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Sample records for surface vanadium peroxo-oxo

  1. Vanadium

    International Nuclear Information System (INIS)

    Duke, V.W.A.

    1983-07-01

    Although a relatively abundant element, vanadium occurs only rarely in sufficient concentration to be worked commercially. In most cases, vanadium is produced as a co-product of some other element, most commonly iron. The principal ore deposits of vanadium occur in titaniferous magnetites that have been formed by magnetic segregation. Important commercial deposits of vanadium also occur associated with uranium, and with phosphate deposits. The principal uses of vanadium are in the production of special purpose, particularly high-strength low-alloy steels, in the manufacture of titanium alloys, and as a catalyst, notably in the manufacture of sulphuric acid. Small quantities of vanadium, often in combination with niobium, are added to steel to bring about toughening through grain refinement, and increased tensile strength through precipitation hardening. Known world reserves of vanadium are very large and fully adequate to meet any foreseeable demand. By far the largest known deposits of vanadium occur in South Africa. Many other similar deposits are known, but are only exploited in the USSR and China. The present total world demand for vanadium amounts to about 40 000 tons of metal annually and this is produced primarily in four countries, South Africa, the USSR, the People's Republic of China and the United States of America, in that order. South Africa is the principal vanadium producing country in the world, supplying vanadium in various forms. Vanadium has a very low and non-accumulative toxicity; recovery plants can be operated in such a manner to ensure no air or steam pollution results

  2. Vanadium

    Science.gov (United States)

    Kelley, Karen D.; Scott, Clinton T.; Polyak, Désirée E.; Kimball, Bryn E.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Vanadium is used primarily in the production of steel alloys; as a catalyst for the chemical industry; in the making of ceramics, glasses, and pigments; and in vanadium redox-flow batteries (VRBs) for large-scale storage of electricity. World vanadium resources in 2012 were estimated to be 63 million metric tons, which include about 14 million metric tons of reserves. The majority of the vanadium produced in 2012 was from China, Russia, and South Africa.Vanadium is extracted from several different types of mineral deposits and from fossil fuels. These deposits include vanadiferous titanomagnetite (VTM) deposits, sandstone-hosted vanadium (with or without uranium) deposits (SSV deposits), and vanadium-rich black shales. VTM deposits are the principal source of vanadium and consist of magmatic accumulations of ilmenite and magnetite containing 0.2 to 1 weight percent vanadium pentoxide (V2O5). SSV deposits are another important source; these deposits have average ore grades that range from 0.1 to greater than 1 weight percent V2O5. The United States has been and is currently the main producer of vanadium from SSV deposits, particularly those on the Colorado Plateau. Vanadium-rich black shales occur in marine successions that were deposited in epeiric (inland) seas and on continental margins. Concentrations in these shales regularly exceed 0.18 weight percent V2O5 and can be as high as 1.7 weight percent V2O5. Small amounts of vanadium have been produced from the Alum Shale in Sweden and from ferrophosphorus slag generated during the reduction of phosphate to elemental phosphorus in ore from shales of the Phosphoria Formation in Idaho and Wyoming. Because vanadium enrichment occurs in beds that are typically only a few meters thick, most of the vanadiferous black shales are not currently economic, although they may become an important resource in the future. Significant amounts of vanadium are recovered as byproducts of petroleum refining, and processing of coal, tar

  3. Effect of iron on vanadium (001) strained surface magnetism

    Energy Technology Data Exchange (ETDEWEB)

    Elzain, M; Al-Barwani, M; Gismelseed, A; Al-Rawas, A; Yousif, A; Widatallah, H; Bouziane, K; Al-Omari, I, E-mail: elzain@squ.edu.o [Department of Physics, College Of Science, Box 36, Sultan Qaboos University, Al Khod 123 (Oman)

    2010-03-01

    The magnetism of the vanadium (001) surface has been a controversial subject on both theoretical and experiment fronts. Both strongly ferromagnetic and paramagnetic phases were reported. We have used the first principle full-potential linearized-augmented plane waves (FP-LAPW) as implemented in WIEN2k package to study the magnetic properties of strained surfaces of vanadium films as a function of film thickness. We found that for films thicker than about 11 monolayers, the magnetism of the strained surfaces converge to a constant value of about 0.15{mu}{sub B}. Introduction of Fe monolayers and impurities at the centre of the films affects the magnetic structure of thin films but has no influence on the surface magnetism of thicker films. For Fe monolayers positioned at the centre of thick films, the Fe atoms maintain magnetic moment of order 0.86{mu}{sub B}, a quadruple splitting of order -0.3 mm/s and a small negative isomer shift, while an Fe impurity has vanishing hyperfine fields and magnetic moment. In addition we have varied the location of the Fe monolayer and impurity within the V films and found that their position affects the surface magnetism.

  4. Tuning surface porosity on vanadium surface by low energy He{sup +} ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, J.K., E-mail: jtripat@purdue.edu; Novakowski, T.J.; Hassanein, A.

    2016-08-15

    Highlights: • Surface nanostructuring on vanadium surface using novel He{sup +} ion irradiation process. • Tuning surface-porosity using high-flux, low-energy He{sup +} ion irradiation at constant elevated sample temperature (823–173 K). • Presented top-down approach guarantees good contact between different crystallites. • Sequential significant enhancement in surface-pore edge size (and corresponding reduction in surface-pore density) with increasing sample temperature. - Abstract: In the present study, we report on tuning the surface porosity on vanadium surfaces using high-flux, low-energy He{sup +} ion irradiation as function of sample temperature. Polished, mirror-finished vanadium samples were irradiated with 100 eV He{sup +} ions at a constant ion-flux of 7.2 × 10{sup 20} ions m{sup −2} s{sup −1} for 1 h duration at constant sample temperatures in the wide range of 823–1173 K. Our results show that the surface porosity of V{sub 2}O{sub 5} (naturally oxidized vanadium porous structure, after taking out from UHV) is strongly correlated to the sample temperature and is highly tunable. In fact, the surface porosity significantly increases with reducing sample temperature and reaches up to ∼87%. Optical reflectivity on these highly porous V{sub 2}O{sub 5} surfaces show ∼0% optical reflectivity at 670 nm wavelength, which is very similar to that of “black metal”. Combined with the naturally high melting point of V{sub 2}O{sub 5}, this very low optical reflectivity suggests potential application in solar power concentration technology. Additionally, this top-down approach guarantees relatively good contact between the different crystallites and avoids electrical conductivity limitations (if required). Since V{sub 2}O{sub 5} is naturally a potential photocatalytic material, the resulting sub-micron-sized cube-shaped porous structures could be used in solar water splitting for hydrogen production in energy applications.

  5. XPS study of vanadium surface oxidation by oxygen ion bombardment

    Czech Academy of Sciences Publication Activity Database

    Alov, N.; Kutsko, D.; Spirovová, Ilona; Bastl, Zdeněk

    2006-01-01

    Roč. 600, č. 8 (2006), s. 1628-1631 ISSN 0039-6028 R&D Projects: GA ČR GA104/04/0467 Institutional research plan: CEZ:AV0Z40400503 Keywords : vanadium oxide * oxide film * ion-beam oxidation * X-ray photoelectron spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.880, year: 2006

  6. Study on the state of a surface of compounds of vanadium with light elements

    International Nuclear Information System (INIS)

    Povstugar, V.I.; Mikhajlova, S.S.; Trapeznikov, V.A.

    1976-01-01

    Roentgenoelectron study of powderlike compounds of vanadium with light elements (C, N, O, S) was carried out. The study was made in the temperature range of 70-500 deg C. The results were obtained in an electron magnetic spectrometer. Spectra of inner levels O 1S and V 2p and valance bands are presented. The experimental results can be employed for the study of synthesis problems of the given class of compounds. Due to high surface activity the study of catalytic properties of finely dispersed vanadium compounds by roentgenoelectron spectroscopy method gives much information about surface processes

  7. Efficiency improvement of multicrystalline silicon solar cells after surface and grain boundaries passivation using vanadium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Derbali, L., E-mail: rayan.slat@yahoo.fr [Photovoltaiec Laboratory, Research and Technology Center of Energy, Technopole de Borj-Cedria, BP 95, Hammam-Lif 2050 (Tunisia); Ezzaouia, H. [Photovoltaiec Laboratory, Research and Technology Center of Energy, Technopole de Borj-Cedria, BP 95, Hammam-Lif 2050 (Tunisia)

    2012-08-01

    Highlights: Black-Right-Pointing-Pointer Evaporation of vanadium pentoxide onto the front surface leads to reduce the surface reflectivity considerably. Black-Right-Pointing-Pointer An efficient surface passivation can be obtained after thermal treatment of obtained films. Black-Right-Pointing-Pointer Efficiency of the obtained solar cells has been improved noticeably after thermal treatment of deposited thin films. - Abstract: The aim of this work is to investigate the effect of vanadium oxide deposition onto the front surface of multicrystalline silicon (mc-Si) substrat, without any additional cost in the fabrication process and leading to an efficient surface and grain boundaries (GBs) passivation that have not been reported before. The lowest reflectance of mc-Si coated with vanadium oxide film of 9% was achieved by annealing the deposited film at 600 Degree-Sign C. Vanadium pentoxide (V{sub 2}O{sub 5}) were thermally evaporated onto the surface of mc-Si substrates, followed by a short annealing duration at a temperature ranging between 600 Degree-Sign C and 800 Degree-Sign C, under O{sub 2} atmosphere. The chemical composition of the films was analyzed by means of Fourier transform infrared spectroscopy (FTIR). Surface and cross-section morphology were determined by atomic force microscope (AFM) and a scanning electron microscope (SEM), respectively. The deposited vanadium oxide thin films make the possibility of combining in one processing step an antireflection coating deposition along with efficient surface state passivation, as compared to a reference wafer. Silicon solar cells based on untreated and treated mc-Si wafers were achieved. We showed that mc-silicon solar cells, subjected to the above treatment, have better short circuit currents and open-circuit voltages than those made from untreated wafers. Thus, the efficiency of obtained solar cells has been improved.

  8. Efficiency improvement of multicrystalline silicon solar cells after surface and grain boundaries passivation using vanadium oxide

    International Nuclear Information System (INIS)

    Derbali, L.; Ezzaouia, H.

    2012-01-01

    Highlights: ► Evaporation of vanadium pentoxide onto the front surface leads to reduce the surface reflectivity considerably. ► An efficient surface passivation can be obtained after thermal treatment of obtained films. ► Efficiency of the obtained solar cells has been improved noticeably after thermal treatment of deposited thin films. - Abstract: The aim of this work is to investigate the effect of vanadium oxide deposition onto the front surface of multicrystalline silicon (mc-Si) substrat, without any additional cost in the fabrication process and leading to an efficient surface and grain boundaries (GBs) passivation that have not been reported before. The lowest reflectance of mc-Si coated with vanadium oxide film of 9% was achieved by annealing the deposited film at 600 °C. Vanadium pentoxide (V 2 O 5 ) were thermally evaporated onto the surface of mc-Si substrates, followed by a short annealing duration at a temperature ranging between 600 °C and 800 °C, under O 2 atmosphere. The chemical composition of the films was analyzed by means of Fourier transform infrared spectroscopy (FTIR). Surface and cross-section morphology were determined by atomic force microscope (AFM) and a scanning electron microscope (SEM), respectively. The deposited vanadium oxide thin films make the possibility of combining in one processing step an antireflection coating deposition along with efficient surface state passivation, as compared to a reference wafer. Silicon solar cells based on untreated and treated mc-Si wafers were achieved. We showed that mc-silicon solar cells, subjected to the above treatment, have better short circuit currents and open-circuit voltages than those made from untreated wafers. Thus, the efficiency of obtained solar cells has been improved.

  9. Transient-response study of CO insertion into CHx surface intermediates on a vanadium-promoted rhodium catalyst

    NARCIS (Netherlands)

    Koerts, T.; Santen, van R.A.

    1992-01-01

    The rate of CO insertion into surface CHx species was investigated on silica-supported rhodium and rhodium-vanadium catalysts. Isotopically labelled 13CO was used in a transient kinetic experiment under steady-state conditions. A main conclusion is that vanadium promotion does not affect the rate of

  10. The effects of surface modification on carbon felt electrodes for use in vanadium redox flow batteries

    International Nuclear Information System (INIS)

    Kim, Ki Jae; Kim, Young-Jun; Kim, Jae-Hun; Park, Min-Sik

    2011-01-01

    Highlights: ► We observed the physical and chemical changes on the surface of carbon felts after various surface modifications. ► The surface area and chemistry of functional groups formed on the surface of carbon felt are critical to determine the kinetics of the redox reactions of vanadium ions. ► By incorporation of the surface modifications into the electrode preparation, the electrochemical activity of carbon felts could be notably enhanced. - Abstract: The surface of carbon felt electrodes has been modified for improving energy efficiency of vanadium redox flow batteries. For comparative purposes, the effects of various surface modifications such as mild oxidation, plasma treatment, and gamma-ray irradiation on the electrochemical properties of carbon felt electrodes were investigated at optimized conditions. The cell energy efficiency was improved from 68 to 75% after the mild oxidation of the carbon felt at 500 °C for 5 h. This efficiency improvement could be attributed to the increased surface area of the carbon felt electrode and the formation of functional groups on its surface as a result of the modification. On the basis of various structural and electrochemical characterizations, a relationship between the surface nature and electrochemical activity of the carbon felt electrodes is discussed.

  11. A functionalized surface modification with vanadium nanoparticles of various valences against implant-associated bloodstream infection

    Directory of Open Access Journals (Sweden)

    Wang J

    2017-04-01

    ions were released from these nano-VOx films in a sustained manner, and low-valence films possessed better biocompatibility with human fibroblasts. This work may provide new insights for biomedical applications of inorganic vanadium compounds and attract growing attention in this field. From the perspective of surface modification and functionalization, this study holds promise to avail the prophylaxis of bloodstream infections involving implantable biomedical devices. Keywords: surface modification, red blood cell, antibacterial activities, vanadium, nano­materials

  12. Electrochemical Properties of High Surface Area Vanadium Oxide Aerogels

    National Research Council Canada - National Science Library

    Dong, Winny

    2001-01-01

    .... Traditional composite electrode structures have prevented truly quantitative analysis of surface area effects in nanoscale battery materials, as well as a study of their innate electrochemical behavior...

  13. Specifics of adsorption and chemical processes on the surface of gamma-irradiated vanadium dioxide

    International Nuclear Information System (INIS)

    Kaurkovskaya, V.N.; Dzyubenko, L.S.; Doroshenko, V.N.; Chujko, A.A.; Shakhov, A.P.

    2006-01-01

    Effect of γ-irradiation on electrophysical properties and processes of thermal desorption of water from the surface of vanadium oxides V 2 O 3 -VO 2-δ -VO 2+δ -V 2 O 5 was investigated by derivatography and electric conductivity. Content of adsorbed water at the surface and phase composition of the surface was demonstrated to change under the action of low radiation doses. Surface electric conductivity of the irradiated samples VO 2-δ in the process of chemical reactions of adsorbed following irradiation benzoic acid and ethanol was established to be much above than in irradiated-free ones. It is presumed that metal-semiconductor phase transition at the surface of VO 2-δ during chemical reaction is intensified by irradiation [ru

  14. Arsenic, Fluoride and Vanadium in surface water (Chasicó Lake, Argentina

    Directory of Open Access Journals (Sweden)

    Maria laura ePuntoriero

    2014-06-01

    Full Text Available Chasicó Lake is the main water body in the southwest of the Chaco-Pampean plain. It shows some differences from the typical Pampean shallow lakes, such as high salinity and high arsenic and fluoride levels. The aim of this paper is to analyze the trace elements [arsenic (As, fluoride (F- and vanadium (V] present in Chasicó Lake. Surface and groundwater were sampled in dry and wet periods, during 2010 and 2011. Fluoride was determined with a selective electrode. As and V were determined by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES. Significant correlation in surface water was only found for As and F- (r=0.978, p<0.01. The As, F- and V concentration values were higher and more widely dispersed in surface water than in groundwater, as a consequence of evaporation. The fact that these elements do not correlate in surface water may also indicates that groundwater would not be the main source of origin of As, F- and V in surface water. The origin of these trace elements is from volcanic glass from Pampean loess. As, F- and V concentration were higher than in national and international guideline levels for the protection of aquatic biota. Hence, this issue is relevant since the silverside (Odontesthes bonariensis is the most important commercial species in Chasicó Lake. This fish is both consumed locally and exported to other South-American countries through commercial and sport fishing.

  15. Preparation, properties, and ESCA characterization of vanadium surface compounds on silicagel. 1

    International Nuclear Information System (INIS)

    Horvath, B.; Strutz, J.; Geyer-Lippmann, J.; Horvath, E.G.

    1981-01-01

    Binding energies (BE) or 18 pure vanadium compounds (V 2psup(3/2) niveau) were measured in selected oxygen and chlorine environments, linearity of BE vs. oxidation states scrutinized and appropriate model compounds chosen as comparative standards. The general trend is an increase of BE with formal oxidation state; in particular, it could be counterbalanced by electron donating/withdrawing ligands on the V atom. A graphical (computerized) background substraction method was utilized to remove an interfering O 1s satellite peak and to enhance accuracy of BE values in surface compounds. BEs of (triple bond Si-O) 3 V=O, (triple bond Si-O) 3 V, and (triple bond Si-O) 3 V-(O 2 ) were determined. By comparison to standards positive BE shifts of about 2.1 eV were derived indicating the strong electron withdrawing ('electron sink') effect of the support on V in surface compounds. This is the first reported ESCA data on a surface peroxo complex. (author)

  16. A highly permeable and enhanced surface area carbon-cloth electrode for vanadium redox flow batteries

    Science.gov (United States)

    Zhou, X. L.; Zhao, T. S.; Zeng, Y. K.; An, L.; Wei, L.

    2016-10-01

    In this work, a high-performance porous electrode, made of KOH-activated carbon-cloth, is developed for vanadium redox flow batteries (VRFBs). The macro-scale porous structure in the carbon cloth formed by weaving the carbon fibers in an ordered manner offers a low tortuosity (∼1.1) and a broad pore distribution from 5 μm to 100 μm, rendering the electrode a high hydraulic permeability and high effective ionic conductivity, which are beneficial for the electrolyte flow and ion transport through the porous electrode. The use of KOH activation method to create nano-scale pores on the carbon-fiber surfaces leads to a significant increase in the surface area for redox reactions from 2.39 m2 g-1 to 15.4 m2 g-1. The battery assembled with the present electrode delivers an energy efficiency of 80.1% and an electrolyte utilization of 74.6% at a current density of 400 mA cm-2, as opposed to an electrolyte utilization of 61.1% achieved by using a conventional carbon-paper electrode. Such a high performance is mainly attributed to the combination of the excellent mass/ion transport properties and the high surface area rendered by the present electrode. It is suggested that the KOH-activated carbon-cloth electrode is a promising candidate in redox flow batteries.

  17. Recovery of Vanadium from Magnetite Ore Using Direct Acid Leaching: Optimization of Parameters by Plackett-Burman and Response Surface Methodologies

    Science.gov (United States)

    Nejad, Davood Ghoddocy; Khanchi, Ali Reza; Taghizadeh, Majid

    2018-06-01

    Recovery of vanadium from magnetite ore by direct acid leaching is discussed. The proposed process, which employs a mixture of nitric and sulfuric acids, avoids pyrometallurgical treatments since such treatment consumes a high amount of energy. To determine the optimum conditions of vanadium recovery, the leaching process is optimized through Plackett-Burman (P-B) design and response surface methodology (RSM). In this respect, temperature (80-95°C), liquid to solid ratio (L/S) (3-10 mL g-1), sulfuric acid concentration (3-6 M), nitric acid concentration (5-10 vol.%) and time (4-8 h) are considered as the independent variables. According to the P-B approach, temperature and acid concentrations are, respectively, the most effective parameters in the leaching process. These parameters are optimized using RSM to maximize recovery of vanadium by direct acid leaching. In this way, 86.7% of vanadium can be extracted from magnetic ore.

  18. Scanning tunneling microscopy of the atomically smooth (001) surface of vanadium pentoxide V_2O_5 crystals

    International Nuclear Information System (INIS)

    Muslimov, A. E.; Butashin, A. V.; Kanevsky, V. M.

    2017-01-01

    The (001) cleavage surface of vanadium pentoxide (V_2O_5) crystal has been studied by scanning tunneling spectroscopy (STM). It is shown that the surface is not reconstructed; the STM image allows geometric lattice parameters to be determined with high accuracy. The nanostructure formed on the (001) cleavage surface of crystal consists of atomically smooth steps with a height multiple of unit-cell parameter c = 4.37 Å. The V_2O_5 crystal cleavages can be used as references in calibration of a scanning tunneling microscope under atmospheric conditions both along the (Ñ…, y) surface and normally to the sample surface (along the z axis). It is found that the terrace surface is not perfectly atomically smooth; its roughness is estimated to be ~0.5 Å. This circumstance may introduce an additional error into the microscope calibration along the z coordinate.

  19. Detection of hydrogen on metal surfaces. The interaction of H2 with polycrystalline vanadium

    International Nuclear Information System (INIS)

    Benninghoven, A.; Mueller, K.H.; Schemmer, M.

    1978-01-01

    Studies are reported of the secondary ion emission from hydrogen-covered vanadium, as a typical case from which the capacities and limits of secondary ion mass spectroscopy in this field could be determined. Experimental results are given and discussed. (U.K.)

  20. Multi-scale cell/surface interaction on modified titanium aluminum vanadium surfaces

    Science.gov (United States)

    Chen, Jianbo

    This dissertation presents a series of experimental studies of the effects of multi-scale cell/surface interactions on modified Ti-6Al-4V surfaces. These include laser-grooved surfaces; porous structures and RGD-coated laser-grooved surfaces. A nano-second DPSS UV lasers with a Gaussian pulse energy profile was used to introduce the desired micro-groove geometries onto Ti-6Al-4V surfaces. This was done without inducing micro-cracks or significant changes in surface chemistry within the heat affected zones. The desired 8-12 mum groove depths and widths were achieved by the control of pulse frequency, scan speed, and the lens focal length that controls spot size. The interactions between human osteosarcoma (HOS) cells and laser-grooved Ti-6Al-4V surfaces were investigated after 48 hours of cell culture. The cell behavior, including cell spreading, alignment and adhesion, was elucidated using scanning electronic microscopy (SEM), immuno-fluorescence staining and enzymatic detachment. Contact guidance was shown to increase as grooved spacing decreased. For the range of micro-groove geometries studied, micro-grooves with groove spacings of 20 mum provided the best combination of cell orientation and adhesion. Short-term adhesion experiments (15 mins to 1 day) also revealed that there is a positive correlation between cell orientation and cell adhesion. Contact guidance on the micro-grooved surfaces is shown to be enhanced by nano- and micro-scale asperities that provide sites for the attachment of lamellopodia during cell locomotion and spreading. Contact guidance is also promoted by the geometrical confinement provided by laser grooves. An experimental study of initial cell spreading and ingrowth into Ti-6Al-4V porous structures was also carried out on porous structures with different pore sizes and geometries. A combination of SEM, the tetrazolium salt (MTT) colorimetric assay and enzymatic detachment were used to study cell spreading and adhesion. The extent of cell

  1. Flux pinning by voids in surface-oxidized superconducting niobium and vanadium

    International Nuclear Information System (INIS)

    Meij, G.P. van der.

    1984-03-01

    The volume pinning force in several niobium and vanadium samples with voids is determined at various temperatures. Reasonable agreement is found with the collective pinning theory of Larkin and Ovchinnikov above the field of maximum pinning, if the flux line lattice is assumed to be amorphous in this region and if the elementary pinning force is calculated from the quasi-classical theory of Thuneberg, Kurkijaervi, and Rainer. Also some history and relaxation effects are studied in an alternating field. A qualitative explanation is given in terms of flux line dislocations, which reduce the shear strength of the flux line lattice. (Auth.)

  2. Flux pinning by voids in surface-oxidized superconducting niobium and vanadium

    International Nuclear Information System (INIS)

    Meij, G.P. van der.

    1984-01-01

    This thesis describes a study of flux pinning by small voids (roughly 10 nm) in the type II superconductors niobium and vanadium. These voids were created in rectangular foils (with typical dimensions of 30x3x0.2 mm) during an irradiation with fast neutrons in the High Flux Reactor at Petten at temperatures between 400 and 1000 0 C. The pinning force per unit volume is determined from the magnetic properties of the superconducting samples. The experiments were carried out in a slowly ramped magnetic field, as well as in a combination of a static and a much smaller alternating field. (Auth.)

  3. Vanadium - 1977

    International Nuclear Information System (INIS)

    Broderick, G.N.

    1977-01-01

    This report, with pertinent references, is a comprehensive description and analysis of the vanadium industry. Included is information on industry structure, size and organization; definitions, grades, and specifications; reserves and resources; geology; production and capacity; uses; technology; byproducts and coproducts; strategic considerations; economic and operating factors and problems; supply-demand relationships; and forecasts of supply and demand. Vanadium is used principally as an alloy in steel. Other important uses are in titanium alloys and in various chemical catalytic processes. The world supply of vanadium is sufficient to last far beyond the year 2000 at the present and projected rates of consumption. Almost all of the resources will economically yield vanadium only in conjunction with a coproduct

  4. VANADIUM ALLOYS

    Science.gov (United States)

    Smith, K.F.; Van Thyne, R.J.

    1959-05-12

    This patent deals with vanadium based ternary alloys useful as fuel element jackets. According to the invention the ternary vanadium alloys, prepared in an arc furnace, contain from 2.5 to 15% by weight titanium and from 0.5 to 10% by weight niobium. Characteristics of these alloys are good thermal conductivity, low neutron capture cross section, good corrosion resistance, good welding and fabricating properties, low expansion coefficient, and high strength.

  5. High surface area bio-waste based carbon as a superior electrode for vanadium redox flow battery

    Science.gov (United States)

    Maharjan, Makhan; Bhattarai, Arjun; Ulaganathan, Mani; Wai, Nyunt; Oo, Moe Ohnmar; Wang, Jing-Yuan; Lim, Tuti Mariana

    2017-09-01

    Activated carbon (AC) with high surface area (1901 m2 g-1) is synthesized from low cost bio-waste orange (Citrus sinensis) peel for vanadium redox flow battery (VRB). The composition, structure and electrochemical properties of orange peel derived AC (OP-AC) are characterized by elemental analyzer, field emission-scanning electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy. CV results show that OP-AC coated bipolar plate demonstrates improved electro-catalytic activity in both positive and negative side redox couples than the pristine bipolar plate electrode and this is ascribed to the high surface area of OP-AC which provides effective electrode area and better contact between the porous electrode and bipolar plate. Consequently, the performance of VRB in a static cell shows higher energy efficiency for OP-AC electrode than the pristine electrode at all current densities tested. The results suggest the OP-AC to be a promising electrode for VRB applications and can be incorporated into making conducting plastics electrode to lower the VRB cell stack weight and cost.

  6. Corrosion resistant surface for vanadium nitride and hafnium nitride layers as function of grain size

    Science.gov (United States)

    Escobar, C. A.; Caicedo, J. C.; Aperador, W.

    2014-01-01

    In this research it was studied vanadium nitride (VN) and hafnium nitride (HfN) film, which were deposited onto silicon (Si (100)) and AISI 4140 steel substrates via r.f. magnetron sputtering technique in Ar/N2 atmosphere with purity at 99.99% for both V and Hf metallic targets. Both films were approximately 1.2±0.1 μm thick. The crystallography structures that were evaluated via X-ray diffraction analysis (XRD) showed preferential orientations in the Bragg planes VN (200) and HfN (111). The chemical compositions for both films were characterized by EDX. Atomic Force Microscopy (AFM) was used to study the morphology; the results reveal grain sizes of 78±2 nm for VN and 58±2 nm for HfN and roughness values of 4.2±0.1 nm for VN and 1.5±0.1 nm for HfN films. The electrochemical performance in VN and HfN films deposited onto steel 4140 were studied by Tafel polarization curves and impedance spectroscopy methods (EIS) under contact with sodium chloride at 3.5 wt% solution, therefore, it was found that the corrosion rate decreased about 95% in VN and 99% for HfN films in relation to uncoated 4140 steel, thus demonstrating, the protecting effect of VN and HfN films under a corrosive environment as function of morphological characteristics (grain size). VN(grain size)=78±2.0 nm, VN(roughness)=4.2±0.1 nm, VN(corrosion rate)=40.87 μmy. HfN(grain size)=58±2.0 nm, HfN(roughness)=1.5±0.1 nm, HfN(corrosion rate)=0.205 μmy. It was possible to analyze that films with larger grain size, can be observed smaller grain boundary thus generating a higher corrosion rate, therefore, in this work it was found that the HfN layer has better corrosion resistance (low corrosion rate) in relation to VN film which presents a larger grain size, indicating that the low grain boundary in (VN films) does not restrict movement of the Cl- ion and in this way the corrosion rate increases dramatically.

  7. Effect of argon ion sputtering of surface on hydrogen permeation through vanadium

    International Nuclear Information System (INIS)

    Yamawaki, Michio; Namba, Takashi; Yoneoka, Toshiaki; Kanno, Masayoshi; Shida, Koji.

    1983-01-01

    In order to measure the hydrogen permeation rate through V with atomically cleaned surface, an Ar ion sputtering apparatus has been installed in the hydrogen permeability measuring system. The permeation rate of the initial specimen was found to be increased by about one order of magnitude after Ar ion sputtering of its upstream side surface. Repeating of such a sputter-cleaning was not so much effective in increasing the steady state permeation rate as the initial sputtering was, but it accelerated the transient response rate by a factor of 2 or 3. The transient response rate was also accelerated by the increase of hydrogen pressure, but this effect tended to be diminished by the sputter-cleaning of specimen surface. The surface impurity layer on the downstream side of specimen was also inferred to act as a diffusion barrier affecting the steady state permeation rate. The present value of activation energy for hydrogen permeation through V at temperatures below 873K was the smallest one ever obtained, showing that the surface effect was minimized in the present study on account of the surface sputter-cleaning in addition to the ultra high vacuum system. (author)

  8. Scanning tunneling microscopy of the atomically smooth (001) surface of vanadium pentoxide V{sub 2}O{sub 5} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Muslimov, A. E., E-mail: amuslimov@mail.ru; Butashin, A. V.; Kanevsky, V. M. [Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Research Centre “Crystallography and Photonics” (Russian Federation)

    2017-01-15

    The (001) cleavage surface of vanadium pentoxide (V{sub 2}O{sub 5}) crystal has been studied by scanning tunneling spectroscopy (STM). It is shown that the surface is not reconstructed; the STM image allows geometric lattice parameters to be determined with high accuracy. The nanostructure formed on the (001) cleavage surface of crystal consists of atomically smooth steps with a height multiple of unit-cell parameter c = 4.37 Å. The V{sub 2}O{sub 5} crystal cleavages can be used as references in calibration of a scanning tunneling microscope under atmospheric conditions both along the (Ñ…, y) surface and normally to the sample surface (along the z axis). It is found that the terrace surface is not perfectly atomically smooth; its roughness is estimated to be ~0.5 Å. This circumstance may introduce an additional error into the microscope calibration along the z coordinate.

  9. Vanadium and molybdenum oxide thin films on Au(111). Growth and surface characterization

    Energy Technology Data Exchange (ETDEWEB)

    Guimond, Sebastien

    2009-06-04

    The growth and the surface structure of well-ordered V{sub 2}O{sub 3}, V{sub 2}O{sub 5} and MoO{sub 3} thin films have been investigated in this work. These films are seen as model systems for the study of elementary reaction steps occurring on vanadia and molybdena-based selective oxidation catalysts. It is shown that well-ordered V{sub 2}O{sub 3}(0001) thin films can be prepared on Au(111). The films are terminated by vanadyl groups which are not part of the V{sub 2}O{sub 3} bulk structure. Electron irradiation specifically removes the oxygen atoms of the vanadyl groups, resulting in a V-terminated surface. The fraction of removed vanadyl groups is controlled by the electron dose. Such surfaces constitute interesting models to probe the relative role of both the vanadyl groups and the undercoordinated V ions at the surface of vanadia catalysts. The growth of well-ordered V{sub 2}O{sub 5}(001) and MoO{sub 3}(010) thin films containing few point defects is reported here for the first time. These films were grown on Au(111) by oxidation under 50 mbar O{sub 2} in a dedicated high pressure cell. Contrary to some of the results found in the literature, the films are not easily reduced by annealing in UHV. This evidences the contribution of radiation and surface contamination in some of the reported thermal reduction experiments. The growth of ultrathin V{sub 2}O{sub 5} and MoO{sub 3} layers on Au(111) results in formation of interface-specific monolayer structures. These layers are coincidence lattices and they do not correspond to any known oxide bulk structure. They are assumed to be stabilized by electronic interaction with Au(111). Their formation illustrates the polymorphic character and the ease of coordination units rearrangement which are characteristic of both oxides. The formation of a second layer apparently precedes the growth of bulk-like crystallites for both oxides. This observation is at odds with a common assumption that crystals nucleate as soon as a

  10. Vanadium and molybdenum oxide thin films on Au(111). Growth and surface characterization

    International Nuclear Information System (INIS)

    Guimond, Sebastien

    2009-01-01

    The growth and the surface structure of well-ordered V 2 O 3 , V 2 O 5 and MoO 3 thin films have been investigated in this work. These films are seen as model systems for the study of elementary reaction steps occurring on vanadia and molybdena-based selective oxidation catalysts. It is shown that well-ordered V 2 O 3 (0001) thin films can be prepared on Au(111). The films are terminated by vanadyl groups which are not part of the V 2 O 3 bulk structure. Electron irradiation specifically removes the oxygen atoms of the vanadyl groups, resulting in a V-terminated surface. The fraction of removed vanadyl groups is controlled by the electron dose. Such surfaces constitute interesting models to probe the relative role of both the vanadyl groups and the undercoordinated V ions at the surface of vanadia catalysts. The growth of well-ordered V 2 O 5 (001) and MoO 3 (010) thin films containing few point defects is reported here for the first time. These films were grown on Au(111) by oxidation under 50 mbar O 2 in a dedicated high pressure cell. Contrary to some of the results found in the literature, the films are not easily reduced by annealing in UHV. This evidences the contribution of radiation and surface contamination in some of the reported thermal reduction experiments. The growth of ultrathin V 2 O 5 and MoO 3 layers on Au(111) results in formation of interface-specific monolayer structures. These layers are coincidence lattices and they do not correspond to any known oxide bulk structure. They are assumed to be stabilized by electronic interaction with Au(111). Their formation illustrates the polymorphic character and the ease of coordination units rearrangement which are characteristic of both oxides. The formation of a second layer apparently precedes the growth of bulk-like crystallites for both oxides. This observation is at odds with a common assumption that crystals nucleate as soon as a monolayer is formed dur-ing the preparation of supported vanadia

  11. Topotactic synthesis of vanadium nitride solid foams

    International Nuclear Information System (INIS)

    Oyama, S.T.; Kapoor, R.; Oyama, H.T.; Hofmann, D.J.; Matijevic, E.

    1993-01-01

    Vanadium nitride has been synthesized with a surface area of 120 m 2 g -1 by temperature programmed nitridation of a foam-like vanadium oxide (35 m 2 g -1 ), precipitated from vanadate solutions. The nitridation reaction was established to be topotactic and pseudomorphous by x-ray powder diffraction and scanning electron microscopy. The crystallographic relationship between the nitride and oxide was {200}//{001}. The effect of precursor geometry on the product size and shape was investigated by employing vanadium oxide solids of different morphologies

  12. Significance of porous structure on degradatin of 2 2' dichloro diethyl sulphide and 2 chloroethyl ethyl sulphide on the surface of vanadium oxide nanostructure

    International Nuclear Information System (INIS)

    Singh, Beer; Mahato, T.H.; Srivastava, A.K.; Prasad, G.K.; Ganesan, K.; Vijayaraghavan, R.; Jain, Rajeev

    2011-01-01

    Degradation of the king of chemical warfare agent, 2 2' dichloro diethyl sulphide (HD), and its simulant 2 chloroethyl ethyl sulphide (CEES) were investigated on the surface of porous vanadium oxide nanotubes at room temperature (30 ± 2 ° C ). Reaction kinetics was monitored by GC-FID technique and the reaction products were characterized by GC-MS. Data indicates that HD degraded faster relative to CEES inside the solid decontaminant compared to the reported liquid phase degradation of CEES and HD. Data explores the role of hydrolysis, elimination and oxidation reactions in the detoxification of HD and CEES and the first order rate constant and t 1/2 were calculated to be 0.026 h -1 , 26.6 h for CEES and 0.052 h -1 , 13.24 h for HD. In this report faster degradation of HD compared to CEES was explained on the basis of porous structure.

  13. The effect of surface morphology on the response of Fe{sub 2}O{sub 3}-loaded vanadium oxide nanotubes gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Jin Wei [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, and School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070 (China); Chen Wen, E-mail: chenw@whut.edu.cn [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, and School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070 (China); Li Yue; Zhao Chunxia; Dai Ying [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, and School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070 (China)

    2011-06-01

    The effect of surface morphology on the response of an ethanol sensor based on vanadium nanotubes surface loaded with Fe{sub 2}O{sub 3} nanoparticles (Fe{sub 2}O{sub 3}/VONTs) was investigated in this work. The particle size of Fe{sub 2}O{sub 3} loaded on VONTs was varied by using novel citric acid-assisted hydrothermal method. In the synthesis progress, citric acid was used as a surfactant and chelate agent, which ensured the growth of a uniform Fe{sub 2}O{sub 3} loading on the nanotubes surface. The ethanol sensing properties was then measured for these Fe{sub 2}O{sub 3}/VONTs at 230-300 deg. C. The results showed that the sensor response increased with the particles size and the loading amount of Fe{sub 2}O{sub 3}. It appears that the load of Fe{sub 2}O{sub 3} on the VONTs surface increases the concentration of oxygen vacancies and decreases the concentration of free electrons. The effects of morphology on the sensor resistance were interpreted in terms of the Debye length and the difference in the number of active sites.

  14. Vanadium recovery process

    International Nuclear Information System (INIS)

    Pyrih, R.Z.; Rickard, R.S.

    1978-01-01

    A process for recovering vanadium values from carbonaceous type vanadium ores, and vanadium scrap, such as vanadium contaminated spent catalyst, is disclosed which comprises roasting the vanadium containing material in air at a temperature less than about 600 0 C to produce a material substantially devoid of organic matter, subjecting said roasted material to a further oxidizing roast in an oxygen atmosphere at a temperature of at least about 800 0 C for a period sufficient to convert substantially all of the vanadium to the soluble form, leaching the calcine with a suitable dilute mineral acid or water at a pH of neutral to about 2 to recover vanadium values, precipitating vanadium values as iron vanadate from the leach solution with a soluble iron compound at a pH from neutral to about 1, and recovering ferrovanadium from the iron vanadate by a reduction vacuum smelting operation. The conversion of vanadium in the ore to the soluble form by the oxidizing roast is accomplished without the addition of an alkaline salt during calcining

  15. Vanadium in South Africa

    International Nuclear Information System (INIS)

    Rohrman, B.

    1985-01-01

    This paper deals briefly with the history of vanadium and its uses, price movement, and world resources. It then describes the titanomagnetite ore of the Bushveld Complex, and the production of vanadium from this ore at Highveld Steel and Vanadium Corporation Limited, giving details of the various processes used, including the roast-leach, rotary-kiln, electric-smelting, shaking-ladle, and basic-oxygen-furnace operations. The paper concludes with a very brief account of the treatment of Highveld slags in Europe for the production of vanadium pentoxide and ferrovanadium

  16. Innovative coating of nanostructured vanadium carbide on the F/M cladding tube inner surface for mitigating the fuel cladding chemical interactions

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yong [Univ. of Florida, Gainesville, FL (United States); Phillpot, Simon [Univ. of Florida, Gainesville, FL (United States)

    2017-11-29

    500 oC, respectively. The coating layer contains both carbon and vanadium elements as quantified by WED, and the phases mainly consist of a mixture of V2C and VC, which was confirmed using X-ray diffraction patterns. In addition, the ratio between V and C varies with processing temperature, and it was observed that a higher temperature promotes the carbon adsorption and increases thickness of the coating. With optimized deposition conditions, we can apply the coating technique toward the actual T91 cladding materials, and provide the possibilities for the real application in sodium-cooled fast reactors (SFRs). Diffusion couple experiments were performed at both 550 oC and 690 oC, which corresponds to normal and aggressive operating temperatures, respectively. The results show that vanadium carbide coating with wider thickness (8 µm) and lower carbon concentration (27 at.%) reduced the width of the inter diffusion region, indicating that vanadium carbide coating can mitigate FCCI effectively. In specific, inter-diffusion between Fe and Ce was prohibited over most area, but Ce diffusion occurred toward the coating and the Fe substrate through thinner coating layer, which needs further optimization in terms of uniform coating thickness. Overall, it is concluded that this coating process can be successfully applied onto the inner surface of HT9 cladding tubes and the FCCI can be effectively mitigated if not totally eliminated.

  17. The vanadium/oxygen system in the analysis of sodium for oxygen

    International Nuclear Information System (INIS)

    Walker, J.A.J.; Price, W.B.

    1981-05-01

    An investigation of the V-O-Na system at 1023 K is described for oxygen in sodium contents of 5 to 25 ppm. Electron spectroscopy combined with depth profiling is used to determine the vanadium/oxygen ratios inwards from the surface of vanadium foil and these ratios are compared with theoretical predictions. The validity of the vanadium wire technique as an analytical method is examined and a model for the vanadium oxidation is suggested. (author)

  18. Vanadium pentoxide nanoparticles mimic vanadium haloperoxidases and thwart biofilm formation

    Science.gov (United States)

    Natalio, Filipe; André, Rute; Hartog, Aloysius F.; Stoll, Brigitte; Jochum, Klaus Peter; Wever, Ron; Tremel, Wolfgang

    2012-08-01

    Marine biofouling--the colonization of small marine microorganisms on surfaces that are directly exposed to seawater, such as ships' hulls--is an expensive problem that is currently without an environmentally compatible solution. Biofouling leads to increased hydrodynamic drag, which, in turn, causes increased fuel consumption and greenhouse gas emissions. Tributyltin-free antifouling coatings and paints based on metal complexes or biocides have been shown to efficiently prevent marine biofouling. However, these materials can damage the environment through metal leaching (for example, of copper and zinc) and bacteria resistance. Here, we show that vanadium pentoxide nanowires act like naturally occurring vanadium haloperoxidases to prevent marine biofouling. In the presence of bromide ions and hydrogen peroxide, the nanowires catalyse the oxidation of bromide ions to hypobromous acid (HOBr). Singlet molecular oxygen (1O2) is formed and this exerts strong antibacterial activity, which prevents marine biofouling without being toxic to marine biota. Vanadium pentoxide nanowires have the potential to be an alternative approach to conventional anti-biofouling agents.

  19. Significance of porous structure on degradatin of 2 2' dichloro diethyl sulphide and 2 chloroethyl ethyl sulphide on the surface of vanadium oxide nanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Beer, E-mail: beerbs5@rediffmail.com [Defence R and D Establishment, Jhansi Road, Gwalior, M.P 474002 (India); Mahato, T.H.; Srivastava, A.K.; Prasad, G.K.; Ganesan, K.; Vijayaraghavan, R. [Defence R and D Establishment, Jhansi Road, Gwalior, M.P 474002 (India); Jain, Rajeev [School of Studies in Chemistry, Jiwaji University, Gwalior, M.P. 474011 (India)

    2011-06-15

    Degradation of the king of chemical warfare agent, 2 2' dichloro diethyl sulphide (HD), and its simulant 2 chloroethyl ethyl sulphide (CEES) were investigated on the surface of porous vanadium oxide nanotubes at room temperature (30 {+-} 2{sup Degree-Sign }C ). Reaction kinetics was monitored by GC-FID technique and the reaction products were characterized by GC-MS. Data indicates that HD degraded faster relative to CEES inside the solid decontaminant compared to the reported liquid phase degradation of CEES and HD. Data explores the role of hydrolysis, elimination and oxidation reactions in the detoxification of HD and CEES and the first order rate constant and t{sub 1/2} were calculated to be 0.026 h{sup -1}, 26.6 h for CEES and 0.052 h{sup -1}, 13.24 h for HD. In this report faster degradation of HD compared to CEES was explained on the basis of porous structure.

  20. Recovery of vanadium oxide

    International Nuclear Information System (INIS)

    Bates, C.P.; Clark, N.E.

    1985-01-01

    This invention relates to the recovery of vanadium oxide from molten metal. The invention provides a method for recovering vanadium oxide from molten metal, which includes passing oxygen and at least one coolant gas or shroud into the molten metal by way of at least one elongate lance. The invention also provides an arrangement for the recovery of vanadium oxide from molten metal, which includes at least one elongate lance extending into the molten metal. The lance is provided with at least one elongate bore extending therethrough. Means are provided to allow at least oxygen and at least one coolant gas to pass through the lance and into the molten metal

  1. Formation of vanadium carbide precipitations at the surface of alloys: Thermodynamics and kinetics aspects; Bildung von Vanadiumcarbid-Ausscheidungen auf Legierungsoberflaechen: Thermodynamische und kinetische Aspekte

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, A.; Uebing, C. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)

    1998-12-31

    The paper describes the formation of vanadium carbides on the surface layers of Fe-3%V-C(100) alloys. The phase diagram calculated for this alloyed material using the ThermoCalc program package reveals a co-existence of ferritic matrix and V{sub 3}C{sub 2} at temperatures of T{<=}650 C. This carbide is instable at elevated temperatures, leading to co-existence of ferrite and the cubic VC{sub 1-x}. Experimental analyses revealed the formation of a 2D VC compound in the top layers of the surface of Fe-3%V-C(100) alloys, induced by equilibrium segregation. The paper explains the usefulness of thermodynamic and kinetic calculations for interpretation of precipitation phenomena in steels. Mathematically derived and experimental results of analyses for the case of non-equilibrium segregation showed excellent agreement in the determination of carbide thickness (nanometer scale) and time dependence of segregation under fast cooling conditions. (orig./CB) [Deutsch] In der vorliegenden Arbeit wurde die Bildung von Vanadiumcarbiden auf Fe-3%V-C(100)-Legierungsoberflaechen beschrieben. Das anhand des ThermoCalc-Programmpakets fuer diese Legierungszusammensetzung berechnete Phasendiagramm zeigt bei niedrigen Temperaturen T{<=}650 C die Koexistenz von ferritischer Matrix und V{sub 3}C{sub 2}. Bei hoeheren Temperaturen ist dieses Carbid instabil und es liegt Koexistenz von Ferrit und dem kubischen VC{sub 1-x} vor. Die experimentellen Untersuchungen zeigen die Ausbildung einer zweidimensionalen VC-Oberflaechenverbindung auf Fe-3%V-C(100)-Legierungsoberflaechen durch Gleichgewichtssegregation. Diese Arbeit zeigt, dass thermodynamische und kinetische Rechnungen bei der Deutung von Ausscheidungsphaenomenen in Staehlen sinnvoll eingesetzt werden koennen. Bei der Nichtgleichgewichtssegregation wurde bezueglich Carbiddicke (im Nanometerbereich) und Zeitabhaengigkeit der Ausscheidung bei schneller Abkuehlung eine hervorragende Uebereinstimmung zwischen Simulation und Experiment gefunden

  2. Vanadium research recharged

    International Nuclear Information System (INIS)

    Luntz, Stephen

    2011-01-01

    US President Barack Obama has described Maria Skyllas-Kazacos’ research as “one of the coolest things I’ve ever said out loud”. Vanadium redox batteries could be electricity’s ultimate storage mechanism.

  3. Determination of vanadium

    International Nuclear Information System (INIS)

    Stepin, V.V.; Kurbatova, V.I.; Fedorova, N.D.

    1980-01-01

    Titrimetric and potentiometric methods of vanadium determination in ferrovanadium are developed. The essence of the titrimetric method using phenylanthranilic acid as indicator is in the following. Ferrovanadium weighed amount is dissolved in H 2 SO 4 , vanadium is oxidated by potassium permanganate to V(5) and is titrated by a solution of double salt of sulfuric Fe(2) and ammonium in the presence of indicator. Potentiometric titration is carried out using the same indicator [ru

  4. Pathway and Surface Mechanism Studies of 1,3-butadiene Selective Oxidation Over Vanadium-Molybdenum-Oxygen Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, William David [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    The partial oxidation of 1,3-butadiene has been investigated over VMoO catalysts synthesized by sol-gel techniques. Surface areas were 9-14 m2/g, and compositions were within the solid solution regime, i.e. below 15.0 mol % MoO3/(MoO3 + V2O5). Laser Raman Spectroscopy and XRD data indicated that solid solutions were formed, and pre- and post-reaction XPS data indicated that catalyst surfaces contained some V+4 and were further reduced in 1,3-butadiene oxidation. A reaction pathway for 1,3-butadiene partial oxidation to maleic anhydride was shown to involve intermediates such as 3,4-epoxy-1-butene, crotonaldehyde, furan, and 2-butene-1,4-dial. The addition of water to the reaction stream substantially increased catalyst activity and improved selectivity to crotonaldehyde and furan at specific reaction temperatures. At higher water addition concentrations, furan selectivity increased from 12% to over 25%. The catalytic effects of water addition were related to competitive adsorption with various V2O5-based surface sites, including the vanadyl V=O, corner sharing V-O-V and edge sharing V-O oxygen. Higher levels of water addition were proposed to impose acidic character by dissociative adsorption. In addition, a novel combinatorial synthesis technique for VMoO was used to investigate the phase transitions of V2O5, solid solutions of Mo in V2O5, V9Mo6O40, and other reduced VMoO compounds, characterized by laser Raman spectroscopy. The natural composition gradient imposed by the sputter deposition apparatus was used to create VMoO arrays containing 225 samples ranging from 7.0-42 mol% MoO3/(V2O5 + MoO3), determined by EDS analysis.

  5. Interaction of titanium and vanadium with carbon dioxide under heating

    International Nuclear Information System (INIS)

    Vlasyuk, R.Z.; Kurovskij, V.Ya.; Lyapunov, V.P.; Radomysel'skij, I.D.

    1986-01-01

    The methods of gravitmetric and X-ray phase analysis as well as analysis of composition of gases in the heating chamber have been used to investigate the mechanism of titanium and vanadium interaction with carbon dioxide in the 300-1000 deg C temperature range. The analogy of mechanisms of the interaction of titanium and vanadium with carbon dioxide in oxides production on the metal surface with subsequent carbidizing treatment at temperatures above 800 deg C is shown. Temperature limits of material operation on the base of titanium or vanadium in carbon dioxide must not exceed 400 or 600 deg C, respectively

  6. Vanadium and affective disorders

    International Nuclear Information System (INIS)

    Naylor, G.J.

    1985-01-01

    The oxidation reduction state of vanadium will influence its inhibitory effect, and it has been suggested that the control of this oxidation reduction could be a physiological means of controlling Na-K ATPase and hence membrane transport. However, there is no general agreement on this. For such a hypothesis to be true, tissue concentrations of vanadium would need to be sufficient to cause inhibition of Na-K ATPase. There has been considerable variation in the concentration of vanadium reported to be present in human blood and plasma - e.g., 8.4 μmoleliter, 0.11 μmoleliter, 0.04 μmoleliter and 0.0006-0.018 μmliter. Methods of assay have varied, even including enzymic methods, but the two major methods now used are neutron activation analysis and atomic absorption spectrophotometry using an electrical flameless atomizer. Using neutron activation analysis, difficulties arise from the short half-ife of V 52 (3.76 min) and for the need to separate Na 24 and Cl 36 from the sample since their radiation interfere with those from V 52 . Results from preirradiation separation agree well with those from atomic absorption spectrophotometry, but those from postirradiation separation are usually much lower. Though there is no agreement on the physiological role of vanadium there is evidence that it plays a part in the etiology of manic-depressive psychosis

  7. Evaluation of the nanomechanical properties of vanadium and native oxide vanadium thin films prepared by RF magnetron sputtering

    International Nuclear Information System (INIS)

    Mamun, M.A.; Zhang, K.; Baumgart, H.; Elmustafa, A.A.

    2015-01-01

    Graphical abstract: - Highlights: • V films of 50, 75, 100 nm thickness were deposited on Si by RF magnetron sputtering. • We studied structural/mechanical properties by XRD, FE-SEM, AFM, and nanoindentation. • The hardness increased from 9.0 to 14.0 GPa for 100 to 50 nm. • The modulus showed no correlation with thickness or native oxide formation. • Native oxide formation resulted in grain enlargement and roughness reduction. - Abstract: Polycrystalline vanadium thin films of 50, 75, and 100 nm thickness were deposited by magnetron sputtering of a vanadium metal target of 2 inch diameter with 99.9% purity on native oxide covered Si substrates. One set of the fabricated samples were kept in moisture free environment and the other set was exposed to ambient air at room temperature for a long period of time that resulted in formation of native oxide prior to testing. The crystal structure and phase purity of the vanadium and the oxidized vanadium thin films were characterized by X-ray diffraction (XRD). The XRD results yield a preferential (1 1 0), and (2 0 0) orientation of the polycrystalline V films and (0 0 4) vanadium oxide (V 3 O 7 ). The vanadium films thickness were verified using field emission scanning electron microscopy and the films surface morphologies were inspected using atomic force microscopy (AFM). AFM images reveal surface roughness was observed to increase with increasing film thickness and also subsequent to oxidation at room temperature. The nanomechanical properties were measured by nanoindentation to evaluate the modulus and hardness of the vanadium and the oxidized vanadium thin films. The elastic modulus of the vanadium and the oxidized vanadium films was estimated as 150 GPa at 30% film thickness and the elastic modulus of the bulk vanadium target is estimated as 135 GPa. The measured hardness of the vanadium films at 30% film thickness varies between 9 and 14 GPa for the 100 and 50 nm films, respectively, exhibiting size effects

  8. Nanostructured Electrocatalysts for All-Vanadium Redox Flow Batteries.

    Science.gov (United States)

    Park, Minjoon; Ryu, Jaechan; Cho, Jaephil

    2015-10-01

    Vanadium redox reactions have been considered as a key factor affecting the energy efficiency of the all-vanadium redox flow batteries (VRFBs). This redox reaction determines the reaction kinetics of whole cells. However, poor kinetic reversibility and catalytic activity towards the V(2+)/V(3+) and VO(2+)/VO2(+) redox couples on the commonly used carbon substrate limit broader applications of VRFBs. Consequently, modified carbon substrates have been extensively investigated to improve vanadium redox reactions. In this Focus Review, recent progress on metal- and carbon-based nanomaterials as an electrocatalyst for VRFBs is discussed in detail, without the intention to provide a comprehensive review on the whole components of the system. Instead, the focus is mainly placed on the redox chemistry of vanadium ions at a surface of various metals, different dimensional carbons, nitrogen-doped carbon nanostructures, and metal-carbon composites. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Slag recycling of irradiated vanadium

    International Nuclear Information System (INIS)

    Gorman, P.K.

    1995-01-01

    An experimental inductoslag apparatus to recycle irradiated vanadium was fabricated and tested. An experimental electroslag apparatus was also used to test possible slags. The testing was carried out with slag materials that were fabricated along with impurity bearing vanadium samples. Results obtained include computer simulated thermochemical calculations and experimentally determined removal efficiencies of the transmutation impurities. Analyses of the samples before and after testing were carried out to determine if the slag did indeed remove the transmutation impurities from the irradiated vanadium

  10. Phonon dispersion in vanadium

    International Nuclear Information System (INIS)

    Ivanov, A.S.; Rumiantsev, A.Yu.

    1999-01-01

    Complete text of publication follows. Phonon dispersion curves in Vanadium metal are investigated by neutron inelastic scattering using three-axis spectrometers. Due to extremely low coherent scattering amplitude of neutrons in natural isotope mixture of vanadium the phonon frequencies could be determined in the energy range below about 15 meV. Several phonon groups were measured with the polarised neutron scattering set-up. It is demonstrated that the intensity of coherent inelastic scattering observed in the non-spin-flip channel vanishes in the spin-flip channel. The phonon density of states is measured on a single crystal keeping the momentum transfer equal to a vector of reciprocal lattice where the coherent inelastic scattering is suppressed. Phonon dispersion curves in vanadium, as measured by neutron and earlier by X-ray scattering, are described in frames of a charge-fluctuation model involving monopolar and dipolar degrees of freedom. The model parameters are compared for different transition metals with body-centred cubic-structure. (author)

  11. Low activation vanadium alloys

    International Nuclear Information System (INIS)

    Witzenburg, W. van.

    1991-01-01

    The properties and general characteristics of vanadium-base alloys are reviewed in terms of the materials requirements for fusion reactor first wall and blanket structures. In this review attention is focussed on radiation response including induced radioactivity, mechanical properties, compatibility with potential coolants, physical and thermal properties, fabricability and resources. Where possible, properties are compared to those of other leading candidate structural materials, e.g. austenitic and ferritic/martensitic steels. Vanadium alloys appear to offer advantages in the areas of long-term activation, mechanical properties at temperatures above 600 deg C, radiation resistance and thermo-hydraulic design, due to superior physical and thermal properties. They also have a potential for higher temperature operation in liquid lithium systems. Disadvantages are associated with their ability to retain high concentrations of hydrogen isotopes, higher cost, more difficult fabrication and welding. A particular concern regarding use of vanadium alloys relates their reactivity with non-metallic elements, such as oxygen and nitrogen. (author). 33 refs.; 2 figs.; 2 tabs

  12. Biodiesel production over copper vanadium phosphate

    International Nuclear Information System (INIS)

    Chen, Lei; Yin, Ping; Liu, Xiguang; Yang, Lixia; Yu, Zhongxi; Guo, Xin; Xin, Xinquan

    2011-01-01

    In the present study, copper vanadium phosphate (CuVOP) with three-dimensional network structure was synthesized by hydrothermal method, and was characterized by Infrared spectrum (IR), elemental analysis (EA), EDXRF (energy dispersive X ray fluorescence) etc. Moreover, soybean oil was used as feedstock for producing biodiesel, and biodiesel was produced by CuVOP-catalyzed transesterification process. Response surface methodology was employed to statistically evaluate and optimize the conditions for the maximum conversion to biodiesel, and the effects of amount of catalyst, ratio of methanol to oil, reaction time and reaction temperature were investigated by the 2 4 full-factorial central composite design. The maximum conversion is obtained at amount of catalyst of 1.5%, methanol/oil molar ratio of 6.75, reaction temperature of 65 o C and reaction time of 5 h. Copper vanadium phosphate CuVOP resulted very active in the transesterification reaction for biodiesel production. -- Research highlights: → Copper vanadium phosphate CuVOP with three-dimensional network structure was prepared successfully. Moreover, for the transesterification reaction of soybean oil with methanol under atmospheric pressure, CuVOP had higher catalytic activity and the effects of production conditions such as amount of catalysts etc. were analyzed by response surface methodology.

  13. Directed synthesis of bio-inorganic vanadium oxide composites using genetically modified filamentous phage

    International Nuclear Information System (INIS)

    Mueller, Michael; Baik, Seungyun; Jeon, Hojeong; Kim, Yuchan; Kim, Jungtae; Kim, Young Jun

    2015-01-01

    Highlights: • Phage is an excellent seeding for bio-templates for environmentally benign vanadium oxide nanocomposite synthesis. • The synthesized bio-inorganic vanadium oxide showed photodegradation activities. • The fabricated wt phage/vanadium oxide composite exhibited bundle-like structure. • The fabricated RSTB-phage/vanadium oxide composite exhibited a ball with a fiber-like nanostructure. • The virus/vanadium oxide composite could be applied in photocatalysts, sensors and nanoelectronic applications. - Abstract: The growth of crystalline vanadium oxide using a filamentous bacteriophage template was investigated using sequential incubation in a V 2 O 5 precursor. Using the genetic modification of the bacteriophage, we displayed two cysteines that constrained the RSTB-1 peptide on the major coat protein P8, resulting in vanadium oxide crystallization. The phage-driven vanadium oxide crystals with different topologies, microstructures, photodegradation and vanadium oxide composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), quartz microbalance and dissipation (QCM-D) and X-ray photoelectron spectroscopy (XPS). Non-specific electrostatic attraction between a wild-type phage (wt-phage) and vanadium cations in the V 2 O 5 precursor caused phage agglomeration and fiber formation along the length of the viral scaffold. As a result, the addition of recombinant phage (re-phage) in V 2 O 5 precursors formed heterogeneous structures, which led to efficient condensation of vanadium oxide crystal formation in lines, shown by QCM-D analysis. Furthermore, re-phage/V x O x composites showed significantly enhanced photodegradation activities compared with the synthesized wt-phage-V 2 O 5 composite under illumination. This study demonstrates that peptide-mediated vanadium oxide mineralization is governed by a complicated interplay of peptide sequence, local structure, kinetics and the presence of a mineralizing

  14. Interaction of titanium and vanadium with carbon dioxide in heating

    International Nuclear Information System (INIS)

    Vlasyuk, R.Z.; Kurovskii, V.Y.; Lyapunov, A.P.; Radomysel'skii, I.D.

    1986-01-01

    To obtain prediction data on the change in properties of titaniumand vanadium-base powder metallurgy materials operating in a carbon dioxide atmosphere, and also to clarify the mechanism of their interaction with the gas in this work, gravimetric investigations of specimens heated at temperatures of 300-1000 C and an x-ray diffraction analysis of their surface were made and the composition of the gas in the heating chamber was studied. The results of the investigations indicate a similarity between the mechanisms of interaction of titanium and vanadium with carbon dioxide including the formation of oxides on the surface of the metal with subsequent carbidization at temperatures above 800 C. On the basis of the data obtained, it may be concluded that the operating temperature limits of titanium- or vanadium-base materials in carbon dioxide must not exceed 400 and 600 C, respectively

  15. Vanadium recycling for fusion reactors

    International Nuclear Information System (INIS)

    Dolan, T.J.; Butterworth, G.J.

    1994-04-01

    Very stringent purity specifications must be applied to low activation vanadium alloys, in order to meet recycling goals requiring low residual dose rates after 50--100 years. Methods of vanadium production and purification which might meet these limits are described. Following a suitable cooling period after their use, the vanadium alloy components can be melted in a controlled atmosphere to remove volatile radioisotopes. The aim of the melting and decontamination process will be the achievement of dose rates low enough for ''hands-on'' refabrication of new reactor components from the reclaimed metal. The processes required to permit hands-on recycling appear to be technically feasible, and demonstration experiments are recommended. Background information relevant to the use of vanadium alloys in fusion reactors, including health hazards, resources, and economics, is provided

  16. Thermodynamic properties of vanadium

    International Nuclear Information System (INIS)

    Desai, P.D.

    1986-01-01

    This work reviews and discusses the data and information on the various thermodynamic properties of vanadium available through March 1985. These include the heat capacity and enthalpy, enthalpy of melting, vapor pressure, and enthalpy of vaporization. The existing data have been critically evaluated and analyzed, and the recommended values for heat capacity, enthalpy, entropy, and Gibbs energy function covering the temperature range from 1 to 3800 K have been generated. These values are referred to tempertures based on IPTS-1968. The units used for various properties are joules per mole (J. mol - 1 ). The estimated uncertainties in the heat capacity are +/-3% below 15 K, +/-10% from 15 to 150 K, +/-3% from 150 to 298.15 K, +/-2% from 298.15 to 1000 K, +/-3% from 1000 to the melting point (2202 K), and +/-5% in the liquid region

  17. Synthesis of vanadium trioxide

    International Nuclear Information System (INIS)

    Yankelevich, R.G.; Vinarov, I.V.; Sheka, I.A.; Pushek, N.G.

    1976-01-01

    There have been studied the conditions for production of vanadium trioxide in a single-stage process of V 2 O 5 reduction by gaseous ammonia. To determine the optimum conditions for V 2 O 5 reduction, there have been studied the temperature range of the reaction and the effect offered by the volumetric rate and time of ammonia injection. The following conditions have proved to be the optimum ones: temperature - 450 deg C, volumetric rate of NH 3 injection at a batch of 10 g - 4 l/h, time of recovery - 3 hours. In accordance with the adopted procedure there have been synthetized the samples containing 98 - 99% V 2 O 3 [ru

  18. Effects of dietary vanadium in mallard ducks

    Science.gov (United States)

    White, D.H.; Dieter, M.P.

    1978-01-01

    Adult mallard ducks fed 0, 1, 10, or 100 ppm vanadyl sulfate in the diet were sacrificed after 12 wk on treatment; tissues were analyzed for vanadium. No birds died during the study and body weights did not change. Vanadium accumulated to higher concentrations in the bone and liver than in other tissues. Concentrations in bones of hens were five times those in bones of drakes, suggesting an interaction between vanadium and calcium mobilization in laying hens. Vanadium concentrations in most tissues were significantly correlated and increased with treatment level. Lipid metabolism was altered in laying hens fed 100 ppm vanadium. Very little vanadium accumulated in the eggs of laying hens.

  19. Bronsted acid site number evaluation using isopropylamine decomposition on Y-zeolite contaminated with vanadium in a simultaneous DSC-TGA analyzer

    International Nuclear Information System (INIS)

    Osorio Perez, Yonnathan; Forero, Liliam Alexandra Palomeque; Torres, Diana Vanessa Cristiano; Trujillo, Carlos Alexander

    2008-01-01

    Acid-site catalyzed decomposition of isopropylamine was followed in a simultaneous DSC-TGA analyzer. USY zeolite samples with and without vanadium were studied. Results show that acid sites number decreases linearly with vanadium concentration in zeolite indicating that vanadium neutralizes acid sites on catalyst and the metal is able to move on the surface of the solid. The neutralizing species probably contain only one vanadium atom. The reaction enthalpy plus desorption heat of the products show that vanadium preferentially neutralizes the strongest acid sites on the zeolite. The application of the simultaneous DSC-TGA technique to quantify Bronsted acid sites on solids by this reaction is novel

  20. Analysis of vanadium slags, roasted and leached products. Determination of contents of total vanadium, chromium, sodium, and soluble vanadium

    International Nuclear Information System (INIS)

    Hasek, Z.

    1975-01-01

    Accurate, rapid and simple methods were elaborated of determining total vanadium, chromium, and sodium in vanadium slags, and in roasted and leached products in one sample batch. The analysis was conducted in a teflon vial using inorganic acids. A method od determining soluble vanadium in similar materials was also elaborated and verified. (B.S.)

  1. Determination of Leachable Vanadium (V) in Sediment

    African Journals Online (AJOL)

    NICO

    A method for speciation of vanadium in solid samples was developed for quantification of ... Experimental ... Sediments for Trace Metals), obtained from the National Research ... Determination of vanadium is not a simple task using ET-AAS.

  2. Possible Cardiotoxic Effects of Vanadium

    Directory of Open Access Journals (Sweden)

    Parveen Parkash

    1990-12-01

    Full Text Available Vanadium, a ubiquitous element, is physiologically and pharmacologically an active substance and is present in most of mammalian tissues Jandhala and Horn, 1983. Large corpus of information exists on the mode of action of vanadium on cardiac muscles (Jandhala and Horn, 1983., Solaro et al, 1980, but the basis of pharma­cological lesion underlying its cardiac toxi­city is still poorly understood. Except for the solitary report of Lewis (1958 to best of our knowledge no information exists on the effect of vanadium on the functioning of heart as shown by electrocardiography.Large amounts of vanadium are relea­sed into atmosphere by combustion of fossil fuel (Vouk, 1979 and due to rapid indus­trialisation its environmental concentra­tion is reported to be increasing (Goldberg et al, 1974., Jaffe and Walters, 1977., Vouk, 1979. This necessitates the monitoring of its environmental and occupational hazards. In the present study cardiac side effects of vanadium, as revealed through ECG has been investigated in rabbits, since the electrocardiogram of rabbit resembles with of man in essential details (Weisborth et al, 1974.

  3. Thermophysical data of liquid vanadium

    International Nuclear Information System (INIS)

    Pottlacher, G.; Huepf, T.; Wilthan, B.; Cagran, C.

    2007-01-01

    Although vanadium is commonly used as an additive in the steel production, literature data for thermophysical properties of vanadium around the melting point are sparse and show, where available a variation over a wide range. This manifests especially in the melting temperature (variation of ±30 K), heat of fusion, or specific enthalpy. This recent work presents the results of thermophysical measurements on vanadium including normal spectral emissivity at 684.5 nm. The aim was to obtain another full dataset of properties (enthalpy, heat of fusion, electrical resistivity, thermal conductivity, emissivity) of liquid vanadium to either confirm existing recommendations for certain properties or presenting newer measurements for comparison leading towards such recommendations. Summarizing, the following results for thermophysical properties at the melting point have been obtained: radiance temperature at melting (650 nm) T r,m = 1993 K, melting temperature T m = 2199 K, normal spectral emissivity at melting (684.5 nm) ε = 0.353. An observed feature of all measured data and results is, that a much better agreement with literature references exists for the liquid phase than in the solid state, thus we have restricted the presentation to liquid vanadium

  4. Determination of vanadium

    International Nuclear Information System (INIS)

    Stepin, V.V.; Kurbatova, V.I.; Fedorova, N.D.

    1980-01-01

    Techniques of vanadium determination in steels and alloys are developed. Extraction-photometric method with N-phenyl-benzohydroxamic acid when V content is 0.005-0.5% is suggested. Molar coefficient of the complex quenching at lambdasub(max)=530 nm constitutes 5750. Optimum concentration is 15-150 μg per 25 ml of the solution, determination limit is 0.05 μg/ml. Chloroform is an extracting agent. A photometric method with acetohydrazide of anthranilic acid is suggested for the analysis of alloyed steels at V content 0.03-1%. The lower limit of V determination constitutes 0.64 μg/ml. Effect of Fe is removed using phosphoric acid. Amperometric method for steels and alloys at V content from 0.05 to 5% and for steels and alloys containing more than 3% W and Cr is also developed. The method is based on amperometric titration with solution of double sulfuric salt of Fe(2) and ammonium [ru

  5. Determination of Leachable Vanadium (V) in Sediment

    African Journals Online (AJOL)

    NICO

    A method for speciation of vanadium in solid samples was developed for quantification of vanadium(+5) in solid samples of sediment Certified Reference Materials ... element in such environmental samples as soil, sediments and plants.3,4–5 Validation of the ... Sample Preparation for the Determination of. Vanadium(+5).

  6. Physicochemical properties of vanadium impregnated Al-PILCs: Effect of vanadium source

    Energy Technology Data Exchange (ETDEWEB)

    Balci, Suna, E-mail: sunabalci@gazi.edu.tr; Tecimer, Aylin

    2015-03-01

    resulted in less structural deformation in the final solid. Loading of the vanadyl sulfate hydrate (VOSO{sub 4}·H{sub 2}O) resulted in a higher V/Si ratio in the solid since both settling and ion exchange mechanism occured. The vanadium was usually bonded in the +5 oxide form, and the particles were settled between these layers and onto the outer surface of the clay particles. The existence of V–O structural bonds and Bronsted and Lewis acid sites were observed in the Fourier transform infrared spectroscopy (FTIR) results. Up to 300 °C dehydration with high mass loss was observed, followed by the decreases in mass loss, and finally, at around 900 °C, hydroxylation reactions were observed in the TGA/DTA analyses.

  7. The effect of coadsorbed oxygen on the reaction of methanol on Rh(111) and on a rhodium/vanadium surface alloy

    International Nuclear Information System (INIS)

    Schennach, R.; Krenn, G.; Rendulic, K.D.

    2002-01-01

    Full text: Molecular adsorption of methanol can be observed on all transition metal surfaces at low temperatures. Methanol is adsorbed on Rh (111) at 98 K. With increasing methanol exposure first a mono-layer and then multi-layers of methanol are formed at this surface temperature. During heating, desorption of the methanol from physisorbed multi-layers is detected at about 120 K, followed by desorption of methanol from a chemisorbed mono-layer at 170 K. About 50 % of the adsorbed methanol undergoes a dehydrogenation reaction to form hydrogen and carbon monoxide adsorbed on the surface. These reaction products desorb at 300 K and 480 K, respectively. Less than 0.05 monolayers of coadsorbed oxygen increases the amount of methanol that reacts on the surface to about 80 %. Experiments using a Rh/V surface alloy were performed, in order to distinguish between steric and electronic effects in the adsorption and reaction processes. Deposition of 0.3 monolayers of V on the Rh (111) surface leads to the formation of a subsurface alloy, with V atoms in the second atomic layer only. The initial reaction probability was measured as a function of surface temperature and molecular beam energy. A marked difference was found between the two surfaces. On the clean surface methanol adsorption and reaction stops above 198 K, whereas on the alloy surface adsorption and subsequent reaction occurs up to 473 K. The effects of coadsorbed oxygen are similar on both surfaces. The results are discussed in terms of the possible reactions of the adsorbed methanol on the surface. (author)

  8. Melting technique for vanadium containing steels

    Energy Technology Data Exchange (ETDEWEB)

    Grishanov, M P; Gutovskij, I B; Vakhrushev, A S

    1980-04-28

    To descrease cost price of high-quality vanadium steels a method of their melting in open-hearth furnaces with acid lining using slag-metal fraction of vanadium, which is loaded in the content of 2.1-4.7% of melting mass, is suggested. Introduction of slag-metal fraction of vanadium ensures the formation of slag with composition that guarantees the necessary content of vanadium in steel and does not require introduction of expensive vanadium-containing ferroalloys into the melt.

  9. Global biogeochemical cycle of vanadium.

    Science.gov (United States)

    Schlesinger, William H; Klein, Emily M; Vengosh, Avner

    2017-12-26

    Synthesizing published data, we provide a quantitative summary of the global biogeochemical cycle of vanadium (V), including both human-derived and natural fluxes. Through mining of V ores (130 × 10 9 g V/y) and extraction and combustion of fossil fuels (600 × 10 9 g V/y), humans are the predominant force in the geochemical cycle of V at Earth's surface. Human emissions of V to the atmosphere are now likely to exceed background emissions by as much as a factor of 1.7, and, presumably, we have altered the deposition of V from the atmosphere by a similar amount. Excessive V in air and water has potential, but poorly documented, consequences for human health. Much of the atmospheric flux probably derives from emissions from the combustion of fossil fuels, but the magnitude of this flux depends on the type of fuel, with relatively low emissions from coal and higher contributions from heavy crude oils, tar sands bitumen, and petroleum coke. Increasing interest in petroleum derived from unconventional deposits is likely to lead to greater emissions of V to the atmosphere in the near future. Our analysis further suggests that the flux of V in rivers has been incremented by about 15% from human activities. Overall, the budget of dissolved V in the oceans is remarkably well balanced-with about 40 × 10 9 g V/y to 50 × 10 9 g V/y inputs and outputs, and a mean residence time for dissolved V in seawater of about 130,000 y with respect to inputs from rivers.

  10. Characterization of vanadium-doped mesoporous titania and its adsorption of gaseous benzene

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen-Phan, Thuy-Duong; Song, Myoung Bock; Yun, Hyunran; Kim, Eui Jung; Oh, Eun-Suok [School of Chemical Engineering and Bioengineering, University of Ulsan, Mugeo-dong, Nam-gu, Ulsan 680-749 (Korea, Republic of); Shin, Eun Woo, E-mail: ewshin@mail.ulsan.ac.kr [School of Chemical Engineering and Bioengineering, University of Ulsan, Mugeo-dong, Nam-gu, Ulsan 680-749 (Korea, Republic of)

    2011-01-01

    A series of vanadium-doped mesoporous titania with different metal contents was synthesized in the study via a sol-gel process with the assistance of a dodecylamine surfactant. The existence of vanadium ions not only suppressed crystallization and sintering but also enhanced the porosity of the mesoporous TiO{sub 2}. Varying the vanadium concentration led to significant changes in the chemical oxidation state of each component. The presence of metal dopants significantly improved the removal efficiency of benzene and the doping the titania with 5 mol% vanadium removed the most benzene, regardless of the adsorption temperature. The adsorption behavior was elucidated by the specific surface area, the interactions between surface hydroxyl groups and the {pi}-electrons of benzene, and the formation of {sigma}-bonding and d-{pi}* back-donation between the adsorbent and organic compounds.

  11. Researches on vanadium and its compounds; Recherches sur le Vanadium et ses composes

    Energy Technology Data Exchange (ETDEWEB)

    Morette, Andre

    1937-06-03

    In this research thesis, the author proposes a new study of the action of some reduction agents on two groups of vanadium compounds, oxides and chlorides. Thus, he reports the study of the circumstances of reduction of vanadium oxides by carbon and of vanadium carburization from these compounds. He also reports the determination of the composition of vanadium melts obtained at high temperatures (either in a vacuum furnace or with an electric arc furnace). In order to determine in which conditions the processing of vanadium oxides could produce the pure metal, the author studied the action of calcium and magnesium on the vanadium pentoxide and trioxide. The second part of the thesis addresses the preparation of pure vanadium from vanadium anhydride chlorides. Then, the author reports the development of processes which could easily produce powdered vanadium [French] Nous nous sommes propose de reprendre l'etude de l'action de quelques reducteurs sur les deux groupes de composes du vanadium, oxydes et chlorures. Nous avons ete ainsi amene a preciser les circonstances de la reduction des oxydes de vanadium par le carbone et de la carburation du vanadium a partir de ceux-ci, puis a determiner la constitution des fontes de vanadium obtenues a haute temperature, soit au four a vide, soit au four a arc. D'autre part, en vue de determiner dans quelles conditions le traitement des oxydes de vanadium pourrait conduire au metal pur, nous avons repris et complete des travaux anterieurs concernant l'action du calcium et du magnesium sur le pentoxyde ou eventuellement le trioxyde de vanadium. Une seconde partie de notre these a ete consacree a la preparation du vanadium pur a partir des chlorures anhydres de vanadium. Nous nous sommes attache a trouver le mode operatoire le plus favorable pour l'obtention de chacun d'eux. Il nous a ete donne ainsi l'occasion de preciser certaines de leurs proprietes physiques et chimiques. Puis, a la suite d'essais systematiques, nous avons

  12. Vanadium Compounds as PTP Inhibitors

    Directory of Open Access Journals (Sweden)

    Elsa Irving

    2017-12-01

    Full Text Available Phosphotyrosine signaling is regulated by the opposing actions of protein tyrosine kinases (PTKs and protein tyrosine phosphatases (PTPs. Here we discuss the potential of vanadium derivatives as PTP enzyme inhibitors and metallotherapeutics. We describe how vanadate in the V oxidized state is thought to inhibit PTPs, thus acting as a pan-inhibitor of this enzyme superfamily. We discuss recent developments in the biological and biochemical actions of more complex vanadium derivatives, including decavanadate and in particular the growing number of oxidovanadium compounds with organic ligands. Pre-clinical studies involving these compounds are discussed in the anti-diabetic and anti-cancer contexts. Although in many cases PTP inhibition has been implicated, it is also clear that many such compounds have further biochemical effects in cells. There also remain concerns surrounding off-target toxicities and long-term use of vanadium compounds in vivo in humans, hindering their progress through clinical trials. Despite these current misgivings, interest in these chemicals continues and many believe they could still have therapeutic potential. If so, we argue that this field would benefit from greater focus on improving the delivery and tissue targeting of vanadium compounds in order to minimize off-target toxicities. This may then harness their full therapeutic potential.

  13. Characterization of vanadium flow battery

    Energy Technology Data Exchange (ETDEWEB)

    Bindner, H.; Ekman, C.; Gehrke, O.; Isleifsson, F.

    2010-10-15

    This report summarizes the work done at Risoe DTU testing a vanadium flow battery as part of the project 'Characterisation of Vanadium Batteries' (ForskEl project 6555) with the partners PA Energy A/S and OI Electric A/S under the Danish PSO energy research program. A 15kW/120kWh vanadium battery has been installed as part of the distributed energy systems experimental facility, SYSLAB, at Risoe DTU. A test programme has been carried out to get hands-on experience with the technology, to characterize the battery from a power system point of view and to assess it with respect to integration of wind energy in the Danish power system. The battery has been in operation for 18 months. During time of operation the battery has not shown signs of degradation of performance. It has a round-trip efficiency at full load of approximately 60% (depending on temperature and SOC). The sources of the losses are power conversion in cell stacks/electrolyte, power converter, and auxiliary power consumption from pumps and controller. The response time for the battery is limited at 20kW/s by the ramp rate of the power converter. The battery can thus provide power and frequency support for the power system. Vanadium battery is a potential technology for storage based services to the power system provided investment and O and M cost are low enough and long term operation is documented. (Author)

  14. The electron distribution in vanadium

    International Nuclear Information System (INIS)

    Weiss, R.J.

    1978-01-01

    It is shown that the apparent discrepancy for b.c.c. vanadium metal between the charge density and small momentum density anisotropies can be resolved by contracting the 3d triply-degenerate radial wavefunctions which point towards the nearest neighbours and expanding the 3d doubly-degenerate radial wave-functions which point towards the second-nearest neighbours. (author)

  15. Quantitative LIBS analysis of vanadium in samples of hexagonal mesoporous silica catalysts.

    Science.gov (United States)

    Pouzar, Miloslav; Kratochvíl, Tomás; Capek, Libor; Smoláková, Lucie; Cernohorský, Tomás; Krejcová, Anna; Hromádko, Ludek

    2011-02-15

    The method for the analysis of vanadium in hexagonal mesoporous silica (V-HMS) catalysts using Laser Induced Breakdown Spectrometry (LIBS) was suggested. Commercially available LIBS spectrometer was calibrated with the aid of authentic V-HMS samples previously analyzed by ICP OES after microwave digestion. Deposition of the sample on the surface of adhesive tape was adopted as a sample preparation method. Strong matrix effect connected with the catalyst preparation technique (1st vanadium added in the process of HMS synthesis, 2nd already synthesised silica matrix was impregnated by vanadium) was observed. The concentration range of V in the set of nine calibration standards was 1.3-4.5% (w/w). Limit of detection was 0.13% (w/w) and it was calculated as a triple standard deviation from five replicated determinations of vanadium in the real sample with a very low vanadium concentration. Comparable results of LIBS and ED XRF were obtained if the same set of standards was used for calibration of both methods and vanadium was measured in the same type of real samples. LIBS calibration constructed using V-HMS-impregnated samples failed for measuring of V-HMS-synthesized samples. LIBS measurements seem to be strongly influenced with different chemical forms of vanadium in impregnated and synthesised samples. The combination of LIBS and ED XRF is able to provide new information about measured samples (in our case for example about procedure of catalyst preparation). Copyright © 2010 Elsevier B.V. All rights reserved.

  16. Oxidation phase growth diagram of vanadium oxides film fabricated by rapid thermal annealing

    Institute of Scientific and Technical Information of China (English)

    Tamura KOZO; Zheng-cao LI; Yu-quan WANG; Jie NI; Yin HU; Zheng-jun ZHANG

    2009-01-01

    Thermal evaporation deposited vanadium oxide films were annealed in air by rapid thermal annealing (RTP). By adjusting the annealing temperature and time, a series of vanadium oxide films with various oxidation phases and surface morphologies were fabricated, and an oxidation phase growth diagram was established. It was observed that different oxidation phases appear at a limited and continuous annealing condition range, and the morphologic changes are related to the oxidation process.

  17. Investigation of vanadium and nitride alloys thin layers deposited by PVD

    Directory of Open Access Journals (Sweden)

    Nouveau C.

    2012-06-01

    Full Text Available In this work we present the technique of magnetron vapor deposition and the effect of several deposition parameters on the structural and morphological properties of prepared thin films. It was noted that the deposition time has an effect on the crystallinity, mechanical properties such as residual stress, roughness surface and the layer composition from target products. Studies were carried out on layers of vanadium (V and the nitride vanadium (VN.

  18. Swelling and tensile properties of neutron-irradiated vanadium alloys

    International Nuclear Information System (INIS)

    Loomis, B.A.; Smith, D.L.

    1990-07-01

    Vanadium-base alloys are candidates for use as structural material in magnetic fusion reactors. In comparison to other candidate structural materials (e.g., Type 316 stainless and HT-9 ferritic steels), vanadium-base alloys such as V-15Cr-5Ti and V-20Ti have intrinsically lower long-term neutron activation, neutron irradiation after-heat, biological hazard potential, and neutron-induced helium and hydrogen transmutation rates. Moreover, vanadium-base alloys can withstand a higher surface-heat, flux than steels because of their lower thermal stress factor. In addition to having these favorable neutronic and physical properties, a candidate alloy for use as structural material in a fusion reactor must have dimensional stability, i.e., swelling resistance, and resistance to embrittlement during the reactor lifetime at a level of structural strength commensurate with the reactor operating temperature and structural loads. In this paper, we present experimental results on the swelling and tensile properties of several vanadium-base alloys after irradiation at 420, 520, and 600 degree C to neutron fluences ranging from 0.3 to 1.9 x 10 27 neutrons/m 2 (17 to 114 atom displacements per atom [dpa])

  19. Effectively suppressing vanadium permeation in vanadium redox flow battery application with modified Nafion membrane with nacre-like nanoarchitectures

    Science.gov (United States)

    Zhang, Lesi; Ling, Ling; Xiao, Min; Han, Dongmei; Wang, Shuanjin; Meng, Yuezhong

    2017-06-01

    A novel self-assembled composite membrane, Nafion-[PDDA/ZrP]n with nacre-like nanostructures was successfully fabricated by a layer-by-layer (LbL) method and used as proton exchange membrane for vanadium redox flow battery applications. Poly(diallyldimethylammonium chloride) (PDDA) with positive charges and zirconium phosphate (ZrP) nanosheets with negative charges can form ultra-thin nacre-like nanostructure on the surface of Nafion membrane via the ionic crosslinking of tightly folded macromolecules. The lamellar structure of ZrP nanosheets and Donnan exclusion effect of PDDA can greatly decrease the vanadium ion permeability and improve the selectivity of proton conductivity. The fabricated Nafion-[PDDA/ZrP]4 membrane shows two orders of magnitude lower vanadium ion permeability (1.05 × 10-6 cm2 min-1) and 12 times higher ion selectivity than those of pristine Nafion membrane at room temperature. Consequently, the performance of vanadium redox flow batteries (VRFBs) assembled with Nafion-[PDDA/ZrP]3 membrane achieved a highly coulombic efficiency (CE) and energy efficiency (EE) together with a very slow self-discharge rate. When comparing with pristine Nafion VRFB, the CE and EE values of Nafion-[PDDA/ZrP]3 VRFB are 10% and 7% higher at 30 mA cm-2, respectively.

  20. Leaching characteristics of vanadium in mine tailings and soils near a vanadium titanomagnetite mining site

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jinyan; Tang, Ya; Yang, Kai [College of Architecture and Environment, Sichuan University, Chengdu 610065 (China); Rouff, Ashaki A. [School of Earth and Environmental Sciences, Queens College City University of New York, 65-30 Kissena Boulevard, Flushing, NY 11367 (United States); Elzinga, Evert J. [Department of Earth and Environmental Sciences, Rutgers University, Newark, NJ (United States); Huang, Jen-How, E-mail: jen-how.huang@unibas.ch [Institute of Environmental Geosciences, University of Basel, CH-4056 Basel (Switzerland)

    2014-01-15

    Highlights: • Vanadium in the soil and mine tailings has low solubility. • The leachability of vanadium in the mine tailings is lower than in the soil. • Low risk of vanadium migrating from the soil and mine tailings into the surrounding environment. • Drought and rewetting increase vanadium release from the soil and mine tailings. • Soil leaching processes control vanadium transport in soils overlain with mine tailings. -- Abstract: A series of column leaching experiments were performed to understand the leaching behaviour and the potential environmental risk of vanadium in a Panzhihua soil and vanadium titanomagnetite mine tailings. Results from sequential extraction experiments indicated that the mobility of vanadium in both the soil and the mine tailings was low, with <1% of the total vanadium readily mobilised. Column experiments revealed that only <0.1% of vanadium in the soil and mine tailing was leachable. The vanadium concentrations in the soil leachates did not vary considerably, but decreased with the leachate volume in the mine tailing leachates. This suggests that there was a smaller pool of leachable vanadium in the mine tailings compared to that in the soil. Drought and rewetting increased the vanadium concentrations in the soil and mine tailing leachates from 20 μg L{sup −1} to 50–90 μg L{sup −1}, indicating the potential for high vanadium release following periods of drought. Experiments with soil columns overlain with 4, 8 and 20% volume mine tailings/volume soil exhibited very similar vanadium leaching behaviour. These results suggest that the transport of vanadium to the subsurface is controlled primarily by the leaching processes occurring in soils.

  1. Directed synthesis of bio-inorganic vanadium oxide composites using genetically modified filamentous phage

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Michael; Baik, Seungyun [Environmental Safety Group, Korea Institute of Science and Technology Europe (KIST-Europe) Forschungsgesellschaft mbH, Campus E 7 1, Saarbruecken (Germany); Jeon, Hojeong; Kim, Yuchan [Center for Biomaterials, Biomedical Research Institute Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Kim, Jungtae [Environmental Safety Group, Korea Institute of Science and Technology Europe (KIST-Europe) Forschungsgesellschaft mbH, Campus E 7 1, Saarbruecken (Germany); Kim, Young Jun, E-mail: youngjunkim@kist-europe.de [Environmental Safety Group, Korea Institute of Science and Technology Europe (KIST-Europe) Forschungsgesellschaft mbH, Campus E 7 1, Saarbruecken (Germany)

    2015-05-15

    Highlights: • Phage is an excellent seeding for bio-templates for environmentally benign vanadium oxide nanocomposite synthesis. • The synthesized bio-inorganic vanadium oxide showed photodegradation activities. • The fabricated wt phage/vanadium oxide composite exhibited bundle-like structure. • The fabricated RSTB-phage/vanadium oxide composite exhibited a ball with a fiber-like nanostructure. • The virus/vanadium oxide composite could be applied in photocatalysts, sensors and nanoelectronic applications. - Abstract: The growth of crystalline vanadium oxide using a filamentous bacteriophage template was investigated using sequential incubation in a V{sub 2}O{sub 5} precursor. Using the genetic modification of the bacteriophage, we displayed two cysteines that constrained the RSTB-1 peptide on the major coat protein P8, resulting in vanadium oxide crystallization. The phage-driven vanadium oxide crystals with different topologies, microstructures, photodegradation and vanadium oxide composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), quartz microbalance and dissipation (QCM-D) and X-ray photoelectron spectroscopy (XPS). Non-specific electrostatic attraction between a wild-type phage (wt-phage) and vanadium cations in the V{sub 2}O{sub 5} precursor caused phage agglomeration and fiber formation along the length of the viral scaffold. As a result, the addition of recombinant phage (re-phage) in V{sub 2}O{sub 5} precursors formed heterogeneous structures, which led to efficient condensation of vanadium oxide crystal formation in lines, shown by QCM-D analysis. Furthermore, re-phage/V{sub x}O{sub x} composites showed significantly enhanced photodegradation activities compared with the synthesized wt-phage-V{sub 2}O{sub 5} composite under illumination. This study demonstrates that peptide-mediated vanadium oxide mineralization is governed by a complicated interplay of peptide sequence, local structure

  2. Permeation of deuterium implanted into vanadium alloys

    International Nuclear Information System (INIS)

    Anderl, R.A.; Longhurst, G.R.; Struttmann, D.A.

    1986-05-01

    Permeation of deuterium through the vanadium alloy, V-15Cr-5Ti, was investigated using 3-keV, D 3 + ion beams from a small accelerator. The experiments consisted of measurements of the deuterium reemission and permeation rates as a function of implantation fluence for 0.5-mm thick specimens heated to tempertures from 623 to 823 0 K. Implantation-side surface characterization was made by simultaneous measurements of sputtered ions with a secondary ion mass spectrometer (SIMS). Analyses of these measurements indicate that for the experimental conditions used, the steady-state deuterium permeation flux in V-15Cr-5Ti is approximately 18% of the implantation flux. This corresponds to approximately 1000 times that seen in the ferritic steel, HT-9, under comparable conditions. Measurement of deuterium diffusivity in V-15Cr-5Ti using permeation break-through times indicates D = 1.4 x 10 -8 exp(-.11 eV/kT) (m 2 /s)

  3. Analysis of molybdenum, tungsten, and vanadium in surface water of the Atlantic Ocean using solid phase extraction with 8-hydroxyquinoline and ICP MS determination

    Science.gov (United States)

    Rimskaya-Korsakova, M. N.; Berezhnaya, E. D.; Dubinin, A. V.

    2017-07-01

    An analytical technique is proposed to determine ultratrace concentrations of Mo, V, and W found in seawater using mass spectrometry with inductively coupled plasma (ICP MS) after preliminary concentration by solid-phase extraction of metal complexes with 8-hydroxyquinoline (8-HQ) on C18 octadecyl silica. The technique utilizes 150 mL of a water sample. A preconcentration factor 50 is obtained. The detection limits are 0.25 nmol/kg, 0.041 nmol/kg, and 5 pmol/kg for Mo, V, and W, respectively. Dissolved Mo, V, and Wconcentrations in surface seawater from Atlantic Ocean transect were determined. The concentrations ranges along the transect were: 91-108 nmol/kg for Mo, 28-35 nmol/kg for V, and 55-75 pmol/kg for W. The Mo/W ratio varied from 1300 to 1800.

  4. Investigation of structural, morphological and electrical properties of APCVD vanadium oxide thin films

    International Nuclear Information System (INIS)

    Papadimitropoulos, Georgios; Trantalidis, Stelios; Tsiatouras, Athanasios; Vasilopoulou, Maria; Davazoglou, Dimitrios; Kostis, Ioannis

    2015-01-01

    Vanadium oxide films were chemically vapor deposited (CVD) on oxidized Si substrates covered with CVD tungsten (W) thin films and on glass substrates covered with indium tin oxide (ITO) films, using vanadium(V) oxy-tri-isopropoxide (C 9 H 21 O 4 V) vapors. X-ray diffraction (XRD) measurements showed that the deposited films were composed of a mixture of vanadium oxides; the composition was determined mainly by the deposition temperature and less by the precursor temperature. At temperatures up to 450 C the films were mostly composed by monoclinic VO 2 . Other peaks corresponding to various vanadium oxides were also observed. X-ray microanalysis confirmed the composition of the films. The surface morphology was studied with atomic force microscopy (AFM) and scanning electron microscopy (SEM). These measurements revealed that the morphology strongly depends on the used substrate and the deposition conditions. The well-known metal-insulator transition was observed near 75 C for films mostly composed by monoclinic VO 2 . Films deposited at 450 C exhibited two transitions one near 50 C and the other near 60 C possibly related to the presence of other vanadium phases or of important stresses in them. Finally, the vanadium oxide thin films exhibited significant sensory capabilities decreasing their resistance in the presence of hydrogen gas with response times in the order of a few seconds and working temperature at 40 C. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Sol-gel growth of vanadium dioxide

    International Nuclear Information System (INIS)

    Speck, K.R.

    1990-01-01

    This thesis examines the chemical reactivity of vanadium (IV) tetrakis(t-butoxide) as a precursor for the sol-gel synthesis of vanadium dioxide. Hydrolysis and condensation of the alkoxide was studied by FTIR spectroscopy. Chemical modification of the vanadium tetraalkoxide by alcohol interchange was studied using 51 V NMR and FTIR. Vanadium dioxide thin films and powders were made from vanadium tetrakis(t-butoxide) by standard sol-gel techniques. Post-deposition heating under nitrogen was necessary to transform amorphous gels into vanadium dioxide. Crystallization of films and powders was studied by FTIR, DSC, TGA, and XRD. Gel-derived vanadium dioxide films undergo a reversible semiconductor-to-metal phase transition near 68C, exhibiting characteristic resistive and spectral changes. The electrical resistance decreased by two to three orders of magnitude and the infrared transmission sharply dropped as the material was cycled through this thermally induced phase transition. The sol-gel method was also used to make doped vanadium dioxide films. Films were doped with tungsten and molybdenum ions to effectively lower the temperature at which the transition occurs

  6. Peculiarities of powder metallurgy of vanadium and its alloys

    International Nuclear Information System (INIS)

    Radomysel'skij, I.D.; Solntsev, V.P.; Evtushenko, O.V.

    1987-01-01

    Literature data on preparation of vanadium powder and powder materials on the vanadium base are generalized. Application of powder metallurgy engineering, allowing simulaneously to introduce practically any strengthening and solid-lubricating components as well as to alloy vanadium, permits undoubtedly to develop composite materials on the vanadium base

  7. Tritium removal using vanadium hydride

    International Nuclear Information System (INIS)

    Hill, F.B.; Wong, Y.W.; Chan, Y.N.

    1978-01-01

    The results of an initial examination of the feasibility of separation of tritium from gaseous protium-tritium mixtures using vanadium hydride in cyclic processes is reported. Interest was drawn to the vanadium-hydrogen system because of the so-called inverse isotope effect exhibited by this system. Thus the tritide is more stable than the protide, a fact which makes the system attractive for removal of tritium from a mixture in which the light isotope predominates. The initial results of three phases of the research program are reported, dealing with studies of the equilibrium and kinetics properties of isotope exchange, development of an equilibrium theory of isotope separation via heatless adsorption, and experiments on the performance of a single heatless adsorption stage. In the equilibrium and kinetics studies, measurements were made of pressure-composition isotherms, the HT--H 2 separation factors and rates of HT--H 2 exchange. This information was used to evaluate constants in the theory and to understand the performance of the heatless adsorption experiments. A recently developed equilibrium theory of heatless adsorption was applied to the HT--H 2 separation using vanadium hydride. Using the theory it was predicted that no separation would occur by pressure cycling wholly within the β phase but that separation would occur by cycling between the β and γ phases and using high purge-to-feed ratios. Heatless adsorption experiments conducted within the β phase led to inverse separations rather than no separation. A kinetic isotope effect may be responsible. Cycling between the β and γ phases led to separation but not to the predicted complete removal of HT from the product stream, possibly because of finite rates of exchange. Further experimental and theoretical work is suggested which may ultimately make possible assessment of the feasibility and practicability of hydrogen isotope separation by this approach

  8. Absorption of hydrogen in vanadium, enhanced by ion bombardment; Ionenbeschussunterstuetzte Absorption des Wasserstoffs in Vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Paulus, H.; Lammers, M. [Inst. fuer Technologie- und Wissenstransfer, Soest (Germany); Mueller, K.H. [Inst. fuer Technologie- und Wissenstransfer, Soest (Germany)]|[Paderborn Univ. (Gesamthochschule), Soest (Germany). Fachbereich 16 - Elektrische Energietechnik; Kiss, G.; Kemeny, Z. [Technical Univ. Budapest (Hungary)

    1998-12-31

    Prior to hydrogen implantation into vanadium, the vanadium specimen usually is exposed to an activation process and is then heated at 1 atm hydrogen to temperatures between 500 and 600 C, subsequently cooled down in several steps. Within this temperature range, hydrogen solubility increases with declining temperature. A decisive factor determining hydrogen absorption is the fact that at temperatures above 250 C, oxygen desorbs from the material surface and thus no longer inhibits hydrogen absorption. Therefore a different approach was chosen for the experiments reported: Hydrogen absorption under UHV conditions at room temperature. After the usual activation process, the vanadium surface was cleaned by 5 keV Ar{sup +} ion bombardment. Thus oxygen absorption at the specimen surface (and new reactions with oxygen from the remaining gas) could be avoided, or removed. By means of thermal desorption mass spectrometry (TDMS), hydrogen absorption as a function of argon ion dose was analysed. TDMS measurements performed for specimens treated by ion bombardment prior to H{sup 2} exposure showed two H{sup 2} desorption peaks, in contrast to the profiles measured with specimens not exposed to ion bombardment. It is assumed that the ion bombardment disturbs the crystal structure so that further sites for hydrogen absorption are produced. (orig./CB) [Deutsch] Bei der Beladung von Vandium mit Wasserstoff wird ueblicherweise die Probe nach einer Aktivierungsprozedur bei 1 atm Wasserstoff auf Temperaturen im Bereich von 500 bis 600 C hochgeheizt und danach schrittweise abgekuehlt. In diesem Temperaturbereich nimmt die Wasserstoffloeslichkeit mit abnehmender Temperatur zu. Entscheidend fuer die Beladung ist aber auch die Tatsache, dass bei Temperaturen groesser 250 C Sauerstoff von der Oberflaeche desorbiert und dadurch die Absorption von Wasserstoff nicht mehr blockieren kann. Im Rahmen der hier beschriebenen Untersuchungen sollte die Wasserstoffbeladung unter UHV-Bedingungen bei

  9. Methods for making lithium vanadium oxide electrode materials

    Science.gov (United States)

    Schutts, Scott M.; Kinney, Robert J.

    2000-01-01

    A method of making vanadium oxide formulations is presented. In one method of preparing lithium vanadium oxide for use as an electrode material, the method involves: admixing a particulate form of a lithium compound and a particulate form of a vanadium compound; jet milling the particulate admixture of the lithium and vanadium compounds; and heating the jet milled particulate admixture at a temperature below the melting temperature of the admixture to form lithium vanadium oxide.

  10. Stress induced reorientation of vanadium hydride

    International Nuclear Information System (INIS)

    Beardsley, M.B.

    1977-10-01

    The critical stress for the reorientation of vanadium hydride was determined for the temperature range 180 0 to 280 0 K using flat tensile samples containing 50 to 500 ppM hydrogen by weight. The critical stress was observed to vary from a half to a third of the macroscopic yield stress of pure vanadium over the temperature range. The vanadium hydride could not be stress induced to precipitate above its stress-free precipitation temperature by uniaxial tensile stresses or triaxial tensile stresses induced by a notch

  11. A vanadium alloy for the application in a liquid metal blanket of a fusion reactor

    Science.gov (United States)

    Borgstedt, H. U.; Grundmann, M.; Konys, J.; Perić, Z.

    1988-07-01

    The vanadium alloy V3Ti1Si has been corrosion tested in liquid lithium and the eutectic alloy Pb-17Li at 550°C. This alloy has a comparable corrosion resistance to the alloy V15Cr5Ti in lithium. In this molten metal it is superior to stainless steel AISI 316. In the Pb-17Li melt it is even superior to martensitic steels. The alloy has only a weak tendency to be dissolved. It is sensitive to an exchange of non-metallic elements, which causes the formation of a hardened surface layer. These chemical effects are influenced by the mass and surface ratios of the vanadium alloy to the molten metals and other structural materials. These ratios are unfavorable in the two test loops. The effects might be less pronounced in a vanadium alloy/liquid metal fusion reactor blanket.

  12. Vanadium Bioleaching Behavior by Acidithiobacillus ferrooxidans from a Vanadium-Bearing Shale

    Directory of Open Access Journals (Sweden)

    Dunpei Wei

    2018-01-01

    Full Text Available This study investigated bioleaching behavior of vanadium from a vanadium-bearing shale using Acidithiobacillus ferrooxidans (A. ferrooxidans. Results showed a maximum recovery of 62% vanadium in 1.2-day bioleaching, which was 22.45% higher than the controls. Then, the vanadium leaching efficiency decreased significantly, only 24% of that was obtained on the tenth day. The vanadium extraction in 1.2 days was mainly attributed to the dissolution of vanadium in free oxides of shale. Fe3+ produced by A. ferrooxidans promoted the dissolution process. X-ray diffraction (XRD patterns of the leached residues confirmed the generation of jarosite. SEM-EDS analysis of the residues indicated that jarosite adsorbed on the shale and inhibited the further dissolution of vanadium. The relevance of V, Fe, S, O was quite good in the energy disperse X-ray spectrometry (EDS element mapping of jarosite, and acid-washing of the jarosite resulted in 31.6% of the vanadium in the precipitates desorption, indicating that the decrease of vanadium leaching efficiency in bioleaching process was caused by both adsorption and co-precipitation with jarosite.

  13. Vanadium carbide coatings: deposition process and properties

    International Nuclear Information System (INIS)

    Borisova, A.; Borisov, Y.; Shavlovsky, E.; Mits, I.; Castermans, L.; Jongbloed, R.

    2001-01-01

    Vanadium carbide coatings on carbon and alloyed steels were produced by the method of diffusion saturation from the borax melt. Thickness of the vanadium carbide layer was 5-15 μm, depending upon the steel grade and diffusion saturation parameters. Microhardness was 20000-28000 MPa and wear resistance of the coatings under conditions of end face friction without lubrication against a mating body of WC-2Co was 15-20 times as high as that of boride coatings. Vanadium carbide coatings can operate in air at a temperature of up to 400 o C. They improve fatigue strength of carbon steels and decrease the rate of corrosion in sea and fresh water and in acid solutions. The use of vanadium carbide coatings for hardening of various types of tools, including cutting tools, allows their service life to be extended by a factor of 3 to 30. (author)

  14. High temperature creep of vanadium

    International Nuclear Information System (INIS)

    Juhasz, A.; Kovacs, I.

    1978-01-01

    The creep behaviour of polycrystalline vanadium of 99.7% purity has been investigated in the temperature range 790-880 0 C in a high temperature microscope. It was found that the creep properties depend strongly on the history of the sample. To take this fact into account some additional properties such as the dependence of the yield stress and the microhardness on the pre-annealing treatment have also been studied. Samples used in creep measurements were selected on the basis of their microhardness. The activation energy of creep depends on the microhardness and on the creep temperature. In samples annealed at 1250 0 C for one hour (HV=160 kgf mm -2 ) the rate of creep is controlled by vacancy diffusion in the temperature range 820-880 0 C with an activation energy of 78+-8 kcal mol -1 . (Auth.)

  15. Volume dependence of vanadium magnetism

    International Nuclear Information System (INIS)

    Elzain, M.E.

    1993-07-01

    The first principle discrete variational method in the spin polarized local density approximation is used to calculate the local properties of 15 atom clusters representing variable crystal size bcc vanadium. Four distinct magnetic configurations are recognized as the lattice constant varies from 5.4 to 8.4 (a.u.). At the lowest end the clusters are paramagnetic (PM) whereas at the upper end clusters are ferromagnetic (FM). In between antiferromagnetic couplings prevail. The local magnetic moment increases, in a fashion not unlike second order transitions, from zero in the PM range to non-zero values in the AFM region. Transitions between other phases are first order. The systematics of these transitions are ascribed to the general shape of the density of states. The contact magnetic hyperfine field, charge density and 3d partial occupations at the central sites are also calculated. (author). 14 refs, 3 figs, 1 tab

  16. Fatigue of vanadium--hydrogen alloys

    International Nuclear Information System (INIS)

    Lee, K.S.; Stoloff, N.S.

    1975-01-01

    Hydrogen contents near and above the room temperature solubility limit increase the high cycle fatigue life but decrease low cycle life of polycrystalline vanadium. Changes in endurance limit with hydrides may be a consequence of decreased cyclic strain hardening coefficient, n'. 132 ppM hydrogen in solution has only a slightly beneficial effect on stress controlled fatigue life and essentially no effect on low cycle fatigue life. Unalloyed vanadium exhibits profuse striations, while hydrides produce cleavage cracks in fatigued samples. 10 fig

  17. Electrochemical Oscillation of Vanadium Ions in Anolyte

    Directory of Open Access Journals (Sweden)

    Hao Peng

    2017-08-01

    Full Text Available Periodic electrochemical oscillation of the anolyte was reported for the first time in a simulated charging process of the vanadium redox flow batteries. The electrochemical oscillation could be explained in terms of the competition between the growth and the chemical dissolution of V2O5 film. Also, the oscillation phenomenon was possible to regular extra power consumption. The results of this paper might enable new methods to improve the charge efficiency and energy saving for vanadium redox flow batteries.

  18. Fabrication of vanadium cans for neutron diffraction experiments

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chin man; Baik, Sung Hoon; Park, Sun Kyu

    1999-12-01

    The laser weld technique of vanadium developed to experiment for neutron diffraction of HANARO. The demands for this laser welding technique were applied to process control in vanadium film welding and to fabricate various sizing vanadium cans. The vanadium can had a advantage to have less coherent in neutron. KAERI developed the fabrication jig of 6-12 mm diameter cans using 0.125 mm vanadium thin film, and investigated the laser welding procedure for making the various diameter and length of vanadium cans using the fabricated jigs and Nd:YAG laser. (author)

  19. Corrosion resistance investigation of vanadium alloys in liquid lithium

    Energy Technology Data Exchange (ETDEWEB)

    Borovitskaya, I. V., E-mail: symp@imet.ac.ru [Russian Academy of Sciences, Baikov Institute of Metallurgy and Materials Science (Russian Federation); Lyublinskiy, I. E. [JSC Red Star (Russian Federation); Bondarenko, G. G. [National Research University Higher School of Economics (Russian Federation); Paramonova, V. V. [Russian Academy of Sciences, Baikov Institute of Metallurgy and Materials Science (Russian Federation); Korshunov, S. N.; Mansurova, A. N. [National Research Center Kurchatov Institute (Russian Federation); Lyakhovitskiy, M. M. [Russian Academy of Sciences, Baikov Institute of Metallurgy and Materials Science (Russian Federation); Zharkov, M. Yu. [JSC Red Star (Russian Federation)

    2016-12-15

    A major concern in using vanadium alloys for first wall/blanket systems in fusion reactors is their activity with regard to nonmetallic impurities in the coolants. This paper presents the results of studying the corrosion resistance in high-purity liquid lithium (with the nitrogen and carbon content of less than 10{sup –3} wt %) of vanadium and vanadium alloys (V–1.86Ga, V–3.4Ga–0.62Si, V–4.81Ti–4.82Cr) both in the initial state and preliminarily irradiated with Ar+ ions with energy of 20 keV to a dose of 10{sup 22} m{sup –2} at an irradiation temperature of ~400°C. The degree of corrosion was estimated by measuring the changes in the weight and microhardness. Corrosion tests were carried out under static isothermal conditions at a temperature of 600°C for 400 h. The identity of corrosion mechanisms of materials both irradiated with Ar ions and not irradiated, which consisted in an insignificant penetration of nitrogen into the materials and a substantial escape of oxygen from the materials, causing the formation of a zone with a reduced microhardness near the surface, was established. The influence of the corrosive action of lithium on the surface morphology of the materials under study was found, resulting in the manifestation of grain boundaries and slip lines on the sample surface, the latter being most clearly observed in the case of preliminary irradiation with Ar ions.

  20. Improved capacitance characteristics of electrospun ACFs by pore size control and vanadium catalyst.

    Science.gov (United States)

    Im, Ji Sun; Woo, Sang-Wook; Jung, Min-Jung; Lee, Young-Seak

    2008-11-01

    Nano-sized carbon fibers were prepared by using electrospinning, and their electrochemical properties were investigated as a possible electrode material for use as an electric double-layer capacitor (EDLC). To improve the electrode capacitance of EDLC, we implemented a three-step optimization. First, metal catalyst was introduced into the carbon fibers due to the excellent conductivity of metal. Vanadium pentoxide was used because it could be converted to vanadium for improved conductivity as the pore structure develops during the carbonization step. Vanadium catalyst was well dispersed in the carbon fibers, improving the capacitance of the electrode. Second, pore-size development was manipulated to obtain small mesopore sizes ranging from 2 to 5 nm. Through chemical activation, carbon fibers with controlled pore sizes were prepared with a high specific surface and pore volume, and their pore structure was investigated by using a BET apparatus. Finally, polyacrylonitrile was used as a carbon precursor to enrich for nitrogen content in the final product because nitrogen is known to improve electrode capacitance. Ultimately, the electrospun activated carbon fibers containing vanadium show improved functionality in charge/discharge, cyclic voltammetry, and specific capacitance compared with other samples because of an optimal combination of vanadium, nitrogen, and fixed pore structures.

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

    International Nuclear Information System (INIS)

    Schacht, L.; Navarrete, J.; Schacht, P.; Ramirez, M. 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 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)

  2. 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)

  3. Formation of electrically insulating coatings on aluminided vanadium-base alloys in liquid lithium

    International Nuclear Information System (INIS)

    Park, J.H.; Dragel, G.

    1993-01-01

    Aluminide coatings were produced on vanadium and vanadium-base alloys by exposure of the materials to liquid lithium that contained 3-5 at.% dissolved aluminum in sealed capsules at temperatures between 775 and 880 degrees C. Reaction of the aluminide layer with dissolved nitrogen in liquid lithium provides a means of developing an in-situ electrical insulator coating on the surface of the alloys. The electrical resistivity of A1N coatings on aluminided V and V-20 wt.% Ti was determined in-situ

  4. Vacancy distribution in nonstoichiometric vanadium monoxide

    International Nuclear Information System (INIS)

    Gusev, A.I.; Davydov, D.A.; Valeeva, A.A.

    2011-01-01

    Graphical abstract: Display Omitted Research highlights: → A certain fraction of vanadium atoms in disordered cubic vanadium monoxide VO y and ordered tetragonal phase V 52 O 64 is located in tetrahedral positions of a basic cubic lattice. → These positions are never occupied by any atoms in other strongly nonstoichiometric carbides, nitrides and oxides. → Both disordered and ordered structures of vanadium monoxide are characterized by the presence of short-range order of displacements in the oxygen sublattice and short-range order of substitution in the metal sublattice. → The short-range order of displacement is caused by the local displacements of O atoms from V (t) atoms occupying tetrahedral positions. The short-range order of substitution appears because V (t) atoms in the tetrahedral positions are always in the environment of four vacancies □ of the vanadium sublattice. - Abstract: Structural vacancy distribution in the crystal lattice of the tetragonal V 52 O 64 superstructure which is formed on the basis of disordered superstoichiometric cubic vanadium monoxide VO y ≡V x O z is experimentally determined and the presence of significant local atomic displacements and large local microstrains in a crystal lattice of real ordered phase is established. It is shown that the relaxation of local microstrains takes place owing to the basic disordered cubic phase grain refinement and a formation of ordered phase domains. The ordered phase domains grow in the direction from the boundaries to the centre of grains of the disordered basic cubic phase. Isothermal evolution at 970 K of the average domain size in ordered VO 1.29 vanadium monoxide is established. It is shown that the short-range order presents in a metal sublattice of disordered cubic VO y vanadium monoxide. The character of the short-range order is such that vanadium atoms occupying tetrahedral positions are in the environment of four vacant sites of the vanadium sublattice. This means that the

  5. APS- and XPS-investigations of vanadium, vanadium carbide and graphite

    Energy Technology Data Exchange (ETDEWEB)

    Bradshaw, A M; Krause, U [Technische Univ. Muenchen (F.R. Germany). Inst. fuer Physikalische Chemie und Theoretische Chemie

    1975-11-01

    Soft X-ray appearance potential spectroscopy (APS) and X-ray photoelectron spectroscopy (XPS) have been used to study vanadium, vanadium carbide, and graphite. The chemical shifts for vanadium carbide with respect to metallic vanadium and graphite are compared for the two methods. The Csub(K) structure in APS and the valence band in XPS for vanadium carbide show good agreement with the band structure calculations of Neckel and co-workers. Using the band structure calculations of Painter et al. it is also shown how the multi-peak structure in the APS spectrum of graphite is possibly due to density of states effects. It would therefore appear that plasmon coupling plays only a minor role.

  6. NEXAFS characterization and reactivity studies of bimetallic vanadium molybdenum oxynitride hydrotreating catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kapoor, R.; Oyama, S.T. [Virginia Polytechnic Inst., Blacksburg, VA (United States); Fruehberger, B.; Chen, J.G. [Exxon Research and Engineering Company, Annandale, NJ (United States)

    1997-02-27

    The surface and bulk compositions of vanadium molybdenum oxynitride (V{sub 2}MoO{sub 1.7}N{sub 2.4}), prepared by temperature-programmed reaction (TPR) of vanadium molybdenum oxide (V{sub 2}MoO{sub 8}) with ammonia, have been characterized using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The NEXAFS data were recorded at the K-edges of nitrogen and oxygen, the L-edge of vanadium, and the M-edge of molybdenum. The nitrogen K-edge region of V-Mo oxynitride shows the characteristic NEXAFS features of early-transition-metal nitrides, although these features are different from those of either VN or Mo{sub 2}N. Furthermore, comparison of the electron yield and fluorescence yield measurements also reveals that the oxidation state is different for vanadium near the surface region and for vanadium in the bulk, which is estimated to be 2.8 {+-} 0.3 and 3.8 {+-} 0.3, respectively. The oxidation state of bulk molybdenum is also estimated to be 4.4 {+-} 0.3. The X-ray diffraction pattern shows that the bulk phase of the bimetallic oxide is different from the pure monometallic oxide phases but the oxynitride has a cubic structure that resembles the pure vanadium and molybdenum nitride phases. The V-Mo oxide as prepared shows a preferential orientation of [001] crystallographic planes which is lost during the nitridation process. This shows that the solid state transformation V{sub 2}MoO{sub 8} {yields} V{sub 2}MoO{sub 1.7}N{sub 2.4} is not topotactic. 27 refs., 8 figs., 1 tab.

  7. Manufacturing development of low activation vanadium alloys

    International Nuclear Information System (INIS)

    Smith, J.P.; Johnson, W.R.; Baxi, C.B.

    1996-10-01

    General Atomics is developing manufacturing methods for vanadium alloys as part of a program to encourage the development of low activation alloys for fusion use. The culmination of the program is the fabrication and installation of a vanadium alloy structure in the DIII-D tokamak as part of the Radiative Divertor modification. Water-cooled vanadium alloy components will comprise a portion of the new upper divertor structure. The first step, procuring the material for this program has been completed. The largest heat of vanadium alloy made to date, 1200 kg of V-4Cr-4Ti, has been produced and is being converted into various product forms. Results of many tests on the material during the manufacturing process are reported. Research into potential fabrication methods has been and continues to be performed along with the assessment of manufacturing processes particularly in the area of joining. Joining of vanadium alloys has been identified as the most critical fabrication issue for their use in the Radiative Divertor Program. Joining processes under evaluation include resistance seam, electrodischarge (stud), friction and electron beam welding. Results of welding tests are reported. Metallography and mechanical tests are used to evaluate the weld samples. The need for a protective atmosphere during different welding processes is also being determined. General Atomics has also designed, manufactured, and will be testing a helium-cooled, high heat flux component to assess the use of helium cooled vanadium alloy components for advanced tokamak systems. The component is made from vanadium alloy tubing, machined to enhance the heat transfer characteristics, and joined to end flanges to allow connection to the helium supply. Results are reported

  8. Study of propane partial oxidation on vanadium-containing catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Komashko, G.A.; Khalamejda, S.V.; Zazhigalov, V.A. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fizicheskoj Khimii

    1998-12-31

    The present results indicate that maximum selectivity to acrylic acid can be reached over V-P-Zr-O catalysts. When the hydrocarbon concentration is 5.1 vol.% the selectivity is about 30% at quite high paraffin conversion. Conclusively, some explanations to the observed facts can be given. The V-P-O catalyst promotion with lanthanum by means of mechanochemical treatment is distinguished by the additive uniform spreading all over the matrix surface. Such twophase system is highly active in propane conversion (lanthanum oxide) and further oxidation of the desired products. The similar properties are attributed to V-P-Bi-La-O catalyst. Bismuth, tellurium and zirconium additives having clearly defined acidic properties provoke the surface acidity strengthening and make easier desorption of the acidic product (acrylic acid) from the surface lowering its further oxidation. Additionally, since bismuth and zirconium are able to form phosphates and, according to, to create space limitations for the paraffin molecule movement out of the active group boundaries, this can be one more support in favour of the selectivity increase. With this point of view very interesting results were obtained. It has been shown that the more limited the size of the vanadium unit, the higher the selectivity is. Monoclinic phase AV{sub 2}P{sub 2}O{sub 10} which consists in clusters of four vanadium atoms is sensibly more reactive than the orthorhombic phase consists in V{sub {infinity}} infinite chains. (orig.)

  9. Iron diminishes the in vitro biological effect of vanadium.

    Science.gov (United States)

    Mechanistic pathways underlying inflammatory injury following exposures to vanadium-containing compounds are not defined. We tested the postulate that the in vitro biological effect of vanadium results from its impact on iron homeostasis. Human bronchial epithelial (HBE) cells ex...

  10. Decomposition of hydrogen peroxide on nickel oxide - vanadium pentoxide catalysts and the effect of ionizing radiation on them

    International Nuclear Information System (INIS)

    Mucka, V.

    1984-01-01

    Some physico-chemical and catalytic properties of nickel oxide-vanadium pentoxide two-component catalysts were studied over the entire concentration range of the components, using the decomposition of hydrogen peroxide in an aqueous solution as the test reaction. The two oxides were found to affect each other; this was shown by the dependences of the specific surface area, the V 4+ ion concentration, and the catalyst activity on the system composition. At low vanadium pentoxide concentrations (up to 15 mol%) the reaction took place on nickel oxide modified with vanadium pentoxide, whereas in the region of higher vanadium pentoxide concentrations the decomposition of the peroxide was catalyzed primarily in the homogeneous phase by vanadium(V) peroxide ions; in a sample with 30 mol% V 2 O 5 , trivalent vanadium also played a part. With catalysts obtained by mere mechanical mixing of the two oxides, a modified activity was observed in the region of high excess of nickel oxide. The activity of catalyst, particularly pure nickel oxide, was increased by its partial reduction and decreased by its exposure to gamma radiation if the dose was higher than 10 5 Gy. The effects observed are interpreted in terms of the concept of bivalent catalytic centres. (author)

  11. Investigation of local environments in Nafion-SiO(2) composite membranes used in vanadium redox flow batteries.

    Science.gov (United States)

    Vijayakumar, M; Schwenzer, Birgit; Kim, Soowhan; Yang, Zhenguo; Thevuthasan, S; Liu, Jun; Graff, Gordon L; Hu, Jianzhi

    2012-04-01

    Proton conducting polymer composite membranes are of technological interest in many energy devices such as fuel cells and redox flow batteries. In particular, polymer composite membranes, such as SiO(2) incorporated Nafion membranes, are recently reported as highly promising for the use in redox flow batteries. However, there is conflicting reports regarding the performance of this type of Nafion-SiO(2) composite membrane in the redox flow cell. This paper presents results of the analysis of the Nafion-SiO(2) composite membrane used in a vanadium redox flow battery by nuclear magnetic resonance (NMR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier Transform Infra Red (FTIR) spectroscopy, and ultraviolet-visible spectroscopy. The XPS study reveals the chemical identity and environment of vanadium cations accumulated at the surface. On the other hand, the (19)F and (29)Si NMR measurement explores the nature of the interaction between the silica particles, Nafion side chains and diffused vanadium cations. The (29)Si NMR shows that the silica particles interact via hydrogen bonds with the sulfonic groups of Nafion and the diffused vanadium cations. Based on these spectroscopic studies, the chemical environment of the silica particles inside the Nafion membrane and their interaction with diffusing vanadium cations during flow cell operations are discussed. This study discusses the origin of performance degradation of the Nafion-SiO(2) composite membrane materials in vanadium redox flow batteries. Copyright © 2011 Elsevier Inc. All rights reserved.

  12. Optical spectra of vanadium (5, 4) compounds during extraction by di-2-ethylhexylphosphoric acid

    International Nuclear Information System (INIS)

    Kurbatova, L.D.; Medvedeva, N.I.

    2000-01-01

    Optical spectra of vanadium (5, 4) complexes with HDEHP are studied using literature data on quantum-chemical calculations of vanadium (5) and vanadium (4) oxides. Extraction of vanadium is conducted by undiluted HDEHP from sulfuric acid solutions. Absorption electron spectra (AES) of vanadium (5), vanadium (4) and vanadium (5, 4) compounds are presented. In AES of vanadium (5, 4) four absorption bands at 24000, 17000, 14500 and 13500 cm -1 appear. Comparison with spectra of vanadium (5) and vanadium (4) shows that band 17000 cm -1 which appears only during mutual extraction of vanadium (5) and vanadium (4) is caused by transitions appearing between filled and empty levels of d-zone broadened by vanadium (5) and vanadium (4) interaction [ru

  13. Nature of active vanadium nanospecies in MCM-41 type catalysts for olefins oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Chanquía, Corina M., E-mail: cchanquia@cab.cnea.gov.ar [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CAB-CNEA). Av. Bustillo 9500, R8402AGP, San Carlos de Bariloche, Río Negro (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); Cánepa, Analía L. [Centro de Investigación y Tecnología Química (CITeQ), Universidad Tecnológica Nacional, Facultad Regional Córdoba (UTN-FRC), Maestro López esq. Cruz Roja Argentina, Ciudad Universitaria, 5016, Córdoba Capital (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); Winkler, Elin L. [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CAB-CNEA). Av. Bustillo 9500, R8402AGP, San Carlos de Bariloche, Río Negro (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); and others

    2016-06-01

    A multi-technique physicochemical investigation including UV–Vis-DRS, Raman spectroscopy, XPS, ESR and FTIRS with pyridine adsorption was performed to analyze the nature of different vanadium nanospecies present on MCM-41 type catalysts. By employing a direct hydrothermal synthesis, vanadium species were incorporated into siliceous structure mainly as tetrahedrally coordinated isolated V{sup δ+} ions, which would be located inside the wall and on the wall surface of the mesoporous channels. The coexistence of both vanadium oxidation states V{sup 4+} and V{sup 5+} was also revealed. Acidity measurements permitted to infer about the majority presence of Lewis acid sites, which increase with vanadium content. The catalytic performance of these materials was evaluated in the reaction of α-pinene oxidation with H{sub 2}O{sub 2}. The highest intrinsic activity of the sample with lower V loading was attributed to the high dispersion and efficiency of the isolated V{sup δ+} species that actuate as active sites. A mixture of reaction products arising from competitive processes of epoxidation and allylic oxidation was found. - Highlights: • Nature of vanadium nanospecies in mesoporous silicates was investigated. • From hydrothermal sol–gel synthesis, isolated V{sup δ+} sites were mainly generated. • The coexistence of both vanadium oxidation states V{sup 4+} and V{sup 5+} was revealed. • The catalytic performance was evaluated in α-pinene oxidation with H{sub 2}O{sub 2}. • The high catalytic activity is attributed to high dispersion of isolated V{sup δ+} ions.

  14. Corrosion control of vanadium in aqueous solutions by amino acids

    International Nuclear Information System (INIS)

    El-Rabiee, M.M.; Helal, N.H.; El-Hafez, Gh.M. Abd; Badawy, W.A.

    2008-01-01

    The electrochemical behavior of vanadium in amino acid free and amino acid containing aqueous solutions of different pH was studied using open-circuit potential measurements, polarization techniques and electrochemical impedance spectroscopy (EIS). The corrosion current density, i corr , the corrosion potential, E corr and the corrosion resistance, R corr , were calculated. A group of amino acids, namely, glycine, alanine, valine, histidine, glutamic and cysteine has been investigated as environmentally safe inhibitors. The effect of Cl - on the corrosion inhibition efficiency especially in acid solutions was investigated. In neutral and basic solutions, the presence of amino acids increases the corrosion resistance of the metal. The electrochemical behavior of V before and after the corrosion inhibition process has shown that some amino acids like glutamic acid and histidine have promising corrosion inhibition efficiency at low concentration (≅25 mM). The inhibition efficiency (η) was found to depend on the structure of the amino acid and the constituents of the corrosive medium. The corrosion inhibition process is based on the adsorption of the amino acid molecules on the metal surface and the adsorption process follows the Freundlich isotherm. The adsorption free energy for valine on V in acidic solutions was found to be -9.4 kJ/mol which reveals strong physical adsorption of the amino acid molecules on the vanadium surface

  15. Thermal conductivity of high purity vanadium

    International Nuclear Information System (INIS)

    Jung, W.D.

    1975-01-01

    The thermal conductivity, Seebeck coefficient, and electrical resistivity of four high-purity vanadium samples were measured over the temperature range 5 to 300 0 K. The highest purity sample had a resistance ratio (rho 273 /rho 4 . 2 ) of 1524. The highest purity sample had a thermal conductivity maximum of 920 W/mK at 9 0 K and had a thermal conductivity of 35 W/mK at room temperature. At low temperatures, the thermal resistivity was limited by the scattering of electrons by impurities and phonons. The thermal resistivity of vanadium departed from Matthiessen's rule at low temperatures. The electrical resistivity and Seebeck coefficient of high purity vanadium showed no anomalous behavior above 130 0 K. The intrinsic electrical resistivity at low temperatures was due primarily to interband scattering of electrons. The Seebeck coefficient was positive from 10 to 240 0 K and had a maximum which was dependent upon sample purity

  16. Transformation and precipitation in vanadium treated steels

    Science.gov (United States)

    Vassiliou, Andreas D.

    A series of carbon manganese steels containing varying amounts of carbon, vanadium and nitrogen was investigated in relation to the solubility of VC and VN in austenite, the grain coarsening characteristics of austenite, the tempering of martensite and other structures, the transformation during continuous cooling, the effect of vanadium addition and increasing nitrogen content on the thermo-mechanical processing of austenite, and the transformation of various morphologies of austenite to ferrite.The sites for preferential nucleation and growth of ferrite were identified and the effect of ferrite grain size inhomogeneity was investigated with a view to minimising it.The C/N ratio in the V(CN) precipitates was largely controlled by C/N ratio in the steel and it was also influenced by the austenitising treatment. As expected, the solubility of VN was less than that of VC.A systematic investigation of austenitising time and temperature on the grain coarsening characteristics was carried out showing the effects of vanadium, carbon and nitrogen. It was tentatively suggested that C-C and N-N clustering in the vanadium free steels controlled the grain growth whereas in the presence of vanadium, it was shown that VN and VC pinned the austenite grain boundaries and restricted grain growth. However coarsening or solution of VC and VN allowed the grain bondaries to migrate and grain coarsening occurred. The grain coarsening temperature was controlled predominantly by VN, whilst the VC dissolved frequently below the grain coarsening temperature.In the as quenched martensite, increasing nitrogen progressively increased the as quenched hardness, and the hardness also greatly increased with increasing carbon and vanadium added together. Examining the precipitation strengthening in tempered martensite showed that in the absence of vanadium, martensite softened progressively with increasing temperature and time. Vanadium additions increased the hardness level during low temperature

  17. Positron lifetime in vanadium oxide bronzes

    International Nuclear Information System (INIS)

    Dryzek, J.; Dryzek, E.

    2003-01-01

    The positron lifetime (PL) and Doppler broadening (DB) of annihilation line measurements have been performed in vanadium oxide bronzes M x V 2 O 5 . The dependence of these annihilation characteristics on the kind and concentration of the metal M donor has been observed. In the PL spectrum only one lifetime component has been detected in all studied bronzes. The results indicate the positron localization in the structural tunnels present in the crystalline lattice of the vanadium oxide bronzes. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Vanadium alloys for fusion reactor applications

    International Nuclear Information System (INIS)

    Mattas, R.F.; Loomis, B.A.; Smith, D.L.

    1992-01-01

    This paper reports that fusion reactors will produce a severe operating environment for structural materials. The material should have good mechanical strength and ductility to high temperature, be corrosion resistant to the local environment, have attractive thermophysical properties to accommodate high heat loads, and be resistant to neutron damage. Vanadium alloys are being developed for such applications, and they exhibit desirable properties in many areas Recent progress in vanadium alloy development indicates good strength and ductility to 700 degrees C, minimal degradation by neutron irradiation, and reduced radioactivity compared with other candidate alloy systems

  19. Vanadium recycling in the United States in 2004

    Science.gov (United States)

    Goonan, Thomas G.

    2011-01-01

    As one of a series of reports that describe the recycling of metal commodities in the United States, this report discusses the flow of vanadium in the U.S. economy in 2004. This report includes a description of vanadium supply and demand in the United States and illustrates the extent of vanadium recycling and recycling trends. In 2004, apparent vanadium consumption, by end use, in the United States was 3,820 metric tons (t) in steelmaking and 232 t in manufacturing, of which 17 t was for the production of superalloys and 215 t was for the production of other alloys, cast iron, catalysts, and chemicals. Vanadium use in steel is almost entirely dissipative because recovery of vanadium from steel scrap is chemically impeded under the oxidizing conditions in steelmaking furnaces. The greatest amount of vanadium recycling is in the superalloy, other-alloy, and catalyst sectors of the vanadium market. Vanadium-bearing catalysts are associated with hydrocarbon recovery and refining in the oil industry. In 2004, 2,850 t of vanadium contained in alloy scrap and spent catalysts was recycled, which amounted to about 44 percent of U.S. domestic production. About 94 percent of vanadium use in the United States was dissipative (3,820 t in steel/4,050 t in steel+fabricated products).

  20. Vanadium bioavailability in soils amended with blast furnace slag

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Maja A., E-mail: maja.larsson@slu.se [Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, 750 07 Uppsala (Sweden); Baken, Stijn, E-mail: stijn.baken@ees.kuleuven.be [Department of Earth and Environmental Sciences, Leuven University, Kasteelpark Arenberg 20 bus 2459, 3001 Leuven (Belgium); Smolders, Erik, E-mail: erik.smolders@ees.kuleuven.be [Department of Earth and Environmental Sciences, Leuven University, Kasteelpark Arenberg 20 bus 2459, 3001 Leuven (Belgium); Cubadda, Francesco, E-mail: francesco.cubadda@iss.it [Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, Rome 00161 (Italy); Gustafsson, Jon Petter, E-mail: jon-petter.gustafsson@slu.se [Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, 750 07 Uppsala (Sweden); Division of Land and Water Resources Engineering, KTH Royal Institute of Technology, Brinellvägen 28, 100 44 Stockholm (Sweden)

    2015-10-15

    Blast furnace (BF) slags are commonly applied as soil amendments and in road fill material. In Sweden they are also naturally high in vanadium. The aim of this study was to assess the vanadium bioavailability in BF slags when applied to soil. Two soils were amended with up to 29% BF slag (containing 800 mg V kg{sup −1}) and equilibrated outdoors for 10 months before conducting a barley shoot growth assay. Additional soil samples were spiked with dissolved vanadate(V) for which assays were conducted two weeks (freshly spiked) and 10 months (aged) after spiking. The BF slag vanadium was dominated by vanadium(III) as shown by V K-edge XANES spectroscopy. In contrast, results obtained by HPLC-ICP-MS showed that vanadium(V), the most toxic vanadium species, was predominant in the soil solution. Barley shoot growth was not affected by the BF slag additions. This was likely due to limited dissolution of vanadium from the BF slag, preventing an increase of dissolved vanadium above toxic thresholds. The difference in vanadium bioavailability among treatments was explained by the vanadium concentration in the soil solution. It was concluded that the vanadium in BF slag is sparingly available. These findings should be of importance in environmental risk assessment.

  1. Extraction-complexonometric determination of vanadium(4) in the presence of vanadium(3)

    International Nuclear Information System (INIS)

    Gordeeva, M.N.; Ryndina, A.M.; Stanevich, T.V.

    1976-01-01

    The extraction-complexonometric method has been investigated for determining vanadium(4) in the presence of vanadium (3) with high contents of these forms in the solution analyzed. The method of separation of V(4) and V(3) is based on extraction of the ion acetate of vanadium(4) with eriochrome red B(ERCB) and diphenyl quanidinium (DPG) by a mixture of chloroform and isoamyl alcohol (3:1). To control the content of V(4) and V(3) the method of reciprocal complexonometric titration is used (the titrating solution was a solution of thorium nitride, and xylenol orange was a solution of thorium nitride, and xylenol orange was used as metal indicator). Titration has been carried out in an acid solution at pH=2.8. The developed method has been applied to analysis of lithium-zinc spinels containing both forms of vanadium

  2. Aqueous vanadium ion dynamics relevant to bioinorganic chemistry: A review.

    Science.gov (United States)

    Kustin, Kenneth

    2015-06-01

    Aqueous solutions of the four highest vanadium oxidation states exhibit four diverse colors, which only hint at the diverse reactions that these ions can undergo. Cationic vanadium ions form complexes with ligands; anionic vanadium ions form complexes with ligands and self-react to form isopolyanions. All vanadium species undergo oxidation-reduction reactions. With a few exceptions, elucidation of the dynamics of these reactions awaited the development of fast reaction techniques before the kinetics of elementary ligation, condensation, reduction, and oxidation of the aqueous vanadium ions could be investigated. As the biological roles played by endogenous and therapeutic vanadium expand, it is appropriate to bring the results of the diverse kinetics studies under one umbrella. To achieve this goal this review presents a systematic examination of elementary aqueous vanadium ion dynamics. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Corrosion of vanadium and V 3Ti 1Si in flowing lithium

    International Nuclear Information System (INIS)

    Konys, J.

    1986-01-01

    A pumped Li loop fabricated from a titanium stabilized Type 316 steel was designed and constructed. At temperatures of about 823 K, experiments over a duration of more than 7500 h were performed. A magnetic trap had to be incorporated just before the flowmeter to avoid the precipitation of magnetic particles. Therefore it was possible to investigate the influence of the magnetic trap on the corrosion behaviour of V in flowing Li. The results are as follows: - The corrosion rate of V is about 14 μm/year and independent of the nitrogen content of Li. The corrosion rate of V 3Ti 1Si depends on the N concentration of Li. At about 30 wppm N in Li a vanadium-titanium-nitride is formed at the surface of the specimens. Hence, a low rate of 4 μm/year can be stated. - Both materials pick-up more N than C from Li, pure vanadium double as much nitrogen as the alloy V 3Ti 1Si. - N diffuses into the bulk of both materials, whilst C is bound near the surface. The hardening at the surface is due to the up-take of N. - The vanadium-carbonitride-, respectively the vanadium-titanium-nitride-layers have a strong influence on the weight loss and the up-take of non-metals. - The magnetic trap reduces the weight loss of vanadium in a significant way. The positive influence of the magnetic trap is supposed to be due to the reduction of the nitrogen content of Li. - The corrosion rates of the alloy V 3Ti 1Si show, that the dissolution due to V loss does not affect the lifetime of the alloy. The comparison with steels and nickle-base-alloys demonstrates the advantages of this material. Nevertheless, the purification of the Li and the control of its nonmetal-levels is indispensable. (orig./HP) [de

  4. Thermodynamics of oxygen in solid solution in vanadium and niobium--vanadium alloys

    International Nuclear Information System (INIS)

    Steckel, G.L.

    1977-01-01

    A thermodynamic study was made of the vanadium-oxygen and niobium-vanadium-oxygen systems utilizing the solid state galvanic cell technique. Investigations were made with a ThO 2 /Y 2 O 3 electrolyte over the temperature ranges 700 to 1200 0 C (973 to 1473 K) for the binary system and 650 to 1150 0 C (923 to 1423 K) for the ternary system. The activity of oxygen in vanadium obeys Henry's law for the temperatures of this investigation for concentrations up to 3.2 at. percent oxygen. For higher concentrations the activity coefficient shows positive deviations from Henry's law. The terminal solubility of oxygen in vanadium was determined. The activity of oxygen in Nb--V alloys obeys Henry's law for the temperatures of this study for oxygen concentrations less than approximately 2 at. percent. For certain Nb/V ratios Henry's law is obeyed for concentrations as high as 6.5 at. percent oxygen. First order entropy and enthalpy interaction coefficients have been determined to describe the effect on the oxygen activity of niobium additions to vanadium-rich alloys with dilute oxygen concentrations. Niobium causes relatively small decreases in the oxygen activity of V-rich alloys and increases the oxygen solubility limit. Vanadium additions to Nb-rich alloys also increases the oxygen solubility and causes substantial decreases in the dilute solution oxygen activities. The change in the thermodynamic properties when molecular oxygen dissolves in vanadium and niobium--vanadium alloys and the equilibrium oxygen pressure over the binary and ternary systems were also determined

  5. A method for recovery of iron, titanium, and vanadium from vanadium-bearing titanomagnetite

    Science.gov (United States)

    Zhang, Yi-min; Wang, Li-na; Chen, De-sheng; Wang, Wei-jing; Liu, Ya-hui; Zhao, Hong-xin; Qi, Tao

    2018-02-01

    An innovative method for recovering valuable elements from vanadium-bearing titanomagnetite is proposed. This method involves two procedures: low-temperature roasting of vanadium-bearing titanomagnetite and water leaching of roasting slag. During the roasting process, the reduction of iron oxides to metallic iron, the sodium oxidation of vanadium oxides to water-soluble sodium vanadate, and the smelting separation of metallic iron and slag were accomplished simultaneously. Optimal roasting conditions for iron/slag separation were achieved with a mixture thickness of 42.5 mm, a roasting temperature of 1200°C, a residence time of 2 h, a molar ratio of C/O of 1.7, and a sodium carbonate addition of 70wt%, as well as with the use of anthracite as a reductant. Under the optimal conditions, 93.67% iron from the raw ore was recovered in the form of iron nugget with 95.44% iron grade. After a water leaching process, 85.61% of the vanadium from the roasting slag was leached, confirming the sodium oxidation of most of the vanadium oxides to water-soluble sodium vanadate during the roasting process. The total recoveries of iron, vanadium, and titanium were 93.67%, 72.68%, and 99.72%, respectively.

  6. Vanadium Electrolyte Studies for the Vanadium Redox Battery-A Review.

    Science.gov (United States)

    Skyllas-Kazacos, Maria; Cao, Liuyue; Kazacos, Michael; Kausar, Nadeem; Mousa, Asem

    2016-07-07

    The electrolyte is one of the most important components of the vanadium redox flow battery and its properties will affect cell performance and behavior in addition to the overall battery cost. Vanadium exists in several oxidation states with significantly different half-cell potentials that can produce practical cell voltages. It is thus possible to use the same element in both half-cells and thereby eliminate problems of cross-contamination inherent in all other flow battery chemistries. Electrolyte properties vary with supporting electrolyte composition, state-of-charge, and temperature and this will impact on the characteristics, behavior, and performance of the vanadium battery in practical applications. This Review provides a broad overview of the physical properties and characteristics of the vanadium battery electrolyte under different conditions, together with a description of some of the processing methods that have been developed to produce vanadium electrolytes for vanadium redox flow battery applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Atomic layer deposition of VO{sub 2} films with Tetrakis-dimethyl-amino vanadium (IV) as vanadium precursor

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Xinrui [Key Laboratory of Inorganic Coating Materials CAS, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Cao, Yunzhen, E-mail: yzhcao@mail.sic.ac.cn [Key Laboratory of Inorganic Coating Materials CAS, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800 (China); Yan, Lu; Li, Ying; Song, Lixin [Key Laboratory of Inorganic Coating Materials CAS, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2017-02-28

    Highlights: • VO{sub 2} film was easily deposited by ALD using novel vanadium precursor V(NMe{sub 2}){sub 4}. • Deposition and annealing condition were systematically investigated. • Comparable transition properties of VO{sub 2} film on resistance and spectral transmittance were studied. - Abstract: VO{sub 2} thin films have been grown on Si(100) (VO{sub 2}/Si) and fused silica substrates (VO{sub 2}/SiO{sub 2}) by atomic layer deposition (ALD) using tetrakis-dimethyl-amino vanadium (IV) (TDMAV) as a novel vanadium precursor and water as reactant gas. The quartz crystal microbalance (QCM) measurement was performed to study the ALD process of VO{sub 2} thin film deposition, and a constant growth rate of about 0.95 Å/cycle was obtained at the temperature range of 150–200 °C. XRD measurement was performed to study the influence of deposition temperature and post-annealing condition on the crystallization of VO{sub 2} films, which indicated that the films deposited between 150 and 200 °C showed well crystallinity after annealing at 475 °C for 100 min in Ar atmosphere. XPS measurement verified that the vanadium oxidation state was 4+ for both as-deposited film and post-annealed VO{sub 2}/Si film. AFM was applied to study the surface morphology of VO{sub 2}/Si films, which showed a dense polycrystalline film with roughness of about 1 nm. The resistance of VO{sub 2}/Si films deposited between 150 °C and 200 °C as a function of temperature showed similar semiconductor-to-metal transition (SMT) characters with the transition temperature for heating branch (T{sub c,h}) of about 72 °C, a hysteresis width of about 10 °C and the resistance change of two orders of magnitude. The increase of T{sub c,h} compared with the bulk VO{sub 2} (68 °C) may be attributed to the tensile stress along the c-axis in the film. Transmittance measurement of VO{sub 2}/SiO{sub 2} films showed typical thermochromic property with a NIR switching efficiency of above 50% at 2 μm across

  8. Synthesis and characterization of new vanadium salcylaldoxime ...

    African Journals Online (AJOL)

    ilyasblk

    The elemental microanalysis and mass spectra (electrospray method) were carried out ... The 51V NMR spectra were measured in D2O or in DMSO-d6, using VOCl as the .... These signals are in the range reported for the vanadium atoms in a ...

  9. Determination of Leachable Vanadium (V) in Sediment

    African Journals Online (AJOL)

    NICO

    KEYWORDS. Certified reference materials, vanadium(+5) speciation, electrothermal atomic absorption spectrometry. 1. Introduction. The measurement of the chemical species of elements, instead of the total element concentration, has become an irreversible trend in analytical chemistry.1–2 The motivation lies in the fact.

  10. Structure and function of vanadium haloperoxidases

    NARCIS (Netherlands)

    Wever, R.; Michibata, H.

    2012-01-01

    Vanadium haloperoxidases contain the bare metal oxide vanadate as a prosthetic group and differ strongly from the heme peroxidases in substrate specificity and molecular properties. The substrates of these enzymes are limited to halides and sulfides, which in the presence of hydrogen peroxide are

  11. Vanadium supply and demand outlook. Final report

    International Nuclear Information System (INIS)

    1978-01-01

    A review has been made of the reserves and resources for vanadium minerals in the United States and foreign countries. Foreign sources are presently used to provide a substantial part of national demand because of price advantages. There are so many functioning foreign sources for vanadium that it is difficult to conceive of circumstances that would shut all of them off. The basis for the national stockpile is described. A recommendation is made to add the 65V-35Al alloy as a component of the stockpile for titanium alloy production in a national emergency. Estimated consumption growth rates to 1990 vary from one to five percent per year depending on the end product involved. Fission reactor use of vanadium-base alloys has not developed because of technical problems. In the chemical field, a slow steady growth of five to six percent per year is projected. Technical preferences for vanadium in various steel applications will continue although other alloying alternatives are generally available. Overall environmental effects do not appear to be a serious industrial problem

  12. Fundamental irradiation studies on vanadium alloys

    International Nuclear Information System (INIS)

    Loomis, B.A.; Garner, F.A.; Ermi, A.M.

    1985-05-01

    A joint experiment on the irradiation response of simple vanadium alloys has been initiated under the auspices of the DAFS and BES progams. Specimen fabrication is nearly complete and the alloys are expected to be irradiated in lithium in FFTF-MOTA Cycles 7 and 8

  13. Lithium insertion in sputtered vanadium oxide film

    DEFF Research Database (Denmark)

    West, K.; Zachau-Christiansen, B.; Skaarup, S.V.

    1992-01-01

    were oxygen deficient compared to V2O5. Films prepared in pure argon were reduced to V(4) or lower. The vanadium oxide films were tested in solid-state lithium cells. Films sputtered in oxygen showed electrochemical properties similar to crystalline V2O5. The main differences are a decreased capacity...

  14. Oxidative Stress as a Mechanism Involved in Kidney Damage After Subchronic Exposure to Vanadium Inhalation and Oral Sweetened Beverages in a Mouse Model.

    Science.gov (United States)

    Espinosa-Zurutuza, Maribel; González-Villalva, Adriana; Albarrán-Alonso, Juan Carlos; Colín-Barenque, Laura; Bizarro-Nevares, Patricia; Rojas-Lemus, Marcela; López-Valdéz, Nelly; Fortoul, Teresa I

    Kidney diseases have notably increased in the last few years. This is partially explained by the increase in metabolic syndrome, diabetes, and systemic blood hypertension. However, there is a segment of the population that has neither of the previous risk factors, yet suffers kidney damage. Exposure to atmospheric pollutants has been suggested as a possible risk factor. Air-suspended particles carry on their surface a variety of fuel combustion-related residues such as metals, and vanadium is one of these. Vanadium might produce oxidative stress resulting in the damage of some organs such as the kidney. Additionally, in countries like Mexico, the ingestion of sweetened beverages is a major issue; whether these beverages alone are responsible for direct kidney damage or whether their ingestion promotes the progression of an existing renal damage generates controversy. In this study, we report the combined effect of vanadium inhalation and sweetened beverages ingestion in a mouse model. Forty CD-1 male mice were distributed in 4 groups: control, vanadium inhalation, 30% sucrose in drinking water, and vanadium inhalation plus sucrose 30% in drinking water. Our results support that vanadium inhalation and the ingestion of 30% sucrose induce functional and histological kidney damage and an increase in oxidative stress biomarkers, which were higher in the combined effect of vanadium plus 30% sucrose. The results also support that the ingestion of 30% sucrose alone without hyperglycemia also produces kidney damage.

  15. In situ self-sacrificed template synthesis of vanadium nitride/nitrogen-doped graphene nanocomposites for electrochemical capacitors.

    Science.gov (United States)

    Liu, Hong-Hui; Zhang, Hong-Ling; Xu, Hong-Bin; Lou, Tai-Ping; Sui, Zhi-Tong; Zhang, Yi

    2018-03-15

    Vanadium nitride and graphene have been widely used as pseudo-capacitive and electric double-layer capacitor electrode materials for electrochemical capacitors, respectively. However, the poor cycling stability of vanadium nitride and the low capacitance of graphene impeded their practical applications. Herein, we demonstrated an in situ self-sacrificed template method for the synthesis of vanadium nitride/nitrogen-doped graphene (VN/NGr) nanocomposites by the pyrolysis of a mixture of dicyandiamide, glucose, and NH 4 VO 3 . Vanadium nitride nanoparticles of the size in the range of 2 to 7 nm were uniformly embedded into the nitrogen-doped graphene skeleton. Furthermore, the VN/NGr nanocomposites with a high specific surface area and pore volume showed a high specific capacitance of 255 F g -1 at 10 mV s -1 , and an excellent cycling stability (94% capacitance retention after 2000 cycles). The excellent capacitive properties were ascribed to the excellent conductivity of nitrogen-doped graphene, high surface area, high pore volume, and the synergistic effect between vanadium nitride and nitrogen-doped graphene.

  16. Partial Oxidation of n-Butane over a Sol-Gel Prepared Vanadium Phosphorous Oxide

    Directory of Open Access Journals (Sweden)

    Juan M. Salazar

    2013-01-01

    Full Text Available Vanadium phosphorous oxide (VPO is traditionally manufactured from solid vanadium oxides by synthesizing VOHPO4∙0.5H2O (the precursor followed by in situ activation to produce (VO2P2O7 (the active phase. This paper discusses an alternative synthesis method based on sol-gel techniques. Vanadium (V triisopropoxide oxide was reacted with ortho-phosphoric acid in an aprotic solvent. The products were dried at high pressure in an autoclave with a controlled excess of solvent. This procedure produced a gel of VOPO4 with interlayer entrapped molecules. The surface area of the obtained materials was between 50 and 120 m2/g. Alcohol produced by the alkoxide hydrolysis reduced the vanadium during the drying step, thus VOPO4 was converted to the precursor. This procedure yielded non-agglomerated platelets, which were dehydrated and evaluated in a butane-air mixture. Catalysts were significantly more selective than the traditionally prepared materials with similar intrinsic activity. It is suggested that the small crystallite size obtained increased their selectivity towards maleic anhydride.

  17. Extraction of Vanadium from Vanadium Slag Via Non-salt Roasting and Ammonium Oxalate Leaching

    Science.gov (United States)

    Li, Meng; Du, Hao; Zheng, Shili; Wang, Shaona; Zhang, Yang; Liu, Biao; Dreisinger, David Bruce; Zhang, Yi

    2017-10-01

    A clean method featuring non-salt roasting followed by (NH4)2C2O4 leaching to recover vanadium from vanadium slag was proposed. The carcinogenic Cr6+ compounds and exhaust gases were avoided, and the water generated from vanadate precipitation may be recycled and reused in this new leaching process. The leaching residues may be easily used by a blast furnace. Moreover, (NH4)2C2O4 solution was used as a leaching medium to avoid expensive and complicated ammonium controlling operations as a result of the stability of (NH4)2C2O4 at a high temperature. The transformation mechanisms of vanadium- and chromium-bearing phases were systematically investigated by x-ray diffraction analysis and scanning electron microscopy with energy-disperse x-ray spectrometry, respectively. In addition, the effects of oxygen concentration, roasting temperature, and holding time on vanadium recovery were investigated. Finally, the effects of leaching variables on the vanadium leaching rate were also examined.

  18. Vaporization study on vanadium monoxide and two-phase mixture of vanadium and vanadium monoxide by mass-spectrometric method

    International Nuclear Information System (INIS)

    Banchorndhevakul, W.; Matsui, Tsuneo; Naito, Keiji

    1986-01-01

    The vapor pressures over single phase vanadium monoxide VO 1.022 (s) and the two-phase mixture of vanadium metal (β phase) and vanadium monoxide were measured by mass-spectrometric method in the temperature range of 1,803 ∼ 1,990 and 1,703 ∼ 1,884 K, respectively. The main gas species over both systems were found to be VO(g) and V(g). The vapor pressure of VO(g) over the two-phase mixture of V(s) and VO(s) was a little lower than that over single phase VO(s). The vapor pressure of V(g) over the two-phase mixture was nearly equal to that over single phase. From the vapor pressure data, the enthalpies of vaporization, the enthalpies of formation for VO(g) and V(g) and the dissociation energy of VO(g) were determined. The oxygen partial pressure was calculated as a function of temperature from the vapor pressures of VO(g) and V(g), from which the partial molar enthalpies and entropies of oxygen in both systems were obtained. (author)

  19. Vanadium dioxide formed by the sol-gel process

    International Nuclear Information System (INIS)

    Potember, R.S.; Speck, K.R.; Hu, H.S.

    1990-01-01

    This patent describes a process for the deposition of a crystalline vanadium dioxide thin film. It comprises: providing a solution comprising a vanadium tetraalkoxide and solvent; allowing hydrolysis and condensation reactions to progressively form a homogeneous sol from the solution, applying a coating of the sol to the substrate; allowing a gel to form from the sol on the substrate by evaporating the solvent; dehydrating the gel by heat treatment under an inert atmosphere to form the crystalline vanadium dioxide film

  20. Effect of vanadium compounds on acid phosphatase activity

    OpenAIRE

    Vescina, Cecilia M.; Sálice, Viviana C.; Cortizo, Ana María; Etcheverry, Susana B.

    1996-01-01

    The direct effect of different vanadium compounds on acid phosphatase (ACP) activity was investigated. Vanadate and vanadyl but not pervanadate inhibited the wheat germ ACP activity. These vanadium derivatives did not alter the fibroblast Swiss 3T3 soluble fraction ACP activity. Using inhibitors of tyrosine phosphatases (PTPases), the wheat germ ACP was partially characterized as a PTPase. This study suggests that the inhibitory ability of different vanadium derivatives to modulate ACP activi...

  1. Oxidation of methyl heterocyclic compounds on vanadium oxide catalysts

    International Nuclear Information System (INIS)

    Shimanskaya, M.V.; Lejtis, L.A.; Iovel', I.G.; Gol'dberg, Yu.Sh.; Skolmejstere, R.A.; Golender, L.O.

    1985-01-01

    Data on vapor-phase oxidation of methyl derivatives of thiophene, Δ 2 - thiazo line, pyridine, pyrazine and pyramidine on oxide vanadium-molybdenum catalysts to corresponding heterylaldehydes are generalized. The dependence of catalytic properties of oxide vanadium-molybdenum systems in oxidation reactions of methylheterocyclic compounds on V:Mo ratio in the catalyst is revealed. It is shown that heterocyclic compounds are coordinated by a heteroatom on Lewis centres of V-Mo-O-catalyst primarily with partially reduced vanadium ions

  2. Analysis of molybdenum, chromium, vanadium and iron by polarographic techniques

    International Nuclear Information System (INIS)

    Al-Zand, T.K.

    1986-01-01

    The application of direct current Tast polarograph, differential pulse polarography and phase-selective alternative current Tast polarography to the problem of determining molybdenum, chromium, vanadium and iron in various supporting electrolytes is reported. The effect of the supporting electrolyte on the wave/peak potential and sensitivity of the metal ion have been examined. The polarographic methods were applied for simultaneous determination of chromium (3)/chromium (6), vanadium (4), vanadium (5) and iron (2)/iron (3) in different supporting electrolytes

  3. High rate capability of lithium/silver vanadium oxide cells

    International Nuclear Information System (INIS)

    Takeuchi, E.S.; Zelinsky, M.A.; Keister, P.

    1986-01-01

    High rate characteristics of the lithium/silver vanadium oxide system were investigated in test cells providing four different limiting surface areas. The cells were tested by constant current and constant resistance discharge with current densities ranging from 0.04 to 6.4 mA/cm/sup 2/. The maximum current density under constant resistance and constant current discharges which would deliver 50% of theoretical capacity was determined. The ability of the cells to deliver high current pulses was evaluated by application of 10 second pulses with current densities ranging from 3 to 30 mA/cm/sup 2/. The voltage delay characteristics of the cells were determined after 1 to 3 months of storage at open circuit voltage or under low level background currents. The volumetric and gravimetric energy density of the SVO system is compared to other cathode materials

  4. Vanadium Transitions in the Spectrum of Arcturus

    Science.gov (United States)

    Wood, M. P.; Sneden, C.; Lawler, J. E.; Den Hartog, E. A.; Cowan, J. J.; Nave, G.

    2018-02-01

    We derive a new abundance for vanadium in the bright, mildly metal-poor red giant Arcturus. This star has an excellent high-resolution spectral atlas and well-understood atmospheric parameters, and it displays a rich set of neutral vanadium lines that are available for abundance extraction. We employ a newly recorded set of laboratory FTS spectra to investigate any potential discrepancies in previously reported V I log(gf) values near 900 nm. These new spectra support our earlier laboratory transition data and the calibration method utilized in that study. We then perform a synthetic spectrum analysis of weak V I features in Arcturus, deriving log ε(V) = 3.54 ± 0.01 (σ = 0.04) from 55 lines. There are no significant abundance trends with wavelength, line strength, or lower excitation energy.

  5. Vanadium in fuel oil - a new solution

    Energy Technology Data Exchange (ETDEWEB)

    Czech, N. [Siemens, Muelheim (Germany); Finckh, H. [Siemens, Erlangen (Germany)

    1998-11-01

    Hot corrosion of the hot-gas-path components due to vanadium contamination is one of the hazards associated with heavy residual oil combustion in heavy-duty gas turbines. This economically attractive oil combustion process has benefited from the recently developed vanadium inhibition technique, which is currently being tested at the Valladolid 220 MWe combined cycle plant in Mexico. The method uses atomization of a dilute aqueous solution of Epsom salt (MgSO{sub 7},7H{sub 2}O) into very small droplets which are then injected onto the flame where intensive mixing takes place. The successful use of this new technique promises extended operating periods between cleanup operations, and cost reductions from the use of inexpensive materials, as well as the ability to operate advanced gas turbines on difficult fuels, not previously feasible. (UK)

  6. On the superconductivity of vanadium based alloys

    International Nuclear Information System (INIS)

    Brouers, F.; Rest, J. Van der

    1984-01-01

    The electron density of states of solid solutions of vanadium based transition metal alloys V 90 X 10 is computed with the aim of calculating the superconducting transition temperature using the McMillan formula. As observed experimentally for X on the left hand side of V in the periodic table, one obtains an increase of Tc while for X on the right hand side of V the critical temperature decreases. The detailed comparison with experiments indicate that when the bandwidths of the two constituents are different, one cannot neglect the variation of the electron-phonon interactions. Another important conclusion is that for alloys which are in the split-band limit like VAu, VPd and VPt, the agreement with experimental data can be obtained only by assuming that these alloys have a short-range order favouring clusters of pure vanadium. (Author) [pt

  7. Microadditions of boron and vanadium in ADI

    Directory of Open Access Journals (Sweden)

    Rzychoń T.

    2007-01-01

    Full Text Available In the second part of the study, describing the role of vanadium and boron microadditions in the process of structure formation in heavy-walled castings made from ADI, the results of own investigations were presented. Within this study two series of melts of the ductile iron were made, introducing microadditions of the above mentioned elements to both unalloyed ductile iron and the ductile iron containing high levels of nickel and copper (the composition typical of ADI. Melts were conducted with iron-nickel-magnesium master alloy. Thermal analysis of the solidification process of the cast keel blocks was conducted, the heat treatment of the alloys was carried out, and then the effect of the introduced additions of boron and vanadium on the hardenability of the investigated cast iron was examined and evaluated.

  8. Nitridation of vanadium by ion beam irradiation

    International Nuclear Information System (INIS)

    Kiuchi, Masato; Chayahara, Akiyoshi; Kinomura, Atsushi; Ensinger, Wolfgang

    1994-01-01

    The nitridation of vanadium by ion beam irradiation is studied by the ion implantation method and the dynamic mixing method. The nitrogen ion implantation was carried out into deposited V(110) films. Using both methods, three phases are formed, i.e. α-V, β-V 2 N, and δ-VN. Which phases are formed is related to the implantation dose or the arrival ratio. The orientation of the VN films produced by the dynamic ion beam mixing method is (100) and that of the VN films produced by the ion implantation method is (111). The nitridation of vanadium is also discussed in comparison with that of titanium and chromium. ((orig.))

  9. Mineralogy and geochemistry of vanadium in the Colorado Plateau

    Science.gov (United States)

    Weeks, A.D.

    1961-01-01

    The chief domestic source of vanadium is uraniferous sandstone in the Colorado Plateau. Vanadium is 3-, 4-, or 5-valent in nature and, as oxides or combined with other elements, it forms more than 40 minerals in the Plateau ores. These ores have been studied with regard to the relative amounts of vanadium silicates and oxide-vanadates, uranium-vanadium ratios, the progressive oxidation of black low-valent ores to high-valent carnotite-type ores, and theories of origin. ?? 1961.

  10. Effect of vanadium compounds on acid phosphatase activity.

    Science.gov (United States)

    Vescina, C M; Sálice, V C; Cortizo, A M; Etcheverry, S B

    1996-01-01

    The direct effect of different vanadium compounds on acid phosphatase (ACP) activity was investigated. Vanadate and vanadyl but not pervanadate inhibited the wheat germ ACP activity. These vanadium derivatives did not alter the fibroblast Swiss 3T3 soluble fraction ACP activity. Using inhibitors of tyrosine phosphatases (PTPases), the wheat germ ACP was partially characterized as a PTPase. This study suggests that the inhibitory ability of different vanadium derivatives to modulate ACP activity seems to depend on the geometry around the vanadium atom more than on the oxidation state. Our results indicate a correlation between the PTPase activity and the sensitivity to vanadate and vanadyl cation.

  11. Pepspectives of chlorine application in metallurgy of vanadium

    International Nuclear Information System (INIS)

    Korshunov, B.G.; Kutsenko, S.A.

    1983-01-01

    The most expedient variants of reprocessing of vanadium technical oxide (5), ferrovanadium and converter slags by chlorine technology with production of pure metal are considered. It is shown that production of vanadium by the way of electro- or metallothermal reduction of chlorides provides more plastic metal in comparison with reduction from oxides. The methods of production of VOCl 3 , VCl 4 and vanadium lowest chlorides are considered. Necessity of expansion of production of vanadium chlorine derivatives is dictated as well by their increasing application in different areas of national economy, in particular, as catalysts in organic synthesis

  12. Experimental method for investigating helium effects in irradiated vanadium

    International Nuclear Information System (INIS)

    Smith, D.L.; Matsui, H.; Greenwood, L.; Loomis, B.

    1987-10-01

    Analyses have been performed which indicate that an effective method for experimentally investigating helium effects in neutron irradiated vanadium base alloys can be developed. The experimental procedure involves only modest modifications to existing procedures currently used for irradiation testing of vanadium-base alloys in the FFTF reactor. Helium is generated in the vanadium alloy by decay of tritium which is either preinjected or generated within the test capsule. Calculations indicate that nearly constant He/dpa ratios of desired magnitude can be attained by proper selection of experimental parameters. The proposed method could have a major impact on the development of vanadium base alloys for fusion reactor applications. 8 refs., 4 figs

  13. Vanadium bioavailability and toxicity to soil microorganisms and plants.

    Science.gov (United States)

    Larsson, Maja A; Baken, Stijn; Gustafsson, Jon Petter; Hadialhejazi, Golshid; Smolders, Erik

    2013-10-01

    Vanadium, V, is a redox-sensitive metal that in solution, under aerobic conditions, prevails as the oxyanion vanadate(V). There is little known regarding vanadium toxicity to soil biota, and the present study was set up to determine the toxicity of added vanadate to soil organisms and to investigate the relationship between toxicity and vanadium sorption in soils. Five soils with contrasting properties were spiked with 7 different doses (3.2-3200 mg V kg(-1)) of dissolved vanadate, and toxicity was measured with 2 microbial and 3 plant assays. The median effective concentration (EC50) thresholds of the microbial assays ranged from 28 mg added V kg(-1) to 690 mg added V kg(-1), and the EC50s in the plant assays ranged from 18 mg added V kg(-1) to 510 mg added V kg(-1). The lower thresholds were in the concentration range of the background vanadium in the untreated control soils (15-58 mg V kg(-1)). The vanadium toxicity to plants decreased with a stronger soil vanadium sorption strength. The EC50 values for plants expressed on a soil solution basis ranged from 0.8 mg V L(-1) to 15 mg V L(-1) and were less variable among soils than corresponding values based on total vanadium in soil. It is concluded that sorption decreases the toxicity of added vanadate and that soil solution vanadium is a more robust measure to determine critical vanadium concentrations across soils. © 2013 SETAC.

  14. Controlled synthesis and electrochemical properties of vanadium ...

    Indian Academy of Sciences (India)

    Vanadium oxides (V3O7·H2O and VO2) with different morphologies have been selectively synthesized ... appeared at around 68 ◦C. Furthermore, the electrochemical properties of V3O7·H2O nanobelts, VO2(B) .... morphologies of shape-controlled orthorhombic V3O7·H2O ..... condition, as shown in figures S14i and j.

  15. Characterization of vanadium flow battery. Revised

    Energy Technology Data Exchange (ETDEWEB)

    Bindner, H.; Ekman, C.; Gehrke, O.; Isleifsson, F.

    2011-02-15

    This report summarizes the work done at Risoe-DTU testing a vanadium flow battery as part of the project ''Characterisation of Vanadium Batteries'' (ForskEl project 6555) with the partners PA Energy A/S and OI Electric A/S under the Danish PSO energy research program. A 15kW/120kWh vanadium battery has been installed as part of the distributed energy systems experimental facility, SYSLAB, at Risoe DTU. A test programme has been carried out to get hands-on experience with the technology, to characterize the battery from a power system point of view and to assess it with respect to integration of wind energy in the Danish power system. The battery has been in operation for 18 months. During time of operation the battery has not shown signs of degradation of performance. It has a round-trip efficiency at full load of approximately 60% (depending on temperature and SOC). The sources of the losses are power conversion in cell stacks/electrolyte, power converter, and auxiliary power consumption from pumps and controller. The efficiency was not influenced by the cycling of the battery. The response time for the battery is limited at 20kW/s by the ramp rate of the power converter. The battery can thus provide power and frequency support for the power system. The battery was operated together with a 11kW stall-regulated Gaia wind turbine to smooth the output of the wind turbine and during the tests the battery proved capable of firming the output of the wind turbine. Vanadium battery is a potential technology for storage based services to the power system provided investment and O and M cost are low enough and long term operation is documented. (Author)

  16. Isotope mixtures of hydrogen in vanadium

    International Nuclear Information System (INIS)

    Mecking-Schloetensack, P.

    1982-03-01

    The properties of isotope-mixtures of Protium and Deuterium stored in Vanadium have been studied. Protium and Deuterium are existing as interstitial-atoms on tetrahedral sites as well as on octahedral sites in this system. This feature leads to large isotopic-effects between the two isotopes. The dependence of the thermodynamic functions like heat of solution, nonconfigurational entropy, specific heat and ordering temperatures from the composition of the isotope-mixture has been determined. (orig.)

  17. An extraction process to recover vanadium from low-grade vanadium-bearing titanomagnetite

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Desheng; Zhao, Hongxin; Hu, Guoping [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Qi, Tao, E-mail: tqgreen@ipe.ac.cn [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Yu, Hongdong; Zhang, Guozhi [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Lina, E-mail: linawang@ipe.ac.cn [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Weijing [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-08-30

    Highlights: • The leaching solution contains high concentration of acid, iron, impurities and lower vanadium. • 99.4% of vanadium and 4.2% of iron were extracted by three-stage extraction process. • 99.6% of vanadium and 5.4% of iron were stripped by three-stage stripping process. • The stripping solution contains 40.16 g/L V{sub 2}O{sub 5}, 0.691 g/L Fe, 0.007 g/L TiO{sub 2} and 0.247 g/L CaO. • The vanadium product of V{sub 2}O{sub 5} with purity of 99.12%, 0.026% Fe and well crystallized. - Abstract: An extraction process to recover vanadium from low-grade vanadium-bearing titanomagnetite was developed. In this study, a mixed solvent system of di(2-ethylhexyl) phosphate (D2EHPA) and tri-n-butyl phosphate (TBP) diluted with kerosene was used for the selective extraction of vanadium from a hydrochloric acid leaching solution that contained low vanadium concentration with high concentrations of iron and impurities of Ca, Mg, and Al. In the extraction process, the initial solution pH and the phase ratio had considerable functions in the extraction of vanadium from the hydrochloric acid leaching solution. Under optimal extraction conditions (i.e., 30–40 °C for 10 min, 1:3 phase ratio (O/A), 20% D2EHPA concentration (v/v), and 0–0.8 initial solution pH), 99.4% vanadium and only 4.2% iron were extracted by the three-stage counter-current extraction process. In the stripping process with H{sub 2}SO{sub 4} as the stripping agent and under optimal stripping conditions (i.e., 20% H{sub 2}SO{sub 4} concentration, 5:1 phase ratio (O/A), 20 min stripping time, and 40 °C stripping temperature), 99.6% vanadium and only 5.4% iron were stripped by the three-stage counter-current stripping process. The stripping solution contained 40.16 g/L V{sub 2}O{sub 5}, 0.691g/L Fe, 0.007 g/L TiO{sub 2}, 0.006 g/L SiO{sub 2} and 0.247 g/L CaO. A V{sub 2}O{sub 5} product with a purity of 99.12% V{sub 2}O{sub 5} and only 0.026% Fe was obtained after the oxidation, precipitation

  18. Vanadium pentoxide nanoparticles mimic vanadium haloperoxidases and thwart biofilm formation

    NARCIS (Netherlands)

    Natalio, F.; Andre, R.; Hartog, A.F.; Stoll, B.; Jochum, K.P.; Wever, R.; Tremel, W.

    2012-01-01

    Marine biofouling—the colonization of small marine microorganisms on surfaces that are directly exposed to seawater, such as ships' hulls—is an expensive problem that is currently without an environmentally compatible solution1. Biofouling leads to increased hydrodynamic drag, which, in turn, causes

  19. Effect of neutron irradiation on vanadium alloys

    International Nuclear Information System (INIS)

    Braski, D.N.

    1986-01-01

    Neutron-irradiated vanadium alloys were evaluated for their susceptibility to irradiation hardening, helium embrittlement, swelling, and residual radioactivity, and the results were compared with those for the austenitic and ferritic stainless steels. The VANSTAR-7 and V-15Cr-5Ti alloys showed the greatest hardening between 400 and 600 0 C while V-3Ti-1Si and V-20Ti had lower values that were comparable to those of ferritic steels. The V-15Cr-5Ti and VANSTAR-7 alloys were susceptible to helium embrittlement caused by the combination of weakened grain boundaries and irradiation-hardened grain matrices. Specimen fractures were entirely intergranular in the most severe instances of embrittlement. The V-3Ti-1Si and V-20Ti alloys were more resistant to helium embrittlement. Except for VANSTAR-7 irradiated to 40 dpa at 520 0 C, all of the vanadium alloys exhibited low swelling that was similar to the ferritic steels. Swelling was greater in specimens that were preimplanted with helium using the tritium trick. The vanadium alloys clearly exhibit lower residual radioactivity after irradiation than the ferrous alloys

  20. Effect of neutron irradiation on vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Braski, D.N.

    1986-01-01

    Neutron-irradiated vanadium alloys were evaluated for their susceptibility to irradiation hardening, helium embrittlement, swelling, and residual radioactivity, and the results were compared with those for the austenitic and ferritic stainless steels. The VANSTAR-7 and V-15Cr-5Ti alloys showed the greatest hardening between 400 and 600/sup 0/C while V-3Ti-1Si and V-20Ti had lower values that were comparable to those of ferritic steels. The V-15Cr-5Ti and VANSTAR-7 alloys were susceptible to helium embrittlement caused by the combination of weakened grain boundaries and irradiation-hardened grain matrices. Specimen fractures were entirely intergranular in the most severe instances of embrittlement. The V-3Ti-1Si and V-20Ti alloys were more resistant to helium embrittlement. Except for VANSTAR-7 irradiated to 40 dpa at 520/sup 0/C, all of the vanadium alloys exhibited low swelling that was similar to the ferritic steels. Swelling was greater in specimens that were preimplanted with helium using the tritium trick. The vanadium alloys clearly exhibit lower residual radioactivity after irradiation than the ferrous alloys.

  1. Vanadium alloys for structural applications in fusion systems: A review of vanadium alloy mechanical and physical properties

    Energy Technology Data Exchange (ETDEWEB)

    Loomis, B.A.; Smith, D.L.

    1991-12-16

    The current knowledge is reviewed on (1) the effects of neutron irradiation on tensile strength and ductility, ductile-brittle transition temperature, creep, fatigue, and swelling of vanadium-base alloys, (2) the compatibility of vanadium-base alloys with liquid lithium, water, and helium environments, and (3) the effects of hydrogen and helium on the physical and mechanical properties of vanadium alloys that are potential candidates for structural materials applications in fusion systems. Also, physical and mechanical properties issues are identified that have not been adequately investigated in order to qualify a vanadium-base alloy for the structural material in experimental fusion devices and/or in fusion reactors.

  2. Vanadium alloys for structural applications in fusion systems: A review of vanadium alloy mechanical and physical properties

    International Nuclear Information System (INIS)

    Loomis, B.A.; Smith, D.L.

    1991-01-01

    The current knowledge is reviewed on (1) the effects of neutron irradiation on tensile strength and ductility, ductile-brittle transition temperature, creep, fatigue, and swelling of vanadium-base alloys, (2) the compatibility of vanadium-base alloys with liquid lithium, water, and helium environments, and (3) the effects of hydrogen and helium on the physical and mechanical properties of vanadium alloys that are potential candidates for structural materials applications in fusion systems. Also, physical and mechanical properties issues are identified that have not been adequately investigated in order to qualify a vanadium-base alloy for the structural material in experimental fusion devices and/or in fusion reactors

  3. Oxygen segregation and its impact on the absorption of hydrogen in vanadium; Einfluss der Sauerstoffsegregation auf die Absorption von Wasserstoff in Vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Paulus, H.; Lammers, M. [Inst. fuer Technologie- und Wissenstransfer, Soest (Germany); Mueller, K.H. [Inst. fuer Technologie- und Wissenstransfer, Soest (Germany)]|[Paderborn Univ. (Gesamthochschule), Soest (Germany). Fachbereich 16 - Elektrische Energietechnik; Kiss, G.; Kemeny, Z. [Technical Univ. Budapest (Hungary)

    1998-12-31

    The impact of the dissolved oxygen on the hydrogen absorption in vanadium was analysed with an UHV apparatus. The vanadium specimen with an oxygen content of 230 ppm was treated by a variety of heat treatments. The depth distributions of the induced concentrations of segregated oxygen in the specimen were analysed by SIMS. It was found that the amount of segregated oxygen increases with rising final temperature and tempering period. In a further experiment, the specimen was exposed after each segregation process to a H{sub 2}-pressure of 2.2 x 10{sup -4} Pa for a period of 1800 sec. The hydrogen amounts absorbed in the specimen were determined by thermal desorption mass spectrometry (TDMS). It was found that segregation of oxygen close to the surface of the specimen likewise hampers the absorption of hydrogen. (orig./CB) [Deutsch] Der Einfluss des im Volumen geloesten Sauerstoffs auf die Wasserstoff-Absorption in Vanadium wurde in einer UHV-Apparatur untersucht. Zunaechst wurde die V-Probe mit einem Sauerstoffgehalt von 230 ppm unterschiedlichen thermischen Behandlungen ausgesetzt. Die sich einstellenden Konzentrationstiefenverteilungen des an der Oberflaeche segregierten Sauerstoffs wurden anschliessend mit SIMS untersucht. Dabei nimmt die Menge des segregierten Sauerstoffs mit der Hoehe der Endtemperatur sowie der Temperzeit zu. In einem weiteren Experiment wurde die Probe nach jeder Segregationsprozedur fuer eine Zeit von 1800 sec einem H{sub 2}-Druck von 2.2 x 10{sup -4} Pa ausgesetzt. Die Mengen des dabei aufgenommenen Wasserstoffs wurden mit Hilfe der thermischen Desorptions-Massenspektrometrie TDMS bestimmt. Dabei zeigt sich, dass auch die Segregation von Sauerstoff im oberflaechennahen Bereich die Wasserstoffaufnahme in Vanadium behindert. (orig.)

  4. X-Ray Absorption Studies of Vanadium-Containing Metal Oxide Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Hohn, Keith, L.

    2006-01-09

    Metal oxide nanocrystals offer significant potential for use as catalysts or catalyst supports due to their high surface areas and unique chemical properties that result from the high number of exposed corners and edges. However, little is known about the catalytic activity of these materials, especially as oxidation catalysts. This research focused on the preparation, characterization and use of vanadium-containing nanocrystals as selective oxidation catalysts. Three vanadium-containing nanocrystals were prepared using a modified sol-gel procedure: V/MgO, V/SiO2, and vanadium phosphate (VPO). These represent active oxidation catalysts for a number of industrially relevant reactions. The catalysts were characterized by x-ray diffraction and Raman, UV-VIS, infrared and x-ray absorption spectroscopies with the goal of determining the primary structural and chemical differences between nanocrystals and microcrystals. The catalytic activity of these catalysts was also studied in oxidative dehydrogenation of butane and methanol oxidation to formaldehyde. V/MgO nanocrystals were investigated for activity in oxidative dehydrogenation of butane and compared to conventional V/MgO catalysts. Characterization of V/MgO catalysts using Raman spectroscopy and x-ray absorption spectroscopy showed that both types of catalysts contained magnesium orthovanadate at vanadium loadings below 15 weight%, but above that loading, magnesium pyrovanadate may have been present. In general, MgO nanocrystals had roughly half the crystal size and double the surface area of the conventional MgO. In oxidative dehydrogenation of butane, nanocrystalline V/MgO gave higher selectivity to butene than conventional V/MgO at the same conversion. This difference was attributed to differences in vanadium domain size resulting from the higher surface areas of the nanocrystalline support, since characterization suggested that similar vanadium phases were present on both types of catalysts. Experiments in

  5. One-step preparation and photocatalytic performance of vanadium doped TiO{sub 2} coatings

    Energy Technology Data Exchange (ETDEWEB)

    Vasilić, R., E-mail: rastko.vasilic@ff.bg.ac.rs [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Stojadinović, S. [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Radić, N. [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia); Stefanov, P. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, Sofia 1113 (Bulgaria); Dohčević-Mitrović, Z. [University of Belgrade, Institute of Physics, Pregrevica 118, 11080 Belgrade (Serbia); Grbić, B. [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia)

    2015-02-01

    In this paper, we have investigated one-step preparation of vanadium doped TiO{sub 2} coatings formed by plasma electrolytic oxidation (PEO) of titanium in electrolyte containing 10 g/L Na{sub 3}PO{sub 4}·12H{sub 2}O + 0.5 g/L NH{sub 4}VO{sub 3}. The morphology, phase structure, and elemental composition of the formed coatings were characterized by atomic force microscopy (AFM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) techniques. Ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS) was employed to evaluate the band gap energy of obtained coatings. Vanadium doped TiO{sub 2} coatings are partly crystallized and mainly composed of anatase phase TiO{sub 2}, with up to about 2 wt% of vanadium present in the surface layer of the oxide. The valence band photoelectron spectra and UV–Vis DRS showed that vanadium doped TiO{sub 2} coatings exhibit notable red shift with respect to the pure TiO{sub 2} coatings. The photocatalytic activity was evaluated by monitoring the degradation of methyl orange under simulated sunlight conditions. Photocatalytic activity of vanadium doped TiO{sub 2} coatings increases with PEO time. Prolonged PEO times result in higher roughness of obtained coatings, thus increasing surface area available for methyl orange degradation. Vanadium doped TiO{sub 2} coatings obtained after 180 s of PEO time exhibit the best photocatalytic activity and about 67% of methyl orange is degraded after 12 h of irradiation under simulated sunlight. - Highlights: • One-step preparation of V-doped TiO{sub 2} coatings in 10 g/L Na{sub 3}PO{sub 4}·12H{sub 2}O + 0.5 g/L NH{sub 4}VO{sub 3}. • Properties of obtained coatings strongly depend on microdischarge characteristics. • Band gap of V-doped TiO{sub 2} coatings is shifted towards red side of the spectrum. • V-doped TiO{sub 2} coatings have better photocatalytic activity than pure TiO{sub 2}. • After 12 h of simulated sunlight irradiation, 67% of

  6. One-step preparation and photocatalytic performance of vanadium doped TiO2 coatings

    International Nuclear Information System (INIS)

    Vasilić, R.; Stojadinović, S.; Radić, N.; Stefanov, P.; Dohčević-Mitrović, Z.; Grbić, B.

    2015-01-01

    In this paper, we have investigated one-step preparation of vanadium doped TiO 2 coatings formed by plasma electrolytic oxidation (PEO) of titanium in electrolyte containing 10 g/L Na 3 PO 4 ·12H 2 O + 0.5 g/L NH 4 VO 3 . The morphology, phase structure, and elemental composition of the formed coatings were characterized by atomic force microscopy (AFM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) techniques. Ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS) was employed to evaluate the band gap energy of obtained coatings. Vanadium doped TiO 2 coatings are partly crystallized and mainly composed of anatase phase TiO 2 , with up to about 2 wt% of vanadium present in the surface layer of the oxide. The valence band photoelectron spectra and UV–Vis DRS showed that vanadium doped TiO 2 coatings exhibit notable red shift with respect to the pure TiO 2 coatings. The photocatalytic activity was evaluated by monitoring the degradation of methyl orange under simulated sunlight conditions. Photocatalytic activity of vanadium doped TiO 2 coatings increases with PEO time. Prolonged PEO times result in higher roughness of obtained coatings, thus increasing surface area available for methyl orange degradation. Vanadium doped TiO 2 coatings obtained after 180 s of PEO time exhibit the best photocatalytic activity and about 67% of methyl orange is degraded after 12 h of irradiation under simulated sunlight. - Highlights: • One-step preparation of V-doped TiO 2 coatings in 10 g/L Na 3 PO 4 ·12H 2 O + 0.5 g/L NH 4 VO 3 . • Properties of obtained coatings strongly depend on microdischarge characteristics. • Band gap of V-doped TiO 2 coatings is shifted towards red side of the spectrum. • V-doped TiO 2 coatings have better photocatalytic activity than pure TiO 2 . • After 12 h of simulated sunlight irradiation, 67% of methyl orange was decomposed

  7. Characteristics of Vanadium Doped And Bamboo Activated Carbon Coated LiFePO4 And Its Performance For Lithium Ion Battery Cathode

    Directory of Open Access Journals (Sweden)

    Nofrijon Sofyan

    2018-04-01

    Full Text Available Vanadium doped and bamboo activated carbon coated lithium iron phosphate (LiFePO4 used for lithium ion battery cathode has been successfully prepared. Lithium iron phosphate was prepared through a wet chemical method followed by a hydrothermal process from the starting materials of LiOH, NH4H2PO4, and FeSO4.7H2O. The dopant variations of 0 wt.%, 3 wt.%, 5 wt.%, and 7 wt.% of vanadium and a fixed 3 wt.% of bamboo activated carbon were carried out via a solid-state reaction process each by using NH4VO3 as a source of vanadium and carbon pyrolyzed from bamboo tree, respectively. The characterization was carried out using X-ray Diffraction (XRD for the phase formed and its crystal structure, Scanning Electron Microscope (SEM for the surface morphology, Electrochemical Impedance Spectroscopy (EIS for the conductivity, and battery analyzer for the performance of lithium ion battery cathode. The XRD results show that the phase formed has an olivine based structure with an orthorhombic space group. Morphology examination revealed that the particle agglomeration decreased with the increasing level of vanadium concentrations. Conductivity test showed that the impedance of solid electrolyte interface decreased with the increase of vanadium concentration indicated by increasing conductivity of 1.25 x 10-5 S/cm, 2.02 x 10-5 S/cm, 4.37 x 10-5 S/cm, and 5.69 x 10-5 S/cm, each for 0 wt.%, 3 wt.%, 5 wt.%, and 7 wt.% vanadium, respectively. Vanadium doping and bamboo activated carbon coating are promising candidate for improving lithium ion battery cathode as the initial charge and discharge capacity at 0.5C for LiFePO4/C at 7 wt.% vanadium is in the range of 8.0 mAh/g.

  8. 77 FR 51825 - Ferrovanadium and Nitrided Vanadium From Russia

    Science.gov (United States)

    2012-08-27

    ... Nitrided Vanadium From Russia Determination On the basis of the record \\1\\ developed in the subject five... order on ferrovanadium and nitrided vanadium from Russia would not be likely to lead to continuation or recurrence of material injury to an industry in the United States within a reasonably foreseeable time. \\1...

  9. Reaction between vanadium trichloride oxide and hydrogen sulfide

    International Nuclear Information System (INIS)

    Yajima, Akimasa; Matsuzaki, Ryoko; Saeki, Yuzo

    1978-01-01

    The details of the reaction between vanadium trichloride oxide and hydrogen sulfide were examined at 20 and 60 0 C. The main products by the reaction were vanadium dichloride oxide, sulfur, and hydrogen chloride. In addition to these products, small amounts of vanadium trichloride, vanadium tetrachloride, disulfur dichloride, and sulfur dioxide were formed. The formations of the above-mentioned reaction products can be explained as follows: The first stage is the reaction between vanadium trichloride oxide and hydrogen sulfide, 2VOCl 3 (l) + H 2 S(g)→2VOCl 2 (s) + S(s) + 2HCl(g). Then the resulting sulfur reacts with the unreacted vanadium trichloride oxide, 2VOCl 3 (l) + 2S(s)→2VOCl 2 (s) + S 2 Cl 2 (l). The resulting disulfur dichloride subsequently reacts with the unreacted vanadium trichloride oxide, 2VOCl 3 (l) + S 2 Cl 2 (l)→2VCl 4 (l) + S(s) + SO 2 (g). The resulting vanadium tetrachloride reacts with the sulfur formed during the reaction, 2VCl 4 (l) + 2S(s)→2VCl 3 (s) + S 2 Cl 2 (l), and also reacts with hydrogen sulfide, 2VCl 4 (l) + H 2 S(g)→2VCl 3 (s) + S(s) + 2HCl(g). (auth.)

  10. Neurotoxic profiles of vanadium when administered at the onset of ...

    African Journals Online (AJOL)

    Pups exposed to vanadium showed reduced upper body strength which was protected by administration of vit E. Routine histology with Haematoxylin and Eosin revealed increased necrotic neurons of the medulla in vanadium exposed rats. Cresyl Violet stain showed depletion of the external granular layer of the ...

  11. Fundamental aspects of alluminothermic reduction of vanadium pentoxide

    International Nuclear Information System (INIS)

    Mourao, M.B.; Capocchi, J.D.T.

    1982-01-01

    The aluminothermic process for the reduction of vanadium pentoxide is considered. Its thermochemistry features are presented, as well as the heat transfer and the rate phenomena concerning such a reaction system. It is pointed out also the effect of the process parameters on the recovery of metallic vanadium. (Author) [pt

  12. A study of defect cluster formation in vanadium by heavy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Sekimura, Naoto; Shirao, Yasuyuki; Morishita, Kazunori [Tokyo Univ. (Japan)

    1996-10-01

    Formation of defect clusters in thin foils of vanadium was investigated by heavy ion irradiation. In the very thin region of the specimens less than 20 nm, vacancy clusters were formed under gold ion irradiation, while very few clusters were detected in the specimens irradiated with 200 and 400 keV self-ions up to 1 x 10{sup 16} ions/m{sup 2}. The density of vacancy clusters were found to be strongly dependent on ion energy. Only above the critical value of kinetic energy transfer density in vanadium, vacancy clusters are considered to be formed in the cascade damage from which interstitials can escape to the specimen surface in the very thin region. (author)

  13. Development of aluminide coatings on vanadium-base alloys in liquid lithium

    International Nuclear Information System (INIS)

    Park, J.H.; Dragel, D.

    1993-01-01

    Aluminide coatings were produced on vanadium and vanadium-base alloys by exposure of the materials to liquid lithium that contained 3/5 at.% dissolved aluminum in sealed V and V-20 wt.% Ti capsules at temperatures between 775 and 880 degrees C. After each test, the capsules were opened and the samples were examined by optical microscopy and scanning electron microscopy (SEM), and analyzed by electron-energy-dispersive spectroscopy (EDS) and X-ray diffraction. Hardness of the coating layers and bulk alloys was determined by microidentation techniques. The nature of the coatings, i.e., surface coverage, thickness, and composition, varied with exposure time and temperature, solute concentration in lithium, and alloy composition. Solute elements that yielded adherent coatings on various substrates can provide a means of developing in-situ electrical insulator coatings by reaction of the reactive layers with dissolved nitrogen in liquid lithium

  14. Vanadium substitution: A simple and economic way to improve UV sensing in ZnO

    Science.gov (United States)

    Srivastava, Tulika; Bajpai, Gaurav; Rathore, Gyanendra; Liu, Shun Wei; Biring, Sajal; Sen, Somaditya

    2018-04-01

    The UV sensing in pure ZnO is due to oxygen adsorption/desorption process from the ZnO surface. Vanadium doping improves the UV sensitivity of ZnO. The enhancement in UV sensitivity in vanadium-substituted ZnO is attributed to trapping and de-trapping of electrons at V4+ and V5+-related defect states. The V4+ state has an extra electron than the V5+ state. A V4+ to V5+ transformation happens with excitation of this electron to the conduction band, while a reverse trapping process liberates a visible light. An analytic study of response phenomenon reveals this trapping and de-trapping process.

  15. Oxidative dehydration of glycerol to acrylic acid over vanadium-impregnated zeolite beta

    Energy Technology Data Exchange (ETDEWEB)

    Pestana, Carolina F.M.; Guerra, Antonio C.O.; Turci, Cassia C. [Universidade Federal do Rio de Janeiro, RJ (Brazil). Inst. de Quimica; Ferreira, Glaucio B. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Quimica; Mota, Claudio J.A., E-mail: cmota@iq.ufrj.br [INCT Energia e Ambiente, Universidade Federal do Rio de Janeiro, RJ (Brazil)

    2013-01-15

    The oxidative dehydration of glycerol to acrylic acid was studied over vanadium-impregnated zeolite Beta. Catalysts were prepared by wet impregnation of ammonium metavanadate over ammonium-exchanged zeolite Beta, followed by air calcination at 823 K. Impregnation reduced the specific surface area, but did not significantly affected the acidity (Bronsted and Lewis) of the zeolites. The catalytic evaluation was carried out in a fixed bed flow reactor using air as the carrier and injecting glycerol by means of a syringe pump. Acrolein was the main product, with acetaldehyde and hydroxy-acetone (acetol) being also formed. Acrylic acid was formed with approximately 25% selectivity at 548 K over the impregnated zeolites. The result can be explained by XPS (X-ray photoelectron spectroscopy) measurements, which indicated a good dispersion of the vanadium inside the pores. (author)

  16. Thermal desorption of toluene from Vanadium-containing catalysts coated onto various carriers

    Directory of Open Access Journals (Sweden)

    Z. Zheksenbaeva

    2012-12-01

    Full Text Available The method temperature-programmed desorption has been studied the state of toluene on the surface-modified vanadium catalysts on different carriers. Among the investigated carriers the most active in the reaction of partial oxidation of toluene is anatase structural titanium dioxide. For the partial oxidation of toluene on modified vanadium-containing catalysts deposited on TiO2 was tested. It was found that on the catalyst 20%V2O5-5%MoO3-2%Sb2O3/TiO2 at a temperature of 673K, volume rate of 15 thousand hours-1 oxidation of toluene is 80% c yield of benzoic acid with a selectivity of  70% of 87.5%.

  17. Oxidative dehydration of glycerol to acrylic acid over vanadium-impregnated zeolite beta

    International Nuclear Information System (INIS)

    Pestana, Carolina F.M.; Guerra, Antonio C.O.; Turci, Cassia C.

    2013-01-01

    The oxidative dehydration of glycerol to acrylic acid was studied over vanadium-impregnated zeolite Beta. Catalysts were prepared by wet impregnation of ammonium metavanadate over ammonium-exchanged zeolite Beta, followed by air calcination at 823 K. Impregnation reduced the specific surface area, but did not significantly affected the acidity (Bronsted and Lewis) of the zeolites. The catalytic evaluation was carried out in a fixed bed flow reactor using air as the carrier and injecting glycerol by means of a syringe pump. Acrolein was the main product, with acetaldehyde and hydroxy-acetone (acetol) being also formed. Acrylic acid was formed with approximately 25% selectivity at 548 K over the impregnated zeolites. The result can be explained by XPS (X-ray photoelectron spectroscopy) measurements, which indicated a good dispersion of the vanadium inside the pores. (author)

  18. Effective Recovery of Vanadium from Oil Refinery Waste into Vanadium-Based Metal-Organic Frameworks.

    Science.gov (United States)

    Zhan, Guowu; Ng, Wei Cheng; Lin, Wenlin Yvonne; Koh, Shin Nuo; Wang, Chi-Hwa

    2018-03-06

    Carbon black waste, an oil refinery waste, contains a high concentration of vanadium(V) leftover from the processing of crude oil. For the sake of environmental sustainability, it is therefore of interest to recover the vanadium as useful products instead of disposing of it. In this work, V was recovered in the form of vanadium-based metal-organic frameworks (V-MOFs) via a novel pathway by using the leaching solution of carbon black waste instead of commercially available vanadium chemicals. Two different types of V-MOFs with high levels of crystallinity and phase purity were fabricated in very high yields (>98%) based on a coordination modulation method. The V-MOFs exhibited well-defined and controlled shapes such as nanofibers (length: > 10 μm) and nanorods (length: ∼270 nm). Furthermore, the V-MOFs showed high catalytic activities for the oxidation of benzyl alcohol to benzaldehyde, indicating the strong potential of the waste-derived V-MOFs in catalysis applications. Overall, our work offers a green synthesis pathway for the preparation of V-MOFs by using heavy metals of industrial waste as the metal source.

  19. Effect of substrate temperature on thermochromic vanadium dioxide thin films sputtered from vanadium target

    Science.gov (United States)

    Madiba, I. G.; Kotsedi, L.; Ngom, B. D.; Khanyile, B. S.; Maaza, M.

    2018-05-01

    Vanadium dioxide films have been known as the most promising thermochromic thin films for smart windows which self-control the solar radiation and heat transfer for energy saving, comfort in houses and automotives. Such an attractive technological application is due to the fact that vanadium dioxide crystals exhibit a fast semiconductor-to-metal phase transition at a transition temperature Tc of about 68 °C, together with sharp optical changes from high transmitive to high reflective coatings in the IR spectral region. The phase transition has been associated with the nature of the microstructure, stoichiometry and stresses related to the oxide. This study reports on the effect of the crystallographic quality controlled by the substrate temperature on the thermochromic properties of vanadium dioxide thin films synthesized by reactive radio frequency inverted cylindrical magnetron sputtering from vanadium target. The reports results are based on X-ray diffraction, Atomic force microscopy, and UV-Visible spectrophotometer. The average crystalline grain size of VO2 increases with the substrate temperature, inducing stress related phenomena within the films.

  20. Theoretical study of the influence of cation vacancies on the catalytic properties of vanadium antimonate

    International Nuclear Information System (INIS)

    Messina, S.; Juan, A.; Larrondo, S.; Irigoyen, B.; Amadeo, N.

    2008-01-01

    We have theoretically studied the influence of antimony and vanadium cation vacancies in the electronic structure and reactivity of vanadium antimonate, using molecular orbital methods. From the analysis of the electronic properties of the VSbO 4 crystal structure, we can infer that both antimony and vanadium vacancies increase the oxidation state of closer V cations. This would indicate that, in the rutile-type VSbO 4 phase the Sb and V cations defects stabilize the V in a higher oxidation state (V 4+ ). Calculations of the adsorption energy for different toluene adsorption geometries on the VSbO 4 (1 1 0) surface have also been performed. The oxidation state of Sb, V and O atoms and the overlap population of metal-oxygen bonds have been evaluated. Our results indicate that the cation defects influence in the toluene adsorption reactions is slight. We have computed different alternatives for the reoxidation of the VSbO 4 (1 1 0) surface active sites which were reduced during the oxygenated products formation. These calculations indicate that the V cations in higher oxidation state (V 4+ ) are the species, which preferentially incorporate lattice oxygen to the reduced Sb cations. Thus, the cation defects would stabilize the V 4+ species in the VSbO 4 structure, determining its ability to provide lattice oxygen as a reactant

  1. Na-Ion Intercalation and Charge Storage Mechanism in 2D Vanadium Carbide

    Energy Technology Data Exchange (ETDEWEB)

    Bak, Seong-Min [Chemistry Division, Brookhaven National Laboratory, Upton NY 11973 USA; Qiao, Ruimin [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley CA 94720 USA; Yang, Wanli [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley CA 94720 USA; Lee, Sungsik [X-Ray Science Division, Argonne National Laboratory, Argonne IL 60439 USA; Yu, Xiqian [Institute of Physics, Chinese Academy of Science, Beijing 100190 China; Anasori, Babak [Department of Material Science and Engineering, A.J. Drexel Nanomaterials Institute, Drexel University, Philadelphia PA 19104 USA; Lee, Hungsui [Chemistry Division, Brookhaven National Laboratory, Upton NY 11973 USA; Gogotsi, Yury [Department of Material Science and Engineering, A.J. Drexel Nanomaterials Institute, Drexel University, Philadelphia PA 19104 USA; Yang, Xiao-Qing [Chemistry Division, Brookhaven National Laboratory, Upton NY 11973 USA

    2017-07-14

    Two-dimensional vanadium carbide MXene containing surface functional groups (denoted as V2CTx, where Tx are surface functional groups) was synthesized and studied as anode material for Na-ion batteries. V2CTx anode exhibits reversible charge storage with good cycling stability and high rate capability through electrochemical test. The charge storage mechanism of V2CTx material during Na+ intercalation/deintercalation and the redox reaction of vanadium were studied using a combination of synchrotron based X-ray diffraction (XRD), hard X-ray absorption near edge spectroscopy (XANES) and soft X-ray absorption spectroscopy (sXAS). Experimental evidence of a major contribution of redox reaction of vanadium to the charge storage and the reversible capacity of V2CTx during sodiation/desodiation process have been provided through V K-edge XANES and V L2,3-edge sXAS results. A correlation between the CO32- content and Na+ intercalation/deintercalation states in the V2CTx electrode observed from C and O K-edge in sXAS results imply that some additional charge storage reactions may take place between the Na+-intercalated V2CTx and the carbonate based non-aqueous electrolyte. The results of this study will provide valuable information for the further studies on V2CTx as anode material for Na-ion batteries and capacitors.

  2. Chemistry related to the procurement of vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Smith, H.M.; Chung H.M.; Tsai, H.C. [Argonne National Lab., IL (United States)

    1997-08-01

    Evaluation of trace element concentrations in vanadium alloys is important to characterize the low-activation characteristics and possible effects of trace elements on the properties. Detailed chemical analysis of several vanadium and vanadium alloy heats procured for the Argonne vanadium alloy development program were analyzed by Johnson-Matthey (UK) as part of a joint activity to evaluate trace element effects on the performance characteristics. These heats were produced by normal production practices for high grade vanadium. The analyses include approximately 60 elements analyzed in most cases by glow-discharge mass spectrometry. Values for molybdenum and niobium, which are critical for low-activation alloys, ranged from 0.4 to 60 wppm for the nine heats.

  3. Recent progress on gas tungsten arc welding of vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    King, J.F.; Grossbeck, M.L.; Goodwin, G.M.; Alexander, D.J. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    This is a progress report on a continuing research project to acquire a fundamental understanding of the metallurgical processes in the welding of vanadium alloys. It also has the goal of developing techniques for welding structural vanadium alloys. The alloy V-4Cr-4Ti is used as a representative alloy of the group; it is also the prime candidate vanadium alloy for the U.S. Fusion Program at the present time. However, other alloys of this class were used in the research as necessary. The present work focuses on recent findings of hydrogen embrittlement found in vanadium alloy welds. It was concluded that the atmosphere in the inert gas glove box was insufficient for welding 6mm thick vanadium alloy plates.

  4. Vanadium Extraction from Shale via Sulfuric Acid Baking and Leaching

    Science.gov (United States)

    Shi, Qihua; Zhang, Yimin; Liu, Tao; Huang, Jing

    2018-01-01

    Fluorides are widely used to improve vanadium extraction from shale in China. Sulfuric acid baking-leaching (SABL) was investigated as a means of recovering vanadium which does not require the use of fluorides and avoids the productions of harmful fluoride-containing wastewater. Various effective factors were systematically studied and the experimental results showed that 90.1% vanadium could be leached from the shale. On the basis of phase transformations and structural changes after baking the shale, a mechanism of vanadium extraction from shale via SABL was proposed. The mechanism can be described as: (1) sulfuric acid diffusion into particles; (2) the formation of concentrated sulfuric acid media in the particles after water evaporation; (3) hydroxyl groups in the muscovite were removed and transient state [SO4 2-] was generated; and (4) the metals in the muscovite were sulfated by active [SO4 2-] and the vanadium was released. Thermodynamics modeling confirmed this mechanism.

  5. Chemistry related to the procurement of vanadium alloys

    International Nuclear Information System (INIS)

    Smith, H.M.; Chung H.M.; Tsai, H.C.

    1997-01-01

    Evaluation of trace element concentrations in vanadium alloys is important to characterize the low-activation characteristics and possible effects of trace elements on the properties. Detailed chemical analysis of several vanadium and vanadium alloy heats procured for the Argonne vanadium alloy development program were analyzed by Johnson-Matthey (UK) as part of a joint activity to evaluate trace element effects on the performance characteristics. These heats were produced by normal production practices for high grade vanadium. The analyses include approximately 60 elements analyzed in most cases by glow-discharge mass spectrometry. Values for molybdenum and niobium, which are critical for low-activation alloys, ranged from 0.4 to 60 wppm for the nine heats

  6. Exploring electrolyte preference of vanadium nitride supercapacitor electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bo; Chen, Zhaohui; Lu, Gang [Department of Electrical Engineering and Automation, Luoyang Institute of Science and Technology, Luoyang 471023 (China); Wang, Tianhu [School of Electrical Information and Engineering, Jiangsu University of Technology, Changzhou 213001 (China); Ge, Yunwang, E-mail: ywgelit@126.com [Department of Electrical Engineering and Automation, Luoyang Institute of Science and Technology, Luoyang 471023 (China)

    2016-04-15

    Highlights: • Hierarchical VN nanostructures were prepared on graphite foam. • Electrolyte preference of VN supercapacitor electrodes was explored. • VN showed better capacitive property in organic and alkaline electrolytes than LiCl. - Abstract: Vanadium nitride hierarchical nanostructures were prepared through an ammonia annealing procedure utilizing vanadium pentoxide nanostructures grown on graphite foam. The electrochemical properties of hierarchical vanadium nitride was tested in aqueous and organic electrolytes. As a result, the vanadium nitride showed better capacitive energy storage property in organic and alkaline electrolytes. This work provides insight into the charge storage process of vanadium nitride and our findings can shed light on other transition metal nitride-based electrochemical energy storage systems.

  7. Raman and XPS characterization of vanadium oxide thin films with temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ureña-Begara, Ferran, E-mail: ferran.urena@uclouvain.be [Université catholique de Louvain, Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Louvain-la-Neuve (Belgium); Crunteanu, Aurelian [XLIM Research Institute, UMR 7252, CNRS/Université de Limoges, Limoges (France); Raskin, Jean-Pierre [Université catholique de Louvain, Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Louvain-la-Neuve (Belgium)

    2017-05-01

    Highlights: • Comprehensive study of the oxidation of VO{sub 2} thin films from R.T. up to 550 °C. • Phase changes and mixed-valence vanadium oxides formed during the oxidation process. • Reported Raman and XPS signatures for each vanadium oxide. • Monitoring of the current and resistance evolution at the surface of the films. • Oxidation model describing the evolution of the vanadium oxides and phase changes. - Abstract: The oxidation mechanisms and the numerous phase transitions undergone by VO{sub 2} thin films deposited on SiO{sub 2}/Si and Al{sub 2}O{sub 3} substrates when heated from room temperature (R.T.) up to 550 °C in air are investigated by Raman and X-ray photoelectron spectroscopy. The results show that the films undergo several intermediate phase transitions between the initial VO{sub 2} monoclinic phase at R.T. and the final V{sub 2}O{sub 5} phase at 550 °C. The information about these intermediate phase transitions is scarce and their identification is important since they are often found during the synthesis of vanadium dioxide films. Significant changes in the film conductivity have also been observed to occur associated to the phase transitions. In this work, current and resistance measurements performed on the surface of the films are implemented in parallel with the Raman measurements to correlate the different phases with the conductivity of the films. A model to explain the oxidation mechanisms and phenomena occurring during the oxidation of the films is proposed. Peak frequencies, full-width half-maxima, binding energies and oxidation states from the Raman and X-ray photoelectron spectroscopy experiments are reported and analyzed for all the phases encountered in VO{sub 2} films prepared on SiO{sub 2}/Si and Al{sub 2}O{sub 3} substrates.

  8. Thermochemical investigation of lithium-vanadium bronzes

    International Nuclear Information System (INIS)

    Filippova, S.E.; Kesler, Ya.A.; Tret'yakov, Yu.D.; Gordeev, I.V.

    1979-01-01

    A thermochemical investigation was carried out of lithium-vanadium bronzes. The enthalpies of solution and the standard enthalpies of formation of the bronzes β-Lisub(x)Vsub(2)Osub(5) were determined. Investigated was the dependence of the enthalpy of mixing bronzes on the composition; a linear character of the dependence evidences of negligibly small, as compared to the experimental error, energy variations of the matrix V 2 O 5 on introduction of lithium. The variation was calculated of the partial molar enthalpy of lithium in the formation of β-Lisub(x)Vsub(2)Osub(5)

  9. Color and vanadium valency in V-doped ZrO2

    International Nuclear Information System (INIS)

    Ren, Feng; Ishida, Shingo; Takeuchi, Nobuyuki

    1993-01-01

    The distribution and chemical states of vanadium in V-doped ZrO 2 were studied to clarify the origin of the color of vanadium-zirconium yellow pigment in comparison with vanadium-tin yellow pigment. ESCA data and measurements of lattice constants of V-doped ZrO 2 revealed that vanadium was dissolved mainly as V 4+ substituting for Zr in ZrO 2 lattice, and its solubility limit was 0.5 wt% as V 2 O 5 . It was found that the yellow color of vanadium-zirconium yellow was produced predominantly by the dissolved vanadium and that the contribution of vanadium oxide on ZrO 2 grains to the yellow color was about 1.30 of that of the dissolved vanadium when compared on the basis of equimolar quantity of vanadium. Most of the undissolved vanadium oxide was in an amorphous or a poorly crystallized state

  10. Mesoporous tungsten oxynitride as electrocatalyst for promoting redox reactions of vanadium redox couple and performance of vanadium redox flow battery

    Science.gov (United States)

    Lee, Wonmi; Jo, Changshin; Youk, Sol; Shin, Hun Yong; Lee, Jinwoo; Chung, Yongjin; Kwon, Yongchai

    2018-01-01

    For enhancing the performance of vanadium redox flow battery (VRFB), a sluggish reaction rate issue of V2+/V3+ redox couple evaluated as the rate determining reaction should be addressed. For doing that, mesoporous tungsten oxide (m-WO3) and oxyniride (m-WON) structures are proposed as the novel catalysts, while m-WON is gained by NH3 heat treatment of m-WO3. Their specific surface area, crystal structure, surface morphology and component analysis are measured using BET, XRD, TEM and XPS, while their catalytic activity for V2+/V3+ redox reaction is electrochemically examined. As a result, the m-WON shows higher peak current, smaller peak potential difference, higher electron transfer rate constant and lower charge transfer resistance than other catalysts, like the m-WO3, WO3 nanoparticle and mesoporous carbon, proving that it is superior catalyst. Regarding the charge-discharge curve tests, the VRFB single cell employing the m-WON demonstrates high voltage and energy efficiencies, high specific capacity and low capacity loss rate. The excellent results of m-WON are due to the reasons like (i) reduced energy band gap, (ii) reaction familiar surface functional groups and (ii) greater electronegativity.

  11. Acute toxicity of vanadium to the threespine stickleback, Gasterosteus aculeatus

    Energy Technology Data Exchange (ETDEWEB)

    Gravenmier, J.J.; Johnston, D.W.; Arnold, W.R. [Blasland Bouck & Lee Inc, Petaluma, CA (US)

    2005-02-15

    Vanadium is widely distributed, occurring in many types of minerals, coal, and petroleum. Anthropogenic sources of vanadium originate from the production, processing, and wastes of these materials. The aquatic toxicity of vanadium to fish species is not well characterized. This study focused on the three-spined stickleback, Gasterosteus aculeatus, a small and widely distributed euryhaline species of fish. The three-spined stickleback is used as an effluent-monitoring species in both Canada and the United States. Five 96-h static renewal acute toxicity tests were performed in moderately hard water with adult fish. The geometric mean and range of the five 96-h LC{sup 50}s based on measured concentrations of total vanadium in the test solution were 3.17 and 2.35-4.07 mg V/L, respectively. A conservative estimation of a safe concentration of vanadium that would not affect survival of adult three-spined sticklebacks over a 96-h exposure period in moderately hard water is approximately 0.30 mg V/L. A comparison with other fish species previously tested suggests that the three-spined stickleback is intermediate in sensitivity to vanadium. Information reported from this study may be useful in effluent toxicity identification evaluations and ecological risk assessments related to vanadium.

  12. Vanadium extraction from slimes by the lime-bicarbonate method

    International Nuclear Information System (INIS)

    Lishchenko, T.V.; Vdovina, L.V.; Slobodchikova, R.I.

    1978-01-01

    Some main parameters of the lime-bicarbonate method of extracting vanadium from residues obtained in washing waters of mazut boilers on thermal stations have been determined. To study the process of vanadium extraction during caking of the residues with lime and subsequent leaching of water-soluble vanadium, a ''Minsk-22'' computer has been used for computation. Analysis of the equation derived has shown that a change in temperature of vanadium leaching, density of pulp, and a kind of heating of the charge affect the process only slightly. It has also been shown that the calcination temperature is expedient to be kept above 850 deg C and consumption temperature is expedient to be kept above 85O deg C and consumption of lime must not exceed 20% of the residues weight. Bicarbonate consumption exerts a decisive influence on completeness of vanadium extraction and must be increased up to >35%; duration of leaching should be raised up to 30-45 minutes. With increasing calcination temperature the duration of leaching decreases. When temperature and duration of calcination increase, the formation of water-soluble vanadium intensifies. With the aid of optimization program seven variants have been chosen, which ensure vanadium extraction into solution by 95-100%

  13. Hydrometallurgic treatment of a mineral containing uranium, vanadium and phosphorus

    International Nuclear Information System (INIS)

    Echenique, Patricia; Fruchtenicht, Fernando; Gil, Daniel; Vigo, Daniel; Bouza, Angel; Vert, Gabriela; Becquart, Elena

    1987-01-01

    A preliminary study of a mineral has been made towards the hydrometallurgy separation of uranium, vanadium and phosphorus. After the ore dressing, work on sulfuric acid with oxidation leaching has been made, to get the uranium, vanadium and phosphorus in solution. For the separation and purification of these elements, two alternative solvent extraction methods have been tested. One of them has been the extraction of uranium and vanadium and a selective stripping of both elements. The second one has been the selective extraction of uranium and vanadium at different aqueous solutions pH. In both methods, the same reagent has been used: di(2-ethylhexyl) phosphoric acid, kerosene as diluent with two different synergistic agents: TOPO (tri-n-octyl phosphine oxide) and TBP (tri-n-butyl phosphate). Batch studies have been made to determine the equilibrium isotherms for uranium and vanadium. A continuous countercurrent simulation method has been used to get the best phase ratio and to test different stripping agents. For the first method, an important loss of uranium and vanadium at the feed solution conditioning for the extraction step has been observed. For the second method, a good recovery of uranium has been reached, but there has been losses of vanadium in pH adjustment. Nevertheless, among these processes, the last seems to work better in this mineral hydrometallurgy. (Author) [es

  14. Analysis and measurement of residual stress distribution of vanadium/ceramics joints for fusion reactor applications

    International Nuclear Information System (INIS)

    Nemoto, Y.; Ueda, K.

    1998-01-01

    Vanadium alloys are considered as candidate structural materials for fusion reactor system. When vanadium alloys are used in fusion reactor system, joining with ceramics for insulating is one of material issues to be solved to make component of fusion reactor. In the application of ceramics/metal jointing and coating, residual stress caused by difference of thermal expansion rate between ceramics and metals is an important factor in obtaining good bonding strength and soundness of coating. In this work, residual stress distribution in direct diffusion bonded vanadium/alumina joint (jointing temperature: 1400 C) was measured by small area X-ray diffraction method. And the comparison of finite element method (FEM) analysis and actual stress distribution was carried out. Tensile stress concentration at the edge of the boundary of the joint in alumina was observed. The residual stress concentration may cause cracks in alumina, or failure of bonding. Actually, cracks in alumina caused by thermal stress after bonding at 1500 C was observed. The stress concentration of the joint must be reduced to obtain good bonded joint. Lower bonding temperature or to devise the shape of the outer surface of the joint will reduce the stress concentration. (orig.)

  15. A new oxidimetric reagent: potassium dichromate in a strong phosphoric acid medium-VI Potentiometric titration of vanadium(III) alone and in mixture with vanadium(IV).

    Science.gov (United States)

    Rao, G G; Rao, P K

    1966-09-01

    Vanadium(III) can be titrated at room temperature with potassium dichromate in an 8-12M phosphoric acid medium. Two potential breaks are observed in 12M phosphoric add with 0.2N potassium dichromate, the first corresponding to the oxidation of vanadium(III) to vanadium(IV) and the second to the oxidation of vanadium(IV) to vanadium(V). In titrations with 0.05N dichromate only the first break in potential is clearly observed. The method has been extended to the titration of mixtures of vanadium(III) and vanadium(IV). Conditions have also been found for the visual titration of vanadium(III) using ferroln or barium diphenylamine sulphonate as indicator.

  16. Vanadium-base alloys for fusion reactor applications

    International Nuclear Information System (INIS)

    Smith, D.L.; Loomis, B.A.; Diercks, D.R.

    1984-10-01

    Vanadium-base alloys offer potentially significant advantages over other candidate alloys as a structural material for fusion reactor first wall/blanket applications. Although the data base is more limited than that for the other leading candidate structural materials, viz., austenitic and ferritic steels, vanadium-base alloys exhibit several properties that make them particularly attractive for the fusion reactor environment. This paper presents a review of the structural material requirements, a summary of the materials data base for selected vanadium-base alloys, and a comparison of projected performance characteristics compared to other candidate alloys. Also, critical research and development (R and D) needs are defined

  17. Vanadium-base alloys for fusion reactor applications

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D.L.; Loomis, B.A.; Diercks, D.R.

    1984-10-01

    Vanadium-base alloys offer potentially significant advantages over other candidate alloys as a structural material for fusion reactor first wall/blanket applications. Although the data base is more limited than that for the other leading candidate structural materials, viz., austenitic and ferritic steels, vanadium-base alloys exhibit several properties that make them particularly attractive for the fusion reactor environment. This paper presents a review of the structural material requirements, a summary of the materials data base for selected vanadium-base alloys, and a comparison of projected performance characteristics compared to other candidate alloys. Also, critical research and development (R and D) needs are defined.

  18. TiAl doping by vanadium: ab initio study

    International Nuclear Information System (INIS)

    Smirnova, E.A.; Isaev, Eh.I.; Vekilov, Yu.Kh.

    2004-01-01

    Tetragonality degree in TiAl and vanadium doping effect on it were studied using the methods of calculation based on approximation of coherent potential and ab initio pseudopotentials. It is shown that vanadium substitution for Ti sublattice atoms entails increase in tetragonality degree but with substitution of the atoms in aluminium sublattice the tetragonality of the TiAl:V alloy decreases and at the content of vanadium about 8 at. % the lattice becomes actually cubical. In its turn, it may result in increase in TiAl ductility, the alloy being brittle at low temperatures [ru

  19. Hydrogen release from vanadium alloy V-4Cr-4Ti

    International Nuclear Information System (INIS)

    Klepikov, A.Kh; Kulsartov, T.V.; Chikhray, E.V.; Romanenko, O.G.; Tazhibaeva, I.L.; Shestakov, V.P.

    1999-01-01

    The experiments on hydrogen loading of vanadium alloy with the following thermodesorption spectroscopy (TDS) measurements were carried out with the sample of the V-4Cr-4Ti vanadium alloy (Russia production). Hydrogen solubility was calculated from experimental TDS curves, obtained after equilibrium loading of the sample at the temperatures 673, 773, 873, 973, and 1073 K. The range of loading pressures was 10-100 Pa. The experiments carried out had an objective to determine the regimes (loading time, temperatures and pressures) for the experiment on in-pile loading of the vanadium alloy. (author)

  20. Spectrophotometric determination of vanadium in environmental and biological samples

    International Nuclear Information System (INIS)

    Rekha, D.; Krishnapriya, B.; Subrahmanyam, P.; Reddyprasad, P.; Dilip Kumar, J.; Chiranjeevi, P.

    2007-01-01

    The method is based on oxidation of p-nitro aniline by vanadium (V) followed by coupling reaction with N-(1-naphthalene-1-y1)ethane-1, 2-diaminedihydrochloride (NEDA) in basic medium of pH 8 to give purple colored derivative. The derivative having an λ max 525nm is stable for 10 days. Beer's law is obeyed for vanadium (V) in the concentration range of 0.03-4.5 μg ml -1 . The proposed method was successfully applied to the analysis of vanadium in environmental and biological samples. (author)

  1. Vanadium and titanium determination by resorcinalhydrazide of salicylic acid

    Energy Technology Data Exchange (ETDEWEB)

    Karpova, O I; Pilipenko, A T; Lukachina, V V [AN Ukrainskoj SSR, Kiev. Inst. Kolloidnoj Khimii i Khimii Vody

    1979-02-01

    The complexing of titanium and vanadium with resorcinalhydrazyl of salicylic acid (RHSA) in water-organic media is studied. Titanium (4) forms a complex at pH 0.8-1.8, vanadium - at pH 2.5-5.6, and at pH 7.6-9.8. The complexes are well extracted by polar and nonpolar solvents from acid solutions. The techniques are developed for the determination of titanium and vanadium by the RHSA agent in nickel alloys.

  2. Vanadium bioavailability and toxicity to soil microorganisms and plants

    OpenAIRE

    Larsson, Maja A; Baken, Stijn; Gustafsson, Jon Petter; Hadialhejazi, Golshid; Smolders, Erik

    2013-01-01

    Vanadium, V, is a redox-sensitive metal that in solution, under aerobic conditions, prevails as the oxyanion vanadate(V). There is little known regarding vanadium toxicity to soil biota, and the present study was set up to determine the toxicity of added vanadate to soil organisms and to investigate the relationship between toxicity and vanadium sorption in soils. Five soils with contrasting properties were spiked with 7 different doses (3.2-3200mgVkg(-1)) of dissolved vanadate, and toxicity ...

  3. Preliminary studies of vanadium-base alloys intended for use in fabrication of cans for fast reactors; Etudes preliminaires sur les alliages a base de vanadium envisages pour la fabrication de gaines de reacteurs rapides

    Energy Technology Data Exchange (ETDEWEB)

    Conte, M [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-03-15

    Preliminary research has been carried out on a series of vanadium-based alloys: V, 0.5 per cent Si; V, 5 per cent Ca; V, 5 per cent Mo; V, 5 per cent Nb; V, 2 per cent Zr; V, 20 per cent Ti; V, 10 per cent Al; V, 10 per cent Sn and v, 10 per cent Ti liable to be used as canning material in fast reactors. The transformation by forging at about 1000 deg. C and rolling between 200 deg. C and room temperature is satisfactory for all types of alloys except V with 10 per cent Sn and V with 10 per cent Al. The mechanical properties deduced from tensile strength tests carried out on alloy samples annealed 1 hour at 1050 deg. C in a vacuum show that, generally speaking, the addition elements lead to an improvement in these properties as compared to those of pure vanadium. After undergoing corrosion tests in a liquid sodium loop purified by a cold trap, the alloys become brittle at room temperature. Only the vanadium containing 20 per cent Ti keeps its plastic properties. These alloys are covered by a layer of vanadium carbide VC. After undergoing treatment in a liquid sodium loop purified by a hot trap, all the alloys keep their good mechanical characteristics. The surface layer with which they are covered is composed of two vanadium carbides VC and {sub {gamma}}VC, and a vanadium sub-oxide VO{sub 0.9}. (author) [French] Des etudes preliminaires ont ete faites sur une serie d'alliages a base de vanadium: V-0,5 pour cent Si, V-5 pour cent Ca, V-5 pour cent Mo, V-5 pour cent Nb, V-2 pour cent Zr, V-20 pour cent Ti, V-10 pour cent Al, V-10 pour cent Sn et V-10 pour cent Ti susceptibles d'etre utilises comme materiau de gainage pour les reacteurs rapides. La transformation par forgeage a 1000 deg. C environ et laminage entre 200 deg. C et la temperature ambiante est satisfaisante pour toutes les nuances d'alliage sauf le V-10 pour cent Sn et le V-10 pour cent Al. Les proprietes mecaniques deduites des essais de traction realises sur des eprouvettes d'alliages recuits 1 heure a

  4. Bioleaching of vanadium from barren stone coal and its effect on the transition of vanadium speciation and mineral phase

    Science.gov (United States)

    Wang, Xin; Lin, Hai; Dong, Ying-bo; Li, Gan-yu

    2018-03-01

    This study determined the optimal conditions required to obtain maximum vanadium extraction and examined the transition of mineral phases and vanadium speciation during the bioleaching process. Parameters including the initial pH value, initial Fe2+ concentration, solid load, and inoculum quantity were examined. The results revealed that 48.92wt% of the vanadium was extracted through bioleaching under optimal conditions. Comparatively, the chemical leaching yield (H2SO4, pH 2.0) showed a slower and milder increase in vanadium yield. The vanadium bioleaching yield was 35.11wt% greater than the chemical leaching yield. The Community Bureau of Reference (BCR) sequential extraction results revealed that 88.62wt% of vanadium existed in the residual fraction. The bacteria substantially changed the distribution of the vanadium speciation during the leaching process, and the residual fraction decreased to 48.44wt%. The X-ray diffraction (XRD) and Fourier transform infrared (FTIR) results provided evidence that the crystal lattice structure of muscovite was destroyed by the bacteria.

  5. Leaching of vanadium from waste V2O5-WO3/TiO2 catalyst catalyzed by functional microorganisms.

    Science.gov (United States)

    Wang, Shuhua; Xie, Yaling; Yan, Weifu; Wu, Xuee; Wang, Chin-Tsan; Zhao, Feng

    2018-05-22

    Solid wastes are currently produced in large amounts. Although bioleaching of metals from solid wastes is an economical and sustainable technology, it has seldom been used to recycle metals from abandoned catalyst. In this study, the bioleaching of vanadium from V 2 O 5 -WO 3 /TiO 2 catalyst were comprehensively investigated through five methods: Oligotrophic way, Eutrophic way, S-mediated way, Fe-mediated way and Mixed way of S-mediated and Fe-mediated. The observed vanadium bioleaching effectiveness of the assayed methods was follows: S-mediated > Mixed > Oligotrophic > Eutrophic > Fe-mediated, which yielded the maximum bioleaching efficiencies of approximately 90%, 35%, 33%, 20% and 7%, respectively. The microbial community analysis suggested that the predominant genera Acidithiobacillus and Sulfobacillus from the S-mediated bioleaching way effectively catalyzed the vanadium leaching, which could have occurred through the indirect mechanism from the microbial oxidation of S 0 . In addition, the direct mechanism, involving direct electron transfer between the catalyst and the microorganisms that attached to the catalyst surface, should also help the vanadium to be leached more effectively. Therefore, this work provides guidance for future research and practical application on the treatment of waste V 2 O 5 -WO 3 /TiO 2 catalyst. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Geochemistry of vanadium in an epigenetic, sandstone-hosted vanadium- uranium deposit, Henry Basin, Utah

    Science.gov (United States)

    Wanty, R.B.; Goldhaber, M.B.; Northrop, H.R.

    1990-01-01

    The epigenetic Tony M vanadium-uranium orebody in south-central Utah is hosted in fluvial sandstones of the Morrison Formation (Upper Jurassic). Measurements of the relative amounts of V+3 and V +4 in ore minerals show that V+3 is more abundant. Thermodynamic calculations show that vanadium was more likely transported to the site of mineralization as V+4. The ore formed as V+4 was reduced by hydrogen sulfide, followed by hydrolysis and precipitation of V+3 in oxide minerals or chlorite. Uranium was transported as uranyl ion (U+6), or some complex thereof, and reduced by hydrogen sulfide, forming coffinite. Detrital organic matter in the rocks served as the carbon source for sulfate-reducing bacteria. Vanadium most likely was derived from the dissolution of iron-titanium oxides. Uranium probably was derived from the overlying Brushy Basin Member of the Morrison Formation. Previous studies have shown that the ore formed at the density-stratified interface between a basinal brine and dilute meteoric water. The mineralization processes described above occurred within the mixing zone between these two fluids. -from Authors

  7. Sputtering of vanadium and niobium under 14.1 MeV neutron impact

    International Nuclear Information System (INIS)

    Kaminsky, M.; Das, S.K.

    1976-01-01

    The recent studies of particle emission from cold-rolled and annealed niobium under 14.1-MeV neutron impact were extended to a heavily etched, polycrystalline niobium surface and to cold worked vanadium surfaces with different degrees of microstructure. The type and amount of material released and deposited on collector surfaces facing the irradiated targets were determined by three analytical techniques. Two types of deposits were found for certain types of surfaces--one in the form of chunks; the other as a fractional atom layer covering the surface. The chunks vary significantly in size. The small number of chunks observed suggests that the ejection of chunks is a relatively rare event in comparison to the total number of primary knock-on events produced by 14-MeV neutrons in near surface regions. Estimates of the total sputtering yield based on the chunk deposits and on the fractional atom layer deposit will be given

  8. Determination of vanadium (4) and (5) in the presence of both

    International Nuclear Information System (INIS)

    Malyuta, V.F.; Solomatin, V.T.; Berezhnoj, A.I.

    1983-01-01

    A study was made on the possibility of vanadium (4) and (5) determination in the presence of both by titration with ferrocene in aqueous solutions. 5-6 M H 2 SO 4 is the optimal medium for vanadium (5) titration. Vanadium (4) is titrated in the mixture of 2-2.5 M H 2 SO 4 and 8-10 M H 3 PO 4 . The method for vanadium (4) and (5) determination in vanadium catalysts was developed. Vanadium (5) is titrated amperometrically or potentiometrically by propanol solution of ferrocence in H 2 SO 4 . Concentrated H 3 PO 4 is added and the summary vanadium (4) is titrated. The relative standard deviations for 0.04-2% vanadium (4) content and 0.3-4% vanadium (5) content equal 0.06-0.03 and 0.05-0.02, respectively

  9. Complexing of vanadium(3) with chromotropic acid derivatives

    International Nuclear Information System (INIS)

    Babenko, N.L.; Busev, A.I.; Sukhorukova, N.V.; Frolova, O.S.

    1976-01-01

    A spectrophotometric study has been made of the complex formation of vanadium (3) with arsenazo(1), arsenazo(3) and some monosubstituted derivatives of chromotropic acid and sulphanylamides. In acid medium vanadium (3) reacts with each of these reagents to produce a 1:1 complex. Optimum conditions of the complex formation was found. The effect of H + on the complex formation of vanadium (3) with chromotropic acid derivatives was established. It was found by the graphical method that the formation of the complex is accompanied by the elimination of one proton. Patterns were found of the influence of the nature of substituents in the organic compound on the ionization constants of acid groups and stability of complexes. Molar extinction coefficients, equilibrium constants of the formation reactions and instability constants for the complexes were calculated. The structure of complexes was suggested. Similar behaviour of all the reagents was established in the complex formation with vanadium (3)

  10. Compatibility of niobium, titanium, and vanadium metals with LMFBR cladding

    International Nuclear Information System (INIS)

    Wilson, C.N.

    1975-10-01

    A series of laboratory capsule annealing experiments were conducted to assess the compatibility of niobium, vanadium, and titanium with 316 stainless steel cladding in the temperature range of 700 to 800 0 C. Niobium, vanadium, and titanium are cantidate oxygen absorber materials for control of oxygen chemistry in LMFBR fuel pins. Capsule examination indicated good compatibility between niobium and 316 stainless steel at 800 0 C. Potential compatibility problems between cladding and vanadium or titanium were indicated at 800 0 C under reducing conditions. In the presence of Pu/sub 0.25/U/sub 0.75/O/sub 1.98/ fuel (Δanti G 02 congruent to -160 kcal/mole) no reaction was observed between vanadium or titanium and cladding at 800 0 C

  11. TEM investigation of ductile iron alloyed with vanadium.

    Science.gov (United States)

    Dymek, S; Blicharski, M; Morgiel, J; Fraś, E

    2010-03-01

    This article presents results of the processing and microstructure evolution of ductile cast iron, modified by an addition of vanadium. The ductile iron was austenitized closed to the solidus (1095 degrees C) for 100 h, cooled down to 640 degrees C and held on at this temperature for 16 h. The heat treatment led to the dissolution of primary vanadium-rich carbides and their subsequent re-precipitation in a more dispersed form. The result of mechanical tests indicated that addition of vanadium and an appropriate heat treatment makes age hardening of ductile iron feasible. The precipitation processes as well as the effect of Si content on the alloy microstructure were examined by scanning and transmission electron microscopy. It was shown that adjacent to uniformly spread out vanadium-rich carbides with an average size of 50 nm, a dispersoid composed of extremely small approximately 1 nm precipitates was also revealed.

  12. Synthesis and infrared spectra of Vanadium (III) prussian blue complexes

    International Nuclear Information System (INIS)

    Toma, H.E.; Lellis, F.T.P.

    1987-01-01

    The synthesis and characterization of a series of polymeric pigments containing vanadium (III) and hexacryano or substituted pentacyanoferrate (II) complexes are studied. The role of the intervalence transfer interactions in the complexes is discussed. (M.J.C.) [pt

  13. Particle fracture and plastic deformation in vanadium pentoxide

    Indian Academy of Sciences (India)

    Particle fracture and plastic deformation in vanadium pentoxide powders induced by high energy vibrational ball-mill ... Keywords. X-ray diffraction; ball-milling; plastic deformation; microstrain. ... Bulletin of Materials Science | News.

  14. Application of vanadium alloys to a fusion reactor blanket

    Energy Technology Data Exchange (ETDEWEB)

    Bethin, J.; Tobin, A. (Grumman Aerospace Corp., Bethpage, NY (USA). Research and Development Center)

    1984-05-01

    Vanadium and vanadium alloys are of interest in fusion reactor blanket applications due to their low induced radioactivity and outstanding elevated temperature mechanical properties during neutron irradiation. The major limitation to the use of vanadium is its sensitivity to oxygen impurities in the blanket environment, leading to oxygen embrittlement. A quantitative analysis was performed of the interaction of gaseous impurities in a helium coolant with vanadium and the V-15Cr-5Ti alloy under conditions expected in a fusion reactor blanket. It was shown that the use of unalloyed V would impose severe restrictions on the helium gas cleanup system due to excessive oxygen buildup and embrittlement of the metal. However, internal oxidation effects and the possibly lower terminal oxygen solubility in the alloy would impose much less severe cleanup constraints. It is suggested that V-15Cr-5Ti is a promising candidate for certain blanket applications and deserves further consideration.

  15. Assessment of vanadium alloys for ITER application

    International Nuclear Information System (INIS)

    Borgstedt, H.U.; Clemens, H.; Ehrlich, K.; Fromm, E.; Kelzenberg, S.; Moeslang, A.; Pick, M.; Ruehle, M.; Schaaf, B. van der; Schaefer, L.; Schiller, P.; Schirra, M.; Witwer, M.; Witzenburg, W. van; Zolti, E.; Zucchetti, M.

    1993-09-01

    The assessment effort concerned required evaluation of various relevant properties of vanadium alloys. The outcome predictably shows that these properties, as well as timing, funding, manufacturing and licensing aspects, each set their own specific boundary conditions for application of these alloys in ITER. Some of these are not really felt as constraints. Their capacity to accommodate high heat loads, for example, is better than other candidate materials and appears to be the main reason for the present interest in these alloys. Other favourable properties include neutronic properties (low nuclear heating rates, good tritium breeding performance and low helium generation rates), intrinsically low activation, excellent tensile and creep properties up to high temperatures and high strength-to-density ratio. Not all of these properties necessarily are relevant for ITER, but they would be important for longer term application. (orig.)

  16. Lithium diffusion in silver vanadium oxide

    International Nuclear Information System (INIS)

    Takeuchi, E.S.; Thiebolt, W.C. III

    1989-01-01

    Lithium/silver vanadium oxide (SVO) batteries have been developed to power implantable devices. The voltage of Li/SVO cells decreases with discharge allowing state of charge assessment by accurate determination of the cells' open circuit voltage. The open circuit voltage recovery of Li/SVO cells was monitored during intermittent high rate discharge. It was found that the voltage does not recover at the same rate or magnitude at all depths of discharge. The authors describe lithium diffusion in SVO studied by low scan rate voltammetry where utilization of SVO at various scan rates was used to determine the diffusion rate of lithium. A pulse technique was also used where the rate of lithium diffusion was measured at various depths of discharge

  17. On the superconductivity of vanadium based alloys

    International Nuclear Information System (INIS)

    Brouers, F.; Rest, J.V. der

    1985-01-01

    We have computed the electron density of States of solid solutions of vanadium based transition metal alloys V 90 X 10 by using the tight-binding recursion method for degenerate d-bands in order to calculte the alloy superconducting transition temperature with the McMillan formula. As observed experimentally for X on the left hand side of V in the periodic table one obtains an increase of T c while for X on the right hand side of V the critical temperature decreases. The detailed comparison with experiments indicate that when the bandwidths of the two constituents are different, one cannot neglect the variation of the electron-phonon interactions. (author) [pt

  18. Fourier transform of momentum distribution in vanadium

    International Nuclear Information System (INIS)

    Singh, A.K.; Manuel, A.A.; Peter, M.; Singru, R.M.

    1985-01-01

    Experimental Compton profile and 2D-angular correlation of positron annihilation radiation data from vanadium are analyzed by the mean of their Fourier transform. They are compared with the functions calculated with the help of both the linear muffin-tin orbital and the Hubbard-Mijnarends band structure methods. The results show that the functions are influenced by the positron wave function, by the e + -e - many-body correlations and by the differences in the electron wave functions used for the band structure calculations. It is concluded that Fourier analysis is a sensitive approach to investigate the momentum distributions in transition metals and to understnad the effects of the positron. (Auth.)

  19. Fluctuation conductivity of thin superconductive vanadium films

    International Nuclear Information System (INIS)

    Dmitrenko, I.M.; Sidorenko, A.S.; Fogel, N.Y.

    1982-01-01

    Resistive transitions into the superconductive state are studied in thin [d >T/sub c/ the experimental data on the excess conductivity of the films agree qualitatively and quantitively with Aslamazov--Larkin theory. There is no Maki--Thompson contribution to fluctuation conductivity. Near T/sub c/ the excess conductivity sigma' changes exponentially with temperature in accordance with the predictions of the theory of the critical fluctuations of the order parameter. The values of the effective charge carrier mass defined from data on sigma' for the low fluctuation and critical fluctuation regions differ markedly. This difference is within the spread of effective masses for various charge carrier groups already known for vanadium. Causes of the difference in resistive behavior for the regions T >T/sub c/ are considered

  20. The bioinorganic electrochemistry of vanadium-penicillamine complexes

    International Nuclear Information System (INIS)

    Bagal, U.A.; Riechel, T.L.

    1989-01-01

    Vanadium (V) has been found to inhibit (Na + , K + )-ATPase in the sodium pump reaction in erythrocytes. Glutathione has been suggested as the reducing agent that reverses the effect by reducing vanadium to the (IV) oxidation state. Penicillamine is being studied as a model for glutathione since both have sulfhydryl groups which are involved in redox and coordination chemistry. The electrochemistry in DMSO of penicillamine, its carboxylic ester, and their VO 2 + complexes are discussed in this paper

  1. Impurity states of vanadium in cadmium and zinc tellurides

    International Nuclear Information System (INIS)

    Gnatenko, Yu.P.; Farina, I.A.

    1996-01-01

    Low-temperature optical (4.5 K) and photoelectrical properties of CdTe and ZnTe crystals doped by vanadium are invetigated. The energies of carrier transition to valence and conduction bands, Mott-Habbard energy for 3d 3 -ion vanadium in both crystals are determined. The resonance of the excited 4 T l ( 4 P)-state of V 2+ -ion with the conduction band of CdTe crystal is found. 8 bibl.; 4 figs

  2. Intercalation compounds of vanadium(5) phosphates with glycerol

    International Nuclear Information System (INIS)

    Yakovleva, T.N.; Vykhodtseva, K.I.; Tarasova, D.V.; Soderzhinova, M.M.

    1997-01-01

    Interaction products of glycerol aqueous solutions with vanadium(5) phosphates were investigated by the methods of ESR, X-ray phase and thermal analyses. It is shown that glycerol molecules enter the interlayer space of VOPO 4 · 2H 2 O lattice with formation of disordered intercalated compounds with glycerol on the basis of partially reduced vanadium phosphate form when using α-VOPO 4 . 16 refs., 4 figs., 1 tab

  3. Metal-insulator transition in vanadium dioxide

    International Nuclear Information System (INIS)

    Zylbersztejn, A.; Mott, N.F.

    1975-01-01

    The basic physical parameters which govern the metal-insulator transition in vanadium dioxide are determined through a review of the properties of this material. The major importance of the Hubbard intra-atomic correlation energy in determining the insulating phase, which was already evidence by studies of the magnetic properties of V 1 -/subx/Cr/subx/O 2 alloys, is further demonstrated from an analysis of their electrical properties. An analysis of the magnetic susceptibility of niobium-doped VO 2 yields a picture for the current carrier in the low-temperature phase in which it is accompanied by a spin cloud (owing to Hund's-rule coupling), and has therefore an enhanced mass (m approx. = 60m 0 ). Semiconducting vanadium dioxide turns out to be a borderline case for a classical band-transport description; in the alloys at high doping levels, Anderson localization with hopping transport can take place. Whereas it is shown that the insulating phase cannot be described correctly without taking into account the Hubbard correlation energy, we find that the properties of the metallic phase are mainly determined by the band structure. Metallic VO 2 is, in our view, similar to transition metals like Pt or Pd: electrons in a comparatively wide band screening out the interaction between the electrons in a narrow overlapping band. The magnetic susceptibility is described as exchange enhanced. The large density of states at the Fermi level yields a substantial contribution of the entropy of the metallic electrons to the latent heat. The crystalline distortion removes the band degeneracy so that the correlation energy becomes comparable with the band width and a metal-insulator transition takes place

  4. Nickel and vanadium extraction from the Syrian petroleum coke

    International Nuclear Information System (INIS)

    Shlewit, H.; Alibrahim, M.

    2007-01-01

    Syrian petroleum coke samples were characterized and submitted for salt-roasting treatment in electric furnace to evaluate the convenience of this procedure for the extraction of the vanadium, nickel and sulfur from coke. Both solution and solid residue remaining after salt roasting were separated by filtration and were analyzed for vanadium, nickel and sulfur. The solution was analyzed by UV-Visible spectroscopy for vanadium and nickel and gravimetrically for sulfur. The solid residue and the untreated samples of petroleum coke were analyzed by XRF spectrometry. Results showed that more than 90% of sulfur and 60% of vanadium could be extracted by salt roasting treatment. An alternative procedure has been suggested, in which, more than 80% of sulfur and small percentage of vanadium can be leached by 0.75 M of Na 2 CO 3 solution at 70-80 Co. Vanadium was selectively extracted by DEHPA/TBP from the loaded leached solution. The extraction procedure flowsheet was also suggested. (authors)

  5. Recycling of Ammonia Wastewater During Vanadium Extraction from Shale

    Science.gov (United States)

    Shi, Qihua; Zhang, Yimin; Liu, Tao; Huang, Jing

    2018-03-01

    In the vanadium metallurgical industry, massive amounts of ammonia hydroxide or ammonia salt are added during the precipitation process to obtain V2O5; therefore, wastewater containing a high level of NH4 + is generated, which poses a serious threat to environmental and hydrologic safety. In this article, a novel process was developed to recycle ammonia wastewater based on a combination of ammonia wastewater leaching and crystallization during vanadium extraction from shale. The effects of the NH4 + concentration, temperature, time and liquid-to-solid ratio on the leaching efficiencies of vanadium, aluminum and potassium were investigated, and the results showed that 93.2% of vanadium, 86.3% of aluminum and 96.8% of potassium can be leached from sulfation-roasted shale. Subsequently, 80.6% of NH4 + was separated from the leaching solution via cooling crystallization. Vanadium was recovered via a combined method of solvent extraction, precipitation and calcination. Therefore, ammonia wastewater was successfully recycled during vanadium extraction from shale.

  6. Sensitivity Calculation of Vanadium Self-Powered Neutron Detector

    International Nuclear Information System (INIS)

    Cha, Kyoon Ho

    2011-01-01

    Self-powered neutron detector (SPND) is being widely used to monitor the reactor core of the nuclear power plants. The SPND contains a neutron-sensitive metallic emitter surrounded by a ceramic insulator. Currently, the rhodium SPND has been used in many nuclear power plants. The lifetime of rhodium is too short (about 3∼5 years) to operate the nuclear power plant economically. The vanadium (V) SPND is also primarily sensitive to neutrons like rhodium, but is a somewhat slower reaction time as that of a rhodium SPND. The benefit of vanadium over rhodium is its low depletion rate, which is a factor of 7 times less than that of rhodium. For this reason, a vanadium SPND has been being developed to replace the rhodium SPND which is used in OPR1000. Some Monte Carlo simulations were accomplished to calculate the initial sensitivity of vanadium emitter material and alumina (Al 2 O 3 ) insulator with a cylindrical geometry. An MCNP-X code was used to simulate some factors (neutron self shielding factor and electron escape probability from the emitter) necessary to calculate the sensitivity of vanadium detector. The simulation results were compared with some theoretical and experimental values. The method presented here can be used to analyze the optimum design of the vanadium SPND

  7. Tackling capacity fading in vanadium flow batteries with amphoteric membranes

    Science.gov (United States)

    Oldenburg, Fabio J.; Schmidt, Thomas J.; Gubler, Lorenz

    2017-11-01

    Capacity fading and poor electrolyte utilization caused by electrolyte imbalance effects are major drawbacks for the commercialization of vanadium flow batteries (VFB). The influence of membrane type (cationic, anionic, amphoteric) on these effects is studied by determining the excess and net flux of each vanadium ion in an operating VFB assembled with a cation exchange membrane (CEM), Nafion® NR212, an anion exchange membrane (AEM), Fumatech FAP-450, and an amphoteric ion exchange membrane (AIEM) synthesized in-house. It is shown that the net vanadium flux, accompanied by water transport, is directed towards the positive side for the CEM and towards the negative side for the AEM. The content of cation and anion exchange groups in the AIEM is adjusted via radiation grafting to balance the vanadium flux between the two electrolyte sides. With the AIEM the net vanadium flux is significantly reduced and capacity fading due to electrolyte imbalances can be largely eliminated. The membrane's influence on electrolyte imbalance effects is characterized and quantified in one single charge-discharge cycle by analyzing the content of the four different vanadium species in the two electrolytes. The experimental data recorded herewith conclusively explains the electrolyte composition after 80 cycles.

  8. Chloride supporting electrolytes for all-vanadium redox flow batteries.

    Science.gov (United States)

    Kim, Soowhan; Vijayakumar, M; Wang, Wei; Zhang, Jianlu; Chen, Baowei; Nie, Zimin; Chen, Feng; Hu, Jianzhi; Li, Liyu; Yang, Zhenguo

    2011-10-28

    This paper examines vanadium chloride solutions as electrolytes for an all-vanadium redox flow battery. The chloride solutions were capable of dissolving more than 2.3 M vanadium at varied valence states and remained stable at 0-50 °C. The improved stability appeared due to the formation of a vanadium dinuclear [V(2)O(3)·4H(2)O](4+) or a dinuclear-chloro complex [V(2)O(3)Cl·3H(2)O](3+) in the solutions over a wide temperature range. The all-vanadium redox flow batteries with the chloride electrolytes demonstrated excellent reversibility and fairly high efficiencies. Only negligible, if any, gas evolution was observed. The improved energy capacity and good performance, along with the ease in heat management, would lead to substantial reduction in capital cost and life-cycle cost, making the vanadium chloride redox flow battery a promising candidate for stationary applications. This journal is © the Owner Societies 2011

  9. Roasting and leaching behaviors of vanadium and chromium in calcification roasting-acid leaching of high-chromium vanadium slag

    Science.gov (United States)

    Wen, Jing; Jiang, Tao; Zhou, Mi; Gao, Hui-yang; Liu, Jia-yi; Xue, Xiang-xin

    2018-05-01

    Calcification roasting-acid leaching of high-chromium vanadium slag (HCVS) was conducted to elucidate the roasting and leaching behaviors of vanadium and chromium. The effects of the purity of CaO, molar ratio between CaO and V2O5 ( n(CaO)/ n(V2O5)), roasting temperature, holding time, and the heating rate used in the oxidation-calcification processes were investigated. The roasting process and mechanism were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetry-differential scanning calorimetry (TG-DSC). The results show that most of vanadium reacted with CaO to generate calcium vanadates and transferred into the leaching liquid, whereas almost all of the chromium remained in the leaching residue in the form of (Fe0.6Cr0.4)2O3. Variation trends of the vanadium and chromium leaching ratios were always opposite because of the competitive reactions of oxidation and calcification between vanadium and chromium with CaO. Moreover, CaO was more likely to combine with vanadium, as further confirmed by thermodynamic analysis. When the HCVS with CaO added in an n(CaO)/ n(V2O5) ratio of 0.5 was roasted in an air atmosphere at a heating rate of 10°C/min from room temperature to 950°C and maintained at this temperature for 60 min, the leaching ratios of vanadium and chromium reached 91.14% and 0.49%, respectively; thus, efficient extraction of vanadium from HCVS was achieved and the leaching residue could be used as a new raw material for the extraction of chromium. Furthermore, the oxidation and calcification reactions of the spinel phases occurred at 592 and 630°C for n(CaO)/ n(V2O5) ratios of 0.5 and 5, respectively.

  10. Ion sensing properties of vanadium/tungsten mixed oxides

    International Nuclear Information System (INIS)

    Guidelli, Eder Jose; Guerra, Elidia Maria; Mulato, Marcelo

    2011-01-01

    Vanadium/tungsten mixed oxide (V 2 O 5 /WO 3 ) 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 V 2 O 5 after the insertion of WO 3 revealing that the lamellar structure is under compressive stress. The crystallinity increases with increasing WO 3 molar ratio. The film is not homogeneous, with more WO 3 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% WO 3 molar ratio. For higher WO 3 molar ratios, the behavior is not linear. It can be concluded that V 2 O 5 dominates for acidic solutions while WO 3 dominates for basic solutions. Therefore, the mixed oxide with low amount of WO 3 is the main candidate for further use as biosensor.

  11. Stress relaxation in vanadium under shock and shockless dynamic compression

    International Nuclear Information System (INIS)

    Kanel, G. I.; Razorenov, S. V.; Garkushin, G. V.; Savinykh, A. S.; Zaretsky, E. B.

    2015-01-01

    Evolutions of elastic-plastic waves have been recorded in three series of plate impact experiments with annealed vanadium samples under conditions of shockless and combined ramp and shock dynamic compression. The shaping of incident wave profiles was realized using intermediate base plates made of different silicate glasses through which the compression waves were entered into the samples. Measurements of the free surface velocity histories revealed an apparent growth of the Hugoniot elastic limit with decreasing average rate of compression. The growth was explained by “freezing” of the elastic precursor decay in the area of interaction of the incident and reflected waves. A set of obtained data show that the current value of the Hugoniot elastic limit and plastic strain rate is rather associated with the rate of the elastic precursor decay than with the local rate of compression. The study has revealed the contributions of dislocation multiplications in elastic waves. It has been shown that independently of the compression history the material arrives at the minimum point between the elastic and plastic waves with the same density of mobile dislocations

  12. Electrical and optical properties of highly oriented nanocrystalline vanadium pentoxide

    International Nuclear Information System (INIS)

    Bahgat, A.A.; Ibrahim, F.A.; El-Desoky, M.M.

    2005-01-01

    Highly oriented nanocrystalline hydrated vanadium pentoxide, V 2 O 5 .nH 2 O, were grown epitaxially on a glass substrate along the c-axis to form a film of 200 nm thick. The films were prepared by dissolving V 2 O 5 powder in hydrogen peroxide, H 2 O 2 , solution. X-ray diffraction, transmission electron micrograph and electron diffraction were used to identify the structure of the obtained nanocrystals. Homogenous nanocrystals of 7.0 ± 1.0 nm in size were obtained and were closed packed and are distributed evenly. Electrical conductivity and thermoelectric power were measured in the temperature range 300-480 K for the as prepared films parallel to the substrate surface; i.e. normal to the c-axis. The obtained results showed an n-type semiconducting behavior within the whole temperature range. It is also clear to see that a reversible abnormality at about 340 K is realized during the cooling electrical conductivity measurements. On the other hand, optical transmission and reflection were used to evaluate different optical parameters such as; optical band gap, nature of donor levels and different absorption bands parameters. Both the electrical and optical data are correlated and accordingly the conduction mechanism is verified. Electronic parameters such as effective mass, carriers' type and concentration and drift mobility were evaluated

  13. Nitrogen-Doped Carbon Nanotube/Graphite Felts as Advanced Electrode Materials for Vanadium Redox Flow Batteries.

    Science.gov (United States)

    Wang, Shuangyin; Zhao, Xinsheng; Cochell, Thomas; Manthiram, Arumugam

    2012-08-16

    Nitrogen-doped carbon nanotubes have been grown, for the first time, on graphite felt (N-CNT/GF) by a chemical vapor deposition approach and examined as an advanced electrode for vanadium redox flow batteries (VRFBs). The unique porous structure and nitrogen doping of N-CNT/GF with increased surface area enhances the battery performance significantly. The enriched porous structure of N-CNTs on graphite felt could potentially facilitate the diffusion of electrolyte, while the N-doping could significantly contribute to the enhanced electrode performance. Specifically, the N-doping (i) modifies the electronic properties of CNT and thereby alters the chemisorption characteristics of the vanadium ions, (ii) generates defect sites that are electrochemically more active, (iii) increases the oxygen species on CNT surface, which is a key factor influencing the VRFB performance, and (iv) makes the N-CNT electrochemically more accessible than the CNT.

  14. Comparison of Ultrasound-Assisted and Regular Leaching of Vanadium and Chromium from Roasted High Chromium Vanadium Slag

    Science.gov (United States)

    Wen, Jing; Jiang, Tao; Gao, Huiyang; Liu, Yajing; Zheng, Xiaole; Xue, Xiangxin

    2018-02-01

    Ultrasound-assisted leaching (UAL) was used for vanadium and chromium leaching from roasted material obtained by the calcification roasting of high-chromium-vanadium slag. UAL was compared with regular leaching. The effect of the leaching time and temperature, acid concentration, and liquid-solid ratio on the vanadium and chromium leaching behaviors was investigated. The UAL mechanism was determined from particle-size-distribution and microstructure analyses. UAL decreased the reaction time and leaching temperature significantly. Furthermore, 96.67% vanadium and less than 1% chromium were leached at 60°C for 60 min with 20% H2SO4 at a liquid-solid ratio of 8, which was higher than the maximum vanadium leaching rate of 90.89% obtained using regular leaching at 80°C for 120 min. Ultrasonic waves broke and dispersed the solid sample because of ultrasonic cavitation, which increased the contact area of the roasted sample and the leaching medium, the solid-liquid mass transfer, and the vanadium leaching rate.

  15. Hydrogen spillover on DV (555-777) graphene – vanadium cluster system: First principles study

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, E. Mathan, E-mail: ranjit.t@res.srmuniv.ac.in, E-mail: mathanranjitha@gmail.com; Thapa, Ranjit, E-mail: ranjit.t@res.srmuniv.ac.in, E-mail: mathanranjitha@gmail.com [SRM Research Institute, SRM University, Kattankulathur, Tamil Nadu - 603203 (India); P, Sabarikirishwaran [Department of Physics and Nanotechnology, SRM University, Kattankulathur, Tamil Nadu - 603203 (India)

    2015-06-24

    Using dispersion corrected density functional theory (DFT+D), the interaction of Vanadium adatom and cluster with divacancy (555-777) defective graphene sheet has been studied elaborately. We explore the prospect of hydrogen storage on V{sub 4} cluster adsorbed divacancy graphene system. It has been observed that V{sub 4} cluster (acting as a catalyst) can dissociate the H{sub 2} molecule into H atoms with very low barrier energy. We introduce the spillover of the atomic hydrogen throughout the surface via external mediator gallane (GaH{sub 3}) to form a hydrogenated system.

  16. Influence of structure of carrier (silica gel) on texture and catalytic properties of vanadium catalysts for sulfur dioxide oxidation

    International Nuclear Information System (INIS)

    Simonova, L.G.; Fenelonov, V.B.; Dzis'ko, V.A.; Noskova, S.P.; Kryukova, G.N.; Litvak, G.S.

    1982-01-01

    The influence of initial porous structure of a carrier-silica gel on texture and catalytic properties of vanadium catalysts is considered. It is shown that low thermal stability of the carrier results not only in considerable decrease of the catalyst surface during heat treatment but also in blocking part of active component in locked pores which accounts for the activity decrease in kinetic region and formation of active component forms that can not be extracted by acid

  17. Deposition of single-layer and graded aluminum nitride coatings on vanadium substrates using ion-beam assisted reactive evaporation (ITER task no. ETA-EC-BLR26)

    International Nuclear Information System (INIS)

    Jamarani, F.; Lang, R.; Owles, R.

    1994-06-01

    The objective of the project has been to develop a reactive evaporation process for the fabrication of aluminum nitride coatings on pure vanadium substrates. The aluminum nitride coatings are to be used as electrical insulators on the surfaces of structural materials in contact with liquid metal coolants. (author). 9 refs., 2 tabs., 5 figs

  18. Complexation of vanadium with amidoxime and carboxyl groups. Uncovering the competitive role of vanadium in uranium extraction from seawater

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Cong-Zhi; Wu, Qun-Yan; Lan, Jian-Hui; Shi, Wei-Qun [Chinese Academy of Sciences, Beijing (China). Inst. of High Energy Physics; Chai, Zhi-Fang [Chinese Academy of Sciences, Beijing (China). Inst. of High Energy Physics; Soochow Univ., Suzhou (China). School of Radiological and Interdisciplinary Sciences (RAD-X); Wu, Guo-Zhong [Chinese Academy of Sciences, Shanghai (China). Shanghai Inst. of Applied Physics

    2017-09-01

    At present, amidoxime-based adsorbents are considered to be the most promising materials for extraction of uranium from seawater. However, the high concentrations of transition metals especially vanadium strongly compete with uranium in the sequestration process, which is extremely limited the commercial use of amidoxime-based adsorbents. In this work, the coordination modes, bonding nature, and stabilities of possible vanadium(IV) (VO{sup 2+}) and (V) (VO{sub 2}{sup +}, VO{sup 3+}, V{sup 5+}) complexes with amidoximate (AO{sup -}), carboxyl (Ac{sup -}), glutarimidedioximate (HA{sup -}) and deprotonated glutarimidedioximate (A{sup 2-}) on single and double alkyl chains (R=C{sub 13}H{sub 26}) are systematically explored by quantum chemical calculations. Different from the uranyl (UO{sub 2}{sup 2+}) complexes, the AO{sup -} groups of the vanadium(IV) and (V) complexes prefer to coordinate as monodentate and chelate ligands, while few species with AO{sup -} groups in η{sup 2}-binding mode have been observed in the vanadium complexes. Besides, the vanadium complexes are predicted to have obvious covalent metal-ligand bonds. According to thermodynamic stability analysis, all the vanadium complexes with AO{sup -}, Ac{sup -}, HA{sup -} and A{sup 2-} ligands on double alkyl chains are found to be more stable than corresponding complexes with ligands on a single chain. The synergistic effect of the amidoxime and carboxyl groups can be observed in most of VO{sub 2}{sup +} and VO{sup 3+} complexes with mixed ligands (AO{sup -}/Ac{sup -}). The vanadium(IV) and (V) complexes are more stable than the corresponding uranyl complexes, and the adsorption capability of the amidoxime-based adsorbents toward vanadium(V) ions decrease in the order of VO{sub 2}{sup +}>VO{sup 3+}> V{sup 5+}. The dioxovanadium cation VO{sub 2}{sup +} is predicted to form multinuclear vanadium complex in the sequestration process, possibly resulting in higher stable VO{sub 2}{sup +} complexes. Therefore

  19. Graphite-graphite oxide composite electrode for vanadium redox flow battery

    International Nuclear Information System (INIS)

    Li Wenyue; Liu Jianguo; Yan Chuanwei

    2011-01-01

    Highlights: → A new composite electrode is designed for vanadium redox flow battery (VRB). → The graphite oxide (GO) is used as electrode reactions catalyst. → The excellent electrode activity is attributed to the oxygen-containing groups attached on the GO surface. → A catalytic mechanism of the GO towards the redox reactions is presumed. - Abstract: A graphite/graphite oxide (GO) composite electrode for vanadium redox battery (VRB) was prepared successfully in this paper. The materials were characterized with X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The specific surface area was measured by the Brunauer-Emmett-Teller method. The redox reactions of [VO 2 ] + /[VO] 2+ and V 3+ /V 2+ were studied with cyclic voltammetry and electrochemical impedance spectroscopy. The results indicated that the electrochemical performances of the electrode were improved greatly when 3 wt% GO was added into graphite electrode. The redox peak currents of [VO 2 ] + /[VO] 2+ and V 3+ /V 2+ couples on the composite electrode were increased nearly twice as large as that on the graphite electrode, and the charge transfer resistances of the redox pairs on the composite electrode are also reduced. The enhanced electrochemical activity could be ascribed to the presence of plentiful oxygen functional groups on the basal planes and sheet edges of the GO and large specific surface areas introduced by the GO.

  20. Nanorod niobium oxide as powerful catalysts for an all vanadium redox flow battery.

    Science.gov (United States)

    Li, Bin; Gu, Meng; Nie, Zimin; Wei, Xiaoliang; Wang, Chongmin; Sprenkle, Vincent; Wang, Wei

    2014-01-08

    A powerful low-cost electrocatalyst, nanorod Nb2O5, is synthesized using the hydrothermal method with monoclinic phases and simultaneously deposited on the surface of a graphite felt (GF) electrode in an all vanadium flow battery (VRB). Cyclic voltammetry (CV) study confirmed that Nb2O5 has catalytic effects toward redox couples of V(II)/V(III) at the negative side and V(IV)/V(V) at the positive side to facilitate the electrochemical kinetics of the vanadium redox reactions. Because of poor conductivity of Nb2O5, the performance of the Nb2O5 loaded electrodes is strongly dependent on the nanosize and uniform distribution of catalysts on GF surfaces. Accordingly, an optimal amount of W-doped Nb2O5 nanorods with minimum agglomeration and improved distribution on GF surfaces are established by adding water-soluble compounds containing tungsten (W) into the precursor solutions. The corresponding energy efficiency is enhanced by ∼10.7% at high current density (150 mA·cm(-2)) as compared with one without catalysts. Flow battery cyclic performance also demonstrates the excellent stability of the as prepared Nb2O5 catalyst enhanced electrode. These results suggest that Nb2O5-based nanorods, replacing expensive noble metals, uniformly decorating GFs holds great promise as high-performance electrodes for VRB applications.

  1. Nanocomposites based on hierarchical porous carbon fiber@vanadium nitride nanoparticles as supercapacitor electrodes.

    Science.gov (United States)

    Ran, Fen; Wu, Yage; Jiang, Minghuan; Tan, Yongtao; Liu, Ying; Kong, Lingbin; Kang, Long; Chen, Shaowei

    2018-03-28

    In this study, a hybrid electrode material for supercapacitors based on hierarchical porous carbon fiber@vanadium nitride nanoparticles is fabricated using the method of phase-separation mediated by the PAA-b-PAN-b-PAA tri-block copolymer. In the phase-separation procedure, the ionic block copolymer self-assembled on the surface of carbon nanofibers, and is used to adsorb NH 4 VO 3 . Thermal treatment at controlled temperatures under an NH 3  : N 2 atmosphere led to the formation of vanadium nitride nanoparticles that are distributed uniformly on the nanofiber surface. By changing the PAN to PAA-b-PAN-b-PAA ratio in the casting solution, a maximum specific capacitance of 240.5 F g -1 is achieved at the current density of 0.5 A g -1 with good rate capability at a capacitance retention of 72.1% at 5.0 A g -1 in an aqueous electrolyte of 6 mol L -1 KOH within the potential range of -1.10 to 0 V (rN/A = 1.5/1.0). Moreover, an asymmetric supercapacitor is assembled by using the hierarchical porous carbon fiber@vanadium nitride as the negative electrode and Ni(OH) 2 as the positive electrode. Remarkably, at the power density of 400 W kg -1 , the supercapacitor device delivers a better energy density of 39.3 W h kg -1 . It also shows excellent electrochemical stability, and thus might be used as a promising energy-storage device.

  2. Vanadium-Catalyzed Enantioselective Desymmetrization of meso-Secondary Allylic Alcohols and Homoallylic Alcohols

    OpenAIRE

    Li, Zhi; Zhang, Wei; Hisashi Yamamoto, H.

    2008-01-01

    Vanadium-catalyzed epoxidation has extended substrate scope. In addition to various bis-allylic alcohols, bis-homoallylic alcohols can also be desymmetrized using our Vanadium-Bis-hydroxamic acid complexes.

  3. Improving methane gas sensing properties of multi-walled carbonnanotubes by vanadium oxide filling

    CSIR Research Space (South Africa)

    Chimowa, George

    2017-08-01

    Full Text Available Manipulation of electrical properties and hence gas sensing properties of multi-walled carbon nanotubes (MWNTs) by filling the inner wall with vanadium oxide is presented. Using a simple capillary technique, MWNTs are filled with vanadium metal...

  4. Interaction of slow electrons with surfaces. II

    International Nuclear Information System (INIS)

    Komolov, S.A.; Chadderton, L.T.

    1976-01-01

    Total current spectroscopy (TCS) has been used to study the growth of films of gold and silver on (100) vanadium surfaces. A slow transition from TCS curves characteristic of vanadium to curves characteristic of the noble metals is observed, accompanied by an increase in the net work function - more rapid for silver than for gold. Vanadium characteristics are lost from the TCS curves for mean overlayer thicknesses > approximately 15A, and a simple analysis shows that the thickness of the surface zone from which TCS signals originate is approximately given by the electron mean free path. Observations of progressive attenuation of a characteristic vanadium feature with increasing mean thickness of overlayer permits separation into stages of nucleation and growth. There is a critical nucleus size of approximately 2A for silver and approximately 4A for gold. (Auth.)

  5. Effect of drying method on properties of vanadium-molybdenum oxide catalysts

    International Nuclear Information System (INIS)

    Gorshkova, T.P.; Savchenko, L.A.; Tarasova, D.V.; Tret'yakov, Yu.D.; Olen'kova, I.P.; Nikoro, T.A.; Maksimov, N.G.

    1981-01-01

    Effect of drying method of molybdenum and vanadium salt solutions on physicochemical and catalytical properties of vanadium-molybdenum catalysts is studied. It is shown that the drying method of solutions determines the completeness of vanadium binding into oxide vanadium-molybdenum compounds and thus effects the activity and selectivity of catalysts in acrolein oxidation into acrylic acid. Besides the drying method determines the porous structure of catalysts [ru

  6. Structural and silver/vanadium ratio effects on silver vanadium phosphorous oxide solution formation kinetics: impact on battery electrochemistry.

    Science.gov (United States)

    Bock, David C; Takeuchi, Kenneth J; Marschilok, Amy C; Takeuchi, Esther S

    2015-01-21

    The detailed understanding of non-faradaic parasitic reactions which diminish battery calendar life is essential to the development of effective batteries for use in long life applications. The dissolution of cathode materials including manganese, cobalt and vanadium oxides in battery systems has been identified as a battery failure mechanism, yet detailed dissolution studies including kinetic analysis are absent from the literature. The results presented here provide a framework for the quantitative and kinetic analyses of the dissolution of cathode materials which will aid the broader community in more fully understanding this battery failure mechanism. In this study, the dissolution of silver vanadium oxide, representing the primary battery powering implantable cardioverter defibrillators (ICD), is compared with the dissolution of silver vanadium phosphorous oxide (Ag(w)VxPyOz) materials which were targeted as alternatives to minimize solubility. This study contains the first kinetic analyses of silver and vanadium solution formation from Ag0.48VOPO4·1.9H2O and Ag2VP2O8, in a non-aqueous battery electrolyte. The kinetic results are compared with those of Ag2VO2PO4 and Ag2V4O11 to probe the relationships among crystal structure, stoichiometry, and solubility. For vanadium, significant dissolution was observed for Ag2V4O11 as well as for the phosphate oxide Ag0.49VOPO4·1.9H2O, which may involve structural water or the existence of multiple vanadium oxidation states. Notably, the materials from the SVPO family with the lowest vanadium solubility are Ag2VO2PO4 and Ag2VP2O8. The low concentrations and solution rates coupled with their electrochemical performance make these materials interesting alternatives to Ag2V4O11 for the ICD application.

  7. Determination of vanadium in Syrian commercial and raffinate phosphoric acid

    International Nuclear Information System (INIS)

    Al-Merey, R.

    2002-04-01

    This study presents two methods for vanadium determination in Syrian commercial phosphoric acid. The vanadium (V) in the oxidized commercial phosphoric acid by ammonium persulfate solution is extracted from 5-M hydrochloride acid medium using N-benzoyl-N-phenyl hydroxyl amine (BPHA) in chloroform as an extracting solution. The first method, the extract vanadium as VOL 2 Cl is changed to V 2 O 3 L 4 complex by the addition of benzimidazole in 1-butanol to the violet organic layer. The absorbance is then measured at 440 nm (the molar absorptivity was found to be 3865 M -1 cm -1 ), where Beer law is applicable up to 36-μg ml -1 . the accuracy, precision and detection limit were found to be 3.7%, 77 ppb and 37 ppb, respectively. the second method, the organic layer is heated to evaporate chloroform, the residue is digested using 20% ammonium persulfate and 2-M sulfuric acid solutions. The vanadium concentration is measured spectrophotometrically by oxidizing gallic acid with persulfate (S 2 O 8 2- ) anion in phosphoric acid medium, where the vanadium (V) acts as a catalyst in the oxidation reaction. This method has a high sensitivity (∼10 -12 ) with accuracy and precision 5% and 0.621 ppb, respectively. Also Beer law at λ m ax=415 nm (ε=∼2 x 10 6 M -1 ) is applicable in the range 2.58-33.3 ppb. (author)

  8. Absorption of hydrogen by vanadium-palladium alloys

    International Nuclear Information System (INIS)

    Artman, D.; Lynch, J.F.; Flanagan, T.B.

    1976-01-01

    Pressure composition isotherms (273-373 K) have been determined for the absorption of hydrogen by a series of six palladium alloys (f.c.c) in the composition range from 1 to 8 at.% vanadium. At a given hydrogen content, the equilibrium hydrogen pressure progressively increases with vanadium content. Thermodynamic parameters for the absorption of hydrogen are reported at infinite dilution of hydrogen and for the formation of the nonstoichiometric hydride from the hydrogen-saturated alloy. The relative, partial molar enthalpy of solution of hydrogen at infinite dilution increases slightly with vanadium content. The presence of vanadium, which absorbs hydrogen itself in its normal b.c.c. structure, greatly inhibits the ability of palladium to absorb hydrogen. For example, the isobaric solubility of hydrogen (1 atm, 298K) decreases from H/Pd=0.7 (palladium) to 0.024 (V(6%)-Pd). The lattice expansion due to the presence of interstitial hydrogen has been determined by X-ray diffraction. From these data it can be concluded that the formation of two non-stoichiometric hydride phases does not occur at vanadium contents greater that 5 at.% (298 K). Electrical resistance has been measured as a function of the hydrogen content of the alloys. The electrical resistance increases more markedly with hydrogen content for these alloys than for any of the palladium alloys previously examined. (Auth.)

  9. Electrochemical studies on vanadium oxides, 9

    International Nuclear Information System (INIS)

    Miura, Takashi; Yamamoto, Masahiro; Takahashi, Hirobumi; Kishi, Tomiya; Nagai, Takashi

    1979-01-01

    The mechanism of the anodic oxidation of various organic compounds-including methanol, formaldehyde, formic acid, ethanol, acetaldehyde and acetic acid-at illuminated vanadium pentoxide (V 2 O 5 ) single crystal electrodes were investigated in aqueous solutions of an H 2 SO 4 -K 2 SO 4 system of about pH 2, in which oxygen evolution from water molecules had previously been confirmed to occur with a current efficiency of about 100%. It was shown that all the organics were oxidized by the so called hole-current doubling mechanism, and that the oxygen evolution reaction, which competed with the above oxidation reaction at the hole-capturing step from the valence band of the electrode, proceeded by the simple hole-capturing mechanism, not followed by an electron injection step into the conduction band. Furthermore, it is considered that chloride ions added to the electrolytes tended to hinder hole-current doubling oxidation owing to their reactivity with the holes at the illuminated V 2 O 5 electrodes. (author)

  10. Critical currents in columnar vanadium films

    International Nuclear Information System (INIS)

    Cherkasova, V.G.; Kolin'ko, A.E.; Slatin, A.E.; Fogel, N.Y.

    1982-01-01

    The angular dependence of the critical current I/sub c/ is studied in columnar vanadium films. In measurements in constant magnetic fields an anomalous maximum I/sub c/ is found on the I/sub c/(theta) curves at arbitrary values of the external magnetic field and temperature, when the magnetic field is perpendicular to the plane of the specimen. The angular dependence of I/sub c/ measured in constant reduced magnetic fields h = H/H/sub c/2(T,theta) shows no singularities in the vicinity of the angle at which the I/sub c/ peak is found in the case H = const, i.e., the critical current is isotropic. This implies that a change in the relative orientation of the vortices and column boundaries produces no change in critical current. The experimental data obtained permit the conclusion that the anisotropy of I/sub c/ observed in a constant magnetic field H is merely a consequence of the anisotropy of the critical magnetic field H/sub c/: the critical current ''tracking'' the magnitude and angular dependence of H/sub c/

  11. Membrane development for vanadium redox flow batteries.

    Science.gov (United States)

    Schwenzer, Birgit; Zhang, Jianlu; Kim, Soowhan; Li, Liyu; Liu, Jun; Yang, Zhenguo

    2011-10-17

    Large-scale energy storage has become the main bottleneck for increasing the percentage of renewable energy in our electricity grids. Redox flow batteries are considered to be among the best options for electricity storage in the megawatt range and large demonstration systems have already been installed. Although the full technological potential of these systems has not been reached yet, currently the main problem hindering more widespread commercialization is the high cost of redox flow batteries. Nafion, as the preferred membrane material, is responsible for about 11% of the overall cost of a 1 MW/8 MWh system. Therefore, in recent years two main membrane related research threads have emerged: 1) chemical and physical modification of Nafion membranes to optimize their properties with regard to vanadium redox flow battery (VRFB) application; and 2) replacement of the Nafion membranes with different, less expensive materials. This review summarizes the underlying basic scientific issues associated with membrane use in VRFBs and presents an overview of membrane-related research approaches aimed at improving the efficiency of VRFBs and making the technology cost-competitive. Promising research strategies and materials are identified and suggestions are provided on how materials issues could be overcome.

  12. Concentration of vanadium in crude oil and water using inductively-coupled plasma spectrometry

    International Nuclear Information System (INIS)

    Amin, Y.M.; Hassan, M.A.; Junkin, K.; Mahat, R.H.; Raphie, B.

    1991-01-01

    Vanadium is a trace element that is usually associated to crude oil and its products. In this study the concentration of vanadium in a few samples of local crude oil, sea and river water were determined using inductively-coupled plasma spectrometry (ICP). It is hoped that the concentration of vanadium in water can be used to indicate the possible extent of oil contamination

  13. Chemistry, spectroscopy and the role of supported vanadium oxides in heterogeneous catalysis

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Keller, D.E.

    2003-01-01

    Supported vanadium oxide catalysts are active in a wide range of applications. In this review, an overview is given of the current knowledge available about vanadium oxide-based catalysts. The review starts with the importance of vanadium in heterogeneous catalysis, a discussion of the molecular

  14. Process of coke less without waste treatment of direct vanadium allowing steel melting

    International Nuclear Information System (INIS)

    Lisienko, V.G.; Droujinina, O.G.; Morozova, V.A.; Ladigina, N.V.; Yusfin, Yu.S.; Parenkev, A.E.

    2003-01-01

    The development of new methods of steel production are now conducted with the purpose of energy consumption and harmful emissions reduction. The choice of technology and equipment in this case plays a marginal role. It is well known that vanadium alloying steel has increased service properties. The known classical scheme of vanadium steel melting is very power-intensive, as includes such power-intensive processes as blast furnace process and chemical processing of vanadium slag therewith sintering and by-product coke processes are accompanied by significant harmful emissions. In so doing the vanadium losses may run to 60%. In view of requests of environment protection and economical efficiency the new process of coke less without wastes processing of vanadium-bearing raw material with direct vanadium allowing of steel - LP-process is developed. Its purpose is the melting on the basis of vanadium-bearing titanomagnetite of vanadium allowing steel with increase of vanadium concentration in steel and diminution of vanadium losses without application coke and natural gas with use of any coals and carbon-bearing wastes. LP-process consists of three aggregates and corresponding processes: process of liquid-phase reduction, process of vanadium-bearing pellets metallization in the shaft furnace, and process of alloying steel melting in the arc electric furnace. The obtained results have shown, that the LP-process is more energy saving on a comparison with other methods of vanadium allowing steel production. (Original)

  15. 76 FR 78888 - Final Results of Expedited Sunset Review: Ferrovanadium and Nitrided Vanadium From Russia

    Science.gov (United States)

    2011-12-20

    ... Sunset Review: Ferrovanadium and Nitrided Vanadium From Russia AGENCY: Import Administration... and nitrided vanadium from the Russian Federation (Russia), pursuant to section 751(c) of the Tariff... vanadium from Russia, pursuant to section 751(c) of the Act. See Initiation of Five-Year (``Sunset...

  16. Annealing of radiation-induced defects in vanadium and vanadium-titanium alloys

    International Nuclear Information System (INIS)

    Leguey, T.

    1996-01-01

    The annealing of defects induced by electron irradiation up to a dose of 6.10 21 m -2 at T<293 K has been investigated in single-crystals of pure vanadium and in vanadium-titanium alloys with compositions 0.3, 1 and 5 at.% Ti using positron annihilation spectroscopy. The recovery of the positron annihilation parameters in V single-crystals indicates that the defect annealing takes place in the temperature range 410-470 K without formation of microvoids for the present irradiation conditions. For the alloys the recovery onset is shifted to 460 K, the width of the annealing stage is gradually broadened with increasing Ti content, and microvoids are formed for annealing temperatures at the end of the recovery stage. The results show that the vacancy release from vacancy-interstitial impurity pairs and subsequent recombination with interstitial loops is the mechanism of the recovery in pure V. For V-Ti alloys, vacancy-Ti-interstitial impurity complexes and vacancy-Ti pairs appear to be the defects responsible for the positron trapping. The broadening of the recovery stage with increasing Ti content indicates that solute Ti is a very effective trap for vacancies in V. (orig.)

  17. Trimetallic oxide nanocomposites of transition metals titanium and vanadium by sol-gel technique: synthesis, characterization and electronic properties

    Science.gov (United States)

    Kumar, Amit; Mishra, Neeraj Kumar; Sachan, Komal; Ali, Md Asif; Soaham Gupta, Sachchidanand; Singh, Rajeev

    2018-04-01

    Novel titanium and vanadium based trimetallic oxide nanocomposites (TMONCs) have been synthesized using metal salts of titanium-vanadium along with three others metals viz. tin, aluminium and zinc as precursors by the sol-gel method. Aqueous ammonia and hydrazine hydrate were used as the reducing agents. The preparations of nanocomposites were monitored by observing the visual changes during each step of synthesis. The synthesized TMONCs were characterized using UV–vis, SEM, EDX, TEM and DLS. Band gap of the synthesized TMONCs ranges from 3–4.5 eV determined using tauc plot. FTIR study revealed the molecular stretching and bending peaks of corresponding M–O/M–O–M bonds thus confirming their formation. Molecular composition and particle size were determined using EDX and DLS respectively. Molecular shape, size and surface morphology have been examined by SEM and TEM.

  18. Three-dimensional Nitrogen-Doped Reduced Graphene Oxide/Carbon Nanotube Composite Catalysts for Vanadium Flow Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Shaofang [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Zhu, Chengzhou [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Song, Junhua [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Engelhard, Mark H. [Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354 USA.; Du, Dan [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Lin, Yuehe [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354 USA.

    2017-02-22

    The development of vanadium redox flow battery is limited by the sluggish kinetics of the reaction, especially the cathodic VO2+/VO2+ redox couples. Therefore, it is vital to develop new electrocatalyst with enhanced activity to improve the battery performance. Herein, we first synthesized the hydrogel precursor by a facile hydrothermal method. After the following carbonization, nitrogen-doped reduced graphene oxide/carbon nanotube composite was obtained. By virtue of the large surface area and good conductivey, which are ensured by the unique hybrid structure, as well as the proper nitrogen doping, the as-prepared composite presents enhanced catalytic performance toward the VO2+/VO2+ redox reaction. We also demonstrated the composite with carbon nanotube loading of 2 mg/mL exhibits the highest activity and remarkable stability in aqueous solution due to the strong synergy between reduced graphene oxide and carbon nanotubes, indicating that this composite might show promising applications in vanadium redox flow battery.

  19. 3D-printed conductive static mixers enable all-vanadium redox flow battery using slurry electrodes

    Science.gov (United States)

    Percin, Korcan; Rommerskirchen, Alexandra; Sengpiel, Robert; Gendel, Youri; Wessling, Matthias

    2018-03-01

    State-of-the-art all-vanadium redox flow batteries employ porous carbonaceous materials as electrodes. The battery cells possess non-scalable fixed electrodes inserted into a cell stack. In contrast, a conductive particle network dispersed in the electrolyte, known as slurry electrode, may be beneficial for a scalable redox flow battery. In this work, slurry electrodes are successfully introduced to an all-vanadium redox flow battery. Activated carbon and graphite powder particles are dispersed up to 20 wt% in the vanadium electrolyte and charge-discharge behavior is inspected via polarization studies. Graphite powder slurry is superior over activated carbon with a polarization behavior closer to the standard graphite felt electrodes. 3D-printed conductive static mixers introduced to the slurry channel improve the charge transfer via intensified slurry mixing and increased surface area. Consequently, a significant increase in the coulombic efficiency up to 95% and energy efficiency up to 65% is obtained. Our results show that slurry electrodes supported by conductive static mixers can be competitive to state-of-the-art electrodes yielding an additional degree of freedom in battery design. Research into carbon properties (particle size, internal surface area, pore size distribution) tailored to the electrolyte system and optimization of the mixer geometry may yield even better battery properties.

  20. Multi-layered silicides coating for vanadium alloys for generation IV reactors

    International Nuclear Information System (INIS)

    Mathieu, S.; Chaia, N.; Vilasi, M.; Le Flem, M.

    2012-01-01

    The halide-activated pack-cementation technique was employed to fabricate a diffusion coating that is resistant both to isothermal and to cyclic oxidation in air at 650 degrees C on the surface of the V-4Cr-4Ti vanadium alloy that is a potential core component of future nuclear systems. A thermodynamic assessment determined the deposit conditions in terms of master alloy, activator, filler and temperature. The partial pressures of the main gaseous species (SiCl 4 , SiCl 2 and VCl 2 ) in the pack were calculated with the master alloy Si and the mixture VSi 2 + Si. The VSi 2 + Si master alloy was used to limit vanadium loss from the surface. The obtained coating consisted of multi-layered V x Si y silicides with an outer layer of VSi 2 . This silicide developed a protective layer of silica at 650 degrees C in air and was not susceptible to the pest phenomenon, unlike other refractory silicides (MoSi 2 , NbSi 2 ). We suggest that VSi 2 exhibits no risk of rapid degradation in the gas fast reactor (GFR) conditions. (authors)

  1. In-situ investigation of hydrogen evolution behavior in vanadium redox flow batteries

    International Nuclear Information System (INIS)

    Wei, L.; Zhao, T.S.; Xu, Q.; Zhou, X.L.; Zhang, Z.H.

    2017-01-01

    Highlights: • An in-situ method to investigate hydrogen evolution in VRFBs is developed. • The rate of hydrogen evolution during battery operation is quantified. • The gas evolution behaviors in the charge process of VRFBs are observed. - Abstract: In this work, we conceived and fabricated a three-electrode electrochemical cell and transparent vanadium redox flow battery to in-situ investigate the hydrogen evolution reaction during battery operation. Experimental results show that operating temperature has a strong influence on the HER rate. In particular, compared with V"3"+ reduction reaction, HER is more sensitive to temperature variation. It is also found that, contrary to the conventional wisdom that side reactions occur at the late stage of the charge process, H_2 evolves at a relatively low SOC. About 0.26 and 1.94 mL H_2 were collected at an early (SOC lower than 20%) and end of the charge process, respectively, suggesting that attention to the hydrogen formation at the negative electrode in the early charge process should also be paid to during long-term battery operations. Moreover, the produced hydrogen gas at the negative side prefers to form macroscopically observable bubbles onto the electrode surface, covering the active sites for vanadium redox reactions, while oxygen evolution (including CO_2 production) at the positive side corrodes electrode surface and introduces certain oxygen-containing functional groups.

  2. Liquid structure of vanadium tetrachloride from neutron diffraction study

    International Nuclear Information System (INIS)

    Gopala Rao, R.V.; Satpathy, B.M.

    1982-01-01

    Assuming the separation of the intermolecular scattering function into the radial and angular parts and using Egelstaff et al's orientational model for tetrachlorides, the structure of liquid vanadium tetrachloride has been studied. It has been observed that such a separation is approximate for this liquid and the introduction of a third correction term is required to account for the molecular structure function. The chlorine-chlorine partial structure and effective angle-averaged intermolecular chlorine-chlorine potential in the liquid has been evaluated. Without taking the third correction term, introduced to generate theoretically the molecular structure function, the centre structure function has been obtained in an approximate way from the experimentally observed molecular structure function and from it the centre radial distribution function, centre direct correlation function and the angle-averaged vanadium-vanadium effective potential has been evaluated. (author)

  3. Vanadium and heat treatments effect on elastic characteristics of niobium

    International Nuclear Information System (INIS)

    Vasil'eva, E.V.; Tret'yakov, V.I.; Prokoshkin, D.A.; Pustovalov, V.A.

    1975-01-01

    The effect of vanadium content and of heat treatment conditions on the elastic properties of niobium at temperatures of 20 to 800 deg C was studied. Nb-V alloys were produced by binary vacuum remelting. The Nb-V alloys have been then subjected to thermal treatment. The total degree of deformation amounts to about 95%. The specimens were tested with a view to determine their microhardness, specific electric resistance, elasticity limit and modulus of elasticity. The elastic limit of niobium rises when alloyed with vanadium. With the increase of vanadium content the elastic limit of the alloy becomes greater. Pre-crystallization annealing at 600 - 700 deg C considerably increases the elastic limit, which is explained by development of the thermally activated processes leading to a decrease of dislocation mobility and thereby to a strengthening of the alloy

  4. The determination of vanadium in brines by atomic absorption spectroscopy

    Science.gov (United States)

    Crump-Wiesner, Hans J.; Feltz, H.R.; Purdy, W.C.

    1971-01-01

    A standard addition method is described for the determination of vanadium in brines by atomic absorption spectroscopy with a nitrous oxide-acetylene flame. Sample pH is adjusted to 1.0 with concentrated hydrochloric acid and the vanadium is directly extracted with 5% cupferron in methyl isobutyl ketone (MIBK). The ketone layer is then aspirated into the flame and the recorded absorption values are plotted as a function of the concentration of the added metal. As little as 2.5 ??g l-1 of vanadium can be detected under the conditions of the procedure. Tungsten and tin interfere when present in excess of 5 and 10 ??g ml-1, respectively. The concentrations of the two interfering ions normally found in brines are well below interference levels. ?? 1971.

  5. Oxidation of vanadium carbide in air; Oxidacion de carburo de vanadio en aire

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, A.; Troiani, L.; Materan, E. [Universidad Simon Bolivar, Depto. de la Ciencia de los Materiales, Grupo de Ingenieria de Superficies e Interfaces, Caracas, Venezuela, (Venezuela)

    1998-12-31

    It was studied the samples oxidation of vanadium carbide (V{sub 8}C{sub 7}), synterized and in powder, in order to know the temperature influence and the aggregation state in the kinetics and the oxidation products. The assays were realized in static air, at temperature between 600 y 750 Centigrade, between 6 and 24 hours periods. The gaseous products were analyzed through gas chromatography while the condensates ones were analyzed through optical microscopy and scanning electron microscopy, X-ray diffraction and chemical analysis by X-ray fluorescence analysis. It was found that in the V{sub 8}C{sub 7} oxidation occurs two basic processes: the gaseous oxides production which results of the carbon oxidation, fundamentally CO{sub 2}, and the vanadium condensate oxides production, fundamentally V{sub 2}O{sub 5}. In the synterized samples assayed under 650 Centigrade, the kinetics is lineal with loss of mass, suggesting a control by the formation of gaseous products in the sample surface, while in the synterized samples assayed over 650 Centigrade, it occurs a neat gain of mass, which is attributed to vanadium pentoxide fusion. These processes produce stratified layers of V{sub 2}O{sub 5} although at higher temperatures also it was detected V{sub 2}O{sub 4}. The superficial area effect is revealed in what the powder samples always experiment a mass neat increase in all essay temperatures, being the condensate oxidation products, fundamentally V{sub 2}O{sub 5} and V{sub 6}O{sub 13}. (Author)

  6. Fragility–structure–conductivity relations in vanadium tellurite glass

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Yue, Yuanzheng; Rodrigues, Ana Candida Martins

    the ability to intercalate lithium-ions, it is a candidate as cathode material. Here, we investigate the correlation between liquid fragility, structure and electronic conductivity in a series of vanadium-tellurite glasses with varying vanadium concentration. We measure dynamic and thermodynamic fragility...... the number of bonding and non-bonding oxygen atoms per network former, while we use IS and ESR to determine the electronic conductivity and the valence states of the system. We correlate the changes in local atomic structures as determined by NMR to the observed changes in macroscopic properties. Since...

  7. Determination of vanadium in high grade carbons by radioanalytical methods

    International Nuclear Information System (INIS)

    Jinno, K.; Sato, M.; Amemiya, S.; Katoh, T.

    1980-01-01

    The present work deals with the determination of vanadium in high grade carbons by three radioanalytical methods, viz. thermal neutron activation analysis with an accelerator, thermal neutron activation analysis with a reactor and proton induced X-ray emission analysis with an accelerator. It is shown that thermal neutron activation with an accelerator is more convenient for the rapid and non-destructive analysis of ppm-level vanadium in bulk carbons than thermal neutron activation analysis with a reactor. Proton-induced X-ray emission is less useful for the analysis of bulk samples. (author)

  8. Fluorine doped vanadium dioxide thin films for smart windows

    International Nuclear Information System (INIS)

    Kiri, Pragna; Warwick, Michael E.A.; Ridley, Ian; Binions, Russell

    2011-01-01

    Thermochromic fluorine doped thin films of vanadium dioxide were deposited from the aerosol assisted chemical vapour deposition reaction of vanadyl acetylacetonate, ethanol and trifluoroacetic acid on glass substrates. The films were characterised with scanning electron microscopy, variable temperature Raman spectroscopy and variable temperature UV/Vis spectroscopy. The incorporation of fluorine in the films led to an increase in the visible transmittance of the films whilst retaining the thermochromic properties. This approach shows promise for improving the aesthetic properties of vanadium dioxide thin films.

  9. Vanadium Doped Tungsten Oxide Material - Electrical Physical and Sensing Properties

    Directory of Open Access Journals (Sweden)

    Shishkin N. Y.

    2008-05-01

    Full Text Available The electrical physical and sensing (to VOCs and inorganic gases properties of vanadium doped tungsten oxide in the regions of phase transition temperature were investigated. Vanadium oxide (II dimerization was observed in the doped material, corresponding to new phase transition. The extreme sensitivity and selectivity to chemically active gases and vapors in small concentrations: CO, NOx, NH3 acetone, ethanol near phase transitions temperature was found. Sensor elements were manufactured for the quantitative detection (close to 1 ppm of alcohol and ammonia.

  10. Vanadium(IV)-stimulated hydrolysis of 2,3-diphosphoglycerate.

    Science.gov (United States)

    Stankiewicz, P J

    1989-05-01

    Vanadium(IV) stimulates the hydrolysis of 2,3-diphosphoglycerate at 23 degrees C. The pH optimum is 5.0. Reactions were analyzed by enzymatic and phosphate release assays. The products of 2,3-diphosphoglycerate hydrolysis are inorganic phosphate and 3-phosphoglycerate. The reaction is inhibited by high concentrations of 2,3-diphosphoglycerate and an equation has been formulated that describes the kinetic constants for this reaction at pH 7. The possible relevance of the reaction to the therapeutic lowering by vanadium(IV) of red cell 2,3-diphosphoglycerate in sickle-cell disease is discussed.

  11. EFFECT OF VANADIUM ON THE DEACTIVATION OF FCC CATALYSTS

    Directory of Open Access Journals (Sweden)

    Roncolatto R.E

    1998-01-01

    Full Text Available This work provides concrete evidence that vanadium causes the destruction of the zeolite in the FCC catalysts by a mechanism of acid attack or solid-solid transformation, as well as additional dealumination of the zeolite framework in the presence of steam and at high temperature. While these effects resulted in the reduction in crystallinity (zeolite Y content, specific area and unit cell size of the Y zeolite as the amount of vanadium in the catalysts increased, the reduction in activity was the most pronounced. The differences in these behaviors were interpreted and the model can be used for better catalyst formulation or screening.

  12. Calculations of oscillation spectra of disordered interstitial solid solutions of vanadium-oxygen system

    International Nuclear Information System (INIS)

    Danilkin, S.A.

    1978-01-01

    The frequency spectra calculation of disordered solid interstitial solutions of a vanadium-oxygen system for oxygen concentration of 5.9% and 15.8% (V 16 O and V 16 O 3 ) is carried out. The axially-symmetric model of crystal lattice dinamics with consideration of vanadium-oxygen and vanadium-vanadium interactions up to the second coordination sphere is used. On the whole, the obtained spectra are in qualitative agreement with experiment and reflect correctly all the changes in frequency spectra of pure vanadium on doping with oxygen

  13. Ion-exchange preparation of high-purity vanadium acid from industrial liquors

    International Nuclear Information System (INIS)

    Sajdakhmedov, U.A.; Arslanov, Sh.S.; Vulikh, A.I.

    1994-01-01

    The results of investigations on production of special-purity vanadium acid and vanadium oxide directly from process solutions (technical grade liquors) using ionites are presented. Potentiality of thorough purification of vanadium(5) oxide, when producing vanadium acid on the KU-2 cationite with subsequent purification on anionite, is shown. On the basis of the results obtained a principle flowsheet of ion-exchange production of high-purity vanadium(5) oxide from industrial liquors has been developed. 2 refs.; 1 fig.; 4 tabs

  14. Fast-neutron elastic scattering from elemental vanadium

    International Nuclear Information System (INIS)

    Smith, A.B.; Guenther, P.T.; Lawson, R.D.

    1988-03-01

    Differential neutron elastic- and inelastic-scattering cross sections of vanadium were measured from 4.5 to 10 MeV. These results were combined with previous 1.5 to 4.0 MeV data from this laboratory, the 11.1 MeV elastic-scattering results obtained at Ohio University, and the reported neutron total cross sections to energies of ∼20.0 MeV, to form a data base which was interpreted in terms of the spherical optical-statistical model. A fit to the data was achieved by making both the strengths and geometries of the optical-model potential energy dependent. This energy dependence was large below ∼6.0 MeV. Above ∼6.0 MeV the energy dependencies are smaller, and similar to those characteristic of global models. Using the dispersion relationship and the method of moments, the optical-model potential energy deduced from 0.0 to 11.1 MeV neutron-scattering data was extrapolated to higher energies and to the bound-state regime. This extrapolation leads to predicted neutron total cross sections that are within 3% of the experimental values throughout the energy range 0.0 to 20.0 MeV. Furthermore, the values of the volume-integral-per-nucleon of the real potential are in excellent agreement with those needed to reproduce the observed binding energies of particle- and hole-states. The latter gives clear evidence of the Fermi surface anomaly. Using only the 0.0 to 11.1 MeV data, the predicted E < O behavior of the strength and radius of the real shell-model Woods-Saxon potential are somewhat different from those obtained by Mahaux and Sartor in their analysis of nuclei near closed shells. 61 refs., 9 figs., 2 tabs

  15. Oxidation of vanadium metal in oxygen plasma and their characterizations

    Science.gov (United States)

    Sharma, Rabindar Kumar; Singh, Megha; Kumar, Prabhat; Reddy, G. B.

    2015-09-01

    In this report, the role of oxygen plasma on oxidation of vanadium (V) metal and the volatilization of its oxides has been studied as a function of source (V metal strip) temperature (Tss) and oxygen partial pressure (PO2). The presence of O2-plasma not only enhances the oxidation rate but also ficilitates in transport of oxide molecules from metal to substrate, as confirmed by the simultanous deposition of oxide film onto substrate. Both the oxidized metal strips and oxide films deposited on substrates are characterized separately. The structural and vibrational results evidence the presence of two different oxide phases (i.e. orthorhombic V2O5 and monocilinic V O2) in oxide layers formed on V metal strips, whereas the oxide films deposited on substrates exhibit only orthorhombic phase (i.e. V2O5). The decrease in peak intensities recorded from heated V metal strips on increasing Tss points out the increment in the rate of oxide volatilization, which also confirms by the oxide layer thickness measurements. The SEM results show the noticeable surface changes on V-strips as the function of Tss and PO2 and their optimum values are recorded to be 500 ˚ C and 7.5 × 10-2 Torr, respectively to deposit maximum thick oxide film on substrate. The formation of microcracks on oxidized V-strips, those responsible to countinue oxidation is also confirmed by SEM results. The compositional study of oxide layers formed on V-strips, corroborates their pureness and further assures about the existence of mixed oxide phases. The effect of oxygen partial pressure on oxidation of V-metal has also been discussed in the present report. All the results are well in agreement to each other.

  16. Optimal Location of Vanadium in Muscovite and Its Geometrical and Electronic Properties by DFT Calculation

    Directory of Open Access Journals (Sweden)

    Qiushi Zheng

    2017-02-01

    Full Text Available Vanadium-bearing muscovite is the most valuable component of stone coal, which is a unique source of vanadium manufacture in China. Numbers of experimental studies have been carried out to destroy the carrier muscovite’s structure for efficient extraction of vanadium. Hence, the vanadium location is necessary for exploring the essence of vanadium extraction. Although most infer that vanadium may substitute for trivalent aluminium (Al as the isomorphism in muscovite for the similar atomic radius, there is not enough experimental evidence and theoretical supports to accurately locate the vanadium site in muscovite. In this study, the muscovite model and optimal location of vanadium were calculated by density functional theory (DFT. We find that the vanadium prefers to substitute for the hexa-coordinated aluminum of muscovite for less deformation and lower substitution energy. Furthermore, the local geometry and relative electronic properties were calculated in detail. The basal theoretical research of muscovite contained with vanadium are reported for the first time. It will make a further influence on the technology development of vanadium extraction from stone coal.

  17. Vanadium Recovery from Oil Fly Ash by Carbon Removal and Roast-Leach Process

    Science.gov (United States)

    Jung, Myungwon; Mishra, Brajendra

    2018-02-01

    This research mainly focuses on the recovery of vanadium from oil fly ash by carbon removal and the roast-leach process. The oil fly ash contained about 85% unburned carbon and 2.2% vanadium by weight. A vanadium-enriched product was obtained after carbon removal, and the vanadium content of this product was 19% by weight. Next, the vanadium-enriched product was roasted with sodium carbonate to convert vanadium oxides to water-soluble sodium metavanadate. The roasted sample was leached with water at 60°C, and the extraction percentage of vanadium was about 92% by weight. Several analytical techniques, such as inductively coupled plasma atomic emission spectroscopy (ICP-AES), x-ray fluorescence (XRF), and thermogravimetric and differential thermal analysis (TG-DTA), were utilized for sample analyses. Thermodynamic modeling was also conducted with HSC chemistry software to explain the experimental results.

  18. Local structure of vanadium in doped LiFePO4

    International Nuclear Information System (INIS)

    Zhao, Ting; Xu, Wei; Ye, Qing; Cheng, Jie; Zhao, Haifeng; Chu, Wangsheng; Wu, Ziyu; Univ. of Science and Technology of China, Hefei; Xia, Dingguo

    2010-01-01

    LiFePO 4 composites with 5 at.% vanadium doping are prepared by solid state reactions. X-ray absorption fine-structure spectroscopy is used as a novel technique to identify vanadium sites. Both experimental analyses and theoretical simulations show that vanadium does not enter into the LiFePO 4 crystal lattice. When the vanadium concentration is lower then 1 at.%, the dopant remains insoluble. Thus, a single-phase vanadium-doped LiFePO4 cannot be formed and the improved electrochemical properties of vanadium doped LiFePO 4 previously reported cannot be associated with crystal structure changes of the LiFePO 4 via vanadium doping. (orig.)

  19. Two-stage fungal leaching of vanadium from uranium ore residue of the leaching stage using statistical experimental design

    International Nuclear Information System (INIS)

    Gharehbagheri, Hassan; Safdari, Jaber; Roostaazad, Reza; Rashidi, Abbas

    2013-01-01

    Highlights: ► In this work, the percent of vanadium recovery from uranium mine waste was 44.8. ► Unlike autotrophs, Aspergillus niger is a suitable microorganism to deal with such a resource. ► In the first step of the present work, citric acid was produced more than the other acids. ► When sterilization of uranium ore waste is not economic, two-step bioleaching is an appropriate method. - Abstract: In this investigation, bioleaching of vanadium from uranium ore residue of the leaching stage was studied by Aspergillus niger in a two-step process at 30 °C and 150 rpm. The first step was initiated by growth of fungi in the absence of mine waste. Using response surface methodology, three factors were surveyed for fungal growth: initial pH, sucrose concentration and spore population. Also concentrations of oxalic, citric, and gluconic acids were measured as response in this step. During 30 days, maximum productions of these acids were 3265, 11578, and 7988 mg/l, respectively. Initial pH and sucrose concentration were significant factors for oxalic and citric acid production; however, for gluconic acid production sucrose concentration and spore population were significant. Then, the content of each flask was filtered and mine waste was added to liquor with pulp density of 3%. During 3 days, in the second step, vanadium recovered about 44.8% in the liquor

  20. Compatibility of vanadium alloys with reactor-grade helium for fusion reactor applications

    International Nuclear Information System (INIS)

    Bell, G.E.C.; Bishop, P.S.

    1993-01-01

    Tests were conducted to determine the compatibility of vanadium alloys with reactor-grade helium and to define the helium gas chemistry requirements for fusion reactors, miniature tensile specimens of V-5Cr-5Ti. V-10Cr-5Ti, and V-12.5Cr-5 Ti were exposed in a once-through system to helium with 70 vppm-H 2 (measured oxygen partial pressures of 10 -12 atm) and bottle helium (measured oxygen partial pressures of -4 atm) between 500 and 700 degree C for up to 1008 h. The weight changes in the specimens were recorded. The helium-exposed specimens were tensile tested, and the effects of exposure on mechanical properties were assessed. Exposure between 500 and 700 degree C for 1008 h in He+70 vppm-H 2 resulted in complete embrittlement of all the alloys in room temperature tensile tests. The fracture mode was primarily cleavage, probably caused by a hydrogen-induced shift in the ductile to brittle transition temperature (DBTT). Weight gains increased with temperature and were largest for the V-5Cr-5Ti alloy. Specimens exposed for 531 h between 500 and 700 degree C in bottle He exhibited two distinct fracture morphologies on the fracture surfaces. Brittle cleavage around the edges of specimens gave way to ductile dimpling in the center of the specimens. The brittle region around the periphery of the specimen is most likely the highest vanadium oxide. V 2 O 5

  1. Vanadium oxide nanowire-carbon nanotube binder-free flexible electrodes for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Perera, Sanjaya D.; Patel, Bijal; Seitz, Oliver; Ferraris, John P.; Balkus, Kenneth J. Jr. [Department of Chemistry and the Alan G. MacDiarmid Nanotech Institute, 800 West Campbell Rd, University of Texas at Dallas, Richardson, TX 75080 (United States); Nijem, Nour; Roodenko, Katy; Chabal, Yves J. [Laboratory for Surface and Nanostructure Modification, Department of Material Science and Engineering, 800 West Campbell Rd, University of Texas Dallas, Richardson, TX 75080 (United States)

    2011-10-15

    Vanadium pentoxide (V{sub 2}O{sub 5}) layered nanostructures are known to have very stable crystal structures and high faradaic activity. The low electronic conductivity of V{sub 2}O{sub 5} greatly limits the application of vanadium oxide as electrode materials and requires combining with conducting materials using binders. It is well known that the organic binders can degrade the overall performance of electrode materials and need carefully controlled compositions. In this study, we develop a simple method for preparing freestanding carbon nanotube (CNT)-V{sub 2}O{sub 5} nanowire (VNW) composite paper electrodes without using binders. Coin cell type (CR2032) supercapacitors are assembled using the nanocomposite paper electrode as the anode and high surface area carbon fiber electrode (Spectracarb 2225) as the cathode. The supercapacitor with CNT-VNW composite paper electrode exhibits a power density of 5.26 kW Kg{sup -1} and an energy density of 46.3 Wh Kg{sup -1}. (Li)VNWs and CNT composite paper electrodes can be fabricated in similar manner and show improved overall performance with a power density of 8.32 kW Kg{sup -1} and an energy density of 65.9 Wh Kg{sup -1}. The power and energy density values suggest that such flexible hybrid nanocomposite paper electrodes may be useful for high performance electrochemical supercapacitors. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Water-activated graphite felt as a high-performance electrode for vanadium redox flow batteries

    Science.gov (United States)

    Kabtamu, Daniel Manaye; Chen, Jian-Yu; Chang, Yu-Chung; Wang, Chen-Hao

    2017-02-01

    A simple, green, novel, time-efficient, and potentially cost-effective water activation method was employed to enhance the electrochemical activity of graphite felt (GF) electrodes for vanadium redox flow batteries (VRFBs). The GF electrode prepared with a water vapor injection time of 5 min at 700 °C exhibits the highest electrochemical activity for the VO2+/VO2+ couple among all the tested electrodes. This is attributed to the small, controlled amount of water vapor that was introduced producing high contents of oxygen-containing functional groups, such as sbnd OH groups, on the surface of the GF fibers, which are known to be electrochemically active sites for vanadium redox reactions. Charge-discharge tests further confirm that only 5 min of GF water activation is required to improve the efficiency of the VRFB cell. The average coulombic efficiency, voltage efficiency, and energy efficiency are 95.06%, 87.42%, and 83.10%, respectively, at a current density of 50 mA cm-2. These voltage and energy efficiencies are determined to be considerably higher than those of VRFB cells assembled using heat-treated GF electrodes without water activation and pristine GF electrodes.

  3. Ab initio Investigation of Helium in Vanadium Oxide Nanoclusters

    Science.gov (United States)

    Danielson, Thomas; Tea, Eric; Hin, Celine

    Nanostructured ferritic alloys (NFAs) are strong candidate materials for the next generation of fission reactors and future fusion reactors. They are characterized by a large number density of oxide nanoclusters dispersed throughout a BCC iron matrix, where current oxide nanoclusters are primarily comprised of Y-Ti-O compounds. The oxide nanoclusters provide the alloy with high resistance to neutron irradiation, high yield strength and high creep strength at the elevated temperatures of a reactor environment. In addition, the oxide nanoclusters serve as trapping sites for transmutation product helium providing substantially increased resistance to catastrophic cracking and embrittlement. Although the mechanical properties and radiation resistance of the existing NFAs is promising, the problem of forming large scale reactor components continues to present a formidable challenge due to the high hardness and unpredictable fracture behavior of the alloys. An alternative alloy has been previously proposed and fabricated where vanadium is added in order to form vanadium oxide nanoclusters that serve as deflection sites for crack propagation. Although experiments have shown evidence that the fracture behavior of the alloys is improved, it is unknown whether or not the vanadium oxide nanoclusters are effective trapping sites for helium. We present results obtained using density functional theory investigating the thermodynamic stability of helium with the vanadium oxide matrix to make a comparison of trapping effectiveness to traditional Y-Ti-O compounds.

  4. Vanadium Effect on a Medium Carbon Forging Steel

    Directory of Open Access Journals (Sweden)

    Carlos Garcia-Mateo

    2016-05-01

    Full Text Available In the present work the influence of vanadium on the hardenability and the bainitic transformation of a medium carbon steel is analyzed. While V in solid solution enhances the former, it hardly affects bainitic transformation. The results also reveal an unexpected result, an increase of the prior austenite grain size as the V content increases.

  5. Vanadium, rubidium and potassium in Octopus vulgaris (Mollusca: Cephalopoda

    Directory of Open Access Journals (Sweden)

    Sónia Seixas

    2005-06-01

    Full Text Available The levels of vanadium, rubidium and potassium were determined in Octopus vulgaris caught during commercial fishing activities at three locations (Cascais, Santa Luzia and Viana do Castelo in Portugal in autumn and spring. We determined the concentration of these elements in digestive gland, branchial heart, gills, mantle and arms in males and females. At least five males and five females were assessed for each season/location combination. Elemental concentrations were determined by Particle Induced X-ray Emission (PIXE. Vanadium was detectable only in digestive gland and branchial heart samples. Its concentration was not correlated with total weight, total length or mantle length. There were no differences in concentrations of V, Rb and K between sexes. There were significant differences in vanadium concentrations in branchial hearts in autumn between samples from Viana do Castelo and those from the other two sites. We found a significant positive relationship between the concentration of vanadium and those of potassium and rubidium in branchial hearts. Branchial hearts appear to play an important role in decontamination of V.

  6. Vanadium based materials as electrode materials for high performance supercapacitors

    Science.gov (United States)

    Yan, Yan; Li, Bing; Guo, Wei; Pang, Huan; Xue, Huaiguo

    2016-10-01

    As a kind of supercapacitors, pseudocapacitors have attracted wide attention in recent years. The capacitance of the electrochemical capacitors based on pseudocapacitance arises mainly from redox reactions between electrolytes and active materials. These materials usually have several oxidation states for oxidation and reduction. Many research teams have focused on the development of an alternative material for electrochemical capacitors. Many transition metal oxides have been shown to be suitable as electrode materials of electrochemical capacitors. Among them, vanadium based materials are being developed for this purpose. Vanadium based materials are known as one of the best active materials for high power/energy density electrochemical capacitors due to its outstanding specific capacitance and long cycle life, high conductivity and good electrochemical reversibility. There are different kinds of synthetic methods such as sol-gel hydrothermal/solvothermal method, template method, electrospinning method, atomic layer deposition, and electrodeposition method that have been successfully applied to prepare vanadium based electrode materials. In our review, we give an overall summary and evaluation of the recent progress in the research of vanadium based materials for electrochemical capacitors that include synthesis methods, the electrochemical performances of the electrode materials and the devices.

  7. Solubility of nitrogen in iron alloys with vanadium and niobium

    International Nuclear Information System (INIS)

    Pomarin, Yu.M.; Grigorenko, G.M.; Lakomskij, V.I.

    1975-01-01

    The solubility of nitrogen in the concentration range under study in Fe-N-V and Fe-N-Nb systems is in compliance with Syverts' law. An equation has been set up so as to estimate the nitrogen solubility in the iron alloys containing up to 10 per cent of vanadium and niobium in the wide temperature range

  8. Effects of Vanadium Pentoxide on the Histological and Sperm ...

    African Journals Online (AJOL)

    The pharmacological effects of intraperitoneal administration of different doses of vanadium pentoxide (V2O5) on the histological and sperm parameters of male guinea pigs were investigated. Also investigated were the effects of oral pretreatment with different doses of vitamin E (a known protein kinase C inhibitor) on the ...

  9. Novel hybrid materials based on the vanadium oxide nanobelts

    Energy Technology Data Exchange (ETDEWEB)

    Zabrodina, G.S., E-mail: kudgs@mail.ru [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation); Makarov, S.G.; Kremlev, K.V. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation); Yunin, P.A.; Gusev, S.A. [Institute for Physics of Microstructures Russian Academy of Sciences, Nizhny Novgorod 603087 (Russian Federation); Kaverin, B.S.; Kaverina, L.B. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Ketkov, S.Yu. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation)

    2016-04-15

    Graphical abstract: - Highlights: • Flat and curved vanadium oxide nanobelts have been synthesized. • Hybrid material was prepared via decoration of flexible nanobelts with zinc phthalocyanine. • Investigations of the thermal stability, morphologies and structures were carried out. - Abstract: Novel hybrid materials based on zinc phthalocyanine and nanostructured vanadium oxides have attracted extensive attention for the development of academic research and innovative industrial applications such as flexible electronics, optical sensors and heterogeneous catalysts. Vanadium oxides nanobelts were synthesized via a hydrothermal treatment V{sub 2}O{sub 5}·nH{sub 2}O gel with surfactants (TBAB, CTAB) used as structure-directing agents, where CTAB – cetyltrimethylammonium bromide, TBAB – tetrabutylammonium bromide. Hybrid materials were prepared decoration of (CTA){sub 0.33}V{sub 2}O{sub 5} flexible nanobelts with cationic zinc phthalocyanine by the ion-exchange route. Investigations of the thermal stability, morphologies and structures of the (CTA){sub 0.33}V{sub 2}O{sub 5}, (TBA){sub 0.16}V{sub 2}O{sub 5} nanobelts and zinc phthalocyanine exchange product were carried out. The hybrid materials based on the nanostructured vanadium oxide and zinc phthalocyanine were tested as photocatalysts for oxidation of citronellol and 2-mercaptoethanol by dioxygen.

  10. Experimental study on the alluminothermic reduction of vanadium pentoxide

    International Nuclear Information System (INIS)

    Mourao, M.B.; Capocchi, J.D.T.

    1982-01-01

    The investigation on the alluminothermic reduction of V 2 O 5 carried out in open refractory lined reaction vessels, is reported. The effects of process variables such as particle size of the reactants, size of the charge, excess of alluminium, flux addition to the reacting mixture and the ignition method are considered, regarding the metallic recovery of vanadium. (Author) [pt

  11. Combined effect of vanadium and nickel on lipid peroxidation and ...

    African Journals Online (AJOL)

    use

    2011-12-12

    Dec 12, 2011 ... to nickel led to a significant decrease (p < 0.001) in SOD, GST activities in liver and GSH content in ..... administration and GSH is oxidized to disulfide form .... Chasteen N (1983). The biochemistry of vanadium. Struct. Bond.

  12. Singlet oxygenation in microemulsion catalysed by vanadium chloroperoxidase

    NARCIS (Netherlands)

    Renirie, R.; Pierlot, C.; Wever, R.; Aubry, J.-M.

    2009-01-01

    Non-ionic microemulsions compatible with the enzyme vanadium chloroperoxidase were designed to perform singlet oxygenation of apolar substrates. The media were based on mono- and polydisperse ethoxylated fatty alcohols (CiEj). octane and aqueous buffer. "Fish" diagrams were determined to identify

  13. Annealing of neutron-irradiated vanadium containing oxygen

    International Nuclear Information System (INIS)

    Foster, R.E.

    1979-01-01

    A study to clarify the role of interstitial oxygen in irradiated vanadium by measuring the activation energy of the 0.2 T/sub m/ recovery stage in well-characterized samples, where T/sub m/ is the melting temperature in degrees Kelvin, is described

  14. Anisotropic Born-Mayer potential in lattice dynamics of Vanadium

    International Nuclear Information System (INIS)

    Onwuagba, B.N.

    1988-01-01

    A microscopic theory of the lattice dynamics of the transition metal vanadium is developed based on the Animalu's transition metal model potential (TMMP). The Born-Mayer potential associated with the distribution of the transition metal d-electrons is treated as anisotropic. Good agreement with experimental phonon dispersion curves longitudinal branches in the [111] direction

  15. Speciation of Chromium and Vanadium in Medicinal Plants

    African Journals Online (AJOL)

    NICOLAAS

    lamps of vanadium and chromium operating at 318.4 nm and. 357.9 nm have .... Table 1 Results for the determination of Cr and V in soil (n = 6). [Cr(VI)]. Total [Cr] .... hydrogen storage: Attributes for near-term, early market PEM fuel cells, Curr.

  16. Medium carbon vanadium steels for closed die forging

    International Nuclear Information System (INIS)

    Jeszensky, Gabor; Plaut, Ronald Lesley

    1993-01-01

    This work analyses the medium carbon micro alloyed vanadium potential for closed die forged production. The steels reach the mechanical resistance requests during cooling after forging, eliminating the subsequent thermal treatment. Those steels also present good fatigue resistance and machinability. The industrial scale experiments are also reported

  17. Preparation Of Pure Vanadium Pentoxide From Red Cake

    International Nuclear Information System (INIS)

    ZAREH, M.M.; EL-HAZEK, M.N; BU ZAID, A.H.M; MOHAMED, H.S.

    2010-01-01

    The red cake, extracted from petroleum ash by acid leaching, contains some impurities such as iron, nickel, zinc, Cr and Cu. For purification the red cake, vanadium in the red cake was taken into solution by treating the red cake with soda ash solution at 90 o C, S /L 1/10 and leaching time of 6 h. The obtained leaching efficiency of vanadium reached 99 %. The solution was clarified by filtration and slurred with solid ammonium sulphate (50g/l) and ammonium chloride (50 g/l). The pH of the slurry was kept at 8-9 by adding ammonium hydroxide. Ammonium metavanadate was crystallized from the slurry at room temperature and during the crystallization step, the slurry was kept under mild agitation. The reaction between the sodium vanadate and ammonium sulphate led to the formation of ammonium metavanadate (AMV) 98.35 % (atomic adsorption techniques). The AMV crystals were separated from the residual liquor by filtration, washed with 5% ammonium chloride solution then dried at 100 o C. Over 98.35 % of the vanadium contained in the red cake was recovered by this way as AMV. Thermal decomposition of AMV at 350 o C 1 h yielded 99.32 % pure vanadium pentoxide.

  18. Influence of hydrogen on high cycle fatigue of polycrystalline vanadium

    International Nuclear Information System (INIS)

    Chung, D.W.; Lee, K.S.; Stoloff, N.S.

    1977-02-01

    The room temperature fatigue behavior of several polycrystalline V-H 2 alloys is described. Hydrogen extends the life of unnotched vanadium but has a deleterious effect in notched materials. Crack propagation data are correlated with tensile yield stress and cyclic strain hardening data

  19. Halofunctionalization of alkenes by vanadium chloroperoxidase from Curvularia inaequalis

    NARCIS (Netherlands)

    Dong, J.; Fernandez Fueyo, E.; Li, Jingbo; Guo, Zheng; Renirie, Rokus; Wever, Ron; Hollmann, F.

    The vanadium-dependent chloroperoxidase from Curvularia inaequalis is a stable and efficient biocatalyst for the hydroxyhalogenation of a broad range of alkenes into halohydrins. Up to 1 200 000 TON with 69 s−1 TOF were observed for the biocatalyst. A bienzymatic cascade to yield epoxides as

  20. Photocatalytic activity of TiO2 doped with boron and vanadium

    International Nuclear Information System (INIS)

    Bettinelli, M.; Dallacasa, V.; Falcomer, D.; Fornasiero, P.; Gombac, V.; Montini, T.; Romano, L.; Speghini, A.

    2007-01-01

    Boron (B)- and vanadium (V)-doped TiO 2 photocatalysts were synthesized using modified sol-gel reaction processes and characterized by X-ray diffraction (XRD), Raman spectroscopy and N 2 physisorption (BET). The photocatalytic activities were evaluated by monitoring the degradation of methylene blue (MB). The results showed that the materials possess high surface area. The addition of B favored the transformation of anatase to rutile, while in the presence of V, anatase was the only phase detected. The MB degradation on V-doped TiO 2 was significantly affected by the preparation method. In fact while the presence of V in the bulk did not influence strongly the photoreactivity under visible irradiation, an increase of surface V doping lead to improved photodegradation of MB. The degradation of MB dye indicated that the photocatalytic activities of TiO 2 increased as the boron doping increased, with high conversion efficiency for 9 mol% B doping

  1. Hydrogen evolution at the negative electrode of the all-vanadium redox flow batteries

    Science.gov (United States)

    Sun, Che-Nan; Delnick, Frank M.; Baggetto, Loïc; Veith, Gabriel M.; Zawodzinski, Thomas A.

    2014-02-01

    This work demonstrates a quantitative method to determine the hydrogen evolution rate occurring at the negative carbon electrode of the all vanadium redox flow battery (VRFB). Two carbon papers examined by buoyancy measurements yield distinct hydrogen formation rates (0.170 and 0.005 μmol min-1 g-1). The carbon papers have been characterized using electron microscopy, nitrogen gas adsorption, capacitance measurement by electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). We find that the specific electrochemical surface area (ECSA) of the carbon material has a strong influence on the hydrogen generation rate. This is discussed in light of the use of high surface area material to obtain high reaction rates in the VRFB.

  2. A high-performance dual-scale porous electrode for vanadium redox flow batteries

    Science.gov (United States)

    Zhou, X. L.; Zeng, Y. K.; Zhu, X. B.; Wei, L.; Zhao, T. S.

    2016-09-01

    In this work, we present a simple and cost-effective method to form a dual-scale porous electrode by KOH activation of the fibers of carbon papers. The large pores (∼10 μm), formed between carbon fibers, serve as the macroscopic pathways for high electrolyte flow rates, while the small pores (∼5 nm), formed on carbon fiber surfaces, act as active sites for rapid electrochemical reactions. It is shown that the Brunauer-Emmett-Teller specific surface area of the carbon paper is increased by a factor of 16 while maintaining the same hydraulic permeability as that of the original carbon paper electrode. We then apply the dual-scale electrode to a vanadium redox flow battery (VRFB) and demonstrate an energy efficiency ranging from 82% to 88% at current densities of 200-400 mA cm-2, which is record breaking as the highest performance of VRFB in the open literature.

  3. Efficient Separation and Extraction of Vanadium and Chromium in High Chromium Vanadium Slag by Selective Two-Stage Roasting-Leaching

    Science.gov (United States)

    Wen, Jing; Jiang, Tao; Xu, Yingzhe; Liu, Jiayi; Xue, Xiangxin

    2018-06-01

    Vanadium and chromium are important rare metals, leading to a focus on high chromium vanadium slag (HCVS) as a potential raw material to extract vanadium and chromium in China. In this work, a novel method based on selective two-stage roasting-leaching was proposed to separate and extract vanadium and chromium efficiently in HCVS. XRD, FT-IR, and SEM were utilized to analyze the phase evolutions and microstructure during the whole process. Calcification roasting, which can calcify vanadium selectively using thermodynamics, was carried out in the first roasting stage to transfer vanadium into acid-soluble vanadate and leave chromium in the leaching residue as (Fe0.6Cr0.4)2O3 after H2SO4 leaching. When HCVS and CaO were mixed in the molar ratio CaO/V2O3 (n(CaO)/n(V2O3)) of 0.5 to 1.25, around 90 pct vanadium and less than 1 pct chromium were extracted in the first leaching liquid, thus achieving the separation of vanadium and chromium. In the second roasting stage, sodium salt, which combines with chromium easily, was added to the first leaching residue to extract chromium and 95.16 pct chromium was extracted under the optimal conditions. The total vanadium and chromium leaching rates were above 95 pct, achieving the efficient separation and extraction of vanadium and chromium. The established method provides a new technique to separate vanadium and chromium during roasting rather than in the liquid form, which is useful for the comprehensive application of HCVS.

  4. Efficient Separation and Extraction of Vanadium and Chromium in High Chromium Vanadium Slag by Selective Two-Stage Roasting-Leaching

    Science.gov (United States)

    Wen, Jing; Jiang, Tao; Xu, Yingzhe; Liu, Jiayi; Xue, Xiangxin

    2018-04-01

    Vanadium and chromium are important rare metals, leading to a focus on high chromium vanadium slag (HCVS) as a potential raw material to extract vanadium and chromium in China. In this work, a novel method based on selective two-stage roasting-leaching was proposed to separate and extract vanadium and chromium efficiently in HCVS. XRD, FT-IR, and SEM were utilized to analyze the phase evolutions and microstructure during the whole process. Calcification roasting, which can calcify vanadium selectively using thermodynamics, was carried out in the first roasting stage to transfer vanadium into acid-soluble vanadate and leave chromium in the leaching residue as (Fe0.6Cr0.4)2O3 after H2SO4 leaching. When HCVS and CaO were mixed in the molar ratio CaO/V2O3 (n(CaO)/n(V2O3)) of 0.5 to 1.25, around 90 pct vanadium and less than 1 pct chromium were extracted in the first leaching liquid, thus achieving the separation of vanadium and chromium. In the second roasting stage, sodium salt, which combines with chromium easily, was added to the first leaching residue to extract chromium and 95.16 pct chromium was extracted under the optimal conditions. The total vanadium and chromium leaching rates were above 95 pct, achieving the efficient separation and extraction of vanadium and chromium. The established method provides a new technique to separate vanadium and chromium during roasting rather than in the liquid form, which is useful for the comprehensive application of HCVS.

  5. Creep and creep rupture properties of unalloyed vanadium and solid-solution-strengthened vanadium-base alloys

    International Nuclear Information System (INIS)

    Kainuma, T.; Iwao, N.; Suzuki, T.; Watanabe, R.

    1982-01-01

    The creep and creep rupture properties of vanadium and vanadium-base alloys were studied at 700 and 1000 0 C. The alloys were vanadium-base binary alloys containing about 5 - 21 at.% Al, Ti, Nb, Ta, Cr, Mo or Fe, three V-20wt.%Nb-base ternary alloys containing 5 or 10 wt.% Al, Cr or Mo, V-10wt.%Ta-10wt.%Al and V-25wt.%Cr-0.8wt.%Zr. The creep rupture stress of the binary alloys, except the V-Al and V-Ti alloys, increased linearly with increasing concentration of the alloying elements. The V-Nb alloy had the best properties with respect to the rupture stress and creep rate at 700 0 C and the rupture stress at 1000 0 C, but the V-Mo alloy appeared likely to have better creep properties at longer times and higher temperatures. Of the five ternary alloys, V-20wt.%Nb-5wt.%Cr and V-20wt.%Nb-10wt.%Mo showed the best creep properties. The creep properties of these two alloys were compared with those of other vanadium alloys and of type 316 stainless steel. (Auth.)

  6. A novel comprehensive utilization of vanadium slag: As gamma ray shielding material

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Mengge [School of Metallurgy, Northeastern University, Shenyang 110004 (China); Liaoning Key Laboratory of Metallurgical Resources Recycling Science, Shenyang 110004 (China); Xue, Xiangxin, E-mail: xuexx@mail.neu.edu.cn [School of Metallurgy, Northeastern University, Shenyang 110004 (China); Liaoning Key Laboratory of Metallurgical Resources Recycling Science, Shenyang 110004 (China); Yang, He; Liu, Dong [School of Metallurgy, Northeastern University, Shenyang 110004 (China); Liaoning Key Laboratory of Metallurgical Resources Recycling Science, Shenyang 110004 (China); Wang, Chao [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Zhefu [Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2016-11-15

    Highlights: • A novel comprehensive utilization method for vanadium slag is proposed. • Shielding properties of vanadium slag are better than ordinary concrete. • HVL of vanadium slag is between Lead and concrete to shield {sup 60}Co gamma ray. • HVL of composite is higher than concrete when adding amount of vanadium slag is 900. • Composite can be used as injecting mortar for cracks developed in concrete shields. - Abstract: New exploration of vanadium slag as gamma ray shielding material was proposed, the shielding properties of vanadium slag was higher than concrete when the energy of photons was in 0.0001 MeV–100000 MeV. Vanadium slag/epoxy resin composites were prepared, shielding and material properties of materials were tested by {sup 60}Co gamma ray, simultaneous DSC-TGA, electronic universal testing machine and scanning electron microscopy, respectively. The results showed that the shielding properties of composite would be better with the increase of vanadium slag addition amount. The HVL (half value layer thickness) of vanadium slag was between Lead and concrete while composite was higher than concrete when the addition amount of vanadium slag was 900 used as material to shield {sup 60}Co gamma ray, also the resistance temperature of composite was about 215 °C and the bending strength was over 10 MPa. The composites could be used as injecting mortar for cracks developed in biological concrete shields, coating for the floor of the nuclear facilities, and shielding materials by itself.

  7. The role of phosphate additive in stabilization of sulphuric-acid-based vanadium(V) electrolyte for all-vanadium redox-flow batteries

    Science.gov (United States)

    Roznyatovskaya, Nataliya V.; Roznyatovsky, Vitaly A.; Höhne, Carl-Christoph; Fühl, Matthias; Gerber, Tobias; Küttinger, Michael; Noack, Jens; Fischer, Peter; Pinkwart, Karsten; Tübke, Jens

    2017-09-01

    Catholyte in all-vanadium redox-flow battery (VRFB) which consists of vanadium salts dissolved in sulphuric acid is known to be stabilized by phosphoric acid to slow down the thermal aging at temperatures higher than 40 °C. To reveal the role of phosphoric acid, the thermally-induced aggregation is investigated using variable-temperature 51V, 31P, 17O, 1H nuclear magnetic resonance (NMR) spectroscopy and dynamic light scattering (DLS). The results indicate that the thermal stabilization of vanadium(V) electrolyte is attained by the involvement of monomeric and dimeric vanadium(V) species in the reaction with phosphoric acid which is concurrent to the formation of neutral hydroxo-aqua vanadium(V) precipitation precursor. The dimers are stabilized by counter ions due to association reaction or if such stabilization is not possible, precipitation of vanadium pentoxide is favored. The evolution of particles size distributions at 50 °C in electrolyte samples containing 1.6 M vanadium and 4.0 M total sulphate and the pathways of precipitate formation are discussed. The optimal total phosphate concentration is found to be of 0.15 M. However, the induction time is assumed to be dependent not only on the total phosphate concentrations, but also on the ratio of total vanadium(V) to sulphate concentrations.

  8. Effects of hydrogen on fatigue of vanadium and niobium. Annual report

    International Nuclear Information System (INIS)

    Stoloff, N.S.; Chung, D.W.

    1977-01-01

    The fatigue behavior of unalloyed vanadium and niobium as well as their alloys with hydrogen is described. The response of vanadium-hydrogen alloys to cyclic loading is shown to depend markedly upon the presence or absence of notches, the hydrogen level, method of test, and frequency. In general, hydrides improve high cycle life of unnotched alloys, but are detrimental in the presence of a notch. Low test frequencies also lead to reduced fatigue lives. Stress-assisted hydride growth in previously hydrided alloys has been noted both in fatigue and in delayed failure experiments. Unalloyed vanadium and solid solution vanadium-hydrogen alloys do not undergo delayed failure. Preliminary tests on unalloyed niobium and several niobium-vanadium alloys reveal improvements in stress-controlled fatigue life and decreased low cycle life, in agreement with previous observations on vanadium-hydrogen alloys

  9. Comparison of the effect of neutron irradiation on high purity vanadium and vanadium oxygen alloys

    International Nuclear Information System (INIS)

    Arsenault, R.J.; Bressers, J.

    1977-01-01

    An investigation of the effect of neutron damage on the low temperature deformation characteristics of high purity vanadium (R/sub 300K//R/sub 4.2K/ = 1100) was undertaken for two purposes. One purpose was to determine if reducing the purity interstitial content to a lower level would result in a large difference in the effective stress between irradiated and non-irradiated samples. The present data along with previously obtained data does indicate that the difference increases as the impurity interstitial content is reduced. The explanation of this observation is based on the rapid increase of the non-irradiated yield stress at 77 0 K due to small increases in the oxygen content; however, the increase of the yield stress of the irradiated samples is much less with the same increase in oxygen content. A second purpose of this investigation was to determine the size and density of observable neutron produced defects as a function of oxygen content by transmission electron microscopy, and to relate the changes in density with changes in the yield stress. It was found that the density decreases and the size increases as the oxygen content decreases. There is qualitative agreement between the increase in yield stress at 300 0 K and the observable defect density. However, the change in the yield stress at 77 0 K due to neutron irradiation cannot be related to defect density and size

  10. Vanadium contents in Kazakhstan fossils hydrocarbons by data of nuclear-physical analysis methods

    International Nuclear Information System (INIS)

    Nadirov, N.K.; Solodukhin, V.P.

    1998-01-01

    Investigation of nuclear physical methods possibilities of vanadium determination analysis in organic fossils and an application of these methods for solution of scientific and practical tasks are presented. Vanadium contents in high viscous petroleums and petroleum bituminous rock of different deposits of Western Kazakhstan and carbonaceous shales of Dzhangariya are studied. Presented data evidence that organic fossils of numerous deposits of Kazakhstan have industrial interest because of high vanadium concentration in its contents

  11. Comparison of damage microstructures in neutron-irradiated vanadium and iron

    International Nuclear Information System (INIS)

    Horton, L.L.; Farrell, K.

    1983-01-01

    The cavity morphology and dislocation loop geometry in bcc vanadium are compared with the previously reported observations for neutron-irradiated iron. The specimens were vanadium (V) with 100 wppM of interstitial impurities and vanadium with boron carbide additions (V-B 4 C) which were irradiated to approx. 1 dpa in the same Oak Ridge Research Reactor capsules as the iron specimens

  12. Investigation of possible application of the chromazole KS reagent to the analytical chemistry of vanadium

    International Nuclear Information System (INIS)

    Gordeeva, M.N.; Fedorova, L.N.; Basargin, N.N.; Rozovskij, Yu.G.

    1978-01-01

    Complex formation of vanadium (4) with chromazole KS has been investigated by the spectrophotometric method. It has been found that two complex compounds are formed: Me:R=1:1 (pH=4.0) and Me:R=1:2 (pH=6.2). The chemistry of the interaction of vanadium (4) with chromazole KS has been studied. A method of the photometric determination of vanadium (4) in standard steels and optical glasses has been developed

  13. A process for electrodeposition of layers of niobium, vanadium, molybdenum or tungsten, or of their alloys

    International Nuclear Information System (INIS)

    Diepers, H.; Schmidt, O.

    1977-01-01

    An improvement is proposed for the process for electrodeposition of layers of niobium, vanadium, molybdenum or tungsten or of their alloys from molten-salt electrolytes (fluorid melts) which is to increase the quality of layers in order to obtain regular thickness and smooth surfaces. According to the invention, a pre-separation is executed on an auxiliary cathode before the (preheated) cathode is immersed. The cathode is only charged for separation after the adjustment of a constant anode potential. It is an advantage that the auxiliary cathode is mechanically and electrically connected with the cathode. As an electrolyte, a mixture of niobium fluorides and a eustetic mixture of potassium fluorides, sodium fluorides and lithium fluorides are particularly suitable for the electrodeposition of miobium. (UWI) [de

  14. Electrochemical intercalation of lithium into polypyrrole/silver vanadium oxide composite used for lithium primary batteries

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Won; Popov, Branko N. [Center for Electrochemical Engineering, Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

    2006-10-20

    Hybrid composites of polypyrrole (PPy) and silver vanadium oxide (SVO) used for lithium primary batteries were chemically synthesized by an oxidative polymerization of pyrrole monomer on the SVO surface in an acidic medium. The composite electrode exhibited higher discharge capacity and better rate capability as compared with the pristine SVO electrode. The improvement in electrochemical performance of the composite electrode was due to PPy which accommodates lithium ions and also enhances the SVO utilization. Chronoamperometric and ac-impedance measurements indicated that lithium intercalation proceeds under the mixed control by interfacial charge transfer and diffusion. The enhanced SVO utilization in the composite electrode results from a facilitated kinetics of interfacial charge transfer in the presence of PPy. (author)

  15. Electrochemical intercalation of lithium into polypyrrole/silver vanadium oxide composite used for lithium primary batteries

    Science.gov (United States)

    Lee, Jong-Won; Popov, Branko N.

    Hybrid composites of polypyrrole (PPy) and silver vanadium oxide (SVO) used for lithium primary batteries were chemically synthesized by an oxidative polymerization of pyrrole monomer on the SVO surface in an acidic medium. The composite electrode exhibited higher discharge capacity and better rate capability as compared with the pristine SVO electrode. The improvement in electrochemical performance of the composite electrode was due to PPy which accommodates lithium ions and also enhances the SVO utilization. Chronoamperometric and ac-impedance measurements indicated that lithium intercalation proceeds under the mixed control by interfacial charge transfer and diffusion. The enhanced SVO utilization in the composite electrode results from a facilitated kinetics of interfacial charge transfer in the presence of PPy.

  16. Vanadium purification by transformation to the tetrachloride and reduction by hydrogen. Study of the reduction mechanism

    International Nuclear Information System (INIS)

    Val, Christian

    1968-01-01

    The problem studied here is the production of very high purity metallic vanadium. By analogy with the method used for silicon or germanium production in electronics, the one employed here involves preparing the tetrachloride from the impure metal, purifying it by distillation, an easy process, and finally reducing this tetrachloride with hydrogen to obtain the pure metal. By this technique it has been possible to reduce the impurity content from about 5000 ppm to under 500 ppm and, in particular, to eliminate almost completely the nitrogen which is not removed by the normal purification methods. The author has studied the changes in the morphology of the deposit obtained as a function of the operational conditions. He has determined in particular the conditions leading to the formation of a compact deposit. He has shown that the deposition kinetics are very probably governed by an adsorbed phase reaction at the metal surface, (author) [fr

  17. Microwave assisted growth of nanorods vanadium dioxide VO2 (R): structural and electrical properties

    Science.gov (United States)

    Derkaoui, I.; Khenfouch, M.; Mothudi, B. M.; Moloi, S. J.; Zorkani, I.; Jorio, A.; Maaza, M.

    2018-03-01

    Nanostructured metal oxides have attracted a lot of attention recently owning to their unique structural advantages and demonstrated promising chemical and physical properties for various applications. In this study, we report the structural and electrical properties of vanadium dioxide VO2 (R) prepared via a single reaction microwave (SRC) synthesis. Our results are revealing that the components of VO2 (R) films have a rod-like shape with a uniform size distribution. The nanorods with very smooth and flat surfaces have a typical length of up to 2μm and a width of about several nanometers. The structural investigations reveal the high crystallinity of VO2 (R) ensuring good electrical contact and showing a high conductivity as a function of temperature. This synthesis method provides a new simple route to fabricate one-dimensional nanostructured metal oxides which is suitable for a large field of applications especially for smart windows.

  18. Improved activation cross sections for vanadium and titanium

    International Nuclear Information System (INIS)

    Muir, D.W.; Arthur, E.D.

    1983-01-01

    Vanadium alloys such as V-20Ti and V-Cr-Ti are attractive candidates for use as structural materials in fusion-reactor blankets. The virtual absence of long-lived activation products in these alloys suggest the possibility of reprocessing on an intermediate time scale. We have employed the modern Hauser-Feshbach nuclear-model code GNASH to calculate cross sections for neutron-activation reactions in 50 V and 51 V, to allow a more accurate assessment of induced radioactivity in vanadium alloys. In addition, cross sections are calculated for the reactions 46 Ti(n,2n) and 45 Ti(n,2n) in order to estimate the production of 44 Ti, a 1.2-MeV gamma-ray source with a half-life of 47 years

  19. Vanadium levels in marine organisms of Onagawa Bay in Japan

    International Nuclear Information System (INIS)

    Fukushima, M.; Suzuki, H.; Saito, K.; Chatt, A.

    2009-01-01

    Vanadium in marine organisms from Onagawa Bay in Miyagi, Japan, was determined by an instrumental neutron activation analysis (INAA) method using anticoincidence gamma-ray spectrometry at the Dalhousie University SLOWPOKE-2 Reactor (DUSR) facility in Canada. Seaweeds, cultivated oysters, plankton, and four different species of sea squirt were collected from Onagawa Bay during 2005-2008. Vanadium levels around 20 μg g -1 (dry weight) were found in Japanese tangle and hijiki seaweeds. One species of sea squirt (Ciona savignyi) contained 160-500 ppm of V and it was highest among the four species of sea squirts studied. Protein-bound V species were separated by gel permeation chromatography (GPC) and the element determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). (author)

  20. Effect of vanadium application on the paddy rice

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, T F

    1953-01-01

    The height, the root length and the weight of rice seedlings were increased by the application of ammonium vanadate. The nitrogen contents of seedlings were generally increased in proportion to the amounts of vanadate applied. Carbon contents of seedlings, however, show little difference. The best result was obtained when V/sub 2/O/sub 3/ 150 ppm was applied, but more than 500 ppm was toxic to rice seedlings, and at 1000 ppm all rice seedlings were killed. N, P, and K fertilizers were added to the rice after transplantation from the nursery, but vanadium was omitted. Little difference was found in growth and yield of the rice plants. Vanadium absorbed by younger rice seedlings has little influence on the latter growth and yields of rice plants.

  1. Preparation and characterization of phosphate glasses containing titanium and vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Kaoua, S. [Laboratoire de Chimie du Solide, Faculte des Sciences Ain Chock, Casablanca (Morocco); Krimi, S. [Laboratoire de Chimie du Solide, Faculte des Sciences Ain Chock, Casablanca (Morocco)]. E-mail: krimisaida@yahoo.fr; El Jazouli, A. [Laboratoire de Chimie des Materiaux Solides, Faculte des Sciences Ben M' Sik, Casablanca (Morocco); Hlil, E.K. [Laboratoire de Cristallographie du CNRS, Grenoble (France)]. E-mail: hlil@grenoble.cnrs.fr; Waal, D. de [Department of Chemistry, University of Pretoria, 0002 Pretoria (South Africa)

    2007-02-21

    Na{sub 5-x}Ti{sub 1-x}V {sub x}(PO{sub 4}){sub 3} (0 {<=} x {<=} 1) phosphates glasses have been obtained in air by direct fusion of Na{sub 2}CO{sub 3}, TiO{sub 2}, V{sub 2}O{sub 5} and (NH{sub 4}){sub 2}HPO{sub 4}. Vitreous Na{sub 5}Ti(PO{sub 4}){sub 3} is colourless while the glasses containing vanadium are green, due to the reduction of V{sup 5+} to V{sup 4+}. Glass transition and crystallization temperatures (T {sub g}, T {sub c}) decrease when the amount of vanadium increases. EPR, Raman and UV-vis spectra have been investigated. The results are consistent with the presence of V{sup 4+} ions in distorted octahedra with very strong V-O bond.

  2. Spectrophotometric investigation of vanadium(4) complexing with monoamine complexones

    International Nuclear Information System (INIS)

    Merkulov, D.A.; Kornev, V.I.

    1998-01-01

    Interaction of vanadium(4) with iminodiacetic (H 2 Ida) and methyliminodiacetic (H 2 Mida) acids by μ = 0.1 (NaClO 4 ) and t = 20±2 deg C is studied through the spectrophotometric method. It is established that the process of complex formation in quasi-binary systems due to competitive effect of hydroxide ions depends to a large degree on the ligands concentration and properties. The VOIda, VO(OH)Ida - , VOMida, VO(OH)Mida - complexes are identified. The stability constants logarithms of these complexes are equal correspondingly to 9.81±0.02, 18.19±0.03, 10.15±0.03, 18.34±0.02. The results of the study on the VO 2+ -HIda and VO 2+ -H 2 Mida systems agree well with the regularities, identified by the study on the vanadium(4) complex formation with other complexones of the iminodiacetate series

  3. The electrical properties of semiconducting vanadium phosphate glasses

    International Nuclear Information System (INIS)

    Moridi, G.R.; Hogarth, C.A.; Hekmat Shooar, N.H.

    1984-01-01

    Vanadium phosphate glasses are a group of oxide glasses which show the semiconducting behaviour. In contrast to the conventional glasses, the conduction mechanism in these glasses is electronic, rather than being ionic. Since 1954, when the first paper appeared on the semiconducting properties of these glasses, much work has been carried out on transition-metal-oxide glasses in general, and vanadium phosphate glasses in particular. The mechanism of conduction is basicaly due to the transport of electrons between the transition-metal ions in different valency states. In the present paper, we have reviewed the previous works on the electrical characteristics of P 2 O 5 -V 2 O 5 glasses and also discussed the current theoretical ideas relevant for the interpretation of the experimental data

  4. Structural and thermal properties of vanadium tellurite glasses

    Science.gov (United States)

    Kaur, Rajinder; Kaur, Ramandeep; Khanna, Atul; González, Fernando

    2018-04-01

    V2O5-TeO2 glasses containing 10 to 50 mol% V2O5 were prepared by melt quenching and characterized by X-ray diffraction (XRD), density, Differential Scanning Calorimetry (DSC) and Raman studies.XRD confirmed the amorphous nature of vanadium tellurite samples. The density of the glasses decreases and the molar volume increases on increasing the concentration of V2O5. The thermal properties, such as glass transition temperature Tg, crystallization temperature Tc, and the melting temperature Tm were measured. Tg decreases from a value of 288°C to 232°C. The changes in Tg were correlated with the number of bonds per unit volume, and the average stretching force constant. Raman spectra were used to elucidate the short-range structure of vanadium tellurite glasses.

  5. Study of sulfur and vanadium in heavy petroleum products

    Energy Technology Data Exchange (ETDEWEB)

    Novelli, J.M.

    1982-10-01

    Sulfur compounds in heavy oil fractions (>450/sup 0/C) are studied in the first part of this work. After chemical oxidation by metachloroperbenzoic acid to obtain sulfones, sulfur compounds are analyzed by infrared spectroscopy for their qualitative and quantitative repartition. The method can be applied for the study of sulfur containing molecules before and after structural modifications of petroleum fractions by any chemical refining processes. In a second part vanadium is characterized in asphalt by physicochemical and chemical methods. 80% of the vanadium in a Boscan asphalt is under the form of porphyrins. Different associations are evidenced in petroleum fractions and metalloporphyrins, but the liaison between the vanadyl group and heterocondensate from asphalts is the more frequent.

  6. Spectrophotometric determination of catecholamine using vanadium and eriochrome cyanine r

    International Nuclear Information System (INIS)

    Nagaraja, Padmarajaiah; Shrestha, Ashwinee Kumar; Shivakumar, Anantharaman; Al-Tayar, Naef Ghallab Saeed; Gowda, Avinask K.

    2011-01-01

    highly sensitive spectrophotometric method for the analysis of catecholamine drugs; L-dopa and methyldopa, is described. The analysis is based on the reaction of drug molecules with vanadium (V) which is reduced to vanadium (IV) and form complex with eriochrome cyanine R to give products having maximum absorbance (λ max ) at 565 nm. Beer's law is obeyed in the range 0.028-0.84 and 0.099-0.996 μg mL -1 for L-dopa and methyldopa, respectively. The statistical analysis as well as comparison with reported methods demonstrated high precision and accuracy of the proposed method. The method was successfully applied in the analysis of pharmaceutical preparations. (author)

  7. Work function in niobium, tantalum and vanadium hydrides

    International Nuclear Information System (INIS)

    Kucherov, Ya.R.; Markin, V.Ya.; Savin, V.I.; Topil'skij, N.D.

    1978-01-01

    The concentration dependences of the work function of electrons in hydrides of Nb, Ta and V are presented. The work function of electrons was studied at room temperature by the contact Kelvin potential difference method to an accuracy of +-0.02 eV. The effect of hydrogen on the work function variations in the systems investigated has been analyzed. It is shown that a higher hydrogen concentration in solid solutions based on the Nb-H and Ta-H systems increases the effective total positive dipole moment, whereby the work function decreases. The abnormal changes in the work function in the region of solid solutions of hydrogen in vanadium seem to be due to the specific electronic structure of vanadium and its interaction with hydrogen

  8. Determination of absolute oscillator strengths for doubly-ionized vanadium

    International Nuclear Information System (INIS)

    Goly, A.

    1978-01-01

    Oscillator strengths of thirty V III lines in the wavelength region from 2300A to 2600A were determined by the emission method using a modified wallstabilized cascade are operating at atmospheric pressure in helium with traces of VOCl 3 -vapour. The plasma radiation was analyzed by using a high dispersion grating spectrograph (0.7 A/mm) and Kodak IIaO-plates. Conventional techniques of intensity measurement were employed. Under the physical conditions created the helium plasma was found more or less distant from LTE, but for singly- and doubly-ionized vanadium according to Drawin's criteria, a Boltzmann distribution of level population can be assumed (and has been proved for VII). Measuring a set of intensities of V II lines (with different energies of upper levels) and using gf-values, obtained previously in an argon-vanadium plasma in LTE, excitation temperatures were determined from slopes of Boltzmann plots. (orig.) 891 WL [de

  9. Muon diffusion and trapping studies in high purity vanadium

    International Nuclear Information System (INIS)

    Heffner, R.H.; Brown, J.A.; Hutson, R.L.; Leon, M.; Parkin, D.M.; Schillaci, M.E.; Gauster, W.B.; Carlson, O.N.; Rehbein, D.K.; Fiory, A.T.

    1979-01-01

    The authors present the results of a study of the effects of varying impurity concentration on the temperature dependence of the depolarization rate of positive muons implanted into vanadium. Data are reported for the most highly purified polycrystalline sample yet measured, and the same sample subsequently doped with about 500 ppm oxygen by weight. The data for the pure sample shows a low depolarization rate ( -1 ) at all temperatures measured, showing a broad minimum centered at approximately 35 K, followed by a sharp peak near 90 K and a rapid drop to negligible values at 200 K. The data is contrasted with previously published data on less pure samples, and calls into question previous interpretations of the behavior of the μ + at low temperatures in impure vanadium as one-phonon-assisted tunneling. (Auth.)

  10. Muon diffusion and trapping studies in high purity vanadium

    International Nuclear Information System (INIS)

    Heffner, R.H.; Brown, J.A.; Hutson, R.L.; Leon, M.; Gauster, W.B.; Carlson, O.N.; Rehbein, D.K.; Fiory, A.T.

    1978-01-01

    The first results of a study of the effects of varying impurity concentration on the temperature dependence of the depolarization rate of positive muons implanted into vanadium are presented. Data are reported for the most highly purified polycrystalline sample yet measured, and the same sample subsequently doped with about 500 ppM oxygen by weight. The data for the pure sample shows a low depolarization rate ( -1 ) at all temperatures measured, showing a broad minimum centered at approx. 35 K, followed by a sharp peak near 90 K and a rapid drop to negligible values at 200 K. The data are contrasted with previously published data on less pure samples, and call into question previous interpretations of the behavior of the μ + at low temperatures in impure vanadium as one-phonon-assisted tunneling. 6 references

  11. Recent Development of Nanocomposite Membranes for Vanadium Redox Flow Batteries

    Directory of Open Access Journals (Sweden)

    Sang-Ho Cha

    2015-01-01

    Full Text Available The vanadium redox flow battery (VRB has received considerable attention due to its long cycle life, flexible design, fast response time, deep-discharge capability, and low pollution emissions in large-scale energy storage. The key component of VRB is an ion exchange membrane that prevents cross mixing of the positive and negative electrolytes by separating two electrolyte solutions, while allowing the conduction of ions. This review summarizes efforts in developing nanocomposite membranes with reduced vanadium ion permeability and improved proton conductivity in order to achieve high performance and long life of VRB systems. Moreover, functionalized nanocomposite membranes will be reviewed for the development of next-generation materials to further improve the performance of VRB, focusing on their properties and performance of VRB.

  12. Critical safety features of the vanadium redox flow battery

    Science.gov (United States)

    Whitehead, A. H.; Rabbow, T. J.; Trampert, M.; Pokorny, P.

    2017-05-01

    In this work the behaviour of the vanadium redox flow battery is examined under a variety of short-circuit conditions (e.g. with and without the pumps stopping as a result of the short). In contrast to other battery types, only a small proportion of the electroactive material, in a flow battery, is held between the electrodes at any given time. Therefore, together with the relatively low energy density of the vanadium electrolyte, the immediate release of energy, which occurs as a result of electrical shorting, is somewhat limited. The high heat capacity of the aqueous electrolyte is also beneficial in limiting the temperature rise. It will be seen that the flow battery is therefore considerably safer than other battery types, in this respect.

  13. Additive for vanadium and sulfur oxide capture in catalytic cracking

    International Nuclear Information System (INIS)

    Chin, A.A.; Sapre, A.V.; Sarli, M.S.

    1991-01-01

    This patent describes a fluid catalytic cracking process in which a hydrocarbon feedstock. It comprises: a vanadium contaminant in an amount of a least 2 ppmw is cracked under fluid catalytic cracking conditions with a solid, particulate cracking catalyst to produce cracking products of lower molecular weight while depositing carbonaceous material on the particles of cracking catalyst, separating the particles of cracking catalyst from the cracking products in the disengaging zone and oxidatively regenerating the cracking catalyst by burning off the deposited carbonaceous material in a regeneration zone, the improvement comprising reducing the make-up rate of the cracking catalyst by contacting the cracking feed with a particulate additive composition for passivating the vanadium content of the feed, comprising an alkaline earth metal oxide and an alkaline earth metal spinel

  14. The structural studies of vanadium substituted lithium-bismuth-boro-tellurite glass

    Science.gov (United States)

    Madhu, A.; Eraiah, B.

    2018-05-01

    The structural studies of vanadium substituted lithium-bismuth-boro-tellurite glass is successfully prepared and certain analysis like XRD,FTIR,DTA/TGA with density, molar volume are done. The amorphous phase has been identified based on X-ray diffraction analysis. The vanadium oxide plays the role as a glass-modifier and influences on BO3 ↔ BO4 conversion. The observed nonlinear variation in Tg with vanadium oxide increase, it reflects structural changes. The nonlinear variation of density and molar volume can be attributed to vanadium oxide incorporation have increased the number of Non-bridging oxygen (NBO'S).

  15. A nuclear on-line sensor for continuous control of vanadium content in oil pipelines

    International Nuclear Information System (INIS)

    Rizk, R.A.M.

    1989-01-01

    Trace amounts of vanadium in crude oil and in heavy distillate fuels are very harmful due to their corrosive action. Thus the necessity arises for continuous control of the vanadium content in oil pipelines. Moreover, the development of a nuclear on-line sensor that can continuously analyze the vanadium content in oil pipelines may lead to a better control of processing operations. In this paper a feasibility study for on-line analysis of vanadium in crude oil by means of neutron activation analysis is presented. (author)

  16. Neurobehavioral and cytotoxic effects of vanadium during oligodendrocyte maturation: a protective role for erythropoietin.

    Science.gov (United States)

    Mustapha, Oluwaseun; Oke, Bankole; Offen, Nils; Sirén, Anna-Leena; Olopade, James

    2014-07-01

    Vanadium exposure has been known to lead to lipid peroxidation, demyelination and oligodendrocytes depletion. We investigated behaviour and glial reactions in juvenile mice after early neonatal exposure to vanadium, and examined the direct effects of vanadium in oligodendrocyte progenitor cultures from embryonic mice. Neonatal pups exposed to vanadium via lactation for 15 and 22 days all had lower body weights. Behavioural tests showed in most instances a reduction in locomotor activity and negative geotaxis. Brain analyses revealed astrocytic activation and demyelination in the vanadium exposed groups compared to the controls. In cell culture, exposure of oligodendrocytes to 300 μM sodium metavanadate significantly increased cell death. Expression of the oligodendrocyte specific proteins, 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) and oligodendrocyte specific protein (OSP/Claudin) were reduced upon vanadium treatment while simultaneous administration of erythropoietin (EPO; 4-12 U/ml) counteracted vanadium-toxicity. The data suggest that oligodendrocyte damage may explain the increased vulnerability of the juvenile brain to vanadium and support a potential for erythropoietin as a protective agent against vanadium-toxicity during perinatal brain development and maturation. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Hydrogen Production by Steam Reforming of Natural Gas Over Vanadium-Nickel-Alumina Catalysts.

    Science.gov (United States)

    Yoo, Jaekyeong; Park, Seungwon; Song, Ji Hwan; Song, In Kyu

    2018-09-01

    A series of vanadium-nickel-alumina (xVNA) catalysts were prepared by a single-step sol-gel method with a variation of vanadium content (x, wt%) for use in the hydrogen production by steam reforming of natural gas. The effect of vanadium content on the physicochemical properties and catalytic activities of xVNA catalysts in the steam reforming of natural gas was investigated. It was found that natural gas conversion and hydrogen yield showed volcano-shaped trends with respect to vanadium content. It was also revealed that natural gas conversion and hydrogen yield increased with decreasing nickel crystallite size.

  18. Low-temperature direct synthesis of mesoporous vanadium nitrides for electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hae-Min [Institute of NT-IT Fusion Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499 (Korea, Republic of); Jeong, Gyoung Hwa [Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Banyeon 100, Ulsan 44919 (Korea, Republic of); Kim, Sang-Wook [Department of Molecular Science and Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499 (Korea, Republic of); Kim, Chang-Koo, E-mail: changkoo@ajou.ac.kr [Department of Chemical Engineering and Department of Energy Systems Research, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499 (Korea, Republic of)

    2017-04-01

    Highlights: • Vanadium nitrides were directly synthesized by a one-step chemical precipitation method. • This method was carried out at a low temperature of 70 °C. • Vanadium nitrides had a specific capacitance of 598 F/g. • The equivalent series resistance of the vanadium nitride electrode was 1.42 Ω after 5000 cycles. - Abstract: Mesoporous vanadium nitrides are directly synthesized by a one-step chemical precipitation method at a low temperature (70 °C). Structural and morphological analyses reveal that vanadium nitride consist of long and slender nanowhiskers, and mesopores with diameters of 2–5 nm. Compositional analysis confirms the presence of vanadium in the VN structure, along with oxidized vanadium. The cyclic voltammetry and charge-discharge tests indicate that the obtained material stores charges via a combination of electric double-layer capacitance and pseudocapacitance mechanisms. The vanadium nitride electrode exhibits a specific capacitance of 598 F/g at a current density of 4 A/g. After 5000 charge-discharge cycles, the electrode has an equivalent series resistance of 1.42 Ω and retains 83% of its initial specific capacitance. This direct low-temperature synthesis of mesoporous vanadium nitrides is a simple and promising method to achieve high specific capacitance and low equivalent series resistance for electrochemical capacitor applications.

  19. Optimization of process factors for self-healing vanadium-based conversion coating on AZ31 magnesium alloy

    Science.gov (United States)

    Li, Kun; Liu, Junyao; Lei, Ting; Xiao, Tao

    2015-10-01

    A self-healing vanadium-based conversion coating was prepared on AZ31 magnesium alloy. The optimum operating conditions including vanadia solution concentration, pH and treating temperature for obtaining the best corrosion protective vanadia coatings and improved localized corrosion resistance to the magnesium substrate were determined by an orthogonal experiment design. Surface morphology and composition of the resultant conversion coatings were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The self-healing behavior of the coating was investigated by cross-cut immersion test and electrochemical impedance spectroscopy (EIS) measurements in 3.5% NaCl solution.

  20. Silver Vanadium Phosphorous Oxide, Ag(2)VO(2)PO(4): Chimie Douce Preparation and Resulting Lithium Cell Electrochemistry.

    Science.gov (United States)

    Kim, Young Jin; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

    2011-08-15

    Recently, we have shown silver vanadium phosphorous oxide (Ag(2)VO(2)PO(4), SVPO) to be a promising cathode material for lithium based batteries. Whereas the first reported preparation of SVPO employed an elevated pressure, hydrothermal approach, we report herein a novel ambient pressure synthesis method to prepare SVPO, where our chimie douce preparation is readily scalable and provides material with a smaller, more consistent particle size and higher surface area relative to SVPO prepared via the hydrothermal method. Lithium electrochemical cells utilizing SVPO cathodes made by our new process show improved power capability under constant current and pulse conditions over cells containing cathode from SVPO prepared via the hydrothermal method.

  1. Fast Neutron Elastic and Inelastic Scattering of Vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Holmqvist, B; Johansson, S G; Lodin, G; Wiedling, T

    1969-11-15

    Fast neutron scattering interactions with vanadium were studied using time-of-flight techniques at several energies in the interval 1.5 to 8.1 MeV. The experimental differential elastic scattering cross sections have been fitted to optical model calculations and the inelastic scattering cross sections have been compared with Hauser-Feshbach calculations, corrected for the fluctuation of compound-nuclear level widths.

  2. Solid state bonding of beryllium to copper and vanadium

    International Nuclear Information System (INIS)

    Floyd, D.R.; Liby, A.L.; Weaver, W.

    1993-01-01

    The intent of this effort was to demonstrate that ingot metallurgy (IM) beryllium (Be) can be bonded to dissimilar metals such as copper (Cu) or vanadium (V) at low temperatures by using silver (Ag) as a bonding aid. It is hoped that success at the coupon stage will stimulate more extensive studies of the mechanical and thermal integrity of such joints, leading ultimately to use of this technology to fabricate first wall structures for ITER. (orig.)

  3. Effect of helium on void swelling in vanadium

    International Nuclear Information System (INIS)

    Brimhall, J.L.; Simonen, E.P.

    1975-01-01

    Little difference in void microstructural swelling of vanadium is observed when helium is injected simultaneously with a 46- or 5-MeV nickel beam as compared to no helium injection, at least at high dose rates. At lower dose rates, a strong helium effect is seen when the helium is injected prior to heavy ion bombardment. The effect of the helium is shown to be a strong function of the overall displacement damage rate

  4. Optimization of a Vanadium Redox Flow Battery with Hydrogen generation

    OpenAIRE

    Wrang, Daniel

    2016-01-01

    We consider the modelling and optimal control of energy storage systems, in this study a Vanadium Redox Flow Battery. Such a battery can be introduced in the electrical grid to be charged when demand is low and discharged when demand is high, increasing the overall efficiency of the network while reducing costs and emission of greenhouse gases. The model of the battery proposed in this study is less complex than the majority of models on batteries and energy storage systems found in literatur...

  5. Optical properties of zinc–vanadium glasses doped with samarium ...

    Indian Academy of Sciences (India)

    Abstract. Zinc–vanadium glasses doped with samarium oxide having the chemical composition Sm2O3(x). ZnO(40−x)V2O5(60)(where x = 0·1–0·5 mol%) were prepared by melt quenching method. The density of these glasses was measured by Archimedes method; the corresponding molar volumes have also been ...

  6. Complexes of vanadium (V) oxotrichloride with amides and tertiary amines

    International Nuclear Information System (INIS)

    Paul, R.C.; Sharma, N.C.; Sahi, Y.P.; Chadha, S.L.; Sharma, A.K.

    1975-01-01

    Vanadium(V) oxotrichloride forms dark brown hygroscopic solid complexes of the composition VOCl 3 .3B and VOCl 3 .2B' where B represents pyridine, α-, β-, and γ-picolines, quinoline, isoquinoline, urea, N-methylformamide or acetanilide while B' represents N, N'-dimethylformamide, N-methylacetamide or dimethylacetamide. These complexes have been characterized on the basis of their analytical and IR spectral data. (author)

  7. Kinetic investigation of vanadium (V)/(IV) redox couple on electrochemically oxidized graphite electrodes

    International Nuclear Information System (INIS)

    Wang, Wenjun; Wei, Zengfu; Su, Wei; Fan, Xinzhuang; Liu, Jianguo; Yan, Chuanwei; Zeng, Chaoliu

    2016-01-01

    Highlights: • The VO_2"+/VO"2"+ redox reaction of the electrode could be facilitated to some extent with the increasing anodic corrosion. • A real reaction kinetic equation for the oxidation of VO"2"+ on the electrochemically oxidized electrode has been firstly obtained. • The establishment of the kinetic equation is conducive to predict polarization behaviors of the electrodes in engineering application. - Abstract: The morphology, surface composition, wettability and the kinetic parameters of the electrochemically oxidized graphite electrodes obtained under different anodic polarization conditions have been examined by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), contact angle measurements, steady-state polarization and cyclic voltammetry (CV) tests, with an attempt to investigate the inherent correlation between the physicochemical properties and the kinetic characteristics for carbon electrodes used in an all-vanadium redox flow battery (VRFB). When the anodic polarization potential raises up to 1.8 V vs. SCE, the anodic corrosion of the graphite might happen and a large number of oxygen-containing functional groups generate. The VO_2"+/VO"2"+ redox reaction can be facilitated and the reaction reversibility tends to become better with the increasing anodic potential, possibly owing to the increased surface oxides and the resulting improved wettability of the electrode. Based on this, a real reaction kinetic equation for the oxidation of VO"2"+ has been obtained on the electrode polarized at 1.8 V vs. SCE and it can be also well used to predict the polarization behavior of the oxidized electrode in vanadium (IV) acidic solutions.

  8. Vanadium extraction by combined process of lixiviation and toasting

    International Nuclear Information System (INIS)

    Coral, Aldo

    1992-01-01

    Combinated toasting and leaching processes were applied at laboratory level to vanadiferous ore from Puyango deposit in order to evaluate different rates. Before leaching, a pretreatment consisting in toasting at open atmosphere was given to the ore. Both raw and toasted ore were later washed in organic solvents. In reason of mineralogical and petrographic characteristics of the ore, only alcaline leaching was tested under different pressure temperature and pH conditions of leaching solution (pH=9.8) in order to optimize time and efficiency of each individual process. Four different unitary alcaline leaching processes were studied: MECHANICAL STIRRING, PNEUMATIC STIRRING, LEACHING IN AUTOCLAVE AND LEACHING IN COLUMNS. For these four processes were obtained recovery rates (in percentage) of 18.63 and 87.82; 17.03 and 82.57; 60.42 and 99.55; 2.5 and 30.10; respectively from raw and pre-toasted ore. After filtration, vanadium was extracted from enriched solutions by using liquid resin ALAMINE 336, selective for vanadium at pH=2.8. Vanadium was later discharged with a Sodium Carbonate solution (10 per cent) and finally precipitated as the commercial compound Ammonium Vanadate, NH4VO3. Nuclear techniques as X-ray fluorescence and Atomic Absorption spectroscopy were used for analysis all over the investigation

  9. Performance Modeling of a Vanadium Redox Flow Battery during Discharging

    International Nuclear Information System (INIS)

    Yang, W.W.; He, Y.L.; Li, Y.S.

    2015-01-01

    A two-dimensional quasi-steady-state model is presented to simulate coupled mass-species-charge transfer and electrochemical reactions in all vanadium redox flow battery. Emphasis is located on examining the influences of applied current density, initial vanadium concentration, initial acid concentration and electrolyte flow rate on overpotentials in both electrodes, ohmic loss in electrolyte phase as well as battery discharging voltage. It is indicated that overpotential in negative electrode is the dominant factor causing the loss of battery discharging voltage at relatively lower or higher state of charge, while ohmic loss in electrolyte phase is dominant when discharging at moderate state of charge. Increasing initial vanadium concentration, the battery discharging voltage is significantly increased due to the reduced overpotentials in both electrodes. With the increase in initial acid concentration, the battery discharging voltage is also obviously increased because of increased open circuit voltage and decreased ohmic loss in electrolyte phase. As the electrolyte flow rate increases, the total discharging time is extended due to the retarded concentration polarization and the battery discharging voltage is obviously increased at lower state of charge

  10. A combined theoretical-experimental study of interactions between vanadium ions and Nafion membrane in all-vanadium redox flow batteries

    Science.gov (United States)

    Intan, Nadia N.; Klyukin, Konstantin; Zimudzi, Tawanda J.; Hickner, Michael A.; Alexandrov, Vitaly

    2018-01-01

    Vanadium redox flow batteries (VRFBs) are a promising solution for large-scale energy storage, but a number of problems still impede the deployment of long-lifetime VRFBs. One important aspect of efficient operation of VRFBs is understanding interactions between vanadium species and the membrane. Herein, we investigate the interactions between all four vanadium cations and Nafion membrane by a combination of infrared (IR) spectroscopy and density-functional-theory (DFT)-based static and molecular dynamics simulations. It is observed that vanadium species primarily lead to changes in the IR spectrum of Nafion in the SO3- spectral region which is attributed to the interaction between vanadium species and the SO3- exchange sites. DFT calculations of vanadium -Nafion complexes in the gas phase show that it is thermodynamically favorable for all vanadium cations to bind to SO3- via a contact pair mechanism. Car-Parrinello molecular dynamics-based metadynamics simulations of cation-Nafion systems in aqueous solution suggest that V2+ and V3+ species coordinate spontaneously to SO3-, which is not the case for VO2+ and VO2+ . The interaction behavior of the uncycled membrane determined in this study is used to explain the experimentally observed changes in the vibrational spectra, and is discussed in light of previous results on device-cycled membranes.

  11. Assessing the solubility controls on vanadium in groundwater, northeastern San Joaquin Valley, CA

    Science.gov (United States)

    Wright, Michael T.; Stollenwerk, Kenneth G.; Belitz, Kenneth

    2014-01-01

    The solubility controls on vanadium (V) in groundwater were studied due to concerns over possible harmful health effects of ingesting V in drinking water. Vanadium concentrations in the northeastern San Joaquin Valley ranged from 25 μg/L) and lowest in samples collected from anoxic groundwater (70% 2VO4−. Adsorption/desorption reactions with mineral surfaces and associated oxide coatings were indicated as the primary solubility control of V5+ oxyanions in groundwater. Environmental data showed that V concentrations in oxic groundwater generally increased with increasing groundwater pH. However, data from adsorption isotherm experiments indicated that small variations in pH (7.4–8.2) were not likely as an important a factor as the inherent adsorption capacity of oxide assemblages coating the surface of mineral grains. In suboxic groundwater, accurate SM modeling was difficult since Eh measurements of source water were not measured in this study. Vanadium concentrations in suboxic groundwater decreased with increasing pH indicating that V may exist as an oxycationic species [e.g. V(OH)3+]. Vanadium may complex with dissolved inorganic and organic ligands under suboxic conditions, which could alter the adsorption behavior of V in groundwater. Speciation modeling did not predict the existence of V-inorganic ligand complexes and organic ligands were not collected as part of this study. More work is needed to determine processes governing V solubility under suboxic groundwater conditions. Under anoxic groundwater conditions, SM predicts that aqueous V exists as the uncharged V(OH)3 molecule. However, exceedingly low V concentrations show that V is sparingly soluble in anoxic conditions. Results indicated that V may be precipitating as V3+- or mixed V3+/Fe3+-oxides in anoxic groundwater, which is consistent with results of a previous study. The fact that V appears insoluble in anoxic (Fe reducing) redox conditions indicates that the behavior of V is different than

  12. Electrical properties improvement of multicrystalline silicon solar cells using a combination of porous silicon and vanadium oxide treatment

    International Nuclear Information System (INIS)

    Derbali, L.; Ezzaouia, H.

    2013-01-01

    In this paper, we will report the enhancement of the conversion efficiency of multicrystalline silicon solar cells after coating the front surface with a porous silicon layer treated with vanadium oxide. The incorporation of vanadium oxide into the porous silicon (PS) structure, followed by a thermal treatment under oxygen ambient, leads to an important decrease of the surface reflectivity, a significant enhancement of the effective minority carrier lifetime (τ eff ) and a significant enhancement of the photoluminescence (PL) of the PS structure. We Obtained a noticeable increase of (τ eff ) from 3.11 μs to 134.74 μs and the surface recombination velocity (S eff ) have decreased from 8441 cm s −1 to 195 cm s −1 . The reflectivity spectra of obtained films, performed in the 300–1200 nm wavelength range, show an important decrease of the average reflectivity from 40% to 5%. We notice a significant improvement of the internal quantum efficiency (IQE) in the used multicrystalline silicon substrates. Results are analyzed and compared to those carried out on a reference (untreated) sample. The electrical properties of the treated silicon solar cells were improved noticeably as regard to the reference (untreated) sample.

  13. Preparation of silica nanocomposite anion-exchange membranes with low vanadium-ion crossover for vanadium redox flow batteries

    International Nuclear Information System (INIS)

    Leung, P.K.; Xu, Q.; Zhao, T.S.; Zeng, L.; Zhang, C.

    2013-01-01

    Highlights: • The permeability of vanadium ions through the silica nanocomposite AEM (SNAEM) is ten times lower than that for Nafion 115. • The rates of self-discharge and capacity fading of the VRFB are substantially reduced with the use of the SNAEM. • The Coulombic and energy efficiencies are as high as 92% and 73%, respectively, at 40 mA cm −2 . -- Abstract: Crossover of vanadium ions through the membranes of all-vanadium redox flow batteries (VRFB) is an issue that limits the performance of this type of flow battery. This paper reports on the preparation of a sol–gel derived silica nanocomposite anion exchange membrane (AEM) for VRFBs. The EDS and FT-IR characterizations confirm the presence and the uniformity of the silica nanoparticles formed in the membrane via an in situ sol–gel process. The properties of the obtained membrane, including the ion-exchange capacity, the area resistance, and the water uptake, are evaluated and compared to the pristine AEM and the Nafion cation exchange membrane (CEM). The experimental results show that the permeability of the vanadium ions through the silica nanocomposite AEM is about 20% lower than that of the pristine AEM, and one order of magnitude lower than that of the Nafion CEM. As a result, the rates of self-discharge and the capacity fading of the VRFB are substantially reduced. The Coulombic and energy efficiencies at a current density of 40 mA cm −2 are, respectively, as high as 92% and 73%

  14. The toxicity of vanadium on gastrointestinal, urinary and reproductive system, and its influence on fertility and fetuses malformations

    Directory of Open Access Journals (Sweden)

    Aleksandra Wilk

    2017-09-01

    Additionally, this research identifies the doses of vanadium which lead to pathological alterations becoming visible within tissues. Moreover, this study includes information about the protective efficacy of some substances in view of the toxicity of vanadium.

  15. Effects of gamma irradiations on reactive pulsed laser deposited vanadium dioxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Madiba, I.G., E-mail: madibagiven@gmail.com [UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria (South Africa); Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Émond, N.; Chaker, M. [Institut National de la Recherche Scientifique (INRS),1650 Blvd. Lionel-Boulet, Varennes, Québec J3X1S2 (Canada); Thema, F.T. [UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria (South Africa); iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Tadadjeu, S.I. [iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville campus, PO Box 1906, Bellville, 7530 (South Africa); Muller, U.; Zolliker, P. [Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Braun, A. [ETH Zurich, Swiss Federal Institute of Technology, CH-8057, Zurich (Switzerland); Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Kotsedi, L. [iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); and others

    2017-07-31

    Highlights: • Synthesis of VO{sub 2} thin films by Reactive pulsed laser deposition has been achieved. • Properties VO{sub 2} remain mainly unaffected when subjected to gamma ray doses similar to those encountered during space missions. • The long range crystal structure of VO{sub 2} remains intact upon irradiation on different doses up to 100 kGy. • XPS reveals a shift from V{sup 4+} to V{sup 5+} oxidation state upon irradiation, due to the frenkel pair formation on the surface. • Irradiated films show the characteristic SMT of VO{sub 2}, although the electrical and optical properties are slightly affected. - Abstract: Vanadium oxide films are considered suitable coatings for various applications such as thermal protective coating of small spacecrafts because of their thermochromic properties. While in outer space, such coating will be exposed to cosmic radiations which include γ-rays. To study the effect of these γ-rays on the coating properties, we have deposited vanadium dioxide (VO{sub 2}) films on silicon substrates and subjected them to extensive γ-irradiations with typical doses encountered in space missions. The prevalent crystallographic phase after irradiation remains the monoclinic VO{sub 2} phase but the films preferential orientation shifts to lower angles due to the presence of disordered regions caused by radiations. Raman spectroscopy measurements also evidences that the VO{sub 2} structure is slightly affected by gamma irradiation. Indeed, increasing the gamma rays dose locally alters the crystalline and electronic structures of the films by modifying the V–V inter-dimer distance, which in turns favours the presence of the VO{sub 2} metallic phase. From the XPS measurements of V2p and O1s core level spectra, an oxidation of vanadium from V{sup 4+} towards V{sup 5+} is revealed. The data also reveal a hydroxylation upon irradiation which is corroborated by the vanishing of a low oxidation state peak near the Fermi energy in the

  16. Confirmation of vanadium complex formation using electrospray mass spectrometry and determination of vanadium speciation by sample stacking capillary electrophoresis

    International Nuclear Information System (INIS)

    Chen Zuliang; Owens, Gary; Naidu, Ravendra

    2007-01-01

    Capillary zone electrophoresis (CZE) with UV detection was used to determine vanadium species. Nitrilotriacetic acid (NTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), ethylene glycol-bis(2-aminoethylether)-tetraacetic acid (EGTA) and 2,6-pyridinedicarboxylic acid (PDCA) were investigated to determine whether these ligands formed stable anionic complexes with vanadium. Of all the ligands studied HEDTA was the most suitable ligand because it gave the largest UV response with reasonable migration time. Electrospray mass spectrometry (ES-MS) was used to confirm the formation of [VO 2 (HEDTA)] 2- and [VO(HEDTA)] 1- in solution. An electrolyte containing 25 mM phosphate, 0.25 mM tetradecyltrimethylammonium bromide (TTAB) at pH 5.5 was optimum for the separation of these anionic vanadium complexes. Sample stacking techniques, including large-volume sample stacking (LVSS) and field-amplified sample injection (FASI), were tested to improve the sensitivity. Best sensitivity was obtained using FASI, with detection limits of 0.001 μM, equivalent to 0.4 μg L -1 , for [VO 2 (HEDTA)] 2- and 0.01 μM, equivalent to 3.4 μg L -1 for [VO(HEDTA)] 1- . The utility of the method for the speciation of V(IV) and V(V) was demonstrated using ground water samples

  17. Amphoteric Ion-Exchange Membranes with Significantly Improved Vanadium Barrier Properties for All-Vanadium Redox Flow Batteries.

    Science.gov (United States)

    Nibel, Olga; Rojek, Tomasz; Schmidt, Thomas J; Gubler, Lorenz

    2017-07-10

    All-vanadium redox flow batteries (VRBs) have attracted considerable interest as promising energy-storage devices that can allow the efficient utilization of renewable energy sources. The membrane, which separates the porous electrodes in a redox flow cell, is one of the key components in VRBs. High rates of crossover of vanadium ions and water through the membrane impair the efficiency and capacity of a VRB. Thus, membranes with low permeation rate of vanadium species and water are required, also characterized by low resistance and stability in the VRB environment. Here, we present a new design concept for amphoteric ion-exchange membranes, based on radiation-induced grafting of vinylpyridine into an ethylene tetrafluoroethylene base film and a two-step functionalization to introduce cationic and anionic exchange sites, respectively. During long-term cycling, redox flow cells containing these membranes showed higher efficiency, less pronounced electrolyte imbalance, and significantly reduced capacity decay compared to the cells with the benchmark material Nafion 117. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Confirmation of vanadium complex formation using electrospray mass spectrometry and determination of vanadium speciation by sample stacking capillary electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zuliang [Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095 (Australia)]. E-mail: zuliang.chen@unisa.edu.au; Owens, Gary [Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095 (Australia); Naidu, Ravendra [Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095 (Australia); CRC for Contamination Assessment and Remediation of Environments, Mawson Lakes Boulevard, Mawson Lakes, SA 5095 (Australia)

    2007-02-28

    Capillary zone electrophoresis (CZE) with UV detection was used to determine vanadium species. Nitrilotriacetic acid (NTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), ethylene glycol-bis(2-aminoethylether)-tetraacetic acid (EGTA) and 2,6-pyridinedicarboxylic acid (PDCA) were investigated to determine whether these ligands formed stable anionic complexes with vanadium. Of all the ligands studied HEDTA was the most suitable ligand because it gave the largest UV response with reasonable migration time. Electrospray mass spectrometry (ES-MS) was used to confirm the formation of [VO{sub 2}(HEDTA)]{sup 2-} and [VO(HEDTA)]{sup 1-} in solution. An electrolyte containing 25 mM phosphate, 0.25 mM tetradecyltrimethylammonium bromide (TTAB) at pH 5.5 was optimum for the separation of these anionic vanadium complexes. Sample stacking techniques, including large-volume sample stacking (LVSS) and field-amplified sample injection (FASI), were tested to improve the sensitivity. Best sensitivity was obtained using FASI, with detection limits of 0.001 {mu}M, equivalent to 0.4 {mu}g L{sup -1}, for [VO{sub 2}(HEDTA)]{sup 2-} and 0.01 {mu}M, equivalent to 3.4 {mu}g L{sup -1} for [VO(HEDTA)]{sup 1-}. The utility of the method for the speciation of V(IV) and V(V) was demonstrated using ground water samples.

  19. Tuning the conductivity of vanadium dioxide films on silicon by swift heavy ion irradiation

    Directory of Open Access Journals (Sweden)

    H. Hofsäss

    2011-09-01

    Full Text Available We demonstrate the generation of a persistent conductivity increase in vanadium dioxide thin films grown on single crystal silicon by irradiation with 1 GeV 238U swift heavy ions at room temperature. VO2 undergoes a temperature driven metal-insulator-transition (MIT at 67 °C. After room temperature ion irradiation with high electronic energy loss of 50 keV/nm the conductivity of the films below the transition temperature is strongly increased proportional to the ion fluence of 5·109 U/cm2 and 1·1010 U/cm2. At high temperatures the conductivity decreases slightly. The ion irradiation slightly reduces the MIT temperature. This observed conductivity change is persistent and remains after heating the samples above the transition temperature and subsequent cooling. Low temperature measurements down to 15 K show no further MIT below room temperature. Although the conductivity increase after irradiation at such low fluences is due to single ion track effects, atomic force microscopy (AFM measurements do not show surface hillocks, which are characteristic for ion tracks in other materials. Conductive AFM gives no evidence for conducting ion tracks but rather suggests the existence of conducting regions around poorly conducting ion tracks, possible due to stress generation. Another explanation of the persistent conductivity change could be the ion-induced modification of a high resistivity interface layer formed during film growth between the vanadium dioxide film and the n-Silicon substrate. The swift heavy ions may generate conducting filaments through this layer, thus increasing the effective contact area. Swift heavy ion irradiation can thus be used to tune the conductivity of VO2 films on silicon substrates.

  20. 77 FR 54897 - Ferrovanadium and Nitrided Vanadium from the Russian Federation: Revocation of Antidumping Duty...

    Science.gov (United States)

    2012-09-06

    ... foreseeable time.\\5\\ \\5\\ See ITC Final and Ferrovanadium and Nitrided Vanadium From Russia: Investigation No... nitrided vanadium from the Russian Federation (Russia) would not be likely to lead to continuation or... foreseeable time,\\1\\ the Department of Commerce (the Department) is publishing this notice of revocation of...

  1. Anthropogenic vanadium emissions to air and ambient air concentrations in North-West Europe

    NARCIS (Netherlands)

    Visschedijk, A.H.J.; Denier van der Gon, H.A.C.; Hulskotte, J.H.J.; Quass, U.

    2013-01-01

    An inventory of Vanadium emissions for North-West Europe for the year 2005 was made based on an identification of the major sources. The inventory covers Belgium, Germany, Denmark, France, United Kingdom, Luxembourg, Netherlands and the OSPAR region of the North Sea. Vanadium emission were

  2. Study using macroscopic autoradiography of the distribution of vanadium 48 in the rat and mouse

    International Nuclear Information System (INIS)

    Serhrouchni, M.

    1982-07-01

    Study of vanadium 48 distribution in the laboratory animal by macroscopic autoradiography. Vanadium 48 bioavailability is zero after oral administration and good after pulmonary administration. It is distributed throughout the body with a particular affinity for bone and teeth. Study of perinatal metabolism [fr

  3. Studies in transition metal chemistry ; V. Soluble Ziegler-type catalysts based on vanadium, part 1

    NARCIS (Netherlands)

    Liefde Meijer, H.J. de; Hurk, J.W.G. van den; Kerk, G.J.M. van der

    1966-01-01

    Experiments are described aiming at a simplification of the catalyst system originally consisting of a mixture of tetraphenyltin, aluminium bromide and vanadium tetrachloride (or vanadium oxytrichloride). It is shown that tetraphenyltin merely acts as a phenylating agent for the aluminium bromide

  4. Gastroprotective effect of vanadium in rats - the roles of gastric acid ...

    African Journals Online (AJOL)

    Stimulation with histamine caused significant increases in gastric output by 187.72%, 57.40% and 78.69% in control, 50 and 200 ppm V respectively and was significantly reduced in the vanadium treated groups. A significant decrease in H+K+ ATPase (proton) pump activities of the vanadium exposed groups compared ...

  5. Vanadium Mining and Cattle Health : Sentinel studies, epidemiological and veterinary public health issues

    NARCIS (Netherlands)

    Gummow, B.

    2005-01-01

    The thesis covers a field outbreak investigation into the cause and pathogenesis of "illthrift" on a dairy farm that was due to vanadium exposure, it examines methods of treating vanadium poisoning in cattle using an experimental study, looks at the use of cattle as sentinels for detecting and

  6. Determination of titanium and vanadium in aqueous solutions by potentiometric titration

    International Nuclear Information System (INIS)

    Sibirkin, A.A.; Elliev, Yu.E.

    1996-01-01

    Possibility of titanium and vanadium determination at their combined presence by bichromatometric chromometric titration with potentiometric indication of end point is shown. The technique is developed which allows to determine titanium and vanadium with relative standard derivation ±2% in amounts not less than 50 and 100 mg respectively

  7. Adsorption Behavior of Vanadium in Presence of alumina with Emphasize on Triple Layer Model Simulation

    International Nuclear Information System (INIS)

    El-Sayed, A.A.

    2006-01-01

    Adsorption behavior of vanadium in alumina colloidal solution as simulation for soil-water and/or sediment - water system was investigated. factors affecting this behavior including Ph, humic acid and alumina concentrations were studied. Three stages of vanadium adsorption on alumina were approved due to Ph changes. The first is increasing adsorption with increasing Ph, in the range 1-3. the second is decreasing adsorption with increasing Ph in the range 6-10. the third is constant adsorption at 100% adsorption in Ph range 3-8 at 10 g/l concentration of alumina. However, at 0.2 g/l, the maximum adsorption of vanadium became less than 100%.The effect of humic acid on the adsorption behavior of vanadium (V) was studied and compared with that of vanadium (IV) . Adsorption behaviors were studied at concentration 4.1 E-4 M for vanadium at 0.1 M ionic strength. Triple layer model was used for simulation of vanadium adsorption behavior in presence of alumina under the same working conditions. the results showed good validation and verification to the data practically found. speciation of vanadium in both homogenous and heterogeneous systems was also studied theoretically so as to verify the most abundant elemental species and its impact on the environment

  8. Synthesis of nanoparticles of vanadium carbide in the ferrite of nodular cast iron

    CERN Document Server

    Fras, E; Guzik, E; Lopez, H

    2005-01-01

    The synthesis method of nanoparticles of vanadium carbide in nodular cast iron is presented. After introduction of this method, the nanoparticles with 10-70 nm of diameter was obtained in the ferrite. The diffraction investigations confirmed that these particles are vanadium carbides of type V/sub 3/C/sub 4/.

  9. Determination of Vanadium Binding Mode on Seawater-Contacted Polyamidoxime Adsorbents

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhicheng [Lawrence Berkeley National Laboratory (LBNL); Rao, Linfeng [Lawrence Berkeley National Laboratory (LBNL); Abney, Carter W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bryantsev, Vyacheslav [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ivanov, Aleksandr [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-09-01

    Adsorbents developed for the recovery of uranium from seawater display poor selectivity over other transition metals present in the ocean, with vanadium particularly problematic. To improve selectivity, an indispensable step is the positive identification of metal binding environments following actual seawater deployment. In this work we apply x-ray absorption fine structure (XAFS) spectroscopy to directly investigate the vanadium binding environment on seawater-deployed polyamidoxime adsorbents. Comparison of the x-ray absorption near edge spectra (XANES) reveal marked similarities to recently a reported non-oxido vanadium (V) structure formed upon binding with cyclic imidedioxime, a byproduct of generating amidoxime functionalities. Density functional theory (DFT) calculations provided a series of putative vanadium binding environments for both vanadium (IV) and vanadium (V) oxidation states, and with both amidoxime and cyclic imidedioxime. Fits of the extended XAFS (EXAFS) data confirmed vanadium (V) is bound exclusively by the cyclic imidedioxime moiety in a 1:2 metal:ligand fashion, though a modest structural distortion is also observed compared to crystal structure data and computationally optimized geometries which is attributed to morphology effects from the polymer graft chain and the absence of crystal packing interactions. These results demonstrate that improved selectivity for uranium over vanadium can be achieved by suppressing the formation of cyclic imidedioxime during preparation of polyamidoxime adsorbents for seawater uranium recovery.

  10. The Influence of Vanadium on Ferrite and Bainite Formation in a Medium Carbon Steel

    Science.gov (United States)

    Sourmail, T.; Garcia-Mateo, C.; Caballero, F. G.; Cazottes, S.; Epicier, T.; Danoix, F.; Milbourn, D.

    2017-09-01

    The influence of vanadium additions on transformation kinetics has been investigated in a medium carbon forging steel. Using dilatometry to track transformation during continuous cooling or isothermal transformation, the impact of vanadium on both ferrite-pearlite and bainite has been quantified. Transmission electron microscopy and atom probe tomography have been used to establish whether vanadium was present in solid solution, or as clusters and precipitates. The results show that vanadium in solid solution has a pronounced retarding influence on ferrite-pearlite formation and that, unlike in the case of niobium, this effect can be exploited even during relatively slow cooling. The influence on bainite transformation was found to depend on temperature; an explanation in terms of the effect of vanadium on heterogeneous nucleation is tentatively proposed.

  11. Temperature dependence of the damage microstructures in neutron-irradiated vanadium

    International Nuclear Information System (INIS)

    Horton, L.L.; Farrell, K.

    1983-01-01

    Vanadium and vanadium with boron carbide additions (V-B 4 C) were irradiated to approx. 1 dpa in the Oak Ridge Research Reactor at controlled temperatures ranging from 455 to 925 K. The V-B 4 C alloy was enriched in 10 B, which produced approx. 3900 at. ppM helium. In the vanadium specimens, the dislocation microstructures varied from clusters of small ( . The V-B 4 C specimens contained only tangled dislocation segments. Cavities were observed in all specimens. The cavity concentration decrease and the average diameter increased with increasing irradiation temperature. At 725 K, the maximum swelling was observed in both the vanadium (0.1%) and V-B 4 C (1.4%). At comparable temperatures the cavities in the V-B 4 C specimens were smaller and more numerous than those in the vanadium specimens. Helium bubbles were found on the grain boundaries in all of the V-B 4 specimens

  12. Ferrocenometric deterrination of vanadium and iron in the presence of each other

    International Nuclear Information System (INIS)

    Malyuta, V.F.; Solomatin, V.T.; Nemodruk, A.A.

    1983-01-01

    Real redox potentials have been measured for the V(4)/V(3), Fe(3)/Fe(2) and Fec + /Fec systems in HCl-H 3 PO 4 and H 2 SO 4 -H 3 PO 4 aqueous solutions. The mechanism is suggested for the reduction of vanadium (4) with ferrocene in the presence of iron (3). The possibility has been shown of differential titration of vanadium (4) and iron (3) by ferrocene in the presence of each other in aqueous solutions. A procedure of determining vanadium in steel and a procedure of determining vanadium and iron in ferrovanadium, vanadium slags and cobalt-based alloys have been worked out by the method of potentiometric and amperometric titration with ferrocene solution

  13. Vanadium determination in raw materials and products of aluminium production using pulse polarography

    International Nuclear Information System (INIS)

    Grigor'eva, M.F.; Bal'de, I.; Markovich, I.A.

    1992-01-01

    Possibility of using differential pulse polarography (DPP) for determination of vanadium in raw materials and products of aluminium production was studied. Ammonium-cheoride buffer solution with pH 9-10, aqueous solution of mixture of sodium carbonate and borax (1:3) and rhodanide-acefic acid solutions (1:1) were tested as a background. Current-voltage curves of vanadium reduction were plotted and peak potentials on DPP were determined against the background of chosen electrolytes. Effect of parameters, providing the maximal height of DPP peak, on the height of measured signal, was studied. Rhodanide background was chosen for polarographic determination of vanadium, because the detection limit of vanadium was the lowest against this background. Pulse polarography enafles to determine vanadium in products of aluminium production in amounts from 1x10 -4 to 0.01 % and more

  14. Analysis of soil reference materials for vanadium(+5) species by electrothermal atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Mandiwana, Khakhathi L.; Panichev, Nikolay

    2010-01-01

    Solid Certified Reference Materials (CRMs) with known vanadium(+5) content are currently not commercially available. Because of this, vanadium species have been determined in solid CRMs of soil, viz. CRM023-50, CRM024-50, CRM049-50, SQC001 and SQC0012. These CRMs are certified with only total vanadium content. Vanadium(+5) was extracted from soil reference materials with 0.1 M Na 2 CO 3 . The quantification of V(+5) was carried out by electrothermal atomic absorption spectrometry (ET-AAS). The concentration of V(+5) in the analyzed CRMs was found to be ranging between 3.60 and 86.0 μg g -1 . It was also found that SQC001 contains approximately 88% of vanadium as V(+5) species. Statistical evaluation of the results of the two methods by paired t-test was in good agreement at 95% level of confidence.

  15. Optimization of conditions for growth of vanadium dioxide thin films on silicon by pulsed-laser deposition

    Science.gov (United States)

    Shibuya, Keisuke; Sawa, Akihito

    2015-10-01

    We systematically examined the effects of the substrate temperature (TS) and the oxygen pressure (PO2) on the structural and optical properties polycrystalline V O2 films grown directly on Si(100) substrates by pulsed-laser deposition. A rutile-type V O2 phase was formed at a TS ≥ 450 °C at PO2 values ranging from 5 to 20 mTorr, whereas other structures of vanadium oxides were stabilized at lower temperatures or higher oxygen pressures. The surface roughness of the V O2 films significantly increased at growth temperatures of 550 °C or more due to agglomeration of V O2 on the surface of the silicon substrate. An apparent change in the refractive index across the metal-insulator transition (MIT) temperature was observed in V O2 films grown at a TS of 450 °C or more. The difference in the refractive index at a wavelength of 1550 nm above and below the MIT temperature was influenced by both the TS and PO2, and was maximal for a V O2 film grown at 450 °C under 20 mTorr. Based on the results, we derived the PO2 versus 1/TS phase diagram for the films of vanadium oxides, which will provide a guide to optimizing the conditions for growth of V O2 films on silicon platforms.

  16. Optimization of conditions for growth of vanadium dioxide thin films on silicon by pulsed-laser deposition

    Directory of Open Access Journals (Sweden)

    Keisuke Shibuya

    2015-10-01

    Full Text Available We systematically examined the effects of the substrate temperature (TS and the oxygen pressure (PO2 on the structural and optical properties polycrystalline V O2 films grown directly on Si(100 substrates by pulsed-laser deposition. A rutile-type V O2 phase was formed at a TS ≥ 450 °C at PO2 values ranging from 5 to 20 mTorr, whereas other structures of vanadium oxides were stabilized at lower temperatures or higher oxygen pressures. The surface roughness of the V O2 films significantly increased at growth temperatures of 550 °C or more due to agglomeration of V O2 on the surface of the silicon substrate. An apparent change in the refractive index across the metal–insulator transition (MIT temperature was observed in V O2 films grown at a TS of 450 °C or more. The difference in the refractive index at a wavelength of 1550 nm above and below the MIT temperature was influenced by both the TS and PO2, and was maximal for a V O2 film grown at 450 °C under 20 mTorr. Based on the results, we derived the PO2 versus 1/TS phase diagram for the films of vanadium oxides, which will provide a guide to optimizing the conditions for growth of V O2 films on silicon platforms.

  17. Effect of vanadium of mechanical behavior, machinability and wear resistance of aluminium grain refined by Ti+B

    International Nuclear Information System (INIS)

    Zaid, A.I.O.; Hamid, A.A.A.

    1999-01-01

    It is well established that aluminum and its alloys are industrially grain refined by adding either Ti or Ti-B to improve their mechanical behavior and surface finish. In a previous paper, it was found that the grain refining efficiency of aluminum master alloys containing Ti or Ti+B was enhanced by addition of small amounts of other elements including vanadium. V. Therefore, it is anticipated that such an element will improve mechanical behavior, machinability and wear resistance of aluminum and its alloys. In this paper, the effect of vanadium addition, up to 0.3% on mechanical behavior is investigated. Machinability was assessed under different cutting conditions: speed, feed and depth of cut and finally the wear resistance was determined at different loads and speeds. The results indicated that improvement in hardness and mechanical strength were achieved by the addition of V that addition of more than 0.2%V resulted in little or no improvement. Similarly, addition of V resulted in improvement of surface quality under the different cutting conditions of speed, feed and depth of cut, and resistance to wear. However addition of more than 0.2% V resulted in increase of wear rate and change of wear mechanisms. (author)

  18. The Balance of Titanium and Vanadium in the Blast Furnace with the Use of Sinter Containing a Titanium-Vanadium-Magnetite Concentrate

    Directory of Open Access Journals (Sweden)

    Budzik, R.

    2007-01-01

    Full Text Available The investigation concerned the use of sinter containing a titanium-vanadium-magnetite concentrate for the production of pig iron. Sinter containing 0,46 to 0,51 % TiO2 and 0,056 to 0,060 % vanadium was used for pig iron production in the blast furnace. Introducing 200 kg of this concentrate to the1 Mg sinter mix did not cause any deterioration of sinter quality.

  19. Effect of vanadium contamination on the framework and micropore structure of ultra stable Y-zeolite.

    Science.gov (United States)

    Etim, U J; Xu, B; Ullah, Rooh; Yan, Z

    2016-02-01

    Y-zeolites are the main component of fluid catalytic cracking (FCC) catalyst for conversion of crude petroleum to products of high demand including transportation fuel. We investigated effects of vanadium which is present as one of the impurities in FCC feedstock on the framework and micropore structure of ultra-stable (US) Y-zeolite. The zeolite samples were prepared and characterized using standard techniques including: (1) X-ray diffraction, (2) N2 adsorption employing non local density functional theory method, NLDFT, (3) Transmittance and Pyridine FTIR, (4) Transmittance electron microscopy (TEM), and (5) (27)Al and (29)Si MAS-NMR. Results revealed that in the presence of steam, vanadium caused excessive evolution of non inter-crystalline mesopores and structural damage. The evolved mesopore size averaged about 25.0nm at 0.5wt.% vanadium loading, far larger than mesopore size in zeolitic materials with improved hydrothermal stability and performance for FCC catalyst. A mechanism of mesopore formation based on accelerated dealumination has been proposed and discussed. Vanadium immobilization experiments conducted to mitigate vanadium migration into the framework clearly showed vanadium is mobile at reaction conditions. From the results, interaction of vanadium with the passivator limits and decreases mobility and activity of vanadium into inner cavities of the zeolite capable of causing huge structure breakdown and acid sites destruction. This study therefore deepens insight into the causes of alteration in activity and selectivity of vanadium contaminated catalyst and hints on a possible mechanism of passivation in vanadium passivated FCC catalyst. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Enrichment, Distribution of Vanadium-Containing Protein in Vanadium-Enriched Sea Cucumber Apostichopus japonicus and the Ameliorative Effect on Insulin Resistance.

    Science.gov (United States)

    Liu, Yanjun; Zhou, Qingxin; Zhao, Yanlei; Wang, Yiming; Wang, Yuming; Wang, Jingfeng; Xu, Jie; Xue, Changhu

    2016-05-01

    Sea cucumbers are a potential source of natural organic vanadium that may improve insulin resistance. In this work, vanadium was accumulated rapidly in blood, body wall, and intestine by sea cucumber Apostichopus japonicus. Furthermore, water-soluble vanadium-containing proteins, the main form of the organic vanadium, were tentatively accumulated and isolated by a bioaccumulation experiment. It was also designed to evaluate the beneficial effect of vanadium-containing proteins (VCPs) from sea cucumber rich in vanadium on the development of hyperglycemia and insulin resistance in C57BL/6J mice fed with a high-fat high-sucrose diet (HFSD). HFSD mice treated with VCPs significantly decreased fasting blood glucose, serum insulin, and HOMA-IR values as compared to HFSD mice, respectively. Serum adiponectin, resistin, TNF-α, and leptin levels in insulin-resistant mice were dramatically reduced by a VCP supplement. These results show an ameliorative effect on insulin resistance by treatment with VCPs. Such compound seems to be a valuable therapy to achieve and/or maintain glycemic control and therapeutic agents in the treatment arsenal for insulin resistance and type 2 diabetes.

  1. Effect of vanadium on germination and seedling growth of lettuce (Lactuca sativa L. C. V. salad bowl)

    Energy Technology Data Exchange (ETDEWEB)

    Lepp, N.W.

    1977-01-01

    The effect of vanadium, applied as VOSO/sub 4/, on germination and subsequent seedling growth of Lettuce has been studied. No differences in germination were observed at any of the applied vanadium concentrations, when compared to a vanadium-free control. Subsequent seedling growth, however, was significantly inhibited by all vanadium treatments. Reductions in shoot growth, root growth and fresh weight were apparent. Similar, but less dramatic effects were observed when 3 day old seedlings were transferred to vanadium enriched media. 13 references, 2 tables.

  2. Obtaining uranium and/or vanadium values from solutions

    Energy Technology Data Exchange (ETDEWEB)

    Vojkovic, M

    1982-04-22

    A process for the recovery of at least one of uranium and vanadium from an aqueous liquor is claimed. It comprises: (a) treating the liquor with a low molecular weight completely water-miscible solvent selected from the group consisting of methanol, iso-propyl alcohol or acetone to form at least two phases; (b) separating the phases; (c) recovering the solvent from the first phase as the azeotropic solvent/water mixture by simple, non-fractional distillation and recycling the mixture to step (a); and (d) recovering metal values from a second one of the phases.

  3. Periodic arrays of pinning centers in thin vanadium films.

    Energy Technology Data Exchange (ETDEWEB)

    Brueck, S. R. J.; Chung, K.; Crabtree, G.; DeLong, L. E.; Hesketh, P. J.; Ilic, B.; Metlushko, V.; Watkins, B.; Welp, U.; Zhang, Z.

    1997-07-13

    Commensurability effects between the superconducting flux line lattice and a square lattice (period d=1{micro}m and diameter D=0.4{micro}m) of submicron holes in 1500 {angstrom} vanadium films were studied by atomic force microscopy, DC magnetization, AC susceptibility, magnetoresistivity and I-V measurements. Peaks in the magnetization and critical current at matching fields are found to depend nonlinearly upon the value of external AC field or current, as well as the inferred symmetry of the flux line lattice.

  4. Vanadium determination in pretoleum by neutron activation analysis

    International Nuclear Information System (INIS)

    Lopez, M.; Espinosa, R.

    1983-01-01

    The vanadium concentration in an Peruvian petroleum sample is determined by neutron activation analysis. The samples were irradiated for 20 minutes with a flux of thermal neutrons of 1.75 x 10 7 n/cm 2 -s in a subcritical assembly. The activity of the created samples decreases to half 15 minutes after the irradiation. The result is 28.3 +- 0.8 p.p.m. with a typical deviation of 2.8%. The detection limit of this method is 4 p.p.m

  5. Growth of Vanadium Carbide by Halide-Activated Pack Diffusion

    DEFF Research Database (Denmark)

    Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Dahl, Kristian Vinter

    The present work investigates growth of vanadium carbide (VC) layers by the pack diffusion method on a Vanadis 6 tool steel. The VC layers were produced by pack diffusion at 1000°C for 1, 4 and 16 hours. The VC layers were characterized with optical and electron microscopy, Vickers hardness tests...... and X-ray diffraction. Homogeneous VC mono-phase layers with Vickers hardness of more than 2400 HV were obtained. Hardening and tempering of the vanadized Vanadis 6 steel did not affect the VC layers....

  6. Hysteresis Phenomena in Sulfur Dioxide Oxidation over Supported Vanadium Catalysts

    DEFF Research Database (Denmark)

    Masters, Stephen G.; Eriksen, Kim Michael; Fehrmann, Rasmus

    1997-01-01

    Catalyst deactivation and hysteresis behavior in industrial SO2-oxidation catalysts have been studied in the temperature region 350-480 C by combined in situ EPR spectroscopy and catalytic activity measurements. The feed gas composition simulated sulfuric acid synthesis gas and wet/dry de......NOx'ed flue gas. The vanadium (IV) compound K4(VO)3(SO4)5 precipitated during all the investigated conditions hence causing catalyst deactivation. Hysteresis behavior of both the catalytic activity and the V(IV) content was observed during reheating....

  7. Preparation and characterization of vanadium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Monfort, O.; Plesch, G. [Comenius University of Bratislava, Faculty of Natural Sciences, Department of Inorganic Chemistry, 84215 Bratislava (Slovakia); Roch, T. [Comenius University of Bratislava, Faculty of Mathematics Physics and Informatics, Department of Experimental Physics, 84248 Bratislava (Slovakia)

    2013-04-16

    The thermotropic VO{sub 2} films have many applications, since they exhibit semiconductor-conductor switching properties at temperature around 70 grad C. Vanadium oxide thin films were prepared via sol-gel method. Spin coater was used to depose these films on Si/SiO{sub 2} and lime glass substrates. Thin films of V{sub 2}O{sub 5} can be reduced to metastable VO{sub 2} thin films at the temperature of 450 grad C under the pressure of 10{sup -2} Pa. These films are then converted to thermotropic VO{sub 2} at 700 grad C in argon under normal pressure. (authors)

  8. Electromigration of hydrogen and deuterium in vanadium, niobium, and tantalum

    International Nuclear Information System (INIS)

    Jensen, C.L.

    1977-10-01

    The electric mobility and effective valence of hydrogen and deuterium in vanadium, niobium, tantalum and three niobium-tantalum alloys were measured. A resistance technique was used to directly determine the electric mobility of hydrogen and deuterium at 30 0 C while a steady-state method was used to measure the effective valence. The use of mass spectrographic techniques on a single specimen which contained both hydrogen and deuterium greatly increased the precision with which the isotope effect in the effective valence could be measured

  9. Medium carbon vanadium micro alloyed steels for drop forging

    International Nuclear Information System (INIS)

    Jeszensky, Gabor; Plaut, Ronald Lesley

    1992-01-01

    Growing competitiveness of alternative manufacturing routes requires cost minimization in the production of drop forged components. The authors analyse the potential of medium carbon, vanadium microalloyed steels for drop forging. Laboratory and industrial experiments have been carried out emphasizing deformation and temperature cycles, strain rates and dwell times showing a typical processing path, associated mechanical properties and corresponding microstructures. The steels the required levels of mechanical properties on cooling after forging, eliminating subsequent heat treatment. The machinability of V-microalloyed steels is also improved when compared with plain medium carbon steels. (author)

  10. Synthesis of vanadium oxide powders by evaporative decomposition of solutions

    International Nuclear Information System (INIS)

    Lawton, S.A.; Theby, E.A.

    1995-01-01

    Powders of the vanadium oxides V 2 O 4 , V 6 O 13 , and V 2 O 5 were produced by thermal decomposition of aqueous solutions of vanadyl sulfate hydrate in atmospheres of N 2 , H 2 mixed with N 2 , or air. The composition of the oxide powder was determined by the reactor temperature and gas composition. Residual sulfur concentrations in powders produced by decomposition at 740 C were less than 1 at.%, and these powders consisted of hollow, roughly spherical aggregates of particles less than 1 microm in diameter

  11. Electron spin resonance of vanadium(4)-thallium(1) dithiocarbamate complexes

    International Nuclear Information System (INIS)

    Ivanov, A.V.; Solozhenkin, P.M.; Baratova, Z.R.; Klyashtornyj, V.B.; Uskov, V.Yu.

    1990-01-01

    Heteronuclear vanadium(4), thallium(1) dithiocarbanate complexes of the composition TlVO(Dtc) 3 and Tl 2 VO(Dtc) 4 under conditions of magnetic dilution were studied by ESR spectroscopy. Magnetically diluted complexes were prepared by coprecipitation from aqueous solutions of thallium(1) and oxovanadium(2) by solutions of sodium diethyldithiocarbamate, dibutyldithiocarbamate, hexamethylenedithiocarbamate, taken in superstoichiometric excess. Analysis of parameters of ESR spectra of the complexes synthesized shows that thallium atoms are not included in the first coordination sphere of oxovanadium(2), and chelate node VS 4 in thallium(1) complex lattice practically preserves its plane quadratic structure

  12. Structure and vibrational properties of oxyhalides of Vanadium

    International Nuclear Information System (INIS)

    Allaf, A.

    2010-01-01

    We study the structure and vibrational modes of a wide range of oxyhalides of vanadium (VOX n Y m ; X, Y) = F, Cl, Br, I; n, m = 0-3, n + m≤ 3). The results agree well with experimental results for VOCl 3 and VOF 3 and suggest reassignment of the experimentally observed VOF to VOF 2 . We provide new assignments for various experimental modes, identifying several intermediates (VOBr 2 , VOBr) and mixed structures (e.g., VOCl 2 Br), and discuss formation trends and stabilities.(author)

  13. Determination of total vanadium and vanadium(V) in groundwater from Mt. Etna and estimate of daily intake of vanadium(V) through drinking water.

    Science.gov (United States)

    Arena, Giovanni; Copat, Chiara; Dimartino, Angela; Grasso, Alfina; Fallico, Roberto; Sciacca, Salvatore; Fiore, Maria; Ferrante, Margherita

    2015-06-01

    Vanadium(V) can be found in natural waters in the form of V(IV) and V(V) species, which have different biological properties and toxicity. The purpose of this study was to determine the concentrations of total V and V(V) in groundwater from the area of Mt. Etna and to assess the estimated daily intake (EDI) of V(V) of adults and children through drinking water. Water was sampled monthly at 21 sites in 2011. Total vanadium was determined by inductively coupled plasma-mass spectrometry (ICP-MS) and speciation by ion chromatography-ICP-MS (IC-ICP-MS). The concentration of V(V) species ranged from 62.8 to 98.9% of total V, with significantly higher concentrations in samples from the S/SW slope of Mt. Etna. The annual mean concentrations of total V exceeded the Italian legal limit of 140 μg/L at four sites on the S/SW slope. In the absence of thresholds for V(V) intake, only the Environmental Protection Agency (EPA) has calculated a reference dose. Children's EDI of V(V) at the sites with the higher V concentrations exceeded EPA thresholds (9 μg/kg/day). In particular, we found in Camporotondo, Mascalucia, Ragalna and San Pietro Clarenza sites children's EDIs of 11, 9.3, 11 and 9.9, respectively. The EDI of V(V) was significantly higher than the literature range (0.09-0.34 μg/kg/day).

  14. Validating and improving a zero-dimensional stack voltage model of the Vanadium Redox Flow Battery

    Science.gov (United States)

    König, S.; Suriyah, M. R.; Leibfried, T.

    2018-02-01

    Simple, computationally efficient battery models can contribute significantly to the development of flow batteries. However, validation studies for these models on an industrial-scale stack level are rarely published. We first extensively present a simple stack voltage model for the Vanadium Redox Flow Battery. For modeling the concentration overpotential, we derive mass transfer coefficients from experimental results presented in the 1990s. The calculated mass transfer coefficient of the positive half-cell is 63% larger than of the negative half-cell, which is not considered in models published to date. Further, we advance the concentration overpotential model by introducing an apparent electrochemically active electrode surface which differs from the geometric electrode area. We use the apparent surface as fitting parameter for adapting the model to experimental results of a flow battery manufacturer. For adapting the model, we propose a method for determining the agreement between model and reality quantitatively. To protect the manufacturer's intellectual property, we introduce a normalization method for presenting the results. For the studied stack, the apparent electrochemically active surface of the electrode is 41% larger than its geometrical area. Hence, the current density in the diffusion layer is 29% smaller than previously reported for a zero-dimensional model.

  15. Investigation on the fates of vanadium and nickel during co-gasification of petroleum coke with biomass.

    Science.gov (United States)

    Li, Jiazhou; Wang, Xiaoyu; Wang, Bing; Zhao, Jiantao; Fang, Yitian

    2018-06-01

    This study investigates the volatilization behaviors and mineral transformation of vanadium and nickel during co-gasification of petroleum coke with biomass. Moreover, the evolution of occurrence modes of vanadium and nickel was also determined by the method of sequential chemical extraction. The results show that the volatilities of vanadium and nickel in petroleum coke have a certain level of growth with an increase in the temperature. With the addition of biomass, their volatilities both show an obvious decrease. Organic matter and stable forms are the dominant chemical forms of vanadium and nickel. After gasification, organic-bound vanadium and nickel decompose completely and convert into other chemical forms. The crystalline phases of vanadium trioxide, coulsonite, nickel sulfide, and elemental nickel are clearly present in petroleum coke and biomass gasification ashes. When the addition of biomass reaches 60 wt%, the diffraction peaks of orthovanadate are found while that of vanadium trioxide disappear. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Osteogenic potential of bone marrow stromal cells on smooth, roughened, and tricalcium phosphate-modified titanium alloy surfaces.

    LENUS (Irish Health Repository)

    Colombo, John S

    2012-09-01

    This study investigated the influence of smooth, roughened, and tricalcium phosphate (TCP)-coated roughened titanium-aluminum-vanadium (Ti-6Al-4V) surfaces on the osteogenic potential of rat bone marrow stromal cells (BMSCs).

  17. Effects of vanadium on population growth and Na-K-ATPase activity of the brackish water hydroid Cordylophora caspia

    Energy Technology Data Exchange (ETDEWEB)

    Ringelband, U.; Karbe, L. [Institut fuer Hydrobiologie und Fischereiwissenschaft, Hamburg (Germany)

    1996-07-01

    Vanadium, a relatively abundant heavy metal, enters the environment naturally through rock weathering. A large fraction of vanadium input is of human origin. The combustion of petroleum- and coal-products, which contain relatively high concentrations of vanadium, is one of the most important sources of the enrichment of vanadium in the environment. As it is used as an alloy, and vanadium rich iron-ores of various origin are used in steel production, the residual slag-stones of the steel industry can contain considerable vanadium concentrations. Wherever slag-stones serve as a cheap and convenient material in riverbank reinforcement, vanadium can leach into the aquatic environment. Vanadium is regarded as an essential trace element for higher animals. Cantley et al. indicated a regulatory function of vanadate in vivo. Although considerable information is available on the toxic effects of vanadium on humans, very little is known about the toxicity of vanadium towards aquatic organisms, especially invertebrates. Bell and Sargent have shown an inhibition of Na-K-ATPase activity in gills of the eel Anguilla anguilla. Holleland and Towle have demonstrated the inhibition of Na-K-ATPase activity in the gills of the shore crab Carcinus maenas. The aim of this study was to determine the toxicity of vanadium towards the brackish water hydroid Cordylophora caspia. Hydroids are known to be particularly sensitive to heavy metals and their asexual reproduction can be used in a well-established population growth test. Furthermore, the effects of vanadium on Na-K-ATPase activity in hydroids were studied in in vivo experiments, wherein the animals were exposed to sublethal concentrations of vanadium. In addition, the inhibition of Na-K-ATPase was measured in vitro, by adding vanadium to a microsomal preparation. 16 refs., 4 figs.

  18. Temperature fluctuation effect on microstructural evolution of vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Hideo; Ochiai, Kenso; Yoshida, Naoaki [Kyushu Univ., Kasuga, Fukuoka (Japan). Research Inst. for Applied Mechanics

    1996-04-01

    To compare the damage structure of vanadium and it`s alloy by irradiation at a constant and fluctuating temperature, the microstructure of samples irradiated by heavy ion were observed by an electron microscope. Pure vanadium (99.9%) from China was used as samples. After preparing the samples for the electron microscope, they are covered with Zr and Ta film, vacuum sealed and annealed for 2h at 1323K. Then the samples were irradiated by 3 MeV Cu ion of 0.75-100 dpa at 473-873K. Temperature was changed from low to high (473K/673K, 473K/873K, 673K/873K). On the irradiation experiments at constant temperature, the density of dislocation decreased with increasing temperature, but, more than 773K, the density became very low and the needle precipitation grown to <100> and void were observed. On the irradiation experiment at 673K/873K, the density of number of precipitation and void were decreased. (S.Y.)

  19. Porphyrin doped vanadium pentoxide xerogel as electrode material

    Energy Technology Data Exchange (ETDEWEB)

    Anaissi, F.J.; Engelmann, F.M.; Araki, K.; Toma, H.E. [Sao Paulo Univ., SP (Brazil). Inst. de Quimica

    2003-04-01

    The lamellar composite material, VXG-TMPyP, obtained from the combination of cationic, water-soluble meso-(tetra-4-methyl-pyridinium)porphyrin (TMPyP) and vanadium pentoxide gel was investigated and employed as electrode modifying material. This material was isolated as a xerogel and characterized by X-ray diffraction, UV-Vis spectroscopy, cyclic voltammetry, spectro-electrochemistry and TG analysis. According to the X-ray diffraction data, the original VXG lamellar matrix framework is kept in the composite, evidencing a topotatic reaction. UV-Vis spectra indicated a strong interaction between VXG and TMPyP leading to the protonation of the porphyrin ring. In contrast with the vanadium oxide xerogel the new material is stable in water. The presence of the cationic porphyrin species in its structure turns it able to incorporate negatively charged ions, such as ferrocyanide and I{sup -}. The presence of the I{sub 2}/I{sup -} couple gives rise to a dramatic increase in the reversibility of the V{sup V/IV} process and in the charge capacity of the material. (authors)

  20. Dynamic recrystallization behavior of a medium carbon vanadium microalloyed steel

    International Nuclear Information System (INIS)

    Wei, Hai-lian; Liu, Guo-quan; Xiao, Xiang; Zhang, Ming-he

    2013-01-01

    The dynamic recrystallization behavior of a medium carbon vanadium microalloyed steel was systematically investigated at the temperatures from 900 °C to 1100 °C and strain rates from 0.01 s −1 to 10 s −1 on a Gleeble-1500 thermo-simulation machine. The flow stress constitutive equation of hot deformation for this steel was developed with the activation energy Q being about 273 kJ/mol, which is in reasonable agreement with those reported before. Activation energy analysis showed that vanadium addition in microalloyed steels seemed not to affect the activation energy much. The effect of Zener–Hollomon parameter on the characteristic points of flow curves was studied using the power law relation, and the dependence of critical strain (stress) on peak strain (stress) obeyed a linear equation. Dynamic recrystallization is the most important softening mechanism for the experimental steel during hot compression. The dynamic recrystallization kinetics model of this steel was established based on flow stress and a frequently-used dynamic recrystallization kinetics equation. Dynamic recrystallization microstructure under different deformation conditions was also observed and the dependence of steady-state grain size on the Zener–Hollomon parameter was plotted

  1. Kinetic spectrophotometric determination of trace amounts of selenium and vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Safavi, A.; Sedghy, H.R.; Shams, E. [Dept. of Chemistry, Shiraz Univ. (Iran)

    1999-11-01

    A sensitive kinetic spectrophotometric method has been developed for the determination of Se(IV) over the range of 45 to 4000 ng in 10 mL of solution. The method is based on the catalytic effect of Se(IV) on the reduction reaction of bromate by hydrazinium dichloride, with subsequent reaction of Ponceau S with products of the above reaction (chlorine and bromine), causing color changing of Ponceau S. Method development includes optimization of time interval for measurement of slope, pH, reagents concentration, and temperature. The optimized conditions yielded a theoretical detection limit of 33 ng/10 mL of solution of Se(IV). The interfering effects were studied and removed. The method was applied to the determination of selenium in spiked water, Kjeldahl tablet, selenium tablet, and shampoo. Vanadium(V) has an inhibition effect on the catalyzed reaction of bromate and hydrazine by selenium. Using this effect, V(V) can be determined in the range of 70 to 2500 ng in 10 mL of solution. The optimization procedure includes pH and selenium concentration. An extraction method was used for interference removal. The method was applied to the determination of vanadium in petroleum. (orig.)

  2. Mechanical and electrochemical characterization of vanadium nitride (VN) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Caicedo, J.C., E-mail: Jcesarca@calima.univalle.edu.co [Grupo de Peliculas Delgadas, Departamento de Fisica, Universidad del Valle, Cali (Colombia); Zambrano, G. [Grupo de Peliculas Delgadas, Departamento de Fisica, Universidad del Valle, Cali (Colombia); Aperador, W. [Ingenieria Mecatronica, Universidad Militar Nueva Granada, Bogota (Colombia); Escobar-Alarcon, L.; Camps, E. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico, DF 11801 (Mexico)

    2011-10-15

    Vanadium nitride (V-N) thin films were grown using a reactive d.c. magnetron sputtering process, from a vanadium target (99.999%) in an Ar/N{sub 2} gas mixture at different deposition bias voltage. Films were deposited onto silicon (1 0 0) and RUS-3 steel substrates at 400 deg. C. Structural, compositional, mechanical and electrochemical characterizations were performed by X-ray diffraction (XRD), elastic forward analysis (EFA), nanoindentation, electrochemical impedance spectroscopy (EIS), and Tafel polarization curves, respectively. X-ray diffraction patterns show the presence of (1 1 1) and (2 0 0) crystallographic orientations associated to the V-N cubic phase. Nanoindentation measurements revealed that when the bias voltage increases from 0 V to -150 V the hardness and elastic modulus are increased from 11 GPa to 20 GPa and from 187 GPa to 221 GPa, respectively. EIS and Tafel curves showed that the corrosion rate of steel, coated with V-N single layer films deposited without bias voltage, diminishes 90% compared to the steel without this coating. On the other hand, when the V-N coating was deposited at the highest d.c. bias voltage (-150 V), the corrosion rate was greater than in the steel coated with zero-voltage (0 V) V-N films. This last result could be attributed to the formation of porosities produced by the ion bombardment during the deposition process.

  3. Mechanical and electrochemical characterization of vanadium nitride (VN) thin films

    International Nuclear Information System (INIS)

    Caicedo, J.C.; Zambrano, G.; Aperador, W.; Escobar-Alarcon, L.; Camps, E.

    2011-01-01

    Vanadium nitride (V-N) thin films were grown using a reactive d.c. magnetron sputtering process, from a vanadium target (99.999%) in an Ar/N 2 gas mixture at different deposition bias voltage. Films were deposited onto silicon (1 0 0) and RUS-3 steel substrates at 400 deg. C. Structural, compositional, mechanical and electrochemical characterizations were performed by X-ray diffraction (XRD), elastic forward analysis (EFA), nanoindentation, electrochemical impedance spectroscopy (EIS), and Tafel polarization curves, respectively. X-ray diffraction patterns show the presence of (1 1 1) and (2 0 0) crystallographic orientations associated to the V-N cubic phase. Nanoindentation measurements revealed that when the bias voltage increases from 0 V to -150 V the hardness and elastic modulus are increased from 11 GPa to 20 GPa and from 187 GPa to 221 GPa, respectively. EIS and Tafel curves showed that the corrosion rate of steel, coated with V-N single layer films deposited without bias voltage, diminishes 90% compared to the steel without this coating. On the other hand, when the V-N coating was deposited at the highest d.c. bias voltage (-150 V), the corrosion rate was greater than in the steel coated with zero-voltage (0 V) V-N films. This last result could be attributed to the formation of porosities produced by the ion bombardment during the deposition process.

  4. Effect of vanadium and yttrium doping on BSCCO superconductors

    International Nuclear Information System (INIS)

    Mohamed, S.B.; Halim, S.A.; Azhan, H.; Sidek, H.A.A; Tee, T.W.; Hassan, Z.A.

    1999-01-01

    The effect of vanadium and yttrium doping on the superconductivity is investigated. The doping was done on the calcium site ranging from x=0.00-0.10. The temperature dependence of electrical resistance and AC susceptibility measurements were made on these samples. The zero resistance for vanadium doped samples varied from 107 K (x = 0.00) to 68.5K (x = 0.10), whereas for yttrium doped samples it varied from 107 K (x = 0.00) to 54K (x 0.10). The volume fraction of the 2223 phase for both dopalit decreases witli increasing doping concentration. The nature of the temperature derivative of the resistance curves indicates the presence of a superconducting transition between grains coupled by weak links. The AC susceptibility data show enrichment of the volume fraction of the low Tc phase at higher compositions. The presence of low Tc phase (∼70 K) is visible in the susceptibility data. X-ray diffraction confirms the presence of mixed phases in the samples. (author)

  5. Phase equilibria in the niobium-vanadium-hydrogen system

    Energy Technology Data Exchange (ETDEWEB)

    Bethin, J. (Grumman Aerospace Corp., Bethpage, NY (USA)); Welch, D.O. (Brookhaven National Lab., Upton, NY (USA)); Pick, M.A. (Commission of the European Communities, Abingdon (UK). JET Joint Undertaking)

    1990-01-01

    The effect of vanadium additions to niobium on the metal-hydrogen phase equilibria has been studied. Measurements of the equilibrium H{sub 2}(D{sub 2}) pressure-composition-temperature isotherms for Nb{sub 1-x}V{sub x} alloys with 0{le}x<0.2 were used to determine the depression of the {alpha} - {alpha}' critical temperature with increasing vanadium concentration. A simple lattice-fluid model guided reduction of the data. Changes in the triple point temperature as well as the shift of the {zeta} {yields} {epsilon} phase transition were determined by differential scanning calorimetry measurements. A rapid overall depression was found, of the order of 7 K (at.% substituted V){sup -1}, for the metal-hydrogen (deuterium) phase boundary structure when compared with the Nb-H system in the hydrogen concentration range of interest. The results explain the enhanced terminal solubility of hydrogen in this system found previously by other authors. The changes in the phase equilibria are discussed in terms of the effect of hydrogen trapping and compared with the results of a cluster-variation calculation for random-field systems of previous authors, taking into account a distribution of H-site energies due to alloying. (author).

  6. Vanadium alloys for the radiative divertor program of DIII-D

    International Nuclear Information System (INIS)

    Smith, J.P.; Johnson, W.R.; Stambaugh, R.D.; Trester, P.W.; Smith, D.; Bloom, E.

    1995-10-01

    Vanadium alloys provide an attractive solution for fusion power plants as they exhibit a potential for low environmental impact due to low level of activation from neutron fluence and a relatively short half-life. They also have attractive material properties for use in a reactor. General Atomics along with Argonne National Laboratory (ANL) and Oak Ridge National Laboratory (ORNL), has developed a plan to utilize vanadium alloys as part of the Radiative Divertor Project (RDP) modification for the DIII-D tokamak. The goal for using vanadium alloys is to provide a meaningful step towards developing advanced materials for fusion power applications by demonstrating the in-service behavior of a vanadium alloy (V-4Cr-4Ti) in a tokamak in conjunction with developing essential fabrication technology for the manufacture of full-scale vanadium alloy components. A phased approach towards utilizing vanadium in DIII-D is being used starting with small coupons and samples, advancing to a small component, and finally a portion of the new double-null, slotted divertor will be fabricated from vanadium alloy product forms. A major portion of the program is research and development to support fabrication and resolve key issues related to environmental effects

  7. Processing, characterization, and bactericidal activity of undoped and silver-doped vanadium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Tousley, M.E.; Wren, A.W.; Towler, M.R. [Inamori School of Engineering, Alfred University, Alfred, NY 14803 (United States); Mellott, N.P., E-mail: mellott@alfred.edu [Inamori School of Engineering, Alfred University, Alfred, NY 14803 (United States)

    2012-12-14

    Vanadium oxide (V) and silver-doped vanadium oxide (Ag-V) powders were prepared via sol-gel processing. Structural evolution and bactericidal activity was examined as a function of temperature ranging from 250, 350, 450 and 550 Degree-Sign C. Powders were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Raman spectroscopy. Results from all techniques showed vanadium pentoxide (V{sub 2}O{sub 5}) is the predominant phase regardless of heat treatment temperature or the addition of silver (Ag). XRD analysis suggests Ag is present as AgCl in samples heat treated to 250, 350, and 450 Degree-Sign C and as AgV{sub 6}O{sub 15} at 550 Degree-Sign C. Bactericidal activity was evaluated against Escherichia coli using the agar disk diffusion method considering both Ag-V and undoped, V powders. While the addition of Ag significantly increased bactericidal properties, the specific Ag valency, or crystal structure and morphology formed at higher temperatures, had little effect on functionality. -- Highlights: Black-Right-Pointing-Pointer Vanadium and silver-doped vanadium oxide powders were prepared via sol-gel. Black-Right-Pointing-Pointer Powders were characterized using advanced, complementary structural techniques. Black-Right-Pointing-Pointer Bactericidal activity was evaluated against E. coli. Black-Right-Pointing-Pointer Both vanadium and silver doped vanadium oxide show bactericidal activity.

  8. Vanadium in organic fossils as determined by nuclear-physical methods of analysis

    International Nuclear Information System (INIS)

    Nadirov, N.N.; Solodukhin, V.P.

    1998-01-01

    Results are presented of several year investigation to study possibilities of the NPMA for the determination of vanadium in organic fossils and applications of these methods to scientific and practical tasks. For these purposes, various versions of activation analysis (AA), X-ray fluorescence analysis (XRFA), electron spin resonance (ESR) spectroscopy and atomic emission with inductively coupled plasma spectroscopy (AES-ICP). Advantages and pitfalls of individual methods are discussed. The techniques developed can be used for estimation and calculation of stocks of vanadium in organic fossils at the territories of Kazakstan, Tatarstan and along the Volga-river. Analysis results helped in discovering new, industrially important deposits of this valuable metal. Quantitative determination of vanadium was carried out at different stages of technological processes of its extraction from high-viscous oils and oil-bitumen rocks. Results of analyses allowed to reveal the most effective versions of technologies of demetallization of these fossils. Content of vanadium was also studied in different locations of high-viscous oil deposits being explored by the method of inside-stratum burning. Results of analyses showed that the concentration of vanadium in oil decreases considerably with increasing temperature, that is, a considerable part of vanadium (up to 60 percent) may be lost irretrievably. Thus, for the exploration of these deposits a method of vapor-thermal influence onto the stratum was recommended, by using of which the loss of vanadium is insignificant

  9. A sensitive method for determining total vanadium in water samples using colorimetric-solid-phase extraction-fiber optic reflectance spectroscopy

    International Nuclear Information System (INIS)

    Filik, Hayati; Yanaz, Zeynep

    2009-01-01

    A selective colorimetric-solid-phase extraction (C-SPE) method for the determination of total vanadium in water samples was developed. This method introduced a new variation of C-SPE. The colour reaction is based on the reaction of vanadium(V) ternary complex formed with 1-(2-Pyridylazo)-2-naphtol (PAN) in the presence hydrogen peroxide (H 2 O 2 ). In this technique, the target analytes in samples are extracted onto solid matrix loaded with a colorimetric reagent and then quantified directly on the adsorbent surface by using a miniature fiber optic reflectance spectrometer. The measurements were carried out at a wavelength of 589.4 nm since it yielded the largest divergence different in reflectance spectra before and after reaction with the vanadium. The overall time required for the C-SPE procedure was ∼20 min. The amount of concentrated V is then determined in a few seconds by using miniature reflectance spectrometer. At the optimal conditions, a calibration curve was constructed, revealing a linear range of 0.05-0.52 mg L -1 and a detection limit as low as 0.01 mg L -1 while the RSD lower than 2.8%. In order to verify the accuracy of the method, a certified reference water samples (TMDA) were analysed and the results obtained were in good agreement with the certified values. The proposed method was applied to the determination of vanadium in tap water, seawater samples with a recovery for the spiked samples in the range of 98-102%.

  10. Vanadium-substituted heteropolyacids immobilized on amine- functionalized mesoporous MCM-41: A recyclable catalyst for selective oxidation of alcohols with H2O2

    International Nuclear Information System (INIS)

    Dong, Xinbo; Wang, Danjun; Li, Kebin; Zhen, Yanzhong; Hu, Huaiming; Xue, Ganglin

    2014-01-01

    Graphical abstract: Vanadium-substituted phosphotungstic acids are immobilized on amine- functionalized mesoporous MCM-41 and the hybrid catalyst is proved to be a highly efficient solid catalyst for the oxidation of aromatic alcohols to the corresponding carbonyl compounds with H 2 O 2 , featured by the high conversion and selectivity, easy recovery, and quite steady reuse. - Highlights: • Vanadium-substituted phosphotungstic acid immobilized on amine-functionalized mesoporous MCM-41 are prepared. • HPAs were fixed on the inner surface of mesoporous MCM-41 by chemical bonding to aminosilane groups. • The hybrid catalyst showed much higher catalytic activity than the pure HPAs. • The hybrid catalyst is a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols. - Abstract: New hybrid materials of vanadium-substituted phosphotungstic acids (VHPW) immobilized on amine-functionalized mesoporous MCM-41 (VHPW/MCM-41/NH 2 ) are prepared and characterized by FT-IR, XRD, N 2 adsorption, elemental analysis, SEM and TEM for their structural integrity and physicochemical properties. It is found that the structure of the heteropolyacids is retained upon immobilization over mesoporous materials. The catalytic activities of these hybrid materials are tested in the selective oxidation of alcohols to the carbonyl products with 30% aqueous H 2 O 2 as oxidant in toluene. The catalytic activities of different number of vanadium-substituted phosphotungstic acid are investigated, and among the catalysts, H 5 [PV 2 W 10 O 40 ] immobilized on amine-functionalized MCM-41 exhibits the highest activity with 97% conversion and 99% selectivity in the oxidation of benzyl alcohol to benzaldehyde. The hybrid catalyst is proved to be a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols to the corresponding aldehydes with H 2 O 2

  11. Vanadium-substituted heteropolyacids immobilized on amine- functionalized mesoporous MCM-41: A recyclable catalyst for selective oxidation of alcohols with H{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Xinbo [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Wang, Danjun [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); College of Chemistry Chemical Engineering, Yanan University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan' an 716000 (China); Li, Kebin [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Zhen, Yanzhong [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); College of Chemistry Chemical Engineering, Yanan University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan' an 716000 (China); Hu, Huaiming [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Xue, Ganglin, E-mail: xglin707@163.com [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China)

    2014-09-15

    Graphical abstract: Vanadium-substituted phosphotungstic acids are immobilized on amine- functionalized mesoporous MCM-41 and the hybrid catalyst is proved to be a highly efficient solid catalyst for the oxidation of aromatic alcohols to the corresponding carbonyl compounds with H{sub 2}O{sub 2}, featured by the high conversion and selectivity, easy recovery, and quite steady reuse. - Highlights: • Vanadium-substituted phosphotungstic acid immobilized on amine-functionalized mesoporous MCM-41 are prepared. • HPAs were fixed on the inner surface of mesoporous MCM-41 by chemical bonding to aminosilane groups. • The hybrid catalyst showed much higher catalytic activity than the pure HPAs. • The hybrid catalyst is a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols. - Abstract: New hybrid materials of vanadium-substituted phosphotungstic acids (VHPW) immobilized on amine-functionalized mesoporous MCM-41 (VHPW/MCM-41/NH{sub 2}) are prepared and characterized by FT-IR, XRD, N{sub 2} adsorption, elemental analysis, SEM and TEM for their structural integrity and physicochemical properties. It is found that the structure of the heteropolyacids is retained upon immobilization over mesoporous materials. The catalytic activities of these hybrid materials are tested in the selective oxidation of alcohols to the carbonyl products with 30% aqueous H{sub 2}O{sub 2} as oxidant in toluene. The catalytic activities of different number of vanadium-substituted phosphotungstic acid are investigated, and among the catalysts, H{sub 5}[PV{sub 2}W{sub 10}O{sub 40}] immobilized on amine-functionalized MCM-41 exhibits the highest activity with 97% conversion and 99% selectivity in the oxidation of benzyl alcohol to benzaldehyde. The hybrid catalyst is proved to be a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols to the corresponding aldehydes with H{sub 2}O{sub 2}.

  12. The fabrication and visible-near-infrared optical modulation of vanadium dioxide/silicon dioxide composite photonic crystal structure

    Science.gov (United States)

    Liang, Jiran; Li, Peng; Song, Xiaolong; Zhou, Liwei

    2017-12-01

    We demonstrated a visible and near-infrared light tunable photonic nanostructure, which is composed of vanadium dioxide (VO2) thin film and silicon dioxide (SiO2) ordered nanosphere arrays. The vanadium films were sputtered on two-dimensional (2D) SiO2 sphere arrays. VO2 thin films were prepared by rapid thermal annealing (RTA) method with different oxygen flow rates. The close-packed VO2 shell formed a continuous surface, the composition of VO2 films in the structure changed when the oxygen flow rates increased. The 2D VO2/SiO2 composite photonic crystal structure exhibited transmittance trough tunability and near-infrared (NIR) transmittance modulation. When the oxygen flow rate increased from 3 slpm to 4 slpm, the largest transmittance trough can be regulated from 904 to 929 nm at low temperature, the transmittance troughs also appear blue shift when the VO2 phase changes from insulator to metal. The composite nanostructure based on VO2 films showed visible transmittance tunability, which would provide insights into the glass color changing in smart windows.

  13. Polypyrrole-encapsulated vanadium pentoxide nanowires on a conductive substrate for electrode in aqueous rechargeable lithium battery.

    Science.gov (United States)

    Liang, Chaowei; Fang, Dong; Cao, Yunhe; Li, Guangzhong; Luo, Zhiping; Zhou, Qunhua; Xiong, Chuanxi; Xu, Weilin

    2015-02-01

    Precursors of ammonium vanadium bronze (NH4V4O10) nanowires assembled on a conductive substrate were prepared by a hydrothermal method. After calcination at 360°C, the NH4V4O10 precursor transformed to vanadium pentoxide (V2O5) nanowires, which presented a high initial capacity of 135.0mA h g(-1) at a current density of 50mA g(-1) in 5M LiNO3 aqueous solution; while the specific capacity faded quickly over 50 cycles. By coating the surface of V2O5 nanowires with water-insoluble polypyrrole (PPy), the formed nanocomposite electrode exhibited a specific discharge capacity of 89.9mA h g(-1) at 50mA g(-1) (after 100 cycles). A V2O5@PPy //LiMn2O4 rechargeable lithium battery exhibited an initial discharge capacity of 95.2mA h g(-1); and after 100 cycles, a specific discharge capacity of 81.5mA h g(-1) could retain at 100mA g(-1). Copyright © 2014 Elsevier Inc. All rights reserved.

  14. The fabrication and visible-near-infrared optical modulation of vanadium dioxide/silicon dioxide composite photonic crystal structure

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Jiran; Li, Peng; Song, Xiaolong; Zhou, Liwei [Tianjin University, School of Microelectronics, Tianjin (China)

    2017-12-15

    We demonstrated a visible and near-infrared light tunable photonic nanostructure, which is composed of vanadium dioxide (VO{sub 2}) thin film and silicon dioxide (SiO{sub 2}) ordered nanosphere arrays. The vanadium films were sputtered on two-dimensional (2D) SiO{sub 2} sphere arrays. VO{sub 2} thin films were prepared by rapid thermal annealing (RTA) method with different oxygen flow rates. The close-packed VO{sub 2} shell formed a continuous surface, the composition of VO{sub 2} films in the structure changed when the oxygen flow rates increased. The 2D VO{sub 2}/SiO{sub 2} composite photonic crystal structure exhibited transmittance trough tunability and near-infrared (NIR) transmittance modulation. When the oxygen flow rate increased from 3 slpm to 4 slpm, the largest transmittance trough can be regulated from 904 to 929 nm at low temperature, the transmittance troughs also appear blue shift when the VO{sub 2} phase changes from insulator to metal. The composite nanostructure based on VO{sub 2} films showed visible transmittance tunability, which would provide insights into the glass color changing in smart windows. (orig.)

  15. Effect of L-glutamic acid on the positive electrolyte for all-vanadium redox flow battery

    International Nuclear Information System (INIS)

    Liang, Xinxing; Peng, Sui; Lei, Ying; Gao, Chao; Wang, Nanfang; Liu, Suqin; Fang, Dong

    2013-01-01

    Highlights: ► Amino acid is used as additive for all-vanadium redox flow battery. ► The additive can significantly improve performance of positive electrolyte. ► Mechanism for the improvement is investigated. -- Abstract: L-Glutamic acid is used as an additive for the positive electrolyte of all-vanadium redox flow battery (VRFB), and its effect on the thermal stability and electrochemical activity is investigated. It is found that the addition of L-glutamic can significantly alleviate the precipitation of V 2 O 5 from positive electrolyte. The conservation rate of V(V) ion can be as high as 58% after 2 M V(V) solution being kept in 40 °C for 89 h. Besides, L-glutamic can also improve the mass transport and electrochemical performance of anolyte. A high coulombic efficiency of over 95% and energy efficiency of 74% are obtained. XPS spectra illustrate that L-glutamic can react with the surface of carbon felt electrode and introduce more oxygen-containing and nitrogen-containing groups, which should be responsible for the improvement of electrochemical performance

  16. Some Ternary Phenylmethoxybis(tetrazolium) Complexes of Vanadium(IV,V) and Their Constants of Association

    OpenAIRE

    Gavazov, Kiril Blazhev; Racheva, Petya Vasileva; Lekova, Vanya Dimitrova; Dimitrov, Atanas Nikolov; Türkyilmaz, Murat; Genç, Fatma

    2012-01-01

    Several liquid-liquid extraction systems containing vanadium {vanadium(IV) or vanadium(V)}, azoderivative of resorcinol {ADR: 4-(2-pyridylazo)-resorcinol (PAR) or 4-(2-thiazolylazo)-resorcinol (TAR)} and (phenylmethoxibis)tetrazolium salts {MBT: 3,3'-(3,3'-dimetoxy-4,4'-biphenylene)-bis(2,5-diphenyl-2H-tetrazolium) chloride (Blue Tetrazolium, BT) or 3,3'-(3,3'-dimetoxy-4,4'-biphenylene)-bis[2,5-di(4-nitrophenyl)-2H-tetrazolium] chloride (Tetranitroblue Tetrazolium, TNBT)} were studied. The op...

  17. The use of vanadium as a scattering standard for pulsed source neutron spectrometers

    International Nuclear Information System (INIS)

    Mayers, J.

    1983-06-01

    The Gaussian approximation for multiphonon cross-sections has been used in a calculation of the variation of vanadium cross-sections with incident neutron energy. The results show that vanadium behaves as an elastic scatterer to within a few percent on pulsed neutron spectrometers with incident neutron energies up to 1 eV. There is a calculated anisotropy in the scattering of 8%. It is found that the scattering properties of vanadium at 77K and 293K differ by a maximum of 1% except for neutron energies < 15 meV. (author)

  18. Distributions of traces of metals on sorption from solutions of vanadium(V)

    International Nuclear Information System (INIS)

    Evseeva, N.K.; Turnaov, A.N.; Telegin, G.F.; Kremenskaya, I.N.

    1983-01-01

    A study is made of the distributions of traces of metals between aqueous solutions of vanadium(V) and a solid reagent made by introducing di-2-ethylhexylphosphoric acid into an inert matrix: a nonionic macroporous copolymer of polystyrene with divinyl benzene (wofatit Y 29). As regards degree of extraction, the trace components fall in the series zinc > cadmium > manganese > copper > cobalt, which resemble the extractability series. The vanadium content of the solution and the concentrations of the trace components have virtually no effect on the sorption. The process is effective in concentrating trace components from solutions containing vanadium(V)

  19. Distribution of microimpurities of metals at their sorption from vanadium (5) solutions

    International Nuclear Information System (INIS)

    Evseeva, N.K.; Turanov, A.N.; Telegin, G.F.; Kremenskaya, I.N.

    1983-01-01

    Distribution of metal microimpurities (Zn, Mn, Cu, Co, Fe) between aqueous solutions of vanadium (5) and solid extracting agent, prepared by means of introduction of di-2-ethylhexylphosphoric acid into inert matrix-nonionogeneous macropore copolymer of polystyrene with divinylbenzene (vofatit Y-29), has been studied. Accroding to the degree of extraction the microimpurities are arranged in the series: zinc > cadmium > manganese > copper > cobalt, which is similar to the series of extractability. Vanadium content in solution and concentration of microimpurities practically does not affect the sorption. It has been established that the process is effective for microimpurities concentration from solutions containing vanadium (5)

  20. Distribution of microimpurities of metals at their sorption from vanadium (5) solutions

    Energy Technology Data Exchange (ETDEWEB)

    Evseeva, N.K.; Turanov, A.N.; Telegin, G.F.; Kremenskaya, I.N.

    1983-01-01

    Distribution of metal microimpurities (Zn, Mn, Cu, Co, Fe) between aqueous solutions of vanadium (5) and solid extracting agent, prepared by means of introduction of di-2-ethylhexylphosphoric acid into inert matrix-nonionogeneous macropore copolymer of polystyrene with divinylbenzene (vofatit Y-29), has been studied. According to the degree of extraction the microimpurities are arranged in the series: zinc > cadmium > manganese > copper > cobalt, which is similar to the series of extractability. Vanadium content in solution and concentration of microimpurities practically does not affect the sorption. It has been established that the process is effective for microimpurities concentration from solutions containing vanadium (5).

  1. Magnetic and luminescent properties of vanadium-doped ZnSe crystals

    Energy Technology Data Exchange (ETDEWEB)

    Radevici, Ivan, E-mail: ivarad@utu.fi [Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., MD-2009 Chisinau (Moldova, Republic of); Nedeoglo, Natalia; Sushkevich, Konstantin [Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., MD-2009 Chisinau (Moldova, Republic of); Huhtinen, Hannu [Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Nedeoglo, Dmitrii [Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., MD-2009 Chisinau (Moldova, Republic of); Paturi, Petriina [Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland)

    2016-12-15

    Magnetic and photoluminescence properties of vanadium-doped ZnSe crystals with impurity concentrations varied by changing the V amount in the source material from 0.03 to 0.30 at% are studied in 5–300 K temperature range. Investigation of magnetic properties shows that the studied concentrations of vanadium impurity that should not disturb crystal lattice are insignificant for observing ferromagnetic behaviour even at low temperatures. The contribution of V impurity to edge emission and its influence on infra-red emission are discussed. Similarities of magnetic and luminescent properties induced by vanadium and other transition metal impurities are discussed.

  2. Rutile vanadium antimonates. A new class of catalysts for selective reduction of NO with ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Brazdil, James F.; Ebner, Ann M.; Cavalcanti, Fernando A.P. [BP Chemicals Inc., Cleveland, OH (United States)

    1997-12-31

    This paper describes a new class of vanadium containing oxide catalysts that are active and selective for the selective catalytic reduction of NO with ammonia. Vanadium antimony oxide based catalysts were found to be effective in the conversion of NO with little or no ammonia slippage when tested using gas mixtures containing between 300 and 700ppm NO. X-ray diffraction analyses of the catalysts show that the dominant phase present in the catalyst is vanadium antimonate having a defect rutile crystal structure. The catalysts are active and selective in the ranges of 400-460C and gas hourly space velocities of 3000-8000h{sup -1}

  3. On change of vanadium carbide state during 20Kh3MVF steel heat treatment

    International Nuclear Information System (INIS)

    Gitgarts, M.I.; Maksimenko, V.N.

    1975-01-01

    The Xray diffraction study of vanadium carbide MC has been made in the steel-20KH3MVF quenched from 970 and 1040 deg and tempered at 660 deg for 210 hrs. It has been found that the constant of the MC crystal lattice regularly varies with the temperature of isothermal hold-up. In the steel tempered after quenching two vanadium carbides of different content could co-exist simultaneously: carbide formed in the quenching process and carbide formed during tempering. The discovered effect of the temperature dependence of the MC content is, evidently, inherent also to other steels containing vanadium

  4. Test of vanadium pentoxide as anode for the electrooxidation of toluene

    Energy Technology Data Exchange (ETDEWEB)

    D' Elia, L.F. [Petroleos de Venezuela - Intevep, Caracas (Venezuela). Departamento de Tecnologias Emergentes; Rincon, L.; Ortiz, R. [Universidad de los Andes, Merida (Venezuela). Departamento de Quimica

    2004-11-15

    Vanadium pentoxide (V{sub 2}O{sub 5}) films were prepared by electrochemical and thermal decomposition of vanadyl sulphate on titanium dioxide covered titanium plates and glassy carbon discs. The prepared material by thermal decomposition showed high surface area and good physical stability; while the electrodeposited films, although being homogeneous, showed poor adhesion. The V{sub 2}O{sub 5} electrodes were chemically and electrochemically stable in aqueous (1 M H{sub 2}SO{sub 4} + 1 M NaOH, pH 3) and organic (0.1 M But{sub 4}NPF{sub 6} + CH{sub 3}CN) solutions. In both cases, a well defined electrochemical response was observed. At the experimental conditions, the prepared materials were not active for the electrooxidation of toluene. The theoretical modeling suggests that the lack of activity is due to the weak interaction between toluene and the V{sub 2} O{sub 5} surface. (author)

  5. Test of vanadium pentoxide as anode for the electrooxidation of toluene

    Energy Technology Data Exchange (ETDEWEB)

    D' Elia, Luis F. [Petroleos de Venezuela (PDVSA)-Intevep, Departamento de Tecnologias Emergentes, Apartado 76343, Caracas 1070-A (Venezuela)]. E-mail: delialf@pdvsa.com; Rincon, L. [Universidad de los Andes, Facultad de Ciencias, Departamento de Quimica, Grupo de Quimica Teorica, Merida 5101 (Venezuela); Ortiz, R. [Universidad de los Andes, Facultad de Ciencias, Departamento de Quimica, Laboratorio de Electroquimica, Merida 5101 (Venezuela)

    2004-11-15

    Vanadium pentoxide (V{sub 2}O{sub 5}) films were prepared by electrochemical and thermal decomposition of vanadyl sulphate on titanium dioxide covered titanium plates and glassy carbon discs. The prepared material by thermal decomposition showed high surface area and good physical stability; while the electrodeposited films, although being homogeneous, showed poor adhesion. The V{sub 2}O{sub 5} electrodes were chemically and electrochemically stable in aqueous (1 M H{sub 2}SO{sub 4} + 1 M NaOH, pH 3) and organic (0.1 M But{sub 4}NPF{sub 6} + CH{sub 3}CN) solutions. In both cases, a well defined electrochemical response was observed. At the experimental conditions, the prepared materials were not active for the electrooxidation of toluene. The theoretical modeling suggests that the lack of activity is due to the weak interaction between toluene and the V{sub 2}O{sub 5} surface.

  6. Electrochemical performance of polypyrrole/silver vanadium oxide composite cathodes in lithium primary batteries

    Science.gov (United States)

    Anguchamy, Yogesh K.; Lee, Jong-Won; Popov, Branko N.

    Polypyrrole (PPy)/silver vanadium oxide (SVO) composite cathode materials were synthesized by polymerizing pyrrole onto the surface of pure SVO particles. Electrochemical characterization was carried out by performing galvanostatic discharge, pulse discharge and ac-impedance experiments. The composite electrode exhibited better performance than pristine SVO in all the experiments. The composite electrodes yielded a higher discharge capacity and a better pulse discharge capability when compared to the pristine SVO electrode. The pulse discharge and ac-impedance studies indicated that PPy forms an effective conductive network on the SVO surface and thereby reduces the particle-to-particle contact resistance and facilitates the interfacial charge transfer kinetics. To determine the thermal stability of the composite cathode, galvanostatic discharge and ac-impedance experiments were performed at different temperatures. The capacity increased with temperature due to enhanced charge transfer kinetics and low mass transfer limitations. The peak capacity was obtained at 60 °C, after which the performance degraded with any further increase in temperature.

  7. Electrochemical performance of polypyrrole/silver vanadium oxide composite cathodes in lithium primary batteries

    Energy Technology Data Exchange (ETDEWEB)

    Anguchamy, Yogesh K.; Lee, Jong-Won; Popov, Branko N. [Center for Electrochemical Engineering, Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

    2008-09-15

    Polypyrrole (PPy)/silver vanadium oxide (SVO) composite cathode materials were synthesized by polymerizing pyrrole onto the surface of pure SVO particles. Electrochemical characterization was carried out by performing galvanostatic discharge, pulse discharge and ac-impedance experiments. The composite electrode exhibited better performance than pristine SVO in all the experiments. The composite electrodes yielded a higher discharge capacity and a better pulse discharge capability when compared to the pristine SVO electrode. The pulse discharge and ac-impedance studies indicated that PPy forms an effective conductive network on the SVO surface and thereby reduces the particle-to-particle contact resistance and facilitates the interfacial charge transfer kinetics. To determine the thermal stability of the composite cathode, galvanostatic discharge and ac-impedance experiments were performed at different temperatures. The capacity increased with temperature due to enhanced charge transfer kinetics and low mass transfer limitations. The peak capacity was obtained at 60 C, after which the performance degraded with any further increase in temperature. (author)

  8. Phase formation at bonded vanadium and stainless steel interfaces

    International Nuclear Information System (INIS)

    Summers, T.S.E.

    1992-01-01

    The interface between vanadium bonded to stainless steel was studies to determine whether a brittle phase formed during three joining operations. Inertia friction welds between V and 21-6-9 stainless steel were examined using TEM. In the as-welded condition, a continuous, polygranular intermetallic layer about 0.25 μm thick was present at the interface. This layer grew to about 50 μm thick during heat treatment at 1000 degrees C for two hours. Analysis of electron diffraction patterns confirmed that this intermetallic was the ω phase. The interface between vanadium and type 304, SANDVIK SAF 2205, and 21-6-9 stainless steel bonded by a co-extrusion process had intermetallic particles at the interface in the as-extruded condition. Heat treatment at 1000 degrees C for two hours caused these particles to grow into continuous layers in all three cases. Based on the appearance, composition and hardness of this interfacial intermetallic, it was also concluded to be ω phase. Bonding V to type 430 stainless steel by co-extrusion caused V-rich carbides to form at the interface due to the higher concentration of C in the type 430 than in the other stainless steels investigated. The carbide particles initially present grew into a continuous layer during a two-hour heat treatment at 1000 degrees C. Co-hipping 21-6-9 stainless steel tubing with V rod resulted in slightly more concentric specimens than the co-extruded ones, but a continuous layer of the ω phase formed during the hipping operation. This brittle layer could initiate failure during subsequent forming operations. The vanadium near the stainless steel interface in the co-extruded and co-hipped tubing in some cases was harder than before heat treatment. It was concluded that this hardening was due to thermal straining during cooling following heat treatment and that thermal strains might present a greater problem than seen here when longer tubes are used in actual applications

  9. First-principles study of adsorption-desorption kinetics of aqueous V2+/V3+ redox species on graphite in a vanadium redox flow battery.

    Science.gov (United States)

    Jiang, Zhen; Klyukin, Konstantin; Alexandrov, Vitaly

    2017-06-14

    Vanadium redox flow batteries (VRFBs) represent a promising solution to grid-scale energy storage, and understanding the reactivity of electrode materials is crucial for improving the power density of VRFBs. However, atomistic details about the interactions between vanadium ions and electrode surfaces in aqueous electrolytes are still lacking. Here, we examine the reactivity of the basal (0001) and edge (112[combining macron]0) graphite facets with water and aqueous V 2+ /V 3+ redox species at 300 K employing Car-Parrinello molecular dynamics (CPMD) coupled with metadynamics simulations. The results suggest that the edge surface is characterized by the formation of ketonic C[double bond, length as m-dash]O functional groups due to complete water dissociation into the H/O/H configuration with surface O atoms serving as active sites for adsorption of V 2+ /V 3+ species. The formation of V-O bonds at the surface should significantly improve the kinetics of electron transfer at the edge sites, which is not the case for the basal surface, in agreement with the experimentally hypothesized mechanism.

  10. A Disposable Alkaline Phosphatase-Based Biosensor for Vanadium Chronoamperometric Determination

    Directory of Open Access Journals (Sweden)

    Ana Lorena Alvarado-Gámez

    2014-02-01

    Full Text Available A chronoamperometric method for vanadium ion determination, based on the inhibition of the enzyme alkaline phosphatase, is reported. Screen-printed carbon electrodes modified with gold nanoparticles were used as transducers for the immobilization of the enzyme. The enzymatic activity over 4-nitrophenyl phosphate sodium salt is affected by vanadium ions, which results in a decrease in the chronoamperometric current registered. The developed method has a detection limit of 0.39 ± 0.06 µM, a repeatability of 7.7% (n = 4 and a reproducibility of 8% (n = 3. A study of the possible interferences shows that the presence of Mo(VI, Cr(III, Ca(II and W(VI, may affect vanadium determination at concentration higher than 1.0 mM. The method was successfully applied to the determination of vanadium in spiked tap water.

  11. Development of vanadium base alloys for fusion first-wall/blanket applications

    International Nuclear Information System (INIS)

    Smith, D.L.; Chung, H.M.; Loomis, B.A.; Matsui, H.; Votinov, S.; VanWitzenburg, W.

    1994-01-01

    Vanadium alloys have been identified as a leading candidate material for fusion first-wall/blanket applications. Certain vanadium alloys exhibit favorable safety and environmental characteristics, good fabricability, high temperature and heat load capability, good compatibility with liquid metals and resistance to irradiation damage effects. The current focus is on vanadium alloys with (3-5)% Cr and (3-5)% Ti with a V-4Cr-4Ti alloy as the leading candidate. Preliminary results indicate that the crack-growth rates of certain alloys are not highly sensitive to irradiation. Results from the Dynamic Helium Charging Experiment (DHCE) which simulates fusion relevant helium/dpa ratios are similar to results from neutron irradiated material. This paper presents an overview of the recent results on the development of vanadium alloys for fusion first wall/blanket applications

  12. LPTR irradiation of LLL vanadium tensile specimens and LLL Nb--1Zr tensile specimens

    International Nuclear Information System (INIS)

    MacLean, S.C.; Rowe, C.L.

    1977-01-01

    The LPTR irradiation of 14 LLL vanadium tensile specimens and 14 LLL Nb-1Zr tensile specimens is described. Sample packaging, the irradiation schedule and neutron fluences for three energy ranges are given

  13. Vanadium oxide V2O5 reaction with calcium metavanadate

    International Nuclear Information System (INIS)

    Krasnenko, T.I.; Slobodin, B.V.; Zhilyaev, V.A.

    1983-01-01

    Complex physicochemical studies on the V 2 O 5 Ca(VO 3 ) 2 mixtures, annealed under different conditions, were conducted. It was established that the V 2 O 5 -Ca(VO 3 ) 2 system is characterized by the following features: defective structure of initial components, which are in equilibrium state; irreversible structural transformation without changes in the macrosymmetry (530 deg C) of calcium metavanadate, deficient in calcium and oxygen; melting of eutectic mixture of components which are in equilibrium at 616+-3 deg C; Ca(VO 3 ) 2 melting with decomposition at 775+-3 deg C. Besides this, the formation of oxide vanadium bronze of β-type calcium is possible under some conditions (narrow temperature range, certain partial oxygen pressure, etc)

  14. Molecular dynamics simulation of deformation twin in rocksalt vanadium nitride

    International Nuclear Information System (INIS)

    Fu, Tao; Peng, Xianghe; Zhao, Yinbo; Li, Tengfei; Li, Qibin; Wang, Zhongchang

    2016-01-01

    We perform molecular dynamics simulation of nano-indentation with a cylindrical indenter to investigate the formation mechanism of deformation twin in vanadium nitride (VN) with a rocksalt structure. We find that the deformation twins occur during the loading stage, and subsequently conduct a systematic analysis of nucleation, propagation and thickening of a deformation twin. We find that the nucleation of a partial dislocation and its propagation to form a stacking fault are premise of deformation twin formation. The sequential nucleation and propagation of partial dislocation on adjacent parallel {111} planes are found to cause the thickening of the deformation twin. Moreover, the deformation twins can exist in VN at room temperature. - Highlights: • MD simulations of indentation are performed to study the deformation twin in VN. • The deformation twins can occur in VN during the loading stage. • The nucleation, propagation and thickening of a deformation twin are analyzed. • The deformation twins can exist in VN at room temperature.

  15. Neural Network Predictive Control for Vanadium Redox Flow Battery

    Directory of Open Access Journals (Sweden)

    Hai-Feng Shen

    2013-01-01

    Full Text Available The vanadium redox flow battery (VRB is a nonlinear system with unknown dynamics and disturbances. The flowrate of the electrolyte is an important control mechanism in the operation of a VRB system. Too low or too high flowrate is unfavorable for the safety and performance of VRB. This paper presents a neural network predictive control scheme to enhance the overall performance of the battery. A radial basis function (RBF network is employed to approximate the dynamics of the VRB system. The genetic algorithm (GA is used to obtain the optimum initial values of the RBF network parameters. The gradient descent algorithm is used to optimize the objective function of the predictive controller. Compared with the constant flowrate, the simulation results show that the flowrate optimized by neural network predictive controller can increase the power delivered by the battery during the discharge and decrease the power consumed during the charge.

  16. The trapping of hydrogen ions in vanadium and titanium

    International Nuclear Information System (INIS)

    Arbuzov, V.L.; Vykhodets, V.B.; Raspopova, G.A.

    1996-01-01

    The accumulation of implanted deuterium has been investigated at room temperature in vanadium, titanium and their alloys up to (2-15) x 10 17 ions cm -2 fluences by means of D(d,p)T reaction. The amount of accumulated D was measured using a 700 KeV D + ion beam during implantation. It is found that concentration of implanted deuterium in irradiated samples nonmonotonously increases with increasing fluence and in a complicated manner depends upon V-Ti alloy composition. These data are explained by concentration dependence of D diffusion coefficient in V-Ti alloys, structural ion irradiation induced inhomogeneity of alloys with >5-8 at.% Ti, and irradiation-enhanced diffusion of deuterium. (orig.)

  17. Highly repeatable nanoscale phase coexistence in vanadium dioxide films

    Science.gov (United States)

    Huffman, T. J.; Lahneman, D. J.; Wang, S. L.; Slusar, T.; Kim, Bong-Jun; Kim, Hyun-Tak; Qazilbash, M. M.

    2018-02-01

    It is generally believed that in first-order phase transitions in materials with imperfections, the formation of phase domains must be affected to some extent by stochastic (probabilistic) processes. The stochasticity would lead to unreliable performance in nanoscale devices that have the potential to exploit the transformation of physical properties in a phase transition. Here we show that stochasticity at nanometer length scales is completely suppressed in the thermally driven metal-insulator transition (MIT) in sputtered vanadium dioxide (V O2 ) films. The nucleation and growth of domain patterns of metallic and insulating phases occur in a strikingly reproducible way. The completely deterministic nature of domain formation and growth in films with imperfections is a fundamental and unexpected finding about the kinetics of this material. Moreover, it opens the door for realizing reliable nanoscale devices based on the MIT in V O2 and similar phase-change materials.

  18. Optical modulation in silicon-vanadium dioxide photonic structures

    Science.gov (United States)

    Miller, Kevin J.; Hallman, Kent A.; Haglund, Richard F.; Weiss, Sharon M.

    2017-08-01

    All-optical modulators are likely to play an important role in future chip-scale information processing systems. In this work, through simulations, we investigate the potential of a recently reported vanadium dioxide (VO2) embedded silicon waveguide structure for ultrafast all-optical signal modulation. With a VO2 length of only 200 nm, finite-differencetime- domain simulations suggest broadband (200 nm) operation with a modulation greater than 12 dB and an insertion loss of less than 3 dB. Predicted performance metrics, including modulation speed, modulation depth, optical bandwidth, insertion loss, device footprint, and energy consumption of the proposed Si-VO2 all-optical modulator are benchmarked against those of current state-of-the-art all-optical modulators with in-plane optical excitation.

  19. Decomposition of peracetic acid catalyzed by vanadium complexes

    International Nuclear Information System (INIS)

    Makarov, A.P.; Gekhman, A.E.; Moiseev, I.I.; Polotryuk, O.Y.

    1986-01-01

    This paper studies the decomposition of peracetic acid (AcOOH) in acetic acid (AcOH) catalyzed by vanadium complexes. It is shown that peractic acid in acetic acid solutions of ammonium anadate decomposes with the predominant formation of 0 2 and small amounts of CO 2 , the yield of which increases with increasing temperature and peracetic acid concentration. Both reactions proceed without the formation of free radicals in amounts detectable by ESR spectroscopy. The rate of oxygen release under conditions in which the formation of CO 2 is insignificant obeys a kinetic equation indicating the intermediate formation of a complex between V 5+ ions and peracetic acid and the slow conversion of this complex into the observed products

  20. Insulating Coating Development for Vanadium Alloys. Phase I Technical Report

    International Nuclear Information System (INIS)

    Gunda, N.; Sastri, S.; Jayaraman, M.; Karandikar, P.

    2000-01-01

    Self-cooled liquid-lithium/vanadium blanket offers many advantages for fusion power systems. Liquid metals moving through a magnetic field are subjected to magnetohydrodynamic (MHD) effects that can increase the pressure drop and affect the flow profiles and heat transfer. Insulating coatings are required to eliminate this effect. Based on the thermodynamic stability data five different coatings were selected PVD and CVD processes were developed to deposit these coatings. All coatings have resistivities much higher than the minimum required. Liquid lithium testing at Argonne National Laboratory indicates that one of the coatings showed only partial spalling. Thus, further refinement of this coating has significant potential to satisfy the requirements for Li/V blanket technology

  1. Simulation of vanadium-48 production using MCNPX code

    Directory of Open Access Journals (Sweden)

    Sadeghi Mahdi

    2012-01-01

    Full Text Available Vanadium-48 was produced through the irradiation of the natural titanium target via the natTi(p, xn48V reaction. The titanium target was irradiated at 1 mA current and by a 21 MeV proton beam for 4 hours. In this paper, the activity of 48V, 43Sc, and 46Sc radionuclides and the efficacy of the 47Ti(p, g, 48Ti(p, n, and 49Ti(p, 2n channel reactions to form 48V radionuclide were determined using MCNPX code. Furthermore, the experimental activity of 48V was compared with the estimated value for the thick target yield produced in the irradiation time according to MCNPX code. Good agreement between production yield of the 48V and the simulation yield was observed. In conclusion, MCNPX code can be used for the estimation of the production yield.

  2. Experimental investigation of radiative thermal rectifier using vanadium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Kota, E-mail: kotaito@mosk.tytlabs.co.jp [Toyota Central Research and Development Labs, Nagakute, Aichi 480-1192 (Japan); Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Nishikawa, Kazutaka; Iizuka, Hideo [Toyota Central Research and Development Labs, Nagakute, Aichi 480-1192 (Japan); Toshiyoshi, Hiroshi [Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8904 (Japan)

    2014-12-22

    Vanadium dioxide (VO{sub 2}) exhibits a phase-change behavior from the insulating state to the metallic state around 340 K. By using this effect, we experimentally demonstrate a radiative thermal rectifier in the far-field regime with a thin film VO{sub 2} deposited on the silicon wafer. A rectification contrast ratio as large as two is accurately obtained by utilizing a one-dimensional steady-state heat flux measurement system. We develop a theoretical model of the thermal rectifier with optical responses of the materials retrieved from the measured mid-infrared reflection spectra, which is cross-checked with experimentally measured heat flux. Furthermore, we tune the operating temperatures by doping the VO{sub 2} film with tungsten (W). These results open up prospects in the fields of thermal management and thermal information processing.

  3. Towards thiol functionalization of vanadium pentoxide nanotubes using gold nanoparticles

    International Nuclear Information System (INIS)

    Lavayen, V.; O'Dwyer, C.; Cardenas, G.; Gonzalez, G.; Sotomayor Torres, C.M.

    2007-01-01

    Template-directed synthesis is a promising route to realize vanadate-based 1-D nanostructures, an example of which is the formation of vanadium pentoxide nanotubes and associated nanostructures. In this work, we report the interchange of long-chained alkyl amines with alkyl thiols. This reaction was followed using gold nanoparticles prepared by the Chemical Liquid Deposition (CLD) method with an average diameter of ∼0.9nm and a stability of ∼85 days. V 2 O 5 nanotubes (VOx-NTs) with lengths of ∼2μm and internal hollow diameters of 20-100nm were synthesized and functionalized in a Au-acetone colloid with a nominal concentration of ∼4x10 -3 mol dm -3 . The interchange reaction with dodecylamine is found only to occur in polar solvents and incorporation of the gold nanoparticles is not observed in the presence of n-decane

  4. Study of structural changes during deformation of polycrystal vanadium

    International Nuclear Information System (INIS)

    Zubets, Yu.E.; Manilov, V.A.; Sarzhan, G.F.; Trefilov, V.I.; Firstov, S.A.

    1978-01-01

    Investigated were the polycrystalline vanadium dislocation structure formed within the range of temperatures between 20 and 1000 deg C and in the interval of deformations between 5 and 94%. The diagram of states was established in the temperature vs. degree of deformation coordinates from electron microscopy data. It was shown that a deformation of 5-7% leads to the appearance in the structure of incorrect shape dislocations with a lot of jogs and kinks. The density of relatively homogeneously distributed dislocations increases with the degree of deformation up to the latter's value of 50%. At a deformation greater than 50%, there forms a cellular structure, there remaining ranges where no cellular structure is formed. Thus, there appears a two-component texture with a different level of internal stresses. Annealing of such a material gives rise to areas of different types of cellular structure

  5. Electron-beam deposition of vanadium dioxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Marvel, R.E.; Appavoo, K. [Vanderbilt University, Interdisciplinary Materials Science Program, Nashville, TN (United States); Choi, B.K. [Vanderbilt University, Department of Electrical Engineering and Computer Science, Nashville, TN (United States); Nag, J. [Vanderbilt University, Department of Physics and Astronomy, Nashville, TN (United States); Haglund, R.F. [Vanderbilt University, Interdisciplinary Materials Science Program, Nashville, TN (United States); Vanderbilt University, Institute for Nanoscale Science and Engineering, Nashville, TN (United States); Vanderbilt University, Department of Physics and Astronomy, Nashville, TN (United States)

    2013-06-15

    Developing a reliable and efficient fabrication method for phase-transition thin-film technology is critical for electronic and photonic applications. We demonstrate a novel method for fabricating polycrystalline, switchable vanadium dioxide thin films on glass and silicon substrates and show that the optical switching contrast is not strongly affected by post-processing annealing times. The method relies on electron-beam evaporation of a nominally stoichiometric powder, followed by fast annealing. As a result of the short annealing procedure we demonstrate that films deposited on silicon substrates appear to be smoother, in comparison to pulsed laser deposition and sputtering. However, optical performance of e-beam evaporated film on silicon is affected by annealing time, in contrast to glass. (orig.)

  6. Determining the Limiting Current Density of Vanadium Redox Flow Batteries

    Directory of Open Access Journals (Sweden)

    Jen-Yu Chen

    2014-09-01

    Full Text Available All-vanadium redox flow batteries (VRFBs are used as energy storage systems for intermittent renewable power sources. The performance of VRFBs depends on materials of key components and operating conditions, such as current density, electrolyte flow rate and electrolyte composition. Mass transfer overpotential is affected by the electrolyte flow rate and electrolyte composition, which is related to the limiting current density. In order to investigate the effect of operating conditions on mass transport overpotential, this study established a relationship between the limiting current density and operating conditions. First, electrolyte solutions with different states of charge were prepared and used for a single cell to obtain discharging polarization curves under various operating conditions. The experimental results were then analyzed and are discussed in this paper. Finally, this paper proposes a limiting current density as a function of operating conditions. The result helps predict the effect of operating condition on the cell performance in a mathematical model.

  7. Ab Initio Calculations of Transport Properties of Vanadium Oxides

    Science.gov (United States)

    Lamsal, Chiranjivi; Ravindra, N. M.

    2018-04-01

    The temperature-dependent transport properties of vanadium oxides have been studied near the Fermi energy using the Kohn-Sham band structure approach combined with Boltzmann transport equations. V2O5 exhibits significant thermoelectric properties, which can be attributed to its layered structure and stability. Highly anisotropic electrical conduction in V2O5 is clearly manifested in the calculations. Due to specific details of the band structure and anisotropic electron-phonon interactions, maxima and crossovers are also seen in the temperature-dependent Seebeck coefficient of V2O5. During the phase transition of VO2, the Seebeck coefficient changes by 18.9 µV/K, which is close to (within 10% of) the observed discontinuity of 17.3 µV/K.

  8. Fabrication of vanadium nitride by carbothermal nitridation reaction

    International Nuclear Information System (INIS)

    Wang Xitang; Wang Zhuofu; Zhang Baoguo; Deng Chengji

    2005-01-01

    Vanadium nitride is produced from V 2 O 5 by carbon-thermal reduction and nitridation. When the sintered temperature is above 1273 K, VN can be formed, and the nitrogen content of the products increased with the firing temperature raised, and then is the largest when the sintered temperature is 1573 K. The C/V 2 O 5 mass ratio of the green samples is the other key factor affecting on the nitrogen contents of the products. The nitrogen content of the products reaches the most when the C/V 2 O 5 mass ratio is 0.33, which is the theoretical ratio of the carbothermal nitridation of V 2 O 5 . (orig.)

  9. HF/H2O2 treated graphite felt as the positive electrode for vanadium redox flow battery

    Science.gov (United States)

    He, Zhangxing; Jiang, Yingqiao; Meng, Wei; Jiang, Fengyun; Zhou, Huizhu; Li, Yuehua; Zhu, Jing; Wang, Ling; Dai, Lei

    2017-11-01

    In order to improve the electrochemical performance of the positive graphite felt electrode in vanadium flow redox battery, a novel method is developed to effectively modify the graphite felt by combination of etching of HF and oxidation of H2O2. After the etching of HF for the graphite felt at ambient temperature, abundant oxygen-containing functional groups were further introduced on the surface of graphite felt by hydrothermal treatment using H2O2 as oxidant. Benefiting from the surface etching and introduction of functional groups, mass transfer and electrode process can be improved significantly on the surface of graphite felt. VO2+/VO2+ redox reaction on the graphite felt modified by HF and H2O2 jointly (denote: GF-HF/H2O2) exhibits superior electrochemical kinetics in comparison with the graphite felt modified by single HF or H2O2 treatment. The cell using GF-HF/H2O2 as the positive electrode was assembled and its electrochemical properties were evaluated. The increase of energy efficiency of 4.1% for GF-HF/H2O2 at a current density of 50 mA cm-2 was obtained compared with the pristine graphite felt. The cell using GF-HF/H2O2 also demonstrated higher discharge capacity. Our study revealed that HF/H2O2 treatment is an efficient method to enhance the electrochemical performance of graphite felt, further improving the comprehensive energy storage performance of the vanadium flow redox battery.

  10. The extraction of vanadium pentoxide from waste of titanium tetrachloride by various methods

    Directory of Open Access Journals (Sweden)

    Инна Михайловна Гунько

    2015-04-01

    Full Text Available In article the recovery possibility of vanadium pentoxide from wastes, formed as a result of purification from impurities of technical titanium tetrachloride is researched. The purification from impurities is realized by different methods – pulp of lower titanium chlorides, hydrocarbonic reducer and cascade-rectifying purification. Usage of these purification methods leads to formation of anthropogenic wastes. The researches is shown that processing of these wastes is reasonable for the purpose of vanadium pentoxide extraction

  11. Improving the submicro determination of vanadium in natural water using primary-secondary wavelength spectrophotometry

    International Nuclear Information System (INIS)

    Khongven Gao

    1999-01-01

    In acidic solution and in the presence of ammonium persulfate, the conventional reaction of vanadium(5) with gallic acid to form an orange complex has been used for the improvement of the determination of trace amounts of vanadium in water by the updated method named primary-secondary wavelength spectrophotometry. The results show that the analytical precision and accuracy were improved and gave higher determination sensitivity than ordinary spectrophotometry. The relative standard deviations were less than 5.6 % [ru

  12. Temperature Dependence of Uranium and Vanadium Adsorption on Amidoxime-Based Adsorbents in Natural Seawater

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, Li-Jung [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; Gill, Gary A. [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; Tsouris, Costas [Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Rao, Linfeng [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720 USA; Pan, Horng-Bin [Department of Chemistry, University of Idaho, Moscow ID 83844 USA; Wai, Chien M. [Department of Chemistry, University of Idaho, Moscow ID 83844 USA; Janke, Christopher J. [Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Strivens, Jonathan E. [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; Wood, Jordana R. [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; Schlafer, Nicholas [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; D' Alessandro, Evan K. [Rosensteil School of Marine and Atmospheric Chemistry, University of Miami, Miami FL 33149 USA

    2018-01-16

    The apparent enthalpy and entropy of the complexation of uranium (VI) and vanadium (V) with amidoxime ligands grafted onto polyethylene fiber was determined using time series measurements of adsorption capacities in natural seawater at three different temperatures. The complexation of uranium was highly endothermic, while the complexation of vanadium showed minimal temperature sensitivity. Amidoxime-based polymeric adsorbents exhibit significantly increased uranium adsorption capacities and selectivity in warmer waters.

  13. Hydrogen in niobium, tantalum, and vanadium: Structures, phase diagrams, and morphologies

    International Nuclear Information System (INIS)

    Schober, T.

    1978-07-01

    The paper discusses basic aspects of the reactions between the metals niobium, tantalum, vanadium, and hydrogen or deuterium. After an introduction to problems of preparation experimental technqiues for the investigation of hydrides are presented. The possible hydride structures are discussed. With vanadium, there are great differences between the structures of hydrides and deuterides. Detailed mention is also made of recent measurements of the NGH, TaH, VH, and VD phase diagrams. (orig./WBU) [de

  14. The preparation of titanium-vanadium carbide/nickel cermets. Technical report

    International Nuclear Information System (INIS)

    Precht, W.; Sprissler, B.

    1976-01-01

    Titanium/vanadium alloy carbide rods were prepared by a zone melting procedure. Wetting studies were carried out using sections of the fused rods and candidate matrix material. It was established that nickel exhibits excellent wetting of (Ti, V) C, and accordingly cermet blends were prepared and liquid phase sintered. Processing parameters are discussed as well as their effect on the final microstructure. Alternate methods for cermet preparation are offered which use as received titanium carbide and vanadium carbide powders

  15. Utilization of vanadium alloys in the DIII-D Radiative Divertor Program

    International Nuclear Information System (INIS)

    Smith, J.P.; Johnson, W.R.; Stambaugh, R.D.; Trester, P.W.; Smith, D.; Bloom, E.

    1995-10-01

    Vanadium alloys are attractive candidate structural materials for fusion power plants because of their potential for minimum environmental impact due to low neutron activation and rapid activation decay. They also possess favorable material properties for operation in a fusion environment. General Atomics (GA), in conjunction with Argonne National Laboratory (ANL) and Oak Ridge National Laboratory (ORNL), has developed a plan for the utilization of vanadium alloys as part of the Radiative Divertor (RD) upgrade for the DIII-D tokamak. The plan will be carried out in conjunction with General Atomics and the Materials Program of the US Department of Energy (DOE). This application of a vanadium alloy will provide a meaningful step in the development of advanced materials for fusion power devices by: (1) developing necessary materials processing technology for the fabrication of large vanadium alloy components, and (2) demonstrating the in-service behavior of a vanadium alloy (V-4Cr-4Ti) in a tokamak environment. The program consists of three phases: first, small vanadium alloy coupon samples will be exposed in DIII-D at positions in the vessel floor and within the pumping plenum region of the existing divertor structure; second, a small vanadium alloy component will be installed in the existing divertor, and third, during the forthcoming Radiative Divertor modification, scheduled for completion in mid-1997, the upper section of the new double-null, slotted divertor will be fabricated from vanadium alloy product forms. This program also includes research and development (R and D) efforts to support fabrication development and to resolve key issues related to environmental effects

  16. Benchmark experiment on vanadium assembly with D-T neutrons. Leakage neutron spectrum measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kokooo; Murata, I.; Nakano, D.; Takahashi, A. [Osaka Univ., Suita (Japan); Maekawa, F.; Ikeda, Y.

    1998-03-01

    The fusion neutronics benchmark experiments have been done for vanadium and vanadium alloy by using the slab assembly and time-of-flight (TOF) method. The leakage neutron spectra were measured from 50 keV to 15 MeV and comparison were done with MCNP-4A calculations which was made by using evaluated nuclear data of JENDL-3.2, JENDL-Fusion File and FENDL/E-1.0. (author)

  17. Utilization of vanadium alloys in the DIII-D radiative divertor program

    International Nuclear Information System (INIS)

    Smith, J.P.; Johnson, W.R.; Stambaugh, R.D.; Trester, P.W.; Smith, D.; Bloom, E.

    1996-01-01

    Vanadium alloys are attractive candidate structural materials for fusion power plants because of their potential for minimum environmental impact due to low neutron activation and rapid activation decay. They also possess favorable material properties for operation in a fusion environment. General Atomics in conjunction with Argonne National Laboratory and Oak Ridge National Laboratory has developed a plan for the utilization of vanadium alloys as part of the radiative divertor upgrade for the DIII-D tokamak. The plan will be carried out in conjunction with General Atomics and the Materials Program of the US Department of Energy. This application of a vanadium alloy will provide a meaningful step in the development of advanced materials for fusion power devices by: (1) developing necessary materials processing technology for the fabrication of large vanadium alloy components and (2) demonstrating the in-service behavior of a vanadium alloy (V-4Cr-4Ti) in a tokamak environment. The program consists of three phases: first, small vanadium alloy coupon samples will be exposed in DIII-D at positions in the vessel floor and within the pumping plenum region of the existing divertor structure; second, a small vanadium alloy component will be installed in the existing divertor, and third, during the forthcoming radiative divertor modification, scheduled for completion in mid-1997, the upper section of the new double-null, slotted divertor will be fabricated from vanadium alloy product forms. This program also includes research and development efforts to support fabrication development and to resolve key issues related to environmental effects. (orig.)

  18. Determination of trace vanadium using its catalytic effect on the oxidation of gallic acid by bromate

    International Nuclear Information System (INIS)

    Yamane, Takeshi; Fukasawa, Tsutomu

    1976-01-01

    The oxidation of gallic acid by bromate with trace vanadium as catalyst was followed spectrophotometrically by measurements of absorbance change at 420 nm. The reaction rate was obtained graphically from the absorbance vs. time curve in the range of about 15 to 40 min. reaction time. The reaction rate was proportional to the concentration of vanadium(V) in the range 0--120 ng (under the conditions of 5.3x10 -3 M gallic acid, 6.0x10 -3 M potassium bromate, pH 3.8) and 0--30 ng (1.1x10 -2 M gallic acid, 2.7x10 -2 M potassium bromate, pH 3.8). Using this relationship, the concentration of vanadium as low as 0.1 ng/ml can be determined. The relative standard deviations at 50 ng and 20 ng of vanadium were 3.5% (n=14) and 4.0% (n=10), respectively. Iron(III) interfered seriously even when present in 20 times the amounts of vanadium. Up to 60 times, W(VI), Mo(VI) and iodide did not interfere. Many of the other ions examined were found to have no effect or slight effect even when present in 1000 times the amounts of vanadium. Other factors affecting the reaction rate were also studied. (auth.)

  19. Influence of intoxication with vanadium compounds on the intestinal absorption of calcium in the rat

    International Nuclear Information System (INIS)

    Witkowska, D.; Oledzka, R.; Pietrzyk, B.

    1986-01-01

    Calcium is transferred to the plasma after absorption from the gastrointestinal tract and by resorption from the bone. It is recognized that many environmental poisons, e.g. heavy metal, pesticides etc. cause alterations in calcium homeosthasis in human beings and experimental animals. Although vanadium is not considered to be as important a health hazard to man as lead or cadmium it must be nevertheless regarded as a dangerous pollutant. There exists an obvious risk of pollution by and poisoning due to the high vanadium content of crude oil and the industrial use of vanadium as a steel additive. The toxic effects of this element and its compounds in many biological systems have been reviewed in detail but little is known about vanadium influence on calcium metabolism. The present study was undertaken to determine the effect of various treatments with vanadium compounds, containing vanadium as VO 2+ (VOSO 4 ) and VO 3 (NaVO 3 ) ions, exert on calcium transport through the rat duodenum

  20. Low-temperature direct synthesis of mesoporous vanadium nitrides for electrochemical capacitors

    Science.gov (United States)

    Lee, Hae-Min; Jeong, Gyoung Hwa; Kim, Sang-Wook; Kim, Chang-Koo

    2017-04-01

    Mesoporous vanadium nitrides are directly synthesized by a one-step chemical precipitation method at a low temperature (70 °C). Structural and morphological analyses reveal that vanadium nitride consist of long and slender nanowhiskers, and mesopores with diameters of 2-5 nm. Compositional analysis confirms the presence of vanadium in the VN structure, along with oxidized vanadium. The cyclic voltammetry and charge-discharge tests indicate that the obtained material stores charges via a combination of electric double-layer capacitance and pseudocapacitance mechanisms. The vanadium nitride electrode exhibits a specific capacitance of 598 F/g at a current density of 4 A/g. After 5000 charge-discharge cycles, the electrode has an equivalent series resistance of 1.42 Ω and retains 83% of its initial specific capacitance. This direct low-temperature synthesis of mesoporous vanadium nitrides is a simple and promising method to achieve high specific capacitance and low equivalent series resistance for electrochemical capacitor applications.

  1. Structural, physical and electrochemical characteristics of a vanadium oxysulfide, a cathode material for lithium batteries

    Science.gov (United States)

    Ouvrard, G.; Tchangbédji, G.; Deniard, P.; Prouzet, E.

    A vanadium oxysulfide is obtained by a reaction between water solutions of a vanadyl salt and sodium sulfide at room temperature. After drying under mild conditions, the formulation of this phase is V 2O 3S·3H 2O. Thermogravimetric analyses show that it is not possible to remove completely water without losing sulfur. This is in agreement with proton nuclear magnetic resonance experiments which prove that water molecules are tightly bonded to vanadium. Magnetic susceptibility and X-ray absorption spectroscopy measurements allow to define the oxidation states of vanadium and sulfur, (IV) and (-II) respectively. From extended X-ray absorption fine structure spectroscopy at the vanadium K edge and infrared spectroscopy, the local structure around vanadium can be defined as a distorted octahedron, with a vanadyl bond and an opposite sulfur atom. Magnetic susceptibility and X-ray absorption spectroscopy measurements on chemically lithiated compounds show a complex charge transfer from lithium to the host structure upon lithium intercalation. If it appears that vanadium atoms are reduced, a possible role of sulfur atoms in the redox process has to be considered. Cycling tests of lithium batteries whose positive consists of oxysulfide are promising with 70 cycles under a regime of {C}/{8}, without noticeable loss in capacity of 120 Ah/kg.

  2. The Influence of Vanadium Microalloying on the Production of Thin Slab Casting and Direct Rolled Steel Strip

    Science.gov (United States)

    Li, Yu; Milbourn, David

    Vanadium microalloying is highly effective in high strength strip steels produced by thin slab casting and direct rolled process. Because of the high solubility of V(C,N) in austenite, vanadium is likely to remain in solution during casting, equalisation and rolling. Vanadium microalloyed steels have better hot ductility and are less prone to transverse cracking than niobium containing steels. Despite a coarse as-cast austenite grain size before rolling, significant grain refinement can be achieved in vanadium microalloyed steels by repeated recrystallization during rolling, resulting in a fine uniform ferrite microstructure in final strip. Almost all vanadium present in microalloyed steels is available to precipitate in ferrite as very fine particles, contributing to precipitation strengthening. Vanadium microalloyed steels show less sensitivity to rolling process variables and exhibit excellent combination of strength and toughness.

  3. Critical V2O5/TeO2 Ratio Inducing Abrupt Property Changes in Vanadium Tellurite Glasses.

    Science.gov (United States)

    Kjeldsen, Jonas; Rodrigues, Ana C M; Mossin, Susanne; Yue, Yuanzheng

    2014-12-26

    Transition metal containing glasses have unique electrical properties and are therefore often used for electrochemical applications, such as in batteries. Among oxide glasses, vanadium tellurite glasses exhibit the highest electronic conductivity and thus the high potential for applications. In this work, we investigate how the dynamic and physical properties vary with composition in the vanadium tellurite system. The results show that there exists a critical V(2)O(5) concentration of 45 mol %, above which the local structure is subjected to a drastic change with increasing V(2)O(5), leading to abrupt changes in both hardness and liquid fragility. Electronic conductivity does not follow the expected correlation to the valence state of the vanadium as predicted by the Mott-Austin equation but shows a linear correlation to the mean distance between vanadium ions. These findings could contribute to designing optimum vanadium tellurite compositions for electrochemical devices. The work gives insight into the mechanism of electron conduction in the vanadium tellurite systems.

  4. The Vanadium Window with special reference to Joseph and James Flannery's contribution to the American steel and radium industries

    International Nuclear Information System (INIS)

    Lubenau, J. O.; Mould, R. F.

    2008-01-01

    The discovery of vanadium is described and the founding of the American Vanadium Company by Joseph Flannery (1867-1920) and its headquarters building in Pittsburgh in which was the stained glass window depicting the origin of the name Vanadium. Company orders for vanadium steel were obtained for the Panama canal and from Henry Ford. When his sister was diagnosed with cancer, Joseph Flannery withdrew from his vanadium interests and founded the Standard Chemical and Radium Chemical Companies which were the major suppliers of radium in the USA in the 1920s (before the Union Minicre du Haut Katanga commenced its commercial operations), processed from American mined carnotite in Colorado and Utah. Significant contributions to these enterprises involving vanadium and radium were also made by Joseph's elder brother, James Flannery (1848-1920). (author)

  5. Statistical analysis on hollow and core-shell structured vanadium oxide microspheres as cathode materials for Lithium ion batteries

    Directory of Open Access Journals (Sweden)

    Xing Liang

    2018-06-01

    Full Text Available In this data, the statistical analyses of vanadium oxide microspheres cathode materials are presented for the research article entitled “Statistical analyses on hollow and core-shell structured vanadium oxides microspheres as cathode materials for Lithium ion batteries” (Liang et al., 2017 [1]. This article shows the statistical analyses on N2 adsorption-desorption isotherm and morphology vanadium oxide microspheres as cathode materials for LIBs. Keywords: Adsorption-desorption isotherm, Pore size distribution, SEM images, TEM images

  6. Development of cloud point extraction - UV-visible spectrophotometric method for vanadium (V) determination in hydrogeochemical samples

    International Nuclear Information System (INIS)

    Durani, Smeer; Mathur, Neerja; Chowdary, G.S.

    2007-01-01

    The cloud point extraction behavior (CPE) of vanadium (V) using 5,7 dibromo 8-hydroxyquinoline (DBHQ) and triton X 100 was investigated. Vanadium (V) was extracted with 4 ml of 0.5 mg/ml DBHQ and 6 ml of 8% (V/V) triton X 100 at the pH 3.7. A few hydrogeochemical samples were analysed for vanadium using the above method. (author)

  7. Self-assembling Synthesis of Vanadium Oxide Nanotubes and Simple Determination of the Content of Ⅴ(Ⅳ)

    Institute of Scientific and Technical Information of China (English)

    MAI Li-qiang; CHEN Wen; XU Qing; ZHU Quan-yao; HAN Chun-hua; PENG Jun-feng

    2003-01-01

    High-yielding low-cost vanadium oxide nanotubes were prepared by the hydrothermal self-assembling process from vanadium pentoxide and organic molecules as structure-directing templates. Moreover, a new method was discovered for determining the content of V (Ⅳ) in vanadium oxide nanotubes by thermogravimetric analysis ( TGA ). This method is simple, precise and feasible and can be extended to determine the content of low oxidation state in the other transition metal oxide nanomaterials.

  8. Determination of micro amounts of vanadium by oxidative coupling of α-naphthol and p-phenylenediamine

    International Nuclear Information System (INIS)

    Hainberger, S.J.; Damasceno, R.N.

    1975-01-01

    A sensitive determination of vanadium is described. In the presence of the necessary amount of potassium chlorate and small amounts of vanadium, α-naphthol and p-phenylenediamine react to yield a dyestuff, which exhibits an absorption maximum at 345 nm. The Lambert-Beer law is followed at 0.008-0.12 μg vanadium per ml. The molar extinction amounts to 54 x 10 4 .mol -1 The removal of the interfering cations is described. (author)

  9. Concise N-doped Carbon Nanosheets/Vanadium Nitride Nanoparticles Materials via Intercalative Polymerization for Supercapacitors.

    Science.gov (United States)

    Tan, Yongtao; Liu, Ying; Tang, Zhenghua; Wang, Zhe; Kong, Lingbin; Kang, Long; Liu, Zhen; Ran, Fen

    2018-02-13

    N-doped carbon nanosheets/vanadium nitride nanoparticles (N-CNS/VNNPs) are synthesized via a novel method combining surface-initiated in-situ intercalative polymerization and thermal-treatment process in NH 3 /N 2 atmosphere. The pH value of the synthesis system plays a critical role in constructing the structure and enhancing electrochemical performance for N-CNS/VNNPs, which are characterized by SEM, TEM, XRD, and XPS, and measured by electrochemical station, respectively. The results show that N-CNS/VNNPs materials consist of 2D N-doped carbon nanosheets and 0D VN nanoparticles. With the pH value decreasing from 2 to 0, the sizes of both carbon nanosheets and VN nanoparticles decreased to smaller in nanoscale. The maximum specific capacitance of 280 F g -1 at the current density of 1 A g -1 for N-CNS/VNNPs is achieved in three-electrode configuration. The asymmetric energy device of Ni(OH) 2 ||N-CNS/VNNPs offers a specific capacitance of 89.6 F g -1 and retention of 60% at 2.7 A g -1 after 5000 cycles. The maximum energy density of Ni(OH) 2 ||N-CNS/VNNPs asymmetric energy device is as high as 29.5 Wh kg -1 .

  10. [Spectralsignatures of nickel and vanadium supported photocatalysts and their photocatalytic properties].

    Science.gov (United States)

    Hai, Feng; Zhang, Qian-Cheng; Wang, Zhi-Wei; Jian, Li

    2011-04-01

    Using SiO2, activated carbon (AC) and Al2O3 as supports, the supported photocatalysts Ni-V-O/SiO2, Ni-V-O/AC and Ni-V-O/Al2O3 were prepared by impregnation method, and their spectralsignatures were investigated. The carbonylation of methanol with CO2 under UV irradiation was used as a probe reaction to compare the photocatalytic performance of the prepared catalysts. Integrated with the testing results of carbonylation, the effects of different supports on selectivity for the carbonylation products of methyl formate (MF) and dimethyl carbonate (DMC) were discussed by pyridine-IR and UV-Vis techniques. XRD results showed that the particles of nickel and vanadium supported on SiO2 had the highest degree of dispersion. Results of pyridine-IR indicated that all catalysts retained Lewis acid sites. The acid strength was different from catalyst samples with different supports but with the same active components. The acid strengths could be arranged as follows: Ni-V-O/SiO2 > Ni-V-O/Al2 O3 > Ni-V-O/AC. Different acid strengths exhibited different influence on the selectivity of products MF and DMC of carbonylation. The surface acid strengths of catalysts were the major factor influencing the selectivity of carbonylation products.

  11. Nickel, vanadium, and lead as indicators of sediment contamination of marina, refinery, and shipyard areas.

    Science.gov (United States)

    Pereira, Thayane Lúcia; Wallner-Kersanach, Mônica; Costa, Luiza Dy Fonseca; Costa, Daniel Pereira; Baisch, Paulo Roberto Martins

    2018-01-01

    Metallic elements found in the aquatic environment may originate in areas where petroleum is refined and vessels are maintained and repaired. This study aims to assess contamination caused by nickel (Ni), lead (Pb), and vanadium (V) in sediment of the Lagoa dos Patos estuary (RS, Brazil) and to evaluate them as indicators of areas under the influence of petroleum products and antifouling paints. Surface sediments were collected in summer and in winter in areas of marinas, shipyards, refinery, and a control station. High Pb and V concentrations in shipyards and at the Yacht Club showed that some organisms may be affected by toxicity. High Pb results of the index of geoaccumulation (Igeo) were found at the Yacht Club and shipyards. Al, Ni, and V had similar distribution in the sediment in both seasons. Ni and V had high relation in winter at the Yacht Club and at the Santos Shipyard, thus suggesting that these elements come mainly from petroleum products. The same happened to the relations between Pb and V, as well as Pb and Ni at the Santos Shipyard. These elements are employed as useful tools as indicators to identify places with moderate to high localized anthropogenic inputs of petroleum derivatives and antifouling paints.

  12. A high-performance carbon nanoparticle-decorated graphite felt electrode for vanadium redox flow batteries

    International Nuclear Information System (INIS)

    Wei, L.; Zhao, T.S.; Zhao, G.; An, L.; Zeng, L.

    2016-01-01

    Highlights: • Propose a carbon nanoparticle-decorated graphite felt electrode for VRFBs. • The energy efficiency is up to 84.8% at 100 mA cm"−"2. • The new electrode allows the peak power density to reach 508 mW cm"−"2. - Abstract: Increasing the performance of vanadium redox flow batteries (VRFBs), especially the energy efficiency and power density, is critically important to reduce the system cost to a level for widespread commercialization. Unlike conventional VRFBs with flow-through structure, in this work we create a VRFB featuring a flow-field structure with a carbon nanoparticle-decorated graphite felt electrode for the battery. This novel structure, exhibiting a significantly reduced ohmic loss through reducing electrode thickness, an increased surface area and improved electrocatalytic activity by coating carbon nanoparticles, allows the energy efficiency up to 84.8% at a current density of as high as 100 mA cm"−"2 and the peak power density to reach a value of 508 mW cm"−"2. In addition, it is demonstrated that the battery with this proposed structure exhibits a substantially improved rate capability and capacity retention as opposed to conventional flow-through structured battery with thick graphite felt electrodes.

  13. Enhanced vanadium redox flow battery performance using graphene nanoplatelets to decorate carbon electrodes

    Science.gov (United States)

    Sankar, Abhinandh; Michos, Ioannis; Dutta, Indrajit; Dong, Junhang; Angelopoulos, Anastasios P.

    2018-05-01

    Rotating Disk Electrode (RDE) measurements on model glassy carbon (GC) substrates and Cyclic Voltammetry on more practical commercial carbon supports are used to demonstrate that the kinetics of the positive VO2+/VO2+ redox reaction can be substantially enhanced by using electrostatic layer-by-layer assembly (LbL) to decorate their surface with graphene nanoplatelets (GNPs). An exchange current density, i0, is obtained that is more than two orders of magnitude greater than that observed with standard carbon supported Pt nanocatalyst with the deposition of only 20 GNP layers. Tafel slope analysis is compared to electron microscopy imaging to conclude that while faster redox kinetics is associated with an increase in the available active area, the prevalence of smaller GNPs and associated edge sites the can attenuate activity gains with increasing number of layers. Practical implementation to existing Vanadium Redox Flow Battery (VRFB) configurations was demonstrated through the application of a 370 nm (20 layer) LbL GNP coating on carbon felt (CF). The GNP coating yielded a 5% increase relative in voltage and overall efficiency of charge discharge curves obtained under typical VRFB cell operating conditions at 40 mA cm-2. Furthermore, a substantial increase in the discharge time is observed with this GNP coating on CF.

  14. Performance enhancement in vanadium redox flow battery using platinum-based electrocatalyst synthesized by polyol process

    International Nuclear Information System (INIS)

    Jeong, Sanghyun; Kim, Sunhoe; Kwon, Yongchai

    2013-01-01

    Sluggish reaction rate of [VO] 2+ /[VO 2 ] + redox couple is an obstacle to be addressed in vanadium redox flow battery (VRFB). To improve the slow reaction rate, Pt/C catalyst synthesized by polyol method is suggested. Its catalytic activity, reaction reversibility and charge–discharge performance are evaluated by half cell and single cell tests, while its crystal structure, particle size and particle distribution are measured by XRD and TEM. The XRD and TEM measurements show the polyol Pt/C catalyst has larger electrochemically active surface (EAS) area and smaller particle size than commercial Pt/C catalyst. When catalytic activities of all the catalysts are estimated, the Pt-included catalysts demonstrate high peak current ratio, small peak potential difference and high electron transfer rate constant, confirming that their catalytic activity and reaction reversibility are excellent. In charge–discharge performance tests, the catalysts indicate high efficiencies as well as low overpotential and internal resistance. Excellent performances of the Pt-included catalysts are attributed to positively charged Pts that serve as active sites for activating [VO] 2+ /[VO 2 ] + reaction. Indeed, adoption of the Pt-included catalysts, especially, use of the polyol Pt/C consisting of uniform and small particles helps improve performance of VRFB

  15. Kinetic enhancement via passive deposition of carbon-based nanomaterials in vanadium redox flow batteries

    Science.gov (United States)

    Aaron, Doug; Yeom, Sinchul; Kihm, Kenneth D.; Ashraf Gandomi, Yasser; Ertugrul, Tugrul; Mench, Matthew M.

    2017-10-01

    Addition of carbon-based nanomaterials to operating flow batteries accomplishes vanadium redox flow battery performance improvement. Initial efforts focus on addition of both pristine graphene and vacuum-filtered reduced graphene oxide (rGO) film on carbon paper supporting electrodes. While the former is unable to withstand convective flow through the porous electrode, the latter shows measurable kinetic improvement, particularly when laid on the polymer electrolyte membrane (PEM) side of the electrode; in contrast to the kinetic performance gain, a deleterious impact on mass transport is observed. Based on this tradeoff, further improvement is realized using perforated rGO films placed on the PEM side of the electrodes. Poor mass transport in the dense rGO film prompts identification of a more uniform, passive deposition method. A suspension of rGO flakes or Vulcan carbon black (XC-72R), both boasting two orders-of-magnitude greater specific surface area than that of common carbon electrodes, is added to the electrolyte reservoirs and allowed to passively deposit on the carbon paper or carbon felt supporting electrodes. For common carbon felt electrodes, addition of rGO flakes or XC-72R enables a tripling of current density at the same 80% voltage efficiency.

  16. Mesoporous coaxial titanium nitride-vanadium nitride fibers of core-shell structures for high-performance supercapacitors.

    Science.gov (United States)

    Zhou, Xinhong; Shang, Chaoqun; Gu, Lin; Dong, Shanmu; Chen, Xiao; Han, Pengxian; Li, Lanfeng; Yao, Jianhua; Liu, Zhihong; Xu, Hongxia; Zhu, Yuwei; Cui, Guanglei

    2011-08-01

    In this study, titanium nitride-vanadium nitride fibers of core-shell structures were prepared by the coaxial electrospinning, and subsequently annealed in the ammonia for supercapacitor applications. These core-shell (TiN-VN) fibers incorporated mesoporous structure into high electronic conducting transition nitride hybrids, which combined higher specific capacitance of VN and better rate capability of TiN. These hybrids exhibited higher specific capacitance (2 mV s(-1), 247.5 F g(-1)) and better rate capability (50 mV s(-1), 160.8 F g(-1)), which promise a good candidate for high-performance supercapacitors. It was also revealed by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) characterization that the minor capacitance fade originated from the surface oxidation of VN and TiN.

  17. Bismuth nanoparticle decorating graphite felt as a high-performance electrode for an all-vanadium redox flow battery.

    Science.gov (United States)

    Li, Bin; Gu, Meng; Nie, Zimin; Shao, Yuyan; Luo, Qingtao; Wei, Xiaoliang; Li, Xiaolin; Xiao, Jie; Wang, Chongmin; Sprenkle, Vincent; Wang, Wei

    2013-03-13

    Employing electrolytes containing Bi(3+), bismuth nanoparticles are synchronously electrodeposited onto the surface of a graphite felt electrode during operation of an all-vanadium redox flow battery (VRFB). The influence of the Bi nanoparticles on the electrochemical performance of the VRFB is thoroughly investigated. It is confirmed that Bi is only present at the negative electrode and facilitates the redox reaction between V(II) and V(III). However, the Bi nanoparticles significantly improve the electrochemical performance of VRFB cells by enhancing the kinetics of the sluggish V(II)/V(III) redox reaction, especially under high power operation. The energy efficiency is increased by 11% at high current density (150 mA·cm(-2)) owing to faster charge transfer as compared with one without Bi. The results suggest that using Bi nanoparticles in place of noble metals offers great promise as high-performance electrodes for VRFB application.

  18. Corrosion behavior of a positive graphite electrode in vanadium redox flow battery

    International Nuclear Information System (INIS)

    Liu Huijun; Xu Qian; Yan Chuanwei; Qiao Yonglian

    2011-01-01

    Graphical abstract: The overpotential for gas evolution on positive graphite electrode decreases due to the functional groups of COOH and C=O introduced on the surface of graphite electrode during corrosion process, which can self-catalyze the oxidation of carbon atoms therefore, accelerates corrosion process. Highlights: → Initial potential for gas evolution is higher than 1.60 V vs SCE. → Factors affecting the graphite corrosion are investigated. → Functional groups of COOH and C=O introduced during corrosion process. → The groups can self-catalyze the oxidation of carbon atoms. - Abstract: The graphite plate is easily suffered from corosion because of CO 2 evolution when it acts as the positive electrode for vanadium redox flow battery. The aim is to obtain the initial potential for gas evolution on a positive graphite electrode in 2 mol dm -3 H 2 SO 4 + 2 mol dm -3 VOSO 4 solution. The effects of polarization potential, operating temperature and polarization time on extent of graphite corrosion are investigated by potentiodynamic and potentiostatic techniques. The surface characteristics of graphite electrode before and after corrosion are examined by scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. The results show that the gas begins to evolve on the graphite electrode when the anodic polarization potential is higher than 1.60 V vs saturated calomel electrode at 20 deg. C. The CO 2 evolution on the graphite electrode can lead to intergranular corrosion of the graphite when the polarization potential reaches 1.75 V. In addition, the functional groups of COOH and C=O introduced on the surface of graphite electrode during corrosion can catalyze the formation of CO 2 , therefore, accelerates the corrosion rate of graphite electrode.

  19. Diel cycles in dissolved barium, lead, iron, vanadium, and nitrite in a stream draining a former zinc smelter site near Hegeler, Illinois

    Science.gov (United States)

    Kay, R.T.; Groschen, G.E.; Cygan, G.; Dupre, David H.

    2011-01-01

    Diel variations in the concentrations of a number of constituents have the potential to substantially affect the appropriate sampling regimen in acidic streams. Samples taken once during the course of the day cannot adequately reflect diel variations in water quality and may result in an inaccurate understanding of biogeochemical processes, ecological conditions, and of the threat posed by the water to human health and the associated wildlife. Surface water and groundwater affected by acid drainage were sampled every 60 to 90. min over a 48-hour period at a former zinc smelter known as the Hegeler Zinc Superfund Site, near Hegeler, Illinois. Diel variations related to water quality in the aquifer were not observed in groundwater. Diel variations were observed in the temperature, pH, and concentration of dissolved oxygen, nitrite, barium, iron, lead, vanadium, and possibly uranium in surface water. Temperature, dissolved oxygen, nitrite, barium, lead, and uranium generally attained maximum values during the afternoon and minimum values during the night. Iron, vanadium, and pH generally attained minimum values during the afternoon and maximum values during the night. Concentrations of dissolved oxygen were affected by the intensity of photosynthetic activity and respiration, which are dependent upon insolation. Nitrite, an intermediary in many nitrogen reactions, may have been formed by the oxidation of ammonium by dissolved oxygen and converted to other nitrogen species as part of the decomposition of organic matter. The timing of the pH cycles was distinctly different from the cycles found in Midwestern alkaline streams and likely was the result of the photoreduction of Fe3+ to Fe 2+ and variations in the intensity of precipitation of hydrous ferric oxide minerals. Diel cycles of iron and vanadium also were primarily the result of variations in the intensity of precipitation of hydrous ferric oxide minerals. The diel variation in the concentrations of lead, uranium

  20. Leaching of vanadium from sulphuric acid manufacture spent catalysts

    Directory of Open Access Journals (Sweden)

    García, Diego Juan

    2001-02-01

    Full Text Available Recovery of vanadium contained in spent catalysts from the manufacture of sulphuric acid has been studied in this work, resulting in an industrial multistage process for the treatment of them avoiding direct deposition or dumping. Characterization of supplied spent catalysts samples, confirmed vanadium levels showed in the literature. The study of variables influencing leaching process: type of leaching agent, leaching agent concentration, S/L ratio, stirring speed and temperature, allows to fix the most advantageous conditions using industrial application criterion and verifying that the process is difusión controlled. The work is completed by developing an industrial leaching cycle simulation with the aim of reproducing real performance of spent catalyst, proposing operating conditions, and verifying the non-toxic character of the final residue obtained.

    En el presente trabajo se ha estudiado la recuperación del vanadio contenido en los catalizadores agotados procedentes de la fabricación del ácido sulfúrico, planteando un proceso industrial multietapa para el tratamiento de estos residuos, evitando su deposición o vertido directos. La caracterización de las muestras de catalizadores agotados disponibles confirmó los valores encontrados en la bibliografía. Se estudiaron las variables que influyen en el proceso de lixiviación (tipo de agente de lixiviación y concentración del mismo, relación S/L, velocidad de agitación y temperatura definiendo las condiciones más adecuadas desde el punto de vista industrial y verificando que el proceso está controlado por mecanismos difusionales. El trabajo se completa con la simulación de un ciclo industrial de lavado del catalizador y la verificación de la nula toxicidad de los lixiviados obtenidos por degradación del residuo final. 24 Aplicación de la resistencia de ruido al estudio de pinturas ricas en zinc Noise resistance applied to the study of zinc rich paints

  1. El vanadio, un elemento ambiguo Vanadium, an ambiguous element

    Directory of Open Access Journals (Sweden)

    Graciela Beatriz García

    2006-12-01

    Full Text Available El vanadio (V se encuentra en 68 minerales diferentes, en los combustibles derivados del petróleo y el carbón y se utiliza principalmente en la industria metalúrgica. Para los humanos, la principal fuente de exposición al V es la contaminación atmosférica producida por la quema de combustibles. En los animales se ha demostrado que algunos compuestos del V son hepatotóxicos, nefrotóxicos, neurotóxicos, carcinogénicos y que afectan a la reproducción y al desarrollo de los fetos y lactantes. Sin embargo, los efectos toxicológicos finales, motivo de preocupación para las personas son la genotoxicidad y la irritación de las vías respiratorias. Por otra parte, los compuestos del V han sido objeto de investigación como agentes que disminuyen los niveles séricos de glucosa, como antihipertensivos, como anorexígenos y como anticancerígenos. El V, de efectos biológicos notables, debe ser más estudiado con el fin de conocer los mecanismos de su acción biológica y para poder determinar tanto los riesgos a su exposición como sus posibles usos farmacológicos en beneficio humano.Vanadium (V occurs in about 68 minerals and in fossil fuels and it is mainly used in steel industry. Air pollution produced by oil and coal burning is the main exposure source for human beings. Reproductive and developmental toxicity, hepatotoxicity, nephrotoxicity, neurotoxicity and carcinogenicity have been found in some vanadium compound exposed animals. Nevertheless, the toxicological end-points of concern for humans are genotoxicity and respiratory tract irritation. On the other hand, V compounds have been studied as anti-diabetic, as antihypertensive, as anorexigen and as anti-carcinogenic. V, which has remarkable biological effects should be studied in order to elucidate its biological mechanisms and to determine either its expositional risks or its pharmacological properties for human benefit.

  2. KOH etched graphite felt with improved wettability and activity for vanadium flow batteries

    International Nuclear Information System (INIS)

    Zhang, Zhengyang; Xi, Jingyu; Zhou, Haipeng; Qiu, Xinping

    2016-01-01

    Highlights: • GF electrode is activated by KOH etching method for VFB application. • The wettability and activity of eGF electrode towards VO 2+ /VO 2 + and V 2+ /V 3+ couples are improved. • VFB with eGF electrode can run stable at current densities range from 50 to 250 mA cm −2 . • Cycling test at current density of 150 mA cm −2 confirms the superior durability of eGF electrode. - Abstract: In this work, a simple and effective method to activate graphite felt (GF) electrode by using KOH as etching agent is studied for vanadium flow battery (VFB) application. The surface of GF is etched by KOH at 800 °C to generate micropores and attain oxygen-containing functional groups, resulting in greatly improved electrolyte accessibility. Surface morphology, oxygen distribution and microstructure of the KOH etched graphite felts (eGFs) are characterized by SEM, EDX, XPS, XRD and Raman techniques. Due to the abundant exposed edge carbon sites and oxygen-containing functional groups introduced by KOH activation, electrochemical activity of eGFs towards both VO 2+ /VO 2 + and V 2+ /V 3+ redox couples are remarkably improved comparing with GF. In particular, eGF-2 (mass ratio of KOH/GF = 1.25) exhibits the best electrochemical activity and VFB performance among all eGFs. Moreover, the VFB with eGF-2 electrode can run at current density up to 250 mA cm −2 with the energy efficiency of 64%. Long-term cycle life test at higher current density of 150 mA cm −2 confirms the outstanding stability of eGF-2 electrode.

  3. Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts

    International Nuclear Information System (INIS)

    Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

    2015-01-01

    Highlights: • V-doped TiO 2 /diatomite composite photocatalyst was synthesized. • The physiochemical property and solar light photoactivity were characterized. • The presence and influence of V ions in TiO 2 matrix was systematically analyzed. • The photocatalysis for Rhodamine B were studied under solar light illumination. - Abstract: V-doped TiO 2 /diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol–gel method. The diatomite was responsible for the well dispersion of TiO 2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO 2 /diatomite hybrids showed red shift in TiO 2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO 2 bandgap due to V 4+ ions substituted to Ti 4+ sites. The 0.5% V-TiO 2 /diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO 2 /diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V 4+ ions incorporated in TiO 2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO 2 to produce superoxide radicals ·O 2 – , while V 5+ species presented on the surface of TiO 2 particles in the form of V 2 O 5 contributed to e – –h + separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability

  4. Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts.

    Science.gov (United States)

    Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

    2015-03-21

    V-doped TiO2/diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol-gel method. The diatomite was responsible for the well dispersion of TiO2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO2/diatomite hybrids showed red shift in TiO2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO2 bandgap due to V(4+) ions substituted to Ti(4+) sites. The 0.5% V-TiO2/diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO2/diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V(4+) ions incorporated in TiO2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO2 to produce superoxide radicals ˙O2(-), while V(5+) species presented on the surface of TiO2 particles in the form of V2O5 contributed to e(-)-h(+) separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Optical and electrochromic properties of sol-gel deposited Ti- doped vanadium oxide films

    International Nuclear Information System (INIS)

    Oezer, N.; Sabuncu, S.

    1997-01-01

    Because of the yellowish color, vanadium oxide films in the as deposited state is not as favorable as transparent coatings for most elector chromic devices. an interesting possibility to alter the yellowish colours is the doping with other non-absorbing metal oxides. Ti doped vanadium oxide films with various amounts of titanium were synthesized and investigated as transparent counter electrodes for electrochromic transmissive device application. Electrochromic titanium doped vanadium pentoxide (V sub 2 O 5) coatings were prepared by the sol-gel dip coating technique. The coating solutions were synthesized from vanadium tri(isopropoxide) precursors. X-ray diffraction (XRD) studies showed that the sol-gel deposited doped films heat treated at temperatures below 350 degree centigrade, were amorphous, whereas hose heat treated at higher temperatures were slight y crystalline. The optical and electrochemical properties of the Ti doped vanadium oxide films has been investigated in 0.1 m LiClO sub 4 propylene carbonate solution color changes by dropping were noted for all investigated films exhibits good electrochemical cycling (CV) measurements also showed that Ti doped V sub 2 O sub 5 films exhibits good electrochemical cycling reversibility, 'in situ' optical measurement revealed that those films exhibits good electrochemical cycling the spectra range 300 < lambda < 800 nm and change color between yellow and light green. The change in visible transmittance was 25 % for 5% Ti doped film. (author)

  6. Electrochemical behaviour of a vanadium anode in phosphoric acid and phosphate solutions

    International Nuclear Information System (INIS)

    Alonzo, V.; Darchen, A.; Fur, E. Le; Pivan, J.Y.

    2006-01-01

    Anodic polarisation of a vanadium electrode has been studied in H 3 PO 4 solutions and some phosphate solutions: LiH 2 PO 4 , NaH 2 PO 4 , KH 2 PO 4 and NH 4 H 2 PO 4 . The anodic behaviour of a vanadium electrode showed similarities in weak concentrated H 3 PO 4 , in LiH 2 PO 4 and NaH 2 PO 4 solutions: the polarisation curve exhibited a current peak followed by current oscillations and then a current plateau. Concentrated H 3 PO 4 , 1 M KH 2 PO 4 and NH 4 H 2 PO 4 solutions involved vanadium passivation with a very slight current density plateau. Yellow compound identified to VOPO 4 .2H 2 O was obtained after controlled potential oxidation of vanadium in 5-10 M H 3 PO 4 . Green products were obtained in 1 M phosphate solutions and in 1-3 M H 3 PO 4 on vanadium anode after controlled potential electrolysis. All these vanadophosphate compounds contained the monovalent cation which was present in the solution

  7. Vanadium century record from Caribbean reef corals: A tracer of oil pollution in Panama

    International Nuclear Information System (INIS)

    Guzman, H.M.; Jarvis, K.E.

    1996-01-01

    The Caribbean region is potentially one of the largest oil-producing areas in the world, and contamination by petroleum is threatening the marine environment. Vanadium (V), an abundant element in crude oils, was used as proxy tracer of oil pollution along the Caribbean coast of Panama. We develop a century chronology based on the concentration of vanadium (using ICP-MS) incorporated into annual growth bands of coral skeletons. The chronology for vanadium showed a relatively clear pattern where background seawater concentrations were observed in the early history of the corals followed by an increase after 1962, the initiation of a refinery operation. The vanadium chronology suggests that a major degradation process in the coastal zone could have started around the 1960s, but we were unable to confirm such an assumption due to the lack of long-term ecological and pollution data. The gradual increase of vanadium into the marine environment might be used as a pointer to oil pollution. 46 refs, 4 figs, 1 tab

  8. Study on wear resistance of vanadium alloying compacted/vermicular graphite cast iron

    International Nuclear Information System (INIS)

    Park, Yoon Woo

    1987-01-01

    Wear resistance of the Compacted/Vermicular graphite cast irons was studied by changing the vanadium content in the cast irons. The results obtained in this work are summarized as follows. 1. When the same amount of vanadium was added to the flake graphite cast iron, spheroidal graphitecast iron and Compacted/Vermicular graphite cast iron, spheroidal graphite cast iron and Compacted/Vermicular graphite cast iron wear resistance decreased in following sequence, that is, flake graphite cast iron> spheroidal graphite cast iron>Compacted/Vermicular graphite cast iron. 2. Addition of vanadium to the Compacted/Vermicular cast iron leaded to a remarkable increase in hardness because it made the amount of pearlite in matrix increase. 3. Addition of vanadium to the compacted/Vermicular graphite cast iron significantly enhanced wear resistance and the maximum resistance was achieved at about 0.36% vanadium. 4. The maximum amount of wear apppeared at sliding speed of about 1.4m/sec and wear mode was considered to be oxidation abrasion from the observation of wear tracks. (Author)

  9. Temperature dependence of the damage microstructures in neutron-irradiated vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Horton, L.L.; Farrell, K.

    1983-01-01

    Vanadium and vanadium with boron carbide additions (V-B/sub 4/C) were irradiated to approx. 1 dpa in the Oak Ridge Research Reactor at controlled temperatures ranging from 455 to 925 K. The V-B/sub 4/C alloy was enriched in /sup 10/B, which produced approx. 3900 at. ppM helium. In the vanadium specimens, the dislocation microstructures varied from clusters of small (< 50 nm diam) dislocation loops (455 to 625 K) to larger, homogeneously distributed loops at higher temperatures. Their Burgers vectors were a/2<111>. The V-B/sub 4/C specimens contained only tangled dislocation segments. Cavities were observed in all specimens. The cavity concentration decrease and the average diameter increased with increasing irradiation temperature. At 725 K, the maximum swelling was observed in both the vanadium (0.1%) and V-B/sub 4/C (1.4%). At comparable temperatures the cavities in the V-B/sub 4/C specimens were smaller and more numerous than those in the vanadium specimens. Helium bubbles were found on the grain boundaries in all of the V-B/sub 4/ specimens.

  10. Effect of organic additives on positive electrolyte for vanadium redox battery

    Energy Technology Data Exchange (ETDEWEB)

    Li Sha [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Huang Kelong, E-mail: lisha_csu@163.com [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Liu Suqin; Fang Dong; Wu Xiongwei; Lu Dan; Wu Tao [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

    2011-06-30

    Highlights: > Four organics as electrolyte additives of vanadium redox battery. > Changes are examined in the electrochemical properties of vanadium redox battery. > D-sorbitol is a suitable additive to the electrolyte for the vanadium redox battery. > The mechanism of improvement is discussed in detail. - Abstract: Fructose, mannitol, glucose, D-sorbitol are explored as additives in electrolyte for vanadium redox battery (VRB), respectively. The effects of additives on electrolyte are studied by cyclic voltammetry (CV), charge-discharge technique, electrochemical impedance spectroscopy (EIS) and Raman spectroscopy. The results indicate that the vanadium redox cell using the electrolyte with the additive of D-sorbitol exhibits the best electrochemical performance (the energy efficiency 81.8%). The EIS results indicate that the electrochemical activity of the electrolyte is improved by adding D-sorbitol, which can be interpreted as the increase of available (-OH) groups providing active sites for electron transfer. The Raman spectra show that VO{sup 2+} ions take part in forming a complex with the D-sorbitol, which not only improve solubility of V(V) electrolyte, but also provide more activity sites for the V(IV)/V(V) redox reaction.

  11. Wet sample digestion for quantification of vanadium(V) in serum by electrothermal atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Heinemann, G.; Vogt, W.; Jacob, K.

    1999-01-01

    Three types of pressure digestion systems used prior to the determination of the ultratrace element vanadium by electrothermal atomic absorption spectrometry were evaluated: The high-pressure ashing (HPA) system, the DAB III pressure digestion system and the pressurized microwave digestion (PMD) system. Complete sample digestion and no loss of graphite tube sensitivity as well as reliable vanadium values could only be achieved with HPA digests of freeze-dried serum. The mean recovery rate was 98% and no loss of tube sensitivity could be observed. Using non-lyophilized serum the mean recovery rate was 70%. The DAB III digestion system, vicarious for closed pressure digestion in steel bombs with an allowable temperature up to about 200C, cannot be recommended to mineralize human biological material for vanadium determinations, because the remaining not completely decomposed organic compounds extracted together with the vanadium-cupferron complex caused a marked carbon-buildup and formation of carbides in the graphite tube were found to change the shape of the absorption signals distinctly, and to decline the tube sensitivity strongly (about 25%) so that reliable results cannot be achieved. The recovery rate was too low in general (about 50%). In addition, a subsequent treatment of the DAB III digests with perchloric acid was unsuccessful. The PMD system proved to be not suited, because the samples became highly contaminated by vanadium possibly from the titan seal. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  12. Determination of factor of hydrogen permeation reduction (PRF) for different protective coatings over vanadium

    International Nuclear Information System (INIS)

    Afanasyev, S.; Kulsartov, T.; Shestakov, V.; Chikhray, Y.; Smith, D.

    2002-01-01

    Selection of structural materials for liquid-metal system as well as for another system and constructions of nuclear energy plants must be carried out and based on specified demands depending on conditions of these materials functioning. Specific demand is its compatibility with liquid metals. Design of reactors with liquid-metal coolant (Li, PbLi 17 ) which reproduces tritium arise additional demand to structural materials. This demand is a creation of structural material or protective barrier with minimum acceptable value of tritium permeation through itself or with maximum permeation reduction factor (PRF). Vanadium and vanadium alloys are supposed to be use as a blanket structural material in such nuclear energy plants. Worked out at first stage of studies vanadium coatings should have stability of its characteristics at temperature 800 deg. C under influence of hydrogen. Given work shows the experimental results on testing of protective coatings over vanadium: glass-ceramic coating and CaO-base coating. PRF for every coating and its changes depending on thermo-capacity of vanadium sample with coating was determined by method of hydrogen permeation. The results of experiments would be used at the development of cooling loops of reactor core protection with liquid-metal coolant

  13. Effect of organic additives on positive electrolyte for vanadium redox battery

    International Nuclear Information System (INIS)

    Li Sha; Huang Kelong; Liu Suqin; Fang Dong; Wu Xiongwei; Lu Dan; Wu Tao

    2011-01-01

    Highlights: → Four organics as electrolyte additives of vanadium redox battery. → Changes are examined in the electrochemical properties of vanadium redox battery. → D-sorbitol is a suitable additive to the electrolyte for the vanadium redox battery. → The mechanism of improvement is discussed in detail. - Abstract: Fructose, mannitol, glucose, D-sorbitol are explored as additives in electrolyte for vanadium redox battery (VRB), respectively. The effects of additives on electrolyte are studied by cyclic voltammetry (CV), charge-discharge technique, electrochemical impedance spectroscopy (EIS) and Raman spectroscopy. The results indicate that the vanadium redox cell using the electrolyte with the additive of D-sorbitol exhibits the best electrochemical performance (the energy efficiency 81.8%). The EIS results indicate that the electrochemical activity of the electrolyte is improved by adding D-sorbitol, which can be interpreted as the increase of available (-OH) groups providing active sites for electron transfer. The Raman spectra show that VO 2+ ions take part in forming a complex with the D-sorbitol, which not only improve solubility of V(V) electrolyte, but also provide more activity sites for the V(IV)/V(V) redox reaction.

  14. Novel Vanadium-Loaded Ordered Collagen Scaffold Promotes Osteochondral Differentiation of Bone Marrow Progenitor Cells

    Directory of Open Access Journals (Sweden)

    Ana M. Cortizo

    2016-01-01

    Full Text Available Bone and cartilage regeneration can be improved by designing a functionalized biomaterial that includes bioactive drugs in a biocompatible and biodegradable scaffold. Based on our previous studies, we designed a vanadium-loaded collagen scaffold for osteochondral tissue engineering. Collagen-vanadium loaded scaffolds were characterized by SEM, FTIR, and permeability studies. Rat bone marrow progenitor cells were plated on collagen or vanadium-loaded membranes to evaluate differences in cell attachment, growth and osteogenic or chondrocytic differentiation. The potential cytotoxicity of the scaffolds was assessed by the MTT assay and by evaluation of morphological changes in cultured RAW 264.7 macrophages. Our results show that loading of VOAsc did not alter the grooved ordered structure of the collagen membrane although it increased membrane permeability, suggesting a more open structure. The VOAsc was released to the media, suggesting diffusion-controlled drug release. Vanadium-loaded membranes proved to be a better substratum than C0 for all evaluated aspects of BMPC biocompatibility (adhesion, growth, and osteoblastic and chondrocytic differentiation. In addition, there was no detectable effect of collagen or vanadium-loaded scaffolds on macrophage viability or cytotoxicity. Based on these findings, we have developed a new ordered collagen scaffold loaded with VOAsc that shows potential for osteochondral tissue engineering.

  15. Electromigration of hydrogen and deuterium in vanadium and niobium by a resistance method

    International Nuclear Information System (INIS)

    Peterson, D.T.; Jensen, C.L.

    1978-01-01

    The electric mobility of hydrogen and deuterium has been measured at 30 0 C in niobium (Cb) and vanadium by a resistance method. The electric mobility was found to be 5.7 x 10 -4 cm 2 /V-s for hydrogen and 2.8 x 10 -4 for deuterium in niobium. In vanadium the electric mobilities were 2.3 x 10 -3 and 1.3 x 10 -3 cm 2 /V-s for hydrogen and deuterium, respectively. The effective charges calculated using reported diffusion coefficients are positive and are slightly greater for deuterium than for hydrogen in both vanadium and niobium. The resistivity increase due to the hydrogen isotopes in vanadium and niobium was also measured. Hydrogen was found to contribute 0.65 μ ohm-cm/at. % and deuterium 0.58 μ ohm-cm/at. % to the resistivity of niobium. In vanadium, the solute resistivities were found to be 0.98 μ ohm-cm/at. % and 0.90 μ ohm-cm/at. % for hydrogen and deuterium, respectively

  16. Modeling of ion transport through a porous separator in vanadium redox flow batteries

    Science.gov (United States)

    Zhou, X. L.; Zhao, T. S.; An, L.; Zeng, Y. K.; Wei, L.

    2016-09-01

    In this work, we develop a two-dimensional, transient model to investigate the mechanisms of ion-transport through a porous separator in VRFBs and their effects on battery performance. Commercial-available separators with pore sizes of around 45 nm are particularly investigated and effects of key separator design parameters and operation modes are explored. We reveal that: i) the transport mechanism of vanadium-ion crossover through available separators is predominated by convection; ii) reducing the pore size below 15 nm effectively minimizes the convection-driven vanadium-ion crossover, while further reduction in migration- and diffusion-driven vanadium-ion crossover can be achieved only when the pore size is reduced to the level close to the sizes of vanadium ions; and iii) operation modes that can affect the pressure at the separator/electrode interface, such as the electrolyte flow rate, exert a significant influence on the vanadium-ion crossover rate through the available separators, indicating that it is critically important to equalize the pressure on each half-cell of a power pack in practical applications.

  17. Balancing Osmotic Pressure of Electrolytes for Nanoporous Membrane Vanadium Redox Flow Battery with a Draw Solute.

    Science.gov (United States)

    Yan, Ligen; Li, Dan; Li, Shuaiqiang; Xu, Zhi; Dong, Junhang; Jing, Wenheng; Xing, Weihong

    2016-12-28

    Vanadium redox flow batteries with nanoporous membranes (VRFBNM) have been demonstrated to be good energy storage devices. Yet the capacity decay due to permeation of vanadium and water makes their commercialization very difficult. Inspired by the forward osmosis (FO) mechanism, the VRFBNM battery capacity decrease was alleviated by adding a soluble draw solute (e.g., 2-methylimidazole) into the catholyte, which can counterbalance the osmotic pressure between the positive and negative half-cell. No change of the electrolyte volume has been observed after VRFBNM being operated for 55 h, revealing that the permeation of water and vanadium ions was effectively limited. Consequently, the Coulombic efficiency (CE) of nanoporous TiO 2 vanadium redox flow battery (VRFB) was enhanced from 93.5% to 95.3%, meanwhile, its capacity decay was significantly suppressed from 60.7% to 27.5% upon the addition of soluble draw solute. Moreover, the energy capacity of the VRFBNM was noticeably improved from 297.0 to 406.4 mAh remarkably. These results indicate balancing the osmotic pressure via the addition of draw solute can restrict pressure-dependent vanadium permeation and it can be established as a promising method for up-scaling VRFBNM application.

  18. Effect of vanadium doping on structural and magnetic properties of defective nano-nickel ferrite

    Science.gov (United States)

    Heiba, Zein K.; Mohamed, Mohamed Bakr; Wahba, Adel Maher; Almalowi, M. I.

    2018-04-01

    Nano-nickel ferrites defected by vanadium doping (NiV x Fe2-1.67 x O4, 0 ≤ x ≤ 0.25) were prepared using a simple sol gel method. Rietveld analysis revealed a nonmonotonic change in lattice parameter, oxygen parameter and magnetization upon doping with vanadium. Cation distributions suggested from either Rietveld analysis or from experimental magnetic moments were in a good agreement. For low doping values ( x = 0.05), vanadium was residing mainly in octahedral sites, while for samples with vanadium content ( x ≥ 0.1) a significant part of vanadium ions resided at tetrahedral sites; a result which has been confirmed by the analysis of Fourier-transform infrared (FTIR) spectrums obtained for the samples. The transmission electron microscope (TEM) image showed fine spherical particles with size of ˜ 11 nm. All samples showed a superparamagnetic nature with a nonmonotonic change of either magnetization ( M S) or coercivity (H C) with the content of nonmagnetic V5+. The cation occupancies indicated presence of an enormous number of vacancies through doping with high valence cation V5+, making present samples potential electrodes for Li- or Na-ion batteries.

  19. Atomistic simulation of hydrogen dynamics near dislocations in vanadium hydrides

    International Nuclear Information System (INIS)

    Ogawa, Hiroshi

    2015-01-01

    Highlights: • Hydrogen–dislocation interaction was simulated by molecular dynamics method. • Different distribution of H atoms were observed at edge and screw dislocation. • Planner distribution of hydrogen may be caused by partialized edge dislocation. • Hydrogen diffusivity was reduced in both edge and screw dislocation models. • Pipe diffusion was observed for edge dislocation but not for screw dislocation. - Abstract: Kinetics of interstitial hydrogen atoms near dislocation cores were analyzed by atomistic simulation. Classical molecular dynamics method was applied to model structures of edge and screw dislocations in α-phase vanadium hydride. Simulation showed that hydrogen atoms aggregate near dislocation cores. The spatial distribution of hydrogen has a planner shape at edge dislocation due to dislocation partialization, and a cylindrical shape at screw dislocation. Simulated self-diffusion coefficients of hydrogen atoms in dislocation models were a half- to one-order lower than that of dislocation-free model. Arrhenius plot of self-diffusivity showed slightly different activation energies for edge and screw dislocations. Directional dependency of hydrogen diffusion near dislocation showed high and low diffusivity along edge and screw dislocation lines, respectively, hence so called ‘pipe diffusion’ possibly occur at edge dislocation but does not at screw dislocation

  20. Structural and toxic effect investigation of vanadium pentoxide

    Energy Technology Data Exchange (ETDEWEB)

    Yuvakkumar, R., E-mail: yuvakkumar@gmail.com [Nanomaterials Laboratory, Department of Physics, Alagappa University, Karaikudi 630 004, Tamil Nadu (India); Department of Nanomaterials Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Hong, S.I., E-mail: sihong@cnu.ac.kr [Department of Nanomaterials Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

    2016-08-01

    A facile inorganic complex synthesis route has been developed to synthesis V{sub 2}O{sub 5} nanostructures. The effects of varying incubation time on the crystallinity and morphology of the V{sub 2}O{sub 5} phase has been investigated. The obtained XRD result clearly revealed the pure orthorhombic V{sub 2}O{sub 5} crystalline phase. Raman antiphase bridging V−O and chaining V−O stretching modes peaks at 686 and 521 cm{sup −1} attributed orthorhombic V{sub 2}O{sub 5} characteristics. The V2{sub p3/2} peak at the binding energies of 517 eV and V2{sub p1/2} peak at 524 eV assigned to V{sup 5+} oxidation state. Bioinspired V{sub 2}O{sub 5} nanostructures as a biocompatible material for anticancer agents show excellent cytotoxicity at higher V{sub 2}O{sub 5} concentration. - Highlights: • Sustainable and eco-friendly approach of vanadium pentoxide formation • Excellent cytotoxicity at higher V{sub 2}O{sub 5} concentration • Varying incubation on V{sub 2}O{sub 5} crystallinity and morphology was investigated.