WorldWideScience

Sample records for amorphous mixed oxides

  1. Amorphous mixed-metal hydroxide nanostructures for advanced water oxidation catalysts

    Science.gov (United States)

    Gao, Y. Q.; Liu, X. Y.; Yang, G. W.

    2016-02-01

    The design of highly efficient, durable, and earth-abundant catalysts for the oxygen evolution reaction (OER) is crucial in order to promote energy conversion and storage processes. Here, we synthesize amorphous mixed-metal (Ni-Fe) hydroxide nanostructures with a homogeneous distribution of Ni/Fe as well as a tunable Ni/Fe ratio by a simple, facile, green and low-cost electrochemical technique, and we demonstrate that the synthesized amorphous nanomaterials possess ultrahigh activity and super long-term cycle stability in the OER process. The amorphous Ni0.71Fe0.29(OH)x nanostructure affords a current density of 10 mA cm-2 at an overpotential of a mere 0.296 V and a small Tafel slope of 58 mV dec-1, while no deactivation is detected in the CV testing even up to 30 000 cycles, which suggests the promising application of these amorphous nanomaterials in electrochemical oxidation. Meanwhile, the distinct catalytic activities among these amorphous Ni-Fe hydroxide nanostructures prompts us to take notice of the composition of the alloy hydroxides/oxides when studying their catalytic properties, which opens an avenue for the rational design and controllable preparation of such amorphous nanomaterials as advanced OER electrocatalysts.The design of highly efficient, durable, and earth-abundant catalysts for the oxygen evolution reaction (OER) is crucial in order to promote energy conversion and storage processes. Here, we synthesize amorphous mixed-metal (Ni-Fe) hydroxide nanostructures with a homogeneous distribution of Ni/Fe as well as a tunable Ni/Fe ratio by a simple, facile, green and low-cost electrochemical technique, and we demonstrate that the synthesized amorphous nanomaterials possess ultrahigh activity and super long-term cycle stability in the OER process. The amorphous Ni0.71Fe0.29(OH)x nanostructure affords a current density of 10 mA cm-2 at an overpotential of a mere 0.296 V and a small Tafel slope of 58 mV dec-1, while no deactivation is detected in the CV

  2. Amorphous mixed-metal hydroxide nanostructures for advanced water oxidation catalysts.

    Science.gov (United States)

    Gao, Y Q; Liu, X Y; Yang, G W

    2016-03-01

    The design of highly efficient, durable, and earth-abundant catalysts for the oxygen evolution reaction (OER) is crucial in order to promote energy conversion and storage processes. Here, we synthesize amorphous mixed-metal (Ni-Fe) hydroxide nanostructures with a homogeneous distribution of Ni/Fe as well as a tunable Ni/Fe ratio by a simple, facile, green and low-cost electrochemical technique, and we demonstrate that the synthesized amorphous nanomaterials possess ultrahigh activity and super long-term cycle stability in the OER process. The amorphous Ni0.71Fe0.29(OH)x nanostructure affords a current density of 10 mA cm(-2) at an overpotential of a mere 0.296 V and a small Tafel slope of 58 mV dec(-1), while no deactivation is detected in the CV testing even up to 30 000 cycles, which suggests the promising application of these amorphous nanomaterials in electrochemical oxidation. Meanwhile, the distinct catalytic activities among these amorphous Ni-Fe hydroxide nanostructures prompts us to take notice of the composition of the alloy hydroxides/oxides when studying their catalytic properties, which opens an avenue for the rational design and controllable preparation of such amorphous nanomaterials as advanced OER electrocatalysts. PMID:26864279

  3. Selective oxidations on vanadiumoxide containing amorphous mixed oxides (AMM-V) with tert.-butylhydroperoxide

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Y.; Hunnius, M.; Storck, S.; Maier, W.F. [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany)

    1998-12-31

    The catalytic oxygen transfer properties of vanadium containing zeolites and vanadium based sol-gel catalysts with hydrogen peroxides are well known. The severe problem of vanadium leaching caused by the presence of the by-product water has been addressed. To avoid any interference with homogeneously catalyzed reactions, our study focusses on selective oxidations in a moisture-free medium with tert.-butylhydroperoxide. We have investigated the catalytic properties of amorphous microporous materials based on SiO{sub 2}, TiO{sub 2}, ZrO{sub 2} and Al{sub 2}O{sub 3} as matrix material and studied the effects of surface polarity on the oxidation of 1-octene and cyclohexane. (orig.)

  4. Selective oxidation of benzene and cyclohexane using amorphous microporous mixed oxides; Selektive Oxidation von Benzol und Cyclohexan mit amorphen mikroporoesen Mischoxiden

    Energy Technology Data Exchange (ETDEWEB)

    Stoeckmann, M.

    2000-07-01

    Phenol was to be produced by direct oxidation of benzene with environment-friendly oxidants like hydrogen peroxide, oxygen, or ozone. Catalysts were amorphous microporous mixed oxides whose properties can be selected directly in the sol-gel synthesis process. Apart from benzene, also cyclohexane was oxidized with ozone using AMM catalysts in order to get more information on the potential of ozone as oxidant in heterogeneously catalyzed reactions. [German] Ziel dieser Arbeit war die Herstellung von Phenol durch die Direktoxidation von Benzol mit umweltfreundlichen Oxidationsmitteln wie Wasserstoffperoxid, Sauerstoff oder Ozon. Als Katalysatoren dienten amorphe mikroporoese Mischoxide, da deren Eigenschaften direkt in der Synthese durch den Sol-Gel-Prozess gezielt eingestellt werden koennen. Neben Benzol wurde auch Cyclohexan mit Ozon unter der Verwendung von AMM-Katalysatoren oxidiert, um das Potential von Ozon als Oxiationsmittel in heterogen katalysierten Reaktionen naeher zu untersuchen. (orig.)

  5. Vanadium based amorphous mixed oxides used as negative electrodes of lithium batteries; Oxydes mixtes amorphes a base de vanadium comme electrodes negatives de batteries au lithium

    Energy Technology Data Exchange (ETDEWEB)

    Guyomard, D.; Leroux, F.; Sigala, C.; Le Gal La Salle, A.; Piffard, Y. [Institut des Materiaux de Nantes, 44 (France). Laboratoire de Chimie des Solides

    1996-12-31

    This paper presents recent results concerning the chemical and electrochemical synthesis, the electrochemical properties and the characterization of two new families of amorphous oxides of formula Li{sub x}MVO{sub 4} (1oxides allows the low potential reversible insertion of lithium and can be used as negative electrodes in high performance lithium-ion batteries. (J.S.) 19 refs.

  6. Electrochromism of amorphous ruthenium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Se-Hee; Liu, Ping; Tracy, C. Edwin; Deb, Satyen K. [National Renewable Energy Laboratory, Center for Basic Sciences, 1617 Cole Boulevard, Golden, CO 80401 (United States); Cheong, Hyeonsik M. [Sogang University, Shinsoo-Dong, Seoul 121-742 (Korea, Republic of)

    2003-12-01

    We report on the electrochromic behavior of amorphous ruthenium oxide thin films and their electrochemical characteristics for use as counterelectrodes for electrochromic devices. Hydrous ruthenium oxide thin films were prepared by cyclic voltammetry on ITO coated glass substrates from an aqueous ruthenium chloride solution. The cyclic voltammograms of this material show the capacitive behavior including two redox reaction peaks in each cathodic and anodic scan. The ruthenium oxide thin film electrode exhibits a 50% modulation of optical transmittance at 670 nm wavelength with capacitor charge/discharge.

  7. Role of Amorphous Manganese Oxide in Nitrogen Loss

    Institute of Scientific and Technical Information of China (English)

    LILIANG-MO; WUQI-TU

    1991-01-01

    Studies have been made,by 15N-tracer technique on nitrogen loss resulting from adding amorphous manganese oxide to NH4+-N medium under anaerobic conditions.The fact that the total nitrogen recovery was decreased and that 15NO2,15N2O,15N14NO,15NO,15N2 and 15N14N were emitted has proved that,like amorphous iron oxide,amorphous manganese oxide can also act as an electron acceptor in the oxidation of NH4+-N under anaerobic conditions and give rise to nitrogen loss.This once again illustrates another mechanism by which the loss of ammonium nitrogen in paddy soils is brought about by amorphous iron and manganese oxides.The quantity of nitrogen loss by amorphous manganese oxide increased with an increase in the amount of amorphous manganese oxide added and lessened with time of its aging.The nitrogen loss resulting from amorphous manganese oxide was less than that from amorphous iron oxide.And the nitrogen loss resulting from amorphous manganese oxide was less than that from amorphous iron oxide.And the nitrogen loss by cooperation of amorphous manganese oxide and microorganisms (soil suspension) was larger than that by amorphous manganese oxide alone.In the system,nitrogen loss was associated with the specific surface ares and oxidation-reduction of amorphous manganese oxide.However,their quantitative relationship and the exact reaction processes of nitrogen loss induced by amorphous manganese oxide remain to be further studied.

  8. Unveiling the complex electronic structure of amorphous metal oxides

    OpenAIRE

    Arhammar, C.; Pietzsch, A; Bock, N.; Holmstrom, E.; Araujo, C. M.; Grasjo, J.; Zhao, S.; Green, S; Peery, T.; Hennies, F.; Amerioun, S.; Fohlisch, A.; Schlappa, J.; Schmitt, T; Strocov, V. N.

    2011-01-01

    Amorphous materials represent a large and important emerging area of material’s science. Amorphous oxides are key technological oxides in applications such as a gate dielectric in Complementary metal-oxide semiconductor devices and in Silicon-Oxide-Nitride-Oxide-Silicon and TANOS (TaN-Al2O3-Si3N4-SiO2-Silicon) flash memories. These technologies are required for the high packing density of today’s integrated circuits. Therefore the investigation of defect states in these structures is crucial....

  9. Growth model of lantern-like amorphous silicon oxide nanowires

    Science.gov (United States)

    Wu, Ping; Zou, Xingquan; Chi, Lingfei; Li, Qiang; Xiao, Tan

    2007-03-01

    Silicon oxide nanowire assemblies with lantern-like morphology were synthesized by thermal evaporation of the mixed powder of SnO2 and active carbon at 1000 °C and using the silicon wafer as substrate and source. The nano-lanterns were characterized by a scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), energy-dispersive spectroscope (EDS) and selective area electron diffraction (SAED). The results show that the nano-lantern has symmetrical morphology, with one end connecting with the silicon wafer and the other end being the tin ball. The diameter of the nano-lantern is about 1.5-3.0 µm. Arc silicon oxide nanowire assemblies between the two ends have diameters ranging from 70 to 150 nm. One single catalyst tin ball catalyzes more than one amorphous nanowires' growth. In addition, the growth mechanism of the nano-lantern is discussed and a growth model is proposed. The multi-nucleation sites round the Sn droplet's perimeter are responsible for the formation of many SiOx nanowires. The growing direction of the nanowires is not in the same direction of the movement of the catalyst tin ball, resulting in the bending of the nanowires and forming the lantern-like silicon oxide morphology. The controllable synthesis of the lantern-like silicon oxide nanostructure may have potential applications in the photoelectronic devices field.

  10. Growth model of lantern-like amorphous silicon oxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wu Ping; Zou Xingquan; Chi Lingfei; Li Qiang; Xiao Tan [Department of Physics, Shantou University, Shantou 515063 (China)

    2007-03-28

    Silicon oxide nanowire assemblies with lantern-like morphology were synthesized by thermal evaporation of the mixed powder of SnO{sub 2} and active carbon at 1000 deg. C and using the silicon wafer as substrate and source. The nano-lanterns were characterized by a scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), energy-dispersive spectroscope (EDS) and selective area electron diffraction (SAED). The results show that the nano-lantern has symmetrical morphology, with one end connecting with the silicon wafer and the other end being the tin ball. The diameter of the nano-lantern is about 1.5-3.0 {mu}m. Arc silicon oxide nanowire assemblies between the two ends have diameters ranging from 70 to 150 nm. One single catalyst tin ball catalyzes more than one amorphous nanowires' growth. In addition, the growth mechanism of the nano-lantern is discussed and a growth model is proposed. The multi-nucleation sites round the Sn droplet's perimeter are responsible for the formation of many SiO{sub x} nanowires. The growing direction of the nanowires is not in the same direction of the movement of the catalyst tin ball, resulting in the bending of the nanowires and forming the lantern-like silicon oxide morphology. The controllable synthesis of the lantern-like silicon oxide nanostructure may have potential applications in the photoelectronic devices field.

  11. Nanostructured amorphous nickel oxide with enhanced antioxidant activity

    Energy Technology Data Exchange (ETDEWEB)

    Madhu, G. [Department of Physics, University of Kerala, Kariavattom Campus, Thiruvananthapuram, Kerala 695581 (India); Department of Physics, University College, Thiruvananthapuram, Kerala 695034 (India); Biju, V., E-mail: bijunano@gmail.com [Department of Physics, University of Kerala, Kariavattom Campus, Thiruvananthapuram, Kerala 695581 (India)

    2015-07-15

    Highlights: • Synthesis of nanostructured amorphous nickel oxide by a facile chemical route. • Enhanced antioxidant activity of amorphous NiO compared to crystalline samples. • Role of O{sup 2−} vacancies and high specific surface area in antioxidant activity. • Use of DC conductivity, XPS and BET to explain enhanced antioxidant activity. - Abstract: Nanostructured amorphous nickel oxide was synthesized by the thermal decomposition of nickel chloride–ethanol amine complex. The X-ray diffraction and Transmission Electron Microscopic studies established the amorphous nature of the sample. The Fourier Transform Infrared, Scanning Electron Microscopy, Energy Dispersive and X-ray Photoelectron Spectroscopic studies of the sample revealed the formation of NiO. The specific surface area of the sample is measured using Brunauer–Emmett–Teller analysis and the mesoporous nature of the sample is established through Barrett–Joyner–Halenda pore size distribution analysis. The antioxidant activity of the amorphous sample measured by 1,1-diphenyl-2-picryl hydrazyl (DPPH) scavenging is found to be nearly twice greater than that reported for nanocrystalline NiO samples. The estimated radical scavenging activity of the sample is correlated with the DC conductivity values measured in vacuum and air ambience. The enhanced antioxidant activity of the amorphous NiO is accounted by the increase in the concentration of O{sup 2−} vacancies and the specific surface area. The Ni 2p and O 1s X-ray Photoelectron Spectroscopic studies of the sample support the inference.

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

    Institute of Scientific and Technical Information of China (English)

    GUAN Yong-jun; XIA Yuan

    2005-01-01

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

  13. Tungsten oxide nanowire synthesis from amorphous-like tungsten films.

    Science.gov (United States)

    Seelaboyina, Raghunandan

    2016-03-18

    A synthesis technique which can lead to direct integration of tungsten oxide nanowires onto silicon chips is essential for preparing various devices. The conversion of amorphous tungsten films deposited on silicon chips by pulsed layer deposition to nanowires by annealing is an apt method in that direction. This perspective discusses the ingenious features of the technique reported by Dellasega et al on the various aspects of tungsten oxide nanowire synthesis. PMID:26871521

  14. Determination of carbon in amorphous carbon and uranium monocarbide by oxidation with lead(IV) oxide, copper(II) oxide or barium sulfate in an inert atmosphere

    International Nuclear Information System (INIS)

    Oxidation behavior was studied on amorphous carbon and carbon in uranium monocarbide when lead(IV) oxide, copper(II) oxide and barium sulfate were used as the oxidizing fluxes in helium. The amorphous carbon and the carbon in the carbide were completely extracted with lead oxide in 5 min at 10000C and in 8 min at 700 and 5000C, respectively. Carbon in two samples was quantitatively extracted at 10000C with copper oxide in 8 and 5 min, and with barium sulfate in 7 and 5 min, respectively. The rate of extraction of carbon with copper oxide decreased with decreasing temperature. It was found that the mixing ratio of the oxidizing flux to the amorphous carbon or carbide gave effect on the recovery of carbon. The conventional capillary-trap method which is used for the determination of carbon has a disadvantage that, when carbon dioxide is caught in a cold trap (liquid nitrogen), oxygen is also trapped. This disadvantage was eliminated when a stream of helium was used in place of oxygen. Carbon in the sample can be determined with lead oxide, copper oxide or barium sulfate by extracting carbon dioxide at 10000C for 10 min. (auth.)

  15. Tungsten oxide nanowires grown on amorphous-like tungsten films.

    Science.gov (United States)

    Dellasega, D; Pietralunga, S M; Pezzoli, A; Russo, V; Nasi, L; Conti, C; Vahid, M J; Tagliaferri, A; Passoni, M

    2015-09-11

    Tungsten oxide nanowires have been synthesized by vacuum annealing in the range 500-710 °C from amorphous-like tungsten films, deposited on a Si(100) substrate by pulsed laser deposition (PLD) in the presence of a He background pressure. The oxygen required for the nanowires formation is already adsorbed in the W matrix before annealing, its amount depending on deposition parameters. Nanowire crystalline phase and stoichiometry depend on annealing temperature, ranging from W18O49-Magneli phase to monoclinic WO3. Sufficiently long annealing induces the formation of micrometer-long nanowires, up to 3.6 μm with an aspect ratio up to 90. Oxide nanowire growth appears to be triggered by the crystallization of the underlying amorphous W film, promoting their synthesis at low temperatures. PMID:26292084

  16. Band gap structure modification of amorphous anodic Al oxide film by Ti-alloying

    DEFF Research Database (Denmark)

    Canulescu, Stela; Rechendorff, K.; Borca, C. N.;

    2014-01-01

    The band structure of pure and Ti-alloyed anodic aluminum oxide has been examined as a function of Ti concentration varying from 2 to 20 at. %. The band gap energy of Ti-alloyed anodic Al oxide decreases with increasing Ti concentration. X-ray absorption spectroscopy reveals that Ti atoms...... are not located in a TiO2 unit in the oxide layer, but rather in a mixed Ti-Al oxide layer. The optical band gap energy of the anodic oxide layers was determined by vacuum ultraviolet spectroscopy in the energy range from 4.1 to 9.2 eV (300–135 nm). The results indicate that amorphous anodic Al2O3 has a direct...

  17. Electrochromic study on amorphous tungsten oxide films by sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chuan, E-mail: cli10@yahoo.com [Department of Biomedical Engineering, National Yang Ming University, Taipei 11221, Taiwan (China); Department of Mechanical Engineering, National Central University, Jhongli, Taoyuan 32001, Taiwan (China); Hsieh, J.H. [Department of Materials Engineering, Ming Chi University of Technology, Taishan, Taipei 24301, Taiwan (China); Hung, Ming-Tsung [Department of Mechanical Engineering, National Central University, Jhongli, Taoyuan 32001, Taiwan (China); Huang, B.Q. [Department of Biomedical Engineering, National Yang Ming University, Taipei 11221, Taiwan (China)

    2015-07-31

    Tungsten oxide films under different oxygen flow rates are deposited by DC sputtering. The voltage change at target and analyses for the deposited films by X-ray diffraction, scanning electronic microscope, X-ray photoelectron spectroscopy and ultraviolet–visible-near infrared spectroscopy consistently indicate that low oxygen flow rate (5 sccm) only creates metal-rich tungsten oxide films, while higher oxygen flow rate (10–20 sccm) assures the deposition of amorphous WO{sub 3} films. To explore the electrochromic function of deposited WO{sub 3} films, we use electrochemical tests to perform the insertion of lithium ions and electrons into films. The WO{sub 3} films switch between color and bleach states effectively by both potentiostat and cyclic voltammetry. Quantitative evaluation on electrochemical tests indicates that WO{sub 3} film with composition close to its stoichiometry is an optimal choice for electrochromic function. - Highlights: • Amorphous WO{sub 3} films are deposited by DC sputtering under different O{sub 2} flow rates. • Higher oxygen flow rate (> 10 sccm) assures the deposition of amorphous WO{sub 3} films. • Both potentiostat and cyclic voltammetry make WO{sub 3} films switch its color. • An optimal electrochromic WO{sub 3} is to make films close to its stoichiometry.

  18. Electrochromic study on amorphous tungsten oxide films by sputtering

    International Nuclear Information System (INIS)

    Tungsten oxide films under different oxygen flow rates are deposited by DC sputtering. The voltage change at target and analyses for the deposited films by X-ray diffraction, scanning electronic microscope, X-ray photoelectron spectroscopy and ultraviolet–visible-near infrared spectroscopy consistently indicate that low oxygen flow rate (5 sccm) only creates metal-rich tungsten oxide films, while higher oxygen flow rate (10–20 sccm) assures the deposition of amorphous WO3 films. To explore the electrochromic function of deposited WO3 films, we use electrochemical tests to perform the insertion of lithium ions and electrons into films. The WO3 films switch between color and bleach states effectively by both potentiostat and cyclic voltammetry. Quantitative evaluation on electrochemical tests indicates that WO3 film with composition close to its stoichiometry is an optimal choice for electrochromic function. - Highlights: • Amorphous WO3 films are deposited by DC sputtering under different O2 flow rates. • Higher oxygen flow rate (> 10 sccm) assures the deposition of amorphous WO3 films. • Both potentiostat and cyclic voltammetry make WO3 films switch its color. • An optimal electrochromic WO3 is to make films close to its stoichiometry

  19. Preparation and Characterization of Amorphous Silicon Oxide Nanowires

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Large-scale amorphous silicon nanowires (SiNWs) with a diameter about 100 nm and a length of dozens of micrometers on silicon wafers were synthesized by thermal evaporation of silicon monoxide (SiO).Scanning electron microscope (SEM) and transmission electron microscope (TEM) observations show that the silicon nanowires are smooth.Selected area electron diffraction (SAED) shows that the silicon nanowires are amorphous and energy-dispersive X-ray spectroscopy (EDS) indicates that the nanowires have the composition of Si and O elements in an atomic ratio of 1:2, their composition approximates that of SiO2.SiO is considered to be used as a Si sources to produce SiNWs.We conclude that the growth mechanism is closely related to the defect structure and silicon monoxide followed by growth through an oxide-assisted vapor-solid reaction.

  20. Amorphous Hafnium-Indium-Zinc Oxide Semiconductor Thin Film Transistors

    Directory of Open Access Journals (Sweden)

    Sheng-Po Chang

    2012-01-01

    Full Text Available We reported on the performance and electrical properties of co-sputtering-processed amorphous hafnium-indium-zinc oxide (α-HfIZO thin film transistors (TFTs. Co-sputtering-processed α-HfIZO thin films have shown an amorphous phase in nature. We could modulate the In, Hf, and Zn components by changing the co-sputtering power. Additionally, the chemical composition of α-HfIZO had a significant effect on reliability, hysteresis, field-effect mobility (μFE, carrier concentration, and subthreshold swing (S of the device. Our results indicated that we could successfully and easily fabricate α-HfIZO TFTs with excellent performance by the co-sputtering process. Co-sputtering-processed α-HfIZO TFTs were fabricated with an on/off current ratio of ~106, higher mobility, and a subthreshold slope as steep as 0.55 V/dec.

  1. Bacterial adhesion on amorphous and crystalline metal oxide coatings

    Energy Technology Data Exchange (ETDEWEB)

    Almaguer-Flores, Argelia [Facultad de Odontología, División de Estudios de Posgrado e Investigación, Universidad Nacional Autónoma de México, Circuito exterior s/n, Ciudad Universitaria, 04510 México D.F. (Mexico); Silva-Bermudez, Phaedra, E-mail: suriel21@yahoo.com [Unidad de Ingeniería de Tejidos, Terapia Celular y Medicina Regenerativa, Instituto Nacional de Rehabilitación, Calzada México-Xochimilco No. 289, Col. Arenal de Guadalupe, 14389 México D.F. (Mexico); Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, 04510 México D.F. (Mexico); Galicia, Rey; Rodil, Sandra E. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, 04510 México D.F. (Mexico)

    2015-12-01

    Several studies have demonstrated the influence of surface properties (surface energy, composition and topography) of biocompatible materials on the adhesion of cells/bacteria on solid substrates; however, few have provided information about the effect of the atomic arrangement or crystallinity. Using magnetron sputtering deposition, we produced amorphous and crystalline TiO{sub 2} and ZrO{sub 2} coatings with controlled micro and nanoscale morphology. The effect of the structure on the physical–chemical surface properties was carefully analyzed. Then, we studied how these parameters affect the adhesion of Escherichia coli and Staphylococcus aureus. Our findings demonstrated that the nano-topography and the surface energy were significantly influenced by the coating structure. Bacterial adhesion at micro-rough (2.6 μm) surfaces was independent of the surface composition and structure, contrary to the observation in sub-micron (0.5 μm) rough surfaces, where the crystalline oxides (TiO{sub 2} > ZrO{sub 2}) surfaces exhibited higher numbers of attached bacteria. Particularly, crystalline TiO{sub 2}, which presented a predominant acidic nature, was more attractive for the adhesion of the negatively charged bacteria. The information provided by this study, where surface modifications are introduced by means of the deposition of amorphous or crystalline oxide coatings, offers a route for the rational design of implant surfaces to control or inhibit bacterial adhesion. - Highlights: • Amorphous (a) and crystalline (c) TiO{sub 2} and ZrO{sub 2} coatings were deposited. • The atomic ordering influences the coatings surface charge and nano-topography. • The atomic ordering modifies the bacterial adhesion for the same surface chemistry. • S. aureus adhesion was lower on a-TiO{sub 2} and a-ZrO{sub 2} than on their c-oxide counterpart. • E. coli adhesion on a-TiO{sub 2} was lower than on the c-TiO{sub 2}.

  2. Flexible Electronics Powered by Mixed Metal Oxide Thin Film Transistors

    Science.gov (United States)

    Marrs, Michael

    A low temperature amorphous oxide thin film transistor (TFT) and amorphous silicon PIN diode backplane technology for large area flexible digital x-ray detectors has been developed to create 7.9-in. diagonal backplanes. The critical steps in the evolution of the backplane process include the qualification and optimization of the low temperature (200 °C) metal oxide TFT and a-Si PIN photodiode process, the stability of the devices under forward and reverse bias stress, the transfer of the process to flexible plastic substrates, and the fabrication and assembly of the flexible detectors. Mixed oxide semiconductor TFTs on flexible plastic substrates suffer from performance and stability issues related to the maximum processing temperature limitation of the polymer. A novel device architecture based upon a dual active layer improves both the performance and stability. Devices are directly fabricated below 200 ºC on a polyethylene naphthalate (PEN) substrate using mixed metal oxides of either zinc indium oxide (ZIO) or indium gallium zinc oxide (IGZO) as the active semiconductor. The dual active layer architecture allows for adjustment to the saturation mobility and threshold voltage stability without the requirement of high temperature annealing, which is not compatible with flexible plastic substrates like PEN. The device performance and stability is strongly dependent upon the composition of the mixed metal oxide; this dependency provides a simple route to improving the threshold voltage stability and drive performance. By switching from a single to a dual active layer, the saturation mobility increases from 1.2 cm2/V-s to 18.0 cm2/V-s, while the rate of the threshold voltage shift decreases by an order of magnitude. This approach could assist in enabling the production of devices on flexible substrates using amorphous oxide semiconductors. Low temperature (200°C) processed amorphous silicon photodiodes were developed successfully by balancing the tradeoffs

  3. Amorphous silicon oxide window layers for high-efficiency silicon heterojunction solar cells

    OpenAIRE

    Seif, Johannes Peter; Descoeudres, Antoine; Filipic, Miha; Smole, Franc; Topic, Marko; Holman, Zachary Charles; De Wolf, Stefaan; Ballif, Christophe

    2014-01-01

    In amorphous/crystalline silicon heterojunction solar cells, optical losses can be mitigated by replacing the amorphous silicon films by wider bandgap amorphous silicon oxide layers. In this article, we use stacks of intrinsic amorphous silicon and amorphous silicon oxide as front intrinsic buffer layers and show that this increases the short-circuit current density by up to 0.43 mA/cm2 due to less reflection and a higher transparency at short wavelengths. Additionally, high open-circuit volt...

  4. Synthesis of amorphous zirconium oxide with luminescent characteristics

    International Nuclear Information System (INIS)

    It was prepared zirconium oxide, ZrO2, by means of hydrolysis-condensation reactions (sol-gel method), using zirconium propoxide, Zr(C3H7O)4, as precursor and nitric acid, HNO3, as catalyst of the hydrolysis reaction. In this synthesis it was used a molar ratio water-alkoxide, r=nH2O/nZr(C3H70)4, high, similar to 200, so that the hydrolysis happens quickly and the nucleation and growth are completed in very little time. The solid was characterized with Ftir spectrophotometry, Differential thermal analysis (Dta), Thermal gravimetric analysis (T G), X-ray diffraction of powders, Scanning electron microscopy (Sem) and X-ray Dispersion energy (EDX). The ZrO2 obtained by this way is amorphous even to 300 C and it consists of big aggregates. The amorphous ZrO2, presents thermoluminescent behavior, after it was irradiated with UV radiation and beta particles of 90Sr/90Y and it was thermally stimulated. (Author)

  5. Optoelectronic properties of valence-state-controlled amorphous niobium oxide

    Science.gov (United States)

    Onozato, Takaki; Katase, Takayoshi; Yamamoto, Akira; Katayama, Shota; Matsushima, Koichi; Itagaki, Naho; Yoshida, Hisao; Ohta, Hiromichi

    2016-06-01

    In order to understand the optoelectronic properties of amorphous niobium oxide (a-NbO x ), we have investigated the valence states, local structures, electrical resistivity, and optical absorption of a-NbO x thin films with various oxygen contents. It was found that the valence states of Nb ion in a-NbO x films can be controlled from 5+  to 4+  by reducing oxygen pressure during film deposition at room temperature, together with changing the oxide-ion arrangement around Nb ion from Nb2O5-like to NbO2-like local structure. As a result, a four orders of magnitude reduction in the electrical resistivity of a-NbO x films was observed with decreasing oxygen content, due to the carrier generation caused by the appearance and increase of an oxygen-vacancy-related subgap state working as an electron donor. The tunable optoelectronic properties of a-NbO x films by valence-state-control with oxygen-vacancy formation will be useful for potential flexible optoelectronic device applications.

  6. Optoelectronic properties of valence-state-controlled amorphous niobium oxide.

    Science.gov (United States)

    Onozato, Takaki; Katase, Takayoshi; Yamamoto, Akira; Katayama, Shota; Matsushima, Koichi; Itagaki, Naho; Yoshida, Hisao; Ohta, Hiromichi

    2016-06-29

    In order to understand the optoelectronic properties of amorphous niobium oxide (a-NbO x ), we have investigated the valence states, local structures, electrical resistivity, and optical absorption of a-NbO x thin films with various oxygen contents. It was found that the valence states of Nb ion in a-NbO x films can be controlled from 5+  to 4+  by reducing oxygen pressure during film deposition at room temperature, together with changing the oxide-ion arrangement around Nb ion from Nb2O5-like to NbO2-like local structure. As a result, a four orders of magnitude reduction in the electrical resistivity of a-NbO x films was observed with decreasing oxygen content, due to the carrier generation caused by the appearance and increase of an oxygen-vacancy-related subgap state working as an electron donor. The tunable optoelectronic properties of a-NbO x films by valence-state-control with oxygen-vacancy formation will be useful for potential flexible optoelectronic device applications. PMID:27168317

  7. Bacterial nanometric amorphous Fe-based oxide: a potential lithium-ion battery anode material.

    Science.gov (United States)

    Hashimoto, Hideki; Kobayashi, Genki; Sakuma, Ryo; Fujii, Tatsuo; Hayashi, Naoaki; Suzuki, Tomoko; Kanno, Ryoji; Takano, Mikio; Takada, Jun

    2014-04-23

    Amorphous Fe(3+)-based oxide nanoparticles produced by Leptothrix ochracea, aquatic bacteria living worldwide, show a potential as an Fe(3+)/Fe(0) conversion anode material for lithium-ion batteries. The presence of minor components, Si and P, in the original nanoparticles leads to a specific electrode architecture with Fe-based electrochemical centers embedded in a Si, P-based amorphous matrix.

  8. Fabrication of amorphous silicon nanoribbons by atomic force microscope tip induced local oxidation for thin film device applications

    OpenAIRE

    Pichon, Laurent; Rogel, Regis; Demami, Fouad

    2010-01-01

    WOS International audience We demonstrate the feasibility of induced local oxidation of amorphous silicon by atomic force microscopy. The resulting local oxide is used as mask for the elaboration of thin film silicon resistor. A thin amorphous silicon layer deposited on a glass substrate is locally oxidized following narrow continuous lines. The corresponding oxide line is then used as mask during plasma etching of the amorphous layer leading to the formation of nanoribbon. Such amorpho...

  9. Mixed oxide conversion facility alternative conceptual designs

    International Nuclear Information System (INIS)

    Allied-General Nuclear Services recently performed studies to evaluate alternative proliferation-resistant flowsheets of the uranium-based LWR fuel cycle. The alternatives evaluated consist of coprocessing schemes with either a gamma or a heat spike added. A literature search and evaluation were performed to select a process technology for mixed oxide coconversion. The COPRECAL process was chosen as the most suitable conversion process technology. Three alternative mixed oxide conversion facility design concepts were prepared based on the COPRECAL technology. These alternative concepts are compared to a pure plutonium conversion facility. Facility designs, relative proliferation resistance, and cost estimates are discussed

  10. Remarkably stable amorphous metal oxide grown on Zr-Cu-Be metallic glass.

    Science.gov (United States)

    Lim, Ka Ram; Kim, Chang Eun; Yun, Young Su; Kim, Won Tae; Soon, Aloysius; Kim, Do Hyang

    2015-12-14

    In the present study, we investigated the role of an aliovalent dopant upon stabilizing the amorphous oxide film. We added beryllium into the Zr50Cu50 metallic glass system, and found that the amorphous oxide layer of Be-rich phase can be stabilized even at elevated temperature above Tg of the glass matrix. The thermal stability of the amorphous oxide layer is substantially enhanced due to Be addition. As confirmed by high-temperature cross-section HR-TEM, fully disordered Be-added amorphous layer is observed, while the rapid crystallization is observed without Be. To understand the role of Be, we employed ab-initio molecular dynamics to compare the mobility of ions with/without Be dopant, and propose a disordered model where Be dopant occupies Zr vacancy and induces structural disorder to the amorphous phase. We find that the oxygen mobility is slightly suppressed due to Be dopant, and Be mobility is unexpectedly lower than that of oxygen, which we attribute to the aliovalent nature of Be dopant whose diffusion always accompany multiple counter-diffusion of other ions. Here, we explain the origin of superior thermal stability of amorphous oxide film in terms of enhanced structural disorder and suppressed ionic mobility due to the aliovalent dopant.

  11. Packing and the structural transformations in liquid and amorphous oxides from ambient to extreme conditions

    OpenAIRE

    Zeidler, Anita; Salmon, Philip Stephen; Skinner, Lawrie Basil

    2014-01-01

    The structures of liquid and amorphous oxides are difficult to solve because of the complexity of their disordered networks, and the adaptability in size of oxide ions to their coordination environments. Particular difficulty is therefore associated with an identification of generic features associated with structural transformations. This paper adopts an empirical approach to find the oxide ion size, and shows that the network structures of a wide variety of disordered oxides can be categori...

  12. Fabrication method for mixed oxide fuel

    International Nuclear Information System (INIS)

    A mixed oxide fuel fabrication method is described which uses a starting material of an oxide of one fuel in the form of spherical particles of two size fractions, fine and coarse, sintering the fine fraction to full density, sintering the coarse fraction to a predetermined density, impregnating the coarse fraction with a salt of a second fuel material and treating this fraction to convert the impregnating material to an oxide, and then loading both fractions into a fuel element. In the preferred process three size fractions are used, i.e. fine, medium, and coarse, with only the coarse fraction being subject to the impregnation step. (LL)

  13. Mixed iron-manganese oxide nanoparticles

    NARCIS (Netherlands)

    Lai, Jriuan; Shafi, Kurikka V.P.M.; Ulman, Abraham; Loos, Katja; Yang, Nan-Loh; Cui, Min-Hui; Vogt, Thomas; Estournès, Claude; Locke, Dave C.

    2004-01-01

    Designing nanoparticles for practical applications requires knowledge and control of how their desired properties relate to their composition and structure. Here, we present a detailed systematic study of mixed iron-manganese oxide nanoparticles, showing that ultrasonication provides the high-energy

  14. Long-range structural correlations in amorphous ternary In-based oxides

    Science.gov (United States)

    Khanal, Rabi; Medvedeva, Julia

    2015-03-01

    In recent years, there is an increasing shift towards the use of oxide semiconductor materials in their amorphous form owing to several technological advantages and the fact that amorphous oxides exhibit similar or even superior properties than their crystalline counterparts. In this work we have systemically investigated the effect of chemical composition and oxygen stoichiometry on the local and long-range structure of ternary amorphous oxides, namely In-X-O with X =Sn, Zn, Ga, Cd, Ge, Sc, Y, or La, by means of ab-initio molecular dynamics. The results reveal that the local MO structure remains nearly intact upon amorphization and exhibit weak dependence on the composition. In marked contrast, the structural characteristics of the metal-metal shell, namely, the M-M distances and M-O-M angles that determine how MO polyhedra are connected into a network, are affected by the presence of X. Complex interplay between several factors such as the cation ionic size, metal-oxygen bond strength, as well as the natural preference for edge, corner, or face-sharing between the MO polyhedra, leads to a correlated behavior in the long-range structure. These findings highlight the mechanisms of the amorphous structure formation as well as the species of the carrier transport in these oxides.

  15. Electro-oxidation of ethylene glycol on nanoporous Ti-Cu amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Chen Cuijie [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Zhu Shengli, E-mail: slzhu@tju.edu.cn [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China); Yang Xianjin [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China); Pi Lele; Cui Zhenduo [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)

    2011-11-30

    Highlights: > Nanoporous Ti-Cu amorphous alloy exhibits apparent EG electrocatalytic ability EG electro-oxidation occurs more easily in alkaline medium than in acid medium. > In acid medium, heat treatment plays an enhancing role towards EG oxidation. > In alkaline medium, heat treatment has opposite effect below and above 0.1 V. - Abstract: This work describes ethylene glycol (EG) electro-oxidation over nanoporous structure catalyst prepared by dealloying Ti-Cu amorphous alloy. Scanning electron microscopy (SEM) was used to characterize nanoporous catalysts. Electrocatalytic performances in acid and alkaline mediums were measured by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). The results showed that nanoporous Ti-Cu amorphous alloy exhibited apparent electrocatalytic ability in terms of higher oxidation current in CV and CA curves comparing to raw Ti-Cu amorphous alloy. Electro-oxidation of EG took place more easily in alkaline medium than that in acid medium. In acid medium, heat treatment improved the electrocatalytic activity of nanoporous catalyst. In alkaline medium, heat treatment played an enhancing role below 0.1 V and a depressing role above 0.1 V. Possible electro-oxidation mechanism of EG was also discussed.

  16. Transition metal oxide window layer in thin film amorphous silicon solar cells

    International Nuclear Information System (INIS)

    Pin-type hydrogenated amorphous silicon solar cells have been fabricated by replacing state of the art silicon based window layer with more transparent transition metal oxide (TMO) materials. Three kinds of TMOs: vanadium oxide, tungsten oxide, and molybdenum oxide (MoOx) were comparatively investigated to reveal the design principles of metal oxide window layers. It was found that MoOx exhibited the best performance due to its higher work function property compared to other materials. In addition, the band alignment between MoOx and amorphous Si controls the series resistance, which was verified through compositional variation of MoOx thin films. The design principles of TMO window layer in amorphous Si solar cells are summarized as follows: A wide optical bandgap larger than 3.0 eV, a high work function larger than 5.2 eV, and a band alignment condition rendering efficient hole collection from amorphous Si absorber layer. - Highlights: • High work function metal oxides can potentially replace the conventional p-a-SiC. • V2Ox, WOx, and MoOx are comparatively investigated in this study. • MoOx is the most relevant material due to its highest work function. • Slightly oxygen deficient MoOx exhibited performance enhancement at x = 2.9

  17. Aqueous ultracapacitors using amorphous MnO2 and reduced graphene oxide

    Science.gov (United States)

    Mery, Adrien; Ghamouss, Fouad; Autret, Cécile; Farhat, Douaa; Tran-Van, François

    2016-02-01

    Herein, synthesis and characterization of amorphous MnO2 and application in asymmetric aqueous ultracapacitors are reported. Different amorphous manganese oxide (MnO2) materials were synthesized from the reduction of KMnO4 in different media such as ethanol (EtOH) or dimethylformamide (DMF). The electrochemical behavior of amorphous MnO2, labeled MnO2-Et and MnO2-DMF, were studied by using cyclic voltammetry, impedance spectroscopy, and galvanostatic cycling in aqueous electrolyte. XRD, BET, TEM, and SEM characterizations highlighted the amorphous nature and the nanostructuration of these MnO2 materials. BET measurement established that these amorphous MnO2 are mesoporous. In addition, MnO2-Et exhibits a larger specific surface area (168 m2 g-1), a narrower pore diameters distribution with lower diameters compared to MnO2-DMF. These results are in agreement with the electrochemical results. Indeed, MnO2-Et shows a higher specific capacitance and lower impedance in aqueous K2SO4 electrolyte. Furthermore, aqueous asymmetric ultracapacitors were assembled and studied using amorphous MnO2 as positive electrode and reduced graphene oxide (rGO) as negative electrode. These asymmetric systems exhibit an electrochemical stability for more than 20,000 galvanostatic cycles at current density of 1 A g-1 with an operating voltage of 2 V.

  18. Improved Photo-Induced Stability in Amorphous Metal-Oxide Based TFTs for Transparent Displays.

    Science.gov (United States)

    Koo, Sang-Mo; Ha, Tae-Jun

    2015-10-01

    In this paper, we investigate the origin of photo-induced instability in amorphous metal-oxide based thin-film transistors (oxide-TFTs) by exploring threshold voltage (Vth) shift in transfer characteristics. The combination of photo irradiation and prolonged gate bias stress enhanced the shift in Vth in amorphous hafnium-indium-zinc-oxide (a-HfIZO) TFTs. Such results stem from the extended trapped charges at the localized defect states related to oxygen vacancy which play a role in a screening effect on the electric field induced by gate voltage. We also demonstrate the chemically clean interface in oxide-TFTs by employing oxygen annealing which reduces the density of trap states, thereby resulting in improved photo-induced stability. We believe that this work stimulates the research society of transparent electronics by providing a promising approach to suppress photo-induced instability in metal-oxide TFTs. PMID:26726416

  19. Amorphous semiconducting and conducting transparent metal oxide thin films and production thereof

    Science.gov (United States)

    Perkins, John; Van Hest, Marinus Franciscus Antonius Maria; Ginley, David; Taylor, Matthew; Neuman, George A.; Luten, Henry A.; Forgette, Jeffrey A.; Anderson, John S.

    2010-07-13

    Metal oxide thin films and production thereof are disclosed. An exemplary method of producing a metal oxide thin film may comprise introducing at least two metallic elements and oxygen into a process chamber to form a metal oxide. The method may also comprise depositing the metal oxide on a substrate in the process chamber. The method may also comprise simultaneously controlling a ratio of the at least two metallic elements and a stoichiometry of the oxygen during deposition. Exemplary amorphous metal oxide thin films produced according to the methods herein may exhibit highly transparent properties, highly conductive properties, and/or other opto-electronic properties.

  20. Amorphous state in the mixed phase of quark-hadron phase transition in protoneutron stars

    CERN Document Server

    Yasutake, Nobutoshi; Tatsumi, Toshitaka

    2012-01-01

    We study the quark-hadron mixed phase in protoneutron stars, where neutrinos are trapped and lepton number becomes a conserved quantity besides the baryon number and electric charge. Considering protoneutron star matter as a ternary system, the Gibbs conditions are applied together with the Coulomb interaction. We find there appears no crystalline ("pasta") structure in the regime of high lepton-number fraction; the size of pasta becomes very large and the geometrical structure becomes mechanically unstable due to the charge screening effect. Consequently the whole system is separated into two bulk regions like an amorphous state, where the surface effect is safely neglected. The local charge neutrality is approximately attained there. After neutrinos are ejected, the matter becomes a binary system. Charge neutrality is globally ensured and the pasta structures appear there. These features are important to consider the quark-hadron phase transition during the evolution of protoneutron stars.

  1. Deep subgap feature in amorphous indium gallium zinc oxide: Evidence against reduced indium

    Energy Technology Data Exchange (ETDEWEB)

    Sallis, Shawn; Williams, Deborah S. [Materials Science and Engineering, Binghamton University, Binghamton, New York, 13902 (United States); Quackenbush, Nicholas F.; Senger, Mikell [Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, New York, 13902 (United States); Woicik, Joseph C. [Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899 (United States); White, Bruce E.; Piper, Louis F.J. [Materials Science and Engineering, Binghamton University, Binghamton, New York, 13902 (United States); Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, New York, 13902 (United States)

    2015-07-15

    Amorphous indium gallium zinc oxide (a-IGZO) is the archetypal transparent amorphous oxide semiconductor. Despite the gains made with a-IGZO over amorphous silicon in the last decade, the presence of deep subgap states in a-IGZO active layers facilitate instabilities in thin film transistor properties under negative bias illumination stress. Several candidates could contribute to the formation of states within the band gap. Here, we present evidence against In{sup +} lone pair active electrons as the origin of the deep subgap features. No In{sup +} species are observed, only In{sup 0} nano-crystallites under certain oxygen deficient growth conditions. Our results further support under coordinated oxygen as the source of the deep subgap states. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Amorphous transparent conducting oxides in context: Work function survey, trends, and facile modification

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, T.C. [Department of Materials Science and Engineering, Northwestern University, Evanston, IL (United States); Material Sciences Division, Argonne National Laboratory, Lemont, IL (United States); Zhu, Q.; Buchholz, D.B. [Department of Materials Science and Engineering, Northwestern University, Evanston, IL (United States); Martinson, A.B. [Material Sciences Division, Argonne National Laboratory, Lemont, IL (United States); Chang, R.P.H. [Department of Materials Science and Engineering, Northwestern University, Evanston, IL (United States); Mason, T.O., E-mail: t-mason@northwestern.edu [Department of Materials Science and Engineering, Northwestern University, Evanston, IL (United States)

    2015-03-01

    Highlights: • The work function of amorphous TCOs (by PLD) were measured using the Kelvin Probe. • The work functions of oxide combinations were between those of the endpoint oxides. • The work function may be modified by adding ALD layers on the surface of the film. - Abstract: The work functions of various amorphous and crystalline transparent conducting oxides (TCOs) were measured using Kelvin probe. The films, made by pulsed laser deposition, exhibited varying work functions dependent on the composition and deposition parameters. Tin oxide showed the largest work functions of the oxides measured, while zinc oxide showed the lowest. Binary and ternary combinations of the basis TCOs showed intermediate work functions dependent on the endpoint components. Amorphous TCOs, important in OPV and other technological applications, exhibited similar work functions to their crystalline counterparts. UV/ozone treatment of TCOs temporarily increased the work function, consistent with proposed defect mechanisms associated with near-surface changes in carrier content and Fermi level. Finally, a method for facile adjustment of the work function of commercial TCOs by atomic layer deposition (ALD) capping layers was presented, illustrated by the growth of zinc oxide layers on commercial crystalline ITO films.

  3. Selective propene oxidation on mixed metal oxide catalysts

    CERN Document Server

    James, D W

    2002-01-01

    Selective catalytic oxidation processes represent a large segment of the modern chemical industry and a major application of these is the selective partial oxidation of propene to produce acrolein. Mixed metal oxide catalysts are particularly effective in promoting this reaction, and the two primary candidates for the industrial process are based on iron antimonate and bismuth molybdate. Some debate exists in the literature regarding the operation of these materials and the roles of their catalytic components. In particular, iron antimonate catalysts containing excess antimony are known to be highly selective towards acrolein, and a variety of proposals for the enhanced selectivity of such materials have been given. The aim of this work was to provide a direct comparison between the behaviour of bismuth molybdate and iron antimonate catalysts, with additional emphasis being placed on the component single oxide phases of the latter. Studies were also extended to other antimonate-based catalysts, including coba...

  4. Formation of amorphous Ti alloy layers by excimer laser mixing of Ti on AISI 304 stainless-steel surfaces

    Science.gov (United States)

    Jervis, T. R.; Nastasi, M.; Zocco, T. G.; Martin, J. A.

    1988-07-01

    We used excimer laser radiation at 308 nm to mix thin layers of Ti into AISI 304 stainless steel. Different numbers of shots at a fluence about twice the threshold for melting varied the amount of mixing. When mixing is sufficiently complete, an amorphous surface layer is formed with Ti substituting for Fe on a one-to-one basis in the alloy. The laser mixing process, unlike Ti ion implantation, does not result in high incorporation of C in the processed layer, although some C from surface and interface contamination is incorporated into the surface layer.

  5. Heterogeneous catalysis of mixed oxides perovskite and heteropoly catalysts

    CERN Document Server

    Misono, M

    2014-01-01

    Mixed oxides are the most widely used catalyst materials for industrial catalytic processes. The principal objective of this book is to describe systematically the mixed oxide catalysts, from their fundamentals through their practical applications.  After describing concisely general items concerning mixed oxide and mixed oxide catalysts, two important mixed oxide catalyst materials, namely, heteropolyacids and perovskites, are taken as typical examples and discussed in detail. These two materials have several advantages: 1. They are, respectively, typical examples of salts of oxoacids an

  6. An amorphous phase formation at palladium / silicon oxide (Pd/SiOx) interface through electron irradiation - electronic excitation process

    International Nuclear Information System (INIS)

    A Pd-Si amorphous phase was formed at a palladium/silicon oxide (Pd/SiOx) interface at room temperature by electron irradiation at acceleration voltages ranging between 25 kV and 200 kV. Solid-state amorphization was stimulated without the electron knock-on effects. The total dose required for the solid-state amorphization decreases with decreasing acceleration voltage. This is the first report on electron irradiation induced metallic amorphous formation caused by the electronic excitation at metal/silicon oxide interface

  7. Widespread oxidized and hydrated amorphous silicates in CR chondrites matrices: Implications for alteration conditions and H2 degassing of asteroids

    Science.gov (United States)

    Le Guillou, Corentin; Changela, Hitesh G.; Brearley, Adrian J.

    2015-06-01

    The CR chondrites carry one of the most pristine records of the solar nebula materials that accreted to form planetesimals. They have experienced very variable degrees of aqueous alteration, ranging from incipient alteration in their matrices to the complete hydration of all of their components. In order to constrain their chemical alteration pathways and the conditions of alteration, we have investigated the mineralogy and Fe oxidation state of silicates in the matrices of 8 CR chondrites, from type 3 to type 1. Fe-L edge X-ray Absorption Near Edge Structure (XANES) was performed on matrix FIB sections using synchrotron-based scanning transmission X-ray microscopy (STXM). The Fe3+ / ∑ Fe ratio of submicron silicate particles was obtained and coordinated with TEM observations. In all the least altered CR chondrites (QUE 99177, EET 87770, EET 92042, LAP 02342, GRA 95229 and Renazzo), we find that the matrices consist of abundant submicron Fe-rich hydrated amorphous silicate grains, mixed with nanometer-sized phyllosilicates. The Fe3+ / ∑ Fe ratios of both amorphous and nanocrystalline regions are very high with values ranging from 68 to 78%. In the most altered samples (Al Rais and GRO 95577), fine-grained phyllosilicates also have a high Fe3+ / ∑ Fe ratio (around 70%), whereas the coarse, micrometer-sized phyllosilicates are less oxidized (down to 55%) and have a lower iron content. These observations suggest the following sequence: submicron Fe2+-amorphous silicate particles were the building blocks of CR matrices; after accretion they were quickly hydrated and oxidized, leading to a metastable, amorphous gel-like phase. Nucleation and growth of crystalline phyllosilicates was kinetically-limited in most type 3 and 2 CRs, but increased as alteration became more extensive in Al Rais and GRO 95577. The decreasing Fe3+ / ∑ Fe ratio is interpreted as a result of the transfer of Fe3+ from silicates to oxides during growth, while aqueous alteration progressed

  8. Metallic and Insulating Interfaces of Amorphous SrTiO3-Based Oxide Heterostructures

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Pryds, Nini; Kleibeuker, Josée E.;

    2011-01-01

    The conductance confined at the interface of complex oxide heterostructures provides new opportunities to explore nanoelectronic as well as nanoionic devices. Herein we show that metallic interfaces can be realized in SrTiO3-based heterostructures with various insulating overlayers of amorphous La......AlO3, SrTiO3, and yttria-stabilized zirconia films. On the other hand, samples of amorphous La7/8Sr1/8MnO3 films on SrTiO3 substrates remain insulating. The interfacial conductivity results from the formation of oxygen vacancies near the interface, suggesting that the redox reactions on the surface...

  9. Room-temperature fabrication of light-emitting thin films based on amorphous oxide semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Junghwan, E-mail: JH.KIM@lucid.msl.titech.ac.jp; Miyokawa, Norihiko; Ide, Keisuke [Materials and Structures Laboratory, Tokyo Institute of Technology, Mailbox R3-4, 4259 Nagatsuta, Midori-ku, Yokohama (Japan); Toda, Yoshitake [Materials Research Center for Element Strategy, Tokyo Institute of Technology, Mailbox SE-6, 4259 Nagatsuta, Midori-ku, Yokohama (Japan); Hiramatsu, Hidenori; Hosono, Hideo; Kamiya, Toshio [Materials and Structures Laboratory, Tokyo Institute of Technology, Mailbox R3-4, 4259 Nagatsuta, Midori-ku, Yokohama (Japan); Materials Research Center for Element Strategy, Tokyo Institute of Technology, Mailbox SE-6, 4259 Nagatsuta, Midori-ku, Yokohama (Japan)

    2016-01-15

    We propose a light-emitting thin film using an amorphous oxide semiconductor (AOS) because AOS has low defect density even fabricated at room temperature. Eu-doped amorphous In-Ga-Zn-O thin films fabricated at room temperature emitted intense red emission at 614 nm. It is achieved by precise control of oxygen pressure so as to suppress oxygen-deficiency/excess-related defects and free carriers. An electronic structure model is proposed, suggesting that non-radiative process is enhanced mainly by defects near the excited states. AOS would be a promising host for a thin film phosphor applicable to flexible displays as well as to light-emitting transistors.

  10. A mixed flow reactor method to synthesize amorphous calcium carbonate under controlled chemical conditions.

    Science.gov (United States)

    Blue, Christina R; Rimstidt, J Donald; Dove, Patricia M

    2013-01-01

    This study describes a new procedure to synthesize amorphous calcium carbonate (ACC) from well-characterized solutions that maintain a constant supersaturation. The method uses a mixed flow reactor to prepare ACC in significant quantities with consistent compositions. The experimental design utilizes a high-precision solution pump that enables the reactant solution to continuously flow through the reactor under constant mixing and allows the precipitation of ACC to reach steady state. As a proof of concept, we produced ACC with controlled Mg contents by regulating the Mg/Ca ratio of the input solution and the carbonate concentration and pH. Our findings show that the Mg/Ca ratio of the reactant solution is the primary control for the Mg content in ACC, as shown in previous studies, but ACC composition is further regulated by the carbonate concentration and pH of the reactant solution. The method offers promise for quantitative studies of ACC composition and properties and for investigating the role of this phase as a reactive precursor to biogenic minerals.

  11. Critical experiments with mixed oxide fuel

    Energy Technology Data Exchange (ETDEWEB)

    Harris, D.R. [Rensselaer Polytechnic Institute, Troy, NY (United States)

    1997-06-01

    This paper very briefly outlines technical considerations in performing critical experiments on weapons-grade plutonium mixed oxide fuel assemblies. The experiments proposed would use weapons-grade plutonium and Er{sub 2}O{sub 3} at various dissolved boron levels, and for specific fuel assemblies such as the ABBCE fuel assembly with five large water holes. Technical considerations described include the core, the measurements, safety, security, radiological matters, and licensing. It is concluded that the experiments are feasible at the Rensselaer Polytechnic Institute Reactor Critical Facility. 9 refs.

  12. Intrinsic nature of visible-light absorption in amorphous semiconducting oxides

    Directory of Open Access Journals (Sweden)

    Youngho Kang

    2014-03-01

    Full Text Available To enlighten microscopic origin of visible-light absorption in transparent amorphous semiconducting oxides, the intrinsic optical property of amorphous InGaZnO4 is investigated by considering dipole transitions within the quasiparticle band structure. In comparison with the crystalline InGaZnO4 with the optical gap of 3.6 eV, the amorphous InGaZnO4 has two distinct features developed in the band structure that contribute to significant visible-light absorption. First, the conduction bands are down-shifted by 0.55 eV mainly due to the undercoordinated In atoms, reducing the optical gap between extended states to 2.8 eV. Second, tail states formed by localized oxygen p orbitals are distributed over ∼0.5 eV near the valence edge, which give rise to substantial subgap absorption. The fundamental understanding on the optical property of amorphous semiconducting oxides based on underlying electronic structure will pave the way for resolving instability issues in recent display devices incorporating the semiconducting oxides.

  13. Generalized molybdenum oxide surface chemical state XPS determination via informed amorphous sample model

    Energy Technology Data Exchange (ETDEWEB)

    Baltrusaitis, Jonas, E-mail: job314@lehigh.edu [Department of Chemical Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA 18015 (United States); PhotoCatalytic Synthesis group, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, Meander 229, P.O. Box 217, 7500 AE Enschede (Netherlands); Mendoza-Sanchez, Beatriz [CRANN, Chemistry School, Trinity College Dublin, Dublin (Ireland); Fernandez, Vincent [Institut des Matériaux Jean Rouxel, 2 rue de la Houssinière, BP 32229, F-44322 Nantes Cedex 3 (France); Veenstra, Rick [PhotoCatalytic Synthesis group, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, Meander 229, P.O. Box 217, 7500 AE Enschede (Netherlands); Dukstiene, Nijole [Department of Physical and Inorganic Chemistry, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas (Lithuania); Roberts, Adam [Kratos Analytical Ltd, Trafford Wharf Road, Wharfside, Manchester, M17 1GP (United Kingdom); Fairley, Neal [Casa Software Ltd, Bay House, 5 Grosvenor Terrace, Teignmouth, Devon TQ14 8NE (United Kingdom)

    2015-01-30

    Highlights: • We analyzed and modeled spectral envelopes of complex molybdenum oxides. • Molybdenum oxide films of varying valence and crystallinity were synthesized. • MoO{sub 3} and MoO{sub 2} line shapes from experimental data were created. • Informed amorphous sample model (IASM) developed. • Amorphous molybdenum oxide XPS envelopes were interpreted. - Abstract: Accurate elemental oxidation state determination for the outer surface of a complex material is of crucial importance in many science and engineering disciplines, including chemistry, fundamental and applied surface science, catalysis, semiconductors and many others. X-ray photoelectron spectroscopy (XPS) is the primary tool used for this purpose. The spectral data obtained, however, is often very complex and can be subject to incorrect interpretation. Unlike traditional XPS spectra fitting procedures using purely synthetic spectral components, here we develop and present an XPS data processing method based on vector analysis that allows creating XPS spectral components by incorporating key information, obtained experimentally. XPS spectral data, obtained from series of molybdenum oxide samples with varying oxidation states and degree of crystallinity, were processed using this method and the corresponding oxidation states present, as well as their relative distribution was elucidated. It was shown that monitoring the evolution of the chemistry and crystal structure of a molybdenum oxide sample due to an invasive X-ray probe could be used to infer solutions to complex spectral envelopes.

  14. Oxidative Damage and Energy Metabolism Disorder Contribute to the Hemolytic Effect of Amorphous Silica Nanoparticles.

    Science.gov (United States)

    Jiang, Lizhen; Yu, Yongbo; Li, Yang; Yu, Yang; Duan, Junchao; Zou, Yang; Li, Qiuling; Sun, Zhiwei

    2016-12-01

    Amorphous silica nanoparticles (SiNPs) have been extensively used in biomedical applications due to their particular characteristics. The increased environmental and iatrogenic exposure of SiNPs gained great concerns on the biocompatibility and hematotoxicity of SiNPs. However, the studies on the hemolytic effects of amorphous SiNPs in human erythrocytes are still limited. In this study, amorphous SiNPs with 58 nm were selected and incubated with human erythrocytes for different times (30 min and 2 h) at various concentrations (0, 10, 20, 50, and 100 μg/mL). SiNPs induced a dose-dependent increase in percent hemolysis and significantly increased the malondialdehyde (MDA) content and decreased the superoxide dismutase (SOD) activity, leading to oxidative damage in erythrocytes. Hydroxyl radical (·OH) levels were detected by electron spin resonance (ESR), and the decreased elimination rates of ·OH showed SiNPs induced low antioxidant ability in human erythrocytes. Na(+)-K(+) ATPase activity and Ca(2+)-Mg(2+) ATPase activity were found remarkably inhibited after SiNP treatment, possibly causing energy sufficient in erythrocytes. Percent hemolysis of SiNPs was significantly decreased in the presence of N-acetyl-cysteine (NAC) and adenosine diphosphate (ADP). It was concluded that amorphous SiNPs caused dose-dependent hemolytic effects in human erythrocytes. Oxidative damage and energy metabolism disorder contributed to the hemolytic effects of SiNPs in vitro. PMID:26831695

  15. Oxidative Damage and Energy Metabolism Disorder Contribute to the Hemolytic Effect of Amorphous Silica Nanoparticles

    Science.gov (United States)

    Jiang, Lizhen; Yu, Yongbo; Li, Yang; Yu, Yang; Duan, Junchao; Zou, Yang; Li, Qiuling; Sun, Zhiwei

    2016-02-01

    Amorphous silica nanoparticles (SiNPs) have been extensively used in biomedical applications due to their particular characteristics. The increased environmental and iatrogenic exposure of SiNPs gained great concerns on the biocompatibility and hematotoxicity of SiNPs. However, the studies on the hemolytic effects of amorphous SiNPs in human erythrocytes are still limited. In this study, amorphous SiNPs with 58 nm were selected and incubated with human erythrocytes for different times (30 min and 2 h) at various concentrations (0, 10, 20, 50, and 100 μg/mL). SiNPs induced a dose-dependent increase in percent hemolysis and significantly increased the malondialdehyde (MDA) content and decreased the superoxide dismutase (SOD) activity, leading to oxidative damage in erythrocytes. Hydroxyl radical (·OH) levels were detected by electron spin resonance (ESR), and the decreased elimination rates of ·OH showed SiNPs induced low antioxidant ability in human erythrocytes. Na+-K+ ATPase activity and Ca2+-Mg2+ ATPase activity were found remarkably inhibited after SiNP treatment, possibly causing energy sufficient in erythrocytes. Percent hemolysis of SiNPs was significantly decreased in the presence of N-acetyl-cysteine (NAC) and adenosine diphosphate (ADP). It was concluded that amorphous SiNPs caused dose-dependent hemolytic effects in human erythrocytes. Oxidative damage and energy metabolism disorder contributed to the hemolytic effects of SiNPs in vitro.

  16. The beneficial effect of nanocrystalline and amorphous nature on the anode performance of manganese oxide for lithium ion batteries

    International Nuclear Information System (INIS)

    Highlights: • A soft-chemical redox reaction yields efficient anode material of amorphous MnO2 nanocrystal. • Amorphous MnO2 nanocrystal shows better anode performance than well-crystalline homologue. • This result highlights the merit of nanocrystalline nature for the electrode performance of MnO2. • The present redox reaction provides a scalable and economic route to efficient anode material. - Abstract: The effect of the amorphous structure and nanocrystalline nature of metal oxide on its anode performance in lithium ion batteries is investigated with two nanocrystalline and one well-crystallized layered manganese oxides. X-ray amorphous manganese oxide nanocrystals are synthesized by soft-chemical redox reactions using reducing agents of KBH4 and LiI at room temperature, whereas well-crystallized layered manganese oxide is obtained by solid state reaction at elevated temperature. Although both of the amorphous manganese oxides lack a long-range structural order, they are crystallized with a layered MnO2-type local structure, which is nearly identical to the crystal structure of the well-crystallized K0.45MnO2. In comparison with the well-crystallized K0.45MnO2, both the amorphous manganese oxides commonly possess smaller particle sizes with larger surface areas and better homogeneity of composite structure. The amorphous manganese oxide nanocrystals show better anode performance with greater discharge capacity for lithium ion batteries than does the well-crystallized K0.45MnO2, which is attributable to the greater surface area, higher structural and electrochemical stability, more homogeneous composite structure, and better charge-transfer characteristics of the amorphous materials. This result highlights the merit of the nanocrystalline and amorphous nature for optimizing the electrode performance of manganese oxide. The present solution-based redox reaction can provide a facile, economic, and scalable route for synthesizing efficient manganese

  17. Characterization of amorphous hydrogenated carbon films deposited by MFPUMST at different ratios of mixed gases

    Indian Academy of Sciences (India)

    Haiyang Dai; Changyong Zhan; Hui Jiang; Ningkang Huang

    2012-12-01

    Amorphous hydrogenated carbon films (-C:H) on -type (100) silicon wafers were prepared with a middle frequency pulsed unbalanced magnetron sputtering technique (MFPUMST) at different ratios of methane–argon gases. The band characteristics, mechanical properties as well as refractive index were measured by Raman spectra, X-ray photoelectron spectroscopy (XPS), nano-indentation tests and spectroscopic ellipsometry. It is found that the 3 fraction increases with increasing Ar concentration in the range of 17–50%, and then decreases when Ar concentration exceeds 50%. The nano-indentation tests reveal that nano-hardness and elastic modulus of the films increase with increasing Ar concentration in the range of 17–50%, while decreases with increasing Ar concentration from 50% to 86%. The variations in the nano-hardness and the elastic modulus could be interpreted due to different 3 fractions in the prepared -C:H films. The variation of refractive index with wavelength have the same tendency for the -C:H films prepared at different Ar concentrations, they decrease with increasing wavelength from 600 to 1700 nm. For certain wavelengths within 600–1700 nm, refractive index has the highest value at the Ar concentration of 50%, and it is smaller at the Ar concentration of 86% than at 17%. The results given above indicate that ratio of mixed gases has a strong influence on bonding configuration and properties of -C:H films during deposition. The related mechanism is discussed in this paper.

  18. Eigenschaften amorpher transparenter leitfähiger Oxide (a-TCOs)

    OpenAIRE

    Körner, Wolfgang; Elsässer, Christian

    2013-01-01

    In this contribution the optical and electrical properties of amorphous transparent conductive oxides (a-TCOs) are analysed by means of atomistic material modelling. The investigation of model structures by computer simulations allows a deeper understanding of the physical phenomena. In the case of the a-TCOs deep energy levels in the electronic band structure, that reduce for example the optical transparency, can be linked to structural defects on the atomic scale. This allows a well-directe...

  19. Nanoporous nickel-copper-phosphorus amorphous alloy film for methanol electro-oxidation in alkaline medium

    International Nuclear Information System (INIS)

    Highlights: • Novel Ni-Cu-P amorphous alloy with nanoporous structure was fabricated by LSV etching. • Lower onset oxidation potential of methanol at NP-NiCuP than both S-NiCuP and NP-NiCu. • Superior activity and stability for methanol oxidation at the NP-NiCuP electrode. • Long lifetime of the NP-NiCuP electrode. - Abstract: Nanoporous Ni-Cu-P amorphous alloy (NP-NiCuP) and nanoporous Ni-Cu crystalline alloy (NP-NiCu) are prepared by the linear sweep voltammetry (LSV) etching of copper from the electroless Ni-Cu-P and Ni-Cu alloy coatings, respectively. The results of X-ray diffraction (XRD) analysis show that the nanoporous Ni-Cu-P alloy is amorphous structure. The scanning electron microscopy (SEM) analysis demonstrates the NP-NiCuP shows a 3-D bi-continuous porous structure with the pore size of 150–200 nm and the ligament size of around 100 nm. Electrochemical performances are measured by cyclic voltammetry (CV) and chronoamperometry (CA). The results prove that the NP-NiCuP electrode exhibits higher the proton diffusion coefficient (D0) of Ni(OH)2 and surface coverage (Γ*) of the redox species than those on smooth electroless Ni-Cu-P amorphous alloy (S-NiCuP) and NP-NiCu electrodes in alkaline solution obviously. Moreover, electro-oxidation of methanol suggests that the NP-NiCuP electrode holds higher anodic current density and lower onset potential than the S-NiCuP and NP-NiCu electrodes. Finally, the NP-NiCuP electrode has stable redox behavior and superior catalytic stability for methanol oxidation

  20. Drain bias effect on the instability of amorphous indium gallium zinc oxide thin film transistor

    International Nuclear Information System (INIS)

    We fabricated amorphous indium gallium zinc oxide thin film transistors (TFTs) in a top gate structure on a glass substrate. We investigated the effect of drain bias on the instability of the device. Although the device showed highly stable characteristics under both positive and negative gate bias stress, it showed significant degradation in the transfer characteristics under drain bias stress. The degradation phenomena are somewhat similar to those of negative gate bias illumination stress (NBIS). In the case of NBIS, degradation mechanisms have been confused between two kinds of illustrations, one of which is hole trapping in the gate insulator and the other is an increase of electron density in the active layer. Our experimental results revealed that the degradation mechanism of drain bias stress is closer to the latter mechanism of NBIS in amorphous oxide TFTs. - Highlights: ► Drain bias also degrades amorphous oxide thin film transistors. ► Increase of electron density near the drain junction occurs under drain bias stress. ► Oxygen vacancies can be ionized through the impingement of fast electrons

  1. LOW TEMPERATURE OPTICAL PROPERTIES OF AMORPHOUS OXIDE NANOCLUSTERS IN POLYMETHYL METHACRYLATE MATRIX

    Institute of Scientific and Technical Information of China (English)

    V. V. VOLKOV; WANG ZHONG-LIN; Zou BING-SUO; XIE SI-SHEN

    2000-01-01

    We studied the temperature-dependent steady-state and time-resolved fluorescence properties of very small (1-2 nm) ZnO, CdO, and PbO amorphous nanoclusters prepared in AOT reverse micelles and imbedded in polymethyl methacrylate(PMMA) films. X-ray diffraction and electron diffraction and imaging indicate that these structures are amorphous. These amorphous oxide nanoclusters demonstrate similar structural, electronic, and optical properties. Properties of steady-state fluorescence spectra indicate the unique localization of electronic states due to the amorphous structure. ZnO and CdO show double-band fluorescence structure, which is due to the spin-orbital splitting, similar to Cu2O. Time-resolved fluorescence studies of the nanoclusters in the polymer reveal two lifetime components, as found in solution. The slow component reflects relaxation processes from band-tail states while the fast component may be related to high-lying extended states. The temperature dependence of fast fluorescence component reveals the presence of exciton hopping between anharmonic wells at temperatures higher than 200K. We correlate the barrier height between two wells formed around local atoms with the inter-atomic distance and bond ionicity.

  2. Degradation of electrochromic film of amorphous tungsten oxide after coloration

    Science.gov (United States)

    Luo, Zhongkuan

    1992-11-01

    The degradation of the electrochromic film of a-WO3 was investigated from the equilibrium state of different driving voltage and the time dependent emf was also obtained in an open or short circuit of zero volts. Based on the mechanism of activation and the principal of chemical reaction kinetics, the correct definition of electrochromic memory was made and a relation of memory was obtained. It was also found that at the initial time of natural bleaching, the change rate of proton concentration in the film was also obtained. According to the mechanism of electrochromic memory, it was indicated that in the open circuit case, the theoretical reaction of the change rate of electric potential was in good agrement with the experimental results, and furthermore, the reaction constant was determined with the experimental data. In the short circuit case, there exist two effects on degradation, the short circuit current caused by the backward emf, and the oxidation of the colored film. The experimental data shows that, in the short circuit case, the degradation strongly depends on the short circuit current and the effect of chemical reaction can be neglected.

  3. Review of recent developments in amorphous oxide semiconductor thin-film transistor devices

    Energy Technology Data Exchange (ETDEWEB)

    Park, Joon Seok; Maeng, Wan-Joo; Kim, Hyun-Suk [Display Device Laboratory, Samsung Advanced Institute of Technology (SAIT), Mt. 14-1, Nongseo-dong, Yongin, 446-712 (Korea, Republic of); Park, Jin-Seong, E-mail: jinseongpark@dankook.ac.kr [Department of Materials Science and Engineering, Dankook University, Mt. 29, Anseo-dong, Cheonan, 330-714 (Korea, Republic of)

    2012-01-01

    The present article is a review of the recent progress and major trends in the field of thin-film transistor (TFT) research involving the use of amorphous oxide semiconductors (AOS). First, an overview is provided on how electrical performance may be enhanced by the adoption of specific device structures and process schemes, the combination of various oxide semiconductor materials, and the appropriate selection of gate dielectrics and electrode metals in contact with the semiconductor. As metal oxide TFT devices are excellent candidates for switching or driving transistors in next generation active matrix liquid crystal displays (AMLCD) or active matrix organic light emitting diode (AMOLED) displays, the major parameters of interest in the electrical characteristics involve the field effect mobility ({mu}{sub FE}), threshold voltage (V{sub th}), and subthreshold swing (SS). A study of the stability of amorphous oxide TFT devices is presented next. Switching or driving transistors in AMLCD or AMOLED displays inevitably involves voltage bias or constant current stress upon prolonged operation, and in this regard many research groups have examined and proposed device degradation mechanisms under various stress conditions. The most recent studies involve stress experiments in the presence of visible light irradiating the semiconductor, and different degradation mechanisms have been proposed with respect to photon radiation. The last part of this review consists of a description of methods other than conventional vacuum deposition techniques regarding the formation of oxide semiconductor films, along with some potential application fields including flexible displays and information storage.

  4. Room-temperature fabrication of light-emitting thin films based on amorphous oxide semiconductor

    Directory of Open Access Journals (Sweden)

    Junghwan Kim

    2016-01-01

    Full Text Available We propose a light-emitting thin film using an amorphous oxide semiconductor (AOS because AOS has low defect density even fabricated at room temperature. Eu-doped amorphous In-Ga-Zn-O thin films fabricated at room temperature emitted intense red emission at 614 nm. It is achieved by precise control of oxygen pressure so as to suppress oxygen-deficiency/excess-related defects and free carriers. An electronic structure model is proposed, suggesting that non-radiative process is enhanced mainly by defects near the excited states. AOS would be a promising host for a thin film phosphor applicable to flexible displays as well as to light-emitting transistors.

  5. Visible-light-induced instability in amorphous metal-oxide based TFTs for transparent electronics

    Directory of Open Access Journals (Sweden)

    Tae-Jun Ha

    2014-10-01

    Full Text Available We investigate the origin of visible-light-induced instability in amorphous metal-oxide based thin film transistors (oxide-TFTs for transparent electronics by exploring the shift in threshold voltage (Vth. A large hysteresis window in amorphous indium-gallium-zinc-oxide (a-IGZO TFTs possessing large optical band-gap (≈3 eV was observed in a visible-light illuminated condition whereas no hysteresis window was shown in a dark measuring condition. We also report the instability caused by photo irradiation and prolonged gate bias stress in oxide-TFTs. Larger Vth shift was observed after photo-induced stress combined with a negative gate bias than the sum of that after only illumination stress and only negative gate bias stress. Such results can be explained by trapped charges at the interface of semiconductor/dielectric and/or in the gate dielectric which play a role in a screen effect on the electric field applied by gate voltage, for which we propose that the localized-states-assisted transitions by visible-light absorption can be responsible.

  6. Cathodo- and photoluminescence increase in amorphous hafnium oxide under annealing in oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Ivanova, E. V., E-mail: ivanova@mail.ioffe.ru; Zamoryanskaya, M. V. [Ioffe Physical Technical Institute (Russian Federation); Pustovarov, V. A. [Ural State Technical University (Russian Federation); Aliev, V. Sh.; Gritsenko, V. A. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Yelisseyev, A. P. [Russian Academy of Sciences, Institute of Geology and Mineralogy, Siberian Branch (Russian Federation)

    2015-04-15

    Cathodo- and photoluminescence of amorphous nonstoichiometric films of hafnium oxide are studied with the aim to verify the hypothesis that oxygen vacancies are responsible for the luminescence. To produce oxygen vacancies, hafnium oxide was enriched in surplus metal during synthesis. To reduce the oxygen concentration, the film was annealed in oxygen. A qualitative control of the oxygen concentration was carried out by the refractive index. In the initial, almost stoichiometric films we observed a 2.7-eV band in cathodoluminescence. Annealing in oxygen results in a considerable increase in its intensity, as well as in the appearance of new bands at 1.87, 2.14, 3.40, and 3.6 eV. The observed emission bands are supposed to be due to single oxygen vacancies and polyvacancies in hafnium oxide. The luminescence increase under annealing in an oxygen atmosphere may be a result of the emission quenching effect.

  7. Carrier transport and electronic structure in amorphous oxide semiconductor, a-InGaZnO4

    International Nuclear Information System (INIS)

    Carrier transport properties in amorphous oxide semiconductor InGaZnO4 (a-IGZO) thin films were investigated in detail using temperature dependence of Hall measurements. It was found that Hall mobility increased distinctly as carrier concentration increased. Unlikely conventional amorphous semiconductors such as a-Si/H, definite normal Hall voltage signals were observed on the films with carrier concentrations (N e)>1016 cm-3, and Hall mobilities as large as 15 cm2 (Vs)-1 were attained in the films with N e>1020 cm-3. When N e was less than 1019 cm-3, the temperature dependence of Hall mobility showed thermally-activated behavior in spite that carrier concentration was independent of temperature. While, it changed to almost degenerate conduction at N e>1018 cm-3. These behaviors are similar to those observed in single-crystalline IGZO, and are explained by percolation conduction through distributed potential barriers which are formed in the vicinity of the conduction band bottom due to the randomness of the amorphous structure. The effective mass of a-IGZO was estimated to be ∼0.34 m e (m e is the mass of free electron) from optical data, which is almost the same as that of crystalline IGZO (∼0.32 m e)

  8. Amorphous lanthanum lutetium oxide thin films as an alternative high-k gate dielectric

    OpenAIRE

    Lopes, J. M. J.; Roeckerath, M.; Schlom, D. G.; Heeg, T.; Rije, E.; Schubert, J; Mantl, S.; Afanas'ev, V.V.; Shamuilia, S.; Stesmans, A.; Jia, Y.

    2006-01-01

    Lanthanum lutetium oxide thin films were grown on (100) Si by pulsed laser deposition. Rutherford backscattering spectrometry, atomic force microscopy, x-ray diffraction, and x-ray reflectometry were employed to investigate the samples. The results indicate the growth of stoichiometric and smooth LaLuO3 films that remain amorphous up to 1000 degrees C. Internal photoemission and photoconductivity measurements show a band gap width of 5.2 +/- 0.1 eV and symmetrical conduction and valence band ...

  9. Low-temperature solution-processed amorphous indium tin oxide field-effect transistors.

    Science.gov (United States)

    Kim, Hyun Sung; Kim, Myung-Gil; Ha, Young-Geun; Kanatzidis, Mercouri G; Marks, Tobin J; Facchetti, Antonio

    2009-08-12

    Amorphous indium tin oxide (ITO)-based thin-film transistors (TFTs) were fabricated on various dielectrics [SiO(2) and self-assembled nanodielectrics (SANDs)] by spin-coating an ITO film precursor solution consisting of InCl(3) and SnCl(4) as the sources of In(3+) and Sn(4+), respectively, methoxyethanol (solvent), and ethanolamine (base). These films can be annealed at temperatures T(a) 0.2 cm(2) V(-1) s(-1), which is encouraging for processing on plastic substrates.

  10. Dry Etching Characteristics of Amorphous Indium-Gallium-Zinc-Oxide Thin Films

    Institute of Scientific and Technical Information of China (English)

    郑艳彬; 李光; 王文龙; 李秀昌; 姜志刚

    2012-01-01

    Amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) backplane technology is the best candidate for flat panel displays (FPDs). In this paper, a-IGZO TFT structures are described. The effects of etch parameters (rf power, dc-bias voltage and gas pressure) on the etch rate and etch profile are discussed. Three kinds of gas mixtures are compared in the dry etching process of a-IGZO thin films. Lastly, three problems are pointed out that need to be addressed in the dry etching process of a-IGZO TFTs.

  11. Interface Study on Amorphous Indium Gallium Zinc Oxide Thin Film Transistors Using High-k Gate Dielectric Materials

    OpenAIRE

    Yu-Hsien Lin; Jay-Chi Chou

    2015-01-01

    We investigated amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFTs) using different high-k gate dielectric materials such as silicon nitride (Si3N4) and aluminum oxide (Al2O3) at low temperature process (

  12. Amorphous iron–chromium oxide nanoparticles with long-term stability

    Energy Technology Data Exchange (ETDEWEB)

    Iacob, Mihail [“Petru Poni” Institute of Macromolecular Chemistry, Iasi 700487 (Romania); Institute of Chemistry of ASM, Academiei str. 3, Chisinau 2028, Republic of Moldova (Moldova, Republic of); Cazacu, Maria, E-mail: mcazacu@icmpp.ro [“Petru Poni” Institute of Macromolecular Chemistry, Iasi 700487 (Romania); Turta, Constantin [Institute of Chemistry of ASM, Academiei str. 3, Chisinau 2028, Republic of Moldova (Moldova, Republic of); Doroftei, Florica [“Petru Poni” Institute of Macromolecular Chemistry, Iasi 700487 (Romania); Botko, Martin; Čižmár, Erik; Zeleňáková, Adriana; Feher, Alexander [Institute of Physics, Faculty of Science, P.J. Šafárik University, Park Angelinum 9, SK-04154 Košice (Slovakia)

    2015-05-15

    Highlights: • Fe–Cr oxide nanoparticles with pre-established metals ratio were obtained. • The amorphous state and its long-term stability were highlighted by X-ray diffraction. • The average diameter of dried nanoparticles was 3.5 nm, as was estimated by TEM, AFM. • In hexane dispersion, nanoparticles with diameter in the range 2.33–4.85 nm were found. • Superparamagnetic state of NPs co-exists with diamagnetism of the organic layer. - Abstract: Iron–chromium nanoparticles (NPs) were obtained through the thermal decomposition of μ{sub 3}-oxo heterotrinuclear (FeCr{sub 2}O) acetate in the presence of sunflower oil and dodecylamine (DA) as surfactants. The average diameter of the NPs was 3.5 nm, as estimated on the basis of transmission electron microscopy and atomic force microscopy images. Both techniques revealed the formation of roughly approximated spheres with some irregularities and agglomerations in larger spherical assemblies of 50–100 nm. In hexane, NPs with diameters in the 2.33–4.85 nm range are individually dispersed, as emphasized by dynamic light scattering measurements. The amorphous nature of the product was emphasized by X-ray powder diffraction. The study of the magnetic properties shows the presence of superparamagnetic state of iron–chromium oxide NPs and the diamagnetic contribution from DA layer forming a shell of NPs.

  13. Optimizing amorphous indium zinc oxide film growth for low residual stress and high electrical conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Mukesh [Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO 80401 (United States); Sigdel, A.K. [Department of Physics and Astronomy, University of Denver, Denver, CO 80208 (United States); National Center for Photovoltaics, National Renewal Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401 (United States); Gennett, T.; Berry, J.J.; Perkins, J.D.; Ginley, D.S. [National Center for Photovoltaics, National Renewal Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401 (United States); Packard, C.E., E-mail: cpackard@mines.edu [Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO 80401 (United States); National Center for Photovoltaics, National Renewal Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401 (United States)

    2013-10-15

    With recent advances in flexible electronics, there is a growing need for transparent conductors with optimum conductivity tailored to the application and nearly zero residual stress to ensure mechanical reliability. Within amorphous transparent conducting oxide (TCO) systems, a variety of sputter growth parameters have been shown to separately impact film stress and optoelectronic properties due to the complex nature of the deposition process. We apply a statistical design of experiments (DOE) approach to identify growth parameter–material property relationships in amorphous indium zinc oxide (a-IZO) thin films and observed large, compressive residual stresses in films grown under conditions typically used for the deposition of highly conductive samples. Power, growth pressure, oxygen partial pressure, and RF power ratio (RF/(RF + DC)) were varied according to a full-factorial test matrix and each film was characterized. The resulting regression model and analysis of variance (ANOVA) revealed significant contributions to the residual stress from individual growth parameters as well as interactions of different growth parameters, but no conditions were found within the initial growth space that simultaneously produced low residual stress and high electrical conductivity. Extrapolation of the model results to lower oxygen partial pressures, combined with prior knowledge of conductivity–growth parameter relationships in the IZO system, allowed the selection of two promising growth conditions that were both empirically verified to achieve nearly zero residual stress and electrical conductivities >1480 S/cm. This work shows that a-IZO can be simultaneously optimized for high conductivity and low residual stress.

  14. Effect of SR irradiation on crystallization of amorphous tin oxide film

    CERN Document Server

    Kimura, Y; Hanamoto, K; Sasaki, M; Kimura, S; Nakada, Tatsuya; Nakayama, Y; Kaito, C

    2001-01-01

    In order to see the effect of SR irradiation on crystal growth, crystallization of tin oxide films has been performed in vacuum under SR irradiation. A thin amorphous tin oxide film 50 nm thick was prepared on the carbon substrate by vacuum evaporation of SnO sub 2 power. A SnO crystal appeared between 450-500 deg. C upon vacuum heating, with a preferred orientation of (0 0 1). By SR irradiation using a cylindrical mirror for 20 s, the SnO crystal appeared with the preferred orientation of (1 1 1). The crystal with the crystallographic shear structure was grown by SR irradiation. This growth under a SR beam is discussed in terms of SR beam excitation of lone-pair electrons seen in the SnO crystal structure.

  15. High-stability transparent amorphous oxide TFT with a silicon-doped back-channel layer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyoung-Rae; Park, Jea-Gun [Hanyang University, Seoul (Korea, Republic of)

    2014-10-15

    We significantly reduced various electrical instabilities of amorphous indium gallium zinc oxide thin-film transistors (TFTs) by using the co-deposition of silicon on an a-IGZO back channel. This process showed improved stability of the threshold voltage (V{sub th}) under high temperature and humidity and negative gate-bias illumination stress (NBIS) without any reduction of IDS. The enhanced stability was achieved with silicon, which has higher metal-oxide bonding strengths than gallium does. Additionally, SiO{sub x} distributed on the a-IGZO surface reduced the adsorption and the desorption of H{sub 2}O and O{sub 2}. This process is applicable to the TFT manufacturing process with a variable sputtering target.

  16. Microstructural study of oxidation of carbon-rich amorphous boron carbide coating

    Institute of Scientific and Technical Information of China (English)

    Bin ZENG; Zu-de FENG; Si-wei LI; Yong-sheng LIU

    2008-01-01

    Carbon-rich amorphous boron carbide (BxC) coatings were annealed at 400℃, 700℃, 1000℃ and 1200℃ for 2 h in air atmosphere. The microstructure and composition of the as-deposited and annealed coat-ings were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-Raman spectro-scopy and energy dispersive X-ray spectroscopy (EDS). All of the post-anneal characterizations demonstrated the ability of carbon-rich BxC coatings to protect the graphite substrate against oxidation. Different oxidation modes of the coatings were found at low temperature (400℃), moderate temperature (700℃) and high temper-ature (1000℃ and 1200℃). Finally, the feasibility of the application of carbon-rich BxC instead of pyrolytic car-bon (PyC) as a fiber/matrix interlayer in ceramics-matrix composites (CMCs) is discussed here.

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

    Directory of Open Access Journals (Sweden)

    M. Morales-Masis

    2014-09-01

    Full Text Available Improving the conductivity of earth-abundant transparent conductive oxides (TCOs remains an important challenge that will facilitate the replacement of indium-based TCOs. Here, we show that a hydrogen (H2-plasma post-deposition treatment improves the conductivity of amorphous aluminum-doped zinc tin oxide while retaining its low optical absorption. We found that the H2-plasma treatment performed at a substrate temperature of 50 °C reduces the resistivity of the films by 57% and increases the absorptance by only 2%. Additionally, the low substrate temperature delays the known formation of tin particles with the plasma and it allows the application of the process to temperature-sensitive substrates.

  18. Effect of hydrogen on dynamic charge transport in amorphous oxide thin film transistors

    Science.gov (United States)

    Kim, Taeho; Nam, Yunyong; Hur, Ji-Hyun; Park, Sang-Hee Ko; Jeon, Sanghun

    2016-08-01

    Hydrogen in zinc oxide based semiconductors functions as a donor or a defect de-activator depending on its concentration, greatly affecting the device characteristics of oxide thin-film transistors (TFTs). Thus, controlling the hydrogen concentration in oxide semiconductors is very important for achieving high mobility and minimizing device instability. In this study, we investigated the charge transport dynamics of the amorphous semiconductor InGaZnO at various hydrogen concentrations as a function of the deposition temperature of the gate insulator. To examine the nature of dynamic charge trapping, we employed short-pulse current‑voltage and transient current‑time measurements. Among various examined oxide devices, that with a high hydrogen concentration exhibits the best performance characteristics, such as high saturation mobility (10.9 cm2 v‑1 s‑1), low subthreshold slope (0.12 V/dec), and negligible hysteresis, which stem from low defect densities and negligible transient charge trapping. Our finding indicates that hydrogen atoms effectively passivate the defects in subgap states of the bulk semiconductor, minimizing the mobility degradation and threshold voltage instability. This study indicates that hydrogen plays a useful role in TFTs by improving the device performance and stability.

  19. Effect of hydrogen on dynamic charge transport in amorphous oxide thin film transistors.

    Science.gov (United States)

    Kim, Taeho; Nam, Yunyong; Hur, Ji-Hyun; Park, Sang-Hee Ko; Jeon, Sanghun

    2016-08-12

    Hydrogen in zinc oxide based semiconductors functions as a donor or a defect de-activator depending on its concentration, greatly affecting the device characteristics of oxide thin-film transistors (TFTs). Thus, controlling the hydrogen concentration in oxide semiconductors is very important for achieving high mobility and minimizing device instability. In this study, we investigated the charge transport dynamics of the amorphous semiconductor InGaZnO at various hydrogen concentrations as a function of the deposition temperature of the gate insulator. To examine the nature of dynamic charge trapping, we employed short-pulse current-voltage and transient current-time measurements. Among various examined oxide devices, that with a high hydrogen concentration exhibits the best performance characteristics, such as high saturation mobility (10.9 cm(2) v(-1) s(-1)), low subthreshold slope (0.12 V/dec), and negligible hysteresis, which stem from low defect densities and negligible transient charge trapping. Our finding indicates that hydrogen atoms effectively passivate the defects in subgap states of the bulk semiconductor, minimizing the mobility degradation and threshold voltage instability. This study indicates that hydrogen plays a useful role in TFTs by improving the device performance and stability. PMID:27363543

  20. Optical and electrical studies of cerium mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Sherly, T. R., E-mail: trsherly@gmail.com [Post Graduate Department of Physics, Sanathana Dharma College, Alappuzha, Kerala (India); Raveendran, R. [Nanoscience Research Laboratory, Sree Narayana College, Kollam, Kerala 691001 (India)

    2014-10-15

    The fast development in nanotechnology makes enthusiastic interest in developing nanomaterials having tailor made properties. Cerium mixed oxide materials have received great attention due to their UV absorption property, high reactivity, stability at high temperature, good electrical property etc and these materials find wide applications in solid oxide fuel cells, solar control films, cosmetics, display units, gas sensors etc. In this study cerium mixed oxide compounds were prepared by co-precipitation method. All the samples were doped with Zn (II) and Fe (II). Preliminary characterizations such as XRD, SEM / EDS, TEM were done. UV - Vis, Diffuse reflectance, PL, FT-IR, Raman and ac conductivity studies of the samples were performed.

  1. Tailoring the optical and hydrophobic property of zinc oxide nanorod by coating with amorphous graphene

    Science.gov (United States)

    Pahari, D.; Das, N. S.; Das, B.; Chattopadhyay, K. K.; Banerjee, D.

    2016-09-01

    Zinc oxide (ZnO) nanorods were synthesized at room temperature on potassium permanganate activated silicon and glass substrate by simple chemical method using zinc acetate as precursor. To modify the surface energy of the as prepared ZnO thin films the samples were coated with amorphous graphene (a-G) synthesized by un-zipping of chemically synthesized amorphous carbon nanotubes (a-CNTs). All the pure and coated samples were characterized by x-ray diffraction, field emission scanning electron microscope, Raman spectroscopy, and Fourier transformed infrared spectroscopy. The roughness analysis of the as prepared samples was done by atomic force microscopic analysis. The detail optical properties of all the samples were studied with the help of a UV-Visible spectrophotometer. The surface energy of the as prepared pure and coated samples was calculated by measuring the contact angle of two different liquids. It is seen that the water repellence of ZnO nanorods got increased after they are being coated with a-Gs. Also even after UV irradiation the contact angle remain same unlike the case for the uncoated sample where the contact angle gets decreased significantly after UV irradiation. Existing Cassie-Wenzel model has been employed along with the Owen's approach to determine the different components of surface energy.

  2. High thermal stability of the amorphous oxide in Ti44.5Cu44.5Zr7Be4 metallic glass

    Directory of Open Access Journals (Sweden)

    Sung Hyun Park

    2015-11-01

    Full Text Available The oxidation behavior of Ti44.5Cu44.5Zr7Be4 metallic glass has been investigated. The oxide layer with a fully amorphous structure forms when heated up to the SCL temperature region, indicating that the presence of Be in the oxide layer improves the thermal stability of the amorphous oxide. The amorphous oxide is stable even when heated above the crystallization onset temperature. The thickness of the amorphous oxide layer reaches to ∼160 nm when heated up to 773 K. The oxide layer grows in both inward and outward directions, leaving Cu-enriched crystalline particles at the middle section of the oxide layer.

  3. Mixed oxide fuel for water cooled reactors

    International Nuclear Information System (INIS)

    The problems connected with introduction of plutonium extracted from spent fuels of operating NPPs into water cooled reactor fuel cycle are considered. The trends in formation of the World market of mixed fuel are illustrated taking as examples Great Britain and Japan

  4. Foaming of amorphous drug delivery systems prepared by hot melt mixing and extrusion

    Science.gov (United States)

    Terife, Graciela

    Currently there is considerable interest from both academe and pharmaceutical industry in exploring foaming processes and their products in drug delivery applications. However, there is still little knowledge of the impact of the morphology of the foamed structures on the performance of drug products in spite of some publications in this area. Therefore, the main objective of this dissertation is to gain a fundamental understanding of the correlation between foam morphology and performance of amorphous drug delivery systems, which are comprised of an Active Pharmaceutical Ingredient (API) and Polymer excipient. The Hot Melt Extrusion (HME) process is used to compound the following API / polymer binary systems: Indomethacin (INM) with SoluplusRTM (PVCap-PVAc-PEG); Carbamazepine (CBZ) with PVCap-PVAc-PEG; and INM with EudragitRTM EPO. Comprehensive characterization of these binary systems carried out by combining Differential Scanning Calorimetry, Fourier Transform Infrared spectroscopy, X-Ray Diffraction, and Scanning Electron Microscopy, shows that in all HME-prepared and foamed samples the APIs are amorphous and dissolved in the polymer excipients. The most important contributions of this dissertation can be grouped into three areas: (a) an understanding of the mechanisms by which foamed dosage forms can lead to faster API release, as well as the key morphological aspects of the cellular structures to achieve this, (b) an understanding of the correlation between the mechanism controlling the release of an API from an amorphous dosage and the enhancement in its release rate upon foaming, and (c) an understanding of the impact of the morphology of the cellular structures in the milling efficiency of HME products and the dissolution performance of the particles produced. In the first area, foamed amorphous solid solutions with three different morphologies are produced through the batch foaming process. A strong correlation between foam morphology and the enhancement

  5. Pulverizing and mixing method and device for uranium/plutonium mixed oxide powder

    International Nuclear Information System (INIS)

    The present invention concerns a uranium/plutonium mixed oxide fuel (MOX) and it provides a device for uniformly mixing PuO2 powder and UO2 powder. Namely, a vessel contains a uranium/plutonium mixed oxide powder at a thickness of lower than a critical level. An upper disk and a lower disk are opposed to each other at a predetermined distance in the inside of the vessel. Each of the disks has crusher teeth in an annular shape with a different diameter. An oxide powder is supplied to the vessel, and the upper disk and the lower disk are rotated at a high speed in the direction opposite to each other. As is described above, since the oxide powder is mixed under pulverization while being dispersed by the method and the device of the present invention, the powder is mixed at a good homogeneity. Since the oxide powder is pulverized and mixed in the vessel, the operation can be preceded in a completely sealed state. Since the operation can be conducted continuously, the processing performance can be improved. Since the thickness of the powder in the inside of the vessel and the thickness thereof at a discharge port are at a subcritical level, control for the critical safety is facilitated. (I.S.)

  6. Size modulation of nanocrystalline silicon embedded in amorphous silicon oxide by Cat-CVD

    International Nuclear Information System (INIS)

    Different issues related to controlling size of nanocrystalline silicon (nc-Si) embedded in hydrogenated amorphous silicon oxide (a-SiOx:H) deposited by catalytic chemical vapor deposition (Cat-CVD) have been reported. Films were deposited using tantalum (Ta) and tungsten (W) filaments and it is observed that films deposited using tantalum filament resulted in good control on the properties. The parameters which can affect the size of nc-Si domains have been studied which include hydrogen flow rate, catalyst and substrate temperatures. The deposited samples are characterized by X-ray diffraction, HRTEM and micro-Raman spectroscopy, for determining the size of the deposited nc-Si. The crystallite formation starts for Ta-catalyst around the temperature of 1700 oC.

  7. A novel composite material based on antimony(III) oxide and amorphous silica

    Energy Technology Data Exchange (ETDEWEB)

    Zemnukhova, Ludmila A. [Institute of Chemistry, Far-Eastern Branch, Russian Academy of Sciences, 690022 Vladivostok (Russian Federation); Panasenko, Alexander E., E-mail: panasenko@ich.dvo.ru [Institute of Chemistry, Far-Eastern Branch, Russian Academy of Sciences, 690022 Vladivostok (Russian Federation)

    2013-05-01

    The composite material nSb₂O₃·mSiO₂·xH₂O was prepared by hydrolysis of SbCl₃ and Na₂SiO₃ in an aqueous medium. It has been shown that the composition of the material is influenced by the ratio of the initial components and the acidity of the reaction medium. The morphology of the material particles and its specific surface area have been determined. The thermal and optic properties were also investigated. - Graphical abstract: Novel composite material containing amorphous silica and crystal antimony(III) oxide has been synthesized by hydrolysis of SbCl₃ and Na₂SiO₃ in an aqueous medium. Highlights: • The composite material nSb₂O₃·mSiO₂·xH₂O was prepared in an aqueous medium. • The composition of the material is controllable by a synthesis conditions. • The morphology of the material and its optic properties have been determined.

  8. Numerical simulation of offset-drain amorphous oxide-based thin-film transistors

    Science.gov (United States)

    Jeong, Jaewook

    2016-11-01

    In this study, we analyzed the electrical characteristics of amorphous indium–gallium–zinc-oxide (a-IGZO) thin-film transistors (TFTs) with an offset-drain structure by technology computer aided design (TCAD) simulation. When operating in a linear region, an enhancement-type TFT shows poor field-effect mobility because most conduction electrons are trapped in acceptor-like defects in an offset region when the offset length (L off) exceeds 0.5 µm, whereas a depletion-type TFT shows superior field-effect mobility owing to the high free electron density in the offset region compared with the trapped electron density. When operating in the saturation region, both types of TFTs show good field-effect mobility comparable to that of a reference TFT with a large gate overlap. The underlying physics of the depletion and enhancement types of offset-drain TFTs are systematically analyzed.

  9. Performance enhancement of amorphous indium-zinc-oxide thin film transistors by microwave annealing

    Science.gov (United States)

    Xu, Rui; He, Jian; Li, Wei; Paine, David C.

    2015-12-01

    The effect of microwave annealing on the field effect mobility and threshold voltage of amorphous indium zinc oxide (a-IZO) thin film transistors (TFTs) is reported. A control device with traditional hotplate annealing at 200 °C for 1 h was applied for comparison. The results show that both microwave annealing and low-temperature hotplate annealing increase the field effect mobility from 12.3 cm2/V s in as-deposited state to ∼19 cm2/V s in annealed state. However, the negative shift in threshold voltage with microwave annealing (from 0.23 V to -2.86 V) is smaller than that with low-temperature hotplate annealing (to -9 V). A mechanism related with the electrical properties of a-IZO material is proposed. This rapid low-temperature annealing technology makes a-IZO TFTs promising for use in flexible, transparent electronics.

  10. Mesostructured amorphous manganese oxides: facile synthesis and highly durable elimination of low-concentration NO at room temperature in air.

    Science.gov (United States)

    Du, Yanyan; Hua, Zile; Huang, Weimin; Wu, Meiying; Wang, Min; Wang, Jin; Cui, Xiangzhi; Zhang, Lingxia; Chen, Hangrong; Shi, Jianlin

    2015-04-01

    At a high space velocity of 120 000 mL g(-1) h(-1) and a relative humidity of 50-90%, 98% removal of 10 ppm NO has been achieved for over 237 h and no sign of deactivation was observed with mesostructured amorphous manganese oxides (AMO), due to the prevention of the catalyst active sites from deactivation. PMID:25728967

  11. Temperature-dependent minority carrier lifetime of crystalline silicon wafers passivated by high quality amorphous silicon oxide

    Science.gov (United States)

    Inaba, Masahiro; Todoroki, Soichiro; Nakada, Kazuyoshi; Miyajima, Shinsuke

    2016-04-01

    We investigated the effects of annealing on the temperature-dependent minority carrier lifetime of a crystalline silicon wafer passivated by hydrogenated amorphous silicon oxide. The annealing significantly affects the lifetime and its temperature dependence. Our device simulations clearly indicate that valence band offset significantly affects the temperature dependence. We also found a slight increase in the interface defect density after annealing.

  12. Low-temperature formation of source–drain contacts in self-aligned amorphous oxide thin-film transistors

    NARCIS (Netherlands)

    Nag, M.; Muller, R.; Steudel, S.; Smout, S.; Bhoolokam, A.; Myny, K.; Schols, S.; Genoe, J.; Cobb, B.; Kumar, A.; Gelinck, G.; Fukui, Y.; Groeseneken, G.; Heremans, P.

    2015-01-01

    We demonstrated self-aligned amorphous-Indium-Gallium-Zinc-Oxide (a-IGZO) thin-film transistors (TFTs) where the source–drain (S/D) regions were made conductive via chemical reduction of the a-IGZO via metallic calcium (Ca). Due to the higher chemical reactivity of Ca, the process can be operated at

  13. The synthesis and arrested oxidation of amorphous cobalt nanoparticles using DMSO as a functional solvent

    International Nuclear Information System (INIS)

    Magnetic nanoparticles exhibit a strong tendency to become overly oxidized and unstable during synthesis, ultimately leading to nanoparticle agglomeration and degradation. Capping agents can be used during nanoparticle synthesis to provide particle surface coverage and to improve nanoparticle dispersibility in solution, while preventing excessive oxidation and agglomeration. This paper presents a technique to synthesize amorphous 3.7 ± 1.5 nm cobalt (Co) nanoparticles using dimethyl sulfoxide (DMSO) to function as both the stabilizing agent and the solvent for Co nanoparticles via a quick, solvent-based reduction of Co2+ with NaBH4 in a DMSO solvent. UV–visible spectroscopy analysis was used to determine the minimum amount of reducing agent needed to produce Co nanoparticles so as to limit the waste of reagents. TEM and SEM imaging were used to study the morphology of the Co nanoparticles from the DMSO dispersion and of the Co nanoparticle powder. FT-IR was used to elucidate the nature of the interaction between the Co nanoparticle surface and DMSO. Furthermore, SEM–EDS elemental mapping was used to determine the composition and surface properties of the Co nanoparticles. This synthesis method demonstrates that Co nanoparticles can be successfully synthesized by simply using DMSO as a functional solvent, thereby avoiding excessive oxidation and agglomeration in solution

  14. Carrier Transport at Metal/Amorphous Hafnium-Indium-Zinc Oxide Interfaces.

    Science.gov (United States)

    Kim, Seoungjun; Gil, Youngun; Choi, Youngran; Kim, Kyoung-Kook; Yun, Hyung Joong; Son, Byoungchul; Choi, Chel-Jong; Kim, Hyunsoo

    2015-10-14

    In this paper, the carrier transport mechanism at the metal/amorphous hafnium-indium-zinc oxide (a-HIZO) interface was investigated. The contact properties were found to be predominantly affected by the degree of interfacial reaction between the metals and a-HIZO; that is, a higher tendency to form metal oxide phases leads to excellent Ohmic contact via tunneling, which is associated with the generated donor-like oxygen vacancies. In this case, the Schottky-Mott theory is not applicable. Meanwhile, metals that do not form interfacial metal oxide, such as Pd, follow the Schottky-Mott theory, which results in rectifying Schottky behavior. The Schottky characteristics of the Pd contact to a-HIZO can be explained in terms of the barrier inhomogeneity model, which yields a mean barrier height of 1.40 eV and a standard deviation of 0.14 eV. The work function of a-HIZO could therefore be estimated as 3.7 eV, which is in good agreement with the ultraviolet photoelectron spectroscopy (3.68 eV). Our findings will be useful for establishing a strategy to form Ohmic or Schottky contacts to a-HIZO films, which will be essential for fabricating reliable high-performance electronic devices. PMID:26411354

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

    Science.gov (United States)

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

    2016-05-01

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

  16. A tunable amorphous p-type ternary oxide system: The highly mismatched alloy of copper tin oxide

    Energy Technology Data Exchange (ETDEWEB)

    Isherwood, Patrick J. M., E-mail: P.J.M.Isherwood@lboro.ac.uk; Walls, John M. [CREST, School of Electronic, Electrical and Systems Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom); Butler, Keith T.; Walsh, Aron [Centre for Sustainable Technologies and Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom)

    2015-09-14

    The approach of combining two mismatched materials to form an amorphous alloy was used to synthesise ternary oxides of CuO and SnO{sub 2}. These materials were analysed across a range of compositions, and the electronic structure was modelled using density functional theory. In contrast to the gradual reduction in optical band gap, the films show a sharp reduction in both transparency and electrical resistivity with copper contents greater than 50%. Simulations indicate that this change is caused by a transition from a dominant Sn 5s to Cu 3d contribution to the upper valence band. A corresponding decrease in energetic disorder results in increased charge percolation pathways: a “compositional mobility edge.” Contributions from Cu(II) sub band-gap states are responsible for the reduction in optical transparency.

  17. An amorphous phase formation at palladium / silicon oxide (Pd/SiO{sub x}) interface through electron irradiation - electronic excitation process

    Energy Technology Data Exchange (ETDEWEB)

    Nagase, Takeshi, E-mail: t-nagase@uhvem.osaka-u.ac.jp [Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1, Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1, Yamada-Oka, Suita, Osaka 565-0871 (Japan); Yamashita, Ryo; Yabuuchi, Atsushi [Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1, Yamada-Oka, Suita, Osaka 565-0871 (Japan); Lee, Jung-Goo [Powder & Ceramics Division, Korea Institute of Materials Science, 66 Sangnam-dong, Changwon, Kyungsangnam-Do 641-101 (Korea, Republic of)

    2015-11-15

    A Pd-Si amorphous phase was formed at a palladium/silicon oxide (Pd/SiO{sub x}) interface at room temperature by electron irradiation at acceleration voltages ranging between 25 kV and 200 kV. Solid-state amorphization was stimulated without the electron knock-on effects. The total dose required for the solid-state amorphization decreases with decreasing acceleration voltage. This is the first report on electron irradiation induced metallic amorphous formation caused by the electronic excitation at metal/silicon oxide interface.

  18. Chemical interaction of Ce-Fe mixed oxides for methane selective oxidation

    Institute of Scientific and Technical Information of China (English)

    祝星; 杜云鹏; 王华; 魏永刚; 李孔斋; 孙令玥

    2014-01-01

    Chemical interaction of Ce-Fe mixed oxides was investigated in methane selective oxidation via methane temperature pro-grammed reduction and methane isothermal reaction tests over Ce-Fe oxygen carriers. In methane temperature programmed reduction test, Ce-Fe oxide behaved complete oxidation at the lower temperature and selective oxidation at higher temperatures. Ce-Fe mixed oxides with the Fe content in the range of 0.1-0.5 was able to produce syngas with high selectivity in high-temperature range (800-900 °C), and a higher Fe amount over 0.5 seemed to depress the CO formation. In isothermal reaction, complete oxidation oc-curred at beginning following with selective oxidation later. Ce1-xFexO2-δ oxygen carriers (x≤0.5) were proved to be suitable for the selective oxidation of methane. Ce-Fe mixed oxides had the well-pleasing reducibility with high oxygen releasing rate and CO selec-tivity due to the interaction between Ce and Fe species. Strong chemical interaction of Ce-Fe mixed oxides originated from both Fe* activated CeO2 and Ce3+ activated iron oxides (FeOm), and those chemical interaction greatly enhanced the oxygen mobility and se-lectivity.

  19. Microstructure and oxygen evolution of Fe-Ce mixed oxides by redox treatment

    Science.gov (United States)

    Li, Kongzhai; Haneda, Masaaki; Ning, Peihong; Wang, Hua; Ozawa, Masakuni

    2014-01-01

    The relationship between structure and reduction/redox properties of Fe-Ce mixed oxides with a Fe content of 5, 10, 20 or 30 mol%, prepared by a coprecipitation method, were investigated by XRD, Raman, TEM, TPR and TPO techniques. It is found that all the iron ions can be incorporated into the ceria lattice to form a solid solution for the FeCe 5 (Fe 5%) sample, but amorphous or crystal Fe2O3 particles were found to be present on the Fe-Ce oxide samples with higher the iron content. The reducibility of single solid solution was much better than the pure CeO2, and the appearance of dispersed Fe2O3 particles improved the surface reducibility of materials. The iron ions incorporated into the CeO2 lattice accelerated the oxygen release from bulk to surface, and surface Fe2O3 particles in close contact to CeO2 acted as a catalyst for the reaction between solid solution and hydrogen. The microstructure of exposed Fe2O3 with Ce-Fe-O solid solution allows the Fe-Ce mixed oxides to own good reducibility and high OSC, which also counteracts the deactivation of the reducibility resulting from the sintering of materials in the redox cycling.

  20. Interaction between uranium-plutonium mixed oxide and zircaloy-2

    International Nuclear Information System (INIS)

    Currently there is considerable interest in the utilisation of zircaloy-clad mixed U-Pu oxide as fuel for thermal reactors. Thermodynamic calculations predict that zircaloy can easily reduce PuO2 to Pu2O3 and this has been confirmed experimentally. However, mixed oxide is expected to behave differently in this respect. The present investigation is an attempt to study, out-of-pile, the extent of chemical reaction between U-Pu oxide and zircaloy-2. Although the thermal reactor fuels generally contain a low percentage of PuO2(2), a mixed oxide containing 20%PuO2 was chosen for this study to enhance the possibility of reaction. It was assumed that if no reaction takes place with this composition none would occur with those containing less PuO2. With a view to keeping the reactants in close proximity, the experiments were carried out on composite pellets made from powdered sintered mixed oxide and zircaloy filings. Some composite pellets of pure PuO2 and zircaloy were also included in the study as an extreme case of reactivity. (Auth.)

  1. Amorphous cobalt potassium phosphate microclusters as efficient photoelectrochemical water oxidation catalyst

    Science.gov (United States)

    Zhang, Ye; Zhao, Chunsong; Dai, Xuezeng; Lin, Hong; Cui, Bai; Li, Jianbao

    2013-12-01

    A novel amorphous cobalt potassium phosphate hydrate compound (KCoPO4·H2O) is identified to be active photocatalyst for oxygen evolution reaction (OER) to facilitate hydrogen generation from water photolysis. It has been synthesized through a facile and cost-effective solution-based precipitation method using earth-abundant materials. Its highly porous structure and large surface areas are found to be responsible for the excellent electrochemical performance featuring a low OER onset at ˜550 mVSCE and high current density in alkaline condition. Unlike traditional cobalt-based spinel oxides (Co3O4, NiCo2O4) and phosphate (Co-Pi, Co(PO3)2) electrocatalysts, with proper energy band alignment for light-assisted water oxidation, cobalt potassium phosphate hydrate also exhibits robust visible-light response, generating a photocurrent density of ˜200 μA cm-2 at 0.7 VSCE. This catalyst could thus be considered as a promising candidate to perform photoelectrochemical water splitting.

  2. Water oxidation catalysis: an amorphous quaternary Ba-Sr-Co-Fe oxide as a promising electrocatalyst for the oxygen-evolution reaction.

    Science.gov (United States)

    Zhang, Cuijuan; Berlinguette, Curtis P; Trudel, Simon

    2016-01-25

    We present an amorphous quaternary Ba-Sr-Co-Fe oxide (a-BSCF) with a specific stoichiometry, readily fabricated via a photochemical decomposition method. a-BSCF demonstrates high catalytic activity towards the oxygen-evolution reaction (OER). PMID:26659269

  3. Photochemical oxidation: A solution for the mixed waste dilemma

    Energy Technology Data Exchange (ETDEWEB)

    Prellberg, J.W.; Thornton, L.M.; Cheuvront, D.A. [Vulcan Peroxidation Systems, Inc., Tucson, AZ (United States)] [and others

    1995-12-31

    Numerous technologies are available to remove organic contamination from water or wastewater. A variety of techniques also exist that are used to neutralize radioactive waste. However, few technologies can satisfactorily address the treatment of mixed organic/radioactive waste without creating unacceptable secondary waste products or resulting in extremely high treatment costs. An innovative solution to the mixed waste problem is on-site photochemical oxidation. Liquid-phase photochemical oxidation has a long- standing history of successful application to the destruction of organic compounds. By using photochemical oxidation, the organic contaminants are destroyed on-site leaving the water, with radionuclides, that can be reused or disposed of as appropriate. This technology offers advantages that include zero air emissions, no solid or liquid waste formation, and relatively low treatment cost. Discussion of the photochemical process will be described, and several case histories from recent design testing, including cost analyses for the resulting full-scale installations, will be presented as examples.

  4. Heterogeneous Partial (ammOxidation and Oxidative Dehydrogenation Catalysis on Mixed Metal Oxides

    Directory of Open Access Journals (Sweden)

    Jacques C. Védrine

    2016-01-01

    Full Text Available This paper presents an overview of heterogeneous partial (ammoxidation and oxidative dehydrogenation (ODH of hydrocarbons. The review has been voluntarily restricted to metal oxide-type catalysts, as the partial oxidation field is very broad and the number of catalysts is quite high. The main factors of solid catalysts for such reactions, designated by Grasselli as the “seven pillars”, and playing a determining role in catalytic properties, are considered to be, namely: isolation of active sites (known to be composed of ensembles of atoms, Me–O bond strength, crystalline structure, redox features, phase cooperation, multi-functionality and the nature of the surface oxygen species. Other important features and physical and chemical properties of solid catalysts, more or less related to the seven pillars, are also emphasized, including reaction sensitivity to metal oxide structure, epitaxial contact between an active phase and a second phase or its support, synergy effect between several phases, acid-base aspects, electron transfer ability, catalyst preparation and activation and reaction atmospheres, etc. Some examples are presented to illustrate the importance of these key factors. They include light alkanes (C1–C4 oxidation, ethane oxidation to ethylene and acetic acid on MoVTe(SbNb-O and Nb doped NiO, propene oxidation to acrolein on BiMoCoFe-O systems, propane (ammoxidation to (acrylonitrile acrylic acid on MoVTe(SbNb-O mixed oxides, butane oxidation to maleic anhydride on VPO: (VO2P2O7-based catalyst, and isobutyric acid ODH to methacrylic acid on Fe hydroxyl phosphates. It is shown that active sites are composed of ensembles of atoms whose size and chemical composition depend on the reactants to be transformed (their chemical and size features and the reaction mechanism, often of Mars and van Krevelen type. An important aspect is the fact that surface composition and surface crystalline structure vary with reaction on stream until

  5. Controllable film densification and interface flatness for high-performance amorphous indium oxide based thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Ou-Yang, Wei, E-mail: OUYANG.Wei@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Mitoma, Nobuhiko; Kizu, Takio; Gao, Xu; Lin, Meng-Fang; Tsukagoshi, Kazuhito, E-mail: OUYANG.Wei@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp [International Center for Materials Nanoarchitectronics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Nabatame, Toshihide [MANA Foundry and MANA Advanced Device Materials Group, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2014-10-20

    To avoid the problem of air sensitive and wet-etched Zn and/or Ga contained amorphous oxide transistors, we propose an alternative amorphous semiconductor of indium silicon tungsten oxide as the channel material for thin film transistors. In this study, we employ the material to reveal the relation between the active thin film and the transistor performance with aid of x-ray reflectivity study. By adjusting the pre-annealing temperature, we find that the film densification and interface flatness between the film and gate insulator are crucial for achieving controllable high-performance transistors. The material and findings in the study are believed helpful for realizing controllable high-performance stable transistors.

  6. Amorphous oxide alloys as interfacial layers with broadly tunable electronic structures for organic photovoltaic cells.

    Science.gov (United States)

    Zhou, Nanjia; Kim, Myung-Gil; Loser, Stephen; Smith, Jeremy; Yoshida, Hiroyuki; Guo, Xugang; Song, Charles; Jin, Hosub; Chen, Zhihua; Yoon, Seok Min; Freeman, Arthur J; Chang, Robert P H; Facchetti, Antonio; Marks, Tobin J

    2015-06-30

    In diverse classes of organic optoelectronic devices, controlling charge injection, extraction, and blocking across organic semiconductor-inorganic electrode interfaces is crucial for enhancing quantum efficiency and output voltage. To this end, the strategy of inserting engineered interfacial layers (IFLs) between electrical contacts and organic semiconductors has significantly advanced organic light-emitting diode and organic thin film transistor performance. For organic photovoltaic (OPV) devices, an electronically flexible IFL design strategy to incrementally tune energy level matching between the inorganic electrode system and the organic photoactive components without varying the surface chemistry would permit OPV cells to adapt to ever-changing generations of photoactive materials. Here we report the implementation of chemically/environmentally robust, low-temperature solution-processed amorphous transparent semiconducting oxide alloys, In-Ga-O and Ga-Zn-Sn-O, as IFLs for inverted OPVs. Continuous variation of the IFL compositions tunes the conduction band minima over a broad range, affording optimized OPV power conversion efficiencies for multiple classes of organic active layer materials and establishing clear correlations between IFL/photoactive layer energetics and device performance.

  7. Effects of oxygen stoichiometry on electrochromic properties in amorphous tungsten oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Inamdar, Akbar I.; Kim, Y.S.; Jang, B.U. [Department of Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of); Im, Hyunsik, E-mail: hyunsik7@dongguk.edu [Department of Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of); Jung, Woong [Department of Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of); Kim, Dae-Young [Department of Biological and Environmental Science, Dongguk University, Seoul 100-715 (Korea, Republic of); Kim, Hyungsang [Department of Physics, Dongguk University, Seoul 100-715 (Korea, Republic of)

    2012-06-01

    We have investigated the electrochromic properties of amorphous granular tungsten oxide (WO{sub 3+{delta}}) thin films with over-stoichiometric oxygen content ({delta}), using LiClO{sub 4} with propylene carbonate as an electrolyte. Different optical and electrochromic characteristics are observed with increasing {delta}. All the devices are electrochemically stable for more than 5000 color/bleach cycles without apparent degradation, and they have a faster response to coloration than to bleaching. WO{sub 3+{delta}} films with an optimized {delta} value show an optical modulation of 86% at a wavelength of 630 nm and the highest coloration efficiency ever reported of {approx} 213 cm{sup 2}/C. The {delta}-dependent coloration mechanism is discussed using the site saturation model. It is proposed that WO{sub 3+{delta}} films with the optimal {delta} value have favorable thickness and stoichiometry for the generation of Li{sup +}W{sup +5} states. - Highlights: Black-Right-Pointing-Pointer We report on electrochromic characteristics in WO{sub 3+{delta}} films. Black-Right-Pointing-Pointer Electrochromic properties of WO{sub 3+{delta}} films depend on different oxygen contents. Black-Right-Pointing-Pointer Coloration efficiency of 213 cm{sup 2}/C is obtained in a WO{sub 3+{delta}} film with an optimized {delta}. Black-Right-Pointing-Pointer The electrochromic mechanism is presented.

  8. Amorphous indium-gallium-zinc-oxide as electron transport layer in organic photodetectors

    Energy Technology Data Exchange (ETDEWEB)

    Arora, H. [IMEC, Kapeldreef 75, 3001 Leuven (Belgium); Phelma–Grenoble INP, 3 Parvis Louis Néel, 38016 Grenoble Cedex 01 (France); Malinowski, P. E., E-mail: pawel.malinowski@imec.be; Chasin, A.; Cheyns, D.; Steudel, S.; Schols, S. [IMEC, Kapeldreef 75, 3001 Leuven (Belgium); Heremans, P. [IMEC, Kapeldreef 75, 3001 Leuven (Belgium); ESAT, Katholieke Universiteit Leuven, Kasteelpark Arenberg 10, B-3001 Leuven (Belgium)

    2015-04-06

    Amorphous indium-gallium-zinc-oxide (a-IGZO) is demonstrated as an electron transport layer (ETL) in a high-performance organic photodetector (OPD). Dark current in the range of 10 nA/cm{sup 2} at a bias voltage of −2 V and a high photoresponse in the visible spectrum were obtained in inverted OPDs with poly(3-hexylthiophene) and phenyl-C{sub 61}-butyric acid methyl ester active layer. The best results were obtained for the optimum a-IGZO thickness of 7.5 nm with specific detectivity of 3 × 10{sup 12} Jones at the wavelength of 550 nm. The performance of the best OPD devices using a-IGZO was shown to be comparable to state-of-the-art devices based on TiO{sub x} as ETL, with higher rectification achieved in reverse bias. Yield and reproducibility were also enhanced with a-IGZO, facilitating fabrication of large area OPDs. Furthermore, easier integration with IGZO-based readout backplanes can be envisioned, where the channel material can be used as photodiode buffer layer after additional treatment.

  9. Mesoporous amorphous tungsten oxide electrochromic films: a Raman analysis of their good switching behavior

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Mesoporous films exhibit better electrochemical kinetics compared to the dense films. • Mesoporous films exhibit better reversibility compared to the dense films. • Li+cations disrupt WO3 network in a reversible way in the mesoporous film. • Li+ irreversibly intercalate in the voids of crystallites in the dense film. - Abstract: The intercalation and de-intercalation of lithium cations in electrochromic tungsten oxide thin films are significantly influenced by their structural and surface characteristics. In this study, we prepared two types of amorphous films via the sol-gel technique: one dense and one mesoporous in order to compare their response upon lithium intercalation and de-intercalation. According to chronoamperometric measurements, Li+ intercalates/de-intercalates faster in the mesoporous film (24s/6s) than in the dense film (48s/10s). The electrochemical measurements (cyclic voltammetry and chronoamperometry) also showed worse reversibility for the dense film compared to the mesoporous film, giving rise to important Li+ trapping and remaining coloration of the film. Raman analysis showed that the mesoporous film provides more accessible and various W-O surface bonds for Li+ intercalation. On the contrary, in the first electrochemical insertion and de-insertion in the dense film, Li+ selectively reacts with a few surface W-O bonds and preferentially intercalates into pre-existing crystallites to form stable irreversible LixWO3 bronze

  10. Water-soluble thin film transistors and circuits based on amorphous indium-gallium-zinc oxide.

    Science.gov (United States)

    Jin, Sung Hun; Kang, Seung-Kyun; Cho, In-Tak; Han, Sang Youn; Chung, Ha Uk; Lee, Dong Joon; Shin, Jongmin; Baek, Geun Woo; Kim, Tae-il; Lee, Jong-Ho; Rogers, John A

    2015-04-22

    This paper presents device designs, circuit demonstrations, and dissolution kinetics for amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) comprised completely of water-soluble materials, including SiNx, SiOx, molybdenum, and poly(vinyl alcohol) (PVA). Collections of these types of physically transient a-IGZO TFTs and 5-stage ring oscillators (ROs), constructed with them, show field effect mobilities (∼10 cm2/Vs), on/off ratios (∼2×10(6)), subthreshold slopes (∼220 mV/dec), Ohmic contact properties, and oscillation frequency of 5.67 kHz at supply voltages of 19 V, all comparable to otherwise similar devices constructed in conventional ways with standard, nontransient materials. Studies of dissolution kinetics for a-IGZO films in deionized water, bovine serum, and phosphate buffer saline solution provide data of relevance for the potential use of these materials and this technology in temporary biomedical implants. PMID:25805699

  11. Investigation of Phase Mixing in Amorphous Solid Dispersions of AMG 517 in HPMC-AS Using DSC, Solid-State NMR, and Solution Calorimetry.

    Science.gov (United States)

    Calahan, Julie L; Azali, Stephanie C; Munson, Eric J; Nagapudi, Karthik

    2015-11-01

    Intimate phase mixing between the drug and the polymer is considered a prerequisite to achieve good physical stability for amorphous solid dispersions. In this article, spray dried amorphous dispersions (ASDs) of AMG 517 and HPMC-as were studied by differential scanning calorimetry (DSC), solid-state NMR (SSNMR), and solution calorimetry. DSC analysis showed a weakly asymmetric (ΔTg ≈ 13.5) system with a single glass transition for blends of different compositions indicating phase mixing. The Tg-composition data was modeled using the BKCV equation to accommodate the observed negative deviation from ideality. Proton spin-lattice relaxation times in the laboratory and rotating frames ((1)H T1 and T1ρ), as measured by SSNMR, were consistent with the observation that the components of the dispersion were in intimate contact over a 10-20 nm length scale. Based on the heat of mixing calculated from solution calorimetry and the entropy of mixing calculated from the Flory-Huggins theory, the free energy of mixing was calculated. The free energy of mixing was found to be positive for all ASDs, indicating that the drug and polymer are thermodynamically predisposed to phase separation at 25 °C. This suggests that miscibility measured by DSC and SSNMR is achieved kinetically as the result of intimate mixing between drug and polymer during the spray drying process. This kinetic phase mixing is responsible for the physical stability of the ASD.

  12. Amorphous silica nanoparticles trigger nitric oxide/peroxynitrite imbalance in human endothelial cells: inflammatory and cytotoxic effects

    Directory of Open Access Journals (Sweden)

    Corbalan JJ

    2011-11-01

    Full Text Available J Jose Corbalan1,2, Carlos Medina1, Adam Jacoby2, Tadeusz Malinski2, Marek W Radomski11School of Pharmacy and Pharmaceutical Sciences, Faculty of Health Sciences, Panoz Institute, Trinity College Dublin, Dublin, Ireland; 2Department of Chemistry and Biochemistry, Ohio University, Athens, OH, USABackground: The purpose of this study was to investigate the mechanism of noxious effects of amorphous silica nanoparticles on human endothelial cells.Methods: Nanoparticle uptake was examined by transmission electron microscopy. Electrochemical nanosensors were used to measure the nitric oxide (NO and peroxynitrite (ONOO- released by a single cell upon nanoparticle stimulation. The downstream inflammatory effects were measured by an enzyme-linked immunosorbent assay, real-time quantitative polymerase chain reaction, and flow cytometry, and cytotoxicity was measured by lactate dehydrogenase assay.Results: We found that the silica nanoparticles penetrated the plasma membrane and rapidly stimulated release of cytoprotective NO and, to a greater extent, production of cytotoxic ONOO-. The low [NO]/[ONOO-] ratio indicated increased nitroxidative/oxidative stress and correlated closely with endothelial inflammation and necrosis. This imbalance was associated with nuclear factor κB activation, upregulation of key inflammatory factors, and cell death. These effects were observed in a nanoparticle size-dependent and concentration-dependent manner.Conclusion: The [NO]/[ONOO-] imbalance induced by amorphous silica nanoparticles indicates a potentially deleterious effect of silica nanoparticles on vascular endothelium.Keywords: amorphous silica nanoparticles, nanotoxicology, nitric oxide, peroxynitrite, inflammation, risk factors

  13. Oxygen effect of transparent conducting amorphous Indium Zinc Tin Oxide films on Polyimide substrate for flexible electrode

    International Nuclear Information System (INIS)

    This paper discusses the effect of oxygen on the transparent conducting properties and mechanical durability of the amorphous indium zinc tin oxide (IZTO) films. IZTO films deposited on flexible clear polyimide (PI) substrate using pulsed direct current (DC) magnetron sputtering at room temperature under various oxygen partial pressures. All IZTO films deposited at room temperature exhibit an amorphous structure. The electrical and optical properties of the IZTO films were sensitively influenced by oxygen partial pressures. At optimized deposition condition of 3.0% oxygen partial pressure, the IZTO film shows the lowest resistivity of 6.4 × 10−4 Ωcm, high transmittance of over 80% in the visible range, and figure of merit value of 3.6 × 10−3 Ω−1 without any heat controls. In addition, high work function and good mechanical flexibility of amorphous IZTO films are beneficial to flexible applications. It is proven that the proper oxygen partial pressure is important parameter to enhance the transparent conducting properties of IZTO films on PI substrate deposited at room temperature. - Highlights: • Indium zinc tin oxide (IZTO) films were deposited on polyimide at room temperature. • Transparent conducting properties of IZTO were influenced with oxygen partial pressure. • The smooth surface and high work function of IZTO were beneficial to anode layer. • The mechanical reliability of IZTO shows better performance to indium tin oxide film

  14. Design and synthesis of mixed oxides nanoparticles for biofuel applications

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Senniang [Iowa State Univ., Ames, IA (United States)

    2010-05-15

    The work in this dissertation presents the synthesis of two mixed metal oxides for biofuel applications and NMR characterization of silica materials. In the chapter 2, high catalytic efficiency of calcium silicate is synthesized for transesterfication of soybean oil to biodisels. Chapter 3 describes the synthesis of a new Rh based catalyst on mesoporous manganese oxides. The new catalyst is found to have higher activity and selectivity towards ethanol. Chapter 4 demonstrates the applications of solid-state Si NMR in the silica materials.

  15. Determination of photocatalytic activity in amorphous and crystalline titanium oxide films prepared using plasma-enhanced chemical vapor deposition

    Science.gov (United States)

    Wu, Cheng-Yang; Chiang, Bo-Sheng; Chang, Springfield; Liu, Day-Shan

    2011-01-01

    Hydro-oxygenated amorphous titanium oxide (a-TiO x:OH) films were prepared by plasma-enhanced chemical vapor deposition (PECVD) using precursors of titanium tetraisopropoxide (TTIP) and oxygen. The influences of chemical states and crystal quality on the photocatalytic activity were systematically investigated in the as-deposited and post-annealed films. The degree of the photocatalytic activity was deeply correlated with the porosity related to the hydroxyl (OH) groups in the as-deposited amorphous film. The crystallized anatase structures was observed from the 200 °C-deposited a-TiO x:OH film after a post-annealing treatment at 400 °C. The photocatalytic activity related to the film with anatase structure was markedly superior to that of an amorphous film with porous structures. The larger the crystal size of the anatase structure, the higher the photocatalytic activity obtained. At elevated annealed temperatures, the inferior anatase structure due to the crystalline transformation led to a low photocatalytic activity. It was concluded that the photocatalytic activity of an amorphous TiO x film prepared using PECVD was determined by the porosity originating from the functional OH groups in the film, whereas the crystalline quality of anatase phase in the annealed poly-TiO x film was crucial to the photocatalytic activity.

  16. Ballistic impact properties of mixed multi-layered amorphous surface alloyed materials fabricated by high-energy electron-beam irradiation

    International Nuclear Information System (INIS)

    The objective of this study is to investigate ballistic impact properties of multi-layered amorphous surface alloyed materials fabricated by high-energy electron-beam irradiation. The mixture of Zr-based amorphous alloy powders and LiF+MgF2 flux powders was deposited on a Ti alloy substrate, and then electron beam was irradiated on this powder mixture to fabricate an one-layered surface alloyed material. On top of this layer, the powder mixture was deposited again and then irradiated with electron beam whose beam current was decreased to fabricate the multi-layered surface alloyed material. In the mixed multi-layered surface alloyed materials fabricated with LM1 alloy powders and LM2 or LM10 alloy powders, the surface region consisted of amorphous phases, together with a small amount of crystalline particles, whereas the center region was complicatedly composed of amorphous phases, crystallized phases, and dendritic β phases. Since the surface region mostly composed of amorphous matrix was quite hard, the alloyed materials sufficiently blocked the travel of a projectile. When cracks formed at the surface region propagated into the center region, the formation of many cracks or debris was accelerated, which could beneficially work for absorbing the ballistic impact energy, thereby leading to the higher ballistic impact properties than the surface alloyed materials fabricated with LM1 or LM2 alloy powders

  17. Development of advanced mixed oxide fuels for plutonium management

    International Nuclear Information System (INIS)

    A number of advanced Mixed Oxide (MOX) fuel forms are currently being investigated at Los Alamos National Laboratory that have the potential to be effective plutonium management tools. Evolutionary Mixed Oxide (EMOX) fuel is a slight perturbation on standard MOX fuel, but achieves greater plutonium destruction rates by employing a fractional nonfertile component. A pure nonfertile fuel is also being studied. Initial calculations show that the fuel can be utilized in existing light water reactors and tailored to address different plutonium management goals (i.e., stabilization or reduction of plutonium inventories residing in spent nuclear fuel). In parallel, experiments are being performed to determine the feasibility of fabrication of such fuels. Initial EMOX pellets have successfully been fabricated using weapons-grade plutonium

  18. Microstructure and thermophysical characterization of mixed oxide fuels

    Energy Technology Data Exchange (ETDEWEB)

    Freibert, Franz J [Los Alamos National Laboratory; Salich, Tarik A [Los Alamos National Laboratory; Schwartz, Daniel S [Los Alamos National Laboratory; Hampel, Fred G [Los Alamos National Laboratory; Mitchell, Jeremy N [Los Alamos National Laboratory; Davis, Charles C [Los Alamos National Laboratory; Neuman, Angelique D [Los Alamos National Laboratory; Willson, Steve P [Los Alamos National Laboratory; Dunwoody, John T [Los Alamos National Laboratory

    2009-01-01

    Pre-irradiated thermodynamic and microstructural properties of nuclear fuels form the necessary set of data against which to gauge fuel performance and irradiation damage evolution. This paper summarizes recent efforts in mixed-oxide and minor actinide-bearing mixed-oxide ceramic fuels fabrication and characterization at Los Alamos National Laboratory. Ceramic fuels (U{sub 1-x-y-z}u{sub x}Am{sub y}Np{sub z})O{sub 2} fabricated in the compositional ranges of 0.19 {le} x {le} 0.3 Pu, 0 {le} y {le} 0.05 Am, and O {le} z {le} O.03 Np exhibited a uniform crystalline face-centered cubic phase with an average grain size of 14{micro}m; however, electron microprobe analysis revealed segregation of NpO{sub 2} in minor actinide-bearing fuels. Immersion density and porosity analysis demonstrated an average density of 92.4% theoretical for mixed-oxide fuels and an average density of 89.5 % theoretical density for minor actinide-bearing mixed-oxide fuels. Examined fuels exhibited mean thermal expansion value of 12.56 x 10{sup -6} C{sup -1} for temperature range (100 C < T < 1500 C) and ambient temperature Young's modulus and Poisson's ratio of 169 GPa and of 0.327, respectively. Internal dissipation as determined from mechanical resonances of these ceramic fuels has shown promise as a tool to gauge microstructural integrity and to interrogate fundamental properties.

  19. Selective oxidation of benzylic alcohols using copper-manganese mixed oxide nanoparticles as catalyst

    Directory of Open Access Journals (Sweden)

    Roushown Ali

    2015-07-01

    Full Text Available The catalytic activity of copper-manganese (CuMn2 mixed oxide nanoparticles (Cu/Mn = 1:2 has been studied for the selective oxidation of benzylic alcohols to the corresponding aldehydes using molecular oxygen as an oxidizing agent. The CuMn2 mixed oxide showed excellent catalytic activity for the oxidation of benzylic alcohols to the corresponding aldehydes with high selectivity (>99%. The complete conversion (100% of all the benzylic alcohols to the corresponding aldehydes is achieved within a short reaction period at 102 °C. The catalytic performance is obtained to be dependent on the electronic and steric effects of the substituents present on the phenyl ring. Electron withdrawing and bulky groups attached to the phenyl ring required longer reaction time for a complete conversion of the benzylic alcohols.

  20. Electrothermal Annealing (ETA) Method to Enhance the Electrical Performance of Amorphous-Oxide-Semiconductor (AOS) Thin-Film Transistors (TFTs).

    Science.gov (United States)

    Kim, Choong-Ki; Kim, Eungtaek; Lee, Myung Keun; Park, Jun-Young; Seol, Myeong-Lok; Bae, Hagyoul; Bang, Tewook; Jeon, Seung-Bae; Jun, Sungwoo; Park, Sang-Hee K; Choi, Kyung Cheol; Choi, Yang-Kyu

    2016-09-14

    An electro-thermal annealing (ETA) method, which uses an electrical pulse of less than 100 ns, was developed to improve the electrical performance of array-level amorphous-oxide-semiconductor (AOS) thin-film transistors (TFTs). The practicality of the ETA method was experimentally demonstrated with transparent amorphous In-Ga-Zn-O (a-IGZO) TFTs. The overall electrical performance metrics were boosted by the proposed method: up to 205% for the trans-conductance (gm), 158% for the linear current (Ilinear), and 206% for the subthreshold swing (SS). The performance enhancement were interpreted by X-ray photoelectron microscopy (XPS), showing a reduction of oxygen vacancies in a-IGZO after the ETA. Furthermore, by virtue of the extremely short operation time (80 ns) of ETA, which neither provokes a delay of the mandatory TFTs operation such as addressing operation for the display refresh nor demands extra physical treatment, the semipermanent use of displays can be realized. PMID:27552134

  1. Structural and thermal investigation of gadolinium gallium mixed oxides obtained by coprecipitation: Observation of a new metastable phase

    Science.gov (United States)

    Bazzoni, Marco; Bettinelli, Marco; Daldosso, Matteo; Enzo, Stefano; Serra, Filomena; Speghini, Adolfo

    2005-07-01

    Polycrystalline gadolinium gallium mixed oxides were prepared by coprecipitation and annealing at various temperatures below 1000 °C. The oxide materials appear to be X-ray amorphous after a heat treatment at 500 °C for 30 h, but after 30 h at 800 and 900 °C a major, unreported, hexagonal phase, isostructural with TAlO 3 compounds (where T=Y, Eu, Gd, Tb, Dy, Ho, Er) appears to crystallize. On the other hand, a highly energetic mechanical treatment of the amorphous powder previously annealed at 500 °C changes considerably the shape and position of exothermal events occurring in the range from 700 up to 900 °C. Subsequent annealing at 900 °C of the mechanically treated powder gives rise to the complete formation of the Gd 3Ga 5O 12 garnet structure at the expense of the hexagonal phase and of the minor Gd 4Ga 2O 9 oxide phase. However, a 7.0 wt% contamination is found to be due to tetragonal zirconia coming from vials and balls colliding media. The garnet phase may have strong deviations from the nominal stoichiometry of the garnet, as suggested by the refined lattice parameter obtained from the powder diffraction patterns and by the remarkable absence of intensity relative to the (220) Bragg peak position.

  2. Structural and thermal investigation of gadolinium gallium mixed oxides obtained by coprecipitation: Observation of a new metastable phase

    International Nuclear Information System (INIS)

    Polycrystalline gadolinium gallium mixed oxides were prepared by coprecipitation and annealing at various temperatures below 1000 deg. C. The oxide materials appear to be X-ray amorphous after a heat treatment at 500 deg. C for 30 h, but after 30 h at 800 and 900 deg. C a major, unreported, hexagonal phase, isostructural with TAlO3 compounds (where T=Y, Eu, Gd, Tb, Dy, Ho, Er) appears to crystallize. On the other hand, a highly energetic mechanical treatment of the amorphous powder previously annealed at 500 deg. C changes considerably the shape and position of exothermal events occurring in the range from 700 up to 900 deg. C. Subsequent annealing at 900 deg. C of the mechanically treated powder gives rise to the complete formation of the Gd3Ga5O12 garnet structure at the expense of the hexagonal phase and of the minor Gd4Ga2O9 oxide phase. However, a 7.0 wt% contamination is found to be due to tetragonal zirconia coming from vials and balls colliding media. The garnet phase may have strong deviations from the nominal stoichiometry of the garnet, as suggested by the refined lattice parameter obtained from the powder diffraction patterns and by the remarkable absence of intensity relative to the (220) Bragg peak position

  3. Amorphous film thickness dependence for epitaxy of perovskite oxide films under excimer laser irradiation

    International Nuclear Information System (INIS)

    We have studied the epitaxial growth of perovskite manganite LaMnO3 (LMO) on SrTiO3(1 0 0) in the excimer laser assisted metal organic deposition process. The LMO was preferentially grown from the substrate surface by the KrF laser irradiation. The study of amorphous LMO film thickness dependence on epitaxial growth under the excimer laser irradiation revealed that the photo-thermal heating effect strongly depended on the amorphous film thickness due to a low thermal conductivity of amorphous LMO: the ion-migration for chemical bond-forming at the reaction interface would be strongly enhanced in the amorphous LMO film with the large film thickness about 210 nm. On the other hand, the photo-chemical effect occurred efficiently for the amorphous film thickness in the range of 35-210 nm. These results indicate that the epitaxial growing rate was dominated by the photo-thermal heating after the photo-chemical activation at the growth interface.

  4. Codoping of zinc and tungsten for practical high-performance amorphous indium-based oxide thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Kizu, Takio, E-mail: KIZU.Takio@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Mitoma, Nobuhiko; Tsukagoshi, Kazuhito, E-mail: KIZU.Takio@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Miyanaga, Miki; Awata, Hideaki [Advanced Materials R& D Laboratories, Sumitomo Electric Industries, Ltd., 1-1-1 Koyakita, Itami, Hyogo 664-0016 (Japan); Nabatame, Toshihide [MANA Foundry and MANA Advanced Device Materials Group, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2015-09-28

    Using practical high-density sputtering targets, we investigated the effect of Zn and W codoping on the thermal stability of the amorphous film and the electrical characteristics in thin film transistors. zinc oxide is a potentially conductive component while W oxide is an oxygen vacancy suppressor in oxide films. The oxygen vacancy from In-O and Zn-O was suppressed by the W additive because of the high oxygen bond dissociation energy. With controlled codoping of W and Zn, we demonstrated a high mobility with a maximum mobility of 40 cm{sup 2}/V s with good stability under a negative bias stress in InWZnO thin film transistors.

  5. Codoping of zinc and tungsten for practical high-performance amorphous indium-based oxide thin film transistors

    International Nuclear Information System (INIS)

    Using practical high-density sputtering targets, we investigated the effect of Zn and W codoping on the thermal stability of the amorphous film and the electrical characteristics in thin film transistors. zinc oxide is a potentially conductive component while W oxide is an oxygen vacancy suppressor in oxide films. The oxygen vacancy from In-O and Zn-O was suppressed by the W additive because of the high oxygen bond dissociation energy. With controlled codoping of W and Zn, we demonstrated a high mobility with a maximum mobility of 40 cm2/V s with good stability under a negative bias stress in InWZnO thin film transistors

  6. Advantages of using amorphous indium zinc oxide films for window layer in Cu(In,Ga)Se2 solar cells

    International Nuclear Information System (INIS)

    The advantages of using indium zinc oxide (IZO) films instead of conventional Ga-doped zinc oxide (ZnO:Ga) films for Cu(In,Ga)Se2 (CIGS) solar cells are described. The electrical properties of IZO are independent of film thickness. IZO films have higher mobility (30–40 cm2/Vs) and lower resistivity (4–5 × 10−4 Ω cm) compared to ZnO:Ga films deposited without intentional heating, because the number of grain boundaries in amorphous IZO films is small. The properties of a CIGS solar cell using IZO at the window layer were better than those obtained using a conventional ZnO:Ga at the window layer; moreover, the properties tended to be independent of thickness. These results indicate that use of IZO as a transparent conducting oxide layer is expected to increase the efficiency of CIGS solar cells.

  7. Mechanism of Selenite Removal by a Mixed Adsorbent Based on Fe–Mn Hydrous Oxides Studied Using X-ray Absorption Spectroscopy

    KAUST Repository

    Chubar, Natalia

    2014-11-18

    © 2014 American Chemical Society. Selenium cycling in the environment is greatly controlled by various minerals, including Mn and Fe hydrous oxides. At the same time, such hydrous oxides are the main inorganic ion exchangers suitable (on the basis of their chemical nature) to sorb (toxic) anions, separating them from water solutions. The mechanism of selenite adsorption by the new mixed adsorbent composed of a few (amorphous and crystalline) phases [maghemite, MnCO3, and X-ray amorphous Fe(III) and Mn(III) hydrous oxides] was studied by extended X-ray absorption fine structure (EXAFS) spectroscopy [supported by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) data]. The complexity of the porous adsorbent, especially the presence of the amorphous phases of Fe(III) and Mn(III) hydrous oxides, is the main reason for its high selenite removal performance demonstrated by batch and column adsorption studies shown in the previous work. Selenite was bound to the material via inner-sphere complexation (via oxygen) to the adsorption sites of the amorphous Fe(III) and Mn(III) oxides. This anion was attracted via bidentate binuclear corner-sharing coordination between SeO3 2- trigonal pyramids and both FeO6 and MnO6 octahedra; however, the adsorption sites of Fe(III) hydrous oxides played a leading role in selenite removal. The contribution of the adsorption sites of Mn(III) oxide increased as the pH decreased from 8 to 6. Because most minerals have a complex structure (they are seldom based on individual substances) of various crystallinity, this work is equally relevant to environmental science and environmental technology because it shows how various solid phases control cycling of chemical elements in the environment.

  8. Effects of amorphous silica coating on cerium oxide nanoparticles induced pulmonary responses

    Science.gov (United States)

    Ma, Jane; Mercer, Robert R.; Barger, Mark; Schwegler-Berry, Diane; Cohen, Joel M.; Demokritou, Philip; Castranova, Vincent

    2015-01-01

    Recently cerium compounds have been used in a variety of consumer products, including diesel fuel additives, to increase fuel combustion efficiency and decrease diesel soot emissions. However, cerium oxide (CeO2) nanoparticles have been detected in the exhaust, which raises a health concern. Previous studies have shown that exposure of rats to nanoscale CeO2 by intratracheal instillation (IT) induces sustained pulmonary inflammation and fibrosis. In the present study, male Sprague–Dawley rats were exposed to CeO2 or CeO2 coated with a nano layer of amorphous SiO2 (aSiO2/CeO2) by a single IT and sacrificed at various times post-exposure to assess potential protective effects of the aSiO2 coating. The first acellular bronchoalveolar lavage (BAL) fluid and BAL cells were collected and analyzed from all exposed animals. At the low dose (0.15 mg/kg), CeO2 but not aSiO2/CeO2 exposure induced inflammation. However, at the higher doses, both particles induced a dose-related inflammation, cytotoxicity, inflammatory cytokines, matrix metalloproteinase (MMP)-9, and tissue inhibitor of MMP at 1 day post-exposure. Morphological analysis of lung showed an increased inflammation, surfactant and collagen fibers after CeO2 (high dose at 3.5 mg/kg) treatment at 28 days post-exposure. aSiO2 coating significantly reduced CeO2-induced inflammatory responses in the airspace and appeared to attenuate phospholipidosis and fibrosis. Energy dispersive X-ray spectroscopy analysis showed Ce and phosphorous (P) in all particle-exposed lungs, whereas Si was only detected in aSiO2/CeO2-exposed lungs up to 3 days after exposure, suggesting that aSiO2 dissolved off the CeO2 core, and some of the CeO2 was transformed to CePO4 with time. These results demonstrate that aSiO2 coating reduce CeO2-induced inflammation, phospholipidosis and fibrosis. PMID:26210349

  9. Analysis of the porosity distribution of mixed oxide pins

    International Nuclear Information System (INIS)

    In the frame of the Joint Irradiation Program IVO-FR2-Vg7 between the Centre of Nuclear Research of Karlsruhe (KfK), the irradiation of 30 mixed-oxide fuel rods in the FR2 experimental reactor was carried out. The pins were located in 10 single-walled NaK capsules. The behaviour of the fuel during its burnup was studied, mainly, the rest-porosity and cracking distribution in the pellet, partial densification, etc. In this work 3 pins from the capsule No. 165 were analyzed. The experimental results (pore and cracking profiles) were interpreted by the fuel rod code SATURN. (Author) 20 refs

  10. Preparation of Well Dispersed and Ultra-Fine Ce(Zr)O2 Mixed Oxide by Mechanochemical Processing

    Institute of Scientific and Technical Information of China (English)

    程昌明; 李永绣; 周雪珍; 陈伟凡

    2004-01-01

    Ultra-fine CeO2-ZrO2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce2(CO3)3·8H2O, ZrOCl2·xH2O and ammonia were used as reactants. It is found that the crystalline Ce2(CO3)3·8H2O and ZrOCl2·xH2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce0.15Zr0.85O2 mixed oxide with pure tetragonal phase structure and medium particle size(D50)less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.

  11. Amorphous GeOx-Coated Reduced Graphene Oxide Balls with Sandwich Structure for Long-Life Lithium-Ion Batteries.

    Science.gov (United States)

    Choi, Seung Ho; Jung, Kyeong Youl; Kang, Yun Chan

    2015-07-01

    Amorphous GeOx-coated reduced graphene oxide (rGO) balls with sandwich structure are prepared via a spray-pyrolysis process using polystyrene (PS) nanobeads as sacrificial templates. This sandwich structure is formed by uniformly coating the exterior and interior of few-layer rGO with amorphous GeOx layers. X-ray photoelectron spectroscopy analysis reveals a Ge:O stoichiometry ratio of 1:1.7. The amorphous GeOx-coated rGO balls with sandwich structure have low charge-transfer resistance and fast Li(+)-ion diffusion rate. For example, at a current density of 2 A g(-1), the GeOx-coated rGO balls with sandwich and filled structures and the commercial GeO2 powders exhibit initial charge capacities of 795, 651, and 634 mA h g(-1), respectively; the corresponding 700th-cycle charge capacities are 758, 579, and 361 mA h g(-1). In addition, at a current density of 5 A g(-1), the rGO balls with sandwich structure have a 1600th-cycle reversible charge capacity of 629 mA h g(-1) and a corresponding capacity retention of 90.7%, as measured from the maximum reversible capacity at the 100th cycle.

  12. Amorphous GeOx-Coated Reduced Graphene Oxide Balls with Sandwich Structure for Long-Life Lithium-Ion Batteries.

    Science.gov (United States)

    Choi, Seung Ho; Jung, Kyeong Youl; Kang, Yun Chan

    2015-07-01

    Amorphous GeOx-coated reduced graphene oxide (rGO) balls with sandwich structure are prepared via a spray-pyrolysis process using polystyrene (PS) nanobeads as sacrificial templates. This sandwich structure is formed by uniformly coating the exterior and interior of few-layer rGO with amorphous GeOx layers. X-ray photoelectron spectroscopy analysis reveals a Ge:O stoichiometry ratio of 1:1.7. The amorphous GeOx-coated rGO balls with sandwich structure have low charge-transfer resistance and fast Li(+)-ion diffusion rate. For example, at a current density of 2 A g(-1), the GeOx-coated rGO balls with sandwich and filled structures and the commercial GeO2 powders exhibit initial charge capacities of 795, 651, and 634 mA h g(-1), respectively; the corresponding 700th-cycle charge capacities are 758, 579, and 361 mA h g(-1). In addition, at a current density of 5 A g(-1), the rGO balls with sandwich structure have a 1600th-cycle reversible charge capacity of 629 mA h g(-1) and a corresponding capacity retention of 90.7%, as measured from the maximum reversible capacity at the 100th cycle. PMID:26047208

  13. Electromechanical properties of amorphous indium-gallium-zinc-oxide transistors structured with an island configuration on plastic

    Science.gov (United States)

    Park, Chang Bum; Na, Hyung Il; Yoo, Soon Sung; Park, Kwon-Shik

    2016-03-01

    A comparative study of the electromechanical properties was carried out on a low-temperature-processed amorphous indium-gallium-zinc-oxide thin-film transistor, particularly with regard to the structural design of the device under the stress accumulation of an outward bending surface. Shown herein is the reliable electromechanical integrity of island-structured devices against the mechanical strain at bending radii of mm order. The onset of crack strain also closely corresponded to the electrical failure of the stressed device. These results revealed that the island configuration on the bending surface effectively suppresses the stress accumulation on sheets composed of inorganic stacked layers in a uniaxial direction.

  14. Understanding the hydrogen and oxygen gas pressure dependence of the tribological properties of silicon oxide-doped hydrogenated amorphous carbon coatings

    OpenAIRE

    Koshigan, KD; Mangolini, F; McClimon, JB; Vacher, B.; Bec, S; Carpick, RW; Fontaine, J

    2015-01-01

    Silicon oxide-doped hydrogenated amorphous carbons (a–C:H:Si:O) are amorphous thin films used as solid lubricants in a range of commercial applications, thanks to its increased stability in extreme environments, relative to amorphous hydrogenated carbons (a–C:H). This work aims to develop a fundamental understanding of the environmental impact on the tribology of a–C:H:Si:O. Upon sliding an a–C:H:Si:O film against a steel counterbody, two friction regimes develop: high friction in high vacuum...

  15. Ferroelectric switching of poly(vinylidene difluoride-trifluoroethylene) in metal-ferroelectric-semiconductor non-volatile memories with an amorphous oxide semiconductor

    NARCIS (Netherlands)

    Gelinck, G.H.; Breemen, A.J.J.M. van; Cobb, B.

    2015-01-01

    Ferroelectric polarization switching of poly(vinylidene difluoride-trifluoroethylene) is investigated in different thin-film device structures, ranging from simple capacitors to dual-gate thin-film transistors (TFT). Indium gallium zinc oxide, a high mobility amorphous oxide material, is used as sem

  16. Ceria doped mixed metal oxide nanoparticles as oxidation catalysts: Synthesis and their characterization

    Directory of Open Access Journals (Sweden)

    S.S.P. Sultana

    2015-11-01

    Full Text Available Mixed metal nanoparticles (NPs have attracted significant attention as catalysts for various organic transformations. In this study, we have demonstrated the preparation of nickel–manganese mixed metal oxide NPs doped with X% nano cerium oxide (X = 1, 3, 5 mol% by a facile co-precipitation technique using surfactant and surfactant free methodologies. The as-synthesized materials were calcined at different temperatures (300 °C, 400 °C, and 500 °C, and were characterized using various spectroscopic techniques, including, FTIR and XRD. SEM analysis, TEM analysis and TGA were employed to evaluate the structural properties of the as-prepared catalyst. These were evaluated for their catalytic behaviour towards the conversion of benzyl alcohol to benzaldehyde, which was used as a model reaction with molecular oxygen as oxidant. Furthermore, the effect of the variation of the percentage of nano ceria doping and the calcination temperature on the performance of as-prepared mixed metal catalysts was also evaluated. The kinetic studies of the reactions performed employing gas chromatographic technique have revealed that the mixed metal oxide catalyst doped with 5% nano ceria displayed excellent catalytc activity, among various catalysts synthesized.

  17. Electrochemical Tuning of Amorphous Carbon Amount and Surface Oxidation Degree of Graphitic Quantum Dots.

    Science.gov (United States)

    Wang, Jun; Li, Yan; Zhang, Bo-Ping; Ma, Ning; Ge, Juan; Li, Ling; Li, Ting; Liu, Qian-Qian

    2016-04-01

    Graphitic quantum dots (GQDs) have attracted much interesting of researchers because of its amazing optical properties and its ability to be used for many applications. Now, there are various methods have been reported for preparation of GQDs. Among them electrochemical method is simple technology, while it can afford various conditions to realize controllable prepared of GQDs. In this study, we tuned the PH values of electrolyte to probe the relationship of electrolyte environment and GQDs' optical properties as well as to seek the effective controllable condition for GQDs' preparation. It is found that the density of oxygen-related functional groups and the amount of amorphous carbon of GQDs were related to the PH values of electrolyte. The amount of amorphous carbon decreased as the PH values increased in the region of 6.6 to 7.1. Although, the positions of photoluminescence (PL) peak almost no changed of GQDs with different density of oxygen-related functional groups, GQDs with the lowest amount of amorphous carbon achieved the maximum PL intensity. Therefore, controlling amorphous carbon's amount by electrochemical method may afford a new direction to improve the fluorescence (FL) emission of GQDs. PMID:27451661

  18. Ion sensing properties of vanadium/tungsten mixed oxides

    International Nuclear Information System (INIS)

    Vanadium/tungsten mixed oxide (V2O5/WO3) sensing membranes were deposited on glassy carbon substrates and used as the H+ sensor of the extended gate field effect transistor (EGFET) device. X-ray diffractograms indicated a decrease of the interplanar spacing of V2O5 after the insertion of WO3 revealing that the lamellar structure is under compressive stress. The crystallinity increases with increasing WO3 molar ratio. The film is not homogeneous, with more WO3 material sitting at the surface. This influences the response of pH sensors using the EGFET configuration. The maximum sensitivity of 68 mV pH-1 was obtained for the sample with 5% WO3 molar ratio. For higher WO3 molar ratios, the behavior is not linear. It can be concluded that V2O5 dominates for acidic solutions while WO3 dominates for basic solutions. Therefore, the mixed oxide with low amount of WO3 is the main candidate for further use as biosensor.

  19. Ion sensing properties of vanadium/tungsten mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Guidelli, Eder Jose, E-mail: ederguidelli@gmail.com [Departamento de Fisica e Matematica, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirao Preto, SP (Brazil); Guerra, Elidia Maria [Universidade Federal de Sao Joao Del Rei, CAP, Ouro Branco-MG (Brazil); Mulato, Marcelo [Departamento de Fisica e Matematica, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirao Preto, SP (Brazil)

    2011-02-15

    Vanadium/tungsten mixed oxide (V{sub 2}O{sub 5}/WO{sub 3}) sensing membranes were deposited on glassy carbon substrates and used as the H{sup +} sensor of the extended gate field effect transistor (EGFET) device. X-ray diffractograms indicated a decrease of the interplanar spacing of V{sub 2}O{sub 5} after the insertion of WO{sub 3} revealing that the lamellar structure is under compressive stress. The crystallinity increases with increasing WO{sub 3} molar ratio. The film is not homogeneous, with more WO{sub 3} material sitting at the surface. This influences the response of pH sensors using the EGFET configuration. The maximum sensitivity of 68 mV pH{sup -1} was obtained for the sample with 5% WO{sub 3} molar ratio. For higher WO{sub 3} molar ratios, the behavior is not linear. It can be concluded that V{sub 2}O{sub 5} dominates for acidic solutions while WO{sub 3} dominates for basic solutions. Therefore, the mixed oxide with low amount of WO{sub 3} is the main candidate for further use as biosensor.

  20. Preparation of uniform nanoparticles of ultra-high purity metal oxides, mixed metal oxides, metals, and metal alloys

    Science.gov (United States)

    Woodfield, Brian F.; Liu, Shengfeng; Boerio-Goates, Juliana; Liu, Qingyuan; Smith, Stacey Janel

    2012-07-03

    In preferred embodiments, metal nanoparticles, mixed-metal (alloy) nanoparticles, metal oxide nanoparticles and mixed-metal oxide nanoparticles are provided. According to embodiments, the nanoparticles may possess narrow size distributions and high purities. In certain preferred embodiments, methods of preparing metal nanoparticles, mixed-metal nanoparticles, metal oxide nanoparticles and mixed-metal nanoparticles are provided. These methods may provide tight control of particle size, size distribution, and oxidation state. Other preferred embodiments relate to a precursor material that may be used to form nanoparticles. In addition, products prepared from such nanoparticles are disclosed.

  1. Structure and Catalytic Behavior of CuO-ZrO-CeO2 Mixed Oxides

    Institute of Scientific and Technical Information of China (English)

    王恩过; 陈诵英

    2002-01-01

    The effect of doping CuO on the structure and properties of zirconia-ceria mixed oxide was studied. The results show that addition of CuO decreases the reduction temperature of ceria, and stabilizes the cubic structure of mixed oxides, and enhances catalytic activity of CuO-ZrO-CeO2 mixed oxides for CO oxidation. Increasing ceria content in the mixed oxides can enhance the catalytic activity, but some impurities such as sulfate make catalytic activity falling. There is little effect of calcination temperature on catalytic activities, implying that these catalysts are effective with good thermal stability.

  2. Amorphous silica nanoparticles trigger nitric oxide/peroxynitrite imbalance in human endothelial cells: inflammatory and cytotoxic effects

    Science.gov (United States)

    Corbalan, J Jose; Medina, Carlos; Jacoby, Adam; Malinski, Tadeusz; Radomski, Marek W

    2011-01-01

    Background The purpose of this study was to investigate the mechanism of noxious effects of amorphous silica nanoparticles on human endothelial cells. Methods Nanoparticle uptake was examined by transmission electron microscopy. Electrochemical nanosensors were used to measure the nitric oxide (NO) and peroxynitrite (ONOO−) released by a single cell upon nanoparticle stimulation. The downstream inflammatory effects were measured by an enzyme-linked immunosorbent assay, real-time quantitative polymerase chain reaction, and flow cytometry, and cytotoxicity was measured by lactate dehydrogenase assay. Results We found that the silica nanoparticles penetrated the plasma membrane and rapidly stimulated release of cytoprotective NO and, to a greater extent, production of cytotoxic ONOO−. The low [NO]/[ONOO−] ratio indicated increased nitroxidative/oxidative stress and correlated closely with endothelial inflammation and necrosis. This imbalance was associated with nuclear factor κB activation, upregulation of key inflammatory factors, and cell death. These effects were observed in a nanoparticle size-dependent and concentration-dependent manner. Conclusion The [NO]/[ONOO−] imbalance induced by amorphous silica nanoparticles indicates a potentially deleterious effect of silica nanoparticles on vascular endothelium. PMID:22131828

  3. Low-Temperature Photochemically Activated Amorphous Indium-Gallium-Zinc Oxide for Highly Stable Room-Temperature Gas Sensors.

    Science.gov (United States)

    Jaisutti, Rawat; Kim, Jaeyoung; Park, Sung Kyu; Kim, Yong-Hoon

    2016-08-10

    We report on highly stable amorphous indium-gallium-zinc oxide (IGZO) gas sensors for ultraviolet (UV)-activated room-temperature detection of volatile organic compounds (VOCs). The IGZO sensors fabricated by a low-temperature photochemical activation process and exhibiting two orders higher photocurrent compared to conventional zinc oxide sensors, allowed high gas sensitivity against various VOCs even at room temperature. From a systematic analysis, it was found that by increasing the UV intensity, the gas sensitivity, response time, and recovery behavior of an IGZO sensor were strongly enhanced. In particular, under an UV intensity of 30 mW cm(-2), the IGZO sensor exhibited gas sensitivity, response time and recovery time of 37%, 37 and 53 s, respectively, against 750 ppm concentration of acetone gas. Moreover, the IGZO gas sensor had an excellent long-term stability showing around 6% variation in gas sensitivity over 70 days. These results strongly support a conclusion that a low-temperature solution-processed amorphous IGZO film can serve as a good candidate for room-temperature VOCs sensors for emerging wearable electronics. PMID:27430635

  4. Mass transport in mixed conducting perovskite related oxides

    CERN Document Server

    Shaw, C K M

    2001-01-01

    mechanical and chemical stability of LSCN under practical operating temperatures have been measured and related to long term stability in typical SOFC assemblies. The phase stability and the effect of preparation conditions under different atmospheres on La sub 2 Ni sub 1 sub - sub x Co sub x O sub 4 sub + subdelta compounds were examined using high temperature X-ray diffraction. Fast oxygen uptake at low temperatures was observed in these studies indicating rapid oxygen diffusion, which was confirmed by isotope exchange investigations. The oxygen diffusion and surface exchange data obtained from IEDP-SIMS measurements of La sub 2 Ni sub 0 sub . sub 8 Co sub 0 sub . sub 2 O sub 4 sub + subdelta have enabled suppositions to be made regarding the reduction process and aided further interpretation of the defect model for these oxides. Mixed ionic electronic conducting oxides of the perovskite structure have attracted great interest in the field of solid oxide electrochemical devices. Their ability to allow poten...

  5. Microwave-Assisted Synthesis of Mixed Metal-Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Akrati Verma

    2013-01-01

    Full Text Available Nanoparticles of mixed metal oxides, ZrO2, ZrTiO4, and ZrV2O7 were prepared by microwave-assisted citrate sol-gel and solution combustion method. The prepared nanoparticles were characterized for their structural details using XRD and TEM techniques. The broadening of Raman bands is ascribed to local compositional fluctuations or local positional disordering produced due to random distribution of Zr4+ and Ti4+between equivalent sites. The XPS spectra confirm the incorporation of Ti in ZrO2 and suggest Zr as well as Ti in +4 oxidation state. Gelation and fast combustion seem to be the reason for smaller particle sizes. ZrV2O7 nanocrystalline material was synthesized by microwave- assisted solution combustion method. Low angle powder XRD measurements confirm the mesoporous nature of the prepared material. The effect of calcination temperature on the phase transformation of the materials has been investigated. Among tetragonal, monoclinic, and cubic phases, the monoclinic phase is predominant at higher calcinations temperature. The XPS confirms the incorporation of V2O5 in ZrO2 and suggests that Zr and V are in the same oxidation state (+4. The average particle sizes for ZrO2, ZrTiO4, and ZrV2O7 were found to be in the ranges of 5–10 nm, 2–5 nm, and 10–50 nm, respectively.

  6. Comparison of the electronic structure of amorphous versus crystalline indium gallium zinc oxide semiconductor: structure, tail states and strain effects

    Science.gov (United States)

    de Jamblinne de Meux, A.; Pourtois, G.; Genoe, J.; Heremans, P.

    2015-11-01

    We study the evolution of the structural and electronic properties of crystalline indium gallium zinc oxide (IGZO) upon amorphization by first-principles calculation. The bottom of the conduction band (BCB) is found to be constituted of a pseudo-band of molecular orbitals that resonate at the same energy on different atomic sites. They display a bonding character between the s orbitals of the metal sites and an anti-bonding character arising from the interaction between the oxygen and metal s orbitals. The energy level of the BCB shifts upon breaking of the crystal symmetry during the amorphization process, which may be attributed to the reduction of the coordination of the cationic centers. The top of the valence band (TVB) is constructed from anti-bonding oxygen p orbitals. In the amorphous state, they have random orientation, in contrast to the crystalline state. This results in the appearance of localized tail states in the forbidden gap above the TVB. Zinc is found to play a predominant role in the generation of these tail states, while gallium hinders their formation. Last, we study the dependence of the fundamental gap and effective mass of IGZO on mechanical strain. The variation of the gap under strain arises from the enhancement of the anti-bonding interaction in the BCB due to the modification of the length of the oxygen-metal bonds and/or to a variation of the cation coordination. This effect is less pronounced for the amorphous material compared to the crystalline material, making amorphous IGZO a semiconductor of choice for flexible electronics. Finally, the effective mass is found to increase upon strain, in contrast to regular materials. This counterintuitive variation is due to the reduction of the electrostatic shielding of the cationic centers by oxygen, leading to an increase of the overlaps between the metal orbitals at the origin of the delocalization of the BCB. For the range of strain typically met in flexible electronics, the induced

  7. Growth of ultrathin amorphous alumina films during the oxidation of NiAl(100)

    Science.gov (United States)

    Cai, Na; Qin, Hailang; Tong, Xiao; Zhou, Guangwen

    2013-12-01

    The effect of temperature on the oxidation of NiAl(100) is comparatively studied at 25 °C and 300 °C using X-ray Photoelectron Spectroscopy to elucidate the effect of oxide-alloy interfacial reaction on the growth of ultrathin alumina thin films. The oxidation at 25 °C results in self-limiting aluminum oxide film growth to a less extent of the limiting thickness regimes with non-stoichiometric oxide films exhibiting a deficiency of Al cations, whereas for the oxidation at 300 °C the oxide films grow to a larger limiting thickness with relatively enriched with Al at the limiting thickness. The temperature dependent limiting thickness and composition of the oxide films are ascribed to the transport velocity of Al from deeper layers to the oxide/alloy interface during the oxide growth. For the oxidation at 25 °C the oxide film growth depletes Al and forms an underlying Ni-rich interfacial layer that blocks the supply of Al atoms to the oxide/substrate interface, whereas for the oxidation at 300 °C the enhanced diffusion rate maintains adequate supply of Al atoms to the oxide/alloy interface to sustain the oxide film growth to the full extent of the limiting thickness.

  8. Perovskite-type Mixed Oxides Catalyst for Complete Oxidation of Acetone

    Institute of Scientific and Technical Information of China (English)

    DUAN; ZhiYing

    2001-01-01

    The catalytic oxidation of VOCs (volatile organic compounds) is an attractive subject in the field of environmental protection now. Furthermore, most countries have made out regulations m controlling the maximum content of VOCs in some places. Presently, the leading way of domestic and foreign means to eliminate VOCs is to completely oxidize VOCs into carbon dioxide and water in presence of noble metal catalyst. But noble metal is expensive for lack of resource[2]. So it is insistent to research a low-cost catalyst for removal of VOCs. In this work, we have used some base metals (such as La, Sr, Ce, Ni, Cu) to synthesize mixed oxides catalyst supported on γ-A12O3. We have investigated the catalytic properties in the complete oxidation of acetone over the catalyst prepared and achieved an exciting result.……

  9. Emission computer tomography on a Dodewaard mixed oxide fuel pin

    International Nuclear Information System (INIS)

    A nondestructive technique as well as a destructive PIE technique have been used to verify the results obtained with a newly 8-e computer tomography (GECT) system. Multi isotope Scanning (MIS), electron probe micro analysis (EPMA) and GECT were used on a mixed oxide (MOX) fuel rod from the Dodewaard reactor with an average burnup of 24 MWd/kg fuel. GECT shows migration of Cs to the periphery of fuel pellets and to radial cracks and pores in the fuel, whereas MIS shows Cs migration to pellet interfaces. The EPMA technique appeared not to be useful to show migration of Cs but, it shows the distribution of fission products from Pu. EPMA clearly shows the distribution of fission products from Pu, but did not reveal the Cs-migration. (orig./HP)

  10. Formation of nano-porous GeOx by de-alloying of an Al–Ge–Mn amorphous alloy

    International Nuclear Information System (INIS)

    The present study shows that nanometer-scale amorphous phase separation occurs by spinodal decomposition of the undercooled liquid in a melt-spun Al60Ge30Mn10 alloy, although there is no atomic pair with positive enthalpy of mixing. By adopting a proper de-alloying process, an interconnected nano-porous germanium oxide with an amorphous structure is successfully synthesized. The present study shows that nano-porous amorphous germanium oxide can be easily obtained by de-alloying of Al-based amorphous alloys with nm-scale composition fluctuation

  11. Yttrium bismuth titanate pyrochlore mixed oxides for photocatalytic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Merka, Oliver

    2012-10-18

    In this work, the sol-gel synthesis of new non-stoichiometric pyrochlore titanates and their application in photocatalytic hydrogen production is reported. Visible light response is achieved by introducing bismuth on the A site or by doping the B site by transition metal cations featuring partially filled d orbitals. This work clearly focusses on atomic scale structural changes induced by the systematical introduction of non-stoichiometry in pyrochlore mixed oxides and the resulting influence on the activity in photocatalytic hydrogen production. The materials were characterized in detail regarding their optical properties and their atomic structure. The pyrochlore structure tolerates tremendous stoichiometry variations. The non-stoichiometry in A{sub 2}O{sub 3} rich compositions is compensated by distortions in the cationic sub-lattice for the smaller Y{sup 3+} cation and by evolution of a secondary phase for the larger Bi{sup 3+} cation on the A site. For TiO{sub 2} rich compositions, the non-stoichiometry leads to a special vacancy formation in the A and optionally O' sites. It is shown that pyrochlore mixed oxides in the yttrium bismuth titanate system represent very active and promising materials for photocatalytic hydrogen production, if precisely and carefully tuned. Whereas Y{sub 2}Ti{sub 2}O{sub 7} yields stable hydrogen production rates over time, the bismuth richer compounds of YBiTi{sub 2}O{sub 7} and Bi{sub 2}Ti{sub 2}O{sub 7} are found to be not stable under irradiation. This drawback is overcome by applying a special co-catalyst system consisting of a precious metal core and a Cr{sub 2}O{sub 3} shell on the photocatalysts.

  12. Calculational Benchmark Problems for VVER-1000 Mixed Oxide Fuel Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Emmett, M.B.

    2000-03-17

    Standard problems were created to test the ability of American and Russian computational methods and data regarding the analysis of the storage and handling of Russian pressurized water reactor (VVER) mixed oxide fuel. Criticality safety and radiation shielding problems were analyzed. Analysis of American and Russian multiplication factors for fresh fuel storage for low-enriched uranium (UOX), weapons- (MOX-W) and reactor-grade (MOX-R) MOX differ by less than 2% for all variations of water density. For shielding calculations for fresh fuel, the ORNL results for the neutron source differ from the Russian results by less than 1% for UOX and MOX-R and by approximately 3% for MOX-W. For shielding calculations for fresh fuel assemblies, neutron dose rates at the surface of the assemblies differ from the Russian results by 5% to 9%; the level of agreement for gamma dose varies depending on the type of fuel, with UOX differing by the largest amount. The use of different gamma group structures and instantaneous versus asymptotic decay assumptions also complicate the comparison. For the calculation of dose rates from spent fuel in a shipping cask, the neutron source for UOX after 3-year cooling is within 1% and for MOX-W within 5% of one of the Russian results while the MOX-R difference is the largest at over 10%. These studies are a portion of the documentation required by the Russian nuclear regulatory authority, GAN, in order to certify Russian programs and data as being acceptably accurate for the analysis of mixed oxide fuels.

  13. Single-component routes to perovskite phase mixed metal oxides

    International Nuclear Information System (INIS)

    This paper reports that crystalline perovskite phase mixed metal oxides have been prepared at low temperatures from single-component mixed metal-organic precursors specifically designed for this purpose. Pyridine solutions of divalent metal α-hydroxycarboxylates of general empirical formula A(O2CMe2OH)2 where A = Pb, Ca, Sr, Ba: Me = methyl, react with metal alkoxide compounds such as B(OR')4, where B = Ti, Zr, Sn with the elimination of two equivalents of alcohol to form species with a fixed A:B stoichiometry of 1:1 according to the equation below. A(O2C(CMe2OH)2 + B(OR')4 > A(O2CCMe2O)2B(OR')2 + 2HOR'. Hydrolysis of these solutions with an excess of water results in homogeneous clear solutions from which white or pale yellow solids can be isolated, by evaporation of the volatile components in vacuo. Thermolysis at 350 degrees C in O2 resulted in formation of crystalline perovskite phase products for the representative examples PbTiO3, PbZrO3, BaTiO3 CaTiO3 and BaSnO3

  14. The melting behaviour of uranium/neptunium mixed oxides

    International Nuclear Information System (INIS)

    Highlights: • Melting temperatures in the (UO2 + NpO2) system have been measured by laser heating and fast pyrometry. • The melting behaviour of this system is satisfactorily described by an ideal solution model. • Raman spectroscopy demonstrates that blending and sintering of UO2 and NpO2 results in the formation of oxygen defects. • Addition of NpO2 to a UO2 matrix does not lead to significant chemical or thermal changes. - Abstract: The melting behaviour in the pseudo-binary system (UO2 + NpO2) has been studied experimentally for the first time in this work with the help of laser heating under controlled atmosphere. It has been observed that the solidus and liquidus lines of this system follow an ideal solution behaviour (negligible mixing enthalpy) between the well-established solid/liquid transition temperatures of pure UO2 (3130 K) and that recently assessed for NpO2 (T = 3070 K). Pre- and post-melting material characterizations performed with the help of X-ray diffraction and Raman spectroscopy are also consistent with ideal mixing of the two end members. Such behaviour follows the similar structure and bonding properties of tetravalent uranium and neptunium and the similar melting points of the two oxides. The interest of this investigation is twofold. From a technological viewpoint, it indicates that the incorporation of NpO2 in UO2 fuel or transmutation targets is a viable option to recycle neptunium without inducing any relevant change in the chemical or thermal stability of the uranium dioxide matrix, even up to the melting point. From a more fundamental perspective, it confirms that actinide dioxides, and particularly UO2, tend to mix in a way closer to ideal, the closer are the atomic numbers, 5-f electron shell filling, atomic radii and oxygen potentials of the metals forming the pure dioxides

  15. Applications of Metal/Mixed Metal Oxides as Photocatalyst: (A Review

    Directory of Open Access Journals (Sweden)

    Avnish Kumar Arora

    2016-08-01

    Full Text Available Metal oxides/ Mixed metal oxides have wide applications as catalyst, Adsorbents, Superconductors, semiconductors, ceramics, antifungal agents and also have spacious applications in medicines. This review article is focused on their applications as photocatalyst in various organic reactions.

  16. Methane combustion over lanthanum-based perovskite mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Arandiyan, Hamidreza [New South Wales Univ., Sydney (Australia). School of Chemical Engineering

    2015-11-01

    This book presents current research into the catalytic combustion of methane using perovskite-type oxides (ABO{sub 3}). Catalytic combustion has been developed as a method of promoting efficient combustion with minimum pollutant formation as compared to conventional catalytic combustion. Recent theoretical and experimental studies have recommended that noble metals supported on (ABO{sub 3}) with well-ordered porous networks show promising redox properties. Three-dimensionally ordered macroporous (3DOM) materials with interpenetrated and regular mesoporous systems have recently triggered enormous research activity due to their high surface areas, large pore volumes, uniform pore sizes, low cost, environmental benignity, and good chemical stability. These are all highly relevant in terms of the utilization of natural gas in light of recent catalytic innovations and technological advances. The book is of interest to all researchers active in utilization of natural gas with novel catalysts. The research covered comes from the most important industries and research centers in the field. The book serves not only as a text for researcher into catalytic combustion of methane, 3DOM perovskite mixed oxide, but also explores the field of green technologies by experts in academia and industry. This book will appeal to those interested in research on the environmental impact of combustion, materials and catalysis.

  17. Co-catalytic effect of Rh and Ru for the ethanol electro-oxidation in amorphous microparticulated alloys

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, Tamara C.; Pierna, Angel R.; Barroso, Javier [Dpto. de Ingenieria Quimica y del Medio Ambiente, Universidad del Pais Vasco, San Sebastian (Spain)

    2011-11-15

    The ethanol electro-oxidation on platinum catalyst in acid media leads to the formation of acetaldehyde and acetic acid as main products. Another problem is the poisoning of the electro-catalyst surface with CO formed during the fuel oxidation reaction. To increase the performance of Direct Ethanol Fuel Cells (DEFCs) it is necessary to develop new electrode materials or modification of the existing Pt catalysts. This work presents the electrochemical response to ethanol and CO oxidation of different compositional amorphous alloys obtained by ball milling technique, used as electrodes. Alloys with Ni{sub 59}Nb{sub 40}Pt{sub 0.6}Rh{sub 0.4} and Ni{sub 59}Nb{sub 40}Pt{sub 0.6}Rh{sub 0.2}Ru{sub 0.2} composi-tions were studied. The current density towards ethanol oxidation decreases with the presence of ruthenium; however, this electrode shows the best tolerance to CO, with lower surface coverage (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Impact of soft annealing on the performance of solution-processed amorphous zinc tin oxide thin-film transistors

    KAUST Repository

    Nayak, Pradipta K.

    2013-05-08

    It is demonstrated that soft annealing duration strongly affects the performance of solution-processed amorphous zinc tin oxide thin-film transistors. Prolonged soft annealing times are found to induce two important changes in the device: (i) a decrease in zinc tin oxide film thickness, and (ii) an increase in oxygen vacancy concentration. The devices prepared without soft annealing exhibited inferior transistor performances, in comparison to devices in which the active channel layer (zinc tin oxide) was subjected to soft annealing. The highest saturation field-effect mobility - 5.6 cm2 V-1 s-1 with a drain-to-source on-off current ratio (Ion/Ioff) of 2 × 108 - was achieved in the case of devices with 10-min soft-annealed zinc tin oxide thin films as the channel layer. The findings of this work identify soft annealing as a critical parameter for the processing of chemically derived thin-film transistors, and it correlates device performance to the changes in material structure induced by soft annealing. © 2013 American Chemical Society.

  19. The role of oxide interlayers in back reflector configurations for amorphous silicon solar cells

    NARCIS (Netherlands)

    Demontis, V.; Sanna, C.; Melskens, J.; Santbergen, R.; Smets, A.H.M.; Damiano, A.; Zeman, M.

    2013-01-01

    Thin oxide interlayers are commonly added to the back reflector of thin-film silicon solar cells to increase their current. To gain more insight in the enhancement mechanism, we tested different back reflector designs consisting of aluminium-doped zinc oxide (ZnO:Al) and/or hydrogenated silicon oxid

  20. Synthesis and characterization of uranium-americium mixed oxides

    International Nuclear Information System (INIS)

    Americium isotopes represent a significant part of high-level and long-lived nuclear waste in spent fuels. Among the envisaged reprocessing scenarios, their transmutation in fast neutron reactors using uranium-americium mixed-oxide pellets (U1-xAmxO2±δ) is a promising option which would help decrease the ecological footprint of ultimate waste repository sites. In this context, this thesis is dedicated to the study of such compounds over a wide range of americium contents (7.5 at.% ≤ Am/(U+Am) ≤ 70 at.%), with an emphasis on their fabrication from single-oxide precursors and the assessment of their structural and thermodynamic stabilities, also taking self-irradiation effects into account. Results highlight the main influence of americium reduction to Am(+III), not only on the mechanisms of solid-state formation of the U1-xAmxO2±δ solid solution, but also on the stabilization of oxidized uranium cations and the formation of defects in the oxygen sublattice such as vacancies and cub-octahedral clusters. In addition, the data acquired concerning the stability of U1-xAmxO2±δ compounds (existence of a miscibility gap, vaporization behavior) were compared to calculations based on new thermodynamic modelling of the U-Am-O ternary system. Finally, α-self-irradiation-induced structural effects on U1-xAmxO2±δ compounds were analyzed using XRD, XAS and TEM, allowing the influence of americium content on the structural swelling to be studied as well as the description of the evolution of radiation-induced structural defects. (author)

  1. Synthesis of amorphous zirconium oxide with luminescent characteristics; Sintesis de oxido de circonio amorfo con caracteristicas luminiscentes

    Energy Technology Data Exchange (ETDEWEB)

    Barrera S, M.; Chavez G, M.; Soto E, A.M.; Velasquez O, C.; Garcia S, M.A.; Olvera T, L.; Rivera M, T. [UAM-I, 09340 Mexico D.F. (Mexico)

    2004-07-01

    It was prepared zirconium oxide, ZrO{sub 2}, by means of hydrolysis-condensation reactions (sol-gel method), using zirconium propoxide, Zr(C{sub 3}H{sub 7}O){sub 4}, as precursor and nitric acid, HNO{sub 3}, as catalyst of the hydrolysis reaction. In this synthesis it was used a molar ratio water-alkoxide, r=n{sub H2O}/n{sub Zr}(C{sub 3}H{sub 7}0){sub 4}, high, similar to 200, so that the hydrolysis happens quickly and the nucleation and growth are completed in very little time. The solid was characterized with Ftir spectrophotometry, Differential thermal analysis (Dta), Thermal gravimetric analysis (T G), X-ray diffraction of powders, Scanning electron microscopy (Sem) and X-ray Dispersion energy (EDX). The ZrO{sub 2} obtained by this way is amorphous even to 300 C and it consists of big aggregates. The amorphous ZrO{sub 2}, presents thermoluminescent behavior, after it was irradiated with UV radiation and beta particles of {sup 90}Sr/{sup 90}Y and it was thermally stimulated. (Author)

  2. Crystallization behavior of amorphous indium-gallium-zinc-oxide films and its effects on thin-film transistor performance

    Science.gov (United States)

    Suko, Ayaka; Jia, JunJun; Nakamura, Shin-ichi; Kawashima, Emi; Utsuno, Futoshi; Yano, Koki; Shigesato, Yuzo

    2016-03-01

    Amorphous indium-gallium-zinc oxide (a-IGZO) films were deposited by DC magnetron sputtering and post-annealed in air at 300-1000 °C for 1 h to investigate the crystallization behavior in detail. X-ray diffraction, electron beam diffraction, and high-resolution electron microscopy revealed that the IGZO films showed an amorphous structure after post-annealing at 300 °C. At 600 °C, the films started to crystallize from the surface with c-axis preferred orientation. At 700-1000 °C, the films totally crystallized into polycrystalline structures, wherein the grains showed c-axis preferred orientation close to the surface and random orientation inside the films. The current-gate voltage (Id-Vg) characteristics of the IGZO thin-film transistor (TFT) showed that the threshold voltage (Vth) and subthreshold swing decreased markedly after the post-annealing at 300 °C. The TFT using the totally crystallized films also showed the decrease in Vth, whereas the field-effect mobility decreased considerably.

  3. Melting behavior of mixed U-Pu oxides under oxidizing conditions

    Science.gov (United States)

    Strach, Michal; Manara, Dario; Belin, Renaud C.; Rogez, Jacques

    2016-05-01

    In order to use mixed U-Pu oxide ceramics in present and future nuclear reactors, their physical and chemical properties need to be well determined. The behavior of stoichiometric (U,Pu)O2 compounds is relatively well understood, but the effects of oxygen stoichiometry on the fuel performance and stability are often still obscure. In the present work, a series of laser melting experiments were carried out to determine the impact of an oxidizing atmosphere, and in consequence the departure from a stoichiometric composition on the melting behavior of six mixed uranium plutonium oxides with Pu content ranging from 14 to 62 wt%. The starting materials were disks cut from sintered stoichiometric pellets. For each composition we have performed two laser melting experiments in pressurized air, each consisting of four shots of different duration and intensity. During the experiments we recorded the temperature at the surface of the sample with a pyrometer. Phase transitions were qualitatively identified with the help of a reflected blue laser. The observed phase transitions occur at a systematically lower temperature, the lower the Pu content of the studied sample. It is consistent with the fact that uranium dioxide is easily oxidized at elevated temperatures, forming chemical species rich in oxygen, which melt at a lower temperature and are more volatile. To our knowledge this campaign is a first attempt to quantitatively determine the effect of O/M on the melting temperature of MOX.

  4. Preliminary comparison of three processes of AlN oxidation: dry, wet and mixed ones

    Directory of Open Access Journals (Sweden)

    Korbutowicz R.

    2016-03-01

    Full Text Available Three methods of AlN layers oxidation: dry, wet and mixed (wet with oxygen were compared. Some physical parameters of oxidized thin films of aluminum nitride (AlN layers grown on silicon Si(1 1 1 were investigated by means Energy-Dispersive X-ray Spectroscopy (EDS and Spectroscopic Ellipsometry (SE. Three series of the thermal oxidations processes were carried out at 1012 °C in pure nitrogen as carrying gas and various gas ambients: (a dry oxidation with oxygen, (b wet oxidation with water steam and (c mixed atmosphere with various process times. All the research methods have shown that along with the rising of the oxidation time, AlN layer across the aluminum oxide nitride transforms to aluminum oxide. The mixed oxidation was a faster method than the dry or wet ones.

  5. Improved characteristics of amorphous indium-gallium-zinc-oxide-based resistive random access memory using hydrogen post-annealing

    Science.gov (United States)

    Kang, Dae Yun; Lee, Tae-Ho; Kim, Tae Geun

    2016-08-01

    The authors report an improvement in resistive switching (RS) characteristics of amorphous indium-gallium-zinc-oxide (a-IGZO)-based resistive random access memory devices using hydrogen post-annealing. Because this a-IGZO thin film has oxygen off-stoichiometry in the form of deficient and excessive oxygen sites, the film properties can be improved by introducing hydrogen atoms through the annealing process. After hydrogen post-annealing, the device exhibited a stable bipolar RS, low-voltage set and reset operation, long retention (>105 s), good endurance (>106 cycles), and a narrow distribution in each current state. The effect of hydrogen post-annealing is also investigated by analyzing the sample surface using X-ray photon spectroscopy and atomic force microscopy.

  6. High performance solution-deposited amorphous indium gallium zinc oxide thin film transistors by oxygen plasma treatment

    KAUST Repository

    Nayak, Pradipta K.

    2012-05-16

    Solution-deposited amorphous indium gallium zinc oxide (a-IGZO) thin film transistors(TFTs) with high performance were fabricated using O2-plasma treatment of the films prior to high temperature annealing. The O2-plasma treatment resulted in a decrease in oxygen vacancy and residual hydrocarbon concentration in the a-IGZO films, as well as an improvement in the dielectric/channel interfacial roughness. As a result, the TFTs with O2-plasma treated a-IGZO channel layers showed three times higher linear field-effect mobility compared to the untreated a-IGZO over a range of processing temperatures. The O2-plasma treatment effectively reduces the required processing temperature of solution-deposited a-IGZO films to achieve the required performance.

  7. Surface reactivity and oxygen migration in amorphous indium-gallium-zinc oxide films annealed in humid atmosphere

    International Nuclear Information System (INIS)

    An isotope tracer study, i.e., 18O/16O exchange using 18O2 and H218O, was performed to determine how post-deposition annealing (PDA) affected surface reactivity and oxygen diffusivity of amorphous indium–gallium–zinc oxide (a-IGZO) films. The oxygen tracer diffusivity was very high in the bulk even at low temperatures, e.g., 200 °C, regardless of PDA and exchange conditions. In contrast, the isotope exchange rate, dominated by surface reactivity, was much lower for 18O2 than for H218O. PDA in a humid atmosphere at 400 °C further suppressed the reactivity of O2 at the a-IGZO film surface, which is attributable to –OH-terminated surface formation

  8. Suppression of photo-bias induced instability for amorphous indium tungsten oxide thin film transistors with bi-layer structure

    Science.gov (United States)

    Liu, Po-Tsun; Chang, Chih-Hsiang; Chang, Chih-Jui

    2016-06-01

    This study investigates the instability induced by bias temperature illumination stress (NBTIS) for an amorphous indium-tungsten-oxide thin film transistor (a-IWO TFT) with SiO2 backchannel passivation layer (BPL). It is found that this electrical degradation phenomenon can be attributed to the generation of defect states during the BPL process, which deteriorates the photo-bias stability of a-IWO TFTs. A method proposed by adding an oxygen-rich a-IWO thin film upon the a-IWO active channel layer could effectively suppress the plasma damage to channel layer during BPL deposition process. The bi-layer a-IWO TFT structure with an oxygen-rich back channel exhibits superior electrical reliability of device under NBTIS.

  9. Large scale integration of flexible non-volatile, re-addressable memories using P(VDF-TrFE) and amorphous oxide transistors

    NARCIS (Netherlands)

    Gelinck, G.H.; Cobb, B.; Breemen, A.J.J.M. van; Myny, K.

    2015-01-01

    Ferroelectric polymers and amorphous metal oxide semiconductors have emerged as important materials for re-programmable non-volatile memories and high-performance, flexible thin-film transistors, respectively. However, realizing sophisticated transistor memory arrays has proven to be a challenge, an

  10. Thermal Transport in Graphene Oxide – From Ballistic Extreme to Amorphous Limit

    OpenAIRE

    Xin Mu; Xufei Wu; Teng Zhang; Go, David B.; Tengfei Luo

    2014-01-01

    Graphene oxide is being used in energy, optical, electronic and sensor devices due to its unique properties. However, unlike its counterpart – graphene – the thermal transport properties of graphene oxide remain unknown. In this work, we use large-scale molecular dynamics simulations with reactive potentials to systematically study the role of oxygen adatoms on the thermal transport in graphene oxide. For pristine graphene, highly ballistic thermal transport is observed. As the oxygen coverag...

  11. Eco-friendly synthesis and characterization of Ni-Si nanoparticles mixed oxides as catalyst for partial oxidation of methane

    International Nuclear Information System (INIS)

    The nanoparticles of Ni-Si mixed oxides were prepared by co-precipitation method using nickel nitrate; Ni(NO3)2 6H2O and tetraethyl orthosilicate. The products were characterized by X-ray diffraction, transmission electron microscopy, and hydrogen temperature program reduction (H2-TPR). The results revealed that Ni-Si mixed oxides particles were obtained with average particle size 1-2 nm. The Ni-Si nanoparticles mixed oxides successfully catalyzed the partial oxidation of methane to hydrogen and carbon monoxide (Syn gas) using a fixed-bed reactor with about 92% activity and high selectivity. No coke formation and deactivation of catalyst were observed during the course of reaction. Particularly significant is the similar reactivity of this catalyst with that of Ni-Ce-Zr mixed oxides

  12. Selective oxidation of propane to acrylic acid over mixed metal oxide catalysts

    Institute of Scientific and Technical Information of China (English)

    Wei Zheng; Zhenxing Yu; Ping Zhang; Yuhang Zhang; Hongying Fu; Xiaoli Zhang; Qiquan Sun; Xinguo Hu

    2008-01-01

    The effects of metal atomic ratio, water content, oxygen content, and calcination temperature on the catalytic perfor-mances of MoVTeNbO mixed oxide catalyst system for the selective oxidation of propane to acrylic acid have been investigated and discussed. Among the catalysts studied, it was found that the MoVTeNbO catalyst calcined at a temperature of 600 ℃ showed the best performance in terms of propane conversion and selectivity for acrylic acid under an atmosphere of nitrogen. An effective MoVTeNbO oxide catalyst for propane selective oxidation to acrylic acid was obtained with a combination of a preferred metal atomic ratio (Mo1 V0.31Te0.23Nb0.12). The optimum reaction condition for the selective oxidation of propane was the molar ratio of C3H81 :O2 : H2O : N1 = 4.4 : 12.8 : 15.3 : 36.9. Under such conditions, the conversion of propane and the maximum yield of acrylic acid reached about 50% and 21%, respectively.

  13. Effects of calcium and phosphate on uranium(IV) oxidation. Comparison between nanoparticulate uraninite and amorphous UIV–phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Latta, Drew E. [Argonne National Lab. (ANL), Argonne, IL (United States); Kemner, Kenneth M. [Argonne National Lab. (ANL), Argonne, IL (United States); Mishra, Bhoopesh [Argonne National Lab. (ANL), Argonne, IL (United States); Illinois Inst. of Technology, Chicago, IL (United States); Boyanov, Maxim I. [Argonne National Lab. (ANL), Argonne, IL (United States); Bulgarian Academy of Sciences, Sofia (Bulgaria)

    2016-02-01

    The mobility of uranium in subsurface environments depends strongly on its redox state, with UIV phases being significantly less soluble than UVI minerals. This study compares the oxidation kinetics and mechanisms of two potential products of UVI reduction in natural systems, a nanoparticulate UO2 phase and an amorphous UIV–Ca–PO4 analog to ningyoite (CaUIV(PO4)2·1–2H2O). The valence of U was tracked by X-ray absorption near-edge spectroscopy (XANES), showing similar oxidation rate constants for UIVO2 and UIV–phosphate in solutions equilibrated with atmospheric O2 and CO2 at pH 7.0 (kobs,UO2 = 0.17 ± 0.075 h-1 vs. kobs,UIVPO4 = 0.30 ± 0.25 h-1). Addition of up to 400 μM Ca and PO4 decreased the oxidation rate constant by an order of magnitude for both UO2 and UIV–phosphate. The intermediates and products of oxidation were tracked by electron microscopy, powder X-ray diffraction (pXRD), and extended X-ray absorption fine-structure spectroscopy (EXAFS). In the absence of Ca or PO4, the product of UO2 oxidation is Na–uranyl oxyhydroxide (under environmentally relevant concentrations of sodium, 15 mM NaClO4 and low carbonate concentration), resulting in low concentrations of dissolved UVI (<2.5 × 10-7 M). Oxidation of UIV–phosphate produced a Na-autunite phase (Na2(UO2)PO4·xH2O), resulting in similarly low dissolved U concentrations (<7.3 × 10-8 M). When Ca and PO4 are present in the solution, the EXAFS data and the solubility of the UVI phase resulting from oxidation of UO2 and UIV–phosphate are consistent with the precipitation of Na-autunite. Bicarbonate extractions and Ca K-edge X-ray absorption spectroscopy of oxidized solids indicate the formation of a Ca–UVI–PO4 layer on the UO2 surface and suggest a passivation layer mechanism for the decreased rate of UO2 oxidation in the presence of Ca and PO4. Interestingly, the extractions were unable to remove all of the oxidized U from partially oxidized UO2 solids, suggesting that oxidized U is

  14. Effects of calcium and phosphate on uranium(IV) oxidation: Comparison between nanoparticulate uraninite and amorphous UIV-phosphate

    Science.gov (United States)

    Latta, Drew E.; Kemner, Kenneth M.; Mishra, Bhoopesh; Boyanov, Maxim I.

    2016-02-01

    The mobility of uranium in subsurface environments depends strongly on its redox state, with UIV phases being significantly less soluble than UVI minerals. This study compares the oxidation kinetics and mechanisms of two potential products of UVI reduction in natural systems, a nanoparticulate UO2 phase and an amorphous UIV-Ca-PO4 analog to ningyoite (CaUIV(PO4)2·1-2H2O). The valence of U was tracked by X-ray absorption near-edge spectroscopy (XANES), showing similar oxidation rate constants for UIVO2 and UIV-phosphate in solutions equilibrated with atmospheric O2 and CO2 at pH 7.0 (kobs,UO2 = 0.17 ± 0.075 h-1 vs. kobs,UIVPO4 = 0.30 ± 0.25 h-1). Addition of up to 400 μM Ca and PO4 decreased the oxidation rate constant by an order of magnitude for both UO2 and UIV-phosphate. The intermediates and products of oxidation were tracked by electron microscopy, powder X-ray diffraction (pXRD), and extended X-ray absorption fine-structure spectroscopy (EXAFS). In the absence of Ca or PO4, the product of UO2 oxidation is Na-uranyl oxyhydroxide (under environmentally relevant concentrations of sodium, 15 mM NaClO4 and low carbonate concentration), resulting in low concentrations of dissolved UVI (<2.5 × 10-7 M). Oxidation of UIV-phosphate produced a Na-autunite phase (Na2(UO2)PO4·xH2O), resulting in similarly low dissolved U concentrations (<7.3 × 10-8 M). When Ca and PO4 are present in the solution, the EXAFS data and the solubility of the UVI phase resulting from oxidation of UO2 and UIV-phosphate are consistent with the precipitation of Na-autunite. Bicarbonate extractions and Ca K-edge X-ray absorption spectroscopy of oxidized solids indicate the formation of a Ca-UVI-PO4 layer on the UO2 surface and suggest a passivation layer mechanism for the decreased rate of UO2 oxidation in the presence of Ca and PO4. Interestingly, the extractions were unable to remove all of the oxidized U from partially oxidized UO2 solids, suggesting that oxidized U is distributed between

  15. High mechanical endurance RRAM based on amorphous gadolinium oxide for flexible nonvolatile memory application

    Science.gov (United States)

    Zhao, Hongbin; Tu, Hailing; Wei, Feng; Shi, Zhitian; Xiong, Yuhua; Zhang, Yan; Du, Jun

    2015-05-01

    In this paper, we use amorphous Gd2O3 as the switching layer for fabricated RRAM devices with novel high performance, excellent flexibility, and mechanical endurance properties as potential candidate memory for flexible electronics applications. The obtained Cu/Gd2O3/Pt devices on flexible polyethylene terephthalate (PET) substrates show bipolar switching characteristics, low voltage operation (106 s). No performance degradation occurs, and the stored information is not lost after the device has been bent to different angles and up to 104 times in the bending tests. Based on temperature-dependent switching characteristics, the formation of Cu conducting filaments stemming from electrochemical reactions is believed to be the reason for the resistance switching from a high resistance state to a low resistance state. The studies of the integrated experiment and mechanism lay the foundation for the development of high-performance flexible RRAM.

  16. Amorphous indium gallium zinc oxide thin film grown by pulse laser deposition technique

    Science.gov (United States)

    Mistry, Bhaumik V.; Joshi, U. S.

    2016-05-01

    Highly electrically conducting and transparent in visible light IGZO thin film were grown on glass substrate at substrate temperature of 400 C by a pulse laser deposition techniques. Structural, surface, electrical, and optical properties of IGZO thin films were investigated at room temperature. Smooth surface morphology and amorphous nature of the film has been confirmed from the AFM and GIXRD analysis. A resistivity down to 7.7×10-3 V cm was reproducibly obtained while maintaining optical transmission exceeding 70% at wavelengths from 340 to 780 nm. The carrier densities of the film was obtain to the value 1.9×1018 cm3, while the Hall mobility of the IGZO thin film was 16 cm2 V-1S-1.

  17. Surface modification of zinc oxide nanoparticles with amorphous silica alters their fate in the circulation.

    Science.gov (United States)

    Konduru, Nagarjun V; Murdaugh, Kimberly M; Swami, Archana; Jimenez, Renato J; Donaghey, Thomas C; Demokritou, Philip; Brain, Joseph D; Molina, Ramon M

    2016-08-01

    Nanoparticle (NP) pharmacokinetics and biological effects are influenced by many factors, especially surface physicochemical properties. We assessed the effects of an amorphous silica coating on the fate of zinc after intravenous (IV) injection of neutron activated uncoated (65)ZnO or silica-coated (65)ZnO NPs in male Wistar Han rats. Groups of IV-injected rats were sequentially euthanized, and 18 tissues were collected and analyzed for (65)Zn radioactivity. The protein coronas on each ZnO NP after incubation in rat plasma were analyzed by SDS-PAGE gel electrophoresis and mass spectrometry of selected gel bands. Plasma clearance for both NPs was biphasic with rapid initial and slower terminal clearance rates. Half-lives of plasma clearance of silica-coated (65)ZnO were shorter (initial - <1 min; terminal - 2.5 min) than uncoated (65)ZnO (initial - 1.9 min; terminal - 38 min). Interestingly, the silica-coated (65)ZnO group had higher (65)Zn associated with red blood cells and higher initial uptake in the liver. The (65)Zn concentrations in all the other tissues were significantly lower in the silica-coated than uncoated groups. We also found that the protein corona formed on silica-coated ZnO NPs had higher amounts of plasma proteins, particularly albumin, transferrin, A1 inhibitor 3, α-2-hs-glycoprotein, apoprotein E and α-1 antitrypsin. Surface modification with amorphous silica alters the protein corona, agglomerate size, and zeta potential of ZnO NPs, which in turn influences ZnO biokinetic behavior in the circulation. This emphasizes the critical role of the protein corona in the biokinetics, toxicology and nanomedical applications of NPs. PMID:26581431

  18. Mixed titanium, silicon, and aluminum oxide nanostructures as novel adsorbent for removal of rhodamine 6G and methylene blue as cationic dyes from aqueous solution.

    Science.gov (United States)

    Pal, Umapada; Sandoval, Alberto; Madrid, Sergio Isaac Uribe; Corro, Grisel; Sharma, Vivek; Mohanty, Paritosh

    2016-11-01

    Mixed oxide nanoparticles containing Ti, Si, and Al of 8-15 nm size range were synthesized using a combined sol-gel - hydrothermal method. Effects of composition on the structure, morphology, and optical properties of the nanoparticles were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), microRaman spectroscopy, and diffuse reflectance spectroscopy (DRS). Dye removal abilities of the nanoparticles from aqueous solutions were tested for different cationic dyes. While all the mixed oxide nanoparticles revealed high and fast adsorption of cationic dyes, the particles containing Ti and Si turned out to be the best. The adsorption kinetics and equilibrium adsorption behavior of the adsorbate - adsorbent systems could be well described by pseudo-second-order kinetics and Langmuir isotherm model, respectively. Estimated thermodynamic parameters revealed the adsorption process is spontaneous, driven mainly by the electrostatic force between the cationic dye molecules and negative charge at nanoparticle surface. Highest dye adsorption capacity (162.96 mg MB/g) of the mixed oxide nanostructures containing Ti and Si is associated to their high specific surface area, and the presence of surface Si-O(δ-) groups, in addition to the hydroxyl groups of amorphous titania. Mixed oxide nanoparticles containing 75% Ti and 25% Si seen to be the most efficient adsorbents for removing cationic dye molecules from wastewater. PMID:27529381

  19. Kinetics of gaseous atoms in uranium plutonium mixed oxide

    International Nuclear Information System (INIS)

    The kinetics of fission gas atoms in nuclear fuel are much different from those discussed in academic fields such as statistical mechanics and/or statistical thermodynamics established by Ludwig Boltzmann. The field of movement should have unique microstructure such as pore, grain boundary, and especially plutonium enriched zone (Pu spot) in case of Uranium Plutonium Mixed Oxide (MOX). The mechanism of fission gas release has been studied by many researchers for these nearly fifty years since Booth first set down the simple approximations to fission gas release from irradiated UO2. However, there is still no general agreement what mechanisms are responsible for observed coalescence of intergranular bubbles during their growth. It might be due to the complexity of the kinetics of gaseous atoms in nuclear fuel pellet having unique microstructure, temperature gradient and irradiation damage. The objectives of this paper are to introduce brief review of fundamental process of kinetics of gaseous atom in nuclear fuel and to develop effective fission gas release model. The fission gas release mechanism for MOX fuel which has heterogeneous microstructure including Pu spot is introduced based on the result of post-irradiation examination with MOX having high plutonium content. (authors)

  20. Co-Al Mixed Oxides Prepared via LDH Route Using Microwaves or Ultrasound: Application for Catalytic Toluene Total Oxidation

    Directory of Open Access Journals (Sweden)

    Eric Genty

    2015-05-01

    Full Text Available Co6Al2HT hydrotalcite-like compounds were synthesized by three different methods: co-precipitation, microwaves-assisted and ultrasound-assisted methods. The mixed oxides obtained after calcination were studied by several techniques: XRD, TEM, H2-TPR and XPS. They were also tested as catalysts in the reaction of total oxidation of toluene. The physico-chemical studies revealed a modification of the structural characteristics (surface area, morphology as well as of the reducibility of the formed mixed oxides. The solid prepared by microwaves-assisted synthesis was the most active. Furthermore, a relationship between the ratio of Co2+ on the surface, the reducibility of the Co-Al mixed oxide and the T50 in toluene oxidation was demonstrated. This suggests a Mars Van Krevelen mechanism for toluene total oxidation on these catalysts.

  1. Widely bandgap tunable amorphous Cd-Ga-O oxide semiconductors exhibiting electron mobilities ≥10 cm2 V-1 s-1

    Science.gov (United States)

    Yanagi, Hiroshi; Sato, Chiyuki; Kimura, Yota; Suzuki, Issei; Omata, Takahisa; Kamiya, Toshio; Hosono, Hideo

    2015-02-01

    Amorphous oxide semiconductors exhibit large electron mobilities; however, their bandgaps are either too large for solar cells or too small for deep ultraviolet applications depending on the materials system. Herein, we demonstrate that amorphous Cd-Ga-O semiconductors display bandgaps covering the entire 2.5-4.3 eV region while maintaining large electron mobilities ≥10 cm2 V-1 s-1. The band alignment diagram obtained by ultraviolet photoemission spectroscopy and the bandgap values reveal that these semiconductors form type-II heterojunctions with p-type Cu2O, which is suitable for solar cells and solar-blind ultraviolet sensors.

  2. Sol-gel derived oxides and mixed oxides catalysts with narrow mesoporous distribution

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A novel sol-gel process for preparing oxides and mixed oxides sols from precipitation and peptization process is reported in this article. Inorganic salts are used as raw materials in this study. It is found that the amount of acid has great influence on the stability and particle diameter distribution of the precursor sols. Ultrasonic treatment is used to prepare alumina sol at room temperature. The result of 27Al NMR shows that there exist Al137+ species in the sol. By controlling the sol particles with narrow particle diameter distribution, alumina, titania and silica-alumina (SA) materials with narrow mesoporous distribution are formed by regular packing of sol particles during gelation without using any templates. The results also show that the structure and particle diameter distribution of precursor sol determine the final materials' texture.

  3. Revisiting Oxidative Dehydrogenation of Ethane by W Doping into MoVMn Mixed Oxides at Low Temperature

    Directory of Open Access Journals (Sweden)

    Mohammed H. Al-Hazmi

    2015-01-01

    Full Text Available The catalytic performance of MoVMnW mixed oxides was investigated in the oxidative dehydrogenation of ethane at three different reaction temperatures (235, 255, and 275°C using oxygen as an oxidant. The catalysts were characterized by using X-ray diffraction, temperature-programmed reduction, and scanning electron microscopy. The MoVMnW mixed oxide catalyst showed the 70–90% of ethylene selectivity at the reaction temperatures. However, a significant decrease in the selectivity of ethylene was observed by increasing the reaction temperature from 235°C to 275°C.

  4. The spectrographic analysis of plutonium oxide or mixed plutonium oxide/uranium oxide fuel pellets by the dried residue technique

    International Nuclear Information System (INIS)

    An emission spectrographic method for the quantitative determination of metallic impurities in plutonium oxide and mixed plutonium oxide/uranium oxide is described. The fuel is dissolved in nitric acid and the plutonium and/or uranium extracted with tributyl phosphate. A small aliquot of the aqueous residue is dried on a 'mini' pyrolitic graphite plate and excited by high voltage AC spark in an oxygen atmosphere. Spectra are recorded in a region which has been specially selected to record simultaneously lines of boron and cadmium in the 2nd order and all the other elements of interest in the 1st order. Indium is used as an internal standard. The excitation of very small quantities of the uraniumm/plutonium free residue by high voltage spark, together with three separate levels of containment reduce the hazards to personnel and the environment to a minimum with limited effect on sensitivity and accuracy of the results. (auth)

  5. A transparent diode with high rectifying ratio using amorphous indium-gallium-zinc oxide/SiNx coupled junction

    International Nuclear Information System (INIS)

    We introduce a transparent diode that shows both high rectifying ratio and low leakage current at process temperature below 250 °C. This device is clearly distinguished from all previous transparent diodes in that the rectifying behavior results from the junction between a semiconductor (amorphous indium-gallium-zinc oxide (a-IGZO)) and insulator (SiNx). We systematically study the properties of each junction within the device structure and demonstrate that the a-IGZO/SiNx junction is the source of the outstanding rectification. The electrical characteristics of this transparent diode are: 2.8 A/cm2 on-current density measured at −7 V; lower than 7.3 × 10−9 A/cm2 off-current density; 2.53 ideality factor; and high rectifying ratio of 108–109. Furthermore, the diode structure has a transmittance of over 80% across the visible light range. The operating principle of the indium-tin oxide (ITO)/a-IGZO/SiNx/ITO device was examined with an aid of the energy band diagram and we propose a preliminary model for the rectifying behavior. Finally, we suggest further directions for research on this transparent diode

  6. Interface Study on Amorphous Indium Gallium Zinc Oxide Thin Film Transistors Using High-k Gate Dielectric Materials

    Directory of Open Access Journals (Sweden)

    Yu-Hsien Lin

    2015-01-01

    Full Text Available We investigated amorphous indium gallium zinc oxide (a-IGZO thin film transistors (TFTs using different high-k gate dielectric materials such as silicon nitride (Si3N4 and aluminum oxide (Al2O3 at low temperature process (<300°C and compared them with low temperature silicon dioxide (SiO2. The IGZO device with high-k gate dielectric material will expect to get high gate capacitance density to induce large amount of channel carrier and generate the higher drive current. In addition, for the integrating process of integrating IGZO device, postannealing treatment is an essential process for completing the process. The chemical reaction of the high-k/IGZO interface due to heat formation in high-k/IGZO materials results in reliability issue. We also used the voltage stress for testing the reliability for the device with different high-k gate dielectric materials and explained the interface effect by charge band diagram.

  7. Comparison of the electrical and optical properties of direct current and radio frequency sputtered amorphous indium gallium zinc oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Jianke, E-mail: yaojk@pkusz.edu.cn [School of Computer and Information Engineering, Shenzhen Graduate School of Peking University, Shenzhen 518055 (China); Gong, Li [Instrumental Analysis and Research Center, Sun Yat-Sen University, Guangzhou 10275 (China); Xie, Lei [School of Computer and Information Engineering, Shenzhen Graduate School of Peking University, Shenzhen 518055 (China); Zhang, Shengdong, E-mail: zhangsd@pku.edu.cn [School of Computer and Information Engineering, Shenzhen Graduate School of Peking University, Shenzhen 518055 (China); Institute of Microelectronics, Peking University, Beijing 100871 (China)

    2013-01-01

    The electrical and optical properties of direct current and radio frequency (RF) sputtered amorphous indium gallium zinc oxide (a-IGZO) films are compared. It is found that the RF sputtered a-IGZO films have better stoichiometry (In:Ga:Zn:O = 1:1:1:2.5–3.0), lower electrical conductivity (σ < 8 S/cm), higher refractive index (n = 1.9–2.0) and larger band gap (E{sub g} = 3.02–3.29 eV), and show less shift of Fermi level (△ E{sub F} ∼ 0.26 eV) and increased concentration of electrons (△ N{sub e} ∼ 10{sup 4}) in the conduction band with the reduction concentration of oxygen vacancy (V{sub O}). Although a-IGZO has intensively been studied for a semiconductor channel material of thin film transistors in next-generation flat panel displays, its fundamental material parameters have not been thoroughly reported. In this work, the work function (φ) of a-IGZO films is tested with the ultraviolet photoelectron spectroscopy. It is found that the φ of a-IGZO films is in the range of 4.0–5.0 eV depending on the V{sub O}. - Highlights: ► Amorphous InGaZnO{sub 4} (a-IGZO) films were prepared with different sputtering modes. ► Electrical and optical properties of the different films were compared. ► Fermi level (△E{sub F}) shift in a-IGZO films were tested by X-ray photoelectron spectroscopy. ► The relation of △E{sub F} with the properties of a-IGZO films were discussed. ► Work function was tested by ultraviolet photoelectron spectroscopy.

  8. Comparison of the electrical and optical properties of direct current and radio frequency sputtered amorphous indium gallium zinc oxide films

    International Nuclear Information System (INIS)

    The electrical and optical properties of direct current and radio frequency (RF) sputtered amorphous indium gallium zinc oxide (a-IGZO) films are compared. It is found that the RF sputtered a-IGZO films have better stoichiometry (In:Ga:Zn:O = 1:1:1:2.5–3.0), lower electrical conductivity (σ < 8 S/cm), higher refractive index (n = 1.9–2.0) and larger band gap (Eg = 3.02–3.29 eV), and show less shift of Fermi level (△ EF ∼ 0.26 eV) and increased concentration of electrons (△ Ne ∼ 104) in the conduction band with the reduction concentration of oxygen vacancy (VO). Although a-IGZO has intensively been studied for a semiconductor channel material of thin film transistors in next-generation flat panel displays, its fundamental material parameters have not been thoroughly reported. In this work, the work function (φ) of a-IGZO films is tested with the ultraviolet photoelectron spectroscopy. It is found that the φ of a-IGZO films is in the range of 4.0–5.0 eV depending on the VO. - Highlights: ► Amorphous InGaZnO4 (a-IGZO) films were prepared with different sputtering modes. ► Electrical and optical properties of the different films were compared. ► Fermi level (△EF) shift in a-IGZO films were tested by X-ray photoelectron spectroscopy. ► The relation of △EF with the properties of a-IGZO films were discussed. ► Work function was tested by ultraviolet photoelectron spectroscopy

  9. Study of oxidation behaviour of Zr-based bulk amorphous alloy Zr65Cu17.5Ni10Al7.5 by thermogravimetric analyser

    Indian Academy of Sciences (India)

    A Dhawan; K Raetzke; F Faupel; S K Sharma

    2001-06-01

    The oxidation behaviour of Zr-based bulk amorphous alloy Zr65Cu17.5Ni10Al7.5 has been studied in air environment at various temperatures in the temperature range 591–684 K using a thermogravimetric analyser (TGA). The oxidation kinetics of the alloy in the amorphous phase obeys the parabolic rate law for oxidation in the temperature range 591–664 K. The values of the activation energy and pre-factor as calculated from the Arrhenius temperature dependence of the rate constants have been found to be 1.80 eV and 2.12 × 109 g cm–2.sec–1/2, respectively.

  10. Oxidative stabilization of mixed mayonnaises made with linseed oil and saturated medium-chain triglyceride oil

    DEFF Research Database (Denmark)

    Raudsepp, Piret; Brüggemann, Dagmar A.; Lenferink, Aufried;

    2014-01-01

    Mayonnaises, made with either saturated medium chain triglyceride (MCT) oil or unsaturated purified linseed oil (LSO), were mixed. Raman confocal microspectrometry demonstrated that lipid droplets in mixed mayonnaise remained intact containing either MCT oil or LSO. Peroxide formation during...... simply diluting unsaturated triglycerides with saturated triglycerides is causing the oxidative stabilization observed for mixed mayonnaise and mixed oil mayonnaise. © 2013 Elsevier Ltd. All rights reserved....

  11. Continuous precipitation of mineral products: influence of mixing conditions on the co-precipitation of cerium-zirconium mixed oxides

    International Nuclear Information System (INIS)

    An automated experimental set-up with rapid mixers is used to study the influence of mixing conditions on the co-precipitation of cerium-zirconium mixed oxides. The intensity of mixing is controlled by the inlet flow rates of the reacting solutions. An engulfment model is used to estimate a mixing time from the measurement of a segregation index by the Villermaux-Dushman reaction system. Three geometries of Hartridge Roughton mixers are compared. Mixing performance is better when a separate mixing chamber upstream of a narrower outlet pipe is present. A better mixing decreases the maximal reducibility temperature of the material and increases the crystal strains of the particles calcined at 1100 C. This is probably due to a better homogenization of the particles content. The important incorporation of nitrates in the particle at the outlet of the mixers shows precipitation occurs while the mixing process is not finished. This experimental result was confirmed by numerical simulation and an estimation of sur-saturations during the mixing process. (author)

  12. Fabrication of ion conductive tin oxide-phosphate amorphous thin films by atomic layer deposition

    International Nuclear Information System (INIS)

    This work reports the atomic layer deposition (ALD) of tin oxide-phosphate films using tetrakis(dimethylamino)tin and trimethyl phosphate as precursors. The growth rates were 1.23–1.84 Å/cycle depending upon the deposition temperature and precursor combination. The ionic conductivity of the ALD tin oxide-phosphate films was evaluated by cross-plane impedance measurements in the temperature range of 50–300 °C under atmospheric air, with the highest conductivity measured as 1.92 × 10−5 S cm−1 at 300 °C. Furthermore, high-resolution x-ray photoelectron spectroscopy exhibited two O1s peaks that were classified as two subpeaks of hydroxyl ions and oxygen ions, revealing that the quantity of hydroxyl ions in the ALD tin oxide-phosphate films influences their ionic conductivity

  13. Effect of Sr on the properties of Ce–Zr–La mixed oxides

    Directory of Open Access Journals (Sweden)

    RICHUAN RAO

    2006-03-01

    Full Text Available Ce–Zr–La–Sr mixed oxides, with different Sr contents, were prepared by the sol–gel method. In a flow-system microreactor, the reduction properties and the oxygen storage capacity (OSC of the Ce–Zr–La–Sr mixed oxides were investigated by a temperature programmed reduction (TPR and a pulse technique. It was shown that the properties of the Ce–Zr–La mixed oxides depend on the Sr content and that the optimum Sr content in the Ce–Zr–La–Sr mixed oxide is 3 mol%. The Ce–Zr–La–Sr mixed oxides doped with 3 mol% Sr (Ce0.52Zr0.4La0.05Sr0.03O1.945 has the largest specific surface area and better reduction properties and oxygen storage capacity in comparison to the other investigated samples. The XRD results of the Ce–Zr–La–Sr mixed oxides showed that their X-ray diffraction patterns are well in agreement with that of fluorite-type CeO2 with Sr ions incorporated into the Ce–Zr–La mixed oxide structures. With increasing calcination temperature, the intensity of the X-ray diffraction peaks increased, but no new peaks were observed. All of these indicate that the synthesized samples had good thermal stability.

  14. Oxidation Prevention Properties of Reduced Graphene Oxide Mixed with 1-Octanethiol-Coated Copper Nanopowder Composites

    Directory of Open Access Journals (Sweden)

    Danee Cho

    2016-01-01

    Full Text Available 1-Octanethiol-coated Cu nanoparticles were mixed with reduced graphene oxide (rGO to fabricate Cu nanoinks with enhanced oxidation prevention. Graphene oxide (GO was synthesized using modified Hummer’s method and rGO was reduced from GO using hydrazine hydrate. Copper nanoinks were fabricated with varying concentrations of rGO (Cu : rGO ratios of 100 : 1, 500 : 1, and 1000 : 1 wt.%. The coating layers on the copper nanoparticles and rGO were observed using transmission electron microscopy and characterized by X-ray photoemission spectroscopy, X-ray diffraction, and Raman spectroscopy. It was observed that surface roughness increased as the concentration of rGO in Cu patterns increased, and an optimized Cu : rGO weight ratio of 1,000 : 1 was established. After sintering, the electrical properties and corrosion resistance of copper patterns both with and without rGO were measured and monitored for 200 days. The copper pattern with rGO (Cu : rGO = 1,000 : 1 was found to maintain its initial resistivity (1.63 × 10−7 Ω·m for 150 days. Corrosion tests were conducted to confirm the oxidation prohibition of rGO. The resistance polarization (Rp of the copper pattern was measured to be 1.5 times higher than that of the copper pattern without rGO. Thus, rGO was shown to prevent oxidation and improve the conductivity of copper patterns.

  15. Development of thin film amorphous silicon oxide/microcrystalline silicon double-junction solar cells and their temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Sriprapha, K.; Piromjit, C.; Limmanee, A.; Sritharathikhun, J. [Institute of Solar Energy Technology Development (SOLARTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Road, Klong 1, Klong Luang, Pathumthani 12120 (Thailand)

    2011-01-15

    We have developed thin film silicon double-junction solar cells by using micromorph structure. Wide bandgap hydrogenated amorphous silicon oxide (a-SiO:H) film was used as an absorber layer of top cell in order to obtain solar cells with high open circuit voltage (V{sub oc}), which are attractive for the use in high temperature environment. All p, i and n layers were deposited on transparent conductive oxide (TCO) coated glass substrate by a 60 MHz-very-high-frequency plasma enhanced chemical vapor deposition (VHF-PECVD) technique. The p-i-n-p-i-n double-junction solar cells were fabricated by varying the CO{sub 2} and H{sub 2} flow rate of i top layer in order to obtain the wide bandgap with good quality material, which deposited near the phase boundary between a-SiO:H and hydrogenated microcrystalline silicon oxide ({mu}c-SiO:H), where the high V{sub oc} can be expected. The typical a-SiO:H/{mu}c-Si:H solar cell showed the highest initial cell efficiency of 10.5%. The temperature coefficient (TC) of solar cells indicated that the values of TC for conversion efficiency ({eta}) of the double-junction solar cells were inversely proportional to the initial V{sub oc}, which corresponds to the bandgap of the top cells. The TC for {eta} of typical a-SiO:H/{mu}c-Si:H was -0.32%/ C, lower than the value of conventional a-Si:H/{mu}c-Si:H solar cell. Both the a-SiO:H/{mu}c-Si:H solar cell and the conventional solar cell showed the same light induced degradation ratio of about 20%. We concluded that the solar cells using wide bandgap a-SiO:H film in the top cells are promising for the use in high temperature regions. (author)

  16. Catalytic performance for methane combustion of supported Mn-Ce mixed oxides

    Institute of Scientific and Technical Information of China (English)

    SHI Limin; CHU Wei; QU Fenfen; HU Jinyan; LI Minmin

    2008-01-01

    A series of supported Mn-Ce mixed oxide catalysts were prepared by the impregnation method and used for the oxidation of methane. The catalysts were characterized by N2 adsorption (BET), X-ray diffraction (XRD), laser Raman spectrum (LRS), and temperature programmed reduction (TPR) techniques. The XRD and LRS results confirmed the high dispersion of active components or formation of solid solution between manganese and cerium oxides in the bulk and on the surface of mixed oxide catalysts. The reducibility was remarka-bly promoted by the stronger synergistic interaction between the two oxides from H2-TPR measurements. As expected, all the experimental mixed oxide catalysts showed excellent activity for methane combustion at low temperature. Especially, for the catalyst with Mn-Ce ratio 3:7, methane conversion reached 92% at a temperature as low as 470 ℃.

  17. Amorphous Zinc Oxide Integrated Wavy Channel Thin Film Transistor Based High Performance Digital Circuits

    KAUST Repository

    Hanna, Amir

    2015-12-04

    High performance thin film transistor (TFT) can be a great driving force for display, sensor/actuator, integrated electronics, and distributed computation for Internet of Everything applications. While semiconducting oxides like zinc oxide (ZnO) present promising opportunity in that regard, still wide area of improvement exists to increase the performance further. Here, we show a wavy channel (WC) architecture for ZnO integrated TFT which increases transistor width without chip area penalty, enabling high performance in material agnostic way. We further demonstrate digital logic NAND circuit using the WC architecture and compare it to the conventional planar architecture. The WC architecture circuits have shown 2× higher peak-to-peak output voltage for the same input voltage. They also have 3× lower high-to-low propagation delay times, respectively, when compared to the planar architecture. The performance enhancement is attributed to both extra device width and enhanced field effect mobility due to higher gate field electrostatics control.

  18. Direct Imaging of Octahedral Distortion in a Complex Molybdenum Vanadium Mixed Oxide

    OpenAIRE

    Lunkenbein, T.; F. Girgsdies; Wernbacher, A.; Noack, J; Auffermann, G.; Yasuhara, A; Klein-Hoffmann, A.; Ueda, W; Eichelbaum, M; Trunschke, A.; Schlögl, R.; Willinger, M.

    2015-01-01

    Complex Mo,V-based mixed oxides that crystallize in the orthorhombic M1-type structure are promising candidates for the selective oxidation of small alkanes. The oxygen sublattice of such a complex oxide has been studied by annular bright field scanning transmission electron microscopy. The recorded micrographs directly display the local distortion in the metal oxygen octahedra. From the degree of distortion we are able to draw conclusions on the distribution of oxidation states in the cation...

  19. Functionalization of Amorphous Chalcogenide and Titanium Oxide Layers by Gold Nanoparticles

    OpenAIRE

    Kökényesi Sándor (1946-) (fizikus); Biri Sándor; Hegedűs Csaba (1953-) (fogszakorvos); Csarnovics István (1986-) (fizikus); Csik Attila

    2014-01-01

    The technology problems of fabricating different, nanometers sized gold particles in the layered composites like light-sensitive chalcogenide glass/gold nanoparticles/transparent substrate or titanium/titanium oxide/gold nanoparticles were investigated in our work. Combination of ion implantation, plasma deposition with annealing processes results physical routes for creation of gold nanoparticles in the mentioned structures, which possess plasmon effects. These functionalized structures are ...

  20. Optical and vibrational spectra analysis of CVD - mixed oxide films: Optimization of the films electrochromic performance

    Energy Technology Data Exchange (ETDEWEB)

    Ivanova, T; Gesheva, K A [Central Laboratory of Solar Energy and New Energy Sources, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria); Abrashev, M [Faculty of Physics, St. Kl. Ohridski University of Sofia, 5 J. Bourchier Blvd., 1164 Sofia (Bulgaria); Sharlandjiev, P; Nazarova, D, E-mail: kagesh@phys.bas.b [Central Laboratory of Optical Storage and Processing of Information, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 101, 1113 Sofia (Bulgaria)

    2010-04-01

    Mixed oxide films based on Mo and W were successfully prepared by atmospheric pressure CVD at the low substrate temperature of 200{sup o}C. High amount of oxygen was used to ensure a high degree of oxidation resulting in more stoichiometric oxide films. The structural transformations under different thermal treatments were studied by Raman spectroscopy and FTIR spectroscopy analysis. The films were characterized electrochemically by cyclic voltammetry using different electrolytes, scan rates, etc. The mixed oxide films exhibited a strong electrochromic (EC) effect.

  1. Optical and vibrational spectra analysis of CVD - mixed oxide films: Optimization of the films electrochromic performance

    International Nuclear Information System (INIS)

    Mixed oxide films based on Mo and W were successfully prepared by atmospheric pressure CVD at the low substrate temperature of 200oC. High amount of oxygen was used to ensure a high degree of oxidation resulting in more stoichiometric oxide films. The structural transformations under different thermal treatments were studied by Raman spectroscopy and FTIR spectroscopy analysis. The films were characterized electrochemically by cyclic voltammetry using different electrolytes, scan rates, etc. The mixed oxide films exhibited a strong electrochromic (EC) effect.

  2. Amorphous silicon oxide layers for surface passivation and contacting of heterostructure solar cells of amorphous and crystalline silicon; Amorphe Siliziumoxidschichten zur Oberflaechenpassivierung und Kontaktierung von Heterostruktur-Solarzellen aus amorphen und kristallinem Silizium

    Energy Technology Data Exchange (ETDEWEB)

    Einsele, Florian

    2010-02-05

    Atomic hydrogen plays a dominant role in the passivation of crystalline silicon surfaces by layers of amorphous silicon. In order to research into this role, this thesis presents the method of hydrogen effusion from thin amorphous films of silicon (a-Si:H) and silicon oxide (a-SiO{sub x}:H). The oxygen concentration of the sub-stoichiometric a-SiO{sub x}:H films ranges up to 10 at.-%. The effusion experiment yields information about the content and thermal stability of hydrogen and about the microstructure of the films. A mathematical description of the diffusion process of atomic hydrogen yields an analytical expression of the effusion rate R{sub E} depending on the linearly increasing temperature in the experiment. Fitting of the calculated effusion rates R{sub E} to measured effusion spectra yields the diffusion coefficient of atomic hydrogen in a-SiO{sub x}:H. With increasing oxygen concentration, the diffusion coefficient of hydrogen in the a-SiO{sub x}:H films decreases. This is attributed to an increasing Si-H bond energy due to back bonded oxygen, resulting in a higher stability of hydrogen in the films. This result is confirmed by an increasing thermal stability of the p-type c-Si passivation with a-SiO{sub x}:H of increasing oxygen concentrations up to 5 at.-%. The passivation reaches very low recombination velocities of S < 10 cm/s at the interface. However, for higher oxygen concentrations up to 10 at.-%, the passivation quality decreases significantly. Here, infrared spectroscopy of Si-H vibrational modes and hydrogen effusion show an increase of hydrogen-rich interconnected voids in the films. This microstructure results in a high amount of molecular hydrogen (H{sub 2}) in the layers, which is not suitable for the saturation of c-Si interface defects. Annealing of the films at temperatures around 400 C leads to a release of H{sub 2} from the voids, as a result of which Si-Si bonds in the material reconstruct. Subsequently, hydrogen migration in the

  3. Leaching of pyrite by acidophilic heterotrophic iron-oxidizing bacteria in pure and mixed cultures

    Energy Technology Data Exchange (ETDEWEB)

    Bacelar-Nicolau, P.; Johnson, D.B. [Univ. of Wales, Bangor (United Kingdom). School of Biological Sciences

    1999-02-01

    Seven strains of heterotrophic iron-oxidizing acidophilic bacteria were examined to determine their abilities to promote oxidative dissolution of pyrite (FeS{sub 2}) when they were grown in pure cultures and in mixed cultures with sulfur-oxidizing Thiobacillus spp. Only one of the isolates (strain T-24) oxidized pyrite when it was grown in pyrite-basal salts medium. However, when pyrite-containing cultures were supplemented with 0.02% (wt/vol) yeast extract, most of the isolates oxidized pyrite, and one (strain T-24) promoted rates of mineral dissolution similar to the rates observed with the iron-oxidizing autotroph Thiobacillus ferroxidans. Pyrite oxidation by another isolate (strain T-21) occurred in cultures containing between 0.005 and 0.05% (wt/vol) yeast extract but was completely inhibited in cultures containing 0.5% yeast extract. Ferrous iron was also needed for mineral dissolution by the iron-oxidizing heterotrophs, indicating that these organisms oxidize pyrite via the indirect mechanism. Mixed cultures of three isolates (strains T-21, T-232, and T-24) and the sulfur-oxidizing autotroph Thiobacillus thiooxidans promoted pyrite dissolution; since neither strains T-21 and T-23 nor T. thiooxidans could oxidize this mineral in yeast extract-free media, this was a novel example of bacterial synergism. Mixed cultures of strains T-21 and T-23 and the sulfur-oxidizing mixotroph Thiobacillus acidophilus also oxidized pyrite but to a lesser extent than did mixed cultures containing T. thiooxidans. Pyrite leaching by strain T -23 grown in an organic compound-rich medium and incubated either shaken or unshaken was also assessed. The potential environmental significance of iron-oxidizing heterotrophs in accelerating pyrite oxidation is discussed.

  4. Nanoparticles of TiAlZr mixed oxides as supports of hydrodesulfurization catalysts: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Kraleva, E., E-mail: ekraleva@gmail.com [Institute of Biodiversity and Ecosystems Research, Bulgarian Academy of Sciences, Sofia, Gagarin st.2 (Bulgaria); Spojakina, A. [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Saladino, M.L. [Dipartimento di Chimica ' S. Cannizzaro' , Universita di Palermo and INSTM-Udr Palermo, Parco d' Orleans II Viale delle Scienze pad 17, I-90128 Palermo,Italy (Italy); Caponetti, E. [Dipartimento di Chimica ' S. Cannizzaro' , Universita di Palermo and INSTM-Udr Palermo, Parco d' Orleans II Viale delle Scienze pad 17, I-90128 Palermo,Italy (Italy); Centro Grandi Apparecchiature - UniNetLab, Universita di Palermo, Via F. Marini 14, I-90128 Palermo (Italy); Nasillo, G. [Centro Grandi Apparecchiature - UniNetLab, Universita di Palermo, Via F. Marini 14, I-90128 Palermo (Italy); Jiratova, K. [Institute of Chemical Process Fundamentals, 16502 Prague 6 (Czech Republic)

    2012-02-05

    Highlights: Black-Right-Pointing-Pointer Preparation of ternary mixed oxide by sol-gel method. Black-Right-Pointing-Pointer Catalytic properties of the three-mixed oxides. Black-Right-Pointing-Pointer Heteropolyacid H{sub 3}PMo{sub 12}O{sub 40} and its cobalt salt Co{sub 1.5}PMo{sub 12}O{sub 40} that of active components in catalytic systems for thiophene hydrodesulfurization (HDS). - Abstract: TiAlZr mixed oxides, synthesized using sol-gel method, were characterized and used as supports of hydrodesulfurization catalysts (12 wt% Mo) prepared by impregnation either with molybdenum heteropolyacid H{sub 3}PMo{sub 12}O{sub 40} or its cobalt salt Co{sub 1.5}PMo{sub 12}O{sub 40}. Structure, morphology and textural properties of oxides and catalysts were characterized using X-ray powder diffraction (XRD), Raman spectroscopy, Nitrogen adsorption porosimetry, TEM-EDS, temperature-programmed desorption (TPD) and temperature-programmed reduction (TPR) techniques. Activity of the catalytic systems was tested in thiophene hydrodesulfurization (HDS). No formation of a new oxide phase was revealed in the synthesized mixed materials. However the effect of separated oxides on the structure of ternary oxides was observed. Maximum in HDS activity of Mo containing samples was determined by optimum content of alumina in the mixed oxides. Incorporation of cobalt into the heteropolyacid increased the HDS activity about two times and masked the effect of the support composition.

  5. Nanoparticles of TiAlZr mixed oxides as supports of hydrodesulfurization catalysts: Synthesis and characterization

    International Nuclear Information System (INIS)

    Highlights: ► Preparation of ternary mixed oxide by sol–gel method. ► Catalytic properties of the three-mixed oxides. ► Heteropolyacid H3PMo12O40 and its cobalt salt Co1.5PMo12O40 that of active components in catalytic systems for thiophene hydrodesulfurization (HDS). - Abstract: TiAlZr mixed oxides, synthesized using sol–gel method, were characterized and used as supports of hydrodesulfurization catalysts (12 wt% Mo) prepared by impregnation either with molybdenum heteropolyacid H3PMo12O40 or its cobalt salt Co1.5PMo12O40. Structure, morphology and textural properties of oxides and catalysts were characterized using X-ray powder diffraction (XRD), Raman spectroscopy, Nitrogen adsorption porosimetry, TEM-EDS, temperature-programmed desorption (TPD) and temperature-programmed reduction (TPR) techniques. Activity of the catalytic systems was tested in thiophene hydrodesulfurization (HDS). No formation of a new oxide phase was revealed in the synthesized mixed materials. However the effect of separated oxides on the structure of ternary oxides was observed. Maximum in HDS activity of Mo containing samples was determined by optimum content of alumina in the mixed oxides. Incorporation of cobalt into the heteropolyacid increased the HDS activity about two times and masked the effect of the support composition.

  6. Designed synthesis of tunable amorphous carbon nanotubes (a-CNTs) by a novel route and their oxidation resistance properties

    Indian Academy of Sciences (India)

    Longlong Xu; Yifu Zhang; Xiongzhi Zhang; Yu Huang; Xiaoyu Tan; Chi Huang; Xiao Mei; Fei Niu; Changgong Meng; Gongzhen Cheng

    2014-10-01

    Tunable amorphous carbon nanotubes (a-CNTs) were successfully synthesized using V3O7.H2O and glucose solution as the starting materials by a novel route for the first time. The as-obtained samples were separately characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), energy-dispersive spectrometer (EDS), elemental analysis (EA), Fourier transform infrared spectroscopy (FT–IR) and Raman spectrum. The results showed that the as-obtained a-CNTs had uniform diameters with outer diameter ranging from 140 to 250 nm and inner diameter about 28 nm on an average, and their length was up to several micrometres. No VO residues remaining in a-CNTs showed the as-obtained a-CNTs with high purity. The as-prepared a-CNTs were a kind of hydrogenated a-CNTs containing both the 3- and 2-type carbons. Furthermore, the thermal stability of the as-obtained a-CNTs in the air atmosphere were investigated by thermo-gravimetric/differential thermal analyser (TG-DTA), revealing that the as-obtained a-CNTs had good thermal stability and oxidation resistance below 300 °C in air.

  7. Semiconductor to metallic transition in bulk accumulated amorphous indium-gallium-zinc-oxide dual gate thin-film transistor

    International Nuclear Information System (INIS)

    We investigated the effects of top gate voltage (VTG) and temperature (in the range of 25 to 70 oC) on dual-gate (DG) back-channel-etched (BCE) amorphous-indium-gallium-zinc-oxide (a-IGZO) thin film transistors (TFTs) characteristics. The increment of VTG from -20V to +20V, decreases the threshold voltage (VTH) from 19.6V to 3.8V and increases the electron density to 8.8 x 1018cm−3. Temperature dependent field-effect mobility in saturation regime, extracted from bottom gate sweep, show a critical dependency on VTG. At VTG of 20V, the mobility decreases from 19.1 to 15.4 cm2/V ⋅ s with increasing temperature, showing a metallic conduction. On the other hand, at VTG of - 20V, the mobility increases from 6.4 to 7.5cm2/V ⋅ s with increasing temperature. Since the top gate bias controls the position of Fermi level, the temperature dependent mobility shows metallic conduction when the Fermi level is above the conduction band edge, by applying high positive bias to the top gate

  8. Channel length dependence of negative-bias-illumination-stress in amorphous-indium-gallium-zinc-oxide thin-film transistors

    International Nuclear Information System (INIS)

    We have investigated the dependence of Negative-Bias-illumination-Stress (NBIS) upon channel length, in amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). The negative shift of the transfer characteristic associated with NBIS decreases for increasing channel length and is practically suppressed in devices with L = 100-μm. The effect is consistent with creation of donor defects, mainly in the channel regions adjacent to source and drain contacts. Excellent agreement with experiment has been obtained by an analytical treatment, approximating the distribution of donors in the active layer by a double exponential with characteristic length LD ∼ Ln ∼ 10-μm, the latter being the electron diffusion length. The model also shows that a device with a non-uniform doping distribution along the active layer is in all equivalent, at low drain voltages, to a device with the same doping averaged over the active layer length. These results highlight a new aspect of the NBIS mechanism, that is, the dependence of the effect upon the relative magnitude of photogenerated holes and electrons, which is controlled by the device potential/band profile. They may also provide the basis for device design solutions to minimize NBIS

  9. Contact resistance asymmetry of amorphous indium-gallium-zinc-oxide thin-film transistors by scanning Kelvin probe microscopy

    Science.gov (United States)

    Chen-Fei, Wu; Yun-Feng, Chen; Hai, Lu; Xiao-Ming, Huang; Fang-Fang, Ren; Dun-Jun, Chen; Rong, Zhang; You-Dou, Zheng

    2016-05-01

    In this work, a method based on scanning Kelvin probe microscopy is proposed to separately extract source/drain (S/D) series resistance in operating amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors. The asymmetry behavior of S/D contact resistance is deduced and the underlying physics is discussed. The present results suggest that the asymmetry of S/D contact resistance is caused by the difference in bias conditions of the Schottky-like junction at the contact interface induced by the parasitic reaction between contact metal and a-IGZO. The overall contact resistance should be determined by both the bulk channel resistance of the contact region and the interface properties of the metal-semiconductor junction. Project supported by the Key Industrial R&D Program of Jiangsu Province, China (Grant No. BE2015155), the Priority Academic Program Development of Higher Education Institutions of Jiangsu Province, China, and the Fundamental Research Funds for the Central Universities, China (Grant No. 021014380033).

  10. Semiconductor to metallic transition in bulk accumulated amorphous indium-gallium-zinc-oxide dual gate thin-film transistor

    Directory of Open Access Journals (Sweden)

    Minkyu Chun

    2015-05-01

    Full Text Available We investigated the effects of top gate voltage (VTG and temperature (in the range of 25 to 70 oC on dual-gate (DG back-channel-etched (BCE amorphous-indium-gallium-zinc-oxide (a-IGZO thin film transistors (TFTs characteristics. The increment of VTG from -20V to +20V, decreases the threshold voltage (VTH from 19.6V to 3.8V and increases the electron density to 8.8 x 1018cm−3. Temperature dependent field-effect mobility in saturation regime, extracted from bottom gate sweep, show a critical dependency on VTG. At VTG of 20V, the mobility decreases from 19.1 to 15.4 cm2/V ⋅ s with increasing temperature, showing a metallic conduction. On the other hand, at VTG of - 20V, the mobility increases from 6.4 to 7.5cm2/V ⋅ s with increasing temperature. Since the top gate bias controls the position of Fermi level, the temperature dependent mobility shows metallic conduction when the Fermi level is above the conduction band edge, by applying high positive bias to the top gate.

  11. Channel length dependence of negative-bias-illumination-stress in amorphous-indium-gallium-zinc-oxide thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Um, Jae Gwang; Mativenga, Mallory; Jang, Jin, E-mail: jjang@khu.ac.kr [Advanced Display Research Center, Department of Information Display, Kyung Hee University, Dongdaemun-gu, Seoul 130-701 (Korea, Republic of); Migliorato, Piero [Advanced Display Research Center, Department of Information Display, Kyung Hee University, Dongdaemun-gu, Seoul 130-701 (Korea, Republic of); Electrical Engineering Division, Department of Engineering, Cambridge University, Cambridge CB3 0FA (United Kingdom)

    2015-06-21

    We have investigated the dependence of Negative-Bias-illumination-Stress (NBIS) upon channel length, in amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). The negative shift of the transfer characteristic associated with NBIS decreases for increasing channel length and is practically suppressed in devices with L = 100-μm. The effect is consistent with creation of donor defects, mainly in the channel regions adjacent to source and drain contacts. Excellent agreement with experiment has been obtained by an analytical treatment, approximating the distribution of donors in the active layer by a double exponential with characteristic length L{sub D} ∼ L{sub n} ∼ 10-μm, the latter being the electron diffusion length. The model also shows that a device with a non-uniform doping distribution along the active layer is in all equivalent, at low drain voltages, to a device with the same doping averaged over the active layer length. These results highlight a new aspect of the NBIS mechanism, that is, the dependence of the effect upon the relative magnitude of photogenerated holes and electrons, which is controlled by the device potential/band profile. They may also provide the basis for device design solutions to minimize NBIS.

  12. Semiconductor to metallic transition in bulk accumulated amorphous indium-gallium-zinc-oxide dual gate thin-film transistor

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Minkyu; Chowdhury, Md Delwar Hossain; Jang, Jin, E-mail: jjang@khu.ac.kr [Advanced Display Research Center and Department of Information Display, Kyung Hee University, Seoul 130-701 (Korea, Republic of)

    2015-05-15

    We investigated the effects of top gate voltage (V{sub TG}) and temperature (in the range of 25 to 70 {sup o}C) on dual-gate (DG) back-channel-etched (BCE) amorphous-indium-gallium-zinc-oxide (a-IGZO) thin film transistors (TFTs) characteristics. The increment of V{sub TG} from -20V to +20V, decreases the threshold voltage (V{sub TH}) from 19.6V to 3.8V and increases the electron density to 8.8 x 10{sup 18}cm{sup −3}. Temperature dependent field-effect mobility in saturation regime, extracted from bottom gate sweep, show a critical dependency on V{sub TG}. At V{sub TG} of 20V, the mobility decreases from 19.1 to 15.4 cm{sup 2}/V ⋅ s with increasing temperature, showing a metallic conduction. On the other hand, at V{sub TG} of - 20V, the mobility increases from 6.4 to 7.5cm{sup 2}/V ⋅ s with increasing temperature. Since the top gate bias controls the position of Fermi level, the temperature dependent mobility shows metallic conduction when the Fermi level is above the conduction band edge, by applying high positive bias to the top gate.

  13. Effect of Ta addition of co-sputtered amorphous tantalum indium zinc oxide thin film transistors with bias stability.

    Science.gov (United States)

    Son, Dae-Ho; Kim, Dae-Hwan; Park, Si-Nae; Sung, Shi-Joon; Kang, Jin-Kyu

    2014-11-01

    In this work, we have fabricated thin film transistors (TFTs) using amorphous tantalum indium zinc oxide (a-TaInZnO) channels by the co-sputtering process. The effects of incorporating tantalum on the InZnO material were investigated using Hall-effect measurement results, and electrical characteristics. We also found that the carrier densities of thin films and the transistor on-off currents were greatly influenced by the composition of tantalum addition. Ta ions have strong affinity to oxygen and so suppress the formation of free electron carriers inthin films; they play an important role in enhancing the electrical characteristic due to their high oxygen bonding ability. The electrical characteristics of the optimized TFTs shows a field effect mobility of 3.67 cm2 V(-1) s(-1), a threshold voltage of 1.28 V, an on/off ratio of 1.1 x 10(8), and a subthreshold swing of 480 mV/dec. Under gate bias stress conditions, the TaInZnO TFTs showed lower shift in threshold voltage shifts. PMID:25958492

  14. Contact resistance asymmetry of amorphous indium–gallium–zinc–oxide thin-film transistors by scanning Kelvin probe microscopy

    Science.gov (United States)

    Chen-Fei, Wu; Yun-Feng, Chen; Hai, Lu; Xiao-Ming, Huang; Fang-Fang, Ren; Dun-Jun, Chen; Rong, Zhang; You-Dou, Zheng

    2016-05-01

    In this work, a method based on scanning Kelvin probe microscopy is proposed to separately extract source/drain (S/D) series resistance in operating amorphous indium–gallium–zinc–oxide (a-IGZO) thin-film transistors. The asymmetry behavior of S/D contact resistance is deduced and the underlying physics is discussed. The present results suggest that the asymmetry of S/D contact resistance is caused by the difference in bias conditions of the Schottky-like junction at the contact interface induced by the parasitic reaction between contact metal and a-IGZO. The overall contact resistance should be determined by both the bulk channel resistance of the contact region and the interface properties of the metal-semiconductor junction. Project supported by the Key Industrial R&D Program of Jiangsu Province, China (Grant No. BE2015155), the Priority Academic Program Development of Higher Education Institutions of Jiangsu Province, China, and the Fundamental Research Funds for the Central Universities, China (Grant No. 021014380033).

  15. Single crystal particles of a mesoporous mixed transition metal oxide with a wormhole structure.

    Science.gov (United States)

    Lee, B; Lu, D; Kondo, J N; Domen, K

    2001-10-21

    A new type of mesoporous mixed transition metal oxide of Nb and Ta (NbTa-TIT-1) has been prepared through a two-step calcination, which consists of single crystal particles with wormhole mesoporous structure. PMID:12240191

  16. Study on Catalysts with Rhodium Loading on Different Cerium-Zirconium Mixed Oxides

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The catalysts with Rh loading on different cerium-zirconium mixed oxides were characterized by BET, H2-TPR and OSC. The effects of different cerium-zirconium mixed oxides on catalytic performance and thermal stability of Rh loaded catalyst were studied. The results show that: (1) Rh can enhance cerium-zirconium mixed oxides OSC and catalytic reaction rates; (2) cerium-zirconium mixed oxides with high Ce contents and low Zr contents are more favorable to the stability of catalysts. Moreover, the contents of CeO2 have important effect on catalysts characteristics, and the addition of some rare earth components, such as La, Pr and Nd also have some influences.

  17. Preparation of mixed oxides (Th,U)O2: an evaluation of different techniques

    International Nuclear Information System (INIS)

    An evaluation of different ways of obtaining (Th-U)O2 mixed oxides is described. Coprecipitation, mechanical mixing of uranium and thorium powders, and the sol-gel technique were studied in order to get a large spectrum of knowledge of the process performance. The use of ultrasonic waves for the homogenization of the hydroxide mixture and microwave heating for powder drying was also investigated. Sol-gel showed the best results regarding the specific area for obtained samples. Oxide drying by microwave is an effective method to get mixed oxides for fuel fabrication. Neither coprecipitation nor mechanical mixing of the thorium and uranium oxide powders is suitable for the purpose. The obtained data are less than 70% than those achieved when sol-gel process is performed. Electronic microscopy, X-ray fluorescence and diffraction, thermogravimetry, specific gravidity and specific area determination (BET) used for sample characterization were convenient and accomplished good results. (author)

  18. Different Abilities of Eight Mixed Cultures of Methane-oxidizing Bacteria to Degrade TCE

    DEFF Research Database (Denmark)

    Broholm, Kim; Christensen, Thomas Højlund; Jensen, Bjørn K.

    1993-01-01

    The ability of eight mixed cultures of methane-oxidizing bacteria to degrade trichloroethylene (TCE) was examined in laboratory batch experiments. This is one of the first reported works studying TCE degradation by mixed cultures of methane-oxidizing bacteria at 10°C, a common temperature for soils...... and groundwaters. Only three of the eight mixed cultures were able to degrade TCE, or to degrade TCE fast enough to result in a significant removal of TCE within the experimental time, when the cultures used methane as growth substrate. The same three mixed cultures were able to degrade TCE when they oxidized...... methanol, but only for a limited time period of about 5 days. Several explanations for the discontinued degradation of TCE are given. An experiment carried out to re-activate the methane-oxidizing bacteria after 8 days of growth on methanol by adding methane did not immediately result in degradation...

  19. Reduction of tail state on boron doped hydrogenated amorphous silicon oxide films prepared at high hydrogen dilution.

    Science.gov (United States)

    Park, Jinjoo; Iftiquar, S M; Lee, Sunwha; Park, Hyeongsik; Shin, Chonghoon; Jung, Junhee; Lee, Youn-Jung; Balaji, Nagarajan; Yi, Junsin

    2013-12-01

    In this report, we have investigated on the defect state of diborane (B2H6) doped wide bandgap hydrogenated amorphous silicon oxide (p-type a-SiO:H) films prepared using silane (SiH4), hydrogen (H2) and nitrous oxide (N2O) in a radio frequency (RF) plasma enhanced chemical vapor deposition (PECVD) system with different hydrogen dilutions. The films prepared with higher hydrogen dilution show lower Urbach energy (Eu), lower microstructure (R*), lower short and medium range disorder (omegaTO, Gamma(TO), I(TA)/I(TO), I(LA)/I(TO)), higher dark conductivity (sigma d) and higher refractive index (n) with high optical gap (Eg). Eu decreases from 248 meV to 153 meV, and R* decreases from 0.46 to 0.26, Raman peak omegaTO-TO mode position shifts from 480.24 to 483.28, GammaTO-full width half maximum of omegaTO decreases from 78.16 to 63.87, I(TA)/I(TO)-the ratio of integrated area of TA and TO mode decreases from 0.624 to 0.474, I(LA)/I(TO)-the ratio of integrated area of LA and TO mode deceases from 0.272 to 0.151, sigma d increases from 4.6 x 10(-7) S/cm to 1.1 x 10(-6) S/cm, n increases from 3.70 to 3.86. Reduced Nd, Eu and R* at wide Eg indicates that the films are more useful for solar cell window layer. Applying this layer to a single junction solar cell shows open circuit voltage (Voc) = 0.80 V, short circuit current density (Jsc) = 16.3 mA/cm2, fill factor (FF) = 72%, efficiency (eta) = 9.4%. PMID:24266147

  20. Analysis of amorphous indium-gallium-zinc-oxide thin-film transistor contact metal using Pilling-Bedworth theory and a variable capacitance diode model

    OpenAIRE

    Kiani, Ahmed; Hasko1, David G; William I. Milne; Flewitt, Andrew J.

    2013-01-01

    It is widely reported that threshold voltage and on-state current of amorphous indiumgallium- zinc-oxide bottom-gate thin-film transistors is strongly influenced by the choice of source/drain contact metal. Electrical characterisation of thin-film transistors indicates that the electrical properties depend on the type and thickness of the metal(s) used. Electron transport mechanisms and possibilities for control of the defect state density are discussed. Pilling-Bedworth theory...

  1. Study on Mg/Fe Mixed Oxides Derived from Hydrotalcite as De-SOx Catalyst

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A novel class of desulfurization agent derived from hydrotalcite has been developed and its activity for Sox uptake have been investigated. The results showed that the Mg/Fe mixed oxide having high Sox uptake ability at a broad reaction temperature (e.g. 673K ~ 973K). The Mg/Fe ratio of the mixed oxide strongly affect the desulfurization role of the material and it can be used repeatly without much loss of Sox uptake ability.

  2. Study on Mg/Fe Mixed Oxides Derived from Hydrotalite as De—SOx Catalyst

    Institute of Scientific and Technical Information of China (English)

    GuangLanZHUO; YinFeiCHEN; 等

    2002-01-01

    A novel class of desulfurization agent derived from hydrotalcite has been developed and its activity for SOx uptake have been investigated. The results showed that the Mg/Fe mixed oxide having high SOx uptake ability at a broad reaction temperature (e.g.673K-973K). The Mg/Fe ratio of the mixed oxide strongly affect the desulfurization role of the material and it can be used repeatly without much loss of SOx uptake ability.

  3. Feasibility Study of 1/3 Thorium-Plutonium Mixed Oxide Core

    OpenAIRE

    2014-01-01

    Thorium-plutonium mixed oxide (Th-MOX) fuel has become one of the most promising solutions to reduce a large and increasing plutonium stockpile. Compared with traditional uranium-plutonium mixed oxide (U-MOX) fuels, Th-MOX fuel has higher consumption rate of plutonium in LWRs. Besides, thorium based fuels have improved thermomechanical material properties compared with traditional U-MOX fuels. Previous studies on a full Th-MOX core have shown reduced efficiency in reactivity control mechanism...

  4. Mixed-chelate therapy of intratracheally deposited cadmium oxide

    International Nuclear Information System (INIS)

    Mixed-chelate treatment with EDTA and salicylic acid was no more effective in accelerating the removal of intratracheally instilled 109CdO, or in protecting against CdO-induced mortality, than was EDTA given alone

  5. Molten carbonate fuel cell cathode with mixed oxide coating

    Science.gov (United States)

    Hilmi, Abdelkader; Yuh, Chao-Yi

    2013-05-07

    A molten carbonate fuel cell cathode having a cathode body and a coating of a mixed oxygen ion conductor materials. The mixed oxygen ion conductor materials are formed from ceria or doped ceria, such as gadolinium doped ceria or yttrium doped ceria. The coating is deposited on the cathode body using a sol-gel process, which utilizes as precursors organometallic compounds, organic and inorganic salts, hydroxides or alkoxides and which uses as the solvent water, organic solvent or a mixture of same.

  6. Characterization and simulation on antireflective coating of amorphous silicon oxide thin films with gradient refractive index

    Science.gov (United States)

    Huang, Lu; Jin, Qi; Qu, Xingling; Jin, Jing; Jiang, Chaochao; Yang, Weiguang; Wang, Linjun; Shi, Weimin

    2016-08-01

    The optical reflective properties of silicon oxide (SixOy) thin films with gradient refractive index are studied both theoretically and experimentally. The thin films are widely used in photovoltaic as antireflective coatings (ARCs). An effective finite difference time domain (FDTD) model is built to find the optimized reflection spectra corresponding to structure of SixOy ARCs with gradient refractive index. Based on the simulation analysis, it shows the variation of reflection spectra with gradient refractive index distribution. The gradient refractive index of SixOy ARCs can be obtained in adjustment of SiH4 to N2O ratio by plasma-enhanced chemical vapor deposition (PECVD) system. The optimized reflection spectra measured by UV-visible spectroscopy confirms to agree well with that simulated by FDTD method.

  7. Method for the manufacture of nitric acid soluble mixed oxide fuel pellets

    International Nuclear Information System (INIS)

    For the manufacture of nitric acid-soluble mixed oxide fuel pellets with adjustable proportions, the starting powder is ground down to a primary grain size of < 2 μm together with a halogen-free grinding aid and subsequently mixed. The change is then granulated in a rotating chamber, pressed into pellet form and sintered. (orig.)

  8. E-beam and UV induced fabrication of CeO2, Eu2O3 and their mixed oxides with UO2

    Science.gov (United States)

    Pavelková, Tereza; Vaněček, Vojtěch; Jakubec, Ivo; Čuba, Václav

    2016-07-01

    CeO2, Eu2O3 and mixed oxides of CeO2-UO2, Eu2O3-UO2 were fabricated. The preparative method was based on the irradiation of aqueous solutions containing cerium/europium (and uranyl) nitrates and ammonium formate. In the course of irradiation, the solid phase (precursor) was precipitated. The composition of irradiated solutions significantly affected the properties of precursor formed in the course of the irradiation. However, subsequent heat treatment of (amorphous) precursors at temperatures ≤650 °C invariably resulted in the formation of powder oxides with well-developed nanocrystals with linear crystallite size 13-27 nm and specific surface area 10-46 m2 g-1. The applicability of both ionizing (e-beam) and non-ionizing (UV) radiation was studied.

  9. Impurity analysis in dirty rejected oxide generated during mixed oxide fuel fabrication

    International Nuclear Information System (INIS)

    Uranium and plutonium mixed oxide (MOX) fuel is being fabricated for Prototype Fast Breeder Reactor (PFBR) at Advanced Fuel Fabrication Facility (AFFF), Tarapur having two compositions viz. (U,21% Pu)O2 and (U,28% Pu)O2. Inherently, during various stages of fabrication process, Pu bearing scraps gets generated. Broadly these scraps are categorized as clean rejected oxide (CRO) and dirty rejected oxide (DRO) depending upon the chemical impurity content. The valuable fissile material 'Pu' needs to be recovered from scrap and reuse for fuel fabrication. A microwave based wet direct denitration process for recycling and re-use of CRO has been developed and adapted at AFFF. Nearly 2% of processed fuel material is generated as DRO. The concerns associated with long term storage of the scraps are mainly fissile content degradation and men-rem besides economic. Since the content of Pu in the scraps is high and significant quantities are piled-up during a campaign. Essentially processes are required to be developed for in-house recovery and recycling of these scraps. Thus it is important to analyse the impurities in the scraps with regard to chemical nature, total content, source and deviation from the acceptable levels. In the present paper, estimation of impurities in DRO generated during various operations was carried out. The specified metallic (Al, Ag, B, Be, Cd, Ca, Mg, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sn, Si, W, Zn etc.) and non-metallic (C, H, Cl and F) impurities were determined in 25 samples. Metallic impurities were determined by a glove box adapted ICP-OES. C was determined by combustion following IR absorptive measurement. IGF followed by TCD measurement was employed for H determination. Cl and F were measured by respective ISEs after pyrohydrolytic extraction

  10. Route of electrochemical oxidation of the antibiotic sulfamethoxazole on a mixed oxide anode.

    Science.gov (United States)

    Hussain, Sajjad; Gul, Saima; Steter, Juliana R; Miwa, Douglas W; Motheo, Artur J

    2015-10-01

    The appearance of pharmaceutical compounds and their bioactive transformation products in aquatic environments is becoming an issue of increasing concern. In this study, the electrochemical oxidation of the widely used antibiotic sulfamethoxazole (SMX) was investigated using a commercial mixed oxide anode (Ti/Ru0.3Ti0.7O2) and a single compartment filter press-type flow reactor. The kinetics of SMX degradation was determined as a function of electrolyte composition, applied current density, and initial pH. Almost complete (98 %) degradation of SMX could be achieved within 30 min of electrolysis in 0.1 mol L(-1) NaCl solution at pH 3 with applied current densities ≥20 mA cm(-2). Nine major intermediates of the reaction were identified by LC-ESI-Q-TOF-MS (e.g., C6H9NO2S (m/z = 179), C6H4NOCl (m/z = 141), and C6H6O2 (m/z = 110)). The degradation followed various routes involving cleavage of the oxazole and benzene rings by hydroxyl and/or chlorine radicals, processes that could occur before or after rupture of the N-S bond, followed by oxidation of the remaining moieties. Analysis of the total organic carbon content revealed that the antibiotic was partially mineralized under the conditions employed and some inorganic ions, including NO3 (-) and SO4 (2-), could be identified. The results presented herein demonstrate the efficacy of the electrochemical process using a Ti/Ru0.3Ti0.7O2 anode for the remediation of wastewater containing the antibiotic SMX. PMID:26002364

  11. MC3T3-E1 cell response of amorphous phase/TiO{sub 2} nanocrystal composite coating prepared by microarc oxidation on titanium

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Rui [Department of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wei, Daqing, E-mail: daqingwei@hit.edu.cn [Department of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Yang, Haoyue; Feng, Wei [Department of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Cheng, Su [Department of Mechanical Engineering, School of Architecture and Civil Engineering, Harbin University of Science and Technology, Harbin 150001 (China); Li, Baoqiang; Wang, Yaming; Jia, Dechang; Zhou, Yu [Department of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2014-06-01

    Bioactive amorphous phase/TiO{sub 2} nanocrystal (APTN) composite coatings were fabricated by microarc oxidation (MAO) on Ti. The APTN coatings are composed of much amorphous phase with Si, Na, Ca, Ti and O elements and a few TiO{sub 2} nanocrystals. With increasing applied voltage, the micropore density of the APTN coating decreases and the micropore size of the APTN coating increases. The results indicate that less MC3T3-E1 cells attach on the APTN coatings as compared to Ti. However, the APTN coatings greatly enhance the cell proliferation ability and the activity of alkaline phosphatase. The amorphous phase and the concentrations of the released Ca and Si from the APTN coatings during cell culture have significant effects on the cell response. - Highlights: • Amorphous phase/TiO2 nanocrystal (APTN) composite coatings were fabricated. • The MC3T3-E1 cell response of the APTN coatings was evaluated. • The APTN coatings greatly enhanced the cell proliferation ability.

  12. Ferroelectric switching of poly(vinylidene difluoride-trifluoroethylene) in metal-ferroelectric-semiconductor non-volatile memories with an amorphous oxide semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Gelinck, G. H., E-mail: Gerwin.Gelinck@tno.nl [Holst Centre/TNO, High Tech Campus 31, 5656 AE Eindhoven (Netherlands); Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Breemen, A. J. J. M. van; Cobb, B. [Holst Centre/TNO, High Tech Campus 31, 5656 AE Eindhoven (Netherlands)

    2015-03-02

    Ferroelectric polarization switching of poly(vinylidene difluoride-trifluoroethylene) is investigated in different thin-film device structures, ranging from simple capacitors to dual-gate thin-film transistors (TFT). Indium gallium zinc oxide, a high mobility amorphous oxide material, is used as semiconductor. We find that the ferroelectric can be polarized in both directions in the metal-ferroelectric-semiconductor (MFS) structure and in the dual-gate TFT under certain biasing conditions, but not in the single-gate thin-film transistors. These results disprove the common belief that MFS structures serve as a good model system for ferroelectric polarization switching in thin-film transistors.

  13. Degradation of organophosphorus pesticide parathion methyl on nanostructured titania-iron mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Henych, Jiří, E-mail: henych@iic.cas.cz [Department of Material Chemistry, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Řež (Czech Republic); Štengl, Václav; Slušná, Michaela; Matys Grygar, Tomáš [Department of Material Chemistry, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Řež (Czech Republic); Janoš, Pavel; Kuráň, Pavel; Štastný, Martin [Faculty of the Environment, J.E. Purkyně University, Králova Výšina 7, 400 96 Ústí nad Labem (Czech Republic)

    2015-07-30

    Highlights: • Ti–Fe mixed oxides were synthesized via low-temperature one-pot method. • Mixed oxides were used for degradation of parathion methyl. • Pure reference oxide samples showed no degradation ability. • Mixed oxides reached 70% degree of conversion of parathion methyl. - Abstract: Titania-iron mixed oxides with various Ti:Fe ratio were prepared by homogeneous hydrolysis of aqueous solutions of titanium(IV) oxysulphate and iron(III) sulphate with urea as a precipitating agent. The synthesized samples were characterized by X-ray diffraction, Raman and infrared spectroscopy, scanning and transmission electron microscopy, XRF analysis, specific surface area (BET) and porosity determination (BJH). These oxides were used for degradation of organophosporus pesticide parathion methyl. The highest degradation efficiency approaching <70% was found for the samples with Ti:Fe ratio 0.25:1 and 1:0.25. Contrary, parathion methyl was not degraded on the surfaces of pure oxides. In general, the highest degradation rate exhibited samples consisted of the iron or titanium oxide containing a moderate amount of the admixture. However, distinct correlations between the degradation rate and the sorbent composition were not identified.

  14. Preliminary comparison of three processes of AlN oxidation: dry, wet and mixed ones

    OpenAIRE

    Korbutowicz R.; Zakrzewski A.

    2016-01-01

    Three methods of AlN layers oxidation: dry, wet and mixed (wet with oxygen) were compared. Some physical parameters of oxidized thin films of aluminum nitride (AlN) layers grown on silicon Si(1 1 1) were investigated by means Energy-Dispersive X-ray Spectroscopy (EDS) and Spectroscopic Ellipsometry (SE). Three series of the thermal oxidations processes were carried out at 1012 °C in pure nitrogen as carrying gas and various gas ambients: (a) dry oxidation with oxygen, (b) wet oxidation with w...

  15. Mixed conductivity in terbia-stabilized bismuth oxide

    NARCIS (Netherlands)

    Vinke, I.C.; Boukamp, B.A.; Vries, de K.J.; Burggraaf, A.J.

    1992-01-01

    The mixed conducting solid solution 0.75Bi2O3−0.25Tb4O7 (BT40) was studied by impedance techniques using ionically blocking electrodes. These measurements confirmed the p-type electronic conductivity suggested in literature. In air at temperatures between 600 and 900 K the ionic transference number

  16. Study of an Amorphous Silicon Oxide Buffer Layer for p-Type Microcrystalline Silicon Oxide/n-Type Crystalline Silicon Heterojunction Solar Cells and Their Temperature Dependence

    Directory of Open Access Journals (Sweden)

    Taweewat Krajangsang

    2014-01-01

    Full Text Available Intrinsic hydrogenated amorphous silicon oxide (i-a-SiO:H films were used as front and rear buffer layers in crystalline silicon heterojunction (c-Si-HJ solar cells. The surface passivity and effective lifetime of these i-a-SiO:H films on an n-type silicon wafer were improved by increasing the CO2/SiH4 ratios in the films. Using i-a-SiO:H as the front and rear buffer layers in c-Si-HJ solar cells was investigated. The front i-a-SiO:H buffer layer thickness and the CO2/SiH4 ratio influenced the open-circuit voltage (Voc, fill factor (FF, and temperature coefficient (TC of the c-Si-HJ solar cells. The highest total area efficiency obtained was 18.5% (Voc=700 mV, Jsc=33.5 mA/cm2, and FF=0.79. The TC normalized for this c-Si-HJ solar cell efficiency was −0.301%/°C.

  17. Widely bandgap tunable amorphous Cd–Ga–O oxide semiconductors exhibiting electron mobilities ≥10 cm2 V−1 s−1

    International Nuclear Information System (INIS)

    Amorphous oxide semiconductors exhibit large electron mobilities; however, their bandgaps are either too large for solar cells or too small for deep ultraviolet applications depending on the materials system. Herein, we demonstrate that amorphous Cd–Ga–O semiconductors display bandgaps covering the entire 2.5–4.3 eV region while maintaining large electron mobilities ≥10 cm2 V−1 s−1. The band alignment diagram obtained by ultraviolet photoemission spectroscopy and the bandgap values reveal that these semiconductors form type-II heterojunctions with p-type Cu2O, which is suitable for solar cells and solar-blind ultraviolet sensors

  18. Optimization and Characterisation of Amorphous Iron Disilicide formed by Ion Beam Mixing of Fe/Si Multilayer Structures for Photovoltaic Applications

    International Nuclear Information System (INIS)

    This study presents an optimization and characterization of amorphous Iron Disilicide (a-FeSi2) synthesized using Ion Beam Mixing (IBM) of Fe/Si multilayer structures. The layers were deposited using RF magnetron sputtering, and subsequently irradiated with Ar+ and Fe+ beams of 150 and 200 keV. Rutherford Back Scattering (RBS) analysis was used to determine the structure and level of silicidation of the samples. The nature of the band-gap and the optical absorption coefficients were determined by optical transmission analysis. The results demonstrate that the synthesis of a-FeSi2 can be achieved using this technique, with the total level of silicidation being highly dependant upon the initial structure configuration and beam parameters. Direct band-gap energies of ∼0.90 eV have been observed for those samples with the highest levels of silicidation, with optical absorption coefficients of ∼104 cm-1. Therefore this method of fabrication has been shown to produce a-FeSi2 layers without the need for post-synthesis treatment, using established technologies without compromising the optical properties that make this material such a promising semiconductor for the photovoltaics market.

  19. Optimization and Characterisation of Amorphous Iron Disilicide formed by Ion Beam Mixing of Fe/Si Multilayer Structures for Photovoltaic Applications

    Science.gov (United States)

    Antwis, Luke; Wong, Lewis; Smith, Andy; Homewood, Kevin; Jeynes, Chris; Gwilliam, Russell

    2011-01-01

    This study presents an optimization and characterization of amorphous Iron Disilicide (a-FeSi2) synthesized using Ion Beam Mixing (IBM) of Fe/Si multilayer structures. The layers were deposited using RF magnetron sputtering, and subsequently irradiated with Ar+ and Fe+ beams of 150 and 200 keV. Rutherford Back Scattering (RBS) analysis was used to determine the structure and level of silicidation of the samples. The nature of the band-gap and the optical absorption coefficients were determined by optical transmission analysis. The results demonstrate that the synthesis of a-FeSi2 can be achieved using this technique, with the total level of silicidation being highly dependant upon the initial structure configuration and beam parameters. Direct band-gap energies of ˜0.90 eV have been observed for those samples with the highest levels of silicidation, with optical absorption coefficients of ˜104 cm-1. Therefore this method of fabrication has been shown to produce a-FeSi2 layers without the need for post-synthesis treatment, using established technologies without compromising the optical properties that make this material such a promising semiconductor for the photovoltaics market.

  20. In situ formation of dual amorphous phases with nanoscale fractal morphology by ion beam mixing in the ternary Y-Nb-Co system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.C. [Advanced Materials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Yan, H.F. [Advanced Materials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Li, J.H. [Advanced Materials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Zeng, F. [Advanced Materials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Liu, B.X. [Advanced Materials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)], E-mail: dmslbx@tsinghua.edu.cn

    2007-10-15

    Dual amorphous phases with Nb-rich and Y-rich compositions, respectively, are observed in Y{sub 25}Nb{sub 30}Co{sub 45} and Y{sub 15}Nb{sub 40}Co{sub 45} multilayered films upon ion irradiation. The interfaces of the two amorphous phases are also identified by high-resolution transmission electron microscopy associated with the Fourier transformation of the image. Interestingly, the obtained dual amorphous phases feature fractal morphology with a fractal dimension of 2.54, suggesting that the growth of the amorphous phases is through a diffusion-limited aggregation model.

  1. Influence of Vanadium Oxidation States on the Performance of V-Mg-Al Mixed-Oxide Catalysts for the Oxidative Dehydrogenation of Propane

    OpenAIRE

    Leticia Schacht; Juan Navarrete; Persi Schacht; Ramírez, Marco A.

    2010-01-01

    V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %). Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined...

  2. Application of neutron well coincidence counting for plutonium determination in mixed oxide fuel fabrication plant

    International Nuclear Information System (INIS)

    Mixed oxide (MOX) fuel is an alternative to conventional enriched uranium oxide fuel in thermal reactors. Indian interest in plutonium recycle in thermal reactors is primarily due to the need to develop alternative indigenous fuel for two boiling water reactors (BWR) at Tarapur, which are designed to use imported light enriched uranium fuel. A few MOX assemblies have been fabricated and loaded into the reactors. Neutron well coincidence counting (NWCC) system has been successfully employed to check the enrichments of PuO2 in MOX blends. NWCC has also been successfully applied in developing dry recycling process of clean rejected oxide (CRO) and dirty rejected oxide (DRO). (author)

  3. Direct imaging of octahedral distortion in a complex molybdenum vanadium mixed oxide.

    Science.gov (United States)

    Lunkenbein, Thomas; Girgsdies, Frank; Wernbacher, Anna; Noack, Johannes; Auffermann, Gudrun; Yasuhara, Akira; Klein-Hoffmann, Achim; Ueda, Wataru; Eichelbaum, Maik; Trunschke, Annette; Schlögl, Robert; Willinger, Marc G

    2015-06-01

    Complex Mo,V-based mixed oxides that crystallize in the orthorhombic M1-type structure are promising candidates for the selective oxidation of small alkanes. The oxygen sublattice of such a complex oxide has been studied by annular bright field scanning transmission electron microscopy. The recorded micrographs directly display the local distortion in the metal oxygen octahedra. From the degree of distortion we are able to draw conclusions on the distribution of oxidation states in the cation columns at different sites. The results are supported by X-ray diffraction and electron paramagnetic resonance measurements that provide integral details about the crystal structure and spin coupling, respectively. PMID:25914205

  4. Interspecies comparison of the metabolism and dosimetry of inhaled mixed oxides of plutonium and uranium

    International Nuclear Information System (INIS)

    Three studies were conducted to provide information on the biological fate, distribution of radiation doses among tissues, and implications for potential health consequences of an inhalation exposure to mixed-oxide nuclear fuel materials. In each study, Fischer-344 rats, beagle dogs, and cynomolgus monkeys inhaled one of three aerosols: 750 degrees C calcined mixed oxides of UO2 and PuO2, 1750 degrees C sintered (U,Pu)O2, or 850 degrees C calcined open-quotes pureclose quotes PuO2. These materials were collected from glove-box enclosures immediately after industrial processing of mixed-oxide fuel materials. Lung retention, tissue distribution, and mode of excretion of 238-240Pu, 241Am, and uranium (when present) were quantified by radiochemical analysis of tissue and excreta samples from animals sacrificed at selected times to 6.5 yr after inhalation exposure

  5. Effects of dietary supplementation with mineral/vitamin mix on beef meat colour and oxidation parameters

    Directory of Open Access Journals (Sweden)

    Miriam Iacurto

    2010-01-01

    Full Text Available Meat colour and oxidation parameters were investigated on Longissimus thoracis (LT muscle from Charolais young bulls fed with the same ration, based on mineral/vitamin mix supplementation, before slaughtering, for either 30 days (Mvit30 or 60 days (Mvit60. LT muscle was aged for 3, 7, 14 days. Different mineral/vitamin mix times supplementation had a significant influence on meat colour stability at the three different ageing times. Significant differences were found on Lightness value and Hue angle value. Oxidation parameters confirmed meat colour data. In fact, at 14 d ageing time, LT muscle, obtained from animals belong to the Mvit60 group, showed both Metamyoglobin percentage and thiobarbituric acid (TBA values lower than the others. Results point out that supplementation with mineral/vitamin mix before slaughtering increases meat colour stability and reduces oxidative processes which are the basis for degradative processes.

  6. Electron tunnelling into amorphous germanium and silicon.

    Science.gov (United States)

    Smith, C. W.; Clark, A. H.

    1972-01-01

    Measurements of tunnel conductance versus bias, capacitance versus bias, and internal photoemission were made in the systems aluminum-oxide-amorphous germanium and aluminium-oxide-amorphous silicon. A function was extracted which expresses the deviation of these systems from the aluminium-oxide-aluminium system.

  7. Dopant selection for control of charge carrier density and mobility in amorphous indium oxide thin-film transistors: Comparison between Si- and W-dopants

    Energy Technology Data Exchange (ETDEWEB)

    Mitoma, Nobuhiko, E-mail: MITOMA.Nobuhiko@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Kizu, Takio; Lin, Meng-Fang; Tsukagoshi, Kazuhito, E-mail: MITOMA.Nobuhiko@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044 (Japan); Aikawa, Shinya [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044 (Japan); Research Institute for Science and Technology, Kogakuin University, Hachioji, Tokyo 192-0015 (Japan); Ou-Yang, Wei [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044 (Japan); Department of Physics, Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China); Gao, Xu [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044 (Japan); Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123 (China); Fujiwara, Akihiko [Research and Utilization Division, Japan Synchrotron Radiation Research Institute/SPring-8, Sayo, Hyogo 679-5198 (Japan); Nabatame, Toshihide [MANA Foundry and MANA Advanced Device Materials Group, National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044 (Japan)

    2015-01-26

    The dependence of oxygen vacancy suppression on dopant species in amorphous indium oxide (a-InO{sub x}) thin film transistors (TFTs) is reported. In a-InO{sub x} TFTs incorporating equivalent atom densities of Si- and W-dopants, absorption of oxygen in the host a-InO{sub x} matrix was found to depend on difference of Gibbs free energy of the dopants for oxidation. For fully oxidized films, the extracted channel conductivity was higher in the a-InO{sub x} TFTs containing dopants of small ionic radius. This can be explained by a reduction in the ionic scattering cross sectional area caused by charge screening effects.

  8. Effect of Al2O3 insulator thickness on the structural integrity of amorphous indium-gallium-zinc-oxide based thin film transistors.

    Science.gov (United States)

    Kim, Hak-Jun; Hwang, In-Ju; Kim, Youn-Jea

    2014-12-01

    The current transparent oxide semiconductors (TOSs) technology provides flexibility and high performance. In this study, multi-stack nano-layers of TOSs were designed for three-dimensional analysis of amorphous indium-gallium-zinc-oxide (a-IGZO) based thin film transistors (TFTs). In particular, the effects of torsional and compressive stresses on the nano-sized active layers such as the a-IGZO layer were investigated. Numerical simulations were carried out to investigate the structural integrity of a-IGZO based TFTs with three different thicknesses of the aluminum oxide (Al2O3) insulator (δ = 10, 20, and 30 nm), respectively, using a commercial code, COMSOL Multiphysics. The results are graphically depicted for operating conditions. PMID:25971080

  9. Solvent-Free Selective Oxidation of Toluene with O2 Catalyzed by Metal Cation Modified LDHs and Mixed Oxides

    Directory of Open Access Journals (Sweden)

    Xiaoli Wang

    2016-01-01

    Full Text Available A series of metal cation modified layered-double hydroxides (LDHs and mixed oxides were prepared and used to be the selective oxidation of toluene with O2. The results revealed that the modified LDHs exhibited much higher catalytic performance than their parent LDH and the modified mixed oxides. Moreover, the metal cations were also found to play important roles in the catalytic performance and stabilities of modified catalysts. Under the optimal reaction conditions, the highest toluene conversion reached 8.7% with 97.5% of the selectivity to benzyldehyde; moreover, the catalytic performance remained after nine catalytic runs. In addition, the reaction probably involved a free-radical mechanism.

  10. A study of oxygen transport in mixed conducting oxides using isotopic exchange and conductivity relaxation

    OpenAIRE

    Otter, den, FAH

    2000-01-01

    Mixed conducting oxygen ion conductors can be applied as membranes for the separation of oxygen from air, as electrodes for both oxygen pumps and solid oxide fuel cells. In these applications, oxygen molecules dissociate on the surface of the material. The atomic oxygen species pick up two electrons each before they are incorporated in the oxygen anion sublattice. Oxygen transport through the bulk usually occurs by a hopping process. The transport of oxygen through a mixed conducting membrane...

  11. Effects of dietary supplementation with mineral/vitamin mix on beef meat colour and oxidation parameters

    OpenAIRE

    Miriam Iacurto; Sergio Gigli; Bruno Ronchi; David Meo Zilio; Katya Carbone; Federico Vincenti

    2010-01-01

    Meat colour and oxidation parameters were investigated on Longissimus thoracis (LT) muscle from Charolais young bulls fed with the same ration, based on mineral/vitamin mix supplementation, before slaughtering, for either 30 days (Mvit30) or 60 days (Mvit60). LT muscle was aged for 3, 7, 14 days. Different mineral/vitamin mix times supplementation had a significant influence on meat colour stability at the three different ageing times. Significant differences were found on Lightness value and...

  12. Oxygen potential studies on hypostoichiometric uranium-cerium mixed oxide

    Science.gov (United States)

    Nagarajan, K.; Saha, Rita; Yadav, R. B.; Rajagopalan, S.; Kutty, K. V. G.; Saibaba, M.; Rao, P. R. Vasudeva; Mathews, C. K.

    1985-02-01

    Oxygen potential measurements on (U,Ce)0 2-x with Ce/U + Ce ratios of 0.2 to 0.5 were carried out at 1073 and 1173 K by a gas equilibration method employing H 20/H 2 carrier gas. A new wet chemical method based on potentiometric titrations was used to determine and cross check the O/M ratios of the equilibrated samples. Lattice parameters of stoichiometric oxides were determined by x-ray diffraction. The oxygen potentials and their dependence on O/M and composition are discussed and compared with available literature data.

  13. Preparation and Cycling Performance of Iron or Iron Oxide Containing Amorphous Al-Li Alloys as Electrodes

    Directory of Open Access Journals (Sweden)

    Franziska Thoss

    2014-12-01

    Full Text Available Crystalline phase transitions cause volume changes, which entails a fast destroying of the electrode. Non-crystalline states may avoid this circumstance. Herein we present structural and electrochemical investigations of pre-lithiated, amorphous Al39Li43Fe13Si5-powders, to be used as electrode material for Li-ion batteries. Powders of master alloys with the compositions Al39Li43Fe13Si5 and Al39Li43Fe13Si5 + 5 mass-% FeO were prepared via ball milling and achieved amorphous/nanocrystalline states after 56 and 21.6 h, respectively. In contrast to their Li-free amorphous pendant Al78Fe13Si9, both powders showed specific capacities of about 400 and 700 Ah/kgAl, respectively, after the third cycle.

  14. NOx selective catalytic reduction at high temperatures with mixed oxides derived from layered double hydroxides

    OpenAIRE

    Palomares Gimeno, Antonio Eduardo; Franch Martí, Cristina; Ribera, Antonio; Abellán, G.

    2012-01-01

    Mixed oxides derived from layered double hydroxides (LDHs) have been investigated as potential catalysts for the NOx removal at high temperatures. The best results were obtained with Co–Al mixed oxides derived from LDHs that are active at 750 ◦C in the presence of oxygen and water. These catalysts could reduce or/and decompose the NOx formed in the dense phase of the FCC regenerator, being deactivated at oxygen concentrations higher than 1.5%. Nevertheless this deactivation is not...

  15. Visibly transparent and radiopaque inorganic organic composites from flame-made mixed-oxide fillers

    Energy Technology Data Exchange (ETDEWEB)

    Maedler, Lutz [University of California, Los Angeles, Department of Chemical Engineering (United States)], E-mail: lutz@seas.ucla.edu; Krumeich, Frank [Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences (Switzerland); Burtscher, Peter; Moszner, Norbert [Ivoclar Vivadent AG (Liechtenstein)

    2006-08-15

    Radiopaque composites have been produced from flame-made ytterbium/silica mixed oxide within a crosslinked methacrylate resin matrix. The refractive index of the filler powder increased with ytterbium oxide loading. A high transparency was achieved for a matching refractive index of the filler powder and the polymer in comparison to commercial materials with 52 wt% ceramic filling. It was demonstrated that powder homogeneity with regard to particle morphology and distribution of the individual metal atoms is essential to obtain a highly transparent composite. In contrast, segregation of crystalline single-oxide phases drastically decreased the composite transparency despite similar specific surface areas, refractive indices and overall composition. The superior physical strength, transparency and radiopacity compared to composites made from conventional silica based-fillers makes the flame-made mixed-oxide fillers especially attractive for dental restoration materials.

  16. Hydrogenated amorphous silicon oxide containing a microcrystalline silicon phase and usage as an intermediate reflector in thin-film silicon solar cells

    OpenAIRE

    Lambertz, A.; Grundler, T.; F. Finger

    2011-01-01

    To further improve the stability of amorphous/microcrystalline silicon (a-Si:H/mu c-Si:H) tandem solar cells, it is important to reduce the thickness of the a-Si: H top cell. This can be achieved by introduction of an intermediate reflector between the a-Si: H top and the mu c-Si: H bottom cell which reflects light back into the a-Si: H cell and thus, increases its photocurrent at possibly reduced thickness. Microcrystalline silicon oxide (mu c-SiOx:H) is used for this purpose and the trade-o...

  17. Bias-induced migration of ionized donors in amorphous oxide semiconductor thin-film transistors with full bottom-gate and partial top-gate structures

    Directory of Open Access Journals (Sweden)

    Mallory Mativenga

    2012-09-01

    Full Text Available Bias-induced charge migration in amorphous oxide semiconductor thin-film transistors (TFTs confirmed by overshoots of mobility after bias stressing dual gated TFTs is presented. The overshoots in mobility are reversible and only occur in TFTs with a full bottom-gate (covers the whole channel and partial top-gate (covers only a portion of the channel, indicating a bias-induced uneven distribution of ionized donors: Ionized donors migrate towards the region of the channel that is located underneath the partial top-gate and the decrease in the density of ionized donors in the uncovered portion results in the reversible increase in mobility.

  18. Magnetic behavior of Mg-Al-Zn-Fe mixed oxides from precursors layered double hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Oliva, M.I., E-mail: marcosivanoliva@gmail.com [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, M. Allende y H. de la Torre Ciudad Universitaria, 5000 Cordoba (Argentina); IFFAM AF (CONICET - FaMAF UNC), M. Allende y H. de la Torre Ciudad Universitaria, 5000 Cordoba (Argentina); Heredia, A. [CITeQ - Facultad R. Cordoba, Universidad Tecnologica Nacional Maestro Lopez esq. Cruz Roja Argentina, CP 5016 Cordoba (Argentina); Zandalazini, C.I. [Centro Laser de Ciencias Moleculares. INFIQC-FCQ-Grupo de Ciencia de Materiales-FaMAF-Universidad Nacional de Cordoba, Ciudad Universitaria, CP5000 Cordoba, Argentina CONICET (Argentina); Crivello, M. [CITeQ - Facultad R. Cordoba, Universidad Tecnologica Nacional Maestro Lopez esq. Cruz Roja Argentina, CP 5016 Cordoba (Argentina); Corchero, E. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, M. Allende y H. de la Torre Ciudad Universitaria, 5000 Cordoba (Argentina)

    2012-08-15

    Mixed oxides of Mg-Al-Zn-Fe were obtained by calcination of layered double hydroxides (LDH) prepared by coprecipitation reaction with hydrothermal treatment. The structural characterization of precursors and oxides was carried out by X rays diffraction, showing increases of ZnO phase with the increase of the zinc content. Magnetic behavior was studied by vibrating sample magnetometer (VSM) and by a superconducting quantum interference device (SQUID) showing both paramagnetic and super paramagnetic behavior depending on both particles size and composition.

  19. Thermal expansion and heat capacity measurement of uranium-thorium-dysprosium mixed oxides

    International Nuclear Information System (INIS)

    Dysprosium showed 40 at. % solubility in (U0.2Th0.8)O2.00 forming Face centered cubic solid solutions. XRD analysis showed that lattice parameter of mixed oxides decrease whereas average linear thermal expansion coefficients obtained using high temperature X-ray diffractometer (HTXRD) increase with increase in Dy content. Heat capacity measurements of oxides were carried out using Differential Scanning Calorimetry (DSC) in the temperature range 300-850 K. (author)

  20. Ni–Ta–O mixed oxide catalysts for the low temperature oxidative dehydrogenation of ethane to ethylene

    KAUST Repository

    Zhu, Haibo

    2015-09-01

    The "wet" sol-gel and "dry" solid-state methods were used to prepare Ni-Ta-O mixed oxide catalysts. The resulting Ni-Ta oxides exhibit high activity and selectivity for the low temperature oxidative dehydrogenation of ethane to ethylene. The Ta/(Ni + Ta) atomic ratios (varying from 0 to 0.11 in "wet" sol-gel method, and from 0 to 0.20 in "dry" solid-state method) as well as the preparation methods used in the synthesis, play important roles in controlling catalyst structure, activity, selectivity and stability in the oxidative dehydrogenation of ethane. Electron microscopy characterizations (TEM, EELS mapping, and HAADF-STEM) clearly demonstrate that the Ta atoms are inserted into NiO crystal lattice, resulting in the formation of a new Ni-Ta oxide solid solution. More Ta atoms are found to be located at the lattice sites of crystal surface in sol-gel catalyst. While, a small amount of thin layer of Ta2O5 clusters are detected in solid-state catalyst. Further characterization by XRD, N2 adsorption, SEM, H2-TPR, XPS, and Raman techniques reveal different properties of these two Ni-Ta oxides. Due to the different properties of the Ni-Ta oxide catalysts prepared by two distinct approaches, they exhibit different catalytic behaviors in the ethane oxidative dehydrogenation reaction at low temperature. Thus, the catalytic performance of Ni-Ta-O mixed oxide catalysts can be systematically modified and tuned by selecting a suitable synthesis method, and then varying the Ta content. ©2015 Elsevier Inc. All rights reserved.

  1. Decommissioning of a mixed oxide fuel fabrication facility

    International Nuclear Information System (INIS)

    Decommissioning of the coprecipitation plant, which made plutonium/uranium oxide fuel, is a lead project in the BNFL Sellafield decommissioning programme. The overall programme has the objectives of gaining data and experience in a wide range of decommissioning operations and hence in this specific project to pilot the decommissioning of plant heavily contaminated with plutonium and other actinides. Consequently the operations have been used to test improvements in temporary containment, contamination control and decontamination methods and also to develop in situ plutonium assay, plutonium recovery and size-reduction methods. Finally the project is also yielding data on manpower requirements, personnel radiation uptake and waste arisings to help in the planning of future decommissioning projects

  2. Comparative study of structural, optical and impedance measurements on V{sub 2}O{sub 5} and V-Ce mixed oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Malini, D. Rachel [Department of Physics, The American College, Madurai-625 012 (India); Sanjeeviraja, C., E-mail: sanjeeviraja@rediffmail.com [Department of Physic, Alagappa Chettiar College of Engg. & Tech., Karaikudi-630 004 (India)

    2015-06-24

    Vanadium pentoxide (V{sub 2}O{sub 5}) and Vanadium-Cerium mixed oxide thin films at different molar ratios of V{sub 2}O{sub 5} and CeO{sub 2} have been deposited at 200 W rf power by rf planar magnetron sputtering in pure argon atmosphere. The structural and optical properties were studied by taking X-ray diffraction and transmittance and absorption spectra respectively. The amorphous thin films show an increase in transmittance and optical bandgap with increase in CeO{sub 2} content in as-prepared thin films. The impedance measurements for as-deposited thin films show an increase in electrical conductivity with increase in CeO{sub 2} material.

  3. A study of oxygen transport in mixed conducting oxides using isotopic exchange and conductivity relaxation

    NARCIS (Netherlands)

    Otter, den Matthijs Willem

    2000-01-01

    Mixed conducting oxygen ion conductors can be applied as membranes for the separation of oxygen from air, as electrodes for both oxygen pumps and solid oxide fuel cells. In these applications, oxygen molecules dissociate on the surface of the material. The atomic oxygen species pick up two electrons

  4. Photo-induced low temperature synthesis of nanocrystalline UO2, ThO2 and mixed UO2-ThO2 oxides

    Science.gov (United States)

    Pavelková, Tereza; Čuba, Václav; Šebesta, Ferdinand

    2013-11-01

    Photochemically induced preparation of nanocrystalline uranium and/or thorium oxides is based on UV radiation induced formation of amorphous solid precursor in aqueous solutions containing uranium and/or thorium nitrate and ammonium formate. Subsequent heat treatment under various atmospheres leads to formation of nanocrystalline UO2, ThO2 or UO2-ThO2 solid solution at minimum temperatures in the interval 300-550 °C. The materials consist of nanoparticles from 3 to 15 nm in diameter and with narrow size distribution. The initial solutions contain soluble salts of respective metals and OH radical scavenger (ammonium formate) satisfying the "CHON principle". Solutions may be used without further adjustment (e.g. saturation by inert gases or adjusting pH). Photo-induced precipitation proceeds at room temperature and does not require strict control of reaction conditions (pH, temperature). Due to negligible amounts of carbon in solid precursor formed from any solution, it is possible to prepare crystalline nanomaterials containing U(IV) oxide from solid precursors directly via heat treatment in Ar + H2 atmosphere without pre-calcination in air. Mild heat treatment (450-550 °C) results in formation of oxides with well-developed nanocrystals. In the case of mixed oxides, high level of interaction of both components was observed, resulting in the formation of solid solution U0.56Th0.44O2 at 300 °C or higher.

  5. Electrospun mixed oxide photocatalysts to decompose dyes in water

    Science.gov (United States)

    Divya, Sherlyn

    In this work, four catalysts have been studied for their photocatalytic efficiency by testing each with methylene blue dye solution. Three catalysts were synthesized by the electrospinning method and then compared with the fourth commercially available catalyst for their photocatalytic activity. The basic metal oxide studied was titanium dioxide. Nanocomposite mats of pure titania, copper doped titania and copper doped degussa P25 titania, were synthesized using the electrospinning method. The pure titania and copper doped titania nanocomposites possessed the anatase phase which was obtained by annealing the as-spun nanocomposites at 4500C. All the catalysts were analyzed for their photocatalytic activity both under ultra-violet light and under visible light. The aim of this work was to synthesize titania photocatalysts, demonstrate their photocatalytic activity with methylene blue solution under UV-light and visible light and compare their activities with the commercial titanium dioxide (degussa P25). It is important to synthesize visible light active photocatalysts as these could be activated under a wide spectrum of natural sunlight unlike the degussa titanium dioxide. Doping was incorporated in order to narrow the band gap energy of the photocatalyst for achieving higher efficiency especially under visible light irradiation. The morphology and size of the synthesized photocatalysts were studied by characterizing them with Scanning Electron Microscopy, Energy Dispersive X-Ray Spectroscopy, Transmission Electron Microscopy and X-Ray Diffraction. The photocatalytic activity tests were carried out using UV-Vis Spectroscopy. It was found that the electrospun pure titania and copper doped titania fibers were activated under the visible light spectrum unlike the degussa titanium dioxide. The copper doped titania provided to be the most efficient photocatalyst under visible light radiation and the importance of this finding can be extended for treating industrial

  6. Synthesis of Coral-Like Tantalum Oxide Films via Anodization in Mixed Organic-Inorganic Electrolytes

    Science.gov (United States)

    Yu, Hongbin; Zhu, Suiyi; Yang, Xia; Wang, Xinhong; Sun, Hongwei; Huo, Mingxin

    2013-01-01

    We report a simple method to fabricate nano-porous tantalum oxide films via anodization with Ta foils as the anode at room temperature. A mixture of ethylene glycol, phosphoric acid, NH4F and H2O was used as the electrolyte where the nano-porous tantalum oxide could be synthesized by anodizing a tantalum foil for 1 h at 20 V in a two–electrode configuration. The as-prepared porous film exhibited a continuous, uniform and coral-like morphology. The diameters of pores ranged from 30 nm to 50 nm. The pores interlaced each other and the depth was about 150 nm. After calcination, the as-synthesized amorphous tantalum oxide could be crystallized to the orthorhombic crystal system. As observed in photocatalytic experiments, the coral-like tantalum oxide exhibited a higher photocatalytic activity for the degradation of phenol than that with a compact surface morphology, and the elimination rate of phenol increased by 66.7%. PMID:23799106

  7. Synthesis of coral-like tantalum oxide films via anodization in mixed organic-inorganic electrolytes.

    Directory of Open Access Journals (Sweden)

    Hongbin Yu

    Full Text Available We report a simple method to fabricate nano-porous tantalum oxide films via anodization with Ta foils as the anode at room temperature. A mixture of ethylene glycol, phosphoric acid, NH4F and H2O was used as the electrolyte where the nano-porous tantalum oxide could be synthesized by anodizing a tantalum foil for 1 h at 20 V in a two-electrode configuration. The as-prepared porous film exhibited a continuous, uniform and coral-like morphology. The diameters of pores ranged from 30 nm to 50 nm. The pores interlaced each other and the depth was about 150 nm. After calcination, the as-synthesized amorphous tantalum oxide could be crystallized to the orthorhombic crystal system. As observed in photocatalytic experiments, the coral-like tantalum oxide exhibited a higher photocatalytic activity for the degradation of phenol than that with a compact surface morphology, and the elimination rate of phenol increased by 66.7%.

  8. Partial oxidation of methane to syngas in a mixed-conducting oxygen permeable membrane reactor

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Mixed-conducting oxygen permeable membranes represent a class of novel ceramic membranes, which exhibit mixed oxygen ionic and electronic conductivities. At high temperatures, oxygen can permeate through the membrane from the high to low oxygen pressure side under an oxygen concentration gradient. Theoretically, the permselectivity of oxygen is 100%. Recently, a novel mixed-conducting membrane--Ba0.5Sr0.5Co0.8Fe0.2O3-δ has been developed, which shows extremely high oxygen permeability and promising stability. Furthermore, the reactor made with such membranes was successfully applied to the partial oxidation of methane to syngas reaction using air as the oxygen source, which realized the coupling of the separation of oxygen from air and the partial oxidation of membrane reaction in one process. At 850℃, methane conversion >88%, CO selectivity >97% and oxygen permeation rate of about 7.8 mL/(cm2.min) were obtained.

  9. A facile solution combustion synthesis of nanosized amorphous iron oxide incorporated in a carbon matrix for use as a high-performance lithium ion battery anode material

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Chunyu, E-mail: chunyu6zhu@gmail.com; Saito, Genki; Akiyama, Tomohiro

    2015-06-05

    Highlights: • Iron oxide–carbon composite was fabricated by facile solution combustion synthesis. • Iron oxide nanoparticles of about 5 nm were uniformly embedded in dense carbon matrix. • The composite exhibited enhanced cyclability and rate capability. • A high capacity of 687 mA h g{sup −1} after 200 cycles at a current rate of 0.5 A g{sup −1} were obtained. - Abstract: An amorphous iron oxide–carbon composite has been fabricated through an effective, inexpensive, and scalable method employing solution combustion synthesis. Amorphous iron oxide nanoparticles with diameters of about 5 nm were synthesized and uniformly embedded in a dense carbon matrix. The synthesized composite exhibits enhanced cyclability and rate capability, showing a high reversible capacity of 687 mA h g{sup −1} after 200 discharge/charge cycles at a current rate of 0.5 A g{sup −1}, compared to the 400 mA h g{sup −1} observed for Fe{sub 2}O{sub 3} nanoparticles. This enhanced performance was retained despite more demanding conditions, delivering a high capacity of about 525 mA h g{sup −1} and a nearly perfect coulombic efficiency even after 400 cycles at 1 A g{sup −1}. The easy production and superior electrochemical properties of this composite suggest that it is a promising material for use as an anode material in high performance lithium ion batteries.

  10. Homogeneous double-layer amorphous Si-doped indium oxide thin-film transistors for control of turn-on voltage

    Science.gov (United States)

    Kizu, Takio; Aikawa, Shinya; Nabatame, Toshihide; Fujiwara, Akihiko; Ito, Kazuhiro; Takahashi, Makoto; Tsukagoshi, Kazuhito

    2016-07-01

    We fabricated homogeneous double-layer amorphous Si-doped indium oxide (ISO) thin-film transistors (TFTs) with an insulating ISO cap layer on top of a semiconducting ISO bottom channel layer. The homogeneously stacked ISO TFT exhibited high mobility (19.6 cm2/V s) and normally-off characteristics after annealing in air. It exhibited normally-off characteristics because the ISO insulator suppressed oxygen desorption, which suppressed the formation of oxygen vacancies (VO) in the semiconducting ISO. Furthermore, we investigated the recovery of the double-layer ISO TFT, after a large negative shift in turn-on voltage caused by hydrogen annealing, by treating it with annealing in ozone. The recovery in turn-on voltage indicates that the dense VO in the semiconducting ISO can be partially filled through the insulator ISO. Controlling molecule penetration in the homogeneous double layer is useful for adjusting the properties of TFTs in advanced oxide electronics.

  11. Bimetallic bonding and mixed oxide formation in the Ga-Pd-CeO2 system

    Science.gov (United States)

    Skála, Tomáš; Tsud, Nataliya; Prince, Kevin C.; Matolín, Vladimír

    2011-08-01

    The interaction of gallium and palladium with 2 nm CeO2(111) layers grown on Cu(111) was studied by core level photoelectron spectroscopy and resonant valence band spectroscopy. Palladium alone interacted weakly with ceria layers. Gallium deposited on cerium dioxide formed a mixed Ga2O3-Ce2O3 oxide of 1:1 stoichiometry (cerium gallate CeGaO3), with both metals in the M3+ oxidation state. Increasing Ga coverages led to the formation of lower oxidation states, i.e., Ga1+ in Ga2O oxide and metallic Ga0. Palladium deposited onto this complex system interacted with gallium leading to a breakage of Ga-ceria bonds, a decrease of the oxidation state of gallium, and formation of a Ga-Pd intermetallic alloy in which all components (CeO2, CeGaO3, Ga2O, Ga-Pd, and Pd) are in equilibrium.

  12. Influence of vanadium oxidation states on the performance of V-Mg-Al mixed-oxide catalysts for the oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Schacht, L. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Ciencia de Materiales, Av. IPN s/n, Edificio 9, Col. Lindavista, 07738 Mexico D. F. (Mexico); Navarrete, J.; Schacht, P.; Ramirez, M. A., E-mail: pschacha@imp.m [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D. F. (Mexico)

    2010-07-01

    V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %) Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined by the Mg/Al ratio. Vanadium interlayer doping modifies the oxidation state of vanadium and consequently catalytic properties. Surface properties were studied by X-ray photoelectron spectroscopic and diffuse reflectance, UV-visible spectroscopy, and temperature programmed reduction. The analyses provided information about the oxidation state, before and after the reaction. From these results, it is suggested that selectivity to propylene and catalytic activity depend mainly of vanadium oxidation state. (Author)

  13. Oxidation and Reduction Behaviors of Plutonium and Uranium Mixed Oxide Powders

    International Nuclear Information System (INIS)

    As research and development activities for MOX fuel pellet production, oxidation and reduction behaviors of MOX powders were investigated by thermogravimetry and X-ray diffraction measurements. It was observed that the oxidation limit decreased with oxidizing temperature and Pu content. The MOX powders showed a two-step oxidation and kinetic stability under non-stoichiometry. The oxidation rates were evaluated from the isothermal oxidation tests. It was found that the reduction temperature of M4O9 + M3O8 was higher than that of M4O9. This indicated that the reduction of M4O9 was prevented by the existence of M3O8. Activation energy of the reduction was derived from the non-isothermal reduction tests. The data are expected to contribute to establishing a control technique for O/M ratio during MOX powder storage and pellet production. (author)

  14. Fabrication of uranium–americium mixed oxide pellet from microsphere precursors: Application of CRMP process

    Energy Technology Data Exchange (ETDEWEB)

    Remy, E. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Picart, S., E-mail: sebastien.picart@cea.fr [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Delahaye, T. [Fuel Cycle Technology Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Jobelin, I. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Lebreton, F.; Horlait, D. [Fuel Cycle Technology Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Bisel, I. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Blanchart, P. [Heterogeneous Materials Research Group, Centre Européen de la Céramique, F-87068 Limoges (France); Ayral, A. [Institut Européen des Membranes, CNRS-ENSCM-UM2, CC47, University Montpellier 2, F-34095 Montpellier cedex 5 (France)

    2014-10-15

    Highlights: • Dust free process for (U,Am)O{sub 2} transmutation target fabrication. • Synthesis of U{sub 0.9}Am{sub 0.1}O{sub 2} mixed oxide microspheres from ion exchange resin. • Fabrication of dense U{sub 0.9}Am{sub 0.1}O{sub 2} pellet with 95% TD from mixed oxide microspheres. - Abstract: Mixed uranium–americium oxides are one of the materials envisaged for Americium Bearing Blankets dedicated to transmutation in fast neutron reactors. Recently, several processes have been developed in order to validate fabrication flowchart in terms of material specifications such as density and homogeneity but also to suggest simplifications for lowering industrial costs and hazards linked to dust generation of highly contaminating and irradiating compounds. This study deals with the application of an innovative route using mixed oxide microspheres obtained from metal loaded resin bead calcination, called Calcined Resin Microsphere Pelletization (CRMP). The synthesis of mixed oxide microsphere precursor of U{sub 0.9}Am{sub 0.1}O{sub 2±δ} is described as well as its characterisation. The use of this free-flowing precursor allows the pressing and sintering of one pellet of U{sub 0.9}Am{sub 0.1}O{sub 2±δ}. The ceramic obtained was characterised and results showed that its microstructure is dense and homogeneous and its density attains 95% of the theoretical density. This study validates the scientific feasibility of the CRMP process applied to the fabrication of uranium and americium-containing materials.

  15. Automation of remote handling in uranium and mixed oxide fuel element fabrication plants

    International Nuclear Information System (INIS)

    The subject of the analyses are plants for the fabrication or uranium oxide and uranium-plutonium mixed oxide fuel elements. The reference basis of the paper is an overview of the state-of-the-art of manufacturing technologies with regard to automation and remote handling during fuel element fabrication in national and foreign plants, and in comparabel sectors of conventional technologies. Proceeding from ambient dose rates, residence times, and technical conditions or individual doses at typical work-places during fuel element fabrication, work processes are pointed out which, taking into account technical possibilities, should be given priority when automating, and technical solutions for it are sought. Advantages and disadvantages of such measures are outlined, and reduction of radiation exposure is shown (example: mixed oxide fuel fabrication plant at Hanau). (orig./HP)

  16. The Chemical Capacitance as a Fingerprint of Defect Chemistry in Mixed Conducting Oxides.

    Science.gov (United States)

    Fleig, Juergen; Schmid, Alexander; Rupp, Ghislain M; Slouka, Christoph; Navickas, Edvinas; Andrejs, Lukas; Hutter, Herbert; Volgger, Lukas; Nenning, Andreas

    2016-01-01

    The oxygen stoichiometry of mixed conducting oxides depends on the oxygen chemical potential and thus on the oxygen partial pressure in the gas phase. Also voltages may change the local oxygen stoichiometry and the amount to which such changes take place is quantified by the chemical capacitance of the sample. Impedance spectroscopy can be used to probe this chemical capacitance. Impedance measurements on different oxides ((La,Sr)FeO3-δ = LSF, Sr(Ti,Fe)O3-δ = STF, and Pb(Zr,Ti)O3 = PZT) are presented, and demonstrate how the chemical capacitance may affect impedance spectra in different types of electrochemical cells. A quantitative analysis of the spectra is based on generalized equivalent circuits developed for mixed conducting oxides by J. Jamnik and J. Maier. It is discussed how defect chemical information can be deduced from the chemical capacitance. PMID:27640378

  17. Effect of cooling rate on achieving thermodynamic equilibrium in uranium-plutonium mixed oxides

    Science.gov (United States)

    Vauchy, Romain; Belin, Renaud C.; Robisson, Anne-Charlotte; Hodaj, Fiqiri

    2016-02-01

    In situ X-ray diffraction was used to study the structural changes occurring in uranium-plutonium mixed oxides U1-yPuyO2-x with y = 0.15; 0.28 and 0.45 during cooling from 1773 K to room-temperature under He + 5% H2 atmosphere. We compare the fastest and slowest cooling rates allowed by our apparatus i.e. 2 K s-1 and 0.005 K s-1, respectively. The promptly cooled samples evidenced a phase separation whereas samples cooled slowly did not due to their complete oxidation in contact with the atmosphere during cooling. Besides the composition of the annealing gas mixture, the cooling rate plays a major role on the control of the Oxygen/Metal ratio (O/M) and then on the crystallographic properties of the U1-yPuyO2-x uranium-plutonium mixed oxides.

  18. Synergy of FexCe1-xO2 mixed oxides for N2O decomposition

    NARCIS (Netherlands)

    Perez-Alonso, FJ; Melian Cabrera, Ignacio; Granados, ML; Kapteijn, F; Fierro, JLG

    2006-01-01

    Fe-Ce mixed oxides prepared by coprecipitation showed considerable synergy in N2O decomposition when compared with pure metal oxide counterparts. The mixed system also displayed higher stability in reaction at high temperature. Through characterisation by XRD, XPS and TPR, the activity-stability imp

  19. Method of producing homogeneous mixed metal oxides and metal-metal oxide mixtures

    International Nuclear Information System (INIS)

    A method for preparing particulate metal or metal oxide of controlled partile size comprises contacting an an aqueous solution containing dissolved metal values with excess urea at a temperature sufficient to cause urea to react with water to provide a molten urea solution containing the metal values; heating the molten urea solution to cause the metal values to precipitate, forming a mixture containing precipitated metal values; heating the mixture containing precipitated metal values to evaporate volatile material leaving a dry powder containing said metal values. The dry powder can be calcined to provide particulate metal oxide or reduced to provide particulate metal. Oxide mixtures are provided when the aqueous solution contains values of more than one metal. Homogeneousmetal-metal oxide mistures for preparing cermets can be prepared by selectively reducing at least one of the metal oxides. (auth)

  20. A mixed proton-oxide ion-electron conducting anode for highly coking-resistant solid oxide fuel cells

    International Nuclear Information System (INIS)

    Highlights: • A multi-phase mixed proton-oxide ion-electron conducting anode was employed. • BaO/Ni interfaces facilitate water-mediated carbon removal. • Fast oxygen ions flux and formed water are favorable for hydrocarbon reformation. - Abstract: A multi-phase mixed proton-oxide ion-electron conducting composite is employed as a new anode material for a coking-resistant solid oxide fuel cell (SOFC) based on oxide ion conducting electrolyte, operated in methane and ethanol. The formation of BaO/Ni interfaces can effectively readily adsorb water and facilitate water-mediated carbon removal. The fast oxygen ions flux and formed steam at anode side are also found to be favorable for hydrocarbon reformation to promote the cell performance and long term stability. At 700 °C, maximum power densities of 580 and 368 mW cm−2 are achieved in methane and ethanol, respectively. The resistance against carbon deposition is significantly improved, showing stable voltage in 120 h durability test

  1. Soft chemical control of the crystal and magnetic structure of a layered mixed valent manganite oxide sulfide

    Directory of Open Access Journals (Sweden)

    Jack N. Blandy

    2015-04-01

    Full Text Available Oxidative deintercalation of copper ions from the sulfide layers of the layered mixed-valent manganite oxide sulfide Sr2MnO2Cu1.5S2 results in control of the copper-vacancy modulated superstructure and the ordered arrangement of magnetic moments carried by the manganese ions. This soft chemistry enables control of the structures and properties of these complex materials which complement mixed-valent perovskite and perovskite-related transition metal oxides.

  2. Degradation of organophosphorus pesticide parathion methyl on nanostructured titania-iron mixed oxides

    Science.gov (United States)

    Henych, Jiří; Štengl, Václav; Slušná, Michaela; Matys Grygar, Tomáš; Janoš, Pavel; Kuráň, Pavel; Štastný, Martin

    2015-07-01

    Titania-iron mixed oxides with various Ti:Fe ratio were prepared by homogeneous hydrolysis of aqueous solutions of titanium(IV) oxysulphate and iron(III) sulphate with urea as a precipitating agent. The synthesized samples were characterized by X-ray diffraction, Raman and infrared spectroscopy, scanning and transmission electron microscopy, XRF analysis, specific surface area (BET) and porosity determination (BJH). These oxides were used for degradation of organophosporus pesticide parathion methyl. The highest degradation efficiency approaching degraded on the surfaces of pure oxides. In general, the highest degradation rate exhibited samples consisted of the iron or titanium oxide containing a moderate amount of the admixture. However, distinct correlations between the degradation rate and the sorbent composition were not identified.

  3. A hybrid water-splitting cycle using copper sulfate and mixed copper oxides

    Science.gov (United States)

    Schreiber, J. D.; Remick, R. J.; Foh, S. E.; Mazumder, M. M.

    1980-01-01

    The Institute of Gas Technology has derived and developed a hybrid thermochemical water-splitting cycle based on mixed copper oxides and copper sulfate. Similar to other metal oxide-metal sulfate cycles that use a metal oxide to 'concentrate' electrolytically produced sulfuric acid, this cycle offers the advantage of producing oxygen (to be vented) and sulfur dioxide (to be recycled) in separate steps, thereby eliminating the need of another step to separate these gases. The conceptual process flow-sheet efficiency of the cycle promises to exceed 50%. It has been completely demonstrated in the laboratory with recycled materials. Research in the electrochemical oxidation of sulfur dioxide to produce sulfuric acid and hydrogen performed at IGT indicates that the cell performance goals of 200 mA/sq cm at 0.5 V will be attainable using relatively inexpensive electrode materials.

  4. Application of mechanochemical activation for synthesis of uranium-lanthanoid mixed oxides

    International Nuclear Information System (INIS)

    The applicability of mechanochemistry to produce uranium-lanthanoid mixed oxides is presented. Phase homogeneous uranium-cerium solid solutions of the type Cex U1-x O2 (x = 0.3 / 0.95) and polyphase systems containing Lay U1-y O2+x (y = 0.12) were prepared by mechanochemical activation in air of sol-gel produced precursors. The possibility for synthesis of urania-lanthania solid solution by mechanochemical interaction of La2O3 with sol-gel produced U (IV,VI) oxide is established. The crystal structures of the obtained oxides before and after the mechanochemical treatment are analysed by the use of X-ray diffraction method. The size of the crystallites (8-16 nm), lattice parameters, crystallite strains and densities of the oxides are calculated by BRASS program for Rietveld calculation. (author)

  5. Selection of mixed conducting oxides for oxidative dehydrogenation of propane with pulse experiments

    NARCIS (Netherlands)

    Crapanzano, Salvatore; Babich, Igor V.; Lefferts, Leon

    2011-01-01

    In this study, propane pulse experiments at 550 °C are used as a method to select suitable oxides for further operation of catalytic dense membrane reactor (CDMR) for oxidative dehydrogenation of propane. Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF), La2NiO4+δ (LN) and PrBaCo2O5+δ (PBC) powders were used as mode

  6. Role of cerium-zirconium mixed oxides as catalysts for car pollution: a short review

    International Nuclear Information System (INIS)

    This article focuses on the role of mixed oxides in the Ce-Zr-O system, which is important as an excellent promoter for oxygen storage capacity in automotive three-way catalysts. In a model of Pt-alumina catalysts, there is a clear effect of CeO2-ZrO2 solid solution on NO and CO removal activities under dynamic air/fuel conditions. It is suggested that the design and development of automotive catalyst can be realized through research on complex oxides in Ce-Zr-O and related systems. (orig.)

  7. XPS study of surface absorbed oxygen of ABO3 mixed oxides

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xin; YANG Qiuhua; CUI Jinjin

    2008-01-01

    Perovskite-type complex oxides ABO3 (A=Sr, La;B=Mn, Fe, Co) were prepared by citric acid method. The degradation of water-solubilized dyes was carried out using the mixed oxides as photocatalyst. The surface absorbed oxygen was analyzed using X-ray photoelectron spectroscopy (XPS). The results indicated that there was a relationship between the photocatalytic activity and the content of the surface absorbed oxygen. The higher the content of the surface absorbed oxygen was, the better the performance of the photocatalyst.

  8. STUDY ON SEGMENTED POLYURETHANE WITH MIXED SOFT SEGMENTS OF POLYCHLOROMETHYL METHYL SILOXANE AND POLYTETRAMETHYLENE OXIDE

    Institute of Scientific and Technical Information of China (English)

    JIANG Xiqun; YANG Changzheng; YU Xuehai

    1994-01-01

    Two series of polyurethanes based on mixed polychloromethyl methyl siloxane and polytetramethylene oxide in different weight fractions were synthesized. The phase separation of samples was studied using DSC and dynamic mechanical property analysis. The results showed that the introduction of chloromethyl group into polysiloxane increased its polarity and hence improved the miscibilities with polytetramethylene oxide and polyurethane hard segment.Particularly, in the case of N-methyldiethanolamine extended materials, the surface and tensile properties of these samples can be adjusted by various ratios of two soft segments.

  9. Reliability of fast reactor mixed-oxide fuel during operational transients

    International Nuclear Information System (INIS)

    Results are presented from the cooperative U.S. Department of Energy (DOE) and Power Reactor and Nuclear Fuel Development Corporation of Japan (PNC) Phase I and II operational transient testing program conducted in the EBR-II reactor. The program includes second-generation (D9 and PNC 316 claddings) and more advanced (ferritic martensitic alloy, 20 % Ni austenitic stainless steel, and oxide-dispersion-strengthened ferritic stainless steel claddings) mixed-oxide fuel pins. The irradiation tests include duty-cycle operation and extended overpower tests. The results demonstrate the capability of second-generation fuel pins to survive a wide range of duty-cycle and extended overpower events. (author)

  10. Reaction pathways for catalytic gas-phase oxidation of glycerol over mixed metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Suprun, W.; Glaeser, R.; Papp, H. [Leipzig Univ. (Germany). Inst. of Chemical Technology

    2011-07-01

    Glycerol as a main by-product from bio-diesel manufacture is a cheap raw material with large potential for chemical or biochemical transformations to value-added C3-chemicals. One possible way of glycerol utilization involves its catalytic oxidation to acrylic acid as an alternative to petrochemical routes. However, this catalytic conversion exhibits various problems such as harsh reaction conditions, severe catalyst coking and large amounts of undesired by-products. In this study, the reaction pathways for gas-phase conversion of glycerol over transition metal oxides (Mo, V und W) supported on TiO{sub 2} and SiO{sub 2} were investigated by two methods: (i) steady state experiments of glycerol oxidation and possible reactions intermediates, i.e., acrolein, 3-hydroxy propionaldehyde and acetaldehyde, and (ii) temperature-programmed surface reaction (TPSR) studies of glycerol conversion in the presence and in the absence of gas-phase oxygen. It is shown that the supported W-, V and Mo-oxides possess an ability to catalyze the oxidation of glycerol to acrylic acid. These investigations allowed us to gain a deeper insight into the reaction mechanism. Thus, based on the obtained results, three possible reactions pathways for the selective oxidation of glycerol to acrylic acid on the transition metal-containing catalysts are proposed. The major pathways in presence of molecular oxygen are a fast successive destructive oxidation of glycerol to CO{sub x} and the dehydration of glycerol to acrolein which is a rate-limiting step. (orig.)

  11. Self-aligned top-gate amorphous indium zinc oxide thin-film transistors exceeding low-temperature poly-Si transistor performance.

    Science.gov (United States)

    Park, Jae Chul; Lee, Ho-Nyeon; Im, Seongil

    2013-08-14

    Thin-film transistor (TFT) is a key component of active-matrix flat-panel displays (AMFPDs). These days, the low-temperature poly silicon (LTPS) TFTs are to match with advanced AMFPDs such as the active matrix organic light-emitting diode (AMOLED) display, because of their high mobility for fast pixel switching. However, the manufacturing process of LTPS TFT is quite complicated, costly, and scale-limited. Amorphous oxide semiconductor (AOS) TFT technology is another candidate, which is as simple as that of conventioanl amorphous (a)-Si TFTs in fabrication but provides much superior device performances to those of a-Si TFTs. Hence, various AOSs have been compared with LTPS for active channel layer of the advanced TFTs, but have always been found to be relatively inferior to LTPS. In the present work, we clear the persistent inferiority, innovating the device performaces of a-IZO TFT by adopting a self-aligned coplanar top-gate structure and modifying the surface of a-IZO material. Herein, we demonstrate a high-performance simple-processed a-IZO TFT with mobility of ∼157 cm(2) V(-1) s(-1), SS of ∼190 mV dec(-1), and good bias/photostabilities, which overall surpass the performances of high-cost LTPS TFTs. PMID:23823486

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

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

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

  13. Thermal conductivity of hypostoichiometric low Pu content (U,Pu)O2-x mixed oxide

    International Nuclear Information System (INIS)

    The 'laser flash' method was used to measure the thermal diffusivity of PWR mixed oxide fuels with Pu contents ranging from 3 to 15 wt% and oxygen to metal ratio (O/M) ranging from 2.00 to ∼1.95. The temperature range extends from 700 to 2300 K. The fuel thermal conductivity is derived using heat capacity values of the mixed oxides calculated by Kopp's law from recommended values for the heat capacities of UO2, PuO2 and O2. We observe an effect of the deviation from stoichiometry on the conductivity smaller than what is recommended for high plutonium content FBR fuel. Our results are fitted in the low temperature range to a classical phonon transport model. Abeles's simplified theory of phonon diffusion by point defects is used to discuss the results. We propose a new thermal conductivity relation, which takes into account the effect of the O/M ratio

  14. Sol-gel synthesis and characterization of mesoporous iron-titanium mixed oxide for catalytic application

    International Nuclear Information System (INIS)

    A mixed phase of mesoporous iron-titanium mixed oxide (ITMO) has been successfully synthesized by simple sol-gel technique by taking iron (II) sulphate and Ti-isopropoxide as the precursors and sodium dodecyl sulphate (SDS) as the surfactant. The prepared catalysts were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), diffuse reflectance UV-vis spectra (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic absorption spectroscopy (AAS), N2 adsorption-desorptions isotherm, temperature programmed desorption (TPD) and gas chromatography (GC). Low-angle XRD (LAXRD) as well as surface area analysis confirms the mesoporosity nature of the catalysts. The phase and crystallinity were revealed by XRD study. The crystallinity of the catalysts increased with increase in calcinations temperature. Catalysts screening were performed for oxidation of cyclohexane to cyclohexanol and cyclohexanone.

  15. Sol-gel synthesis and characterization of mesoporous iron-titanium mixed oxide for catalytic application

    Energy Technology Data Exchange (ETDEWEB)

    Parida, K.M., E-mail: paridakulamani@yahoo.com [Colloids and Materials Chemistry Department, Institute of Minerals and Materials Technology, Bhubaneswar 751013, Orissa (India); Pradhan, Gajendra Kumar [Colloids and Materials Chemistry Department, Institute of Minerals and Materials Technology, Bhubaneswar 751013, Orissa (India)

    2010-10-01

    A mixed phase of mesoporous iron-titanium mixed oxide (ITMO) has been successfully synthesized by simple sol-gel technique by taking iron (II) sulphate and Ti-isopropoxide as the precursors and sodium dodecyl sulphate (SDS) as the surfactant. The prepared catalysts were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), diffuse reflectance UV-vis spectra (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic absorption spectroscopy (AAS), N{sub 2} adsorption-desorptions isotherm, temperature programmed desorption (TPD) and gas chromatography (GC). Low-angle XRD (LAXRD) as well as surface area analysis confirms the mesoporosity nature of the catalysts. The phase and crystallinity were revealed by XRD study. The crystallinity of the catalysts increased with increase in calcinations temperature. Catalysts screening were performed for oxidation of cyclohexane to cyclohexanol and cyclohexanone.

  16. The decommissioning of large and complex glove box structures in a mixed oxide fuel fabrication plant

    International Nuclear Information System (INIS)

    Information is given concerning the different techniques applied during the decommissioning of glove boxes and equipment inside the BELGONUCLEAIRE Mixed Oxide fuel fabrication plant. The techniques have been selected on the basis of the glove box dimensions, the capability of being removed out of the building and/or being transported on the public road, the inner contamination level etc... Different techniques applied are explained. (author)

  17. The mechanism for free chlorine oxidation of reduced manganese in mixed-media filters

    OpenAIRE

    Occiano, Suzanne

    1988-01-01

    The removal mechanisms of soluble manganese [Mn (1l)] through mixed-media filters were investigated. Experimentation was directed toward the continuous supply of an oxidant during column filter studies. Free chlorine (HOCl, OC1â ) was chosen to increase soluble manganese removal efficiency because chlorine is readily available and inexpensive. Filter media from four different water treatment plants were used in this study. Continuous-flow filter columns were operated in the presence and a...

  18. Coordinated safeguards for materials management in a mixed-oxide fuel facility

    Energy Technology Data Exchange (ETDEWEB)

    Shipley, J.P.; Cobb, D.D.; Dietz, R.J.; Evans, M.L.; Schelonka, E.P.; Smith, D.B.; Walton, R.B.

    1977-02-01

    A coordinated safeguards system is described for safeguarding strategic quantities of special nuclear materials in mixed-oxide recycle fuel fabrication facilities. The safeguards system is compatible with industrial process requirements and combines maximum effectiveness consistent with modest cost and minimal process interference. It is based on unit process accounting using a combination of conventional and state-of-the-art NDA measurement techniques. The effectiveness of the system against single and multiple thefts is evaluated using computer modeling and simulation techniques.

  19. Experimental approach and atomistic simulations to investigate the radiation tolerance of complex oxides: Application to the amorphization of pyrochlores

    Science.gov (United States)

    Sattonnay, G.; Thomé, L.; Sellami, N.; Monnet, I.; Grygiel, C.; Legros, C.; Tetot, R.

    2014-05-01

    Both experimental approach and atomistic simulations are performed in order to investigate the influence of the composition of pyrochlores on their radiation tolerance. Therefore, Gd2Ti2O7 and Gd2Zr2O7 were irradiated with 4 MeV Au and 92 MeV Xe ions in order to study the structural changes induced by low and high-energy irradiations. XRD results show that, for both irradiations, the structural modifications are strongly dependent on the sample composition: Gd2Ti2O7 is readily amorphized, whereas Gd2Zr2O7 is transformed into a radiation-resistant anion-deficient fluorite structure. Using atomistic simulations with new interatomic potentials derived from the SMTB-Q model, the lattice properties and the defect formation energies were calculated in Gd2Ti2O7 and Gd2Zr2O7. Calculations show that titanates have a more covalent character than zirconates. Moreover, in Gd2Ti2O7 the formation of cation antisite defects leads to strong local distortions around Ti-defects and to a decrease of the Ti coordination number, which are not observed in Gd2Zr2O7. Thus, the radiation resistance is related to the defect stability: the accumulation of structural distortions around Ti-defects could drive the Gd2Ti2O7 amorphization induced by irradiation.

  20. Facile Routes To Improve Performance of Solution-Processed Amorphous Metal Oxide Thin Film Transistors by Water Vapor Annealing.

    Science.gov (United States)

    Park, Won-Tae; Son, Inyoung; Park, Hyun-Woo; Chung, Kwun-Bum; Xu, Yong; Lee, Taegweon; Noh, Yong-Young

    2015-06-24

    Here, we report on a simple and high-rate oxidization method for producing solution-based compound mixtures of indium zinc oxide (IZO) and indium gallium zinc oxide (IGZO) metal-oxide semiconductors (MOS) for thin-film transistor (TFT) applications. One of the issues for solution-based MOS fabrication is how to sufficiently oxidize the precursor in order to achieve high performance. As the oxidation rate of solution processing is lower than vacuum-based deposition such as sputtering, devices using solution-processed MOS exhibit relatively poorer performance. Therefore, we propose a method to prepare the metal-oxide precursor upon exposure to saturated water vapor in a closed volume for increasing the oxidization efficiency without requiring additional oxidizing agent. We found that the hydroxide rate of the MOS film exposed to water vapor is lower than when unexposed (≤18%). Hence, we successfully fabricated oxide TFTs with high electron mobility (27.9 cm(2)/V·s) and established a rapid process (annealing at 400 °C for 5 min) that is much shorter than the conventional as-deposited long-duration annealing (at 400 °C for 1 h) whose corresponding mobility is even lower (19.2 cm(2)/V·s). PMID:26043206

  1. Generic origin of subgap states in transparent amorphous semiconductor oxides illustrated for the cases of In-Zn-O and In-Sn-O

    Energy Technology Data Exchange (ETDEWEB)

    Koerner, Wolfgang; Urban, Daniel F.; Elsaesser, Christian [Fraunhofer Institute for Mechanics of Materials IWM, Woehlerstr. 11, 79108, Freiburg (Germany)

    2015-07-15

    We present a microscopic interpretation for the appearance and behaviour of subgap states in stoichiometric and oxygen-deficient, amorphous In-Zn-O (a-IZO) and In-Sn-O (a-ITO) derived from a density functional theory analysis using a self-interaction-correction scheme. Our findings concerning the defect structures and the resulting deep levels are qualitatively similar to earlier results on a-IGZO and a-ZTO and in agreement with recent experimental results. Based on our extensive set of DFT results for In-, Sn-, Zn- based oxides we develop a general concept of the subgap states which is applicable to these systems. Electronic defect levels in the lower half of the band gap are created by undercoordinated oxygen atoms while local oxygen deficiencies cause defect levels in the upper part of the band gap. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. A thermalization energy analysis of the threshold voltage shift in amorphous indium gallium zinc oxide thin film transistors under positive gate bias stress

    Science.gov (United States)

    Niang, K. M.; Barquinha, P. M. C.; Martins, R. F. P.; Cobb, B.; Powell, M. J.; Flewitt, A. J.

    2016-02-01

    Thin film transistors (TFTs) employing an amorphous indium gallium zinc oxide (a-IGZO) channel layer exhibit a positive shift in the threshold voltage under the application of positive gate bias stress (PBS). The time and temperature dependence of the threshold voltage shift was measured and analysed using the thermalization energy concept. The peak energy barrier to defect conversion is extracted to be 0.75 eV and the attempt-to-escape frequency is extracted to be 107 s-1. These values are in remarkable agreement with measurements in a-IGZO TFTs under negative gate bias illumination stress (NBIS) reported recently (Flewitt and Powell, J. Appl. Phys. 115, 134501 (2014)). This suggests that the same physical process is responsible for both PBS and NBIS, and supports the oxygen vacancy defect migration model that the authors have previously proposed.

  3. Scaling characteristics of depletion type, fully transparent amorphous indium-gallium-zinc-oxide thin-film transistors and inverters following Ar plasma treatment

    Science.gov (United States)

    Kim, Joonwoo; Jeong, Soon Moon; Jeong, Jaewook

    2015-11-01

    We fabricated depletion type, transparent amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) and inverters with an Ar plasma treatment and analyzed their scaling characteristics with channel lengths ranging from 2 to 100 µm. The improvement of the field-effect mobility of a-IGZO TFTs is apparent only for short channel lengths. There is also an unexpected side effect of the Ar plasma treatment, which introduces back-channel interfacial states and induces a positive shift in the threshold voltage of a-IGZO TFTs. The resulting increase in the field-effect mobility and the positive shift in the threshold voltage of each TFT increase the differential gain up to 3 times and the positive shift in the transient point of the transparent inverters.

  4. Methodologies For Characterising Mixed Conducting Oxides For Oxygen Membrane And SOFC Cathode Application

    DEFF Research Database (Denmark)

    Hendriksen, Peter Vang; Søgaard, Martin; Plonczak, Pawel

    2012-01-01

    Two methods for detailed characterization of the process of oxygen exchange between the gas phase and a mixed conducting solid oxide are discussed. First, the use of solid electrolyte probes for measuring the change in oxygen activity over the surface of a mixed conductor is presented and advanta......Two methods for detailed characterization of the process of oxygen exchange between the gas phase and a mixed conducting solid oxide are discussed. First, the use of solid electrolyte probes for measuring the change in oxygen activity over the surface of a mixed conductor is presented...... and advantages of the technique discussed. Secondly, the use of thin film model electrodes is treated. Studies of thin films applied by PLD on both sides of a YSZ single crystal are presented for three different film materials; La0.85Sr0.15MnO3, La0.6Sr0.4Fe0.8Co0.2O3 and La0.6Sr0.4CoO3. Variations in electrode...

  5. Catalytic combustion of soot over Ru-doped mixed oxides catalysts

    Institute of Scientific and Technical Information of China (English)

    LF Nascimento; RF Martins; OA Serra

    2014-01-01

    We employed modified substrates as outer heterogeneous catalysts to reduce the soot originating from the incomplete die-sel combustion. Here, we proposed that ceria (CeO2)-based catalysts could lower the temperature at which soot combustion occurred from 610 ºC to values included in the operation range of diesel exhausts (270-400 ºC). Here, we used the sol-gel method to synthesize catalysts based on mixed oxides (ZnO:CeO2) deposited on cordierite substrates, and modified by ruthenium nanoparticles. The presence of ZnO in these mixed oxides produced defects associated with oxygen vacancies, improving thermal stability, redox potential, sulfur resistance, and oxygen storage. We evaluated the morphological and structural properties of the material by X-ray diffraction (XRD), Brumauer-emmett-teller method (BET), temperature programmed reduction (H2-TPR), scanning electron micros-copy (SEM), and transmission electron microscopy (TEM). We investigated how the addition of Ru (0.5 wt.%) affected the catalytic activity of ZnO:CeO2 in terms of soot combustion. Thermogravimetric analysis (TG/DTA) revealed that presence of the catalyst de-creased the soot combustion temperature by 250 ºC, indicating that the oxygen species arose at low temperatures, which was the main reason for the high reactivity of the oxidation reactions. Comparative analysis of soot emission by diffuse reflectance spectroscopy (DRS) showed that the catalyst containing Ru on the mixed oxide-impregnated cordierite samples efficiently oxidized soot in a diesel stationary motor:soot emission decreased 80%.

  6. A 6b 10MS/s current-steering DAC manufactured with amorphous Gallium-Indium-Zinc-Oxide TFTs achieving SFDR > 30dB up to 300kHz

    NARCIS (Netherlands)

    Raiteri, D.; Torricelli, F.; Myny, K.; Nag, M.; Putten, B. van der; Smits, E.; Steudel, S.; Tempelaars, K.; Tripathi, A.K.; Gelinck, G.H.; Roermund, A. van; Cantatore, E.

    2012-01-01

    Amorphous Gallium-Indium-Zinc-Oxide (GIZO or IGZO) has been recently proposed [1] as an interesting semiconductor for manufacturing TFTs because of its mobility (μ∼20cm 2/Vs), superior to other common materials for large-area electronics like organic semiconductors and a-Si (μ∼1cm 2/Vs). The amorpho

  7. Catalysis of the rare earth containing mixed oxides Ln2CuO4 in phenol hydroxylation

    Institute of Scientific and Technical Information of China (English)

    刘持标; 赵震; 叶兴凯; 吴越

    1997-01-01

    Mixed oxides Ln2CuO4±λ(Ln=La,Pr,Nd,Sm,Gd) with K2NiF4 structure were prepared Their crystal structures were studied with XRD and IR spectra.Meanwhile,the average valence of Cu ions and non stoichiometric oxygen (λ) were determined through chemical analyses.Catalysis of the above-mentioned mixed oxides in the phenol hydroxylation was investigated.Results show that the catalysis of these mixed oxides has close relation with their structures and composition.Substitution of A site atom in Ln2CuO4λ has a great influence on then eatalysis in the phenol hydroxylation.

  8. Mixed

    Directory of Open Access Journals (Sweden)

    Pau Baya

    2011-05-01

    Full Text Available Remenat (Catalan (Mixed, "revoltillo" (Scrambled in Spanish, is a dish which, in Catalunya, consists of a beaten egg cooked with vegetables or other ingredients, normally prawns or asparagus. It is delicious. Scrambled refers to the action of mixing the beaten egg with other ingredients in a pan, normally using a wooden spoon Thought is frequently an amalgam of past ideas put through a spinner and rhythmically shaken around like a cocktail until a uniform and dense paste is made. This malleable product, rather like a cake mixture can be deformed pulling it out, rolling it around, adapting its shape to the commands of one’s hands or the tool which is being used on it. In the piece Mixed, the contortion of the wood seeks to reproduce the plasticity of this slow heavy movement. Each piece lays itself on the next piece consecutively like a tongue of incandescent lava slowly advancing but with unstoppable inertia.

  9. Improvement of bias-stability in amorphous-indium-gallium-zinc-oxide thin-film transistors by using solution-processed Y2O3 passivation

    International Nuclear Information System (INIS)

    We demonstrate back channel improvement of back-channel-etch amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors by using solution-processed yttrium oxide (Y2O3) passivation. Two different solvents, which are acetonitrile (35%) + ethylene glycol (65%), solvent A and deionized water, solvent B are investigated for the spin-on process of the Y2O3 passivation—performed after patterning source/drain (S/D) Mo electrodes by a conventional HNO3-based wet-etch process. Both solvents yield devices with good performance but those passivated by using solvent B exhibit better light and bias stability. Presence of yttrium at the a-IGZO back interface, where it occupies metal vacancy sites, is confirmed by X-ray photoelectron spectroscopy. The passivation effect of yttrium is more significant when solvent A is used because of the existence of more metal vacancies, given that the alcohol (65% ethylene glycol) in solvent A may dissolve the metal oxide (a-IGZO) through the formation of alkoxides and water

  10. Development of Stable Cerium Zirconium Mixed Oxide Nanoparticle Additive for Emission Reduction in Biodiesel Blends

    Directory of Open Access Journals (Sweden)

    Sajith V

    2015-06-01

    Full Text Available Harmful emissions associated with the use of biodiesel is a serious issue and various fuel additives are being used for the reduction of emissions as well as for the improvement of engine performance. Use of cerium oxide nanoparticles as fuel additive is one of the methods for the reduction of emissions, due to its peculiar redox functionality and oxygen buffering capability. Doping of ceria with transition metals such as zirconium improves its Oxygen storage capacity and thermal stability, thereby enhancing simultaneous oxidation and reduction reactions. The present work focuses on the development of cerium zirconium mixed oxide nanoparticle based additive for the reduction of emissions from diesel engine fuelled with biodiesel - diesel blends. Cerium zirconium mixed oxide was synthesized by means of co precipitation method. The stability of the nanofluids was improved by the addition of surfactant, namely Oleic acid. The optimum concentration of surfactant was determined based on estimation of critical micelle concentration, by means of standard tests. Stability of catalytic nanoparticle in fuel was evaluated from the measurement of Zeta potential. Various properties were determined as per ASTM standards to investigate the effect of the nanoparticles on fuel properties. Addition of catalytic nanoparticle in diesel - biodiesel blends does not significantly affect the fuel properties. Engine performance and emission tests were conducted on single cylinder diesel engine to assess the potential of synthesized nanofuel and 15% average reduction of NO emissions was observed for B5 and B10 blends with 15 ppm of catalytic nanoparticle concentration.

  11. Dry recovery test of plutonium-uranium mixed oxide fuel pellets

    International Nuclear Information System (INIS)

    The oxidation conditions for pulverizing directly Pu-U mixed oxide pellets without mechanical crushing were examined to simplify the process and to reduce radiation exposure during the dry recovery of highly enriched Pu pellets. The specimens used were the Pusub(0.3) Usub(0.7) Osub(2-x) pellets with different density, which were sintered at 1650 deg C for 2 hours under an atmosphere of 5 % H2 - N2. The oxidation experiment was carried out under several conditions. The oxidation products were examined by weight gain, X-ray diffraction, appearance pictures, SEM photographs and so on. From these studies, it can be concluded that the oxidation in NO2 diluted with air was very powerful, but if only the coarse spalling of Pusub(0.3) Usub(0.7) O2 sintered pellets is required, it is sufficient to oxidize them in air for 1 hr in a temperature range from 400 to 600 deg C. (Asami, T.)

  12. Late-occurring pulmonary pathologies following inhalation of mixed oxide (uranium + plutonium oxide) aerosol in the rat.

    Science.gov (United States)

    Griffiths, N M; Van der Meeren, A; Fritsch, P; Abram, M-C; Bernaudin, J-F; Poncy, J L

    2010-09-01

    Accidental exposure by inhalation to alpha-emitting particles from mixed oxide (MOX: uranium and plutonium oxide) fuels is a potential long-term health risk to workers in nuclear fuel fabrication plants. For MOX fuels, the risk of lung cancer development may be different from that assigned to individual components (plutonium, uranium) given different physico-chemical characteristics. The objective of this study was to investigate late effects in rat lungs following inhalation of MOX aerosols of similar particle size containing 2.5 or 7.1% plutonium. Conscious rats were exposed to MOX aerosols and kept for their entire lifespan. Different initial lung burdens (ILBs) were obtained using different amounts of MOX. Lung total alpha activity was determined by external counting and at autopsy for total lung dose calculation. Fixed lung tissue was used for anatomopathological, autoradiographical, and immunohistochemical analyses. Inhalation of MOX at ILBs ranging from 1-20 kBq resulted in lung pathologies (90% of rats) including fibrosis (70%) and malignant lung tumors (45%). High ILBs (4-20 kBq) resulted in reduced survival time (N = 102; p plutonium oxide alone (1.9% Gy). Staining with antibodies against Surfactant Protein-C, Thyroid Transcription Factor-1, or Oct-4 showed differential labeling of tumor types. In conclusion, late effects following MOX inhalation result in similar risk for development of lung tumors as compared with industrial plutonium oxide.

  13. Preparation of catalysts based on Ce-Mn mixed oxide by coprecipitation for combustion of n-hexane

    International Nuclear Information System (INIS)

    Catalysts based on Ce-Mn mixed with different Ce/Mn molar ratios ranging from 0,5 to 2 have been prepared by coprecipitation at pH constant with ageing times of 4, 18 and 24 h for combustion of n-hexane. XRD patterns of the mixed oxides showed the majority presence of fluorite phase. Specific BET surface areas of mixed oxides were always higher than their single counterparts and their adsorption isotherm depicted a mesoporous surface of Type IV. TPR thermograms confirmed the presence of mixed oxide phase, whose profile shifted to smaller temperatures with increasing content of ceria. Catalytic tests were performed with 2000 ppm of n-hexane and WHSV of 80 h-1 in a fixed-bed reactor. For all samples, only CO2 and water were observed at total conversion and no partial combustion products were obtained. Ce-Mn mixed oxides were more active than simple oxide samples no matter the aging time. Mixed samples presented thermal stability in contrast with simple ones. Mixed sample with Ce/Mn molar ratio of 2 depicted the highest activity probably due to higher surface area and better reducibility ability of mixed phase. (author)

  14. The mechanism of oxygen reactions at porous oxide electrodes Part III: Water oxidation catalysis at RuO2/NiO mixed oxide electrodes

    OpenAIRE

    Lyons, Michael

    2014-01-01

    RuO2/NiO mixed oxide electrodes prepared by thermal decomposition were examined as potential water oxidation catalysts. Addition of just 10 mol% RuO2 to a NiO electrode was found to decrease the oxygen evolution reaction (OER) onset potential by 20% with increasing additions having significantly diminishing returns. The OER current densities for the RuO2/NiO electrode were found to increase when preconditioned by application of prolonged polarization regimes with the Tafel slope also decreasi...

  15. Surface composition and catalytic activity of La-Fe mixed oxides for methane oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fengxiang [School of Chemistry, Beijing Institute of Technology, Liangxiang East Road, Beijing 102488 (China); Li, Zhanping [Analysis Center, Tsinghua University, Beijing 100084 (China); Ma, Hongwei [School of Chemistry, Beijing Institute of Technology, Liangxiang East Road, Beijing 102488 (China); Gao, Zhiming, E-mail: zgao@bit.edu.cn [School of Chemistry, Beijing Institute of Technology, Liangxiang East Road, Beijing 102488 (China)

    2015-10-01

    Graphical abstract: - Highlights: • The sample with La/Fe atomic ratio of 0.94 is single phase perovskite La{sub 0.94}FeO{sub 3−d}. • The excess ironic oxide exists on the surface of the perovskite crystallites. • La{sup 3+} ions are enriched on surface of the oxides even for the La{sub 0.68}Fe sample. - Abstract: Four La-Fe oxide samples with La/Fe atomic ratio y = 1.02 ∼ 0.68 (denoted as LayFe) were prepared by the citrate method. The samples had a decreased specific surface area with the La/Fe atomic ratio decreasing. XRD pattern proved that the sample La{sub 0.94}Fe is single phase perovskite La{sub 0.94}FeO{sub 3−d}. Phase composition of the samples was estimated by the Rietveld refinement method. XPS analyses indicate that La{sup 3+} ions are enriched on surface of crystallites for all the samples, and surface carbonate ions are relatively abundant on the samples La{sub 1.02}Fe and La{sub 0.94}Fe. Catalytic activity for methane oxidation per unit surface area of the samples is in the order of La{sub 0.68}Fe > La{sub 0.76}Fe > La{sub 0.94}Fe > La{sub 1.02}Fe both in the presence and in the absence of gaseous oxygen. A reason for this order would be the higher concentration of Fe{sup 3+} ion on the surface of the samples La{sub 0.68}Fe and La{sub 0.76}Fe.

  16. Oxidative potential of smoke from burning wood and mixed biomass fuels.

    Science.gov (United States)

    Kurmi, O P; Dunster, C; Ayres, J G; Kelly, F J

    2013-10-01

    More than half the world's population still rely on burning biomass fuels to heat and light their homes and cook food. Household air pollution, a common component of which is inhalable particulate matter (PM), emitted from biomass burning is associated with increased vulnerability to respiratory infection and an enhanced risk of developing chronic obstructive pulmonary disease. In the light of an emerging hypothesis linking chronic PM exposure during childhood and increased vulnerability to respiratory diseases in adulthood, in a chain of events involving oxidative stress, reduced immunity and subsequent infection, the aim of this study was to characterise the oxidative potential (OP) of PM collected during the burning of wood and mixed biomass, whilst cooking food in the Kathmandu Valley, Nepal. Our assessments were based on the capacity of the particles to deplete the physiologically relevant antioxidants from a validated, synthetic respiratory tract lining fluid (RTLF). Incubation of mixed biomass and wood smoke particles suspensions with the synthetic RTLF for 4 h resulted in a mean loss of ascorbate of 64.76 ± 16.83% and 83.37 ± 14.12% at 50 μg/ml, respectively. Reduced glutathione was depleted by 49.29 ± 15.22% in mixed biomass and 65.33 ± 13.01% in wood smoke particles under the same conditions. Co-incubation with the transition metal chelator diethylenetriaminepentaacetate did not inhibit the rate of ascorbate oxidation, indicating a negligible contribution by redox-active metals in these samples. The capacity of biomass smoke particles to elicit oxidative stress certainly has the potential to contribute towards negative health impacts associated with traditional domestic fuels in the developing world. PMID:23926954

  17. Nano-vanadium oxide thin films in mixed phase for microbolometer applications

    Energy Technology Data Exchange (ETDEWEB)

    Subrahmanyam, A; Bharat Kumar Reddy, Y [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Nagendra, C L [LEOS, ISRO, Peenya Industrial Estate, Bangalore 560060 (India)], E-mail: manu@iitm.ac.in

    2008-10-07

    Among the several phases of vanadium oxide, mixed phases of VO{sub 2} and V{sub 2}O{sub 5} are preferred for uncooled micro-bolometers with low noise. The aim of this investigation is to achieve mixed phase VO{sub 2} and V{sub 2}O{sub 5} thin films with nanometre grain sizes and high temperature coefficient of resistance (TCR). Since the phase depends upon the oxygen reactivity, these vanadium oxide thin films are prepared by reactive electron beam evaporation at different oxygen flow rates and substrate temperatures. The mixed phases have been evaluated through x-ray diffraction and x-ray photo emission studies. The temperature dependence of resistance has shown that the films grown at 473 K with 2.8 x 10{sup -5} mbar chamber pressure of oxygen (VO{sub 2} : V{sub 2}O{sub 5} ratio of 36 : 64) have the highest TCR of -3.2 K{sup -1} with a reasonable low resistance (120 {omega}/square)

  18. Poisoning and reactivation processes in oxide-type cathodes: Part I. Polycrystalline mixed oxides

    Science.gov (United States)

    Shih, A.; Haas, G. A.

    A study has been made of the poisoning and reactivation characteristics of alkaline earth oxide-type cathodes after extended periods of shelf storage. Both emitted and incident electrons were used to measure changes in the electronics properties, i.e. work function. The variations in work function over the surface were obtained in both distribution form as well as topographic presentation using a scanning low energy electron probe (SLEEP). These measurements were correlated with simultaneously occurring compositional changes using Auger, gas desorption and ion scattering techniques. Measurements were made on realistic cathodes in actual vacuum tube ambients. The results showed that oxide-type cathodes poison within a few hours after shut-down by the adsorption of residual gases contained in the vacuum ambient. (The effects of CO 2 were specifically demonstrated.) These adsorbates are, however, desorbed upon heating and in combination with other reactivation processes (such as formation of surface Ba layers when using reducing substrates), the cathode can reach full activation again by the time the temperature reaches the normal operating temperature. The poisoning and reactivation phenomena are a combination of a number of simultaneous processes, and studies to separate and identify these is the objective of part II of this paper.

  19. Influence of Gold on Ce-Zr-Co Fluorite-Type Mixed Oxide Catalysts for Ethanol Steam Reforming

    Directory of Open Access Journals (Sweden)

    Véronique Pitchon

    2012-02-01

    Full Text Available The effect of gold presence on carbon monoxide oxidation and ethanol steam reforming catalytic behavior of two Ce-Zr-Co mixed oxides catalysts with a constant Co charge and different Ce/Zr ratios was investigated. The Ce-Zr-Co mixed oxides were obtained by the pseudo sol-gel like method, based on metallic propionates polymerization and thermal decomposition, whereas the gold-supported Ce-Zr-Co mixed oxides catalysts were prepared using the direct anionic exchange. The catalysts were characterized using XRD, TPR, and EDXS-TEM. The presence of Au in doped Ce-Zr-Co oxide catalyst decreases the temperature necessary to reduce the cobalt and the cerium loaded in the catalyst and favors a different reaction pathway, improving the acetaldehyde route by ethanol dehydrogenation, instead of the ethylene route by ethanol dehydration or methane re-adsorption, thus increasing the catalytic activity and selectivity into hydrogen.

  20. Characterizing Amorphous Silicates in Extraterrestrial Materials

    Science.gov (United States)

    Fu, X.; Wang, A.; Krawczynski, M. J.

    2015-12-01

    Amorphous silicates are common in extraterrestrial materials. They are seen in the matrix of carbonaceous chondrites as well as in planetary materials. Tagish Lake is one of the most primitive carbonaceous meteorites in which TEM and XRD analyses found evidence for poorly crystalline phyllosilicate-like species; Raman spectra revealed amorphous silicates with variable degree of polymerization and low crystallinity. On Mars, CheMin discovered amorphous phases in all analyzed samples, and poorly crystalline smectite in mudstone samples. These discoveries pose questions on the crystallinity of phyllosilicates found by remote sensing on Mars, which is directly relevant to aqueous alteration during geologic history of Mars. Our goal is to use spectroscopy to better characterize amorphous silicates. We use three approaches: (1) using silicate glasses synthesized with controlled chemistry to study the effects of silicate polymerization and (2) using phyllosilicates synthesized with controlled hydrothermal treatment to study the effect of crystallinity on vibrational spectroscopy, finally (3) to use the developed correlations in above two steps to study amorphous phases in meteorites, and those found in future missions to Mars. In the 1st step, silicate glasses were synthesized from pure oxides in a range of NBO/T ratios (from 0 to 4). Depending on the targeted NBO/T and composition of mixed oxides, temperatures for each experiment fell in a range from 1260 to 1520 °C, run for ~ 4 hrs. The melt was quenched in liquid N2 or water. Homogeneity of glass was checked under optical microscopy. Raman spectra were taken over 100 spots on small chips free of bubbles and crystals. We have observed that accompanying an increase of NBO/T, there is a strengthening and a position shift of the Raman peak near 1000 cm-1 (Si-Onon-bridging stretching mode), and the weakening of broad Raman peaks near 500 cm-1 (ring breathing mode) and 700cm-1 (Si-Obridging-Si mode). We are building the

  1. Feasibility Study of 1/3 Thorium-Plutonium Mixed Oxide Core

    Directory of Open Access Journals (Sweden)

    Cheuk Wah Lau

    2014-01-01

    Full Text Available Thorium-plutonium mixed oxide (Th-MOX fuel has become one of the most promising solutions to reduce a large and increasing plutonium stockpile. Compared with traditional uranium-plutonium mixed oxide (U-MOX fuels, Th-MOX fuel has higher consumption rate of plutonium in LWRs. Besides, thorium based fuels have improved thermomechanical material properties compared with traditional U-MOX fuels. Previous studies on a full Th-MOX core have shown reduced efficiency in reactivity control mechanisms, stronger reactivity feedback, and a significantly lower fraction of delayed neutrons compared with a traditional uranium oxide (UOX core. These problems complicate the implementation of a full Th-MOX core in a similar way as for a traditional U-MOX core. In order to reduce and avoid some of these issues, the introduction of a lower fraction of Th-MOX fuel in the core is proposed. In this study, one-third of the assemblies are Th-MOX fuel, and the rest are traditional UOX fuel. The feasibility study is based on the Swedish Ringhals-3 PWR. The results show that the core characteristics are more similar to a traditional UOX core, and the fraction of delayed neutrons is within acceptable limits. Moreover, the damping of axial xenon oscillations induced by control rod insertions is almost 5 times more effective for the 1/3 Th-MOX core compared with the standard core.

  2. Resonant structures based on amorphous silicon sub-oxide doped with Er3+ with silicon nanoclusters for an efficient emission at 1550 nm

    CERN Document Server

    Figueira, D S L; Tessler, L R; Frateschi, N C

    2009-01-01

    We present a resonant approach to enhance 1550nm emission efficiency of amorphous silicon sub-oxide doped with Er3+ (a-SiOx) layers with silicon nanoclusters (Si-NC). Two distinct techniques were combined to provide a structure that allowed increasing approximately 12x the 1550nm emission. First, layers of SiO2 were obtained by conventional wet oxidation and a-SiOx matrix was deposited by reactive RF co-sputtering. Secondly, an extra pump channel (4I15/2 to 4I9/2) of Er3+ was created due to Si-NC formation on the same a-SiOx matrix via a hard annealing at 1150 C. The SiO2 and the a-SiOx thicknesses were designed to support resonances near the pumping wavelength (~500nm), near the Si-NC emission (~800nm) and near the a-SiOx emission (~1550nm) enhancing the optical pumping process.

  3. A transparent diode with high rectifying ratio using amorphous indium-gallium-zinc oxide/SiN{sub x} coupled junction

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Myung-Jea; Kim, Myeong-Ho; Choi, Duck-Kyun, E-mail: duck@hanyang.ac.kr [Department of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2015-08-03

    We introduce a transparent diode that shows both high rectifying ratio and low leakage current at process temperature below 250 °C. This device is clearly distinguished from all previous transparent diodes in that the rectifying behavior results from the junction between a semiconductor (amorphous indium-gallium-zinc oxide (a-IGZO)) and insulator (SiN{sub x}). We systematically study the properties of each junction within the device structure and demonstrate that the a-IGZO/SiN{sub x} junction is the source of the outstanding rectification. The electrical characteristics of this transparent diode are: 2.8 A/cm{sup 2} on-current density measured at −7 V; lower than 7.3 × 10{sup −9} A/cm{sup 2} off-current density; 2.53 ideality factor; and high rectifying ratio of 10{sup 8}–10{sup 9}. Furthermore, the diode structure has a transmittance of over 80% across the visible light range. The operating principle of the indium-tin oxide (ITO)/a-IGZO/SiN{sub x}/ITO device was examined with an aid of the energy band diagram and we propose a preliminary model for the rectifying behavior. Finally, we suggest further directions for research on this transparent diode.

  4. Influence of molybdenum source/drain electrode contact resistance in amorphous zinc–tin-oxide (a-ZTO) thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Han, Dong-Suk; Kang, Yu-Jin; Park, Jae-Hyung [Department of Nanoscale Semiconductor Engineering, Hanyang University, 17 Haengdang-dong, Seoungdong-ku, Seoul 133-791 (Korea, Republic of); Jeon, Hyung-Tag [Department of Materials Science and Engineering, Hanyang University, 17 Haengdang-dong, Seoungdong-ku, Seoul 133-791 (Korea, Republic of); Park, Jong-Wan, E-mail: jwpark@hanyang.ac.kr [Department of Materials Science and Engineering, Hanyang University, 17 Haengdang-dong, Seoungdong-ku, Seoul 133-791 (Korea, Republic of)

    2014-10-15

    Highlights: • We developed and investigated source/drain electrodes in oxide TFTs. • The Mo S/D electrodes showed good output characteristics. • Intrinsic TFT parameters were calculated by the transmission line method. - Abstract: This paper investigates the feasibility of a low-resistivity electrode material (Mo) for source/drain (S/D) electrodes in thin film transistors (TFTs). The effective resistances between Mo source/drain electrodes and amorphous zinc–tin-oxide (a-ZTO) thin film transistors were studied. Intrinsic TFT parameters were calculated by the transmission line method (TLM) using a series of TFTs with different channel lengths measured at a low source/drain voltage. The TFTs fabricated with Mo source/drain electrodes showed good transfer characteristics with a field-effect mobility of 10.23 cm{sup 2}/V s. In spite of slight current crowding effects, the Mo source/drain electrodes showed good output characteristics with a steep rise in the low drain-to-source voltage (V{sub DS}) region.

  5. High-pressure Gas Activation for Amorphous Indium-Gallium-Zinc-Oxide Thin-Film Transistors at 100 °C

    Science.gov (United States)

    Kim, Won-Gi; Tak, Young Jun; Du Ahn, Byung; Jung, Tae Soo; Chung, Kwun-Bum; Kim, Hyun Jae

    2016-03-01

    We investigated the use of high-pressure gases as an activation energy source for amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistors (TFTs). High-pressure annealing (HPA) in nitrogen (N2) and oxygen (O2) gases was applied to activate a-IGZO TFTs at 100 °C at pressures in the range from 0.5 to 4 MPa. Activation of the a-IGZO TFTs during HPA is attributed to the effect of the high-pressure environment, so that the activation energy is supplied from the kinetic energy of the gas molecules. We reduced the activation temperature from 300 °C to 100 °C via the use of HPA. The electrical characteristics of a-IGZO TFTs annealed in O2 at 2 MPa were superior to those annealed in N2 at 4 MPa, despite the lower pressure. For O2 HPA under 2 MPa at 100 °C, the field effect mobility and the threshold voltage shift under positive bias stress were improved by 9.00 to 10.58 cm2/V.s and 3.89 to 2.64 V, respectively. This is attributed to not only the effects of the pressurizing effect but also the metal-oxide construction effect which assists to facilitate the formation of channel layer and reduces oxygen vacancies, served as electron trap sites.

  6. Large scale integration of flexible non-volatile, re-addressable memories using P(VDF-TrFE) and amorphous oxide transistors

    International Nuclear Information System (INIS)

    Ferroelectric polymers and amorphous metal oxide semiconductors have emerged as important materials for re-programmable non-volatile memories and high-performance, flexible thin-film transistors, respectively. However, realizing sophisticated transistor memory arrays has proven to be a challenge, and demonstrating reliable writing to and reading from such a large scale memory has thus far not been demonstrated. Here, we report an integration of ferroelectric, P(VDF-TrFE), transistor memory arrays with thin-film circuitry that can address each individual memory element in that array. n-type indium gallium zinc oxide is used as the active channel material in both the memory and logic thin-film transistors. The maximum process temperature is 200 °C, allowing plastic films to be used as substrate material. The technology was scaled up to 150 mm wafer size, and offers good reproducibility, high device yield and low device variation. This forms the basis for successful demonstration of memory arrays, read and write circuitry, and the integration of these. (paper)

  7. Voltammetric Studies of Propranolol and Hydrochlorothiazide Oxidation in Standard and Synthetic Biological Fluids Using a Nitrogen-Containing Tetrahedral Amorphous Carbon (ta-C:N) Electrode

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Nitrogen-containing tetrahedral amorphous carbon electrode for electroanalysis. • Electrochemical behavior of propranolol (PROP) and hydrochlorothiazide (HTZ). • ta-C:N electrode presents good electrochemical performance for PROP and HTZ. • Electrochemical performance of ta-C:N electrode is similar to the BDD electrode. • PROP and HTZ are simultaneously quantified in artificial biological samples. - Abstract: The electrochemical detection of two pharmaceuticals, propranolol (PROP) and hydrochlorothiazide (HTZ), was studied using a nitrogen-containing tetrahedral amorphous carbon (ta-C:N) electrode. Measurements were also made using a boron-doped diamond (BDD) electrode, for comparison. The ta-C:N electrode functioned well for the simultaneous determination of PROP and HTZ in artificial urine and serum by square-wave voltammetry, both of which were detected at high positive potentials. The PROP (ca. 1.2 V) and HTZ (ca. 1.4 V) oxidation peak potentials were separated by about 200 mV. The respective analytical response curves presented good linearity in the investigated concentration range from 0.9 to 9.8 μmol L−1 for PROP and from 3.0 to 9.8 μmol L−1 for HTZ with calculated limits of detection (S/N = 3) of 0.75 μmol L−1 (∼194 ng/mL) for PROP and 2.50 μmol L−1 (∼744 ng/mL) for HTZ. Essentially, the lowest concentration measured voltammetrically was the LOD. The results indicate that the ta-C:N electrode could be an excellent new carbon material for electrochemically-active analytes requiring high potentials for detection

  8. Engineering development and demonstration of DETOXSM wet oxidation for mixed waste treatment

    International Nuclear Information System (INIS)

    DETOXSM, a catalyzed chemical oxidation process, is under development for treatment of hazardous and mixed wastes at Department of Energy sites. To support this effort, developmental engineering studies have been formed for aspects of the process to help ensure safe and effective operation. Subscale agitation studies have been preformed to identify a suitable mixing head and speed for the primary reaction vessel agitator. Mechanisms for feeding solid waste materials to the primary reaction vessel have been investigated. Filtration to remove solid field process residue, and the use of various filtration aids, has been studied. Extended compatibility studies on the materials of construction have been performed. Due to a change to Rocky Flats Environmental Technology Site (RFETS) for the mixed waste portion of the demonstration, types of wastes suitable and appropriate for treatment at RFETS had to be chosen. A Prototype unit has been fabricated and will be demonstrated on hazardous and mixed wastes at Savannah River Site (SRS) and RFETS during 1997 and 1998. The unit is in shakedown testing at present. Data validation and an engineering evaluation will be performed during the demonstration

  9. Neutronics benchmark for the Quad Cities-1 (Cycle 2) mixed oxide assembly irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, S.E.; Difilippo, F.C.

    1998-04-01

    Reactor physics computer programs are important tools that will be used to estimate mixed oxide fuel (MOX) physics performance in support of weapons grade plutonium disposition in US and Russian Federation reactors. Many of the computer programs used today have not undergone calculational comparisons to measured data obtained during reactor operation. Pin power, the buildup of transuranics, and depletion of gadolinium measurements were conducted (under Electric Power Research Institute sponsorship) on uranium and MOX pins irradiated in the Quad Cities-1 reactor in the 1970`s. These measurements are compared to modern computational models for the HELIOS and SCALE computer codes. Good agreement on pin powers was obtained for both MOX and uranium pins. The agreement between measured and calculated values of transuranic isotopes was mixed, depending on the particular isotope.

  10. Effect of the preparation method on the physicochemical properties of mixed magnesium-vanadium oxides

    International Nuclear Information System (INIS)

    Mixed Mg-V oxides have been prepared following three different methods (calcination of precursors constituted by a layered double hydroxide, impregnation of MgO with vanadate, or mechanical MgO-V2O5 mixtures), and have been characterized following powder X-ray diffraction, X-ray absorption spectroscopy, vis-UV and FT-IR spectroscopies, thermal analysis, temperature-programmed reduction, and specific surface area assessment. Mg3V2O8 is mainly formed, although small amounts of α-Mg2V2O7 are detected in some cases, in addition to MgO

  11. Oxygen storage and catalytic NO removal promoted by CeO2-containing mixed oxides

    International Nuclear Information System (INIS)

    CeO2-ZrO2 mixed oxides show improved redox properties as compared to CeO2 which makes them important innovative materials for three-way catalysts. The origin of this effect and the structural/redox correlation are discussed. The influence of the improved redox capacities on the reduction of NO by CO catalyzed by Rh/CeO2-ZrO2 catalysts is reported and evidence for an active role of the CeO2-ZrO2 support in NO activation is presented. (orig.)

  12. Detailed description of an SSAC at the facility level for mixed oxide fuel fabrication facilities

    International Nuclear Information System (INIS)

    The purpose of this document is to provide a detailed description of a system for the accounting for and control of nuclear material in a mixed oxide fuel fabrication facility which can be used by a facility operator to establish his own system to comply with a national system for nuclear material accounting and control and to facilitate application of IAEA safeguards. The scope of this document is limited to descriptions of the following SSAC elements: (1) Nuclear Material Measurements; (2) Measurement Quality; (3) Records and Reports; (4) Physical Inventory Taking; (5) Material Balance Closing

  13. Tunable catalytic properties of bi-functional mixed oxides in ethanol conversion to high value compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Karthikeyan K.; Gray, Michel J.; Job, Heather M.; Smith, Colin D.; Wang, Yong

    2016-04-10

    tA highly versatile ethanol conversion process to selectively generate high value compounds is pre-sented here. By changing the reaction temperature, ethanol can be selectively converted to >C2alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3cata-lyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensationor the acetone formation is the path taken in changing the product composition. This article containsthe catalytic activity comparison between the mono-functional and physical mixture counterpart to thehydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

  14. Mg-Fe-mixed oxides derived from layered double hydroxides: A study of the surface properties

    OpenAIRE

    Marinković-Nedučin Radmila P.; Nikolić Aleksandar D.; Jović Branislav; Hadnađev-Kostić Milica S.; Vulić Tatjana J.

    2011-01-01

    The influence of surface properties on the selectivity of the synthesized catalysts was studied, considering that their selectivity towards particular hydrocarbons is crucial for their overall activity in the chosen Fischer- -Tropsch reaction. Magnesium- and iron-containing layered double hydroxides (LDH), with the general formula: [Mg1-xFex(OH)2](CO3)x/2?mH2O, x = = n(Fe)/(n(Mg)+n(Fe)), synthesized with different Mg/Fe ratio and their thermally derived mixed oxides were investigated. M...

  15. Glycerol oxidehydration to acrylic acid on complex mixed-metal oxides

    OpenAIRE

    Chieregato, Alessandro

    2015-01-01

    [EN] The project of this Ph.D. thesis is based on a co-supervised collaboration between Università di Bologna, ALMA MATER STUDIORUM (Italy) and Instituto de Tecnología Química, Universitat Politècnica de València ITQ-UPV (Spain). This Ph.D. thesis is about the synthesis, characterization and catalytic testing of complex mixed-oxide catalysts mainly related to the family of Hexagonal Tungsten Bronzes (HTBs). These materials have been little explored as catalysts, although they have a great...

  16. Influence of oxidation temperature on photoluminescence and electrical properties of amorphous thin film SiC:H:O+Tb

    Energy Technology Data Exchange (ETDEWEB)

    Gordienko, S.O.; Nazarov, A.N.; Rusavsky, A.V.; Vasin, A.V.; Gomeniuk, Yu.V.; Lysenko, V.S.; Strelchuk, V.V.; Nikolaenko, A.S. [Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Prospekt Nauki 41, 03028 Kyiv (Ukraine); Ashok, S. [The Pennsylvania State University, Department of Engineering Science, 212 Earth and Engineering Science Bldg., University Park, PA 16802 (United States)

    2011-09-15

    The influence of low-temperature oxidation on chemical composition, luminescent and electrical properties of a-Si{sub 1-x}C{sub x}:H thin films fabricated by reactive RF magnetron sputtering has been studied. A strong dependence on RF sputtering power is seen on the electrical and chemical properties. The a-Si{sub 1-x}C{sub x}:H films fabricated by low RF power levels followed by low-temperature oxidation (at 450 C-500 C) display high intensity of PL, good MOSCV characteristic and low leakage current through the dielectric. Increase of oxidation temperature increases precipitation of carbon nano-inclusions in the materials, that result in reduction of PL intensity and increase of dielectric leakage. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. PREPARATION AND PROPERTIES OF Co-Fe MIXED OXIDES OBTAINED BY CALCINATION OF LAYERED DOUBLE HYDROXIDES

    Directory of Open Access Journals (Sweden)

    M. E. Pérez Bernal

    2004-12-01

    Full Text Available Solids containing Co(II and Fe(III with molar ratios of 2/1, 3/2, 1/1, 2/3 and 1/2 have been synthetised by coprecipitation at constant pH. All they displayed a hydrotalcite-like structure with interlayer carbonate, which crystallinity decreases as the iron content was increased. No other crystalline phase was identified, even in the Fe-rich samples. They have been characterised by powder X-ray diffraction, FT-IR spectroscopy, thermal analysis (differential thermal analysis, thermogravimetric analysis and temperature-programmed reduction, in addition to specific surface area assessment by nitrogen adsorption at -196°C. A minor oxidation of Co(II to Co(III is observed in the Co-rich samples, although it reverses again to Co(II upon calcination in oxygen at ca. 850°C. Thermal decomposition takes place in a single step up to ca. 350°C, and the specific surface area increases with the iron content, probably because of the presence of hydrated amorphous iron oxides. The solids calcined at 1200°C in air contain crystalline CoO, Co3O4 and CoFe2O4 (spinel, this one being the dominant phase, and only phase detected for large Fe contents. Metallic species are more easily reduced in the original solids than in the calcined ones, and in all cases iron seems to be reduced at a higher temperature than cobalt.

  18. Characterization of plutonium aerosols from an industrial mixed-oxide fuel fabrication facility

    International Nuclear Information System (INIS)

    Samples of the aerosols present in a glove box during a plutonium oxide and uranium oxide powder mixing operation were taken with a small seven-stage cascade impactor to determine the aerodynamic size distribution and concentration and with a Lovelace Aerosol Particle Separator (LAPS) to study the characteristics of the particles with respect to aerodynamic equivalent size. Using alpha spectroscopy, it was found that about 11 percent of the alpha activity of the aerosol was associated with 241Am. The size distributions measured with the cascade impactor had activity median aerodynamic diameters (AMAD) equal to 1.9 +- 0.3 (S.D.) μm and geometric standard deviations (sigma/sub g/) equal to 1.59 +- 0.07 with alpha activity concentrations best expressed as log-normally distributed with median of 45 nCi/l and geometric standard deviation of 1.8. (U.S.)

  19. Application of a mixed metal oxide catalyst to a metallic substrate

    Science.gov (United States)

    Sevener, Kathleen M. (Inventor); Lohner, Kevin A. (Inventor); Mays, Jeffrey A. (Inventor); Wisner, Daniel L. (Inventor)

    2009-01-01

    A method for applying a mixed metal oxide catalyst to a metallic substrate for the creation of a robust, high temperature catalyst system for use in decomposing propellants, particularly hydrogen peroxide propellants, for use in propulsion systems. The method begins by forming a prepared substrate material consisting of a metallic inner substrate and a bound layer of a noble metal intermediate. Alternatively, a bound ceramic coating, or frit, may be introduced between the metallic inner substrate and noble metal intermediate when the metallic substrate is oxidation resistant. A high-activity catalyst slurry is applied to the surface of the prepared substrate and dried to remove the organic solvent. The catalyst layer is then heat treated to bind the catalyst layer to the surface. The bound catalyst layer is then activated using an activation treatment and calcinations to form the high-activity catalyst system.

  20. Microstructural Modeling of Thermal Conductivity of High Burn-up Mixed Oxide Fuel

    International Nuclear Information System (INIS)

    Predicting the thermal conductivity of oxide fuels as a function of burn-up and temperature is fundamental to the efficient and safe operation of nuclear reactors. However, modeling the thermal conductivity of fuel is greatly complicated by the radially inhomogeneous nature of irradiated fuel in both composition and microstructure. In this work, radially and temperature-dependent models for effective thermal conductivity were developed utilizing optical micrographs of high burn-up mixed oxide fuel. The micrographs were employed to create finite element meshes with the OOF2 software. The meshes were then used to calculate the effective thermal conductivity of the microstructures using the BISON fuel performance code. The new thermal conductivity models were used to calculate thermal profiles at end of life for the fuel pellets. These results were compared to thermal conductivity models from the literature, and comparison between the new finite element-based thermal conductivity model and the Duriez-Lucuta model was favorable

  1. Fabrication of Nb{sub 2}O{sub 5}/SiO{sub 2} mixed oxides by reactive magnetron co-sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Juškevičius, Kęstutis, E-mail: kestutis.juskevicius@ftmc.lt [Center for Physical Sciences and Technology, Savanorių ave. 231, LT-02300 Vilnius (Lithuania); Audronis, Martynas, E-mail: m.audronis@yahoo.co.uk [Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin street, S1 3JD (United Kingdom); Subačius, Andrius; Kičas, Simonas; Tolenis, Tomas; Buzelis, Rytis; Drazdys, Ramutis; Gaspariūnas, Mindaugas; Kovalevskij, Vitalij [Center for Physical Sciences and Technology, Savanorių ave. 231, LT-02300 Vilnius (Lithuania); Matthews, Allan; Leyland, Adrian [Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin street, S1 3JD (United Kingdom)

    2015-08-31

    This paper investigates niobia/silica mixed oxide thin films deposited by reactive pulse-DC/RF magnetron co-sputtering of Nb and Si metal targets at room temperature. The reactive gas flow during the sputtering processes was either controlled by direct mass flow rate (i.e. constant reactive gas flow) or by an active feedback process control system. 61% and 137% higher deposition rates of Nb{sub 2}O{sub 5} and SiO{sub 2} layers, respectively, were obtained using the latter technique as compared to constant reactive gas flow. Films exhibited bulk or near-bulk density. All mixture films produced in this study had an amorphous structure. A volume law of mixtures was used to determine the coating composition. It is shown that the fraction of SiO{sub 2} or/and Nb{sub 2}O{sub 5} has a linear dependency on sputter target power density. On this basis, rugate filter coating designs can be easily deposited, where refractive index gradually varies between that of pure Nb{sub 2}O{sub 5} and pure SiO{sub 2}. Substantially less inhomogeneity of coating mixtures was found in films produced using a reactive sputtering process with feedback-control. - Highlights: • 61% and 137% increase in deposition rates of Nb{sub 2}O{sub 5} and SiO{sub 2} • Rugate coating designs can be readily deposited. • Nb{sub 2}O{sub 5}/SiO{sub 2} mixture films exhibited bulk or near-bulk density. • Optimized process leads to stoichiometric and homogenous mixtures. • Films are amorphous and suitable for low loss optical coatings.

  2. The Applications of Mixed Metal Oxides to Capture the CO2 and Convert to Syn-Gas

    Directory of Open Access Journals (Sweden)

    Sajan Babhare

    2015-07-01

    Full Text Available The applications of different mixed metal oxides were explored for the capture of CO2 and convert of CO2 to syn-gas. The several samples of the mixed metal oxides were prepared by the sol-gel, solid-solid fusion, precipitation, molten salt and template methods in order to investigate the performance of mixed mtal oxides to the CO2 applications. These samples were calcined for the 3 h in air at 900 oC. The mixed metal oxides samples were characterized by acidity/basicity, surface area, XRD pattern, SEM images and to capture CO2. The basicity and surface area of the samples of mixed metal oxides were found to be in the range from 0.7 to 15.7 mmol.g-1 and 2.24 to 138.76 m2.g-1, respectively. The ob-tained results of prepared mixed metal oxides by different method were compared for the purpose of searching the efficient materials. The temperature profiles of the captured CO2 by the samples of mixed metal oxides were obtained in the range 100 to 800 oC. The captured CO2 was found to be in the range from 7.36 to 26.93 wt.%. The conversions of CO2 by methane were explored to syn-gas over the mixed metal oxides including the calcium iron lanthanum mixed metal oxides and (5 wt.% Pd/Al2O3 at 700 oC with the gas hourly space velocities (GHSV 6000 ml.h-1.g-1 of methane, 6000 ml.h-1.g-1 of CO2 and 24000 ml.h-1.g-1 of helium.  © 2015 BCREC UNDIP. All rights reservedReceived: 23rd September 2014; Revised: 4th February 2015; Accepted: 5th February 2015How to Cite: Babhare, S., Raskar, R., Bobade, K., Gaikwad, A. (2015. The Applications of Mixed Metal Oxides to Capture the CO2 and Convert to Syn-Gas. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 125-142. (doi:10.9767/bcrec.10.2.7381.125-142Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.7381.125-142

  3. Fractionation of Cu and Zn isotopes during adsorption onto amorphous Fe(III) oxyhydroxide: Experimental mixing of acid rock drainage and ambient river water

    Science.gov (United States)

    Balistrieri, L.S.; Borrok, D.M.; Wanty, R.B.; Ridley, W.I.

    2008-01-01

    Fractionation of Cu and Zn isotopes during adsorption onto amorphous ferric oxyhydroxide is examined in experimental mixtures of metal-rich acid rock drainage and relatively pure river water and during batch adsorption experiments using synthetic ferrihydrite. A diverse set of Cu- and Zn-bearing solutions was examined, including natural waters, complex synthetic acid rock drainage, and simple NaNO3 electrolyte. Metal adsorption data are combined with isotopic measurements of dissolved Cu (65Cu/63Cu) and Zn (66Zn/64Zn) in each of the experiments. Fractionation of Cu and Zn isotopes occurs during adsorption of the metal onto amorphous ferric oxyhydroxide. The adsorption data are modeled successfully using the diffuse double layer model in PHREEQC. The isotopic data are best described by a closed system, equilibrium exchange model. The fractionation factors (??soln-solid) are 0.99927 ?? 0.00008 for Cu and 0.99948 ?? 0.00004 for Zn or, alternately, the separation factors (??soln-solid) are -0.73 ?? 0.08??? for Cu and -0.52 ?? 0.04??? for Zn. These factors indicate that the heavier isotope preferentially adsorbs onto the oxyhydroxide surface, which is consistent with shorter metal-oxygen bonds and lower coordination number for the metal at the surface relative to the aqueous ion. Fractionation of Cu isotopes also is greater than that for Zn isotopes. Limited isotopic data for adsorption of Cu, Fe(II), and Zn onto amorphous ferric oxyhydroxide suggest that isotopic fractionation is related to the intrinsic equilibrium constants that define aqueous metal interactions with oxyhydroxide surface sites. Greater isotopic fractionation occurs with stronger metal binding by the oxyhydroxide with Cu > Zn > Fe(II).

  4. Plutonium-uranium mixed oxide characterization by coupling micro-X-ray diffraction and absorption investigations

    Science.gov (United States)

    Degueldre, C.; Martin, M.; Kuri, G.; Grolimund, D.; Borca, C.

    2011-09-01

    Plutonium-uranium mixed oxide (MOX) fuels are currently used in nuclear reactors. The potential differences of metal redox state and microstructural developments of the matrix before and after irradiation are commonly analysed by electron probe microanalysis. In this work the structure and next-neighbor atomic environments of Pu and U oxide features within unirradiated homogeneous MOX and irradiated (60 MW d kg -1) MOX samples was analysed by micro-X-ray fluorescence (μ-XRF), micro-X-ray diffraction (μ-XRD) and micro-X-ray absorption fine structure (μ-XAFS) spectroscopy. The grain properties, chemical bonding, valences and stoichiometry of Pu and U are determined from the experimental data gained for the unirradiated as well as for irradiated fuel material examined in the center of the fuel as well as in its peripheral zone (rim). The formation of sub-grains is observed as well as their development from the center to the rim (polygonization). In the irradiated sample Pu remains tetravalent (>95%) and no (oxidation in the rim zone. Any slight potential plutonium oxidation is buffered by the uranium dioxide matrix while locally fuel cladding interaction could also affect the redox of the fuel.

  5. Solution processable broadband transparent mixed metal oxide nanofilm optical coatings via substrate diffusion doping.

    Science.gov (United States)

    Glynn, Colm; Aureau, Damien; Collins, Gillian; O'Hanlon, Sally; Etcheberry, Arnaud; O'Dwyer, Colm

    2015-12-21

    Devices composed of transparent materials, particularly those utilizing metal oxides, are of significant interest due to increased demand from industry for higher fidelity transparent thin film transistors, photovoltaics and a myriad of other optoelectronic devices and optics that require more cost-effective and simplified processing techniques for functional oxides and coatings. Here, we report a facile solution processed technique for the formation of a transparent thin film through an inter-diffusion process involving substrate dopant species at a range of low annealing temperatures compatible with processing conditions required by many state-of-the-art devices. The inter-diffusion process facilitates the movement of Si, Na and O species from the substrate into the as-deposited vanadium oxide thin film forming a composite fully transparent V0.0352O0.547Si0.4078Na0.01. Thin film X-ray diffraction and Raman scattering spectroscopy show the crystalline component of the structure to be α-NaVO3 within a glassy matrix. This optical coating exhibits high broadband transparency, exceeding 90-97% absolute transmission across the UV-to-NIR spectral range, while having low roughness and free of surface defects and pinholes. The production of transparent films for advanced optoelectronic devices, optical coatings, and low- or high-k oxides is important for planar or complex shaped optics or surfaces. It provides opportunities for doping metal oxides to ternary, quaternary or other mixed metal oxides on glass, encapsulants or other substrates that facilitate diffusional movement of dopant species. PMID:26575987

  6. Thermal and oxidation stability of organo-fluorine compound-mixed electrolyte solutions for lithium ion batteries

    Science.gov (United States)

    Nishikawa, Daiki; Nakajima, Tsuyoshi; Ohzawa, Yoshimi; Koh, Meiten; Yamauchi, Akiyoshi; Kagawa, Michiru; Aoyama, Hirokazu

    2013-12-01

    Thermal and oxidation stability of fluorine compound-mixed electrolyte solutions have been investigated. Charge/discharge behavior of natural graphite electrode has been also examined in the same electrolyte solutions. Fluorine compounds demonstrate much lower reactivity with metallic Li than ethylene carbonate/dimethyl carbonate. Fluorine compound-mixed electrolyte solutions show the lower reactivity with LiC6 and the smaller exothermic peaks due to decomposition of electrolyte solutions and surface films than original solutions without fluorine compound. Oxidation currents are also smaller in fluorine compound-mixed electrolyte solutions than in original ones. First coulombic efficiencies in fluorine compound-mixed electrolyte solutions are similar to those in original ethylene carbonate-based solutions except one case. Mixing of fluorine compounds highly increase first coulombic efficiencies of natural graphite electrode in propylene carbonate-containing solution.

  7. Evaluation of Co-precipitation Processes for the Synthesis of Mixed-Oxide Fuel Feedstock Materials

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Emory D [ORNL; Voit, Stewart L [ORNL; Vedder, Raymond James [ORNL

    2011-06-01

    The focus of this report is the evaluation of various co-precipitation processes for use in the synthesis of mixed oxide feedstock powders for the Ceramic Fuels Technology Area within the Fuels Cycle R&D (FCR&D) Program's Advanced Fuels Campaign. The evaluation will include a comparison with standard mechanical mixing of dry powders and as well as other co-conversion methods. The end result will be the down selection of a preferred sequence of co-precipitation process for the preparation of nuclear fuel feedstock materials to be used for comparison with other feedstock preparation methods. A review of the literature was done to identify potential nitrate-to-oxide co-conversion processes which have been applied to mixtures of uranium and plutonium to achieve recycle fuel homogeneity. Recent studies have begun to study the options for co-converting all of the plutonium and neptunium recovered from used nuclear fuels, together with appropriate portions of recovered uranium to produce the desired mixed oxide recycle fuel. The addition of recycled uranium will help reduce the safeguard attractiveness level and improve proliferation resistance of the recycled fuel. The inclusion of neptunium is primarily driven by its chemical similarity to plutonium, thus enabling a simple quick path to recycle. For recycle fuel to thermal-spectrum light water reactors (LWRs), the uranium concentration can be {approx}90% (wt.), and for fast spectrum reactors, the uranium concentration can typically exceed 70% (wt.). However, some of the co-conversion/recycle fuel fabrication processes being developed utilize a two-step process to reach the desired uranium concentration. In these processes, a 50-50 'master-mix' MOX powder is produced by the co-conversion process, and the uranium concentration is adjusted to the desired level for MOX fuel recycle by powder blending (milling) the 'master-mix' with depleted uranium oxide. In general, parameters that must be

  8. Computational and Experimental Study of the Thermodynamics of Uranium-Cerium Mixed Oxides

    Science.gov (United States)

    Hanken, Benjamin Edward

    The thermophysical properties of mixed oxide (MOX) fuels, and how they are influenced by the incorporation of fission products and other actinides, must be well understood for their safe use in an advanced fuel cycle. Cerium is a common plutonium surrogate in experimental studies of MOX, as it closely matches plutonium's ionic radii in the 3+ and 4+ oxidation states, and is soluble in fluorite-structured UO2. As a fission product, cerium's effects on properties of MOX are also of practical interest. To provide additional insights on structure-dependent behavior, urania solid solutions can be studied via density functional theory (DFT), although approaches beyond standard DFT are needed to properly account for the localized nature of the ƒ-electrons. In this work, DFT with Hubbard-U corrections (DFT+U) was employed to study the energetics of fluorite-structured U1-yCe yO2 mixtures. The employed computational approach makes use of a procedure which facilitates convergence of the calculations to multiple self-consistent DFT+U solutions for a given cation arrangement, corresponding to different charge states for the U and Ce ions in several prototypical cation arrangements. Results indicate a significant dependence of the structural and energetic properties of U1-yCeyO2 on the nature of both charge and cation ordering. With the effective Hubbard-U parameters that reproduce well the measured oxidation-reduction energies for urania and ceria, it was found that charge transfer between U4+ and Ce4+ ions, leading to the formation of U5+ and Ce3+, gives rise to an increase in the mixing energy in the range of 4-14 kJ/mol of the formula unit, depending on the nature of the cation ordering. In conjunction with the computational approach, high-temperature oxide-melt drop-solution calorimetry experiments were performed on eight samples spanning compositions of y = 0.119 to y = 0.815. Room temperature mixing enthalpies of U1-yCeyO2 determined from these experiments show near

  9. Study of sodium dodecyl sulfate-poly(propylene oxide) methacrylate mixed micelles.

    Science.gov (United States)

    Bastiat, Guillaume; Grassl, Bruno; Khoukh, Abdel; François, Jeanne

    2004-07-01

    Sodium dodecyl sulfate (SDS)-poly(propylene oxide) methacrylate (PPOMA) (of molecular weight M(w) = 434 g x mol(-1)) mixtures have been studied using conductimetry, static light scattering, fluorescence spectroscopy, and 1H NMR. It has been shown that SDS and PPOMA form mixed micelles, and SDS and PPOMA aggregation numbers, N(ag SDS) and N(ag PPOMA), have been determined. Total aggregation numbers of the micelles (N(ag SDS) + N(ag PPOMA)) and those of SDS decrease upon increasing the weight ratio R = PPOMA/SDS. Localization of PPOMA inside the mixed micelles is considered (i) using 1H NMR to localize the methacrylate function at the hydrophobic core-water interface and (ii) by studying the SDS-PPO micellar system (whose M(w) = 400 g x mol(-1)). Both methods have indicated that the PPO chain of the macromonomer is localized at the SDS micelle surface. Models based on the theorical prediction of the critical micellar concentration of mixed micelles and structural model of swollen micelles are used to confirm the particular structure proposed for the SDS-PPOMA system, i.e., the micelle hydrophobic core is primarily composed of the C12 chains of the sodium dodecyl sulfate, the hydrophobic core-water interface is made up of the SDS polar heads as well as methacrylate functions of the PPOMA, the PPO chains of the macromonomer are adsorbed preferentially on the surface, i.e., on the polar heads of the SDS.

  10. Water reactivity with mixed oxide (U,Pu)O2 surfaces

    International Nuclear Information System (INIS)

    The interaction of water with actinides oxide surfaces remains poorly understood. The adsorption of water on PuO2 surface and (U,Pu)O2 surface leads to hydrogen generation through radiolysis but also surface evolution. The study of water interaction with mixed oxide (U,Pu)O2 and PuO2 surfaces requires the implementation of non intrusive techniques. The study of the hydration of CeO2 surface is used to study the effectiveness of different techniques. The results show that the water adsorption leads to the surface evolution through the formation of a hydroxide superficial layer. The reactivity of water on the surface depends on the calcination temperature of the oxide precursor. The thermal treatment of hydrated surfaces can regenerate the surface. The study on CeO2 hydration emphasizes the relevancies of these techniques in studying the hydration of surfaces. The hydrogen generation through water radiolysis is studied with an experimental methodology based on constant relative humidity in the radiolysis cell. The hydrogen accumulation is linear for the first hours and then tends to a steady state content. A mechanism of hydrogen consumption is proposed to explain the existence of the steady state of hydrogen content. This mechanism enables to explain also the evolution of the oxide surface during hydrogen generation experiments as shown by the evolution of hydrogen accumulation kinetics. The accumulation kinetics depends on the dose rate, specific surface area and the relative humidity but also on the oxide aging. The plutonium percentage appears to be a crucial parameter in hydrogen accumulation kinetics. (author)

  11. High temperature X-ray diffraction study of the oxidation products and kinetics of uranium-plutonium mixed oxides.

    Science.gov (United States)

    Strach, Michal; Belin, Renaud C; Richaud, Jean-Christophe; Rogez, Jacques

    2014-12-15

    The oxidation products and kinetics of two sets of mixed uranium-plutonium dioxides containing 14%, 24%, 35%, 46%, 54%, and 62% plutonium treated in air were studied by means of in situ X-ray diffraction (XRD) from 300 to 1773 K every 100 K. The first set consisted of samples annealed 2 weeks before performing the experiments. The second one consisted of powdered samples that sustained self-irradiation damage. Results were compared with chosen literature data and kinetic models established for UO2. The obtained diffraction patterns were used to determine the temperature of the hexagonal M3O8 (M for metal) phase formation, which was found to increase with Pu content. The maximum observed amount of the hexagonal phase in wt % was found to decrease with Pu addition. We conclude that plutonium stabilizes the cubic phases during oxidation, but the hexagonal phase was observed even for the compositions with 62 mol % Pu. The results indicate that self-irradiation defects have a slight impact on the kinetics of oxidation and the lattice parameter even after the phase transformation. It was concluded that the lattice constant of the high oxygen phase was unaffected by the changes in the overall O/M when it was in equilibrium with small quantities of M3O8. We propose that the observed changes in the high oxygen cubic phase lattice parameter are a result of either cation migration or an increase in the miscibility of oxygen in this phase. The solubility of Pu in the hexagonal phase was estimated to be below 14 mol % even at elevated temperatures. PMID:25412433

  12. Combined removal of diesel soot particulates and NOx over CeO2–ZrO2 mixed oxides

    OpenAIRE

    Atribak, Idriss; Bueno López, Agustín; García García, Avelina

    2008-01-01

    CeO2 and Ce–Zr mixed oxides with different Ce:Zr ratios were prepared; characterised by Raman spectroscopy, XRD, TEM, N2 adsorption at −196 ◦C, and H2-TPR; and tested for soot oxidation under NOx/O2. Among the different mixed oxides, Ce0.76Zr0.24O2 provided the best results. Ce0.76Zr0.24O2 presented greater activity than pure CeO2 for soot oxidation by NOx/O2 when both catalysts were calcined at 500 ◦C (soot oxidation rates at 500 ◦C are 14.9 and 11.4 μgsoot/s, respectively), and ...

  13. Comparison of electrorheological performance between urea-coated and graphene oxide-wrapped core-shell structured amorphous TiO2 nanoparticles

    Science.gov (United States)

    Dong, Xufeng; Huo, Shuang; Qi, Min

    2016-01-01

    Polar molecules and graphene oxide (GO) have been used as the shell materials to prepare core-shell structured particles with enhanced electrorheological (ER) properties. Nevertheless, few studies compared the ER performance and stability of the suspensions with the two kinds of shell. In this study, urea and GO are used as the shell materials to prepare TiO2/urea and TiO2/GO core-shell particles-based ER fluids, respectively. Particle characterization results indicate the two kinds of core-shell structured particles present little change in size, morphology and crystal structure compared with the bare amorphous TiO2. Some polar groups are distributed on the surface of the two kinds of core-shell structured particles, which is responsible for their improved ER performance with respect to the bare TiO2 particles. The TiO2/GO particles-based ER fluid presents higher yield stress, lower leakage current density, better sedimentation stability but lower ER efficiency than the TiO2/urea particles-based sample. The larger surface area, stronger connection with the bare TiO2 particles, and larger number of polar groups of the GO-coating is the possible reason for the different properties of TiO2/GO particles-based ER fluid compared with the TiO2/urea particles-based sample.

  14. Effect of top gate potential on bias-stress for dual gate amorphous indium-gallium-zinc-oxide thin film transistor

    Science.gov (United States)

    Chun, Minkyu; Um, Jae Gwang; Park, Min Sang; Chowdhury, Md Delwar Hossain; Jang, Jin

    2016-07-01

    We report the abnormal behavior of the threshold voltage (VTH) shift under positive bias Temperature stress (PBTS) and negative bias temperature stress (NBTS) at top/bottom gate in dual gate amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). It is found that the PBTS at top gate shows negative transfer shift and NBTS shows positive transfer shift for both top and bottom gate sweep. The shift of bottom/top gate sweep is dominated by top gate bias (VTG), while bottom gate bias (VBG) is less effect than VTG. The X-ray photoelectron spectroscopy (XPS) depth profile provides the evidence of In metal diffusion to the top SiO2/a-IGZO and also the existence of large amount of In+ under positive top gate bias around top interfaces, thus negative transfer shift is observed. On the other hand, the formation of OH- at top interfaces under the stress of negative top gate bias shows negative transfer shift. The domination of VTG both on bottom/top gate sweep after PBTS/NBTS is obviously occurred due to thin active layer.

  15. Improvement in reliability of amorphous indium-gallium-zinc oxide thin-film transistors with Teflon/SiO2 bilayer passivation under gate bias stress

    Science.gov (United States)

    Fan, Ching-Lin; Tseng, Fan-Ping; Li, Bo-Jyun; Lin, Yu-Zuo; Wang, Shea-Jue; Lee, Win-Der; Huang, Bohr-Ran

    2016-02-01

    The reliability of amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) with Teflon/SiO2 bilayer passivation prepared under positive and negative gate bias stresses (PGBS and NGBS, respectively) was investigated. Heavier electrical degradation was observed under PGBS than under NGBS, indicating that the environmental effects under PGBS are more evident than those under NGBS. The device with bilayer passivation under PGBS shows two-step degradation. The positive threshold voltage shifts during the initial stressing period (before 500 s), owing to the charges trapped in the gate insulator or at the gate insulator/a-IGZO active layer interface. The negative threshold voltage shift accompanies the increase in subthreshold swing (SS) for the continuous stressing period (after 500 s) owing to H2O molecules from ambience diffused within the a-IGZO TFTs. It is believed that Teflon/SiO2 bilayer passivation can effectively improve the reliability of the a-IGZO TFTs without passivation even though the devices are stressed under gate bias.

  16. Effect of top gate bias on photocurrent and negative bias illumination stress instability in dual gate amorphous indium-gallium-zinc oxide thin-film transistor

    Science.gov (United States)

    Lee, Eunji; Chowdhury, Md Delwar Hossain; Park, Min Sang; Jang, Jin

    2015-12-01

    We have studied the effect of top gate bias (VTG) on the generation of photocurrent and the decay of photocurrent for back channel etched inverted staggered dual gate structure amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film-transistors. Upon 5 min of exposure of 365 nm wavelength and 0.7 mW/cm2 intensity light with negative bottom gate bias, the maximum photocurrent increases from 3.29 to 322 pA with increasing the VTG from -15 to +15 V. By changing VTG from negative to positive, the Fermi level (EF) shifts toward conduction band edge (EC), which substantially controls the conversion of neutral vacancy to charged one (VO → VO+/VO2+ + e-/2e-), peroxide (O22-) formation or conversion of ionized interstitial (Oi2-) to neutral interstitial (Oi), thus electron concentration at conduction band. With increasing the exposure time, more carriers are generated, and thus, maximum photocurrent increases until being saturated. After negative bias illumination stress, the transfer curve shows -2.7 V shift at VTG = -15 V, which gradually decreases to -0.42 V shift at VTG = +15 V. It clearly reveals that the position of electron quasi-Fermi level controls the formation of donor defects (VO+/VO2+/O22-/Oi) and/or hole trapping in the a-IGZO /interfaces.

  17. Improving source/drain contact resistance of amorphous indium–gallium–zinc-oxide thin-film transistors using an n+-ZnO buffer layer

    Science.gov (United States)

    Hung, Chien-Hsiung; Wang, Shui-Jinn; Lin, Chieh; Wu, Chien-Hung; Chen, Yen-Han; Liu, Pang-Yi; Tu, Yung-Chun; Lin, Tseng-Hsing

    2016-06-01

    To avoid high temperature annealing in improving the source/drain (S/D) resistance (R DS) of amorphous indium–gallium–zinc-oxide (α-IGZO) thin-film transistors (TFTs) for flexible electronics, a simple and efficient technique using a sputtering-deposited n+-ZnO buffer layer (BL) sandwiched between the S/D electrode and the α-IGZO channel is proposed and demonstrated. It shows that the R DS of α-IGZO TFTs with the proposed n+-ZnO BL is reduced to 8.1 × 103 Ω as compared with 6.1 × 104 Ω of the conventional one. The facilitation of carrier tunneling between the S/D electrode and the α-IGZO channel through the use of the n+-ZnO BL to lower the effective barrier height therein is responsible for the R DS reduction. Effects of the chamber pressure on the carrier concentration of the sputtering-deposited n+-ZnO BL and the thickness of the BL on the degree of improvement in the performance of α-IGZO TFTs are analyzed and discussed.

  18. Characterization of CeO2-ZrO2 mixed oxides prepared by two different co-precipitation methods

    Institute of Scientific and Technical Information of China (English)

    YUE Mei; CUI Meisheng; ZHANG Na; LONG Zhiqi; HUANG Xiaowei

    2013-01-01

    A series of cerium zirconium mixed oxides were prepared by two co-precipitation methods using magnesium hydrogen carbonate (MHC) and mixed ammonia-ammonia hydrogen carbonate (AAHC) as precipitant respectively.The crystal structure,BET surface area and morphology of the produced cerium zirconium mixed oxides were characterized by X-ray diffraction (XRD),Brumauer-Emmett-Teller (BET) and scanning electron microscopy (SEM) techniques.The reduction-oxidation behavior and oxygen storage capacity (OSC) performance were also studied by temperature programmed reduction (TPR) and oxygen pulse chemical adsorption methods.The XRD results demonstrated that the cerium zirconium mixed oxides obtained by both methods possessed structure of cubic solid solution phase.The fresh surface area calcinated at 600 ℃,aged surface area after 1000 ℃ and OSC at 500 ℃ of cerium zirconium mixed oxides were determined to be 89.337,34.784 m2/g,and 567 μmol O2/g for MHC method and 122.010,46.307 m2/g,and 665 μmol O2/g for AAHC method,respectively.

  19. Shrinking of silicon nanocrystals embedded in an amorphous silicon oxide matrix during rapid thermal annealing in a forming gas atmosphere

    Science.gov (United States)

    van Sebille, M.; Fusi, A.; Xie, L.; Ali, H.; van Swaaij, R. A. C. M. M.; Leifer, K.; Zeman, M.

    2016-09-01

    We report the effect of hydrogen on the crystallization process of silicon nanocrystals embedded in a silicon oxide matrix. We show that hydrogen gas during annealing leads to a lower sub-band gap absorption, indicating passivation of defects created during annealing. Samples annealed in pure nitrogen show expected trends according to crystallization theory. Samples annealed in forming gas, however, deviate from this trend. Their crystallinity decreases for increased annealing time. Furthermore, we observe a decrease in the mean nanocrystal size and the size distribution broadens, indicating that hydrogen causes a size reduction of the silicon nanocrystals.

  20. Microbial Ecology Assessment of Mixed Copper Oxide/Sulfide Dump Leach Operation

    Energy Technology Data Exchange (ETDEWEB)

    Bruhn, D F; Thompson, D N; Noah, K S

    1999-06-01

    Microbial consortia composed of complex mixtures of autotrophic and heterotrophic bacteria are responsible for the dissolution of metals from sulfide minerals. Thus, an efficient copper bioleaching operation depends on the microbial ecology of the system. A microbial ecology study of a mixed oxide/sulfide copper leaching operation was conducted using an "overlay" plating technique to differentiate and identify various bacterial consortium members of the genera Thiobacillus, Leptospirillum, Ferromicrobium, and Acidiphilium. Two temperatures (30C and 45C) were used to select for mesophilic and moderately thermophilic bacteria. Cell numbers varied from 0-106 cells/g dry ore, depending on the sample location and depth. After acid curing for oxide leaching, no viable bacteria were recovered, although inoculation of cells from raffinate re-established a microbial population after three months. Due to the low pH of the operation, very few non-iron-oxidizing acidophilic heterotrophs were recovered. Moderate thermophiles were isolated from the ore samples. Pregnant liquor solutions (PLS) and raffinate both contained a diversity of bacteria. In addition, an intermittently applied waste stream that contained high levels of arsenic and fluoride was tested for toxicity. Twenty vol% waste stream in PLS killed 100% of the cells in 48 hours, indicating substantial toxicity and/or growth inhibition. The data indicate that bacteria populations can recover after acid curing, and that application of the waste stream to the dump should be avoided. Monitoring the microbial ecology of the leaching operation provided significant information that improved copper recovery.

  1. Using amorphous manganese oxide for remediation of smelter-polluted soils: a pH-dependent long-term stability study

    Science.gov (United States)

    Ettler, Vojtech; Tomasova, Zdenka; Komarek, Michael; Mihaljevic, Martin; Sebek, Ondrej

    2015-04-01

    In soil systems, manganese (Mn) oxides are commonly found to be powerful sorbents of metals and metalloids and are thus potentially useful in soil remediation. A novel amorphous manganese oxide (AMO) and a Pb smelter-polluted agricultural soil amended with the AMO and incubated for 2 and 6 months were subjected to a pH-static leaching procedure (pH = 3 - 8) to verify the chemical stabilization effect on metals and metalloids. The AMO stability in pure water was pH-dependent with the highest Mn release at pH 3 (47% dissolved) and the lowest at pH 8 (0.14% dissolved). Secondary rhodochrosite (MnCO3) was formed at the AMO surfaces at pH > 5. The AMO dissolved significantly less after 6 months of incubation. Sequential extraction analysis indicated that "labile" fraction of As, Pb and Sb in soil significantly decreased after AMO amendment. The pH-static experiments indicated that no effect on leaching was observed for Cd and Zn after AMO treatments, whereas the leaching of As, Cu, Pb and Sb decreased down to 20%, 35%, 7% and 11% of the control, respectively. The remediation efficiency was more pronounced under acidic conditions and the time of incubation generally led to increased retention of the targeted contaminants. The AMO was found to be a promising agent for the chemical stabilization of polluted soils and other in situ applications need to be evaluated. This study was supported by the Czech Science Foundation (GAČR 15-07117S).

  2. Effect of different mixing ways in palladium/ceria-zirconia/alumina preparation on partial oxidation of methane

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qingwei; WEN Jing; SHEN Meiqing; WANG Jun

    2008-01-01

    The effect of the mixing ways of Ce0.7Zr0.3O2-Al2O3 mixed oxides on the partial oxidations of methane (POM) was investigated over Pd/Ce0.7Zr0.3O2-Al2O3 catalysts, the mixing ways including salt precursor mixing (ATOM), precipitator mixing (MOL), and powder mechanically mixing (MECH), respectively. The test results indicated that among the three samples, Pd/ATOM had the best catalytic activity,while Pd/MOL had the best stability in the stability test. Both the activity sequences of the fresh and used samples were consistent with the order of Pd dispersion. According to the X-ray diffraction (XRD) and BET characterization, the interaction of Ce4+, Zr4+, and Al3+ in the ATOM mixed oxide was in favor of performing higher catalytic activity and thermal stability. The stability test indicated that Pd/MOL had the highest Pd dispersion and least coke formation on the active sites calculated by the H2-chemisorption and TG results, which was consid-ered to relate to its superior activity of POM to other catalysts.

  3. Electrolytic reduction of mixed (Fe, Ti) oxide using molten calcium chloride electrolyte

    International Nuclear Information System (INIS)

    Highlights: ► Tan et al. have electrolyzed mixtures of TiO2 and Fe2O3 to produce alloys containing Fe–Ti intermetallic phases such as FeTi and Fe2Ti using the FFC process. However, the produced alloys have a porous structure with many carbon impurities, e.g., titanium carbide (TiC). Most of the carbon contamination could be caused by the presence of carbon particles in the porous alloy structure. They did not mention any obvious ways of excluding carbon and other impurities, and only suggested that the use of mixed oxides with refined structures or using a single phase, namely ilmenite (FeO·TiO2), were methods of decreasing impurities in the formed alloys. For future industrialization, there is an urgent need for obvious ways of producing purer Fe–Ti alloys with dense structures, rather than porous structures, as these absorb carbon impurities. ► Finally, we successfully reduced to a highly purified Fe–Ti intermetallic alloy of FeTi and β-Ti (FeTi4) phases. FeTi phases of size around 5–10 μm were dispersed in a matrix of the β-Ti (FeTi4) phase. The carbon content of the electrolyzed alloy was as low as less than 0.01 mass%. It was suggested that the dense structure of the alloy of FeTi and β-Ti (FeTi4) avoided the inclusion of carbon particle impurities, unlike the porous alloy structure. - Abstract: The production of high-purity metals or alloys using effective technologies is critical for future industrialization. With this aim in mind, a fundamental study of electrolysis in molten CaCl2 electrolytes was conducted to develop a new production process for ferrotitanium (Fe–Ti) intermetallic alloys. Mixed solid oxides of TiO2 and Fe2O3 were used in a molar ratio of 5.44:1.00. In this composition of Ti and Fe, FeTi and β-Ti containing iron can co-exist in equilibrium. A mixed solid (Fe, Ti) oxide was reduced electrochemically in a molten CaCl2 electrolyte at 950 °C. The metallic samples formed by electrolytic reduction of the mixed solid (Fe, Ti

  4. Cu–Ce–O mixed oxides from Ce-containing layered double hydroxide precursors: Controllable preparation and catalytic performance

    International Nuclear Information System (INIS)

    Cu/Zn/Al layered double hydroxide (LDH) precursors have been synthesized using an anion exchange method with anionic Ce complexes containing the dipicolinate (pyridine-2,6-dicarboxylate) ligand. Cu–Ce–O mixed oxides were obtained by calcination of the Ce-containing LDHs. The materials were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetry–differential thermal analysis, elemental analysis, and low temperature N2 adsorption/desorption measurements. The results reveal that the inclusion of Ce has a significant effect on the specific surface area, pore structure, and chemical state of Cu in the resulting Cu–Ce–O mixed metal oxides. The resulting changes in composition and structure, particularly the interactions between Cu and Ce centers, significantly enhance the activity of the Ce-containing materials as catalysts for the oxidation of phenol by hydrogen peroxide. - Graphical Abstract: Cu–Ce–O mixed oxides calcined from [Ce(dipic)3]3−- intercalated Cu/Zn/Al layered double hydroxides were synthesized and displayed good catalytic performances in phenol oxidation due to the Cu–Ce interactions. Highlights: ► [Ce(dipic)3]3−-intercalated Cu/Zn/Al layered double hydroxides were synthesized. ► Cu–Ce–O mixed oxides derivated from the LDHs were characterized as catalysts. ► Presence of Ce influenced physicochemical property and catalytic performance. ► Cu–Ce interaction was largely responsible for enhanced catalytic ability.

  5. Interplay between hopping and band transport in high-mobility disordered semiconductors at large carrier concentrations: The case of the amorphous oxide InGaZnO

    Science.gov (United States)

    Fishchuk, I. I.; Kadashchuk, A.; Bhoolokam, A.; de Jamblinne de Meux, A.; Pourtois, G.; Gavrilyuk, M. M.; Köhler, A.; Bässler, H.; Heremans, P.; Genoe, J.

    2016-05-01

    We suggest an analytic theory based on the effective medium approximation (EMA) which is able to describe charge-carrier transport in a disordered semiconductor with a significant degree of degeneration realized at high carrier concentrations, especially relevant in some thin-film transistors (TFTs), when the Fermi level is very close to the conduction-band edge. The EMA model is based on special averaging of the Fermi-Dirac carrier distributions using a suitably normalized cumulative density-of-state distribution that includes both delocalized states and the localized states. The principal advantage of the present model is its ability to describe universally effective drift and Hall mobility in heterogeneous materials as a function of disorder, temperature, and carrier concentration within the same theoretical formalism. It also bridges a gap between hopping and bandlike transport in an energetically heterogeneous system. The key assumption of the model is that the charge carriers move through delocalized states and that, in addition to the tail of the localized states, the disorder can give rise to spatial energy variation of the transport-band edge being described by a Gaussian distribution. It can explain a puzzling observation of activated and carrier-concentration-dependent Hall mobility in a disordered system featuring an ideal Hall effect. The present model has been successfully applied to describe experimental results on the charge transport measured in an amorphous oxide semiconductor, In-Ga-Zn-O (a-IGZO). In particular, the model reproduces well both the conventional Meyer-Neldel (MN) compensation behavior for the charge-carrier mobility and inverse-MN effect for the conductivity observed in the same a-IGZO TFT. The model was further supported by ab initio calculations revealing that the amorphization of IGZO gives rise to variation of the conduction-band edge rather than to the creation of localized states. The obtained changes agree with the one we

  6. Hydrothermal Synthesis, Characterization and Catalytic Properties of Nanoporous MoO3/ZrO2 Mixed Oxide

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A nanoporous MoO3/ZrO2 mixed oxide was hydrothermally synthesized by hydrolyzing zirconium isopropoxide in the presence of a cationic surfactant, cetyltrimethylammonium bromide(CTAB). The crystal structure and the acidity of the obtained nanoporous MoO3/ZrO2 mixed oxide were determined by means of XRD, N2 adsorption-desorption and NH3-TPD, respectively. The isobutane/butene alkylation over the MoO3/ZrO2 catalyst was carried out in a fixed bed reactor. The results reveal that ZrO2 in MoO3/ZrO2 exists mainly in the tetragonal phase, and the catalyst samples possess large specific surface areas as well as moderate acidity for isobutane/butene alkylation. Compared with samples prepared by impregnation and sol-gel processes, MoO3/ZrO2 mixed oxide samples prepared in this work have a better catalytic activity.

  7. Influence of thermal treatments on the basic and catalytic properties of Mg,Al-mixed oxides derived from hydrotalcites

    Directory of Open Access Journals (Sweden)

    R. Bastiani

    2004-06-01

    Full Text Available This work studied the influence of calcination conditions on basic properties and catalytic performance of Mg,Al-mixed oxides derived from a hydrotalcite sample (Al/(Al+Mg=0.20. Various heating rates, calcination atmospheres and lengths of calcination at 723K were evaluated. TPD of CO2 and retroaldolization of diacetone alcohol (DAA were used to determine the basic properties of the mixed oxides. The basic site density determined by TPD of CO2 showed a better correlation with catalytic activity for acetone/citral aldol condensation than the relative basicity obtained from retroaldolization of DAA. Calcination atmosphere was the parameter that influenced most the basic and the catalytic properties of the Mg,Al-mixed oxides, with calcination under dry air being the best choice.

  8. Bright blue photoluminescence from a mixed tin and manganese oxide xerogel prepared via sol-hydrothermal-gel process

    Institute of Scientific and Technical Information of China (English)

    Xiang Xia; Cheng Xiao-Feng; He Shao-Bo; Yuan Xiao-Dong; Zheng Wan-Guo; Li Zhi-Jie; Liu Chun-Ming; Zhou Wei-Lie; Zu Xiao-Tao

    2011-01-01

    A new blue photoluminescent material,a mixed tin and manganese oxide xerogel,is prepared via sol-hydrothermalgel process assisted by citric acid.The composition xerogel exhibits strong blue emission at room temperature,with an emission maximum at 434 nm under short (234 nm) or long-wavelength (343 nm) ultraviolet excitation.The photoluminescent excitation spectrum of the mixed tin and manganese oxide xerogel,monitored at an intensity maximum wavelength of 434 nm of the emission,consists of two excitation peaks at 234 nm and 343 nm.With heat treatment temperature increasing from 110 ℃ to 200 ℃,the blue emission intensity increases remarkably,whereas it is almost completely quenched after being treated at 300 ℃.The carbon impurities in the mixed tin and manganese oxide xerogel,confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy,should be responsible for the bright blue photoluminescence.

  9. Nanoporous composites prepared by a combination of SBA-15 with Mg-Al mixed oxides. Water vapor sorption properties.

    Science.gov (United States)

    Pérez-Verdejo, Amaury; Sampieri, Alvaro; Pfeiffer, Heriberto; Ruiz-Reyes, Mayra; Santamaría, Juana-Deisy; Fetter, Geolar

    2014-01-01

    This work presents two easy ways for preparing nanostructured mesoporous composites by interconnecting and combining SBA-15 with mixed oxides derived from a calcined Mg-Al hydrotalcite. Two different Mg-Al hydrotalcite addition procedures were implemented, either after or during the SBA-15 synthesis (in situ method). The first procedure, i.e., the post-synthesis method, produces a composite material with Mg-Al mixed oxides homogeneously dispersed on the SBA-15 nanoporous surface. The resulting composites present textural properties similar to the SBA-15. On the other hand, with the second procedure (in situ method), Mg and Al mixed oxides occur on the porous composite, which displays a cauliflower morphology. This is an important microporosity contribution and micro and mesoporous surfaces coexist in almost the same proportion. Furthermore, the nanostructured mesoporous composites present an extraordinary water vapor sorption capacity. Such composites might be utilized as as acid-base catalysts, adsorbents, sensors or storage nanomaterials.

  10. Nanoporous composites prepared by a combination of SBA-15 with Mg–Al mixed oxides. Water vapor sorption properties

    Directory of Open Access Journals (Sweden)

    Amaury Pérez-Verdejo

    2014-08-01

    Full Text Available This work presents two easy ways for preparing nanostructured mesoporous composites by interconnecting and combining SBA-15 with mixed oxides derived from a calcined Mg–Al hydrotalcite. Two different Mg–Al hydrotalcite addition procedures were implemented, either after or during the SBA-15 synthesis (in situ method. The first procedure, i.e., the post-synthesis method, produces a composite material with Mg–Al mixed oxides homogeneously dispersed on the SBA-15 nanoporous surface. The resulting composites present textural properties similar to the SBA-15. On the other hand, with the second procedure (in situ method, Mg and Al mixed oxides occur on the porous composite, which displays a cauliflower morphology. This is an important microporosity contribution and micro and mesoporous surfaces coexist in almost the same proportion. Furthermore, the nanostructured mesoporous composites present an extraordinary water vapor sorption capacity. Such composites might be utilized as as acid-base catalysts, adsorbents, sensors or storage nanomaterials.

  11. Criticality safety aspects in the fabrication of mixed oxide fuel for light water reactors

    International Nuclear Information System (INIS)

    Criticality safety aspects in the fabrication of (Pu, nat.U) mixed oxide fuel (MOX) for commercial light water reactors are discussed in this paper. Maximum PuO2 content in the MOX fuel is assumed as 4 wt%. The flowsheet that is mostly adopted for MOX fuel fabrication involves mechanical blending of PuO2 and nat. UO2 powders. Most of the process steps in the fabrication require handling of unmoderated fissile materials in leak tight glove box enclosures and criticality safety may not seriously limit the batch size and throughput of the MOX plants. However, radiation safety considerations that arise in the handling of high exposure Pu are likely to be more restrictive. Criticality safety limits for dry and wet operations and in storage of fuel are discussed. (author). 1 ref., 1 fig., 3 tabs

  12. Americium and plutonium release behavior from irradiated mixed oxide fuel during heating

    Science.gov (United States)

    Sato, I.; Suto, M.; Miwa, S.; Hirosawa, T.; Koyama, S.

    2013-06-01

    The release behavior of Pu and Am was investigated under the reducing atmosphere expected in sodium cooled fast reactor severe accidents. Irradiated Pu and U mixed oxide fuels were heated at maximum temperatures of 2773 K and 3273 K. EPMA, γ-ray spectrometry and α-ray spectrometry for released and residual materials revealed that Pu and Am can be released more easily than U under the reducing atmosphere. The respective release rate coefficients for Pu and Am were obtained as 3.11 × 10-4 min-1 and 1.60 × 10-4 min-1 at 2773 K under the reducing atmosphere with oxygen partial pressure less than 0.02 Pa. Results of thermochemical calculations indicated that the main released chemical forms would likely be PuO for Pu and Am for Am under quite low oxygen partial pressure.

  13. Molecular data of mixed metal oxides with importance in nuclear safety

    Science.gov (United States)

    Kovács, Attila; Konings, Rudy J. M.

    2016-08-01

    The gas-phase structural and spectroscopic properties of selected mixed metal oxides (Cs2CrO4, Cs2MnO4, Cs2MoO4, Cs2RuO4, BaMoO4, BaMoO3) have been calculated using Density Functional Theory (DFT). The possible structural isomers have been analyzed and for the found global minima the vibrational (IR, Raman) spectra have been predicted taking into account also anharmonic corrections. The bonding properties have been characterized by means of the Natural Bond Orbital analysis model while the low-lying excited electronic states have been calculated using time-dependent DFT. In order to assess the stability of the target species the dissociation enthalpies have been evaluated.

  14. Americium and plutonium release behavior from irradiated mixed oxide fuel during heating

    International Nuclear Information System (INIS)

    The release behavior of Pu and Am was investigated under the reducing atmosphere expected in sodium cooled fast reactor severe accidents. Irradiated Pu and U mixed oxide fuels were heated at maximum temperatures of 2773 K and 3273 K. EPMA, γ-ray spectrometry and α-ray spectrometry for released and residual materials revealed that Pu and Am can be released more easily than U under the reducing atmosphere. The respective release rate coefficients for Pu and Am were obtained as 3.11 × 10−4 min−1 and 1.60 × 10−4 min−1 at 2773 K under the reducing atmosphere with oxygen partial pressure less than 0.02 Pa. Results of thermochemical calculations indicated that the main released chemical forms would likely be PuO for Pu and Am for Am under quite low oxygen partial pressure

  15. Development of a digital-analogue robotic system for input solution and mixed oxide samples

    International Nuclear Information System (INIS)

    Automated analytical systems for uranium and plutonium samples have been under development at the Nuclear Material Control Center (NMCC) since 1983. These include two systems for a large scale reprocessing plant for measurement of input solution samples and for measurement of mixed oxide (MOX) samples using automated destructive analysis procedures. Diverse tasks, such as designing the enclosures, developing the control systems and performing preparatory experiments, were combined. On the basis of NMCC's routine manual analysis, input solution sample analysis employing the isotope dilution method has been automated. A new method has been applied to automate the analysis of MOX powder samples. This method uses glass bead samples prepared by the system. Each sample may have different properties; therefore each is processed in different enclosures. The methods for the two analyses were quite different. The technical considerations were based on NMCC's ten years of expertise in nuclear material analysis. (author). 4 refs

  16. The underwater coincidence counter for plutonium measurements in mixed-oxide fuel assemblies manual

    Energy Technology Data Exchange (ETDEWEB)

    G. W. Eccleston; H. O. Menlove; M. Abhold; M. Baker; J. Pecos

    1999-05-01

    This manual describes the Underwater Coincidence Counter (UWCC) that has been designed for the measurement of plutonium in mixed-oxide (MOX) fuel assemblies prior to irradiation. The UWCC uses high-efficiency {sup 3}He neutron detectors to measure the spontaneous-fission and induced-fission rates in the fuel assembly. Measurements can be made on MOX fuel assemblies in air or underwater. The neutron counting rate is analyzed for singles, doubles, and triples time correlations to determine the {sup 240}Pu effective mass per unit length of the fuel assembly. The system can verify the plutonium loading per unit length to a precision of less than 1% in a measurement time of 2 to 3 minutes. System design, components, performance tests, and operational characteristics are described in this manual.

  17. High temperature oxidation behaviour of nanostructured cermet coatings in a mixed CO2 – O2 environment

    International Nuclear Information System (INIS)

    Nanostructured ceramic-metallic (cermet) coatings composed of nanosized ceramic particles (α-Al2O3 and TiO2) dispersed in a nickel matrix were co-electrodeposited and then oxidized at 500°C, 600°C and 700°C in a mixed gas using a Thermo-gravimetric Analysis (TGA) apparatus. The mixed gas was composed of 15% CO2, 10% O2 and 75% N2. This research investigates the effects of CO2 and O2 partial pressures on time-depended oxidation rates for coatings and compared them to the results from atmospheric oxidation under similar temperatures. The increase in partial pressure of oxygen due to the presence of CO2 at each tested temperature was calculated and correlated to the oxidation rate of the coatings. The results showed that the presence of CO2 in the system increased the oxidation rate of cermet coatings when compared to atmospheric oxidation at the same temperature. It was also shown that the increase in the oxidation rate is not the result of CO2 acting as the primary oxidant but as a secondary oxidant which results in an increase of the total partial pressure of oxygen and consequently higher oxidation rates. The WDS and XRD analyses results showed that the presence of nanosized TiO2 particles in a nickel matrix can improve oxidation behaviour of the coatings by formation of Ni-Ti compounds on oxidizing surface of the coating which was found beneficiary in reducing the oxidation rates for cermet coatings

  18. Conversion of Syngas-Derived C2+ Mixed Oxygenates to C3-C5 Olefins over ZnxZryOz Mixed Oxides Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Colin D.; Lebarbier, Vanessa M.; Flake, Matthew D.; Ramasamy, Karthikeyan K.; Kovarik, Libor; Bowden, Mark E.; Onfroy, Thomas; Dagle, Robert A.

    2016-04-01

    In this study we report on a ZnxZryOz mixed oxide type catalyst capable of converting a syngas-derived C2+ mixed oxygenate feedstock to isobutene-rich olefins. Aqueous model feed comprising of ethanol, acetaldehyde, acetic acid, ethyl acetate, methanol, and propanol was used as representative liquid product derived from a Rh-based mixed oxygenate synthesis catalyst. Greater than 50% carbon yield to C3-C5 mixed olefins was demonstrated when operating at 400-450oC and 1 atm. In order to rationalize formation of the products observed feed components were individually evaluated. Major constituents of the feed mixture (ethanol, acetaldehyde, acetic acid, and ethyl acetate) were found to produce isobutene-rich olefins. C-C coupling was also demonstrated for propanol feedstock - a minor constituent of the mixed oxygenate feed - producing branched C6 olefins, revealing scalability to alcohols higher than ethanol following an analogous reaction pathway. Using ethanol and propanol feed mixtures, cross-coupling reactions produced mixtures of C4, C5, and C6 branched olefins. The presence of H2 in the feed was found to facilitate hydrogenation of the ketone intermediates, thus producing straight chain olefins as byproducts. While activity loss from coking is observed complete catalyst regeneration is achieved by employing mild oxidation. For conversion of the mixed oxygenate feed a Zr/Zn ratio of 2.5 and a reaction temperature of 450oC provides the best balance of stability, activity, and selectivity. X-ray diffraction and scanning transmission electron microscopy analysis reveals the presence of primarily cubic phase ZrO2 and a minor amount of the monoclinic phase, with ZnO being highly dispersed in the lattice. The presence of ZnO appears to stabilize the cubic phase resulting in less monoclinic phase as the ZnO concentration increases. Infrared spectroscopy shows the mixed oxide acid sites are characterized as primarily Lewis type acidity. The direct relationship between

  19. Evaluation of tubular reactor designs for supercritical water oxidation of U.S. Department of Energy mixed waste

    International Nuclear Information System (INIS)

    Supercritical water oxidation (SCWO) is an emerging technology for industrial waste treatment and is being developed for treatment of the US Department of Energy (DOE) mixed hazardous and radioactive wastes. In the SCWO process, wastes containing organic material are oxidized in the presence of water at conditions of temperature and pressure above the critical point of water, 374 C and 22.1 MPa. DOE mixed wastes consist of a broad spectrum of liquids, sludges, and solids containing a wide variety of organic components plus inorganic components including radionuclides. This report is a review and evaluation of tubular reactor designs for supercritical water oxidation of US Department of Energy mixed waste. Tubular reactors are evaluated against requirements for treatment of US Department of Energy mixed waste. Requirements that play major roles in the evaluation include achieving acceptable corrosion, deposition, and heat removal rates. A general evaluation is made of tubular reactors and specific reactors are discussed. Based on the evaluations, recommendations are made regarding continued development of supercritical water oxidation reactors for US Department of Energy mixed waste

  20. High-level neutron-coincidence-counter (HLNCC) implementation: assay of the plutonium content of mixed-oxide fuel assemblies

    International Nuclear Information System (INIS)

    The portable High-Level Neutron Coincidence Counter is used to assay the 240Pu-effective loading of a reference mixed-oxide fuel assembly by neutron coincidence counting. We have investigated the effects on the coincidence count rate of the total fuel loading (UO2 + PuO2), the fissile loading, the fuel rod diameter, and the fuel rod pattern. The coincidence count rate per gram of 240Pu-effective per centimeter is primarily dependent on the total fuel loading of the assembly; the higher the loading, the higher the coincidence count rate. Detailed procedures for the assay of mixed-oxide fuel assemblies are developed

  1. Role of flue gas components in mercury oxidation over TiO2 supported MnOx-CeO2 mixed-oxide at low temperature.

    Science.gov (United States)

    Li, Hailong; Wu, Chang-Yu; Li, Ying; Li, Liqing; Zhao, Yongchun; Zhang, Junying

    2012-12-01

    MnO(x)-CeO(2) mixed-oxide supported on TiO(2) (Mn-Ce/Ti) was synthesized by an ultrasound-assisted impregnation method and employed to oxidize elemental mercury (Hg(0)) at 200°C in simulated coal combustion flue gas. Over 90% of Hg(0) oxidation was achieved on the Mn-Ce/Ti catalyst at 200°C under simulated flue gas representing those from burning low-rank coals with a high gas hourly space velocity of 60,000 h(-1). Gas-phase O(2) regenerated the lattice oxygen and replenished the chemisorbed oxygen, which facilitated Hg(0) oxidation. HCl was the most effective flue gas component responsible for Hg(0) oxidation. 10 ppm HCl plus 4% O(2) resulted in 100% Hg(0) oxidation under the experimental conditions. SO(2) competed with Hg(0) for active sites, thus deactivating the catalyst's capability in oxidizing Hg(0). NO covered the active sites and consumed surface oxygen active for Hg(0) oxidation, hence limiting Hg(0) oxidation. Water vapor showed prohibitive effect on Hg(0) oxidation due to its competition with HCl and Hg(0) for active adsorption sites. This study provides information about the promotional or inhibitory effects of individual flue gas components on Hg(0) oxidation over a highly effective Mn-Ce/Ti catalyst. Such knowledge is of fundamental importance for industrial applications of the Mn-Ce/Ti catalyst in coal-fired power plants. PMID:23131500

  2. Mixed fuel strategy for carbon deposition mitigation in solid oxide fuel cells at intermediate temperatures.

    Science.gov (United States)

    Su, Chao; Chen, Yubo; Wang, Wei; Ran, Ran; Shao, Zongping; Diniz da Costa, João C; Liu, Shaomin

    2014-06-17

    In this study, we propose and experimentally verified that methane and formic acid mixed fuel can be employed to sustain solid oxide fuel cells (SOFCs) to deliver high power outputs at intermediate temperatures and simultaneously reduce the coke formation over the anode catalyst. In this SOFC system, methane itself was one part of the fuel, but it also played as the carrier gas to deliver the formic acid to reach the anode chamber. On the other hand, the products from the thermal decomposition of formic acid helped to reduce the carbon deposition from methane cracking. In order to clarify the reaction pathways for carbon formation and elimination occurring in the anode chamber during the SOFC operation, O2-TPO and SEM analysis were carried out together with the theoretical calculation. Electrochemical tests demonstrated that stable and high power output at an intermediate temperature range was well-maintained with a peak power density of 1061 mW cm(-2) at 750 °C. With the synergic functions provided by the mixed fuel, the SOFC was running for 3 days without any sign of cell performance decay. In sharp contrast, fuelled by pure methane and tested at similar conditions, the SOFC immediately failed after running for only 30 min due to significant carbon deposition. This work opens a new way for SOFC to conquer the annoying problem of carbon deposition just by properly selecting the fuel components to realize their synergic effects.

  3. The incorporation of graphene oxide into polysulfone mixed matrix membrane for CO2/CH4 separation

    Science.gov (United States)

    Zahri, K.; Goh, P. S.; Ismail, A. F.

    2016-06-01

    Carbon dioxide (CO2) is often found as the main impurity in natural gas, where methane (CH4) is the major component. The presence of CO2 in natural gas leads to several problems such as reducing the energy content of natural gas and cause pipeline corrosion. Thus it must be removed to meet specifications (CO2 ≤ 2 mol%) before the gas can be delivered to the pipeline. In this work, hollow fiber mixed matrix membrane (MMM) were fabricated by embedding graphene oxide (GO) into a polysulfone (PSf) polymer matrix to improve membrane properties as well as its separation performance towards CO2/CH4 gas. The membrane properties were investigated for pristine membrane and mixed matrix membrane filled with filler loading of 0.25%. The synthesized GO and properties of fabricated membranes were characterized and studied using TEM, AFM, XRD, FTIR and SEM respectively. The permeance of pure gases and ideal selectivity of CO2/CH4 gas were determined using pure gas permeation experiment. GO has affinity towards CO2 gas. The nanosheet structure creates path for small molecule gas and restricted large molecule gas to pass through the membrane. The incorporation of GO in PSf polymer enhanced the permeance of CO 2 and CO2/CH4 separation from 64.47 to 86.80 GPU and from 19 to 25 respectively.

  4. Mixed fuel strategy for carbon deposition mitigation in solid oxide fuel cells at intermediate temperatures.

    Science.gov (United States)

    Su, Chao; Chen, Yubo; Wang, Wei; Ran, Ran; Shao, Zongping; Diniz da Costa, João C; Liu, Shaomin

    2014-06-17

    In this study, we propose and experimentally verified that methane and formic acid mixed fuel can be employed to sustain solid oxide fuel cells (SOFCs) to deliver high power outputs at intermediate temperatures and simultaneously reduce the coke formation over the anode catalyst. In this SOFC system, methane itself was one part of the fuel, but it also played as the carrier gas to deliver the formic acid to reach the anode chamber. On the other hand, the products from the thermal decomposition of formic acid helped to reduce the carbon deposition from methane cracking. In order to clarify the reaction pathways for carbon formation and elimination occurring in the anode chamber during the SOFC operation, O2-TPO and SEM analysis were carried out together with the theoretical calculation. Electrochemical tests demonstrated that stable and high power output at an intermediate temperature range was well-maintained with a peak power density of 1061 mW cm(-2) at 750 °C. With the synergic functions provided by the mixed fuel, the SOFC was running for 3 days without any sign of cell performance decay. In sharp contrast, fuelled by pure methane and tested at similar conditions, the SOFC immediately failed after running for only 30 min due to significant carbon deposition. This work opens a new way for SOFC to conquer the annoying problem of carbon deposition just by properly selecting the fuel components to realize their synergic effects. PMID:24856957

  5. Mixed alkali effect on the spectroscopic properties of alkali-alkaline earth oxide borate glasses

    Science.gov (United States)

    Srinivas, G.; Ramesh, B.; Shareefuddin, Md.; Chary, M. N.; Sayanna, R.

    2016-05-01

    The mixed alkali and alkaline earth oxide borate glass with the composition xK2O - (25-x) Li2O-12.5BaO-12.5MgO-50B2O3 (x = 0, 5, 10, 15, 20 and 25mol %) and doped with 1mol% CuO were prepared by the melt quenching technique. From the optical absorption spectra the optical band gap, electronic polarizability(α02-), interaction parameter (A), theoretical and experimental optical basicity (Λ) values were evaluated. From the Electron Paramagnetic Resonance (EPR) spectral data the number of spins (N) and susceptibility (χ) were evaluated. The values of (α02-), and (Λ) increases with increasing of K2O content and electronic polarizability and interaction parameter show opposite behaviuor which may be due to the creation of non-bridging oxygens and expansion of borate network. The reciprocal of susceptibility (1/χ) and spin concentration (N) as a function of K2O content, varied nonlinearly which may be due to creation of non-bridging oxygens in the present glass system. This may be attributed to mixed alkali effect (MAE).

  6. Removal of Hazardous Pollutants from Wastewaters: Applications of TiO2-SiO2 Mixed Oxide Materials

    Directory of Open Access Journals (Sweden)

    Shivatharsiny Rasalingam

    2014-01-01

    Full Text Available The direct release of untreated wastewaters from various industries and households results in the release of toxic pollutants to the aquatic environment. Advanced oxidation processes (AOP have gained wide attention owing to the prospect of complete mineralization of nonbiodegradable organic substances to environmentally innocuous products by chemical oxidation. In particular, heterogeneous photocatalysis has been demonstrated to have tremendous promise in water purification and treatment of several pollutant materials that include naturally occurring toxins, pesticides, and other deleterious contaminants. In this work, we have reviewed the different removal techniques that have been employed for water purification. In particular, the application of TiO2-SiO2 binary mixed oxide materials for wastewater treatment is explained herein, and it is evident from the literature survey that these mixed oxide materials have enhanced abilities to remove a wide variety of pollutants.

  7. Comparison of the redox activities of sol-gel and conventionally prepared Bi-Mo-Ti mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Wildberger, M.; Grundwaldt, J.D.; Mallat, T.; Baiker, A. [Lab. of Technical Chemistry, Swiss Federal Inst. of Technology, ETH-Zentrum, Zuerich (Switzerland)

    1998-12-31

    Novel sol-gel Bi-Mo-Ti oxides have been prepared and characterized by XRD, XPS, FT-Raman and HRTEM. The surface Bi{sup 3+} and Mo{sup 6+} species of some xerogels and an aerogel could be reduced and oxidized at room temperature, whereas the conventionally prepared reference materials were not reduced by H{sub 2} below 300 C. The unusual redox properties, under very mild conditions, are likely due to the unique morphology of Bi-Mo-oxides stabilized by titania. During butadiene oxidation to furan at above 400 C to sol-gel mixed oxides restructured considerably and their performance was barely better than that of titania-supported Bi-Mo oxides. (orig.)

  8. Properties of TiO2-SiO2 Mixed Oxides and Photocatalytic Oxidation of Heptane and Sulfur Dioxide

    Institute of Scientific and Technical Information of China (English)

    XIE Chao; XU Zi-li; YANG Qiu-jing; LI Na; WANG De-bao; DU Yao-guo

    2005-01-01

    A series of TiO2-XSiO2[X denotes the molar fraction(%) of silica in the mixed oxides] with different n(Ti)/n(Si) ratios was prepared with ammonia water as a hydrolysis catalyst. The photocatalysts prepared were characterized by XRD, thermal analysis, FTIR, UV-Vis and SPS. The characterization results of FTIR and UV-Vis spectra show that Ti atoms were gradually changed from octahedral coordination to tetrahedral coordination with the addition of silica, which is not beneficial for obtaining strong Brnsted acidity and higher photocatalytic activity. The photocatalytic activity experiments, which were conducted by using heptane(or SO2) as the model reactant, showed that TiO2-SiO2 containing a suitable amount of silica can exhibit much higher photocatalytic activity than pure TiO2. The enhanced photocatalytic activity can be attributed to three following factors: (1) smaller crystalline size; (2) higher thermal stability; (3) the new strong Brnsted acidity.

  9. Transparent conductive electrodes of mixed TiO2−x–indium tin oxide for organic photovoltaics

    KAUST Repository

    Lee, Kyu-Sung

    2012-05-22

    A transparent conductive electrode of mixed titanium dioxide (TiO2−x)–indium tin oxide (ITO) with an overall reduction in the use of indium metal is demonstrated. When used in organic photovoltaicdevices based on bulk heterojunction photoactive layer of poly (3-hexylthiophene) and [6,6]-phenyl C61 butyric acid methyl ester, a power conversion efficiency of 3.67% was obtained, a value comparable to devices having sputtered ITO electrode. Surface roughness and optical efficiency are improved when using the mixed TiO2−x–ITO electrode. The consumption of less indium allows for lower fabrication cost of such mixed thin filmelectrode.

  10. Effect of Manganese Doping on Oxygen Storage Capacity of Ceria-Zirconia Mixed Oxides

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    CeO2-ZrO2-MnOx mixed oxide series were prepared by sol-gel method. CO pulse and CO-O2 cycle measurements were carried out to examine the oxygen storage complete capacity (OSCC) and dynamic oxygen storage capacity(OSC) of the samples. The doping method brought about strong interactions between manganese oxide and ceria, both in the bulk and on the surface. Only a small part of Mn cations are incorporated into the ceria lattice to form solid solutions and the remaining are left on the surface as finely dispersed Mn3O4. The OSC behaviors of the materials are influenced by the doping amount of Mn and the solubility of Mn in the CeO2 lattice. The OSC is more easily affected by available contents of oxygen storage components when the measurement frequency is low. Comparatively, the concentration of lattice defects, which affects the mobility of bulk oxygen, is the determining factor under high frequency.

  11. Semi-Coke–Supported Mixed Metal Oxides for Hydrogen Sulfide Removal at High Temperatures

    Science.gov (United States)

    Jie, Mi; Yongyan, Zhang; Yongsheng, Zhu; Ting, Guo; Huiling, Fan

    2012-01-01

    Abstract To improve the desulfurization efficiency of sorbents at low cost, modified semi-coke was used as the substrate for mixed metal oxides (ZFM; oxides of zinc [Zn], iron [Fe], and manganese [Mn]) in hot gas desulfurization. Performance of the prepared ZFM/modified semi-coke (MS) sorbents were evaluated in a fixed-bed reactor in the temperature range 400–550°C. Results showed that the molar ratio of Mn to Zn, effect of the substrate, the calcination temperature, and the sulfidation temperature influenced the performance of the sorbents. Optimum conditions for the preparation of the ZFM/MS sorbents were molar ratio of Mn(NO3)2·6H2O, Zn(NO3)2, and Fe(NO3)3, 0.6:1:2; mass ratio of ZFM0.6 to modified semi-coke support, 1:1; and calcination temperature, 600°C. The ZFM0.6/MS sorbent thus prepared exhibited the best sorption sulfur capacity of 27.46% at 450°C. PMID:22783061

  12. Catalytic propane dehydrogenation over In₂O₃–Ga₂O₃ mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Shuai; Gil, Laura Briones; Subramanian, Nachal; Sholl, David S.; Nair, Sankar; Jones, Christopher W.; Moore, Jason S.; Liu, Yujun; Dixit, Ravindra S.; Pendergast, John G. (Dow); (GIT)

    2015-08-26

    We have investigated the catalytic performance of novel In₂O₃–Ga₂O₃ mixed oxides synthesized by the alcoholic-coprecipitation method for propane dehydrogenation (PDH). Reactivity measurements reveal that the activities of In₂O₃–Ga₂O₃ catalysts are 1–3-fold (on an active metal basis) and 12–28-fold (on a surface area basis) higher than an In₂O₃–Al₂O₃ catalyst in terms of C₃H₈ conversion. The structure, composition, and surface properties of the In₂O₃–Ga₂O₃ catalysts are thoroughly characterized. NH₃-TPD shows that the binary oxide system generates more acid sites than the corresponding single-component catalysts. Raman spectroscopy suggests that catalysts that produce coke of a more graphitic nature suppress cracking reactions, leading to higher C₃H₆ selectivity. Lower reaction temperature also leads to higher C₃H₆ selectivity by slowing down the rate of side reactions. XRD, XPS, and XANES measurements, strongly suggest that metallic indium and In₂O₃ clusters are formed on the catalyst surface during the reaction. The agglomeration of In₂O₃ domains and formation of a metallic indium phase are found to be irreversible under O₂ or H₂ treatment conditions used here, and may be responsible for loss of activity with increasing time on stream.

  13. Mg-Fe-mixed oxides derived from layered double hydroxides: A study of the surface properties

    Directory of Open Access Journals (Sweden)

    Marinković-Nedučin Radmila P.

    2011-01-01

    Full Text Available The influence of surface properties on the selectivity of the synthesized catalysts was studied, considering that their selectivity towards particular hydrocarbons is crucial for their overall activity in the chosen Fischer- -Tropsch reaction. Magnesium- and iron-containing layered double hydroxides (LDH, with the general formula: [Mg1-xFex(OH2](CO3x/2?mH2O, x = = n(Fe/(n(Mg+n(Fe, synthesized with different Mg/Fe ratio and their thermally derived mixed oxides were investigated. Magnesium was chosen because of its basic properties, whereas iron was selected due to its well-known high Fischer-Tropsch activity, redox properties and the ability to form specific active sites in the layered LDH structure required for catalytic application. The thermally less stable multiphase system (synthesized outside the optimal single LDH phase range with additional Fe-phase, having a lower content of surface acid and base active sites, a lower surface area and smaller fraction of smaller mesopores, showed higher selectivity in the Fischer-Tropsch reaction. The results of this study imply that the metastability of derived multiphase oxides structure has a greater influence on the formation of specific catalyst surface sites than other investigated surface properties.

  14. Vapor phase hydrogenation of furfural over nickel mixed metal oxide catalysts derived from layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Sulmonetti, Taylor P.; Pang, Simon H.; Claure, Micaela Taborga; Lee, Sungsik; Cullen, David A.; Agrawal, Pradeep K.; Jones, Christopher W.

    2016-05-01

    The hydrogenation of furfural is investigated over various reduced nickel mixed metal oxides derived from layered double hydroxides (LDHs) containing Ni-Mg-Al and Ni-Co-Al. Upon reduction, relatively large Ni(0) domains develop in the Ni-Mg-Al catalysts, whereas in the Ni-Co-Al catalysts smaller metal particles of Ni(0) and Co(0), potentially as alloys, are formed, as evidenced by XAS, XPS, STEM and EELS. All the reduced Ni catalysts display similar selectivities towards major hydrogenation products (furfuryl alcohol and tetrahydrofurfuryl alcohol), though the side products varied with the catalyst composition. The 1.1Ni-0.8Co-Al catalyst showed the greatest activity per titrated site when compared to the other catalysts, with promising activity compared to related catalysts in the literature. The use of base metal catalysts for hydrogenation of furanic compounds may be a promising alternative to the well-studied precious metal catalysts for making biomass-derived chemicals if catalyst selectivity can be improved in future work by alloying or tuning metal-oxide support interactions.

  15. High-temperature X-ray diffraction study of uranium-neptunium mixed oxides

    International Nuclear Information System (INIS)

    Incorporating minor actinides (MAs = Am, Np, Cm) in UO2 fertile blankets is a viable option to recycle them. Despite this applied interest, phase equilibria between uranium and MAs still need to be thoroughly investigated, especially at elevated temperatures. In particular, few reports on the U-Np-O system are available. In the present work, we provide for the first time in situ high-temperature X-ray diffraction results obtained during the oxidation of (U1-yNpy)O2 uranium-neptunium mixed oxides up to 1373 K and discuss subsequent phase transformations. We show that (i) neptunium stabilizes the UO2-type fluorite structure at high temperature and that (ii) the U3O8-type orthorhombic structure is observed in a wide range of compositions. We clearly demonstrate the incorporation of neptunium in this phase, which was a controversial question in previous studies up to now. We believe it is the particular stability of the tetravalent state of neptunium that is responsible for the observed phase relationships. (authors)

  16. Development of a novel wet oxidation process for hazardous and mixed wastes

    International Nuclear Information System (INIS)

    Many DOE waste streams and remediates contain complex and variable mixtures of organic compounds, toxic metals, and radionuclides. These materials are often dispersed in organic or inorganic matrices, such as personal protective equipment, various sludges, soils, and water. The over all objective of the effort described here is to develop a novel catalytic wet oxidation process for the treatment of these multi-component wastes, with the aim of providing a versatile, non-thermal method which will destroy hazardous organic compounds while simultaneously containing and concentrating toxic and radioactive metals for recovery or disposal in a readily stabilized matrix. The DETOX process uses a unique combination of metal catalysts to increase the rate of oxidation of organic materials. The metal catalysts are in the form of salts dissolved in a dilute acid solution. A typical catalyst composition is 60% ferric chloride, 3--4% hydrochloric acid, 0.13% platinum ions, and 0.13% ruthenium ions in a water solution. The catalyst solution is maintained at 423--473 K. Wastes are introduced into contact with the solution, where their organic portion is oxidized to carbon dioxide and water. If the organic portion is chlorinated, hydrogen chloride will be produced as a product. The process is a viable alternative to incineration for the treatment of organic mixed wastes. Estimated costs for waste treatment using the process are from $2.50/kg to $25.00/kg, depending on the size of the unit and the amount of waste processed. Process units can be mobile for on-site treatment of wastes. Results from phase 1 and 2, design and engineering studies, are described

  17. Microbial Ecology Assessment of Mixed Copper Oxide/Sulfide Dump Leach Operation

    Energy Technology Data Exchange (ETDEWEB)

    Bruhn, Debby Fox; Thompson, David Neal; Noah, Karl Scott

    1999-06-01

    Microbial consortia composed of complex mixtures of autotrophic and heterotrophic bacteria are responsible for the dissolution of metals from sulfide minerals. Thus, an efficient copper bioleaching operation depends on the microbial ecology of the system. A microbial ecology study of a mixed oxide/sulfide copper leaching operation was conducted using an "overlay" plating technique to differentiate and identify various bacterial consortium members of the genera Thiobacillus, “Leptospirillum”, “Ferromicrobium”, and Acidiphilium. Two temperatures (30°C and 45°C) were used to select for mesophilic and moderately thermophilic bacteria. Cell numbers varied from 0-106 cells/g dry ore, depending on the sample location and depth. After acid curing for oxide leaching, no viable bacteria were recovered, although inoculation of cells from raffinate re-established a microbial population after three months. Due to low the pH of the operation, very few non-iron-oxidizing acidophilic heterotrophs were recovered. Moderate thermophiles were isolated from the ore samples. Pregnant liquor solutions (PLS) and raffinate both contained a diversity of bacteria. In addition, an intermittently applied waste stream that contained high levels of arsenic and fluoride was tested for toxicity. Twenty vol% waste stream in PLS killed 100% of the cells in 48 hours, indicating substantial toxicity and/or growth inhibition. The data indicate that bacteria populations can recover after acid curing, and that application of the waste stream to the dump should be avoided. Monitoring the microbial ecology of the leaching operation provided significant information that improved copper recovery.

  18. Effect of top gate bias on photocurrent and negative bias illumination stress instability in dual gate amorphous indium-gallium-zinc oxide thin-film transistor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eunji; Chowdhury, Md Delwar Hossain; Park, Min Sang; Jang, Jin, E-mail: jjang@khu.ac.kr [Advanced Display Research Center and Department of Information Display, Kyung Hee University, Seoul 130-701 (Korea, Republic of)

    2015-12-07

    We have studied the effect of top gate bias (V{sub TG}) on the generation of photocurrent and the decay of photocurrent for back channel etched inverted staggered dual gate structure amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film-transistors. Upon 5 min of exposure of 365 nm wavelength and 0.7 mW/cm{sup 2} intensity light with negative bottom gate bias, the maximum photocurrent increases from 3.29 to 322 pA with increasing the V{sub TG} from −15 to +15 V. By changing V{sub TG} from negative to positive, the Fermi level (E{sub F}) shifts toward conduction band edge (E{sub C}), which substantially controls the conversion of neutral vacancy to charged one (V{sub O} → V{sub O}{sup +}/V{sub O}{sup 2+} + e{sup −}/2e{sup −}), peroxide (O{sub 2}{sup 2−}) formation or conversion of ionized interstitial (O{sub i}{sup 2−}) to neutral interstitial (O{sub i}), thus electron concentration at conduction band. With increasing the exposure time, more carriers are generated, and thus, maximum photocurrent increases until being saturated. After negative bias illumination stress, the transfer curve shows −2.7 V shift at V{sub TG} = −15 V, which gradually decreases to −0.42 V shift at V{sub TG} = +15 V. It clearly reveals that the position of electron quasi-Fermi level controls the formation of donor defects (V{sub O}{sup +}/V{sub O}{sup 2+}/O{sub 2}{sup 2−}/O{sub i}) and/or hole trapping in the a-IGZO /interfaces.

  19. Effect of loading content of copper oxides on performance of Mn-Cu mixed oxide catalysts for catalytic combustion of benzene

    Institute of Scientific and Technical Information of China (English)

    CAO Hongyan; LI Xiaoshuang; CHEN Yaoqiang; GONG Maochu; WANG Jianli

    2012-01-01

    A series of Mn-Cu mixed oxide catalysts were prepared by precipitation method.The catalysts were characterized by N2 adsorption-desorption,H2-TPR and XPS.When the loading ratio of manganese oxides to copper oxides was 8:2 or 7:3,the catalysts possessed better catalytic activity,and benzene was converted completely at 558 K.Results of H2-TPR showed that the loading of a small amount of copper oxides decreased the reduction temperature of catalysts.Results of XPS showed that the loading of a small amount of copper oxides increased the proportion of manganese and defective oxygen on the surface of catalysts,and stabilized manganese at higher oxidation state.And the catalyst with the loading ratio 7:3 was a little worse than 8:2,since the interaction between manganese oxides and copper oxides is too strong,copper oxides migrate to the surface of catalysts and manganese oxides in excess are immerged.

  20. Surface structure of crystalline and amorphous chromia catalysts for the selective catalytic reduction of nitric oxide. 2. Diffuse reflectance FTIR study of thermal treatment and oxygen adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Schraml-Marth, M.; Wokaun, A. (Univ. of Bayreuth (Germany)); Curry-Hyde, H.E.; Baiker, A. (Swiss Federal Inst. of Tech., Zuerich (Switzerland))

    1992-02-01

    The activation of crystalline and amorphous chromia surfaces by thermal pretreatment in argon and oxygen adsorption at 473 K has been studied by diffuse reflectance FTIR and Raman spectroscopy. The formation of coordinatively unsaturated chromium sites during thermal activation is monitored by observing the evolution of Cr{double bond}O stretching absorptions both in the fundamental and overtone regions of the FTIR spectrum. On {alpha}-Cr{sub 2}O{sub 3}, labile surface oxygen species are largely removed at 498 K, whereas on the amorphous chromia surface, labile oxygen is more tightly bound. As a consequence, coordinatively unsaturated chromium sites are generated on amorphous chromia to a lesser extent than on {alpha}-Cr{sub 2}O{sub 3}. Upon high-temperature oxygen treatment, O{sub 2} is dissociatively adsorbed. Coordinatively unsaturated sites are occupied by the added oxygen, as manifested by an increase in the number of Cr{double bond}O oscillators. Fine structure in the Cr{double bond}O absorptions of the amorphous chromia is observed for the first time, and is tentatively assigned to various types of surface sites. Raman spectroscopic characterization of the amorphous chromia surface reveals laser-induced dehydration and creation of coordinatively unsaturated surface Cr{double bond}O sites, accompanied by progressive crystallization of the amorphous substrate. Differences between crystalline and amorphous chromia with respect to their SCR activity are correlated with the higher density of labile oxygen species available on the surface of amorphous chromia under SCR reaction conditions (423-473 K).

  1. An assessment of the Thermodynamic Difference Rule for mixed inorganic oxides and comments on the enthalpies of formation of phosphates

    International Nuclear Information System (INIS)

    The applicability of the Thermodynamic Difference Rule to mixed inorganic oxides is assessed for a range of aluminates, borates, ferrites, phosphates, silicates and vanadates. The deviation of the phosphate data from the linear relation between the enthalpy of formation, ΔfH°, of the solid solvating oxide and ΘHf, the Thermodynamic Difference Rule Constant, is discussed and we conclude that the use of ΔfH°(P4O10, s) to provide the solvating oxide data is inappropriate and, instead, a value for ΔfH°(P2O5, s) of −1618 ± 9 kJ mol−1 is proposed

  2. Effect of hydrothermal treatment on catalytic activity of amorphous mesoporous Cr{sub 2}O{sub 3}–ZrO{sub 2} nanomaterials for ethanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoud, Hala R., E-mail: halamahmoud2@yahoo.com

    2015-07-15

    Mesoporous 0.25Cr{sub 2}O{sub 3}–0.75ZrO{sub 2} binary oxide catalysts (CZ-H) with high specific surface areas were successfully synthesized by hydrothermal treatment. The effect of synthesis conditions, such as hydrothermal temperature and time of CZ-H nanomaterials were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopic (EDS), UV–vis diffuse reflectance spectroscopy (DRS) and N{sub 2} adsorption–desorption measurements (BET). The XRD analysis indicated the formation of amorphous materials of binary oxides. The results showed that hydrothermal temperature and time of CZ-H nanomaterials had great influence on the average particle diameter and surface area. Under the optimum synthesis conditions, the best CZ-H nanomaterial synthesized at 210 °C for 3 h (i.e., CZ-H213), presented spherical structure with smallest average particle diameter found to be 1.5 nm and possessed highest surface area of 526.6 m{sup 2}/g. Optical studies by UV–vis spectroscopy for the different CZ-H nanomaterials exhibit slightly blue shift from 3.20 to 3.33 eV due to quantum confined exciton absorption. Moreover, hydrothermal synthesis leads to catalysts with higher surface area and with better acid–base properties than conventional co-precipitation method. Compared to the other nanomaterials, the CZ-H213 catalyst appears to be the best candidate for further application in acid–base catalysis and reusability. - Graphical abstract: Display Omitted - Highlights: • Mesoporous 25%Cr{sub 2}O{sub 3}–75%ZrO{sub 2} catalysts (CZ-H) were prepared by hydrothermal method. • The hydrothermal temperature and time modified the properties of CZ-H nanomaterials. • The best CZ-H nanomaterial synthesized at 210 °C for 3 h (i.e., CZ-H213). • A CZ-H213 nanomaterial had the highest S{sub BET} and smallest average particle diameter. • A mesoporous CZ-H213 used as a reusable active catalyst in the ethanol

  3. Effect of hydrothermal treatment on catalytic activity of amorphous mesoporous Cr2O3–ZrO2 nanomaterials for ethanol oxidation

    International Nuclear Information System (INIS)

    Mesoporous 0.25Cr2O3–0.75ZrO2 binary oxide catalysts (CZ-H) with high specific surface areas were successfully synthesized by hydrothermal treatment. The effect of synthesis conditions, such as hydrothermal temperature and time of CZ-H nanomaterials were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopic (EDS), UV–vis diffuse reflectance spectroscopy (DRS) and N2 adsorption–desorption measurements (BET). The XRD analysis indicated the formation of amorphous materials of binary oxides. The results showed that hydrothermal temperature and time of CZ-H nanomaterials had great influence on the average particle diameter and surface area. Under the optimum synthesis conditions, the best CZ-H nanomaterial synthesized at 210 °C for 3 h (i.e., CZ-H213), presented spherical structure with smallest average particle diameter found to be 1.5 nm and possessed highest surface area of 526.6 m2/g. Optical studies by UV–vis spectroscopy for the different CZ-H nanomaterials exhibit slightly blue shift from 3.20 to 3.33 eV due to quantum confined exciton absorption. Moreover, hydrothermal synthesis leads to catalysts with higher surface area and with better acid–base properties than conventional co-precipitation method. Compared to the other nanomaterials, the CZ-H213 catalyst appears to be the best candidate for further application in acid–base catalysis and reusability. - Graphical abstract: Display Omitted - Highlights: • Mesoporous 25%Cr2O3–75%ZrO2 catalysts (CZ-H) were prepared by hydrothermal method. • The hydrothermal temperature and time modified the properties of CZ-H nanomaterials. • The best CZ-H nanomaterial synthesized at 210 °C for 3 h (i.e., CZ-H213). • A CZ-H213 nanomaterial had the highest SBET and smallest average particle diameter. • A mesoporous CZ-H213 used as a reusable active catalyst in the ethanol conversion

  4. General synthesis of vanadium-based mixed metal oxides hollow nanofibers for high performance lithium-ion batteries

    Science.gov (United States)

    Xiang, Juan; Yu, Xin-Yao; Paik, Ungyu

    2016-10-01

    Hollow nanostructured mixed metal oxides have recently been intensively investigated as electrode materials for energy storage and conversion due to their remarkable electrochemical properties. Although great efforts have been made, the synthesis of hollow nanostructured vanadium-based mixed metal oxides especially those with one dimensional structure is rarely reported. Vanadium-based mixed metal oxides are promising electrode materials for lithium-ion batteries with high capacity and good rate capability. Here, we develop a facile and general method for the synthesis of one dimensional MxV2O8 (M = Co, Ni, Fe) tubular structure through a simple single-spinneret electrospinning technique followed by a calcination process. As a demonstration, Co3V2O8 hollow nanofibers are evaluated as anode materials for lithium-ion batteries. As expected, benefiting from their unique one dimensional tubular structure, the as-synthesized Co3V2O8 exhibits excellent electrochemical properties for lithium storage. To be specific, it can deliver a high specific capacity of 900 mAh g-1 at 5 A g-1, and long cycling stability up to 2000 cycles. The present work makes a significant contribution to the design and synthesis of mixed metal oxides with one dimensional tubular structure, as well as their potential applications in electrochemical energy storage.

  5. Measurement and modelling of the defect chemistry and transport properties of ceramic oxide mixed ionic and electronic conductors

    NARCIS (Netherlands)

    Dalslet, Bjarke Thomas

    2008-01-01

    The mixed ionic and electronic conducting fluorite and perovskite materials examined in this thesis are all oxide ion conducting materials. The defect chemistry and transport properties of a number of these materials are measured using: 1) a measurement technique using an oxygen pump and an electrol

  6. Efficient Removal of Cr(VI with Fe/Mn Mixed Metal Oxide Nanocomposites Synthesized by a Grinding Method

    Directory of Open Access Journals (Sweden)

    Wang Weilong

    2013-01-01

    Full Text Available Fe/Mn mixed metal oxides were synthesized facilely by a grinding method and were characterized by TEM, XRD, XPS, and BET. The characterization results revealed that mixed metal oxides were mainly composed of not highly crystallized Fe2O3 and Mn3O4 nanoparticles with a diameter about 3–5 nm. The specific BET surface areas of the composite were affected by the amounts of KCl diluent in the preparation process and about 268 m2/g of the composite can be achieved. Compared with metal oxide adsorbents existent, the composites showed good adsorption capacity, stability, and regeneration activity for Cr(VI removal. The enhanced adsorption capacity was speculated to be ascribed to the synergistic effect of the mixed metal oxides. By monitoring the valence change in the adsorption process using XPS characterization, the mechanism for Cr(VI removal on the composites was found to be a combination of electrostatic attraction and ion exchange. The above results demonstrated that the synthesized metal oxides nanocomposite is of great potential for Cr(VI removal in the fields of remediation of environmental problems.

  7. Mixed oxide fuels testing in the advanced test reactor to support plutonium disposition

    International Nuclear Information System (INIS)

    An intense worldwide effort is now under way to find means of reducing the stockpile of weapons-grade plutonium. One of the most attractive solutions would be to use WGPu as fuel in existing light water reactors (LWRs) in the form of mixed oxide (MOX) fuel - i.e., plutonia (PUO2) mixed with urania (UO2). Before U.S. reactors could be used for this purpose, their operating licenses would have to be amended. Numerous technical issues must be resolved before LWR operating licenses can be amended to allow the use of MOX fuel. These issues include the following: (1) MOX fuel fabrication process verification, (2) Whether and how to use burnable poisons to depress MOX fuel initial reactivity, which is higher than that of urania, (3) The effects of WGPu isotopic composition, (4) The feasibility of loading MOX fuel with plutonia content up to 7% by weight, (5) The effects of americium and gallium in WGPu, (6) Fission gas release from MOX fuel pellets made from WGPu, (7) Fuel/cladding gap closure, (8) The effects of power cycling and off-normal events on fuel integrity, (9) Development of radial distributions of burnup and fission products, (10) Power spiking near the interfaces of MOX and urania fuel assemblies, and (11) Fuel performance code validation. We have performed calculations to show that the use of hafnium shrouds can produce spectrum adjustments that will bring the flux spectrum in ATR test loops into a good approximation to the spectrum anticipated in a commercial LWR containing MOX fuel while allowing operation of the test fuel assemblies near their optimum values of linear heat generation rate. The ATR would be a nearly ideal test bed for developing data needed to support applications to license LWRs for operation with MOX fuel made from weapons-grade plutonium. The requirements for planning and implementing a test program in the ATR have been identified

  8. Determination of fissile fraction in MOX (mixed U + Pu oxides) fuels for different burnup values

    Energy Technology Data Exchange (ETDEWEB)

    Ozdemir, Levent, E-mail: levent.ozdemir@taek.gov.tr [Department of Nuclear Engineering, Hacettepe University, 06800 Beytepe, Ankara (Turkey); Acar, Banu Bulut; Zabunoglu, Okan H. [Department of Nuclear Engineering, Hacettepe University, 06800 Beytepe, Ankara (Turkey)

    2011-02-15

    When spent Light Water Reactor fuels are processed by the standard Purex method of reprocessing, plutonium (Pu) and uranium (U) in spent fuel are obtained as pure and separate streams. The recovered Pu has a fissile content (consisting of {sup 239}Pu and {sup 241}Pu) greater than 60% typically (although it mainly depends on discharge burnup of spent fuel). The recovered Pu can be recycled as mixed-oxide (MOX) fuel after being blended with a fertile U makeup in a MOX fabrication plant. The burnup that can be obtained from MOX fuel depends on: (1) isotopic composition of Pu, which is closely related to the discharge burnup of spent fuel from which Pu is recovered; (2) the type of fertile U makeup material used (depleted U, natural U, or recovered U); and (3) fraction of makeup material in the mix (blending ratio), which in turn determines the total fissile fraction of MOX. Using the Non-linear Reactivity Model and the code MONTEBURNS, a step-by-step procedure for computing the total fissile content of MOX is introduced. As was intended, the resulting expression is simple enough for quick/hand calculations of total fissile content of MOX required to reach a desired burnup for a given discharge burnup of spent fuel and for a specified fertile U makeup. In any case, due to non-fissile (parasitic) content of recovered Pu, a greater fissile fraction in MOX than that in fresh U is required to obtain the same burnup as can be obtained by the fresh U fuel.

  9. Dual Electrospray Pyrolysis for Mixed Metal Oxide (and Carbon) Composite Nanoparticle Synthesis with Applications in Energy Storage

    Science.gov (United States)

    Tang, Justin; Liu, Wen; Wang, Hailiang; Gomez, Alessandro

    We present a novel approach to synthesizing mixed metal oxide nanoparticles with a continuous, scalable aerosol flow process using the electrospray. The electrospray is a liquid atomization technique that generates a monodisperse population of highly charged liquid droplets over a broad size range (nanometric to tens of microns). Each liquid droplet serves as a micro-reactor, containing a payload of suitable precursors (such as metal nitrides), allowing for precise control over particle composition and size. By using two electrosprays of opposite polarities, the two highly charged droplets plumes are electrostatically mixed to produce a charge-neutral aerosol. Electrostatically driven droplet-droplet collisions can also be used to control morphology to some degree. This aerosol is passed through a tubular furnace via carrier gas, pyrolizing the precursors to synthesize nanomaterials. We apply this approach to manganese oxide, cobalt oxide, and carbon composite nanoparticles for use in energy storage applications.

  10. Conversion of ethanol to 1,3-butadiene over Na doped ZnxZryOz mixed metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Baylon, Rebecca A.; Sun, Junming; Wang, Yong

    2016-01-01

    Despite numerous studies on different oxide catalysts for the ethanol to 1,3-butadiene reaction, few have identified active sites (i.e., type of acidity) correlated to the catalytic performances. In this work, the type of acidity needed for ethanol to 1,3-butadiene conversion has been studied over Zn/Zr mixed oxide catalysts. Specifically, synthesis method, Zn/Zr ratio, and Na doping have been used to control the surface acid-base properties, as confirmed by characterizations such as NH3-TPD and IR-Py techniques. The 2000 ppm Na doped Zn1Zr10Oz-H with balanced base and weak Bronsted acid sites was found to give not only high selectivity to 1,3-butadiene (47%) at near complete ethanol conversion (97%), but also exhibited a much higher 1,3-butadiene productivity than other mixed oxides studied.

  11. Influence of the physico-chemical properties of CeO2-ZrO2 mixed oxides on the catalytic oxidation of NO to NO2

    International Nuclear Information System (INIS)

    Commercial and home-made Ce-Zr catalysts prepared by co-precipitation were characterised by XRD, Raman spectroscopy, N2 adsorption at -196 deg. C and XPS, and were tested for NO oxidation to NO2. Among the different physico-chemical properties characterised, the surface composition seems to be the most relevant one in order to explain the NO oxidation capacity of these Ce-Zr catalysts. As a general trend, Ce-Zr catalysts with a cerium-rich surface, that is, high XPS-measured Ce/Zr atomic surface ratios, are more active than those with a Zr-enriched surface. The decrease in catalytic activity of the Ce-Zr mixed oxided upon calcinations at 800 deg. C with regard to 500 deg. C is mainly attributed to the decrease in Ce/Zr surface ratio, that is, to the surface segregation of Zr. The phase composition (cubic or t'' for Ce-rich compositions) seems not to be a direct effect on the catalytic activity for NO oxidation in the range of compositions tested. However, the formation of a proper solid solution prevents important surface segregation of Zr upon calcinations at high temperature. The effect of the BET surface area in the catalytic activity for NO oxidation of Ce-Zr mixed oxides is minor in comparison with the effect of the Ce/Zr surface ratio.

  12. Phase relations and ionic transport behaviour in new mixed oxides of ceria–zirconia–gadolinia

    Energy Technology Data Exchange (ETDEWEB)

    Anithakumari, P.; Grover, V., E-mail: vinita@barc.gov.in; Tyagi, A.K.

    2015-10-25

    The present study investigates structure and the phase relations observed in complex oxide systems obtained by substituting Gd{sub 2}O{sub 3} in the mixed oxide (Ce{sub 0.8}Zr{sub 0.2})O{sub 2}. The X-ray diffraction studies performed on this system revealed two single-phasic phase-fields; fluorite-type (F-type) and C-type. The transformation from F-type to C-type structure was observed at 60 mol% Gd{sup 3+} substitution. The Raman spectroscopic studies, however, reveal further fine structural insights wherein the F-type region was observed only up to 30 mol% of Gd{sup 3+} which was followed by the co-existence of C-type ordered region and F-type region. The single-phasic C-type phase-field was observed only beyond 80 mol% Gd{sup 3+}-substitution. The AC impedance analysis revealed minimum in the activation energy and maximum in ionic conductivity values as a function of Gd{sup 3+}-content. An antagonistic interplay of activation energy and pre-exponential factor is explained as the major factor behind this behaviour. The determination of migration and association energies supported the trend observed in the ionic conductivity values as a function of Gd{sup 3+}-content. The activation energies for hopping are in good agreement with migration activation energies thus establishing that the conduction mechanism involved hopping of oxygen ions. - Highlights: • Presence of single-phasic F- and C-type phases was revealed by XRD studies. • Both, inter-anionic repulsions and ionic sizes governed the lattice parameters. • C-type micro domains in F-type region and vice versa observed by Raman spectra. • High conductivity of 30% Gd{sup 3+} doped sample agrees with low association energy. • Similar migration and hopping energies reveal the hopping mechanism for conduction.

  13. Phase relations and ionic transport behaviour in new mixed oxides of ceria–zirconia–gadolinia

    International Nuclear Information System (INIS)

    The present study investigates structure and the phase relations observed in complex oxide systems obtained by substituting Gd2O3 in the mixed oxide (Ce0.8Zr0.2)O2. The X-ray diffraction studies performed on this system revealed two single-phasic phase-fields; fluorite-type (F-type) and C-type. The transformation from F-type to C-type structure was observed at 60 mol% Gd3+ substitution. The Raman spectroscopic studies, however, reveal further fine structural insights wherein the F-type region was observed only up to 30 mol% of Gd3+ which was followed by the co-existence of C-type ordered region and F-type region. The single-phasic C-type phase-field was observed only beyond 80 mol% Gd3+-substitution. The AC impedance analysis revealed minimum in the activation energy and maximum in ionic conductivity values as a function of Gd3+-content. An antagonistic interplay of activation energy and pre-exponential factor is explained as the major factor behind this behaviour. The determination of migration and association energies supported the trend observed in the ionic conductivity values as a function of Gd3+-content. The activation energies for hopping are in good agreement with migration activation energies thus establishing that the conduction mechanism involved hopping of oxygen ions. - Highlights: • Presence of single-phasic F- and C-type phases was revealed by XRD studies. • Both, inter-anionic repulsions and ionic sizes governed the lattice parameters. • C-type micro domains in F-type region and vice versa observed by Raman spectra. • High conductivity of 30% Gd3+ doped sample agrees with low association energy. • Similar migration and hopping energies reveal the hopping mechanism for conduction

  14. Method of CO and/or CO.sub.2 hydrogenation using doped mixed-metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Shekhawat, Dushyant; Berry, David A.; Haynes, Daniel J.; Abdelsayed, Victor; Smith, Mark W.; Spivey, James J.

    2015-10-06

    A method of hydrogenation utilizing a reactant gas mixture comprising a carbon oxide and a hydrogen agent, and a hydrogenation catalyst comprising a mixed-metal oxide containing metal sites supported and/or incorporated into the lattice. The mixed-metal oxide comprises a perovskite, a pyrochlore, a fluorite, a brownmillerite, or mixtures thereof doped at the A-site or the B-site. The metal site may comprise a deposited metal, where the deposited metal is a transition metal, an alkali metal, an alkaline earth metal, or mixtures thereof. Contact between the carbon oxide, hydrogen agent, and hydrogenation catalyst under appropriate conditions of temperature, pressure and gas flow rate generate a hydrogenation reaction and produce a hydrogenated product made up of carbon from the carbon oxide and some portion of the hydrogen agent. The carbon oxide may be CO, CO.sub.2, or mixtures thereof and the hydrogen agent may be H.sub.2. In a particular embodiment, the hydrogenated product comprises an alcohol, an olefin, an aldehyde, a ketone, an ester, an oxo-product, or mixtures thereof.

  15. Survey of Worldwide Light Water Reactor Experience with Mixed Uranium-Plutonium Oxide Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Cowell, B.S.; Fisher, S.E.

    1999-02-01

    The US and the Former Soviet Union (FSU) have recently declared quantities of weapons materials, including weapons-grade (WG) plutonium, excess to strategic requirements. One of the leading candidates for the disposition of excess WG plutonium is irradiation in light water reactors (LWRs) as mixed uranium-plutonium oxide (MOX) fuel. A description of the MOX fuel fabrication techniques in worldwide use is presented. A comprehensive examination of the domestic MOX experience in US reactors obtained during the 1960s, 1970s, and early 1980s is also presented. This experience is described by manufacturer and is also categorized by the reactor facility that irradiated the MOX fuel. A limited summary of the international experience with MOX fuels is also presented. A review of MOX fuel and its performance is conducted in view of the special considerations associated with the disposition of WG plutonium. Based on the available information, it appears that adoption of foreign commercial MOX technology from one of the successful MOX fuel vendors will minimize the technical risks to the overall mission. The conclusion is made that the existing MOX fuel experience base suggests that disposition of excess weapons plutonium through irradiation in LWRs is a technically attractive option.

  16. Synthesis, characterization and thermal expansion measurements on uranium-cerium mixed oxides

    Science.gov (United States)

    Venkata Krishnan, R.; Panneerselvam, G.; Singh, Brij Mohan; Kothandaraman, B.; Jogeswararao, G.; Antony, M. P.; Nagarajan, K.

    2011-07-01

    Uranium-cerium mixed oxides (U 1-yCe y)O 2 ( y = 0.2, 0.4, 0.6, 0.8) were prepared by combustion synthesis using citric acid as the fuel. Sintering of the solid solutions was carried out at 1873 K under reduced atmosphere. From the room temperature XRD patterns of the sintered samples it was found that the solid solutions form single phase fluorite structure. The room temperature lattice parameters of (U 1-yCe y)O 2 ( y = 0.2, 0.4, 0.6, 0.8) are 0.5458, 0.5446, 0.5434 and 0.5422 nm respectively. Thermal expansion of (U 1-yCe y)O 2 ( y = 0.2, 0.4, 0.6, 0.8) in the temperature range 298-1973 K was measured by high temperature X-ray diffraction (HTXRD). The coefficients of thermal expansion increase with increase in CeO 2 content in the sample and the measured data in the temperature range 298-1973 K, for (U 1-yCe y)O 2 ( y = 0.2, 0.4, 0.6, 0.8) are 18.23, 19.91, 21.59, 23.29 × 10 -6 K -1, respectively.

  17. Material accountancy system at a new automated mixed-oxide facility: PFPF

    International Nuclear Information System (INIS)

    At conventional mixed-oxide (MOX) fuel fabrication facilities, the personal radiation exposure of operators increases in proportion to the amount of plutonium to be handled. To resolve this issue, automated techniques in high-level radiation areas have been introduced at Japan's new MOX facility, the plutonium fuel production facility (PFPF). The PFPF incorporates a fully automated operating scheme into the main process and storage areas. Unlike conventional MOX fuel fabrication facilities, operators do not need direct access to nuclear material during normal plant operation. To achieve process control including criticality safety, PFPF has introduced an on-line computerized advanced accountancy system (AAS), which is capable of obtaining all inventory information throughout the entire facility in detail. The AAS can acquire material accounting data from equipment installed in each storage unit. All materials in the process areas are itemized as each transfer container is moved, and each container is measured at internal measurement points between a glovebox and any intermediate storage unit. The AAS can acquire material accounting data from information on the amount of nuclear material transferred. Thus, all material accounting data are obtained automatically by management on a real-time basis

  18. Characterization of aerosols from industrial fabrication of mixed-oxide nuclear reactor fuels

    International Nuclear Information System (INIS)

    Recycling plutonium into mixed-oxide (MOX) fuel for nuclear reactors is being given serious consideration as a safe and environmentally sound method of managing plutonium from weapons programs. Planning for the proper design and safe operation of the MOX fuel fabrication facilities can take advantage of studies done in the 1970s, when recycling of plutonium from nuclear fuel was under serious consideration. At that time, it was recognized that the recycle of plutonium and uranium in irradiated fuel could provide a significant energy source and that the use of 239Pu in light water reactor fuel would reduce the requirements for enriched 235U as a reactor fuel. It was also recognized that the fabrication of uranium and plutonium reactor fuels would not be risk-free. Despite engineered safety precautions such as the handling of uranium and plutonium in glove-box enclosures, accidental releases of radioactive aerosols from normal containment might occur. Workers might then be exposed to the released materials by inhalation

  19. Development of an inspection method of plutonium homogeneity in mixed oxide pellets

    International Nuclear Information System (INIS)

    Plutonium homogeneity in mixed oxide pellets is one of the major inspection items. The inspection was carried out by means of a conventional α-autoradiography. It is a technique of detecting α-ray damage on a nitrocellulose film, however, careful operation is required for radiological protection and many of the operation processes. For the sake of easy and efficient operation, a α-ray radiation source photographing device has been developed. The technique consists of the application of scintillation of ZnS(Ag) through α-ray radiation. With this photographing device, plutonium spots as well as uranium spots are clearly photographed from outside the glove box without inserting film therein and without darkening the operation room. This technique makes possible the study of the plutonium homogeneity of pellets for both the FBR and ATR types. In the case a prompt study is necessary, this technique is applicable to green pellets. For the development of this technique, many studies have been made to enable the precise measurement of spot-size plutonium. A brief review of the results are presented in the following. (author)

  20. Decommissioning of a mixed oxide fuel fabrication plant at Winfrith Technolgy Centre

    International Nuclear Information System (INIS)

    The Alpha Materials Laboratory (Building A52) at Winfrith contained a mixed oxide fuel fabrication plant which had a capability of producing 10 te/yr of pelleted/compacted fuel and was in operation from 1962 until 1980, when the requirement for this type of fuel in the UK diminished, and the plant became surplus to requirements. A program to develop decommissioning techniques for plutonium plants was started in 1983, addressing the following aspects of alpha plant decommissioning: (1) Re-usable containment systems, (2) Strippable coating technology, (3) Mobile air filtration plant, (4) Size reduction primarily using cold cutting, (5) techniques, (6) Waste packing, and (7) Alpha plant decommissioning methodology. The technology developed has been used to safely and efficiently decommission radioactive plant and equipment including Pu contaminated glove boxes. (63 glove boxes to date) The technology has been widely adopted in the United Kingdom and elsewhere. This paper outlines the general strategies adopted and techniques used for glove box decommissioning in building A52

  1. Off gas processing device for degreasing furnace for uranium/plutonium mixed oxide fuel

    International Nuclear Information System (INIS)

    A low melting ingredient capturing-cooling trap connected to a degreasing sintering furnace by way of sealed pipelines, a burning/decomposing device for decomposing high melting ingredient gases discharged from the cooling trap by burning them and a gas sucking means for forming the flow of off gases are contained in a glovebox, the inside pressure of which is kept negative. Since the degreasing sintering furnace for uranium/plutonium mixed oxide fuels is disposed outside of the glovebox, operation can be performed safely without greatly increasing the scale of the device, and the back flow of gases is prevented easily by keeping the pressure in the inside of the glovebox negative. Further, a heater is disposed at the midway of the sealed pipelines from the degreasing sintering furnace to the cooling trap, the temperature is kept high to prevent deposition of low melting ingredients to prevent clogging of the sealed pipelines. Further, a portion of the pipelines is made extensible in the axial direction to eliminate thermal stresses caused by temperature change thereby enabling to extend the life of the sealed pipelines. (N.H.)

  2. Romanian irradiation experiment on AHWR type fuel elements containing mixed oxide of thorium and uranium pellets

    International Nuclear Information System (INIS)

    One of the main objectives of the Institute for Nuclear Research (ICN) - Nuclear Fuel R and D Program is the development of new types of fuel based on: Slightly Enriched Uranium (SEU), Recycled Uranium (RU) and Thorium. Two experimental fuel elements (A23 and A24) were irradiated in TRIGA Research Reactor of ICN-Romania (C1 device) in a power ramp conditions. Element A23, contained mixed oxide of thorium and uranium pellets, achieved a maximum linear power of 51 KW/m and has reached a discharge burn-up around 189.2 MWh/KgHE; element A24, contained dioxide of uranium pellets, achieved a maximum linear power of 63 kW/m and has reached a discharge burn-up of around 207.8 MWh/KgHE. The experiments simulation has been performed using an improved version of ROFEM Code, version developed through the efforts of researchers from ICN - Nuclear Fuel Performance Department. The simulation results are in good agreement with experimental data. (author)

  3. Survey of Worldwide Light Water Reactor Experience with Mixed Uranium-Plutonium Oxide Fuel

    International Nuclear Information System (INIS)

    The US and the Former Soviet Union (FSU) have recently declared quantities of weapons materials, including weapons-grade (WG) plutonium, excess to strategic requirements. One of the leading candidates for the disposition of excess WG plutonium is irradiation in light water reactors (LWRs) as mixed uranium-plutonium oxide (MOX) fuel. A description of the MOX fuel fabrication techniques in worldwide use is presented. A comprehensive examination of the domestic MOX experience in US reactors obtained during the 1960s, 1970s, and early 1980s is also presented. This experience is described by manufacturer and is also categorized by the reactor facility that irradiated the MOX fuel. A limited summary of the international experience with MOX fuels is also presented. A review of MOX fuel and its performance is conducted in view of the special considerations associated with the disposition of WG plutonium. Based on the available information, it appears that adoption of foreign commercial MOX technology from one of the successful MOX fuel vendors will minimize the technical risks to the overall mission. The conclusion is made that the existing MOX fuel experience base suggests that disposition of excess weapons plutonium through irradiation in LWRs is a technically attractive option

  4. Synthesis and Characterization of K-Ta Mixed Oxides for Hydrogen Generation in Photocatalysis

    Directory of Open Access Journals (Sweden)

    Beata Zielińska

    2012-01-01

    Full Text Available K-Ta mixed oxides photocatalysts have been prepared by impregnation followed by calcination. The influence of the reaction temperature (450°C–900°C on the phase formation, crystal morphology, and photocatalytic activity in hydrogen generation of the produced materials was investigated. The detailed analysis has revealed that all products exhibit high crystallinity and irregular structure. Moreover, two different crystal structures of potassium tantalates such as KTaO3 and K2Ta4O11 were obtained. It was also found that the sample composed of KTaO3 and traces of unreacted Ta2O5 (annealed at 600°C exhibits the highest activity in the reaction of photocatalytic hydrogen generation. The crystallographic phases, optical and vibronic properties were examined by X-ray diffraction (XRD and diffuse reflectance (DR UV-vis and resonance Raman spectroscopic methods, respectively. Morphology and chemical composition of the produced samples were studied using a high-resolution transmission electron microscope (HR-TEM and an energy dispersive X-ray spectrometer (EDX as its mode.

  5. Mg-Al layered double hydroxides (LDHs) and their derived mixed oxides grown by laser techniques

    Science.gov (United States)

    Matei, A.; Birjega, R.; Nedelcea, A.; Vlad, A.; Colceag, D.; Ionita, M. D.; Luculescu, C.; Dinescu, M.; Zavoianu, R.; Pavel, O. D.

    2011-04-01

    Layered double hydroxides (LDHs) have been widely studied due to their applications as multifunctional materials, catalysts, host materials, anionic exchangers, adsorbents for environmental contaminants and for the immobilization of biological materials. As thin films, LDHs are good candidates for novel applications as sensors, corrosion resistant coatings or components in electro optical devices. For these applications, lamellar orientation-controlled film has to be fabricated. In this work, the successful deposition of LDH and their derived mixed oxides thin films by laser techniques is reported. Pulsed laser deposition (PLD) and matrix assisted pulsed laser evaporation (MAPLE) were the methods used for thin films deposition. The ability of Mg-Al LDHs as a carrier for metallic particles (Ag) has been considered. Frozen targets containing 10% powder in water were used for MAPLE, while for PLD the targets consisted in dry-pressed pellets. The structure and the surface morphology of the deposited films were examined by X-ray Diffraction, Atomic Force Microscopy, Scanning Electron Microscopy and Secondary Ion Mass Spectrometry.

  6. The development of a package for the transport of new mixed oxide fuel assemblies within Europe

    International Nuclear Information System (INIS)

    The use of mixed oxide (MOX) fuels in commercial reactors has increased significantly over the past 10 years as an effective way of using stocks of plutonium produced from reprocessing uranium fuels. Now, with advances in fuel design MOX can give performance approaching that of enriched uranium fuel. To meet demand from European and Japanese utilities, British Nuclear Fuels are currently building a large scale plant at Sellafield to assemble MOX fuels. This required a new transport package to be developed capable of carrying high specification fuels to customers in Europe whilst complying with the latest 1996 IAEA ST-1 Transport Regulations. This package is known as Euromox and currently under development to enter service in 2003. Relatively few packages exist for the transport of MOX fuels and Euromox is the first designed by BNFL for shipments to Europe. Euromox has provided several technical challenges in its development arguably exceeding those typically encountered during the development of new packages for irradiated fuel transports. (author)

  7. Synthesis and characterization of Tin / Titanium mixed oxide nanoparticles doped with lanthanide for biomarking

    International Nuclear Information System (INIS)

    This work presents the synthesis, characterization and photo luminescent study of tin and titanium mixed oxide nanoparticles doped with europium, terbium and neodymium to be used with luminescent markers on biological systems. The syntheses were done by co-precipitation, protein sol-gel and Pechini methods and the nanoparticles were characterized by infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, X-ray diffraction and X-ray absorption spectroscopy. The photo luminescent properties studies were conducted for luminophores doped with europium, terbium and neodymium synthesized by coprecipitation method. For luminophore doped with europium it was possible to calculate the intensity parameters and quantum yield and it showed satisfactory results. In the case of biological system marking it was necessary the functionalization of these particles to allow them to bind to the biological part to be studied. So the nanoparticles were functionalized by microwave and Stöber methods and characterized by infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction obtaining qualitative response of functionalization efficacy. The ninhydrin spectroscopic method was used for quantification of luminophores functionalization. The photo luminescent studies of functionalized particles demonstrate the potential applying of these luminophores as luminescent markers. (author)

  8. Post irradiation examination of thoria-plutonia mixed oxide fuel in Indian hot cells

    International Nuclear Information System (INIS)

    Mixed oxide (MOX) fuel clusters containing ThO2+4%PuO2, and ThO2+6.75%PuO2 fuel pins were irradiated in the pressurized water loop of the Indian research reactor CIRUS, to burn up in the range of 20 GWd/T(HM). The ThO2+4%PuO2 fuel elements had free standing cladding made of Zircaloy-2 and the ThO2+6.75%PuO2 had collapsible Zircaloy-2 cladding. The fuel clusters had performed well during irradiation with no apparent indications of failure. The techniques used for the post irradiation examination (PIE) of these fuels in the hot cells included visual examination, fuel pin diameter measurements, leak testing, gamma scanning, gamma spectrometry, ultrasonic testing, eddy current testing, ceramography, metallography, beta gamma autoradiography and measurement of released fission gases. Micro hardness measurement of cladding and evaluation of mechanical properties using ring tension test were also carried out. This paper elaborates on the techniques and the results of the PIE carried out on ThO2+4%PuO2 fuel. (author)

  9. An experimental study of grain growth in mixed oxide samples with various microstructures and plutonium concentrations

    International Nuclear Information System (INIS)

    Samples of (U, Pu)O2 Mixed Oxide (MOX) with various microstructure and plutonium contents ranging between 4% and 25% have been submitted to a series of heat treatments in order to assess grain growth between 1350 and 1750 °C. XRD measurements on the samples indicated that they were not affected by modifications in the oxygen-to-metal ratio during annealing. The grain size distributions inferred by means of image analysis of metallographic pictures reveal that, when taking into account the experimental uncertainties, the grain growth kinetics are similar to those observed in conventional UO2 fuel that was also tested under the same conditions. An analysis of experimental data available in the open literature for both UO2 and MOX fuel leads to the same conclusion. It is therefore suggested that grain growth models for UO2 fuel can be applied to MOX fuel for fuel performance simulations, when taking into consideration the uncertainties pertaining to grain growth measurements

  10. Quantification of plutonium heterogeneity in (U, Pu) mixed oxide fuel using Passive Gamma Scanning

    International Nuclear Information System (INIS)

    Highlights: ► Analysis of passive gamma scans of MOX fuel. ► Quantitative estimation of plutonium rich agglomerates. ► Use of through well geometry for Passive Gamma Scanning. -- Abstract: During the fabrication of (U, Pu)O2 mixed oxide (MOX) fuel for the Prototype Fast Breeder Reactor (PFBR), which is being built at Kalppakkam, India, it was necessary to achieve homogeneous distribution of plutonium in UO2 matrix for good thermo mechanical behavior of the fuel in reactor as well as for better solubility of the spent fuel during reprocessing. Since the conventional techniques used for estimating plutonium homogeneity in MOX are destructive in nature, they can be performed only on representative samples. The reliability of these techniques is less in large scale MOX fabrication facilities where MOX blends are prepared in large quantity. Passive Gamma Scanning of the fuel pin is carried out as a quality control check for PuO2 content in MOX fuel pin for PFBR. A new methodology has been developed in analyzing the Passive gamma scans to estimate the heterogeneity of plutonium distribution in MOX fuel pins for PFBR

  11. Advanced oxidation and reduction processes: Closed-loop applications for mixed waste

    International Nuclear Information System (INIS)

    At Los Alamos we are engaged in applying innovative oxidation and reduction technologies to the destruction of hazardous organics. Non thermal plasmas and relativistic electron-beams both involve the generation of free radicals and are applicable to a wide variety of mixed waste as closed-loop designs can be easily engineered. Silent discharge plasmas (SDP), long used for the generation of ozone, have been demonstrated in the laboratory to be effective in destroying hazardous organic compounds and offer an altemative to existing post-incineration and off-gas treatments. SDP generates very energetic electrons which efficiently create reactive free radicals, without adding the enthalpy associated with very high gas temperatures. A SDP cell has been used as a second stage to a LANL designed, packed-bed reactor (PBR) and has demonstrated DREs as high as 99.9999% for a variety of combustible liquid and gas-based waste streams containing scintillation fluids, nitrates, PCB surrogates, and both chlorinated and fluorinated solvents. Radiolytic treatment of waste using electron-beams and/or bremsstrahlung can be applied to a wide range of waste media (liquids, sludges, and solids). The efficacy and economy of these systems has been demonstrated for aqueous waste through both laboratory and pilot scale studies. We win present recent experimental and theoretical results for systems using stand alone SDP, combined PBR/SDP, and electron-beam treatment methods

  12. Melting behavior of (Th,U)O2 and (Th,Pu)O2 mixed oxides

    Science.gov (United States)

    Ghosh, P. S.; Kuganathan, N.; Galvin, C. O. T.; Arya, A.; Dey, G. K.; Dutta, B. K.; Grimes, R. W.

    2016-10-01

    The melting behaviors of pure ThO2, UO2 and PuO2 as well as (Th,U)O2 and (Th,Pu)O2 mixed oxides (MOX) have been studied using molecular dynamics (MD) simulations. The MD calculated melting temperatures (MT) of ThO2, UO2 and PuO2 using two-phase simulations, lie between 3650-3675 K, 3050-3075 K and 2800-2825 K, respectively, which match well with experiments. Variation of enthalpy increments and density with temperature, for solid and liquid phases of ThO2, PuO2 as well as the ThO2 rich part of (Th,U)O2 and (Th,Pu)O2 MOX are also reported. The MD calculated MT of (Th,U)O2 and (Th,Pu)O2 MOX show good agreement with the ideal solidus line in the high thoria section of the phase diagram, and evidence for a minima is identified around 5 atom% of ThO2 in the phase diagram of (Th,Pu)O2 MOX.

  13. Iron - based bulk amorphous alloys

    Directory of Open Access Journals (Sweden)

    R. Babilas

    2010-07-01

    Full Text Available Purpose: The paper presents a structure characterization, thermal and soft magnetic properties analysis of Fe-based bulk amorphous materials in as-cast state and after crystallization process. In addition, the paper gives some brief review about achieving, formation and structure of bulk metallic glasses as a special group of amorphous materials.Design/methodology/approach: The studies were performed on Fe72B20Si4Nb4 metallic glass in form of ribbons and rods. The amorphous structure of tested samples was examined by X-ray diffraction (XRD, transmission electron microscopy (TEM and scanning electron microscopy (SEM methods. The thermal properties of the glassy samples were measured using differential thermal analysis (DTA and differential scanning calorimetry (DSC. The magnetic properties contained initial and maximum magnetic permeability, coercive force and magnetic after-effects measurements were determined by the Maxwell-Wien bridge and VSM methods.Findings: The X-ray diffraction and transmission electron microscopy investigations revealed that the studied as-cast bulk metallic glasses in form of ribbons and rods were amorphous. Two stage crystallization process was observed for studied bulk amorphous alloy. The differences of crystallization temperature between ribbons and rods with chosen thickness are probably caused by different amorphous structures as a result of the different cooling rates in casting process. The SEM images showed that studied fractures could be classified as mixed fractures with indicated two zones contained “river” and “smooth” areas. The changing of chosen soft magnetic properties (μr, Bs, Hc obtained for samples with different thickness is a result of the non-homogenous amorphous structure of tested metallic glasses. The annealing process in temperature range from 373 to 773 K causes structural relaxation of tested amorphous materials, which leads to changes in their physical properties. The qualitative

  14. Room-temperature oxidation of hypostoichiometric uranium-plutonium mixed oxides U1-yPuyO2-x - A depth-selective approach

    Science.gov (United States)

    Vauchy, Romain; Robisson, Anne-Charlotte; Belin, Renaud C.; Martin, Philippe M.; Scheinost, Andreas C.; Hodaj, Fiqiri

    2015-10-01

    In the present work, TGA, XAS and XRD were used to evidence the spontaneous oxidation of biphasic U1-yPuyO2-x samples, with y = 0.28 and 0.45, at room temperature and upon exposure to low moisture and oxygen contents. The oxidation occurs within very short timescales (e.g. O/M ratio increasing from 1.94 to 1.98 within ∼1 μm surface layer in ∼50 h). The combined use of these three complementary methods offered a depth-selective approach from the sample's bulk to its surface and allowed a thorough understanding of the underlying processes involved during the formation of the oxidized layer and of its thickening with time. We believe our results to be of interest in the prospect of fabricating hypo-stoichiometric uranium-plutonium mixed oxides since mastering the oxygen content is a crucial point for many of the fuel properties.

  15. Mixed oxides fuels. Adaptation of PWR core and vessel to the mixed oxides fuels. The physical aspect in the conception of the plutonium assemblies

    International Nuclear Information System (INIS)

    The use of mixed plutonium oxyde fuels (Mox) does not create a prejudice on the performances, manoeuvrability and flexibility of the reactor operation. In this paper, the authors recall the neutronic differences between the plutonium and the uranium and indicate the realized experiences made for qualifying the Mox fuel

  16. Remarkable changes in interface O vacancy and metal-oxide bonds in amorphous indium-gallium-zinc-oxide thin-film transistors by long time annealing at 250 °C

    International Nuclear Information System (INIS)

    We have studied the effect of long time post-fabrication annealing on negative bias illumination stress (NBIS) of amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film-transistors. Annealing for 100 h at 250 °C increased the field effect mobility from 14.7 cm2/V s to 17.9 cm2/V s and reduced the NBIS instability remarkably. Using X-ray photoelectron spectroscopy, the oxygen vacancy and OH were found to exist at the interfaces of a-IGZO with top and bottom SiO2. Long time annealing helps to decrease the vacancy concentration and increase the metal-oxygen bonds at the interfaces; this leads to increase in the free carrier concentrations in a-IGZO and field-effect mobility. X-ray reflectivity measurement indicated the increment of a-IGZO film density of 5.63 g cm−3 to 5.83 g cm−3 (3.4% increase) by 100 h annealing at 250 °C. The increase in film density reveals the decrease of O vacancy concentration and reduction of weak metal-oxygen bonds in a-IGZO, which substantially helps to improve the NBIS stability

  17. Preparation of Nanocrystalline Rare Earth Mixed Oxides DyFexCo1-xO3-δ and Its Conductivity

    Institute of Scientific and Technical Information of China (English)

    任引哲; 王建英; 刘二保

    2002-01-01

    Nanocrystalline rare earth mixed oxides DyFexCo1-xO3-δ were prepared by sol-gel method and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG-DTA) and scanning electron microscope (SEM). The results show that DyFexCo1-xO3-δ has the structure of perovskite type at 800 ℃ for 2 h calcination. The conductivity of the materials at different temperature was measured by four-probe instrumentation and two-pole method. The results show that the conductivity of mixed oxides DyFexCo1-xO3-δ is higher than those of un-mixed oxides DyFeO3 and DyCoO3 and the conductivity is the best at x=0.8 in the matter of DyFexCo1-xO3-δ. The conductivity of these materials always increases with the temperature rising and there is an apparent change between 600 and 800 ℃. However, the spinodals are different with different ration of Fe3+ and Co3+. This kind of oxide is a conductive pottery material.

  18. Synthesis of Mixed Cu/Ce Oxide Nanoparticles by the Oil-in-Water Microemulsion Reaction Method

    Directory of Open Access Journals (Sweden)

    Kelly Pemartin-Biernath

    2016-06-01

    Full Text Available Cerium oxide and mixed Cu/Ce oxide nanoparticles were prepared by the oil-in-water (O/W microemulsion reaction method in mild conditions. The Cu/Ce molar ratio was varied between 0/100 and 50/50. According to X-ray diffraction (XRD, below 30/70 Cu/Ce molar ratio, the materials presented a single phase consistent with cubic fluorite CeO2. However, above Cu/Ce molar ratio 30/70, an excess monoclinic CuO phase in coexistence with the predominant Cu/Ce mixed oxide was detected by XRD and High-Resolution Transmission Electron Microscopy (HRTEM. Raman spectroscopy showed that oxygen vacancies increased significantly as the Cu content was increased. Band gap (Eg was investigated as a function of the Cu/Ce molar ratio, resulting in values from 2.91 eV for CeO2 to 2.32 eV for the mixed oxide with 30/70 Cu/Ce molar ratio. These results indicate that below 30/70 Cu/Ce molar ratio, Cu2+ is at least partially incorporated into the ceria lattice and very well dispersed in general. In addition, the photodegradation of Indigo Carmine dye under visible light irradiation was explored for selected samples; it was shown that these materials can remove such contaminants, either by adsorption and/or photodegradation. The results obtained will encourage investigation into the optical and photocatalytic properties of these mixed oxides, for widening their potential applications.

  19. Direct observation of nanometer-scale amorphous layers and oxide crystallites at grain boundaries in polycrystalline Sr1−xKxFe2As2 superconductors

    KAUST Repository

    Wang, Lei

    2011-06-01

    We report here an atomic resolution study of the structure and composition of the grain boundaries in polycrystallineSr0.6K0.4Fe2As2superconductor. A large fraction of grain boundaries contain amorphous layers larger than the coherence length, while some others contain nanometer-scale crystallites sandwiched in between amorphous layers. We also find that there is significant oxygen enrichment at the grain boundaries. Such results explain the relatively low transport critical current density (Jc) of polycrystalline samples with respect to that of bicrystal films.

  20. Ceria-Based Mixed Oxide Supported Nano-Gold as an Efficient and Durable Heterogeneous Catalyst for Oxidative Dehydrogenation of Amines to Imines Using Molecular Oxygen

    Directory of Open Access Journals (Sweden)

    Bashir Ahmad Dar

    2012-06-01

    Full Text Available The present work is intended to determine the catalytic activity of Mixed Oxide supported gold for aerobic oxidative dehydrogenation of amines to imines using Ceria as a main constituent of the each support. The model catalysts Au/CeO2:TiO2 Au/CeO2:SiO2, Au/CeO2:ZrO2 and Au/CeO2:Al2Os were prepared by deposition co-precipitation method and deposition of gold was determined by EDEX analysis. The supported nano-gold catalyzes the dehydrogenation of secondary amines to imines without loss of activity. On recycling good amount of product yield is obtained. Oxidation of secondary amines to imines is carried at 100˚C and almost 90 % conversion was obtained with >99% selectivity. © 2012 BCREC UNDIP. All rights reservedReceived: 26th December 2011; Revised: 7th June 2012; Accepted: 13rd June 2012[How to Cite: B.A. Dar, M. Sharma, B. Singh. (2012. Ceria-Based Mixed Oxide Supported Nano-Gold as an Efficient and Durable Heterogeneous Catalyst for Oxidative Dehydrogenation of Amines to Imines Using Molecular Oxygen. Bulletin of Chemical Reaction Engineering & Catalysis, 7(1: 79-84.  doi:10.9767/bcrec.7.1.1257.79-84][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1257.79-84 ] | View in 

  1. Oxidative stabilization of mixed mayonnaises made with linseed oil and saturated medium-chain triglyceride oil

    NARCIS (Netherlands)

    Raudsepp, P.; Brüggemann, D.A.; Lenferink, A.T.M.; Otto, C.; Andersen, M.L.

    2014-01-01

    Mayonnaises, made with either saturated medium chain triglyceride (MCT) oil or unsaturated purified linseed oil (LSO), were mixed. Raman confocal microspectrometry demonstrated that lipid droplets in mixed mayonnaise remained intact containing either MCT oil or LSO. Peroxide formation during storage

  2. Synthesis and characterization of composites of mixed oxides of iron and neodymium in polymer matrix of aniline–formaldehyde

    Indian Academy of Sciences (India)

    Sajdha; H N Sheikh; B L Kalsotra; N Kumar; S Kumar

    2011-07-01

    Nanocomposites of mixed oxides of iron and neodymium in polymer matrix of anilineformaldehyde are reported. The composites have been obtained by treating the aqueous solution of aniline, hydrochloric acid and formaldehyde with halide of iron and neodymium oxide. The infra-red spectra show broad peaks at ∼ 590 cm-1 and at ∼ 610 cm-1 due to the presence of oxides of both iron and neodymium. In heated samples, the absorption peaks due to metal oxides are better resolved. A broad and strong peak in XRD spectra at 2 value of 35.69920 corresponds to spinel -Fe2O3. 57Fe Mössbauer spectrum for unheated sample gives Mössbauer parameters, i.e. isomer shift (), quadrupole splitting ( ) and effective magnetic field (Heff). Transmission electron microscopy (TEM) micrographs reveal well dispersed particles at different magnifications. Vibrating sample magnetometry (VSM) studies indicate that the ferrite nanoparticles exhibit characteristics of ferromagnetism.

  3. Surface Reduction of Neptunium Dioxide and Uranium Mixed Oxides with Plutonium and Thorium by Photocatalytic Reaction with Ice

    OpenAIRE

    CAKIR PELIN; ELOIRDI Rachel; Huber, Frank; KONINGS Rudy; GOUDER Thomas

    2014-01-01

    The surface reductions of neptunium dioxide (NpO2) and two mixed oxides of uranium (U−Pu−O2 and U−Th−O2) with adsorbed water ice were studied by ultraviolet and X-ray photoelectron spectroscopy (UPS and XPS, respectively). The oxides were produced as thin films by reactive sputter deposition. Water was condensed as a thick ice overlayer on the surface at low temperature. Subsequent warming led to desorption of the ice. When warmed up under ultraviolet light (UV light, HeI and HeII radiatio...

  4. A small-angle neutron scattering study of sodium dodecyl sulfate-poly(propylene oxide) methacrylate mixed micelles.

    Science.gov (United States)

    Bastiat, Guillaume; Grassl, Bruno; Borisov, Oleg; Lapp, Alain; François, Jeanne

    2006-03-15

    Mixed micelle of protonated or deuterated sodium dodecyl sulfate (SDS and SDSd25, respectively) and poly(propylene oxide) methacrylate (PPOMA) are studied by small-angle neutron scattering (SANS). In all the cases the scattering curves exhibit a peak whose position changes with the composition of the system. The main parameters which characterize mixed micelles, i.e., aggregation numbers of SDS and PPOMA, geometrical dimensions of the micelles and degree of ionisation are evaluated from the analysis of the SANS curves. The position q(max) of the correlation peak can be related to the average aggregation numbers of SDS-PPOMA and SDSd25-PPOMA mixed micelles. It is found that the aggregation number of SDS decreases upon increasing the weight ratio PPOMA/SDS (or SDSd25). The isotopic combination, which uses the "contrast effect" between the two micellar systems, has allowed us to determine the mixed micelle composition. Finally, the SANS curves were adjusted using the RMSA for the structure factor S(q) of charged spherical particles and the form factor P(q) of spherical core-shell particle. This analysis confirms the particular core-shell structure of the SDS-PPOMA mixed micelle, i.e., a SDS "core" micelle surrounded by the shell formed by PPOMA macromonomers. The structural parameters of mixed micelles obtained from the analysis of the SANS data are in good agreement with those determined previously by conductimetry and fluorescence studies.

  5. Neutron Emission Characteristics of Two Mixed-Oxide Fuels: Simulations and Initial Experiments

    Energy Technology Data Exchange (ETDEWEB)

    D. L. Chichester; S. A. Pozzi; J. L. Dolan; M. Flaska; J. T. Johnson; E. H. Seabury; E. M. Gantz

    2009-07-01

    Simulations and experiments have been carried out to investigate the neutron emission characteristics of two mixed-oxide (MOX) fuels at Idaho National Laboratory (INL). These activities are part of a project studying advanced instrumentation techniques in support of the U.S. Department of Energy's Fuel Cycle Research and Development program and it's Materials Protection, Accounting, and Control for Transmutation (MPACT) campaign. This analysis used the MCNP-PoliMi Monte Carlo simulation tool to determine the relative strength and energy spectra of the different neutron source terms within these fuels, and then used this data to simulate the detection and measurement of these emissions using an array of liquid scintillator neutron spectrometers. These calculations accounted for neutrons generated from the spontaneous fission of the actinides in the MOX fuel as well as neutrons created via (alpha,n) reactions with oxygen in the MOX fuel. The analysis was carried out to allow for characterization of both neutron energy as well as neutron coincidences between multiple detectors. Coincidences between prompt gamma rays and neutrons were also analyzed. Experiments were performed at INL with the same materials used in the simulations to benchmark and begin validation tests of the simulations. Data was collected in these experiments using an array of four liquid scintillators and a high-speed waveform digitizer. Advanced digital pulse-shape discrimination algorithms were developed and used to collect this data. Results of the simulation and modeling studies are presented together with preliminary results from the experimental campaign.

  6. Americium characterization by X-ray fluorescence and absorption spectroscopy in plutonium uranium mixed oxide

    International Nuclear Information System (INIS)

    Plutonium uranium mixed oxide (MOX) fuels are currently used in nuclear reactors. The actinides in these fuels need to be analyzed after irradiation for assessing their behaviour with regard to their environment and the coolant. In this work the study of the atomic structure and next-neighbour environment of Am in the (Pu,U)O2 lattice in an irradiated (60 MW d kg−1) MOX sample was performed employing micro-X-ray fluorescence (µ-XRF) and micro-X-ray absorption fine structure (µ-XAFS) spectroscopy. The chemical bonds, valences and stoichiometry of Am (∼0.66 wt%) are determined from the experimental data gained for the irradiated fuel material examined in its peripheral zone (rim) of the fuel. In the irradiated sample Am builds up as Am3+ species within an [AmO8]13− coordination environment (e.g. >90%) and no (III XAFS spectra recorded for the irradiated MOX sub-sample in the rim zone for a 300 μm×300 μm beam size area investigated over six scans of 4 h. The records remain constant during multi-scan. The analysis of the XAFS signal shows that Am is found as trivalent in the UO2 matrix. This analytical work shall open the door of very challenging analysis (speciation of fission product and actinides) in irradiated nuclear fuels. - Highlights: • Americium was characterized by microX-ray absorption spectroscopy in irradiated MOX fuel. • The americium redox state as determined from XAS data of irradiated fuel material was Am(III). • In the sample, the Am3+ face an AmO813− coordination environment in the (Pu,U)O2 matrix. • The americium dioxide is reduced by the uranium dioxide matrix

  7. Influence of nutrients on oxidation of low level methane by mixed methanotrophic consortia.

    Science.gov (United States)

    Karthikeyan, Obulisamy Parthiba; Chidambarampadmavathy, Karthigeyan; Nadarajan, Saravanan; Heimann, Kirsten

    2016-03-01

    Low-level methane emissions from coal mine ventilation air (CMV-CH4; i.e., 1 % CH4) can significantly contribute to global climate change, and therefore, treatment is important to reduce impacts. To investigate CMV-CH4 abatement potential, five different mixed methanotrohic consortia (MMCs) were established from soil/sediment sources, i.e., landfill top cover soil, bio-solid compost, vegetated humus soil, estuarine and marine sediments. Enrichment conditions for MMCs were as follows: nitrate mineral salt (NMS) medium, pH ~ 6.8; 25 °C; 20-25 % CH4; agitation 200 rpm; and culture period 20 days, in mini-bench-top bioreactors. The enriched cultures were supplemented with extra carbon (methanol 0.5-1.5 %, formate 5-15 mM, and acetate 5-15 mM), nitrogen (nitrate 0.5-1.5 g L(-1), ammonium 0.1-0.5 g L(-1), or urea: 0.1-0.5 g L(-1)), and trace elements (copper 1-5 μM, iron 1-5 μM, and zinc 1-5 μM) in different batch experiments to improve low-level CH4 abatement. Average CH4 oxidation capacities (MOCs) of MMCs varied between 1.712 ± 0.032 and 1.963 ± 0.057 mg g(-1)DWbiomass h(-1). Addition of formate improved the MOCs of MMCs, but the dose-response varied for different MMCs. Acetate, nitrate and copper had no significant effect on MOCs, while addition of methanol, ammonium, urea, iron and zinc impacted negatively. Overall, MMCs enriched from marine sediments and landfill top cover soil showed high MOCs which were largely resilient to nutrient supplementation, suggesting a strong potential for biofilter development for industrial low-level CH4 abatement, such as those present in CMV. PMID:26867685

  8. Use of Raman spectroscopy to assess the efficiency of MgAl mixed oxides in removing cyanide from aqueous solutions

    Science.gov (United States)

    Cosano, Daniel; Esquinas, Carlos; Jiménez-Sanchidrián, César; Ruiz, José Rafael

    2016-02-01

    Calcining magnesium/aluminium layered double hydroxides (Mg/Al LDHs) at 450 °C provides excellent sorbents for removing cyanide from aqueous solutions. The process is based on the "memory effect" of LDHs; thus, rehydrating a calcined LDH in an aqueous solution restores its initial structure. The process, which conforms to a first-order kinetics, was examined by Raman spectroscopy. The metal ratio of the LDH was found to have a crucial influence on the adsorption capacity of the resulting mixed oxide. In this work, Raman spectroscopy was for the first time use to monitor the adsorption process. Based on the results, this technique is an effective, expeditious choice for the intended purpose and affords in situ monitoring of the adsorption process. The target solids were characterized by using various instrumental techniques including X-ray diffraction spectroscopy, which confirmed the layered structure of the LDHs and the periclase-like structure of the mixed oxides obtained by calcination.

  9. Measurement of isoprene and its oxidation products in a mixed deciduous forest - first results of the ECHO-campaign

    Science.gov (United States)

    Schaub, A.; Komenda, M.; Koppmann, R.

    2003-04-01

    Biogenic hydrocarbons contribute significantly to the budget of reactive trace gases in the atmosphere. Isoprene which is emitted from almost every plant is the most abundant of the biogenic VOC. Most of the ambient measurements of isoprene and its oxidation products methacrolein (MACR) and methyl vinyl ketone (MVK) have been carried out only for short periods of several days to weeks. Therefore, the knowledge of long term changes in isoprene emission and photooxidation are scarce. One objective of the ECHO-project (Emission and Chemical transformation of biogenic volatile organic compounds) is to investigate the isoprene chemistry in a mixed deciduous forest and the exchange processes between the forest and the PBL. Here we describe measurements of isoprene and its oxidation products measured with an online GC-FID system between June and November 2002 in a mixed beech oak forest. The results show a diurnal cycle of isoprene mixing ratios being dependent on temperature and light intensity. The mixing ratios were in the range of 0.02 - 3 ppb with a mean daytime maximum of 500 ppt. In October the daytime isoprene mixing ratio decreased to 50 ppt indicating senescence of leaves. For MVK and MACR a diurnal cycle was found with mean daytime maximum values of 60 ppt and 80 ppt, respectively. In June and July 2002 the maximum daytime ratio between MVK and MACR was < 1, in August this ratio increased to 1.6. This surprising result, which pointed towards a strong influence of NOx on the isoprene oxidation pathways, was further investigated in simulation experiments (see contribution by Komenda et al) and model studies (see contribution by Karl and Dorn).

  10. Electrochemical properties of mixed conducting (La,M)(CoFe) oxide perovskites (M=3DSr, Ca, and Ba)

    Energy Technology Data Exchange (ETDEWEB)

    Stevenson, J.W.; Armstrong, T.R.; Bates, J.L. [and others

    1996-04-01

    Electrical properties and oxygen permeation properties of solid mixed-conducting electrolytes (La,M)(CoFe) oxide perovskites (M=3DSr, Ca, and Ba) have been characterized. These materials are potentially useful as passive membranes to separate high purity oxygen from air and as the cathode in a fuel cell. Dilatometric linear expansion measurements were performed as a function of temperature and oxygen partial pressure to evaluate the stability.

  11. Oxygen surface exchange kinetics of SrTi1-xFexO3-d mixed conducting oxides

    NARCIS (Netherlands)

    Yoo, C.-Y.; Bouwmeester, H.J.M.

    2012-01-01

    The oxygen surface exchange kinetics of mixed conducting perovskite oxides SrTi1−xFexO3−δ (x = 0, 0.01, 0.05, 0.35, 0.5) has been investigated as a function of temperature and oxygen partial pressure using the pulse-response 18O–16O isotope exchange (PIE) technique. Arrhenius activation energies ran

  12. Measurement and modelling of the defect chemistry and transport properties of ceramic oxide mixed ionic and electronic conductors

    DEFF Research Database (Denmark)

    Dalslet, Bjarke Thomas

    2008-01-01

    The subject of this thesis is ceramic mixed ionic and electronic conductors (MIECs). MIECs have potential uses, such as solid oxygen permeation membranes, as catalysts, and as components in fuel cells. The MIECs examined in this thesis are all oxide ion conducting materials. This thesis describes...... the defect chemistry and transport properties of a number of MIECs, and the measurement methods used to determine these properties....

  13. Atomic-scale disproportionation in amorphous silicon monoxide.

    Science.gov (United States)

    Hirata, Akihiko; Kohara, Shinji; Asada, Toshihiro; Arao, Masazumi; Yogi, Chihiro; Imai, Hideto; Tan, Yongwen; Fujita, Takeshi; Chen, Mingwei

    2016-01-01

    Solid silicon monoxide is an amorphous material which has been commercialized for many functional applications. However, the amorphous structure of silicon monoxide is a long-standing question because of the uncommon valence state of silicon in the oxide. It has been deduced that amorphous silicon monoxide undergoes an unusual disproportionation by forming silicon- and silicon-dioxide-like regions. Nevertheless, the direct experimental observation is still missing. Here we report the amorphous structure characterized by angstrom-beam electron diffraction, supplemented by synchrotron X-ray scattering and computer simulations. In addition to the theoretically predicted amorphous silicon and silicon-dioxide clusters, suboxide-type tetrahedral coordinates are detected by angstrom-beam electron diffraction at silicon/silicon-dioxide interfaces, which provides compelling experimental evidence on the atomic-scale disproportionation of amorphous silicon monoxide. Eventually we develop a heterostructure model of the disproportionated silicon monoxide which well explains the distinctive structure and properties of the amorphous material. PMID:27172815

  14. Atomic-scale disproportionation in amorphous silicon monoxide

    Science.gov (United States)

    Hirata, Akihiko; Kohara, Shinji; Asada, Toshihiro; Arao, Masazumi; Yogi, Chihiro; Imai, Hideto; Tan, Yongwen; Fujita, Takeshi; Chen, Mingwei

    2016-05-01

    Solid silicon monoxide is an amorphous material which has been commercialized for many functional applications. However, the amorphous structure of silicon monoxide is a long-standing question because of the uncommon valence state of silicon in the oxide. It has been deduced that amorphous silicon monoxide undergoes an unusual disproportionation by forming silicon- and silicon-dioxide-like regions. Nevertheless, the direct experimental observation is still missing. Here we report the amorphous structure characterized by angstrom-beam electron diffraction, supplemented by synchrotron X-ray scattering and computer simulations. In addition to the theoretically predicted amorphous silicon and silicon-dioxide clusters, suboxide-type tetrahedral coordinates are detected by angstrom-beam electron diffraction at silicon/silicon-dioxide interfaces, which provides compelling experimental evidence on the atomic-scale disproportionation of amorphous silicon monoxide. Eventually we develop a heterostructure model of the disproportionated silicon monoxide which well explains the distinctive structure and properties of the amorphous material.

  15. Rational design of Mg-Al mixed oxide-supported bimetallic catalysts for dry reforming of methane

    Energy Technology Data Exchange (ETDEWEB)

    Tsyganok, Andrey I. [Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, D' Iorio Hall, 10 Marie Curie Street, Ottawa, Ont. (Canada); Inaba, Mieko [Natural Gas Technology Development Team, Teikoku Oil Co., 9-23-30 Kitakarasuyama, Setagaya-ku, Tokyo 157-0061 (Japan); Tsunoda, Tatsuo; Uchida, Kunio; Suzuki, Kunio; Hayakawa, Takashi [Institute for Materials and Chemical Process, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba 305-8565 (Japan); Takehira, Katsuomi [Department of Applied Chemistry, Faculty of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan)

    2005-09-18

    A novel synthetic strategy for preparing bimetallic Ru-M (M=Cr, Fe, Co, Ni and Cu) catalysts, supported on Mg-Al mixed oxide, has been introduced. It was based on a 'memory effect', i.e. on the ability of Mg-Al mixed oxide to reconstruct a layered structure upon rehydration with an aqueous solution. By repeated calcinations-rehydration cycles, layered double hydroxide (LDH) precursors of catalysts containing two different metals were synthesized. Bimetallic catalysts were then generated (1) in situ from LDH under methane reforming reaction conditions and (2) from mixed metal oxides obtained by preliminary LDH calcination. Among all the LDH-derived catalysts, a Ru{sup 0.1%}-Ni{sup 5.0%}/MgAlO{sub x} sample revealed the highest activity and selectivity to syngas, a suitable durability and a low coking capacity. A promoting effect of ruthenium on catalytic function of supported nickel was demonstrated. Preliminary LDH calcination was shown to markedly affect the catalytic activity of the derived catalysts and especially their coking properties.

  16. Synthesis and Photocatalytic Activity of One-dimensional ZnO-Zn2SnO4 Mixed Oxide Nanowires

    Institute of Scientific and Technical Information of China (English)

    Xue-lian Bai; Nan Pan; Xiao-ping Wang; Hai-qian Wang

    2008-01-01

    Mixed oxide photocatalysts,ZnO-Zn2SnO4(ZnO-ZTO) nanowires with different sizes were prepared by a simple thermal evaporation method.The ZnO-ZTO nanowires were characterized with a scanning electron microscope,X-ray diffraction,high-resolution transmission electron microscopy,energy-dispersive spectrometer,and X-ray photoelectron spectra.The photocatalytic activity of the ZnO-ZTO mixed nanowires were studied by observing the photodegradation behaviors of methyl orange aqueous solution.The results suggest that the ZnO-ZTO mixed oxide nanowires have a higher photocatalytic activity than pure ZnO and Zn2SnO4 nanowires.The photocatalyst concentration in the solution distinctly affects the degradation rate,and our results show that higher photodegradation efficiency can be achieved with a smaller amount of ZnO-ZTO nanowire catalyst,as compared to the pure ZnO and ZTO nanowires.Moreover,the photocatalytic activity can also be enhanced by reducing the average diameter of the nanowires.The activity of pure ZnO and ZTO nanowires are also enhanced by physically mixing them.These results can be explained by the synergism between the two semiconductors.

  17. A high-throughput reactor system for optimization of Mo–V–Nb mixed oxide catalyst composition in ethane ODH

    KAUST Repository

    Zhu, Haibo

    2015-01-01

    75 Mo-V-Nb mixed oxide catalysts with a broad range of compositions were prepared by a simple evaporation method, and were screened for the ethane oxidative dehydrogenation (ODH) reaction. The compositions of these 75 catalysts were systematically changed by varying the Nb loading, and the Mo/V molar ratio. Characterization by XRD, XPS, H2-TPR and SEM revealed that an intimate structure is formed among the 3 components. The strong interaction among different components leads to the formation of a new phase or an "intimate structure". The dependency of conversion and selectivity on the catalyst composition was clearly demonstrated from the results of high-throughput testing. The optimized Mo-V-Nb molar composition was confirmed to be composed of a Nb content of 4-8%, a Mo content of 70-83%, and a V content of 12-25%. The enhanced catalytic performance of the mixed oxides is obviously due to the synergistic effects of the different components. The optimized compositions for ethane ODH revealed in our high-throughput tests and the structural information provided by our characterization studies can serve as the starting point for future efforts to improve the catalytic performance of Mo-V-Nb oxides. This journal is © The Royal Society of Chemistry.

  18. Atomic-scale disproportionation in amorphous silicon monoxide

    OpenAIRE

    Hirata, Akihiko; Kohara, Shinji; Asada, Toshihiro; Arao, Masazumi; Yogi, Chihiro; Imai, Hideto; Tan, Yongwen; Fujita, Takeshi; Chen, Mingwei

    2016-01-01

    Solid silicon monoxide is an amorphous material which has been commercialized for many functional applications. However, the amorphous structure of silicon monoxide is a long-standing question because of the uncommon valence state of silicon in the oxide. It has been deduced that amorphous silicon monoxide undergoes an unusual disproportionation by forming silicon- and silicon-dioxide-like regions. Nevertheless, the direct experimental observation is still missing. Here we report the amorphou...

  19. Effects of Calcination Temperature and Acid-Base Properties on Mixed Potential Ammonia Sensors Modified by Metal Oxides

    Directory of Open Access Journals (Sweden)

    Kenichi Shimizu

    2011-02-01

    Full Text Available Mixed potential sensors were fabriated using yttria-stabilized zirconia (YSZ as a solid electrolyte and a mixture of Au and various metal oxides as a sensing electrode. The effects of calcination temperature ranging from 600 to 1,000 °C and acid-base properties of the metal oxides on the sensing properties were examined. The selective sensing of ammonia was achieved by modification of the sensing electrode using MoO3, Bi2O3 and V2O5, while the use of WO3, Nb2O5 and MgO was not effective. The melting points of the former group were below 820 °C, while those of the latter group were higher than 1,000 °C. Among the former group, the selective sensing of ammonia was strongly dependent on the calcination temperature, which was optimum around melting point of the corresponding metal oxides. The good spreading of the metal oxides on the electrode is suggested to be one of the important factors. In the former group, the relative response of ammonia to propene was in the order of MoO3 > Bi2O3 > V2O5, which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified.

  20. Study of interfacial reactions and phase stabilization of mixed Sc, Dy, Hf high-k oxides by attenuated total reflectance infrared spectroscopy

    OpenAIRE

    Hardy, An; Adelmann, C; Van Elshocht, S.; Van den Rul, Heidi; Van Bael, Marlies; de Gendt, S.; D'Olieslaeger, Marc; Heyns, M.; Kittl, J. A.; Mullens, Jules

    2009-01-01

    Grazing angle attenuated total reflectance Fourier transform infrared spectroscopy is applied to study ultrathin film Hf4+, Sc3+ and Dy3+ oxides, due to its high surface sensitivity. The (multi) metal oxides studied, are of interest as high-k dielectrics. Important properties affecting the permittivity, such as the amorphous or crystalline phase and interfacial reactions, are characterized. Dy2O3 is prone to silicate formation on SiO2/Si substrates, which is expressed in DyScO3 as well, but s...

  1. Electrochromic Properties of Li+-Intercalated Amorphous Tungsten (aWO(3-x)) and Titanium (aTiO(2-x)) Oxide Thin Films

    OpenAIRE

    Triana, Carlos A.; Granqvist, Claes-Göran; Niklasson, Gunnar

    2014-01-01

    We report on electrochromic properties of stoichiometric and oxygen-deficient amorphous films, denoted aWO(3-x) and aTiO(2-x), under Li+-ion-electron inter/deintercalation. Optical characterization of the films in their as-deposited, fully intercalated (dark), and bleached states were performed by in-situ optical transmittance measurements. We explore electrochromism and optical absorption phenomena in the context of oxygen deficiency and nanostructure. Studies by cyclic voltammetry suggest g...

  2. Chemical and Radiochemical Composition of Thermally Stabilized Plutonium Oxide from the Plutonium Finishing Plant Considered as Alternate Feedstock for the Mixed Oxide Fuel Fabrication Facility

    Energy Technology Data Exchange (ETDEWEB)

    Tingey, Joel M.; Jones, Susan A.

    2005-07-01

    Eighteen plutonium oxide samples originating from the Plutonium Finishing Plant (PFP) on the Hanford Site were analyzed to provide additional data on the suitability of PFP thermally stabilized plutonium oxides and Rocky Flats oxides as alternate feedstock to the Mixed Oxide Fuel Fabrication Facility (MFFF). Radiochemical and chemical analyses were performed on fusions, acid leaches, and water leaches of these 18 samples. The results from these destructive analyses were compared with nondestructive analyses (NDA) performed at PFP and the acceptance criteria for the alternate feedstock. The plutonium oxide materials considered as alternate feedstock at Hanford originated from several different sources including Rocky Flats oxide, scrap from the Remote Mechanical C-Line (RMC) and the Plutonium Reclamation Facility (PRF), and materials from other plutonium conversion processes at Hanford. These materials were received at PFP as metals, oxides, and solutions. All of the material considered as alternate feedstock was converted to PuO2 and thermally stabilized by heating the PuO2 powder at 950 C in an oxidizing environment. The two samples from solutions were converted to PuO2 by precipitation with Mg(OH)2. The 18 plutonium oxide samples were grouped into four categories based on their origin. The Rocky Flats oxide was divided into two categories, low- and high-chloride Rocky Flats oxides. The other two categories were PRF/RMC scrap oxides, which included scrap from both process lines and oxides produced from solutions. The two solution samples came from samples that were being tested at Pacific Northwest National Laboratory because all of the plutonium oxide from solutions at PFP had already been processed and placed in 3013 containers. These samples originated at the PFP and are from plutonium nitrate product and double-pass filtrate solutions after they had been thermally stabilized. The other 16 samples originated from thermal stabilization batches before canning at

  3. Synthesis, characterization and magnetic behavior of Mg–Fe–Al mixed oxides based on layered double hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Heredia, Angélica C., E-mail: angelicacheredia@gmail.com [Universidad Tecnológica Nacional, Facultad Regional Córdoba-CITeQ, Maestro López esq. Cruz Roja Argentina, Ciudad Universitaria, 5016 Córdoba (Argentina); Oliva, Marcos I. [IFEG, Universidad Nacional de Córdoba, Córdoba (Argentina); CONICET (Argentina); Agú, Ulises [Universidad Tecnológica Nacional, Facultad Regional Córdoba-CITeQ, Maestro López esq. Cruz Roja Argentina, Ciudad Universitaria, 5016 Córdoba (Argentina); CONICET (Argentina); Zandalazini, Carlos I. [CONICET (Argentina); INFIQC, FCQ Universidad Nacional de Córdoba, Córdoba (Argentina); Marchetti, Sergio G. [CINDECA, UNLP, Buenos Aires (Argentina); Herrero, Eduardo R.; Crivello, Mónica E. [Universidad Tecnológica Nacional, Facultad Regional Córdoba-CITeQ, Maestro López esq. Cruz Roja Argentina, Ciudad Universitaria, 5016 Córdoba (Argentina)

    2013-09-15

    In the present work, Mg–Al–Fe layered double hydroxides were prepared by coprecipitation reaction with hydrothermal treatment. The characterization of precursors and their corresponding calcinated products (mixed oxides) were carried out by X ray diffraction, X-ray photoelectron spectroscopy (XPS), termogravimetric analysis and differential scanning calorimetry, diffuse reflectance UV–vis spectroscopy, specific surface area, Mössbauaer and magnetic properties. The Fe{sup 3+} species were observed in tetrahedrally and octahedrally coordination in brucite layered. The XPS analysis shows that the Fe{sup 3+} ions can be found in two coordination environments (tetrahedral and octahedral) as mixed oxides, and as spinel-structure. Oxides show a decrease in the specific surface areas when the iron loading is increased. The magnetic and Mössbauaer response show that MgAlFe mixed oxides are different behaviours such as different population ratios of ferromagnetic, weak-ferromagnetic, paramagnetic and superparamagnetic phases. The better crystallization of spinel structure with increased temperature, is correlated with the improved magnetic properties. - Highlights: • Mg–Al–Fe were successfully prepared by coprecipitation with hydrothermal treatment. • MgO, α-Fe{sub 2}O{sub 3,} MgFe{sub 2}O{sub 4} were detected by XRD in the calcined samples. • The Fe{sup 3+} is in tetrahedral and octahedral coordination in the brucite layered. • The specific surface area is directly related with the iron content. • The magnetic properties and MgFe{sub 2}O{sub 4} improve with increasing calcination temperature.

  4. Mg-AI Mixed Oxides Supported Bimetallic Au-Pd Nanoparticles with Superior Catalytic Properties in Aerobic Oxidation of Benzyl Alcohol and Glycerol

    Institute of Scientific and Technical Information of China (English)

    王亮; 张伟; 曾尚景; 苏党生; 孟祥举; 肖丰收

    2012-01-01

    Nano-sized Au and Pd catalysts are favorable for oxidations with molecular oxygen, and the preparation of this kind of nanoparticles with high catalytic activities is strongly desirable. We report a successful synthesis of bimetal- lic Au-Pd nanoparticles with rich edge and comer sites on unique support of Mg-AI mixed oxides (Au-Pd/MAO), which are favorable for producing metal nanoparticles with high degree of coordinative unsaturation of metal atoms The systematic microscopic characterizations confirm the bimetallic Au-Pd nanoparticles are present as Au-Pd alloy The irregular shape of the bimetallic nanoparticles are directly observed in HRTEM images. As we expected, Au-Pd/MAO gives very excellent catalytic performances in the aerobic oxidation of benzyl alcohol and glycerol. For example, Au-Pd/MAO shows very high TOF of 91000 h i at 433 K with molecular oxygen at air pressure in solvent-free oxidation of benzyl alcohol; this catalyst also shows relatively high selectivity for tartronic acid (TA- RAC, 36.6%) at high conversion (98.5%) in aerobic oxidation of glycerol. The superior catalytic properties of Au-Pd/MAO would be potentially important tbr production of fine chemicals.

  5. Corrosion resistant amorphous alloys

    International Nuclear Information System (INIS)

    A review of publication data on corrosion resistance of amorphous alloys and the methods of amorphization of surface layers of massive materials (laser treatment, iron implantation, detonation-gas spraying, cathode and ion sputtering, electrodeposition) was made. A study was made on corrosion properties of Fe66Cr11B10Si4 alloy in cast state and after laser irradiation, rendering the surface amorphous as well as the samples of Arenco iron and steel 20 with ion-plasma coatings of Fe-Cr-Ni-Ti alloy. It was established that amorphous coatings posses much higher corrosion resistance as compared to crystalline alloys on the same base

  6. Preparation of mixed oxides (Th,U)O{sub 2}: an evaluation of different techniques; Estudos de diferentes rotas de preparacao de oxidos binarios de torio e uranio

    Energy Technology Data Exchange (ETDEWEB)

    Ayoub, Jamil Mahmoud Said

    1999-07-01

    An evaluation of different ways of obtaining (Th-U)O{sub 2} mixed oxides is described. Coprecipitation, mechanical mixing of uranium and thorium powders, and the sol-gel technique were studied in order to get a large spectrum of knowledge of the process performance. The use of ultrasonic waves for the homogenization of the hydroxide mixture and microwave heating for powder drying was also investigated. Sol-gel showed the best results regarding the specific area for obtained samples. Oxide drying by microwave is an effective method to get mixed oxides for fuel fabrication. Neither coprecipitation nor mechanical mixing of the thorium and uranium oxide powders is suitable for the purpose. The obtained data are less than 70% than those achieved when sol-gel process is performed. Electronic microscopy, X-ray fluorescence and diffraction, thermogravimetry, specific gravidity and specific area determination (BET) used for sample characterization were convenient and accomplished good results. (author)

  7. Noise-like pulse based on dissipative four-wave-mixing with photonic crystal fiber filled by reduced graphene oxide

    CERN Document Server

    Gao, Lei; Huang, Wei

    2014-01-01

    A noise-like pulse based on dissipative four-wave-mixing in a fiber cavity with photonic crystal fiber filled by reduced graphene oxide is proposed. Due to large evanescent field provided by 3 cm photonic crystal fiber and ultrahigh nonlinearity of reduced graphene oxide, this mixed structure provides excellent saturable absorption and high nonlinearity, which are necessary for generating four-wave-mixing (FWM). We experimentally prove that the mode-locked laser transfers its energy from center wavelength to sidebands through degenerate FWM, and new frequencies are generated via cascaded FWM among those sidebands. During this process, the frequencies located in various orders of longitudinal modes of the ring cavity are supported, and others are suppressed due to destructive interference. As the longitudinal modes of the cavity with a spacing of 6.874 MHz are partially supported, the loosely fixed phase relationship results in noise-like pulse with a coherent peak of 530 fs locating on a pedestal of 730.693 p...

  8. Destruction of hazardous and mixed wastes using mediated electrochemical oxidation in a Ag(II)HNO3 bench scale system

    International Nuclear Information System (INIS)

    Mediated Electrochemical Oxidation (MEO) is a promising technology for the destruction of organic containing wastes and the remediation of mixed wastes containing transuranic components. The combination of a powerful oxidant and an acid solution allows the conversion of nearly all organics, whether present in hazardous or in mixed waste, to carbon dioxide. Insoluble transuranics are dissolved in this process and may be recovered by separation and precipitation.The MEO technique offers several advantages which are inherent in the system. First, the oxidation/dissolution processes are accomplished at near ambient pressures and temperatures (30-70 degrees C). Second, all waste stream components and oxidation products (with the exception of evolved gases) are contained in an aqueous environment. This electrolyte acts as an accumulator for inorganics which were present in the original waste stream, and the large volume of electrolyte provides a thermal buffer for the energy released during oxidation of the organics. Third, the generation of secondary waste is minimal, as the process needs no additional reagents. Finally, the entire process can be shut down by simply turning off the power, affording a level of control unavailable in some other techniques.Numerous groups, both in the United States and Europe, have made substantial progress in the last decade towards understanding the mechanistic pathways, kinetics, and engineering aspects of the process. At Lawrence Livermore National Laboratory, substantial contributions have been made to this knowledge base in these areas and others. Conceptual design and engineering development have been completed for a pilot plant-scale MEO system, and numerous data have been gathered on the efficacy of the process for a wide variety of anticipated waste components. This presentation will review the data collected at LLNL for a bench scale system based primarily on the use of a Ag(II) mediator in a nitric acid electrolyte; results

  9. Influence of Na diffusion on thermochromism of vanadium oxide films and suppression through mixed-alkali effect

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Mark J.; Wang, Junlan, E-mail: junlan@u.washington.edu

    2015-10-15

    Highlights: • Vanadium oxide films were reactively sputtered on three types of glass substrates. • Na diffusion from soda-lime glass undesirably inhibited thermochromism. • Na diffusion was suppressed by replacing half of sodium in glass with potassium. • Mixed-alkali effect promotes thermochromic VO{sub 2} films on glass substrates. - Abstract: Vanadium(IV) oxide possesses a reversible first-order phase transformation near 68 °C. Potential applications of the material include advanced optical devices and thermochromic smart windows. In this study, vanadium oxide films were grown on three types of glass substrates using reactive DC magnetron sputtering and were then annealed in air. The substrates were characterized with energy-dispersive X-ray spectroscopy, and the films were characterized with X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy, transmission electron microscopy, and UV-Vis-NIR spectrophotometry. The results show that the composition of the substrate has a major impact on the microstructure and optical properties of the deposited films. Sodium (Na) in the glass can undesirably inhibit thermochromism; however, replacing half of the Na with potassium (K) suppresses the Na diffusion and promotes the nucleation of pure VO{sub 2} with superior thermochromic functionality. The improved performance is attributed to the mixed-alkali effect between Na and K. These findings are both scientifically and technologically important since soda (Na{sub 2}O) is an essential flux material in glass products such as windows.

  10. Self-assembled hybrid metal oxide base catalysts prepared by simply mixing with organic modifiers

    OpenAIRE

    Tamura, Masazumi; Kishi, Ryota; Nakagawa, Yoshinao; Tomishige, Keiichi

    2015-01-01

    Multidentate materials formed by simply mixing heterogeneous and homogeneous components are promising for construction of versatile active sites on the surface of heterogeneous compounds, however, to the best of our knowledge, there are no reports on such materials. Self-assembly of hetero-hybrid catalytic materials occurs when heterogeneous catalysts having adjacent Lewis acid-Lewis base sites are mixed with an organic modifier that contains at least two Lewis base functional groups. Here we...

  11. Amorphization of mixed Ni and Zr powders with Ni-rich compositions by mechanical alloying. Mechanical alloying ni yoru Ni oyobi Zr kongo funmatsu (Ni-rich sosei ryoiki) no hishoshitsuka

    Energy Technology Data Exchange (ETDEWEB)

    Asahi, N.; Habu, T.; Yoshii, T.; Haruyama, O. (Science University of Tokyo, Tokyo (Japan). Faculty of Scinece and Technology)

    1991-01-25

    Amorphous Ni {sub x} Zr {sub 100 {minus} x} alloy powders (x=75, 80, 85, and 90) were synthesized from pure crystalline powders of Ni and Zr through a mechanical alloying method by high-energy ball milling in an argon atmosphere. The alloying and amorphization process was investigated using X-ray diffractometer and differential scanning calorimeter. Consequently, the X-ray scattering vector of the broad amorphous peak for the mechanically alloyed Ni-Zr amorphous powders were identical with those of liquid quenched amorphous alloys of the same compositions, except for x=90. In the initial stage of mechanical alloying, Ni powders were observed to diffuse preferentially into Zr powders. The crystallization temperature and the crystallization enthalpy of the Ni-Zr amorphous powders as a function of Ni composition were also investigated. The crystallization enthalpy in the Ni {sub 90} Zr {sub 10} composition powders provided a much lower value than that of the other Ni-Zr compositions powders. 11 refs., 7 figs.

  12. Inorganic ion exchanger based on tin/titanium mixed oxide doped with europium to be used in radioactive waste

    International Nuclear Information System (INIS)

    This work presents the results of synthesis and characterization of an inorganic ion exchanger based on tin/titanium mixed oxides doped with europium (SnO2/TiO2:Eu3+) to be used in environmental field. The adsorption study of nickel was realized in this exchanger to recover the nickel metal which is in thorium-nickel alloys used as electrode of discharge lamps. The studied exchanger was synthesized by neutralization of tin chloride (IV) and titanium chloride (III) mixed solution and characterized by thermogravimetric measurement (TG), Differential Scanning Calorimetry (DSC), X-Ray Powder Diffraction (XRD), Infrared Spectroscopy (IR) and Scanning Electron Microscopy (SEM). The adsorption study showed that these inorganic ion exchangers are good materials to recovery nickel with high weight distribution ratios (DwNi2+) and percent adsorption. (author)

  13. Amorphous iron (II) carbonate

    DEFF Research Database (Denmark)

    Sel, Ozlem; Radha, A.V.; Dideriksen, Knud;

    2012-01-01

    Abstract The synthesis, characterization and crystallization energetics of amorphous iron (II) carbonate (AFC) are reported. AFC may form as a precursor for siderite (FeCO3). The enthalpy of crystallization (DHcrys) of AFC is similar to that of amorphous magnesium carbonate (AMC) and more...

  14. Electrochromic Properties of Li+-Intercalated Amorphous Tungsten (aWO3-x) and Titanium (aTiO2-x) Oxide Thin Films

    Science.gov (United States)

    Triana, C. A.; Granqvist, C. G.; Niklasson, G. A.

    2014-11-01

    We report on electrochromic properties of stoichiometric and oxygen-deficient amorphous films, denoted aWO3-x and aTiO2-x, under Li+-ion-electron inter/deintercalation. Optical characterization of the films in their as-deposited, fully intercalated (dark), and bleached states were performed by in-situ optical transmittance measurements. We explore electrochromism and optical absorption phenomena in the context of oxygen deficiency and nanostructure. Studies by cyclic voltammetry suggest good optical modulation and charge capacity upon Li+-ion-electron inter/deintercalation for almost stoichiometric films.

  15. Electrochromic Properties of Li+-Intercalated Amorphous Tungsten (aWO3-x) and Titanium (aTiO2-x) Oxide Thin Films

    International Nuclear Information System (INIS)

    We report on electrochromic properties of stoichiometric and oxygen-deficient amorphous films, denoted aWO3-x and aTiO2-x, under Li+-ion-electron inter/deintercalation. Optical characterization of the films in their as-deposited, fully intercalated (dark), and bleached states were performed by in-situ optical transmittance measurements. We explore electrochromism and optical absorption phenomena in the context of oxygen deficiency and nanostructure. Studies by cyclic voltammetry suggest good optical modulation and charge capacity upon Li+-ion-electron inter/deintercalation for almost stoichiometric films

  16. Deactivation of a mixed oxide catalyst of Mo-V-Te-Nb-O composition in the reaction of oxidative ethane dehydrogenation

    Science.gov (United States)

    Mishanin, I. I.; Kalenchuk, A. N.; Maslakov, K. I.; Lunin, V. V.; Koklin, A. E.; Finashina, E. D.; Bogdan, V. I.

    2016-06-01

    The operational stability of a mixed oxide catalyst of Mo-V-Te-Nb-O composition in the oxidative dehydrogenation of ethane (ratio of C2H6: O2 = 3: 1) is studied in a flow reactor at temperatures of 340-400°C, a pressure of 1 atm, and a WHSV of the feed mixture of 800 h-1. It is found that the selectivity toward ethylene is 98% at 340°C, but the conversion of ethane at this temperature is only 6%; when the temperature is raised to 400°C, the conversion of ethane is increased to 37%, while the selectivity toward ethylene is reduced to 85%. Using physical and chemical means (XPS, SEM), it is found that the lack of oxidant in the reaction mixture leads to irreversible changes in the catalyst, i.e., reduced selectivity and activity. Raising the reaction temperature to 400°C allows the reduction of tellurium by ethane, from the +6 oxidation state to the zerovalent state, with its subsequent sublimation and the destruction of the catalytically active and selective phase; in its characteristics, the catalyst becomes similar to the Mo-V-Nb-O system containing no tellurium.

  17. Benchmark comparison of lattice codes PHOENIX-P, HELIOS and CASMO-3 for mixed-oxide fuel

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Ho-Cheol; Park, Moon-Gue; Lee, Sang-Hee [Korea Electric Power Research Inst., Taejon (Korea, Republic of)

    1996-09-01

    In this study we calculate the infinite multiplication factors (kinf) and the Doppler temperature coefficients(DTC) of two mixed-oxide(MOX) fuel rods with different plutonium contents by using PHOENIX-P, HELIOS and CASMO-3 codes. The results were compared against the reference values obtained by MCNP-3A continuous-energy Monte Carlo code. The purpose of this study is to benchmark the accuracy of these lattice codes. The PHOENIX-P`s Doppler coefficients calculated were in good agreement with the MCNP results within the Monte-Carlo uncertainty band which is in the order of {+-} 10% for the Doppler coefficients. (author)

  18. Toxicity of 1,1,1-Trichloroethane and Trichloroethene on a Mixed Culture of Methane-Oxidizing Bacteria

    OpenAIRE

    Broholm, Kim; Jensen, Bjørn K.; Christensen, Thomas H.; Olsen, Lajla

    1990-01-01

    The influence of trichloroethene (TCE; 0 to 65 mg/liter) and 1,1,1-trichloroethane (1,1,1-TCA; 0 to 103 mg/liter) on methane consumption of a mixed culture of methane-oxidizing bacteria was studied in laboratory batch experiments. Increasing concentrations of TCE or 1,1,1-TCA resulted in decreasing methane consumption. Methane consumption was totally inhibited at a concentration of 13 mg of TCE per liter, while methane consumption was still observed at the upper studied concentration of 103 m...

  19. Changes in Nitrogen-Fixing and Ammonia-Oxidizing Bacterial Communities in Soil of a Mixed Conifer Forest after Wildfire

    OpenAIRE

    Yeager, Chris M.; Northup, Diana E.; Grow, Christy C.; Barns, Susan M.; Kuske, Cheryl R.

    2005-01-01

    This study was undertaken to examine the effects of forest fire on two important groups of N-cycling bacteria in soil, the nitrogen-fixing and ammonia-oxidizing bacteria. Sequence and terminal restriction fragment length polymorphism (T-RFLP) analysis of nifH and amoA PCR amplicons was performed on DNA samples from unburned, moderately burned, and severely burned soils of a mixed conifer forest. PCR results indicated that the soil biomass and proportion of nitrogen-fixing and ammonia-oxidizin...

  20. Note: Application of CR-39 plastic nuclear track detectors for quality assurance of mixed oxide fuel pellets

    International Nuclear Information System (INIS)

    A CR-39 plastic nuclear track detector was used for quality assurance of mixed oxide fuel pellets for next-generation nuclear power plants. Plutonium (Pu) spot sizes and concentrations in the pellets are significant parameters for safe use in the plants. We developed an automatic Pu detection system based on dense α-radiation tracks in the CR-39 detectors. This system would greatly improve image processing time and measurement accuracy, and will be a powerful tool for rapid pellet quality assurance screening

  1. Solar energy as an alternate energy source to mixed oxide fuels in light-water cooled reactors

    International Nuclear Information System (INIS)

    Supplemental information pertaining to the generic environmental impact statement on the Pu recycling process for mixed oxide light-water cooled reactors (GESMO) was requested from several sources. In particular, the role of alternate sources of energy was to be explored and the implications of these alternate sources to the question of Pu recycle in LWRs were to be investigated. In this vein, solar energy as an alternate source is the main subject of this report, along with other information related to solar energy. The general conclusion is that solar energy should have little effect on the decisions concerning GESMO

  2. Structure and electronic properties of MoVO type mixed-metal oxides - a combined view by experiment and theory.

    Science.gov (United States)

    Chiu, Cheng-Chau; Vogt, Thomas; Zhao, Lili; Genest, Alexander; Rösch, Notker

    2015-08-21

    In this review we address recent efforts from experimental and theoretical side to study MoVO-type mixed metal oxides (MMOs) and their properties. We illustrate how structures of MMOs have been evaluated using a large variety of experimental techniques, such as electron microscopy, neutron diffraction, and X-ray diffraction. Furthermore, we discuss the current view on structure-catalysis correlations, derived from recent experiments. In a second part, we examine useful tools of theoretical chemistry for exploring MoVO-type systems. We discuss the need for using hybrid DFT methods and we analyze how, in the context of MMOs studies, semi-local DFT approximations can encounter problems due to a notable self-interaction error when describing oxidic species and reactions on them. In addition, we discuss various aspects of the model that are important when attempting to map complex MMO systems. PMID:26126874

  3. Preparation and conductivity of nanocrystalline rare earth mixed oxides SmFe1-xCoxO3-δ

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Nanocrystalline rare earth mixed oxides SmFe1 xCoxO3-δ were prepared by sol-gel method at 1 073 K for 2h calcination and characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that SmFe1-xCoxO3-δ has the structure ofperovskite type. The conductivity of the materials increases with the temperature rising and the maximum conductivity at 1 073 K is 2.6 S/cm with the best mole ratio of Fe3+ to Co3+ being 1: 4. This kind of oxide is a conductive ceramic material by means of conduction of electron and oxygen anion.

  4. Study of the dissolution of (U,P)O2 mixed oxides with a high plutonium content

    International Nuclear Information System (INIS)

    Plutonium from nuclear reactors is partially integrated in the fuel cycle as Mixed OXide (U,Pu)O2 (MOX). Their dissolution in nitric acid is needed to reprocess them in present reprocessing plants. The main difficulty of this study is that dissolution is a phenomenon depending on solution characteristics as well as the structural properties of the pellets, which depend themselves on the material fabrication process. After showing kinetic and thermodynamic dissolution data of mixed oxides in nitric media, an inventory of the parameters which affect the dissolution process has been made. A separable variable concept was introduced in order to describe the process by studying separately the role of chemical parameters of the solution and geometric parameters of the material. The first part of the study estimates the effect of nitric solution chemical parameters (concentrations, acidity, temperature) on the dissolution and underlines the role of the oxide surface protonation step. The second part of this work deals with the study of surface area evolution for materials with controlled plutonium rich heterogeneities. Experimental results show that the pellet surface undergoes erosion and is progressively weakened by the formation of fault lines in the bulk of the material followed by the dispersion of sub-millimeter fragments in the solution. An heterogeneous kinetic model derived from study of solid-gas interface systems has been applied to fuel pellets dissolution, allowing a mechanism to be proposed, based on surface dissolution of the oxide as well as fault creation in the volume. The dissolution kinetics are therefore dependant on the microstructure and mechanical strength and cohesion of the pellets. (author)

  5. Deterioration of yttria-stabilized zirconia by boron carbide alone or mixed with metallic or oxidized Fe, Cr, Zr mixtures

    Energy Technology Data Exchange (ETDEWEB)

    De Bremaecker, A., E-mail: adbremae@sckcen.be [Belgian Nuclear Research Center (SCK-CEN), NMS, Mol (Belgium); Ayrault, L., E-mail: laurent.ayrault@cea.fr [Institut de Radio-Protection et Sûreté Nucléaire/DPAM/SEMIC, Bât 702, CEN de Cadarache BP3, F-13115 Saint-Paul-lez-Durance (France); Clément, B. [Institut de Radio-Protection et Sûreté Nucléaire/DPAM/SEMIC, Bât 702, CEN de Cadarache BP3, F-13115 Saint-Paul-lez-Durance (France)

    2014-08-01

    In the frame of severe accident conditions (PHEBUS FPT3 test), different experiments were carried out on the interactions of 20% yttria-stabilized zirconia (YSZ) and 20% ceria-stab zirconia with boron carbide or its oxidation products (B{sub 2}O{sub 3}): either tests under steam between 1230° and 1700 °C with B{sub 4}C alone or B{sub 4}C mixed with metals, either tests under Ar with boron oxide present in a mixture of iron and chromium oxides. In all cases an interaction was observed with formation of intergranular yttrium borate. At 1700 °C boron oxide is able to “pump out” the Y stabiliser from the YSZ grains but also some trace elements (Ca and Al) and to form a eutectic containing YBO{sub 3} and yttrium calcium oxy-borate (YCOB). At the same time a substantial swelling (“bloating”) of the zirconia happens, qualitatively similar to the foaming of irradiated fuel in contact with a Zr-melt. In all samples the lowering of the Y (or Ce)-content in the YSZ grains is so sharp that in the interaction layers zirconia is no longer stabilized. This is important when YSZ is envisaged as simulant of UO{sub 2} or as inert matrix for Am-transmutation.

  6. Deterioration of yttria-stabilized zirconia by boron carbide alone or mixed with metallic or oxidized Fe, Cr, Zr mixtures

    Science.gov (United States)

    De Bremaecker, A.; Ayrault, L.; Clément, B.

    2014-08-01

    In the frame of severe accident conditions (PHEBUS FPT3 test), different experiments were carried out on the interactions of 20% yttria-stabilized zirconia (YSZ) and 20% ceria-stab zirconia with boron carbide or its oxidation products (B2O3): either tests under steam between 1230° and 1700 °C with B4C alone or B4C mixed with metals, either tests under Ar with boron oxide present in a mixture of iron and chromium oxides. In all cases an interaction was observed with formation of intergranular yttrium borate. At 1700 °C boron oxide is able to “pump out” the Y stabiliser from the YSZ grains but also some trace elements (Ca and Al) and to form a eutectic containing YBO3 and yttrium calcium oxy-borate (YCOB). At the same time a substantial swelling (“bloating”) of the zirconia happens, qualitatively similar to the foaming of irradiated fuel in contact with a Zr-melt. In all samples the lowering of the Y (or Ce)-content in the YSZ grains is so sharp that in the interaction layers zirconia is no longer stabilized. This is important when YSZ is envisaged as simulant of UO2 or as inert matrix for Am-transmutation.

  7. Controlling the oxygen potential to improve the densification and the solid solution formation of uranium-plutonium mixed oxides

    Science.gov (United States)

    Berzati, Ségolène; Vaudez, Stéphane; Belin, Renaud C.; Léchelle, Jacques; Marc, Yves; Richaud, Jean-Christophe; Heintz, Jean-Marc

    2014-04-01

    Diffusion mechanisms occurring during the sintering of oxide ceramics are affected by the oxygen content of the atmosphere, as it imposes the nature and the concentration of structural defects in the material. Thus, the oxygen partial pressure, p(O2), of the sintering gas has to be precisely controlled, otherwise a large dispersion in various parameters, critical for the manufacturing of ceramics such as nuclear oxides fuels, is likely to occur. In the present work, the densification behaviour and the solid solution formation of a mixed uranium-plutonium oxide (MOX) were investigated. The initial mixture, composed of 70% UO2 + 30% PuO2, was studied at p(O2) ranging from 10-15 to 10-4 atm up to 1873 K both with dilatometry and in situ high temperature X-ray diffraction. This study has shown that the initial oxides UO2+x and PuO2-x first densify during heating and then the solid solution formation starts at about 200 K higher. The densification and the formation of the solid solution both occur at a lower temperature when p(O2) increases. Based on this result, it is possible to better define the sintering atmosphere, eventually leading to optimized parameters such as density, oxygen stoichiometry and cations homogenization of nuclear ceramics and of a wide range of industrial ceramic materials.

  8. Melting behavior of irradiated mixed-oxide fuel: melting temperature measurements on eutectic systems. Summary report

    International Nuclear Information System (INIS)

    Observations of melting in oxide fuel pin irradiation experiments that are used to define power-to-melt limits for oxide fuels often refer to incipient melting. In this context the meaning of incipient is unclear and, as such, would be difficult to defend in licensing hearings conducted by the NRC. The primary cause of this incipient melting, occurring at a melting point significantly lower than that of the fuel, is believed to be the presence of fission products that can form eutectics with the fuel. Since barium, strontium and zirconium are three of the more prominent fission products, recent experimental work has focussed on the effects of these elements, as oxides, on the melting behavior of oxides fuel. Because of the interest indicated by the above mentioned work and the apparent need for confirmation of various postulated eutectics, attention was focussed in our recent experimental investigation on the possible eutectics formed between urania-based fuel and Ba-, Sr-oxides and between urania-based fuel and Ba-, Sr-zirconates. These compounds are the principal constituents of the gray ceramic phases that nucleate in irradiated oxide fuels

  9. Effect of mixed rare earth oxides and CaCO3 modification on the microstructure of an in-situ Mg2Si/Al-Si composite

    Institute of Scientific and Technical Information of China (English)

    LIU Zheng; LIN Jixing; JING Qingxiu

    2009-01-01

    The effects of mixed rare earth oxides and CaCO3 on the microstructure of an in-situ Mg2Si/Al-Si hypereutectic alloy composite were investigated by optical microscope, scanning electron microscope, and energy dispersive spectrum analysis. The results showed that the morphology of the primary Mg2Si phase particles changed from irregular or crosses to polygonal shape, their sizes decreased from 75 μm to about 25 μm, and the compound of both the oxide and CaCO3 was better than either the single mixed rare earth oxides or CaCO3.

  10. Electrochemical energy storage by polyaniline nanofibers: high gravity assisted oxidative polymerization vs. rapid mixing chemical oxidative polymerization.

    Science.gov (United States)

    Zhao, Yibo; Wei, Huige; Arowo, Moses; Yan, Xingru; Wu, Wei; Chen, Jianfeng; Wang, Yiran; Guo, Zhanhu

    2015-01-14

    Polyaniline (PANI) nanofibers prepared by high gravity chemical oxidative polymerization in a rotating packed bed (RPB) have demonstrated a much higher specific capacitance of 667.6 F g(-1) than 375.9 F g(-1) of the nanofibers produced by a stirred tank reactor (STR) at a gravimetric current of 10 A g(-1). Meanwhile, the cycling stability of the electrode is 62.2 and 65.9% for the nanofibers from RPB and STR after 500 cycles, respectively. PMID:25431883

  11. Nanostructured Metal Oxides And Mixed Metal Oxides, Methods Of Making These Nanoparticles, And Methods Of Their Use

    KAUST Repository

    Polshettiwar, Vivek

    2013-04-11

    Embodiments of the present disclosure provide for nanoparticles, methods of making nanoparticles, methods of using the nanoparticles, and the like. Nanoparticles of the present disclosure can have a variety of morphologies, which may lead to their use in a variety of technologies and processes. Nanoparticles of the present may be used in sensors, optics, mechanics, circuits, and the like. In addition, nanoparticles of the present disclosure may be used in catalytic reactions, for CO oxidation, as super-capacitors, in hydrogen storage, and the like.

  12. Interaction of hydrogenated amorphous silicon films with transparent conductive films

    OpenAIRE

    Kitagawa, M.; Mori, K; Ishihara, S.; Ohno, M.; Hirao, T.; Yoshioka, Y.; Kohiki, S

    1983-01-01

    The effects of the deposition temperature on the interaction of the hydrogenated amorphous silicon films with indium-tin-oxide and tin-oxide films have been investigated in the temperature range 150-300 degrees C, using Auger electron spectroscopy, secondary ion mass spectrometry, and scanning electron microscopy. It was found that the constituent atoms such as indium and tin are detected in the thin amorphous silicon films deposited. Around the interface between the transparent conductive fi...

  13. Trehalose amorphization and recrystallization.

    Science.gov (United States)

    Sussich, Fabiana; Cesàro, Attilio

    2008-10-13

    The stability of the amorphous trehalose prepared by using several procedures is presented and discussed. Amorphization is shown to occur by melting (T(m)=215 degrees C) or milling (room temperature) the crystalline anhydrous form TRE-beta. Fast dehydration of the di-hydrate crystalline polymorph, TRE-h, also produces an amorphous phase. Other dehydration procedures of TRE-h, such as microwave treatment, supercritical extraction or gentle heating at low scan rates, give variable fractions of the polymorph TRE-alpha, that undergo amorphization upon melting (at lower temperature, T(m)=130 degrees C). Additional procedures for amorphization, such as freeze-drying, spray-drying or evaporation of trehalose solutions, are discussed. All these procedures are classified depending on the capability of the undercooled liquid phase to undergo cold crystallization upon heating the glassy state at temperatures above the glass transition temperature (T(g)=120 degrees C). The recrystallizable amorphous phase is invariably obtained by the melt of the polymorph TRE-alpha, while other procedures always give an amorphous phase that is unable to crystallize above T(g). The existence of two different categories is analyzed in terms of the transformation paths and the hypothesis that the systems may exhibit different molecular mobilities.

  14. Redox properties and VOC oxidation activity of Cu catalysts supported on Ce{sub 1−x}Sm{sub x}O{sub δ} mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Konsolakis, Michalis, E-mail: mkonsol@science.tuc.gr [Laboratory of Physical Chemistry and Chemical Processes, Department of Sciences, Technical University of Crete, University Campus, 73100 Chania (Greece); Carabineiro, Sónia A.C., E-mail: scarabin@fe.up.pt [Laboratório de Catálise e Materiais (LCM), Laboratório Associado LSRE/LCM, Faculdade de Engenharia, Universidade do Porto, 4200-465 Porto (Portugal); Tavares, Pedro B. [CQVR, Centro de Química – Vila Real, Departamento de Química, Universidade de Trás-os-Montes e Alto Douro, 5001-911 Vila Real (Portugal); Figueiredo, José L. [Laboratório de Catálise e Materiais (LCM), Laboratório Associado LSRE/LCM, Faculdade de Engenharia, Universidade do Porto, 4200-465 Porto (Portugal)

    2013-10-15

    Highlights: • Complete elimination of ethyl acetate is achieved at 260 °C with Cu/CeO{sub 2} catalysts. • Samarium has a detrimental impact on VOC oxidation, proportional to its content. • Incorporation of Sm in ceria has a detrimental effect on textural characteristics and reducibility. • Increase of Sm/Ce ratio results in a more reduced Cu species, inactive for VOC oxidation. • A correlation between VOC activity and catalysts redox properties is established. -- Abstract: A series of Cu catalysts supported on Ce{sub 1−x}Sm{sub x}O{sub δ} mixed oxides with different molar contents (x = 0, 0.25, 0.5, 0.75 and 1), was prepared by wet impregnation and evaluated for volatile organic compounds (VOC) abatement, employing ethyl acetate as model molecule. An extensive characterization study was undertaken in order to correlate the morphological, structural and surface properties of catalysts with their oxidation activity. The optimum performance was obtained with Cu/CeO{sub 2} catalyst, which offers complete conversion of ethyl acetate into CO{sub 2} at temperatures as low as 260 °C. The catalytic performance of Cu/Ce{sub 1−x}Sm{sub x}O{sub δ} was interpreted on the basis of characterization studies, showing that incorporation of samarium in ceria has a detrimental effect on the textural characteristics and reducibility of catalysts. Moreover, high Sm/Ce atomic ratios (from 1 to 3) resulted in a more reduced copper species, compared to CeO{sub 2}-rich supports, suggesting the inability of these species to take part in the redox mechanism of VOC abatement. Sm/Ce surface atomic ratios are always much higher than the nominal ratios indicating an impoverishment of catalyst surface in cerium oxide, which is detrimental for VOC activity.

  15. Mixed polaronic-ionic conduction in lithium borate glasses and glass-ceramics containing copper oxide

    Science.gov (United States)

    Khalil, M. M. I.

    2007-03-01

    The effect of electric field strength on conduction in lithium borate glasses doped with CuO with different concentration was studied and the value of the jump distance of charge carrier was calculated. The conductivity measurements indicate that the conduction is due to non-adiabatic hopping of polarons and the activation energies are found to be temperature and concentration dependent. Lithium borate glasses are subjected to carefully-programmed thermal treatments which cause the nucleation and growth of crystalline phases. X-ray diffraction analysis confirmed the amorphous nature for the investigated glass sample and the formation of crystalline phase for annealed samples at 650 °C. The main separated crystalline phase is Li2B8O13. The scanning electron micrographs of some selected glasses showed a significant change in the morphology of the films investigated due to heat treatment of the glass samples. It was found that the dc-conductivity decreases with an increase of the HT temperature. The decrease of dc conductivity, with an increase of the HT temperature, can be related to the decrease in the number of free ions in the glass matrix. There is deviation from linearity at high temperature regions in the logσ-1/T plots for all investigated doped samples at a certain temperature at which the transition from polaronic to ionic conduction occurs. The hopping of small polarons is dominant at low temperatures, whereas the hopping of Li+ ions dominates at high temperatures.

  16. Mixed polaronic-ionic conduction in lithium borate glasses and glass-ceramics containing copper oxide

    Energy Technology Data Exchange (ETDEWEB)

    Khalil, M.M.I. [National Center for Radiation Research and Technology, Radiation Physics Department, Cairo (Egypt)

    2007-03-15

    The effect of electric field strength on conduction in lithium borate glasses doped with CuO with different concentration was studied and the value of the jump distance of charge carrier was calculated. The conductivity measurements indicate that the conduction is due to non-adiabatic hopping of polarons and the activation energies are found to be temperature and concentration dependent. Lithium borate glasses are subjected to carefully-programmed thermal treatments which cause the nucleation and growth of crystalline phases. X-ray diffraction analysis confirmed the amorphous nature for the investigated glass sample and the formation of crystalline phase for annealed samples at 650 C. The main separated crystalline phase is Li{sub 2}B{sub 8}O{sub 13}. The scanning electron micrographs of some selected glasses showed a significant change in the morphology of the films investigated due to heat treatment of the glass samples. It was found that the dc-conductivity decreases with an increase of the HT temperature. The decrease of dc conductivity, with an increase of the HT temperature, can be related to the decrease in the number of free ions in the glass matrix. There is deviation from linearity at high temperature regions in the log{sigma}-1/T plots for all investigated doped samples at a certain temperature at which the transition from polaronic to ionic conduction occurs. The hopping of small polarons is dominant at low temperatures, whereas the hopping of Li{sup +} ions dominates at high temperatures. (orig.)

  17. Charge distribution on plutonium-containing aerosols produced in mixed-oxide reactor fuel fabrication and the laboratory

    International Nuclear Information System (INIS)

    The inhalation toxicity of potentially toxic aerosols may be affected by the electrostatic charge on the particles. Charge may influence the deposition site during inhalation and therefore its subsequent clearance and dose patterns. The electrostatic charge distributions on plutonium-containing aerosols were measured with a miniature, parallel plate, aerosol electrical mobility spectrometer. Two aerosols were studied: a laboratory-produced 238PuO2 aerosol (15.8 Ci/g) and a plutonium mixed-oxide aerosol (PU-MOX, natural UO2 plus PuO2, 0.02 Ci/g) formed during industrial centerless grinding of mixed-oxide reactor fuel pellets. Plutonium-238 dioxide particles produced in the laboratory exhibited a small net positive charge within a few minutes after passing through a 85Kr discharger due to alpha particle emission removal of valence electrons. PU-MOX aerosols produced during centerless grinding showed a charge distribution essentially in Boltzmann equilibrium. The gross alpha aerosol concentrations (960-1200 nCi/l) within the glove box were sufficient to provide high ion concentrations capable of discharging the charge induced by mechanical and/or nuclear decay processes

  18. Determination of nitrogen in uranium-plutonium mixed oxide fuel by gas chromatography after fusion in an inert gas atmosphere

    International Nuclear Information System (INIS)

    A gas chromatographic technique has been developed for the determination of nitrogen in uranium-plutonium mixed oxide fuel after fusion in an inert gas atmosphere. When the sample and pure iron powder in a graphite crucible were heated to approximately 2500C by a resistance heating furnace, a large amount of carbon monoxide was evolved with a small amount of nitrogen and hydrogen. A gas chromatograph equipped with a pre-cut system was used for the separation of nitrogen from the carbon monoxide. Nitrogen separated by the gas chromatograph was determined by means of a thermal conductivity detector. Only 100mg of the sample was used, and the analysis requires about 10min. No specific skills for glove-box work are necessary. The relative standard deviation and detection limit (3σ-criterion) were less than 5% and 9μgg-1, respectively. The present method is not only applicable to the analysis of research samples but also to the quality control of uranium-plutonium mixed oxide fuel production lines

  19. Electrical Conductivity of Sintered Chromia Mixed with TiO2,CuO and Mn-Oxides

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The electrical conductivity of sintered Cr2O3 mixed with 2% and 5% (in molar fraction) TiO2 or CuO was investigated in the temperature range 500~900℃ in air and in Ar/4 vol. pct H2 atmospheres. The effect of different Mn-oxides on the electrical conductivity of Cr2O3 was also studied under the same conditions.From the conductivity measurements it is established that additions of TiO2 change the defect structure of Cr2O3 and the effect of TiO2 on the electrical conductivity is controlled by TiO2 concentration as well as temperature and O2 partial pressure of the surrounding atmosphere. The conductivity of Cr2O3 increased in air and decreased in the Ar/H2 atmosphere by CuO additions. The effect of CuO was discussed with possible changes in the defect concentration in Cr2O3. Mixing of Cr2O3 with different Mn-oxides at the same Mn to metal atom fraction decreased the conductivity in air and in Ar/H2 atmospheres. No clear correlation between the spinel fraction and the changes in conductivity could be found.

  20. Fluoride adsorption studies on mixed-phase nano iron oxides prepared by surfactant mediation-precipitation technique

    International Nuclear Information System (INIS)

    Mixed nano iron oxides powder containing goethite (α-FeOOH), hematite (α-Fe2O3) and ferrihydrite (Fe5HO8.4H2O) was synthesized through surfactant mediation-precipitation route using cetyltrimethyl ammonium bromide (CTAB). The X-ray diffraction, FTIR, TEM, Moessbauer spectroscopy were employed to characterize the sample. These studies confirmed the nano powder contained 77% goethite, 9% hematite and 14% ferrihydrite. Fluoride adsorption onto the synthesized sample was investigated using batch adsorption method. The experimental parameters chosen for adsorption studies were: pH (3.0-10.0), temperature (35-55 deg. C), concentrations of adsorbent (0.5-3.0 g/L), adsorbate (10-100 mg/L) and some anions. Adsorption of fluoride onto mixed iron oxide was initially very fast followed by a slow adsorption phase. By varying the initial pH in the range of 3.0-10.0, maximum adsorption was observed at a pH of 5.75. Presence of either SO42- or Cl- adversely affected the adsorption of fluoride in the order of SO42- > Cl-. The FTIR studies of fluoride loaded adsorbent showed that partly the adsorption on the surface took place at surface hydroxyl sites. Moessbauer studies indicated that the overall absorption had gone down after fluoride adsorption that implies it has reduced the crystalline bond strength. The relative absorption area of ferrihydrite was marginally increased from 14 to 17%.