shown to alter the wettability (from contact angle of ∼ 88° ± 2° to ∼ 118° ± 4°) and surface energy (from ∼ 23.20 to ∼ 17.75 mN/m) of composites with respect to UHMWPE, without eliciting any adverse effect on cytocompatibility for the L929 mouse fibroblast cell line. Interestingly, the cellular growth of the L929 mouse fibroblast cell line is observed to be dominated by the dispersion fraction of surface free energy (SFE). After 48 h of incubation period, a decrease in metabolic activity of MWCNT–Al{sub 2}O{sub 3} reinforced composites is attributed to apatite formation that reduces the dispersion fraction of surface energy. The mineralized apatite during incubation was confirmed and quantified by energy dispersive spectroscopy and X-ray diffraction respectively. Thus, the dispersion fraction of surface free energy can be engineered to play an important role in achieving enhanced metabolic activity of the MWCNT–Al{sub 2}O{sub 3} reinforced UHMWPE biopolymer composites. - Highlights: • The cellular response of UHMWPE upon MWCNT and Al{sub 2}O{sub 3} reinforcement is highlighted. • Wettability decreases with Al{sub 2}O{sub 3} and

  7. High-temperature CO2 capture cycles of hydrated limestone prepared with aluminum (hydr)oxides derived from kaolin

    International Nuclear Information System (INIS)

    Highlights: • Hydrated limestone exhibited a higher reactivity and stability. • Microstructure of hydrated limestone was significantly improved. • Hydrated limestone still suffered less loss-incapacity. • Hydrated limestone sorbents with kaolin-based binders were prepared and characterized. • Sorbents prepared from hydrated limestone and Al(OH)3 binder are a promising sorbent. - Abstract: A simple and convenient process was used to improve the utilization of natural limestone and kaolin for calcium looping technology and environmental applications. The calcined natural limestone modified with the distilled water (denoted as Limestone-W), was systematically studied and compared with the other CaO sorbents (calcium acetate, calcium D-gluconate and calcined natural limestone). These CaO-based sorbents were tested for their CO2 capture behavior through 20 carbonation/calcination cycles in a thermo-gravimetric analyzer (TGA). Their morphology, pore structure and phase composition before and after carbonation/calcination cycles were determined by scanning electron microscopy, nitrogen adsorption, and X-ray diffraction. The first-cycle and multicycle sorption results revealed that the Limestone-W sorbent exhibited a relatively faster reaction rate and higher cyclic CO2 capture. The characterization data indicated that the Limestone-W was composed of a special calcium oxide structure with lower crystalline and higher porosity nanoparticles, which appeared to be the main reasons for its higher CO2 capture capability. However, the Limestone-W still suffered loss of reactivity, even though it was less pronounced than the other CaO sorbent. To avoid this unfavorable effect, a thermally stable inert material (aluminum hydroxide derived from kaolin) was incorporated into the Limestone-W structure. This new sorbent revealed higher stability because the formation of a stable framework of Ca12Al14O33 particles hindered densification and sintering of the CaO phase. It was

  8. Investigation of the weldability of iron-aluminum-chromium overlay coatings for corrosion protection in oxidizing/sulfidizing environments

    Science.gov (United States)

    Regina, Jonathan R.

    The current study investigated the effect of chromium additions on the hydrogen cracking susceptibility of Fe-Al weld overlay claddings containing chromium additions. It was found that the weldability of FeAlCr claddings was a function of both the aluminum and chromium concentrations of the weld coatings. Weld overlay compositions that were not susceptible to hydrogen cracking were identified and the underlying mechanism behind the hydrogen cracking phenomenon was investigated further. It was concluded that the cracking behavior of the FeAlCr welds depended strongly on the microstructure of the weld fusion zone. Although it was found that the cracking susceptibility was influenced by the presence of Fe-Al intermetallic phases (namely Fe3 Al and FeAl), the cracking behavior of FeAlCr weld overlay claddings also depended on the size and distribution of carbide and oxide particles present within the weld structure. These particles acted as hydrogen trapping sites, which are areas where free hydrogen segregates and can no longer contribute to the hydrogen embrittlement of the metal. It was determined that in practical applications of these FeAlCr weld overlay coatings, carbon should be present within these welds to reduce the amount of hydrogen available for hydrogen cracking. Based on the weldability results of the FeAlCr weld claddings, coating compositions that were able to be deposited crack-free were used for long-term corrosion testing in a simulated low NOx environment. These alloys were compared to a Ni-based superalloy (622), which is commonly utilized as boiler tube coatings in power plant furnaces for corrosion protection. It was found that the FeAlCr alloys demonstrated superior corrosion resistance when compared to the Ni-based superalloy. Due to the excellent long-term corrosion behavior of FeAlCr weld overlays that were immune to hydrogen cracking, it was concluded that select FeAlCr weld overlay compositions would make excellent corrosion resistant

  9. Efficient indium-tin-oxide free inverted organic solar cells based on aluminum-doped zinc oxide cathode and low-temperature aqueous solution processed zinc oxide electron extraction layer

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Dazheng; Zhang, Chunfu, E-mail: cfzhang@xidian.edu.cn; Wang, Zhizhe; Zhang, Jincheng; Tang, Shi; Wei, Wei; Sun, Li; Hao, Yue, E-mail: yhao@xidian.edu.cn [State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, No. 2 South Taibai Road, Xi' an 710071 (China)

    2014-06-16

    Indium-tin-oxide (ITO) free inverted organic solar cells (IOSCs) based on aluminum-doped zinc oxide (AZO) cathode, low-temperature aqueous solution processed zinc oxide (ZnO) electron extraction layer, and poly(3-hexylthiophene-2, 5-diyl):[6, 6]-phenyl C{sub 61} butyric acid methyl ester blend were realized in this work. The resulted IOSC with ZnO annealed at 150 °C shows the superior power conversion efficiency (PCE) of 3.01%, if decreasing the ZnO annealing temperature to 100 °C, the obtained IOSC also shows a PCE of 2.76%, and no light soaking issue is observed. It is found that this ZnO film not only acts as an effective buffer layer but also slightly improves the optical transmittance of AZO substrates. Further, despite the relatively inferior air-stability, these un-encapsulated AZO/ZnO IOSCs show comparable PCEs to the referenced ITO/ZnO IOSCs, which demonstrates that the AZO cathode is a potential alternative to ITO in IOSCs. Meanwhile, this simple ZnO process is compatible with large area deposition and plastic substrates, and is promising to be widely used in IOSCs and other relative fields.

  10. The fabrication of short metallic nanotubes by templated electrodeposition

    Science.gov (United States)

    Huang, Chienwen; Hao, Yaowu

    2009-11-01

    Template-based electrochemical synthesis has widely been used to produce metal nanowires and nanorods. Commercially available filtration membranes, such as anodic aluminum oxide (AAO) and polycarbonate track etch membranes, have commonly been utilized as hard templates for this purpose. In this process, a thick metal film is usually sputtered or vacuum evaporated onto one side of the membrane to block the pores and serve as the working electrode for the subsequent electrodeposition. Here, we show that during the deposition of the metal electrode for AAO membranes, the electrode metal diffuses into the pores and is deposited on the pore walls which leads to preferential electrodeposition of metal on the walls and therefore forms metal tubes. This phenomenon has been utilized to fabricate short nanotubes by carefully controlling the electrodeposition conditions. The process is a straightforward method for any electroplatable materials to form nanoscale tubular structures. The effects of working electrodes and electrodeposition conditions on the formation of tubular structures are discussed in detail. A new mechanism based on this simple fact is proposed to explain the formation of Ni tubes by Ni-Cu co-deposition. Also, we demonstrate how to distinguish magnetic nanotubes from nanorods by a simple magnetic measurement.

  11. NaCl盐膜对铝青铜高温氧化行为的影响%Effect of NaCl Film on Oxidation Behavior of Aluminum Bronze at High Temperature

    Institute of Scientific and Technical Information of China (English)

    李占鑫

    2009-01-01

    采用金相检验、X射线衍射、扫描电镜/能谱及热重分析法研究了涂有NaCl盐膜的铝青铜在700~900℃的氧化行为.结果表明,在NaCl盐膜的作用下,铝青铜中的铝较铜先腐蚀,所形成的氧化膜结构疏松,易开裂和剥落,从而加速铝的氧化过程.此外,还讨论了NaCl加速铝青铜氧化的机制.%The oxidation behavior of aluminum bronze coated with a NaCl film was studied by means of metallosco-py,XRD,SEM/EDS and thermogravimetry. The results show that because of the effect of NaCl film the aluminum will be eroded earlier than the copper in aluminum bronze and the oxide film produced will be loose and easy to crack and spall, with the oxidation of aluminum bronze accelerated. In addition, the mechanism for NaCl film to ac-celerate the oxidation of aluminum bronze was discussed, too.

  12. Impact of ribs on flow parameters and laminar heat transfer of water–aluminum oxide nanofluid with different nanoparticle volume fractions in a three-dimensional rectangular microchannel

    Directory of Open Access Journals (Sweden)

    Omid Ali Akbari

    2015-11-01

    Full Text Available This article aims to study the impact of ribs on flow parameters and laminar heat transfer of water–aluminum oxide nanofluid with different nanoparticle volume fractions in a three-dimensional rectangular microchannel. To this aim, compulsory convection heat transfer of water–aluminum oxide nanofluid in a rib-roughened microchannel has been numerically studied. The results of this simulation for rib-roughened three-dimensional microchannel have been evaluated in contrast to the smooth (unribbed three-dimensional microchannel with identical geometrical and heat–fluid boundary conditions. Numerical simulation is performed for different nanoparticle volume fractions for Reynolds numbers of 10 and 100. Cold fluid entering the microchannel is heated in order to apply constant flux to external surface of the microchannel walls and then leaves it. Given the results, the fluid has a higher heat transfer with a hot wall in surfaces with ribs rather than in smooth ones. As Reynolds number, number of ribs, and nanoparticle volume fractions increase, more temperature increase happens in fluid in exit intersection of the microchannel. By investigating Nusselt number and friction factor, it is observed that increase in nanoparticle volume fractions causes nanofluid heat transfer properties to have a higher heat transfer and friction factor compared to the base fluid used in cooling due to an increase in viscosity.

  13. Nanoporous anodic aluminum oxide with a long-range order and tunable cell sizes by phosphoric acid anodization on pre-patterned substrates

    Science.gov (United States)

    Surawathanawises, Krissada; Cheng, Xuanhong

    2014-01-01

    Nanoporous anodic aluminum oxide (AAO) has been explored for various applications due to its regular cell arrangement and relatively easy fabrication processes. However, conventional two-step anodization based on self-organization only allows the fabrication of a few discrete cell sizes and formation of small domains of hexagonally packed pores. Recent efforts to pre-pattern aluminum followed with anodization significantly improve the regularity and available pore geometries in AAO, while systematic study of the anodization condition, especially the impact of acid composition on pore formation guided by nanoindentation is still lacking. In this work, we pre-patterned aluminium thin films using ordered monolayers of silica beads and formed porous AAO in a single-step anodization in phosphoric acid. Controllable cell sizes ranging from 280 nm to 760 nm were obtained, matching the diameters of the silica nanobead molds used. This range of cell size is significantly greater than what has been reported for AAO formed in phosphoric acid in the literature. In addition, the relationships between the acid concentration, cell size, pore size, anodization voltage and film growth rate were studied quantitatively. The results are consistent with the theory of oxide formation through an electrochemical reaction. Not only does this study provide useful operational conditions of nanoindentation induced anodization in phosphoric acid, it also generates significant information for fundamental understanding of AAO formation. PMID:24535886

  14. Nanoporous anodic aluminum oxide with a long-range order and tunable cell sizes by phosphoric acid anodization on pre-patterned substrates.

    Science.gov (United States)

    Surawathanawises, Krissada; Cheng, Xuanhong

    2014-01-20

    Nanoporous anodic aluminum oxide (AAO) has been explored for various applications due to its regular cell arrangement and relatively easy fabrication processes. However, conventional two-step anodization based on self-organization only allows the fabrication of a few discrete cell sizes and formation of small domains of hexagonally packed pores. Recent efforts to pre-pattern aluminum followed with anodization significantly improve the regularity and available pore geometries in AAO, while systematic study of the anodization condition, especially the impact of acid composition on pore formation guided by nanoindentation is still lacking. In this work, we pre-patterned aluminium thin films using ordered monolayers of silica beads and formed porous AAO in a single-step anodization in phosphoric acid. Controllable cell sizes ranging from 280 nm to 760 nm were obtained, matching the diameters of the silica nanobead molds used. This range of cell size is significantly greater than what has been reported for AAO formed in phosphoric acid in the literature. In addition, the relationships between the acid concentration, cell size, pore size, anodization voltage and film growth rate were studied quantitatively. The results are consistent with the theory of oxide formation through an electrochemical reaction. Not only does this study provide useful operational conditions of nanoindentation induced anodization in phosphoric acid, it also generates significant information for fundamental understanding of AAO formation.

  15. RJS Templates for Rails

    CERN Document Server

    Fauser, Cody

    2006-01-01

    RJS templates are an exciting and powerful new type of template added to Rails 1.1. Unlike conventional Rails templates that generate HTML or XML, RJS templates generate JavaScript code that is executed when it is returned to the browser. This JavaScript generation allows you to perform multiple page updates in-place without a page reload using Ajax. All the JavaScript you need is generated from simple templates written in Ruby. This document helps you get acquainted with how RJS templates fit into the Rails framework and gets you started with a few easy-to-follow examples.

  16. Evidências da formação de monocamada de óxido de alumínio sobre sílica, através de reações de enxerto Evidence of aluminum oxide monolayer formation on a silica gel surface using grafting reactions

    Directory of Open Access Journals (Sweden)

    Julia M. D. Cónsul

    2005-06-01

    Full Text Available Aluminum oxide was dispersed on a commercial silica gel surface, using successive grafting reactions. The reaction products were characterized by N2 adsorption-desorption isotherms, scanning electron microscopy and infrared spectroscopy. The progressive incorporation of aluminum, up to 5.5% (w/w, does not produce agglomeration of alumina, since changes in the original pore size distribution of the silica matrix were not observed. The aluminum oxide covers homogeneously the silica surface.

  17. Influence of pulsed mechanical activation of hematite-graphite-aluminum powder mixtures on the reduction of iron oxides

    Science.gov (United States)

    Bodrova, L. E.; Vatolin, N. A.; Pastukhov, E. A.; Petrova, S. A.; Popova, E. A.; Zakharov, R. G.

    2011-11-01

    To decrease the temperature of direct iron reduction by carbon and aluminum, short-term pulsed mechanical activation (PMA) of an Fe2O3 + Cgr + Al powder mixture is perfumed during sound-frequency shock loading by a flat activating plunger. The PMA efficiency for powders in comparable with mechanical activation in high-energy ball mills in a decrease in the activation time and retaining the chemical purity of a powder composition.

  18. Modeling and Predicting the Effect of Surface Oxidation on the Normal Spectral Emissivity of Aluminum 5052 at 800 K to 910 K

    Science.gov (United States)

    Shi, Deheng; Zou, Fenghui; Zhu, Zunlue; Sun, Jinfeng

    2016-01-01

    In this study, we tried to develop a model to predict the effect of surface oxidization on the normal spectral emissivity of aluminum 5052 at a temperature range of 800 to 910 K and wavelength of 1.5 \\upmu m. In experiments, specimens were heated in air for 6 h at certain temperatures. Two platinum-rhodium thermocouples were symmetrically welded onto the front surface of the specimens near the measuring area for accurate monitoring of the temperature at the specimen surface. The temperatures measured by the two thermocouples had an uncertainty of 1 K. The normal spectral emissivity values were measured over the 6-h heating period at temperatures from 800 K to 910 K in increments of 10 K. Strong oscillations in the normal spectral emissivity were observed at each temperature. These oscillations were determined to form by the interference between the radiation stemming from the oxide layer and radiation from the substrate. The present measurements were compared with previous experimental results, and the variation in the normal spectral emissivity at given temperatures was evaluated. The uncertainty of the normal spectral emissivity caused only by the surface oxidization was found to be approximately 12.1 % to 21.8 %, and the corresponding uncertainty in the temperature caused only by the surface oxidization was approximately 9.1 K to 15.2 K. The model can reproduce the normal spectral emissivity well, including the strong oscillations that occur during the initial heating period.

  19. Decontamination of discharged aluminum brass condenser tubes of a BWR. Evolving the chemical formulation for copper oxide dissolution

    International Nuclear Information System (INIS)

    Chemical formulations for copper oxide dissolution have been evaluated primarily for the minimum ionic load resulting in the spent formulation along with other desirable qualities. Peroxydisulfuric acid prepared freshly through ion exchange route has shown almost stoichiometric dissolution of the copper oxide as per the acidic oxidative action with efficient kinetics. Stability of the prepared formulation for its application and its effective oxidizing behaviour and aqueous cupric ion stabilizing by its redox product has been established experimentally. (author)

  20. Duplex Al2O3/DLC Coating on 15SiCp/2024 Aluminum Matrix Composite Using Combined Microarc Oxidation and Filtered Cathodic Vacuum Arc Deposition

    Science.gov (United States)

    Xue, Wenbin; Tian, Hua; Du, Jiancheng; Hua, Ming; Zhang, Xu; Li, Yongliang

    2012-08-01

    Microarc oxidation (MAO) treatment produces a thick Al2O3 coating on the 15SiCp/2024 aluminum matrix composite. After pretreatment of Ti ion implantation, a thin diamond-like carbon film (DLC) was deposited on the top of polished Al2O3 coating by a pulsed filtered cathodic vacuum arc (FCVA) deposition system with a metal vapor vacuum arc (MEVVA) source. The morphology and tribological properties of the duplex Al2O3/DLC multiplayer coating were investigated by Raman spectroscopy, scanning electron microscopy (SEM) and SRV ball-on-disk friction tester. It is found that the duplex Al2O3/DLC coating had good adhesion and a low friction coefficient of less than 0.07. As compared to a single Al2O3 or DLC coating, the duplex Al2O3/DLC coating on aluminum matrix composite exhibited a better wear resistance against ZrO2 ball under dry sliding, because the Al2O3 coating as an intermediate layer improved load support for the top DLC coating on 15SiCp/2024 composite substrate, meanwhile the top DLC coating displayed low friction coefficient.

  1. Enhanced Efficiency of GaAs Single-Junction Solar Cells with Inverted-Cone-Shaped Nanoholes Fabricated Using Anodic Aluminum Oxide Masks

    Directory of Open Access Journals (Sweden)

    Kangho Kim

    2013-01-01

    Full Text Available The GaAs solar cells are grown by low-pressure metalorganic chemical vapor deposition (LP-MOCVD and fabricated by photolithography, metal evaporation, annealing, and wet chemical etch processes. Anodized aluminum oxide (AAO masks are prepared from an aluminum foil by a two-step anodization method. Inductively coupled plasma dry etching is used to etch and define the nanoarray structures on top of an InGaP window layer of the GaAs solar cells. The inverted-cone-shaped nanoholes with a surface diameter of about 50 nm are formed on the top surface of the solar cells after the AAO mask removal. Photovoltaic and optical characteristics of the GaAs solar cells with and without the nanohole arrays are investigated. The reflectance of the AAO nanopatterned samples is lower than that of the planar GaAs solar cell in the measured range. The short-circuit current density increased up to 11.63% and the conversion efficiency improved from 10.53 to 11.57% under 1-sun AM 1.5 G conditions by using the nanohole arrays. Dependence of the efficiency enhancement on the etching depth of the nanohole arrays is also investigated. These results show that the nanohole arrays fabricated with an AAO technique may be employed to improve the light absorption and, in turn, the conversion efficiency of the GaAs solar cell.

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

    Science.gov (United States)

    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.

  3. COPOLYMERIZATION OF CARBON DIOXIDE AND CYCLOHEXENE OXIDE CATALYZED BY ALUMINUM PORPHYRIN-QUATERNARY AMMONIUM SALT IN THE PRESENCE OF BULKY LEWIS ACID

    Institute of Scientific and Technical Information of China (English)

    Yu-sheng Qin; Xian-hong Wang; Xiao-jiang Zhao; Fo-song Wang

    2008-01-01

    Chloro(5,10,15,20-tetraphenyl-porphyrinato)-aluminum/tetraethylammonium bromide (Et4NBr) in combinationwith bulky Lewis acid was used for the copolymerization of CO2 and cyclohexene oxide (CHO). Bulky Lewis acid havingsubstituents at the ortho positions of the phenolate ligands, like methylaluminum bis(2,6-di-tert-butyl-4-methylphenolate),significantly shortened the induction period and raised the catalytic activity, the corresponding turnover frequency reached44.9 h-1 in 9 h, which was 23.8% higher than that from (TPP)AICI/EtaNBr binary catalyst. The resulting polycarbonate hascarbonate linkage over 93% with number average molecular weight of (4.5-6.5)×103 and polydispersity index below 1.10.

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

    Directory of Open Access Journals (Sweden)

    Aschalew Kassu

    2015-11-01

    Full Text Available 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.

  5. Effect of Al2O3 Micro-powder Additives on the Properties of Micro-arc Oxidation Coatings Formed on 6061 Aluminum Alloy

    Science.gov (United States)

    Wang, Ping; Wu, Ting; Xiao, You Tao; Pu, Jun; Guo, Xiao Yang; Huang, Jun; Xiang, Chun Lang

    2016-09-01

    Al2O3 micro-powder was suspended in the basis electrolyte to form micro-arc oxidation (MAO) coatings on 6061 aluminum alloy by MAO. During the stage of micro-arc oxidation, Al2O3 micro-powder with negative surface charge was melted by the micro-arc around the anode and incorporated into the MAO coatings. With the continuous addition of Al2O3 micro-powder, the oxidation voltages rose up firstly and then decreased. The surface and cross-sectional morphologies showed that the size of micropores decreased and the MAO coatings surface got loosened following the variation in Al2O3 micro-powder concentration. As a consequence of the changing coating structure, the corrosion resistance of the coatings decreased apparently. The micro-hardness of the coatings increased firstly and then decreased, opposite to the trend of the average friction coefficient. It revealed the minimum average friction coefficient of MAO coatings and maximum adhesion between the coatings and substrate when 2.0 g/L Al2O3 micro-powder was added into electrolyte. There were visible cracks and peelings on the coating surface merely at 4.0 g/L after thermal shock tests. The x-ray diffraction results indicated that the addition of Al2O3 micro-powder had less effect on the phase composition of MAO coatings.

  6. Effects of pH, surface finish and thermal treatment on the corrosion of AlFeNi aluminum alloy. Characterization of oxide layers

    Science.gov (United States)

    Nabhan, D.; Kapusta, B.; Billaud, P.; Colas, K.; Hamon, D.; Dacheux, N.

    2015-02-01

    The aluminum alloy AlFeNi used as fuel cladding for the Jules Horowitz Reactor (JHR) may undergo corrosion in the reactor environment. In order to qualify the corrosion behavior of the fuel elements of the JHR in accidental conditions, several specimens of AlFeNi have been corroded at 250 °C for different durations (9-34 days) in distilled water at various pH (4.9, 5.2 and 5.6) chosen to simulate that currently considered for the JHR. On all specimens, the only crystalline corrosion product formed is boehmite (AlOOH). The corrosion film is composed of three oxide layers which show through thickness chemical composition variations. The iron-nickel precipitates pre-existing in the metal matrix are present in the inner and intermediate oxide layers though oxidized. For long corrosion times, some of the iron and nickel particles are released in the water and some precipitation is observed at the surface of the oxide layer. The effect of surface finish (as received or polished) and thermal treatment (annealed and not annealed) on the oxide growth rate has also been investigated. For durations over 25 days, pH = 5.6 appears to be more favorable than pH = 5.2 and 4.9 in terms of oxide thickness and weight gain limitation. This effect of pH is however reduced on unpolished specimens. The effect of surface finish on the corrosion behavior as measured by optical microscopy appears to be strong, especially for pH = 4.9 where polished samples exhibited an accelerated evolution of the oxide thickness and of the mass gain. This could be due to the combined effect of a strong acid solution (pH = 4.9) and of the local microstructural changes formed at the interface through polishing. The effect of thermal treatment on the behavior of unpolished AlFeNi specimens during corrosion tests in the conditions investigated was found to be small. In this study, microstructural and chemical analyses were performed on the corroded specimens in order to get a better understanding of the

  7. Effects of pH, surface finish and thermal treatment on the corrosion of AlFeNi aluminum alloy. Characterization of oxide layers

    Energy Technology Data Exchange (ETDEWEB)

    Nabhan, D., E-mail: diana.nabhan@cea.fr [Département des matériaux pour le nucléaire, CEA Saclay, 91191 Gif sur Yvette (France); Kapusta, B.; Billaud, P.; Colas, K.; Hamon, D. [Département des matériaux pour le nucléaire, CEA Saclay, 91191 Gif sur Yvette (France); Dacheux, N. [ICSM, UMR 5257 CNRS/CEA/UM2/ENSCM, Site de Marcoule, Bât 426, BP 17171, 30207 Bagnols/Cèze (France)

    2015-02-15

    The aluminum alloy AlFeNi used as fuel cladding for the Jules Horowitz Reactor (JHR) may undergo corrosion in the reactor environment. In order to qualify the corrosion behavior of the fuel elements of the JHR in accidental conditions, several specimens of AlFeNi have been corroded at 250 °C for different durations (9–34 days) in distilled water at various pH (4.9, 5.2 and 5.6) chosen to simulate that currently considered for the JHR. On all specimens, the only crystalline corrosion product formed is boehmite (AlOOH). The corrosion film is composed of three oxide layers which show through thickness chemical composition variations. The iron–nickel precipitates pre-existing in the metal matrix are present in the inner and intermediate oxide layers though oxidized. For long corrosion times, some of the iron and nickel particles are released in the water and some precipitation is observed at the surface of the oxide layer. The effect of surface finish (as received or polished) and thermal treatment (annealed and not annealed) on the oxide growth rate has also been investigated. For durations over 25 days, pH = 5.6 appears to be more favorable than pH = 5.2 and 4.9 in terms of oxide thickness and weight gain limitation. This effect of pH is however reduced on unpolished specimens. The effect of surface finish on the corrosion behavior as measured by optical microscopy appears to be strong, especially for pH = 4.9 where polished samples exhibited an accelerated evolution of the oxide thickness and of the mass gain. This could be due to the combined effect of a strong acid solution (pH = 4.9) and of the local microstructural changes formed at the interface through polishing. The effect of thermal treatment on the behavior of unpolished AlFeNi specimens during corrosion tests in the conditions investigated was found to be small. In this study, microstructural and chemical analyses were performed on the corroded specimens in order to get a better understanding of the

  8. Role of melt behavior in modifying oxidation distribution using an interface incorporated model in selective laser melting of aluminum-based material

    Science.gov (United States)

    Gu, Dongdong; Dai, Donghua

    2016-08-01

    A transient three dimensional model for describing the molten pool dynamics and the response of oxidation film evolution in the selective laser melting of aluminum-based material is proposed. The physical difference in both sides of the scan track, powder-solid transformation and temperature dependent physical properties are taken into account. It shows that the heat energy tends to accumulate in the powder material rather than in the as-fabricated part, leading to the formation of the asymmetrical patterns of the temperature contour and the attendant larger dimensions of the molten pool in the powder phase. As a higher volumetric energy density is applied (≥1300 J/mm3), a severe evaporation is produced with the upward direction of velocity vector in the irradiated powder region while a restricted operating temperature is obtained in the as-fabricated part. The velocity vector continuously changes from upward direction to the downward one as the scan speed increases from 100 mm/s to 300 mm/s, promoting the generation of the debris of the oxidation films and the resultant homogeneous distribution state in the matrix. For the applied hatch spacing of 50 μm, a restricted remelting phenomenon of the as-fabricated part is produced with the upward direction of the convection flow, significantly reducing the turbulence of the thermal-capillary convection on the breaking of the oxidation films, and therefore, the connected oxidation films through the neighboring layers are typically formed. The morphology and distribution of the oxidation are experimentally acquired, which are in a good agreement with the results predicted by simulation.

  9. Microstructural and mechanical properties of nanometric magnesium oxide particulate-reinforced aluminum matrix composites produced by powder metallurgy method

    International Nuclear Information System (INIS)

    In this research, aluminum alloy (A356.1) matrix composites reinforced with 1.5, 2.5 and 5 Vol.% nanoscale MgO particles were fabricated via powder metallurgy method. Pure atomized aluminum powder with an average particle size of 1μm and MgO particulate with an average particle size between 60 to 80 nm were used. The specimens were pressed by Cold Isostatic Press machine (CIP), and were subsequently sintered at various sintering temperatures, viz. 575, 600 and 625 .deg. C. Optimum amount of reinforcement and sintering temperature were determined by evaluating the density, microstructure and mechanical properties of composites. The composites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Hardness and compression tests were carried out in order to identify mechanical properties. Reinforcing the Al matrix alloy with MgO particles improved the hardness and compressive strength of the alloy to a maximum value of 44 BHN and 288 MPa, respectively. The most improved compressive strength was obtained with the specimen including 2.5% of MgO sintered at 625 .deg. C. According to the experiments, a sintering temperature of 625 .deg. C showed better results than other temperatures. A good distribution of the dispersed MgO particulates in the matrix alloy was achieved

  10. Preparation technology and anti-corrosion performances of black ceramic coatings formed by micro-arc oxidation on aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    CHEN Ling; HAN Jing; YU Shengxue

    2006-01-01

    In order to prepare ornamental and anti-corrosive coating on aluminum alloys, preparation technology of black micro-arc ceramic coatings on Al alloys in silicate based electrolyte was studied.The influence of content of Na2WO4 and combination additive in solution on the performance of black ceramic coatings was studied; the anticorrosion performances of black ceramic coatings were evaluated through whole-immersion test and electrochemical method in 3.5% NaCl solution at different pH value; SEM and XRD were used to analyze the surface morphology and phase constitutes of the black ceramic coatings.Experimental results indicated that, without combination additives, with the increasing of Na2WO4 content in the electrolyte, ceramic coating became darker and thicker, but the color was not black; after adding combination additive, the coating turned to be black; the black ceramic coating was multi-hole form in surface.There was a small quantity of tungsten existing in the black ceramic coating beside α-Al2O3 phase and β-Al2O3 phase.And aluminum alloy with black ceramic coating exhibited excellent anti-corrosion property in acid, basic and neutral 3.5% NaCl solution.

  11. Selective Template Wetting Routes to Hierarchical Polymer Films: Polymer Nanotubes from Phase-Separated Films via Solvent Annealing.

    Science.gov (United States)

    Ko, Hao-Wen; Cheng, Ming-Hsiang; Chi, Mu-Huan; Chang, Chun-Wei; Chen, Jiun-Tai

    2016-03-01

    We demonstrate a novel wetting method to prepare hierarchical polymer films with polymer nanotubes on selective regions. This strategy is based on the selective wetting abilities of polymer chains, annealed in different solvent vapors, into the nanopores of porous templates. Phase-separated films of polystyrene (PS) and poly(methyl methacrylate) (PMMA), two commonly used polymers, are prepared as a model system. After anodic aluminum oxide (AAO) templates are placed on the films, the samples are annealed in vapors of acetic acid, in which the PMMA chains are swollen and wet the nanopores of the AAO templates selectively. As a result, hierarchical polymer films containing PMMA nanotubes can be obtained after the AAO templates are removed. The distribution of the PMMA nanotubes of the hierarchical polymer films can also be controlled by changing the compositions of the polymer blends. This work not only presents a novel method to fabricate hierarchical polymer films with polymer nanotubes on selective regions, but also gives a deeper understanding in the selective wetting ability of polymer chains in solvent vapors. PMID:26831764

  12. 微波消解-火焰原子吸收光谱法测定氧化铝中的氧化钠%Determination of Sodium Oxide in Aluminum Oxide by Microwave Digestion-flame Atomic Absorption Spectrometry

    Institute of Scientific and Technical Information of China (English)

    薛心禄

    2012-01-01

    氧化铝中氧化钠含量的测定,一般采用高温熔结,用水浸出钠盐后,用原予吸收火焰光度法测定,该方法的测定周期比较长,而且高温熔结时对铂金皿的损耗比较大。文章提出了试样用磷酸和硫酸混合溶液,在高压微波消解器中进行处理,将样品在较短的时间内消解,并在试液中加入一定量的氯化铯,消除钠的电离干扰,采用原子吸收光谱法直接测定,测试结果与标准样品推荐值比较,结果令人满意。%The sodium oxide content in aluminum oxide is usually determined by atomic absorption spectrophotometry with high temperature melting and leaching, which is time consuming and damage platinum bowl. The paper proposed forward to determine with sample of mixed phosphoric acid and sulfuric acid solution to process in the high pressure microwave digestion device. The samples were digested in a relatively short time, and added a certain amount of cesium chloride in the test solution. Used for eliminate ionization interference of sodium to directly determine sodium oxide in aluminum oxide by Atomic Absorption Spectrophotometer. Under the comparison of test results and recommended values of standard samples, it was satisfactory.

  13. Sol-gel auto-combustion synthesis of hydroxyapatite nanotubes array in porous alumina template

    International Nuclear Information System (INIS)

    In this paper, an array of highly ordered hydroxyapatite (HAP) nanotubes was synthesized by sol-gel auto-combustion method with porous anodic aluminum oxide (AAO) template for the first time. Based on thermogravimetry (DTA/TG), Fourier transform infrared (FTIR) and X-ray diffraction (XRD), the dried gel, derived from the sol solution with Ca(NO3)2.4H2O and PO(CH3O)3 as precursors and ethylene glycol as the polymeric matrix, exhibited a typical self-propagating combustion behavior at low temperature, directly resulting in hexagonal crystalline HAP materials. The resultant HAP arrays fabricated from the above sol-gel in the AAO template were uniformly distributed, highly ordered nanotubes with uniform length and diameter according to the observations of scanning electron microscopy (SEM) and transmission electron microscope (TEM). The electron diffraction (ED), XRD and X-ray photoelectron spectroscopy (XPS) survey proved the formation of HAP phase with polycrystalline structure in the AAO template. Based on these results, a potential mechanism of 'an auto-combustion from dried gel to nanoparticles and a subsequent in situ reaction from nanoparticles to nanotubes' was proposed

  14. Fabrication of cobalt-nickel binary nanowires in a highly ordered alumina template via AC electrodeposition.

    Science.gov (United States)

    Ali, Ghafar; Maqbool, Muhammad

    2013-08-14

    Cobalt-nickel (Co-Ni) binary alloy nanowires of different compositions were co-deposited in the nanopores of highly ordered anodic aluminum oxide (AAO) templates from a single sulfate bath using alternating current (AC) electrodeposition. AC electrodeposition was accomplished without modifying or removing the barrier layer. Field emission scanning electron microscope was used to study the morphology of templates and alloy nanowires. Energy-dispersive X-ray analysis confirmed the deposition of Co-Ni alloy nanowires in the AAO templates. Average diameter of the alloy nanowires was approximately 40 nm which is equal to the diameter of nanopore. X-ray diffraction analysis showed that the alloy nanowires consisted of both hexagonal close-packed and face-centered cubic phases. Magnetic measurements showed that the easy x-axis of magnetization is parallel to the nanowires with coercivity of approximately 706 Oe. AC electrodeposition is very simple, fast, and is useful for the homogenous deposition of various secondary nanostuctured materials into the nanopores of AAO.

  15. Well-aligned carbon nanotube array membrane synthesized in porous alumina template by chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new simple approach was developed for preparing well-aligned and monodispersed carbon nanotube (CNT) array membrane within the cylindrical pores of anodic aluminum oxide (AAO) template by chemical vapor deposition (CVD). Acetylene and hydrogen were used in the CVD process with Fe-catalyzer at 700℃ under 250 Pa. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were employed to characterize the resulting highly- oriented uniform hollow tube array which had a diameter of about 250 nm, a tube density of 5.3′ 108 cm-2 and a length of about 60 m m. The length and diameter of the tubes depend on the thickness and pore diameter of the template. The growth properties of the CNT array film can be achieved by controlling the structure of the template, the particle size of Fe-catalyzer, the temperature in the reactor, the flow ratio and the deposition time. The highly-oriented and uniform CNT array membrane fabricated by this simple method is very much useful in a variety of applications.

  16. Fabrication of vertically aligned Pd nanowire array in AAO template by electrodeposition using neutral electrolyte

    Directory of Open Access Journals (Sweden)

    Yüzer Hayrettin

    2010-01-01

    Full Text Available Abstract A vertically aligned Pd nanowire array was successfully fabricated on an Au/Ti substrate using an anodic aluminum oxide (AAO template by a direct voltage electrodeposition method at room temperature using diluted neutral electrolyte. The fabrication of Pd nanowires was controlled by analyzing the current–time transient during electrodeposition using potentiostat. The AAO template and the Pd nanowires were characterized by scanning electron microscopy (SEM, energy-dispersive X-ray (EDX methods and X-Ray diffraction (XRD. It was observed that the Pd nanowire array was standing freely on an Au-coated Ti substrate after removing the AAO template in a relatively large area of about 5 cm2, approximately 50 nm in diameter and 2.5 μm in length with a high aspect ratio. The nucleation rate and the number of atoms in the critical nucleus were determined from the analysis of current transients. Pd nuclei density was calculated as 3.55 × 108 cm−2. Usage of diluted neutral electrolyte enables slower growing of Pd nanowires owing to increase in the electrodeposition potential and thus obtained Pd nanowires have higher crystallinity with lower dislocations. In fact, this high crystallinity of Pd nanowires provides them positive effect for sensor performances especially.

  17. Research on Preparation and Catalytic Performance of Zinc Oxide Powder Doped with Aluminum%掺铝氧化锌粉末的制备及其催化性能研究

    Institute of Scientific and Technical Information of China (English)

    许晨晨; 姚悦; 秦宗宏

    2015-01-01

    Zinc oxide powder doped with aluminum was prepared by the sol-gel method. Zinc oxide samples doped with different proportion aluminum were prepared through adding different amount of aluminum salt. XRD was used to test whether aluminum was doped in lattices of Zinc oxide powders. SEM was used to measure ap-pearances of zinc oxide powders doped with aluminum and reflects gatherings and distribution of particles. The laser particle analyser was used to measure sizes of particles. Zinc oxide samples degrade methyl red and bromo-cresol green by light. The best doped ratio of Zinc oxide was determined by observing degradation efficiencies of methyl red and bromocresol green. Result shows aluminum is doped in crystals. Degradation ratios of methyl red and bromocresol green are the highest efficiency ,when the mole ratio of mixed aluminum is 5%,calcination temperature is 500 ℃,and calcination time is 3 h.%采用溶胶凝胶法制备掺铝氧化锌粉末,通过控制铝盐的添加量来制备不同掺杂比例的掺铝氧化锌粉末,使用XRD来测试铝是否掺杂在氧化锌的晶格中,利用SEM来反映掺铝氧化锌粉末的外观以及颗粒分布聚集情况,用激光粒度分布仪来测其颗粒大小。并用所制备的氧化锌粉末样品对甲基红和溴甲酚绿进行光催化,使其降解,通过观察降解的效果,选择最佳的掺杂比例。结果表明,铝元素是掺杂在晶体中,且掺铝摩尔比为5%,煅烧温度为500℃,煅烧时间为3 h,其降解甲基红、溴甲酚绿效率最高。

  18. Aluminum Hydroxide

    Science.gov (United States)

    ... penicillamine (Cuprimine, Depen), prednisone (Deltasone, Orasone), products containing iron, tetracycline (Sumycin, Tetracap, and others), ticlopidine (Ticlid), and vitamins.be aware that aluminum hydroxide may interfere with other medicines, making them less ...

  19. Simulation, optimization and testing of a novel high spatial resolution X-ray imager based on Zinc Oxide nanowires in Anodic Aluminium Oxide membrane using Geant4

    International Nuclear Information System (INIS)

    In this work, a new generation of scintillator based X-ray imagers based on ZnO nanowires in Anodized Aluminum Oxide (AAO) nanoporous template is characterized. The optical response of ordered ZnO nanowire arrays in porous AAO template under low energy X-ray illumination is simulated by the Geant4 Monte Carlo code and compared with experimental results. The results show that for 10 keV X-ray photons, by considering the light guiding properties of zinc oxide inside the AAO template and suitable selection of detector thickness and pore diameter, the spatial resolution less than one micrometer and the detector detection efficiency of 66% are accessible. This novel nano scintillator detector can have many advantages for medical applications in the future

  20. Effects of electrical discharge surface modification of superalloy Haynes 230 with aluminum and molybdenum on oxidation behavior

    International Nuclear Information System (INIS)

    The effects of the electrical discharge alloying (EDA) process on improving the high temperature oxidation resistance of the Ni-based superalloy Haynes 230 have been investigated. The 85 at.% Al and 15 at.% Mo composite electrode provided the surface alloying materials. An Al-rich layer is produced on the surface of the EDA specimen alloyed with positive electrode polarity, whereas, many discontinuous piled layers are attached to the surface of the EDA superalloy when negative electrode polarity is selected. The oxidation resistance of the specimen alloyed with positive electrode polarity is better than that of the unalloyed superalloy, and the effective temperature of oxidation resistance of the alloyed layer can be achieved to 1100 oC. Conversely, the oxidation resistance of the other EDA specimen alloyed with negative electrode polarity is even worse than that of the unalloyed superalloy

  1. Predictive model for Pb(II) adsorption on soil minerals (oxides and low-crystalline aluminum silicate) consistent with spectroscopic evidence

    Science.gov (United States)

    Usiyama, Tomoki; Fukushi, Keisuke

    2016-10-01

    Mobility of Pb(II) in surface condition is governed by adsorption processes on soil minerals such as iron oxides and low-crystalline aluminum silicates. The adsorption effectiveness and the surface complex structures of Pb(II) vary sensitively with solution conditions such as pH, ionic strength, Pb(II) loading, and electrolyte anion type. This study was undertaken to construct a quantitative model for Pb(II) on soil minerals. It can predict the adsorption effectiveness and surface complex structures under any solution conditions using the extended triple layer model (ETLM). The Pb(II) adsorption data for goethite, hydrous ferric oxide (HFO), quartz, and low-crystalline aluminum silicate (LCAS) were analyzed with ETLM to retrieve the surface complexation reactions and these equilibrium constants. The adsorption data on goethite, HFO and quartz were referred from reports of earlier studies. Those data for LCAS were measured under a wide range of pH, ionic strength and Pb(II) loadings in NaNO3 and NaCl solutions. All adsorption data can be reasonably regressed using ETLM with the assumptions of inner sphere bidentate complexation and inner sphere monodentate ternary complexation with electrolyte anions, which are consistent with previously reported spectroscopic evidence. Predictions of surface speciation under widely various solution conditions using ETLM revealed that the inner sphere bidentate complex is the predominant species at neutral to high pH conditions. The inner sphere monodentate ternary complex becomes important at low pH, high surface Pb(II) coverage, and high electrolyte concentrations, of which the behavior is consistent with the spectroscopic observation. Comparisons of the obtained adsorption constants on goethite, HFO and quartz exhibited good linear relations between the reciprocals of dielectric constants of solids and adsorption constants. Those linear relations support predictions of the adsorption constants of all oxides based on Born

  2. Corrosion barriers for silver-based telescope mirrors: comparative study of plasma-enhanced atomic layer deposition and reactive evaporation of aluminum oxide

    Science.gov (United States)

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

    2015-10-01

    Astronomical telescopes continue to demand high-endurance high-reflectivity silver (Ag) mirrors that can withstand years of exposure in Earth-based observatory environments. We present promising results of improved Ag mirror robustness using plasma-enhanced atomic layer deposition (PEALD) of aluminum oxide (AlOx) as a top barrier layer. Transparent AlOx is suitable for many optical applications; therefore, it has been the initial material of choice for this study. Two coating recipes developed with electron beam ion-assisted deposition (e-beam IAD) of materials including yttrium fluoride, titanium nitride, oxides of yttrium, tantalum, and silicon are used to provide variations in basic Ag mirror structures to compare the endurance of reactive e-beam IAD barriers with PEALD barriers. Samples undergo high temperature/high humidity environmental testing in a controlled environment of 80% humidity at 80°C for 10 days. Environmental testing shows visible results suggesting that the PEALD AlOx barrier offers robust protection against chemical corrosion and moisture permeation. Ag mirror structures were further characterized by reflectivity/absorption before and after deposition of AlOx barriers.

  3. Influence of anodization parameters on the volume expansion of anodic aluminum oxide formed in mixed solution of phosphoric and oxalic acids

    Science.gov (United States)

    Kao, Tzung-Ta; Chang, Yao-Chung

    2014-01-01

    The growth of anodic alumina oxide was conducted in the mixed solution of phosphoric and oxalic acids. The influence of anodizing voltage, electrolyte temperature, and concentration of phosphoric and oxalic acids on the volume expansion of anodic aluminum oxide has been investigated. Either anodizing parameter is chosen to its full extent of range that allows the anodization process to be conducted without electric breakdown and to explore the highest possible volume expansion factor. The volume expansion factors were found to vary between 1.25 and 1.9 depending on the anodizing parameters. The variation is explained in connection with electric field, ion transport number, temperature effect, concentration, and activity of acids. The formation of anodic porous alumina at anodizing voltage 160 V in 1.1 M phosphoric acid mixed with 0.14 M oxalic acid at 2 °C showed the peak volume expansion factor of 1.9 and the corresponding moderate growth rate of 168 nm/min.

  4. Ultra-trace determination of arsenic species in environmental waters, food and biological samples using a modified aluminum oxide nanoparticle sorbent and AAS detection after multivariate optimization

    International Nuclear Information System (INIS)

    We describe a simple and efficient method for solid phase extraction and speciation of trace quantities of arsenic. It is based on the use of functionalized aluminum oxide nanoparticles and does not require any oxidation or reduction steps. The experimental parameters affecting extraction and quantitation were optimized using fractional factorial design methods. Adsorbed arsenic was eluted from the sorbent with 1 M hydrochloric acid and determined by graphite furnace atomic absorption spectrometry. Preconcentration factors up to 750 were achieved depending on the sample volume. Studies on potential interferences by various anions and cations showed the method to be highly selective. Under optimum conditions, the calibration plots are linear in the 5.0 to 280 ng L−1 and 8.0 to 260 ng L−1 concentration ranges for As(III) and total arsenic, respectively. The detection limits (calculated for S/N ratios of 3) are 1.81 and 1.97 ng L−1 for As(III) and total arsenic, respectively. The method was successfully applied to the determination and speciation of arsenic in (spiked) environmental, food and biological samples and gave good recoveries. The method was validated using a certified geological reference material. (author)

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

    Science.gov (United States)

    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.

  6. Effect of chronic accumulation of aluminum on renal function, cortical renal oxidative stress and cortical renal organic anion transport in rats.

    Science.gov (United States)

    Mahieu, Stella T; Gionotti, Marisa; Millen, Néstor; Elías, María Mónica

    2003-11-01

    The aim of the present work was to study the nephrotoxicity of aluminum lactate administered for 3 months (0.57 mg/100 g bodyweight aluminum, i.p., three times per week) to male Wistar rats. Renal function was studied after 6 weeks of treatment (urine was obtained from rats in metabolic cages) and at the end of the treatment using clearance techniques. Another group of rats was used as kidneys donors at the end of treatment. The renal cortex was separated and homogenized to determine glutathione (GSH) level, glutathione S-transferase (GST) activity and lipid peroxidation (LPO) level. Renal cortex slices were also used to study the p-aminohippuric acid (PAH) accumulation during steady-state conditions and the kinetics of uptake process. Clearance results, at the end of the treatment, indicated that renal functions in treated-rats were not different from those measured in control rats, although the renal concentration parameters differ when they were measured in treated rats after 24 h of food and water deprivation. Balances of water and sodium were also modified at both 1.5 and 3 months of treatment. The activity of alkaline phosphatase (AP) relative to inulin excreted in urine was significantly impaired: controls 2.2+/-0.6 IUI/mg, Al-treated 5.1+/-0.5 IU/mg, Prats. Renal accumulation of PAH, estimated as slice-to-medium ratio, decreased significantly in the Al-treated rats: control rats 3.06+/-0.02 ( n=12), Al-treated rats 2.26+/-0.04 ( n=12), Prats, while the apparent affinity remained unchanged. All these results indicate that aluminum accumulation in renal tissue affects cellular metabolism, promotes oxidative stress and induces alterations in renal tubular PAH transport, together with an impairment in sodium and water balance only detected under conditions of water deprivation, without other evident changes in glomerular filtration rate or other global functions measured by clearance techniques at least at this time of chronic toxicity.

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

    Directory of Open Access Journals (Sweden)

    Alberto eCastro-Muñiz

    2016-02-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  9. Decomposition kinetics of AgO cathode material for silver oxide/aluminum battery%铝氧化银电池正极材料AgO的分解动力学研究

    Institute of Scientific and Technical Information of China (English)

    吕霖娜; 林沛; 韩雪荣

    2011-01-01

    The instability of silver (Ⅱ). Oxide electrodes used in silver oxide/aluminum reserve batteries is the well-known cause of capacity loss and the delayed activation in reserve batteries after stored in the dry and inactivated state for the extended periods of time. The decomposition kinetics of the thermodynamically unstable AgO component of silver oxide cathodes used in silver/aluminum reverse batteries was determined by a rapid and accelerated-aging thermogravimetry (TG) technique. The calculated decomposition rates of AgO could be used to predict the storage life time of primary, and reserve silver oxide/aluminum reserve batteries.%氧化银的不稳定性是导致铝氧化银贮备电池在于态、未激活的状态下长期储存容量减少、激活时间延长的主要原因.通过加速老化实验测得电化学方法制备的氧化银的分解动力学参数,并通过建立模型计算氧化银的分解速率,以此来预测铝氧化银贮备电池中氧化银电极的储存寿命.

  10. Oxide-cladding aluminum nitride photonic crystal slab: Design and investigation of material dispersion and fabrication induced disorder

    Energy Technology Data Exchange (ETDEWEB)

    Melo, E. G., E-mail: emerdemelo@usp.br; Alvarado, M. A.; Carreño, M. N. P.; Alayo, M. I. [Electronic Systems Engineering Department, University of São Paulo, CEP 05508-010 São Paulo, SP (Brazil); Carvalho, D. O. [UNESP - São Paulo State University, CEP 13874-149 São João da Boa Vista, SP (Brazil); Ferlauto, A. S. [Department of Physics, Federal University of Minas Gerais, CEP 31270-901 Belo Horizonte, MG (Brazil)

    2016-01-14

    Photonic crystal slabs with a lower-index material surrounding the core layer are an attractive choice to circumvent the drawbacks in the fabrication of membranes suspended in air. In this work we propose a photonic crystal (PhC) slab structure composed of a triangular pattern of air holes in a multilayer thin film of aluminum nitride embedded in silicon dioxide layers designed for operating around 450 nm wavelengths. We show the design of an ideal structure and analyze the effects of material dispersion based on a first-order correction perturbation theory approach using dielectric functions obtained by experimental measurements of the thin film materials. Numerical methods were used to investigate the effects of fabrication induced disorder of typical nanofabrication processes on the bandgap size and spectral response of the proposed device. Deviation in holes radii and positions were introduced in the proposed PhC slab model with a Gaussian distribution profile. Impacts of slope in holes sidewalls that might result from the dry etching of AlN were also evaluated. The results show that for operation at the midgap frequency, slope in holes sidewalls is more critical than displacements in holes sizes and positions.

  11. Oxide-cladding aluminum nitride photonic crystal slab: Design and investigation of material dispersion and fabrication induced disorder

    International Nuclear Information System (INIS)

    Photonic crystal slabs with a lower-index material surrounding the core layer are an attractive choice to circumvent the drawbacks in the fabrication of membranes suspended in air. In this work we propose a photonic crystal (PhC) slab structure composed of a triangular pattern of air holes in a multilayer thin film of aluminum nitride embedded in silicon dioxide layers designed for operating around 450 nm wavelengths. We show the design of an ideal structure and analyze the effects of material dispersion based on a first-order correction perturbation theory approach using dielectric functions obtained by experimental measurements of the thin film materials. Numerical methods were used to investigate the effects of fabrication induced disorder of typical nanofabrication processes on the bandgap size and spectral response of the proposed device. Deviation in holes radii and positions were introduced in the proposed PhC slab model with a Gaussian distribution profile. Impacts of slope in holes sidewalls that might result from the dry etching of AlN were also evaluated. The results show that for operation at the midgap frequency, slope in holes sidewalls is more critical than displacements in holes sizes and positions

  12. Luminescence of the B{sup 2}{Sigma}{sup +}-X{sup 2}{Sigma}{sup +} band system of AlO during plasma electrolytic oxidation of aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Stojadinovic, S., E-mail: sstevan@ff.bg.ac.rs [Faculty of Physics, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia); Peric, M. [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia); Petkovic, M. [Faculty of Physics, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia); Vasilic, R. [Faculty of Environmental Governance and Corporate Responsibility, Educons University, Vojvode Putnika bb, Sremska Kamenica (Serbia); Kasalica, B.; Belca, I. [Faculty of Physics, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia); Radic-Peric, J. [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia)

    2011-11-30

    Highlights: > Plasma electrolytic oxidation (PEO) of aluminum in citric acid. > Luminescence of the B{sup 2}{Sigma}{sup +}-X{sup 2}{Sigma}{sup +} band system of AlO during PEO. > The measured intensity distributions are employed to estimate the mean plasma temperature. > The composition of plasma containing aluminum and oxygen is calculated. - Abstract: Two broad luminescence peaks with clearly pronounced structure, extending from roughly 18,200 to 18,800 cm{sup -1} and from 19,000 to 19,700 cm{sup -1} with the maxima at approximately 18,500 and 19,500 cm{sup -1}, respectively, are obtained during plasma electrolytic oxidation of aluminum. They are assigned to the v'-v'' = -1 and -2 band sequences of the B{sup 2}{Sigma}{sup +}-X{sup 2}{Sigma}{sup +} emission transition of AlO. The measured intensity distributions are employed to estimate the population of vibrational levels of the upper electronic state, and consequently the mean plasma temperature. The composition of plasma containing aluminum and oxygen under assumption of thermodynamic equilibrium is calculated in the temperature up to 11,000 K in order to explain the appearance of the observed spectral features.

  13. Synthesis and characterization of aluminum and Al/REE pillared clays and supported palladium catalysts for benzene oxidation

    Institute of Scientific and Technical Information of China (English)

    ZUO Shufeng; ZHOU Renxian; QI Chenze

    2011-01-01

    Volatile organic compounds (VOCs) are considered as a major pollutant in indoor and outdoor air. More stringent environmental regulations have been implemented in order to reduce the VOC emissions. One of the techniques available for destructive removal of VOCs is catalytic oxidation. In the present work, Al/Rare Earths (REE: Y, Ce, La, Pr and Nd) pillared clays (PILCs) were used to support 0.2 wt.% of palladium for the complete oxidation of low concentration of benzene. The supports and catalysts were characterized by XRD, N2 adsorption/desorption, FTIR spectroscopy, HRTEM and H2-TPR techniques. The results indicated that after Al and Al/REE pillaring, the basal spacing, SBET, Amic and Vmic of Al and AlREE-PILC had a considerable increase compared with those of Na-mmt. Activity tests of deep oxidation of benzene showed that the catalytic activity of Pd catalysts supported on Al and AlREE-PILC were much higher than that on initial clays,which was due to the fact that optimized structure of PILCs, such as large basal spacing, high SBET and porosity, improved Pd dispersion and increased the active sites of Pd. Especially for Pd/AlCe-PILC, the temperature of complete oxidation was about 280 C, exhibiting the highest catalytic activity.

  14. 铝合金阳极氧化无镍封孔工艺研究%The study of Aluminum alloy anodic oxidation and nickel hole sealing process

    Institute of Scientific and Technical Information of China (English)

    刘岩; 刘桂宏; 朱鸿昌; 张万龙; 高敏亮; 王亮; 王梅丰

    2015-01-01

    铝阳极氧化膜在不同封孔溶液中封闭后,其使用寿命和耐蚀性会各不相同。采用了磷铬酸失重法、电化学极化曲线法、交流阻抗法研究了铝合金阳极氧化膜在氟锆酸钾、HX-588封闭剂、钼酸钠、亚硝酸钠和纯水的高温水溶液封闭后的耐蚀性,比较其间的差异,并找出其变化规律,反映出五种溶液的封闭效果。数据表明:封闭效果优劣排序依次为HX-588封闭剂、氟锆酸钾、钼酸钠、亚硝酸钠、纯水。说明氟锆酸钾可以作为一种绿色无镍封孔剂进行工业生产。%The service life and corrosion resistance of sealed Aluminum anodic oxide film in different hole sealing solution will be different. The corrosion resistance of the sealed Aluminum oxide film in Zirconium fluoride acid potassium,HX-588 sealing agent,sodium molybdate,sodium nitrite and pure water of high temperature solution were studied by phosphorus-chromium acid weight-loss method and electrochemical polarization-curve method,electrochemical impedance spectros-copy,compare their differences and find out its change rule,reflects the sealing effect of 5 kinds of solution. The statistic shows that the sequence of sealing effect from excellent is HX-588 sealants,zirconium fluoride acid potassium,sodium mo-lybdate,sodium nitrite,pure water. That zirconium fluoride potassium can serve as a kind of green and nickel hole sealing a-gent for industrial production.

  15. Porous and mesh alumina formed by anodization of high purity aluminum films at low anodizing voltage

    Energy Technology Data Exchange (ETDEWEB)

    Abd-Elnaiem, Alaa M., E-mail: alaa.abd-elnaiem@science.au.edu.eg [KACST-Intel Consortium Center of Excellence in Nano-manufacturing Applications (CENA), Riyadh (Saudi Arabia); Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Mebed, A.M. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Department of Physics, Faculty of Science, Al-Jouf University, Sakaka 2014 (Saudi Arabia); El-Said, Waleed Ahmed [Department of Chemistry, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Abdel-Rahim, M.A. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt)

    2014-11-03

    Electrochemical oxidation of high-purity aluminum (Al) films under low anodizing voltages (1–10) V has been conducted to obtain anodic aluminum oxide (AAO) with ultra-small pore size and inter-pore distance. Different structures of AAO have been obtained e.g. nanoporous and mesh structures. Highly regular pore arrays with small pore size and inter-pore distance have been formed in oxalic or sulfuric acids at different temperatures (22–50 °C). It is found that the pore diameter, inter-pore distance and the barrier layer thickness are independent of the anodizing parameters, which is very different from the rules of general AAO fabrication. The brand formation mechanism has been revealed by the scanning electron microscope study. Regular nanopores are formed under 10 V at the beginning of the anodization and then serve as a template layer dominating the formation of ultra-small nanopores. Anodization that is performed at voltages less than 5 V leads to mesh structured alumina. In addition, we have introduced a simple one-pot synthesis method to develop thin walls of oxide containing lithium (Li) ions that could be used for battery application based on anodization of Al films in a supersaturated mixture of lithium phosphate and phosphoric acid as matrix for Li-composite electrolyte. - Highlights: • We develop anodic aluminum oxide (AAO) with small pore size and inter-pore distance. • Applying low anodizing voltages onto aluminum film leads to form mesh structures. • The value of anodizing voltage (1–10 V) has no effect on pore size or inter-pore distance. • Applying anodizing voltage less than 5 V leads to mesh structured AAO. • AAO can be used as a matrix for Li-composite electrolytes.

  16. Properties of alumina coating formed by microarc oxidation technique on 6061 aluminum alloy; Eigenschaften von mittels Microarc-Oxidations-Verfahren erzeugten Aluminiumbeschichtungen auf der Aluminiumlegierung 6061

    Energy Technology Data Exchange (ETDEWEB)

    Polat, Aytekin; Usta, Metin [Gebze Institute of Technology, Kocaeli (Turkey). Dept. of Materials Science and Engineering; Makaraci, Murat [Kocaeli Univ. (Turkey). Dept. of Mechanical Engineering; Tas, Zakir [Bozok Univ., Yozgat (Turkey); Ata, Ali

    2008-12-15

    In this study, thick and hard alumina coatings were produced on 6061-T6 Al alloy substrates for different oxidation times and current densities by using of microarc oxidation (MAO) technique in an alkali-silicate electrolytic solution. The influence of oxidation time and current density on the kinetics, phase composition, hardness, surface roughness and structure of the coating were investigated. It is found that the kinetics of coating mainly depends on applied current density and oxidation time. The XRD results revealed that the coatings are composed of mainly {alpha}-Al{sub 2}O{sub 3}, {gamma}-Al{sub 2}O{sub 3} and mullite phase. The relative ratio of harder and denser {alpha}-Al{sub 2}O{sub 3} phase increases with increasing current density and oxidation time. For the same coating time, the position of maximum hardness of coatings moves away from the substrate-coating interface to the coating surface with increasing current density. The surface roughness of coating is a function of coating thickness and increases with increasing deposition time and current density. The surface micro hardness of Al 6061-T6 alloy substrate was increased up to 2200 HV hardness after the coating. (orig.)

  17. Influence of composition and processing parameters on the properties of solution-processed aluminum phosphate oxide (AlPO) thin films

    Science.gov (United States)

    Norelli, Kevin M.; Plassmeyer, Paul N.; Woods, Keenan N.; Glassy, Benjamin A.; Knutson, Christopher C.; Beekman, Matt; Page, Catherine J.

    2016-05-01

    The effects of precursor solution concentration, composition, and spin-processing parameters on the thickness and electrical properties of ultra-smooth aluminum oxide phosphate (Al2O3-3x(PO4)2x or "AlPO") thin films prepared using aqueous solutions are reported. Compositions were verified by electron probe micro-analysis and range from Al2O1.5(PO4) to AlPO4 (x = P:Al from 0.5 to 1.0). Film thicknesses were determined using X-ray reflectivity measurements and were found to depend systematically on solution concentration, P:Al ratio, and spin-speed. Metal-insulator-semiconductor devices were fabricated to determine electrical properties as a function of composition. As the P:Al ratio increased from 0.5 to 1.0, the dielectric constant decreased from 6.0 to 4.6, leakage currents increased from 0.45 to 65 nA cm-2 at 1 MV cm-1 and dielectric breakdown (defined as leakage currents >10 μA cm-2) decreased from 9.74 to 2.84 MV cm-1. These results establish composition, concentration, and spin-speed for the production of AlPO films with targeted thicknesses and electrical properties.

  18. Optimization of aluminum-doped zinc oxide films deposited at low temperature by radio-frequency sputtering on flexible substrates for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, S. [Departamento de Energias Renovables, Energia Solar Fotovoltaica, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avda. Complutense 22, 28040 Madrid (Spain); Naranjo, F.B. [Grupo de Ingenieria Fotonica (GRIFO), Departamento de Electronica, Escuela Politecnica Superior, Universidad de Alcala, Campus Universitario, 28871 Alcala de Henares, Madrid (Spain)

    2010-02-15

    Aluminum-doped zinc oxide films were deposited at 100 C on polyethylene terephthalate by radio-frequency magnetron sputtering. The sputtering parameters such as RF power and Argon working pressure were varied from 25 to 125 W and from 1.1 to 0.2 Pa, respectively. The structural properties of as-deposited films were analysed by X-ray diffraction, showing that all the deposited films were polycrystalline, with hexagonal structure and a strong preferred c-axis orientation (0 0 2). Full width at half maximum and grain sizes were around 0.27 and ranged from 24 to 32 nm, respectively. The strain state of the samples was also estimated from X-ray diffraction measurements, obtaining compressive stresses from 0.29 to 0.05 GPa. Resistivity as low as 1.1 x 10{sup -3} {omega} cm was achieved for the film deposited at 75 W and 0.2 Pa, sample that showed a low strain state of -0.06 GPa. High optical transmittance ({proportional_to}80%) was exhibited when films were deposited at RF powers below 100 W. Band gap energies ranged from 3.36 to 3.39 eV and a refractive index of 1.80{+-}0.05, constant in the visible region, was also obtained. (author)

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

    Science.gov (United States)

    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. PMID:25942853

  20. 人工合成铁、铝矿对As(V)吸附的研究%Study on arsenate adsorption by synthetic iron and aluminum oxides/hydroxides

    Institute of Scientific and Technical Information of China (English)

    吴萍萍; 曾希柏

    2011-01-01

    Batch experiments were used to investigate arsenate adsorption by synthetic iron and aluminum oxides/hydroxides.The effects of adsorption time and pH on the adsorption behavior were also studied.The results showed that, As(V)adsorption by four iron and aluminum oxides/hydroxides increased with initial As(V) concentrations (0.1~100 mg/L), in which ferrihydrite showed a rising adsorption trend in the whole concentration range, with the adsorption amount of 22.56 mg/g at the initial As(V) of 100 mg/L.While the rapid increase in lower initial concentration and slow change in higher initial concentrations for the adsorption capacities of goethite, gibbsite, and hematite were obtained.When the initial As(V)reached 100mg/L, the least adsorption capacity of 4.75mg/g was received for hematite.Furthermore, the Freundlich equation fitted the data better than the Langmuir equation.The adsorption capacity of ferrihydrite is the highest, followed by goethite and gibbsite, and hematite shows lower adsorption capacity.With the increase of adsorption time, As(V) adsorption amount of four synthetic iron and aluminum oxides/hydroxides increased gradually, especially for ferrihydrite, reaching 96.3% of adsorption equilibrium in 10 minutes.The adsorption amount of goethite and gibbsite reached 97.4% and 97.2% of the equilibrium at 48h, respectively, while hematite required 96 hours to reach the equilibrium.Except ferrihydrite, four equations fitted the kinetic data better, especially the two-constant equation.The effect of pH on As(V) adsorption was associated to As(V) initial concentrations.In lower initial concentrations, adsorption of four synthetic iron and aluminum oxides/hydroxides decreased only under extremely alkaline conditions (pH>10), and when the initial concentrations were higher, adsorption amount dropped sharply with pH increasing.%采用批实验方法研究了人工合成铁、铝矿物对As(V)的吸附,考察吸附时间及溶液pH值对As(V)吸附的影

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

    Science.gov (United States)

    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.

  2. Effects of cathodic component of current on porosity and hardness characteristics of micro plasma oxidation(MPO) coatings on aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Samir Hamid Awad; QIAN Han-cheng

    2005-01-01

    Micro plasma oxidation(MPO) has recently been investigated as a novel,rapid and effective means to provide modified surfaces with improved properties of load bearing and wear resistance on light alloys particularly aluminum alloys.MPO is a multifactor-controlled process,these factors must be controlled to produce high quality coatings.The main research emphasis in MPO coating development over the past years seems to be the attainment of higher hardness levels and thick coatings.The porosity of MPO coating is the most complex phenomenon affecting the distribution,levels and the measurements of the hardness;and it is controlled by suitable selection of important parameters such as the electrical conditions.Ceramics coatings were synthesized on Al substrate by MPO to examine the effects of adding a cathodic phase alternated with anodic-cathodic current on the porosity and hardness characteristics of coatings by X-ray diffraction(XRD),scanning electron microscopy(SEM),and microhardness tester.The coatings produced by the combined mode are more dense and less porous than that by the anodic-cathodic mode.Microhardness test shows that the coatings produced by the combined mode exhibit both the highest hardness,and less reduction percentage in hardness with increasing the coatings thickness.These improvements become more significant for the polished and thicker coatings.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    María De La Luz Olvera

    2012-08-01

    Full Text Available 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.

  5. Aluminum-doped zinc oxide sol–gel thin films: Influence of the sol's water content on the resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Nehmann, Julia B., E-mail: nehmann@isfh.de [Institute for Solar Energy Research Hamelin (ISFH), Am Ohrberg 1, 31860 Emmerthal (Germany); Ehrmann, Nicole; Reineke-Koch, Rolf [Institute for Solar Energy Research Hamelin (ISFH), Am Ohrberg 1, 31860 Emmerthal (Germany); Bahnemann, Detlef W. [Institute for Technical Chemistry, Gottfried Wilhelm Leibniz University Hannover, Callinstrasse 3A, 30167 Hannover (Germany)

    2014-04-01

    Thin films of indium tin oxide (ITO) have gained substantial interest due to their optical and electrical properties. Since ITO is an expensive material and indium is a rare element, considerable attempts have been made to replace it by, e.g., aluminum-doped zinc oxide (ZnO:Al). The production of ZnO:Al is less cost-intensive, especially if the sol–gel technique is applied, while its properties are comparable to those of ITO. In this study, we demonstrate that the electrical properties of ZnO:Al thin films can be improved considerably by the addition of small amounts of ultrapure water to the dip coating solution during the preparation. The lowest resistivity obtained with a film prepared from a sol containing 0.2 M water is 2.8·10{sup −3Ω}cm. Optical modeling thus indicates an improvement of the free carrier mobility of films prepared from sols in the presence of additional water. The films prepared have an average thickness of 340 nm and a solar transmittance above 85% after annealing in a forming gas atmosphere. Clearly, the addition of water to the sol has a positive impact on the resistivity of the final ZnO:Al thin film. We suggest the observed increase of the free carrier mobility to be due to an improved electron transfer at the grain boundaries between the spherical nanoparticles. - Highlights: • We prepared ZnO:Al thin films with additional water in the sol by dip coating. • We found a positive impact of the water in the sol on the resistivity of the film. • The free carrier concentration and mobility increased with additional 0.2 M water. • The refractive indices demonstrate a denser structure related to the water content.

  6. Aluminum-doped zinc oxide sol–gel thin films: Influence of the sol's water content on the resistivity

    International Nuclear Information System (INIS)

    Thin films of indium tin oxide (ITO) have gained substantial interest due to their optical and electrical properties. Since ITO is an expensive material and indium is a rare element, considerable attempts have been made to replace it by, e.g., aluminum-doped zinc oxide (ZnO:Al). The production of ZnO:Al is less cost-intensive, especially if the sol–gel technique is applied, while its properties are comparable to those of ITO. In this study, we demonstrate that the electrical properties of ZnO:Al thin films can be improved considerably by the addition of small amounts of ultrapure water to the dip coating solution during the preparation. The lowest resistivity obtained with a film prepared from a sol containing 0.2 M water is 2.8·10−3Ωcm. Optical modeling thus indicates an improvement of the free carrier mobility of films prepared from sols in the presence of additional water. The films prepared have an average thickness of 340 nm and a solar transmittance above 85% after annealing in a forming gas atmosphere. Clearly, the addition of water to the sol has a positive impact on the resistivity of the final ZnO:Al thin film. We suggest the observed increase of the free carrier mobility to be due to an improved electron transfer at the grain boundaries between the spherical nanoparticles. - Highlights: • We prepared ZnO:Al thin films with additional water in the sol by dip coating. • We found a positive impact of the water in the sol on the resistivity of the film. • The free carrier concentration and mobility increased with additional 0.2 M water. • The refractive indices demonstrate a denser structure related to the water content

  7. images_template

    Data.gov (United States)

    National Aeronautics and Space Administration — Images for the website template go here. It will not change their names or locations, but will hopefully help to organize them. Oh, but for a directory structure...

  8. Templating mesoporous zeolites

    DEFF Research Database (Denmark)

    Egeblad, Kresten; Christensen, Christina Hviid; Kustova, Marina;

    2008-01-01

    The application of templating methods to produce zeolite materials with hierarchical bi- or trimodal pore size distributions is reviewed with emphasis on mesoporous materials. Hierarchical zeolite materials are categorized into three distinctly different types of materials: hierarchical zeolite c...

  9. Gas phase structures and charge localization in small aluminum oxide anions: Infrared photodissociation spectroscopy and electronic structure calculations

    Science.gov (United States)

    Song, Xiaowei; Fagiani, Matias R.; Gewinner, Sandy; Schöllkopf, Wieland; Asmis, Knut R.; Bischoff, Florian A.; Berger, Fabian; Sauer, Joachim

    2016-06-01

    We use cryogenic ion trap vibrational spectroscopy in combination with quantum chemical calculations to study the structure of mono- and dialuminum oxide anions. The infrared photodissociation spectra of D2-tagged AlO1-4- and Al2O3-6- are measured in the region from 400 to 1200 cm-1. Structures are assigned based on a comparison to simulated harmonic and anharmonic IR spectra derived from electronic structure calculations. The monoaluminum anions contain an even number of electrons and exhibit an electronic closed-shell ground state. The Al2O3-6- anions are oxygen-centered radicals. As a result of a delicate balance between localization and delocalization of the unpaired electron, only the BHLYP functional is able to qualitatively describe the observed IR spectra of all species with the exception of AlO3-. Terminal Al-O stretching modes are found between 1140 and 960 cm-1. Superoxo and peroxo stretching modes are found at higher (1120-1010 cm-1) and lower energies (850-570 cm-1), respectively. Four modes in-between 910 and 530 cm-1 represent the IR fingerprint of the common structural motif of dialuminum oxide anions, an asymmetric four-member Al-(O)2-Al ring.

  10. Virus templated metallic nanoparticles

    Science.gov (United States)

    Aljabali, Alaa A. A.; Barclay, J. Elaine; Lomonossoff, George P.; Evans, David J.

    2010-12-01

    Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron.Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron. Electronic supplementary information (ESI) available: Additional experimental detail, agarose gel electrophoresis results, energy dispersive X-ray spectra, ζ-potential measurements, dynamic light scattering data, nanoparticle tracking analysis and an atomic force microscopy image of Ni-CPMV. See DOI: 10.1039/c0nr00525h

  11. Ultrathin aluminum oxide films: Al-sublattice structure and the effect of substrate on ad-metal adhesion

    Energy Technology Data Exchange (ETDEWEB)

    JENNISON,DWIGHT R.; BOGICEVIC,ALEXANDER

    2000-03-06

    First principles density-functional slab calculations are used to study 5 {angstrom} (two O-layer) Al{sub 2}O{sub 3} films on Ru(0001) and Al(111). Using larger unit cells than in a recent study, it is found that the lowest energy stable film has an even mix of tetrahedral (t) and octahedral (o) site Al ions, and thus most closely resembles the {kappa}-phase of bulk alumina. Here, alternating zig-zag rows of t and o occur within the surface plane, resulting in a greater average lateral separation of the Al-ions than with pure t or o. A second structure with an even mix of t and o has also been found, consisting of alternating stripes. These patterns mix easily, can exist in three equivalent directions on basal substrates, and can also be displaced laterally, suggesting a mechanism for a loss of long-range order in the Al-sublattice. While the latter would cause the film to appear amorphous in diffraction experiments, local coordination and film density are little affected. On a film supported by rigid Ru(0001), overlayers of Cu, Pd, and Pt bind similarly as on bulk truncated {alpha}-Al{sub 2}O{sub 3}(0001). However, when the film is supported by soft Al(111), the adhesion of Cu, Pd, and Pt metal overlayers is significantly increased: Oxide-surface Al atoms rise so only they contact the overlayer, while substrate Al metal atoms migrate into the oxide film. Thus the binding energy of metal overlayers is strongly substrate dependent, and these numbers for the above Pd-overlayer systems bracket a recent experimentally derived value for a film on NiAl(110).

  12. TEM analysis and wear resistance of the ceramic coatings on Q235 steel prepared by hybrid method of hot-dipping aluminum and plasma electrolytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Lu Lihong [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Science and Research Department, Chinese People' s Armed Police Academy, Langfang 065000 (China); Zhang Jingwu [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Shen Dejiu, E-mail: sdj217@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Wu Lailei; Jiang Guirong [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Li Liang [State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084 (China)

    2012-01-25

    Highlights: Black-Right-Pointing-Pointer Transmission electron microscopy (TEM) was firstly used to analyze the phase composition of the ceramic coatings. Black-Right-Pointing-Pointer The phase composition of the ceramic coatings is mainly amorphous phase and crystal Al{sub 2}O{sub 3} oxides. Black-Right-Pointing-Pointer The cross-section micro-hardness of the treated samples was investigated, the hardness of the ceramic coatings is about HV1300. Black-Right-Pointing-Pointer The wear resistance of the PEO samples is about 3 times higher than that of the heat treated 45 steel. - Abstract: The hybrid method of PEO and hot-dipping aluminum (HDA) was employed to deposit composite ceramic coatings on the surface of Q235 steel. The composition of the composite coatings was investigated with X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The cross-section microstructure and micro-hardness of the treated specimens were investigated and analyzed with scanning electron microscopy (SEM) and microscopic hardness meter (MHM), respectively. The wear resistance of the ceramic coatings was investigated by a self-made rubbing wear testing machine. The results indicate that metallurgical bonding can be observed between the ceramic coatings and the steel substrate. There are many micro-pores and micro-cracks, which act as the discharge channels and result of quick and non-uniform cooling of melted sections in the plasma electrolytic oxidation ceramic coatings. The phase composition of the ceramic coatings is mainly composed of amorphous phase and crystal Al{sub 2}O{sub 3} oxides. The crystal Al{sub 2}O{sub 3} phase includes {kappa}-Al{sub 2}O{sub 3}, {theta}-Al{sub 2}O{sub 3} and {beta}-Al{sub 2}O{sub 3}. The grain size of the {kappa}-Al{sub 2}O{sub 3} crystal is quite non-uniform. The hardness of the ceramic coatings is about HV1300 and 10 times higher than that of the Q235 substrate, which was favorable to the better wear resistance of the ceramic

  13. Adhesive strength and structure of micro-arc oxidation ceramic coatings grown in-situ on LY12 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    WU Zhen-dong; JIANG Zhao-hua; YAO Zhong-ping

    2006-01-01

    The ceramic coatings containing zirconium dioxide were grown in-situ on LY12 aluminium alloy by micro-arc oxidation in mixed zirconate and phosphate solution. The phase composition and morphology of the coatings were studied by XRD and SEM.The adhesive strength of ceramic coatings was assessed by thermal shock test and tensile test. The results show that the coating is composed of m-ZrO2, t-ZrO2, and a little γ-Al2O3. Along the section of the coating, t-ZrO2 is more onboth sides than that in the middle, while m-ZrO2 is more in the middle than that on both sides. Meantime the coating is also composed of a dense layer and a loose layer. The coating has excellent thermal shock resistance under 550 ℃ and 600 ℃. And tensile tests show the adhesive strength of the dense layer of the coating with the substrate is more than 17.5 MPa.

  14. Aluminum-based metal-air batteries

    Energy Technology Data Exchange (ETDEWEB)

    Friesen, Cody A.; Martinez, Jose Antonio Bautista

    2016-01-12

    Provided in one embodiment is an electrochemical cell, comprising: (i) a plurality of electrodes, comprising a fuel electrode that comprises aluminum and an air electrode that absorbs gaseous oxygen, the electrodes being operable in a discharge mode wherein the aluminum is oxidized at the fuel electrode and oxygen is reduced at the air electrode, and (ii) an ionically conductive medium, comprising an organic solvent; wherein during non-use of the cell, the organic solvent promotes formation of a protective interface between the aluminum of the fuel electrode and the ionically conductive medium, and wherein at an onset of the discharge mode, at least some of the protective interface is removed from the aluminum to thereafter permit oxidation of the aluminum during the discharge mode.

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

    Science.gov (United States)

    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.

  16. The formation of tungsten doped Al2O3/ZnO coatings on aluminum by plasma electrolytic oxidation and their application in photocatalysis

    Science.gov (United States)

    Stojadinović, Stevan; Vasilić, Rastko; Radić, Nenad; Tadić, Nenad; Stefanov, Plamen; Grbić, Boško

    2016-07-01

    Tungsten doped Al2O3/ZnO coatings are formed by plasma electrolytic oxidation of aluminum substrate in supporting electrolyte (0.1 M boric acid + 0.05 M borax + 2 g/L ZnO) with addition of different concentrations of Na2WO4·2H2O. The morphology, crystal structure, chemical composition, and light absorption characteristics of formed surface coatings are investigated. The X-ray diffraction and X-ray photoelectron spectroscopy results indicate that formed surface coatings consist of alpha and gamma phase of Al2O3, ZnO, metallic tungsten and WO3. Obtained results showed that incorporated tungsten does not have any influence on the absorption spectra of Al2O3/ZnO coatings, which showed invariable band edge at about 385 nm. The photocatalytic activity of undoped and tungsten doped Al2O3/ZnO coatings is estimated by the photodegradation of methyl orange. The photocatalytic activity of tungsten doped Al2O3/ZnO coatings is higher thanof undoped Al2O3/ZnO coatings; the best photocatalytic activity is ascribed to coatings formed in supporting electrolyte with addition of 0.3 g/L Na2WO4·2H2O. Tungsten in Al2O3/ZnO coatings acts as a charge trap, thus reducing the recombination rate of photogenerated electron-hole pairs. The results of PL measurements are in agreement with photocatalytic activity. Declining PL intensity corresponds to increasing photocatalytic activity of the coatings, indicating slower recombination of electron-hole pairs.

  17. [Removal and Recycle of Phosphor from Water Using Magnetic Core/Shell Structured Fe₃O₄ @ SiO₂Nanoparticles Functionalized with Hydrous Aluminum Oxide].

    Science.gov (United States)

    Lai, Li; Xie, Qiang; Fang, Wen-kan; Xing, Ming-chao; Wu, De-yi

    2016-04-15

    A novel magnetic core/shell structured nano-particle Fe₃O₄@ SiO₂phosphor-removal ahsorbent functionalized with hydrous aluminum oxides (Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O) was synthesized. Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O was characterized by XRD, TEM, VSM and BET nitrogen adsorption experiment. The XRD and TEM results demonstrated the presence of the core/shell structure, with saturated magnetization and specific surface area of 56.00 emu · g⁻¹ and 47.27 m² · g⁻¹, respectively. In batch phosphor adsorption experiment, the Langmuir adsorption maximum capacity was 12.90 mg · g⁻¹ and nearly 96% phosphor could be rapidly removed within a contact time of 40 mm. Adsorption of phosphor on Fe₃O₄@ SiO₂@ Al₂O₃ · nH₂O was highly dependent on pH condition, and the favored pH range was 5-9 in which the phosphor removal rate was above 90%. In the treatment of sewage water, the recommended dosage was 1.25 kg · t⁻¹. In 5 cycles of adsorption-regeneration-desorption experiment, over 90% of the adsorbed phosphor could be desorbed with 1 mol · L⁻¹ NaOH, and Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O could be reused after regeneration by pH adjustment with slightly decreased phosphor removal rate with increasing recycling number, which proved the recyclability of Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O and thereby its potential in recycling of phosphor resources. PMID:27548967

  18. Aluminum doping tunes band gap energy level as well as oxidative stress-mediated cytotoxicity of ZnO nanoparticles in MCF-7 cells

    Science.gov (United States)

    Akhtar, Mohd Javed; Alhadlaq, Hisham A.; Alshamsan, Aws; Majeed Khan, M. A.; Ahamed, Maqusood

    2015-09-01

    We investigated whether Aluminum (Al) doping tunes band gap energy level as well as selective cytotoxicity of ZnO nanoparticles in human breast cancer cells (MCF-7). Pure and Al-doped ZnO nanoparticles were prepared by a simple sol-gel method. Characterization study confirmed the formation of single phase of AlxZn1-xO nanocrystals with the size range of 33-55 nm. Al-doping increased the band gap energy of ZnO nanoparticles (from 3.51 eV for pure to 3.87 eV for Al-doped ZnO). Al-doping also enhanced the cytotoxicity and oxidative stress response of ZnO nanoparticles in MCF-7 cells. The IC50 for undoped ZnO nanoparticles was 44 μg/ml while for the Al-doped ZnO counterparts was 31 μg/ml. Up-regulation of apoptotic genes (e.g. p53, bax/bcl2 ratio, caspase-3 & caspase-9) along with loss of mitochondrial membrane potential suggested that Al-doped ZnO nanoparticles induced apoptosis in MCF-7 cells through mitochondrial pathway. Importantly, Al-doping did not change the benign nature of ZnO nanoparticles towards normal cells suggesting that Al-doping improves the selective cytotoxicity of ZnO nanoparticles toward MCF-7 cells without affecting the normal cells. Our results indicated a novel approach through which the inherent selective cytotoxicity of ZnO nanoparticles against cancer cells can be further improved.

  19. Synthesis and characterization of biomorphic CeO2 obtained by using egg shell membrane as template

    OpenAIRE

    Marija Prekajski; Biljana Babić; Dušan Bučevac; Jelena Pantić; Jelena Gulicovski; Miroslav Miljković; Branko Matović

    2014-01-01

    A new technology based on bio-templating approach was proposed in this paper. Egg-shell membrane (ESM) has been employed as a natural biotemplate. Fibrous oxide ceramics was prepared by wet impregnation of biological template with water solution of cerium nitrate. The template was derived from membranes of fresh chicken eggs. Repeated impregnation, pyrolysis and final calcination in the range of 600 to 1200 °C in air resulted in template burnout and consolidation of the oxide layers. At lo...

  20. Double Emulsion Templated Celloidosomes

    Science.gov (United States)

    Arriaga, Laura R.; Marquez, Samantha M.; Kim, Shin-Hyun; Chang, Connie; Wilking, Jim; Monroy, Francisco; Marquez, Manuel; Weitz, David A.

    2012-02-01

    We present a novel approach for fabricating celloidosomes, which represent a hollow and spherical three-dimensional self-assembly of living cells encapsulating an aqueous core. Glass- capillary microfluidics is used to generate monodisperse water-in-oil-in-water double emulsion templates using lipids as stabilizers. Such templates allow for obtaining single but also double concentric celloidosomes. In addition, after a solvent removal step the double emulsion templates turn into monodisperse lipid vesicles, whose membrane spontaneously phase separates when choosing the adequate lipid composition, providing the adequate scaffold for fabricating Janus-celloidosomes. These structures may find applications in the development of bioreactors in which the synergistic effects of two different types of cells selectively adsorbed on one of the vesicle hemispheres may be exploited.

  1. Effect of Surface Oxidization on the Spectral Normal Emissivity of Aluminum 3A21 at the Wavelength of 1.5 m Over the Temperature Range from 800 K to 910 K

    Science.gov (United States)

    Shi, Deheng; Zou, Fenghui; Wang, Shuai; Zhu, Zunlue; Sun, Jinfeng

    2015-04-01

    This study explores the dependence of the spectral emissivity on the temperature ranging from 800 K to 910 K for an oxidizing surface of aluminum 3A21. In this experiment, the infrared radiation stemming from the specimen is received by an InGaAs photodiode detector, which operates at the wavelength of 1.5 m with a bandwidth of about 20 nm. The temperature of the specimen surface is determined by averaging the two R-type platinum-rhodium thermocouples, which are tightly welded on the specimen surface. The spectral emissivity is reported before the first measurement over the temperature range from 800 K to 910 K. The variation of the spectral emissivity with the heating time is evaluated at a given temperature. The variation of the spectral emissivity with temperature is discussed for a given heating time. Oscillations of the spectral emissivity have been observed, which are affirmed to be connected with the thickness of the oxidization layer on the specimen surface, and formed by the interference effect between the radiation coming from the oxidization layer and the radiation stemming from the substrate. The effect of surface oxidization on the spectral emissivity of aluminum 3A21 is evaluated, and compared with that of SPHC steel. Analytical expressions of the spectral emissivity of aluminum 3A21 versus the temperature are derived at some given heating times. A conclusion is obtained that the experimental results obtained at a given heating time from 800 K to 910 K abide by the same functional form.

  2. Joomla! 3 template essentials

    CERN Document Server

    Frankowski, Pawel

    2013-01-01

    Using this hands-on, step-by step tutorial filled with practical examples, the readers will be able to create beautiful templates and themes for your websites that will make them stand out from others.This book is written for all of you who wish to create your own unique templates for Joomla! 3.x. This book can be used by Joomla! administrators or visual designers (with no programming experience) or those of you who are used to working with common web developer tools like HTML/CSS editors for coding purposes. You would need basic knowledge of Joomla! and some knowledge of CSS and HTML.

  3. Computing layouts with deformable templates

    KAUST Repository

    Peng, Chihan

    2014-07-27

    In this paper, we tackle the problem of tiling a domain with a set of deformable templates. A valid solution to this problem completely covers the domain with templates such that the templates do not overlap. We generalize existing specialized solutions and formulate a general layout problem by modeling important constraints and admissible template deformations. Our main idea is to break the layout algorithm into two steps: a discrete step to lay out the approximate template positions and a continuous step to refine the template shapes. Our approach is suitable for a large class of applications, including floorplans, urban layouts, and arts and design. Copyright © ACM.

  4. The formation of an ordered microporous aluminum-based material mediated by phthalic acid.

    Science.gov (United States)

    Zhang, Wei; Cai, Jian-Hua; Huang, Pei-Pei; Hu, Lin-Lin; Cao, An-Min; Wan, Li-Jun

    2016-06-28

    By using phthalic acid as a soft template, we showed that it was possible to prepare a microporous aluminum-based material when the precipitation of Al(3+) was properly controlled. We also identified that this microporous aluminum-based material could be promising for the removal of fluoride ions in water treatment. PMID:27263661

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

    Science.gov (United States)

    Bakas, Michael P [Ammon, ID; Lillo, Thomas M [Idaho Falls, ID; Chu, Henry S [Idaho Falls, ID

    2010-11-16

    Methods of forming aluminum oxynitride (AlON) materials include sintering green bodies comprising aluminum orthophosphate or another sacrificial material therein. Such green bodies may comprise aluminum, oxygen, and nitrogen in addition to the aluminum orthophosphate. For example, the green bodies may include a mixture of aluminum oxide, aluminum nitride, and aluminum orthophosphate or another sacrificial material. Additional methods of forming aluminum oxynitride (AlON) materials include sintering a green body including a sacrificial material therein, using the sacrificial material to form pores in the green body during sintering, and infiltrating the pores formed in the green body with a liquid infiltrant during sintering. Bodies are formed using such methods.

  6. Aluminum oxide as a dual-functional modifier of Ni-based anodes of solid oxide fuel cells for operation on simulated biogas

    Science.gov (United States)

    Wang, Feng; Wang, Wei; Ran, Ran; Tade, Moses O.; Shao, Zongping

    2014-12-01

    Al2O3 and SnO2 additives are introduced into the Ni-YSZ cermet anode of solid oxide fuel cells (SOFCs) for operation on simulated biogas. The effects of incorporating Al2O3/SnO2 on the electrical conductivity, morphology, coking resistance and catalytic activity for biogas reforming of the cermet anode are systematically studied. The electrochemical performance of the internal reforming SOFC is enhanced by introducing an appropriate amount of Al2O3 into the anode, but it becomes worse with excess alumina addition. For SnO2, a negative effect on the electrochemical performance is demonstrated, although the coking resistance of the anode is improved. For fuel cells operating on biogas, stable operation under a polarization current for 130 h at 750 °C is achieved for a cell with an Al2O3-modified anode, while cells with unmodified or SnO2-modified Ni-YSZ anodes show much poorer stability under the same conditions. The improved performance of the cell with the Al2O3-modified anode mainly results from the suppressed coking and sintering of the anode and from the formation of NiAl2O4 in the unreduced anode. In sum, modifying the anode with Al2O3 may be a useful and facile way to improve the coking resistance and electrochemical performance of the nickel-based cermet anodes for SOFCs.

  7. Metal-ceramic adhesion: Synthesis of aluminum and chromium mixed metal oxides and extended Hueckel modeling of metal-metal oxide interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Boorse, R.S.

    1993-01-01

    Methods of chemical synthesis and theoretical calculation was used to form new materials that have improved adhesion of a thin metal film to a ceramic. Two goals of this investigation were to develop new synthesis of metal-ceramic couples with improved adhesion between the two components and a fundamental understanding of the chemical factors that affect adhesion. Extended Hueckel calculations were performed on a series of Pt- and NiPt-NiO metal-ceramic couples to examine bonding. The calculations showed an 5 fold increase in adhesion energy in NiPt-NiO over Pt-NiO. Bonding across the interface is found to decrease with increased electron donation as interfacially antibonding orbitals are filled. The synthesis of (Al[sub 1[minus]x]Cr[sub x])[sub 2]O[sub 3] mixed metal oxide powders and coatings by sol-gel methodology utilizing three chromium precursors is reported. Thus, Al[Cr(CO)[sub 3]C[sub 5]H[sub 5

  8. The Technological Improvements of Aluminum Alloy Coloring by Electrolysis

    Institute of Scientific and Technical Information of China (English)

    LI Nai-jun

    2004-01-01

    The technological process of coloring golden-tawny on aluminum alloy by electrolysis was improved in this paper. The optimum composition of electrolyte was found, the conditions of deposition and anodic oxidation by electrolysis were studied. The oxidative membrane on aluminum alloy was satisfying, the colored aluminum alloy by electrolysis is uniformity,bright and beautiful, and the coloring by electrolysis is convenient and no pollution.

  9. Template Composite Dark Matter

    DEFF Research Database (Denmark)

    Drach, Vincent; Hietanen, Ari; Pica, Claudio;

    2015-01-01

    We present a non perturbative study of SU(2) gauge theory with two fundamental Dirac flavours. We discuss how the model can be used as a template for composite Dark Matter (DM). We estimate one particular interaction of the DM candidate with the Standard Model : the interaction through photon...

  10. Biometric template revocation

    Science.gov (United States)

    Arndt, Craig M.

    2004-08-01

    Biometric are a powerful technology for identifying humans both locally and at a distance. In order to perform identification or verification biometric systems capture an image of some biometric of a user or subject. The image is then converted mathematical to representation of the person call a template. Since we know that every human in the world is different each human will have different biometric images (different fingerprints, or faces, etc.). This is what makes biometrics useful for identification. However unlike a credit card number or a password to can be given to a person and later revoked if it is compromised and biometric is with the person for life. The problem then is to develop biometric templates witch can be easily revoked and reissued which are also unique to the user and can be easily used for identification and verification. In this paper we develop and present a method to generate a set of templates which are fully unique to the individual and also revocable. By using bases set compression algorithms in an n-dimensional orthogonal space we can represent a give biometric image in an infinite number of equally valued and unique ways. The verification and biometric matching system would be presented with a given template and revocation code. The code will then representing where in the sequence of n-dimensional vectors to start the recognition.

  11. Effects of size and surface of zinc oxide and aluminum-doped zinc oxide nanoparticles on cell viability inferred by proteomic analyses

    Directory of Open Access Journals (Sweden)

    Pan CH

    2014-08-01

    Full Text Available Chih-Hong Pan,1,2,* Wen-Te Liu,3,4,* Mauo-Ying Bien,4,5 I-Chan Lin,6 Ta-Chih Hsiao,7 Chih-Ming Ma,8 Ching-Huang Lai,2 Mei-Chieh Chen,9 Kai-Jen Chuang,10,11 Hsiao-Chi Chuang3,4 On behalf of the Taiwan CardioPulmonary Research (T-CPR Group 1Institute of Labor, Occupational Safety and Health, Ministry of Labor, 2School of Public Health, National Defense Medical Center, 3Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, 4School of Respiratory Therapy, College of Medicine, 5Division of Pulmonary Medicine, Department of Internal Medicine, Taipei Medical University Hospital, 6Department of Ophthalmology, Shuang Ho Hospital, Taipei Medical University, Taipei, 7Graduate Institute of Environmental Engineering, National Central University, Taoyuan, 8Department of Cosmetic Application and Management, St Mary’s Junior College of Medicine, Nursing and Management, Sanxing, 9Department of Microbiology and Immunology, College of Medicine, 10Department of Public Health, School of Medicine, College of Medicine, 11School of Public Health, College of Public Health and Nutrition, Taipei Medical University, Taipei, Taiwan *These authors contributed equally to this work Abstract: Although the health effects of zinc oxide nanoparticles (ZnONPs on the ­respiratory system have been reported, the fate, potential toxicity, and mechanisms in biological cells of these particles, as related to particle size and surface characteristics, have not been well elucidated. To determine the physicochemical properties of ZnONPs that govern cytotoxicity, we investigated the effects of size, electronic properties, zinc concentration, and pH on cell viability using human alveolar-basal epithelial A549 cells as a model. We observed that a 2-hour or longer exposure to ZnONPs induced changes in cell viability. The alteration in cell viability was associated with the zeta potentials and pH values of the ZnONPs. Proteomic profiling of A549 exposed to Zn

  12. Magnetic characteristics of CoPd and FePd antidot arrays on nanoperforated Al2O3 templates

    Science.gov (United States)

    Maximenko, A.; Fedotova, J.; Marszałek, M.; Zarzycki, A.; Zabila, Y.

    2016-02-01

    Hard magnetic antidot arrays show promising results in context of designing of percolated perpendicular media. In this work the technology of magnetic FePd and CoPd antidot arrays fabrication is presented and correlation between surface morphology, structure and magnetic properties is discussed. CoPd and FePd antidot arrays were fabricated by deposition of Co/Pd and Fe/Pd multilayers (MLs) on porous anodic aluminum oxide templates with bowl-shape cell structure with inclined intercellular regions. FePd ordered L10 structure was obtained by successive vacuum annealing at elevated temperatures (530 °C) and confirmed by XRD analysis. Systematic analysis of magnetization curves evidenced perpendicular magnetic anisotropy of CoPd antidot arrays, while FePd antidot arrays revealed isotropic magnetic anisotropy with increased out-of-plane magnetic contribution. MFM images of antidots showed more complicated contrast, with alternating magnetic dots oriented parallel and antiparallel to tip magnetization moment.

  13. Effect of Na2WO4 on Growth Process and Corrosion Resistance of Micro-arc Oxidation Coatings on 2A12 Aluminum Alloys in CH3COONa Electrolyte

    Science.gov (United States)

    Lin, Zhaoqing; Yu, Huijun; He, Siyu; Wang, Diangang; Chen, Chuanzhong

    2016-01-01

    Ceramic coatings were deposited on 2A12 aluminum alloys using micro-arc oxidation (MAO) technology in CH3COONa-Na2WO4 electrolyte. The MAO process was studied by recording the current-time curve. The influences of Na2WO4 concentrations on the coatings in CH3COONa electrolyte were investigated. The results show that the Na2WO4 concentrations affect the MAO process and performances of the coatings directly. Na2WO4 in excess is harmful for the formation of Al2O3 in this electrolyte. The corrosion resistance was enhanced with the decrease of Na2WO4 concentration.

  14. Gating of Permanent Molds for ALuminum Casting

    Energy Technology Data Exchange (ETDEWEB)

    David Schwam; John F. Wallace; Tom Engle; Qingming Chang

    2004-03-30

    This report summarizes a two-year project, DE-FC07-01ID13983 that concerns the gating of aluminum castings in permanent molds. The main goal of the project is to improve the quality of aluminum castings produced in permanent molds. The approach taken was determine how the vertical type gating systems used for permanent mold castings can be designed to fill the mold cavity with a minimum of damage to the quality of the resulting casting. It is evident that somewhat different systems are preferred for different shapes and sizes of aluminum castings. The main problems caused by improper gating are entrained aluminum oxide films and entrapped gas. The project highlights the characteristic features of gating systems used in permanent mold aluminum foundries and recommends gating procedures designed to avoid common defects. The study also provides direct evidence on the filling pattern and heat flow behavior in permanent mold castings.

  15. In search of templates

    OpenAIRE

    Gobet, F.; Jackson, S

    2001-01-01

    This paper explores, both wit This study reflects a recent shift towards the study of early stages of expert memory acquisition for chess positions. Over the course of fifteen sessions, two subjects who knew virtually nothing about the game of chess were trained to memorise positions. Increase in recall performance and chunk size was captured by power functions, confirming predictions made by the template theory (Gobet & Simon, 1996, 1998, 2000). The human data was compared to that of a compu...

  16. Al/sub 2/S/sub 3/ preparation and use in electrolysis process for aluminum production

    Science.gov (United States)

    Hsu, C.C.; Loutfy, R.O.; Yao, N.P.

    A continuous process for producing aluminum sulfide and for electrolyzing the aluminum sulfide to form metallic aluminum in which the aluminum sulfide is produced from aluminum oxide and COS or CS/sub 2/ in the presence of a chloride melt which also serves as the electrolysis bath. Circulation between the reactor and electrolysis cell is carried out to maintain the desired concentration of aluminum sulfide in the bath.

  17. Absorptive coating for aluminum solar panels

    Science.gov (United States)

    Desmet, D.; Jason, A.; Parr, A.

    1979-01-01

    Method for coating forming coating of copper oxide from copper component of sheet aluminum/copper alloy provides strong durable solar heat collector panels. Copper oxide coating has solar absorption characteristics similar to black chrome and is much simpler and less costly to produce.

  18. MOF作模板制备多孔Au/CuxO催化剂及其CO氧化性能%MOF-templated preparation of porous Au/CuxO catalysts with octahedral structures for CO oxidation

    Institute of Scientific and Technical Information of China (English)

    刘朋飞; 张所瀛; 杨祝红; 陆小华

    2016-01-01

    采用MOF材料作模板,通过在Cu-BTC材料表面预先负载贵金属Au再热解的方法,成功制备了具有正八面体结构的新型多孔Au/CuxO负载型催化剂。通过降低热解环境中的O2浓度,调节氧化时间,实现了Au/Cu-BTC氧化产物组分的调节,分别制得了Au/Cu2O、Au/Cu2O-CuO、Au/CuO复合催化材料。将其用于CO催化氧化,发现所有Au/CuxO催化剂都表现出比Cu-BTC和Au/Cu-BTC更优异的催化性能,其中由于拥有较高的比表面积、Cu2O含量以及更好的Au的分散性,Au/Cu2O的CO氧化活性最佳,180℃即能实现CO的完全转化。%More recently, metal-organic frameworks (MOFs), as a excellent sacrificial template, have been widely used to fabricate a variety of porous metal oxides with special structures and performances. To take full advantage of MOFs in composition regulation, herein a novel method to prepare porous Au/CuxO composites with octahedral structures inherited from MOFs was introduced. Au/Cu-BTC was firstly prepared by the traditional deposition-precipitation method. Subsequently, pyrolysis of Au/Cu-BTC was conducted in 2% (volume fraction) O2 balanced with helium. By varying the time of heating, Au/CuxO composites including Au/Cu2O, Au/Cu2O-CuO and Au/CuO were successfully achieved. When tested in CO oxidation, these supported catalysts exhibited much better catalytic performances than Cu-BTC and Au/Cu-BTC due to the more active support of metal oxides. Thus, Au/Cu2O showed the best catalytic activity since the high surface area, Cu2O content and better dispersion of Au.

  19. NLG vs. Templates

    OpenAIRE

    Reiter, Ehud

    1995-01-01

    One of the most important questions in applied NLG is what benefits (or `value-added', in business-speak) NLG technology offers over template-based approaches. Despite the importance of this question to the applied NLG community, however, it has not been discussed much in the research NLG community, which I think is a pity. In this paper, I try to summarize the issues involved and recap current thinking on this topic. My goal is not to answer this question (I don't think we know enough to be ...

  20. Enhanced lithium ion battery cycling of silicon nanowire anodes by template growth to eliminate silicon underlayer islands.

    Science.gov (United States)

    Cho, Jeong-Hyun; Picraux, S Tom

    2013-01-01

    It is well-known that one-dimensional nanostructures reduce pulverization of silicon (Si)-based anode materials during Li ion cycling because they allow lateral relaxation. However, even with improved designs, Si nanowire-based structures still exhibit limited cycling stability for extended numbers of cycles, with the specific capacity retention with cycling not showing significant improvements over commercial carbon-based anode materials. We have found that one important reason for the lack of long cycling stability can be the presence of milli- and microscale Si islands which typically form under nanowire arrays during their growth. Stress buildup in these Si island underlayers with cycling results in cracking, and the loss of specific capacity for Si nanowire anodes, due to progressive loss of contact with current collectors. We show that the formation of these parasitic Si islands for Si nanowires grown directly on metal current collectors can be avoided by growth through anodized aluminum oxide templates containing a high density of sub-100 nm nanopores. Using this template approach we demonstrate significantly enhanced cycling stability for Si nanowire-based lithium-ion battery anodes, with retentions of more than ~1000 mA·h/g discharge capacity over 1100 cycles.

  1. Enhanced lithium ion battery cycling of silicon nanowire anodes by template growth to eliminate silicon underlayer islands.

    Science.gov (United States)

    Cho, Jeong-Hyun; Picraux, S Tom

    2013-01-01

    It is well-known that one-dimensional nanostructures reduce pulverization of silicon (Si)-based anode materials during Li ion cycling because they allow lateral relaxation. However, even with improved designs, Si nanowire-based structures still exhibit limited cycling stability for extended numbers of cycles, with the specific capacity retention with cycling not showing significant improvements over commercial carbon-based anode materials. We have found that one important reason for the lack of long cycling stability can be the presence of milli- and microscale Si islands which typically form under nanowire arrays during their growth. Stress buildup in these Si island underlayers with cycling results in cracking, and the loss of specific capacity for Si nanowire anodes, due to progressive loss of contact with current collectors. We show that the formation of these parasitic Si islands for Si nanowires grown directly on metal current collectors can be avoided by growth through anodized aluminum oxide templates containing a high density of sub-100 nm nanopores. Using this template approach we demonstrate significantly enhanced cycling stability for Si nanowire-based lithium-ion battery anodes, with retentions of more than ~1000 mA·h/g discharge capacity over 1100 cycles. PMID:24144166

  2. ALUMINUM BOX BUNDLING PRESS

    Directory of Open Access Journals (Sweden)

    Iosif DUMITRESCU

    2015-05-01

    Full Text Available In municipal solid waste, aluminum is the main nonferrous metal, approximately 80- 85% of the total nonferrous metals. The income per ton gained from aluminum recuperation is 20 times higher than from glass, steel boxes or paper recuperation. The object of this paper is the design of a 300 kN press for aluminum box bundling.

  3. Aluminum-rich mesoporous MFI - type zeolite single crystals

    DEFF Research Database (Denmark)

    Kustova, Marina; Kustov, Arkadii; Christensen, Christina Hviid

    2005-01-01

    Zeolitcs are crystalline materials, which are widely used as solid acid catalysts and supports in many industrial processes. Recently, mesoporous MFI-type zeolite single crystals were synthesized by use of carbon particles as a mesopore template and sodium aluminate as the aluminum Source....... With this technique, only zeolites with relatively low Al contents were reported (Si/Al ratio about 100). In this work, the preparation of aluminum-rich mesoporous MFI-type zeolite single crystals (Si/Al similar to 16-50) using aluminum isopropoxide as the aluminum Source is reported for the first time. All samples...... are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), ammonia temperature programmed desorption (NH3-TPD), and N-2 adsorption measurements. The obtained zeolites combine the high crystallinity and the characteristic micropores of zeolites with an intracrystalline mesopore system...

  4. A liquid aluminum corrosion resistance surface on steel substrate

    International Nuclear Information System (INIS)

    The process of hot dipping pure aluminum on a steel substrate followed by oxidation was studied to form a surface layer of aluminum oxide resistant to the corrosion of aluminum melt. The thickness of the pure aluminum layer on the steel substrate is reduced with the increase in temperature and time in initial aluminizing, and the thickness of the aluminum layer does not increase with time at given temperature when identical temperature and complete wetting occur between liquid aluminum and the substrate surface. The thickness of the Fe-Al intermetallic layer on the steel base is increased with increasing bath temperature and time. Based on the experimental data and the mathematics model developed by the study, a maximum exists in the thickness of the Fe-Al intermetallic at certain dipping temperature. X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis reveals that the top portion of the steel substrate is composed of a thin layer of α-Al2O3, followed by a thinner layer of FeAl3, and then a much thicker one of Fe2Al5 on the steel base side. In addition, there is a carbon enrichment zone in diffusion front. The aluminum oxide surface formed on the steel substrate is in perfect condition after corrosion test in liquid aluminum at 750 deg. C for 240 h, showing extremely good resistance to aluminum melt corrosion

  5. Template-synthesized opal hydrogels

    Institute of Scientific and Technical Information of China (English)

    LI Jun; JI Lijun; RONG Jianhua; YANG Zhenzhong

    2003-01-01

    Opal hydrogels could be synthesized with polymer inverse opal template. A pH responsive opal N-iso- propylacrylamide/acrylic acid copolymerized hydrogel was prepared as an example. The ordered structure and response to pH were investigated. Through the sol-gel process of tetrabutyl titanate, opal titania was obtained with the opal hydrogel template.

  6. Sacrificial template method of fabricating a nanotube

    Science.gov (United States)

    Yang, Peidong; He, Rongrui; Goldberger, Joshua; Fan, Rong; Wu, Yi-Ying; Li, Deyu; Majumdar, Arun

    2007-05-01

    Methods of fabricating uniform nanotubes are described in which nanotubes were synthesized as sheaths over nanowire templates, such as using a chemical vapor deposition process. For example, single-crystalline zinc oxide (ZnO) nanowires are utilized as templates over which gallium nitride (GaN) is epitaxially grown. The ZnO templates are then removed, such as by thermal reduction and evaporation. The completed single-crystalline GaN nanotubes preferably have inner diameters ranging from 30 nm to 200 nm, and wall thicknesses between 5 and 50 nm. Transmission electron microscopy studies show that the resultant nanotubes are single-crystalline with a wurtzite structure, and are oriented along the direction. The present invention exemplifies single-crystalline nanotubes of materials with a non-layered crystal structure. Similar "epitaxial-casting" approaches could be used to produce arrays and single-crystalline nanotubes of other solid materials and semiconductors. Furthermore, the fabrication of multi-sheath nanotubes are described as well as nanotubes having multiple longitudinal segments.

  7. The breakage of nanopore in AAO template

    Science.gov (United States)

    Jia, X. R.; Wang, H.; Zhen, Y.

    2016-07-01

    In the present work, AAO template is fabricated in oxalic acid solution under a constant voltage by several steps. By the Bernoulli principle, the pressure on the wall of hole increases which lead to the breakage of nanopore as a result of the reducing effective migration rate of Al3+. The quantity of the breakage of nanopore rises with the increase of the concentration of Al3+. Further, nanopore is closed by oxide due to the decrease of effective migration rate of Al3+. Finally, a “nanoflower-like” shape can be observed in experiments.

  8. Nanoporous metal oxides templated by nanocrystalline cellulose

    OpenAIRE

    Ivanova, Alesja

    2015-01-01

    Porous materials play an important role in numerous environmental applications including energy storage, energy conversion and environmental remediation systems. Reducing structural features down to the nanoscale drastically alters materials properties and leads to the enhancement of materials performance. The successful fabrication of efficient functional materials requires a high degree of control over their morphology addressing the needs of target applications. The goal of this work...

  9. Electrochemical study of aluminum corrosion in boiling high purity water

    Science.gov (United States)

    Draley, J. E.; Legault, R. A.

    1969-01-01

    Electrochemical study of aluminum corrosion in boiling high-purity water includes an equation relating current and electrochemical potential derived on the basis of a physical model of the corrosion process. The work involved an examination of the cathodic polarization behavior of 1100 aluminum during aqueous oxidation.

  10. Graphene-aluminum nanocomposites

    International Nuclear Information System (INIS)

    Highlights: → We investigated the mechanical properties of aluminum and aluminum nanocomposites. → Graphene composite had lower strength and hardness compared to nanotube reinforcement. → Processing causes aluminum carbide formation at graphene defects. → The carbides in between grains is a source of weakness and lowers tensile strength. - Abstract: Composites of graphene platelets and powdered aluminum were made using ball milling, hot isostatic pressing and extrusion. The mechanical properties and microstructure were studied using hardness and tensile tests, as well as electron microscopy, X-ray diffraction and differential scanning calorimetry. Compared to the pure aluminum and multi-walled carbon nanotube composites, the graphene-aluminum composite showed decreased strength and hardness. This is explained in the context of enhanced aluminum carbide formation with the graphene filler.

  11. Graphene-aluminum nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Bartolucci, Stephen F., E-mail: stephen.bartolucci@us.army.mil [U.S. Army Benet Laboratories, Armaments Research Development and Engineering Center, Watervliet, NY 12189-4000 (United States); Paras, Joseph [U.S. Army Benet Laboratories, Armaments Research Development and Engineering Center, Watervliet, NY 12189-4000 (United States); Rafiee, Mohammad A. [Department of Mechanical Engineering and Materials Science, Rice University, Houston, TX 77005 (United States); Rafiee, Javad [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Lee, Sabrina; Kapoor, Deepak [U.S. Army Benet Laboratories, Armaments Research Development and Engineering Center, Watervliet, NY 12189-4000 (United States); Koratkar, Nikhil, E-mail: koratn@rpi.edu [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2011-10-15

    Highlights: {yields} We investigated the mechanical properties of aluminum and aluminum nanocomposites. {yields} Graphene composite had lower strength and hardness compared to nanotube reinforcement. {yields} Processing causes aluminum carbide formation at graphene defects. {yields} The carbides in between grains is a source of weakness and lowers tensile strength. - Abstract: Composites of graphene platelets and powdered aluminum were made using ball milling, hot isostatic pressing and extrusion. The mechanical properties and microstructure were studied using hardness and tensile tests, as well as electron microscopy, X-ray diffraction and differential scanning calorimetry. Compared to the pure aluminum and multi-walled carbon nanotube composites, the graphene-aluminum composite showed decreased strength and hardness. This is explained in the context of enhanced aluminum carbide formation with the graphene filler.

  12. Investigation of trap properties in high-k/metal gate p-type metal-oxide-semiconductor field-effect-transistors with aluminum ion implantation using random telegraph noise analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kao, Tsung-Hsien; Chang, Shoou-Jinn, E-mail: changsj@mail.ncku.edu.tw; Fang, Yean-Kuen; Huang, Po-Chin [Institute of Microelectronics and Department of Electrical Engineering, Advanced Optoelectronic Technology Center, Center for Micro/Nano Science and Technology, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan (China); Lai, Chien-Ming; Hsu, Chia-Wei; Chen, Yi-Wen; Cheng, Osbert [Central R and D Division, United Microelectronics Corporation, Ltd., Tainan Science-Based Industrial Park, Tainan 74145, Taiwan (China); Wu, Chung-Yi; Wu, San-Lein [Department of Electronic Engineering, Cheng Shiu University, 840 Chengcing Road, Niaosong, Kaohsiung 833, Taiwan (China)

    2014-08-11

    In this study, the impact of aluminum ion implantation (Al I/I) on random telegraph noise (RTN) in high-k/metal gate (HK/MG) p-type metal-oxide-semiconductor field-effect-transistors (pMOSFETs) was investigated. The trap parameters of HK/MG pMOSFETs with Al I/I, such as trap energy level, capture time and emission time, activation energies for capture and emission, and trap location in the gate dielectric, were determined. The configuration coordinate diagram was also established. It was observed that the implanted Al could fill defects and form a thin Al{sub 2}O{sub 3} layer and thus increase the tunneling barrier height for holes. It was also observed that the trap position in the Al I/I samples was lower due to the Al I/I-induced dipole at the HfO{sub 2}/SiO{sub 2} interface.

  13. Heterojunction solar cell with 6% efficiency based on an n-type aluminum-gallium-oxide thin film and p-type sodium-doped Cu2O sheet

    Science.gov (United States)

    Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

    2015-02-01

    In this paper, we describe efforts to enhance the efficiency of Cu2O-based heterojunction solar cells fabricated with an aluminum-gallium-oxide (Al-Ga-O) thin film as the n-type layer and a p-type sodium (Na)-doped Cu2O (Cu2O:Na) sheet prepared by thermally oxidizing copper sheets. The optimal Al content [X; Al/(Ga + Al) atomic ratio] of an AlX-Ga1-X-O thin-film n-type layer was found to be approximately 2.5 at. %. The optimized resistivity was approximately 15 Ω cm for n-type AlX-Ga1-X-O/p-type Cu2O:Na heterojunction solar cells. A MgF2/AZO/Al0.025-Ga0.975-O/Cu2O:Na heterojunction solar cell with 6.1% efficiency was fabricated using a 60-nm-thick n-type oxide thin-film layer and a 0.2-mm-thick Cu2O:Na sheet with the optimized resistivity.

  14. Cloning nanocrystal morphology with soft templates

    Science.gov (United States)

    Thapa, Dev Kumar; Pandey, Anshu

    2016-08-01

    In most template directed preparative methods, while the template decides the nanostructure morphology, the structure of the template itself is a non-general outcome of its peculiar chemistry. Here we demonstrate a template mediated synthesis that overcomes this deficiency. This synthesis involves overgrowth of silica template onto a sacrificial nanocrystal. Such templates are used to copy the morphologies of gold nanorods. After template overgrowth, gold is removed and silver is regrown in the template cavity to produce a single crystal silver nanorod. This technique allows for duplicating existing nanocrystals, while also providing a quantifiable breakdown of the structure - shape interdependence.

  15. Research on Properties of Ceramic Coating on 2Al2 Aluminum Alloy bv Plasma Microarc Oxidation%2Al2铝合金微弧氧化膜性能研究

    Institute of Scientific and Technical Information of China (English)

    郭虹; 宫廷; 黄树涛; 周丽

    2011-01-01

    Microarc oxidation (MAO) coating on 2A12 aluminum alloy was prepared in Na2SiO3 and Na2WO4 electrolytes, and the surface morphology, cross-sectional microstructure, wear resistance and micro-hardness and ceramic coatings have been studied in detail. The results show that the microarc oxidation surface treatment can form a dense ceramic coating on 2A12 aluminum alloy, which has good adhesion with aluminum alloy substrate. The concentration of Na2WO4solution has significant influence on the color, surface morphology, density and micro-hardness of ceramic coating, but not much influence on the thickness of the ceramic coating. Additionally, the addition of Na2WO4 into the base Na2SiO3 electrolyte resulted in the increase of the micro-hardness of the ceramic coating, furthermore, the micro-hardness of the ceramic coating increased with the increasing distance from the interface.%采用Na2 WO4和Na2SO3电解液对2Al2铝合金进行微弧氧化,研究了微弧氧化陶瓷膜表面形貌、截面组织、显微硬度及耐磨性等性能.结果表明,微弧氧化表面处理可以在2Al2铝合金表面形成致密并与基体结合良好的陶瓷膜,Na2WO4溶液浓度对陶瓷膜颜色、表面形貌、致密度和显微硬度都有影响,但对于陶瓷膜成膜厚度没有显著影响.同时,在Na2SiO3电解液中添加Na2WO4将会导致陶瓷膜显微硬度的增加,而且随着与界面距离的增大,陶瓷膜显微硬度逐渐增加.

  16. Preparation of Si Nanocrystals Using Anodic Porous Alumina Template Formed on Silicon Substrate

    Institute of Scientific and Technical Information of China (English)

    WU Jun-Hui; PU Lin; ZOU Jian-Ping; MEI Yong-Feng; ZHU Jian-Min; BAO Xi-Mao

    2000-01-01

    A novel technique to extend template application ofanodic porous alumina to Si has been reported. First, porous alumina template about 400 nm thick was prepared on silicon substrate by anodizing thin aluminum film with high purity of 99.99% in 15 wt.% sulfuric acid under a constant voltage of 20 V and at an electrolyte temperature of 5°C. Then, amorphous Si layer approximately 50nm in thickness was deposited onto the surface of template by using electron beam evaporation technique followed by an Xe ion beam bombardment, upon which as-coated Si layer at the pore mouth could be removed into pores smootlly. Three runs were performed by repeating above process of deposition and post bombardment. Finally, samples were annealed at 800°C for 30min in nitrogen.Transmission electron microscopy and x-ray diffraction analysis reveal Si nanocrystals with a size of 15-20nm being formed in the pores of template.

  17. 软模板法合成介孔片层组成的氧化镍微球及吸附研究%Synthesis and adsorption study of mesoporous layer composing nickel oxide microspheres by soft template

    Institute of Scientific and Technical Information of China (English)

    吕仁江; 王珊珊; 李英杰; 高立娣; 陈世界; 徐红梅; 于春杰

    2015-01-01

    The nickel nitrate acted as the nickel source,the mixture solution of water and alcohol as solvent,and P123 as soft template,the nickel oxide microspheres with mesoporous layer structure were synthesized by precursor route and solvothermal method,and meanwhile the influence of different reaction time and reaction temperature for prepared NiO microspheres were also discussed.The obtained samples were characterized and analysed by the X-ray diffraction ( XRD ), scanning electron microscope ( SEM ), transmission electric microscope ( TEM ), N2 adsorption-desorption.The results show that the as-prepared NiO microspheres possess mesoporous layer structure, the specific surface area reaches 37.6 m2/g,moreover,the size increasing and shape influence of NiO microspheres mainly attribute to the increasing of the solvothermal time and reaction temperature.Meanwhile,the absorption test of synthesized NiO microspheres with mesoporous layer structure for congo red aqueous solution was also exploited,and there is good adsorption performance,and the removal rate can be up to 96.92%.%以硝酸镍为镍源,水和乙醇混合液为溶剂,P123为软模板.采用前驱体路线和溶剂热法合成了介孔片层组成的具有特殊形貌的氧化镍微球,同时讨论了不同温度和时间对氧化镍微球形貌的影响.利用XRD,SEM,TEM和N2吸附-脱附等手段对样品进行了分析表征.结果表明,所合成的氧化镍材料具有介孔结构,比表面积为37.16 m2/g,溶剂热时间的增加和反应温度的升高都有利于氧化镍晶粒长大和形貌变化.与此同时,在水溶液中氧化镍微球对刚果红染料呈现了较好的吸附性能,去除率最高可达96.92%.

  18. Guangdong Aluminum to Raise RMB 3 billion for New Production Base in Guizhou

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>On July 7, a loan signing ceremony was held between the Guangdong Aluminum Group, China Construction Bank, Hua Xia Bank and Guangzhou Bank Consortium. It is reported that these banks will provide Guangdong Aluminum Group with RMB 30 billion for an alu-minum oxide and supporting bauxite mining project in Guizhou.

  19. Brain templates and atlases.

    Science.gov (United States)

    Evans, Alan C; Janke, Andrew L; Collins, D Louis; Baillet, Sylvain

    2012-08-15

    The core concept within the field of brain mapping is the use of a standardized, or "stereotaxic", 3D coordinate frame for data analysis and reporting of findings from neuroimaging experiments. This simple construct allows brain researchers to combine data from many subjects such that group-averaged signals, be they structural or functional, can be detected above the background noise that would swamp subtle signals from any single subject. Where the signal is robust enough to be detected in individuals, it allows for the exploration of inter-individual variance in the location of that signal. From a larger perspective, it provides a powerful medium for comparison and/or combination of brain mapping findings from different imaging modalities and laboratories around the world. Finally, it provides a framework for the creation of large-scale neuroimaging databases or "atlases" that capture the population mean and variance in anatomical or physiological metrics as a function of age or disease. However, while the above benefits are not in question at first order, there are a number of conceptual and practical challenges that introduce second-order incompatibilities among experimental data. Stereotaxic mapping requires two basic components: (i) the specification of the 3D stereotaxic coordinate space, and (ii) a mapping function that transforms a 3D brain image from "native" space, i.e. the coordinate frame of the scanner at data acquisition, to that stereotaxic space. The first component is usually expressed by the choice of a representative 3D MR image that serves as target "template" or atlas. The native image is re-sampled from native to stereotaxic space under the mapping function that may have few or many degrees of freedom, depending upon the experimental design. The optimal choice of atlas template and mapping function depend upon considerations of age, gender, hemispheric asymmetry, anatomical correspondence, spatial normalization methodology and disease

  20. 阳极氧化法制备多孔氧化铝膜的形成过程研究%Investigation on the growth sequence of porous anodic aluminum oxide films by two-step anodization

    Institute of Scientific and Technical Information of China (English)

    刘海凤; 路丙强; 梁冬林; 魏水强; 苟凯佩; 王凡; 文衍宣

    2012-01-01

    采用阳极氧化技术,研究了电压对多孔氧化铝膜生长过程的影响.使用扫描电镜( SEM)对在草酸-水-乙醇体系中形成的多孔氧化铝膜形貌进行观测.结果表明,在第二步氧化过程中,在40V氧化电压下,多孔氧化铝膜的有序度和孔径随反应时间延长而降低;在80 V下,经过长时间反应,AAO膜表面腐蚀严重,难以获得平整的多孔结构.预氧化过程所形成的薄氧化层有效保护了多孔氧化铝表面,同时对多孔结构具有短距离诱导作用.改变氧化电压、电解质浓度和反应时间,有序孔排列的结构参数也有所改变.高电场下,孔道的相互作用促进了其生长分化,形成了两种不同的孔道结构.%The detailed growth processes of porous anodic aluminum oxide films influenced by the applied voltage were studied via anodization method. The appearance of the porous anodic aluminum oxide films formed in oxalic acid-water-ethanol solution was studied by SEM. At the second anodization step, the ordering degree and pore size of oxide films decreased at 40 V, while the rough surface of AAO by severe corrosion was obtained at 80 V. Whereas, the surface oxide layer generated by pre-anodization provided effective protection at the early stage of high-voltage anodization, and guided the formation of ordered pores array in short range. The structural parameters of ordered pores array were dependent on the applied voltage, electrolyte concentration and reaction time. At high applied voltage, the cause of interaction forces between neighboring pores enhances the differentiation of pore growth, and hence two different pores growth behaviors in the internal and surface of AAO membrane are observed.