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Sample records for anode interfacial layer

  1. Aryl end-capped quaterthiophenes applied as anode interfacial layers in inverted organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Heiskanen, Juha P., E-mail: juha.heiskanen@oulu.fi [Department of Chemistry, P.O. Box 3000, FI-90014 University of Oulu (Finland); Manninen, Venla M. [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere (Finland); Pankov, Dmitri [Department of Chemistry, P.O. Box 3000, FI-90014 University of Oulu (Finland); Omar, Walaa A.E. [Department of Chemistry, P.O. Box 3000, FI-90014 University of Oulu (Finland); Department of Chemistry and Mathematics, Faculty of Petroleum and Mining Engineering, Suez University, Suez 43721 (Egypt); Kastinen, Tuuva; Hukka, Terttu I.; Lemmetyinen, Helge J. [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere (Finland); Hormi, Osmo E.O. [Department of Chemistry, P.O. Box 3000, FI-90014 University of Oulu (Finland)

    2015-01-01

    Four aryl end-capped quaterthiophene derivatives were synthesized and their material properties were studied by computational, spectroscopic, electrochemical, and thermoanalytical methods. Compounds were applied as interfacial layers between the bulk heterojunction active layer and Ag anode in inverted organic solar cells. Results show that p-cyanophenyl end-capped quaterthiophene with hexyl side chains increases both the short circuit current density and power conversion efficiency notably compared to reference interlayer material, tris-(8-hydroxyquinoline)aluminum. The improved cell performance was attributed to the optimal positions of the highest occupied molecular orbital and the lowest unoccupied molecular orbital (LUMO) of this material, relative to those of the photoactive electron donor poly(3-hexylthiophene) and Ag anode, and evenly distributed LUMO. In addition, the use of these materials as an anode interfacial layer increases the absorption of the solar cell, which could contribute to the formation of excitons and additional current production by the cell. - Highlights: • Aryl end-capped oligothiophenes were synthesized in good overall yields. • Materials could be applied as anode interfacial layers in organic solar cells. • Computational, spectroscopic, and electrochemical analyses support conclusions. • Substitution patterns determine HOMO and LUMO levels of interfacial material. • Improved cell performance was attributed mainly to optimal HOMO and LUMO levels.

  2. Aryl end-capped quaterthiophenes applied as anode interfacial layers in inverted organic solar cells

    International Nuclear Information System (INIS)

    Four aryl end-capped quaterthiophene derivatives were synthesized and their material properties were studied by computational, spectroscopic, electrochemical, and thermoanalytical methods. Compounds were applied as interfacial layers between the bulk heterojunction active layer and Ag anode in inverted organic solar cells. Results show that p-cyanophenyl end-capped quaterthiophene with hexyl side chains increases both the short circuit current density and power conversion efficiency notably compared to reference interlayer material, tris-(8-hydroxyquinoline)aluminum. The improved cell performance was attributed to the optimal positions of the highest occupied molecular orbital and the lowest unoccupied molecular orbital (LUMO) of this material, relative to those of the photoactive electron donor poly(3-hexylthiophene) and Ag anode, and evenly distributed LUMO. In addition, the use of these materials as an anode interfacial layer increases the absorption of the solar cell, which could contribute to the formation of excitons and additional current production by the cell. - Highlights: • Aryl end-capped oligothiophenes were synthesized in good overall yields. • Materials could be applied as anode interfacial layers in organic solar cells. • Computational, spectroscopic, and electrochemical analyses support conclusions. • Substitution patterns determine HOMO and LUMO levels of interfacial material. • Improved cell performance was attributed mainly to optimal HOMO and LUMO levels

  3. UV-treated graphene oxide as anode interfacial layers for P3HT : PCBM solar cells

    Science.gov (United States)

    Cheng, Cheng-En; Tsai, Cheng-Wei; Pei, Zingway; Lin, Tsung-Wu; Chang, Chen-Shiung; Shih-Sen Chien, Forest

    2015-06-01

    Solution-processable graphene oxide (GO) ultrathin films were introduced as anode interfacial layers (AILs) for polymer solar cells (PSCs). The photovoltaic performance of PSCs containing thermal- and UV-treated GO was comparable to that of PSCs with conventional poly(3,4-ethyledioxythiphene):poly(styrenesulfonate) AILs. UV treatment induced the surface activation of GO; an increase in the work function of UV-treated GO improved the energy band alignment at the GO/poly(3-hexylthiophene) interface, which accounted for the efficient hole collection and photovoltaic performance of PSCs with treated GO.

  4. UV-treated graphene oxide as anode interfacial layers for P3HT : PCBM solar cells

    International Nuclear Information System (INIS)

    Solution-processable graphene oxide (GO) ultrathin films were introduced as anode interfacial layers (AILs) for polymer solar cells (PSCs). The photovoltaic performance of PSCs containing thermal- and UV-treated GO was comparable to that of PSCs with conventional poly(3,4-ethyledioxythiphene):poly(styrenesulfonate) AILs. UV treatment induced the surface activation of GO; an increase in the work function of UV-treated GO improved the energy band alignment at the GO/poly(3-hexylthiophene) interface, which accounted for the efficient hole collection and photovoltaic performance of PSCs with treated GO. (paper)

  5. Interfacial effect on the electrochemical properties of the layered graphene/metal sulfide composites as anode materials for Li-ion batteries

    Science.gov (United States)

    Lv, Yagang; Chen, Biao; Zhao, Naiqin; Shi, Chunsheng; He, Chunnian; Li, Jiajun; Liu, Enzuo

    2016-09-01

    The layered graphene/metal sulfide composites exhibit excellent electrochemical properties as anode materials for lithium ion battery, due to the synergistic effect between metal sulfide and graphene which still needs to be further understood. In this study, Li adsorption and diffusion on MoS2 and SnS2 monolayers and Li2S surface, as well as at their interfaces with graphene, are systematically investigated through first-principles calculations. The analysis of charge density difference, Bader charge, and density of states indicates that the adsorbed Li atoms interact with both the S atoms at metal sulfide surfaces and C atoms in graphene, resulting in larger Li adsorption energies at the interfaces compared with that on the corresponding surfaces, but with almost no enhancement of the energy barriers for Li atom diffusion. The enhanced Li adsorption capability at Li2S/G interface contributes to the extra storage capacity of graphene/metal sulfide composites. Furthermore, the synergistic mechanism between metal sulfide and graphene is revealed. Moreover, band structure analysis shows the electronic conductivity is enhanced with the incorporation of graphene. The results corroborate the interfacial pseudocapacity-like Li atom storage mechanism, and are helpful for the design of layered graphene/metal sulfide composites as anode materials for lithium ion batteries.

  6. Organic photovoltaic device with interfacial layer and method of fabricating same

    Science.gov (United States)

    Marks, Tobin J.; Hains, Alexander W.

    2013-03-19

    An organic photovoltaic device and method of forming same. In one embodiment, the organic photovoltaic device has an anode, a cathode, an active layer disposed between the anode and the cathode; and an interfacial layer disposed between the anode and the active layer, the interfacial layer comprising 5,5'-bis[(p-trichlorosilylpropylphenyl)phenylamino]-2,2'-bithiophene (PABTSi.sub.2).

  7. Understanding the interfacial phenomena of a 4.7 V and 55 °C Li-ion battery with Li-rich layered oxide cathode and grap2hite anode and its correlation to high-energy cycling performance

    Science.gov (United States)

    Pham, Hieu Quang; Hwang, Eui-Hyung; Kwon, Young-Gil; Song, Seung-Wan

    2016-08-01

    Research progress of high-energy performance and interfacial phenomena of Li1.13Mn0.463Ni0.203Co0.203O2 cathode and graphite anode in a 55 °C full-cell under an aggressive charge cut-off voltage to 4.7 V (4.75 V vs. Li/Li+) is reported. Although anodic instability of conventional electrolyte is the critical issue on high-voltage and high-temperature cell operation, interfacial phenomena and the solution to performance improvement have not been reported. Surface spectroscopic evidence revealed that structural degradation of both cathode and anode materials, instability of surface film at cathode, and metal-dissolution from cathode and -deposition at anode, and a rise of interfacial resistance with high-voltage cycling in 55 °C conventional electrolyte are resolved by the formation of a stable surface film with organic/inorganic mixtures at cathode and solid electrolyte interphase (SEI) at anode using blended additives of fluorinated linear carbonate and vinylene carbonate. As a result, significantly improved cycling stability of 77% capacity retention delivering 227-174 mAhg-1 after 50 cycles is obtained, corresponding to 819-609 Wh per kg of cathode active material. Interfacial stabilization approach would pave the way of controlling the performance and safety, and widening the practical application of Li-rich layered oxide cathode materials and high-voltage electrolyte materials in various high-energy density Li-ion batteries.

  8. Anode interfacial tuning via electron-blocking/hole-transport layers and indium tin oxide surface treatment in bulk-heterojunction organic photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Hains, Alexander W.; Liu, Jun; Martinson, Alex B.F.; Irwin, Michael D.; Marks, Tobin J. [Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois (United States)

    2010-02-22

    The effects of anode/active layer interface modification in bulk-heterojunction organic photovoltaic (OPV) cells is investigated using poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and/or a hole-transporting/electron-blocking blend of 4,4'-bis[(p-trichlorosilylpropylphenyl)-phenylamino]biphenyl (TPDSi{sub 2}) and poly[9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine] (TFB) as interfacial layers (IFLs). Current-voltage data in the dark and AM1.5G light show that the TPDSi{sub 2}:TFB IFL yields MDMO-PPV:PCBM OPVs with substantially increased open-circuit voltage (V{sub oc}), power conversion efficiency, and thermal stability versus devices having no IFL or PEDOT:PSS. Using PEDOT:PSS and TPDSi{sub 2}:TFB together in the same cell greatly reduces dark current and produces the highest V{sub oc} (0.91 V) by combining the electron-blocking effects of both layers. ITO anode pre-treatment was investigated by X-ray photoelectron spectroscopy to understand why oxygen plasma, UV ozone, and solvent cleaning markedly affect cell response in combination with each IFL. O{sub 2} plasma and UV ozone treatment most effectively clean the ITO surface and are found most effective in preparing the surface for PEDOT:PSS deposition; UV ozone produces optimum solar cells with the TPDSi{sub 2}:TFB IFL. Solvent cleaning leaves significant residual carbon contamination on the ITO and is best followed by O{sub 2} plasma or UV ozone treatment. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  9. Interfacial chemistry of zinc anodes for reinforced concrete structures

    Energy Technology Data Exchange (ETDEWEB)

    Covino, B.S. Jr.; Bullard, S.J.; Cramer, S.D.; Holcomb, G.R. [Dept. of Energy, Albany, OR (United States). Albany Research Center; McGill, G.E.; Cryer, C.B. [Oregon Dept. of Transportation, Salem, OR (United States); Stoneman, A. [International Lead Zinc Research Organization, Research Triangle Park, NC (United States); Carter, R.R. [California Dept. of Transportation, Sacramento, CA (United States)

    1997-12-01

    Thermally-sprayed zinc anodes are used in both galvanic and impressed current cathodic protection systems for reinforced concrete structures. The Albany Research Center, in collaboration with the Oregon Department of Transportation, has been studying the effect of electrochemical aging on the bond strength of zinc anodes for bridge cathodic protection systems. Changes in anode bond strength and other anode properties can be explained by the chemistry of the zinc-concrete interface. The chemistry of the zinc-concrete interface in laboratory electrochemical aging studies is compared with that of several bridges with thermal-sprayed zinc anodes and which have been in service for 5 to 10 years using both galvanic and impressed current cathodic protection systems. The bridges are the Cape Creek Bridge on the Oregon coast and the East Camino Undercrossing near Placerville, CA. Also reported are interfacial chemistry results for galvanized steel rebar from the 48 year old Longbird Bridge in Bermuda.

  10. Mechanics of inhomogeneous turbulence and interfacial layers

    OpenAIRE

    Hunt, J.C.R; Eames, I; Westerweel, J.

    2006-01-01

    The mechanics of inhomogeneous turbulence in and adjacent to interfacial layers bounding turbulent and non-turbulent regions are analysed. Different mechanisms are identified according to the straining by the turbulent eddies in relation to the strength of the mean shear adjacent to, or across, the interfacial layer. How the turbulence is initiated and the topology of the region of turbulence are also significant factors. Specifically the cases of a layer of turbulence bounded on one, or two,...

  11. Anode glow and double layer in DC magnetron anode plasma

    International Nuclear Information System (INIS)

    Sputtering magnetron is widely used device in research and industry alike. DC planar magnetron employs series of magnets to create magnetic field above the electrode surface which traps electrons in closed E-bar x B-bar drift. Similar device used in reversed polarity power was reported for use in various applications. In contrast to its normal counterpart there is no closed drift effect in there. This device has very limited understanding. We here investigate this device for its discharge properties. Our device is dominated by anode glow. The anode glow is expected to have the electron sheath which provides energy to electron to excite the neutrals. Where as many experimental studies have been reported for anode glow and anode double layer, many of them uses auxiliary anode in the discharge. Most of the cases anode double layer (fire ball/fire rod) is small structures very near to anode surface which in itself is required to be small. The DC planar magnetron biased in reverse polarity have glow only near anode. Measurements confirm it as anode glow and the presence of electrons sheath is proven. The double layer structure was observed and measured in two mutually perpendicular directions. The double layer shows sub MHz oscillation that is typical of the unstable anode double layer. The dimension of anode glow is relatively large and is primarily in magnetic field free region making it easy to probe. The potential structure still shows large cathode fall but surprisingly visible cathode glow is not present. The device operates very stable for pressure bellow 0.01 mbar. But it shows instabilities such as unstable anode double layer above said pressure. (author)

  12. TFB:TPDSi2 interfacial layer usable in organic photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Iobin J. (Evanston, IL); Hains, Alexander W. (Evanston, IL)

    2011-02-15

    The present invention, in one aspect, relates to a solar cell. In one embodiment, the solar cell includes an anode; an active organic layer comprising an electron-donating organic material and an electron-accepting organic material; and an interfacial layer formed between the anode and active organic layer, where the interfacial layer comprises a hole-transporting polymer characterized with a hole-mobility higher than that of the electron-donating organic material in the active organic layer, and a small molecule that has a high hole-mobility and is capable of crosslinking on contact with air.

  13. Modeling interfacial liquid layers on environmental ices

    OpenAIRE

    Kuo, M H; S. G. Moussa; V. F. McNeill

    2011-01-01

    Interfacial layers on ice significantly influence air-ice chemical interactions. In solute-containing aqueous systems, a liquid brine may form upon freezing due to the exclusion of impurities from the ice crystal lattice coupled with freezing point depression in the concentrated brine. The brine may be segregated to the air-ice interface where it creates a surface layer, in micropockets, or at grain boundaries or triple junctions.

    We present a model for brines and their a...

  14. Modeling interfacial liquid layers on environmental ices

    Directory of Open Access Journals (Sweden)

    M. H. Kuo

    2011-09-01

    Full Text Available Interfacial layers on ice significantly influence air-ice chemical interactions. In solute-containing aqueous systems, a liquid brine may form upon freezing due to the exclusion of impurities from the ice crystal lattice coupled with freezing point depression in the concentrated brine. The brine may be segregated to the air-ice interface where it creates a surface layer, in micropockets, or at grain boundaries or triple junctions.

    We present a model for brines and their associated liquid layers in environmental ice systems that is valid over a wide range of temperatures and solute concentrations. The model is derived from fundamental equlibrium thermodynamics and takes into account nonideal solution behavior in the brine, partitioning of the solute into the ice matrix, and equilibration between the brine and the gas phase for volatile solutes. We find that these phenomena are important to consider when modeling brines in environmental ices, especially at low temperatures. We demonstrate its application for environmentally important volatile and nonvolatile solutes including NaCl, HCl, and HNO3. The model is compared to existing models and experimental data from literature where available. We also identify environmentally relevant regimes where brine is not predicted to exist, but the QLL may significantly impact air-ice chemical interactions. This model can be used to improve the representation of air-ice chemical interactions in polar atmospheric chemistry models.

  15. Adiabatic waves along interfacial layers near the critical point

    CERN Document Server

    Gouin, Henri

    2008-01-01

    Near the critical point, isothermal interfacial zones are investigated starting from a non-local density of energy. From the equations of motion of thermocapillary fluids, we point out a new kind of adiabatic waves propagating along the interfacial layers. The waves are associated with the second derivatives of densities and propagate with a celerity depending on the proximity of the critical point.

  16. Anodization of carbon fibers on interfacial mechanical properties of epoxy matrix composites.

    Science.gov (United States)

    Park, Soo-Jin; Chang, Yong-Hwan; Kim, Yeong-Cheol; Rhee, Kyong-Yop

    2010-01-01

    The influence of anodic oxidation on the mechanical interfacial properties of carbon-fiber-reinforced epoxy resin composites was investigated. The surface properties of the anodized carbon fibers were studied through the measurement of contact angles and through SEM, XPS, and FT-IR analyses. The mechanical interfacial properties of the composites were studied through measurements of interlaminar shear strength (ILSS), critical stress intensity factor (K(IC)), and critical strain energy release rate (G(IC)). It was shown that the surface functional groups containing oxygen on the anodized carbon fibers exert great effects on the surface energetics of fibers and the mechanical interfacial properties, e.g., ILSS, of the resulting composites. Contact angle measurements based on the wicking rate of a test liquid showed that anodic oxidation lead to an increase in the surface free energy of the carbon fibers, mainly in its specific (or polar) component. In terms of surface energetics, it was found that wetting played an important role in increasing the degree of adhesion at interfaces between the fibers and the resin matrices of the composites. PMID:20352820

  17. 1,3-dioxolane pretreatment to improve the interfacial characteristics of a lithium anode

    Institute of Scientific and Technical Information of China (English)

    DING Fei; LIU Yuwen; HU Xinguo

    2006-01-01

    1,3-dioxolane (DOL) was originally used to pretreat a lithium metal electrode to improve its interfacial characteristics. Electrochemical impedance spectra (EIS) measurements revealed that, after the DOL pretreatment, the lithium electrode had better interfacial stability during immersion in electrolyte and as repeated charge/discharge cycles. It was proved by SEM that the pretreated one has smoother morphology and less dendrite after repeated charge/discharge cycles.Consequentially, benefiting from the better interface characteristics of the lithium electrode, the rechargeable lithium cell with a DOL-pretreated lithium anode had the obviously enhanced discharging performance and better cyclability.

  18. Artificially MoO3 graded ITO anodes for acidic buffer layer free organic photovoltaics

    Science.gov (United States)

    Lee, Hye-Min; Kim, Seok-Soon; Kim, Han-Ki

    2016-02-01

    We report characteristics of MoO3 graded ITO anodes prepared by a RF/DC graded sputtering for acidic poly(3,4-ethylene dioxylene thiophene):poly(styrene sulfonic acid) (PEDOT:PSS)-free organic solar cells (OSCs). Graded sputtering of the MoO3 buffer layer on top of the ITO layer produced MoO3 graded ITO anodes with a sheet resistance of 12.67 Ω/square, a resistivity of 2.54 × 10-4 Ω cm, and an optical transmittance of 86.78%, all of which were comparable to a conventional ITO anode. In addition, the MoO3 graded ITO electrode showed a greater work function of 4.92 eV than that (4.6 eV) of an ITO anode, which is beneficial for hole extraction from an organic active layer. Due to the high work function of MoO3 graded ITO electrodes, the acidic PEDOT:PSS-free OSCs fabricated on the MoO3 graded ITO electrode exhibited a power conversion efficiency 3.60% greater than that of a PEDOT:PSS-free OSC on the conventional ITO anode. The successful operation of PEDOT:PSS-free OSCs indicates simpler fabrication steps for cost-effective OSCs and elimination of interfacial reactions caused by the acidic PEDOT:PSS layer for reliable OSCs.

  19. Anodic Oxidation of Ultra-Thin Ti Layers on ITO Substrates and their Application in Organic Electronic Memory Elements

    International Nuclear Information System (INIS)

    In this work, controlled anodic oxidation is reported for ultra-thin (3 nm thick) titanium layers on indium tin oxide (ITO) coated glass substrates. A physical explanation is also provided for the origin of the delamination process of the Ti during the anodic oxidation. The properties of the fabricated layers are studied using electrochemical impedance spectroscopy (EIS) and X-ray Photoelectron Spectroscopy (XPS). In addition, one intriguing application is demonstrated for the anodized layers: their use as an interfacial barrier in organic diodes. Diodes containing an electrochemically fabricated TiO2 barrier layer exhibit clear room temperature negative differential resistance (NDR) and a peak-to-valley current ratio (PVCR) of 3.6. The reference diodes without the TiO2 layer show normal diode characteristics with no observable NDR. The NDR diodes have potential applications as memory elements for large-area electronics

  20. High performance CNT point emitter with graphene interfacial layer

    International Nuclear Information System (INIS)

    Carbon nanotubes (CNTs) have great potential in the development of high-power electron beam sources. However, for such a high-performance electronic device, the electric and thermal contact problem between the metal and CNTs must be improved. Here, we report graphene as an interfacial layer between the metal and CNTs to improve the interfacial contact. The interfacial graphene layer results in a dramatic decrease of the electrical contact resistance by an order of 2 and an increase of the interfacial thermal conductivity by 16%. Such a high improvement in the electrical and thermal interface leads to superior field emission performance with a very low turn-on field of 1.49 V μm−1 at 10 μA cm−2 and a threshold field of 2.00 V μm−1 at 10 mA cm−2, as well as the maximum current of 16 mA (current density of 2300 A cm−2). (paper)

  1. Amine-terminated ionic liquid functionalized carbon nanotubes for enhanced interfacial electron transfer of Shewanella putrefaciens anode in microbial fuel cells

    Science.gov (United States)

    Wei, Huan; Wu, Xiao-Shuai; Zou, Long; Wen, Guo-Yun; Liu, Ding-Yu; Qiao, Yan

    2016-05-01

    An amine-terminated ionic liquid (IL-NH2) is applied to functionalize carbon nanotubes (CNTs) for improving the interfacial electron transfer of Shewanella putrefaciens (S. putrefaciens) anode in Microbial fuel cells (MFCs). The introduction of thin layer of ILs does not change the morphology of CNTs a lot but increases surface positive charges as well as nitrogen functional groups of the CNTs based anode. The CNT-IL composite not only improves the adhesion of S. putrefaciens cells but also promotes both of the flavin-mediated and the direct electron transfer between the S. putrefaciens cells and the anode. It is interesting that the CNT-IL is more favorable for the mediated electron transfer than for the direct electron transfer. The CNT-IL/carbon cloth anode delivers 3-fold higher power density than that of CNT anode and shows great long-term stability in the batch-mode S. putrefaciens MFCs. This CNT-IL could be a promising anode material for high performance MFCs.

  2. Low cost fuel cell diffusion layer configured for optimized anode water management

    Science.gov (United States)

    Owejan, Jon P; Nicotera, Paul D; Mench, Matthew M; Evans, Robert E

    2013-08-27

    A fuel cell comprises a cathode gas diffusion layer, a cathode catalyst layer, an anode gas diffusion layer, an anode catalyst layer and an electrolyte. The diffusion resistance of the anode gas diffusion layer when operated with anode fuel is higher than the diffusion resistance of the cathode gas diffusion layer. The anode gas diffusion layer may comprise filler particles having in-plane platelet geometries and be made of lower cost materials and manufacturing processes than currently available commercial carbon fiber substrates. The diffusion resistance difference between the anode gas diffusion layer and the cathode gas diffusion layer may allow for passive water balance control.

  3. High-Performance Si/SiOx Nanosphere Anode Material by Multipurpose Interfacial Engineering with Black TiO2-x.

    Science.gov (United States)

    Bae, Juhye; Kim, Dae Sik; Yoo, Hyundong; Park, Eunjun; Lim, Young-Geun; Park, Min-Sik; Kim, Young-Jun; Kim, Hansu

    2016-02-24

    Silicon oxides (SiOx) have attracted recent attention for their great potential as promising anode materials for lithium ion batteries as a result of their high energy density and excellent cycle performance. Despite these advantages, the commercial use of these materials is still impeded by low initial Coulombic efficiency and high production cost associated with a complicated synthesis process. Here, we demonstrate that Si/SiOx nanosphere anode materials show much improved performance enabled by electroconductive black TiO2-x coating in terms of reversible capacity, Coulombic efficiency, and thermal reliability. The resulting anode material exhibits a high reversible capacity of 1200 mAh g(-1) with an excellent cycle performance of up to 100 cycles. The introduction of a TiO2-x layer induces further reduction of the Si species in the SiOx matrix phase, thereby increasing the reversible capacity and initial Coulombic efficiency. Besides the improved electrochemical performance, the TiO2-x coating layer plays a key role in improving the thermal reliability of the Si/SiOx nanosphere anode material at the same time. We believe that this multipurpose interfacial engineering approach provides another route toward high-performance Si-based anode materials on a commercial scale. PMID:26820496

  4. Spark protection layers for CMOS pixel anode chips in MPGDs

    NARCIS (Netherlands)

    Bilevych, Y.; Blanco Carballo, V.M.; Chefdeville, M.A.; Colas, P.; Delagnes, E.; Fransen, M.; Graaff, van der H.; Koppert, W.J.C.; Melai, J.; Salm, C.; Schmitz, J.; Timmermans, J.; Wyrsch, N.

    2011-01-01

    In this work we have investigated the functioning of high resistivity amorphous silicon and silicon-rich nitride layers as a protection against discharges in Micro-Patterned Gaseous Detectors (MPGDs).When the anode is protected by a high resistivity layer, discharge signals are limited in charge. A

  5. Interface feature characterization and Schottky interfacial layer confirmation of TiO2 nanotube array film

    Science.gov (United States)

    Li, Hongchao; Tang, Ningxin; Yang, Hongzhi; Leng, Xian; Zou, Jianpeng

    2015-11-01

    We report here characterization of the interfacial microstructure and properties of titanium dioxide (TiO2) nanotube array films fabricated by anodization. Field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD), nanoindentation, atomic force microscopy (AFM), selected area electron diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM) were used to characterize the interface of the film. With increasing annealing temperature from 200 °C to 800 °C, the interfacial fusion between the film and the Ti substrate increased. The phase transformation of the TiO2 nanotube film from amorphous to anatase to rutile took place gradually; as the phase transformation progressed, the force needed to break the film increased. The growth of TiO2 nanotube arrays occurs in four stages: barrier layer formation, penetrating micropore formation, regular nanotube formation, and nanofiber formation. The TiO2 nanotubes grow from the Schottky interface layer rather than from the Ti substrate. The Schottky interface layer's thickness of 35-45 nm was identified as half the diameter of the corresponding nanotube, which shows good agreement to the Schottky interface layer growth model. The TiO2 nanotube film was amorphous and the Ti substrate was highly crystallized with many dislocation walls.

  6. Improved Reliability of Small Molecule Organic Solar Cells by Double Anode Buffer Layers

    Directory of Open Access Journals (Sweden)

    Pao-Hsun Huang

    2014-01-01

    Full Text Available An optimized hybrid planar heterojunction (PHJ of small molecule organic solar cells (SM-OSCs based on copper phthalocyanine (CuPc as donor and fullerene (C60 as acceptor was fabricated, which obviously enhanced the performance of device by sequentially using both MoO3 and pentacene as double anode buffer layers (ABL, also known as hole extraction layer (HEL. A series of the vacuum-deposited ABL, acting as an electron and exciton blocking layer, were examined for their characteristics in SM-OSCs. The performance and reliability were compared between conventional ITO/ABL/CuPc/C60/BCP/Ag cells and the new ITO/double ABL/CuPc/C60/BCP/Ag cells. The effect on the electrical properties of these materials was also investigated to obtain the optimal thickness of ABL. The comparison shows that the modified cell has an enhanced reliability compared to traditional cells. The improvement of lifetime was attributed to the idea of double layers to prevent humidity and oxygen from diffusing into the active layer. We demonstrated that the interfacial extraction layers are necessary to avoid degradation of device. That is to say, in normal temperature and pressure, a new avenue for the device within double buffer layers has exhibited the highest values of open circuit voltage (Voc, fill factor (FF, and lifetime in this work compared to monolayer of ABL.

  7. Spark protection layers for CMOS pixel anode chips in MPGDs

    Energy Technology Data Exchange (ETDEWEB)

    Bilevych, Y. [Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Blanco Carballo, V.M. [Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); University of Twente/Mesa Institute for Nanotechnology, Hogekamp 3214, 7500 AE Enschede (Netherlands); Chefdeville, M. [Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Colas, P.; Delagnes, E. [Irfu, CEA Saclay, F91191 Gif sur Yvette Cedex (France); Fransen, M. [Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Graaf, H. van der, E-mail: vdgraaf@nikhef.n [Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Koppert, W.J.C. [Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Melai, J.; Salm, C.; Schmitz, J. [University of Twente/Mesa Institute for Nanotechnology, Hogekamp 3214, 7500 AE Enschede (Netherlands); Timmermans, J. [Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Wyrsch, N. [Ecole Polytechnique Federale de Lausanne (EPFL), Institute of Microengineering (IMT), Breguet 2, CH-2000 Neuchatel (Switzerland)

    2011-02-11

    In this work we have investigated the functioning of high resistivity amorphous silicon and silicon-rich nitride layers as a protection against discharges in Micro-Patterned Gaseous Detectors (MPGDs). When the anode is protected by a high resistivity layer, discharge signals are limited in charge. A signal reduction is expected when the layers are too thick; simulations presented in this paper indicate that layers up to 10 {mu}m thick can be applied without significantly degrading the detector performance. Layers of amorphous silicon and silicon-rich nitride have been deposited on top of Timepix and Medipix2 chips in GridPix detectors; with this, chips survive naturally occurring as well as intentionally produced discharges.

  8. Properties of Ultra-Thin Hafnium Oxide and Interfacial Layer Deposited by Atomic Layer Deposition

    Institute of Scientific and Technical Information of China (English)

    Taeho Lee; Young-Bae Kim; Kyung-Il Hong; Duck-Kyun Choi; Jinho Ahn

    2004-01-01

    Ultra-thin hafnium-oxide gate dielectric films deposited by atomic layer deposition technique using HfCl4 and H2O precursor on a hydrogen-terminated Si substrate were investigated. X-ray photoelectron spectroscopy indicates that the interface layer is Hf-silicate rather than phase separated Hf-silicide and silicon oxide structure. The Hf-silicate interfacial layer partially changes into SiOx after high temperature annealing, resulting in a complex HfO2-silicate-SiOx dielectric structure. Electrical measurements confirms that HfO2 on Si is stable up to 700 ℃ for 30 s under N2 ambient.

  9. Anode layer in a high-current arc in atmospheric pressure nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Nemchinsky, Valerian A [ESAB Welding and Cutting Products and Francis Marion University, Florence, SC 29501 (United States)

    2005-11-21

    An anode layer in a high-current atmospheric nitrogen arc was modelled. Calculations were made in a one-dimensional approximation at current densities in the range 500-3000 A cm{sup -2}. Two-temperature approximation was used. We calculated the distributions of both electron and heavy particle temperatures, the concentrations of charged and neutral particles and the electric field inside the anode layer. It was shown that for the conditions that exist in the anode layer of a high-current atmospheric pressure arc in nitrogen (a) the concentration of the molecular ions is negligible and (b) the concentration of atoms exceeds the concentration of molecules everywhere in the anode layer except in a narrow region close to the anode. Calculation showed that the electric field decreases towards the anode, and then close to the anode it rises again. Contrary to the situation in argon, the present calculations showed that in nitrogen the electric field in the anode layer is always accelerating. However, the average electric field in the anode layer is weaker than in the adjacent arc column (the so-called negative anode layer voltage). The voltage drop in the Langmuir sheath is also negative. It is shown that the main difference in anode layer voltages between an arc in nitrogen and an arc in argon is due to the high reactive thermal conductivity in nitrogen.

  10. Process and electrolyte for applying barrier layer anodic coatings

    International Nuclear Information System (INIS)

    Various metals may be anodized, and preferably barrier anodized, by anodizing the metal in an electrolyte comprising quaternary ammonium compound having a complex metal anion in a solvent containing water and a polar, water soluble organic material. (U.S.)

  11. On the influence of interfacial properties to the bending rigidity of layered structures

    Science.gov (United States)

    Peng, Shenyou; Wei, Yujie

    2016-07-01

    Layered structures are ubiquitous, from one-atom thick layers in two-dimensional materials, to nanoscale lipid bi-layers, and to micro and millimeter thick layers in composites. The mechanical behavior of layered structures heavily depends on the interfacial properties and is of great interest in engineering practice. In this work, we give an analytical solution of the bending rigidity of bilayered structures as a function of the interfacial shear strength. Our results show that while the critical bending stiffness when the interface starts to slide plastically is proportional to the interfacial shear strength, there is a strong nonlinearity between the rigidity and the applied bending after interfacial plastic shearing. We further give semi-analytical solutions to the bending of bilayers when both interfacial shearing and pre-existing crack are present in the interface of rectangular and circular bilayers. The analytical solutions are validated by using finite element simulations. Our analysis suggests that interfacial shearing resistance, interfacial stiffness and preexisting cracks dramatically influence the bending rigidity of bilayers. The results can be utilized to understand the significant stiffness difference in typical biostructures and novel materials, and may also be used for non-destructive detection of interfacial crack in composites when stiffness can be probed through vibration techniques.

  12. Two-Dimensional Layered Oxide Structures Tailored by Self-Assembled Layer Stacking via Interfacial Strain.

    Science.gov (United States)

    Zhang, Wenrui; Li, Mingtao; Chen, Aiping; Li, Leigang; Zhu, Yuanyuan; Xia, Zhenhai; Lu, Ping; Boullay, Philippe; Wu, Lijun; Zhu, Yimei; MacManus-Driscoll, Judith L; Jia, Quanxi; Zhou, Honghui; Narayan, Jagdish; Zhang, Xinghang; Wang, Haiyan

    2016-07-01

    Study of layered complex oxides emerge as one of leading topics in fundamental materials science because of the strong interplay among intrinsic charge, spin, orbital, and lattice. As a fundamental basis of heteroepitaxial thin film growth, interfacial strain can be used to design materials that exhibit new phenomena beyond their conventional forms. Here, we report a strain-driven self-assembly of bismuth-based supercell (SC) with a two-dimensional (2D) layered structure. With combined experimental analysis and first-principles calculations, we investigated the full SC structure and elucidated the fundamental growth mechanism achieved by the strain-enabled self-assembled atomic layer stacking. The unique SC structure exhibits room-temperature ferroelectricity, enhanced magnetic responses, and a distinct optical bandgap from the conventional double perovskite structure. This study reveals the important role of interfacial strain modulation and atomic rearrangement in self-assembling a layered singe-phase multiferroic thin film, which opens up a promising avenue in the search for and design of novel 2D layered complex oxides with enormous promise. PMID:27295399

  13. On the influence of the external optical radiation upon anode double layers

    International Nuclear Information System (INIS)

    The obtained results demonstrate that the changes in the parameters (frequency, amplitude) of electrical oscillations generated in an anode double layer can be used as optical detectors when the anode glow is irradiated with an external optical electromagnetic wave. It has been demonstrated that the local electrical properties of an anode glow have changed under the influence of electromagnetic radiation

  14. Flexible organic light-emitting diodes with ITO/Ag/ITO multi-layers as anodes

    Institute of Scientific and Technical Information of China (English)

    LI Yang; WANG Liduo; CHANG Chun; DUAN Lian; QIU Yong

    2004-01-01

    The transparent ITO/Ag/ITO multi-layers are developed as anodes on flexible PET (poly(ethylene terephthalate)) substrates. The influence of these anodes on FOLED (Flexible Organic Light-emitting Diodes) is investigated. From the results of research, it can be seen that the multi-layer anode has optimum characteristics, whose sheet resistance is 11 Ω and optical transmittance is about 80%,when the thickness of Ag sandwiched by two ITO layers is in the range of 14-18 nm. It is demonstrated that the OLED devices with multi-layer anodes give better luminescence and higher efficiency compared with those with single ITO an odes.

  15. Numerical study of the anode boundary layer in atmospheric pressure arc discharges

    Science.gov (United States)

    Semenov, I. L.; Krivtsun, I. V.; Reisgen, U.

    2016-03-01

    The anode boundary layer in atmospheric pressure arc discharges is studied numerically on the basis of the hydrodynamic (diffusion) equations for plasma components. The governing equations are formulated in a unified manner without the assumptions of thermal equilibrium, ionization equilibrium or quasi-neutrality. For comparison, a quasi-neutral model of the anode layer is also considered. The numerical computations are performed for an argon arc at typical values of the current density in anode layers (500-2000 A cm-2). The results of numerical modelling show that the common collisionless model of the sheath fails to describe the sheath region for the problem under consideration. For this reason, a detailed analysis of the anode sheath is performed using the results of unified modelling. In addition, the distributions of plasma parameters in the anode layer are analysed and the basic characteristics of the layer (anode voltage drop, sheath voltage drop, anode layer thickness, sheath thickness, heat flux to the anode) are calculated. Our results are found to be in good agreement with the existing theoretical predictions and experimental data. The dependence of the anode layer characteristics on the current density is also discussed.

  16. Molecular dynamics simulations of the microstructure of the aluminum/alumina interfacial layer

    International Nuclear Information System (INIS)

    Highlights: • We obtained two energetically preferable aluminum/alumina interface systems by work of adhesion. • We predicted the presence of an interfacial layer in aluminum/alumina interface. • The interfacial layer has a thickness of ∼1 nm and is comprised of aluminum suboxide. • The interfacial layer inherits its structure from the moiety of alumina. - Abstract: The atomic structure and charge distribution pattern of the Al/α-Al2O3 interface were studied utilizing molecular dynamics simulations. In order to accurately describe the interactions between the atoms around the interface, the charge transfer ionic and embedded atom method potential was used. Energetically preferable Al/α-Al2O3 interface systems were first determined to study the layer structures of the interface systems. Two energetically preferable Al/α-Al2O3 interface systems with a [1¯10](111)Al∥[101¯0](0001)Al2O3 orientation relationship were obtained, corresponding to the atop-O Al-terminated and atop-O O-terminated relaxed models, respectively. Further studies revealed the presence of an interfacial layer, which is consistent with experimental results. The models predict a thickness of the interfacial layer between 12.14 Å and 16.82 Å. It is composed of aluminum suboxide (with an Al to O atomic ratio between 1:1.07 and 1:1.17). In addition, both the combination between the interfacial layer and the metallic Al layer and the interfacial layer and the ceramic α-Al2O3 were perfect. In order to further study the atomic structure of the Al/α-Al2O3 interfacial layer, it was isolated from the system and modeled separately. An analysis of the radial distribution function revealed that the interfacial layer inherits its structure from the α-Al2O3 moiety. The study of the charge distributions in the interface systems indicates that the charge of the Al atoms in the interfacial layer is mainly in the range from +2.1 e to +2.6 e while the charge of the O atoms is at the saturated

  17. The Silicon-To-Silicon Anodic Bonding Using Sputter Deposited Intermediate Glass Layer

    OpenAIRE

    TIWARI, R; Chandra, S.

    2011-01-01

    Glass-to-silicon anodic bonding is an attractive process for packaging of microelectronics devices and Micro-electro-mechanical Systems (MEMS). Silicon to silicon anodic bonding can also be accomplished by incorporating an intermediate glass layer. In the present work, silicon-to-silicon anodic bonding has been studied with an intermediate borosilicate glass layer deposited by RF magnetron sputtering process. The bonding was carried out at low dc voltage of about 48 V at 400 °C. Surface rough...

  18. Impact of anode catalyst layer porosity on the performance of a direct formic acid fuel cell

    International Nuclear Information System (INIS)

    Highlights: ► Lithium carbonate is used as a pore-former to increase porosity of anode catalyst layer. ► Maximum power density increased by 25%. ► Onset potential for formic acid electro-oxidation reduced by 30 mV for anode catalyst layer with 17.5 wt% pore-former. ► Electrochemical impedance spectra confirm increased formic acid concentration inside the anode catalyst layer pores. - Abstract: Direct formic acid fuel cells (DFAFCs) have attracted much attention in the last few years for portable electronic devices, due to their potential of being high efficiency power sources. They have the potential to replace the state-of-the-art batteries in cell phones, PDAs, and laptop computers if their power density and durability can be improved. In the present investigation, the influence of increased anode catalyst layer porosity on DFAFC power density performance is studied. Lithium carbonate (Li2CO3) was used as a pore-former in this study because of its facile and complete removal after catalyst layer fabrication. The anode catalyst layers presented herein contained unsupported Pt/Ru catalyst and Li2CO3 (in the range of 0–50 wt%) bound with proton conducting ionomer. Higher DFAFC performance is obtained because of the increased porosity within the anode catalyst layer through enhanced reactant and product mass transport. The maximum power density of DFAFC increased by 25% when pore-former was added to the anode catalyst ink. The formic acid onset potential for the anode catalyst layer with 17.5 wt% pore-former was reduced by 30 mV. A constant phase element based equivalent-circuit model was used to investigate anode impedance spectra. Fitted values for the anode impedance spectra confirm the improvement in performance due to an increase in formic acid concentration inside the anode catalyst layer pores along with efficient transport of reactants and products.

  19. Dithiapyrannylidenes as efficient hole collection interfacial layers in organic solar cells.

    Science.gov (United States)

    Berny, Stéphane; Tortech, Ludovic; Véber, Michelle; Fichou, Denis

    2010-11-01

    One inherent limitation to the efficiency of photovoltaic solar cells based on polymer/fullerene bulk heterojunctions (BHJs) is the accumulation of positive charges at the anodic interface. The unsymmetrical charge collection of holes and electrons dramatically decreases the short-circuit current. Interfacial layers (IFLs) such as poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) have no effect on the unbalanced electron/hole transport across the BHJ. We report here on the use of dithiapyrannylidenes (DITPY), a new class of planar quinoid compounds, as efficient hole-transporting/electron-blocking layers in organic solar cells based on poly(3-hexylthiophene)/[6,6]-phenyl-C(61)-butyric acid methyl ester (P3HT:PCBM) BHJs. Inserting a 15-nm-thick IFL of 4,4'-bis(diphenyl-2,6-thiapyrannylidene) (DITPY-Ph(4)) between the indium-tin oxide electrode and the P3HT:PCBM BHJ prevents detrimental space-charge effects and favors recombination-limited currents. Current-sensing atomic force microscopy reveals a drastic increase of the hole-carrying pathways in DITPY-Ph(4) compared to PEDOT:PSS. In ambient conditions, photovoltaic cells using DITPY-Ph(4) exhibit an 8% increase in the current density, although the conversion efficiency remains slightly lower compared to PEDOT:PSS-based devices. Finally, we present a detailed analysis of the photocurrent generation, showing that DITPY-Ph(4) IFLs induce a transition from unproductive space-charge-limited currents to recombination-limited currents. PMID:21028838

  20. Interfacial Characteristics of Efficient Bulk Heterojunction Solar Cells Fabricated on MoOx Anode Interlayers.

    Science.gov (United States)

    Jasieniak, Jacek J; Treat, Neil D; McNeill, Christopher R; de Villers, Bertrand J Tremolet; Della Gaspera, Enrico; Chabinyc, Michael L

    2016-05-01

    The role of the interface between an MoOx anode interlayer and a polymer:fullerene bulk heterojunction is investigated. Processing differences in the MoOx induce large variations in the vertical stratification of the bulk heterojunction films. These variations are found to be inconsistent in predicting device performance, with a much better gauge being the quantity of polymer chemisorbed to the anode interlayer. PMID:26468898

  1. Interfacial Characteristics of Efficient Bulk Heterojunction Solar Cells Fabricated on MoOx Anode Interlayers

    Energy Technology Data Exchange (ETDEWEB)

    Jasieniak, Jacek J.; Treat, Neil D.; McNeill, Christopher R.; Tremolet de Villers, Bertrand J.; Gaspera, Enrico Della; Chabinyc, Michael L.

    2016-05-25

    The role of the interface between an MoOx anode interlayer and a polymer:fullerene bulk heterojunction is investigated. Processing differences in the MoOx induce large variations in the vertical stratification of the bulk heterojunction films. These variations are found to be inconsistent in predicting device performance, with a much better gauge being the quantity of polymer chemisorbed to the anode interlayer.

  2. Probing nonlinear rheology layer-by-layer in interfacial hydration water.

    Science.gov (United States)

    Kim, Bongsu; Kwon, Soyoung; Lee, Manhee; Kim, Q Hwan; An, Sangmin; Jhe, Wonho

    2015-12-22

    Viscoelastic fluids exhibit rheological nonlinearity at a high shear rate. Although typical nonlinear effects, shear thinning and shear thickening, have been usually understood by variation of intrinsic quantities such as viscosity, one still requires a better understanding of the microscopic origins, currently under debate, especially on the shear-thickening mechanism. We present accurate measurements of shear stress in the bound hydration water layer using noncontact dynamic force microscopy. We find shear thickening occurs above ∼ 10(6) s(-1) shear rate beyond 0.3-nm layer thickness, which is attributed to the nonviscous, elasticity-associated fluidic instability via fluctuation correlation. Such a nonlinear fluidic transition is observed due to the long relaxation time (∼ 10(-6) s) of water available in the nanoconfined hydration layer, which indicates the onset of elastic turbulence at nanoscale, elucidating the interplay between relaxation and shear motion, which also indicates the onset of elastic turbulence at nanoscale above a universal shear velocity of ∼ 1 mm/s. This extensive layer-by-layer control paves the way for fundamental studies of nonlinear nanorheology and nanoscale hydrodynamics, as well as provides novel insights on viscoelastic dynamics of interfacial water. PMID:26644571

  3. UV-Ozone Treatment on Cs2CO3 Interfacial Layer for the Improvement of Inverted Polymer Solar Cells

    OpenAIRE

    Yusheng Xin; Zixuan Wang; Lu Xu; Xiaowei Xu; Yang Liu; Fujun Zhang

    2013-01-01

    Inverted configuration polymer solar cells (IPSCs) were prepared by using Cs2CO3 modified indium tin oxide (ITO) substrates as cathode and MoO3/Al as anode, ITO/Cs2CO3/P3HT:PCBM/MoO3/Al. The interfacial Cs2CO3 layers were conducted with annealing treatment and different time UV-Ozone treatment. The power conversion efficiency (PCE) of IPSCs was improved to 1% when the UV-Ozone treatment time is 15 minutes, with the open-circuit voltage of 0.48 V, short-circuit current density of 5.4 mA/cm2, a...

  4. Polyfluorene Electrolytes Interfacial Layer for Efficient Polymer Solar Cells: Controllably Interfacial Dipoles by Regulation of Polar Groups.

    Science.gov (United States)

    Liu, Huimin; Hu, Lin; Wu, Feiyan; Chen, Lie; Chen, Yiwang

    2016-04-20

    The polar groups in the conjugated polyelectrolytes (CPEs) can create the favorable dipoles at the electrode/active layer interface, which is critical for the CPEs to minimize the interfacial energy barrier in polymer solar cells (PSCs). Herein, a series of CPEs based on poly [(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-co-2,7-(9,9-dioctylfluorene)] derivates (PFNs) (PFN30, PFN50, PFN70, and PFN100) with different mole ratio of polar groups (-N(C2H5)2) were designed and synthesized to investigate the effect of the numbers of polar groups on the interfacial dipoles. Controllably interfacial dipoles could be readily achieved by only tuning the numbers of -N(C2H5)2 in PFNs, as revealed by the work function of the PFNs modified ITO gradually reduced as the loadings of the -N(C2H5)2 increased. In addition, increasing the numbers of -N(C2H5)2 in PFNs were also favorable for developing the smooth and homogeneous morphology of the active layer. As a result, the content of the polar amine in the PFNs exerted great influence on the performance of polymer solar cells. Increasing the numbers of the pendent -N(C2H5)2 could effectively improve the power conversion efficiency (PCE) of the devices. Among these PFNs, PFN100 with the highest content of -N(C2H5)2 polar groups delivered the device with the best PCE of 3.27%. It indicates tailoring the content of the polar groups in the CPEs interlayer is a facial and promising approach for interfacial engineering to developing high performance PSCs. PMID:27028166

  5. Formation of Interfacial Carbide Layers in Multilayer Ti/DLC Thin Films

    Science.gov (United States)

    Scaramazza, Jasen; Buck, Zachary; Donato, Tyler; Curran, Brittany; Lunk, C. A.; Lofland, S. E.; Hettinger, J. D.

    2012-02-01

    Titanium (Ti)/Diamond-like-carbon (DLC) and Chromium (Cr)/Carbon (C) multilayer films were prepared on c-axis oriented single crystal sapphire (Al2O3) substrates using magnetron sputtering. Interfacial properties of the films were analyzed using x-ray reflectivity and scanning electron microscopy. When DLC is sputtered on a layer of Ti, an interfacial layer of titanium carbide (TiC) forms which is reported for the first time. Energy provided by the substrate bias necessary to facilitate DLC sp3 bond formation is suspected of allowing TiC to synthesize in a thin layer before DLC forms. It was also found that DLC has difficulty forming on Cr. These results are relevant to biomedical applications where DLC is applied as a low friction/wear film that can be formed on the surface of implants composed mainly of titanium. Further investigation into the medical and tribological effects of TiC interfacial layers is suggested.

  6. The effect of interfacial layers on charge transport in organic solar cell

    Science.gov (United States)

    Mbuyise, Xolani G.; Tonui, Patrick; Mola, Genene Tessema

    2016-09-01

    The effect of interfacial buffer layers in organic photovoltaic cell (OPV) whose active layer is composed of poly(3 hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend was studied. The electrical properties of OPV devices produced with and without interfacial layers are compared and discussed in terms of measured parameters of the cells. The charge transport properties showed significant difference on the mobility and activation factor between the two types of device structures. The life time measurements in the unprotected conditions are also presented and discussed.

  7. Simple O2 Plasma-Processed V2O5 as an Anode Buffer Layer for High-Performance Polymer Solar Cells

    DEFF Research Database (Denmark)

    Bao, Xichang; Zhu, Qianqian; Wang, Ting;

    2015-01-01

    A simple O2 plasma processing method for preparation of a vanadium oxide (V2O5) anode buffer layer on indium tin oxide (ITO)-coated glass for polymer solar cells (PSCs) is reported. The V2O5 layer with high transmittance and good electrical and interfacial properties was prepared by spin coating a...... vanadium(V) triisopropoxide oxide alcohol solution on ITO and then O2 plasma treatment for 10 min [V2O5 (O2 plasma)]. PSCs based on P3HT:PC61BM and PBDTTT-C:PC71BM using V2O5 (O2 plasma) as an anode buffer layer show high power conversion efficiencies (PCEs) of 4.47 and 7.54%, respectively, under the...... plasma) anode buffer layer. The improved PCE is ascribed to the greatly improved fill factor and enhanced short-circuit current density of the devices, which benefited from the change in the work function of V2O5, a surface with many dangling bonds for better interfacial contact, and the excellent charge...

  8. An identification algorithm of model kinetic parameters of the interfacial layer growth in fiber composites

    Science.gov (United States)

    Zubov, V.; Lurie, S.; Solyaev, Y.

    2016-04-01

    This paper considers the identification algorithm of parameters included in a parabolic law that is often used to predict the time dependence of the thickness of the interfacial layers in the structure of composite materials based on a metal matrix. The incubation period of the process and the speed of reaction and pressure are taken into account. The proposed algorithm of identification is based on the introduction of a minimized objective function of a special kind. The problem of identification of unknown parameters in the parabolic law is formulated in a variational form. The authors of the paper have determined the desired parameters, under which the objective function has a minimum value. It is shown that on the basis of four known experimental values of the interfacial layer thickness, corresponding to different values of temperature, pressure and the time of the interfacial layer growth, it is possible to identified four model parameters. They are the activation energy, a pre-exponential parameter, the delay time of the start of the interfacial layer formation, and the parameter determining the pressure effect on the rate of interfacial layer growth. The stability of the proposed identification algorithm is also studied.

  9. Effects of Complex Structured Anodic Oxide Dielectric Layer Grown in Pore Matrix for Aluminum Capacitor.

    Science.gov (United States)

    Shin, Jin-Ha; Yun, Sook Young; Lee, Chang Hyoung; Park, Hwa-Sun; Suh, Su-Jeong

    2015-11-01

    Anodization of aluminum is generally divided up into two types of anodic aluminum oxide structures depending on electrolyte type. In this study, an anodization process was carried out in two steps to obtain high dielectric strength and break down voltage. In the first step, evaporated high purity Al on Si wafer was anodized in oxalic acidic aqueous solution at various times at a constant temperature of 5 degrees C. In the second step, citric acidic aqueous solution was used to obtain a thickly grown sub-barrier layer. During the second anodization process, the anodizing potential of various ranges was applied at room temperature. An increased thickness of the sub-barrier layer in the porous matrix was obtained according to the increment of the applied anodizing potential. The microstructures and the growth of the sub-barrier layer were then observed with an increasing anodizing potential of 40 to 300 V by using a scanning electron microscope (SEM). An impedance analyzer was used to observe the change of electrical properties, including the capacitance, dissipation factor, impedance, and equivalent series resistance (ESR) depending on the thickness increase of the sub-barrier layer. In addition, the breakdown voltage was measured. The results revealed that dielectric strength was improved with the increase of sub-barrier layer thickness. PMID:26726615

  10. Formation of Nanoporous Tin Oxide Layers on Different Substrates during Anodic Oxidation in Oxalic Acid Electrolyte

    Directory of Open Access Journals (Sweden)

    Leszek Zaraska

    2015-01-01

    Full Text Available Nanoporous tin oxide layers were obtained on various Sn substrates including high- and low-purity foils and wire by one-step anodic oxidation carried out in a 0.3 M oxalic acid electrolyte at various anodizing potentials. In general, amorphous oxide layers with the atomic ratio of Sn : O (1 : 1 were grown during anodization, and a typical structure of the as-obtained film consists of the “outer” layer with less regular, interconnetted pores and the “inner” layer with much more uniform and regular channels formed as a result of vigorous gas evolution. It was found that the use of electrochemical cell with the sample placed horizontally on the metallic support and stabilized by the Teflon cover, instead of the typical two-electrode system with vertically arranged electrodes, can affect the morphology of as-obtained layers and allows fabrication of nanoporous oxides even at anodizing potentials up to 11 V. An average pore diameter in the “outer” oxide layer increases with increasing anodizing potential, and no significant effect of substrate purity on the structure of anodic film was proved, except better uniformity of the oxides grown on high-purity Sn. A strong linear relationship between the average steady-state current density and anodizing potential was also observed.

  11. Studies of Interfacial Layer and Its Effect on Magnetic Properties of Glass-Coated Microwires

    Science.gov (United States)

    Zhukov, Arcady; Shuvaeva, Evgenia; Kaloshkin, Sergei; Churyukanova, Margarita; Kostitsyna, Elena; Zhdanova, Margarita; Talaat, Ahmed; Ipatov, Mihail; Zhukova, Valentina

    2016-05-01

    We present studies of the interfacial layer between the metallic nucleus and glass coating in ferromagnetic Fe- and Co-rich microwires. Using a scanning electron microscope, we obtained the image of the interfacial layer and the elements distribution within the glass coating and metallic nucleus. This allowed us to estimate the thickness of the interfacial layer ( t il). For both Fe- and Co-rich microwires, t il ≈ 0.5 μm. We measured the frequency dependence of the giant magnetoimpedance ratio in Fe and Co-rich microwires, estimated the minimum penetration depth, and discussed the optimum frequency for different microwires considering the difference of the magnetic structure and the magnetic anisotropy inside the microwire and near the surface.

  12. Self-healing sandwich structures incorporating an interfacial layer with vascular network

    International Nuclear Information System (INIS)

    A self-healing capability specifically targeted for sandwich composite laminates based on interfacial layers with built-in vascular networks is presented. The self-healing occurs at the facesheet–core interface through an additional interfacial layer to seal facesheet cracks and rebond facesheet–core regions. The efficacy of introducing the self-healing system at the facesheet–core interface is evaluated through four-point bend and edgewise compression testing of representative foam core sandwich composite specimens with impact induced damage. The self-healing interfacial layer partially restored the specific initial stiffness, doubling the residual initial stiffness as compared to the control specimen after the impact event. The restoration of the ultimate specific skin strength was less successful. The results also highlight the critical challenge in self-healing of sandwich composites, which is to rebond facesheets which have separated from the core material. (paper)

  13. Investigation of top-emitting OLEDs using molybdenum oxide as anode buffer layer

    Institute of Scientific and Technical Information of China (English)

    LIN Hui; YU Jun-sheng; ZHANG Wei

    2012-01-01

    A high-effective bottom anode is essential for high-performance top-emitting organic light-emitting devices (OLEDs).In this paper,Ag-based top-emitting OLEDs are investigated.Ag has the highest reflectivity for visible light among all metals,yet its hole-injection properties are not ideal for anodes of top-emitting OLED.The performance of the devices is significantly improved using the molybdenum oxide as anode buffer layer at the surface of Ag.By introducing the molybdenum oxide,the hole injection from Ag anodes into top-emitting OLED is largely enhanced with rather high reflectivity retained.

  14. UV-Ozone Treatment on Cs2CO3 Interfacial Layer for the Improvement of Inverted Polymer Solar Cells

    International Nuclear Information System (INIS)

    Inverted configuration polymer solar cells (IPSCs) were prepared by using Cs2CO3 modified indium tin oxide (ITO) substrates as cathode and MoO3/Al as anode, ITO/Cs2CO3/P3HT:PCBM/MoO3/Al. The interfacial Cs2CO3 layers were conducted with annealing treatment and different time UV-Ozone treatment. The power conversion efficiency (PCE) of IPSCs was improved to 1% when the UV-Ozone treatment time is 15 minutes, with the open-circuit voltage of 0.48 V, short-circuit current density of 5.4 mA/cm2, and fill factor of 39%. The improvement of IPSCs should be attributed to the increased electron transporting and collection ability of Cs2CO3 layer induced by UV-Ozone treatment. The underlying mechanism of PCE improvement was discussed in terms of series and shunt resistance of cells induced by UV-Ozone treatment on Cs2CO3 layer, and the mole ratio of Cs to O of Cs2CO3 layer with different UV-Ozone treatment was investigated by scanning electron microscopy operating in the mode for in situ energy dispersive X-ray (EDX) spectra.

  15. Electrode dependent interfacial layer variation in metal-oxide-semiconductor capacitor

    International Nuclear Information System (INIS)

    The interfacial layer between oxide and semiconductor in metal-oxide-semiconductor (MOS) capacitors depends on the metal electrode material. The metal/HfO2/Si and metal/HfO2/Ge capacitor were made using an atomic layer deposited HfO2 dielectric films and Mo, Ru, and Pt electrodes above Si substrate and Ti, Ru, and Pt electrodes above Ge substrate. The measured saturation capacitance was varied with electrode and evaluated to capacitance equivalent thickness (CET). In Si-based MOS capacitor, the CET value of the capacitor with Pt electrode is larger than those with Mo and Ru electrode. In addition, the CET is 27.4 A, 38.2 A, and 30.8 A for Ti, Ru, and Pt electrode, respectively, for Ge-based MOS capacitors. The CET variation with electrode is attributed the variation of dielectric constant of HfO2 dielectric and the difference of interfacial layer. The CET variation is well in agreement with the interfacial layer thickness taken by a transmission electron microscopy. The thickness variation of interfacial layer results from the oxygen gettering ability of the electrode even though they are apart

  16. Adhesion enhancement of hard coatings deposited on flexible plastic substrates using an interfacial buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Day-Shan; Wu, Cheng-Yang, E-mail: dsliu@sunws.nfu.edu.t [Institute of Electro-Optical and Materials Science, National Formosa University, Huwei, Taiwan 63201 (China)

    2010-05-05

    An interfacial buffer layer has been developed to improve the silicon oxide (SiO{sub x}) hard coating adhered to a flexible plastic substrate through a consecutive plasma-enhanced chemical vapour deposition process, using the same organosilicon precursor. The adhesion of the hard coating structure, correlated with the buffer layer thickness, was rated by the standard tape-peeling test. An excellent adhesion (rank 5B) was available for the hard coating structure with an interfacial buffer layer deposited on polycarbonate and polymethylmethacrylate substrates. The degree of adhesion strength for the hard coating structures was measured by the standard scratch test. The increase in the critical loads determined from the scratch test was well correlated with the tape-peeling test results. The hard coating structure showed excellent adhesion and also corresponded to a minimum residual stress. The mechanisms responsible for the adhesion enhancement were linked to the specific chemical bonds of the hydrocarbon C-H bond, and cross-linking Si-C bond appeared in the interfacial buffer layer. The C-H bond was recognized as a hydrophobic group that was favourable for minimizing the adsorption of ambient contaminants potentially arising during deposition, while the cross-linking Si-C bond functioned to compensate the large tensile stress residing in the SiO{sub x} hard coating. As a consequence, a close contact and progressive morphology resulting in excellent adhesion were observed at the interface of the hard coating structure with an interfacial buffer layer.

  17. Improvement of the interfacial Dzyaloshinskii-Moriya interaction by introducing a Ta buffer layer

    International Nuclear Information System (INIS)

    We report systematic measurements of the interfacial Dzyaloshinskii-Moriya interaction (iDMI) by employing Brillouin light scattering in Pt/Co/AlOx and Ta/Pt/Co/AlOx structures. By introducing a tantalum buffer layer, the saturation magnetization and the interfacial perpendicular magnetic anisotropy are significantly improved due to the better interface between heavy metal and ferromagnetic layer. From the frequency shift between Stokes- and anti-Stokes spin-waves, we successively obtain considerably larger iDM energy densities (Dmax = 1.65 ± 0.13 mJ/m2 at tCo = 1.35 nm) upon adding the Ta buffer layer, despite the nominally identical interface materials. Moreover, the energy density shows an inverse proportionality with the Co layer thickness, which is the critical clue that the observed iDMI is indeed originating from the interface between the Pt and Co layers

  18. Interfacial electron transfer and bioelectrocatalysis of carbonized plant material as effective anode of microbial fuel cell

    International Nuclear Information System (INIS)

    ABSTRACT: Effective use of natural materials to fabricate porous carbonaceous structures for anodes of microbial fuel cells (MFCs) has a high potential for substantial cost reduction in MFC. In this study, three kinds of plant materials, i.e. king mushroom, wild mushroom and corn stem, were investigated for fabrication of conductive electrode materials by simple carbonization procedures. Structure–reactivity relationships of these electrodes were systematically studied with electrochemical redox probe ([Fe(CN)6]3−/4−) and biofilm electroactivity. The electrochemical and bioelectrochemical accessibilities of the carbonized electrodes were evaluated by impedance, cyclic voltammetry and chronoamperometry techniques in order to study the electron transfer rate (Kapp), charge transfer resistances, oxidative current density and bioelectroactive moieties. The results showed that the electron transfer resistance (Rct) was 94 Ω for carbonized corn stem electrode with an electron transfer rate (Kapp) of 3.44 × 10−2 cm s−1 for Fe2+/Fe3+ redox probe. Higher bioelectroactivity (9.29 × 10−8 mol cm−2) was found from biofilm on carbonized corn stem (Rbiofilm, 45 Ω) with an electron transfer rate (bacteria-anode) of 63 × 10−5 cm s−1. The maximum bioelectrocatalytic current (imax) of 3.12 mA cm−2 was obtained on carbon electrode derived from corn stem. That is 8 times higher than plain graphite electrode. The porous architecture, high electron transfer rate and high electroactive biofilm growth are attributes that qualify natural-material carbon anodes as low-cost alternative for MFC

  19. The thin-layer effect and interfacial stability in a two-layer Couette flow with similar liquids

    OpenAIRE

    Renardy, Y

    1987-01-01

    The linear stability of Couette flow composed of two layers of immiscible fluids, one lying on top of the other, is considered for the special case when the two fluids have similar mechanical properties. The interfacial eigenvalue is found in closed form by considering the two‐fluid problem as a perturbation of the one‐fluid problem. The importance of the role played by the viscosity difference, when one of the fluids is in a thin layer, is illustrated.

  20. Interfacial Atomic Structure of Twisted Few-Layer Graphene

    OpenAIRE

    Ryo Ishikawa; Nathan R. Lugg; Kazutoshi Inoue; Hidetaka Sawada; Takashi Taniguchi; Naoya Shibata; Yuichi Ikuhara

    2016-01-01

    A twist in bi- or few-layer graphene breaks the local symmetry, introducing a number of intriguing physical properties such as opening new bandgaps. Therefore, determining the twisted atomic structure is critical to understanding and controlling the functional properties of graphene. Combining low-angle annular dark-field electron microscopy with image simulations, we directly determine the atomic structure of twisted few-layer graphene in terms of a moiré superstructure which is parameterize...

  1. GaAs interfacial self-cleaning by atomic layer deposition

    Science.gov (United States)

    Hinkle, C. L.; Sonnet, A. M.; Vogel, E. M.; McDonnell, S.; Hughes, G. J.; Milojevic, M.; Lee, B.; Aguirre-Tostado, F. S.; Choi, K. J.; Kim, H. C.; Kim, J.; Wallace, R. M.

    2008-02-01

    The reduction and removal of surface oxides from GaAs substrates by atomic layer deposition (ALD) of Al2O3 and HfO2 are studied using in situ monochromatic x-ray photoelectron spectroscopy. Using the combination of in situ deposition and analysis techniques, the interfacial "self-cleaning" is shown to be oxidation state dependent as well as metal organic precursor dependent. Thermodynamics, charge balance, and oxygen coordination drive the removal of certain species of surface oxides while allowing others to remain. These factors suggest proper selection of surface treatments and ALD precursors can result in selective interfacial bonding arrangements.

  2. Solution-processed cathode interfacial layer materials for high-efficiency polymer solar cells

    Directory of Open Access Journals (Sweden)

    Biao Xiao

    2015-09-01

    Full Text Available Polymer solar cells (PSCs are a new type of renewable energy source currently being extensively investigated due to perceived advantages; such as being lightweight, low-cost and because of the unlimited materials resource. The power conversion efficiency of state-of-the-art PSCs has increased dramatically in the past few years, obtained mainly through the development of new electron donor polymers, acceptors, and novel device structures through the use of various electrode interfacial materials. In this short review, recent progress in solution-processed cathode interfacial layers that could significantly improve device performances is summarized and highlighted.

  3. Interface engineering of layer-by-Layer stacked graphene anodes for high-performance organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu; Tong, Shi Wun; Loh, Kian Ping [Department of Chemistry, National University of Singapore (Singapore); Xu, Xiang Fan; Oezyilmaz, Barbaros [Department of Physics, National University of Singapore (Singapore)

    2011-04-05

    An interface engineering process to deploy graphene film as the anode in poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl C61 butyric acid methyl ester (P3HT:PCBM)-based polymer solar cells is demonstrated. By modifying the interface between the graphene anode and the photoactive layer with MoO{sub 3} and poly(3,4-ethylenedioythiophene):poly(styrenesulfonate) (PEDOT:PSS), the power conversion efficiency of the solar cells reaches {approx}83.3% of control devices that use an indium tin oxide (ITO) anode. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Nanoscopic characterization of the water vapor-salt interfacial layer reveals a unique biphasic adsorption process.

    Science.gov (United States)

    Yang, Liu; He, Jianfeng; Shen, Yi; Li, Xiaowei; Sun, Jielin; Czajkowsky, Daniel M; Shao, Zhifeng

    2016-01-01

    Our quantitative understanding of water adsorption onto salt surfaces under ambient conditions is presently quite poor owing to the difficulties in directly characterizing this interfacial layer under these conditions. Here we determine the thickness of the interfacial layer on NaCl at different relative humidities (RH) based on a novel application of atomic force spectroscopy and capillary condensation theory. In particular, we take advantage of the microsecond-timescale of the capillary condensation process to directly resolve the magnitude of its contribution in the tip-sample interaction, from which the interfacial water thickness is determined. Further, to correlate this thickness with salt dissolution, we also measure surface conductance under similar conditions. We find that below 30% RH, there is essentially only the deposition of water molecules onto this surface, typical of conventional adsorption onto solid surfaces. However, above 30% RH, adsorption is simultaneous with the dissolution of ions, unlike conventional adsorption, leading to a rapid increase of surface conductance. Thus, water adsorption on NaCl is an unconventional biphasic process in which the interfacial layer not only exhibits quantitative differences in thickness but also qualitative differences in composition. PMID:27527905

  5. Interfacial Atomic Structure of Twisted Few-Layer Graphene

    Science.gov (United States)

    Ishikawa, Ryo; Lugg, Nathan R.; Inoue, Kazutoshi; Sawada, Hidetaka; Taniguchi, Takashi; Shibata, Naoya; Ikuhara, Yuichi

    2016-01-01

    A twist in bi- or few-layer graphene breaks the local symmetry, introducing a number of intriguing physical properties such as opening new bandgaps. Therefore, determining the twisted atomic structure is critical to understanding and controlling the functional properties of graphene. Combining low-angle annular dark-field electron microscopy with image simulations, we directly determine the atomic structure of twisted few-layer graphene in terms of a moiré superstructure which is parameterized by a single twist angle and lattice constant. This method is shown to be a powerful tool for accurately determining the atomic structure of two-dimensional materials such as graphene, even in the presence of experimental errors. Using coincidence-site-lattice and displacement-shift-complete theories, we show that the in-plane translation state between layers is not a significant structure parameter, explaining why the present method is adequate not only for bilayer graphene but also a few-layered twisted graphene. PMID:26888259

  6. Simple solution-processed CuOX as anode buffer layer for efficient organic solar cells

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Simple solution-processed CuOX hole transport layer for efficient organic solar cell. • Good photovoltaic performances as hole transport layer in OSCs with P3HT and PBDTTT-C as donor materials. • The device with CuOX as hole transport layer shows great improved stability compared with that of device with PEDOT:PSS as hole transport layer. - Abstract: A simple, solution-processed ultrathin CuOX anode buffer layer was fabricated for high performance organic solar cells (OSCs). XPS measurement demonstrated that the CuOX was the composite of CuO and Cu2O. The CuOX modified ITO glass exhibit a better surface contact with the active layer. The photovoltaic performance of the devices with CuOX layer was optimized by varying the thickness of CuOX films through changing solution concentration. With P3HT:PC61BM as the active layer, we demonstrated an enhanced PCE of 4.14% with CuOX anode buffer layer, compared with that of PEDOT:PSS layer. The CuOX layer also exhibits efficient photovoltaic performance in devices with PBDTTT-C:PC71BM as the active layer. The long-term stability of CuOX device is better than that of PEDOT:PSS device. The results indicate that the easy solution-processed CuOX film can act as an efficient anode buffer layer for high-efficiency OSCs

  7. Study on the interfacial layer in ZnO/GaN heterostructure light-emitting diode

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Seung-Ho; Chung, Tae-Hoon [Department of Materials Science and Engineering, Photonic and Electronic Thin Film Laboratory, Chonnam National University, 300 Yong-bong dong, Gwangju 500-757 (Korea, Republic of); Lee, Byung-Teak [Department of Materials Science and Engineering, Photonic and Electronic Thin Film Laboratory, Chonnam National University, 300 Yong-bong dong, Gwangju 500-757 (Korea, Republic of)], E-mail: btlee@jnu.ac.kr

    2009-02-15

    Heterostructure light-emitting diodes (LEDs) were fabricated by growing Ga-doped n-ZnO and undoped ZnO layers on p-GaN/Al{sub 2}O{sub 3} templates. The p-n junction showed a diode like I-V characteristic and emitted electroluminescence (EL) peaks at 430 nm, 440 nm and 480 nm along with a broad band of yellow light. An interfacial layer was observed between ZnO and GaN, identified as ZnGa{sub 2}O{sub 4} by transmission electron microscopy and X-ray diffraction analysis. It was observed that thickness of the interfacial layer did not significantly affect EL characteristics of the ZnO/GaN heterostructure LED.

  8. Study on the interfacial layer in ZnO/GaN heterostructure light-emitting diode

    International Nuclear Information System (INIS)

    Heterostructure light-emitting diodes (LEDs) were fabricated by growing Ga-doped n-ZnO and undoped ZnO layers on p-GaN/Al2O3 templates. The p-n junction showed a diode like I-V characteristic and emitted electroluminescence (EL) peaks at 430 nm, 440 nm and 480 nm along with a broad band of yellow light. An interfacial layer was observed between ZnO and GaN, identified as ZnGa2O4 by transmission electron microscopy and X-ray diffraction analysis. It was observed that thickness of the interfacial layer did not significantly affect EL characteristics of the ZnO/GaN heterostructure LED

  9. The simulation of the temperature effects on the microhardness of anodic alumina oxide layers

    Directory of Open Access Journals (Sweden)

    M. Gombár

    2014-01-01

    Full Text Available In order to improve the mechanical properties of the layer deposited by anodic oxidation of aluminum on the material EN AW-1050 H24, in the contribution was investigated the microhardness of the deposited layer as a function of the physic-chemical factors affecting in the process of anodic oxidation at the constant anodic current density J = 3 A.dm-2 in electrolyte formed by sulfuric acid and oxalic acid, with the emphasis on the influence of electrolyte temperature in the range – 1,78 °C to 45,78 °C. The model of the studied dependence was compiled based on mathematical and statistical analysis of matrix from experimental obtained data from composite rotation plan of experiment with five independent variable factors (amount of sulfuric acid in the electrolyte, the amount of oxalic acid in the electrolyte, electrolyte, anodizing time and applied voltage.

  10. Nanoengineering and interfacial engineering of photovoltaics by atomic layer deposition

    Science.gov (United States)

    Bakke, Jonathan R.; Pickrahn, Katie L.; Brennan, Thomas P.; Bent, Stacey F.

    2011-09-01

    Investment into photovoltaic (PV) research has accelerated over the past decade as concerns over energy security and carbon emissions have increased. The types of PV technology in which the research community is actively engaged are expanding as well. This review focuses on the burgeoning field of atomic layer deposition (ALD) for photovoltaics. ALD is a self-limiting thin film deposition technique that has demonstrated usefulness in virtually every sector of PV technology including silicon, thin film, tandem, organic, dye-sensitized, and next generation solar cells. Further, the specific applications are not limited. ALD films have been deposited on planar and nanostructured substrates and on inorganic and organic devices, and vary in thickness from a couple of angstroms to over 100 nm. The uses encompass absorber materials, buffer layers, passivating films, anti-recombination shells, and electrode modifiers. Within the last few years, the interest in ALD as a PV manufacturing technique has increased and the functions of ALD have expanded. ALD applications have yielded fundamental understanding of how devices operate and have led to increased efficiencies or to unique architectures for some technologies. This review also highlights new developments in high throughput ALD, which is necessary for commercialization. As the demands placed on materials for the next generation of PV become increasingly stringent, ALD will evolve into an even more important method for research and fabrication of solar cell devices.

  11. Thermodynamics, interfacial pressure isotherms and dilational rheology of mixed protein-surfactant adsorption layers.

    Science.gov (United States)

    Fainerman, V B; Aksenenko, E V; Krägel, J; Miller, R

    2016-07-01

    Proteins and their mixtures with surfactants are widely used in many applications. The knowledge of their solution bulk behavior and its impact on the properties of interfacial layers made great progress in the recent years. Different mechanisms apply to the formation process of protein/surfactant complexes for ionic and non-ionic surfactants, which are governed mainly by electrostatic and hydrophobic interactions. The surface activity of these complexes is often remarkably different from that of the individual protein and has to be considered in respective theoretical models. At very low protein concentration, small amounts of added surfactants can change the surface activity of proteins remarkably, even though no strongly interfacial active complexes are observed. Also small added amounts of non-ionic surfactants change the surface activity of proteins in the range of small bulk concentrations or surface coverages. The modeling of the equilibrium adsorption behavior of proteins and their mixtures with surfactants has reached a rather high level. These models are suitable also to describe the high frequency limits of the dilational viscoelasticity of the interfacial layers. Depending on the nature of the protein/surfactant interactions and the changes in the interfacial layer composition rather complex dilational viscoelasticities can be observed and described by the available models. The differences in the interfacial behavior, often observed in literature for studies using different experimental methods, are at least partially explained by a depletion of proteins, surfactants and their complexes in the range of low concentrations. A correction of these depletion effects typically provides good agreement between the data obtained with different methods, such as drop and bubble profile tensiometry. PMID:26198014

  12. Interfacial properties of germanium nitride dielectric layers in germanium

    Science.gov (United States)

    Meiners, L. G.

    The first year's effort on this project has been primarily devoted to the design and construction of a low-pressure chemical vapor deposition system for growth of the germanium nitride layers. The gas manifold layout is shown schematically, as is the reactor assembly, and the vacuum pumping assembly. The generator-cavity system is capable of delivering 0-600 W of microwave power at 2.45 GHz. The power generating section has been constructed from components contained in a portable home microwave oven and the cavity was assembled from easily machinable pieces. The cw magnetron source was mounted directly on a cylindrical microwave cavity. The plasma was contained in an on-axis 20-mm o.d. quartz tube. Design tradeoffs and operating information are discussed.

  13. Enhancement of device performance of organic solar cells by an interfacial perylene derivative layer

    KAUST Repository

    Kim, Inho

    2010-05-26

    We report that device performance of organic solar cells consisting of zinc phthalocyanine and fullerene (C60) can be enhanced by insertion of a perylene derivative interfacial layer between fullerene and bathocuproine (BCP) exciton blocking layer (EBL). The morphology of the BCP is influenced by the underlying N,N′-dihexyl-perylene-3,4,9,10-bis(dicarboximide) (PTCDI-C6), which promotes migration of the cathode metal into the BCP layer. Insertion of a PTCDI-C6 layer between fullerene and BCP layers enhances the power conversion efficiency to 2.5%, an improvement of 32% over devices without PTCDI-C6 layer. The enhancement in device performance by insertion of PTCDI-C6 is attributed to a reduction in series resistance due to promoted metal migration into BCP and optimized optical interference effects in multilayered devices. © 2010 American Chemical Society.

  14. Fatigue crack growth simulations of interfacial cracks in bi-layered FGMs using XFEM

    Science.gov (United States)

    Bhattacharya, S.; Singh, I. V.; Mishra, B. K.; Bui, T. Q.

    2013-10-01

    An investigation of fatigue crack growth of interfacial cracks in bi-layered materials using the extended finite element method is presented. The bi-material consists of two layers of dissimilar materials. The bottom layer is made of aluminium alloy while the upper one is made of functionally graded material (FGM). The FGM layer consists of 100 % aluminium alloy on the left side and 100 % ceramic (alumina) on the right side. The gradation in material property of the FGM layer is assumed to be exponential from the alloy side to the ceramic side. The domain based interaction integral approach is extended to obtain the stress intensity factors for an interfacial crack under thermo-mechanical load. The edge and centre cracks are taken at the interface of bi-layered material. The fatigue life of the interface crack plate is obtained using the Paris law of fatigue crack growth under cyclic mode-I, mixed-mode and thermal loads. This study reveals that the crack propagates into the FGM layer under all types of loads.

  15. Effects of fiber and interfacial layer architectures on the thermoplastic response of metal matrix composites

    Science.gov (United States)

    Pindera, Marek-Jerzy; Freed, Alan D.; Arnold, Steven M.

    1992-01-01

    Examined here is the effect of fiber and interfacial layer morphologies on thermal fields in metal matrix composites (MMCs). A micromechanics model based on an arbitrarily layered concentric cylinder configuration is used to calculate thermal stress fields in MMCs subjected to spatially uniform temperature changes. The fiber is modelled as a layered material with isotropic or orthotropic elastic layers, whereas the surrounding matrix, including interfacial layers, is treated as a strain-hardening, elastoplastic, von Mises solid with temperature-dependent parameters. The solution to the boundary-value problem of an arbitrarily layered concentric cylinder under the prescribed thermal loading is obtained using the local/global stiffness matrix formulation originally developed for stress analysis of multilayered elastic media. Examples are provided that illustrate how the morphology of the SCS6 silicon carbide fiber and the use of multiple compliant layers at the fiber/matrix interface affect the evolution of residual stresses in SiC/Ti composites during fabrication cool-down.

  16. Mechanical and Abrasive Wear Properties of Anodic Oxide Layers Formed on Aluminium

    Institute of Scientific and Technical Information of China (English)

    W.Bensalah; K.Elleuch; M.Feki; M.Wery; H.F.Ayedi

    2009-01-01

    Aluminium oxide coatings were formed on aluminium substrates in oxalic acid-sulphuric acid bath. Abrasion tests of the obtained anodic layers were carried out on a pin-on-disc machine in accordance with the ISO/DP 825 specifications. The Vickers microhardness, D (HV0.2). and the abrasion weight loss, Wa (mg) were measured. Influence of oxalic acid concentration (Cox), bath temperature (T) and anodic current density (J) on D and Wa has been examined, and the sulphuric acid concentration (Caul) was maintained at 160 g.L-1. It was found that high microhardness and abrasive wear resistance of oxide layers were produced under low temperatures and high current densities with the addition of oxalic acid. The morphology and the composition of the anodic oxide layer were examined by scanning electron microscopy (SEM), atomic force microscopy (AFM), optical microscopy and glow-discharge optical emission spectroscopy (GDOES). It was found that the chemistry of the anodizing electrolyte, temperature, and current density are the controlling factors of the mechanical properties of the anodic oxide layer.

  17. 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

  18. Preparation and Evaluation of Multi-Layer Anodes of Solid Oxide Fuel Cell

    Science.gov (United States)

    Santiago, Diana; Farmer, Serene C.; Setlock, John A.

    2012-01-01

    The development of an energy device with abundant energy generation, ultra-high specific power density, high stability and long life is critical for enabling longer missions and for reducing mission costs. Of all different types of fuel cells, the solid oxide fuel cells (SOFC) is a promising high temperature device that can generate electricity as a byproduct of a chemical reaction in a clean way and produce high quality heat that can be used for other purposes. For aerospace applications, a power-to-weight of (is) greater than 1.0 kW/kg is required. NASA has a patented fuel cell technology under development, capable of achieving the 1.0 kW/kg figure of merit. The first step toward achieving these goals is increasing anode durability. The catalyst plays an important role in the fuel cells for power generation, stability, efficiency and long life. Not only the anode composition, but its preparation and reduction are key to achieving better cell performance. In this research, multi-layer anodes were prepared varying the chemistry of each layer to optimize the performance of the cells. Microstructure analyses were done to the new anodes before and after fuel cell operation. The cells' durability and performance were evaluated in 200 hrs life tests in hydrogen at 850 C. The chemistry of the standard nickel anode was modified successfully reducing the anode degradation from 40% to 8.4% in 1000 hrs and retaining its microstructure.

  19. Numerical simulations of the role of a ferroelectric polymer interfacial layer in organic solar cells.

    Science.gov (United States)

    Liu, Bo; Xu, Feng; Zhang, Xinghua; Yan, Dadong; Lu, Dan

    2016-02-21

    A Pauli master equation method is adopted for the simulation of polymer bulk heterojunction (BHJ) solar cells with vinylidene fluoride-trifluoroethylene copolymer (P(VDF-TrFE)) films as interfacial layers. According to previous reports, using highly crystalline P(VDF-TrFE) films as interfacial layers can highly enhance the efficiency of polymer BHJ solar cells, and possible mechanisms for the enhancement by two different groups were given as the dipole induced permanent internal electric field or simply the electrode improvement which implied that the origin is the barrier lowering effect. The correlation between the appearance of S-shaped current density-voltage (J-V) characteristics and the energy barrier is studied first, and then further results indicate that the previous electrode improvement model provides a consistent explanation for the origin of performance enhancement due to the insertion of polarized P(VDF-TrFE) interfacial layers. Moreover, the phenomenon of an increase of the internal electric field observed before can be attributed to better contact conditions which help reduce the bimolecular recombination rate. Comparatively speaking, the electrode improvement model can give a more rational explanation for the origin of performance enhancement experimentally found. In contrast, the dipole induced permanent internal electric field model was not complete enough. PMID:26822850

  20. Layer growth mechanisms on metallic electrodes under anodic polarization in cryolite-alumina melt

    OpenAIRE

    Oudot, Magaly; Cassayre, Laurent; Chamelot, Pierre; Gibilaro, Mathieu; Massot, Laurent; Pijolat, Michèle; Bouvet, Sylvie

    2014-01-01

    The anodic behavior of Fe, Ni, Co electrodes was investigated in a cryolite-alumina melt at 960 °C, by electrochemical techniques, microstructural characterizations and thermodynamic calculations, to provide a fundamental understanding of layers formation at metal (M) electrode surface. At low overpotential, anodic dissolution of M occurs; when the Mn+ concentration at the surface reaches saturation, a MxAl3-xO4 spinel phase precipitates. Then, a dense MyO layer grows at the metal/spinel inte...

  1. Laser-Doping through Anodic Aluminium Oxide Layers for Silicon Solar Cells

    OpenAIRE

    Pei Hsuan Doris Lu; Alison Lennon; Stuart Wenham

    2015-01-01

    This paper demonstrates that silicon can be locally doped with aluminium to form localised p+ surface regions by laser-doping through anodic aluminium oxide (AAO) layers formed on the silicon surface. The resulting p+ regions can extend more than 10 μm into the silicon and the electrically active p-type dopant concentration exceeds 1020 cm−3 for the first 6-7 μm of the formed p+ region. Anodic aluminium oxide layers can be doped with other impurities, such as boron and phosphorus, by anodisin...

  2. Effect of slip boundary conditions on interfacial stability of two-layer viscous fluids under shear

    CERN Document Server

    Patlazhan, Stanislav

    2015-01-01

    The traditional approach in the study of hydrodynamic stability of stratified fluids includes the stick boundary conditions between layers. However, this rule may be violated in polymer systems and as a consequence various instabilities may arise. The main objective of this paper is to analyze theoretically the influence of slip boundary conditions on the hydrodynamic stability of the interface between two immiscible viscous layers subjected to simple shear flow. It is found that the growth rate of long-wave disturbances is fairly sensitive to the slip at the interface between layers as well as at the external boundary. These phenomena are shown to give different contributions to the stability of shear flow depending on viscosity, thickness, and density ratios of the layers. Particularly, the interfacial slip can increase the perturbation growth rate and lead to unstable flow. An important consequence of this effect is the violation of stability for sheared layers with equal viscosities and densities in a bro...

  3. A Novel Method to Determine the Thermal Conductivity of Interfacial Layers Surrounding the Nanoparticles of a Nanofluid

    Directory of Open Access Journals (Sweden)

    Rajinder Pal

    2014-10-01

    Full Text Available Nanofluids are becoming increasingly popular as heat transfer fluids in a variety of industrial applications, due to their enhanced heat transfer characteristics. The thermal conductivity of nanofluids is usually found to be much larger than that predicted from the classical models, such as the Maxwell model. The key mechanism of enhancement of thermal conductivity of dilute nanofluids is the solvation of nanoparticles with a layer of matrix liquid. As of now, little is known quantitatively about the thermal conductivity of the interfacial layers surrounding the nanoparticles. In this article, a novel method is presented to determine the thermal conductivity of the interfacial layers of the nanoparticles. The proposed method allows the estimation of the thermal conductivity of interfacial layers based on the combined measurements of the intrinsic viscosity and intrinsic thermal conductivity of a bulk nanofluid. From the measured intrinsic viscosity of the nanofluid, the thickness of the interfacial layer is estimated. Using the known interfacial layer thickness along with the measured intrinsic thermal conductivity of the nanofluid, the thermal conductivity of the interfacial layer is estimated. The proposed method is validated by simulation and experimental results.

  4. Effect of anodization time on photoluminescence of porous thin SiC layer grown onto silicon

    Energy Technology Data Exchange (ETDEWEB)

    Keffous, A. [Unite de Developpement de la Technologie du Silicium (UDTS), 2, bd. Frantz Fanon, B.P. 399 Alger-Gare Alger (Algeria)]. E-mail: keffousa@yahoo.fr; Bourenane, K. [Unite de Developpement de la Technologie du Silicium (UDTS), 2, bd. Frantz Fanon, B.P. 399 Alger-Gare Alger (Algeria)]. E-mail: bourima2003@yahoo.fr; Kechouane, M. [Universite des Sciences et Technologie Houari Boumediene-Faculte de Physique, 2, bd. Frantz Fanon, B.P. 399 Alger-Gare Alger (Algeria); Gabouze, N. [Unite de Developpement de la Technologie du Silicium (UDTS), 2, bd. Frantz Fanon, B.P. 399 Alger-Gare Alger (Algeria); Kerdja, T. [Centre de Developpement de la Techniques Avancees (CDTA), 2, bd. Frantz Fanon, B.P. 399 Alger-Gare Alger (Algeria); Guerbous, L. [Centre de Recherche Nucleaire d' Alger (CRNA), 2, bd. Frantz Fanon, B.P. 399 Alger-Gare Alger (Algeria); Lafane, S. [Centre de Developpement de la Techniques Avancees (CDTA), 2, bd. Frantz Fanon, B.P. 399 Alger-Gare Alger (Algeria)

    2007-10-15

    A porous SiC (PSC) layer was fabricated by anodization of a 1.6 {mu}m thin SiC layer deposited onto p-type Si(1 0 0) substrate by pulsed laser deposition (PLD), using a hot-pressed 6H-SiC(p) as sputtered target. p-Type PSC layers were fabricated by anodization in HF/ethylene glycol electrolyte (1:1 by vol.) at different etching times. The properties of the PSC layer formed by this method were investigated by X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM) and photoluminescence (PL). The results show, that the growth layer was crystalline and PL spectra exhibit blue band emission centered at 2.95 eV. In addition, the results indicate clearly an increase in PL intensity by ten times of magnitude compared to that exhibited by the unetched sample.

  5. Effect of anodization time on photoluminescence of porous thin SiC layer grown onto silicon

    International Nuclear Information System (INIS)

    A porous SiC (PSC) layer was fabricated by anodization of a 1.6 μm thin SiC layer deposited onto p-type Si(1 0 0) substrate by pulsed laser deposition (PLD), using a hot-pressed 6H-SiC(p) as sputtered target. p-Type PSC layers were fabricated by anodization in HF/ethylene glycol electrolyte (1:1 by vol.) at different etching times. The properties of the PSC layer formed by this method were investigated by X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM) and photoluminescence (PL). The results show, that the growth layer was crystalline and PL spectra exhibit blue band emission centered at 2.95 eV. In addition, the results indicate clearly an increase in PL intensity by ten times of magnitude compared to that exhibited by the unetched sample

  6. Improvement of the interfacial Dzyaloshinskii-Moriya interaction by introducing a Ta buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nam-Hui; Jung, Jinyong; Cho, Jaehun; You, Chun-Yeol, E-mail: cyyou@inha.ac.kr [Department of Physics, Inha University, Incheon 402-751 (Korea, Republic of); Han, Dong-Soo; Kim, June-Seo, E-mail: spin2mtj@gmail.com; Swagten, Henk J. M. [Department of Applied Physics, Center for NanoMaterials, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands)

    2015-10-05

    We report systematic measurements of the interfacial Dzyaloshinskii-Moriya interaction (iDMI) by employing Brillouin light scattering in Pt/Co/AlO{sub x} and Ta/Pt/Co/AlO{sub x} structures. By introducing a tantalum buffer layer, the saturation magnetization and the interfacial perpendicular magnetic anisotropy are significantly improved due to the better interface between heavy metal and ferromagnetic layer. From the frequency shift between Stokes- and anti-Stokes spin-waves, we successively obtain considerably larger iDM energy densities (D{sub max} = 1.65 ± 0.13 mJ/m{sup 2} at t{sub Co} = 1.35 nm) upon adding the Ta buffer layer, despite the nominally identical interface materials. Moreover, the energy density shows an inverse proportionality with the Co layer thickness, which is the critical clue that the observed iDMI is indeed originating from the interface between the Pt and Co layers.

  7. The formation of rag layers and the role of interfacial partition of naphthenates and asphaltenes

    Energy Technology Data Exchange (ETDEWEB)

    Moran, K. [Syncrude, Edmonton, AB (Canada); Kiran, S.; Acosta, E.J. [Toronto Univ., ON (Canada). Dept. of Chemical Engineering and Applied Chemistry

    2008-07-01

    Stable emulsions of oil and water are known as rag layers and have been associated with the precipitation of asphaltenes and the formation of liquid crystal phases. This paper presented optical microscopy studies of rag layers produced under different conditions. Liquid crystal formation was observed only under specific conditions, such as in the presence of un-dissociated naphthenic acids. Liquid crystal phases were not observed in the absence of naphthenic acids or in the presence of sodium naphthenates. The formation of rag layer was associated to the fraction of asphaltene where the oil was reduced. Optical micrographs showed that the droplets of oil and/or water in the rag layer were not stabilized by the particles of asphaltene precipitated. These observations were explained using a hypothesis of asphaltene interfacial partition, whereby the asphaltene molecules accumulate near the oil/water interface to form skins that inhibit their coalescence and separation.

  8. Effects of image charges, interfacial charge discreteness, and surface roughness on the zeta potential of spherical electric double layers

    Science.gov (United States)

    Gan, Zecheng; Xing, Xiangjun; Xu, Zhenli

    2012-07-01

    We investigate the effects of image charges, interfacial charge discreteness, and surface roughness on spherical electric double layer structures in electrolyte solutions with divalent counterions in the setting of the primitive model. By using Monte Carlo simulations and the image charge method, the zeta potential profile and the integrated charge distribution function are computed for varying surface charge strengths and salt concentrations. Systematic comparisons were carried out between three distinct models for interfacial charges: (1) SURF1 with uniform surface charges, (2) SURF2 with discrete point charges on the interface, and (3) SURF3 with discrete interfacial charges and finite excluded volume. By comparing the integrated charge distribution function and the zeta potential profile, we argue that the potential at the distance of one ion diameter from the macroion surface is a suitable location to define the zeta potential. In SURF2 model, we find that image charge effects strongly enhance charge inversion for monovalent interfacial charges, and strongly suppress charge inversion for multivalent interfacial charges. For SURF3, the image charge effect becomes much smaller. Finally, with image charges in action, we find that excluded volumes (in SURF3) suppress charge inversion for monovalent interfacial charges and enhance charge inversion for multivalent interfacial charges. Overall, our results demonstrate that all these aspects, i.e., image charges, interfacial charge discreteness, their excluding volumes, have significant impacts on zeta potentials of electric double layers.

  9. Electron transfer through solid-electrolyte-interphase layers formed on Si anodes of Li-ion batteries

    International Nuclear Information System (INIS)

    Solid-electrolyte interphase (SEI) films are formed on the electrode surfaces due to aggregation of products of reduction or oxidation of the electrolyte. These films may grow to thicknesses in the order of 50-100 nm and contain a variety of organic and inorganic products but their structure is not well defined. Although in some cases the films exert a passivating role, this is not always the case, and these phenomena are particularly more complex on Silicon anodes due to swelling and cracking of the electrode during lithiation and delithiation. Since the driving force for SEI growth is electron transfer, it is important to understand how electron transfer may keep occurring through the heterogeneous film once the bare electron surface is covered. Here we introduce a novel approach for studying electron transfer through model films and show preliminary results for the analysis of electron transfer through model composite interfacial systems integrated by electrode/SEI layer/electrolyte. Ab initio molecular dynamics simulations are used to identify deposition of SEI components, and a density functional theory/Green's function approach is utilized for characterizing electron transfer. Three degrees of lithiation are modeled for the electrodes, the SEI film is composed by LiF or Li2O, and the ethylene carbonate reduction is studied. An applied potential is used as driving force for the leakage current, which is evaluated as a function of the applied potential. Comparative analyses are done for LiF and Li2O model SEI layers

  10. In situ formation of graphene layers on graphite surfaces for efficient anodes of microbial fuel cells.

    Science.gov (United States)

    Tang, Jiahuan; Chen, Shanshan; Yuan, Yong; Cai, Xixi; Zhou, Shungui

    2015-09-15

    Graphene can be used to improve the performance of the anode in a microbial fuel cell (MFC) due to its good biocompatibility, high electrical conductivity and large surface area. However, the chemical production and modification of the graphene on the anode are environmentally hazardous because of the use of various harmful chemicals. This study reports a novel method based on the electrochemical exfoliation of a graphite plate (GP) for the in situ formation of graphene layers on the surface of a graphite electrode. When the resultant graphene-layer-based graphite plate electrode (GL/GP) was used as an anode in an MFC, a maximum power density of 0.67 ± 0.034 W/m(2) was achieved. This value corresponds to 1.72-, 1.56- and 1.26-times the maximum power densities of the original GP, exfoliated-graphene-modified GP (EG/GP) and chemically-reduced-graphene-modified GP (rGO/GP) anodes, respectively. Electrochemical measurements revealed that the high performance of the GL/GP anode was attributable to its macroporous structure, improved electron transfer and high electrochemical capacitance. The results demonstrated that the proposed method is a facile and environmentally friendly synthesis technique for the fabrication of high-performance graphene-based electrodes for use in microbial energy harvesting. PMID:25950933

  11. Interfacially polymerized layers for oxygen enrichment: a method to overcome Robeson's upper-bound limit.

    Science.gov (United States)

    Tsai, Ching-Wei; Tsai, Chieh; Ruaan, Ruoh-Chyu; Hu, Chien-Chieh; Lee, Kueir-Rarn

    2013-06-26

    Interfacial polymerization of four aqueous phase monomers, diethylenetriamine (DETA), m-phenylenediamine (mPD), melamine (Mela), and piperazine (PIP), and two organic phase monomers, trimethyl chloride (TMC) and cyanuric chloride (CC), produce a thin-film composite membrane of polymerized polyamide layer capable of O2/N2 separation. To achieve maximum efficiency in gas permeance and O2/N2 permselectivity, the concentrations of monomers, time of interfacial polymerization, number of reactive groups in monomers, and the structure of monomers need to be optimized. By controlling the aqueous/organic monomer ratio between 1.9 and 2.7, we were able to obtain a uniformly interfacial polymerized layer. To achieve a highly cross-linked layer, three reactive groups in both the aqueous and organic phase monomers are required; however, if the monomers were arranged in a planar structure, the likelihood of structural defects also increased. On the contrary, linear polymers are less likely to result in structural defects, and can also produce polymer layers with moderate O2/N2 selectivity. To minimize structural defects while maximizing O2/N2 selectivity, the planar monomer, TMC, containing 3 reactive groups, was reacted with the semirigid monomer, PIP, containing 2 reactive groups to produce a membrane with an adequate gas permeance of 7.72 × 10(-6) cm(3) (STP) s(-1) cm(-2) cm Hg(-1) and a high O2/N2 selectivity of 10.43, allowing us to exceed the upper-bound limit of conventional thin-film composite membranes. PMID:23731366

  12. The function of microporous layers and the interaction between the anode and cathode in DMFCs

    DEFF Research Database (Denmark)

    Zhang, H. F.; Wang, SY; Pei, PC;

    2008-01-01

    A combined effect of microporous layers (MPLs) on direct methanol fuel cells (DMFCs) is investigated. From the distribution of the outstanding carbon loading combinations of the cathode MPL and anode MPL as well as the evolutions of polarization curves, a combined effect in which the contributions...... of the two MPLs interdepend is observed. A further discussion indicates that either MPL in DMFCs is of double roles: a side role of obstructing mass transfers and a main role of adjusting an interaction between the anode and cathode. It is inferred that it is the combination of the two roles that produces...

  13. Anode behavior of Sn/WC/graphene triple layered composite for lithium-ion batteries

    International Nuclear Information System (INIS)

    Graphical abstract: A Sn/WC/graphene triple layered composite synthesized via a simple ball-milling approach shows excellent cycling stability and rate capability when used as anode for lithium-ion batteries. Also a (Sn/WC/G)/LiNi0.5Mn1.5O4 full cell exhibits a discharge capacity of 399 mAh (g of Sn/WC/G anode)−1 with superior cyclability, demonstrates full utilization of the anode and an expected energy density value of 530 Wh kg−1, showing a prospect for practical lithium-ion battery applications. -- Abstract: Sn/WC/graphene (Sn/WC/G) triple layered composite in which Sn thin-layer (3–10 nm) enwrapped in-between WC (tungsten carbide) substrate and few-layer graphene is prepared via a simple two-step ball-milling approach. The as prepared triple layered composite exhibits superior cyclability with high capacity and rate capability in lithium-ion half cells, i.e., ca. retains 91% of its initial capacity (400 mAh g−1) after 100 cycles and delivers a high capacity of ∼200 mAh g−1 at a very high rate of 8 C (4000 mA g−1). The improvement in the electrochemical performance can be attributed to the triple layered structure in which the inner WC and outer graphene conductive buffer matrix not only can buffer the volume changes of the Sn thin-layer during cycling, but also ensure good electrical contact of the electro-active particles. Furthermore, a full cell coupled with spinel LiNi0.5Mn1.5O4 cathode in this paper demonstrates full utilization of the Sn anode and an expected energy density value of 530 Wh kg−1, showing a prospect for practical lithium-ion battery applications

  14. Effects of disorder state and interfacial layer on thermal transport in copper/diamond system

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, V., E-mail: vikas.sinha.1.ctr@us.af.mil [Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433 (United States); UES, Inc., 4401 Dayton-Xenia Road, Dayton, Ohio 45432 (United States); Gengler, J. J. [Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433 (United States); Spectral Energies, LLC, 5100 Springfield Street, Suite 301, Dayton, Ohio 45431 (United States); Muratore, C. [Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433 (United States); University of Dayton Research Institute, 300 College Park, Dayton, Ohio 45469 (United States); Spowart, J. E. [Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433 (United States)

    2015-02-21

    The characterization of Cu/diamond interface thermal conductance (h{sub c}) along with an improved understanding of factors affecting it are becoming increasingly important, as Cu-diamond composites are being considered for electronic packaging applications. In this study, ∼90 nm thick Cu layers were deposited on synthetic and natural single crystal diamond substrates. In several specimens, a Ti-interface layer of thickness ≤3.5 nm was sputtered between the diamond substrate and the Cu top layer. The h{sub c} across Cu/diamond interfaces for specimens with and without a Ti-interface layer was determined using time-domain thermoreflectance. The h{sub c} is ∼2× higher for similar interfacial layers on synthetic versus natural diamond substrate. The nitrogen concentration of synthetic diamond substrate is four orders of magnitude lower than natural diamond. The difference in nitrogen concentration can lead to variations in disorder state, with a higher nitrogen content resulting in a higher level of disorder. This difference in disorder state potentially can explain the variations in h{sub c}. Furthermore, h{sub c} was observed to increase with an increase of Ti-interface layer thickness. This was attributed to an increased adhesion of Cu top layer with increasing Ti-interface layer thickness, as observed qualitatively in the current study.

  15. Au Nanoparticles as Interfacial Layer for CdS Quantum Dot-sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Zhu Guang

    2010-01-01

    Full Text Available Abstract Quantum dot-sensitized solar cells based on fluorine-doped tin oxide (FTO/Au/TiO2/CdS photoanode and polysulfide electrolyte are fabricated. Au nanoparticles (NPs as interfacial layer between FTO and TiO2 layer are dip-coated on FTO surface. The structure, morphology and impedance of the photoanodes and the photovoltaic performance of the cells are investigated. A power conversion efficiency of 1.62% has been obtained for FTO/Au/TiO2/CdS cell, which is about 88% higher than that for FTO/TiO2/CdS cell (0.86%. The easier transport of excited electron and the suppression of charge recombination in the photoanode due to the introduction of Au NP layer should be responsible for the performance enhancement of the cell.

  16. Titanium dioxide prepared by APCVD for using as an interfacial layer in polymer solar cells

    International Nuclear Information System (INIS)

    Highlights: • TiO2 thin films were grown on ITO using TiCl4. • The growth temperature does not exceed 490 °C in any step of the synthesis. • TiO2 films prepared present interesting optical and electrical properties for organic solar cells application. • Increasing in Jsc and η parameters is observed with the insertion of the TiO2 interfacial layer and at first annealing. • Observed similar results can be obtained either by varying the annealing temperature or the annealing time. - Abstract: Titanium dioxide TiO2 thin films have been prepared by APCVD method using TiCl4 as a precursor. The surface morphology of the films deposited was investigated by scanning electron microscopy (SEM). The ellipsometry was used to determinate the refractive index of the films deposited at 490 °C and the resistivity was obtained using Hall effect measurement. Transmittance of TiO2 films deposited on ITO was measured by UV–visible spectroscopy. TiO2 films which are prepared during 5 min present a resistivity of 4.2 × 10−4 Ω cm, a transmittance higher than 80% and a refractive index of 1,8. These films can be used as interfacial layer in organic solar cells application to minimize the reflectivity and improve solar cells efficiency. Increasing in short-circuit courant density (Jsc) and efficiency (η) parameters is observed with the insertion of the TiO2 interfacial layer after the first annealing

  17. Layered and interfacially blended polyelectrolyte multi-walled carbon nanotube composites for enhanced ionic conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Gu Xianke [Department of Chemical Engineering, University of Washington, Seattle, WA 98115-1750 (United States); School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China); Knorr, Daniel B. [Department of Chemical Engineering, University of Washington, Seattle, WA 98115-1750 (United States); Macromolecular Science and Technology Branch, United States Army Research Laboratory, Aberdeen Proving Ground, MD 21009 (United States); Wang Guojian [School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China); Overney, Rene M., E-mail: roverney@u.washington.edu [Department of Chemical Engineering, University of Washington, Seattle, WA 98115-1750 (United States)

    2012-01-01

    To enhance the ionic conductivity in solid phase polyelectrolyte systems for lithium ion battery applications demands effective control of the phase properties. Here, we report on a strategy involving a layer-by-layer methodology of two polyelectrolytes, poly(ethylene oxide) (PEO) and poly(acrylic) acid (PAA) and carboxylic acid functionalized multi-walled carbon nanotubes (MWNTs). Optimization of the assembly strategy revealed that undoped and lithium-ion doped stacking of four layers provides excellent film growth and improvement of the ionic conductivity of up to 10{sup -5} S cm{sup -1}, which exceeds conventional assemblies of lithium-ion doped [PEO/PAA] by up to two orders of magnitude. Although ionic conductivity was most effectively enhanced for ultrathin films (< 100 nm), [PEO/PAA/PEO/(PAA + MWNT)] stacking still provides an ionic conductivity of > 10{sup -6} S cm{sup -1} for thick films (> 2 {mu}m). The improvement of ionic conductivity was attributed to (i) interfacial phase mixing (blending) of the two polyelectrolytes, (ii) the MWNT contribution in the interfacial region, and (iii) the preferential adsorption of lithium-ions along the carbon nanotubes. This study involved a series of scanning probe methods including lateral force microscopy, and electrostatic force microscopy.

  18. Thermal conduction in polymeric nanofluids under mean field approximation: role of interfacial adsorption layers

    Science.gov (United States)

    Nisha, M. R.; Philip, J.

    2013-07-01

    Polymeric nanofluids of TiO2/PVA (polyvinyl alcohol) and Cu/PVA have been prepared by dispersing nanoparticles of TiO2 or metallic copper in PVA. The thermal diffusivities and thermal conductivities of these nanofluids have been measured as a function of particle loading following a thermal wave interference technique in a thermal wave resonant cavity. It is found that in both cases thermal conductivity increases with particle concentration, with Cu/PVA nanofluids showing a much larger increase. The results have been compared with the corresponding values calculated following different theoretical models. Comparison of the results with model-based calculations shows that the thermal conductivity variations in these nanofluids are within the framework of the classical mean field theory including the formation of thin interfacial adsorption layers around nanoparticles. Although the molecular weight of PVA is very high, it is found that the adsorption layer thickness is limited by the hydrodynamic radius of the nanoparticles. It is found that particle clustering followed by interfacial layering accounts for the larger increase in thermal conductivity found for Cu/PVA compared to TiO2/PVA.

  19. Performance enhancement in inverted solar cells by interfacial modification of ZnO nanoparticle buffer layer.

    Science.gov (United States)

    Ambade, Swapnil B; Ambade, Rohan B; Kim, Seojin; Park, Hanok; Yoo, Dong Jin; Leel, Soo-Hyoung

    2014-11-01

    Polymer solar cells (PSCs) have attracted increasing attention in recent years. The rapid progress and mounting interest suggest the feasibility of PSC commercialization. However, critical issues such as stability and the weak nature of their interfaces posses quite a challenge. In the context of improving stability, PSCs with inverted geometry consising of inorganic oxide layer acting as an n-buffer offer quite the panacea. Zinc oxide (ZnO) is one of the most preferred semiconducting wide band gap oxides as an efficient cathode layer that effectively extracts and transports photoelectrons from the acceptor to the conducting indium-doped tin oxide (ITO) due to its high conductivity and transparency. However, the existence of a back charge transfer from metal oxides to electron-donating conjugated polymer and poor contact with the bulk heterojunction (BHJ) active layer results in serious interfacial recombination and leads to relatively low photovoltaic performance. One approach to improving the performance and charge selectivity of these types of inverted devices consists of modifying the interface between the inorganic metal oxide (e.g., ZnO) and organic active layer using a sub-monolayer of interfacial materials (e.g., functional dyes). In this work, we demonstrate that the photovoltaic parameters of inverted solar cells comprising a thin overlayer of functional dyes over ZnO nanoparticle as an n-buffer layer are highly influenced by the anchoring groups they possess. While an inverted PSC containing an n-buffer of only ZnO exhibited an overall power conversion efficiency (PCE) of 2.87%, the devices with an interlayer of dyes containing functional cyano-carboxylic, cyano-cyano, and carboxylic groups exhibited PCE of 3.52%, 3.39%, and 3.21%, respectively, due to increased forward charge collection resulting from enhanced electronic coupling between the ZnO and BHJ active layers. PMID:25958563

  20. Electrostatically self-assembled nonconjugated polyelectrolytes as an ideal interfacial layer for inverted polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Hongkyu; Hong, Soonil; Lee, Jongjin; Lee, Kwanghee [School of Materials Science and Engineering, Heeger Center for Advanced Materials, Research Institute for Solar and Sustainable Energies, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

    2012-06-12

    Nonconjugated polyelectrolytes (NPEs) are ideal interfacial layers for high-efficiency inverted polymer solar cells (I-PSCs). The NPEs are coated on indium tin oxide (ITO) using ionic self-assembly. Due to dipole formation between the cationic amine of the NPE and the anionic oxygen of ITO, the work function of ITO is dramatically reduced from 4.8 to 4.0 eV. Using the modified ITO, UV-independent I-PSCs with high efficiencies of 6.3% are demonstrated. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Effects of anode buffer layers on the properties of organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kun Ho; Gong, Su Cheol; Chang, Ho Jung, E-mail: hjchang@dankook.ac.kr

    2012-10-30

    We fabricated organic solar cells (OSCs) using a poly(3-hexythiophene) (P3HT) and methanofullerene(6,6)-phenyl C61 butyric acid methyl ester (PCBM) active layer for the electron donor and acceptor materials, respectively. The active layer was spin-coated onto various substrates with different anode buffer layer positions, such as lithium fluoride (LiF)/indium tin oxide (ITO)/glass (device A), poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/ITO/glass (device B) and LiF/PEDOT:PSS/ITO/glass (device C). The effects of the anode buffer layer position on the electrical and morphological properties of the devices were investigated. The performance of the OSC coated on the device C substrate showed the best electrical property among the other samples, indicating that the maximum short circuit current density, open circuit voltage, fill factor and power conversion efficiency values were about 9.1 mA/cm{sup 2}, 0.65 V, 54.1% and 3.2%, respectively. The LiF buffer layer deposited on the PEDOT:PSS/ITO substrate (device C) showed a smooth film roughness and a lower contact angle compared to the other samples, which led to an improvement of the hole injection efficiency into the anode electrode.

  2. Interfacial analysis of InP surface preparation using atomic hydrogen cleaning and Si interfacial control layers prior to MgO deposition

    International Nuclear Information System (INIS)

    The objective of this study is to investigate how the surface characteristics of indium phosphide (InP) can be modified through the use of atomic hydrogen (H*) cleaning and silicon interfacial control layers (Si ICL), prior to the deposition of MgO dielectric layers. X-ray photoelectron spectroscopy (XPS) analysis shows that the InP native oxide can be successfully removed using atomic hydrogen cleaning at a substrate temperature of 300 deg. C. However, atomic force microscopy (AFM) images display evidence for the growth of metallic In island features after H* cleaning, and subsequent deposition of MgO thin films on the H* cleaned surface resulted in high levels of interfacial indium oxide growth. It has also been shown that the deposition of thin (∼1 nm) Si layers on InP native oxide surfaces results in the transfer of oxygen from the InP substrate to the Si ICL and the formation of Si-InP bonds. XPS analysis indicates that MgO deposition and subsequent 500 deg. C annealing results in further oxidation of the Si layer. However, no evidence for the re-growth of interfacial In or P oxide species was observed, in contrast to observations on the H* cleaned surface.

  3. Layered reduced graphene oxide with nanoscale interlayer gaps as a stable host for lithium metal anodes

    Science.gov (United States)

    Lin, Dingchang; Liu, Yayuan; Liang, Zheng; Lee, Hyun-Wook; Sun, Jie; Wang, Haotian; Yan, Kai; Xie, Jin; Cui, Yi

    2016-07-01

    Metallic lithium is a promising anode candidate for future high-energy-density lithium batteries. It is a light-weight material, and has the highest theoretical capacity (3,860 mAh g–1) and the lowest electrochemical potential of all candidates. There are, however, at least three major hurdles before lithium metal anodes can become a viable technology: uneven and dendritic lithium deposition, unstable solid electrolyte interphase and almost infinite relative dimension change during cycling. Previous research has tackled the first two issues, but the last is still mostly unsolved. Here we report a composite lithium metal anode that exhibits low dimension variation (∼20%) during cycling and good mechanical flexibility. The anode is composed of 7 wt% ‘lithiophilic’ layered reduced graphene oxide with nanoscale gaps that can host metallic lithium. The anode retains up to ∼3,390 mAh g–1 of capacity, exhibits low overpotential (∼80 mV at 3 mA cm–2) and a flat voltage profile in a carbonate electrolyte. A full-cell battery with a LiCoO2 cathode shows good rate capability and flat voltage profiles.

  4. Layer growth mechanisms on metallic electrodes under anodic polarization in cryolite-alumina melt

    International Nuclear Information System (INIS)

    Highlights: •Oxidation mechanisms of Fe, Ni and Co were studied at low potential in cryolite alumina melt. •At low overpotential, anodic dissolution of metal M occurs. •At the metal surface, Mn+ react with Al3+ and O2− to form an Al-containing spinel. •A minimal current density is required to precipitate the spinel phase. •With further polarization, a monoxide layer grows at the metal/spinel interface. -- Abstract: The anodic behavior of Fe, Ni, Co electrodes was investigated in a cryolite-alumina melt at 960 °C, by electrochemical techniques, microstructural characterizations and thermodynamic calculations, to provide a fundamental understanding of layers formation at metal (M) electrode surface. At low overpotential, anodic dissolution of M occurs; when the Mn+ concentration at the surface reaches saturation, a MxAl3−xO4 spinel phase precipitates. Then, a dense MyO layer grows at the metal/spinel interface. As for Fe, polarization at higher overpotentials lead to the same layers of spinel and monoxide, but pores at the metal/FeyO interface cause loss of adhesion of the oxide film

  5. Laser-Doping through Anodic Aluminium Oxide Layers for Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Pei Hsuan Doris Lu

    2015-01-01

    Full Text Available This paper demonstrates that silicon can be locally doped with aluminium to form localised p+ surface regions by laser-doping through anodic aluminium oxide (AAO layers formed on the silicon surface. The resulting p+ regions can extend more than 10 μm into the silicon and the electrically active p-type dopant concentration exceeds 1020 cm−3 for the first 6-7 μm of the formed p+ region. Anodic aluminium oxide layers can be doped with other impurities, such as boron and phosphorus, by anodising in electrolytes containing the extrinsic impurities in ionic form. The ions become trapped in the formed anodic oxide during anodisation, therefore enabling the impurity to be introduced into the silicon, with aluminium, during laser-doping. This codoping process can be used to create very heavily doped surface layers which can reduce contact resistance on metallisation, whilst the deeper doping achieved by the intrinsic aluminium may act to shield the surface from minority carriers. laser-doping through AAO layers can be performed without introducing any voids in the silicon or fumes which may be harmful to human health.

  6. High power direct methanol fuel cell with a porous carbon nanofiber anode layer

    International Nuclear Information System (INIS)

    Highlights: • This study demonstrates a novel porous carbon nanofiber anode (PNCF) layer. • PNFC anode layer DMFC presents power density of 23.0 mW cm−2. • This unit operates at room temperature and consumes low concentration of methanol. - Abstract: Three anode electrodes containing Pt–Ru Black as a catalyst were fabricated with a porous layer made with different carbon materials: carbon black (CB), carbon nanofiber (CNF) and a combination of both carbon materials (CB + CNF). The carbon-based porous layer was coated onto a carbon cloth with PTFE pre-treatment for delivering hydrophobic properties and applied in direct methanol fuel cells (DMFCs). Characterisation of electrochemical properties for three different anode electrodes was performed with cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) at room temperature in a half-cell configuration. The evolution of the surface morphology of diffusion layer and electrodes was characterised by using variable-pressure scanning electron microscopy (VP-SEM). The electrochemical results indicate that electrode with CNF layer showed the highest current densities compared to CB and CB + CNF with the same catalyst loading. VP-SEM measurements show the network formation within the structure, which could facilitate the methanol mass transfer and improve the catalyst efficiency. The electrodes were applied to a single-cell DMFC, and the cell performance was experimentally investigated under passive operating mode and room temperature. A maximum power density of 23.0 mW cm−2 at a current density of 88.0 mA cm−2 with a 3 M dilute methanol solution was achieved. The results show that the electrodes with a CNF layer could improve the performance of DMFC as compared with commercially used CB and prove it’s potentially application in DMFC technology especially for portable power source applications due to several advantages as followings: operating at low concentration of

  7. A sodium-ion battery exploiting layered oxide cathode, graphite anode and glyme-based electrolyte

    Science.gov (United States)

    Hasa, Ivana; Dou, Xinwei; Buchholz, Daniel; Shao-Horn, Yang; Hassoun, Jusef; Passerini, Stefano; Scrosati, Bruno

    2016-04-01

    Room-temperature rechargeable sodium-ion batteries (SIBs), in view of the large availability and low cost of sodium raw materials, represent an important class of electrochemical systems suitable for application in large-scale energy storage. In this work, we report a novel, high power SIB formed by coupling the layered P2-Na0.7CoO2 cathode with the graphite anode in an optimized ether-based electrolyte. The study firstly addresses the electrochemical optimization of the two electrode materials and then the realization and characterization of the novel SIB based on their combination. The cell represents an original sodium rocking chair battery obtained combining the intercalation/de-intercalation processes of sodium within the cathode and anode layers. We show herein that this battery, favored by suitable electrode/electrolyte combination, offers unique performance in terms of cycle life, efficiency and, especially, power capability.

  8. Ultrasonic Measurement of Interfacial Layer Thickness of Sub-Quarter-Wavelength

    International Nuclear Information System (INIS)

    This paper describes a new technique for thickness measurement of a very thin layer less than one-quarter of the wavelength of ultrasonic wave used in the ultrasonic pulse-echo measurements. The technique determines the thickness of a thin layer in a tapered medium from constructive interference of multiple reflection waves. The interference characteristics are derived and investigated in theoretical and experimental approaches. Modified total reflection wave g(t) defined as difference between total and first reflection waves increases in amplitude as the interfacial layer thickness decreases down to zero. A layer thickness less than one-tenth of the ultrasonic wavelength is measured using the maximum amplitude of g(t) with a good accuracy and sensitivity. The method also requires no inversion process to extract the thickness information from the waveforms of reflected waves, so that it makes possible to have the on-line thickness measurement of a thin layer such as a lubricating oil film in thrust bearings and journal bearings during manufacturing process

  9. Effects of cathode electrolyte interfacial (CEI) layer on long term cycling of all-solid-state thin-film batteries

    Science.gov (United States)

    Wang, Ziying; Lee, Jungwoo Z.; Xin, Huolin L.; Han, Lili; Grillon, Nathanael; Guy-Bouyssou, Delphine; Bouyssou, Emilien; Proust, Marina; Meng, Ying Shirley

    2016-08-01

    All-solid-state lithium-ion batteries have the potential to not only push the current limits of energy density by utilizing Li metal, but also improve safety by avoiding flammable organic electrolyte. However, understanding the role of solid electrolyte - electrode interfaces will be critical to improve performance. In this study, we conducted long term cycling on commercially available lithium cobalt oxide (LCO)/lithium phosphorus oxynitride (LiPON)/lithium (Li) cells at elevated temperature to investigate the interfacial phenomena that lead to capacity decay. STEM-EELS analysis of samples revealed a previously unreported disordered layer between the LCO cathode and LiPON electrolyte. This electrochemically inactive layer grew in thickness leading to loss of capacity and increase of interfacial resistance when cycled at 80 °C. The stabilization of this layer through interfacial engineering is crucial to improve the long term performance of thin-film batteries especially under thermal stress.

  10. Influence of a thin interfacial oxide layer on the ion beam assisted epitaxial crystallization of deposited Si

    Science.gov (United States)

    Priolo, F.; La Ferla, A.; Spinella, C.; Rimini, E.; Ferla, G.; Baroetto, F.; Licciardello, A.

    1988-12-01

    The epitaxial crystallization of chemical vapor deposited Si layers on Si substrates with a thin interfacial oxide layer was induced by a 600 keV Kr beam in the temperature range 350-500 °C. During irradiation the single crystal-amorphous interface velocity was measured in situ by monitoring the reflectivity of He-Ne laser light. We show that a critical irradiation dose is needed before the interfacial oxide breaks down and epitaxial regrowth can take place. This critical dose depends exponentially on the reciprocal temperature with an activation energy of 0.44 eV.

  11. Thermal stability and growth kinetics of the interfacial TiC layer in the Ti alloy/carbon steel system

    International Nuclear Information System (INIS)

    The thermal stability and growth kinetics of the titanium carbide interfacial layer, formed in the course of the diffusion bonding of low-alloy carbon steel (0.3 wt.% C) and Ti alloy, were investigated. Thermal stability of the titanium carbide interfacial layer was evaluated based on the thermodynamic analysis of the Fe–Ti–C ternary system. Thermodynamic analysis of the Fe–Ti–C system confirmed that the titanium carbide layer is stable in contact with the steel part of the diffusion couple. An experiment with inert markers at the interface confirms that growth kinetics of the TiC layer is governed by carbon diffusion from steel to titanium alloy through the titanium carbide phase. In the 800–950 °C temperature range, carbon diffusion in austenite was found to be a rate-determining step of the titanium carbide layer growth during the initial stage of the interaction (<40 min). For advanced stages, the thickness of the layer depends on two simultaneously occurring processes, namely flow of carbon atoms through the titanium carbide layer and that from the titanium carbide layer into the titanium alloy. The estimated values of the carbon diffusion coefficient and the activation energy of the process reflect the grain boundary mechanism of carbon diffusion through the interfacial layer

  12. A layer-by-layer ZnO nanoparticle-PbS quantum dot self-assembly platform for ultrafast interfacial electron injection

    KAUST Repository

    Eita, Mohamed Samir

    2014-08-28

    Absorbent layers of semiconductor quantum dots (QDs) are now used as material platforms for low-cost, high-performance solar cells. The semiconductor metal oxide nanoparticles as an acceptor layer have become an integral part of the next generation solar cell. To achieve sufficient electron transfer and subsequently high conversion efficiency in these solar cells, however, energy-level alignment and interfacial contact between the donor and the acceptor units are needed. Here, the layer-by-layer (LbL) technique is used to assemble ZnO nanoparticles (NPs), providing adequate PbS QD uptake to achieve greater interfacial contact compared with traditional sputtering methods. Electron injection at the PbS QD and ZnO NP interface is investigated using broadband transient absorption spectroscopy with 120 femtosecond temporal resolution. The results indicate that electron injection from photoexcited PbS QDs to ZnO NPs occurs on a time scale of a few hundred femtoseconds. This observation is supported by the interfacial electronic-energy alignment between the donor and acceptor moieties. Finally, due to the combination of large interfacial contact and ultrafast electron injection, this proposed platform of assembled thin films holds promise for a variety of solar cell architectures and other settings that principally rely on interfacial contact, such as photocatalysis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Ru nanostructure fabrication using an anodic aluminum oxide nanotemplate and highly conformal Ru atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Woo-Hee; Park, Sang-Joon; Son, Jong-Yeog; Kim, Hyungjun [Department of Material Science and Engineering, POSTECH Pohang University of Science and Technology, San 31, Hyoja-Dong, Nam-Gu, Pohang 790-784 (Korea, Republic of)

    2008-01-30

    We fabricated metallic nanostructures directly on Si substrates through a hybrid nanoprocess combining atomic layer deposition (ALD) and a self-assembled anodic aluminum oxide (AAO) nanotemplate. ALD Ru films with Ru(DMPD)(EtCp) as a precursor and O{sub 2} as a reactant exhibited high purity and low resistivity with negligible nucleation delay and low roughness. These good growth characteristics resulted in the excellent conformality for nanometer-scale vias and trenches. Additionally, AAO nanotemplates were fabricated directly on Si and Ti/Si substrates through a multiple anodization process. AAO nanotemplates with various hole sizes (30-100 nm) and aspect ratios (2:1-20:1) were fabricated by controlling the anodizing process parameters. The barrier layers between AAO nanotemplates and Si substrates were completely removed by reactive ion etching (RIE) using BCl{sub 3} plasma. By combining the ALD Ru and the AAO nanotemplate, Ru nanostructures with controllable sizes and shapes were prepared on Si and Ti/Si substrates. The Ru nanowire array devices as a platform for sensor devices exhibited befitting properties of good ohmic contact and high surface/volume ratio.

  14. Ru nanostructure fabrication using an anodic aluminum oxide nanotemplate and highly conformal Ru atomic layer deposition.

    Science.gov (United States)

    Kim, Woo-Hee; Park, Sang-Joon; Son, Jong-Yeog; Kim, Hyungjun

    2008-01-30

    We fabricated metallic nanostructures directly on Si substrates through a hybrid nanoprocess combining atomic layer deposition (ALD) and a self-assembled anodic aluminum oxide (AAO) nanotemplate. ALD Ru films with Ru(DMPD)(EtCp) as a precursor and O(2) as a reactant exhibited high purity and low resistivity with negligible nucleation delay and low roughness. These good growth characteristics resulted in the excellent conformality for nanometer-scale vias and trenches. Additionally, AAO nanotemplates were fabricated directly on Si and Ti/Si substrates through a multiple anodization process. AAO nanotemplates with various hole sizes (30-100 nm) and aspect ratios (2:1-20:1) were fabricated by controlling the anodizing process parameters. The barrier layers between AAO nanotemplates and Si substrates were completely removed by reactive ion etching (RIE) using BCl(3) plasma. By combining the ALD Ru and the AAO nanotemplate, Ru nanostructures with controllable sizes and shapes were prepared on Si and Ti/Si substrates. The Ru nanowire array devices as a platform for sensor devices exhibited befitting properties of good ohmic contact and high surface/volume ratio. PMID:21817499

  15. Novel light-weight, high-performance anode-supported microtubular solid oxide fuel cells with an active anode functional layer

    Science.gov (United States)

    Liu, Tong; Wang, Yao; Ren, Cong; Fang, Shumin; Mao, Yating; Chen, Fanglin

    2015-10-01

    Influence of the air-gap, the distance from the tube-in-orifice spinneret to the upper surface of the external coagulant bath during the extrusion/phase-inversion process, on the microstructure of nickel - yttria-stabilized zirconia (Ni-YSZ) hollow fibers has been systematically studied. When the air-gap is 0 cm, the obtained Ni-YSZ hollow fiber has a sandwich microstructure. However, when the air-gap is increased to 15 cm, a bi-layer Ni-YSZ hollow fiber consisting of a thin layer with small pores and a thick support with highly porous fingerlike macrovoids has been achieved. The output power density of microtubular solid oxide fuel cells (MT-SOFCs) with a cell configuration of Ni-YSZ/YSZ/YSZ-LSM increases from 594 mW cm-2 for the cells with the Ni-YSZ anode of sandwich microstructure to 832 mW cm-2 for the cells with the Ni-YSZ anode of bi-layer microstructure at 750 °C, implying that to achieve the same output power density, the weight of the cells with the bi-layer anode support can be reduced to 41.5% compared with that of the cells with the sandwich anode support. Thermal-cycling test shows no obvious degradation on the open-circuit-voltage (OCV), indicating that the MT-SOFCs have robust resistance to thermal cycling.

  16. Possibilities of Increase of Adhesion of the Cubic Boron Nitride Coatings by Applying an Interfacial Layers

    Institute of Scientific and Technical Information of China (English)

    Maciej Kupczyk

    2004-01-01

    In the work the chosen investigations of the adhesion force of thin, superhard coatings to the cutting edges made of cemented carbides are presented. For identification of the adhesion force of coatings to substrate an automatic scratch tester constructed at Poznan University of Technology was applied. The estimation of the adhesion force (value of critical load measured during scratch test) was carried out on the base of the vibration signal. Results of investigations are pointed at the influence of a surface preparation (degreasing, etching, low and high-temperature sputtering) on a critical load values.It was found that the most effective method for surface preparation is low temperature sputtering. The influence of the TiC+Al2O3+TiN interfacial layer on increase of the adhesion force of BN coating to cemented carbides substrate was observed.

  17. SnO2 nanosheet as a photoanode interfacial layer for dyesensitized solar cells

    Institute of Scientific and Technical Information of China (English)

    CAI Feng-shi; WANG Jing; YUAN Zhi-hao; DUAN Yue-qin

    2011-01-01

    SnO2,nanosheet films about 200 nm in thickness are successfully fabricated on fluorine-doped tin oxide(FTO) glass by a facile solution-grown approach.The prepared SnO2 nanosheet film is applied as an interfacial layer between the nanocrystalline TiO2 film and the FTO substrate in dye-sensitized solar cells(DSCs).Experimental results show that the introduction of a SnO2 nanosheet film not only suppresses the electron back-transport reaction at the electrolyte/FTO interface but also provides an efficient electron transition channel along the SnO2 nanosheets,and as a result,increasing the open circuit voltage and short current density,and finally improving the conversion efficiency for the DSCs from 3.89% to 4.62%.

  18. Transient behavior of CO poisoning of the anode catalyst layer of a PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Chu, H.S.; Wang, C.P.; Liao, W.C. [Department of Mechanical Engineering, National Chiao Tung University, Hsinchu, Taiwan 300 (ROC); Yan, W.M. [Department of Mechatronic Engineering, Huafan University, Shih Ting, Taipei, Taiwan 223 (ROC)

    2006-09-22

    A one-dimensional transient mathematical model is applied to simulate the carbon monoxide poisoning effect on the performance of a PEM fuel cell. Based on the CO kinetic model developed by Springer et al. [T.E. Springer, T. Rockward, T.A. Zawodzinski, S. Gottesfeld, J. Electrochem. Soc. 148 (2001) A11-A23], the transient behaviors of the CO poisoning process across the anode catalyst layer is investigated. The results show that the hydrogen coverage, {theta}{sub H}, decreases with the time due to CO adsorption on the catalyst sites. A higher CO concentration results in fewer available catalyst sites for hydrogen electro-oxidation and a significant decrease in the response time to reach steady state, t{sub ss}. Increasing the anode overpotential and the gas porosity would result in an increase in the current density, especially at low levels of CO concentration. (author)

  19. Ultra-thin fluoropolymer buffer layer as an anode stabilizer of organic light emitting devices

    International Nuclear Information System (INIS)

    We have investigated the effect of thin fluoro-acrylic polymer as an anode stabilizer on the lifetime of an organic light emitting device (OLED). Surface chemical properties of commercial fluoropolymer, FC-722 (Fluorad(TM) of 3M), on indium-tin oxide (ITO) were characterized by x-ray photoemission spectroscopy. An OLED with 1 nm thick fluoropolymeric film showed identical brightness and efficiency behaviour and improved operational stability compared with the reference device with UV-O3 treated ITO. The improvement in the lifetime was accompanied by the suppression of the voltage increase at the initial stage of constant-current driving, which can be attributed to the action of the FC-722 layer by smoothing the ITO surface. Fluoropolymer coating, therefore, improves the lifetime of the small molecular OLED by the simple and reliable anode-stabilizing process

  20. Ultra-thin fluoropolymer buffer layer as an anode stabilizer of organic light emitting devices

    Science.gov (United States)

    Yang, Nam Chul; Lee, Jaeho; Song, Myung-Won; Ahn, Nari; Kim, Mu-Hyun; Lee, Songtaek; Doo Chin, Byung

    2007-08-01

    We have investigated the effect of thin fluoro-acrylic polymer as an anode stabilizer on the lifetime of an organic light emitting device (OLED). Surface chemical properties of commercial fluoropolymer, FC-722 (Fluorad™ of 3M), on indium-tin oxide (ITO) were characterized by x-ray photoemission spectroscopy. An OLED with 1 nm thick fluoropolymeric film showed identical brightness and efficiency behaviour and improved operational stability compared with the reference device with UV-O3 treated ITO. The improvement in the lifetime was accompanied by the suppression of the voltage increase at the initial stage of constant-current driving, which can be attributed to the action of the FC-722 layer by smoothing the ITO surface. Fluoropolymer coating, therefore, improves the lifetime of the small molecular OLED by the simple and reliable anode-stabilizing process.

  1. Interfacial instability induced by lateral vapor pressure fluctuation in bounded thin liquid-vapor layers

    CERN Document Server

    Kanatani, Kentaro

    2008-01-01

    We study an instability of thin liquid-vapor layers bounded by rigid parallel walls from both below and above. In this system, the interfacial instability is induced by lateral vapor pressure fluctuation, which is in turn attributed to the effect of phase change: evaporation occurs at the hotter portion of the interface and condensation at the colder one. The high vapor pressure drives the liquid away and the low one pulls it up. A set of equations describing the temporal evolution of the interface of the liquid-vapor layers is derived. This model neglects the effect of mass loss or gain at the interface and guarantees the mass conservation of the liquid layer. The result of linear stability analysis of the model shows that the presence of the pressure dependence of the local saturation temperature suppresses the growth of long-wave disturbances. We find the stability criterion, which suggests that only slight temperature gradients are sufficient to overcome the stabilizing gravitational effect for a water an...

  2. The role of interfacial water layer in atmospherically relevant charge separation

    Science.gov (United States)

    Bhattacharyya, Indrani

    Charge separation at interfaces is important in various atmospheric processes, such as thunderstorms, lightning, and sand storms. It also plays a key role in several industrial processes, including ink-jet printing and electrostatic separation. Surprisingly, little is known about the underlying physics of these charging phenomena. Since thin films of water are ubiquitous, they may play a role in these charge separation processes. This talk will focus on the experimental investigation of the role of a water adlayer in interfacial charging, with relevance to meteorologically important phenomena, such as atmospheric charging due to wave actions on oceans and sand storms. An ocean wave generates thousands of bubbles, which upon bursting produce numerous large jet droplets and small film droplets that are charged. In the 1960s, Blanchard showed that the jet droplets are positively charged. However, the charge on the film droplets was not known. We designed an experiment to exclusively measure the charge on film droplets generated by bubble bursting on pure water and aqueous salt solution surfaces. We measured their charge to be negative and proposed a model where a slight excess of hydroxide ions in the interfacial water layer is responsible for generating these negatively charged droplets. The findings from this research led to a better understanding of the ionic disposition at the air-water interface. Sand particles in a wind-blown sand layer, or 'saltation' layer, become charged due to collisions, so much so, that it can cause lightning. Silica, being hydrophilic, is coated with a water layer even under low-humidity conditions. To investigate the importance of this water adlayer in charging the silica surfaces, we performed experiments to measure the charge on silica surfaces due to contact and collision processes. In case of contact charging, the maximum charge separation occurred at an optimum relative humidity. On the contrary, in collisional charging process, no

  3. MoO3–Au composite interfacial layer for high efficiency and air-stable organic solar cells

    DEFF Research Database (Denmark)

    Pan, Hongbin; Zuo, Lijian; Fu, Weifei;

    2013-01-01

    investigated by atomic force microscopy (AFM) and showed that the originally rough ITO substrate became smooth after depositing the composite film, with the root mean square roughness (RMS) decreased from 4.08nm to 1.81nm. The smooth surface reduced the bias-dependent carrier recombination, resulting in a......Efficient and stable polymer bulk-heterojunction solar cells based on regioregular poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PC61BM) blend active layer have been fabricated with a MoO3–Au co-evaporation composite film as the anode interfacial layer (AIL). The optical...... large shunt resistance and thus improving the fill factor and efficiency of the devices. Additionally, the air stability of devices with different AILs (MoO3–Au composite, MoO3 and PEDOT:PSS) were studied and it was found that the MoO3–Au composite layer remarkably improved the stability of the solar...

  4. Selective modulation of charge-carrier transport of a photoanode in a photoelectrochemical cell by a graphitized fullerene interfacial layer

    NARCIS (Netherlands)

    Park, S.; Lim, D.C.; Hong, E.M.; Lee, J-Y.; Heo, J.; Lim, J.H.; Lee, C.-L.; Kim, K.; Mul, G.

    2015-01-01

    We show that a graphitic carbon interfacial layer, derived from C70 by annealing at 500 °C, results in a significant increase in the attainable photocurrent of a photoelectrochemical cell that contains a WO3-functionalized fluorine-doped tin oxide (FTO) photoanode. Time-resolved photoluminescence sp

  5. 石墨烯衍生物作为有机太阳能电池界面材料的研究进展∗%Recent progress in graphene and its derivatives as interfacial layers in organic solar cells

    Institute of Scientific and Technical Information of China (English)

    黄林泉; 周玲玉; 于为; 杨栋; 张坚; 李灿

    2015-01-01

    本文综述了石墨烯及其衍生物作为界面材料在有机太阳能电池中的应用,包括作为阳极界面层、阴极界面层和叠层电池中间层等方面。氧化石墨烯由于较好的透光性,易于分散在水溶液中与溶液加工等优点已被应用在有机太阳能电池中。对氧化石墨烯作为阳极界面层的研究包括通过部分还原或掺杂提高其导电性、通过引入高负电性原子提高其表面功函数,以及通过与其他材料复合提高性能等。同时,本文综述了石墨烯衍生物及复合材料作为有机太阳能电池阴极界面层和叠层电池中间层的研究。最后本文展望了石墨烯及其衍生物在有机太阳能电池与有机无机复合钙钛矿太阳能电池中的应用前景。%This review surveys the application of graphene and its derivatives in organic solar cells, used as interfacial layers:including anode interfacial layers, cathode interfacial layers, and intermediate layers in a tandem device. Research work has be done for increasing the electroconductivity by reducing the oxide to partially oxidized graphene, as well as chemically modifying or making composite interfacial layer. Additionally, the researches on graphene derivatives and combined interfacial layers used as a cathode interfacial layer or an intermediate layer in the tandem device are discussed. Finally, this review suggests that graphene and its derivatives are potential to be used in perovskite solar cells.

  6. Interfacial characteristics of HfO2 films grown on strained Si0.7Ge0.3 by atomic-layer deposition

    International Nuclear Information System (INIS)

    The interfacial characteristics of gate stack structure of HfO2 dielectrics on strained Si0.7Ge0.3 deposited by atomic-layer deposition were investigated. An interfacial layer including GeOx layers was grown on a SiGe substrate, and the thickness of the GeOx layer at the interfacial layer was decreased after the annealing treatment, while SiO2 layer was increased. The ∼50-A-thick HfO2 film with an amorphous structure was converted into a polycrystalline structure after rapid annealing at temperature of over 700 deg. C for 5 min. The interfacial silicate layer was effectively suppressed by GeOx formation, while the silicate layer was formed after the annealing treatment. GeOx formation in an as-grown film resulted in a decrease in the accumulation capacitance and an increase in the oxide trap charge

  7. Deposition of Hf-silicate gate dielectric on SixGe1-x(100): Detection of interfacial layer growth

    International Nuclear Information System (INIS)

    The deposition of a stable high-κ dielectric material such as hafnium silicate in direct contact with strained epitaxial SixGe1-x(100) layers on Si(100) provides the prospect of eliminating the Si buffer layer that is currently used to form the gate oxide in SiGe-based devices. In this study, ∼3-nm-thick hafnium silicate films were produced by sputter deposition of hafnium silicide films on precleaned SixGe1-x(100), with subsequent UV-O3 oxidation at room temperature. Prolonged UV-O3 exposure at room temperature leads to the growth of an interfacial layer comprised of a mixture of silicon and germanium oxides. We report on the use of x-ray photoelectron spectroscopy, particularly the x-ray excited Ge (L3MM) Auger feature to optimize UV-O3 exposure time, and minimize the interfacial layer growth of silicon and germanium oxides

  8. Effect of electrolyte temperature on the thickness of anodic aluminium oxide (AAO layer

    Directory of Open Access Journals (Sweden)

    P. Michal

    2016-07-01

    Full Text Available Effect of electrolyte temperature on the thickness of resulting oxide layer has been studied. Unlike previous published studies this article was aimed to monitor the relationship between electrolyte temperature and resulting AAO layer thickness in interaction with other input factors affecting during anodizing process under special process condition, i.e. lower concentration of sulphuric acid, oxalic acid, boric acid and sodium chloride. According to Design of Experiments (DOE 80 individual test runs of experiment were carried out. Using statistical analysis and artificial intelligence for evaluation, the computational model predicting the thickness of oxide layer in the range from 5 / μm to 15 / μm with tolerance ± 0,5 / μm was developed.

  9. Effect of bending on anodized Ti6Al4V alloy: I. Surface layers characteristics

    Directory of Open Access Journals (Sweden)

    A. Kierzkowska

    2006-08-01

    Full Text Available Purpose: The plastic deformation behaviour of the anodized binary titanium alloy Ti6Al4V was characterizedin mechanical and electrochemical tests.Design/methodology/approach: The effect of tensile and compressive stresses on properties of differentclinically relevant surfaces of the deformed by bending implant rods was investigated. The deformationbehaviour was characterized by FEM analysis. Relevant surfaces in tensile and compressive zones werecharacteristics by microhardness and roughness measurements, and electrochemical testing (Ecor, anodicpolarization, EIS in oxygen-saturated Ringer’s solution.Findings: It was concluded that bending influenced mostly the properties of material in the tensile zone of thespecimen, whereas the properties of surface layer in the compressive zone and the properties of surface layer intensile zone after rebending are comparable and not so severe.Research limitations/implications: Studies were performed in static conditions, fatique studies are planned inthe future.Practical implications: Results are of great importance in for surgical practice in the in the evaluation of theinfluence of shaping process applied during pre-operative procedures on the performance of spinal implantsystems.Originality/value: In the paper a typical pre-operative procedure of shaping was applied to anodized titaniumimplants in order to evaluate its influence on the characteristics of the surface layer. Studies were focused onthe safety their application in vivo.

  10. Nanoporous anodic titanium dioxide layers as potential drug delivery systems: Drug release kinetics and mechanism.

    Science.gov (United States)

    Jarosz, Magdalena; Pawlik, Anna; Szuwarzyński, Michał; Jaskuła, Marian; Sulka, Grzegorz D

    2016-07-01

    Nanoporous anodic titanium dioxide (ATO) layers on Ti foil were prepared via a three step anodization process in an electrolyte based on an ethylene glycol solution with fluoride ions. Some of the ATO samples were heat-treated in order to achieve two different crystallographic structures - anatase (400°C) and a mixture of anatase and rutile (600°C). The structural and morphological characterizations of ATO layers were performed using a field emission scanning electron microscope (SEM). The hydrophilicity of ATO layers was determined with contact angle measurements using distilled water. Ibuprofen and gentamicin were loaded effectively inside the ATO nanopores. Afterwards, an in vitro drug release was conducted for 24h under a static and dynamic flow conditions in a phosphate buffer solution at 37°C. The drug concentrations were determined using UV-Vis spectrophotometry. The absorbance of ibuprofen was measured directly at 222nm, whether gentamicin was determined as a complex with silver nanoparticles (Ag NPs) at 394nm. Both compounds exhibited long term release profiles, despite the ATO structure. A new release model, based on the desorption of the drug from the ATO top surface followed by the desorption and diffusion of the drug from the nanopores, was derived. The proposed release model was fitted to the experimental drug release profiles, and kinetic parameters were calculated. PMID:27037782

  11. Probing the Interfacial Interaction in Layered-Carbon-Stabilized Iron Oxide Nanostructures: A Soft X-ray Spectroscopic Study.

    Science.gov (United States)

    Zhang, Hui; Liu, Jinyin; Zhao, Guanqi; Gao, Yongjun; Tyliszczak, Tolek; Glans, Per-Anders; Guo, Jinghua; Ma, Ding; Sun, Xu-Hui; Zhong, Jun

    2015-04-22

    We have stabilized the iron oxide nanoparticles (NPs) of various sizes on layered carbon materials (Fe-oxide/C) that show excellent catalytic performance. From the characterization of X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES), scanning transmission X-ray microscopy (STXM) and X-ray magnetic circular dichroism spectroscopy (XMCD), a strong interfacial interaction in the Fe-oxide/C hybrids has been observed between the small iron oxide NPs and layered carbon in contrast to the weak interaction in the large iron oxide NPs. The interfacial interaction between the NPs and layered carbon is found to link with the improved catalytic performance. In addition, the Fe L-edge XMCD spectra show that the large iron oxide NPs are mainly γ-Fe2O3 with a strong ferromagnetic property, whereas the small iron oxide NPs with strong interfacial interaction are mainly α-Fe2O3 or amorphous Fe2O3 with a nonmagnetic property. The results strongly suggest that the interfacial interaction plays a key role for the catalytic performance, and the experimental findings may provide guidance toward rational design of high-performance catalysts. PMID:25839786

  12. Improved Performance of Organic Light-Emitting Diodes with MgF2 as the Anode Buffer Layer

    Institute of Scientific and Technical Information of China (English)

    XIE Jing; ZHANG De-Qiang; WANG Li-Duo; DUAN Lian; QIAO Juan; QIU Yong

    2006-01-01

    @@ Organic light-emitting diodes (OLEDs) based on N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB) and tris (8-hydroxyquinoline) aluminium (Alq3) are improved by using a thin MgF2 buffer layer sandwiched between the indium tin oxide (ITO) anode and hole transporting layer (HTL) of NPB.

  13. Electrical properties of LiNbO3 (electrolyte)/Cu (anode) bi-layers

    International Nuclear Information System (INIS)

    In this work specific film structures of Li-Nb-O/Li/Li-Nb-O are investigated by AC Impedance Spectroscopy measurements at different temperatures. This gives the opportunity to investigate properties of the material itself and, at the same time, to consider the influence of the grain boundaries on the ionic behavior of the polycrystalline Lithium Niobate. On the other hand, LiNbO3/Li/Cu multi-layers are studied as electrolyte/anode bi-layers and potential parts of 'Li-free' microbatteries. The Li deficiency in the as deposited Li-Nb-O films is cured by forming a 'sandwich' of Li-Nb-O/Li/Li-Nb-O, which after annealing becomes ionic conductor. The electrical behavior of an annealed film depends on two sources. The first is due to properties of the material itself and the second is based on the network of the grain boundaries. The average size of the grains is strongly influenced by the structure of the ohmic-contact/substrate. The electrical behavior of the electrolyte/anode interface of the 'Li-free' structure LiNbO3/Li/Cu/Au is very similar to the impedance measurements of the single LiNbO3 single films. The whole multilayer structure, though, presents a third relaxation time which is consistent of a small resistance. This resistance is independent of temperature and it seems that is due to the metallic interface Li/Cu/Au.

  14. Stability of High Band Gap P3HT : PCBM Organic Solar Cells Using TiOx Interfacial Layer

    Directory of Open Access Journals (Sweden)

    Kurniawan Foe

    2014-01-01

    Full Text Available We fabricated a poly[3-hexylthiophene] (P3HT and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM organic photovoltaic cells (OPCs using TiOx interfacial layer. We performed optimization processes for P3HT : PC61BM with the TiOx layer. We found that a solution based TiOx layer coated at a spin speed of 3000 rpm improved the photon absorption of the active layer. An optimized TiOx layer was also used as the interfacial layer to investigate the stability of P3HT : PC61BM OPC. After 70 days of storage, we observed that the short-circuit current density (JSC dropped by 16.2%, fill factor (FF dropped by 10.6%, and power conversion efficiency (PCE dropped approximately by 25%, while the open-circuit voltage (VOC remained relatively stable. We found that a solution based TiOx layer synthesized using a sol-gel chemistry method was very effective in protecting the active layer from degradation.

  15. Barrier layer non-uniformity effects in anodized aluminum oxide nanopores on ITO substrates

    International Nuclear Information System (INIS)

    Nanoporous anodic aluminum oxide (AAO) has been used widely as a template for device fabrication. In many nanostructured electro-optical device designs, AAO grown on an ITO substrate is the desired configuration. However, a residual thin aluminum oxide barrier layer between ITO and the AAO pores remains and process non-uniformities during the template fabrication can cause serious problems in the quality of nanowires deposited later in these pores. It was observed that in many templates, even the pores closest to each other could have their barrier layer thicknesses differ by as much as 10-20 nm. In this paper, causes and remedies for this non-uniformity are investigated, including the effects of a thin Ti interlayer inserted between the ITO and AAO. Templates with different Ti layer thickness and annealing conditions were compared. Mechanisms for the formation of voids beneath the barrier layer were analyzed and studied experimentally. Reactive ion etch (RIE) was found to be the preferred method to mitigate process non-uniformities. Using the above methods, barrier-free AAO templates on ITO substrates were obtained; their thicknesses ranged from 200 to 1000 nm. The characteristics of CdS nanowires electrodeposited into the initial templates with non-uniform barrier layer thicknesses and into the processed, barrier-free templates were compared.

  16. Direct anodic growth of thick WO3 mesosponge layers and characterization of their photoelectrochemical response

    International Nuclear Information System (INIS)

    Thick mesoporous tungsten oxide (WO3) layers can be formed by anodization of tungsten in a 10 wt% K2HPO4/glycerol electrolyte, if the electrolyte temperature is around 80-100 oC. At 90 oC, a regular mesoporous WO3 layer was grown up to a thickness of approximately 9 μm. This WO3 mesosponge layer consists of typical feature sizes of 20-30 nm and pore widths of 10-30 nm. The photoresponse of different layer thicknesses and different annealing treatments was characterized in a photoelectrochemical cell. The highest photocurrents were observed with a 2.5 μm thick WO3 layer annealed at 550 oC consisting of a mixture of orthorhombic, triclinic and monoclinic phases. Incident photon to current efficiencies (IPCEs) of the samples were 73.4% in a 1 M HClO4 electrolyte and 167.5% for methanol photo-oxidation in 0.1 M CH3OH/1 M HClO4 electrolyte, at 1 V vs. Ag/AgCl under illumination at a wavelength of 420 nm.

  17. Improvement in Mobility and Stability of n-Type Organic Field-Effect Transistors with a Hole Transporting Interfacial Layer

    Science.gov (United States)

    Nakayama, Ken-ichi; Ishikawa, Motomi; Yokoyama, Masaaki

    2009-02-01

    Field-effect electron mobility and stability of N,N'-dioctyl-3,4,9,10-perylene tetracarboxylic diimide (PTCDI-C8H) improved when a hole-transporting layer, used in organic light-emitting diodes, was inserted between the gate insulator and the channel layer. This result suggests that insertion of an electronically active interfacial layer of an organic semiconductor is more effective in eliminating electron traps of the insulator surface compared to conventional surface treatment to obtain an inert surface.

  18. Ultimate Scaling of High-κ Gate Dielectrics: Higher-κ or Interfacial Layer Scavenging?

    Directory of Open Access Journals (Sweden)

    Takashi Ando

    2012-03-01

    Full Text Available Current status and challenges of aggressive equivalent-oxide-thickness (EOT scaling of high-κ gate dielectrics via higher-κ ( > 20 materials and interfacial layer (IL scavenging techniques are reviewed. La-based higher-κ materials show aggressive EOT scaling (0.5–0.8 nm, but with effective workfunction (EWF values suitable only for n-type field-effect-transistor (FET. Further exploration for p-type FET-compatible higher-κ materials is needed. Meanwhile, IL scavenging is a promising approach to extend Hf-based high-κ dielectrics to future nodes. Remote IL scavenging techniques enable EOT scaling below 0.5 nm. Mobility-EOT trends in the literature suggest that short-channel performance improvement is attainable with aggressive EOT scaling via IL scavenging or La-silicate formation. However, extreme IL scaling (e.g., zero-IL is accompanied by loss of EWF control and with severe penalty in reliability. Therefore, highly precise IL thickness control in an ultra-thin IL regime ( < 0.5 nm will be the key technology to satisfy both performance and reliability requirements for future CMOS devices.

  19. Synthesis of exfoliated PA66 nanocomposites via interfacial polycondensation: effect of layered silicate and silica nanoparticles

    Indian Academy of Sciences (India)

    HOSSIEN GHARABAGHI; MEHDI RAFIZADEH; FARAMARZ AFSHAR TAROMI

    2016-08-01

    Nanocomposites of polyamide 66 (PA66) with layered silicate and silica (SiO2) nanoparticles were prepared via in situ interfacial polycondensation method. Hexamethylenediamine (HDMA) and adipoyl chloride(AdCl) were reacted in a two-phase media. Montmorillonite (NaMMT) and silica nanoparticles were added to reacting media. Preparation of PA66 and its nanocomposites were studied using Fourier transform infrared spectroscopy.Dispersion of nanoparticles was studied using X-ray diffraction and transmission electron microscopy. The results show that two structures were achieved using two kinds of nanoparticles. Silica nanoparticles were partially exfoliated, while NaMMT nanoparticles were hybrid intercalated–exfoliated in nanocomposite samples. Thermal properties of samples were investigated by differential scanning calorimetry. The results suggest that crystallinity is heterogeneous in the presence of nanoparticles. Kinetic of crystallization was studied by means of Avrami equation, based on the kinetic parameters, spherulites are produced. Results were reported for nanocomposites containing 2 and 4% of nanoparticles. Avrami equation parameter, n, shows that spherulite crystallization occured in the samples. Addition of nanoparticles decreases n first, then n increases with nanoparticle content.

  20. Manipulation of interfacial instabilities by using a soft, deformable solid layer

    Indian Academy of Sciences (India)

    Gaurav; V Shankar

    2015-05-01

    Multilayer flows are oftensusceptible to interfacial instabilities caused due to jump in viscosity/elasticity across thefluid–fluid interface. It is frequently required to manipulate and control these interfacial instabilities in various applications such as coating processes or polymer coextrusion. We demonstrate here the possibility of using a deformable solid coating to control such interfacial instabilities for various flow configurations and for different fluid rheological behaviors. In particular, we show complete suppression of interfacial flow instabilities by making the walls sufficiently deformable when the configuration was otherwise unstable for the case of flow past a rigid surface. While these interfacial instabilities could be suppressed in certain parameter regimes, it is also possible to enhance the flow instabilities by tuning the shear modulus of the deformable solid coating for other ranges of parameters.

  1. Porous anodic alumina on galvanically grown PtSi layer for application in template-assisted Si nanowire growth

    Directory of Open Access Journals (Sweden)

    Stavrinidou Eleni

    2011-01-01

    Full Text Available Abstract We report on the fabrication and morphology/structural characterization of a porous anodic alumina (PAA/PtSi nano-template for use as matrix in template-assisted Si nanowire growth on a Si substrate. The PtSi layer was formed by electroless deposition from an aqueous solution containing the metal salt and HF, while the PAA membrane by anodizing an Al film deposited on the PtSi layer. The morphology and structure of the PtSi layer and of the alumina membrane on top were studied by Scanning and High Resolution Transmission Electron Microscopies (SEM, HRTEM. Cross sectional HRTEM images combined with electron diffraction (ED were used to characterize the different interfaces between Si, PtSi and porous anodic alumina.

  2. Morphology control of anodic ZrO2 layer for the prevention of H2 production from Zr-4 cladding

    Energy Technology Data Exchange (ETDEWEB)

    Park, Y. J.; Park, J. W.; Cho, S. O. [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2014-05-15

    Since the Fukushima disaster happened, studies on accident-resistant nuclear fuel has been carried out actively. There has been an attempt to protect zircaloy fuel cladding by coating SiC. Research on producing oxide layer that can block fuel cladding from water on the surface of zircaloy fuel cladding by means of anodizing to reduce the rate of oxidation of fuel cladding at Loss Of Coolant Accident (LOCA) is an significant ongoing study subject. Applying nanostructured oxide layer to the prevention of thermal deformation of oxide layer was already suggested in our research group, the reasons of which is nanoporous structure is better than nanotube structure in terms of corrosion-resistant structure because nanotube structure can be easily peeled off. In this study, methods which are able to control morphology between nanoporous and nanotube structure were conducted by changing the anodizing conditions. Hence, Using glycerol and ammonium fluoride, Zircaloy-4 was anodized by varying water contents and applied voltage. It reveals that the alloy transition from nanoporous structure to nanotube structure can be changed by varying water contents of anodizing solution and applied voltage. Anodizing conditions determining nanoporous structure were obtained. According to the mechanism already suggested, nanoporous oxide layer that can seal the fuel cladding perfectly, and increase critical heat flux (CHF) due to large surface area is easily produced. This results obtained in this paper expected to be facilitated fabrication of accident-resistant nuclear fuel cladding.

  3. The effect of anodization parameters on the formation of nanoporous TiO{sub 2} layers and their photocatalytic activities

    Energy Technology Data Exchange (ETDEWEB)

    Erol, Mustafa, E-mail: m.erol@deu.edu.tr [Dokuz Eylul University, Department of Metallurgical and Materials Engineering, Buca 35160, Izmir (Turkey); Dokuz Eylul University, The Graduate School of Natural and Applied Sciences, Buca 35160, Izmir (Turkey); Hitit University, Department of Metallurgical and Materials Engineering, 19000 Çorum (Turkey); Dikici, Tuncay [Dokuz Eylul University, Department of Metallurgical and Materials Engineering, Buca 35160, Izmir (Turkey); Dokuz Eylul University, The Graduate School of Natural and Applied Sciences, Buca 35160, Izmir (Turkey); Izmir Katip Celebi University, Department of Materials Science and Engineering, Cigli 35620, Izmir (Turkey); Toparli, Mustafa; Celik, Erdal [Dokuz Eylul University, Department of Metallurgical and Materials Engineering, Buca 35160, Izmir (Turkey); Dokuz Eylul University, Center for Fabrication and Applications of Electronic Materials (EMUM), Buca 35160, Izmir (Turkey); Dokuz Eylul University, Department of Nanoscience and Nanoengineering, Buca 35160, Izmir (Turkey)

    2014-08-01

    Highlights: • Nanoporous TiO{sub 2} layers were formed on titanium surfaces by anodization. • Effects of such parameters as voltage, temperature and time investigated in details. • 20 °C, 30–40 volts and 240 minutes were determined as the optimum parameters. - Abstract: In this work, nanoporous titanium dioxide (TiO{sub 2}) layers were successfully formed by electrochemical anodization method on titanium (Ti) surface in fluorine containing electrolytes with different processing parameters. The effects of anodization voltages, electrolyte temperature and anodization time on the microstructure and photocatalytic performance of nanoporous TiO{sub 2} layers were investigated and compared in details. Nanoporous structures were annealed at 480 °C for 2 h in air in order to obtain anatase transformation and increase crystallinity. The phase structure and surface morphology of the samples characterized by means of X-ray diffraction (XRD) and scanning electron microscope (SEM) respectively. The photocatalytic activity tests of the samples were evaluated by the degradation of aqueous methylene blue (MB) solutions under UV light illumination for different periods of time. The results showed that the processing parameters on production of nanoporous TiO{sub 2} layers played important roles in the degradation of aqueous MB solutions. To sum up, the highest photocatalytical activity was obtained at the sample anodized under 30 V for 30 min at 20 °C among the samples.

  4. Improvement in the breakdown endurance of high-κ dielectric by utilizing stacking technology and adding sufficient interfacial layer

    Science.gov (United States)

    2014-01-01

    Improvement in the time-zero dielectric breakdown (TZDB) endurance of metal-oxide-semiconductor (MOS) capacitor with stacking structure of Al/HfO2/SiO2/Si is demonstrated in this work. The misalignment of the conduction paths between two stacking layers is believed to be effective to increase the breakdown field of the devices. Meanwhile, the resistance of the dielectric after breakdown for device with stacking structure would be less than that of without stacking structure due to a higher breakdown field and larger breakdown power. In addition, the role of interfacial layer (IL) in the control of the interface trap density (Dit) and device reliability is also analyzed. Device with a thicker IL introduces a higher breakdown field and also a lower Dit. High-resolution transmission electron microscopy (HRTEM) of the samples with different IL thicknesses is provided to confirm that IL is needed for good interfacial property. PMID:25246869

  5. Effects of image charges, interfacial charge discreteness, and surface roughness on the zeta potential of spherical electric double layers

    OpenAIRE

    Gan, Zecheng; Xing, Xiangjun; Xu, Zhenli

    2012-01-01

    We investigate the effects of image charges, interfacial charge discreteness, and surface roughness on spherical electric double layers in electrolyte solutions with divalent counter-ions in the setting of the primitive model. By using Monte Carlo simulations and the image charge method, the zeta potential profile and the integrated charge distribution function are computed for varying surface charge strengths and salt concentrations. Systematic comparisons were carried out between three dist...

  6. Distinction between interfacial layer effect and trap passivation effect of N2 plasma treatment on LTPS-TFTs

    Science.gov (United States)

    Ma, William Cheng-Yu

    2014-10-01

    In this paper, N2 plasma surface treatment on high performance low-temperature poly-Si thin-film transistors (LTPS-TFTs) with HfO2 gate dielectric is demonstrated. A significant performance improvement by N2 plasma surface treatment is observed, including the threshold voltage VTH reduction ∼ -0.94 V, subthreshold swing S.S. improvement from 0.227 V/dec. to 0.188 V/dec., field effect mobility μFE enhancement ∼ +61% and driving current Idrv enhancement ∼ +95%. The individual impacts of interfacial layer growth effect and trap passivation effect of poly-Si channel film are investigated by the plasma induced interfacial layer (PIL) removal process. The results show that the PIL growth effect has more contribution to the improvement of VTH reduction and Idrv enhancement than the trap passivation effect of poly-Si channel film. Consequently, the interfacial layer engineering would be very important for the development of high performance LTPS-TFTs.

  7. Lubricating layer formed on porous anodic alumina template due to pore effect at water lubricated sliding and its properties

    International Nuclear Information System (INIS)

    A porous anodic alumina (PAA) template was manufactured to investigate the pore effect on the formation of lubricating layers. A PAA template with 260 nm pores was manufactured by two-step anodization using phosphoric acid. A sliding wear test was carried out using a ball-on-disk tester. Due to the pore effect, an aluminum hydroxide film; i.e., the lubricating layer, was formed at a specific condition. The PAA template has a low friction regime because of the aluminum hydroxide film. The adhesion and friction forces of the aluminum hydroxide film were measured using atomic force microscopy (AFM), and the adhesion and friction forces of the lubricating layer were lower than that of a typical oxide layer. Using AFM analysis, the existence of a lubricating layer can be verified.

  8. Enhancing the platinum atomic layer deposition infiltration depth inside anodic alumina nanoporous membrane

    International Nuclear Information System (INIS)

    Nanoporous platinum membranes can be straightforwardly fabricated by forming a Pt coating inside the nanopores of anodic alumina membranes (AAO) using atomic layer deposition (ALD). However, the high-aspect-ratio of AAO makes Pt ALD very challenging. By tuning the process deposition temperature and precursor exposure time, enhanced infiltration depth along with conformal coating was achieved for Pt ALD inside the AAO templates. Cross-sectional scanning electron microscopy/energy dispersive x-ray spectroscopy and small angle neutron scattering were employed to analyze the Pt coverage and thickness inside the AAO nanopores. Additionally, one application of platinum-coated membrane was demonstrated by creating a high-density protein-functionalized interface

  9. Enhancing the platinum atomic layer deposition infiltration depth inside anodic alumina nanoporous membrane

    Energy Technology Data Exchange (ETDEWEB)

    Vaish, Amit, E-mail: anv@udel.edu; Krueger, Susan; Dimitriou, Michael; Majkrzak, Charles [National Institute of Standards and Technology (NIST) Center for Neutron Research, Gaithersburg, MD 20899-8313 (United States); Vanderah, David J. [Institute for Bioscience and Biotechnology Research, NIST, Rockville, Maryland 20850 (United States); Chen, Lei, E-mail: lei.chen@nist.gov [NIST Center for Nanoscale Science and Technology, Gaithersburg, Maryland 20899-8313 (United States); Gawrisch, Klaus [Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892 (United States)

    2015-01-15

    Nanoporous platinum membranes can be straightforwardly fabricated by forming a Pt coating inside the nanopores of anodic alumina membranes (AAO) using atomic layer deposition (ALD). However, the high-aspect-ratio of AAO makes Pt ALD very challenging. By tuning the process deposition temperature and precursor exposure time, enhanced infiltration depth along with conformal coating was achieved for Pt ALD inside the AAO templates. Cross-sectional scanning electron microscopy/energy dispersive x-ray spectroscopy and small angle neutron scattering were employed to analyze the Pt coverage and thickness inside the AAO nanopores. Additionally, one application of platinum-coated membrane was demonstrated by creating a high-density protein-functionalized interface.

  10. Titanium oxide layers on aluminium substrates produced by the anodic spark deposition process

    International Nuclear Information System (INIS)

    Titanium oxide layers were prepared on pure aluminium substrates by the anodic spark deposition method. The formed crystalline titania (TiO2) phases rutile and anatase and the sodium titanium oxide (Na0.23TiO2) were identified. The corresponding crystallite size values were obtained from X-ray diffraction data by means of the Rietveld method. The crystallite size of each of these phases continuously increases with rising current density. Furthermore, the two-dimensional distribution of the titania phases on the sample surface was determined by Raman spectroscopy. It was found that the rutile/anatase ratio is inhomogeneous distributed on an observed area of 400 x 400 μm2.

  11. Anodic-spark layers on aluminium and titanium alloys in electrolytes with sodium tungstophosphate

    International Nuclear Information System (INIS)

    Influence of pH value of Na2H[PW12O40] aqueous 0.0083 M solution on the composition and morphology of anodic coatings on aluminium and titanium alloys formed galvanostatically under sparkling and breakdown voltage was studied using data of electron microscopy, elementary and X-ray phase analyses. It was ascertained that in low-acid, neutral and low-alkaline electrolytes multilayer coatings are formed, which contain in their outer layer oxides of elements making up the ligand sphere of heteropolyanions. In solutions featuring higher acidity and alkalinity the content of heteropolyanion components in the coatings decreases. By and large, the coating composition reflects the dependence of heteropolyanions composition in aqueous solution on pH value

  12. Third-order Stokes wave solutions for interfacial internal waves in a three-layer density-stratified fluid

    Institute of Scientific and Technical Information of China (English)

    Chen Xiao-Gang; Guo Zhi-Ping; Song Jin-Bao; He Xiao-Dong; Guo Jun-Ming; Bao Shu-Hong; Cui Wei

    2009-01-01

    Interfacial internal waves in a three-layer density-stratified fluid are investigated using a singular perturbation method, and third-order asymptotic solutions of the velocity potentials and third-order Stokes wave solutions of the associated elevations of the interracial waves are presented based on the small amplitude wave theory. As expected, the third-order solutions describe the third-order nonlinear modification and the third-order nonlinear interactions between the interracial waves. The wave velocity depends on not only the wave number and the depth of each layer but also on the wave amplitude.

  13. Influence on interfacial diffusive scatterings of the angle between the magnetizations of the two magnetic layers in a magnetic trilayer

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S.-P. [Department of Applied Physics, National Chia Yi University, 600 Chia Yi, Taiwan (China); Chang, C.-R. [Department of Physics, National Taiwan University, 10617 Taipei, Taiwan (China)]. E-mail: crchang@phys.ntu.edu.tw; Lai, C.-H. [Department of Materials Science and Engineering, National Tsing Hua University, 300 Hsinchu, Taiwan (China)

    2007-03-15

    To understand the influence of the relative angle between the magnetizations of the two magnetic layers in a magnetic trilayer on diffusive scatterings of a transport electron, we study an A-B-C magnetic trilayer by use of the effective mean-free-path model. Our theoretical results indicate that varying the relative angle can enhance or suppress an interfacial diffusive scattering on a transport spin-dependent electron if the thickness of the metallic layer is smaller than the spin relaxation length.

  14. Influence on interfacial diffusive scatterings of the angle between the magnetizations of the two magnetic layers in a magnetic trilayer

    International Nuclear Information System (INIS)

    To understand the influence of the relative angle between the magnetizations of the two magnetic layers in a magnetic trilayer on diffusive scatterings of a transport electron, we study an A-B-C magnetic trilayer by use of the effective mean-free-path model. Our theoretical results indicate that varying the relative angle can enhance or suppress an interfacial diffusive scattering on a transport spin-dependent electron if the thickness of the metallic layer is smaller than the spin relaxation length

  15. Simple solution-processed CuO{sub X} as anode buffer layer for efficient organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Wenfei [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Institute of Hybrid Materials, The Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Yang, Chunpeng [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Bao, Xichang, E-mail: baoxc@qibebt.ac.cn [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Sun, Liang; Wang, Ning [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Tang, Jianguo [Institute of Hybrid Materials, The Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Chen, Weichao [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Yang, Renqiang, E-mail: yangrq@qibebt.ac.cn [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China)

    2015-10-15

    Graphical abstract: - Highlights: • Simple solution-processed CuO{sub X} hole transport layer for efficient organic solar cell. • Good photovoltaic performances as hole transport layer in OSCs with P3HT and PBDTTT-C as donor materials. • The device with CuO{sub X} as hole transport layer shows great improved stability compared with that of device with PEDOT:PSS as hole transport layer. - Abstract: A simple, solution-processed ultrathin CuO{sub X} anode buffer layer was fabricated for high performance organic solar cells (OSCs). XPS measurement demonstrated that the CuO{sub X} was the composite of CuO and Cu{sub 2}O. The CuO{sub X} modified ITO glass exhibit a better surface contact with the active layer. The photovoltaic performance of the devices with CuO{sub X} layer was optimized by varying the thickness of CuO{sub X} films through changing solution concentration. With P3HT:PC{sub 61}BM as the active layer, we demonstrated an enhanced PCE of 4.14% with CuO{sub X} anode buffer layer, compared with that of PEDOT:PSS layer. The CuO{sub X} layer also exhibits efficient photovoltaic performance in devices with PBDTTT-C:PC{sub 71}BM as the active layer. The long-term stability of CuO{sub X} device is better than that of PEDOT:PSS device. The results indicate that the easy solution-processed CuO{sub X} film can act as an efficient anode buffer layer for high-efficiency OSCs.

  16. Analysis on interfacial layer of aluminum alloy and non-coated stainless steel joint made by TIG welding-brazing

    Institute of Scientific and Technical Information of China (English)

    Song Jiaaling; Lin Sanbao; Yang Chunli; Ma Guangchao; Wang Yinjie

    2009-01-01

    Dissimilar metals TIG welding-brazing of aluminum alloy and non-coated stainless steel was investigated. The resultant joint was characterized in order to identify the phases and the brittle intermetaUic compounds (IMCs) in the interfacial layer by optical metalloscope (OM), wanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), and the cracked joint was analyzed in order to understand the cracking mechanism of the joint. The results show that the microfusion of the stainless steel can improve the wetting and spreading of liquid aluminum base filler metal on the steel surface and the melted steel accelerates the formation of mass of brittle IMCs in the interracial layer, which causes the joint cracking badly. The whole interfacial layer is 5 - 7 μm thick and comprises approximately 5 μm-thickness reaction layer in aluminum side and about 2 μm-thickness diffusion layer in steel side. The stable Al-rich IMCs are formed in the interfaciallayer and the phases transfer from (Al + FeAl3) in aluminum side to (FeAl3+ Fe2Al5) and (α-Fe + FeAl) in steel side.

  17. Influence of the anodic etching current density on the morphology of the porous SiC layer

    Directory of Open Access Journals (Sweden)

    Anh Tuan Cao

    2014-03-01

    Full Text Available In this report, we fabricated a porous layer in amorphous SiC thin films by using constant-current anodic etching in an electrolyte of aqueous diluted hydrofluoric acid. The morphology of the porous amorphous SiC layer changed as the anodic current density changed: At low current density, the porous layer had a low pore density and consisted of small pores that branched downward. At moderate current density, the pore size and depth increased, and the pores grew perpendicular to the surface, creating a columnar pore structure. At high current density, the porous structure remained perpendicular, the pore size increased, and the pore depth decreased. We explained the changes in pore size and depth at high current density by the growth of a silicon oxide layer during etching at the tips of the pores.

  18. Improvement of interfacial adhesion in vertical GaN-based LEDs by introducing O2 plasma cleaning and intermediate layers

    International Nuclear Information System (INIS)

    Interfacial adhesion between an indium tin oxide (ITO)/Ni/Ag/Ni/Au p-electrode, and Au and Ni/Au seeds in vertical GaN-based light emitting diodes (LEDs) was enhanced by O2 plasma cleaning treatment of the Au surface in the p-electrode. However, AES and REELS analyses of the Au surface in the p-electrode detected surface damage to the p-electrode and photoresist (PR) passivation structure from O2 plasma cleaning. W/Ni and Al/Ni adhesion layers were introduced in the Au seed to increase interfacial adhesion between Au seed and untreated PR passivation. Forward leakage current as low as 0.91 nA at 2 V was observed for the vertical LED with the Al/Ni/Au seed, for which adhesion strength to O2 plasma-cleaned Au and untreated PR was 141.2 MPa and 62.8 MPa, respectively.

  19. Improvement of interfacial adhesion in vertical GaN-based LEDs by introducing O 2 plasma cleaning and intermediate layers

    Science.gov (United States)

    Kim, Sunjung

    2010-04-01

    Interfacial adhesion between an indium tin oxide (ITO)/Ni/Ag/Ni/Au p-electrode, and Au and Ni/Au seeds in vertical GaN-based light emitting diodes (LEDs) was enhanced by O 2 plasma cleaning treatment of the Au surface in the p-electrode. However, AES and REELS analyses of the Au surface in the p-electrode detected surface damage to the p-electrode and photoresist (PR) passivation structure from O 2 plasma cleaning. W/Ni and Al/Ni adhesion layers were introduced in the Au seed to increase interfacial adhesion between Au seed and untreated PR passivation. Forward leakage current as low as 0.91 nA at 2 V was observed for the vertical LED with the Al/Ni/Au seed, for which adhesion strength to O 2 plasma-cleaned Au and untreated PR was 141.2 MPa and 62.8 MPa, respectively.

  20. Controlling Interfacial Reactions and Intermetallic Compound Growth at the Interface of a Lead-free Solder Joint with Layer-by-Layer Transferred Graphene.

    Science.gov (United States)

    Ko, Yong-Ho; Lee, Jong-Dae; Yoon, Taeshik; Lee, Chang-Woo; Kim, Taek-Soo

    2016-03-01

    The immoderate growth of intermetallic compounds (IMCs) formed at the interface of a solder metal and the substrate during soldering can degrade the mechanical properties and reliability of a solder joint in electronic packaging. Therefore, it is critical to control IMC growth at the solder joints between the solder and the substrate. In this study, we investigated the control of interfacial reactions and IMC growth by the layer-by-layer transfer of graphene during the reflow process at the interface between Sn-3.0Ag-0.5Cu (in wt %) lead-free solder and Cu. As the number of graphene layers transferred onto the surface of the Cu substrate increased, the thickness of the total IMC (Cu6Sn5 and Cu3Sn) layer decreased. After 10 repetitions of the reflow process for 50 s above 217 °C, the melting temperature of Sn-3.0Ag-0.5Cu, with a peak temperature of 250 °C, the increase in thickness of the total IMC layer at the interface with multiple layers of graphene was decreased by more than 20% compared to that at the interface of bare Cu without graphene. Furthermore, the average diameter of the Cu6Sn5 scallops at the interface with multiple layers of graphene was smaller than that at the interface without graphene. Despite 10 repetitions of the reflow process, the growth of Cu3Sn at the interface with multiple layers of graphene was suppressed by more than 20% compared with that at the interface without graphene. The multiple layers of graphene at the interface between the solder metal and the Cu substrate hindered the diffusion of Cu atoms from the Cu substrate and suppressed the reactions between Cu and Sn in the solder. Thus, the multiple layers of graphene transferred at the interface between dissimilar metals can control the interfacial reaction and IMC growth occurring at the joining interface. PMID:26856638

  1. Poly (3,4-ethylenedioxythiophene) promotes direct electron transfer at the interface between Shewanella loihica and the anode in a microbial fuel cell

    Science.gov (United States)

    Liu, Xing; Wu, Wenguo; Gu, Zhongze

    2015-03-01

    Anode modification is an effective method for enhancing extracellular electron transportation and improving the power density of microbial fuel cells (MFCs). In this study, a new conductive polymer called poly (3,4-ethylenedioxythiophene) (PEDOT) is electrochemically polymerized to modify the anode. The surface of the electrochemically polymerized PEDOT layer has a widespread porous structure. Both the anode electrochemical discharge experiment and MFC discharge test demonstrate the improved performance of the PEDOT-modified anode compared with a plain anode. Cyclic voltammetry and electrochemical impedance spectroscopy analyses show that the PEDOT modification increases the availability of redox active sites and reduces the interfacial electron transfer resistance of the anode. Compared with the unmodified anode, the PEDOT anodic modification improves the power density by 43%-140 mW m-2. Possible mechanisms are proposed to help understand the function of the PEDOT-modified anodic layer.

  2. Formation of Diffusion Layers by Anode Plasma Electrolytic Nitrocarburizing of Low-Carbon Steel

    Science.gov (United States)

    Kusmanov, S. A.; Kusmanova, Yu. V.; Naumov, A. R.; Belkin, P. N.

    2015-08-01

    The structure of the low-carbon steel after plasma electrolytic nitrocarburizing in the electrolyte containing acetonitrile was investigated. The cross-sectional microstructure, composition, and phase constituents of a modified layer under different processing conditions were characterized. It is shown that the electrolyte that contained ammonium chloride and acetonitrile provides the saturation of steel with nitrogen and carbon and the formation of the Fe4N and FeN0.05 nitrides, Fe4C carbide and other phases. The nitrogen diffusion decreases the austenitization temperature and results in the formation of martensite after the sample cooling in the electrolyte. The formation of a carbon and nitrogen source in a vapor-gas envelope (VGE) is investigated. The proposed mechanism includes evaporation of acetonitrile in the VGE, its adsorption on an anode with the following thermal decomposition, and also the acetonitrile reduction to amine with subsequent hydrolysis to ethanol that is determined with the use of chromatographic method. The aqueous solution that contained 10 wt.% NH4Cl and 10 wt.% CH3CN allows one to obtain the nitrocarburized layer with the thickness of 0.22 mm and microhardness up to 740 HV during 10 min at 850 °C. This treatment regime leads to the decrease in the surface roughness of steel R a from 1.01 μm to 0.17 μm.

  3. Fabrication of super slippery sheet-layered and porous anodic aluminium oxide surfaces and its anticorrosion property

    Science.gov (United States)

    Song, Tingting; Liu, Qi; Liu, Jingyuan; Yang, Wanlu; Chen, Rongrong; Jing, Xiaoyan; Takahashi, Kazunobu; Wang, Jun

    2015-11-01

    Inspired by natural plants such as Nepenthes pitcher plants, super slippery surfaces have been developed to improve the attributes of repellent surfaces. In this report, super slippery porous anodic aluminium oxide (AAO) surfaces have fabricated by a simple and reproducible method. Firstly, the aluminium substrates were treated by an anodic process producing micro-nano structured sheet-layered pores, and then immersed in Methyl Silicone Oil, Fluororalkylsilane (FAS) and DuPont Krytox, respectively, generating super slippery surfaces. Such a good material with excellent anti-corrosion property through a simple and repeatable method may be potential candidates for metallic application in anti-corrosion and extreme environment.

  4. Nano Ru Impregnated Ni-YSZ Anode as Carbon Resistance Layer for Direct Ethanol Solid Oxide Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    SUN Liangliang; ZHENG Tao; HU Zhimin; LUO Linghong; WU Yefan; XU Xu; CHENG Liang; SHI Jijun

    2015-01-01

    Carbon formation on conventional Ni and Y2O3stabilized zirconia (Ni/YSZ) anodes is a major problem for direct ethanol solid oxide fuel cells (DE-SOFC). A nanostructure Ru layer was grown in Ni/YSZ anodes through wet impregnation method with RuCl3solvent at pH=4. Anode-supported Ni-YSZ/YSZ/(La0.8Sr0.2)0.98MnO3±δ(LSM) and Ru-Ni-YSZ/YSZ/LSM fuel cells were compared in terms of the performance and carbon formation with ethanol fuel. X-ray diffraction, scanning electron microscopy,energy disperse spectroscopy and electrochemical workstation were used to study the morphology and fuel cell performance. The results indicate that a nano structured and pearl like Ru layer was well dispersed on the surface of Ni-YSZ materials. The single cell with Ru-impregnated Ni/YSZ showed a maximum power density of 369 mW/cmat 750°C, which was higher than Ni-YSZ/YSZ/LSM. Specifically, no carbon was formed in the anode after 1000 min operation. Fuel cell performance and carbon resistance were enhanced with the addition of the Ru layer.

  5. Improved Gate Dielectric Deposition and Enhanced Electrical Stability for Single-Layer MoS2 MOSFET with an AlN Interfacial Layer.

    Science.gov (United States)

    Qian, Qingkai; Li, Baikui; Hua, Mengyuan; Zhang, Zhaofu; Lan, Feifei; Xu, Yongkuan; Yan, Ruyue; Chen, Kevin J

    2016-01-01

    Transistors based on MoS2 and other TMDs have been widely studied. The dangling-bond free surface of MoS2 has made the deposition of high-quality high-k dielectrics on MoS2 a challenge. The resulted transistors often suffer from the threshold voltage instability induced by the high density traps near MoS2/dielectric interface or inside the gate dielectric, which is detrimental for the practical applications of MoS2 metal-oxide-semiconductor field-effect transistor (MOSFET). In this work, by using AlN deposited by plasma enhanced atomic layer deposition (PEALD) as an interfacial layer, top-gate dielectrics as thin as 6 nm for single-layer MoS2 transistors are demonstrated. The AlN interfacial layer not only promotes the conformal deposition of high-quality Al2O3 on the dangling-bond free MoS2, but also greatly enhances the electrical stability of the MoS2 transistors. Very small hysteresis (ΔVth) is observed even at large gate biases and high temperatures. The transistor also exhibits a low level of flicker noise, which clearly originates from the Hooge mobility fluctuation instead of the carrier number fluctuation. The observed superior electrical stability of MoS2 transistor is attributed to the low border trap density of the AlN interfacial layer, as well as the small gate leakage and high dielectric strength of AlN/Al2O3 dielectric stack. PMID:27279454

  6. Improved Gate Dielectric Deposition and Enhanced Electrical Stability for Single-Layer MoS2 MOSFET with an AlN Interfacial Layer

    Science.gov (United States)

    Qian, Qingkai; Li, Baikui; Hua, Mengyuan; Zhang, Zhaofu; Lan, Feifei; Xu, Yongkuan; Yan, Ruyue; Chen, Kevin J.

    2016-06-01

    Transistors based on MoS2 and other TMDs have been widely studied. The dangling-bond free surface of MoS2 has made the deposition of high-quality high-k dielectrics on MoS2 a challenge. The resulted transistors often suffer from the threshold voltage instability induced by the high density traps near MoS2/dielectric interface or inside the gate dielectric, which is detrimental for the practical applications of MoS2 metal-oxide-semiconductor field-effect transistor (MOSFET). In this work, by using AlN deposited by plasma enhanced atomic layer deposition (PEALD) as an interfacial layer, top-gate dielectrics as thin as 6 nm for single-layer MoS2 transistors are demonstrated. The AlN interfacial layer not only promotes the conformal deposition of high-quality Al2O3 on the dangling-bond free MoS2, but also greatly enhances the electrical stability of the MoS2 transistors. Very small hysteresis (ΔVth) is observed even at large gate biases and high temperatures. The transistor also exhibits a low level of flicker noise, which clearly originates from the Hooge mobility fluctuation instead of the carrier number fluctuation. The observed superior electrical stability of MoS2 transistor is attributed to the low border trap density of the AlN interfacial layer, as well as the small gate leakage and high dielectric strength of AlN/Al2O3 dielectric stack.

  7. Anodic Layer of Pb-Ca-Sn-Ce Alloy for Maintenance-Free Lead/Acid Batteries

    Institute of Scientific and Technical Information of China (English)

    Li Dangguo; Zhou Genshu; Lin Guanfa; Zheng Maosheng

    2005-01-01

    The anodic films of novel Pb-Ca-Sn-Ce alloy, traditional Pb-Ca-Sn and Pb-Sb alloys formed in sulfuric solution at anodic +0.9 V potential corrosion for 6 h were investigated by means of XPS, XRD methods and AC impedance measurement. The results show that the growth of Pb(Ⅱ) oxide on the new Pb-Ca-Sn-Ce alloy surface is inhibited. The AC impedance measurement shows that resistance of the corrosion layer of novel Pb-Ca-Sn-Ce alloy decreases. It is found that the novel Pb-Ca-Sn-Ce alloy can encourage the development of PbO2 in the scale, and enhance the conductivity of the anodic scale. Hence the deep recycling properties of the battery can be expected better.

  8. Effects of the interfacial layer on electrical characteristics of Al 2O 3/TiO 2/Al 2O 3 thin films for gate dielectrics

    Science.gov (United States)

    Kim, Chang Eun; Yun, Ilgu

    2012-01-01

    Effects of thermal annealing on the electrical properties of Al2O3/TiO2/Al2O3 (ATA) dielectric thin films prepared by atomic layer deposition are investigated. The structural properties and chemical states in the interfacial layer are analyzed with varying the annealing temperature. The dielectric constant and leakage current are affected by the formation of Al2O3-TiO2 composite and interfacial layer including SiOx in the interface by the annealing. The transformation of interfacial layer at the interface of the ATA/Si substrate due to the annealing is a critical point to apply ATA thin films as gate dielectric layers.

  9. Interfacial instability of turbulent two-phase stratified flow: Pressure-driven flow and thin liquid layers

    CERN Document Server

    Náraigh, Lennon Ó; Matar, Omar; Zaki, Tamer

    2009-01-01

    We consider the motion of a deformable interface that separates a fully-developed turbulent gas flow from a thin layer of laminar liquid. We outline a linear model to describe the interaction between the turbulent gas flow and the interfacial waves. This approach includes two steps. First, we derive a flat-interface base state. This comprises a velocity profile that takes account of the viscous sublayer present in the near-interfacial region of the gas, and a method for determining the wall and interfacial shear stresses as a function of the mean pressure gradient. The second step involves an Orr-Sommerfeld analysis of the Reynolds-averaged Navier-Stokes equations. We examine two distinct closure schemes for perturbation turbulent stresses, and conclude that these stresses have little effect on the stability properties. Our base-state model facilitates a definition of `slow' and `fast' waves. We use our linear stability analysis to determine the factors that affect the wave speed. For the thin films considere...

  10. Nonlinear switching in Al/Li:NiO/ITO forming-free resistive memories caused by interfacial layer

    Science.gov (United States)

    Yuan, Xin-Cai; Wei, Xian-Hua; Dai, Bo; Zeng, Hui-Zhong

    2016-01-01

    Nonlinear bipolar resistive switching (BRS) of Al/NiO/ITO without forming is demonstrated in this paper. Compared with the linear BRS needing forming, the forming-free nonlinear BRS can be operated using a smaller current about two orders at a smaller switching voltage in the same device. Different from the Joule heating mechanism of the linear BRS behavior after forming, the conduction of the nonlinear BRS is dominated by oxygen vacancy drift induced by electric field across the interface between metal Al, NiO film, and conducting ITO, in which Al/NiO interfacial layer and ITO act as a dual-oxygen reservoir. Furthermore, the doping of Li into NiO layer improves switching properties such as the ON/OFF ratio and reproducibility due to the increase of oxygen vacancy. The results imply that forming-free nonlinear BRS of binary oxides caused by interface layer is feasible in similar dual-oxygen reservoir structure.

  11. Graded composite diamond coatings with top-layer nanocrystallinity and interfacial integrity: Cross-sectional Raman mapping

    Science.gov (United States)

    Dumpala, Ravikumar; Ramamoorthy, B.; Rao, M. S. Ramachandra

    2014-01-01

    Cross-sectional structural characteristics of the CVD diamond coatings deposited on the tungsten carbide (WC-Co) substrates were analysed using Raman imaging technique. The grain size of the nanocrystalline diamond (NCD) coatings was observed to deviate from the nanocrystallinity with increasing thickness and exhibited the surface characteristics of microcrystalline diamond (MCD). However, thick diamond coatings with surface nanocrystallinity is the key requirement for load-bearing tribological applications. Tribological tests have clearly indicated the significance and need for the top-layer nanocrystallinity. Graded composite diamond coatings with an architecture of NCD/transition-layer/MCD/WC-Co are potentail candiadates to realize thick diamond coatings with top-layer nanocrystallinity. Residual stresses along the cross-section of the graded composite diamond coatings were analysed using Raman imaging technique, which confirmed the improved interfacial integrity of the graded composite diamond coatings

  12. Graded composite diamond coatings with top-layer nanocrystallinity and interfacial integrity: Cross-sectional Raman mapping

    International Nuclear Information System (INIS)

    Cross-sectional structural characteristics of the CVD diamond coatings deposited on the tungsten carbide (WC-Co) substrates were analysed using Raman imaging technique. The grain size of the nanocrystalline diamond (NCD) coatings was observed to deviate from the nanocrystallinity with increasing thickness and exhibited the surface characteristics of microcrystalline diamond (MCD). However, thick diamond coatings with surface nanocrystallinity is the key requirement for load-bearing tribological applications. Tribological tests have clearly indicated the significance and need for the top-layer nanocrystallinity. Graded composite diamond coatings with an architecture of NCD/transition-layer/MCD/WC-Co are potentail candiadates to realize thick diamond coatings with top-layer nanocrystallinity. Residual stresses along the cross-section of the graded composite diamond coatings were analysed using Raman imaging technique, which confirmed the improved interfacial integrity of the graded composite diamond coatings.

  13. Second-order solutions for random interfacial waves in N-layer density stratified fluid with steady uniform currents

    Institute of Scientific and Technical Information of China (English)

    Chen Xiao-Gang; Guo Zhi-Ping; Song Jin-Bao

    2008-01-01

    In the present paper,the random interfacial waves in N-layer density-stratified fluids moving at different steady uniform speeds are researched by using an expansion technique,and the second-order asymptotic solutions of the random displacements of the density interfaces and the associated velocity potentials in N-layer fluid are presented based on the small amplitude wave theory.The obtained results indicate that the wave-wave second-order nonlinear interactions of the wave components and the second-order nonlinear interactions between the waves and currents are described.As expected,the solutions include those derived by Chen(2006)as a special case where the steady uniform currents of the N-layer fluids are taken as zero,and the solutions also reduce to those obtained by Song(2005)for second-order solutions for random interracial waves with steady uniform currents if N=2.

  14. Modulating the optical and electrical properties of all metal oxide solar cells through nanostructuring and ultrathin interfacial layers

    International Nuclear Information System (INIS)

    The benefits and drawbacks of nanostructuring in all oxide ZnO/Cu2O solar cells were studied. The solar cells were fabricated on fluorine doped tin oxide substrates, with solution processed deposition methods. Both planar ZnO layer and Cu2O were deposited by electrodeposition while ZnO nanorods were grown by chemical bath deposition technique. It is shown that short circuit current (Jsc) of the devices increases with nanostructuring of ZnO due to electrical and optical gains. Despite improving the photocurrent, nanostructuring decreases the Voc of the device due to carrier recombination. The introduction of a thin TiO2 interfacial layer through atomic layer deposition was able to reduce the recombination.

  15. Revisiting Surface Modification of Graphite: Dual-Layer Coating for High-Performance Lithium Battery Anode Materials.

    Science.gov (United States)

    Song, Gyujin; Ryu, Jaegeon; Ko, Seunghee; Bang, Byoung Man; Choi, Sinho; Shin, Myoungsoo; Lee, Sang-Young; Park, Soojin

    2016-06-01

    Surface modification of electrode active materials has garnered considerable attention as a facile way to meet stringent requirements of advanced lithium-ion batteries. Here, we demonstrated a new coating strategy based on dual layers comprising antimony-doped tin oxide (ATO) nanoparticles and carbon. The ATO nanoparticles are synthesized via a hydrothermal method and act as electronically conductive/electrochemically active materials. The as-synthesized ATO nanoparticles are introduced on natural graphite along with citric acid used as a carbon precursor. After carbonization, the carbon/ATO-decorated natural graphite (c/ATO-NG) is produced. In the (carbon/ATO) dual-layer coating, the ATO nanoparticles coupled with the carbon layer exhibit unprecedented synergistic effects. The resultant c/ATO-NG anode materials display significant improvements in capacity (530 mA h g(-1) ), cycling retention (capacity retention of 98.1 % after 50 cycles at a rate of C/5), and low electrode swelling (volume expansion of 38 % after 100 cycles) which outperform that of typical graphite materials. Furthermore, a full-cell consisting of a c/ATO-NG anode and an LiNi0.5 Mn1.5 O4 cathode presents excellent cycle retention (capacity retention of >80 % after 100 cycles). We envision that the dual-layer coating concept proposed herein opens a new route toward high-performance anode materials for lithium-ion batteries. PMID:27027583

  16. Macroporous p-GaP Photocathodes Prepared by Anodic Etching and Atomic Layer Deposition Doping.

    Science.gov (United States)

    Lee, Sudarat; Bielinski, Ashley R; Fahrenkrug, Eli; Dasgupta, Neil P; Maldonado, Stephen

    2016-06-29

    P-type macroporous gallium phosphide (GaP) photoelectrodes have been prepared by anodic etching of an undoped, intrinsically n-type GaP(100) wafer and followed by drive-in doping with Zn from conformal ZnO films prepared by atomic layer deposition (ALD). Specifically, 30 nm ALD ZnO films were coated on GaP macroporous films and then annealed at T = 650 °C for various times to diffuse Zn in GaP. Under 100 mW cm(-2) white light illumination, the resulting Zn-doped macroporous GaP consistently exhibit strong cathodic photocurrent when measured in aqueous electrolyte containing methyl viologen. Wavelength-dependent photoresponse measurements of the Zn-doped macroporous GaP revealed enhanced collection efficiency at wavelengths longer than 460 nm, indicating that the ALD doping step rendered the entire material p-type and imparted the ability to sustain a strong internal electric field that preferentially drove photogenerated electrons to the GaP/electrolyte interface. Collectively, this work presents a doping strategy with a potentially high degree of controllability for high-aspect ratio III-V materials, where the ZnO ALD film is a practical dopant source for Zn. PMID:27254534

  17. Solution-processed cathode interfacial layer materials for high-efficiency polymer solar cells

    OpenAIRE

    Biao Xiao; Hongbin Wu; Yong Cao

    2015-01-01

    Polymer solar cells (PSCs) are a new type of renewable energy source currently being extensively investigated due to perceived advantages; such as being lightweight, low-cost and because of the unlimited materials resource. The power conversion efficiency of state-of-the-art PSCs has increased dramatically in the past few years, obtained mainly through the development of new electron donor polymers, acceptors, and novel device structures through the use of various electrode interfacial materi...

  18. Linearity optimization of atomic layer deposited ZrO2 metal-insulator-metal capacitors by inserting interfacial Zr-doped chromia layers

    Science.gov (United States)

    Lutzer, B.; Simsek, S.; Zimmermann, C.; Stoeger-Pollach, M.; Bethge, O.; Bertagnolli, E.

    2016-03-01

    In order to improve the electrical behaviour of metal-insulator-metal capacitors with ZrO2 insulator grown by Atomic Layer Deposition, the influence of the insertion of interfacial Cr layers between Pt electrodes and the zirconia is investigated. An improvement of the α-voltage coefficient of capacitance as low as 567 ppm/V2 is achieved for a single layer of Cr while maintaining a high capacitance density of 10.7 fF/μm2 and a leakage current of less than 1.2 × 10-8 A/cm2 at +1 V. The role of the interface is discussed by means of X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy showing the formation of Zr stabilized chromia oxide phase with a dielectric constant of 16.

  19. Effects of ultrathin AlAs interfacial layer on the structure and optical properties of GaInP epilayer grown on germanium

    Energy Technology Data Exchange (ETDEWEB)

    Jia, S.P. [Key Lab. for New Type of Functional Materials in Hebei Province, School of Material and Engineering, Hebei University of Technology, Tianjin 300130 (China); Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Chen, G.F. [Key Lab. for New Type of Functional Materials in Hebei Province, School of Material and Engineering, Hebei University of Technology, Tianjin 300130 (China); He, W. [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Department of Teaching Basic Courses, The Chinese People' s Armed Police Force Academy, Langfang, Hebei Province 065000 (China); Dai, P.; Chen, J.X. [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Lu, S.L., E-mail: sllu2008@sinano.ac.cn [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Yang, H. [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China)

    2014-10-30

    Highlights: • GaInP with an ultrathin AlAs interfacial layers was grown on Ge by MOVPE. • The 5 Å AlAs results in a decrease of PL intensity from the Ge-based complexes. • The increase of AlAs thickness from 5 Å to 5 nm did not improve inhibiting effect. • The incorporation of AlAs results in an increased ordered degree of GaInP. - Abstract: Structure and optical properties of GaInP epilayer with the ultrathin interfacial layers grown on germanium by metal–organic vapor-phase epitaxy (MOVPE) were characterized by high resolution transmission electron microscopy (HRTEM), photoluminescence (PL), Raman as well as surface morphology measurement. A five angstroms (5 Å) AlAs interfacial layer results in the decrease of PL intensity arising from the emission of [Ge{sub (Ga,In)} − V{sub (Ga,In)}] complex. With the incorporation of AlAs interfacial layer, an increased ordered degree of GaInP epilayer is observed. On the basis of the combination of step–terrace-reconstruction (STR) mode with the dimer-induced-stress model, a CuPt-B type ordering of GaInP which is related to AlAs reconstruction with 2× periodicity process is proposed to explain this effect. Long range order occurs as a consequence of the minimization of the strain energy with increased interfacial layer thickness from 5 Å to 5 nm.

  20. Effects of ultrathin AlAs interfacial layer on the structure and optical properties of GaInP epilayer grown on germanium

    International Nuclear Information System (INIS)

    Highlights: • GaInP with an ultrathin AlAs interfacial layers was grown on Ge by MOVPE. • The 5 Å AlAs results in a decrease of PL intensity from the Ge-based complexes. • The increase of AlAs thickness from 5 Å to 5 nm did not improve inhibiting effect. • The incorporation of AlAs results in an increased ordered degree of GaInP. - Abstract: Structure and optical properties of GaInP epilayer with the ultrathin interfacial layers grown on germanium by metal–organic vapor-phase epitaxy (MOVPE) were characterized by high resolution transmission electron microscopy (HRTEM), photoluminescence (PL), Raman as well as surface morphology measurement. A five angstroms (5 Å) AlAs interfacial layer results in the decrease of PL intensity arising from the emission of [Ge(Ga,In) − V(Ga,In)] complex. With the incorporation of AlAs interfacial layer, an increased ordered degree of GaInP epilayer is observed. On the basis of the combination of step–terrace-reconstruction (STR) mode with the dimer-induced-stress model, a CuPt-B type ordering of GaInP which is related to AlAs reconstruction with 2× periodicity process is proposed to explain this effect. Long range order occurs as a consequence of the minimization of the strain energy with increased interfacial layer thickness from 5 Å to 5 nm

  1. Controlled surface oxidation of multi-layered graphene anode to increase hole injection efficiency in organic electronic devices

    Science.gov (United States)

    Han, Tae-Hee; Kwon, Sung-Joo; Seo, Hong-Kyu; Lee, Tae-Woo

    2016-03-01

    Ultraviolet ozone (UVO) surface treatment of graphene changes its sp2-hybridized carbons to sp3-bonded carbons, and introduces oxygen-containing components. Oxidized graphene has a finite energy band gap, so UVO modification of the surface of a four-layered graphene anode increases its surface ionization potential up to ∼5.2 eV and improves the hole injection efficiency (η) in organic electronic devices by reducing the energy barrier between the graphene anode and overlying organic layers. By controlling the conditions of the UVO treatment, the electrical properties of the graphene can be tuned to improve η. This controlled surface modification of the graphene will provide a way to achieve efficient and stable flexible displays and solid-state lighting.

  2. Ultrathin ZnS and ZnO Interfacial Passivation Layers for Atomic-Layer-Deposited HfO2 Films on InP Substrates.

    Science.gov (United States)

    Kim, Seung Hyun; Joo, So Yeong; Jin, Hyun Soo; Kim, Woo-Byoung; Park, Tae Joo

    2016-08-17

    Ultrathin ZnS and ZnO films grown by atomic layer deposition (ALD) were employed as interfacial passivation layers (IPLs) for HfO2 films on InP substrates. The interfacial layer growth during the ALD of the HfO2 film was effectively suppressed by the IPLs, resulting in the decrease of electrical thickness, hysteresis, and interface state density. Compared with the ZnO IPL, the ZnS IPL was more effective in reducing the interface state density near the valence band edge. The leakage current density through the film was considerably lowered by the IPLs because the film crystallization was suppressed. Especially for the film with the ZnS IPL, the leakage current density in the low-voltage region was significantly lower than that observed for the film with the ZnO IPL, because the direct tunneling current was suppressed by the higher conduction band offset of ZnS with the InP substrate. PMID:27467383

  3. Effects of interfacial transition layers on the electrical properties of individual Fe 30 Co 61 Cu 9 /Cu multilayer nanowires

    KAUST Repository

    Ma, Hongbin

    2016-01-01

    In this work, we accurately measure the electrical properties of individual Fe30Co61Cu9/Cu multilayered nanowires using nanomanipulators in in situ scanning electron microscopy to reveal that interfacial transition layers are influential in determining their transport behaviors. We investigate the morphology, crystal structure and chemistry of the Fe30Co61Cu9/Cu multilayered nanowires to characterize them at the nanoscale. We also compare the transport properties of these multilayered nanowires to those of individual pure Cu nanowires and to those of alloy Fe30Co61Cu9 nanowires. The multilayered nanowires with a 50 nm diameter had a remarkable resistivity of approximately 5.41 × 10-7 Ω m and a failure current density of 1.54 × 1011 A m-2. Detailed analysis of the electrical data reveals that interfacial transition layers influence the electrical properties of multilayered nanowires and are likely to have a strong impact on the life of nanodevices. This work contributes to a basic understanding of the electrical parameters of individual magnetic multilayered nanowires for their application as functional building blocks and interconnecting leads in nanodevices and nanoelectronics, and also provides a clear physical picture of a single multilayered nanowire which explains its electrical resistance and its source of giant magnetoresistance. © The Royal Society of Chemistry 2016.

  4. Modified surface morphology of a novel Ti-24Nb-4Zr-7.9Sn titanium alloy via anodic oxidation for enhanced interfacial biocompatibility and osseointegration.

    Science.gov (United States)

    Li, Xiang; Chen, Tao; Hu, Jing; Li, Shujun; Zou, Qin; Li, Yunfeng; Jiang, Nan; Li, Hui; Li, Jihua

    2016-08-01

    The Ti-24Nb-4Zr-7.9Sn titanium alloy (Ti2448) has shown potential for use in biomedical implants, because this alloy possesses several important mechanical properties, such as a high fracture strength, low elastic modulus, and good corrosion resistance. In this study, we aimed to produce a hierarchical nanostructure on the surface of Ti2448 to endow this alloy with favorable biological properties. The chemical composition of Ti2448 (64.0wt% Ti, 23.9wt% Nb, 3.9wt% Zr, and 8.1wt% Sn) gives this material electrochemical properties that lead to the generation of topographical features under standard anodic oxidation. We characterized the surface properties of pure Ti (Ti), nanotube-Ti (NT), Ti2448, and nanotube-Ti2448 (NTi2448) based on surface morphology (scanning electron microscopy and atomic force microscopy), chemical and phase compositions (X-ray diffraction and X-ray photoelectron spectroscopy), and wettability (water contact angle). We evaluated the biocompatibility and osteointegration of implant surfaces by observing the behavior of bone marrow stromal cells (BMSCs) cultured on the surfaces in vitro and conducting histological analysis after in vivo implantation of the modified materials. Our results showed that a hierarchical structure with a nanoscale bone-like layer was achieved along with nanotube formation on the Ti2448 surface. The surface characterization data suggested the superior biocompatibility of the NTi2448 surface in comparison with the Ti, NT, and Ti2448 surfaces. Moreover, the NTi2448 surface showed better biocompatibility for BMSCs in vitro and better osteointegration in vivo. Based on these results, we conclude that anodic oxidation facilitated the formation of a nanoscale bone-like structure and nanotubes on Ti2448. Unlike the modified titanium surfaces developed to date, the NTi2448 surface, which presents both mechanical compatibility and bioactivity, offers excellent biocompatibility and osteointegration, suggesting its potential for

  5. 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.

  6. Modification of SnO2 Anodes by Atomic Layer Deposition for High Performance Lithium Ion Batteries

    KAUST Repository

    Yesibolati, Nulati

    2013-05-01

    Tin dioxide (SnO2) is considered one of the most promising anode materials for Lithium ion batteries (LIBs), due to its large theoretical capacity and natural abundance. However, its low electronic/ionic conductivities, large volume change during lithiation/delithiation and agglomeration prevent it from further commercial applications. In this thesis, we investigate modified SnO2 as a high energy density anode material for LIBs. Specifically two approaches are presented to improve battery performances. Firstly, SnO2 electrochemical performances were improved by surface modification using Atomic Layer Deposition (ALD). Ultrathin Al2O3 or HfO2 were coated on SnO2 electrodes. It was found that electrochemical performances had been enhanced after ALD deposition. In a second approach, we implemented a layer-by-layer (LBL) assembled graphene/carbon-coated hollow SnO2 spheres as anode material for LIBs. Our results indicated that the LBL assembled electrodes had high reversible lithium storage capacities even at high current densities. These superior electrochemical performances are attributed to the enhanced electronic conductivity and effective lithium diffusion, because of the interconnected graphene/carbon networks among nanoparticles of the hollow SnO2 spheres.

  7. Energy level alignment of electrically doped hole transport layers with transparent and conductive indium tin oxide and polymer anodes

    Science.gov (United States)

    Fehse, Karsten; Olthof, Selina; Walzer, Karsten; Leo, Karl; Johnson, Robert L.; Glowatzki, Hendrik; Bröker, Benjamin; Koch, Norbert

    2007-10-01

    Using ultraviolet photoemission spectroscopy, we investigated the energy level alignment at the interfaces of typical anodes used in organic electronics, indium tin oxide (ITO) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), with the oligomeric hole transport material N ,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD), and studied the influence of electrical interface doping by the strong electron acceptor tetrafluoro tetracyanoquinodimethane (F4-TCNQ). The fundamentally different anode materials with work functions of 4.40eV (ITO) and 4.85eV (PEDOT:PSS) show different hole injection barriers, which also depend on the thickness of the F4-TCNQ interface dopant layer. PEDOT:PSS anodes exhibit a consistently lower hole injection barrier to MeO-TPD compared to ITO by 0.1eV. We attribute this low hole injection barrier to additional charge transfer reactions at the PEDOT:PSS/MeO-TPD interface. In contrast, the deposition of the electron acceptor at the interface helps significantly to lower the hole injection barrier for ITO anodes.

  8. Tuning indium tin oxide work function with solution-processed alkali carbonate interfacial layers for high-efficiency inverted organic photovoltaic cells

    International Nuclear Information System (INIS)

    Selective electron collection by an interfacial layer modified indium tin oxide cathode is critically important for achieving high-efficiency inverted structure organic photovoltaic (OPV) cells. Here, we demonstrate that solution-processed alkali carbonates, such as Li2CO3, Na2CO3, K2CO3, Rb2CO3, Cs2CO3, are good interfacial layer materials. Both carbonate concentration and annealing conditions can affect cathode work function and surface roughness. By proper optimization, different alkali carbonates can be almost equally effective as the cathode interfacial layer. Furthermore, good device performance can be achieved at a low annealing temperature (<50 ° C), which allows for potential applications in solution-processed inverted OPV cells on plastic substrates. This work indicates that alkali carbonates, not just cesium carbonate, are valid choices as the cathode interlayer in inverted OPV devices. (paper)

  9. Development of Plasma-Sprayed Molybdenum Carbide-Based Anode Layers with Various Metal Oxides for SOFC

    Science.gov (United States)

    Faisal, N. H.; Ahmed, R.; Katikaneni, S. P.; Souentie, S.; Goosen, M. F. A.

    2015-12-01

    Air plasma-sprayed (APS) coatings provide an ability to deposit a range of novel fuel cell materials at competitive costs. This work develops three separate types of composite anodes (Mo-Mo2C/Al2O3, Mo-Mo2C/ZrO2, Mo-Mo2C/TiO2) using a combination of APS process parameters on Hastelloy®X for application in intermediate temperature proton-conducting solid oxide fuel cells. Commercially available carbide of molybdenum powder catalyst (Mo-Mo2C) and three metal oxides (Al2O3, ZrO2, TiO2) was used to prepare three separate composite feedstock powders to fabricate three different anodes. Each of the modified composition anode feedstock powders included a stoichiometric weight ratio of 0.8:0.2. The coatings were characterized by scanning electron microscopy, energy dispersive spectroscopy, x-ray diffraction, nanoindentation, and conductivity. We report herein that three optimized anode layers of thicknesses between 200 and 300 µm and porosity as high as 20% for Mo-Mo2C/Al2O3 (250-µm thick) and Mo-Mo2C/TiO2 (300 µm thick) and 17% for Mo-Mo2C/ZrO2 (220-µm thick), controllable by a selection of the APS process parameters with no addition of sacrificial pore-forming material. The nanohardness results indicate the upper layers of the coatings have higher values than the subsurface layers in coatings with some effect of the deposition on the substrate. Mo-Mo2C/ZrO2 shows high electrical conductivity.

  10. Electrostatic layer-by-layer a of platinum-loaded multiwall carbon nanotube multilayer: A tunable catalyst film for anodic methanol oxidation

    International Nuclear Information System (INIS)

    A simple layer-by-layer (LBL) electrostatic adsorption technique was developed for deposition of films composed of alternating layers of positively charged poly(diallyldimethylammonium chloride) (PDDA) and negatively charged multiwall carbon nanotubes bearing platinum nanoparticles (Pt-CNTs). PDDA/Pt-CNT film structure and morphology up to six layers were characterized by scanning electron microscopy and ultraviolet-visible spectroscopy, showing the Pt-CNT layers to be porous and uniformly deposited within the multilayer films. Electrochemical properties of the PDDA/Pt-CNT films, as well as electrocatalytic activity toward methanol oxidation, were investigated with cyclic voltammetry. Significant activity toward anodic methanol oxidation was observed and is readily tunable through changing film thickness and/or platinum-nanoparticle loading. Overall, the observed properties of these PDDA/Pt-CNT multilayer films indicated unique potential for application in direct methanol fuel cell

  11. Layered oxygen-deficient double perovskite as an efficient and stable anode for direct hydrocarbon solid oxide fuel cells.

    Science.gov (United States)

    Sengodan, Sivaprakash; Choi, Sihyuk; Jun, Areum; Shin, Tae Ho; Ju, Young-Wan; Jeong, Hu Young; Shin, Jeeyoung; Irvine, John T S; Kim, Guntae

    2015-02-01

    Different layered perovskite-related oxides are known to exhibit important electronic, magnetic and electrochemical properties. Owing to their excellent mixed-ionic and electronic conductivity and fast oxygen kinetics, cation layered double perovskite oxides such as PrBaCo2O5 in particular have exhibited excellent properties as solid oxide fuel cell oxygen electrodes. Here, we show for the first time that related layered materials can be used as high-performance fuel electrodes. Good redox stability with tolerance to coking and sulphur contamination from hydrocarbon fuels is demonstrated for the layered perovskite anode PrBaMn2O5+δ (PBMO). The PBMO anode is fabricated by in situ annealing of Pr0.5Ba0.5MnO3-δ in fuel conditions and actual fuel cell operation is demonstrated. At 800 °C, layered PBMO shows high electrical conductivity of 8.16 S cm(-1) in 5% H2 and demonstrates peak power densities of 1.7 and 1.3 W cm(-2) at 850 °C using humidified hydrogen and propane fuels, respectively. PMID:25532072

  12. Role of interfacial oxygen on the quality and strain stability of pseudomorphic silicon-germanium layers grown on Si substrates

    Science.gov (United States)

    Bedell, S. W.; Adam, T. N.; Turansky, A.; Sadana, D. K.

    2011-02-01

    A commercially available 300 mm single-wafer UHV-CVD reactor was used to grow strained pseudomorphic Si 0.79Ge 0.21 layers beyond the critical thickness on Si substrates. A unique in situ method of introducing controlled amounts of oxygen at the growth interface, combined with a very sensitive defect etching technique, was used to study the crystal defects present in the strained SiGe layers immediately after growth and after thermal annealing over large areas (many square centimeters). The etching results showed that the density of growth-related defects (stacking faults) originating from residual O at the epitaxy/substrate interface increases exponentially when the interfacial O concentration exceeds a level of about 10 13 O/cm 2 as measured by secondary ion mass spectroscopy. By defect etching the annealed samples we demonstrate that all the strain-relieving defects (dislocations) we observed originate from these growth defects. Therefore, we confirm previous claims that the strain metastability of low-misfit SiGe layers is controlled mainly by the initial concentration of growth defects. These findings have important implications regarding historical studies of metastability in the strained SiGe/Si system as well as contemporary efforts to grow highly metastable strained layers for IC applications.

  13. Mixture of Fluids involving Entropy Gradients and Acceleration Waves in Interfacial Layers

    CERN Document Server

    Gouin, Henri

    2008-01-01

    Through an Hamiltonian action we write down the system of equations of motions for a mixture of thermocapillary fluids under the assumption that the internal energy is a function not only of the gradient of the densities but also of the gradient of the entropies of each component. A Lagrangian associated with the kinetic energy and the internal energy allows to obtain the equations of momentum for each component and for the barycentric motion of the mixture. We obtain also the balance of energy and we prove that the equations are compatible with the second law of thermodynamics. Though the system is of parabolic type, we prove that there exist two tangential acceleration waves that characterize the interfacial motion. The dependence of the internal energy of the entropy gradients is mandatory for the existence of this kind of waves. The differential system is non-linear but the waves propagate without distortion due to the fact that they are linearly degenerate (exceptional waves).

  14. Study of synthesis parameters and active layer morphology of interfacially polymerized polyamide-polysulfone membranes

    OpenAIRE

    Hermans, Sanne; Bernstein, Roy; Volodin, Alexander; Vankelecom, Ivo

    2015-01-01

    Thin film composite (TFC) polyamide membranes were prepared on a polysulfone support membrane and the effect of various synthesis conditions on the active layer morphology, the physicochemical properties and the membrane performance was investigated. The support membrane porosity factor had a significant effect on the TFC membrane performance. A polyamide top layer was formed within 15 s of reaction. Prolonging the reaction time, although resulting in a thicker active layer, only had a minor ...

  15. Comparison of hydrolytic and non-hydrolytic atomic layer deposition chemistries: Interfacial electronic properties at alumina-silicon interfaces

    International Nuclear Information System (INIS)

    We report the differences in the passivation and electronic properties of aluminum oxide (Al2O3) deposited on silicon via traditional hydrolytic atomic layer deposition (ALD) and non-hydrolytic (NH) ALD chemistries. Traditional films were grown using trimethylaluminum (TMA) and water and NHALD films grown using TMA and isopropanol at 300 °C. Hydrolytically grown ALD films contain a smaller amount of fixed charge than NHALD films (oxide fixed charge Qf Traditional = −8.1 × 1011 cm−2 and Qf NHALD = −3.6 × 1012 cm−2), and a larger degree of chemical passivation than NHALD films (density of interface trap states, Dit Traditional = 5.4 × 1011 eV−1 cm−2 and Dit NHALD = 2.9 × 1012 eV−1 cm−2). Oxides grown with both chemistries were found to have a band gap of 7.1 eV. The conduction band offset was 3.21 eV for traditionally grown films and 3.38 eV for NHALD. The increased Dit for NHALD films may stem from carbon impurities in the oxide layer that are at and near the silicon surface, as evidenced by both the larger trap state time constant (τTraditional = 2.2 × 10−9 s and τNHALD = 1.7 × 10−7 s) and the larger carbon concentration. We have shown that the use of alcohol-based oxygen sources in NHALD chemistry can significantly affect the resulting interfacial electronic behavior presenting an additional parameter for understanding and controlling interfacial electronic properties at semiconductor-dielectric interfaces

  16. Comparison of hydrolytic and non-hydrolytic atomic layer deposition chemistries: Interfacial electronic properties at alumina-silicon interfaces

    Science.gov (United States)

    Marstell, Roderick J.; Strandwitz, Nicholas C.

    2015-11-01

    We report the differences in the passivation and electronic properties of aluminum oxide (Al2O3) deposited on silicon via traditional hydrolytic atomic layer deposition (ALD) and non-hydrolytic (NH) ALD chemistries. Traditional films were grown using trimethylaluminum (TMA) and water and NHALD films grown using TMA and isopropanol at 300 °C. Hydrolytically grown ALD films contain a smaller amount of fixed charge than NHALD films (oxide fixed charge Qf Traditional = -8.1 × 1011 cm-2 and Qf NHALD = -3.6 × 1012 cm-2), and a larger degree of chemical passivation than NHALD films (density of interface trap states, Dit Traditional = 5.4 × 1011 eV-1 cm-2 and Dit NHALD = 2.9 × 1012 eV-1 cm-2). Oxides grown with both chemistries were found to have a band gap of 7.1 eV. The conduction band offset was 3.21 eV for traditionally grown films and 3.38 eV for NHALD. The increased Dit for NHALD films may stem from carbon impurities in the oxide layer that are at and near the silicon surface, as evidenced by both the larger trap state time constant (τTraditional = 2.2 × 10-9 s and τNHALD = 1.7 × 10-7 s) and the larger carbon concentration. We have shown that the use of alcohol-based oxygen sources in NHALD chemistry can significantly affect the resulting interfacial electronic behavior presenting an additional parameter for understanding and controlling interfacial electronic properties at semiconductor-dielectric interfaces.

  17. Electrochemical Characteristics of Diamond-Like Carbon/Cr Double-Layer Coating on Silicon Monoxide-Graphite Composite Anode for Li-Ion Batteries

    International Nuclear Information System (INIS)

    The electrochemical behavior of a SiOx–graphite composite anode with a diamond-like carbon (DLC)–Cr double-layer coating and employed in a Li-ion secondary cell was studied to determine whether the coating improved the electrochemical characteristics of SiOx. The DLC layer was coated through plasma-enhanced chemical vapor deposition, and the Cr layer was formed by physical vapor deposition. The formation of the coating layer was confirmed by transmission electron microscopy, Raman spectroscopy, and electron microprobe analysis. The charge capacity of a coated-anode cell (591 mA·h·g−1) was found to be higher than that of a bare-anode cell (517 mA·h·g−1) after the 1st cycle. Further, the 50th-cycle capacity retention of the coated-anode cell (83%) was higher than that of the bare-anode cell (59%) at a 0.5 C-rate. The electrochemical characteristics of the coated-anode cell were investigated by impedance analysis, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. Because of good mechanical properties of the DLC-Cr coatings and high electrical conductivity of Cr, double layer coating enhances the electrochemical behavior of SiOx as a supplementary coating material

  18. Formation of niobium oxide film with duplex layers by galvanostatic anodization

    International Nuclear Information System (INIS)

    Studies on niobium anodization in the mixture of 1 M H3PO4 and 1 wt % HF at galvanostatic anodization are described here in detail. Interestingly, duplex niobium oxide consisting of thick barrier oxide and correspondingly thick porous oxide was prepared at a constant current density of higher than 0.3 mAcm-2, whereas simple porous type oxide was formed at a current density of lower than 0.3 mAcm-2. In addition, simple barrier or porous type oxide was obtained by galvanostatic anodization at a single electrolyte of either 1 M H3PO4 or 1 wt % HF, respectively. The formation mechanism of duplex type structures was ascribed to different forming voltages required for moving anions

  19. INFLUENCE OF TEMPERATURE ON BEHAVIOR OF THE INTERFACIAL CRACK BETWEEN THE TWO LAYERS

    Directory of Open Access Journals (Sweden)

    Jelena M Djoković

    2010-01-01

    Full Text Available In this paper is considered a problem of the semi-infinite crack at the interface between the two elastic isotropic layers in conditions of the environmental temperature change. The energy release rate needed for the crack growth along the interface was determined, for the case when the two-layered sample is cooled from the temperature of the layers joining down to the room temperature. It was noticed that the energy release rate increases with the temperature difference increase. In the paper is also presented the distribution of stresses in layers as a function of the temperature and the layers' thickness variations. Analysis is limited to the case when the bimaterial sample is exposed to uniform temperature.

  20. Versatile electron-collecting interfacial layer by in situ growth of silver nanoparticles in nonconjugated polyelectrolyte aqueous solution for polymer solar cells.

    Science.gov (United States)

    Yuan, Kai; Chen, Lie; Chen, Yiwang

    2014-10-01

    Novel PEIE-Ag composites by in situ growth of silver nanoparticles in poly(ethylenimine)-ethoxylated (PEIE) aqueous solution are explored as an efficient interfacial layer for improving inverted polymer solar cells (PSCs) performance. The hybrid PEIE-Ag interfacial material is simple to fabricate only via ultraviolet irradiation with good water-solubility and unique film formation. The generated Ag nanoparticles can anchor in the PEIE polymer chains to form a conductive continuous interpenetrating network structure. Combining of the advantages of PEIE and Ag nanoparticles, the PEIE-Ag shows enhanced charge transport, electron selective and collection, and improved light-harvesting, mainly due to the surface plasmon resonance effect, better energy alignment induced by the formation of ideal dipole layer, as well as the improved conductivity. These distinguished interfacial properties result in the power conversion efficiency of inverted PSCs based on poly[4,8-bis(2-ethyl-hexyl-thiophene-5-yl)-benzo[1,2-b:4,5-b]dithiophene-2,6-diyl]-alt-[2-(2-ethyl-hexanoyl)-thieno[3,4-b]thiophen-4,6-diyl] (PBDTTT-C-T) and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) photoactive layer substantially improved up to 7.66% from 6.11%. Moreover, the device performance is insensitively dependent on the thickness of the PEIE-Ag interfacial layer, broadening the thicknesses selection window for interfacial materials. These results demonstrate that PEIE-Ag is a potential interfacial material compatible with roll-to-roll techniques and suitable for printed electronic devices. PMID:25207753

  1. Optimization of Residual Stresses in MMC's Using Compensating/Compliant Interfacial Layers. Part 2: OPTCOMP User's Guide

    Science.gov (United States)

    Pindera, Marek-Jerzy; Salzar, Robert S.; Williams, Todd O.

    1994-01-01

    A user's guide for the computer program OPTCOMP is presented in this report. This program provides a capability to optimize the fabrication or service-induced residual stresses in uni-directional metal matrix composites subjected to combined thermo-mechanical axisymmetric loading using compensating or compliant layers at the fiber/matrix interface. The user specifies the architecture and the initial material parameters of the interfacial region, which can be either elastic or elastoplastic, and defines the design variables, together with the objective function, the associated constraints and the loading history through a user-friendly data input interface. The optimization procedure is based on an efficient solution methodology for the elastoplastic response of an arbitrarily layered multiple concentric cylinder model that is coupled to the commercial optimization package DOT. The solution methodology for the arbitrarily layered cylinder is based on the local-global stiffness matrix formulation and Mendelson's iterative technique of successive elastic solutions developed for elastoplastic boundary-value problems. The optimization algorithm employed in DOT is based on the method of feasible directions.

  2. Characterization of thin hydroxyapatite layers formed on anodic titanium oxide films containing Ca and P by hydrothermal treatment.

    Science.gov (United States)

    Ishizawa, H; Ogino, M

    1995-09-01

    An anodic titanium oxide film containing Ca and P (AOFCP) was formed on commercially pure titanium which was anodized in an electrolytic solution of dissolved beta-glycerophosphate (beta-GP) and calcium acetate (CA). Hydroxyapatite (HA) crystals were precipitated by hydrothermally heating the AOFCP at 300 degrees C. After hydrothermal treatment, the film was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray microanalysis (EDX), and tensile tests. The morphology, composition, and amount of HA crystals precipitated were significantly affected by the composition of the electrolytes. Near-stoichiometric HA crystals with high crystallinity were precipitated completely covering the AOFCP surface at specific electrolyte concentrations. The HA layers were thin at 1-2 microns in thickness. The adhesive strength of the film increased with decreasing electrolyte concentration and the maximum value was about 40 MPa. In vitro tests for 300 days suggested that the stability of the film was high. The high adhesive strength may result from the AOFCP existing as an intermediate layer between the HA layer and a titanium substrate. The intervention of the AOFCP may have prevented abrupt changes in Ca and P content at an HA coating-titanium interface as seen in a plasma-sprayed one. The porous TiO2 matrix of the AOFCP may be suitable for nucleation sites of HA crystals, as well as SiO2 matrix of silicate bioactive glasses or glass ceramics. PMID:8567705

  3. Highly Efficient Simplified Organic Light-Emitting Diodes Utilizing F4-TCNQ as an Anode Buffer Layer

    Institute of Scientific and Technical Information of China (English)

    DONG Mu-Sen; WU Xiao-Ming; HUA Yu-Lin; QI Qing-Jin; YIN Shou-Gen

    2010-01-01

    @@ We demonstrate that the electroluminescent performances of organic light-emitting diodes(OLEDs)are significantly improved by evaporating a thin F4-TCNQ film as an anode buffer layer on the ITO anode.The optimum Alq3-based OLEDs with F4-TCNQ buffer layer exhibit a lower turn-on voltage of 2.6 V,a higher brightness of39820cd/m2 at 13 V,and a higher current efficiency of 5.96cd/A at 6 V,which are obviously superior to those of the conventional device(turn-on voltage of 4.1 V,brightness of 18230cd/m2 at 13 V,and maximum current efficiency of 2.74 cd/A at 10 V).Furthermore,the buffered devices with F4-TCNQ as the buffer layer could not only increase the efficiency but also simplify the fabrication process compared with the p-doped devices in which F4-TCNQ is doped into/3-NPB as p-HTL(3.11 cd/A at 7 V).The reason why the current efficiency of the p-doped devices is lower than that of the buffered devices is analyzed based on the concept of doping,the measurement of absorption and photoluminescence spectra of the organic materials,and the current density-voltage characteristics of the corresponding hole-only devices.

  4. Fabrication of a Ni nano-imprint stamp for an anti-reflective layer using an anodic aluminum oxide template.

    Science.gov (United States)

    Park, Eun-Mi; Lim, Seung-Kyu; Ra, Senug-Hyun; Suh, Su-Jung

    2013-11-01

    Aluminum anodizing can alter pore diameter, density distribution, periodicity and layer thickness in a controlled way. Because of this property, porous type anodic aluminum oxide (AAO) was used as a template for nano-structure fabrication. The alumina layer generated at a constant voltage increased the pore size from 120 nm to 205 nm according to an increasing process time from 60 min to 150 min. The resulting fabricated AAO templates had pore diameters at or less than 200 nm. Ni was sputtered as a conductive layer onto this AAO template and electroplated using DC and pulse power. Comparing these Ni stamps, those generated from electroplating using on/reverse/off pulsing had an ordered pillar array and maintained the AAO template morphology. This stamp was used for nano-imprinting on UV curable resin coated glass wafer. Surface observations via electron microscopy showed that the nano-imprinted patterned had the same shape as the AAO template. A soft mold was subsequently fabricated and nano-imprinted to form a moth-eye structure on the glass wafer. An analysis of the substrate transmittance using UV-VIS/NIR spectroscopy showed that the transmittance of the substrate with the moth-eye structure was 5% greater that the non-patterned substrate. PMID:24245297

  5. Interfacial Water Structure in Langmuir Monolayer and Gibbs Layer Probed by Sum Frequency Generation Vibrational Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    张贞; 郭源

    2012-01-01

    Langmuir monolayer and Gibbs layer exhibit surface-active properties and it can be used as simple model systems to investigate the physicochemical properties of biological membranes. In this report, we presented the OH stretching vibration of H2O in the 4"-n-pentyl-4-cyano-p-terphenyl (5CT), nonadecanenitrile (C18CN) Langmuir monolayer and compared them with CH3CN Gibbs layer at the air/water interface with polarization SFG-VS. This study demonstrated that the hydrogen bond network is different in the Langmuir monolayer of 5CT, C18CN from CH3CN Gibbs layer at the air/water interface which showed two different water structures on the different surface layer. The results provided a deeper insight into understanding the hydrogen bond on the interfaces.

  6. Effects of interfacial layer wettability and thickness on the coating morphology and sirolimus release for drug-eluting stent.

    Science.gov (United States)

    Bedair, Tarek M; Yu, Seung Jung; Im, Sung Gap; Park, Bang Ju; Joung, Yoon Ki; Han, Dong Keun

    2015-12-15

    Drug-eluting stents (DESs) have been used to treat coronary artery diseases by placing in the arteries. However, current DESs still suffer from polymer coating defects such as delamination and peeling-off that follows stent deployment. Such coating defects could increase the roughness of DES and might act as a source of late or very late thrombosis and might increase the incident of restenosis. In this regard, we modified the cobalt-chromium (Co-Cr) alloy surface with hydrophilic poly(2-hydroxyethyl methacrylate) (PHEMA) or hydrophobic poly(2-hydroxyethyl methacrylate)-grafted-poly(caprolactone) (PHEMA-g-PCL) brushes. The resulting surfaces were biocompatible and biodegradable, which could act as anchoring layer for the drug-in-polymer matrix coating. The two modifications were characterized by ATR-FTIR, XPS, water contact angle measurements, SEM and AFM. On the control and modified Co-Cr samples, a sirolimus (SRL)-containing poly(D,L-lactide) (PDLLA) were ultrasonically spray-coated, and the drug release was examined for 8weeks under physiological conditions. The results demonstrated that PHEMA as a primer coating improved the coating stability and degradation morphology, and drug release profile for short-term as compared to control Co-Cr, but fails after 7weeks in physiological buffer. On the other hand, the hydrophobic PHEMA-g-PCL brushes not only enhanced the stability and degradation morphology of the PDLLA coating layer, but also sustained SRL release for long-term. At 8-week of release test, the surface morphologies and release profiles of coated PDLLA layers verified the beneficial effect of hydrophobic PCL brushes as well as their thickness on coating stability. Our study concludes that 200nm thickness of PHEMA-g-PCL as interfacial layer affects the stability and degradation morphology of the biodegradable coating intensively to be applied for various biodegradable-based DESs. PMID:26319336

  7. Instability of Two-Layer Rayleigh-Bénard Convection with Interfacial Thermocapillary Effect

    Institute of Scientific and Technical Information of China (English)

    LIU Qiu-Sheng(刘秋生); ZHOU Bing-Hong(周炳红); NGUYEN THI Henri; HU Wen-Rui(胡文瑞)

    2004-01-01

    The linear instability analysis of the Rayleigh-Marangoni-Bénard convection in a two-layer system of silicon oil 10cS and fluorinert FC70 liquids are performed in a larger range of two-layer depth ratios Hr from 0.2 to 5.0 for different total depth H(≤)12 mm. Our results are different from the previous study on the Rayleigh-Bénard instability and show strong effects of thermocapillary force at the interface on the time-dependent oscillations arising from the onset of instability convection.

  8. Two dimensional layered Co0.85Se nanosheets as a high-capacity anode for lithium-ion batteries.

    Science.gov (United States)

    Zhou, Jisheng; Wang, Ye; Zhang, Jun; Chen, Tupei; Song, Huaihe; Yang, Hui Ying

    2016-08-11

    In recent years, two-dimensional (2D) layered transitional metal chalcogenides (TMCs) have received much attention as promising electrode materials in energy storage. Although recent reports on 2D TMC nanostructures have demonstrated promising electrochemical performances, the major scientific challenge is to develop a viable synthesis process to produce layered structures of chalcogenides (Co, Ni or Fe based TMCs) as anode materials. In this work, we propose the synthesis of layered Co0.85Se nanosheets in a solution based method by using a 2D oriented attachment strategy. The as-prepared Co0.85Se nanosheets exhibit specific capacities as high as 675 mA h g(-1) at 100 mA g(-1). When the current densities were further increased to 200, 500 and 1000 mA g(-1), the reversible capacities can still reach up to 645, 574 and 493 mA h g(-1) with excellent cycling life of 95, 85 and 73%, respectively. Li-ion storage performance of layered Co0.85Se nanosheets is higher than that of Co0.85Se microspheres as well as cobalt sulfide. The superior electrochemical performance of Co0.85Se nanosheets is attributed to their 2D layered structure which enhances electrical conductivity and improves diffusion pathways of the Li-ion within the host material. The synthesis method described in this work serves as a general route for the design and preparation of other 2D layered TMCs. PMID:27471135

  9. HA coating on titanium with nanotubular anodized TiO2 intermediate layer via electrochemical deposition

    Institute of Scientific and Technical Information of China (English)

    WANG Yue-qin; TAO Jie; WANG Ling; HE Ping-ting; WANG Tao

    2008-01-01

    Hydroxyapatite (HA) coating has been prepared on titanium substrate through an electrochemical deposition approach.In order to improve the bonding strength between HA coating and Ti substrate,a well oriented and uniform titanium oxide nanotube array on the surface of titanium substrate was applied by means of anodic oxidation pre-treatment.Then the calcium hydrogen phosphate (CaHPO4-2H2O,DCPD) coating,as the precursor of hydroxyapatite coating,was electrodeposited on the anodized Ti.At the initial stage of electro-deposition,the DCPD crystals,in nanometer precipitates,are anchored in and between the tubes.With increasing the deposition time,the nanometer DCPD crystals are connected together to form a continuous coating on titanium oxide nanotube array.Finally,the DCPD coating is converted into hydroxyapatite one simply by being immersed in alkaline solution.

  10. SnO2 anode surface passivation by atomic layer deposited HfO2 improves li-ion battery performance

    KAUST Repository

    Yesibolati, Nulati

    2014-03-14

    For the first time, it is demonstrated that nanoscale HfO2 surface passivation layers formed by atomic layer deposition (ALD) significantly improve the performance of Li ion batteries with SnO2-based anodes. Specifically, the measured battery capacity at a current density of 150 mAg -1 after 100 cycles is 548 and 853 mAhg-1 for the uncoated and HfO2-coated anodes, respectively. Material analysis reveals that the HfO2 layers are amorphous in nature and conformably coat the SnO2-based anodes. In addition, the analysis reveals that ALD HfO2 not only protects the SnO2-based anodes from irreversible reactions with the electrolyte and buffers its volume change, but also chemically interacts with the SnO2 anodes to increase battery capacity, despite the fact that HfO2 is itself electrochemically inactive. The amorphous nature of HfO2 is an important factor in explaining its behavior, as it still allows sufficient Li diffusion for an efficient anode lithiation/delithiation process to occur, leading to higher battery capacity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Novel Combination of Efficient Perovskite Solar Cells with Low Temperature Processed Compact TiO2 Layer via Anodic Oxidation.

    Science.gov (United States)

    Du, Yangyang; Cai, Hongkun; Wen, Hongbin; Wu, Yuxiang; Huang, Like; Ni, Jian; Li, Juan; Zhang, Jianjun

    2016-05-25

    In this work, a facile and low temperature processed anodic oxidation approach is proposed for fabricating compact and homogeneous titanium dioxide film (AO-TiO2). In order to realize morphology and thickness control of AO-TiO2, the theory concerning anodic oxidation (AO) is unveiled and the influence of relevant parameters during the process of AO such as electrolyte ingredient and oxidation voltage on AO-TiO2 formation is observed as well. Meanwhile, we demonstrate that the planar perovskite solar cells (p-PSCs) fabricated in ambient air and utilizing optimized AO-TiO2 as electron transport layer (ETL) can deliver repeatable power conversion efficiency (PCE) over 13%, which possess superior open-circuit voltage (Voc) and higher fill factor (FF) compared to its counterpart utilizing conventional high temperature processed compact TiO2 (c-TiO2) as ETL. Through a further comparative study, it is indicated that the improvement of device performance should be attributed to more effective electron collection from perovskite layer to AO-TiO2 and the decrease of device series resistance. Furthermore, hysteresis effect about current density-voltage (J-V) curves in TiO2-based p-PSCs is also unveiled. PMID:27150310

  12. Core-shell Si@TiO2 nanosphere anode by atomic layer deposition for Li-ion batteries

    Science.gov (United States)

    Bai, Ying; Yan, Dong; Yu, Caiyan; Cao, Lina; Wang, Chunlei; Zhang, Jinshui; Zhu, Huiyuan; Hu, Yong-Sheng; Dai, Sheng; Lu, Junling; Zhang, Weifeng

    2016-03-01

    Silicon (Si) has been regarded as next-generation anode for high-energy lithium-ion batteries (LIBs) due to its high Li storage capacity (4200 mA h g-1). However, the mechanical degradation and resultant capacity fade critically hinder its practical application. In this regard, we demonstrate that nanocoating of Si spheres with a 3 nm titanium dioxide (TiO2) layer via atomic layer deposition (ALD) can utmostly balance the high conductivity and the good structural stability to improve the cycling stability of Si core material. The resultant sample, Si@TiO2-3 nm core-shell nanospheres, exhibits the best electrochemical performance of all with a highest initial Coulombic efficiency and specific charge capacity retention after 50 cycles at 0.1C (82.39% and 1580.3 mA h g-1). In addition to making full advantage of the ALD technique, we believe that our strategy and comprehension in coating the electrode and the active material could provide a useful pathway towards enhancing Si anode material itself and community of LIBs.

  13. Improved light extraction of LYSO scintillator by the photonic structure from a layer of anodized aluminum oxide

    International Nuclear Information System (INIS)

    As a promising scintillator in the field of medical imaging systems, LYSO with its high refractive index suffers from a low light extraction efficiency due to the total internal reflection. Here, we demonstrate that a photonic structure formed by an anodized aluminum oxide layer can enhance the light extraction efficiency by the outcoupling the light trapped in the crystal. An enhancement of light output by 25% can be achieved by an AAO layer covered on the surface of LYSO. The imperfect periodicity of AAO can lead to a consistent enhancement for the entire range of emission wavelength and directionality. Such enhanced light output is practical and attractive for use in the scintillation detection systems. It is important to note that the fabrication method of AAO is simple and low-cost for the large area applications, which is obviously advantageous over the expensive traditional methods such as electron beam lithography

  14. Improved light extraction of LYSO scintillator by the photonic structure from a layer of anodized aluminum oxide

    Science.gov (United States)

    Zhu, Zhichao; Liu, Bo; Cheng, Chuanwei; Zhang, Haifeng; Wu, Shuang; Gu, Mu; Chen, Hong; Chen, Liang; Liu, Jinliang; Ouyang, Xiaoping

    2015-06-01

    As a promising scintillator in the field of medical imaging systems, LYSO with its high refractive index suffers from a low light extraction efficiency due to the total internal reflection. Here, we demonstrate that a photonic structure formed by an anodized aluminum oxide layer can enhance the light extraction efficiency by the outcoupling the light trapped in the crystal. An enhancement of light output by 25% can be achieved by an AAO layer covered on the surface of LYSO. The imperfect periodicity of AAO can lead to a consistent enhancement for the entire range of emission wavelength and directionality. Such enhanced light output is practical and attractive for use in the scintillation detection systems. It is important to note that the fabrication method of AAO is simple and low-cost for the large area applications, which is obviously advantageous over the expensive traditional methods such as electron beam lithography.

  15. Inverted polymer solar cells with enhanced fill factor by inserting the potassium stearate interfacial modification layer

    Science.gov (United States)

    Li, Jiangsheng; Jiu, Tonggang; Li, Bairu; Kuang, Chaoyang; Chen, Qiushan; Ma, Sushuang; Shu, Jie; Fang, Junfeng

    2016-05-01

    A thin potassium stearate (KSt) film combined with an optimized ZnO film was introduced to improve the fill factor (FF) of highly efficient inverted polymer solar cells (PSCs). Atomic force microscopy and contact angle measurements were used to show that the introduction of KSt did not change the morphology of interlayer. On the contrary, it is beneficial for the spread of the active layer on the interlayer. The origin of enhanced FF was systematically studied by the ideal current-voltage model for a single heterojunction solar cell and electrochemical impedance spectroscopy. On the basis of the data analysis, the reduced charge recombination loss was responsible for this improved FF. At last, when KSt was replaced by sodium stearate (NaSt), the similar experiment phenomenon was observed. This indicates that inserting a metallic stearate modified layer is a promising strategy to enhance inverted PSCs performance.

  16. Running interfacial waves in two-layer fluid system subject to longitudinal vibrations

    OpenAIRE

    Goldobin, Denis S.; Pimenova, Anastasiya V.; Kovalevskaya, Kseniya V.; Lyubimov, Dmitry V.; Lyubimova, Tatyana P.

    2014-01-01

    We study the waves at the interface between two thin horizontal layers of immiscible fluids subject to high-frequency horizontal vibrations. Previously, the variational principle for energy functional, which can be adopted for treatment of quasi-stationary states of free interface in fluid dynamical systems subject to vibrations, revealed existence of standing periodic waves and solitons in this system. However, this approach does not provide regular means for dealing with evolutionary proble...

  17. Running interfacial waves in a two-layer fluid system subject to longitudinal vibrations.

    Science.gov (United States)

    Goldobin, D S; Pimenova, A V; Kovalevskaya, K V; Lyubimov, D V; Lyubimova, T P

    2015-05-01

    We study the waves at the interface between two thin horizontal layers of immiscible fluids subject to high-frequency horizontal vibrations. Previously, the variational principle for energy functional, which can be adopted for treatment of quasistationary states of free interface in fluid dynamical systems subject to vibrations, revealed the existence of standing periodic waves and solitons in this system. However, this approach does not provide regular means for dealing with evolutionary problems: neither stability problems nor ones associated with propagating waves. In this work, we rigorously derive the evolution equations for long waves in the system, which turn out to be identical to the plus (or good) Boussinesq equation. With these equations one can find all the time-independent-profile solitary waves (standing solitons are a specific case of these propagating waves), which exist below the linear instability threshold; the standing and slow solitons are always unstable while fast solitons are stable. Depending on initial perturbations, unstable solitons either grow in an explosive manner, which means layer rupture in a finite time, or falls apart into stable solitons. The results are derived within the long-wave approximation as the linear stability analysis for the flat-interface state [D.V. Lyubimov and A.A. Cherepanov, Fluid Dynamics 21, 849 (1986)] reveals the instabilities of thin layers to be long wavelength. PMID:26066252

  18. Comparison of hydrolytic and non-hydrolytic atomic layer deposition chemistries: Interfacial electronic properties at alumina-silicon interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Marstell, Roderick J.; Strandwitz, Nicholas C., E-mail: strand@lehigh.edu [Department of Materials Science and Engineering and Center for Advanced Materials and Nanotechnology, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)

    2015-11-14

    We report the differences in the passivation and electronic properties of aluminum oxide (Al{sub 2}O{sub 3}) deposited on silicon via traditional hydrolytic atomic layer deposition (ALD) and non-hydrolytic (NH) ALD chemistries. Traditional films were grown using trimethylaluminum (TMA) and water and NHALD films grown using TMA and isopropanol at 300 °C. Hydrolytically grown ALD films contain a smaller amount of fixed charge than NHALD films (oxide fixed charge Q{sub f} {sub Traditional} = −8.1 × 10{sup 11 }cm{sup −2} and Q{sub f} {sub NHALD} = −3.6 × 10{sup 12 }cm{sup −2}), and a larger degree of chemical passivation than NHALD films (density of interface trap states, D{sub it} {sub Traditional} = 5.4 × 10{sup 11 }eV{sup −1 }cm{sup −2} and D{sub it} {sub NHALD} = 2.9 × 10{sup 12 }eV{sup −1 }cm{sup −2}). Oxides grown with both chemistries were found to have a band gap of 7.1 eV. The conduction band offset was 3.21 eV for traditionally grown films and 3.38 eV for NHALD. The increased D{sub it} for NHALD films may stem from carbon impurities in the oxide layer that are at and near the silicon surface, as evidenced by both the larger trap state time constant (τ{sub Traditional} = 2.2 × 10{sup −9} s and τ{sub NHALD} = 1.7 × 10{sup −7} s) and the larger carbon concentration. We have shown that the use of alcohol-based oxygen sources in NHALD chemistry can significantly affect the resulting interfacial electronic behavior presenting an additional parameter for understanding and controlling interfacial electronic properties at semiconductor-dielectric interfaces.

  19. Carbon-tolerant solid oxide fuel cells using NiTiO3 as an anode internal reforming layer

    Science.gov (United States)

    Wang, Zhiquan; Wang, Zhenbin; Yang, Wenqiang; Peng, Ranran; Lu, Yalin

    2014-06-01

    In this work, adding a NiTiO3 (NTO) reforming layer is firstly adopted as a low cost method to improve the carbon tolerance in solid oxide fuel cells. XRD patterns suggest that NTO has a good chemical compatibility with the YSZ electrolyte, and NTO can be totally reduced to Ni and TiO2 when exposing to the H2 atmosphere. Maximum power densities for the cells with the NTO layers at 700 °C are 270 mWcm-2 with wet H2 fuel, and 236 mWcm-2 with wet methane fuel, respectively. Improved discharging stability for the cells with NTO layers has also been observed. The current density remains unchanged for the cells with NTO layers during a 26 h test, while it drops to zero within 1 h for the cells without NTO. Above electro-performance and long term stability tests suggest that fabricating a NTO reforming layer on the anode surface is an efficient and inexpensive method to realize highly carbon tolerant SOFCs.

  20. Assembly and organization of poly(3-hexylthiophene) brushes and their potential use as novel anode buffer layers for organic photovoltaics.

    Science.gov (United States)

    Alonzo, José; Kochemba, W Michael; Pickel, Deanna L; Ramanathan, Muruganathan; Sun, Zhenzhong; Li, Dawen; Chen, Jihua; Sumpter, Bobby G; Heller, William T; Kilbey, S Michael

    2013-10-01

    Buffer layers that control electrochemical reactions and physical interactions at electrode/film interfaces are key components of an organic photovoltaic cell. Here the structure and properties of layers of semi-rigid poly(3-hexylthiophene) (P3HT) chains tethered at a surface are investigated, and these functional systems are applied in an organic photovoltaic device. Areal density of P3HT chains is readily tuned through the choice of polymer molecular weight and annealing conditions, and insights from optical absorption spectroscopy and semiempirical quantum calculation methods suggest that tethering causes intrachain defects that affect co-facial π-stacking of brush chains. Because of their ability to modify oxide surfaces, P3HT brushes are utilized as an anode buffer layer in a P3HT-PCBM (phenyl-C₆₁-butyric acid methyl ester) bulk heterojunction device. Current-voltage characterization shows a significant enhancement in short circuit current, suggesting the potential of these novel nanostructured buffer layers to replace the PEDOT:PSS buffer layer typically applied in traditional P3HT-PCBM solar cells. PMID:23955069

  1. Propagation regimes of interfacial solitary waves in a three-layer fluid

    Directory of Open Access Journals (Sweden)

    O. E. Kurkina

    2015-01-01

    Full Text Available Long weakly nonlinear finite-amplitude internal waves in a fluid consisting of three inviscid immiscible layers of arbitrary thickness and constant densities (stable configuration, Boussinesq approximation bounded by a horizontal rigid bottom from below and by a rigid lid at the surface are described up to the second order of perturbation theory in small parameters of nonlinearity and dispersion. First, a pair of alternatives of appropriate KdV-type equations with the coefficients depending on the parameters of the fluid (layer positions and thickness, density jumps are derived for the displacements of both modes of internal waves and for each interface between the layers. These equations are integrable for a very limited set of coefficients and do not allow for proper description of several near-critical cases when certain coefficients vanish. A more specific equation allowing for a variety of solitonic solutions and capable of resolving most of near-critical situations is derived by means of the introduction of another small parameter that describes the properties of the medium and rescaling of the ratio of small parameters. This procedure leads to a pair of implicitly interrelated alternatives of Gardner equation (KdV-type equations with combined nonlinearity for the two interfaces. We present a detailed analysis of the relationships for the solutions for the disturbances at both interfaces and various regimes of the appearance and propagation properties of soliton solutions to these equations depending on the combinations of the parameters of the fluid. It is shown both the quadratic and the cubic nonlinear terms vanish for several realistic configurations of such a fluid.

  2. Interfacial characteristics of polyethylene terephthalate-based piezoelectric multi-layer films

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Z.H. [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, National Science Council Core Facilities Laboratory for Nano-Science and Nano-Technology in Kaohsiung-Pingtung area, Taiwan (China); Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, Hsinchu 310, Taiwan (China); Pan, C.T., E-mail: panct@mail.nsysu.edu.tw [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, National Science Council Core Facilities Laboratory for Nano-Science and Nano-Technology in Kaohsiung-Pingtung area, Taiwan (China); Chen, Y.C. [Department of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Liang, P.H. [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China)

    2013-03-01

    The study examines the deformation between interfaces and the adhesion mechanism of multi-layer flexible electronic composites. Indium tin oxide (ITO), aluminum (Al), and zinc oxide (ZnO) were deposited on a polyethylene terephthalate (PET) substrate using radio frequency magnetron sputtering at room temperature to form flexible structures (e.g., ITO/PET, Al/PET, ZnO/ITO/PET, and ZnO/Al/PET) for piezoelectric transducers. ITO and Al films are used as the conductive layers. A ZnO thin film shows a high (002) c-axis preferred orientation at 2θ = 34.45° and excellent piezoelectric properties. Nanoscratching and nano-indention testing were conducted to analyze the adhesion following periodic mechanical stress. Additionally, two Berkovich and conical probes with a curvature radius of 40 nm and 10 μm are examined for the scratching test. A 4-point probe is used to measure the conductive properties. The plastic deformation between the ductile Al film and PET substrate is observed using scanning electron microscopy to examine the chip formation on the ITO/PET. Delamination between the ZnO and Al/PET substrate was not observed. The result suggests that ZnO film has excellent adhesion with Al/PET compared to ITO/PET. - Highlights: ► Interfaces and adhesion mechanism of multi-layer flexible electronic composites ► Polyethylene terephthalate (PET) based flexible structures ► Nano-scratching and nano-indention tests were used to analyze adhesion. ► Using two various probes of Berkovich and conical ► Piezoelectric zinc oxide film has excellent adhesion with aluminum/PET.

  3. Interfacial characteristics of polyethylene terephthalate-based piezoelectric multi-layer films

    International Nuclear Information System (INIS)

    The study examines the deformation between interfaces and the adhesion mechanism of multi-layer flexible electronic composites. Indium tin oxide (ITO), aluminum (Al), and zinc oxide (ZnO) were deposited on a polyethylene terephthalate (PET) substrate using radio frequency magnetron sputtering at room temperature to form flexible structures (e.g., ITO/PET, Al/PET, ZnO/ITO/PET, and ZnO/Al/PET) for piezoelectric transducers. ITO and Al films are used as the conductive layers. A ZnO thin film shows a high (002) c-axis preferred orientation at 2θ = 34.45° and excellent piezoelectric properties. Nanoscratching and nano-indention testing were conducted to analyze the adhesion following periodic mechanical stress. Additionally, two Berkovich and conical probes with a curvature radius of 40 nm and 10 μm are examined for the scratching test. A 4-point probe is used to measure the conductive properties. The plastic deformation between the ductile Al film and PET substrate is observed using scanning electron microscopy to examine the chip formation on the ITO/PET. Delamination between the ZnO and Al/PET substrate was not observed. The result suggests that ZnO film has excellent adhesion with Al/PET compared to ITO/PET. - Highlights: ► Interfaces and adhesion mechanism of multi-layer flexible electronic composites ► Polyethylene terephthalate (PET) based flexible structures ► Nano-scratching and nano-indention tests were used to analyze adhesion. ► Using two various probes of Berkovich and conical ► Piezoelectric zinc oxide film has excellent adhesion with aluminum/PET

  4. Layer-by-layer assembled graphene-coated mesoporous SnO2 spheres as anodes for advanced Li-ion batteries

    KAUST Repository

    Shahid, Muhammad

    2014-10-01

    We report layer-by-layer (LBL) assembly of graphene/carbon-coated mesoporous SnO2 spheres (Gr/C-SnO2 spheres), without binder and conducting additives, as anode materials with excellent Li-ion insertion-extraction properties. Our results indicate that these novel LBL assembled electrodes have high reversible Li storage capacity, improved cycling, and especially good rate performance, even at high specific currents. The superior electrochemical performance offered by these LBL assembled Gr/C-SnO2 spheres is attributed to the enhanced electronic conductivity and effective diffusion of Li ions in the interconnected network of nanoparticles forming the mesoporous SnO2 spheres. © 2014 Elsevier B.V. All rights reserved.

  5. Multiple moving interfacial cracks between two dissimilar piezoelectric layers under electromechanical loading

    Science.gov (United States)

    Nourazar, Mahsa; Ayatollahi, Mojtaba

    2016-07-01

    The dynamic problem of several moving cracks at the interface between two dissimilar piezoelectric materials is analyzed. The combined out-of-plane mechanical and in-plane electrical loads are applied to the layers. Fourier transforms are used to reduce the problem to a system of singular integral equations with simple Cauchy kernel. The integral equations are solved numerically by converting to a system of linear algebraic equations and by using a collocation technique. The results presented consist of the stress intensity factors and the electric displacement intensity factors. It is found that generally the field intensity factors increase with increasing crack propagation speed.

  6. Lithium hydroxide doped tris(8-hydroxyquinoline) aluminum as an effective interfacial layer in inverted bottom-emission organic light-emitting diodes

    International Nuclear Information System (INIS)

    Lithium hydroxide doped tris(8-hydroxyquinoline) aluminum (Alq3:LiOH) is used as an effective interfacial layer for the fabrication of efficient inverted bottom-emission organic light-emitting diodes (IBOLEDs). When 15% LiOH was doped into an Alq3 electron-transporting layer, the device properties such as the turn-on voltage, maximum luminance, and device efficiency improved, becoming better than those obtained with LiF doping and comparable to those of β-naphthylphenylbiphenyl diamine (NPB)/Alq3-based OLEDs with conventional geometry. Electrical analysis reveals that LiOH-doped Alq3 layers have an enhanced electron injection and transport ability. X-ray and ultraviolet photoelectron spectroscopy results clearly show that the dipole layer formed at the indium tin oxide (ITO)/organic interface contributed to the reduction of the ITO work function, resulting in a decrease of the electron injection barrier. The enhanced electron injection and transport efficiency improves the charge carrier balance in IBOLEDs and leads to better device efficiency. Furthermore, improved morphology of the organic layer can be obtained by doping LiOH into Alq3, which improves device operational stability under thermal stress. - Highlights: • Inverted bottom-emission organic light-emitting diodes with Alq3:LiOH interfacial layer were investigated. • Alq3:LiOH layers possess an enhanced electron injection and transporting ability. • The dipole layer is formed at the Alq3:LiOH/indium tin oxide interface. • Alq3:LiOH interfacial layer stabilizes the surface morphology of the Alq3 film

  7. Lithium hydroxide doped tris(8-hydroxyquinoline) aluminum as an effective interfacial layer in inverted bottom-emission organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kao, Po-Ching, E-mail: pckao@mail.ncyu.edu.tw; Lu, Chia-Wen; Lin, Jie-Han; Lin, Yeh-Kai

    2014-11-03

    Lithium hydroxide doped tris(8-hydroxyquinoline) aluminum (Alq{sub 3}:LiOH) is used as an effective interfacial layer for the fabrication of efficient inverted bottom-emission organic light-emitting diodes (IBOLEDs). When 15% LiOH was doped into an Alq{sub 3} electron-transporting layer, the device properties such as the turn-on voltage, maximum luminance, and device efficiency improved, becoming better than those obtained with LiF doping and comparable to those of β-naphthylphenylbiphenyl diamine (NPB)/Alq{sub 3}-based OLEDs with conventional geometry. Electrical analysis reveals that LiOH-doped Alq{sub 3} layers have an enhanced electron injection and transport ability. X-ray and ultraviolet photoelectron spectroscopy results clearly show that the dipole layer formed at the indium tin oxide (ITO)/organic interface contributed to the reduction of the ITO work function, resulting in a decrease of the electron injection barrier. The enhanced electron injection and transport efficiency improves the charge carrier balance in IBOLEDs and leads to better device efficiency. Furthermore, improved morphology of the organic layer can be obtained by doping LiOH into Alq{sub 3}, which improves device operational stability under thermal stress. - Highlights: • Inverted bottom-emission organic light-emitting diodes with Alq{sub 3}:LiOH interfacial layer were investigated. • Alq{sub 3}:LiOH layers possess an enhanced electron injection and transporting ability. • The dipole layer is formed at the Alq{sub 3}:LiOH/indium tin oxide interface. • Alq{sub 3}:LiOH interfacial layer stabilizes the surface morphology of the Alq{sub 3} film.

  8. Enhanced photoelectrochemical performance of WO3/Ti photoanode due to in situ formation of a thin interfacial composite layer

    Science.gov (United States)

    Lee, Won Jae; Shinde, Pravin S.; Go, Geun Ho; Doh, Chil Hoon

    2013-04-01

    Nanostructured WO3 thin films were prepared on titanium sheet substrates using a doctor blade technique. X-ray diffraction, Raman and field emission scanning electron microscopy studies revealed that the synthesized WO3 films are having monoclinic crystal structure, porous, polycrystalline with average grain size of ∼50 nm. The photoelectrochemical responses of WO3 films prepared on treated Ti sheets were recorded in 0.5 M H2SO4 electrolyte under simulated 100 mW/cm2 illumination. WO3 film prepared on polished Ti sheet showed considerable enhancement in photocurrent as compared to WO3 films made on unpolished and pre-oxidized Ti sheets. These results suggest that in situ formation of a thin WOx-TiOy interfacial composite layer and improved adhesion of WO3 nanoparticles owing to increased reactive sites on polished Ti substrate play a significant role in enhancing the photoresponse. Such photoanodes are potential candidates in photoelectrochemical water splitting system for hydrogen generation.

  9. Possibilities of Increase of Adhesion of the Cubic Boron Nitride Coatings by Applying an Interfacial Layers

    Institute of Scientific and Technical Information of China (English)

    MaciejKupczyk

    2004-01-01

    In the work the chosen investigations of the adhesion force of thin, superhard coatings to the cutting edges made of cemented carbides are presented. For identification of the adhesion force of coatings to substrate an automatic scratch tester constructed at Poznan University of Technology was applied. The estimation of the adhesion force (value of critical load measured during scratch test) was carried out on the base of the vibration signal. Results of investigations are pointed at the influence of a surface preparation (degreasing, etching, low and high-temperature sputtering) on a critical load values. It was round that the most effective method for surface preparation is low temperature sputtering. The influence of the TiC+Al2O3+TiN interracial layer on increase of the adhesion force of BN coating to cemented carbides substrate was observed.

  10. Iron oxide nanotube layer fabricated with electrostatic anodization for heterogeneous Fenton like reaction

    International Nuclear Information System (INIS)

    Highlights: • Iron oxide nanotube was newly fabricated with potentiostatic anodization of Fe0 foil. • Cyanide was oxidized more effectively with the iron oxide nanotube and H2O2, resulting in fast oxidation of cyanide and cyanate. • This nanotube of Fe2O3 on Fe0 metal can replace conventional particulate iron catalysts in Fenton-like processes. - Abstract: Iron oxide nanotubes (INT) were fabricated with potentiostatic anodization of zero valent iron foil in 1 M Na2SO4 containing 0.5 wt% NH4F electrolyte, holding the potential at 20, 40, and 60 V for 20 min, respectively. Field emission scanning electron microscopy and X-ray diffractometry were used to evaluate the morphology and crystalline structure of the INT film. The potential of 40 V for 20 min was observed to be optimal to produce an optimal catalytic film. Cyanide dissolved in water was degraded through the Fenton-like reaction using the INT film with hydrogen peroxide (H2O2). In case of INT-40 V in the presence of H2O2 3%, the first-order rate constant was found to be 1.7 × 10−2 min−1, and 1.2 × 10−2 min−1 with commercial hematite powder. Degradation of cyanide was much less with only H2O2. Therefore, this process proposed in this work can be an excellent alternative to traditional catalysts for Fenton-like reaction

  11. Highly transparent and conductive double-layer oxide thin films as anodes for organic light-emitting diodes

    International Nuclear Information System (INIS)

    Double-layer transparent conducting oxide thin film structures containing In-doped CdO (CIO) and Sn-doped In2O3 (ITO) layers were grown on glass by metal-organic chemical vapor deposition and ion-assisted deposition (IAD), respectively, and used as anodes for polymer light-emitting diodes (PLEDs). These films have a very low overall In content of 16 at. %. For 180-nm-thick CIO/ITO films, the sheet resistance is 5.6 Ω/□, and the average optical transmittance is 87.1% in the 400-700 nm region. The overall figure of merit (Φ=T10/Rsheet) of the double-layer CIO/ITO films is significantly greater than that of single-layer CIO, IAD-ITO, and commercial ITO films. CIO/ITO-based PLEDs exhibit comparable or superior device performance versus ITO-based control devices. CIO/ITO materials have a much lower sheet resistance than ITO, rendering them promising low In content electrode materials for large-area optoelectronic devices

  12. Development of electrostatic supercapacitors by atomic layer deposition on nanoporous anodic aluminium oxides for energy harvesting applications

    Directory of Open Access Journals (Sweden)

    Lucia eIglesias

    2015-03-01

    Full Text Available Nanomaterials can provide innovative solutions for solving the usual energy harvesting and storage drawbacks that take place in conventional energy storage devices based on batteries or electrolytic capacitors, because they are not fully capable for attending the fast energy demands and high power densities required in many of present applications. Here, we report on the development and characterization of novel electrostatic supercapacitors made by conformal Atomic Layer Deposition on the high open surface of nanoporous anodic alumina membranes employed as templates. The structure of the designed electrostatic supercapacitor prototype consists of successive layers of Aluminium doped Zinc Oxide, as the bottom and top electrodes, together Al2O3 as the intermediate dielectric layer. The conformality of the deposited conductive and dielectric layers, together with their composition and crystalline structure have been checked by XRD and electron microscopy techniques. Impedance measurements performed for the optimized electrostatic supercapacitor device give a high capacitance value of 200 µF/cm2 at the frequency of 40 Hz, which confirms the theoretical estimations for such kind of prototypes, and the leakage current reaches values around of 1.8 mA/cm2 at 1 V. The high capacitance value achieved by the supercapacitor prototype together its small size turns these devices in outstanding candidates for using in energy harvesting and storage applications.

  13. Inert Electrodes Program: Characterization of the reaction layer or film on PNL (Pacific Northwest Laboratory) inert anodes: Progress Report for April-December 1989

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, C.F. Jr.; Stice, N.D.

    1990-05-01

    This progress report addresses activities conducted at Pacific Northwest Laboratory (PNL) between April 1989 and December 1989 to characterize the reaction layer or film previously proposed by PNL to form on cermet anodes during the electrolytic production of aluminum in Hall-Heroult cells. Formation of this resistive film was thought to protect the cermet anode from corrosion reactions that would otherwise occur in the molten cryolite electrolyte. The results of potential-step studies, electrochemical impedance spectroscopy, and post-mortem microscopic analysis of polarized anodes suggest that the processes of corrosion of the metallic phase of the anode and the production of oxygen gas are separable and exhibit very different kinetic behavior. The corrosion reactions occur predominantly at low anode potentials, appear to show diffusion control, and may be related to the porosity of the anode. The oxygen production reaction is the predominant reaction above 2.2 V, exhibits activation control, occurs primarily on the surface of the anode, and is accompanied by an increase in surface roughness at higher current densities. Evidence presented in this report indicates that the production of oxygen shuts down the corrosion reactions, possibly through a pore-blocking mechanism. In addition, roughness effects may help explain some of the impedance relationships previously observed by PNL for these anodes. Although the present results do not rule out the formation of a protective layer or film, they strongly indicate mechanisms other than the formation of a macroscopic protective film for the apparent attenuation of corrosion reactions at typical operating current densities. 11 refs.

  14. Two-layer interfacial flows beyond the Boussinesq approximation: a Hamiltonian approach

    CERN Document Server

    Camassa, R; Ortenzi, G

    2015-01-01

    The theory of integrable systems of Hamiltonian PDEs and their near-integrable deformations is used to study evolution equations resulting from vertical-averages of the Euler system for two-layer stratified flows in an infinite 2D channel. The Hamiltonian structure of the averaged equations is obtained directly from that of the Euler equations through the process of Hamiltonian reduction. Long-wave asymptotics together with the Boussinesq approximation of neglecting the fluids' inertia is then applied to reduce the leading order vertically averaged equations to the shallow-water Airy system, and thence, in a non-trivial way, to the dispersionless non-linear Schr\\"odinger equation. The full non-Boussinesq system for the dispersionless limit can then be viewed as a deformation of this well known equation. In a perturbative study of this deformation, it is shown that at first order the deformed system possesses an infinite sequence of constants of the motion, thus casting this system within the framework of comp...

  15. Interfacial hydrodynamic drag on nanowires embedded in thin oil films and protein layers.

    Science.gov (United States)

    Lee, Myung Han; Lapointe, Clayton P; Reich, Daniel H; Stebe, Kathleen J; Leheny, Robert L

    2009-07-21

    We investigate the motion of ferromagnetic nanowires confined to nanometer-scale oil films at an air/aqueous interface in response to the application of external magnetic fields and field gradients. By varying the oil viscosity, film thickness, and wire length, we cover two regimes of response suggested by theory: one where the surface viscosity is expected to dominate the wire's motion and one where the subphase viscosity is expected to dominate [Levine, A. J.; Liverpool, T. B.; MacKintosh, F. C. Phys. Rev. E 2004, 69, 021503]. For wire motion parallel to the long axis of the wire, the observed drag agrees reasonably with theoretical predictions. However, the drag on wires moving perpendicular to their long axis or rotating about a short axis is unexpectedly insensitive to the film properties over the full range of measurements. This behavior is in contrast to the rotational and translational drag on nanowires in molecularly thin protein layers, which follow theoretical expectations. The observations in the oil films, which are explained in terms of the manner in which the wire immerses dynamically in the film and subphase, demonstrate how the effective drag viscosity of an aspherical particle confined to a fluid interface can depend on its direction of motion. PMID:19594180

  16. Experimental Study of the Morphology and Dynamics of Gas-Laden Layers Under the Anodes in an Air-Water Model of Aluminum Reduction Cells

    Science.gov (United States)

    Vékony, Klára; Kiss, László I.

    2012-10-01

    The bubble layer formed under an anode and the bubble-induced flow play a significant role in the aluminum electrolysis process. The bubbles covering the anode bottom reduce the efficient surface that can carry current. In our experiments, we filmed and studied the bubble layer under the anode in a real-size air-water electrolysis cell model. Three different flow regimes were found depending on the gas generation rate. The covering factor was found to be proportional to the gas generation rate and inversely proportional to the angle of inclination. A correlation between the average height of the entire bubble layer and the position under the anode was determined. From this correlation and the measured contact sizes, the volume of the accumulated gas was calculated. The sweeping effect of large bubbles was observed. Moreover, the small bubbles under the inner edge of the anode were observed to move backward as a result of the escape of huge gas pockets, which means large momentum transport occurs in the bath.

  17. Quantitative assessment of the interfacial roughness in multi-layered materials using image analysis: Application to oxidation in ceramic-based materials

    OpenAIRE

    Le Roux, Sabine; Deschaux-Beaume, Frédéric; Cutard, Thierry; Lours, Philippe

    2015-01-01

    A method is developed to characterize interfacial roughness of layered materials. A series of contiguous images is acquired with a Scanning Electron Microscope on polished cross-sections. Using image analysis algorithms based on mathematical morphology operations, interface profiles are extracted and mathematically processed to calculate standard surface roughness parameters. In addition, morphological criteria describing the interface tortuosity are determined, such as the " normalized rumpl...

  18. Atomic Layer Deposited MoS2 as a Carbon and Binder Free Anode in Li-ion Battery

    International Nuclear Information System (INIS)

    Molybdenum sulfide is deposited by atomic layer deposition (ALD) using molybdenum hexacarbonyl and hydrogen sulfide. Film growth is studied using in-situ quartz crystal microbalance, ex-situ X-ray reflectivity and ellipsometry. Deposition chemistry is further investigated with in-situ Fourier transform infrared spectroscopy. Self-limiting nature of the reaction is observed, typical of ALD. Saturated growth rate of 2.5 Å per cycle at 170 °C is obtained. As-deposited films are found amorphous in nature. As-grown films are tested as lithium-ion battery anode under half cell configuration. Electrochemical charge-discharge measurements demonstrate a stable cyclic performance with good capacity retention. Discharge capacity of 851 mAh g−1 is obtained after 50 cycles which corresponds to 77% of capacity retention of the initial capacity

  19. Iron oxide nanotube layer fabricated with electrostatic anodization for heterogeneous Fenton like reaction

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jun-Won; Park, Jae-Woo, E-mail: jaewoopark@hanyang.ac.kr

    2014-05-01

    Highlights: • Iron oxide nanotube was newly fabricated with potentiostatic anodization of Fe{sup 0} foil. • Cyanide was oxidized more effectively with the iron oxide nanotube and H{sub 2}O{sub 2}, resulting in fast oxidation of cyanide and cyanate. • This nanotube of Fe{sub 2}O{sub 3} on Fe{sup 0} metal can replace conventional particulate iron catalysts in Fenton-like processes. - Abstract: Iron oxide nanotubes (INT) were fabricated with potentiostatic anodization of zero valent iron foil in 1 M Na{sub 2}SO{sub 4} containing 0.5 wt% NH{sub 4}F electrolyte, holding the potential at 20, 40, and 60 V for 20 min, respectively. Field emission scanning electron microscopy and X-ray diffractometry were used to evaluate the morphology and crystalline structure of the INT film. The potential of 40 V for 20 min was observed to be optimal to produce an optimal catalytic film. Cyanide dissolved in water was degraded through the Fenton-like reaction using the INT film with hydrogen peroxide (H{sub 2}O{sub 2}). In case of INT-40 V in the presence of H{sub 2}O{sub 2} 3%, the first-order rate constant was found to be 1.7 × 10{sup −2} min{sup −1}, and 1.2 × 10{sup −2} min{sup −1} with commercial hematite powder. Degradation of cyanide was much less with only H{sub 2}O{sub 2}. Therefore, this process proposed in this work can be an excellent alternative to traditional catalysts for Fenton-like reaction.

  20. Interface/border trap characterization of Al2O3/AlN/GaN metal-oxide-semiconductor structures with an AlN interfacial layer

    International Nuclear Information System (INIS)

    We report the interface characterization of Al2O3/AlN/GaN MOS (metal-oxide-semiconductor) structures with an AlN interfacial layer. A thin monocrystal-like interfacial layer (AlN) is formed at the Al2O3/GaN to effectively block oxygen from the GaN surface and prevent the formation of detrimental Ga-O bonds. The suppression of Ga-O bonds is validated by X-ray photoelectron spectroscopy of the critical interface. Frequency-dispersion in C-V characteristics has been significantly reduced, owing to improved interface quality. Furthermore, using the conventional conductance method suitable for extracting the interface trap density Dit in MOS structures, Dit in the device with AlN was determined to be in the range of 1011–1012 eV−1 cm−2, showing one order of magnitude lower than that without AlN. Border traps near the gate-dielectric/GaN interface were identified and shown to be suppressed by the AlN interfacial layer as well

  1. Microscale X-ray tomographic investigation of the interfacial morphology between the catalyst and micro porous layers in proton exchange membrane fuel cells

    Science.gov (United States)

    Prass, Sebastian; Hasanpour, Sadegh; Sow, Pradeep Kumar; Phillion, André B.; Mérida, Walter

    2016-07-01

    The interfacial morphology between the catalyst layer (CL) and micro porous layer (MPL) influences the performance of proton exchange membrane fuel cells (PEMFCs). Here we report a direct method to investigate the CL-MPL interfacial morphology of stacked and compressed gas diffusion layer (GDL with MPL)-catalyst coated membrane (CCM) assemblies. The area, origin and dimensions of interfacial gaps are studied with high-resolution X-ray micro computed tomography (X-μCT). The projected gap area (fraction of the CL-MPL interface separated by gaps) is higher for GDL-CCM assemblies with large differences in the surface roughness between CL and MPL but reduces with increasing compression and similarity in roughness. Relatively large continuous gaps are found in proximity to cracks in the MPL. These are hypothesized to form due to the presence of large pores on the surface of the GDL. Smaller gaps are induced by the surface roughness features throughout the CL-MPL interface. By modification of the pore sizes on the GDL surface serving as substrate for the MPL, the number and dimension of MPL crack induced gaps can be manipulated. Moreover, adjusting the CL and MPL surface roughness parameters to achieve similar orders of roughness can improve the surface mating characteristics of these two components.

  2. Growth of multioxide planar film with the nanoscale inner structure via anodizing Al/Ta layers on Si

    International Nuclear Information System (INIS)

    An Al/Ta bilayer specimen prepared by a successive sputter-deposition of a 150-nm tantalum layer and a 180-nm aluminium layer onto a silicon wafer is anodically processed in a sequence of steps in oxalic acid electrolytes, at voltages of up to 53 V, which generates a 260-nm alumina film with well-ordered nanoporous structure. Further potentiodynamic reanodizing the specimen to 220 V causes the simultaneous growth of a 65-nm tantalum oxide layer beneath the alumina film and an array of oxide 'nanocolumns' (∼50 mn wide, ∼80 nm apart, ∼7 x 109 cm-2 population density) penetrating the alumina pores and reaching precisely to the top of the alumina film. The complete filling of the alumina pores is assisted by the high Pilling-Bedworth ratio for Ta/Ta2O5 and a substantially increased transport number for tantalum species (0.4), which is an average value of all migrating tantalum ions with different oxidation states. The nanocolumns are shown to be composed of a unique, regular mixture of Ta2O5 (dominating amount), suboxides TaO2 and TaOx (0.5 2O3, metallic Ta and Al aggregates, tantalum diboride (TaB2) and oxidized boron from the electrolyte. The ionic transport processes determining the self-organized growth of these planar oxide nanostructures are considered and described conceptually

  3. The effect of dye-sensitized solar cell based on the composite layer by anodic TiO2 nanotubes

    Science.gov (United States)

    Yang, Jun Hyuk; Kim, Kyung Hwan; Bark, Chung Wung; Choi, Hyung Wook

    2014-12-01

    TiO2 nanotube arrays are very attractive for dye-sensitized solar cells (DSSCs) owing to their superior charge percolation and slower charge recombination. Highly ordered, vertically aligned TiO2 nanotube arrays have been fabricated by a three-step anodization process. Although the use of a one-dimensional structure provides an enhanced photoelectrical performance, the smaller surface area reduces the adsorption of dye on the TiO2 surface. To overcome this problem, we investigated the effect of DSSCs constructed with a multilayer photoelectrode made of TiO2 nanoparticles and TiO2 nanotube arrays. We fabricated the novel multilayer photoelectrode via a layer-by-layer assembly process and thoroughly investigated the effect of various structures on the sample efficiency. The DSSC with a four-layer photoelectrode exhibited a maximum conversion efficiency of 7.22% because of effective electron transport and enhanced adsorption of dye on the TiO2 surface.

  4. Effects of the Molybdenum Oxide/Metal Anode Interfaces on Inverted Polymer Solar Cells

    International Nuclear Information System (INIS)

    Inverted polymer solar cells with molybdenum oxide (MoO3) as an anode buffer layer and different metals (Al or Ag) as anodes are studied. It is found that the inverted cell with a top Ag anode demonstrates enhanced charge collection and higher power conversion efficiency (PCE) compared to the cell with a top Al anode. An 18% increment of PCE is obtained by replacing Al with Ag as the top anode. Further studies show that an interfacial dipole pointing from MoO3 to Al is formed at MoO3/Al interfaces due to electron transfer from Al to MoO3 while this phenomenon cannot be observed at MoO3/Ag interfaces. It is speculated that the electric field at the MoO3/Al interface would hinder hole extraction, and hence reduce the short-circuit current

  5. Surface Passivation of MoO3 Nanorods by Atomic Layer Deposition Towards High Rate Durable Li Ion Battery Anodes

    KAUST Repository

    Ahmed, Bilal

    2015-06-03

    We demonstrate an effective strategy to overcome the degradation of MoO3 nanorod anodes in Lithium (Li) ion batteries at high rate cycling. This is achieved by conformal nanoscale surface passivation of the MoO3 nanorods by HfO2 using atomic layer deposition (ALD). At high current density such as 1500 mA/g, the specific capacity of HfO2 coated MoO3 electrodes is 68% higher than bare MoO3 electrodes after 50 charge/discharge cycles. After 50 charge/discharge cycles, HfO2 coated MoO3 electrodes exhibited specific capacity of 657 mAh/g, on the other hand, bare MoO3 showed only 460 mAh/g. Furthermore, we observed that HfO2 coated MoO3 electrodes tend to stabilize faster than bare MoO3 electrodes because nanoscale HfO2 layer prevents structural degradation of MoO3 nanorods. Additionally, the growth temperature of MoO3 nanorods and the effect of HfO2 layer thickness was studied and found to be important parameters for optimum battery performance. The growth temperature defines the microstructural features and HfO2 layer thickness defines the diffusion coefficient of Li–ions through the passivation layer to the active material. Furthermore, ex–situ HRTEM, X–ray photoelectron spectroscopy (XPS), Raman spectroscopy and X–ray diffraction was carried out to explain the capacity retention mechanism after HfO2 coating.

  6. A Synopsis of Interfacial Phenomena in Lithium-Based Polymer Electrolyte Electrochemical Cells

    Science.gov (United States)

    Baldwin, Richard S.; Bennett, William R.

    2007-01-01

    The interfacial regions between electrode materials, electrolytes and other cell components play key roles in the overall performance of lithium-based batteries. For cell chemistries employing lithium metal, lithium alloy or carbonaceous materials (i.e., lithium-ion cells) as anode materials, a "solid electrolyte interphase" (SEI) layer forms at the anode/electrolyte interface, and the properties of this "passivating" layer significantly affect the practical cell/battery quality and performance. A thin, ionically-conducting SEI on the electrode surface can beneficially reduce or eliminate undesirable side reactions between the electrode and the electrolyte, which can result in a degradation in cell performance. The properties and phenomena attributable to the interfacial regions existing at both anode and cathode surfaces can be characterized to a large extent by electrochemical impedance spectroscopy (EIS) and related techniques. The intention of the review herewith is to support the future development of lithium-based polymer electrolytes by providing a synopsis of interfacial phenomena that is associated with cell chemistries employing either lithium metal or carbonaceous "composite" electrode structures which are interfaced with polymer electrolytes (i.e., "solvent-free" as well as "plasticized" polymer-binary salt complexes and single ion-conducting polyelectrolytes). Potential approaches to overcoming poor cell performance attributable to interfacial effects are discussed.

  7. Analysis of chemical dissolution of the barrier layer of porous oxide on aluminum thin films using a re-anodizing technique

    International Nuclear Information System (INIS)

    Chemical dissolution of the barrier layer of porous oxide formed on thin aluminum films (99.9% purity) in the 4% oxalic acid after immersion in 2 mol dm-3 sulphuric acid at 50 deg. C has been studied. The barrier layer thickness before and after dissolution was calculated using a re-anodizing technique. It has been shown that above 57 V the change in the growth mechanism of porous alumina films takes place. As a result, the change in the amount of regions in the barrier oxide with different dissolution rates is observed. The barrier oxide contains two layers at 50 V: the outer layer with the highest dissolution rate and the inner layer with a low dissolution rate. Above 60 V the barrier oxide contains three layers: the outer layer with a high dissolution rate, the middle layer with the highest dissolution rate and the inner layer with a low dissolution rate. We suggest that the formation of the outer layer of barrier oxide with a high dissolution rate is linked with the injection of protons or H3O+ ions from the electrolyte into the oxide film at the anodizing voltages above 57 V

  8. Enhancement of electrochemical performance with Zn-Al-Bi layered hydrotalcites as anode material for Zn/Ni secondary battery

    International Nuclear Information System (INIS)

    Bi-doped Zn-Al layered double hydroxides (Zn-Al-Bi LDH) are prepared by the constant pH hydrothermal method and proposed as a novel anodic material in Zn/Ni secondary cells. The Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) images reveal that the as-prepared samples are well-crystallized and hexagon layer structure. The electrochemical performances of the Zn-Al-Bi LDH were analyzed by cyclic voltammetry, tafel plot, electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge tests. Compared with Zn-Al LDH, Zn-Al-Bi LDH with different Zn/Al/Bi molar rations, especially the sample of Zn/Al/Bi = 3:0.8:0.2 (molar ration) have higher discharge capacity and more stable cycling performances. Cyclic voltammograms clearly illuminated that the Zn-Al-Bi LDHs could decrease polarization, maintain the electrochemical activity, and enhance the discharge capacity of Zn-Al LDH. This battery can undergo at least 800 charge-discharge cycles at constant current of 1C without dendrite and short circuits. The discharge capacity of Zn-Al-Bi LDH after the 800th cycle remains about 380 mAh g−1 and the hexagonal crystal structure have no much changed after cycles

  9. Atomic/Molecular Layer Deposition of Lithium Terephthalate Thin Films as High Rate Capability Li-Ion Battery Anodes.

    Science.gov (United States)

    Nisula, Mikko; Karppinen, Maarit

    2016-02-10

    We demonstrate the fabrication of high-quality electrochemically active organic lithium electrode thin films by the currently strongly emerging combined atomic/molecular layer deposition (ALD/MLD) technique using lithium terephthalate, a recently found anode material for lithium-ion battery (LIB), as a proof-of-the-concept material. Our deposition process for Li-terephthalate is shown to well comply with the basic principles of ALD-type growth including the sequential self-saturated surface reactions, a necessity when aiming at micro-LIB devices with three-dimensional architectures. The as-deposited films are found crystalline across the deposition temperature range of 200-280 °C, which is a trait highly desired for an electrode material but rather unusual for hybrid inorganic-organic thin films. Excellent rate capability is ascertained for the Li-terephthalate films with no conductive additives required. The electrode performance can be further enhanced by depositing a thin protective LiPON solid-state electrolyte layer on top of Li-terephthalate; this yields highly stable structures with capacity retention of over 97% after 200 charge/discharge cycles at 3.2 C. PMID:26812433

  10. Radial microstructure and optical properties of a porous silicon layer by pulse anodic etching*

    Institute of Scientific and Technical Information of China (English)

    Long Yongfu

    2011-01-01

    This paper investigates the radial refractive index and optical and physical thicknesses of porous silicon (PS) layers prepared by pulse etching by means of reflectance spectroscopy, photoluminescence spectroscopy and scanning electron microscopy (SEM). The relationship between the radial refractive index and optical thickness of the PS sample and the position away from the etched centre along the radial direction has been analyzed in detail.With the position farther away from the etched centre, the SEM image shows that the physical thickness of the PS sample decreases slowly, whereas intensely decreases from 2.48 to 1.72 μm near the edge at a distance of 58 μm. Moreover, the radial refractive index increases, indicating that the porosity becomes smaller. Meanwhile, the reflectance spectra exhibit the less intense interference oscillations, which mean that the uniformity and interface smoothness of the PS layers become worse, and the envelope curves of photoluminescence spectra exhibit a trend of blue-shift, indicating a reduction in nanocrystal dimensions. The PS micro-cavity is prepared to study the radial optical properties of the PS layer, and the results verify that the uniformity and smoothness of the PS layer in the centre are better than those at the edge.

  11. Engineering of the energetic structure of the anode of organic photovoltaic devices utilizing hot-wire deposited transition metal oxide layers

    International Nuclear Information System (INIS)

    Graphical abstract: In this work we perform successful engineering of the anode of organic photovoltaics based on poly(3-hexylthiophene):[6,6]-phenyl butyric acid methyl ester blends by using metal oxide transport layers exhibiting shallow gap states which act as a barrier-free path for hole transport toward the anode. - Highlights: • Interface engineering of the anode. • Organic photovoltaics (OPVs). • Shallow gap states. • Barrier-free hole transport. • Design rules for interface engineering in OPVs. - Abstract: In this work we use hydrogen deposited molybdenum and tungsten oxides (chemically described as H:MOxx ≤ 3 where M = Mo or W) to control the energetics at the anode of bulk heterojunction (BHJ) organic photovoltaics (OPVs) based on poly(3-hexylthiophene):[6,6]-phenyl butyric acid methyl ester (P3HT:PC71BM) blends. Significantly improved current densities and open circuit voltages were achieved as a result of improved hole transport from the P3HT highest occupied molecular orbital (HOMO) toward indium tin oxide (ITO) anode. This was attributed to the formation of shallow gap states in these oxides which are located just below the Fermi level and above the polymer HOMO and thus may act as a barrier-free path for the extraction of holes. Consequently, these states can be used for controlling the energetic structure of the anode of OPVs. By using ultraviolet photoelectron spectroscopy it was found that dependent on the deposition conditions these gap states and work function of the metal oxides may be tailored to contribute to the precise alignment of the HOMO of the organic semiconductor (OSC) with the Fermi level of the anode electrode resulting in further enhancement of the device performance

  12. Engineering of the energetic structure of the anode of organic photovoltaic devices utilizing hot-wire deposited transition metal oxide layers

    Energy Technology Data Exchange (ETDEWEB)

    Vasilopoulou, M., E-mail: mariva@imel.demokritos.gr [Institute of Nanoscience and Nanotechnology, Department of Microelectronics, National Center for Scientific Research Demokritos, POB 60228, 15310 Agia Paraskevi, Attiki (Greece); Stathopoulos, N.A.; Savaidis, S.A. [Department of Electronics, Technological and Educational Institute (TEI) of Piraeus, Petrou Ralli & Thivon, 12244 Aegaleo (Greece); Kostis, I. [Institute of Nanoscience and Nanotechnology, Department of Microelectronics, National Center for Scientific Research Demokritos, POB 60228, 15310 Agia Paraskevi, Attiki (Greece); Department of Electronics, Technological and Educational Institute (TEI) of Piraeus, Petrou Ralli & Thivon, 12244 Aegaleo (Greece); Papadimitropoulos, G. [Institute of Nanoscience and Nanotechnology, Department of Microelectronics, National Center for Scientific Research Demokritos, POB 60228, 15310 Agia Paraskevi, Attiki (Greece); Davazoglou, D., E-mail: d.davazoglou@imel.demokritos.gr [Institute of Nanoscience and Nanotechnology, Department of Microelectronics, National Center for Scientific Research Demokritos, POB 60228, 15310 Agia Paraskevi, Attiki (Greece)

    2015-09-30

    Graphical abstract: In this work we perform successful engineering of the anode of organic photovoltaics based on poly(3-hexylthiophene):[6,6]-phenyl butyric acid methyl ester blends by using metal oxide transport layers exhibiting shallow gap states which act as a barrier-free path for hole transport toward the anode. - Highlights: • Interface engineering of the anode. • Organic photovoltaics (OPVs). • Shallow gap states. • Barrier-free hole transport. • Design rules for interface engineering in OPVs. - Abstract: In this work we use hydrogen deposited molybdenum and tungsten oxides (chemically described as H:MO{sub x}x ≤ 3 where M = Mo or W) to control the energetics at the anode of bulk heterojunction (BHJ) organic photovoltaics (OPVs) based on poly(3-hexylthiophene):[6,6]-phenyl butyric acid methyl ester (P3HT:PC{sub 71}BM) blends. Significantly improved current densities and open circuit voltages were achieved as a result of improved hole transport from the P3HT highest occupied molecular orbital (HOMO) toward indium tin oxide (ITO) anode. This was attributed to the formation of shallow gap states in these oxides which are located just below the Fermi level and above the polymer HOMO and thus may act as a barrier-free path for the extraction of holes. Consequently, these states can be used for controlling the energetic structure of the anode of OPVs. By using ultraviolet photoelectron spectroscopy it was found that dependent on the deposition conditions these gap states and work function of the metal oxides may be tailored to contribute to the precise alignment of the HOMO of the organic semiconductor (OSC) with the Fermi level of the anode electrode resulting in further enhancement of the device performance.

  13. Electric Interfacial Layer of Modified Cellulose Nanocrystals in Aqueous Electrolyte Solution: Predictions by the Molecular Theory of Solvation.

    Science.gov (United States)

    Lyubimova, Olga; Stoyanov, Stanislav R; Gusarov, Sergey; Kovalenko, Andriy

    2015-06-30

    The X-ray crystal structure-based models of Iα cellulose nanocrystals (CNC), both pristine and containing surface sulfate groups with negative charge 0-0.34 e/nm(2) produced by sulfuric acid hydrolysis of softwood pulp, feature a highly polarized "crystal-like" charge distribution. We perform sampling using molecular dynamics (MD) of the structural relaxation of neutral pristine and negatively charged sulfated CNC of various lengths in explicit water solvent and then employ the statistical mechanical 3D-RISM-KH molecular theory of solvation to evaluate the solvation structure and thermodynamics of the relaxed CNC in ambient aqueous NaCl solution at a concentration of 0.0-0.25 mol/kg. The MD sampling induces a right-hand twist in CNC and rearranges its initially ordered structure with a macrodipole of high-density charges at the opposite faces into small local spots of alternating charge at each face. This surface charge rearrangement observed for both neutral and charged CNC significantly affects the distribution of ions around CNC in aqueous electrolyte solution. The solvation free energy (SFE) of charged sulfated CNC has a minimum at a particular electrolyte concentration depending on the surface charge density, whereas the SFE of neutral CNC increases linearly with NaCl concentration. The SFE contribution from Na(+) counterions exhibits behavior similar to the NaCl concentration dependence of the whole SFE. An analysis of the 3D maps of Na(+) density distributions shows that these model CNC particles exhibit the behavior of charged nanocolloids in aqueous electrolyte solution: an increase in electrolyte concentration shrinks the electric interfacial layer and weakens the effective repulsion between charged CNC particles. The 3D-RISM-KH method readily treats solvent and electrolyte of a given nature and concentration to predict effective interactions between CNC particles in electrolyte solution. We provide CNC structural models and a modeling procedure for

  14. Performance enhancement of GaN metal–semiconductor–metal ultraviolet photodetectors by insertion of ultrathin interfacial HfO{sub 2} layer

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Manoj, E-mail: panwarm72@yahoo.com, E-mail: aokyay@ee.bilkent.edu.tr [UNAM-National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey); Tekcan, Burak; Okyay, Ali Kemal, E-mail: panwarm72@yahoo.com, E-mail: aokyay@ee.bilkent.edu.tr [UNAM-National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey and Department of Electrical and Electronics Engineering, Bilkent University, 06800 Ankara (Turkey)

    2015-03-15

    The authors demonstrate improved device performance of GaN metal–semiconductor–metal ultraviolet (UV) photodetectors (PDs) by ultrathin HfO{sub 2} (UT-HfO{sub 2}) layer on GaN. The UT-HfO{sub 2} interfacial layer is grown by atomic layer deposition. The dark current of the PDs with UT-HfO{sub 2} is significantly reduced by more than two orders of magnitude compared to those without HfO{sub 2} insertion. The photoresponsivity at 360 nm is as high as 1.42 A/W biased at 5 V. An excellent improvement in the performance of the devices is ascribed to allowed electron injection through UT-HfO{sub 2} on GaN interface under UV illumination, resulting in the photocurrent gain with fast response time.

  15. A comparative study regarding effects of interfacial ferroelectric Bi4Ti3O12 (BTO) layer on electrical characteristics of Au/-Si structures

    Indian Academy of Sciences (India)

    M Yildirim; M Gökçen

    2014-04-01

    Present study focuses on the effects of interfacial ferroelectric BTO layer on the electrical characteristics of Au/-Si structures, hence Au/-Si (MS) and Au/BTO/-Si (MFS) structures were fabricated and admittance measurements (capacitance–voltage: - and conductance–voltage: G/-) of both structures were conducted between 10 kHz and 1 MHz at room temperature. Results showed that - and G/- characteristics were affected not only by frequency but also through deposition of BTO layer. Some effects can be listed as sharper peaks in - plots, higher capacitance and conductance values. Structure’s series resistance (s) also decreased due to BTO layer. Interface states (ss) profiles of the structures were obtained using Hill–Coleman and high-low frequency capacitance (HF - LF). Some of the main electrical parameters were extracted from -2- plots using depletion capacitance approach. Furthermore, current–voltage characteristics of MS and MFS structures were presented.

  16. Influence of the Ti microstructure on anodic self-organized TiO2 nanotube layers produced in ethylene glycol electrolytes

    Science.gov (United States)

    Macak, J. M.; Jarosova, M.; Jäger, A.; Sopha, H.; Klementová, M.

    2016-05-01

    The relationship between the microstructure of Ti substrates and the anodic growth of self-organized TiO2 nanotube layers obtained upon their anodization in the ethylene glycol based electrolytes on these substrates is reported for the first time. Polished Ti sheets with mirror-like surface as well as unpolished Ti foils were considered in this work. Grains with a wide range of crystallographic orientations and sizes were revealed by Electron Backscatter Diffraction (EBSD) and correlated with nanotube growth on both types of substrates. A preferred grain orientation with [0 0 0 1] axis perpendicular to the surface was observed on all substrates. Surfaces of all substrates were anodized for 18 h in ethylene glycol electrolytes containing 88 mM NH4F and 1.5% water and thoroughly inspected by SEM. By a precise comparison of Ti substrates before and after anodization, the uniformity of produced self-organized TiO2 nanotube layers was evaluated in regard to the specific orientation of individual grains. Grains with [0 0 0 1] axis perpendicular to the surface turned out to be the most growth-promoting orientation on polished substrates. No orientation was found to be strictly growth-retarding, but sufficient anodization time (24 h) was needed to obtain uniform nanotube layers on all grains without remnant porous initial oxide. In contrast with polished Ti sheets, no specific orientation was found to significantly promote or retard the nanotube growth in the case of unpolished Ti foils. Finally, the difference between the average nanotube diameters of nanotubes grown on various grains was investigated showing non-negligible differences in the diameter for different grain orientations and substrates.

  17. Tuning the interfacial hole injection barrier between p-type organic materials and Co using a MoO3 buffer layer

    International Nuclear Information System (INIS)

    We demonstrate that the interfacial hole injection barrier Δh between p-type organic materials (i.e., CuPc and pentacene) and Co substrate can be tuned by the insertion of a MoO3 buffer layer. Using ultraviolet photoemission spectroscopy, it was found that the introduction of MoO3 buffer layer effectively reduces the hole injection barrier from 0.8 eV to 0.4 eV for the CuPc/Co interface, and from 1.0 eV to 0.4 eV for the pentacene/Co interface, respectively. In addition, by varying the thickness of the buffer, the tuning effect of Δh is shown to be independent of the thickness of MoO3 interlayer at both CuPc/Co and pentacene/Co interfaces. This Fermi level pinning effect can be explained by the integer charge-transfer model. Therefore, the MoO3 buffer layer has the potential to be applied in p-type organic spin valve devices to improve the device performance via reducing the interfacial hole injection barrier.

  18. GeOx interfacial layer scavenging remotely induced by metal electrode in metal/HfO2/GeOx/Ge capacitors

    Science.gov (United States)

    Lee, Taehoon; Jung, Yong Chan; Seong, Sejong; Lee, Sung Bo; Park, In-Sung; Ahn, Jinho

    2016-07-01

    The metal gate electrodes of Ni, W, and Pt have been investigated for their scavenging effect: a reduction of the GeOx interfacial layer (IL) between HfO2 dielectric and Ge substrate in metal/HfO2/GeOx/Ge capacitors. All the capacitors were fabricated using the same process except for the material used in the metal electrodes. Capacitance-voltage measurements, scanning transmission electron microscopy, and electron energy loss spectroscopy were conducted to confirm the scavenging of GeOx IL. Interestingly, these metals are observed to remotely scavenge the interfacial layer, reducing its thickness in the order of Ni, W, and then Pt. The capacitance equivalent thickness of these capacitors with Ni, W, and Pt electrodes are evaluated to be 2.7 nm, 3.0 nm, and 3.5 nm, and each final remnant physical thickness of GeOx IL layer is 1.1 nm 1.4 nm, and 1.9 nm, respectively. It is suggested that the scavenging effect induced by the metal electrodes is related to the concentration of oxygen vacancies generated by oxidation reaction at the metal/HfO2 interface.

  19. Engineering Interfacial Silicon Dioxide for Improved Metal-Insulator-Semiconductor Silicon Photoanode Water Splitting Performance.

    Science.gov (United States)

    Satterthwaite, Peter F; Scheuermann, Andrew G; Hurley, Paul K; Chidsey, Christopher E D; McIntyre, Paul C

    2016-05-25

    Silicon photoanodes protected by atomic layer deposited (ALD) TiO2 show promise as components of water splitting devices that may enable the large-scale production of solar fuels and chemicals. Minimizing the resistance of the oxide corrosion protection layer is essential for fabricating efficient devices with good fill factor. Recent literature reports have shown that the interfacial SiO2 layer, interposed between the protective ALD-TiO2 and the Si anode, acts as a tunnel oxide that limits hole conduction from the photoabsorbing substrate to the surface oxygen evolution catalyst. Herein, we report a significant reduction of bilayer resistance, achieved by forming stable, ultrathin (anodes were employed: (1) TiO2 deposition directly on an HF-etched Si(100) surface, (2) TiO2 deposition after SiO2 atomic layer deposition on an HF-etched Si(100) surface, and (3) oxygen scavenging, post-TiO2 deposition to decompose the SiO2 layer using a Ti overlayer. Each of these methods provides a progressively superior means of reliably thinning the interfacial SiO2 layer, enabling the fabrication of efficient and stable water oxidation silicon anodes. PMID:27096845

  20. Interfacial Characterizations of a Nickel-Phosphorus Layer Electrolessly Deposited on a Silane Compound-Modified Silicon Wafer Under Thermal Annealing

    Science.gov (United States)

    Lai, Kuei-Chang; Wu, Pei-Yu; Chen, Chih-Ming; Wei, Tzu-Chien; Wu, Chung-Han; Feng, Shien-Ping

    2016-06-01

    Front-side metallization of a Si wafer was carried out using electroless deposition of nickel-phosphorus (Ni-P) catalyzed by polyvinylpyrrolidone-capped palladium nanoclusters (PVP-nPd). A 3-[2-(2-Aminoethylamino)ethylamino] propyl-trimethoxysilane (ETAS) layer was covalently bonded on the Si surface as bridge linker to the Pd cores of PVP-nPd clusters for improving adhesion between the Ni-P layer and the Si surface. To investigate the effects of an interfacial ETAS layer on the Ni silicide formation at the Ni-P/Si contact, the Ni-P-coated Si samples were thermally annealed via rapid thermal annealing (RTA) from 500°C to 900°C for 2 min. To compare with the ETAS sample, the sputtered Ni layer on Si and electroless Ni-P layer on ion-Pd-catalyzed Si (both are standard processes) were also investigated. The microstructural characterizations for the Ni-P or Ni layer deposited on the Si wafer were performed using x-ray diffractometer, scanning electron microscopy, and transmission electron microscopy. Our results showed that the ETAS layer acted as a barrier to slow the atomic diffusion of Ni toward the Si side. Although the formation of Ni silicides required a higher annealing temperature, the adhesion strength and contact resistivity measurements of annealed Ni-P/Si contacts showed satisfactory results, which were essential to the device performance and reliability during thermal annealing.

  1. Engineered Interfacial and Configuration Design of Double Layered SnO2@TiO2-ZnO Nanoplates Ternary Heterostructures for Efficient Dye-Sensitized Solar Cells

    International Nuclear Information System (INIS)

    Highlights: • The 2D hierarchical ZnO nanoplates can be successfully fabricated via a facile sonochemical process. • The band-structure-matched hybrid ZnO-TiO2-SnO2 photoanodes were designed. • An overall power conversion efficiency of ∼6.37% was achieved for the SnO2@TiO2-ZnO nanoplates hybrid photoanodes with SnO2 blocking layer. - Abstract: The engineered interfacial and configuration design of anode materials plays pivotal role in photovoltaic performance of solar cells. Here we demonstrated a double layered SnO2@TiO2-ZnO nanoplates composite films on fluorine-doped tin oxide (FTO) substrate as photoanodes for high-performance dye-sensitized solar-cells (DSSCs). The results indicate that DSSCs based on double layered SnO2@TiO2-ZnO nanoplates composite film (∼5.55%) show an obvious 29.1% increase of power conversion efficiency as compared to the single layered SnO2@TiO2 nanoparticles photoelectrode with the same thickness of ∼18.5 μm. Intensity-modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) as well as electrochemical impedance spectra (EIS) measurements show that the double layered SnO2@TiO2-ZnO nanoplates film has faster electron transport rate and slower electron recombination rate than the SnO2@TiO2 one. Furthermore, final power conversion efficiency has been optimized to reach up ∼6.37% (Jsc of 17.18 mA cm−2, Voc of 742 mV and FF of 0.50) for the double layered SnO2@TiO2-ZnO nanoplates film photoanodes with the introduction of additional SnO2 blocking layer which would suppress the electron recombination between FTO glass and electrolyte. One of the specific advantages of the unique structure is the engineered integration of different promising materials, which made it possible to take full advantages of the superior dye adsorption, charge collection, charge transfer dynamics as well as optical scattering simultaneously. This study provides a scheme to selective combination of specific semiconductors metal oxides, namely, SnO2

  2. Electrochemical solar cells with layer-type semiconductor anodes Chemical treatments of the crystal surface

    Science.gov (United States)

    Razzini, G.; Peraldo Bicelli, L.; Pini, G.; Scrosati, B.

    1981-10-01

    Photoelectrochemical cells based on layer-type semiconductors (i.e., transition metal sulfides and selenides) have gained substantial interest due to their reasonably high solar efficiency and good stability against photocorrosion. However, the performance of this type of cell may be limited by irregularities in the semiconductor, since edges of the van der Waals surface exposed to the electrolyte may act as recombination centers. To control this effect, chemical surface treatments, based on specific agents which perform selectively on the transition metal atoms at the edge sites, have been studied. In particular, the effect of the disodium salt of the ethylene diamine tetracetic acid (EDTA) molecule (as well as that of many other organic molecules) on the performance of an n-MoSe2/ I(-), I2/Pt sample cell has been investigated. The treatment with EDTA generally improved both short-circuit current and power output, even if a considerable variation in the response from crystal to crystal was observed. The stability of the EDTA effect under prolonged cell operation was also examined.

  3. First-principles molecular dynamics study of the thermal stability of the BN, AlN, SiC and SiN interfacial layers in TiN-based heterostructures: Comparison with experiments

    International Nuclear Information System (INIS)

    We conducted first-principles molecular dynamics calculations of the stability and possible transformations of heterostructures consisting of face-centered-cubic (NaCl)-TiN(001) slabs with one monolayer thick pseudomorphically stabilized interfacial layer of B1-type BN, AlN, SiC and SiN, respectively. The calculations have been done with subsequent static relaxation of the heterostructures at temperatures between 0 and 1400 K. It is shown that: i) the BN interfacial layer forms a disordered h-BN-like structure consisting of BN3 units within the whole temperature range considered; ii) the B1-AlN interfacial layer is stable within the whole temperature range; iii) the B1-SiC interfacial layer transforms into a distorted 3C–SiC(111)-like phase above 600 K; and iv) the SiN interfacial layer consists of SiN4 and SiN6 units aligned along the [110] direction at room and high temperatures. Phonon calculations show that the observed modifications of the interfaces are due to the dynamical instability of the B1-type (001) and (111) interfacial layers of BN, SiC and SiN driven by soft modes within the given planes. The results, which can be understood also without the knowledge of the theoretical methods, were used to interpret the available experimental results on TiN-based heterostructures and nanocomposite coatings in order to provide guidance to the experimentalists for the preparation of better coatings. - Highlights: • First-principles quantum molecular dynamics studies were conducted. • TiN-based heterostructures with SiN, BN, AlN and SiC interfacial monolayers • Stability and structural transformation between 0 and 1400 K have been calculated. • The results of the calculations have been compared with experiments. • It is concluded which of the systems may form stable superhard nanocomposites

  4. Transport properties of interfacial Si-rich layers formed on silicate minerals during weathering: Implications for environmental concerns

    Science.gov (United States)

    Daval, Damien; Rémusat, Laurent; Bernard, Sylvain; Wild, Bastien; Micha, Jean-Sébastien; Rieutord, François; Fernandez-Martinez, Alejandro

    2015-04-01

    The dissolution of silicate minerals is of primary importance for various processes ranging from chemical weathering to CO2 sequestration. Whether it determines the rates of soil formation, CO2 uptake and its impact on climate change, channeling caused by hydrothermal circulation in reservoirs of geothermal power plants, durability of radioactive waste confinement glasses or geological sequestration of CO2, the same strategy is commonly applied for determining the long term evolution of fluid-rock interactions. This strategy relies on a bottom-up approach, where the kinetic rate laws governing silicate mineral dissolution are determined from laboratory experiments. However, a long-standing problem regarding this approach stems from the observation that laboratory-derived dissolution rates overestimate their field counterparts by orders of magnitude, casting doubt on the accuracy and relevance of predictions based on reactive-transport simulations. Recently [1], it has been suggested that taking into account the formation of amorphous Si-rich surface layers (ASSL) as a consequence of mineral dissolution may contribute to decrease the large gap existing between laboratory and natural rates. Our ongoing study is aimed at deciphering the extent to which ASSL may represent a protective entity which affects the dissolution rate of the underlying minerals, both physically (passivation) and chemically (by promoting the formation of a local chemical medium which significantly differs from that of the bulk solution). Our strategy relies on the nm-scale measurement of the physicochemical properties (diffusivity, thickness and density) of ASSL formed on cleavages of a model mineral (wollastonite) and their evolution as a function of reaction progress. Our preliminary results indicate that the diffusivity of nm-thick ASSL formed on wollastonite surface is ~1,000,000 times smaller than that reported for an aqueous medium, as estimated from the monitoring of the progression of a

  5. Low resistivity contact on n-type Ge using low work-function Yb with a thin TiO2 interfacial layer

    Science.gov (United States)

    Dev, Sachin; Remesh, Nayana; Rawal, Yaksh; Manik, Prashanth Paramahans; Wood, Bingxi; Lodha, Saurabh

    2016-03-01

    This work demonstrates the benefit of a lower contact barrier height, and hence reduced contact resistivity (ρc), using a low work-function metal (Yb) in unpinned metal-interfacial layer-semiconductor (MIS) contacts on n-type Ge. Fermi-level unpinning in MIS contacts on n-Ge is first established by introducing a 2 nm TiO2-x interfacial layer between various contact metals (Yb, Ti, Ni, Pt) and n-Ge. Further, Yb/TiO2-x/n-Ge MIS contact diodes exhibit higher current densities (up to 100×) and lower effective contact barrier height (up to 30%) versus Ti/TiO2-x control devices over a wide range of TiO2-x thickness (1-5 nm). Finally, low work-function Yb combined with doped TiO2-x having a low conduction band offset with Ge and high substrate doping (n+-Ge: 2.5 ×1019 cm-3) is shown to result in an ultra-low ρc value of 1.4 × 10-8 Ω cm2, 10 × lower than Ti/TiO2-x control devices.

  6. Photoelectrochemical Characterization of Sprayed α-Fe2O3 Thin Films: Influence of Si Doping and SnO2 Interfacial Layer

    Directory of Open Access Journals (Sweden)

    Yongqi Liang

    2008-01-01

    Full Text Available α-Fe2O3 thin film photoanodes for solar water splitting were prepared by spray pyrolysis of Fe(AcAc3. The donor density in the Fe2O3 films could be tuned between 1017–1020 cm-3 by doping with silicon. By depositing a 5 nm SnO2 interfacial layer between the Fe2O3 films and the transparent conducting substrates, both the reproducibility and the photocurrent can be enhanced. The effects of Si doping and the presence of the SnO2 interfacial layer were systematically studied. The highest photoresponse is obtained for Fe2O3 doped with 0.2% Si, resulting in a photocurrent of 0.37 mA/cm2 at 1.23 VRHE in a 1.0 M KOH solution under 80 mW/cm2 AM1.5 illumination.

  7. Greatly improved interfacial passivation of in-situ high κ dielectric deposition on freshly grown molecule beam epitaxy Ge epitaxial layer on Ge(100)

    Energy Technology Data Exchange (ETDEWEB)

    Chu, R. L. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Liu, Y. C.; Lee, W. C.; Huang, M. L.; Kwo, J., E-mail: raynien@phys.nthu.edu.tw, E-mail: mhong@phys.ntu.edu.tw [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Lin, T. D.; Hong, M., E-mail: raynien@phys.nthu.edu.tw, E-mail: mhong@phys.ntu.edu.tw [Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Pi, T. W. [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China)

    2014-05-19

    A high-quality high-κ/Ge interface has been achieved by combining molecule beam epitaxy grown Ge epitaxial layer and in-situ deposited high κ dielectric. The employment of Ge epitaxial layer has sucessfully buried and/or removed the residue of unfavorable carbon and native oxides on the chemically cleaned and ultra-high vacuum annealed Ge(100) wafer surface, as studied using angle-resolved x-ray photoelectron spectroscopy. Moreover, the scanning tunneling microscopy analyses showed the significant improvements in Ge surface roughness from 3.5 Å to 1 Å with the epi-layer growth. Thus, chemically cleaner, atomically more ordered, and morphologically smoother Ge surfaces were obtained for the subsquent deposition of high κ dielectrics, comparing with those substrates without Ge epi-layer. The capacitance-voltage (C-V) characteristics and low extracted interfacial trap density (D{sub it}) reveal the improved high-κ/Ge interface using the Ge epi-layer approach.

  8. Investigation on the Microstructure, Interfacial IMC Layer, and Mechanical Properties of Cu/Sn-0.7Cu-xNi/Cu Solder Joints

    Science.gov (United States)

    Yang, Li; Ge, Jinguo; Zhang, Yaocheng; Dai, Jun; Liu, Haixiang; Xiang, Jicen

    2016-04-01

    Sn-0.7Cu-xNi composite solder has been fabricated via mechanical mixing of different weight percentages of Ni particles with Sn-0.7Cu solder paste, and the effect of the Ni concentration on the microstructure, wettability, and tensile properties of Cu/Sn-0.7Cu-xNi/Cu solder joints investigated. The results show that refined dot-shaped particles of intermetallic compounds (IMCs) are uniformly dispersed in a primary β-Sn matrix in the Cu/Sn-0.7Cu-(0.05-0.1)Ni/Cu solder joints. The interfacial IMC layer thickness increased slightly when adding Ni content to 0.05 wt.%, then rapidly when further increasing the Ni concentration to 0.4 wt.%. Excellent wettability with bright appearance was obtained for the Sn-0.7Cu-0.05Ni solder due to diminished interfacial tension. The tensile properties improved after adding Ni content to 0.05 wt.% due to the presence of the refined dot-like IMC particles, in agreement with theoretical predictions based on the combination of dispersion and grain-refinement strengthening mechanisms. Refined microstructure and enhanced mechanical properties were obtained for the Cu/Sn-0.7Cu-0.05Ni/Cu solder joint.

  9. Temperature dependent interfacial and electrical characteristics during atomic layer deposition and annealing of HfO2 films in p-GaAs metal–oxide–semiconductor capacitors

    International Nuclear Information System (INIS)

    We have investigated the temperature dependent interfacial and electrical characteristics of p-GaAs metal–oxide–semiconductor capacitors during atomic layer deposition (ALD) and annealing of HfO2 using the tetrakis (ethylmethyl) amino hafnium precursor. The leakage current decreases with the increase of the ALD temperature and the lowest current is obtained at 300 °C as a result of the Frenkel-Poole conduction induced leakage current being greatly weakened by the reduction of interfacial oxides at the higher temperature. Post deposition annealing (PDA) at 500 °C after ALD at 300 °C leads to the lowest leakage current compared with other annealing temperatures. A pronounced reduction in As oxides during PDA at 500 °C has been observed using X-ray photoelectron spectroscopy at the interface resulting in a proportional increase in Ga2O3. The increment of Ga2O3 after PDA depends on the amount of residual As oxides after ALD. Thus, the ALD temperature plays an important role in determining the high-k/GaAs interface condition. Meanwhile, an optimum PDA temperature is essential for obtaining good dielectric properties. (paper)

  10. Structural and electrical characteristics of ALD-HfO2/n-Si gate stack with SiON interfacial layer for advanced CMOS technology

    Science.gov (United States)

    Gupta, Richa; Rajput, Renu; Prasher, Rakesh; Vaid, Rakesh

    2016-09-01

    We report the fabrication of an ultra-thin silicon oxynitride (SiON) as an interfacial layer (IL) for n-Si/ALD-HfO2 gate stack with reduced leakage current. The XRD, AFM, FTIR, FESEM and EDAX characterizations have been performed for structural and morphological studies. Electrical parameters such as dielectric constant (K), interface trap density (Dit), leakage current density (J), effective oxide charge (Qeff), barrier height (Φbo), ideality factor (ƞ), breakdown-voltage (Vbr) and series resistance (Rs) were extracted through C-V, G-V and I-V measurements. The determined values of K, Dit, J, Qeff, Φbo, ƞ, Vbr and Rs are 14.4, 0.5 × 10 11 eV-1 cm-2, 2.2 × 10-9 A/cm2, 0.3 × 1013 cm-2, 0.42, 2.1, -0.33 and 14.5 MΩ respectively. SiON growth prior to HfO2 deposition has curtailed the problem of high leakage current density and interfacial traps due to sufficient amount of N2 incorporated at the interface.

  11. HfO2 gate dielectric on Ge (1 1 1) with ultrathin nitride interfacial layer formed by rapid thermal NH3 treatment

    Science.gov (United States)

    Agrawal, Khushabu S.; Patil, Vilas S.; Khairnar, Anil G.; Mahajan, Ashok M.

    2016-02-01

    Interfacial properties of the ALD deposited HfO2 over the surface nitrided germanium substrate have been studied. The formation of GeON (∼1.7 nm) was confirmed by X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron spectroscopy (HRTEM) over the germanium surface. The effect of post deposition annealing temperature was investigated to study the interfacial and electrical properties of hafnium oxide/germanium oxynitride gate stacks. The high-k MOS devices with ultrathin GeON layer shows the good electrical characteristics including higher k value ∼18, smaller equivalent oxide thickness (EOT) around 1.5 nm and smaller hysteresis value less than 170 mV. The Qeff and Dit values are somewhat greater due to the (1 1 1) orientation of the germanium and may be due to the presence of nitrogen at the interface. The Fowler-Northeim (FN) tunneling of Ge MOS devices has been studied. The barrier height ΦB extracted from the plot is ∼1 eV.

  12. Temperature dependent interfacial and electrical characteristics during atomic layer deposition and annealing of HfO2 films in p-GaAs metal-oxide-semiconductor capacitors

    Science.gov (United States)

    Chen, Liu; Yuming, Zhang; Yimen, Zhang; Hongliang, Lü; Bin, Lu

    2015-12-01

    We have investigated the temperature dependent interfacial and electrical characteristics of p-GaAs metal-oxide-semiconductor capacitors during atomic layer deposition (ALD) and annealing of HfO2 using the tetrakis (ethylmethyl) amino hafnium precursor. The leakage current decreases with the increase of the ALD temperature and the lowest current is obtained at 300 °C as a result of the Frenkel-Poole conduction induced leakage current being greatly weakened by the reduction of interfacial oxides at the higher temperature. Post deposition annealing (PDA) at 500 °C after ALD at 300 °C leads to the lowest leakage current compared with other annealing temperatures. A pronounced reduction in As oxides during PDA at 500 °C has been observed using X-ray photoelectron spectroscopy at the interface resulting in a proportional increase in Ga2O3. The increment of Ga2O3 after PDA depends on the amount of residual As oxides after ALD. Thus, the ALD temperature plays an important role in determining the high-k/GaAs interface condition. Meanwhile, an optimum PDA temperature is essential for obtaining good dielectric properties. Project supported by the Advance Research Project of China (No. 5130803XXXX) and the National Natural Science Foundation of China (No. 61176070).

  13. Optimization of Residual Stresses in MMC's through Process Parameter Control and the use of Heterogeneous Compensating/Compliant Interfacial Layers. OPTCOMP2 User's Guide

    Science.gov (United States)

    Pindera, Marek-Jerzy; Salzar, Robert S.

    1996-01-01

    A user's guide for the computer program OPTCOMP2 is presented in this report. This program provides a capability to optimize the fabrication or service-induced residual stresses in unidirectional metal matrix composites subjected to combined thermomechanical axisymmetric loading by altering the processing history, as well as through the microstructural design of interfacial fiber coatings. The user specifies the initial architecture of the composite and the load history, with the constituent materials being elastic, plastic, viscoplastic, or as defined by the 'user-defined' constitutive model, in addition to the objective function and constraints, through a user-friendly data input interface. The optimization procedure is based on an efficient solution methodology for the inelastic response of a fiber/interface layer(s)/matrix concentric cylinder model where the interface layers can be either homogeneous or heterogeneous. The response of heterogeneous layers is modeled using Aboudi's three-dimensional method of cells micromechanics model. The commercial optimization package DOT is used for the nonlinear optimization problem. The solution methodology for the arbitrarily layered cylinder is based on the local-global stiffness matrix formulation and Mendelson's iterative technique of successive elastic solutions developed for elastoplastic boundary-value problems. The optimization algorithm employed in DOT is based on the method of feasible directions.

  14. Characterization of the interfacial properties between In-Bi solder and bulk Bi2212 with metallic precoating layers

    International Nuclear Information System (INIS)

    In this study, the Bi2212 superconductor and Cu-Ni metal were soldered with In-Bi alloy at low temperature. In order to improve the contact properties of the solder Cu/Ag precoating layers were applied on the surface of the superconductor by electroplating process. The shear strength of the contact was correlated with the electroplating current density and the Ag layer thickness. The strength increased as the electroplating current density and the Ag layer thickness increased. In the case of Cu/Ag multi-precoating, the contact strength was higher than that of the single Ag precoating layer case. The contact strength also increased when the Ag precoated layer was annealed at the temperature range of 500 deg. C due to better connectivity at the interface layers

  15. Manipulating Thermal Conductivity by Interfacial Modification of Misfit-Layered Cobaltites Ca3Co4O9

    Science.gov (United States)

    Fujii, Susumu; Yoshiya, Masato

    2016-03-01

    The phonon thermal conductivities of misfit-layered Ca3Co4O9, Sr3Co4O9, and Ba3Co4O9 were calculated using the perturbed molecular dynamics method to clarify the impact of lattice misfit on the phonon thermal conduction in misfit-layered cobaltites. Substitution of Sr and Ba for Ca substantially modified the magnitude of the lattice misfit between the CoO2 and rock salt (RS) layers, because of the different ionic radii, increasing overall phonon thermal conductivity. Further analyses with intentionally changed atomic masses of Ca, Sr, or Ba revealed that smaller ionic radius at the Ca site in the RS layer, instead of heavier atomic mass, is a critical factor suppressing the overall thermal conductivity of Ca3Co4O9, since it determines not only the magnitude of lattice misfit but also the dynamic interference between the two layers, which governs the phonon thermal conduction in the CoO2 and RS layers. This concept was demonstrated for Sr-doped Ca3Co4O9 as an example of atomistic manipulation for better thermoelectric properties. Phonon thermal conductivities not only in the RS layer but also in the CoO2 layer were reduced by the substitution of Sr for Ca. These results provide another strategy to improve the thermal conductivity of this class of misfit cobaltites, that is, to control the thermal conductivity of the CoO2 layer responsible for electronic and thermal conductivity by atomistic manipulation in the RS layer adjacent to the CoO2 layer.

  16. A highly active anode functional layer for solid oxide fuel cells based on proton-conducting electrolyte BaZr0.1Ce0.7Y0.2O3-δ

    Science.gov (United States)

    Zhang, Xiuling; Qiu, Yu'e.; Jin, Feng; Guo, Feng; Song, Yulan; Zhu, Baoyong

    2013-11-01

    Extensive works have been performed to diminish cathode polarization for proton-conducting electrolyte based solid oxide fuel cells (SOFCs) while not much attention is paid to functional anode for improving electrochemical reaction at three-phase-boundaries (TPB). In this work, a highly active anode functional layer (FL) synthesized by a modified combustion method was employed to significantly elevate the cell performance at intermediate operation temperatures (550-650 °C). The effects of anode structure configuration, FL powder size and thickness on power outputs and electrode polarization were investigated. A maximum power density of 489 mW cm-2 and a low electrode polarization resistance of 0.37 Ω cm2 were achieved at 650 °C, indicating fuel gas transport and hydrogen oxidation reaction at TPB sites largely contribute to total cell resistance which could be effectively diminished by optimization of anodic interface environment with the adoption of highly active anode powders.

  17. Effect of surface pretreatment on interfacial chemical bonding states of atomic layer deposited ZrO{sub 2} on AlGaN

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Gang; Arulkumaran, Subramaniam; Ng, Geok Ing; Li, Yang; Ang, Kian Siong [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Wang, Hong, E-mail: ewanghong@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore and CINTRA CNRS/NTU/Thales, UMI 3288, 50 Nanyang Drive, Singapore 637553 (Singapore); Ng, Serene Lay Geok; Ji, Rong [Data Storage Institute, Agency for Science Technology and Research (A-STAR), 5 Engineering Drive 1, Singapore 117608 (Singapore); Liu, Zhi Hong [Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, Singapore 138602 (Singapore)

    2015-09-15

    Atomic layer deposition (ALD) of ZrO{sub 2} on native oxide covered (untreated) and buffered oxide etchant (BOE) treated AlGaN surface was analyzed by utilizing x-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy. Evidenced by Ga–O and Al–O chemical bonds by XPS, parasitic oxidation during deposition is largely enhanced on BOE treated AlGaN surface. Due to the high reactivity of Al atoms, more prominent oxidation of Al atoms is observed, which leads to thicker interfacial layer formed on BOE treated surface. The results suggest that native oxide on AlGaN surface may serve as a protecting layer to inhibit the surface from further parasitic oxidation during ALD. The findings provide important process guidelines for the use of ALD ZrO{sub 2} and its pre-ALD surface treatments for high-k AlGaN/GaN metal–insulator–semiconductor high electron mobility transistors and other related device applications.

  18. Effect of surface pretreatment on interfacial chemical bonding states of atomic layer deposited ZrO2 on AlGaN

    International Nuclear Information System (INIS)

    Atomic layer deposition (ALD) of ZrO2 on native oxide covered (untreated) and buffered oxide etchant (BOE) treated AlGaN surface was analyzed by utilizing x-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy. Evidenced by Ga–O and Al–O chemical bonds by XPS, parasitic oxidation during deposition is largely enhanced on BOE treated AlGaN surface. Due to the high reactivity of Al atoms, more prominent oxidation of Al atoms is observed, which leads to thicker interfacial layer formed on BOE treated surface. The results suggest that native oxide on AlGaN surface may serve as a protecting layer to inhibit the surface from further parasitic oxidation during ALD. The findings provide important process guidelines for the use of ALD ZrO2 and its pre-ALD surface treatments for high-k AlGaN/GaN metal–insulator–semiconductor high electron mobility transistors and other related device applications

  19. Three-dimensional carbon nanotube-textile anode for high-performance microbial fuel cells.

    Science.gov (United States)

    Xie, Xing; Hu, Liangbing; Pasta, Mauro; Wells, George F; Kong, Desheng; Criddle, Craig S; Cui, Yi

    2011-01-12

    Microbial fuel cells (MFCs) harness the metabolism of microorganisms, converting chemical energy into electrical energy. Anode performance is an important factor limiting the power density of MFCs for practical application. Improving the anode design is thus important for enhancing the MFC performance, but only a little development has been reported. Here, we describe a biocompatible, highly conductive, two-scale porous anode fabricated from a carbon nanotube-textile (CNT-textile) composite for high-performance MFCs. The macroscale porous structure of the intertwined CNT-textile fibers creates an open 3D space for efficient substrate transport and internal colonization by a diverse microflora, resulting in a 10-fold-larger anolyte-biofilm-anode interfacial area than the projective surface area of the CNT-textile. The conformally coated microscale porous CNT layer displays strong interaction with the microbial biofilm, facilitating electron transfer from exoelectrogens to the CNT-textile anode. An MFC equipped with a CNT-textile anode has a 10-fold-lower charge-transfer resistance and achieves considerably better performance than one equipped with a traditional carbon cloth anode: the maximum current density is 157% higher, the maximum power density is 68% higher, and the energy recovery is 141% greater. PMID:21158405

  20. Three-Dimensional Carbon Nanotube−Textile Anode for High-Performance Microbial Fuel Cells

    KAUST Repository

    Xie, Xing

    2011-01-12

    Microbial fuel cells (MFCs) harness the metabolism of microorganisms, converting chemical energy into electrical energy. Anode performance is an important factor limiting the power density of MFCs for practical application. Improving the anode design is thus important for enhancing the MFC performance, but only a little development has been reported. Here, we describe a biocompatible, highly conductive, two-scale porous anode fabricated from a carbon nanotube-textile (CNT-textile) composite for high-performance MFCs. The macroscale porous structure of the intertwined CNT-textile fibers creates an open 3D space for efficient substrate transport and internal colonization by a diverse microflora, resulting in a 10-fold-larger anolyte-biofilm-anode interfacial area than the projective surface area of the CNT-textile. The conformally coated microscale porous CNT layer displays strong interaction with the microbial biofilm, facilitating electron transfer from exoelectrogens to the CNT-textile anode. An MFC equipped with a CNT-textile anode has a 10-fold-lower charge-transfer resistance and achieves considerably better performance than one equipped with a traditional carbon cloth anode: the maximum current density is 157% higher, the maximum power density is 68% higher, and the energy recovery is 141% greater. © 2011 American Chemical Society.

  1. Influence of a platinum functional layer on a Ni-Ce0.9Gd0.1O1.95 anode for thin-film solid oxide fuel cells

    International Nuclear Information System (INIS)

    A Pt functional layer was deposited between a Ni-Ce0.9Gd0.1O1.95 (50 wt. % Ni) anode and an 8 mol. % yttria-stabilized zirconia electrolyte in order to enhance the performance of a thin film solid oxide fuel cell. By inserting this ultrathin functional layer, the ohmic impedance of the single cell was significantly reduced, and the maximum power density was increased by a factor of ∼1.55. However, excessive deposition of the Pt functional layer caused ionic conduction pathway blocking between the yttria-stabilized zirconia and Ni-Gd0.1Ce0.9O1.95 (Ni-GDC), deactivating the Ni-GDC as a mixed ionic and electronic conducting anode. As a result, both the ohmic impedance and anodic faradaic impedance were increased after introduction of excessive Pt functional layer, and the maximum power density was also reduced

  2. Evolution mechanism of the interfacial reaction layers in the joints of diffusion bonded Mo and Ai foils

    Institute of Scientific and Technical Information of China (English)

    LI Jinglong; ZHAO Fengkuan; YANG Weihua; XIONG Jiangtao; ZHANG Fusheng; Lü Xuechao

    2009-01-01

    Mo foil (10-20 μm in thickness) and Al foil (20-60 μm in thickness) were vacuum diffusion bonded at 600-640 ℃ under 20 MPa for 54 min-6 h. The joints were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) to study the evolution mechanism of the reaction layers. The results show that Al atoms diffuse into Mo grain boundaries and form reaction products as Mo3Als, MoAl4, MoAl5 and MoAl12. The surface oxide film is eroded by the growths of the reaction products that plow into the lamellar texture of Mo grain boundaries. Mo3Al8 layer grows by "taking root" downwards and transforms into MoAl4 and MoAl5 phases upwards by absorbing Al atoms. MoAl12 layer grows up from MoAl5 layer in the same way. When the supplement of Al atoms ceases, MoAl12 transforms reversely into MoAl5 and MoAl3 into MoAl4 via the loss of Al atoms. However, MoAl4 continues to precipitate from Mo3Al8 layer. At last, there are MoAl4 and Mo3Al8 remained on the joint interface.

  3. Polyethylenimine Interfacial Layers in Inverted Organic Photovoltaic Devices: Effects of Ethoxylation and Molecular Weight on Efficiency and Temporal Stability.

    Science.gov (United States)

    Courtright, Brett A E; Jenekhe, Samson A

    2015-12-01

    We report a comparative study of polyethylenimine (PEI) and ethoxylated-polyethylenimine (PEIE) cathode buffer layers in high performance inverted organic photovoltaic devices. The work function of the indium-tin oxide (ITO)/zinc oxide (ZnO) cathode was reduced substantially (Δφ = 0.73-1.09 eV) as the molecular weight of PEI was varied from 800 g mol(-1) to 750 000 g mol(-1) compared with the observed much smaller reduction when using a PEIE thin film (Δφ = 0.56 eV). The reference inverted polymer solar cells based on the small band gap polymer PBDTT-FTTE (ITO/ZnO/PBDTT-FTTE:PC70BM/MoO3/Ag), without a cathode buffer layer, had an average power conversion efficiency (PCE) of 6.06 ± 0.22%. Incorporation of a PEIE cathode buffer layer in the same PBDTT-FTTE:PC70BM blend devices gave an enhanced performance with a PCE of 7.37 ± 0.53%. In contrast, an even greater photovoltaic efficiency with a PCE of 8.22 ± 0.10% was obtained in similar PBDTT-FTTE:PC70BM blend solar cells containing a PEI cathode buffer layer. The temporal stability of the inverted polymer solar cells was found to increase with increasing molecular weight of the cathode buffer layer. The results show that PEI is superior to PEIE as a cathode buffer layer in high performance organic photovoltaic devices and that the highest molecular weight PEI interlayer provides the highest temporal stability. PMID:26550983

  4. Transient analysis of carbon monoxide poisoning and oxygen bleeding in a PEM fuel cell anode catalyst layer

    Energy Technology Data Exchange (ETDEWEB)

    Zamel, Nada; Li, Xianguo [Department of Mechanical Engineering, University of Waterloo, Waterloo, Ont. (Canada)

    2008-02-15

    The presence of carbon monoxide in the fuel stream hinders the performance of a polymer electrolyte membrane (PEM) fuel cell, known as carbon monoxide (CO) poisoning. Introducing oxygen in the fuel stream lessens CO poisoning. Since CO poisoning is a phenomenon that occurs over a substantial period of time, a transient model has been developed in this study, taking into account the effect of CO concentration, operating pressure and temperature, as well as oxygen bleeding on the performance of the cell. It is found that at a lower CO concentration the poisoning effect takes a much longer time to reach the steady state, even though for a better steady state anode performance. A higher operating temperature results in a better steady state performance, but the performance drops faster toward the steady state value at higher temperature. A higher operating pressure leads to an enhanced performance over the entire transient history, although the benefit diminishes as pressure is increased. Even with a small amount of oxygen (0.5%) introduced into the fuel stream, the anode performance can be improved significantly. Finally, it is observed that the use of pure hydrogen interspersed in carbon monoxide containing fuel improves the anode performance. However, performance recovery when operating on pure hydrogen is much slower than the performance degradation due to the CO poisoning. (author)

  5. Highly ordered hexagonally arranged nanostructures on silicon through a self-assembled silicon-integrated porous anodic alumina masking layer

    International Nuclear Information System (INIS)

    A combined process of electrochemical formation of self-assembled porous anodic alumina thin films on a Si substrate and Si etching through the pores was used to fabricate ideally ordered nanostructures on the silicon surface with a long-range, two-dimensional arrangement in a hexagonal close-packed lattice. Pore arrangement in the alumina film was achieved without any pre-patterning of the film surface before anodization. Perfect pattern transfer was achieved by an initial dry etching step, followed by wet or electrochemical etching of Si at the pore bottoms. Anisotropic wet etching using tetramethyl ammonium hydroxide (TMAH) solution resulted in pits in the form of inverted pyramids, while electrochemical etching using a hydrofluoric acid (HF) solution resulted in concave nanopits in the form of semi-spheres. Nanopatterns with lateral size in the range 12-200 nm, depth in the range 50-300 nm and periodicity in the range 30-200 nm were achieved either on large Si areas or on pre-selected confined areas on the Si substrate. The pore size and periodicity were tuned by changing the electrolyte for porous anodic alumina formation and the alumina pore widening time. This parallel large-area nanopatterning technique shows significant potential for use in Si technology and devices.

  6. The effect of hydration layers on the anodic growth and on the dielectric properties of Al{sub 2}O{sub 3} for electrolytic capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Scaduto, G., E-mail: scaduto_giuseppe@libero.it [Electrochemical Material Science Laboratory, Facoltà di Ingegneria, Università di Palermo, Viale delle Scienze, Ed. 6, 90128 Palermo (Italy); Santamaria, M., E-mail: monica.santamaria@unipa.it [Electrochemical Material Science Laboratory, Facoltà di Ingegneria, Università di Palermo, Viale delle Scienze, Ed. 6, 90128 Palermo (Italy); Bocchetta, P., E-mail: patrizia.bocchetta@unisalento.it [Dipartimento di Ingegneria dell' Innovazione, Università del Salento, via Monteroni, 73100 Lecce (Italy); Di Quarto, F., E-mail: francesco.diquarto@unipa.it [Electrochemical Material Science Laboratory, Facoltà di Ingegneria, Università di Palermo, Viale delle Scienze, Ed. 6, 90128 Palermo (Italy)

    2014-01-01

    Hydrous films were grown on high purity and cubicity Al foils for electrolytic capacitors in deionized water, ethylene glycol–deionized water and glycerol–deionized water at different immersion times. According to X-ray diffraction patterns the hydration treatment allowed growing a pseudo boehmite layer on Al surface whose morphology is appreciably affected by the bath composition. Capacitance measurements and photoelectrochemical findings suggest that a more compact barrier layer forms during the immersion in alcohol containing solutions. The hydration in water allowed saving energy and preparing more blocking oxide films. The beneficial effect of hydration in hot water on the specific capacitance was evidenced only for films formed at 300 V due to the crystallization of amorphous alumina in γ′-Al{sub 2}O{sub 3}. - Highlights: • Hydrous films were grown on Al foils in hot H{sub 2}O and alcohol–H{sub 2}O mixtures. • Hydrous films' solid state properties were studied as a function of growing condition. • Hydrous films sensitively influence charge consumption during anodizing process. • Hydrous films sensitively influence dielectric properties of anodic Al{sub 2}O{sub 3}.

  7. The effect of hydration layers on the anodic growth and on the dielectric properties of Al2O3 for electrolytic capacitors

    International Nuclear Information System (INIS)

    Hydrous films were grown on high purity and cubicity Al foils for electrolytic capacitors in deionized water, ethylene glycol–deionized water and glycerol–deionized water at different immersion times. According to X-ray diffraction patterns the hydration treatment allowed growing a pseudo boehmite layer on Al surface whose morphology is appreciably affected by the bath composition. Capacitance measurements and photoelectrochemical findings suggest that a more compact barrier layer forms during the immersion in alcohol containing solutions. The hydration in water allowed saving energy and preparing more blocking oxide films. The beneficial effect of hydration in hot water on the specific capacitance was evidenced only for films formed at 300 V due to the crystallization of amorphous alumina in γ′-Al2O3. - Highlights: • Hydrous films were grown on Al foils in hot H2O and alcohol–H2O mixtures. • Hydrous films' solid state properties were studied as a function of growing condition. • Hydrous films sensitively influence charge consumption during anodizing process. • Hydrous films sensitively influence dielectric properties of anodic Al2O3

  8. Comparative Study of SiO2, Al2O3, and BeO Ultrathin Interfacial Barrier Layers in Si Metal-Oxide-Semiconductor Devices

    Directory of Open Access Journals (Sweden)

    J. H. Yum

    2012-01-01

    Full Text Available In a previous study, we have demonstrated that beryllium oxide (BeO film grown by atomic layer deposition (ALD on Si and III-V MOS devices has excellent electrical and physical characteristics. In this paper, we compare the electrical characteristics of inserting an ultrathin interfacial barrier layer such as SiO2, Al2O3, or BeO between the HfO2 gate dielectric and Si substrate in metal oxide semiconductor capacitors (MOSCAPs and n-channel inversion type metal oxide semiconductor field effect transistors (MOSFETs. Si MOSCAPs and MOSFETs with a BeO/HfO2 gate stack exhibited high performance and reliability characteristics, including a 34% improvement in drive current, slightly better reduction in subthreshold swing, 42% increase in effective electron mobility at an electric field of 1 MV/cm, slightly low equivalent oxide thickness, less stress-induced flat-band voltage shift, less stress induced leakage current, and less interface charge.

  9. Interfacial chemical reaction and multiple gap state formation on three layer cathode in organic light-emitting diode: Ca/BaF{sub 2}/Alq{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Gun; Kim, Jeong Won, E-mail: jeongwonk@kriss.re.kr [Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-ro, Daejeon 305-340 (Korea, Republic of); Korea University of Science and Technology (UST), 206 Gajeong-ro, Daejeon 305-350 (Korea, Republic of); Lee, Hyunbok [Department of Physics, Kangwon National University, 1 Gangwondaehak-gil, Chuncheon-si, Gangwon-do 200-701 (Korea, Republic of); Yi, Yeonjin [Institute of Physics and Applied Physics, Yonsei University, 50 Yonsei-ro, Seodaemoon-Gu, Seoul 120-749 (Korea, Republic of); Lee, Seung Mi [Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-ro, Daejeon 305-340 (Korea, Republic of)

    2015-07-14

    A three layer cathode is a promising stack structure for long lifetime and high efficiency in organic light-emitting diodes. The interfacial chemical reactions and their effects on electronic structures for alkaline-earth metal (Ca, Ba)/Alq{sub 3} [tris(8-hydroxyquinolinato)aluminum] and Ca/BaF{sub 2}/Alq{sub 3} are investigated using in-situ X-ray and ultraviolet photoelectron spectroscopy, as well as molecular model calculation. The BaF{sub 2} interlayer initially prevents direct contact between Alq{sub 3} and the reactive Ca metal, but it is dissociated into Ba and CaF{sub 2} by the addition of Ca. As the Ca thickness increases, the Ca penetrates the interlayer to directly participate in the reaction with the underlying Alq{sub 3}. This series of chemical reactions takes place irrespective of the BaF{sub 2} buffer layer thickness as long as the Ca overlayer thickness is sufficient. The interface reaction between the alkaline-earth metal and Alq{sub 3} generates two energetically separated gap states in a sequential manner. This phenomenon is explained by step-by-step charge transfer from the alkaline-earth metal to the lowest unoccupied molecular orbital states of Alq{sub 3}, forming new occupied states below the Fermi level.

  10. Interfacial chemical reaction and multiple gap state formation on three layer cathode in organic light-emitting diode: Ca/BaF2/Alq3

    International Nuclear Information System (INIS)

    A three layer cathode is a promising stack structure for long lifetime and high efficiency in organic light-emitting diodes. The interfacial chemical reactions and their effects on electronic structures for alkaline-earth metal (Ca, Ba)/Alq3 [tris(8-hydroxyquinolinato)aluminum] and Ca/BaF2/Alq3 are investigated using in-situ X-ray and ultraviolet photoelectron spectroscopy, as well as molecular model calculation. The BaF2 interlayer initially prevents direct contact between Alq3 and the reactive Ca metal, but it is dissociated into Ba and CaF2 by the addition of Ca. As the Ca thickness increases, the Ca penetrates the interlayer to directly participate in the reaction with the underlying Alq3. This series of chemical reactions takes place irrespective of the BaF2 buffer layer thickness as long as the Ca overlayer thickness is sufficient. The interface reaction between the alkaline-earth metal and Alq3 generates two energetically separated gap states in a sequential manner. This phenomenon is explained by step-by-step charge transfer from the alkaline-earth metal to the lowest unoccupied molecular orbital states of Alq3, forming new occupied states below the Fermi level

  11. A Novel Method to Determine the Thermal Conductivity of Interfacial Layers Surrounding the Nanoparticles of a Nanofluid

    OpenAIRE

    Rajinder Pal

    2014-01-01

    Nanofluids are becoming increasingly popular as heat transfer fluids in a variety of industrial applications, due to their enhanced heat transfer characteristics. The thermal conductivity of nanofluids is usually found to be much larger than that predicted from the classical models, such as the Maxwell model. The key mechanism of enhancement of thermal conductivity of dilute nanofluids is the solvation of nanoparticles with a layer of matrix liquid. As of now, little is known quantitatively a...

  12. Improved Performance of Organic Light-Emitting Field-Effect Transistors by Interfacial Modification of Hole-Transport Layer/Emission Layer: Incorporating Organic Heterojunctions.

    Science.gov (United States)

    Song, Li; Hu, Yongsheng; Zhang, Nan; Li, Yantao; Lin, Jie; Liu, Xingyuan

    2016-06-01

    Organic heterojunctions (OHJs) consisting of a strong electron acceptor 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HAT-CN) and an electron donor N,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine (NPB) were demonstrated for the first time that they can be implemented as effective modification layers between hole transport layer (HTL) and emission layer in the heterostructured organic light-emitting field effect transistors (OLEFETs). The influence of both HAT-CN/NPB junction (npJ) and NPB/HAT-CN junction (pnJ) on the optoelectronic performance of OLEFETs were conscientiously investigated. It is found that both the transport ability of holes and the injection ability of holes into emissive layer can be dramatically improved via the charge transfer of the OHJs and that between HAT-CN and the HTL. Consequently, OLEFETs with pnJ present optimal performance of an external quantum efficiency (EQE) of 3.3% at brightness of 2630 cdm(-2) and the ones with npJs show an EQE of 4.7% at brightness of 4620 cdm(-2). By further utilizing npn OHJs of HAT-CN/NPB/HAT-CN, superior optoelectronic performance with an EQE of 4.7% at brightness of 8350 cdm(-2) and on/off ratio of 1 × 10(5) is obtained. The results demonstrate the great practicality of implementing OHJs as effective modification layers in heterostructured OLEFETs. PMID:27215694

  13. Interfacial forces in aqueous media

    CERN Document Server

    van Oss, Carel J

    2006-01-01

    Thoroughly revised and reorganized, the second edition of Interfacial Forces in Aqueous Media examines the role of polar interfacial and noncovalent interactions among biological and nonbiological macromolecules as well as biopolymers, particles, surfaces, cells, and both polar and apolar polymers. The book encompasses Lifshitz-van der Waals and electrical double layer interactions, as well as Lewis acid-base interactions between colloidal entities in polar liquids such as water. New in this Edition: Four previously unpublished chapters comprising a new section on interfacial propertie

  14. Uniform carbon layer coated Mn3O4 nanorod anodes with improved reversible capacity and cyclic stability for lithium ion batteries.

    Science.gov (United States)

    Wang, Changbin; Yin, Longwei; Xiang, Dong; Qi, Yongxin

    2012-03-01

    A facile one-step solvothermal reaction route to large-scale synthesis of carbon homogeneously wrapped manganese oxide (Mn(3)O(4)@C) nanocomposites for anode materials of lithium ion batteries was developed using manganese acetate monohydrate and polyvinylpyrrolidone as precursors and reactants. The synthesized Mn(3)O(4)@C nanocomposites were characterized by X-ray diffraction, field-emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The synthesized tetragonal structured Mn(3)O(4) (space group I41/amd) samples display nanorodlike morphology, with a width of about 200-300 nm and a thickness of about 15-20 nm. It is shown that the carbon layers with a thickness of 5 nm are homogeneously coated on the Mn(3)O(4) nanorods. It is indicated from lithium storage capacity estimation that the Mn(3)O(4)@C samples display enhanced capacity retention on charge/discharge cycling. Even after 50 cycles, the products remains stable capacity of 473 mA h g(-1), which is as much 3.05 times as that of pure Mn(3)O(4) samples. Because of the low-cost, nonpollution, and stable capacity, the carbon homogeneously coated Mn(3)O(4)@C nanocomposites are promising anode material for lithium ion batteries. PMID:22394097

  15. Chemical compatibility issues related to use of copper as an interfacial layer for SiC fiber reinforced Ti3Ai+Nb composite

    Science.gov (United States)

    Misra, Ajay K.

    1991-01-01

    The reaction of Cu, a potential interfacial compliant layer for the Ti3Al plus Nb/SiC composite, with SiC, SCS-6 fiber, and the Ti3Al plus Nb matrix was examined at two temperatures: 1223 and 1273 K. Reaction of Cu with SiC resulted in the formation of a CuSi solution and free carbon, the reaction product being molten at 1273 K. Hot pressing the SCS-6 fiber in a Cu matrix at 1273 K resulted in cracking and delamination of the outer carbon-rich coating, thus allowing the Cu to penetrate to the SiC-carbon coating interface and react with SiC. In contrast, no such damage to the outer coating was observed at 1223 K. There was excessive reaction between Cu and the Ti3Al plus Nb matrix, the reaction product being molten both at 1223 and 1273 K. An interlayer of Nb between Cu and Ti3Al plus Nb matrix prevented the reaction between the two.

  16. Low interfacial trap density and high-temperature thermal stability in atomic layer deposited single crystal Y2O3/n-GaAs(001)

    Science.gov (United States)

    Lin, Yen-Hsun; Fu, Chien-Hua; Lin, Keng-Yung; Chen, Kuan-Hsiung; Chang, Tsong-Wen; Raynien Kwo, J.; Hong, Minghwei

    2016-08-01

    A low interfacial trap density (D it) of 2.2 × 1011 eV‑1 cm‑2 has been achieved with an atomic layer deposited (ALD) single crystal Y2O3 epitaxially on n-GaAs(001), along with a small frequency dispersion of 10.3% (2.6%/decade) at the accumulation region in the capacitance–voltage (C–V) curves. The D it and frequency dispersion in the C–V curves in this work are the lowest among all of the reported ALD-oxides on n-type GaAs(001). The D it was measured using the conductance–voltage (G–V) and quasi-static C–V (QSCV) methods. Moreover, the heterostructure was thermally stable with rapid annealing at 900 °C under various durations in He and N2, which has not been achieved in the heterostructures of ALD-Al2O3 or HfO2 on GaAs.

  17. Enhanced photoelectrochemical performance of WO{sub 3}/Ti photoanode due to in situ formation of a thin interfacial composite layer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Won Jae, E-mail: wjlee@keri.re.kr [Battery Research Center, Korea Electrotechnology Research Institute (KERI), Changwon 641-120 (Korea, Republic of); Shinde, Pravin S.; Go, Geun Ho; Doh, Chil Hoon [Battery Research Center, Korea Electrotechnology Research Institute (KERI), Changwon 641-120 (Korea, Republic of)

    2013-04-01

    Nanostructured WO{sub 3} thin films were prepared on titanium sheet substrates using a doctor blade technique. X-ray diffraction, Raman and field emission scanning electron microscopy studies revealed that the synthesized WO{sub 3} films are having monoclinic crystal structure, porous, polycrystalline with average grain size of ∼50 nm. The photoelectrochemical responses of WO{sub 3} films prepared on treated Ti sheets were recorded in 0.5 M H{sub 2}SO{sub 4} electrolyte under simulated 100 mW/cm{sup 2} illumination. WO{sub 3} film prepared on polished Ti sheet showed considerable enhancement in photocurrent as compared to WO{sub 3} films made on unpolished and pre-oxidized Ti sheets. These results suggest that in situ formation of a thin WO{sub x}–TiO{sub y} interfacial composite layer and improved adhesion of WO{sub 3} nanoparticles owing to increased reactive sites on polished Ti substrate play a significant role in enhancing the photoresponse. Such photoanodes are potential candidates in photoelectrochemical water splitting system for hydrogen generation.

  18. Electrochemical performance study of Ni/Ni-GDC double-layer anode-supported IT-SOFC%Ni/Ni-GDC双层阳极支撑型IT-SOFC性能研究

    Institute of Scientific and Technical Information of China (English)

    郭桂平; 彭开萍

    2015-01-01

    采用硝酸盐-柠檬酸溶胶-凝胶低温自蔓延燃烧法制备GDC粉末,用共压法制备了NiO-GDC单层阳极、NiO/NiO-GDC双层阳极及其单电池,并测试了其性能。研究结果表明:经H2还原后,Ni/Ni-GDC双层阳极外层为多孔结构,由粒径较大的Ni粒子团形成了稳定的电子电导通道及燃料通道;内层孔隙较小、较少,Ni均匀分布于GDC构成的支撑骨架中。Ni/Ni-GDC双层阳极的孔隙率及电导率都高于Ni-GDC单层阳极,从450~700℃,其电导率比Ni-GDC单层阳极都稳定高出15%~20%。单电池的测试结果表明:Ni/Ni-GDC双层阳极支撑单电池在700、650、600℃的最大功率密度分别为0.383、0.329、0.204 W/cm2,比Ni-GDC单层阳极支撑单电池分别高出了8.95%、79.38%、84.76%。Ni/Ni-GDC双层阳极支撑单电池具有比Ni-GDC单层阳极支撑单电池更高的中温、特别是低温电化学性能。%GDC electrolyte powder was synthesized by nitrate-citric acid sol-gel auto combustion method in low temperature. NiO-GDC single-layer anode, NiO/NiO-GDC double-layer anode and their single cells were prepared by co-pressing, then their properties were tested. The test results show that after reduction by H2, the outer layer of the Ni/Ni-GDC double-layer anode is porous and stable electronic conductivity channel and fuel channel is formed by the Ni particle groups with large size. In the inner layer, pores are less and smal er, and Ni particles distribute uniformly in the skeleton structure formed by GDC particle. Both the porosity and conductivity of Ni/Ni-GDC double-layer anode are higher than Ni-GDC single-layer anode; its conductivities from 450 to 700℃are al 15%~20%higher than Ni-GDC single-layer anode. The single celltest shows that the peak power densities of Ni/Ni-GDC double-layer anode-supported single cellat temperature 700, 650 and 600℃are respectively 0.383, 0.329 and 0.204 W/cm2, which are respectively 8.95%, 79.38%, 84

  19. Current-perpendicular-to-the-plane magnetoresistance from large interfacial spin-dependent scattering between Co50Fe50 magnetic layer and In-Zn-O conductive oxide spacer layer

    International Nuclear Information System (INIS)

    We have investigated electrically conductive indium-zinc-oxide (IZO) deposited by magnetron sputtering as spacer layer for current-perpendicular-to-the-plane giant magnetoresistance sensor devices. Spin-valves with a Co50Fe50/IZO/Co50Fe50 trilayer showed resistance-area product (RA) ranging from 110 to 250 mΩ μm2, significantly larger than all-metal structures with Ag or Cu spacers (∼40 mΩ μm2). Magnetoresistance ratios (ΔR/R) of 2.5% to 5.5% depending on the IZO spacer thickness (1.5–6.0 nm), corresponding to ΔRA values from 3 to 13 mΩ μm2, were obtained. The values of ΔRA with the IZO spacers and Co50Fe50 magnetic layers were significantly larger than those with conventional metal spacers and Co50Fe50 magnetic layers (∼1–2 mΩ μm2). The dependence of ΔRA on the magnetic layer thickness suggests that the larger ΔRA obtained with IZO spacer is due to a large interfacial spin-dependent scattering caused by the large specific resistance at the Co50Fe50/IZO interface. From structural characterization by TEM and the observed dependence of the RA dispersion on device size, the electric current flowing through the IZO spacer is thought to be laterally uniform, similar to normal metal spacers

  20. Current-perpendicular-to-the-plane magnetoresistance from large interfacial spin-dependent scattering between Co{sub 50}Fe{sub 50} magnetic layer and In-Zn-O conductive oxide spacer layer

    Energy Technology Data Exchange (ETDEWEB)

    Nakatani, T. M., E-mail: Tomoya.Nakatani@hgst.com; Childress, J. R. [San Jose Research Center, HGST, a Western Digital company, 3403 Yerba Buena Road, San Jose, California 95135 (United States)

    2015-06-28

    We have investigated electrically conductive indium-zinc-oxide (IZO) deposited by magnetron sputtering as spacer layer for current-perpendicular-to-the-plane giant magnetoresistance sensor devices. Spin-valves with a Co{sub 50}Fe{sub 50}/IZO/Co{sub 50}Fe{sub 50} trilayer showed resistance-area product (RA) ranging from 110 to 250 mΩ μm{sup 2}, significantly larger than all-metal structures with Ag or Cu spacers (∼40 mΩ μm{sup 2}). Magnetoresistance ratios (ΔR/R) of 2.5% to 5.5% depending on the IZO spacer thickness (1.5–6.0 nm), corresponding to ΔRA values from 3 to 13 mΩ μm{sup 2}, were obtained. The values of ΔRA with the IZO spacers and Co{sub 50}Fe{sub 50} magnetic layers were significantly larger than those with conventional metal spacers and Co{sub 50}Fe{sub 50} magnetic layers (∼1–2 mΩ μm{sup 2}). The dependence of ΔRA on the magnetic layer thickness suggests that the larger ΔRA obtained with IZO spacer is due to a large interfacial spin-dependent scattering caused by the large specific resistance at the Co{sub 50}Fe{sub 50}/IZO interface. From structural characterization by TEM and the observed dependence of the RA dispersion on device size, the electric current flowing through the IZO spacer is thought to be laterally uniform, similar to normal metal spacers.

  1. Characterization of La0.995Ca0.005NbO4/Ni anode functional layer by electrophoretic deposition in a La0.995Ca0.005NbO4 electrolyte based PCFC

    DEFF Research Database (Denmark)

    Bozza, Francesco; Schafbauer, W.; Meulenberg, W.A.;

    2012-01-01

    and water. Selectivity in the composition of the deposited layer was analyzed as a function of the suspension compositions and deposition conditions. A quasi-symmetrical cell was produced by depositing La0.995Ca0.005NbO4 electrolyte layer on the anode layer by EPD, and by applying a porous La0.995Ca0......The Electrophoretic Deposition (EPD) technique has been applied to the preparation of a porous La0.995Ca0.005NbO4/Ni composite anode layer, deposited on a porous pre-sintered La0.995Ca0.005NbO4/Ni support. Powders of La0.995Ca0.005NbO4 and NiO were suspended in a solution of acetylacetone, iodine...

  2. Deposition of perpendicular c-axis oriented BaM thin films on (001) Al{sub 2}O{sub 3} substrates by introducing an interfacial BaM buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhiyong, E-mail: xzy831230@yahoo.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zhaoqing Science and Technology Center, Zhaoqing 526020 (China); Lan, Zhongwen; Sun, Ke; Yu, Zhong; Guo, Rongdi; Zhu, Guangwei; Huang, Xiaodong [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2013-11-15

    M-type barium ferrite (BaM) thin films with two different structures (single layered and double layered) were deposited on (001) Al{sub 2}O{sub 3} single crystal substrates using an RF magnetron sputtering system. The changes in the surface morphologies, crystallographic and magnetic properties of BaM thin films corresponding to the different structures and substrate temperatures (T{sub s}) were investigated in detail. The results indicated that the interfacial BaM buffer layer plays an important role in improving the crystallographic and magnetic properties of BaM thin films. The single layered BaM thin films deposited at T{sub s}=300 °C and T{sub s}=500 °C are both randomly c-axis oriented. Whereas, by introducing a thin BaM layer which acts as an interfacial buffer layer, an excellent perpendicular c-axis orientation with an epitaxial structure for the double layered BaM thin film was obtained. The c-axis dispersion angle (Δθ{sub c}) decreased to 0.49°, and the perpendicular squareness ratio increased to 0.85 for the double layered film. The mechanism for improving the perpendicular c-axis orientation with an interfacial BaM buffer layer was attributed to two reasons. One is a relative increase in the nucleation sites for perpendicularly oriented grains over the nucleation sites for in-plane and/or randomly oriented grains, and the other is the release of the stress that comes from the interface between BaM thin film and Al{sub 2}O{sub 3} substrate. - Highlights: • BaM thin films were deposited on (001) Al{sub 2}O{sub 3} substrates by RF magnetron sputtering. • Single layered and double layered BaM films deposited at different T{sub s} were studied. • The single layered films are both randomly c-axis oriented. • The double layered film is perpendicularly c-axis oriented with an epitaxial texture. • The mechanism is attributed to the change of nucleation sites and release of stress.

  3. Process for anodizing aluminum foil

    International Nuclear Information System (INIS)

    In an integrated process for the anodization of aluminum foil for electrolytic capacitors including the formation of a hydrous oxide layer on the foil prior to anodization and stabilization of the foil in alkaline borax baths during anodization, the foil is electrochemically anodized in an aqueous solution of boric acid and 2 to 50 ppm phosphate having a pH of 4.0 to 6.0. The anodization is interrupted for stabilization by passing the foil through a bath containing the borax solution having a pH of 8.5 to 9.5 and a temperature above 800 C. and then reanodizing the foil. The process is useful in anodizing foil to a voltage of up to 760 V

  4. Influence of interfacial oxide on the optical properties of single layer CdTe/CdS quantum dots in porous silicon scaffolds

    International Nuclear Information System (INIS)

    Using a combination of continuous wave and time-resolved spectroscopy, we study the effects of interfacial conditions on the radiative lifetimes and photoluminescence intensities of sub-monolayer colloidal CdTe/CdS quantum dots (QDs) embedded in a three-dimensional porous silicon (PSi) scaffold. The PSi matrix was thermally oxidized under different conditions to change the interfacial oxide thickness. QDs embedded in a PSi matrix with ∼0.4 nm of interfacial oxide exhibited reduced photoluminescence intensity and nearly five times shorter radiative lifetimes (∼16 ns) compared to QDs immobilized within completely oxidized, porous silica (PSiO2) frameworks (∼78 ns). The exponential dependence of QD lifetime on interfacial oxide thickness in the PSi scaffolds suggests charge transfer plays an important role in the exciton dynamics

  5. Influence of interfacial oxide on the optical properties of single layer CdTe/CdS quantum dots in porous silicon scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Gaur, Girija; Fleetwood, Daniel M.; Weller, Robert A.; Reed, Robert A.; Weiss, Sharon M., E-mail: sharon.weiss@vanderbilt.edu [Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37212 (United States); Koktysh, Dmitry S. [Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee 37212 (United States); Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212 (United States)

    2015-08-10

    Using a combination of continuous wave and time-resolved spectroscopy, we study the effects of interfacial conditions on the radiative lifetimes and photoluminescence intensities of sub-monolayer colloidal CdTe/CdS quantum dots (QDs) embedded in a three-dimensional porous silicon (PSi) scaffold. The PSi matrix was thermally oxidized under different conditions to change the interfacial oxide thickness. QDs embedded in a PSi matrix with ∼0.4 nm of interfacial oxide exhibited reduced photoluminescence intensity and nearly five times shorter radiative lifetimes (∼16 ns) compared to QDs immobilized within completely oxidized, porous silica (PSiO{sub 2}) frameworks (∼78 ns). The exponential dependence of QD lifetime on interfacial oxide thickness in the PSi scaffolds suggests charge transfer plays an important role in the exciton dynamics.

  6. Impact of Copper-Doped Titanium Dioxide Interfacial Layers on the Interface-State and Electrical Properties of Si-based MOS Devices

    Science.gov (United States)

    Akin, Seçkİn; Sönmezoğlu, Savaş

    2015-09-01

    The current study presents the interface-state and electrical properties of silicon (Si)-based metal-oxide-semiconductor (MOS) devices using copper-doped titanium dioxide (Cu:TiO2) nanoparticles for possible applications as an interfacial layer in scaled high-k/metal gate MOSFET technology. The structural properties of the Cu:TiO2 nanoparticles have been obtained by means of X-ray diffraction (XRD), UV-Vis-NIR spectrometry, atomic force microscopy, and scanning electron microscopy measurements; they were compared with pure TiO2 thin film. With the incorporation of Cu, rutile-dominated anatase/rutile multiphase crystalline was revealed by XRD analysis. To understand the nature of this structure, the electronic parameters controlling the device performance were calculated using current-voltage ( I- V), capacitance-voltage ( C- V), and conductance-voltage ( G- V) measurements. The ideality factor ( n) was 1.21 for the Al/Cu:TiO2/ p-Si MOS device, while the barrier height ϕ b was 0.75 eV with semi-log I- V characteristics. This is in good agreement with 0.78 eV measured by the Norde model. Possible reasons for the deviation of the ideality factor from unity have been addressed. From the C- V measurements, the values of diffusion potential, barrier height, and carrier concentration were extracted as 0.67, 0.98 eV, and 8.73 × 1013 cm-3, respectively. Our results encourage further work to develop process steps that would allow the Cu-doped TiO2 film/Si interface to play a major role in microelectronic applications.

  7. Fabrication of thin silica layer-coated magnetite clusters (nFe3O4/silica) as anode materials for improved Li-ion batteries

    International Nuclear Information System (INIS)

    Thin silica layer-coated magnetite clusters (nFe3O4/silica) were prepared as active anode materials for Li-ion batteries. First, citrate-capped magnetites (C-Fe3O4) were synthesized by the co-precipitation method. Then, 3-aminopropyl trimethoxysilane (APTMS)-linked magnetite clusters (A-nFe3O4) were formed via electrostatic interactions between carboxylate groups of C-Fe3O4 and amine groups of APTMS, and the resulting A-nFe3O4 were heat-treated under N2 flow for 2 h. The calcined A-nFe3O4 at 500 °C exhibited the X-ray diffraction (XRD) patterns mostly attributed to fcc crystalline phases of Fe3O4, whereas the calcined C-Fe3O4 at 500 °C exhibited the XRD patterns attributed to the mixture of fcc crystalline phases of Fe3O4 and hexagonal crystalline phases of α-Fe2O3. The calcined A-nFe3O4 (i.e., nFe3O4/silica) exhibited the improved retention capacity by more than ca. 50% after 50 cycles as compared to the pristine iron oxides. The improved retention capacity of nFe3O4/silica was attributed to the enhanced chemical stability and large surface area of the thin silica layer-coated iron oxide clusters. - Highlights: • Thin silica layer-coated iron oxides (nFe3O4/silica) were facilely prepared. • The nFe3O4/silica exhibited the improved capacity retention by more than 50%. • Inert silica layer minimized the pulverization of iron oxide clusters

  8. Self-assembly surface modified indium-tin oxide anodes for single-layer light-emitting diodes

    CERN Document Server

    Morgado, J; Charas, A; Matos, M; Alcacer, L; Cacialli, F

    2003-01-01

    We study the effect of indium-tin oxide surface modification by self assembling of highly polar molecules on the performance of single-layer light-emitting diodes (LEDs) fabricated with polyfluorene blends and aluminium cathodes. We find that the efficiency and light-output of such LEDs is comparable to, and sometimes better than, the values obtained for LEDs incorporating a hole injection layer of poly(3,4-ethylene dioxythiophene) doped with polystyrene sulphonic acid. This effect is attributed to the dipole-induced work function modification of indium-tin oxide.

  9. Adhesion-enhanced thick copper film deposition on aluminum oxide by an ion-beam-mixed Al seed layer

    International Nuclear Information System (INIS)

    We report a highly-adherent 30-μm Cu conductive-path coating on an aluminum-oxide layer anodized on an aluminum-alloy substrate for a metal-printed circuit-board application. A 50-nm Al layer was first coated with an e-beam evaporative deposition method on the anodized oxide, followed by ion bombardment to mix the interfacial region. Subsequently, a Cu coating was deposited onto the mixed seed layer to the designed thickness. Adhesions of the interface were tested by using tape adhesion test, and pull-off tests and showed commercially acceptable adhesions for such thick coating layers. The ion beam mixing (IBM) plays the role of fastening the thin seed coating layer to the substrate and enhancing the adhesion of the Cu conductive path on the anodized aluminum surface.

  10. Anodic oxidation

    CERN Document Server

    Ross, Sidney D; Rudd, Eric J; Blomquist, Alfred T; Wasserman, Harry H

    2013-01-01

    Anodic Oxidation covers the application of the concept, principles, and methods of electrochemistry to organic reactions. This book is composed of two parts encompassing 12 chapters that consider the mechanism of anodic oxidation. Part I surveys the theory and methods of electrochemistry as applied to organic reactions. These parts also present the mathematical equations to describe the kinetics of electrode reactions using both polarographic and steady-state conditions. Part II examines the anodic oxidation of organic substrates by the functional group initially attacked. This part particular

  11. Direct sub-nanometer scale electron microscopy analysis of anion incorporation to self-ordered anodic alumina layers

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Rovira, L.; Lopez-Haro, M.; Hungria, A.B.; El Amrani, K. [Department of Materials Science and Metallurgical Engineering and Inorganic Chemistry, University of Cadiz, Republica Saharaui s/n, 11510 Puerto Real, Cadiz (Spain); Sanchez-Amaya, J.M. [Titania, Ensayos y Proyectos Industriales, S.L. Parque Tecnobahia, Edificio RETSE, Nave 4, 11500 El Puerto de Santa Maria (Cadiz) (Spain); Calvino, J.J. [Department of Materials Science and Metallurgical Engineering and Inorganic Chemistry, University of Cadiz, Republica Saharaui s/n, 11510 Puerto Real, Cadiz (Spain); Botana, F.J., E-mail: javier.botana@uca.e [Department of Materials Science and Metallurgical Engineering and Inorganic Chemistry, University of Cadiz, Republica Saharaui s/n, 11510 Puerto Real, Cadiz (Spain)

    2010-11-15

    Research highlights: {yields} Morphological and chemical characterization at atomic scale of porous alumina layers anodised in ordered regimes. {yields} Characterization based on the use of FEG-SEM, STEM-HAADF, STEM-EELS and STEM-X-EDS. {yields} Nanoscale distribution of P-, C- and S-bearing species in the pore wall. - Abstract: Ordered porous alumina layers prepared by two-step anodising in phosphoric, oxalic and sulphuric acids have been characterized at sub-nanometer scale using electron microscopy techniques. FEG-SEM and STEM-HAADF images allowed estimating the pore size, cell wall and pore wall thicknesses of the layers. Nanoanalytical characterization has been performed by STEM-EELS and STEM-X-EDS. Detailed features of the spatial distribution of anions in the pore wall of the films have been obtained. Maximum concentration of P-species occurs, approximately, at the middle of the pore wall; adjacent to the pore for C-species, whereas the distribution of S-species appears to be uniform.

  12. Interfacial Fermi Loops from Interfacial Symmetries

    OpenAIRE

    Takahashi, Ryuji; Murakami, Shuichi

    2014-01-01

    We propose a concept of interfacial symmetries such as interfacial particle-hole symmetry and interfacial time-reversal symmetry, which appear in interfaces between two regions related to each other by particle-hole or time-reversal transformations. These symmetries result in novel dispersion of interface states. In particular for the interfacial particle-hole symmetry the gap closes along a loop ("Fermi loop") at the interface. We numerically demonstrate this for the Fu-Kane-Mele tight-bindi...

  13. Sustainable Redox Mediation for Lithium-Oxygen Batteries by a Composite Protective Layer on the Lithium-Metal Anode.

    Science.gov (United States)

    Lee, Dong Jin; Lee, Hongkyung; Kim, Yun-Jung; Park, Jung-Ki; Kim, Hee-Tak

    2016-02-01

    A synergic combination of a soluble -redox mediator and a protected Li metal -electrode to prevent the self-discharge of the redox mediator is realized by -exploiting a 2,2,6,6-tetramethylpiperidinyl 1-oxyl (TEMPO) redox mediator and an Al2 O3 /PVdF-HFP composite -protective layer (CPL). Stabilization of Li metal by simple CPL coating is effective at -suppressing the chemical reduction of the oxidized TEMPO and opens up the possibility of sustainable redox mediation for robust cycling of Li-O2 batteries. PMID:26627981

  14. Influence of a platinum functional layer on a Ni-Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} anode for thin-film solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sungmin; Cha, Suk Won, E-mail: ybkim@hanyang.ac.kr, E-mail: swcha@snu.ac.kr [Department of Mechanical and Aerospace Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Chang, Ikwhang [Graduate School of Convergence Science and Technology, Seoul National University, 864-1, Iui-dong, Yeongtong-gu, Suwon, Gyeonggi-do 443-270 (Korea, Republic of); Kim, Young-Beom, E-mail: ybkim@hanyang.ac.kr, E-mail: swcha@snu.ac.kr [Department of Mechanical Engineering, Hanyang University, 222 Wangshimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

    2015-09-15

    A Pt functional layer was deposited between a Ni-Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} (50 wt. % Ni) anode and an 8 mol. % yttria-stabilized zirconia electrolyte in order to enhance the performance of a thin film solid oxide fuel cell. By inserting this ultrathin functional layer, the ohmic impedance of the single cell was significantly reduced, and the maximum power density was increased by a factor of ∼1.55. However, excessive deposition of the Pt functional layer caused ionic conduction pathway blocking between the yttria-stabilized zirconia and Ni-Gd{sub 0.1}Ce{sub 0.9}O{sub 1.95} (Ni-GDC), deactivating the Ni-GDC as a mixed ionic and electronic conducting anode. As a result, both the ohmic impedance and anodic faradaic impedance were increased after introduction of excessive Pt functional layer, and the maximum power density was also reduced.

  15. A novel radial anode layer ion source for inner wall pipe coating and materials modification--hydrogenated diamond-like carbon coatings from butane gas.

    Science.gov (United States)

    Murmu, Peter P; Markwitz, Andreas; Suschke, Konrad; Futter, John

    2014-08-01

    We report a new ion source development for inner wall pipe coating and materials modification. The ion source deposits coatings simultaneously in a 360° radial geometry and can be used to coat inner walls of pipelines by simply moving the ion source in the pipe. Rotating parts are not required, making the source ideal for rough environments and minimizing maintenance and replacements of parts. First results are reported for diamond-like carbon (DLC) coatings on Si and stainless steel substrates deposited using a novel 360° ion source design. The ion source operates with permanent magnets and uses a single power supply for the anode voltage and ion acceleration up to 10 kV. Butane (C4H10) gas is used to coat the inner wall of pipes with smooth and homogeneous DLC coatings with thicknesses up to 5 μm in a short time using a deposition rate of 70 ± 10 nm min(-1). Rutherford backscattering spectrometry results showed that DLC coatings contain hydrogen up to 30 ± 3% indicating deposition of hydrogenated DLC (a-C:H) coatings. Coatings with good adhesion are achieved when using a multiple energy implantation regime. Raman spectroscopy results suggest slightly larger disordered DLC layers when using low ion energy, indicating higher sp(3) bonds in DLC coatings. The results show that commercially interesting coatings can be achieved in short time. PMID:25173323

  16. Addition of sulfonated silicon dioxide on an anode catalyst layer to improve the performance of a self-humidifying proton exchange membrane fuel cell

    Science.gov (United States)

    Lin, Chien-Liang; Hsu, Shih-Chieh; Ho, Wei-Yu

    2016-03-01

    Sulfonated SiO2 was added on an anode catalyst layer to manufacture a hygroscopic electrode for self-humidifying proton exchange membrane fuel cells (PEMFCs). The inherent humidity of a proton exchange membrane (PEM) determines the electrical performance of PEMFCs. To maintain the high moisture content of the PEM, self-humidifying PEMFCs can use the water produced by the fuel cell reaction and, thus, do not require external humidification. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and water contact angle measurement tests were performed to characterize the structures and properties of sulfonated SiO2 and the related electrodes, and the electric current and voltage (I-V) performance curve tests for the fuel cells were conducted under differing gas humidification conditions. When 0.01mg/cm2 of sulfonated SiO2 was added, the electrical performance of the fuel cells (50∘C) increased 29% and 59% when the fuel cell reaction gases were humidified at 70∘C and 50∘C, respectively.

  17. Tunable Interfacial Thermal Conductance by Molecular Dynamics

    Science.gov (United States)

    Shen, Meng

    We study the mechanism of tunable heat transfer through interfaces between solids using a combination of non-equilibrium molecular dynamics simulation (NEMD), vibrational mode analysis and wave packet simulation. We investigate how heat transfer through interfaces is affected by factors including pressure, interfacial modulus, contact area and interfacial layer thickness, with an overreaching goal of developing fundamental knowledge that will allow one to tailor thermal properties of interfacial materials. The role of pressure and interfacial stiffness is unraveled by our studies on an epitaxial interface between two Lennard-Jones (LJ) crystals. The interfacial stiffness is varied by two different methods: (i) indirectly by applying pressure which due to anharmonic nature of bonding, increases interfacial stiffness, and (ii) directly by changing the interfacial bonding strength by varying the depth of the potential well of the LJ potential. When the interfacial bonding strength is low, quantitatively similar behavior to pressure tuning is observed when the interfacial thermal conductance is increased by directly varying the potential-well depth parameter of the LJ potential. By contrast, when the interfacial bonding strength is high, thermal conductance is almost pressure independent, and even slightly decreases with increasing pressure. This decrease can be explained by the change in overlap between the vibrational densities of states of the two crystalline materials. The role of contact area is studied by modeling structures comprised of Van der Waals junctions between single-walled nanotubes (SWCNT). Interfacial thermal conductance between SWCNTs is obtained from NEMD simulation as a function of crossing angle. In this case the junction conductance per unit area is essentially a constant. By contrast, interfacial thermal conductance between multiwalled carbon nanotubes (MWCNTs) is shown to increase with diameter of the nanotubes by recent experimental studies [1

  18. Effects of ozone post deposition treatment on interfacial and electrical characteristics of atomic-layer-deposited Al2O3 and HfO2 films on GaSb substrates

    International Nuclear Information System (INIS)

    Atomic-layer-deposited Al2O3 and HfO2 films on GaSb substrates were treated by in-situ ozone post deposition treatment (PDT). The effects of ozone PDT on the interfacial and electrical properties of Al2O3 and HfO2 gate dielectric films on GaSb substrates were investigated carefully. It is found that the dielectric quality and the interfacial properties of the Al2O3 and HfO2 films are improved by ozone PDT. After in-situ ozone PDT for 5 min, the Al2O3 and HfO2 films on GaSb substrates exhibit improved electrical and interfacial properties, such as reduced frequency dispersion, gate leakage current, border traps and interface traps. Interface trap density is reduced by ∼24% for the Al2O3/GaSb stacks and ∼27% for the HfO2/GaSb stacks. In-situ ozone PDT is proved to be a promising technique in improving the quality of high-k gate stacks on GaSb substrates.

  19. Analysis of the Deposit Layer from Electrolyte Side Reaction on the Anode of the Pouch Type Lithium Ion Polymer Batteries: The Effect of State of Charge and Charge Rate

    International Nuclear Information System (INIS)

    Highlights: • Raising the battery cycling potential increased the rate of side reaction. • Growth of deposit layer thickness at the electrode/electrolyte interface at high SOC. • A significant amount of lithium was consumed in forming the deposit layer. • Some of the lithium were “trapped” in the graphite after the discharge cycle. - Abstract: The formation of the solid electrolyte interface (SEI) layer on the surface of the anode electrode of a lithium ion battery prevents further electrolyte decomposition reaction. However, at certain battery operating conditions, the SEI breakdown leading to more electrolyte decomposition reactions that form several species on the anode electrode surface. This paper focuses on the effect of battery potential and charge rate on the decomposition side reaction on the anode electrode of a lithium ion polymer battery, as a result of the breakdown of the SEI layer. The results from this study indicate that raising the state of charge (SOC) increases the rate of the electrolyte decomposition side reaction that resulted in formation of a thick deposit layer at the electrolyte/electrolyte interface. This deposit layer contains lithium that can no longer participate in the reversible electrochemical reaction. In addition, at high cycling potential and charge rates the amount of lithium in the graphite after complete cell discharge increased due to the entrapment of lithium in the graphite. The amount of irreversible capacity loss for the batteries cycled at high potential and current correlates with the amount of trapped lithium in the graphite and the growth of the deposit layer thickness at the electrode/electrolyte interface

  20. Interfacial and near interfacial crack growth phenomena in metal bonded alumina

    Energy Technology Data Exchange (ETDEWEB)

    Kruzic, Jamie Joseph

    2002-03-01

    Metal/ceramic interfaces can be found in many engineering applications including microelectronic packaging, multi-layered films, coatings, joints, and composite materials. In order to design reliable engineering systems that contain metal/ceramic interfaces, a comprehensive understanding of interfacial and near interfacial failure mechanisms is necessary.

  1. Anodic bonded graphene

    OpenAIRE

    Balan, Adrian; Kumar, Rakesh; Boukhicha, Mohamed; Beyssac, Olivier; Bouillard, Jean-Claude; Taverna, Dario; Sacks, William; Marangolo, Massimiliano; Lacaze, Emmanuelle; Escoffier, Walter; Poumirol, Jean-Marie; Shukla, Abhay

    2010-01-01

    Abstract We show how to prepare graphene samples on a glass substrate with the anodic bonding method. In this method, a graphite precursor in flake form is bonded to a glass substrate with the help of an electrostatic field and then cleaved off to leave few layer graphene on the substrate. Now that several methods are available for producing graphene, the relevance of our method is in its simplicity and practicality for producing graphene samples of about 100 ?m lateral dimensions. This me...

  2. Effects of Interfacial Charges On Doped and Undoped HFOX Stack Layer with Tin Metal Gate Electrode For Nano-Scaled CMOS Generation

    Directory of Open Access Journals (Sweden)

    S. Chatterjee

    2011-01-01

    Full Text Available A comparison of the interfacial charges present in the high-k stacked gate dielectrics for Zr-doped HfOx and undoped HfOx samples with titanium nitride (TiN metal gate electrode is reported here. The metal gate work function value (4.31 eV for TiN gate electrode was extracted from the TiN/SiO2 /p-Si capacitor. The calculated charge densities in both doped and undoped films are of the order of 1012 cm – 2. The interfacial charge present in the high-k/SiO2 interface is negative for ALD deposited pure HfO2 samples; where as the charges are positive for RF-sputter deposited pure HfO2 and Zr-doped HfOx samples. The existence of positive interface charges may be due to the fabrication process.

  3. Role of interfacial carbon layer in the thermal diffusivity/conductivity of silicon carbide fiber-reinforced reaction-bonded silicon nitride matrix composites

    Science.gov (United States)

    Bhatt, Hemanshu; Donaldson, Kimberly Y.; Hasselman, D. P. H.; Bhatt, Ramakrishna T.

    1992-01-01

    Experiments were carried out on samples of reaction-bonded silicon nitride uniaxially reinforced by SiC monofilaments with and without a 3-micron-thick carbon-rich coating. It is found that a combination of a carbon coatings on the fibers and an interfacial gap due to the thermal expansion mismatch in the composite can significantly (by a factor of 2) lower the effective thermal diffusivity in the direction transverse to the fiber. At atmospheric pressure, gaseous conduction across the interfacial gap makes a significant contribution to the heat transfer across the interface, indicated by significantly lower values of the effective thermal diffusivity under vacuum than in nitrogen or helium at atmospheric pressure.

  4. A microfluidic-based bubble generation platform enables analysis of physical property change in phospholipid surfactant layers by interfacial ozone reaction†

    OpenAIRE

    Shin, Young Shik; Choi, Tae Su; Kim, Hyungjun; Beauchamp, J. L.; Heath, James R.; Kim, Hugh I.

    2012-01-01

    The air-liquid interface filled with pulmonary surfactant is a unique feature of our lung alveoli. The mechanical properties of this interface play an important role in breathing and its malfunction induced by an environmental hazard, such as ozone, relates to various lung diseases. In order to understand the interfacial physics of the pulmonary surfactant system, we employed a microfluidic bubble generation platform with a model pulmonary surfactant composed of two major phospholipids: DPPC ...

  5. Anodic bonded graphene

    Energy Technology Data Exchange (ETDEWEB)

    Balan, Adrian; Kumar, Rakesh; Boukhicha, Mohamed; Beyssac, Olivier; Bouillard, Jean-Claude; Taverna, Dario; Sacks, William; Shukla, Abhay [Universite Pierre et Marie Curie-Paris 6, CNRS-UMR7590, Institut de Mineralogie et de Physique des Milieux Condenses, 140 rue de Lourmel, Paris, F-75015 France (France); Marangolo, Massimiliano; Lacaze, Emanuelle; Gohler, Roger [Universite Pierre et Marie Curie-Paris 6, CNRS-UMR7588, Institut des Nanosciences de Paris, 140 rue de Lourmel, Paris, F-75015 France (France); Escoffier, Walter; Poumirol, Jean-Marie, E-mail: abhay.shukla@upmc.f [Laboratoire National des Champs Magnetiques Intenses, INSA UPS CNRS, UPR 3228, Universite de Toulouse, 143 avenue de Rangueil, 31400 Toulouse (France)

    2010-09-22

    We show how to prepare graphene samples on a glass substrate with the anodic bonding method. In this method, a graphite precursor in flake form is bonded to a glass substrate with the help of an electrostatic field and then cleaved off to leave few layer graphene on the substrate. Now that several methods are available for producing graphene, the relevance of our method is in its simplicity and practicality for producing graphene samples of about 100 {mu}m lateral dimensions. This method is also extensible to other layered materials. We discuss some detailed aspects of the fabrication and results from Raman spectroscopy, local probe microscopy and transport measurements on these samples.

  6. Interfacial reactions between PbO-rich glasses and aluminium composites

    CERN Document Server

    Ison, S J

    2000-01-01

    565 deg C occurs when dissolution rate exceeds oxidation rate, exposing the fresh Al anode to the glass melt. Under inert atmosphere (at 583 deg C), air oxidation is not possible and galvanic cell redox reactions generate an excessive copper interlayer as the system attempts to sustain the oxide layer at the anode. Similar behaviour is observed in those coatings formed on the alloy using glass C (containing Al sub 2 O sub 3 and Na sub 2 O). In this case, the interfacial reactions involve the PbO of the glass and Pb-rich spherical precipitates are formed in the interfacial region, along side sodium aluminosilicate phases, precipitated from the PbO-depleted glass. The behaviour in both systems indicates that oxygen diffuses through the edge of the glass drop, from the atmosphere, to the substrate/glass interface. Coatings formed on the MMCs in air exhibited a porosity of approx 10%, attributed to the production of CO sub 2 gas through the oxidation of SiC at the glass/MMC interface by oxygen diffusion from the ...

  7. Modeling of an anode-supported Ni-YSZ vertical stroke Ni-ScSZ vertical stroke ScSZ vertical stroke LSM-ScSZ multiple layers SOFC cell. Part I. Experiments, model development and validation

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Yixiang; Cai, Ningsheng; Li, Chen; Bao, Cheng [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Tsinghua University, Beijing 100084 (China); Croiset, Eric [Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Qian, Jiqin; Hu, Qiang; Wang, Shaorong [Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS), 1295 Dingxi Road, Shanghai 200050 (China)

    2007-10-11

    This paper is the first part of a two-part paper and presents the development, calibration and validation of a two-dimensional isothermal mechanistic model of a composite yttria/scandia-stabilized zirconia anode-supported multiple layers solid oxide fuel cell (Ni-YSZ vertical stroke Ni-ScSZ vertical stroke ScSZ vertical stroke LSM-ScSZ). This model was developed to describe the intricate interdependency among the ionic conduction, electronic conduction, multi-component species transport, electrochemical reaction processes and electrode microstructure for intermediate temperatures operation between 750 and 850 C. This model takes into account the fact that the electrochemical reactions take place throughout the electrodes and not only at the electrolyte/electrode boundaries. The model was calibrated using experimental polarization curves and then validated by comparing each cell component polarizations (anodic, cathodic and electrolyte) determined from the simulation and from specific experiments using a symmetric cell and EIS measurements. (author)

  8. Interfacial hydrodynamics: a microscopic approach

    OpenAIRE

    Baus, Marc; Fernández Tejero, Carlos

    1983-01-01

    Linearized hydrodynamic equations for a nonuniform anisotropic fluid are obtained from the exact Mori-Zwanzig equations for the conserved densities. In the particular case of a two-phase system with a planar equilibrium interface, these equations can be reduced to the ordinary hydrodynamic equations inside each bulk phase and to surface hydrodynamic equations for the interfacial layer. Surface transport coefficients and surface thermodynamic parameters are hereby obtained as Gibbs surface exc...

  9. Phase diagrams modified by interfacial penalties

    OpenAIRE

    Atanacković T.M.; Huo Y.; Jeličić Z.; Müller I.

    2007-01-01

    The conventional forms of phase diagrams are constructed without consideration of interfacial energies and they represent an impor­tant tool for chemical engineers and metallurgists. If interfacial energies are taken into consideration, it is intuitively obvious that the regions of phase equilibria must become smaller, because there is a penalty on the formation of interfaces. We investigate this phe­nomenon qualitatively for a one-dimensional model, in which the phases occur as layers rather...

  10. A comparative study on the electrical parameters of Au/n-Si Schottky diodes with and without interfacial (Ca1.9Pr0.1Co4Ox) layer

    Science.gov (United States)

    Kaya, A.; Çetinkaya, H. G.; Altındal, Ş.; Uslu, I.

    2016-05-01

    In order to compare the main electrical parameters such as ideality factor (n), barrier height (BH) (ΦI-V), series (Rs) and shunt (Rsh) resistances and energy density distribution profile of surface states (Nss), the Au/n-Si (MS) Schotthy diodes (SDs), with and without interfacial (Ca1.9Pr0.1Co4Ox) layer were obtained from the current-voltage (I-V ) measurements at room temperature. The other few electrical parameters such as Fermi energy level (EF), BH (ΦC-V), Rs and voltage dependence of Nss profile were also obtained from the capacitance-voltage (C-V ) measurements. The voltage dependence of Nss profile has two distinctive peaks in the depletion region for two diodes and they were attributed to a particular distribution of Nss located at metal-semiconductor (MS) interface. All of these results have been investigated at room temperature and results have been compared with each other. Experimental results confirmed that interfacial (Ca1.9Pr0.1Co4Ox) layer enhanced diode performance in terms of rectifier rate (RR = IF/IR at ± 3.4V), Nss (at 0.5eV) and Rsh (‑3.4V) with values of 265, 5.38 × 1013eV‑1 ṡcm‑2 and 7.87 × 104Ω for MS type Schottky barrier diode and 2.56 × 106, 1.15 × 1013eV‑1 ṡcm‑2 and 7.50 × 108Ω for metal-insulator-semiconductor (MIS) type SBD, respectively. It is clear that the rectifying ratio of MIS type SBD is about 9660 times greater than MS type SBD. The value of barrier height (BH) obtained from C-V data is higher than the forward bias I-V data and it was attributed to the nature of measurements. These results confirmed that the interfacial (Ca1.9Pr0.1Co4Ox) layer has considerably improved the performance of SD.

  11. Interfacial rheology: An overview of measuring techniques and its role in dispersions and electrospinning

    OpenAIRE

    PELIPENKO, JAN; Kristl, Julijana; Rošic, Romana; Baumgartner, Saša; Kocbek, Petra

    2012-01-01

    Interfacial rheological properties have yet to be thoroughly explored. Only recently, methods have been introduced that provide sufficient sensitivity to reliably determine viscoelastic interfacial properties. In general, interfacial rheology describes the relationship between the deformation of an interface and the stresses exerted on it. Due to the variety in deformations of the interfacial layer (shear and expansions or compressions), the field of interfacial rheology is divided into the s...

  12. Interfacial rheology: an overview of measuring techniques and its role in dispersions and electrospinning

    OpenAIRE

    Rošic, Romana; PELIPENKO, JAN; Kocbek, Petra; Baumgartner, Saša; Kristl, Julijana

    2015-01-01

    Interfacial rheological properties have yet to be thoroughly explored. Only recently, methods have been introduced that provide sufficient sensitivity to reliably determine viscoelastic interfacial properties. In general, interfacial rheology describes the relationship between the deformation of an interface and the stresses exerted on it. Due to the variety in deformations of the interfacial layer (shear and expansions or compressions), the field of interfacial rheology is divided into the s...

  13. Direct contact of indium tin oxide layer to Al(Ni) alloy electrodes for a-Si:H thin film transistors: Effects of Ni alloying on interfacial oxide growth and contact resistance

    International Nuclear Information System (INIS)

    Sputtering of indium tin oxide (ITO) on pure Al substrate produces an Al2O3 layer at the interface, leading to Schottky contact characteristics. A very small amount of Ni (2 at.% Ni) added to Al drastically reduces the contact resistance of an ITO/Al(Ni) alloy electrode to approximately 4.3 × 10-4 Ω-cm2, with a low electrical resistivity of ∼ 3 μΩ-cm, demonstrating the feasibility of using ITO/Al(Ni) alloy structures as electrodes for a-Si:H thin film transistors. The mechanism for initial interfacial oxidation occurring during sputtering of ITO on the surface of Al(Ni) and subsequent annealing at 320 °C was proposed to reveal the role of Ni during the sputtering and annealing processes. - Highlights: • Indium tin oxide (ITO)/Al(Ni) alloy contacts were fabricated. • Contact resistance of ITO/Al(Ni) alloy varied with Ni content. • Mechanism for initial interfacial oxidation during sputtering of ITO was proposed

  14. Mechanistic investigation of hydrogen-enhanced anodic dissolution of X-70 pipe steel and its implication on near-neutral pH SCC of pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Li, M.C. [Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); Institute of Materials, Shanghai University, 149 Yanchang Road, Shanghai 200072 (China); Cheng, Y.F. [Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary, Alberta T2N 1N4 (Canada)

    2007-11-01

    The effects of hydrogen-charging on anodic dissolution of pipe steel under near-neutral pH condition were studied by electrochemical techniques. Hydrogen-charging enhances the anodic dissolution rate of the steel. The hydrogen-enhanced dissolution increases with increasing charging current density. The hydrogen effect is attributed to the alteration of chemical potential and exchange current density of steel. Hydrogen-charging affects the corrosion process of the steel. In particular, at a high charging current density, a layer of corrosion product forms on the electrode surface to change corrosion potential and interfacial double-charge layer capacitance as well as charge-transfer resistance. The hydrogen effect factor for enhanced anodic dissolution of steel at an anodic potential of -0.4 V (SCE) is 1.53 only. Hydrogen-enhanced anodic dissolution of steel by itself may not be the major factor contributing to the high rate of crack growth in pipe steel in near-neutral pH electrolyte. A further investigation of the synergistic effect of hydrogen and stress on dissolution at the crack-tip is essential to determine the mechanism of near-neutral pH stress corrosion cracking of pipelines. (author)

  15. High-capacity carbon-coated titanium dioxide core-shell nanoparticles modified three dimensional anodes for improved energy output in microbial fuel cells

    Science.gov (United States)

    Tang, Jiahuan; Yuan, Yong; Liu, Ting; Zhou, Shungui

    2015-01-01

    Three-dimensional (3D) electrodes have been intensively investigated as alternatives to conventional plate electrodes in the development of high-performance microbial fuel cells (MFCs). However, the energy output of the MFCs with the 3D anodes is still limited for practical applications. In this study, a 3D anode modified with a nano-structured capacitive layer is prepared to improve the performance of an microbial fuel cell (MFC). The capacitive layer composes of titanium dioxide (TiO2) and egg white protein (EWP)-derived carbon assembled core-shell nanoparticles, which are integrated into loofah sponge carbon (LSC) to obtain a high-capacitive 3D electrode. The as-prepared 3D anode produces a power density of 2.59 ± 0.12 W m-2, which is 63% and 201% higher than that of the original LSC and graphite anodes, respectively. The increased energy output is contributed to the enhanced electrochemical capacitance of the 3D anodes as well as the synergetic effects between TiO2 and EWP-derived carbon due to their unique properties, such as relatively high surface area, good biocompatibility, and favorable surface functionalization for interfacial microbial electron transfer. The results obtained in this study will benefit the optimized design of new 3D materials to achieve enhanced performance in MFCs.

  16. Effect of post-deposition annealing on the interfacial chemical bonding states and band alignment of atomic layer deposited neodymium oxide on silicon

    International Nuclear Information System (INIS)

    The influence of post-deposition annealing on the interfacial chemical bonding states and the band offset of Nd2O3/Si is analyzed by x-ray photoelectron spectroscopy (XPS) and variable angle spectroscopic ellipsometry (VASE). By investigating the chemical shifts of the Nd 3d, O 1s and Si 2p core level spectra, it is found that the diffusion of the Si atoms from the substrates to the films occurs, and the interfacial Nd silicate-like configuration is subject to a transformation from Nd2SiO5 to Nd2Si2O7 with the annealing temperature. Moreover, the direct optical band-gap energy obtained from the VASE data shifts to a higher energy with the increasing annealing temperature and varies from 5.86 to 6.24 eV. The valence band spectra of the measured XPS gives the VBO (valance band offset) value of 1.5 eV for the as-grown annealed samples and 3.2 and 3.0 eV for the annealed samples at 700 and 900 °C, respectively. Therefore, the calculated CBO (conduction band offset) are 3.24 eV, 1.85 eV and 2.12 eV for the as-grown and annealed films at 700 °C and 900 °C. The suitable band-gap and band offsets relative to Si make Nd2O3 films one of the promising high-k dielectric candidates. (paper)

  17. Self-organized anodic TiO.sub.2./sub. nanotube layers: influence of the Ti substrate on nanotube growth and dimensions

    Czech Academy of Sciences Publication Activity Database

    Sopha, H.; Jäger, Aleš; Knotek, P.; Tesař, Karel; Jarošová, Markéta; Macák, J. M.

    2016-01-01

    Roč. 190, Feb (2016), 744-752. ISSN 0013-4686 R&D Projects: GA ČR GBP108/12/G043 Institutional support: RVO:68378271 Keywords : titanium * anodization * titanium dioxide * nanotubes * ordering Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.504, year: 2014

  18. Multilayer tape cast SOFC – Effect of anode sintering temperature

    DEFF Research Database (Denmark)

    Hauch, Anne; Birkl, Christoph; Brodersen, Karen; Jørgensen, Peter Stanley

    2012-01-01

    Multilayer tape casting (MTC) is considered a promising, cost-efficient, up-scalable shaping process for production of planar anode supported solid oxide fuel cells (SOFC). Multilayer tape casting of the three layers comprising the half cell (anode support/active anode/electrolyte) can potentially...

  19. High temperature interfacial superconductivity

    Science.gov (United States)

    Bozovic, Ivan; Logvenov, Gennady; Gozar, Adrian Mihai

    2012-06-19

    High-temperature superconductivity confined to nanometer-scale interfaces has been a long standing goal because of potential applications in electronic devices. The spontaneous formation of a superconducting interface in bilayers consisting of an insulator (La.sub.2CuO.sub.4) and a metal (La.sub.1-xSr.sub.xCuO.sub.4), neither of which is superconducting per se, is described. Depending upon the layering sequence of the bilayers, T.sub.c may be either .about.15 K or .about.30 K. This highly robust phenomenon is confined to within 2-3 nm around the interface. After exposing the bilayer to ozone, T.sub.c exceeds 50 K and this enhanced superconductivity is also shown to originate from a 1 to 2 unit cell thick interfacial layer. The results demonstrate that engineering artificial heterostructures provides a novel, unconventional way to fabricate stable, quasi two-dimensional high T.sub.c phases and to significantly enhance superconducting properties in other superconductors. The superconducting interface may be implemented, for example, in SIS tunnel junctions or a SuFET.

  20. Electrically Conductive Anodized Aluminum Surfaces

    Science.gov (United States)

    Nguyen, Trung Hung

    2006-01-01

    Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to anodized surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic, electrostaticdischarge- suppressing finishes: examples include silver impregnated anodized, black electroless nickel, black chrome, and black copper. In

  1. Experimental investigation on pulsed high-voltage cylindrical anode layer Hall plasma accelerator%高压脉冲圆柱形阳极层霍尔等离子体加速器实验

    Institute of Scientific and Technical Information of China (English)

    耿少飞; 唐德礼; 聂军伟; 高翚

    2011-01-01

    描述了一台大尺寸高压脉冲阳极层霍尔等离子体加速器。对其磁场分布进行了分析,并进行了初步实验,包括放电特征、离子流引出特征、离子束形貌等特性,以验证大尺寸的圆柱形阳极层霍尔等离子体加速器在高功率条件下的运行状况。实验发现此霍尔等离子体加速器工作稳定,可以在较高的功率上运行(大于3kW),电流利用率较高,可超出90%,工作电压范围很宽,可在300~2kV工作,束流汇聚性良好。%A pulsed high-voltage cylindrical anode layer Hall plasma accelerator is described.The magnetic field is analyzed.The preliminary experiment is performed for the performance test of large scale cylindrical anode layer Hall plasma accelerator working at high power.The results,including the I-V characteristics,anode efficiency,and the feature of the ion beam,etc,are analyzed.It is shown that this device works stably.Additionally,this plasma accelerator can be operated at high power(more than 3kW).Also it has features as such high current utilization efficiency(more than 90%),wide discharge voltage range,small ion-beam divergence.

  2. Anomalous Hall effect suppression in anatase Co:TiO2 by the insertion of an interfacial TiO2 buffer layer

    NARCIS (Netherlands)

    Lee, Y.J.; Jong, de M.P.; Wiel, van der W.G.; Kim, Y.; Brock, J.D.

    2010-01-01

    We present the effect of introducing a TiO2 buffer layer at the SrTiO3/Co:TiO2 interface on the magnetic and structural properties of anatase Co:TiO2 (1.4 at. % Co). Inserting the buffer layer leads to suppression of the room-temperature anomalous Hall effect, accompanied by a reduced density of Co

  3. Development of a multi-steps CVD process to produce bi-layers graphene for anode of Organic Light Emitting Diodes

    OpenAIRE

    Trinsoutrot, Pierre; Brignone, Mauro; Vergnes, Hugues; Caussat, Brigitte; Pullini, Daniele

    2014-01-01

    Graphene is one of the most interesting candidates for the next generation of transparent conductive electrodes (TCEs) for electrical devices, because of its unique electronic structure. Furthermore, the optical transparency of graphene films surpasses that of conventional TCEs such as indium tin oxide (ITO) [1]. However, graphene anode for Organic Light Emitting Diodes (OLEDs) still presents several problems owing to its low work function and high sheet resistance [1], which may be related t...

  4. Thin layers elaborated from new anodic and cathodic materials for lithium-ions micro-batteries; Nouveaux materiaux d'electrodes elabores sous forme de couches minces pour batteries lithium-ion

    Energy Technology Data Exchange (ETDEWEB)

    Benjelloun, N.

    2002-12-01

    Thin layers elaborated by R.F. sputtering from new anodic and cathodic materials were investigated as electrodes for lithium-ion micro-batteries. Anodic thin films based on the Tin Composite Oxides (TCOs) were found to exhibit interesting electrochemical characteristics. However, the irreversible capacity loss occurring during the first charge and due to the reduction of tin oxide remains a drawback. According to the gold collector contribution to the faradic yield, electrochemical behavior of metallic thin films (Au, Ag, Cu, Zn, etc...) was studied. AuCuAg and Ag based thin films were associated via an aprotic or solid electrolyte (LiPON) to Li{sub 1+x}Mn{sub 1,5}Ni{sub 0,5}O{sub 4} thin layers in order to build up mini or micro batteries with an average voltage close to 4,7 V. However, all solid state micro-batteries were found to present high ohmic drop. (author)

  5. Improving charge transport of P3HT:PCBM organic solar cell using MoO3 nanoparticles as an interfacial buffer layer

    Science.gov (United States)

    Kim, Jae-Hyoung; Park, Eung-Kyu; Kim, Ji-Hwan; Cho, Hyeong Jun; Lee, Dong-Hoon; Kim, Yong-Sang

    2016-05-01

    In this work, P3HT:PCBM based organic solar cells (OSCs) were fabricated. We investigated the protection of PEDOT:PSS from active layer using the solution processed molybdenum oxide nanoparticles layer (MoO3 NPs, ≤100 nm). The device structure was ITO/ZnO/P3HT: PCBM/MoO3/PEDOT:PSS/Ag. A thin film MoO3 NPs was spin-coated and it acts as a hole transporting layer between the active layer and PEDOT:PSS. The MoO3 NPs based device showed an improved short circuit current compared without MoO3 NP layer. The pristine OSCs showed short circuit current density ( J sc ) of 11.56 mA/cm2 and PCE of 3.70% under AM 1.5G (100 mW/cm2). MoO3 NPs based device showed an increased PCE of 4.11% with J sc of 12.74 mA/cm2. MoO3 NPs also decreased the charge recombination and resistance of the OSCs. [Figure not available: see fulltext.

  6. Analysis on the interfacial properties of transparent conducting oxide and hydrogenated p-type amorphous silicon carbide layers in p–i–n amorphous silicon thin film solar cell structure

    International Nuclear Information System (INIS)

    Quantitative estimation of the specific contact resistivity and energy barrier at the interface between transparent conducting oxide (TCO) and hydrogenated p-type amorphous silicon carbide (a-Si1−xCx:H(p)) was carried out by inserting an interfacial buffer layer of hydrogenated p-type microcrystalline silicon (μc-Si:H(p)) or hydrogenated p-type amorphous silicon (a-Si:H(p)). In addition, superstrate configuration p–i–n hydrogenated amorphous silicon (a-Si:H) solar cells were fabricated by plasma enhanced chemical vapor deposition to investigate the effect of the inserted buffer layer on the solar cell device. Ultraviolet photoelectron spectroscopy was employed to measure the work functions of the TCO and a-Si1−xCx:H(p) layers and to allow direct calculations of the energy barriers at the interfaces. Especially interface structures were compared with/without a buffer which is either highly doped μc-Si:H(p) layer or low doped a-Si:H(p) layer, to improve the contact properties of aluminum-doped zinc oxide and a-Si1−xCx:H(p). Out of the two buffers, the superior contact properties of μc-Si:H(p) buffer could be expected due to its higher conductivity and slightly lower specific contact resistivity. However, the overall solar cell conversion efficiencies were almost the same for both of the buffered structures and the resultant similar efficiencies were attributed to the difference between the fill factors of the solar cells. The effects of the energy barrier heights of the two buffered structures and their influence on solar cell device performances were intensively investigated and discussed with comparisons. - Highlights: ► Decrease of fill factor due to high contact resistance of Al:ZnO/a-SiC:H(p) interface. ► Insertion of buffer layer (μc-Si or a-Si) between Al:ZnO and p-layer for comparison. ► μc-Si:H(p) buffer with high conductivity has better fill factor but higher barrier. ► a-Si:H(p) buffer with low conductivity forms lower barrier and

  7. Vacuum arc anode phenomena

    International Nuclear Information System (INIS)

    A brief review of anode phenomena in vacuum arcs is presented. Discussed in succession are: the transition of the arc into the anode spot mode; the temperature of the anode before, during and after the anode spot forms; and anode ions. Characteristically the anode spot has a temperature of the order of the atmospheric boiling point of the anode material and is a copious source of vapor and energetic ions. The dominant mechanism controlling the transition of the vacuum arc into the anode spot mode appears to depend upon the electrode geometry, the electrode material, and the current waveform of the particular vacuum arc being considered. Either magnetic constriction in the gap plasma or gross anode melting can trigger the transition; indeed, a combination of the two is a common cause of anode spot formation

  8. The influence of MoOx gap states on hole injection from aluminum doped zinc oxide with nanoscale MoOx surface layer anodes for organic light emitting diodes

    International Nuclear Information System (INIS)

    The effective workfunction of Al doped ZnO films (AZO) increased from 4.1 eV to 5.55 eV after surface modification with nanoscale molybdenum sub-oxides (MoOx). Hole only devices with anodes consisting of 3 nm of MoOx on AZO exhibited a lower turn-on voltage (1.5 vs 1.8 V), and larger charge injection (190 vs 118 mA/cm2) at the reference voltage, compared to indium tin oxide (ITO). AZO devices with 10 nm of MoOx exhibited the highest workfunction but performed poorly compared to devices with 3 nm of MoOx, or standard ITO. Ultraviolet photoelectron, X-ray photoelectron, and optical spectroscopies indicate that the 3 nm MoOx films are more reduced and farther away from MoO3 stoichiometry than their 10 nm equivalents. The vacancies associated with non-stoichiometry result in donor-like gap states which we assign to partially occupied Mo 4d levels. We propose that Fowler-Nordheim tunneling from these levels is responsible for the reduction in threshold voltage measured in devices with 3 nm of MoOx. A schematic band diagram is proposed. The thicker MoOx layers are more stoichiometric and resistive, and the voltage drop across these layers dominates their electrical performance, leading to an increase in threshold voltage. The results indicate that AZO with MoOx layers of optimal thickness may be potential candidates for anode use in organic light emitting diodes

  9. The influence of MoO{sub x} gap states on hole injection from aluminum doped zinc oxide with nanoscale MoO{sub x} surface layer anodes for organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Jha, Jitendra Kumar; Santos-Ortiz, Reinaldo; Du, Jincheng; Shepherd, Nigel D., E-mail: Nigel.shepherd@unt.edu [Department of Materials Science and Engineering, University of North Texas, Denton, Texas 76203-5017 (United States)

    2015-08-14

    The effective workfunction of Al doped ZnO films (AZO) increased from 4.1 eV to 5.55 eV after surface modification with nanoscale molybdenum sub-oxides (MoO{sub x}). Hole only devices with anodes consisting of 3 nm of MoO{sub x} on AZO exhibited a lower turn-on voltage (1.5 vs 1.8 V), and larger charge injection (190 vs 118 mA/cm{sup 2}) at the reference voltage, compared to indium tin oxide (ITO). AZO devices with 10 nm of MoO{sub x} exhibited the highest workfunction but performed poorly compared to devices with 3 nm of MoO{sub x}, or standard ITO. Ultraviolet photoelectron, X-ray photoelectron, and optical spectroscopies indicate that the 3 nm MoO{sub x} films are more reduced and farther away from MoO{sub 3} stoichiometry than their 10 nm equivalents. The vacancies associated with non-stoichiometry result in donor-like gap states which we assign to partially occupied Mo 4d levels. We propose that Fowler-Nordheim tunneling from these levels is responsible for the reduction in threshold voltage measured in devices with 3 nm of MoO{sub x}. A schematic band diagram is proposed. The thicker MoO{sub x} layers are more stoichiometric and resistive, and the voltage drop across these layers dominates their electrical performance, leading to an increase in threshold voltage. The results indicate that AZO with MoO{sub x} layers of optimal thickness may be potential candidates for anode use in organic light emitting diodes.

  10. Fabrication of anodic aluminum oxide with incorporated chromate ions

    Science.gov (United States)

    Stępniowski, Wojciech J.; Norek, Małgorzata; Michalska-Domańska, Marta; Bombalska, Aneta; Nowak-Stępniowska, Agata; Kwaśny, Mirosław; Bojar, Zbigniew

    2012-10-01

    The anodization of aluminum in 0.3 M chromic acid is studied. The influence of operating conditions (like anodizing voltage and electrolyte's temperature) on the nanoporous anodic aluminum oxide geometry (including pore diameter, interpore distance, the oxide layer thickness and pores density) is thoroughly investigated. The results revealed typical correlations of the anodic alumina nanopore geometry with operating conditions, such as linear increase of pore diameter and interpore distance with anodizing voltage. The anodic aluminum oxide is characterized by a low pores arrangement, as determined by Fast Fourier transforms analyses of the FE-SEM images, which translates into a high concentration of oxygen vacancies. Moreover, an optimal experimental condition where chromate ions are being successfully incorporated into the anodic alumina walls, have been determined: the higher oxide growth rate the more chromate ions are being trapped. The trapped chromate ions and a high concentration of oxygen vacancies make the anodic aluminum oxide a promising luminescent material.

  11. Phase diagrams modified by interfacial penalties

    Directory of Open Access Journals (Sweden)

    Atanacković T.M.

    2007-01-01

    Full Text Available The conventional forms of phase diagrams are constructed without consideration of interfacial energies and they represent an impor­tant tool for chemical engineers and metallurgists. If interfacial energies are taken into consideration, it is intuitively obvious that the regions of phase equilibria must become smaller, because there is a penalty on the formation of interfaces. We investigate this phe­nomenon qualitatively for a one-dimensional model, in which the phases occur as layers rather than droplets or bubbles. The modified phase diagrams are shown in Chapters 3 and 4.

  12. Surface and interfacial reaction study of half cycle atomic layer deposited HfO2 on chemically treated GaSb surfaces

    International Nuclear Information System (INIS)

    An in situ half-cycle atomic layer deposition/X-ray photoelectron spectroscopy (XPS) study was conducted in order to investigate the evolution of the HfO2 dielectric interface with GaSb(100) surfaces after sulfur passivation and HCl etching, designed to remove the native oxides. With the first pulses of tetrakis(dimethylamido)hafnium(IV) and water, a decrease in the concentration of antimony oxide states present on the HCl-etched surface is observed, while antimony sulfur states diminished below the XPS detection limit on sulfur passivated surface. An increase in the amount of gallium oxide/sulfide is seen, suggesting oxygen or sulfur transfers from antimony to gallium during antimony oxides/sulfides decomposition.

  13. Influence of enzymatic reactions on the electrochemical behavior of EN X2CrNiMo17-11-2 (AISI 316L) stainless steel in bio-corrosion: role of interfacial processes on the modification of the passive layer

    International Nuclear Information System (INIS)

    The outstanding corrosion behavior of stainless steels (SS) results from the presence of thin oxide layer (some nanometers). In non sterile aqueous media, stainless steels may exhibit a non stable behavior resulting from interactions between microbial species and passive film. In fact, microorganisms can be deeply involved in the corrosion processes usually reported as Microbial Influenced Corrosion (MIC). They can induce the initiation or the acceleration of this phenomenon and they do so when organized in bio-films. From the electrochemical point of view, stainless steels showed an increase of the free corrosion potential (Ecorr) attributed to the bio-film settlement. The Eco' ennoblement was broadly reported in seawater and seems to be confirmed in fresh water according to recent findings. A considerable progress in the comprehension of MIC processes was related to the role of extracellular species, essentially enzymes. Many enzymatic reactions occurring in bio-films consist on using oxygen as electron acceptor to generate hydrogen peroxide and related species. The aim of this work is to understand the mechanisms involved in the electrochemical behavior of stainless steel according to an enzymatic approach in medium simulating fresh water. To this end, glucose oxidase was chosen to globalize aerobic activities of bio-films. Electrochemical measurements in situ and surface analysis allow the comprehension of the role and the nature of interfacial processes. Surface characterization was performed with the help of a new quantitative utilization of XPS analysis and AFM. Results show a significant evolution in term of morphology (surface organization), (ii) chemical composition (passive layer, adsorbed organic species) and (iii) chemical reaction (oxidation, dissolution, effect of enzyme). Finally, a new enzymatic system is proposed to mimic specific physicochemical conditions at the SS / bio-film interface, in particular enzymatic generation of oxidant species in

  14. Lithium Ion Battery Anode Aging Mechanisms

    Directory of Open Access Journals (Sweden)

    Victor Agubra

    2013-03-01

    Full Text Available Degradation mechanisms such as lithium plating, growth of the passivated surface film layer on the electrodes and loss of both recyclable lithium ions and electrode material adversely affect the longevity of the lithium ion battery. The anode electrode is very vulnerable to these degradation mechanisms. In this paper, the most common aging mechanisms occurring at the anode during the operation of the lithium battery, as well as some approaches for minimizing the degradation are reviewed.

  15. Interfacial mechanics of graphene

    OpenAIRE

    Zhu, Yong

    2014-01-01

    Interfacial mechanics between graphene and substrate such as friction and adhesion plays a critical role in the morphology and functionality of graphene-based devices. Here I will present the interface sliding and buckling of monolayer graphene on a stretchable substrate. The nonlinear mechanical response of monolayer graphene on polyethylene terephthalate (PET) is characterized using in-situ Raman spectroscopy and atomic force microscopy. Although interfacial stress transfer leads to tension...

  16. crossover of interfacial dynamics

    OpenAIRE

    Jasnow, D.; Zia, R. K. P.

    1987-01-01

    Some dynamical models in which there is a significant interplay between interfacial and bulk degrees of freedom are treated at the mean-field (or Van Hove) level from a coarse-grained microscopic viewpoint. Specifically, the near-equilibrium interfacial dynamics of two of the simplest models with conservation laws, models B and C, are studied with use of (as appropriate) variational techniques, perturbation theory, and (with certain additional simplifications) exact solutions. Use of these me...

  17. Model of interfacial melting

    DEFF Research Database (Denmark)

    Mouritsen, Ole G.; Zuckermann, Martin J.

    1987-01-01

    A two-dimensional model is proposed to describe systems with phase transitions which take place in terms of crystalline as well as internal degrees of freedom. Computer simulation of the model shows that the interplay between the two sets of degrees of freedom permits observation of grain-boundar......-boundary formation and interfacial melting, a nonequilibrium process by which the system melts at the boundaries of a polycrystalline domain structure. Lipid membranes are candidates for systems with pronounced interfacial melting behavior....

  18. Impedance spectroscopy of highly ordered nano-porous electrodes based on Au-AAO (anodic aluminum oxide) structure.

    Science.gov (United States)

    Ahn, Jaehwan; Cho, Sungbo; Min, Junhong

    2013-11-01

    Electrochemical measurements using the microelectrodes are increasingly utilized for the label-free detection of the small amount of biological materials such as DNA, protein, and cells. However, the interfacial electrode impedance increases and may hinder the detection of weak signals as the size of electrode decreases. To enhance the measurement sensitivity while reducing the electrode size, in this study, microelectrodes employing a nanoporous structure were fabricated and characterized by using electrical impedance spectroscopy. We made the highly ordered honeycomb nanoporous structure of Anodic Aluminum Oxide (AAO) by electrochemical anodizing and formed Au layer on the surface of AAO (Au/AAO) by electroless Au plating method. The electrical characteristics of the fabricated Au/AAO electrodes were evaluated by using de Levie's model derived for the pore electrodes. As a result, the interfacial electrode impedance of the fabricated Au/AAO electrodes was 2-3 order lower than the value of the planar electrodes at frequencies below 1 kHz. It implies this nanoporous electrode could be directly applied to label free detection of biomaterials. PMID:24245278

  19. Ellipsometry of anodic film growth

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.G.

    1978-08-01

    An automated computer interpretation of ellisometer measurements of anodic film growth was developed. Continuous mass and charge balances were used to utilize more fully the time dependence of the ellipsometer data and the current and potential measurements. A multiple-film model was used to characterize the growth of films which proceeds via a dissolution--precipitation mechanism; the model also applies to film growth by adsorption and nucleation mechanisms. The characteristic parameters for film growth describe homogeneous and heterogeneous crystallization rates, film porosities and degree of hydration, and the supersaturation of ionic species in the electrolyte. Additional descriptions which may be chosen are patchwise film formation, nonstoichiometry of the anodic film, and statistical variations in the size and orientation of secondary crystals. Theories were developed to describe the optical effects of these processes. An automatic, self-compensating ellipsometer was used to study the growth in alkaline solution of anodic films on silver, cadmium, and zinc. Mass-transport conditions included stagnant electrolyte and forced convection in a flow channel. Multiple films were needed to characterize the optical properties of these films. Anodic films grew from an electrolyte supersatuated in the solution-phase dissolution product. The degree of supersaturation depended on transport conditions and had a major effect on the structure of the film. Anodic reaction rates were limited by the transport of charge carriers through a primary surface layer. The primary layers on silver, zinc, and cadmium all appeared to be nonstoichiometric, containing excess metal. Diffusion coefficients, transference numbers, and the free energy of adsorption of zinc oxide were derived from ellipsometer measurements. 97 figures, 13 tables, 198 references.

  20. Advances in aluminum anodizing

    Science.gov (United States)

    Dale, K. H.

    1969-01-01

    White anodize is applied to aluminum alloy surfaces by specific surface preparation, anodizing, pigmentation, and sealing techniques. The development techniques resulted in alloys, which are used in space vehicles, with good reflectance values and excellent corrosive resistance.

  1. Mussel-Inspired Polydopamine Coating for Enhanced Thermal Stability and Rate Performance of Graphite Anodes in Li-Ion Batteries.

    Science.gov (United States)

    Park, Seong-Hyo; Kim, Hyeon Jin; Lee, Junmin; Jeong, You Kyeong; Choi, Jang Wook; Lee, Hochun

    2016-06-01

    Despite two decades of commercial history, it remains very difficult to simultaneously achieve both high rate capability and thermal stability in the graphite anodes of Li-ion batteries because the stable solid electrolyte interphase (SEI) layer, which is essential for thermal stability, impedes facile Li(+) ion transport at the interface. Here, we resolve this longstanding challenge using a mussel-inspired polydopamine (PD) coating via a simple immersion process. The nanometer-thick PD coating layer allows the formation of an SEI layer on the coating surface without perturbing the intrinsic properties of the SEI layer of the graphite anodes. PD-coated graphite exhibits far better performances in cycling test at 60 °C and storage test at 90 °C than bare graphite. The PD-coated graphite also displays superior rate capability during both lithiation and delithiation. As evidenced by surface free energy analysis, the enhanced performance of the PD-coated graphite can be ascribed to the Lewis basicity of the PD, which scavenges harmful hydrofluoric acid and forms an intermediate triple-body complex among a Li(+) ion, solvent molecules, and the PD's basic site. The usefulness of the proposed PD coating can be expanded to various electrodes in rechargeable batteries that suffer from poor thermal stability and interfacial kinetics. PMID:27183170

  2. L{sub g} = 100 nm In{sub 0.7}Ga{sub 0.3}As quantum well metal-oxide semiconductor field-effect transistors with atomic layer deposited beryllium oxide as interfacial layer

    Energy Technology Data Exchange (ETDEWEB)

    Koh, D., E-mail: dh.koh@utexas.edu, E-mail: Taewoo.Kim@sematech.org [Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States); SEMATECH, Inc., Albany, New York 12203 (United States); Kwon, H. M. [Department of Electronics Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Kim, T.-W., E-mail: dh.koh@utexas.edu, E-mail: Taewoo.Kim@sematech.org; Veksler, D.; Gilmer, D.; Kirsch, P. D. [SEMATECH, Inc., Albany, New York 12203 (United States); Kim, D.-H. [SEMATECH, Inc., Albany, New York 12203 (United States); GLOBALFOUNDRIES, Malta, New York 12020 (United States); Hudnall, Todd W. [Department of Chemistry and Biochemistry, Texas State University, San Marcos, Texas, 78666 (United States); Bielawski, Christopher W. [Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712 (United States); Maszara, W. [GLOBALFOUNDRIES, Santa Clara, California 95054 (United States); Banerjee, S. K. [Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States)

    2014-04-21

    In this study, we have fabricated nanometer-scale channel length quantum-well (QW) metal-oxide-semiconductor field effect transistors (MOSFETs) incorporating beryllium oxide (BeO) as an interfacial layer. BeO has high thermal stability, excellent electrical insulating characteristics, and a large band-gap, which make it an attractive candidate for use as a gate dielectric in making MOSFETs. BeO can also act as a good diffusion barrier to oxygen owing to its small atomic bonding length. In this work, we have fabricated In{sub 0.53}Ga{sub 0.47}As MOS capacitors with BeO and Al{sub 2}O{sub 3} and compared their electrical characteristics. As interface passivation layer, BeO/HfO{sub 2} bilayer gate stack presented effective oxide thickness less 1 nm. Furthermore, we have demonstrated In{sub 0.7}Ga{sub 0.3}As QW MOSFETs with a BeO/HfO{sub 2} dielectric, showing a sub-threshold slope of 100 mV/dec, and a transconductance (g{sub m,max}) of 1.1 mS/μm, while displaying low values of gate leakage current. These results highlight the potential of atomic layer deposited BeO for use as a gate dielectric or interface passivation layer for III–V MOSFETs at the 7 nm technology node and/or beyond.

  3. Interfacial study and energy-band alignment of annealed Al2O3 films prepared by atomic layer deposition on 4H-SiC

    International Nuclear Information System (INIS)

    Al2O3 films were prepared by atomic layer deposition using trimethylaluminum and H2O at 250 °C on 4H-SiC substrates and annealed at 1000 °C in N2. The as-deposited and annealed Al2O3 films were measured and analyzed near the Al2O3/SiC interfaces by using an X-ray photoelectron spectroscopy (XPS) with etching processing. The XPS results showed that as-deposited Al2O3 films were O-rich and converted to anhydride Al2O3 films after annealed at 1000 °C in N2. Si suboxides were found both at as-deposited and annealed Al2O3/SiC interfaces. Energy band shift between Al2O3 and 4H-SiC was found after annealing. The conduction band offsets of as-grown and annealed Al2O3/SiC were 1.90 and 1.53 eV, respectively. These results demonstrated that Al2O3 can be a good candidate to be applied in SiC metal-oxide-semiconductor devices.

  4. Impact of post-deposition annealing on interfacial chemical bonding states between AlGaN and ZrO{sub 2} grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Gang; Arulkumaran, Subramaniam; Ng, Geok Ing; Li, Yang; Ang, Kian Siong [Novitas, Nanoelectronics Center of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Wang, Hong, E-mail: ewanghong@ntu.edu.sg [Novitas, Nanoelectronics Center of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); CINTRA CNRS/NTU/Thales, UMI 3288, 50 Nanyang Drive (Singapore); Ng, Serene Lay Geok; Ji, Rong [Data Storage Institute, Agency for Science Technology and Research (A-STAR), 5 Engineering Drive 1, 117608 (Singapore); Liu, Zhi Hong [Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, Singapore 138602 (Singapore)

    2015-03-02

    The effect of post-deposition annealing on chemical bonding states at interface between Al{sub 0.5}Ga{sub 0.5}N and ZrO{sub 2} grown by atomic layer deposition (ALD) is studied by angle-resolved x-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. It has been found that both of Al-O/Al 2p and Ga-O/Ga 3d area ratio decrease at annealing temperatures lower than 500 °C, which could be attributed to “clean up” effect of ALD-ZrO{sub 2} on AlGaN. Compared to Ga spectra, a much larger decrease in Al-O/Al 2p ratio at a smaller take-off angle θ is observed, which indicates higher effectiveness of the passivation of Al-O bond than Ga-O bond through “clean up” effect near the interface. However, degradation of ZrO{sub 2}/AlGaN interface quality due to re-oxidation at higher annealing temperature (>500 °C) is also found. The XPS spectra clearly reveal that Al atoms at ZrO{sub 2}/AlGaN interface are easier to get oxidized as compared with Ga atoms.

  5. Interfacial charge-induced polarization switching in Al{sub 2}O{sub 3}/Pb(Zr,Ti)O{sub 3} bi-layer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yu Jin; Park, Min Hyuk; Jeon, Woojin; Kim, Han Joon; Moon, Taehwan; Lee, Young Hwan; Kim, Keum Do; Hyun, Seung Dam; Hwang, Cheol Seong, E-mail: cheolsh@snu.ac.kr [Department of Materials Science & Engineering and Inter-University Semiconductor Research Center, College of Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)

    2015-12-14

    Detailed polarization switching behavior of an Al{sub 2}O{sub 3}/Pb(Zr,Ti)O{sub 3} (AO/PZT) structure is examined by comparing the phenomenological thermodynamic model to the experimental polarization–voltage (P-V) results. Amorphous AO films with various thicknesses (2–10 nm) were deposited on the polycrystalline 150-nm-thick PZT film. The thermodynamic calculation showed that the transition from the ferroelectric-like state to the paraelectric-like state with increasing AO thickness occurs at ∼3 nm thickness. This paraelectric-like state should have exhibited a negative capacitance effect without permanent polarization switching if no other adverse effects are involved. However, experiments showed typical ferroelectric-like hysteresis loops where the coercive voltage increased with the increasing AO thickness, which could be explained by the carrier injection through the thin AO layer and trapping of the carriers at the AO/PZT interface. The fitting of the experimental P-V loops using the thermodynamic model considering the depolarization energy effect showed that trapped charge density was ∼±0.1 Cm{sup −2} and critical electric field at the Pt electrode/AO interface, at which the carrier transport occurs, was ∼±10 MV/cm irrespective of the AO thickness. Energy band model at each electrostatic state along the P-V loop was provided to elucidate correlation between macroscopic polarization and internal charge state of the stacked films.

  6. Energy Parameters of Interfacial Layers in Composite Systems: Graphene – (Si, Cu, Fe, Co, Au, Ag, Al, Ru, Hf, Pb and Semiconductor (Si,Ge – (Fe, Co, Cu, Al, Au, Cr, W, Pb

    Directory of Open Access Journals (Sweden)

    B.P. Koman

    2015-12-01

    Full Text Available On the basis of the non-equilibrium thermodynamics relations and the surface physics phenomena we calculate adhesion and energy parameters to characterize the interfacial interactions in graphene – (Si, Cu, Fe, Co, Au, Ag, Al, Ru, Hf, Pb and semiconductor (Si, Ge – (Fe, Co, Cu, Al, Au, Cr, W, Pb systems. We analyze trends of the interfacial energy, interfacial tension, work of adhesion and the energy of adhesive bonds on the contacting element’s atomic number in the periodic table and on the electronegativity difference of interacting elements. Thus, this work provides theoretical basis for the development of new composite materials.

  7. Modeling of an anode-supported Ni-YSZ vertical stroke Ni-ScSZ vertical stroke ScSZ vertical stroke LSM-ScSZ multiple layers SOFC cell. Part II. Simulations and discussion

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Yixiang; Cai, Ningsheng; Li, Chen; Bao, Cheng [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Tsinghua University, Beijing 100084 (China); Croiset, Eric [Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Qian, Jiqin; Hu, Qiang; Wang, Shaorong [Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS), 1295 Dingxi Road, Shanghai 200050 (China)

    2007-10-11

    In part I of the present study, a two-dimensional isothermal mechanistic model of a composite yttria/scandia stabilized zirconia anode-supported multiple layers solid oxide fuel cell (Ni-YSZ vertical stroke Ni-ScSZ vertical stroke ScSZ vertical stroke LSM-ScSZ) was developed, calibrated and validated using a button cell setup. In this paper, the model was further validated for extended operating conditions of fuel and oxidant compositions, which confirmed the robustness of the model. Since an important attribute of this model is its ability to accurately describe the effect of cell microstructure on cell performance, a large section of part II is devoted to sensitivity analysis of various microstructure parameters (cathode area, porosity, layer thickness and particle radius) on cell performance. In particular, the simulation results have shown how the button cell microstructure should be modified to optimize its performance. The proposed model could be used as a bridge between micro-scale electrode models and macro-scale unit cell simulation, thus being a useful tool for electrode design. (author)

  8. Interfacial engineering of microstructured materials

    Science.gov (United States)

    Poda, Aimee

    The tribological behavior of octadecyltrichlorosilane self assembled monolayers (OTS-SAMs) has been successfully exploited to reduce energy losses and to produce adequate adhesion barrier properties on many MEMS surfaces. Unfortunately, performance discrepancies are reported in the literature between films produced on smooth surfaces as compared to typical MEMS surfaces maintaining topographical roughness. Rational explanations in terms of reproducibility issues, production considerations, and the scale of measurement technique have been introduced to account for some of the variation. The tribological phenomena at the micro-scale are complicated by the fact that rather than inertial effects, the forces associated with the surface become dominant factors influencing the mechanical behavior of contacting components. In MEMS, real mechanical contacts typically consist of a few nanometer scale asperities. Furthermore, various surface topographies exist for MEMS device fabrication and their corresponding asperity profiles can vary drastically based on the production process. This dissertation presents research focusing on the influence of topographical asperities on OTS film properties of relevance for efficient tribological improvement. A fundamental approach has been taken to carefully examine the factors that contribute to high quality film formation, specifically formation temperature and the role of interfacial water layer associated with the sample surface. As evidenced on smooth surfaces, the characteristics for successful tribological performance of OTS films are strongly dependent on the lateral packing density and molecular orientation of the monolayer. Limited information is available on how monolayers associate on topographical asperities and whether these topographical asperities influence the interfacial reactivity of MEMS surfaces. A silica film produced from a low temperature, vapor-phase hydrolysis of tetrachlorosilane with a tunable topography is

  9. Rheology of interfacial protein-polysaccharide composites

    Science.gov (United States)

    Fischer, P.

    2013-05-01

    The morphology and mechanical properties of protein adsorption layers can significantly be altered by the presence of surfactants, lipids, particles, other proteins, and polysaccharides. In food emulsions, polysaccharides are primarily considered as bulk thickener but can under appropriate environmental conditions stabilize or destabilize the protein adsorption layer and, thus, the entire emulsion system. Despite their ubiquitous usage as stabilization agent, relatively few investigations focus on the interfacial rheology of composite protein/polysaccharide adsorption layers. The manuscript provides a brief review on both main stabilization mechanisms, thermodynamic phase separation and electrostatic interaction and discusses the rheological response in light of the environmental conditions such as ionic strength and pH.

  10. A Peanut Shell Inspired Scalable Synthesis of Three-Dimensional Carbon Coated Porous Silicon Particles as an Anode for Lithium-Ion Batteries

    International Nuclear Information System (INIS)

    Highlights: • A novel, economical ball milling and heat treatment of porous silicon based anodes was introduced to boost the electrochemical performance of Li-ion batteries. • The compact C/SiO2-coated peanut shell-like electrodes could accommodate volume change effectively. • The electrodes exhibited outstanding cycling performance and rate capacities. • Our work gives a compelling look at a novel and large-scale production method of fabricating next generation Si/C anodes for high-performance LIBs. - Abstract: A novel, economical ball milling and heat treatment of porous silicon based anodes was introduced to boost the electrochemical performance and cycle capacity of Li-ion batteries. The resultant peanut shell-like electrodes combined multiple advantageous features, including a continuous, flexible electrically conductive carbon network, a synergistic C/SiO2 coating layer and improved interfacial contact, in a peanut shell structure with void space. The electrodes achieved an initial discharge capacity of 1909 mA h g−1 with coulombic efficiency of 88.8% as well as a high reversible capacity of 1179 mA h g−1 after 120 cycles at 0.1C. In addition, the material was capable of reaching a capacity of 493 mA h g−1 even at the high charge rate of 4C. This work gives a compelling look at a novel and large-scale production method of fabricating next generation Si/C anodes for high-performance LIBs

  11. Battery, especially for portable devices, has an anode containing silicon

    OpenAIRE

    S. Y. Kan

    2002-01-01

    The anode (2) contains silicon. A battery with a silicon-containing anode is claimed. An Independent claim is also included for a method used to make the battery, comprising the doping of a silicon substrate (1) with charge capacity-increasing material (preferably boron, phosphorous or arsenic), etching the doped substrate layer in order to increase its porosity, and applying a cathode (3) in the form of a lithium oxide compound onto the resulting anode and applying an electrolyte (4) to the ...

  12. Emulsions for interfacial filtration.

    Energy Technology Data Exchange (ETDEWEB)

    Grillet, Anne Mary; Bourdon, Christopher Jay; Souza, Caroline Ann; Welk, Margaret Ellen; Hartenberger, Joel David; Brooks, Carlton, F.

    2006-11-01

    We have investigated a novel emulsion interfacial filter that is applicable for a wide range of materials, from nano-particles to cells and bacteria. This technology uses the interface between the two immiscible phases as the active surface area for adsorption of targeted materials. We showed that emulsion interfaces can effectively collect and trap materials from aqueous solution. We tested two aqueous systems, a bovine serum albumin (BSA) solution and coal bed methane produced water (CBMPW). Using a pendant drop technique to monitor the interfacial tension, we demonstrated that materials in both samples were adsorbed to the liquid-liquid interface, and did not readily desorb. A prototype system was built to test the emulsion interfacial filter concept. For the BSA system, a protein assay showed a progressive decrease in the residual BSA concentration as the sample was processed. Based on the initial prototype operation, we propose an improved system design.

  13. Porous and mesh alumina formed by anodization of high purity aluminum films at low anodizing voltage

    International Nuclear Information System (INIS)

    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

  14. 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.

  15. Pre-treatments applied to oxidized aluminum surfaces to modify the interfacial bonding with bis-1,2-(triethoxysilyl)ethane (BTSE)

    International Nuclear Information System (INIS)

    The methods of X-ray photoelectron spectroscopy (XPS), secondary-ion mass spectrometry (SIMS), and scanning electron microscopy (SEM) have been used to investigate aspects of the bonding of bis-1,2-(triethoxysilyl)ethane (BTSE) onto anodized samples of 7075-T6 aluminum alloy that have been subjected to the various pre-treatments considered in Part I. The oxide layer thins when this sample is subjected to a Forest Products Laboratory (FPL) treatment; topographical changes are detected by SEM after only 5 min, and the 'scallop structures' increase in size for longer times of the FPL treatment. These 7075-Al surfaces adsorb more BTSE than the high-purity Al samples considered in Part I, although the interfacial bonding indicated by the [AlOSi]+/[Al2O]+ SIMS ratios measured for the former samples are constant for different times of FPL treatment, unlike the situation for high-purity Al. Heating anodized 7075-Al samples, either before or after FPL treatment, has no significant effect on the subsequent BTSE adsorption, but a H2 plasma treatment can enhance the interfacial Al-O-Si bonding with a decrease in the total BTSE polymerization

  16. Organic electrophosphorescence device having interfacial layers

    Science.gov (United States)

    Choulis, Stelios A.; Mathai, Mathew; Choong, Vi-En; So, Franky

    2010-08-10

    Techniques are described for forming an organic light emitting diode device with improved device efficiency. Materials having at least one energy level that is similar to those of a phosphorescent light emitting material in the diode are incorporated into the device to directly inject holes or electrons to the light emitting material.

  17. Probing Interfacial Water on Nanodiamonds in Colloidal Dispersion.

    Science.gov (United States)

    Petit, Tristan; Yuzawa, Hayato; Nagasaka, Masanari; Yamanoi, Ryoko; Osawa, Eiji; Kosugi, Nobuhiro; Aziz, Emad F

    2015-08-01

    The structure of interfacial water layers around nanoparticles dispersed in an aqueous environment may have a significant impact on their reactivity and on their interaction with biological species. Using transmission soft X-ray absorption spectroscopy in liquid, we demonstrate that the unoccupied electronic states of oxygen atoms from water molecules in aqueous colloidal dispersions of nanodiamonds have a different signature than bulk water. X-ray absorption spectroscopy can thus probe interfacial water molecules in colloidal dispersions. The impacts of nanodiamond surface chemistry and concentration on interfacial water electronic signature are discussed. PMID:26267179

  18. Interconnected hollow carbon nanospheres for stable lithium metal anodes.

    Science.gov (United States)

    Zheng, Guangyuan; Lee, Seok Woo; Liang, Zheng; Lee, Hyun-Wook; Yan, Kai; Yao, Hongbin; Wang, Haotian; Li, Weiyang; Chu, Steven; Cui, Yi

    2014-08-01

    For future applications in portable electronics, electric vehicles and grid storage, batteries with higher energy storage density than existing lithium ion batteries need to be developed. Recent efforts in this direction have focused on high-capacity electrode materials such as lithium metal, silicon and tin as anodes, and sulphur and oxygen as cathodes. Lithium metal would be the optimal choice as an anode material, because it has the highest specific capacity (3,860 mAh g(-1)) and the lowest anode potential of all. However, the lithium anode forms dendritic and mossy metal deposits, leading to serious safety concerns and low Coulombic efficiency during charge/discharge cycles. Although advanced characterization techniques have helped shed light on the lithium growth process, effective strategies to improve lithium metal anode cycling remain elusive. Here, we show that coating the lithium metal anode with a monolayer of interconnected amorphous hollow carbon nanospheres helps isolate the lithium metal depositions and facilitates the formation of a stable solid electrolyte interphase. We show that lithium dendrites do not form up to a practical current density of 1 mA cm(-2). The Coulombic efficiency improves to ∼ 99% for more than 150 cycles. This is significantly better than the bare unmodified samples, which usually show rapid Coulombic efficiency decay in fewer than 100 cycles. Our results indicate that nanoscale interfacial engineering could be a promising strategy to tackle the intrinsic problems of lithium metal anodes. PMID:25064396

  19. Interfacial phenomena in electrocatalysis

    CERN Document Server

    Vayenas, Constantinos G

    2011-01-01

    This volume analyzes and summarizes recent developments and breakthroughs in several key interfacial electrochemical systems in fuel cell electrocatatalysis. The chapters are written by internationally recognized experts or rising stars in electrocatatalysis addressing both the fundamental and practical aspects of several emerging key electrochemical technologies.

  20. Interfacial Properties of Nanoparticle-Surfactant Systems

    OpenAIRE

    Liggieri, Libero; Ravera, Francesca; Santini, Eva; Ferrari, Michele; Miller, R.; Loglio, G.; Dutschk, V.; Whithby, C.; Fornasiero, D.; Ralston, J.

    2009-01-01

    The utilisation of solid micro/nanoparticles particles in association with surfactants represents an attractive route to control drop/bubble coalescence or liquid film stability in foam and emulsion technology. In fact, the transfer/attachment of nanoparticles to liquid interfaces, driven by their partial wettability, strongly modifies the mechanical properties of the interfacial layers. At large surface coverage, particles can build solid-like barriers to coalescence, such as particle networ...

  1. Interfacial models of nerve fiber cytoskeleton.

    OpenAIRE

    Malev, V V; Gromov, D B; Komissarchik YaYu; Brudnaya, M S

    1992-01-01

    A new approach, basing on a resemblance between cytoskeleton structures associated with plasma membranes and interfacial layers of coexisting phases, is proposed. In particular, a lattice model, similar to those of the theory of surface properties of pure liquids and nonelectrolyte solutions (Ono, S., and S. Kondo. 1960. Handbuch der Physik.), has been developed to describe nerve fiber cytoskeleton. The preliminary consideration of the model shows the existence of submembrane cytoskeleton hav...

  2. Dentin-cement Interfacial Interaction: Calcium Silicates and Polyalkenoates

    OpenAIRE

    Atmeh, A.R.; Chong, E. Z.; Richard, G; Festy, F.; Watson, T.F.

    2012-01-01

    The interfacial properties of a new calcium-silicate-based coronal restorative material (Biodentine™) and a glass-ionomer cement (GIC) with dentin have been studied by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), micro-Raman spectroscopy, and two-photon auto-fluorescence and second-harmonic-generation (SHG) imaging. Results indicate the formation of tag-like structures alongside an interfacial layer called the “mineral infiltration zone”, where the alkaline c...

  3. Electrical Resistance Measurements and Microstructural Characterization of the Anode/Interconnect Contact in Simulated Anode-Side SOFC Conditions

    DEFF Research Database (Denmark)

    Harthøj, Anders; Alimadadi, Hossein; Holt, Tobias;

    2015-01-01

    in phase transformation of the steel and in formation of oxides with a poor electrical conductivity in the anode. In this study, the area specific resistance (ASR) of the steel Crofer 22 APU, in contact with a Ni/YSZ anode with and without a tape casted CeO2 barrier layer was measured in simulated SOFC...

  4. Interfacial rheology and emulsion stability in model systems

    International Nuclear Information System (INIS)

    Measurements of thermodynamic interfacial tension σ at a non-equilibrium surfactant adsorption have been made using a pulsed drop rheometer. The pulsed drop rheometer is based on an instantaneous expansion of a water droplet in oil. After perturbation an interfacial relaxation occurs, the interfacial pressure decay is followed as a function of time using a sensitive pressure transducer. The difference in pressure across a curved interface and the interfacial tension are directly related. Interfacial tension decays can be obtained above and below the surfactants CMC. The interfacial tension decays obtained were fitted to known relaxation mechanisms, and found generally to fit diffusional mechanisms. The funnel technique involves expansion of the interface through a funnel, the interfacial tension decays are followed directly. The results were found to be analogous to measurements made by the pulsed drop. Measurements have been made of the interfacial shear viscosity of a polymeric surfactant at the oil / water interface, the interface showed Newtonian-like behaviour. Small nearly monodisperse oil-in-water emulsions were prepared. The parameters involved in their successful preparation have been investigated, the emulsion was characterized by bulk rheology. The instability to salt addition of some systems and small droplet size allowed perikinetic measurements of the coalescing emulsion by photon correlation spectroscopy. Model water-in-oil emulsions were prepared, similar in composition to the interfacial rheology work. These emulsions were investigated in the presence of de-emulsifiers by perikinetic and bulk emulsion stability studies. Mobility vs. potassium chloride concentration data in the thin double layer region has been determined for some model emulsion systems and polystyrene latices. The applicability to the thin double layer electrokinetic theory has been determined for all these systems. (author)

  5. Nb and Ta layer doping effects on the interfacial energetics and electronic properties of LaAlO3/SrTiO3 heterostructure: first-principles analysis.

    Science.gov (United States)

    Nazir, Safdar; Behtash, Maziar; Cheng, Jianli; Luo, Jian; Yang, Kesong

    2016-01-28

    The two-dimensional electron gas (2DEG) formed at the n-type (LaO)(+1)/(TiO2)(0) interface in the polar/nonpolar LaAlO3/SrTiO3 (LAO/STO) heterostructure (HS) has emerged as a prominent research area because of its great potential for nanoelectronic applications. Due to its practical implementation in devices, desired physical properties such as high charge carrier density and mobility are vital. In this respect, 4d and 5d transition metal doping near the interfacial region is expected to tailor electronic properties of the LAO/STO HS system effectively. Herein, we studied Nb and Ta-doping effects on the energetics, electronic structure, interfacial charge carrier density, magnetic moment, and the charge confinements of the 2DEG at the n-type (LaO)(+1)/(TiO2)(0) interface of LAO/STO HS using first-principles density functional theory calculations. We found that the substitutional doping of Nb(Ta) at Ti [Nb(Ta)@Ti] and Al [Nb(Ta)@Al] sites is energetically more favorable than that at La [Nb(Ta)@La] and Sr [Nb(Ta)@Sr] sites, and under appropriate thermodynamic conditions, the changes in the interfacial energy of HS systems upon Nb(Ta)@Ti and Nb(Ta)@Al doping are negative, implying that the formation of these structures is energetically favored. Our calculations also showed that Nb(Ta)@Ti and Nb(Ta)@Al doping significantly improve the interfacial charge carrier density with respect to that of the undoped system, which is because the Nb(Ta) dopant introduces excess free electrons into the system, and these free electrons reside mainly on the Nb(Ta) ions and interfacial Ti ions. Hence, along with the Ti 3d orbitals, the Nb 4d and Ta 5d orbitals also contribute to the interfacial metallic states; accordingly, the magnetic moments on the interfacial Ti ions increase significantly. As expected, the Nb@Al and Ta@Al doped LAO/STO HS systems show higher interfacial charge carrier density than the undoped and other doped systems. In contrast, Nb@Ti and Ta@Ti doped systems may

  6. Kinetic multi-layer model of aerosol surface and bulk chemistry (KM-SUB: the influence of interfacial transport and bulk diffusion on the oxidation of oleic acid by ozone

    Directory of Open Access Journals (Sweden)

    M. Shiraiwa

    2010-04-01

    Full Text Available We present a novel kinetic multi-layer model that explicitly resolves mass transport and chemical reaction at the surface and in the bulk of aerosol particles (KM-SUB. The model is based on the PRA framework of gas-particle interactions (Pöschl-Rudich-Ammann, 2007, and it includes reversible adsorption, surface reactions and surface-bulk exchange as well as bulk diffusion and reaction. Unlike earlier models, KM-SUB does not require simplifying assumptions about steady-state conditions and radial mixing. The temporal evolution and concentration profiles of volatile and non-volatile species at the gas-particle interface and in the particle bulk can be modeled along with surface concentrations and gas uptake coefficients.

    In this study we explore and exemplify the effects of bulk diffusion on the rate of reactive gas uptake for a simple reference system, the ozonolysis of oleic acid particles, in comparison to experimental data and earlier model studies. We demonstrate how KM-SUB can be used to interpret and analyze experimental data from laboratory studies, and how the results can be extrapolated to atmospheric conditions. In particular, we show how interfacial and bulk transport, i.e., surface accommodation, bulk accommodation and bulk diffusion, influence the kinetics of the chemical reaction. Sensitivity studies suggest that in fine air particulate matter oleic acid and compounds with similar reactivity against ozone (carbon-carbon double bonds can reach chemical lifetimes of many hours only if they are embedded in a (semi-solid matrix with very low diffusion coefficients (≤10−10 cm2 s−1. Depending on the complexity of the investigated system, unlimited numbers of volatile and non-volatile species and chemical reactions can be flexibly added and treated with KM-SUB. We propose and intend to pursue the application of KM-SUB as a basis for the development of a detailed master mechanism of aerosol

  7. Kinetic multi-layer model of aerosol surface and bulk chemistry (KM-SUB: the influence of interfacial transport and bulk diffusion on the oxidation of oleic acid by ozone

    Directory of Open Access Journals (Sweden)

    M. Shiraiwa

    2010-01-01

    Full Text Available We present a novel kinetic multi-layer model that explicitly resolves mass transport and chemical reaction at the surface and in the bulk of aerosol particles (KM-SUB. The model is based on the PRA framework of gas-particle interactions (Pöschl et al., 2007, and it includes reversible adsorption, surface reactions and surface-bulk exchange as well as bulk diffusion and reaction. Unlike earlier models, KM-SUB does not require simplifying assumptions about steady-state conditions and radial mixing. The temporal evolution and concentration profiles of volatile and non-volatile species at the gas-particle interface and in the particle bulk can be modeled along with surface concentrations and gas uptake coefficients.

    In this study we explore and exemplify the effects of bulk diffusion on the rate of reactive gas uptake for a simple reference system, the ozonolysis of oleic acid particles, in comparison to experimental data and earlier model studies. We demonstrate how KM-SUB can be used to interpret and analyze experimental data from laboratory studies, and how the results can be extrapolated to atmospheric conditions. In particular, we show how interfacial transport and bulk transport, i.e., surface accommodation, bulk accommodation and bulk diffusion, influence the kinetics of the chemical reaction. Sensitivity studies suggest that in fine air particulate matter oleic acid and compounds with similar reactivity against ozone (C=C double bonds can reach chemical lifetimes of multiple hours only if they are embedded in a (semi-solid matrix with very low diffusion coefficients (≤10−10 cm2 s−1.

    Depending on the complexity of the investigated system, unlimited numbers of volatile and non-volatile species and chemical reactions can be flexibly added and treated with KM-SUB. We propose and intend to pursue the application of KM-SUB as a basis for the development of a detailed master mechanism of

  8. Ultrathin atomic layer deposited ZrO2 coating to enhance the electrochemical performance of Li4Ti5O12 as an anode material

    International Nuclear Information System (INIS)

    Atomic layer deposition (ALD) was used to deposit ZrO2 directly on Li4Ti5O12 electrode to improve its electrochemical performance. The thickness of the deposited ZrO2 was controlled by adjusting ALD cycles from 0 to 1, 2, 5, 10 and 50. The Li4Ti5O12 electrodes with and without ZrO2 coating were characterized by scanning electron microscope, energy dispersive X-ray spectroscopy, high-resolution transmission electron microscope, cyclic voltammetry (CV) and galvanostatic charge-discharge test. The CV result indicated that ZrO2 coating with 2, 5 and 10 ALD cycles could effectively reduce the electrochemical polarization of the Li4Ti5O12 electrode. Charge-discharge test revealed that the Li4Ti5O12 electrodes with 1-, 2- and 5-cycle ZrO2 coating exhibited higher specific capacity, better cycling performance and rate capability than the pristine Li4Ti5O12 in a voltage range of 0.1–2.5 V. However, ZrO2 coating with more than 5 ALD cycles could lead to degraded performance of Li4Ti5O12. Mechanism for the enhanced electrochemical performance of Li4Ti5O12 was explored by electrochemical impedance spectroscopy, and the reason was attributed to the suppressed formation of solid electrolyte interphase and the improved electron transport by ultrathin ZrO2 coating

  9. Anodizing Aluminum with Frills.

    Science.gov (United States)

    Doeltz, Anne E.; And Others

    1983-01-01

    "Anodizing Aluminum" (previously reported in this journal) describes a vivid/relevant laboratory experience for general chemistry students explaining the anodizing of aluminum in sulfuric acid and constrasting it to electroplating. Additions to this procedure and the experiment in which they are used are discussed. Reactions involved are also…

  10. Anodized aluminum on LDEF

    Science.gov (United States)

    Golden, Johnny L.

    1993-01-01

    A compilation of reported analyses and results obtained for anodized aluminum flown on the Long Duration Exposure Facility (LDEF) was prepared. Chromic acid, sulfuric acid, and dyed sulfuric acid anodized surfaces were exposed to the space environment. The vast majority of the anodized surface on LDEF was chromic acid anodize because of its selection as a thermal control coating for use on the spacecraft primary structure, trays, tray clamps, and space end thermal covers. Reports indicate that the chromic acid anodize was stable in solar absorptance and thermal emittance, but that contamination effects caused increases in absorptance on surfaces exposed to low atomic oxygen fluences. There were some discrepancies, however, in that some chromic acid anodized specimens exhibited significant increases in absorptance. Sulfuric acid anodized surfaces also appeared stable, although very little surface area was available for evaluation. One type of dyed sulfuric acid anodize was assessed as an optical baffle coating and was observed to have improved infrared absorptance characteristics with exposure on LDEF.

  11. Simultaneous Use Of Zr And Mg Anodes In XPS

    Science.gov (United States)

    Allgeyer, D. F.; Pratz, E. H.

    1996-01-01

    Improved x-ray source for x-ray photoelectron spectroscopy (XPS) contains both zirconium anode with beryllium window and magnesium anode with aluminum window. Previously unresolvable peaks of electron-energy spectrum become resolvable. Developed specifically for use in analyzing distributions of chemical constituents in surface layers of specimens of 2219 aluminum alloy and in determining the depths of surface oxide layers and relative proportions of aluminum and oxide in layers. Also used to study chemical constituents of surface layers in other material systems - for example, thin oxide films on silicon-based semiconductor devices, oxide films on alloys, and surface layers affecting adhesion of paints or bonding materials.

  12. Electric current characteristic of anodic bonding

    International Nuclear Information System (INIS)

    In this paper, a novel current–time model of anodic bonding is proposed and verified experimentally in order to investigate underlying mechanisms of anodic bonding and to achieve real-time monitoring of bonding procedure. The proposed model provides a thorough explanation for the electric current characteristic of anodic bonding. More significantly, it explains two issues which other models cannot explain. One is the sharp rise in current when a voltage is initially applied during anodic bonding. The other is the unexpected large width of depletion layers. In addition, enlargement of the intimately contacted area during anodic bonding can be obtained from the proposed model, which can be utilized to monitor the bonding process. To verify the proposed model, Borofloat33 glass and silicon wafers were adopted in bonding experiments in SUSS SB6 with five different bonding conditions (350 °C 1200 V; 370 °C 1200 V; 380 °C 1200 V; 380 °C 1000 V; and 380 °C 1400 V). The results indicate that the observed current data highly coincide with the proposed current-time model. For widths of depletion layers, depth profiling using secondary ion mass spectrometry demonstrates that the calculated values by the model are basically consistent with the experimental values as well. (paper)

  13. Extreme interfacial waves

    OpenAIRE

    Grimshaw, R. H. J.; Pullin, D. I.

    1986-01-01

    Numerical solutions are presented for large-amplitude interfacial waves of extreme form on the interface between two fluids of different densities in the Boussinesq approximation. The flow in the lower fluid is irrotational, but the upper fluid may have constant, nonzero vorticity. Only symmetric waves are calculated. The results suggest limiting wave profiles for which separate portions of the interface touch, forming stagnant zones of one fluid imbedded in the other fluid.

  14. Model of interfacial melting

    OpenAIRE

    Mouritsen, Ole G.; Zuckermann, Martin J.

    1987-01-01

    A two-dimensional model is proposed to describe systems with phase transitions which take place in terms of crystalline as well as internal degrees of freedom. Computer simulation of the model shows that the interplay between the two sets of degrees of freedom permits observation of grain-boundary formation and interfacial melting, a nonequilibrium process by which the system melts at the boundaries of a polycrystalline domain structure. Lipid membranes are candidates for systems with pronoun...

  15. Interfacial behavior of asphaltenes.

    Science.gov (United States)

    Langevin, Dominique; Argillier, Jean-François

    2016-07-01

    We review the existing literature on asphaltenes at various types of interfaces: oil-water, air-water, gas-oil and solid-liquid, with more emphasis on the oil-water interfaces. We address the role of asphaltene aggregation, recently clarified for asphaltenes in bulk by the Yen-Mullins model. We discuss the questions of adsorption reversibility and interfacial rheology, especially in connection with emulsion stability. PMID:26498501

  16. Structural comparison of anodic nanoporous-titania fabricated from single-step and three-step of anodization using two paralleled-electrodes anodizing cell

    Directory of Open Access Journals (Sweden)

    Mallika Thabuot

    2016-02-01

    Full Text Available Anodization of Ti sheet in the ethylene glycol electrolyte containing 0.38wt% NH4F with the addition of 1.79wt% H2O at room temperature was studied. Applied potential of 10-60 V and anodizing time of 1-3 h were conducted by single-step and three-step of anodization within the two paralleled-electrodes anodizing cell. Their structural and textural properties were investigated by X-ray diffraction (XRD and scanning electron microscopy (SEM. After annealing at 600°C in the air furnace for 3 h, TiO2-nanotubes was transformed to the higher proportion of anatase crystal phase. Also crystallization of anatase phase was enhanced as the duration of anodization as the final step increased. By using single-step of anodization, pore texture of oxide film was started to reveal at the applied potential of 30 V. Better orderly arrangement of the TiO2-nanotubes array with larger pore size was obtained with the increase of applied potential. The applied potential of 60 V was selected for the three-step of anodization with anodizing time of 1-3 h. Results showed that the well-smooth surface coverage with higher density of porous-TiO2 was achieved using prolonging time at the first and second step, however, discontinuity tube in length was produced instead of the long-vertical tube. Layer thickness of anodic oxide film depended on the anodizing time at the last step of anodization. More well arrangement of nanostructured-TiO2 was produced using three-step of anodization under 60 V with 3 h for each step.

  17. Zinc electrowinning: anode conditioning and current distribution studies

    International Nuclear Information System (INIS)

    In the zinc electrowinning (EW) process, Pb-Ag anodes are widely used. Prior to their use in the EW process, anodes are conditioned to form a stable oxide layer that can evolve O2 without excessive Pb contamination of the cathode and MnO2 precipitation. The most widely used conditioning techniques are: passivation in a KF-H2SO4 electrolysis bath, chemical oxidation in a KMnO4-H2SO4 solution, and sandblasting. In this paper, a comparison of these treatments using flat and corrugated anodes is presented. Laboratory and industrial-scale tests carried out at Cominco's Trail and Cajamarquilla zinc plants indicated that flat anodes should be sandblasted or electrochemically passivated before their use in the Zn electrowinning process. Further, corrugated anodes should be sandblasted or chemically conditioned in a KMnO4-H2SO4 -electrolyte. The beneficial effects of chemical conditioning are lost if the anode is non-corrugated. Flat, chemically conditioned anodes generate up to 10 times more mud than corrugated-chemically conditioned anodes. Because anode mud growth is evenly distributed on sandblasted anodes, short-circuit frequency may decrease and anode life may increase. Sandblasting does not appear to affect anode performance. Parallel to the industrial anode conditioning tests, current distribution measurements were made. Current flow measurements were used to correct troublesome electrodes and/or bad electrical contacts. In Cajamarquilla, this technique was used in four industrial electrowinning cells and energy consumption values lower than 3000 kWh/t Zn were obtained at current efficiencies as high as 95% and at current densities up to 450 A/m2. (author)

  18. INTERFACIAL MASS TRANSPORT IN OXIDE CRYSTAL GROWTH

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ A space high temperature in situobservation instrument (SHITISOI) is dedicated to visualize and record the whole growth process of oxide crystal in high temperature melts and solutions. Model experiments using transparent liquids such as KNbO3,Li2B4O7+KNbO3 were chosen to investigate effects of interracial mass transport in oxide crystal growth. For the scaling of the coupled velocity, heat and concentration fields in KNbO3 crystal growth, a rotating crystal growth process was performed and the widths of interfacial concentration, heat and momentum transition zones (The "boundary layers") are obtained, which are 7.5×10-a, 8.6×10-2 and 4.4×10-1 cm,respectively. Hence one can expect that interfacial concentration gradient will be confined to a narrow layer and in region of major concentration change at the in terface. In order to study a mechanism based on the interfacial mass transport resulting from hydrodynamics, the growth of KNbO3 grain in high temperature Li2B4O7 and KNbO3 solutin was studied. The result shows that the pivotal feature in the KNbO3 crystal growth is the initiated by KNbO3 solute surface tension gra dient which is caused by the slow diffusion of KNbO3 solutes. Direct comparison of the model predictions and experimental observed phenomena demonstrate the predictive capability of this model.

  19. Interfacial Symmetry Control of Emergent Ferromagnetism

    Science.gov (United States)

    Grutter, Alexander; Borchers, Julie; Kirby, Brian; He, Chunyong; Arenholz, Elke; Vailionis, Arturas; Flint, Charles; Suzuki, Yuri

    Atomically precise complex oxide heterostructures provide model systems for the discovery of new emergent phenomena since their magnetism, structure and electronic properties are strongly coupled. Octahedral tilts and rotations have been shown to alter the magnetic properties of complex oxide heterostructures, but typically induce small, gradual magnetic changes. Here, we demonstrate sharp switching between ferromagnetic and antiferromagnetic order at the emergent ferromagnetic interfaces of CaRuO3/CaMnO3 superlattices. Through synchrotron X-ray diffraction and neutron reflectometry, we show that octahedral distortions in superlattices with an odd number of CaMnO3 unit cells in each layer are symmetry mismatched across the interface. In this case, the rotation symmetry switches across the interface, reducing orbital overlap, suppressing charge transfer from Ru to Mn, and disrupting the interfacial double exchange. This disruption switches half of the interfaces from ferromagnetic to antiferromagnetic and lowers the saturation magnetic of the superlattice from 1.0 to 0.5 μB/interfacial Mn. By targeting a purely interfacial emergent magnetic system, we achieve drastic alterations to the magnetic ground state with extremely small changes in layer thickness.

  20. Nonequilibrium interfacial tension during relaxation.

    Science.gov (United States)

    Bier, Markus

    2015-10-01

    The concept of a nonequilibrium interfacial tension, defined via the work required to deform a system such that the interfacial area is changed while the volume is conserved, is investigated theoretically in the context of the relaxation of an initial perturbation of a colloidal fluid towards the equilibrium state. The corresponding general formalism is derived for systems with planar symmetry and applied to fluid models of colloidal suspensions and polymer solutions. It is shown that the nonequilibrium interfacial tension is not necessarily positive, that negative nonequilibrium interfacial tensions are consistent with strictly positive equilibrium interfacial tensions, and that the sign of the interfacial tension can influence the morphology of density perturbations during relaxation. PMID:26565189

  1. An inert metal anode for magnesium electrowinning

    Energy Technology Data Exchange (ETDEWEB)

    Moore, J. F.; Hryn, J. N.; Pellin, M. J.; Calaway, W. F.; Watson, K.

    1999-12-01

    Results from the development of a novel type of anode for electrowinning Mg are reported. A tailored alloy system based on the binary Cu-Al can be made to form a thin alumina layer on its surface that is relatively impervious to attack by the molten chloride melt at high temperature. This barrier is thin enough (5--50 nm) to conduct electrical current without significant IR loss. As the layer slowly dissolves, the chemical potential developed at the surface drives the diffusion of aluminum from the bulk alloy to reform (heal) the protective alumina layer. In this way, an anode that generates Cl{sub 2} (melt electrolysis) and O{sub 2} (wet feed hydrolysis) and no chlorocarbons can be realized. Further, the authors expect the rate of loss of the anode to be dramatically less than the coke-derived carbon anodes typically in use for this technology, leading to substantial cost savings and ancillary pollution control by eliminating coke plant emissions, as well as eliminating chlorinated hydrocarbon emissions from Mg electrowinning cells.

  2. Estimating interfacial thermal conductivity in metamaterials through heat flux mapping

    Energy Technology Data Exchange (ETDEWEB)

    Canbazoglu, Fatih M.; Vemuri, Krishna P.; Bandaru, Prabhakar R., E-mail: pbandaru@ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

    2015-04-06

    The variability of the thickness as well as the thermal conductivity of interfaces in composites may significantly influence thermal transport characteristics and the notion of a metamaterial as an effective medium. The consequent modulations of the heat flux passage are analytically and experimentally examined through a non-contact methodology using radiative imaging, on a model anisotropic thermal metamaterial. It was indicated that a lower Al layer/silver interfacial epoxy ratio of ∼25 compared to that of a Al layer/alumina interfacial epoxy (of ∼39) contributes to a smaller deviation of the heat flux bending angle.

  3. Carbon-supported Ni@NiO/Al2O3 integrated nanocomposite derived from layered double hydroxide precursor as cycling-stable anode materials for lithium-ion batteries

    International Nuclear Information System (INIS)

    Highlights: • Carbon-supported Ni@NiO/Al2O3 nanocomposite was prepared from LDH/C precursor. • Enhanced specific capacity and cycling stability are obtained. • EIS and TEM results provide convincing information underlying the enhancements. -- Abstract: Transition metal oxides (MO) have been widely investigated as promising anode materials for lithium-ion batteries, but suffer from the problems of irreversible capacity loss and poor cycling stability resulting from intrinsic poor conductivity, large volume expansion/contraction during the discharge/charge processes. Despite two main types of effective efforts, i.e., preparing pre-designed nano/microstructures and hybridization with either active or conductive nanomaterials, these approaches have hitherto had difficulties in seeking deliberate nano/microstructural designs and guaranteeing homogeneous interface/chemical distributions of active MO material within the non-active matrix at the nanoscale. Herein, we report a preparation of carbon-supported Ni core @ NiO shell/Al2O3 (C-Ni@NiO/Al2O3) integrated nanocomposite derived from NiAl-layered double hydroxide (NiAl-LDH) single-resource precursor. The combined features of the C-Ni@NiO/Al2O3 nanocomposite involve the uniform dispersion of nanosized Ni@NiO, the conductive carbon support and Ni core, as well as the buffer role of the newly generated non-active Al2O3. Electrochemical evaluation shows that the C-Ni@NiO/Al2O3 nanocomposite maintains much enhanced electrochemical performances and good cycling stability in comparison with the pristine NiO. Results of TEM visualizations and electrochemical impedance spectra provide experimentally convincing rationales of the information of Al2O3 buffer and improved the conductivity underlying the enhanced performances. The route could extend to design and prepare various nanostructured metal oxides with uniform-dispersion components based on the versatility in varying the metal cations of LDH precursors

  4. Operation Characteristics and Ion Beam Distribution of Cylindrical Anode Layer Hall Thruster%圆柱形阳极层霍尔推进器的工作特性与离子束流研究

    Institute of Scientific and Technical Information of China (English)

    许丽; 王世庆

    2012-01-01

    主要对圆柱形阳极层霍尔推进器进行实验研究,得到推进器的工作特性、离子束分布、束流中电子的含量等结果.并且给出圆柱形阳极层霍尔推进器的最佳工作参数:工作电压在700~ 1000V之间,电流在0.15~0.65 A,气体流量低于8ml/min.从离子束流的径向分布可知:高电压、低电流、小气量时离子束的发散角较小.%The structures and the operation characteristics of the cylindrical anode layer Hall thruster were experimentally studied. The ion beam distribution and electron density of the ion beam were evaluated with the lab - built setup , made up of six probes. The impacts of the operation conditions, such as the operating voltage, discharge current, pressure, and gas flow rate, on the operation characteristics were evaluated. The results show that the ion beam divergence angle depends to a varying degree on the operation conditions. For instance, a smaller divergence angle was found to originate from a higher voltage, a lower discharge current and a weaker gas flow rate. The optimized conditions were found to be an operating voltage ranging from 700 to 1000 V, a discharge current in the range of 0.15 to 0.65 A, and a gas flow rate of 8 ml/min.

  5. Microstructural characterization and mechanical property of active soldering anodized 6061 Al alloy using Sn–3.5Ag–xTi active solders

    International Nuclear Information System (INIS)

    Active solders Sn–3.5Ag–xTi varied from x = 0 to 6 wt.% Ti addition were prepared by vacuum arc re-melting and the resultant phase formation and variation of microstructure with titanium concentration were analyzed using X-ray diffraction, optical microscopy and scanning electron microscopy. The Sn–3.5Ag–xTi active solders are used as metallic filler to join with anodized 6061 Al alloy for potential applications of providing a higher heat conduction path. Their joints and mechanical properties were characterized and evaluated in terms of titanium content. The mechanical property of joints was measured by shear testing. The joint strength was very dependent on the titanium content. Solder with a 0.5 wt.% Ti addition can successfully wet and bond to the anodized aluminum oxide layers of Al alloy and posses a shear strength of 16.28 ± 0.64 MPa. The maximum bonding strength reached 22.24 ± 0.70 MPa at a 3 wt.% Ti addition. Interfacial reaction phase and chemical composition were identified by a transmission electron microscope with energy dispersive spectrometer. Results showed that the Ti element reacts with anodized aluminum oxide to form Al3Ti-rich and Al3Ti phases at the joint interfaces. - Highlights: ► Active solder joining of anodized Al alloy needs 0.5 wt.% Ti addition for Sn–3.5Ag. ► The maximum bonding strength occurs at 3 wt.% Ti addition. ► The Ti reacts with anodized Al oxide to form Al3Ti-rich and Al3Ti at joint interface.

  6. Electrically conductive anodized aluminum coatings

    Science.gov (United States)

    Alwitt, Robert S. (Inventor); Liu, Yanming (Inventor)

    2001-01-01

    A process for producing anodized aluminum with enhanced electrical conductivity, comprising anodic oxidation of aluminum alloy substrate, electrolytic deposition of a small amount of metal into the pores of the anodized aluminum, and electrolytic anodic deposition of an electrically conductive oxide, including manganese dioxide, into the pores containing the metal deposit; and the product produced by the process.

  7. Improving Efficiency of Aluminium Sacrificial Anode Using Cold Work Process

    Science.gov (United States)

    Asmara, Y. P.; Siregar, J. P.; Tezara, C.; Ann, Chang Tai

    2016-02-01

    Aluminium is one of the preferred materials to be used as sacrificial anode for carbon steel protection. The efficiency of these can be low due to the formation of oxide layer which passivate the anodes. Currently, to improve its efficiency, there are efforts using a new technique called surface modifications. The objective of this research is to study corrosion mechanism of aluminium sacrificial anode which has been processed by cold work. The cold works are applied by reducing the thickness of aluminium sacrificial anodes at 20% and 40% of thickness reduction. The cathodic protection experiments were performed by immersion of aluminium connected to carbon steel cylinder in 3% NaCl solutions. Visual inspections using SEM had been conducted during the experiments and corrosion rate data were taken in every week for 8 weeks of immersion time. Corrosion rate data were measured using weight loss and linear polarization technique (LPR). From the results, it is observed that cold worked aluminium sacrificial anode have a better corrosion performance. It shows higher corrosion rate and lower corrosion potential. The anodes also provided a long functional for sacrificial anode before it stop working. From SEM investigation, it is shown that cold works have changed the microstructure of anodes which is suspected in increasing corrosion rate and cause de-passivate of the surface anodes.

  8. Surface coatings based on polysilsesquioxanes: solution-processible smooth hole-injection layers for optoelectronic applications.

    Science.gov (United States)

    Kessler, Daniel; Lechmann, Maria C; Noh, Seunguk; Berger, Rüdiger; Lee, Changhee; Gutmann, Jochen S; Theato, Patrick

    2009-07-16

    Optoelectronic devices usually consist of a transparent conductive oxide (TCO) as one electrode. Interfacial engineering between the TCO electrode and the overlying organic layers is an important method for tuning device performance. We introduce poly(methylsilsesquioxane)-poly(N,N-di-4-methylphenylamino styrene) (PMSSQ-PTPA) as a potential hole-injection layer forming material. Spin-coating and thermally induced crosslinking resulted in an effective planarization of the anode interface. HOMO level (-5.6 eV) and hole mobility (1 × 10(-6)  cm(2)  · Vs(-1) ) of the film on ITO substrates were measured by cyclovoltammetry and time-of-flight measurement demonstrating the hole injection capability of the layer. Adhesion and stability for further multilayer built-up could be demonstrated. Contact angle measurements and tape tests after several solvent treatments proved the outstanding film stability. PMID:21638376

  9. Effect of nanoscale patterned interfacial roughness on interfacial toughness.

    Energy Technology Data Exchange (ETDEWEB)

    Zimmerman, Jonathan A.; Moody, Neville Reid; Mook, William M. (University of Minnesota, Minneapolis, MN); Kennedy, Marian S. (Clemson University, Clemson, SC); Bahr, David F. (Washington State University, Pullman, WA); Zhou, Xiao Wang; Reedy, Earl David, Jr.

    2007-09-01

    The performance and the reliability of many devices are controlled by interfaces between thin films. In this study we investigated the use of patterned, nanoscale interfacial roughness as a way to increase the apparent interfacial toughness of brittle, thin-film material systems. The experimental portion of the study measured the interfacial toughness of a number of interfaces with nanoscale roughness. This included a silicon interface with a rectangular-toothed pattern of 60-nm wide by 90-nm deep channels fabricated using nanoimprint lithography techniques. Detailed finite element simulations were used to investigate the nature of interfacial crack growth when the interface is patterned. These simulations examined how geometric and material parameter choices affect the apparent toughness. Atomistic simulations were also performed with the aim of identifying possible modifications to the interfacial separation models currently used in nanoscale, finite element fracture analyses. The fundamental nature of atomistic traction separation for mixed mode loadings was investigated.

  10. Anodic oxidation of benzoquinone using diamond anode.

    Science.gov (United States)

    Panizza, Marco

    2014-01-01

    The anodic degradation of 1,4-benzoquinone (BQ), one of the most toxic xenobiotic, was investigated by electrochemical oxidation at boron-doped diamond anode. The electrolyses have been performed in a single-compartment flow cell in galvanostatic conditions. The influence of applied current (0.5-2 A), BQ concentration (1-2 g dm(-3)), temperature (20-45 °C) and flow rate (100-300 dm(3) h(-1)) has been studied. BQ decay kinetic, the evolution of its oxidation intermediates and the mineralization of the aqueous solutions were monitored during the electrolysis by high-performance liquid chromatograph (HPLC) and chemical oxygen demand (COD) measurements. The results obtained show that the use of diamond anode leads to total mineralization of BQ in any experimental conditions due to the production of oxidant hydroxyl radicals electrogenerated from water discharge. The decay kinetics of BQ removal follows a pseudo-first-order reaction, and the rate constant increases with rising current density. The COD removal rate was favoured by increasing of applied current, recirculating flow rate and it is almost unaffected by solution temperature. PMID:24710725

  11. The impact of the inclination of the anode bottom on anode gas covering in the Hall-Heroult cell

    Energy Technology Data Exchange (ETDEWEB)

    Poncsak, S.; Kiss, L.I.; Perron, A. [Quebec Univ., Chicoutimi, PQ (Canada). Dept. des Sciences Appliquees; Perron, S. [Alcan Arvida Research and Development Centre, Jonquiere, PQ (Canada)

    2006-07-01

    The electrical efficiency and the energy consumption of aluminium electrolysis cells is influenced by carbon dioxide bubbles generated at the anode-bath interface. Electrically isolating these carbon-dioxide bubbles increases the ohmic resistance and ultimately, the energy consumption of the aluminium reduction cell. This study examined the impact of the anode inclination and current density on gas coverings and bath velocity for both carbon dioxide-cryolite and air-water systems. A bubble layer simulator based on a Lagrangian description of the bubble layer was constructed to examine these effect. Since the rate of gas production is determined by the applied current density, anode covering can be decreased only by a faster evacuation of the gas from the inter-electrode space. The curvature of the anode bottom promotes the release of the bubbles thereby decreasing the mean value of the covering. New anodes have a square shape with a flat, horizontal bottom. Inhomogeneous current distribution results in non-uniform anode consumption and the corners become progressively rounded during electrolysis. The curvature increases the interelectrode distance around the corner. Results illustrating the effect of the anode curvature on gas covering were obtained through the use of the bubble layer simulator based on the Lagrangian description.14 refs., 2 tabs., 4 figs.

  12. Nanotube Arrays in Porous Anodic Alumina Membranes

    Institute of Scientific and Technical Information of China (English)

    Liang LI; Naoto KOSHIZAKI; Guanghai LI

    2008-01-01

    This review summarizes the various techniques developed for fabricating nanotube arrays in porous anodic alumina membranes (AAMs). After a brief introduction to the fabrication process of AAMs, taking carbons, metals, semiconductors, organics, biomoleculars, and heterojunctions as typical examples, attention will be focused on the recently established methods to fabricate nanotubes in AAM, including electrochemical deposition, surface sol-gel, modified chemical vapor deposition, atomic layer deposition, and layer-by-layer growth. Every method is demonstrated by one or two reported results. Finally, this review is concluded with some perspectives on the research directions and focuses on the AAM-based nanotubes fields.

  13. Asphaltenes : interfacial aggregates characterization and film structure

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, G.; Argillier, J.F. [Inst. Francais du Petrole, Rueil-Malmaison Cedex (France); Langevin, D. [Univ. Paris-Sud, Orsay Cedex (France). Laboratoire de Physique des Solides

    2008-07-01

    An understanding of stability mechanisms of crude oil emulsions is necessary for controlling and improving heavy oil production. The properties of the amphiphilic film that surrounds the droplets influence the behaviour of emulsions. This study examined the complex composition of asphaltenes, resins and naphtenic acids found in crude oil using a combination of techniques, such as measurement of dynamic interfacial tension and rheology of water; and modelling the oil interface where asphaltenes or naphthenic acids are dissolved. The study revealed the properties of the films. The amount of adsorbed asphaltene at the interface was determined through small-angle neutrons scattering (SANS) measurements, in which the structure of the interfacial layer and aggregates characteristics were obtained, along with UV-VIS experiments. The study showed that different parameters have a significant influence on interfacial structure and film properties, and therefore on emulsions behaviour. The parameters include naphthenic acid/asphaltene ratio, molecular weight of the naphtenic acid, pH and ionic strength of the aqueous phase. Some correlation between microscopic properties and macroscopic behaviour were obtained using stability tests on emulsions.

  14. Microstructure and optical appearance of anodized friction stir processed Al - Metal oxide surface composites

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Jensen, Flemming; Bordo, Kirill;

    2014-01-01

    oxide particles which will influence the scattering of light. This paper presents the investigations on relation between microstructure of the FSP zone and optical appearance of the anodized layer due to incorporation of metal oxide particles and modification of the oxide particles due to the anodizing...... process. The effect of anodizing parameters on the optical appearance of the anodized surface was studied. Characterization was performed using FIB-SEM and TEM. The surface appearance was analysed using spectrophotometry technique which measures the diffuse and total reflectance of the surface. The...... appearance of the anodized surface changed from dark to bright upon increasing the anodizing voltage. Particles in the FSP zone were partially or completely modified during the anodizing process and modified the morphology of the surrounding anodized Al matrix which has a clear influence on the mechanism of...

  15. Preparation and Properties of Al-Ni Composite Anodic Films on Aluminum Surface

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xuhui; YE Hao; ZHANG Xiaofeng; ZUO Yu

    2012-01-01

    Ni element was introduced to aluminum surface by a simple chemical immersion method,and Al-Ni composite anodic films were obtained by following anodizing.The morphology,structure and composition of the Al-Ni anodic films were examined by scanning electron microscopy (SEM),energy disperse spectroscopy (EDS) and atomic force microscopy(AFM).The electrochemical behaviors of the films were studied by means of polarization measurement and electrochemical impedance spectroscopy (EIS).The experimental results show that the A1-Ni composite anodic film is more compact with smaller pore diameters than that of the Al anodic film.The introduction of nickel increases the impedances of both the barrier layer and the porous layer of the anodic films.In NaCl solutions,the Al-Ni composite anodic films show higher impedance values and better corrosion resistance.

  16. Room Temperature Anodization of Aluminum at Low Voltage

    International Nuclear Information System (INIS)

    Membranes with nanometer-scale features have many applications, such as in optics, electronics, catalysis, selective molecule separation, filtration and purification, bio sensing, and single-molecule detection. Anodization process was conducted using 15, 20, 30 and 35% by volume phosphoric acid. Results showed that Porous Anodized Aluminum (PAA) with ideal nano pore arrays can be fabricated at room temperature by one-step anodization on high purity aluminum foil at 5 V. Morphology of the PAA was characterized by scanning electron microscopy (SEM). The electrochemical behavior of anodized aluminum was studied in 0.1 M Na2SO4 solutions using electrochemical impedance spectroscopy (EIS). The highest resistance of the porous layer (Rp) was detected for the samples anodized in 20% phosphoric acid

  17. Surface and interfacial creases in a bilayer tubular soft tissue

    Science.gov (United States)

    Razavi, Mir Jalil; Pidaparti, Ramana; Wang, Xianqiao

    2016-08-01

    Surface and interfacial creases induced by biological growth are common types of instability in soft biological tissues. This study focuses on the criteria for the onset of surface and interfacial creases as well as their morphological evolution in a growing bilayer soft tube within a confined environment. Critical growth ratios for triggering surface and interfacial creases are investigated both analytically and numerically. Analytical interpretations provide preliminary insights into critical stretches and growth ratios for the onset of instability and formation of both surface and interfacial creases. However, the analytical approach cannot predict the evolution pattern of the model after instability; therefore nonlinear finite element simulations are carried out to replicate the poststability morphological patterns of the structure. Analytical and computational simulation results demonstrate that the initial geometry, growth ratio, and shear modulus ratio of the layers are the most influential factors to control surface and interfacial crease formation in this soft tubular bilayer. The competition between the stretch ratios in the free and interfacial surfaces is one of the key driving factors to determine the location of the first crease initiation. These findings may provide some fundamental understanding in the growth modeling of tubular biological tissues such as esophagi and airways as well as offering useful clues into normal and pathological functions of these tissues.

  18. In-situ spectroscopic studies and interfacial engineering on FeSe/oxide heterostructures: Insights on the interfacial superconductivity

    Science.gov (United States)

    Peng, Rui; Xu, Hai-Chao; Feng, Dong-Lai

    2015-11-01

    The discovery of high temperature superconductivity in single-layer FeSe/SrTiO3 provides a new platform for exploring superconductivity and pursuing higher Tc (superconducting transition temperature) through fabricating artificial heterostructures. In this paper, we review the recent progress in studying and tuning the interfacial superconductivity in single-layer FeSe, through the combined in-situ spectroscopic studies and atomic-scale engineering. By fabricating artificial heterostructures, various interfacial factors were tuned, and the corresponding evolutions of electronic structure and superconducting gap behavior were investigated. These studies enrich the current understanding on the interfacial superconductivity, and provide clues for further enhancing Tc through interface engineering. Project supported by the National Natural Science Foundation of China and the National Basic Research Program of China (Grant Nos. 2012CB921402, 2011CB921802, and 2011CBA00112).

  19. Improvement in direct methanol fuel cell performance by treating the anode at high anodic potential

    Science.gov (United States)

    Joghee, Prabhuram; Pylypenko, Svitlana; Wood, Kevin; Corpuz, April; Bender, Guido; Dinh, Huyen N.; O'Hayre, Ryan

    2014-01-01

    This work investigates the effect of a high anodic potential treatment protocol on the performance of a direct methanol fuel cell (DMFC). DMFC membrane electrode assemblies (MEAs) with PtRu/C (Hi-spec 5000) anode catalyst are subjected to anodic treatment (AT) at 0.8 V vs. DHE using potentiostatic method. Despite causing a slight decrease in the electrochemical surface area (ECSA) of the anode, associated with ruthenium dissolution, AT results in significant improvement in DMFC performance in the ohmic and mass transfer regions and increases the maximum power density by ∼15%. Furthermore, AT improves the long-term DMFC stability by reducing the degradation of the anode catalyst. From XPS investigation, it is hypothesized that the improved performance of AT-treated MEAs is related to an improved interface between the catalyst and Nafion ionomer. Among potential explanations, this improvement may be caused by incorporation of the ionomer within the secondary pores of PtRu/C agglomerates, which generates a percolating network of ionomer between PtRu/C agglomerates in the catalyst layer. Furthermore, the decreased concentration of hydrophobic CF2 groups may help to enhance the hydrophilicity of the catalyst layer, thereby increasing the accessibility of methanol and resulting in better performance in the high current density region.

  20. Effect of aluminium alloy surface heterogeneities on anodic layer growth and properties; Efecto de las heterogeneidades superficiales de las aleaciones de aluminio sobre el crecimiento y propiedades de las capas anodicas

    Energy Technology Data Exchange (ETDEWEB)

    Bartolome, M. J.; Feliu, J.V.; Lopez, E.; Gonzalez, J. A.; Feliu, S.

    2007-07-01

    In the present work, X-ray photoelectron spectroscopy (XPS) is used to study sealed and unsealed anodic coatings obtained on pure-Al and on Al-Cu, Al-Mg-Si and Al-Mg alloys. In general, the sealing process is seen to produce a significant increase in the O/A ratio in the anodic coatings. this increase is more considerable with the Al-Cu and Al-Mg alloys than with the pure Al and the Al-Mg-Si alloy, perhaps due to the greater porosity of the coatings obtained on the former. An attempt is made to establish possible relationships between anodic film characteristics and surface heterogeneities, which also act in the phase prior to anodising. According to the results of this work, these heterogeneities affect the degree of dissolution of the metallic substrate during the anodising operation. (Author)

  1. The influence of Hall drift to the ionization efficiency of anode layer Hall plasma accelerator%霍尔漂移对阳极层霍尔等离子体加速器电离效率的影响

    Institute of Scientific and Technical Information of China (English)

    耿少飞; 唐德礼; 邱孝明; 聂军伟; 于毅军

    2012-01-01

    The Hall drift of electrons in anode layer plasma accelerator is analyzed based on Lorentz transformation.It is shown that Hall drift does not exist always in the cross-field.If the ratio of E to B is lager than light speed,Hall drift will disappear.The further analysis shows that the Hall drift is not always in the form of gyration.It is also in the forms of wave and straight line,depending on electric-magnetic field configuration and initial energy of electrons.The electric-magnetic configuration determines the speed of drift,and then affects electron energy.This can determine the ionization efficiency in discharge.A numerical simulation using the Particle-in-Cell method is performed.The result indicates that a nice ratio of E and B will produce high ionization efficiency(for argon,this value is about 4×10~6).This value will change with working gas according to the ionization cross section determined by electron energy.%以洛伦兹变换方法为基础,分析了阳极层霍尔等离子体加速器中电子的霍尔漂移,结果表明在交叉场中,霍尔漂移并不总是存在的,E/B的比值大于光速时,霍尔漂移将不存在.进一步的分析表明,霍尔漂移也并不总是回旋形式的,不同的电磁场配置以及不同的电子初始能量将带来不同形式的漂移,包括回旋形式,波浪线形式,甚至直线形式.电磁场的配置也决定着霍尔漂移的速度,在很大程度上影响着电子的能量,这就决定了放电时的电离效率.对不同电磁场配置进行数值模拟发现,合理的电磁场比值能够得到更好的电离效率(对于氩,这个数值大约为4×10~6).不同的气体,根据其电离碰撞截面与电子能量的关系,都有不同的合理比值.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Kashish [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309 (United States); Routkevitch, Dmitri; Varaksa, Natalia [InRedox, Longmont, Colorado 80544 (United States); George, Steven M., E-mail: Steven.George@Colorado.Edu [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309 and Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States)

    2016-01-15

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

  3. Laser-Ultrasonic Measurement of Elastic Properties of Anodized Aluminum Coatings

    Science.gov (United States)

    Singer, F.

    Anodized aluminum oxide plays a great role in many industrial applications, e.g. in order to achieve greater wear resistance. Since the hardness of the anodized films strongly depends on its processing parameters, it is important to characterize the influence of the processing parameters on the film properties. In this work the elastic material parameters of anodized aluminum were investigated using a laser-based ultrasound system. The anodized films were characterized analyzing the dispersion of Rayleigh waves with a one-layer model. It was shown that anodizing time and temperature strongly influence Rayleigh wave propagation.

  4. The effect of compression on natural graphite anode performance and matrix conductivity

    OpenAIRE

    Striebel, K.A.; A. Sierra; Shim, J.; Wang, C.-W.; Sastry, A.M.

    2004-01-01

    Anodes for lithium-ion cells were constructed from three types of natural graphite, two coated spherical and one flaky. Anode samples were compressed from 0 to 300 kg/cm2 and studied in half-cells to study the relations between anode density, SEI formation and anode cyclability. The C/25 formation of the SEI layer was found to depend on the nature of the graphite and the anode density. Compression of the uncoated graphite lead to an increased conductivity, but only slight improvements i...

  5. Ultra-structural evaluation of an anodic oxidated titanium dental implant.

    Science.gov (United States)

    Yamagami, Akiyoshi; Nagaoka, Noriyuki; Yoshihara, Kumiko; Nakamura, Mariko; Shirai, Hajime; Matsumoto, Takuya; Suzuki, Kazuomi; Yoshida, Yasuhiro

    2014-01-01

    Anodic oxidation is used for the surface treatment of commercial implants to improve their functional properties for clinical success. Here we conducted ultrastructural and chemical investigations into the micro- and nanostructure of the anodic oxide film of a titanium implant. The anodic oxidized layer of a Ti6Al4V alloy implant was examined ultrastructurally by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). They were also analyzed using energy dispersive X-ray spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS). The TEM revealed that the oxide layer of the Ti6Al4V implant prepared through anodic oxidation was separated into two layers. Al and V were not present on the top surface of the anodic oxide. This can be attributed to the biocompatibility of the anodic oxidized Ti6Al4V alloy implant, because the release of harmful metal ions such as Al and V can be suppressed by the biocompatibility. PMID:25483382

  6. Engineering of highly ordered TiO2 nanopore arrays by anodization

    Science.gov (United States)

    Wang, Huijie; Huang, Zhennan; Zhang, Li; Ding, Jie; Ma, Zhaoxia; Liu, Yong; Kou, Shengzhong; Yang, Hangsheng

    2016-07-01

    Finite element analysis was used to simulate the current density distributions in the TiO2 barrier layer formed at the initial stage of Ti anodization. The morphology modification of the barrier layer was found to induce current density distribution change. By starting the anodization with proper TiO2 barrier layer morphology, the current density distribution can be adjusted to favor the formation of either nanotube arrays or nanopore arrays of anodic TiO2. We also found that the addition of sodium acetate into the electrolyte suppressed both the field-assisted chemical dissolution of TiO2 and the TiF62- hydrolysis induced TiO2 deposition during anodization, and thus further favored the nanopore formation. Accordingly, highly ordered anodic TiO2 nanopore arrays, similar to anodic aluminum oxide nanopore arrays, were successfully prepared.

  7. Effect of processing on structural features of anodic aluminum oxides

    Science.gov (United States)

    Erdogan, Pembe; Birol, Yucel

    2012-09-01

    Morphological features of the anodic aluminum oxide (AAO) templates fabricated by electrochemical oxidation under different processing conditions were investigated. The selection of the polishing parameters does not appear to be critical as long as the aluminum substrate is polished adequately prior to the anodization process. AAO layers with a highly ordered pore distribution are obtained after anodizing in 0.6 M oxalic acid at 20 °C under 40 V for 5 minutes suggesting that the desired pore features are attained once an oxide layer develops on the surface. While the pore features are not affected much, the thickness of the AAO template increases with increasing anodization treatment time. Pore features are better and the AAO growth rate is higher at 20 °C than at 5 °C; higher under 45 V than under 40 V; higher with 0.6 M than with 0.3 M oxalic acid.

  8. Impact of La{sub 2}O{sub 3} interfacial layers on InGaAs metal-oxide-semiconductor interface properties in Al{sub 2}O{sub 3}/La{sub 2}O{sub 3}/InGaAs gate stacks deposited by atomic-layer-deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C.-Y., E-mail: cychang@mosfet.t.u-tokyo.ac.jp; Takenaka, M.; Takagi, S. [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0032 (Japan); JST-CREST, K' s Gobancho, 7 Gobancho, Chiyoda-ku, Tokyo 102-0076 (Japan); Ichikawa, O.; Osada, T.; Hata, M.; Yamada, H. [JST-CREST, K' s Gobancho, 7 Gobancho, Chiyoda-ku, Tokyo 102-0076 (Japan); Sumitomo Chemical Co. Ltd., 6 Kitahara, Tsukuba, Ibaraki 300-3294 (Japan)

    2015-08-28

    We examine the electrical properties of atomic layer deposition (ALD) La{sub 2}O{sub 3}/InGaAs and Al{sub 2}O{sub 3}/La{sub 2}O{sub 3}/InGaAs metal-oxide-semiconductor (MOS) capacitors. It is found that the thick ALD La{sub 2}O{sub 3}/InGaAs interface provides low interface state density (D{sub it}) with the minimum value of ∼3 × 10{sup 11} cm{sup −2} eV{sup −1}, which is attributable to the excellent La{sub 2}O{sub 3} passivation effect for InGaAs surfaces. It is observed, on the other hand, that there are a large amount of slow traps and border traps in La{sub 2}O{sub 3}. In order to simultaneously satisfy low D{sub it} and small hysteresis, the effectiveness of Al{sub 2}O{sub 3}/La{sub 2}O{sub 3}/InGaAs gate stacks with ultrathin La{sub 2}O{sub 3} interfacial layers is in addition evaluated. The reduction of the La{sub 2}O{sub 3} thickness to 0.4 nm in Al{sub 2}O{sub 3}/La{sub 2}O{sub 3}/InGaAs gate stacks leads to the decrease in hysteresis. On the other hand, D{sub it} of the Al{sub 2}O{sub 3}/La{sub 2}O{sub 3}/InGaAs interfaces becomes higher than that of the La{sub 2}O{sub 3}/InGaAs ones, attributable to the diffusion of Al{sub 2}O{sub 3} through La{sub 2}O{sub 3} into InGaAs and resulting modification of the La{sub 2}O{sub 3}/InGaAs interface structure. As a result of the effective passivation effect of La{sub 2}O{sub 3} on InGaAs, however, the Al{sub 2}O{sub 3}/10 cycle (0.4 nm) La{sub 2}O{sub 3}/InGaAs gate stacks can realize still lower D{sub it} with maintaining small hysteresis and low leakage current than the conventional Al{sub 2}O{sub 3}/InGaAs MOS interfaces.

  9. Cold welding of organic light emitting diode: Interfacial and contact models

    Science.gov (United States)

    Asare, J.; Adeniji, S. A.; Oyewole, O. K.; Agyei-Tuffour, B.; Du, J.; Arthur, E.; Fashina, A. A.; Zebaze Kana, M. G.; Soboyejo, W. O.

    2016-06-01

    This paper presents the results of an analytical and computational study of the contacts and interfacial fracture associated with the cold welding of Organic Light Emitting diodes (OLEDs). The effects of impurities (within the possible interfaces) are explored for contacts and interfacial fracture between layers that are relevant to model OLEDs. The models are used to study the effects of adhesion, pressure, thin film layer thickness and dust particle modulus (between the contacting surfaces) on contact profiles around impurities between cold-welded thin films. The lift-off stage of thin films (during cold welding) is then modeled as an interfacial fracture process. A combination of adhesion and interfacial fracture theories is used to provide new insights for the design of improved contact and interfacial separation during cold welding. The implications of the results are discussed for the design and fabrication of cold welded OLED structures.

  10. Modelling the initial stage of porous alumina growth during anodization

    Science.gov (United States)

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

    2013-05-01

    Artificially on the surface of aluminum there may be build a thick layer of Al2O3, which has a porous structure. In this paper we present a model of growth of porous alumina in the initial stage of anodizing, identifying dependencies anodizing parameters on the rate of growth of the film and the distance between the pores and as a result of the created model equations were found for changes in the disturbance of alumina for the initial stage of anodizing aluminum oxide porous border aluminum-alumina and alumina-electrolyte, with the influence of surface diffusion of aluminum oxide.

  11. In situ characterization of nanoscale catalysts during anodic redox processes

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Renu [National Institute of Standards and Technology; Crozier, Peter [Arizona State University; Adams, James [Arizona State University

    2013-09-19

    Controlling the structure and composition of the anode is critical to achieving high efficiency and good long-term performance. In addition to being a mixed electronic and ionic conductor, the ideal anode material should act as an efficient catalyst for oxidizing hydrogen, carbon monoxide and dry hydrocarbons without de-activating through either sintering or coking. It is also important to develop novel anode materials that can operate at lower temperatures to reduce costs and minimized materials failure associated with high temperature cycling. We proposed to synthesize and characterize novel anode cermets materials based on ceria doped with Pr and/or Gd together with either a Ni or Cu metallic components. Ceria is a good oxidation catalyst and is an ionic conductor at room temperature. Doping it with trivalent rare earths such as Pr or Gd retards sintering and makes it a mixed ion conductor (ionic and electronic). We have developed a fundamental scientific understanding of the behavior of the cermet material under reaction conditions by following the catalytic oxidation process at the atomic scale using a powerful Environmental Scanning Transmission Electron Microscope (ESTEM). The ESTEM allowed in situ monitoring of structural, chemical and morphological changes occurring at the cermet under conditions approximating that of typical fuel-cell operation. Density functional calculations were employed to determine the underlying mechanisms and reaction pathways during anode oxidation reactions. The dynamic behavior of nanoscale catalytic oxidation of hydrogen and methane were used to determine: ? Fundamental processes during anodic reactions in hydrogen and carbonaceous atmospheres ? Interfacial effects between metal particles and doped ceria ? Kinetics of redox reaction in the anode material

  12. Formation and Morphology of Anodic Oxide Films of Ti

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The morphology and structure of the oxide films of Ti in H3PO4 were investigated by galvanostatic anodization, SEM and XRD. The oxide film grew from some pores in the grooves to layered microdomains as increasing anodizing voltage. The crystallinity of the oxide films decreased with the increase of the concentration of the electrolyte. The model has been proposed for the growth of the oxide films by two steps, i.e. by uniform thickening and by local deposition.

  13. Efficient synthesis of interfacially polymerized membranes for solvent resistant nanofiltration

    OpenAIRE

    Hermans, Sanne; Dom, Elke; Mariën, Hanne; Koeckelberghs, Guy; Vankelecom, Ivo

    2015-01-01

    Thin film composite (TFC) membranes are used worldwide in aqueous applications. They mostly consist of a polyamide top-layer put on a polysulfone support via interfacial polymerization. Due to their thin and dense selective layer, these membranes are also interesting for filtrations in organic solutions. Polysulfone should then be replaced by a more solvent resistant material. The synthesis of solvent resistant nanofiltration TFC membranes via a newly developed method is reported: phase inver...

  14. Homogeneous Cu2ZnSnSe4 nanocrystals/graphene oxide nanocomposites as hole transport layer for polymer solar cells

    Science.gov (United States)

    Tan, Licheng; Zhang, Yan; Chen, Yiwang; Chen, Yufeng

    2015-02-01

    Homogeneous Cu2ZnSnSe4 nanocrystals/graphene oxide (CZTSe@GO) nanocomposite as hole transport layer (HTL) applied in polymer solar cells has been fabricated through a simple and solution-processed strategy, which not only arrests the aggregation of nanoparticles caused by ligand-exchanging, but also guarantees the intimate interfacial contact between graphene oxide and semiconductor nanocrystals. Comparing with Cu2ZnSnSe4 nanocrystals, the optimization of interfacial charge carrier transfer pathways for CZTSe@GO nanocomposites makes it more suitable as HTL which shows enhanced charge carrier transport and electron-blocking capacity, and well-matched work function facilitating collection of charges to anode. Besides, it also affords an efficient way to manufacture multifunctional nanocomposites based on nanocrystals.

  15. Interfacial Properties Modification of Carbon Fiber/ Polyarylacetylene Composites

    Institute of Scientific and Technical Information of China (English)

    FU Hong-jun; MA Chong-qi; KUANG Nai-hang; LUAN Shi-lin

    2007-01-01

    This work was dedicated to performing surface oxidation and coating treatments on carbon fibers (CF) and investigating the changes of fiber surface properties after these treatments, including surface composition, relative volume of functional groups, and surface topography with X-ray photoelectron spectroscopy (XPS) and atom force microscopy (AFM) technology. The results show that,after oxidation treatments, interfacial properties between CF and non-polar polyarylacetylene (PAA) resin are remarkably modified by removing weak surface layers and increasing fiber surface roughness. Coating treatment by high char phenolic resin solution after oxidation makes interface of CF/PAA composites to be upgraded and the interfacial properties further bettered.

  16. Double anodization experiments in tantalum

    Energy Technology Data Exchange (ETDEWEB)

    Albella, J.M.; Fernandez, M.; Gomez-Aleixandre, C.; Martinez-Duart, J.M.; Montero, I.

    1985-10-01

    Based on our previous model of anodization, a new formula is given for the relation between the breakdown voltage V /SUB B/ during the anodic oxidation of tantalum and the anodization parameters. The formula predicts the well known diminution of V /SUB B/ with the logarithm of the electrolyte concentration. The model also explains the experimentally-observed fact that V /SUB B/ is solely determined by the latter electrolyte in double anodization experiments.

  17. Photoluminescence emission of nanoporous anodic aluminum oxide films prepared in phosphoric acid

    Science.gov (United States)

    Nourmohammadi, Abolghasem; Asadabadi, Saeid Jalali; Yousefi, Mohammad Hasan; Ghasemzadeh, Majid

    2012-12-01

    The photoluminescence emission of nanoporous anodic aluminum oxide films formed in phosphoric acid is studied in order to explore their defect-based subband electronic structure. Different excitation wavelengths are used to identify most of the details of the subband states. The films are produced under different anodizing conditions to optimize their emission in the visible range. Scanning electron microscopy investigations confirm pore formation in the produced layers. Gaussian analysis of the emission data indicates that subband states change with anodizing parameters, and various point defects can be formed both in the bulk and on the surface of these nanoporous layers during anodizing.

  18. Dynamics of interfacial pattern formation

    Science.gov (United States)

    Ben-Jacob, E.; Goldenfeld, N.; Langer, J. S.; Schon, G.

    1983-01-01

    A phenomenological model of dendritic solidification incorporating interfacial kinetics, crystalline anisotropy, and a local approximation for the dynamics of the thermal diffusion field is proposed. The preliminary results are in qualitative agreement with natural dendrite-like pattern formation.

  19. The Microstructure and Capacitance Characterizations of Anodic Titanium Based Alloy Oxide Nanotube

    OpenAIRE

    Po Chun Chen; Sheng Jen Hsieh; Chien Chon Chen; Jun Zou

    2013-01-01

    This paper presents a simple anodization process to fabricate ordered nanotubes (NTs) of titanium and its alloys (Ti-Mo and Ti-Ta). TiO2, MoO3, and Ta2O5 are high dielectric constant materials for ultracapacitor application. The anodic titanium oxide contains a compact layer on the NT film and a barrier layer under the NT film. However, the microstructure of oxide films formed by anodic Ti-Mo and Ti-Ta alloys contains six layers, including a continuous compact layer, a continuous partial poro...

  20. Inert Anode Report

    Energy Technology Data Exchange (ETDEWEB)

    none,

    1999-07-01

    This ASME report provides a broad assessment of open literature and patents that exist in the area of inert anodes and their related cathode systems and cell designs, technologies that are relevant for the advanced smelting of aluminum. The report also discusses the opportunities, barriers, and issues associated with these technologies from a technical, environmental, and economic viewpoint.

  1. Anodes for alkaline electrolysis

    Science.gov (United States)

    Soloveichik, Grigorii Lev

    2011-02-01

    A method of making an anode for alkaline electrolysis cells includes adsorption of precursor material on a carbonaceous material, conversion of the precursor material to hydroxide form and conversion of precursor material from hydroxide form to oxy-hydroxide form within the alkaline electrolysis cell.

  2. 带有Si3N4薄膜的玻璃-硅-玻璃三层结构的阳极键合%Anodic bonding of glass-silicon-glass three-layer structure with Si3N4 thin film

    Institute of Scientific and Technical Information of China (English)

    林智鑫; 王盛贵; 刘琦; 曾毅波; 郭航

    2013-01-01

    为了获得高品质的带有Si3N4薄膜三层(玻璃-硅-玻璃)的阳极键合结构,对阳极键合的相关工艺参数进行了研究;设计搭建了实验平台并采用点阴极,以实时观察键合界面是否达到同形质的黑色从而判断阳极键合质量,对键合后的样品进行拉力测试,研究表明:当采用键合温度为400℃,电压为1200V,压力为450Pa,可获得键合面积大于90%的带有Si3N4薄膜的三层阳极键合结构.%In order to obtain high quality of anodic bonding structure of glass-silicon-glass with Si3N4 thin film,related process parameters of anodic bonding is researched.Design and build up experimental platform and use point cathode to real-time observe whether if the bonding interface is black of the same character so as to judge quality of anodic bonding,and bonded samples are tested on tension.The research show that more than 90% wafer area can be obtained for glass-silicon-silicon three-layer anodic bonding with Si3N4 structure when the voltage and pressure is 1200 V and 450 Pa respectively,at 400℃.

  3. The anodizing behavior of aluminum in malonic acid solution and morphology of the anodic films

    Science.gov (United States)

    Ren, Jianjun; Zuo, Yu

    2012-11-01

    The anodizing behavior of aluminum in malonic acid solution and morphology of the anodic films were studied. The voltage-time response for galvanostatic anodization of aluminum in malonic acid solution exhibits a conventional three-stage feature but the formation voltage is much higher. With the increase of electrolyte concentration, the electrolyte viscosity increases simultaneously and the high viscosity decreases the film growth rate. With the concentration increase of the malonic acid electrolyte, the critical current density that initiates local "burning" on the sample surface decreases. For malonic acid anodization, the field-assisted dissolution on the oxide surface is relatively weak and the nucleation of pores is more difficult, which results in greater barrier layer thickness and larger cell dimension. The embryo of the porous structure of anodic film has been created within the linear region of the first transient stage, and the definite porous structure has been established before the end of the first transient stage. The self-ordering behavior of the porous film is influenced by the electrolyte concentration, film thickness and the applied current density. Great current density not only improves the cell arrangement order but also brings about larger cell dimension.

  4. Solid/liquid interfacial free energies in binary systems

    Science.gov (United States)

    Nason, D.; Tiller, W. A.

    1973-01-01

    Description of a semiquantitative technique for predicting the segregation characteristics of smooth interfaces between binary solid and liquid solutions in terms of readily available thermodynamic parameters of the bulk solutions. A lattice-liquid interfacial model and a pair-bonded regular solution model are employed in the treatment with an accommodation for liquid interfacial entropy. The method is used to calculate the interfacial segregation and the free energy of segregation for solid-liquid interfaces between binary solutions for the (111) boundary of fcc crystals. The zone of compositional transition across the interface is shown to be on the order of a few atomic layers in width, being moderately narrower for ideal solutions. The free energy of the segregated interface depends primarily upon the solid composition and the heats of fusion of the component atoms, the composition difference of the solutions, and the difference of the heats of mixing of the solutions.

  5. 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.

  6. First-principles studies of interfacial chemistry in negative electrodes for lithium ion battery applications

    OpenAIRE

    Greeley, Jeffrey

    2014-01-01

    Silicon is a promising alternative to graphite as an anode material for lithium-ion batteries due to its enhanced safety and significantly higher theoretical capacity. Drastic volume changes in silicon during lithiation and delithiation cycles, however, hinder cyclability and capacity retention. Most strategies for improving the cyclability of silicon involve the engineering of interfacial chemistry and nanoscale architectures, and to further these efforts, fundamental insights into lithiatio...

  7. Protein adsorption and interfacial rheology interfering in dilatational experiment

    Science.gov (United States)

    Rühs, P. A.; Scheuble, N.; Windhab, E. J.; Fischer, P.

    2013-05-01

    The static and dilatational response of β-lactoglobulin fibrils and native β-lactoglobulin (monomers) at water-air and water-oil interfaces (pH 2) was measured using the pendant drop method. The resulting adsorption behavior and viscoelasticity is dependent of concentration and adsorption time. The interfacial pressure of the β-lactoglobulin fibrils obtained in static measurements was 16-18 mN/m (against air) and 7 mN/m (against oil) for all concentrations. With higher concentrations, faster adsorption kinetics and slightly higher interfacial and surface pressure is achieved but did not lead to higher viscoelastic moduli. The transient saturation of the interface is similar for both the fibril solution and the monomers, however the fibril solution forms a strong viscoelastic network. To evaluate the superimposed adsorption behavior and rheological properties, the formed interfacial layer was subjected to dilatational experiments, which were performed by oscillating the surface area of the drop in sinusoidal and sawtooth (diagonal) deformation manner. The sinusoidal oscillations (time depended area deformation rate) result in a complex interfacial tension behavior against air and oil interfaces and show remarkable differences during compression and expansion as emphasized by Lissajous figures. For diagonal (constant area deformation rate) experiments, a slight bending of the interfacial tension response was observed at low frequencies emphasizing the influence of protein adsorption during rheological measurements.

  8. Analysis of the electrochemical performance of MoNi-CeO2 cermet as anode material for solid oxide fuel cell. Part I. H2, CH4 and H2/CH4 mixtures as fuels

    Science.gov (United States)

    Escudero, M. J.; Gómez de Parada, I.; Fuerte, A.; Serrano, J. L.

    2014-05-01

    This paper investigates the catalytic activity and the electrochemical performance of bimetallic formulation combining Mo and Ni with CeO2 (MoNi-Ce) in relation its potential use as anode material for SOFC. The catalytic properties were evaluated for methane partial oxidation as function of temperature and the carbon deposition on the anode surface was analysed by TG-MS. A conversion of 12.8% was reached for partial methane oxidation at 850 °C as well as a high coke resistance. The electrochemical performance was studied in a single cell with La0.58Sr0.4Fe0.8Co0.2O3-δ (LSCF) as cathode, La0.9Sr0.1Ga0.8Mg0.2O2.85 (LSGM) as electrolyte and MoNi-Ce as anode. A thin buffer layer of La0.4Ce0.6O4-δ (LCD) between anode and electrolyte was used to avoid possible interfacial reactions. The cell was tested in different humidified fuels (H2, CH4 and H2/CH4 mixtures) and static air at 750, 800 and 850 °C. The electrochemical behaviour was evaluated by current-voltage curves, impedance spectroscopy and load demand. Stability tests were also performed in pure CH4 at each studied temperature in order to assess degradation of the electrochemical cell performance. No significant performance degradation was detected in all studied fuels even pure methane, which suggests that MoNi-Ce is a suitable anode material for direct methane SOFC.

  9. High-capacity nanocarbon anodes for lithium-ion batteries

    International Nuclear Information System (INIS)

    Highlights: • The nanocarbon anodes in lithium-ion batteries deliver a high capacity of ∼1100 mA h g−1. • The nanocarbon anodes exhibit excellent cyclic stability. • A novel structure of carbon materials, hollow carbon nanoboxes, has potential application in lithium-ion batteries. - Abstract: High energy and power density of secondary cells like lithium-ion batteries become much more important in today’s society. However, lithium-ion battery anodes based on graphite material have theoretical capacity of 372 mA h g−1 and low charging-discharging rate. Here, we report that nanocarbons including mesoporous graphene (MPG), carbon tubular nanostructures (CTN), and hollow carbon nanoboxes (HCB) are good candidate for lithium-ion battery anodes. The nanocarbon anodes have high capacity of ∼1100, ∼600, and ∼500 mA h g−1 at 0.1 A g−1 for MPG, CTN, and HCB, respectively. The capacity of 181, 141, and 139 mA h g−1 at 4 A g−1 for MPG, CTN, and HCB anodes is retained. Besides, nanocarbon anodes show high cycling stability during 1000 cycles, indicating formation of a passivating layer—solid electrolyte interphase, which support long-term cycling. Nanocarbons, constructed with graphene layers which fulfill lithiation/delithiation process, high ratio of graphite edge structure, and high surface area which facilitates capacitive behavior, deliver high capacity and improved rate-capability

  10. Nanostructural Engineering of Nanoporous Anodic Alumina for Biosensing Applications

    Directory of Open Access Journals (Sweden)

    Josep Ferré-Borrull

    2014-07-01

    Full Text Available Modifying the diameter of the pores in nanoporous anodic alumina opens new possibilities in the application of this material. In this work, we review the different nanoengineering methods by classifying them into two kinds: in situ and ex situ. Ex situ methods imply the interruption of the anodization process and the addition of intermediate steps, while in situ methods aim at realizing the in-depth pore modulation by continuous changes in the anodization conditions. Ex situ methods permit a greater versatility in the pore geometry, while in situ methods are simpler and adequate for repeated cycles. As an example of ex situ methods, we analyze the effect of changing drastically one of the anodization parameters (anodization voltage, electrolyte composition or concentration. We also introduce in situ methods to obtain distributed Bragg reflectors or rugate filters in nanoporous anodic alumina with cyclic anodization voltage or current. This nanopore engineering permits us to propose new applications in the field of biosensing: using the unique reflectance or photoluminescence properties of the material to obtain photonic barcodes, applying a gold-coated double-layer nanoporous alumina to design a self-referencing protein sensor or giving a proof-of-concept of the refractive index sensing capabilities of nanoporous rugate filters.

  11. Structure of anodized Al-Zr sputter deposited coatings and effect on optical appearance

    Science.gov (United States)

    Gudla, Visweswara Chakravarthy; Canulescu, Stela; Shabadi, Rajashekhara; Rechendorff, Kristian; Dirscherl, Kai; Ambat, Rajan

    2014-10-01

    The mechanism of interaction of light with the microstructure of anodized layer giving specific optical appearance is investigated using Al-Zr sputter deposited coating as a model system on an AA6060 substrate. Differences in the oxidative nature of various microstructural components result in the evolution of typical features in the anodized layer, which are investigated as a function of microstructure and correlated with its optical appearance. The Zr concentration in the coating was varied from 6 wt.% to 23 wt.%. Heat treatment of the coated samples was carried out at 550 °C for 4 h in order to evolve Al-Zr based second phase precipitates in the microstructure. Anodizing was performed using 20 wt.% sulphuric acid at 18 °C with an intention to study the effect of anodizing on the Al-Zr based precipitates in the coating. Detailed microstructural characterization of the coating and anodized layer was carried out using high resolution scanning and transmission electron microscopy, grazing incidence X-ray diffraction analysis, glow discharge optical emission spectroscopy, and optical appearance using spectrophotometry. The evolution of microstructure in the anodized layer as a function of anodizing parameters and their influence on the interaction of light is investigated and the results in general are applicable to discolouration of anodized layer on recycled aluminium alloys due to intermetallics.

  12. Anodic passivation of Pb-Ag-Nd anode in fluoride-containing H2SO4 solution

    Institute of Scientific and Technical Information of China (English)

    钟晓聪; 蒋良兴; 刘芳洋; 李劼; 刘业翔

    2015-01-01

    An attempt was made to build up a thick and compact oxide layer rapidly by pre-treating the Pb-Ag-Nd anode in fluoride-containing H2SO4 solution. The passivation reaction of Pb-Ag-Nd anode during pre-treatment process was investigated using cyclic voltammetry, linear scanning voltammetry, environmental scanning electron microscopy and X-ray diffraction analysis. The results show that PbF2 and PbSO4 are formed near the potential of Pb/PbSO4 couple. The pre-treatment in fluoride-containing H2SO4 solution contributes to the formation of a thick, compact and adherent passive film. Furthermore, pre-treatment in fluoride-containing H2SO4 solution also facilitates the formation of PbO2 on the anodic layer, and the reason could be attributed to the formation of more PbF2 and PbSO4 during the pre-treatment which tend to transform to PbO2 during the following electrowinning process. In addition, the anodic layer on anode with pre-treatment in fluoride-containing H2SO4 solution is thick and compact, and its predominant composition isβ-PbO2. In summary, the pre-treatment in fluoride-containing H2SO4 solution benefits the formation of a desirable protective layer in a short time.

  13. Na-Ion Battery Anodes: Materials and Electrochemistry.

    Science.gov (United States)

    Luo, Wei; Shen, Fei; Bommier, Clement; Zhu, Hongli; Ji, Xiulei; Hu, Liangbing

    2016-02-16

    The intermittent nature of renewable energy sources, such as solar and wind, calls for sustainable electrical energy storage (EES) technologies for stationary applications. Li will be simply too rare for Li-ion batteries (LIBs) to be used for large-scale storage purposes. In contrast, Na-ion batteries (NIBs) are highly promising to meet the demand of grid-level storage because Na is truly earth abundant and ubiquitous around the globe. Furthermore, NIBs share a similar rocking-chair operation mechanism with LIBs, which potentially provides high reversibility and long cycling life. It would be most efficient to transfer knowledge learned on LIBs during the last three decades to the development of NIBs. Following this logic, rapid progress has been made in NIB cathode materials, where layered metal oxides and polyanionic compounds exhibit encouraging results. On the anode side, pure graphite as the standard anode for LIBs can only form NaC64 in NIBs if solvent co-intercalation does not occur due to the unfavorable thermodynamics. In fact, it was the utilization of a carbon anode in LIBs that enabled the commercial successes. Anodes of metal-ion batteries determine key characteristics, such as safety and cycling life; thus, it is indispensable to identify suitable anode materials for NIBs. In this Account, we review recent development on anode materials for NIBs. Due to the limited space, we will mainly discuss carbon-based and alloy-based anodes and highlight progress made in our groups in this field. We first present what is known about the failure mechanism of graphite anode in NIBs. We then go on to discuss studies on hard carbon anodes, alloy-type anodes, and organic anodes. Especially, the multiple functions of natural cellulose that is used as a low-cost carbon precursor for mass production and as a soft substrate for tin anodes are highlighted. The strategies of minimizing the surface area of carbon anodes for improving the first-cycle Coulombic efficiency are

  14. Formation of anodic aluminum oxide with serrated nanochannels.

    Science.gov (United States)

    Li, Dongdong; Zhao, Liang; Jiang, Chuanhai; Lu, Jia G

    2010-08-11

    We report a simple and robust method to self-assemble porous anodic aluminum oxide membranes with serrated nanochannels by anodizing in phosphoric acid solution. Due to high field conduction and anionic incorporation, an increase of anodizing voltage leads to an increase of the impurity levels and also the field strength across barrier layer. On the basis of both experiment and simulation results, the initiation and formation of serrated channels are attributed to the evolution of oxygen gas bubbles followed by plastic deformation in the oxide film. Alternating anodization in oxalic and phosphoric acids is applied to construct multilayered membranes with smooth and serrated channels, demonstrating a unique way to design and construct a three-dimensional hierarchical system with controllable morphology and composition. PMID:20617804

  15. Fundamental degradation mechanisms of layered oxide Li-ion battery cathode materials: Methodology, insights and novel approaches

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Description of recent in operando and in situ analysis methodology. • Surface science approach using photoemission for analysis of cathode surfaces and interfaces. • Ageing and fatigue of layered oxide Li-ion battery cathode materials from the atomistic point of view. • Defect formation and electronic structure evolution as causes for cathode degradation. • Significance of interfacial energy alignment and contact potential for side reactions. - Abstract: This overview addresses the atomistic aspects of degradation of layered LiMO2 (M = Ni, Co, Mn) oxide Li-ion battery cathode materials, aiming to shed light on the fundamental degradation mechanisms especially inside active cathode materials and at their interfaces. It includes recent results obtained by novel in situ/in operando diffraction methods, modelling, and quasi in situ surface science analysis. Degradation of the active cathode material occurs upon overcharge, resulting from a positive potential shift of the anode. Oxygen loss and eventual phase transformation resulting in dead regions are ascribed to changes in electronic structure and defect formation. The anode potential shift results from loss of free lithium due to side reactions occurring at electrode/electrolyte interfaces. Such side reactions are caused by electron transfer, and depend on the electron energy level alignment at the interface. Side reactions at electrode/electrolyte interfaces and capacity fade may be overcome by the use of suitable solid-state electrolytes and Li-containing anodes

  16. Evaluation of the corrosion resistance of anodized aluminum 6061 using electrochemical impedance spectroscopy (EIS)

    Energy Technology Data Exchange (ETDEWEB)

    Huang Yuelong [Corrosion and Environmental Effects Laboratory (CEEL), Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-0241 (United States); Shih Hong [Lam Research Corporation, 4400 Cushing Parkway, Fremont, CA 94538 (United States)], E-mail: hong.shih@lamrc.com; Huang, Huochuan; Daugherty, John; Wu Shun; Ramanathan, Sivakami; Chang, Chris [Lam Research Corporation, 4400 Cushing Parkway, Fremont, CA 94538 (United States); Mansfeld, Florian [Corrosion and Environmental Effects Laboratory (CEEL), Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-0241 (United States)], E-mail: mansfeld@usc.edu

    2008-12-15

    The corrosion resistance of anodized Al 6061 produced by two different anodizing and sealing processes was evaluated using electrochemical impedance spectroscopy (EIS). The scanning electron microscope (SEM) was employed to determine the surface structure and the thickness of the anodized layers. The EIS data revealed that there was very little change of the properties of the anodized layers for samples that were hard anodized in a mixed acid solution and sealed in hot water over a 365 day exposure period in a 3.5 wt% NaCl solution. The specific admittance A{sub s} and the breakpoint frequency f{sub b} remained constant with exposure time confirming that the hard anodizing process used in this study was very effective in providing excellent corrosion resistance of anodized Al 6061 over extended exposure periods. Some minor degradation of the protective properties of the anodized layers was observed for samples that were hard anodized in H{sub 2}SO{sub 4} and exposed to the NaCl solution for 14 days.

  17. Evaluation of the corrosion resistance of anodized aluminum 6061 using electrochemical impedance spectroscopy (EIS)

    International Nuclear Information System (INIS)

    The corrosion resistance of anodized Al 6061 produced by two different anodizing and sealing processes was evaluated using electrochemical impedance spectroscopy (EIS). The scanning electron microscope (SEM) was employed to determine the surface structure and the thickness of the anodized layers. The EIS data revealed that there was very little change of the properties of the anodized layers for samples that were hard anodized in a mixed acid solution and sealed in hot water over a 365 day exposure period in a 3.5 wt% NaCl solution. The specific admittance As and the breakpoint frequency fb remained constant with exposure time confirming that the hard anodizing process used in this study was very effective in providing excellent corrosion resistance of anodized Al 6061 over extended exposure periods. Some minor degradation of the protective properties of the anodized layers was observed for samples that were hard anodized in H2SO4 and exposed to the NaCl solution for 14 days

  18. Corrosion of cermet anodes during low temperature electrolysis of alumina. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kozarek, R.L.; Ray, S.P.; Dawless, R.K.; LaCamera, A.F.

    1997-09-26

    Successful development of inert anodes to replace carbon anodes in Hall cells has the potential benefits of lower energy consumption,lower operating costs, and reduced CO{sub 2} and CO emissions. Using inert anodes at reduced current density and reduced operating temperature (800 C) has potential for decreasing the corrosion rate of inert anodes. It may also permit the use of new materials for containment and insulation. This report describes the fabrication characteristics and the corrosion performance of 5324-17% Cu Cermet anodes in 100 hour tests. Although some good results were achieved, the corrosion rate at low temperature (800 C) is varied and not significantly lower than typical results at high temperature ({approximately} 960 C). This report also describes several attempts at 200 hour tests, with one anode achieving 177 hours of continuous operation and another achieving a total of 235 hours but requiring three separate tests of the same anode. The longest run did show a lower wear rate in the last test; but a high resistance layer developed on the anode surface and forced an unacceptably low current density. It is recommended that intermediate temperatures be explored as a more optimal environment for inert anodes. Other electrolyte chemistries and anode compositions (especially high conductivity anodes) should be considered to alleviate problems associated with lower temperature operation.

  19. Microstructural and electrochemical characterization of Ce conversion layers formed on Al alloy 2024-T3 covered with Cu-rich smut

    International Nuclear Information System (INIS)

    In the present work the microstructure of Ce conversion layers formed on Al alloy 2024-T3 covered with a Cu-rich smut was characterized by scanning electron microscopy (SEM), and its electrochemical behaviour in 0.5 M NaCl solution was investigated by open circuit potential (OCP) measurements, anodic polarization curves and electrochemical impedance spectroscopy (EIS). The results of the microstructural characterization have shown that the presence of Cu cathodic particles uniformly deposited on the electrode surface favours the homogeneous nucleation of the conversion layer, apparently reducing the role of intermetallics in the layer precipitation mechanism. Electrochemical measurements have shown that, during the first hour of immersion in the test electrolyte, the samples covered with the conversion layer exhibit a high interfacial activity, characterized by an active anodic behaviour, which was ascribed to an intense electrochemical activity associated with Al-Cu-Mg intermetallics not covered with the conversion layer. However, as the experiment proceeds an improvement on the corrosion behaviour of the sample was observed, which was interpreted on the basis of self-healing properties of the Ce conversion layer as well as on the blocking of the defective sites of the conversion coating by corrosion products. The electrochemical results have also evidenced the beneficial effect of the pre-treatment with benzotriazole in the corrosion response of Ce-coated samples

  20. Structure of anodized Al–Zr sputter deposited coatings and effect on optical appearance

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Canulescu, Stela; Shabadi, Rajashekhara; Rechendorff, Kristian; Dirscherl, Kai; Ambat, Rajan

    2014-01-01

    The mechanism of interaction of light with the microstructure of anodized layer giving specific optical appearance is investigated using Al–Zr sputter deposited coating as a model system on an AA6060 substrate. Differences in the oxidative nature of various microstructural components result in the...... evolution of typical features in the anodized layer, which are investigated as a function of microstructure and correlated with its optical appearance. The Zr concentration in the coating was varied from 6 wt.% to 23 wt.%. Heat treatment of the coated samples was carried out at 550°C for 4 h in order to...... evolve Al–Zr based second phase precipitates in the microstructure. Anodizing was performed using 20 wt.% sulphuric acidat 18°C with an intention to study the effect of anodizing on the Al–Zr based precipitates in the coating.Detailed microstructural characterization of the coating and anodized layer was...

  1. Interfacial and Electrical Characterization of HfO2 Gate Dielectric Film with a Blocking Layer of Al2O3%具有Al2O3阻挡层的HfO2栅介质膜的界面和电学性能的表征

    Institute of Scientific and Technical Information of China (English)

    程新红; 何大伟; 宋朝瑞; 俞跃辉; 沈达身

    2009-01-01

    研究了经过700℃快速热退火的并在Si界面处插入Al2O3阻挡层的HfO2栅介质膜的界面结构和电学性能.X射线光电子谱表明,退火后,界面层中的siOx转化为化学当量的SiO2,而且未发现铪基硅酸盐和铪基酸化物.由电学测试提取出等效栅氧厚度为2.5nm,固定电荷密度为-4.5×1011/cm2.发现Al2O3阻挡层能有效地阻止Si原子扩散进入HfO2薄膜,进而改善HfO2栅介质膜的界面和电学性能.%HfO2 gate dielectric films with a blocking layer of Al2O3 inserted between HfO2 layer and Si layer (HfO2/Si) were treated with rapid thermal annealing process at 700℃. The interracial structure and electrical properties were reported. The results of X-ray photoelectron spectroscopy showed that the interracial layer of SiOx transformed into SiO2 after the annealing treatment, and Hf-silicates and Hf-silicides were not detected. The results of high-resolution transmission electron microscopy indicated that the in-terracial layer was composed of SiO2 for the annealed film with blocking layer. The results of the electrical measurements indicated that the equivalent oxide thickness decreased to 2.5 nm and the fixed charge density decreased to -4.5×1011/cm2 in comparison with the same thickness of HfO2 films without the blocking layer. Al2O3 layer could effectively prevent the diffusion of Si into HfO2 film and improve the interfacial and electrical performance of HfO2 film.

  2. Surface characteristics of hydroxyapatite films deposited on anodized titanium by an electrochemical method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang [Research Institute, Kuwotech, 970–88, Wolchul-dong, Buk-ku, Gwangju (Korea, Republic of); Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Jeong, Yong-Hoon; Brantley, William A. [Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State, University, Columbus, OH (United States); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of)

    2013-11-01

    The biocompatibility of anodized titanium (Ti) was improved by an electrochemically deposited calcium phosphate (CaP) layer. The CaP layer was grown on the anodized Ti surface in modified simulated body fluid (M-SBF) at 85 °C. The phases and morphologies for the CaP layers were influenced by the electrolyte concentration. Nano flake-like precipitates that formed under low M-SBF concentrations were identified as hydroxyapatite (HAp) crystals orientated in the c-axis direction. In high M-SBF concentrations, the CaP layer formed micro plate-like precipitates on anodized Ti, and micropores were covered with HAp. Proliferation of murine preosteoblast cell (MC3T3-E1) on the HAp/anodized Ti surfaces was significantly higher than for untreated Ti and anodized Ti surfaces. - Highlights: • CaP layers were grown on anodized Ti surfaces by an electrochemical deposition process. • Phases and morphologies of layers were influenced by the electrolyte concentration. • Superior cell proliferation was observed on hydroxyapatite-coated anodized surfaces.

  3. Surface characteristics of hydroxyapatite films deposited on anodized titanium by an electrochemical method

    International Nuclear Information System (INIS)

    The biocompatibility of anodized titanium (Ti) was improved by an electrochemically deposited calcium phosphate (CaP) layer. The CaP layer was grown on the anodized Ti surface in modified simulated body fluid (M-SBF) at 85 °C. The phases and morphologies for the CaP layers were influenced by the electrolyte concentration. Nano flake-like precipitates that formed under low M-SBF concentrations were identified as hydroxyapatite (HAp) crystals orientated in the c-axis direction. In high M-SBF concentrations, the CaP layer formed micro plate-like precipitates on anodized Ti, and micropores were covered with HAp. Proliferation of murine preosteoblast cell (MC3T3-E1) on the HAp/anodized Ti surfaces was significantly higher than for untreated Ti and anodized Ti surfaces. - Highlights: • CaP layers were grown on anodized Ti surfaces by an electrochemical deposition process. • Phases and morphologies of layers were influenced by the electrolyte concentration. • Superior cell proliferation was observed on hydroxyapatite-coated anodized surfaces

  4. Scaling of interfacial jump conditions

    International Nuclear Information System (INIS)

    To model the behavior of a nuclear reactor accurately is needed to have balance models that take into account the different phenomena occurring in the reactor. These balances have to be coupled together through boundary conditions. The boundary conditions have been studied and different treatments have been given to the interface. In this paper is a brief description of some of the interfacial jump conditions that have been proposed in recent years. Also, the scaling of an interfacial jump condition is proposed, for coupling the different materials that are in contact within a nuclear reactor. (Author)

  5. The effect of the carbon nanotube buffer layer on the performance of a Li metal battery

    Science.gov (United States)

    Zhang, Ding; Zhou, Yi; Liu, Changhong; Fan, Shoushan

    2016-05-01

    Lithium (Li) metal is one of the most promising candidates as an anode for the next-generation energy storage systems because of its high specific capacity and lowest negative electrochemical potential. But the growth of Li dendrites limits the application of the Li metal battery. In this work, a type of modified Li metal battery with a carbon nanotube (CNT) buffer layer inserted between the separator and the Li metal electrode was reported. The electrochemical results show that the modified batteries have a much better rate capability and cycling performance than the conventional Li metal batteries. The mechanism study by electrochemical impedance spectroscopy reveals that the modified battery has a smaller charge transfer resistance and larger Li ion diffusion coefficient during the deposition process on the Li electrode than the conventional Li metal batteries. Symmetric battery tests show that the interfacial behavior of the Li metal electrode with the buffer layer is more stable than the naked Li metal electrode. The morphological characterization of the CNT buffer layer and Li metal lamina reveals that the CNT buffer layer has restrained the growth of Li dendrites. The CNT buffer layer has great potential to solve the safety problem of the Li metal battery.Lithium (Li) metal is one of the most promising candidates as an anode for the next-generation energy storage systems because of its high specific capacity and lowest negative electrochemical potential. But the growth of Li dendrites limits the application of the Li metal battery. In this work, a type of modified Li metal battery with a carbon nanotube (CNT) buffer layer inserted between the separator and the Li metal electrode was reported. The electrochemical results show that the modified batteries have a much better rate capability and cycling performance than the conventional Li metal batteries. The mechanism study by electrochemical impedance spectroscopy reveals that the modified battery has a

  6. Synergistic effect of amorphous carbon coverage and enlarged voltage window on the superior lithium storage performance of nanostructured mesoporous anatase TiO2: Emphasis on interfacial storage phenomena

    International Nuclear Information System (INIS)

    Highlights: • Interconnected agglomerates of nanoparticles are assembled into a porous network. • Both bulk insertion and interfacial storage contribute to the high capacity. • The enlarged voltage window of 0.01–3.0 V is employed firstly. • An ultrathin carbon layer (1 nm thick) helps to avoid the structure instability. • The obtained nanoparticles have a high capacity of 270 mA h g−1 at 300th cycle. - Abstract: Mesoporous anatase TiO2 nanoparticles coated with an ultrathin layer of amorphous carbon are hydrothermally synthesized. Used as an anode material, it achieves a sustained superior lithium storage performance, presenting a high reversible capacity of 270 mA h g−1 up to 300 cycles at a current density of 30 mA h g−1 in an enlarged voltage window of 0.01–3 V, which is firstly adopted for TiO2 anode material. Remarkably, the carbon coated TiO2 nanoparticles can still maintain a capacity of 171 mA h g−1 at 300 mA g−1 after 1000 cycles, and even 93 mA h g−1 at 600 mA g−1 after 1000 cycles. We propose an overall view on the diverse features influencing the electrochemical performance of the high-surface-area mesoporous carbon coated TiO2 nanoparticles and emphasize that the excellent performance is the synergistic result of the enlarged voltage window, which leads to higher interfacial lithium storage, and the uniform amorphous carbon coverage, which not only improves electrical conductivity, minimizes the direct solid-electrolyte interphase (SEI) formation, but also helps to avoid the structure instability arising from the enlargement of the potential window

  7. Full Ceramic Fuel Cells Based on Strontium Titanate Anodes, An Approach Towards More Robust SOFCs

    DEFF Research Database (Denmark)

    Holtappels, Peter; Irvine, J.T.S.; Iwanschitz, B.;

    2013-01-01

    intact and tolerant to redox cycles, cell performance degradation appears linked to the infiltrated electro catalysts. The materials have also been assessed with respect to their electrical and mechanical properties, in order to further evaluate their potential use as anode and anode support layers in...

  8. Photoelectrochemical cell with nondissolving anode

    Science.gov (United States)

    Ellis, A. B.; Kaiser, S. W.; Wrighton, M. S.

    1980-01-01

    Improved electrolytic cells have efficiencies comparable to those of best silicon solar cells but are potentially less expensive to manufacture. Cells consist of light-sensitive n-type semiconductor anode and metallic cathode immersed in electrolytic solution. Reversible redox cells produce no chemical change in electrolyte and stabilize anode against dissolving. Cell can produce more than 500 mW of power per square centimeter of anode area at output voltage of 0.4 V.

  9. Role of the elasticity of pharmaceutical materials on the interfacial mechanical strength of bilayer tablets.

    Science.gov (United States)

    Busignies, Virginie; Mazel, Vincent; Diarra, Harona; Tchoreloff, Pierre

    2013-11-30

    The effect of the elasticity of various pharmaceutical materials on the interfacial adhesion in bilayer tablets was investigated. The elastic properties of five pharmaceutical products were characterized by their total elastic recovery. To test the interfacial strength of the bilayer tablets a new flexural test was proposed. Thanks to the test configuration, the experimental breaking force is directly correlated with the interfacial layer strength. Depending on the materials, the fracture occurred over the interface or in one of the two layers. In most cases, the highest breaking forces were obtained when the materials had close elastic recovery. On the contrary, for materials with different elastic recovery, the breaking forces were reduced. The observed changes in the interfacial mechanical strength were statistically analyzed. Such an approach has an importance in the growing interest in the Quality by Design (QbD) concept in pharmaceutical industry. PMID:24055440

  10. Fabrication of alumina films with laminated structures by ac anodization

    International Nuclear Information System (INIS)

    Anodization techniques by alternating current (ac) are introduced in this review. By using ac anodization, laminated alumina films are fabricated. Different types of alumina films consisting of 50–200 nm layers were obtained by varying both the ac power supply and the electrolyte. The total film thickness increased with an increase in the total charge transferred. The thickness of the individual layers increased with the ac voltage; however, the anodization time had little effect on the film thickness. The laminated alumina films resembled the nacre structure of shells, and the different morphologies exhibited by bivalves and spiral shells could be replicated by controlling the rate of increase of the applied potentials. (paper)

  11. The effect of capillary pressure for concave liquid-vapor interface on interfacial evaporation

    Institute of Scientific and Technical Information of China (English)

    张金涛; 王补宣; 彭晓峰

    2001-01-01

    The analysis in this paper demonstrates that the capillary pressure on the concave liquid-vapor interface will promote the interfacial evaporation, therefore clarifying the confusion over the great difference between the estimated and real rate of interfacial evaporation. This difference increases with decreasing capillary radius, and becomes more apparent for liquid with high latent heat. The present analysis also shows that the capillary pressure on the concave interface will result in a decrease in liquid phase equilibrium temperature, which can explain the possibility of vapor bubble formation on micro liquid layer interfacial evaporation under low superheat, or even below the nominal saturated temperature.

  12. Enhanced H2/CH4 and H2/CO2 Separation by Carbon Molecular Sieve Membrane Coated on Titania Modified Alumina Support: Effects of TiO2 Intermediate Layer Preparation Variables on Interfacial Adhesion.

    Czech Academy of Sciences Publication Activity Database

    Tseng, H.-H.; Wang, Ch.-T.; Zhuang, G.-L.; Uchytil, Petr; Řezníčková Čermáková, Jiřina; Setničková, Kateřina

    2016-01-01

    Roč. 510, JUL 15 (2016), s. 391-404. ISSN 0376-7388 Grant ostatní: NSC(TW) NSC100-2221-E- 040-004-MY3 Institutional support: RVO:67985858 Keywords : carbon membrane * intermediate layer * adhesion Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 5.056, year: 2014

  13. Fabrication of complete titania nanoporous structures via electrochemical anodization of Ti

    OpenAIRE

    Ali Ghafar; Chen Chong; Yoo Seung; Kum Jong; Cho Sung

    2011-01-01

    Abstract We present a novel method to fabricate complete and highly oriented anodic titanium oxide (ATO) nano-porous structures with uniform and parallel nanochannels. ATO nano-porous structures are fabricated by anodizing a Ti-foil in two different organic viscous electrolytes at room temperature using a two-step anodizing method. TiO2 nanotubes covered with a few nanometer thin nano-porous layer is produced when the first and the second anodization are carried out in the same electrolyte. H...

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

    Science.gov (United States)

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

    2016-02-01

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

  15. Limiting amplitudes of fully nonlinear interfacial tides and solitons

    OpenAIRE

    Aguiar-González, Borja; Gerkema, Theo

    2016-01-01

    A new two-fluid layer model consisting of forced rotation-modified Boussinesq equations is derived for studying tidally-generated fully nonlinear, weakly nonhydrostatic dispersive interfacial waves. This set is a generalization of the Choi-Camassa equations, extended here with forcing terms and Coriolis effects. The forcing is represented by a horizontally oscillating sill, mimicking a barotropic tidal flow over topography. Solitons are generated by a disintegration...

  16. An Aggregation-Induced-Emission Platform for Direct Visualization of Interfacial Dynamic Self-Assembly**

    OpenAIRE

    Li, Junwei; Li, Yuan; Chan, Carrie Y.K.; Ryan T. K. Kwok; Li, Hongkun; Zrazhevskiy, Pavel; Gao, Xiaohu; Sun, Jing Zhi; Qin, Anjun; Tang, Ben Zhong

    2014-01-01

    An in-depth understanding of dynamic interfacial self-assembly processes is essential for a wide range of topics in theoretical physics, materials design, and biomedical research. However, direct monitoring of such processes is hampered by the poor imaging contrast of a thin interfacial layer. We report in situ imaging technology capable of selectively highlighting self-assembly at the phase boundary in real time by employing the unique photophysical properties of aggregation-induced emission...

  17. The effect of interfacial intermixing on magnetization and anomalous Hall effect in Co/Pd multilayers

    KAUST Repository

    Guo, Zaibing

    2015-05-01

    The effect of interfacial intermixing on magnetization and anomalous Hall effect (AHE) in Co/Pd multilayers is studied by using rapid thermal annealing to enhance the interfacial diffusion. The dependence of saturation magnetization and coercivity on the temperature of rapid thermal annealing at 5 K is discussed. It is found that AHE is closely related to the relative thickness of the Co and Pd layers. Localized paramagnetism has been observed which destroys AHE, while AHE can be enhanced by annealing.

  18. Electrode Polarization in Glassy Electrolytes: Large Interfacial Capacitance Values and Indication for Pseudocapacitive Charge Storage

    OpenAIRE

    Mariappan, C. R.; Heins, T. P.; Roling, B.

    2009-01-01

    We study the electrode polarization behaviour of different Na-Ca-phosphosilicate glasses by measuring the differential capacitance between blocking Pt electrodes. At low applied dc bias voltages, we detect a linear capacitance regime with interfacial capacitance values considerably larger than expected from double layer theories and also considerably larger than found for ionic liquids with similar ion concentrations. With increasing bias voltages, the differential capacitance of interfacial ...

  19. On the mechanisms of cation injection in conducting bridge memories: The case of HfO2 in contact with noble metal anodes (Au, Cu, Ag)

    Science.gov (United States)

    Saadi, M.; Gonon, P.; Vallée, C.; Mannequin, C.; Grampeix, H.; Jalaguier, E.; Jomni, F.; Bsiesy, A.

    2016-03-01

    Resistance switching is studied in HfO2 as a function of the anode metal (Au, Cu, and Ag) in view of its application to resistive memories (resistive random access memories, RRAM). Current-voltage (I-V) and current-time (I-t) characteristics are presented. For Au anodes, resistance transition is controlled by oxygen vacancies (oxygen-based resistive random access memory, OxRRAM). For Ag anodes, resistance switching is governed by cation injection (Conducting Bridge random access memory, CBRAM). Cu anodes lead to an intermediate case. I-t experiments are shown to be a valuable tool to distinguish between OxRRAM and CBRAM behaviors. A model is proposed to explain the high-to-low resistance transition in CBRAMs. The model is based on the theory of low-temperature oxidation of metals (Cabrera-Mott theory). Upon electron injection, oxygen vacancies and oxygen ions are generated in the oxide. Oxygen ions are drifted to the anode, and an interfacial oxide is formed at the HfO2/anode interface. If oxygen ion mobility is low in the interfacial oxide, a negative space charge builds-up at the HfO2/oxide interface. This negative space charge is the source of a strong electric field across the interfacial oxide thickness, which pulls out cations from the anode (CBRAM case). Inversely, if oxygen ions migration through the interfacial oxide is important (or if the anode does not oxidize such as Au), bulk oxygen vacancies govern resistance transition (OxRRAM case).

  20. Three-layer model for exchange anisotropy

    Science.gov (United States)

    Rezende, S. M.; Azevedo, A.; de Aguiar, F. M.; Fermin, J. R.; Egelhoff, W. F.; Parkin, S. S.

    2002-08-01

    Recent x-ray absorption measurements have indicated that the interface between the antiferromagnetic (AF) and the ferromagnetic (FM) layers in AF/FM bilayers instead of being abrupt, consists of a thin layer with uncompensated spins. Here the effect of an interfacial layer between the AF and FM layers on the ferromagnetic resonance response is investigated using a three-layer model for the exchange anisotropy. The calculated dependence of the resonance field with the azimuthal angle of the in-plane external field agrees quite well with experimental data in several samples, lending support to the existence of the uncompensated interfacial layer.

  1. Influence of Fluoride Ion on the Performance of Pb-Ag Anode During Long-Term Galvanostatic Electrolysis

    Science.gov (United States)

    Zhong, Xiaocong; Yu, Xiaoying; Jiang, Liangxing; Lv, Xiaojun; Liu, Fangyang; Lai, Yanqing; Li, Jie

    2015-09-01

    Anodic potential, morphology and phase composition of the anodic layer, corrosion morphology of the metallic substrate, and oxygen evolution behavior of Pb-Ag anode in H2SO4 solution without/with fluoride ion were investigated and compared. The results showed that the presence of fluoride ions contributed to a smoother anodic layer with lower PbO2 concentration, which resulted in lower double layer capacity and higher charge transfer resistance for the oxygen evolution reaction. Consequently, the Pb-Ag anode showed a higher anodic potential (about 35 mV) in the fluoride-containing electrolyte. In addition, the fluoride ions accelerated the detachment of loose flakes on the anodic layer. It was demonstrated that the anodic layer formed in the fluoride-containing H2SO4 solution was thinner. Furthermore, fluoride ions aggravated the corrosion of the metallic substrate at interdendritic boundary regions. Hence, the presence of fluoride ions is detrimental to oxygen evolution reactivity and increases the corrosion of the Pb-Ag anode, which may further increase the energy consumption and capital cost of zinc plants.

  2. STUDY ON COMPOSITION IN NIOBIUM ANODE

    Institute of Scientific and Technical Information of China (English)

    Li Chunguang; Gao Yong; Dong Ningli

    2004-01-01

    Niobium capacitor uses electrolytic Nb2O5 as dielectric layer formed on surface of porous niobium anode through electrolytic reaction. Analysis of Scanning Electronics Microscope (SEM) combined with X-ray Photoemission Spectrum(XPS) shows that the formed niobium oxide dielectric consists of not only Nb2O5, but also two kinds of low valence niobium NbO2 and NbO oxide. When using different electrolytic reaction conditions, different valence niobium oxide shows different relative content. The fact provides an important basis for analyzing and improving performances of niobium capacitor.

  3. An Analysis of Mechanical Properties of Anodized Aluminum Film at High Stress

    Science.gov (United States)

    Zhao, Xixi; Wei, Guoying; Yu, Yundan; Guo, Yuemei; Zhang, Ao

    2015-10-01

    In this paper, a new environmental-friendly electrolyte containing sulfuric acid and tartaric acid has been used as the substitute of chromic acid for anodization. The work discussed the influence of anodizing voltages on the fatigue life of anodized Al 2024-T3 by performing fatigue tests with 0.1 stress ratio (R) at 320 MPa. Meanwhile the fatigue cycles to failure, yield strength, tensile strength and fracture surface of anodic films at different conditions were investigated. The results showed that the fatigue life of anodized and sealed specimens reduced a lot compared to aluminum alloy, which can be attributed to the crack sites initiated at the oxide layer. The fracture surface analyses also revealed that the number of crack initiation sites enlarged with the increase of anodizing voltage.

  4. Exciton quenching at PEDOT:PSS anode in polymer blue-light-emitting diodes

    International Nuclear Information System (INIS)

    The quenching of excitons at the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) anode in blue polyalkoxyspirobifluorene-arylamine polymer light-emitting diodes is investigated. Due to the combination of a higher electron mobility and the presence of electron traps, the recombination zone shifts from the cathode to the anode with increasing voltage. The exciton quenching at the anode at higher voltages leads to an efficiency roll-off. The voltage dependence of the luminous efficiency is reproduced by a drift-diffusion model under the condition that quenching of excitons at the PEDOT:PSS anode and metallic cathode is of equal strength. Experimentally, the efficiency roll-off at high voltages due to anode quenching is eliminated by the use of an electron-blocking layer between the anode and the light-emitting polymer

  5. Exciton quenching at PEDOT:PSS anode in polymer blue-light-emitting diodes

    Science.gov (United States)

    Abbaszadeh, D.; Wetzelaer, G. A. H.; Nicolai, H. T.; Blom, P. W. M.

    2014-12-01

    The quenching of excitons at the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) anode in blue polyalkoxyspirobifluorene-arylamine polymer light-emitting diodes is investigated. Due to the combination of a higher electron mobility and the presence of electron traps, the recombination zone shifts from the cathode to the anode with increasing voltage. The exciton quenching at the anode at higher voltages leads to an efficiency roll-off. The voltage dependence of the luminous efficiency is reproduced by a drift-diffusion model under the condition that quenching of excitons at the PEDOT:PSS anode and metallic cathode is of equal strength. Experimentally, the efficiency roll-off at high voltages due to anode quenching is eliminated by the use of an electron-blocking layer between the anode and the light-emitting polymer.

  6. Exciton quenching at PEDOT:PSS anode in polymer blue-light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Abbaszadeh, D.; Wetzelaer, G. A. H. [Molecular Electronics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen (Netherlands); Dutch Polymer Institute, P.O. Box 902, 5600 AX, Eindhoven (Netherlands); Nicolai, H. T. [TNO/Holst Centre, High Tech Campus 31, 5605 KN, Eindhoven (Netherlands); Blom, P. W. M., E-mail: blom@mpip-mainz.mpg.de [Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany); Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia)

    2014-12-14

    The quenching of excitons at the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) anode in blue polyalkoxyspirobifluorene-arylamine polymer light-emitting diodes is investigated. Due to the combination of a higher electron mobility and the presence of electron traps, the recombination zone shifts from the cathode to the anode with increasing voltage. The exciton quenching at the anode at higher voltages leads to an efficiency roll-off. The voltage dependence of the luminous efficiency is reproduced by a drift-diffusion model under the condition that quenching of excitons at the PEDOT:PSS anode and metallic cathode is of equal strength. Experimentally, the efficiency roll-off at high voltages due to anode quenching is eliminated by the use of an electron-blocking layer between the anode and the light-emitting polymer.

  7. Features of the formation of anodic niobium oxide in a potassium nitrate melt

    Energy Technology Data Exchange (ETDEWEB)

    Skatkov, L.I.; Malyuk, Yu.I.

    1988-07-10

    This work is a further development of the investigations of the processes of the anodization of niobium in nitrate melts of salts at temperatures allowing recrystallization of the oxide. The anodic films of niobium formed in a nitrate melt consist of sandwiches of phases of Nb/sub 2/O/sub 5/, NbO/sub 2/, and NbO (from the outer surface of the anodic oxide film toward the niobium substrate), and high anodization temperatures cause the intense dissolution of oxygen in the niobium substrate. During the formation of an anodic oxide film, it becomes saturated with the anionic and cationic components of the electrolyte. The uptake of the anions is most significant in the initial stages of growth of the oxide layer, while saturation with potassium occurs in the final stages of anodization.

  8. Dead Waters: Large amplitude interfacial waves generated by a boat in a stratified fluid

    CERN Document Server

    Vasseur, Romain; Dauxois, Thierry

    2008-01-01

    We present fluid dynamics videos of the motion of a boat on a two-layer or three-layer fluid. Under certain specific conditions, this setup generates large amplitude interfacial waves, while no surface waves are visible. The boat is slowed down leading to a peristaltic effect and sometimes even stopped: this is the so-called dead water phenomenon.

  9. Modeling of the anode surface deformation in high-current vacuum arcs with AMF contacts

    Science.gov (United States)

    Huang, Xiaolong; Wang, Lijun; Deng, Jie; Jia, Shenli; Qin, Kang; Shi, Zongqian

    2016-02-01

    azimuthal velocity of the anode melting pool for arc current 12.5 kA root-mean-square (rms) is larger than that for 17.5 kA (rms), which is likely to be caused by the thinner liquid layer, and also a smaller melting pool mass of 12.5 kA.

  10. Modeling of the anode surface deformation in high-current vacuum arcs with AMF contacts

    International Nuclear Information System (INIS)

    azimuthal velocity of the anode melting pool for arc current 12.5 kA root-mean-square (rms) is larger than that for 17.5 kA (rms), which is likely to be caused by the thinner liquid layer, and also a smaller melting pool mass of 12.5 kA. (paper)

  11. Screened Anode N2 Laser

    OpenAIRE

    Sabry, M. Montaser Foad

    1985-01-01

    An experimental study of the effect of screening the discharge channel on the output energy is presented. It has been found that a screened anode nitrogen laser generates higher output energy than that of a screened cathode, and also higher than that when both cathode and anode are unshielded at higher pressures.

  12. Mesoporous Silicon-Based Anodes

    Science.gov (United States)

    Peramunage, Dharmasena

    2015-01-01

    For high-capacity, high-performance lithium-ion batteries. A new high-capacity anode composite based on mesoporous silicon is being developed. With a structure that resembles a pseudo one-dimensional phase, the active anode material will accommodate significant volume changes expected upon alloying and dealloying with lithium (Li).

  13. Bioactivity of zirconia nanotube arrays fabricated by electrochemical anodization

    International Nuclear Information System (INIS)

    Zirconia nanotubes with a diameter of 50 nm and a length of 20 μm were fabricated by anodic oxidation of zirconium in (NH4)2SO4 electrolyte containing NH4F. The structure and phase composition of the zirconia nanotube layers were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The bioactivity was assessed by investigating the formation of apatite on the surface of zirconia nanotubes after soaking in simulated body fluids (SBF) for 20-30 days. The results indicate that bone-like apatite can be formed on the surface of the zirconia nanotube layers in our SBF immersion experiments. Microstructure of zirconia nanotubes with apatite layer was observed by SEM. Substance and phase compositions were characterized respectively by energy dispersive X-ray spectrometer (EDS) and XRD. Our results show that zirconia nanotube layers fabricated by electrochemical anodization exhibit favorable bioactivity.

  14. Liquid metal actuation by electrical control of interfacial tension

    Science.gov (United States)

    Eaker, Collin B.; Dickey, Michael D.

    2016-09-01

    By combining metallic electrical conductivity with low viscosity, liquid metals and liquid metal alloys offer new and exciting opportunities to serve as reconfigurable components of electronic, microfluidic, and electromagnetic devices. Here, we review the physics and applications of techniques that utilize voltage to manipulate the interfacial tension of liquid metals; such techniques include electrocapillarity, continuous electrowetting, electrowetting-on-dielectric, and electrochemistry. These techniques lower the interfacial tension between liquid metals and a surrounding electrolyte by driving charged species (or in the case of electrochemistry, chemical species) to the interface. The techniques are useful for manipulating and actuating liquid metals at sub-mm length scales where interfacial forces dominate. We focus on metals and alloys that are liquid near or below room temperature (mercury, gallium, and gallium-based alloys). The review includes discussion of mercury—despite its toxicity—because it has been utilized in numerous applications and it offers a way of introducing several phenomena without the complications associated with the oxide layer that forms on gallium and its alloys. The review focuses on the advantages, applications, opportunities, challenges, and limitations of utilizing voltage to control interfacial tension as a method to manipulate liquid metals.

  15. Carbonaceous deposits in direct utilization hydrocarbon SOFC anode

    Science.gov (United States)

    He, Hongpeng; Vohs, John M.; Gorte, Raymond J.

    Carbonaceous deposits formed in Cu-based SOFC anode compartment by exposing porous YSZ anodes to n-butane at elevated temperatures were studied using a combination of V- I curves, impedance spectroscopy, SEM, and TPO measurements. While short-term exposure of a porous YSZ matrix to n-butane at 973 K resulted in the deposition of electronically conducting carbonaceous film and therefore to enhance the fuel cell performance, the power density decays quickly in n-butane at temperature 1073 K or higher for long-term operation. SEM results indicate that the carbonaceous deposits arising from gas phase reaction have different morphology, and a dense layer composed of poly-aromatic rings has been formed on the porous anode surface. The dense layer could block the penetration of fuels to the anode and ions transfer to the three-phase boundaries where electrochemical reactions occur, resulting in the drop of the power density. TPO measurements revealed that the amount of carbonaceous deposits increased and the type of deposits changed with exposure time to n-butane. The stability of deposits increased with extending the exposure time according to the increased oxidation temperature. Steam can remove the carbonaceous deposits from the porous YSZ anode, but the reaction temperature was severely elevated compared to that of oxygen. The carbonaceous deposits can also be removed at 973 K by steam but the deposition of carbon will be controlled by the speed of removal and formation from the gas phase reaction.

  16. Iridium Interfacial Stack - IrIS

    Science.gov (United States)

    Spry, David

    2012-01-01

    Iridium Interfacial Stack (IrIS) is the sputter deposition of high-purity tantalum silicide (TaSi2-400 nm)/platinum (Pt-200 nm)/iridium (Ir-200 nm)/platinum (Pt-200 nm) in an ultra-high vacuum system followed by a 600 C anneal in nitrogen for 30 minutes. IrIS simultaneously acts as both a bond metal and a diffusion barrier. This bondable metallization that also acts as a diffusion barrier can prevent oxygen from air and gold from the wire-bond from infiltrating silicon carbide (SiC) monolithically integrated circuits (ICs) operating above 500 C in air for over 1,000 hours. This TaSi2/Pt/Ir/Pt metallization is easily bonded for electrical connection to off-chip circuitry and does not require extra anneals or masking steps. There are two ways that IrIS can be used in SiC ICs for applications above 500 C: it can be put directly on a SiC ohmic contact metal, such as Ti, or be used as a bond metal residing on top of an interconnect metal. For simplicity, only the use as a bond metal is discussed. The layer thickness ratio of TaSi2 to the first Pt layer deposited thereon should be 2:1. This will allow Si from the TaSi2 to react with the Pt to form Pt2Si during the 600 C anneal carried out after all layers have been deposited. The Ir layer does not readily form a silicide at 600 C, and thereby prevents the Si from migrating into the top-most Pt layer during future anneals and high-temperature IC operation. The second (i.e., top-most) deposited Pt layer needs to be about 200 nm to enable easy wire bonding. The thickness of 200 nm for Ir was chosen for initial experiments; further optimization of the Ir layer thickness may be possible via further experimentation. Ir itself is not easily wire-bonded because of its hardness and much higher melting point than Pt. Below the iridium layer, the TaSi2 and Pt react and form desired Pt2Si during the post-deposition anneal while above the iridium layer remains pure Pt as desired to facilitate easy and strong wire-bonding to the Si

  17. Infiltrated SrTiO3:FeCr-based anodes for metalsupported SOFC

    DEFF Research Database (Denmark)

    Blennow Tullmar, Peter; Persson, Åsa Helen; Nielsen, Jimmi;

    2012-01-01

    ) and FeCr. Electrochemical characterization and post test SEM analysis have been used to get an insight into the possible degradation mechanisms of this novel electrode infiltrated with Gd-doped CeO2 and Ni. Accelerated oxidation/corrosion experiments have been conducted to evaluate the microstructural...... changes occurring in the anode layer during testing. The results indicate that the STN component in the anode seems to have a positive effect on the corrosion stability of the FeCr-particles in the anode layer....

  18. Infiltrated SrTiO3:FeCr-based anodes for metalsupported SOFC

    DEFF Research Database (Denmark)

    Blennow Tullmar, Peter; Persson, Åsa Helen; Nielsen, Jimmi;

    ) and FeCr. Electrochemical characterization and post test SEM analysis have been used to get an insight into the possible degradation mechanisms of this novel electrode infiltrated with Gd-doped CeO2 and Ni. Accelerated oxidation/corrosion experiments have been conducted to evaluate the microstructural...... changes occurring in the anode layer during testing. The results indicate that the STN component in the anode seems to have a positive effect on the corrosion stability of the FeCr-particles in the anode layer....

  19. Elastocapillary-mediated interfacial assembly

    Science.gov (United States)

    Evans, Arthur

    2015-11-01

    Particles confined to an interface are present in a large number of industrial applications and ubiquitous in cellular biophysics. Interactions mediated by the interface, such as capillary effects in the presence of surface tension, give rise to rafts and aggregates whose structure is ultimately determined by geometric characteristics of these adsorbed particles. A common strategy for assembling interfacial structures relies on exploiting these interactions by tuning particle anisotropy, either by constructing rigid particles with heterogeneous wetting properties or fabricating particles that have a naturally anisotropic shape. Less explored, however, is the scenario where the interface causes the particles to deform. In this talk I will discuss the implications for interfacial assembly using elastocapillary-mediated interactions. The competition between surface energy and elasticity can wrinkle and buckle adsorbed soft particles, leading to complicated (but programmable) aggregates.

  20. Mechanics of Interfacial Composite Materials

    OpenAIRE

    Subramaniam, Anand Bala; Abkarian, Manouk; Mahadevan, L.; Stone, Howard A.

    2006-01-01

    Recent experiments and simulations have demonstrated that particle-covered interfaces can exist in stable non-spherical shapes as a result of the steric jamming of the interfacially trapped particles, which confers the interface with solid-like properties. We provide an experimental and theoretical characterization of the mechanical properties of these armored objects, with attention given to the two-dimensional granular state of the interface. Small inhomogeneous stresses produce a plastic r...