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Sample records for eikyo wo koryoshita

  1. Optimal type for safety monitoring systems considering uncertainty. Fukakujitsusei wo koryoshita anzen kanshi system no saiteki type mondai

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, K. (Ibaraki University, Ibaraki (Japan). Faculty of Engineering)

    1990-12-20

    Discussions were given on the problem of selecting a most suitable type of safety monitoring system. A monitoring system monitors object systems using r'' number of sensors of the same characteristics, and determines state of the object systems based on the state string of each sensor. An algorithm was introduced, that determines an optimal composition function (f) of the system, which minimizes the expected loss value caused from two failure modes: a malfunction to issue an alarm when the object is safe, and a non-function not issuing an alarm when the object is in danger. The monotony of f'' is retained not only to a binary state of whether safe or dangerous, but also to a monitoring system comprising sensors that output signals recognizing multivalued state, under a certain condition. The object systems have an existence of uncertain state {Theta} that can not be definitely determined whether safe or dangerous. The sensor system was divided into a type 1 unit that identifies the state {Theta} as safe, and a type 2 unit that identifies it as dangerous, and a method was proposed to select which safety monitoring system is most suitable among the combinations of these units. 12 refs., 5 figs.

  2. Prediction of strong acceleration motion depended on focal mechanism; Shingen mechanism wo koryoshita jishindo yosoku ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Kaneda, Y.; Ejiri, J. [Obayashi Corp., Tokyo (Japan)

    1996-10-01

    This paper describes simulation results of strong acceleration motion with varying uncertain fault parameters mainly for a fault model of Hyogo-ken Nanbu earthquake. For the analysis, based on the fault parameters, the strong acceleration motion was simulated using the radiation patterns and the breaking time difference of composite faults as parameters. A statistic waveform composition method was used for the simulation. For the theoretical radiation patterns, directivity was emphasized which depended on the strike of faults, and the maximum acceleration was more than 220 gal. While, for the homogeneous radiation patterns, the maximum accelerations were isotopically distributed around the fault as a center. For variations in the maximum acceleration and the predominant frequency due to the breaking time difference of three faults, the response spectral value of maximum/minimum was about 1.7 times. From the viewpoint of seismic disaster prevention, underground structures including potential faults and non-arranging properties can be grasped using this simulation. Significance of the prediction of strong acceleration motion was also provided through this simulation using uncertain factors, such as breaking time of composite faults, as parameters. 4 refs., 4 figs., 1 tab.

  3. Study on spontaneous potential exploration considering resistivity structures; Hiteiko kozo wo koryoshita shizen den`iho tansa

    Energy Technology Data Exchange (ETDEWEB)

    Sato, H.; Sakurai, K.; Shimada, H. [OYO Corp., Tokyo (Japan)

    1996-10-01

    Spontaneous potential (SP) was measured on the known traverse line of resistivity structure crossing Hanaori fault in Ohara area, Kyoto city to observe change in SP around the fault and to examine the possibility of fault position exploration. The supposed causes of generation of SP are as follows: the existence of sulfide mineral deposit including polarized minerals, underground fluid flow, and the existence of stratum including chemical compositions from hot springs. The SP method estimates underground structures based on measured surface potential distributions using DC component under anomaly of SP. FEM modeling clarified that a fault fracture zone is one of the causes of generation of SP, by considering SP measurement and resistivity structure strongly affecting observed SP. Consequently, combination of SP measurement with resistivity structure exploration allows a reliable fault estimation method. Under the assumption that anomaly of SP is caused by polarization around fault, the horizontal dipole model based on polarization of current source dipole along fault can well explain the measured data. 2 refs., 6 figs.

  4. Study of human interface for narrow road drive assist system considered characteristic of driver; Driver no tokusei wo koryoshita kyoro soko shien system no human interface no kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, A. [Subaru Research Center Co., Tokyo (Japan); Amada, N.; Kawashima, H. [Keio University, Tokyo (Japan)

    1997-10-01

    The measurement of driver`s watching point, driving time on narrow road and the evaluation of stress etc. were conducted in order to construct the narrow road drive assist system using the stereo image recognition system. Consequently, the driver`s thinking process, stress factor and the indispensable information for this system were clarified. 4 refs., 8 figs., 3 tabs.

  5. Improvements of diesel combustion with pilot and main injections at different piston positions; Piston iso wo koryoshita pilot funsha ni yoru diesel nenshono kaizen

    Energy Technology Data Exchange (ETDEWEB)

    Li, C.; Ogawa, H.; Miyamoto, N. [Hokkaido University, Sapporo (Japan); Sakai, A. [Nissan Motor Co. Ltd., Tokyo (Japan)

    2000-06-25

    The fuel spray distribution in a DI diesel engine with a pilot injection was actively controlled by pilot and main fuel injections at different piston positions to avoid the main fuel injection from hitting the pilot flame. A CFD analysis demonstrated that the movement of the piston with a cavity divided by a central lip along the center of the sidewall effectively separated the cores of the pilot and main fuel sprays. The experiments showed that more smoke was emitted with pilot injection in an ordinary cavity without the central lip while smokeless and low NO{sub x} operation was realized with pilot injection in a cavity divided by a central lip even at heavy loads where ordinary operation without pilot injection emitted smoke so much. The indicated specific energy consumption ISEC was a little bit higher with the pilot injection, mainly because of the reduction in the degree of constant volume combustion. With the advanced pilot injection, ISEC was improved more than that with the retarded pilot injection while the NO{sub x} is a little higher than the retarded pilot injection maintaining still much lower than in ordinary operation. (author)

  6. Thermal sensation vote simulation on the aged for bus air conditioning; Koreisha wo koryoshita onkan suchi simulation no bus kucho eno tekiyo

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, H.; Nishijima, H.; Kitada, M.; Shinma, A. [Denso Corp., Aichi (Japan)

    1997-10-01

    The Numbers of passengers on the aged of sight-seeing buses about 5 times bigger than those of car passengers, have been increasing gradually. The former paper of DENSO in 1994 introduces quantitative method, which simulates passenger heat amount given by sun light at various solar positions. At this time, this paper introduces quantitative method, which simulates passengers thermal sensation skin temperature and also heat amount given by sun light at various solar positions. 5 refs., 8 figs., 2 tabs.

  7. Basic studies on computer aided concurrent engineering for hull structure design and piping design; Kakugi ittai wo koryoshita doji heikotekina sekkei no shien ni kansuru kisoteki kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Aoyama, K.; Sawada, K. [The University of Tokyo, Tokyo (Japan)

    1996-12-31

    Considering integrated hull and piping design in shipbuilding industry as a good example for concurrent engineering (CE), discussions were given on a computer aided method to perform integrated hull and piping design smoothly. When CE aiding by means of a computer is considered, it is important to discuss a method for information management not only for `utilization of product models`, but also for `maintaining consistency between items of product information` and `concurrent utilization and production of product information` in concurrent designs. For the CE aided information management, utilization and production of the product information is effective if restrictive relationship between items of product information, and design functions are made clear. Definitions were given on the restrictive relationship between items of product information and `restrictive relationship information` that has `decision/provisional decision`, `date and time`, `designer` and `design functions`. Furthermore, `comprehensive relationship between items of product information` that can be produced from the restrictive relationship information was defined as a `restrictive network`. Utilizing the restrictive relationship between items of product information for CE aiding is effective. 9 refs., 14 figs.

  8. Application of vertical electrical sounding combined with induced polarization method in ground water exploration; IP koka wo koryoshita hiteikoho suichoku tansa no chikasui chosa eno tekiyo

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, M.; Sakurada, H. [Sumiko Consultants Co. Ltd., Tokyo (Japan); Suzuki, T. [Hokkaido Development Bureau, Hokkaido Development Agency, Sapporo (Japan)

    1996-10-01

    For ground water exploration using vertical Schlumberger exploration method, measurement and analysis combined with induced polarization (IP) effect were conducted as trial. For the Schlumberger method, potential is measured at the center between potential electrodes during flow of dc current between current electrodes. In the case of vertical exploration, measurements are repeated with fixed potential electrodes by extending the distance between current electrodes. Ground water exploration was conducted using this method at Otaki village, Hokkaido. Geology of surveyed plateau consists of a basement of Pliocene tuffs and Quaternary Pleistocene sediments covering on the surface. For the results of analysis, four to seven beds were detected from the resistivity. The depth up to the lowest bed was between 25 and 85 m, the resistivity of each bed was between 9 and 8,000 ohm{times}m, and the polarizability was between 1 and 15 mV/V. Among these resistivity zones, it was judged that zones satisfying following three conditions correspond to coarse grain sediments saturated with ground water, and can be expected as aquifers; having resistivity ranging between 100 and 1,000 ohm{times}m, polarizability higher than 10 mV/V, and relatively large thickness. 11 refs., 6 figs.

  9. Required grades of hull steel plates in consideration of fracture toughness; Hakai jinsei wo koryoshita sentaiyo koban shiyo kubun ni kansuru ichikosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Yajima, H.; Yamamoto, M.; Ogaki, Y. [Hiroshima University, Hiroshima (Japan). Faculty of Engineering

    1997-10-01

    This paper discusses the required grades of hull steel plates based on the steel ship rule of Nippon Kaiji Kyokai (NK). The minimum value of the allowable crack length in NK rule (critical safety crack length at 0degC just before brittle unstable crack causing fatal fracture) was estimated. In the case where the estimated crack tip exists in a matrix, the crack length was a minimum of 200-210mm, while nearly 60mm in a fusion line at high-heat-input welded joint. The allowable crack lengths estimated from a specified value in the NK rule were fairly different. The allowable crack length at 0degC was also estimated from the minimum value in V-notch Charpy impact test. The private proposal on the required grades of hull steel plates in consideration of fracture toughness was discussed. Thirty-five percent of crack lengths found in real ships is 100mm or less, however, cracks of 250-400mm long are frequently found suggesting the allowable crack length of 400mm. The required grade integrally considering required values and design conditions is demanded to secure the reliability of hull strength. 5 refs., 5 figs., 2 tabs.

  10. 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.

  11. 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

  12. Cu3Sm(WO4)3-Sm2(WO4)3 system

    International Nuclear Information System (INIS)

    Arzumanyan, G.A.

    1982-01-01

    Vast regions (up to 25 mol%) of the existence of limited solid solutions with Dalton compositions Cu 3 Sm(WO 4 ) 3 , Cu 13 Sm 7 x(WO 4 ) 17 , Cu 9 Sm 11 (WO 4 ) 21 and Cu 3 Sm 17 (WO 4 ) 27 possessing the structures related to scheelite distorted monoclinic structure of Eu 2 (WO 4 ) 3 A-phase were revealed in the Cu 3 Sm(WO 4 ) 3 -Sm 2 (WO 4 ) 3 system at 500-1100 deg C temperatures and oxigen partial pressure of 0.9-1.3 Pa (total pressure of the noble gas - 102.1+-0.6 kPa)

  13. History of development of railway bridges design standard in China; Chugoku kindai no tetsudokyo no sekkei kijun no hensen. Gaikoku no eikyo wo chushin to shite

    Energy Technology Data Exchange (ETDEWEB)

    Han, Z. [Osaka (Japan); Baba, S. [Okayama Univ. (Japan)

    1998-10-20

    In the year 1876, 4 years later than Japan, first railway line of China was born. After that, by the year 1949, railway about 26,000 km long was constructed in the period called `modernization of China`. China was having partial contracts with Russia, Germany, England, France, Japan and so forth and they have rights to construct railway in China. China that time did not have money for constructing railway by itself because the public economy was not developed, therefore it has to construct railway line by borrowing money from these countries, as a result, the construction right and maintenance right of the railway went to credit country. Each country used their own design standard as it is while constructing bridges in the railway line constructed by them. Accordingly, the railway bridges of China differ in geometric form and structure depending on the country constructing them. Along with the nonuniformity of gauge there was inconvenience in connection transportation between railway lines. In this report, study was made centering to the history of design standard based on the written records and reports of that time. 20 refs., 4 figs., 3 tabs.

  14. Method for estimation of the spectral distribution that influence electric power of PV module; Taiyo denchi shutsuryoku ni eikyo wo ataeru bunko nissha bunpu no suiteiho

    Energy Technology Data Exchange (ETDEWEB)

    Yamagami, Y.; Tani, T. [Science University of Tokyo, Tokyo (Japan)

    1997-11-25

    A method was proposed for estimating the spectral distribution using air mass, precipitable water, and clear indexes which are generally obtainable, and a comparative study was made between the spectral distribution obtained by this method and the measured data using output power of PV modules, etc. as indexes. When solar light comes into the atmosphere, it dissipates receiving scattering/absorption by various gases and aerosols. Direct light component and scattered light component which arrive at the earth surface become functions of air mass and precipitable water. The wavelength distribution of scattered light in cloudy sky is not dependent upon air mass, but affected strongly by absorption band by steam of clouds. By relational equations considered of these, output power and short-circuit current of PV modules are obtained to make a comparison with the measured data. As a result, it was found that this method estimated the spectral distribution with accuracy. Further, seasonal changes in the spectral distribution were well reproduced. The simulation of the module output in Sapporo and Okinawa brought a result that the output in Okinawa is 1.93% larger than in Okinawa. 5 refs., 5 figs., 6 tabs.

  15. Design optimization of ideal non-imaging concentrators for solar collectors by use of yearly insolation model with frequency distribution; Dosu bunpu wo koryoshita nenkan nissha model ni yoru shunetsuyo riso hikessho shukoki no saitekika

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, A. [Tokyo University of Agriculture and Technology, Tokyo (Japan)

    1996-10-27

    Optimization was carried out for the 2D-CPC (compound parabolic concentrator) known as an ideal 2-dimensional non-imaging concentrator for its application to stationary solar heat concentrators. A non-imaging optical system is a system that has an angle for incident light called an acceptance angle, and is treated as an effective tool in the field of solar energy application. Analysis was conducted from the viewpoint of energy and exergy on the presumption of constant temperature operation. For the analysis of constant temperature heat concentration, it needs to be presumed that heat concentrators are in operation only in the presence of insolation that is more than a specified level (critical insolation). When the acceptance angle is fixed for optimization, energy efficiency does not have a peak with respect to the critical probability insolation intensity (in a probability model considering frequency distribution). On the other hand, for the optimization of exergy efficiency, the half-acceptance angle should be within a 35-40{degree} range (agreeing with the optimum angle cost-wise), and the critical probability insolation should be set at 250-300W/m{sup 2} (1/4 of the maximum insolation intensity). The obtained results are low in model dependency and are sufficiently reliable. 14 refs., 4 figs.

  16. Aliasing characteristics of tau-P transform and is application to signal and noise separation; Tau-P henkan no aliasing tokusei to hakei iji wo koryoshita S/N bunri

    Energy Technology Data Exchange (ETDEWEB)

    Kawabuchi, H.; Rokugawa, S.; Matsushima, J.; Ichie, Y. [The University of Tokyo, Tokyo (Japan); Minegishi, M.; Tsuburaya, Y. [Japan National Oil Corp., Tokyo (Japan). Technology Research Center

    1997-05-27

    With respect to the tau-P transform method as a signal and noise (S/N) separation technology used in seismic exploration using the reflection method, a discussion has been given on conditions for the post S/N separation by the tau-P transform to function more effectively. Averaging the energy in performing the tau-P transform makes the wave energy scatter to a certain range. As a result, an aliasing phenomenon appears, in which noise is superimposed on the post-processing record. As a result of the discussion, it was verified that satisfying the two equations of G. Turner is effective in order to reduce the aliasing and maintain the relative amplitude. However, in actual calculation accuracy, waveform change was recognized to some extent, particularly amplification of events in low frequencies, and low restorability in higher frequencies. It was also observed that a method to give the tau-P region a two-dimensional Fourier transform and perform the same processing as an f-k filter can remove aliasing more simply and effectively than the HVF, and improve the S/N ratio maintaining the amplitude at the current level. 5 refs., 13 figs.

  17. On limit state design method considering shear lag phenomenon of corner parts of steel rigid frames. Sendan okure gensho wo koryoshita kosei ramen sumikakubu no genkai jotai sekkeiho ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Nakai, H. (Osaka City University, Osaka (Japan). Faculty of Engineering); Miki, T. (Daido Institute of Technology, Nagoya (Japan)); Hashimoto, Y. (Hanshin Expressway Public Corp., Osaka (Japan))

    1992-10-15

    A remarkable shear lag phenomenon develops in flange plates in beam and column members at corner parts of steel rigid frames. A design method considering the shear lag phenomenon was proposed on rigid frame corner parts to which the beam and column members with box-like cross section are connected perpendicularly. Firstly, mechanisms to transfer forces in the corner parts having been discussed previously and their experimental results were considered, so that the distribution characteristics of sectional forces working on the beam and column members at the corner parts and their vicinities can be explained with help of a simple beam theory. Secondly, a shear lag analysis was carried out on a model to show solutions of added bending moment corresponding to vertical stress. A simple and practicable calculation formula was yielded for a maximum added bending moment at the connecting points of the beam and column members to present a method to check stresses at the corner parts in a limit state. A proposition was made on an ultimate strength checking method based on the yields of flange plates in the beam and column members on webs at the corner parts or their vicinity. 15 refs., 15 figs.

  18. Numerical simulation of hypersonic non-equilibrium wake flow using a higher-resolution method; Goku choonsoku netsu kagaku hiheiko wo koryoshita donto buttai koryu no kokaizodo suchi kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Nagatomo, H.; Yamamoto, S.; Daiguji, H. [Tohoku University, Sendai (Japan). Faculty of Engineering

    1996-08-25

    An object which flies hypersonic speed, such as an aeroassisted orbital transfer vehicle, is affected greatly by not only the bow shock but also the expansion around the shoulder and the recompression of separated flow. Though the experiments to analyze this flow have been performed by some groups recently, there are some difficulties in measuring the flow because of limitations of instrumentation. Both experimental and numerical approaches are necessary to analyze the phenomena. The efficient numerical code which has been developed by the authors for hypersonic thermochemical non-equilibrium flow is applied to simulate the problem. The calculated results of different accuracies in space, the perfect gas and the experimental data are compared. 12 refs., 10 figs., 1 tab.

  19. Calculation of heat balance considering the reflection, refraction of incident ray and salt diffusion on solar pad; Hikari no hansha kussetsu oyobi shio no kakusan wo koryoshita solar pond no netsukeisan

    Energy Technology Data Exchange (ETDEWEB)

    Kanayama, K.; Li, X.; Baba, H.; Endo, N. [Kitami Institute of Technology, (Japan)

    1997-11-25

    In calculating heat balance of solar pond, calculation was made considering things except quality of the incident ray and physical properties of pond water which were conventionally considered. The real optical path length was determined from the reflection ratio of ray on the water surface based on the refraction ratio of pond water and the locus of water transmitted ray in order to calculate a total transmission rate. The rate of absorption of monochromatic lights composing of solar light in their going through the media is different by wavelength, and therefore, calculation was made in each monochromatic light. As to four kinds of salt water solution, NaCl, KCl, MgCl2 and CaCl2, these phenomena seen in solar pond are taken in, and a total transmission rate based on reality can be calculated by the wavelength integration method. Moreover, in the salt gradient layer, there are gradients in both concentration and temperature, and thermal physical values of each layer change. Accordingly, mass transfer and thermal transfer by both gradients were considered at the same time. An analytic solution was introduced which analyzes salt diffusion in the temperature field in the gradient layer and determines the concentration distribution. By these, concentration and physical values of each layer were calculated according to phenomena, and thermal balance of each layer of the solar pond was able to be accurately calculated. 6 refs., 5 figs., 2 tabs.

  20. Study on practical application of a longitudinal hull strength theory considering camber in cross section; Yokodanmen no sori wo koryoshita sentai tate kyodo riron no jitsuyoka ni kansuru kenkyu. 2

    Energy Technology Data Exchange (ETDEWEB)

    Nose, M.; Suzuki, K.; Furuno, H. [Nagasaki Institute of Applied Science, Nagasaki (Japan); Suzuki, K.

    1997-10-01

    Discussions were given on practical application of a stress analyzing method for thin-wall deformed cross-sectional beam considering cross section camber in longitudinal bending. The non-static calculation method described in the previous report can be applied to a box-type cross section having multi-connected cells, bulk cargo transport vessels and container ships with dual hull structure, and oil tankers with dual hull structure of medium size. The calculation method was capable of achieving remarkable enhancement in efficiency over that of conventional calculation methods. The present study is intended to make the method applicable also to multi-connected cross section shapes having more than one longitudinal partitions as used in dual hull VLCC and ULCC. As a result, an expanded non-static calculation system was developed, which has introduced into the conception described in the previous report a new conception of triple point and independent start point members. As a result of applying the method to dual hull bulk cargo transport vessels, container ships, dual hull oil tankers of medium size, VLCC and ULCC, it was verified that the system operated properly. Remarkable efficiency improvement has been made possible as compared with conventional analysis methods applied to individual ships. The system is capable of automatic calculation, and makes possible the practical application of the hull strength theory considering cross section camber. 3 refs., 10 figs., 1 tab.

  1. Improved photoelectrochemical water oxidation by the WO3/CuWO4 composite with a manganese phosphate electrocatalyst.

    Science.gov (United States)

    Nam, Ki Min; Cheon, Eun Ah; Shin, Won Jung; Bard, Allen J

    2015-10-06

    We describe a composite of the n-type semiconductors for the photoelectrochemical oxygen evolution reaction (OER). A simple drop-casting technique of mixed precursors and a one-step annealing process were used in the synthesis of the WO3/CuWO4 composite. The composite showed improved photocurrent for water oxidation compared to either of the two compounds individually. We discuss possible electron-hole separation mechanisms in two semiconductors comprising a primary photon-absorbing semiconductor of CuWO4 with a secondary semiconductor of WO3. When the WO3/CuWO4 composite is simultaneously irradiated, the photogenerated hole from the WO3 valence band transfers to CuWO4, which results in an enhanced charge separation of CuWO4. Furthermore, the OER catalytic activity of manganese phosphate (MnPO) was compared to manganese oxide nanoparticles (Mn2O3) by electrochemical measurements, showing that the manganese phosphate was more efficient for the OER reaction. To investigate the effect of catalysts on semiconductors, manganese phosphate was deposited on the WO3/CuWO4 composite. The result demonstrates the promise of manganese phosphate for improving the photocurrent as well as the stability of the WO3/CuWO4 composite.

  2. Facile Synthesis of Highly Dispersed WO3·H2O and WO3 Nanoplates for Electrocatalytic Hydrogen Evolution

    Directory of Open Access Journals (Sweden)

    Wen-Hui Hu

    2015-01-01

    Full Text Available The highly dispersed WO3·H2O nanoplates have been synthesized by a facile hydrothermal reaction assisted by citrate acid. WO3 nanoplates have been prepared by the calcination of as-prepared WO3·H2O at 450°C. XRD data show that WO3·H2O and WO3 have good crystal structure and high purity. SEM images show that WO3·H2O and WO3 have the uniform nanoplates morphology with the edge length of about 100–150 nm. The selective absorbance of citrate acid with many OH groups onto [010] facet of tungsten oxide precursors can result in the controlled growth of WO3·H2O, thus leading to the good dispersion and small size of WO3·H2O nanoplates. The electrocatalytic activity of WO3·H2O and WO3 for hydrogen evolution reaction (HER has been investigated in detail. The good electrocatalytic activity for HER has been obtained, which may be attributed to the good dispersion and small size of nanoplates. And the growth mechanisms of WO3·H2O and WO3 nanoplates have been discussed.

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

    African Journals Online (AJOL)

    NICO

    reactors. In the beginning, the ion of WO4. 2– is mainly located in the inner surface of the micelle. After adding. CdCl2·2.5H2O solution to the mixture, the Cd2+ ions combine with WO4. 2– to form CdWO4 crystal. The micelle wrapping limit.

  4. Molecular subgrouping of Wolbachia and bacteriophage WO ...

    Indian Academy of Sciences (India)

    2011-12-16

    Dec 16, 2011 ... Kittayapong P. 2011 Infection incidence and relative density of the bacteriophage WO-B in Aedes albopictus mosquitoes from fields in Thailand. Curr. Microbiol. 62, 816–820. Baldo L. and Werren J. H. 2007 Revisiting Wolbachia supergroup typing based on WSP: spurious lineages and discordance with.

  5. 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.

  6. 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.

  7. Transforming Anodized WO3 Films into Visible-Light-Active Bi2WO6 Photoelectrodes by Hydrothermal Treatment.

    Science.gov (United States)

    Ng, Charlene; Iwase, Akihide; Ng, Yun Hau; Amal, Rose

    2012-04-05

    We directly transformed anodized tungsten oxide film (WO3·2H2O) into bismuth tungstate (Bi2WO6) by substituting the intercalated water molecules with [Bi2O2](2+) in a hydrothermal treatment. The resultant Bi2WO6 was readily used as an electrode to produce anodic photocurrent in H2 evolution on the Pt counter electrode observed under visible light irradiation.

  8. Cs2Bi(PO4(WO4

    Directory of Open Access Journals (Sweden)

    Kateryna V. Terebilenko

    2009-09-01

    Full Text Available Dicaesium bismuth(III phosphate(V tungstate(VI, Cs2Bi(PO4(WO4, has been synthesized during complex investigation in a molten pseudo-quaternary Cs2O–Bi2O3–P2O5–WO3 system. It is isotypic with K2Bi(PO4(WO4. The three-dimensional framework is built up from [Bi(PO4(WO4] nets, which are organized by adhesion of [BiPO4] layers and [WO4] tetrahedra above and below of those layers. The interstitial space is occupied by Cs atoms. Bi, W and P atoms lie on crystallographic twofold axes.

  9. Li-driven electrochemical properties of WO3 nanorods

    International Nuclear Information System (INIS)

    Wang Qiang; Wen Zhenhai; Jeong, Yeonseok; Choi, Jiyoung; Lee, Kwangyeol; Li, Jinghong

    2006-01-01

    The Li-driven electrochemical properties of monoclinic WO 3 nanorods, which are prepared by a solution-based colloidal approach, have been studied, and the relationship between the properties and the nanostructures of the material has been established. The electrochemical reactions towards lithium involved in WO 3 nanorods were investigated by means of a galvanostatic method and an impedance technique, and superior characteristics associated with one-dimensional nanostructures were observed. WO 3 nanorods with a high aspect ratio were found to yield an intercalation capacity up to 1.12 Li per formula unit, much higher than the value of 0.78 Li per formula unit for bulk WO 3 . This can be explained on the basis of the unique rod-like structure that effectively enhanced structure stability. The evolution of Li-driven reaction kinetics further illustrated benefits of WO 3 nanorods owing to the increased edge and corner effects

  10. Visible-Near-Infrared-Light-Driven Oxygen Evolution Reaction with Noble-Metal-Free WO2-WO3 Hybrid Nanorods.

    Science.gov (United States)

    Wang, Song Ling; Mak, Yan Lin; Wang, Shijie; Chai, Jianwei; Pan, Feng; Foo, Maw Lin; Chen, Wei; Wu, Kai; Xu, Guo Qin

    2016-12-13

    Understanding and manipulating the one half-reaction of photoinduced hole-oxidation to oxygen are of fundamental importance to design and develop an efficient water-splitting process. To date, extensive studies on oxygen evolution from water splitting have focused on visible-light harvesting. However, capturing low-energy photons for oxygen evolution, such as near-infrared (NIR) light, is challenging and not well-understood. This report presents new insights into photocatalytic water oxidation using visible and NIR light. WO 2 -WO 3 hybrid nanorods were in situ fabricated using a wet-chemistry route. The presence of metallic WO 2 strengthens light absorption and promotes the charge-carrier separation of WO 3 . The efficiency of the oxygen evolution reaction over noble-metal-free WO 2 -WO 3 hybrids was found to be significantly promoted. More importantly, NIR light (≥700 nm) can be effectively trapped to cause the photocatalytic water oxidation reaction. The oxygen evolution rates are even up to around 220 (λ = 700 nm) and 200 (λ = 800 nm) mmol g -1 h -1 . These results demonstrate that the WO 2 -WO 3 material is highly active for water oxidation with low-energy photons and opens new opportunities for multichannel solar energy conversion.

  11. 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 (......2WO4·2H2O). WO3 generates significant interests and is being used in a growing variety of applications. It is therefore important to identify suitable methods of production and better understand its properties. The phase transformation was observed to be initiated between 200 and 300 °C......, and the crystallographic structure of the NRs changed from orthorhombic WO3·H2O to monoclinic WO3. It was rigorously studied by annealing a series of samples ex situ in ambient air up to 800 °C and characterizing them afterward. A temperature-dependent Raman spectroscopy study was performed on tungstite NRs between minus...... 180 and 700 °C. Also, in situ heating experiments in the transmission electron microscope allowed for the direct observation of the phase transformation. Powder X-ray diffraction, electron diffraction, electron energy-loss spectroscopy, and X-ray photoelectron spectroscopy were employed...

  12. Magnetic and structural properties of NaLnMnWO6 and NaLnMgWO6 perovskites

    International Nuclear Information System (INIS)

    King, Graham; Wayman, Lora M.; Woodward, Patrick M.

    2009-01-01

    We have prepared 14 new AA'BB'O 6 perovskites which possess a rock salt ordering of the B-site cations and a layered ordering of the A-site cations. The compositions obtained are NaLnMnWO 6 (Ln=Ce, Pr, Sm, Gd, Dy, and Ho) and NaLnMgWO 6 (Ln=Ce, Pr, Sm, Eu, Gd, Tb, Dy, and Ho). The samples were structurally characterized by powder X-ray diffraction which has revealed metrically tetragonal lattice parameters for compositions with Ln=Ce, Pr and monoclinic symmetry for compositions with smaller lanthanides. Magnetic susceptibility vs. temperature measurements have found that all six NaLnMnWO 6 compounds undergo antiferromagnetic ordering at temperatures between 10 and 13 K. Several compounds show signs of a second magnetic phase transition. One sample, NaPrMnWO 6 , appears to pass through at least three magnetic phase transitions within a narrow temperature range. All eight NaLnMgWO 6 compounds remain paramagnetic down to 2 K revealing that the ordering of the Ln 3+ cations in the NaLnMnWO 6 compounds is induced by the ordering of the Mn 2+ sub-lattice. - Graphical abstract: Evidence for multiple magnetic phase transitions in the A and B-site ordered perovskite NaPrMnWO 6 .

  13. Synthesis and photoelectrochemical properties of CdWO{sub 4} and CdS/CdWO{sub 4} nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Weina [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Zheng, Chunhua [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Department of Mathematics and Physics, Officer College of the Chinese People' s Armed Police Forces, Chengdu 610213 (China); Hua, Hao; Yang, Qi; Chen, Lin [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Xi, Yi, E-mail: yxi6@cqu.edu.cn [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Hu, Chenguo, E-mail: hucg@cqu.edu.cn [Department of Applied Physics, Chongqing University, Chongqing 400044 (China)

    2015-02-01

    Graphical abstract: - Highlights: • A facile CHM strategy is employed for the first time to synthesize CdWO{sub 4} nanowire and nanoflower arrays on cadmium foils. • The photoelectrochemical (PEC) properties are measured on the electrodes made of the CdWO{sub 4} nanowire and nanoflower arrays. • The photocurrent density of the nanowire electrode reaches 0.35 mA/cm{sup 2}, which is 3 times as much as that of the nanoflower electrode. • CdS nanoparticles are deposited on CdWO{sub 4} nanowire arrays to form a CdS/CdWO{sub 4} heterojunction to improve the PEC properties. • The remarkably enhanced photoresponse is achieved on the CdS/CdWO{sub 4} which is twice as much as that on the pure CdWO{sub 4} electrode. - Abstract: A facile composite-salt-mediated strategy is employed for the first time to synthesize CdWO{sub 4} nanowire and nanoflower arrays on cadmium foil substrates. The photoelectrochemical (PEC) properties are measured on the electrodes made of the CdWO{sub 4} nanowire and nanoflower arrays under the simulated sunlight illumination. Both electrodes display high sensitive response and photocurrent stability. The photocurrent density of the nanowire arrays electrode reach 0.35 mA/cm{sup 2}, which is about 3 times as much as that of the nanoflower array electrode. To improve the visible light photocurrent response, CdS nanoparticles are deposited on the CdWO{sub 4} nanowire arrays to form a CdS/CdWO{sub 4} heterojunction. Remarkably enhanced photoresponse is observed on the CdS/CdWO{sub 4} heterostructure and the photocurrent intensity is about twice as much as that of the electrode made of the pure CdWO{sub 4} nanowire arrays. The photoelectric mechanism is also discussed by the crystal structure and morphology characterization, optical band gap and carrier mobility analysis. This work presents a new design of a photoelectrochemical device for possible applications in photoelectrolysis of water and solar cells or highly sensitive light detection.

  14. WO3 Nanoplates Film: Formation and Photocatalytic Oxidation Studies

    Directory of Open Access Journals (Sweden)

    Chin Wei Lai

    2015-01-01

    Full Text Available High surface area of tungsten oxide (WO3 nanoplates films was prepared via simple electrochemical anodization technique by controlling the fluoride content (NH4F in electrolyte. The design and development of WO3-based nanostructure assemblies have gained significant interest in order to maximize specific surface area for harvesting more photons to trigger photocatalytic oxidation reaction. This study aims to determine the optimum content of NH4F in forming WO3 nanoplates on W film with efficient photocatalytic oxidation reaction for organic dye degradation by utilizing our solar energy. The NH4F was found to influence the chemical dissolution and field-assisted dissolution rates, thus modifying the final morphological of WO3-based nanostructure assemblies film. It was found that 0.7 wt% of NH4F is the minimum amount to grow WO3 nanoplates film on W film. The photocatalysis oxidation experimental results showed that WO3 nanoplates film exhibited a maximum degradation of methyl orange dye (≈75% under solar illumination for 5 hours. This behavior was attributed to the better charge carriers transportation and minimizes the recombination losses with specific surface area of nanoplates structure.

  15. 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.

  16. 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.

  17. Quartz roughness affect on WO3 coated QCM

    International Nuclear Information System (INIS)

    Georgieva, V; Raicheva, Z; Grechnikov, A; Gadjanova, V; Atanassov, M; Lazarov, J; Manolov, E

    2010-01-01

    The influence of the initial quartz roughness on the WO 3 -QCM (Quartz Crystal Microbalance) parameters and sorption properties was investigated. Experiments were carried out using AT-cut quartz crystal with different surface roughness obtained after treatment with SiC abrasive having grain size of 3 μm, 7 μm, 14 μm and 20 μm respectively. The QCMs were covered with thin WO 3 films. The equivalent dynamic parameters of the WO 3 - QCM were measured and a correlation with the surface roughness was determined. The equivalent dynamic resistance of the as-created QCM increases from 15.42 Ω to 117 Ω and the quality factor decreases as a result of the roughness changes. The surface morphology was observed by a Scanning Electron Microscopy (SEM), which showed higher increase of the WO 3 surface roughness compared to those of the initial quartz surface. The cross-section profiles of the investigated structures show different overlay of Au-electrodes. The sorption properties of WO 3 -QCM system to NH 3 were studied in the range from 10 ppm to 1000 ppm. The response and recovering times were determined. The experimental results show an increase of the sorption ability with the increase of the initial quartz roughness. By increasing the roughness the mass-loading is improved.

  18. 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.

  19. The chemistry of ZnWO4 nanoparticle formation

    DEFF Research Database (Denmark)

    Bøjesen, Espen Drath; Jensen, Kirsten Marie Ørnsbjerg; Tyrsted, Christoffer

    2016-01-01

    The need for a change away from classical nucleation and growth models for the description of nanoparticle formation is highlighted. By the use of in situ total X-ray scattering experiments the transformation of an aqueous polyoxometalate precursor mixture to crystalline ZnWO4 nanoparticles under...... hydrothermal conditions was followed. The precursor solution is shown to consist of specific Tourné-type sandwich complexes. The formation of pristine ZnWO4 within seconds is understood on the basis of local restructuring and three-dimensional reordering preceding the emergence of long range order in ZnWO4...... nanoparticles. An observed temperature dependent trend in defect concentration can be rationalized based on the proposed formation mechanism. Following nucleation the individual crystallites were found to grow into prolate morphology with elongation along the unit cell c-direction. Extensive electron microscopy...

  20. Reflectivity modulation with LixWO3 thin films

    International Nuclear Information System (INIS)

    Arntz, F.O.; Berera, G.; Goldner, R.B; Haas, T.E.; Moprel, B.

    1990-01-01

    One potentially improtant application for electrochromic (and other solid-state ionic)thin films is as the electrochemically-controlled reflectivity-modulated layer in smart window glass (or smart windows). In principle, smart windows can be operated in either of two modes: absorptivity modulation or reflectivity modulation. The feasibility of utilizing polycrystalline (pc) tungsten bronze films, M x WO 3 (M = H, Li), to obtain spectrally selective reflectivity modulation has been previously demonstrated. The question addressed in this paper is to determine the upper bound for the near infrared reflectivity modulation of pc-Li x WO 3 films

  1. 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.

  2. 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.

  3. Surface oxygen vacancies on WO{sub 3} contributed to enhanced photothermo-synergistic effect

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yingying; Wang, Changhua; Zheng, Han; Wan, Fangxu; Yu, Fei; Zhang, Xintong, E-mail: xtzhang@nenu.edu.cn; Liu, Yichun

    2017-01-01

    Graphical abstract: WO{sub 3−x} acts as efficient and stable photothermocatalyst for detoxification of gaseous acetaldehyde. - Highlights: • WO{sub 3} was annealed under air and hydrogen atomsphere. • Phase transition from WO{sub 3} to WO{sub 2.72} to WO{sub 2} was observed after hydrogen treatment. • WO{sub 3−x} with optimized degree of oxygen deficiency displayed significant photothermocatalytic activity against degradation of acetaldehyde. • Mechanism operating in photocatalytic and thermal effects is discussed. - Abstract: Photothermooxidation has demonstrated a high efficiency in the removal of volatile organic compounds in air. Among photothermocatalysts, attention is presently focused on composites of noble metal/metal oxide or metal oxide/metal oxide. Instead, in this work, we present a case of single oxide WO{sub 3} subjected to hydrogen treatment as photothermocatalyst. With the increase of hydrogen treatment temperature, the color of WO{sub 3} changes from yellow to blue to dark blue and a phase transition from WO{sub 3} to WO{sub 2.72} to WO{sub 2} is accompanied, suggesting an increase of concentration of oxygen vacancy. Photothermocatalytic test against degradation of gaseous acetaldehyde at 60 °C under UV light shows that WO{sub 3−x} sample with low concentration of oxygen vacancy displays the most significant synergetic effect between photocatalysis and thermocatalysis. Its photothermocatalytic activity in terms of CO{sub 2} evolution rate is 5.2 times higher than that of photocatalytic activity. However, WO{sub 3}–WO{sub 2.72} and WO{sub 2} with high degree of oxygen deficiency show insignificant synergetic effect between photocatalysis and thermocatalysis. The reason for the different synergistic effect over above samples is believed to lie in balance between decreased activation energy of lattice oxygen and recombination of photogenerated electrons and holes induced by oxygen deficiency.

  4. Influence on driver fatigue of vertical vibrations over long distances. Assessment in terms of stress hormones; Driver no unten hiro ni okeru joge shindo no eikyo. Stress hormone wo shiyo to shite

    Energy Technology Data Exchange (ETDEWEB)

    Taguchi, T.; Inagaki, H. [Toyota Central Research and Development Labs., Inc., Aichi (Japan)

    1998-05-01

    Driving tests are conducted to obtain some indexes that describe the cumulative effect of the sense of tiredness. The heart rate, Mayer wave related sinus arrhythmia, respiratory sinus arrhythmia, urinary adrenaline, noradrenaline, and cortisol in saliva are tested. Adrenaline and Mayer wave related sinus arrhythmia are ultimately named in view of their correlation with tiredness. It is believed that tiredness is attributable to two factors, which are increase in mental stress and decrease in vigilance. An excitation test is then conducted using a motion simulator. Upon application of 4Hz vibrations (equivalent to the chest section resonance frequency), adrenaline increases sharply, and then decreases sharply upon termination of excitation. Upon application of 1.6Hz vibrations (equivalent to the head section resonance frequency), adrenaline increases but not sharply, and the elevated level is sustained for some time after excitation. Driving tests are next conducted using a vehicle with its suspension fixed and another with 1-2Hz vibrations reduced. Rise in the adrenaline level is found inhibited aboard the latter. No difference is detected in terms of Mayer wave related sinus arrhythmia between the two vehicles. 4 refs., 7 figs., 4 tabs.

  5. Effect of pore water pressure on P-wave velocity in water-filled sands with partial air saturation; Fukanzen howa jotai no suna shiryo wo denpasuru P ha sokudo ni oyobosu kangeki suiatsu no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Kanema, T. [Chishitsu-Keisoku Co. Ltd., Tokyo (Japan)

    1997-10-22

    With an objective to elucidate change in velocity of elastic waves in association with water pressure increase in a sand bed below the groundwater level in a shallow portion of the ground, a measurement experiment was carried out on P-wave velocity in sand samples with partial air saturation. The experiment has used fine sand having an equivalent coefficient of 2.40, a soil particle density of 2.68 g/cm {sup 3} or 60%, and a grain size of 0.36 mm. Inside the water-filled sand sample, two accelerometers were embedded 20 cm apart from each other as vibration receivers. An electromagnetic hammer for P-wave was used as the vibration source. In the experiment, measurement was carried out on the P-wave velocity in association with increase in pore water pressure by applying water pressure afresh to the water-filled sample. As a result of the experiment, the following matters were disclosed: the P-wave velocity increases as the pore water pressure was increased, and a phenomenon was recognized that the dominant frequency changes into high frequency; the degree of increase in the P-wave velocity varies depending on initial saturation of the sample; and bubbles in the pore fluid have their volume decreased due to compression resulted from increased pore water pressure and dissolution of air into the pore water. 6 refs., 11 figs.

  6. Transparency and radiation hardness of Cherenkov crystals NaBi(WO4)2:Sc

    International Nuclear Information System (INIS)

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

    2001-01-01

    The effects of doping the Cherenkov crystal NaBi(WO 4 ) 2 with Sc ions on the optical properties and radiation hardness of this crystal have been studied. The radiation hardness of NaBi(WO 4 ) 2 :Sc is about 3 times higher than that of undoped NaBi(WO 4 ) 2 . 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 4 ) 2 :Sc crystals compared with undoped NaBi(WO 4 ) 2 of approximately 15%

  7. HRTEM Microstructural Characterization of ?-WO3 Thin Films Deposited by Reactive RF Magnetron Sputtering

    OpenAIRE

    Faudoa-Arzate, A.; Arteaga-Dur?n, A.; Saenz-Hern?ndez, R.J.; Botello-Zubiate, M.E.; Realyvazquez-Guevara, P.R.; Matutes-Aquino, J.A.

    2017-01-01

    Though tungsten trioxide (WO3) in bulk, nanosphere, and thin film samples has been extensively studied, few studies have been dedicated to the crystallographic structure of WO3 thin films. In this work, the evolution from amorphous WO3 thin films to crystalline WO3 thin films is discussed. WO3 thin films were fabricated on silicon substrates (Si/SiO2) by RF reactive magnetron sputtering. Once a thin film was deposited, two successive annealing treatments were made: an initial annealing at 400...

  8. 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.

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

    Indian Academy of Sciences (India)

    Dynamic and static light scattering experiments have been performed at various molar ratios () of water to AOT and temperatures on water-in-oil (W/O) microemulsions dispersed in n-heptane, n-octane, and n-nonane. Size and shape fluctuations of microemulsion droplets are determined with very high precision because ...

  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

    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. Electrochromic properties of electrodeposited tungsten oxide (WO3) thin film

    Science.gov (United States)

    Dalavi, D. S.; Kalagi, S. S.; Mali, S. S.; More, A. J.; Patil, R. S.; Patil, P. S.

    2012-06-01

    In this work, we report on a potentiostatic electrochemical procedure employing an ethanolic solution of peroxotungstic acid yielded tungsten oxide (WO3) films specifically for transmissive electrochromic devices (ECDs) such as "smart windows". WO3 film was confirmed from the binding energy determination by X-ray photoelectron spectroscopic studies. The diffusion coefficient during intercalation and deintercalation was found to be 2.59×10-10 and 2.40×10-10 cm2/C. Electrodeposited WO3 produce high color/bleach transmittance difference up to 74% at 630 nm. On reduction of WO3, the CIELAB 1931 2% color space coordinates show the transition from colorless to the deep blue state (L=95.18, a=2.12, b=0.3138, and L=57.78, a=-21.79, b=0.244) with steady decrease in relative luminance. The highest coloration efficiency (CE) of 92 cm2/C and good response time of 10.28 for coloration (reduction) and 3.2 s for bleaching (oxidation) was observed with an excellent reversibility of 89%.

  13. WO/sub 3/ thin films for practical electrochromic windows

    International Nuclear Information System (INIS)

    Goldner, R.B.; Wong, K.; Foley, G.; Norton, P.; Wamboldt, L.; Seward, G.; Haas, T.; Chapman, R.

    1986-01-01

    This paper shows that practical spectrally-selective transmittance modulation can be achieved with thin (50-100nm) WO/sub 3/ films, and therefore such films should be useful for fabricating electrochromic windows. The transmittance and reflectance modulation results are compared with theoretical predictions. The results indicate an excess intraband absorptance, which is attributed to free electron scattering arising from extended defects

  14. 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 ...

  15. Morphological and structural modulation of PbWO{sub 4} crystals directed by dextrans

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jinhu; Lu Conghua; Su Hong; Ma Jiming; Cheng Humin; Qi Limin [Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Stable and Unstable Species, College of Chemistry, Peking University, Beijing 100871 (China)

    2008-01-23

    A facile, dextran-directed solution route for the morphology- and structure-controlled synthesis of PbWO{sub 4} crystals, such as monoclinic raspite PbWO{sub 4} nanobelts and tetragonal stolzite PbWO{sub 4} crystals with penniform and wheat-ear-like morphologies, has been demonstrated. Three differently charged dextrans were employed for the PbWO{sub 4} crystallization and they turned out to be very effective in the morphological and structural modulation of PbWO{sub 4} crystals, as evidenced by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD) and Raman spectroscopy characterizations. In particular, novel monoclinic raspite PbWO{sub 4} nanobelts were produced under the direction of anionic dextran with a suitable concentration, probably due to the specific interactions between SO{sub 4}{sup 2-} groups from anionic dextran molecules and Pb{sup 2+} ions from PbWO{sub 4} crystals. To the best of our knowledge, this is the first synthesis of monoclinic raspite PbWO{sub 4} in the laboratory, which usually exists as a natural crystal. In addition, the photoluminescence properties of the obtained PbWO{sub 4} crystals with different morphologies and crystal structures have been characterized and discussed, which provides useful information for the fundamental investigation and potential application of PbWO{sub 4} crystals.

  16. Acetone sensing of multi-networked WO3-NiO core-shell nanorod sensors

    Science.gov (United States)

    Choi, Seungbok; Lee, Jae Kyung; Lee, Woo Seok; Lee, Chongmu; Lee, Wan In

    2017-10-01

    WO3-NiO core-shell nanorods were synthesized by thermal evaporation of a mixture of WO3 and graphite powders and immersion of the synthesized WO3 nanorods in an 20 mM of nickel(II) acetate tetrahydrate (Ni(OCOCH3)2·4H2O) solution followed by UV irradiation and annealing. Subsequently, multi-networked nanorod sensors were fabricated by connecting these nanostructures with electrodes. The sensing properties of pristine WO3 nanorod and WO3-NiO core-shell nanorod sensors toward acetone were examined. Subsequently, multi-networked nanorod sensors were fabricated by connecting these nanostructures with electrodes. The WO3-NiO core-shell nanorod sensor exhibited a stronger response to acetone gas and shorter response/recovery times than the pristine WO3 nanorod sensor. The pristine WO3 nanorods showed responses of approximately 1.36 to 200 ppm of CH3COCH3 at 300 °C. On the other hand, the WO3-NiO core-shell nanorods showed responses of 4.4 to the same concentration of CH3COCH3 at the same temperature. The core-shell nanorods exhibited response and recovery times of 51 s and 59 s, respectively for 200 ppm of CH3COCH3. On the other hand, the pristine WO3 nanorods exhibited response and recovery times of 51 s and 59 s, respectively, for the same concentration of CH3COCH3. NiO coating enhanced the selectivity of the WO3 nanorods for acetone as well as the sensitivity of the WO3 nanorods. The underlying mechanism of the enhanced response of the WO3-NiO core-shell nanorod sensor is also discussed in detail.

  17. 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.

  18. 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.

  19. 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.)

  20. NixWO2.72 nanorods as an efficient electrocatalyst for oxygen evolution reaction

    OpenAIRE

    Zheng Xi; Adriana Mendoza-Garcia; Huiyuan Zhu; MiaoFang Chi; Dong Su; Daniel P. Erdosy; Junrui Li; Shouheng Sun

    2017-01-01

    NixWO2.72 nanorods (NRs) are synthesized by a one-pot reaction of Ni(acac)2 and WCl4. In the rod structure, Ni(II) intercalates in the defective perovskite-type WO2.72 and is stabilized. The NixWO2.72 NRs show the x-dependent electrocatalysis for the oxygen evolution reaction (OER) in 0.1 M KOH with Ni0.78WO2.72 being the most efficient, even outperforming the commercial Ir-catalyst. The synthesis is not limited to NixWO2.72 but can be extended to MxWO2.72 (M = Co, Fe) as well, providing a ne...

  1. Photocatalytic Removal of Microcystin-LR by Advanced WO3-Based Nanoparticles under Simulated Solar Light

    Science.gov (United States)

    Zhao, Chao; Li, Dawei; Feng, Chuanping; Zhang, Zhenya; Sugiura, Norio; Yang, Yingnan

    2015-01-01

    A series of advanced WO3-based photocatalysts including CuO/WO3, Pd/WO3, and Pt/WO3 were synthesized for the photocatalytic removal of microcystin-LR (MC-LR) under simulated solar light. In the present study, Pt/WO3 exhibited the best performance for the photocatalytic degradation of MC-LR. The MC-LR degradation can be described by pseudo-first-order kinetic model. Chloride ion (Cl−) with proper concentration could enhance the MC-LR degradation. The presence of metal cations (Cu2+ and Fe3+) improved the photocatalytic degradation of MC-LR. This study suggests that Pt/WO3 photocatalytic oxidation under solar light is a promising option for the purification of water containing MC-LR. PMID:25884038

  2. 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.

  3. HRTEM Microstructural Characterization of β-WO3 Thin Films Deposited by Reactive RF Magnetron Sputtering.

    Science.gov (United States)

    Faudoa-Arzate, A; Arteaga-Durán, A; Saenz-Hernández, R J; Botello-Zubiate, M E; Realyvazquez-Guevara, P R; Matutes-Aquino, J A

    2017-02-17

    Though tungsten trioxide (WO3) in bulk, nanosphere, and thin film samples has been extensively studied, few studies have been dedicated to the crystallographic structure of WO3 thin films. In this work, the evolution from amorphous WO3 thin films to crystalline WO3 thin films is discussed. WO3 thin films were fabricated on silicon substrates (Si/SiO2) by RF reactive magnetron sputtering. Once a thin film was deposited, two successive annealing treatments were made: an initial annealing at 400 °C for 6 h was followed by a second annealing at 350 °C for 1 h. Film characterization was carried out by X-ray diffraction (XRD), high-resolution electron transmission microscopy (HRTEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM) techniques. The β-WO3 final phase grew in form of columnar crystals and its growth plane was determined by HRTEM.

  4. HRTEM Microstructural Characterization of β-WO3 Thin Films Deposited by Reactive RF Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    A. Faudoa-Arzate

    2017-02-01

    Full Text Available Though tungsten trioxide (WO3 in bulk, nanosphere, and thin film samples has been extensively studied, few studies have been dedicated to the crystallographic structure of WO3 thin films. In this work, the evolution from amorphous WO3 thin films to crystalline WO3 thin films is discussed. WO3 thin films were fabricated on silicon substrates (Si/SiO2 by RF reactive magnetron sputtering. Once a thin film was deposited, two successive annealing treatments were made: an initial annealing at 400 °C for 6 h was followed by a second annealing at 350 °C for 1 h. Film characterization was carried out by X-ray diffraction (XRD, high-resolution electron transmission microscopy (HRTEM, scanning electron microscopy (SEM, and atomic force microscopy (AFM techniques. The β-WO3 final phase grew in form of columnar crystals and its growth plane was determined by HRTEM.

  5. Preparation of WO3 Nanoparticles Using Cetyl Trimethyl Ammonium Bromide Supermolecular Template

    OpenAIRE

    Nilofar Asim; S. Radiman; M. A.B. Yarmo

    2009-01-01

    Problem statement: WO3 is one of the most interested metal oxides because of its application as catalysts, sensors, electrochromic devices, ceramic, solar cell, pigments and so on. More investigation is needed to find the good and low cost method for preparation of WO3 nanoparticles with uniform morphology and narrow distribution using a surfactant mediated method. Approach: In this study, the synthesis of WO3 nanoparticles was accomplished using a cationic surfactant (cetyl trimethyl ammoniu...

  6. 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.

  7. 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}.

  8. CTAB-assisted ultrasonic synthesis, characterization and photocatalytic properties of WO3

    International Nuclear Information System (INIS)

    Sánchez-Martínez, D.; Gomez-Solis, C.; Torres-Martinez, Leticia M.

    2015-01-01

    Highlights: • WO 3 2D nanostructures were synthesized by ultrasound method assisted with CTAB. • WO 3 morphology was mainly of rectangular nanoplates with a thickness of ∼50 nm. • The highest surface area value of WO 3 was obtained to lowest concentration of CTAB. • WO 3 activity was attributed to morphology, surface area and the addition of CTAB. • WO 3 nanoplates were able to causing almost complete mineralization of rhB and IC. - Abstract: WO 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 3 was confirmed by X-ray powder diffraction (XRD). The characterization of the WO 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 g ) of the WO 3 samples. The photocatalytic activity of the WO 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 3 . Photodegradation of rhB and IC were followed by means of UV–vis absorption spectra. The mineralization degree of organic dyes by WO 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

  9. Acoustic properties of monocrystals Na Bi(WO4)2

    International Nuclear Information System (INIS)

    Khusravbekov, L.; Rakhimov, I.K.; Salakhutdinov, M.I.; Kholov, A.

    2001-01-01

    Present article is devoted to acoustic properties of monocrystals Na Bi(WO 4 ) 2 . The method of growing of large, homogeneous, defect-free monocrystals of Na Bi(WO 4 ) 2 compound was elaborated. The measurement of propagation velocity and ultrasound absorption coefficient in Na Bi(WO 4 ) 2 at temperature range 30-100 deg C on operating frequency 35 MHz was conducted by means of phase-interference method.

  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. Phase diagram of NaFe(WO{sub 4}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, Yvonne; Orbe, Stephanie; Heyer, Oliver; Lorenz, Thomas [II. Physikalisches Institut, University of Cologne (Germany); Jodlauk, Sven; Albiez, Sebastian; Becker, Petra; Bohaty, Ladislav [Institut fuer Kristallographie, University of Cologne (Germany)

    2011-07-01

    Multiferroic materials show simultaneous ferroelectric and magnetic order, which are strongly coupled to each other. A well-known model system is MnWO{sub 4} with only one kind of magnetic ions and three magnetically ordered phases below {proportional_to}13 K. Here, the multiferroic behavior of one of these phases arises from an incommensurate spin spiral structure. Much less is known about the double tungstate NaFe(WO{sub 4}){sub 2}, which has a structure closely related to MnWO{sub 4}. While in MnWO{sub 4} sheets parallel (100) of MnO{sub 6} zig-zag chains alternate with similar sheets of WO{sub 6}, in NaFe(WO{sub 4}){sub 2} an alternating sheet sequence FeO{sub 6}-WO{sub 6}-NaO{sub 6}-WO{sub 6} - is found. Consequently, the a lattice parameter is doubled and the magnetic subsystem is diluted. The ordering temperature in NaFe(WO{sub 4}){sub 2} is reduced to T{sub N}{approx} 4 K. The magnetic structure in zero magnetic field is reported to be collinear antiferromagnetic, but the H-T phase diagram has not been published so far. Here, we present a detailed study of this phase diagram obtained by high-resolution thermal expansion and magnetostriction measurements. We find pronounced hysteresis effects, which resemble those observed in other multiferroic materials.

  12. Synthesis and photocatalytic properties of α-ZnWO4 nanocrystals in tungsten zinc borate glasses

    Directory of Open Access Journals (Sweden)

    Tatsuya Ida

    2014-09-01

    Full Text Available Tungsten oxide (WO3-containing glasses of WO3–ZnO–B2O3 were prepared using a conventional melt quenching method, and α-ZnWO4 nanocrystals were synthesized through the crystallization of glasses. A glass with the composition of 20WO3–50ZnO–30B2O3 showed the bulk crystallization of α-ZnWO4 nanocrystals with a diameter of ∼10 nm. Broad and asymmetric emission peaks were observed at the wavelength of λ ∼ 475 nm, i.e., blue emissions, in the photoluminescence spectra for the samples with α-ZnWO4 nanocrystals. From the degradation of the intensity of optical absorption under ultraviolet light (λ = 254 nm irradiations for the solution consisting of crystallized particles with α-ZnWO4 nanocrystals and methylene blue, it was clarified that α-ZnWO4 nanocrystals formed have photocatalytic activities. The formation of α-ZnWO4 nanocrystals is discussed from the viewpoint of the glass-forming tendency.

  13. Preparation of WO3 thin film by successive dip coating for electrochromic and photoelectrochromic devices

    International Nuclear Information System (INIS)

    Park, Jae Hyuk; Kang, Jin Soo; Kim, Jin; Lee, Kyung Jae; Sung, Yung Eun; Cha, In Young

    2015-01-01

    Here we report the superiority of WO 3 thin films prepared by successive dip coating in electrochromic devices. Dip coatings were done on transparent conducting oxide substrates in the WO 3 precursor solution a number of times without drying in between the coating steps. This process enabled the fabrication of WO 3 films with optimum thickness and large roughness, which led to enhanced performance when they were employed as the electrode in electrochromic devices. We made a further observation by applying these electrodes in photoelectrochromic devices and verified the excellent properties of the successively dip-coated WO 3 films

  14. Phase relations and chemical vapor transport of hexagonal indium tungsten bronze InxWO3

    International Nuclear Information System (INIS)

    Steiner, Udo

    2014-01-01

    Highlights: • Phase relations of hexagonal bronze In x WO 3 with neighboring phases. • Chemical vapor transport experiments using NH 4 Cl as transport agent. • Single crystals of In x WO 3 up to a few mm in size were prepared. • Selective synthesis of crystals of the indium poor and indium rich phase boundary. - Abstract: Phase pure powder samples of hexagonal indium tungsten bronze In x WO 3 (x = 0.25–0.35) were synthesized by solid state reaction at 1173 K. The phase relations of In x WO 3 with neighboring binary and ternary phases were determined in the phase diagram In–W–O. Systematic chemical vapor transport experiments were carried out on source materials with compositions corresponding to miscellaneous two-phase and three-phase regions using NH 4 X (X = Cl, Br, I) as transport agent. Crystals of hexagonal indium tungsten bronze were deposited beside In 2 W 3 O 12 with composition corresponding to the indium poor phase boundary and dimensions up to a few mm in a temperature gradient 1173 K → 1073 K starting from ternary mixtures In x WO 3 /In 2 W 3 O 12 /In 0.02 WO 3 . Sole deposition of In x WO 3 single crystals with composition x ≈ 0.33 was observed from ternary mixtures In x WO 3 /W 18 O 49 /WO 2 with a migration rate of about 0.5 mg/h (transport agent NH 4 Cl)

  15. 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.

  16. CONTINUOUS-WAVE MICROCHIP LASER GENERATION OF Tm:KLu(WO42 AND Tm:KY(WO42 CRYSTALS

    Directory of Open Access Journals (Sweden)

    O. P. Dernovich

    2016-01-01

    Full Text Available Diode-pumped solid-state lasers are attractive for a variety of practical applications in many fields of human activity due to their high efficiency, compactness, and long durability. For applications in remote sensing lasers emitting in the spectral range of about 2 microns are required. Materials doped with trivalent thulium ions are promising active media emitting in this spectral range. Potassium rare-earth tungstates are attractive materials among Tm-doped crystals due to their suitable characteristics, such as high values of absorption and stimulated emission cross sections, incignificant concentration quenching of luminescence, well-proven technology of the high quality crystals growth. The purpose of this paper was to compare lasing properties of lasers based on potassium lutetium and potassium yttrium tungstate crystals doped with thulium ions in continuous-wave regime. Experiments were carried out with a diode pumping in microchip cavity configuration. The maximum power of laser radiation at 1947 nm of 1010 mW was obtained with Tm:KY(WO42 crystal with the slope efficiency with respect to the absorbed pump power of 51 %. When Tm:KLu(WO42 crystal was utilized an output power of 910 mW at 1968 nm wavelength with the slope efficiency of 38 % was obtained. With Tm:KLu(WO42 laser a tuning range over 160 nm range was realized with a prism inserted into the laser cavity. 

  17. Preparation and emission properties of NaBi(WO4)2 and NaBi(WO4)2:Ce single crystals

    International Nuclear Information System (INIS)

    Nitsch, K.; Nikl, M.; Barta, C.; Triska, A.

    1990-01-01

    The preparation of pure and Ce 3+ -doped NaBi(WO 4 ) 2 single crystals (NBW) and the determination of their basic transmission and emission properties including time-resolved measurements are described. The decay of NBW emission is obviously non-exponential. It can be concluded that emission arises at regular sites of the crystal lattice and is connected with electronic transitions from Bi 3+ to the WO 4 2- group and/or excitation of the WO 4 2- group itself. It is not possible to excite Ce 3+ ions directly

  18. Report on survey in fiscal 2000 on the survey and research on technology to integrate artificial bone system with living organism, taking individual difference into account; 2000 nendo kotaisa wo koryoshita jinkokotsu system no seitai tekigoka gijutsu ni kansuru chosa kenkyu hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    Survey and research have been performed on artificial bones as to the bone growth and bone absorption mechanism, nature demanded in artificial bones, and ideal concept of artificial bones. As a result of the survey, the following matters were made clear: Ti alloy draws high attention as the artificial bone material; and up-to-date research is being made to promote fusion of the Ti alloy bone with natural bones by putting apatite covering on the Ti alloy bone by means of chemical treatment, wherein porous layers are produced on the surface that do not form inclination from a dense bone to a sponging bone, or from high density to low density, but produce the reverse inclination, as in the cross section structure of natural bones. Reports have been given from the dentistry, oral surgery, plastic surgery, and orthopedic surgery on the followings: a fact that magnesium affects greatly the stimulation of osteoblasts; a case where absorption of the mandibular bone has been created clinically due to Ti-made mini-plate; and a case where even Ti has been eluted into soft tissues. Artificial bones made of magnesium structure is being studied as one of the solutions thereof. (NEDO)

  19. Method for estimation of the output electric power of PV module with considering environmental factors. Method for estimation of output using I-V curves; Kankyo inshi wo koryoshita taiyo denchi module no shutsuryoku keisanho. I-V tokusei curve ni yoru keisan

    Energy Technology Data Exchange (ETDEWEB)

    Yamagami, Y.; Tani, T. [Science University of Tokyo, Tokyo (Japan)

    1996-10-27

    Based on the basic quality equation of photovoltaic (PV) cell, a quality equation of PV module has been constructed by considering the spectral distribution of solar radiation and its intensity. A calculation method has been also proposed for determining the output from current-voltage (I-V) curves. Effectiveness of this method was examined by comparing calculated results and observed results. Amorphous Si (a-Si) and polycrystal Si PV modules were examined. By considering the environmental factors, differences of the annual output between the calculated and observed values were reduced from 2.50% to 0.95% for the a-Si PV module, and from 2.52% to 1.24% for the polycrystal Si PV module, which resulted in the reduction more than 50%. For the a-Si PV module, the environmental factor most greatly affecting the annual output was the spectral distribution of solar radiation, which was 3.86 times as large as the cell temperature, and 1.04 times as large as the intensity of solar radiation. For the polycrystal PV module, the environmental factor most greatly affecting the annual output was the cell temperature, which was 7.05 times as large as the spectral distribution of solar radiation, and 1.74 times as large as the intensity of solar radiation. 6 refs., 4 figs., 1 tab.

  20. Consideration on the dynamic behavior and the structural design of large scale floating structure. 2nd Report. Stability of elastic structure and design of elastic response; Choogata futai no kozo kyodo oyobi kozo sekkei ni kansuru kosatsu. 2. Dansei henkei wo koryoshita fukugensei oyobi kozo oto no sekkei

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, H.; Yoshida, K. [The University of Tokyo, Tokyo (Japan)

    1996-12-31

    A policy of improving a very large floating body was planned based on its dynamic characteristics, and a proposal was made thereon. Furthermore, discussions were given on stability that considers effect of elastic deformation required when a structure is mounted on a floating body. With respect to a structural design of a very large floating body in which elastic response is governing, and upon modeling the very large floating body into an aeolotropic plate on an elastic supporting floor, it was shown that the existing range of natural vibration speed in the elastic response is in higher range than the natural vibration speed of heave. It was also indicated that the peak height of response to waves in resonance is inversely proportional to wave frequency, and furthermore, degree of flowing in of vibration energy during the resonance is determined by an inner product of spatial vibration patterns of wave force and the excited mode shape. A proposal was made on a floating body improved of excessive response in the floating body edges by changing the characteristics of the floating body edges. In addition, discussions were given on stability that considers elastic deformation of a floating body that becomes necessary when a structure, such as a building, is built on a very large floating body. 9 refs., 9 figs., 3 tabs.

  1. Performance evaluation of solar heating system with thermal core type soil heat storage. Part 5. Performance prediction and evaluation of the system considered of the weather condition; Taiyonetsu riyo netsu kakushiki dojo chikunetsu system no seino hyoka. 5. Kisho joken wo koryoshita system no seino yosoku to hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, N. [Nishimatsu Construction Co. Ltd., Tokyo (Japan); Nakajima, Y. [Kogakuin University, Tokyo (Japan)

    1997-11-25

    The paper studied a solar heating system with thermal core type soil heat storage (combining a thermal core composing of a water tank and an underground pebble tank and the soil around the heat storage tank and also using solar energy). Solar energy is stored by temperature level in the high temperature water tank, the low temperature pebble heat storage tank and the soil around the heat storage tank. Heat is recovered according to temperature as direct ventilation space heating (utilization of pebble tank air), floor heating (utilization of hot water of the heat storage water tank) and heat pump heat source (utilization of pebble tank air). A study was made of performance and regional effectiveness of the system under different weather conditions. A study was also made of effects of the water tank for short term heat storage by changing the water volume. Using the same structure, etc. for the system, the system was evaluated using weather data of Sapporo, Tokyo and Kagoshima. In terms of efficiency of the system, the system structure was found to be most suitable for weather conditions in Tokyo. However, the air heat source heat pump which cannot be usually used in the cold area has come to be used. Such effect except efficiency is also considered, and the amount of performance to be targeted in each region changes. 2 refs., 14 figs., 1 tab.

  2. Ionization current in N2 gas. 11. Three dimensional analysis for loss processes of metastable particles affected by the reflection at the boundary; N2 gas chu ni okeru denri denryu. 11. Kyokai deno hansha wo koryoshita jun`antei reiki ryushi sonshitsu katei no sanjigen kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, S.; Ito, H.; Sekizawa, H.; Ikuta, N. [Chiba Institute of Technology, Chiba (Japan)

    1998-10-01

    Loss processes of the nitrogen metastable molecule N2(A{sup 3}{Sigma}u{sup +}) in plane parallel electrodes have been investigated by us previously by solving the diffusion equation. Our procedure is based on an analysis using the third kind of boundary condition which can take account of finite values for the density of N2(A{sup 3}{Sigma}u{sup +}) at the electrode surfaces. The values of the effective lifetime of N2(A{sup 3}{Sigma}u{sup +}) calculated from this analysis were reasonably consistent with our experiments. This paper describes the behavior of the effective lifetimes of N2(A{sup 3}{Sigma}u{sup +}) in a cylindrical cavity. The analytical treatment of the diffusion equation for N2(A{sup 3}{Sigma}u{sup +}) proposed by us is extended to the three dimensional space. We report the nature of the effective lifetimes of metastable molecule in the cylindrical cavity systematically. 16 refs., 9 figs.

  3. Annual cycle solar energy utilization with seasonal storage. Part 7. Examination on design and control of the system partially recovering exhaust heat of heat pump; Kisetsukan chikunetsu ni yoru nenkan cycle taiyo energy riyo system ni kansuru kenkyu. 7. Bubuntekina hainetsu kaishu wo koryoshita baai no sekkei seigyoho no kento

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, H.; Okumiya, M. [Nagoya University, Nagoya (Japan)

    1996-10-27

    The capacity and performance of the existing system that recovers the overall heating and cooling exhaust heat completely into a seasonal storage tank and the system that discharges the exhaust heat slightly to the outside and recovers it partially were compared and investigated. The system uses a central single-duct discharge system as an air-conditioning system. A heat pump and a flat-plate solar collector installed on the roof of a building are used as the heat source. The seasonal storage tank in the ground just under the building is a cylindrical water tank of 5 m deep with the concrete used as body. The upper surface of a storage tank is heat-insulated by a stylo-platform of 200 mm, and the lower side surface by a stylo-platform of 100 mm. Calculation when the difference in temperature used in a seasonal storage tank is set to 35{degree}C and 25{degree}C was performed for the system that has two control methods. The overall exhaust heat recovery system is almost the same in energy performance as the partial exhaust heat recovery system. The partial exhaust heat recovery system is more advantageous on the economic side. 4 refs., 6 figs., 3 tabs.

  4. 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.

  5. WoPeD - A "Proof-of-Concept" Platform for Experimental BPM Research Projects

    DEFF Research Database (Denmark)

    Freytag, Thomas; Allgaier, Philip; Burattin, Andrea

    2017-01-01

    WoPeD (Workflow Petrinet Designer) is an open-source, Java-based software product supporting the creation, simulation and analysis of business process models. Over the years, WoPeD has become a widely-used tool in the academic sector, primarily known and used for teaching purposes. To some extent...

  6. Facile synthesis of layered MnWO{sub 4}/reduced graphene oxide for supercapacitor application

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Jianhua; Shen, Jianfeng, E-mail: jfshen@fudan.edu.cn; Li, Na; Ye, Mingxin, E-mail: mxye@fudan.edu.cn

    2016-05-05

    The layered MnWO{sub 4}/reduced graphene oxide (MnWO{sub 4}/RGO) was prepared through a facile one-pot low-temperature hydrothermal route without using any templates. The structure and morphology of MnWO{sub 4}/RGO nanocomposite were characterized through X-ray diffraction, Raman spectra, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption/desorption and thermo-gravimetric analysis. While its electrochemical behaviors were investigated using cyclic voltammograms, galvanostatic charge/discharge and electrochemical impedance spectroscopy. In the case of three electrode cells, MnWO{sub 4}/RGO with 7.28 wt% RGO content fulfilled a maximum specific capacitance of 288 F g{sup −1} at 5 mV s{sup −1} with the potential range from −0.35–0.55 V. While in the two electrode cell, it obtained a maximum specific capacitance of 109 F g{sup −1} at 5 mV s{sup −1} and displayed the cycle life of 14.9% capacitance decline after 6000 cycles. - Highlights: • The MnWO{sub 4}/RGO was first prepared through a facile hydrothermal route. • MnWO{sub 4}/RGO composite show much higher specific capacitances than pure MnWO{sub 4}. • The electrochemical properties of MnWO{sub 4}/RGO arise from the synergistic effect.

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

    Indian Academy of Sciences (India)

    This paper presents ethanol vapour sensing properties of WO3 thick films. In this work, the WO3 thick films were prepared by standard screen-printing method. These films were characterized by X-ray diffraction (XRD) measurements and scanning electron microscopy (SEM). The ethanol vapour sensing properties of these ...

  8. 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.

  9. 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

  10. Selective hydrothermal method to create patterned and photoelectrochemically effective Pt/WO3 Interfaces

    NARCIS (Netherlands)

    Zoontjes, M.G.C.; Huijben, Mark; Baltrusaitis, Jonas; van der Wiel, Wilfred Gerard; Mul, Guido

    2013-01-01

    A hydrothermal method based on the use of hydrogen peroxide is described to grow a homogeneous layer of tungsten oxide (WO3) on a platinum (Pt) film supported on a silicon wafer. WO3 growth is highly selective for Pt when present on silicon in a patterned arrangement, demonstrating that Pt catalyzes

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

    Indian Academy of Sciences (India)

    TECS

    Abstract. This paper presents ethanol vapour sensing properties of WO3 thick films. In this work, the WO3 thick films were prepared by standard screen-printing method. These films were characterized by X-ray diffraction (XRD) measurements and scanning electron microscopy (SEM). The ethanol vapour sensing pro-.

  12. Electrical and optical properties of ZnO–WO3 nanocomposite and its ...

    Indian Academy of Sciences (India)

    Abstract. This study reports the humidity sensing characteristics of ZnO–WO3 nanocomposite. Pellet samples of. 0–5 weight% ZnO in WO3 were sintered from 300 to 600◦C. When exposed to humidity, the resistance of the sensing samples was found to decrease with increase in relative humidity (RH). Five percent ...

  13. 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.

  14. 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.

  15. Tribological Behaviour of OA-Capped WO3 Nanoparticles as an Additive to Base Oils

    International Nuclear Information System (INIS)

    Siti Fazlili Abdullah

    2008-01-01

    Oleic acid (OA) capped wolfram (VI) oxide, WO 3 nanoparticles were chemically synthesized and characterized by means of Fourier Transform-Infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). The tribological properties of the capped WO 3 nanoparticles as an additive in base oils were investigated using a four-ball machine. Results show that OA-capped WO 3 nanoparticles are able to prevent water adsorption and capable of being dispersed stable in organic solvents which is base oils. The as-prepared capped WO 3 nanoparticles have an average size of 15 nm. In addition, OA-capped WO 3 nanoparticles as an additive in base oils perform good anti-wear (AW) and anti-friction (AF) properties owing to the formation of a boundary film. (author)

  16. 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.

  17. 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.

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

    Science.gov (United States)

    Chen, Deliang; Hou, Xianxiang; Wen, Hejing; Wang, Yu; Wang, Hailong; Li, Xinjian; Zhang, Rui; Lu, Hongxia; Xu, Hongliang; Guan, Shaokang; 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 WO3 nanoplates as active elements have been investigated in this paper. Single-crystalline WO3 nanoplates were synthesized through a topochemical approach on the basis of intercalation chemistry (Chen et al 2008 Small 4 1813). The as-obtained WO3 nanoplate pastes were coated on the surface of an Al2O3 ceramic microtube with four Pt electrodes to measure their alcohol-sensing properties. The results show that the WO3 nanoplate sensors are highly sensitive to alcohols (e.g., methanol, ethanol, isopropanol and butanol) at moderate operating temperatures (260-360 °C). For butanol, the WO3 nanoplate sensors have a sensitivity of 31 at 2 ppm and 161 at 100 ppm, operating at 300 °C. For other alcohols, WO3 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 WO3 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 WO3 nanoparticle sensors have not shown such a linear relationship. The sensitivities of the WO3 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 WO3 nanoplates, due to the advantages of the effective adsorption and rapid diffusion of the alcohol molecules.

  19. Photoactivity and stability of Ag2WO4 for organic degradation in aqueous suspensions

    International Nuclear Information System (INIS)

    Chen, Haihang; Xu, Yiming

    2014-01-01

    Graphical abstract: Both α- and β-Ag 2 WO 4 are photoactive for organic degradation in aqueous solutions, and β-Ag 2 WO 4 is more active than α-Ag 2 WO 4 under UV light, but both the catalysts are not stable against photodecomposition to form metallic silver particles. - Highlights: • Two catalysts are photoactive, but not stable for organic degradation in water under UV light. • Comparatively, β-Ag 2 WO 4 is more photoactive but less stable than α-Ag 2 WO 4 . • Metallic silver particles are formed during organic degradation under UV light. - Abstract: Silver tungstate as photocatalyst for water splitting and dye degradation has been reported, but the catalyst stability is not known. In this work, we find that both α- and β-Ag 2 WO 4 are not stable under UV light for the photocatalytic degradation of phenol and azo-dye X3B in aqueous solutions. Comparatively, β-Ag 2 WO 4 was more photoactive, but less stable than α-Ag 2 WO 4 . Solid characterization with X-ray diffraction and scanning electron microscope showed that metallic silver particles were produced with the two catalysts, consequently resulting into decrease in the activity for organic degradation. Measurement of photoluminescence revealed that β-Ag 2 WO 4 had a weaker band gap emission and higher portion of structural defects than α-Ag 2 WO 4 . A possible mechanism responsible for the observed difference in photoactivity and stability between the two tungstates is proposed

  20. The enhanced alcohol-sensing response of ultrathin WO{sub 3} nanoplates

    Energy Technology Data Exchange (ETDEWEB)

    Chen Deliang; Hou Xianxiang; Wen Hejing; Wang Yu; Wang Hailong; Zhang Rui; Lu Hongxia; Xu Hongliang; Guan Shaokang [School of Materials Science and Engineering, Zhengzhou University, 100 Science Road, Zhengzhou 450001 (China); Li Xinjian [School of Physics and Engineering, Zhengzhou University, 100 Science Road, Zhengzhou 450001 (China); Sun Jing; Gao Lian, E-mail: dlchen@zzu.edu.cn, E-mail: dlchennano@hotmail.com [The State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

    2010-01-22

    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{sub 3} nanoplates as active elements have been investigated in this paper. Single-crystalline WO{sub 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{sub 3} nanoplate pastes were coated on the surface of an Al{sub 2}O{sub 3} ceramic microtube with four Pt electrodes to measure their alcohol-sensing properties. The results show that the WO{sub 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{sub 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{sub 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{sub 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{sub 3} nanoparticle sensors have not shown such a linear relationship. The sensitivities of the WO{sub 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{sub 3} nanoplates, due to the advantages of the effective adsorption and rapid diffusion of the alcohol molecules.

  1. 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

  2. Optical spectroscopy on multiferroic MnWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Moeller, Thomas; Hemberger, Joachim; Grueninger, Markus [2. Physikalisches Institut, Universitaet zu Koeln (Germany); Pimenov, Andrei; Shuvaev, Alexey [Experimentelle Physik 4, Universitaet Wuerzburg (Germany); Becker-Bohaty, Petra; Bohaty, Ladislav [Institut fuer Kristallographie, Universitaet zu Koeln (Germany)

    2008-07-01

    MnWO{sub 4} (Huebnerite) crystallizes in a monoclinic crystal structure composed of alternating layers of Mn{sup 2+} and W{sup 6+} ions which are octahedrally coordinated by oxygen ions. The partially frustrated spin system exhibits a negative Curie-Weiss temperature T{sub CW}{approx}-75 K in the paramagnetic regime and undergoes a sequence of transitions into complex antiferromagnetic phases below T{sub N}{approx}13.5 K, including transitions from commensurate to incommensurate and collinear to non-collinear magnetic order, which are connected to the onset or decay of ferroelectric polarization. Thus MnWO{sub 4} belongs to the class of multiferroics. We present a detailed study of the phonon modes of this compound based on polarized reflectivity measurements in the FIR and MIR regime. In addition, polarized transmission measurements in the sub-mm regime below the phonon frequencies have been carried out in order to investigate the low-energy magnetoelectric excitations, so-called electro-magnons.

  3. Combustion synthesis and characterization of nanocrystalline WO3.

    Science.gov (United States)

    Morales, Walter; Cason, Michael; Aina, Olawunmi; de Tacconi, Norma R; Rajeshwar, Krishnan

    2008-05-21

    The energy payback time associated with the semiconductor active material is an important parameter in a photovoltaic solar cell device. Thus lowering the energy requirements for the semiconductor synthesis step or making it more energy-efficient is critical toward making the overall device economics more competitive relative to other nonpolluting energy options. In this communication, combustion synthesis is demonstrated to be a versatile and energy-efficient method for preparing inorganic oxide semiconductors such as tungsten trioxide (WO3) for photovoltaic or photocatalytic solar energy conversion. The energy efficiency of combustion synthesis accrues from the fact that high process temperatures are self-sustained by the exothermicity of the combustion process, and the only external thermal energy input needed is for dehydration of the fuel/oxidizer precursor mixture and bringing it to ignition. Importantly, we show that, in this approach, it is also possible to tune the optical characteristics of the oxide semiconductor (i.e., shift its response toward the visible range of the electromagnetic spectrum) in situ by doping the host semiconductor during the formative stage itself. As a bonus, the resultant material shows enhanced surface properties such as markedly improved organic dye uptake relative to benchmark samples obtained from commercial sources. Finally, this synthesis approach requires only very simple equipment, a feature that it shares with other "mild" inorganic semiconductor synthesis routes such as sol-gel chemistry, chemical bath deposition, and electrodeposition. The present study constitutes the first use of combustion synthesis for preparing WO3 powder comprising nanosized particles.

  4. 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

  5. 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.

  6. Sensing performance of palladium-functionalized WO3 nanowires by a drop-casting method

    International Nuclear Information System (INIS)

    Chávez, F.; Pérez-Sánchez, G.F.; Goiz, O.; Zaca-Morán, P.; Peña-Sierra, R.; Morales-Acevedo, A.; Felipe, C.; Soledad-Priego, M.

    2013-01-01

    In this work, we show a simple way to functionalize tungsten oxide nanowires (WO 3 -NWs) using a saturated palladium chloride (PdCl 2 ) solution deposited by a drop-casting method. WO 3 -NWs were synthesized by close-spaced chemical vapor deposition (CSVT). The morphological and structural characterizations showed that the diameters of WO 3 -NWs are in the range from 50 to 200 nm with lengths above 10 μm, and correspond to the orthorhombic phase of WO 3 , respectively. The sensor was fabricated using the WO 3 -NWs and tested with hydrogen and volatile organic compounds (VCO's). A comparative study was done on the sensing performance, before and after the Palladium functionalization of the WO 3 -NWs, considering a wide range of gas concentrations and moderate operating temperatures (100–400 °C). The results show that this simple functionalization process significantly increases the sensor sensitivity and reduces the time constants. In addition, it has been shown that at 300 °C the decorated sensor becomes more selective to hydrogen and xylene for all concentrations considered in this research. Finally, the mechanisms involved in improving the gas sensing properties of WO 3 -NWs functionalized with Palladium are discussed.

  7. 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...

  8. Structure, morphology and electrocatalytic properties of WO x thin films prepared by reactive pulsed laser deposition

    Science.gov (United States)

    Fominski, V. Y.; Grigoriev, S. N.; Romanov, R. I.; Volosova, M. A.; Fominski, D. V.; Irzhak, A. V.

    2017-12-01

    Nanostructured WO xheated substrate resulted in the formation of nanoneedles and nanosheets. Fairly good catalytic properties in hydrogen evolution reaction (HER) and in electrolytic Pt deposition were revealed for the WO x films that consisted of loosely packed ball-like nanocrystals possessing a size of ∼20 nm. The catalytic activity of the films consisted of nanoneedles and nanosheets was not good enough. Adjustable electrolytic deposition of Pt on the nanostructured WO x support film allowed to prepare effective hybrid HER catalyst containing only ∼7 μg/cm2 of Pt.

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. Visible-light-induced WO3/g-C3N4 composites with enhanced photocatalytic activity.

    Science.gov (United States)

    Huang, Liying; Xu, Hui; Li, Yeping; Li, Huaming; Cheng, Xiaonong; Xia, Jixiang; Xu, Yuanguo; Cai, Guobin

    2013-06-28

    Novel WO3/g-C3N4 composite photocatalysts were prepared by a calcination process with different mass contents of WO3. The photocatalysts were characterized by thermogravimetric analysis (TG), powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflection spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and electrochemical impedance spectroscopy (EIS). The photocatalytic activity of the photocatalysts was evaluated by degradation of methylene blue (MB) dye and 4-chlorophenol (4-CP) under visible light. The results indicated that the WO3/g-C3N4 composite photocatalysts showed higher photocatalytic activity than both the pure WO3 and pure g-C3N4. The optimum photocatalytic activity of WO3/g-C3N4 at a WO3 mass content of 9.7% under visible light irradiation was up to 4.2 times and 2.9 times as high as that of the pure WO3 and pure g-C3N4, respectively. The remarkably increased performance of WO3/g-C3N4 was mainly attributed to the synergistic effect between the interface of WO3 and g-C3N4, including enhanced optical absorption in the visible region, enlarged specific surface areas and the suitable band positions of WO3/g-C3N4 composites.

  15. 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

  16. 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

  17. Hydrothermal Fabrication of WO3 Hierarchical Architectures: Structure, Growth and Response

    Directory of Open Access Journals (Sweden)

    Chuan-Sheng Wu

    2015-07-01

    Full Text Available Recently hierarchical architectures, consisting of two-dimensional (2D nanostructures, are of great interest for potential applications in energy and environmental. Here, novel rose-like WO3 hierarchical architectures were successfully synthesized via a facile hydrothermal method. The as-prepared WO3 hierarchical architectures were in fact assembled by numerous nanosheets with an average thickness of ~30 nm. We found that the oxalic acid played a significant role in governing morphologies of WO3 during hydrothermal process. Based on comparative studies, a possible formation mechanism was also proposed in detail. Furthermore, gas-sensing measurement showed that the well-defined 3D WO3 hierarchical architectures exhibited the excellent gas sensing properties towards CO.

  18. 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.

  19. A comparative study of heterostructured CuO/CuWO4 nanowires and thin films

    Science.gov (United States)

    Polyakov, Boris; Kuzmin, Alexei; Vlassov, Sergei; Butanovs, Edgars; Zideluns, Janis; Butikova, Jelena; Kalendarev, Robert; Zubkins, Martins

    2017-12-01

    A comparative study of heterostructured CuO/CuWO4 core/shell nanowires and double-layer thin films was performed through X-ray diffraction, confocal micro-Raman spectroscopy and electron (SEM and TEM) microscopies. The heterostructures were produced using a two-step process, starting from a deposition of amorphous WO3 layer on top of CuO nanowires and thin films by reactive DC magnetron sputtering and followed by annealing at 650 °C in air. The second step induced a solid-state reaction between CuO and WO3 oxides through a thermal diffusion process, revealed by SEM-EDX analysis. Morphology evolution of core/shell nanowires and double-layer thin films upon heating was studied by electron (SEM and TEM) microscopies. A formation of CuWO4 phase was confirmed by X-ray diffraction and confocal micro-Raman spectroscopy.

  20. 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.

  1. 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.

  2. Characterization of WO3 Thin Films Grown on Silicon by HFMOD

    Directory of Open Access Journals (Sweden)

    Joel Díaz-Reyes

    2013-01-01

    modes of as-deposited WO3 and annealed at 500°C present clearly differences. WO3 band gap energy can be varied from 2.92 to 3.15 eV by annealing WO3 from 0 to 500°C as was obtained by transmittance measurements. The photoluminescence response of the as-deposited film presents three radiative transitions observed at 2.85, 2.41, and 2.04 eV that could be associated with oxygen vacancies; the first one is shifted to higher energies as the annealing temperature is increased due to the change of crystalline phase of the WO3.

  3. Structural and optical properties of WO{sub 3} films deposited by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Y.S., E-mail: yshzou75@gmail.com; Zhang, Y.C.; Lou, D.; Wang, H.P.; Gu, L.; Dong, Y.H.; Dou, K.; Song, X.F.; Zeng, H.B.

    2014-01-15

    Highlights: • Monoclinic WO{sub 3} films were prepared by pulsed laser deposition. • The WO{sub 3} films exhibited preferred (0 0 2) orientation at elevated temperature. • The structure and optical properties of WO{sub 3} films depended on substrate temperature. • The optical band gap of WO{sub 3} films decreased as substrate temperature increased. -- Abstract: Tungsten oxide (WO{sub 3}) films were prepared on Si (1 0 0) and fused silica substrates by pulsed laser deposition (PLD). The effects of substrate temperature on the morphology, microstructure and optical properties of WO{sub 3} films were investigated by scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectra and UV–visible spectrophotometer. It was found that the microstructure, morphology and optical properties strongly depend on the substrate temperature. The X-ray diffraction and Raman results indicate that the amorphous WO{sub 3} films are obtained at substrate temperatures below 200 °C whereas the films grown above 300 °C exhibit predominantly (0 0 2) plane orientation, representing the monoclinic structure. The surface roughness, film crystallinity and grain size of the films increase with increasing substrate temperature. The films prepared at substrate temperatures ranging from 300 to 600 °C exhibit high averaged transparency over 60% in the visible region. The optical band gaps of the films are found to decrease monotonically from 3.22 to 3.05 eV as the substrate temperature increases from 200 to 600 °C due to the crystallization of deposited WO{sub 3} film.

  4. Facile and controlled synthesis of aligned WO3 nanorods and nanosheets as an efficient photocatalyst material

    Science.gov (United States)

    Ahmed, Bilal; Kumar, Sumeet; Ojha, Animesh K.; Donfack, P.; Materny, A.

    2017-03-01

    In this work, we have performed a facile and controlled synthesis of WO3 nanorods and sheets in different crystal phases (triclinic, orthorhombic and monoclinic) of WO3 using the sol-gel method. The detailed structures of the synthesized materials were examined by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy measurements. The shapes and crystal phases of the WO3 nanostructures were found to be highly dependent on the calcination temperature. The variation in crystalline phases and shapes is modified the electronic structure of the samples, which causes a variation in the value of optical band gap. The value of the Raman line intensity ratio I264/I320 has been successfully used to identify the structural transition from the triclinic to the orthorhombic phase of WO3. The PL spectra of the synthesized products excited at wavelengths 380, 400, and 420 nm exhibit intense emission peaks that cover the complete visible range (blue-green-red). The emission peaks at 460 and 486 nm were caused by the near band-edge and band to band transition, respectively. The peaks in spectral range 500-600 nm might be originated from the presence of oxygen vacancies lying within the energy band gap. The synthesized WO3 nanostructures showed improved photocatalytic activity for the photodegradation of MB dye. The enhanced photocatalytic activity of WO3 nanosheets compared to WO3 nanorods for photodegradation of methylene blue (MB) dye could be due to the shape of the nanostructured WO3. The sheet type of structure provides more active surface for the interaction of dye molecules compared to the rods, which results in a more efficient degradation of the dye molecules.

  5. [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.

  6. The novel phase transition of NaBi(WO4)2 under high pressure

    International Nuclear Information System (INIS)

    Ma, Chunli; Cui, Hang; Li, Fangfei; Wang, Jingshu; Wu, Xiaoxin; Zhang, Jian; Zhou, Qiang; Liu, Jinghe; Cui, Qiliang

    2013-01-01

    The Raman and synchrotron angle-dispersive X-ray diffraction studies have been performed on NaBi(WO 4 ) 2 under high pressure up to 30.7 and 36.2 GPa, respectively, at room temperature. With pressure increases to ∼7.0 GPa, the structure of NaBi(WO 4 ) 2 begins to transform from tetragonal (I4 1 /a) into monoclinic (P2/m), and the phase transition completes around 13 GPa. With pressure higher than 29.0 GPa, the NaBi(WO 4 ) 2 turns into amorphous state. The random arrangement of Na + and Bi 3+ in short-range ordered scheelite NaBi(WO 4 ) 2 results in the tetragonal to monoclinic phase transition, which is different from that observed in AWO 4 tungstates and AMoO 4 molybdates (A=Ca, Sr, Ba, Pb, Eu, Cd). - Graphical abstract: The NaBi(WO 4 ) 2 transforms from tetragonal into monoclinic, which starts around 7 GPa and completes at about 13 GPa. With pressure higher than 29 GPa, the NaBi(WO 4 ) 2 turns into amorphous state. Highlights: ► Raman and X-ray diffraction studies performed on NaBi(WO 4 ) 2 up to 30.7 and 36.2 GPa, respectively. ► The tetragonal (I4 1 /a) into monoclinic (P2/m) phase transition is determined. ► With pressure higher than 29 GPa, the NaBi(WO 4 ) 2 ultimately turns into amorphous state. ► The ambient pressure bulk modulus and volume of tetragonal and monoclinic phases are obtained

  7. UV-VUV synchrotron radiation spectroscopy of NiWO4

    Science.gov (United States)

    Kuzmin, A.; Pankratov, V.; Kalinko, A.; Kotlov, A.; Shirmane, L.; Popov, A. I.

    2016-07-01

    Photoluminescence and excitation spectra of microcrystalline and nanocrystalline nickel tungstate (NiWO4) were measured using UV-VUV synchrotron radiation source. The origin of the bands is interpreted using comparative analysis with isostructural ZnWO4 tungstate and based on the results of recent first-principles band structure calculations. The influence of the local atomic structure relaxation and of Ni2+ intra-ion d-d transitions on the photoluminescence band intensity are discussed.

  8. 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)

  9. 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.

  10. 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.

  11. 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.

  12. Epitaxial NiWO4 films on Ni(110): Experimental and theoretical study of surface stability

    Science.gov (United States)

    Doudin, N.; Pomp, S.; Blatnik, M.; Resel, R.; Vorokhta, M.; Goniakowski, J.; Noguera, C.; Netzer, F. P.; Surnev, S.

    2017-05-01

    Despite the application potential of nickel tungstate (NiWO4) in heterogeneous catalysis, humidity and gas sensing, etc, its surfaces have essentially remained unexplored. In this work, NiWO4 nanoparticles and films with the wolframite structure have been grown via a solid-state reaction of (WO3)3 clusters and a NiO(100) film on a Ni(110) crystal surface and characterized by a variety of experimental techniques, including x-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM) and x-ray diffraction (XRD), combined with ab-initio density functional theory (DFT) calculations. NiWO4 grows initially as three-dimensional (3D) crystalline nanoparticles displaying mainly two crystalline facets vicinal to the (100) surface, which merge with increasing the (WO3)3 coverage into a quasi-continuous epitaxial film. The DFT results provide an account of the energetics of NiWO4 low index surfaces and highlight the role of faceting in the stabilization of extended polar (100) terraces. These combined experimental and theoretical results show that interaction with a metal substrate and vertical confinement may stabilize oxide nano-objects with high energy facets, able to enhance their reactivity.

  13. 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

  14. Thermal effects associated with the Raman spectroscopy of WO3 gas-sensor materials.

    Science.gov (United States)

    Garcia-Sanchez, Raul F; Ahmido, Tariq; Casimir, Daniel; Baliga, Shankar; Misra, Prabhakar

    2013-12-19

    Metal oxides are suitable for detecting, through conductive measurements, a variety of reducing and oxidizing gases in environmental and sensing applications. Metal-oxide gas sensors can be developed with the goal of sensing gases under specific conditions and, as a whole, are heavily dependent on the manufacturing process. Tungsten oxide (WO3) is a promising metal-oxide material for gas-sensing applications. The purpose of this paper is to determine the existence of a correlation between thermal effects and the changes in the Raman spectra for multiple WO3 structures. We have obtained results utilizing Raman spectroscopy for three different structures of WO3 (monoclinic WO3 on Si substrate, nanopowder, and nanowires) that have been subjected to temperatures in the range of 30-160 °C. The major vibrational modes of the WO3:Si and the nanopowder samples, located at ~807, ~716, and ~271 cm(-1), correspond to the stretching of O-W-O bonds, the stretching of W-O, and the bending of O-W-O, respectively; these are consistent with a monoclinic WO3 structure. However in the nanowires sample only asymmetric stretching of the W-O bonds occurs, resulting in a 750 cm(-1) band, and the bending of the O-W-O mode (271 cm(-1)) is a stretching mode (239 cm(-1)) instead, suggesting the nanowires are not strictly monoclinic. The most notable effect of increasing the temperature of the samples is the appearance of the bending mode of W-OH bonds in the approximate range of 1550-1150 cm(-1), which is related to O-H bonding caused by humidity effects. In addition, features such as those at 750 cm(-1) for nanowires and at 492 and 670 cm(-1) for WO3:Si disappear as the temperature increases. A deeper understanding of the effect that temperature has on the Raman spectral characteristics of a metal oxide such as WO3 has helped to extend our knowledge regarding the behavior of metal oxide-gas interactions for sensing applications. This, in turn, will help to develop theoretical models for

  15. 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.

  16. Synthesis and photoluminescence of Tb3+ Activated NaY(WO4)2 phosphors

    International Nuclear Information System (INIS)

    Liu, Xiaohua; Xiang, Wendou; Chen, Fengming; Zhang, Wei; Hu, Zhengfa

    2012-01-01

    Graphical abstract: The phosphor powders of NaY(WO 4 ) 2 :Tb 3+ were prepared by solid state reaction. The dependence of luminescence intensity on the Tb 3+ concentration was investigated. Highlights: ► We synthesize NaY(WO 4 ) 2 :Tb 3+ phosphors by the solid-state reaction technique. ► We observe and explain the blue shifting of excitation peak positions of CTBs. ► The PL from 5 D 3 level become less probable with increasing the Tb 3+ content. ► The PL intensity increases with Tb 3+ content without concentration quenching. ► NaY(WO 4 ) 2 :Tb 3+ has potential application as a green emitting phosphor in lamps. -- Abstract: The novel yellowish green phosphor powders of NaY(WO 4 ) 2 doped with Tb 3+ were prepared by solid-state reaction. The powder samples were characterized by X-ray diffraction and photoluminescence. X-ray diffraction analysis showed that the phosphors sintered at 900 °C for 6 h were a pure NaY(WO 4 ) 2 phase for all the Tb 3+ doping concentrations. The room temperature excitation spectra vary with the Tb 3+ concentration and consist of an intense charge transfer band of WO 4 2− group and weak intra-4f 8 transition absorption peaks of Tb 3+ ions. The photoluminescence spectra, excited at the peak wavelengths of charge transfer bands, consist of the characteristic Tb 3+ emission transitions from 5 D 3 and 5 D 4 excited levels to 7 F J (J = 3–6) levels. The dependence of luminescence intensity on the Tb 3+ concentration in NaY(WO 4 ) 2 :Tb phosphors was investigated.

  17. 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

  18. 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)

  19. Structural evolution, growth mechanism and photoluminescence properties of CuWO4nanocrystals.

    Science.gov (United States)

    Souza, E L S; Sczancoski, J C; Nogueira, I C; Almeida, M A P; Orlandi, M O; Li, M S; Luz, R A S; Filho, M G R; Longo, E; Cavalcante, L S

    2017-09-01

    Copper tungstate (CuWO 4 ) crystals were synthesized by the sonochemistry (SC) method, and then, heat treated in a conventional furnace at different temperatures for 1h. The structural evolution, growth mechanism and photoluminescence (PL) properties of these crystals were thoroughly investigated. X-ray diffraction patterns, micro-Raman spectra and Fourier transformed infrared spectra indicated that crystals heat treated and 100°C and 200°C have water molecules in their lattice (copper tungstate dihydrate (CuWO 4 ·2H 2 O) with monoclinic structure), when the crystals are calcinated at 300°C have the presence of two phase (CuWO 4 ·2H 2 O and CuWO 4 ), while the others heat treated at 400°C and 500°C have a single CuWO 4 triclinic structure. Field emission scanning electron microscopy revealed a change in the morphological features of these crystals with the increase of the heat treatment temperature. Transmission electron microscopy (TEM), high resolution-TEM images and selected area electron diffraction were employed to examine the shape, size and structure of these crystals. Ultraviolet-Visible spectra evidenced a decrease of band gap values with the increase of the temperature, which were correlated with the reduction of intermediary energy levels within the band gap. The intense photoluminescence (PL) emission was detected for the sample heat treat at 300°C for 1h, which have a mixture of CuWO 4 ·2H 2 O and CuWO 4 phases. Therefore, there is a synergic effect between the intermediary energy levels arising from these two phases during the electronic transitions responsible for PL emissions. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. 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%

  1. 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.

  2. Multiferroic hysteresis in MnWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Finger, Thomas; Komarek, Alexander; Senff, Daniel; Braden, Markus [II. Physikalisches Institut, Universitaet zu Koeln (Germany); Becker-Bohaty, Petra; Bohaty, Ladislav [Institut fuer Kristallographie, Universitaet zu Koeln (Germany); Regnault, Louis-Pierre [CNG-Grenoble / ILL, Grenoble (France); Schmalzl, Karin; Schmidt, Wolfgang [JCNS / ILL, Grenoble (France)

    2009-07-01

    Multiferroic materials or compounds with a strong magnetoelectric effect posses a large application potential in data storage techniques: one would like to replace the common magnetic writing by an electric process, as the generation of the magnetic fields is energy expensive. Quite recently, systems with a peculiar spiral magnetic order were shown to directly induce a spontaneous electric polarization and to exhibit giant magnetoelectric and magnetocapacitance effects, among them MnWO{sub 4}, which crystallizes in a monoclinic structure and undergoes several magnetic phase transitions as a function of temperature. From these phases only the incommensurate non-collinear ordering in the AF2-phase induces an electric polarization and large magnetoelectric effects, fully consistent with recent theories. We have succeeded for the first time to observe a chirality hysteresis curve driven by the electric field. These data can give important information about the pinning of the multiferroic order, which is relevant in view of future applications. We present our temperature dependent studies on the multiferroic hysteresis as well as a characterization of the second harmonics of the spiral.

  3. 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.

  4. 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.

  5. Direct solar water splitting cell using water, WO3, Pt, and polymer electrolyte membrane

    International Nuclear Information System (INIS)

    He Xiaoming; Boehm, Robert F.

    2009-01-01

    A solar water splitting cell composed of WO 3 , Polymer Electrolyte Membrane (PEM) and Pt was constructed for producing hydrogen from deionized water in sunlight. Spectral responsivity measurements under various temperatures and bias voltages were conducted for the cell using the Incident Photon to Current Efficiency (IPCE) method. For comparison, a known WO 3 Photo Electro Chemical (PEC) cell containing H 3 PO 4 electrolyte, WO 3 /H 3 PO 4 /Pt, was tested using the same test method. The WO 3 /PEM-H 2 O/Pt cell showed better Quantum Efficiency (QE) performance compared to that obtained from the cell with the chemical electrolyte. For the first time, spectral responsivity of photo water splitting process without bias power was unveiled in the new WO 3 cell, demonstrating the self-sustained photo electrolysis capability. Bias voltage effect on Solar to Hydrogen (STH) conversion efficiency was dramatic in the range from 0.2 V to 1.2 V and suppressions of STH were observed when high bias voltages were applied. In addition, a strong temperature effect on the energy conversion efficiency at high bias voltage was observed in the cell containing PEM-H 2 O, revealing that the STH at 54 °C is nearly five times that at 14 °C.

  6. 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...

  7. 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....

  8. Cycloidal magnetism driven ferroelectricity in double tungstate LiFe (WO4)2

    Science.gov (United States)

    Liu, Meifeng; Lin, Lingfang; Zhang, Yang; Li, Shaozhen; Huang, Qingzhen; Garlea, V. Ovidiu; Zou, Tao; Xie, Yunlong; Wang, Yu; Lu, Chengliang; Yang, Lin; Yan, Zhibo; Wang, Xiuzhang; Dong, Shuai; Liu, Jun-Ming

    2017-05-01

    Tungstates A WO4 with the wolframite structure characterized by the A O6 octahedral zigzag chains along the c axis can be magnetic if A =Mn , Fe, Co, Cu, Ni. Among them, MnWO4 is a unique member with a cycloid Mn2 + spin order developed at low temperature, leading to an interesting type-II multiferroic behavior. However, so far no other multiferroic material in the tungstate family has been found. In this work, we present the synthesis and the systematic study of the double tungstate LiFe (WO4)2 . Experimental characterizations including structural, thermodynamic, magnetic, neutron powder diffraction, and pyroelectric measurements unambiguously confirm that LiFe (WO4)2 is the secondly found multiferroic system in the tungstate family. The cycloidal magnetism driven ferroelectricity is also verified by density functional theory calculations. Although here the magnetic couplings between Fe ions are indirect, namely via the so-called super-super-exchanges, the temperatures of magnetic and ferroelectric transitions are surprisingly much higher than those of MnWO4.

  9. Photocatalytic decomposition of N2O over g-C3N4/WO3photocatalysts.

    Science.gov (United States)

    Reli, Martin; Svoboda, Ladislav; Šihor, Marcel; Troppová, Ivana; Pavlovský, Jiří; Praus, Petr; Kočí, Kamila

    2017-11-24

    Although the nitrous oxide belongs among three of the most contributing greenhouse gases to global warming, it is quite neglected by photocatalytic society. The g-C 3 N 4 and WO 3 composites were therefore tested for the photocatalytic decomposition of N 2 O for the first time. The pure photocatalysts were prepared by simple calcination of precursors, and the composites were prepared by mixing of suspension of pure components in water followed by calcination. The structural (X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy), textural (N 2 physisorption), and optical properties (diffuse reflectance spectroscopy, photoluminescence spectroscopy, photoelectrochemical measurements) of all composites were correlated with photocatalytic activity. The experimental results and results from characterization techniques confirmed creation of Z-scheme in the WO 3 /g-C 3 N 4 composites, which was confirmed by hydroxyl radicals' trapping measurements. The photocatalytic decomposition of N 2 O was carried out in the presence of UVA light (peak intensity at 365 nm) and the 1:2 WO 3 /g-C 3 N 4 composite was the most active one, but the photocatalytic activity was just negligibly higher than that of pure WO 3 . This is caused by relatively weak interaction between WO 3 and g-C 3 N 4 which was revealed from XPS.

  10. 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.

  11. Characterization of PLD grown WO3 thin films for gas sensing

    Science.gov (United States)

    Boyadjiev, Stefan I.; Georgieva, Velichka; Stefan, Nicolaie; Stan, George E.; Mihailescu, Natalia; Visan, Anita; Mihailescu, Ion N.; Besleaga, Cristina; Szilágyi, Imre M.

    2017-09-01

    Tungsten trioxide (WO3) thin films were grown by pulsed laser deposition (PLD) with the aim to be applied in gas sensors. The films were studied by atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and profilometry. To study the gas sensing behavior of these WO3 films, they were deposited on quartz resonators and the quartz crystal microbalance (QCM) method was applied to analyze their gas sensitivity. Synthesis of tetragonal-WO3 films starting from a target with predominantly monoclinic WO3 phase was observed. The films deposited at 300 °C presented a surface topology favorable for the sorption properties, consisting of a film matrix with protruding craters/cavities. QCM prototype sensors with such films were tested for NO2 sensing. The PLD grown WO3 thin films show good sensitivity and fast reaction at room temperature, even in as-deposited state. With the presented technology, the manufacturing of QCM gas sensors is simple, fast and cost-effective, and it is also suitable for energy-effective portable equipment for on-line monitoring of environmental changes.

  12. Synthesis of ZnWO4 Electrode with tailored facets: Deactivating the Microorganisms through Photoelectrocatalytic methods

    Science.gov (United States)

    Zhan, Su; Zhou, Feng; Huang, Naibao; Liu, Yujun; He, Qiuchen; Tian, Yu; Yang, Yifan; Ye, Fei

    2017-01-01

    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, ZnWO4 with different exposed facets was synthesized by hydrothermal method, and ZnWO4 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). ZnWO4 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 ZnWO4 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 ZnWO4.

  13. 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.

  14. 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 An efficient room temperature catalyzed oxidation of cyclohexane to cyclohexanone (K) and cyclohexanol (A) was achieved over hetero-mixed tungsten–vanadia (WO(sub3)/V(sub2)O(sub5)) using H(sub2)O(sub2) oxidant. WO(sub3)/V(sub2)O(sub5) exhibited high...

  15. 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)

  16. 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 nanorod. The prepared Au loaded MnWO4 nanorod demonstrated greatly enhanced photocatalytic activity in decomposing 2-propanol and evolving CO2 in gas phase and phenol in aqueous phase compared to bare MnWO4 and commercial TiO2 nanoparticles (Degussa P25...

  17. 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

  18. Light-induced spatial separation of charges toward different crystal facets of square-like WO3.

    Science.gov (United States)

    Gong, Huihua; Ma, Ruirui; Mao, Fang; Liu, Kewei; Cao, Hongmei; Yan, Hongjian

    2016-09-29

    Light-induced preferential migration of electrons and holes to the minor (200) and (020) facets and the dominant (002) facets of square-like WO 3 , respectively, resulted in the square-like WO 3 nanoplates with Pt loaded mainly on dominant (002) facets shows higher photocatalytic activity than that Pt loaded on the minor facets.

  19. Optical characterization of the coloration process in electrochromic amorphous and crystalline WO3 films by spectroscopic ellipsometry

    Science.gov (United States)

    Yuan, Guangzhong; Hua, Chenzheng; Huang, Li; Defranoux, Christophe; Basa, Peter; Liu, Yong; Song, Chenlu; Han, Gaorong

    2017-11-01

    Amorphous and crystalline electrochromic WO3 films exhibit quite different optical properties during coloration process. In the present work, amorphous and crystalline electrochromic WO3 films prepared by a solution method were characterized using X-ray diffraction, scanning electron microscope, and transmission electron microscope techniques. A double-layer model with sharp interfaces was established for the fitting of the ellipsometry parameters. The results show that the proton favors amorphous films more than crystalline WO3 films. The refractive indices of both amorphous and polycrystalline WO3 films decrease while extinction coefficients increase with the inserting of H+ during the coloration process. But the optical parameters of the latter are much more sensitive to the H+ ions injected compared to the amorphous WO3 during the coloration process. That is the refractive index modulation of the crystalline WO3 films is about 53% at 633 nm while that of the amorphous films about 15% at the same wavelength. The Drude-like free electron model for crystalline WO3 and hopping mechanism of small polaron for amorphous WO3 are used to explain the difference in detail. These results are very helpful for the better understanding of the coloration process and for the design of electrochromic devices.

  20. 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

  1. 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.

  2. 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)

  3. 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.

  4. Preparation and magnetic properties of CoWO{sub 4} nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Jiwei; Zhang, Endi; Ma, Jianmin; Wang, Taihong [Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education, State Key Laboratory for Chemo/Biosensing and Chemometrics, Hunan University, Changsha (China); Chang, Liao [National Oceanography Centre, University of Southampton, European Way, Southampton (United Kingdom); Wang, Ping [Department of Biology and Chemistry, City University of Hong Kong, Hong Kong (China)

    2012-09-15

    Cobalt tungstate (CoWO{sub 4}) nanocrystals with an average size of 20-50 nm were synthesized via a template- or surfactant-free hydrothermal route. The crystal structure and morphology of the as-synthesized CoWO{sub 4} sample were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Magnetic measurements on the as-synthesized CoWO{sub 4} nanocrystals indicate a Neel temperature (T{sub N}) of {proportional_to}40 K. This lower T{sub N} may be a result of the nanostructured particles that reduce the exchange coupling. The new synthetic route presented in this paper has potential applications to fabricate other metal tungstates (MWO{sub 4}) materials. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. High-pressure Raman study and lattice dynamical calculations for SrWO4

    International Nuclear Information System (INIS)

    Christofilos, D; Papagelis, K; Ves, S; Kourouklis, G A; Raptis, C

    2002-01-01

    A high-pressure Raman study of SrWO 4 reveals a pressure induced phase transition starting at 11.5 GPa. Several Raman lines exhibit a nonlinear behaviour in the pressure range of 11.5-15 GPa, which can be attributed to either stabilization of the high-pressure phase or an intermediate phase. Using a theoretical lattice dynamical calculation, based on an empirical potential model, we have obtained the Raman active mode eigenvectors giving us an insight into the phase transition mechanism. The lowest-frequency mode exhibits a negative pressure slope in the scheelite phase and involves a motion of the WO 4 tetrahedron as a whole according to the theoretical results. The experimental evidence suggests that the structure of the high-pressure phase is closely related to the scheelite structure, being formed by closely lying distorted WO 4 tetrahedra rather than involving an octahedrally coordinated W ion

  6. 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.

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

    Directory of Open Access Journals (Sweden)

    Anna Staerz

    2016-10-01

    Full Text Available 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.

  8. 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.

  9. Ag induced modifications on WO3 films studied by AFM, Raman and x-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Bittencourt, C; Llobet, E; Ivanov, P; Vilanova, X; Correig, X; Silva, M A P; Nunes, L A O; Pireaux, J J

    2004-01-01

    In this paper, the morphology, vibrational spectra and electronic properties of WO 3 films loaded with different levels of Ag, prepared by screen printing onto Si substrates and annealed in air at 600 deg. C were investigated. AFM micrography showed that the films are grain-like, and the grain size increases with an increase in the Ag loading level. Raman spectroscopy results showed the formation of a AgWO 3 bronze structure that results in a more stable film. X-ray photoelectron spectroscopy results showed that the Ag concentration is 1.8 times higher than the nominal concentration indicating that Ag diffuses to the WO 3 grain surface. No strong electronic interaction between the Ag clusters and the WO 3 grains was found. Sensors fabricated with the WO 3 : Ag films exhibited a significant increase in their sensitivity and selectivity towards NO 2 detection

  10. Humidity sensing properties of WO{sub 3} thick film resistor prepared by screen printing technique

    Energy Technology Data Exchange (ETDEWEB)

    Garde, Arun S, E-mail: arungarde@yahoo.co.in

    2014-12-25

    Highlights: • Polycrystalline WO{sub 3} Thick films are fabricated by screen printing technique. • Monoclinic phases were the majority in formation of films. • The peak at 1643 cm{sup −1} shows stretching vibrations attributed to W-OH of adsorbed H{sub 2}O. • Absorption peaks in the range 879–650 cm{sup −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{sub 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{sup −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{sup −1} are attributed to the stretching W-O-W bonds (i.e. ν [W-O{sub inter}-W]). The peak located at 983 cm{sup −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{sub 3} thick films were exposed to a wide humidity range of 20–100%. An increasing firing temperature of WO{sub 3} film increases with the sensitivity. The parameters such as sensitivity and hysteresis of the WO{sub 3} film sensors have been evaluated.

  11. 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.

  12. 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

  13. An ab initio study of WO sub 3 under pressure up to 30 GPa

    CERN Document Server

    Pagnier, T

    2003-01-01

    High-pressure polymorphs of WO sub 3 have been studied with a first-principles pseudopotential method. The medium-range (0.01-20 GPa) and high-range (20-30 GPa) polymorphs have been characterized and are compared with recent experimental results. The main new feature is the appearance of a sevenfold coordinated tungsten in the high-pressure polymorph. The subtle phase transitions that were induced from Raman spectra evolutions have not been confirmed. However, changes in the W-O distances and O-W-O and W-O-W angles may explain the changes in Raman spectra.

  14. Cellulose-Based WO3 Nanocomposites Prepared by a Sol–Gel Method at Low Temperature

    Science.gov (United States)

    Zhang, Bin; Liu, Rongzhan; Pan, Ying; Wang, Quanquan; Liu, Baojiang

    2018-01-01

    A facile method was developed to prepare cellulose-based WO3 nanocomposites. The preparation was carried out by a sol-gel method by involving treatment of tungsten hexachloride and tri-block nonionic polymer at the temperature as low as 100 °C. The morphology, surface chemical composition, functional groups, and crystal phase of the as- prepared cellulose-based WO3 nanocomposites were investigated by scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and X-ray powder diffraction, respectively.

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

    OpenAIRE

    Chen, Chien Chon

    2013-01-01

    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 col...

  16. NaBi(WO4)2 - new scintillation monocrystals for electromagnetic calorimeters

    International Nuclear Information System (INIS)

    Baryshevskij, V.G.; Zadneprovskij, B.A.; Korzhik, M.V.

    1992-01-01

    Selection of materials for complete absorption electromagnetic calorimeters is one of the most actual problems related to the development and constuction of colliders. It is established that NaBi(WO 4 ) 2 crystals are promising in terms of their application in electromagnetic calorimeters and can successfully replace lead glass. NaBi(WO 4 ) 2 crystals, 20x20x110(11X 0 ) mm, were tested at the Serpukhov accelerator when recording 26 GeV electrons. Energy resolution was 1.4 %

  17. Improvement of radiopurity level of enriched {sup 116}CdWO{sub 4} and ZnWO{sub 4} crystal scintillators by recrystallization

    Energy Technology Data Exchange (ETDEWEB)

    Barabash, A.S. [National Research Centre “Kurchatov Institute”, Institute of Theoretical and Experimental Physics, 117218 Moscow (Russian Federation); Belli, P. [INFN, sezione di Roma “Tor Vergata”, I-00133 Rome (Italy); Bernabei, R., E-mail: rita.bernabei@roma2.infn.it [INFN, sezione di Roma “Tor Vergata”, I-00133 Rome (Italy); Dipartimento di Fisica, Università di Roma “Tor Vergata”, I-00133 Rome (Italy); Borovlev, Yu.A. [Nikolaev Institute of Inorganic Chemistry, 630090 Novosibirsk (Russian Federation); Cappella, F.; Caracciolo, V.; Cerulli, R. [INFN, Laboratori Nazionali del Gran Sasso, I-67100 Assergi (AQ) (Italy); Danevich, F.A. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); Incicchitti, A. [INFN, sezione di Roma, I-00185 Rome (Italy); Dipartimento di Fisica, Università di Roma “La Sapienza”, I-00185 Rome (Italy); Kobychev, V.V. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); Konovalov, S.I. [National Research Centre “Kurchatov Institute”, Institute of Theoretical and Experimental Physics, 117218 Moscow (Russian Federation); Laubenstein, M. [INFN, Laboratori Nazionali del Gran Sasso, I-67100 Assergi (AQ) (Italy); Mokina, V.M. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); INFN, sezione di Roma, I-00185 Rome (Italy); Polischuk, O.G. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); Safonova, O.E. [V.S. Sobolev Institute of Geology and Mineralogy of the Siberian Branch of the RAS, 630090 Novosibirsk (Russian Federation); Shlegel, V.N. [Nikolaev Institute of Inorganic Chemistry, 630090 Novosibirsk (Russian Federation); and others

    2016-10-11

    As low as possible radioactive contamination of a detector plays a crucial role to improve sensitivity of a double beta decay experiment. The radioactive contamination of a sample of {sup 116}CdWO{sub 4} crystal scintillator by thorium was reduced by a factor ≈10, down to the level 0.01 mBq/kg ({sup 228}Th), by exploiting the recrystallization procedure. The total alpha activity of uranium and thorium daughters was reduced by a factor ≈3, down to 1.6 mBq/kg. No change in the specific activity (the total α activity and {sup 228}Th) was observed in a sample of ZnWO{sub 4} crystal produced by recrystallization after removing ≈0.4 mm surface layer of the crystal.

  18. Osmotic-induced phase inversion of multiple W/O/W into a W/O emulsion: rheological study of an inverted W/O emulsion

    International Nuclear Information System (INIS)

    Fredro-Kumbaradzi, Emilija; Simov, Angel; Popovska-Pavlovska, Frederika

    1995-01-01

    Osmotic induced phase inversion of a W/O/W emulsion due to the presence of NaCl in the internal aqueous phase is discussed in this paper. Visco metric measurements of the obtained W/O emulsion were also carried out in order to determine its rheological properties as well as its stability during storage. Pseudo plastic flow and negative thixotropy behavior were observed under different shearing conditions. Negative thixotropy behavior, which is most likely a result of emulsion dispersion status changes, increased with increased program time, holding time at the maximum shear rate, and max. shear rate, but decreased with repeated time of shear. Changes in the flow curves under different shear conditions were not very significant. Also, no significant changes in the rheological behavior were noticed during four weeks storage of the inverted emulsion samples at room temperature. Thus, the inverted emulsion of a W/O type is a relatively stable system. (Author)

  19. 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.

  20. Sensing performance of palladium-functionalized WO{sub 3} nanowires by a drop-casting method

    Energy Technology Data Exchange (ETDEWEB)

    Chávez, F., E-mail: f_perez_s@hotmail.com [Department of Physical-Chemical Materials, ICUAP-BUAP, 72000, Puebla (Mexico); Pérez-Sánchez, G.F. [Department of Physical-Chemical Materials, ICUAP-BUAP, 72000, Puebla (Mexico); Goiz, O. [Department of Electrical Engineering, CINVESTAV-IPN, 07360, México, D.F (Mexico); Zaca-Morán, P. [Department of Physical-Chemical Materials, ICUAP-BUAP, 72000, Puebla (Mexico); Peña-Sierra, R.; Morales-Acevedo, A. [Department of Electrical Engineering, CINVESTAV-IPN, 07360, México, D.F (Mexico); Felipe, C. [Department of Biosciences and Engineering, CIIEMAD-IPN, 07340, México, D.F (Mexico); Soledad-Priego, M. [Faculty of Electronics Sciences, FCE, 72000, Puebla (Mexico)

    2013-06-15

    In this work, we show a simple way to functionalize tungsten oxide nanowires (WO{sub 3}-NWs) using a saturated palladium chloride (PdCl{sub 2}) solution deposited by a drop-casting method. WO{sub 3}-NWs were synthesized by close-spaced chemical vapor deposition (CSVT). The morphological and structural characterizations showed that the diameters of WO{sub 3}-NWs are in the range from 50 to 200 nm with lengths above 10 μm, and correspond to the orthorhombic phase of WO{sub 3}, respectively. The sensor was fabricated using the WO{sub 3}-NWs and tested with hydrogen and volatile organic compounds (VCO's). A comparative study was done on the sensing performance, before and after the Palladium functionalization of the WO{sub 3}-NWs, considering a wide range of gas concentrations and moderate operating temperatures (100–400 °C). The results show that this simple functionalization process significantly increases the sensor sensitivity and reduces the time constants. In addition, it has been shown that at 300 °C the decorated sensor becomes more selective to hydrogen and xylene for all concentrations considered in this research. Finally, the mechanisms involved in improving the gas sensing properties of WO{sub 3}-NWs functionalized with Palladium are discussed.

  1. Microwave selective heating for size effect of water droplet in W/O emulsion with sorbitan fatty acid monostearate surfactant

    International Nuclear Information System (INIS)

    Sumi, Takuya; Horikoshi, Satoshi

    2015-01-01

    A stable water/oil (W/O) emulsion was prepared by adjustment with sorbitan fatty acid monoester surfactants. The prepared W/O emulsion was stable for 60 min in the atmosphere; however, the formation of non-uniform water droplets in the height of the emulsion in the quartz tube reactor were observed by the backscattering measurements with an infrared laser at 850 nm. The increase of temperature under microwave irradiation was influenced sensitively by the position of those water droplets. Those results were caused from the size and concentration of water droplets in the W/O emulsion. On the other hand, selective heating of the water droplets caused heating of the entire W/O emulsion, although the temperature difference between the water droplets and the oil phase was 20 °C. - Graphical abstract: The feature of a selective heating phenomenon in a W/O emulsion under microwave irradiation was investigated both practically and theoretically. Temperature profiles of emulsions stabilized with different sorbitan fatty acid monoester surfactants indicated that a smaller size distribution of water droplets leads to a higher heating rate. Moreover, computational studies suggested that water droplets in oil are 20 °C higher than the organic phase. - Highlights: • The microscopic heating features of microwaves in a W/O emulsion were examined. • The microwave heating behaviors reflected the properties of water droplets. • The heat convection process in a W/O emulsion was studied by a theoretical approach

  2. Hierarchical Bi2WO6 architectures decorated with Pd nanoparticles for enhanced visible-light-driven photocatalytic activities

    Science.gov (United States)

    Zhang, Jinniu; Chen, Tianhua; Lu, Hongbing; Yang, Zhibo; Yin, Feng; Gao, Jianzhi; Liu, Qianru; Tu, Yafang

    2017-05-01

    A new kind of hierarchical Pd-Bi2WO6 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 Bi2WO6 and Pd-Bi2WO6 nanocatalyst were examined in the degradation of Rhodamine B (RhB) dyes and phenol under visible light. The photocatalytic results showed that the Pd-Bi2WO6 nanocomposites possessed observably enhanced photocatalytic activities. Particularly, the 2.0% Pd loaded Bi2WO6 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+) and rad O2- played a crucial role in the degradation of RhB. According to the experimental results, the photocatalytic degradation mechanism of Pd-Bi2WO6 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-Bi2WO6 nanocomposites.

  3. 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.

  4. WO3/Conducting Polymer Heterojunction Photoanodes for Efficient and Stable Photoelectrochemical Water Splitting.

    Science.gov (United States)

    Jeon, Dasom; Kim, Nayeong; Bae, Sanghyun; Han, Yujin; Ryu, Jungki

    2018-02-26

    An efficient and stable heterojunction photoanode for solar water oxidation was fabricated by hybridization of WO 3 and conducting polymers (CPs). Organic/inorganic hybrid photoanodes were readily prepared by the electropolymerization of various CPs and the codeposition of tetraruthenium polyoxometalate (Ru 4 POM) water-oxidation catalysts (WOCs) on the surface of WO 3 . The deposition of CPs, especially polypyrrole (PPy) doped with Ru 4 POM (PPy:Ru 4 POM), resulted in a remarkably improved photoelectrochemical performance by the formation of a WO 3 /PPy p-n heterojunction and the incorporation of efficient Ru 4 POM WOCs. In addition, there was also a significant improvement in the photostability of the WO 3 -based photoanode after the deposition of the PPy:Ru 4 POM layer due to the suppression of the formation of hydrogen peroxide, which was responsible for corrosion. This study provides insight into the design and fabrication of novel photosynthetic and photocatalytic systems with excellent performance and stability through the hybridization of organic and inorganic materials.

  5. 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.

  6. Synthesis of wo3 nanogranular thin films by hot-wire CVD

    NARCIS (Netherlands)

    Houweling, Z.S.; Geus, J.W.; Schropp, R.E.I.

    2010-01-01

    By resistively heating tungsten filaments in a constant air flow under a reduced pressure, nanogranular amorphous WO3 thin films are deposited on glassy carbon substrates. The substrate surface temperature is monitored by a thermocouple. For deposition times of 15 min and longer, the films show

  7. Structural and functional properties of nanocomposite Au–WO3 coatings

    NARCIS (Netherlands)

    Figueiredo, N.M.; Pei, Yutao T.; De Hosson, J.T.M.; Cavaleiro, A.

    2015-01-01

    In this study several Au–WO3 nanocomposite coatings were deposited by reactive magnetron co-sputtering and characterized with respect to their chemical composition, structure, microstructure and mechanical and optical properties. The nanocomposites consist of a dual phase system of Au nanoparticles

  8. Fabrication and capacitive characteristics of conjugated polymer composite p-polyaniline/n-WO{sub 3} heterojunction

    Energy Technology Data Exchange (ETDEWEB)

    Amaechi, C.I.; Asogwa, P.U.; Ekwealor, A.B.C. [University of Nigeria, Department of Physics and Astronomy, Nsukka, Enugu State (Nigeria); Osuji, R.U.; Ezema, F.I. [University of Nigeria, Department of Physics and Astronomy, Nsukka, Enugu State (Nigeria); iThemba LABS-National Research Foundation, Nanosciences African Network (NANOAFNET), Somerset West, Western Cape Province (South Africa); University of South Africa (UNISA), UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, Pretoria (South Africa); Maaza, M. [iThemba LABS-National Research Foundation, Nanosciences African Network (NANOAFNET), Somerset West, Western Cape Province (South Africa); University of South Africa (UNISA), UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, Pretoria (South Africa)

    2014-11-15

    A nanocrystalline and porous p-polyaniline/n-WO{sub 3} dissimilar heterojunction at ambient temperature is reported. The high-quality and well-reproducible conjugated polymer composite films have been fabricated by oxidative polymerization of anilinium ion on predeposited WO{sub 3} thin film by chemical bath deposition followed by thermal annealing at 573 K for 1 h. Atomic force microscopy (AFM) analyses reveal a homogenous but irregular cluster of faceted spherically shaped grains with pores. The scanning electron microscopy confirms the porous network of grains, which is in good agreement with the AFM result. The optical absorption analysis of polyaniline/WO{sub 3} hybrid films showed that direct optical transition exist in the photon energy range 3.50-4.00 eV with bandgap of 3.70 eV. The refractive index developed peak at 445 nm in the dispersion region while the high-frequency dielectric constant, ε {sub ∞}, and the carrier concentration to effective mass ratio, N/m{sup *}, was found to be 1.58 and 1.10 x 10{sup 39} cm{sup -3}, respectively. The temperature dependence of electrical resistivity of the deposited films follows the semiconductor behavior while the C-V characteristics (Mott-Schottky plots) show that the flat band potential was -791 and 830 meV/SCE for WO{sub 3} and polyaniline. (orig.)

  9. Luminescent properties of red-light-emitting phosphors CaWO4: Eu ...

    Indian Academy of Sciences (India)

    The crystal structures of these phosphors were characterized by powder X-ray diffraction, and the luminescent properties of Eu3+-, Li+-codoped CaWO4 were investigated by diffuse reflectance spectra, photoluminescence emission spectra, photoluminescence excitation spectra, and the Commission International de L' ...

  10. Luminescent properties of red-light-emitting phosphors CaWO 4

    Indian Academy of Sciences (India)

    The crystal structures of these phosphors were characterized by powder X-ray diffraction, and the luminescent properties of Eu3+-, Li+-codoped CaWO4 were investigated by diffuse reflectance spectra, photoluminescence emission spectra, photoluminescence excitation spectra, and the Commission International de L' ...

  11. 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

  12. 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.

  13. Thermally induced evolution of sol–gel grown WO3 films on ITO/glass substrates

    NARCIS (Netherlands)

    Caruso, T.; Castriota, M.; Policicchio, A.; Fasanella, A.; Santo, M.P. De; Ciuchi, F.; Desiderio, G.; Rosa, S. La; Rudolf, P.; Agostino, R.G.; Cazzanelli, E.

    2014-01-01

    The electronic, morphological and structural properties of WO3 thin films, synthesized via a sol-gel route and deposited on ITO/glass substrates by spin-coating, were analyzed as a function of annealing temperature (100-700 degrees C range) by Scanning Electron Microscopy, Atomic Force Microscopy,

  14. 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.

  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. 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.

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

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 36; Issue 1. Synthesis and characterization of MoO3–WO3 composite thin films by liquid phase deposition technique: Investigation of its photochromic properties. H M Farveez Ahmed Noor Shahina Begum. Volume 36 Issue 1 February 2013 pp 45-49 ...

  18. WoSIS: providing standardised soil profile data for the world

    NARCIS (Netherlands)

    Batjes, N.H.; Carvalho Ribeiro, E.D.; Oostrum, van A.J.M.; Leenaars, J.G.B.; Hengl, T.; Mendes de Jesus, J.S.

    2017-01-01

    The aim of the World Soil Information Service (WoSIS) is to serve quality-assessed, georeferenced soil data (point, polygon, and grid) to the international community upon their standardisation and harmonisation. So far, the focus has been on developing procedures for legacy point data with special

  19. Alkali-Phosphate Glasses Containing WO3 and Nb2O5

    Directory of Open Access Journals (Sweden)

    L. Bih

    2013-01-01

    Full Text Available New phosphate glasses in the quaternary system (50-x A2O-x WO3-10 Nb2O5-40 P2O5, with x = 0; 30 and A = Li or Na were prepared by the melt quenching method. The effect on the crystallization behaviour of the glass due to the introduction of WO3 into the glass composition and, consequently, the diminishing of the molar amount of the alkaline oxide and the decreasing of the molar ratio between network modifiers and network formers (M/F was studied. The prepared glasses were heat-treated in air, at 550°C, 600°C, and 650°C for 4 hours. The structure, of the obtained samples, was studied by differential thermal analysis (DTA, X-ray powder diffraction (XRD, and Raman spectroscopy and the morphology by scanning electron microscopy (SEM. It was found that the replacement of Li2O or Na2O by WO3 reduces the number of the crystallised phases. In the lithium-niobiophosphate glasses, the presence of WO3 promotes the formation of NbOPO4 instead of the LiNbO3 phase and reduces the formation of ortho- and pyro-phosphate phases. The thermal treatments affect the arrangements of the network structure of the AW40-glasses.

  20. 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

  1. Ultrasmall Biocompatible WO3- x Nanodots for Multi-Modality Imaging and Combined Therapy of Cancers.

    Science.gov (United States)

    Wen, Ling; Chen, Ling; Zheng, Shimin; Zeng, Jianfeng; Duan, Guangxin; Wang, Yong; Wang, Guanglin; Chai, Zhifang; Li, Zhen; Gao, Mingyuan

    2016-07-01

    Ultrasmall biocompatible WO3 - x nanodots with an outstanding X-ray radiation sensitization effect are prepared, and demonstrated to be applicable for multi-modality tumor imaging through computed tomography and photoacoustic imaging (PAI), and effective cancer treatment combining both photothermal therapy and radiation therapy. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Electrical and optical properties of ZnO–WO3 nanocomposite and its ...

    Indian Academy of Sciences (India)

    DOI 10.1007/s12034-017-1373-5. Electrical and optical properties of ZnO–WO3 nanocomposite and its application as a solid-state humidity sensor. VANDNA SHAKYA. ∗. , N K PANDEY, SUNEET KUMAR MISRA and AKASH ROY. Sensors and Materials Research Laboratory, Department of Physics, University of Lucknow, ...

  3. 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.

  4. 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.

  5. 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.

  6. Mesoporous nanoplate multi-directional assembled Bi2WO6for high efficient photocatalytic oxidation of NO.

    Science.gov (United States)

    Wan, Jun; Du, Xiao; Wang, Ruimiao; Liu, Enzhou; Jia, Jia; Bai, Xue; Hu, Xiaoyun; Fan, Jun

    2018-02-01

    Herein, a mesoporous nanoplate multi-directional assembled Bi 2 WO 6 architecture was successfully prepared and applied for the photocatalytic removal of NOx pollutants at low concentrations under visible light and simulated solar light irradiation. Bi 2 WO 6 -180-C synthesized at a hydrothermal temperature of 180 °C with calcination exhibited an excellent conversion efficiency in the photocatalytic oxidation of gaseous NO. The crystallinity, morphology, specific surface area, pore environment, light absorption, and separation of photogenerated electrons and holes were investigated by various techniques; the excellent photocatalytic performance of Bi 2 WO 6 -180-C was attributed to its special hierarchical mesoporous structure with an appropriate pore size and interconnected porous network, which imparted good gas permeability and fast mass transfer of reaction intermediates and final products of NO oxidation. Furthermore, hierarchical mesoporous Bi 2 WO 6 showed excellent photocatalytic durability and reusability. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. 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.

  8. 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

  9. 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...

  10. Enhanced photocatalytic activity of Bi2WO6/TiO2 composite coated polyester fabric under visible light irradiation

    Science.gov (United States)

    Du, Zoufei; Cheng, Cheng; Tan, Lin; Lan, Jianwu; Jiang, Shouxiang; Zhao, Ludan; Guo, Ronghui

    2018-03-01

    In this study, a visible-light-driven photocatalyst Bi2WO6/TiO2 composite was reported using one-step hydrothermal method and then coated on the polyester fabric. The samples were systematically characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, UV-vis diffuse reflection spectroscopy and photoluminescence spectroscopy (PL). The photocatalytic activity of Bi2WO6/TiO2 coated polyester fabric was evaluated by degradation of Rhodamine B (RhB) and Methylene blue (MB) under visible light irradiation. The self-cleaning property of the fabrics was assessed through removing red wine stain. The results reveal that the Bi2WO6/TiO2 composites with irregular shape are coated on the polyester fabric successfully. The UV-vis absorption spectra show a broad absorption band in the visible region, which extends the scope of absorption spectrum and helps to improve the photocatalytic degradation efficiency. Photocatalytic activities of the Bi2WO6/TiO2 composite polyester fabric are associated with the content of TiO2. Bi2WO6/15%TiO2 coated polyester fabric exhibits the degradation efficiency for RhB and MB up to 98% and 95.1%, respectively, which is much higher than that of pure Bi2WO6 and TiO2 coated polyester fabric. Moreover, Bi2WO6/15%TiO2 coated polyester fabric shows good cycle stability toward continuous three cycles of photocatalytic experiment for dyes degradation. In addition, the Bi2WO6/TiO2 coated polyester fabric shows good self-cleaning property. This work could be extended to design of other composite photocatalyst coating on the fabric for enhancing activity by coupling suitable wide and narrow band-gap semiconductors.

  11. 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.

  12. 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.

  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. 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.

  16. Graphitic g-C{sub 3}N{sub 4}-WO{sub 3} Composite: Synthesis and Photocatalytic Properties

    Energy Technology Data Exchange (ETDEWEB)

    Doan, An Tran; Thi, Xuan Dieu Nguyen; Nguyen, Phi Hung; Thi, Viet Nga Nguyen; Vo, Vien [Quy Nhon Univ., Quy Nhon (Viet Nam); Kim, Sung Jin [Ewha Womans Univ., Seoul (Korea, Republic of)

    2014-06-15

    Graphitic g-C{sub 3}N{sub 4}-WO{sub 3} composite was synthesized simply by decomposing melamine in the presence of WO{sub 3} at 500 .deg. C. The obtained material was characterized by XRD, SEM, IR and XPS. The results showed that the as-prepared composite exhibits orthorhombic WO{sub 3} phase coated by g-C{sub 3}N{sub 4} and the g-C{sub 3}N{sub 4} decomposed completely with N-doped WO{sub 3} remaining at elevated calcination temperatures. The photocatalytic activity of the composite was evaluated by the photodegradation of methylene blue under visible light. An enhancement in photocatalytic activity for the graphitic g-C{sub 3}N{sub 4}-WO{sub 3} composite compared to the conventional nitrogen-doped WO{sub 3} was observed, which can be attributed to the presence of g-C{sub 3}N{sub 4} in the material.

  17. Subsolidus phase relations in the ZnO-WO{sub 3}-Bi{sub 2}O{sub 3} system

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yandi [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Chen Dagui, E-mail: chendg@fjirsm.ac.cn [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Pan Danmei; Tang Yuhuan; Liu Weizhen [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Huang Feng, E-mail: fhuang@fjirsm.ac.cn [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

    2011-01-12

    Research highlights: In order to search for suitable flux to grow ZnO single crystals, the subsolidus phase relations of the ternary system ZnO-WO{sub 3}-Bi{sub 2}O{sub 3} and the phase diagram of ZnO-Bi{sub 2}WO{sub 6} pseudo-binary system were investigated. The results reveal that the Bi{sub 2}WO{sub 6} might not be the suitable flux for ZnO crystal growth below 1250 deg. C. - Abstract: The subsolidus phase relations of the ternary system ZnO-WO{sub 3}-Bi{sub 2}O{sub 3} were investigated by means of X-ray diffraction (XRD). Six binary compounds and seven 3-phase regions were determined, and no ternary compounds were found in this ternary system. The phase diagram of pseudobinary system ZnO-Bi{sub 2}WO{sub 6} was also constructed through XRD and differential thermal analysis (DTA) methods, which forms eutectic system with eutectic temperature about 945 deg. C, the corresponding eutectic component is 35 mol% ZnO and 65 mol% Bi{sub 2}WO{sub 6}.

  18. 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}.

  19. 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)

  20. Facile synthesis of 2-D Cu doped WO3 nanoplates with structural, optical and differential anti cancer characteristics

    Science.gov (United States)

    Mehmood, Faisal; Iqbal, Javed; Gul, Asma; Ahmed, Waqqar; Ismail, M.

    2017-04-01

    Simple chemical co-precipitation method has been employed to synthesize two dimensional copper (Cu) doped tungsten oxide (WO3) nanoplates. A numbers of characterization techniques have been used to investigate their structural, optical and biocompatible anti cancer properties. The XRD results have confirmed the monoclinic crystal structure of WO3 nanoplates, and also successful doping of Cu ions into the WO3 crystal lattice. The presence of functional groups and chemical bonding have been verified through FTIR and Raman spectroscopy. The SEM images demonstrate that both undoped and Cu doped WO3 samples have squares plate like morphology. The EDX spectra confirm the presence of Cu, W and O ions. Diffuse reflectance spectroscopy (DRS) analysis has revealed a substantial red-shift in the absorption edge and a decrease in the band gap energy of nanoplates with Cu doping. Photoluminescence spectroscopy has been used to study the presence of defects like oxygen vacancies. Furthermore, the differential cytotoxic properties of Cu doped WO3 samples have been evaluated against human breast (MCF-7) and liver (Hep-2) cancer cells with ectocervical epithelial (HECE) healthy cells. The present findings confirm that the Cu doped WO3 nanoplates can be used as an efficient biocompatible anti cancer agent.

  1. Origin of TSL peaks located at 200-250 K in UV-irradiated PbWO4 crystals

    International Nuclear Information System (INIS)

    Fabeni, P.; Krasnikov, A.; Laguta, V.V.; Nikl, M.; Pazzi, G.P.; Susini, C.; Zazubovich, S.

    2007-01-01

    Thermally stimulated luminescence (TSL) was studied for many PbWO 4 crystals after their selective irradiation at 80-220 K in the 3.4-5.0 eV energy range to clarify the origin of the defects responsible for the TSL peaks located in the 200-250 K range. The conclusion is made that both in PbWO 4 and PbWO 4 :Mo crystals the total TSL intensity and the intensity ratio of various TSL peaks are mainly determined by the concentration and type of oxygen and lead vacancies which depend on the crystal preparation and annealing conditions and on the concentration of trivalent rare-earth impurity ions. The TSL peak near 200 K is ascribed to {Pb + -WO 3 } centers and the peak in the 210-230 K range, to the electron centers, containing oxygen vacancies of the type of WO 2 and WO. Only the 250 K peak arises from electron MoO 4 3- centers. Thermally stimulated processes are accompanied with the green G(II) emission

  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. Judd–Ofelt analysis of spectroscopic properties of Eu3+:KLu(WO4)2 crystal

    International Nuclear Information System (INIS)

    Loiko, P.A.; Dashkevich, V.I.; Bagaev, S.N.; Orlovich, V.A.; Mateos, X.; Serres, J.M.; Vilejshikova, E.V.; Yasukevich, A.S.; Yumashev, K.V.; Kuleshov, N.V.; Dunina, E.B.; Kornienko, A.A.; Vatnik, S.M.; Pavlyuk, A.A.

    2015-01-01

    We report on a comprehensive spectroscopic study of monoclinic Eu:KLu(WO 4 ) 2 crystal concerning its potential applications in red lasers. Optical absorption and stimulated-emission cross-section spectra are determined for this crystal for the principal light polarizations, E || N p , N m and N g . The maximum σ SE corresponding to the 5 D 0 → 7 F 4 transition is 1.78×10 −20 cm 2 at 703.5 nm (for E || N m ). Spectroscopic properties of Eu:KLu(WO 4 ) 2 are modeled within the conventional Judd–Ofelt theory, as well as its modification for systems with an anomalously strong configuration interaction (ASCI), yielding absorption oscillator strengths, luminescence branching ratios for 5 D J → 7 F J' transitions and radiative lifetimes of the 5 D J states. Photoluminescent properties of Eu:KLu(WO 4 ) 2 are studied under UV/visible excitation. Polarized Raman spectra are measured for Eu:KLu(WO 4 ) 2 . - Highlights: • Top-seeded solution growth of Eu:KLu(WO 4 ) 2 monoclinic crystal. • Modeling of spectroscopic parameters with modified Judd–Ofelt theory. • Polarization-resolved absorption and stimulated-emission cross-section spectra. • Maximum stimulated-emission cross-section is 1.78×10 −20 cm 2 at 703.5 nm. • Polarized Raman spectroscopy of Eu:KLu(WO 4 ) 2 crystal.

  4. High-performance complementary electrochromic device based on WO3·0.33H2O/PEDOT and prussian blue electrodes

    Science.gov (United States)

    Yue, Yanfang; Li, Haizeng; Li, Kerui; Wang, Jinmin; Wang, Hongzhi; Zhang, Qinghong; Li, Yaogang; Chen, Pei

    2017-11-01

    The device assembly plays an important role in affecting the electrochromic (EC) performance of an electrochromic device (ECD). Here, WO3·0.33H2O films are fabricated by a hydrothermal method and then PEDOT:PSS are spin-coated on the surface of WO3·0.33H2O films. Finally, the WO3·0.33H2O/PEDOT films are assembled with electrodeposited prussian blue (PB) to fabricate the WO3·0.33H2O/PEDOT-PB complementary electrochromic devices (ECDs). Compared with pure WO3·0.33H2O and WO3·0.33H2O/PEDOT single-active-layer structure ECDs, the complementary ECD exhibits higher optical modulation, higher coloration efficiency and faster response time, which would provide a promising platform for energy-saving smart (ESS) window.

  5. Investigation of multiferroic properties in MnWO{sub 4} by SHG-spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Maringer, Michael; Meier, Dennis; Lottermoser, Thomas; Yuan, Gouliang; Fiebig, Manfred [HISKP, Universitaet Bonn (Germany); Becker, Petra; Bohaty, Ladislav [Institut fuer Kristallographie, Universitaet zu Koeln (Germany)

    2008-07-01

    Magnetoelectric multiferroics, i.e. compounds displaying magnetic and ferroelectric order in the same phase, attract considerable attention from the point of view of potential device application as well as fundamental physics. In the so-called spin-spiral compounds the interaction is particularly pronounced. Here we introduce optical second harmonic generation (SHG) as a powerful tool for the study of magnetic and eletronic properties and their magnetoelectric interaction in spin-spiral compounds, taking MnWO{sub 4} as an example. SHG gives detailed information about the symmetry of crystalline phases and about symmetry changes caused by phase transitions. In particular, in MnWO{sub 4} the (anti)ferromagnetic incommensurate phase and the magnetically induced ferroelectric, state are investigated. Although the magnetically induced spontaneous polarization is about four orders of magnitude weaker than in a conventional ferroelectric, a pronounced SHG signal is obtained.

  6. Time resolved measurements of the multiferroic switching in MnWO4

    Energy Technology Data Exchange (ETDEWEB)

    Baum, Max; Finger, Thomas; Braden, Markus [II. Physikalisches Institut, Universitaet Koeln (Germany); Leist, Jeannis [Institut fuer Physikalische Chemie, Georg-August-Universitaet Goettingen (Germany); Schmalzl, Karin [Juelich Centre for Neutron Science (JCNS), ILL, Grenoble (France); Regnault, Louis-Pierre [Institut Nanosciences et Cryogenie, CEA-Grenoble (France); Becker, Petra; Bohaty, Ladislav [Institut fuer Kristallographie, Universitaet Koeln (Germany)

    2011-07-01

    Multiferroic materials or compounds with a strong magnetoelectric effect posses a large application potential in data storage techniques. Quite recently, systems with a peculiar spiral magnetic order were shown to directly induce a spontaneous electric polarisation and to exhibit giant magnetoelectric and magnetocapacitance effects, among them MnWO4. Neutron scattering with spherical polarisation analysis gives direct access to the chiral component of the magnetic structure which is directly linked to the electric polarisation and thus may be tunable by an electric field. In MnWO4 it is possible to drive multiferroic hysteresis loops at constant temperature as a function of the electric field. We broadened our investigations in this topic and present time resolved measurements of magnetoelectric switching. We applied stroboscopic techniques in order to investigate how fast the chiral component of the magnetic structure adapts to an instantaneously switched electric field. The time scale of the response is remarkable slow, in the range of 3 - 20 ms.

  7. Polarization-dependent X-ray absorption spectroscopy of MnWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Hollmann, Nils; Hu, Zhiwei; Tjeng, Liu Hao [II. Physikalisches Institut, Universitaet zu Koeln (Germany); Bohaty, Ladislav; Becker-Bohaty, Petra [Kristallographisches Institut, Universitaet zu Koeln (Germany); Tanaka, Arata [Department of Quantum Matter, Hiroshima University (Japan)

    2008-07-01

    Multiferroic materials which combine magnetism and ferroelectricity currently attract considerable attention. One of the recently discovered multiferroic materials is MnWO{sub 4} (Huebnerite). It belongs to the group of multiferroics where a spontaneous electric polarization is caused by a spiral magnetic structure with a spin rotation axis not coinciding with the propagation vector. To investigate the details of this astonishing combination of electronic and magnetic properties, we look at the electronic structure with the use of polarization-dependent X-ray absorption spectroscopy on single crystals of MnWO{sub 4}. The analysis of the experimental data on the L-edge of Mn is done by a configuration interaction calculation and is discussed.

  8. Coexistence of ferroelectric and long-wavelength magnetic ordering in MnWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Meier, Dennis; Maringer, Michael; Lottermoser, Thomas; Yuan, Gouliang; Fiebig, Manfred [HISKP, Universitaet Bonn (Germany); Becker, Petra; Bohaty, Ladislav [Institut fuer Kristallographie, Universitaet zu Koeln (Germany)

    2008-07-01

    The strong interest in magnetoelectric multiferroics is due to their potential concerning the design of novel multifunctional devices, as well as to their unusual physical properties. Among these, TbMnO{sub 3}, Ni{sub 3}V{sub 2}O{sub 8}, and MnWO{sub 4} form a particularly challenging group: The key factor for ferroelectricity lies in the long-wavelength magnetic order. However, the nature of the ferroelectric (FE) state in such a spiral magnet and its relation to the magnetic ordering is largely unclear. Here we report about the spatial distribution of FE domains in MnWO{sub 4}, revealed by optical second harmonic generation (SHG). Although the spontaneous polarization in this ferroelectric is magnetically induced, 180 domains as in a conventional ferroelectric are observed.

  9. Synthesis and characterization of WO{sub 3} nanostructures prepared by an aged-hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Huirache-Acuna, R., E-mail: rafael_huirache@yahoo.it [CFATA-UNAM, Boulevard Juriquilla 3001, Juriquilla Queretaro, 76230 (Mexico); Universidad La Salle Morelia, Av. Universidad 500, Mpio. Tarimbaro Mich., 58880 (Mexico); Paraguay-Delgado, F. [Centro de Investigacion en Materiales Avanzados, S.C. CIMAV, Laboratorio Nacional de Nanotecnologia-Chihuahua, Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chih., 31109 (Mexico); Albiter, M.A.; Lara-Romero, J. [Facultad de Ingenieria Quimica, Universidad Michoacana de San Nicolas de Hidalgo, Morelia Mich., 58000 (Mexico); Martinez-Sanchez, R. [Centro de Investigacion en Materiales Avanzados, S.C. CIMAV, Laboratorio Nacional de Nanotecnologia-Chihuahua, Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chih., 31109 (Mexico)

    2009-09-15

    Nanostructures of tungsten trioxide (WO{sub 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{sub BET}) were measured by using the BET method. The lengths of the WO{sub 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.

  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. Study of vibrational spectra of beta-LiYb(WO4)2

    International Nuclear Information System (INIS)

    Kondratov, O.I.; Efremov, V.A.; Petrov, K.I.; Fomichev, V.V.

    1978-01-01

    The Raman and infrared absorption spectra (up to 30 cm -1 ) of β-Li Yb(WO 4 ) 29 and a spectrum of an isotope-substituted, with respect to lithium, sample have been measured. Frequencies and shapes of normal vibration of two non-equivalent crystal directions have been calculated in a polymer approximation. The system of force constants has been determined. The frequency branches of the vibrations have been calculated when a phase vector changes from S=1 to 100 and atoms displacements. The calculation results have shown that a considerable contribution to the vibrations of end W-O bonds (the region of 900-930 cm -1 ) is made by the coordinates of the n-O bonds (where M is Li or Yb) elongation and by deformation of the WOM and OMO angles

  12. In situ microscopy of rapidly heated nano-Al and nano-Al/WO3 thermites

    International Nuclear Information System (INIS)

    Sullivan, Kyle T.; Zachariah, Michael R.; Chiou, Wen-An; Fiore, Richard

    2010-01-01

    The initiation and reaction mechanism of nano-Al and nano-Al thermites in rapid heating environments is investigated in this work. A semiconductor-based grid/stage was used, capable of in situ heating of a sample from room temperature to 1473 K, and at a rate of 10 6 K/s, inside an electron microscope. Nano-Al was rapidly heated in a transmission electron microscope, and before and after images indicate that the aluminum migrates through the shell, consistent with a diffusion-based mechanism. A nano-Al/WO 3 composite was then heated in a scanning electron microscope. The results indicate that a reactive sintering mechanism is occurring for the nano-Al/WO 3 thermite, as the products are found to be in surface contact and significantly deformed after the heating pulse.

  13. Formation of W/O microemulsion based on natural glycolipid biosurfactant, mannosylerythritol lipid-a.

    Science.gov (United States)

    Worakitkanchanakul, Wannasiri; Imura, Tomohiro; Morita, Tomotake; Fukuoka, Tokuma; Sakai, Hideki; Abe, Masahiko; Rujiravanit, Ratana; Chavadej, Sumaeth; Kitamoto, Dai

    2008-01-01

    Mannosylerythritol lipid-A (MEL-A) is a glycolipid biosurfactant abundantly produced from soybean oil by microorganisms at a yield of up to 100 g/L. In this study, the formation of water-in-oil (W/O) microemulsion based on the single component of MEL-A was confirmed using dynamic light scattering (DLS) and freeze fracture electron microscopy (FF-EM). DLS and FF-EM measurements revealed that the diameter of the microemulsion increases with an increase in water-to-surfactant mole ratio (W(0)) ranging from 20 to 60 nm, and the maximum W(0) value was found to be 20, which is as high as that of soybean lecithin. Glycolipid biosurfactant has a great potential for the formation of W/O microemulsion without using any cosurfactants.

  14. A New Hydrogen Sensor Based on SNS Fiber Interferometer with Pd/WO3 Coating

    Directory of Open Access Journals (Sweden)

    Jinxin Shao

    2017-09-01

    Full Text Available This paper presents a new hydrogen sensor based on a single mode–no core–single mode (SNS fiber interferometer structure. The surface of the no core fiber (NCF was coated by Pd/WO3 film to detect the variation of hydrogen concentration. If the hydrogen concentration changes, the refractive index of the Pd/WO3 film as well as the boundary condition for light propagating in the NCF will all be changed, which will then cause a shift into the resonant wavelength of interferometer. Therefore, the hydrogen concentration can be deduced by measuring the shift of the resonant wavelength. Experimental results demonstrated that this proposed sensor had a high detection sensitivity of 1.26857 nm/%, with good linearity and high accuracy (maximum 0.0055% hydrogen volume error. Besides, it also possessed the advantages of simple structure, low cost, good stability, and repeatability.

  15. Red Eu,Yb:KY(WO4)2 laser at ∼702 nm

    International Nuclear Information System (INIS)

    Dashkevich, V I; Orlovich, V A; Bui, A A; Bagayev, S N; Vatnik, S M; Loiko, P A; Yumashev, K V; Yasukevich, A S; Kuleshov, N V; Pavlyuk, A A

    2015-01-01

    In this letter, laser operation is demonstrated with a Eu,Yb: KY(WO 4 ) 2 crystal on the 5 D 0   →   7 F 4 transition of the Eu 3+ ion. When pumping into the 7 F 1   →   5 D 1 absorption band by a diode-pumped Nd 3+ :KGd(WO 4 ) 2 /KTP laser power-scaled at 533.6 nm up to a watt-level, we achieved 2.5 mW of the continuous wave (CW) red output at ∼702.1 nm. At quasi-CW pumping with a duty cycle of 10%, the peak power of the ms-long pulses arrived at ∼19 mW, corresponding to a green-to-red conversion efficiency of 0.8%. (letter)

  16. A hierarchically porous anatase TiO2 coated-WO3 2D IO bilayer film and its photochromic properties.

    Science.gov (United States)

    Li, Hua; Wu, Huazhong; Xiao, Jiajia; Su, Yanli; Robichaud, Jacques; Brüning, Ralf; Djaoued, Yahia

    2016-01-18

    A hierarchically porous anatase TiO2 coated-WO3 2D inverse opal (IO) bilayer film was fabricated on ITO glass using a layer by layer route with a hierarchically porous TiO2 top layer and an ordered super-macroporous WO3 2D IO bottom layer. This novel TiO2 coated-WO3 2D IO bilayer film was evaluated for photochromic applications.

  17. 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.

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

    Indian Academy of Sciences (India)

    H M Farveez Ahmed and Noor Shahina Begum technique. The precursor solution for deposition of MoO3–. WO3 was prepared by dissolving Mo (99·9% pure, Fluka chemicals) and W (99·9%, Aldrich chemicals) powder sepa- rately in 30% ice-cold solution of H2O2 and acetic acid. The reaction mixtures were kept overnight ...

  19. Growth of ultra radiation hard NaBi(WO4)2 single crystal

    International Nuclear Information System (INIS)

    Govind Singh, S.; Tyagi, Mohit; Singh, Awadh K.; Sangeeta

    2009-01-01

    Single crystals of undoped NaBi(WO 4 ) 2 were grown under different condition by Czochralski technique. Radiation hardness of the crystals was studied by irradiating them up to 10''5 and 10''6 Gy dose at a fast rate (2 Gy/sec) using 60 Co as a gamma source. Transmission spectra of the crystal samples were recorded and analyzed. It is found that crystal grown from recrystalized charge shows very good optical quality and excellent radiation hardness. (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. Controlled synthesis and structure characterization of nanostructured MnWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Hu, W.B., E-mail: w.hu@tom.com [Hubei Institute for Nationalities, Enshi 445000 (China); Nie, X.L.; Mi, Y.Zh. [Hubei Institute for Nationalities, Enshi 445000 (China)

    2010-01-15

    Using Mn to partly substitute the W in W{sub 18}O{sub 49} nanowires, the synthesis of MnWO{sub 4} hubnerite nano-cocoons is described in this paper, by using mixed MnCl{sub 2} and WCl{sub 6} as the precursors and cyclohexanol as the solvent, in a simple solvothermal process. Detailed characterization of the resulting products, using electron microscopy and spectroscopy, has shown that the gradual increase of MnCl{sub 2} concentration changes the long W{sub 18}O{sub 49} nanowires to cocoon-like nanomaterials of stable MnWO{sub 4} phase. The driving force for such transformations is attributed to the Mn{sup 2+} inclusion within the W{sub 18}O{sub 49}. At low Mn{sup 2+} concentration, internal stresses would be introduced to the W{sub 18}O{sub 49} nanowires; whilst at high Mn{sup 2+} concentration close to the stoichiometric composition of MnWO{sub 4}, the formation of the nano-cocoons is triggered by the intrinsic crystalline feature of the hubnerite. It is believed that a combination of the initial nanowire nucleation and competing growth, and of self-assembly of neighboring parallel nanowires, leads to the final structure.

  2. Controlled synthesis and structure characterization of nanostructured MnWO4

    International Nuclear Information System (INIS)

    Hu, W.B.; Nie, X.L.; Mi, Y.Zh.

    2010-01-01

    Using Mn to partly substitute the W in W 18 O 49 nanowires, the synthesis of MnWO 4 hubnerite nano-cocoons is described in this paper, by using mixed MnCl 2 and WCl 6 as the precursors and cyclohexanol as the solvent, in a simple solvothermal process. Detailed characterization of the resulting products, using electron microscopy and spectroscopy, has shown that the gradual increase of MnCl 2 concentration changes the long W 18 O 49 nanowires to cocoon-like nanomaterials of stable MnWO 4 phase. The driving force for such transformations is attributed to the Mn 2+ inclusion within the W 18 O 49 . At low Mn 2+ concentration, internal stresses would be introduced to the W 18 O 49 nanowires; whilst at high Mn 2+ concentration close to the stoichiometric composition of MnWO 4 , the formation of the nano-cocoons is triggered by the intrinsic crystalline feature of the hubnerite. It is believed that a combination of the initial nanowire nucleation and competing growth, and of self-assembly of neighboring parallel nanowires, leads to the final structure.

  3. Composite WO3/TiO2 nanostructures for high electrochromic activity.

    Energy Technology Data Exchange (ETDEWEB)

    Reyes, Karla Rosa; Stephens, Zachary Dan.; Robinson, David B.

    2013-05-01

    A composite material consisting of TiO2 nanotubes (NTs) with WO3 electrodeposited homogeneously on its surface has been fabricated, detached from its substrate, and attached to a fluorine-doped tin oxide film on glass for application to electrochromic (EC) reactions. A paste of TiO2 made from commercially available TiO2 nanoparticles creates an interface for the TiO2 NT film to attach to the FTO glass, which is conductive and does not cause solution-phase ions in an electrolyte to bind irreversibly with the material. The effect of NT length on the current density and the EC contrast of the material were studied. The EC redox reaction seen in this material is diffusion- limited, having relatively fast reaction rates at the electrode surface. The composite WO3/TiO2 nanostructures showed higher ion storage capacity, better stability, enhanced EC contrast and longer memory time compared with the pure WO3 and TiO2.

  4. Visualization of X-ray Beam Using CdWO4 Crystal for Macromolecular Crystallography

    Directory of Open Access Journals (Sweden)

    Kazimierz J. Gofron

    2011-12-01

    Full Text Available In synchrotron diffraction experiments, it is typically assumed that the X-ray beam at the sample position is uniform, stable and has dimensions that are controlled by the focus and slits settings. As might be expected, this process is much more complex. We present here an investigation of the properties of a synchrotron X-ray beam at the sample position. The X-ray beam is visualized with a single crystal scintillator that converts X-ray photons into visible light photons, which can be imaged using Structure Biology Center (SBC on-axis and off-axis microscope optics. The X-ray penetration is dependent on the composition of the scintillator (especially the effective Z, and X-ray energy. Several scintillators have been used to visualize X-ray beams. Here we compare CdWO4, PbWO4, Bi4Ge3O12, Y3Al5O12:Ce (YAG:Ce, and Gd2O2S:Tb (phosphor. We determined that scintillator crystals made of CdWO4 and similar high-Z materials are best suited for the energy range (7–20 keV and are most suitable for beam visualization for macromolecular crystallography applications. These scintillators show excellent absorption, optical, and mechanical properties.

  5. Spin orbit torques in W(O) based three terminal magnetic memory devices

    Science.gov (United States)

    Zhang, Jie; Phung, Timothy; Garg, Chirag; Rettner, Charles; Hughes, Brian. P.; Yang, See-Hun; Parkin, Stuart. S. P.

    Recently, there has been a large interest in using spin orbit torques to controllably manipulate the magnetic order parameter in several promising magnetic memory devices such as racetrack memory and spin transfer torque MRAM. The efficient operation of such devices necessitates the finding of materials which exhibit efficient conversion of charge currents to spin orbit torques. This is typically quantified by the so-called spin Hall angle. The most efficient spin orbit torque generator to date based on the use of conventional metallic materials is W(O), wherein the effective spin hall angle is found to be -0.5. Here, we explore the use of W(O) to manipulate magnetization in three terminal magnetic memory devices. We find, consistent with the large spin orbit torques, observed in W(O), that the critical current required for switching a magnetic element is significantly smaller than compared to other metallic systems such as Pt, β-W, and Ta. Lastly, we shall discuss the technologically important high speed ( ns time scale) switching dynamics in these devices and the role of complex micromagnetic states upon the switching process.

  6. Carbon materials as additives to WO3 for an enhanced conversion of simulated solar light

    Directory of Open Access Journals (Sweden)

    Rocío Jiménez Carmona

    2016-02-01

    Full Text Available We have explored the impact of the incorporation of nanoporous carbons as additives to tungsten oxide on the photocatalytic degradation of two recalcitrant pollutants: rhodamine B and phenol, under simulated solar light. For this purpose, WO3/carbon mixtures were prepared using three carbon materials with different properties (in terms of porosity, structural order and surface chemistry. Despite the low carbon content used (2 wt. %, a significant increase in the photocatalytic performance of the semiconductor was observed for all the catalysts. Moreover, the influence of the carbon additive on the performance of the photocatalysts was found to be very different for the two pollutants. Carbon additives of hydrophobic nature increased the photodegradation yield of phenol compared to bare WO3, likely due to the higher affinity and stronger interactions of phenol molecules towards basic nanoporous carbons. Oppositely, the use of acidic carbon additives led to higher rhodamine B conversions due to increased acidity of the WO3/carbon mixtures and the stronger affinity of the pollutant for acidic catalyst’s surfaces. As a result, the photooxidation of rhodamine B is favored by means of a coupled (photosensitized and photocatalytic degradation mechanism. All these results highlight the importance of favoring the interactions of the pollutant with the catalyst’s surface through a detailed design of the features of the photocatalyst.

  7. A beam test of PbWO sub 4 Cherenkov radiators

    CERN Document Server

    Kobayashi, M; Yoshimura, Y; Komatsubara, T K; Mimori, K; Omata, K; Sekiguchi, T; Tsunemi, T; Yoshioka, T; Tamagawa, Y; Shirasaka, H; Fujiwara, T; Usuki, Y; Ishii, M

    2002-01-01

    PbWO sub 4 heavily doped with trivalent rare-earth ions like La sup 3 sup + , Gd sup 3 sup + , Y sup 3 sup + , etc. has recently been proposed as an excellent new, heavy and radiation-hard Cherenkov radiator, and the upper limit of the remaining scintillation light yield (LY) was obtained from measurement of radioisotope gamma-rays. Since then, we have made a quantitative study of the remaining scintillation LY using a 0.5-1 GeV/c pi sup + /p/d beam. Compared with a standard PbWO sub 4 : Gd(80 at ppm) scintillator, the scintillation LY is quenched to 4.8%, 6.0%, and 11.6% for La sup 3 sup + concentration of 8 at%, La sup 3 sup + of 5 at% and Gd sup 3 sup + of 3 at%, respectively. The scintillation LY remaining in PbWO sub 4 : La(8 at%) was as weak as 15% of the Cherenkov LY for relativistic charged particles.

  8. 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.

  9. Controllable topological transformation from BiOCl hierarchical microspheres to Bi{sub 2}WO{sub 6} superstructures in the Bi–W–Cl–O system

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Jiao [National Engineering Research Center for Manufacturing Equipment Digitization, Department of Mechanical Science and Engineering, Huazhong University of Science and Technology (HUST), No. 1037, Luoyu Road, Wuhan 430074 (China); State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Shi, Songxin, E-mail: shisx@hust.edu.cn [National Engineering Research Center for Manufacturing Equipment Digitization, Department of Mechanical Science and Engineering, Huazhong University of Science and Technology (HUST), No. 1037, Luoyu Road, Wuhan 430074 (China); Tang, Tengteng [State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Tian, Shouqin [State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Yang, Wenjuan [State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Zeng, Dawen [Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China)

    2015-09-15

    Graphical abstract: The three-dimensional (3D) Bi{sub 2}WO{sub 6} superstructures assembled by nanosheets were directly transformed topologically from BiOCl hierarchical microspheres via a facile one-pot solvothermal method. Furthermore, the crystal growth of Bi{sub 2}WO{sub 6} superstructure was confirmed to occur at the exposed plane (0 0 1) of BiOCl nanosheets with WO{sub 6}{sup 6−} units replacing the interlaminar Cl atoms. Their similar layered structures favored the controllable transformation of BiOCl to Bi{sub 2}WO{sub 6} through the substitution process. And this topological transformation may provide a new prospective to the synthesis of other 3D compounds. - Highlights: • Bi{sub 2}WO{sub 6} superstructures were prepared by topological transformation of BiOCl assembly. • Transformation process experienced three stages of BiOCl, BiOCl/Bi{sub 2}WO{sub 6} and Bi{sub 2}WO{sub 6}. • Bi{sub 2}WO{sub 6} superstructures grew at the exposed (0 0 1) facets of BiOCl nanosheets. • The growth mechanism was revealed from thermodynamic and kinetic dynamic aspects. - Abstract: In this work, three-dimensional (3D) Bi{sub 2}WO{sub 6} superstructures assembled by nanosheets were prepared using the topological transformation of BiOCl hierarchical microspheres via a facile one-pot solvothermal method. Interestingly, it was found that the transformation process experienced three stages including BiOCl, BiOCl/Bi{sub 2}WO{sub 6} composites and Bi{sub 2}WO{sub 6} with increasing solvothermal time at 150 °C, which was confirmed by X-Ray Diffraction (XRD), Raman spectrometer and Transmission Electron Microscopy (TEM) results. Importantly, the crystal growth of Bi{sub 2}WO{sub 6} superstructures occurred at the exposed (0 0 1) facets of BiOCl nanosheets with WO{sub 6}{sup 6−} units replacing the interlaminar Cl atoms. Also, the growth mechanism was revealed and discussed in the thermodynamic and kinetic dynamic aspects. Compared with BiOCl superstructures, the Bi

  10. 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%.

  11. 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).

  12. Study of heat exchange between air and snow block with a vertical hole. Effect of initial height of snow block on the characteristics of heat exchange; Enchokuko wo yusuru setsukai to kuki tono netsukokan ni kansuru kenkyu. Setsukai no shoki takasa ga reikyaku noryoku ni oyobosu eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Iijima, K. [Sanki Engineering Co. Ltd., Tokyo (Japan); Kobiyama, M.; Wang, A.R.; Hanaoka, Y.; Ito, Y. [Muroran Institute of Technology, Hokkaido (Japan)

    2000-01-25

    The authors proposed the snow cooling system of direct heat exchange between hot air and snow block with a vertical hole. In this snow cooling system, the characteristics of heat exchange is little affected by the amount of remaining snow, and the outlet air temperature is almost constant, and be enough low to use for the actual air conditioning system. So this system has become to be adopted widely. In this study, the authors investigated the effect of initial snow height on the characteristics of heat exchange by the experiment with models of practical scale. Experimental results showed that heat transfer coefficients on the snow surfaces of top and bottom plane were not affected by initial snow height, but the heat transfer coefficient of snow hole increased with decreasing snow height being affected by the entrance region. It was found that heat transfer coefficient of snow hole approached to a constant value on condition that snow height was over 2 meters. A empirical equation compensated by the initial height of snow block was obtained from the experimental results. (author)

  13. Study of heat exchange between air and snow block with a vertical hole. Effect of air flow rate on heat exchange characteristics; Enchokuko wo yusuru setsukai to kuki tono netsu kokan ni kansuru kenkyu. Kuki no ryuryo ga reikyaku noryoku ni oyobosu eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Iijima, K. [Sanki Engineering Co. Ltd., Tokyo (Japan); Kobiyama, M.; Wang, A.R.; Hanaoka, Y.; Kawamura, M. [Muroran Institute of Technology, Hokkaido (Japan)

    1999-08-25

    It is very important to use many kinds of natural energy resources to keep environment clean and to reduce the energy consumption. Many simple and skilful methods to utilize the natural energy have to be developed. The authors have been proposing to utilize snow stored till summer as one of the natural cold and clean energy resources. In this study, the authors investigated the characteristics of direct heat exchange between hot air and snow block with a vertical hole. This heat transfer model, so called as the snow cooling system, may he applied to various air-conditioning systems of conventional living room and so on. As the heat transfer process of this model is very complicated because the shape of the snow block changes by the progress of melting, the characteristics of -the direct heat exchange were investigated by the experiment with a model of practical scale. The outlet air temperature through the snow hole and snow melting process were measured for various air flow rates at constant inlet air temperature 30 degree C. Experimental results show that the outlet air temperature from the snow cooling system was almost constant and enough lower to use for the actual air conditioning situations. Heat transfer coefficients on the snow surfaces of top plane, bottom plane and side wall of the snow hole were clear by those experimental results, and the correlative equations between the overall Nusselt number and the Reynolds number are presented for three surfaces mentioned above. (author)

  14. Change of environmental factors in different site which effect the conversion efficiency of photovoltaic module. Comparison of the environmental factors in Shinjuku Tokyo with the one in Chino Nagano; Kotonaru chiten ni okeru taiyo denchi no henkan koritsu ni eikyo wo ataeru kankyo inshi no henka. Tokyoto Shinjukuku to Naganoken Chinoshi no kankyo inshi no hikaku

    Energy Technology Data Exchange (ETDEWEB)

    Higuchi, T.; Tani, T.; Hirata, Y.; Inasaka, T. [Science University of Tokyo, Tokyo (Japan)

    1997-11-25

    Environmental factors affecting conversion efficiency of solar cells were measured in Tokyo and Nagano to comparatively study the difference. In the study, measurement was made of intensity of global solar radiation on an inclined surface (insolation intensity), ambient air temperature, and distribution of spectral solar radiation at the two points. Also measured were output characteristics of polycrystal silicon solar cell modules and amorphous silicon solar cell modules. The result of the comparative analysis was as follows: The annual inclined global solar radiation amount integrated in 1996 is 27% more in Nagano than in Tokyo. The weighted average insolation intensity in Nagano is 0.09 kW/m{sup 2} higher in Tokyo. The weighted average cell temperature in Nagano is 4degC lower than in Tokyo. The effective spectral ratio in Nagano is 1-2% lower both in polycrystal Si and amorphous Si than in Tokyo. Thus, it was inferred from that environmental factors are different that conversion efficiencies of photovoltaic modules were different. 6 refs., 5 figs., 5 tabs.

  15. 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.

  16. 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.

  17. Dispersion of Cs0.33WO3 particles for preparing its coatings with higher near infrared shielding properties

    Science.gov (United States)

    Liu, Jingxiao; Xu, Qiang; Shi, Fei; Liu, Suhua; Luo, Jiayu; Bao, Lei; Feng, Xiang

    2014-08-01

    In order to achieve good dispersion of Cs0.33WO3 particles and improve their near-infrared (NIR) shielding efficiency, the influences of ball-milling and dispersant on the dispersion stability of Cs0.33WO3 particles and its near infrared shielding properties were investigated. The microstructure, morphology, particle size distribution and Zeta potential of the particle samples were characterized by XRD, SEM and laser particle size analyzer. The results indicate that adding appropriate dispersant after ball-milling is conducive to dispersion of Cs0.33WO3 powders. Polyvinyl alcohol and titanate coupling agent have better effects on the dispersion of Cs0.33WO3 colloidal solution than poly-carboxylic salt dispersant. Particularly, the as-prepared Cs0.33WO3 coatings prepared from colloidal dispersion solution using titanate coupling agent at pH = 7 showed best visible light transmittance and near-infrared shielding properties, and have great potential applications as thermal insulation coatings for building and automotive glasses.

  18. 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.

  19. 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.

  20. Response of the ABCG2 promoter in T47D cells and BeWo cells to sex hormone treatment.

    Science.gov (United States)

    Yasuda, Satoru; Kobayashi, Masaki; Itagaki, Shirou; Hirano, Takeshi; Iseki, Ken

    2009-09-01

    The aim of this study was to elucidate the effects of sex hormones on activity of the ABCG2 promoter in different cell lines. T47D cells and BeWo cells were used as models for ABCG2-expressing cell lines, and luciferase assays using ABCG2 promoter-luciferase constructs were performed. It was shown that progesterone increased the response of the ABCG2 promoter in T47D cells but not in BeWo cells. On the other hand, estradiol had no effect on response of the ABCG2 promoter in either cell line. However, response of the ABCG2 promoter was enhanced by overexpression of ERalpha in both T47D cells and BeWo cells. T47D cells had higher sensitivity to ERalpha than did BeWo cells. Furthermore, it was shown that the inductive effect of progesterone on the ABCG2 promoter was inhibited by addition of RU486 or mithramycin A. Therefore, it was thought that the ABCG2 promoter responded to stimulation of the progesterone receptor (PR)-Sp1 pathway in T47D cells. Furthermore, progesterone suppressed the response of the ABCG2 promoter by changing the expression levels of PR-A and PR-B in BeWo cells. These findings suggested that there are differences between cell lines in the regulation mechanism of ABCG2 expression by sex hormone treatment.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Novel synthesis of WO{sub 3} nanocrystals through pyrolytic decomposition of tungstate-based inorganic-organic hybrid nanobelts

    Energy Technology Data Exchange (ETDEWEB)

    Chen Deliang, E-mail: dlchen@zzu.edu.cn [School of Materials Science and Engineering, Zhengzhou University, 100 Science Road, Zhengzhou 450001 (China); Wen Hejing; Chen Huimin; Wang Hailong; Zhang Rui; Xu Hongliang; Yang Daoyuan; Lu Hongxia [School of Materials Science and Engineering, Zhengzhou University, 100 Science Road, Zhengzhou 450001 (China)

    2009-08-15

    The paper described a novel approach toward WO{sub 3} nanocrystals by pyrolytically decomposing tungstate-based inorganic-organic hybrid nanobelts in air at 500-600 deg. C for 2 h. The above-mentioned hybrid nanobelts were derived via a reaction of layered H{sub 2}W{sub 2}O{sub 7}.xH{sub 2}O and n-octylamine in a reverse-micelle-like medium (H{sub 2}W{sub 2}O{sub 7}.xH{sub 2}O/n-octylamine/heptane). The as-obtained WO{sub 3} nanocrystals and their intermediate products were characterized by the techniques of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM and FE-SEM), thermoanalysis (TG-DSC), Fourier-transform infrared spectra (FT/IR), UV-vis absorption and X-ray photoelectron spectroscopy (XPS). The as-obtained WO{sub 3} nanocrystals had an apparent size of 20-50 nm, and took on a loose-aggregate-like morphology. The WO{sub 3} nanocrystals derived via the pyrolytic decomposition process were almost separated from each other and could be redispersed readily, while the WO{sub 3} nanocrystals obtained by the conventional acid-precipitation process tightly agglomerated into large particles with apparent sizes of several micrometers, without redispersibility even under an intense sonication treatment.

  6. Photoluminescence and photoconductivity studies on NaBi(WO4)2 single crystals: A promising Cherenkov radiator

    International Nuclear Information System (INIS)

    Tyagi, Mohit; Singh, S.G.; Sen, Shashwati; Singh, A.K.; Gadkari, S.C.

    2012-01-01

    Results of photoluminescence in conjunction with photoconductivity properties of NaBi(WO 4 ) 2 crystal are presented and explained with the help of calculated electronic and optical properties. Crystals were annealed in air/vacuum to change the local environment near (WO 4 ) 2- complex and consequently two emission bands near 470 and 520 nm could be separated for excitation at different energies. The activation energy for thermal quenching of emission was calculated to be 160 meV. The role of excitons and localization of charge carriers is explained on the basis of photoconductivity of these crystals that has been observed only intrinsically in contrast to iso-structurally PbWO 4 . - Highlights: → Results on photoluminescence and photoconductivity of NaBi(WO 4 ) 2 are reported. → These are explained with the help of calculated electronic and optical properties. → Crystals were annealed in air/vacuum to change the local environment near (WO 4 ) 2- . → Emission bands near 470 and 520 nm could be separated for different excitation. → The activation energy for thermal quenching of emission was found to be 160 meV.

  7. 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.

  8. Raman spectroscopy of WO3 nano-wires and thermo-chromism study of VO2 belts produced by ultrasonic spray and laser pyrolysis techniques

    CSIR Research Space (South Africa)

    Mwakikunga, BW

    2008-01-01

    Full Text Available Novel optical and electrical properties of newly synthesized nano-wires of monoclinic WO3 and nano-belts of rutile VO2 have been investigated by Raman spectroscopy and thermochromism studies respectively. Phonon confinement is observed in the WO3...

  9. 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...

  10. 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....

  11. 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.)

  12. Effect of WO3 nanoparticle loading on the microstructural, mechanical and corrosion resistance of Zn matrix/TiO2-WO3 nanocomposite coatings for marine application

    Science.gov (United States)

    Popoola, A. P. I.; Daniyan, A. A.; Umoru, L. E.; Fayomi, O. S. I.

    2017-03-01

    In this study, for marine application purposes, we evaluated the effect of process parameter and particle loading on the microstructure, mechanical reinforcement and corrosion resistance properties of a Zn-TiO2-WO3 nanocomposite produced via electrodeposition. We characterized the morphological properties of the composite coatings with a Scanning Electron Microscope (SEM) equipped with an Energy Dispersive Spectrometer (EDS). We carried out mechanical examination using a Dura Scan hardness tester and a CERT UMT-2 multi-functional tribological tester. We evaluated the corrosion properties by linear polarization in 3.5% NaCl. The results show that the coatings exhibited good stability and the quantitative particle loading greatly enhanced the structural and morphological properties, hardness behavior and corrosion resistance of the coatings. We observed the precipitation of this alloy on steel is greatly influenced by the composite characteristics.

  13. Synthesis, energy transfer and luminescence properties of Ca{sub 2}MgWO{sub 6}:Sm{sup 3+}, Bi{sup 3+} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Renping, E-mail: jxcrp@163.com [College of Mathematics and Physics, Jinggangshan University, Ji’an 343009 (China); Xu, Haidong; Luo, Wenjie [College of Mathematics and Physics, Jinggangshan University, Ji’an 343009 (China); Luo, Zhiyang [College of Mechanical Manufacture and Automation, Jinggangshan University, Ji’an 343009 (China); Guo, Siling [College of Mathematics and Physics, Jinggangshan University, Ji’an 343009 (China); Xiao, Fen [College of Mechanical Manufacture and Automation, Jinggangshan University, Ji’an 343009 (China); Ao, Hui [College of Mathematics and Physics, Jinggangshan University, Ji’an 343009 (China)

    2016-09-15

    Graphical abstract: PL spectra of Ca{sub 2}MgWO{sub 6}:Sm{sup 3+} and Ca{sub 2}MgWO{sub 6}:Sm{sup 3+}, Bi{sup 3+} phosphors with excitation at 407 nm, and the corresponding CIE chromaticity diagram and chromaticity coordinates. - Highlights: • Novel Ca{sub 2}MgWO{sub 6}:Sm{sup 3+}, Bi{sup 3+} phosphor is synthesized by solid-state reaction method in air. • Emission intensity of Ca{sub 2}MgWO{sub 6}:Sm{sup 3+} phosphor is enhanced ∼2 times after co-doped Bi{sup 3+} ion. • Charge compensation and energy transfer may be explained via luminescence properties. • Luminous mechanism is analyzed by energy level diagrams of WO{sub 6}{sup 6−} group, Sm{sup 3+} and Bi{sup 3+} ions. - Abstract: Novel Ca{sub 2}MgWO{sub 6}:Sm{sup 3+}, Bi{sup 3+} phosphor is synthesized by solid-state reaction method in air. Host Ca{sub 2}MgWO{sub 6} with excitation 300 nm emits blue light. Ca{sub 2}MgWO{sub 6}:Bi{sup 3+} phosphor with excitation 300 and 338 nm emits yellow light. Ca{sub 2}MgWO{sub 6}:Sm{sup 3+} phosphor with excitation 300 nm exhibits tunable emission from blue to red light by increasing Sm{sup 3+} doping concentration from 0 to 8 mol%, however, only emits red light with excitation 407 nm. Ca{sub 2}MgWO{sub 6}:Sm{sup 3+}, Bi{sup 3+} phosphor with excitation 300 and 338 nm emits red light. The optimal Sm{sup 3+} doping concentration is ∼5 mol% in Ca{sub 2}MgWO{sub 6}:Sm{sup 3+} phosphor. After Bi{sup 3+} ion is co-doped, luminescence properties of Ca{sub 2}MgWO{sub 6}:Sm{sup 3+} phosphor can be improved obviously because of Bi{sub 2}O{sub 3} as fluxing agent role and energy transfer from Bi{sup 3+} to Sm{sup 3+} ions. The possible luminous mechanism of Ca{sub 2}MgWO{sub 6}:Sm{sup 3+}, Bi{sup 3+} phosphor is analyzed and explained by simplified energy level diagrams of WO{sub 6}{sup 6−} group, Bi{sup 3+} and Sm{sup 3+} ions.

  14. 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.

  15. Subsolidus phase relations in the ZnO-P{sub 2}O{sub 5}-WO{sub 3} system

    Energy Technology Data Exchange (ETDEWEB)

    Yin Shungao [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002 (China); Chen Dagui, E-mail: chendg@fjirsm.ac.c [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002 (China); Liu Weizhen; Wang Yongjing; Lin Zhang; Hong Yangping; Zhan Zhibing [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002 (China); Huang Feng, E-mail: fhuang@fjirsm.ac.c [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002 (China); Liang Jingkui [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002 (China)

    2010-04-30

    The subsolidus phase relations of the ZnO-P{sub 2}O{sub 5}-WO{sub 3} ternary system were investigated by means of X-ray diffraction (XRD). No ternary compound was found in this ternary system, while five binary compounds were obtained and six compatibility triangles were determined. The phase diagram of pseudobinary system Zn{sub 3}(PO{sub 4}){sub 2}-ZnWO{sub 4} was also constructed through XRD and differential thermal analysis (DTA) methods, which forms eutectic system with eutectic temperature about 990 {sup o}C. The corresponding eutectic component is 30 mol% ZnWO{sub 4} and 70 mol% Zn{sub 3}(PO{sub 4}){sub 2}.

  16. 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

  17. 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.

  18. Surfactant Effect on Formation of CaWO4:Eu3+ Crystals with Distinguished Morphologies in Hydrothermal Ambient.

    Science.gov (United States)

    Chen, Ye-Qing; Yang, Guo-Tao; Luo, Jian-Yi; Yang, Ying-Shu; Zeng, Qing-Guang; Jeong, Jung Hyun

    2016-04-01

    Metal tungstates, expressed by the general formula of MWO4, have important properties and applications in photoluminescence, microwave applications, optical fibers, scintillator materials, humidity sensors, magnetic properties, and catalysts. In this paper, we report a successful synthesis of CaWO4:Eul+ crystals with various morphologies in mild hydrothermal conditions with surfacntant including sodium citrate, CTAB, PEG and citrate acid (CA). The formation of the crystals are strongly dependent on the employment of surfactant. The surfactant concentration has been found significant influence in the resulting morphologies due to different properties of each one. Extensive characterization have been performed by using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) in search of the formation mechanism of multi-morphological CaWO4:Eu3+ crystals. The growth mechanism of monodispersed CaWO4:EuS+ crystal are proposed. And the photoluminescence properties were investigated.

  19. Cross-cultural adaptation of the Work Disability Diagnosis Interview (WoDDI) for the Brazilian context.

    Science.gov (United States)

    Mininel, Vivian Aline; Felli, Vanda Elisa Andres; Loisel, Patrick; Marziale, Maria Helena Palucci

    2012-01-01

    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.

  20. 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)

  1. The effect of precursor aging on optical and electrochromic properties of WO3 thin films for making smart windows

    Directory of Open Access Journals (Sweden)

    A Abareshi

    2015-01-01

    Full Text Available This paper proposes a suitable method for increasing effective surface area of electrodeposited WO3 thin films. This is done because effective surface area improves optical and electrochromic properties in smart windows. Therefore, we investigated precursor aging atperoxytungstate precursor (0, 24, 48 and 72 h. Experiments showed by increasing aging time of the precursor solution, larger aggregates were formed. Their morphology, optical and cyclic voltammogram characterization showed that increasing aging time improves optical and electrochromic properties of WO3 thin films in 1M LiClO4-PC electrolyte. The WO3 films with aging time of 72 h exhibited a noticeable EC performance with variation of transmittance up to 72% at 633nm. The result indicated that using two electrochromic materials with complementary properties could improve the function of the device

  2. Enhanced photoelectric conversion efficiency of dye sensitized solar cells via the incorporation of one dimensional luminescent BaWO4:Eu(3+) nanowires.

    Science.gov (United States)

    Wang, Yuping; Qu, Yang; Pan, Kai; Wang, Guofeng; Li, Yadong

    2016-09-25

    One dimensional hierarchical BaWO4:Eu(3+) nanowires have been prepared via a hydrothermal method for the first time. The obtained BaWO4:Eu(3+) nanowires are not only a promising down-conversion luminescence material, but also can be used to improve the efficiency of dye sensitized solar cells, resulting an efficiency of 7.66%, which is a noticeable enhancement of 15% compared to the cell without BaWO4:Eu(3+) nanowires. We suggest that the enhancement of the efficiencies of the TiO2-BaWO4:Eu(3+) composite cells was mainly related to the light scattering of BaWO4:Eu(3+).

  3. 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.

  4. Influence of Morphology and Common Oxidants on the Photocatalytic Property of β-SnWO4 Nanoparticles.

    Science.gov (United States)

    Raj, Arguine Tes; Thangavel, Sakthivel; Rose, Aleena; Jipsa, C V; Jose, Meera; Nallamuthu, Gouthami; Kim, Sang-Jae; Venugopal, Gunasekaran

    2016-03-01

    In this paper, we report a simple, cost effective and surfactant-free method for synthesizing different morphology of β-SnWO4 with irregular, spherical, flake-like and leaf-like structures by using sonochemical method followed by calcination. A well dispersed and highly crystalline β-SnWO4 crystallites with various sizes have been prepared. The samples were characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM), UV-vis spectroscopy, particle size and Zeta potential analyser. The SEM images reveal the successful preparation of an irregular, spherical, flake-like and leaf-like structure of β-SnWO4. The absorption maximum of as-prepared different structures of β-SnWO4 was observed in visible region. The degradation efficiency was found to be increased in leaf-like structures compared to irregular, spherical and flake-like structures of β-SnWO4. Further, an enhanced photocatalytic effect was observed in leaf-like β-SnWO4 nanoparticles while the common oxidants such as peroxomonosulphate (PMS), peroxodisulphate (PDS) and hydrogen peroxide (H2O2) were added. The degradation efficiency of these oxidants was found in the order of PMS > H2O2 > PDS. Generally these oxidants act as electron scavengers. From our experimental results, it is found that maximum efficiency of 93% was achieved when PMS was added. This shows the vital role of common oxidants in photocatalytic characteristics and their future applications in waste-water treatment.

  5. Judd–Ofelt analysis of spectroscopic properties of Eu{sup 3+}:KLu(WO{sub 4}){sub 2} crystal

    Energy Technology Data Exchange (ETDEWEB)

    Loiko, P.A. [Center for Optical Materials and Technologies, Belarusian National Technical University, 65/17 Nezavisimosti Ave., Minsk 220013 (Belarus); Dashkevich, V.I. [B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 68 Nezavisimosti Ave., Minsk 220072 (Belarus); Bagaev, S.N. [Institute of Laser Physics, Siberian Branch of Russian Academy of Sciences, 13/3 Lavrentyev Ave., Novosibirsk 630090 (Russian Federation); Orlovich, V.A. [B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 68 Nezavisimosti Ave., Minsk 220072 (Belarus); Mateos, X.; 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 E-43007 (Spain); Vilejshikova, E.V.; Yasukevich, A.S. [Center for Optical Materials and Technologies, Belarusian National Technical University, 65/17 Nezavisimosti Ave., Minsk 220013 (Belarus); Yumashev, K.V., E-mail: k.yumashev@tut.by [Center for Optical Materials and Technologies, Belarusian National Technical University, 65/17 Nezavisimosti Ave., Minsk 220013 (Belarus); Kuleshov, N.V. [Center for Optical Materials and Technologies, Belarusian National Technical University, 65/17 Nezavisimosti Ave., Minsk 220013 (Belarus); Dunina, E.B.; Kornienko, A.A. [Vitebsk State Technological University, 72 Moskovskaya Ave., Vitebsk 210035 (Belarus); Vatnik, S.M. [Institute of Laser Physics, Siberian Branch of Russian Academy of Sciences, 13/3 Lavrentyev Ave., Novosibirsk 630090 (Russian Federation); Pavlyuk, A.A. [A.V. Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 3 Lavrentyev Ave., Novosibirsk 630090 (Russian Federation)

    2015-12-15

    We report on a comprehensive spectroscopic study of monoclinic Eu:KLu(WO{sub 4}){sub 2} crystal concerning its potential applications in red lasers. Optical absorption and stimulated-emission cross-section spectra are determined for this crystal for the principal light polarizations, E || N{sub p}, N{sub m} and N{sub g}. The maximum σ{sub SE} corresponding to the {sup 5}D{sub 0}→{sup 7}F{sub 4} transition is 1.78×10{sup −20} cm{sup 2} at 703.5 nm (for E || N{sub m}). Spectroscopic properties of Eu:KLu(WO{sub 4}){sub 2} are modeled within the conventional Judd–Ofelt theory, as well as its modification for systems with an anomalously strong configuration interaction (ASCI), yielding absorption oscillator strengths, luminescence branching ratios for {sup 5}D{sub J}→{sup 7}F{sub J'} transitions and radiative lifetimes of the {sup 5}D{sub J} states. Photoluminescent properties of Eu:KLu(WO{sub 4}){sub 2} are studied under UV/visible excitation. Polarized Raman spectra are measured for Eu:KLu(WO{sub 4}){sub 2}. - Highlights: • Top-seeded solution growth of Eu:KLu(WO{sub 4}){sub 2} monoclinic crystal. • Modeling of spectroscopic parameters with modified Judd–Ofelt theory. • Polarization-resolved absorption and stimulated-emission cross-section spectra. • Maximum stimulated-emission cross-section is 1.78×10{sup −20} cm{sup 2} at 703.5 nm. • Polarized Raman spectroscopy of Eu:KLu(WO{sub 4}){sub 2} crystal.

  6. 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

  7. 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

  8. 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

  9. Write-once optical recording using WO2 films prepared by pulsed laser deposition

    International Nuclear Information System (INIS)

    Aoki, Takanori; Matsushita, Tatsuhiko; Suzuki, Akio; Tanabe, Kenji; Okuda, Masahiro

    2006-01-01

    WO 2 films were deposited onto the glass substrates (Corning 7059 with an area of 26 x 38 mm) by the pulsed laser deposition method using an ArF excimer laser. It was found that after annealing at 500 deg. C for 10 min, the film thickness became 1.9 times compared with that (approximately 40 nm) in the as-deposited state. At that time, the difference in the transmittance, ΔT, between the annealed state and the as-deposited state was about 70% at the wavelength of 405 nm. From the XRD and XPS spectra, it was considered that oxygen was absorbed into the tungsten oxide films through the annealing process, accelerating the formation of WO 2 or WO 3 structure which caused the incremental effect in the transmittance and the expansion effect in the film thickness. For the revolution-test of the sample without the protection layer in which the WO 2 films were deposited upon the digital versatile disk (DVD-R) substrate, a write peak power dependence of CNR (at λ = 405 nm, NA = 0.65) of 3T signal (58.5 MHz) was measured at a linear velocity of 5 m/s and a read power of 0.6 mW. The values of CNR of 35 ∼ 40 dB were obtained at the peak power of 5 ∼ 7 mW, and increased largely up to 60 dB at 8 mW, and then reached a maximum of 62 dB at 8.5 mW. After that, the values of the CNR suffered some deterioration at more than 9 mW because of too much expansion of the written dot by which the portion between the dot and neighbor dots became to be invaded. For the dots formed in the writing performance on the DVD-R disk, the expansion effect in direction along the groove or over the neighboring lands was recognized by SEM images. It was found that bits of 0.18 ∼ 0.30 μm size, corresponding to the maximal storage capacity of 25 GB in the 'Blu-ray disk' specification, were made

  10. New self-frequency converted Nd3+:KGd(WO4)2 Raman lasers

    International Nuclear Information System (INIS)

    Ustimenko, N S; Gulin, A V

    2002-01-01

    The spatial orientation of the optical indicatrix axes in a nonlinear neodymium-doped potassium - gadolinium tungstate Nd 3+ :KGd (WO 4 ) 2 crystal is determined more exactly in experiments. Miniature Raman lasers of two types emitting at 1538 nm are built based on this crystal. The laser of the first type has an output energy of 5 - 7 mJ and a pulse repetition rate of up to 1 Hz, while the laser of the second type has an output energy of about 20 mJ and a pulse repetition rate of up to 20 Hz.

  11. New self-frequency converted Nd3+:KGd(WO4)2 Raman lasers

    Science.gov (United States)

    Ustimenko, N. S.; Gulin, A. V.

    2002-03-01

    The spatial orientation of the optical indicatrix axes in a nonlinear neodymium-doped potassium — gadolinium tungstate Nd3+:KGd (WO4)2 crystal is determined more exactly in experiments. Miniature Raman lasers of two types emitting at 1538 nm are built based on this crystal. The laser of the first type has an output energy of 5 — 7 mJ and a pulse repetition rate of up to 1 Hz, while the laser of the second type has an output energy of about 20 mJ and a pulse repetition rate of up to 20 Hz.

  12. PULSED KGd(WO42 RAMAN LASER: TOWARDS EMISSION LINEWIDTH NARROWING

    Directory of Open Access Journals (Sweden)

    V. G. Savitski

    2015-01-01

    Full Text Available The linewidth of a KGd(WO42 pulsed Raman laser is analysed experimentally for different configurations of the Raman and pump resonators: with narrow and broadband pump emission profiles, with and without linewidth narrowing elements in the Raman laser resonator, with and without injection seeding into the Raman cavity. The benefits of a narrow linewidth pump source in combination with linewidth narrowing elements in the Raman laser cavity for the efficient linewidth narrowing of the Raman emission are explained. 20 kW peak-power pulses at 1156 nm with 0,43 cm -1 emission linewidth are demonstrated from an injection seeded KGW Raman laser. 

  13. Comparative analysis of crystal-field parameters for rare-earth ions at monoclinic sites in AB(WO4)2 crystals: I. Tm3+ in KGd(WO4)2 and KLu(WO4)2, and Ho3+ and Er3+ ions in KGd(WO4)2

    International Nuclear Information System (INIS)

    Rudowicz, Czeslaw; Gnutek, Pawel

    2010-01-01

    The crystal-field (CF) parameters determined by various authors for rare-earth ions at monoclinic sites in AB(WO 4 ) 2 crystals are reanalyzed using a methodology incorporating several approaches, namely standardization, multiple-correlated fitting technique and closeness of CFP sets. In Part I recent spectroscopic data for Tm 3+ ions in KGd(WO 4 ) 2 (KGdW) and KLu(WO 4 ) 2 (KLuW), and Ho 3+ and Er 3+ ions in KGdW, which were interpreted using the free-ion (FI) and CF parameter (CFP) sets, are thoroughly revisited. Our reanalysis enables clarification of several doubtful aspects involved in the previous studies. The initial CFPs for fitting, calculated using the simple overlap model (SOM), differ markedly from the fitted CFPs for Tm 3+ ions in KGdW and KLuW. An inspection of the pertinent CFP sets reveals deeper intrinsic differences between the model and fitted CFPs. The model CFPs and the fitted CFPs for RE 3+ ions in both KGdW and KLuW crystals turn out to be non-standard. Importantly, the model and fitted CFP sets for Tm-KLuW belong to disparate regions of the CFP space and thus are intrinsically incompatible, i.e. such sets should not be directly compared. Thus the CFP sets reported in the literature require reconsideration in view of the intrinsic properties of monoclinic CF Hamiltonians previously not taken into account. Standardization of the originally non-standard CFP sets is carried out to ensure direct comparability of the CFP sets in question with other literature data. The correlated alternative CFP sets are calculated for each original set to facilitate future applications of the multiple correlated fitting technique, which enables improving overall reliability of the fitted CFPs. The closeness of the standardized CFP sets is assessed in a quantitative way. Our considerations indicate also the importance of proper definitions of the axis system used in the CFP model calculations and provide arguments for the nominal meaning of the axis systems

  14. The radiation induced colour centers in the NaBi(WO4)2 crystal

    International Nuclear Information System (INIS)

    Shi Hongsheng; Qin Laishun; Chai Wenxiang; Shu Kangying

    2009-01-01

    The radiation induced colour centers in the NaBi(WO 4 ) 2 crystals are investigated. The NBW crystals are irradiated by the Co 60 . The radiation doses are respectively the 10 4 , 10 5 and 10 6 rad and the corresponding dose rate respectively the 40, 2000 and 7000 rad/h. The maximum absorption wavelength of the radiation induced colour centers are identified at 460-470 nm. The mechanism of the formation of the colour centers is discussed. It is assumed that those colour centers are the F colour centers.

  15. Study of temperature dependence of light yield from NaBi(WO4)2 crystals

    International Nuclear Information System (INIS)

    Amosov, C.Yu.; Kalinin, B.N.; Krechetov, Yu.F.; Moiseenko, A.V.; Naumenko, G.A.; Potylitsin, A.P.; Sarytchev, V.P.; Shuvalov, Ye.N.; Vznuzdaev, Ye.A.; Samsonov, V.M.; Solodov, J.P.

    1994-01-01

    The scintillation time structure and the temperature dependence of the light yield from NaBi(WO 4 ) 2 crystals bombarded by 500 MeV electrons have been measured experimentally. These crystals showed a tendency to exhibit scintillator properties when the temperature of the samples was decreased. The light yield increased by more than an order of magnitude with the temperature falling from the room level to that of liquid nitrogen. The scintillation time structure was of a complex pattern, and a slow luminescent component (τ=30 ns) was present in the spectrum. ((orig.))

  16. Wpływ rozszerzenia Unii Europejskiej na stan rynku wołowiny w Polsce

    OpenAIRE

    Bąk-Filipek, Ewa

    2009-01-01

    The aim of this paper was to show the impact of the European Union’s enlargement on the status of beef market in Poland. The analysis was performed on the basis of data on cattle population and production of cattle live weight for years 2004-2008, changes in the retail trade sector in years 1991-2008 and prices for the period of 2004-2008. / Synopsis. Celem opracowania było wskazanie wpływu integracji z Unią Europejską na stan rynku wołowiny w Polsce. Analizę przeprowadzono w oparciu o dane d...

  17. 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

  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. 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.

  1. 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.

  2. Radioactive transitions in NaBi(MoO4)2x(WO4)2(1-x)

    International Nuclear Information System (INIS)

    Ehfendiev, Sh.M.; Darvishov, N.G.; Bobrova, E.Yu.

    1994-01-01

    Photoluminescence in new crystals with scheelite structure and their solid solutions NaBi(MoO 4 ) 2x (WO 4 ) 2(1-x) was studied. The spectra showed two luminescence bands- the blue and green ones in NaBi(WO 4 ) 2 , whereas in NaBi(MoO 4 ) 2 soley a green band was observed. In the solid solutions with an increase in component x the intensity of blue radiation excitation decreased, while the intensity of green radiation excitation did not change. 7 refs., 2 figs

  3. 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

  4. 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%.

  5. Analysis of ferroelectric and magnetic chiral order in MnWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Leo, Naemi; Meier, Dennis; Lottermoser, Thomas; Maringer, Michael; Fiebig, Manfred [HISKP, Universitaet Bonn (Germany); Becker, Petra; Bohaty, Ladislav [Institut fuer Kristallographie, Universitaet Koeln (Germany)

    2009-07-01

    Spin spiral systems form a particularly interesting subgroup of magnetoelectric multiferroics since violation of inversion symmetry by long-wavelength magnetic order is responsible for the spontaneous electric polarisation. Such intrinsic coupling of magnetism and ferroelectricity is not only promising with respect to future spintronic applications. It also enables fascinating physical effects like the magnetic-field-induced polarisation flop in TbMnO{sub 3} or MnWO{sub 4}. In our studies we focus on MnWO{sub 4}, which is a remarkable example of a spin-spiral multiferroic because a single transition-metal ion is responsible for the coexistence of magnetic and electric order. We present a spectral analysis of its multiferroic phase by means of optical second harmonic generation (SHG). With respect to symmetry dependent selection rules we distinguish between crystallographic, antiferromagnetic (AFM) and ferroelectric (FE) SHG contributions of different multipole order. Characteristic temperature dependencies of the associated FE and AFM order parameters further support the attribution.

  6. Topological magnetoelectric memory effect in the spin-spiral multiferroic MnWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Meier, Dennis; Leo, Naemi; Lottermoser, Thomas; Fiebig, Manfred [HISKP, Universitaet Bonn (Germany); Becker, Petra; Bohaty, Ladislav [Institut fuer Kristallographie, Universitaet zu Koeln (Germany)

    2010-07-01

    Within the field of multiferroics, i.e. compounds with coexisting magnetic and electric order, so-called spin-spiral ferroelectrics attract tremendous attention. In these systems magnetic long-range order violates the inversion symmetry and induces a spontaneous electric polarization. Magnetic and electric domains are thus rigidly coupled so that ''giant'' magnetoelectric effects are obtained. However, up to now nearly nothing is know about the topology of the domain state in these systems. We report spatially-resolved measurements of the multiferroic domain topology in MnWO{sub 4}. For the first time, the full three-dimensional domain structure in a spin-spiral system is imaged. Our study reveals that the multiferroic domains in magnetically-induced ferroelectrics unify features that are associated to a magnetic domain state and others that point unambiguously to ferroelectric domains. Hence, a description in terms of ferroelectric or antiferromagnetic domains is incomplete and no longer appropriate. The novel concept of ''multiferroic hybrid domains'' is introduced. Annealing cycles reveal a topological memory effect: Due to phase coexistence at one phase boundary limiting the multiferroic state in MnWO{sub 4}, the entire multiferroic multidomain state can be reconstructed subsequent to quenching it.

  7. 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)>>>>

  8. Interfacing Photosynthetic Membrane Protein with Mesoporous WO3 Photoelectrode for Solar Water Oxidation.

    Science.gov (United States)

    Pang, Hong; Zhao, Guixia; Liu, Guigao; Zhang, Huabin; Hai, Xiao; Wang, Shengyao; Song, Hui; Ye, Jinhua

    2018-04-10

    Photosynthetic biocatalysts are emerging as a new class of materials, with their sophisticated and intricate structure, which promise improved remarkable quantum efficiency compared to conventional inorganic materials in artificial photosynthesis. To break the limitation of efficiency, the construction of bioconjugated photo-electrochemical conversion devices has garnered substantial interest and stood at the frontier of the multidisciplinary research between biology and chemistry. Herein, a biohybrid photoanode of a photosynthetic membrane protein (Photosystem II (PS II)), extracted from fresh spinach entrapped on mesoporous WO 3 film, is fabricated on fluorine-doped tin oxide. The PS II membrane proteins are observed to communicate with the WO 3 electrode in the absence of any soluble redox mediators and sacrificial reagents under the visible light of the solar spectrum, even to 700 nm. The biohybrid electrode undergoes electron transfer and generates a significantly enhanced photocurrent compared to previously reported PS II-based photoanodes with carbon nanostructures or other semiconductor substrates for solar water oxidation. The maximum incident photon-to-current conversion efficiency reaches 15.24% at 400 nm in the visible light region. This work provides some insights and possibilities into the efficient assembly of a future solar energy conversion system based on visible-light-responsive semiconductors and photosynthetic proteins. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. 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.

  10. 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

    2015-01-01

    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. PMID:26359212

  11. 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.

  12. Photoluminescence and excited states dynamics in PbWO4:Pr3+ crystals

    CERN Document Server

    Auffray, E; Shalapska, T; Zazubovich, S

    2014-01-01

    Luminescence and photo-thermally stimulated defects creation processes are studied for a Pr3+-doped PbWO4 crystal at 4.2-400 K under excitation in the band-to-band, exciton, and charge-transfer transitions regions, as well as in the Pr3+-related absorption bands. Emission spectra of Pr3+ centers depend on the excitation energy, indicating the presence of Pr3+ centers of two types. The origin of these centers is discussed. The 2.03-2.06 eV emission, arising from the D-1(2) -> H-3(4) transitions of Pr3+ ions, is found to be effectively excited in a broad intense absorption band peaking at 4.2 K at 3.92 eV. By analogy with some other Pe(3+)-doped compounds, this band is suggested to arise from an electron transfer from an impurity Pr3+ ion to the crystal lattice W6+ or Pb2+ ions. The dynamics of the Pr3+-related excited states is clarified. In the PbWO4:Pr crystal studied, the concentration of single oxygen and lead vacancies as traps for electrons and holes is found to be negligible.

  13. 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.

  14. Magnetic behavior of Ca{sub 2}NiWO{sub 6} double perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, C.A. [Area de Quimica General e Inorganica ' Dr. G.F.Puelles' , Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis (Argentina); Curiale, J. [Centro Atomico Bariloche and Instituto Balseiro (UNCuyo), CNEA, Av. Bustillo 9500 (R8402AGP) S. C. de Bariloche, RN (Argentina); Viola, M. del C. [Area de Quimica General e Inorganica ' Dr. G.F.Puelles' , Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis (Argentina); Pedregosa, J.C. [Area de Quimica General e Inorganica ' Dr. G.F.Puelles' , Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis (Argentina)]. E-mail: jpedreg@unsl.edu.ar; Sanchez, R.D. [Centro Atomico Bariloche and Instituto Balseiro (UNCuyo), CNEA, Av. Bustillo 9500 (R8402AGP) S. C. de Bariloche, RN (Argentina)]. E-mail: rodo@cab.cnea.gov.ar

    2007-09-01

    Polycrystalline Ca{sub 2}NiWO{sub 6} double perovskite has been prepared by solid-state reaction at 1150 C. The crystal structure of this material has been confirmed by X-ray powder diffraction (XRD). At room temperature, the crystal structure is monoclinic, space group P2{sub 1}/n, with a=5.4061(2) A, b=5.5389(2) A, c=7.6895(3) A, {beta}=90.232(2){sup o}. Magnetic susceptibility and electron spin resonance experiments on Ca{sub 2}NiWO{sub 6} show at high temperature a Curie-Weiss behavior with a {theta}=-75 K. From the Curie-Weiss behavior, the effective magnetic moment is 2.85{mu} {sub B}, which is in agreement with the presence of Ni{sup 2+} in the system. At low temperatures, below 52.5(0.2) K, the magnetic susceptibility shows antiferromagnetic behavior. From the experimental data and the mean field theory of antiferromagnetism we estimated the Ni interactions among the nearest Ni neighbors and the second nearest Ni neighbors.

  15. Formulation and evaluation of antisebum secretion effects of sea buckthorn w/o emulsion

    Directory of Open Access Journals (Sweden)

    Naveed Akhtar

    2010-01-01

    Full Text Available Purpose : This study was designed to formulate and evaluate the anti-sebum secretion effects of a topical skin-care cream (w/o emulsion of sea buckthorn versus its vehicle (Base as control. Materials and Methods : Concentrated sea buckthorn (H.rhamnoides fruit extract was entrapped in the inner aqueous phase of w/o emulsion. Base containing no extract and a Formulation containing 1% concentrated extract of H.rhamnoides was formulated. Lemon oil was incorporated to the odor. Both the Base and the Formulation were stored at different storage conditions for a period of 4 weeks to predict their stability. Different stability parameters i.e.; physical stability, centrifugation, and pH were monitored at different time intervals. Both the Base and the Formulation were applied to the cheeks of 10 healthy human volunteers (n=10 for a period of 8 weeks. Result : The expected organoleptic stability of creams was achieved from 4 weeks in-vitro study period. Odor disappeared with the passage of time due to volatilization of lemon oil. The pH of the Formulation showed significant ( P = 0.0002 decline due to high concentration of organic acids present in sea buckthorn. Similarly the Formulation showed statistically significant ( P < 0.05 effects on skin sebum secretion. Conclusion : The in vitro results showed a good stability over 4 weeks of observation period of both the Base and Formulation and the Formulation has anti sebum secretion effects over 8 weeks of observation period.

  16. 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.

  17. Hadron calorimeter performance with a PbWO4 EM compartment

    Energy Technology Data Exchange (ETDEWEB)

    Green, D.

    1996-01-01

    The CMS detector[1] at the LHC has chosen PbWO4 in order to achieve the superior photon energy resolution which is crucial in searching for the 2 photon decay of low mass Higgs bosons. The hadronic compartment is thought to be Cu absorber, since one is immersed in a 4 T magnetic field, read out by scintillator tiles coupled to wavelength shifter (WLS) fibers. The combined performance of this calorimeter is of interest in the study of jets and missing transverse energy (neutrino, SUSY signatures). For this reason, a test was made of the electromagnetic (EM) compartment combined with a reasonable approximation to the baseline HCAL ``barrel`` calorimeter. Data was taken in the H4 CERN beamline. The EM compartment was a 7 {times} 7 square array of PbWO4 crystals, which for the purposes of this study are considered as a single readout in depth (or ``compartment``) [2]. The HCAL module consisted of large scintillator plates with 24 individual longitudinal readout channels. The EM compartment was followed by 10 Cu plates each 3 cm thick, followed by 9 Cu plates each 6 cm thick. This set of absorber plates represented the HCAL compartments inside the coil. The coil itself [1] was approximated as Al and Fe plates, of a total thickness of about 1.4 absorption lengths. The coil mockup was sampled and then followed by 4 plates of 8 cm thick Cu, each with an individual readout which represented a test of the ``Tailcatcher`` concept.

  18. 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

  19. Construction and Nanoscale Detection of Interfacial Charge Transfer of Elegant Z-Scheme WO3/Au/In2S3 Nanowire Arrays.

    Science.gov (United States)

    Li, Haijin; Gao, Yuying; Zhou, Yong; Fan, Fengtao; Han, Qiutong; Xu, Qinfeng; Wang, Xiaoyong; Xiao, Min; Li, Can; Zou, Zhigang

    2016-09-14

    Elegant Z-scheme WO3/Au/In2S3 nanowire arrays were precisely constructed through a facile step-by-step route. Surface potential change on pristine or In2S3-Au coated WO3 single nanowire under dark and illumination detected through a Kelvin probe force microscopy (KPFM) technique indicates that the vectorial holes transfer of In2S3 → Au → WO3 should occur upon the excitation of both WO3 and In2S3. In such charge transfer processes, the embedded Au nanoparticles in the heterojunction systems act as a charge mediator for electrons in the conduction band of WO3 and holes in the valence band of In2S3. The strong charge carrier separation ability of this structure will finally enhance the oxidation ability of WO3 with high concertation of photogenerated holes and, further, leave the free electrons in the In2S3 with long surviving time. Therefore, the unique Z-scheme WO3/Au/In2S3 heterostructure shows great visible-light activity toward photocatalytic reduction of CO2 in the presence of water vapor into renewable hydrocarbon fuel (methane: CH4).

  20. Photocatalytic removal of gaseous nitrogen oxides using WO3/TiO2 particles under visible light irradiation: Effect of surface modification.

    Science.gov (United States)

    Mendoza, Joseph Albert; Lee, Dong Hoon; Kang, Joo-Hyon

    2017-09-01

    Photocatalytic nanoparticles have been receiving considerable attention for their potential use in many environmental management applications, including urban air quality control. This paper investigates the performance of surface modified WO 3 /TiO 2 composite particles in removing gaseous nitrogen oxides (NO x ) under visible light irradiation. The WO 3 /TiO 2 composite particles were synthesized using a modified wet chemical method with different concentrations of NaOH solution used as a surface modification agent for the host TiO 2 particles. The NO x removal efficiency of the WO 3 /TiO 2 particles was evaluated using a lab-scale continuous gas flow photo-reactor with a gas contact time of 1 min. Results showed that surface modification using NaOH can enhance the photocatalytic activity of the WO 3 /TiO 2 particles. The NO x removal efficiency of the surface modified WO 3 /TiO 2 was greater than 90%, while that of WO 3 /TiO 2 particles prepared by the conventional wet chemical method was ∼75%. The enhanced removal efficiency might be attributed to the formation of oxygen vacancies on the TiO 2 surface, providing sites for WO 3 particles to effectively bind with TiO 2 . However, excess amount of NaOH >3 M deteriorated the photocatalytic performance due to the increased agglomeration of the host TiO 2 particles. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Facile formation of Ag2WO4/AgX (X = Cl, Br, I) hybrid nanorods with enhanced visible-light-driven photoelectrochemical properties

    International Nuclear Information System (INIS)

    Li, Jingjing; Yu, Caiyun; Zheng, Changcheng; Etogo, Atangana; Xie, Yunlong; Zhong, Yijun; Hu, Yong

    2015-01-01

    Highlights: • Ag 2 WO 4 /AgX hybrid nanorods were prepared by a facile in-situ anion exchange reaction. • Ag 2 WO 4 nanorods and different X − ions were reacted in water at room temperature. • The hybrids possess significantly enhanced photoelectrochemical properties. • Ag 2 WO 4 /AgBr hybrids exhibit the highest photocatalytic activity among three samples. • The active species tests were also investigated to confirm photocatalytic mechanism. - Abstract: In this work, we demonstrated a general strategy for the preparation of a series of uniform Ag 2 WO 4 /AgX (X = Cl, Br, I) hybrid nanorods by a facile in-situ anion exchange reaction occurring at room temperature between pregrown Ag 2 WO 4 nanorods and different X − ions in water. Compared with Ag 2 WO 4 nanorods, further investigation has revealed that the as-prepared hybrid nanorods possess significantly enhanced photocurrent response and photocatalytic activity in degrading methyl orange (MO) under visible-light irradiation. In particular, the Ag 2 WO 4 /AgBr hybrid nanorods exhibit the highest photocatalytic activity among the three kinds of samples. The active species tests indicate that superoxide anion radicals and photogenerated holes are responsible for the enhanced photocatalytic performance

  2. CeO2/Bi2WO6Heterostructured Microsphere with Excellent Visible-light-driven Photocatalytic Performance for Degradation of Tetracycline Hydrochloride.

    Science.gov (United States)

    Zhang, Fengjun; Zou, Shuang; Wang, Tianye; Shi, Yuxi; Liu, Peng

    2017-10-01

    CeO 2 /Bi 2 WO 6 heterostructured microsphere with excellent and stable photocatalytic activity for degradation tetracyclines was successfully synthesized via a facile solvothermal route. The photocatalytic experiments indicated that CeO 2 /Bi 2 WO 6 heterostructured microspheres exhibited enhanced photocatalytic activity compared to pure Bi 2 WO 6 in both the degradation of tetracycline hydrochloride (TCH) and rhodamine B (RhB) under visible-light irradiation. The 1CeO 2 /2Bi 2 WO 6 exhibited the best photocatalytic activity for degradation of TCH, reaching 91% after 60 min reaction. The results suggested that the particular morphological conformation of the microspheres resulted in smaller size and more uniform morphology so as to increase the specific surface area. Meanwhile, the heterojunction was formed by coupling CeO 2 and Bi 2 WO 6 in the as-prepared microspheres, so that the separation efficiency of photogenerated electrons and holes was dramatically improved and the lifetimes of charge carriers were prolonged. Hence, introduction of CeO 2 could significantly enhance the photocatalytic activity of CeO 2 /Bi 2 WO 6 heterostructured microspheres and facilitate the degradation of TCH. This work provided not only a principle method to synthesize CeO 2 /Bi 2 WO 6 with the excellent photocatalytic performance for actual produce, but also a excellent property of the photocatalyst for potential application in photocatalytic treatment of tetracyclines wastewater from pharmaceutical factory. © 2017 The American Society of Photobiology.

  3. Fabrication of the heterostructured CsTaWO6/Au/g-C3N4 hybrid photocatalyst with enhanced performance of photocatalytic hydrogen production from water

    Science.gov (United States)

    Lang, Junyu; Liu, Mengqing; Su, Yiguo; Yan, Lijuan; Wang, Xiaojing

    2015-12-01

    In this work, a novel CsTaWO6/Au/g-C3N4 hybrid photocatalyst is successfully fabricated. The photocatalytic performance of the heterostructured CsTaWO6/Au/g-C3N4 composite was investigated. Au nanoparticles were photo-deposited as the interlayer between g-C3N4 and the surface of CsTaWO6, which can facilitate the photoinduced electrons migration as an electron-conduction bridge as well as increase visible-light absorption via the surface plasmon resonance. This heterostructured interface bridging by Au particles may significantly retard the recombination of electron-holes, which is beneficial to promote the photocatalytic activity under visible-light irradiation. It is found the CsTaWO6/Au/g-C3N4 sample showed excellent photocatalytic activity of water splitting, even higher than the sum of g-C3N4 and Au/CsTaWO6 samples, or the sum of CsTaWO6 and Au/g-C3N4 samples. It indicates that the heterostructured combination of g-C3N4 and CsTaWO6 bridging by Au particles provided the synergistic photocatalytic activity driving by solar light through an efficient electron transfer process.

  4. Controllable synthesis of Bi2WO6 nanoplate self-assembled hierarchical erythrocyte microspheres via a one-pot hydrothermal reaction with enhanced visible light photocatalytic activity

    Science.gov (United States)

    Yang, Zhenya; Huang, Lin; Xie, Yanyu; Lin, Zheguan; Fan, Yunyan; Liu, Dan; Chen, Lu; Zhang, Zizhong; Wang, Xuxu

    2017-05-01

    This work provides a simple approach of the F--assisted one-pot hydrothermal reaction to successfully synthesize Bi2WO6 hierarchical erythrocyte microspheres. The importance role of F- was systematically investigated by comparing different type of halogen ions, hydrothermal temperature and time. The possible growth mechanism of Bi2WO6 hierarchical structures was proposed. The hierarchical erythrocytes were formed through the well-ordered and oriented self-assembly of thin Bi2WO6 nanoplate primary subunits. F- ions were absorbed on Bi2WO6 nanoplate surface to suppress the nanoplate stack but to induce a self-assembly through the edge interaction of Bi2WO6 nanoplates into erythrocyte-like hierarchical microspheres superstructures. This erythrocyte structure narrowed the band gap energy and enhanced the visible-light photocatalytic activity of Bi2WO6. Moreover, superoxide radical anions and h+ were revealed as the main active species responding for the RhB degradation on Bi2WO6 under visible light irradiation.

  5. 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.

  6. 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.

  7. Surface Structure and Photocatalytic Properties of Bi2WO6 Nanolatelets Modified by Molybdena Islands from Chemical Vapor Deposition

    NARCIS (Netherlands)

    Dittmer, A.; Menze, J.; Mei, Bastian Timo; Strunk, J.; Luftman, H.S.; Gutkowski, R.; Wachs, I.E.; Schuhmann, W.; Muhler, M.

    2016-01-01

    We report on a novel route of preparing molybdena-modified bismuth tungstates and their successful application in the photocatalytic oxygen evolution reaction and the oxidation of glycerol. Hierarchically assembled monocrystalline Bi2WO6 nanoplatelets with a specific surface area of 10 m2/g were

  8. The ternary system Na{sub 2}O-ZnO-WO{sub 3}: Compounds and phase relationships

    Energy Technology Data Exchange (ETDEWEB)

    Yan Fengbo; Chen Dagui; Li Wei; Lin Zhang; Zhao Zhenguo; Xue Liping [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Huang Feng [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)], E-mail: fhuang@fjirsm.ac.cn; Liang Jingkui [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100080 (China); International Centre for Materials Physics, Chinese Academia Sinica, Shenyang 110016 (China)], E-mail: jkliang@aphy.iphy.ac.cn

    2008-06-30

    The subsolidus phase relationships of ternary system Na{sub 2}O-ZnO-WO{sub 3} have been investigated by X-ray diffraction (XRD) and differential thermal analyzer (DTA). All the samples were synthesized in the temperature range from 530 to 850 deg. C in air. There are one ternary compound and five binary compounds in the Na{sub 2}O-ZnO-WO{sub 3} system, which can be divided into eight three-phase regions. The crystal structure of the ternary compound Na{sub 3.6}Zn{sub 1.2}(WO{sub 4}){sub 3} is determined by single-crystal structure analysis method. It belongs to triclinic system with space group P1-bar and lattice constants a = 7.237 (5) A, b = 9.172 (6) A, c = 9.339 (6) A and {alpha} = 94.920 (4){sup o}, {beta} = 105.772 (9){sup o}, {gamma} = 103.531 (8){sup o}, Z = 2. DTA analyses indicate that the compound Na{sub 2}WO{sub 4} is not suitable to be the flux for ZnO crystal growth below 1250 deg. C, since no liquidus was observed in the system before 1250 deg. C.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. Fabrication of optical planar waveguides in KY(WO4)2 by He-ion implantation

    NARCIS (Netherlands)

    Borca, C.N.; Zäh, F.; Schnider, C.; Salathé, R.P.; Pollnau, Markus; Moretti, P.

    In this paper, planar waveguides produced by He-ion implantation have been demonstrated in undoped and Yb-doped KY(WO/sub 4/)/sub 2/ crystals. The effective refractive indices of guided modes in surface planar waveguides were measured by dark m-line spectroscopy and the refractive index profiles

  14. Photocatalytic ability of Bi6Ti3WO18 nanoparticles with a mix-layered Aurivillius structure

    Science.gov (United States)

    Mi, Longqing; Feng, Yongyi; Cao, Lei; Xue, Mingqiang; Qin, Chuanxiang; Huang, Yanlin; Qin, Lin; Seo, Hyo Jin

    2018-01-01

    Aurivillius phase layered perovskites Bi6Ti3WO18 was prepared by the sol-gel citrate-complexation synthesis. The sample developed into the plate-like nanoparticles with the exposed (001) facets. The phase formation and structure have been verified via X-ray polycrystalline powder diffraction (XRD) Rietveld refinements. The nanoparticles were investigated via the measurements such as FE-SEM, TEM, EDS, and the surface analyses. UV-Vis absorption data revealed that the Aurivillius compound has a direct band characteristic with the band energy of 2.214 eV. The band structure of Bi6Ti3WO18 nanoparticles was discussed on the base of the experiments and theoretical calculation. Bi3+-containing Aurivillius Bi6Ti3WO18 shows efficient photocatalytic degradation for rhodamine B dye (RhB) with the visible light irradiation ( λ > 420 nm). Dynamic characteristic of the light-created excitons was measured by the luminescence and decay lifetime. The multivalent properties of W and Ti ions in the Aurivillius-like lattices of Bi6Ti3WO18 photocatalyst were discussed.

  15. 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

  16. 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

  17. 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.

  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. 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.

  20. Resolution Properties of a Calcium Tungstate (CaWO4) Screen Coupled to a CMOS Imaging Detector

    Science.gov (United States)

    Koukou, Vaia; Martini, Niki; Valais, Ioannis; Bakas, Athanasios; Kalyvas, Nektarios; Lavdas, Eleftherios; Fountos, George; Kandarakis, Ioannis; Michail, Christos

    2017-11-01

    The aim of the current work was to assess the resolution properties of a calcium tungstate (CaWO4) screen (screen coating thickness: 50.09 mg/cm2, actual thickness: 167.2 μm) coupled to a high resolution complementary metal oxide semiconductor (CMOS) digital imaging sensor. A 2.7x3.6 cm2 CaWO4 sample was extracted from an Agfa Curix universal screen and was coupled directly with the active area of the active pixel sensor (APS) CMOS sensor. Experiments were performed following the new IEC 62220-1-1:2015 International Standard, using an RQA-5 beam quality. Resolution was assessed in terms of the Modulation Transfer Function (MTF), using the slanted-edge method. The CaWO4/CMOS detector configuration was found with linear response, in the exposure range under investigation. The final MTF was obtained through averaging the oversampled edge spread function (ESF), using a custom-made software developed by our team, according to the IEC 62220-1-1:2015. Considering the renewed interest in calcium tungstate for various applications, along with the resolution results of this work, CaWO4 could be also considered for use in X-ray imaging devices such as charged-coupled devices (CCD) and CMOS.

  1. 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

  2. Growth, structural, electrical and optical properties of the thermally evaporated tungsten trioxide (WO{sub 3}) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Patel, K.J. [Applied Physics Department, Faculty of Technology and Engineering, M.S. University of Baroda, Vadodara 390001, Gujarat (India); Panchal, C.J. [Applied Physics Department, Faculty of Technology and Engineering, M.S. University of Baroda, Vadodara 390001, Gujarat (India)], E-mail: cjpanchal_msu@yahoo.com; Kheraj, V.A.; Desai, M.S. [Applied Physics Department, Faculty of Technology and Engineering, M.S. University of Baroda, Vadodara 390001, Gujarat (India)

    2009-03-15

    Tungsten trioxide (WO{sub 3}) thin films are of great interest due to their enormous and promising applications in various opto-electronic thin-film devices. We have investigated the structural, electrical, and optical properties of the WO{sub 3} thin films grown by thermal evaporation of WO{sub 3} powder and their dependence on growth condition. The WO{sub 3} thin films were grown on glass substrates at different substrate temperature varying from room temperature to 510 deg. C. The structural characterization and surface morphology were carried out using X-ray diffraction and atomic force microscopy, respectively. The amorphous films were obtained at substrate temperatures below 450 deg. C whereas films grown above 450 deg. C were crystalline. The surface roughness and the grain size of the films increase on increasing the substrate temperature. The electrical characterization has been carried out using four-point-probe methods. The resistivity of the films decreases significantly while the carrier concentration and mobility increase with the substrate temperature. The transparency and optical energy band-gap, E{sub g}, of the films are found to decrease monotonically as the substrate temperature increases.

  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 and their hy...

  4. Structural and photoluminescence behavior of thermally stable Eu3+activated CaWO4 nanophosphors via Li+ incorporation

    Science.gov (United States)

    Ramakrishna, P. V.; Lakshmana Rao, T.; Singh, Arvind; Benarji, B.; Dash, S.

    2017-12-01

    We have studied the structural and photo physical analogue of Eu3+ activated CaWO4 nanophosphors via Lithium (Li+ = 2, 5 7 and 10 at.%) ion incorporation. As-prepared (APS) samples were annealed at 900 °C to eliminate unwanted organic moieties present in the sample and to improve crystallinity. The samples are characterized employing X-ray diffraction (XRD), Fourier transform IR spectroscopy (FTIR), UV-VIS spectroscopy, photoluminescence studies and lifetime decay studies. FTIR features an absorption band at ∼832 cm-1, which correspond to its antisymmetric vibrations into Osbnd Wsbnd O band in the WO42- tetrahedron. CaWO4 having the scheelite type structure with C4h point group and I41/a space group. The surface morphology of the samples are studied with Scanning Electron Microscopy (SEM). Lithium Co-doped CaWO4:Eu3+ nanoparticles show red luminescence because of strong host contribution and different energy transfer rates from host to Eu3+ ions under 266 nm excitations. Lithium ion enhances the crystallinity and radiative transition rate thus results in higher emissive property. Calculated CIE co-ordinates of these Li+ doped 900 °C annealed samples under 266 nm excitation is x = 0.65 & y = 0.34, which are closer to the standard of NTSC (x = 0.67 & y = 0.33). This material may be potential candidates for white light emitting diodes.

  5. Scitillation characteristics of PbWO.sub.4./sub. single crystals doped with Th, Zr, Ce, Sb and Mn ions

    Czech Academy of Sciences Publication Activity Database

    Kobayashi, M.; Usuki, Y.; Ishii, M.; Senguttuvan, N.; Tanji, K.; Chiba, M.; Hara, K.; Nikl, Martin; Boháček, Pavel; Boccaro, S.

    2001-01-01

    Roč. 465, - (2001), s. 428-439 ISSN 0168-9002 R&D Projects: GA MŠk ME 159 Institutional research plan: CEZ:AV0Z1010914 Keywords : PbWO 4 * tetravalent-ion (Th 4 ) doping Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.026, year: 2001

  6. Photo- and thermally stimulated luminescence of non-stoichiometric undoped PbWO.sub.4./sub. crystals

    Czech Academy of Sciences Publication Activity Database

    Zazubovich, S.; Nikl, Martin

    2010-01-01

    Roč. 247, č. 2 (2010), s. 385-392 ISSN 0370-1972 Institutional research plan: CEZ:AV0Z10100521 Keywords : PbWO 4 * single crystal * nonstoichiometric * luminescence * defects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.344, year: 2010

  7. Synthesis and characterization of WO 3 nanoparticles prepared by the precipitation method: Evaluation of photocatalytic activity under vis-irradiation

    Science.gov (United States)

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

    2010-01-01

    WO 3 nanoparticles were synthesized by the precipitation method varying the time employed in the formation of their precursor in aqueous media and the calcination temperature. The WO 3 crystallization process and morphology of the synthesized samples were followed by the XRD, TEM and SEM techniques. The effects of the calcination temperature on the surface area and optical properties of the WO 3 nanoparticles were also investigated. Nanoparticles with morphologies such as square and rectangular plates and ovoid forms were observed for the different experimental conditions. WO 3 nanoparticles with different morphologies were tested for the photocatalytic degradation of organic dyes. In general, the photocatalysts showed a capacity to bleach the dye solution in the following sequence: indigo carmine (IC) > rhodamine B (rhB) > congo red (CR). The extent of mineralization was determined by means of total organic carbon (TOC) measurements, which showed a satisfactory TOC reduction (93%, within 75 h) only for IC. This value was even better than the one concerning the P-25 Degussa reference.

  8. Improvement of optical properties and radiation hardness of NaBi(WO4)2 Cherenkov crystals

    International Nuclear Information System (INIS)

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

    2002-01-01

    On the basis of the data on melt evaporation while growing NaBi(WO 4 ) 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 3 has been established to increase optical transmission and radiation hardness and lack of Bi 2 O 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 4 ) 2 :Sc crystals compared with undoped NaBi(WO 4 ) 2 of approximately 15%

  9. 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%.

  10. 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.

  11. 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

  12. 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

  13. Anomalous ionic conductivity of Sc sub 2 (WO sub 4) sub 3 mediated by structural changes at high pressures and temperatures

    CERN Document Server

    Secco, R A; Imanaka, N; Adachi, G

    2002-01-01

    The ionic conductivity of Sc sub 2 (WO sub 4) sub 3 at 400 deg. C shows a normal decrease with increase in pressure up to 2.9 GPa but then increases anomalously at pressures up to 4.3 GPa. Synchrotron in situ x-ray diffraction results show that Sc sub 2 (WO sub 4) sub 3 undergoes pressure-induced amorphization at pressures coincident with the reversal in conductivity behaviour. The loss of crystal structure at high pressure may be associated with the property of negative thermal expansion in Sc sub 2 (WO sub 4) sub 3.

  14. Novel Bi2WO6-coupled Fe3O4Magnetic Photocatalysts: Preparation, Characterization and Photodegradation of Tetracycline Hydrochloride.

    Science.gov (United States)

    Wang, Tianye; Zhong, Shuang; Zou, Shuang; Jiang, Fuhuan; Feng, Limin; Su, Xiaosi

    2017-07-01

    Novel Bi 2 WO 6 -coupled Fe 3 O 4 magnetic photocatalysts with excellent and stable photocatalytic activity for degrading tetracycline hydrochloride and RhB were successfully synthesized via a facile solvothermal route. Through the characterization of the as-prepared magnetic photocatalysts by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectra, it was found that the as-prepared magnetic photocatalysts were synthesized by the coupling of Bi 2 WO 6 and Fe 3 O 4 , and introduction of appropriated Fe 3 O 4 can improve nanospheres morphology and visible-light response. Among them, BFe2 (0.16% Fe 3 O 4 ) exhibited the best photocatalytic activity for degradation of tetracycline hydrochloride (TCH), reaching 81.53% after 90 min. Meanwhile, the as-prepared magnetic photocatalysts showed great separation and recycle property. Moreover, the results of electrochemical impedance spectroscopy demonstrated that the well conductivity of Fe 3 O 4 can promote photogenerated charge carriers transfer and inhibit recombination of electron-hole pairs, so that Bi 2 WO 6 /Fe 3 O 4 exhibited enhanced photocatalytic activity on degradation of TCH and RhB. Hence, this work provides a principle method to synthesize Bi 2 WO 6 /Fe 3 O 4 with excellent photocatalytic performance for actual application, in addition, it showed that introduction of Fe 3 O 4 not only can provide magnetism, but also can enhance photocatalytic activity of Bi 2 WO 6 /Fe 3 O 4 magnetic photocatalysts. © 2017 The American Society of Photobiology.

  15. 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.

  16. 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

  17. Neutron and X-ray difraction studies on the Bi2O3-WO3 system

    International Nuclear Information System (INIS)

    Zelada Silva, G.

    1984-01-01

    Different crystallographic phases of the (1-X) (Bi2O3) x (WO3) system were studied, with X in the range 0.12 0 C and then quenched on liquid nitrogen to freeze the high temperature structure. Another set of identical sampoes were slowly cooled to room temperature in order to abtain the equilibrium phase at this temperatutre. The X-ray data show good agreement whit published resiults, with the exception of a new phase appearting at room temperature instead of the σ phase, showing that the last is stable only at high temperatures. Neiutron diffraction refinements lead to an structural model with catins situated at ideal distributed between two different crystallographic sites: a) oxygen atoms shifted from the ideal site toward the direction, and b) interstitial oxygen atoms apart from the (1/2 1/2 1/2) intertice following the axis. (Author)

  18. 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)

  19. 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.)

  20. 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.

  1. 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)

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Temperature dependence of structural parameters in the perovskite Na0.74WO3

    International Nuclear Information System (INIS)

    Darlington, C.N.W.; Hriljac, J.A.; Knight, K.S.

    2005-01-01

    Na x WO 3 undergoes three phase transitions involving tilting of the oxygen octahedra about left angle 100 right angle pseudocubic directions. We have measured the temperature dependence of the lattice parameters between 200 and 750 K - a temperature range that spans the three transitions - and determined the evolution of the structure within each phase as temperature changes. The experiments were performed on the high-resolution powder diffractometer HRPD, Rutherford Appleton Laboratory, UK, using time-of-flight neutron diffraction. The critical exponent that describes the temperature dependence of the total tilt angle has been evaluated. An unexpected change in the thermal expansion coefficient in the cubic phase is not understood: an argument based on Landau's theory of phase transitions is used to demonstrate that the change is not the result of co-existence of two phases. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Mapping residual stresses in PbWO$_{4}$ crystals using photo-elastic analysis

    CERN Document Server

    Lebeau, Michel; Majni, G; Paone, N; Pietroni, P; Rinaldi, D

    2005-01-01

    Large scintillating crystals are affected by internal stresses induced by the crystal growth temperature gradient remanence. Cutting boules (ingots) into finished crystal shapes allows for a partial tension relaxation but residual stresses remain the main cause of breaking. Quality control of residual stresses is essential in the application of Scintillating Crystals to high-energy physics calorimeters (e.g. CMS ECAL at CERN LHC). In this context the industrial process optimisation towards stress reduction is mandatory. We propose a fast technique for testing samples during the production process in order to evaluate the residual stress distribution after the first phases of mechanical processing. We mapped the stress distribution in PbWO/sub 4/slabs cut from the same production boule. The analysis technique is based on the stress intensity determination using the photo-elastic properties of the samples. The stress distribution is mapped in each sample. The analysis shows that there are regions of high residu...

  8. Separation of PbWO4 and BGO signals into Čerenkov and scintillation components

    Science.gov (United States)

    Voena, C.; DREAM Collaboration

    2009-04-01

    We present results from beam tests performed in 2007 on PbWO4 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 Čerenkov (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, Čerenkov signals have been enhanced with the use of optical filters and the ratio Č/S is measured with good precision (~20-30% for energy deposits less than 1 GeV).

  9. Study of the NaBi(WO4)2 Cerenkov calorimeter

    International Nuclear Information System (INIS)

    Mizuhashi, T.; Watanabe, H.; Ishibashi, S.

    2004-01-01

    A NaBi(WO 4 ) 2 crystal (NBW) is a most promising Cerenkov calorimeter as a photon detector due to its radiation-resistant property. We intend to adopt it as a photon-veto detector in beam-core region for the future rare Kaon decay experiment. However, there is no detail report regarding light yield, which is crucial parameter for our application. Then, a test-beam experiment using electrons and charged pions with momenta from 0.5 to 4.0 GeV/c in the π2 beam line at the 12-GeV PS of KEK was carried out. The light yield was measured to be 286 photoelectrons/GeV-deposition, which meets our requirement. In this report, properties of the NBW, a method and results of the test-beam experiment are presented. (author)

  10. Phase transition in sodium bismuth tungstate NaBi(WO4)2 - acoustic studies

    International Nuclear Information System (INIS)

    Khusravbekov, L.; Charnaya, E.V.; Tien, Cheng; Rakhimov, I.K.; Salakhutdinov, M.I.; Ulfatshoev, M.M.; Borisov, B.F.

    2008-01-01

    Acoustic studies of sodium bismuth tungstate, NaBi(WO 4 ) 2 , single crystal were carried out in the temperature range from 290 K to 340 K. Strong anomalies in ultrasound velocity and attenuation were observed above room temperature for both longitudinal and transverse waves. The results obtained suggested a phase transition at 319.2 K. The order parameter responsible for the phase transition was found to be coupled linearly with strains in transverse acoustic waves and nonlinearly with those in longitudinal waves. It was suggested that the phase transition is related with substitutional ordering of the Na + and Bi 3+ ions at the cation sites. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Polar Order and Frustrated Antiferromagnetism in Perovskite Pb2MnWO6 Single Crystals.

    Science.gov (United States)

    Ivanov, Sergey A; Bush, Alexander A; Stash, Adam I; Kamentsev, Konstantin E; Shkuratov, Valerii Ya; Kvashnin, Yaroslav O; Autieri, Carmine; Di Marco, Igor; Sanyal, Biplab; Eriksson, Olle; Nordblad, Per; Mathieu, Roland

    2016-03-21

    Single crystals of the multiferroic double-perovskite Pb2MnWO6 have been synthesized and their structural, thermal, magnetic and dielectric properties studied in detail. Pure perovskite-phase formation and stoichiometric chemical composition of the as-grown crystals are confirmed by X-ray single-crystal and powder diffraction techniques as well as energy-dispersive X-ray and inductively coupled plasma mass spectrometry. Detailed structural analyses reveal that the crystals experience a structural phase transition from the cubic space group (s.g.) Fm3̅m to an orthorhombic structure in s.g. Pn21a at about 460 K. Dielectric data suggest that a ferrielectric phase transition takes place at that same temperature, in contrast to earlier results on polycrystalline samples, which reported a transition to s.g. Pnma and an antiferroelectric low-temperature phase. Magnetic susceptibility measurements indicate that a frustrated antiferromagnetic phase emerges below 8 K. Density functional theory based calculations confirm that the cationic order between Mn and W is favorable. The lowest total energy was found for an antiferromagnetically ordered state. However, analyses of the calculated exchange parameters revealed strongly competing antiferromagnetic interactions. The large distance between the magnetic atoms, together with magnetic frustration, is shown to be the main reason for the low value of the ordering temperature observed experimentally. We discuss the structure-property relationships in Pb2MnWO6 and compare these observations to reported results on related Pb2BWO6 perovskites with different B cations.

  12. 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

  13. 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.

  14. 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

  15. 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...

  16. 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.

  17. 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

  18. Fabrication of WO3@g-C3N4 with core@shell nanostructure for enhanced photocatalytic degradation activity under visible light

    Science.gov (United States)

    Wang, Pu; Lu, Na; Su, Yan; Liu, Ning; Yu, Hongtao; Li, Jie; Wu, Yan

    2017-11-01

    WO3@g-C3N4 composite photocatalysts with core@shell nanostructure were fabricated via a self-assembly method. A large heterojunction interfacial area of WO3@g-C3N4 can be provided in the nanoscale heterostructure. Furthermore, the electron mobility of the composite photocatalysts was improved with the introduction of WO3. These are favorable for increasing the separation efficiency of photoinduced electron-hole pairs and improving the photocatalytic efficiency of WO3@g-C3N4, which was confirmed by the measurements of photocurrent and electrochemical impedance spectroscopy. The results of the photocatalytic degradation of Rh B showed dramatic photocatalytic performance of this composite photocatalyst. The kinetic constant of Rh B degradation on the WO3@g-C3N4 was 0.95 h-1, which was 7.7-fold and 3.5-fold higher than those on pure WO3 and g-C3N4 nanosheets, respectively. In addition, the stability of the composite photocatalyst was also satisfactory according to the result of the three-cycle experiment.

  19. Sonochemical degradation of methyl orange in the presence of Bi2WO6: Effect of operating parameters and the generated reactive oxygen species.

    Science.gov (United States)

    He, Ling-Ling; Liu, Xian-Ping; Wang, Yong-Xia; Wang, Zhi-Xin; Yang, Yan-Jie; Gao, Yan-Ping; Liu, Bin; Wang, Xin

    2016-11-01

    The Bi2WO6 was prepared by the hydrothermal method and its sonocatalytic activity was studied in the degradation of methyl orange (MO) solutions. The effects of catalytic activity of Bi2WO6 on dye were inspected by the change in absorbance of dye with UV-vis spectrometer. The influences of operational parameters such as the addition amount of Bi2WO6, pH, the initial concentration of dyes, ultrasonic power and irradiation time on the degradation ratio were investigated. In addition, the obtained results indicated that the kinetics of sonochemical reactions of MO were consistent with the pseudo first-order kinetics and Bi2WO6 had excellent reusability and stability during the sonochemical degradation processes. The generation and kinds of reactive oxygen species (ROS) and their influence on the sonochemical degradation of MO were determined by the methods of oxidation-extraction spectrophotometry and ROS scavengers. The results indicate that the degradation of MO in the presence of Bi2WO6 under ultrasonic irradiation is related to the generation of ROS, in which both singlet molecular oxygen ((1)O2) and hydroxyl radical (OH) play important roles in the sonochemical degradation of MO. These experimental results provide a sound foundation for the further development of Bi2WO6 as a sonocatalyst in wastewater treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. 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)

  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. 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.

  3. Highly Efficient Electronic Sensitization of Non-oxidized Graphene Flakes on Controlled Pore-loaded WO3 Nanofibers for Selective Detection of H2S Molecules

    Science.gov (United States)

    Choi, Seon–Jin; Choi, Chanyong; Kim, Sang-Joon; Cho, Hee-Jin; Hakim, Meggie; Jeon, Seokwoo; Kim, Il–Doo

    2015-01-01

    Tailoring of semiconducting metal oxide nanostructures, which possess controlled pore size and concentration, is of great value to accurately detect various volatile organic compounds in exhaled breath, which act as potential biomarkers for many health conditions. In this work, we have developed a very simple and robust route for controlling both the size and distribution of spherical pores in electrospun WO3 nanofibers (NFs) via a sacrificial templating route using polystyrene colloids with different diameters (200 nm and 500 nm). A tentacle-like structure with randomly distributed pores on the surface of electrospun WO3 NFs were achieved, which exhibited improved surface area as well as porosity. Porous WO3 NFs with enhanced surface area exhibited high gas response (Rair/Rgas = 43.1 at 5 ppm) towards small and light H2S molecules. In contrast, porous WO3 NFs with maximized pore diameter showed a high response (Rair/Rgas = 2.8 at 5 ppm) towards large and heavy acetone molecules. Further enhanced sensing performance (Rair/Rgas = 65.6 at 5 ppm H2S) was achieved by functionalizing porous WO3 NFs with 0.1 wt% non-oxidized graphene (NOGR) flakes by forming a Schottky barrier (ΔΦ = 0.11) at the junction between the WO3 NFs (Φ = 4.56 eV) and NOGR flakes (Φ = 4.67 eV), which showed high potential for the diagnosis of halitosis.

  4. Highly efficient perovskite solar cells based on a nanostructured WO3-TiO2 core-shell electron transporting material

    KAUST Repository

    Mahmood, Khalid

    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.

  5. 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.

  6. 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

  7. 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)

  8. ISOTERMA DE LANGMUIR Y FREUNDLICH COMO MODELOS PARA LA ADSORCIÓN DE COMPONENTES DE ÁCIDO NUCLEICO SOBRE WO 3 I LANGMUIR AND FREUNDLICH ISOTHERMS AS MODEL FOR THE ADSORPTION OF NUCLEIC ACID COMPONENTS ON WO 3

    Directory of Open Access Journals (Sweden)

    Carlos F. Rivas

    2014-02-01

    Full Text Available In this paper, we studied the effect of pH (3-10 in the adsorption of nucleic acid constituents; nucleobases, nucleosides and nucleotides, on tungsten trioxide (WO3. Isotherms of Langmuir and Freundlich were used to describe adsorption processes. It was noted that neutral pH favors the adsorption of nucleic acid components. The adsorption date suggests that there is a considerable difference in the binding capacity of the nucleobases and their derivatives on WO3, which depends on the molecular architecture of the adsorbed species. It was found that adsorption of biomolecules onto the catalyst has following sequence: Nucleotide > Nucleoside > Nucleobase. The highest values of the maximum adsorption capacity (Xm were obtained for nucleotides, finding that at pH 7 the CMP'5 (Xm = 64.94 mg/L > UMP'5 (Xm = 54.64 mg/L @ GMP'5 (Xm = 54.35 mg/L > AMP'5 (Xm = 45.05 mg/L. Freundlich constants (KF ranged between 4 and 7. For all pH, nucleosides and nucleotides have values of n (constant of adsorption intensity close to unity, indicating that the active sites of catalyst are energetically equivalent, except the AMP'5 at pH 7 (n = 2.16. The neutral pH is optimum to chemically modify the surface of the WO3.

  9. The effects of sequential annealing in air atmosphere on luminescence properties of PbWO4 single crystal

    International Nuclear Information System (INIS)

    Huang Yanlin; Zhu Wenliang; Feng Xiqi

    2003-01-01

    A PbWO 4 single crystal grown by the modified Bridgeman method was sequentially annealed in air atmosphere from 640 to 1040 deg. C. Optical absorption, X-ray excited luminescence (XEL), and photoluminescence (PL) were measured before and after each step of annealing. This crystal exhibited a complex variety of luminescence in the process of annealing. The exchanges of oxygen components between PbWO 4 and the environment could modify the defects in the crystal and exert a significant influence on optical absorption and luminescence. Interstitial oxygen (O i ) formed in the progress of annealing might have an obvious influence on the luminescence, especially the green component. Possible position of the interstitial oxygen in this Sheelite-type structure was discussed

  10. Structural and spectroscopic comparison between polycrystalline, nanocrystalline and quantum dot visible light photo-catalyst Bi2WO6

    Science.gov (United States)

    Teck, Michael; Murshed, M. Mangir; Schowalter, Marco; Lefeld, Niels; Grossmann, Henrike K.; Grieb, Tim; Hartmann, Thomas; Robben, Lars; Rosenauer, Andreas; Mädler, Lutz; Gesing, Thorsten M.

    2017-10-01

    The structural and spectroscopic features of the visible light photocatalyst Bi2WO6 have been studied. Polycrystalline (PC), nanocrystalline (NC) and quantum dot (QD) sized samples were produced using solid state reaction, hydrothermal and flame spray pyrolysis methods, respectively. While the crystal structures of PC and NC Bi2WO6 are well characterized using X-ray powder diffraction data Rietveld refinements, the structural information of the QD are obtained from the complementary pair distribution function analysis and high-resolution transmission electron microscopy. The Raman spectra of the samples are compared with the phonon density of states calculated by DFT. A continuous phenomenological model describes selective optical phonon confinement into the QDs. The type of the electronic bandgaps obtained from the UV-VIS absorbance-spectra have been analyzed using two different methods, and compared with those calculated from the electronic band structures.

  11. 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.

  12. 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

    . Placental passage of benzoic acid, caffeine, and glyphosate in an ex vivo human perfusion system. J. Toxicol. Environ. Health, Part A 71, 984-991]. In this work, the transport of these same three compounds, plus the reference compound antipyrine, was investigated using BeWo (b30) cell monolayers. Transport......The placental passage of three compounds with different physicochemical properties was recently investigated in ex vivo human placental perfusion experiments (caffeine, benzoic acid, and glyphosate) [Mose, T., Kjaerstad, M.B., Mathiesen, L., Nielsen, J.B., Edelfors, S., Knudsen, L.E., 2008...... 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...

  13. 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

  14. 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.

  15. Nanochemistry-derived Bi2WO6 nanostructures: towards production of sustainable chemicals and fuels induced by visible light.

    Science.gov (United States)

    Zhang, Nan; Ciriminna, Rosaria; Pagliaro, Mario; Xu, Yi-Jun

    2014-08-07

    Low cost and easily made bismuth tungstate (Bi2WO6) could be one of the key technologies to make chemicals and fuels from biomass, atmospheric carbon dioxide and water at low cost using solar radiation as an energy source. Its narrow band gap (2.8 eV) enables ideal visible light (λ > 400 nm) absorption. Yet, it is the material's shape, namely the superstructure morphology wisely created via a nanochemistry approach, which leads to better electron-hole separation and much higher photoactivity. Recent results coupled to the versatile photochemistry of this readily available semiconductor suggest that the practical application of nanochemistry-derived Bi2WO6 nanostructures for the synthesis of value-added fine chemicals and fuel production is possible. We describe progress in this important field of chemical research from a nanochemistry viewpoint, and identify opportunities for further progress.

  16. Effect of solution chemistry on the characteristics of hydrothermally grown WO{sub 3} for electroactive applications

    Energy Technology Data Exchange (ETDEWEB)

    Christou, K. [Mechanical Engineering Department, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Louloudakis, D. [Department of Physics, University of Crete, 710 03 Heraklion, Crete (Greece); Center of Materials Technology and Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Vernardou, D., E-mail: dimitra@iesl.forth.gr [Center of Materials Technology and Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Savvakis, C. [Mechanical Engineering Department, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Katsarakis, N. [Center of Materials Technology and Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Electrical Engineering Department, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Institute of Electronic Structure and Laser, Foundation for Research & Technology-Hellas, P.O. Box 1527, Vassilika Vouton, 711 10 Heraklion, Crete (Greece); Koudoumas, E. [Center of Materials Technology and Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Electrical Engineering Department, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Kiriakidis, G. [Department of Physics, University of Crete, 710 03 Heraklion, Crete (Greece); Institute of Electronic Structure and Laser, Foundation for Research & Technology-Hellas, P.O. Box 1527, Vassilika Vouton, 711 10 Heraklion, Crete (Greece)

    2015-11-02

    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{sup −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{sub 3} coatings with controlled properties. • The choice of metal sulfate is important in determining their properties. • Flower-like hexagonal WO{sub 3} structures for electroactive applications.

  17. 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.)

  18. 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...

  19. Kehidupan Take Seiji sebagai Freeter yang Tercermin dalam Drama Freeter, Ie Wo Kau Karya Sutradara Kono Keita dan Joho Hidenori

    OpenAIRE

    NURRITRI, SECTIA ANANDYNI

    2014-01-01

    Nurritri, Sectia Anandyni. 2014. Kehidupan Take Seiji Sebagai Freeter yang Tercermin dalam Drama Freeter, Ie wo Kau Karya Sutradara Kono Keita dan Joho Hidenori. Program Studi Sastra Jepang, Universitas Brawijaya. Pembimbing: (1) Eka Marthanty Indah Lestari. (2) Dewi Puspitasari.Kata Kunci: drama, sosiologi sastra, freeter, masyarakat JepangKarya sastra adalah gambaran Kenyataan dari suatu peristiwa yang terjadi di masyarakat. Salah satu bentuk karya sastra adalah drama. Penelitian ini mengg...

  20. 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

  1. 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.

  2. Photo- and radioluminescent properties of undoped and Bi-doped Lu{sub 2}WO{sub 6} powders at 10–300 K

    Energy Technology Data Exchange (ETDEWEB)

    Madej, A., E-mail: anna.madej@chem.uni.wroc.pl [Faculty of Chemistry, University of Wroclaw, 14F. Joliot-Curie Street, 50-383 Wroclaw (Poland); Wroclaw Research Centre EIT+, 147 Stablowicka Street, 54-066 Wroclaw (Poland); Witkowski, M.E., E-mail: mwit@fizyka.umk.pl [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, 5/7 Grudziądzka Street, 87-100 Torun (Poland); Wojtowicz, A.J., E-mail: andywojt@fizyka.umk.pl [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, 5/7 Grudziądzka Street, 87-100 Torun (Poland); Zych, E., E-mail: eugeniusz.zych@chem.uni.wroc.pl [Faculty of Chemistry, University of Wroclaw, 14F. Joliot-Curie Street, 50-383 Wroclaw (Poland); Wroclaw Research Centre EIT+, 147 Stablowicka Street, 54-066 Wroclaw (Poland)

    2015-04-15

    Undoped and Bi{sup 3+}-doped lutetium oxytungstate (Lu{sub 2}WO{sub 6}) powder materials were prepared by a solid state reaction method at selected temperatures between 1000 and 1400 °C. The structural, radio- and photoluminescent properties of these materials were investigated. Upon Bi activation, red-shifts of both emission and excitation bands are observed. While a broad emission band characteristic of undoped Lu{sub 2}WO{sub 6} and resulting from a charge transfer transition of the tungstate group WO{sub 6} peaks at 450 nm, the Bi{sup 3+}-activated Lu{sub 2}WO{sub 6} shows a broad band emission peaking at about 510 nm. This emission can be related to the transition between excited and ground states of a deep Bi donor. The ground state of this donor corresponds to an electron-occupied Bi-level at about 0.45 eV above the top of the valence band. Both compositions generate bright radioluminescence upon X-ray excitation at low temperatures. For Lu{sub 2}WO{sub 6}:Bi the radioluminescence efficiency is roughly stable in the range between 10 and 250 K, while undoped Lu{sub 2}WO{sub 6} suffers from moderate thermal quenching above 10 K. The fraction of total radioluminescence due to Bi contribution in Lu{sub 2}WO{sub 6}:Bi increases from 0.19 at 10 K to 0.53 at room temperature. A simple configuration coordinate diagram is introduced in order to illustrate and describe the charge carrier recombination and light generation mechanism in these materials. - Highlights: • Radio- and photoluminescent properties of Lu{sub 2}WO{sub 6} and Lu{sub 2}WO{sub 6}:Bi were investigated in 10–300 K. • Model of the spectroscopic properties together with configuration coordinate diagram was proposed. • Contributions from Bi and WO6 group to total radio- and photoluminescence was calculated at 10 K and RT.

  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. Characterization of magnetic properties of Sr2CuWO6 and Sr2CuMoO6

    Science.gov (United States)

    Vasala, Sami; Saadaoui, Hassan; Morenzoni, Elvezio; Chmaissem, Omar; Chan, Ting-Shan; Chen, Jin-Ming; Hsu, Ying-Ya; Yamauchi, Hisao; Karppinen, Maarit

    2014-04-01

    In this work we examine the low-temperature magnetic properties of the two double-perovskite compounds Sr2CuWO6 and Sr2CuMoO6 using magnetic susceptibility, muon spin rotation and relaxation, and neutron powder diffraction measurements. Additionally, the most relevant spin exchange interaction constants are derived from ab initio electronic structure calculations, aided by x-ray absorption spectroscopy. The compounds exhibit quasi-two-dimensional magnetic properties, with broad maxima at Tmax = 83 and 95 K for Sr2CuWO6 and Sr2CuMoO6, respectively. However, three-dimensional long-range order takes place below TN = 24(1) and 28(2) K for Sr2CuWO6 and Sr2CuMoO6, respectively. Our results show that the low-dimensional magnetic correlations are mainly due to the significant next-nearest-neighbor interactions in the ab plane of the double-perovskite structure, whereas three-dimensional long-range magnetic order is caused by weaker next-nearest-neighbor interactions along the c axis. Next-nearest-neighbor interactions are also slightly frustrated by weaker nearest-neighbor interactions within the ab plane. Based on these results we predict the low-temperature magnetic structure in these compounds to be type-II antiferromagnetic order of the double-perovskite lattice.

  7. 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.

  8. 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.)

  9. 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

  10. Facile synthesis of PbWO4: applications in photoluminescence and photocatalytic degradation of organic dyes under visible light.

    Science.gov (United States)

    Saraf, Rohit; Shivakumara, C; Behera, Sukanti; Nagabhushana, H; Dhananjaya, N

    2015-02-05

    Stolzite polymorph of PbWO4 catalyst was prepared by the facile room temperature precipitation method. Structural parameters were refined by the Rietveld analysis using powder X-ray data. PbWO4 was crystallized in the scheelite-type tetragonal structure with space group I41/a (No. 88). Field emission scanning electron microscopy revealed leaf like morphology. Photoluminescence spectra exhibit broad blue emission (425 nm) under the excitation of 356 nm. The photocatalytic degradation of Methylene blue, Rhodamine B and Methyl orange dyes were measured under visible illumination. The 100% dye degradation was observed for MB and RhB dyes within 60 and 105 min. The rate constant was found to be in the decreasing order of MB>RhB>MO which followed the 1st order kinetic mechanism. Therefore, PbWO4 can be a potential candidate for blue component in white LEDs and also acts as a catalyst for the treatment of toxic and non-biodegradable organic pollutants in water. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Wafer-scaled monolayer WO3 windows ultra-sensitive, extremely-fast and stable UV-A photodetection

    Science.gov (United States)

    Hai, Zhenyin; Akbari, Mohammad Karbalaei; Xue, Chenyang; Xu, Hongyan; Hyde, Lachlan; Zhuiykov, Serge

    2017-05-01

    The monolayer WO3-based UV-A photodetectors, fabricated by atomic layer deposition (ALD) technique at the large area of SiO2/Si wafer, have demonstrated vastly improved functional capabilities: extremely fast response time of less than 40 μs and photoresponsivity reaching of ∼0.329 A W-1. Their ultrafast photoresponse time is at least 400-fold improvement over the previous reports for any other WO3-based UV photodetectors that have ever been fabricated, and significantly faster than most of other photodetectors based on two-dimensional (2D) nanomaterials reported-to-date. Moreover, their measured long-term stability exceeds more than 200 cycles without any visible degradation. The ALD-deposited WO3 monolayer has also exhibited wider bandgap of 3.53 eV and the UV-A photodetector based on it is environmentally friendly, highly reliable, with excellent reproducibility and long-term stability. Thus, the shift to mono-layered semiconductors, which possess completely new quantum-confined effects, has the greatest potential in creating a new class of nano-materials, which in return windows new functional opportunities for various opto-electronic instruments built on semiconductor monolayer and, more importantly, can result in new strategy for fabrication highly-flexible, inexpensive and extremely-sensitive devices. This strategy also opens up the great opportunities for industrialization and commercialization of the photodetectors and other optoelectronic devices based on monolayer or few-layered 2D nanomaterials.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Synthesis, Characterization, and Low Temperature Sintering of Nanostructured BaWO4 for Optical and LTCC Applications

    Directory of Open Access Journals (Sweden)

    S. Vidya

    2013-01-01

    Full Text Available Synthesis of nano-BaWO4 by a modified combustion technique and its suitability for various applications are reported. The structure and phase purity of the sample analyzed by X-ray diffraction, Fourier transform Raman, and infrared spectroscopy show that the sample is phase pure with tetragonal structure. The particle size from the transmission electron microscopy is 22 nm. The basic optical properties and optical constants of the nano BaWO4 are studied using UV-visible absorption spectroscopy which showed that the material is a wide band gap semiconductor with band gap of 4.1 eV. The sample shows poor transmittance in ultraviolet region while maximum in visible-near infrared regions. The photoluminescence spectra show intense emission in blue region. The sample is sintered at low temperature of 810°C, without any sintering aid. Surface morphology of the sample is analyzed by scanning electron microscopy. The dielectric constant and loss factor measured at 5 MHz are 9 and 1.56×10-3. The temperature coefficient of dielectric constant is −22 ppm/°C. The experimental results obtained in the present work claim the potential use of nano BaWO4 as UV filters, transparent films for window layers on solar cells, antireflection coatings, scintillators, detectors, and for LTCC applications.

  17. Effect of WO 3 on the spectroscopic properties in Er 3+/Yb 3+ co-doped bismuth-borate glasses

    Science.gov (United States)

    Wang, Jun; Zhou, Yaxun; Dai, Shixun; Xu, Tiefeng; Nie, Qiuhua

    2007-11-01

    The spectroscopic properties of Er 3+/Yb 3+ co-doped Bi 2O 3-B 2O 3-WO 3 (BBW) glasses were analyzed and discussed. The effect of WO 3 content on the absorption spectra, the Judd-Ofelt parameters Ω t ( t=2, 4, 6), emission spectra and the lifetime of the 4I 13/2 level and the quantum efficiency of Er 3+: 4I 13/2→ 4I 15/2 transition were also investigated. With the substitution of WO 3 for B 2O 3, the measured lifetime of the 4I 13/2 level and the quantum efficiency of Er 3+: 4I 13/2→ 4I 15/2 transition increase from 0.98 to 1.31 ms and from 38.2% to 49.2%, respectively. The effective width of emission band and the emission cross-section both decrease slightly. And the emission spectra is analyzed via the different curve ( σe- σa) of BBW glasses, the influence of OH - is also discussed.

  18. Hydrothermal Synthesis and Up-Conversion Luminescence of Yb3+/Ho3+ Co-doped Y6WO12 Nanocrystals

    Science.gov (United States)

    Rao, Weifeng; Zhu, Qiansheng; Ren, Qiang; Wu, Chenchen; Miao, Juhong

    2017-08-01

    Yb3+/Ho3+ co-doped Y6WO12 nanocrystals with different concentrations of Ho3+ ions have been synthesized through a facile hydrothermal method followed by a subsequent heat treatment. The nanostructures, morphologies, and up-conversion luminescent properties of the as-prepared Y6WO12:Yb3+/Ho3+ nanocrystals were investigated by powder x-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence spectra. XRD results indicate that all the diffraction peaks of the samples match well with the cubic phase of Y6WO12. SEM images demonstrate that the samples consist of spherical-like nanoparticles ranging in size from about 30 nm to 50 nm, which increases slightly with the increase of sintering temperature. Under the excitation of a 980 nm diode laser, the as-prepared nanocrystals show bight red and green luminescence, which is attributed to the transition of 5F5 → 5I8 and 5F4, 5S2 → 5I8 of Ho3+, respectively. With the elevation of the heat treatment temperature from 700°C to 900°C, the up-conversion emission intensity goes up significantly. Additionally, the decay lifetimes data follow a bi-exponential nature. Both the emission intensity (red and green) and their corresponding decay lifetimes increase with increasing Ho3+ concentration, maximizing at 1.0 mol.%, and then decrease, which is mainly attributed to the concentration quenching effect.

  19. 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.

  20. Comparative description of magnetic interactions in Sr2CuTeO6 and Sr2CuWO6

    Science.gov (United States)

    Xu, Yuanhui; Liu, Shanshan; Qu, Nianrui; Cui, Yanli; Gao, Qiangqiang; Chen, Rongna; Wang, Jing; Gao, Faming; Hao, Xianfeng

    2017-03-01

    In this work, we comparatively explored the electronic structure and the low-dimensional magnetic interactions of double-perovskite compounds Sr2CuTeO6 and Sr2CuWO6 through first-principles calculations. The electronic structure calculations indicate that the Cu2+ (3d 9) site is the only magnetic active one, whereas Te6+ and W6+ remain in nonmagnetic states with d 10 and d 0 electronic configurations, respectively. The magnetic exchange interactions have been evaluated on the basis of the classical Heisenberg model. Both Sr2CuTeO6 and Sr2CuWO6 should be strong frustrated 2D magnetism, in excellent agreement with the experimental observations. Nevertheless, the nearest-neighbor antiferromagnetic interaction J 1 plays a determined role in constructing the Néel antiferromagnetic ordering within the square Cu2+ framework of Sr2CuTeO6. While, the next-nearest-neighbor antiferromagnetic interaction J 2 transcends the nearest-neighbor interaction J 1, establishes the collinear antiferromagnetic ordering in Sr2CuWO6. The discrimination has been explored and analyzed in detail using density of states, charge density as well as spin density analysis.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Non-noble metal Bi deposition by utilizing Bi{sub 2}WO{sub 6} as the self-sacrificing template for enhancing visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Shixin [Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Zhang, Yihe, E-mail: zyh@cugb.edu.cn [Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Li, Min [Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Du, Xin [Research Center for Bioengineering and Sensing Technology, Department of Chemistry& Biological Engineering, University of Science & Technology Beijing, Beijing 100083 (China); Huang, Hongwei, E-mail: hhw@cugb.edu.cn [Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China)

    2017-01-01

    Highlights: • Bi metal deposited Bi{sub 2}WO{sub 6} photocatalyst is synthesized via an in-situ reduction. • The light absorption of Bi{sub 2}WO{sub 6} is enhanced by Bi metal. • Charge separation efficiency of Bi{sub 2}WO{sub 6} is increased by Bi metal. • Bi-Bi{sub 2}WO{sub 6} shows highly promoted photocatalytic activity for phenol degradation. - Abstract: Bi metal deposited on Bi{sub 2}WO{sub 6} composite photocatalysts have been successfully synthesized via a simple in-situ reduction method at room temperature with using Bi{sub 2}WO{sub 6} as self-sacrificing template and NaBH{sub 4} as reducing agent. The reduction extent can be easily modulated by controlling the concentration of NaBH{sub 4} solution. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) spectra, N{sub 2} adsorption-desorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), diffuse reflection spectroscopy (DRS) and photoelectrochemical measurements were carried out to analyze the phase, morphology, optical property and photoelectrochemical property of the as-prepared samples. The photocatalytic activity is surveyed by degradation of phenol under visible light (λ > 420 nm), which showed that the BWO-0.2 photocatalyst exhibited the highest efficiency, which was over 3 times as high as pure Bi{sub 2}WO{sub 6}. The enhanced photocatalytic activity should be attributed to strengthened photoabsorption and charge separation efficiency derived from the surface plasmon resonance (SPR) of Bi metal.

  7. 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

  8. Characterization of WO3-SnO2 Nanocomposites and Application in Humidity Sensing

    Directory of Open Access Journals (Sweden)

    N. K. Pandey

    2011-02-01

    Full Text Available Pellet samples of WO3-SnO2 nanocomposite in the weight % ratio of 85:15 have been prepared and annealed at temperatures 300-600 °C for 3 hours. When exposed to humidity, the sample shows maximum sensitivity of 23.41 MΩ/%RH for the annealing temperature 600 °C. For this annealing temperature of 600 °C, the sample shows low ageing effect after four months. The hysteresis (between humidification and desiccation, measured in the RH range of 15–90 % RH for the annealing temperature of 600 °C is less than 8 % RH. Activation energy measured from Arrhenius plot in 50 to 300 °C and 300 to 600 °C range have been found to be 0.12 and 0.54 eV respectively. The response time and recovery time for the sample annealed at 600 °C are 121 seconds and 912 seconds respectively. The grain size and crystallite size of the pellets are found to be in the nanometer range. An observation of the crystallite size and grain size would suggest that smaller crystallites are getting agglomerated to form larger grains.

  9. Rottlerin-mediated inhibition of Toxoplasma gondii growth in BeWo trophoblast-like cells.

    Science.gov (United States)

    Ietta, Francesca; Maioli, Emanuela; Daveri, Elena; Gonzaga Oliveira, Juliana; da Silva, Rafaela José; Romagnoli, Roberta; Cresti, Laura; Maria Avanzati, Anna; Paulesu, Luana; Barbosa, Bellisa de Freitas; Gomes, Angelica de Oliveira; Roberto Mineo, José; Ferro, Eloisa Amália Vieira

    2017-04-28

    Autophagy is a crucial and physiological process for cell survival from yeast to mammals, including protozoan parasites. Toxoplasma gondii, an intracellular parasite, typically exploits autophagic machinery of host cell; however host cell upregulates autophagy to combat the infection. Herein we tested the efficacy of Rottlerin, a natural polyphenol with autophagic promoting properties, against Toxoplasma infection on the chorioncarcinoma-derived cell line BeWo. We found that Rottlerin, at sub-toxic doses, induced morphological and biochemical alterations associated with autophagy and decreased Toxoplasma growth in infected cells. Although autophagy was synergically promoted by Toxoplasma infection in combination with Rottlerin treatment, the use of the autophagy inhibitor chloroquine revealed that Rottlerin anti-parasitic effect was largely autophagy-independent and likely mediated by the converging inhibitory effect of Rottlerin and Toxoplasma in host protein translation, mediated by mTOR inhibition and eIF2α phosphorylation. Both events, which on one hand could explain the additive effect on autophagy induction, on the other hand led to inhibition of protein synthesis, thereby depriving Toxoplasma of metabolically essential components for multiplication. We suggest that modulation of the competition between pathogen requirement and host cell defense might be an attractive, novel therapeutic approach against Toxoplasma infection and encourage the development of Rottlerin-based new therapeutic formulations.

  10. Switching of a spin-spiral-induced polarization in multiferroic MnWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, Tim; Meier, Dennis; Fiebig, Manfred [HISKP, Universitaet Bonn (Germany); Becker-Bohaty, Petra; Bohaty, Ladislav [Institut fuer Kristallographie, Universitaet zu Koeln (Germany)

    2010-07-01

    Coexisting ferroic orders become interesting when there is an interaction between them. Especially applying an electric field and thus changing the magnetic order is highly desirable for possible applications. In spite of the declared interest in multiferroics to switch a magnetization by an electric field nothing is known about the dynamics of the actual switching process. The coupling of ferroelectric and magnetic order is intrinsically strong in spin-spiral multiferroics, where ferroelectricity emerges as a consequence of complex magnetic long-range order. Here we observe the manipulation of magnetically-induced ferroelectric domains in MnWO{sub 4} by optical second harmonic generation (SHG). Application of an electric field allows to transform the sample to an electric as well as magnetic single-domain state. Moreover we obtained images of the domain structures during the transition revealing the growth of the domains. When cooled in zero-field, the domains have a bubble-like topology. Interestingly, after recovery from a single domain state the shape changes to a stripe structure and the domain size is significantly increased. Effects of the shape and duration of the electric-field poling pulses are investigated. Furthermore, in contrast to typical ionic ferroelectrics the spontaneous polarization can be switched without fatigue - no defects or pinning effects constrain the movement of domain walls.

  11. 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.

  12. Breath acetone monitoring by portable Si:WO3 gas sensors

    Science.gov (United States)

    Righettoni, Marco; Tricoli, Antonio; Gass, Samuel; Schmid, Alex; Amann, Anton; Pratsinis, Sotiris E.

    2013-01-01

    Breath analysis has the potential for early stage detection and monitoring of illnesses to drastically reduce the corresponding medical diagnostic costs and improve the quality of life of patients suffering from chronic illnesses. In particular, the detection of acetone in the human breath is promising for non-invasive diagnosis and painless monitoring of diabetes (no finger pricking). Here, a portable acetone sensor consisting of flame-deposited and in situ annealed, Si-doped epsilon-WO3 nanostructured films was developed. The chamber volume was miniaturized while reaction-limited and transport-limited gas flow rates were identified and sensing temperatures were optimized resulting in a low detection limit of acetone (~20 ppb) with short response (10–15 s) and recovery times (35–70 s). Furthermore, the sensor signal (response) was robust against variations of the exhaled breath flow rate facilitating application of these sensors at realistic relative humidities (80–90%) as in the human breath. The acetone content in the breath of test persons was monitored continuously and compared to that of state-of-the-art proton transfer reaction mass spectrometry (PTR-MS). Such portable devices can accurately track breath acetone concentration to become an alternative to more elaborate breath analysis techniques. PMID:22790702

  13. 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.

  14. 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.

  15. Bi2WO6 nanoflowers: An efficient visible light photocatalytic activity for ceftriaxone sodium degradation

    Science.gov (United States)

    Zhao, Yanyan; Wang, Yongbo; Liu, Enzhou; Fan, Jun; Hu, Xiaoyun

    2018-04-01

    The morphology-controlled synthesis of nano-structure photocatalyst have leaded a new possibility to improve their physical and chemical properties. Herein, Bi2WO6 nanocrystals (BWO) with nano-flower, nano plates, knot shape, rod like and irregular morphologies have been successfully synthesized through a highly facile hydrothermal process by simply adjusting pH values, reactive solvents and temperature. Photocatalytic activity of the as-prepared samples were evaluated by degradation of Ceftriaxone sodium under visible light irradiation (λ > 420 nm), the results indicated that all the BWO samples exhibit morphology-associated photocatalytic activity, and the 3D flowerlike-structure of BWO composed of well-ordered nano plates (BWO-D-5) displayed the outstanding photocatalytic activity. Through getting insight into the mechanism, h+ and rad O2- play major roles compared with rad OH in photocatalytic degradation process. The possible pathway of Ceftriaxone sodium and the intermediates were proposed to better understand the reaction process. Moreover, this work not only provides an example of morphology-dependent photocatalytic activity of BWO but also provides an illustrative example for removing organic pollutant molecules according to practical requirements.

  16. 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.

  17. 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.

  18. On-line monitoring of CO2 quality using doped WO3 thin film sensors

    International Nuclear Information System (INIS)

    Stankova, M.; Vilanova, X.; Llobet, E.; Calderer, J.; Vinaixa, M.; Gracia, I.; Cane, C.; Correig, X.

    2006-01-01

    Thin films of either pure or doped tungsten oxide were grown by radiofrequency (rf) sputtering onto silicon micromachined substrates. Up to 7 different dopant materials (noble metals or metal oxides) were deposited by rf sputtering or by evaporation onto the tungsten oxide films. The responsiveness of the resulting micromachined sensors towards sulfur dioxide and hydrogen sulfide was studied. Other pollutants in CO 2 such as ethylene and methane were also tested. It was found that Au-doped tungsten oxide sensors were highly sensitive to H 2 S, poorly sensitive to SO 2 and almost insensitive to hydrocarbons. On the other hand, Pt-doped tungsten oxide was highly sensitive to SO 2 , poorly responsive to H 2 S and nearly insensitive to hydrocarbons. By applying a principal component analysis (PCA), we show that it would be possible to selectively detect traces of H 2 S and SO 2 in a CO 2 stream using doped WO 3 microsensors. These sensors could be used in a low-cost analyzer of beverage-grade CO 2

  19. Investigation of thermal and optical properties of thin WO3 films by the photothermal Deflection Technique

    International Nuclear Information System (INIS)

    Gaied, I; Yacoubi, N; Dabbous, S; Nasrallah, T Ben

    2010-01-01

    Owing to its novel physical properties, as well as its technological implication in many fields, the thermal and optical properties of WO 3 thin films are studied here. These thin films are prepared from Ammonium Tungstate and deposited on a glass substrate at 400 0 C by the Spray Pyrolysis Technique. The thermal properties (Thermal conductivity and thermal diffusivity) were studied by the Photothermal Deflection method in its uniform heating case instead of traditionally a non uniform heating one by comparing the experimental amplitude and phase variations versus square root modulation frequency to the corresponding theoretical ones. The best coincidence between theory and experience is obtained for well-defined values of thermal conductivity and thermal diffusivity. The optical properties (optical absorption spectrum and gap energy) were measured using the Photothermal Deflection Spectroscopy (PDS) by drawing the amplitude and phase variation versus wavelength in experimental way and versus absorption coefficient in theoretical one at a fixed modulation frequency. By comparing point by point the normalised experimental and corresponding theoretical amplitude variation, one can deduce the optical absorption spectrum. Using the Tauc law for energies above the gap we can deduce the gap energy. We notice that these films show low thermal conductivity and high transparency in the visible range.

  20. PPAR-γ Regulates Trophoblast Differentiation in the BeWo Cell Model

    Directory of Open Access Journals (Sweden)

    Khrystyna Levytska

    2014-01-01

    Full Text Available Common pregnancy complications, such as severe preeclampsia and intrauterine growth restriction, disrupt pregnancy progression and impair maternal and fetal wellbeing. Placentas from such pregnancies exhibit lesions principally within the syncytiotrophoblast (SCT, a layer in direct contact with maternal blood. In humans and mice, glial cell missing-1 (GCM-1 promotes differentiation of underlying cytotrophoblast cells into the outer SCT layer. GCM-1 may be regulated by the transcription factor peroxisome proliferator-activated receptor-gamma (PPAR-γ; in mice, PPAR-γ promotes labyrinthine trophoblast differentiation via Gcm-1, and, as we previously demonstrated, PPAR-γ activation ameliorates disease features in rat model of preeclampsia. Here, we aimed to characterize the baseline activity of PPAR-γ in the human choriocarcinoma BeWo cell line that mimics SCT formation in vitro and modulate PPAR-γ activity to study its effects on cell proliferation versus differentiation. We report a novel negative autoregulatory mechanism between PPAR-γ activity and expression and show that blocking PPAR-γ activity induces cell proliferation at the expense of differentiation, while these remain unaltered following treatment with the agonist rosiglitazone. Gaining a deeper understanding of the role and activity of PPAR-γ in placental physiology will offer new avenues for the development of secondary prevention and/or treatment options for placentally-mediated pregnancy complications.

  1. Effect of particle size and morphology on the properties of luminescence in ZnWO4

    International Nuclear Information System (INIS)

    Lisitsyn, V.M.; Valiev, D.T.; Tupitsyna, I.A.; Polisadova, E.F.; Oleshko, V.I.; Lisitsyna, L.A.; Andryuschenko, L.A.; Yakubovskaya, A.G.; Vovk, O.M.

    2014-01-01

    We investigated pulsed photoluminescence and pulsed cathodoluminescence in ZnWO 4 crystals and composite materials based on dispersed powders of zinc tungstate in the polymer matrix. It is shown that the size of crystal particles affects the luminescence decay time in excitation by electron and laser radiation. The decay time obtained for the composite material with nanoparticles 25 nm and 100 nm in size is equal to 5 µs and 7 µs, respectively. Relative values of the light yield of composite containing zinc tungstate crystals in the form of rods are found to be larger in comparison with crystallites in the form of grains. The mechanisms of luminescence recombination in laser and electron excitation are discussed. - Highlights: • Pulsed photoluminescence and pulsed cathodoluminescence spectra and decay kinetics of nano- and microcrystals of zinc tungstate in the organosilicic matrix compared to a single crystal were studied. • The luminescence decay kinetics and life-time of the excited state depend on the size of particles in the composite materials and on the type of excitation. • The probability of excitation of luminescence centers responsible for the band at 490 nm is higher which is apparently due to the larger capture cross-section and quantum yield

  2. Optical spectroscopy of Eu3+ ions doped in KLu(WO4)2 single crystals

    International Nuclear Information System (INIS)

    Koubaa, T.; Dammak, M.; Pujol, M.C.; Aguiló, M.; Díaz, F.

    2015-01-01

    Europium single doped potassium lutetium tungstate Eu 3+ :KLu(WO 4 ) 2 single crystals have been grown with the top seeded solution growth slow cooling method. Their absorption spectra are studied in detail for principal light polarizations, E||N p , N m and N g at room and low temperatures. The absorption oscillator strengths parameters are calculated by means of the theory of f–f transition intensities for systems with anomalously strong configuration interaction and by Judd–Ofelt theory. The Ω t (t=2, 4, 6) intensity parameters, and the {O dk , O ck , Δ d , Δ c1 and Δ c2 } (k=1, 2, 3) ASCI parameters are calculated. The radiative transition rates A R , radiative lifetimes τ R , and fluorescent branching ratios β R associated with 5 D 0 – 7 F J transitions of Eu 3+ were determined. The calculated decay times are discussed and compared with experimental values. - Highlights: • Absorption spectra of Eu:KLuW are investigated with respect to principal light polarizations. • Spectroscopic properties of Eu:KLuW are modeled within conventional Judd–Ofelt and (ASCI) theories. • 5 D 0 multiplet shows the contribution of a NR processes and an ET between the Eu 3+ ions. • It is suggested that the Eu 3+ :KLuW is a potential host material for optical applications.

  3. CdWO sub 4 scintillator as a compact gamma ray spectrometer for planetary lander missions

    CERN Document Server

    Eisen, Y; Starr, R; Trombka, J I

    2002-01-01

    The objective of this work is to develop a gamma ray spectrometer (GRS) suitable for use on planetary rover missions. The main characteristics of this detector are low weight, small volume low power and resistance to cosmic ray radiation over a long period of time. We describe a 3 cm diameter by 3 cm thick CdWO sub 4 cylindrical scintillator coupled to a PMT as a GRS for the energy region 0.662-7.64 MeV. Its spectral performance and efficiency are compared to that of a CsI(Tl) scintillator 2.5 cm diameter by 6 cm thick coupled to a 28 mmx28 mm PIN photodiode. The comparison is made experimentally using sup 1 sup 3 sup 7 Cs, sup 6 sup 0 Co, 6.13 MeV gamma rays from a sup 1 sup 3 C(alpha,gamma n)O sup 1 sup 6 * source, 7.64 MeV thermal neutron capture gamma rays emitted from iron bars using a sup 2 sup 5 sup 2 Cf neutron source, and natural radioactivity 1.46 MeV sup 4 sup 0 K and 2.61 MeV sup 2 sup 3 sup 2 Th gamma rays. We use a Monte Carlo method to calculate the total peak efficiency of these detectors and ...

  4. Template-free synthesis of ZnWO{sub 4} powders via hydrothermal process in a wide pH range

    Energy Technology Data Exchange (ETDEWEB)

    Hojamberdiev, Mirabbos, E-mail: mirabbos_uz@yahoo.com [Shaanxi Key Laboratory of Nano-materials and Technology, Xi' an University of Architecture and Technology, Xi' an 710055 (China); Zhu, Gangqiang [School of Physics and Information Technology, Shaanxi Normal University, Xi' an 710062 (China); Xu, Yunhua [Shaanxi Key Laboratory of Nano-materials and Technology, Xi' an University of Architecture and Technology, Xi' an 710055 (China)

    2010-12-15

    ZnWO{sub 4} powders with different morphologies were fabricated through a template-free hydrothermal method at 180 {sup o}C for 8 h in a wide pH range. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible and luminescence spectrophotometers were applied to study the effects of pH values on crystallinity, morphology, optical and luminescence properties. The XRD results showed that the WO{sub 3} + ZnWO{sub 4}, ZnWO{sub 4}, and ZnO phases could form after hydrothermal processing at 180 {sup o}C for 8 h with the pH values of 1, 3-11, and 13, respectively. The SEM and TEM observation revealed that the morphological transformation of ZnWO{sub 4} powders occurred with an increase in pH values as follows: star anise-, peony-, and desert rose-like microstructures and soya bean- and rod-like nanostructures. The highest luminescence intensity was found to be in sample consisting of star anise-like crystallites among all the samples due to the presence of larger particles with high crystallinity resulted from the favorable pH under the current hydrothermal conditions.

  5. Fabrication and Enhanced Visible-light Photocatalytic Activity of Pt/Bi2WO6 Composite with Hierarchical Flower-like Structure

    Science.gov (United States)

    Yi, Wentao; Yan, Chunyan; Ma, Jie; Jie; Xiong

    2017-12-01

    Visible light activated Bi2WO6 was synthesized by the precipitation method with hydrothermal techniques firstly. And then a series of Pt/Bi2WO6 composite micro-flowers (Pt mass concentration: 0.5%, 1.0%, 1.5%, 2.0%) assembled by Bi2WO6 nano-sheets were synthesized by photo-deposition method. The products were characterized by X-ray diffraction (XRD), UV-vis diffusion absorption spectroscopy (DRS), high resolution scanning electron microscopy (HRSEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the products was evaluated by degradation of rhodamine B (RhB) under a Xenon lamp irradiation (λ>420nm). The results showed that sample synthesized at 180°C for 12h (pH=4) had a 3D hierarchical flower-like structure and excellent photocatalytic activity. After photo-deposition of Pt on the surface, the morphology of the sample did not change obviously. However, its photocatalytic activity was greatly enhanced. The products with 1.0% mass ratio of Pt to Bi2WO6 exhibited the highest RhB degradation of 86.5% under visible light irradiation in 120 min, much higher than that of pure Bi2WO6 with RhB degradation of 36.4%. The stability test showed that no obvious loss of photocatalytic activity of the product was detected after four cycles.

  6. Photocatalytic degradation of metronidazole and methylene blue by PVA-assisted Bi2WO6-CdS nanocomposite film under visible light irradiation

    Science.gov (United States)

    Rajendran, Ranjith; Varadharajan, Krishnakumar; Jayaraman, Venkatesan; Singaram, Boobas; Jeyaram, Jayaprakash

    2018-02-01

    The enhanced photocatalytic performance of nanocomposite is synthesized via the hydrothermal method and characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS) and photoluminescence spectroscopy (PL). Under visible light irradiation, PVA assisted Bi2WO6-CdS nanocomposite film displayed enhanced photocatalytic efficiency and inhibition of photocorrosion as compared with pure CdS, pure Bi2WO6 and Bi2WO6-CdS composite. The PVA assisted Bi2WO6-CdS composite film catalyst showed stable catalytic performance until seven successive runs with 92% of methylene blue(MB) degradation, and easy to recover after degradation of organic pollutant. PVA assisted Bi2WO6-CdS nanocomposite film has optimal band edge position for superior photocatalytic degradation. Furthermore, the trapping experiment was carried out using different scavenger for active species. Among the active species, OH· are the most responsive species which play a vital role in the degradation of metronidazole and MB.

  7. WO3/g-C3N4 composites: one-pot preparation and enhanced photocatalytic H2 production under visible-light irradiation

    Science.gov (United States)

    Cheng, Cheng; Shi, Jinwen; Hu, Yuchao; Guo, Liejin

    2017-04-01

    A series of WO3/g-C3N4 composites with different WO3 contents were prepared via a facile one-pot pyrolysis method, and showed notably enhanced visible-light-driven photocatalytic H2-evolution activities, with the highest rate of 400 μmol h-1 gcat -1 that was 15.0 times of that for pristine g-C3N4. Contents and sizes of WO3 crystallites in the composites were easily adjusted by changing the molar ratios of (NH4)2WS4 to C3H6N6 in the feed reagents, thereby successfully optimizing the Z-scheme system constructed by WO3 and g-C3N4 and thus effectively reducing the recombination of photogenerated charge carriers in g-C3N4. Moreover, pore volumes and surface areas of the composites were gradually enlarged by introducing WO3 into g-C3N4 via the one-pot preparation strategy, therefore promoting the redox reactions to evolve H2. This work presented an effective route to simultaneously optimize the phase compositions and textural structures of photocatalysts for enhanced H2 evolution.

  8. Effects of different petal thickness on gas sensing properties of flower-like WO3·H2O hierarchical architectures

    International Nuclear Information System (INIS)

    Zeng, Wen; Zhang, He; Wang, Zhongchang

    2015-01-01

    Graphical abstract: In this work, we prepare four different petal thicknesses of hierarchical WO 3 ·H 2 O architectures via a simple hydrothermal process, and systematically report their formation mechanisms and gas-sensing properties. - Highlights: • Flower-like WO 3 ·H 2 O architectures with different petal thickness were reported. • The WO 3 ·H 2 O sheet-flower sensor shows a significantly enhanced gas response. • A possible growth mechanism for the flower-like architectures is proposed. - Abstract: Hierarchical architectures consisting of two-dimensional (2D) nanostructures are of great interest for potential use in recent year. Here, we report the successful synthesis of four hierarchical tungsten oxide flower-like architectures via a simple yet facile hydrothermal method. The as-prepared WO 3 ·H 2 O hierarchical architectures are in fact assembled with numerous nanosheets or nanoplates. Through a comprehensive characterization of microstructures and morphologies of the as-prepared products, we find that petal thickness is a key factor for affecting gas-sensing performances. We further propose a possible growth mechanism for the four flower-like architectures. Moreover, gas-sensing measurements showed that the well-defined sheet-flower WO 3 ·H 2 O hierarchical architectures exhibited the excellent gas-sensing properties to ethanol owing to their largest amount of thin petal structures and pores

  9. Energy conservation. Concerted action between dwelling and occupant. Analysis of the module WoON 2012; Energiebesparing. Een samenspel van woning en bewoner. Analyse van de module Energie WoON 2012

    Energy Technology Data Exchange (ETDEWEB)

    Tigchelaar, C. [ECN Beleidsstudies, Petten (Netherlands); Leidelmeijer, K. [RIGO research en Advies, Amsterdam (Netherlands)

    2013-08-15

    Results are presented of the analysis on the WoON energy module, which they performed on behalf of the Dutch Ministry of the Interior and Kingdom Relations (BZK). Since 1995, BZK has been performing an elaborate study on the energy performance of the Dutch housing stock. This energy module is part of the WoON survey, which collects data on a wide range of topics related to housing and living. In 2012, this survey was carried out again. The data of 4,800 audits and questionnaires have been collected in a dataset that is linked to external data. The combined datasets offer unique and detailed insight in the fundamentals of energy consumption in dwellings. Due to the survey's long history, trends are now becoming visible in technical characteristics of dwellings as well as in behaviour. Among other things, the report describes trends in energy labels, energy measures, energy behaviour, energy consumption, living expenses, investments and saving potentials. Based on this information, general conclusions and policy recommendations are drawn [Dutch] Sinds 1995 wordt door het ministerie van BZK elke 5 tot 6 jaar een uitgebreid onderzoek naar de energetische kwaliteit van de Nederlandse woningvoorraad uitgevoerd als onderdeel van de kwalitatieve Woning Registratie (KWR) en later het Woon Onderzoek Nederland (WoON). Het ministerie heeft in 2012 veldwerk laten uitvoeren voor de module Energie 2012. De gegevens van 4.800 woningopnames en daaraan gekoppelde enquêtes zijn vastgelegd in een analysebestand en gekoppeld aan andere gegevensbronnen. De opname en de enquête samen geven een unieke, gedetailleerde inkijk in de achtergronden van het energiegebruik in woningen. Door de lange historie zijn trends in zowel technische eigenschappen van de woning als ook in gedrag goed zichtbaar. In deze publicatie geven ECN en RIGO een weergave van de analyses die zij in opdracht van het ministerie van BZK hebben uitgevoerd op de energiemodule. Hierbij komen alle facetten van het Wo

  10. Quantum dots as mediators in gas sensing: A case study of CdS sensitized WO{sub 3} sensing composites

    Energy Technology Data Exchange (ETDEWEB)

    Concina, Isabella, E-mail: concina@sensor.ing.unibs.it [CNR-INO SENSOR Laboratory, via Branze, 45, 25131 Brescia (Italy); SENSOR, Department of Information Engineering, Brescia University, via Valotti, 9, 25133 Brescia (Italy); Comini, Elisabetta [CNR-INO SENSOR Laboratory, via Branze, 45, 25131 Brescia (Italy); SENSOR, Department of Information Engineering, Brescia University, via Valotti, 9, 25133 Brescia (Italy); Kaciulis, Saulius [CNR-ISMN, Institute for the Study of Nanostructured Materials, Via dei Taurini, 19, 00185 Roma (Italy); Sberveglieri, Giorgio [CNR-INO SENSOR Laboratory, via Branze, 45, 25131 Brescia (Italy); SENSOR, Department of Information Engineering, Brescia University, via Valotti, 9, 25133 Brescia (Italy)

    2014-01-30

    In this study the proof of principle of the use of naked semiconductor directly generated on metal oxide surface as mediators in gas sensing is provided. Successive ionic layer absorption and reaction (SILAR) technique has been applied to sensitize a WO{sub 3} thin film with CdS quantum dots. Response to gases of bare WO{sub 3} is deeply modified: quantum dots dramatically increase the metal oxide conductance, otherwise rather poor, and modify the capability of detecting environmental pollutants, such as CO and NO{sub 2}. A modified sensing mechanism is proposed to rationalize the mediation exerted by the semiconducting active layer on the interaction between gaseous species and WO{sub 3} surface.

  11. Epitaxial growth of electron doped double perovskites La{sub x}A{sub 2-x}CrWO{sub 6} with A=Sr and Ca

    Energy Technology Data Exchange (ETDEWEB)

    Majewski, P. [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner Str. 8, 85748 Garching (Germany)]. E-mail: petra.majewski@wmi.badw.de; Gepraegs, S. [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner Str. 8, 85748 Garching (Germany); Boger, A. [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner Str. 8, 85748 Garching (Germany); Opel, M. [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner Str. 8, 85748 Garching (Germany); Alff, L. [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner Str. 8, 85748 Garching (Germany)]. E-mail: lambert.alff@wmi.badw.de; Gross, R. [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner Str. 8, 85748 Garching (Germany)

    2005-04-15

    Ferrimagnetic double perovskites are interesting for tunnel magnetoresistance (TMR) devices due to their high Curie-temperature and their half-metallicity. Because of the preferential formation of LaCrO{sub 3}, the synthesis of bulk samples of electron-doped La{sub x}Sr{sub 2-x}CrWO{sub 6} is difficult. However, due to the non-equilibrium growth conditions during pulsed laser deposition (PLD), the material can be grown as high-quality epitaxial film. We report the growth parameters of the compound La{sub x}Sr{sub 2-x}CrWO{sub 6} on SrTiO{sub 3} substrates. Using reflection high-energy electron diffraction (RHEED) a layer-by-layer growth over the whole film thickness has been observed. Ca{sub 2}CrWO{sub 6} grown on NdGaO{sub 3} has worse crystalline quality and shows paramagnetic behavior.

  12. Matrix Assisted and/or Laser Desorption Ionization Quadrupole Ion Trap Time-of-Flight Mass Spectrometry of WO3 Clusters Formation in Gas Phase. Nanodiamonds, Fullerene, and Graphene Oxide Matrices

    Science.gov (United States)

    Ausekar, Mayuri Vilas; Mawale, Ravi Madhukar; Pazdera, Pavel; Havel, Josef

    2018-01-01

    The formation of W x O y +●/-● clusters in the gas phase was studied by laser desorption ionization (LDI) and matrix assisted laser desorption ionization (MALDI) of solid WO3. LDI produced (WO3) n + ●/- ● (n = 1-7) clusters. In MALDI, when using nano-diamonds (NDs), graphene oxide (GO), or fullerene (C60) matrices, higher mass clusters were generated. In addition to (WO3) n -● clusters, oxygen-rich or -deficient species were found in both LDI and MALDI (with the total number of clusters exceeding one hundred ≈ 137). This is the first time that such matrices have been used for the generation of(WO3) n +●/-● clusters in the gas phase, while new high mass clusters (WO3) n -● (n = 12-19) were also detected. [Figure not available: see fulltext.

  13. Matrix Assisted and/or Laser Desorption Ionization Quadrupole Ion Trap Time-of-Flight Mass Spectrometry of WO3 Clusters Formation in Gas Phase. Nanodiamonds, Fullerene, and Graphene Oxide Matrices

    Science.gov (United States)

    Ausekar, Mayuri Vilas; Mawale, Ravi Madhukar; Pazdera, Pavel; Havel, Josef

    2018-03-01

    The formation of W x O y +●/-● clusters in the gas phase was studied by laser desorption ionization (LDI) and matrix assisted laser desorption ionization (MALDI) of solid WO3. LDI produced (WO3) n + ●/- ● ( n = 1-7) clusters. In MALDI, when using nano-diamonds (NDs), graphene oxide (GO), or fullerene (C60) matrices, higher mass clusters were generated. In addition to (WO3) n -● clusters, oxygen-rich or -deficient species were found in both LDI and MALDI (with the total number of clusters exceeding one hundred ≈ 137). This is the first time that such matrices have been used for the generation of(WO3) n + ●/-● clusters in the gas phase, while new high mass clusters (WO3) n -● ( n = 12-19) were also detected. [Figure not available: see fulltext.

  14. One-Step Formation of WO3-Loaded TiO2 Nanotubes Composite Film for High Photocatalytic Performance

    Directory of Open Access Journals (Sweden)

    Wai Hong Lee

    2015-04-01

    Full Text Available High aspect ratio of WO3-loaded TiO2 nanotube arrays have been successfully synthesized using the electrochemical anodization method in an ethylene glycol electrolyte containing 0.5 wt% ammonium fluoride in a range of applied voltage of 10–40 V for 30 min. The novelty of this research works in the one-step formation of WO3-loaded TiO2 nanotube arrays composite film by using tungsten as the cathode material instead of the conventionally used platinum electrode. As compared with platinum, tungsten metal has lower stability, forming dissolved ions (W6+ in the electrolyte. The W6+ ions then move towards the titanium foil and form a coherent deposit on titanium foil. By controlling the oxidation rate and chemical dissolution rate of TiO2 during the electrochemical anodization, the nanotubular structure of TiO2 film could be achieved. In the present study, nanotube arrays were characterized using FESEM, EDAX, XRD, as well as Raman spectroscopy. Based on the results obtained, nanotube arrays with average pore diameter of up to 74 nm and length of 1.6 µm were produced. EDAX confirmed the presence of tungsten element within the nanotube arrays which varied in content from 1.06 at% to 3.29 at%. The photocatalytic activity of the nanotube arrays was then investigated using methyl orange degradation under TUV 96W UV-B Germicidal light irradiation. The nanotube with the highest aspect ratio, geometric surface area factor and at% of tungsten exhibited the highest photocatalytic activity due to more photo-induced electron-hole pairs generated by the larger surface area and because WO3 improves charge separation, reduces charge carrier recombination and increases charge carrier lifetime via accumulation of electrons and holes in the two different metal oxide semiconductor components.

  15. RhoE is regulated by cyclic AMP and promotes fusion of human BeWo choriocarcinoma cells.

    Directory of Open Access Journals (Sweden)

    Gavin P Collett

    Full Text Available Fusion of placental villous cytotrophoblasts with the overlying syncytiotrophoblast is essential for the maintenance of successful pregnancy, and disturbances in this process have been implicated in pathological conditions such as pre-eclampsia and intra-uterine growth retardation. In this study we examined the role of the Rho GTPase family member RhoE in trophoblast differentiation and fusion using the BeWo choriocarcinoma cell line, a model of villous cytotrophoblast fusion. Treatment of BeWo cells with the cell permeable cyclic AMP analogue dibutyryl cyclic AMP (dbcAMP resulted in a strong upregulation of RhoE at 24 h, coinciding with the onset of fusion. Using the protein kinase A (PKA-specific cAMP analogue N(6-phenyl-cAMP, and a specific inhibitor of PKA (14-22 amide, PKI, we found that upregulation of RhoE by cAMP was mediated through activation of PKA signalling. Silencing of RhoE expression by RNA interference resulted in a significant decrease in dbcAMP-induced fusion. However, expression of differentiation markers human chorionic gonadotrophin and placental alkaline phosphatase was unaffected by RhoE silencing. Finally, we found that RhoE upregulation by dbcAMP was significantly reduced under hypoxic conditions in which cell fusion is impaired. These results show that induction of RhoE by cAMP is mediated through PKA and promotes BeWo cell fusion but has no effect on functional differentiation, supporting evidence that these two processes may be controlled by separate or diverging pathways.

  16. The Wolbachia WO bacteriophage proteome in the Aedes albopictus C/wStr1 cell line: evidence for lytic activity?

    Science.gov (United States)

    Baldridge, Gerald D; Markowski, Todd W; Witthuhn, Bruce A; Higgins, LeeAnn; Baldridge, Abigail S; Fallon, Ann M

    2016-01-01

    Wolbachia pipientis (Rickettsiales), an obligate intracellular alphaproteobacterium in insects, manipulates host reproduction to maximize invasion of uninfected insect populations. Modification of host population structure has potential applications for control of pest species, particularly if Wolbachia can be maintained, manipulated, and genetically engineered in vitro. Although Wolbachia maintains an obligate mutualism with genome stability in nematodes, arthropods can be co-infected with distinct Wolbachia strains, and horizontal gene transfer between strains is potentially mediated by WO phages encoded within Wolbachia genomes. Proteomic analysis of a robust, persistent infection of a mosquito cell line with wStr from the planthopper, Laodelphax striatellus, revealed expression of a full array of WO phage genes, as well as nine of ten non-phage genes that occur between two distinct clusters of WOMelB genes in the genome of wMel, which infects Drosophila melanogaster. These non-phage genes encode potential host-adaptive proteins and are expressed in wStr at higher levels than phage structural proteins. A subset of seven of the non-phage genes is flanked by highly conserved non-coding sequences, including a putative promoter element, that are not present in a syntenically arranged array of homologs in plasmids from three tick-associated Rickettsia spp. These studies expand our understanding of wStr in a host cell line derived from the mosquito, Aedes albopictus, and provide a basis for investigating conditions that favor the lytic phase of the WO phage life cycle and recovery of infectious phage particles.

  17. Caspase-8 activity is part of the BeWo trophoblast cell defense mechanisms against Trypanosoma cruzi infection.

    Science.gov (United States)

    Carrillo, Ileana; Droguett, Daniel; Castillo, Christian; Liempi, Ana; Muñoz, Lorena; Maya, Juan Diego; Galanti, Norbel; Kemmerling, Ulrike

    2016-09-01

    Congenital Chagas disease is caused by the protozoan parasite Trypanosoma cruzi that must cross the placental barrier during transmission. The trophoblast constitutes the first tissue in contact with the maternal-blood circulating parasite. Importantly, the congenital transmission rates are low, suggesting the presence of local placental defense mechanisms. Cellular proliferation and differentiation as well as apoptotic cell death are induced by the parasite and constitute part of the epithelial turnover of the trophoblast, which has been suggested to be part of those placental defenses. On the other hand, caspase-8 is an essential molecule in the modulation of trophoblast turnover by apoptosis and by epithelial differentiation. As an approach to study whether T. cruzi induced trophoblast turnover and infection is mediated by caspase-8, we infected BeWo cells (a trophoblastic cell line) with the parasite and determined in the infected cells the expression and enzymatic activity of caspase-8, DNA synthesis (as proliferation marker), β-human chorionic gonadotropin (β-hCG) (as differentiation marker) and activity of Caspase-3 (as apoptotic death marker). Parasite load in BeWo cells was measured by DNA quantification using qPCR and cell counting. Our results show that T. cruzi induces caspase-8 activity and that its inhibition increases trophoblast cells infection while decreases parasite induced cellular differentiation and apoptotic cell death, but not cellular proliferation. Thus, caspase-8 activity is part of the BeWo trophoblast cell defense mechanisms against T. cruzi infection. Together with our previous results, we suggest that the trophoblast turnover is part of local placental anti-parasite mechanisms. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Structural, optical and electrical properties of WO3-Ag nanocomposites for the electro-optical devices

    Science.gov (United States)

    Najafi-Ashtiani, Hamed; Bahari, Ali; Gholipour, Samira; Hoseinzadeh, Siamak

    2018-01-01

    The composites of tungsten trioxide and silver are synthesized by sodium tungstate and silver nitrate precursors. The structural properties of composite coatings are studied by FTIR, XRD, and XPS. The FTIR analysis of synthesized composite powder corroborated the bonds between tungsten and oxygen elements in WO3 molecules. Furthermore, the XRD spectra show crystalline nature while particle size analysis that is investigated by X-powder software shows average particle size of 24 and 25 nm for samples. The structural analyses show that the addition of silver dopant does not change the stoichiometry of tungsten trioxide and only increase the size of the aggregation in the films. Furthermore, these films have an average approximate roughness of about 10.7, 13.1 and 14.2 nm for sample 1, 2 and 3, respectively. The real and imaginative parts of permittivity are investigated using LCR meter in the frequency range 1 Hz-10 GHz. The optical spectra of composite coatings are characterized in the 300-900 nm wavelength range and the calculation of optical band gaps of them exhibited the directly allowed transition with the values of 3.8 and 3.85 eV. From UV-visible spectroscopy studies, the absorption coefficient of the composite thin films is determined to be of the order of 105 cm- 1 and the obtained refraction and extinction indexes indicated normal dispersive coatings. Due to their optical and electrical properties, the synthesized composite material is a promising candidate for use in electro-optical applicants.

  19. Breath acetone monitoring by portable Si:WO{sub 3} gas sensors

    Energy Technology Data Exchange (ETDEWEB)

    Righettoni, Marco; Tricoli, Antonio; Gass, Samuel [Particle Technology Laboratory, Department of Mechanical and Process Engineering ETH Zurich, CH-8092 Zurich (Switzerland); Schmid, Alex; Amann, Anton [Univ.-Clinic for Anesthesia, Innsbruck Medical University, A-6020 Innsbruck (Austria); Breath Research Institute of the Austrian Academy of Sciences, A-6850 Dornbirn (Austria); Pratsinis, Sotiris E., E-mail: sotiris.pratsinis@ptl.mavt.ethz.ch [Particle Technology Laboratory, Department of Mechanical and Process Engineering ETH Zurich, CH-8092 Zurich (Switzerland)

    2012-08-13

    Highlights: Black-Right-Pointing-Pointer Portable sensors were developed and tested for monitoring acetone in the human breath. Black-Right-Pointing-Pointer Acetone concentrations down to 20 ppb were measured with short response times (<30 s). Black-Right-Pointing-Pointer The present sensors were highly selective to acetone over ethanol and water. Black-Right-Pointing-Pointer Sensors were applied to human breath: good agreement with highly sensitive PTR-MS. Black-Right-Pointing-Pointer Tests with people at rest and during physical activity showed the sensor robustness. - Abstract: Breath analysis has the potential for early stage detection and monitoring of illnesses to drastically reduce the corresponding medical diagnostic costs and improve the quality of life of patients suffering from chronic illnesses. In particular, the detection of acetone in the human breath is promising for non-invasive diagnosis and painless monitoring of diabetes (no finger pricking). Here, a portable acetone sensor consisting of flame-deposited and in situ annealed, Si-doped epsilon-WO{sub 3} nanostructured films was developed. The chamber volume was miniaturized while reaction-limited and transport-limited gas flow rates were identified and sensing temperatures were optimized resulting in a low detection limit of acetone ({approx}20 ppb) with short response (10-15 s) and recovery times (35-70 s). Furthermore, the sensor signal (response) was robust against variations of the exhaled breath flow rate facilitating application of these sensors at realistic relative humidities (80-90%) as in the human breath. The acetone content in the breath of test persons was monitored continuously and compared to that of state-of-the-art proton transfer reaction mass spectrometry (PTR-MS). Such portable devices can accurately track breath acetone concentration to become an alternative to more elaborate breath analysis techniques.

  20. Discovery of a [WO] central star in the planetary nebula Th 2-A

    Science.gov (United States)

    Weidmann, W. A.; Gamen, R.; Díaz, R. J.; Niemela, V. S.

    2008-09-01

    Context: About 2500 planetary nebulae are known in our Galaxy but only 224 have central stars with reported spectral types in the Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (Acker et al. 1992; Acker et al. 1996). Aims: We have started an observational program aiming to increase the number of PN central stars with spectral classification. Methods: By means of spectroscopy and high resolution imaging, we identify the position and true nature of the central star. We carried out low resolution spectroscopic observations at CASLEO telescope, complemented with medium resolution spectroscopy performed at Gemini South and Magellan telescopes. Results: As a first outcome of this survey, we present for the first time the spectra of the central star of the PN Th 2-A. These spectra show emission lines of ionized C and O, typical in Wolf-Rayet stars. Conclusions: We identify the position of that central star, which is not the brightest one of the visual central pair. We classify it as of type [WO 3]pec, which is consistent with the high excitation and dynamical age of the nebula. Based on data collected at (i) the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina y Universidades Nacionales de La Plata, Córdoba y San Juan, Argentina; (ii) the 6.5 m Magellan Telescopes at Las Campanas Observatory, Chile; (iii) the 8 m Gemini South Telescope, Chile.

  1. Ferromagnetism and half metallicity induced by oxygen vacancies in the double perovskite BaSrNiWO{sub 6}: DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Aharbil, Y. [Laboratoire de Chimie Physique des Matériaux LCPM, Faculté des Sciences Ben M' Sik, Casablanca (Morocco); Labrim, H. [Unité Science de la Matière/DERS/Centre National de l’Energie, des Sciences et des Techniques Nucléaires (CNESTEN), Rabat (Morocco); Benmokhtar, S.; Haddouch, M. Ait [Laboratoire de Chimie Physique des Matériaux LCPM, Faculté des Sciences Ben M' Sik, Casablanca (Morocco); Bahmad, L., E-mail: bahmad@fsr.ac.ma [Mohammed V University in Rabat, Laboratoire de Magnétisme et Physique des Hautes Energies L.M.P.H.E. URAC-12, B.P. 1014, Rabat (Morocco); Belhaj, A. [LIRST, Département de Physique, Faculté Poly-disciplinaire, Université Sultan Moulay Slimane, Béni Mellal (Morocco); Ez-Zahraouy, H.; Benyoussef, A. [Mohammed V University in Rabat, Laboratoire de Magnétisme et Physique des Hautes Energies L.M.P.H.E. URAC-12, B.P. 1014, Rabat (Morocco)

    2016-11-01

    Using the spin polarized density functional theory (DFT) and exploring the Plane-Wave Self-Consistent Field (PWscf) code implemented in Quantum-ESPRESSO package, we investigate the effect of the Oxygen vacancies (V{sub O}) and the Oxygen interstitial (O{sub i}) on the double perovskite BaSrNiWO{sub 6}. This deals with the magnetic ordering and the electronic structure in such a pure sample exhibiting the insulating anti-ferromagnetic (AFM) state. This study shows that the presence of oxygen deficient defects converts the insulating to half metal with ferromagnetic or anti-ferromagnetic states. The magnetic ordering in BaSrNiWO{sub 6−δ} depends on the position of the Oxygen vacancy in the unit cell. However, it has been shown that the Oxygen interstitial preserves the anti-ferromagnetic propriety. We have computed the formation energies of different positions of the Oxygen vacancy (V{sub O}) and the Oxygen interstitial (O{sub i}) in the BaSrNiWO{sub 6} compound. We showed that the formation of V{sub O} is easier and vice versa for the O{sub i} formation. The obtained results reveal(V{sub O}) and the Oxygen interstitial (O{sub i}) that the anti-ferromagnetic can be converted to ferromagnetic in the double perovskite BaSrNiWO{sub 6} induced by Oxygen vacancies V{sub O}. - Highlights: • We have studied the ferromagnetism and Half Metallicity in Double Perovskite BaSrNiWO{sub 6}. • We have applied the Ab-inito calculations using the DFT approach. • We showed the effects induced by Oxygen Vacancies and Oxygen interstitial. • We found that the magnetic ordering in BaSrNiWO{sub 6−δ} depends on the position of the Oxygen vacancy in the unit cell.

  2. Surface oxygen vacancy induced solar light activity enhancement of a CdWO4/Bi2O2CO3core-shell heterostructure photocatalyst.

    Science.gov (United States)

    Yang, Chunming; Gao, Guimei; Zhang, Junjun; Liu, Ruiping; Fan, Ruicheng; Zhao, Ming; Wang, Yongwang; Gan, Shucai

    2017-06-07

    A CdWO 4 /Bi 2 O 2 CO 3 core-shell heterostructure photocatalyst was fabricated via a facile two-step hydrothermal process. Flower-like Bi 2 O 2 CO 3 was synthesized and functioned as the cores on which CdWO 4 nanorods were coated as the shells. Photoluminescence (PL) spectra and electron paramagnetic resonance (EPR) demonstrate that the CdWO 4 /Bi 2 O 2 CO 3 core-shell heterostructure photocatalyst possesses a large amount of oxygen vacancies, which induce defect levels in the band gap and help to broaden light absorption. The photocatalyst exhibits enhanced photocatalytic activity for Rhodamine B (RhB), methylene blue (MB), methyl orange (MO), and colorless contaminant phenol degradation under solar light irradiation. The heterostructured CdWO 4 /Bi 2 O 2 CO 3 core-shell photocatalyst shows drastically enhanced photocatalytic properties compared to the pure CdWO 4 and Bi 2 O 2 CO 3 . This remarkable enhancement is attributed to the following three factors: (1) the presence of oxygen vacancies induces defect levels in the band gap and increases the visible light absorption; (2) intimate interfacial interactions derived from the core-shell heterostructure; and (3) the formation of the n-n junction between the CdWO 4 and Bi 2 O 2 CO 3 . The mechanism is further explored by analyzing its heterostructure and determining the role of active radicals. The construction of high-performance photocatalysts with oxygen vacancies and core-shell heterostructures has great potential for degradation of refractory contaminants in water with solar light irradiation.

  3. Synthesis of novel and stable g-C3N4-Bi2WO6 hybrid nanocomposites and their enhanced photocatalytic activity under visible light irradiation.

    Science.gov (United States)

    Li, Haitao; Li, Na; Wang, Ming; Zhao, Beiping; Long, Fei

    2018-03-01

    Graphitic carbon nitride (g-C 3 N 4 ) nanosheets with a thickness of only a few nanometres were obtained by a facile deammoniation treatment of bulk g-C 3 N 4 and were further hybridized with Bi 2 WO 6 nanoparticles on the surface via a solvothermal method. The composite photocatalysts were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis diffuse reflection spectroscopy and X-ray photoelectron spectroscopy (XPS). The HR-TEM results show that the nano-sized Bi 2 WO 6 particles were finely distributed on g-C 3 N 4 sheet surface, which forms heterojunction structure. The UV-vis diffuse reflectance spectra (DRS) show that the absorption edge of composite photocatalysts shifts towards lower energy region in comparison with those of pure g-C 3 N 4 and Bi 2 WO 6 . The degradation of methyl orange (MO) tests reveals that the optimum activity of 8 : 2 g-C 3 N 4 -Bi 2 WO 6 photocatalyst is almost 2.7 and 8.5 times higher than those of individual g-C 3 N 4 and Bi 2 WO 6 . Moreover, the recycle experiments depict high stability of the composite photocatalysts. Through the study of the influencing factors, a possible photocatalytic mechanism is proposed. The enhancement in both photocatalytic performance and stability was caused by the synergistic effect, including the effective separation of the photogenerated electron-hole pairs at the interface of g-C 3 N 4 and Bi 2 WO 6 , the smaller the particle size and the relatively larger specific surface area of the composite photocatalyst.

  4. Synergy of adsorption and visible-light photocatalytic degradation of methylene blue by a bifunctional Z-scheme heterojunction of WO3/g-C3N4

    Science.gov (United States)

    Liu, Xin; Jin, Ailing; Jia, Yushuai; Xia, Tonglin; Deng, Chenxin; Zhu, Meihua; Chen, Changfeng; Chen, Xiangshu

    2017-05-01

    A novel bifunctional Z-scheme heterojunction possessing high adsorption and photocatalytic activity, WO3/g-C3N4 with well-defined morphology has been successfully synthesized by in-situ liquid phase process and characterized by various analytical techniques. The degradation experiments demonstrate that the Z-scheme photocatalyst shows a synergistic effect between adsorption and photocatalysis for the removal of methylene blue (MB) under visible-light irradiation, with the optimum adsorption and photocatalytic activity both found at 30 wt% WO3/g-C3N4. Under illumination, the photodegradation performance of 30 wt% WO3/g-C3N4 is improved to 2.5 and 2.7 times that of pure g-C3N4 and pure WO3, respectively. The possible mechanism for the photocatalytic activity enhancement could be attributed to the formation of a Z-scheme heterojunction system based on the active species trapping experiments. Furthermore, the investigations of adsorption kinetics and isotherm show that the adsorption process can be well described by pseudo-second-order kinetic model, and the adsorption capacity of 30 wt% WO3/g-C3N4 is enhanced to 4 times that of pure WO3, with a maximum of 97.00 mg g-1 determined by Langmuir isotherm. As evidenced by N2 physisorption, zeta potential and time-resolved photoluminescence measurements, the significant enhancement of the integrated adsorption and photocatalytic degradation efficiency is mainly due to the synergistic advantages of large surface area, negative zeta potential and facilitated charge separation of the composite.

  5. One-dimensional Z-scheme TiO{sub 2}/WO{sub 3}/Pt heterostructures for enhanced hydrogen generation

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Hongqing [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); State Centre for International Cooperation on Designer Low-carbon and Environmental Materials (SCICDLCEM), Zhengzhou University, Zhengzhou 450001, Henan (China); Zhang, Peng, E-mail: Zhangp@zzu.edu.cn [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); State Centre for International Cooperation on Designer Low-carbon and Environmental Materials (SCICDLCEM), Zhengzhou University, Zhengzhou 450001, Henan (China); Hu, Junhua, E-mail: Hujh@zzu.edu.cn [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); State Centre for International Cooperation on Designer Low-carbon and Environmental Materials (SCICDLCEM), Zhengzhou University, Zhengzhou 450001, Henan (China); Pan, Jimin [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Fan, Jiajie [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); State Centre for International Cooperation on Designer Low-carbon and Environmental Materials (SCICDLCEM), Zhengzhou University, Zhengzhou 450001, Henan (China); Shao, Guosheng [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); State Centre for International Cooperation on Designer Low-carbon and Environmental Materials (SCICDLCEM), Zhengzhou University, Zhengzhou 450001, Henan (China); Institute for Renewable Energy and Environmental Technologies, University of Bolton, Bolton BL35AB (United Kingdom)

    2017-01-01

    Graphical abstract: We reported one-dimensional solid-state Z-scheme photosynthetic heterojunction system with Pt nanoparticle as an electron collector and WO{sub 3} as a hole collector, leading to effective charge separation. - Highlights: • The composite nanofibers were fabricated by facile electrospinning technique. • The composite nanofibers exhibited enhanced activity for H{sub 2} evolution. • Enhanced activity is due to the formation of Z-scheme TiO{sub 2}/WO{sub 3}/Pt heterojunction. - Abstract: One-dimensional Z-scheme TiO{sub 2}/WO{sub 3}/Pt heterostructures were fabricated by integrating a facile electrospinning technique and subsequent annealing in air. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and UV–vis diffuse reflectance spectroscopy, were used to characterize the as-fabricated samples. The results showed that the H{sub 2}-generation of the as-fabricated one-dimensional Z-scheme TiO{sub 2}/WO{sub 3}/Pt heterostructures (S2) was greatly enhanced compared with pure TiO{sub 2} nanofibers (S0) and TiO{sub 2}/WO{sub 3} nanofibers (S1). The enhanced photocatalyst activities were mainly attributed to the solid-state Z-scheme photosynthetic heterojunction system with Pt nanoparticle as an electron collector and WO{sub 3} as a hole collector, leading to effective charge separation on these semiconductors, which were evidenced by electrochemical impedance spectroscopy (EIS) and photocurrent analysis.

  6. Die samehangende verskeidenheid van mens­like vryheid veral in samelewingsverband (wo. Universitêre en akademiese vryheid

    Directory of Open Access Journals (Sweden)

    H. G. Stoker

    1964-03-01

    Full Text Available Ons tref menslike vryheid (en verslaafdheid as positiewe idion (verskynsel by sy handelinge aan. (Ons verstaan „handeling” in ruime sin en sluit o.a. aktes, wo. bv. dink, liefhê, waardeer en kies daarby in. Menslike vryheid' is as handeling (i roepingsvervullende antwoor- ding (ii op die aan die mens geskenkte (en hom verplig- tende moontlikheid van keuse (iii in onderworpenheid (resp. gehoorsaamheid aan die betrokke behorenseise w aaronder die mens ás méns staan.

  7. Synthesis and characterization of monoclinic KGd(WO4)2 particles for non-cubic transparent ceramics

    Science.gov (United States)

    Thangaraju, D.; Durairajan, A.; Balaji, D.; Moorthy Babu, S.

    2013-02-01

    Monoclinic KGd(WO4)2 (KGW) particles were synthesized using polymeric metal complex sol-gel synthesis method. The derived particles were made as colloidal suspension form for better rotation of particles to have optimum response for applied magnetic field. The KGW fine particle suspension was prepared using electrostatic repulsion by electrolyte polymer. Prepared suspension was kept at 2 T and particles were settled using electrophoretic sedimentation using pH adjustment. The derived sediment was dried at 100 °C and the properties were characterized using XRD.

  8. Investigation of the optical properties of KGd(WO4)2:Nd3+ crystals with allowance for absorption

    Science.gov (United States)

    Konstantinova, A. F.; Filippov, V. V.; Palto, S. P.; Evdishchenko, E. A.; Imangazieva, K. B.; Orekhova, V. P.

    2007-11-01

    The optical properties of a biaxial absorbing KGd(WO4)2:Nd3+ crystal have been investigated. The main refractive indices were measured in the visible spectral range and the absorption and transmission spectra of samples of these crystals were studied. The changes in the refractive indices were in the region of the absorption bands with the use of the Kramers-Kronig relation. Conoscopic pictures of this crystal in the regions of transparency and absorption bands were calculated and are presented.

  9. Modification of the performance of WO3-ZrO2 catalysts by metal addition in hydrocarbon reactions

    International Nuclear Information System (INIS)

    Torres, Gerardo Carlos; Manuale, Debora Laura; Benitez, Viviana Monica; Vera, Carlos Roman; Yori, Juan Carlos

    2012-01-01

    A study of the different hydrocarbon reactions over Ni doped WO 3 -ZrO 2 catalysts was performed. Ni was found as NiO at low Ni concentration while at high Ni concentrations a small fraction was present as a metal. For both cases, Ni strongly modified total acidity and concentration of strong acid sites. In the cyclohexane dehydrogenation reaction, Ni addition promotes both benzene and methyl cyclopentane production. The hydroconversion activity (n-butane and n-octane) increases with the augment of total acidity produced by Ni. The selectivity to reaction products is modified according to the acid strength distribution changes produced by Ni addition. (author)

  10. Growth of two-dimensional KGd(WO 4) 2 nanorods by modified sol-gel Pechini method

    Science.gov (United States)

    Thangaraju, D.; Samuel, P.; Moorthy Babu, S.

    2010-08-01

    KGd (WO 4) 2 nanocrystalline powder was obtained by modified sol-gel Pechini method. The synthesis procedure was optimized with TGA and DTA analyses. Synthesized polymeric resin was calcinated at 550 and 700 °C using resistive furnace in an open atmosphere. Crystallinity of annealed powder was confirmed using X-ray diffraction. Absorption peaks of FT-IR for gel and the annealed samples, at two different temperatures show the decomposition of citrate-ethylene glycol complex and formation of KGW particles. Raman analysis confirms that the derived particles have well constructed bridges of W-O-O-W. External morphology of the particles was analysed through SEM.

  11. Gamma ray shielding and structural properties of PbO-P2O5-Na2WO4 glass system

    Science.gov (United States)

    Dogra, Mridula; Singh, K. J.; Kaur, Kulwinder; Anand, Vikas; Kaur, Parminder

    2017-05-01

    The present work has been undertaken to study the gamma ray shielding properties of PbO-P2O5-Na2WO4 glass system. The values of mass attenuation coefficient and half value layer parameter at photon energies 511, 662 and 1173 KeV have been determined using XCOM computer software developed by National Institute of Standards and Technology. The density, molar volume, XRD, UV-VIS and Raman studies have been performed to study the structural properties of the prepared glass system to check the possibility of the use of prepared samples as an alternate to conventional concrete for gamma ray shielding applications.

  12. Modification of the performance of WO3-ZrO2 catalysts by metal addition in hydrocarbon reactions

    Directory of Open Access Journals (Sweden)

    Gerardo Carlos Torres

    2012-01-01

    Full Text Available A study of the different hydrocarbon reactions over Ni doped WO3-ZrO2 catalysts was performed. Ni was found as NiO at low Ni concentration while at high Ni concentrations a small fraction was present as a metal. For both cases, Ni strongly modified total acidity and concentration of strong acid sites. In the cyclohexane dehydrogenation reaction, Ni addition promotes both benzene and methyl cyclopentane production. The hydroconversion activity (n-butane and n-octane increases with the augment of total acidity produced by Ni. The selectivity to reaction products is modified according to the acid strength distribution changes produced by Ni addition.

  13. PERAN DAN POTENSI KYAI PESANTREN DALAM PENGEMBANGAN LEMBAGA KEUANGAN SYARIAH DI PEKALONGAN Tinjauan WoM Marketing dan Buzz Marketing

    Directory of Open Access Journals (Sweden)

    AM. M. Hafidz MS

    2015-01-01

    Full Text Available Because of their strenght, charisma, knowledge, authority in the boarding school, leverage influentality, expertise, and leverage social networks, Kyai Pesantren have the potential to market the Islamic Financial Institutions by creating buzz and WoM marketing. Their role as marketer could be (1 providing education and learning on Islamic economics, Syaria Islamic Institution and fiqh muamalah (2 building several business units to teach their students operationally and practically on Islamic economics (3 posing as Syaria Supervisory Board in existing Syaria Islamic Institution as Syaria compliance guardian (4 disseminating on Syaria Islamic Institution role to community when giving them a lecture.

  14. Improved limits for natural {alpha} radioactivity of tungsten with a CaWO{sub 4} scintillating bolometer

    Energy Technology Data Exchange (ETDEWEB)

    Cebrian, S.; Coron, N.; Dambier, G.; Marcillac, P. de; Garcia, E.; Irastorza, I.G.; Leblanc, J.; Morales, A.; Morales, J.; Ortiz de Solorzano, A.; Puimedon, J.; Sarsa, M.L.; Villar, J.A

    2003-03-13

    An experiment has been carried out at the Canfranc Underground Laboratory with a 54 g CaWO{sub 4} scintillating bolometer in the frame of the ROSEBUD (Rare Objects SEarch with Bolometers UndergrounD) Collaboration. This detector has been developed in order to achieve a good particle discrimination capability by means of the simultaneous detection of light and heat with the goal of rejecting background in dark matter search. This Letter reports, as a byproduct of such development, improved limits on the lifetime for {alpha} decaying tungsten isotopes.

  15. The investigation of a model of an EM calorimeter on NaBi(WO4)2 crystals

    International Nuclear Information System (INIS)

    Kalinin, B.N.

    1995-01-01

    We have constructed a mock-up model consisting of nine elements to evaluate the space and energy resolution of the NaBi(WO 4 ) 2 crystal electromagnetic calorimeter. The characteristics of the mock-up model have been studied with a 700 MeV electron beam. It is shown that with cell dimensions of about 2.4 cm one can achieve an accuracy of < 4 mm in measuring the coordinates. The investigations have shown that the calorimeter has fast operation, satisfactory energy resolution and good space resolution characteristics. (orig.)

  16. Behavior of the monophosphate tungsten bronzes (PO2)4(WO3)2m (m = 7 and 8) in the course of electrochemical lithium insertion

    International Nuclear Information System (INIS)

    Martinez-de la Cruz, A.; Longoria Rodriguez, F.E.; Gonzalez, Lucy T.; Torres-Martinez, Leticia M.

    2007-01-01

    The electrochemical lithium insertion process has been studied in the family of monophosphate tungsten bronzes (PO 2 ) 4 (WO 3 ) 2m , where m = 7 and 8. Structural changes in the pristine oxides were followed as lithium insertion proceeded. Through potentiostatic intermittent technique the different processes which take place in the cathode during the discharge of the cell were analyzed. The nature of the bronzes Li x (PO 2 ) 4 (WO 3 ) 2m formed was determined by in situ X-ray diffraction experiments. These results have allowed establishing a correlation with the reversible/irreversible processes detected during the electrochemical lithium insertion

  17. Prospects for a precision timing upgrade of the CMS PbWO$_{4}$ crystal electromagnetic calorimeter for the HL-LHC

    CERN Document Server

    Marzocchi, Badder

    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 on the timing properties of PbWO crystals, as well as the impact of the photosensors and the readout electronics on the timing performance, will be presented. Test beam studies on the timing performance of PbWO$_{4}$ crystals with various photosensors and readout electronics will be shown.

  18. In situ controllable synthesis of novel surface plasmon resonance-enhanced Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} composite for enhanced and stable visible light photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Jiali [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Dai, Kai, E-mail: daikai940@chnu.edu.cn [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Zhang, Jinfeng [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Lu, Luhua, E-mail: lhlu@cug.edu.cn [Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China); Liang, Changhao, E-mail: chliang@issp.ac.cn [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Key Laboratory of Materials Physics and Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 23003 (China); Geng, Lei; Wang, Zhongliao; Yuan, Guangyu; Zhu, Guangping [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China)

    2017-01-01

    Highlights: • Novel Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} ternary photocatalyst was prepared. • Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} showed enhanced catalytic activity. • Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} showed long reusable life. - Abstract: A novel hierarchical Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} ternary visible-light-driven photocatalyst was successfully synthesized by in situ doping Ag{sub 2}WO{sub 4} with Bi{sub 2}MoO{sub 6} nanosheets through a facile hydrothermal and photochemical process. The morphology, structure, optical performance and crystallinity of the products were measured by field emission scanning electron microscope (FESEM), energy dispersive spectrometer (EDS), UV–vis diffuse reflectance spectroscopy (DRS) and X-ray diffraction (XRD). The results showed that Ag{sub 2}WO{sub 4}/Ag was uniformly dispersed on the surface of Bi{sub 2}MoO{sub 6} nanosheets. The photocatalytic performance of Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} heterostructures was evaluated by the degradation of methylene blue (MB) under 410 nm LED arrays. The ternary Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} nanocomposite exhibits higher photocatalytic activity than Bi{sub 2}MoO{sub 6} and Ag{sub 2}WO{sub 4}. The synergistic effect of Ag{sub 2}WO{sub 4} and Bi{sub 2}MoO{sub 6} could generated more heterojunctions which promoted photoelectrons transfer from Ag{sub 2}WO{sub 4} to Bi{sub 2}MoO{sub 6}, leading to the improvement of photocatalytic performance by photoelectrons-holes recombination suppression. At the same time, the surface plasmon resonance of Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} is another crucial reason for the high photocatalytic performance of organic pollutants degradation. And the 20 wt% Ag{sub 2}WO{sub 4}-loaded Bi{sub 2}MoO{sub 6} shows the optimal photocatalytic performance in the degradation of MB. In addition, the ternary composites can be easily reclaimed by precipitation and exhibits high stability of photocatalytic

  19. Fabrication and photocatalytic activity enhanced mechanism of direct Z-scheme g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4} photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Bicheng [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Department of Science and Environmental Studies The Hong Kong Institute of Education, Tai Po, N.T., Hong Kong (China); Xia, Pengfei; Li, Yao [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Ho, Wingkei, E-mail: keithho@ied.edu.hk [Department of Science and Environmental Studies The Hong Kong Institute of Education, Tai Po, N.T., Hong Kong (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2017-01-01

    Highlights: • g-C{sub 3}N{sub 4} acted as a support for the in situ growth of β-Ag{sub 2}WO{sub 4}. • g-C{sub 3}N{sub 4} nanosheets inhibited the phase transformation of β-Ag{sub 2}WO{sub 4} to α-Ag{sub 2}WO{sub 4}. • g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4} exhibited a superior photocatalytic activity. • A direct Z-scheme photocatalytic mechanism could explain activity enhancement. - Abstract: Herein, a direct Z-scheme graphitic carbon nitride (g-C{sub 3}N{sub 4})/silver tungstate (Ag{sub 2}WO{sub 4}) photocatalyst was prepared by a facile in situ precipitation method using g-C{sub 3}N{sub 4} as a support and silver nitrate as a precursor. X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and elemental mapping demonstrated that β-Ag{sub 2}WO{sub 4} nanoparticles were evenly distributed on the surface of g-C{sub 3}N{sub 4} nanosheets, which acted as a support for the nucleation and growth of β-Ag{sub 2}WO{sub 4} and inhibited the phase transformation of metastable β-Ag{sub 2}WO{sub 4} to stable α-Ag{sub 2}WO{sub 4}. Photocatalytic experiments indicated that the g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4} nanocomposite photocatalyst displayed a better photocatalytic activity than pure g-C{sub 3}N{sub 4} and Ag{sub 2}WO{sub 4} toward the degradation of methyl orange. The enhanced photocatalytic performance of g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4} could be well explained by a direct Z-scheme photocatalytic mechanism. This mechanism was related to the efficient space separation of photogenerated electron–hole pairs and the great oxidation and reduction capabilities of the g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4} system. This work provided new insights into the design and fabrication of g-C{sub 3}N{sub 4}-based direct Z-scheme photocatalysts.

  20. The social nature of environmental knowledge among the nomadic WoÉ - aaÉ"e of Niger

    Directory of Open Access Journals (Sweden)

    Nikolaus Schareika

    2014-12-01

    Full Text Available Pastoral nomads such as West Africa's WoÉ - aaÉ"e are renowned for the impressive environmental knowledge they apply to successfully raise animal herds in arid and variable environments. We looked at such herders' knowledge not as based on individual learning and expertise but as ultimately social in the sense that it is formed, made available, and linked to pastoral decision making in the public and interactive space of permanent talking, discussing, and negotiating among peers. Drawing on theoretical ideas from science and technology studies, a number of concrete social situations of information management and pastoral decision making were explored in detail to reveal the distinctly social character of WoÉ - aaÉ"e knowledge. Special emphasis has been given to the institutional framework of knowledge exchange; the blending of moral values and empirical facts in particular statements of knowledge; the dialogic and collaborative nature of information procurement and assessment; and the contingency of decisions reached after lengthy rounds of discussion among herders.

  1. Synthesis and characterization of nanocrystalline ZnWO4-ZnO composites and their humidity sensing performance

    Directory of Open Access Journals (Sweden)

    M.V. Arularasu

    2016-12-01

    Full Text Available We investigate the experimental results on the composites ZnWO4-ZnO for electrical and humidity sensing properties are described. ZnWO4 (ZW prepared by precipitation method and this prepared zinc tungstate mixed with ZnO (ZO in different mole rations (100:0, 80:20, 60:40, 40:60, 20:80, 0:100. The products were characterized in detail by multi techniques: X-ray diffraction (XRD, energy dispersive X-ray analysis (EDX, field emission scanning electron microscopy (FE-SEM, transmission electron microscopy (TEM, Brunauer-Emmett-Teller (BET analysis and vibrating sample magnetometer (VSM. The composites were sintered in the form of the disc and subjected to dc resistance measurements. The dc resistance of these composites decreased on exposure to humidity at room temperature. These results demonstrate composite ZWZO-46 has the highest humidity sensitivity Sf = 3416, with a response and recovery time of 50 s and 100 s respectively. Keywords: Composites, Relative humidity, Humidity sensor, VSM, Hysteresis

  2. The effect of strain rate and temperature on the tensile behaviour of uranium 2 w/o molybdenum

    International Nuclear Information System (INIS)

    Harding, J.; Boyd, G.A.C.

    1983-01-01

    This report describes the uniaxial tensile behaviour of uranium 2 w/o molybdenum alloy over a wide range of temperature and strain rate. Specimen blanks taken from co-reduced and extruded U 2 w/o Mo rods were given one of two heat treatments. Longitudinal tensile test pieces, taken from these blanks at near surface locations were tested in the temperature range -150 deg C to +100 deg C at strain rates from quasistatic (10 -4 s -1 ) to 10 3 s -1 . To achieve this range of testing rates three machines were required: an Instron screw driven machine for rates up to 0.1 s -1 , a second specially constructed hydraulic machine for the range 0.1 s -1 to 50 s -1 and a drop weight machine for the highest strain rates. The ways in which the mechanical properties - elongation to fracture, flow stresses and ultimate tensile stress - vary with both temperature and strain rate are presented and discussed for material in both heat treatment conditions. (author)

  3. Effects of external phase on D-cycloserine loaded W/O nanocapsules prepared by the interfacial polymerization method.

    Science.gov (United States)

    Musumeci, Teresa; Ventura, Cinzia A; Carbone, Claudia; Pignatello, Rosario; Puglisi, Giovanni

    2011-07-01

    Water in oil (W/O) polybutylcyanoacrylate nanocapsules containing D-cycloserine (D-CS) for intranasal delivery were prepared by the interfacial polymerization method. Different oils, as external phase, for the preparation of the initial W/O miniemulsions were used and their effect on mean size and other physico-chemical properties were evaluated by photon correlation spectroscopy (PCS) and scanning electron microscopy (SEM) analysis. Two probes at different hydrophilicity were used to verify the internal aqueous nature of the core. Both miniemulsions and nanocapsules mean size and polydispersity index were influenced by the used external phase. Different entrapment efficiency were obtained for D-cycloserine-loaded nanocapsules correlated to the used oil [ranging from 39 to 51% encapsulation efficiency (E.E.)]. In vitro drug release showed an initial burst effect (ranging from 20 to 40%) followed by a slow release of D-CS for all preparations. This study demonstrated that many relevant physico-chemical and technological properties of polybutylcyanoacrylate nanocapsules prepared by interfacial polymerization of miniemulsions are significantly influenced by the external oil phase used. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  4. Characterization of nanoparticles of lidocaine in w/o microemulsions using small-angle neutron scattering and dynamic light scattering

    International Nuclear Information System (INIS)

    Shukla, A.; Kiselev, M.A.; Hoell, A.; Neubert, R.H.H.

    2004-01-01

    Microemulsions (MEs) are of special interest because a variety of reactants can be introduced into the nanometer-sized aqueous domains, leading to materials with controlled size and shape. In the past few years, significant research has been conducted in the reverse ME-mediated synthesis of organic nanoparticles. In this study, a w/o ME medium was employed for the synthesis of lidocaine by direct precipitation in w/o microemulsion systems: water/isopropylpalmitat/Tween80/Span80. The particle size as well as the location of nanoparticles in the ME droplet were characterized by means of dynamic light scattering (DLS) and small angle neutron scattering (SANS). It is observed that lidocaine precipitated in the aqueous cores because of its insolubility in water. Hydrodynamic radius and gyration radius of microemulsion droplets were estimated as ∼15 nm and ∼4.50 nm from DLS and SANS respectively. Furthermore, different size parameters obtained by DLS and SANS experiments were compared. (author)

  5. Cold sprayed WO3 and TiO2 electrodes for photoelectrochemical water and methanol oxidation in renewable energy applications.

    Science.gov (United States)

    Haisch, Christoph; Schneider, Jenny; Fleisch, Manuel; Gutzmann, Henning; Klassen, Thomas; Bahnemann, Detlef W

    2017-10-03

    Films prepared by cold spray have potential applications as photoanodes in electrochemical water splitting and waste water purification. In the present study cold sprayed photoelectrodes produced with WO 3 (active under visible light illumination) and TiO 2 (active under UV illumination) on titanium metal substrates were investigated as photoanodes for the oxidation of water and methanol, respectively. Methanol was chosen as organic model pollutant in acidic electrolytes. Main advantages of the cold sprayed photoelectrodes are the improved metal-semiconductor junctions and the superior mechanical stability. Additionally, the cold spray method can be utilized as a large-scale electrode fabrication technique for photoelectrochemical applications. Incident photon to current efficiencies reveal that cold sprayed TiO 2 /WO 3 photoanodes exhibit the best photoelectrochemical properties with regard to the water and methanol oxidation reactions in comparison with the benchmark photocatalyst Aeroxide TiO 2 P25 due to more efficient harvesting of the total solar light irradiation related to their smaller band gap energies.

  6. Thickness control in electrophoretic deposition of WO{sub 3} nanofiber thin films for solar water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Yuanxing; Lee, Wei Cheat; Canciani, Giacomo E.; Draper, Thomas C.; Al-Bawi, Zainab F. [Department of Chemistry, School of Life Sciences, University of Sussex, Brighton BN1 9QJ (United Kingdom); Bedi, Jasbir S. [School of Public Health & Zoonoses, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana 141004 Punjab (India); Perry, Christopher C. [Division of Biochemistry, School of Medicine, Loma Linda University, Loma Linda, CA 92350 (United States); Chen, Qiao, E-mail: qiao.chen@sussex.ac.uk [Department of Chemistry, School of Life Sciences, University of Sussex, Brighton BN1 9QJ (United Kingdom)

    2015-12-15

    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{sub 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{sub 3} nanofibers that EPD deposited on a substrate was achieved at a film thickness of 18 μm.

  7. Efficient Nd:KGd(WO4)2laser at 1.538-μm wavelength

    Science.gov (United States)

    Raevsky, Eugene V.; Gulin, Alexander V.; Ustimenko, Nikolai S.; Pavlovitch, Vladimir L.

    2000-04-01

    The radiation at around 1.5 micrometers has been extensively investigated over the last few years for eye-safe applications. This paper describes the development and performance of a pulsed solid-state laser based on nonlinear frequency conversion of the Nd:KGd(WO4)2 fundamental radiation into the near-infrared region of the spectrum. Neodymium-doped potassium gadolinium tungstate Nd:KGd(WO4)2 (Nd:KGW) possesses a combination of spectral and lasing characteristics uniquely favorable for laser operation. The explanation for the high efficiency which can be achieved with this material follows from high effective stimulated-emission cross section of laser transition. Also, in contrast to Nd:YAG, Nd:KGW is an efficient Raman medium. In the present paper most attention has been concentrated on the self-conversion of the laser wavelength at 1.351 micrometers to the first Stokes line at 1.538 micrometers . In conclusion, we have demonstrated a compact low-threshold source for the near-IR in a configuration of an intra-cavity solid-state Raman laser based on a flashlamp-pumped Nd:KGW laser crystal. The small size and high efficiency of this laser makes it an attractive source for a large number of applications such as communications and optical atmospheric studies.

  8. Transesterification of soybean oil over WO3 supported on AlPO4 as a solid acid catalyst.

    Science.gov (United States)

    Xie, Wenlei; Yang, Dong

    2012-09-01

    WO(3)/AlPO(4) catalysts were prepared by impregnation of AlPO(4) with ammonium metatungstate. Powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and thermo gravimetric and differential thermal analysis (TG-DTA) demonstrated that the tungsten compound was incorporated into AlPO(4) forming the catalyst with an enhanced acidity. When transesterification of soybean oil over the catalysts was performed, the catalyst with 30 wt.% WO(3) loading and calcined at 1073 K, exhibited the best catalytic activity with a conversion of 72.5%. The transesterification was optimal at 453 K for 5h with a methanol/oil ratio of 30:1 and catalyst dosage of 5 wt.%. Free fatty acid (FFA) and water did not affect the catalytic activity. The catalyst proved to be stable over four transesterification cycles as it lost only 4% of its activity after being reused four times. The catalyst could be used for the transesterification of low-cost oils for biodiesel production. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Photocatalytic activity and stability of TiO{sub 2} and WO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Carcel, Radu Adrian; Andronic, Luminita, E-mail: andronic-luminita@unitbv.ro; Duta, Anca, E-mail: a.duta@unitbv.ro

    2012-08-15

    Photocatalysis represents a viable option for complete degrading the dye molecules resulted in the textile industry, up to products that do not represent environmental threats. The photocatalytic degradation of methyl orange has been investigated using TiO{sub 2}, WO{sub 3} and mixed thin films. The photodegradation efficiency is examined in correlation with the experimental parameters (irradiation time, H{sub 2}O{sub 2} addition and stability), along with the morphology and crystallinity data. The H{sub 2}O{sub 2} addition increases the photodegradation efficiency by providing additional hydroxyl groups and further reducing the recombination of the electron-hole pairs by reacting with the electrons at the catalyst interface. To test the stability of the photocatalytic films in long time running processes, batch series of experiments were conducted using contact periods up to 9 days. The results show that the thin films maintained their photocatalytic properties confirming their stability and viability for up-scaling. Highlights: Black-Right-Pointing-Pointer TiO{sub 2}, WO{sub 3} and mixed thin films Black-Right-Pointing-Pointer We tested the photocatalytic activity and photocatalyst stability over a period up to 9 days of continuous irradiation. Black-Right-Pointing-Pointer The influence of medium pH and oxidizing agent (H{sub 2}O{sub 2}) was analyzed.

  10. α-Fe2O3 supported Bi2WO6 for photocatalytic degradation of gaseous benzene

    Science.gov (United States)

    Chen, Rong; Lu, Jun; Xiao, Jun; Zhu, Chengzhu; Peng, Shuchuan; Chen, Tianhu

    2017-09-01

    The Bi2WO6/α-Fe2O3 composite photocatalyst was synthesized by using goethite as a precursor through hydrothermal-calcination method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis reflection spectrometer (DRS), X-ray photoelectron spectroscopy (XPS) and N2 adsorption-desorption measurement (BET). These results indicated that the self-made composite photocatalysts had excellent catalytic performance of degradation of gaseous benzene. When benzene initial concentration at 50 mg/m3, over the α-FeOOH/Bi2WO6 with molar mass of 0.8:1, calcined at 350 °C for 2 h and the pH of precursor solution was 3, the benzene degradation rate reached 71.9% and the mineralization efficiency reached 67.7% after 220 min UV irradiation, respectively. The h+ and rad O2- generated in the photocatalytic system should be played a pivotal role for the enhanced photodegradation performance of gaseous benzene.

  11. Comparative analysis of crystal-field parameters for rare-earth ions at monoclinic sites in AB(WO4)2 crystals: II. Pr3+ and Nd3+ ions in KRE(WO4)2 (RE = Y or Gd), Pr3+ ions in M+Bi(XO4)2 (M+ = Li or Na and X = W or Mo), and Nd3+ ions in NaBi(WO4)2 and AgNd(WO4)2

    International Nuclear Information System (INIS)

    Rudowicz, Czesław; Gnutek, Paweł; Lewandowska, Monika; Karbowiak, Mirosław

    2014-01-01

    In part I, the crystal-field (CF) parameter (CFP) sets for important potential solid state laser systems Tm 3+ , Ho 3+ , and Er 3+ ions in KGd(WO 4 ) 2 and Tm 3+ ions in KLu(WO 4 ) 2 were thoroughly revisited using a general framework for the analysis of CF levels and CFP modeling. In this part the non-standard CFP sets for Pr 3+ and Nd 3+ ions in KR(WO 4 ) 2 (R = Y or Gd) and the standard CFP sets for Pr 3+ ions in M + Bi(XO 4 ) 2 (M + = Li or Na and X = W or Mo) and Nd 3+ ions in the related systems NaBi(WO 4 ) 2 and AgNd(WO 4 ) 2 are analyzed. Due to structural similarity of the hosts, the CFP values for a given trivalent rare-earth (RE 3+ ) ion should be quite close in these systems. However, the fitted (and model) CFP sets appear disparate for the systems in question. The standardization criteria are utilized to ensure direct comparability of the apparently disparate CFP sets reported in the literature. The CFP sets standardized by us are compared with the originally standard CFP sets for Pr 3+ and Nd 3+ ions in related AB(XO 4 ) 2 systems. Following part I, we argue that meaningful analysis of the mixed CFP sets, i.e. standard and non-standard ones, must take into account the intrinsic features of CF Hamiltonians for orthorhombic and lower symmetry cases, which have not been fully recognized in the literature as yet. The model or fitted CFP sets that belong to disparate regions in the CFP space are intrinsically incompatible, i.e. such sets should not be directly compared. The correlated alternative CFP sets are calculated using monoclinic standardization transformations. The closeness of the standardized CFP sets is assessed in a quantitative way using the closeness factors and the norms ratios. Comparative analysis of the monoclinic CFP sets reported for the titled ion–host systems is carried out and several inconsistencies in the previous studies are clarified. The CFP sets determined by standardization are utilized as starting sets for applications of

  12. Oral tungstate (Na2WO4) exposure reduces adaptive immune responses in mice after challenge.

    Science.gov (United States)

    Osterburg, Andrew R; Robinson, Chad T; Mokashi, Vishwesh; Stockelman, Michael; Schwemberger, Sandy J; Chapman, Gail; Babcock, George F

    2014-01-01

    Tungstate (WO²⁻₄) has been identified as a ground water contaminant at military firing ranges and can be absorbed by ingestion. In this study, C57BL6 mice were exposed to sodium tungstate (Na2WO4·2H2O) (0, 2, 62.5, 125, and 200 mg/kg/day) in their drinking water for an initial 28-day screen and in a one-generation (one-gen) model. Twenty-four hours prior to euthanasia, mice were intraperitoneally injected with Staphylococcal enterotoxin B (SEB) (20 μg/mouse) or saline as controls. After euthanasia, splenocytes and blood were collected and stained with lymphocyte and/or myeloid immunophenotyping panels and analyzed by flow cytometry. In the 28-day and one-gen exposure, statistically significant reductions were observed in the quantities of activated cytotoxic T-cells (TCTL; CD3(+)CD8(+)CD71(+)) and helper T-cells (TH; CD3(+)CD4(+)CD71(+)) from spleens of SEB-treated mice. In the 28-day exposures, CD71(+) TCTL cells were 12.87 ± 2.05% (SE) in the 0 tungstate (control) group compared to 4.44 ± 1.42% in the 200 mg/kg/day (p gen exposures, TCTL cells were 7.98 ± 0.49% and 6.33 ± 0.49% for P and F1 mice after 0 mg/kg/day tungstate vs 1.58 ± 0.23% and 2.52 ± 0.25% after 200 mg/kg/day of tungstate (p < 0.001). Similarly, TH cells were reduced to 6.21 ± 0.39% and 7.20 ± 0.76%, respectively, for the 0 mg/kg/day P and F1 mice, and 2.28 ± 0.41% and 2.85 ± 0.53%, respectively, for the 200 mg/kg/day tungstate P and F1 groups (p < 0.001). In delayed-type hypersensitivity Type IV experiments, tungstate exposure prior to primary and secondary antigen challenge significantly reduced footpad swelling at 20 and 200 mg/kg/day. These data indicate that exposure to tungstate can result in immune suppression that may, in turn, reduce host defense against pathogens.

  13. Subsolidus phase relations in the ZnO-MoO{sub 3}-B{sub 2}O{sub 3}, ZnO-MoO{sub 3}-WO{sub 3} and ZnO-WO{sub 3}-B{sub 2}O{sub 3} ternary systems

    Energy Technology Data Exchange (ETDEWEB)

    Xue Liping; Lin Zhang; Chen Dagui [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Huang Feng [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)], E-mail: fhuang@fjirsm.ac.cn; Liang Jingkui [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); International Center for Materials Physics, Academia Sinica, Shengyang 110016 (China)], E-mail: jkliang@aphy.iphy.ac.cn

    2008-06-30

    The subsolidus phase relations in the ZnO-MoO{sub 3}-B{sub 2}O{sub 3}, ZnO-MoO{sub 3}-WO{sub 3} and ZnO-WO{sub 3}-B{sub 2}O{sub 3} ternary systems have been investigated by the means of X-ray powder diffraction (XRD). There is no ternary compound in all the systems. There are five binary compounds and five tie lines in the ZnO-MoO{sub 3}-B{sub 2}O{sub 3} system. This system can be divided into six 3-phase regions. There are three binary compounds and three tie lines in the ZnO-MoO{sub 3}-WO{sub 3} system. This system can be divided into four 3-phase regions. There are four binary compounds and four tie lines in the ZnO-WO{sub 3}-B{sub 2}O{sub 3} system. This system can be divided into five 3-phase regions. The possible component regions for ZnO single crystal flux growth were discussed. The phase diagram of Zn{sub 3}B{sub 2}O{sub 6}-ZnWO{sub 4} pseudo-binary system has been constructed, and the result reveals this system is eutectic system. The eutectic temperature is 1007 deg. C and eutectic point component is 70 mol% Zn{sub 3}B{sub 2}O{sub 6}.

  14. Synthesis of WO{sub n}-WX{sub 2} (n=2.7, 2.9; X=S, Se) heterostructures for highly efficient green quantum dot light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Han, Shikui; Tan, Chaoliang; Zhang, Xiao; Chen, Junze; Huang, Ying; Chen, Bo; Luo, Zhimin; Ma, Qinglang; Sindoro, Melinda; Zhang, Hua [Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, Singapore (Singapore); Yang, Xuyong [Luminous. Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore (Singapore); Zhu, Yihan; Han, Yu [Advanced Membranes and Porous Materials Center, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia); Zhang, Hao; Li, Hai; Huang, Xiao; Huang, Wei [Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech) (China); Qi, Xiaoying [Singapore Institute of Manufacturing Technology, Singapore (Singapore); Sun, Xiao Wei [Luminous. Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore (Singapore); Dept. of Electrical and Electronic Engineering, College of Engineering, Southern Univ. of Science and Technology, Nanshan, Shenzhen, Guangdong (China)

    2017-08-21

    Preparation of two-dimensional (2D) heterostructures is important not only fundamentally, but also technologically for applications in electronics and optoelectronics. Herein, we report a facile colloidal method for the synthesis of WO{sub n}-WX{sub 2} (n=2.7, 2.9; X=S, Se) heterostructures by sulfurization or selenization of WO{sub n} nanomaterials. The WO{sub n}-WX{sub 2} heterostructures are composed of WO{sub 2.9} nanoparticles (NPs) or WO{sub 2.7} nanowires (NWs) grown together with single- or few-layer WX{sub 2} nanosheets (NSs). As a proof-of-concept application, the WO{sub n}-WX{sub 2} heterostructures are used as the anode interfacial buffer layer for green quantum dot light-emitting diodes (QLEDs). The QLED prepared with WO{sub 2.9} NP-WSe{sub 2} NS heterostructures achieves external quantum efficiency (EQE) of 8.53 %. To our knowledge, this is the highest efficiency in the reported green QLEDs using inorganic materials as the hole injection layer. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. First report on hemoglobin electrostatic immobilization on WO3 nanoparticles: application in the simultaneous determination of levodopa, uric acid, and folic acid.

    Science.gov (United States)

    Ghodsi, Javad; Rafati, Amir Abbas; Shoja, Yalda

    2016-05-01

    This work describes the first report about the simultaneous determination of levodopa (L-DOPA) with folic acid (FA) and uric acid (UA) based on electrocatalytic oxidation of L-DOPA with peroxidase properties of hemoglobin (Hb) in the presence of H2O2 as Hb activator. Bovine Hb was electrostatically immobilized on WO3 nanoparticles (WO3NPs) in pH between Hb and WO3NP isoelectric points, and subsequently, a carbon paste electrode (CPE) was modified with the obtained WO3NPs-Hb and multiwalled carbon nanotubes (MWCNTs). The resulting biosensor supplied a sensitive and suitably stable biosensor for the simultaneous determination of L-DOPA, UA, and FA. The obtained linear range and detection limit for L-DOPA, UA, and FA were completely acceptable, and the biosensor response time for these molecules was relatively short so that it reaches about 95 % of its maximum response in less than 10 s. The applicability of the current biosensor was confirmed with the determination of L-DOPA in the presence of fixed amounts of FA and UA in some real samples by the standard addition method.

  16. Degradation of Amaranth azo dye in water by heterogeneous photo-Fenton process using FeWO4 catalyst prepared by microwave irradiation.

    Science.gov (United States)

    da Cruz Severo, Eric; Anchieta, Chayene Gonçalves; Foletto, Vitória Segabinazzi; Kuhn, Raquel Cristine; Collazzo, Gabriela Carvalho; Mazutti, Marcio Antonio; Foletto, Edson Luiz

    2016-01-01

    FeWO4 particles were synthesized by a simple, rapid and facile microwave technique and their catalytic properties in heterogeneous photo-Fenton reaction were evaluated. This material was employed in the degradation of Amaranth azo dye. Individual and interactive effects of operational parameters such as pH, dye concentration and H2O2 dosage on the decolorization efficiency of Amaranth dye were evaluated by 2(3) central composite design. According to characterization techniques, a porous material and a well-crystallized phase of FeWO4 oxide were obtained. Regarding the photo-Fenton reaction assays, up to 97% color and 58% organic carbon removal were achieved in the best experimental conditions. In addition, the photo-Fenton process maintained treatment efficiency over five catalyst reuse cycles to indicate the durability of the FeWO4 catalyst. In summary, the results reveal that the synthesized FeWO4 material is a promising catalyst for wastewater treatment by heterogeneous photo-Fenton process.

  17. An in situ carbonization-replication method to synthesize mesostructured WO3/C composite as nonprecious-metal anode catalyst in PEMFC.

    Science.gov (United States)

    Cui, Xiangzhi; Hua, Zile; Wei, Chenyang; Shu, Zhu; Zhang, Liangxia; Chen, Hangrong; Shi, Jianlin

    2013-02-01

    A meostructured WO(3)/C composite with crystalline framework and high electric conductivity has been synthesized by a new in situ carbonization-replication route using the block copolymer (poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)) present in situ in the pore channels of mesoporous silica template as carbon source. X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, thermogravimetry differential thermal analysis, and N(2) adsorption techniques were adopted for the structural characterization. Cyclic voltammetry, chronoamperometry, and single-cell test for hydrogen electrochemical oxidation were adopted to characterize the electrochemical activities of the mesoporous WO(3)/C composite. The carbon content and consequent electric conductivity of these high-surface-area (108-130 m(2) g(-1)) mesostructured WO(3)/C composite materials can be tuned by variation of the duration of heat treatment, and the composites exhibited high and stable electrochemical catalytic activity. The single-cell test results indicated that the mesostructured WO(3)/C composites showed clear electrochemical catalytic activity toward hydrogen oxidation at 25 °C, which makes them potential non-precious-metal anode catalysts in proton exchange membrane fuel cell. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Critical difference between optoelectronic properties of α- and β-SnWO4semiconductors: A DFT/HSE06 and experimental investigation

    KAUST Repository

    Harb, Moussab

    2016-02-03

    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 approach DFPT) and employing the PBE and the range-separated hybrid exchange-correlation HSE06 functionals. The obtained bandgap, optical absorption coefficient, dielectric constant, and charge-carrier effective masses for β-SnWO4 exhibit data irreconcilable with the reported values: e.g., a large and direct bandgap of 4.30eV (UV-responsive), inconsistent with the values in the literature (visible-responsive). These properties obtained for β-SnWO4 are distinctive from those for α-SnWO4: an indirect bandgap of 1.52eV with higher charge mobilities. These data of intrinsic stoichiometric materials suggest that the literature reported nonstoichiometric materials where defects significantly influence the optoelectronic properties. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Investigation on optical band gap, photoluminescence properties and concentration quenching mechanism of Pb1 - x Tb3 +xWO4 green-emitting phosphors

    Science.gov (United States)

    Chanu, Thokchom Taru Taru; Rajmuhon Singh, N.

    2018-02-01

    A series of monophasic Tb3 + (2, 5, 7, 10 and 15 at%) doped PbWO4 phosphors were successfully prepared via hydrothermal method. X-ray diffraction patterns revealed that the prepared samples possess a high crystallinity with tetragonal scheelite-type structure. FT-IR and Raman analysis exhibited a Wsbnd O stretching peak of WO42 - group, which is also related to the scheelite structure. UV-visible diffuse reflectance spectra indicated a reduction in the optical band gap with the replacement of Pb2 + by Tb3 + ions. The presence of strong and intense emission peaks characteristic of Tb3 + with the dominant peak at 545 nm (green, 5D4 → 7F5 transition) under UV irradiation at 320 nm demonstrated an efficient energy transfer from the host to Tb3 + ions. Using Van Uitert's model, the concentration quenching mechanism between Tb3 + ions in PbWO4:Tb3 + phosphor was attributed to a dipole-dipole interaction and the critical distance was determined to be 12 Å. The decay lifetimes and CIE chromaticity co-ordinates of PbWO4:Tb3 + phosphors were also investigated in detail. These prepared materials might serve as a potential phosphor for LED applications.

  20. Enhanced Water Oxidation Photoactivity of Nano-Architectured α-Fe2O3-WO3 Composite Synthesized by Single-Step Hydrothermal Method

    Science.gov (United States)

    Rahman, Gul; Joo, Oh-Shim; Chae, Sang Youn; Shah, Anwar-ul-Haq Ali; Mian, Shabeer Ahmad

    2018-04-01

    This study reports the one-step in situ synthesis of a hematite-tungsten oxide (α-Fe2O3-WO3) composite on fluorine-doped tin oxide substrate via a simple hydrothermal method. Scanning electron microscopy images indicated that the addition of tungsten (W) precursor into the reaction mixture altered the surface morphology from nanorods to nanospindles. Energy-dispersive x-ray spectroscopy analysis confirmed the presence of W content in the composite. From the ultraviolet-visible spectrum of α-Fe2O3-WO3, it was observed that absorption began at ˜ 600 nm which corresponded to the bandgap energy of ˜ 2.01 eV. The α-Fe2O3-WO3 electrode demonstrated superior performance, with water oxidation photocurrent density of 0.80 mA/cm2 (at 1.6 V vs. reversible hydrogen electrode under standard illumination conditions; AM 1.5G, 100 mW/cm2) which is 2.4 times higher than α-Fe2O3 (0.34 mA/cm2). This enhanced water oxidation performance can be attributed to the better charge separation properties in addition to the large interfacial area of small-sized particles present in the α-Fe2O3-WO3 nanocomposite film.