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Sample records for wo sasaeru kiban

  1. Intelligent social infrastructure technology. Infrastructure technology support ultra-reliable society; Chiteki shakai kiban kogaku gijutsu. Choanshin shakai wo sasaeru kiban gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-01

    This survey was conducted to construct the core of intelligent social infrastructure technology (ISIT), and to investigate its practical application to industries and society. For realizing the ultra-safe and ultra-reliable society, it is necessary to develop the ISIT which can integrate various social infrastructures, such as architecture, city, energy, and lifeline systems required for living. For the systematization of cities, it is necessary to process and control the intelligent information by holding integrated and transverse information in common, as to logistics, lifeline, communication, monitoring, and control. For the communication engineering, the centralized systems are acceleratingly to be converted into the distributed network systems. For the mechanical engineering, intelligent control and robot technology are required. For the architectural engineering, a concept exceeding the conventional antiseismic structure idea is investigated. It is necessary to develop a new information technology providing an intelligent social infrastructures by merging the information networks and the physical world seamlessly. Necessity of ISIT is large for constructing the intelligent and ultra-reliable society consisting of these integrated and organized networks. 84 refs., 68 figs., 6 tabs.

  2. CAE to support a part of supporting technologies-its applications and verifying samples. Shien gijutsu no ittan wo sasaeru CAE sono torikumi to kensho rei

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, H. (Polyplastic Co. Ltd., Tokyo (Japan))

    1992-01-01

    Plastic CAE has suddenly being widened their applicable fields recently. On the other hand, since integated program development has also been made worldwidely, currently it is posssible to execute even for shrinkings and warping and warping analysis based on holding pressure analysis and cooling analysis. Polyplastics Company Inc. has paid attention to the usefullness of CAE technologies for engineering plastics from the early times, and in order to utilized them effectively, they have progressed several examinations on CAE software development, improvement of CAE analysis technologies, confirmation and verification of CAE analysis precision, resin data preparations and measuring methods, etc. In this paper, their applications have been introduced mainly by their verification samples such as output sample of FACE-2, which is their originally developped metal mold temperature adjustment design supporting system, and as for verification samples of warping deformation analysis, experimental result of testing metal mold (box type), and reliabilities on the results of measured precision and quantitative analysis of resin data to be used for analysis. 6 refs., 6 figs., 1 tab.

  3. Microalgal biotechnologies for recycling of pollutants; Tayona sorui kino wo kiban to suru seibutsuken busshitsu junkangata sogo saishigenka gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, K; Nasu, M; Hashimoto, C; Tanaka, K; Hirata, M [Osaka University, Osaka (Japan). Faculty of Pharmaceutial Science; Fujita, M; Takagi, M [Osaka University, Osaka (Japan). Faculty of Engineering; Hirata, Y; Taya, M [Osaka University, Osaka (Japan). Faculty of Engineering Science; Yamanishi, H [Osaka University, Osaka (Japan). Faculty of Medicine

    1997-02-01

    This paper describes the technology development by which biomass is produced by treatment of pollutants using microalgae, and is recycled. A bioreactor system has been developed, in which microalgal biomass can be obtained through the effective treatment of CO2 and NOx using microalgae having ability of increase under the severe condition with simultaneous flow of CO2 and NOx. A new method has been also developed for separating and recovering the microalgae. Materials, such as glucose, glycerol, acetic acid, and lactic acid, were produced from the obtained biomass through physico-chemical and biological treatments. These materials can be converted into ethanol and hydrogen. For this treatment and recycling system, functions as a part of natural material recycling were considered to be most significant. Development of an analysis and evaluation method of an impact of this system on the natural environment is also tried. 1 fig.

  4. Improved Charge Separation in WO3/CuWO4 Composite Photoanodes for Photoelectrochemical Water Oxidation

    Directory of Open Access Journals (Sweden)

    Danping Wang

    2016-05-01

    Full Text Available Porous tungsten oxide/copper tungstate (WO3/CuWO4 composite thin films were fabricated via a facile in situ conversion method, with a polymer templating strategy. Copper nitrate (Cu(NO32 solution with the copolymer surfactant Pluronic®F-127 (Sigma-Aldrich, St. Louis, MO, USA, generic name, poloxamer 407 was loaded onto WO3 substrates by programmed dip coating, followed by heat treatment in air at 550 °C. The Cu2+ reacted with the WO3 substrate to form the CuWO4 compound. The composite WO3/CuWO4 thin films demonstrated improved photoelectrochemical (PEC performance over WO3 and CuWO4 single phase photoanodes. The factors of light absorption and charge separation efficiency of the composite and two single phase films were investigated to understand the reasons for the PEC enhancement of WO3/CuWO4 composite thin films. The photocurrent was generated from water splitting as confirmed by hydrogen and oxygen gas evolution, and Faradic efficiency was calculated based on the amount of H2 produced. This work provides a low-cost and controllable method to prepare WO3-metal tungstate composite thin films, and also helps to deepen the understanding of charge transfer in WO3/CuWO4 heterojunction.

  5. Microwave mediated synthesis of nanostructured Co -WO_3 and CoWO_4 for supercapacitor applications

    International Nuclear Information System (INIS)

    Dhilip Kumar, R.; Karuppuchamy, S.

    2016-01-01

    Co-WO_3 and CoWO_4 nanopowders have been successfully obtained from microwave mediated process. The characterization of the prepared nanopowders was carried out by X-ray diffraction (XRD), scanning electron microscopy and Energy dispersive X-ray spectroscopy techniques. The XRD pattern confirms the formation of orthorhombic and monoclinic phase of the as-synthesized and calcined samples, respectively. Scanning electron microscopic examination of the resultant powders reveals the formation of nanoporous morphology. The electrochemical performance of the Co-WO_3 and CoWO_4 coated electrodes was also investigated. The maximum specific capacitance of 45 F/g was achieved for the Co-WO_3 nanopowder. - Highlights: • Novel nano-sized Co-WO_3 and CoWO_4 materials have been prepared. • A new and simple solution growth technique was developed. • Co-WO_3 is a promising material for supercapacitor applications.

  6. Phase diagrams of KY(WO4)2-KEr(WO4)2, KGd(WO4)2-KEr(WO4)2 systems and single crystal growth for some tungstates

    International Nuclear Information System (INIS)

    Yudanova, L.I.; Pavlyuk, A.A.; Potapova, O.G.

    1992-01-01

    Phase diagrams of the KY(WO 4 ) 2 -KEr(WO 4 ) 2 , KGd(WO 4 ) 2 -KEr(WO 4 ) 2 systems were studied by differential thermal and X-ray diffraction analyses. Continuous variety of solid solutions are in the KY(WO 4 ) 2 -KEr(WO 4 ) 2 system. They occurred just as in the area of alphaso beta-modifications. Limited areas of the solid solutions based on components were in the KGd(WO 4 ) 2 -KEr(WO 4 ) 2 system. Monocrystals of potassium-yttrium and potassium-gadolinium tungstates activated by erbium were grown using modified low-gradient Czochralski method

  7. Crossflow type silicon microchannel substrate monodispersion oil-in-water emulsion manufacture; Kurosufuro gata shirikon maikuro chaneru kiban wo mochiita tanbunsan suchuyu emarushon no sakusei

    Energy Technology Data Exchange (ETDEWEB)

    Kawakatsu, Takahiro [Tohoku University, Miyagi (Japan). Graduate School; Komori, Hideai; Najima, Mitsutashi; Kikuchi, Yuji; Yonemoto, Toshikuni

    1999-05-05

    The new technique, which continuously produced the monodispersion oil-in-water (0/W) emulsion using the crossflow type silicon microchannel substrate, was developed. On the silicon monocrystal substrate, the watercourse as the liquid of the continuous phase flowed was produced, and the column of the equal slit of the size in both walls of the watercourse was precisely processed. By closing the upper part in the slit by the clamp of the flat glass board in the microchannel substrate, the microchannel column was formed. Through the microchannel, the oil droplet in which the size was even was formed by sending out the oil (triolein) in the water (0.3wt% sodium lauryl sulfate aqueous solution) of continuous phase which is flowing in respect of the watercourse. The size of the oil droplet is greatly dependent on the structure of the microchannel regulated by microchannel width, microchannel height and terrace length (the even part of which the microchannel exit was equipped). Monodispersion emulsion of 16,20 and 48 {mu}m at the average droplet diameter was formed by using microchannel substrate of the three types of which the structure differs. Droplet diameter decreased, when the substrate which formed large droplet of 48 {mu}m in which the water current quantity is 1.4x10{sup -2}mLmin{sup -1} was used, when the flow rate increased. However, there was no a flow rate at droplet diameter, even if it was made to change from 1.4x10{sup -2} to 2.4mLmin{sup -1}, 16 {mu}m 20 {mu}m small change. In all cases, the droplet size distribution was narrow, and the geometry standard deviation was under 1.03. (translated by NEDO)

  8. FY1995 microalgal biotechnology for recycling of pollutants; 1995 nendo tayona sorui kino wo kiban to suru seibutsuken busshitsu junkangta sogo saishigenka gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    The objectives are 1) development of biological processes needed for the treatment of pollutants and the conversion of resulting biomass to value added products such as energy and fine chemicals, and 2) development of techniques for monitoring of both biological and chemical hazards associated with process operation. We developed a microalgal system for simultaneous removal of CO{sub 2}/NO{sub x} from flue gas, as well as an electro-osmotic method for recovery of microalgal cells. A strategy for effective culturing of photoautotrophic cells in photobioreactors was also proposed. We utilized waste algal biomass to produce biosurfactants, and studied about structure-function relationship of lipopeptide biosurfactants. As an energy product, H{sub 2} was produced via lactic acid fermentation of algal biomass. Physiology of marine phytoplankton was also studied in relation to the future mass production of microalgal biomass. A rapid monitoring of microbial populations was possible by using fluorescent probes. An enzyme immunosorbent assay system specific to fish metallothionein was established for the assessment of aquatic environmental pollution. Human herpesvirus latent infection was effectively applied to biological assay of environmental hygiene. (NEDO)

  9. Detection and phylogenetic analysis of bacteriophage WO in spiders (Araneae).

    Science.gov (United States)

    Yan, Qian; Qiao, Huping; Gao, Jin; Yun, Yueli; Liu, Fengxiang; Peng, Yu

    2015-11-01

    Phage WO is a bacteriophage found in Wolbachia. Herein, we represent the first phylogenetic study of WOs that infect spiders (Araneae). Seven species of spiders (Araneus alternidens, Nephila clavata, Hylyphantes graminicola, Prosoponoides sinensis, Pholcus crypticolens, Coleosoma octomaculatum, and Nurscia albofasciata) from six families were infected by Wolbachia and WO, followed by comprehensive sequence analysis. Interestingly, WO could be only detected Wolbachia-infected spiders. The relative infection rates of those seven species of spiders were 75, 100, 88.9, 100, 62.5, 72.7, and 100 %, respectively. Our results indicated that both Wolbachia and WO were found in three different body parts of N. clavata, and WO could be passed to the next generation of H. graminicola by vertical transmission. There were three different sequences for WO infected in A. alternidens and two different WO sequences from C. octomaculatum. Only one sequence of WO was found for the other five species of spiders. The discovered sequence of WO ranged from 239 to 311 bp. Phylogenetic tree was generated using maximum likelihood (ML) based on the orf7 gene sequences. According to the phylogenetic tree, WOs in N. clavata and H. graminicola were clustered in the same group. WOs from A. alternidens (WAlt1) and C. octomaculatum (WOct2) were closely related to another clade, whereas WO in P. sinensis was classified as a sole cluster.

  10. Nonlinear current-voltage characteristics of WO3-x nano-/micro-rods

    Science.gov (United States)

    Shen, Zhenguang; Peng, Zhijian; Zhao, Zengying; Fu, Xiuli

    2018-04-01

    A series of crystalline tungsten oxide nano-/micro-rods with different compositions of WO3, WO2.90, W19O55 (WO2.89) and W18O49 (WO2.72) but identical morphology feature were first prepared. Then, various nanoscaled electrical devices were fabricated from them by micro-fabrication through a focused ion beam technique. Interestingly, the devices from the oxygen-deficient WO3-x display significantly nonlinear current-voltage characteristics. The calculated nonlinear coefficients of the WO2.90, WO2.83, and WO2.72 varistors are 2.52, 3.32 and 4.91, respectively. The breakdown voltage of the WO2.90, WO2.83, and WO2.72 varistors are 1.93, 1.28 and 0.93 V, respectively. Such WO3-x nano-varistors might be promising for low-voltage electrical/electronic devices.

  11. Tuning the pure monoclinic phase of WO3 and WO3-Ag nanostructures for non-enzymatic glucose sensing application with theoretical insight from electronic structure simulations

    Science.gov (United States)

    Ponnusamy, Rajeswari; Gangan, Abhijeet; Chakraborty, Brahmananda; Sekhar Rout, Chandra

    2018-01-01

    Here, we report the controlled hydrothermal synthesis and tuning of the pure monoclinic phase of WO3 and WO3-Ag nanostructures. Comparative electrochemical nonenzymatic glucose sensing properties of WO3 and WO3-Ag were investigated by cyclic voltammetry and chronoamperometric tests. We observed enhanced glucose sensing performance of WO3-Ag porous spheres as compared to bare WO3 nanoslabs. The sensitivity of the pure WO3 nanoslabs is 11.1 μA μM-1 cm-2 whereas WO3-Ag porous spheres exhibit sensitivity of 23.3 μA μM-1 cm-2. The WO3-Ag porous spheres exhibited a good linear range (5-375 μM) with excellent anti-interference property. Our experimental observations are qualitatively supported by density functional theory simulations through investigation of bonding and charge transfer mechanism of glucose on WO3 and Ag doped WO3. As the binding energy of glucose is more on the Ag doped WO3 (100) surface compared to the bare WO3 (100) surface and the Ag doped WO3 (100) surface becomes more conducting due to enhancement of density of states near the Fermi level, we can infer that Ag doped WO3 exhibits a better charge transfer media compared to bare WO3 resulting in enhanced glucose sensitivity in consistency with our experimental data.

  12. A study of electron excitations in CaWO sub 4 and PbWO sub 4 single crystals

    CERN Document Server

    Muerk, V; Mihoková, E; Nitsch, K

    1997-01-01

    The excitation spectra of photo- and thermo-luminescence were compared in the VUV-UV spectral region in CaWO sub 4 and PbWO sub 4 scheelite tungstates. Temperature dependences of emission intensities and decay times were measured for PbWO sub 4 in the 80-300 K range and approximated by a simple phenomenological model. The energy level structure of the emission centre excited state and related kinetic processes are discussed for both tungstates. (author)

  13. In situ synthesis of CdS/CdWO4/WO3 heterojunction films with enhanced photoelectrochemical properties

    Science.gov (United States)

    Zhan, Faqi; Li, Jie; Li, Wenzhang; Yang, Yahui; Liu, Wenhua; Li, Yaomin

    2016-09-01

    CdS/CdWO4/WO3 heterojunction films on fluorine-doped tin oxide (FTO) substrates are for the first time prepared as an efficient photoanode for photoelectrochemical (PEC) hydrogen generation by an in situ conversion process. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet visible spectrometry (UV-vis) and X-ray photoelectron spectroscopy (XPS). The CdS hollow spheres (∼80 nm) sensitized WO3 plate film with a CdWO4 buffer-layer exhibits increased visible light absorption and a significantly improved photoelectrochemical performance. The photocurrent density at 0 V (vs. Ag/AgCl) of the CdS/CdWO4/WO3 anode is ∼3 times higher than that of the CdWO4/WO3 anode, and ∼9 times higher than that of pure WO3 under illumination. The highest incident-photon-to-current-efficiency (IPCE) value increased from 16% to 63% when the ternary heterojunction was formed. This study demonstrates that the synthesis of ternary composite photocatalysts by the in situ conversion process may be a promising approach to achieve high photoelectric conversion efficiency.

  14. Fabrication and characterization of WO3/Ag/WO3 multilayer transparent anode with solution-processed WO3 for polymer light-emitting diodes.

    Science.gov (United States)

    Jeon, Kangmin; Youn, Hongseok; Kim, Seongbeom; Shin, Seongbeom; Yang, Minyang

    2012-05-15

    The dielectric/metal/dielectric multilayer is suitable for a transparent electrode because of its high-optical and high-electrical properties; however, it is fabricated by an expensive and inefficient multistep vacuum process. We present a WO3/Ag/WO3 (WAW) multilayer transparent anode with solution-processed WO3 for polymer light-emitting diodes (PLEDs). This WAW multilayer not only has high transmittance and low resistance but also can be easily and rapidly fabricated. We devised a novel method to deposit a thin WO3 layer by a solution process in an air environment. A tungstic acid solution was prepared from an aqueous solution of Na2WO4 and then converted to WO3 nanoparticles (NPs) by a thermal treatment. Thin WO3 NP layers form WAW multilayer with a thermal-evaporated Ag layer, and they improve the transmittance of the WAW multilayer because of its high transmittance and refractive index. Moreover, the surface of the WO3 layer is homogeneous and flat with low roughness because of the WO3 NP generation from the tungstic acid solution without aggregation. We performed optical simulation and experiments, and the optimized WAW multilayer had a high transmittance of 85% with a sheet resistance of 4 Ω/sq. Finally, PLEDs based on the WAW multilayer anode achieved a maximum luminance of 35,550 cd/m2 at 8 V, and this result implies that the solution-processed WAW multilayer is appropriate for use as a transparent anode in PLEDs.

  15. Fiscal 1998 intellectual infrastructure project utilizing civil sector functions. Research and development project on prompt-effect type intellectual infrastructure creation (Basic study of measurement of human characteristics); 1998 nendo minkan no kino wo katsuyoshita chiteki kiban jigyo seika hokokusho. Sokkogata chiteki kiban sosei kenkyu kaihatsu jigyo (Ningen tokusei keisoku ni kansuru kiban kenkyu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    For the development of working conditions fit for aged people and devices for them to operate, their visual function and behavioral characteristics are measured and analyzed. In the study of visual functions, 50 people from local cities and regions and another 50 from Osaka and its neighboring cities are subjected to measurement regarding visual acuity required in daily life, color discrimination, dark adaptation, glare, and the like. In the study of performing characteristics, 500 people are subjected to measurement regarding the scope of movement of upper limbs, their reach, and skillfulness with which the people can move fingers. When brightness, luminance, and contrast are caused to change relative to letters and background, aging is found to exert a great influence on the ease of reading, dark adaptation, and glare. As for the upper limb work range and reachability and the skillfulness in finger movement, it is found that aging narrows down the tolerant work area, lowers the working pace, and greatly affects skillfulness depending on the device operating method, all these disclosing actualities of difference attributable to age and sex. Concerning the device operating position and the ease of device operating force application, new measuring and evaluating methods are worked out, and correlations between the contents of operation and the operating position are seized. (NEDO)

  16. Fiscal 1998 intellectual infrastructure project utilizing civil sector functions. Research and development project on prompt-effect type intellectual infrastructure creation (Buildup of base for thermophysical property data for new industry creation); 1998 nendo minkan no kino wo katsuyoshita chiteki kiban jigyo seika hokokusho. Sokkogata chiteki kiban sosei kenkyu kaihatsu jigyo (shinki sangyo sosei no tame no netsubussei data ni kansuru kiban seibi)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    For promoting the creation of new industries, thermophysical data on high-temperature molten bodies, liquid substances, solid materials, and the like were collected, and further measurements were performed; the data were stored in distributed databases; and databases were also developed about access to the Internet. In the study of the thermal properties of high-temperature molten bodies, data were collected from technical literature concerning molten silicon for semiconductor production, that is, 2 about thermal diffusivity, 4 about viscosity index, 30 about surface tension, 8 about density, and 6 about emissivity; and, concerning potassium niobate, 6 about density, 4 about surface tension, and 5 about viscosity index were collected. Thermal properties were measured for molten silicon and molten carbonates. In the study of thermal properties of fluids, data such as PVT (pressure, volume, temperature) values, boiling point pressure, saturated liquid density, isothermal compressibility, cubical expansion coefficient, surplus mol volume, and the like were collected again from technical literature concerning trifluoroethanol and its water solution. Thermodynamic properties of the aqueous ammonia solution comprised of equimolecules were measured. (NEDO)

  17. A study on properties of PbWO4 crystal

    International Nuclear Information System (INIS)

    He Jingtang; Mao Yufang; Dong Xiaoli

    1997-01-01

    The experimental results on properties of the PbWO 4 crystal are reported, including the excitation and fluorescence spectra, absolute and relative light yield and decay times. It seems that the PbWO 4 crystal can be used in high energy physics experiments for detecting high energy shower particles

  18. Intrinsic Defects and H Doping in WO3

    KAUST Repository

    Zhu, Jiajie; Vasilopoulou, Maria; Davazoglou, Dimitris; Kennou, Stella; Chroneos, Alexander; Schwingenschlö gl, Udo

    2017-01-01

    WO3 is widely used as industrial catalyst. Intrinsic and/or extrinsic defects can tune the electronic properties and extend applications to gas sensors and optoelectonics. However, H doping is a challenge to WO3, the relevant mechanisms being hardly

  19. The luminescence of CaWO4: Bi single crystals

    International Nuclear Information System (INIS)

    Zorenko, Yu.; Pashkovsky, M.; Voloshinovskii, A.; Kuklinski, B.; Grinberg, M.

    2006-01-01

    Influence of doping with Bi 3+ ions and Bi 3+ -Na + or Bi 3+ -Li + ions pairs on luminescence, emission kinetics and light yield of CaWO 4 crystals has been investigated. It has been shown that under excitation in the A-band at 272 and 287nm, related to the Bi 3+ ions absorption, the luminescence peaked at 468nm decaying with time τ=0.41μs is observed. For bismuth concentration 50-500ppm and the equimolar concentrations of the Bi 3+ ions accompanied by Na + or Li + ions compensators the significant suppression of the phosphorescence peaked at 520nm, related to the defect WO 3 -V O complex, and an improvement of scintillation characteristics of the CaWO 4 are noticed. Energy transfer from the defect WO 3 -V O and regular WO 4 2- oxy-anions to Bi 3+ ions have been observed at room temperatures and discussed

  20. Synthesis, Characterization, and Gas Sensing Applications of WO3 Nanobricks

    Science.gov (United States)

    Xiao, Jingkun; Song, Chengwen; Dong, Wei; Li, Chen; Yin, Yanyan; Zhang, Xiaoni; Song, Mingyan

    2015-08-01

    WO3 nanobricks are fabricated by a simple hydrothermal method. Morphology and structure of the WO3 nanobricks are characterized by scanning electron microscopy and x-ray diffraction. Gas sensing properties of the as-prepared WO3 sensor are systematically investigated by a static gas sensing system. The results show that the WO3 nanobricks with defect corners demonstrate good crystallinity, and the mean edge length and wall thickness are 1-1.5 and 400 nm, respectively. The WO3 sensor achieves its maximum sensitivity to 100 ppm ethanol at the optimal operating temperature of 300 °C. Ultra-fast response time (2-3 s) and fast recovery time (4-11 s) of the WO3 sensor toward 100 ppm ethanol are also observed at this optimal operating temperature. Moreover, the WO3 sensor exhibits high selectivity to other gases such as methanol, benzene, hexane, and dichloromethane, indicating its excellent potential application as a gas sensor for ethanol detection.

  1. An ultraviolet photodetector fabricated from WO3 nanodiscs/reduced graphene oxide composite material

    International Nuclear Information System (INIS)

    Shao Dali; Sawyer, Shayla; Yu Mingpeng; Lian Jie

    2013-01-01

    A high sensitivity, fast ultraviolet (UV) photodetector was fabricated from WO 3 nanodiscs (NDs)/reduced graphene oxide (RGO) composite material. The WO 3 NDs/reduced GO composite material was synthesized using a facile three-step synthesis procedure. First, the Na 2 WO 4 /GO precursor was synthesized by homogeneous precipitation. Second, the Na 2 WO 4 /GO precursor was transformed into H 2 WO 4 /GO composites by acidification. Finally, the H 2 WO 4 /GO composites were reduced to WO 3 NDs/RGO via a hydrothermal reduction process. The UV photodetector showed a fast transient response and high responsivity, which are attributed to the improved carrier transport and collection efficiency through graphene. The excellent material properties of the WO 3 NDs/RGO composite demonstrated in this work may open up new possibilities for using WO 3 NDs/RGO for future optoelectronic applications. (paper)

  2. Electrochromic device based on electrospun WO{sub 3} nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Dulgerbaki, Cigdem; Maslakci, Neslihan Nohut; Komur, Ali Ihsan; Oksuz, Aysegul Uygun, E-mail: ayseguluygun@sdu.edu.tr

    2015-12-15

    Highlights: • WO{sub 3} electrochromic nanofibers were prepared by electrospinning technique. • WO{sub 3} nanofibers switched reversibly from transparent to blue color. • Electrochromic device was assembled using ionic liquid based gel electrolyte. • Significant optical modulation and excellent cycling stability were achieved for ECD. - Abstract: The tungsten oxide (WO{sub 3}) nanofibers were grown directly onto an ITO-coated glass via an electrospinning method for electrochromic applications. The electrochromic properties of WO{sub 3} nanofibers were investigated in the presence of different electrolytes including a series of ionic liquids and classic LiClO{sub 4}-PC system. A significant optical modulation of 20.82% at 760 nm, reversible coloration with efficiency of 64.58 cm{sup 2}/C and excellent cycling stability were achieved for the nanofiber electrochromic device (ECD) with ionic liquid based gel electrolyte.

  3. SrWO4 at high pressures

    International Nuclear Information System (INIS)

    Grzechnik, A.; Crichton, W.A.; Hanfland, M.

    2005-01-01

    Room-temperature high-pressure behaviour of SrWO 4 scheelite (I4 1 /a, Z=4) has been studied to 20.7 GPa in a diamond anvil cell using synchrotron angle-dispersive X-ray powder diffraction. Above 10 GPa, it transforms to the fergusonite structure (I2/a, Z=4). Both scheelite and fergusonite types are ordered superstructures of fluorite (Fm anti 3m, Z=4). There is no significant volume collapse at the scheelite-fergusonite phase transition. However, the compression data including both phases of strontium tungstate cannot be fitted by a common Birch-Murnaghan equation of state. An onset of decomposition into component oxides occurs at about 15 GPa. The pressure-induced transformations are irreversible. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Hydrothermal synthesis of CdWO 4 nanorods and their ...

    African Journals Online (AJOL)

    CdWO4 nanorods with wolframite structure were synthesized in the presence of the surfactant SDBS by a hydrothermal method, and characterized by a variety of techniques. The obtained products are CdWO4 nanorods with length of 0.8–2.5 μm and width of 50–250 nm. The surfactant SDBS plays a key role in the ...

  5. Anti-tumor activity of self-charged (Eu,Ca):WO3 and Eu:CaWO4 nanoparticles

    International Nuclear Information System (INIS)

    Lin, Cao; Cong, Wang; De'An, Pan; Jiexin, Cao; Ping, Che; Volinsky, Alex A.

    2012-01-01

    Non-stoichiometric (Eu,Ca):WO 3 and Eu:CaWO 4 nanoparticles with anti-tumor activity are synthesized in a sol-gel method by adding excessive Eu 3+ and Ca 2+ ions to tungsten oxide crystal structure. Colorimetric assay shows that 10 nm (Eu,Ca):WO 3 and Eu:CaWO 4 nanoparticles can effectively inhibit growth of mammary cancer cells without any harm to normal cells. Nanoparticles are characterized by X-ray diffraction, high resolution transmission electron microscopy and fluorescence optical spectrometry. Nanomaterials, insoluble in synthesized water, have complicated self-charging surfaces that trap mammary cancer cells. Surface self-charging effect is suggested as the inhibition mechanism. (author)

  6. Conduction and transport numbers in metacomposites MeWO4 · WO3 (Me = Ca, Sr, Ba)

    International Nuclear Information System (INIS)

    Nejman, A.Ya.; Pestereva, N.N.; Sharafutdinov, A.R.; Kostikov, Yu.P.

    2005-01-01

    The conductivity and transfer numbers of charge carriers for composites in the MeWO 4 -WO 3 (Me = Ca, Sr, Ba) systems are studied as a function of the temperature and the activity of oxygen in a gas phase. The transfer numbers are determined by the emf method and are estimated from dependences of conductivity on the activity of oxygen in a gas phase. The deficiencies of the given procedure as applied to investigation of properties of composite phases are analyzed. The materials under study are classified as metacomposites. The concentration intervals of the ionic, mixed, and electronic conductivities are determined. The conductivity of (100-x)MeWO 4 · xWO 3 composites is predominantly ionic at x ≤ 10 (Me = Ca), x ≤ 60 (Me = Sr), and x ≤ 45 (Me = Ba). The obtained data are explained in the framework of a model that represents a composite as a distributed matrix system where a film of surface phase MeW-s with a high mobility of oxygen ions plays the role of a connected matrix. It is presumed that the surface phase MeW-s possesses double-sided surface activity (α MeW-s ≤ α WO 3 , α MeWO 4 ) and a higher mobility with respect to MeWO 4 and WO 3 . The discovered anomalies of dependences σ O 2- (T) and partial conductivities σ O 2- , σ el (T) are explained by a change in the stoichiometry, morphology, and the degree of tie-up of surface phase MeW-s caused by a change in the temperature and composition of composites [ru

  7. Photoluminescence in solid solutions and thin films of tungstates CaWO{sub 4}-CdWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Taoufyq, A.; Mauroy, V.; Guinneton, F.; Valmalette, J-C. [University of Toulon, IM2NP, UMR CNRS 7334, La Garde, (France); Fiorido, T. [Aix Marseille University, IM2NP, UMR CNRS, 7334, Marseille, (France); Benlhachemi, A. [IBN ZOHR University, Faculty of sciences, Environment and Materials Laboratory, Agadir, (Morocco); Lyoussi, A. [CEA of Cadarache, DEN, Departement of reactors studies, experimental physics, Instrumentation Sensors and Dosimetry Laboratory, (France); Nolibe, G. [Cesigma society, signals and systems, La Garde, (France); Gavarri, J-R. [University of Toulon, IM2NP, UMR CNRS 7334, La Garde, (France)

    2015-07-01

    In this study, we present two types of studies on the luminescence properties under UV and X-ray excitations of solid solutions Ca{sub 1-x}Cd{sub x}WO{sub 4} and of thin layers of CaWO{sub 4} and CdWO{sub 4}. These tungstate based solid solutions are susceptible to be integrated into new radiation sensors, in order to be used in different fields of applications such as reactor measurements, safeguards, homeland security, nuclear nondestructive assays, LINAC emission radiation measurement. However these complex materials were rarely investigated in the literature. One first objective of our studies was to establish correlations between luminescence efficiency, chemical substitution and the degree of crystallization resulting from elaboration conditions. A second objective will be to determine the efficiency of luminescence properties of thin layers of these materials. In the present work, we focus our attention on the role of chemical substitution on photon emissions under UV and X-ray irradiations. The luminescence spectra of Ca{sub 1-x}Cd{sub x}WO{sub 4} polycrystalline materials have been investigated at room temperature as a function of composition (0≤x≤1). In addition, we present a preliminary study of the luminescence of CaWO{sub 4} and CdWO{sub 4} thin layers: oscillations observed in the case of X-ray excitations in the luminescence spectra are discussed. (authors)

  8. In-situ transmission electron microscopy imaging of formation and evolution of LixWO3 during lithiation of WO3 nanowires

    International Nuclear Information System (INIS)

    Qi, Kuo; Li, Xiaomin; Sun, Muhua; Huang, Qianming; Wei, Jiake; Xu, Zhi; Wang, Wenlong; Bai, Xuedong; Wang, Enge

    2016-01-01

    The phase transition from monoclinic WO 3 to cubic Li x WO 3 during lithiation of WO 3 is one of the key features for tungsten oxide as the most used electrochromic material. Conventionally, the lithium intercalation of WO 3 has been studied by building generic layered electrochromic device combining with structural characterization and electrochemistry measurement at macro scale. In-situ transmission electron microscopy (in-situ TEM) has been proposed as a method for revealing the detailed mechanism of structural, physical, and chemical properties. Here, we use in-situ TEM method to investigate the formation and evolution of Li x WO 3 in real-time during the electrochemical lithiation of WO 3 nanowires. The dynamic lithiation process is recorded by TEM imaging, diffraction, and electron energy loss spectroscopy. The WO 3 -Li x WO 3 phase boundary of reaction front has been observed at high resolution. The timeliness of crystallinity of Li x WO 3 and the intercalation channels for Li ions are also identified. Moreover, the co-existence of both polycrystalline Li-poor area and amorphous Li-rich phases of Li x WO 3 was found. Our results provide an insight into the basic lithiation process of WO 3 , which is significantly important for understanding the electrochromic mechanism of tungsten oxide.

  9. Visible-light photocatalytic activity of graphene oxide-wrapped Bi2WO6 hierarchical microspheres

    Science.gov (United States)

    Zhai, Jiali; Yu, Hongwen; Li, Haiyan; Sun, Lei; Zhang, Kexin; Yang, Hongjun

    2015-07-01

    A facile approach of fabricating homogeneous graphene oxide (GO)-wrapped Bi2WO6 microspheres (GO/Bi2WO6) is developed. The transmission electron microscopy (TEM) results show that a heterojunction interface between GO and Bi2WO6. The UV-vis diffuse reflection spectra (DRS) reveal that the as-prepared GO/Bi2WO6 composites own more intensive absorption in the visible light range compared with pure Bi2WO6. These characteristic structural and optical properties endow GO/Bi2WO6 composites with enhanced photocatalytic activity. The enhanced photocatalytic activity of the GO/Bi2WO6 is attributed predominantly to the synergetic effect between GO and Bi2WO6, causing rapid generation and separation of photo-generated charge carriers.

  10. Structure and photocatalytic performance of layered HNbWO6 nanosheet aggregation

    KAUST Repository

    Hu, Li-Fang

    2015-12-10

    Layered HNbWO6HNbWO6 nanosheet aggregation (e-HNbWO6e-HNbWO6) has been assembled by HNbWO6HNbWO6 nanosheet via an exfoliation-restaking route. The as-prepared samples are characterized by means of powder x-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy, laser Raman spectroscopy, ultraviolet-vis diffuse reflectance spectroscopy, and N2N2 adsorption-desorption isotherms. The photocatalytic performances of the as-prepared samples are evaluated by degradation of methylene blue (MB). The results revealed that e-HNbWO6e-HNbWO6 has a specific surface area of about 156.5  m2 g−1156.5  m2 g−1, and exhibits a relatively excellent photocatalytic performance for degradation of MB under UV light.

  11. Structure and photocatalytic performance of layered HNbWO6 nanosheet aggregation

    KAUST Repository

    Hu, Li-Fang; Li, Rui; He, Jie; Da, Liang-guo; Lv, Wei; Hu, Jin-song

    2015-01-01

    Layered HNbWO6HNbWO6 nanosheet aggregation (e-HNbWO6e-HNbWO6) has been assembled by HNbWO6HNbWO6 nanosheet via an exfoliation-restaking route. The as-prepared samples are characterized by means of powder x-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy, laser Raman spectroscopy, ultraviolet-vis diffuse reflectance spectroscopy, and N2N2 adsorption-desorption isotherms. The photocatalytic performances of the as-prepared samples are evaluated by degradation of methylene blue (MB). The results revealed that e-HNbWO6e-HNbWO6 has a specific surface area of about 156.5  m2 g−1156.5  m2 g−1, and exhibits a relatively excellent photocatalytic performance for degradation of MB under UV light.

  12. Characterization of nanosized Al2(WO4)3

    International Nuclear Information System (INIS)

    Nihtianova, D.; Velichkova, N.; Nikolova, R.; Koseva, I.; Yordanova, A.; Nikolov, V.

    2011-01-01

    Graphical abstract: TEM method allows to detect small quantities of impurities not detectable by other methods. In our case impurities of W 5 O 14 are detected in Al 2 (WO 4 ) 3 nanopowder. Highlights: → Nanosized Al 2 (WO 4 ) 3 by simple co-precipitation method. → Spherical particles with mean size of 22 nm distributed between 10 and 40 nm at 630 o C. → XRD, DTA and TEM confirm well defined products with perfect structure. → TEM locality allows detection of impurities not detectable by XRD and DTA. -- Abstract: Nanosized aluminum tungstate Al 2 (WO 4 ) 3 was prepared by co-precipitation reaction between Na 2 WO 4 and Al(NO 3 ) 3 aqueous solutions. The powder size and shape, as well as size distribution are estimated after different conditions of powder preparation. The purity of the final product was investigated by XRD and DTA analyses, using the single crystal powder as reference. Between the specimen and the reference no difference was detected. The crystal structure of Al 2 (WO 4 ) 3 nanosized powder was confirmed by TEM (SAED, HRTEM). In additional, TEM locality allows to detect some W 5 O 14 impurities, which are not visible by conventional X-ray powder diffraction and thermal analyses.

  13. Correlations among structure, composition and electrochemical performances of WO3 anode materials for lithium ion batteries

    International Nuclear Information System (INIS)

    Li, Pu; Li, Xing; Zhao, Ziyan; Wang, Mingshan; Fox, Thomas; Zhang, Qian; Zhou, Ying

    2016-01-01

    Highlights: • The residual precursor ions affect the charge/discharge performances of WO 3 . • Lithiated monoclinic WO 3 reveals the best discharge capacity. • Lithiation can enhance the conductivity of WO 3 . - Abstract: Suitable host structure for lithium insertion and extraction is crucial for lithium-ion batteries. Tungsten trioxides (WO 3 ) are particularly interesting materials for this purpose. In this work, the influences of structure and composition of WO 3 on the charge/discharge performances of Li-ion batteries are systematically investigated. Firstly, lithiated tungsten trioxides (Li-WO 3 ) are successfully synthesized by a hydrothermal method followed by annealing at different temperatures (200–600 °C). It is found that the hexagonal framework collapses and gradually transforms to the monoclinic phase due to the release of NH 4 + and NH 3 molecules. Unexpectedly, monoclinic WO 3 reveals better performances than that of hexagonal WO 3 . Among all the investigated samples, the lithiated WO 3 annealed at 500 °C exhibits the highest discharge capacity and cycle performance (703 mAh g −1 after 10 cycles). We believe that the Li + remained in the solid structure of WO 3 can lead to a more stable structure. In addition, Li + could inhibit the oxidation of W 5+ during the heat treatment process, which increases the electron conductivity of WO 3 . Our results indicate that the electrochemical properties of WO 3 are strongly related to the residual precursor and crystal structure.

  14. Biomimetic fabrication of WO3 for water splitting under visible light with high performance

    International Nuclear Information System (INIS)

    Yin, Chao; Zhu, Shenmin; Yao, Fan; Gu, Jiajun; Zhang, Wang; Chen, Zhixin; Zhang, Di

    2013-01-01

    Inspired by the high light-harvesting properties of typical butterfly wings, ceramic WO 3 butterfly wings with hierarchical structures of bio-butterfly wings was fabricated using a template of PapilioParis butterfly wings through a sol–gel method. The effect of calcination temperatures on the structures of the ceramic butterfly wings was investigated and the results showed that the WO 3 butterfly wing replica calcined at 550 °C (WO 3 replica-550) is a single phase and has a high crystallinity and relatively fine hierarchical structure. The average grain size of WO 3 replica-550 and WO 3 powder are around 32.6 and 42.2 nm, respectively. Compared with pure WO 3 powder, WO 3 replica-550 demonstrated a higher light-harvesting capability in the region from 460 to 700 nm and more importantly the higher charge separation rate, as evidenced by electron paramagnetic resonance measurements. Photocatalytic O 2 evolutions from water were investigated on the ceramic butterfly wings and pure WO 3 powder under visible light (λ > 420 nm). The results showed that the amount of O 2 produced from WO 3 replica-550 is 50 % higher than that of the pure WO 3 powder. The improved photocatalytic performance of WO 3 replica-550 is attributed to the quasi-honeycomb structure inherited from the PapilioParis butterfly wings, providing both high light-harvesting efficiency and efficient charge transport through the WO 3

  15. X-ray photoelectron spectroscopy study of BaWO{sub 4} and Ba{sub 2}CaWO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Capece, Angela M., E-mail: acapece@pppl.gov [California Institute of Technology, Pasadena, CA (United States); Polk, James E. [Jet Propulsion Laboratory, Pasadena, CA (United States); Shepherd, Joseph E. [California Institute of Technology, Pasadena, CA (United States)

    2014-12-15

    Highlights: • XPS reference spectra for Ba{sub 2}CaWO{sub 6} and BaWO{sub 4} are presented. • Binding energies of Ba 3d and W 4f lines are 0.7 eV higher for BaWO{sub 4} than Ba{sub 2}CaWO{sub 6}. • Ca 2p spectrum contains two sets of Ca 2p doublets attributed to Ba{sub 2}CaWO{sub 6} and CaCO{sub 3}. - Abstract: XPS reference spectra for Ba{sub 2}CaWO{sub 6} and BaWO{sub 4} are presented, including high resolution spectra of the Ba 3d, W 4f, C 1s, Ca 2p, and O 1s lines. The peak locations and full widths at half maximum are also given. The binding energies of the Ba 3d and W 4f lines are 0.7 eV higher for BaWO{sub 4} than for Ba{sub 2}CaWO{sub 6}. The Ca 2p spectrum contains two sets of Ca 2p doublets that were attributed to Ba{sub 2}CaWO{sub 6} and CaCO{sub 3}.

  16. Intrinsic Defects and H Doping in WO3

    KAUST Repository

    Zhu, Jiajie

    2017-01-18

    WO3 is widely used as industrial catalyst. Intrinsic and/or extrinsic defects can tune the electronic properties and extend applications to gas sensors and optoelectonics. However, H doping is a challenge to WO3, the relevant mechanisms being hardly understood. In this context, we investigate intrinsic defects and H doping by density functional theory and experiments. Formation energies are calculated to determine the lowest energy defect states. O vacancies turn out to be stable in O-poor environment, in agreement with X-ray photoelectron spectroscopy, and O-H bond formation of H interstitial defects is predicted and confirmed by Fourier transform infrared spectroscopy.

  17. Facile Hydrogen Evolution Reaction on WO3Nanorods

    Directory of Open Access Journals (Sweden)

    Rajeswari Janarthanan

    2007-01-01

    Full Text Available AbstractTungsten trioxide nanorods have been generated by the thermal decomposition (450 °C of tetrabutylammonium decatungstate. The synthesized tungsten trioxide (WO3 nanorods have been characterized by XRD, Raman, SEM, TEM, HRTEM and cyclic voltammetry. High resolution transmission electron microscopy and X-ray diffraction analysis showed that the synthesized WO3nanorods are crystalline in nature with monoclinic structure. The electrochemical experiments showed that they constitute a better electrocatalytic system for hydrogen evolution reaction in acid medium compared to their bulk counterpart.

  18. Optical and electrochromic properties of Sn:WO3 cermets

    International Nuclear Information System (INIS)

    Ashrit, P.V.; Bader, G.; Girouard, F.E.; Truong, V.V.

    1989-01-01

    This paper discusses optical and electrochromic properties of Sn:WO 3 cermets deposited by alternate layer thermal deposition. These cermets exhibit electrical and optical behavior in the as deposited state. The inclusion of Sn in the WO 3 matrix enhances the Electrical conductivity of the system and renders them fairly transparent in the visible region. The electrochromic behavior of such systems is studied under both proton and Li + ion injection. The good conductivity and good transmission combined with good electrochromic characteristics of these systems indicate the possibility of utilizing this type of cermet for the dual role of transparent conductor (TC) and electrochromic (EC) layer

  19. Structure, electrochromic and optical properties of WO3 film prepared by dip coating-pyrolysis

    International Nuclear Information System (INIS)

    Yang Haitao; Shang Fuliang; Gao Ling; Han Haitao

    2007-01-01

    The tungsten oxide (WO 3 ) film was grown by dip coating-pyrolysis method with the PEG-400 as the structure-directing agent. Microstructure of the WO 3 film was characterized by TG-DSC, XRD and SEM techniques. It was found that the film annealed at 350 deg. C for 2 h comprised cubic WO 3 and orthorhombic WO 3 . The measurements of the cyclic voltammetry (CV) and UV-vis spectrum suggested that the WO 3 film had a good electrochromic reversibility performance. The film possessed excellent modulation to the visible light and the maximal average transmittance modulation reached 70.06%

  20. Photocatalytic activity of Bi_2WO_6/Bi_2S_3 heterojunctions: the facilitation of exposed facets of Bi_2WO_6 substrate

    International Nuclear Information System (INIS)

    Yan, Long; Wang, Yufei; Shen, Huidong; Zhang, Yu; Li, Jian; Wang, Danjun

    2017-01-01

    Highlights: • Bi_2S_3/Bi_2WO_6 hybrids with exposed (020) Bi_2WO_6 facets have been synthesized. • X-ray photoelectron spectroscopy reveals that a small amount of Bi_2S_3 was formed. • The enhanced photoactivity of hybrids is due to heterojunction and (020) facets. • A possible photocatalytic degradation mechanism is proposed. - Abstract: Bi_2S_3/Bi_2WO_6 hybrid architectures with exposed (020) Bi_2WO_6 facets have been synthesized via a controlled anion exchange approach. X-ray photoelectron spectroscopy (XPS) reveals that a small amount of Bi_2S_3 was formed on the surface of Bi_2WO_6 during the anion exchange process, thus leading to the transformation from the Bi_2WO_6 to Bi_2S_3/Bi_2WO_6. A rhodamine B (RhB) aqueous solution was chosen as model organic pollutants to evaluate the photocatalytic activities of the Bi_2S_3/Bi_2WO_6 catalysts. Under visible light irradiation, the Bi_2S_3/Bi_2WO_6-TAA displayed the excellent visible light photoactivities compared with pure Bi_2S_3, Bi_2WO_6 and other composite photocatalysts. The efficient photocatalytic activity of the Bi_2S_3/Bi_2WO_6-TAA composite microspheres was ascribed to the constructed heterojunctions and the inner electric field caused by the exposed (020) Bi_2WO_6 facets. Active species trapping experiments revealed that h"+ and O_2·"− are the main active species in the photocatalytic process. Furthermore, the as-obtained photocatalysts showed good photocatalytic activity after four recycles. The results presented in this study provide a new concept for the rational design and development of highly efficient photocatalysts.

  1. Cr2O3 nanoparticle-functionalized WO3 nanorods for ethanol gas sensors

    Science.gov (United States)

    Choi, Seungbok; Bonyani, Maryam; Sun, Gun-Joo; Lee, Jae Kyung; Hyun, Soong Keun; Lee, Chongmu

    2018-02-01

    Pristine WO3 nanorods and Cr2O3-functionalized WO3 nanorods were synthesized by the thermal evaporation of WO3 powder in an oxidizing atmosphere, followed by spin-coating of the nanowires with Cr2O3 nanoparticles and thermal annealing in an oxidizing atmosphere. Scanning electron microscopy was used to examine the morphological features and X-ray diffraction was used to study the crystallinity and phase formation of the synthesized nanorods. Gas sensing tests were performed at different temperatures in the presence of test gases (ethanol, acetone, CO, benzene and toluene). The Cr2O3-functionalized WO3 nanorods sensor showed a stronger response to these gases relative to the pristine WO3 nanorod sensor. In particular, the response of the Cr2O3-functionalized WO3 nanorods sensor to 200 ppm ethanol gas was 5.58, which is approximately 4.4 times higher that of the pristine WO3 nanorods sensor. Furthermore, the Cr2O3-functionalized WO3 nanorods sensor had a shorter response and recovery time. The pristine WO3 nanorods had no selectivity toward ethanol gas, whereas the Cr2O3-functionalized WO3 nanorods sensor showed good selectivity toward ethanol. The gas sensing mechanism of the Cr2O3-functionalized WO3 nanorods sensor toward ethanol is discussed in detail.

  2. Detailed explanation of organizations and systems of the U.S. Federal Government supporting R and D systems in the U.S. Supplement: New trends of strategies of technology development/acquisition/commercialization of private companies in the U.S.; Beikoku no R and D system wo sasaeru renpo seifu soshiki oyobi seido no shosai kaisetsu. Furoku (Beikoku minkan kigyo no kaihatsu shutoku shogyoka senryaku no shinchoryu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    Explanation was made in detail of systems of the U.S. Federal Government which are useful when NEDO and the Japanese government improve/reform R and D supporting systems in future. Grant is in use for supporting researches conducted by universities, nonprofit organizations, etc. mostly in the field of the basic research. This is a research fund very high in freedom and easy for Grant recipients to handle. Contract, recipients of which are mostly private companies, is used for the system development rather than the basic research. In either system, if there is a possibility of producing any merits as a result of the implementation of the R and D project, the government may sometimes ask the recipient such as university to pay part of the cost. As an intermediate form between both mechanisms, a lot of mechanisms are used in which the government/universities/private companies share the cost, responsibility, results, etc. as partners. These are joint agreements, joint research contracts and alternative contracts. (NEDO)

  3. Faster response of NO2 sensing in graphene–WO3 nanocomposites

    International Nuclear Information System (INIS)

    Srivastava, Shubhda; Jain, Kiran; Gupta, Govind; Senguttuvan, T D; Singh, V N; Singh, Sukhvir; Vijayan, N; Dilawar, Nita

    2012-01-01

    Graphene-based nanocomposites have proven to be very promising materials for gas sensing applications. In this paper, we present a general approach for the preparation of graphene–WO 3 nanocomposites. Graphene–WO 3 nanocomposite thin-layer sensors were prepared by drop coating the dispersed solution onto the alumina substrate. These nanocomposites were used for the detection of NO 2 for the first time. TEM micrographs revealed that WO 3 nanoparticles were well distributed on graphene nanosheets. Three different compositions (0.2, 0.5 and 0.1 wt%) of graphene with WO 3 were used for the gas sensing measurements. It was observed that the sensor response to NO 2 increased nearly three times in the case of graphene–WO 3 nanocomposite layer as compared to a pure WO 3 layer at room temperature. The best response of the graphene–WO 3 nanocomposite was obtained at 250 °C. (paper)

  4. Structure of the short-range atomic order of WO3 amorphous films

    International Nuclear Information System (INIS)

    Olevskij, S.S.; Sergeev, M.S.; Tolstikhina, A.L.; Avilov, A.S.; Shkornyakov, S.M.; Semiletov, S.A.

    1984-01-01

    To study the causes of electrochromism manifestation in thin tungsten oxide films, the structure of WO 3 amorphous films has been investigated. The films were obtained by three different methods: by W(CO) 6 tungsten carbonyl pyrolysis, by high-frequency ion-plasma sputtering of a target prepared by WO 3 powder sintering, and by WO 3 powder thermal evaporation. Monocrystalline wafers of silicon and sodium chloride were used as substrates. The structure of short-range order in WO 3 amorphous films varies versus, the method of preparation in compliance with the type of polyhedral elements, (WO 6 , WO 5 ) and with the character of their packing (contacts via edges or vertices). Manifestation of electroc ro mism in WO 3 films prepared by varions methods and having different structure of short-range order is supposed to be realized through various mechanisms. One cannot exclude a potential simultaneous effect of the two coloration mechanisms

  5. Electrochemical Behavior of TiO2 Nanoparticle Doped WO3 Thin Films

    Directory of Open Access Journals (Sweden)

    Suvarna R. Bathe

    2014-01-01

    Full Text Available Nanoparticle TiO2 doped WO3 thin films by pulsed spray pyrolysis technique have been studied on fluorine tin doped (FTO and glass substrate. XRD shows amorphous nature for undoped and anatase phase of TiO2 having (101 plane for nanoparticle TiO2 doped WO3 thin film. SEM shows microfibrous reticulated porous network for WO3 with 600 nm fiber diameter and nanocrystalline having size 40 nm for TiO2 nanoparticle doped WO3 thin film. TiO2 nanoparticle doped WO3 thin film shows ~95% reversibility due to may be attributed to nanocrystalline nature of the film, which helpful for charge insertion and deinsertion process. The diffusion coefficient for TiO2 nanoparticle doped WO3 film is less than undoped WO3.

  6. WO3 nano-ribbons: their phase transformation from tungstite (WO3·H2O) to tungsten oxide (WO3)

    DEFF Research Database (Denmark)

    Ahmadi, Majid; Sahoo, Satyaprakash; Younesi, Reza

    2014-01-01

    Tungsten oxide (WO3) nano-ribbons (NRs) were obtained by annealing tungstite (WO3·H2O) NRs. The latter was synthesized below room temperature using a simple, environmentally benign, and low cost aging treatment of precursors made by adding hydrochloric acid to diluted sodium tungstate solutions (...

  7. Investigation of W/O microemulsion droplets by contrast variation ...

    Indian Academy of Sciences (India)

    various molar ratios (µ) of water to AOT and temperatures on water-in-oil (W/O) mi- croemulsions dispersed in n-heptane, ... tures composed of surfactant, water, and oil have attracted much interest since they form thermodynamically stable phases .... filter into dust-free sample cells. The cylindrical sample cells are made of ...

  8. Hydrothermal synthesis of CdWO nanorods and their ...

    African Journals Online (AJOL)

    NICO

    CdWO4 has a high refractive index, a high X-ray absorption coefficient, low radiation damage, high luminescence intensity and low afterglow to .... atomic number ratio of the elements of Cd, W and O is approxi- mately 1:1:4 and is consistent ...

  9. Morphologically different WO3 nanocrystals in photoelectrochemical water oxidation

    International Nuclear Information System (INIS)

    Biswas, Soumya Kanti; Baeg, Jin-Ook; Moon, Sang-Jin; Kong, Ki-jeong; So, Won-Wook

    2012-01-01

    Different morphologies of WO 3 nanocrystals such as nanorods and nanoplates have been obtained under hydrothermal conditions using ammonium metatungstate as the precursor in presence of different organic acids such as citric, oxalic, and tartaric acid in the reaction medium. Detailed characterization of the crystal structure, particle morphology, and optical band gap of the synthesized powders have been done by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and solid-state UV–visible spectroscopy study. The as-synthesized materials are WO 3 hydrates with orthorhombic phase which transform to the hexagonal WO 3 through dehydration upon heating at 350 °C. The resultant products are crystalline with nanoscale dimensions. Finally, the photoactivity of the synthesized materials annealed at 500 °C has been compared employing in photoelectrochemical water oxidation under the illumination of AM 1.5G simulated solar light (100 mWcm −2 ). The photocurrent measurements upon irradiation of light exhibit obvious photocatalytic activity with a photocurrent of about 0.77, 0.61, and 0.65 mAcm −2 for the WO 3 film derived with the oxalic acid, tartaric, and citric acid assisting agents, respectively, at 1.8 V versus Ag/AgCl electrode.

  10. Characterisation and application of WO3 films for electrochromic devices

    Science.gov (United States)

    Stapinski, Thomas; Marszalek, Konstanty; Swatowska, Barbara; Stanco, Agnieszka

    2013-07-01

    Electrochromic system is the one of the most popular devices using color memory effect under the influence of an applied voltage. The electrochromic system was produced based on the thin WO3 electrochromic films. Films were prepared by RF magnetron sputtering from tungsten targets in a reactive Ar+O2 gas atmosphere of various Ar/O2 ratios. The technological gas mixture pressure was 3 Pa and process temperature 30°C. Structural and optical properties of WO3 films were investigated for as-deposited and heat treated samples at temperature range from 350°C to 450°C in air. The material revealed the dependence of properties on preparation conditions and on post-deposition heat treatment. Main parameters of thin WO3 films: thickness d, refractive index n, extinction coefficient k and energy gap Eg were determined and optimized for application in electrochromic system. The main components of the system were glass plate with transparent conducting oxides, electrolyte, and glass plate with transparent conducting oxides and WO3 layer. The optical properties of the system were investigated when a voltage was applied across it. The electrochromic cell revealed the controllable transmittance depended on the operation voltage.

  11. Enhanced photocatalytic properties in well-ordered mesoporous WO3

    KAUST Repository

    Li, Li; Krissanasaeranee, Methira; Pattinson, Sebastian W.; Stefik, Morgan; Wiesner, Ulrich; Steiner, Ullrich; Eder, Dominik

    2010-01-01

    We used polyisoprene-block-ethyleneoxide copolymers as structure-directing agents to synthesise well-ordered and highly-crystalline mesoporous WO 3 architectures that possess improved photocatalytic properties due to enhanced dye-adsorption in absence of diffusion limitation. © 2010 The Royal Society of Chemistry.

  12. Characterization of nanoparticles of lidocaine in w/o microemulsions ...

    Indian Academy of Sciences (India)

    drophilic phase and a hydrophobic phase, stabilized with the use of surfactants. Regular MEs consist of nanometer-sized hydrocarbon domains (termed micelles) surrounded by amphiphilic molecules, stabilized in a continuous aqueous phase. In contrast, reverse (w/o) MEs consist of aqueous domains (termed reverse ...

  13. Photoelectrochemical Properties and Behavior of α-SnWO4 Photoanodes Synthesized by Hydrothermal Conversion of WO3 Films.

    Science.gov (United States)

    Zhu, Zhehao; Sarker, Pranab; Zhao, Chenqi; Zhou, Lite; Grimm, Ronald L; Huda, Muhammad N; Rao, Pratap M

    2017-01-18

    Metal oxides with moderate band gaps are desired for efficient production of hydrogen from sunlight and water via photoelectrochemical (PEC) water splitting. Here, we report an α-SnWO 4 photoanode synthesized by hydrothermal conversion of WO 3 films that achieves photon to current conversion at wavelengths up to 700 nm (1.78 eV). This photoanode is promising for overall PEC water-splitting because the flat-band potential and voltage of photocurrent onset are more negative than the potential of hydrogen evolution. Furthermore, the photoanode utilizes a large portion of the solar spectrum. However, the photocurrent density reaches only a small fraction of that which is theoretically possible. Density functional theory based thermodynamic and electronic structure calculations were performed to elucidate the nature and impact of defects in α-SnWO 4 prepared by this synthetic route, from which hole localization at Sn-at-W antisite defects was determined to be a likely cause for the poor photocurrent. Measurements further showed that the photocurrent decreases over time due to surface oxidation, which was suppressed by improving the kinetics of hole transfer at the semiconductor/electrolyte interface. Alternative synthetic methods and the addition of protective coatings and/or oxygen evolution catalysts are suggested to improve the PEC performance and stability of this promising α-SnWO 4 material.

  14. Preparation and characterization of nanocrystalline porous TiO2/WO3 composite thin films

    International Nuclear Information System (INIS)

    Hsu, C.-S.; Lin, C.-K.; Chan, C.-C.; Chang, C.-C.; Tsay, C.-Y.

    2006-01-01

    TiO 2 materials possessing not only photocatalytic but also electrochromic properties have attracted many research and development interests. Though WO 3 exhibits excellent electrochromic properties, the much higher cost and water-sensitivity of WO 3 as compared with the TiO 2 may restrict the practical application of WO 3 materials. In the present study, the feasibility of preparing nanocrystalline porous TiO 2 /WO 3 composite thin films was investigated. Precursors of sols TiO 2 and/or WO 3 and polystyrene microspheres were used to prepare nanocrystalline pure TiO 2 , WO 3 , and composite TiO 2 /WO 3 thin films by spin coating. The spin-coated thin films were amorphous and, after heat treating at a temperature of 500 o C, nanocrystalline TiO 2 , TiO 2 /WO 3 , and WO 3 thin films with or without pores were prepared successfully. The heat-treated thin films were colorless and coloration-bleaching phenomena can be observed during cyclic voltammetry tests. The heat-treated thin films exhibited good reversible electrochromic behavior while the porous TiO 2 /WO 3 composite film exhibited improved electrochromic properties

  15. Visible-light photocatalytic activity of Ag2O coated Bi2WO6 hierarchical microspheres assembled by nanosheets

    International Nuclear Information System (INIS)

    Chen, Lin; Hua, Hao; Yang, Qi; Hu, Chenguo

    2015-01-01

    Graphical abstract: - Highlights: • Bi 2 WO 6 hierarchical microspheres assembled by nanosheets and dispersed nanosheets are synthesized. • Ag 2 O/Bi 2 WO 6 heterostuctures exhibites an enhanced photocatalytic activity compared with the Bi 2 WO 6 nanostructures. • Photocatalytic activity of the Ag 2 O/Bi 2 WO 6 microspheres is higher than that of the nanosheets. • Bi 2 WO 6 hierarchical structure is an excellent architecture for loading of Ag 2 O nanoparticles. - Abstract: Bi 2 WO 6 hierarchical microspheres assembled by nanosheets and dispersed nanosheets were synthesized by hydrothermal reaction in different conditions. Ag 2 O nanoparticles were deposited on the surface of Bi 2 WO 6 microspheres and nanosheets by the chemical precipitation method. The photocatalytic performance of pure Bi 2 WO 6 nanostructures and Ag 2 O/Bi 2 WO 6 heterostructures were evaluated by the photocatalytic decolorization of RhB solution under visible-light irradiation. Compared with the pure Bi 2 WO 6 nanostructures, the Ag 2 O/Bi 2 WO 6 heterostructures exhibited an obviously enhanced photocatalytic activity. And photocatalytic activity of the Ag 2 O/Bi 2 WO 6 microspheres is higher than that of the Ag 2 O/Bi 2 WO 6 nanosheets. This work demonstrates that the Bi 2 WO 6 hierarchical three-dimensional structure is an excellent architecture for the loading of Ag 2 O nanoparticles to build a highly efficient photocatalyst

  16. Chemical purification of CaCO{sub 3} and CaWO{sub 4} powders used for CaWO{sub 4} crystal production for the CRESST experiment

    Energy Technology Data Exchange (ETDEWEB)

    Trinh Thi, H.H.; Defay, X.; Erb, A.; Hampf, R.; Lanfranchi, J.C.; Langenkaemper, A.; Morgalyuk, V.; Muenster, A.; Mondragon, E.; Oppenheimer, C.; Potzel, W.; Schoenert, S.; Steiger, H.; Ulrich, A.; Wawoczny, S.; Willers, M.; Zoeller, A. [Physik-Department and Excellence Cluster Universe, Technische Universitaet Muenchen, Garching (Germany)

    2016-07-01

    CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) uses CaWO{sub 4} single crystals as targets for the direct search for dark matter particles. Since several years these CaWO{sub 4} crystals are grown at the Technische Universitaet Muenchen. Thereby, commercially available CaCO{sub 3} and WO{sub 3} powders are used for the synthesis of CaWO{sub 4} powder. For the experiment low intrinsic contaminations of the crystals play a crucial role. In order to improve the radiopurity of the crystals it is necessary to reduce potential sources for radioactive backgrounds such as U and Th. In this poster we will present our studies of the chemical purification of the CaCO{sub 3} and CaWO{sub 4} powders.

  17. Fungus mediated biosynthesis of WO3 nanoparticles using Fusarium solani extract

    Science.gov (United States)

    Kavitha, N. S.; Venkatesh, K. S.; Palani, N. S.; Ilangovan, R.

    2017-05-01

    Currently nanoparticles were synthesized by emphasis bioremediation process due to less hazardous, eco-friendly and imperative applications on biogenic process. Fungus mediated biosynthesis strategy has been developed to prepare tungsten oxide nanoflakes (WO3, NFs) using the plant pathogenic fungus F.solani. The powder XRD pattern revealed the monoclinic crystal structure with improved crystalline nature of the synthesized WO3 nanoparticles. FESEM images showed the flake-like morphology of WO3, with average thickness and length around 40 nm and 300 nm respectively. The Raman spectrum of WO3 NFs showed their characteristic vibration modes that revealed the defect free nature of the WO3 NFs. Further, the elemental analysis indicated the stoichiometric composition of WO3 phase.

  18. Poly(methacrylic acid)-mediated morphosynthesis of PbWO4 micro-crystals

    International Nuclear Information System (INIS)

    Yu, J.G.; Zhao, X.F.; Liu, S.W.; Li, M.; Mann, S.; Ng, D.H.L.

    2007-01-01

    PbWO 4 crystals with various morphologies were fabricated via a facile poly(methacrylic acid)-mediated hydrothermal route. Novel microsized PbWO 4 single crystals with a needle-like shape as well as other morphologies, such as a fishbone, dendrite, sphere, spindle, ellipsoid, rod, and dumbbell with two dandelion-like heads, could be produced. The presence of PMAA, [Pb 2+ ]/[WO 4 2- ] molar ratio (R), and aging temperature played key roles in the formation of the PbWO 4 needle-like structures. Between temperatures of 60 to 150 C, the length and photoluminescence intensities of the PbWO 4 micro needles significantly increased with aging temperature, while the diameter did not change remarkably. Time-dependent experiments revealed that the formation of PbWO 4 microneedles involved an unusual growth process, involving nucleation, oriented assembly and controlled mesoscale restructuring of nanoparticle building blocks. (orig.)

  19. Preparation and characterization of WO{sub 3} nanoparticles, WO{sub 3}/TiO{sub 2} core/shell nanocomposites and PEDOT:PSS/WO{sub 3} composite thin films for photocatalytic and electrochromic applications

    Energy Technology Data Exchange (ETDEWEB)

    Boyadjiev, Stefan I., E-mail: boiajiev@gmail.com [MTA-BME Technical Analytical Chemistry Research Group, Szent Gellért tér 4, Budapest, H-1111 (Hungary); Santos, Gustavo dos Lopes; Szűcs, Júlia [Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry, Szent Gellért tér 4, Budapest, H-1111 (Hungary); Szilágyi, Imre M., E-mail: imre.szilagyi@mail.bme.hu [MTA-BME Technical Analytical Chemistry Research Group, Szent Gellért tér 4, Budapest, H-1111 (Hungary); Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry, Szent Gellért tér 4, Budapest, H-1111 (Hungary)

    2016-03-25

    In this study, monoclinic WO{sub 3} nanoparticles were obtained by thermal decomposition of (NH{sub 4}){sub x}WO{sub 3} in air at 600 °C. On them by atomic layer deposition (ALD) TiO{sub 2} films were deposited, and thus core/shell WO{sub 3}/TiO{sub 2} nanocomposites were prepared. We prepared composites of WO{sub 3} nanoparticles with conductive polymer as PEDOT:PSS, and deposited thin films of them on glass and ITO substrates by spin coating. The formation, morphology, composition and structure of the as-prepared pure and composite nanoparticles, as well thin films, were studied by TEM, SEM-EDX and XRD. The photocatalytic activity of both the WO{sub 3} and core/shell WO{sub 3}/TiO{sub 2} nanoparticles was studied by decomposing methyl orange in aqueous solution under UV light irradiation. Cyclic voltammetry measurements were performed on the composite PEDOT:PSS/WO{sub 3} thin films, and the coloring and bleaching states were studied.

  20. WO{sub 3} nanorods prepared by low-temperature seeded growth hydrothermal reaction

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Chai Yan [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Abdul Razak, Khairunisak, E-mail: khairunisak@eng.usm.my [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); NanoBiotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lockman, Zainovia, E-mail: zainovia@eng.usm.my [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2014-03-05

    Highlights: • WO{sub 3} nanorods with 5–10 nm diameter were grown directly on seeded tungsten foil. • WO{sub 3} nanorods were successfully grown at low temperature of 80 °C. • WO{sub 3} nanorods were grown on the entire surface of the seed layer after 24 h. • Annealed nanorods showed better electrochromic properties than as-made nanorods. -- Abstract: This work describes the first tungsten oxide (WO{sub 3}) nanorods hydrothermally grown on W foil. WO{sub 3} nanorods were successfully grown at low hydrothermal temperature of 80 °C by seeded growth hydrothermal reaction. The seed layer was prepared by thermally oxidized the W foil at 400 °C for 0.5 h. This work discusses the effect of hydrothermal reaction and annealing period on the morphological, structural, and electrochromic properties of WO{sub 3} nanorods. Various hydrothermal reaction periods (8–24 h) were studied. Monoclinic WO{sub 3} nanorods with 5–10 nm diameter were obtained after hydrothermal reaction for 24 h. These 24 h WO{sub 3} nanorods were also annealed at 400 °C with varying dwelling periods (0.5–4 h). Electrochromic properties of WO{sub 3} nanorods in an acidic electrolyte were analyzed using cyclic voltammetry and UV–vis spectrophotometry. WO{sub 3} nanorods annealed at 400 °C for 1 h showed the highest charge capacity and the largest optical contrast among the 24 h WO{sub 3} films. The sample also showed good cycling stability without significant degradation. Based on the results, the reaction mechanism of WO{sub 3} nanorod formation on W foil was proposed.

  1. Biomimetic fabrication of WO{sub 3} for water splitting under visible light with high performance

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Chao; Zhu, Shenmin, E-mail: smzhu@sjtu.edu.cn; Yao, Fan; Gu, Jiajun; Zhang, Wang [Shanghai Jiao Tong University, State Key Laboratory of Metal Matrix Composites (China); Chen, Zhixin [University of Wollongong, Faculty of Engineering (Australia); Zhang, Di, E-mail: zhangdi@sjtu.edu.cn [Shanghai Jiao Tong University, State Key Laboratory of Metal Matrix Composites (China)

    2013-08-15

    Inspired by the high light-harvesting properties of typical butterfly wings, ceramic WO{sub 3} butterfly wings with hierarchical structures of bio-butterfly wings was fabricated using a template of PapilioParis butterfly wings through a sol-gel method. The effect of calcination temperatures on the structures of the ceramic butterfly wings was investigated and the results showed that the WO{sub 3} butterfly wing replica calcined at 550 Degree-Sign C (WO{sub 3} replica-550) is a single phase and has a high crystallinity and relatively fine hierarchical structure. The average grain size of WO{sub 3} replica-550 and WO{sub 3} powder are around 32.6 and 42.2 nm, respectively. Compared with pure WO{sub 3} powder, WO{sub 3} replica-550 demonstrated a higher light-harvesting capability in the region from 460 to 700 nm and more importantly the higher charge separation rate, as evidenced by electron paramagnetic resonance measurements. Photocatalytic O{sub 2} evolutions from water were investigated on the ceramic butterfly wings and pure WO{sub 3} powder under visible light ({lambda} > 420 nm). The results showed that the amount of O{sub 2} produced from WO{sub 3} replica-550 is 50 % higher than that of the pure WO{sub 3} powder. The improved photocatalytic performance of WO{sub 3} replica-550 is attributed to the quasi-honeycomb structure inherited from the PapilioParis butterfly wings, providing both high light-harvesting efficiency and efficient charge transport through the WO{sub 3}.

  2. Effect of Structural Stress on the Laser Quality of Highly Doped Yb:KY(WO4)2/KY(WO4)2 and Yb:KLu(WO4)2/KLu(WO4)2 Epitaxial Structures

    International Nuclear Information System (INIS)

    Carvajal, J.; Raghothamachar, B.; Silvestre, O.; Chen, H.; Pujol, M.; Petrov, V.; Dudley, M.; Aguilo, M.; Diaz, F.

    2009-01-01

    In this communication we demonstrate how the difference in laser performance of two highly doped (20 at %) epitaxial layers of Yb-doped KY(WO4)2 (KYW) grown on a KYW substrate and Yb-doped KLu(WO4)2 (KLuW) grown on a KLuW substrate, respectively, is related to the presence of structural stress in the epilayers, investigated by synchrotron white beam X-ray topography. From the results obtained, it is clear that the samples that show a larger amount of structural stress, Yb:KYW/KYW epitaxies, lead to lower efficiency in laser operation, giving a direct correlation between the existence and magnitude of such structural stress and the loss in efficiency of laser performance in such epitaxial layers which, from a spectroscopical point of view, are otherwise equivalent.

  3. Electrochromism and local order in amorphous WO/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Zeller, H R; Beyeler, H U

    1977-06-01

    WO/sub 3/ films prepared under different conditions (evaporation, reactive sputtering and spraying of aqueous solutions of metatungstic acid) differ by orders of magnitude in their electrochromic sensitivity. Diffuse X-ray studies show the evaporated and sputtered films to be amorphous and to consists of a disordered network of corner sharing WO/sub 6/ octahedra. Sprayed films have different degrees of crystallinity depending on spraying conditions. From differential scanning calorimetry we conclude that the crystal water present in most films strongly affects the local order of the corner sharing octahedra. We find that crystal water not only provides a high ionic conductivity which is conditional for a fast electrochromic reaction but also stabilises electrocatalytically active surface sites for fast hydrogen or Li exchange with the adjacent electrolyte.

  4. Influence of Liquid Petroleum Gas on the Electrical Parameters of the WO3 Thick Film

    Directory of Open Access Journals (Sweden)

    R. S. KHADAYATE

    2007-02-01

    Full Text Available In this work, the WO3 thick films were prepared by standard screen-printing technology. These films were characterized by x-ray diffraction (XRD measurements and scanning electron microscopy (SEM. Influence of LPG on the electrical properties of the prepared WO3 thick film is reported. It was observed that the slope of the Arrhenius curves of the WO3 thick film decreased as the medium changed from pure air to 100 ppm LPG in air. From I-V characteristics, it was observed that the WO3 thick film exhibit highest sensitivity to 50 ppm LPG in air at 400oC.

  5. Study of the tungsten bronze Ag0.01WO3 using positron annihilation method

    International Nuclear Information System (INIS)

    Dryzek, J.; Dryzek, E.; Placzek, A.

    1992-01-01

    The study of the positron annihilation and the Seebeck effect was performed on silver doped tungsten trioxide of composition Ag 0.01 WO 3 and the tungsten trioxide phase: WO 2.90 (W 20 O 58 ). Both methods point out that there are some clusters of Ag + ions in the first compound and oxygen vacancies in the second case. The clusters have some internal substructure. The measurements of the Seebeck effect showed that Ag 0.01 WO 3 is normal n-type semiconductor whereas WO 2.90 exhibits metal-like properties

  6. Synthesis and characterization of polyaniline/MnWO4 nanocomposites as electrodes for pseudocapacitors

    Science.gov (United States)

    Saranya, S.; Selvan, R. Kalai; Priyadharsini, N.

    2012-03-01

    Polyaniline (PAni)/MnWO4 nanocomposite was successfully synthesized by in situ polymerization method under ultrasonication and the MnWO4 was prepared by surfactant assisted ultrasonication method. The thermal stability of PAni was determined by TG/DTA (Thermo Gravimetric/ Differential thermal analysis). The structural and morphological features of PAni, MnWO4 and PAni/MnWO4 composite was analyzed using Fourier transform infrared spectrometry, X-ray diffraction (XRD), scanning electron microscope (SEM) and Transmission electron microscope (TEM) images. The electro-chemical properties of PAni, MnWO4 and its composites with different weight percentage of MnWO4 loading were studied through cyclic voltammetry (CV) for the application of supercapacitors as active electrode materials. From the cyclic voltammogram, 50% of MnWO4 impregnated PAni showed a high specific capacitance (SC) of 481 F/g than their individual counterparts of PAni (396 F/g) and MnWO4 (18 F/g). The galvanostatic charge-discharge studies indicate the in situ polymerized composite shows greater specific capacitance (475 F/g) than the physical mixture (346 F/g) at a constant discharge current of 1 mA/cm2 with reasonable cycling stability. The charge transfer resistance (Rct) of PAni/MnWO4 composite (22 ohm) was calculated using electrochemical impedance spectroscopy (EIS) and compared with its physical mixture (58 ohm).

  7. Facile synthesis of hierarchical double-shell WO{sub 3} microspheres with enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhenfeng [College of Environment and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin 300387 (China); Chu, Deqing, E-mail: dqingchu@163.com [College of Environment and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin 300387 (China); Wang, Limin, E-mail: wanglimin@tjpu.edu.cn [School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin 300387 (China); Wang, Lipeng [School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Hu, Wenhui; Chen, Xiangyu; Yang, Huifang [College of Environment and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Sun, Jingjing [School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China)

    2017-02-28

    Highlights: • HDS-WO{sub 3} were fabricated via mild process. • A possible growth mechanism for HDS-WO{sub 3} is proposed. • The excellent photocatalytic activity is attributed to the larger surface area of the HDS-WO{sub 3} nanostructures. - Abstract: Hierarchical double-shell WO{sub 3} microspheres (HDS-WO{sub 3}) have been successfully obtained through the thermal decomposition of WO{sub 3}·H{sub 2}O formed by metal salts as the templates. The products were characterized by X-ray diffraction (XRD), and the morphology was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, the HDS-WO{sub 3} microspheres were analyzed by the Thermogravimetric (TG) and Brunauer-Emmett-Teller (BET) analysis. The synthetic mechanism of the products with hierarchical structures was proposed. The obtained HDS-WO{sub 3} exhibits excellent photocatalytic efficiency (84.9%), which is much higher than other WO{sub 3} sample under visible light illumination.

  8. MIS gas sensors based on porous silicon with Pd and WO{sub 3}/Pd electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Solntsev, V.S. [Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028, Kiev (Ukraine); Gorbanyuk, T.I., E-mail: tatyanagor@mail.r [Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028, Kiev (Ukraine); Litovchenko, V.G.; Evtukh, A.A. [Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028, Kiev (Ukraine)

    2009-09-30

    Pd and WO{sub 3}/Pd gate metal-oxide-semiconductor (MIS) gas sensitive structures based on porous silicon layers are studied by the high frequency C(V) method. The chemical compositions of composite WO{sub 3}/Pd electrodes are characterized by secondary-ion mass spectrometry (SIMS). The atomic force microscopy (AFM) was used for morphologic studies of WO{sub 3}/Pd films. As shown in the experiments, WO{sub 3}/Pd structures are more sensitive and selective to the adsorption of hydrogen sulphide compared to Pd gate. The analyses of kinetic characteristics allow us to determine the response and characteristic times for these structures. The response time of MIS-structures with thin composite WO{sub 3}/Pd electrodes (the thickness of Pd is about 50 nm with WO{sub 3} clusters on its surface) is slower compared to the structures with Pd electrodes. Slower sensor responses of WO{sub 3}-based gas sensors may be associated with different mechanism of gas sensitivity of given structures. The enhanced sensitivity and selectivity to H{sub 2}S action of WO{sub 3}/Pd MIS-structures can also be explained by the chemical reaction that occurs at the catalytic active surface of gate electrodes. The possible mechanisms of enhanced sensitivity and selectivity to H{sub 2}S adsorption of MIS gas sensors with WO{sub 3}/Pd composite gate electrodes compared to pure Pd have been analyzed.

  9. Tungsten oxides. I. Effects of oxygen vacancies and doping on electronic and optical properties of different phases of WO3

    Science.gov (United States)

    Migas, D. B.; Shaposhnikov, V. L.; Rodin, V. N.; Borisenko, V. E.

    2010-11-01

    In this part we present results of our ab initio calculations indicating that dispersion of the bands near the gap region for different phases of WO3 (namely, ɛ-WO3, δ-WO3, γ-WO3, β-WO3, orth-WO3, α-WO3, and hex-WO3) is rather close. The rapid increase in the absorption coefficient starts at the lower energy range for α-WO3 and hex-WO3 than for the other phases in accordance with the calculated band gaps. An oxygen vacancy has turned out to decrease the gap by 0.50 eV and to shift the absorption coefficient to the lower energy range in the room temperature γ-WO3 phase. We have also traced changes caused by molybdenum and sulfur doping of γ-WO3. Only sulfur doped γ-WO3 has been revealed to display the formation of the impurity band along with a sizable reduction in the gap and the shift in the absorption coefficient to the lower energy range.

  10. Progress in PbWO4 scintillating crystal

    International Nuclear Information System (INIS)

    Fyodorov, A.; Korzhik, M.; Missevitch, O.; Pavlenko, V.; Kachanov, V.; Singovsky, A.; Annenkov, A.N.; Ligun, V.A.; Peigneux, J.P.; Vialle, J.P.

    1994-12-01

    Lead tungstate PbWO 4 (PWO) has recently been shown to be a promising scintillating material for precise electromagnetic calorimetry. Modifications of PWO technology were made to improve the uniformity of the crystal properties. A model of the scintillation mechanism for PWO was developed and served to guide the improvement. The complex spectroscopic analysis of the crystal after improvement is presented, as well as the new crystal properties achieved. (K.A.). 14 refs., 14 figs., 4 tabs

  11. Photocatalytic properties of h-WO{sub 3} nanoparticles obtained by annealing and h-WO{sub 3} nanorods prepared by hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Boyadjiev, Stefan I., E-mail: boiajiev@gmail.com [MTA-BME Technical Analytical Chemistry Research Group, Szent Gellért tér 4, Budapest, H-1111 (Hungary); Nagy-Kovács, Teodóra [Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry, Szent Gellért tér 4, Budapest, H-1111 (Hungary); Lukács, István [Hungarian Academy of Sciences, Research Centre for Energy, Institute of Technical Physics and Materials Science, H-1121 Budapest, Konkoly Thege M. út 29-33 (Hungary); Szilágyi, Imre M., E-mail: imre.szilagyi@mail.bme.hu [MTA-BME Technical Analytical Chemistry Research Group, Szent Gellért tér 4, Budapest, H-1111 (Hungary); Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry, Szent Gellért tér 4, Budapest, H-1111 (Hungary)

    2016-03-25

    In the present study, two different methods for preparing hexagonal WO{sub 3} (h-WO{sub 3}) photocatalysts were used - controlled thermal decomposition and hydrothermal synthesis. WO{sub 3} nanoparticles with hexagonal structure were obtained by annealing (NH{sub 4}){sub x}WO{sub 3-y} at 500 °C in air. WO{sub 3} nanorods were prepared by a hydrothermal method using sodium tungstate Na{sub 2}WO{sub 4}, HCl, (COOH){sub 2} and NaSO{sub 4} precursors at 200 °C. The formation, morphology, structure and composition of the as-prepared nanoparticles and nanorods were studied by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDX). The photocatalytic activity of the h-WO{sub 3} nanoparticles and nanorods was studied by decomposing methyl orange in aqueous solution under UV light irradiation.

  12. Secondary recrystallisation in 20 w/o Cr-25 w/o Ni-Nb stabilised stainless steel

    International Nuclear Information System (INIS)

    Healey, T.; Brown, A.F.; Speight, M.V.

    1976-11-01

    The fuel cladding material for the Commercial Advanced Gas Reactor is a fine grain 20 w/o Cr-25 w/o Ni niobium stabilised stainless steel. The grain structure stability of this alloy has been investigated as a function of carbon content over the temperature range 930 - 990 0 C. It is demonstrated that the primary grain structure is susceptible to abnormal growth due to secondary recrystallisation of the initial fine grain structure after a composition and temperature dependent incubation period. The magnitude of the incubation period is analysed on the basis that secondary recrystallisation commences when randomly dispersed niobium carbide particles have coarsened to a critical size. The validity of the analysis is tested by comparing the predictions with experimental observation. The model is subsequently used to evaluate the incubation period for conditions of temperature, composition and microstructure which differ from those defined in the experimental studies. (author)

  13. CdWO4 polymorphs: Selective preparation, electronic structures, and photocatalytic activities

    International Nuclear Information System (INIS)

    Yan, Tingjiang; Li, Liping; Tong, Wenming; Zheng, Jing; Wang, Yunjian; Li, Guangshe

    2011-01-01

    This work explored the selective synthesis of polymorphs of CdWO 4 in either tetragonal or monoclinic phase by optimizing the experimental parameters. Systematic characterization indicated that both polymorphs possessed similar spherical morphologies but different structural building blocks. Electronic structures calculations for both polymorphs demonstrated the same constructions of conduction band or valence band, while the conduction band widths of both polymorphs were quite different. Both CdWO 4 polymorphs exhibited good photocatalytic activity for degradation of methyl orange under UV light irradiation. When comparing to some other well-known tungstate oxide materials, the photocatalytic activity was found to follow such a consequence, monoclinic CdWO 4 ∼monoclinic ZnWO 4 >tetragonal CdWO 4 >tetragonal CaWO 4 . The specific photocatalytic activity of monoclinic CdWO 4 was even higher than that of commercial TiO 2 photocatalyst (Degussa P25). The increased activity from the tetragonal CdWO 4 to the monoclinic was consistent with the trend of the decreased symmetry, and this could be explained in terms of the geometric structures and electronic structures for both polymorphs. -- Graphical abstract: Monoclinic CdWO 4 exhibited a much higher photocatalytic activity than the tetragonal form owing to the lower symmetry, more distorted geometric structure, and the dispersive band configuration. Display Omitted Research highlights: → Polymorphs of CdWO 4 in either tetragonal or monoclinic phase were selectively synthesized. → Both polymorphs possessed similar spherical morphologies, while the relevant structural building blocks were different. → Photocatalytic activities of CdWO 4 polymorphs depended strongly on the symmetry, geometric structure, as well as band configuration.

  14. Fiscal 1998 intellectual infrastructure project utilizing civil sector functions. Research and development project on prompt-effect type intellectual infrastructure creation (Research and development concerning environment-related reference materials); 1998 nendo minkan no kino wo katsuyoshita chiteki kiban jigyo seika hokokusho. Sokkogata chiteki kiban sosei kenkyu kaihatsu jigyo (kankyo kanren hyojun busshitsu ni kansuru kenkyu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Concerning an information providing system on environment-related reference materials, studies were conducted about the contents of information to be provided and about hardware and software suitable for such a system. In a survey of needs for such an information system, questionnaires were sent to 320 agencies and business corporations providing or utilizing reference materials in the field of chemistry and environments, and 158 answers were received. Further surveys were carried out by visiting more than 20 organizations providing or utilizing reference materials. As for activities overseas, surveys were conducted in Europe, North America, and Oceania, when IRMM (Institute for Reference Materials and Measurements) of Belgium, Merck KGaA of Germany, and some others were visited. It was then found that they desired that retrieval of information on reference materials in Japan and abroad be enabled by merely accessing related Internet sites. To meet the wish, a concept design was prepared of a comprehensive information system on reference materials in the form of an Internet home site. (NEDO)

  15. Fiscal 1998 intellectual infrastructure project utilizing civil sector functions. Research and development project on prompt-effect type intellectual infrastructure creation (Data buildup for assurance of safety of non-ferrous metals); 1998 nendo minkan no kino wo katsuyoshita chiteki kiban jigyo seika hokokusho. Sokkogata chiteki kiban sosei kenkyu kaihatsu jigyo (hitetsu kinzoku no anzensei kakuho ni shisuru data seibi)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Data were collected, put in an easy-to-use order, and developed into a database for safety assurance for automobiles and transportation equipment built of light metals as represented by aluminum. In the collection and arrangement of existing dynamics data, a database having 52 data relating to dynamic properties was prepared after retrieving data from academic essays previously published in Japan and abroad. In the testing of new materials, a Hopkinson high-speed rod-type impact/tensile tester was used to perform tensile tests at eight load application speeds between 0.5mm/min and 50m/sec for practical aluminum alloys 2024, 2091, 5052, 5083, 5254, 6061, 6063, 6NO1, 7075, and AC4CH. As the results, data on the 5000 and 6000 series alloys which had been insufficient were complemented. Data from a newly introduced multi-functional instrumentation Charpy impact tester were compared for study, correlations between property values obtained from bend test specimens and those obtained from tensile test specimens were evaluated, and then a simplified test evaluation method was proposed. (NEDO)

  16. Fiscal 1998 intellectual infrastructure project utilizing civil sector functions. Research and development project on prompt-effect type intellectual infrastructure creation (Comprehensive survey); 1998 nendo minkan no kino wo katsuyoshita chiteki kiban jigyo seika hokokusho. Sokkogata chiteki kiban sosei kenkyu kaihatsu jigyo (sogo chosa)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Surveys and studies were conducted to facilitate and invigorate research, development, and economic activities and to provide technology related intellectual assets in an organized, systematic way. In the survey related to the buildup of intellectual infrastructures, questionnaires were sent to 789 organizations in the industrial and academic domains concerning measuring standards, reference materials, base for information on biological resources, base for safety management of chemical substances, base relating to human life and welfare, and base of knowledge relating to materials. On-site surveys were also conducted in Asia, Australia, North America, and Europe. Concerning 10 inorganic reference solutions whose development is urged because they are related to environments, raw materials for them were selected, required purity levels were defined, and methods for measurement and evaluation of safety when in prolonged preservation were investigated. Conducted in the research and development of individual subjects were database buildup on thermophysical properties, research into long-term durability of heat-resistant composite materials, research into textural structure and characteristics as materials of sintered bodies of fine ceramics, database buildup on the safety of non-ferrous metals, studies of base of human characteristics measurement, and the like. (NEDO)

  17. Concerning problems of petroleum refining facilities. ; Promote international lateral work sharing, and strengthening of infrastructures in petroleum industry. Sekiyu seisei setsubi mondai ni tsuite. ; Kokusei suihei bungyo no suishin to sekiyu sangyo no kiban kyoka wo

    Energy Technology Data Exchange (ETDEWEB)

    1991-06-05

    This paper discusses how to promote international lateral work sharing and how to strengthen infrastructures in the petroleum industry, as a problem prevailing over the petroleum refining facilities in Japan. Excess distillation facilities have been applied with the disposition policy. However, in view of the supply and demand situation in petroleum products for medium to long term span in the world with the pan-Pacific region as the main concern, that applicable to Japan, and that experienced during the Persian Gulf crisis, the excess facility disposition policy was revised, particularly on white kerosene, of which supply and demand tightness is concerned about, so that production capacities may be increased as required. Japan, a large presence in the international economics, is required to work more positively on petroleum refining facilities located in the oil producing countries and intermediate locations to promote the international lateral work sharing. On the one hand, in order to strengthen the infrastructures in the Japanese petroleum industry, it is necessary to promote rationalization and use at higher efficiency of the oil supply system, and convergence of the the petroleum industry, including joint investments for projects exceeding capabilities of individual enterprises. 3 tabs.

  18. Visible-light photocatalytic activity of graphene oxide-wrapped Bi{sub 2}WO{sub 6} hierarchical microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Jiali; Yu, Hongwen, E-mail: yuhw@iga.ac.cn; Li, Haiyan; Sun, Lei; Zhang, Kexin; Yang, Hongjun

    2015-07-30

    Graphical abstract: - Highlights: • GO/Bi{sub 2}WO{sub 6} are readily fabricated by facile bubbling pretreatment and freeze drying. • GO/Bi{sub 2}WO{sub 6} possess excellent photocatalytic activity under visible light irradiation. • The visible light activity of GO/Bi{sub 2}WO{sub 6} is affected by the amount of GO. • The photostablity of GO is due to the photo-generated electrons transfer to Bi{sub 2}WO{sub 6}. - Abstract: A facile approach of fabricating homogeneous graphene oxide (GO)-wrapped Bi{sub 2}WO{sub 6} microspheres (GO/Bi{sub 2}WO{sub 6}) is developed. The transmission electron microscopy (TEM) results show that a heterojunction interface between GO and Bi{sub 2}WO{sub 6}. The UV–vis diffuse reflection spectra (DRS) reveal that the as-prepared GO/Bi{sub 2}WO{sub 6} composites own more intensive absorption in the visible light range compared with pure Bi{sub 2}WO{sub 6}. These characteristic structural and optical properties endow GO/Bi{sub 2}WO{sub 6} composites with enhanced photocatalytic activity. The enhanced photocatalytic activity of the GO/Bi{sub 2}WO{sub 6} is attributed predominantly to the synergetic effect between GO and Bi{sub 2}WO{sub 6}, causing rapid generation and separation of photo-generated charge carriers.

  19. Liquid phase deposition of WO3/TiO2 heterojunction films with high photoelectrocatalytic activity under visible light irradiation

    International Nuclear Information System (INIS)

    Zhang, Man; Yang, Changzhu; Pu, Wenhong; Tan, Yuanbin; Yang, Kun; Zhang, Jingdong

    2014-01-01

    Highlights: • Liquid phase deposition is developed for preparing WO 3 /TiO 2 heterojunction films. • TiO 2 film provides an excellent platform for WO 3 deposition. • WO 3 expands the absorption band edge of TiO 2 film to visible light region. • WO 3 /TiO 2 heterojunction film shows high photoelectrocatalytic activity. - ABSTRACT: The heterojunction films of WO 3 /TiO 2 were prepared by liquid phase deposition (LPD) method via two-step processes. The scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopic analysis indicated that flower-like WO 3 film was successfully deposited on TiO 2 film with the LPD processes. The TiO 2 film provided an excellent platform for WO 3 deposition while WO 3 obviously expanded the absorption of TiO 2 film to visible light. As the result, the heterojunction film of WO 3 /TiO 2 exhibited higher photocurrent response to visible light illumination than pure TiO 2 or WO 3 film. The photoelectrocatalytic (PEC) activity of WO 3 /TiO 2 film was evaluated by degrading Rhodamin B (RhB) and 4-chlorophenol (4-CP) under visible light irradiation. The results showed that the LPD WO 3 /TiO 2 film possessed high PEC activity for efficient removal of various refractory organic pollutants

  20. MnWO{sub 4} nanocapsules: Synthesis, characterization and its electrochemical sensing property

    Energy Technology Data Exchange (ETDEWEB)

    Muthamizh, Selvamani; Suresh, Ranganathan; Giribabu, Krishnamoorthy; Manigandan, Ramadoss; Praveen Kumar, Sivakumar; Munusamy, Settu; Narayanan, Vengidusamy, E-mail: vnnara@yahoo.co.in

    2015-01-15

    Highlights: • Synthesis of MnWO{sub 4} nanocapsules without use of any other external reagent. • High crystalline MnWO{sub 4} was obtained with phase purity. • Electrochemical sensing platform based on MnWO{sub 4} for sensing quercetin. • Micromolar detection ability of MnWO{sub 4} modified GCE. - Abstract: Manganese tungstate (MnWO{sub 4}) was synthesized by surfactant free precipitation method. MnWO{sub 4} was characterized by using various spectroscopic techniques. The phase, crystalline nature and the morphological analysis were carried out using XRD, scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HR-TEM). Further, FT-IR, Raman, and DRS-UV–Vis spectral analysis were carried out in order to ascertain the optical property and the presence of functional groups. From the analysis, the morphology of the MnWO{sub 4} was observed to be in capsules with breadth and thickness were in nm range. The oxidation state of tungsten (W), and manganese (Mn) were investigated using X-ray photo electron spectroscopy (XPS) and electron paramagnetic resonance spectroscopy (EPR). The synthesized MnWO{sub 4} nanocapsules were used to modify glassy carbon electrode (GCE) to detect quercetin.

  1. Influence of disordered morphology on electrochromic stability of WO{sub 3}/PPy

    Energy Technology Data Exchange (ETDEWEB)

    Gaikwad, Digambar K. [D. Y. Patil College of Engineering & Technology, Kasaba Bawada, Kolhapur, 416006, Maharashtra (India); Mali, Sawanta S.; Hong, Chang K. [Polymer Energy Materials Laboratory, Department of Advanced Chemical Engineering, Chonnam National University, Gwangju, 500-757 (Korea, Republic of); Kadam, Anamika V., E-mail: anamikasonavane@rediff.com [D. Y. Patil College of Engineering & Technology, Kasaba Bawada, Kolhapur, 416006, Maharashtra (India); D.Y. Patil Medical University, Kasaba Bawada, Kolhapur, 416006, Maharashtra (India)

    2016-06-05

    Tungsten oxide (WO{sub 3}) films are critical for smart windows because of their capacity of varying the throughput of visible light and solar energy. This study highlights the evolution of structural and morphological changes of electrodeposited WO{sub 3} thin films coated with polypyrrole (PPy) by using chemical bath deposition. The structural and surface properties of WO{sub 3} thin films were studied using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The electrochemical stability was inspected using repetitive cyclic voltammetry (CV) cycles for each sample in LiClO{sub 4}-PC electrolyte for prolonged periods. The results showed an improvement in the electrochemical stability after the CV study. - Graphical abstract: Mechanism: A schematic of the mechanism is proposed in above fig. The mechanism is based on three step process: (i) WO{sub 3} coated on ITO by electrodeposition followed by thermal treatment. It produces ordered nanoarrayed morphology. (ii) A second step involving deposition of PPy by chemical bath deposition on ITO. It possesses globular morphology. (iii) When PPy coated on WO{sub 3}, PPy applies shearing force on WO{sub 3} and produces disordered nanoarrayed morphology. - Highlights: • Nanoarrayed WO{sub 3}/PPy composite was synthesized. • Interplanar spacing enhances due to PPy coating. • PPy applies shearing force on WO{sub 3} produces disordered morphology. • Nanocomposite showed high stability in LiClO{sub 4}-PC.

  2. Photodegradation of Malachite Green by Nanostructured Bi2WO6 Visible Light-Induced Photocatalyst

    OpenAIRE

    Yijie Chen; Yaqin Zhang; Chen Liu; Aimin Lu; Weihua Zhang

    2012-01-01

    Bi2WO6 photocatalyst was first utilized to degrade malachite green. The effects of the concentration of malachite green, the pH value, and the concentration of Bi2WO6 on the photocatalytic efficiency were investigated. This study presents a strategy to eliminate highly toxic and persistent dyes such as malachite green.

  3. Oxidative degradation of salicylic acid by sprayed WO{sub 3} photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Mohite, S.V.; Rajpure, K.Y., E-mail: rajpure@yahoo.com

    2015-10-15

    Highlights: • The photoactivity of sprayed WO{sub 3} thin film. • Photoelectrocatalytic degradation of salicylic acid. • Reaction kinetics and mineralization of pollutants by COD. - Abstract: The WO{sub 3} thin films were deposited using spray pyrolysis technique. The prepared WO{sub 3} thin films were characterized using photoelectrochemical (PEC), X-ray diffraction, atomic force microscopy (AFM), and UV–vis absorbance spectroscopy techniques. PEC measurements of WO{sub 3} films deposited at different deposition temperatures were carried out to study photoresponse. The maximum photocurrent (I{sub ph} = 261 μA/cm{sup 2}) was observed for the film deposited at the 225 °C. The monoclinic crystal structure of WO{sub 3} has been confirmed from X-ray diffraction studies. AFM studies were used to calculate particle size and average roughness of the films. Optical absorbance was studied to estimate the bandgap energy of WO{sub 3} thin film which was about 2.65 eV. The photoelectrocatalytic activity of WO{sub 3} film was studied by degradation of salicylic acid with reducing concentrations as function of reaction time. The WO{sub 3} photocatalyst degraded salicylic acid to about 67.14% with significant reduction in chemical oxygen demand (COD) value.

  4. Optical properties of WO3 thin films using surface plasmon resonance technique

    International Nuclear Information System (INIS)

    Paliwal, Ayushi; Sharma, Anjali; Gupta, Vinay; Tomar, Monika

    2014-01-01

    Indigenously assembled surface plasmon resonance (SPR) technique has been exploited to study the thickness dependent dielectric properties of WO 3 thin films. WO 3 thin films (80 nm to 200 nm) have been deposited onto gold (Au) coated glass prism by sputtering technique. The structural, optical properties and surface morphology of the deposited WO 3 thin films were studied using X-ray diffraction, UV-visible spectrophotometer, Raman spectroscopy, and Scanning electron microscopy (SEM). XRD analysis shows that all the deposited WO 3 thin films are exhibiting preferred (020) orientation and Raman data indicates that the films possess single phase monoclinic structure. SEM images reveal the variation in grain size with increase in thickness. The SPR reflectance curves of the WO 3 /Au/prism structure were utilized to estimate the dielectric properties of WO 3 thin films at optical frequency (λ = 633 nm). As the thickness of WO 3 thin film increases from 80 nm to 200 nm, the dielectric constant is seen to be decreasing from 5.76 to 3.42, while the dielectric loss reduces from 0.098 to 0.01. The estimated value of refractive index of WO 3 film is in agreement to that obtained from UV-visible spectroscopy studies. The strong dispersion in refractive index is observed with wavelength of incident laser light

  5. Optical properties of WO{sub 3} thin films using surface plasmon resonance technique

    Energy Technology Data Exchange (ETDEWEB)

    Paliwal, Ayushi; Sharma, Anjali; Gupta, Vinay, E-mail: drguptavinay@gmail.com, E-mail: vgupta@physics.du.ac.in [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Tomar, Monika [Department of Physics, Miranda House, University of Delhi, Delhi 110007 (India)

    2014-01-28

    Indigenously assembled surface plasmon resonance (SPR) technique has been exploited to study the thickness dependent dielectric properties of WO{sub 3} thin films. WO{sub 3} thin films (80 nm to 200 nm) have been deposited onto gold (Au) coated glass prism by sputtering technique. The structural, optical properties and surface morphology of the deposited WO{sub 3} thin films were studied using X-ray diffraction, UV-visible spectrophotometer, Raman spectroscopy, and Scanning electron microscopy (SEM). XRD analysis shows that all the deposited WO{sub 3} thin films are exhibiting preferred (020) orientation and Raman data indicates that the films possess single phase monoclinic structure. SEM images reveal the variation in grain size with increase in thickness. The SPR reflectance curves of the WO{sub 3}/Au/prism structure were utilized to estimate the dielectric properties of WO{sub 3} thin films at optical frequency (λ = 633 nm). As the thickness of WO{sub 3} thin film increases from 80 nm to 200 nm, the dielectric constant is seen to be decreasing from 5.76 to 3.42, while the dielectric loss reduces from 0.098 to 0.01. The estimated value of refractive index of WO{sub 3} film is in agreement to that obtained from UV-visible spectroscopy studies. The strong dispersion in refractive index is observed with wavelength of incident laser light.

  6. A simple synthesis of MnWO{sub 4} nanoparticles as a novel energy storage material

    Energy Technology Data Exchange (ETDEWEB)

    Li, Feihui, E-mail: feihuili2012@163.com [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Xu, Xiaoyang, E-mail: xiaoyangxu2012@163.com [School of Science, Tianjin University (China); Huo, Jialei; Wang, Wei [School of Chemical Engineering, Tianjin 300072 (China)

    2015-11-01

    MnWO{sub 4} nanoparticles with the shuttle-like shape were prepared by a simple chemical co-precipitation method and analyzed by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The prepared MnWO{sub 4} was used as the electrode material of a supercapacitor, and its electrochemical performance was studied using cyclic voltammetry, galvanostatic charge/discharge cycles and electrochemical impedance spectroscopy. The MnWO{sub 4} exhibited good electrochemical performance. The MnWO{sub 4} nanoparticles had specific capacitances of 295 F/g at a scan rate of 5 mV/s and 219 F/g at a current density of 0.4 A/g. They also showed good cycle-life stability and low resistance. Therefore, MnWO{sub 4} is a promising electrode material for supercapacitors. - Highlights: • The shuttle-like MnWO{sub 4} nanoparticles have been prepared. • The prepared MnWO{sub 4} nanoparticles exhibit good electrochemical performances. • MnWO{sub 4} is a promising electrode material for supercapacitors.

  7. Optical spectroscopy of rare-earth ions doped KY(WO4)2 thin films

    NARCIS (Netherlands)

    García-Revilla, S.; Valiente, R.; Romanyuk, Y.E.; Utke, I.; Pollnau, Markus

    KY(WO4)2 thin films doped with Dy3+, Tb3+, Yb3+, were grown onto KY(WO4)2 substrates using liquid-phase epitaxy. Spectroscopic investigations of the grown layers were performed. Obtained results were compared with spectra given for bulk crystals. Upconversion experiments after direct Yb3+ excitation

  8. Physical properties characterization of WO3 films grown by hot-filament metal oxide deposition

    International Nuclear Information System (INIS)

    Diaz-Reyes, J.; Delgado-Macuil, R.J.; Dorantes-Garcia, V.; Perez-Benitez, A.; Balderas-Lopez, J.A.; Ariza-Ortega, J.A.

    2010-01-01

    WO 3 is grown by hot-filament metal oxide deposition (HFMOD) technique under atmospheric pressure and an oxygen atmosphere. By X-ray diffraction obtains that WO 3 presents mainly monoclinic crystalline phase. The chemical stoichiometry is obtained by X-ray Photoelectron Spectroscopy (XPS). The IR spectrum of the as-grown WO 3 presents broad peaks in the range of 1100 to 3600 cm -1 . A broad band in the 2200 to 3600 cm -1 region and the peaks sited at 1645 and 1432 cm -1 are well resolved, which are originated from moisture and are assigned to ν(OH) and δ(OH) modes of adsorbed water and the corresponding tungsten oxide vibrations are in infrared region from 400 to 1453 cm -1 and around 3492 cm -1 , which correspond to tungsten-oxygen (W-O) stretching, bending and lattice modes. The Raman spectrum shows intense peaks at 801, 710, 262 and 61 cm -1 that are typical Raman peaks of crystalline WO 3 (m-phase) that correspond to stretching vibrations of the bridging oxygen, which are assigned to W-O stretching (ν) and W-O bending (δ) modes, respectively. By transmittance measurements obtains that the WO 3 band gap can be varied from 2.92 to 3.13 eV in the investigated annealing temperature range.

  9. Improved electrochromical properties of sol-gel WO3 thin films by doping gold nanocrystals

    International Nuclear Information System (INIS)

    Naseri, N.; Azimirad, R.; Akhavan, O.; Moshfegh, A.Z.

    2010-01-01

    In this investigation, the effect of gold nanocrystals on the electrochromical properties of sol-gel Au doped WO 3 thin films has been studied. The Au-WO 3 thin films were dip-coated on both glass and indium tin oxide coated conducting glass substrates with various gold concentrations of 0, 3.2 and 6.4 mol%. Optical properties of the samples were studied by UV-visible spectrophotometry in a range of 300-1100 nm. The optical density spectra of the films showed the formation of gold nanoparticles in the films. The optical bandgap energy of Au-WO 3 films decreased with increasing the Au concentration. Crystalline structure of the doped films was investigated by X-ray diffractometry, which indicated formation of gold nanocrystals in amorphous WO 3 thin films. X-ray photoelectron spectroscopy (XPS) was used to study the surface chemical composition of the samples. XPS analysis indicated the presence of gold in metallic state and the formation of stoichiometric WO 3 . The electrochromic properties of the Au-WO 3 samples were also characterized using lithium-based electrolyte. It was found that doping of Au nanocrystals in WO 3 thin films improved the coloration time of the layer. In addition, it was shown that variation of Au concentration led to color change in the colored state of the Au-WO 3 thin films.

  10. Characterization of MAPLE deposited WO3 thin films for electrochromic applications

    Science.gov (United States)

    Boyadjiev, S. I.; Stefan, N.; Szilágyi, I. M.; Mihailescu, N.; Visan, A.; Mihailescu, I. N.; Stan, G. E.; Besleaga, C.; Iliev, M. T.; Gesheva, K. A.

    2017-01-01

    Tungsten trioxide (WO3) is a widely studied material for electrochromic applications. The structure, morphology and optical properties of WO3 thin films, grown by matrix assisted pulsed laser evaporation (MAPLE) from monoclinic WO3 nano-sized particles, were investigated for their possible application as electrochromic layers. A KrF* excimer (λ=248 nm, ζFWHM=25 ns) laser source was used in all experiments. The MAPLE deposited WO3 thin films were studied by atomic force microscopy (AFM), grazing incidence X-ray diffraction (GIXRD) and Fourier transform infrared spectroscopy (FTIR). Cyclic voltammetry measurements were also performed, and the coloring and bleaching were observed. The morpho-structural investigations disclosed the synthesis of single-phase monoclinic WO3 films consisting of crystalline nano-grains embedded in an amorphous matrix. All thin films showed good electrochromic properties, thus validating application of the MAPLE deposition technique for the further development of electrochromic devices.

  11. Characterization of MAPLE deposited WO3 thin films for electrochromic applications

    International Nuclear Information System (INIS)

    Boyadjiev, S I; Iliev, M T; Stefan, N; Mihailescu, N; Visan, A; Mihailescu, I N; Szilágyi, I M; Stan, G E; Besleaga, C; Gesheva, K A

    2017-01-01

    Tungsten trioxide (WO 3 ) is a widely studied material for electrochromic applications. The structure, morphology and optical properties of WO 3 thin films, grown by matrix assisted pulsed laser evaporation (MAPLE) from monoclinic WO 3 nano-sized particles, were investigated for their possible application as electrochromic layers. A KrF* excimer (λ=248 nm, ζ FWHM =25 ns) laser source was used in all experiments. The MAPLE deposited WO 3 thin films were studied by atomic force microscopy (AFM), grazing incidence X-ray diffraction (GIXRD) and Fourier transform infrared spectroscopy (FTIR). Cyclic voltammetry measurements were also performed, and the coloring and bleaching were observed. The morpho-structural investigations disclosed the synthesis of single-phase monoclinic WO 3 films consisting of crystalline nano-grains embedded in an amorphous matrix. All thin films showed good electrochromic properties, thus validating application of the MAPLE deposition technique for the further development of electrochromic devices. (paper)

  12. Enhanced photoelectrochemical and photocatalytic activity of WO3-surface modified TiO2 thin film

    Science.gov (United States)

    Qamar, Mohammad; Drmosh, Qasem; Ahmed, Muhammad I.; Qamaruddin, Muhammad; Yamani, Zain H.

    2015-02-01

    Development of nanostructured photocatalysts for harnessing solar energy in energy-efficient and environmentally benign way remains an important area of research. Pure and WO3-surface modified thin films of TiO2 were prepared by magnetron sputtering on indium tin oxide glass, and photoelectrochemical and photocatalytic activities of these films were studied. TiO2 particles were <50 nm, while deposited WO3 particles were <20 nm in size. An enhancement in the photocurrent was observed when the TiO2 surface was modified WO3 nanoparticles. Effect of potential, WO3 amount, and radiations of different wavelengths on the photoelectrochemical activity of TiO2 electrodes was investigated. Photocatalytic activity of TiO2 and WO3-modified TiO2 for the decolorization of methyl orange was tested.

  13. CW lasing of Ho in KLu(WO4)2 in-band pumped by a diode-pumped Tm:KLu(WO4)2 laser.

    Science.gov (United States)

    Mateos, Xavier; Jambunathan, Venkatesan; Pujol, Maria Cinta; Carvajal, Joan Josep; Díaz, Francesc; Aguiló, Magdalena; Griebner, Uwe; Petrov, Valentin

    2010-09-27

    We demonstrate continuous wave (CW) room temperature laser operation of the monoclinic Ho(3+)-doped KLu(WO(4))(2) crystal using a diode-pumped Tm(3+):KLu(WO(4))(2) laser for in-band pumping. The slope efficiency achieved amounts to ~55% with respect to the absorbed power and the maximum output power of 648 mW is generated at 2078 nm.

  14. Enhancement of visible-light photocatalytic activity of silver and mesoporous carbon co-modified Bi2WO6

    International Nuclear Information System (INIS)

    Zhao, Qian; Gong, Ming; Liu, Wangping; Mao, Yulin; Le, Shukun; Ju, Shang; Long, Fei; Liu, Xiufang; Liu, Kai; Jiang, Tingshun

    2015-01-01

    Graphical abstract: - Highlights: • Silver and mesoporous carbon co-modified Bi 2 WO 6 (Ag/Bi 2 WO 6 /CMK-3) composite was prepared. • Photocatalytic activity of Bi 2 WO 6 was remarkably enhanced by co-modification of silver and mesoporous carbon. • The degradation rate of MB can reach ca. 95.1% under visible light irradiation. • The Ag/Bi 2 WO 6 /CMK-3 composite has good stability and potential application prospects. - Abstract: Ordered mesoporous carbon CMK-3 was prepared by hard template method using SBA-15 as template, sucrose as carbon source. Flower/sphere-like Bi 2 WO 6 and CMK-3/Bi 2 WO 6 photocatalysts were synthesized by hydrothermal method, and then Ag/Bi 2 WO 6 and Ag/Bi 2 WO 6 /CMK-3 composite photocatalysts were prepared via a photoreduction process. The samples were characterized by XRD, UV–vis, TEM (HR-TEM), SEM, N 2 physical adsorption and PL and their photocatalytic activities were evaluated by the photocatalytic degradation of methylene blue (MB) under visible light irradiation. The results show that both incorporating of CMK-3 and Ag loading greatly improved the photocatalytic activity of Bi 2 WO 6 , and the content of CMK-3 and silver have an impact on the photocatalytic activity of Bi 2 WO 6 . The photocatalytic activity of Ag/Bi 2 WO 6 /CMK-3 photocatalyst is superior to the activities of CMK-3/Bi 2 WO 6 and Ag/Bi 2 WO 6 under comparable conditions, and Ag/Bi 2 WO 6 /CMK-3 photocatalyst has high stability and is easy to be recycled. Also, the mechanism for the enhancement of the photocatalytic activity of CMK-3 and Ag co-modified Bi 2 WO 6 was also investigated

  15. The enhanced alcohol-sensing response of ultrathin WO3 nanoplates

    International Nuclear Information System (INIS)

    Chen Deliang; Hou Xianxiang; Wen Hejing; Wang Yu; Wang Hailong; Zhang Rui; Lu Hongxia; Xu Hongliang; Guan Shaokang; Li Xinjian; Sun Jing; Gao Lian

    2010-01-01

    Chemical sensors based on semiconducting metal oxide nanocrystals are of academic and practical significance in industrial processing and environment-related applications. Novel alcohol response sensors using two-dimensional WO 3 nanoplates as active elements have been investigated in this paper. Single-crystalline WO 3 nanoplates were synthesized through a topochemical approach on the basis of intercalation chemistry (Chen et al 2008 Small 4 1813). The as-obtained WO 3 nanoplate pastes were coated on the surface of an Al 2 O 3 ceramic microtube with four Pt electrodes to measure their alcohol-sensing properties. The results show that the WO 3 nanoplate sensors are highly sensitive to alcohols (e.g., methanol, ethanol, isopropanol and butanol) at moderate operating temperatures (260-360 deg. C). For butanol, the WO 3 nanoplate sensors have a sensitivity of 31 at 2 ppm and 161 at 100 ppm, operating at 300 deg. C. For other alcohols, WO 3 nanoplate sensors also show high sensitivities: 33 for methanol at 300 ppm, 70 for ethanol at 200 ppm, and 75 for isopropanol at 200 ppm. The response and recovery times of the WO 3 nanoplate sensors are less than 15 s for all the test alcohols. A good linear relationship between the sensitivity and alcohol concentrations has been observed in the range of 2-300 ppm, whereas the WO 3 nanoparticle sensors have not shown such a linear relationship. The sensitivities of the WO 3 nanoplate sensors decrease and their response times become short when the operating temperatures increase. The enhanced alcohol-sensing performance could be attributed to the ultrathin platelike morphology, the high crystallinity and the loosely assembling structure of the WO 3 nanoplates, due to the advantages of the effective adsorption and rapid diffusion of the alcohol molecules.

  16. Porous three-dimensional reduced graphene oxide merged with WO3 for efficient removal of radioactive strontium

    Science.gov (United States)

    Mu, Wanjun; Yu, Qianghong; Hu, rui; Li, Xingliang; Wei, Hongyuan; Jian, Yuan

    2017-11-01

    A simple hydrothermal method was used to prepare 3D nanostructured composite adsorbents of reduced graphene oxide (RGO) and WO3 (RGO/WO3). The analysis results suggest that it possesses a mesoporous 3D structure, in which WO3 nanorods are uniformly loaded on the surface of the RGO. Combining the benefits of GO and WO3, the composites exhibit a higher adsorption capacity for removing Sr2+ from aqueous solutions over a wide pH range (4-11). Adsorption isotherms show that the data fit the Langmuir isotherms well (R > 0.99), and the maximum adsorption capacity of 149.56 mg g-1 was achieved, much higher than that for GO, WO3 and other similar adsorbents. Sr2+ adsorption on RGO/WO3 reached equilibrium within 200 min. The fast adsorption and high adsorption rate of RGO/WO3 are mostly attributable to the plentiful adsorption sites provided by the dispersed WO3 nanoparticles on the RGO surface. Furthermore, the existence of Na+ ions has no obvious effect on the removal of Sr2+ ions by RGO/WO3, and RGO/WO3 adsorbent can be repeated at least 5 times without significant loss of adsorption capacity by adsorption-desorption experiment. Thus, RGO/WO3 shows the potential ability for removal of 90Sr from radioactive wastewater.

  17. Subsolidus Phase Relations of the CaO-WO3-CuO System at 800 °C in Air

    DEFF Research Database (Denmark)

    Grivel, J. -C.

    2012-01-01

    The subsolidus phase relations of the CaO-WO3-CuO system were investigated in air. The samples were equilibrated at 800 degrees C. Under these conditions, five binary oxide phases are stable: Ca2CuO3, Cu3WO6, CuWO4, CaWO4 and Ca3WO6. The pseudo-ternary section is characterised by 6 three...

  18. Ag loaded WO_3 nanoplates for efficient photocatalytic degradation of sulfanilamide and their bactericidal effect under visible light irradiation

    International Nuclear Information System (INIS)

    Zhu, Wenyu; Liu, Jincheng; Yu, Shuyan; Zhou, Yan; Yan, Xiaoli

    2016-01-01

    Highlights: • WO_3/Ag heterogeneous composites were fabricated with simply photo-reduction method. • Property changes due to Ag loading were systematically studied. • WO_3/Ag composites efficiently degraded sulfanilamide under visible light irradiation. • WO_3/Ag composites exhibited bactericidal effectS under visible light irradiation. - Abstract: Sulfonamides (SAs) are extensively used antibiotics and their residues in the water bodies propose potential threat to the public. In this study, degradation efficiency of sulfanilamide (SAM), which is the precursor of SAs, using WO_3 nanoplates and their Ag heterogeneous as photocatalysts was investigated. WO_3 nanoplates with uniform size were synthesized by a facile one step hydrothermal method. Different amount of Ag nanoparticles (Ag NPs) were loaded onto WO_3 nanoplates using a photo-reduction method to generate WO_3/Ag composites. The physio-chemical properties of synthesized nanomaterials were systematically characterized. Photodegradation of SAM by WO_3 and WO_3/Ag composites was conducted under visible light irradiation. The results show that WO_3/Ag composites performed much better than pure WO_3 where the highest removal rate was 96.2% in 5 h. Ag as excellent antibacterial agent also endows certain antibacterial efficiency to WO_3, and 100% removal efficiency against Escherichia Coli and Bacillus subtilis could be achieved in 2 h under visible light irradiation for all three WO_3/Ag composites synthesized. The improved performance in terms of SAM degradation and antibacterial activity of WO_3/Ag can be attributed to the improved electron-hole pair separation rate where Ag NPs act as effective electron trapper during the photocatalytic process.

  19. Negative thermal expansion in Sc2(WO4)3

    International Nuclear Information System (INIS)

    Evans, J.S.O.; Mary, T.A.; Sleight, A.W.

    1998-01-01

    Sc 2 (WO 4 ) 3 has been found to show the highly unusual property of negative thermal expansion over a temperature range of 10 to 1,073 K. Powder neutron diffraction data from 10 to 450 K shows an essentially linear decrease in cell volume as a function of temperature. The intrinsic linear coefficient of thermal expansion from this data is -2.2 x 10 -6 K -1 . The linear coefficient of thermal expansion measured on a ceramic bar of Sc 2 (WO 4 ) 3 can be as negative as -11 x 10 -6 K -1 due to microstructure changes as a function of temperature. Rietveld refinement as a function of temperature suggests that the intrinsic negative thermal expansion can be related to transverse vibrations of bridging oxygen atoms in the structure. The anharmonic nature of these vibrations leads to a coupled tilting of the quasi-rigid framework polyhedra. This tilting in turn causes the structure to become more dense with increasing temperature

  20. Investigation of the optical property and structure of WO3 thin films with different sputtering depositions

    Science.gov (United States)

    Chen, Hsi-Chao; Jan, Der-Jun; Chen, Chien-Han; Huang, Kuo-Ting; Lo, Yen-Ming; Chen, Sheng-Hui

    2011-09-01

    The purpose of this research was to compare the optical properties and structure of tungsten oxide (WO3) thin films that was deposited by different sputtering depositions. WO3 thin films deposited by two different depositions of direct current (DC) magnetron sputtering and pulsed DC sputtering. A 99.95% WO3 target was used as the starting material for these depositions. These WO3 thin films were deposited on the ITO glass, PET and silicon substrate by different ratios of oxygen and argon. A shadow moiré interferometer would be introduced to measure the residual stress for PET substrate. RF magnetron sputtering had the large residual stress than the other's depositions. A Raman spectrum could exhibit the phase of oxidation of WO3 thin film by different depositions. At the ratio of oxygen and argon was about 1:1, and the WO3 thin films had the best oxidation. However, it was important at the change of the transmittance (ΔT = Tbleached - Tcolored) between the coloring and bleaching for the smart window. Therefore, we also found the WO3 thin films had the large variation of transmittance between the coloring and bleaching at the gas ratios of oxygen and argon of 1:1.

  1. Low-temperature molten salt synthesis and characterization of CoWO4 nano-particles

    International Nuclear Information System (INIS)

    Song Zuwei; Ma Junfeng; Sun Huyuan; Sun Yong; Fang Jingrui; Liu Zhengsen; Gao Chang; Liu Ye; Zhao Jingang

    2009-01-01

    CoWO 4 nano-particles were successfully synthesized at a low temperature of 270 deg. C by a molten salt method, and effects of such processing parameters as holding time and salt quantity on the crystallization and development of CoWO 4 crystallites were initially studied. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescent spectra techniques (PL), respectively. Experimental results showed that the well-crystallized CoWO 4 nano-particles with ca. 45 nm in diameter could be obtained at 270 deg. C for a holding time of 8 h with 6:1 mass ratio of the salt to CoWO 4 precursor, and XRD analysis evidenced that the as-prepared sample was a pure monoclinic phase of CoWO 4 with wolframite structure. Their PL spectra revealed that the CoWO 4 nano-particles displayed a very strong PL peak at 453 nm with the excitation wavelength of 230 nm, and PL properties of CoWO 4 crystallites relied on their crystalline state, especially on their particle size.

  2. Gas sensing properties of graphene–WO3 composites prepared by hydrothermal method

    International Nuclear Information System (INIS)

    Chu, Xiangfeng; Hu, Tao; Gao, Feng; Dong, Yongping; Sun, Wenqi; Bai, Linshan

    2015-01-01

    Graphical abstract: - Highlights: • The amount of graphene had an effect on the morphology of graphene–WO 3 composites. • The optimum temperature of 0.1 wt% graphene–WO 3 sensor to acetaldehyde was 100 °C. • 0.1 wt% graphene–WO 3 sensor exhibited good selectivity to acetaldehyde at 100 °C. - Abstract: Graphene–WO 3 composites mixed with different amounts of graphene (0, 0.1, 0.5, 1 and 3 wt%) were prepared by hydrothermal method at 180 °C for 24 h. The as-prepared graphite oxide, graphene and graphene–WO 3 composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR) and Raman spectroscopy, respectively. The effect of the amount of graphene in the composites on the gas-sensing responses and the gas-sensing selectivity of the materials was investigated. The experimental results revealed that the sensor based on 0.1 wt% graphene–WO 3 composite exhibited high response and good selectivity to acetaldehyde vapor at 100 °C, the optimum operating temperature of this sensor to 1000 ppm acetaldehyde vapor decreased from 180 °C to 100 °C comparing with that of pure WO 3 . The response time and the recovery time for 100 ppm acetaldehyde vapor were 250 s and 225 s, respectively

  3. Tungsten oxide (WO3) thin films for application in advanced energy systems

    International Nuclear Information System (INIS)

    Gullapalli, S. K.; Vemuri, R. S.; Manciu, F. S.; Enriquez, J. L.; Ramana, C. V.

    2010-01-01

    Inherent processes in coal gasification plants produce hazardous hydrogen sulfide (H 2 S), which must be continuously and efficiently detected and removed before the fuel is used for power generation. An attempt has been made in this work to fabricate tungsten oxide (WO 3 ) thin films by radio-frequency reactive magnetron-sputter deposition. The impetus being the use of WO 3 films for H 2 S sensors in coal gasification plants. The effect of growth temperature, which is varied in the range of 30-500 deg. C, on the growth and microstructure of WO 3 thin films is investigated. Characterizations made using scanning electron microscopy (SEM) and x-ray diffraction (XRD) indicate that the effect of temperature is significant on the microstructure of WO 3 films. XRD and SEM results indicate that the WO 3 films grown at room temperature are amorphous, whereas films grown at higher temperatures are nanocrystalline. The average grain-size increases with increasing temperature. WO 3 films exhibit smooth morphology at growth temperatures ≤300 deg. C while relatively rough at >300 deg. C. The analyses indicate that the nanocrystalline WO 3 films grown at 100-300 deg. C could be the potential candidates for H 2 S sensor development for application in coal gasification systems.

  4. Enhanced electrochromic coloration in Ag nanoparticle decorated WO3 thin films

    International Nuclear Information System (INIS)

    Kharade, Rohini R.; Mali, Sawanta S.; Patil, Satish P.; Patil, Kashinath R.; Gang, Myong G.; Patil, Pramod S.; Kim, Jin H.; Bhosale, Popatrao N.

    2013-01-01

    Highlights: • Electrochromic WO 3 /Ag nanocomposites prepared by hybrid physico-chemical route. • XRD and XPS results confirm formation of Ag 8 W 4 O 16 phase. • WO 3 /Ag thin films showed good optical transmittance change and coloration efficiency. • SPR enhanced coloration and bleaching mechanism is well explained for electrochromism. • Color stimuli are quantified using CIE chromaticity principles. -- Abstract: WO 3 /Ag composite thin films were prepared by microwave assisted sol–gel synthesis (MW-SGS) of WO 3 followed by vacuum evaporation of Ag nanoparticles and their enhanced electrochromic coloration was investigated. The composition and morphology of WO 3 thin films with different thickness of Ag layer obtained by vacuum evaporation were investigated. Distinct plasmon absorption bands of Ag nanoparticle thin films were obtained. The optical band gap energy of WO 3 /Ag films decreased with increasing the Ag layer thickness. The surface of these films has been examined using X-ray photoelectron spectroscopy (XPS) to gain information about the chemical states of species present at surfaces. Experimental results indicated that the conductivity of the films increased after surface modification by Ag layer. To investigate the origin of enhanced electrochromic absorption in optical properties, working electrode consisting of WO 3 /Ag thin film was used and observed the optical properties during electrochemical reaction. It was found that composite electrode shows enhancement in electrochromic properties in terms of optical modulation (ΔOD) and coloration efficiency (η)

  5. Template-free hydrothermal synthesis and high photocatalytic activity of ZnWO4 nanorods

    International Nuclear Information System (INIS)

    Gao, Bin; Fan, Huiqing; Zhang, Xiaojun; Song, Lixun

    2012-01-01

    Highlights: ► ZnWO 4 nanorods with uniform diameter are successfully prepared through a template-free hydrothermal method. ► The crystallinity of the products is influenced by the pH value of initial precursor suspension. ► Photocatalytic activity of the ZnWO 4 nanorods for degradation of methylene blue is evaluated. ► The ZnWO 4 nanorods exhibit good stability of photocatalytic activity. - Abstract: ZnWO 4 nanorods are successfully synthesized by a template-free hydrothermal method, and are characterized in detail by X-ray diffractometer (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED). The results show that the ZnWO 4 nanorods with wolframite structure are well-crystallized single crystallites. The crystallinity of the products is influenced by the pH value of initial precursor suspension. The width and length of the synthesized samples increase with hydrothermal reaction temperature. The photocatalytic efficiency of the ZnWO 4 nanorods for degradation of methylene blue (MB) in aqueous solution under UV light irradiation declines greatly with increasing crystallinity. The ZnWO 4 nanorods prepared at pH of 4 have the best activity in photo-degradation of MB. After six recycles, photocatalytic activity loss of the catalyst is not obvious.

  6. Controlled synthesis of three-dimensional hierarchical Bi2WO6 microspheres with optimum photocatalytic activity

    International Nuclear Information System (INIS)

    Wang, Hong; Song, Jimei; Zhang, Hui; Gao, Fei; Zhao, Shaojuan; Hu, Haiqin

    2012-01-01

    Highlights: ► The synthesized method is very simple. It can be widely used in the production. ► The morphology is novel and the property is fine. ► The formation of 3D hierarchical microsphere can be induced by changing the concentration of KNO 3 . -- Abstract: Three-dimensional (3D) hierarchical Bi 2 WO 6 microsphere and octahedral Bi 2 WO 6 have been synthesized by a facile hydrothermal method using KNO 3 solution and distilled water as solvent, respectively. The obtained products were characterized by X-ray diffraction, scanning electron microscopy, N 2 adsorption/desorption, and UV–vis diffuse reflectance spectroscopy in detail. The concentration of KNO 3 played a key role in the formation of 3D hierarchical Bi 2 WO 6 microspheres. A possible formation mechanism of Bi 2 WO 6 microsphere was proposed. The photocatalytic activity of the as-synthesized products was evaluated by monitoring the degradation of MB solution under sunlight irradiation. It was found that the photocatalytic activity of the 3D hierarchical Bi 2 WO 6 microsphere was superior to the octahedral Bi 2 WO 6 , which was attributed to the larger surface area and special hierarchical structure of Bi 2 WO 6 microsphere.

  7. Synthesis of WO3 flower-like hierarchical architectures and their sensing properties

    International Nuclear Information System (INIS)

    Meng, Dan; Wang, Guosheng; San, Xiaoguang; Song, Yinmin; Shen, Yanbai; Zhang, Yajing; Wang, Kangjun; Meng, Fanli

    2015-01-01

    WO 3 flower-like hierarchical architectures were synthesized by hydrothermal process using sodium tungstate (Na 2 WO 4 ·2H 2 O) as tungsten source and citric acid (CA) as an assistant agent. The morphology and crystal structure were investigated using scanning electron microscope and X-ray diffractometer. It is found that CA played a significant role in governing morphologies of product during hydrothermal process. The obtained products were identified as triclinic crystal WO 3 structure. The ethanol gas sensing measurements showed that well-defined WO 3 flower-like structures synthesized at CA/W molar ratio of 1 with large specific surface area exhibited the higher responses compared with others at all operating temperatures. Moreover, the reversible and fast response to ethanol gas at various gas concentrations and good selectivity were obtained. The results indicated that the WO 3 flower-like hierarchical architectures are promising materials for gas sensors. - Highlights: • WO 3 flower-like structures were successfully synthesized by hydrothermal method. • The effect of citric acid amount on morphologies was investigated. • Good ethanol gas sensing properties of WO 3 flower-like structures were obtained

  8. Synthesis, characterization and photocatalytic activity of porous WO3/TiO2 hollow microspheres

    International Nuclear Information System (INIS)

    Yang, Liuyang; Si, Zhichun; Weng, Duan; Yao, Youwei

    2014-01-01

    Porous WO 3 /TiO 2 hollow microspheres were prepared by a spray drying method for photodegradation of methylene blue and phenol. The catalysts were characterized by X-ray diffraction, Field Emission Scanning Electron Microscope, High Resolution Transmission Electron Microscope, N 2 adsorption–desorption measurements, Raman spectrometer, UV–Vis Diffuse Reflectance Spectroscopy and Zeta-Meter measurements. The results showed that the tungsten oxides mainly existed in highly dispersed amorphous form on anatase when the loading amount of tungsten oxide was below 3 mol%. The improved photocatalytic activity under UV light irradiation of the WO 3 /TiO 2 catalyst mainly arises from the enhanced charge separation efficiency rather than the improved light absorbance by highly dispersed amorphous tungsten oxides. Highly dispersed amorphous WO x can form a shallowly trapped site due to its similar band structure with TiO 2 . The strongly electron-withdrawing of tungsten oxide in highly dispersed state facilitates the electron transition between titanium and WO x , and consequently improves the charge separation. The enhanced acidity of catalyst by WO x in reactant environment also improved the charge separation efficiency due to the timely transition of holes and electrons accumulated on TiO 2 and WO x , respectively. However, the improved photocatalytic activity under visible light irradiation of the WO 3 /TiO 2 catalyst mainly arises from light harvest. TiO 2 containing 3 mol% WO 3 displayed the highest photocatalytic activity under UV light irradiation while that containing 4 mol% WO 3 present highest activity under visible light irradiation

  9. Preparation of three dimensional graphene foam–WO3 nanocomposite with enhanced visible light photocatalytic activity

    International Nuclear Information System (INIS)

    Azimirad, R.; Safa, S.

    2015-01-01

    Three dimensional graphene foam (3D GF) was synthesized by chemical vapor deposition (CVD) on a nickel foam skeleton. After dissolving the nickel foam, the obtaining 3D GF was used as a highly porous conductive substrate for nucleation and growth of WO 3 particles. Scanning electron microscopy (SEM) and Raman spectroscopy was employed to ensure the quality of the prepared GFs and to judge about the 3D GF–WO 3 chemical structure. The WO 3 characteristic Raman peaks centered at 726, and 809 cm −1 are slightly broadened and displaced to lower wavelength in the 3D GF–WO 3 nanocomposite, as compared to the corresponding peaks of the bare tungsten oxide. This phenomenon confirms the formation of W–C and W–O–C bonds in composite material which is important for faster transferring the photoexcited electrons to graphene 3D network as an exceptional electron acceptor. The 3D GF−WO 3 composite material was applied in photocatalytic degradation of Rhodamine B dye. It was observed that the annealed samples show an excellent photocatalytic performance relative to the as-prepared 3D GF−WO 3 samples and bare WO 3 , which is ascribed to the lower electron/hole recombination through the formation of W–C and W–O–C bonds. - Highlights: • 3D GF synthesized by CVD on a nickel foam as a highly porous conductive substrate. • WO 3 nanoparticles coated on 3D GF by dip-coating. • 3D GF−WO 3 shows an excellent photocatalytic degradation of Rhodamine B dye. • Better photocatalytic properties assigned to the formation of W–C and W–O–C bonds

  10. CTAB-assisted ultrasonic synthesis, characterization and photocatalytic properties of WO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez-Martínez, D., E-mail: dansanm@gmail.com; Gomez-Solis, C.; Torres-Martinez, Leticia M.

    2015-01-15

    Highlights: • WO{sub 3} 2D nanostructures were synthesized by ultrasound method assisted with CTAB. • WO{sub 3} morphology was mainly of rectangular nanoplates with a thickness of ∼50 nm. • The highest surface area value of WO{sub 3} was obtained to lowest concentration of CTAB. • WO{sub 3} activity was attributed to morphology, surface area and the addition of CTAB. • WO{sub 3} nanoplates were able to causing almost complete mineralization of rhB and IC. - Abstract: WO{sub 3} 2D nanostructures have been prepared by ultrasound synthesis method assisted with CTAB using different molar ratios. The formation of monoclinic crystal structure of WO{sub 3} was confirmed by X-ray powder diffraction (XRD). The characterization of the WO{sub 3} samples was complemented by analysis of scanning electron microscopy (SEM), which revealed morphology mainly of rectangular nanoplates with a thickness of around 50 nm and length of 100–500 nm. Infrared spectroscopy (FT-IR) was used to confirm the elimination of the CTAB in the synthesized samples. The specific surface area was determinate by the BET method and by means of diffuse reflectance spectroscopy (DRS) it was determinate the band-gap energy (E{sub g}) of the WO{sub 3} samples. The photocatalytic activity of the WO{sub 3} oxide was evaluated in the degradation reactions of rhodamine B (rhB) and indigo carmine (IC) under Xenon lamp irradiation. The highest photocatalytic activity was observed in the samples containing low concentration of CTAB with morphology of rectangular nanoplates and with higher surface area value than commercial WO{sub 3}. Photodegradation of rhB and IC were followed by means of UV–vis absorption spectra. The mineralization degree of organic dyes by WO{sub 3} photocatalyst was determined by total organic carbon analysis (TOC) reaching percentages of mineralization of 92% for rhB and 50% for IC after 96 h of lamp irradiation.

  11. The enhanced photoactivity of nanosized Bi2WO6 catalyst for the degradation of 4-chlorophenol

    International Nuclear Information System (INIS)

    Fu Hongbo; Yao Wenqing; Zhang Liwu; Zhu Yongfa

    2008-01-01

    Nanosized Bi 2 WO 6 catalyst exhibited the enhanced photoactivity for the degradation of 4-chlorophenol (4-CP) under visible irradiation compared to the sample prepared by high-temperature solid reaction. The photoactivity of the catalyst was sensitive to pH variation of the suspension. Nanosized Bi 2 WO 6 catalyst showed the highest activity at pH 7.2. The photodegradation of 4-CP by nanosized Bi 2 WO 6 catalyst followed a pseudo-first-order reaction. After three recycling runs for the photodegradation of 4-CP, the activity of the catalyst did not show any significant loss, suggesting that the catalyst was stable under visible irradiation

  12. Polymorphism of tungsten perovskite compounds Ba/sub 2/SEsub(0. 67)WO/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Schittenhelm, H J; Kemmler-Sack, S [Tuebingen Univ. (F.R. Germany). Inst. fuer Anorganische Chemie

    1976-09-01

    The compounds Ba/sub 2/SEsub(0.67)WO/sub 6/ with SE = Gd-Lu are polymorphic. Above 1200/sup 0/C the instable cubic modification (ordered perovskite with 4 formula units Ba/sub 2/SEsub(0.67)vacantsub(0.33)WO/sub 6/ per cell) transforms irreversibly into a hexagonal modification with completely filled cationic lattice. For Ba/sub 2/Eusub(0.67)WO/sub 6/ the transformation is incomplete. With SE = Nd and Sm only the cubic modification is formed.

  13. Neuromorphic transistor achieved by redox reaction of WO3 thin film

    Science.gov (United States)

    Tsuchiya, Takashi; Jayabalan, Manikandan; Kawamura, Kinya; Takayanagi, Makoto; Higuchi, Tohru; Jayavel, Ramasamy; Terabe, Kazuya

    2018-04-01

    An all-solid-state neuromorphic transistor composed of a WO3 thin film and a proton-conducting electrolyte was fabricated for application to next-generation information and communication technology including artificial neural networks. The drain current exhibited a 4-order-of-magnitude increment by redox reaction of the WO3 thin film owing to proton migration. Learning and forgetting characteristics were well tuned by the gate control of WO3 redox reactions owing to the separation of the current reading path and pulse application path in the transistor structure. This technique should lead to the development of versatile and low-power-consumption neuromorphic devices.

  14. Electrodeposition of WO3 nanoparticles into surface mounted metal-organic framework HKUST-1 thin films

    Science.gov (United States)

    Yoo, Hyeonseok; Welle, Alexander; Guo, Wei; Choi, Jinsub; Redel, Engelbert

    2017-03-01

    We describe a novel procedure to fabricate WO3@surface-mounted metal-organic framework (SURMOF) hybrid materials by electrodeposition of WO3 nanoparticles into HKUST-1, also termed Cu3(BTC)2 SURMOFs. These materials have been characterized using x-ray diffraction, time-of-flight secondary ion mass spectrometry, scanning electron microscopy, x-ray photoelectron spectroscopy as well as linear sweep voltammetry. The WO3 semiconductor/SURMOF heterostructures were further tested as hybrid electrodes in their performance for hydrogen evolution reaction from water.

  15. Fabrication and photocatalysis of mesoporous ZnWO4 with PAMAM as a template

    International Nuclear Information System (INIS)

    Lin Shen; Chen Jiebo; Weng Xiulan; Yang Liuyi; Chen Xinqin

    2009-01-01

    Mesoporous ZnWO 4 was prepared with the template of PAMAM. The as-formed samples were characterized by X-ray diffraction (XRD), nitrogen absorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-vis diffuse reflectance spectroscopy (DRS). It is found that the size of pore is in the range of 5-22 nm and that the porosity of ZnWO 4 is composed of aggregated ZnWO 4 nanoparticles. The photocatalytic activities towards degradation of rhodamine B (RhB) and malachite green (MG) under UV light has been investigated. The formation mechanism of mesoporous structures is proposed

  16. Magnetic properties of the strongly correlated chain antiferromagnet KTb(WO4)2

    International Nuclear Information System (INIS)

    Khatsko, E.; Loginov, A.; Cherny, A.; Rykova, A.

    2006-01-01

    The susceptibility and magnetization of a single crystal of KTb(WO 4 ) 2 has been measured in the temperature range 0.5-80 K in magnetic fields up to 6 T. It is shown that KTb(WO 4 ) 2 is an Ising magnet with only one component of the magnetic moment. The three-dimensional phase transition to the antiferromagnetically ordered state has been found below 0.7 K. This transition can be described in the molecular field two-level approximation. The principal exchange constant has been estimated. By using experimental data the magnetic structure of KTb(WO 4 ) 2 is proposed

  17. Tungsten oxide-graphene oxide (WO3-GO) nanocomposite as an efficient photocatalyst, antibacterial and anticancer agent

    Science.gov (United States)

    Jeevitha, G.; Abhinayaa, R.; Mangalaraj, D.; Ponpandian, N.

    2018-05-01

    Functioning of ultrasonically prepared tungsten oxide-graphene oxide (WO3-GO) nanocomposite as a photocatalyst, antibacterial and anticancer system was investigated and the obtained results were compared with that of pure WO3 nanoparticles. Structural, morphological, compositional and optical properties of the prepared WO3 nanoparticles and WO3-GO nanocomposite were studied. Photocatalytic efficiency of the system on organic dyes such as methylene blue (MB, cationic) and indigo carmine (IC, anionic) was investigated. The enhanced efficiency of the WO3-GO nanocomposite system was evaluated under sunlight and compared with that of pure WO3. The degradation efficiency values for MB and IC were found to be 97.03% and 95.43% at 180 and 120 min respectively. Antibacterial activity of the WO3-GO nanocomposite under visible light was tested and improved inhibition results were observed for Escherichia coli and Bacillus subtilis after 6 h of light exposure. The photocatalytic degradation efficiency and antibacterial activity of the WO3-GO nanocomposite are attributed to the improved electron-hole pair separation rate. Investigation on anticancer activity of WO3-GO nanocomposite was tested on human lung cancer (A-549) cell line and the IC50 value was found to be 139.6 ± 4.53 μg/mL. The results obtained in this study may be used as a platform for the development of photocatalysis applications based on WO3-GO nanocomposite.

  18. Experimental and theoretical investigation on photocatalytic activities of 1D Ag/Ag2WO4 nanostructures

    Science.gov (United States)

    Liu, Danqing; Huang, Weicheng; Li, Long; Liu, Lu; Sun, Xiaojun; Liu, Bo; Yang, Bin; Guo, Chongshen

    2017-09-01

    Ag2WO4 is a significant photocatalyst that responds to UV light irradiation only, which greatly hinders it for further practical application for solar light. To address this problem, herein, 1D plasmonic Ag/Ag2WO4 photocatalysts have been fabricated by a successive process including hydrothermal synthesis to obtain Ag2WO4 followed by an additional in situ chemical-reduction process for Ag decoration. Then, the structural features, optical properties, and electronic structures of Ag2WO4 and Ag/Ag2WO4 nanowires were systematically investigated via a combination of theoretical calculations and experimental evidence. The plasmon-enhanced Ag/Ag2WO4 nanowires exhibited higher visible-light-driven photocatalytic activity, which performed a desired photodestruction ratio of 91.2% on methylene blue within 60 min and good stability in five cycles. The Ag decoration greatly facilitates visible-light harvesting and thus promotes photogenerated radical oxidation to dye, which is evidenced by the higher hydroxyl radical level of Ag/Ag2WO4 detected in the ESR test during the photocatalytic process. The theoretical calculation based on density functional theory indicates that Ag nanoparticles formed on the surface of Ag2WO4 could narrow the band gap of Ag2WO4. In addition, the surface plasmon resonance absorption effect and fast charge transfer effect in the metal-semiconductor system contribute to the photocatalytic performance of Ag/Ag2WO4.

  19. WO3 nanorods-modified carbon electrode for sustained electron uptake from Shewanella oneidensis MR-1 with suppressed biofilm formation

    International Nuclear Information System (INIS)

    Zhang, Feng; Yuan, Shi-Jie; Li, Wen-Wei; Chen, Jie-Jie; Ko, Chi-Chiu; Yu, Han-Qing

    2015-01-01

    Highlights: • WO 3 nanorods-modified carbon paper was used as the anode of MFC. • WO 3 nanorods suppressed biofilm growth on the electrode surface. • Sustained electron transfer from cells to electrode via riboflavin was achieved. • C–WO 3 nanorods enable stable and efficient EET process in long-time operation. - Abstract: Carbon materials are widely used as electrodes for bioelectrochemical systems (BES). However, a thick biofilm tends to grow on the electrode surface during continuous operation, resulting in constrained transport of electrons and nutrients at the cell-electrode interface. In this work, we tackled this problem by adopting a WO 3 -nanorods modified carbon electrode (C–WO 3 nanorods), which completely suppressed the biofilm growth of Shewanella Oneidensis MR-1. Moreover, the C–WO 3 nanorods exhibited high electric conductivity and strong response to riboflavin. These two factors together make it possible for the C–WO 3 nanorods to maintain a sustained, efficient process of electron transfer from the MR-1 planktonic cells. As a consequence, the microbial fuel cells with C–WO 3 nanorods anode showed more stable performance than the pure carbon paper and WO 3 -nanoparticles systems in prolonged operation. This work suggests that WO 3 nanorods have the potential to be used as a robust and biofouling-resistant electrode material for practical bioelectrochemical applications

  20. Conductive surface modification of cauliflower-like WO3 and its electrochemical properties for lithium-ion batteries

    International Nuclear Information System (INIS)

    Yoon, Sukeun; Woo, Sang-Gil; Jung, Kyu-Nam; Song, Huesup

    2014-01-01

    Highlights: • Synthesis of cauliflower-like carbon-decorated WO 3 . • Superior cyclability and rate capability for cauliflower-like carbon-decorated WO 3 . • Electrochemical reaction behavior of cauliflower-like carbon-decorated WO 3 with lithium. • In-situ XRD analysis during the first discharge–charge shows a complex reaction of intercalation and conversion of WO 3 . - Abstract: Cauliflower-like WO 3 was synthesized by a hydrothermal reaction without a surfactant, followed by firing, and was investigated as an anode material for lithium-ion battery applications. The scanning electron microscope (SEM) and transmission electron microscope (TEM) characterization indicated that WO 3 nanorods had an aggregation framework and built a cauliflower morphology. With the objective of understanding the charge–discharge process within a voltage range of 0–3 V vs. Li + /Li, in situ X-ray diffraction was used and a complex reaction of intercalation and conversion of WO 3 was revealed for the first time. The cauliflower-like WO 3 after being decorated with carbon provides a high gravimetric capacity of >635 mA h/g (Li 5.5 WO 3 ) with good cycling and a high rate capability when used as an anode in lithium-ion batteries. Based on our studies, we attribute the high electrochemical performance to the nanoscopic WO 3 particles and a conductive carbon layer, which makes them a potential candidate for lithium-ion batteries

  1. Preparation of WO3/g-C3N4 composites and their application in oxidative desulfurization

    Science.gov (United States)

    Zhao, Rongxiang; Li, Xiuping; Su, Jianxun; Gao, Xiaohan

    2017-01-01

    WO3/graphitic carbon nitride (g-C3N4) composites were successfully synthesized through direct calcining of a mixture of WO3 and g-C3N4 at 400 °C for 2 h. The WO3 was prepared by calcination of phosphotungstic acid at 550 °C for 4 h, and the g-C3N4 was obtained by calcination of melamine at 520 °C for 4 h. The WO3/g-C3N4 composites were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and Brunner-Emmett-Teller analysis (BET). The WO3/g-C3N4 composites exhibited stronger XRD peaks of WO3 and g-C3N4 than the WO3 and pure g-C3N4. In addition, two WO3 peaks at 25.7° and 26.6° emerged for the 36% -WO3/g-C3N4 composite. This finding indicated that WO3 was highly dispersed on the surface of the g-C3N4 nanosheets and interacted with the nanosheets, which resulted in the appearance of (012) and (022) planes of WO3. The WO3/g-C3N4 composite also exhibited a larger specific surface area and higher degree of crystallization than WO3 or pure g-C3N4, which resulted in high catalytic activity of the catalyst. Desulfurization experiments demonstrated that the desulfurization rate of dibenzothiophene (DBT) in model oil reached 91.2% under optimal conditions. Moreover, the activity of the catalyst was not significantly decreased after five recycles.

  2. Ethanol vapour sensing properties of screen printed WO3 thick films

    Indian Academy of Sciences (India)

    TECS

    trations. The WO3 thick films exhibit excellent ethanol vapour sensing properties with a maximum sensitivity ... methanol, acetone, isopropanol and acetic acid, have been reported .... maximum sensitivity was obtained at an operating tem-.

  3. Review of WO3 thin film preparation for photoelectrochemical water splitting

    International Nuclear Information System (INIS)

    Ehsan Eftekhari; Mohammad Kassim

    2009-01-01

    Full text: Tungsten trioxide (WO 3 ), which is one of the most essential materials in our daily life has appeared as an excellent photo electrode material for environmental purification. The nano-size of WO 3 thin film water-splitting technology has great potential for environmentally friendly solar-hydrogen production for the future hydrogen economy. There are several methods for producing tungsten oxide film. In this review, we outlined several WO 3 thin film preparation methods such as doctor Bladding, sputtering, layer-by-layer brush painting, spray pyrolysis deposition, sol-gel and other methods. Here we compare the maximum photocurrent obtained, different condition for preparation of WO 3 thin film and characterization outcome. (author)

  4. Eliminating degradation and uncovering ion-trapping dynamics in electrochromic WO3 thin films

    Science.gov (United States)

    Wen, Rui-Tao; Granqvist, Claes G.; Niklasson, Gunnar A.

    2015-01-01

    Amorphous WO3 thin films are of keen interest as cathodic electrodes in transmittance-modulating electrochromic devices. However, these films suffer from ion-trapping-induced degradation of optical modulation and reversibility upon extended Li+-ion exchange. Here, we demonstrate that ion-trapping-induced degradation, which is commonly believed to be irreversible, can be successfully eliminated by constant-current-driven de-trapping, i.e., WO3 films can be rejuvenated and regain their initial highly reversible electrochromic performance. Pronounced ion-trapping occurs when x exceeds ~0.65 in LixWO3 during ion insertion. We find two main kinds of Li+-ion trapping sites (intermediate and deep) in WO3, where the intermediate ones are most prevalent. Li+-ions can be completely removed from intermediate traps but are irreversibly bound in deep traps. Our results provide a general framework for developing and designing superior electrochromic materials and devices. PMID:26259104

  5. AOT-microemulsions-based formation and evolution of PbWO$_{4}$ crystals

    CERN Document Server

    Chen, D; Tang Kai Bin; Liang Zhen Hua; Zheng Hua Gui

    2004-01-01

    Anionic surfactant-AOT-microemulsions-assisted formation and evolution of PbWO//4 nanostructures with bundles rodlike, ellipsoidlike, and spherelike prepared at different media conditions were studied by powder X-ray diffraction pattern, field emission scanning electron microscopy, and transmission electron microscopy. The possible mechanisms for the formation of PbWO//4 samples in series of microemulsion systems were discussed. Various comparison experiments show that several experimental parameters, such as the AOT concentration, the water content, and reaction temperature play important roles in the morphological control of PbWO//4 nanostructures. Room-temperature photoluminescence of PbWO//4 samples with different morphologies has also been investigated and the results reveal that all these samples showed similar features with emissions at 480 similar to 510 nm but different luminescence intensity. 40 Refs.

  6. Degradation of malachite green on Pd/WO3 photocatalysts under simulated solar light

    International Nuclear Information System (INIS)

    Liu Yonggang; Ohko, Yoshihisa; Zhang Ruiqin; YangYingnan; Zhang Zhenya

    2010-01-01

    The photocatalytic degradation of malachite green (MG) dye molecules in aqueous solution was investigated by using palladium (Pd) modified tungsten trioxide (WO 3 ) under simulated solar light. The optimum values for Pd content vs. WO 3 and catalyst concentration in solution for MG (5.0 μmol L -1 ) degradation were 0.5 wt.% and 150 mg L -1 , respectively. The MG concentration change followed the pseudo first order kinetics of the Langmuir-Hinshelwood model. Since MG was also degraded under visible light (λ > 470 nm), which was not absorbed by WO 3 , the mechanism involved both the photocatalytic degradation and self-sensitized degradation of MG. Pd modified WO 3 would be useful as an efficient tool for the decolorization of wastewater under solar light.

  7. Solid-State Electrochromic Device Consisting of Amorphous WO3 and Various Thin Oxide Layers

    Science.gov (United States)

    Shizukuishi, Makoto; Shimizu, Isamu; Inoue, Eiichi

    1980-11-01

    A mixed oxide containing Cr2O3 was introduced into an amorphous WO3 solid-state electrochromic device (ECD) in order to improve its colour memory effect. The electrochromic characteristics were greatly affected by the chemical constituents of a dielectric layer on the a-WO3 layer. Particularly, long memory effect and low power dissipation were attained in a solid-state ECD consisting of a-WO3 and Cr2O3\\cdotV2O5(50 wt.%). Some electrochromic characteristics of the a-WO3/Cr2O3\\cdotV2O5 ECD and the role of V2O5 were investigated.

  8. Analysis of Publication Trends for DOE National Laboratories Comparisons using WoS and Scopus

    Energy Technology Data Exchange (ETDEWEB)

    Springer, Everett P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Milligan, Shelby [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-02

    This report describes: 1) how various laboratories compare in terms of peer-reviewed publications; how the numbers and trends compare between WoS and Scopus; and what research areas have grown or decreased.

  9. SrWO{sub 4} at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Grzechnik, A. [Departamento de Fisica de la Materia Condensada, Universidad del Pais Vasco, Apdo. 644, Bilbao 48080 (Spain); European Synchrotron Radiation Facility, B.P. 220, 38043 Grenoble cedex (France); Crichton, W.A.; Hanfland, M. [European Synchrotron Radiation Facility, B.P. 220, 38043 Grenoble cedex (France)

    2005-11-01

    Room-temperature high-pressure behaviour of SrWO{sub 4} scheelite (I4{sub 1}/a, Z=4) has been studied to 20.7 GPa in a diamond anvil cell using synchrotron angle-dispersive X-ray powder diffraction. Above 10 GPa, it transforms to the fergusonite structure (I2/a, Z=4). Both scheelite and fergusonite types are ordered superstructures of fluorite (Fm anti 3m, Z=4). There is no significant volume collapse at the scheelite-fergusonite phase transition. However, the compression data including both phases of strontium tungstate cannot be fitted by a common Birch-Murnaghan equation of state. An onset of decomposition into component oxides occurs at about 15 GPa. The pressure-induced transformations are irreversible. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Thermal expansion and pressure effect in MnWO4

    International Nuclear Information System (INIS)

    Chaudhury, R.P.; Yen, F.; Cruz, C.R. de la; Lorenz, B.; Wang, Y.Q.; Sun, Y.Y.; Chu, C.W.

    2008-01-01

    MnWO 4 has attracted attention because of its ferroelectric property induced by frustrated helical spin order. Strong spin-lattice interaction is necessary to explain ferroelectricity associated with this type of magnetic order. We have conducted thermal expansion measurements along the a, b, c axes revealing the existence of strong anisotropic lattice anomalies at T 1 =7.8 K, the temperature of the magnetic lock-in transition into a commensurate low-temperature (reentrant paraelectric) phase. The effect of hydrostatic pressure up to 1.8 GPa on the FE phase is investigated by measuring the dielectric constant and the FE polarization. The low-temperature commensurate and paraelectric phase is stabilized and the stability range of the ferroelectric phase is diminished under pressure

  11. Non-uniformity measurements of PbWO4 crystals

    International Nuclear Information System (INIS)

    Depasse, P.; Ernenwein, J.P.; Ille, B.; Martin, F.; Rosset, C.; Zach, F.

    1998-11-01

    Two independent methods have been used to measure the longitudinal non-uniformity scintillation response of 3 different (23-cm long) PbWO 4 crystals. The first one is the classical 60 Co source method. The source is collimated along the crystal, each 1,5-cm, and the scintillation signal is measured with a photomultiplier (a hybrid photomultiplier in our case). The second one is the use of cosmic particles (Minimum Ionizing Particles). A cosmic bench allows reconstructing the track of the MIP's and thus the energy deposit with the help of a full GEANT simulation of the setup. Variations of E along the crystal artificially cut in 1,5-cm divisions, leads to determine the non-uniformity. The conclusion is that both methods agree quite well. Furthermore, a good estimation of crystal light yield can be obtained. (author)

  12. [Doctor's degree thesis of Tomasz Adolf Wołkowiński "Carditidis rheumaticae historia"].

    Science.gov (United States)

    Stembrowicz, W

    2001-01-01

    In 1817 on the University of Vilnius Faculty of Medicine, T. A. Wołkowiński, a student of the eminent clinician Józef Frank, defended his doctor's degree thesis about a direct relation between rheumatic disease and cardiomegaly. It was probably the first paper in Poland describing with details the rheumatic heart disease. Unfortunately we don't know much about T. A. Wołkowiński's life.

  13. Study on light output and energy resolution of PbWO4 crystal

    International Nuclear Information System (INIS)

    Su Guanghui; Yue Ke; Sun Zhiyu

    2010-01-01

    The light output and energy resolution of PbWO 4 crystal are studied with different wrapping materials and methods. The Wrapping condition was optimized by analyzing the experimental data to gain higher light output and better energy resolution. A GEANT4-based package has been developed to simulate the corresponding features of PbWO 4 crystal, and the simulation results are consistent with the experimental data. (authors)

  14. Light-Driven Au-WO3@C Janus Micromotors for Rapid Photodegradation of Dye Pollutants.

    Science.gov (United States)

    Zhang, Qilu; Dong, Renfeng; Wu, Yefei; Gao, Wei; He, Zihan; Ren, Biye

    2017-02-08

    A novel light-driven Au-WO 3 @C Janus micromotor based on colloidal carbon WO 3 nanoparticle composite spheres (WO 3 @C) prepared by one-step hydrothermal treatment is described. The Janus micromotors can move in aqueous media at a speed of 16 μm/s under 40 mW/cm 2 UV light due to diffusiophoretic effects. The propulsion of such Au-WO 3 @C Janus micromotors (diameter ∼ 1.0 μm) can be generated by UV light in pure water without any external chemical fuels and readily modulated by light intensity. After depositing a paramagnetic Ni layer between the Au layer and WO 3 , the motion direction of the micromotor can be precisely controlled by an external magnetic field. Such magnetic micromotors not only facilitate recycling of motors but also promise more possibility of practical applications in the future. Moreover, the Au-WO 3 @C Janus micromotors show high sensitivity toward extremely low concentrations of sodium-2,6-dichloroindophenol (DCIP) and Rhodamine B (RhB). The moving speed of motors can be significantly accelerated to 26 and 29 μm/s in 5 × 10 -4 wt % DCIP and 5 × 10 -7 wt % RhB aqueous solutions, respectively, due to the enhanced diffusiophoretic effect, which results from the rapid photocatalytic degradation of DCIP and RhB by WO 3 . This photocatalytic acceleration of the Au-WO 3 @C Janus micromotors confirms the self-diffusiophoretic mechanism and opens an opportunity to tune the motility of the motors. This work also offers the light-driven micromotors a considerable potential for detection and rapid photodegradation of dye pollutants in water.

  15. Preparation of WO3/g-C3N4 composites and their application in oxidative desulfurization

    International Nuclear Information System (INIS)

    Zhao, Rongxiang; Li, Xiuping; Su, Jianxun; Gao, Xiaohan

    2017-01-01

    Highlights: • The WO 3 /g-C 3 N 4 was successfully synthesized through simple calcination. • The process is simple and the cost raw materials is cheap. • The WO 3 /g-C 3 N 4 firstly applied to ODS. • The desulpurization rate of WO 3 /g-C 3 N 4 may attach to 91.2%. • Five recycles of WO 3 /g-C 3 N 4 still attach to 89.5% due to heterogeneous catalysis. - Abstract: WO 3 /graphitic carbon nitride (g-C 3 N 4 ) composites were successfully synthesized through direct calcining of a mixture of WO 3 and g-C 3 N 4 at 400 °C for 2 h. The WO 3 was prepared by calcination of phosphotungstic acid at 550 °C for 4 h, and the g-C 3 N 4 was obtained by calcination of melamine at 520 °C for 4 h. The WO 3 /g-C 3 N 4 composites were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and Brunner−Emmett−Teller analysis (BET). The WO 3 /g-C 3 N 4 composites exhibited stronger XRD peaks of WO 3 and g-C 3 N 4 than the WO 3 and pure g-C 3 N 4 . In addition, two WO 3 peaks at 25.7° and 26.6° emerged for the 36% −WO 3 /g-C 3 N 4 composite. This finding indicated that WO 3 was highly dispersed on the surface of the g-C 3 N 4 nanosheets and interacted with the nanosheets, which resulted in the appearance of (012) and (022) planes of WO 3 . The WO 3 /g-C 3 N 4 composite also exhibited a larger specific surface area and higher degree of crystallization than WO 3 or pure g-C 3 N 4 , which resulted in high catalytic activity of the catalyst. Desulfurization experiments demonstrated that the desulfurization rate of dibenzothiophene (DBT) in model oil reached 91.2% under optimal conditions. Moreover, the activity of the catalyst was not significantly decreased after five recycles.

  16. Photoelectrochemical solar cells based on Bi{sub 2}WO{sub 6}; Celdas solares fotoelectroquimicas basadas en Bi{sub 2}WO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Madriz, Lorean; Tata, Jose; Cuartas, Veronica; Cuellar, Alejandra; Vargas, Ronald, E-mail: lmadriz@usb.ve [Departamento de Quimica, Universidad Simon Bolivar, Caracas (Venezuela, Bolivarian Republic of)

    2014-04-15

    In this study, photoelectrochemical solar cells based on bismuth tungstate electrodes were evaluated. Bi{sub 2}WO{sub 6} was synthesized by a hydrothermal method and characterized by scanning electron microscopy, UV-Vis reflectance spectroscopy, and X-ray powder diffraction. For comparison, solar cells based on TiO{sub 2} semiconductor electrodes were evaluated. Photoelectrochemical response of Grätzel-type solar cells based on these semiconductors and their corresponding sensitization with two inexpensive phthalocyanines dyes were determined. Bi{sub 2}WO{sub 6}-based solar cells presented higher values of photocurrent and efficiency than those obtained with TiO{sub 2} electrodes, even without sensitization. These results portray solar cells based on Bi{sub 2}WO{sub 6} as promising devices for solar energy conversion owing to lower cost of production and ease of acquisition. (author)

  17. WO3 Nanowires on Graphene Sheets as Negative Electrode for Supercapacitors

    Directory of Open Access Journals (Sweden)

    Bo Liu

    2017-01-01

    Full Text Available WO3 nanowires directly grown on graphene sheets have been fabricated by using a seed-mediated hydrothermal method. The morphologies and electrochemical performance of WO3 films prepared by different process were studied. The results show that the precoated nanoseeds and graphene sheets on graphite electrode provide more reactive centers for the nucleation and formation of uniform WO3 nanowires. The WO3 nanowires electrode exhibits a high area specific capacitance of 800 mF cm−2 over negative potential range from −1.0 V to 0 V versus SCE in 1 M Li2SO4 solution. A high performance electrochemical supercapacitor assembled with WO3 nanowires as negative electrode and PANI/MnO2 as positive electrodes over voltage range of 1.6 V displays a high volumetric capacitance of 2.5 F cm−3, which indicate great potential applications of WO3 nanowires on graphene sheets as negative electrode for energy storage devices.

  18. WO3 nanoflakes decorated with CuO clusters for enhanced photoelectrochemical water splitting

    Directory of Open Access Journals (Sweden)

    Chongwu Wang

    2018-04-01

    Full Text Available The low quantum efficiency arising from poor charges transfer and insufficient light absorption is one of the critical challenges toward achieving highly efficient water splitting in photoelectrochemical cells. Three dimensions (3D structures and heterojunctions have received intensive research interests recent years due to their excellent ability to separate photo-generated charges as well as the enhanced light harvesting property. Herein, 3D CuO/WO3 structure was fabricated through a facile solvothermal method followed by chemical bath deposition. The loading of CuO clusters on WO3 nanoflake arrays results in a much improved photocurrent density compared with that of pristine WO3 nanoflake arrays, which reaches 1.8 mA/cm2 at 1.23 V vs. the reversible hydrogen electrode. The electrochemical impedance spectroscopy measurement demonstrates that the improved performance of CuO/WO3 electrode is attributed to the accelerated charge transfer kinetics as a result of the desirable band alignment in CuO/WO3 heterojunction. This work demonstrates a facile strategy to construct superior WO3 electrode, which will ultimately allow for efficient storage of solar energy into hydrogen. Keywords: Photoelectrochemistry, Water splitting, Tungsten trioxide photoanode, CuO clusters, Heterojunction

  19. A Resistive Humidity Sensor Based on Nanostructured WO3-ZnO Composites

    Directory of Open Access Journals (Sweden)

    Karunesh Tiwari

    2011-11-01

    Full Text Available Paper reports morphological and humidity sensing studies of WO3 and WO3-ZnO composite pellets prepared in the weight % ratio of 10:1, 4:1 and 2:1 by solid-state reaction route. The pellets have been annealed at temperatures of 300-500 °C. XRD pattern shows peaks of ZnWO4 formed due to solid state reaction between WO3 and ZnO. SEM micrographs show that the sensing elements manifest porous structure. Granulation and tendency to agglomerate seen in the SEM micrograph are due to the presence of zinc ions in ZnWO4. Nanoparticles are having their sizes in the range 37-182 nm. The average Kelvin radius at 20˚C room temperature is 27 Ả. Humidity sensing application of the pellets has been studied in a humidity control cabinet. It is observed that as relative humidity increases, there is decrease in the resistance of pellets in the range 10-85 % RH. Sensing element of WO3-ZnO in 2:1 weight % ratio shows best results in 10-85 % relative humidity range. The average sensitivity of this sample is 1.25 MΩ/%RH. This sensing element shows good reproducibility, low hysteresis and less effect of aging.

  20. Synthesis, characterization and liquefied petroleum gas (LPG) sensing properties of WO3 nano-particles

    Science.gov (United States)

    Singh, Subhash; Majumder, S. B.

    2018-05-01

    Metal oxide sensors, such as ZnO, SnO2, and WO3 etc. have been utilized for several decades for low-costd etection of combustible and toxic gases. In the present work tungsten oxide (WO3) nanoparticles have been prepared by using an economic wet chemical synthesis route. To understand the phase formation behavior of the synthesized powders, X-ray diffraction analysis has been performed. The microstructure evolution of the synthesized powders was characterized by field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The calcined phase pure WO3 nanoparticles are investigated in terms of LPG gas sensing properties. The gas sensing measurements has been done in two different mode of operation (namely static and dynamic measurements). The degree of oxygen deficiency in the WO3 sensor also affected the sensor properties and the optimum oxygen content of WO3 was necessary to get high sensitivity for LPG. The WO3 sensor shows the excellent sensor properties for LPG at the operating temperature of 250°C.

  1. Tungsten-based nanomaterials (WO{sub 3} & Bi{sub 2}WO{sub 6}): Modifications related to charge carrier transfer mechanisms and photocatalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Girish Kumar, S., E-mail: girichem@yahoo.co.in; Koteswara Rao, K.S.R., E-mail: raoksrk@gmail.com

    2015-11-15

    Graphical abstract: - Highlights: • Photocatalytic applications of WO{sub 3} and Bi{sub 2}WO{sub 6} based nanomaterial are reviewed. • Modifications to improve their performance are highlighted. • Charge carrier generation–separation–recombination is discussed. • Challenges and future prospects in this area are addressed. - Abstract: Heterogeneous photocatalysis is an ideal green energy technology for the purification of wastewater. Although titania dominates as the reference photocatalyst, its wide band gap is a bottleneck for extended utility. Thus, search for non-TiO{sub 2} based nanomaterials has become an active area of research in recent years. In this regard, visible light absorbing polycrystalline WO{sub 3} (2.4–2.8 eV) and Bi{sub 2}WO{sub 6} (2.8 eV) with versatile structure-electronic properties has gained considerable interest to promote the photocatalytic reactions. These materials are also explored in selective functional group transformation in organic reactions, because of low reduction and oxidation potential of WO{sub 3} CB and Bi{sub 2}WO{sub 6} VB, respectively. In this focused review, various strategies such as foreign ion doping, noble metal deposition and heterostructuring with other semiconductors designed for efficient photocatalysis is discussed. These modifications not only extend the optical response to longer wavelengths, but also prolong the life-time of the charge carriers and strengthen the photocatalyst stability. The changes in the surface-bulk properties and the charge carrier transfer dynamics associated with each modification correlating to the high activity are emphasized. The presence of oxidizing agents, surface modification with Cu{sup 2+} ions and synthesis of exposed facets to promote the degradation rate is highlighted. In depth study on these nanomaterials is likely to sustain interest in wastewater remediation and envisaged to signify in various green energy applications.

  2. Facile synthesis of reduced graphene oxide/CoWO4 nanocomposites with enhanced electrochemical performances for supercapacitors

    International Nuclear Information System (INIS)

    Xu, Xiaowei; Shen, Jianfeng; Li, Na; Ye, Mingxin

    2014-01-01

    Highlights: • RGO/CoWO 4 composites were successfully prepared through a facile hydrothermal method. • RGO/CoWO 4 composites show much higher specific capacitances than pure CoWO 4 . • Enhanced electrical conductivity leads to superior electrochemical performance. - Abstract: A facile one-pot hydrothermal method was provided for synthesis of the reduced graphene oxide-cobalt tungstate (RGO/CoWO 4 ) nanocomposites with the enhanced electrochemical performances for supercapacitors for the first time. The resulting nanocomposites are comprised of CoWO 4 nanospheres that are well-anchored on graphene sheets by in situ reducing. The prepared RGO/CoWO 4 nanocomposites have been thoroughly characterized by Fourier–transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, Thermogravimetric analysis, Scanning electron microscopy, Transmission electron microscopy, X-ray photoelectron spectroscopy, and N 2 adsorption–desorption. Importantly, the prepared nanocomposites exhibit superior electrochemical performance to CoWO 4 as electrodes for supercapacitors. As a result, RGO/CoWO 4 nanocomposites with 91.6 wt% CoWO 4 content achieved a specific capacitance about 159.9 F g −1 calculated from the CV curves at 5 mV s −1 , which was higher than that of CoWO 4 (60.6 F g −1 ). The good electrochemical performance can be attributed to the increased electrical conductivity and the creation of new active sites due to the synergetic effect of RGO and CoWO 4 nanospheres. The cyclic stability tests demonstrated capacitance retention of about 94.7% after 1000 cycles, suggesting the potential application of RGO/CoWO 4 nanocomposites in energy-storage devices

  3. Morphology-controlled synthesis of CdWO4 nanorods and nanoparticles via a molten salt method

    International Nuclear Information System (INIS)

    Wang Yonggang; Ma Junfeng; Tao Jiantao; Zhu Xiaoyi; Zhou Jun; Zhao Zhongqiang; Xie Lijin; Tian Hua

    2006-01-01

    Cadmium tungstate (CdWO 4 ) nanoparticles and nanorods have been successfully synthesized by a molten salt method at 270 deg. C, and the morphology of the nanocrystals can be controlled by adjusting such reaction conditions as the calcined time and the weight ratio of the salt to the CdWO 4 precursor. The resultant sample is a pure phase of CdWO 4 without any other impurities

  4. Pt supported self-assembled nest-like-porous WO3 hierarchical microspheres as electrocatalyst for methanol oxidation

    International Nuclear Information System (INIS)

    Zhang, Jun; Tu, Jiang-ping; Du, Gao-hui; Dong, Zi-min; Su, Qing-mei; Xie, Dong; Wang, Xiu-li

    2013-01-01

    Highlights: ► Nest-like-porous (NLP) WO 3 microspheres are assembled by a hydrothermal method. ► The NLP-WO 3 microspheres have a hexagonal structure and high porous surface. ► Great enhancement of electrochemical property is achieved for Pt/NLP-WO 3 microspheres. -- Abstract: Hexagonal tungsten trioxide (hex-WO 3 ) hierarchical microspheres with nest-like pores are synthesized by a facile hydrothermal method. The nest-like-porous (NLP) WO 3 hierarchical microspheres with 5–6 μm in diameters are self-assembled of single-crystal nanowires. The nanowires have lengths of several hundred nanometers and diameters of 5–30 nm; the long axis of nanowire is oriented toward 〈0 0 1〉 direction. The specific surface area of hex-WO 3 microspheres is 62 m 2 g −1 . 20 wt.% Pt nanoparticles with ∼7 nm are loaded onto the WO 3 microspheres using a conventional microwave-assisted ethylene glycol (EG) method. The electrocatalytic activity for methanol oxidation of Pt/NLP-WO 3 microspheres is investigated by cyclic voltammetry and chronoamperometry. Due to the large tunnels of hexagonal structure and high porous surface morphology, great enhancement of electrochemical performance is achieved. The Pt/NLP-WO 3 microspheres are demonstrated to be a promising anode material for direct methanol fuel cells (DMFC)

  5. Degradation of organic dyes using spray deposited nanocrystalline stratified WO3/TiO2 photoelectrodes under sunlight illumination

    Science.gov (United States)

    Hunge, Y. M.; Yadav, A. A.; Mahadik, M. A.; Bulakhe, R. N.; Shim, J. J.; Mathe, V. L.; Bhosale, C. H.

    2018-02-01

    The need to utilize TiO2 based metal oxide hetero nanostructures for the degradation of environmental pollutants like Rhodamine B and reactive red 152 from the wastewater using stratified WO3/TiO2 catalyst under sunlight illumination. WO3, TiO2 and stratified WO3/TiO2 catalysts were prepared by a spray pyrolysis method. It was found that the stratified WO3/TiO2 heterostructure has high crystallinity, no mixed phase formation occurs, strong optical absorption in the visible region of the solar spectrum, and large surface area. The photocatalytic activity was tested for degradation of Rhodamine B (Rh B) and reactive red 152 in an aqueous medium. TiO2 layer in stratified WO3/TiO2 catalyst helps to extend its absorption spectrum in the solar light region. Rh B and Reactive red 152is eliminated up to 98 and 94% within the 30 and 40 min respectively at optimum experimental condition by stratified WO3/TiO2. Moreover, stratified WO3/TiO2 photoelectrode has good stability and reusability than individual TiO2 and WO3 thin film in the degradation of Rh B and reactive red 152. The photoelectrocatalytic experimental results indicate that stratified WO3/TiO2 photoelectrode is a promising material for dye removal.

  6. Humidity sensing properties of WO3 thick film resistor prepared by screen printing technique

    International Nuclear Information System (INIS)

    Garde, Arun S

    2014-01-01

    Highlights: • Polycrystalline WO 3 Thick films are fabricated by screen printing technique. • Monoclinic phases were the majority in formation of films. • The peak at 1643 cm −1 shows stretching vibrations attributed to W-OH of adsorbed H 2 O. • Absorption peaks in the range 879–650 cm −1 are attributed to the stretching W-O-W bonds. • Increase in resistance with decrease in RH when exposed to 20–100% RH. - Abstract: Thick films of tungsten oxide based were prepared using standard screen printing technique. To study the effect of temperature on the thick films were fired at different temperature for 30 min in air atmosphere. The WO 3 thick films were characterized with X-ray diffraction, scanning electron microscopy and EDAX for elemental analysis. The formation of mixed phases of the film together with majority of monoclinic phase was observed. IR spectra confirm the peak at 1643 cm −1 clearly shows stretching vibrations attributed to the W-OH bending vibration mode of the adsorbed water molecules. The absorption peaks in the range 879–650 cm −1 are attributed to the stretching W-O-W bonds (i.e. ν [W-O inter -W]). The peak located at 983 cm −1 belong to W=O terminal of cluster boundaries. A change in the resistance was observed with respect to the relative humidity when the WO 3 thick films were exposed to a wide humidity range of 20–100%. An increasing firing temperature of WO 3 film increases with the sensitivity. The parameters such as sensitivity and hysteresis of the WO 3 film sensors have been evaluated

  7. WO-Type Wolf-Rayet Stars: the Last Hurrah of the Most Massive Stars?

    Science.gov (United States)

    Massey, Philip

    2014-10-01

    WO-type Wolf-Rayet (WR) stars are considered the final evolutionary stage of the highest mass stars, immediate precursors to Type Ic (He-poor) core-collapse supernovae. These WO stars are rare, and until recently only 6 were known. Our knowledge about their physical properties is mostly based on a single object, Sand 2 in the LMC. It was the only non-binary WO star both bright and unreddened enough that its FUV and NUV spectra could be obtained by FUSE and HST/FOS. A non-LTE analysis showed that Sand 2 is very hot and its (C+O)/He abundance ratio is higher than that found in WC-type WRs, suggesting it is indeed highly evolved. However, the O VI resonance doublet in the FUV required a considerably cooler temperature (120,000 K) model than did the optical O VI lines (170,000 K). Further, the enhanced chemical abundances did not match the predictions of stellar evolutionary models. Another non-LTE study found a 3x higher (C+O)/He abundance ratio and a cooler temperature. We have recently discovered two other bright, single, and lightly reddened WOs in the LMC, allowing us to take a fresh look at these important objects. Our newly found WOs span a range in excitation type, from WO1 (the highest) to WO4 (the lowest). Sand 2 is intermediate (WO3). We propose to use COS to obtain FUV and NUV data of all three stars for as comprehensive a study as is currently possible. These UV data will be combined with our optical Magellan spectra for a detailed analysis with CMFGEN with the latest atomic data. Knowing the degree of chemical evolution of these WO stars is crucial to determining their evolutionary status, and thus in understanding the final stages of the most massive stars.

  8. On tungstates of divalent cations (II). Polymorphy of Pb{sub 2}WO{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Jantz, Stephan G.; Dialer, Marwin; Hoeppe, Henning A. [Lehrstuhl fuer Festkoerperchemie, Universitaet Augsburg (Germany); Pielnhofer, Florian [Abteilung Nanochemie, Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany)

    2017-12-13

    The phase transition from the low temperature form Pb{sub 2}[WO{sub 5}] to its high temperature form Pb{sub 2}O[WO{sub 4}] was monitored by means of temperature dependent powder XRD. Single-crystals of Pb{sub 2}[WO{sub 5}], suitable for a structure determination by single-crystal X-ray diffraction, were obtained by quenching a sample from 500 C to room temperature. The low-temperature phase Pb{sub 2}[WO{sub 5}] comprises the structural motive of infinite zigzag chains built by cornersharing WO{sub 6} octahedra, known from the tungstates M{sub 2}[WO{sub 5}] (M = Sr, Ba), but crystallizes in a new structure type [C2/c, a = 14.0996(4) Aa, b = 5.8579(2) Aa, c = 12.6877(4) Aa, β = 114.3569(13) , Z = 8, R{sub int} = 0.042, R{sub 1} = 0.040, wR{sub 2} = 0.068]. The crystal structure of the high-temperature phase Pb{sub 2}O[WO{sub 4}] [C2/m, a = 14.2126(4) Aa, b = 5.80150(10) Aa, c = 7.3477(2) Aa, β = 113.9402(7) , Z = 4, R{sub 1} = 0.035, wR{sub 2} = 0.055] is revised, based on single-crystal XRD data. Furthermore spectroscopic data (IR, Raman and UV/Vis spectra) are presented. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Evaluate humidity sensing properties of novel TiO2–WO3 composite material

    International Nuclear Information System (INIS)

    Lin, Wang-De; Lai, De-Sheng; Chen, Min-Hung; Wu, Ren-Jang; Chen, Fu-Chou

    2013-01-01

    Graphical abstract: TiO 2 –WO 3 (1:1) showed better humidity sensing properties than others within the range of 12–90% relative humidity (RH), the response and recovery time were about 20 s and 160 s, respectively. Compared to the previous studies, the prepared sensor exhibits higher sensitivity (S = 451) and the low hysteresis value was around 0.13% at 32% RH. - Highlights: • Novel TiO 2 –WO 3 composite material was prepared for humidity sensor. • The sensor exhibits higher sensitivity (S = 451). • Low hysteresis value was around 0.13% at 32% RH. - Abstract: A novel TiO 2 –WO 3 composite material was prepared using a different proportion of TiO 2 and WO 3 to that investigated in previous studies. The obtained mesoporous material was characterized using X-ray diffraction, Fourier transform infrared spectrometry, transmission electron microscopy, energy dispersive X-ray spectroscopy, and N 2 adsorption-desorption techniques. The humidity-sensing properties were measured using an inductance, capacitance and resistance analyzer. The results demonstrated that the TiO 2 –WO 3 sample with a ratio of 1:1 showed better humidity sensing properties. Compared to previous studies, the prepared sensor exhibited higher sensitivity (S = 451) and the lower hysteresis value was around 0.13% at 32% RH. Complex impedance analysis indicated that the enhanced humidity sensitivity was probably due to spherical Brunauer–Emmett–Teller surface area and the hetero-junction between TiO 2 –WO 3 thin films, while the impedance varied about three orders of magnitude. Our results demonstrated the potential application of TiO 2 –WO 3 composite for fabricating high performance humidity sensors

  10. Preparation of tungsten coatings on graphite by electro-deposition via Na2WO4–WO3 molten salt system

    International Nuclear Information System (INIS)

    Sun, Ning-bo; Zhang, Ying-chun; Jiang, Fan; Lang, Shao-ting; Xia, Min

    2014-01-01

    Highlights: • Tungsten coatings on graphite were firstly obtained by electro-deposition method via Na 2 WO 4 –WO 3 molten salt system. • Uniform and dense tungsten coatings could be easily prepared in each face of the sample, especially the complex components. • The obtained tungsten coatings are with high purity, ultra-low oxygen content (about 0.022 wt%). • Modulate pulse parameters can get tungsten coatings with different thickness and hardness. - Abstract: Tungsten coating on graphite substrate is one of the most promising candidate materials as the ITER plasma facing components. In this paper, tungsten coatings on graphite substrates were fabricated by electro-deposition from Na 2 WO 4 –WO 3 molten salt system at 1173 K in atmosphere. Tungsten coatings with no impurities were successfully deposited on graphite substrates under various pulsed current densities in an hour. By increasing the current density from 60 mA cm −2 to 120 mA cm −2 an increase of the average size of tungsten grains, the thickness and the hardness of tungsten coatings occurs. The average size of tungsten grains can reach 7.13 μm, the thickness of tungsten coating was in the range of 28.8–51 μm, and the hardness of coating was higher than 400 HV. No cracks or voids were observed between tungsten coating and graphite substrate. The oxygen content of tungsten coating is about 0.022 wt%

  11. Structural, vibrational and luminescence properties of the (1−x)CaWO{sub 4}−xCdWO{sub 4} system

    Energy Technology Data Exchange (ETDEWEB)

    Taoufyq, A. [Institut Matériaux Microélectronique et Nanosciences de Provence, Aix Marseille Université, CNRS, Université de Toulon, IM2NP UMR 7334, 83957, La Garde (France); Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir, Maroc (Morocco); CEA/DEN, Département d’Études des Réacteurs, Laboratoire Dosimétrie Capteurs Instrumentation, CEA Cadarache, 13108, Saint-Paul-lez-Durance (France); Société CESIGMA, Signals and Systems, 1576 Chemin de La Planquette, 83130 La Garde (France); Guinneton, F.; Valmalette, J-C.; Arab, M. [Institut Matériaux Microélectronique et Nanosciences de Provence, Aix Marseille Université, CNRS, Université de Toulon, IM2NP UMR 7334, 83957, La Garde (France); Benlhachemi, A.; Bakiz, B. [Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir, Maroc (Morocco); Villain, S. [Institut Matériaux Microélectronique et Nanosciences de Provence, Aix Marseille Université, CNRS, Université de Toulon, IM2NP UMR 7334, 83957, La Garde (France); and others

    2014-11-15

    In the present work, we investigate the structural, microstructural, vibrational and luminescence properties of the system (1−x)CaWO{sub 4}−xCdWO{sub 4} with x ranging between 0 and 1. Polycrystalline samples were elaborated using a coprecipitation technique followed by thermal treatment at 1000 °C. The samples were then characterized using X-ray diffraction, scanning electron microscopy, Raman spectroscopy and luminescence analyses. X-ray diffraction profile analyses using Rietveld method showed that two kinds of solid solutions Ca{sub 1−x}Cd{sub x}WO{sub 4} having scheelite and wolframite structures, with respectively tetragonal and monoclinic crystal cells, were observed, with a biphasic system for compositions x=0.6 and 0.7. The scanning electron microscopy experiments showed a complex evolution of morphologies and crystallite sizes as x increased. The vibration modes of Raman spectra were characteristic of composition-dependent disordered solid solutions with decreasing wavenumbers as x increased. Luminescence experiments were performed under UV-laser light irradiation. The energies of emission bands increased linearly with cadmium composition x. The integrated intensity of luminescence reached a maximum value for the substituted wolframite phase with composition x=0.8. - Graphical abstract: Luminescence on UV excitation (364.5 nm) of (1−x)CaWO{sub 4−x}CdWO{sub 4} system, elaborated from coprecipitation technique at 1000 °C, with 0WO{sub 4} polycrystalline phases with 0≤x≤0.5. (b) Maximum of luminescence intensity for the composition x=0.8. - Highlights: • Solid solutions Ca{sub 1−x}Cd{sub x}WO{sub 4} are elaborated from coprecipitation technique. • The structures of two types of solid solutions are refined using Rietveld method. • A maximum of luminescence is obtained for an intermediate composition x=0.8.

  12. Investigation of the La2O3-Nb2O5-WO3 ternary phase diagram: Isolation and crystal structure determination of the original La3NbWO10 material

    KAUST Repository

    Vu, T.D.; Vu, T.D.; Barre, M.; Adil, Karim; Jouanneaux, A.; Suard, E.; Goutenoire, F.

    2015-01-01

    In the course of the exploration of the La2O3-WO3-Nb2O5 ternary phase diagram, a new compound with the formula La3NbWO10 was discovered. Its structure was determined from a combination of powder X-ray and neutron diffraction data. It crystallizes

  13. Reduced graphene oxide/δ-WO{sub 3} composites for volatile organic compounds sensing

    Energy Technology Data Exchange (ETDEWEB)

    Perfecto, Tarcisio Micheli; Zito, Cecilia de Almeida; Volanti, Diogo Paschoalini, E-mail: tarcisio93@hotmail.com [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Sao Paulo, SP (Brazil)

    2016-07-01

    Full text: Metal oxide semiconductors (MOS) is a simple and low-cost alternative to detect volatile organic compounds (VOCs) with fast response and recovery time [1]. In this context, reduced graphene oxide (RGO) is used in order to achieve a superior metal oxides gas sensing performance [2]. Thus, we report the synthesis of RGO/δ-WO{sub 3} composites by microwave-assisted hydrothermal method and its application in VOCs detection. The composites were prepared in a single-step using a graphene oxide dispersion, tungsten salt, ammonium oxalate hydrate as morphological control agent, and HCl in aqueous medium. The mixture was sealed in an autoclave and irradiated by microwave (800W) at 140 °C for 10 minutes. Then the sample was heating treatment at 400 °C for 1 hour. δ-WO{sub 3} single phase was also prepared by the same process without graphene oxide. The XRD results indicated the successful formation of triclinic phase of WO{sub 3} for both samples. FEG-SEM images showed the δ-WO{sub 3} nanoplates formation that are agglomerated and become more disperse and with irregular shape in RGO/δ-WO{sub 3} composite. TEM analysis revealed the interaction between RGO and δ-WO{sub 3} particles. The preliminary gas sensing results showed that increasing the operation temperature, more sensitive the composite RGO/δ-WO{sub 3} was toward the ethanol, methanol, acetone, toluene and benzene. So far, the highest response observed was to acetone at 300 °C. The response of RGO/δ-WO{sub 3} to 5, 10, 50, 100 and 200 ppm of acetone was 1.08, 1.12, 1.42, 1.75, and 1.99, respectively. We expect that increasing the operating temperature, more sensitive the material will become, since reports shows that WO{sub 3} sensors exhibit higher responses at higher temperatures [3]. Acknowledgments: The authors acknowledge FAPESP grants: 16/04371-1, 15/04306-2 and 14/17343-0. Refs.: [1] Jiang, D.;et al. RSC Adv. 2015, 5 (49), 39442-39448. [2] Jie, X.; et al. Sensors Actuators B Chem. 2015, 220

  14. Ethylene Separation via Hydrate Formation in W/O Emulsions

    Directory of Open Access Journals (Sweden)

    Yong Pan

    2015-05-01

    Full Text Available An hybrid absorption-hydration method was adopted to recover C2H4 from C2H4/CH4 binary gas mixtures and the hydrate formation conditions of C2H4/CH4 mixtures was studied experimentally in diesel in water (w/o emulsions. Span 20 at a concentration of 1.0 wt% in the aqueous phase was added to form water in diesel emulsions before hydrate formation and then hydrate in diesel slurry was separated after hydrate formation. The influences of initial gas-liquid volume ratio (53–142, pressure (3.4–5.4 MPa, temperature (274.15–278.15 K, water cuts (10–30 vol%, and the mole fraction of C2H4 in feed gas (13.19–80.44 mol% upon the C2H4 separation efficiency were systematically investigated. The experimental results show that ethylene can be enriched in hydrate slurry phase with high separation factor (S and recovery ratio (R. Most hydrate formation finished in 20 min, after that, the hydrate formation rate became very slow. The conclusion is useful for determining the suitable operation conditions when adopting an absorption-hydration method to separate C2H4/CH4.

  15. Production of CaWO{sub 4} crystals for direct dark matter search with CRESST

    Energy Technology Data Exchange (ETDEWEB)

    Muenster, Andrea [Physik-Department and Excellence Cluster Universe, Technische Universitaet Muenchen, D-85748 Garching (Germany); Collaboration: CRESST-Collaboration

    2016-07-01

    The direct dark matter search experiment CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) uses scintillating CaWO{sub 4} single crystals as targets for possible recoils of dark matter particles. Since several years these CaWO{sub 4} crystals are produced directly at the Technische Universitaet Muenchen (TUM) including the CaWO{sub 4} powder production from the raw materials CaCO{sub 3} and WO{sub 3}, the CaWO{sub 4} crystal growth via the Czochralski method as well as the after-growth treatment of the crystals. In the recently finished CRESST-II Phase 2 (2013-2015), 4 TUM-grown crystals were installed in the main cryostat for the first time. Showing one of the best radiopurities of all installed crystals combined with an excellent detector performance the analysis of the crystal TUM40 resulted in the best sensitivity for low-mass dark matter particles in 2014. For the upcoming CRESST-III phase 2 we aim for a further improvement in radiopurity by a factor of 100. First results of a chemical purification of the raw materials as well as future plans to reduce the intrinsic background via recrystallization are presented.

  16. Non-stoichiometry defects and radiation hardness of lead tungstate crystals PbWO sub 4

    CERN Document Server

    Devitsin, E G; Potashov, S Yu; Terkulov, A R; Nefedov, V A; Polyansky, E V; Zadneprovski, B I; Kjellberg, P; Korbel, V

    2002-01-01

    It has been stated many times that the formation of radiation infringements in PbWO sub 4 is to a big extent stipulated by the non-stoichiometry defects of the crystals, arising in the process of their growth and annealing. To refine the idea of characteristics of the non-stoichiometry defects and their effect on the radiation hardness of PbWO sub 4 , the current study is aimed at the melt composition infringements during its evaporation and at optical transmission of crystals obtained in these conditions after their irradiation ( sup 1 sup 3 sup 7 Cs source). In the optical transmission measurements along with traditional techniques a method 'in situ' was used, which provided the measurements in fixed points of the spectrum (380, 470 and 535 nm) directly in the process of the irradiation. X-ray phase and fluorescence analysis of condensation products of vapours over PbWO sub 4 melt has found PbWO sub 4 phase in their content as well as compounds rich in lead PbO, Pb sub 2 WO sub 5 with overall ratio Pb/W (3....

  17. Non-stoichiometry Defects and Radiation Hardness of Lead Tungstate Crystals PbWO4

    CERN Document Server

    Devitsin, E G; Kozlov, V A; Nefedov, L; Polyansky, E V; Potashov, S Yu; Terkulov, A R; Zadneprovski, B I

    2001-01-01

    It has been stated many times that the formation of radiation infringements in PbWO4 is to big extent stipulated by non-stoichiometry defects of the crystals, arising in the process of their growth and annealing. To refine the idea of characteristics of non-stoichiometry defects and their effect on the radiation hardness of PbWO4 the current study is aimed at the melt composition infringements during its evaporation and at optical transmission of crystals obtained in these conditions after their irradiation (137Cs source). In the optical transmission measurements along with traditional techniques a method "in situ" was used, which provided the measurements in fixed points of the spectrum (380, 470 and 535 nm) directly in the process of the irradiation. X-ray phase and fluorescence analysis of condensation products of vapours over PbWO4 melt has found PbWO4 phase in their content as well as compounds rich in lead, PbO, Pb2WO5, with overall ratio Pb/W = 3.2. Correspondingly the lack of lead and variations in th...

  18. Charge doping and large lattice expansion in oxygen-deficient heteroepitaxial WO3

    Science.gov (United States)

    Mattoni, Giordano; Filippetti, Alessio; Manca, Nicola; Zubko, Pavlo; Caviglia, Andrea D.

    2018-05-01

    Tungsten trioxide (WO3) is a versatile material with widespread applications ranging from electrochromics and optoelectronics to water splitting and catalysis of chemical reactions. For technological applications, thin films of WO3 are particularly appealing, taking advantage from a high surface-to-volume ratio and tunable physical properties. However, the growth of stoichiometric crystalline thin films is challenging because the deposition conditions are very sensitive to the formation of oxygen vacancies. In this paper, we show how background oxygen pressure during pulsed laser deposition can be used to tune the structural and electronic properties of WO3 thin films. By performing x-ray diffraction and low-temperature electrical transport measurements, we find changes in the WO3 lattice volume of up to 10% concomitantly with a resistivity drop of more than five orders of magnitude at room temperature as a function of increased oxygen deficiency. We use advanced ab initio calculations to describe in detail the properties of the oxygen vacancy defect states and their evolution in terms of excess charge concentration. Our results depict an intriguing scenario where structural, electronic, optical, and transport properties of WO3 single-crystal thin films can all be purposely tuned by controlling the oxygen vacancy formation during growth.

  19. Combustion synthesized hierarchically porous WO{sub 3} for selective acetone sensing

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Chengjun; Liu, Xu; Guan, Hongtao; Chen, Gang; Xiao, Xuechun [Department of Materials Science and Engineering, Yunnan University, 650091, Kunming (China); Djerdj, Igor [Ruđer Bošković Institute, Bijenička 54, 10000, Zagreb (Croatia); Wang, Yude, E-mail: ydwang@ynu.edu.cn [Department of Materials Science and Engineering, Yunnan University, 650091, Kunming (China); Yunnan Province Key Lab of Mico-Nano Materials and Technology, Yunnan University, 650091, Kunming (China)

    2016-12-01

    An easy, inexpensive combustion route was designed to synthesize hierarchically porous WO{sub 3}. The tungsten source was fresh peroxiotungstic acid by dissolving tungsten powder into hydrogen peroxide. To promote the combustion reaction, a combined fuel of both glycine and hydrazine hydrate was used. The microstructure was well-connected pores comprised of subunit nanoparticles. Upon exposing towards acetone gas, the porous WO{sub 3} based sensor exhibits high gas response, rapid response and recovery, and good selectivity in the range of 5–1000 ppm under working temperature of 300 °C. This excellent sensing performance was plausibly attributed to the porous morphology, which hence provides more active sites for the gas molecules' reaction. - Graphical abstract: Hierarchically porous WO{sub 3} synthesized by combustion process exhibits high gas response, rapid response and recovery, and excellent selectivity for acetone, making it to be promising candidates for practical detectors for acetone. - Highlights: • Hierarchically porous WO{sub 3} synthesized by combustion process. • Hierarchically porous WO{sub 3} exhibits high gas response and excellent selectivity for acetone. • The excellent sensing property was plausibly attributed to the porous morphology.

  20. Nest-like structures of Sr doped Bi2WO6: Synthesis and enhanced photocatalytic properties

    International Nuclear Information System (INIS)

    Liu Ying; Wang Weimin; Fu Zhengyi; Wang Hao; Wang Yucheng; Zhang Jinyong

    2011-01-01

    Highlights: → Bi 2 WO 6 with 3D nest-like structures was obtained without the presence of templates but after Sr-doping, which represents a marked improvement over previous reports. → The products showed enhanced photocatalytic properties over pure Bi 2 WO 6 . → Samples subsequently thermal treated at 500 deg. C show better photocatalytic activities. - Abstract: A series of Sr-doped Bi 2 WO 6 with three-dimensional (3D) nest-like structures were synthesized through simple hydrothermal route and characterized by XRD, FESEM, TEM, XPS, UV-vis DRS, etc. Morphology observation revealed that the as-synthesized Bi 2 WO 6 were self-assembled three-dimensional (3D) nest-like structures, which were constructed from nanoplates. UV-vis diffuse reflectance spectra indicated that the samples had absorption in both UV and visible light areas. Their photocatalytic activities were evaluated by photodegradation of rhodamine B (RhB) under UV and visible light irradiation (λ > 420 nm). The photocatalytic properties were enhanced after Sr doping. Samples subsequently thermal treated at 500 deg. C showed higher photocatalytic activities. The reasons for the differences in the photocatalytic activities of these nest-like Bi 2 WO 6 microstructures were further investigated.

  1. Oxygen partial pressure effects on the magnetron sputtered WO3 films

    International Nuclear Information System (INIS)

    Muğlu, G Merhan; Gür, E

    2016-01-01

    Electrochromism is changing color of a substance in response to the applied an external electric field and the phenomenon is reversible. WO 3 is very attractive material due to its electrochromic properties as well as it is also attractive for many different applications such as gas sensors, phosphorous screen, textile, glass industry. In this study, it is aimed to provide optimization of the optical and structural characteristics of WO 3 by changing the growth parameters mainly the oxygen partial pressure. The partial pressure of oxygen was changed with increments of 0.7 mTorr. For the analysis, X-ray Diffraction (XRD), absorption, Raman spectroscopy measurements were used. When O 2 gas increased, peaks belong to the WO 3 was observed in XRD patterns at the 2 theta angles of 23.0, 11.0, 23.5 and 28.5 angles corresponding to the (002), (020) and (220) planes, respectively. This shows that there is a significant effect of increasing O 2 partial pressure in the formation of WO 3 films. The bandgap energy of the WO 3 thin films are found to be around 3.0 eV. Raman measurements showed vibrational modes of W-O-W stretching and bending modes which shows small shifts depending on the partial pressures of the O 2 . Obtained results indicated that better crystal structure is obtained with higher O 2 gas partial pressure. (paper)

  2. Synthesis of chemically bonded BiOCl@Bi{sub 2}WO{sub 6} microspheres with exposed (0 2 0) Bi{sub 2}WO{sub 6} facets and their enhanced photocatalytic activities under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Yongchao [Qingdao Agricultural University, Qingdao 266109 (China); Chen, Zhiwei [School of Life Sciences, Shandong University of Technology, Zibo 255049 (China); Qu, Dan [Qingdao Agricultural University, Qingdao 266109 (China); Shi, Jinsheng, E-mail: jsshiqn@aliyun.com [Qingdao Agricultural University, Qingdao 266109 (China)

    2016-01-15

    Graphical abstract: - Highlights: • BiOCl@Bi{sub 2}WO{sub 6} composites were prepared via a controlled anion exchange method. • The shell of composites was composed of Bi{sub 2}WO{sub 6} sheets with exposed (0 2 0) facets. • The BiOCl@Bi{sub 2}WO{sub 6} composites showed efficient photocatalytic activity. • A possible photocatalytic degradation mechanism is proposed. - Abstract: Bi{sub 2}WO{sub 6} photocatalysts has been extensively studied for its photocatalytic activity. However, few works have been conducted on hierarchical Bi{sub 2}WO{sub 6} composite photocatalysts with specifically exposed facets. In this work, we report a facile method to synthesize BiOCl@Bi{sub 2}WO{sub 6} hierarchical composite microspheres. Bi{sub 2}WO{sub 6} nanosheets with specifically exposed (0 2 0) facet were directly formed on the surface of BiOCl precursor microspheres via a controlled anion exchange route between BiOCl and Na{sub 2}WO{sub 4}. The visible-light photocatalytic activity of the BiOCl@Bi{sub 2}WO{sub 6} heterojunction with exposed (0 2 0) facets (denoted as BiOCl@Bi{sub 2}WO{sub 6}) was investigated by degradation of Rhodamine B (RhB) and ciprofloxacin (CIP) aqueous solution under visible light irradiation. The experimental results indicated that the BiOCl@Bi{sub 2}WO{sub 6} composite microsphere with intimate interfacial contacts exhibited improved efficiency for RhB photodegradation in comparison with pure BiOCl and Bi{sub 2}WO{sub 6}. The BiOCl@Bi{sub 2}WO{sub 6} composite microsphere also shows high photocatalytic activity for degradation of CIP under visible light irradiation. The enhanced photocatalytic performance of BiOCl@Bi{sub 2}WO{sub 6}-020 hierarchical microspheres can be ascribed to the improved visible light harvesting ability, high charge separation and transfer. This work will make significant contributions toward the exploration of novel heterostructures with high potential in photocatalytic applications.

  3. Exploration on anion ordering, optical properties and electronic structure in K3WO3F3 elpasolite

    International Nuclear Information System (INIS)

    Atuchin, V.V.; Isaenko, L.I.; Kesler, V.G.; Lin, Z.S.; Molokeev, M.S.; Yelisseyev, A.P.; Zhurkov, S.A.

    2012-01-01

    Room-temperature modification of potassium oxyfluorotungstate, G2-K 3 WO 3 F 3 , has been prepared by low-temperature chemical route and single crystal growth. Wide optical transparency range of 0.3–9.4 μm and forbidden band gap E g =4.32 eV have been obtained for G2-K 3 WO 3 F 3 crystal. Meanwhile, its electronic structure has been calculated with the first-principles calculations. The good agreement between the theorectical and experimental results have been achieved. Furthermore, G2-K 3 WO 3 F 3 is predicted to possess the relatively large nonlinear optical coefficients. - Graphical abstract: Using the cm-size K 3 WO 3 F 3 crystal (left upper), the transmission spectrum (right upper) and XPS valence electronic states (left lower) were measured, agreed with the ab initio results (right lower). Highlights: ► The cm-size G2-K 3 WO 3 F 3 single crystals are obtained. ► Optical absorption edge and transmission range are defined for G2-K 3 WO 3 F 3 crystal. ► Crystal structures of all known K 3 WO 3 F 3 polymorph modifications are determined. ► Experimental electronic structure is consistent with the first-principles result. ► G2-K 3 WO 3 F 3 is predicted as a crystal with large NLO coefficients.

  4. Structural properties of WO{sub 3} dependent of the annealing temperature deposited by hot-filament metal oxide deposition

    Energy Technology Data Exchange (ETDEWEB)

    Flores M, J. E. [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias de la Electronica, Av. San Claudio y 18 Sur, Ciudad Universitaria, Col. Jardines de San Manuel, 72570 Puebla (Mexico); Diaz R, J. [IPN, Centro de Investigacion en Biotecnologia Aplicada, Ex-Hacienda de San Molino Km 1.5 Tepetitla, 90700 Tlaxcala (Mexico); Balderas L, J. A., E-mail: eflores@ece.buap.mx [IPN, Unidad Profesional Interdisciplinaria de Biotecnologia, Av. Acueducto s/n, Col. Barrio la Laguna, 07340 Mexico D. F. (Mexico)

    2012-07-01

    In this work presents a study of the effect of the annealing temperature on structural and optical properties of WO{sub 3} that has been grown by hot-filament metal oxide deposition. The chemical stoichiometry was determined by X-ray photoelectron spectroscopy. By X-ray diffraction obtained that the as-deposited WO{sub 3} films present mainly monoclinic crystalline phase. WO{sub 3} optical band gap energy can be varied from 2.92 to 3.15 eV obtained by transmittance measurements by annealing WO{sub 3} from 100 to 500 C. The Raman spectrum of the as-deposited WO{sub 3} film shows four intense peaks that are typical Raman peaks of crystalline WO{sub 3} (m-phase) that corresponds to the stretching vibrations of the bridging oxygen that are assigned to W-O stretching ({upsilon}) and W-O bending ({delta}) modes, respectively, which enhanced and increased their intensity with the annealing temperature. (Author)

  5. Comparative studies of monoclinic and orthorhombic WO3 films used for hydrogen sensor fabrication on SiC crystal

    International Nuclear Information System (INIS)

    Zuev, V V; Romanov, R I; Fominski, V Y; Grigoriev, S N; Volosova, M A; Demin, M V

    2016-01-01

    Amorphous WO x films were prepared on the SiC crystal by using two different methods, namely, reactive pulsed laser deposition (RPLD) and reactive deposition by ion sputtering (RDIS). After deposition, the WO x films were annealed in an air. The RISD film possessed a m-WO 3 structure and consisted of closely packed microcrystals. Localized swelling of the films and micro-hills growth did not destroy dense crystal packing. RPLD film had layered β-WO 3 structure with relatively smooth surface. Smoothness of the films were destroyed by localized swelling and the micro-openings formation was observed. Comparative study of m-WO 3 /SiC, Pt/m-WO 3 /SiC, and P-WO 3 /SiC samples shows that structural characteristics of the WO 3 films strongly influence on the voltage/current response as well as on the rate of current growth during H 2 detection at elevated temperatures. (paper)

  6. Study of phase equilibria and glass formation in the CaO-WO3-P2O5 system

    International Nuclear Information System (INIS)

    Bielis, I.Ya.

    1980-01-01

    The method of quenching has been used to investigate the liquidus surface of a portion of the CaO-WO 3 -P 2 O 5 system limited by the Ca(PO 3 ) 2 -W 2 O 3 (PO 4 ) 2 and CaWO 4 -Ca 2 P 2 O 7 cross-sections. The primary crystallization fields on the compounds: WO 3 , W 2 O 3 (PO 4 ) 2 , CaWO 4 , Ca 2 P 7 O 7 , Ca(PO 3 ) 2 are separated. The liquidus surface isotherms at 900, 1000, 1100 and 1200 deg C have been plotted on the concentration triangle plane. It has been found that the cross-sections of W 2 O 3 (PO 4 ) 2 -Ca(PO 3 ) 2 , WO 3 -Ca(PO 3 ) 2 , WO 3 -Ca 2 P 2 O 7 and CaWO 4 -Ca 2 P 2 O 7 are eutectic-type quasi-binary systems. The position of the glass transition region in the CaO-WO 3 -P 2 O 5 system has been determined for the treatment temperatures of 1100, 1200 and 1300 deg C and a correlation between the configuration of the glass transition region and the phase diagram of the system has been demonstrated [ru

  7. Physical properties characterization of WO{sub 3} films grown by hot-filament metal oxide deposition

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Reyes, J., E-mail: jdiazr2001@yahoo.com [Centro de Investigacion en Biotecnologia Aplicada del Instituto Politecnico Nacional, Ex-Hacienda de San Juan Molino, Km. 1.5, Tepetitla, Tlaxcala, 90700 (Mexico); Delgado-Macuil, R.J. [Centro de Investigacion en Biotecnologia Aplicada del Instituto Politecnico Nacional, Ex-Hacienda de San Juan Molino, Km. 1.5, Tepetitla, Tlaxcala, 90700 (Mexico); Dorantes-Garcia, V. [Preparatoria ' Simon Bolivar' de la Benemerita Universidad Autonoma de Puebla, 4 Oriente 408, Col. Centro, Atlixco, Puebla, C. P. 74200 (Mexico); Perez-Benitez, A. [Facultad de Ciencias Quimicas de la Benemerita Universidad Autonoma Puebla, 14 Sur y Av. San Claudio, Col. San Manuel, Puebla, Puebla, C. P. 72570 (Mexico); Balderas-Lopez, J.A. [Unidad Profesional Interdisciplinaria de Biotecnologia del Instituto Politecnico Nacional, Avenida Acueducto S/N, Col. Barrio la Laguna, Ticoman, Del. Gustavo A. Madero, Mexico, D.F. 07340 (Mexico); Ariza-Ortega, J.A. [Centro de Investigacion en Biotecnologia Aplicada del Instituto Politecnico Nacional, Ex-Hacienda de San Juan Molino, Km. 1.5, Tepetitla, Tlaxcala, 90700 (Mexico)

    2010-10-25

    WO{sub 3} is grown by hot-filament metal oxide deposition (HFMOD) technique under atmospheric pressure and an oxygen atmosphere. By X-ray diffraction obtains that WO{sub 3} presents mainly monoclinic crystalline phase. The chemical stoichiometry is obtained by X-ray Photoelectron Spectroscopy (XPS). The IR spectrum of the as-grown WO{sub 3} presents broad peaks in the range of 1100 to 3600 cm{sup -1}. A broad band in the 2200 to 3600 cm{sup -1} region and the peaks sited at 1645 and 1432 cm{sup -1} are well resolved, which are originated from moisture and are assigned to {nu}(OH) and {delta}(OH) modes of adsorbed water and the corresponding tungsten oxide vibrations are in infrared region from 400 to 1453 cm{sup -1} and around 3492 cm{sup -1}, which correspond to tungsten-oxygen (W-O) stretching, bending and lattice modes. The Raman spectrum shows intense peaks at 801, 710, 262 and 61 cm{sup -1} that are typical Raman peaks of crystalline WO{sub 3} (m-phase) that correspond to stretching vibrations of the bridging oxygen, which are assigned to W-O stretching ({nu}) and W-O bending ({delta}) modes, respectively. By transmittance measurements obtains that the WO{sub 3} band gap can be varied from 2.92 to 3.13 eV in the investigated annealing temperature range.

  8. Rare-earth-ion doped KY(WO4)2 optical waveguides grown by liquid-phase epitaxy

    NARCIS (Netherlands)

    Romanyuk, Y.E.; Apostolopoulos, V.; Utke, U.; Pollnau, Markus

    High-quality KY(WO4)2 thin layers doped with rare-earth-ions were grown using liquid-phase epitaxy. A low-temperature mixture of chlorides was used as the flux and undoped KY(WO4)2 crystals as substrates. The crystalline layers possessed thicknesses up to 10 µm. Passive and active planar waveguiding

  9. Electronic and optical properties of nanocrystalline WO3 thin films studied by optical spectroscopy and density functional calculations

    International Nuclear Information System (INIS)

    Johansson, Malin B; Niklasson, Gunnar A; Österlund, Lars; Baldissera, Gustavo; Persson, Clas; Valyukh, Iryna; Arwin, Hans

    2013-01-01

    The optical and electronic properties of nanocrystalline WO 3 thin films prepared by reactive dc magnetron sputtering at different total pressures (P tot ) were studied by optical spectroscopy and density functional theory (DFT) calculations. Monoclinic films prepared at low P tot show absorption in the near infrared due to polarons, which is attributed to a strained film structure. Analysis of the optical data yields band-gap energies E g ≈ 3.1 eV, which increase with increasing P tot by 0.1 eV, and correlate with the structural modifications of the films. The electronic structures of triclinic δ-WO 3 , and monoclinic γ- and ε-WO 3 were calculated using the Green function with screened Coulomb interaction (GW approach), and the local density approximation. The δ-WO 3 and γ-WO 3 phases are found to have very similar electronic properties, with weak dispersion of the valence and conduction bands, consistent with a direct band-gap. Analysis of the joint density of states shows that the optical absorption around the band edge is composed of contributions from forbidden transitions (>3 eV) and allowed transitions (>3.8 eV). The calculations show that E g in ε-WO 3 is higher than in the δ-WO 3 and γ-WO 3 phases, which provides an explanation for the P tot dependence of the optical data. (paper)

  10. Electronic and optical properties of nanocrystalline WO3 thin films studied by optical spectroscopy and density functional calculations

    Science.gov (United States)

    Johansson, Malin B.; Baldissera, Gustavo; Valyukh, Iryna; Persson, Clas; Arwin, Hans; Niklasson, Gunnar A.; Österlund, Lars

    2013-05-01

    The optical and electronic properties of nanocrystalline WO3 thin films prepared by reactive dc magnetron sputtering at different total pressures (Ptot) were studied by optical spectroscopy and density functional theory (DFT) calculations. Monoclinic films prepared at low Ptot show absorption in the near infrared due to polarons, which is attributed to a strained film structure. Analysis of the optical data yields band-gap energies Eg ≈ 3.1 eV, which increase with increasing Ptot by 0.1 eV, and correlate with the structural modifications of the films. The electronic structures of triclinic δ-WO3, and monoclinic γ- and ε-WO3 were calculated using the Green function with screened Coulomb interaction (GW approach), and the local density approximation. The δ-WO3 and γ-WO3 phases are found to have very similar electronic properties, with weak dispersion of the valence and conduction bands, consistent with a direct band-gap. Analysis of the joint density of states shows that the optical absorption around the band edge is composed of contributions from forbidden transitions (>3 eV) and allowed transitions (>3.8 eV). The calculations show that Eg in ε-WO3 is higher than in the δ-WO3 and γ-WO3 phases, which provides an explanation for the Ptot dependence of the optical data.

  11. Red photoluminescent property and modification of WO3:Eu3+ inverse opal for blue light converted LEDs

    Science.gov (United States)

    Ruan, Jiufeng; Yang, Zhengwen; Huang, Anjun; Chai, Zhuangzhuang; Qiu, Jianbei; Song, Zhiguo

    2018-01-01

    Blue light converted light-emitting diodes is of great significance as a candidate for next generation lighting. In this work, the WO3:Eu3+ inverse opal photonic crystals were prepared and their luminescence properties were studied. The results demonstrated that the main excitation peak of WO3:Eu3+ inverse opals were located at 465 nm. The red luminescence peak at the 613 nm was observed in the WO3:Eu3+ inverse opal upon 465 nm excitation, exhibiting better red color purity. The influence of photonic band gap on the photoluminescence of WO3:Eu3+ inverse opal was obtained. When the red luminescence peak is in the regions of the photonic band gap and the edge of the band-gap, the red luminescence suppression and enhancement was observed respectively. The WO3:Eu3+ inverse opals may be a promising candidate for the blue light converted LEDs.

  12. Ultrasensitive ppb-level NO2 gas sensor based on WO3 hollow nanosphers doped with Fe

    Science.gov (United States)

    Zhang, Ziyue; haq, Mahmood; Wen, Zhen; Ye, Zhizhen; Zhu, Liping

    2018-03-01

    WO3 mesoporous hollow nanospheres doped with Fe synthesized by a facile method have mesoporous hollow nanospherical like morphology, small grain size (10 nm), high crystalline quality and ultrahigh surface area (165 m2/g). XRD spectra and Raman spectra indicate the Fe doping leading to the smaller cell parameters as compared to pure WO3, and the slight distortion in the crystal lattice produces a number of defects, making it a better candidate for gas sensing. XPS analysis shows that Fe-doped WO3 mesoporous hollow nanospheres have more oxygen vacancies than pure WO3, which is beneficial to the adsorption of oxygen and NO2 and its surface reaction. The gas sensor based on Fe-WO3 exhibited excellent low ppb-level (10 ppb) NO2 detecting performance and outstanding selectivity.

  13. Controllable Fabrication of Ordered Mesoporous Bi2WO6 and Its High Photocatalytic Activity under Visible Light

    Directory of Open Access Journals (Sweden)

    Xueming Dang

    2014-01-01

    Full Text Available Ordered mesoporous Bi2WO6 was fabricated by nanocasting technique using SBA-15 as the template. The effect of the dosage of SBA-15 on the formation of the ordered structure and the photocatalytic ability of mesoporous Bi2WO6 was discussed. It was confirmed that the ordered mesoporous structure was obtained as the dosage of SBA-15 was 0.3 g. It was found that, compared to Bi2WO6, the RhB degradation rate with ordered mesoporous Bi2WO6 was enhanced under visible light (λ>400 nm by the photocatalytic measurements. The enhanced photocatalytic performance of ordered mesoporous Bi2WO6 was attributed to its particular ordered mesoporous structure which could increase the light-harvesting efficiency, reduce the recombination of the photogenerated charge carriers, and promote the surface reaction.

  14. Synthesis and characterization of large WO{sub 3} sheets synthesized by resistive heating method

    Energy Technology Data Exchange (ETDEWEB)

    Filippo, Emanuela, E-mail: emanuela.filippo@unisalento.it [Department of Engineering for Innovation, University of Salento, Monteroni Street, Lecce I-73100 Italy (Italy); Tepore, Marco [Department of Engineering for Innovation, University of Salento, Monteroni Street, Lecce I-73100 Italy (Italy); Baldassarre, Francesca [Department of Cultural Heritage, University of Salento, Lecce I-73100 Italy (Italy); Quarta, Gianluca; Calcagnile, Lucio [Department of Engineering for Innovation, University of Salento, Monteroni Street, Lecce I-73100 Italy (Italy); Guascito, Maria Rachele [DiSTeBA, University of Salento, Lecce I-73100 Italy (Italy); Tepore, Antonio [Department of Cultural Heritage, University of Salento, Lecce I-73100 Italy (Italy)

    2015-09-01

    A simple, low-cost method is presented to grow tungsten oxide large sheets simply by resistively heating a pure tungsten filament under air/water vapor flow. The obtained structures were studied using scanning and transmission electron microscopy, selected area diffraction, X Ray diffraction, Raman and X-ray photoelectron spectroscopy, photoluminescence and zeta potential measurements. SEM observations revealed that sheets formed by broadening of the wires/belts over longer growth period. Photoluminescence measurements showed that tungsten oxide sheets had an intense visible emission band. - Highlights: • WO{sub 3} large sheets were prepared by resistively heating a W filament. • WO{sub 3} sheets were carefully characterized. • Formation mechanism of sheets was studied. • WO{sub 3} sheets had an intense visible emission band at 462 nm.

  15. Radiation-induced color centers in La-doped PbWO sub 4 crystals

    CERN Document Server

    Deng, Q; Zhu, R Y

    1999-01-01

    This report presents the result of a study on radiation-induced color center densities in La-doped lead tungstate (PbWO sub 4) crystals. The creation and annihilation constants of radiation-induced color centers were determined by using transmittance data measured for a PbWO sub 4 sample before and during sup 6 sup 0 Co gamma-ray irradiation at a dose rate of 15 rad/h. Following a model of color center kinetics, these constants were used to calculate color center densities under irradiations at 100 rad/h. The result was found to be in good agreement with experimental data, indicating that the behaviour of PbWO sub 4 crystals under irradiation can be predicted according to this model.

  16. Surface Functionalization of WO3 Thin Films with (3-Aminopropyl)triethoxysilane and Succinic Anhydride

    Science.gov (United States)

    Ta, Thi Kieu Hanh; Tran, Thi Nhu Hoa; Tran, Quang Minh Nhat; Pham, Duy Phong; Pham, Kim Ngoc; Cao, Thi Thanh; Kim, Yong Soo; Tran, Dai Lam; Ju, Heongkyu; Phan, Bach Thang

    2017-06-01

    We report effects of oxygen plasma treatment on the surface functionalization of WO3 thin films with (3-aminopropyl)triethoxysilane (APTES) and succinic anhydride (SA). X-ray diffraction and x-ray photoelectron spectroscopy results indicate the existence of the WO3 phase. Fourier transform infrared spectroscopy measurement shows clear bands at 1040 cm-1 (Si-O-Si), 1556 cm-1 (N-H), 1655 cm-1 (C=O), 2937 cm-1 (C-H) and 3298 cm-1 (N-H), confirming the surface functionalization efficiency enhanced by prior treatment of oxygen plasma. It thus follows that the prior oxygen plasma treatment activates hydroxylation with more -OH groups on the WO3 surface, which can pave a highly efficient way to the surface functionalization by APTES and SA.

  17. Scintillation properties of pure and Ca-doped ZnWO4 crystals

    International Nuclear Information System (INIS)

    Danevich, F.A.; Shkulkova, O.G.; Henry, S.; Kraus, H.; McGowan, R.; Mikhailik, V.B.; Telfer, J.

    2008-01-01

    Following the investigations of the structure and scintillation properties of Ca-doped zinc tungstate powder [phys. stat. sol. (a) 204, 730 (2007)] a single-crystal of ZnWO 4 -Ca (0.5 mol%) was grown and characterised. The relative light output, energy resolution and decay characteristics were measured for pure and Ca-doped ZnWO 4 scintillators. An increase in the light yield of ∝40% compared with the undoped crystal, and an energy resolution 9.6% ( 137 Cs) were obtained for Ca-doped ZnWO 4 . The observed improvement is attributed to the reduction of self-absorption (bleaching) of the crystal. The cause of bleaching as well as the possible contribution of scattering is discussed. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Mechanism Of Long Term Change In Electrochrcmism Of LixWO3 Films

    Science.gov (United States)

    Nagai, Junichi; Kamimori, Tadatoshi; Mizuhashi, Mamoru

    1984-11-01

    The degradation mechanism of gradual decrease of the contrast between colored and bleached states of Lix'. WO3 films with switching cycles was investigated. We made electro-chemical and quantitative chemical analyses to clarify this phenomenon. It was found that the decrease in contrast was mostly attributed to the parallel cathodic shift of emf(x), passibly caused by ion exchange reaction expressed by: WOH + Li+ WOLi + H. Fully ion-exchanged WO3 films showed no appreciable change in spite of the presence of a large amount of Li in them. These films were capable of accepting as much Li as the fresh films did on coloration and reached to the same optical densities. It is concluded that there are two kinds of active sites available for accepting lithium ions in the WO3 structure, one for ion exchange and the other for coloration.

  19. Giant Persistent Photoconductivity of the WO3 Nanowires in Vacuum Condition

    Directory of Open Access Journals (Sweden)

    Huang Kai

    2011-01-01

    Full Text Available Abstract A giant persistent photoconductivity (PPC phenomenon has been observed in vacuum condition based on a single WO3 nanowire and presents some interesting results in the experiments. With the decay time lasting for 1 × 104 s, no obvious current change can be found in vacuum, and a decreasing current can be only observed in air condition. When the WO3 nanowires were coated with 200 nm SiO2 layer, the photoresponse almost disappeared. And the high bias and high electric field effect could not reduce the current in vacuum condition. These results show that the photoconductivity of WO3 nanowires is mainly related to the oxygen adsorption and desorption, and the semiconductor photoconductivity properties are very weak. The giant PPC effect in vacuum condition was caused by the absence of oxygen molecular. And the thermal effect combining with oxygen re-adsorption can reduce the intensity of PPC.

  20. Gasochromic performance of WO3-nanorod thin films fabricated with an ArF excimer laser

    International Nuclear Information System (INIS)

    Yaacob, M. H.; Ou, J. Z.; Wlodarski, W.; Kim, C. S.; Lee, J. Y.; Kim, Y. H.; Oh, C. M.; Dhakal, K. P.; Kim, J. Y.; Kang, J. H.

    2012-01-01

    Thin films with tungsten trioxide (WO 3 ) nanorods were fabricated by using an ArF pulsed laser deposition system. Because the ArF excimer laser operates at a very short wavelength of 193 nm, short enough to expect strong absorption of the photons in the semiconductor oxide targets, and because the clusters incoming to the substrates have high momentum, we could build thin films with good surface morphology. Highly homogeneous arrays of nanorods with sizes mostly in the range of 30 - 40 nm were observed. The absorbance response towards hydrogen (H 2 ) gas was investigated for a WO 3 film coated with 25-A-thick palladium (Pd). The Pd/WO 3 -nanorod thin films exhibited excellent gasochromic response when measured in the visible-NIR range (400 - 1000 nm). As low as 0.06% H 2 concentration was clearly sensed. A significant reversible absorbance change and fast recovery ( 2 at different concentrations.

  1. Understanding the Potential of WO3 Based Sensors for Breath Analysis

    Science.gov (United States)

    Staerz, Anna; Weimar, Udo; Barsan, Nicolae

    2016-01-01

    Tungsten trioxide is the second most commonly used semiconducting metal oxide in gas sensors. Semiconducting metal oxide (SMOX)-based sensors are small, robust, inexpensive and sensitive, making them highly attractive for handheld portable medical diagnostic detectors. WO3 is reported to show high sensor responses to several biomarkers found in breath, e.g., acetone, ammonia, carbon monoxide, hydrogen sulfide, toluene, and nitric oxide. Modern material science allows WO3 samples to be tailored to address certain sensing needs. Utilizing recent advances in breath sampling it will be possible in the future to test WO3-based sensors in application conditions and to compare the sensing results to those obtained using more expensive analytical methods. PMID:27801881

  2. Bibliometric analysis of publications on wine tourism in the databases Scopus and WoS

    Directory of Open Access Journals (Sweden)

    Amador Durán Sánchez

    2017-01-01

    Full Text Available The aim of this study was to show the current state of scientific research regarding wine tourism, by comparing the platforms of scientific information WoS and Scopus and applying quantitative methods. For this purpose, a bibliometric study of the publications indexed in WoS and Scopus was conducted, analyzing the correlation between increases, coverage, overlap, dispersion and concentration of documents. During the search process, a set of 238 articles and 122 different journals were obtained. Based on the results of the comparative study, we conclude that WoS and Scopus databases differ in scope, data volume and coverage policies with a high degree of unique sources and articles, resulting both of them complementary and not mutually exclusive. Scopus covers the area of wine tourism better, by including a greater number of journals, papers and signatures.

  3. Conductive surface modification of cauliflower-like WO{sub 3} and its electrochemical properties for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Sukeun, E-mail: skyoon@kongju.ac.kr [Division of Advanced Materials Engineering, Kongju National University, Chungnam 330-717 (Korea, Republic of); Woo, Sang-Gil [Advanced Batteries Research Center, Korea Electronics Technology Institute, Gyeonggi 463-816 (Korea, Republic of); Jung, Kyu-Nam [Energy Efficiency and Materials Research Division, Korea Institute of Energy Research, Daejeon 305-343 (Korea, Republic of); Song, Huesup, E-mail: hssong@kongju.ac.kr [Division of Advanced Materials Engineering, Kongju National University, Chungnam 330-717 (Korea, Republic of)

    2014-11-15

    Highlights: • Synthesis of cauliflower-like carbon-decorated WO{sub 3}. • Superior cyclability and rate capability for cauliflower-like carbon-decorated WO{sub 3}. • Electrochemical reaction behavior of cauliflower-like carbon-decorated WO{sub 3} with lithium. • In-situ XRD analysis during the first discharge–charge shows a complex reaction of intercalation and conversion of WO{sub 3}. - Abstract: Cauliflower-like WO{sub 3} was synthesized by a hydrothermal reaction without a surfactant, followed by firing, and was investigated as an anode material for lithium-ion battery applications. The scanning electron microscope (SEM) and transmission electron microscope (TEM) characterization indicated that WO{sub 3} nanorods had an aggregation framework and built a cauliflower morphology. With the objective of understanding the charge–discharge process within a voltage range of 0–3 V vs. Li{sup +}/Li, in situ X-ray diffraction was used and a complex reaction of intercalation and conversion of WO{sub 3} was revealed for the first time. The cauliflower-like WO{sub 3} after being decorated with carbon provides a high gravimetric capacity of >635 mA h/g (Li{sub 5.5}WO{sub 3}) with good cycling and a high rate capability when used as an anode in lithium-ion batteries. Based on our studies, we attribute the high electrochemical performance to the nanoscopic WO{sub 3} particles and a conductive carbon layer, which makes them a potential candidate for lithium-ion batteries.

  4. Electron microscopy analyses and electrical properties of the layered Bi2WO6 phase

    International Nuclear Information System (INIS)

    Taoufyq, A.; Ait Ahsaine, H.; Patout, L.; Benlhachemi, A.; Ezahri, M.

    2013-01-01

    The bismuth tungstate Bi 2 WO 6 was synthesized using a classical coprecipitation method followed by a calcination process at different temperatures. The samples were characterized by X-ray diffraction, simultaneous thermogravimetry and differential thermal analysis (TGA/DTA), scanning and transmission electron microscopy (SEM, TEM) analyses. The Rietveld analysis and electron diffraction clearly confirmed the Pca2 1 non centrosymmetric space group previously proposed for this phase. The layers Bi 2 O 2 2+ and WO 4 2− have been directly evidenced from the HRTEM images. The electrical properties of Bi 2 WO 6 compacted pellets systems were determined from electrical impedance spectrometry (EIS) and direct current (DC) analyses, under air and argon, between 350 and 700 °C. The direct current analyses showed that the conduction observed from EIS analyses was mainly ionic in this temperature range, with a small electronic contribution. Electrical change above the transition temperature of 660 °C is observed under air and argon atmospheres. The strong conductivity increase observed under argon is interpreted in terms of formation of additional oxygen vacancies coupled with electron conduction. - Graphical abstract: High resolution transmission electron microscopy: inverse fast Fourier transform giving the layered structure of the Bi 2 WO 6 phase, with a representation of the cell dimensions (b and c vectors). The Bi 2 O 2 2+ and WO 4 2− sandwiches are visible in the IFFT image. - Highlights: • Using transmission electron microscopy, we visualize the layered structure of Bi 2 WO 6 . • Electrical analyses under argon gas show some increase in conductivity. • The phase transition at 660 °C is evidenced from electrical modification

  5. Polarized spectroscopic properties of Nd3+-doped KGd(WO4)2 single crystal

    International Nuclear Information System (INIS)

    Chen Yujin; Lin Yanfu; Gong Xinghong; Tan Qiguang; Zhuang Jian; Luo Zundu; Huang Yidong

    2007-01-01

    The polarized absorption spectra, infrared fluorescence spectra, upconversion visible fluorescence spectra, and fluorescence decay curve of orientated Nd 3+ :KGd(WO 4 ) 2 crystal were measured at room-temperature. Some important spectroscopic parameters were investigated in detail in the framework of the Judd-Ofelt theory and the Fuchtbauer-Ladenburg formula. The effect of the crystal structure on the spectroscopic properties of the Nd 3+ ions was analyzed. The relation among the spectroscopic parameters and the laser performances of the Nd 3+ :KGd(WO 4 ) 2 crystal was discussed

  6. Synthesis, formation mechanism and sensing properties of WO3 hydrate nanowire netted-spheres

    International Nuclear Information System (INIS)

    Yan, Aihua; Xie, Changsheng; Zeng, Dawen; Cai, Shuizhou; Hu, Mulin

    2010-01-01

    Tungsten oxide hydrate nanowire netted-spheres were successfully synthesized in the glycol solution using a facile solvothermal approach. The nanowires with uniform diameter of 4-6 nm are actually a kind of tungsten oxide hydrate/surfactant hybrid materials. The influence of surfactant, solvent, time and temperature on tailoring morphology was investigated in detail. The possible formation process of WO 3 hydrate nanowire netted-sphere was proposed. Sensing properties of such WO 3 hydrate sensor show that the desirable sensing characteristics towards 100 ppm ammonia gas at 320 o C were obtained, such as rapid response (18.3 s), high sensitivity, good reproducibility and stability.

  7. Advanced nanostructured photocatalysts based on reduced graphene oxide-flower-like Bi_2WO_6 composites for an augmented simulated solar photoactivity activity

    International Nuclear Information System (INIS)

    Li, Yukun; Chen, Lin; Wang, Yue; Zhu, Liang

    2016-01-01

    Highlights: • A simple route was proposed to prepare flower-like Bi_2WO_6 and RGO/Bi_2WO_6. • Cipro HCl was degraded firstly by RGO/Bi_2WO_6 under the visible-light. • 2% RGO/Bi_2WO_6 exhibited the best removal efficiency. - Abstract: A simple hydrothermal process was proposed to prepare the flower-like Bi_2WO_6 architectures, and the as-synthesized Bi_2WO_6 photocatalysts were further processed with the prepared graphene oxide (GO) to form novel reduced graphene oxide (RGO)/Bi_2WO_6 composites. The nano-materials were characterized with the help of XRD, XPS, SEM, FTIR, UV-DRS, PL techniques to investigate their morphological, physical, optical, and photochemical properties. Photocatalytic performances of the pure flower-like Bi_2WO_6 architectures and RGO/Bi_2WO_6 composites were compared and evaluated through the degradation of ciprofloxacin hydrochloride (Cipro HCl) wastewater under the simulated visible light. It was found that the RGO/Bi_2WO_6 composites displayed enhanced visible light-driven photocatalytic activities. It might be that the RGO loading not only effectively suppressed the electron–hole recombination, but also increased the light absorption ability. The effects of operating condition involved in the photocatalytic process were further examined, and the cycle-stability experiment demonstrated that as-obtained 2% RGO/Bi_2WO_6 photocatalysts had good photocatalytic repeatability.

  8. Preparation of Ba1-xSrxWO4 and Ba1-xCaxWO4 films on tungsten plate by mechanically assisted solution reaction at room temperature

    International Nuclear Information System (INIS)

    Rangappa, Dinesh; Fujiwara, Takeshi; Watanabe, Tomoaki; Yoshimura, Masahiro

    2008-01-01

    Preparation of the alkaline earth tungstate films such as Ba 1-x Sr x WO 4 and Ba 1-x Ca x WO 4 on the tungsten substrate was studied with a simple solution process assisted with the ball rotation at room temperature. The solid solution formation and limitations, the effect of oxidizing agent H 2 O 2 and alkaline earth ions concentration on the dissolution of W substrate and the growth of Ba 1-x Sr x WO 4 and Ba 1-x Ca x WO 4 films were studied in detail. The ball rotation assistance plays a very important role to enhance the dissolution of the W substrate and mass transport of the reactant species such as alkaline earth ions and WO 4 2- ions onto the solid/solution interface region, where precipitation occurs. Therefore, the rate of film formation was accelerated by the ball rotation assistance to the reaction system. Ba-rich Ba 1-x Sr x WO 4 and Ba 1-x Ca x WO 4 films were formed without high energy or high temperature treatment

  9. Preparation of tungsten coatings on graphite by electro-deposition via Na{sub 2}WO{sub 4}–WO{sub 3} molten salt system

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Ning-bo [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Zhang, Ying-chun, E-mail: zycustb@163.com [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Jiang, Fan; Lang, Shao-ting [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Xia, Min [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Institute of Powder Metallurgy and Advanced Ceramics, Southwest Jiaotong University, 111, 1st Section, Northern 2nd Ring Road, Chengdu (China)

    2014-11-15

    Highlights: • Tungsten coatings on graphite were firstly obtained by electro-deposition method via Na{sub 2}WO{sub 4}–WO{sub 3} molten salt system. • Uniform and dense tungsten coatings could be easily prepared in each face of the sample, especially the complex components. • The obtained tungsten coatings are with high purity, ultra-low oxygen content (about 0.022 wt%). • Modulate pulse parameters can get tungsten coatings with different thickness and hardness. - Abstract: Tungsten coating on graphite substrate is one of the most promising candidate materials as the ITER plasma facing components. In this paper, tungsten coatings on graphite substrates were fabricated by electro-deposition from Na{sub 2}WO{sub 4}–WO{sub 3} molten salt system at 1173 K in atmosphere. Tungsten coatings with no impurities were successfully deposited on graphite substrates under various pulsed current densities in an hour. By increasing the current density from 60 mA cm{sup −2} to 120 mA cm{sup −2} an increase of the average size of tungsten grains, the thickness and the hardness of tungsten coatings occurs. The average size of tungsten grains can reach 7.13 μm, the thickness of tungsten coating was in the range of 28.8–51 μm, and the hardness of coating was higher than 400 HV. No cracks or voids were observed between tungsten coating and graphite substrate. The oxygen content of tungsten coating is about 0.022 wt%.

  10. Numerical model of the catchments of the oziąbel and wołczyński strumień rivers - Wołczyn municipality

    Science.gov (United States)

    Olichwer, Tomasz; Wcisło, Marek; Staśko, Stanisław; Buczyński, Sebastian; Modelska, Magdalena; Tarka, Robert

    2012-10-01

    The article presents a numerical model designed for determining groundwater dynamics and water balance of the catchments of the Oziąbel (Czarna Woda) river and the Wołczyński Strumień river in Wołczyn region. Hydrogeological mapping and modelling research covered the area of 238.9 km2. As a result of measurements performed in 2008-2009, flows were determined in major rivers and water table positions were measured at 26 points. In the major part of the area described, the water table, lying at the depth of 1.5-18.7 m, has unconfined character, and the aquifer is built of Neogene (Quaternary) sands and gravels. In the area under study, groundwaters are drawn from 6 wells with total withdrawal of 6133 m3/d. The numerical modelling was performed with the use of Visual Modflow 3.1.0 software. The area was partitioned by a discretization grid with a step size l = 250 m. The conceptual model of the hydrogeological system is based on hydrological data gathered over a period of one year, data from HYDRO bank database, cross-sections and maps. The boundaries of the modelled hydrogeological system were established on the watersheds of the Wołczyński Strumień river and the Oziąbel river, apart from the areas where they run together. The modelled area was extended (271.5 km2) around the Wołczyński Strumień river catchment to achieve a more effective mapping of the anthropogenic impact on its balance and the hydrodynamic system of the catchment area. The structure is characterised by the occurrence of one or rarely two aquifers separated by a pack of Quaternary clays. The investigation produced a detailed water balance and its components.

  11. Ag loaded WO{sub 3} nanoplates for efficient photocatalytic degradation of sulfanilamide and their bactericidal effect under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wenyu [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141 (Singapore); Liu, Jincheng, E-mail: JCLIU@ntu.edu.sg [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Current address: Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510009 (China); Yu, Shuyan; Zhou, Yan [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141 (Singapore); Yan, Xiaoli, E-mail: XLYAN@ntu.edu.sg [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Current address: Environmental and Water Technology Centre of Innovation, Ngee Ann Polytechnic, 535 Clementi Road, Singapore 599489 (Singapore)

    2016-11-15

    Highlights: • WO{sub 3}/Ag heterogeneous composites were fabricated with simply photo-reduction method. • Property changes due to Ag loading were systematically studied. • WO{sub 3}/Ag composites efficiently degraded sulfanilamide under visible light irradiation. • WO{sub 3}/Ag composites exhibited bactericidal effectS under visible light irradiation. - Abstract: Sulfonamides (SAs) are extensively used antibiotics and their residues in the water bodies propose potential threat to the public. In this study, degradation efficiency of sulfanilamide (SAM), which is the precursor of SAs, using WO{sub 3} nanoplates and their Ag heterogeneous as photocatalysts was investigated. WO{sub 3} nanoplates with uniform size were synthesized by a facile one step hydrothermal method. Different amount of Ag nanoparticles (Ag NPs) were loaded onto WO{sub 3} nanoplates using a photo-reduction method to generate WO{sub 3}/Ag composites. The physio-chemical properties of synthesized nanomaterials were systematically characterized. Photodegradation of SAM by WO{sub 3} and WO{sub 3}/Ag composites was conducted under visible light irradiation. The results show that WO{sub 3}/Ag composites performed much better than pure WO{sub 3} where the highest removal rate was 96.2% in 5 h. Ag as excellent antibacterial agent also endows certain antibacterial efficiency to WO{sub 3}, and 100% removal efficiency against Escherichia Coli and Bacillus subtilis could be achieved in 2 h under visible light irradiation for all three WO{sub 3}/Ag composites synthesized. The improved performance in terms of SAM degradation and antibacterial activity of WO{sub 3}/Ag can be attributed to the improved electron-hole pair separation rate where Ag NPs act as effective electron trapper during the photocatalytic process.

  12. Enhanced structural and optical properties of the polyaniline-calcium tungstate (PANI-CaWO4 nanocomposite for electronics applications

    Science.gov (United States)

    Sabu, N. Aloysius; Francis, Xavier; Anjaly, Jose; Sankararaman, S.; Varghese, Thomas

    2017-06-01

    In this article, we report the synthesis and characterization of polyaniline-calcium tungstate nanocomposite, a novel material for potential applications. The PANI-CaWO4 nanocomposite was prepared by in situ oxidative polymerization of aniline in the presence of CaWO4 nanoparticles dispersed in ethanol. Investigations using X-ray diffraction, Fourier-transformed infrared spectroscopy, UV-visible, photoluminescence and Raman spectroscopy confirmed the formation of the nanocomposite of PANI with CaWO4 nanoparticles. Scanning electron microscopy revealed almost uniform distribution of CaWO4 nanoparticles in the polyaniline matrix. These studies also confirmed electronic structure modification as a result of incorporating CaWO4 nanoparticles in PANI. Composite formation resulted in large decrease in the optical band gap and enhanced photoluminescence. The augmented structural, optical and photoluminescence properties of the PANI-CaWO4 nanocomposite can be used to explore potential applications in micro- and optoelectronics. This is the first report presenting synthesis and characterization of the PANI-CaWO4 nanocomposite.

  13. Incorporation of tantalum ions enhances the electrocatalytic activity of hexagonal WO3 nanowires for hydrogen evolution reaction

    International Nuclear Information System (INIS)

    Xie, Xiang; Mu, Wanjun; Li, Xingliang; Wei, Hongyuan; Jian, Yuan; Yu, Qianhong; Zhang, Rui; Lv, Kai; Tang, Hui; Luo, Shunzhong

    2014-01-01

    WO 3 has been identified as a promising candidate electrocatalyst for hydrogen evolution reaction (HER), because it can form a tungsten bronze (HxWO 3 ) which is highly electron and proton conducting. In this paper, we report that the electrocatalytic activity of WO 3 for HER can be enhanced by incorporation of tantalum ions (Ta 5+ ) into the lattice of WO 3 . The most active performance is achieved with the molar ratio of Ta/W being 0.01, which is two times more active than that of undoped WO 3 at an overpotential of -0.52 V. It is shown that incorporation of proper Ta 5+ into WO 3 can induce moderate defects and oxygen vacancies, as well as intercalate a higher amount of protons, which enhance the electron transfer and short the protons diffusion paths. These changes correlated positively with the enhanced catalytic HER activity. This study demonstrates, for the first time, that metal ions-doped WO 3 nanowires are promising electrocatalysts for HER

  14. Study of photocatalytic activities of Bi2WO6 nanoparticles synthesized by fast microwave-assisted method

    International Nuclear Information System (INIS)

    Phu, Nguyen Dang; Hoang, Luc Huy; Chen, Xiang-Bai; Kong, Meng-Hong; Wen, Hua-Chiang; Chou, Wu Ching

    2015-01-01

    We present a study of photocatalytic activities of Bi 2 WO 6 nanoparticles synthesized by fast microwave-assisted method. The photocatalytic activities of the nanoparticles were evaluated by the decolorization of methylene-blue under visible-light-irradiation. Our results show that the surface area of Bi 2 WO 6 nanoparticles plays a major role for improving photocatalytic activity, while visible-light absorption has only a weak effect on photocatalytic activity. This suggests efficient transportation of photo-generated electrons and holes to the oxidation active sites on the surface of nanoparticles, indicating Bi 2 WO 6 nanoparticles synthesized by fast microwave-assisted method are promising for achieving high photocatalytic activity under visible-light-irradiation. - Highlights: • The Bi 2 WO 6 nanoparticles were synthesized via fast microwave-assisted method. • The obtained Bi 2 WO 6 nanoparticles exhibited visible-light absorbance. • The surface area of Bi 2 WO 6 nanoparticles plays major role for improving photocatalytic activity. • The Bi 2 WO 6 nanoparticles are promising for achieving high photocatalytic activity under visible-light-irradiation

  15. A Facile Synthesis of Graphene-WO3 Nanowire Clusters with High Photocatalytic Activity for O2 Evolution

    Directory of Open Access Journals (Sweden)

    M.-J. Zhou

    2014-01-01

    Full Text Available In the present work, graphene-WO3 nanowire clusters were synthesized via a facile hydrothermal method. The obtained graphene-WO3 nanowire clusters were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, Fourier transform infrared spectroscopy (FT-IR, Raman spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy (DRS techniques. The photocatalytic oxygen (O2 evolution properties of the as-synthesized samples were investigated by measuring the amount of evolved O2 from water splitting. The graphene-WO3 nanowire clusters exhibited enhanced performance compared to pure WO3 nanowire clusters for O2 evolution. The amount of evolved O2 from water splitting after 8 h for the graphene-WO3 nanowire clusters is ca. 0.345 mmol/L, which is more than 1.9 times as much as that of the pure WO3 nanowire clusters (ca. 0.175 mmol/L. The high photocatalytic activity of the graphene-WO3 nanowire clusters was attributed to a high charge transfer rate in the presence of graphene.

  16. Photocatalytic activity of Bi{sub 2}WO{sub 6}/Bi{sub 2}S{sub 3} heterojunctions: the facilitation of exposed facets of Bi{sub 2}WO{sub 6} substrate

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Long [School of Chemistry and Chemical Engineering, Yulin University, Shaanxi Key Laboratory of Low Metamorphic Coal Clean Utilization, Yulin 71900 (China); School of Chemistry and Chemical Engineering, Yan’an University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan’an 716000 (China); Wang, Yufei [School of Chemistry and Chemical Engineering, Yulin University, Shaanxi Key Laboratory of Low Metamorphic Coal Clean Utilization, Yulin 71900 (China); Shen, Huidong; Zhang, Yu [School of Chemistry and Chemical Engineering, Yan’an University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan’an 716000 (China); Li, Jian [School of Chemistry and Chemical Engineering, Yulin University, Shaanxi Key Laboratory of Low Metamorphic Coal Clean Utilization, Yulin 71900 (China); Wang, Danjun, E-mail: yulyanlong@aliyun.com [School of Chemistry and Chemical Engineering, Yan’an University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan’an 716000 (China)

    2017-01-30

    Highlights: • Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6} hybrids with exposed (020) Bi{sub 2}WO{sub 6} facets have been synthesized. • X-ray photoelectron spectroscopy reveals that a small amount of Bi{sub 2}S{sub 3} was formed. • The enhanced photoactivity of hybrids is due to heterojunction and (020) facets. • A possible photocatalytic degradation mechanism is proposed. - Abstract: Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6} hybrid architectures with exposed (020) Bi{sub 2}WO{sub 6} facets have been synthesized via a controlled anion exchange approach. X-ray photoelectron spectroscopy (XPS) reveals that a small amount of Bi{sub 2}S{sub 3} was formed on the surface of Bi{sub 2}WO{sub 6} during the anion exchange process, thus leading to the transformation from the Bi{sub 2}WO{sub 6} to Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6}. A rhodamine B (RhB) aqueous solution was chosen as model organic pollutants to evaluate the photocatalytic activities of the Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6} catalysts. Under visible light irradiation, the Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6}-TAA displayed the excellent visible light photoactivities compared with pure Bi{sub 2}S{sub 3}, Bi{sub 2}WO{sub 6} and other composite photocatalysts. The efficient photocatalytic activity of the Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6}-TAA composite microspheres was ascribed to the constructed heterojunctions and the inner electric field caused by the exposed (020) Bi{sub 2}WO{sub 6} facets. Active species trapping experiments revealed that h{sup +} and O{sub 2}·{sup −} are the main active species in the photocatalytic process. Furthermore, the as-obtained photocatalysts showed good photocatalytic activity after four recycles. The results presented in this study provide a new concept for the rational design and development of highly efficient photocatalysts.

  17. NO{sub 2} gas sensing of flame-made Pt-loaded WO{sub 3} thick films

    Energy Technology Data Exchange (ETDEWEB)

    Samerjai, Thanittha [Nanoscience and Nanotechnology Program, Faculty of Graduate School, Chiang Mai University, Chiang Mai 50200 (Thailand); Tamaekong, Nittaya [Program in Materials Science, Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Liewhiran, Chaikarn [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wisitsoraat, Anurat [Nanoelectronics and MEMS Laboratory, National Electronics and Computer Technology Center, Klong Luang, Pathumthani 12120 (Thailand); Phanichphant, Sukon, E-mail: sphanichphant@yahoo.com [Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2014-06-01

    Unloaded WO{sub 3} and 0.25–1.0 wt% Pt-loaded WO{sub 3} nanoparticles for NO{sub 2} gas detection were synthesized by flame spray pyrolysis (FSP) and characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The BET surface area (SSA{sub BET}) of the nanoparticles was measured by nitrogen adsorption. The NO{sub 2} sensing properties of the sensors based on unloaded and Pt-loaded WO{sub 3} nanoparticles were investigated. The results showed that the gas sensing properties of the Pt-loaded WO{sub 3} sensors were excellent to those of the unloaded one. Especially, 0.25 wt% Pt-loaded WO{sub 3} sensor showed highest response to NO{sub 2} than the others at low operating temperature of 150 °C. - Graphical abstract: The response of 0.25 wt% Pt-loaded WO3 sensor was 637 towards NO{sub 2} concentration of 10 ppm at 150 °C. - Highlights: • Unloaded and Pt-loaded WO{sub 3} nanoparticles for NO{sub 2} gas detection were synthesized by flame spray pyrolysis (FSP). • Gas sensing properties of the Pt-loaded WO{sub 3} sensors were excellent to those of the unloaded one. • 0.25 wt% Pt-loaded WO{sub 3} sensor showed highest response to NO{sub 2} at low operating temperature of 150 °C.

  18. Synthesis, characterization and photocatalytic activity of porous WO{sub 3}/TiO{sub 2} hollow microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Liuyang [Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Si, Zhichun, E-mail: emsztsinghua@126.com [Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Weng, Duan [Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); State Key Laboratory of New Ceramics and Fine Process, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Yao, Youwei [Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China)

    2014-09-15

    Porous WO{sub 3}/TiO{sub 2} hollow microspheres were prepared by a spray drying method for photodegradation of methylene blue and phenol. The catalysts were characterized by X-ray diffraction, Field Emission Scanning Electron Microscope, High Resolution Transmission Electron Microscope, N{sub 2} adsorption–desorption measurements, Raman spectrometer, UV–Vis Diffuse Reflectance Spectroscopy and Zeta-Meter measurements. The results showed that the tungsten oxides mainly existed in highly dispersed amorphous form on anatase when the loading amount of tungsten oxide was below 3 mol%. The improved photocatalytic activity under UV light irradiation of the WO{sub 3}/TiO{sub 2} catalyst mainly arises from the enhanced charge separation efficiency rather than the improved light absorbance by highly dispersed amorphous tungsten oxides. Highly dispersed amorphous WO{sub x} can form a shallowly trapped site due to its similar band structure with TiO{sub 2}. The strongly electron-withdrawing of tungsten oxide in highly dispersed state facilitates the electron transition between titanium and WO{sub x}, and consequently improves the charge separation. The enhanced acidity of catalyst by WO{sub x} in reactant environment also improved the charge separation efficiency due to the timely transition of holes and electrons accumulated on TiO{sub 2} and WO{sub x}, respectively. However, the improved photocatalytic activity under visible light irradiation of the WO{sub 3}/TiO{sub 2} catalyst mainly arises from light harvest. TiO{sub 2} containing 3 mol% WO{sub 3} displayed the highest photocatalytic activity under UV light irradiation while that containing 4 mol% WO{sub 3} present highest activity under visible light irradiation.

  19. Correlation between excited d-orbital electron lifetime in polaron dynamics and coloration of WO3 upon ultraviolet exposure

    Science.gov (United States)

    Lee, Young-Ahn; Han, Seung-Ik; Rhee, Hanju; Seo, Hyungtak

    2018-05-01

    Polarons have been suggested to explain the mechanism of the coloration of WO3 induced by UV light. However, despite the many experimental results that support small polarons as a key mechanism, direct observation of the carrier dynamics of polarons have yet to be reported. Here, we investigate the correlation between the electronic structure and the coloration of WO3 upon exposure to UV light in 5% H2/N2 gas and, more importantly, reveal photon-induced excited d-electron generation/relaxation via the W5+ oxidation state. The WO3 is fabricated by radio-frequency magnetron sputtering. X-ray diffraction patterns show that prepared WO3 is amorphous. Optical bandgap of 3.1 eV is measured by UV-vis before and after UV light. The results of Fourier transform infrared and Raman exhibit pristine WO3 is formed with surface H2O. The colored WO3 shows reduced state of W5+ state (34.3 eV) by using X-ray photoelectron spectroscopy. The valence band maximum of WO3 after UV light in H2 is shifted from mid gap to shallow donor by using ultraviolet photoelectron spectroscopy. During the exploration of the carrier dynamics, pump (700 nm)-probe (1000 nm) spectroscopy at the femtosecond scale was used. The results indicated that electron-phonon relaxation of UV-irradiated WO3, which is the origin of the polaron-induced local surface plasmonic effect, is dominant, resulting in slow decay (within a few picoseconds); in contrast, pristine WO3 shows fast decay (less than a picosecond). Accordingly, the long photoinduced carrier relaxation is ascribed to the prolonged hot-carrier lifetime in reduced oxides resulting in a greater number of free d-electrons and, therefore, more interactions with the W5+ sub-gap states.

  20. Promotion effect of Pt on a SnO2-WO3 material for NOx sensing

    Science.gov (United States)

    Wang, Chen-Yang; Hong, Zih-Siou; Wu, Ren-Jang

    2015-05-01

    Metal-oxide nanocomposites were prepared over screen-printed gold electrodes to be used as room-temperature NOx (nitric-oxide (NO) and nitrogen dioxide (NO2)) sensors. Various weight ratios of SnO2-WO3 and Pt loadings were used for NO sensing. The sensing materials were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface analysis. The NO-sensing results indicated that SnO2-WO3 (1:2) was more effective than other materials were. The sensor response (S=resistance of N2/resistance of NO=RN2/RNO) for detecting 1000 ppm of NO at room temperature was 2.6. The response time (T90) and recovery time (TR90) was 40 s and 86 s, respectively. By further loading with 0.5% Pt, the sensor response increased to 3.3. The response and recovery times of 0.5% Pt/SnO2-WO3 (1:2) were 40 s and 206 s, respectively. The linearity of the sensor response for a NO concentration range of 10-1000 ppm was 0.9729. A mechanism involving Pt promotion of the SnO2-WO3 heterojunction was proposed for NO adsorption, surface reaction, and adsorbed NO2 desorption.

  1. Highly Yb-doped KGd(WO4)2 thin-film amplifier

    NARCIS (Netherlands)

    Yong, Yean Sheng; Aravazhi, S.; Vázquez-Córdova, Sergio Andrés; García Blanco, Sonia Maria; Pollnau, Markus

    We report record-high small-signal gain of 1050 dB/cm at 981 nm wavelength in a KGd0.425Yb0.575(WO4)2 thin film. The sensitivity of gain to the shift of beam-focus position, which is critical under non-waveguiding conditions, is investigated.

  2. Crystal structures of the double perovskites Ba2Sr1-x Ca x WO6

    International Nuclear Information System (INIS)

    Fu, W.T.; Akerboom, S.; IJdo, D.J.W.

    2007-01-01

    Structures of the double perovskites Ba 2 Sr 1- x Ca x WO 6 have been studied by the profile analysis of X-ray diffraction data. The end members, Ba 2 SrWO 6 and Ba 2 CaWO 6 , have the space group I2/m (tilt system a 0 b - b - ) and Fm3-barm (tilt system a 0 a 0 a 0 ), respectively. By increasing the Ca concentration, the monoclinic structure transforms to the cubic one via the rhombohedral R3-bar phase (tilt system a - a - a - ) instead of the tetragonal I4/m phase (tilt system a 0 a 0 c - ). This observation supports the idea that the rhombohedral structure is favoured by increasing the covalency of the octahedral cations in Ba 2 MM'O 6 -type double perovskites, and disagrees with a recent proposal that the formation of the π-bonding, e.g., d 0 -ion, determines the tetragonal symmetry in preference to the rhombohedral one. - Graphical abstract: Enlarged sections showing the evolution of the basic (222) and (400) reflections in Ba 2 Sr 1- x Ca x WO 6 . Tick marks below are the positions of Bragg's reflections calculated using the space groups I2/m (x=0), R3-bar (x=0.25, 0.5 and 0.75) and Fm3-barm (x=1), respectively

  3. Status of 116Cd double β decay study with 116CdWO4 scintillators

    International Nuclear Information System (INIS)

    Bizzeti, P.G.; Fazzini, T.F.; Danevich, F.A.

    2001-01-01

    A new set-up with four enriched 116 CdWO 4 scintillators with the mass of 0.34 kg is presented. The measured half-life for 2ν2β decay as well as the T 1/2 limits for different modes of neutrinoless 2β decay of 116 Cd are reported

  4. An UV photochromic memory effect in proton-based WO3 electrochromic devices

    International Nuclear Information System (INIS)

    Zhang Yong; Lee, S.-H.; Mascarenhas, A.; Deb, S. K.

    2008-01-01

    We report an UV photochromic memory effect on a standard proton-based WO 3 electrochromic device. It exhibits two memory states, associated with the colored and bleached states of the device, respectively. Such an effect can be used to enhance device performance (increasing the dynamic range), re-energize commercial electrochromic devices, and develop memory devices

  5. Characterization of Porous WO3 Electrochromic Device by Electrochemical Impedance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Chien Chon Chen

    2013-01-01

    Full Text Available This paper concerns the microstructure of the anodic tungsten oxide (WO3 and its use in an electrochromic (EC glass device. When voltages between 100 V and 160 V were applied to tungsten film for 1 h under 0.4 wt. % NaF electrolyte, porous WO3 film was formed. The film, which had a large surface area, was used as electrochromic film for EC glass. The average transmittance in a visible region of the spectrum for a 144 cm2 EC device was above 75% in the bleached state and below 40% in the colored state, respectively. Repeatability using of the colored/bleached cycles was tested good by a cyclic voltammograms method. The internal impedance values under colored and bleached states were detected and simulated using an electrical impedance spectra (EIS technique. The EC glass impedance characteristics were simulated using resistors, capacitors, and Warburg impedance. The ITO/WO3, WO3/electrolyte, electrolyte/NiO, and NiO/ITO interfaces can be simulated using a resistance capacitance (RC parallel circuits, and bulk materials such as the indium tin oxide (ITO and conducting wire can be simulated by using a series of resisters.

  6. Super-Nernstian pH sensors based on WO3 nanosheets

    Science.gov (United States)

    Kuo, Chao-Yin; Wang, Shui-Jinn; Ko, Rong-Ming; Tseng, Hung-Hao

    2018-04-01

    The effects of the surface morphology of hydrothermally grown WO3 nanosheets (NSs) and sputtering WO3 film on the performance of pH sensing electrodes are presented and compared in the pH range of 2–12. Using a separated electrode of an extended-gate field-effect transistor (EGFET) configuration, the WO3 nanosheet (NS) pH sensor shows a sensitivity of 63.37 mV/pH, a good linearity of 0.9973, a low voltage hysteresis of 4.79 mV, and a low drift rate of 3.18 mV/h. In contrast, the film-type one shows a typical sensitivity of only 50.08 mV/pH and a linearity of 0.9932. The super-Nernstian response could be attributed to the significant increase in the number of surface ion adsorption sites of the NS structure and the occurrence of local electric field enhancement over the sharp edges and corners of WO3 NSs.

  7. Characteristics of W/O emulsions containing polymeric emulsifier PEG 30-dipolyhydroxystearate

    Directory of Open Access Journals (Sweden)

    Milinković Jelena R.

    2016-01-01

    Full Text Available Water-in-oil (W/O emulsions are dispersed systems which are often used in the pharmaceutical, cosmetic and food industries as products, or as carriers of active substances. It is well known that they are very unstable, so that selection of the emulsifier and properties of the oil and water phase are main factors affecting their stability. The aim of this paper was to examine the possibility of application of a lipophilic, polymeric emulsifier, PEG 30-dipolyhydroxystearate (CithrolTM DPHS, for stabilization of W/O emulsions. Behaviour of the emulsifier at W/O interfaces was determined by means of tensiometry. A series of emulsions were prepared with 20% (w/w of water and different types of oil. Droplet size, droplet size distribution, viscosity, and sedimentation stability during 30 days of storage at room temperature of the emulsions prepared with paraffin oil, olive oil, grape seed oil, and medium-chain triglycerides, stabilized with 1% CithrolTM DPHS, were determined. All investigated emulsions were stable for 30 days, except the one prepared with paraffin oil. The results of this study confirmed that PEG 30-dipolyhydroxylstearate is a good emulsifier and stabilizer of W/O emulsions which contain different types of oil. [Projekat Ministarstva nauke Republike Srbije, br. III46010

  8. Thermal oxidation of seeds for the hydrothermal growth of WO3 nanorods on ITO glass substrate

    International Nuclear Information System (INIS)

    Ng, Chai Yan; Abdul Razak, Khairunisak; Lockman, Zainovia

    2015-01-01

    This work reports a simple seed formation method for the hydrothermal growth of tungsten oxide (WO 3 ) nanorods. A WO 3 seed layer was prepared by thermal oxidation, where a W-sputtered substrate was heated and oxidized in a furnace. Oxidation temperatures and periods were varied at 400–550 °C and 5–60 min, respectively, to determine an appropriate seed layer for nanorod growth. Thermal oxidation at 500 °C for 15 min was found to produce a seed layer with sufficient crystallinity and good adhesion to the substrate. These properties prevented the seed from peeling off during the hydrothermal process, thereby allowing nanorod growth on the seed. The nanorod film showed better electrochromic behavior (higher current density of − 1.11 and + 0.65 mA cm −2 ) than compact film (lower current density of − 0.54 and + 0.28 mA cm −2 ). - Highlights: • A simple seed formation method (thermal oxidation) on sputtered W film is reported. • Crystalline seed with good adhesion to substrate is required for nanorod growth. • The appropriate temperature and period for seed formation were 500 °C and 15 min. • WO 3 nanorods exhibited higher electrochromic current density than WO 3 compact film.

  9. A. C. conduction behaviour in amorphous WO 3 /CEO 2 thin film ...

    African Journals Online (AJOL)

    A. C. conduction behaviour in amorphous WO3/CEO2 thin film. B Yagoubi, C A Hogarth, A Boukorrt. Abstract. No Abstract. Technologies Avancees Vol. 17 2005: pp. 5-8. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · http://dx.doi.org/10.4314/ta.v17i1.18478.

  10. An UV photochromic memory effect in proton-based WO3 electrochromic devices

    Science.gov (United States)

    Zhang, Yong; Lee, S.-H.; Mascarenhas, A.; Deb, S. K.

    2008-11-01

    We report an UV photochromic memory effect on a standard proton-based WO3 electrochromic device. It exhibits two memory states, associated with the colored and bleached states of the device, respectively. Such an effect can be used to enhance device performance (increasing the dynamic range), re-energize commercial electrochromic devices, and develop memory devices.

  11. Synthesis and characterization of MoO3–WO3 composite thin films ...

    Indian Academy of Sciences (India)

    Abstract. In order to achieve high colouration efficiency, MoO3–WO3 composite thin films have been successfully deposited on sodium silicate glass and silicon wafer (111) at 30 ◦C by a very simple novel wet process known as liquid phase deposition. The deposited films were annealed at different temperatures and ...

  12. Phase modification and surface plasmon resonance of Au/WO{sub 3} system

    Energy Technology Data Exchange (ETDEWEB)

    Bose, R. Jolly; Kavitha, V.S. [Department of Optoelectronics, University of Kerala, Kariyavattom, Thiruvananthapuram 691574, Kerala (India); Sudarsanakumar, C. [School of Pure and Applied Physics, Mahatma Gandhi University, Priyadarshini Hills, Kottayam 686560, Kerala (India); Pillai, V.P. Mahadevan, E-mail: vpmpillai9@gmail.com [Department of Optoelectronics, University of Kerala, Kariyavattom, Thiruvananthapuram 691574, Kerala (India)

    2016-08-30

    Highlights: • We have investigated the role of gold as catalyst and nucleation centers, for the crystallization and phase modification of tungsten oxide, in Au/WO{sub 3} matrix. • The phase change from triclinic WO{sub 3} to monoclinic W{sub 18}O{sub 49} is found to enhance with gold incorporation. • The surface plasmon resonance is observed in gold/tungsten oxide system with the appearance of an absorption band near the wavelength 604 nm. - Abstract: We report the action of gold as catalyst for the modification of phase from triclinic WO{sub 3} to monoclinic W{sub 18}O{sub 49} and nucleation centre for the formation of W{sub 18}O{sub 49} phase, in gold incorporated tungsten oxide films prepared by RF magnetron sputtering technique. A new band is observed near 925 cm{sup −1} in the Raman spectra of gold incorporated tungsten oxide films which is not observed in the pure tungsten oxide film. The intensity of this band enhances with gold content. A localized surface plasmon resonance (LSPR) band is observed near the wavelength 604 nm in gold incorporated tungsten oxide films. The integrated intensities of LSPR band and Raman band (∼925 cm{sup −1}) can be used for sensing the quantity of gold in the Au/WO{sub 3} matrix.

  13. Hydrothermal synthesis of hierarchical WO3 nanostructures for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Rashad, M.M.; Shalan, A.E.

    2014-01-01

    Hierarchical architectures consisting of one-dimensional (1D) nanostructures are of great interest for potential use in energy and environmental applications in recent years. In this work, hierarchical tungsten oxide (WO 3 ) has been synthesized via a facile hydrothermal route from ammonium metatungstate hydrate and implemented as photoelectrode for dye-sensitized solar cells. The urchin-like WO 3 micro-patterns are constructed by self-organized nanoscale length 1D building blocks, which are single crystalline in nature, grown along (001) direction and confirm an orthorhombic crystal phase. The obtained powders were investigated by XRD, SEM, TEM and UV-Vis Spectroscopy. The photovoltaic performance of dye-sensitized solar cells based on WO 3 photoanodes was investigated. With increasing the calcination temperature of the prepared nanopowders, the light-electricity conversion efficiency (η) was increased. The results were attributed to increase the crystallinity of the particles and ease of electron movement. The DSSC based on hierarchical WO 3 showed a short-circuit current, an open-circuit voltage, a fill factor, and a conversion efficiency of 4.241 mA/cm 2 , 0.656 V, 66.74, and 1.85 %, respectively. (orig.)

  14. Hydrothermal synthesis of hierarchical WO{sub 3} nanostructures for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Rashad, M.M. [Central Metallurgical Research and Development Institute (CMRDI), Helwan, P.O. Box 87, Cairo (Egypt); Shalan, A.E. [Central Metallurgical Research and Development Institute (CMRDI), Helwan, P.O. Box 87, Cairo (Egypt); Friedrich-Alexander-University of Erlangen-Nuremberg, Institute of Materials for Electronics and Energy Technology (i-MEET), Erlangen (Germany)

    2014-08-15

    Hierarchical architectures consisting of one-dimensional (1D) nanostructures are of great interest for potential use in energy and environmental applications in recent years. In this work, hierarchical tungsten oxide (WO{sub 3}) has been synthesized via a facile hydrothermal route from ammonium metatungstate hydrate and implemented as photoelectrode for dye-sensitized solar cells. The urchin-like WO{sub 3} micro-patterns are constructed by self-organized nanoscale length 1D building blocks, which are single crystalline in nature, grown along (001) direction and confirm an orthorhombic crystal phase. The obtained powders were investigated by XRD, SEM, TEM and UV-Vis Spectroscopy. The photovoltaic performance of dye-sensitized solar cells based on WO{sub 3} photoanodes was investigated. With increasing the calcination temperature of the prepared nanopowders, the light-electricity conversion efficiency (η) was increased. The results were attributed to increase the crystallinity of the particles and ease of electron movement. The DSSC based on hierarchical WO{sub 3} showed a short-circuit current, an open-circuit voltage, a fill factor, and a conversion efficiency of 4.241 mA/cm{sup 2}, 0.656 V, 66.74, and 1.85 %, respectively. (orig.)

  15. Ethanol vapour sensing properties of screen printed WO 3 thick films

    Indian Academy of Sciences (India)

    The ethanol vapour sensing properties of these thick films were investigated at different operating temperatures and ethanol vapour concentrations. The WO3 thick films exhibit excellent ethanol vapour sensing properties with a maximum sensitivity of ∼1424.6% at 400°C in air atmosphere with fast response and recovery ...

  16. Luminescent and structural properties of Zn_xMg_1_-_xWO_4 mixed crystals

    International Nuclear Information System (INIS)

    Krutyak, N.; Nagirnyi, V.; Spassky, D.; Tupitsyna, I.; Dubovik, A.; Belsky, A.

    2016-01-01

    The structural and luminescent properties of perspective scintillating Zn_xMg_1_-_xWO_4 mixed crystals were studied. The following characteristics were found to depend linearly on x value: the energy of several vibrational modes detected by Raman spectroscopy, the bandgap width deduced from the shift of the excitation spectrum onset of a self-trapped exciton (STE) emission, the position of thermally stimulated luminescence peaks. It is also shown that the thermal stability of the STE luminescence decreases gradually when x decreases. These data indicate that each Zn_xMg_1_-_xWO_4 mixed crystal is not a mixture of two constituents, but possesses its original crystalline structure, as well as optical and luminescent properties. - Highlights: • The structural and luminescent properties of Zn_xMg_1_-_xWO_4 were studied. • The energy of Raman modes, the bandgap width, TSL peak position linearly depend on x. • Each Zn_xMg_1_-_xWO_4 possesses its original crystalline structure.

  17. Structural phototransformation of WO{sub 3} thin films detected by photoacoustic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Pacheco, Argelia Perez, E-mail: ekargy@hotmail.com [Universidad Nacional Autonoma de Mexico, Laboratorio de Fotofisica y Peliculas Delgadas-CCADET, Ciudad Universitaria, Coyoacan, A.P. 70-186, C.P. 04510, Mexico, D.F. (Mexico); Montes de Oca, C. Oliva; Castaneda-Guzman, R.; Garcia, A. Esparza [Universidad Nacional Autonoma de Mexico, Laboratorio de Fotofisica y Peliculas Delgadas-CCADET, Ciudad Universitaria, Coyoacan, A.P. 70-186, C.P. 04510, Mexico, D.F. (Mexico)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer The phototransformation of WO{sub 3} thin films were studied by photoacoustic technique. Black-Right-Pointing-Pointer The phase transition in WO{sub 3} thin films was induced by laser irradiation fluence. Black-Right-Pointing-Pointer The onset and end of the phototransformation in the thin films was identified. Black-Right-Pointing-Pointer The ablation threshold for each sample was identified. - Abstract: The photoacoustic technique (PA) was used to detect the phase transformation from amorphous to crystalline state of tungsten oxide (WO{sub 3}) thin films induced by UV pulsed laser radiation at low energy (<1.5 mJ). The evolution of photoacoustic signal was studied by a correlation analysis, comparing successive signals at fluences ranging from 0 to 20 mJ/cm{sup 2}. In this interval, it was possible to observe structural changes and the ablation threshold in films due to incident laser fluence effect. Thin films of WO{sub 3} were deposited by DC reactive magnetron sputtering over glass substrates at different deposition times. The results obtained by correlation analysis were compared with Raman spectroscopy data.

  18. Managing SRS competition in a miniature visible Nd:YVO4/BaWO4 Raman laser.

    Science.gov (United States)

    Li, Xiaoli; Lee, Andrew J; Huo, Yujing; Zhang, Huaijin; Wang, Jiyang; Piper, James A; Pask, Helen M; Spence, David J

    2012-08-13

    We demonstrate the operation of a compact and efficient continuous wave (CW) self-Raman laser utilizing a Nd:YVO4 gain crystal and BaWO4 Raman crystal, generating yellow emission at 590 nm. We investigate the competition that occurs between Stokes lines in the Nd:YVO4 and BaWO4 crystals, and within the BaWO4 crystal itself. Through careful consideration of crystal length and orientation, we are able to suppress competition between Stokes lines, and generate pure yellow emission at 590 nm with output power of 194 mW for just 3.8 W pump power.

  19. Temperature dependent selective detection of hydrogen and acetone using Pd doped WO3/reduced graphene oxide nanocomposite

    Science.gov (United States)

    Kaur, Jasmeet; Anand, Kanica; Kohli, Nipin; Kaur, Amanpreet; Singh, Ravi Chand

    2018-06-01

    Reduced graphene oxide (RGO) and Pd doped WO3 nanocomposites were fabricated by employing electrostatic interactions between poly (diallyldimethylammonium chloride) (PDDA) modified Pd doped WO3 nanostructures and graphite oxide (GO) and studied for their gas sensing application. XRD, Raman, FTIR, FESEM-EDX, TEM, TGA, XPS and Photoluminescence techniques were used for characterization of as-synthesized samples. Gas sensing studies revealed that the sensor with optimized doping of 1.5 mol% Pd and 1 wt% GO shows temperature dependent selectivity towards hydrogen and acetone. The role of WO3, Pd and RGO has been discussed in detail for enhanced sensing performance.

  20. Synthesis and photoluminescence properties of Sm3+-doped CaWO4 nanoparticles

    International Nuclear Information System (INIS)

    Xiao Qi; Zhou Qitao; Li Ming

    2010-01-01

    The Sm 3+ -doped CaWO 4 nanoparticles were synthesized by hydrothermal method. The room temperature photoluminescence (PL) spectra of Sm 3+ -doped CaWO 4 nanoparticles doped with different Sm 3+ concentrations under 405 nm excitation have been investigated. The PL spectra showed four strong emission peaks at 460, 571, 609, and 653 nm. The first emission peak at 460 nm could be due to a structural defect of the lattice, an oxygen-deficient WO 3 complex. The other three emissions at 571, 609, and 653 nm were due to the f-f forbidden transitions of the 4f electrons of Sm 3+ , corresponding to 4 G 5/2 → 6 H 5/2 (571 nm), 6 H 7/2 (609 nm), and 6 H 9/2 (653 nm), respectively. In addition, the optimum Sm 3+ concentration in CaWO 4 nanoparticles for optical emission was determined to be 1.0%. The Sm 3+4 G 5/2 → 6 H 7/2 (609 nm) emission intensity of Sm 3+ -doped CaWO 4 nanoparticles significantly increased with the increase of Sm 3+ concentration, and showed a maximum when Sm 3+ doping content was 1.0%. If Sm 3+ concentration continued to increase, namely more than 1.0%, the Sm 3+4 G 5/2 → 6 H 7/2 emission intensity would decrease. The present materials might be a promising phosphor for white-light LED applications.

  1. Electrochromism and photocatalysis in dendrite structured Ti:WO3 thin films grown by sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Karuppasamy, A., E-mail: karuppasamy@psnacet.edu.in

    2015-12-30

    Graphical abstract: - Highlights: • Dendrite structured Ti doped WO{sub 3} (WTO) thin films are grown by co-sputtering. • Sputtering condition influences structure and surface morphology of WTO films. • Titanium doping and annealing lead to dendritic surface structures in WTO films. • Structural, optical, electrochromic and photocatalytic properties of WTO films. • Enhanced electrochromism and photocatalysis in dendrite structured WTO thin films. - Abstract: Titanium doped tungsten oxide (Ti:WO{sub 3}) thin films with dendrite surface structures were grown by co-sputtering titanium and tungsten in Ar + O{sub 2} atmosphere. Ti:WO{sub 3} thin films were deposited at oxygen flow rates corresponding to pressures in the range 1.0 × 10{sup −3}–5.0 × 10{sup −3} mbar. Argon flow rate and sputtering power densities for titanium (2 W/cm{sup 2}) and tungsten (3 W/cm{sup 2}) were kept constant. Ti:WO{sub 3} films deposited at an oxygen pressure of 5 × 10{sup −3} mbar are found to be better electrochromic and photocatalytic. They have high optical modulation (80% at λ = 550 nm), coloration efficiency (60 cm{sup 2}/C at λ = 550 nm), electron/ion storage and removal capacity (Qc: −22.01 mC/cm{sup 2}, Qa: 17.72 mC/cm{sup 2}), reversibility (80%) and methylene blue decomposition rate (−1.38 μmol/l d). The combined effects of titanium doping, dendrite surface structures and porosity leads to significant enhancement in the electrochromic and photocatalytic properties of Ti:WO{sub 3} films.

  2. Electrochromism and photocatalysis in dendrite structured Ti:WO3 thin films grown by sputtering

    International Nuclear Information System (INIS)

    Karuppasamy, A.

    2015-01-01

    Graphical abstract: - Highlights: • Dendrite structured Ti doped WO 3 (WTO) thin films are grown by co-sputtering. • Sputtering condition influences structure and surface morphology of WTO films. • Titanium doping and annealing lead to dendritic surface structures in WTO films. • Structural, optical, electrochromic and photocatalytic properties of WTO films. • Enhanced electrochromism and photocatalysis in dendrite structured WTO thin films. - Abstract: Titanium doped tungsten oxide (Ti:WO 3 ) thin films with dendrite surface structures were grown by co-sputtering titanium and tungsten in Ar + O 2 atmosphere. Ti:WO 3 thin films were deposited at oxygen flow rates corresponding to pressures in the range 1.0 × 10 −3 –5.0 × 10 −3 mbar. Argon flow rate and sputtering power densities for titanium (2 W/cm 2 ) and tungsten (3 W/cm 2 ) were kept constant. Ti:WO 3 films deposited at an oxygen pressure of 5 × 10 −3 mbar are found to be better electrochromic and photocatalytic. They have high optical modulation (80% at λ = 550 nm), coloration efficiency (60 cm 2 /C at λ = 550 nm), electron/ion storage and removal capacity (Qc: −22.01 mC/cm 2 , Qa: 17.72 mC/cm 2 ), reversibility (80%) and methylene blue decomposition rate (−1.38 μmol/l d). The combined effects of titanium doping, dendrite surface structures and porosity leads to significant enhancement in the electrochromic and photocatalytic properties of Ti:WO 3 films.

  3. Fiscal 1998 intellectual infrastructure project utilizing civil sector functions. Research and development project on prompt-effect type intellectual infrastructure creation (Research and development concerning relations between sintered body textural structure and material characteristics in fine ceramics); 1998 nendo minkan no kino wo katsuyoshita chiteki kiban jigyo seika hokokusho. Sokkogata chiteki kiban sosei kenkyu kaihatsu jigyo (fine ceramics no shoketsutai soshiki kozo to zairyo tokusei tono kankei ni kansuru kenkyu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Research and development was carried out involving fine ceramic sintered body textural structure evaluation methods for the development of process technologies for achieving higher quality and lower cost. Studies centered about a method for evaluating coarse pores and coarse grains in sintered bodies, relations between sintered body fracture strength and textural structure, and the standardization of evaluation methods. As the result, an evaluation method for observing pore structures in a sintered body flake specimen under an optical microscope and another for observing coarse grains under a polarization microscope were proposed. As for the effect of coarse defects on the fracture strength of ceramics, it was demonstrated experimentally and theoretically that coarse defects several tens of micrometers in size greatly affected the fracture strength. In the study of methods for sintered body grain size evaluation, findings were obtained about the processing of the specimen surface. (NEDO)

  4. THE DISCOVERY OF A RARE WO-TYPE WOLF-RAYET STAR IN THE LARGE MAGELLANIC CLOUD

    Energy Technology Data Exchange (ETDEWEB)

    Neugent, Kathryn F.; Massey, Philip [Lowell Observatory, 1400 W Mars Hill Road, Flagstaff, AZ 86001 (United States); Morrell, Nidia, E-mail: kneugent@lowell.edu, E-mail: phil.massey@lowell.edu, E-mail: nmorrell@lco.cl [Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile)

    2012-12-01

    While observing OB stars within the most crowded regions of the Large Magellanic Cloud, we happened upon a new Wolf-Rayet (WR) star in Lucke-Hodge 41, the rich OB association that contains S Doradus and numerous other massive stars. At first glance the spectrum resembled that of a WC4 star, but closer examination showed strong O VI {lambda}{lambda}3811, 34 lines, leading us to classify it as a WO4. This is only the second known WO in the LMC, and the first known WO4 (the other being a WO3). This rarity is to be expected due to these stars' short lifespans as they represent the most advanced evolutionary stage in a massive star's lifetime before exploding as supernovae. This discovery shows that while the majority of WRs within the LMC have been discovered, there may be a few WRs left to be found.

  5. THE DISCOVERY OF A RARE WO-TYPE WOLF–RAYET STAR IN THE LARGE MAGELLANIC CLOUD

    International Nuclear Information System (INIS)

    Neugent, Kathryn F.; Massey, Philip; Morrell, Nidia

    2012-01-01

    While observing OB stars within the most crowded regions of the Large Magellanic Cloud, we happened upon a new Wolf-Rayet (WR) star in Lucke-Hodge 41, the rich OB association that contains S Doradus and numerous other massive stars. At first glance the spectrum resembled that of a WC4 star, but closer examination showed strong O VI λλ3811, 34 lines, leading us to classify it as a WO4. This is only the second known WO in the LMC, and the first known WO4 (the other being a WO3). This rarity is to be expected due to these stars' short lifespans as they represent the most advanced evolutionary stage in a massive star's lifetime before exploding as supernovae. This discovery shows that while the majority of WRs within the LMC have been discovered, there may be a few WRs left to be found.

  6. CTAB-Assisted Hydrothermal Synthesis of WO3 Hierarchical Porous Structures and Investigation of Their Sensing Properties

    Directory of Open Access Journals (Sweden)

    Dan Meng

    2015-01-01

    Full Text Available WO3 hierarchical porous structures were successfully synthesized via cetyltrimethylammonium bromide- (CTAB- assisted hydrothermal method. The structure and morphology were investigated using scanning electron microscope, X-ray diffractometer, transmission electron microscopy, X-ray photoelectron spectra, Brunauer-Emmett-Teller nitrogen adsorption-desorption, and thermogravimetry and differential thermal analysis. The result demonstrated that WO3 hierarchical porous structures with an orthorhombic structure were constructed by a number of nanoparticles about 50–100 nm in diameters. The H2 gas sensing measurements showed that well-defined WO3 hierarchical porous structures with a large specific surface area exhibited the higher sensitivity compared with products without CTAB at all operating temperatures. Moreover, the reversible and fast response to H2 gas and good selectivity were obtained. The results indicated that the WO3 hierarchical porous structures are promising materials for gas sensors.

  7. High photocatalytic performance of BiOI/Bi{sub 2}WO{sub 6} toward toluene and Reactive Brilliant Red

    Energy Technology Data Exchange (ETDEWEB)

    Li Huiquan [School of Chemistry and Chemical Engineering, Fuyang Normal College, Fuyang 236041 (China); Key Laboratory of Mesoscopic Chemistry of MOE, Jiangsu Provincial Key Laboratory of Nanotechnology, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Cui Yumin, E-mail: cuiyumin0908@163.com [School of Chemistry and Chemical Engineering, Fuyang Normal College, Fuyang 236041 (China); Hong Wenshan [School of Chemistry and Chemical Engineering, Fuyang Normal College, Fuyang 236041 (China)

    2013-01-01

    Graphical abstract: When BiOI/Bi{sub 2}WO{sub 6} catalyst was exposed to UV or visible light, the electrons in the valence band of Bi{sub 2}WO{sub 6} would be excited into the conduction band and then injected into the more positive conduction band of BiOI. Therefore, the photoelectrons were generated from Bi{sub 2}WO{sub 6} and transferred across the interface between BiOI and Bi{sub 2}WO{sub 6} to the surface of BiOI, leaving the photogenerated holes in the valence band of Bi{sub 2}WO{sub 6}. In this way, the photoinduced electron-hole pairs were effectively separated. Highlights: Black-Right-Pointing-Pointer BiOI sensitized Bi{sub 2}WO{sub 6} catalysts were successfully prepared by a facile method. Black-Right-Pointing-Pointer The 13.2% BiOI/Bi{sub 2}WO{sub 6} catalyst exhibits higher photoactivities than P25. Black-Right-Pointing-Pointer A possible transfer process of photogenerated carriers was proposed. - Abstract: BiOI sensitized nano-Bi{sub 2}WO{sub 6} photocatalysts with different BiOI contents were successfully synthesized by a facile deposition method at room temperature, and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) high-resolution transmission electron microscopy (HR-TEM), photoluminescence (PL) spectra, UV-vis diffuse reflection spectroscopy (UV-vis DRS) and Brunauer-Emmett-Teller (BET) surface area measurements. The photocatalytic activity of BiOI/Bi{sub 2}WO{sub 6} was evaluated by the photo-degradation of Reactive Brilliant Red (X-3B) in suspended solution and toluene in gas phase. It has been shown that the BiOI/Bi{sub 2}WO{sub 6} catalysts exhibit a coexistence of both tetragonal BiOI and orthorhombic Bi{sub 2}WO{sub 6} phases. With increasing BiOI content, the absorption intensity of BiOI/Bi{sub 2}WO{sub 6} catalysts increases in the 380-600 nm region and the absorption edge shifts significantly to longer wavelengths as compared to pure Bi{sub 2}WO{sub 6}. The 13.2% BiOI/Bi{sub 2}WO{sub 6} catalyst exhibits

  8. Pronounced effects of the nominal concentrations of WO3 and Ag: WO3 nano-plates (obtained by a co-precipitation method) on their structural, morphological and optical properties

    Science.gov (United States)

    Rajendran, V.; Deepa, B.

    2018-03-01

    Tungsten oxide and different concentration of silver (Ag)-doped tungsten oxide nano material were synthesized by co-precipitation technique. The functional vibrations, structure, and morphology of as-prepared nano material were studied by Fourier transmission infrared spectroscopy, X-ray diffraction, scanning electron microscopy (SEM) and High-resolution transmission electron microscopy (HR-TEM) techniques. The SEM and HR-TEM analysis revealed the formation of nano-plate/nano rods with an average diameter of 40-80 nm diameter and 1-1.5 mm length. Fluorescence (PL) and UV-visible absorption techniques have been used to study the optical properties of the prepared nanoparticles. The observed red shift in the visible absorption spectra confirmed the promoted electron-phonon interaction in WO3 and Ag: WO3 nanoparticles compared to bulk structures. The photoluminescence of nanocrystalline Ag2+ doped WO3 exhibited a strong violet-blue, blue-green emission. Concentration dependence of the emission intensity of Ag2+ in WO3 was studied, and the significant concentration was found to be 0.5% of Ag: WO3. The effluent dye degradation executed for the 0.5% of Ag: WO3 sample under the visible light which reveals the highest degradation efficiency in appropriate time.

  9. Solar photocatalytic activity of TiO2 modified with WO3 on the degradation of an organophosphorus pesticide

    International Nuclear Information System (INIS)

    Ramos-Delgado, N.A.; Gracia-Pinilla, M.A.; Maya-Treviño, L.; Hinojosa-Reyes, L.; Guzman-Mar, J.L.; Hernández-Ramírez, A.

    2013-01-01

    Highlights: • TiO 2 and WO 3 /TiO 2 (2 and 5%) were tested in the photocatalytic malathion degradation. • The use of solar radiation in the photocatalytic degradation process was evaluated. • Modified catalyst showed greater photocatalytic activity than pure TiO 2 . • The mineralization rate was improved when WO 3 content on TiO 2 was 2%. -- Abstract: In this study, the solar photocatalytic activity (SPA) of WO 3 /TiO 2 photocatalysts synthesized by the sol–gel method with two different percentages of WO 3 (2 and 5%wt) was evaluated using malathion as a model contaminant. For comparative purpose bare TiO 2 was also prepared by sol–gel process. The powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectance UV–vis spectroscopy (DRUV–vis), specific surface area by the BET method (SSA BET ), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy with a high annular angle dark field detector (STEM-HAADF). The XRD, Raman, HRTEM and STEM-HAADF analyses indicated that WO 3 was present as a monoclinic crystalline phase with nanometric cluster sizes (1.1 ± 0.1 nm for 2% WO 3 /TiO 2 and 1.35 ± 0.3 nm for 5% WO 3 /TiO 2 ) and uniformly dispersed on the surface of TiO 2 . The particle size of the materials was 19.4 ± 3.3 nm and 25.6 ± 3 nm for 2% and 5% WO 3 /TiO 2 , respectively. The SPA was evaluated on the degradation of commercial malathion pesticide using natural solar light. The 2% WO 3 /TiO 2 photocatalyst exhibited the best photocatalytic activity achieving 76% of total organic carbon (TOC) abatement after 300 min compared to the 5% WO 3 /TiO 2 and bare TiO 2 photocatalysts, which achieved 28 and 47% mineralization, respectively. Finally, experiments were performed to assess 2% WO 3 /TiO 2 catalyst activity on repeated uses; after several successive cycles its photocatalytic activity was retained showing long-term stability

  10. Synthesis of WO{sub 3} nanoparticles by citric acid-assisted precipitation and evaluation of their photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez-Martínez, D. [Departamento de Ecomateriales y Energía, Facultad de Ingeniería Civil (UANL), Ciudad Universitaria, C.P. 66451, San Nicolás de los Garza, N.L. (Mexico); Martínez-de la Cruz, A., E-mail: azael70@yahoo.com.mx [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451, San Nicolás de los Garza, N.L. (Mexico); López-Cuéllar, E. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451, San Nicolás de los Garza, N.L. (Mexico)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► WO{sub 3} nanoparticles were synthesized by a simple citric acid-assisted precipitation. ► WO{sub 3} photocatalyst was able to the partial mineralization of rhB, IC and MO. ► WO{sub 3} can be considered as a photocatalyst active under visible light irradiation. -- Abstract: WO{sub 3} nanoparticles were synthesized by citric acid-assisted precipitation method using a 1:1.5 molar ratio of ammonium paratungstate hydrate (H{sub 42}N{sub 10}O{sub 42}W{sub 12}·xH{sub 2}O):citric acid (C{sub 6}H{sub 8}O{sub 7}). The formation of monoclinic crystal structure of WO{sub 3} at different temperatures was confirmed by X-ray powder diffraction (XRD). The characterization of the samples synthesized was complemented by transmission electron microscopy (TEM), Brunauer–Emmitt–Teller surface area (BET) and diffuse reflectance spectroscopy (DRS). According to the thermal treatment followed during the synthesis of WO{sub 3}, the morphology of the nanoparticles formed was characterized by rectangular and ovoid shapes. The photocatalytic activity of WO{sub 3} obtained under different experimental conditions was evaluated in the degradation of rhodamine B (rhB), indigo carmine (IC), methyl orange (MO), and Congo red (CR) in aqueous solution under UV and UV–vis radiation. The highest photocatalytic activity was observed in the sample obtained by thermal treatment at 700 °C. In general, the sequence of degradation of the organic dyes was: indigo carmine (IC) > rhodamine B (rhB) > methyl orange (MO) > Congo red (CR). The mineralization degree of organic dyes by WO{sub 3} photocatalysts was determined by total organic carbon analysis (TOC) reaching percentages of mineralization of 82% (rhB), 85% (IC), 28% (MO), and 7% (CR) for 96 h of lamp irradiation.

  11. Mesoporous WN/WO3-Composite Nanosheets for the Chemiresistive Detection of NO2 at Room Temperature

    OpenAIRE

    Fengdong Qu; Bo He; Rohiverth Guarecuco; Minghui Yang

    2016-01-01

    Composite materials, which can optimally use the advantages of different materials, have been studied extensively. Herein, hybrid tungsten nitride and oxide (WN/WO3) composites were prepared through a simple aqueous solution route followed by nitriding in NH3, for application as novel sensing materials. We found that the introduction of WN can improve the electrical properties of the composites, thus improving the gas sensing properties of the composites when compared with bare WO3. The highe...

  12. Synthesis of WO3 nanoparticles by citric acid-assisted precipitation and evaluation of their photocatalytic properties

    International Nuclear Information System (INIS)

    Sánchez-Martínez, D.; Martínez-de la Cruz, A.; López-Cuéllar, E.

    2013-01-01

    Graphical abstract: Display Omitted Highlights: ► WO 3 nanoparticles were synthesized by a simple citric acid-assisted precipitation. ► WO 3 photocatalyst was able to the partial mineralization of rhB, IC and MO. ► WO 3 can be considered as a photocatalyst active under visible light irradiation. -- Abstract: WO 3 nanoparticles were synthesized by citric acid-assisted precipitation method using a 1:1.5 molar ratio of ammonium paratungstate hydrate (H 42 N 10 O 42 W 12 ·xH 2 O):citric acid (C 6 H 8 O 7 ). The formation of monoclinic crystal structure of WO 3 at different temperatures was confirmed by X-ray powder diffraction (XRD). The characterization of the samples synthesized was complemented by transmission electron microscopy (TEM), Brunauer–Emmitt–Teller surface area (BET) and diffuse reflectance spectroscopy (DRS). According to the thermal treatment followed during the synthesis of WO 3 , the morphology of the nanoparticles formed was characterized by rectangular and ovoid shapes. The photocatalytic activity of WO 3 obtained under different experimental conditions was evaluated in the degradation of rhodamine B (rhB), indigo carmine (IC), methyl orange (MO), and Congo red (CR) in aqueous solution under UV and UV–vis radiation. The highest photocatalytic activity was observed in the sample obtained by thermal treatment at 700 °C. In general, the sequence of degradation of the organic dyes was: indigo carmine (IC) > rhodamine B (rhB) > methyl orange (MO) > Congo red (CR). The mineralization degree of organic dyes by WO 3 photocatalysts was determined by total organic carbon analysis (TOC) reaching percentages of mineralization of 82% (rhB), 85% (IC), 28% (MO), and 7% (CR) for 96 h of lamp irradiation.

  13. Radiation Damage Mechanism in PbWO4 Crystal and Radiation Hardness Quality Control of PWO Scintillators for CMS

    CERN Document Server

    Baccaro, Stefania; Borgia, Bruno; Cavallari, Francesca; Cecilia, Angelica; Dafinei, Ioan; Diemoz, Marcella; Lecoq, Paul; Longo, Egidio; Montecchi, Marco; Organtini, Giovanni; Salvatori, S

    1997-01-01

    The optical damage induced by UV light in PbWO4 crystals is found to be similar to that induced by g radiation. Due to the peculiarities of optical absorption in PbWO4, the damage induced by UV light is a bulk process. This fact has important consequences for the approach to be adopted both for the use of the crystal as scintillator and for the qualification methods foreseen in the Regional Centres of the ECAL CMS Collaboration.

  14. Photoreduction of non-noble metal Bi on the surface of Bi{sub 2}WO{sub 6} for enhanced visible light photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaojing [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, No. 8, Xindu Road, Xindu District, Chengdu 610500 (China); The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, No. 8, Xindu Road, Xindu District, Chengdu 610500 (China); Yu, Shan; Liu, Yang; Zhang, Qian [The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, No. 8, Xindu Road, Xindu District, Chengdu 610500 (China); Zhou, Ying, E-mail: yzhou@swpu.edu.cn [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, No. 8, Xindu Road, Xindu District, Chengdu 610500 (China); The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, No. 8, Xindu Road, Xindu District, Chengdu 610500 (China)

    2017-02-28

    Highlights: • Bi{sub 2}WO{sub 6}-Bi composite was synthesized by in situ photoreduction of Bi{sub 2}WO{sub 6}. • Bi{sub 2}WO{sub 6}-Bi exhibits improved photocatalytic efficiency towards degradation of Rhodamine B. • The generation of elemental Bi in Bi{sub 2}WO{sub 6}-Bi induces vacancy and structure distortion of Bi{sub 2}WO{sub 6}. • The surface oxygen adsorption mode changes from hydroxyl group on Bi{sub 2}WO{sub 6} to molecular oxygen on Bi{sub 2}WO{sub 6}-Bi. - Abstract: In this report, Bi{sub 2}WO{sub 6}-Bi composite was prepared through an in situ photoreduction method and was characterized systematically by X-Ray diffraction, transmission electron microscopy, X-Ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The as-prepared Bi{sub 2}WO{sub 6}-Bi maintains the same crystal structure with the pristine Bi{sub 2}WO{sub 6} regardless of some surface defects. Nevertheless, these surface defects result in the change of surface oxygen adsorption mode from hydroxyl to molecular oxygen on Bi{sub 2}WO{sub 6}. Photocatalytic activity over Bi{sub 2}WO{sub 6}-Bi is 2.4 times higher than that of Bi{sub 2}WO{sub 6} towards the degradation of organic dye Rhodamine B (RhB) under visible light irradiation (λ > 420 nm). A deep study shows that cleavage of benzene ring is the main pathway for RhB degradation over Bi{sub 2}WO{sub 6}, but both the benzene cleavage and de-ethylation pathway coexist for RhB decomposition in the presence of Bi{sub 2}WO{sub 6}-Bi as the photocatalyst. Photoelectrochemical study including transient photocurrent tests and electrochemical impedance spectroscopy measurements shows that Bi{sub 2}WO{sub 6}-Bi could facilitate the charge transfer process compared to Bi{sub 2}WO{sub 6}. These data above has indicated a new insight into the promotion mechanism based on Bi related heterostructures.

  15. Understanding the conductive channel evolution in Na:WO3-x-based planar devices

    Science.gov (United States)

    Shang, Dashan; Li, Peining; Wang, Tao; Carria, Egidio; Sun, Jirong; Shen, Baogen; Taubner, Thomas; Valov, Ilia; Waser, Rainer; Wuttig, Matthias

    2015-03-01

    An ion migration process in a solid electrolyte is important for ion-based functional devices, such as fuel cells, batteries, electrochromics, gas sensors, and resistive switching systems. In this study, a planar sandwich structure is prepared by depositing tungsten oxide (WO3-x) films on a soda-lime glass substrate, from which Na+ diffuses into the WO3-x films during the deposition. The entire process of Na+ migration driven by an alternating electric field is visualized in the Na-doped WO3-x films in the form of conductive channel by in situ optical imaging combined with infrared spectroscopy and near-field imaging techniques. A reversible change of geometry between a parabolic and a bar channel is observed with the resistance change of the devices. The peculiar channel evolution is interpreted by a thermal-stress-induced mechanical deformation of the films and an asymmetric Na+ mobility between the parabolic and the bar channels. These results exemplify a typical ion migration process driven by an alternating electric field in a solid electrolyte with a low ion mobility and are expected to be beneficial to improve the controllability of the ion migration in ion-based functional devices, such as resistive switching devices.An ion migration process in a solid electrolyte is important for ion-based functional devices, such as fuel cells, batteries, electrochromics, gas sensors, and resistive switching systems. In this study, a planar sandwich structure is prepared by depositing tungsten oxide (WO3-x) films on a soda-lime glass substrate, from which Na+ diffuses into the WO3-x films during the deposition. The entire process of Na+ migration driven by an alternating electric field is visualized in the Na-doped WO3-x films in the form of conductive channel by in situ optical imaging combined with infrared spectroscopy and near-field imaging techniques. A reversible change of geometry between a parabolic and a bar channel is observed with the resistance change of the

  16. Structural studies of WO3-TeO2 glasses by high-Q-neutron diffraction and Raman spectroscopy

    International Nuclear Information System (INIS)

    Khanna, A.; Kaur, A.; Krishna, P.S.R.; Shinde, A.B.

    2013-01-01

    Glasses from the system: xWO 3 -(100-x)TeO 2 (x=15, 20 and 25 mol %) were prepared by melt quenching technique and characterized by density, UV-visible absorption spectroscopy, Differential Scanning Calorimetry (DSC), Raman spectroscopy and high-Q neutron diffraction measurements. Glass density and glass transition temperature increased with increase in WO 3 concentration, Raman spectroscopy indicated the conversion of TeO 4 units into TeO 3 units with increase in WO 3 content. The increase in glass transition temperature with the incorporation of WO 3 was attributed to the increase in average bond strength of the glass network since the bond dissociation energy of W-O bonds (672 kJ/mol) is significantly higher than that of Te-O bonds (376 kJ/mol). UV-visible studies found a very strong optical absorption band due to W 6+ ions, just below the absorption edge. High-Q neutron diffraction measurements were performed on glasses and radial distribution function analyses revealed changes in W-O and Te-O correlations in the glass network. The findings about changes in glass structure from neutron diffraction studies were consistent with structural information obtained from Raman spectroscopy and structure-property correlations were made. (author)

  17. Hydrothermal deposition and photochromic performances of three kinds of hierarchical structure arrays of WO3 thin films

    International Nuclear Information System (INIS)

    Ding, Defang; Shen, Yi; Ouyang, Yali; Li, Zhen

    2012-01-01

    Three kinds of tungsten oxide (WO 3 ) thin films have been fabricated by a simple hydrothermal deposition method. Scanning electron microscopy images of the products revealed that the capping agents did impact the microstructure of WO 3 films. Films prepared without capping agents were ordered nanorod arrays, while the ones obtained with ethanol and oxalic acid revealed peeled-orange-like and cauliflower-like hierarchical structure arrays, respectively. Both of the two hierarchical structures were composed of much thinner nanorods compared with the one obtained without capping agents. All the WO 3 films exhibited good photochromic properties and the two with inducers performed even better, which could be due to the changes in the microstructure that increased the amount of photogenerated electron–hole pairs and the proton diffusion rates. - Highlights: ► Ordered WO 3 nanorod arrays were prepared by hydrothermal deposition process. ► Two hierarchical WO 3 structure arrays were obtained with ethanol and oxalic acid. ► Mechanism for the improved photochromic performances of WO 3 films is proposed.

  18. Ultrathin percolated WO{sub 3} cluster film and its resistive response to H{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Meng [Research Center for Solid State Physics and Materials, School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009 (China); Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China); Wong, Man Hon; Huang, Jian Xing [Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China); Ong, Chung Wo, E-mail: c.w.ong@polyu.edu.hk [Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

    2014-11-05

    Highlights: • Ultrathin percolated network of WO{sub 3} clusters was fabricated. • The WO{sub 3} clusters are modeled by spherical caps connected by ultrafine linkages. • The ultrathin percolated network of WO{sub 3} clusters shows fast response rate to H{sub 2}. • The fast response is attributed to the rapid electrical switching of the linkages. • Improved H{sub 2} sensing properties may be achieved if narrower linkages are used. - Abstract: Thin films composed of tungsten oxide (WO{sub 3}) nanoclusters were fabricated by oxidizing supersonic cluster beam deposited tungsten films at various temperatures. Oxidation at 700 °C resulted in aggregation of the deposits, forming a percolated network of WO{sub 3} spherical caps connected by fine links. The resistance response of the palladium-(Pd-) coated film sample to hydrogen (H{sub 2}) was investigated. The response rate was faster than those of other samples oxidized at lower temperatures. This is the result of the rapid electrical switching of the intercluster links between the highly resistive depleted state and conducting hydrogenated state. The possibility of improving the H{sub 2} sensing response rate with the use of the percolated WO{sub 3} film structure is illustrated.

  19. A facile synthesis of ZnWO{sub 4} nanoparticles by microwave assisted technique and its application in photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Garadkar, K.M., E-mail: kmg_chem@unishivaji.ac.in [Nanomaterials Research Laboratory, Department of Chemistry, Shivaji University, Kolhapur 416 004, MS (India); Ghule, L.A. [Nanomaterials Research Laboratory, Department of Chemistry, Shivaji University, Kolhapur 416 004, MS (India); Sapnar, K.B.; Dhole, S.D. [Microtron Accelerator Laboratory, Department of Physics, University of Pune, Pune 411 007, MS (India)

    2013-03-15

    Highlights: ► Nanocrystalline ZnWO{sub 4} particles were successfully prepared by a microwave method. ► Spherical morphology with a 10 nm size. ► The band is 3.4 eV. ► The photodegradation of RhB was 95% within 25 min. - Abstract: A simple microwave assisted technique has been successfully developed to synthesize ZnWO{sub 4} nanoparticles. The X-ray diffraction results indicated that the synthesized nanoparticles exhibited only wolframite structure. Structural, morphological and optical properties of ZnWO{sub 4} nanoparticles have been analyzed by XRD, SEM, TEM EDAX, UV–vis and FT-IR spectral measurements. The transmission electron microscopy (TEM) image revealed that particle size of ZnWO{sub 4} nanoparticles was found to be 10 nm, the band-gap of ZnWO{sub 4} nanoparticles was found to be 3.4 eV. The photocatalytic activities for aqueous Rhodamine B and Methylene Blue samples were investigated and observed that ZnWO{sub 4} nanoparticles exhibited highly enhanced photocatalytic activity towards RhB than MB.

  20. Synthesis of ZnWO{sub 4} Electrode with tailored facets: Deactivating the Microorganisms through Photoelectrocatalytic methods

    Energy Technology Data Exchange (ETDEWEB)

    Zhan, Su [Department of Materials Science and Engineering, Dalian Maritime University, Dalian 116026 (China); Zhou, Feng, E-mail: zhoufeng99@mails.tsinghua.edu.cn [Department of Materials Science and Engineering, Dalian Maritime University, Dalian 116026 (China); Huang, Naibao; Liu, Yujun; He, Qiuchen; Tian, Yu; Yang, Yifan [Department of Materials Science and Engineering, Dalian Maritime University, Dalian 116026 (China); Ye, Fei [Department of Materials Science and Engineering, Dalian University of Technology, Dalian 116026 (China)

    2017-01-01

    Highlights: • ZnWO{sub 4} with different exposed facets was synthesized by the hydrothermal method. • The reactive facets were tailored by varying the solution pH. • The photoelectrocatalysis was more efficient in deactivating the microorganism. - Abstract: The exotic invasive species from the ballast water in the ship will bring about serious damages to ecosystem. Photocatalyst films have been widely studied for sterilization. In this study, ZnWO{sub 4} with different exposed facets was synthesized by hydrothermal method, and ZnWO{sub 4} film electrodes have been applied in ballast water treatment through the electro-assisted photocatalytic system. Then the samples were investigated by X-ray diffraction (XRD), X-ray photo-electron spectroscopy (XPS), Field emission on scanning electron microcopy (FE-SEM), Transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy (DRS), BET specific surface area analysis, Fourier transform infrared (FT-IR) and Electrochemical impedance spectra (EIS). ZnWO{sub 4} with an appropriate exposure of (0 1 1) facets ratio exhibited the best photocatalytic and photoelectrocatalytic activities. The microorganisms deactivated completely in 10 min by ZnWO{sub 4} films with 3 V bias. The mechanisms of (0 1 1) facets enhanced the photocatalytic and photoelectrocatalytic activities which were deduced based on the calculated result from the first principles. Simultaneously, appropriate exposed facets and applied bias could reduce the recombination of the photogenerated electron-hole pairs, and improve the photocatalytic activities of ZnWO{sub 4}.

  1. CdWO{sub 4}-on-MEH-PPV:PS as a candidate for real-time dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.M. [Laboratory of Polymers and Electronic Properties of Materials, UFOP, 35400-000 (Brazil); Novais, S.M.V.; Silva, E.S.S. [Group of Advanced Ceramic Materials, UFS, 49100-000 (Brazil); Schimitberger, T. [Laboratory of Polymers and Electronic Properties of Materials, UFOP, 35400-000 (Brazil); Macedo, Z.S. [Group of Advanced Ceramic Materials, UFS, 49100-000 (Brazil); Bianchi, R.F., E-mail: bianchi@iceb.ufop.br [Laboratory of Polymers and Electronic Properties of Materials, UFOP, 35400-000 (Brazil)

    2012-10-15

    We report on the investigations about the modification of optical properties induced by X-rays onto film detectors of cadmium tungstate (CdWO{sub 4}), poly[2-methoxy-5(2 Prime -ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) and polystyrene (PS) This device takes advantage of reduction of spectral overlap between the radioluminescence (RL) of CdWO{sub 4} and the absorption of MEH-PPV as it is exposed to radiation, forming the basis of a new dosimeter that is capable of converting the orange-red radioluminescence of PS:MEH-PPV:CdWO{sub 4} into green. We propose an explanation of the optical processes occurring in MEH-PPV:CdWO{sub 4} in terms of the radiation hardness of CdWO{sub 4} combined to the RL-induced degradation of MEH-PPV. Highlights: Black-Right-Pointing-Pointer Thin composite film dosimeters using a combination of a scintillator crystal and a light-emitting polymer. Black-Right-Pointing-Pointer A X-ray dose detector based on MEH-PPV/CdWO{sub 4} materials which are rarely seen together. Black-Right-Pointing-Pointer A new smart, disposable and easy-to-read organic-inorganic radiation detector.

  2. Preparation and photoelectric properties of p-CaFe2O4/n-WO3 composites

    International Nuclear Information System (INIS)

    Wan, Ruiqin; Jia, Caihong; Zhang, Weifeng

    2012-01-01

    Highlights: ► Surface photovoltage spectroscopy investigation on p-CaFe 2 O 4 /n-WO 3 composites. ► The photovoltaic response is enhanced in p-CaFe 2 O 4 /n-WO 3 composites. ► The multielectron process and high rate of carrier migration in WO 3 . - Abstract: Composites of p-CaFe 2 O 4 /n-WO 3 are prepared via a sol–gel technique. Their structures and optical properties are characterized with X-ray diffraction, scanning electron microscopy and UV–vis absorption spectroscopy. The photoelectric characteristics are investigated by surface photovoltage spectroscopy combined with electric field induced surface photovoltage spectroscopy. The results indicate that CaFe 2 O 4 can well form a p–n type composite with WO 3 , and the intensity and spectral region of surface photovoltaic response for the composites are strongly dependent on the molar ratio of two components. The enhancement in photoelectric properties and the effective separation of photogenerated carriers could be attributed to the energy level matching between the two components, multielectron process and the high migration rate in WO 3 .

  3. Hydrothermal deposition and photochromic performances of three kinds of hierarchical structure arrays of WO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Defang; Shen, Yi, E-mail: sysy7373@163.com; Ouyang, Yali; Li, Zhen

    2012-10-01

    Three kinds of tungsten oxide (WO{sub 3}) thin films have been fabricated by a simple hydrothermal deposition method. Scanning electron microscopy images of the products revealed that the capping agents did impact the microstructure of WO{sub 3} films. Films prepared without capping agents were ordered nanorod arrays, while the ones obtained with ethanol and oxalic acid revealed peeled-orange-like and cauliflower-like hierarchical structure arrays, respectively. Both of the two hierarchical structures were composed of much thinner nanorods compared with the one obtained without capping agents. All the WO{sub 3} films exhibited good photochromic properties and the two with inducers performed even better, which could be due to the changes in the microstructure that increased the amount of photogenerated electron-hole pairs and the proton diffusion rates. - Highlights: Black-Right-Pointing-Pointer Ordered WO{sub 3} nanorod arrays were prepared by hydrothermal deposition process. Black-Right-Pointing-Pointer Two hierarchical WO{sub 3} structure arrays were obtained with ethanol and oxalic acid. Black-Right-Pointing-Pointer Mechanism for the improved photochromic performances of WO{sub 3} films is proposed.

  4. Effect of Post-annealing on the Electrochromic Properties of Layer-by-Layer Arrangement FTO-WO3-Ag-WO3-Ag

    Science.gov (United States)

    Hoseinzadeh, S.; Ghasemiasl, R.; Bahari, A.; Ramezani, A. H.

    2018-03-01

    In the current study, composites of tungsten trioxide (W03) and silver (Ag) are deposited in a layer-by-layer electrochromic (EC) arrangement onto a fluorine-doped tin oxide coated glass substrate. Tungsten oxide nanoparticles are an n-type semiconductor that can be used as EC cathode material. Nano-sized silver is a metal that can serve as an electron trap center that facilitates charge departure. In this method, the WO3 and Ag nanoparticle powder were deposited by physical vapor deposition onto the glass substrate. The fabricated electrochromic devices (ECD) were post-annealed to examine the effect of temperature on their EC properties. The morphology of the thin film was characterized by scanning electron microscopy and atomic force microscopy. Structural analysis showed that the addition of silver dopant increased the size of the aggregation of the film. The film had an average approximate roughness of about 17.8 nm. The electro-optical properties of the thin film were investigated using cyclic voltammetry and UV-visible spectroscopy to compare the effects of different post-annealing temperatures. The ECD showed that annealing at 200°C provided better conductivity (maximum current of about 90 mA in the oxidation state) and change of transmittance (ΔT = 90% at the continuous switching step) than did the other thin films. The optical band gaps of the thin film showed that it allowed direct transition at 3.85 eV. The EC properties of these combinations of coloration efficiency and response time indicate that the WO3-Ag-WO3-Ag arrangement is a promising candidate for use in such ECDs.

  5. Photogenerated cathode protection properties of nano-sized TiO2/WO3 coating

    International Nuclear Information System (INIS)

    Zhou Minjie; Zeng Zhenou; Zhong Li

    2009-01-01

    Nano-sized TiO 2 /WO 3 bilayer coatings were prepared on type 304 stainless steel substrate by sol-gel method. The performance of photo-electrochemical and photogenerated cathode protection of the coating was investigated by the electrochemical method. The results show that the bilayer coating with four TiO 2 layers and three WO 3 layers exhibits the highest photo-electrochemical efficiency and the best corrosion resistance property. Type 304 stainless steel with the coating can maintain cathode protection for 6 h in the dark after irradiation by UV illumination for 1 h. In addition, the mechanism of the photogenerated cathode protection for the bilayer coating was also explored.

  6. Low-temperature synthesis and structural properties of ferroelectric K 3WO 3F 3 elpasolite

    Science.gov (United States)

    Atuchin, V. V.; Gavrilova, T. A.; Kesler, V. G.; Molokeev, M. S.; Aleksandrov, K. S.

    2010-06-01

    Low-temperature ferroelectric G2 polymorph of K 3WO 3F 3 has been prepared by chemical synthesis. Structural and chemical properties of the final product have been evaluated with X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Structure parameters of G2-K 3WO 3F 3 are refined by the Rietveld method from XRD data measured at room temperature (space group Cm, Z = 2, a = 8.7350(3) Å, b = 8.6808(5) Å, c = 6.1581(3) Å, β = 135.124(3) Å, V = 329.46(3) Å 3; RB = 2.47%). Partial ordering of oxygen and fluorine atoms has been found over anion positions. Mechanism of ferroelectric phase transition in A 2BMO 3F 3 oxyfluorides is discussed.

  7. Effect of solution chemistry on the characteristics of hydrothermally grown WO_3 for electroactive applications

    International Nuclear Information System (INIS)

    Christou, K.; Louloudakis, D.; Vernardou, D.; Savvakis, C.; Katsarakis, N.; Koudoumas, E.; Kiriakidis, G.

    2015-01-01

    Hydrothermally grown tungsten trioxide coatings were prepared at 95 °C using different metal sulfates. Morphology of the oxides was altered from grains to flower- and urchin-like structures using potassium sulfate, sodium sulfate and lithium sulfate, respectively. The flower-like structures presented the highest deintercalated charge, 35 mC cm"−"2 with time response of 96 s. In addition, they indicated a charge transfer resistance across the tungsten trioxide–electrolyte interface of 752 Ω. These outcomes imply that they are promising candidates for electroactive applications. - Highlights: • Hydrothermally grown WO_3 coatings with controlled properties. • The choice of metal sulfate is important in determining their properties. • Flower-like hexagonal WO_3 structures for electroactive applications.

  8. AC conductivity and dielectric properties of bulk tungsten trioxide (WO3)

    Science.gov (United States)

    El-Nahass, M. M.; Ali, H. A. M.; Saadeldin, M.; Zaghllol, M.

    2012-11-01

    AC conductivity and dielectric properties of tungsten trioxide (WO3) in a pellet form were studied in the frequency range from 42 Hz to 5 MHz with a variation of temperature in the range from 303 K to 463 K. AC conductivity, σac(ω) was found to be a function of ωs where ω is the angular frequency and s is the frequency exponent. The values of s were found to be less than unity and decrease with increasing temperature, which supports the correlated barrier hopping mechanism (CBH) as the dominant mechanism for the conduction in WO3. The dielectric constant (ε‧) and dielectric loss (ε″) were measured. The Cole-Cole diagram determined complex impedance for different temperatures.

  9. Electronic properties of CdWO{sub 4}: Use of hybrid exchange and correlation functionals

    Energy Technology Data Exchange (ETDEWEB)

    Meena, B. S., E-mail: bsmphysics@gmail.com; Mund, H. S.; Ahuja, B. L. [Department of Physics, University College of Science, M. L. Sukhadia University, Udaipur-313001 (India); Heda, N. L. [Department of Pure and Applied Physics, University of Kota, Kota-324010 (India)

    2016-05-23

    Energy bands, density of states (DOS), Mulliken population (MP) and electron momentum densities (EMDs) of CdWO{sub 4} are presented using hybrid exchange and correlation functionals namely B3LYP, B3PW and PBE0. To validate the present hybrid potentials, theoretical EMDs have been compared with the experimental Compton profile. It is found that LCAO-B3LYP based Compton profile gives a better agreement with experiment than other theoretical profiles. The energy bands and DOS show a wide band gap semiconducting nature of CdWO{sub 4}. The theoretical band gap obtained using B3LYP scheme reconciles well with the available experimental data. In addition, we have also presented the anisotropies in EMDs along [100], [110] and [001] directions and the bonding effects using the MP data.

  10. Synthesis and characterization of WO3 nanostructures prepared by an aged-hydrothermal method

    International Nuclear Information System (INIS)

    Huirache-Acuna, R.; Paraguay-Delgado, F.; Albiter, M.A.; Lara-Romero, J.; Martinez-Sanchez, R.

    2009-01-01

    Nanostructures of tungsten trioxide (WO 3 ) have been successfully synthesized by using an aged route at low temperature (60 deg. C) followed by a hydrothermal method at 200 deg. C for 48 h under well controlled conditions. The material was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Specific Surface Area (S BET ) were measured by using the BET method. The lengths of the WO 3 nanostructures obtained are between 30 and 200 nm and their diameters are from 20 to 70 nm. The growth direction of the tungsten oxide nanostructures was determined along [010] axis with an inter-planar distance of 0.38 nm.

  11. Facile Preparation of Porous WO3 Film for Photoelectrochemical Splitting of Natural Seawater

    Science.gov (United States)

    Shi, Yonghong; Li, Yuangang; Wei, Xiaoliang; Feng, Juan; Li, Huajing; Zhou, Wanyi

    2017-12-01

    Sunlight-driven natural seawater splitting provides a promising way for large-scale conversion and storage of solar energy. Here, we develop a facile and low-cost method via a deposition-annealing technique to fabricate porous WO3 film and demonstrate its application as a photoanode for natural seawater splitting. The WO3 film yields a photocurrent density of 1.95 mA cm-2 and possesses excellent stability at 1.23 V (versus RHE), under the illumination of 100 mW cm-2 (AM 1.5G). The photoelectrochemical performance is ascribed to the large surface area and good permeation of the electrolyte into the porous film. Furthermore, the photocurrent density remains almost the same during 3 h continuous light irradiation. The evolution of chlorine gas from seawater splitting was determined with qualitative and quantitative analyses, with a Faradic efficiency of about 56%.

  12. Electronic structure calculation of Sr2CoWO6 double perovskite using DFT+U

    Science.gov (United States)

    Mandal, Golak; Jha, Dhiraj; Himanshu, A. K.; Ray, Rajyavardhan; Mukherjee, P.; Das, Nisith; Singh, B. K.; Sreenivas, K.; Singh, M. N.; Sinha, A. K.

    2018-04-01

    Using the synchrotron and Raman spectroscopy we measured the lattice parameter and Raman modes of the half-metallic (HM) Sr2CoWO6 (SCoW) synthesied by the solid state reaction technique.. The physical properties of SCoW are studies within the framework of density function theory (DFT) under the generalised gradient approximation (GGA) of Perdew, Bruke, and Ernzerhof both by itself and including a coulomb repulsion via the Hubbard approach or GGA+U. Our results states that Sr2CoWO6 material behaves as insulators for the spin-up orientation and spindown orientation as found for the half metallic systems and at U = 0.06eV the ground state of spin up channel being insulating with spin gap of 2.27eV comparable to the experimental Band gap (BG).

  13. Blue luminescence in Tm3+-doped KGd(WO4)2 single crystals

    International Nuclear Information System (INIS)

    Gueell, F.; Mateos, X.; Gavalda, Jna.; Sole, R.; Aguilo, M.; Diaz, F.; Massons, J.

    2004-01-01

    Up-conversion blue emissions of trivalent thulium ions in monoclinic KGd(WO 4 ) 2 single crystals at 454 and 479 nm are reported for a single pump laser source at 688 nm. We grew thulium-doped KGd(WO 4 ) 2 single crystals at several concentrations from 0.1% to 10%. We recorded a polarized optical absorption spectrum for the 3 F 2 + 3 F 3 energy levels of thulium at room temperature and low temperature (6 K). From the low temperature emission spectra we determined the splitting of the 3 H 6 ground state. The blue emissions are characterized as a function of the dopant concentration and temperature from 10 K to room temperature. To our knowledge, this is the first time that sequential two-photon excitation process (STEP) generated blue emissions in thulium-doped single crystals with a single excitation wavelength

  14. Ambient template synthesis of multiferroic MnWO4 nanowires and nanowire arrays

    International Nuclear Information System (INIS)

    Zhou Hongjun; Yiu Yuen; Aronson, M.C.; Wong, Stanislaus S.

    2008-01-01

    The current report describes the systematic synthesis of polycrystalline, multiferroic MnWO 4 nanowires and nanowire arrays with controllable chemical composition and morphology, using a modified template-directed methodology under ambient room-temperature conditions. We were able to synthesize nanowires measuring 55±10, 100±20, and 260±40 nm in diameter, respectively, with lengths ranging in the microns. Extensive characterization of as-prepared samples has been performed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and energy-dispersive X-ray spectroscopy. Magnetic behavior in these systems was also probed. - Graphical abstract: Systematic synthesis of crystalline, multiferroic MnWO4 nanowires and nanowire arrays with controllable chemical composition and morphology, using a modified template-directed methodology under ambient room-temperature conditions

  15. Synthesis and Characterization of WO3/Graphene Nanocomposites for Enhanced Photocatalytic Activities by One-Step In-Situ Hydrothermal Reaction

    Directory of Open Access Journals (Sweden)

    Xiaoxiao Hu

    2018-01-01

    Full Text Available Tungsten trioxide (WO3 nanorods are synthesized on the surface of graphene (GR sheets by using a one-step in-situ hydrothermal method employing sodium tungstate (Na2WO4·2H2O and graphene oxide (GO as precursors. The resulting WO3/GR nanocomposites are characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. The results confirm that the interface between WO3 nanorod and graphene contains chemical bonds. The enhanced optical absorption properties are measured by UV-vis diffuse reflectance spectra. The photocatalytic activity of the WO3/GR nanocomposites under visible light is evaluated by the photodegradation of methylene blue, where the degradation rate of WO3/GR nanocomposites is shown to be double that of pure WO3. This is attributed to the synergistic effect of graphene and the WO3 nanorod, which greatly enhances the photocatalytic performance of the prepared sample, reduces the recombination of the photogenerated electron-hole pairs and increases the visible light absorption efficiency. Finally, the photocatalytic mechanism of the WO3/GR nanocomposites is presented. The synthesis of the prepared sample is convenient, direct and environmentally friendly. The study reports a highly efficient composite photocatalyst for the degradation of contaminants that can be applied to cleaning up the environment.

  16. Radiation hardness qualification of PbWO4 scintillation crystals for the CMS Electromagnetic Calorimeter

    CERN Document Server

    Adzic, P.; Andelin, D.; Anicin, I.; Antunovic, Z.; Arcidiacono, R.; Arenton, M.W.; Auffray, E.; Argiro, S.; Askew, A.; Baccaro, S.; Baffioni, S.; Balazs, M.; Bandurin, D.; Barney, D.; Barone, L.M.; Bartoloni, A.; Baty, C.; Beauceron, S.; Bell, K.W.; Bernet, C.; Besancon, M.; Betev, B.; Beuselinck, R.; Biino, C.; Blaha, J.; Bloch, P.; Borisevitch, A.; Bornheim, A.; Bourotte, J.; Brown, R.M.; Buehler, M.; Busson, P.; Camanzi, B.; Camporesi, T.; Cartiglia, N.; Cavallari, F.; Cecilia, A.; Chang, P.; Chang, Y.H.; Charlot, C.; Chen, E.A.; Chen, W.T.; Chen, Z.; Chipaux, R.; Choudhary, B.C.; Choudhury, R.K.; Cockerill, D.J.A.; Conetti, S.; Cooper, S.I.; Cossutti, F.; Cox, B.; Cussans, D.G.; Dafinei, I.; Da Silva Di Calafiori, D.R.; Daskalakis, G.; David, A.; Deiters, K.; Dejardin, M.; De Benedetti, A.; Della Ricca, G.; Del Re, D.; Denegri, D.; Depasse, P.; Descamps, J.; Diemoz, M.; Di Marco, E.; Dissertori, G.; Dittmar, M.; Djambazov, L.; Djordjevic, M.; Dobrzynski, L.; Dolgopolov, A.; Drndarevic, S.; Drobychev, G.; Dutta, D.; Dzelalija, M.; Elliott-Peisert, A.; El Mamouni, H.; Evangelou, I.; Fabbro, B.; Faure, J.L.; Fay, J.; Fedorov, A.; Ferri, F.; Franci, D.; Franzoni, G.; Freudenreich, K.; Funk, W.; Ganjour, S.; Gascon, S.; Gataullin, M.; Gentit, F.X.; Ghezzi, A.; Givernaud, A.; Gninenko, S.; Go, A.; Gobbo, B.; Godinovic, N.; Golubev, N.; Govoni, P.; Grant, N.; Gras, P.; Haguenauer, M.; Hamel de Monchenault, G.; Hansen, M.; Haupt, J.; Heath, H.F.; Heltsley, B.; Cornell U., LNS.; Hintz, W.; Hirosky, R.; Hobson, P.R.; Honma, A.; Hou, G.W.S.; Hsiung, Y.; Huhtinen, M.; Ille, B.; Ingram, Q.; Inyakin, A.; Jarry, P.; Jessop, C.; Jovanovic, D.; Kaadze, K.; Kachanov, V.; Kailas, S.; Kataria, S.K.; Kennedy, B.W.; Kokkas, P.; Kolberg, T.; Korjik, M.; Krasnikov, N.; Krpic, D.; Kubota, Y.; Kuo, C.M.; Kyberd, P.; Kyriakis, A.; Lebeau, M.; Lecomte, P.; Lecoq, P.; Ledovskoy, A.; Lethuillier, M.; Lin, S.W.; Lin, W.; Litvine, V.; Locci, E.; Longo, E.; Loukas, D.; Luckey, P.D.; Lustermann, W.; Ma, Y.; Malberti, M.; Malcles, J.; Maletic, D.; Manthos, N.; Maravin, Y.; Marchica, C.; Marinelli, N.; Markou, A.; Markou, C.; Marone, M.; Matveev, V.; Mavrommatis, C.; Meridiani, P.; Milenovic, P.; Mine, P.; Missevitch, O.; Mohanty, A.K.; Moortgat, F.; Musella, P.; Musienko, Y.; Nardulli, A.; Nash, J.; Nedelec, P.; Negri, P.; Newman, H.B.; Nikitenko, A.; Nessi-Tedaldi, F.; Obertino, M.M.; Organtini, G.; Orimoto, T.; Paganoni, M.; Paganini, P.; Palma, A.; Pant, L.; Papadakis, A.; Papadakis, I.; Papadopoulos, I.; Paramatti, R.; Parracho, P.; Pastrone, N.; Patterson, J.R.; Pauss, F.; Peigneux, J.P.; Petrakou, E.; Phillips, D.G.; Piroue, P.; Ptochos, F.; Puljak, I.; Pullia, A.; Punz, T.; Puzovic, J.; Ragazzi, S.; Rahatlou, S.; Rander, J.; Razis, P.A.; Redaelli, N.; Renker, D.; Reucroft, S.; Ribeiro, P.; Rogan, C.; Ronquest, M.; Rosowsky, A.; Rovelli, C.; Rumerio, P.; Rusack, R.; Rusakov, S.V.; Ryan, M.J.; Sala, L.; Salerno, R.; Schneegans, M.; Seez, C.; Sharp, P.; Shepherd-Themistocleous, C.H.; Shiu, J.G.; Shivpuri, R.K.; Shukla, P.; Siamitros, C.; Sillou, D.; Silva, J.; Silva, P.; Singovsky, A.; Sirois, Y.; Sirunyan, A.; Smith, V.J.; Stockli, F.; Swain, J.; Tabarelli de Fatis, T.; Takahashi, M.; Tancini, V.; Teller, O.; Theofilatos, K.; Thiebaux, C.; Timciuc, V.; Timlin, C.; Titov, Maxim P.; Topkar, A.; Triantis, F.A.; Troshin, S.; Tyurin, N.; Ueno, K.; Uzunian, A.; Varela, J.; Verrecchia, P.; Veverka, J.; Virdee, T.; Wang, M.; Wardrope, D.; Weber, M.; Weng, J.; Williams, J.H.; Yang, Y.; Yaselli, I.; Yohay, R.; Zabi, A.; Zelepoukine, S.; Zhang, J.; Zhang, L.Y.; Zhu, K.; Zhu, R.Y.

    2010-01-01

    Ensuring the radiation hardness of PbWO4 crystals was one of the main priorities during the construction of the electromagnetic calorimeter of the CMS experiment at CERN. The production on an industrial scale of radiation hard crystals and their certification over a period of several years represented a difficult challenge both for CMS and for the crystal suppliers. The present article reviews the related scientific and technological problems encountered.

  17. Luminescence and energy transfer mechanisms in CaWO{sub 4} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Spassky, D., E-mail: deris2002@mail.ru [Skobeltsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Vorob' evy Gory, 119991 Moscow (Russian Federation); Mikhailin, V. [Skobeltsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Vorob' evy Gory, 119991 Moscow (Russian Federation); Nazarov, M. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Institute of Applied Physics, Academiei Street 5, Chisinau MD-2028 (Moldova, Republic of); Ahmad-Fauzi, M.N. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Zhbanov, A. [Department of Medical System Engineering, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of)

    2012-10-15

    The processes of the excitation energy transfer to the emission centers have been investigated for calcium tungstate crystals taking into account features of the electronic structure of valence band and conduction band. The calculations of the electronic structure of host lattice CaWO{sub 4} were performed in the framework of density functional theory. The underestimation of the bandgap value in the calculations has been corrected according to the experimental data. Luminescence of two samples grown using Czochralski (cz) and hydrothermal (ht) techniques were studied. Intrinsic emission band related to excitons, self-trapped on WO{sub 4} complexes has been observed for the both samples while the additional low-energy emission band related to the defects of crystal structure has been observed only for (ht) sample indicating the enhanced concentration of the defects in the sample. It was shown that the features of the conduction band electronic structure are reproduced in the excitation spectrum of intrinsic luminescence only for the (ht) sample while for (cz) sample the correlation is absent. The enhanced role of the competitive channels in the process of excitation energy transfer to intrinsic emission centers in (ht) sample is responsible for the observed difference. - Highlights: Black-Right-Pointing-Pointer The band structure of CaWO{sub 4} was calculated in the framework of DFT LAPW method. Black-Right-Pointing-Pointer Calculation results were validated via joint analysis with experimental data. Black-Right-Pointing-Pointer The bandgap E{sub g} of CaWO{sub 4} was determined as 4.90{+-}0.15 eV. Black-Right-Pointing-Pointer The correlation between the band structure and excitation spectrum is demonstrated. Black-Right-Pointing-Pointer Influence of competitive relaxation channel on energy transfer to STE is shown.

  18. Optical spectroscopy of Ho{sup 3+}-doped SrWO{sub 4} scheelite crystal

    Energy Technology Data Exchange (ETDEWEB)

    Li Jianfu; Jia Guohua; Zhu Zhaojie; You Zhenyu; Wang Yan; Wu Baichang; Tu Chaoyang [Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, State Key Laboratory of Structural Chemistry and National Engineering Research Center for Optoelectronic Crystalline Materials, Fuzhou, Fujian 350002 (China)

    2007-04-07

    Ho{sup 3+}-doped SrWO{sub 4} crystal was grown by the Czochralski method. The polarized absorption and emission spectra together with the fluorescent decay curve were measured at room temperature. The intensity parameters, radiative lifetimes and branching ratios were calculated based on the Judd-Ofelt theory. The stimulated emission cross-sections of the potential laser transitions were determined using the reciprocity method.

  19. Influence of Mo impurity on the spectroscopic and scintillation properties of PbWO4 crystals

    International Nuclear Information System (INIS)

    Boehm, M.; Hofstaetter, A.; Luh, M.; Meyer, B.K.; Scharmann, A.; Drobychev, G.Yu.; Grenoble-1 Univ., 74 - Annecy; Peigneux, J.P.

    1997-12-01

    The influence of molybdenum doping on the spectroscopic and scintillation properties of lead tungstate crystals has been investigated. From the results the slow scintillation component as well as the afterglow are found to be due to the Mo impurity. In addition the blue luminescence from excited (WO 4 ) 2- -complex seems to be increasingly suppressed as the doping concentration goes on. Possible mechanisms for the effects have been discussed. (author)

  20. Effect of SiO2 Overlayer on WO3 Sensitivity to Ammonia

    Directory of Open Access Journals (Sweden)

    Vibha Srivastava

    2010-06-01

    Full Text Available Ammonia gas sensing properties of tungsten trioxide thick film sensor was investigated. The doping of noble catalysts such as Pt, Pd, Au enhanced the gas sensitivity. Platinum doping was found to result in highest sensitivity. Remarkable sensitivity enhancement was realized by coating WO3 thick film sensors with SiO2 overlayer. Sol gel process derived silica overlayer increased ammonia gas sensitivity for doped as well as undoped sensor.

  1. Preparation of ultra-thin and high-quality WO{sub 3} compact layers and comparision of WO{sub 3} and TiO{sub 2} compact layer thickness in planar perovskite solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jincheng; Shi, Chengwu, E-mail: shicw506@foxmail.com; Chen, Junjun; Wang, Yanqing; Li, Mingqian

    2016-06-15

    In this paper, the ultra-thin and high-quality WO{sub 3} compact layers were successfully prepared by spin-coating-pyrolysis method using the tungsten isopropoxide solution in isopropanol. The influence of WO{sub 3} and TiO{sub 2} compact layer thickness on the photovoltaic performance of planar perovskite solar cells was systematically compared, and the interface charge transfer and recombination in planar perovskite solar cells with TiO{sub 2} compact layer was analyzed by electrochemical impedance spectroscopy. The results revealed that the optimum thickness of WO{sub 3} and TiO{sub 2} compact layer was 15 nm and 60 nm. The planar perovskite solar cell with 15 nm WO{sub 3} compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO{sub 2} compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency. - Graphical abstract: The planar perovskite solar cell with 15 nm WO{sub 3} compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO{sub 2} compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency. Display Omitted - Highlights: • Preparation of ultra-thin and high-quality WO{sub 3} compact layers. • Perovskite solar cell with 15 nm-thick WO{sub 3} compact layer achieved PCE of 10.14%. • Perovskite solar cell with 60 nm-thick TiO{sub 2} compact layer achieved PCE of 12.64%.

  2. First-order character of the displacive structural transition in BaWO4

    International Nuclear Information System (INIS)

    Tan Da-Yong; Xiao Wan-Sheng; Zhou Wei; Chen Ming; Xiong Xiao-Lin; Song Mao-Shuang

    2012-01-01

    Nearly all displacive transitions have been considered to be continuous or second order, and the rigid unit mode (RUM) provides a natural candidate for the soft mode. However, in-situ X-ray diffraction and Raman measurements show clearly the first-order evidences for the scheelite-to-fergusonite displacive transition in BaWO 4 : a 1.6% volume collapse, coexistence of phases, and hysteresis on release of pressure. Such first-order signatures are found to be the same as the soft modes in BaWO 4 , which indicates the scheelite-to-fergusonite displacive phase transition hides a deeper physical mechanism. By the refinement of atomic displacement parameters, we further show that the first-order character of this phase transition stems from a coupling of large compression of soft BaO 8 polyhedrons to the small displacive distortion of rigid WO 4 tetrahedrons. Such a coupling will lead to a deeper physical insight in the phase transition of the common scheelite-structured compounds. (condensed matter: structural, mechanical, and thermal properties)

  3. Development of w/o microemulsion for transdermal delivery of iodide ions.

    Science.gov (United States)

    Lou, Hao; Qiu, Ni; Crill, Catherine; Helms, Richard; Almoazen, Hassan

    2013-03-01

    The objective of this study was to develop a water-in-oil (w/o) microemulsion which can be utilized as a transdermal delivery for iodide ions. Several w/o microemulsion formulations were prepared utilizing Span 20, ethanol, Capryol 90®, and water. The selected formulations had 5%, 10%, 15%, 20%, and a maximum of 23% w/w water content. Potassium iodide (KI) was incorporated in all formulations at 5% w/v. Physicochemical characterizations were conducted to evaluate the structure and stability. These studies included: mean droplet size, pH, viscosity, conductivity, and chemical stability tests. In vitro human skin permeation studies were conducted to evaluate the diffusion of the iodide ion through human skin. The w/o microemulsion formulations were stable and compatible with iodide ions with water content ranging from 5% to 23% w/w. The addition of KI influenced the physicochemical properties of microemulsion as compared to blank microemulsion formulations. In vitro human skin permeation studies indicated that selected formulations improved iodide ion diffusion significantly as compared to control (KI solution; P valuemicroemulsion. Span 20, ethanol and Capryol 90 protected the iodide ions against oxidation and formed a stable microemulsion. It is worth to note that according to Hofmeister series, iodide ions tend to lower the interfacial tension between water and oil and consequently enhance overall stability. This work illustrates that microemulsion system can be utilized as a vehicle for the transdermal administration of iodide.

  4. Hydrogenation of carbon monoxide on WO/sub 3/-Supported ruthenium catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Yoshinari, Tomohiro; Suganuma, Fujio; Sera, Chikara

    1988-01-01

    In this study, a WO/sub 3/-supported catalyst was prepared to conduct hydrogenation of CO for examining the product distribution and composition of hydrocarbons, using a gamma-alumina-supported catalyst for comparison. These catalysts were used under pressure to conduct a distributive reaction and the desorbing behavior of CO or H/sub 2/ at elevated temperature was measured to examine the influence of the type of carrier or the method of preparation on the activity and the distribution of products formed. The WO/sub 3/-supported catalyst gave a carbon chain length distribution that did not comply with the rule of Schulz-Flory, giving a composition richer in the isomers. Carbon number distribution is affected by Ru-dispersion, and the selectivity of isomers depends on the acidity of the carrier. Formed products distribution of the WO/sub 3/-supported reaction is attributable to the secondary reaction, which relates to the acidic point of the carrier, of the primary product formed on the metal. (7 figs, 4 tabs, 18 refs)

  5. Silver loaded WO{sub 3-x}/TiO{sub 2} composite multifunctional thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dunnill, Charles W.; Noimark, Sacha; Parkin, Ivan P., E-mail: I.P.Parkin@ucl.ac.uk

    2012-06-30

    Multifunctional WO{sub 3-x}-TiO{sub 2} composite thin films have been prepared by sol-gel synthesis and shown to be good visible light photocatalysts whilst retaining a desirable underlying blue colouration. The WO{sub 3-x}-TiO{sub 2} composite thin films were further enhanced using silver nanoparticles synthesised in-situ on the surface from the photo-degradation of silver nitrate solution. Thin films were characterised using X-ray diffraction, Raman, Scanning electron microscopy and UV-visible spectroscopy and shown to photo degrade stearic acid, using white light {lambda} = 420-800 nm. - Highlights: Black-Right-Pointing-Pointer WO{sub 3-X} TiO{sub 2} composite thin films were synthesised by sol-gel methods. Black-Right-Pointing-Pointer Blue tinted glass is desirable for the value added glass industry. Black-Right-Pointing-Pointer Silver nanoparticle island formation enhances the activity of the films. Black-Right-Pointing-Pointer Blue tinted 'value added' coated glass is now possible.

  6. Identifying Sources of Scientific Knowledge: classifying non-source items in the WoS

    Energy Technology Data Exchange (ETDEWEB)

    Calero-Medina, C.M.

    2016-07-01

    The sources of scientific knowledge can be tracked using the references in scientific publications. For instance, the publications from the scientific journals covered by the Web of Science database (WoS) contain references to publications for which an indexed source record exist in the WoS (source items) or to references for which an indexed source record does not exist in the WoS (non-source items). The classification of the non-source items is the main objective of the work in progress presented here. Some other scholars have classified and identified non-source items with different purposes (e.g. Butler & Visser (2006); Liseé, Larivière & Archambault (2008); Nerderhof, van Leeuwen & van Raan (2010); Hicks & Wang (2013); Boyack & Klavans (2014)). But these studies are focused in specific source types, fields or set of papers. The work presented here is much broader in terms of the number of publications, source types and fields. (Author)

  7. TiO_2/WO_3 photoactive bilayers in the UV-Vis light region

    International Nuclear Information System (INIS)

    Vasilaki, E.; Vernardou, D.; Kenanakis, G.; Katsarakis, N.; Vamvakaki, M.

    2017-01-01

    In this work, photoactive bilayered films consisting of anatase TiO_2 and monoclinic WO_3 were synthesized by a sol-gel route. Titanium isopropoxide and tungsten hexachloride were used as metal precursors and deposition was achieved by spin-coating on Corning glass substrates. The samples were characterized by X-ray diffraction, photoluminescence, UV-Vis, and Raman spectroscopy, as well as field emission scanning electron microscopy. The prepared immobilized catalysts were tested for their photocatalytic performance by the decolorization of methylene blue in aqueous matrices, under UV-Vis light irradiation. The annealing process influenced the crystallinity of the bilayered films, while the concentration of the tungsten precursor solution and the position of the tungsten trioxide layer further affected their photocatalytic performance. In particular, the photocatalytic performance of the bilayered films was optimized at a concentration of 0.1 M of the WO_3 precursor solution, when deposited as an overlying layer on TiO_2 by two annealing steps (∝76% methylene blue decolorization in 300 min of irradiation versus ∝59% in the case of a bare TiO_2 film). In general, the coupled layer catalysts exhibited superior photoactivity compared to that of bare TiO_2 films with WO_3 acting as an electron trap, resulting, therefore, in a more efficient electron-hole separation and inhibiting their recombination. (orig.)

  8. Gas Sensor Based on 3-D WO3 Inverse Opal: Design and Applications

    Directory of Open Access Journals (Sweden)

    Ruiqing Xing

    2017-03-01

    Full Text Available A three-dimensional inverse opal (3DIO WO3 architecture has been synthesized via a simple sacrificial template method. Morphology features of the 3DIO were characterized by scanning electron microscope (SEM and its structure was characterized by X-ray diffraction (XRD. The shrinking ratio of the PMMA spheres was ~28.2% through measuring the distribution of the PMMA spheres and 3DIO WO3 center-to-center distance between the spheres and macropores, respectively. Beyond that, the 3DIO gas sensing properties were investigated systematically and the sensing mechanism of 3DIO WO3 was proposed. The results indicated that the response of the 3DIO sensor possessed excellent sensitivity to acetone gas, especially at trace levels. The 3DIO gas sensor response was ~7 to 5 ppm of acetone and could detect acetone low to 0.2 ppm effectively, which was in close proximity to the theoretical low detection limit of 0.14 ppm when Ra/Rg ≥ 1.2 was used as the criterion for reliable gas sensing. All in all, the obvious satisfaction of the gas-sensing properties was ascribed to the structure of the 3DIO, and the sensor could be a promising novel device in the future.

  9. Understanding the conductive channel evolution in Na:WO(3-x)-based planar devices.

    Science.gov (United States)

    Shang, Dashan; Li, Peining; Wang, Tao; Carria, Egidio; Sun, Jirong; Shen, Baogen; Taubner, Thomas; Valov, Ilia; Waser, Rainer; Wuttig, Matthias

    2015-04-14

    An ion migration process in a solid electrolyte is important for ion-based functional devices, such as fuel cells, batteries, electrochromics, gas sensors, and resistive switching systems. In this study, a planar sandwich structure is prepared by depositing tungsten oxide (WO(3-x)) films on a soda-lime glass substrate, from which Na(+) diffuses into the WO(3-x) films during the deposition. The entire process of Na(+) migration driven by an alternating electric field is visualized in the Na-doped WO(3-x) films in the form of conductive channel by in situ optical imaging combined with infrared spectroscopy and near-field imaging techniques. A reversible change of geometry between a parabolic and a bar channel is observed with the resistance change of the devices. The peculiar channel evolution is interpreted by a thermal-stress-induced mechanical deformation of the films and an asymmetric Na(+) mobility between the parabolic and the bar channels. These results exemplify a typical ion migration process driven by an alternating electric field in a solid electrolyte with a low ion mobility and are expected to be beneficial to improve the controllability of the ion migration in ion-based functional devices, such as resistive switching devices.

  10. N, Fe and WO3 modified TiO2 for degradation of formaldehyde

    International Nuclear Information System (INIS)

    Tong Haixia; Zhao Li; Li Dan; Zhang Xiongfei

    2011-01-01

    Graphical abstract: The undoped TiO 2 powder (T(0)) shows strong photoabsorption only at wavelengths shorter than 400 nm, and while Fe 3+ and N-doped TiO 2 nanoparticles show photoabsorption in visible region and the absorption edge shifts to a longer wavelength. WO 3 compounding also benefits the photoabsorption in visible region. Display Omitted Highlights: → The preparation of the catalysts co-doped by Fe, N and compounded by WO 3 . → The obvious sculptured 'pattern' of the catalysts doped by Fe in the SEM images. → Strengthened photoabsorption to visible light of the modified catalysts from UV-DRS analysis. - Abstract: Butyltitanate, ethanol and glacial acetic acid were chosen as titanium source, solvent and chelating agent, respectively, via a sol-gel method combined impregnation method to prepare N, Fe co-doped and WO 3 compounded photocatalyst TiO 2 powder. The synthesized products were characterized by X-ray diffraction (XRD), diffuse reflectance UV-Vis spectra (UV-DRS), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Photocatalytic degradation of formaldehyde was employed to investigate the catalytic activity. The results show that the degradation rate is 77.61% in 180 min under UV light irradiation when the concentration of N is fixed on, and the optimum proportioning ratio of n(Fe):n(W):n(Ti) is 0.5:2:100.

  11. Silver loaded WO3−x/TiO2 composite multifunctional thin films

    International Nuclear Information System (INIS)

    Dunnill, Charles W.; Noimark, Sacha; Parkin, Ivan P.

    2012-01-01

    Multifunctional WO 3−x –TiO 2 composite thin films have been prepared by sol–gel synthesis and shown to be good visible light photocatalysts whilst retaining a desirable underlying blue colouration. The WO 3−x –TiO 2 composite thin films were further enhanced using silver nanoparticles synthesised in-situ on the surface from the photo-degradation of silver nitrate solution. Thin films were characterised using X-ray diffraction, Raman, Scanning electron microscopy and UV–visible spectroscopy and shown to photo degrade stearic acid, using white light λ = 420–800 nm. - Highlights: ► WO 3−X TiO 2 composite thin films were synthesised by sol–gel methods. ► Blue tinted glass is desirable for the value added glass industry. ► Silver nanoparticle island formation enhances the activity of the films. ► Blue tinted “value added” coated glass is now possible.

  12. The spectroscopy investigation of ZnWO{sub 4}:Tm{sup 3+} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Yang Fugui, E-mail: ruopiao@fjirsm.ac.cn [Department of Electronic Information Science, Fujian Jiangxia University, Fuzhou, Fujian 350108 (China); Tu Chaoyang [Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer The spectroscopy and refractive index of single crystal ZnWO{sub 4}:Tm{sup 3+} are investigated systematically. Black-Right-Pointing-Pointer The Judd-Ofelt parameters are obtained. Black-Right-Pointing-Pointer The gain cross sections at {approx}2 {mu}m are estimated by reciprocity method (RM). Black-Right-Pointing-Pointer The laser operation at {approx}2 {mu}m is discussed. - Abstract: The single crystal ZnWO{sub 4}:Tm{sup 3+} has been grown by Czochralski method. The XRD, refractive index, absorption and fluorescence spectra are measured. The Judd-Ofelt parameters{Omega}{sub 2}, {Omega}{sub 4}, {Omega}{sub 6} are obtained to be 6.3 Multiplication-Sign 10{sup -20}, 1.3 Multiplication-Sign 10{sup -20}, 1.4 Multiplication-Sign 10{sup -20} cm{sup 2}, respectively. The fluorescence decay time of the {sup 3}H{sub 4} level is measured to be 0.113 ms and the quantum efficiency is 57%. The gain cross sections corresponding to {sup 3}F{sub 4}{yields}{sup 3}H{sub 6} transition at {approx}2 {mu}m are estimated by the reciprocity method (RM). The strong gain at {approx}2 {mu}m indicates that the ZnWO{sub 4}:Tm{sup 3+} crystal is a promising laser host for {approx}2 {mu}m laser.

  13. High-pressure phases in the system W-O. Pt. 2

    International Nuclear Information System (INIS)

    Barabanenkov, Yu.A.; Zakharov, N.D.; Zibrov, I.P.; Filonenko, V.P.; Werner, P.; Popov, A.I.; Valkovskii, M.D.

    1993-01-01

    A new type of tungsten oxide has been synthesized from a mixture of W and WO 3 by a solid-phase sintering method under high-pressure conditions. The crystal structure of the new oxide was investigated by HRTEM, selected-area electron diffraction and X-ray powder diffraction. The structure belongs to space group Pbam or P2 1 2 1 2 and has the following unit-cell parameters: a=21.431(9), b=17.766(7), c=3.783(2) A, V=1440 A 3 , Z=32, D x =8.33 g cm -3 . The structural model and W-cation positions were determined by HRTEM and image processing. X-ray powder analysis and the SHELX computer program were used to prove the proposed structural model: N=158, R=0.075, U iso (W)=0.019(3), U iso (O)=0.055(12) A 2 . The investigated crystal structure is, in fact, similar to WO 2.72 and is formed by W-O octahedra and pentagonal bipyramids. (orig.)

  14. Effects of surface properties of (010), (001) and (100) of MnWO4 and FeWO4 on absorption of collector

    International Nuclear Information System (INIS)

    Qiu, X.Y.; Huang, H.W.; Gao, Y.D.

    2016-01-01

    Graphical abstract: - Highlights: • The (010) plane is the easiest one to be seen in wolframite, followed by (001) plane and (100) plane. • (010) and (001) are the primary planes for the absorption of anion collector ions. • W atom can be the absorption site in (001) plane but not in (010) plane. • The proportion of platy particles as well as their perfect cleavage planes increases with the decrease of particle size. • Cleavages occupied by W atom can lead to a low recovery when using BHA alone as the collector of wolframite. - Abstract: The atom distribution and electronic properties of (010), (001) and (100) planes of MnWO 4 and FeWO 4 were studied based on a DFT calculation. The surface stabilities of the three planes were compared according to their surface energies. The most stable one is (010) plane, followed by (001) and (100). (010) and (001) are the main planes for absorption of anion collector ions, which is supported by their bonding relationship and charge density distribution of surface atoms and finally proved by the results of flotation test and stereomicroscope analysis. In addition, the tungsten atoms can be viewed as the absorption site for collectors in (001) plane but not in (010) plane, which can explain the phenomenon in flotation test that the recovery of wolframite can hardly be further boosted even with a high dosage of BHA.

  15. Effects of surface properties of (010), (001) and (100) of MnWO{sub 4} and FeWO{sub 4} on absorption of collector

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, X.Y. [School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, Hunan (China); Guangzhou Research Institute of Non-Ferrous Metals, Guangzhou 510651, Guangdong (China); Huang, H.W., E-mail: hhwknight@163.com [School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, Hunan (China); Guangzhou Research Institute of Non-Ferrous Metals, Guangzhou 510651, Guangdong (China); Gao, Y.D. [Guangzhou Research Institute of Non-Ferrous Metals, Guangzhou 510651, Guangdong (China)

    2016-03-30

    Graphical abstract: - Highlights: • The (010) plane is the easiest one to be seen in wolframite, followed by (001) plane and (100) plane. • (010) and (001) are the primary planes for the absorption of anion collector ions. • W atom can be the absorption site in (001) plane but not in (010) plane. • The proportion of platy particles as well as their perfect cleavage planes increases with the decrease of particle size. • Cleavages occupied by W atom can lead to a low recovery when using BHA alone as the collector of wolframite. - Abstract: The atom distribution and electronic properties of (010), (001) and (100) planes of MnWO{sub 4} and FeWO{sub 4} were studied based on a DFT calculation. The surface stabilities of the three planes were compared according to their surface energies. The most stable one is (010) plane, followed by (001) and (100). (010) and (001) are the main planes for absorption of anion collector ions, which is supported by their bonding relationship and charge density distribution of surface atoms and finally proved by the results of flotation test and stereomicroscope analysis. In addition, the tungsten atoms can be viewed as the absorption site for collectors in (001) plane but not in (010) plane, which can explain the phenomenon in flotation test that the recovery of wolframite can hardly be further boosted even with a high dosage of BHA.

  16. Electro-deposition metallic tungsten coatings in a Na{sub 2}WO{sub 4}-WO{sub 3} melt on copper based alloy substrate

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y.H., E-mail: dreamerhong77@126.com [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Zhang, Y.C.; Liu, Q.Z.; Li, X.L.; Jiang, F. [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer The tungsten coating (>1 mm) was obtained by electro-deposition method in molten salt. Black-Right-Pointing-Pointer Different thickness tungsten coatings were obtained by using different durations. Black-Right-Pointing-Pointer Good performance of coating was obtained when pulse parameters were modulated. - Abstract: The tungsten coating was prepared by electro-deposition technique on copper alloy substrate in a Na{sub 2}WO{sub 4}-WO{sub 3} melt. The coating's surface and cross-section morphologies as well as its impurities were investigated by XPS, SEM and line analysis. Various plating durations were investigated in order to obtain an optimal coating's thickness. The results demonstrated that the electro-deposited coating was compact, voidless, crackless and free from impurities. The tungsten coating's maximum Vickers hardness was measured to be 520 HV. The tungsten coating's minimum oxygen content was determined to be 0.018 wt%. Its maximum thickness was measured to be 1043.67 {mu}m when the duration of electrolysis was set to 100 h. The result of this study has demonstrated the feasibility of having thicker tungsten coatings on copper alloy substrates. These electrodeposited tungsten coatings can be potentially implemented as reliable armour for the medium heat flux plasma facing component (PFC).

  17. Evaluate humidity sensing properties of novel TiO{sub 2}–WO{sub 3} composite material

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Wang-De [Department of Applied Chemistry, Providence University, Taichung 43301 Taiwan, ROC (China); Department of Center for General Education, St. Mary' s Junior College of Medicine, Nursing and Management, Yilan 26644 Taiwan, ROC (China); Lai, De-Sheng; Chen, Min-Hung [Department of Applied Chemistry, Providence University, Taichung 43301 Taiwan, ROC (China); Wu, Ren-Jang, E-mail: rjwu@pu.edu.tw [Department of Applied Chemistry, Providence University, Taichung 43301 Taiwan, ROC (China); Chen, Fu-Chou [Department of Medical Research, Taichung Veterans General Hospital, Taichung 407, Taiwan, ROC (China)

    2013-10-15

    Graphical abstract: TiO{sub 2}–WO{sub 3} (1:1) showed better humidity sensing properties than others within the range of 12–90% relative humidity (RH), the response and recovery time were about 20 s and 160 s, respectively. Compared to the previous studies, the prepared sensor exhibits higher sensitivity (S = 451) and the low hysteresis value was around 0.13% at 32% RH. - Highlights: • Novel TiO{sub 2}–WO{sub 3} composite material was prepared for humidity sensor. • The sensor exhibits higher sensitivity (S = 451). • Low hysteresis value was around 0.13% at 32% RH. - Abstract: A novel TiO{sub 2}–WO{sub 3} composite material was prepared using a different proportion of TiO{sub 2} and WO{sub 3} to that investigated in previous studies. The obtained mesoporous material was characterized using X-ray diffraction, Fourier transform infrared spectrometry, transmission electron microscopy, energy dispersive X-ray spectroscopy, and N{sub 2} adsorption-desorption techniques. The humidity-sensing properties were measured using an inductance, capacitance and resistance analyzer. The results demonstrated that the TiO{sub 2}–WO{sub 3} sample with a ratio of 1:1 showed better humidity sensing properties. Compared to previous studies, the prepared sensor exhibited higher sensitivity (S = 451) and the lower hysteresis value was around 0.13% at 32% RH. Complex impedance analysis indicated that the enhanced humidity sensitivity was probably due to spherical Brunauer–Emmett–Teller surface area and the hetero-junction between TiO{sub 2}–WO{sub 3} thin films, while the impedance varied about three orders of magnitude. Our results demonstrated the potential application of TiO{sub 2}–WO{sub 3} composite for fabricating high performance humidity sensors.

  18. Enhanced photocatalytic activity of cadmium-doped Bi{sub 2}WO{sub 6} nanoparticles under simulated solar light

    Energy Technology Data Exchange (ETDEWEB)

    Song, Xu Chun, E-mail: songxuchunfj@163.com; Li, Wen Ting [Fujian Normal University, Department of Chemistry (China); Huang, Wan Zhen; Zhou, Huan [Zhejiang University of Technology, Research Center of Analysis and Measurement (China); Yin, Hao Yong [Hangzhou Dianzi University, Institute of Environmental Science and Engineering (China); Zheng, Yi Fan [Zhejiang University of Technology, Research Center of Analysis and Measurement (China)

    2015-03-15

    Novel cadmium-doped Bi{sub 2}WO{sub 6} nanoparticles with different Cd contents have been synthesized by a one-step route using ethylene glycol and water as solvents at 180 °C for 12 h. The as-synthesized samples were characterized in detailed by SEM, XRD, EDS, HRTEM, UV–Vis DRS, BET techniques, and so on. The results shown that with the increase of the Cd{sup 2+} addition, the crystal structure, lattice space, and absorption edge were not significantly changed and the calculated band gap value was 2.58 eV. However, the flower-like Bi{sub 2}WO{sub 6} sphere was gradually destroyed. Simultaneously, the surface area and photocurrent responses of the catalysts were greatly increased. Photocatalytic activity of the Cd-doped Bi{sub 2}WO{sub 6} samples was determined by monitoring the change of RhB concentration under simulated solar light. The results revealed that cadmium doping greatly improved the photocatalytic efficiency of Bi{sub 2}WO{sub 6}. The Bi{sub 2}WO{sub 6} sample with R{sub Cd} = 0.05 displayed the highest photocatalytic activity, and the degradation rate is about two times greater than pure Bi{sub 2}WO{sub 6}. Moreover, the Cd–Bi{sub 2}WO{sub 6} photocatalyst remained stable even after five consecutive cycles. A possible mechanism of photocatalytic activity enhancement on basis of the experimental results was proposed.

  19. A study of transition from n- to p-type based on hexagonal WO3 nanorods sensor

    Science.gov (United States)

    Wu, Ya-Qiao; Hu, Ming; Wei, Xiao-Ying

    2014-04-01

    Hexagonal WO3 nanorods are fabricated by a facile hydrothermal process at 180 °C using sodium tungstate and sodium chloride as starting materials. The morphology, structure, and composition of the prepared nanorods are studied by scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive spectroscopy. It is found that the agglomeration of the nanorods is strongly dependent on the PH value of the reaction solution. Uniform and isolated WO3 nanorods with diameters ranging from 100 nm-150 nm and lengths up to several micrometers are obtained at PH = 2.5 and the nanorods are identified as being hexagonal in phase structure. The sensing characteristics of the WO3 nanorod sensor are obtained by measuring the dynamic response to NO2 with concentrations in the range 0.5 ppm-5 ppm and at working temperatures in the range 25 °C-250 °C. The obtained WO3 nanorods sensors are found to exhibit opposite sensing behaviors, depending on the working temperature. When being exposed to oxidizing NO2 gas, the WO3 nanorod sensor behaves as an n-type semiconductor as expected when the working temperature is higher than 50 °C, whereas, it behaves as a p-type semiconductor below 50 °C. The origin of the n- to p-type transition is correlated with the formation of an inversion layer at the surface of the WO3 nanorod at room temperature. This finding is useful for making new room temperature NO2 sensors based on hexagonal WO3 nanorods.

  20. A study of transition from n- to p-type based on hexagonal WO3 nanorods sensor

    International Nuclear Information System (INIS)

    Wu Ya-Qiao; Hu Ming; Wei Xiao-Ying

    2014-01-01

    Hexagonal WO 3 nanorods are fabricated by a facile hydrothermal process at 180 °C using sodium tungstate and sodium chloride as starting materials. The morphology, structure, and composition of the prepared nanorods are studied by scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive spectroscopy. It is found that the agglomeration of the nanorods is strongly dependent on the PH value of the reaction solution. Uniform and isolated WO 3 nanorods with diameters ranging from 100 nm–150 nm and lengths up to several micrometers are obtained at PH = 2.5 and the nanorods are identified as being hexagonal in phase structure. The sensing characteristics of the WO 3 nanorod sensor are obtained by measuring the dynamic response to NO 2 with concentrations in the range 0.5 ppm–5 ppm and at working temperatures in the range 25 °C–250 °C. The obtained WO 3 nanorods sensors are found to exhibit opposite sensing behaviors, depending on the working temperature. When being exposed to oxidizing NO 2 gas, the WO 3 nanorod sensor behaves as an n-type semiconductor as expected when the working temperature is higher than 50 °C, whereas, it behaves as a p-type semiconductor below 50 °C. The origin of the n- to p-type transition is correlated with the formation of an inversion layer at the surface of the WO 3 nanorod at room temperature. This finding is useful for making new room temperature NO 2 sensors based on hexagonal WO 3 nanorods. (general)

  1. Preparation and characterization of zinc and copper co-doped WO3 nanoparticles: Application in photocatalysis and photobiology.

    Science.gov (United States)

    Mohammadi, Sanaz; Sohrabi, Maryam; Golikand, Ahmad Nozad; Fakhri, Ali

    2016-08-01

    In this study, pure, Zn, Cu, Zn,Cu co-doped WO3 nanoparticles samples were prepared by precipitation and co-precipitation methods. These nanoparticles were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDX), Dynamic light scattering (DLS), UV-visible and photoluminescence (PL) spectroscopy. The synthesized pure, Zn, Cu, Zn,Cu co-doped WO3 nanoparticles have smart optical properties and average sizes with 3.2, 3.12, 3.08 and 2.97eV of band-gap, 18.1, 23.2, 25.7 and 30.2nm, respectively. Photocatalytic activity of four nanoparticles was studying towards degradation of gentamicin antibiotic under ultraviolet and visible light irradiation. The result showed that Zn,Cu co-doped WO3 possessed high photocatalytic activity. The photocatalytic activity of WO3 nanoparticles could be remarkably increased by doping the Zn and Cu impurity. This can be attributed to the fact that the red shift of absorption edge and the trapping effect of the mono and co-doped WO3 nanoparticles. The research result presents a general and effective way to prepare different photocatalysts with enhanced visible and UV light-driven photocatalytic performance. Antibacterial activity of four different WO3 nanoparticles against Escherichia coli bacterium has been assessed by the agar disc method under light irradiation and dark medium. It is concluded from the present findings that WO3 nanoparticles can be used as an efficient antibacterial agent. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Polymorphism and properties of Bi{sub 2}WO{sub 6} doped with pentavalent antimony

    Energy Technology Data Exchange (ETDEWEB)

    Kharitonova, E.P.; Belov, D.A. [M.V. Lomonosov Moscow State University, Leninskie Gory, 119991 Moscow (Russian Federation); Gagor, A.B.; Pietraszko, A.P. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-950 Wrocław (Poland); Alekseeva, O.A. [Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky pr. 59, 119333 Moscow (Russian Federation); Voronkova, V.I., E-mail: voronk@polly.phys.msu.ru [M.V. Lomonosov Moscow State University, Leninskie Gory, 119991 Moscow (Russian Federation)

    2014-04-05

    Highlights: • The limit of Bi{sub 2}W{sub 1−x}Sb{sub x}O{sub 6−y} solid solutions is at x = 0.05. • Bi{sub 2}W{sub 1−x}Sb{sub x}O{sub 6−y} does not fully transform into high-temperature monoclinic phase. • Sb{sup 5+} has a weak effect on the temperatures of the ferroelectric transitions. • γ→γ{sup ‴} transition near 650 °C was observed as strong permittivity peak at 0.01–8 Hz. • The conductivity of Bi{sub 2}W{sub 0.96}Sb{sub 0.04}O{sub 6−y} at 800 °C reaches 0.02 S/cm. -- Abstract: Antimony-containing solid solutions isostructural with bismuth tungstate, Bi{sub 2}WO{sub 6}, have been prepared in air as polycrystalline samples by solid-state reactions and as single crystals by unseeded flux growth. The antimony in the solid solutions is in a pentavalent state and substitutes for tungsten in the structure of Bi{sub 2}WO{sub 6}. The Bi{sub 2}W{sub 1−x}Sb{sub x}O{sub 6−y} solid solutions have been shown to exist in the composition range 0 ⩽ x ⩽ 0.05. We have examined the effect of Sb{sup 5+} doping on the polymorphism and properties of Bi{sub 2}WO{sub 6}. In contrast to undoped Bi{sub 2}WO{sub 6}, antimony-substituted bismuth tungstate does not completely transform into its high-temperature, monoclinic phase at 960 °C and remains two-phase up to temperatures approaching its melting point. Antimony substitution for tungsten has a weak effect on the temperatures of the ferroelectric phase transitions. Heterovalent substitution of Sb{sup 5+} for W{sup 6+} is accompanied by the formation of extra oxygen vacancies and an increase in the electrical conductivity of the solid solutions by one to two orders of magnitude relative to undoped Bi{sub 2}WO{sub 6}.

  3. Advanced nanostructured photocatalysts based on reduced graphene oxide-flower-like Bi{sub 2}WO{sub 6} composites for an augmented simulated solar photoactivity activity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yukun [Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes, Ministry of Education, Hohai University, 1st Xikang Road, Nanjing 210098 (China); Chen, Lin [Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes, Ministry of Education, Hohai University, 1st Xikang Road, Nanjing 210098 (China); College of Environment, Hohai University, 1st Xikang Road, Nanjing 210098 (China); Wang, Yue [Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes, Ministry of Education, Hohai University, 1st Xikang Road, Nanjing 210098 (China); Zhu, Liang, E-mail: liangzhu_hh@163.com [Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes, Ministry of Education, Hohai University, 1st Xikang Road, Nanjing 210098 (China); College of Environment, Hohai University, 1st Xikang Road, Nanjing 210098 (China)

    2016-08-15

    Highlights: • A simple route was proposed to prepare flower-like Bi{sub 2}WO{sub 6} and RGO/Bi{sub 2}WO{sub 6}. • Cipro HCl was degraded firstly by RGO/Bi{sub 2}WO{sub 6} under the visible-light. • 2% RGO/Bi{sub 2}WO{sub 6} exhibited the best removal efficiency. - Abstract: A simple hydrothermal process was proposed to prepare the flower-like Bi{sub 2}WO{sub 6} architectures, and the as-synthesized Bi{sub 2}WO{sub 6} photocatalysts were further processed with the prepared graphene oxide (GO) to form novel reduced graphene oxide (RGO)/Bi{sub 2}WO{sub 6} composites. The nano-materials were characterized with the help of XRD, XPS, SEM, FTIR, UV-DRS, PL techniques to investigate their morphological, physical, optical, and photochemical properties. Photocatalytic performances of the pure flower-like Bi{sub 2}WO{sub 6} architectures and RGO/Bi{sub 2}WO{sub 6} composites were compared and evaluated through the degradation of ciprofloxacin hydrochloride (Cipro HCl) wastewater under the simulated visible light. It was found that the RGO/Bi{sub 2}WO{sub 6} composites displayed enhanced visible light-driven photocatalytic activities. It might be that the RGO loading not only effectively suppressed the electron–hole recombination, but also increased the light absorption ability. The effects of operating condition involved in the photocatalytic process were further examined, and the cycle-stability experiment demonstrated that as-obtained 2% RGO/Bi{sub 2}WO{sub 6} photocatalysts had good photocatalytic repeatability.

  4. Synthesis of Bi2WO6 nanoparticles and its electrochemical properties in different electrolytes for pseudocapacitor electrodes

    International Nuclear Information System (INIS)

    Nithya, V.D.; Kalai Selvan, R.; Kalpana, D.; Vasylechko, Leonid; Sanjeeviraja, C.

    2013-01-01

    Highlights: • A simple, economical and environmentally benign sonochemical technique was utilized for the synthesis of homogeneous Bi 2 WO 6 nanoparticles. • This is the first attempt to employ Bi 2 WO 6 as a supercapacitor electrode material. • Effect of electrolyte on the capacitive behaviour of the material is studied. • Bi 2 WO 6 displays good capacitive behaviour in 1 M KOH compared with 1 M NaOH and 1 M LiOH and possess sufficient capacity retention. • It presented an energy density of 67 Wh/kg in the potential range from −0.9 V to 0.1 V and it would be a promising negative electrode for supercapacitor. -- Abstract: Nanosized Bi 2 WO 6 particles were successfully synthesized by sonochemical method with an objective to develop an inexpensive and eco-friendly electrode material for supercapacitors. The prepared material was subjected to various thermal, structural, morphological, compositional, electrical and electrochemical studies. Bi 2 WO 6 nanoparticle with homogeneous distribution was achieved through sonochemical process. The lattice parameter and atomic positions of Bi 2 WO 6 structure were refined through Reitveld analysis. The electrochemical performance of Bi 2 WO 6 nanoparticles was investigated in various aqueous electrolytes such as 1 M NaOH, 1 M LiOH, 1 M Na 2 SO 4 , 1 M KOH and 6 M KOH solutions. Among these, the material exhibited an enhanced electrochemical performance in KOH electrolyte due to its smaller hydration sphere radius, high ionic mobility and lower equivalent series resistance. The charge–discharge studies rendered a specific capacitance of 608 F/g in 1 M KOH at a current density of 0.5 mA/cm 2 . Bi 2 WO 6 exhibited an excellent coulombic efficiency and specific capacitance of around 304 F/g at 3 mA/cm 2 in the potential range from −0.9 to 0.1 V vs Hg/HgO in 1 M KOH electrolyte. The above results assured that Bi 2 WO 6 could be utilized as suitable negative electrode material for supercapacitor applications and 1 M

  5. WO3 and W Thermal Atomic Layer Etching Using "Conversion-Fluorination" and "Oxidation-Conversion-Fluorination" Mechanisms.

    Science.gov (United States)

    Johnson, Nicholas R; George, Steven M

    2017-10-04

    The thermal atomic layer etching (ALE) of WO 3 and W was demonstrated with new "conversion-fluorination" and "oxidation-conversion-fluorination" etching mechanisms. Both of these mechanisms are based on sequential, self-limiting reactions. WO 3 ALE was achieved by a "conversion-fluorination" mechanism using an AB exposure sequence with boron trichloride (BCl 3 ) and hydrogen fluoride (HF). BCl 3 converts the WO 3 surface to a B 2 O 3 layer while forming volatile WO x Cl y products. Subsequently, HF spontaneously etches the B 2 O 3 layer producing volatile BF 3 and H 2 O products. In situ spectroscopic ellipsometry (SE) studies determined that the BCl 3 and HF reactions were self-limiting versus exposure. The WO 3 ALE etch rates increased with temperature from 0.55 Å/cycle at 128 °C to 4.19 Å/cycle at 207 °C. W served as an etch stop because BCl 3 and HF could not etch the underlying W film. W ALE was performed using a three-step "oxidation-conversion-fluorination" mechanism. In this ABC exposure sequence, the W surface is first oxidized to a WO 3 layer using O 2 /O 3 . Subsequently, the WO 3 layer is etched with BCl 3 and HF. SE could simultaneously monitor the W and WO 3 thicknesses and conversion of W to WO 3 . SE measurements showed that the W film thickness decreased linearly with number of ABC reaction cycles. W ALE was shown to be self-limiting with respect to each reaction in the ABC process. The etch rate for W ALE was ∼2.5 Å/cycle at 207 °C. An oxide thickness of ∼20 Å remained after W ALE, but could be removed by sequential BCl 3 and HF exposures without affecting the W layer. These new etching mechanisms will enable the thermal ALE of a variety of additional metal materials including those that have volatile metal fluorides.

  6. Defect engineering of two-dimensional WO{sub 3} nanosheets for enhanced electrochromism and photoeletrochemical performance

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiaofang; Zheng, Xiaoli; Yan, Bo; Xu, Tao; Xu, Qun, E-mail: qunxu@zzu.edu.cn

    2017-04-01

    Highlights: • We establish a facile strategy by solvothermal reaction and hydrogenation to synthesize 2D WO{sub 3} ultrathin nanosheets with abundant oxygen vacancies. • We find that the hydrogenated WO{sub 3} ultrathin nanosheets exhibit outstanding electrochromism properties. • Moreover, the hydrogenated WO{sub 3} nanosheets also exhibit remarkable photocatalytic performance. • The outstanding electrochromism and photoelectrochemical performances are mainly due to increased oxygen vacancies and narrowed band gap. - Abstract: The capability of introduction of oxygen vacancies in a controlled way has emerged as the heart of modern transition metal oxide semiconductor chemistry. As chemical defects, the oxygen vacancies have been proposed as electron donors, which are prone to increase carrier density and promote charge carrier separation. Herein, we have successfully prepared 2D WO{sub 3} ultrathin nanosheets with abundant surface oxygen vacancies by a combination of facile solvothermal reaction and hydrogenation method. The resultant hydrogenated WO{sub 3} ultrathin nanosheets exhibit remarkable electrochromism and photocatalytic performances compared with the non-hydrogenated samples, mainly due to their increased oxygen vacancies, narrowed band gap coupled with fast charge transfer and enhanced adsorption of visible light.

  7. Performance analysis of CRF-based learning for processing WoT application requests expressed in natural language.

    Science.gov (United States)

    Yoon, Young

    2016-01-01

    In this paper, we investigate the effectiveness of a CRF-based learning method for identifying necessary Web of Things (WoT) application components that would satisfy the users' requests issued in natural language. For instance, a user request such as "archive all sports breaking news" can be satisfied by composing a WoT application that consists of ESPN breaking news service and Dropbox as a storage service. We built an engine that can identify the necessary application components by recognizing a main act (MA) or named entities (NEs) from a given request. We trained this engine with the descriptions of WoT applications (called recipes) that were collected from IFTTT WoT platform. IFTTT hosts over 300 WoT entities that offer thousands of functions referred to as triggers and actions. There are more than 270,000 publicly-available recipes composed with those functions by real users. Therefore, the set of these recipes is well-qualified for the training of our MA and NE recognition engine. We share our unique experience of generating the training and test set from these recipe descriptions and assess the performance of the CRF-based language method. Based on the performance evaluation, we introduce further research directions.

  8. Preparation and optimization of CdWO{sub 4}-polymer nano-composite film as an alpha particle counter

    Energy Technology Data Exchange (ETDEWEB)

    Ziluei, Hossein [Nuclear Science and Technology Research Institute, AEOI, Tehran (Iran, Islamic Republic of); Azimirad, Rouhollah [Malek-Ashtar University of Technology, Tehran (Iran, Islamic Republic of); Mojtahedzadeh Larijani, Majid, E-mail: mmojtahedfr@yahoo.com [Nuclear Science and Technology Research Institute, AEOI, Tehran (Iran, Islamic Republic of); Ziaie, Farhoud [Nuclear Science and Technology Research Institute, AEOI, Tehran (Iran, Islamic Republic of)

    2017-04-21

    In this research work, CdWO{sub 4}/polymer composite films with different thicknesses were prepared using Poly-methyl acrylate polymer and synthesized CdWO{sub 4} powder. The CdWO{sub 4} powder was synthesized by a simple co-precipitation method in the laboratory. X-ray diffraction, photoluminescence, Fourier transformed infrared spectroscopy and energy-dispersive X-ray spectroscopy proved that the CdWO{sub 4} powder was successfully prepared. Moreover, photoluminescence analysis showed that adding polymer does not change the emission peak of CdWO{sub 4}. Also, the responses of all samples were measured using an {sup 241}Am alpha source with 1860 Bq activity. Results showed that the sample having thickness of 177 mg/cm{sup 2} has the best counting efficiency (over 2π geometry) among the others. The efficiency measurement was further evaluated using a {sup 230}Th source whose activity is 190.7 Bq. It revealed that the counting efficiency of this sample for both {sup 241}Am and {sup 230}Th was nearly equal.

  9. Preparation and optimization of CdWO_4-polymer nano-composite film as an alpha particle counter

    International Nuclear Information System (INIS)

    Ziluei, Hossein; Azimirad, Rouhollah; Mojtahedzadeh Larijani, Majid; Ziaie, Farhoud

    2017-01-01

    In this research work, CdWO_4/polymer composite films with different thicknesses were prepared using Poly-methyl acrylate polymer and synthesized CdWO_4 powder. The CdWO_4 powder was synthesized by a simple co-precipitation method in the laboratory. X-ray diffraction, photoluminescence, Fourier transformed infrared spectroscopy and energy-dispersive X-ray spectroscopy proved that the CdWO_4 powder was successfully prepared. Moreover, photoluminescence analysis showed that adding polymer does not change the emission peak of CdWO_4. Also, the responses of all samples were measured using an "2"4"1Am alpha source with 1860 Bq activity. Results showed that the sample having thickness of 177 mg/cm"2 has the best counting efficiency (over 2π geometry) among the others. The efficiency measurement was further evaluated using a "2"3"0Th source whose activity is 190.7 Bq. It revealed that the counting efficiency of this sample for both "2"4"1Am and "2"3"0Th was nearly equal.

  10. Microstructure and thermochromic properties of VO{sub X}-WO{sub X}-VO{sub X} ceramic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Khamseh, S.; Ghahari, M. [Institute for Color Science and Technology, Department of Nanomaterial and Nanocoatings, Tehran (Iran, Islamic Republic of); Araghi, H. [Islamic Azad University, Department of Materials Engineering, Science and Research Branch, Tehran (Iran, Islamic Republic of); Faghihi Sani, M.A. [Sharif University of Technology, Department of Materials Science and Engineering, Tehran (Iran, Islamic Republic of)

    2016-03-15

    W-doped VO{sub 2} films have been synthesized via oxygen annealing of V-W-V (vanadium-tungsten-vanadium) multilayered films. The effects of middle layer's thickness of V-W-V multilayered film on structure and properties of VO{sub X}-WO{sub X}-VO{sub X} ceramic thin films were investigated. The as-deposited V-W-V multilayered film showed amorphous-like structure when mixed structure of VO{sub 2} (M) and VO{sub 2} (B) was formed in VO{sub X}-WO{sub X}-VO{sub X} ceramic thin films. Tungsten content of VO{sub X}-WO{sub X}-VO{sub X} ceramic thin films increased with increasing middle layer's thickness. With increasing middle layer's thickness, room temperature square resistance (R{sub sq}) of VO{sub X}-WO{sub X}-VO{sub X} ceramic thin films increased from 65 to 86 kΩ/sq. The VO{sub X}-WO{sub X}-VO{sub X} ceramic thin film with the thinnest middle layer showed significant SMT (semiconductor-metal transition) when SMT became negligible on increasing middle layer's thickness. (orig.)

  11. Synthesis and characterizations of isolated WO{sub 4} anchored on mesoporous TiTUD-1 support

    Energy Technology Data Exchange (ETDEWEB)

    Pachamuthu, Muthusamy P. [Department of Chemistry, Bannari Amman Institute of Technology, Sathyamangalam, Erode, 638401 (India); Maheswari, Rajamanickam [Center for Environmentally Beneficial Catalysis (CEBC), The University of Kansas, Lawrence, KS, 66047 (United States); Ramanathan, Anand, E-mail: anand@ku.edu [Center for Environmentally Beneficial Catalysis (CEBC), The University of Kansas, Lawrence, KS, 66047 (United States)

    2017-04-30

    Highlights: • Incorporation of (WO{sub 4}{sup 2−}) species into amorphous mesoporous silicate TiTUD-1. • Typical TUD-1 structure with dispersed Ti{sup 4+} and WO{sub 4}{sup 2−} species. • FT Raman and XPS results evidenced the WO{sub 4}{sup 2−} species dispersion. • Catalyst with 20% W loading yields higher conversion in esterification reaction. - Abstract: The titanium incorporated mesoporous silicate TUD-1 (Si/Ti ratio 40) was synthesized by non-surfactant route, and utilized as a support for tungstate (WO{sub 4}{sup 2−}) species with variable loading (5–30 wt%). The structural and textural properties of these samples were evaluated from X-ray diffraction (XRD) and N{sub 2} physisorption studies. Diffuse reflectance UV–vis (DR UV–vis), Fourier transform infrared (FTIR), Fourier transform Raman (FT Raman) spectra evidenced the Ti{sup 4+} coordination and the formation of WO{sub 4}{sup 2−} species, further supported by X-ray photoelectron spectroscopy (XPS) studies. Scanning electron microscope–energy dispersive X-ray analysis (SEM-EDAX), High resolution transmission electron microscope (HRTEM) further support the materials morphology corroborating other characterizations. The catalytic activities of these materials were tested in the liquid phase, solvent free esterification of acetic acid with n-butanol. About 95% of acetic acid conversion resulted by these catalysts with 8 h of reaction time.

  12. Per-service supervised learning for identifying desired WoT apps from user requests in natural language.

    Directory of Open Access Journals (Sweden)

    Young Yoon

    Full Text Available Web of Things (WoT platforms are growing fast so as the needs for composing WoT apps more easily and efficiently. We have recently commenced the campaign to develop an interface where users can issue requests for WoT apps entirely in natural language. This requires an effort to build a system that can learn to identify relevant WoT functions that fulfill user's requests. In our preceding work, we trained a supervised learning system with thousands of publicly-available IFTTT app recipes based on conditional random fields (CRF. However, the sub-par accuracy and excessive training time motivated us to devise a better approach. In this paper, we present a novel solution that creates a separate learning engine for each trigger service. With this approach, parallel and incremental learning becomes possible. For inference, our system first identifies the most relevant trigger service for a given user request by using an information retrieval technique. Then, the learning engine associated with the trigger service predicts the most likely pair of trigger and action functions. We expect that such two-phase inference method given parallel learning engines would improve the accuracy of identifying related WoT functions. We verify our new solution through the empirical evaluation with training and test sets sampled from a pool of refined IFTTT app recipes. We also meticulously analyze the characteristics of the recipes to find future research directions.

  13. Crystal structure and phase transition in (NH4)3WO2F5: from dynamic to static orientational disorder.

    Science.gov (United States)

    Udovenko, Anatoly; Laptash, Natalia

    2015-08-01

    Single crystals of tungsten double salt (NH4)3WO2F5 = (NH4)3[WO2F4]F have been synthesized by solid-state reaction or from fluoride solution and its crystal structures at 296 and 193 K were determined by X-ray diffraction. At room temperature, the crystal structure of the compound is dynamically disordered with the ligand atoms statistically distributed on two positions (6e and 24m) of the Pm3m unit cell [a = 6.0298 (1) Å], and the tungsten atom dynamically disordered on 12 orientations forming a spatial cuboctahedron [W12] that enables the real geometry of cis-WO2F4 octahedron to be determined with two short W-O distances. On cooling, the compound undergoes a first-order phase transition with the symmetry change Pm3m → Pa3 and a doubling of the unit-cell parameter [a = 11.9635 (7) Å]. The ligand F(O) atoms statistically occupy two general 24d sites and form W1X6 and W2X6 octahedra, in which the O and F atoms are not crystallographically different that means a static orientational disorder of (NH4)3WO2F5.

  14. Synthesis and Visible-Light Photocatalytic Property of Bi2WO6Hierarchical Octahedron-Like Structures

    Directory of Open Access Journals (Sweden)

    Li Yuanyuan

    2008-01-01

    Full Text Available Abstract A novel octahedron-like hierarchical structure of Bi2WO6has been fabricated by a facile hydrothermal method in high quantity. XRD, SEM, TEM, and HRTEM were used to characterize the product. The results indicated that this kind of Bi2WO6crystals had an average size of ~4 μm, constructed by quasi-square single-crystal nanosheets assembled in a special fashion. The formation of octahedron-like hierarchical structure of Bi2WO6depended crucially on the pH value of the precursor suspensions. The photocatalytic activity of the hierarchical Bi2WO6structures toward RhB degradation under visible light was investigated, and it was found to be significantly better than that of the sample fabricated by SSR. The better photocatalytic property should be strongly associated with the high specific surface area and the abundant pore structure of the hierarchical octahedron-like Bi2WO6.

  15. Efficient visible-light photocatalytic and enhanced photocorrosion inhibition of Ag2WO4 decorated MoS2 nanosheets

    Science.gov (United States)

    Thangavel, Sakthivel; Thangavel, Srinivas; Raghavan, Nivea; Alagu, Raja; Venugopal, Gunasekaran

    2017-11-01

    The use of two-dimensional nanomaterials as co-catalysts in the photodegradation of toxic compounds using light irradiation is an attractive ecofriendly process. In this study, we prepared a novel MoS2/Ag2WO4 nanohybrid via a one-step hydrothermal approach and the photocatalytic properties were investigated by the degradation of methyl-orange under stimulated irradiation. The nanohybrid exhibits enhanced efficiency in dye degradation compared to the bare Ag2WO4 nanorods; the same has been evidently confirmed with UV-visible spectra and total organic carbon removal analysis. The pseudo-first order rate constant of the nanohybrid is nearly 1.8 fold higher than that of the bare Ag2WO4 nanorods. With the aid of classical radical quenching and photoluminescence spectral analysis, a reasonable mechanism has been derived for the addition of MoS2 to nanohybrids to enhance the photocatalytic efficiency. MoS2 prevents photocorrosion of Ag2WO4 and also diminishes the number of photogenerated electron-hole recombination. Our findings could provide new insights in understanding the mechanism of the MoS2/Ag2WO4 nanohybrid as an efficient photocatalyst suitable for waste-water treatment and remedial applications.

  16. Immobilized WO3 nanoparticles on graphene oxide as a photo-induced antibacterial agent against UV-resistant Bacillus pumilus

    Science.gov (United States)

    Hosseini, Farshad; Rasuli, Reza; Jafarian, Vahab

    2018-04-01

    We present the antibacterial and photo-catalytic activity of immobilized WO3 nanoparticles on graphene oxide sheets. WO3 nanoparticles were immobilized on graphene oxide using the arc discharge method in arc currents of 5, 20, 40 and 60 A. Tauc plots of the UV-visible spectra show that the band gap of the prepared samples decreases (to ~2.7 eV) with respect to the WO3 nanoparticles. Photo-catalytic activity was examined by the degradation of rhodamine B under ultra-violet irradiation and the results show that the photo-catalytic activity of WO3 nanoparticles is increased by immobilizing them on graphene oxide sheets. In addition, the photo-degradation yield of the samples prepared by the 5 A arc current is 84% in 120 min, which is more than that of the other samples. The antibacterial activity of the prepared samples was studied against Bacillus pumilus (B. pumilus) bacteria, showing high resistance to ultra-violet exposure. Our results show that the bare and immobilized WO3 nanoparticles become more active under UV irradiation and their antibacterial properties are comparable with Ag nanoparticles. Besides this, the results show that although the photo-catalytic activity of the post-annealed samples at 500 °C is less than the as-prepared samples, it is, however, more active against B. pumilus bacteria under UV irradiation.

  17. Gas Sensing Properties of Metal Doped WO3 Thin Film Sensors Prepared by Pulsed Laser Deposition and DC Sputtering Process

    Science.gov (United States)

    Bhuiyan, Md. Mosharraf Hossain; Ueda, Tsuyoshi; Ikegami, Tomoaki; Ebihara, Kenji

    2006-10-01

    Tungsten trioxide (WO3) thin films gas sensors were prepared by the KrF excimer pulsed laser deposition (PLD) method. The films were prepared on the quartz glass, silicon and also on the Al2O3 sensor substrates with platinum interdigitated electrodes. The effect of doping of the platinum (Pt), palladium (Pd) or gold (Au) on the WO3 thin film was also investigated. These metals were doped to the WO3 thin film by the DC sputtering process during the PLD. The substrate temperature and the oxygen pressure were 400 °C and 100 mTorr, respectively, during the deposition. The films were characterized by atomic force microscopy (AFM) and X-ray diffraction (XRD). The sensitivity of the prepared sensors to 60 ppm NO gas was examined using the two terminal resistance method in a chamber at atmospheric pressure and operating temperatures of 25-350 °C. The sensitivity of the WO3 thin films doped with Pt, Pd, or Au was found to be higher than that of the undoped WO3 thin film.

  18. Facile synthesis of NiWO4/reduced graphene oxide nanocomposite with excellent capacitive performance for supercapacitors

    International Nuclear Information System (INIS)

    Xu, Xiaowei; Pei, Liyuan; Yang, Yang; Shen, Jianfeng; Ye, Mingxin

    2016-01-01

    NiWO 4 /reduced graphene oxide (NWG) nanocomposite was successfully synthesized through a facile one-pot solvothermal method for the first time. The resulting nanocomposite is composed of NiWO 4 nanoparticles that are uniformly attached on graphene sheets by in situ reducing. The as-prepared NWG composite has been systematically characterized by Powder X-ray diffraction, Fourier transform infrared spectra, Raman spectroscopy, Thermogravimetric analysis, Scanning electron microscopy, Transmission electron microscopy, X-ray photoelectron spectra, and Brunauer–Emmett–Teller analysis. The capacitive performances of the as-prepared NWG composite as electrode material are investigated. It is found that the NWG composite exhibits a high specific capacitance up to 1031.3 F g −1 at a current density of 0.5 A g −1 . The greatly enhanced capacitive performance of the NWG electrode can be attributed to the synergetic effect of NiWO 4 nanoparticles and RGO, which provides conducting channels and active sites. The cyclic stability tests demonstrated no decreases of its initial values after 5000 cycles, suggesting that such hybrid electrode possesses a great potential application in energy-storage devices. - Highlights: • NiWO 4 /RGO composite was successfully prepared through a facile solvothermal method. • The NiWO 4 /RGO composite shows a high specific capacitance of 1031.3 F g −1 . • Enhanced electrical conductivity leads to superior electrochemical performance.

  19. Per-service supervised learning for identifying desired WoT apps from user requests in natural language.

    Science.gov (United States)

    Yoon, Young

    2017-01-01

    Web of Things (WoT) platforms are growing fast so as the needs for composing WoT apps more easily and efficiently. We have recently commenced the campaign to develop an interface where users can issue requests for WoT apps entirely in natural language. This requires an effort to build a system that can learn to identify relevant WoT functions that fulfill user's requests. In our preceding work, we trained a supervised learning system with thousands of publicly-available IFTTT app recipes based on conditional random fields (CRF). However, the sub-par accuracy and excessive training time motivated us to devise a better approach. In this paper, we present a novel solution that creates a separate learning engine for each trigger service. With this approach, parallel and incremental learning becomes possible. For inference, our system first identifies the most relevant trigger service for a given user request by using an information retrieval technique. Then, the learning engine associated with the trigger service predicts the most likely pair of trigger and action functions. We expect that such two-phase inference method given parallel learning engines would improve the accuracy of identifying related WoT functions. We verify our new solution through the empirical evaluation with training and test sets sampled from a pool of refined IFTTT app recipes. We also meticulously analyze the characteristics of the recipes to find future research directions.

  20. Role of indium tin oxide electrode on the microstructure of self-assembled WO3-BiVO4 hetero nanostructures

    Science.gov (United States)

    Song, Haili; Li, Chao; Van, Chien Nguyen; Dong, Wenxia; Qi, Ruijuan; Zhang, Yuanyuan; Huang, Rong; Chu, Ying-Hao; Duan, Chun-Gang

    2017-11-01

    Self-assembled WO3-BiVO4 nanostructured thin films were grown on a (001) yttrium stabilized zirconia (YSZ) substrate by the pulsed laser deposition method with and without the indium tin oxide (ITO) bottom electrode. Their microstructures including surface morphologies, crystalline phases, epitaxial relationships, interface structures, and composition distributions were investigated by scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray energy dispersive spectroscopy. In both samples, WO3 formed nanopillars embedded into the monoclinic BiVO4 matrix with specific orientation relationships. In the sample with the ITO bottom electrode, an atomically sharp BiVO4/ITO interface was formed and the orthorhombic WO3 nanopillars were grown on a relaxed BiVO4 buffer layer with a mixed orthorhombic and hexagonal WO3 transition layer. In contrast, a thin amorphous layer appears at the interfaces between the thin film and the YSZ substrate in the sample without the ITO electrode. In addition, orthorhombic Bi2WO6 lamellar nanopillars were formed between WO3 and BiVO4 due to interdiffusion. Such a WO3-Bi2WO6-BiVO4 double heterojunction photoanode may promote the photo-generated charge separation and further improve the photoelectrochemical water splitting properties.

  1. A comparative study of humidity sensing and photocatalytic applications of pure and nickel (Ni)-doped WO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ramkumar, S. [Bannari Amman Institute of Technology, Department of Physics, Erode, Tamilnadu (India); Rajarajan, G. [Vidhya Mandhir Institute of Technology, Department of Physics, Erode, Tamilnadu (India)

    2017-06-15

    Nanocrystalline of pristine and nickel (Ni)-doped tungsten trioxide (WO{sub 3}) thin films was deposited by chemical bath deposition method. The concentrations of Ni ions were varied from 0 to 10 wt%. In order to improve the crystallinity of the films were annealed at 600 C for 2 h in the ambient atmosphere. X-ray diffraction results reveal that the WO{sub 3} doped with nickel crystallizes in monoclinic structure and the results are in good agreement with the standard JCPDS data (card no: 83-0951). AFM micrographs reveal that average grain size of about 27-39 nm for pure and Ni-doped WO{sub 3} thin films. In addition, the band gap of the Ni-doped WO{sub 3} nanostructures is facilely tunable by controlling the Ni contents. The humidity sensor setup was fabricated and measured for pure and Ni-doped WO{sub 3} thin film sensor with various level of RH (10-90%). The Ni-doped WO{sub 3} sensor showed fast response and high sensitivity than pure WO{sub 3}. The photocatalytic activities of the films were evaluated by degradation of methyl orange, methylene blue and phenol in an aqueous solution under visible light irradiation. The photocatalytic activity of WO{sub 3} nanostructures could be remarkably enhanced by doping the Ni impurity. (orig.)

  2. A novel nitrite biosensor based on the direct electron transfer hemoglobin immobilized in the WO3 nanowires with high length–diameter ratio

    International Nuclear Information System (INIS)

    Liu, Hui; Duan, Congyue; Yang, Chenhui; Chen, Xianjin; Shen, Wanqiu; Zhu, Zhenfeng

    2015-01-01

    WO 3 nanowires (WO 3 NWs) with high length–diameter ratio have been synthesized through a simple synthetic route without any additive and then used to immobilize hemoglobin (Hb) to fabricate a mediator-free biosensor. The morphology and structure of WO 3 NWs were characterized by scanning electron microscopy, transmission electronic microscopy and X-ray diffraction. Spectroscopic and electrochemical results revealed that WO 3 NWs are an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. Meanwhile, due to unique morphology and property of the WO 3 nanowires, the direct electron transfer of Hb is facilitated and the prepared biosensors displayed good performance for the detection of nitrite with a wide linear range of 1 to 4200 μM, as well as an extremely low detection limit of 0.28 μM. The WO 3 nanowires with high length–diameter ratio could be a promising matrix for the fabrication of mediator-free biosensors, and may find wide potential applications in environmental analysis and biomedical detection. - Highlights: • The WO 3 NWs with high length–diameter ratio have been synthesized. • The WO 3 NWs were used to immobilize Hb to fabricate a mediator-free biosensor. • The biosensor displays a wide linear range of 1–4200 μM for nitrite. • The biosensor exhibits an extremely low detection limit of 0.28 μM for nitrite

  3. In situ synthesis of Bi2S3 sensitized WO3 nanoplate arrays with less interfacial defects and enhanced photoelectrochemical performance

    Science.gov (United States)

    Liu, Canjun; Yang, Yahui; Li, Wenzhang; Li, Jie; Li, Yaomin; Chen, Qiyuan

    2016-03-01

    In this study, Bi2S3 sensitive layer has been grown on the surface of WO3 nanoplate arrays via an in situ approach. The characterization of samples were carried out using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and ultraviolet-visible absorption spectroscopy (UV-vis). The results show that the Bi2S3 layer is uniformly formed on the surface of WO3 nanoplates and less interfacial defects were observed in the interface between the Bi2S3 and WO3. More importantly, the Bi2S3/WO3 films as photoanodes for photoelectrochemical (PEC) cells display the enhanced PEC performance compared with the Bi2S3/WO3 films prepared by a sequential ionic layer adsorption reaction (SILAR) method. In order to understand the reason for the enhanced PEC properties, the electron transport properties of the photoelectrodes were studied by using the transient photocurrent spectroscopy and intensity modulated photocurrent spectroscopy (IMPS). The Bi2S3/WO3 films prepared via an in situ approach have a greater transient time constant and higher electron transit rate. This is most likely due to less interfacial defects for the Bi2S3/WO3 films prepared via an in situ approach, resulting in a lower resistance and faster carrier transport in the interface between WO3 and Bi2S3.

  4. Subsolidus phase relations of the SrO–WO3–CuO system at 800 °C in air

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Norby, Poul

    2012-01-01

    The subsolidus phase relations of the SrO–WO3–CuO system were investigated in air. The samples were equilibrated at 800 °C. Under these conditions, eight binary oxides are stable. The pseudo-ternary section contains two ternary oxide phases: the previously described Sr2CuWO6 phase as well as a new...

  5. Phase relations and crystal structures in the systems (Bi,Ln)2WO6 and (Bi,Ln)2MoO6 (Ln=lanthanide)

    International Nuclear Information System (INIS)

    Berdonosov, Peter S.; Charkin, Dmitri O.; Knight, Kevin S.; Johnston, Karen E.; Goff, Richard J.; Dolgikh, Valeriy A.; Lightfoot, Philip

    2006-01-01

    Several outstanding aspects of phase behaviour in the systems (Bi,Ln) 2 WO 6 and (Bi,Ln) 2 MoO 6 (Ln=lanthanide) have been clarified. Detailed crystal structures, from Rietveld refinement of powder neutron diffraction data, are provided for Bi 1.8 La 0.2 WO 6 (L-Bi 2 WO 6 type) and BiLaWO 6 , BiNdWO 6 , Bi 0.7 Yb 1.3 WO 6 and Bi 0.7 Yb 1.3 WO 6 (all H-Bi 2 WO 6 type). Phase evolution within the solid solution Bi 2- x La x MoO 6 has been re-examined, and a crossover from γ(H)-Bi 2 MoO 6 type to γ-R 2 MoO 6 type is observed at x∼1.2. A preliminary X-ray Rietveld refinement of the line phase BiNdMoO 6 has confirmed the α-R 2 MoO 6 type structure, with a possible partial ordering of Bi/Nd over the three crystallographically distinct R sites. - Graphical abstract: A summary of phase relations in the lanthanide-doped bismuth tungstate and bismuth molybdate systems is presented, together with some additional structural data on several of these phases

  6. Plasmodium falciparum parasites expressing pregnancy-specific variant surface antigens adhere strongly to the choriocarcinoma cell line BeWo

    DEFF Research Database (Denmark)

    Haase, Rikke N; Megnekou, Rosette; Lundquist, Maja

    2006-01-01

    Placenta-sequestering Plasmodium falciparum parasites causing pregnancy-associated malaria express pregnancy-specific variant surface antigens (VSA(PAM)). We report here that VSA(PAM)-expressing patient isolates adhere strongly to the choriocarcinoma cell line BeWo and that the BeWo line can...... be used to efficiently select for VSA(PAM) expression in vitro....

  7. Effects of micro-sized and nano-sized WO_3 on mass attenauation coefficients of concrete by using MCNPX code

    International Nuclear Information System (INIS)

    Tekin, H.O.; Singh, V.P.; Manici, T.

    2017-01-01

    In the present work the effect of tungsten oxide (WO_3) nanoparticles on mass attenauation coefficients of concrete has been investigated by using MCNPX (version 2.4.0). The validation of generated MCNPX simulation geometry has been provided by comparing the results with standard XCOM data for mass attenuation coefficients of concrete. A very good agreement between XCOM and MCNPX have been obtained. The validated geometry has been used for definition of nano-WO_3 and micro-WO_3 into concrete sample. The mass attenuation coefficients of pure concrete and WO_3 added concrete with micro-sized and nano-sized have been compared. It was observed that shielding properties of concrete doped with WO_3 increased. The results of mass attenauation coefficients also showed that the concrete doped with nano-WO_3 significanlty improve shielding properties than micro-WO_3. It can be concluded that addition of nano-sized particles can be considered as another mechanism to reduce radiation dose. - Highlights: • It was found that size of the WO_3 affected the mass attenuation coefficients of concrete in all photon energies.

  8. Nano Ag@AgBr surface-sensitized Bi{sub 2}WO{sub 6} photocatalyst: oil-in-water synthesis and enhanced photocatalytic degradation

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shuanglong; Liu, Li; Hu, Jinshan; Liang, Yinghua, E-mail: liangyh@heuu.edu.cn; Cui, Wenquan, E-mail: wkcui@163.com

    2015-01-01

    Graphical abstract: - Highlights: • The plasmatic Ag@AgBr surface-sensitized Bi{sub 2}WO{sub 6} composite photocatalysts. • Ag@AgBr greatly increased visible-light absorption for Bi{sub 2}WO{sub 6}. • The plasmonic photocatalysts exhibited enhanced activity for the degradation of MB, phenol and salicylic acid. - Abstract: Nano Ag@AgBr decorated on the surface of flower-like Bi{sub 2}WO{sub 6} (hereafter designated Ag@AgBr/Bi{sub 2}WO{sub 6}) were prepared via a facile oil-in-water self-assembly method. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy (DRS), etc. The characterization results indicated that nano Ag@AgBr was observed to be evenly dispersed on the surface of Bi{sub 2}WO{sub 6}, and was approximately 20 nm in size. Ag@AgBr/Bi{sub 2}WO{sub 6} composites exhibited excellent UV–vis absorption, due to quantum dimension effect of Ag@AgBr, the surface plasmonic resonance (SPR) of Ag nanoparticles and the special flower-like structure of Bi{sub 2}WO{sub 6}. The photoelectrochemical measurement verified that the suitable band potential of Ag@AgBr and Bi{sub 2}WO{sub 6} and the existence of metal Ag resulted in the high efficiency in charge separation of the composite. The photocatalytic activities of the Ag@AgBr/Bi{sub 2}WO{sub 6} samples were examined under visible-light irradiation for the degradation of methylene blue (MB). The composite presented excellent photocatalytic activity due to the synergetic effect of Bi{sub 2}WO{sub 6}, AgBr, and Ag nanoparticles. The Ag@AgBr(20 wt.%)/Bi{sub 2}WO{sub 6} sample exhibited the best photocatalytic activity, degrading 95.03% MB after irradiation for 2 h, which was respectively 1.29 times and 1.28 times higher than that of Ag@AgBr and Bi{sub 2}WO{sub 6} photocatalyst. Meanwhile, phenol and salicylic acid were degraded to further prove the degradation ability of Ag@AgBr/Bi{sub 2

  9. Enhanced electrochromic and energy storage performance in mesoporous WO3 film and its application in a bi-functional smart window.

    Science.gov (United States)

    Wang, Wei-Qi; Wang, Xiu-Li; Xia, Xin-Hui; Yao, Zhu-Jun; Zhong, Yu; Tu, Jiang-Ping

    2018-05-03

    Construction of multifunctional photoelectrochemical energy devices is of great importance to energy saving. In this study, we have successfully prepared a mesoporous WO3 film on FTO glass via a facile dip-coating sol-gel method; the designed mesoporous WO3 film exhibited advantages including high transparency, good adhesion and high porosity. Also, multifunctional integrated energy storage and optical modulation ability are simultaneously achieved by the mesoporous WO3 film. Impressively, the mesoporous WO3 film exhibits a noticeable electrochromic energy storage performance with a large optical modulation up to 75.6% at 633 nm, accompanied by energy storage with a specific capacity of 75.3 mA h g-1. Furthermore, a full electrochromic energy storage window assembled with the mesoporous WO3 anode and PANI nanoparticle cathode is demonstrated with large optical modulation and good long-term stability. Our research provides a new route to realize the coincident utilization of optical-electrochemical energy.

  10. Ln{sup 3+}:KLu(WO{sub 4}){sub 2}/KLu(WO{sub 4}){sub 2} epitaxial layers: Crystal growth and physical characterisation

    Energy Technology Data Exchange (ETDEWEB)

    Silvestre, O.; Pujol, M.C.; Sole, R.; Bolanos, W.; Carvajal, J.J.; Massons, J.; Aguilo, M. [Fisica i Cristal.lografia de Materials (FiCMA), Universitat Rovira i Virgili, Campus Sescelades c/Marcel.li Domingo, s/n E-43007 Tarragona (Spain); Diaz, F. [Fisica i Cristal.lografia de Materials (FiCMA), Universitat Rovira i Virgili, Campus Sescelades c/Marcel.li Domingo, s/n E-43007 Tarragona (Spain)], E-mail: f.diaz@urv.cat

    2008-01-15

    Monoclinic epitaxial layers of single doped KLu{sub 1-x}Ln{sub x}(WO{sub 4}){sub 2} (Ln{sup 3+} = Yb{sup 3+} and Tm{sup 3+}) have been grown on optically passive KLuW substrates by liquid phase epitaxy (LPE) technique using K{sub 2}W{sub 2}O{sub 7} as solvent. The ytterbium content in the layer is in the range of 0.05 < x < 0.75 atomic substitution and the studied thulium concentrations are 0.05 < x < 0.10. The grown epitaxies are free of macroscopic defects and only in highly ytterbium-doped epilayers do some cracks or inclusions appear. The refractive indices of the epilayers were determined. The absorption and emission cross sections of ytterbium and thulium in KLuW are characterised and laser generation results are presented and discussed.

  11. IR spectra and structure of glasses in the BaO-WO3-P2O5 system

    International Nuclear Information System (INIS)

    Miroshnichenko, O.Ya.; Mombelli, V.V.

    1979-01-01

    Studied are IR absorption spectra and determined are the main structural characteristics of tungstophosphate glasses of the BaO-WO 3 -P 2 O 5 system in all the area of glass formation. It is shown that the main structural components of their anion network are phosphate chains consisting of PO 4 tetrahedrons and tungstate chains consisting of WO 4 tetrahedrons and of WO 6 octahedrons. These chains are connected by P-O-W bridges into three-dimentional tungstophosphate network, where the ratio of phosphate and tungstate structural units and their polymerization degree change without limits depending on the glass composition. Analysis of concentration frequency dependence and spectral band intensity permit to clarify the effect of each component on the glass structure in all the area of glass formation of the triple system

  12. WO3/Pt nanoparticles are NADPH oxidase biomimetics that mimic effector cells in vitro and in vivo

    International Nuclear Information System (INIS)

    Clark, Andrea J; Coury, Emma L; Meilhac, Alexandra M; Petty, Howard R

    2016-01-01

    To provide a means of delivering an artificial immune effector cell-like attack on tumor cells, we report the tumoricidal ability of inorganic WO 3 /Pt nanoparticles that mimic a leukocyte’s functional abilities. These nanoparticles route electrons from organic structures and electron carriers to form hydroxyl radicals within tumor cells. During visible light exposure, WO 3 /Pt nanoparticles manufacture hydroxyl radicals, degrade organic compounds, use NADPH, trigger lipid peroxidation, promote lysosomal membrane disruption, promote the loss of reduced glutathione, and activate apoptosis. In a model of advanced breast cancer metastasis to the eye’s anterior chamber, we show that WO 3 /Pt nanoparticles prolong the survival of 4T1 tumor-bearing Balb/c mice. This new generation of inorganic photosensitizers do not photobleach, and therefore should provide an important therapeutic advance in photodynamic therapy. As biomimetic nanoparticles destroy targeted cells, they may be useful in treating ocular and other forms of cancer. (paper)

  13. Synthesis and Characterization of Graphene Oxide-Modified Bi2WO6 and Its Use as Photocatalyst

    Directory of Open Access Journals (Sweden)

    Xiaoyue Hu

    2016-01-01

    Full Text Available A Bi2WO6 photocatalyst modified with graphene was synthesized in a two-step template-free hydrothermal process. The prepared samples were characterized to explore their properties. The photocatalytic activities of the prepared samples were investigated by degrading dye model, Rhodamine B (RhB, under visible light irradiation. This showed that the modified Bi2WO6 photocatalyst with 1.2 wt% of graphene greatly improved photocatalytic activity during the degradation of dye pollutants, compared to pure Bi2WO6. The enhancement can be interpreted as the integrated effects of ultrahigh charge carriers’ mobility and high adsorption of RhB on graphene. Additionally, effects including catalysts dosage amount, pH of RhB solution, and temperature of reactor on the photocatalytically degrading RhB were also studied and discussed.

  14. Characterization of scintillating CaWO{sub 4} crystals for the CRESST experiment using two-photon excitation

    Energy Technology Data Exchange (ETDEWEB)

    Hampf, Raphael; Dandl, Thomas; Muenster, Andrea; Oberauer, Lothar; Roth, Sabine; Schoenert, Stefan; Ulrich, Andreas [Physik-Department and Excellence Cluster Universe, Technische Universitaet Muenchen, D-85747 Garching (Germany)

    2016-07-01

    In the CRESST experiment for direct dark matter search, phonon and photon signals from cryogenic CaWO{sub 4} crystals are used to search for WIMP-induced nuclear recoil events. We present a novel table-top setup in which the scintillation of CaWO{sub 4} is induced by 0.7 ns laser pulses of 355 nm wavelength. The excitation occurs via two-photon absorption in the bulk material. The scintillation light is observed by time resolved optical spectroscopy. By varying the focusing of the laser-beam the excitation density can be made high enough to study quenching effects due to exciton-exciton annihilation. This allows to perform experiments to test models for the quenching factors of different ionizing projectiles in CaWO{sub 4} which are used to identify these projectiles on an event by event basis.

  15. Morphology and structural studies of WO_3 films deposited on SrTiO_3 by pulsed laser deposition

    International Nuclear Information System (INIS)

    Kalhori, Hossein; Porter, Stephen B.; Esmaeily, Amir Sajjad; Coey, Michael; Ranjbar, Mehdi; Salamati, Hadi

    2016-01-01

    Highlights: • Highly oriented WO_3 stoichiometric films were determined using pulsed laser deposition method. • Effective parameters on thin films including temperature, oxygen partial pressure and laser energy fluency was studied. • A phase transition was observed in WO_3 films at 700 °C from monoclinic to tetragonal. - Abstract: WO_3 films have been grown by pulsed laser deposition on SrTiO_3 (001) substrates. The effects of substrate temperature, oxygen partial pressure and energy fluence of the laser beam on the physical properties of the films were studied. Reflection high-energy electron diffraction (RHEED) patterns during and after growth were used to determine the surface structure and morphology. The chemical composition and crystalline phases were obtained by XPS and XRD respectively. AFM results showed that the roughness and skewness of the films depend on the substrate temperature during deposition. Optimal conditions were determined for the growth of the highly oriented films.

  16. WO3/Pt nanoparticles are NADPH oxidase biomimetics that mimic effector cells in vitro and in vivo

    Science.gov (United States)

    Clark, Andrea J.; Coury, Emma L.; Meilhac, Alexandra M.; Petty, Howard R.

    2016-02-01

    To provide a means of delivering an artificial immune effector cell-like attack on tumor cells, we report the tumoricidal ability of inorganic WO3/Pt nanoparticles that mimic a leukocyte’s functional abilities. These nanoparticles route electrons from organic structures and electron carriers to form hydroxyl radicals within tumor cells. During visible light exposure, WO3/Pt nanoparticles manufacture hydroxyl radicals, degrade organic compounds, use NADPH, trigger lipid peroxidation, promote lysosomal membrane disruption, promote the loss of reduced glutathione, and activate apoptosis. In a model of advanced breast cancer metastasis to the eye’s anterior chamber, we show that WO3/Pt nanoparticles prolong the survival of 4T1 tumor-bearing Balb/c mice. This new generation of inorganic photosensitizers do not photobleach, and therefore should provide an important therapeutic advance in photodynamic therapy. As biomimetic nanoparticles destroy targeted cells, they may be useful in treating ocular and other forms of cancer.

  17. Enhanced performance of direct Z-scheme CuS-WO 3 system towards photocatalytic decomposition of organic pollutants under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Song, Chundong; Wang, Xiang; Zhang, Jing; Chen, Xuebing; Li, Can

    2017-12-01

    CuS-WO3 composites were synthesized by an in situ solution method at low temperature. The crystalline phase, morphology, particle size, and the optical properties of CuS-WO3 samples were characterized by XRD, SEM, XPS, and UV–vis diffuse reflectance spectra. CuS-WO3 composites showed much higher activity for photocatalytic degradation of RhB as compared with WO3 and CuS. The degradation rate constant over 1 wt% CuS-WO3 catalyst was 4.4 times and 9.2 times higher than that of WO3 and CuS, respectively. It is found that holes (h+) and superoxide radical anions (O2-) are the dominant reactive species by using methanol, disodium ethylenediaminetetraacetate (EDTA) and ascorbic acid as scavengers. Band structure analysis shows that bottom of CB of WO3 is very similar with and higher (ca. 0.01 eV) than the top of VB of CuS. The results of PL showed that the similarity renders the recombination between photogenerated holes on the VB of CuS and photogenerated electrons on the CB of WO3 possible and easy, forming a direct Z-scheme in CuS-WO3. This result in that more electrons in the CB of CuS and holes in the VB of WO3 survived, and then participated in the photocatalytic degradation of RhB, showing an increased activity.

  18. Exfoliated thin Bi{sub 2}MoO{sub 6} nanosheets supported on WO{sub 3} electrode for enhanced photoelectrochemical water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Ying; Jia, Yulong; Wang, Lina [State Key Laboratory for Oxo Synthesis & Selective Oxidation, and National Engineering Research Center for Fine Petrochemical Intermediates, Lanzhou Institute of Chemical Physics, CAS, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Yang, Min [State Key Laboratory for Oxo Synthesis & Selective Oxidation, and National Engineering Research Center for Fine Petrochemical Intermediates, Lanzhou Institute of Chemical Physics, CAS, Lanzhou 730000 (China); Bi, Yingpu, E-mail: yingpubi@licp.cas.cn [State Key Laboratory for Oxo Synthesis & Selective Oxidation, and National Engineering Research Center for Fine Petrochemical Intermediates, Lanzhou Institute of Chemical Physics, CAS, Lanzhou 730000 (China); Qi, Yanxing, E-mail: qiyx@licp.cas.cn [State Key Laboratory for Oxo Synthesis & Selective Oxidation, and National Engineering Research Center for Fine Petrochemical Intermediates, Lanzhou Institute of Chemical Physics, CAS, Lanzhou 730000 (China)

    2016-12-30

    Highlights: • Thin Bi{sub 2}MoO{sub 6} nanosheets were prepared by microwave assisted ultrasonic separation. • The thin Bi{sub 2}MoO{sub 6} nanosheets could be more favorable to charge shift and separation. • The WO{sub 3}/thin Bi{sub 2}MoO{sub 6} exhibits superior photoelectric activity than WO{sub 3}/Bi{sub 2}MoO{sub 6} film. • The efficient photoelectric property results from facilitated charge separation. - Abstract: Thin Bi{sub 2}MoO{sub 6} nanosheets are obtained by a microwave-assisted ultrasonic separation process. After exfoliation, the thinner and uniform nanosheets with a thickness of about 10 nm were obtained. The exfoliated nanosheets would provide many amazing functionalities such as high electron mobility and quantum Hall effects. Therefore, thin Bi{sub 2}MoO{sub 6} supported on WO{sub 3} electrode (WO{sub 3}/thin Bi{sub 2}MoO{sub 6}) exhibits facilitated charge separation than pure WO{sub 3} film and the un-exfoliated Bi{sub 2}MoO{sub 6} nanosheets supported on WO{sub 3} electrode (WO{sub 3}/Bi{sub 2}MoO{sub 6}). As a result, WO{sub 3}/thin Bi{sub 2}MoO{sub 6} shows remarkably stable photocurrent density of 2.2 mA/cm{sup 2} at 0.8 V{sub SCE} in 0.1 M Na{sub 2}SO{sub 4} which is higher than that of that of WO{sub 3} (1.1 mA/cm{sup 2}) and WO{sub 3}/Bi{sub 2}MoO{sub 6} (1.5 mA/cm{sup 2}).

  19. Hierarchical Bi{sub 2}WO{sub 6} architectures decorated with Pd nanoparticles for enhanced visible-light-driven photocatalytic activities

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jinniu; Chen, Tianhua [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710062 (China); Lu, Hongbing, E-mail: hblu@snnu.edu.cn [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710062 (China); Yang, Zhibo; Yin, Feng; Gao, Jianzhi; Liu, Qianru [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710062 (China); Tu, Yafang [Department of Physics, Institute for Interdisciplinary Research, Jianghan University, Wuhan, 430056 (China)

    2017-05-15

    Highlights: • A new kind of Pd decorated Bi{sub 2}WO{sub 6} hierarchical microarchitecture was synthesized. • Pd nanoparticles remarkably improved the photocatalytic activity of Bi{sub 2}WO{sub 6}. • The photo-generated holes and ·O{sub 2}{sup −} played a crucial role in the degradation of RhB. • The photocatalytic enhancement mechanism of the Pd-Bi{sub 2}WO{sub 6} composites was proposed. - Abstract: A new kind of hierarchical Pd-Bi{sub 2}WO{sub 6} architecture decorated with different molar ratios of Pd to Bi, has been fabricated by a hydrothermal process, followed by a chemical deposition method. The photocatalytic activities of the pure Bi{sub 2}WO{sub 6} and Pd-Bi{sub 2}WO{sub 6} nanocatalyst were examined in the degradation of Rhodamine B (RhB) dyes and phenol under visible light. The photocatalytic results showed that the Pd-Bi{sub 2}WO{sub 6} nanocomposites possessed observably enhanced photocatalytic activities. Particularly, the 2.0% Pd loaded Bi{sub 2}WO{sub 6} had the highest photocatalytic activity, exhibiting a nearly complete degradation of 30 mg/L RhB and 10 mg/L phenol within only 50 and 60 min, respectively. In addition, the trapping experiment results indicated that the photo-generated holes (h{sup +}) and ·O{sub 2}{sup −} played a crucial role in the degradation of RhB. According to the experimental results, the photocatalytic degradation mechanism of Pd-Bi{sub 2}WO{sub 6} was also proposed. The enhanced photocatalytic activities were ascribed to the combined effects of the highly efficient separation of electrons and holes, improved visible light utilization and increased BET specific surface areas of the Pd-Bi{sub 2}WO{sub 6} nanocomposites.

  20. WO3 Nanofiber-Based Biomarker Detectors Enabled by Protein-Encapsulated Catalyst Self-Assembled on Polystyrene Colloid Templates.

    Science.gov (United States)

    Choi, Seon-Jin; Kim, Sang-Joon; Cho, Hee-Jin; Jang, Ji-Soo; Lin, Yi-Min; Tuller, Harry L; Rutledge, Gregory C; Kim, Il-Doo

    2016-02-17

    A novel catalyst functionalization method, based on protein-encapsulated metallic nanoparticles (NPs) and their self-assembly on polystyrene (PS) colloid templates, is used to form catalyst-loaded porous WO3 nanofibers (NFs). The metallic NPs, composed of Au, Pd, or Pt, are encapsulated within a protein cage, i.e., apoferritin, to form unagglomerated monodispersed particles with diameters of less than 5 nm. The catalytic NPs maintain their nanoscale size, even following high-temperature heat-treatment during synthesis, which is attributed to the discrete self-assembly of NPs on PS colloid templates. In addition, the PS templates generate open pores on the electrospun WO3 NFs, facilitating gas molecule transport into the sensing layers and promoting active surface reactions. As a result, the Au and Pd NP-loaded porous WO3 NFs show superior sensitivity toward hydrogen sulfide, as evidenced by responses (R(air)/R(gas)) of 11.1 and 43.5 at 350 °C, respectively. These responses represent 1.8- and 7.1-fold improvements compared to that of dense WO3 NFs (R(air)/R(gas) = 6.1). Moreover, Pt NP-loaded porous WO3 NFs exhibit high acetone sensitivity with response of 28.9. These results demonstrate a novel catalyst loading method, in which small NPs are well-dispersed within the pores of WO3 NFs, that is applicable to high sensitivity breath sensors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Electron microscopy analyses and electrical properties of the layered Bi{sub 2}WO{sub 6} phase

    Energy Technology Data Exchange (ETDEWEB)

    Taoufyq, A. [Institut Matériaux Microélectronique et Nanosciences de Provence, IM2NP, UMR CNRS 7334, Université du Sud Toulon-Var, BP 20132, 83957, La Garde Cedex (France); Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir, Maroc (Morocco); Département d‘Études des Réacteurs, Laboratoire Dosimétrie Capteurs Instrumentation, CEA Cadarache (France); Société CESIGMA—Signals and Systems, 1576 Chemin de La Planquette, F 83 130 LA GARDE (France); Ait Ahsaine, H. [Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir, Maroc (Morocco); Patout, L. [Institut Matériaux Microélectronique et Nanosciences de Provence, IM2NP, UMR CNRS 7334, Université du Sud Toulon-Var, BP 20132, 83957, La Garde Cedex (France); Benlhachemi, A.; Ezahri, M. [Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir, Maroc (Morocco); and others

    2013-07-15

    The bismuth tungstate Bi{sub 2}WO{sub 6} was synthesized using a classical coprecipitation method followed by a calcination process at different temperatures. The samples were characterized by X-ray diffraction, simultaneous thermogravimetry and differential thermal analysis (TGA/DTA), scanning and transmission electron microscopy (SEM, TEM) analyses. The Rietveld analysis and electron diffraction clearly confirmed the Pca2{sub 1} non centrosymmetric space group previously proposed for this phase. The layers Bi{sub 2}O{sub 2}{sup 2+} and WO{sub 4}{sup 2−} have been directly evidenced from the HRTEM images. The electrical properties of Bi{sub 2}WO{sub 6} compacted pellets systems were determined from electrical impedance spectrometry (EIS) and direct current (DC) analyses, under air and argon, between 350 and 700 °C. The direct current analyses showed that the conduction observed from EIS analyses was mainly ionic in this temperature range, with a small electronic contribution. Electrical change above the transition temperature of 660 °C is observed under air and argon atmospheres. The strong conductivity increase observed under argon is interpreted in terms of formation of additional oxygen vacancies coupled with electron conduction. - Graphical abstract: High resolution transmission electron microscopy: inverse fast Fourier transform giving the layered structure of the Bi{sub 2}WO{sub 6} phase, with a representation of the cell dimensions (b and c vectors). The Bi{sub 2}O{sub 2}{sup 2+} and WO{sub 4}{sup 2−} sandwiches are visible in the IFFT image. - Highlights: • Using transmission electron microscopy, we visualize the layered structure of Bi{sub 2}WO{sub 6}. • Electrical analyses under argon gas show some increase in conductivity. • The phase transition at 660 °C is evidenced from electrical modification.

  2. World Register of marine Cave Species (WoRCS: a new Thematic Species Database for marine and anchialine cave biodiversity

    Directory of Open Access Journals (Sweden)

    Vasilis Gerovasileiou

    2016-09-01

    Full Text Available Scientific exploration of marine cave environments and anchialine ecosystems over recent decades has led to outstanding discoveries of novel taxa, increasing our knowledge of biodiversity. However, biological research on underwater caves has taken place only in a few areas of the world and relevant information remains fragmented in isolated publications and databases. This fragmentation makes assessing the conservation status of marine cave species especially problematic, and this issue should be addressed urgently given the stresses resulting from planned and rampant development in the coastal zone worldwide. The goal of the World Register of marine Cave Species (WoRCS initiative is to create a comprehensive taxonomic and ecological database of known species from marine caves and anchialine systems worldwide and to present this as a Thematic Species Database (TSD of the World Register of marine Species (WoRMS. WoRCS will incorporate ecological data (e.g., type of environment, salinity regimes, and cave zone as well as geographical information on the distribution of species in cave and anchialine environments. Biodiversity data will be progressively assembled from individual database sources at regional, national or local levels, as well as from literature sources (estimate: >20,000 existing records of cave-dwelling species scattered in several databases. Information will be organized in the WoRCS database following a standard glossary based on existing terminology. Cave-related information will be managed by the WoRCS thematic editors with all data dynamically linked to WoRMS and its team of taxonomic editors. In order to mobilize data into global biogeographic databases, a Gazetteer of the Marine and Anchialine Caves of the World will be established. The presence records of species could be eventually georeferenced for submission to the Ocean Biogeographic Information System (OBIS and constitute an important dataset for biogeographical and

  3. Photoelectrocatalytic degradation of diazo dyes on nanostructured WO{sub 3} electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Hepel, Maria [Department of Chemistry, State University of New York at Potsdam, Potsdam, NY 13676 (United States)]. E-mail: hepelmr@potsdam.edu; Hazelton, Sandra [Department of Chemistry, State University of New York at Potsdam, Potsdam, NY 13676 (United States)

    2005-09-05

    Photoelectrocatalytic degradation of Remazol Black B (RBB) dye in aqueous solutions was investigated. The degradation was carried out on a highly efficient n-WO{sub 3} photoelectrode, which was synthesized by electrochemical processing. Effects of various synthesis and post-treatment conditions were investigated using electrochemical techniques and AFM imaging. Photocurrent measurements have shown that Butler-Gartner equation is fulfilled for n-WO{sub 3} films, which allowed us to determine the flat-band potential (E {sub fb} = 0.35 V versus Ag/AgCl, for pH = 0). The WO{sub 3} film electrode was found to be a better photelectrocatalyst than TiO{sub 2} with similar AFM surface roughness. Kinetic measurements of photoelectrocatalytic RBB degradation have shown that a generalized Langmuir-Hinshelwood model applies to the system, leading to the overall rate constant k' = 1.1 x 10{sup -9} mol cm{sup -2} s{sup -1}, with RBB adsorption equilibrium constant K = 3.35 x 10{sup 4} mol{sup -1} L and Gibbs free energy of adsorption {delta}G deg. = -6.16 kcal/mol (-25.8 kJ/mol). In mechanistic considerations of possible lines of oxidative attack on RBB, we looked at electrolyte composition and properties of electronic structure of RBB, by utilizing quantum mechanical calculations of molecular orbitals. The ab initio SCF Hartree-Fock calculations of molecular orbitals were carried out to evaluate most vulnerable areas of RBB molecule for electrophilic and nucleophilic attacks, as well as for a direct charge transfer oxidation process. Several electronic properties were mapped onto the total electron density surface and analyzed to reveal initial reaction pathways for oxidative degradation of RBB.

  4. Time decay and photoluminescence measurement of PbWO4 crystal

    International Nuclear Information System (INIS)

    Baylac, M.

    1997-09-01

    This report presented the experimental characterization of the PbWO 4 crystals that we will be used for the photon detector of the Compton polarimeter at the Jefferson laboratory. We could draw 3 main features from this study. The transmission rate of the crystals is about 60 % in the scintillation wavelength region. From the decay time analysis, we deduced 3 decay components of the PbWO 4 , predicted by other measurements: τ 1 ∼5 ns, τ 2 ∼20 ns, τ 3 ∼100 ns, taking respectively 26 %, 30 % and 4 % of the total light amplitude emitted by the crystals. Moreover, we showed the existence of a fourth decay constant (τ 4 ∼1μs) taking 40 % of the total quantity of light which is responsible for the bad precision on the third constant determination. We could not characterize this component accurately because of the limited time range of the recordings. To improve the determination of the super-slow component, we need to perform the measurements again on a longer time scale, on the order of a few microseconds. We eventually measured the light yield of the PbWO 4 crystals. With a first analysis, we found about 3.5 photoelectrons per MeV whereas the constructors note gave about 10. We then reduced the light loss in the experimental set up by wrapping the last open end of the crystal. The results were slightly improved. Eventually, we increased the recording time, to take account the super-low decay, and found that the crystals yield about 6 photoelectrons per MeV which is still less than predicted. (author)

  5. [Growth of codoped CdWO4 crystals by Bridgman method and their optical spectra].

    Science.gov (United States)

    Yu, Can; Xia, Hai-Ping; Wang, Dong-Jie; Chen, Hong-Bing

    2011-09-01

    The CdWO4 crystals with good quality in the size of Phi25 mm x 120 mm, doped with Co in 0.5% molar fraction in the raw composition, were grown by the Bridgman method by taking -70 degrees C x cm(-1) of solid-liquid interface and -0.50 mm x h(-1) growth rate. The crystal presents transparence and deep blue. The X-ray diffraction (XRD) was used to characterize the crystals. Three absorption peaks at 518, 564 and 655 nm respectively, which are attributed to the overlapping of 4 T1 (4F) --> 4A2 (4F) and 4 T1 (4F) --> 4 T1 (4P) of Co2+ octahedrons, and a wide band centered at 1 863 nm, which is attributed to 4Ti (4F) --> 4 T2 (4F), was observed. The absorption results indicated that the Co ions presented +2 valence in crystal and located within the distorted oxygen octahedrons. The crystal-field parameter D(q) and the Racah parameter B were estimated to be 990 and 726.3 cm(-1) respectively based on the absorption spectra. A fluorescence emission at 778 nm (4T1 (4P) --> 4 T1 (4F)) for codoped CdWO4 crystals was observed under excitation by 520 nm light. It can be deduced from the changes in absorption and emission intensity of different parts of crystal that the concentration of Co2+ ion in crystal increased along growing direction and the effective distribution coefficient of Co2+ ion in CdWO4 crystal is less than 1.

  6. Europium doping in monoclinic KYb(WO{sub 4}){sub 2} crystal

    Energy Technology Data Exchange (ETDEWEB)

    Loiko, P.A. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n., Tarragona, Spain E-43007 (Spain); Center for Optical Materials and Technologies (COMT), Belarusian National Technical University, 65/17 Nezavisimosti Ave., Minsk 220013 (Belarus); Vilejshikova, E.V. [Center for Optical Materials and Technologies (COMT), Belarusian National Technical University, 65/17 Nezavisimosti Ave., Minsk 220013 (Belarus); Mateos, X., E-mail: xavier.mateos@urv.cat [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n., Tarragona, Spain E-43007 (Spain); Serres, J.M. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n., Tarragona, Spain E-43007 (Spain); Dunina, E.B.; Kornienko, A.A. [Vitebsk State Technological University, 72 Moskovskaya Ave., Vitebsk 210035 (Belarus); Yumashev, K.V. [Center for Optical Materials and Technologies (COMT), Belarusian National Technical University, 65/17 Nezavisimosti Ave., Minsk 220013 (Belarus); Aguiló, M.; Díaz, F. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n., Tarragona, Spain E-43007 (Spain)

    2017-03-15

    We report on a detailed spectroscopic study of Eu{sup 3+} ions in the monoclinic KYb(WO{sub 4}){sub 2} crystal. The polarized room and low-temperature absorption spectra are measured. The maximum σ{sub abs} corresponding to the {sup 7}F{sub 1} → {sup 5}D{sub 1} transition is 1.32×10{sup –20} cm{sup 2} at 534.2 nm with a bandwidth of 0.7 nm (for E||N{sub m}). The Stark sub-levels of the excited mulitplets are determined. A Judd-Ofelt analysis is applied to the Eu{sup 3+}:KYb(WO{sub 4}){sub 2} crystal to determine the probability of spontaneous transitions, radiative lifetimes and luminescence branching ratios. Within the strong configuration interaction (SCI) approximation, the intensity parameters are Ω{sub 2}=4.757, Ω{sub 4}=2.295, Ω{sub 6}=1.644 [10{sup –20} cm{sup 2}] and Δ{sub f}=50160 cm{sup –1}. The radiative lifetime of the {sup 5}D{sub 0} state is 351 µs. The maximum stimulated-emission cross-section corresponding to the {sup 7}F{sub 1} → {sup 5}D{sub 1} transition is 1.44×10{sup –20} cm{sup 2} at 703.2 nm (for E||N{sub m}). Under UV excitation, the Eu{sup 3+}:KYb(WO{sub 4}){sub 2} crystal provides intense red photoluminescence with CIE coordinates, x=0.675, y=0.325.

  7. Acrylonitrile butadiene rubber (NBR)/manganous tungstate (MnWO4) nanocomposites: Characterization, mechanical and electrical properties

    Science.gov (United States)

    Ramesan, M. T.; Abdu Raheem V., P.; Jayakrishnan, P.; Pradyumnan, P. P.

    2014-10-01

    Nanocomposites of NBR with manganous-tungstate nanoparticles were prepared through vulcanization process. The extent of interaction of nanoparticles with the polymer was studied by FTIR, SEM, XRD, TGA and AC conductivity. FTIR and XRD ascertain the interaction of NBR with MnWO4 nanoparticles. SEM analysis established that the nanopartilces were well dispersed in the macromolecular chain of NBR. The mechanical properties of the nanocomposites were studied as a function of filler loading. The nanocomposites exhibited enhanced thermal stability as seen in TGA. Conductivity and dielectric properties of nanocomposites increase with increase in concentration of MnWO4 nanoparticles (7phr) and thereafter the value decreases.

  8. UV-Vis optoelectronic properties of α-SnWO4: A comparative experimental and density functional theory based study

    KAUST Repository

    Ziani, Ahmed

    2015-09-03

    We report a combined experimental and theoretical study on the optoelectronic properties of α-SnWO4 for UV-Vis excitation. The experimentally measured values for thin films were systematically compared with high-accuracy density functional theory and density functional perturbation theory using the HSE06 functional. The α-SnWO4 material shows an indirect bandgap of 1.52 eV with high absorption coefficient in the visible-light range (>2 × 105 cm−1). The results show relatively high dielectric constant (>30) and weak diffusion properties (large effective masses) of excited carriers.

  9. Influence of the reactor irradiation on the radiation-optical features of the PbWO4:La scintillation crystals

    International Nuclear Information System (INIS)

    Ashurov, M.Kh.; Ismoilov, Sh.Kh.; Khatamov, K.; Gasanov, Eh.M.; Rustamov, I.R.

    2001-01-01

    Within an International LHC project the lead tungstates (PbWO 4 ) scintillation crystals radiation stability activated by La ions was carried out. In the 400-700 nm length range the transmission spectra were measured on the different parts of the standard PbWO 4 :La crystals. The spectra were measured before and after irradiation by both fast neutrons and γ-radiation. On the base of obtained data the contribution of γ-quanta and neutrons in the radiation-induced losses value of optical radiation in the active media of the electromagnetic colorimeter was estimated

  10. Luminescence and thermoluminescence properties of Sr{sub 3}WO{sub 6}:Eu{sup 3+} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Emen, F.M., E-mail: femen106@gmail.com [Department of Chemistry, Faculty of Arts and Science, Mehmet Akif Ersoy University, TR 15030, Burdur (Turkey); Altinkaya, R. [Department of Chemistry, Faculty of Arts and Science, Mersin University, TR 33343, Mersin (Turkey)

    2013-02-15

    Sr{sub 3-x}WO{sub 6}:xEu{sup 3+} (x varies from 0.01 to 0.06) phosphors have been prepared at high temperature by the solid-state method. The crystal structure of Sr{sub 2.95}WO{sub 6}:0.05Eu{sup 3+} phosphor has been determined as a triclinic P-1 space group with a=8.3608 (19) A, b=8.2903 (24) A, c=8.2145 (23) A, {alpha}=89.79 (3){sup Degree-Sign }, {beta}=89.82 (3){sup Degree-Sign }, and {gamma}=89.753 (22){sup Degree-Sign }. The excitation spectrum of Sr{sub 2.95}WO{sub 6}:0.05Eu{sup 3+} phosphor reveals five excitation bands: one is assigned to the charge-transfer (CTLM) band of Sr{sub 3}WO{sub 6} host at 307 nm, and another is assigned to intra-4f transitions between 393 nm and 600 nm. The emission spectrum of Sr{sub 2.95}WO{sub 6}:0.05Eu{sup 3+} phosphor exhibits a series of emission bands, which are attributed to the {sup 5}D{sub 0}{yields}{sup 7}F{sub j} (j=0-4) transitions of Eu{sup 3+} ions. The luminescence studies revealed that the Eu{sup 3+} ions show high luminescent efficiency in emitting red light at 616 nm. The thermoluminescence glow curve shows one dominant glow peak observed at 56 Degree-Sign C which is related to the defects at shallow trap depth. The trap parameters mainly activation energy (E{sub a}) and the order of the kinetics (b) were evaluated by using Rasheedy's three points method (TPM). - Highlights: Black-Right-Pointing-Pointer The Sr{sub 3}WO{sub 6}:Eu{sup 3+} phosphor was prepared by using conventional ceramic method. Black-Right-Pointing-Pointer The diffraction peaks of phosphor have been indexed to triclinic system. Black-Right-Pointing-Pointer The emission peak at 616 nm belongs to {sup 5}D{sub 0}{yields}{sup 7}F{sub 2} electric dipole transitions of Eu{sup 3+}. Black-Right-Pointing-Pointer The emission band of WO{sub 6} and excitation bands of Eu{sup 3+} are overlapping each other. Black-Right-Pointing-Pointer The energy transfer from WO{sub 6} groups to the Eu{sup 3+} ions occurs under the UV excitation.

  11. Study of multiferroic properties of Bi2Fe2WO9 ceramic for device application

    OpenAIRE

    Jyoshna Rout; R. N. P. Choudhary

    2016-01-01

    The Bi2Fe2WO9 ceramic was prepared using a standard solid-state reaction technique. Preliminary analysis of X-ray diffraction pattern revealed the formation of single-phase compound with orthorhombic crystal symmetry. The surface morphology of the material captured using scanning electron microscope (SEM) exhibits formation of a densely packed microstructure. Comprehensive study of dielectric properties showed two anomalies at 200∘C and 450∘C: first one may be related to magnetic whereas seco...

  12. The system NaVO3-Na2WO4-Na2W2O7

    International Nuclear Information System (INIS)

    Kazanbekov, V.R.; Gasanaliev, A.M.; Kazanbekov, R.G.

    1994-01-01

    Phase diagrams of sodium metavanadate-sodium ditungstate, sodium metavanadate-sodium tungstate systems and surface of primary crystallization of sodium metavabadate-sodium tungstate-sodium ditungstate system were studied. The system sodium metavanadate-sodium ditungstate is eutectic one. Compound NaVO 3 x2Na 2 WO 4 is formed in solid state in sodium metavanadate-sodium tungstate system. Liquidus surface of sodium metavanadate-sodium tungstate-sodium ditungstate is presented by three crystallization fields of initial components. Composition and melting point of ternary eutectics are determined

  13. Investigation of water content in electrolyte solution on electrochromic properties of WO3 thin Films

    Directory of Open Access Journals (Sweden)

    Zahra Abadi

    2017-05-01

    Full Text Available Tungsten oxide thin films were prepared by a cathodic electrodeposition method at -0.450 mV in order to investigate how water content affects their electrochromic properties. FESEM images exhibit that WO3 thin films consist of 65 nm uniform grains. Thin Films were electrochemically investigated in 0.1M LiClO4 in propylene carbonate electrolyte with and without 5vol% water content by cyclic voltammetry and chronoamperometry. The results indicate that tungsten oxide thin films exhibit faster switching time between coloration and bleaching states and also higher coloration efficiency in hydrated electrolyte.  

  14. WO.sub.3./sub. thin films prepared by sedimentation and plasma sputtering

    Czech Academy of Sciences Publication Activity Database

    Olejníček, Jiří; Brunclíková, Michaela; Kment, Š.; Hubička, Zdeněk; Kmentová, N.; Kšírová, Petra; Čada, Martin; Zlámal, M.; Krýsa, J.

    2017-01-01

    Roč. 318, Jun (2017), s. 281-288 ISSN 1385-8947 R&D Projects: GA TA ČR(CZ) TF01000084; GA ČR(CZ) GA15-00863S; GA TA ČR TA03010743; GA ČR GAP108/12/2104 Institutional support: RVO:68378271 Keywords : WO 3 * thin films * water splitting * pulsed magnetron sputtering * sedimentation * photo-electro-chemistry Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 6.216, year: 2016

  15. Surface quality inspection of PbWO4 crystals by grazing incidence X-ray diffraction

    International Nuclear Information System (INIS)

    Mengucci, P.; Di Cristoforo, A.; Lebeau, M.; Majni, G.; Paone, N.; Pietroni, P.; Rinaldi, D.

    2005-01-01

    High-quality scintillating crystals are required for applications in radiographic systems and high-energy physics detectors to achieve the specified optical properties. In order to study the state of the single crystals surface we propose the use of the grazing incidence X-ray diffraction (GID) technique. This technique allows performing a depth profiling of the sample by changing the incidence angle of the X-ray beam with respect to the sample surface. In this work, two samples of a large PbWO 4 (PWO) single crystal exhibiting different surface roughness values have been studied. Results have shown that GID is a suitable technique for surface quality inspection

  16. Semiconducting WO.sub.3./sub. thin films prepared by pulsed reactive magnetron sputtering

    Czech Academy of Sciences Publication Activity Database

    Brunclíková, M.; Hubička, Zdeněk; Kment, Štěpán; Olejníček, Jiří; Čada, Martin; Kšírová, Petra; Krýsa, J.

    2015-01-01

    Roč. 41, č. 12 (2015), s. 9259-9266 ISSN 0922-6168. [Pannonian Symposium on Catalysis /12./. Třešť, 16.09.2014-20.09.2014] R&D Projects: GA ČR GAP108/12/2104; GA MŠk LH12043 Grant - others:AVČR(CZ) M100101215 Institutional support: RVO:68378271 Keywords : WO 3 * water splitting * HIPIMS * photoanodes Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.833, year: 2015

  17. Inductive effect of poly(vinyl pyrrolidone) on morphology and photocatalytic performance of Bi{sub 2}WO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qiang; Chen, Jinxing; Xie, Yunyun; Wang, Mozhen; Ge, Xuewu, E-mail: xwge@ustc.edu.cn

    2016-04-15

    Graphical abstract: - Highlights: • PVP molecular chains will induce the assembly of the primary Bi{sub 2}WO{sub 6} nanosheets. • The assembly of primary Bi{sub 2}WO{sub 6} nanosheets forms various 3D topological structure. • Sheet-like, flower-like, red-blood-cell-like and square-pillar-like Bi{sub 2}WO{sub 6} were formed. • Bi{sub 2}WO{sub 6} formed at low concentration or molecular weight of PVP has better activity. - Abstract: Bi{sub 2}WO{sub 6} has great potential applications in the field of photocatalyst due to its excellent visible-light photocatalytic performance. This work studied the detailed morphological evolution of Bi{sub 2}WO{sub 6} particles synthesized in a simple hydrothermal system induced by the stabilizer poly(vinyl pyrrolidone) (PVP). The XRD and HRTEM results show PVP would not change the crystal structure of Bi{sub 2}WO{sub 6}, but the distribution of PVP on the initially formed Bi{sub 2}WO{sub 6} nanosheets will induce the crystal growth, resulting in a distinct morphology evolution of Bi{sub 2}WO{sub 6} with the increase of the concentration of PVP. At the same time, with the increase of the molecular weight of PVP, the morphology of Bi{sub 2}WO{sub 6} varied from simple sheet-like (S-BWO) to some complicated morphology, such as flower-like (F-BWO), red blood cell-like (B-BWO), and square-pillar-like (SP-BWO). The photocatalytic performances of Bi{sub 2}WO{sub 6} with various morphologies on the decomposition of RhB under visible light irradiation reveal that S-BWO has the best photocatalytic performance, while SP-BWO has the worst. This work not only gives the explanation of the inductive effect of PVP molecular chains on the morphological formation of Bi{sub 2}WO{sub 6} particles, but also provides the controllable way to the preparation of Bi{sub 2}WO{sub 6} with various morphologies taking advantage of the stabilizer PVP.

  18. Comparative investigation of the Ti and Mo additives influence on the opto-electronic properties of the spray deposited WO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Manceriu, Laura Maria, E-mail: manceriu.laura@gmail.com [CNRS, Université de Bordeaux, ICMCB, 87 Avenue du Dr. Albert Schweitzer, F-33608 Pessac (France); The RTD Dept. Renewable Energy Systems and Recycling, University of Transilvania Brasov, Eroilor 29, 500036 Brasov (Romania); Rougier, Aline [CNRS, Université de Bordeaux, ICMCB, 87 Avenue du Dr. Albert Schweitzer, F-33608 Pessac (France); Duta, Anca, E-mail: a.duta@unitbv.ro [The RTD Dept. Renewable Energy Systems and Recycling, University of Transilvania Brasov, Eroilor 29, 500036 Brasov (Romania)

    2015-05-05

    Highlights: • Ti and Mo–WO{sub 3} thin films were obtained by spray pyrolysis. • Morphology and structure changes related to solution surface tension modification. • FTO/WO{sub 3} junction parameters dependent on WO{sub 3} layer morphology and structure. • Flat band potential and series resistance varied with cation doping. • Ad(de)sorption of oxygen/water during annealing and cooling influence conductivity. - Abstract: In this paper we compare the optical and electrical properties of the WO{sub 3} thin films containing 2, 5 and 10 at.% of Ti and Mo additives, deposited by spray pyrolysis. The influence of the type and additive concentration on the nanostructure, topography and composition of the WO{sub 3} layers are mainly related to the surface tension energy changes, and further correlated with the (photo)electrical and optical properties. The FTO/WO{sub 3} junction through its characteristic, namely barrier height, ideality factor, flat band potential, and series resistance, served as a tool for associating the before mentioned characteristics. The morphology of the WO{sub 3} thin films densifies and the roughness is reduced with increasing Ti and Mo concentration, in good agreement with solution surface tension reduction. WO{sub 3} based films exhibit a p-type semiconducting behavior, as confirmed also by the Mott–Schottky analysis, with a lower p-type conductivity for the Ti–WO{sub 3} films, as higher number of oxygen vacancies are generated by Ti addition. Changes in conductivity are mainly attributed to the oxygen vacancies concentration evolution at the film surface due to oxygen/water adsorption. For heavily doped WO{sub 3} thin films the contribution of these surface processes to the overall conductivity is reduced since surface reactivity is lost by densification. As opposed to Ti-doping which has a detrimental effect on layers structure, Mo addition, even in high concentrations, has a positive effect on layers crystallinity; hence

  19. Photothermal ablation cancer therapy using homogeneous CsxWO3 nanorods with broad near-infra-red absorption

    Science.gov (United States)

    Guo, Chongshen; Yin, Shu; Yu, Haijun; Liu, Shaoqin; Dong, Qiang; Goto, Takehiro; Zhang, Zhiwen; Li, Yaping; Sato, Tsugio

    2013-06-01

    Recently, photothermal ablation therapy (PTA) employing near-infrared radiation (NIR) has been extensively investigated as an emerging modality for cancer management. However, the clinical translation of this promising approach is limited by the lack of PTA agents with broad NIR absorption, low cost and high photothermal conversion efficiency. Herein, we have developed PEGylated homogeneous CsxWO3 nanorods (a mean size ~69.3 nm × 12.8 nm) with broad photo-absorption (780-2500 nm) as a novel NIR absorbent for PTA treatment of human cancer. The prepared CsxWO3 nanocrystals displayed strong near-infrared optical absorption with a high molar extinction coefficient (e.g. 4.8 × 1010 M-1 cm-1 at 980 nm), thus generated significant amounts of heat upon excitation with near-infrared light. The PTA study in two human carcinoma cell lines (i.e. A549 lung cancer cells and HeLa ovarian cancer cells) demonstrated that CsxWO3 nanorods can efficiently cause cell death via hyperthermia induced lysosome destruction, cytoskeleton protein degradation, DNA damage and thereafter cellular necrosis or apoptosis. Our study also confirmed the migration of healthy cells migrated from unirradiated areas to dead cell cycle, which is essential for tissue reconstruction and wound healing after photodestruction of tumor tissue. The prompted results reported in the current study imply the promising potential of CsxWO3 nanorods for application in PTA cancer therapy.Recently, photothermal ablation therapy (PTA) employing near-infrared radiation (NIR) has been extensively investigated as an emerging modality for cancer management. However, the clinical translation of this promising approach is limited by the lack of PTA agents with broad NIR absorption, low cost and high photothermal conversion efficiency. Herein, we have developed PEGylated homogeneous CsxWO3 nanorods (a mean size ~69.3 nm × 12.8 nm) with broad photo-absorption (780-2500 nm) as a novel NIR absorbent for PTA treatment of human

  20. Moessbauer effect study of hyperfine interaction of /sup 161/Dy and /sup 151/Eu in tungsten bronzes Dysub(0. 18) WO/sub 3/ and Eusub(0. 18) WO/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Kisynska, K

    1979-01-01

    The Moessbauer technique was used to investigate the hyperfine interaction of /sup 161/Dy and /sup 151/Eu in cubic rare earth tungsten bronzes: Dysub(0.18)WO/sub 3/ and Eusub(0.18)WO/sub 3/. Well resolved hfs spectrum was obtained at 4.2 K for Dysub(0.18)WO/sub 3/. The effective hf field approximation sufficed to interpret the spectrum. The obtained hyperfine interaction parameters were: -g/sub 0/..beta..sub(N)Hsub(eff)=(805+-19) Mc/s and e/sup 2/qQ/sub 0//4 = (506+-56) Mc/s. These results imply that ground doublet of Dy/sup +3/ ion in bronze is a Kramers doublet Vertical Bar+-15/2> with asymmetrical hyperfine tensor Asub(z) non equal to 0, Asub(x) = Asub(y) = 0 and that local crystalline field at RE metal in tungsten bronze at 4.2 K cannot be cubic. From ME absorption spectra of Eusub(0.18)WO/sub 3/ taken at 4.2 K, 78 K and 300 K the values of quadrupole interaction constants for bronze lattice and its temperature dependence were obtained. These data indicate that a phase transition from the high temperature ideal perovskite structure to a distorted one occurs in RE bronzes and that the distortion concerns the nearest tungsten-oxygen environment of RE ion.

  1. Synthesis, Analysis, and Testing of BiOBr-Bi2WO6 Photocatalytic Heterojunction Semiconductors

    Directory of Open Access Journals (Sweden)

    Xiangchao Meng

    2015-01-01

    Full Text Available In photocatalysis, the recombination of electron-hole pairs is generally regarded as one of its most serious drawbacks. The synthesis of various composites with heterojunction structures has increasingly shed light on preventing this recombination. In this work, a BiOBr-Bi2WO6 photocatalytic heterojunction semiconductor was synthesized by the facile hydrothermal method and applied in the photocatalytic degradation process. It was determined that both reaction time and temperature significantly affected the crystal structure and morphologies of the photocatalysts. BiOBr (50 at%-Bi2WO6 composites were prepared under optimum synthesis conditions (120°C for 6 h and by theoretically analyzing the DRS results, it was determined that they possessed the suitable band gap (2.61 eV to be stimulated by visible-light irradiation. The photocatalytic activities of the as-prepared photocatalysts were evaluated by the degradation of Rhodamine B (RhB under visible-light irradiation. The experimental conditions, including initial concentration, pH, and catalyst dosage, were explored and the photocatalysts in this system were proven stable enough to be reused for several runs. Moreover, the interpreted mechanism of the heterojunction enhancement effect proved that the synthesis of a heterojunction structure provided an effective method to decrease the recombination rate of the electron-hole pairs, thereby improving the photocatalytic activity.

  2. Monolayered Bi2WO6 nanosheets mimicking heterojunction interface with open surfaces for photocatalysis

    Science.gov (United States)

    Zhou, Yangen; Zhang, Yongfan; Lin, Mousheng; Long, Jinlin; Zhang, Zizhong; Lin, Huaxiang; Wu, Jeffrey C.-S.; Wang, Xuxu

    2015-09-01

    Two-dimensional-layered heterojunctions have attracted extensive interest recently due to their exciting behaviours in electronic/optoelectronic devices as well as solar energy conversion systems. However, layered heterojunction materials, especially those made by stacking different monolayers together by strong chemical bonds rather than by weak van der Waal interactions, are still challenging to fabricate. Here the monolayer Bi2WO6 with a sandwich substructure of [BiO]+-[WO4]2--[BiO]+ is reported. This material may be characterized as a layered heterojunction with different monolayer oxides held together by chemical bonds. Coordinatively unsaturated Bi atoms are present as active sites on the surface. On irradiation, holes are generated directly on the active surface layer and electrons in the middle layer, which leads to the outstanding performances of the monolayer material in solar energy conversion. Our work provides a general bottom-up route for designing and preparing novel monolayer materials with ultrafast charge separation and active surface.

  3. In situ growth of metal particles on 3D urchin-like WO3 nanostructures.

    Science.gov (United States)

    Xi, Guangcheng; Ye, Jinhua; Ma, Qiang; Su, Ning; Bai, Hua; Wang, Chao

    2012-04-18

    Metal/semiconductor hybrid materials of various sizes and morphologies have many applications in areas such as catalysis and sensing. Various organic agents are necessary to stabilize metal nanoparticles during synthesis, which leads to a layer of organic compounds present at the interfaces between the metal particles and the semiconductor supports. Generally, high-temperature oxidative treatment is used to remove the organics, which can extensively change the size and morphology of the particles, in turn altering their activity. Here we report a facile method for direct growth of noble-metal particles on WO(3) through an in situ redox reaction between weakly reductive WO(2.72) and oxidative metal salts in aqueous solution. This synthetic strategy has the advantages that it takes place in one step and requires no foreign reducing agents, stabilizing agents, or pretreatment of the precursors, making it a practical method for the controlled synthesis of metal/semiconductor hybrid nanomaterials. This synthetic method may open up a new way to develop metal-nanoparticle-loaded semiconductor composites. © 2012 American Chemical Society

  4. Superior acidic catalytic activity and stability of Fe-doped HTaWO6 nanotubes

    KAUST Repository

    Liu, He

    2017-07-26

    Fe-doped HTaWO6 (H1-3xFexTaWO6, x = 0.23) nanotubes as highly active solid acid catalysts were prepared via an exfoliation-scrolling-exchange process. The specific surface area and pore volume of undoped nanotubes (20.8 m2 g-1, 0.057 cm3 g-1) were remarkably enhanced through Fe3+ ion-exchange (>100 m2 g-1, 0.547 cm3 g-1). Doping Fe ions into the nanotubes endowed them with improved thermal stability due to the stronger interaction between the intercalated Fe3+ ions and the host layers. This interaction also facilitated the preservation of effective Brønsted acid sites and the generation of new acid sites. The integration of these functional roles resulted in Fe-doped nanotubes with high acidic catalytic activities in the Friedel-Crafts alkylation of anisole and the esterification of acetic acid. Facile accessibility to active sites, generation of effective Brønsted acid sites, high stability of the tubular structure and strong acid sites were found to synergistically contribute to the excellent acidic catalytic efficiency. Additionally, the activity of cycled nanocatalysts can be easily recovered through annealing treatment.

  5. Effect of W/O Emulsion Fuel Properties on Spray Combustion

    Science.gov (United States)

    Ida, Tamio; Fuchihata, Manabu; Takeda, Shuuco

    This study proposes a realizable technology for an emulsion combustion method that can reduce environmental loading. This paper discusses the effect on spray combustion for W/O emulsion fuel properties with an added agent, and the ratio between water and emulsifier added to a liquid fuel. The addition of water or emulsifier to a liquid fuel affected the spray combustion by causing micro-explosions in the flame due to geometric changes in the sprayed flame and changes to the temperature distribution. Experimental results revealed that the flame length shortened by almost 40% upon the addition of the water. Furthermore, it was found that water was effective in enhancing combustion due to its promoting micro-explosions. Results also showed that when the emulsifier was added to the spray flame, the additive burned in the flame's wake, producing a bright red flame. The flame length was observed to be long as a result. The micro-explosion phenomenon, caused by emulsifier dosage differences, was observed using time-dependent images at a generated frequency and an explosion scale with a high-speed photography method. Results indicated that the micro-explosion phenomenon in the W/O emulsion combustion method effectively promoted the combustion reaction and suppressed soot formation.

  6. Neutron Powder Diffraction Studies of Ca2-xSrxCoWO6 Double Perovskites

    International Nuclear Information System (INIS)

    Zhou, Qingdi; Kennedy, Brendan; Elcombe, Margaret

    2005-01-01

    Full text: A series of double perovskite compounds of A 2-x Sr x CoWO 6 (A = Ca, Ba) were synthesized and the room- and variable-temperature structural phase transitions have been studied by synchrotron and neutron powder diffraction techniques. These studies demonstrated that the symmetry increases as the average size of the A-site cation increases. These transitions are associated with the gradual reduction and ultimately removal of the octahedral tiles of the BO 6 octahedra. Temperature dependent structural studies have been undertaken for selected samples. The transition to cubic is continuous in the three Ca doped samples studied as a function of temperature, Ca 2-x Sr x CoWO 6 x = 1.8, 1.7, 1.6, however in each case analysis of the spontaneous strain shows the transition to be tricritical rather than second order in nature. Where observed the temperature induced P2 1 /n to I4/m transition is first order as required by symmetry. (authors)>>>>

  7. Renewable energy production by photoelectrochemical oxidation of organic wastes using WO{sub 3} photoanodes

    Energy Technology Data Exchange (ETDEWEB)

    Raptis, Dimitrios [Department of Chemical Engineering, University of Patras, 26500 Patras (Greece); Dracopoulos, Vassilios [FORTH/ICE-HT, P.O. Box 1414, 26504 Patras (Greece); Lianos, Panagiotis, E-mail: lianos@upatras.gr [Department of Chemical Engineering, University of Patras, 26500 Patras (Greece)

    2017-07-05

    Highlights: • Efficient nanoparticulate WO{sub 3} photoanodes. • Photoelectrocatalytic hydrogen production by consumption of organic wastes. • Photoelectrocatalytic oxidation of ethanol, glycerol or sorbitol. • Recording of hydrogen production and calculation of efficiencies. - Abstract: The present work has studied renewable hydrogen production by photoelectrocatalytic degradation of model organic substances representing biomass derived organic wastes. Its purpose was to show that renewable energy can be produced by consuming wastes. The study has been carried out by employing nanoparticulate WO{sub 3} photoanodes in the presence of ethanol, glycerol or sorbitol, i.e. three substances which are among typical biomass products. In these substances, the molecular weight and the number of hydroxyl groups increases from ethanol to sorbitol. The photocurrent produced by the cell was the highest in the presence of ethanol, smaller in the case of glycerol and further decreased in the presence of sorbitol. The photocurrent was roughly the double of that produced in the absence of an organic additive thus demonstrating current doubling phenomena. Hydrogen was produced only under illumination and was monitored at two forward bias, 0.8 and 1.6 V vs Ag/AgCl. Hydrogen production rates followed the same order as the photocurrent thus indicating that hydrogen production by reduction of protons mainly depends on the current flowing through the external circuit connecting photoanode with cathode. The maximum solar-to-hydrogen efficiency reached by the present system was 2.35%.

  8. Thickness control in electrophoretic deposition of WO3 nanofiber thin films for solar water splitting

    International Nuclear Information System (INIS)

    Fang, Yuanxing; Lee, Wei Cheat; Canciani, Giacomo E.; Draper, Thomas C.; Al-Bawi, Zainab F.; Bedi, Jasbir S.; Perry, Christopher C.; Chen, Qiao

    2015-01-01

    Graphical abstract: - Highlights: • A novel method combining electrospinning and electrophoretic deposition was established for the creation of nanostructured semiconductor thin films. • The created thin films displayed a high chemical stability with a controllable thickness. • The PEC water splitting performance of the thin films was optimized by fine-tuning the thickness of the films. • A maximum photoconversion efficiency was achieved by 18 μm nanofibrous thin films. - Abstract: Electrophoretic deposition (EPD) of ground electrospun WO 3 nanofibers was applied to create photoanodes with controlled morphology for the application of photoelectrochemical (PEC) water splitting. The correlations between deposition parameters and film thicknesses were investigated with theoretical models to precisely control the morphology of the nanostructured porous thin film. The photoconversion efficiency was further optimized as a function of film thickness. A maximum photoconversion efficiency of 0.924% from electrospun WO 3 nanofibers that EPD deposited on a substrate was achieved at a film thickness of 18 μm.

  9. Large optical second-order nonlinearity of poled WO3-TeO2 glass.

    Science.gov (United States)

    Tanaka, K; Narazaki, A; Hirao, K

    2000-02-15

    Second-harmonic generation, one of the second-order nonlinear optical properties of thermally and electrically poled WO>(3)-TeO>(2) glasses, has been examined. We poled glass samples with two thicknesses (0.60 and 0.86 mm) at various temperatures to explore the effects of external electric field strength and poling temperature on second-order nonlinearity. The dependence of second-harmonic intensity on the poling temperature is maximum at a specific poling temperature. A second-order nonlinear susceptibility of 2.1 pm/V was attained for the 0.60-mm-thick glass poled at 250 degrees C. This value is fairly large compared with those for poled silica and tellurite glasses reported thus far. We speculate that the large third-order nonlinear susceptibility of WO>(3)- TeO>(2) glasses gives rise to the large second-order nonlinearity by means of a X((2)) = 3X((3)) E(dc) process.

  10. Recent developments in crystal calorimeters (featuring the CMS PbWO4 electromagnetic calorimeter)

    International Nuclear Information System (INIS)

    Gascon-Shotkin, S.

    2003-01-01

    In the mass range of 110-150 GeV the favored process for Higgs boson detection via p-p collisions is via its decay into two photons, which demands a very high-resolution electromagnetic calorimeter. This physics goal plus the Large Hadron Calorimeter (LHC)-imposed design constraints of 25ns bunch spacing and a hostile radiation environment have led the Compact Muon Solenoid (CMS) collaboration to the choice of lead tungstate (PbWO 4 ) crystals. These factors plus the presence of a 4T magnetic field and the relatively low room-temperature scintillation photon yield of PbWO 4 make photo detection a real challenge, which CMS has met via the choice of devices providing gain amplification: Avalanche photodiodes (APD) in the central barrel region and vacuum phototriodes (VPT) in the forward and backward endcap regions. In the past year the CMS electromagnetic calorimeter has entered the construction phase. We review progress in the areas of crystals, barrel and endcap photo detection devices, plans for detector calibration as well as the status of assembly and quality control. We also invoke relevant developments in other crystal calorimeters currently in operation or under development. Crystal calorimeters remain the medium of choice for precision energy and position measurements in high energy physics

  11. Superior acidic catalytic activity and stability of Fe-doped HTaWO6 nanotubes

    KAUST Repository

    Liu, He; Zhang, Haitao; Fei, Linfeng; Ma, Hongbin; Zhao, Guoying; Mak, CheeLeung; Zhang, Xixiang; Zhang, Suojiang

    2017-01-01

    Fe-doped HTaWO6 (H1-3xFexTaWO6, x = 0.23) nanotubes as highly active solid acid catalysts were prepared via an exfoliation-scrolling-exchange process. The specific surface area and pore volume of undoped nanotubes (20.8 m2 g-1, 0.057 cm3 g-1) were remarkably enhanced through Fe3+ ion-exchange (>100 m2 g-1, 0.547 cm3 g-1). Doping Fe ions into the nanotubes endowed them with improved thermal stability due to the stronger interaction between the intercalated Fe3+ ions and the host layers. This interaction also facilitated the preservation of effective Brønsted acid sites and the generation of new acid sites. The integration of these functional roles resulted in Fe-doped nanotubes with high acidic catalytic activities in the Friedel-Crafts alkylation of anisole and the esterification of acetic acid. Facile accessibility to active sites, generation of effective Brønsted acid sites, high stability of the tubular structure and strong acid sites were found to synergistically contribute to the excellent acidic catalytic efficiency. Additionally, the activity of cycled nanocatalysts can be easily recovered through annealing treatment.

  12. Models of WO x films growth during pulsed laser deposition at elevated pressures of reactive gas

    Science.gov (United States)

    Gnedovets, A. G.; Fominski, V. Y.; Nevolin, V. N.; Romanov, R. I.; Fominski, D. V.; Soloviev, A. A.

    2017-12-01

    The films of tungsten oxides were prepared by pulsed laser ablation of W target in a reactive gas atmosphere (air of laboratory humidity). Optical analysis and ion signal measurements for the laser plume allowed to recognise a threshold gas pressure that suppresses the deposition of non-scattered atomic flux from the plume. When the pressure exceeds about 40 Pa, the films grow due to the deposition of species that could be formed in collisions of W atoms with reactive molecules (e.g., O2). Kinetic Monte Carlo method was used for modelling film growth. Comparison of the model structures with the experimentally prepared films has shown that the growth mechanism of ballistic deposition at a pressure of 40 Pa could be changed on the diffusion limited aggregation at a pressure of ~100 Pa. Thus, a cauliflower structure of the film transformed to a web-like structure. For good correlation of experimental and model structures of WO x , a dimension of structural elements in the model should coincide with W-O cluster size.

  13. Thermal and polarized spectroscopic characteristics of Nd3+:LiLa(WO4)2 crystal

    International Nuclear Information System (INIS)

    Huang Xinyang; Fang Qin; Yu Quanmiao; Lue Xingdong; Zhang Lizhen; Lin Zhoubin; Wang Guofu

    2009-01-01

    The thermal and polarized spectroscopic characteristics of Nd 3+ :LiLa(WO 4 ) 2 crystals have been investigated. The hardness of Nd 3+ :LiLa(WO 4 ) 2 crystal is 389.7 VDH. The specific heat at 330 K is 0.47 J g -1 K -1 . The thermal expansion coefficients for c- and a-axes are 7.70 x 10 -6 and 14.63 x 10 -5 deg. C -1 , respectively. The spectral parameters have been determined by Judd-Ofelt theory and Fuechtbauer-Ladenburg formula. The intensity parameters Ω t obtained are Ω 2 = 12.914 x 10 -20 cm 2 , Ω 4 = 3.79 x 10 -20 cm 2 , Ω 6 = 3.72 x 10 -20 cm 2 . The radiative and fluorescence lifetimes are 145 and 165 μs, respectively. The quantum efficiency is 91.9%. The absorption band at 805 nm has an FWHM of around 20 nm for both π- and σ-polarizations. The absorption cross-sections at 805 nm are 2.91 and 2.83 x 10 -20 cm 2 for π- and σ-polarizations, respectively. The stimulated emission cross-sections are 8.899 and 7.787 x 10 -20 cm 2 for π- and σ-polarizations, respectively

  14. A P25/(NH4)xWO3 hybrid photocatalyst with broad spectrum photocatalytic properties under UV, visible, and near-infrared irradiation.

    Science.gov (United States)

    Yang, Linfen; Liu, Bin; Liu, Tongyao; Ma, Xinlong; Li, Hao; Yin, Shu; Sato, Tsugio; Wang, Yuhua

    2017-04-03

    In this study, a series of hybrid nanostructured photocatalysts P25/(NH 4 ) x WO 3 nanocomposites with the average crystallite size of P25 and (NH 4 ) x WO 3 of the sample was calculated to be about 30 nm and 130 nm, were successfully synthesized via a simple one-step hydrothermal method. The as-obtained samples was characterized by transmission electron microscopy (TEM), which implies that the P25/(NH 4 ) x WO 3 nanocomposites are fabricated with favourable nanosizd interfacial. The XPS results confirmed that the obtained sample consists of mixed chemical valences of W 5+ and W 6+ , the low-valance W 5+ sites could be the origin of NIR absorption. As revealed by optical absorption results, P25/(NH 4 ) x WO 3 nanocomposites possess high optical absorption in the whole solar spectrum of 200-2500 nm. Benefiting from this unique photo-absorption property and the synergistic effect of P25 and (NH 4 ) x WO 3 , broad spectrum response photocatalytic activities covering UV, visible and near infrared regions on degradation of Rhodamine B have been realized by P25/(NH 4 ) x WO 3 nanocomposites. Meanwhile, the stability of photocatalysts was examined by the XRD and XPS of the photocatalysts after the reaction. The results show that P25/(NH 4 ) x WO 3 photocatalysts has a brilliant application prospect in the energy utilization to solve deteriorating environmental issues.

  15. Study of photocatalytic activities of Bi{sub 2}WO{sub 6} nanoparticles synthesized by fast microwave-assisted method

    Energy Technology Data Exchange (ETDEWEB)

    Phu, Nguyen Dang [Faculty of Physics, Hanoi National University of Education, 136 Xuanthuy, Cau Giay, Hanoi (Viet Nam); Hoang, Luc Huy, E-mail: hoanglhsp@hnue.edu.vn [Faculty of Physics, Hanoi National University of Education, 136 Xuanthuy, Cau Giay, Hanoi (Viet Nam); Chen, Xiang-Bai, E-mail: xchen@wit.edu.cn [School of Science and Laboratory of Optical Information Technology, Wuhan Institute of Technology, Wuhan 430205 (China); Kong, Meng-Hong [School of Science and Laboratory of Optical Information Technology, Wuhan Institute of Technology, Wuhan 430205 (China); Wen, Hua-Chiang; Chou, Wu Ching [Department of Electrophysics, National Chiao Tung University, Hsin-Chu 30010, Taiwan (China)

    2015-10-25

    We present a study of photocatalytic activities of Bi{sub 2}WO{sub 6} nanoparticles synthesized by fast microwave-assisted method. The photocatalytic activities of the nanoparticles were evaluated by the decolorization of methylene-blue under visible-light-irradiation. Our results show that the surface area of Bi{sub 2}WO{sub 6} nanoparticles plays a major role for improving photocatalytic activity, while visible-light absorption has only a weak effect on photocatalytic activity. This suggests efficient transportation of photo-generated electrons and holes to the oxidation active sites on the surface of nanoparticles, indicating Bi{sub 2}WO{sub 6} nanoparticles synthesized by fast microwave-assisted method are promising for achieving high photocatalytic activity under visible-light-irradiation. - Highlights: • The Bi{sub 2}WO{sub 6} nanoparticles were synthesized via fast microwave-assisted method. • The obtained Bi{sub 2}WO{sub 6} nanoparticles exhibited visible-light absorbance. • The surface area of Bi{sub 2}WO{sub 6} nanoparticles plays major role for improving photocatalytic activity. • The Bi{sub 2}WO{sub 6} nanoparticles are promising for achieving high photocatalytic activity under visible-light-irradiation.

  16. Relevance of Wnt10b and activation of β-catenin/GCMa/syncytin-1 pathway in BeWo cell fusion.

    Science.gov (United States)

    Malhotra, Sudha Saryu; Banerjee, Priyanka; Chaudhary, Piyush; Pal, Rahul; Gupta, Satish Kumar

    2017-10-01

    To study the involvement of specific Wnt(s) ligand during trophoblastic BeWo cell differentiation. BeWo cells on treatment with forskolin/human chorionic gonadotropin (hCG) were studied for cell fusion by desmoplakin I+II staining and/or hCG secretion by ELISA. Levels of Wnt10b/β-catenin/glial cell missing a (GCMa)/syncytin-1 were studied by qPCR/Western blotting in forskolin-/hCG-treated control siRNA and Wnt10b silenced BeWo cells. BeWo cells on treatment with hCG (5 IU/mL) led to a 94-fold increase in Wnt10b transcript. Wnt10b silencing showed significant decrease in forskolin-/hCG-mediated BeWo cell fusion and/or hCG secretion. It led to down-regulation of β-catenin (nuclear and cytoplasmic), GCMa and syncytin-1 expression. Treatment of BeWo cells with H89, protein kinase A (PKA) signaling inhibitor, significantly reduced forskolin-/hCG-induced Wnt10b, β-catenin, and syncytin-1 expression, which also resulted in reduced cell fusion. Wnt10b is involved in forskolin/hCG-mediated BeWo cell fusion via β-catenin/GCMa/syncytin pathway, which may also involve activation of PKA. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. `Joint Research and Development of Industrial Technology,` an international research collaboration for fiscal 1997. Research and development for practical application of low-temperature sinterable, highly heat-radiating materials for ceramics; 1997 nendo kokusai kenkyu kyoryoku jigyo `sangyo kiban gijutsu kyodo kenkyu kaihatsu`. Teion shoketsu kohonetsusei ceramics kiban zairyo no jitsuyoka gijutsu no kenkyu kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    A highly heat-conducting AlN ceramic substrate is developed for the cooling of semiconductor integrated circuit devices and power controlling semiconductor devices. In the development of a low-temperature sinterable ceramic texture, a sintering assistant is selected. In this process various assistants are tested for the effect of their presence on the occurrence of AlN oxidation and on the magnitude of standard energy for aluminate compound formation. The volatility at high temperatures of the components of the assistants are also examined. The sintering assistant developed for this project (mixture of Y2O3, CaO, LaB6, and WO3) is used in the sintering of an AlN material powder developed by The Dow Chemical Co., and then it is demonstrated that highly heat-conducting AlN substrates are mass-produced by continuous sintering at 1600degC in a nitrogen atmosphere, the product having a relative density of 100%, average heat conductivity of 154W/mK, bend resisting strength of 440MPa, and a fracture toughness value of 3.8MPam{sup 1/2}. 6 refs., 92 figs., 10 tabs.

  18. Reduced graphene oxide wrapped Bi{sub 2}WO{sub 6} hybrid with ultrafast charge separation and improved photoelectrocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huan [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, PR China (China); Liang, Yinghua, E-mail: liangyh@ncst.edu.cn [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, PR China (China); College of Chemical Engineering, North China University of Science and Technology, Tangshan 063009, PR China (China); Liu, Li; Hu, Jinshan [College of Chemical Engineering, North China University of Science and Technology, Tangshan 063009, PR China (China); Cui, Wenquan, E-mail: wkcui@163.com [College of Chemical Engineering, North China University of Science and Technology, Tangshan 063009, PR China (China)

    2017-01-15

    Highlights: • The rGO wrapped Bi{sub 2}WO{sub 6} photoelectrode was successfully synthesized. • The Bi{sub 2}WO{sub 6}@rGOhighlyincreasedthechargeseparationefficiency. • The photoelectrode exhibited enhanced photoelectrocatalytic degradation for RhB. - Abstract: A reduced graphene oxide (rGO) wrapped Bi{sub 2}WO{sub 6} (Bi{sub 2}WO{sub 6}@rGO) hybrid as photoelectrode for enhanced photoelectrocatalytic (PEC) degradation of organic pollutants is reported, which exhibited excellent charge separation and photoconversion efficiency. The core@shell structured Bi{sub 2}WO{sub 6}@rGO photoelectrode yielded a pronounced 1.56-fold and 23.8-fold photocurrent density at 1.0 V vs. saturated calomel electrode (SCE), than that of loading structured Bi{sub 2}WO{sub 6}-rGO and pure Bi{sub 2}WO{sub 6}. The Bi{sub 2}WO{sub 6}@rGO hybrid exhibited enhanced photoelectrocatalytic efficiency for degradation of Rhodamine B (RhB), which was 43.0% and 65.6% higher than that of photocatalytic (PC) and electrocatalytic (EC) processes, respectively. The enhancement in PEC degradation of RhB benefited from: (1) a strong interaction and a wide range of conjugation were formed in the core@shell system; (2) a 0.26 V of flat band potential was negatively shifted in case of Bi{sub 2}WO{sub 6}@rGO composite; (3) the photogenerated electrons and holes could be spatially separated by external electric potentials.

  19. Ease synthesis of mesoporous WO3-TiO2 nanocomposites with enhanced photocatalytic performance for photodegradation of herbicide imazapyr under visible light and UV illumination.

    Science.gov (United States)

    Ismail, Adel A; Abdelfattah, Ibrahim; Helal, Ahmed; Al-Sayari, S A; Robben, L; Bahnemann, D W

    2016-04-15

    Herein, we report the ease synthesis of mesoporous WO3-TiO2 nanocomposites at different WO3 contents (0-5wt%) together with their photocatalytic performance for the degradation of the imazapyr herbicide under visible light and UV illumination. XRD and Raman spectra indicated that the highly crystalline anatase TiO2 phase and monoclinic and triclinic of WO3 were formed. The mesoporous TiO2 exhibits large pore volumes of 0.267cm(3)g-1 and high surface areas of 180m(2)g(-1) but they become reduced to 0.221cm(3)g(-1) and 113m(2)g(-1), respectively upon WO3 incorporation, with tunable mesopore diameter in the range of 5-6.5nm. TEM images show WO3-TiO2 nanocomposites are quite uniform with 10-15nm of TiO2 and 5-10nm of WO3 sizes. Under UV illumination, the overall photocatalytic efficiency of the 3% WO3-TiO2 nanocomposite is 3.5 and 6.6 times higher than that of mesoporous TiO2 and commercial UV-100 photocatalyst, respectively. The 3% WO3-TiO2 nanocomposite is considered to be the optimum photocatalyst which is able to degrade completely (100% conversion) of imazapyr herbicide along 120min with high photonic efficiency ∼8%. While under visible light illumination, the 0.5% WO3-TiO2 nanocomposite is the optimum photocatalyst which achieves 46% photocatalytic efficiency. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. The effects of solvent on photocatalytic properties of Bi2WO6/TiO2 heterojunction under visible light irradiation

    Science.gov (United States)

    Guo, Qiyao; Huang, Yunfang; Xu, Hui; Luo, Dan; Huang, Feiyue; Gu, Lin; Wei, Yuelin; Zhao, Huang; Fan, Leqing; Wu, Jihuai

    2018-04-01

    Bi2WO6/TiO2 heterojunction photocatalysts with two different microstructures were controllably fabricated via a facile two-step synthetic route. XRD, XPS, SEM, TEM, BET-surface, DRS, PL spectra, photoelectrochemical measurement (Mott-Schottky), and zeta-potential analyzer were employed to clarify structural and morphological characteristics of the obtained products. The results showed that Bi2WO6 nanoparticles/nanosheets grew on the primary TiO2 nanorods. The TiO2 nanorods used as a synthetic template inhibit the growth of Bi2WO6 crystals along the c-axis, resulting in Bi2WO6/TiO2 heterostructure with one-dimensional (1D) morphology. The photocatalytic properties of Bi2WO6/TiO2 heterojunction photocatalysts were strongly dependent on their shapes and structures. Compared with bare Bi2WO6 and TiO2, Bi2WO6/TiO2 composite have stronger adsorption ability and better visible light photocatalytic activities towards organic dyes. The Bi2WO6/TiO2 composite prepared in EG solvent with optimal Bi:Ti ratio of 2:12 (S-TB2) showed the highest photocatalytic activity, which could totally decompose Rhodamine B within 10 min upon irradiation with visible light (λ > 422 nm), and retained the high photocatalytic performance after five recycles, confirming its stability and practical usability. The results of PL indicated that Bi2WO6 and TiO2 could combine well to form a heterojunction structure which facilitated electron-hole separation, and lead to the increasing photocatalytic activity.

  1. Study on photocurrent of bilayers photoanodes using different combination of WO{sub 3} and Fe{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Memar, Amir; Daud, Wan Ramli Wan; Eftekhari, Ehsan; Minggu, Lorna Jeffery [Institute of Fuel Cell, University Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Hosseini, Soraya [Department Chemical and Environmental Engineering, University Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)

    2010-08-15

    Bilayer photoanodes were prepared onto glass substrates (FTO) in order to improve generated photocurrents using UV-vis light by water splitting process. A comparative study of photocatalytic was performed over the films surface using Fe{sub 2}O{sub 3,} WO{sub 3} and mixture of bicomponents (Fe{sub 2}O{sub 3}:WO{sub 3}). Different types of films were prepared using Fe{sub 2}O{sub 3,} WO{sub 3} and bicomponents (mixture) on FTO substrates. The films were grown by sol gel method with the PEG-300 as the structure-directing agent. The photo-generated of the samples were determined by measuring the currents and voltages under illumination of UV-vis light. The morphology, structure and related composition distribution of the films have been characterized by SEM, XRD and EDX respectively. Photocurrent measurements indicated surface roughness as the effective parameter in this study. The deposited surfaces by bicomponents or mixture are flat without any feature on the surface while the deposited surfaces by WO{sub 3} appears rough surface as small round (egg-shaped particles) and cauliflower-like. The surface deposited by Fe{sub 2}O{sub 3} show rough no as well as WO{sub 3} surface. The deposited surfaces by WO{sub 3} reveal the higher value of photocurrent measurement due to surface roughness. Indeed, the roughness can be effective in increasing contact surface area between film and electrolyte and diffuse reflection (light scattering effect). The solution (Fe{sub 2}O{sub 3}:WO{sub 3}) shows the low photocurrent value in compare to WO{sub 3} and Fe{sub 2}O{sub 3} hat it may be due to decomposition the compound at 450 {+-} 1 C to iron-tungstate Fe{sub 2}(WO{sub 4}){sub 3}. (author)

  2. Ag/AgCl Loaded Bi2WO6 Composite: A Plasmonic Z-Scheme Visible Light-Responsive Photocatalyst

    Directory of Open Access Journals (Sweden)

    Xiangchao Meng

    2016-01-01

    Full Text Available Hierarchical flower-like Bi2WO6 was successfully synthesized by facile hydrothermal method at low pH. And Ag/AgCl was loaded by photoreduction on its surface. As-prepared photocatalysts were characterized by various techniques. Bi2WO6 was successfully synthesized at a size of 2-3 μm. Depositing Ag/AgCl did not destroy the crystal structure, and both Ag+ and metallic Ag0 were found. The band gap of the composite was 2.57 eV, which indicates that visible light could be the activating irradiation. In the photocatalytic activity test, the composite with 10 wt% Ag/AgCl boasted the highest removal efficiency (almost 100% in 45 min. The significant enhancement can be attributed to the surface plasmon resonance (SPR effect and the establishment of heterostructures between Ag/AgCl and Bi2WO6. A possible mechanism of photocatalytic oxidation in the presence of Ag/AgCl-Bi2WO6 was proposed. This work sheds light on the potential applications of plasmonic metals in photocatalysis to enhance their activities.

  3. Transdermal delivery of hydrophobic and hydrophilic local anesthetics from o/w and w/o Brij 97-based microemulsions

    DEFF Research Database (Denmark)

    Junyaprasert, Varaporn Buraphacheep; Boonme, Prapaporn; Songkro, Sarunyoo

    2007-01-01

    To characterize the physicochemical properties of drug-loaded oil-in-water (o/w) and water-in-oil (w/o) Brij 97-based microemulsions in comparison to their blank counterparts and to investigate the influence of microemulsion type on in vitro skin permeation of model hydrophobic drugs...

  4. UV-Vis optoelectronic properties of α-SnWO4: A comparative experimental and density functional theory based study

    KAUST Repository

    Ziani, Ahmed; Harb, Moussab; Noureldine, Dalal; Takanabe, Kazuhiro

    2015-01-01

    and density functional perturbation theory using the HSE06 functional. The α-SnWO4 material shows an indirect bandgap of 1.52 eV with high absorption coefficient in the visible-light range (>2 × 105 cm−1). The results show relatively high dielectric constant

  5. Degradation of dimethylformamide on the surface of the nanosized WO{sub 3} films studied by infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gavrilyuk, A.I., E-mail: gavrilyuk@mail.ioffe.ru

    2016-07-30

    Highlights: • Dimethylformamide was adsorbed on the surface of the nanosized WO{sub 3} films. • The mechanism of the adsorption was investigated by IR spectroscopy. • The transformations of the adsorbed molecules either in dark or under the action of light was discussed. - Abstract: Here I report on the degradation of dimethylformamide on the surface of the nanosized WO{sub 3} films under the action of light. Dimethylformamide, a substance that has a series of interesting properties, was adsorbed on the surface of the WO{sub 3} films and its adsorption mechanism and transformations under the action of light have been investigated with the help of the IR spectroscopy. The spirit of the research is that both DMF modifications have been used i.e., conventional and that with the substitution of hydrogen atoms by deuterium. Formation of two weak bonds (donor-acceptor bond and hydrogen bond) provides a great catalytic effect for photo-initiated proton-coupled electron transfer from the adsorbed molecules to the WO{sub 3} film surface. The mechanism of the detachment of hydrogen atoms and subsequent transformation of the adsorbed molecules has been investigated and discussed.

  6. Sulfur Nanoparticles Synthesis and Characterization from H2S Gas, Using Novel Biodegradable Iron Chelates in W/O Microemulsion

    Directory of Open Access Journals (Sweden)

    Harle Arti

    2008-01-01

    Full Text Available AbstractSulfur nanoparticles were synthesized from hazardous H2S gas using novel biodegradable iron chelates in w/o microemulsion system. Fe3+–malic acid chelate (0.05 M aqueous solution was studied in w/o microemulsion containing cyclohexane, Triton X-100 andn-hexanol as oil phase, surfactant, co-surfactant, respectively, for catalytic oxidation of H2S gas at ambient conditions of temperature, pressure, and neutral pH. The structural features of sulfur nanoparticles have been characterized by X-ray diffraction (XRD, transmission electron microscope (TEM, energy dispersive spectroscopy (EDS, diffused reflectance infra-red Fourier transform technique, and BET surface area measurements. XRD analysis indicates the presence of α-sulfur. TEM analysis shows that the morphology of sulfur nanoparticles synthesized in w/o microemulsion system is nearly uniform in size (average particle size 10 nm and narrow particle size distribution (in range of 5–15 nm as compared to that in aqueous surfactant systems. The EDS analysis indicated high purity of sulfur (>99%. Moreover, sulfur nanoparticles synthesized in w/o microemulsion system exhibit higher antimicrobial activity (against bacteria, yeast, and fungi than that of colloidal sulfur.

  7. Efficient room temperature oxidation of cyclohexane over highly active hetero-mixed WO3/V2O5 oxide catalyst

    CSIR Research Space (South Africa)

    Makgwane, PR

    2014-09-01

    Full Text Available catalytic activity to initiate the free-radical oxyfunctionalization of cyclohexane to afford up to 90% conversions within 6 h. The KA selectivity was found to depend on reaction time and the amount of catalyst. The WO(sub3)/V(sub2)O(sub5) catalyst...

  8. Microwave assisted hydrothermal synthesis of Ag/AgCl/WO3 photocatalyst and its photocatalytic activity under simulated solar light

    International Nuclear Information System (INIS)

    Adhikari, Rajesh; Gyawali, Gobinda; Sekino, Tohru; Wohn Lee, Soo

    2013-01-01

    Simulated solar light responsive Ag/AgCl/WO 3 composite photocatalyst was synthesized by microwave assisted hydrothermal process. The synthesized powders were characterized by X-Ray Diffraction (XRD) spectroscopy, X-Ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Diffuse Reflectance Spectroscopy (UV–Vis DRS), and BET surface area analyzer to investigate the crystal structure, morphology, chemical composition, optical properties and surface area of the composite photocatalyst. This photocatalyst exhibited higher photocatalytic activity for the degradation of rhodamine B under simulated solar light irradiation. Dye degradation efficiency of composite photocatalyst was found to be increased significantly as compared to that of the commercial WO 3 nanopowder. Increase in photocatalytic activity of the photocatalyst was explained on the basis of surface plasmon resonance (SPR) effect caused by the silver nanoparticles present in the composite photocatalyst. Highlights: ► Successful synthesis of Ag/AgCl/WO 3 nanocomposite. ► Photocatalytic experiment was performed under simulated solar light. ► Nanocomposite photocatalyst was very active as compared to WO 3 commercial powder. ► SPR effect due to Ag nanoparticles enhanced the photocatalytic activity.

  9. Intrinsic trapping and recombination centers in CdWO.sub.4./sub. investigated using thermally stimulated luminescence

    Czech Academy of Sciences Publication Activity Database

    Vedda, A.; Moretti, F.; Fasoli, M.; Nikl, Martin; Laguta, Valentyn

    2009-01-01

    Roč. 80, č. 4 (2009), 045104/1-045104/7 ISSN 1098-0121 R&D Projects: GA AV ČR IAA100100810 Institutional research plan: CEZ:AV0Z10100521 Keywords : CdWO 4 * thermoluminescence * traps * rekombination centers Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

  10. 3D WO3 /BiVO4 /Cobalt Phosphate Composites Inverse Opal Photoanode for Efficient Photoelectrochemical Water Splitting.

    Science.gov (United States)

    Zhang, Haifeng; Zhou, Weiwei; Yang, Yaping; Cheng, Chuanwei

    2017-04-01

    A novel 3D WO 3 /BiVO 4 /cobalt phosphate composite inverse opal is designed for photoeletrochemical (PEC) water splitting, yielding a significantly improved PEC performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. A novel orange emissive phosphor SrWO4:Sm3+ for white light-emitting diodes

    International Nuclear Information System (INIS)

    Ju Zhenghua; Wei Ruiping; Ma Jingxin; Pang Chaoran; Liu Weisheng

    2010-01-01

    Research highlights: → A novel orange emissive phosphor SrWO 4 :Sm 3+ was firstly reported. → The optics properties of Sm 3+ -doped SrWO 4 phosphor were successfully discussed. → The temperature-dependent luminescence indicates the phosphor exhibits a small thermal-quenching property. → The phosphor is a potential candidate as orange-emitting component for white LED. - Abstract: A novel orange emissive phosphor, Sm 3+ -doped SrWO 4 , was synthesized by high temperature solid-state reaction in air atmosphere. The excitation spectra show that the phosphors can be efficiently excited by ultraviolet and near-ultraviolet light, the optimized concentration is 4 mol%. Three emission peaks locate at 562, 596 and 642 nm, corresponding to CIE chromaticity coordinates of (x = 0.54, y = 0.46), which indicates the orange light emitting. The decay curves are well fitted with triple-exponential decay models. The quantum yield of the Sr 0.96 Sm 0.04 WO 4 phosphor is about 70.65% under excitation of 377 nm. Furthermore, the temperature-dependent luminescence indicates the phosphor exhibits a small thermal-quenching property. So the phosphor is able to be applied to UV-LED chip-based white light-emitting diodes.

  12. Iron metabolism in BeWo chorion carcinoma cells. Transferrin-mediated uptake and release of iron

    NARCIS (Netherlands)

    van der Ende, A.; du Maine, A.; Simmons, C. F.; Schwartz, A. L.; Strous, G. J.

    1987-01-01

    Growing human choriocarcinoma BeWo b24 cells contain 1.5 X 10(6) functional cell surface transferrin binding sites and 2.0 X 10(6) intracellular binding sites. These cells rapidly accumulate iron at a rate of 360,000 iron atoms/min/cell. During iron uptake the transferrin and its receptor recycle at

  13. Abnormal network flow detection based on application execution patterns from Web of Things (WoT) platforms.

    Science.gov (United States)

    Yoon, Young; Jung, Hyunwoo; Lee, Hana

    2018-01-01

    In this paper, we present a research work on a novel methodology of identifying abnormal behaviors at the underlying network monitor layer during runtime based on the execution patterns of Web of Things (WoT) applications. An execution pattern of a WoT application is a sequence of profiled time delays between the invocations of involved Web services, and it can be obtained from WoT platforms. We convert the execution pattern to a time sequence of network flows that are generated when the WoT applications are executed. We consider such time sequences as a whitelist. This whitelist reflects the valid application execution patterns. At the network monitor layer, our applied RETE algorithm examines whether any given runtime sequence of network flow instances does not conform to the whitelist. Through this approach, it is possible to interpret a sequence of network flows with regard to application logic. Given such contextual information, we believe that the administrators can detect and reason about any abnormal behaviors more effectively. Our empirical evaluation shows that our RETE-based algorithm outperforms the baseline algorithm in terms of memory usage.

  14. Electronic structure and magnetic properties of FeWO{sub 4} nanocrystals synthesized by the microwave-hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, M.A.P. [INCTMN-DQ-Universidade Federal de Sao Carlos, Sao Carlos, P.O. Box 676, 13565-905, SP (Brazil); Cavalcante, L.S., E-mail: laeciosc@bol.com.br [INCTMN-Universidade Estadual, Paulista, P.O. Box 355, 14801-907, Araraquara, SP (Brazil); Morilla-Santos, C.; Filho, P.N. Lisboa [MAv-Universidade Estadual, Paulista, P.O. Box 473, 17033-360, Bauru, SP (Brazil); Beltran, A.; Andres, J.; Gracia, L. [Department de Quimica Fisica i Analitica, Universitat Jaume I, E-12071 Castello (Spain); Longo, E. [INCTMN-DQ-Universidade Federal de Sao Carlos, Sao Carlos, P.O. Box 676, 13565-905, SP (Brazil); INCTMN-Universidade Estadual, Paulista, P.O. Box 355, 14801-907, Araraquara, SP (Brazil)

    2012-11-15

    This communication reports that FeWO{sub 4} nanocrystals were successfully synthesized by the microwave-hydrothermal method at 443 K for 1 h. The structure and shape of these nanocrystals were characterized by X-ray diffraction, Rietveld refinement, and transmission electron microscopy. The experimental results and first principles calculations were combined to explain the electronic structure and magnetic properties. Experimental data were obtained by magnetization measurements for different applied magnetic fields. Theoretical calculations revealed that magnetic properties of FeWO{sub 4} nanocrystals can be assigned to two magnetic orderings with parallel or antiparallel spins in adjacent chains. These factors are crucial to understanding of competition between ferro- and antiferromagnetic behavior. Highlights: Black-Right-Pointing-Pointer Monophasic FeWO{sub 4} nanocrystals were synthesized by the microwave-hydrothermal method. Black-Right-Pointing-Pointer Rietveld refinement and clusters model for monoclinic structure Black-Right-Pointing-Pointer Magnetic properties of FeWO{sub 4} nanocrystals at different temperatures.

  15. Alginate submicron beads prepared through w/o emulsification and gelation with CaCl2 nanoparticles

    NARCIS (Netherlands)

    Paques, J.P.; Linden, van der E.; Rijn, van C.J.M.; Sagis, L.M.C.

    2013-01-01

    A simple method for preparing gelled alginate beads with a diameter smaller than 5 µm is described. A 1% alginate solution and a medium chain triglyceride (MCT) oil are used to prepare a water-in-oil (w/o) emulsion, stabilized by polyglycerol polyricinoleate. CaCl2 nanoparticles with dimensions in

  16. In situ growth of Ag nanoparticles on α-Ag2WO4 under electron irradiation: probing the physical principles

    Science.gov (United States)

    San-Miguel, Miguel A.; da Silva, Edison Z.; Zannetti, Sonia M.; Cilense, Mario; Fabbro, Maria T.; Gracia, Lourdes; Andrés, Juan; Longo, Elson

    2016-06-01

    Exploiting the plasmonic behavior of Ag nanoparticles grown on α-Ag2WO4 is a widely employed strategy to produce efficient photocatalysts, ozone sensors, and bactericides. However, a description of the atomic and electronic structure of the semiconductor sites irradiated by electrons is still not available. Such a description is of great importance to understand the mechanisms underlying these physical processes and to improve the design of silver nanoparticles to enhance their activities. Motivated by this, we studied the growth of silver nanoparticles to investigate this novel class of phenomena using both transmission electron microscopy and field emission scanning electron microscopy. A theoretical framework based on density functional theory calculations (DFT), together with experimental analysis and measurements, were developed to examine the changes in the local geometrical and electronic structure of the materials. The physical principles for the formation of Ag nanoparticles on α-Ag2WO4 by electron beam irradiation are described. Quantum mechanical calculations based on DFT show that the (001) of α-Ag2WO4 displays Ag atoms with different coordination numbers. Some of them are able to diffuse out of the surface with a very low energy barrier (less than 0.1 eV), thus, initiating the growth of metallic Ag nanostructures and leaving Ag vacancies in the bulk material. These processes increase the structural disorder of α-Ag2WO4 as well as its electrical resistance as observed in the experimental measurements.

  17. Physical characteristic and irritation index of Syzigium aromaticum essential oil in O/W and W/O creams

    Science.gov (United States)

    Safriani, R.; Sugihartini, N.; Yuliani, S.

    2017-11-01

    Essential oil of Syzigium aromaticum has been formulated in O/W and W/O creams as anti-inflammatory dosage form. The purpose of this study was to evaluate the physical characteristic and irritation index of S. aromaticum essential oil in O/W and W/O creams. The creams were made by fusion method. The creams then were evaluated the physical characteristic including pH, viscosity, spreadability and adhesivity. The irritation index was obtained by irritation skin test in male rabbit. The results showed that the W/O and O/W creams have the value of pH: 6.3 and 6.27; spreadability: 3,18 and 4.17 cm2; adhesivity: 5.59 and 0.07 minutes; viscosity: 4.43 and 2.88 Pa.S, respectively. The irritation test showed that the control enhancer caused mild irritation in both of W/O and O/W creams. These findings indicated that type of cream might influence the physical characteristic and irritation index of S. aromaticum essential oil cream.

  18. A mesoporous WO3−X/graphene composite as a high-performance Li-ion battery anode

    International Nuclear Information System (INIS)

    Liu, Fei; Kim, Jong Gu; Lee, Chul Wee; Im, Ji Sun

    2014-01-01

    Graphical abstract: The highly flexible and conductive graphene layer can enhance electron transfer, protect metal oxides against disintegration and aggregation and buffer the strain induced by volume expansion during cycles. The mesoporous surface layer provides an open network for Li+ diffusion. - Highlights: • Novel cocktail effects of 2D mesoporous WO 3−X /graphene for lithium ion battery. • New approach for lithium ion battery by easy and unique synthesis method. • Mechanism study with proper data for understanding a reaction on anode surface. - Abstract: A novel mesoporous WO 3−X /graphene composite was developed. This material allowed rapid electron and Li + ion diffusion when used as a Li-ion battery (LIB) anode material. Remarkably, the graphene support protected WO 3−X from changing volume during the electrochemical cycling process; this process generally induces capacity loss. The current work describes a high-performance anode material for LIB that has highly dense WO 3−X , as well as high capacity, rate capability and stability

  19. Low-temperature liquid phase epitaxy of rare-earth-ion doped KY(WO4)2 thin layers

    NARCIS (Netherlands)

    Romanyuk, Y.E.; Utke, I.; Ehrentraut, D.; Pollnau, Markus; Garcia-Revilla, S.; Valiente, R.; Kuleshov, N.V.

    2004-01-01

    Rare-earth-ion doped KY(WO4)2 (hereafter KYW) is a promising material for novel solid-state lasers. Low laser threshold, high efficiency, high output powers, and third-order nonlinear effects have stimulated research towards miniaturized thin-film waveguide lasers and amplifiers for future photonic

  20. Growth of Yb3+, Lu3+, Gd3+ co-doped KY(WO4)2 thin layers

    NARCIS (Netherlands)

    Aravazhi, S.; Geskus, D.; Pollnau, Markus; Worhoff, Kerstin; Agazzi, L.; Ismail, N.; Leijtens, X

    2008-01-01

    Rare-earth-ion-doped $KY(WO_4)_2 (KYW)$ is an important candidate for solid-state lasers. Its high refractive indices of the order of 2.0 make it attractive also for applications as integrated optical devices. Liquid phase epitaxy was employed for growing mono-crystalline KYW thin films co-doped

  1. Photocatalytic activity of bipolar pulsed magnetron sputter deposited TiO{sub 2}/TiWO{sub x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Weng, Ko-Wei; Hu, Chung-Hsuan; Hua, Li-Yu; Lee, Chin-Tan [Department of Electronic Engineering, National Quemoy University, 1 Daxue Road, Jinning Township, Kinmen 89250, Taiwan, ROC (China); Zhao, Yu-Xiang [Department of Computer Science and Information Engineering, National Quemoy University, Taiwan, ROC (China); Chang, Julian; Yang, Shu-Yi [Department of Applied English, National Quemoy University, Taiwan, ROC (China); Han, Sheng, E-mail: shenghan@nutc.edu.tw [Center for General Education, National Taichung University of Science and Technology, 129 San-min Road, Section 3, Taichung 40401, Taiwan, ROC (China)

    2016-08-15

    Highlights: • TiO{sub 2}/TiWO{sub x} films were fabricated by a bipolar pulsed magnetron sputtering apparatus. • Titanium oxide being sputtered tungsten enhanced the highly oriented of TiO{sub 2} (1 0 1) plane of the specimen assemblies. • The mechanism WO{sub 3}(h{sup +}, e{sup −})/TiO{sub 2}(h{sup +}, e{sup −}) → WO{sub 3}(e{sup −})/TiO{sub 2}(h{sup +}) shows the higher hydrophilicity and lower contact angle. - Abstract: Titanium oxide films were formed by sputtering and then TiWO{sub x} films were deposited by bipolar pulsed magnetron sputtering with pure titanium and tungsten metal targets. The sputtering of titanium oxide with tungsten enhanced the orientation of the TiO{sub 2} (1 0 1) plane of the specimen assemblies. The main varying parameter was the tungsten pulse power. Titanium oxide sputtered with tungsten using a pulsing power of 50 W exhibited a superior hydrophilic property, and a contact angle of 13.1°. This fabrication conditions maximized the photocatalytic decomposition of methylene blue solution. The mechanism by which the titanium oxide was sputtered with tungsten involves the photogeneration of holes and electron traps, inhibiting the hole–electron recombination, enhancing hydrophilicity and reducing the contact angle.

  2. Thermal oxidation of seeds for the hydrothermal growth of WO{sub 3} nanorods on ITO glass substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Chai Yan [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Department of Mechanical and Material Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Sungai Long, Bandar Sungai Long, Cheras, 43000 Kajang, Selangor (Malaysia); Abdul Razak, Khairunisak, E-mail: khairunisak@usm.my [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); NanoBiotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lockman, Zainovia, E-mail: zainovia@usm.my [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2015-11-30

    This work reports a simple seed formation method for the hydrothermal growth of tungsten oxide (WO{sub 3}) nanorods. A WO{sub 3} seed layer was prepared by thermal oxidation, where a W-sputtered substrate was heated and oxidized in a furnace. Oxidation temperatures and periods were varied at 400–550 °C and 5–60 min, respectively, to determine an appropriate seed layer for nanorod growth. Thermal oxidation at 500 °C for 15 min was found to produce a seed layer with sufficient crystallinity and good adhesion to the substrate. These properties prevented the seed from peeling off during the hydrothermal process, thereby allowing nanorod growth on the seed. The nanorod film showed better electrochromic behavior (higher current density of − 1.11 and + 0.65 mA cm{sup −2}) than compact film (lower current density of − 0.54 and + 0.28 mA cm{sup −2}). - Highlights: • A simple seed formation method (thermal oxidation) on sputtered W film is reported. • Crystalline seed with good adhesion to substrate is required for nanorod growth. • The appropriate temperature and period for seed formation were 500 °C and 15 min. • WO{sub 3} nanorods exhibited higher electrochromic current density than WO{sub 3} compact film.

  3. Bi3+ sensitized Y2WO6:Ln3+ (Ln=Dy, Eu, and Sm) phosphors for solar spectral conversion.

    Science.gov (United States)

    Huang, M N; Ma, Y Y; Xiao, F; Zhang, Q Y

    2014-01-01

    The phosphors of Y2WO6:Bi3+, Ln3+ (Ln=Dy, Eu and Sm) were synthesized by solid-state reaction in this study. The crystal structure, photoluminescence properties and energy transfer mechanism were investigated. By introducing Bi3+ ions, the excitation band of the phosphors was broadened to be 250-380 nm, which could be absorbed by the dye-sensitized solar cells (DSSCs). The overlap between excitation of W-O groups/Bi3+ and the emission of Ln3+ (Dy, Eu, and Sm) indicated that the probability of energy transfer from W-O groups and Bi3+ to Ln3+. The energy transfer efficiency from Bi3+ to Ln3+ (Ln=Dy, Eu and Sm) are calculated to be 16%, 20% and 58%. This work suggested that Y2WO6:Bi3+, Ln3+ (Ln=Dy, Eu and Sm) might be a promising ultraviolet-absorbing luminescent converter to enhance the photoelectrical conversion efficiency of dye-sensitized solar cells (DSSCs). Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Focused-ion-beam nano-structured rib channel waveguides in KY(WO4)2 for laser applications

    NARCIS (Netherlands)

    Gardillou, F.; Romanyuk, Y.E.; Pavius, M.; Borca, C.N.; Salathé, R.P.; Pollnau, Markus

    2006-01-01

    Bulk $KY(WO_4)_2$ (hereafter KYW) laser crystals doped with rare-earth ions are recognized to be among the most promising host materials for obtaining novel solid-state lasers. The rare-earth ions $RE^{3+}$ are easily incorporated in the KYW structure by replacing the $Y{3+}$ ions, resulting in a

  5. Modeling placental transport: correlation of in vitro BeWo cell permeability and ex vivo human placental perfusion

    DEFF Research Database (Denmark)

    Poulsen, Marie Sønnegaard; Rytting, Erik; Mose, Tina

    2009-01-01

    across the BeWo cells was observed in the rank order of caffeine>antipyrine>benzoic acid>glyphosate in terms of both the apparent permeability coefficient and the initial slope, defined as the linear rate of substance transferred to the fetal compartment as percent per time, a parameter used to compare...

  6. Improvement of optical properties and radiation hardness of NaBi(WO sub 4) sub 2 Cherenkov crystals

    CERN Document Server

    Zadneprovski, B I; Polyansky, E V; Devitsin, E G; Kozlov, V A; Potashov, S Yu; Terkulov, A R

    2002-01-01

    On the basis of the data on melt evaporation while growing NaBi(WO sub 4) sub 2 Cherenkov crystals, the formation of nonstoichiometry and most probable types of dot defects of the crystals have been considered. The influence of melt nonstoichiometry and doping with Sc on optical transmission and radiation hardness of the crystals has been experimentally investigated. The surplus of WO sub 3 has been established to increase optical transmission and radiation hardness and lack of Bi sub 2 O sub 3 in the melt to reduce radiation hardness. Sc doping is shifting the absorption edge to UV region by 30-35 nm and is increasing radiation hardness of the crystals about three-fold. Analytical estimations give the increase of the number of Cherenkov photons by a factor of 1.3, which leads to an improvement of the energy resolution of a calorimeter based on NaBi(WO sub 4) sub 2 :Sc crystals compared with undoped NaBi(WO sub 4) sub 2 of approximately 15%.

  7. Photocatalytic degradation of 2-propanol and phenol using Au loaded MnWO4 nanorod under visible light irradiation

    CSIR Research Space (South Africa)

    Chakraborty, AK

    2012-06-01

    Full Text Available ) under visible light ( = 420 nm) irradiation. The Au loading was optimized to 3.79 wt% for the highest efficiency. The enhanced photocatalytic activity originates from the absorption of visible light by MnWO4 as well as the introduction...

  8. Global coordination and standardisation in marine biodiversity through the World Register of Marine Species (WoRMS and related databases.

    Directory of Open Access Journals (Sweden)

    Mark J Costello

    Full Text Available The World Register of Marine Species is an over 90% complete open-access inventory of all marine species names. Here we illustrate the scale of the problems with species names, synonyms, and their classification, and describe how WoRMS publishes online quality assured information on marine species. Within WoRMS, over 100 global, 12 regional and 4 thematic species databases are integrated with a common taxonomy. Over 240 editors from 133 institutions and 31 countries manage the content. To avoid duplication of effort, content is exchanged with 10 external databases. At present WoRMS contains 460,000 taxonomic names (from Kingdom to subspecies, 368,000 species level combinations of which 215,000 are currently accepted marine species names, and 26,000 related but non-marine species. Associated information includes 150,000 literature sources, 20,000 images, and locations of 44,000 specimens. Usage has grown linearly since its launch in 2007, with about 600,000 unique visitors to the website in 2011, and at least 90 organisations from 12 countries using WoRMS for their data management. By providing easy access to expert-validated content, WoRMS improves quality control in the use of species names, with consequent benefits to taxonomy, ecology, conservation and marine biodiversity research and management. The service manages information on species names that would otherwise be overly costly for individuals, and thus minimises errors in the application of nomenclature standards. WoRMS' content is expanding to include host-parasite relationships, additional literature sources, locations of specimens, images, distribution range, ecological, and biological data. Species are being categorised as introduced (alien, invasive, of conservation importance, and on other attributes. These developments have a multiplier effect on its potential as a resource for biodiversity research and management. As a consequence of WoRMS, we are witnessing improved

  9. Global Coordination and Standardisation in Marine Biodiversity through the World Register of Marine Species (WoRMS) and Related Databases

    Science.gov (United States)

    Bouchet, Philippe; Boxshall, Geoff; Fauchald, Kristian; Gordon, Dennis; Hoeksema, Bert W.; Poore, Gary C. B.; van Soest, Rob W. M.; Stöhr, Sabine; Walter, T. Chad; Vanhoorne, Bart; Decock, Wim

    2013-01-01

    The World Register of Marine Species is an over 90% complete open-access inventory of all marine species names. Here we illustrate the scale of the problems with species names, synonyms, and their classification, and describe how WoRMS publishes online quality assured information on marine species. Within WoRMS, over 100 global, 12 regional and 4 thematic species databases are integrated with a common taxonomy. Over 240 editors from 133 institutions and 31 countries manage the content. To avoid duplication of effort, content is exchanged with 10 external databases. At present WoRMS contains 460,000 taxonomic names (from Kingdom to subspecies), 368,000 species level combinations of which 215,000 are currently accepted marine species names, and 26,000 related but non-marine species. Associated information includes 150,000 literature sources, 20,000 images, and locations of 44,000 specimens. Usage has grown linearly since its launch in 2007, with about 600,000 unique visitors to the website in 2011, and at least 90 organisations from 12 countries using WoRMS for their data management. By providing easy access to expert-validated content, WoRMS improves quality control in the use of species names, with consequent benefits to taxonomy, ecology, conservation and marine biodiversity research and management. The service manages information on species names that would otherwise be overly costly for individuals, and thus minimises errors in the application of nomenclature standards. WoRMS' content is expanding to include host-parasite relationships, additional literature sources, locations of specimens, images, distribution range, ecological, and biological data. Species are being categorised as introduced (alien, invasive), of conservation importance, and on other attributes. These developments have a multiplier effect on its potential as a resource for biodiversity research and management. As a consequence of WoRMS, we are witnessing improved communication within the

  10. Preparation of Porous F-WO3/TiO2 Films with Visible-Light Photocatalytic Activity by Microarc Oxidation

    OpenAIRE

    Yeh, Chung-Wei; Wu, Kee-Rong; Hung, Chung-Hsuang; Chang, Hao-Cheng; Hsu, Chuan-Jen

    2012-01-01

    Porous F-WO3/TiO2 (mTiO2) films are prepared on titanium sheet substrates using microarc oxidation (MAO) technique. The X-ray diffraction patterns show that visible-light (Vis) enabling mTiO2 films with a very high content of anatase TiO2 and high loading of WO3 are successfully synthesized at a low applied voltage of 300 V using electrolyte contenting NaF and Na2WO4 without subsequent heat treatment. The cross-sectional transmission electron microscopy micrograph reveals that the mTiO2 films...

  11. Preparation of WO{sub 3}/g-C{sub 3}N{sub 4} composites and their application in oxidative desulfurization

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Rongxiang, E-mail: zylhzrx@126.com; Li, Xiuping, E-mail: lilili_171717@126.com; Su, Jianxun; Gao, Xiaohan

    2017-01-15

    Highlights: • The WO{sub 3}/g-C{sub 3}N{sub 4} was successfully synthesized through simple calcination. • The process is simple and the cost raw materials is cheap. • The WO{sub 3}/g-C{sub 3}N{sub 4} firstly applied to ODS. • The desulpurization rate of WO{sub 3}/g-C{sub 3}N{sub 4} may attach to 91.2%. • Five recycles of WO{sub 3}/g-C{sub 3}N{sub 4} still attach to 89.5% due to heterogeneous catalysis. - Abstract: WO{sub 3}/graphitic carbon nitride (g-C{sub 3}N{sub 4}) composites were successfully synthesized through direct calcining of a mixture of WO{sub 3} and g-C{sub 3}N{sub 4} at 400 °C for 2 h. The WO{sub 3} was prepared by calcination of phosphotungstic acid at 550 °C for 4 h, and the g-C{sub 3}N{sub 4} was obtained by calcination of melamine at 520 °C for 4 h. The WO{sub 3}/g-C{sub 3}N{sub 4} composites were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and Brunner−Emmett−Teller analysis (BET). The WO{sub 3}/g-C{sub 3}N{sub 4} composites exhibited stronger XRD peaks of WO{sub 3} and g-C{sub 3}N{sub 4} than the WO{sub 3} and pure g-C{sub 3}N{sub 4}. In addition, two WO{sub 3} peaks at 25.7° and 26.6° emerged for the 36% −WO{sub 3}/g-C{sub 3}N{sub 4} composite. This finding indicated that WO{sub 3} was highly dispersed on the surface of the g-C{sub 3}N{sub 4} nanosheets and interacted with the nanosheets, which resulted in the appearance of (012) and (022) planes of WO{sub 3}. The WO{sub 3}/g-C{sub 3}N{sub 4} composite also exhibited a larger specific surface area and higher degree of crystallization than WO{sub 3} or pure g-C{sub 3}N{sub 4}, which resulted in high catalytic activity of the catalyst. Desulfurization experiments demonstrated that the desulfurization rate of dibenzothiophene (DBT) in model oil reached 91.2% under optimal conditions. Moreover, the activity of the catalyst was not significantly decreased after five recycles.

  12. Luminescence and photothermally stimulated defects creation processes in PbWO4:La3+, Y3+ (PWO II) crystals

    International Nuclear Information System (INIS)

    Auffray, E.; Korjik, M.; Zazubovich, S.

    2015-01-01

    Photoluminescence and thermally stimulated luminescence (TSL) are studied for a PbWO 4 crystal grown by the Czochralski method at Bogoroditsk Technical Chemical Plant, Russia from the melt with a precise tuning of the stoichiometry and co-doped with La 3+ and Y 3+ ions (the PWO II crystal). Photothermally stimulated processes of electron and hole centers creation under selective UV irradiation of this crystal in the 3.5–5.0 eV energy range and the 85–205 K temperature range are clarified and the optically created electron and hole centers are identified. The electrons in PWO II are mainly trapped at the (WO 4 ) 2− groups located close to single La 3+ and Y 3+ ions, producing the electron {(WO 4 ) 3− –La 3+ } and {(WO 4 ) 3− –Y 3+ } centers. The holes are mainly trapped at the regular oxygen ions O 2− located close to La 3+ and Y 3+ ions associated with lead vacancies, producing the hole O − (I)-type centers. No evidence of single-vacancy-related centers has been observed in PWO II. The data obtained indicate that excellent scintillation characteristics of the PWO II crystal can be explained by a negligible concentration of single (non-compensated) oxygen and lead vacancies as the traps for electrons and holes, respectively. - Highlights: • Photoluminescence of the PbWO 4 :La 3+ , Y 3+ (PWO II) crystal is investigated. • Creation of defects under UV irradiation of PWO II is studied by TSL. • Origin of dominating electron and hole centers is ascertained. • Concentration of single-vacancy-related centers is found to be negligible. • Excellent scintillation characteristics of the PWO II crystal are explained.

  13. In situ observation of surface reactions with synchrotron radiation induced semiconductor processes by infrared reflection absorption spectroscopy using buried metal layer substrates; Umekomi kinzokuso kiban wo mochiita sekigai hansha kyushu supekutoruho ni yoru hoshako reiki handotai process hanno no sonoba kansatsu

    Energy Technology Data Exchange (ETDEWEB)

    Yoshigoe, A.; Hirano, S. [The Graduate University for Advanced Studies, Yokohama (Japan); Mase, K.; Urisu, T. [Institute for Molecular Science, Aichi (Japan)

    1996-11-20

    It is known that infrared reflection absorption spectroscopy (IRAS) on semiconductor or insulator surfaces becomes practicable by using buried metal layer (BML) substrates, in which the metal thin film is buried order semiconductor or insulator films. In this work, IRAS has been measured for Langmuir-Blodgett films deposited on the BML substrate with SiO2/Al/Si(100) structure and the observed spectrum intensity has been quantitatively compared with the calculation assuming the ideal multilayer structure for the BML substrate. The BML-IRAS using CoSi2 has been adopted to the detection of SiHn on the Si (100) substrate during synchrotron radiation (SR) stimulated Si2H6 gas source molecular beam epitaxy. It has been found that SiH2 and SiH3 on the Si (100) surface are easily decomposed by SR, but SiH can`t be decomposed. From these experiments, it has been concluded that the BML-IRAS is an useful in situ observation technique for the photo-stimulated surface reactions. 26 refs., 9 figs.

  14. Report on achievements in fiscal 1998. Research on acceleration of improving the base for biological resource information, and development of a technology to measure gene information (development of the DNA measuring technology using bead arrays); 1998 nendo seibutsu shigen joho kiban seibi kasokuka kenkyu idenshi joho no keisoku gijutsu no kaihatsu seika hokokusho. Bizu array wo mochiita DNA keisoku gijutsu no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    It is necessary in the field of post-genoms to know statistical correlation between DNA orientation information and clinical data, which helped growth of DNA probe arrays (DNA chips). However, it is difficult in patent point of view to develop chips in Japan. On the other hand, a movement has begun to use beads fixed with DNA probes in place of DNA chips demarcated on the surface of solids. This is a method to investigate hybridized DNA by means of fluorescent detection, in which each bead retaining the DNA probes is colored to make identification of the retained probes possible, and hybridizing reaction is performed in aqueous solution. Hitachi has developed a DNA measuring technology using bead arrays. The bead array has probe fixing beads of about 100 {mu} m laid sequentially inside a capillary, wherein the array can be used to inspect a large number of genes. Thus, this method can be a DNA measuring technology which is inexpensive, and high in reproducibility. These features lead to a belief that the technology is suitable for gene inspection devices used in the process of medicine development and at the clinical sites. (NEDO)

  15. Achievement report for fiscal 1981 on Sunshine Program research and development. Research and development of amorphous solar cells (Research and development of amorphous solar cells on flexible film substrates); 1981 nendo amorphous taiyo denchi no kenkyu kaihatsu seika hokokusho. Kadosei film wo kiban to suru amorphous taiyo denchi no kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1982-03-31

    Efforts will be made to reduce the cost, increase efficiency, and enlarge cell areas and, at the same time, to establish the foundation of a roll-up type solar cell manufacturing process which is required for the implementation of mass production. In an inverted pin/ITO (indium-tin oxide) hetero-face structure cell installed on a polymer film substrate, a conversion efficiency of 5.33% is achieved in the case of a solar cell whose n-layer is of the amorphous phase, and 6.36% in the case of a cell of the microcrystallized phase. A roll-up type glow discharge CVD (chemical vapor deposition) unit is designed and experimentally built, which is for the realization of large area cells. It is now duly expected that an undoped (i-type) a-Si:H film will be deposited to a thickness of approximately 5000A. As the result of a first-step screening conducted in search of amorphous solar cell sealing materials, some applicable plastic materials are selected. The future is bright of amorphous solar cells on polymer film substrates. (NEDO)

  16. Structure refinement of commensurately modulated bismuth tungstate, Bi2WO6

    International Nuclear Information System (INIS)

    Rae, A.D.; Thompson, J.G.; Withers, R.L.

    1991-01-01

    The displacive ferroelectric Bi 2 WO 6 [M r = 697.81, a = 5.4559 (4), b = 5.4360 (4), c = 16.4298 (17) A, Z = 4, D x = 9.512 g cm -3 , MoKα, λ = 0sun7107 A, μ = 958.6 cm -1 , F(000) = 1151.73], is described at room temperature as a commensurate modulation of an idealized Fmmm parent structure derived from an I4/mmm structure. Transmission electron microscopy clearly showed that there are coherent intergrowths of two distinct modulated variants in Bi 2 WO 6 crystals. Displacive models of inherent F2mm and Bmab symmetry are substantial and coherent over a large volume. They reduce the space-group symmetry to B2ab. A further substantial displacive mode corresponds to rotation of corner-connected WO 6 octahedra about axes parallel to c and has either of two inherent symmetries, Abam or Bbam, the difference being associated with the way this mode reduces the space-group symmetry to P2 1 ab, while the existence of the Bbam mode reduces the intensity of h + l = 2n + 1 data and acts like a stacking fault. Group theoretical analysis of the problem details how the X-ray data can be classified so as to monitor the refinement. Anomalous dispersion selects the overall sign of the F2mm mode and determines the polarity. The overall signs chosen for the Bmab and Abam symmetry components of atom displacements select between equivalent origins. The overall signs of induced modes of inherent Amam, Bbab and Ccma symmetry had to be determined by comparative refinement since the assumption that calculated phases are best estimates can retain the initial overall sign choice for these modes during least-squares refinement. Correlations between the dominant modes and the induced modes allowed a meaningful choice of signs to resolve the pseudo homometry. Only the sign of the Bbab mode was capable of self-correction during refinement. (orig./BHO)

  17. Critical difference between optoelectronic properties of α- and β-SnWO4semiconductors: A DFT/HSE06 and experimental investigation

    KAUST Repository

    Harb, Moussab; Ziani, Ahmed; Takanabe, Kazuhiro

    2016-01-01

    The optoelectronic properties of β-SnWO4 are investigated in details using experiments on thin film generated by rapid quenching and the first-principles quantum calculations based on the density functional theory (DFT, including the perturbation

  18. Solar photocatalytic activity of TiO{sub 2} modified with WO{sub 3} on the degradation of an organophosphorus pesticide

    Energy Technology Data Exchange (ETDEWEB)

    Ramos-Delgado, N.A. [Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, San Nicolás de los Garza, N.L. (Mexico); Gracia-Pinilla, M.A. [Universidad Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas, Av. Universidad, Cd. Universitaria, San Nicolás de los Garza, N.L. (Mexico); Universidad Autónoma de Nuevo León, Centro de Investigación e Innovación en Desarrollo de Ingeniería y Tecnología, PIIT Km 6, Carretera al Aeropuerto, Apodaca, N.L. (Mexico); Maya-Treviño, L.; Hinojosa-Reyes, L.; Guzman-Mar, J.L. [Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, San Nicolás de los Garza, N.L. (Mexico); Hernández-Ramírez, A., E-mail: aracely.hernandezrm@uanl.edu.mx [Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, San Nicolás de los Garza, N.L. (Mexico)

    2013-12-15

    Highlights: • TiO{sub 2} and WO{sub 3}/TiO{sub 2} (2 and 5%) were tested in the photocatalytic malathion degradation. • The use of solar radiation in the photocatalytic degradation process was evaluated. • Modified catalyst showed greater photocatalytic activity than pure TiO{sub 2}. • The mineralization rate was improved when WO{sub 3} content on TiO{sub 2} was 2%. -- Abstract: In this study, the solar photocatalytic activity (SPA) of WO{sub 3}/TiO{sub 2} photocatalysts synthesized by the sol–gel method with two different percentages of WO{sub 3} (2 and 5%wt) was evaluated using malathion as a model contaminant. For comparative purpose bare TiO{sub 2} was also prepared by sol–gel process. The powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectance UV–vis spectroscopy (DRUV–vis), specific surface area by the BET method (SSA{sub BET}), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy with a high annular angle dark field detector (STEM-HAADF). The XRD, Raman, HRTEM and STEM-HAADF analyses indicated that WO{sub 3} was present as a monoclinic crystalline phase with nanometric cluster sizes (1.1 ± 0.1 nm for 2% WO{sub 3}/TiO{sub 2} and 1.35 ± 0.3 nm for 5% WO{sub 3}/TiO{sub 2}) and uniformly dispersed on the surface of TiO{sub 2}. The particle size of the materials was 19.4 ± 3.3 nm and 25.6 ± 3 nm for 2% and 5% WO{sub 3}/TiO{sub 2}, respectively. The SPA was evaluated on the degradation of commercial malathion pesticide using natural solar light. The 2% WO{sub 3}/TiO{sub 2} photocatalyst exhibited the best photocatalytic activity achieving 76% of total organic carbon (TOC) abatement after 300 min compared to the 5% WO{sub 3}/TiO{sub 2} and bare TiO{sub 2} photocatalysts, which achieved 28 and 47% mineralization, respectively. Finally, experiments were performed to assess 2% WO{sub 3}/TiO{sub 2} catalyst activity on

  19. Gas Sensing Properties of Pure and Cr Activated WO3 Thick Film Resistors

    Directory of Open Access Journals (Sweden)

    V. B. GAIKWAD

    2010-09-01

    Full Text Available Thick films of WO3 (Tungsten Oxide were prepared by screen-printing techniques. The surfaces of the films were modified by dipping them into an aqueous solution of Chromium Oxide (CrO3 for different intervals of time, followed by firing at 550 oC for 30 min. The gas sensing performance of the pure and Cr2O3-modified films was tested for various gases at different temperatures. The unmodified films showed response to H2S, ethanol and cigar smoke. However Cr2O3- modified films suppresses gas sensing response to all gases except H2S. The surface modification, using dipping process, altered the adsorbate-adsorbent interactions, which gave the specific selectivity and enhanced sensitivity to H2S gas. The gas response, selectivity, thermal stability and recovery time of the sensor were measured and presented. The role played by surface chromium species to improve gas sensing performance is discussed.

  20. A pulsed single-frequency Nd:GGG/BaWO4 Raman laser

    Science.gov (United States)

    Liu, Zhaojun; Men, Shaojie; Cong, Zhenhua; Qin, Zengguang; Zhang, Xingyu; Zhang, Huaijin

    2018-04-01

    A single-frequency pulsed laser at 1178.3 nm was demonstrated in a crystalline Raman laser. A crystal combination of Nd:GGG and BaWO4 was selected to realize Raman conversion from a 1062.5 nm fundamental wave to a 1178.3 nm Stokes wave. An entangled cavity was specially designed to form an intracavity Raman configuration. Single-longitudinal-mode operation was realized by introducing two Fabry-Perot etalons into the Raman laser cavity. This laser operated at a pulse repetition rate of 50 Hz with 2 ms long envelopes containing micro pulses at a 30 kHz repetition rate. The highest output power was 41 mW with the micro pulse duration of 15 ns. The linewidth was measured to be less than 130 MHz.

  1. Preparation and characterisation of radiation hard PbWO4 crystal scintillator

    International Nuclear Information System (INIS)

    Sabharwal, S.C.; Desai, D.G.; Sangeeta; Karandikar, S.C.; Chauhan, A.K.; Sangiri, A.K.; Keshwani, K.S.; Ahuja, M.N.

    1996-01-01

    The selective loss of one of the crystal constituents is found to be responsible for the yellowish coloration of PbWO 4 crystals. However, using the already pulled crystals as the starting charge for the subsequent growth, colorless crystals can be grown. The crystals exhibiting excellent transmission characteristics have been grown employing a low temperature gradient, a moderate rotation rate of 15 rpm and a pull speed of 1 mm/h. The colored crystals show some radiation damage on gamma irradiation, while the colorless ones remain unaffected even for irradiation doses as high as 10 Mrad. Both the types of crystals show the presence of weak thermoluminescence (TL) emission when high irradiation doses (similar 10 Mrad) are given. Only one TL glow peak is obtained in both the cases but the peak temperatures are different. The emission centers responsible for the TL emission are found to be the ones which give rise to the scintillation emission in the crystal. (orig.)

  2. Separation of PbWO4 and BGO signals into Cerenkov and scintillation components

    International Nuclear Information System (INIS)

    Voena, C

    2009-01-01

    We present results from beam tests performed in 2007 on PbWO 4 and BGO crystals in the context of the DREAM project. Signals from high energy electrons and pions are analyzed and the possibility of separating the contributions from Cerenkov (C) and scintillation (S) light for individual events is investigated. Different methods exploiting the difference in timing, in the spectra and in the directionality of the two types of light have been developed to determine the contribution of the two components. In the BGO crystal, Cerenkov signals have been enhanced with the use of optical filters and the ratio C/S is measured with good precision (∼20-30% for energy deposits less than 1 GeV).

  3. Synthesis and characterization of novel red emitting nanocrystal Gd6WO12:Eu3+ phosphors

    International Nuclear Information System (INIS)

    Tian Yue; Chen Baojiu; Hua Ruinian; Zhong Haiyang; Cheng Lihong; Sun Jiashi; Lu Weili; Wan Jing

    2009-01-01

    Novel nanosized Gd 6 WO 12 :Eu 3+ phosphors were synthesized via a co-precipitation reaction. The crystal structure and morphology of the phosphors were characterized by using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). It was found that the resultant powders show a regular and sphere-like shape with average particle size of 60 nm. Intrinsic red emission originating from Eu 3+ was observed while excited at the W 6+ →O 2- and Eu 3+ →O 2- charge transfer bands or f-f absorption bands. The color coordinates of the phosphors were calculated to be x=0.625, y=0.375. The concentration dependence of the luminescence was studied, and optimum doping concentration for obtaining maximum emitting intensity was confirmed to be around 12 mol%. It was also found that the electric dipole-dipole interaction plays an important role for quenching luminescence of Eu 3+ .

  4. TEM and AFM study of WO3 nanosize growth on α-Al2O3

    International Nuclear Information System (INIS)

    Al-Mohammad, A.

    2007-07-01

    WO 3 thin films have been deposited by thermal evaporation on (0001) and (1012 ) planes of alumina oxide single crystal and annealed either in Oxygen or in air atmosphere. The morphology and crystallographic structure of films (as-deposited and annealed films) have been characterized by Atomic Force Microscope (AFM), transmission electron microscope (TEM), and transmission electron diffraction (TED). During annealing, the films undergo important morphological and structural changes. The annealed films exhibit large grains. These grains have the monoclinic structure in epitaxial orientations. The grains are made of twinned microdomains elongated in the [100] direction resulting of a preferential growth. The microdomains are along the three different directions on the (0001) α-Al 2 O 3 surface and only one direction on the (1012 ) α-Al 2 O 3 one.(author)

  5. Growth and optical property of ZnWO4: Er3+ crystal

    International Nuclear Information System (INIS)

    Yang Fugui; Tu Chaoyang; Li Jianfu; Jia Guohua; Wang Hongyan; Wei Yanping; You Zhenyu; Zhu Zhaojie; Wang Yan; Lu Xiuai

    2007-01-01

    Good quality crystals ZnWO 4 activated with Er 3+ have been grown by means of Czochralski method and characterized using optical spectroscopy techniques. XRD, absorption spectra, fluorescence spectrum are presented and the Judd-Ofelt intensity parameters Ω 2 , Ω 4 , and Ω 6 are obtained to be 6.76x10 -20 , 0.37x10 -20 , and 0.50x10 -20 cm 2 , respectively. Along crystallographic axes, refractive indices are presented. The fluorescence decay time of the 4 I 13/2 level has also been investigated and shows an exponential behavior with a lifetime value of 5.52 ms. The crystal is potentially used for green and infrared eye-safe lasers

  6. Structure and properties of TeO2-WO3 system glasses

    International Nuclear Information System (INIS)

    Kolobkov, V.P.; Ovcharenko, N.V.; Morozova, I.N.; Chebotarev, S.A.; Chikovskij, A.N.; Arkatova, T.G.

    1987-01-01

    Study of TeO 2 -WO 3 system is of interest for production of high-refractive-glasses with comparatively low crystallizability. Results of investigating some properties and structural features of this system glasses are presented. Composition and properties of studied glasses are presented. The properties were studied using the following techniques: the density was measured by hydrostatic weighing in toluene; thermal expansion coefficient was measured in quartz dilatometer DKV-5A; dilatometric temperature of glass softening (T g ) was defined as an intersection point of linear and curved parts of the plot of thermal expansion coefficient; refractive index (RI) - by immersion method; dielectric properties are measured. Consideration of vibronic spectra permits to conclude that in tungsten-tellurium glasses rare earth activator ions are arranged near tellurite and tungstate groupings proportional to glass-forming component content

  7. Synthesis and characterization of LnAg(WO{sub 4})(MoO{sub 4})

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Martinez, F. [Universidad Politecnica de Madrid, E.U.I.T. Industrial, Ronda de Valencia 3, 28012 Madrid (Spain)], E-mail: francisco.fernandezm@upm.es; Colon, C.; Montero, J.L.; Atanes, E. [Universidad Politecnica de Madrid, E.U.I.T. Industrial, Ronda de Valencia 3, 28012 Madrid (Spain); Rivero, C. [Universidad Politecnica de Madrid, E.T.S.I. Telecomunicaciones, Avda. Complutense s/n, Ciudad Universitaria, 28040 Madrid (Spain)

    2008-02-28

    Polycrystalline LnAg(WO{sub 4})(MoO{sub 4}) powders, with Ln = La to Lu and Y, have been obtained by ceramic method. Rietveld refinement for all compounds reveals that they present tetragonal symmetry, space group I4{sub 1}/a (No. 88), where the Ln{sup 3+}/Ag{sup +} ions are located in the 4a atomic positions, since the W/Mo are randomly distributed into 4b crystal sites. In these compounds, a and b lattice parameters take values between those corresponding to tungstate and molybdate compounds. A progressive decrease in the lattice parameters is observed in going from La to Lu derivatives as a consequence of the well-known lanthanide contraction.

  8. Cosmic ray calibration of the PbWO4 crystal electromagnetic calorimeter of CMS

    International Nuclear Information System (INIS)

    Franzoni, G.

    2006-01-01

    The Compact Muon Solenoid experiment at the CERN LHC features a high precision PbWO4 crystal electromagnetic calorimeter. Each crystal is first precalibrated with a radioactive source and by means of optical measurements. After the assembly, each supermodule (1700 crystals) is exposed to comics rays.The comparison between intercalibration obtained from cosmic muons and electrons from test beam was performed at the end of 2004 for an initial set of 130 channels and showed that a precalibration with a statistical precision of 1 to 2% can be achieved within approximately one week. An important aspect of the comics muons analysis is that it is entirely based on the calorimeter data, without using any external tracking device.We will present the setup and results from the 2004 test as well as recent data recorded on many supermodule

  9. Further understanding of PbWO4 Scintillator characteristics and their optimisation. LUMEN activity in 1998

    CERN Document Server

    Baccaro, Stefania; Borgia, Bruno; Cecilia, Angelica; Dafinei, Ioan; Diemoz, Marcella; Fabeni, P; Festinesi, Armando; Longo, Egidio; Martini, M; Meinardi, F; Mihoková, E; Montecchi, Marco; Nikl, M; Pazzi, G P; Rosa, J; Sulc, Miroslav

    2000-01-01

    The aim of LUMEN collaboration was the investigation on single crystals of PbWO4 ( PWO): the results performed up to now provide the evidence of the possibility to optimise the optical properties of an intrinsic scintillator such as PWO. The control of essential requirements in the crystal preparation ( raw material purity, growing methods and post-growth annealing) as well as the introduction of selected dopants at suitable concentrations ( particularly trivalent and pentavalent ions) were found to be very successful in lowering the concentration of point defects in the lattice which strongly affect scintillation properties and radiation hardness. The systematic investigation effort to better understand the scintillation characteristics and to improve the quality of PWO crystals is due to their use for the CMS electromagnetic calorimeter.

  10. Investigation the physicochemical properties and stability of w/o emulsion

    International Nuclear Information System (INIS)

    Iqbal, S.; Baloch, M.K.; Hameed, G.

    2014-01-01

    The study aims to investigate the stability of W/O emulsions with respect to coalescence time. The various concentrations of water were dispersed in oil phase (soybean oil). The compositions of organic and aqueous phases were varied by adding emulsifier (Monoglyceride), sodium chloride and thickening agent (mango's pulp). The technique employed for the mixing of two phases was homogenization. The Emulsion Stability Index (ESI), Viscosity changes, separation of organic and aqueous phases as a function of storage time have been studied. It has been found that monoglyceride increases the stability and decreases the emulsion stability index (ESI) and also decreases the viscosity changes with storage time while electrolytes and mango's pulp encourage the coalescence process and enhance the instability of the system. On the other hand the system that contained all the organic and aqueous ingredients showed high stability. (author)

  11. Exploration on anion ordering, optical properties and electronic structure in K{sub 3}WO{sub 3}F{sub 3} elpasolite

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V.V. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Isaenko, L.I. [Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 630090 (Russian Federation); Kesler, V.G. [Laboratory of Physical Principles for Integrated Microelectronics, Institute of Semiconductor Physics, Novosibirsk 630090 (Russian Federation); Lin, Z.S., E-mail: zslin@mail.ipc.ac.cn [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, P.O. Box 2711, Beijing 100190 (China); Molokeev, M.S. [Laboratory of Crystal Physics, Institute of Physics, SB RAS, Krasnoyarsk 660036 (Russian Federation); Yelisseyev, A.P.; Zhurkov, S.A. [Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 630090 (Russian Federation)

    2012-03-15

    Room-temperature modification of potassium oxyfluorotungstate, G2-K{sub 3}WO{sub 3}F{sub 3}, has been prepared by low-temperature chemical route and single crystal growth. Wide optical transparency range of 0.3-9.4 {mu}m and forbidden band gap E{sub g}=4.32 eV have been obtained for G2-K{sub 3}WO{sub 3}F{sub 3} crystal. Meanwhile, its electronic structure has been calculated with the first-principles calculations. The good agreement between the theorectical and experimental results have been achieved. Furthermore, G2-K{sub 3}WO{sub 3}F{sub 3} is predicted to possess the relatively large nonlinear optical coefficients. - Graphical abstract: Using the cm-size K{sub 3}WO{sub 3}F{sub 3} crystal (left upper), the transmission spectrum (right upper) and XPS valence electronic states (left lower) were measured, agreed with the ab initio results (right lower). Highlights: Black-Right-Pointing-Pointer The cm-size G2-K{sub 3}WO{sub 3}F{sub 3} single crystals are obtained. Black-Right-Pointing-Pointer Optical absorption edge and transmission range are defined for G2-K{sub 3}WO{sub 3}F{sub 3} crystal. Black-Right-Pointing-Pointer Crystal structures of all known K{sub 3}WO{sub 3}F{sub 3} polymorph modifications are determined. Black-Right-Pointing-Pointer Experimental electronic structure is consistent with the first-principles result. Black-Right-Pointing-Pointer G2-K{sub 3}WO{sub 3}F{sub 3} is predicted as a crystal with large NLO coefficients.

  12. Facile preparation of Z-scheme WO{sub 3}/g-C{sub 3}N{sub 4} composite photocatalyst with enhanced photocatalytic performance under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Lifeng, E-mail: lifeng.cui@gmail.com [School of Chemistry and Environmental Engineering, Dongguan University of Technology, Guangdong 523808 (China); Ding, Xiang; Wang, Yangang; Shi, Huancong; Huang, Lihua; Zuo, Yuanhui [Department of Environmental Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Kang, Shifei, E-mail: sfkang@usst.edu.cn [Department of Environmental Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China)

    2017-01-01

    Highlights: • WO{sub 3}/g-C{sub 3}N{sub 4} composites were synthesized through a facile mixing-and-heating method. • The composite showed improved visible light response. • The composite showed high activity for MB degradation. • Z-scheme charge carrier transfer pathways in the composite are proposed. - Abstract: Visible-light-driven WO{sub 3}/g-C{sub 3}N{sub 4} composites photocatalysts were synthesized via a facile one-step simultaneously heating procedure with urea as the main precursor. These prepared catalyst samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG), transmission electron microscopy (TEM), N{sub 2} adsorption, ultraviolet-visible diffuse reflection spectroscopy (UV–vis), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and electrochemical impedance spectroscopy (EIS). The photocatalytic activity of the WO{sub 3}/g-C{sub 3}N{sub 4} composites was evaluated by the photo-degradation of Rhodamine B (RhB) under visible light irradiation. The results indicated that the composites with 25 wt.% WO{sub 3} content exhibited highest photocatalytic activity compared to pure WO{sub 3}, bare g-C{sub 3}N{sub 4} and other WO{sub 3}/g-C{sub 3}N{sub 4} composites. The favorable photocatalytic activity of WO{sub 3}/g-C{sub 3}N{sub 4} composites was mainly attributed to the excellent surface properties, enhanced visible-light absorption and the desirable band positions. A possible Z-scheme photocatalytic mechanism was proposed based on structure and electrochemical characterizations results, which can well explain the enhanced migration rate of photogenerated electrons and holes in WO{sub 3}/g-C{sub 3}N{sub 4} heterojunctions.

  13. A Preliminary Study on WO3‐Infiltrated W–Cu–ScYSZ Anodes for Low Temperature Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain; Reddy Sudireddy, Bhaskar; Høgh, Jens Valdemar Thorvald

    2012-01-01

    of symmetric cells were prepared by screen printing of WO3–CuO–ScYSZ ink and subsequent sintering at 1,300 °C for 1 h in 9% H2/N2. Analysis of the sintered backbone by X‐ray diffraction showed the metallic W and Cu phases. Precursor solutions of WO3 or CuO were infiltrated into porous WCS backbones to form...

  14. Three-dimensional Ag{sub 2}O/WO{sub 3}·0.33H{sub 2}O heterostructures for improving photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    He, Xiaoyu [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Department of Physics and Electronic Engineering, Yangtze Normal University, Chongqing 408100 (China); Hu, Chenguo, E-mail: hucg@cqu.edu.cn [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Xi, Yi; Zhang, Kaiyou; Hua, Hao [Department of Applied Physics, Chongqing University, Chongqing 400044 (China)

    2014-02-01

    Highlights: • Ag{sub 2}O/WO{sub 3}·0.33H{sub 2}O 3D network heterostructures are prepared via a simple precipitatation method. • Ag{sub 2}O/WO{sub 3}·0.33H{sub 2}O networks exhibit much enhanced photocatalytic activity. • High photocatalytic activity is attributed to its heterostructure and 3D architectures. - Abstract: Three-dimensional Ag{sub 2}O/WO{sub 3}·0.33H{sub 2}O heterostructures were fabricated by loading Ag{sub 2}O nanoparticles on WO{sub 3}·0.33H{sub 2}O 3D networks via a simple chemical precipitation method. The Ag{sub 2}O/WO{sub 3}·0.33H{sub 2}O heterostructures exhibited much enhanced photocatalytic activity for the degradation of methylene blue (MB) under simulated solar light irradiation. The optimal molar ratio of Ag{sub 2}O and WO{sub 3}·0.33H{sub 2}O is 1:2. The outstanding photocatalytic activity of the Ag{sub 2}O/WO{sub 3}·0.33H{sub 2}O can be attributed to its large surface area of the three-dimensional networks, the enhanced sunlight absorption and the prevention of electrons–holes combination from the heterostructures. The experiment result demonstrates that wide band gap semiconductor (WO{sub 3}·0.33H{sub 2}O) modified by narrow band gap metal oxide (Ag{sub 2}O) with 3D architecture will be an effective route to enhance its photocatalytic activity.

  15. PEGylated (NH4)xWO3 nanorods as efficient and stable multifunctional nanoagents for simultaneous CT imaging and photothermal therapy of tumor.

    Science.gov (United States)

    Macharia, Daniel K; Tian, Qiyun; Chen, Liang; Sun, Yingqi; Yu, Nuo; He, Chuanglong; Wang, Han; Chen, Zhigang

    2017-09-01

    The simultaneous imaging and photothermal therapy of tumors have attracted much attention, and a prerequisite is to obtain multifunctional nanomaterials. Ideally, one kind of nanoparticles with single component can be used as both imaging agent and photothermal agent. Herein, we have developed the PEGylated (NH 4 ) x WO 3 (denoted as (NH 4 ) x WO 3 -PEG) nanorods as multifunctional nanoparticles with single semiconductor component. (NH 4 ) x WO 3 -PEG nanorods with about 30nm diameter and length of several hundred nanometers have been obtained through a solvothermal synthesis-PEGylation two-step route. Under the irradiation of 980-nm laser with intensity of 0.72Wcm -2 , aqueous dispersion of (NH 4 ) x WO 3 -PEG nanorods (0.67-5.44mmol/L) displays high elevation (17.6-34.5°C) of temperature in 400s, accompanied by an excellent long-term photothermal stability. Furthermore, (NH 4 ) x WO 3 -PEG nanorods exhibit as high as 6 times X-ray attenuation ability compared to that of the clinically used iodine-based X-ray computed tomography (CT) contrast agent (Iopromide). More importantly, after PBS solution of (NH 4 ) x WO 3 -PEG nanorods is injected into the tumor of mice, the tumor can be effectively detected by CT imaging. Moreover, cancer cells in vivo can be further destroyed by the photothermal effects of (NH 4 ) x WO 3 -PEG nanorods, under the irradiation of 980-nm laser with the safe intensity of 0.72Wcm -2 for 10min. Therefore, (NH 4 ) x WO 3 -PEG nanorods can be used as a new kind of stable and efficient multifunctional nanoagent with single component for simultaneous CT imaging and photothermal therapy of tumor. Copyright © 2017. Published by Elsevier B.V.

  16. Low-temperature liquid-phase epitaxy and optical waveguiding of rare-earth-ion-doped KY(WO4)2 thin layers

    NARCIS (Netherlands)

    Romanyuk, Y.E.; Utke, I.; Ehrentraut, D.; Apostolopoulos, V.; Pollnau, Markus; Garcia-Revilla, S.; Valiente, B.

    2004-01-01

    Crystalline $KY(WO_{4})_{2}$ thin layers doped with different rare-earth ions were grown on b-oriented, undoped $KY(WO_{4})_{2}$ substrates by liquid-phase epitaxy employing a low-temperature flux. The ternary chloride mixture of NaCl, KCl, and CsCl with a melting point of 480°C was used as a

  17. A novel nitrite biosensor based on the direct electron transfer hemoglobin immobilized in the WO{sub 3} nanowires with high length–diameter ratio

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hui, E-mail: liuhui@sust.edu.cn; Duan, Congyue; Yang, Chenhui; Chen, Xianjin; Shen, Wanqiu; Zhu, Zhenfeng

    2015-08-01

    WO{sub 3} nanowires (WO{sub 3}NWs) with high length–diameter ratio have been synthesized through a simple synthetic route without any additive and then used to immobilize hemoglobin (Hb) to fabricate a mediator-free biosensor. The morphology and structure of WO{sub 3}NWs were characterized by scanning electron microscopy, transmission electronic microscopy and X-ray diffraction. Spectroscopic and electrochemical results revealed that WO{sub 3}NWs are an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. Meanwhile, due to unique morphology and property of the WO{sub 3} nanowires, the direct electron transfer of Hb is facilitated and the prepared biosensors displayed good performance for the detection of nitrite with a wide linear range of 1 to 4200 μM, as well as an extremely low detection limit of 0.28 μM. The WO{sub 3} nanowires with high length–diameter ratio could be a promising matrix for the fabrication of mediator-free biosensors, and may find wide potential applications in environmental analysis and biomedical detection. - Highlights: • The WO{sub 3}NWs with high length–diameter ratio have been synthesized. • The WO{sub 3}NWs were used to immobilize Hb to fabricate a mediator-free biosensor. • The biosensor displays a wide linear range of 1–4200 μM for nitrite. • The biosensor exhibits an extremely low detection limit of 0.28 μM for nitrite.

  18. Growth, spectroscopy and laser operation of Ho:KY(WO{sub 4}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Jambunathan, V. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n. E-43007 Tarragona (Spain); HiLASE Centre, Institute of Physics ASCR, Za Radnicí 828, 25241 Dolní Břežany (Czech Republic); Mateos, X., E-mail: xavier.mateos@urv.cat [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n. E-43007 Tarragona (Spain); Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 2A Max-Born-Str., D-12489 Berlin (Germany); Loiko, P.A. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n. E-43007 Tarragona (Spain); Center for Optical Materials and Technologies, Belarusian National Technical University, 65/17 Nezavisimosti Ave., 220013 Minsk (Belarus); Serres, J.M. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n. E-43007 Tarragona (Spain); Griebner, U.; Petrov, V. [Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 2A Max-Born-Str., D-12489 Berlin (Germany); Yumashev, K.V. [Center for Optical Materials and Technologies, Belarusian National Technical University, 65/17 Nezavisimosti Ave., 220013 Minsk (Belarus); and others

    2016-11-15

    Monoclinic Ho:KY(WO{sub 4}){sub 2} crystals doped with up to 7.5 at.% Ho are grown by the Top Seeded Solution Growth-Slow Cooling method. The evolution of their unit cell parameters in dependence on the Ho doping and temperature is studied. The polarized low-temperature (6 K) optical absorption of the Ho{sup 3+} ion is investigated in detail to determine the energy of the Stark sub-levels. Room-temperature absorption, stimulated-emission and gain cross-section spectra of Ho:KY(WO{sub 4}){sub 2} crystals are derived for polarizations parallel to the principal optical axes, E||N{sub p}, N{sub m} and N{sub g}. The maximum absorption cross-section for the {sup 5}I{sub 8}→{sup 5}I{sub 7} transition is 1.60×10{sup −20} cm{sup 2} at 1961.0 nm and the maximum stimulated-emission cross-section for the {sup 5}I{sub 7}→{sup 5}I{sub 8} transition is 2.65×10{sup −20} cm{sup 2} at 2056.3 nm (for E||N{sub m}). The radiative lifetime of the upper laser level of the Ho{sup 3+} ion ({sup 5}I{sub 7}) amounts to 4.8 ms. Continuous-wave Ho{sup 3+} laser operation is achieved under in-band pumping by a Tm laser at 1946 nm. In the microchip configuration, the maximum output power reached 205 mW at 2105 nm with a slope efficiency as high as 85%.

  19. A new polar symmetry of huebnerite (MnWO{sub 4}) with ferrodistortive domains

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.H., E-mail: sohyun.park@lmu.de [Sektion Kristallographie, Department für Geo-und Umweltwissenschaften, Ludwig-Maximilians-Universität München, Theresienstraße 41, 80333 München (Germany); Mihailova, B. [Mineralogisch-Petrographisches Institut, Universität Hamburg, Grindelallee 48, 20146 Hamburg (Germany); Pedersen, B. [Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München, Lichtenbergstraße 1, 85748 Garching (Germany); Paulmann, C. [Mineralogisch-Petrographisches Institut, Universität Hamburg, Grindelallee 48, 20146 Hamburg (Germany); HASYLAB, DESY, Notkestr. 85, 22603 Hamburg (Germany); Behal, D. [Sektion Kristallographie, Department für Geo-und Umweltwissenschaften, Ludwig-Maximilians-Universität München, Theresienstraße 41, 80333 München (Germany); Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München, Lichtenbergstraße 1, 85748 Garching (Germany); Gattermann, U. [Sektion Kristallographie, Department für Geo-und Umweltwissenschaften, Ludwig-Maximilians-Universität München, Theresienstraße 41, 80333 München (Germany); Hochleitner, R. [Mineralogische Staatssammlung München, Theresienstrasse 41, 80333 Munich (Germany)

    2015-11-15

    Large-size single-crystal samples of huebnerite natural multiferroic MnWO{sub 4} were analyzed by neutron and synchrotron X-ray single-crystal diffraction as well as by polarized Raman spectroscopy. Both neutron and X-ray diffraction analyzes reveal polar space-group symmetry P2 for the nuclear structure of huebnerite via the detection of weak reflections h0l (l=odd) forbidden for the gliding plane c. Renninger scans of the reflection 301 on the neutron single-crystal diffractometer RESI (FRM-II) could confirm the absence of the gliding plane c in both para- and antiferromagnetic states of huebnerite. The symmetry breaking could be explained by structure analyzes with neutron single crystal diffraction data at 293 K revealing that two Mn atoms in P2 are displaced independently along the b axis from their equilibrium position at a polar point site, C{sub 2} in P2/c. Micro X-ray diffraction and Raman-scattering mapping reveal a ferrodistortive domain texture in the room-temperature paramagnetic state of huebnerite, which is attributed to P2 domain formation through a proper ∼180° rotation about the reciprocal-space axis c*. - Graphical abstract: Schematic presentation of polar atomic shifts (arrows) in P2 from the respective equivalent sites (spheres) in P2/c at the boundary of two 180°-in-plane micro twins. - Highlights: • Neutron and X-ray diffraction analyzes reveal the polar symmetry P2 for MnWO{sub 4}. • Raman mapping shows ferrodistortive domains in its RT paramagnetic state. • These observations are explained by the hidden polar site C{sub 2} for Mn atoms.

  20. Synthesis, characterization and photocatalytic activity of WO3/TiO2 for NO removal under UV and visible light irradiation

    International Nuclear Information System (INIS)

    Luévano-Hipólito, E.; Martínez-de la Cruz, A.; López-Cuellar, E.; Yu, Q.L.; Brouwers, H.J.H.

    2014-01-01

    Samples with different proportions WO 3 /TiO 2 were prepared by co-precipitation method followed by a heat treatment. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), and adsorption–desorption N 2 isotherms (BET). The photocatalytic properties of WO 3 /TiO 2 samples were evaluated in the photo-oxidation reaction of nitric oxide (NO) under UV and visible light irradiation. The highest photocatalytic activity was observed in the WO 3 /TiO 2 sample with a composition of 80% mole of TiO 2 . Among the different substrates used for supporting the photocatalyst, the best results were reached over concrete and glass when it was exposed to UV and visible light irradiation, respectively. In overall, the photocatalytic efficiency of the synthesized materials was higher under UV than visible light irradiation. - Highlights: • WO 3 /TiO 2 prepared in simple way show high photocatalytic activity for NO removal. • The concrete was the best substrate to the performance of WO 3 /TiO 2 with UV radiation. • The glass was the best substrate to the performance of WO 3 /TiO 2 with visible radiation

  1. Structural, vibrational, and gasochromic properties of porous WO sub 3 films templated with a sol-gel organic-inorganic hybrid

    CERN Document Server

    Opara-Krasovec, U; Orel, B; Grdadolnik, J; Drazic, G

    2002-01-01

    The structure and the gasochromic properties of sol-gel-derived WO sub 3 films with a monoclinic structure (m-WO sub 3) were studied by focusing attention on the size of the monoclinic grains. The size of the m-WO sub 3 grains is modified by the addition of an organic-inorganic hybrid to the initial peroxopolytungstic acid (W-PTA) sols which are based on chemically bonded poly-(propylene glycol) to triethoxysilane end-capping groups (ICS-PPG). The results obtained with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the heat treatment (500 sup o C) of WO sub 3 /ICS- IPG (0.5, 1, 2, 5, and 10 mol%) composite films results in a change of their morphology, and nanodimensional pores are formed between the grains. High-resolution TEM (HRTEM) analysis revealed the presence of an amorphous phase on the outside of the m-WO sub 3 grains, whereas energy-dispersive x-ray spectra (EDXS) showed that this amorphous phase contained W and Si. Impregnation of the WO sub 3 /ICS-PPG film ...

  2. Ag2WO4 nanorods decorated with AgI nanoparticles: Novel and efficient visible-light-driven photocatalysts for the degradation of water pollutants

    Directory of Open Access Journals (Sweden)

    Shijie Li

    2018-04-01

    Full Text Available To develop efficient and stable visible-light-driven (VLD photocatalysts for pollutant degradation, we synthesized novel heterojunction photocatalysts comprised of AgI nanoparticle-decorated Ag2WO4 nanorods via a facile method. Various characterization techniques, including XRD, SEM, TEM, EDX, and UV–vis DRS were used to investigate the morphology and optical properties of the as-prepared AgI/Ag2WO4 catalyst. With AgI acting as the cocatalyst, the resulting AgI/Ag2WO4 heterostructure shows excellent performance in degrading toxic, stable pollutants such as rhodamine B (RhB, methyl orange (MO and para-chlorophenol (4-CP. The high performance is attributed to the enhanced visible-light absorption properties and the promoted separation efficiency of charge carriers through the formation of the heterojunction between AgI and Ag2WO4. Additionally, AgI/Ag2WO4 exhibits durable stability. The active species trapping experiment reveals that active species (O2•− and h+ dominantly contribute to RhB degradation. The AgI/Ag2WO4 heterojunction photocatalyst characterized in this work holds great potential for remedying environmental issues due to its simple preparation method and excellent photocatalytic performance.

  3. Preparation of Er3+:Y3Al5O12/WO3-KNbO3 composite and application in treatment of methamphetamine under ultrasonic irradiation.

    Science.gov (United States)

    Zhang, Hongbo; Huang, Yingying; Li, Guanshu; Wang, Guowei; Fang, Dawei; Song, Youtao; Wang, Jun

    2017-03-01

    Er 3+ :Y 3 Al 5 O 12 /WO 3 -KNbO 3 composite powder as an effective sonocatalyst was prepared via collosol-gelling-hydrothermal and high-temperature calcination methods. The textures of materials were observed by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). In order to estimate the sonocatalytic activity of Er 3+ :Y 3 Al 5 O 12 /WO 3 -KNbO 3 composite powder, the sonocatalytic degradation of methamphetamine (MAPA) was performed. Furthermore, the influences of mass ratio of WO 3 and KNbO 3 , ultrasonic irradiation time, catalyst addition amount, initial methamphetamine (MAPA) concentration and used times on the sonocatalytic degradation of methamphetamine (MAPA) caused by Er 3+ :Y 3 Al 5 O 12 /WO 3 -KNbO 3 composite powder were investigated by using gas chromatography. Under optimal conditions of 1.00g/L Er 3+ :Y 3 Al 5 O 12 /WO 3 -KNbO 3 addition amount and 10.00mg/L methamphetamine (MAPA) initial concentration, 68% of methamphetamine (MAPA) could be removed after 150min ultrasonic irradiation. The experimental results showed that the Er 3+ :Y 3 Al 5 O 12 /WO 3 -KNbO 3 as sonocatalyst displayed an excellent sonocatalytic activity in degradation of methamphetamine (MAPA) under ultrasonic irradiation. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. A novel biosensor based on the direct electrochemistry of horseradish peroxidase immobilized in the three-dimensional flower-like Bi_2WO_6 microspheres

    International Nuclear Information System (INIS)

    Liu, Hui; Guo, Kai; Duan, Congyue; Chen, Xianjin; Zhu, Zhenfeng

    2016-01-01

    Three-dimensional flower-like Bi_2WO_6 microspheres (3D-Bi_2WO_6 MSs) have been synthesized through a simple hydrothermal method. The morphology and structure of 3D-Bi_2WO_6 MSs were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The 3D-Bi_2WO_6 MSs subsequently were used to immobilize horseradish peroxidase (HRP) and fabricate a mediator-free biosensor for the detection of H_2O_2. Spectroscopic and electrochemical results reveal that 3D-Bi_2WO_6 MSs constitute an excellent immobilization matrix with biocompatibility for enzymes. Meanwhile, due to unique morphology of the flower-like microspheres, the direct electron transfer of HRP is facilitated and the prepared biosensors display good performances for the detection of H_2O_2 with a wide linear range, including two linear sections: 0.5–100 μM (R"2 = 0.9983) and 100–250 μM (R"2 = 0.9981), as well as an extremely low method detection limit of 0.18 μM. - Highlights: • 3D-Bi_2WO_6 microspheres are used to fabricate a mediator-free biosensor firstly. • The biosensor displays a wide linear range of 0.5–250 μM for H_2O_2. • The biosensor exhibits a low detection limit of 0.18 μM for H_2O_2.

  5. Synthesis, characterization and photocatalytic activity of WO{sub 3}/TiO{sub 2} for NO removal under UV and visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Luévano-Hipólito, E. [CIIDIT, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Martínez-de la Cruz, A., E-mail: azael.martinezdl@uanl.edu.mx [CIIDIT, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); López-Cuellar, E. [CIIDIT, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Yu, Q.L.; Brouwers, H.J.H. [Department of the Built Environment, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2014-11-14

    Samples with different proportions WO{sub 3}/TiO{sub 2} were prepared by co-precipitation method followed by a heat treatment. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), and adsorption–desorption N{sub 2} isotherms (BET). The photocatalytic properties of WO{sub 3}/TiO{sub 2} samples were evaluated in the photo-oxidation reaction of nitric oxide (NO) under UV and visible light irradiation. The highest photocatalytic activity was observed in the WO{sub 3}/TiO{sub 2} sample with a composition of 80% mole of TiO{sub 2}. Among the different substrates used for supporting the photocatalyst, the best results were reached over concrete and glass when it was exposed to UV and visible light irradiation, respectively. In overall, the photocatalytic efficiency of the synthesized materials was higher under UV than visible light irradiation. - Highlights: • WO{sub 3}/TiO{sub 2} prepared in simple way show high photocatalytic activity for NO removal. • The concrete was the best substrate to the performance of WO{sub 3}/TiO{sub 2} with UV radiation. • The glass was the best substrate to the performance of WO{sub 3}/TiO{sub 2} with visible radiation.

  6. Highly efficient perovskite solar cells based on a nanostructured WO3-TiO2 core-shell electron transporting material

    KAUST Repository

    Mahmood, Khalid; Swain, Bhabani Sankar; Kirmani, Ahmad R.; Amassian, Aram

    2015-01-01

    Until recently, only mesoporous TiO2 and ZnO were successfully demonstrated as electron transport layers (ETL) alongside the reports of ZrO2 and Al2O3 as scaffold materials in organometal halide perovskite solar cells, largely owing to ease of processing and to high power conversion efficiency. In this article, we explore tungsten trioxide (WO3)-based nanostructured and porous ETL materials directly grown hydrothermally with different morphologies such as nanoparticles, nanorods and nanosheet arrays. The nanostructure morphology strongly influences the photocurrent and efficiency in organometal halide perovskite solar cells. We find that the perovskite solar cells based on WO3 nanosheet arrays yield significantly enhanced photovoltaic performance as compared to nanoparticles and nanorod arrays due to good perovskite absorber infiltration in the porous scaffold and more rapid carrier transport. We further demonstrate that treating the WO3 nanostructures with an aqueous solution of TiCl4 reduces charge recombination at the perovskite/WO3 interface, resulting in the highest power conversion efficiency of 11.24% for devices based on WO3 nanosheet arrays. The successful demonstration of alternative ETL materials and nanostructures based on WO3 will open up new opportunities in the development of highly efficient perovskite solar cells. This journal is © The Royal Society of Chemistry 2015.

  7. Solar light-facilitated oxytetracycline removal from the aqueous phase utilizing a H2O2/ZnWO4/CaO catalytic system

    Directory of Open Access Journals (Sweden)

    Pankaj Raizada

    2017-09-01

    Full Text Available A CaO-supported ZnWO4 nanocomposite (ZnWO4/CaO was successfully synthesized using a novel hydrothermal method and was characterized by scanning electron microscopy (SEM, tunnelling electron microscopy (TEM, X-ray diffraction (XRD, electron diffraction X-ray (EDX, Fourier transform infrared spectroscopy (FTIR and UV–visible (UV–vis spectral analysis. The ZnWO4/CaO composites exhibited rod-like morphologies with variable lengths from 45 nm to 147 nm and diameters from 26 nm to 36 nm. The catalytic efficiency of the synthesized ZnWO4/CaO composites was displayed for the photodegradation of oxytetracycline (OTC antibiotic from the aqueous phase. The synergistic degradation of OTC was investigated in the presence of H2O2 and ZnWO4/CaO. The rate of photodegradation followed pseudo-first-order kinetics. The antibiotic removal was strongly influenced by the catalyst loading, H2O2 concentration, pH and OTC concentration. Using a solar/H2O2/ZnWO4/CaO catalytic system, 85% COD removal was attained for OTC degradation in 210 min. The oxidative degradation occurred through hydroxyl radicals. The prepared nanocomposites possessed high recyclability and were easily separated from the aqueous solution by a simple sedimentation process.

  8. Sol-gel synthesis of Bi2WO6/graphene thin films with enhanced photocatalytic performance for nitric monoxide oxidation under visible light irradiation

    Science.gov (United States)

    Sun, Chufeng; Wang, Yanbin; Su, Qiong

    2018-06-01

    Bi2WO6 and Bi2WO6/graphene thin films were fabricated by spin coating and post annealing at 600 °C for 2 h. In four different thin film samples, the graphene concentration was controlled as 0, 2, 4 and 6 wt%, respectively. The morphology, grain size and elemental distribution of the thin films were characterized by SEM and TEM. The crystallization and crystal phases were determined by XRD patterns, and the existence of graphene in Bi2WO6/graphene composite thin films were confirmed by Raman spectra. The photocatalytic performance of Bi2WO6 and Bi2WO6/graphene thin films was investigated by oxidizing NO under visible light irradiation. The results showed that Bi2WO6/graphene with 4 wt% of graphene showed the highest photocatalytic performance among all samples. This could be attributed to the increased electron conductivity with the presence of graphene. However, a further increased graphene concentration resulted in a decreased photocatalytic performance.

  9. Preparation and photoelectric properties of p-CaFe{sub 2}O{sub 4}/n-WO{sub 3} composites

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Ruiqin; Jia, Caihong [Key Laboratory of Photovoltaic Materials of Henan Province and School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Zhang, Weifeng, E-mail: wfzhang@henu.edu.cn [Key Laboratory of Photovoltaic Materials of Henan Province and School of Physics and Electronics, Henan University, Kaifeng 475004 (China)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Surface photovoltage spectroscopy investigation on p-CaFe{sub 2}O{sub 4}/n-WO{sub 3} composites. Black-Right-Pointing-Pointer The photovoltaic response is enhanced in p-CaFe{sub 2}O{sub 4}/n-WO{sub 3} composites. Black-Right-Pointing-Pointer The multielectron process and high rate of carrier migration in WO{sub 3}. - Abstract: Composites of p-CaFe{sub 2}O{sub 4}/n-WO{sub 3} are prepared via a sol-gel technique. Their structures and optical properties are characterized with X-ray diffraction, scanning electron microscopy and UV-vis absorption spectroscopy. The photoelectric characteristics are investigated by surface photovoltage spectroscopy combined with electric field induced surface photovoltage spectroscopy. The results indicate that CaFe{sub 2}O{sub 4} can well form a p-n type composite with WO{sub 3}, and the intensity and spectral region of surface photovoltaic response for the composites are strongly dependent on the molar ratio of two components. The enhancement in photoelectric properties and the effective separation of photogenerated carriers could be attributed to the energy level matching between the two components, multielectron process and the high migration rate in WO{sub 3}.

  10. Synthesis of γ-WO{sub 3} thin films by hot wire-CVD and investigation of its humidity sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Jadkar, Vijaya; Waykar, Ravindra; Jadhavar, Ashok [School of Energy Studies, Savitribai Phule Pune University, Pune 411 007 (India); Pawbake, Amit [School of Energy Studies, Savitribai Phule Pune University, Pune 411 007 (India); Physical and Material Chemistry Division, National Chemical Laboratory, Pune 411 008 (India); Date, Abhijit [School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Plenty Road, Bundoora, Melbourne VIC 3083 (Australia); Late, Dattatray [Physical and Material Chemistry Division, National Chemical Laboratory, Pune 411 008 (India); Pathan, Habib; Gosavi, Suresh; Jadkar, Sandesh [Department of Physics, Savitribai Phule Pune University, Pune 411 007 (India)

    2017-05-15

    In this study, monoclinic tungsten oxide (γ-WO{sub 3}) have been grown in a single step using HW-CVD method by resistively heating W filaments in a constant O{sub 2} pressure. The formation of γ-WO{sub 3} was confirmed using low angle-XRD and Raman spectroscopy analysis. Low angle-XRD analysis revealed that as-deposited WO{sub 3} film are highly crystalline and the crystallites have preferred orientation along the (002) direction. HRTEM analysis and SAED pattern also show the highly crystalline nature of WO{sub 3} with d spacing of ∝ 0.38 nm, having an orientation along the (002) direction. Surface topography investigated by SEM analysis shows the formation of a uniform and homogeneous cauliflower like morphology throughout the substrate surface without flaws and cracks. A humidity sensing device incorporating WO{sub 3} is also fabricated, which shows a maximum humidity sensitivity factor of ∝ 3954% along with a response time of ∝14 s and a recovery time of ∝25 s. The obtained results demonstrate that it is possible to synthesize WO{sub 3} in a single step by HW-CVD method and to fabricate a humidity sensor by using it. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Cross-cultural adaptation of the Work Disability Diagnosis Interview (WoDDI for the Brazilian context Adaptación transcultural del Work Disability Diagnosis Interview (WoDDI para el contexto brasileño Adaptação transcultural do Work Disability Diagnosis Interview (WoDDI para o contexto brasileiro

    Directory of Open Access Journals (Sweden)

    Vivian Aline Mininel

    2012-02-01

    Full Text Available The Work Disability Diagnosis Interview (WoDDI is a structured interview guide developed by the University of Sherbrooke, Canada to help clinicians detect the most important work-related disability predictors and to identify one or more causes of prolonged absenteeism. This methodological study aims for the cross-cultural adaptation of the WoDDI for the Brazilian context. The method followed international guidelines for studies of this kind, including the following steps: initial translation, synthesis of translations, back translation, evaluation by an expert committee and testing of the penultimate version. These steps allowed obtaining conceptual, semantic, idiomatic, experiential and operational equivalences, in addition to content validity. The results showed that the translated WoDDI is adapted to the Brazilian context and can be used after training.El Work Disability Diagnosis Interview (WoDDI es una guía de entrevista estructurada desarrollada por la Universidad de Sherbrooke (Canadá, para ayudar a los profesionales de la salud a detectar los predictores de mayor importancia para personas con trastornos relacionados con el trabajo y para identificar una o más causas de ausentismo prolongado del trabajo. Este estudio metodológico se dirige a la adaptación transcultural (WoDDI para el contexto brasileño. El método siguió las recomendaciones internacionales para este tipo de estudio, el que comprende las siguientes etapas: traducción inicial, síntesis de las traducciones, retraducción, revisión del comité de expertos y prueba de la versión pre-final. Estas medidas permitieron obtener la equivalencia conceptual, semántica, idiomática y la experiencia operacional, además de la validación del contenido. Los resultados mostraron que el WoDDI traducido se adapta a la realidad brasileña e puede ser utilizado, después de la capacitación previa.O Work Disability Diagnosis Interview (WoDDI é um guia de entrevista estruturada

  12. Investigation of the La2O3-Nb2O5-WO3 ternary phase diagram: Isolation and crystal structure determination of the original La3NbWO10 material

    KAUST Repository

    Vu, T.D.

    2015-05-23

    In the course of the exploration of the La2O3-WO3-Nb2O5 ternary phase diagram, a new compound with the formula La3NbWO10 was discovered. Its structure was determined from a combination of powder X-ray and neutron diffraction data. It crystallizes in the tetragonal space group P42/nmc (no. 137) with the lattice parameters: a=10.0807(1) Å; c=12.5540(1) Å. The structure is built up from infinite ribbons of octahedra (W/Nb)O5 which are perpendicular to each other, lanthanum ions being distributed around these ribbons. The electrical properties of this compound were investigated on sintered pellets by means of complex impedance spectroscopy. © 2015 Elsevier Inc. All rights reserved.

  13. Sliding charge density wave in the monophosphate tungsten bronze (PO2)4(WO3)2m with alternate stacking of m=4 and m=6 WO3 layers

    International Nuclear Information System (INIS)

    Foury-Leylekian, P.; Sandre, E.; Ravy, S.; Pouget, J.-P.; Elkaim, E.; Roussel, P.; Groult, D.; Labbe, Ph.

    2002-01-01

    The monophosphate tungsten bronzes (PO 2 ) 4 (WO 3 ) 2m form family of two-dimensional metals which exhibit charge density wave (CDW) instabilities. These materials are generally built by the regular stacking of (a,b) layers in which chains made of segments of m WO 6 octahedra directed along the a and a±b directions are delimited. Their electronic structure thus originates from quasi-one-dimensional (1D) bands located on these chains. As a consequence their Fermi surface (FS) exhibits large flat portions whose nesting gives rise to successive CDW instabilities. Here we present a structural study of the CDW instability of the (PO 2 ) 4 (WO 3 ) 10 member formed by the alternate stacking of layers built with segments of m=4 and m=6 WO 6 octahedra. Its ab initio electronic structure calculation shows that the FS of this member exhibits large flat portions which can be extremely well nested. Its best nesting wave vector accounts for the modulation wave vector stabilized by the CDW transition which occurs at 156 K. Because of the regular stacking of layers of different m values the FS is slightly split. The unusual thermal dependence of the x-ray satellite intensity provides evidence that the two types of layers become modulated at different temperature. This also leads to a slight thermal sliding of the CDW-nesting modulation wave vector, which can be accounted for within the framework of a Landau-Ginzburg theory. In addition, the observation of a global hysteresis in the thermal cycling of the satellite intensity, as well as the degradation of the interlayer order upon cooling, suggest the formation of a disordered lattice of dilute solitons. Such solitons allow to accommodate the charge transferred between the two types of layer. Finally the relevance of local charge transfers, at intergrowth defects, for example, to create pinned discommensurations that break the CDW coherence is emphasized in this whole family of bronzes

  14. Effect of direct current density on microstructure of tungsten coating electroplated from Na{sub 2}WO{sub 4}-WO{sub 3}-NaPO{sub 3} system

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Fan, E-mail: jiangfan1109@163.com; Zhang, Yingchun, E-mail: zycustb@163.com; Sun, Ningbo, E-mail: suningbo682@163.com; Liu, Zhi’ang, E-mail: zhiang_001@163.com

    2014-10-30

    Highlights: • Tungsten coatings were electroplated from the Na{sub 2}WO{sub 4}-WO{sub 3}-NaPO{sub 3} melt. • Tungsten coating comprised a tooth-like layer and a columnar growth layer. • The average grain size increases as increasing current density. • (2 1 1) Orientation is favored most likely for samples obtained at various durations. • The growth rate of tungsten crystal nucleus is higher than the nucleation rate. - Abstract: Pure tungsten coating with body-centered cubic (bbc) structure was successfully electrodeposited from Na{sub 2}WO{sub 4}-WO{sub 3}-NaPO{sub 3} molten salt at 1153 K in atmosphere. The coatings comprised an inner layer of tooth-like grains and an outer layer of columnar grains with a thin diffusion layer of tungsten in the Cu substrate. The effects of current density and electrodeposition duration on the morphology and microstructure of the coatings were investigated in this paper. With increasing of current density from 50 to 80 mA cm{sup −2}, the grain size of the tungsten coating increased from 7.01 μm to 12.44 μm. With the increase of the current density, the thickness of the coating changed from 25.92 μm to 34.40 μm, and then dropped to 29.72 μm. The preferred orientation of the coatings changed from (2 2 0) to (2 1 1). With the increasing of duration, the grain size and thickness of tungsten coatings increased while the (2 1 1) favored orientation dot not changed. Because of the low current efficiency at long duration of direct current electrodeposition, it should not be suitable for the electroplating of thick tungsten coating.

  15. On tungstates of divalent cations (I). Structural investigation and spectroscopic properties of Sr{sub 2}[WO{sub 5}] and Ba{sub 2}[WO{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Jantz, Stephan G.; Dialer, Marwin; Hoeppe, Henning A. [Lehrstuhl fuer Festkoerperchemie, Universitaet Augsburg (Germany); Pielnhofer, Florian [Abteilung Nanochemie, Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany)

    2017-12-13

    The crystal structures of Sr{sub 2}[WO{sub 5}] [Pna2{sub 1}, a = 7.2457(3) Aa, b = 10.8867(5) Aa, c = 5.5391(3) Aa, Z = 4, R{sub int} = 0.0671, R{sub 1} = 0.0495, wR{sub 2} = 0.0462] and Ba{sub 2}[WO{sub 5}] [Pnma, a = 7.3828(2) Aa, b = 5.71420(10) Aa, c = 11.4701(3) Aa, Z = 4, R{sub int} = 0.0294, R{sub 1} = 0.0146, wR{sub 2} = 0.0284] are revised, based on single-crystal XRD data. Furthermore spectroscopic data (infrared, Raman, and UV/Vis) assisted by DFT calculations are discussed and first results on the luminescence properties of Sr{sub 2}[WO{sub 5}]:Eu{sup 3+} are presented. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Prospects for a precision timing upgrade of the CMS PbWO crystal electromagnetic calorimeter for the HL-LHC

    CERN Document Server

    Massironi, Andrea

    2017-01-01

    The upgrade of the Compact Muon Solenoid (CMS) crystal electromagnetic calorimeter (ECAL), which will operate at the High Luminosity Large Hadron Collider (HL-LHC), will achieve a timing resolution of around 30 ps for high energy photons and electrons. In this talk we will discuss the benefits of precision timing for the ECAL event reconstruction at HL-LHC. Simulation studies focused on the timing properties of PbWO$_4$ crystals, as well as the impact of the photosensors and the readout electronics on the timing performance, will be presented. Test beam studies intended to measure the timing performance of the PbWO$_4$ crystals with different photosensors and readout electronics will be shown.

  17. Prospects for a precision timing upgrade of the CMS PbWO crystal electromagnetic calorimeter for the HL-LHC

    Science.gov (United States)

    Massironi, A.

    2018-04-01

    The upgrade of the Compact Muon Solenoid (CMS) crystal electromagnetic calorimeter (ECAL), which will operate at the High Luminosity Large Hadron Collider (HL-LHC), will achieve a timing resolution of around 30 ps for high energy photons and electrons. In this talk we will discuss the benefits of precision timing for the ECAL event reconstruction at HL-LHC. Simulation studies focused on the timing properties of PbWO4 crystals, as well as the impact of the photosensors and the readout electronics on the timing performance, will be presented. Test beam studies intended to measure the timing performance of the PbWO4 crystals with different photosensors and readout electronics will be shown.

  18. End-pumped continuous-wave intracavity yellow Raman laser at 590 nm with SrWO4 Raman crystal

    Science.gov (United States)

    Yang, F. G.; You, Z. Y.; Zhu, Z. J.; Wang, Y.; Li, J. F.; Tu, C. Y.

    2010-01-01

    We present an end-pumped continuous-wave intra-cavity yellow Raman laser at 590 nm with a 60 mm long pure crystal SrWO4 and an intra-cavity LiB3O5 frequency doubling crystal. The highest output power of yellow laser at 590 nm was 230 mW and the output power and threshold were found to be correlative with the polarized directions of pure single crystal SrWO4 deeply. Along different directions, the minimum and maximum thresholds of yellow Raman laser at 590 nm were measured to be 2.8 W and 14.3 W with respect to 808 nm LD pump power, respectively.

  19. End-pumped continuous-wave intracavity yellow Raman laser at 590 nm with SrWO4 Raman crystal

    International Nuclear Information System (INIS)

    Yang, F G; You, Z Y; Zhu, Z J; Wang, Y; Li, J F; Tu, C Y

    2010-01-01

    We present an end-pumped continuous-wave intra-cavity yellow Raman laser at 590 nm with a 60 mm long pure crystal SrWO 4 and an intra-cavity LiB 3 O 5 frequency doubling crystal. The highest output power of yellow laser at 590 nm was 230 mW and the output power and threshold were found to be correlative with the polarized directions of pure single crystal SrWO 4 deeply. Along different directions, the minimum and maximum thresholds of yellow Raman laser at 590 nm were measured to be 2.8 W and 14.3 W with respect to 808 nm LD pump power, respectively

  20. An economic analysis of the deposition of electrochromic WO3 via sputtering or plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Garg, D.; Henderson, P.B.; Hollingsworth, R.E.; Jensen, D.G.

    2005-01-01

    The costs of manufacturing electrochromic WO 3 thin films deposited by either radio frequency plasma enhanced chemical vapor deposition (PECVD) or DC reactive magnetron sputtering of metal targets were modeled. Both inline systems for large area glass substrates and roll-to-roll systems for flexible webs were compared. Costs of capital, depreciation, raw materials, labor, power, and other miscellaneous items were accounted for in the model. The results predict that on similar sized systems, PECVD can produce electrochromic WO 3 for as little as one-third the cost, and have more than 10 times the annual production capacity of sputtering. While PECVD cost is dominated by raw materials, primarily WF 6 , sputtering cost is dominated by labor and depreciation

  1. An economic analysis of the deposition of electrochromic WO{sub 3} via sputtering or plasma enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Garg, D. [Air Products and Chemicals Inc., 7201 Hamilton Blvd., Allentown, PA 18195-7201 (United States); Henderson, P.B. [Air Products and Chemicals Inc., 7201 Hamilton Blvd., Allentown, PA 18195-7201 (United States)]. E-mail: henderpb@airproducts.co; Hollingsworth, R.E. [ITN Energy Systems Inc., 8130 Shaffer Pkwy, Littleton, CO 80127 (United States); Jensen, D.G. [ITN Energy Systems Inc., 8130 Shaffer Pkwy, Littleton, CO 80127 (United States)

    2005-06-15

    The costs of manufacturing electrochromic WO{sub 3} thin films deposited by either radio frequency plasma enhanced chemical vapor deposition (PECVD) or DC reactive magnetron sputtering of metal targets were modeled. Both inline systems for large area glass substrates and roll-to-roll systems for flexible webs were compared. Costs of capital, depreciation, raw materials, labor, power, and other miscellaneous items were accounted for in the model. The results predict that on similar sized systems, PECVD can produce electrochromic WO{sub 3} for as little as one-third the cost, and have more than 10 times the annual production capacity of sputtering. While PECVD cost is dominated by raw materials, primarily WF{sub 6}, sputtering cost is dominated by labor and depreciation.

  2. Possible nucleation of a 2D superconducting phase on WO3 single crystals surface doped with Na+

    International Nuclear Information System (INIS)

    Reich, S.; Tsabba, Y.

    1999-01-01

    WO 3 crystals with a surface composition of Na 0.05 WO 3 were grown. These crystals exhibit a sharp diamagnetic step in magnetization at 91 K, and a magnetic hysteresis below this temperature. As the temperature is lowered below 100 K in transport measurements, a sharp metal to insulator transition is observed, this is followed by a sharp decrease in the resistivity when the temperature is lowered to about 90 K. When the surface of the crystals was covered by gold the depth of the diamagnetic step had decreased considerably. These results indicate a possible nucleation of a superconducting phase on the surface of these crystals. This is a non cuprate system exhibiting a critical temperature in the HTS range. (orig.)

  3. Nanospherical composite of WO{sub 3} wrapped NaTaO{sub 3}: Improved photodegradation of tetracycline under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Lingnan; Lang, Junyu; Wang, Shuwei; Chai, Zhanli; Su, Yiguo; Wang, Xiaojing, E-mail: wang_xiao_jing@hotmail.com

    2016-12-01

    Graphical abstract: - Highlights: • A novel ternary NaTaO{sub 3}@WO{sub 3} photocatalyst was successfully fabricated. • NaTaO{sub 3}@WO{sub 3} composites exhibited spherical assemblies with fine WO{sub 3} nanosheets wrapped on the cube NaTaO{sub 3} nanoparticles. • NaTaO{sub 3}@WO{sub 3} showed the enhanced photocatalytic performance in the tetracycline hydrochloride degradation under visible light irradiation. • An adsorption−degradation photocatalytic mechanism promoted through a Z-type heterojunction was proposed. - Abstract: In this paper, WO{sub 3}-wrapped NaTaO{sub 3} nanospheres photocatalysts with different W/Ta molar ratios were successfully prepared via a facile hydrothermal method. The samples were characterized by X-ray diffraction, transmission and scan electron microscopy, X-ray photoelectron spectroscopy, FT-IR spectrum, UV−vis diffuse reflectance spectroscopy, and Barrett−Emmett−Teller technique. The photocatalytic activities for degrading tetracycline hydrochloride under visible light irradiation were examined. The results indicated that the as-prepared NaTaO{sub 3}@WO{sub 3} photocatalysts showed the obvious enhancement in the tetracycline hydrochloride degradation ratio, compared with the pure NaTaO{sub 3} and WO{sub 3} under visible light irradiation. The optimum percentage of NaTaO{sub 3}@WO{sub 3} composites with a 60.88% degradation rate was W:Ta = 0.3:1 in mole, which was mainly attributed to the effective separation of the photo-generated electron and hole as well as the expanding of the absorption edge to the visible region due to the spherical heterojunction by wrapping WO{sub 3} on the surface of NaTaO{sub 3}. The radicals trapping experiments demonstrated that there were multiple active species during the degrading process of TC. The possible mechanism of tetracycline hydrochloride degradation by NaTaO{sub 3}@WO{sub 3} composite was also proposed.

  4. Photocatalytic reduction of CO{sub 2} into methanol and ethanol over conducting polymers modified Bi{sub 2}WO{sub 6} microspheres under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Weili, E-mail: wldai81@126.com; Xu, Hai; Yu, Juanjuan; Hu, Xu; Luo, Xubiao, E-mail: luoxubiao@126.com; Tu, Xinman; Yang, Lixia

    2015-11-30

    Graphical abstract: - Highlights: • Conducting polymers modified Bi{sub 2}WO{sub 6} HHMS (CP/Bi{sub 2}WO{sub 6}) was successfully synthesized. • The introduction of CP decreases the recombination of photogenerated e{sup –}–h{sup +} pairs. • The PTh/Bi{sub 2}WO{sub 6} exhibites good stability and recyclability for CO{sub 2} photoreduction. • The possible photocatalytic mechanism was discussed and proposed. - Abstract: Bi{sub 2}WO{sub 6} hierarchical hollow microspheres (HHMS) modified with different conducting polymers (polyaniline, polypyrrole, and polythiophene) were successfully synthesized by ‘in situ’ deposition oxidative polymerization method, and evaluated as photocatalysts for the photocatalytic reduction of CO{sub 2} with H{sub 2}O to methanol and ethanol. It was found that the introduction of conducting polymers obviously decreased the recombination of photogenerated electron–hole pairs, thus promoting the photocatalytic activity of Bi{sub 2}WO{sub 6}. Among the as-fabricated photocatalysts, polythiophene modified Bi{sub 2}WO{sub 6} (PTh/Bi{sub 2}WO{sub 6}) exhibited the best photoelectronic and photocatalytic performance, due to the narrow band gap and good charge mobility of polythiophene. The results demonstrate that the methanol and ethanol yield over PTh/Bi{sub 2}WO{sub 6} was 56.5 and 20.5 μmol g{sub cat}{sup −1} in 4 h, respectively. The total yield of hydrocarbons is 2.8 times higher than that over pure Bi{sub 2}WO{sub 6}. It is noted that the catalyst exhibits good recyclability and stability. After five consecutive runs, the PTh/Bi{sub 2}WO{sub 6} catalyst shows no significant loss of photocatalytic activity. The possible photocatalytic mechanism was proposed which is beneficial for further improving the activity of photocatalysts. The approach described in this study provides a simple and reliable strategy for the rational design of efficient visible light-driven photocatalysts for photoreduction of CO{sub 2} to hydrocarbons.

  5. Luminescence and photo-thermally stimulated defects creation processes in PbWO{sub 4} crystals doped with trivalent rare-earth ions

    Energy Technology Data Exchange (ETDEWEB)

    Fabeni, P. [Institute of Applied Physics “N.Carrara” (IFAC) of CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Firenze) (Italy); Krasnikov, A.; Kärner, T. [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia); Laguta, V.V.; Nikl, M. [Institute of Physics AS CR, Cukrovarnicka 10, 16253 Prague (Czech Republic); Pazzi, G.P. [Institute of Applied Physics “N.Carrara” (IFAC) of CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Firenze) (Italy); Zazubovich, S., E-mail: svet@fi.tartu.ee [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia)

    2013-04-15

    In PbWO{sub 4} crystals, doped with various trivalent rare-earth A{sup 3+} ions (A{sup 3+}: La{sup 3+}, Lu{sup 3+}, Y{sup 3+}, Ce{sup 3+}, Gd{sup 3+}), electron (WO{sub 4}){sup 3−} and {(WO_4)"3"−–A"3"+} centers can be created under UV irradiation not only in the host absorption region but also in the energy range around 3.85 eV (Böhm et al., 1999; Krasnikov et al., 2010). Under excitation in the same energy range, the UV emission peak at 3.05–3.20 eV is observed. In the present work, the origin of this emission is investigated in detail by low-temperature time-resolved luminescence methods. Photo-thermally stimulated creation of (WO{sub 4}){sup 3−} and {(WO_4)"3"−–A"3"+} centers is studied also in PbWO{sub 4}:Mo,A{sup 3+} crystals. Various processes, which could explain both the appearance of the UV emission and the creation of the {(WO_4)"3"−–A"3"+}-type centers under irradiation of PbWO{sub 4}: A{sup 3+} crystals in the 3.85±0.35 eV energy range, are discussed. The radiative and non-radiative decay of the excitons localized near A{sup 3+} ions is considered as the most probable mechanism to explain the observed features. -- Highlights: ► UV emission of PbWO{sub 4}: A{sup 3+} (A{sup 3+}: La{sup 3+}, Lu{sup 3+}, Y{sup 3+}, Ce{sup 3+}, and Gd{sup 3+}) crystals is studied. ► The emission is ascribed to the radiative decay of excitons localized near A{sup 3+} ions. ► The excitons are created at 3.85 eV excitation by a two-step process. ► Non-radiative decay of the excitons leads to the creation of (WO{sub 4}){sup 3−}–A{sup 3+} centers.

  6. Enhanced photocatalytic degradation of norfloxacin in aqueous Bi2WO6 dispersions containing nonionic surfactant under visible light irradiation

    International Nuclear Information System (INIS)

    Tang, Lin; Wang, Jiajia; Zeng, Guangming; Liu, Yani; Deng, Yaocheng; Zhou, Yaoyu; Tang, Jing; Wang, Jingjing; Guo, Zhi

    2016-01-01

    Highlights: • TX100 strongly enhanced the adsorption and photodegradation of NOF in Bi 2 WO 6 dispersions under visible light irradiation (400–750 nm). • Cu 2+ (10 mM) significantly suppressed the photocatalytic degradation of NOF. • FT-IR demonstrated that the NOF adsorbed on Bi 2 WO 6 was completely degraded. • Three possible photocatalytic degradation pathways of NOF were proposed, according to the HPLC/MS/MS analysis. - Abstract: Photocatalytic degradation is an alternative method to remove pharmaceutical compounds in water, however it is hard to achieve efficient rate because of the poor solubility of pharmaceutical compounds in water. This study investigated the photodegradation of norfloxacin in a nonionic surfactant Triton-X100 (TX100)/Bi 2 WO 6 dispersion under visible light irradiation (400–750 nm). It was found that the degradation of poorly soluble NOF can be strongly enhanced with the addition of TX100. TX100 was adsorbed strongly on Bi 2 WO 6 surface and accelerated NOF photodegradation at the critical micelle concentration (CMC = 0.25 mM). Higher TX100 concentration (>0.25 mM) lowered the degradation rate. In the presence of TX100, the degradation rate reached the maximum value when the pH value was 8.06. FTIR analyses demonstrated that the adsorbed NOF on the catalyst was completely degraded after 2 h irradiation. According to the intermediates identified by HPLC/MS/MS, three possible degradation pathways were proposed to include addition of hydroxyl radical to quinolone ring, elimination of piperazynilic ring in fluoroquinolone molecules, and replacement of F atoms on the aromatic ring by hydroxyl radicals.

  7. Electrochemical investigation of electrochromic devices based on NiO and WO3 films using different lithium salts electrolytes

    International Nuclear Information System (INIS)

    Wei, Youxiu; Chen, Mu; Liu, Weiming; Li, Lei; Yan, Yue

    2017-01-01

    Highlights: •ECDs based on NiO and WO 3 films using different electrolytes were fabricated. •Effect of different electrolytes on films and ECDs was investigated. •Applied voltage distribution on NiO and WO 3 electrodes in an ECD was studied. •Voltage distribution on films was unbalanced and associated with electrolyte. •Films have different impedance behavior in different states and electrolytes. -- Abstract: Electrochromic devices (ECDs) with different liquid electrolytes were fabricated using NiO film as counter electrode, WO 3 film as working electrode. The effect of liquid electrolytes containing different lithium salts (LiClO 4 , LiPF 6 , LiTFSI) on films and ECDs was investigated, such as transmittance change, charge density, memory effect and cyclic stability. Films or ECDs using LiPF 6 electrolyte have excellent electrochromic properties but low cyclic stability, compared with LiClO 4 and LiTFSI electrolytes. In order to deeply understand the effect of electrolyte on films and devices, the voltage distribution of films based on an analog cell and electrochemical impedance spectroscopy (EIS) were measured and analyzed in different lithium salts electrolytes. Results show that voltage distribution and EIS characteristics of films have obvious difference in liquid LiClO 4 , LiPF 6 and LiTFSI electrolytes. Voltage distribution on NiO and WO 3 films is unbalanced and the impedance of films in bleached and colored states is different in the same electrolyte.

  8. Mn-Na{sub 2}WO{sub 4}/SiO{sub 2}. An industrial catalyst for methane coupling?

    Energy Technology Data Exchange (ETDEWEB)

    Yildiz, M.; Arndt, S.; Otremba, T.; Thomas, A.; Schomaeker, R. [Technische Univ. Berlin (Germany). Dept. of Chemistry; Simon, U.; Berthold, A.; Goerke, O.; Schubert, H. [Technische Univ. Berlin (Germany). Dept. of Materials Science; Aksu, Y. [Akdeniz Univ. (Turkey). Dept. of Material Science and Engineering

    2012-07-01

    The oxidative coupling of methane (OCM) is one of the best reactions for the direct conversion of methane. Despite all efforts, a suitable OCM process has not been put into practice yet, due to a lack of active, selective and stable catalyst. Mn-Na{sub 2}WO{sub 4}/SiO{sub 2} has attracted great interest because of its proven long term stability and its highly suitable catalytic performance. In spite of the large number of studies on this catalyst, structural characterizations are very difficult due to its complex trimetallic and multiphase nature. Previously, we studied a broad variety of support materials for the Mn-Na{sub 2}WO{sub 4}/SiO{sub 2} catalyst, e.g. Al{sub 2}O{sub 3}, TiO{sub 2}, ZrO{sub 2} and MgO. We found that SiO{sub 2} is the most suitable support material. A variation of the SiO{sub 2} materials showed that the catalytic performance does not differ substantially. However, the performance of SBA-15 supported Mn-Na{sub 2}WO{sub 4} catalyst was outstanding in comparison to all other silica supported catalysts. The reason of this substantial increase in the activity could be the ordered mesoporous structure of its support material. To understand the reaction mechanism, the kinetic isotope effect (KIE) with CD{sub 4} over Mn-Na{sub 2}WO{sub 4}/SiO{sub 2} was studied, we found that the consecutive oxidation of the C{sub 2} products is an important constraint as described in the literature for other catalysts. In order to apply this catalyst in a miniplant, we developed an upscaled preparation procedure via a fluidized bed granulation, allowing the preparation of large amounts of this catalyst. (orig.)

  9. Relevance of the NR4A sub-family of nuclear orphan receptors in trophoblastic BeWo cell differentiation.

    Science.gov (United States)

    Malhotra, Sudha Saryu; Gupta, Satish Kumar

    2017-01-01

    Nur-77, a member of the NR4A sub-family of nuclear orphan receptors, is downregulated in the placentae of pre-eclamptic women. Here, we investigate the relevance of Nor-1, Nurr-1 and Nur-77 in trophoblastic cell differentiation. Their transcript levels were found to be significantly upregulated in BeWo cells treated with forskolin. The maximum increase was observed after 2 h, with a second peak in the expression levels after 48 h. The expression of NR4A sub-family members was also found to be upregulated in BeWo cells after treatment with hCG and GnRH. A similar significant increase was observed at the respective protein levels after 2 and 48 h of treatment with forskolin, hCG or GnRH. Silencing Nor-1, Nurr-1 or Nur-77 individually did not show any effect on forskolin-, hCG- and/or GnRH-mediated BeWo cell fusion and/or hCG secretion. After silencing any one member of the NR4A sub-family, an increase in the transcript levels of the other sub-family members was observed, indicating a compensatory effect due to their functional redundancy. Simultaneously silencing all three NR4A sub-family members significantly downregulated forskolin- and hCG-mediated BeWo cell fusion and/or hCG secretion. However, a considerable amount of cell death occurred after forskolin or hCG treatment as compared to the control siRNA-transfected cells. These results suggest that the NR4A sub-family of nuclear orphan receptors has a role in trophoblastic cell differentiation.

  10. Novel tree-like WO3 nanoplatelets with very high surface area synthesized by anodization under controlled hydrodynamic conditions

    OpenAIRE

    Fernández Domene, Ramón Manuel; Sánchez Tovar, Rita; SEGURA SANCHIS, ELENA; Garcia-Anton, Jose

    2016-01-01

    In the present work, a new WO3 nanostructure has been obtained by anodization in a H2SO4/NaF electrolyte under controlled hydrodynamic conditions using a Rotating Disk Electrode (RDE) configuration. Anodized samples were analyzed by means of Field Emission Scanning Electronic Microscopy (FESEM), Confocal Raman Microscopy and photoelectrochemical measurements. The new nanostructure, which consists of nanoplatelets clusters growing in a tree-like manner, presents a very high surface area expose...

  11. Effect of Sensors on the Reliability and Control Performance of Power Circuits in the Web of Things (WoT

    Directory of Open Access Journals (Sweden)

    Sungwoo Bae

    2016-09-01

    Full Text Available In order to realize a true WoT environment, a reliable power circuit is required to ensure interconnections among a range of WoT devices. This paper presents research on sensors and their effects on the reliability and response characteristics of power circuits in WoT devices. The presented research can be used in various power circuit applications, such as energy harvesting interfaces, photovoltaic systems, and battery management systems for the WoT devices. As power circuits rely on the feedback from voltage/current sensors, the system performance is likely to be affected by the sensor failure rates, sensor dynamic characteristics, and their interface circuits. This study investigated how the operational availability of the power circuits is affected by the sensor failure rates by performing a quantitative reliability analysis. In the analysis process, this paper also includes the effects of various reconstruction and estimation techniques used in power processing circuits (e.g., energy harvesting circuits and photovoltaic systems. This paper also reports how the transient control performance of power circuits is affected by sensor interface circuits. With the frequency domain stability analysis and circuit simulation, it was verified that the interface circuit dynamics may affect the transient response characteristics of power circuits. The verification results in this paper showed that the reliability and control performance of the power circuits can be affected by the sensor types, fault tolerant approaches against sensor failures, and the response characteristics of the sensor interfaces. The analysis results were also verified by experiments using a power circuit prototype.

  12. Two stacked tandem white organic light-emitting diodes employing WO3 as a charge generation layer

    Science.gov (United States)

    Bin, Jong-Kwan; Lee, Na Yeon; Lee, SeungJae; Seo, Bomin; Yang, JoongHwan; Kim, Jinook; Yoon, Soo Young; Kang, InByeong

    2016-09-01

    Recently, many studies have been conducted to improve the electroluminescence (EL) performance of organic lightemitting diodes (OLEDs) by using appropriate organic or inorganic materials as charge generation layer (CGL) for their application such as full color displays, backlight units, and general lighting source. In a stacked tandem white organic light-emitting diodes (WOLEDs), a few emitting units are electrically interconnected by a CGL, which plays the role of generating charge carriers, and then facilitate the injection of it into adjacent emitting units. In the present study, twostacked WOLEDs were fabricated by using tungsten oxide (WO3) as inorganic charge generation layer and 1,4,5,8,9,11- hexaazatriphenylene hexacarbonitrile (HAT-CN) as organic charge generation layer (P-CGL). Organic P-CGL materials were used due to their ease of use in OLED fabrication as compared to their inorganic counterparts. To obtain high efficiency, we demonstrate two-stacked tandem WOLEDs as follows: ITO/HIL/HTL/HTL'/B-EML/ETL/N-CGL/P-CGL (WO3 or HAT-CN)/HTL″/YG-EML/ETL/LiF/Al. The tandem devices with blue- and yellow-green emitting layers were sensitive to the thickness of an adjacent layer, hole transporting layer for the YG emitting layer. The WOLEDs containing the WO3 as charge generation layer reach a higher power efficiency of 19.1 lm/W and the current efficiency of 51.2 cd/A with the white color coordinate of (0.316, 0.318) than the power efficiency of 13.9 lm/W, and the current efficiency of 43.7 cd/A for organic CGL, HAT-CN at 10 mA/cm2, respectively. This performance with inserting WO3 as CGL exhibited the highest performance with excellent CIE color coordinates in the two-stacked tandem OLEDs.

  13. Bingham viscosity and yield stress of molten (TeO2)0.78(WO3)0.22 glass

    International Nuclear Information System (INIS)

    Churbanov, M.F.; Snopatin, G.E.; Shaposhnikov, R.M.; Shabarov, V.V.; Plotnichenko, V.G.

    2007-01-01

    The flow of molten (TeO 2 ) 0.78 (WO 3 ) 0.22 glass in a circular-cylindrical channel has been studied at temperatures from 390 to 430 deg C. The variation of the measured volumetric flow rate with the gas pressure over the melt attests to non-Newtonian flow behavior. The flow rates calculated in the pseudo plastic model were used to determine the yield stress and plastic (Bingham) viscosity of the melt [ru

  14. Ultrathin Bi2WO6 nanosheet decorated with Pt nanoparticles for efficient formaldehyde removal at room temperature

    Science.gov (United States)

    Sun, Dong; Le, Yao; Jiang, Chuanjia; Cheng, Bei

    2018-05-01

    Two-dimensional (2D) ultrathin bismuth tungstate (Bi2WO6) nanosheets (BWO-NS) with a thickness of approximately 4.0 nm were synthesized by a one-step hydrothermal method, and decorated with platinum (Pt) nanoparticles (NPs) via an impregnation/borohydride-reduction approach. The as-prepared ultrathin Pt-BWO-NS exhibited superior catalytic activity for removing gaseous formaldehyde (HCHO) at ambient temperature, in comparison with bulk counterpart with Bi2WO6 sheet thickness of tens of nanometers. The ultrathin structure endowed the Pt-BWO-NS sample with larger specific surface area, which can provide abundant surface active sites for HCHO adsorption and facilitate the homogeneous dispersion of Pt NPs. X-ray photoelectron spectroscopy and hydrogen temperature-programmed reduction analyses revealed the interaction between the Bi2WO6 support and Pt species, which is crucial for activating surface oxygen atoms to participate in the catalytic HCHO oxidation process. By conducting in situ diffuse reflectance infrared Fourier transform spectroscopy under different atmospheres, i.e., gaseous HCHO in nitrogen or oxygen (O2), the reaction mechanism and the role of O2 were elucidated, with dioxymethylene, formate and linearly adsorbed carbon monoxide identified as the main reaction intermediates. This study may provide new enlightenment on fabricating novel 2D nanomaterials for efficient indoor air purification and potentially other environmental applications.

  15. The ITO-capped WO3 nanowires biosensor based on field-effect transistor in label-free protein sensing

    International Nuclear Information System (INIS)

    Shariati, Mohsen

    2017-01-01

    The fabrication of ITO-capped WO 3 nanowires associated with their bio-sensing properties in field-effect transistor diagnostics basis as a biosensor has been reported. The bio-sensing property for manipulated nanowires elucidated that the grown nanostructures were very sensitive to protein. The ITO-capped WO 3 nanowires biosensor showed an intensive bio-sensing activity against reliable protein. Polylysine strongly charged bio-molecule was applied as model system to demonstrate the implementation of materialized biosensor. The employed sensing mechanism was 'label-free' and depended on bio-molecule's intrinsic charge. For nanowires synthesis, the vapor-liquid-solid mechanism was used. Nanowires were beyond a few hundred nanometers in lengths and around 15-20 nm in diameter, while the globe cap's size on the nanowires was around 15-25 nm. The indium tin oxide (ITO) played as catalyst in nanofabrication for WO 3 nanowires growth and had outstanding role in bio-sensing especially for bio-molecule adherence. In applied electric field presence, the fabricated device showed the great potential to enhance medical diagnostics. (orig.)

  16. Radiopurity of CaWO{sub 4} crystals for direct dark matter search with CRESST and EURECA

    Energy Technology Data Exchange (ETDEWEB)

    Muenster, Andrea [Physik Department E15, Technische Universitaet Muenchen, 85748 Garching (Germany); Collaboration: CRESST-Collaboration

    2015-07-01

    The direct dark matter search experiment CRESST uses scintillating CaWO{sub 4} single crystals as targets for possible WIMP recoils. A particle interaction in the crystal produces phonons as well as scintillation light. As the light signal is dependent on the kind of interacting particle, e{sup -}-recoils and α-decays mainly originating from intrinsic impurities of the crystal can be discriminated from nuclear recoils (e.g. due to possible WIMP scatterings). To achieve the best possible discrimination a high light output and a high radiopurity of the crystals are crucial. Since 2011 CaWO{sub 4} crystals are grown in the crystal lab of TU Munich. In this way we can directly influence the growth parameters and find a method to improve light output and radiopurity which is required by CRESST and the future tonne-scale multi-material experiment EURECA. In this talk we will discuss the investigated radiopurity of the raw materials WO{sub 3} and CaCO{sub 3} as well as of TUM-grown crystals which are currently taking data in CRESST II Phase 2.

  17. Gasochromic performance of WO{sub 3}-nanorod thin films fabricated with an ArF excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Yaacob, M. H. [RMIT University, Melbourne (Australia); Universiti Putra Malaysia, Selangor (Malaysia); Ou, J. Z.; Wlodarski, W. [RMIT University, Melbourne (Australia); Kim, C. S.; Lee, J. Y. [KAIST, Daejon (Korea, Republic of); Kim, Y. H. [KIST, Seoul (Korea, Republic of); Oh, C. M.; Dhakal, K. P.; Kim, J. Y.; Kang, J. H. [University of Incheon, Incheon (Korea, Republic of)

    2012-02-15

    Thin films with tungsten trioxide (WO{sub 3}) nanorods were fabricated by using an ArF pulsed laser deposition system. Because the ArF excimer laser operates at a very short wavelength of 193 nm, short enough to expect strong absorption of the photons in the semiconductor oxide targets, and because the clusters incoming to the substrates have high momentum, we could build thin films with good surface morphology. Highly homogeneous arrays of nanorods with sizes mostly in the range of 30 - 40 nm were observed. The absorbance response towards hydrogen (H{sub 2}) gas was investigated for a WO{sub 3} film coated with 25-A-thick palladium (Pd). The Pd/WO{sub 3}-nanorod thin films exhibited excellent gasochromic response when measured in the visible-NIR range (400 - 1000 nm). As low as 0.06% H{sub 2} concentration was clearly sensed. A significant reversible absorbance change and fast recovery (<2 min) were observed when the films were exposed to H{sub 2} at different concentrations.

  18. Web-of-Objects (WoO)-based context aware emergency fire management systems for the Internet of Things.

    Science.gov (United States)

    Shamszaman, Zia Ush; Ara, Safina Showkat; Chong, Ilyoung; Jeong, Youn Kwae

    2014-02-13

    Recent advancements in the Internet of Things (IoT) and the Web of Things (WoT) accompany a smart life where real world objects, including sensing devices, are interconnected with each other. The Web representation of smart objects empowers innovative applications and services for various domains. To accelerate this approach, Web of Objects (WoO) focuses on the implementation aspects of bringing the assorted real world objects to the Web applications. In this paper; we propose an emergency fire management system in the WoO infrastructure. Consequently, we integrate the formation and management of Virtual Objects (ViO) which are derived from real world physical objects and are virtually connected with each other into the semantic ontology model. The charm of using the semantic ontology is that it allows information reusability, extensibility and interoperability, which enable ViOs to uphold orchestration, federation, collaboration and harmonization. Our system is context aware, as it receives contextual environmental information from distributed sensors and detects emergency situations. To handle a fire emergency, we present a decision support tool for the emergency fire management team. The previous fire incident log is the basis of the decision support system. A log repository collects all the emergency fire incident logs from ViOs and stores them in a repository.

  19. Web-of-Objects (WoO-Based Context Aware Emergency Fire Management Systems for the Internet of Things

    Directory of Open Access Journals (Sweden)

    Zia Ush Shamszaman

    2014-02-01

    Full Text Available Recent advancements in the Internet of Things (IoT and the Web of Things (WoT accompany a smart life where real world objects, including sensing devices, are interconnected with each other. The Web representation of smart objects empowers innovative applications and services for various domains. To accelerate this approach, Web of Objects (WoO focuses on the implementation aspects of bringing the assorted real world objects to the Web applications. In this paper; we propose an emergency fire management system in the WoO infrastructure. Consequently, we integrate the formation and management of Virtual Objects (ViO which are derived from real world physical objects and are virtually connected with each other into the semantic ontology model. The charm of using the semantic ontology is that it allows information reusability, extensibility and interoperability, which enable ViOs to uphold orchestration, federation, collaboration and harmonization. Our system is context aware, as it receives contextual environmental information from distributed sensors and detects emergency situations. To handle a fire emergency, we present a decision support tool for the emergency fire management team. The previous fire incident log is the basis of the decision support system. A log repository collects all the emergency fire incident logs from ViOs and stores them in a repository.

  20. Mieszkanie poetyckie – koncepcja twórczości Władysława Wołkowskiego

    Directory of Open Access Journals (Sweden)

    Anna Wywioł

    2015-05-01

    Full Text Available The concept of work by Wladyslaw Wołkowski is mainly based on the notion of poetic flat. He called for the nature to be used within the flat and the nature’s language to be transformed into its interior. The author’s anthropocentric attitude could be found in every, even the smallest project. The furniture and elements of decoration were supposed to serve the human in a best possible way, both because of its usefulness and its visual, symbolic and finally spiritual values. The piece of art, beside its beauty and usefulness, has to possess the elements of the era during which it was created and the author’s national identity expressed by history, literature, legends and fairy tales. The art, according to the poet, should aspire to unify the outer world with his inner state, assuming that it can influence such state. Wołkowski created modular materials in accordance with rhythmic and harmonic constructions. Harmonic merger of an individual with community – according to Wołkowski – is the guarantee of wellbeing and calmness of spirit.

  1. Constructing superhydrophobic WO3@TiO2 nanoflake surface beyond amorphous alloy against electrochemical corrosion on iron steel

    Science.gov (United States)

    Yu, S. Q.; Ling, Y. H.; Wang, R. G.; Zhang, J.; Qin, F.; Zhang, Z. J.

    2018-04-01

    To eliminate harmful localized corrosion, a new approach by constructing superhydrophobic WO3@TiO2 hierarchical nanoflake surface beyond FeW amorphous alloy formed on stainless steel was proposed. Facile dealloying and liquid deposition was employed at low temperature to form a nanostructured layer composing inner WO3 nanoflakes coated with TiO2 nanoparticles (NPs) layer. After further deposition of PFDS on nanoflakes, the contact angle reached 162° while the corrosion potential showed a negative shift of 230 mV under illumination, resulting in high corrosion resistance in 3.5 wt% NaCl solution. The tradeoff between superhydrophobic surface and photo-electro response was investigated. It was found that this surface feature makes 316 SS be immune to localized corrosion and a pronounced photo-induced process of electron storage/release as well as the stability of the functional layer were detected with or without illumination, and the mechanism behind this may be related to the increase of surface potential due to water repellence and the delayed cathodic protection of semiconducting coating derived mainly from the valence state changes of WO3. This study demonstrates a simple and low-cost electrochemical approach for protection of steel and novel means to produce superhydrophobic surface and cathodic protection with controllable electron storage/release on engineering scale.

  2. Web-of-Objects (WoO)-Based Context Aware Emergency Fire Management Systems for the Internet of Things

    Science.gov (United States)

    Shamszaman, Zia Ush; Ara, Safina Showkat; Chong, Ilyoung; Jeong, Youn Kwae

    2014-01-01

    Recent advancements in the Internet of Things (IoT) and the Web of Things (WoT) accompany a smart life where real world objects, including sensing devices, are interconnected with each other. The Web representation of smart objects empowers innovative applications and services for various domains. To accelerate this approach, Web of Objects (WoO) focuses on the implementation aspects of bringing the assorted real world objects to the Web applications. In this paper; we propose an emergency fire management system in the WoO infrastructure. Consequently, we integrate the formation and management of Virtual Objects (ViO) which are derived from real world physical objects and are virtually connected with each other into the semantic ontology model. The charm of using the semantic ontology is that it allows information reusability, extensibility and interoperability, which enable ViOs to uphold orchestration, federation, collaboration and harmonization. Our system is context aware, as it receives contextual environmental information from distributed sensors and detects emergency situations. To handle a fire emergency, we present a decision support tool for the emergency fire management team. The previous fire incident log is the basis of the decision support system. A log repository collects all the emergency fire incident logs from ViOs and stores them in a repository. PMID:24531299

  3. Structural and optical properties of crystalline and nanocrystalline NaIn(WO4)2:Cr3+

    International Nuclear Information System (INIS)

    Fuks, H.; Skibiński, T.; Kaczmarek, S.M.; Hanuza, J.; Leniec, G.; Hermanowicz, K.; Mączka, M.; Ptak, M.

    2014-01-01

    Highlights: • Optical properties are summarized for single crystals and nanopowders of NaIn(WO 4 ) 2 :Cr. • EPR properties are compared in terms of different site occupation of Cr ion in the NaIn(WO 4 ) 2 matrix. • The changes in the PL and ESR properties of the nanopowders vs. their decreasing size are studied. • An increase of isolated ions with temperature at the expense of chromium complexes is observed. • Magnetic susceptibility and moment of the powders are discussed in terms of Cr substitution. -- Abstract: EPR and optical spectra of chromium doped NaIn(WO 4 ) 2 single crystals and nanopowders have been measured. The resonance EPR measurements have been performed for two crystal orientations in respect to the magnetic field and analyzed in terms of various Cr 3+ ion site occupancies in the crystal lattice. They have been structurally and optically identified. The changes in the photoluminescence and electron spin resonance properties of the nanoparticles vs. their decreasing size have also been studied. Magnetic susceptibility and effective magnetic moment of the nanopowders were measured and discussed in terms of chromium substitution. Comparisons between chromium substitution in single crystals and nanopowders have been performed

  4. Optical temperature sensing by upconversion luminescence of Er doped Bi5TiNbWO15ferroelectric materials

    Directory of Open Access Journals (Sweden)

    Hua Zou

    2014-12-01

    Full Text Available The Er3+ doped Bi5TiNbWO15 ceramics have been synthesized using conventional solid-state reaction techniques. The crystal structure, ferroelectric properties, UC emission properties and especially the temperature sensing behaviors were systematically studied. With increasing Er3+ content, the investigation of XRD pattern, the ferroelectric loop and the UC emission indicated that the Er3+ ions dopants preferentially substituted the A sites of Bi3TiNbO9 and then Bi2WO6. Based on fluorescence intensity ratio (FIR technique, the observed results implied the ceramics were promising candidates for temperature sensors in the temperature range of 175 K −550 K. More importantly, this study provided a contrast of temperature sensitivity between emission from the same part (Bi3TiNbO9 in bismuth layered-structure and emission from the different part (Bi3TiNbO9 and Bi2WO6 in bismuth layered-structure for the first time.

  5. Investigation of Electrical, Optical and GaS Sensing properties Sol-Gel Derived WO3 Thin Films

    International Nuclear Information System (INIS)

    Dumludag, F.

    2008-01-01

    Tungsten oxide (WO 3 ) is a wide band gap n-type semiconductor. Thin films of WO 3 are considerable interest because of their potential applications in electrochromic devices, and gas sensors. In this work, WO 3 thin films were deposited on IDT (Interdigital electrodes) by a sol-gel dipping process. Precursor solution was prepared by dissolving of tungstic acid in ammonia. We investigated d.c. and a.c. (40 Hz-100 KHz) electrical properties of the films in the temperature range of 293K and 473K in vacuum ambient (10 - 2 mbar). We observed frequency dependent conductivity behavior at high frequencies. Absorption spectra of the film showed that a maximum absorption occurred at 330 nm. We also investigated the response of the films to vapors of the volatile organic compounds (acetone, chloroform, toluene, ethanol, ammonia) and water vapor. The films showed no sensitivity to the test gases at room temperature. Concentration of the vapors were controlled by mass flowmeters. All the measurement system was computerized

  6. Mesoporous WN/WO3-Composite Nanosheets for the Chemiresistive Detection of NO2 at Room Temperature

    Directory of Open Access Journals (Sweden)

    Fengdong Qu

    2016-07-01

    Full Text Available Composite materials, which can optimally use the advantages of different materials, have been studied extensively. Herein, hybrid tungsten nitride and oxide (WN/WO3 composites were prepared through a simple aqueous solution route followed by nitriding in NH3, for application as novel sensing materials. We found that the introduction of WN can improve the electrical properties of the composites, thus improving the gas sensing properties of the composites when compared with bare WO3. The highest sensing response was up to 21.3 for 100 ppb NO2 with a fast response time of ~50 s at room temperature, and the low detection limit was 1.28 ppb, which is far below the level that is immediately dangerous to life or health (IDLH values (NO2: 20 ppm defined by the U.S. National Institute for Occupational Safety and Health (NIOSH. In addition, the composites successfully lower the optimum temperature of WO3 from 300 °C to room temperature, and the composites-based sensor presents good long-term stability for NO2 of 100 ppb. Furthermore, a possible sensing mechanism is proposed.

  7. TiO{sub 2}/WO{sub 3} photoactive bilayers in the UV-Vis light region

    Energy Technology Data Exchange (ETDEWEB)

    Vasilaki, E. [University of Crete, Department of Chemistry, Heraklion, Crete (Greece); Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Vernardou, D. [Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Kenanakis, G.; Katsarakis, N. [Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, Vassilika Vouton, P.O. Box 1385, Heraklion, Crete (Greece); Vamvakaki, M. [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, Vassilika Vouton, P.O. Box 1385, Heraklion, Crete (Greece); University of Crete, Department of Materials Science and Technology, Heraklion, Crete (Greece)

    2017-04-15

    In this work, photoactive bilayered films consisting of anatase TiO{sub 2} and monoclinic WO{sub 3} were synthesized by a sol-gel route. Titanium isopropoxide and tungsten hexachloride were used as metal precursors and deposition was achieved by spin-coating on Corning glass substrates. The samples were characterized by X-ray diffraction, photoluminescence, UV-Vis, and Raman spectroscopy, as well as field emission scanning electron microscopy. The prepared immobilized catalysts were tested for their photocatalytic performance by the decolorization of methylene blue in aqueous matrices, under UV-Vis light irradiation. The annealing process influenced the crystallinity of the bilayered films, while the concentration of the tungsten precursor solution and the position of the tungsten trioxide layer further affected their photocatalytic performance. In particular, the photocatalytic performance of the bilayered films was optimized at a concentration of 0.1 M of the WO{sub 3} precursor solution, when deposited as an overlying layer on TiO{sub 2} by two annealing steps (∝76% methylene blue decolorization in 300 min of irradiation versus ∝59% in the case of a bare TiO{sub 2} film). In general, the coupled layer catalysts exhibited superior photoactivity compared to that of bare TiO{sub 2} films with WO{sub 3} acting as an electron trap, resulting, therefore, in a more efficient electron-hole separation and inhibiting their recombination. (orig.)

  8. Visible-light activate Ag/WO3 films based on wood with enhanced negative oxygen ions production properties

    Science.gov (United States)

    Gao, Likun; Gan, Wentao; Cao, Guoliang; Zhan, Xianxu; Qiang, Tiangang; Li, Jian

    2017-12-01

    The Ag/WO3-wood was fabricated through a hydrothermal method and a silver mirror reaction. The system of visible-light activate Ag/WO3-wood was used to produce negative oxygen ions, and the effect of Ag nanoparticles on negative oxygen ions production was investigated. From the results of negative oxygen ions production tests, it can be observed that the sample doped with Ag nanoparticles, the concentration of negative oxygen ions is up to 1660 ions/cm3 after 60 min visible light irradiation. Moreover, for the Ag/WO3-wood, even after 60 min without irradiation, the concentration of negative oxygen ions could keep more than 1000 ions/cm3, which is up to the standard of the fresh air. Moreover, due to the porous structure of wood, the wood acted as substrate could promote the nucleation of nanoparticles, prevent the agglomeration of the particles, and thus lead the improvement of photocatalytic properties. And such wood-based functional materials with the property of negative oxygen ions production could be one of the most promising materials in the application of indoor decoration materials, which would meet people's pursuit of healthy, environment-friendly life.

  9. Hierarchical nanostructures assembled from ultrathin Bi2WO6 nanoflakes and their visible-light induced photocatalytic property

    International Nuclear Information System (INIS)

    Wang, Xiong; Tian, Peng; Lin, Ying; Li, Li

    2015-01-01

    Graphical abstract: Hierarchical Bi 2 WO 6 nanostructures assembled from nanoflakes were successfully synthesized by a facile hydrothermal method. The excellent photocatalytic activity and recycling performance might be mainly ascribed to the unique hierarchical nanostructures and are expected to offer the nanostructures promising applications in the field of wastewater treatment. - Highlights: • Hierarchical Bi 2 WO 6 nanostructures assembled from nanoflakes were successfully synthesized by a facile hydrothermal method. • Visible-light-induced photocatalytic efficiency of the obtained nanoarchitectures was enhanced about 6 times. • A possible mechanism was proposed. - Abstract: With the aid of ethylene glycol and sodium dodecylbenzene sulfonate, the hierarchical Bi 2 WO 6 nanoarchitectures assembled from nanoflakes could be attained by a facile solvothermal method. The synthetic strategy is versatile and environmentally friendly and a plausible growth-assembly process was proposed for the formation of the hierarchical nanostructures. The visible-light-irradiated photocatalytic activity was estimated by the degradation of rhodamine B. Compared with the sample prepared by a solid-state reaction, the visible-light-induced photocatalytic efficiency of the nanostructures was enhanced about 6 times. The photocatalysis tests show that the nanostructures exhibit excellent photocatalytic activity and recycling performance, which were mainly ascribed to the unique hierarchical nanostructures and are expected to offer promising applications in the field of wastewater treatment

  10. Cooperative self-construction and enhanced optical absorption of nanoplates-assembled hierarchical Bi2WO6 flowers

    International Nuclear Information System (INIS)

    Liu Shengwei; Yu Jiaguo

    2008-01-01

    Bi 2 WO 6 hierarchical multilayered flower-like assemblies are fabricated on a large scale by a simple hydrothermal method in the presence of polymeric poly(sodium 4-styrenesulfonate). Such 3D Bi 2 WO 6 assemblies are constructed from orderly arranged 2D layers, which are further composed of a large number of interconnected nanoplates with a mean side length of ca. 50 nm. The bimodal mesopores associated with such hierarchical assembly exhibit peak mesopore size of ca. 4 nm for the voids within a layer, and peak mesopore size of ca. 40 nm corresponding to the interspaces between stacked layers, respectively. The formation process is discussed on the basis of the results of time-dependent experiments, which support a novel 'coupled cooperative assembly and localized ripening' formation mechanism. More interestingly, we have noticed that the collective effect related to such hierarchical assembly induces a significantly enhanced optical absorbance in the UV-visible region. This work may shed some light on the design of complex architectures and exploitation of their potential applications. - Graphical abstract: Bi 2 WO 6 hierarchical multilayered flower-like assemblies are fabricated on a large scale by a simple hydrothermal method in the presence of polymeric poly(sodium 4-styrenesulfonate)

  11. Microporous TiO2-WO3/TiO2 films with visible-light photocatalytic activity synthesized by micro arc oxidation and DC magnetron sputtering

    International Nuclear Information System (INIS)

    Wu, Kee-Rong; Hung, Chung-Hsuang; Yeh, Chung-Wei; Wu, Jiing-Kae

    2012-01-01

    Highlights: ► A simple MAO is used to prepare porous WO 3 /TiO 2 layer on Ti sheet as a visible-light enabled catalyst. ► The photocatalytic activity of the WO 3 /TiO 2 is enhanced by sputtering over an N,C-TiO 2 layer. ► This is ascribed to the synergetic effect of hybrid sample prepared by two-step method. - Abstract: This study reports the preparation of microporous TiO 2 -WO 3 /TiO 2 films with a high surface area using a two-step approach. A porous WO 3 /TiO 2 template was synthesized by oxidizing a titanium sheet using a micro arc oxidation (MAO) process. This sheet was subsequently overlaid with a visible light (Vis)-enabled TiO 2 (N,C-TiO 2 ) film, which was deposited by codoping nitrogen (N) and carbon (C) ions into a TiO 2 lattice using direct current magnetron sputtering. The resulting microporous TiO 2 -WO 3 /TiO 2 film with a 0.38-μm-thick N,C-TiO 2 top-layer exhibited high photocatalytic activity in methylene blue (MB) degradation among samples under ultraviolet (UV) and Vis irradiation. This is attributable to the synergetic effect of two-step preparation method, which provides a highly porous microstructure and the well-crystallized N,C-TiO 2 top-layer. This is because a higher surface area with high crystallinity favors the adsorption of more MB molecules and more photocatalytic active areas. Thus, the microporous TiO 2 -WO 3 /TiO 2 film has promising applications in the photocatalytic degradation of dye solution under UV and Vis irradiation. These results imply that the microporous WO 3 /TiO 2 can be used as a template of hybrid electrode because it enables rapid fabrication.

  12. High-energy lithium-ion hybrid supercapacitors composed of hierarchical urchin-like WO3/C anodes and MOF-derived polyhedral hollow carbon cathodes.

    Science.gov (United States)

    Xu, Juan; Li, Yuanyuan; Wang, Lei; Cai, Qifa; Li, Qingwei; Gao, Biao; Zhang, Xuming; Huo, Kaifu; Chu, Paul K

    2016-09-22

    A lithium-ion hybrid supercapacitor (Li-HSC) comprising a Li-ion battery type anode and an electrochemical double layer capacitance (EDLC) type cathode has attracted much interest because it accomplishes a large energy density without compromising the power density. In this work, hierarchical carbon coated WO 3 (WO 3 /C) with a unique mesoporous structure and metal-organic framework derived nitrogen-doped carbon hollow polyhedra (MOF-NC) are prepared and adopted as the anode and the cathode for Li-HSCs. The hierarchical mesoporous WO 3 /C microspheres assembled by radially oriented WO 3 /C nanorods along the (001) plane enable effective Li + insertion, thus exhibit high capacity, excellent rate performance and a long cycling life due to their high Li + conductivity, electronic conductivity and structural robustness. The WO 3 /C structure shows a reversible specific capacity of 508 mA h g -1 at a 0.1 C rate (1 C = 696 mA h g -1 ) after 160 discharging-charging cycles with excellent rate capability. The MOF-NC achieved the specific capacity of 269.9 F g -1 at a current density of 0.2 A g -1 . At a high current density of 6 A g -1 , 92.4% of the initial capacity could be retained after 2000 discharging-charging cycles, suggesting excellent cycle stability. The Li-HSC comprising a WO 3 /C anode and a MOF-NC cathode boasts a large energy density of 159.97 W h kg -1 at a power density of 173.6 W kg -1 and 88.3% of the capacity is retained at a current density of 5 A g -1 after 3000 charging-discharging cycles, which are better than those previously reported for Li-HSCs. The high energy and power densities of the Li-HSCs of WO 3 /C//MOF-NC render large potential in energy storage.

  13. Facile one-step hydrothermal synthesis and luminescence properties of Eu{sup 3+}-doped NaGd(WO{sub 4}){sub 2} nanophosphors

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Zehan; Cai, Peiqing; Chen, Cuili; Pu, Xipeng; Kim, Sun Il, E-mail: sikim@pknu.ac.kr; Jin Seo, Hyo, E-mail: hjseo@pknu.ac.kr

    2017-06-01

    Eu{sup 3+}-doped NaGd(WO{sub 4}){sub 2} nanophosphors were synthesized via a facile one-step hydrothermal method without any surfactants or a further heat treatment. X-ray powder diffraction (XRD), scanning electron microscope (SEM), fourier transform infrared spectroscopy (FT-IR), the photoluminescence (PL) excitation and emission spectra, and decay curves were used to characterize NaGd(WO{sub 4}){sub 2}:Eu{sup 3+} phosphors. The results show that the Eu{sup 3+}-concentration has little influence on the structure and morphology of the as-synthesized samples. However, pH value plays a vital role on the structure and morphology of NaGd(WO{sub 4}){sub 2}. The well-crystallized sheet-like NaGd(WO{sub 4}){sub 2} phosphors can be obtained only at pH = 5–7. On the basis of the time-dependent synthesis, a possible growth mechanism of sheet-like architectures is proposed. The luminescence properties of NaGd{sub 1-x}Eu{sub x}(WO{sub 4}){sub 2} (0 ≤ x ≤ 1) are investigated. It is found that the charge transfer band of Eu{sup 3+} shifts to lower energy and broadens with increasing the Eu{sup 3+}-concentration. - Highlights: • NaGd(WO{sub 4}){sub 2}:Eu{sup 3+} nanosheets were synthesized by facile one-step hydrothermal method. • Luminescence properties of NaGd(WO{sub 4}){sub 2}:Eu{sup 3+} phosphor were firstly reported. • The CT band of Eu{sup 3+} depends strongly on Eu{sup 3+}-concentrations.

  14. Effect of Na2WO4 in Electrolyte on Microstructure and Tribological Behavior of Micro-arc Oxidation Coatings on Ti2AlNb Alloy

    Directory of Open Access Journals (Sweden)

    LIU Xiao-hui

    2018-02-01

    Full Text Available Micro-arc oxidation (MAO ceramic coatings were prepared on Ti2AlNb alloy in silicate/phosphate electrolytes with different concentrations of Na2WO4. The influence of Na2WO4 on the coating growth process, coating structure and composition was analyzed by SEM, XRD and XPS. The tribological behavior of MAO coatings was evaluated by the ball-disc wear test. The results show that the growth rate of MAO coating in electrolyte without Na2WO4 is only 0.08μm/min, meanwhile, the coating is loose and rough, and "networks" connecting with big pores exist on the coating surface.The main phase compositions of this coating are rutile TiO2, anatase TiO2, Al2O3, and Nb2O5. The addition of Na2WO4 in the electrolyte shortens the time before sparking of Ti2AlNb alloy, increases the growth rate of the coating, improves the uniformity of coating and meanwhile, a small amount of WO3 is introduced in the coating. Besides, MAO coatings formed in the participation of Na2WO4 have better wear resistance. Severe abrasive wear occurs when the test is made on Ti2AlNb alloy with Si3N4, the friction coefficient reaches 0.5-0.7. Both the friction coefficient and wear rate decrease obviously when Ti2AlNb is treated by MAO. The friction coefficient and wear rate of MAO coating prepared in the electrolyte with 4g/L Na2WO4 are 0.24 and 6.2×10-4mm3/(N·m, respectively. Only "fish scales" caused by fatigue wear appears on the coating surface.

  15. Synthesis and luminescent properties of two different Y{sub 2}WO{sub 6}:Eu{sup 3+} phosphor phases

    Energy Technology Data Exchange (ETDEWEB)

    Llanos, Jaime, E-mail: jllanos@ucn.cl [Departamento de Química, Universidad Católica del Norte, Avda. Angamos 0610, Antofagasta (Chile); Olivares, Douglas [Departamento de Química, Universidad Católica del Norte, Avda. Angamos 0610, Antofagasta (Chile); Manríquez, Víctor; Espinoza, Darío [Departamento de Química, Universidad de Chile, Las Palmeras 3425, Santiago (Chile); Brito, Ivan [Departamento de Química, Universidad de Antofagasta, Campus Coloso, Antofagasta (Chile)

    2015-04-15

    Highlights: • Synthesis of two phases Y{sub 2−x}Eu{sub x}WO{sub 6}. One of them crystallizes as Aurivillius phase. • Optical properties of the phosphors Y{sub 2}WO{sub 6}:Eu{sup 3+} (monoclinic and orthorhombic phases). • The orthorhombic phase was prepared via low-temperature combustion synthesis method. - Abstract: In this paper, two different Y{sub 2−x}Eu{sub x}WO{sub 6} phases were synthesized. The monoclinic phase was prepared via a conventional solid-state reaction, whereas the orthorhombic phase was obtained via a facile, low-temperature combustion synthesis method. X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and photoluminescence (PL) spectroscopy were used to characterize the resulting phosphors. The XRD results indicate the orthorhombic phase crystallized isostructurally with the Aurivillius Bi{sub 2}WO{sub 6} phase, whereas the other polymorph crystallized isostructurally with Yb{sub 2}WO{sub 6} in the monoclinic system. The SEM studies revealed both phases had a strong tendency to form agglomerates averaging nanometers in size. The photoluminescence emission spectra confirmed all of the samples were efficiently excited by near UV light and were dominated by the electric dipole transition {sup 5}D{sub 0} → {sup 7}F{sub 2}. The orthorhombic Y{sub 2−x}Eu{sub x}WO{sub 6} excitation spectrum possessed a broad band across the entire UV region (220–400 nm); therefore, Y{sub 1.86}Eu{sub 0.14}WO{sub 6} could be considered an efficient spectral converter material for use in dye-sensitized solar cells.

  16. Irreversible thermochromic response of RF sputtered nanocrystalline BaWO4 films for smart window applications

    Directory of Open Access Journals (Sweden)

    C. Anil Kumar

    2015-10-01

    Full Text Available We report irreversible thermochromic behaviour of BaWO4 (BWO films for the first time. BWO films have been deposited at different substrate temperatures (RT, 200, 400, 600 and 800 °C using RF magnetron sputtering in pure argon plasma. BWO films deposited at 800 °C exhibit crystalline nature. Also, BWO films deposited in the temperature range of 400 - 600 °C exhibit WO3 as a secondary phase and its weight percentage decreases with an increase in deposition temperature, whereas the films deposited at 800 °C exhibited pure tetragonal phase. FESEM images revealed that as the average particle sizes of the films are higher as compared with the thickness of the films and is explained based on Avrami type nucleation and growth. The transmittance of the films decreases with an increase in deposition temperature up to 600 °C and increases thereafter. Films deposited at 600 °C show ≤ 20% transmittance, looking at the films deposited at room temperature and 800 °C exhibits 90 and 70%, respectively. The refractive index and extinction coefficient of the films show profound dependence on crystallinity and packing density. The optical bandgap of BWO films increases significantly with an increase in O2% during the deposition. The optical bandgap of the BWO films deposited at different temperatures in pure argon plasma, are in the range of 3.7 to 3.94 eV whereas the films deposited at 600 °C under different O2 plasma are in the range of 3.6 - 4.5 eV. The formations of colour centres are associated with the oxygen vacancies, which are clearly seen from the optical bandgap studies. The observed irreversible thermochromic behaviour in BWO films is attributed to the presence of oxygen vacancies that arises due to the electrons trapped at oxygen vacancies causing an inter valence charge transfer of W5+ to W6+ and is confirmed through the change in the optical density (ΔOD. Further, the Raman spectra are being used to quantify the presence

  17. A photocatalytic approach in micro arc oxidation of WO3-TiO2 nano porous semiconductors under pulse current

    International Nuclear Information System (INIS)

    Bayati, M.R.; Golestani-Fard, F.; Moshfegh, A.Z.; Molaei, R.

    2011-01-01

    Graphical abstract: WO3-TiO2 layers were fabricated via microarc oxidation process and effect of the electrical current type on their photocatalytic performance under UV and visible illuminations was investigated. Highlights: → WO3-TiO2 layers were grown by MAO under pulse current for the first time. → Effect of the frequency and duty cycle on properties of the layers was studied. → A correlation between catalytic performance and growth conditions was proposed. - Abstract: Since ultraviolet (UV) irradiation cannot be applied for a long time in practical applications, it is necessary to develop a narrow band gap photocatalyst to decompose environmental pollutants under visible irradiation. In this research, (WO 3 ) x -(TiO 2 ) 1-x nano-porous layers were fabricated by micro arc oxidation (MAO) and influence of the electrical current type on their physical and chemical properties was investigated. Morphological studies, performed by SEM technique, revealed that pore size and roughness decreased with the frequency and increased with the duty cycle. The pulse-grown layers had a finer structure when compared to those fabricated under direct current. XRD and XPS results showed that the layers consisted of anatase, rutile, and tungsten oxide phases. Applying pulse current resulted in higher anatase relative contents. Band gap energies of the MAO-grown TiO 2 and WO 3 -TiO 2 layers were respectively measured as 3.14 and 2.96 eV. The layers fabricated under pulse current exhibited higher photoactivity under ultraviolet and visible illuminations as compared to the layers grown under direct current. Methylene blue (MB) was used as a model material to examine photocatalytic performance of the layers. Maximum MB-photodegradation reaction rate constants over the pulse-synthesized WO 3 -TiO 2 layers were measured as 0.0269 and 0.0129 min -1 for ultraviolet and visible irradiations. For layers grown under direct current, the rate constants were lower, i.e. 0.0228 and 0

  18. Increasing student engagement in science through field-based research: University of Idaho's WoW STEMcore Program

    Science.gov (United States)

    Squires, A. L.; Boylan, R. D.; Rittenburg, R.; Boll, J.; Allan, P.

    2013-12-01

    A recent statewide survey assessing STEM perceptions in Idaho showed that high school student interest in science and preparation for college are declining. To address this decline we are piloting an interdisciplinary, community and field-based water science education approach for 10th - 12th grade science courses during the 2013-14 school year called WoW STEMcore. The program is led by graduate students in the University of Idaho (UI) Waters of the West (WoW) program. Our methods are based on proven best practices from eight years of NSF GK-12 experience at UI and over a decade of GK-12 experience at more than 300 programs in the U.S. WoW STEMcore works to strengthen partnerships between WoW graduate students, high school teachers, and regional organizations that work on natural resource management or place-based science education with the intent of sustaining and merging efforts to increase scientific literacy among high school students and to better prepare them for higher education. In addition, graduate students gain outreach, education and communication experience and teachers are exposed to new and relevant research content and methods. WoW STEMcore is fostering these partnerships through water themed projects at three northern Idaho high schools. The pilot program will culminate in Spring 2014 with a regional Water Summit in which all participating students and partners will converge at a two-day youth scientific conference and competition where they can showcase their research and the skills they gained over the course of the year. We hypothesize that through a graduate student-led, field-based program that gets students out of the classroom and thinking about water resource issues in their communities, we will 1) fuel high school students' interest in science through hands on and inquiry-based pedagogy and 2) improve preparation for higher education by providing graduate student mentors to discuss the pathway from high school to college to a career. In

  19. Determination and modeling for the solubility of Na_2WO_4·2H_2O and Na_2MoO_4·2H_2O in the (Na"+ + MoO_4"2"− + WO_4"2"− + SO_4"2"− + H_2O) system

    International Nuclear Information System (INIS)

    Ning, Pengge; Xu, Weifeng; Cao, Hongbin; Xu, Hongbin

    2016-01-01

    Highlights: • The solubility of Na_2MoO_4·2H_2O and Na_2WO_4·2H_2O in Na_2MoO_4–Na_2WO_4–Na_2SO_4–H_2O were performed. • The solubility of sodium tungstate dihydrate in Na_2WO_4–Na_2SO_4–H_2O was determined. • The new model was established via regressing the published and the determined data. • The Pitzer parameter and the solubility product constant of the salt in solution were calculated. • The model was used to estimate the solubility of the sodium molybdate and sodium tungstate. - Abstract: The solubility of sodium tungstate dihydrate and sodium molybdate dihydrate in the (Na_2MoO_4 + Na_2WO_4 + Na_2SO_4 + H_2O) system was studied using experimental and calculated methods. The osmotic coefficient of sodium tungstate was fitted to calculate the thermodynamics parameters of (Na_2WO_4 + H_2O) system. The solubility of sodium tungstate dihydrate was determined using the dynamic method in Na_2WO_4–Na_2SO_4–H_2O to establish the new model which can provide an estimate the solubility of sodium tungstate dihydrate in various conditions, combined with the data published, the solubility of sodium tungstate dihydrate and the sodium molybdate dihydrate in quaternary system of (Na_2MoO_4 + Na_2WO_4 + Na_2SO_4 + H_2O) was estimated using the parameters of the two ternary systems of (Na_2WO_4 + Na_2SO_4 + H_2O) and (Na_2MoO_4 + Na_2SO_4 + H_2O). The results show that the AARD is always small and the calculated value is basically consistent with the experimental values for the system studied.

  20. In situ loading of Ag_2WO_4 on ultrathin g-C_3N_4 nanosheets with highly enhanced photocatalytic performance

    International Nuclear Information System (INIS)

    Li, Yunfeng; Jin, Renxi; Fang, Xu; Yang, Yang; Yang, Man; Liu, Xianchun; Xing, Yan; Song, Shuyan

    2016-01-01

    Graphical abstract: Ultrathin g-C_3N_4 nanosheets (g-C_3N_4−NS) with improved electron transport ability and large number of active sites are employed instead of bulk g-C_3N_4 to prepare the Ag_2WO_4/g-C_3N_4−NS heterostructured photocatalysts, which exhibit remarkable photocatalytic activity for wastewater treatment. - Highlights: • Ag2WO4/g-C3N4-NS photocatalysts were obtained by a deposition-precipitation method. • Ag2WO4/g-C3N4-NS possess large surface areas and increased lifetime of charges. • Ag2WO4/g-C3N4-NS exhibit enhanced activity on degradation of RhB and MO. • The photocatalytic mechanism of the Ag2WO4/g-C3N4-NS system were investigated. - Abstract: The g-C_3N_4 nanosheets (g-C_3N_4−NS) exhibit more excellent property than common bulk g-C_3N_4 (g-C_3N_4-B) due to their large surface areas, improved electron transport ability and well dispersion in water. In this work, ultrathin g-C_3N_4−NS with a thickness of about 2.7 nm have been synthesized by a simple thermal exfoliation of bulk g-C_3N_4, and then Ag_2WO_4 nanoparticles are in situ loaded on their surface to construct the Ag_2WO_4/g-C_3N_4−NS heterostructured photocatalysts. Due to their unique physicochemical properties, the as-prepared heterostructures possess a fast interfacial charge transfer and increased lifetime of photo-excited charge carriers, and exhibit much higher photocatalytic activity. Under visible light irradiation, the optimum photocatalytic activity of Ag_2WO_4/g-C_3N_4−NS composites is almost 53.6 and 26.5 times higher than that of pure g-C_3N_4-B and Ag_2WO_4/g-C_3N_4-B heterostructures towards the degradation of rhodamine B, respectively, and is almost 30.6 and 9.8 times higher towards the degradation of methyl orange, respectively. In addition, the natural sunlight photocatalytic activities of the as-prepared samples are also investigated.

  1. Photoluminescence characteristics of Sm{sup 3+}-doped Ba{sub 2}CaWO{sub 6} as new orange–red emitting phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Ruiijn [College of Science, Northwest A and F University, Yangling, Shaanxi 712100 (China); Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Mi Noh, Hyeon; Kee Moon, Byung; Chun Choi, Byung [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Hyun Jeong, Jung, E-mail: jhjeong@pknu.ac.kr [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Sueb Lee, Ho [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Jang, Kiwan, E-mail: kwjang@changwon.ac.kr [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Soo Yi, Soung [Department of Electronic Material Engineering, Silla University, Busan 617-736 (Korea, Republic of)

    2014-08-01

    The orange–red emitting Ba{sub 2}CaWO{sub 6}:xSm{sup 3+} (0.01≤x≤0.25) phosphors were synthesized via solid state reaction process. The crystal structure of the phosphor was characterized by XRD. The photoluminescence excitation and emission spectra, concentration effect were investigated. The results show an efficient energy transfer from WO{sub 6}{sup 6−} group to Sm{sup 3+} occurs. The emission spectra of the Ba{sub 2}CaWO{sub 6}:Sm{sup 3+} phosphors consisted of some sharp emission peaks of Sm{sup 3+} ions centre at 579 nm, 618 nm, 625 nm, and 675 nm. The strongest one is located at 610 nm due to {sup 4}G{sub 5/2}→{sup 6}H{sub 7/2} transition of Sm{sup 3+}, generating bright orange–red light. The optimum dopant concentration of Sm{sup 3+} ions in Ba{sub 2}CaWO{sub 6}:xSm{sup 3+} is around 5 mol% and the critical transfer distance of Sm{sup 3+} is calculated as 18 Å. The fluorescence lifetime of Sm{sup 3+} in Ba{sub 2}CaWO{sub 6}:0.05Sm{sup 3+} is 2.36 ms. The Ba{sub 2}CaWO{sub 6}:Sm{sup 3+} phosphors may be potentially used as orange–red phosphors for white light-emitting diodes. - Highlights: • A new host-sensitized Sm{sup 3+}-doped Ba{sub 2}CaWO{sub 6} phosphor was firstly synthesized. • Its structure, luminescent properties are well studied and characterized. • There exists an efficient energy transfer from WO{sub 6}{sup 6−} group to Sm{sup 3+}. • The thermal quenching properties of Ba{sub 2}CaWO{sub 6}:Sm{sup 3+} was firstly evaluated.

  2. Study of multiferroic properties of Bi2Fe2WO9 ceramic for device application

    Directory of Open Access Journals (Sweden)

    Jyoshna Rout

    2016-09-01

    Full Text Available The Bi2Fe2WO9 ceramic was prepared using a standard solid-state reaction technique. Preliminary analysis of X-ray diffraction pattern revealed the formation of single-phase compound with orthorhombic crystal symmetry. The surface morphology of the material captured using scanning electron microscope (SEM exhibits formation of a densely packed microstructure. Comprehensive study of dielectric properties showed two anomalies at 200∘C and 450∘C: first one may be related to magnetic whereas second one may be related to ferroelectric phase transition. The field dependent magnetic study of the material shows the existence of small remnant magnetization (Mr of 0.052emμ/g at room temperature. The existence of magneto-electric (ME coupling coefficient along with above properties confirms multi-ferroic characteristics of the compound. Selected range temperature and frequency dependent electrical parameters (impedance, modulus, conductivity of the compound shows that electric properties are correlated to its microstructure. Detailed studies of frequency dependence of ac conductivity suggest that the material obeys Jonscher’s universal power law.

  3. Renewable energy production by photoelectrochemical oxidation of organic wastes using WO3 photoanodes.

    Science.gov (United States)

    Raptis, Dimitrios; Dracopoulos, Vassilios; Lianos, Panagiotis

    2017-07-05

    The present work has studied renewable hydrogen production by photoelectrocatalytic degradation of model organic substances representing biomass derived organic wastes. Its purpose was to show that renewable energy can be produced by consuming wastes. The study has been carried out by employing nanoparticulate WO 3 photoanodes in the presence of ethanol, glycerol or sorbitol, i.e. three substances which are among typical biomass products. In these substances, the molecular weight and the number of hydroxyl groups increases from ethanol to sorbitol. The photocurrent produced by the cell was the highest in the presence of ethanol, smaller in the case of glycerol and further decreased in the presence of sorbitol. The photocurrent was roughly the double of that produced in the absence of an organic additive thus demonstrating current doubling phenomena. Hydrogen was produced only under illumination and was monitored at two forward bias, 0.8 and 1.6V vs Ag/AgCl. Hydrogen production rates followed the same order as the photocurrent thus indicating that hydrogen production by reduction of protons mainly depends on the current flowing through the external circuit connecting photoanode with cathode. The maximum solar-to-hydrogen efficiency reached by the present system was 2.35%. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Demulsification based on the thermal treatment (cooling and heating of W/O emulsions

    Directory of Open Access Journals (Sweden)

    Rajaković Vladana N.

    2004-01-01

    Full Text Available An important step in waste water treatment is the removal of oil from an O/W emulsion and the separation of oil and water into two phases, a process usually called demulsification. Modern methods of oil removal from waste water were described in the present study. Typical demulsification techniques include thermal, electrical, chemical, acoustic, or mechanical methods of emulsion treatment. The freeze/thaw process was found to be very effective for demulsification. In the freeze/thaw process, water removal from the W/O emulsion depends on the initial oil content, freezing temperature, freezing time, thawing rate and temperature. The described method is a non-destructive and physical method of emulsion treatment and because there is no addition of chemical agents there is no problem of further waste water treatment, which usually exists when chemicals are applied for demulsification. Different methods for oil content determination in the O/W emulsion were also applied and compared in this study (gravimetric, volumetric, measurement of oxygen consumption and emulsion pH, IR analysis of the emulsion, electro analytical measurement.

  5. Novel ZnWO4/RGO nanocomposite as high performance photocatalyst

    Directory of Open Access Journals (Sweden)

    Mohamed Jaffer Sadiq Mohamed

    2017-01-01

    Full Text Available In this study, we report the synthesis of nanocomposite material composed of zinc tungstate (ZnWO4 and reduced graphene oxide (RGO as photocatalyst by a simple microwave irradiation technique. The prepared nanocomposites have been characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, energy dispersive X-ray (EDX analysis, X-ray photoelectron spectroscopy (XPS, Fourier transform infrared spectrometer (FTIR, photoluminescence spectroscopy (PL and UV-Visible spectroscopy. The photocatalytic activities of the prepared nanocomposites are evaluated in terms of the efficiencies of photodegradation of methylene blue (MB dye in aqueous solution under visible light irradiation. The prepared nanocomposites showed excellent photodegradation efficiency compared to the commercial TiO2 under visible light irradiation. The activity of the catalyst towards methyl orange (MO and rhodamine B (RB was also good. Further, in view of the low cost, simple preparation method and high catalytic activity of the material, it is expected that the prepared nanocomposite can serve as an environment friendly photocatalyst for treating the large scale industrial waste waters.

  6. Photoluminescence varied by selective excitation in BiGdWO6:Eu3+ phosphor

    Science.gov (United States)

    Pavani, K.; Graça, M. P. F.; Kumar, J. Suresh; Neves, A. J.

    2017-12-01

    Eu3+ doped bismuth gadolinium tungstate (BGW), a simplest member of Aurivillius family of layered perovskites, was synthesized by solid-state reaction method. Structural characterisation has been performed by X-Ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Band gap of the host matrix has been calculated using reflectance and absorption spectra. Three different mechanisms were found to explain the excitation of Eu3+ ions and are described in detail. Photoluminescence (PL) spectra of the BGW phosphor doped with Eu3+ ions consist of major emission lines associated with 5D0 → 7FJ (J = 0, 1, 2, 3 and 4) of Eu3+ ion. Site selective PL excitation and emission indicates that Eu3+ ions doped in BiGdWO6 are sensitive to the excitation wavelength without change in the structure. Change in emission spectra were observed when the excitation wavelength was changed. Judd-Ofelt (J-O) parameters were determined from the indirect method to interpret the interactions between the host and dopant ions along with detailed analysis of lifetime measurements.

  7. Characterization of PbWO4 crystals for high-energy physics experiments

    Science.gov (United States)

    Kim, M. J.; Park, H.; Kim, H. J.

    2016-09-01

    High-energy physics (HEP) experiments have employed many new types of scintillators. Specifically, bismuth germanate, thallium-doped cesium iodide, and lead tungstate (PbWO4, PWO) have been used for the L3 experiment; CLEO II, Belle and BES-III; and CMS, respectively. PWO has particularly beneficial properties, such as high density, fast decay time, short radiation length and radiation hardness. In this study, we tested the PWO crystals at low temperatures to determine their applicability in future calorimeters. Various crystals from the Proton Antiproton Annihilations at Darmstadt (PANDA) experiment in Giessen, the Bogoroditsk Techno-Chemical Plant (BTCP) in Russia and by Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS) in China were investigated. We studied the scintillation properties of PWO crystals, such as their X-ray luminescence, relative light yields, absolute light yields, energy resolutions, decay times and longitudinal uniformities of their light yields. In addition, we measured the temperature dependences of the light yields and decay times by using a 137Cs γ-ray source. The emission spectra of the PWO crystals consisted of a broad band from 350 nm to 700 nm, and the peak emission wavelength in each spectrum was 420 nm. The emission spectra of the PWO crystals from SICCAS were slightly shifted to longer wavelengths compared with those of the crystals from the other institutions.

  8. Modulation of GDP-fucose level for generating proteins with reduced rate of fucosylation (WO2010141855).

    Science.gov (United States)

    Taupin, Philippe

    2011-09-01

    The application (WO2010141855) is in the field of glycobiology, and involves the control of the rate of fucosylation of proteins by exogenous factors. It aims at controlling the rate of protein fucosylation with inhibitors (drugs or nucleic acid antagonists) of enzymes involved in the synthesis of GDP-fucose. Mammalian cell lines were cultured in the presence of inhibitors, for example, siRNA. The rates of GDP-fucose in cells and during protein fucosylation were characterized. The level of protein fucosylation decreases rapidly in response to a decrease in GDP-fucose level. The relationship between the rate of fucosylation of proteins and the level of GDP-fucose in a cell is non-linear. Reduction in the rate of protein fucosylation can be achieved with a minimal reduction of the level of GDP-fucose in cells. The paradigm may be used to synthesize proteins and antibodies, with a reduced rate of fucosylation. The application claims that the use