WorldWideScience

Sample records for cuprous oxide crystals

  1. Magnetoexcitons in cuprous oxide

    Science.gov (United States)

    Schweiner, Frank; Main, Jörg; Wunner, Günter; Freitag, Marcel; Heckötter, Julian; Uihlein, Christoph; Aßmann, Marc; Fröhlich, Dietmar; Bayer, Manfred

    2017-01-01

    Two of the most striking experimental findings when investigating exciton spectra in cuprous oxide using high-resolution spectroscopy are the observability and the fine structure splitting of F excitons reported by J. Thewes et al. [Phys. Rev. Lett. 115, 027402 (2015), 10.1103/PhysRevLett.115.027402]. These findings show that it is indispensable to account for the complex valence band structure and the cubic symmetry of the solid in the theory of excitons. This is all the more important for magnetoexcitons, where the external magnetic field reduces the symmetry of the system even further. We present the theory of excitons in Cu2O in an external magnetic field and especially discuss the dependence of the spectra on the direction of the external magnetic field, which cannot be understood from a simple hydrogenlike model. Using high-resolution spectroscopy, we also present the corresponding experimental spectra for cuprous oxide in Faraday configuration. The theoretical results and experimental spectra are in excellent agreement as regards not only the energies but also the relative oscillator strengths. Furthermore, this comparison allows for the determination of the fourth Luttinger parameter κ of this semiconductor.

  2. Radiation annealing in cuprous oxide

    DEFF Research Database (Denmark)

    Vajda, P.

    1966-01-01

    Experimental results from high-intensity gamma-irradiation of cuprous oxide are used to investigate the annealing of defects with increasing radiation dose. The results are analysed on the basis of the Balarin and Hauser (1965) statistical model of radiation annealing, giving a square-root relati......-root relationship between the rate of change of resistivity and the resistivity change. The saturation defect density at room temperature is estimated on the basis of a model for defect creation in cuprous oxide....

  3. Evaluation of defects in cuprous oxide through exciton luminescence imaging

    Energy Technology Data Exchange (ETDEWEB)

    Frazer, Laszlo, E-mail: jl@laszlofrazer.com [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Lenferink, Erik J. [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Chang, Kelvin B. [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Poeppelmeier, Kenneth R. [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Stern, Nathaniel P. [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Ketterson, John B. [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Department of Electrical Engineering and Computer Science, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)

    2015-03-15

    The various decay mechanisms of excitons in cuprous oxide (Cu{sub 2}O) are highly sensitive to defects which can relax selection rules. Here we report cryogenic hyperspectral imaging of exciton luminescence from cuprous oxide crystals grown via the floating zone method showing that the samples have few defects. Some locations, however, show strain splitting of the 1s orthoexciton triplet polariton luminescence. Strain is reduced by annealing. In addition, annealing causes annihilation of oxygen and copper vacancies, which leads to a negative correlation between luminescence of unlike vacancies. - Highlights: • We use luminescence to observe defects in high quality cuprous oxide crystals. • Strain is reduced by annealing. • Annealing causes annihilation of oxygen and copper vacancies.

  4. Resistance switching of electrodeposited cuprous oxide

    Science.gov (United States)

    Yazdanparast, Sanaz

    In this work, the resistance switching behavior of electrodeposited cuprous oxide (Cu2O) thin films in Au/Cu2O/top electrode (Pt, Au-Pd, Al) cells was studied. After an initial FORMING process, the fabricated cells show reversible switching between a low resistance state (16.6 O) and a high resistance state (0.4 x 106 O). Changing the resistance states in cuprous oxide films depends on the magnitude of the applied voltage which corresponds to unipolar resistance switching behavior of this material. The endurance and retention tests indicate a potential application of the fabricated cells for nonvolatile resistance switching random access memory (RRAM). The results suggest formation and rupture of one or several nanoscale copper filaments as the resistance switching mechanism in the cuprous oxide films. At high electric voltage in the as-deposited state of Au/Cu 2O/Au-Pd cell structure, the conduction behavior follows Poole-Frenkel emission. Various parameters, such as the compliance current, the cuprous oxide microstructure, the cuprous oxide thickness, top electrode area, and top electrode material, affect the resistance switching characteristics. The required FORMING voltage is higher for Au/Cu2O/Al cell compared with the Au/Cu2O/Pt which is related to the Schottky behavior of Al contact with Cu2O. Cu2O nanowires in Au-Pt/ Cu 2O/Au-Pt cell also show resistance switching behavior, indicating scalable potential of this cell for usage as RRAM. After an initial FORMING process under an electric field of 3 x 106 V/m, the Cu2O nanowire is switched to the LRS. During the FORMING process physical damages are observed in the cell, which may be caused by Joule heating and gas evolution.

  5. Microwave Synthesis of Cuprous Oxide Micro-/Nanocrystals with Different Morphologies and Photocatalytic Activities

    Institute of Scientific and Technical Information of China (English)

    Qingwei Zhu; Yihe Zhang; Jiajun Wang; Fengshan Zhou; Paul K. Chu

    2011-01-01

    Cuprous oxide micro-/nanocrystals were synthesized by using a simple liquid phase reduction process under microwave irradiation. Copper sulfate was used as the starting materials and macromolecule surfactants served as the templates.The morphologies phase and optical properties of them are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet-visible diffuse reflection absorptive spectra (UV-vis/DRS), respectively. The crystals had four different shapes, namely spheres, strips, octahedrons, and dandelions. The photocatalytic behavior of the cuprous oxide particles were investigated by monitoring the degradation of rhodamine B. In spite of the different morphologies, all of the cuprous oxide micro-/nanocrystals exhibited photocatalytic activities under visible light irradiation in the following order: dandelions, strips, spheres, and octahedral crystals. The photocatalytic degradation rates of rhodamine B are 56.37%, 55.68%, 51.83% and 46.16%, respectively. The morphology affects significantly the photocatalytic performance.

  6. Nanometer-Thick Gold on Silicon as a Proxy for Single-Crystal Gold for the Electrodeposition of Epitaxial Cuprous Oxide Thin Films.

    Science.gov (United States)

    Switzer, Jay A; Hill, James C; Mahenderkar, Naveen K; Liu, Ying-Chau

    2016-06-22

    Single-crystal Au is an excellent substrate for electrochemical epitaxial growth due to its chemical inertness, but the high cost of bulk Au single crystals prohibits their use in practical applications. Here, we show that ultrathin epitaxial films of Au electrodeposited onto Si(111), Si(100), and Si(110) wafers can serve as an inexpensive proxy for bulk single-crystal Au for the deposition of epitaxial films of cuprous oxide (Cu2O). The Au films range in thickness from 7.7 nm for a film deposited for 5 min to 28.3 nm for a film deposited for 30 min. The film thicknesses are measured by low-angle X-ray reflectivity and X-ray Laue oscillations. High-resolution TEM shows that there is not an interfacial SiOx layer between the Si and Au. The Au films deposited on the Si(111) substrates are smoother and have lower mosaic spread than those deposited onto Si(100) and Si(110). The mosaic spread of the Au(111) layer on Si(111) is only 0.15° for a 28.3 nm thick film. Au films deposited onto degenerate Si(111) exhibit ohmic behavior, whereas Au films deposited onto n-type Si(111) with a resistivity of 1.15 Ω·cm are rectifying with a barrier height of 0.85 eV. The Au and the Cu2O follow the out-of-plane and in-plane orientations of the Si substrates, as determined by X-ray pole figures. The Au and Cu2O films deposited on Si(100) and Si(110) are both twinned. The films grown on Si(100) have twins with a [221] orientation, and the films grown on Si(110) have twins with a [411] orientation. An interface model is proposed for all Si orientations, in which the -24.9% mismatch for the Au/Si system is reduced to only +0.13% by a coincident site lattice in which 4 unit meshes of Au coincide with 3 unit meshes of Si. Although this study only considers the deposition of epitaxial Cu2O films on electrodeposited Au/Si, the thin Au films should serve as high-quality substrates for the deposition of a wide variety of epitaxial materials.

  7. Potentiostatic Deposition and Characterization of Cuprous Oxide Thin Films

    OpenAIRE

    2013-01-01

    Electrodeposition technique was employed to deposit cuprous oxide Cu2O thin films. In this work, Cu2O thin films have been grown on fluorine doped tin oxide (FTO) transparent conducting glass as a substrate by potentiostatic deposition of cupric acetate. The effect of deposition time on the morphologies, crystalline, and optical quality of Cu2O thin films was investigated.

  8. The Absorption of Benzotriazole on Copper and Cuprous Oxide

    Science.gov (United States)

    1988-07-01

    Cornell University, Ithaca INY, 14853 Copper surfaces are commonly treated with benzotriazole ( BTA ), 1. to inhibit cor- rosion. H1+ is thought to be...00 00 SIOFFICE OF NAVAL RESEARCH Contract N00014-82-K-0576 Technical Report No. 38 THE ADSORPTION OF BENZOTRIAZOLE ON COPPER AND CUPROUS OXIDE by M... Benzotriazole on Copper and Cuprous Oxide 12 7- `SONAL AUTHOR(S) M. C. Zonnevylle and R. Hoffmann 13a TYPE OF REPORT 13b TIME COVERED 14 DATE OF REPORT (Year

  9. Epitaxially aligned cuprous oxide nanowires for all-oxide, single-wire solar cells.

    Science.gov (United States)

    Brittman, Sarah; Yoo, Youngdong; Dasgupta, Neil P; Kim, Si-in; Kim, Bongsoo; Yang, Peidong

    2014-08-13

    As a p-type semiconducting oxide that can absorb visible light, cuprous oxide (Cu2O) is an attractive material for solar energy conversion. This work introduces a high-temperature, vapor-phase synthesis that produces faceted Cu2O nanowires that grow epitaxially along the surface of a lattice-matched, single-crystal MgO substrate. Individual wires were then fabricated into single-wire, all-oxide diodes and solar cells using low-temperature atomic layer deposition (ALD) of TiO2 and ZnO films to form the heterojunction. The performance of devices made from pristine Cu2O wires and chlorine-exposed Cu2O wires was investigated under one-sun and laser illumination. These faceted wires allow the fabrication of well-controlled heterojunctions that can be used to investigate the interfacial properties of all-oxide solar cells.

  10. Green chemistry synthesis of nano-cuprous oxide.

    Science.gov (United States)

    Ceja-Romero, L R; Ortega-Arroyo, L; Ortega Rueda de León, J M; López-Andrade, X; Narayanan, J; Aguilar-Méndez, M A; Castaño, V M

    2016-04-01

    Green chemistry and a central composite design, to evaluate the effect of reducing agent, temperature and pH of the reaction, were employed to produce controlled cuprous oxide (Cu2O) nanoparticles. Response surface method of the ultraviolet-visible spectroscopy is allowed to determine the most relevant factors for the size distribution of the nanoCu2O. X-ray diffraction reflections correspond to a cubic structure, with sizes from 31.9 to 104.3 nm. High-resolution transmission electron microscopy reveals that the different shapes depend strongly on the conditions of the green synthesis.

  11. Microwave-assisted synthesis and optical properties of cuprous oxide micro/nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Dandan [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China); Du, Yi, E-mail: duyi234@126.com [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China); Tian, Xiuying, E-mail: xiuyingt@yahoo.com [Department of Chemistry and Materials Science, Hunan Institute of Humanities Science and Technology, Loudi 417000 (China); Li, Zhongfu; Chen, Zhongtao; Zhu, Chaofeng [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China)

    2014-12-15

    Graphical abstract: Cuprous oxide micro/nanocrystals were fabricated by a facile and green microwave-assisted method using soluble starch as reductant and dispersant. Spheres with the diameter of about 100 and 600 nm, octahedron and truncated octahedron with the edge length of about 0.8–3 μm cuprous oxide micro/nanocrystals were successfully obtained. Microwave heating was proved to be a efficient method and was advantageous to the homogeneous nucleation. Growth mechanism of the prepared Cu{sub 2}O microcrystals were investigated carefully. Furthermore, the optical properties of the prepared cuprous oxide microcrystals were investigated by UV–vis diffuse reflectance spectroscopy, demonstrating that their band gaps of obtained samples were 1.96–2.07 eV, assigned to their different sizes and morphologies. - Abstract: Cuprous oxide micro/nanocrystals were fabricated by a facile and green microwave-assisted method using soluble starch as reductant and dispersant. It was observed that the addition amounts of NaOH had a prominent effect on the morphologies and size of cuprous oxide products, and microwave heating was proved to be a efficient method and was advantageous to the homogeneous nucleation. The as-obtained samples were characterized by X-ray diffraction (XRD), and field-emission scanning electron microscopy (FESEM). The results indicated that the samples were pure cuprous oxide. Spheres with the diameter of about 100 and 600 nm, octahedron and truncated octahedron with the edge length of about 0.8–3 μm cuprous oxide micro/nanocrystals were successfully obtained. Furthermore, the UV–vis diffuse reflectance spectroscopy was used to investigate the optical properties of the prepared cuprous oxide microcrystals, demonstrating that their band gaps of obtained samples were 1.96–2.07 eV, assigned to their different sizes and morphologies.

  12. Oxidation of cuprous stellacyanin by aminopolycarboxylatocobaltate(III) complexes.

    Science.gov (United States)

    Yoneda, G S; Mitchel, G L; Blackmer, G L; Holwerda, R A

    1978-01-01

    Rate parameters are reported for the oxidation of cuprous stellacyanin by Co(PDTA)-(k(25.0 degrees) = 17.9 M(-1)sec(-1), deltaH not equal to = 8.5 kcal/mol, deltaH not equal to = 8.5 kcal/mol, deltaS not equal to = -24 cal/mol-deg; pH 7.0, Mu 0.5 M) and Co(CyDTA)-(k(25.1 degrees) = 17.0 M(-1)sec(-1), deltaH not equal to = 8.7 kcal/mol, deltaS not equal to = -24 cal/mol-deg; pH 7.0 mu 0.5 M). The first order Co(PDTA)- and Co(CyDTA)- dependences observed over wide concentration ranges contrast with the saturation behavior reported previously for Co(EDTA)- as the oxidant. It is concluded that the- CH3 and -(CH2)4-substituents of PDTA and CyDTA, respectively, prevent the alkylated derivatives of Co(EDTA)- from hydrogen bonding with the reduced blue protein, causing precursor complex formation constants to fall far below that of 149M(-1) (25.1 degrees) observed for the EDTA complex. The similarity between deltaH not equal to and deltaS not equal to values for the oxidation of stellacyanin by Co(PDTA)- and Co(CyDTA)- indicates that the size of alkyl substituents linked to the carbon atoms of the EDTA ethylenediamine backbone has little influence on activation requirements for Cu(I) to Co(III) electron transfer. The electron transfer reactivity of aminopolycarboxylatocobalt(III) complexes with cuprous stellacyanin therefore appears to be linked to the accessibility of one or more of the ligated acetate groups to outer-sphere contact with the type 1 Cu(I) center. Saturation in kobsd vs. [oxidant] plots found for the reactions of Co(PDTA)- and Co(CyDTA)- with stellacyanin at pH 6 and at pH 7 in the presence of EDTA is attributed to the formation of "dead-end" oxidant-protein complexes.

  13. Enhancement of convective heat transfer coefficient of ethylene glycol base cuprous oxide (Cu2O) nanofluids

    Science.gov (United States)

    Hassan, Ali; Ramzan, Naveed; Umer, Asim; Ahmad, Ayyaz; Muryam, Hina

    2017-08-01

    The enhancement in the convective heat transfer coefficient of the ethylene glycol (EG) base cuprous oxide (Cu2O) nanofluids were investigated. The nanofluids of different volume concentrations i-e 1%, 2.5% and 4.5% were prepared by the two step method. Cuprous oxide (Cu2O) nanoparticles were ultrasonically stirred for four hours in the ethylene glycol (EG). The experimental study has been performed through circular tube geometry in laminar flow regime at average Reynolds numbers 36, 71 and 116. The constant heat flux Q = 4000 (W/m2) was maintained during this work. Substantial enhancement was observed in the convective heat transfer coefficient of ethylene glycol (EG) base cuprous oxide (Cu2O) nanofluids than the base fluid. The maximum 74% enhancement was observed in convective heat transfer coefficient at 4.5 vol% concentration and Re = 116.

  14. One-pot synthesis of cuprous oxide-reduced graphene oxide nanocomposite with enhanced photocatalytic and electrocatalytic performance

    Science.gov (United States)

    Han, Fugui; Li, Heping; Yang, Jun; Cai, Xiaodong; Fu, Li

    2016-03-01

    We report on the facile one-step synthesis of porous cuprous oxide nanoparticles on reduced graphene oxide (Cu2O-RGO) by synchronously reducing Cu2+ ions and GO with ethylene glycol. The basic chemical components, crystal structure and surface morphology of prepared nanocomposite was carefully characterized. The photocatalytic activities of the as-prepared nanocomposite was investigated by photodegrading methylene blue (MB) under visible light. The electrocatalytic property of the nanocomposite was investigated by electrocatalytic determination of acetaminophen. The results indicate that the corporation of RGO with Cu2O nanoparticles could high enhance the both photocatalytic and electrocatalytic properties. Moreover, we found that the content of RGO introduced into nanocomposite could highly affect the product properties.

  15. Cuprous oxide photovoltaic cells. Final report, September 1, 1978-November 30, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Trivich, D.

    1979-01-01

    The research described represents the beginning of a second phase of research on cuprous oxide photovoltaic cells. The first phase was concerned with the development of procedures of making Schottky barriers on isolated films of Cu/sub 2/O, including single crystals. It was found that properties of these Schottky barrier cells, in particular the barrier heights, were limited by chemical changes at the junction especially with metals of low work function which tend to be more active chemically, e.g., Al. The motivation of the present phase of the research was to construct junctions that would avoid this chemical degradation while maintaining electrical contact between the Cu/sub 2/O and a low work function material in order to attain larger barrier heights. Essentially the approach involved placing the Cu/sub 2/O in contact with a stable oxide. When this oxide is used as a thin layer between the Cu/sub 2/O and a top metal contact this gives an MIS structure. As another approach the other oxide can be an n-type semiconductor in thicker layers to form a heterojunction. Results are reported. (WHK)

  16. Towards printed perovskite solar cells with cuprous oxide hole transporting layers

    DEFF Research Database (Denmark)

    Wang, Yan; Xia, Zhonggao; Liang, Jun

    2015-01-01

    Solution-processed p-type metal oxide materials have shown great promise in improving the stability of perovskite-based solar cells and offering the feasibility for a low cost printing fabrication process. Herein, we performed a device modeling study on planar perovskite solar cells with cuprous ...

  17. Optical characterization of gold-cuprous oxide interfaces for terahertz emission applications

    NARCIS (Netherlands)

    Ramanandan, G.K.P.; Adam, A.J.L.; Ramakrishnan, G.; Petrik, P.; Hendrikx, R.; Planken, P.C.M.

    2014-01-01

    We show that the interface between gold and thermally formed cuprous oxide, which emits terahertz radiation when illuminated with ultrafast femtosecond lasers, is in fact an AuCu/Cu2O interface due to the formation of the thermal diffusion alloy AuCu. The alloy enables the formation of a Schottky-ba

  18. Picosecond nonlinear optical properties of cuprous oxide with different nano-morphologies

    Indian Academy of Sciences (India)

    P Harshavardhan Reddy; H Sekhar; D Narayana Rao

    2014-02-01

    Cuprous oxide nanoclusters, microcubes and microparticles were successfully synthesized by a simple co-precipitation method. Phase purity and crystallinity of the samples were studied by using X-ray powder diffraction. Transmission electron microscopy (TEM) images show different morphologies like nanoclusters, microcubes and microparticles. For linear and nonlinear optical measurements, the as-synthesized Cu2O with different morphologies were dispersed in isopropanol solution. The absorption spectrum recorded in the visible regions shows peaks that depend on the morphology of the particles and the peak shifts towards red region as one goes from nanoclusters to microparticles. Simple open-aperture Z-scan technique is used to measure nonlinear optical properties of cuprous oxide at 532 nm, 30 ps excitation at 10 Hz repetition rate. Cuprous oxide nanoclusters show reverse saturable absorption (RSA) behaviour, the microcubes and microparticles at a similar concentration exhibit saturable absorption (SA) type of behaviour at lower peak intensities and exhibit RSA within SA at higher peak intensities. The results show that the transition from SA to RSA can be ascribed to the two-photon absorption (TPA) process.

  19. Attenuated total reflectance spectroscopy of simultaneous processes: Corrosion inhibition of cuprous oxide by benzotriazole

    Science.gov (United States)

    Bratescu, Maria Antoaneta; Allred, Daniel B.; Saito, Nagahiro; Sarikaya, Mehmet; Takai, Osamu

    2008-03-01

    Attenuated total reflectance (ATR) spectroscopy was used to perform in situ studies of the corrosion inhibition of cuprous oxide (Cu 2O) by benzotriazole (BTA) in aqueous solution at concentrations from 1 to 20 μM. Because two separate processes occur simultaneously, that of Cu 2O corrosion and corrosion inhibition by BTA adsorption, the spectral information was subjected to deconvolution by a conjugate gradient minimization algorithm. Under these conditions, a solution phase concentration of 7-10 μM BTA nearly completely inhibited the corrosion of Cu 2O in deionized water. Using a Langmuir adsorption model, this represented only 25% of the maximally covered surface area.

  20. A photoemission study of benzotriazole on clean copper and cuprous oxide

    Science.gov (United States)

    Fang, Bo-Shung; Olson, Clifford G.; Lynch, David W.

    1986-11-01

    Photoemission spectra of benzotriazole (BTA) chemisorbed on clean Cu and on cuprous oxide were compared with the spectra of condensed- and gas-phase BTA. Chemisorbed BTA bonds to both Cu and Cu 2O via lone-pair orbitais on the nitrogen ring. The lack of a chemical shift for the π- orbitais indicates that BTA does not lie flat on the surface. We propose a model for the geometry and bonding of chemisorbed BTA which accounts for its corrosion inhibition on Cu, and for the corrosion inhibition, or lack of inhibition, by molecules similar to BTA.

  1. Numerical simulation of exciton dynamics in cuprous oxide at ultra low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Som, Sunipa

    2015-06-29

    This thesis is a theoretical investigation of the relaxation behaviour of excitons in Cuprous Oxide at ultra low temperatures when the excitons are confined within a potential trap and also in a homogeneous system. Under the action of deformation potential phonon scattering only, Bose Einstein Condensation (BEC) occurs for all temperatures in the investigated range. In the case of Auger decay, we do not find at any temperature a BEC due to the heating of the exciton gas. In the case of elastic and phonon-scattering together BEC occurs in this case of 0.1 K.

  2. Cuprous Oxide Scale up: Gram Production via Bulk Synthesis using Classic Solvents at Low Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hall, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Han, T. Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-05-07

    Cuprous oxide is a p-type semiconducting material that has been highly researched for its interesting properties. Many small-scale syntheses have exhibited excellent control over size and morphology. As the demand for cuprous oxide grows, the synthesis method need to evolve to facilitate large-scale production. This paper supplies a facile bulk synthesis method for Cu₂O on average, 1-liter reaction volume can produce 1 gram of particles. In order to study the shape and size control mechanisms on such a scale, the reaction volume was diminished to 250 mL producing on average 0.3 grams of nanoparticles per batch. Well-shaped nanoparticles have been synthesized using an aqueous solution of CuCl₂, NaOH, SDS surfactant, and NH₂OH-HCl at mild temperatures. The time allotted between the addition of NaOH and NH₂OH-HCl was determined to be critical for Cu(OH)2 production, an important precursor to the final produce The effects of stirring rates on a large scale was also analyzed during reagent addition and post reagent addition. A morphological change from rhombic dodecahedra to spheres occurred as the stirring speed was increased. The effects of NH₂OH-HCl concentration were also studied to control the etching effects of the final product.

  3. A Facile One Step Solution Route to Synthesize Cuprous Oxide Nanofluid

    Directory of Open Access Journals (Sweden)

    Shenoy U. Sandhya

    2013-05-01

    Full Text Available A cuprous oxide nanofluid stabilized by sodium lauryl sulfate, synthesized by using the one step method, has been reported. Nanofluids were synthesized by using a well‐ controlled surfactant‐assisted solution phase synthesis. The method involved reduction of copper acetate by glucose in a mixture of water and ethylene glycol serving as the base fluid. The synthesized fluid was characterized by X‐ray and electron diffraction techniques, in addition, transmission and field emission microscopic techniques and Fourier transform infra red spectroscopic analysis was undertaken. The rheological property, as well as the thermal conductivity of the fluid, were measured. The variation of reaction parameters considerably affected the size of the particles as well as the reaction rate. The uniform dispersion of the particles in the base fluid led to a stability period of three months under stationary state, augmenting the thermal conductivity of the nanofluid. The method is found to be simple, reliable and fast for the synthesis of Newtonian nanofluids containing cuprous oxide nanoparticles.

  4. Cuprous Sulfide/Reduced Graphene Oxide Hybrid Nanomaterials: Solvothermal Synthesis and Enhanced Electrochemical Performance

    Science.gov (United States)

    He, Zhanjun; Zhu, Yabo; Xing, Zheng; Wang, Zhengyuan

    2016-01-01

    The cuprous sulfide nanoparticles (CuS NPs)-decorated reduced graphene oxide (rGO) nanocomposites have been successfully prepared via a facile and efficient solvothermal synthesis method. Scanning electron microscopy and transmission electron microscopy images demonstrated that CuS micronspheres composed of nanosheets and distributed on the rGO layer in well-monodispersed form. Fourier-transform infrared spectroscopy analyses and x-ray photoelectron spectroscopy showed that graphene oxide (GO) had been reduced to rGO. The electrochemical performances of CuS/rGO nanocomposites were investigated by cyclic voltammetry and charge/discharge techniques, which showed that the specific capacitance of CuS/rGO nanocomposites was enhanced because of the introduction of rGO.

  5. Intrinsic Defect Engineering of Cuprous Oxide to Enhance Electrical Transport Properties for Photovoltaic Applications

    Energy Technology Data Exchange (ETDEWEB)

    Lloyd, Michael A.; Siah, Sin-Cheng; Brandt, Riley E.; Serdy, James; Johnston, Steve W.; Lee, Yun Seog; Buonassisi, Tonio

    2014-06-08

    Intrinsic point-defect species in cuprous oxide films are manipulated based on their thermodynamic properties via the implementation of a controlled annealing process. A wide range of electrical properties is demonstrated, with a window suitable for high-quality solar cell devices. A variation of carrier concentration over two orders of magnitude is demonstrated. Minority carrier lifetime is investigated by means of microwave photoconductance decay measurements, demonstrating a strong correlation with carrier concentration. Spectrally resolved photoluminescence yields are analyzed to provide insight into lifetime limiting mechanisms as a function of Cu2O processing parameters. Hall measurements of carrier mobility and concentration are taken at room temperature to provide insight into the effect of these processing conditions on net ionized defect concentration.

  6. Investigations of the interaction between cuprous oxide nanoparticles and Staphylococcus aureus

    Institute of Scientific and Technical Information of China (English)

    SHEN ChengLing; LI YuanFang; QI WenJing; HUANG ChengZhi

    2009-01-01

    Cuprous oxide nanoparticles of 30-50 nm in size were prepared in the presence of cetyltrimethylammonium bromide (CTAB).By taking Staphylococcus aureus (S.a),which always causes a variety of suppurative infections and toxinoses in humans,as a model bioparticle,the negative bioeffect of nano-Cu2O on S.a cells was evaluated,and minimal inhibitory concentration (MIC) was determined by imitating the MIC of antibiotics.Cellularity and bactericidal effect were measured by flow cytometry (FCM),dark field light scattering imaging and SEM photography.The results showed that nano-Cu2O particles may,by absorbing on the cell surface,impair the cell wall,damage the cell membrane,and finally increase permeability of the cell membrane,thus leading to a decrease in the viability of bacteria in the nano-Cu2O solution.

  7. Investigations of the interaction between cuprous oxide nanoparticles and Staphylococcus aureus

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Cuprous oxide nanoparticles of 30-50 nm in size were prepared in the presence of cetyltrimethylam-monium bromide (CTAB). By taking Staphylococcus aureus (S.a), which always causes a variety of suppurative infections and toxinoses in humans, as a model bioparticle, the negative bioeffect of nano-Cu2O on S.a cells was evaluated, and minimal inhibitory concentration (MIC) was determined by imitating the MIC of antibiotics. Cellularity and bactericidal effect were measured by flow cytometry (FCM), dark field light scattering imaging and SEM photography. The results showed that nano-Cu2O particles may, by absorbing on the cell surface, impair the cell wall, damage the cell membrane, and finally increase permeability of the cell membrane, thus leading to a decrease in the viability of bacteria in the nano-Cu2O solution.

  8. Facile fabrication of electrolyte-gated single-crystalline cuprous oxide nanowire field-effect transistors

    Science.gov (United States)

    Stoesser, Anna; von Seggern, Falk; Purohit, Suneeti; Nasr, Babak; Kruk, Robert; Dehm, Simone; Wang, Di; Hahn, Horst; Dasgupta, Subho

    2016-10-01

    Oxide semiconductors are considered to be one of the forefront candidates for the new generation, high-performance electronics. However, one of the major limitations for oxide electronics is the scarcity of an equally good hole-conducting semiconductor, which can provide identical performance for the p-type metal oxide semiconductor field-effect transistors as compared to their electron conducting counterparts. In this quest, here we present a bulk synthesis method for single crystalline cuprous oxide (Cu2O) nanowires, their chemical and morphological characterization and suitability as active channel material in electrolyte-gated, low-power, field-effect transistors (FETs) for portable and flexible logic circuits. The bulk synthesis method used in the present study includes two steps: namely hydrothermal synthesis of the nanowires and the removal of the surface organic contaminants. The surface treated nanowires are then dispersed on a receiver substrate where the passive electrodes are structured, followed by printing of a composite solid polymer electrolyte (CSPE), chosen as the gate insulator. The characteristic electrical properties of individual nanowire FETs are found to be quite interesting including accumulation-mode operation and field-effect mobility of 0.15 cm2 V-1 s-1.

  9. Nonlinear optical properties of bulk cuprous oxide using single beam Z-scan at 790 nm

    Energy Technology Data Exchange (ETDEWEB)

    Serna, J.; Rueda, E. [Grupo de Óptica y Fotónica, Instituto de Física, Universidad de Antioquia U de A, Calle 70 No. 52-21, Medellín (Colombia); García, H., E-mail: hgarcia@siue.edu [Department of Physics, Southern Illinois University, Edwardsville, Illinois 60026 (United States)

    2014-11-10

    The two-photon absorption (TPA) coefficient β and the nonlinear index of refraction n{sub 2} for bulk cuprous oxide (Cu{sub 2}O) direct gap semiconductor single crystal have been measured by using a balance-detection Z-scan single beam technique, with an excellent signal to noise ratio. Both coefficients were measured at 790 nm using a 65 fs laser pulse at a repetition rate of 90.9 MHz, generated by a Ti:Sapphire laser oscillator. The experimental values for β were explained by using a model that includes allowed-allowed, forbidden-allowed, and forbidden-forbidden transitions. It was found that the forbidden-forbidden transition is the dominant mechanism, which is consistent with the band structure of Cu{sub 2}O. The low value for β found in bulk, as compared with respect to thin film, is explained in terms of the structural change in thin films that result in opposite parities of the conduction and valence band. The n{sub 2} is also theoretically calculated by using the TPA dispersion curve and the Kramers-Kronig relations for nonlinear optics.

  10. Cuprous oxide nanoparticle-inhibited melanoma progress by targeting melanoma stem cells.

    Science.gov (United States)

    Yu, Bin; Wang, Ye; Yu, Xinlu; Zhang, Hongxia; Zhu, Ji; Wang, Chen; Chen, Fei; Liu, Changcheng; Wang, Jingqiang; Zhu, Haiying

    2017-01-01

    Recent studies have shown that metal and metal oxide have a potential function in antitumor therapy. Our previous studies demonstrated that cuprous oxide nanoparticles (CONPs) not only selectively induce apoptosis of tumor cells in vitro but also inhibit the growth and metastasis of melanoma by targeting mitochondria with little hepatic and renal toxicities in mice. As a further study, our current research revealed that CONPs induced apoptosis of human melanoma stem cells (CD271(+/high) cells) in A375 and WM266-4 melanoma cell lines and could significantly suppress the expression of MITF, SOX10 and CD271 involved in the stemness maintenance and tumorigenesis of melanoma stem cells. CD271(+/high) cells could accumulate more CONPs than CD271(-/low) through clathrin-mediated endocytosis. In addition, lower dosage of CONPs exhibited good anti-melanoma effect by decreasing the cell viability, stemness and tumorigenesis of A375 and WM266-4 cells through reducing the expression of SOX10, MITF, CD271 and genes in MAPK pathway involved in tumor progression. Finally, CONPs obviously suppressed the growth of human melanoma in tumor-bearing nonobese diabetic-severe combined immunodeficiency (NOD-SCID) mice, accompanied with tumors structural necrosis and fibrosis remarkably and decreased expression of CD271, SOX10 and MITF. These results above proved the effectiveness of CONPs in inhibiting melanoma progress through multiple pathways, especially through targeting melanoma stem cells.

  11. Towards printed perovskite solar cells with cuprous oxide hole transporting layers: a theoretical design

    Science.gov (United States)

    Wang, Yan; Xia, Zhonggao; Liang, Jun; Wang, Xinwei; Liu, Yiming; Liu, Chuan; Zhang, Shengdong; Zhou, Hang

    2015-05-01

    Solution-processed p-type metal oxide materials have shown great promise in improving the stability of perovskite-based solar cells and offering the feasibility for a low cost printing fabrication process. Herein, we performed a device modeling study on planar perovskite solar cells with cuprous oxide (Cu2O) hole transporting layers (HTLs) by using a solar cell simulation program, wxAMPS. The performance of a Cu2O/perovskite solar cell was correlated to the material properties of the Cu2O HTL, such as thickness, carrier mobility, mid-gap defect, and doping concentrations. The effect of interfacial defect densities on the solar cell performance was also investigated. Our simulation indicates that, with an optimized Cu2O HTL, high performance perovskite solar cells with efficiencies above 13% could be achieved, which shows the potential of using Cu2O as an alternative HTL over other inorganic materials, such as NiOx and MoOx. This study provides theoretical guidance for developing perovskite solar cells with inorganic hole transporting materials via a printing process.

  12. Improvement in structural and electrical properties of cuprous oxide-coated multiwalled carbon nanotubes

    Indian Academy of Sciences (India)

    Shivani Dhall; Neena Jaggi

    2014-10-01

    In the present work, cuprous oxide (Cu2O) nanoparticles are coated on multi-walled carbon nanotubes (MWCNTs) using Fehling’s reaction. The coating of Cu2O nanoparticles on the nanotubes was confirmed by SEM and X-ray diffraction (XRD) spectra. The calculated D/G ratio of Cu2O (using 3% CuSO4 by wt)-coated MWCNTs by Raman spectra is found to decrease to 0.94 as compared to 1.14 for pristine MWCNTs. It shows that the presence of Cu2O nanoparticles on nanotubes decreases the inherent defects present in the form of some pentagons/heptagons in the honeycomb hexagonal carbon atoms in the structure of graphene sheets of MWCNTs and increases the crystalline nature of MWCNTs, which is also confirmed by the XRD peaks. Whereas the value of D/G ratio increases to 1.39 for sample 2 (using 5% CuSO4 by wt), which represents the structural deformation. Moreover, the electrical conductivity of MWCNTs was increased by 3 times after coating the nanotubes with Cu2O (using 3% CuSO4 by wt).

  13. Structural, Optical and Electrical Properties of Nanocrystalline Cuprous Oxide Thin Film Deposited By Chemical Method

    Directory of Open Access Journals (Sweden)

    Prakash Bansilal Ahirrao

    2010-06-01

    Full Text Available Cuprous oxide (Cu2O is an interesting p-type semiconductor material used in solar cell applications.  The Modified Chemical Bath Deposition (M-CBD method is suitable for growing thin multilayer structure due to low deposition temperature. This method does not require any sophisticated instrument and substrate need not to be conductive. The nanocrystalline Cu2O thin films were deposited on glass substrates by M-CBD method. The deposited films were characterized by different characterization techniques to study structural, surface morphological, optical and electrical properties. The structural studies show that, the formation of Cu2O thin films with an average crystallite size of 14 nm. Optical studies show a direct band gap 2.48 eV. The room temperature electrical resistivity is of the order of 1.3 kW-cm and activation energy 0.33 eV. The films exhibit p-type electrical conductivity as seen by thermo-emf measurements.

  14. Parameters controlling microstructures and resistance switching of electrodeposited cuprous oxide thin films

    Science.gov (United States)

    Yazdanparast, Sanaz

    2016-12-01

    Cuprous oxide (Cu2O) thin films were electrodeposited cathodically from a highly alkaline bath using tartrate as complexing agent. Different microstructures for Cu2O thin films were achieved by varying the applied potential from -0.285 to -0.395 V versus a reference electrode of Ag/AgCl at 50 °C in potentiostatic mode, and separately by changing the bath temperature from 25 to 50 °C in galvanostatic mode. Characterization experiments showed that both grain size and orientation of Cu2O can be controlled by changing the applied potential. Applying a high negative potential of -0.395 V resulted in smaller grain size of Cu2O thin films with a preferred orientation in [111] direction. An increase in the bath temperature in galvanostatic electrodeposition increased the grain size of Cu2O thin films. All the films in Au/Cu2O/Au-Pd cell showed unipolar resistance switching behavior after an initial FORMING process. Increasing the grain size of Cu2O thin films and decreasing the top electrode area increased the FORMING voltage and decreased the current level of high resistance state (HRS). The current in low resistance state (LRS) was independent of the top electrode area and the grain size of deposited films, suggesting a filamentary conduction mechanism in unipolar resistance switching of Cu2O.

  15. Carbon-layer-protected cuprous oxide nanowire arrays for efficient water reduction

    KAUST Repository

    Zhang, Zhonghai

    2013-02-26

    In this work, we propose a solution-based carbon precursor coating and subsequent carbonization strategy to form a thin protective carbon layer on unstable semiconductor nanostructures as a solution to the commonly occurring photocorrosion problem of many semiconductors. A proof-of-concept is provided by using glucose as the carbon precursor to form a protective carbon coating onto cuprous oxide (Cu2O) nanowire arrays which were synthesized from copper mesh. The carbon-layer-protected Cu2O nanowire arrays exhibited remarkably improved photostability as well as considerably enhanced photocurrent density. The Cu2O nanowire arrays coated with a carbon layer of 20 nm thickness were found to give an optimal water splitting performance, producing a photocurrent density of -3.95 mA cm-2 and an optimal photocathode efficiency of 0.56% under illumination of AM 1.5G (100 mW cm-2). This is the highest value ever reported for a Cu 2O-based electrode coated with a metal/co-catalyst-free protective layer. The photostability, measured as the percentage of the photocurrent density at the end of 20 min measurement period relative to that at the beginning of the measurement, improved from 12.6% on the bare, nonprotected Cu2O nanowire arrays to 80.7% on the continuous carbon coating protected ones, more than a 6-fold increase. We believe that the facile strategy presented in this work is a general approach that can address the stability issue of many nonstable photoelectrodes and thus has the potential to make a meaningful contribution in the general field of energy conversion. © 2013 American Chemical Society.

  16. Cytotoxicity of cuprous oxide nanoparticles to fish blood cells: hemolysis and internalization

    Energy Technology Data Exchange (ETDEWEB)

    Chen Liqiang, E-mail: chenlq@ynu.edu.cn; Kang Bin [Yunnan University, Asian International Rivers Center, Yunnan Key Laboratory of International Rivers and Trans-boundary Eco-security (China); Ling Jian [Yunnan University, College of Chemistry and Chemical Engineering (China)

    2013-03-15

    Cuprous oxide nanoparticles (Cu{sub 2}O NPs) possess unique physical and chemical properties which are employed in a broad variety of applications. However, little is known about the adverse effects of Cu{sub 2}O NPs on organisms. In the current study, in vitro cytotoxicity of Cu{sub 2}O NPs (ca. 60 nm in diameter) to the blood cells of freshwater fish Carassius auratus was evaluated. A concentration-dependent hemolytic activity of Cu{sub 2}O NPs to red blood cells (RBCs) and the phagocytosis of Cu{sub 2}O NPs by leukocytes were revealed. The results showed that dosages of Cu{sub 2}O NPs greater than 40 {mu}g/mL were toxic to blood cells, and could cause serious membrane damage to RBCs. The EC{sub 50} value of Cu{sub 2}O NPs as obtained from RBCs and whole blood exposure was 26 and 63 {mu}g/mL, respectively. The generation of reactive oxygen species and the direct interaction between Cu{sub 2}O NPs and the cell membrane were suggested as the possible mechanism for cytotoxicity, and the intrinsic hemolytic active of Cu{sub 2}O NPs was the main contributor to the toxicity rather than solubilized copper ions. The adsorption of plasma proteins on the surfaces of Cu{sub 2}O NPs led to their aggregation in whole blood, and aggregate formation can significantly alleviate the hemolytic effect and subsequently mediate the phagocytosis of Cu{sub 2}O NPs by leukocytes.

  17. Reduced graphene oxide–cuprous oxide composite via facial deposition for photocatalytic dye-degradation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, MingYan, E-mail: mingyanlyg@hotmail.com [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, Australian Institute of Innovative Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Huang, JunRao; Tong, ZhiWei [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Li, WeiHua [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Chen, Jun, E-mail: junc@uow.edu.au [Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, Australian Institute of Innovative Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia)

    2013-08-15

    Highlights: •Cubic Cu{sub 2}O were effectively loaded on n-propylamine (PA) intercalated graphene oxide. •The addition of PA on the carbon sheets supports the stable structure of the composites. •Cu{sub 2}O/PA/rGO showed superior adsorption capacity and photocatalytic activity. -- Abstract: Cubic Cu{sub 2}O nanoparticles have been successfully synthesized on n-propylamine (PA) intercalated graphene oxide (GO) with uniform distribution followed with a subsequent hydrazine hydrate reduction process to generate Cu{sub 2}O/PA/rGO composite. For comparison, Cu{sub 2}O conjugated reduced graphene oxide (Cu{sub 2}O/rGO) composite was also synthesized using the same method. The as-prepared Cu{sub 2}O/PA/rGO and Cu{sub 2}O/rGO nanocomposites are characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) spectroscopy, infrared spectroscopy (IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area analysis, and Electrochemical impedance spectra (EIS) measurements. UV/vis diffuse reflectance spectroscopy was employed to estimate band gap energies of cuprous oxide composites. The results show that the intercalation of PA into the layered GO increases the surface area of the composites and provides an efficient strategy to load Cu{sub 2}O due to the large and uniform distribution of active sites for anchoring copper ions. The surface area of the Cu{sub 2}O/PA/rGO (123 m{sup 2}/g) nanocomposite was found to be almost 2.5 times higher than that of Cu{sub 2}O/rGO (55.7 m{sup 2}/g). The as-prepared Cu{sub 2}O/PA/rGO show significant improvement on both adsorption capacity and photocatalytic activity towards organic pigment pollution compared with Cu{sub 2}O/rGO under identical performance conditions.

  18. Hydrometallurgical process for the recycling of copper using anodic oxidation of cuprous ammine complexes and flow-through electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Oishi, T.; Yaguchi, M.; Koyama, K.; Tanaka, M. [Metals Recycling Group, Research Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Lee, J.-C. [Minerals and Materials Processing Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), 30 Gajeong-dong, Yuseong-ku, Daejeon 305-350 (Korea)

    2008-01-01

    Flow-through electrolysis for copper electrowinning from cuprous ammine complex was studied in order to develop a hydrometallurgical copper recycling process using an ammoniacal chloride solution, focusing on the anodic oxidation of cuprous to cupric ammine complexes. The current efficiency of this anodic oxidation was 96% at a current density of 200 A m{sup -2} under a batch condition. In a flow-through electrolysis using a sub-liter cell and a carbon felt anode, the anodic current efficiency increased with the flow rate and was typically higher than 97%. This tendency was explained by the backward flow of the cupric ammine complex, which was formed on the anode, through the diaphragm. The anodic overpotential was lower than 0.3 V even at an apparent current density of 1500 A m{sup -2}. A similar current efficiency and overpotential were also achieved in a liter scale cell, which indicates the scale flexibility of this electrolysis. The power consumption requirements for copper electrowinning in this cell were 460 and 770 kWh t{sup -1} at the current densities of 250 and 500 A m{sup -2}, respectively, which were much lower than that of the conventional copper electrowinning despite the longer interpolar distance. (author)

  19. Plasmon-induced selective carbon dioxide conversion on earth-abundant aluminum-cuprous oxide antenna-reactor nanoparticles.

    Science.gov (United States)

    Robatjazi, Hossein; Zhao, Hangqi; Swearer, Dayne F; Hogan, Nathaniel J; Zhou, Linan; Alabastri, Alessandro; McClain, Michael J; Nordlander, Peter; Halas, Naomi J

    2017-06-21

    The rational combination of plasmonic nanoantennas with active transition metal-based catalysts, known as 'antenna-reactor' nanostructures, holds promise to expand the scope of chemical reactions possible with plasmonic photocatalysis. Here, we report earth-abundant embedded aluminum in cuprous oxide antenna-reactor heterostructures that operate more effectively and selectively for the reverse water-gas shift reaction under milder illumination than in conventional thermal conditions. Through rigorous comparison of the spatial temperature profile, optical absorption, and integrated electric field enhancement of the catalyst, we have been able to distinguish between competing photothermal and hot-carrier driven mechanistic pathways. The antenna-reactor geometry efficiently harnesses the plasmon resonance of aluminum to supply energetic hot-carriers and increases optical absorption in cuprous oxide for selective carbon dioxide conversion to carbon monoxide with visible light. The transition from noble metals to aluminum based antenna-reactor heterostructures in plasmonic photocatalysis provides a sustainable route to high-value chemicals and reaffirms the practical potential of plasmon-mediated chemical transformations.Plasmon-enhanced photocatalysis holds promise for the control of chemical reactions. Here the authors report an Al@Cu2O heterostructure based on earth abundant materials to transform CO2 into CO at significantly milder conditions.

  20. Preparation of 3D nanoporous copper-supported cuprous oxide for high-performance lithium ion battery anodes.

    Science.gov (United States)

    Liu, Dequan; Yang, Zhibo; Wang, Peng; Li, Fei; Wang, Desheng; He, Deyan

    2013-03-01

    Three-dimensional (3D) nanoporous architectures can provide efficient and rapid pathways for Li-ion and electron transport as well as short solid-state diffusion lengths in lithium ion batteries (LIBs). In this work, 3D nanoporous copper-supported cuprous oxide was successfully fabricated by low-cost selective etching of an electron-beam melted Cu(50)Al(50) alloy and subsequent in situ thermal oxidation. The architecture was used as an anode in lithium ion batteries. In the first cycle, the sample delivered an extremely high lithium storage capacity of about 2.35 mA h cm(-2). A high reversible capacity of 1.45 mA h cm(-2) was achieved after 120 cycles. This work develops a promising approach to building reliable 3D nanostructured electrodes for high-performance lithium ion batteries.

  1. Optical Study of Cuprous Oxide and Ferric Oxide Based Materials for Applications in Low Cost Solar Cells

    Science.gov (United States)

    Than, Thi Cuc; Bui, Bao Thoa; Wegmuller, Benjamin; Nguyen, Minh Hieu; Hoang Ngoc, Lam Huong; Bui, Van Diep; Nguyen, Quoc Hung; Hoang, Chi Hieu; Nguyen-Tran, Thuat

    2016-05-01

    One of the interesting forms of cuprous oxide and ferric oxide based materials is CuFeO2 which can be a delafossite-type compound and is a well known p-type semiconductor. This compound makes up an interesting family of materials for technological applications. CuFeO2 thin films recently gained renewed interest for potential applications in solar cell devices especially as absorption layers. One of the interesting facts is that CuFeO2 is made from cheap materials such as copper and iron. In this study, CuFeO2 thin films are intentionally deposited on corning glass and silicon substrates by the radio-frequency and direct current sputtering method with complicated and well developed co-sputtering recipes. The deposition was performed at room temperature which leads to an amorphous phase with extremely low roughness and high density. The films also were annealed at 500°C in 5% H2 in Ar for the passivation. A detailed optical study was performed on these thin films by spectroscopic ellipsometry and by ultra-violet visible near infrared spectroscopy. Depending on sputtering conditions, the direct band gap was extrapolated to be from 1.96 eV to 2.2 eV and 2.92 eV to 2.96 eV and the indirect band gap is about 1.22 eV to 1.42 eV. A good electrical conduction is also observed which is suitable for solar cell applications. In future more study on the structural properties will be carried out in order to fully understand these materials.

  2. Cuprous oxide nanoparticles inhibit prostate cancer by attenuating the stemness of cancer cells via inhibition of the Wnt signaling pathway

    Science.gov (United States)

    Wang, Ye; Yang, Qi-Wei; Yang, Qing; Zhou, Tie; Shi, Min-Feng; Sun, Chen-Xia; Gao, Xiu-Xia; Cheng, Yan-Qiong; Cui, Xin-Gang; Sun, Ying-Hao

    2017-01-01

    Disordered copper metabolism plays a critical role in the development of various cancers. As a nanomedicine containing copper, cuprous oxide nanoparticles (CONPs) exert ideal antitumor pharmacological effects in vitro and in vivo. Prostate cancer is a frequently diagnosed male malignancy prone to relapse, and castration resistance is the main reason for endocrine therapy failure. However, whether CONPs have the potential to treat castration-resistant prostate cancer is still unknown. Here, using the castration-resistant PC-3 human prostate cancer cell line as a model, we report that CONPs can selectively induce apoptosis and inhibit the proliferation of cancer cells in vitro and in vivo without affecting normal prostate epithelial cells. CONPs can also attenuate the stemness of cancer cells and inhibit the Wnt signaling pathway, both of which highlight the great potential of CONPs as a new clinical castration-resistant prostate cancer therapy.

  3. Novel Facile Technique for Synthesis of Stable Cuprous Oxide (Cu2O Nanoparticles – an Ageing Effect

    Directory of Open Access Journals (Sweden)

    Sachin S. Sawant

    2016-03-01

    Full Text Available A novel facile method to synthesize stable phase of Cuprous Oxide (Cu2O nanoparticles at room temperature is demonstrated. The structural and optical properties of (Cu2O nanoparticles were investigated by using X-ray diffraction (XRD, UV-VIS Spectroscopy. XRD analysis has indexed nanocrystalline nature of cubical phase Cu2O with an average edge length of about 20 nm. The Scanning Electron Microscopy (SEM measurements also ascertain the cubical morphology. The Fourier Transform Infrared Spectroscopy (FTIR affirms the presence of characteristic functional group of Cu2O. The absorbance peak at 485 nm in UV-VIS spectra also confirms the Cu2O synthesis. Furthermore, UV-VIS absorbance spectra at different ageing time substantiate the phase stability of Cu2O nanoparticles. The ageing leads to blue shift of absorbance peak mainly due to decrease in Cu2O particle size with no additional absorbance peak in UV-VIS spectra indicating the formation of secondary phase. The reduction in particle size may be attributed to tiny conversion Cu2O to CuO. The energy band gap measurements from Tauc plots for Cu2O nanoparticles shows the increasing trend (2.5 eV to 2.8 eV with ageing time (2 months, owing to quantum confinement effects.

  4. Preparation of cuprous oxides with different sizes and their behaviors of adsorption, visible-light driven photocatalysis and photocorrosion

    Science.gov (United States)

    Huang, Lei; Peng, Feng; Yu, Hao; Wang, Hongjuan

    2009-01-01

    Cuprous oxide (Cu 2O) nanoparticles and microparticles have been prepared by liquid phase chemical synthesis. The samples were characterized by means of SEM, XRD, UV/DRS and XPS. It was presented that as-prepared Cu 2O nanoparticles are substantially stable in ambient atmosphere and the Cu + as main state exists on the surface of Cu 2O nanoparticles. As-prepared Cu 2O microparticles can exist stably as a Cu 2O/CuO core/shell structure; and the Cu 2+ as main state exists on the surface of Cu 2O microparticles. The behaviors of adsorption, photocatalysis and photocorrosion of Cu 2O particles with different sizes were investigated in detail. The results show that Cu 2O nanoparticles are very easy to photocorrosion during the photocatalytic reaction, which cannot be used as photocatalyst directly to degrade organic compound, although as-prepared Cu 2O nanoparticles exhibit special property of adsorption. Cu 2O microparticles have a higher photocatalytic activity than Cu 2O nanoparticles because of its slower photocorrosion rate, although Cu 2O microparticles have much lower adsorption capacity than Cu 2O nanoparticles. The mechanisms of photocatalysis and photocorrosion for Cu 2O under visible light were also discussed.

  5. A novel reducing graphene/polyaniline/cuprous oxide composite hydrogel with unexpected photocatalytic activity for the degradation of Congo red

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Jie; Xie, Anjian; Li, Shikuo; Huang, Fangzhi; Cao, Juan; Shen, Yuhua, E-mail: yhshen@ahu.edu.cn

    2016-01-01

    Graphical abstract: Excellent photocatalytic activity of the RGO/PANI/Cu{sub 2}O composite hydrogel for CR degradation under UV–vis light irradiation. - Highlights: • The RGO/PANI/Cu{sub 2}O composite hydrogel was first synthesized via a facile method. • Photocatalytic performance was studied under UV–vis light. • The ternary composite hydrogel shows unexpected photocatalytic activity. • A possible photocatalysis mechanism was illustrated. - Abstract: In this work, a novel reducing graphene/polyaniline/cuprous oxide (RGO/PANI/Cu{sub 2}O) composite hydrogel with a 3D porous network has been successfully prepared via a one-pot method in the presence of cubic Cu{sub 2}O nanoparticles. The as-synthesized ternary composites hydrogel shows unexpected photocatalytic activity such that Congo red (CR) degradation efficiency can reaches 97.91% in 20 min under UV–vis light irradiation, which is much higher than that of either the single component (Cu{sub 2}O nanoparticles), or two component systems (RGO/Cu{sub 2}O composite hydrogel and PANI/Cu{sub 2}O nanocomposites). Furthermore, the ternary composite hydrogel exhibits high stability and do not show any significant loss after five recycles. Such outstanding photocatalytic activity of the RGO/PANI/Cu{sub 2}O composite hydrogel was ascribed to the high absorption ability of the product for CR and the synergic effect among RGO, PANI and Cu{sub 2}O in photocatalytic process. The product of this work would provide a new sight for the construction of UV–vis light responsive photocatalyst with high performance.

  6. A perfectly aligned 63 helical tubular cuprous bromide single crystal for selective photo-catalysis, luminescence and sensing of nitro-explosives.

    Science.gov (United States)

    Yao, Ru-Xin; Hailili, Reshalaiti; Cui, Xin; Wang, Li; Zhang, Xian-Ming

    2015-02-21

    A perfectly aligned 63 helical tubular cuprous bromide single crystal has been synthesized and characterized, which can selectively decompose negatively charged dyes of Methyl Orange (MO) and Kermes Red (KR), and the photocatalytic efficiency is higher than that of nanosized (∼25 nm) TiO2 and ZnO. The direction and magnitude of the dipole moments as well as the band structure were calculated to reveal high photocatalytic efficiency. Moreover, luminescence studies indicate that the CuBr tube materials show very strong yellowish green emissions in the solid state and emulsion even at room temperature, and exhibit extremely high detection sensitivity towards nitro-explosives via fluorescence quenching. Detectable luminescence responses were observed at a very low concentration of 20 ppm with a high quenching efficiency of 94.90%. The results suggest that they may be promising multifunctional materials for photo-catalysis, luminescence and sensing of nitro-explosives.

  7. Plasma-produced phase-pure cuprous oxide nanowires for methane gas sensing

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Qijin, E-mail: ijin.cheng@xmu.edu.cn; Zhang, Fengyan [School of Energy Research, Xiamen University, Xiamen City, Fujian Province 361005 (China); Yan, Wei [School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales 2052 (Australia); Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Randeniya, Lakshman [Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Ostrikov, Kostya [Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Plasma Nanoscience, School of Physics, The University of Sydney, Sydney, New South Wales 2006 (Australia)

    2014-03-28

    Phase-selective synthesis of copper oxide nanowires is warranted by several applications, yet it remains challenging because of the narrow windows of the suitable temperature and precursor gas composition in thermal processes. Here, we report on the room-temperature synthesis of small-diameter, large-area, uniform, and phase-pure Cu{sub 2}O nanowires by exposing copper films to a custom-designed low-pressure, thermally non-equilibrium, high-density (typically, the electron number density is in the range of 10{sup 11}–10{sup 13} cm{sup −3}) inductively coupled plasmas. The mechanism of the plasma-enabled phase selectivity is proposed. The gas sensors based on the synthesized Cu{sub 2}O nanowires feature fast response and recovery for the low-temperature (∼140 °C) detection of methane gas in comparison with polycrystalline Cu{sub 2}O thin film-based gas sensors. Specifically, at a methane concentration of 4%, the response and the recovery times of the Cu{sub 2}O nanowire-based gas sensors are 125 and 147 s, respectively. The Cu{sub 2}O nanowire-based gas sensors have a potential for applications in the environmental monitoring, chemical industry, mining industry, and several other emerging areas.

  8. Characterizations of Cuprous Oxide Thin Films Prepared by Sol-Gel Spin Coating Technique with Different Additives for the Photoelectrochemical Solar Cell

    Directory of Open Access Journals (Sweden)

    D. S. C. Halin

    2014-01-01

    Full Text Available Cuprous oxide (Cu2O thin films were deposited onto indium tin oxide (ITO coated glass substrate by sol-gel spin coating technique using different additives, namely, polyethylene glycol and ethylene glycol. It was found that the organic additives added had a significant influence on the formation of Cu2O films and lead to different microstructures and optical properties. The films were characterized by X-ray diffraction (XRD, field emission scanning electron microscopy (FESEM, and ultraviolet-visible spectroscopy (UV-Vis. Based on the FESEM micrographs, the grain size of film prepared using polyethylene glycol additive has smaller grains of about 83 nm with irregular shapes. The highest optical absorbance film was obtained by the addition of polyethylene glycol. The Cu2O thin films were used as a working electrode in the application of photoelectrochemical solar cell (PESC.

  9. Cupric and cuprous oxide by reactive ion beam sputter deposition and the photosensing properties of cupric oxide metal–semiconductor–metal Schottky photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Min-Jyun; Lin, Yong-Chen; Chao, Liang-Chiun, E-mail: lcchao@mail.ntust.edu.tw; Lin, Pao-Hung; Huang, Bohr-Ran

    2015-08-15

    Highlights: • CuO and Cu{sub 2}O were deposited by reactive ion beam sputter deposition. • Single phase CuO thin film is obtained with Ar:O{sub 2} = 2:1. • CuO MSM PD shows photoresponse from 400 nm to 1.30 μm. • CuO MSM PD is RC limited with a decay time less than 1 μs. - Abstract: Cupric (CuO) and cuprous (Cu{sub 2}O) oxide thin films have been deposited by reactive ion beam sputter deposition at 400 °C with an Ar:O{sub 2} ratio from 2:1 to 12:1. With an Ar:O{sub 2} ratio of 2:1, single phase polycrystalline CuO thin films were obtained. Decreasing oxygen flow rate results in CuO + Cu{sub 2}O and Cu{sub 2}O + Cu mixed thin films. As Ar:O{sub 2} ratio reaches 12:1, Cu{sub 2}O nanorods with diameter of 250 nm and length longer than 1 μm were found across the sample. Single phase CuO thin film exhibits an indirect band gap of 1.3 eV with a smooth surface morphology. CuO metal–semiconductor–metal (MSM) Schottky photodiodes (PD) were fabricated by depositing Cu interdigitated electrodes on CuO thin films. Photosensing properties of the CuO PD were characterized from 350 to 1300 nm and a maximum responsivity of 43 mA/W was found at λ = 700 nm. The MSM PD is RC limited with a decay time constant less than 1 μs.

  10. Literature review on the properties of cuprous oxide Cu{sub 2}O and the process of copper oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Korzhavyi, P. A.; Johansson, B. (Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm (Sweden))

    2011-10-15

    The purpose of the present review is to provide a reference guide to the most recent data on the properties of copper(I) oxide as well as on the atomic processes involved in the initial stages of oxidation of copper. The data on the structure of surfaces, as obtained from atomic-resolution microscopy studies (for example, STM) or from first-principles calculations, are reviewed. Information of this kind may be useful for understanding the atomic mechanisms of corrosion and stress-corrosion cracking of copper

  11. Constructing heterostructure on highly roughened caterpillar-like gold nanotubes with cuprous oxide grains for ultrasensitive and stable nonenzymatic glucose sensor.

    Science.gov (United States)

    Chen, Anran; Ding, Yu; Yang, Zhimao; Yang, Shengchun

    2015-12-15

    In this study, a metal-metal oxide heterostructure was designed and constructed by growing cuprous oxide (Cu2O) grains on highly surface roughened caterpillar-like Au nanotubes (CLGNs) for ultrasensitive, selective and stable nonenzymatic glucose biosensors. The Cu2O grains are tightly anchored to the surface of CLGNs by the spines, resulting in a large increase in the contact area between Cu2O grains and the CLGNs, which facilitates the electron transport between metal and metal oxide and improves the sensitivity and stability of the sensors. The electron transfer coefficient (α) and electron transfer rate constant (ks) for redox reaction of Cu2O-CLGNs/GCE are found to be 0.50114 and 3.24±0.1 s(-1), respectively. The biosensor shows a linear response to glucose over a concentration range of 0.1-5mM and a high sensitivity of 1215.7 µA mM(-1) cm(-2) with a detection limit of 1.83 μM. Furthermore, the Cu2O-CLGNs biosensor exhibited strong anti-interference capability against uric acid (UA), ascorbic acid (AA), potassium chloride (KCl) and sodium ascorbate (SA), as well as a high stability and repeatability. Our current research indicates that the Cu2O-CLGNs hybrid electrode is a promising choice for constructing nonenzyme based electrochemical biosensors.

  12. Multilayer core-shell structured composite paper electrode consisting of copper, cuprous oxide and graphite assembled on cellulose fibers for asymmetric supercapacitors

    Science.gov (United States)

    Wan, Caichao; Jiao, Yue; Li, Jian

    2017-09-01

    An easily-operated and inexpensive strategy (pencil-drawing-electrodeposition-electro-oxidation) is proposed to synthesize a novel class of multilayer core-shell structured composite paper electrode, which consists of copper, cuprous oxide and graphite assembled on cellulose fibers. This interesting electrode structure plays a pivotal role in providing more active sites for electrochemical reactions, facilitating ion and electron transport and shorting their diffusion pathways. This electrode demonstrates excellent electrochemical properties with a high specific capacitance of 601 F g-1 at 2 A g-1 and retains 83% of this capacitance when operated at an ultrahigh current density of 100 A g-1. In addition, a high energy density of 13.4 W h kg-1 at the power density of 0.40 kW kg-1 and a favorable cycling stability (95.3%, 8000 cycles) were achieved for this electrode. When this electrode was assembled into an asymmetric supercapacitor with carbon paper as negative electrode, the device displays remarkable electrochemical performances with a large areal capacitances (122 mF cm-2 at 1 mA cm-2), high areal energy density (10.8 μW h cm-2 at 402.5 μW cm-2) and outstanding cycling stability (91.5%, 5000 cycles). These results unveil the potential of this composite electrode as a high-performance electrode material for supercapacitors.

  13. Physico-chemical studies of cuprous oxide (Cu{sub 2}O) nanoparticles coated on amorphous carbon nanotubes (α-CNTs)

    Energy Technology Data Exchange (ETDEWEB)

    Johan, Mohd Rafie, E-mail: mrafiej@um.edu.my; Meriam Suhaimy, Syazwan Hanani; Yusof, Yusliza, E-mail: yus_liza@siswa.um.edu.my

    2014-01-15

    Amorphous carbon nanotubes (α-CNTs) were synthesized by a chemical reaction between ferrocene and ammonium chloride at a temperature (∼250 °C) in an air furnace. As- synthesized α-CNTs were purified with deionized water and hydrochloric acid. A purified α-CNTs were hybridized with cuprous oxide nanoparticles (Cu{sub 2}O) through a simple chemical process. Morphology of the samples was analyzed with field emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM). Fourier transform infrared (FTIR) spectra showed the attachment of acidic functional groups onto the surface of α-CNTs and the formation of hybridized α-CNTs-Cu{sub 2}O. Raman spectra reveal the amorphous nature of the carbon. X-ray diffraction (XRD) pattern confirmed the amorphous phase of the carbon and the formation of Cu{sub 2}O crystalline phase. The coating of Cu{sub 2}O was confirmed by FESEM, TEM, and XRD. Optical absorption of the samples has also been investigated and the quantum confinement effect was illustrated in the absorption spectra.

  14. Photocatalytic Degradation of Rhodamine B by Cuprous Oxide%氧化亚铜光催化降解罗丹明 B

    Institute of Scientific and Technical Information of China (English)

    黄涛; 吕重安; 杨水金

    2014-01-01

    Cuprous oxide ( Cu2 O) was successfully prepared by the method of reduction in aqueous at room temperature.All the powders were characterized by X -rays diffraction ( XRD) and scanning electron microscopy ( SEM) .The effect of different factors on the degradation was investigated .The best reaction conditions were found out.The photocatalytic degradation of rhodamine B by Cu 2 O under simulated natural light irradiation was investiga-ted.The results demonstrated that initial concentration of rhodamine B is 10 mg/L, catalyst dosage is 0.38 g/L and the pH is 5.2, the degradation ratio of rhodamine B is as high as 96.5%after 30 minutes simulated natural light ir-radiation .%利用室温液相还原法制备了氧化亚铜,通过XRD、 SEM对其进行了表征,探讨了该催化剂对罗丹明B的光催化降解的活性。在催化剂用量为0.38 g/L,过氧化氢量为1.8 mL,罗丹明B的浓度为10 mg/L, pH为5.2的条件下,光照30 min后罗丹明B的降解率为96.5%。

  15. 21 CFR 184.1265 - Cuprous iodide.

    Science.gov (United States)

    2010-04-01

    ... with potassium iodide under slightly acidic conditions. (b) The ingredient must be of a purity suitable... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Cuprous iodide. 184.1265 Section 184.1265 Food and... Substances Affirmed as GRAS § 184.1265 Cuprous iodide. (a) Cuprous iodide (copper (I) iodide, CuI, CAS...

  16. Preparation and Instability of Nanocrystalline Cuprous Nitride.

    Science.gov (United States)

    Reichert, Malinda D; White, Miles A; Thompson, Michelle J; Miller, Gordon J; Vela, Javier

    2015-07-06

    Low-dimensional cuprous nitride (Cu3N) was synthesized by nitridation (ammonolysis) of cuprous oxide (Cu2O) nanocrystals using either ammonia (NH3) or urea (H2NCONH2) as the nitrogen source. The resulting nanocrystalline Cu3N spontaneously decomposes to nanocrystalline CuO in the presence of both water and oxygen from air at room temperature. Ammonia was produced in 60% chemical yield during Cu3N decomposition, as measured using the colorimetric indophenol method. Because Cu3N decomposition requires H2O and produces substoichiometric amounts of NH3, we conclude that this reaction proceeds through a complex stoichiometry that involves the concomitant release of both N2 and NH3. This is a thermodynamically unfavorable outcome, strongly indicating that H2O (and thus NH3 production) facilitate the kinetics of the reaction by lowering the energy barrier for Cu3N decomposition. The three different Cu2O, Cu3N, and CuO nanocrystalline phases were characterized by a combination of optical absorption, powder X-ray diffraction, transmission electron microscopy, and electronic density of states obtained from electronic structure calculations on the bulk solids. The relative ease of interconversion between these interesting and inexpensive materials bears possible implications for catalytic and optoelectronic applications.

  17. A facile one-pot oxidation-assisted dealloying protocol to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks for photodegradation of methyl orange

    Science.gov (United States)

    Liu, Wenbo; Chen, Long; Dong, Xin; Yan, Jiazhen; Li, Ning; Shi, Sanqiang; Zhang, Shichao

    2016-11-01

    In this report, a facile and effective one-pot oxidation-assisted dealloying protocol has been developed to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks (C-S NPC@Cu2O NNs) by chemical dealloying of melt-spun Al 37 at.% Cu alloy in an oxygen-rich alkaline solution at room temperature, which possesses superior photocatalytic activity towards photodegradation of methyl orange (MO). The experimental results show that the as-prepared nanocomposite exhibits an open, bicontinuous interpenetrating ligament-pore structure with length scales of 20 ± 5 nm, in which the ligaments comprising Cu and Cu2O are typical of core-shell architecture with uniform shell thickness of ca. 3.5 nm. The photodegradation experiments of C-S NPC@Cu2O NNs show their superior photocatalytic activities for the MO degradation under visible light irradiation with degradation rate as high as 6.67 mg min-1 gcat-1, which is a diffusion-controlled kinetic process in essence in light of the good linear correlation between photodegradation ratio and square root of irradiation time. The excellent photocatalytic activity can be ascribed to the synergistic effects between unique core-shell architecture and 3D nanoporous network with high specific surface area and fast mass transfer channel, indicating that the C-S NPC@Cu2O NNs will be a promising candidate for photocatalysts of MO degradation.

  18. Sensitivity of cuprous azide towards heat and impact

    Directory of Open Access Journals (Sweden)

    Kartar Singh

    1958-07-01

    Full Text Available "Rates of thermal decomposition of azide at six different temperatures have been measured. The sigmoid shapes of the curves representing increase in pressure with time suggest that a given temperature a fixed number of nuclei are formed at the end of the induction period. The nuclei increase in size in three dimensions. The radius of any nucleus at any instant (tis directly proportional to (t-t/Sub/owhere t/Sub/o is the induction period. The activation energy involved in thermal has been found decomposition to be 26.5K calories. It is suggested that this activation energy corresponds to the energy required for thermal transition of an electron 3 d band to the Fermi level of the metallic copper nuclei. The impact sensitivity and induction period necessary for explosion at various temperatures for crystalline and precipitated samples of cuprous azide have been measured. The results indicate that cuprous azide is more sensitive towards heat and impact than lead azide. The impact sensitivity of cuprous azide is found to increase in crystal size."

  19. 氧化锌/氧化亚铜异质结太阳能电池的研究进展∗%Research Progress in Zinc Oxide/Cuprous Oxide Heterojunction Solar Cell

    Institute of Scientific and Technical Information of China (English)

    冯云珠; 董磊; 于良民

    2015-01-01

    Much attention recently has been paid on p-n heterojunction solar cells fabricated with cuprous oxide combined with zinc oxide owing to the advantage of favorable alignment of conductive band edges and lattice matching. The formation of heterojunctions can enhance the seperation of photoinduced electrons and holes,as well as the absor-bance of the light.This review compiles the main milestones reached during the last decades in the development of ZnO/Cu2 O heterojunction solar cells comprehensively.Different junction structures of these cells as planar and ZnO nanoarray based ones related to deposition sequences and synthesis methods are introduced separately,while photovol-taic property influence factors as well as improving methods are discussed.Considering the accomplishments achieved in a relatively short period of time,it can be said that this kind of solar cell can be promisingly applied in clean energy exploitation in the future,in spite of improvement of cell performance still in need.%因氧化亚铜(Cu2 O)、氧化锌(ZnO)能级和晶格匹配较好,近年来较多的研究者将两者复合制备异质结太阳能电池。异质结的形成可提高光生电子-空穴对的分离效率,同时拓展复合结构的光响应范围,从而有效提高太阳能电池性能。介绍了3类主流的 ZnO/Cu2 O 异质结结构,分别阐述主要的进展,综述了异质结结构中 Cu2 O、ZnO的制备方法以及制备条件对电池效率的影响,讨论了电池性能的改进措施,并对 ZnO/Cu2 O 异质结太阳能电池未来的发展前景进行展望。

  20. Restored thermoluminescence in oxide crystals

    Energy Technology Data Exchange (ETDEWEB)

    Rakov, A.F., E-mail: afrakov@hotmail.co [Institute of Nuclear Physics, Uzbek Academy of Sciences, Tashkent, 700132 (Uzbekistan); Salikhbaev, U.S.; Islamov, A.K. [Institute of Nuclear Physics, Uzbek Academy of Sciences, Tashkent, 700132 (Uzbekistan); Bartram, R.H. [Department of Physics, University of Connecticut, Storrs, CT 06269-3046 (United States); Melcher, C.L. [Scintillation Materials Research Center, University of Tennessee, Knoxville, TN 37996-2000 (United States)

    2010-11-15

    In this paper, we present the results of a thermoluminescence study on several oxide crystals, including Y{sub 3}Al{sub 5}O{sub 12} (YAG), Y{sub 3}Al{sub 5}O{sub 12}:Nd (YAG:Nd), Lu{sub 2}SiO{sub 5}:Ce (LSO:Ce), Y{sub 2}SiO{sub 5}:Ce (YSO:Ce), Gd{sub 2}SiO{sub 5}:Ce (GSO:Ce), PbWO (PWO), and PbWO:La (PWO:La). A phenomenon involving restoration of thermoluminescence (TL) glow peaks is found to occur in some of the crystals investigated; crystals {gamma}-irradiated at room temperature and subsequently stored for some time in the dark at 77 K exhibit TL glow peaks in the range below room temperature. This phenomenon is caused not by a thermally or optically stimulated process, but rather as a by-product of a tunneling process. The intensity of the restored TL glow peaks measured in LSO:Ce crystals is found to be proportional both to the radiation dose and to the storage-time at low temperature. A phenomenological theoretical model is proposed, in which tunneling recombination occurs between deep electron and hole traps accompanied by the simultaneous ejection of an electron to the conduction band; some of these conduction electrons then repopulate shallow traps. An oxygen vacancy with two trapped electrons is assumed to be the deep electron trap in this model. The role of oxygen vacancies is confirmed by heating in air at 1000 {sup o}C. This model is applied specifically to LSO:Ce, and several possible candidates are suggested for shallow traps in that material.

  1. Controlling the Formation of Nanocavities in Kirkendall Nanoobjects through Sequential Thermal Ex Situ Oxidation and In Situ Reduction Reactions.

    Science.gov (United States)

    Mel, Abdel-Aziz El; Tessier, Pierre-Yves; Buffiere, Marie; Gautron, Eric; Ding, JunJun; Du, Ke; Choi, Chang-Hwan; Konstantinidis, Stephanos; Snyders, Rony; Bittencourt, Carla; Molina-Luna, Leopoldo

    2016-06-01

    Controlling the porosity, the shape, and the morphology of Kirkendall hollow nanostructures is the key factor to tune the properties of these tailor-made nanomaterials which allow in turn broadening their applications. It is shown that by applying a continuous oxidation to copper nanowires following a temperature ramp protocol, one can synthesize cuprous oxide nanotubes containing periodic copper nanoparticles. A further oxidation of such nanoobjects allows obtaining cupric oxide nanotubes with a bamboo-like structure. On the other hand, by applying a sequential oxidation and reduction reactions to copper nanowires, one can synthesize hollow nanoobjects with complex shapes and morphologies that cannot be obtained using the Kirkendall effect alone, such as necklace-like cuprous oxide nanotubes, periodic solid copper nanoparticles or hollow cuprous oxide nanospheres interconnected with single crystal cuprous oxide nanorods, and aligned and periodic hollow nanospheres embedded in a cuprous oxide nanotube. The strategy demonstrated in this study opens new avenues for the engineering of hollow nanostructures with potential applications in gas sensing, catalysis, and energy storage.

  2. Preparation of poly(butyl methacrylate-co-ethyleneglyceldimethacrylate) monolithic column modified with β-cyclodextrin and nano-cuprous oxide and its application in polymer monolithic microextraction of polychlorinated biphenyls.

    Science.gov (United States)

    Zheng, Haijiao; Liu, Qingwen; Jia, Qiong

    2014-05-23

    A poly(butyl methacrylate-co-ethyleneglyceldimethacrylate) (poly(BMA-EDMA)) monolithic column was prepared with in situ polymerization method and modified with allylamine-β-cyclodextrin (ALA-β-CD) and nano-cuprous oxide (Cu2O). A polymer monolith microextraction method was developed with the modified monolithic column for the preconcentration of polychlorinated biphenyls combined with gas chromatography-electron capture detector. Various parameters affecting the extraction efficiency were investigated and optimized. Under the optimum experimental conditions, we obtained acceptable linearities, low limits of detection, and good intra-day/inter-day relative standard deviations. Because of the hydrophobic properties of β-CD and the porous nano structure of Cu2O, the enrichment capacity of the poly(BMA-EDMA) monolithic column was significantly improved. The extraction efficiency followed the order: poly(BMA-EDMA-ALA-β-CD-Cu2O)>poly(BMA-EDMA-ALA-β-CD)>poly(BMA-EDMA)>direct GC analysis. When applied to the determination of polychlorinated biphenyls in wine samples, low limits of detection (0.09ngmL(-1)) were obtained under the preoptimized conditions (sample volume 1.0mL, sample flow rate 0.1mLmin(-1), eluent volume 0.1mL, and eluent flow rate 0.05mLmin(-1)). In addition, the present method was employed to determine polychlorinated biphenyls in red wine samples and the accuracy was assessed through recovery experiments. The obtained recovery values were in the range of 78.8-104.1% with relative standard deviations less than 9.0%.

  3. Synthesis and Characterization of Cu2O Single-Crystal by Sonochemical Method%氧化亚铜单晶的声化学制备及表征

    Institute of Scientific and Technical Information of China (English)

    张霞; 陶小军; 张治军; 吴志申; 张平余

    2005-01-01

    Cuprous oxide single crystal has been synthesized by sonochemical method through the thermal decomposition of copper acetate monohydrate in paraffin oil. TEM, XRD, SEM, ED and XPS techniques have been used to characterize its morphology, structure and composition. It is found that when the temperature is increased,decomposition from Cu2O to Cu takes place.

  4. Effects of lithium (Li) on lithium-cuprous-oxide (Li-Cu2O) composite films grown by using electrochemical deposition for a PEC photoelectrode

    Science.gov (United States)

    Kim, Tae Gyoum; Ryu, Hyukhyun; Lee, Won-Jae

    2016-01-01

    In this study, Li-Cu2O composite films were grown on fluorine-doped tin-oxide (FTO) substrates by using the electrochemical deposition method. Various amounts of lithium (Li) were added to grow the Li-Cu2O composite films. We analyzed the morphology, structure, photocurrent density and photo-stability of the Li-Cu2O composite films by using various measurements such as field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and potentiostat/galvanostat measurements, respectively. As a result, the highest XRD Cu2O (111)/ LiO (011) peak intensity ratio was obtained for the 10-wt% sample, which also had the highest photocurrent density value of -5.00 mA/cm2. The highest photocurrent density value for the 10-wt% sample was approximately 5 times greater than that of the 0-wt% sample. As shown by this result, we found that adding Li could improve the photocurrent values of Li-Cu2O composite films.

  5. Preparation of Cystein from Cysteine Cuprous Mercaptide%由半胱氨酸亚铜制取半胱氨酸

    Institute of Scientific and Technical Information of China (English)

    刘勋; 胡敏; 姚小平

    2015-01-01

    In this paper ,a new preparation method of cysteine hydrochloride monohydrate from cysteine cu‐prous mcercaptide ,which is prepared by the reduction and precipitation of cystine with cuprous oxide has been introduced ,including re‐precipitation of cysteine cuprous mercaptide ,removal of copper using H2 S , decoloration ,crystallization and recrystalization .The yield of the product is up to 12 .4% ,with the quality according with the Japanese AJI standards .%研究了一种用氧化亚铜将胱氨酸还原沉淀为半胱氨酸亚铜,再由此制备半胱氨酸盐酸盐一水物的新方法.该方法包含半胱氨酸亚铜再沉淀,H2 S法脱铜,脱色,产品结晶,重结晶等步骤,半胱氨酸盐酸盐一水物收率达12.4%,产品质量符合日本味之素标准.

  6. INTERFACIAL MASS TRANSPORT IN OXIDE CRYSTAL GROWTH

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ A space high temperature in situobservation instrument (SHITISOI) is dedicated to visualize and record the whole growth process of oxide crystal in high temperature melts and solutions. Model experiments using transparent liquids such as KNbO3,Li2B4O7+KNbO3 were chosen to investigate effects of interracial mass transport in oxide crystal growth. For the scaling of the coupled velocity, heat and concentration fields in KNbO3 crystal growth, a rotating crystal growth process was performed and the widths of interfacial concentration, heat and momentum transition zones (The "boundary layers") are obtained, which are 7.5×10-a, 8.6×10-2 and 4.4×10-1 cm,respectively. Hence one can expect that interfacial concentration gradient will be confined to a narrow layer and in region of major concentration change at the in terface. In order to study a mechanism based on the interfacial mass transport resulting from hydrodynamics, the growth of KNbO3 grain in high temperature Li2B4O7 and KNbO3 solutin was studied. The result shows that the pivotal feature in the KNbO3 crystal growth is the initiated by KNbO3 solute surface tension gra dient which is caused by the slow diffusion of KNbO3 solutes. Direct comparison of the model predictions and experimental observed phenomena demonstrate the predictive capability of this model.

  7. Memristive Properties of Thin Film Cuprous Oxide

    Science.gov (United States)

    2011-03-01

    Banerjee and D Chakravorty, "Optical absorption by nanoparticles of Cu2O," Europhysics Letters , vol. 52, no. 4, pp. 468-473, November 2000. [20] Gunter...Kotsugi, "Inhomogeneous chemical states in resistance-switching devices with a planar-type Pt/CuO/Pt structure," Applied Physics Letters , vol. 95, p...11] R Dong et al., "Reproducible hysteresis and resistive switching in metal-CuxO- metal," Applied Physics Letters , vol. 90, p. 042107, 2007. [12

  8. The fictile coordination chemistry of cuprous-thiolate sites in copper chaperones.

    Science.gov (United States)

    Pushie, M Jake; Zhang, Limei; Pickering, Ingrid J; George, Graham N

    2012-06-01

    Copper plays vital roles in the active sites of cytochrome oxidase and in several other enzymes essential for human health. Copper is also highly toxic when dysregulated; because of this an elaborate array of accessory proteins have evolved which act as intracellular carriers or chaperones for the copper ions. In most cases chaperones transport cuprous copper. This review discusses some of the chemistry of these copper sites, with a view to some of the structural factors in copper coordination which are important in the biological function of these chaperones. The coordination chemistry and accessible geometries of the cuprous oxidation state are remarkably plastic and we discuss how this may relate to biological function. This article is part of a Special Issue entitled: Biogenesis/Assembly of Respiratory Enzyme Complexes.

  9. Oxidation and crystal field effects in uranium

    Energy Technology Data Exchange (ETDEWEB)

    Tobin, J. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Booth, C. H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Shuh, D. K. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); van der Laan, G. [Diamond Light Source, Didcot (United Kingdom); Sokaras, D. [Stanford Synchrotron Radiation Lightsource, Stanford, CA (United States); Weng, T. -C. [Stanford Synchrotron Radiation Lightsource, Stanford, CA (United States); Yu, S. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bagus, P. S. [Univ. of North Texas, Denton, TX (United States); Tyliszczak, T. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Nordlund, D. [Stanford Synchrotron Radiation Lightsource, Stanford, CA (United States)

    2015-07-06

    An extensive investigation of oxidation in uranium has been pursued. This includes the utilization of soft x-ray absorption spectroscopy, hard x-ray absorption near-edge structure, resonant (hard) x-ray emission spectroscopy, cluster calculations, and a branching ratio analysis founded on atomic theory. The samples utilized were uranium dioxide (UO2), uranium trioxide (UO3), and uranium tetrafluoride (UF4). As a result, a discussion of the role of non-spherical perturbations, i.e., crystal or ligand field effects, will be presented.

  10. Cobalt oxides from crystal chemistry to physics

    CERN Document Server

    Raveau, Bernard

    2012-01-01

    Unparalleled in the breadth and depth of its coverage of all important aspects, this book systematically treats the electronic and magnetic properties of stoichiometric and non-stoichiometric cobaltites in both ordered and disordered phases. Authored by a pioneer and a rising star in the field, the monograph summarizes, organizes and streamlines the otherwise difficult-to-obtain information on this topic. An introductory chapter sets forth the crystal chemistry of cobalt oxides to lay the groundwork for an understanding of the complex phenomena observed in this materials class. Special emphasis is placed on a comprehensive discussion of cobaltite physical properties in different structural families. Providing a thorough introduction to cobalt oxides from a chemical and physical viewpoint as a basis for understanding their intricacies, this is a must-have for both experienced researchers as well as entrants to the field.

  11. Crystal-free Formation of Non-Oxide Optical Fiber

    Science.gov (United States)

    Nabors, Sammy A.

    2015-01-01

    Researchers at NASA Marshall Space Flight Center have devised a method for the creation of crystal-free nonoxide optical fiber preforms. Non-oxide fiber optics are extensively used in infrared transmitting applications such as communication systems, chemical sensors, and laser fiber guides for cutting, welding and medical surgery. However, some of these glasses are very susceptible to crystallization. Even small crystals can lead to light scatter and a high attenuation coefficient, limiting their usefulness. NASA has developed a new method of non-oxide fiber formation that uses axial magnetic fields to suppress crystallization. The resulting non-oxide fibers are crystal free and have lower signal attenuation rates than silica based optical fibers.

  12. Complex oxides: Creative tension in layered crystals

    Science.gov (United States)

    Gopalan, Venkatraman; Engel-Herbert, Roman

    2016-09-01

    New findings suggest that the mechanical stretching of layered crystals can transform them from a polar to a nonpolar state. This could spur the design of multifunctional materials controlled by an electric field.

  13. Twin domains in nickel-oxide type crystals

    Science.gov (United States)

    Mandel, V. S.

    1997-04-01

    NiO-type antiferromagnets, 2-valent oxides of 3d transition metals: MnO, CoO and NiO, are isomorphic in the paramagnetic state. They have a face-centered cubic lattice. Below the Neel temperature TN, magnetic ordering in these crystals is accompanied by a distortion of the cubic lattice. Although this distortion is very slight, it reduces the crystal symmetry. Because the cubic crystal has several equivalent directions which can become distortion axes, below TN the crystal undergoes twinning, splitting up into several macroscopic regions known as T-domains. Crystals were grown by three methods: Verneuil, epitaxy from the gas phase, and flux-melt growth. They were investigated via polarization microscopy, X-ray topography and antiferromagnetic resonance. The use of a variety of growth methods and investigating techniques made it possible to obtain reliable information about the structure of NiO-type crystals.

  14. Synthesis, crystal growth and mechanical properties of Bismuth Silicon Oxide (BSO) single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Riscob, B. [CSIR – National Physical Laboratory, Crystal Growth and X-ray Analysis, New Delhi 110 012 (India); Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat (India); Shkir, Mohd. [CSIR – National Physical Laboratory, Crystal Growth and X-ray Analysis, New Delhi 110 012 (India); Ganesh, V. [Department of Physics, Kakatiya University, Warangal 506 009 (India); Vijayan, N.; Maurya, K.K. [CSIR – National Physical Laboratory, Crystal Growth and X-ray Analysis, New Delhi 110 012 (India); Kishan Rao, K. [Department of Physics, Kakatiya University, Warangal 506 009 (India); Bhagavannarayana, G., E-mail: bhagavan@mail.nplindia.ernet.in [CSIR – National Physical Laboratory, Crystal Growth and X-ray Analysis, New Delhi 110 012 (India)

    2014-03-05

    Highlights: • Synthesis of Bismuth Silicon Oxide (BSO). • Single crystal growth of BSO by Czochralski (Cz) method. • Complete mechanical analysis by device fabrication point of view. • Theoretical and experimental calculations of mechanical properties. -- Abstract: Bismuth Silicon Oxide (BSO) is an efficient material for piezo-electric and electro-optic applications. In this article, growth of BSO single crystal by high temperature Czochralski melt growth technique and its detailed mechanical characterization by Vickers microhardness, fracture toughness, crack propagation, brittleness index and yield strength have been reported. The raw material was synthesized by solid state reaction using the stoichiometric ratio of high purity bismuth tri-oxide and silicon di-oxide. The synthesized material was charged in the platinum crucible and then melted. The required rotation and pulling rate was optimized for BSO single crystal growth and good quality single crystal has been harvested after a time span of 5 days. Powder X-ray diffraction analysis confirms the parent crystallization phase of BSO. The experimentally studied mechanical behavior of the crystal is explained using various theoretical models. The anisotropic nature of the crystals is studied using Knoop indentation technique.

  15. Spectral properties of oxide crystals free of iron ions

    Energy Technology Data Exchange (ETDEWEB)

    Kvapil, J.; Perner, B.; Kvapil, J.; Manek, B.; Kubelka, J.; Blazek, K. (Monokrystaly, Turnov (Czechoslovakia)); Austrata, R.; Schauer, P. (Czechoslovak Academy of Sciences, Brno. Inst. of Scientific Instruments); Vitamvas, Z. (Technical Univ., Liberec (Czechoslovakia))

    1982-07-01

    Al/sub 2/O/sub 3/ and YAG crystals were purified from traces of iron by the growth in reducing atmosphere. Luminescence output of such materials was substantially increased, but some undesirable properties as transient colour centre formation in YAG:Nd and low damage threshold of ruby laser rods were observed. Minimum concentration of iron ions which drastically change spectral properties of oxide crystals seems to be

  16. Thermo-electric oxidization of iron in lithium niobate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Falk, Matthias

    2007-07-01

    Lithium niobate crystals (LiNbO{sub 3}) are a promising material for nonlinear-optical applications like frequency conversion to generate visible light, e.g., in laser displays, but their achievable output power is greatly limited by the ''optical damage'', i.e., light-induced refractive-index changes caused by excitation of electrons from iron impurities and the subsequent retrapping in unilluminated areas of the crystal. The resulting space-charge fields modify the refractive indices due to the electro-optic effect. By this ''photorefractive effect'' the phase-matching condition, i.e., the avoidance of destructive interference between light generated at different crystal positions due to the dispersion of the fundamental wave and the converted wave, is disturbed critically above a certain light intensity threshold. The influence of annealing treatments conducted in the presence of an externally applied electric field (''thermo-electric oxidization'') on the valence state of iron impurities and thereby on the optical damage is investigated. It is observed that for highly iron-doped LiNbO{sub 3} crystals this treatment leads to a nearly complete oxidization from Fe{sup 2+} to Fe{sup 3+} indicated by the disappearance of the absorption caused by Fe{sup 2+}. During the treatment an absorption front forms that moves through the crystal. The absorption in the visible as well as the electrical conductivity are decreased by up to five orders of magnitude due to this novel treatment. The ratio of the Fe{sup 2+} concentration to the total iron concentration - a measure for the strength of the oxidization - is in the order of 10{sup -6} for oxidized crystals whereas it is about 10{sup -1} for untreated samples. Birefringence changes are observed at the absorption front that are explained by the removal of hydrogen and lithium ions from the crystal that compensate for the charges of the also removed electrons from

  17. Chemical Bond Analysis of Single Crystal Growth of Magnesium Oxide

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Starting from the crystallographic structure of magnesium oxide (MgO), both the chemical bond model of solids and Pauling's third rule (polyhedral sharing rule) were employed to quantitatively analyze the chemical bonding structure of constituent atoms and single crystal growth. Our analytical results show that MgO single crystals prefer to grow along the direction and the growth rate of the {100} plane is the slowest one. Therefore, the results show that the {100} plane of MgO crystals can be the ultimate morphology face, which is in a good agreement with our previous experimental results. The study indicate that the structure analysis is an effective tool to control the single-crystal growth.

  18. Platinum single crystal electrodes for the electrocatalysis of methane oxidation

    Directory of Open Access Journals (Sweden)

    Mayara Munaretto

    2011-03-01

    Full Text Available The main objective of this paper is to characterize the voltammetric profiles of platinum single crystals of low Miller indexes Pt(100 and Pt(110 and study their catalytic activities on the oxidation of methane. In this way, it was developed a metallic surface modified by presence of other metal oxide, which presents catalytic activity for this reaction. It is well known that the electrooxidation of methane (CH4 leads mainly to the formation of CO2 and H2O, however, the oxidation can also lead to the formation of CO, a reaction intermediate that has strong interaction with metal surfaces, such as platinum. This molecule tends to accumulate on the platinum surface and to passive it, due to the self-poisoning, decreasing its catalytic activity. Therefore, the main aim of this work was the development of a platinum electrode modified by deposition of titanium oxide, which presented electrocatalytic properties for the oxidation of methane.

  19. Single crystal to single crystal transformation and hydrogen-atom transfer upon oxidation of a cerium coordination compound.

    Science.gov (United States)

    Williams, Ursula J; Mahoney, Brian D; Lewis, Andrew J; DeGregorio, Patrick T; Carroll, Patrick J; Schelter, Eric J

    2013-04-15

    Trivalent and tetravalent cerium compounds of the octamethyltetraazaannulene (H2omtaa) ligand have been synthesized. Electrochemical analysis shows a strong thermodynamic preference for the formal cerium(IV) oxidation state. Oxidation of the cerium(III) congener Ce(Homtaa)(omtaa) occurs by hydrogen-atom transfer that includes a single crystal to single crystal transformation upon exposure to an ambient atmosphere.

  20. Microbial Manganese Oxidation in Saltmarsh Surface Sediments Using a Leuco Crystal Violet Manganese Oxide Detection Technique

    Science.gov (United States)

    Spratt, Henry G.; Siekmann, Ellen C.; Hodson, Robert E.

    1994-01-01

    Microbial manganese (Mn) oxide production in surface sediments of a Georgia saltmarsh was directly measured using an assay involving the oxidation of 4,4',4″-methylidynetris (N,N-dimethylaniline), leuco crystal violet (LCV), by Mn oxides to produce crystal violet. The assay exhibits high specificity for Mn oxides without interference by Mn(II) and is sufficiently sensitive to determine rates of Mn oxidation in surface sediment or saltmarsh creek water suspensions. Sample salinity affects crystal violet absorbance in the 0-25 salinity range and must be corrected for in Mn oxide determinations for estuarine samples of variable salinity. Other oxidants found to oxidize LCV slowly included Cl(I), Cr(III), I(V), Fe(III), and Mn(III), although the sensitivity of the assay for Mn(IV) oxides was found to be seven times greater than for Mn(III), and at least 100 times greater than for any of the other oxidants. Rates of abiotic Mn oxide production in sediment suspensions treated with either sodium azide or formalin, or autoclaved, were much slower than rates determined for untreated sediments. Sodium azide (7·7 mM) inhibited Mn oxide production in these sediment suspensions to rates between 5 and 10% of the rates of Mn oxidation determined for unamended suspensions. Manganese oxidation was highly temperature dependent, with maximal rates on a dry weight basis (8·9 nmol mg dwt -1 h -1), occurring at 60°C, and negligible activity at 100 and 0°C. Rates were also dependent on sample pH, with maximal rates at pH 6·7, decreasing to near 0 as the pH was lowered to approximately 3·0. For Mn(II) concentrations ranging from 9 to 91 μM, rates of Mn oxide production were independent of Mn(II) concentration, while Mn oxide production was inhibited at concentrations greater than 91 μM (e.g. by 25-40% at 450 μM). Rates of microbial Mn oxide production in surface sediment/saltmarsh creek water suspensions incubated under natural conditions of temperature, pH, and Mn

  1. 纳米Cu2O及其复合物的制备及光催化性能研究%Preparation and Photocatalytic Property of Nano Cuprous Oxide and Its Composites

    Institute of Scientific and Technical Information of China (English)

    胥桂萍; 邱黎

    2013-01-01

    Cu2O powders and TiO2-Cu2O composite powders were prepared by chemical deposi-tion method. With prepared Cu2O nanoparticles as photocatalyst,photocatalytic oxidation degrada-tion of methylene blue solution was explored. The effects of dosage of H2O2,the initial concentration of methylene blue and composite samples on the degradation performance were investigated with UV-visible spectrophotometer. The results showed that the degradation efficiency was the best when the amount of H2O2 was 5mL in 30mL methylene blue solution and the initial concentration of methy-lene blue was 10mg/L,and the catalytic efficiency of TiO2-Cu2O composite powders was much high-er than that of Cu2O.%采用化学沉积法制备Cu2O粉体,并且制备了TiO2-Cu2O复合粉体。以制备的纳米Cu2O为光催化剂,对亚甲基蓝溶液进行光催化氧化降解。通过紫外-可见分光光度计考察了H2O2的加入量、亚甲基蓝的初始浓度及复合样品对降解性能的影响。结果表明,当H2O2的用量在5 mL/30 mL,亚甲基蓝的初始浓度为10 mg/L时降解效果最好;复合粉体的催化效率远高于Cu2O的光催化效率。

  2. Oxidation Potential, Not Crystal Structure, Controls the Oxidation State of Iron in Perovskite

    Science.gov (United States)

    Panero, W. R.; Pigott, J. S.; Watson, H. C.; Scharenberg, M.; Green, H. W.; McComb, D. W.; Williams, R. E.

    2013-12-01

    The mantle's oxidation state has broad implications on the state and evolution of the earth's interior. The relatively high oxidation potential of the upper mantle is such that iron is predominantly Fe2+ with small amounts of Fe3+ . Fe3+ is more stable than Fe2+ in the dominant lower mantle mineral, perovskite, despite the fact that the effect of pressure is to reduce the oxidizing potential of a system. It is therefore suggested that iron undergoes a disproportionation reaction of 3Fe2+ =2Fe3+ +Fe0 , controlled by the crystallography instead of oxidation potential. We crystallized synthetic enstatite glass with 5% Al2O3, 14% FeO, and 3% Fe2O3 in the laser-heated diamond anvil cell at 25-63 GPa and 1700-2800 K. We find that for temperatures nm iron precipitates on grain boundaries. The precipitates have small amounts of dissolved oxygen, but are Mg- and Al- free. We interpret that the stishovite is forming due to the oxidation of the ferric iron to ferrous iron according to (Mg2+,Al3+)(Fe3+,Si4+)O3 +SiO2 + Fe0 while the lower-temperature samples crystallizing as approximately (Mg2+ Fe2+ Al3+ )(Fe3+ Al3+ Si4+ )O3. We observe 2.8(2) Å3 volume expansion of the perovskite and a 28(2) GPa decrease in compressibility of the perovskite relative to the perovskite forming at lower temperature, consistent with the proposed compositions of the perovskites. As the increased temperature increases the oxidation potential of the system, we suggest that the oxidation state of iron in perovskite is dependent on oxidation potential as opposed to perovskite's crystal structure. Transmission Electron Microscopy (TEM) coupled with Electron Energy Loss Spectroscopy (EELS) show iron precipitation on grain boundaries supporting the conclusion. We present a discussion of the results and implications for core formation and lower mantle dynamics.

  3. Defect engineering of the electronic transport through cuprous oxide interlayers

    KAUST Repository

    Fadlallah, Mohamed M.

    2016-06-03

    The electronic transport through Au–(Cu2O)n–Au junctions is investigated using first-principles calculations and the nonequilibrium Green’s function method. The effect of varying the thickness (i.e., n) is studied as well as that of point defects and anion substitution. For all Cu2O thicknesses the conductance is more enhanced by bulk-like (in contrast to near-interface) defects, with the exception of O vacancies and Cl substitutional defects. A similar transmission behavior results from Cu deficiency and N substitution, as well as from Cl substitution and N interstitials for thick Cu2O junctions. In agreement with recent experimental observations, it is found that N and Cl doping enhances the conductance. A Frenkel defect, i.e., a superposition of an O interstitial and O substitutional defect, leads to a remarkably high conductance. From the analysis of the defect formation energies, Cu vacancies are found to be particularly stable, in agreement with earlier experimental and theoretical work.

  4. Carbon nanotube-cuprous oxide composite based pressure sensors

    Institute of Scientific and Technical Information of China (English)

    Kh. S. Karimov; Muhammad Tariq Saeed Chani; Fazal Ahmad Khalid; Adam Khan; Rahim Khan

    2012-01-01

    In this paper,we present the design,the fabrication,and the experimental results of carbon nanotube (CNT) and Cu2O composite based pressure sensors.The pressed tablets of the CNT-Cu2O composite are fabricated at a pressure of 353 MPa.The diameters of the multiwalled nanotubes (MWNTs) are between 10 nm and 30 nm.The sizes of the Cu2O micro particles are in the range of 3-4 μrn.The average diameter and the average thickness of the pressed tablets are 10 mm and 4.0 mm,respectively.In order to make low resistance electric contacts,the two sides of the pressed tablet are covered by silver pastes.The direct current resistance of the pressure sensor decreases by 3.3 times as the pressure increases up to 37 kN/m2.The simulation result of the resistance-pressure relationship is in good agreement with the experimental result within a variation of ±2%.

  5. Correlating crystallization and ionic conductivity of PEO/graphene oxide nanocomposite

    Science.gov (United States)

    Cheng, Shan; Smith, Derrick; Hsuan, Grace; Li, Christopher

    2012-02-01

    Polyethylene oxide (PEO) is one of the best candidates for solid state electrolyte due to its chemical stability and strong ability to form complex with lithium salts. Crystallization behavior of PEO directly affects the lithium ion transport, and in turn the ionic conductivity of the electrolyte. By adding two dimensional graphene oxide nanosheets into PEO matrix, mechanical property of the latter is significantly strengthened, while the crystallization behavior of PEO is also altered by the graphene oxide sheets. The crystallization of PEO/graphene oxide nanocomposites was studied by differential scanning calorimetry (DSC) and the orientations of graphene oxide and PEO crystal were studied by small angle X-ray scattering and wide angle X-ray diffraction. PEO/graphene oxide nanocomposite doped with lithium salt was further fabricated and characterized by electrochemical impedance spectroscopy. Anisotropic ionic conductivity was observed for the nanocomposite electrolyte due to the orientation of graphene oxide and directional growth of PEO crystals.

  6. Influence of deuteration and fluorination on the supramolecular architecture of pyridine N-oxide crystals.

    Science.gov (United States)

    Shishkin, Oleg V; Shishkina, Svitlana V; Maleev, Andrey V; Zubatyuk, Roman I; Vasylyeva, Vera; Merz, Klaus

    2013-03-18

    To understand how deuterium and fluorine substituents influence the supramolecular architecture of pyridine N-oxide crystals, the crystal structure of 3-fluoropyridine N-oxide (PNO-3F) was determined and the crystal packing motives of non-deuterated pyridine-N-oxide (PNO), partial-deuterated pyridine-N-oxide (PNO-D) and PNO-3F were analyzed based on ab initio quantum-chemical calculations of the intermolecular interaction energy, using the MP2/6-311G(d,p) method. The appearance of the weak-directing substituents deuterium and fluorine leads to significant changes in the crystal organization of the isotropic packing of PNO molecules.

  7. Thermal oxidation of single crystal aluminum antimonide and materials having the same

    Science.gov (United States)

    Sherohman, John William; Yee, Jick Hong; Coombs, III, Arthur William; Wu, Kuang Jen J.

    2012-12-25

    In one embodiment, a method for forming a non-conductive crystalline oxide layer on an AlSb crystal includes heat treating an AlSb crystal in a partial vacuum atmosphere at a temperature conducive for air adsorbed molecules to desorb, surface molecule groups to decompose, and elemental Sb to evaporate from a surface of the AlSb crystal and exposing the AlSb crystal to an atmosphere comprising oxygen to form a crystalline oxide layer on the surface of the AlSb crystal. In another embodiment, a method for forming a non-conductive crystalline oxide layer on an AlSb crystal includes heat treating an AlSb crystal in a non-oxidizing atmosphere at a temperature conducive for decomposition of an amorphous oxidized surface layer and evaporation of elemental Sb from the AlSb crystal surface and forming stable oxides of Al and Sb from residual surface oxygen to form a crystalline oxide layer on the surface of the AlSb crystal.

  8. The refractive index of zinc oxide microwire single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Czekalla, Christian; Kuehne, Philipp; Sturm, Chris; Schmidt-Grund, Ruediger; Grundmann, Marius [Universitaet Leipzig (Germany). Fakultaet fuer Physik und Geowissenschaften, Institut fuer Experimentelle Physik II

    2010-07-01

    Among a large number of applications, zinc oxide (ZnO) single crystals (bulk and micro- and nanowires) are expected to form important building blocks for future optoelectronic devices like light emitting and laser diodes. Optical resonances from ZnO structures have been observed by a number of groups in the past years. In most of the publications, modeling of the mode structure, especially in the near bandgap spectral region, is difficult because the energy dependent refractive index n(E) is typically not known. Additionally, in case of the self assembled micro- and nanowires, the structures are too small to perform spectroscopic ellipsometry to determine n(E). We compare n(E) obtained from (a) spectroscopic ellipsometry measurements of ZnO bulk single crystals and (b) spatially resolved photoluminescence measurements of ZnO microwires employing a plane wave whispering gallery mode model for the observed resonances. We discuss the differences between the results obtained from the two methods and their mutual impact, leading to a highly precise determination of n(E) in an energy range between 1.80 eV and 3.25 eV and for temperatures between 10 K and 295 K.

  9. Crystal structure of iron-oxide nanoparticles synthesized from ferritin

    Energy Technology Data Exchange (ETDEWEB)

    Krispin, Michael, E-mail: michael.krispin@physik.uni-augsburg.de; Ullrich, Aladin, E-mail: aladin.ullrich@physik.uni-augsburg.de; Horn, Siegfried, E-mail: horn@physik.uni-augsburg.de [University of Augsburg, Institute of Physics (Germany)

    2012-02-15

    We have investigated the crystal structure of nanosized iron-oxide by X-ray diffraction (XRD), extended X-ray absorption fine structure measurements at the iron K-edge as well as by transmission electron microscopy (TEM). Iron-oxide nanoparticles were produced by thermal treatment of horse spleen ferritin molecules. The structure of these particles was compared to {alpha}-Fe{sub 2}O{sub 3} and {gamma}-Fe{sub 2}O{sub 3} nanopowder references. The thermal treatment of a submonolayer film of ferritin molecules results in pure {gamma}-Fe{sub 2}O{sub 3} nanoparticles, while for films above a certain thickness {alpha}-Fe{sub 2}O{sub 3} and {gamma}-Fe{sub 2}O{sub 3} coexist, exhibiting two different crystallite sizes. TEM shows a characteristic particle diameter of {approx}7 nm for {gamma}-Fe{sub 2}O{sub 3} resulting from thermal treatment of monolayers, consistent with the crystallite size of the {gamma}-phase as obtained from XRD measurements on multi-layered samples. XRD shows the {alpha}-Fe{sub 2}O{sub 3} phase to be characterized by a crystallite size of {approx}34 nm.

  10. Electro-optical switching of liquid crystals of graphene oxide

    Science.gov (United States)

    Song, Jang-Kun

    Electric field effects on aqueous graphene-oxide (GO) dispersions are reviewed in this chapter. In isotropic and biphasic regimes of GO dispersions, in which the inter-particle friction is low, GO particles sensitively respond to the application of electric field, producing field-induced optical birefringence. The electro-optical sensitivity dramatically decreases as the phase transits to the nematic phase; the increasing inter-particle friction hinders the rotational switching of GO particles. The corresponding Kerr coefficient reaches the maximum near the isotropic to biphasic transition concentration, at which the Kerr coefficient is found be c.a. 1:8 · 10-5 mV-2, the highest value ever reported in all Kerr materials. The exceptionally large Kerr effect arises from the Maxwell- Wagner polarization of GO particles with an extremely large aspect ratio and a thick electrical double layer (EDL). The polarization sensitively depends on the ratio of surface and bulk conductivities in dispersions. As a result, low ion concentration in bulk solvent is highly required to achieve a quality electro-optical switching in GO dispersions. Spontaneous vinylogous carboxylic reaction in GO particles produces H+ ions, resulting in spontaneous degradation of electro-optical response with time, hence the removal of residual ions by using a centrifuge cleaning process significantly improves the electro-optical sensitivity. GO particle size is another important parameter for the Kerr coefficient and the response time. The best performance is observed in a GO dispersion with c.a. 0.5 μm mean size. Dielectrophoretic migration of GO particles can be also used to manipulate GO particles in solution. Using these unique features of GO dispersions, one can fabricate GO liquid crystal devices similar to conventional liquid crystal displays; the large Kerr effect allows fabricating a low power device working at extremely low electric fields.

  11. Oxide perovskite crystals for HTSC film substrates microwave applications

    Science.gov (United States)

    Bhalla, A. S.; Guo, Ruyan

    1995-01-01

    The research focused upon generating new substrate materials for the deposition of superconducting yttrium barium cuprate (YBCO) has yielded several new hosts in complex perovskites, modified perovskites, and other structure families. New substrate candidates such as Sr(Al(1/2)Ta(1/2))O3 and Sr(Al(1/2)Nb(1/2))O3, Ba(Mg(1/3)Ta(2/3))O3 in complex oxide perovskite structure family and their solid solutions with ternary perovskite LaAlO3 and NdGaO3 are reported. Conventional ceramic processing techniques were used to fabricate dense ceramic samples. A laser heated molten zone growth system was utilized for the test-growth of these candidate materials in single crystal fiber form to determine crystallographic structure, melting point, thermal, and dielectric properties as well as to make positive identification of twin free systems. Some of those candidate materials present an excellent combination of properties suitable for microwave HTSC substrate applications.

  12. Synthesis, Crystal Structure and Electrical Properties of the Molybdenum Oxide

    Directory of Open Access Journals (Sweden)

    Ennajeh Ines

    2013-01-01

    Full Text Available New molybdenum oxide Na1.92Mg2.04Mo3O12 has been synthesized by the solid state method. The title compound crystallizes in the triclinic system (space group P-1. The unit cell parameters are a = 6.9660(7 Å, b = 8.6352(8 Å, c = 10.2501(8 Å, α = 106.938(1°, β = 104.825(1°, γ = 103.206(1°, V = 538.72(9 Å3, and Z = 2. The compound is isotypical to Ag2M2(MoO43 (M = Zn, Mg, Co, Mn. The structure can be described as a three-dimensional anionic mixed framework of MoO4 tetrahedra and pairs of Mg2O10 octahedra sharing common edges. The Na+ ions are disordered and located in the voids forming infinite channels running along the direction [100]. The electrical conductivity investigated from 693 K to 793 K by AC impedance spectroscopy is low ( S cm−1 at 683 K.

  13. Thin films of metal oxides on metal single crystals: Structure and growth by scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Galloway, Heather Claire [Univ. of California, Berkeley, CA (United States)

    1995-12-01

    Detailed studies of the growth and structure of thin films of metal oxides grown on metal single crystal surfaces using Scanning Tunneling Microscopy (STM) are presented. The oxide overlayer systems studied are iron oxide and titanium oxide on the Pt(III) surface. The complexity of the metal oxides and large lattice mismatches often lead to surface structures with large unit cells. These are particularly suited to a local real space technique such as scanning tunneling microscopy. In particular, the symmetry that is directly observed with the STM elucidates the relationship of the oxide overlayers to the substrate as well as distinguishing, the structures of different oxides.

  14. Crystal structure of the uranyl-oxide mineral rameauite

    Energy Technology Data Exchange (ETDEWEB)

    Plasil, Jakub [ASCR, Prague (Czech Republic). Inst. of Physics; Skoda, Radek [Masaryk Univ., Brno (Czech Republic). Dept. of Geological Sciences; Cejka, Jiri [National Museum, Prague (Czech Republic). Dept. of Mineralogy and Petrology; Bourgoin, Vincent; Boulliard, Jean-Claude [Pierre et Marie Curie Univ., Paris (France). Association Jean Wyart, Collection des Mineraux de Jussieu

    2016-12-15

    Rameauite is a rare supergene uranyl-oxide hydroxy-hydrate mineral that forms during hydration-oxidation weathering of uraninite. On the basis of single-crystal X-ray diffraction data collected on a microfocus source, rameauite is monoclinic, space group Cc, with a = 13.9458(19), b = 14.3105(19), c = 13.8959(18) Aa, β = 118.477(14) , V = 2437.7(6) Aa{sup 3} and Z = 4, with D{sub calc} = 5.467 g cm{sup -3}. The structure of rameauite (R = 0.060 for 1698 unique observed reflections) contains sheets of the β-U{sub 3}O{sub 8} topology, with both UO{sub 6} and UO{sub 7} bipyramids, which is similar to the sheets found in spriggite, ianthinite and wyartite. The sheets alternate with the interlayer, which contains K{sup +}, Ca{sup 2+} and H{sub 2}O molecules. Interstitial cations are linked into infinite chains that extend along [10-1]. Adjacent sheets are linked through K-O, Ca-O and H-bonds. The structural formula of rameauite is K{sub 2} Ca(H{sub 2}{sup [3]}O){sub 1}(H{sub 2}{sup [5]}O){sub 4}[(UO{sub 2}) {sub 6}O{sub 6}(OH){sub 4}](H{sub 2}{sup [4]}O){sub 1}. The empirical formula obtained from the average of eight electron-microprobe analyses is (on the basi s of 6 U p.f.u.) K{sub 1.87}(Ca{sub 1.10}Sr{sub 0.04}){sub Σ1.14}[(UO 2){sub 6}O{sub 6}(OH){sub 4.15}].6H{sub 2}O. The Raman spectrum is dominate d by U.O and O.H vibrations. A discussion of related uranyl-oxide minerals is given.

  15. Study on crystallization behaviour of co-polyamide 66 containing triaryl phosphine oxide

    Indian Academy of Sciences (India)

    Yang Xiao Feng; Li Qiao Ling; Chen Zhi Ping; Yang Yong Feng; Zhang Lei

    2012-04-01

    In this paper, the isothermal crystallization and non-isothermal crystallization behaviour of flame retardant co-polyamide 66 (FR-PA66) containing triaryl phosphine oxide (TPO) were researched by employing differential scanning calorimetry (DSC), polarized optical microscopy (POM), respectively. The effects of TPO groups on nucleation mechanism, nucleation pattern and crystallization rate of FR-PA66 were discussed in detail. Experimental results show that TPO unit does not nucleate first during crystallization process of FR-PA66. The nucleationmechanism and nucleation pattern of FR-PA66 do not virtually change with incorporation of TPO groups when compared with polyamide 66 (PA66). The mainly crystallization process of FR-PA66 is still free nucleation and growing during the prime crystallization stage, and is unimensional nucleation and growing during the second crystallization stage. But at the second crystallization stage, we think there is a para-crystal forming with the maincrystal unimensional nucleation and growing. In addition, incorporation of TPO groups result in the decrement of both nucleation rate and crystallization rate of FR-PA66, and the increment of crystallization activation energy. Hence the TPO groups were unfavourable for FR-PA66 crystallization. In addition, incorporation of TPO groups also result in the decrement of crystallization region of FR-PA66, and increment of spherulite defect.

  16. Spectroscopy of photonic band gaps in mesoporous one-dimensional photonic crystals based on aluminum oxide

    Science.gov (United States)

    Gorelik, V. S.; Voinov, Yu. P.; Shchavlev, V. V.; Bi, Dongxue; Shang, Guo Liang; Fei, Guang Tao

    2016-12-01

    Mesoporous one-dimensional photonic crystals based on aluminum oxide have been synthesized by electrochemical etching method. Reflection spectra of the obtained mesoporous samples in a wide spectral range that covers several band gaps are presented. Microscopic parameters of photonic crystals are calculated and corresponding reflection spectra for the first six band gaps are presented.

  17. Magnesium oxide doping reduces acoustic wave attenuation in lithium metatantalate and lithium metaniobate crystals

    Science.gov (United States)

    Croft, W.; Damon, R.; Kedzie, R.; Kestigian, M.; Smith, A.; Worley, J.

    1970-01-01

    Single crystals of lithium metatantalate and lithium metaniobate, grown from melts having different stoichiometries and different amounts of magnesium oxide, show that doping lowers temperature-independent portion of attenuation of acoustic waves. Doped crystals possess optical properties well suited for electro-optical and photoelastic applications.

  18. Copper electrodeposition from cuprous chloride solutions containing lead, zinc or iron ions

    Institute of Scientific and Technical Information of China (English)

    M. Tchoumou; M. Roynette Ehics

    2005-01-01

    Cuprous chloride hydrochloric acid solutions were electrolysed in a two compartments cell without agitation for copper extraction. It is found that the current density affects the colour and the size of copper deposits. During electrodeposition of copper from cuprous solution in the presence of various concentrations of lead, zinc or iron ions at different current densities, it is observed that lead is codeposited with copper by increasing current density.In all experiments, the current efficiency for the copper deposition reaction fluctuates between 88.50% and 95.50%.

  19. MOLECULAR DYNAMICS SIMULATION OF INTERACTION BETWEEN CUPROUS OXIDE CRYSTAL AND BENZOTRIAZOLE DERIVATIVES%苯并三氮唑及其衍生物与氧化亚铜晶体相互作用的MD模拟

    Institute of Scientific and Technical Information of China (English)

    张曙光; 陈瑜; 王风云

    2007-01-01

    用分子动力学(MD)方法,模拟计算了4种铜缓蚀剂[苯并三氮唑(BTA)、5-羧甲基苯并三氮唑(CBTAH-ME)、5-羧丁基苯并三氮唑(CBTAH-BU)、5-羧辛基苯并三氮唑(CBTAH-OC)]与Cu2O晶体的相互作用.结果表明,缓蚀剂分子与Cu2O晶体的结合能排序为CBTAH-OC>CBTAH-BU>CBTAH-ME>BTA.对体系各种相互作用以及对关联函数g(r)的分析表明,体系结合能主要来自库仑作用.在与Cu2O(001)晶面结合过程中,BTA及其衍生物分子发生了扭曲变形,且分子中的N原子与Cu2O晶体中的Cu原子之间形成了配位键.

  20. The crystal chemistry of inorganic metal borohydrides and their relation to metal oxides.

    Science.gov (United States)

    Černý, Radovan; Schouwink, Pascal

    2015-12-01

    The crystal structures of inorganic homoleptic metal borohydrides are analysed with respect to their structural prototypes found amongst metal oxides in the inorganic databases such as Pearson's Crystal Data [Villars & Cenzual (2015). Pearson's Crystal Data. Crystal Structure Database for Inorganic Compounds, Release 2014/2015, ASM International, Materials Park, Ohio, USA]. The coordination polyhedra around the cations and the borohydride anion are determined, and constitute the basis of the structural systematics underlying metal borohydride chemistry in various frameworks and variants of ionic packing, including complex anions and the packing of neutral molecules in the crystal. Underlying nets are determined by topology analysis using the program TOPOS [Blatov (2006). IUCr CompComm. Newsl. 7, 4-38]. It is found that the Pauling rules for ionic crystals apply to all non-molecular borohydride crystal structures, and that the latter can often be derived by simple deformation of the close-packed anionic lattices c.c.p. and h.c.p., by partially removing anions and filling tetrahedral or octahedral sites. The deviation from an ideal close packing is facilitated in metal borohydrides with respect to the oxide due to geometrical and electronic considerations of the BH4(-) anion (tetrahedral shape, polarizability). This review on crystal chemistry of borohydrides and their similarity to oxides is a contribution which should serve materials engineers as a roadmap to design new materials, synthetic chemists in their search for promising compounds to be prepared, and materials scientists in understanding the properties of novel materials.

  1. Transient oxidation of single-crystal beta-NiAl

    Science.gov (United States)

    Doychak, J.; Smialek, J. L.; Mitchell, T. E.

    1989-01-01

    The transient oxidation of beta-NiAl in air at 800 C and 1100 C has been studied using electron microscopy. The oxide scale consists predominantly of metastable Al2O3 phases. Theta-Al2O3 is the major oxide phase within 10.0 hr of oxidation at 800 C and 0.1 hr at 1100 C. The scales form epitaxially on (001) sub beta and (012) sub beta specimens throughout the transient stage, whereas the degree of preferred oxide orientation decreases with oxidation time on (011) sub beta and (111) sub beta specimens. The orientation relationships reflect the small mismatch between parallel close-packed directions in the metal and in the cation sublattice of the oxides. The correlation of distinctive oxide surface morphologies with internal structural defects indicates the strong tendency of the Al2O3 scale to grow via short-circuit diffusion paths.

  2. Thermal Shock Behavior of Single Crystal Oxide Refractive Concentrators for High Temperatures Solar Thermal Propulsion

    Science.gov (United States)

    Zhu, Dongming; Choi, Sung R.; Jacobson, Nathan S.; Miller, Robert A.

    1999-01-01

    Single crystal oxides such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium-aluminum-garnet (Y3Al5O12, or YAG), magnesium oxide (MgO) and sapphire (Al2O3) have been considered as refractive secondary concentrator materials for high temperature solar propulsion applications. However, thermal mechanical reliability of the oxide components in severe thermal environments during space mission sun/shade transitions is of great concern. In this paper, critical mechanical properties of these oxide crystals are determined by the indentation technique. Thermal shock resistance of the oxides is evaluated using a high power CO, laser under high temperature-high thermal gradients. Thermal stress fracture behavior and failure mechanisms of these oxide materials are investigated under various temperature and heating conditions.

  3. The optical properties of bismuth germanium oxide single crystals

    Directory of Open Access Journals (Sweden)

    ANDREJA VALCIC

    2000-09-01

    Full Text Available Bi12GeO20 single crystals were grown by the Czochralski technique. Suitable polishing and etching solutions were determined. Reflection spectra were recorded in the wave numbers range 20–5000 cm–1, and compared with the spectra of Bi12SiO20 single crystals to study the position of the phonon modes. The optical constants of the Bi12GeO20 single crystals were obtained using Kramers-Kronig analysis. The obtained results are dicussed and compared with published data.

  4. Effect of Anodic Alumina Oxide Pore Diameter on the Crystallization of Poly(butylene adipate).

    Science.gov (United States)

    Sun, Xiaoli; Fang, Qunqun; Li, Huihui; Ren, Zhongjie; Yan, Shouke

    2016-04-05

    Poly(butylene adipate) (PBA) was infiltrated into the anodic alumina oxide (AAO) templates with the pore diameter of around 30, 70, and 100 nm and PBA nanotubes with different diameters were prepared. The crystallization and phase transition behavior of the obtained PBA nanotubes capped in the nanopores have been explored by using X-ray diffraction and differential scanning calorimetry. Only α-PBA crystals form in the bulk sample during nonisothermal crystallization. By contrast, predominant β-PBA crystals form in the AAO templates. The β-PBA crystals formed in the nanopores with pore diameter less than 70 nm prefer to adopt an orientation with their b-axis parallel to the long axis of the pore. During the melt recrystallization, it was found that the critical temperature (Tβ), below which pure β-crystals form, is 20 °C for bulk PBA. It drops down significantly with the pore diameter for the PBA in the AAO template. Moreover, the β-crystals in the porous template exhibit larger lattice parameters compared with the bulk crystals. By monitoring the change of β-crystals in the heating process, it was found that β-crystals in the AAO template with the pore diameter of 30 nm (D30) melt directly while the β-crystals transform to α-crystals in the template with the pore diameter of 100 nm (D100). The intensity of (020) Bragg peak of β-crystals decreases at a similar rate in both D30 and D100 but disappears at a relatively lower temperature in D30. On the other hand, the β(110) peak intensity of β-PBA crystals formed in the D100 template decreases first at slower rate before α crystals appear, and then at a faster rate once the β to α phase transition takes place.

  5. DC electrical conductivity measurements for pure and titanium oxide doped KDP Crystals grown by gel medium

    Science.gov (United States)

    Mareeswaran, S.; Asaithambi, T.

    2016-10-01

    Now a day's crystals are the pillars of current technology. Crystals are applied in various fields like fiber optic communications, electronic industry, photonic industry, etc. Crystal growth is an interesting and innovative field in the subject of physics, chemistry, material science, metallurgy, chemical engineering, mineralogy and crystallography. In recent decades optically good quality of pure and metal doped KDP crystals have been grown by gel growth method in room temperature and its characterizations were studied. Gel method is a very simple and one of the easiest methods among the various crystal growth methods. Potassium dihydrogen phosphate KH2PO4 (KDP) continues to be an interesting material both academically and technologically. KDP is a delegate of hydrogen bonded materials which possess very good electrical and nonlinear optical properties in addition to interesting electro-optic properties. We made an attempt to grow pure and titanium oxide doped KDP crystals with various doping concentrations (0.002, 0.004, 0.006, 0.008 and 0.010) using gel method. The grown crystals were collected after 20 days. We get crystals with good quality and shaped crystals. The dc electrical conductivity (resistance, capacitance and dielectric constant) values of the above grown crystals were measured at two different frequencies (1KHz and 100 Hz) with a temperature range of 500C to 1200C using simple two probe setup with Q band digital LCR meter present in our lab. The electrical conductivity increases with the increase of temperature. Dielectric constants value of titanium oxide doped KDP crystal was slightly decreased compared with pure KDP crystals. Results were discussed in details.

  6. Crystallization study of Cu{sub 2}O and their characterization for X-ray diffraction, Raman spectroscopy and photoluminescence; Estudio de la cristalizacion de Cu{sub 2}O y su caracterizacion por difraccion de rayos X, espectroscopica Raman y fotoluminiscencia

    Energy Technology Data Exchange (ETDEWEB)

    Solache C, H.; Juarez D, G.; Pena S, R. [Departamento de Ingenieria Electrica, SEES, Centro de Investigacion y de Estudios Avanzados, IPN, Av. Instituto Politecnico 2805, Col. Zacatenco, 07000 Mexico D. F. (Mexico); Martinez J, J. [Centro de Investigacion en Dispositivos Semiconductores, Benemerita Universidad Autonoma de Puebla, 14 Sur y Av. San Claudio, 72570 Puebla (Mexico)], e-mail: hsolache@cinvestav.mx

    2009-07-01

    The growth of polycrystalline cuprous oxide (Cu{sub 2}O) foils with great single-crystalline areas by the secondary crystallization method from polycrystalline copper in dry air atmosphere is reported. The method comprises two stages; in the first one polycrystalline copper foils were converted in cuprous oxide at 1020 C by some hours depending of their thickness, in the second stage the growth of great crystalline areas are promoted by annealing the Cu{sub 2}O foils at temperatures near to 1100 C by extended periods. The growth kinetics of the crystallites was studied; X-ray diffraction (XRD), Raman spectroscopy scattering and photoluminescence (Pl) measurements were done as a function of the crystallization conditions. The XRD and Raman scattering measurements reveal the existence of pure Cu{sub 2}O phase. The Pl spectra taken from 10 to 180 K define the main paths of the radiative recombination processes. Besides of the excitonic transition X at 610 nm, three strong bands at 720, 810 and 920 nm associated with relaxed excitons at oxygen and copper vacancies, respectively was detected. The relative intensity of the Pl transitions of excitons at vacancies change according to the duration of the crystallization process. (Author)

  7. Hydrothermal crystal growth of oxides for optical applications

    Science.gov (United States)

    McMillen, Colin David

    2007-12-01

    The manipulation of light has proven to be an integral part of today's technology-based society. In particular, there is great interest in obtaining coherent radiation in all regions of the optical spectrum to advance technology in military, medical, industrial, scientific and consumer fields. Exploring new crystal growth techniques as well as the growth of new optical materials is critical in the advancement of solid state optics. Surprisingly, the academic world devotes little attention to the growth of large crystals. This shortcoming has left gaps in the optical spectrum inaccessible by solid state devices. This dissertation explores the hydrothermal crystal growth of materials that could fill two such gaps. The first gap exists in the deep-UV region, particularly below 200 nm. Some materials such as LiB3O5 and beta-BaB2O4 can generate coherent light at wavelengths as low as 205 nm. The growth of these materials was explored to investigate the feasibility of the hydrothermal method as a new technique for growing these crystals. Particular attention was paid to the descriptive chemistry surrounding these systems, and several novel structures were elucidated. The study was also extended to the growth of materials that could be used for the generation of coherent light as low as 155 nm. Novel synthetic schemes for Sr2Be2B2O7 and KBe2BO 3F2 were developed and the growth of large crystals was explored. An extensive study of the structures, properties and crystal growth of related compounds, RbBe2BO3F2 and CsBe2BO 3F2, was also undertaken. Optimization of a number of parameters within this family of compounds led to the hydrothermal growth of large, high quality single crystal at rates suitable for large-scale growth. The second gap in technology is in the area of high average power solid state lasers emitting in the 1 mum and eye-safe (>1.5 mum) regions. A hydrothermal technique was developed to grow high quality crystals of Sc 2O3 and Sc2O3 doped with suitable

  8. Kinetic study of CO oxidation on step decorated Pt(1 1 1) vicinal single crystal electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Chen Qingsong [Institute of Electrochemistry, University of Alicante, Apartado 99, E-03080 Alicante (Spain); State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Feliu, Juan M., E-mail: juan.feliu@ua.es [Institute of Electrochemistry, University of Alicante, Apartado 99, E-03080 Alicante (Spain); Berna, Antonio; Climent, Victor [Institute of Electrochemistry, University of Alicante, Apartado 99, E-03080 Alicante (Spain); Sun Shigang, E-mail: sgsun@xmu.edu.cn [State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China)

    2011-07-01

    Highlights: > Chronoamperometry has been used to study CO oxidation on Pt stepped surfaces. > Adatoms step decoration allows determination of the role of steps on CO oxidation. > Rate constant decreases after step decoration with adatoms. > Tafel slopes are around 60-90 mV/dec, suggesting a Langmuir-Hinshelwood mechanism. - Abstract: In this work, surface modification at atomic level was applied to study the reactivity of step sites on platinum single crystal surfaces. Stepped platinum single crystal electrodes with (1 1 1) terraces separated by monoatomic step sites with different symmetry were decorated with irreversibly adsorbed adatoms, without blocking the terrace sites, and characterized in 0.1 M HClO{sub 4} solution. The kinetics of CO oxidation on the different platinum single crystal planes as well as on the step decorated surfaces has been studied using chronoamperometry. The apparent rate constants, which were determined by fitting the experimental data to a mean-field model, decrease after the steps of platinum single crystal electrodes have been blocked by the adatoms. This behavior indicates that steps are active sites for CO oxidation. Tafel slopes measured from the potential dependence of the apparent rate constants of CO oxidation were similar in all cases. This result demonstrates that the electrochemical oxidation of the CO adlayer on all the surfaces follows the same Langmuir-Hinshelwood model, irrespectively of step modification.

  9. Single crystals of bismuth silicon oxide grown by the Czochralski technique and their characterisation

    Directory of Open Access Journals (Sweden)

    ANDREJA VALCIC

    1999-09-01

    Full Text Available Single crystals of Bi12SiO20 were grown by the Czochralski technique. The critical diameter and the critical rate of rotation were calculated. Suitable polishing and etching solutions were determined. X-Ray measurements were performed on powdered samples to obtain the lattice parameters. The optical properties of the bismuth silicon oxide single crystals were investigated. The obtained results are discussed and compared with published data.

  10. Selective tuning of high-Q silicon photonic crystal nanocavities via laser-assisted local oxidation

    CERN Document Server

    Chen, Charlton J; Gu, Tingyi; McMillan, James F; Yu, Mingbin; Lo, Guo-Qiang; Kwong, Dim-Lee; Wong, Chee Wei

    2011-01-01

    We examine the cavity resonance tuning of high-Q silicon photonic crystal heterostructures by localized laser-assisted thermal oxidation using a 532 nm continuous wave laser focused to a 2.5 mm radius spot-size. The total shift is consistent with the parabolic rate law. A tuning range of up to 8.7 nm is achieved with ~ 30 mW laser powers. Over this tuning range, the cavity Q decreases from 3.2\\times10^5 to 1.2\\times10^5. Numerical simulations model the temperature distributions in the silicon photonic crystal membrane and the cavity resonance shift from oxidation.

  11. Analysis of the temperature dependence of the thermal conductivity of insulating single crystal oxides

    Directory of Open Access Journals (Sweden)

    E. Langenberg

    2016-10-01

    Full Text Available The temperature dependence of the thermal conductivity of 27 different single crystal oxides is reported from ≈20 K to 350 K. These crystals have been selected among the most common substrates for growing epitaxial thin-film oxides, spanning over a range of lattice parameters from ≈3.7 Å to ≈12.5 Å. Different contributions to the phonon relaxation time are discussed on the basis of the Debye model. This work provides a database for the selection of appropriate substrates for thin-film growth according to their desired thermal properties, for applications in which heat management is important.

  12. Relationship between surface area and crystal size of pure and doped cerium oxides

    Institute of Scientific and Technical Information of China (English)

    C.; Bueno-Ferrer; S.; Parres-Esclapez; D.; Lozano-Castelló; A.; Bueno-López

    2010-01-01

    Pure and Zr, La or Pr-doped cerium oxides were characterised by transmission electron microscopy (TEM), N2 adsorption-desorption at -196 oC and X-ray diffraction (XRD). For crystal sizes calculation, the Scherrer and Williamson-Hall equations were compared, and the relationship between surface area and crystal size was critically discussed. It was demonstrated that the Williamson-Hall equation must be used instead of the Scherrer equation to calculate crystal sizes, since the latter equation underestimated ...

  13. Fabrication of inverted zinc oxide photonic crystal using sol-gel solution by spin coating method.

    Science.gov (United States)

    Huang, Kuo-Min; Ho, Chong-Lung; Chang, Heng-Jui; Wu, Meng-Chyi

    2013-01-01

    Inverted zinc oxide photonic crystal structures were fabricated from polystyrene sphere (PSS) template using the sol-gel solution of ZnO by spin-coating method. It is easily able to control and fabricate the photonic crystal structures using the self-organized PSS with a size of 193 nm. The inverted ZnO photonic crystal structures observed show the (111) tendency of the hexagonal compact arrangement formation. The resulting structures possess the photonic band gaps in the near-ultraviolet range and exhibit an enhanced photoluminescence spectrum. The technology can effectively increase the light output intensity or efficiency for the applications of optoelectronic devices.

  14. Role of Internal Radiation in Oxide Crystal Growth by Heat Exchanger Method

    Directory of Open Access Journals (Sweden)

    Wencheng Ma

    2017-01-01

    Full Text Available Internal radiation was investigated using the finite volume method for the heat exchanger method (HEM growth of oxide crystals. Special attention was devoted to the temperature and thermal stress distributions in the bottom region of the grown crystal at the end of the solidification process. The numerical results show that internal radiation strongly strengthens heat transport through the crystal. However, it causes isotherms to intensively concentrate in the crystal bottom region, leading to a significant increase in the temperature gradient and thermal stress in this region. Then, the effect of absorption coefficient on this phenomenon was numerically investigated. It was found that the radiation heat transfer rate at the bottom surface of the crystal monotonically decreases as the absorption coefficient is increased, while the conduction heat transfer rate first increases and then decreases as the absorption coefficient is increased, under the interaction between internal radiation and heat conduction. The variations of the maximum temperature gradient and thermal stress in the crystal bottom show the same tendency as the conduction heat transfer rate. This study indicates that the role of internal radiation on the heat transfer and thermal stress in oxide crystal by HEM process shows some differences from that by Czochralski and Kyropoulos processes.

  15. Confinement effects on the crystallization of poly(ethylene oxide) nanotubes.

    Science.gov (United States)

    Maiz, Jon; Martin, Jaime; Mijangos, Carmen

    2012-08-21

    In this work, we show the effects of nanoconfinement on the crystallization of poly(ethylene oxide) (PEO) nanotubes embedded in anodized aluminum oxide (AAO) templates. The morphological characteristics of the hollow 1D PEO nanostructures were evaluated by scanning electron microscopy (SEM). The crystallization of the PEO nanostructures and bulk was studied with differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). The crystallization of PEO nanotubes studied by DSC is strongly influenced by the confinement showing a strong reduction in the crystallization temperature of the polymer. X-ray diffraction (XRD) experiments confirmed the isothermal crystallization results obtained by DSC, and studies carried out at low temperatures showed the absence of crystallites oriented with the extended chains perpendicular to the pore wall within the PEO nanotubes, which has been shown to be the typical crystal orientation for one-dimensional polymer nanostructures. In contrast, only planes oriented 33, 45, and 90° with respect to the plane (120) are arranged parallel to the pore's main axis, indicating preferential crystal growth in the direction of the radial component. Calculations based on classical nucleation theory suggest that heterogeneous nucleation prevails in the bulk PEO whereas for the PEO nanotubes a surface nucleation mechanism is more consistent with the obtained results.

  16. GaInP on oxide nonlinear photonic crystal technology.

    Science.gov (United States)

    Martin, Aude; Sanchez, Dorian; Combrié, Sylvain; de Rossi, Alfredo; Raineri, Fabrice

    2017-02-01

    Heat dissipation is improved in nonlinear III-V photonic crystal waveguides owing to the hybrid III-V/Silicon integration platform, allowing efficient four-wave mixing in the continuous-wave regime. A conversion efficiency of -17.6  dB is demonstrated with a pump power level below 100 mW in a dispersion-engineered waveguide with a flat group index of 28 over a 10 nm bandwidth.

  17. The thickness of native oxides on aluminum alloys and single crystals

    OpenAIRE

    Evertsson, J.; Bertram, F.; Weissenrieder, J.; Goethelid, Mats; Pan, J; Mikkelsen, A.; Nilsson, J.-O.; Lundgren, E.; Zhang, F.; Rullik, L.; Merte, L. R.; Shipilin, Mikhail; Soldemo, M.; S Ahmadi; Vinogradov, N.

    2015-01-01

    We present results from measurements of the native oxide film thickness on four different industrial aluminum alloys and three different aluminum single crystals. The thicknesses were determined using X-ray reflectivity, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. In addition, atomic force microscopy was used for micro-structural studies of the oxide surfaces. The reflectivity measurements were performed in ultra-high vacuum, vacuum, ambient, nitrogen and liq...

  18. Cell adhesion of Shewanella oneidensis to iron oxide minerals: Effect of different single crystal faces

    OpenAIRE

    Hochella Michael F; Bank Tracy L; Neal Andrew L; Rosso Kevin M

    2005-01-01

    The results of experiments designed to test the hypothesis that near-surface molecular structure of iron oxide minerals influences adhesion of dissimilatory iron reducing bacteria are presented. These experiments involved the measurement, using atomic force microscopy, of interaction forces generated between Shewanella oneidensis MR-1 cells and single crystal growth faces of iron oxide minerals. Significantly different adhesive force was measured between cells and the (001) face of hematite,...

  19. Radiation Detection and Classification of Heavy Oxide Inorganic Scintillator Crystals for Detection of Fast Neutrons

    Science.gov (United States)

    2016-06-01

    and alkali-halide scintillators for potential use in neutron and gamma detection systems .” M.S. thesis, Dept. Physics , Naval Posgraduate School...DETECTION AND CLASSIFICATION OF HEAVY OXIDE INORGANIC SCINTILLATOR CRYSTALS FOR DETECTION OF FAST NEUTRONS by Jacob W. Capps June 2016 Thesis...DATE June 2016 3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE RADIATION DETECTION AND CLASSIFICATION OF HEAVY OXIDE

  20. Electrochemical oxidation of carbon monoxide: from platinum single crystals to low temperature fuel cells catalysts. Part I: Carbon monoxide oxidation onto low index platinum single crystals

    Directory of Open Access Journals (Sweden)

    PHILIP N. ROSS JR

    2001-12-01

    Full Text Available The electrochemical oxidation of carbon monoxide and the interfacial structure of the CO adlayer (COads on platinum low index single crystals, Pt(111, Pt(100 and two reconstruction of Pt(110, were examined using the rotation disk electrode method in combination with the in situ surface X-ray diffraction scattering technique. The mechanism of CO oxidation is discussed on the basis of the findings that, depending on the potential, two energetic states of COads exist on the platinum surfaces. Thus, at lower potentials, weakly bonded states (COads,w and at higher potentials strongly bonded states (COads,s are formed. The mechanism of the oxidation of hydrogen-carbon monoxide mixtures is also proposed.

  1. The thickness of native oxides on aluminum alloys and single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Evertsson, J., E-mail: jonas.evertsson@sljus.lu.se [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden); Bertram, F. [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden); Zhang, F. [KTH Royal Institute of Technology, Department of Chemistry, Division of Surface and Corrosion Science, Drottning Kristinas Vg 51, 100 44 Stockholm (Sweden); Rullik, L.; Merte, L.R.; Shipilin, M. [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden); Soldemo, M.; Ahmadi, S. [KTH Royal Institute of Technology, ICT, Material Physics, 16440 Kista (Sweden); Vinogradov, N.; Carlà, F. [ESRF, B.P. 220, 38043 Grenoble (France); Weissenrieder, J.; Göthelid, M. [KTH Royal Institute of Technology, ICT, Material Physics, 16440 Kista (Sweden); Pan, J. [KTH Royal Institute of Technology, Department of Chemistry, Division of Surface and Corrosion Science, Drottning Kristinas Vg 51, 100 44 Stockholm (Sweden); Mikkelsen, A. [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden); Nilsson, J.-O. [Sapa Technology, Kanalgatan 1, 612 31 Finspång (Sweden); Lundgren, E. [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden)

    2015-09-15

    Highlights: • We have determined the native oxide film thickness on several Al samples. • The results obtained from XRR and XPS show excellent agreement. • The results obtained from EIS show consistently thinner oxide films. • The oxides on the alloys are thicker than the oxides on the single crystals. - Abstract: We present results from measurements of the native oxide film thickness on four different industrial aluminum alloys and three different aluminum single crystals. The thicknesses were determined using X-ray reflectivity, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. In addition, atomic force microscopy was used for micro-structural studies of the oxide surfaces. The reflectivity measurements were performed in ultra-high vacuum, vacuum, ambient, nitrogen and liquid water conditions. The results obtained using X-ray reflectivity and X-ray photoelectron spectroscopy demonstrate good agreement. However, the oxide thicknesses determined from the electrochemical impedance spectroscopy show a larger discrepancy from the above two methods. In the present contribution the reasons for this discrepancy are discussed. We also address the effect of the substrate type and the presence of water on the resultant oxide thickness.

  2. Transmittance and Refractive Index of the Lanthanum Strontium Aluminium Tantalum Oxide Crystal

    Institute of Scientific and Technical Information of China (English)

    HU Bo-Qing; WANG Xiao-Ming; ZHOU Tang; ZHAO Zong-Yuan; WU Xing; CHEN Xiao-Long

    2001-01-01

    The lanthanum strontium aluminium tantalum oxide (LSAT) crystal is grown by means of a floating or pulling method. Its optical transmittance, refractive indices in visible and near-infrared areas and its dispersion curve are reported. The transparence range of LSAT is from 0.45 to 4.2μm and its refractive index is 2.0244.

  3. Eliminating Crystals in Non-Oxide Optical Fiber Preforms and Optical Fibers

    Science.gov (United States)

    Tucker, Dennis S.; LaPointe, Michael R.

    2012-01-01

    Non ]oxide fiber optics such as heavy metal fluoride and chalcogenide glasses are extensively used in infrared transmitting applications such as communication systems, chemical sensors, and laser fiber guides for cutting, welding and medical surgery. The addition of rare earths such as erbium, enable these materials to be used as fiber laser and amplifiers. Some of these glasses however are very susceptible to crystallization. Even small crystals can lead to light scatter and a high attenuation coefficient, limiting their usefulness. Previously two research teams found that microgravity suppressed crystallization in heavy metal fluoride glasses. Looking for a less expensive method to suppress crystallization, ground based research was performed utilizing an axial magnetic field. The experiments revealed identical results to those obtained via microgravity processing. This research then led to a patented process for eliminating crystals in optical fiber preforms and the resulting optical fibers. In this paper, the microgravity results will be reviewed as well as patents and papers relating to the use of magnetic fields in various material and glass processing applications. Finally our patent to eliminate crystals in non ]oxide glasses utilizing a magnetic field will be detailed.

  4. Oxidation kinetics of crystal violet by potassium permanganate in acidic medium

    Science.gov (United States)

    Khan, Sameera Razi; Ashfaq, Maria; Mubashir; Masood, Summyia

    2016-05-01

    The oxidation kinetics of crystal violet (a triphenylmethane dye) by potassium permanganate was focused in an acidic medium by the spectrophotometric method at 584 nm. The oxidation reaction of crystal violet by potassium permanganate is carried out in an acidic medium at different temperatures ranging within 298-318 K. The kinetic study was carried out to investigate the effect of the concentration, ionic strength and temperature. The reaction followed first order kinetics with respect to potassium permanganate and crystal violet and the overall rate of the reaction was found to be second order. Thermodynamic activation parameters like the activation energy ( E a), enthalpy change (Δ H*), free energy change (Δ G*), and entropy change (Δ S*) have also been evaluated.

  5. Crystal structure of the TLDc domain of oxidation resistance protein 2 from zebrafish

    DEFF Research Database (Denmark)

    Blaise, Mickael; Alsarraf, Husam Mohammad Ali Baker; Wong, Jaslyn

    2012-01-01

    The oxidation resistance proteins (OXR) help to protect eukaryotes from reactive oxygen species. The sole C-terminal domain of the OXR, named TLDc is sufficient to perform this function. However, the mechanism by which oxidation resistance occurs is poorly understood. We present here the crystal...... structure of the TLDc domain of the oxidation resistance protein 2 from zebrafish. The structure was determined by X-ray crystallography to atomic resolution (0.97Å) and adopts an overall globular shape. Two antiparallel β-sheets form a central β-sandwich, surrounded by two helices and two one-turn helices...

  6. Unique Crystal Orientation of Poly(ethylene oxide) Thin Films by Crystallization Using a Thermal Gradient

    DEFF Research Database (Denmark)

    Gbabode, Gabin; Delvaux, Maxime; Schweicher, Guillaume

    2017-01-01

    Poly(ethylene oxide), (PEO), thin films of different thicknesses (220, 450, and 1500 nm) and molecular masses (4000, 8000, and 20000 g/mol) have been fabricated by spin-coating of methanol solutions onto glass substrates. All these samples have been recrystallized from the melt using a directional...

  7. Tunable Nanostructures and Crystal Structures in Titanium Oxide Films

    Directory of Open Access Journals (Sweden)

    Fuess H

    2008-01-01

    Full Text Available Abstract Controllable nanostructures in spin coated titanium oxide (TiO2 films have been achieved by a very simple means, through change of post deposition annealing temperature. Electron beam imaging and reciprocal space analysis revealed as-deposited TiO2films to be characterized by a dominant anatase phase which converts to the rutile form at 600 °C and reverts to the anatase modification at 1,200 °C. The phase changes are also accompanied by changes in the film microstructure: from regular nanoparticles (as-deposited to nanowires (600 °C and finally to dendrite like shapes at 1,200 °C. Photoluminescence studies, Raman spectral results, and X-ray diffraction data also furnish evidence in support of the observed solid state phase transformations in TiO2.

  8. Effect of copper doping on the crystal structure and morphology of 1D nanostructured manganese oxides.

    Science.gov (United States)

    Lee, Sun Hee; Park, Dae Hoon; Hwang, Seong-Ju; Choy, Jin-Ho

    2007-11-01

    We have tried to control the aspect ratio and physicochemical properties of 1D nanostructured manganese oxides through copper doping. Copper-doped manganese oxide nanostructures have been synthesized by one-pot hydrothermal treatment for the mixed solution of permanganate anions and copper cations. According to powder X-ray diffraction and electron microscopic analyses, all the present materials commonly crystallize with alpha-MnO2-type structure but their aspect ratio decreases significantly with increasing the content of copper. Such a variation of crystallite dimension is attributable to the limitation of crystal growth by the incorporation of copper ions. X-ray absorption spectroscopic studies at Mn K- and Cu K-edges clearly demonstrate that the average oxidation state of manganese ions is increased by the substitution of divalent copper ions. Electrochemical measurements reveal the improvement of the electrode performance of nanostructured manganate upon copper doping, which can be interpreted as a result of the decrease of aspect ratio and the increase of Mn valence state. From the present experimental findings, it becomes certain that the present Cu doping method can provide an effective way of controlling the crystal dimension and electrochemical property of 1D nanostructured manganese oxide.

  9. Controllable cyanation of carbon-hydrogen bonds by zeolite crystals over manganese oxide catalyst

    Science.gov (United States)

    Wang, Liang; Wang, Guoxiong; Zhang, Jian; Bian, Chaoqun; Meng, Xiangju; Xiao, Feng-Shou

    2017-05-01

    The synthesis of organic nitriles without using toxic cyanides is in great demand but challenging to make. Here we report an environmentally benign and cost-efficient synthesis of nitriles from the direct oxidative cyanation of primary carbon-hydrogen bonds with easily available molecular oxygen and urea. The key to this success is to design and synthesize manganese oxide catalysts fixed inside zeolite crystals, forming a manganese oxide catalyst with zeolite sheath (MnOx@S-1), which exhibits high selectivity for producing nitriles by efficiently facilitating the oxidative cyanation reaction and hindering the side hydration reaction. The work delineates a sustainable strategy for synthesizing nitriles while avoiding conventional toxic cyanide, which might open a new avenue for selective transformation of carbon-hydrogen bonds.

  10. Investigation on bismuth-oxide photonic crystal fiber for optical parametric amplification

    Institute of Scientific and Technical Information of China (English)

    JIN Cang; RAO Lan; YUAN Jin-hui; SHEN Xiang-wei; YU Chong-xiu

    2011-01-01

    A hexagonal solid-core bismuth-oxide micro-structure fiber is developed to balance its dispersion and nonlinearity. This simulation and calculation results show that the bismuth-oxide photonic crystal fiber (Bi-PCF) has near zero dispersion around 1550 nm. Its dispersion slop in the communication wavelength range is also relatively flat. Moreover, both nonlinear coefficient and model field distribution are obtained. Compared with the experimental results by SiO-PCF, it can be seen that the Bi-PCF shows excellent characteristics for the optical parametric amplification (OPA).

  11. Liquid crystal terahertz phase shifters with functional indium-tin-oxide nanostructures for biasing and alignment

    Science.gov (United States)

    Yang, Chan-Shan; Tang, Tsung-Ta; Pan, Ru-Pin; Yu, Peichen; Pan, Ci-Ling

    2014-04-01

    Indium Tin Oxide (ITO) nanowhiskers (NWhs) obliquely evaporated by electron-beam glancing-angle deposition can serve simultaneously as transparent electrodes and alignment layer for liquid crystal (LC) devices in the terahertz (THz) frequency range. To demonstrate, we constructed a THz LC phase shifter with ITO NWhs. Phase shift exceeding π/2 at 1.0 THz was achieved in a ˜517 μm-thick cell. The phase shifter exhibits high transmittance (˜78%). The driving voltage required for quarter-wave operation is as low as 5.66 V (rms), compatible with complementary metal-oxide-semiconductor (CMOS) and thin-film transistor (TFT) technologies.

  12. ELECTROCHEMICAL OXIDATION OF La2CuO4 SINGLE CRYSTALS

    Institute of Scientific and Technical Information of China (English)

    Chen Ling; Huang Yu-zhen; Zhou Fang; Dong Cheng; Che Guang-can; Zhao Zhong-xian

    2000-01-01

    Bulk superconducting La2CuO4+ single crystals are obtained byusing electrochemical intercalation technique from the as-growninsulating samples. Oxidation is carried out by constant currentI=10 at temperature T=70 and room temperature, respectively. Structure and magnetic properties are studied by low-temperature X-ray diffraction and susceptibility measurements. A superconducting phase with Tc of 19K and -0.12 can be attributed to the formation of oxygen clusters. Room temperature oxidation is inhomogeneous: two superconducting phases with T c1 of 24K and Tc2 of 8K and an antiferromagnetic phase are coexisting in the crystal. It is found that the appearance of Tc in this system has the step tendency.

  13. Characterization of Anodic Aluminum Oxide Membrane with Variation of Crystallizing Temperature for pH Sensor.

    Science.gov (United States)

    Yeo, Jin-Ho; Lee, Sung-Gap; Jo, Ye-Won; Jung, Hye-Rin

    2015-11-01

    We fabricated electrolyte-dielectric-metal (EDM) device incorporating a high-k Al2O3 sensing membrane from a porous anodic aluminum oxide (AAO) using a two step anodizing process for pH sensors. In order to change the properties of the AAO template, the crystallizing temperature was varied from 400 degrees C to 700 degrees C over 2 hours. The structural properties were observed by field emission scanning electron microscopy (FE-SEM). The pH sensitivity increased with an increase in the crystallizing temperature from 400 degrees C to 600 degrees C. However at 700 degrees C, deformation occurred. The porous AAO sensor with a crystallizing temperature of 600 degrees C displayed the good sensitivity and long-term stability and the values were 55.7 mV/pH and 0.16 mV/h, respectively.

  14. Single crystal growth from separated educts and its application to lithium transition-metal oxides

    Science.gov (United States)

    Freund, F.; Williams, S. C.; Johnson, R. D.; Coldea, R.; Gegenwart, P.; Jesche, A.

    2016-01-01

    Thorough mixing of the starting materials is the first step of a crystal growth procedure. This holds true for almost any standard technique, whereas the intentional separation of educts is considered to be restricted to a very limited number of cases. Here we show that single crystals of α-Li2IrO3 can be grown from separated educts in an open crucible in air. Elemental lithium and iridium are oxidized and transported over a distance of typically one centimeter. In contrast to classical vapor transport, the process is essentially isothermal and a temperature gradient of minor importance. Single crystals grow from an exposed condensation point placed in between the educts. The method has also been applied to the growth of Li2RuO3, Li2PtO3 and β-Li2IrO3. A successful use of this simple and low cost technique for various other materials is anticipated. PMID:27748402

  15. Low Temperature Synthesis of Metal Oxides by a Supercritical Seed Enhanced Crystallization (SSEC) Process

    DEFF Research Database (Denmark)

    Jensen, Henrik; Brummerstedt Iversen, Steen; Joensen, Karsten Dan

    2006-01-01

    A novel method for producing crystalline nanosized metal oxides by a Supercritical Seed Enhanced Crystallization (SSEC) Process has been developed. The process is a modified sol-gel process taking place at temperatures as low as 95 ºC with supercritical CO2 as solvent and polypropylene as seeding....... The crystallinity can be controlled by changing the heating rate of the initial formation of the nanoparticles and the morphology can be altered by changing the process time....

  16. Crystallization and deuterium permeation behaviors of yttrium oxide coating prepared by metal organic decomposition

    Directory of Open Access Journals (Sweden)

    Takumi Chikada

    2016-12-01

    Full Text Available Yttrium oxide coatings were fabricated on reduced activation ferritic/martensitic steels by metal organic decomposition with a dip-coating technique, and their deuterium permeation behaviors were investigated. The microstructure of the coatings varied with heat-treatment temperature: amorphous at 670ºC (amorphous coating and crystallized at 700ºC (crystallized coating. Deuterium permeation flux of the amorphous coating was lower than the uncoated steel by a factor of 5 at 500ºC, while that of the crystallized coating was lower by a factor of around 100 at 400‒550ºC. The permeation fluxes of both coatings were drastically decreased during the measurements at higher temperatures by a factor of up to 790 for the amorphous coating and 1000 for the crystallized one, indicating a microstructure modification occurred by an effect of test temperature with hydrogen flux. Temperature dependence of deuterium diffusivity in the coatings suggests that the decrease of the permeation flux has been derived from a decrease of the diffusivity. Characteristic permeation behaviors were observed with different annealing conditions; however, they can be interpreted using the permeation mechanism clarified in the previous erbium oxide coating studies.

  17. Thermo-optical properties of beryllium containing oxide crystals as materials for high power laser systems

    Science.gov (United States)

    Pestryakov, E. V.; Petrov, V. V.; Trunov, V. I.; Kirpichnikov, A. V.; Laptev, A. V.; Matrosov, V. N.

    2007-06-01

    The elastic and thermo-optical properties of chrysoberyl, beryllium hexaaluminate and beryllium-lanthanum hexaaluminate crystals have been experimentally studied. The velocities of elastic-wave propagation in the crystals are measured by acousto-optic interference method. The values of all the independent components of elastic-constant tensor are determined and used to calculate a number of important dynamic parameters of the crystals such as the Young's and shear moduli, the modulus of volume elasticity, Poisson's ratio, the Debye temperature. Also measurements of refractive indices in 25 - 75 C temperature range in VIS spectral region were performed. Using experimental data the dispersion of thermal optical coefficients (dn/dT) was calculated, these data were employed to evaluate the thermal lens in beryllium containing laser crystals. The experimental and calculated data are compared with similar parameters for well-known laser hosts. Some of beryllium containing oxide crystals was shown to be candidates for master oscillator and amplifying stages of high power femtosecond laser systems.

  18. MOLECULAR WEIGHT DEPENDENCE OF CRYSTAL PATTERN TRANSITIONS OF POLY(ETHYLENE OXIDE)

    Institute of Scientific and Technical Information of China (English)

    Guo-liang Zhang; Liu-xin Jin; Ping Zheng; Wei Wang; Xiao-jing Wen

    2013-01-01

    Crystal patterns in ultrathin films of six poly(ethylene oxide) fractions with molecular weights from 25000 to 932000 g/mol were characterized within crystallization temperature range from 20 ℃ to 60 ℃.Labyrinthine,dendritic and faceted crystal patterns were observed in different temperature ranges,and then labyrinthine-to-dendritic and dendritic-tofaceted transition temperatures TL-D and TD-F were quantitatively identified.Their molecular weight dependences are TL-D(Mw) =TL-D(∞)-KL-D/Mw,where TL-D(∞) =38.2 ℃ and KL-D =253000 ℃·g/mol and TD-F(Mw) =TD-F(∞)-KD-F/Mw,where TD-F(∞) =54.7 ℃ and KD-F =27000 ℃·g/mol.Quasi two-dimensional blob models were proposed to provide empirical explanations of the molecular weight dependences.The labyrinthine-to-dendritic transition is attributed to a molecular diffusion process change from a local-diffusion to diffusion-limited-aggregation (DLA) and a polymer chain with Mw ≈ 253000 g/mol within a blob can join crystals independently.The dendritic-to-faceted transition is attributed to a turnover of the pattern formation mechanism from DLA to crystallization control,and a polymer chain with a Mw ≈ 27000g/mol as an independent blob crosses to a depletion zone to join crystals.These molecular weight dependences reveal a macromolecular effect on the crystal pattern formation and selection of crystalline polymers.

  19. EFFECTS OF CONVECTIVE FLUID MOTION UPON OXIDE CRYSTAL GROWTH IN HIGH TEMPERATURE SOLUTION

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ For understanding of the influence of convective flow on crystal growth, space high temperature in situ observation instrument (SHITISOI) is dedicated to visualize and record the whole growth process of oxide crystals in high temperature up to 1000°C. Model experiments using transparent liquids such as KNbO3 and a mix ture of Li2B4O7+KNbO3 were chosen to investigate effects on ground and in space.On the earth, an investigation of growth kinetics of KNbO3 crystal related to two different states of convection: diffusive-advective flow and diffusive-convective flow,has been performed. The per unit length of a step e is calculated from the exper imental data for two different states of convection. Analyses of these data show the effect of buoyancy convection is to enhance the sharpness of the interface. The growth of KNbO3 crystals from solution of KNbO3+Li2B4O7 was investigated in space. The streamlines of the steady thermocapillary convection in Li2B4O7 solvent was observed. Due to thermocapillary convection, KNbO3 crystal grains grew and filled the whole solution homogeneously. Earth-based quenching experiments are de signed in order to study polyhedral instability of KNbO3 crystal, which is controlled by diffusion mechanism limitation. In all cases, when the crystal was nucleated near air/solution surface, it lost its polyhedral stability and varied from polyhedrons to dedrites. The thickness of diffusion mechanism limitation layer is about 60μm.

  20. Physiochemical Characterization of Iodine (V Oxide Part II: Morphology and Crystal Structure of Particulate Films

    Directory of Open Access Journals (Sweden)

    Brian K. Little

    2015-11-01

    Full Text Available In this study, the production of particulate films of iodine (V oxides is investigated. The influence that sonication and solvation of suspended particles in various alcohol/ketone/ester solvents have on the physical structure of spin or drop cast films is examined in detail with electron microscopy, powder x-ray diffraction, and UV-visible absorption spectroscopy. Results indicate that sonicating iodine oxides in alcohol mixtures containing trace amounts of water decreases deposited particle sizes and produces a more uniform film morphology. UV-visible spectra of the pre-cast suspensions reveal that for some solvents, the iodine oxide oxidizes the solvent, producing I2 and lowering the pH of the suspension. Characterizing the crystals within the cast films reveal their composition to be primarily HI3O8, their orientations to exhibit a preferential orientation, and their growth to be primarily along the ac-plane of the crystal, enhanced at higher spin rates. Spin-coating at lower spin rates produces laminate-like particulate films versus higher density, one-piece films of stacked particles produced by drop casting. The particle morphology in these films consists of a combination of rods, plates, cubes, and rhombohedra structure.

  1. Cell adhesion of Shewanella oneidensis to iron oxide minerals: Effect of different single crystal faces

    Directory of Open Access Journals (Sweden)

    Hochella Michael F

    2005-12-01

    Full Text Available The results of experiments designed to test the hypothesis that near-surface molecular structure of iron oxide minerals influences adhesion of dissimilatory iron reducing bacteria are presented. These experiments involved the measurement, using atomic force microscopy, of interaction forces generated between Shewanella oneidensis MR-1 cells and single crystal growth faces of iron oxide minerals. Significantly different adhesive force was measured between cells and the (001 face of hematite, and the (100 and (111 faces of magnetite. A role for electrostatic interactions is apparent. The trend in relative forces of adhesion generated at the mineral surfaces is in agreement with predicted ferric site densities published previously. These results suggest that near-surface structure does indeed influence initial cell attachment to iron oxide surfaces; whether this is mediated via specific cell surface-mineral surface interactions or by more general interfacial phenomena remains untested.

  2. Nanowire-based All Oxide Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang*, Benjamin D. Yuhas and Peidong; Yang, Peidong

    2008-12-07

    We present an all-oxide solar cell fabricated from vertically oriented zinc oxide nanowires and cuprous oxide nanoparticles. Our solar cell consists of vertically oriented n-type zinc oxide nanowires, surrounded by a film constructed from p-type cuprous oxide nanoparticles. Our solution-based synthesis of inexpensive and environmentally benign oxide materials in a solar cell would allow for the facile production of large-scale photovoltaic devices. We found that the solar cell performance is enhanced with the addition of an intermediate oxide insulating layer between the nanowires and the nanoparticles. This observation of the important dependence of the shunt resistance on the photovoltaic performance is widely applicable to any nanowire solar cell constructed with the nanowire array in direct contact with one electrode.

  3. Synthesis, crystal growth and characterization of a chiral compound (triphenylphosphine oxide cadmium iodide): A new semiorganic nonlinear optical material

    Science.gov (United States)

    Santhakumari, R.; Ramamurthi, K.; Stoeckli-Evans, Helen; Hema, R.; Nirmala, W.

    2011-05-01

    Synthesis of semiorganic material, triphenylphosphine oxide cadmium iodide (TPPOCdI), is reported for the first time. Employing the temperature reduction method, a crystal of size 16×7×6 mm 3 was grown from dimethyl sulfoxide (DMSO) solution. Three dimensional crystal structure of the grown crystal was determined by single crystal X-ray diffraction study. The complex crystallizes in the chiral orthorhombic space group P2 12 12 1. FTIR study was carried out in order to confirm the presence of the functional groups. UV-vis-NIR spectral studies show that the crystal is transparent in the wavelength range of 290-1100 nm. The microhardness test was carried out, and the load hardness was measured. Thermogravimetric and differential thermal analyses reveal the thermal stability of the crystal. Second harmonic generation efficiency of the powdered TPPOCdI, tested using Nd: YAG laser, is ∼0.65 times that of potassium dihydrogen orthophosphate.

  4. Crystallization behaviour of poly(ethylene oxide) under confinement in the electrospun nanofibers of polystyrene/poly(ethylene oxide) blends.

    Science.gov (United States)

    Samanta, Pratick; V, Thangapandian; Singh, Sajan; Srivastava, Rajiv; Nandan, Bhanu; Liu, Chien-Liang; Chen, Hsin-Lung

    2016-06-21

    We have studied the confined crystallization behaviour of poly(ethylene oxide) (PEO) in the electrospun nanofibers of the phase-separated blends of polystyrene (PS) and PEO, where PS was present as the major component. The size and shape of PEO domains in the nanofibers were considerably different from those in the cast films, presumably because of the nano-dimensions of the nanofibers and the extensional forces experienced by the polymer solution during electrospinning. The phase-separated morphology in turn influenced the crystallization behaviour of PEO in the blend nanofibers. At a PEO weight fraction of ≥0.3, crystallization occurred through a heterogeneous nucleation mechanism similar to that in cast blend films. However, as the PEO weight fraction in the blend nanofibers was reduced from 0.3 to 0.2, an abrupt transformation of the nucleation mechanism from the heterogeneous to predominantly homogenous type was observed. The change in the nucleation mechanism implied a drastic reduction of the spatial continuity of PEO domains in the nanofibers, which was not encountered in the cast film. The melting temperature and crystallinity of the PEO crystallites developed in the nanofibers were also significantly lower than those in the corresponding cast films. The phenomena observed were reconciled by the morphological observation, which revealed that the phase separation under the radial constraint of the nanofibers led to the formation of small-sized fibrillar PEO domains with limited spatial connectivity. The thermal treatment of the PS/PEO blend nanofibers above the glass transition temperature of PS induced an even stronger confinement effect on PEO crystallization.

  5. Oxygen Barrier Properties and Melt Crystallization Behavior of Poly(ethylene terephthalate/Graphene Oxide Nanocomposites

    Directory of Open Access Journals (Sweden)

    Anna Szymczyk

    2015-01-01

    Full Text Available Poly(ethylene terephthalate nanocomposites with low loading (0.1–0.5 wt% of graphene oxide (GO have been prepared by using in situ polymerization method. TEM study of nanocomposites morphology has shown uniform distribution of highly exfoliated graphene oxide nanoplatelets in PET matrix. Investigations of oxygen permeability of amorphous films of nanocomposites showed that the nanocomposites had better oxygen barrier properties than the neat PET. The improvement of oxygen permeability for PET nanocomposite films over the neat PET is approximately factors of 2–3.3. DSC study on the nonisothermal crystallization behaviors proves that GO acts as a nucleating agent to accelerate the crystallization of PET matrix. The evolution of the lamellar nanostructure of nanocomposite and neat PET was monitored by SAXS during nonisothermal crystallization from the melt. It was found that unfilled PET and nanocomposite with the highest concentration of GO (0.5 wt% showed almost similar values of the long period (L=11.4 nm for neat PET and L=11.5 nm for PET/0.5GO.

  6. Temperature effect on lactose crystallization, maillard reactions, and lipid oxidation in whole milk powder.

    Science.gov (United States)

    Thomsen, Marianne K; Lauridsen, Lene; Skibsted, Leif H; Risbo, Jens

    2005-09-07

    Whole milk powder with an initial water content of 4.4% (w/w) and a water activity of 0.23 stored in hermetically sealed vials for up to 147 days below (37 and 45 degrees C) and above (55 degrees C) the glass transition temperature (T(g) determined to have the value 48 degrees C) showed a strong temperature dependence for quality deterioration corresponding to energies of activation close to 200 kJ/mol for most deteriorative processes. The glass transition was found not to cause any deviation from Arrhenius temperature dependence. Lactose crystallization, which occurred as a gradual process as monitored by isothermal calorimetry, is concluded to liberate bound water (a(w) increase to 0.46) with a modest time delay (approximately 2 days at 55 degrees C) and with concomitant surface browning as evidenced by an increasing Hunter b-value. Browning and formation of bound hydroxymethyl-furfural determined by HPLC seem to be coupled, while formation of another Maillard reaction product, furosine, occurred gradually and was initiated prior to crystallization. Initiation of lipid oxidation, as detected by lipid-derived radicals (high g-value ESR spectra), and progression of lipid oxidation, as detected by headspace GC, seem not to be affected by lactose crystallization and browning, and no indication of browning products acting as antioxidants could be determined.

  7. Synthesis of Distinct Iron Oxide Nanomaterial Shapes Using Lyotropic Liquid Crystal Solvents

    Directory of Open Access Journals (Sweden)

    Seyyed Muhammad Salili

    2017-08-01

    Full Text Available A room temperature reduction-hydrolysis of Fe(III precursors such as FeCl3 or Fe(acac3 in various lyotropic liquid crystal phases (lamellar, hexagonal columnar, or micellar formed by a range of ionic or neutral surfactants in H2O is shown to be an effective and mild approach for the preparation of iron oxide (IO nanomaterials with several morphologies (shapes and dimensions, such as extended thin nanosheets with lateral dimensions of several hundred nanometers as well as smaller nanoflakes and nanodiscs in the tens of nanometers size regime. We will discuss the role of the used surfactants and lyotropic liquid crystal phases as well as the shape and size differences depending upon when and how the resulting nanomaterials were isolated from the reaction mixture. The presented synthetic methodology using lyotropic liquid crystal solvents should be widely applicable to several other transition metal oxides for which the described reduction-hydrolysis reaction sequence is a suitable pathway to obtain nanoscale particles.

  8. Characterization of rhenium oxide films and their application to liquid crystal cells

    Science.gov (United States)

    Cazzanelli, E.; Castriota, M.; Marino, S.; Scaramuzza, N.; Purans, J.; Kuzmin, A.; Kalendarev, R.; Mariotto, G.; Das, G.

    2009-06-01

    Rhenium trioxide exhibits high electronic conductivity, while its open cubic crystal structure allows an appreciable hydrogen intercalation, generating disordered solid phases, with protonic conductivity. Rhenium oxide thin films have been obtained by thermal evaporation of ReO3 powders on different substrates, maintained at different temperatures, and also by reactive magnetron sputtering of a Re metallic target. A comparative investigation has been carried out on these films, by using micro-Raman spectroscopy and x-ray diffraction. Two basic types of solid phases appear to grow in the films: a red metallic HxReO3 compound, with distorted perovskite structures, like in the bulk material, and ordered HReO4 crystals based on tetrahedral perrhenate ions. Because of its conduction properties, the electrical and electro-optical behaviors of ReO3 films deposited on standard indium tin oxide/glass substrate have been tested inside asymmetric nematic liquid crystal cells, showing an appreciable capability of rectification of their electro-optical response, in similar way to tungsten trioxide.

  9. Crystallization Kinetics of a Solid Oxide Fuel Cell Seal Glass by Differential Thermal Analysis

    Science.gov (United States)

    Bansal, Narottam P.; Gamble, Eleanor A.

    2005-01-01

    Crystallization kinetics of a barium calcium aluminosilicate glass (BCAS), a sealant material for planar solid oxide fuel cells, have been investigated by differential thermal analysis (DTA). From variation of DTA peak maximum temperature with heating rate, the activation energy for glass crystallization was calculated to be 259 kJ/mol. Development of crystalline phases on thermal treatments of the glass at various temperatures has been followed by powder x-ray diffraction. Microstructure and chemical composition of the crystalline phases were investigated by scanning electron microscopy and energy dispersive spectroscopic (EDS) analysis. BaSiO3 and hexacelsian (BaAl2Si2O8) were the primary crystalline phases whereas monoclinic celsian (BaAl2Si2O8) and (Ba(x), Ca(y))SiO4 were also detected as minor phases. Needle-shaped BaSiO3 crystals are formed first, followed by the formation of other phases at longer times of heat treatments. The glass does not fully crystallize even after long term heat treatments at 750 to 900 C.

  10. Influence of Oxidation and Reduction Treatments on the Photorefractive Properties of Mg:In:Fe:LiNbO3 Crystals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A series of Mg:In:Fe:LiNbO3 crystals were grown by Czochralski technique; their absorption spectra and photo scattering resistance ability after oxidation or reduction treatment were measured by light spot distortion method, and their response time and exponential gain coefficient were tested by two-beam coupling experiment. Besides, the effective carrier concentration has been calculated. The results showed that the absorption edges of reduced and oxidized crystals are respectively shifted to violet and Einstein compared with those of the growth state crystal. From oxidation state to growth state to reduction state of the samples, the photo scattering resistance ability and response time decrease while the exponential gain coefficient and concentration of effective carriers increase. The reduction treatment was necessary for the Mg:In:Fe:LiNbO3 crystals to enhance their photorefractive properties.

  11. The Effect of Oxidation/Reduction Disposing on Optical Properties of Mg:Fe:Mn:LiNbO3 Crystals

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The congruent tri-doped Mg:Mn:Fe:LiNbO3 crystal has been grown by Czochralski method. Some crystal samples are reduced in Li2CO3 powder at 500 ℃ for 24 hours or oxidized for 10 hours at 1100 ℃ in Nb2O5 powder. Compared with As-grown Mg:Mn:Fe:LiNbO3, the absorption edge in UV-Vis. absorption spectrum of the oxidized sample and the reduced shifts to the violet and the red, respectively. Reduction increases the absorption of crystals in visible light region. In two-wave coupling experiments, the writing time, maximum diffraction efficiency and the erasure time of crystal samples in the same conditions are determined. The results indicate that oxidation and reduction disposing has great effect on the holographic recording properties of these crystals. The reduced crystal exhibits the fastest response time of 160 s among the crystal series. The mechanism of post-disposing effect on the holographic recording properties of Mg:Mn:Fe:LiNbO3 crystals are investigated.

  12. Two types of radicals in whole milk powder. Effect of lactose crystallization, lipid oxidation, and browning reactions.

    Science.gov (United States)

    Thomsen, Marianne K; Lauridsen, Lene; Skibsted, Leif H; Risbo, Jens

    2005-03-09

    Whole milk powder was stored in closed vials at 60 degrees C to induce crystallization of lactose within a short time scale. After an induction period of 3-4 days simultaneous crystallization of lactose, increase of water activity, formation of browning products, and increase of radical content took place. Radicals detected before lactose crystallization were characterized by a narrow ESR spectrum (g = 2.006) and could be depleted by removal of oxygen and therefore were assigned to oxidation processes. Late-stage radicals present after crystallization of lactose gave much wider spectra (g = 2.0048) and were independent of oxygen availability and assigned to late-stage Maillard reaction products. The study indicates that the processes of lactose crystallization, browning, and formation of radical species (g = 2.0048) are strongly coupled, while lipid oxidation is less dependent on the other processes.

  13. Crystal orientation dependent thermoelectric properties of highly oriented aluminum-doped zinc oxide thin films

    KAUST Repository

    Abutaha, Anas I.

    2013-02-06

    We demonstrate that the thermoelectric properties of highly oriented Al-doped zinc oxide (AZO) thin films can be improved by controlling their crystal orientation. The crystal orientation of the AZO films was changed by changing the temperature of the laser deposition process on LaAlO3 (100) substrates. The change in surface termination of the LaAlO3 substrate with temperature induces a change in AZO film orientation. The anisotropic nature of electrical conductivity and Seebeck coefficient of the AZO films showed a favored thermoelectric performance in c-axis oriented films. These films gave the highest power factor of 0.26 W m−1 K−1 at 740 K.

  14. Synthesis and Crystal Structure of Borate Oxide Co3BO5

    Institute of Scientific and Technical Information of China (English)

    张浩; 程文旦; 黄子祥

    2001-01-01

    A mix-charge cation solid-state borate oxide Co3BO5 has beensynthesized and its structure has been determined by single-crystal X-ray methods. It crystallizes in the orthorhombic~space group Pbam with cell parameters a=9.2963(2), b=11.948(2), c=2.9737(6) Å, V=330.30(12)Å3, Z=4, Mr=267.60, F(000)=504, μ=14.733, Dcalcd=5.381g/cm3. The structure was determined from 853 unique reflections and refined to the final residuals R=0.0633 and wR=0.1457. It has two kinds of Co cations, Co2+ and Co3+. It is composed of highly distorted [CoO4] squares and triangular [BO3] groups that are connected to form infinite two-dimensional layers.

  15. Engineering surface atomic structure of single-crystal cobalt (II) oxide nanorods for superior electrocatalysis.

    Science.gov (United States)

    Ling, Tao; Yan, Dong-Yang; Jiao, Yan; Wang, Hui; Zheng, Yao; Zheng, Xueli; Mao, Jing; Du, Xi-Wen; Hu, Zhenpeng; Jaroniec, Mietek; Qiao, Shi-Zhang

    2016-09-21

    Engineering the surface structure at the atomic level can be used to precisely and effectively manipulate the reactivity and durability of catalysts. Here we report tuning of the atomic structure of one-dimensional single-crystal cobalt (II) oxide (CoO) nanorods by creating oxygen vacancies on pyramidal nanofacets. These CoO nanorods exhibit superior catalytic activity and durability towards oxygen reduction/evolution reactions. The combined experimental studies, microscopic and spectroscopic characterization, and density functional theory calculations reveal that the origins of the electrochemical activity of single-crystal CoO nanorods are in the oxygen vacancies that can be readily created on the oxygen-terminated {111} nanofacets, which favourably affect the electronic structure of CoO, assuring a rapid charge transfer and optimal adsorption energies for intermediates of oxygen reduction/evolution reactions. These results show that the surface atomic structure engineering is important for the fabrication of efficient and durable electrocatalysts.

  16. Engineering surface atomic structure of single-crystal cobalt (II) oxide nanorods for superior electrocatalysis

    Science.gov (United States)

    Ling, Tao; Yan, Dong-Yang; Jiao, Yan; Wang, Hui; Zheng, Yao; Zheng, Xueli; Mao, Jing; Du, Xi-Wen; Hu, Zhenpeng; Jaroniec, Mietek; Qiao, Shi-Zhang

    2016-01-01

    Engineering the surface structure at the atomic level can be used to precisely and effectively manipulate the reactivity and durability of catalysts. Here we report tuning of the atomic structure of one-dimensional single-crystal cobalt (II) oxide (CoO) nanorods by creating oxygen vacancies on pyramidal nanofacets. These CoO nanorods exhibit superior catalytic activity and durability towards oxygen reduction/evolution reactions. The combined experimental studies, microscopic and spectroscopic characterization, and density functional theory calculations reveal that the origins of the electrochemical activity of single-crystal CoO nanorods are in the oxygen vacancies that can be readily created on the oxygen-terminated {111} nanofacets, which favourably affect the electronic structure of CoO, assuring a rapid charge transfer and optimal adsorption energies for intermediates of oxygen reduction/evolution reactions. These results show that the surface atomic structure engineering is important for the fabrication of efficient and durable electrocatalysts. PMID:27650485

  17. LETTER TO THE EDITOR: Raman investigation of InSe and GaSe single-crystals oxidation

    Science.gov (United States)

    Balitskii, O. A.; Savchyn, V. P.; Yukhymchuk, V. O.

    2002-02-01

    We discuss the Raman scattering of thermally oxidized gallium selenide (GaSe) and indium selenide (InSe) single crystals. It has been established that the oxidation mechanisms of these compounds are rather different. For InSe, an increase of the oxidation temperature leads to the formation of (SeO4) complexes. For GaSe, it is characteristic that only Ga2O3 is formed as an oxygen-containing phase during the oxidation. The presence of the Me2Se3 phase (where Me is Ga or In) in its own oxide is common for both of the semiconductors.

  18. Tungsten Incorporation into Gallium Oxide: Crystal Structure, Surface and Interface Chemistry, Thermal Stability and Interdiffusion

    Energy Technology Data Exchange (ETDEWEB)

    Rubio, E. J.; Mates, T. E.; Manandhar, S.; Nandasiri, M.; Shutthanandan, V.; Ramana, C. V.

    2016-12-01

    Tungsten (W) incorporated gallium oxide (Ga2O3) (GWO) thin films were deposited by radio-frequency magnetron co-sputtering of W-metal and Ga2O3-ceramic targets. Films were produced by varying sputtering power applied to the W-target in order to achieve variable W-content (0-12 at%) into Ga2O3 while substrate temperature was kept constant at 500 °C. Chemical composition, chemical valence states, microstructure and crystal structure of as-deposited and annealed GWO films were evaluated as a function of W-content. The structural and chemical analyses indicate that the samples deposited without any W-incorporation are stoichiometric, nanocrystalline Ga2O3 films, which crystallize in β-phase monoclinic structure. While GWO films also crystallize in monoclinic β-Ga2O3 phase, W-incorporation induces surface amorphization as revealed by structural studies. The chemical valence state of Ga ions probed by X-ray photoelectron spectroscopic (XPS) analyses is characterized by the highest oxidation state i.e., Ga3+. No changes in Ga chemical state are noted for variable W-incorporation in the range of 0-12 at%. Rutherford backscattering spectrometry (RBS) analyses indicate the uniform distribution of W-content in the GWO films. However, XPS analyses indicate the formation of mixed valence states for W ions, which may be responsible for surface amorphization in GWO films. GWO films were stable up to 900 oC, at which point thermally induced secondary phase (W-oxide) formation was observed. A transition to mesoporous structure coupled with W interdiffusion occurs due to thermal annealing as derived from the chemical analyses at the GWO films’ surface as well as depth-profiling towards the GWO-Si interface. A model has been formulated to account for the mechanism of W-incorporation, thermal stability and interdiffusion via pore formation in GWO films.

  19. Crystal Structure of Oxidative Stress Sensor Keap1 in Complex with Selective Autophagy Substrate p62

    Science.gov (United States)

    Kurokawa, Hirofumi

    Keap1, an adaptor protein of cullin-RING ubiquitin ligase complex, represses cytoprotective transcription factor Nrf2 in an oxidative stress-dependent manner. The accumulation of selective autophagy substrate p62 also activates Nrf2 target genes, but the detailed mechanism has not been elucidated. Crystal structure of Keap1-p62 complex revealed the structural basis for the Nrf2 activation in which Keap1 is inactivated by p62. The accumulation of p62 is observed in hepatocellular carcinoma. The activation of Nrf2 target genes, including detoxifying enzymes and efflux transporters, by p62 may protect the cancer cells from anti-cancer drugs.

  20. Facile synthesis of Graphene Oxide/Double-stranded DNA composite liquid crystals and Hydrogels

    Indian Academy of Sciences (India)

    Rajendra Kurapati; Ashok M Raichur; U Venkateswara Reddy; N Suryaprakash

    2016-03-01

    Investigation of the interactions between graphene oxide (GO) and biomolecules is very crucialfor the development of biomedical applications based on GO. This study reports the first observation of thespontaneous formation of self-assembled liquid crystals and three-dimensional hydrogels of graphene oxidewith double-stranded DNA by simple mixing in an aqueous buffer media without unwinding double-strandedDNA to single-stranded DNA. The GO/dsDNA hydrogels have shown controlled porosity by changing the concentration of the components. The strong binding between dsDNA and graphene is proved by Ramanspectroscopy

  1. Inductive crystal field control in layered metal oxides with correlated electrons

    Energy Technology Data Exchange (ETDEWEB)

    Balachandran, P. V.; Cammarata, A.; Rondinelli, J. M., E-mail: jrondinelli@nortwestern.edu [Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104 (United States); Nelson-Cheeseman, B. B. [School of Engineering, University of St. Thomas, St. Paul, Minnesota 55105 (United States); Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Bhattacharya, A. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2014-07-01

    We show that the NiO{sub 6} crystal field energies can be tailored indirectly via heterovalent A cation ordering in layered (La,A)NiO{sub 4} Ruddlesden–Popper (RP) oxides, where A = Sr, Ca, or Ba, using density functional calculations. We leverage as a driving force the electrostatic interactions between charged [LaO]{sup 1+} and neutral [AO]{sup 0} planes to inductively tune the Ni–O bond distortions, without intentional doping or epitaxial strain, altering the correlated d-orbital energies. We use this strategy to design cation ordered LaCaNiO{sub 4} and LaBaNiO{sub 4} with distortions favoring enhanced Ni e{sub g} orbital polarization, and find local electronic structure signatures analogous to those in RP La-cuprates, i.e., parent phases of the high-temperature superconducting oxides.

  2. Crystallization of the NADH-oxidizing domain of the Na{sup +}-translocating NADH:ubiquinone oxidoreductase from Vibrio cholerae

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Minli [Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich (Switzerland); Türk, Karin [School of Engineering and Science, International University Bremen, 28759 Bremen (Germany); Diez, Joachim [Swiss Light Source at Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Grütter, Markus G. [Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich (Switzerland); Fritz, Günter, E-mail: guenter.fritz@uni-konstanz.de [Fachbereich Biologie, Universität Konstanz, Postfach M665, Universitätsstrasse 10, 78457 Konstanz (Germany); Steuber, Julia, E-mail: guenter.fritz@uni-konstanz.de [Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich (Switzerland)

    2006-02-01

    The FAD domain of the NqrF subunit from the Na{sup +}-translocating NADH dehydrogenase from V. cholerae has been purified and crystallized. A complete data set was recorded at 3.1 Å. The Na{sup +}-translocating NADH:quinone oxidoreductase (Na{sup +}-NQR) from pathogenic and marine bacteria is a respiratory complex that couples the exergonic oxidation of NADH by quinone to the transport of Na{sup +} across the membrane. The NqrF subunit oxidizes NADH and transfers the electrons to other redox cofactors in the enzyme. The FAD-containing domain of NqrF has been expressed, purified and crystallized. The purified NqrF FAD domain exhibited high rates of NADH oxidation and contained stoichiometric amounts of the FAD cofactor. Initial crystallization of the flavin domain was achieved by the sitting-drop technique using a Cartesian MicroSys4000 robot. Optimization of the crystallization conditions yielded yellow hexagonal crystals with dimensions of 30 × 30 × 70 µm. The protein mainly crystallizes in long hexagonal needles with a diameter of up to 30 µm. Crystals diffract to 2.8 Å and belong to space group P622, with unit-cell parameters a = b = 145.3, c = 90.2 Å, α = β = 90, γ = 120°.

  3. Kinetics of Passive Oxidation of Hi-Nicalon-S SiC Fibers in Wet Air: Relationships between Si02 Scale Thickness, Crystallization, and Fiber Strength (Preprint)

    Science.gov (United States)

    2012-07-01

    crystallize to cristobalite and tridymite in 100 hours at 1000°C or in one hour at 1300°C. Crystallization kinetics for oxidation in wet air were...measured by TEM. Oxidation initially produces an amorphous scale that starts to crystallize to cristobalite and tridymite in 100 hours at 1000°C or in...using reflected light interference fringes observed by optical microscopy. Cross-sectional TEM specimens were prepared from oxidized fibers by

  4. Pressure effect on ionic conductivity in yttrium-oxide-doped single-crystal zirconium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Park, E.T.; Park, J.H.

    1998-06-01

    In this study, the authors investigated the effect of pressure on the ionic conductivity of a 9.5 mol% yttria-stabilized zirconia (YSZ) single crystal. The experiment was conducted in the elastic region, and the oxygen ion transport number was unity (t{sub ion} > 0.99999). A conventional four-probe DC method was used to measure the ionic conductivity of the rectangular-shaped sample under uniaxial pressures up to 600 atm at 750 C in air. Measured ionic conductivity decreased as applied pressure increased. Based on henry Eyring`s absolute reaction rate theory, which states that the calculated activation volume has a positive value ({Delta}V{sup 2} = 2.08 cm{sup 3}/mol of O{sup {minus}2}) for oxygen ion transport in the fluoride cubic lattice, they concluded that the results they obtained could be explained by an oxygen ion transport mechanism. This mechanism can explain the fact that the interionic distance increases during oxygen ion transport from one unit cell to neighboring unit cells.

  5. Preparation of silver tin oxide powders by hydrothermal reduction and crystallization

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Silver tin oxide composite powders were synthesized by the hydrothermal method with a silver ammine solution and a Na2SnO3 solution as raw marrials. H2C2O4 was used as the co-precipitator of silver ions and tin ions. The co-precipitation conditions were investigated. The results show that the co-precipitate of Ag2C2O4 and Sn(OH)4 is available when the pH value of the solution is 4.27-8.36. Using the obtained precipitate as precursor, the reduction of Ag+ and the crystallization of tin oxide were carried out simultaneonsly by the hydrothermal method and silver tin oxide composite powders were obtained. The composite powders were characterized by X-ray diffraction (XRD) analysis, scanning electron microscope (SEM), and energy spectrum analysis. The results show that the silver tin oxide composite powders are small with a diameter of about 2 μm and with homogeneous distribution of tin.

  6. The cyclic oxidation behavior of the single crystal TMS-82+ superalloy in humidified air

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y. [School of Materials Science and Engineering, Shanghai, Institute of Technology, Shanghai (China); Research Group of Interface Control Engineering, Graduate School of Engineering, Hokkaido University, Sapporo (Japan); Narita, T. [Research Group of Interface Control Engineering, Graduate School of Engineering, Hokkaido University, Sapporo (Japan)

    2009-10-15

    The cyclic oxidation behavior of a single crystal Ni-based superalloy TMS-82+ was studied at 800 and 900 C for 200 h in water vapor (air plus 15% H{sub 2}O). Regardless of the exposure temperature, time-dependence of the growth rate of the scale for the superalloy was fitted by a subparabolic relationship. The oxidation rate was enhanced with increase in exposure temperature, which was evidenced by a higher mass gain and thicker scale. The oxides on the specimen at 800 C consisted of (Ni,Co)O, CrTaO{sub 4}, AlTaO{sub 4}, Cr{sub 2}O{sub 3}, and {theta}-Al{sub 2}O{sub 3}, whereas for the specimen exposed at 900 C, spinels of NiCr{sub 2}O{sub 4} and (Ni,Co)Al{sub 2}O{sub 4} as well as {alpha}-Al{sub 2}O{sub 3} were observed. An innermost dense {alpha}-Al{sub 2}O{sub 3} layer was responsible for a stable growth rate of the scale after the initial rapid oxidation. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  7. Thermal stimulated current response in cupric oxide single crystal thin films over a wide temperature range

    Science.gov (United States)

    Yang, Kungan; Wu, Shuxiang; Yu, Fengmei; Zhou, Wenqi; Wang, Yunjia; Meng, Meng; Wang, Gaili; Zhang, Yueli; Li, Shuwei

    2017-01-01

    Cupric oxide single crystal thin films (~26 nm) were grown by plasma-assisted molecular beam epitaxy. X-ray diffraction, Raman spectra and in situ reflection high-energy electron diffraction show that the thin films are 2  ×  2 reconstructed with an in-plane compression and out-of-plane stretching. A thermal stimulated current measurement indicates that the electric polarization response is shown in the special 2D cupric oxide single crystal thin film over a wide temperature range from 130 K to near-room temperature. We infer that the abnormal electric response involves the changing of phase transition temperature induced by structure distortion, the spin frustration and the magnetic fluctuation effect of a short-range magnetic order, or the combined action of both of the two factors mentioned above. This work suggests a promising clue for finding new room temperature single phase multiferroics or tuning phase transition temperatures.

  8. Crystal Structure of a Replicative DNA Polymerase Bound to the Oxidized Guanine Lesion Guanidinohydantoin

    Energy Technology Data Exchange (ETDEWEB)

    Aller, Pierre; Ye, Yu; Wallace, Susan S.; Burrows, Cynthia J.; Doubli, Sylvie (Vermont); (Utah)

    2010-04-12

    The oxidation of guanine generates one of the most common DNA lesions, 8-oxo-7,8-dihydroguanine (8-oxoG). The further oxidation of 8-oxoG can produce either guanidinohydantoin (Gh) in duplex DNA or spiroiminodihydantoin (Sp) in nucleosides and ssDNA. Although Gh can be a strong block for replicative DNA polymerases such as RB69 DNA polymerase, this lesion is also mutagenic: DNA polymerases bypass Gh by preferentially incorporating a purine with a slight preference for adenine, which results in G {center_dot} C {yields} T {center_dot} A or G {center_dot} C {yields} C {center_dot} G transversions. The 2.15 {angstrom} crystal structure of the replicative RB69 DNA polymerase in complex with DNA containing Gh reveals that Gh is extrahelical and rotated toward the major groove. In this conformation Gh is no longer in position to serve as a templating base for the incorporation of an incoming nucleotide. This work also constitutes the first crystallographic structure of Gh, which is stabilized in the R configuration in the two polymerase/DNA complexes present in the crystal asymmetric unit. In contrast to 8-oxoG, Gh is found in a high syn conformation in the DNA duplex and therefore presents the same hydrogen bond donor and acceptor pattern as thymine, which explains the propensity of DNA polymerases to incorporate a purine opposite Gh when bypass occurs.

  9. Dense Ge nanocrystal layers embedded in oxide obtained by controlling the diffusion-crystallization process

    Energy Technology Data Exchange (ETDEWEB)

    Lepadatu, Ana-Maria [National Institute of Materials Physics (Romania); Stoica, Toma [Peter Gruenberg Institute (PGI-9), Forschungszentrum Juelich (Germany); Stavarache, Ionel; Teodorescu, Valentin Serban [National Institute of Materials Physics (Romania); Buca, Dan [Peter Gruenberg Institute (PGI-9), Forschungszentrum Juelich (Germany); Ciurea, Magdalena Lidia, E-mail: ciurea@infim.ro [National Institute of Materials Physics (Romania)

    2013-10-15

    Amorphous Ge/SiO{sub 2} multilayer structures deposited by magnetron sputtering have been annealed at different temperatures between 650 and 800 Degree-Sign C for obtaining Ge nanocrystals in oxide matrix. The properties of the annealed structures were investigated by transmission electron microscopy, Raman spectroscopy, and low temperature photoluminescence. The Ge crystallization is partially achieved at 650 Degree-Sign C and increases with annealing temperature. Insight of the Ge nanocrystal formation was acquired by comparing two annealing procedures, i.e., in a conventional tube furnace and by a rapid thermal annealing. By rapid thermal annealing in comparison to conventional furnace one, the Ge crystallization process is faster than Ge diffusion, resulting in the formation of more compact layers of Ge nanocrystals with 8-9.5-nm size as Raman spectroscopy reveals. These findings are important to improve the annealing efficiency in the nanocrystals formation for a precise control of their sizes and location in oxide matrix and for the possibility to create systems with interacting nanoparticles for charge or excitonic transfer. The infrared photoluminescence of Ge nanocrystals at low temperatures shows strong emission with two sharp peaks at about 1,000 meV.

  10. Crystallization and unusual rheological behavior in poly(ethylene oxide)–clay nanocomposites

    KAUST Repository

    Kelarakis, Antonios

    2011-05-01

    We report a systematic study of the crystallization and rheological behavior of poly(ethylene oxide) (PEO)-clay nanocomposites. To that end a series of nanocomposites based on PEOs of different molecular weight (103 < MW < 105 g/mol) and clay surface modifier was synthesized and characterized. Incorporation of organoclays with polar (MMT-OH) or aromatic groups (MMT-Ar) suppresses the crystallization of polymer chains in low MW PEO, but does not significantly affect the crystallization of high MW matrices. In addition, the relative complex viscosity of the nanocomposites based on low MW PEO increases significantly, but the effect is less pronounced at higher MWs. The viscosity increases in the series MMT-Alk < MMT-OH < MMT-Ar. In contrast to the neat PEO which exhibits a monotonic decrease of viscosity with temperature, all nanocomposites show an increase after a certain temperature. This is the first report of such dramatic enhancements in the viscoelasticity of nanocomposites, which are reversible, are based on a simple polymer matrix and are true in a wide temperature range. © 2011 Elsevier Ltd. All rights reserved.

  11. Crystal Structure of Mammalian Cysteine dioxygenase: A Novel Mononuclear Iron Center for Cysteine Thiol Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Simmons,C.; Liu, Q.; Huang, Q.; Hao, Q.; Begley, T.; Karplus, P.; Stipanuk, M.

    2006-01-01

    Cysteine dioxygenase is a mononuclear iron-dependent enzyme responsible for the oxidation of cysteine with molecular oxygen to form cysteinesulfinate. This reaction commits cysteine to either catabolism to sulfate and pyruvate or to the taurine biosynthetic pathway. Cysteine dioxygenase is a member of the cupin superfamily of proteins. The crystal structure of recombinant rat cysteine dioxygenase has been determined to 1.5 Angstroms resolution, and these results confirm the canonical cupin {beta}-sandwich fold and the rare cysteinyl-tyrosine intramolecular crosslink (between Cys93 and Tyr157) seen in the recently reported murine cysteine dioxygenase structure. In contrast to the catalytically inactive mononuclear Ni(II) metallocenter present in the murine structure, crystallization of a catalytically competent preparation of rat cysteine dioxygenase revealed a novel tetrahedrally coordinated mononuclear iron center involving three histidines (His86, His88, and His140) and a water molecule. Attempts to acquire a structure with bound ligand using either co-crystallization or soaks with cysteine revealed the formation of a mixed disulfide involving Cys164 near the active site, which may explain previously observed substrate inhibition. This work provides a framework for understanding the molecular mechanisms involved in thiol dioxygenation and sets the stage for exploring the chemistry of both the novel mononuclear iron center and the catalytic role of the cysteinyl-tyrosine linkage.

  12. Synthesis of 3D ordered macroporous indium tin oxide using polymer colloidal crystal template

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Xue'ao; MAN; Yahui; WANG; Jianfang; LIU; Changli; WU; Wenjian

    2006-01-01

    Three-dimensional (3D) ordered macroporous indium tin oxide (ITO) is prepared using a polymer colloidal crystal template that is formed by self-assembly of the monodisperse poly(methyl methacrylate) (PMMA) microspheres. The morphologies and BET surface area of the macroporous material is examined by scanning electron microscope, transmission electron microscopy and N2 adsorption/desorption. Results indicate that the macroporous material has highly ordered arrays of the uniform pores replicated from the PMMA colloidal crystal template when the polymer colloidal crystal template is removed by calcinations at 500℃. The pore diameter (about 450 nm) of macroporous ITO slightly shrank to the PMMA microspheres. The BET surface area and pore volume of the macroporous material are 389 m2·g-1 and 0.36 cm3·g-1, respectively. Moreover, the macroporous ITO, containing 5 mol% Sn and after annealing under vacuum, shows the minimum resistivity of ρ= 8.2×10-3 Ω· cm. The conductive mechanism of macroporous ITO is discussed, and it is believed that the oxygen vacancies are the major factor for excellent electrical properties.

  13. AFM-tip-induced crystallization of poly(ethylene oxide)melt droplets

    Institute of Scientific and Technical Information of China (English)

    ZHU Dunshen; SHOU Xingxian; LIU Yixin; CHEN Erqiang; Stephen Zhengdi Cheng

    2007-01-01

    The AFM-tip-induced crystallization of poly(ethylene oxide) (PEO) melt droplets was studied.The melt droplets with a height of 50-100 nm and a lateral size of 2-3 pm were obtained by melting the PEO ultra-thin films on a mica surface.For the PEO samples with average molecular weights (Mn) ranging from 1.0×103 g/mol to 1.0×104 g/mol,the lateral perturbation from the AFM tip in the hard-tapping or nanoscratch modes could not induce the growth of the flaton lamellae.In contrast,under AFM nanoindentation mode,the tip-induced crystallization occurred when a sufficiently high vertical tip force was applied to the melt droplets of PEO with Mn≥1.0×104 g/mol. Moreover,the experimental results indicated that the AFM-tip-induced crystallization of PEO in the nanoindentation process had molecular weight dependence.

  14. Synthesis of Quinoxaline 1,4-di-N-Oxide Analogues and Crystal Structure of 2-Carbomethoxy-3-hydroxyquinoxaline-di-N-oxide

    Directory of Open Access Journals (Sweden)

    Minmin Zhang

    2011-08-01

    Full Text Available A series of quinoxaline 1,4-di-N-oxide analogues were prepared from benzofurazan N-oxide derivatives and β-diketone ester compounds by the improved Beirut reaction. The structures of the target products were characterized by NMR, MS, IR and elemental analysis measurements, and that of 2-carbomethoxy-3-hydroxyquinoxaline- di-N-oxide was further confirmed by single-crystal X-ray diffraction. Its crystal structure belongs to the monoclinic system, space group C2/c with a = 14.4320 (12 Å, b = 10.7514 (9 Å, c = 13.2728 (11 Å, V = 1958.5 (3 Å 3, Z = 8. The X-ray crystallographic analysis reveals that quinoxaline 1,4-di-N-oxide displays acyloin-endiol tautomerism.

  15. Theory and experiment on the cuprous-cupric electron transfer rate at a copper electrode.

    Energy Technology Data Exchange (ETDEWEB)

    Halley, J. W.; Smith, B. B.; Walbran, S.; Curtiss, L. A.; Rigney, R. O.; Sutjianto, A.; Hung, N. C.; Yonco, R. M.; Nagy, Z.; Univ. of Minnesota; NREL

    1999-04-01

    We describe results of experiment and theory of the cuprous-cupric electron transfer rate in an aqueous solution at a copper electrode. The methods are similar to those we reported earlier for the ferrous-ferric rate. The comparison strongly suggests that, in marked distinction to the ferrous-ferric case, the electron transfer reaction is adiabatic. The model shows that the activation barrier is dominated by the energy required for the ion to approach the electrode, rather than by the energy required for rearrangement of the solvation shell, also in sharp distinction to the case of the ferric-ferrous electron transfer at a gold electrode. Calculated activation barriers based on this image agree with the experimental results reported here.

  16. Theory and experiment on the cuprous{endash}cupric electron transfer rate at a copper electrode

    Energy Technology Data Exchange (ETDEWEB)

    Halley, J.W. [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Smith, B.B. [National Renewable Energy Laboratory, Golden, Colorado (United States); Walbran, S. [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Curtiss, L.A.; Rigney, R.O.; Sutjianto, A.; Hung, N.C.; Yonco, R.M.; Nagy, Z. [Argonne National Laboratory, Divisions of Materials Science, Chemistry and Chemical Technology, Argonne, Illinois 60439-4837 (United States)

    1999-04-01

    We describe results of experiment and theory of the cuprous{endash}cupric electron transfer rate in an aqueous solution at a copper electrode. The methods are similar to those we reported earlier for the ferrous{endash}ferric rate. The comparison strongly suggests that, in marked distinction to the ferrous{endash}ferric case, the electron transfer reaction is adiabatic. The model shows that the activation barrier is dominated by the energy required for the ion to approach the electrode, rather than by the energy required for rearrangement of the solvation shell, also in sharp distinction to the case of the ferric{endash}ferrous electron transfer at a gold electrode. Calculated activation barriers based on this image agree with the experimental results reported here. {copyright} {ital 1999 American Institute of Physics.}

  17. Physical model construction for electrical anisotropy of single crystal zinc oxide micro/nanobelt using finite element method

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Guangbin [The Higher Educational Key Laboratory for Measuring and Control Technology and Instrumentations of Heilongjiang Province, Harbin University of Science and Technology, Harbin 150080 (China); Tang, Chaolong [Department of Metallurgical and Materials Engineering, Center for Materials for Information Technology (MINT), University of Alabama, Tuscaloosa, Alabama 35487 (United States); Song, Jinhui, E-mail: jhsong@eng.ua.edu, E-mail: wqlu@cigit.ac.cn [The Higher Educational Key Laboratory for Measuring and Control Technology and Instrumentations of Heilongjiang Province, Harbin University of Science and Technology, Harbin 150080 (China); Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714 (China); Department of Metallurgical and Materials Engineering, Center for Materials for Information Technology (MINT), University of Alabama, Tuscaloosa, Alabama 35487 (United States); Lu, Wenqiang, E-mail: jhsong@eng.ua.edu, E-mail: wqlu@cigit.ac.cn [Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714 (China)

    2014-04-14

    Based on conductivity characterization of single crystal zinc oxide (ZnO) micro/nanobelt (MB/NB), we further investigate the physical mechanism of nonlinear intrinsic resistance-length characteristic using finite element method. By taking the same parameters used in experiment, a model of nonlinear anisotropic resistance change with single crystal MB/NB has been deduced, which matched the experiment characterization well. The nonlinear resistance-length comes from the different electron moving speed in various crystal planes. As the direct outcome, crystallography of the anisotropic semiconducting MB/NB has been identified, which could serve as a simple but effective method to identify crystal growth direction of single crystal semiconducting or conductive nanomaterial.

  18. Synthesis and crystal structure investigations of ternary oxides in the Na–Pu–O system

    Energy Technology Data Exchange (ETDEWEB)

    Bykov, D.M., E-mail: d.bykov@tudelft.nl [European Commission, Joint Research Center-Institute for Transuranium Elements, 76125 Karlsruhe (Germany); Raison, P.E., E-mail: philippe.raison@ec.europa.eu [European Commission, Joint Research Center-Institute for Transuranium Elements, 76125 Karlsruhe (Germany); Konings, R.J.M.; Apostolidis, C. [European Commission, Joint Research Center-Institute for Transuranium Elements, 76125 Karlsruhe (Germany); Orlova, M. [University of Innsbruck, Faculty of Geo- and Atmospheric Sciences, A-6020 Innsbruck (Austria)

    2015-02-15

    Highlights: • Crystalline phases in the Na–Pu–O system were obtained by solid state synthesis. • Structures of these phases were studied by the powder X-ray diffraction. • New crystalline forms of Na{sub 5}PuO{sub 5} and Na{sub 3}PuO{sub 4} were observed for the first time. • High-temperature X-ray diffraction studies were performed for Na{sub 4}PuO{sub 5} and Na{sub 5}PuO{sub 6}. • Phase diagram for the ternary Na–Pu–O system was reassessed. - Abstract: Ternary oxides of sodium and plutonium in oxidation states from +4 to +7 have been synthesized by solid state reactions at elevated temperatures in pure argon or oxygen atmospheres. Crystal structures of the obtained phases have been investigated by the Rietveld method using conventional X-ray powder diffraction technique. The structural analogs were found among the families of complex oxides of alkali elements and cerium, ruthenium, antimony, uranium/neptunium and osmium. The new results were compared to earlier literature data for the Na–Pu–O system.

  19. Crystal structure of a mixed-valence μ-oxide Sn12 cluster

    Directory of Open Access Journals (Sweden)

    Marina M. Kireenko

    2014-11-01

    Full Text Available The mixed-valence μ-oxide Sn12 cluster, decacarbonyltetra-μ4-oxido-hexa-μ3-oxido-tetrakis[μ-2,2′-(pyridine-2,6-diylbis(1,1-diphenylethanolato]decatin(IIditin(IVdimolybdenum(O(2 Mo—Sn toluene heptasolvate, [Mo2Sn12(C33H27NO24O10(CO10]·7C7H8, has a crystallographically imposed inversion centre. The asymmetric unit also contains three and a half toluene solvent molecules, one of which is disordered about a centre of symmetry. The complex molecule comprises six distinct Sn atom species with four different coordination numbers, namely 3, 4, 5, and 6. The SnII atoms forming the central Sn10O10 core adopt distorted trigonal–pyramidal, square-pyramidal and octahedral coordination geometries provided by the μ-oxide atoms and by the O- and N-donor atoms of two pyridinediethanolate ligands. The terminal SnIV atoms have distorted trigonal–bipyramidal coordination geometries, with a μ4-oxide atom and the N atom of a pyridinediethanolate ligand occupying the axial positions, and the Mo atom of a Mo(CO5 group and the alkoxy O atoms of a ligand forming the equatorial plane. In the crystal, weak intra- and intermolecular C—H...O hydrogen bonds are observed.

  20. Crystal chemistry of volcanic allanites indicative of naturally induced oxidation-dehydrogenation

    Science.gov (United States)

    Hoshino, Mihoko; Kimata, Mitsuyoshi; Chesner, Craig A.; Nishida, Norimasa; Shimizu, Masahiro; Akasaka, Takeshi

    2010-05-01

    welding of the Youngest Toba Tuff caused the following post-crystallization changes to occur in YTT allanite: oxidation of Fe2+ to Fe3+, release of H2, and the concomitant replacement of OH- by O2-. These oxidation and dehydrogenation processes advanced during the welding to thereby produce oxyallanite. Oxyallanite had been reported only in laboratory studies where it was produced by heating natural allanite. Our report on natural oxyallanite suggests that it may be present in other welded silicic volcanic rocks as well.

  1. Formation of copper oxychloride and reactive oxygen species as causes of uterine injury during copper oxidation of Cu-IUD.

    Science.gov (United States)

    Beltran-Garcia, M J; Espinosa, A; Herrera, N; Perez-Zapata, A J; Beltran-Garcia, C; Ogura, T

    2000-02-01

    The lining of the uterus and cervix might be injured by a variety of oxidation products of Cu in a Cu-IUD, including cuprous ions, dissolved and precipitated cupric ions, and reactive oxygen species such as superoxide radicals, hydrogen peroxide, and hydroxyl radicals. In this study, the human amnious WISH cell line was employed as a model of uterine cells in the presence of copper. The cell viability was decreased by elemental copper, which was alleviated up to 70% by the addition of catalase. The addition of copper oxychloride caused cell death in a dose-dependent manner. Hydroxyl radicals in the presence of copper were determined by the formation of malondialdehyde. Soluble cuprous chloride complexes are formed in the uterus by slowly entering oxygen. The complexes are partly oxidized to insoluble copper oxychloride. which damages the endometrium. Unoxidized cuprous ions migrate to the oxygen-rich cervix and are oxidized to copper oxychloride, causing cervix damage.

  2. Effect of Surface Preparation on the 815°C Oxidation of Single-Crystal Nickel-Based Superalloys

    Science.gov (United States)

    Sudbrack, Chantal K.; Beckett, Devon L.; MacKay, Rebecca A.

    2015-11-01

    A primary application for single-crystal superalloys has been jet engine turbine blades, where operation temperatures reach well above 1000°C. The NASA Glenn Research Center is considering use of single-crystal alloys for future, lower temperature application in the rims of jet engine turbine disks. Mechanical and environmental properties required for potential disk rim operation at 815°C are being examined, including the oxidation and corrosion behavior, where there is little documentation at intermediate temperatures. In this study, single-crystal superalloys, LDS-1101+Hf and CMSX-4+Y, were prepared with different surface finishes and compared after isothermal and cyclic oxidation exposures. Surface finish has a clear effect on oxide formation at 815°C. Machined low-stress ground surfaces after exposure for 440 h produce thin Al2O3 external scales, which is consistent with higher temperature oxidation, whereas polished surfaces with a mirror finish yield much thicker NiO external scales with subscale of Cr2O3-spinel-Al2O3, which may offer less reliable oxidation resistance. Additional experiments separate the roles of cold-work, localized deformation, and the extent of polishing and surface roughness on oxide formation.

  3. Thermal-Mechanical Stability of Single Crystal Oxide Refractive Concentrators for High-Temperature Solar Thermal Propulsion

    Science.gov (United States)

    Zhu, Dongming; Jacobson, Nathan S.; Miller, Robert A.

    1999-01-01

    Single crystal oxides such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium aluminum garnet (Y3Al5O12, or YAG), magnesium oxide (MgO) and sapphire (Al2O3) are candidate refractive secondary concentrator materials for high temperature solar propulsion applications. However, thermo-mechanical reliability of these components in severe thermal environments during the space mission sun/shade transition is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions, and thus provide vital information for the component design. In this paper, a controlled heat flux thermal shock test approach is established for the single crystal oxide materials using a 3.0 kW continuous wave CO2 laser, with a wavelength 10.6 micron. Thermal fracture behavior and failure mechanisms of these oxide materials are investigated and critical temperature gradients are determined under various temperature and heating conditions. The test results show that single crystal sapphire is able to sustain the highest temperature gradient and heating-cooling rate, and thus exhibit the best thermal shock resistance, as compared to the yttria-stabilized zirconia, yttrium aluminum garnet and magnesium oxide.

  4. Electronic and crystal structure analysis of the FeCrO{sub 3} oxide

    Energy Technology Data Exchange (ETDEWEB)

    Ozkendir, Osman Murat, E-mail: ozkendir@gmail.com

    2013-12-15

    Highlights: •The crystal, electronic and magnetic properties of FeCrO{sub 3} compound are investigated. •The measured data were compared with the parent oxides Cr{sub 2}O{sub 3} and Fe{sub 2}O{sub 3}of the compound to identify the structural and electronic change during the process of FeCrO{sub 3} structure. •The electronic properties of the sample were investigated via Fe, Cr L{sub 3,2}and O K-edges and the measurements to probe magnetic properties were performed. •In the FeCrO{sub 3} structure, traces of the O{sub h} and T{sub d} site symmetric local Fe{sup 3+} formations were observed. •The Fe{sup 3+} ions with O{sub h} symmetry as in the parent oxide α-Fe{sub 2}O{sub 3} (hematite) were determined to have antiferromagnetic ordering. -- Abstract: The magnetic and electronic behaviors of FeCrO{sub 3} crystal were investigated by X-ray absorption near edge (XANES) and X-ray magnetic linear dichroism (XMLD) techniques. The measured data were compared with the parent oxides Cr{sub 2}O{sub 3} and α-Fe{sub 2}O{sub 3} of the compound to identify the structural and electronic change during the process of FeCrO{sub 3} structure. The electronic properties of the sample were investigated via Fe, Cr L{sub 3,2} and O K-edges. The XMCD measurements to probe magnetic properties were performed by an external magnetic field of 0.4 T. In the FeCrO{sub 3} structure, traces of the O{sub h} and T{sub d} site symmetric local Fe{sup 3+} formations were observed. The Fe{sup 3+} ions with O{sub h} symmetry as in the parent oxide α-Fe{sub 2}O{sub 3} (hematite) were determined to have antiferromagnetic order in the structure. However, domains who have T{sub d} site symmetry with ferrimagnetic order due to the γ-Fe{sub 2}O{sub 3} (maghemite) formation were determined.

  5. Phase Behavior and Crystal Structure of Perovskite-Type Rare Earth Complex Oxides

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Several compounds of rare earth complex oxides containing manganese and titanium were synthesized in Ar, and their crystal structures were analyzed by powder X-ray diffraction data and Rietveld method. Structures of A0.67Ln0.33Mn0.33Ti0.67O3 (A=Ca or Sr and Ln=rare earth) were found to have orthorhombic symmetry with the space group Pnma, and their interatomic distances and bond angles were obtained. This space group was also derived from electron microscopic study. Electrical conductivity of Ca0.67Ln0.33Mn0.33Ti0.67O3 for several rare earth elements showed a semiconducting property with the activation energy of 0.4 eV. Some of these compounds of the strontium system show the antiferromagnetic properties below 10 K.

  6. Graphene oxide liquid crystals: synthesis, phase transition, rheological property, and applications in optoelectronics and display

    Science.gov (United States)

    Lin, Feng; Tong, Xin; Wang, Yanan; Bao, Jiming; Wang, Zhiming M.

    2015-11-01

    Graphene oxide (GO) liquid crystals (LCs) are macroscopically ordered GO flakes dispersed in water or polar organic solvents. Since the first report in 2011, GO LCs have attracted considerable attention for their basic properties and potential device applications. In this review, we summarize recent developments and present a comprehensive understanding of GO LCs via many aspects ranging from the exfoliation of GO flakes from graphite, to phases and phase transitions under various conditions, the orientational responses of GO under external magnetic and electric fields, and finally Kerr effect and display applications. The emphasis is placed on the unique and basic properties of GO and their ordered assembly. We will also discuss challenges and issues that need to be overcome in order to gain a more fundamental understanding and exploit full device potentials of GO LCs.

  7. Polyelectrolyte-stabilized graphene oxide liquid crystals against salt, pH, and serum.

    Science.gov (United States)

    Zhao, Xiaoli; Xu, Zhen; Xie, Yang; Zheng, Bingna; Kou, Liang; Gao, Chao

    2014-04-08

    Stabilization of colloids is of great significance in nanoscience for their fundamental research and practical applications. Electrostatic repulsion-stabilized anisotropic colloids, such as graphene oxide (GO), can form stable liquid crystals (LCs). However, the electrostatic field would be screened by ions. To stabilize colloidal LCs against electrolyte is an unsolved challenge. Here, an effective strategy is proposed to stabilize GO LCs under harsh conditions by association of polyelectrolytes onto GO sheets. Using sodium poly(styrene sulfonate) (PSS) and poly[2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (PMEDSAH), a kind of polyzwitterion, GO LCs were well-maintained in the presence of NaCl (from 0 M to saturated), extreme pH (from 1 to 13), and serum. Moreover, PSS- or PMEDSAH-coated chemically reduced GO (rGO) also showed stability against electrolyte.

  8. Optical properties of one-dimensional photonic crystals based on porous films of anodic aluminum oxide

    Science.gov (United States)

    Gorelik, V. S.; Klimonsky, S. O.; Filatov, V. V.; Napolskii, K. S.

    2016-04-01

    The optical properties of one-dimensional photonic crystals based on porous anodic aluminum oxide films have been studied by measuring transmittance and specular reflectance spectra in the visible and UV spectral regions. Angular dependences of the spectral positions of optical stop bands are obtained. It is shown that the reflectance within the first stop band varies from point to point on the sample surface, reaching a level of 98-99% at some points. The dispersion relation for electromagnetic waves in the model of infinite periodic structure is calculated for the samples under study. The possibility of using models with an infinite or finite number of layers to calculate reflectance spectra near the first optical stop band is discussed.

  9. Effects of surface crystallization and oxidation in nanocrystalline FeNbCuSiB(P) ribbons

    Science.gov (United States)

    Butvinová, B.; Butvin, P.; Brzózka, K.; Kuzminski, M.; Maťko, I.; Švec, P., Sr.; Chromčíková, M.

    2017-02-01

    Si-poor Fe74Nb3Cu1Si8B14-xPx, (x=0, 3) nanocrystalline ribbon-form alloys often form surfaces, which exert in-plane force on underlying ribbon interior when nanocrystallized in even modest presence of oxygen. Mostly unwanted hard-ribbon-axis magnetic anisotropy is standard result. Essential sources of the surface-caused stress have been sought and influence of P instead of B substitution on this effect was studied too. Preferred surface crystallization (PSC) was found to be the major reason. However P substitution suppresses PSC and promotes Fe-oxide formation, which eases the stress, softens the surfaces and provides different annealing evolution of surface properties.

  10. Crystal structure of a membrane-bound metalloenzyme that catalyses the biological oxidation of methane

    Energy Technology Data Exchange (ETDEWEB)

    Lieberman, R.L.; Rosenzweig, A.C. (NWU)

    2010-03-08

    Particulate methane monooxygenase (pMMO) is an integral membrane metalloenzyme that catalyses the conversion of methane to methanol. Knowledge of how pMMO performs this extremely challenging chemistry may have an impact on the use of methane as an alternative energy source by facilitating the development of new synthetic catalysts. We have determined the structure of pMMO from the methanotroph Methylococcus capsulatus (Bath) to a resolution of 2.8 {angstrom}. The enzyme is a trimer with an {alpha}{sub 3}{beta}{sub 3}{gamma}{sub 3} polypeptide arrangement. Two metal centres, modelled as mononuclear copper and dinuclear copper, are located in soluble regions of each pmoB subunit, which resembles cytochrome c oxidase subunit II. A third metal centre, occupied by zinc in the crystal, is located within the membrane. The structure provides new insight into the molecular details of biological methane oxidation.

  11. Synthesis, characterization, and crystal structure of mercury(II) complex containing new phosphine oxide salt

    Science.gov (United States)

    Samiee, Sepideh; Kooti, Nadieh; Gable, Robert W.

    2017-02-01

    The reaction of new phosphonium-phosphine oxide salt [P(O)Ph2(CH2)2PPh2CH2C(O)C6H4NO2]Br (1) with mercury(II) iodide in a methanolic solution yielded [P(O)Ph2(CH2)2PPh2CH2C(O)C6H4NO2]2[Hg2I5Br](2). These two compounds were fully characterized by elemental analysis, IR, 1H, 31P, and 13C NMR spectra. Crystal and molecular structure of 2 has been determined by means of X-ray diffraction. In mercury compound, the phosphine oxide salt is found as a counter ion letting the mercury(II) ion to bound halides to all four coordination sites and to give dimermercurate(II) ions as the structure-constructing species. The neighboring [P(O)Ph2(CH2)2PPh2CH2C(O)C6H4NO2]2+cations are joined together by intramolecular Csbnd H⋯O hydrogen bonds to give a 1-D chain structure along the crystallographic b-axis. The [Hg2I5Br]2-anions act as cross-linkers between neighbouring strands extending the supramolecular structure into 2D layers in (110) planes as well as balances the charge of the complex. The significant effects of Csbnd H⋯X (Xdbnd O, Br and I) and π⋯π aromatic interactions play a major role in the crystal packing of compound 2.

  12. Factors Affecting the Plasticity of Sodium Chloride, Lithium Fluoride, and Magnesium Oxide Single Crystals. 1

    Science.gov (United States)

    Stearns, Carl A.; Pack, Ann E.; Lad, Robert A.

    1959-01-01

    A study was made of the relative magnitude of the effects of various factors on the ductility of single crystals of sodium chloride (NaCl), lithium fluoride (LiF), and magnesium oxide (MgO). Specimen treatments included water-polishing, varying cleavage rate, annealing, quenching, X-irradiation, surface coating, aging, and combinations of some of these treatments. The mechanical behavior of the crystals was studied in flexure and in compression, the latter study being performed at both constant strain rate and constant load. Etch-pit studies were carried out to provide some pertinent information on the results of pretreatment on the dislocation concentration and distribution in the vicinity of the surface. The load deformation curves for these ionic single crystals show an initial region of very low slope which proved to be due to anelastic deformation. The extent of initial anelastic deformation is modified by specimen pretreatment in a way that suggests that this deformation is the result of expansion of cleaved-in dislocation loops, which can contract on the removal of the stress. The effects of the various pretreatments on the load and deflection at fracture are in accord with the prediction one might make with regard to their effect on the nucleation of fatal surface cracks. For NaCl, increases in ductility are always accompanied by increases in strength. The creep constants for NaCl are a function of treatments which affect the bulk structure but are not a function of treatments which only affect the surface.

  13. Liquid crystal alignment in nanoporous anodic aluminum oxide layer for LCD panel applications.

    Science.gov (United States)

    Hong, Chitsung; Tang, Tsung-Ta; Hung, Chi-Yu; Pan, Ru-Pin; Fang, Weileun

    2010-07-16

    This paper reports the implementation and integration of a self-assembled nanoporous anodic aluminum oxide (np-AAO) film and liquid crystal (LC) on an ITO-glass substrate for liquid crystal display (LCD) panel applications. An np-AAO layer with a nanopore array acts as the vertical alignment layer to easily and uniformly align the LC molecules. Moreover, the np-AAO nanoalignment layer provides outstanding material properties, such as being inorganic with good transmittance, and colorless on ITO-glass substrates. In this application, an LCD panel, with the LC on the np-AAO nanoalignment layer, is successfully implemented on an ITO-glass substrate, and its performance is demonstrated. The measurements show that the LCD panel, consisting of an ITO-glass substrate and an np-AAO layer, has a transmittance of 60-80%. In addition, the LCD panel switches from a black state to a bright state at 3 V(rms), with a response time of 62.5 ms. In summary, this paper demonstrates the alignment of LC on an np-AAO layer for LCD applications.

  14. ELECTRONIC STRUCTURE OF BISMUTH MOLYBDENUM OXIDE SINGLE CRYSTAL Bi0.19MoO3

    Institute of Scientific and Technical Information of China (English)

    XIONG RUI; SHI JING; TANG WU-FENG; TIAN DE-CHENG

    2001-01-01

    Single crystal Bi0. 19MoO3 has been grown by fused salt electrolytic technique. X-ray powder diffraction shows that the unit cell parameters are: a=1.9985nm, b=0.4085nm and c=1.4437nm. The temperature dependence of resistivity demonstrates a semiconductor characteristic. X-ray photoemission spectroscopy studies provide that the valence band of Bi0.19MoO3 are made up of oxygen pπ and the r*, r and σ bonding bands formed by orbital combination. The shoulder at 0.4 eV near the top of valence band may be formed from the non-bonding dxy orbitals of some Mo atoms. The O1s core-electron spectrum reveals the presence of two inequivalent bonds of oxygen ions in Bi0.19MoO3. Bi4f core-level spectrum shows two bonding characters of Bi atoms in bismuth molybdenum oxide single crystals. Mo3d core-level spectrum could be decomposed into two kinds of valence states of molybdenum(Mo+5 and Mo+6).

  15. Colloidal crystals of core-shell type spheres with poly(styrene) core and poly(ethylene oxide) shell.

    Science.gov (United States)

    Okamoto, Junichi; Kimura, Hiroshi; Tsuchida, Akira; Okubo, Tsuneo; Ito, Koichi

    2007-04-15

    Elastic modulus and crystal growth kinetics have been studied for colloidal crystals of core-shell type colloidal spheres (diameter=160-200 nm) in aqueous suspension. Crystallization properties of three kinds of spheres, which have poly(styrene) core and poly(ethylene oxide) shell with different oxyethylene chain length (n=50, 80 and 150), were examined by reflection spectroscopy. The suspensions were deionized exhaustively for more than 1 year using mixed bed of ion-exchange resins. The rigidities of the crystals range from 0.11 to 120 Pa and from 0.56 to 76 Pa for the spheres of n=50 and 80, respectively, and increase sharply as the sphere volume fraction increase. The g factor, parameter for crystal stability, range from 0.029 to 0.13 and from 0.040 to 0.11 for the spheres of n=50 and 80, respectively. These g values indicate the formation of stable crystals, and the values were decreased as the sphere volume fraction increased. Two components of crystal growth rate coefficients, fast and slow, were observed in the order from 10(-3) to 10(1)s(-1). This is due to the secondary process in the colloidal crystallization mechanism, corresponding to reorientation from metastable crystals formed in the primary process and/or Ostwald-ripening process. There are no distinct differences in the structural, kinetic and elastic properties among the colloidal crystals of the different core-shell size spheres, nor difference between those of core-shell spheres and silica or poly(styrene) spheres. The results are very reasonably interpreted by the fact that colloidal crystals are formed in a closed container owing to long-range repulsive forces and the Brownian movement of colloidal spheres surrounded by extended electrical double layers, and their formation is not influenced by the rigidity and internal structure of the spheres.

  16. Real-time imaging of melting and crystallization in poly(ethylene oxide) by atomic force microscopy

    NARCIS (Netherlands)

    Pearce, R.; Vancso, Gyula J.

    1998-01-01

    The processes of melting and crystallization of poly(ethylene oxide) are followed in real time at elevated temperature by atomic force microscopy using a simple hot stage apparatus. Hedritic development at a temperature of 57°C is monitored, including the process of lamellar splaying to yield a

  17. Gas sensitivity and photocatalytic performance of cuprous oxide with novel morphologies

    Science.gov (United States)

    Wu, Ling; Wu, Yulin; Jin, Saijia; Zhang, Lun; Xun, Zhipeng

    2016-10-01

    In this work, Cu2O nanoparticles (NPs) with quasi-spherical and bookmark-like morphologies were successfully synthesized via a new facile solution method. The morphologies of products were characterized to show porous surfaces and the size is as small as approximately 20-50 nm. Given the special morphology, Cu2O NPs exhibited superior gas sensitivity to either ethanol or acetone vapors and strong adsorption abilities and high degradation activities for methyl orange under visible-light irradiation. The investigation provided not only a way of synthesizing Cu2O particles with dozens of nanoscale, but also a way of improving its gas sensitivity and catalytic degradation ability.

  18. Efficient visible-light photocatalytic performance of cuprous oxide porous nanosheet arrays

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xianghua; Wang, Jianqiang [Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Department of Chemistry, Beijing Institute of Technology, Beijing 100081 (China); Zhang, Yihe [Beijing Key Laboratory of Mineral Materials and Utilization of Solid Waste, National Laboratory of Mineral Materials, School of Materials Sciences and Technology, China University of Geosciences, Beijing 100083 (China); Cao, Minhua, E-mail: caomh@bit.edu.cn [Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Department of Chemistry, Beijing Institute of Technology, Beijing 100081 (China)

    2015-10-15

    Graphical Abstract: We demonstrated a facile and efficient process for fabricating Cu{sub 2}O porous nanosheet arrays on Cu mesh. Benefiting from the 1D array structure and porous structure, the as-prepared Cu{sub 2}O sample exhibited significantly improved photocatalytic activity for methyl orange degradation under visible light irradiation. - Highlights: • Cu{sub 2}O porous nanosheet arrays on Cu mesh were synthesized via the facile and efficient process. • The Cu{sub 2}O sample exhibited the 1D array structure and porous nanosheet morphology. • The as-prepared Cu{sub 2}O porous nanosheet arrays exhibited significantly improved photocatalytic activity. - Abstract: One-dimensional nanostructures are of great interest for a wide range of applications. In this work, we demonstrated the fabrication of visible-light-responsive Cu{sub 2}O porous nanosheet arrays. The synthesis involved the growth of Cu(OH){sub 2} nanosheet arrays on Cu mesh by solution-based corrosion and thermal transformation of Cu(OH){sub 2} nanosheet to Cu{sub 2}O porous nanosheets on Cu mesh. Benefiting from the one dimensional array structure and porous structure, the as-prepared Cu{sub 2}O porous nanosheet arrays exhibited significantly improved photocatalytic activity for methyl orange degradation under visible light irradiation.

  19. Light-Induced Reduction of Cuprous Oxide in an Environmental Transmission Electron Microscope

    DEFF Research Database (Denmark)

    Cavalca, Filippo Carlo; Laursen, Anders Bo; Wagner, Jakob Birkedal

    2013-01-01

    . Environmental transmission electron microscopy (ETEM) makes it possible to obtain insight into the local structure, composition and reactivity of catalysts in their working environment, which is of fundamental interest for sustainable energy research and is essential for further material optimization. Herein...

  20. Enormous excitonic effects in bulk, mono- and bi- layers of cuprous halides using many-body perturbation technique

    Science.gov (United States)

    Azhikodan, Dilna; Nautiyal, Tashi

    2017-10-01

    Cuprous halides (CuX with X = Cl, Br, I), intensely studied about four decades ago by experimentalists for excitons, are again drawing attention of researchers recently. Potential of cuprous halide systems for device applications has not yet been fully explored. We go beyond the one-particle picture to capture the two-particle physics (electron-hole interaction to form excitons). We have deployed the full tool kit of many-body perturbation technique, GW approximation + Bethe Salpeter equation, to unfurl the rich excitonic physics of the bulk as well as layers of CuX. The negative spin-orbit contribution at the valence band top in CuCl, compared to CuBr and CuI, is in good agreement with experiments. We note that CuX have exceptionally strong excitons, defying the linear fit (between the excitonic binding energy and band gap) encompassing many semiconductors. The mono- and bi- layers of cuprous halides are predicted to be rich in excitons, with exceptionally large binding energies and the resonance energies in UV/visible region. Hence this work projects CuX layers as good candidates for optoelectronic applications. With advancement of technology, we look forward to experimental realization of CuX layers and harnessing of their rich excitonic potential.

  1. A photonic crystal biosensor assay for ferritin utilizing iron-oxide nanoparticles.

    Science.gov (United States)

    Peterson, Ross D; Cunningham, Brian T; Andrade, Juan E

    2014-06-15

    Iron deficiency anemia afflicts 1 in 3 individuals, mostly women and children worldwide. A novel application using iron-oxide nanoparticles (IONPs) and a photonic crystal (PC) optical biosensor as an immunodiagnostic platform for detection of serum ferritin, a biomarker for iron deficiency, is presented. Human liver ferritin (450 kDa), clinical serum controls, and three commercially available ferritin ELISA tests were used to evaluate the PC biosensor assay in terms of inter- and intra-assay variability, spike-recovery (%), limit of detection (LOD), and matrix effects on binding. For the PC biosensor, signal response from label-free, sandwich with secondary antibody (pAb), and pAb functionalized with iron-oxide nanoparticles (FpAb) assays were detected using the Biomolecular Interaction Detection (BIND) system. Bland-Altman analysis was used to evaluate agreement between expected values for ferritin in control sera and each of the detection platforms. Inter- and intra-assay variability of the PC biosensor were both detection sensitivity of PC biosensors for determination of biomarkers of nutritional status.

  2. Three-dimensional photonic crystal fluorinated tin oxide (FTO) electrodes: synthesis and optical and electrical properties.

    Science.gov (United States)

    Yang, Zhenzhen; Gao, Shanmin; Li, Wei; Vlasko-Vlasov, Vitalii; Welp, Ulrich; Kwok, Wai-Kwong; Xu, Tao

    2011-04-01

    Photovoltaic (PV) schemes often encounter a pair of fundamentally opposing requirements on the thickness of semiconductor layer: a thicker PV semiconductor layer provides enhanced optical density, but inevitably increases the charge transport path length. An effective approach to solve this dilemma is to enhance the interface area between the terminal electrode, i.e., transparent conducting oxide (TCO) and the semiconductor layer. As such, we report a facile, template-assisted, and solution chemistry-based synthesis of 3-dimensional inverse opal fluorinated tin oxide (IO-FTO) electrodes. Synergistically, the photonic crystal structure possessed in the IO-FTO exhibits strong light trapping capability. Furthermore, the electrical properties of the IO-FTO electrodes are studied by Hall effect and sheet resistance measurement. Using atomic layer deposition method, an ultrathin TiO(2) layer is coated on all surfaces of the IO-FTO electrodes. Cyclic voltammetry study indicates that the resulting TiO(2)-coated IO-FTO shows excellent potentials as electrodes for electrolyte-based photoelectrochemical solar cells.

  3. Crystal-chemistry guidelines for noncentrosymmetric A2BO4 Ruddlesden-Popper oxides.

    Science.gov (United States)

    Balachandran, Prasanna V; Puggioni, Danilo; Rondinelli, James M

    2014-01-01

    Noncentrosymmetric (NCS) phases are seldom seen in layered A2BO4 Ruddlesden-Popper (214 RP) oxides. In this work, we uncover the underlying crystallographic symmetry restrictions that enforce the spatial parity operation of inversion and then subsequently show how to lift them to achieve NCS structures. Simple octahedral distortions alone, while impacting the electronic and magnetic properties, are insufficient. We show using group theory that the condensation of two distortion modes, which describe suitable symmetry unique octahedral distortions or a combination of a single octahedral distortion with a "compositional" A or B cation ordering mode, is able to transform the centrosymmetric aristotype into a NCS structure. With these symmetry guidelines, we formulate a data-driven model founded on Bayesian inference that allows us to rationally search for combinations of A- and B-site elements satisfying the inversion symmetry lifting criterion. We describe the general methodology and apply it to 214 iridates with A(2+) cations, identifying RP-structured Ca2IrO4 as a potential NCS oxide, which we evaluate with density functional theory. We find a strong energetic competition between two closely related polar and nonpolar low-energy crystal structures in Ca2IrO4 and suggest pathways to stabilize the NCS structure.

  4. Imaging the oxidation effects of the Fenton reaction on phospholipids at the interface between aqueous phase and thermotropic liquid crystals.

    Science.gov (United States)

    Zhang, Minmin; Jang, Chang-Hyun

    2015-08-01

    The lipid peroxidation process has attracted much attention because of the growing evidence of its involvement in the pathogenesis of age-related diseases. Herein, we report a simple, label-free method to study the oxidation of phospholipids by the Fenton reaction at the interface between an aqueous phase and immiscible liquid crystals (LCs). The different images produced by the orientation of 4-cyano-4'-pentylbiphenyl (5CB) corresponded to the presence or absence of oxidized 1,2-dioleoyl-sn-glycero-3-phospho-rac-(1-glycerol) sodium salt (DOPG). The oxidation effects of the Fenton reaction on DOPG were evaluated by monitoring the orientational response of liquid crystals upon contact with the oxidized DOPG solutions. DOPG was oxidized into chain-changed products containing hydroxy, carbonyl, or aldehyde groups, resulting in the rearrangement of the phospholipid layer. This induced the orientational transition of LCs from homeotropic to planar states; therefore, a dark to bright optical shift was observed. This shift was due to the Fenton reaction preventing DOPG to induce the orientational alignment of LCs at the aqueous/LC interface. We also used an ultraviolet spectrophotometer to confirm the effects of oxidation on phospholipids by the Fenton reaction. Using this simple method, a new approach for investigating phospholipid oxidation was established with high resolution and easy accessibility.

  5. Photoelectric properties of heterostructures based on thermo-oxidated GaSe and InSe crystals

    Energy Technology Data Exchange (ETDEWEB)

    Savchyn, V.P.; Kytsai, V.B. [Lviv Ivan Franko State Univ. (Ukraine). Phys. Dept.

    2000-02-21

    The thermal oxidation processes on cleaved surfaces of GaSe and InSe single crystals in the temperature ranges of 450-700 C and 300-600 C, respectively have been investigated. The photoelectric properties of the obtained heterostructures were studied. It was established that the photoconductivity peculiarities can be explained taking into consideration the nature of surface layers formed under definite conditions such as Ga{sub 2}O{sub 3} (for GaSe) and In{sub 2}(SeO{sub 4}){sub 3} or In{sub 2}O{sub 3} (for InSe) oxide phases for GaSe and InSe correspondingly. It is shown that heterostructure spectral photosensitivity can be varied in a wide range due to definite selection of treatment conditions of gallium and indium monoselenides crystals e.g. temperature and duration of oxidation in air atmosphere. (orig.)

  6. CRYSTALLIZATION AND MELTING OF POLY(ETHYLENE OXIDE) CONFINED IN NANOSTRUCTURED PARTICLES WITH CROSS-LINKED SHELLS OF POLYBUTADIENE

    Institute of Scientific and Technical Information of China (English)

    Wei-ping Gao; Yu Bai; Er-qiang Chen; Qi-feng Zhou

    2005-01-01

    Small fixed aggregates of a poly(ethylene oxide)-block-polybutadiene diblock copolymer (PEO-b-PB) in THF solution were obtained by adding a selective solvent for PB blocks, followed by cross-linking the PB shells. The morphologies of the nanostructured particles with a cross-linked shell were investigated by atomic force microscopy and transmission electron microscopy. The average behaviors of the PEO crystallization and melting confined within the nanostructured particles were studied by using differential scanning calorimetry experiments. For the deeply cross-linked sample (SCL-l), the crystallization of the PEO blocks was fully confined. The individual nanoparticles only crystallized at very low crystallization temperatures (TcS), wherein the homogenous primary nucleation determined the overall crystallization rate. For the lightly cross-linked sample (SCL-2), the confinement effect was Tc dependent. At Tc ≤ 42℃, the crystallization and melting behaviors of SCL-2 were similar to those of the pure PEO-b-PB diblock copolymer. At Tc > 42℃,SCL-2 could form PEO lamellae thicker than those of the pure PEO-b-PB crystallized at the same Tc.

  7. Fiber Strength of Hi Nicalon(TM) S After Oxidation and Scale Crystallization in Si(OH)4 Saturated Steam (Postprint)

    Science.gov (United States)

    2017-02-06

    which did not include any fibers oxidized at temperatures over 1000°C. Oxidation and scale crystallization kinetics were characterized by optical and...Oxidation and scale crystallization kinetics were characterized by optical and transmission electron microscopy. At 700°C and higher, if SiO2...for one hour.15, 28, 29 After desizing the fibers were handled only with tweezers or gloved hands. Five to six 7.5 cm length fiber tows were spread

  8. Crystal Structures of the Nitrite and Nitric Oxide Complexes of Horse Heart Myoglobin

    Energy Technology Data Exchange (ETDEWEB)

    Copeland,D.; Soares, A.; West, A.; Richter-Addo, G.

    2006-01-01

    Nitrite is an important species in the global nitrogen cycle, and the nitrite reductase enzymes convert nitrite to nitric oxide (NO). Recently, it has been shown that hemoglobin and myoglobin catalyze the reduction of nitrite to NO under hypoxic conditions. We have determined the 1.20 Angstroms resolution crystal structure of the nitrite adduct of ferric horse heart myoglobin (hh Mb). The ligand is bound to iron in the nitrito form, and the complex is formulated as Mb{sup III}(ONO{sup -}). The Fe-ONO bond length is 1.94 Angstroms, and the O-N-O angle is 113 degrees. In addition, the nitrite ligand is stabilized by hydrogen bonding with the distal His64 residue. We have also determined the 1.30 Angstroms resolution crystal structures of hh Mb{sup II}NO. When hh Mb{sup II}NO is prepared from the reaction of metMb{sup III} with nitrite/dithionite, the FeNO angle is 144 degrees with a Fe-NO bond length of 1.87 Angstroms. However, when prepared from the reaction of NO with reduced Mb{sup II}, the FeNO angle is 120 degrees with a Fe-NO bond length of 2.13 Angstroms. This difference in FeNO conformations as a function of preparative method is reproducible, and suggests a role of the distal pocket in hh Mb{sup II}NO in stabilizing local FeNO conformational minima.

  9. Superconductivity of an oxide film on the surface of Bi(1-x)Sb(x) alloy single crystals produced by electrochemical oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Alfeev, V.N.; Aminov, B.A.; Brandt, N.B.; Vasina, S.IA.; Damaskin, B.B. (Moskovskii Gosudarstvennyi Universitet, Moscow (USSR))

    1989-10-01

    A study is made of the volt-ampere characteristics of point contacts produced by the mechanical compression of the electrochemically oxidized Bi(1-x)Sb(x) single crystals. Volt-ampere characteristics of the Josephson type have been observed at temperatures below Tc=6-8 K, indicating that the oxide films have superconducting properties at these temperatures. In a magnetic field, Mersereau oscillations, typical of a Josephson transition net, are observed in the contact region. In an external microwave field, the volt-ampere characteristics exhibit a structure related to the occurrence of Shapiro steps.

  10. On the solid phase crystallization of In2O3:H transparent conductive oxide films prepared by atomic layer deposition

    Science.gov (United States)

    Macco, Bart; Verheijen, Marcel A.; Black, Lachlan E.; Barcones, Beatriz; Melskens, J.; Kessels, Wilhelmus M. M.

    2016-08-01

    Hydrogen-doped indium oxide (In2O3:H) has emerged as a highly transparent and conductive oxide, finding its application in a multitude of optoelectronic devices. Recently, we have reported on an atomic layer deposition (ALD) process to prepare high quality In2O3:H. This process consists of ALD of In2O3:H films at 100 °C, followed by a solid phase crystallization step at 150-200 °C. In this work, we report on a detailed electron microscopy study of this crystallization process which reveals new insights into the crucial aspects for achieving the large grain size and associated excellent properties of the material. The key finding is that the best optoelectronic properties are obtained by preparing the films at the lowest possible temperature prior to post-deposition annealing. Electron microscopy imaging shows that such films are mostly amorphous, but feature a very low density of embedded crystallites. Upon post-deposition annealing, crystallization proceeds merely from isotropic crystal grain growth of these embedded crystallites rather than by the formation of additional crystallites. The relatively high hydrogen content of 4.2 at. % in these films is thought to cause the absence of additional nucleation, thereby rendering the final grain size and optoelectronic properties solely dependent on the density of embedded crystallites. The temperature-dependent grain growth rate has been determined, from which an activation energy of (1.39 ± 0.04) eV has been extracted. Finally, on the basis of the observed crystallization mechanism, a simple model to fully describe the crystallization process has been developed. This model has been validated with a numerical implementation thereof, which accurately predicts the observed temperature-dependent crystallization behaviour.

  11. TiO2 crystal facet-dependent antimony adsorption and photocatalytic oxidation.

    Science.gov (United States)

    Song, Jiaying; Yan, Li; Duan, Jinming; Jing, Chuanyong

    2017-06-15

    Anatase TiO2 crystal facets are garnering increasing attention due to their unique surface property. However, no specific linear relationship had been derived between the facet exposed on TiO2 and the surface adsorption capacity as well as photocatalytic performance. This study systematically explored the facet effects on antimony (Sb) adsorption and photocatalytic oxidation using high-index {201} and low-index {101}, {001}, and {100} TiO2. The results suggest that high-index {201} TiO2 exhibits the best Sb(III) adsorption and photocatalytic activity compared to the low-index TiO2. Both the Sb(III) adsorption density and the amount of OH and O2(-) generated in solution were correlated to the magnitude of surface energy on TiO2 facets. Photocatalytically generated OH and O2(-) were responsible for Sb(III) photooxidation as evidenced by radical-trapping experiments. The great contribution of OH was observed only on {201}, not on low-index TiO2. This phenomenon was found to be attributable to the high surface energy on {201}, which enables the generation of a large amount of photogeneration OH to compensate for the fast rate of OH dissipation. Therefore, the predominant participation of OH in Sb(III) photooxidation was only possible on high-index {201} TiO2, which resulted in an enhanced photocatalytic rate. On the other hand, O2(-) dominated the Sb(III) photocatalytic oxidation on low-index TiO2. The intrinsic facet-dependent adsorption and photocatalytic mechanism obtained from this study would be useful for developing TiO2-based environmental technologies.

  12. Dielectric spectroscopy of isotropic liquids and liquid crystal phases with dispersed graphene oxide

    Science.gov (United States)

    Al-Zangana, Shakhawan; Iliut, Maria; Boran, Gökçen; Turner, Michael; Vijayaraghavan, Aravind; Dierking, Ingo

    2016-08-01

    Graphene oxide (GO) flakes of different sizes were prepared and dispersed in isotropic and nematic (anisotropic) fluid media. The dielectric relaxation behaviour of GO-dispersions was examined for a wide temperature (25-60 oC) and frequency range (100 Hz-2 MHz). The mixtures containing GO flakes exhibited varying dielectric relaxation processes, depending on the size of the flakes and the elastic properties of the dispersant fluid. Relaxation frequencies of the GO doped isotropic media, such as isopropanol IPA, were observed to be much lower than the GO doped thermotropic nematic medium 5CB. It is anticipated that the slow relaxation frequencies (~10 kHz) could be resulting from the relaxation modes of the GO flakes while the fast relaxation frequencies (~100 kHz) could indicate strongly slowed down molecular modes of the nematogenic molecules, which are anchored to the GO flakes via dispersion interactions. The relaxation frequencies decreased as the size of the GO flakes in the isotropic solvent was increased. Polarizing microscopy showed that GO flakes with a mean diameter of 10 μm, dispersed in water, formed a lyotropic nematic liquid crystal phase. This lyotropic nematic exhibited the slowest dielectric relaxation process, with relaxation frequencies in the order of 2 kHz, as compared to the GO-isotropic suspension and the GO-doped 5CB.

  13. Optimization of a Liquid Crystal-based Sensory Platform for Monitoring Enzymatic Glucose Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Yibin; Jang, Chang-Hyun [Gachon University, Seongnam (Korea, Republic of)

    2016-05-15

    Managing glucose levels in human blood is extremely important for the treatment of diabetes. Here, an innovative sensory strategy has been developed to monitor the enzymatic activities of glucose and glucose oxidase by using confined liquid crystal (LC) birefringent droplet patterns. Acidic products released during the glucose oxidation process lead to a slight decrease in the pH of aqueous systems that can be monitored by pH-sensitive LC materials. Of the existing pH-sensitive LC materials, dodecanoic acid-doped 4-cyano-4'-pentylbiphenyl is inexpensive and easily adjusted to satisfy the 7.4 ± 0.05 pH requirement of human blood. Moreover, the orientational alignment of capillary-confined pH-responsive LCs can be disrupted at the aqueous/LC interface following a slight decrease in the critical pH of aqueous reaction systems, which results in an optical signal that can be observed with the naked eye by using polarizing optical microscopy. Based on the stable LC droplet patterns generated by the cylindrical confinement system, the functionalized LCs can selectively detect glucose at concentrations as low as 0.1 pM. This study further advances the previously reported LC-based glucose monitoring systems by reducing production costs and instituting a smarter LC sensory design. This improved system shows potential for the use in clinical bioassay applications.

  14. Synthesis and study of oxides and chalcogenides: Thin films and crystals

    Science.gov (United States)

    Park, Sangmoon

    Several types of solid-state inorganic materials are prepared and characterized. By using the SILAR (Successive Ionic Layer Adsorption and Reaction) deposition method in conjunction with hydrothermal dehydration both low-temperature deposition and crystallization of oxide thin films are achieved. Various aspects of new transparent p-type materials are studied by examining both powders and thin films. Delafossite type compounds, CuMO2+delta (M = Ga, Sc, In), are synthesized by unique methods, yielding single-phase materials. The conductivity, mobility, and carrier concentration in BaCu2S2 thin films are described and p-type conductivity in the wide band-gap sulfide fluoride, BaCuSF, is examined. Structural and conducting properties of the various polymorphs of In2Se3 and the related structure of Sb2Te 2Se are considered. Structural characterization and cation ordering in Langasite derivatives, La3SnGa5O14 and La3SnGa3Al2O14, is described. Finally, selected aspects of the synthesis, structural characterization, and luminescence properties of Y3(SiO4)2Cl, Mn:Zn 2SiO4, and Eu:Y6WO12 are summarized.

  15. Tunable Design of Structural Colors Produced by Pseudo-1D Photonic Crystals of Graphene Oxide.

    Science.gov (United States)

    Tong, Liping; Qi, Wei; Wang, Mengfan; Huang, Renliang; Su, Rongxin; He, Zhimin

    2016-07-01

    It is broadly observed that graphene oxide (GO) films appear transparent with a thickness of about several nanometers, whereas they appear dark brown or almost black with thickness of more than 1 μm. The basic color mechanism of GO film on a sub-micrometer scale, however, is not well understood. This study reports on GO pseudo-1D photonic crystals (p1D-PhCs) exhibiting tunable structural colors in the visible wavelength range owing to its 1D Bragg nanostructures. Striking structural colors of GO p1D-PhCs could be tuned by simply changing either the volume or concentration of the aqueous GO dispersion during vacuum filtration. Moreover, the quantitative relationship between thickness and reflection wavelength of GO p1D-PhCs has been revealed, thereby providing a theoretical basis to rationally design structural colors of GO p1D-PhCs. The spectral response of GO p1D-PhCs to humidity is also obtained clearly showing the wavelength shift of GO p1D-PhCs at differently relative humidity values and thus encouraging the integration of structural color printing and the humidity-responsive property of GO p1D-PhCs to develop a visible and fast-responsive anti-counterfeiting label. The results pave the way for a variety of potential applications of GO in optics, structural color printing, sensing, and anti-counterfeiting.

  16. Thermal Mechanical Stability of Single-Crystal-Oxide Refractive Concentrators Evaluated for High-Temperature Solar-Thermal Propulsion

    Science.gov (United States)

    Jacobson, Nathan S.; Jacobson, Nathan S.; Miller, Robert A.

    1999-01-01

    Recently, refractive secondary solar concentrator systems were developed for solar thermal power and propulsion (ref. 1). Single-crystal oxides-such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium aluminum garnet (Y3Al5O12, or YAG), magnesium oxide (MgO), and sapphire (Al2O3)-are candidate refractive secondary concentrator materials. However, the refractive concentrator system will experience high-temperature thermal cycling in the solar thermal engine during the sun/shade transition of a space mission. The thermal mechanical reliability of these components in severe thermal environments is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions. In this research at the NASA Lewis Research Center, a controlled heat flux test approach was developed for investigating the thermal mechanical stability of the candidate oxide. This approach used a 3.0-kW continuous-wave (wavelength, 10.6 mm) carbon dioxide (CO2) laser (ref. 2). The CO2 laser is especially well-suited for single-crystal thermal shock tests because it can directly deliver well-characterized heat energy to the oxide surfaces. Since the oxides are opaque at the 10.6-mm wavelength of the laser beam, the light energy is absorbed at the surfaces rather than transmitting into the crystals, and thus generates the required temperature gradients within the specimens. The following figure is a schematic diagram of the test rig.

  17. Large Scale Laser Crystallization of Solution-based Alumina-doped Zinc Oxide (AZO) Nanoinks for Highly Transparent Conductive Electrode

    Science.gov (United States)

    Nian, Qiong; Callahan, Michael; Saei, Mojib; Look, David; Efstathiadis, Harry; Bailey, John; Cheng, Gary J.

    2015-10-01

    A new method combining aqueous solution printing with UV Laser crystallization (UVLC) and post annealing is developed to deposit highly transparent and conductive Aluminum doped Zinc Oxide (AZO) films. This technique is able to rapidly produce large area AZO films with better structural and optoelectronic properties than most high vacuum deposition, suggesting a potential large-scale manufacturing technique. The optoelectronic performance improvement attributes to UVLC and forming gas annealing (FMG) induced grain boundary density decrease and electron traps passivation at grain boundaries. The physical model and computational simulation developed in this work could be applied to thermal treatment of many other metal oxide films.

  18. Crystallization and preliminary X-ray crystallographic studies of glutaredoxin 2 from Saccharomyces cerevisiae in different oxidation states

    Energy Technology Data Exchange (ETDEWEB)

    Discola, Karen Fulan; Oliveira, Marcos Antonio de; Monteiro Silva, Gustavo [Departamento de Biologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, São Paulo, SP (Brazil); Barcena, José Antonio; Porras, Pablo; Padilla, Alicia [Departamento de Bioquímica y Biología Molecular, Campus de Rabanales, Edificio ‘Severo Ochoa’, Universidad de Córdoba, 14071 Córdoba (Spain); Netto, Luis Eduardo Soares [Departamento de Biologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, São Paulo, SP (Brazil); Guimarães, Beatriz Gomes, E-mail: beatriz@lnls.br [Laboratório Nacional de Luz Síncrotron, CP 6192, CEP 13084-971, Campinas, SP (Brazil); Departamento de Biologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, São Paulo, SP (Brazil)

    2005-04-01

    Glutaredoxin 2 (Grx2) from S. cerevisiae was expressed, purified and crystallized using the hanging-drop vapour-diffusion method. Crystals were obtained from protein treated with t-butyl hydroperoxide and from a sample not submitted to pre-treatment. Both crystals belong to the tetragonal space group P4{sub 1}2{sub 1}2, with very similar unit-cell parameters, and diffraction data were collected to 2.05 and 2.15 Å resolution, respectively. Glutaredoxins are small (9–12 kDa) heat-stable proteins that are highly conserved throughout evolution; the glutaredoxin active site (Cys-Pro-Tyr-Cys) is conserved in most species. Five glutaredoxin genes have been identified in Saccharomyces cerevisiae; however, Grx2 is responsible for the majority of oxidoreductase activity in the cell, suggesting that its primary function may be the detoxification of mixed disulfides generated by reactive oxygen species (ROS). Recombinant Grx2 was expressed in Escherichia coli as a 6×His-tagged fusion protein and purified by nickel-affinity chromatography. Prior to crystallization trials, the enzyme was submitted to various treatments with reducing agents and peroxides. Crystals suitable for X-ray diffraction experiments were obtained from untreated protein and protein oxidized with t-butyl hydroperoxide (10 mM). Complete data sets were collected to resolutions 2.15 and 2.05 Å for untreated and oxidized Grx2, respectively, using a synchrotron-radiation source. The crystals belong to space group P4{sub 1}2{sub 1}2, with similar unit-cell parameters.

  19. Comparison of Poly Aluminum Chloride and Chlorinated Cuprous for Chemical Oxygen Demand and Color Removal from Kashan Textile Industries Company Wastewater

    Directory of Open Access Journals (Sweden)

    Hoseindoost Gh.1 MSPH,

    2016-08-01

    Full Text Available Aims Textile wastewaters are the most important health and environmental problems in Kashan. This research was aimed to compare the poly aluminum chloride and chlorinated cuprous efficiency for removal of Chemical Oxygen Demand (COD and color from Kashan Textile Industries Company wastewater. Materials & Methods This experimental bench scale study in a batch system was conducted on 20 composed wastewater samples collected from Kashan Textile Industries Company raw wastewater. During 5 months, in the beginning of every week a day was selected randomly and in the day a composed sample was taken and studied. PAC at the doses of 10, 20, 30, 40 and 50mg.l-1 and chlorinated cuprous at the doses of 100, 200, 300, 400 and 500mg.l-1 were applied. The optimum pH also optimum concentration of PAC and chlorinated cuprous were determined using Jar test. The data was analyzed by SPSS 16 using descriptive statistics and Fisher Exact test. Findings The average concentration of COD in the raw textile wastewater was 2801.56±1398.29mg.l-1. The average COD concentration has been decreased to 1125.47±797.55mg.l-1. There was a significant difference between the effects of these two coagulants efficiency (p<0.05. The average COD removal efficiency for chlorinated cuprous and PAC was 58.52% and 72.56%, respectively. Also, the average color removal efficiency by chlorinated cuprous and PAC were 17.23 and 64.45%, respectively. Conclusion PAC is more efficient than chlorinated cuprous for both COD and color removal from KTIC wastewater.

  20. THE CRYSTALLIZATION OF POTASSIUM GERMANATE GLASS WITH HIGH CONTENT OF NIOBIUM OXIDE

    Directory of Open Access Journals (Sweden)

    SRĐAN D.MATIJAŠEVIĆ

    2012-03-01

    Full Text Available Potassium germanate glass with molar ratio [GeO2]/[K2O] = 1.2 and Nb2O5 content of 34 mol% have been synthesized by a melt-quenching method. The crystallization behavior under non-isothermal and isothermal crystallization conditions was investigated. The results showed that this glass exposed complex primary crystallization. In the temperature range 800 °C. K10Nb22Ge4O68 and metastable KNbO3 and K4Nb6O17 were formed as secondary phases. The crystallization commenced at T > 640 °C with high homogeneous nucleation rate and spherulite crystal growth morphology. DTA curves recorded for powder samples particle size 0.1 mm showed two exothermic peaks and two endothermic peaks within temperature range of T = 640-1020 °C. The analysis of the dominant crystallization mechanism of powder glass sample and kinetics of crystallization is presented.

  1. Polymer-Ion Interaction Weakens the Strain-Rate Dependence of Extension-Induced Crystallization for Poly(ethylene oxide).

    Science.gov (United States)

    Hu, Tingting; Tian, Nan; Ali, Sarmad; Wang, Zhen; Chang, Jiarui; Huang, Ningdong; Li, Liangbin

    2016-03-01

    The crystallization of poly(ethylene oxide) (PEO)-sodium iodine (NaI) composites is investigated by differential scanning calorimetry (DSC), extensional rheology, and in situ small-angle X-ray scattering (SAXS) with the aim of demonstrating versatile roles played by polymer-ion interactions. In the isothermal quiescent crystallization process, a decrease in the crystal growth rate is observed for PEO-NaI and is attributed to slow chain movement caused by the coordination between cations and polymer. In situ SAXS on extensional flow-induced crystallization (FIC) exhibits enhanced kinetics and orientation for both PEO and PEO-NaI with increasing strain rate. However, an overall weaker strain-rate dependence of FIC is observed for PEO-NaI, which can be interpreted as a synergistic consequence of promoted nucleation under flow and impeded crystal growth by polymer-ion interaction. A possible microscopic mechanism is proposed to account for the experimental observation based on the formation of transient cross-linking points in PEO-NaI and their influence on the entanglement network of polymer under various flow fields. The disclosed strain-rate dependence and various ion effects on the behavior of PEO-salt composites contribute to a comprehensive understanding of polymer-ion solid polyelectrolytes.

  2. Fabrication of cuprous chloride films on copper substrate by chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yu-Ting; Ci, Ji-Wei; Tu, Wei-Chen [Department of Electronic Engineering, College of Electrical Engineering and Computer Science, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Uen, Wu-Yih, E-mail: uenwuyih@ms37.hinet.net [Department of Electronic Engineering, College of Electrical Engineering and Computer Science, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Lan, Shan-Ming [Department of Electronic Engineering, College of Electrical Engineering and Computer Science, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Yang, Tsun-Neng; Shen, Chin-Chang; Wu, Chih-Hung [Institute of Nuclear Energy Research, P.O. Box 3-11, Lungtan 32500, Taiwan (China)

    2015-09-30

    Polycrystalline CuCl films were fabricated by chemical bath deposition (CBD) on a Cu substrate at a low solution temperature of 90 °C. Continuous CuCl films were prepared using the copper (II) chloride (CuCl{sub 2}) compound as the precursor for both the Cu{sup 2+} and Cl{sup −} sources, together with repeated HCl dip treatments. An HCl dip pretreatment of the substrate favored the nucleation of CuCl crystallites. Further, interrupting the film deposition and including an HCl dip treatment of the film growth surface facilitated the deposition of a full-coverage CuCl film. A dual beam (FIB/SEM) system with energy dispersive spectrometry facilities attached revealed a homogeneous CuCl layer with a flat-top surface and an average thickness of about 1 μm. Both the excitonic and biexcitonic emission lines were well-resolved in the 6.4 K photoluminescence spectra. In particular, the free exciton emission line was observable at room temperature, indicating the good quality of the CuCl films prepared by CBD. - Highlights: • Cuprous chloride (CuCl) was prepared on Cu substrate by chemical bath deposition. • HCl dip treatments facilitated the deposition of a full-coverage CuCl film. • A homogeneous elemental distribution was recognized for the deposited CuCl layer. • Excitonic and biexcitonic photoluminescence lines of CuCl films were well-resolved. • The free exciton emission line of CuCl films was observable at room temperature.

  3. Novel doxorubicin loaded PEGylated cuprous telluride nanocrystals for combined photothermal-chemo cancer treatment.

    Science.gov (United States)

    Wang, Xianwen; Ma, Yan; Chen, Huajian; Wu, Xiaoyi; Qian, Haisheng; Yang, Xianzhu; Zha, Zhengbao

    2017-02-06

    Recently, combined photothermal-chemo therapy has attracted great attention due to its enhanced anti-tumor efficiency via synergistic effects. Herein, PEGylated cuprous telluride nanocrystals (PEGylated Cu2Te NCs) were developed as novel drug nanocarriers for combined photothermal-chemo treatment of cancer cells. PEGylated Cu2Te NCs were fabricated through a simple two-step process, comprised of hot injection and thin-film hydration. The as-prepared PEGylated Cu2Te NCs (average diameter of 5.21±1.05nm) showed a noticeable photothermal conversion efficiency of 33.1% and good capacity to load hydrophobic anti-cancer drug. Due to the protonated amine group at low pH, the doxorubicin (DOX)-loaded PEGylated Cu2Te NCs (PEGylated Cu2Te-DOX NCs) exhibited an acidic pH promoted drug release profile. Moreover, a three-parameter model, which considers the effects of drug-carrier interactions on the initial burst release and the sustained release of drug from micro- and nano-sized carriers, was used to gain insight into how pH and laser irradiation affect drug release from PEGylated Cu2Te-DOX NCs. Based on the results from in vitro cell study, PEGylated Cu2Te-DOX NCs revealed remarkably photothermal-chemo synergistic effect to HeLa cells, attributed to both the PEGylated Cu2Te NCs mediated photothermal ablation and enhanced cellular uptake of the drug. Thus, our results encourage the usage of Cu2Te-DOX drug nanocarriers for enhanced treatment of cancer cells by combined photothermal-chemo therapy.

  4. Synthesis of indium oxide cubic crystals by modified hydrothermal route for application in room temperature flexible ethanol sensors

    Energy Technology Data Exchange (ETDEWEB)

    Seetha, M., E-mail: seetha.phy@gmail.com [Department of Physics, SRM University, Kattankulathur, Kancheepuram Dt 603 203 (India); Meena, P. [Department of Physics, PSGR Krishnammal College for Women, Coimbatore 641 046 (India); Mangalaraj, D., E-mail: dmraj800@yahoo.com [DRDO-BU Centre for Life Sciences, Bharathiar University Campus, Coimbatore (India); Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 014 (India); Masuda, Yoshitake [National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560 (Japan); Senthil, K. [School of Advanced Materials Science and Engineering, Sungkyunkwan University (Suwon Campus), Cheoncheon-dong 300, Jangan-gu, Suwon 440-746 (Korea, Republic of)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer For the first time HMT is used in the preparation of indium oxide. Black-Right-Pointing-Pointer HMT itself acts as base for the precursor and results in cubic indium hydroxide. Black-Right-Pointing-Pointer Modified hydrothermal route used for the preparation of cubic indium oxide crystals. Black-Right-Pointing-Pointer As a new approach a composite film synthesized with prepared indium oxide. Black-Right-Pointing-Pointer Film showed good response to ethanol vapours with quick response and recovery times. - Abstract: Indium oxide cubic crystals were prepared by using hexamethylenetetramine and indium chloride without the addition of any structure directing agents. The chemical route followed in the present work was a modified hydrothermal synthesis. The average crystallite size of the prepared cubes was found to be 40 nm. A blue emission at 418 nm was observed at room temperature when the sample was excited with a 380 nm Xenon lamp. This emission due to oxygen vacancies made the material suitable for gas sensing applications. The synthesized material was made as a composite film with polyvinyl alcohol which was more flexible than the films prepared on glass substrates. This flexible film was used as a sensing element and tested with ethanol vapours at room temperature. The film showed fast response as well as recovery to ethanol vapours with a sensor response of about 1.4 for 100 ppm of the gas.

  5. Structure and Properties of Reduced Barium Niobium Oxide Single Crystals Obtained from Borate Fluxes

    NARCIS (Netherlands)

    Hessen, B.; Sunshine, S.A.; Siegrist, T.; Fiory, A.T.; Waszczak, J.V.

    1991-01-01

    Single crystals of the reduced niobate Ba2Nb15O32 are produced by heating NbO2 in BaO·3B2O3 under high-vacuum conditions. The borate acts both as a source of BaO and as a flux for crystallization. The compound Ba2Nb15O32 crystallizes in space group R3 (a = 7.777 (1) Å, c = 35.518 (6) Å) and contains

  6. Electrochemical synthesis and characterization of copper (I oxide

    Directory of Open Access Journals (Sweden)

    Bugarinović Sanja J.

    2009-01-01

    Full Text Available The quest and need for clean and economical energy sources have increased interest in the development of thin film cells technologies. Electrochemical deposition is an attractive method for synthesis of thin films. It offers the advantages of low synthesis temperature, low cost and high purity. Copper (I oxide or cuprous oxide is an oxide semiconductor which is used as the anodic material in the form of thin film in lithium batteries and solar cells. The cathodic process of synthesis of cuprous oxide thin film is carried out in a potentiostatic mode from the organic electrolyte. The process parameters are chosen in that way to accomplish maximum difference between the potentials at which Cu2O and CuO are obtained. The electrochemical characterization was carried out by cyclic voltammetry. The electrodeposition techniques are particularly well suited for the deposition of single elements but it is also possible to carry out simultaneous depositions of several elements and syntheses of well-defined alternating layers of metals and oxides with thicknesses down to a few nm. Nanomaterials exhibit novel physical properties and play an important role in fundamental research. In addition, cuprous oxide is commonly used as a pigment, a fungicide, and an antifouling agent for marine paints. It is insoluble in water and organic solvents. This work presents the examinations of the influence of bath, temperature, pH and current density on the characteristics of electrochemically synthesized cuprous oxide. In the 'classic' process of synthesis, which is carried out under galvanostatic conditions on the anode, the grain size of the powder decreases with the increase in current density while the grain colour becomes lighter. The best commercial quality of the Cu2O (grain size, colour, content of choride was obtained at the temperature of 80°C, concentration of NaCl of 3 mol/dm3 and current density of 400 A/m2.

  7. The Improvement of Oxidation Resistance of a Re-Based Diffusion Barrier/Ni–Al Coating on the Single-Crystal Ni-Based TMS-82+ Superalloy

    NARCIS (Netherlands)

    Wu, Y.; Wang, Y.M.; Song, G.M.; Li, X.W.

    2011-01-01

    Oxidation behavior of a Re-based diffusion barrier/Ni–Al coated single-crystal (SC) Ni-based TMS-82+ superalloy was studied to compare with those of the base and Ni–Al coated superalloys under cyclic air at 1150 °C for 200 h. The base superalloy showed a negative mass gain due to extensive oxide spa

  8. Improvement of the Oxidation Resistance of the Single-Crystal Ni-Based TMS-82+ Superalloy by Ni–Al Coatings with/without the Diffusion Barrier

    NARCIS (Netherlands)

    Wu, Y.; Li, X.W.; Song, G.M.; Wang, Y.M.; Narita, T.

    2010-01-01

    Oxidation behavior of the uncoated base, Ni–Al coated and Re–Cr-Ni plus Ni–Al coated single-crystal (SC) Ni-based TMS-82+ superalloy is studied under cyclic air at 900ºC for 200 h to assess the oxidation resistance. Regardless of the coating processing, Ni–Al coating is effective in improving the ox

  9. Correlation between steady-oscillatory flow transition and the interface inversion process during the Czochralski growth of semitransparent oxide crystal

    Science.gov (United States)

    Faiez, Reza; Rezaei, Yazdan

    2016-12-01

    In this paper, steady-oscillatory transition of the convective flow in a Czochralski (Cz) growth system was numerically studied. In this configuration, rapid variations in density across narrow region of the flow in the vicinity of the crystallization front leads to an unstable stratification of the flow in this region. Time-dependent, finite volume method calculation of the momentum and heat transport equations shows that an instability mechanism, giving rise to the formation of cold plumes beneath the phase boundary, might be associated with an irreversible change in the convexity of the front. Dynamics of the crystallization front was found to be correlated with the periodic oscillation of the flow. It was shown that the interface inversion process occurs at a critical Reynolds number significantly (˜25%) lower than that predicted by the steady-state Cz-oxide model analysis. Consistently, the time-averaged maximum value of stream function was found to be larger than its corresponding steady-state value. This indicates that the mechanism behind the oscillatory transition of the flow has a positive feedback on the intensity of forced convection flow. These numerical results were attributed to the baroclinic instability mechanism characterized by oscillations of a cold plume appearing at the crystal periphery and descending along the symmetry axis. The time period of oscillations was found to be considerably (30-40%) decreases and, simultaneously, the inclination angle of isopycnals increases (˜48%) at a critical rotation rate of the crystal for which the interface inversion occurs.

  10. Crystal-chemical and physicochemical properties of complex cadmium oxides with pyrochlore and columbite type of structure

    Energy Technology Data Exchange (ETDEWEB)

    Samigullina, R.F., E-mail: rina@ihim.uran.ru [Russian Academy of Sciences, Ural Branch, Institute of Solid State Chemistry, Ekaterinburg 620990 (Russian Federation); Krasnenko, T.I.; Rotermel, M.V.; Tyutyunnik, A.P. [Russian Academy of Sciences, Ural Branch, Institute of Solid State Chemistry, Ekaterinburg 620990 (Russian Federation); Titova, S.G.; Fedorova, O.M. [Russian Academy of Sciences, Ural Branch, Institute of Metallurgy, Ekaterinburg 620016 (Russian Federation)

    2015-11-15

    Single-phase samples of cadmium pyroniobate and metaniobate were successfully prepared by solid-state synthesis. The crystal structures of cadmium niobates were refined by full-profile fitting of X-ray powder diffraction patterns. The thermal behavior of cadmium niobates in air was studied by thermogravimetric (TG), differential thermal analysis (DTA) and X-ray powder diffraction at elevated temperatures. Found that CdNb{sub 2}O{sub 6} is stable in air up to 1150 °C, Cd{sub 2}Nb{sub 2}O{sub 7} – up to 1120 °C. Above these temperatures these niobates undergoes a solid state decay with volatilization of cadmium oxide, resulting in formation of metaniobate CdNb{sub 2}O{sub 6} from Cd{sub 2}Nb{sub 2}O{sub 7}, and niobium oxide Nb{sub 2}O{sub 5} from CdNb{sub 2}O{sub 6}. - Highlights: • The crystal structures of cadmium niobates were refined. • Linear thermal expansion coefficients of cadmium niobates Cd{sub 2}Nb{sub 2}O{sub 7} and CdNb{sub 2}O{sub 6} were determined. • The limits of thermal stability of both oxides in the air were found.

  11. Alignment of liquid crystal molecules on solution-derived zinc-tin-oxide films via ion beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hong-Gyu; Jeong, Hae-Chang; Lee, Ju Hwan; Jang, Sang Bok [Information Display Device Laboratory, Department of Electrical and Electronic Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul, 120-749 (Korea, Republic of); Oh, Byeong-Yun [ZeSHTech Co., Ltd., Business Incubator, Gwangju Institute of Science and Technology, 123, Cheomdangwagi-ro, Buk-gu, Gwangju, 500-712 (Korea, Republic of); Han, Jeong-Min [Department of Electronic, Seoil University, Jungnang-gu, Seoul, 131-702 (Korea, Republic of); Seo, Dae-Shik, E-mail: dsseo@yonsei.ac.kr [Information Display Device Laboratory, Department of Electrical and Electronic Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul, 120-749 (Korea, Republic of)

    2016-04-15

    We present the characteristics of annealing temperature-dependent, zinc-tin-oxide (ZTO) films deposited by a solution process for application in liquid crystal displays (LCDs). ZTO surfaces supported homogeneously-aligned liquid crystal (LC) molecules based on an ion beam irradiation system. Uniform LC alignment and a precise pretilt angle were obtained at an annealing temperature greater than 300 °C. The oxidation of ZTO films was confirmed using field-emission-scanning electron microscopy and X-ray photoelectron spectroscopy. The electro-optical characteristics of electrically controlled birefringence (ECB) cells based on the ZTO films were superior to those based on polyimide. Especially, IB-irradiated ZTO films exhibited superior performance with respect to response time. This result indicates that this approach will allow for the fabrication of advanced LCDs with high performance. - Highlights: • ZTO alignment films were deposited by a solution process on ITO-coated glass. • Uniform and homogeneous LC alignment was achieved on the IB-irradiated ZTO surface. • Oxidation of ZTO films was confirmed using FESEM and XPS analysis. • Enhanced EO characteristics of ECB cells based on ZTO films were achieved.

  12. Computer simulation of spatial coupling in chemical oscillations of CO oxidation on two Pd(110) single crystals

    Science.gov (United States)

    Park, I. J.; Woo, S. I.

    1993-09-01

    Gas-phase coupling between two Pd(110) single crystals in a UHV CO oxidation reaction in a continuous stirred tank reactor (CSTR) has been simulated by solving gas-phase mass balance equations with kinetic rate equations. This work was motivated by the experimental results which show that the frequency of partial pressure change in carbon monoxide is the same as the frequency of the work function change in the oscillation region and that the coupling between the two crystals occurred entirely via CO partial pressure. The computer simulation described here gives qualitative agreement with the experimental results. The change in the oscillatory region originating from the coupling of chemical oscillators which are slightly different to each other is successfully demonstrated by this model. The coupling of two oscillators having a simple periodic oscillation to produce mixed-mode oscillation was also successfully simulated.

  13. Electrochemical Deposition of Zinc Oxide Crystal Whiskers%电化学法沉积氧化锌晶须

    Institute of Scientific and Technical Information of China (English)

    芦鹏曾; 李素; 贾金乾; 梁镇海

    2011-01-01

    Pine needle ZnO crystal whiskers were electrodeposited by anodization of zinc foil. The crystal whiskers were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) spectroscopy. The results show that the lengths and diameters of ZnO crystal whiskers are 200 ~ 300 nm and 20 ~ 50 nm,respectively,with the ratio of the length to diameter ranging from 10 ~ 15. The whiskers belong to wurtzite ZnO ( JCPDS 36-1451 ) with good crystallinity and high purity. The crystalization behavior of ZnO was studied by cyclic voltammetry. The effects of the surface oxide layer at the zinc substrates and the [Zn( OH)4]2- concentration of the aqueous electrolyte on the formation of zinc oxide whiskers were investigated.%应用阳极氧化法沉积氧化锌(ZnO)松针状晶须,SEM和XRD观察、表征样品形貌与结构.结果表明,电沉积氧化锌晶须直径为20~50 nm、长度200~300nm、长径比10~15,纯度高,结晶度好,属六方晶系纤锌矿(JCPDS 36-1451).循环伏安法研究了该氧化锌结晶过程,并考察了电解液的锌酸盐[Zn(OH)4]2-浓度和基底表面氧化膜对晶须生成的影响.

  14. Crystal Structure of Reduced and of Oxidized Peroxiredoxin IV Enzyme Reveals a Stable Oxidized Decamer and a Non-disulfide-bonded Intermediate in the Catalytic Cycle*

    Science.gov (United States)

    Cao, Zhenbo; Tavender, Timothy J.; Roszak, Aleksander W.; Cogdell, Richard J.; Bulleid, Neil J.

    2011-01-01

    Peroxiredoxin IV (PrxIV) is an endoplasmic reticulum-localized enzyme that metabolizes the hydrogen peroxide produced by endoplasmic reticulum oxidase 1 (Ero1). It has been shown to play a role in de novo disulfide formation, oxidizing members of the protein disulfide isomerase family of enzymes, and is a member of the typical 2-Cys peroxiredoxin family. We have determined the crystal structure of both reduced and disulfide-bonded, as well as a resolving cysteine mutant of human PrxIV. We show that PrxIV has a similar structure to other typical 2-Cys peroxiredoxins and undergoes a conformational change from a fully folded to a locally unfolded form following the formation of a disulfide between the peroxidatic and resolving cysteine residues. Unlike other mammalian typical 2-Cys peroxiredoxins, we show that human PrxIV forms a stable decameric structure even in its disulfide-bonded state. In addition, the structure of a resolving cysteine mutant reveals an intermediate in the reaction cycle that adopts the locally unfolded conformation. Interestingly the peroxidatic cysteine in the crystal structure is sulfenylated rather than sulfinylated or sulfonylated. In addition, the peroxidatic cysteine in the resolving cysteine mutant is resistant to hyper-oxidation following incubation with high concentrations of hydrogen peroxide. These results highlight some unique properties of PrxIV and suggest that the equilibrium between the fully folded and locally unfolded forms favors the locally unfolded conformation upon sulfenylation of the peroxidatic cysteine residue. PMID:21994946

  15. Influence of rare earth oxides on the non-isothermal crystallization of phosphosilicate melts during cooling

    DEFF Research Database (Denmark)

    Liu, S.J.; Shan, Z.T.; Fu, G.Z.;

    2014-01-01

    We report a detailed calorimetric study concerning the influence of Yb2O3 and Er2O3 on the non-isothermal crystallization in phosphosilicate melts. The results show that Yb3+/Er3+ ions promote the Zn2SiO4 crystal formation, but suppress the Na3PO4 and AlPO4 formation during cooling. The non......-isothermal melt-crystallization kinetics can be well described by the Avrami model. The activation energy Ee of crystallization in both the undoped and Yb3+/Er3+ codoped samples during cooling is determined using the differential iso-conversional method of Friedman. The Ee value decreases with crystallinity (θ...

  16. Crystallization of oxidized, moderately hydrous arc basalt at mid- to lower-crustal pressures: Implications for andesite genesis

    Science.gov (United States)

    Blatter, Dawnika L.; Sisson, Thomas W.; Hankins, W. Ben

    2013-01-01

    This study focuses on the production of convergent margin calc-alkaline andesites by crystallization–differentiation of basaltic magmas in the lower to middle crust. Previous experimental studies show that dry, reduced, subalkaline basalts differentiate to tholeiitic (high Fe/Mg) daughter liquids, but the influences of H2O and oxidation on differentiation are less well established. Accordingly, we performed crystallization experiments at controlled oxidized fO2 (Re–ReO2 ≈ ΔNi–NiO + 2) on a relatively magnesian basalt (8.7 wt% MgO) typical of mafic magmas erupted in the Cascades near Mount Rainier, Washington. The basalt was synthesized with 2 wt% H2O and run at 900, 700, and 400 MPa and 1,200 to 950 °C. A broadly clinopyroxenitic crystallization interval dominates near the liquidus at 900 and 700 MPa, consisting of augite + olivine + orthopyroxene + Cr-spinel (in decreasing abundance). With decreasing temperature, plagioclase crystallizes, Fe–Ti-oxide replaces spinel, olivine dissolves, and finally amphibole appears, producing gabbroic and then amphibole gabbroic crystallization stages. Enhanced plagioclase stability at lower pressure narrows the clinopyroxenitic interval and brings the gabbroic interval toward the liquidus. Liquids at 900 MPa track along Miyashiro’s (Am J Sci 274(4):321–355, 1974) tholeiitic versus calc-alkaline boundary, whereas those at 700 and 400 MPa become calc-alkaline at silica contents ≥56 wt%. This difference is chiefly due to higher temperature appearance of magnetite (versus spinel) at lower pressures. Although the evolved liquids are similar in many respects to common calc-alkaline andesites, the 900 and 700 MPa liquids differ in having low CaO concentrations due to early and abundant crystallization of augite, with the result that those liquids become peraluminous (ASI: molar Al/(Na + K + 2Ca) > 1) at ≥61 wt% SiO2, similar to liquids reported in other studies of the high-pressure crystallization of hydrous basalts

  17. Toxicity of iron-based nanoparticles to green algae: Effects of particle size, crystal phase, oxidation state and environmental aging.

    Science.gov (United States)

    Lei, Cheng; Zhang, Luqing; Yang, Kun; Zhu, Lizhong; Lin, Daohui

    2016-11-01

    With the increasing environmental application and discharge of iron-based nanoparticles (NPs), a comprehensive understanding of their fate and ecotoxicological effect in the aquatic environment is very urgent. In this study, toxicities of 4 zero-valent iron NPs (nZVI) of different sizes, 2 Fe2O3 NPs of different crystal phases, and 1 type of Fe3O4 NPs to a green alga (Chlorella pyrenoidosa) were investigated, with a focus on the effects of particle size, crystal phase, oxidation state, and environmental aging. Results show that the algal growth inhibition of nZVI increased significantly with decreasing particle size; with similar particle sizes (20-30 nm), the algal growth inhibition decreased with oxidation of the NPs with an order of nZVI > Fe3O4 NPs > Fe2O3 NPs, and α-Fe2O3 NPs presented significantly higher toxicity than γ-Fe2O3 NPs. The NP-induced oxidative stress was the main toxic mechanism, which could explain the difference in algal toxicity of the NPs. The NP-cell heteroagglomeration and physical interactions also contributed to the nanotoxicity, whereas the effect of NP dissolution was negligible. The aging in distilled water and 3 surface water samples for 3 months increased surface oxidation of the iron-based NPs especially nZVI, which decreased the toxicity to algae. These findings will be helpful for the understanding of the fate and toxicity of iron-based NPs in the aquatic environment.

  18. Crystal structures of human Ero1α reveal the mechanisms of regulated and targeted oxidation of PDI.

    Science.gov (United States)

    Inaba, Kenji; Masui, Shoji; Iida, Hiroka; Vavassori, Stefano; Sitia, Roberto; Suzuki, Mamoru

    2010-10-06

    In the endoplasmic reticulum (ER) of eukaryotic cells, Ero1 flavoenzymes promote oxidative protein folding through protein disulphide isomerase (PDI), generating reactive oxygen species (hydrogen peroxide) as byproducts. Therefore, Ero1 activity must be strictly regulated to avoid futile oxidation cycles in the ER. Although regulatory mechanisms restraining Ero1α activity ensure that not all PDIs are oxidized, its specificity towards PDI could allow other resident oxidoreductases to remain reduced and competent to carry out isomerization and reduction of protein substrates. In this study, crystal structures of human Ero1α were solved in its hyperactive and inactive forms. Our findings reveal that human Ero1α modulates its oxidative activity by properly positioning regulatory cysteines within an intrinsically flexible loop, and by fine-tuning the electron shuttle ability of the loop through disulphide rearrangements. Specific PDI targeting is guaranteed by electrostatic and hydrophobic interactions of Ero1α with the PDI b'-domain through its substrate-binding pocket. These results reveal the molecular basis of the regulation and specificity of protein disulphide formation in human cells.

  19. Oxide-assisted crack growth in hold-time low-cycle-fatigue of single-crystal superalloys

    Directory of Open Access Journals (Sweden)

    Suzuki Akane

    2014-01-01

    Full Text Available Compressive hold-time low-cycle fatigue is one of the important damage modes in Ni-based superalloy hot-gas path components. In strain controlled LCF, the compressive hold typically degrades fatigue life significantly due to creep relaxation and the resultant generation of tensile stress upon returning to zero strain. Crack initiation typically occurs on the surface, and therefore, the cracks are covered with layers of oxides. Recent finite element modeling based on experimental observations has indicated that the in-plane compressive stress in the alumina layer formed on the surface of the bond coat assists rumpling and, eventually, leads to initiation of cracks. The stress in the oxide layer continues to assist crack extension by pushing the alumina layer along the crack front during the compressive hold. In-situ measurements of the growth strains of alumina were performed using high energy synchrotron X-rays at Argonne National Lab. Specimens of single-crystal superalloys with and without aluminide coatings were statically pre-oxidized to form a layer of alumina at 1093 and 982 ∘C. For the in-situ synchrotron measurements, the specimens were heated up to the pre-oxidation temperatures with a heater. The alumina layers on both bare and coated specimens show compressive in-plane strains at both temperatures. The oxide strains on the superalloys showed dependency on temperature; on the other hand, the oxide strains in the aluminide coatings were insensitive to temperature. The magnitude of the compressive strains was larger on the superalloys than the ones on the aluminide coatings.

  20. Surface Binding and Organization of Sensitizing Dyes on Metal Oxide Single Crystal Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Parkinson, Bruce

    2010-06-04

    Even though investigations of dye-sensitized nanocrystalline semiconductors in solar cells has dominated research on dye-sensitized semiconductors over the past two decades. Single crystal electrodes represent far simpler model systems for studying the sensitization process with a continuing train of studies dating back more than forty years. Even today single crystal surfaces prove to be more controlled experimental models for the study of dye-sensitized semiconductors than the nanocrystalline substrates. We analyzed the scientific advances in the model sensitized single crystal systems that preceded the introduction of nanocrystalline semiconductor electrodes. It then follows the single crystal research to the present, illustrating both their striking simplicity of use and clarity of interpretation relative to nanocrystalline electrodes. Researchers have employed many electrochemical, photochemical and scanning probe techniques for studying monolayer quantities of sensitizing dyes at specific crystallographic faces of different semiconductors. These methods include photochronocoulometry, electronic spectroscopy and flash photolysis of dyes at potential-controlled semiconductor electrodes and the use of total internal reflection methods. In addition, we describe the preparation of surfaces of single crystal SnS2 and TiO2 electrodes to serve as reproducible model systems for charge separation at dye sensitized solar cells. This process involves cleaving the SnS2 electrodes and a photoelectrochemical surface treatment for TiO2 that produces clean surfaces for sensitization (as verified by AFM) resulting in near unity yields for electron transfer from the molecular excited dyes into the conduction band.

  1. Fabrication of silica/zinc oxide core-shell colloidal photonic crystals

    Science.gov (United States)

    Ma, Xiying; Shi, Weilin; Yan, Zhijun; Shen, Baoping

    2007-07-01

    We have fabricated three-dimensional ZnO photonic crystals by the self-assembly of SiO2/ZnO core-shell microspheres of diameter 180-220 nm by means of a vertical deposition method. The organized crystals adopt a uniform close-packed hexagonal structure with long-range order and a high filling fraction. They exhibit strong partial photonic band gaps at 565-688 nm in the transmission spectrum and a broadened band edge emission at 383 nm in the photoluminescence spectrum. For comparison with these ZnO photonic crystals, we have also prepared pure silica crystals of the same dimensions. The photonic band gaps of the former have been found to be shifted to a longer wavelength by about 200 nm compared to those of the latter as a result of the higher refractive index of ZnO. This approach provides an efficient, economical alternative means of obtaining other, more complicated photonic crystals.

  2. Solvent-Free Synthesis of Zeolite Crystals Encapsulating Gold-Palladium Nanoparticles for the Selective Oxidation of Bioethanol.

    Science.gov (United States)

    Zhang, Jian; Wang, Liang; Zhu, Longfeng; Wu, Qinming; Chen, Chunyu; Wang, Xiong; Ji, Yanyan; Meng, Xiangju; Xiao, Feng-Shou

    2015-09-07

    The conversion of bioethanol into valuable products is an important area in the conversion of biomass. We demonstrate the successful synthesis of bimetallic gold-palladium (Au-Pd) nanoparticles encapsulated within S-1 zeolite crystals (AuPd@S-1) by a solvent-free strategy. This strategy allows highly efficient use of the noble metals, with more than 96 % of the gold and palladium being loaded into the final samples. Electron microscopy characterization and investigations with probe molecules confirm that the Au-Pd nanoparticles are encapsulated inside the S-1 crystals. The AuPd@S-1 catalyst is very active for the aerobic oxidation of bioethanol, giving 100 % conversion and 99 % selectivity to acetic acid. Even in the presence of 90 % water, the catalyst still gives a conversion higher than 80 % and a selectivity of 95 %. More importantly, the AuPd@S-1 catalyst exhibits excellent stability in the oxidation of bioethanol. These features are important for future practical applications of the AuPd@S-1 catalyst.

  3. Noise-like pulse based on dissipative four-wave-mixing with photonic crystal fiber filled by reduced graphene oxide

    CERN Document Server

    Gao, Lei; Huang, Wei

    2014-01-01

    A noise-like pulse based on dissipative four-wave-mixing in a fiber cavity with photonic crystal fiber filled by reduced graphene oxide is proposed. Due to large evanescent field provided by 3 cm photonic crystal fiber and ultrahigh nonlinearity of reduced graphene oxide, this mixed structure provides excellent saturable absorption and high nonlinearity, which are necessary for generating four-wave-mixing (FWM). We experimentally prove that the mode-locked laser transfers its energy from center wavelength to sidebands through degenerate FWM, and new frequencies are generated via cascaded FWM among those sidebands. During this process, the frequencies located in various orders of longitudinal modes of the ring cavity are supported, and others are suppressed due to destructive interference. As the longitudinal modes of the cavity with a spacing of 6.874 MHz are partially supported, the loosely fixed phase relationship results in noise-like pulse with a coherent peak of 530 fs locating on a pedestal of 730.693 p...

  4. Praseodymium Cuprate Thin Film Cathodes for Intermediate Temperature Solid Oxide Fuel Cells: Roles of Doping, Orientation, and Crystal Structure.

    Science.gov (United States)

    Mukherjee, Kunal; Hayamizu, Yoshiaki; Kim, Chang Sub; Kolchina, Liudmila M; Mazo, Galina N; Istomin, Sergey Ya; Bishop, Sean R; Tuller, Harry L

    2016-12-21

    Highly textured thin films of undoped, Ce-doped, and Sr-doped Pr2CuO4 were synthesized on single crystal YSZ substrates using pulsed laser deposition to investigate their area-specific resistance (ASR) as cathodes in solid-oxide fuel cells (SOFCs). The effects of T' and T* crystal structures, donor and acceptor doping, and a-axis and c-axis orientation on ASR were systematically studied using electrochemical impedance spectroscopy on half cells. The addition of both Ce and Sr dopants resulted in improvements in ASR in c-axis oriented films, as did the T* crystal structure with the a-axis orientation. Pr1.6Sr0.4CuO4 is identified as a potential cathode material with nearly an order of magnitude faster oxygen reduction reaction kinetics at 600 °C compared to thin films of the commonly studied cathode material La0.6Sr0.4Co0.8Fe0.2O3-δ. Orientation control of the cuprate films on YSZ was achieved using seed layers, and the anisotropy in the ASR was found to be less than an order of magnitude. The rare-earth doped cuprate was found to be a versatile system for study of relationships between bulk properties and the oxygen reduction reaction, critical for improving SOFC performance.

  5. RATES OF HYDROUS FERRIC OXIDE CRYSTALLIZATION AND THE INFLUENCE ON COPRECIPITATED ARSENATE

    Science.gov (United States)

    Arsenate coprecipitated with hydrous ferric oxide (HFO) was stabilized against dissolution during transformation of HFO to more crystalline iron (hydr)oxides. The rate of arsenate stabilization approximately coincided with the rate of HFO transformation at pH 6 and 40 ?C. Compa...

  6. The photorefractive characteristics of bismuth-oxide doped lithium niobate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Dahuai; Yao, Jiaying [School of Physics, Nankai University, Tianjin 300071 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Kong, Yongfa, E-mail: kongyf@nankai.edu.cn [School of Physics, Nankai University, Tianjin 300071 (China); MOE Key Laboratory of Weak-Light Nonlinear Photonics and TEDA Applied Physics School, Nankai University, Tianjin 300457 (China); R and D Center, Taishan Sports Industry Group, Leling 253600 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Liu, Shiguo [School of Physics, Nankai University, Tianjin 300071 (China); Zhang, Ling; Chen, Shaolin [MOE Key Laboratory of Weak-Light Nonlinear Photonics and TEDA Applied Physics School, Nankai University, Tianjin 300457 (China); Xu, Jingjun [School of Physics, Nankai University, Tianjin 300071 (China); MOE Key Laboratory of Weak-Light Nonlinear Photonics and TEDA Applied Physics School, Nankai University, Tianjin 300457 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China)

    2015-01-15

    Bismuth-doped lithium niobate (LN:Bi) crystals were grown by Czochralski method and their optical damage resistance, photorefraction, absorption spectra, and defect energy levels were investigated. The experimental results indicate that the photorefractive properties of LN:Bi were enhanced as compared with congruent one, the photorefractive response time was greatly shortened, the photorefractive sensitivity was increased, and the diffraction efficiency of near-stoichiometric LN:Bi (SLN:Bi) reached 31.72% and 49.08% at 532 nm and 488 nm laser, respectively (light intensity of 400 mW/cm{sup 2}). An absorption peak at about 350 nm was observed in the absorption spectrum of LN:Bi. And the defect energy levels simulation indicates new defect levels appear in the forbidden gap of LN:Bi crystals. Therefore bismuth can act as photorefractive centers in LN crystals.

  7. The photorefractive characteristics of bismuth-oxide doped lithium niobate crystals

    Directory of Open Access Journals (Sweden)

    Dahuai Zheng

    2015-01-01

    Full Text Available Bismuth-doped lithium niobate (LN:Bi crystals were grown by Czochralski method and their optical damage resistance, photorefraction, absorption spectra, and defect energy levels were investigated. The experimental results indicate that the photorefractive properties of LN:Bi were enhanced as compared with congruent one, the photorefractive response time was greatly shortened, the photorefractive sensitivity was increased, and the diffraction efficiency of near-stoichiometric LN:Bi (SLN:Bi reached 31.72% and 49.08% at 532 nm and 488 nm laser, respectively (light intensity of 400 mW/cm2. An absorption peak at about 350 nm was observed in the absorption spectrum of LN:Bi. And the defect energy levels simulation indicates new defect levels appear in the forbidden gap of LN:Bi crystals. Therefore bismuth can act as photorefractive centers in LN crystals.

  8. Single crystal growth and magnetic excitations of transistion metal oxide CoV2 O6

    Science.gov (United States)

    Stockdale, Christopher; Wallington, F.; Taylor, J. W.; Garcia-Sakai, V.; Arevalo-Lopez, A. M.; Attfield, P.; Stock, C.

    2015-03-01

    Low-dimensional magnetic materials are an area of interest due to their unusual properties such as metamagnetism and magnetization plateaus. Solid state synthesis has produced polycrystalline CoV2O6 which exists in two polymorphs: one with a monoclinic structure, and the other with a triclinic structure. Single crystals have been grown from polycrystalline CoV2O6 using the flux method under vacuum and are large enough to aid in single crystal neutron diffraction. Magnetic excitations have been measured using powder neutron diffraction in the low temperatures regime with variable energy. The magnetic excitations have been compared between the two phases. The energy of the system has been modelled in terms of the spin-orbit coupling, structural distortions, and the crystal field and compared to neutron data.

  9. Up-Conversion Emission of Er3+ Ions in Yb3+ Sensitized Oxide Crystals

    Institute of Scientific and Technical Information of China (English)

    Wang Jun; Ruan Yongfeng; Lin Junyi; Liu Jian; Huang Boxian

    2004-01-01

    Most of the up-conversion lasers operated at room temperature are realized with heavy metal fluorides, In this paper the Judd-Ofelt parameters Ωλ ( λ = 2,4,6 ) were calculated for Er3+ ions in Yb3 + sensitized LiNbO3 and YVO4 crystals at room temperature, together with the radiative transition probabilities, non-radiative transition probabilities and resonant transition probabilities of Er3+ ions. Taking into account the energy transfer from Yb3 + to Er3 +, the rate equations are given for Er3 + ions. We obtained from a solution of the rate equations that Yb3 + sensitized YVO4 crystal is more efficient than Yb3 + sensitized LiNbO3 crystal in the up-conversion of 550 nm of Er3+ emission, which is consistent with our observation.

  10. Crystallization kinetics and optical properties of titanium-lithium tetraborate glass containing europium oxide

    Science.gov (United States)

    Mohamed, E. A.; Ratep, A.; Abdel-Khalek, E. K.; Kashif, I.

    2017-07-01

    The crystallization kinetics and optical properties of [60 Li2B4O7-30 TiO2-10 Eu2O3] (mol%) glass sample have been investigated. The present glass sample exhibits three crystallization exothermic peaks ( T p1, T p2, and T p3) corresponding to the formation of LiBO2, Li2B4O7, and EuTiO3 phases, respectively. The presence of phase separation in the glass sample has been confirmed by scanning electron microscopic (SEM). The mean values of Avrami exponent ( n = 3.1 and 4) around T p1 and T p2, indicate that the bulk crystallization with a constant number of nuclei and with an increasing number of nuclei, respectively. The values of the local activation energy as a function of the fraction of crystallization (0.1 ≤ χ ≤ 0.9) decrease for the crystallization of LiBO2 and EuTiO3 and increase for the crystallization of Li2B4O7. The values of n( χ) for T p3 and T p2 in the range (0.1 ≤ χ ≤ 0.9) and (0.1 ≤ χ ≤ 0.4), respectively, are larger than 4 indicate that the presence of anomalous in Avrami exponent. The trend of Judd-Ofelt intensity parameters (Ω2 > Ω4 > Ω6) and the bonding parameter ( δ) indicate that the lower symmetry and the highest covalent nature of the bonding around Eu3+ ions.

  11. Self-Assembly of Single-Crystal Silver Microflakes on Reduced Graphene Oxide and their Use in Ultrasensitive Sensors

    KAUST Repository

    Chen, Ye

    2016-01-19

    Compared to 1D structures, 2D structures have higher specific and active surface, which drastically improves electron transfer and extensibility along 2D plane. Herein, 2D-single crystal silver microflakes (AgMFs) are prepared for the first time in situ on reduced graphene oxide (RGO) by solvothermal synthesis with thickness around 100 nm and length around 10 μm. The oriented attachment mechanism is hypothesized to control the silver crystal growth and self-assembly of reduced silver units to form single-crystal AgMF structure on RGO sheets. Employing it as an electrode to fabricate reliable and extremely sensitive pressure sensors verifies the applicability of this novel 2D structure. Contrary to nanowires, 2D microflakes can intercalate better within the polymer matrix to provide an enhanced network for electron movement. The designed sensor can retain more than 4.7 MPa-1 after 10 000 cycles. The design proves functional for monitoring various actions such as wrist movement, squatting, walking, and delicate finger touch with high durability. A highly sensitive and flexible pressure sensor is fabricated based on the self-assembly of silver microflakes on reduced graphene oxide. This sensor exhibits an excellent pressure sensitivity as it can retain more than 4.7 MPa-1 after 10 000 cycles. This system is successfully used to monitor wrist movement, walking, and squatting and can be applied in touch screen panels, robotic systems, and prosthetics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Optical characterization of colloidal crystals based on dissymmetric metal-coated oxide submicrospheres

    Energy Technology Data Exchange (ETDEWEB)

    Portal, S. [FEMAN Group, IN2UB, University of Barcelona, Marti i Franques, 1, E-08028 Barcelona (Spain)], E-mail: sabineportal@hotmail.com; Vallve, M.A. [SOC and SAM Group, IN2UB, University of Barcelona, Marti i Franques, 1, E-08028 Barcelona (Spain); Arteaga, O. [FEMAN Group, IN2UB, University of Barcelona, Marti i Franques, 1, E-08028 Barcelona (Spain); Ignes-Mullol, J. [SOC and SAM Group, IN2UB, University of Barcelona, Marti i Franques, 1, E-08028 Barcelona (Spain); Canillas, A.; Bertran, E. [FEMAN Group, IN2UB, University of Barcelona, Marti i Franques, 1, E-08028 Barcelona (Spain)

    2008-12-01

    We studied the optical properties of a two-dimensional (2D) photonic crystal monolayer made up of silica submicrospheres, partly covered by a metallic coating. The silica particles, synthesized by the Stoeber method, had a diameter of about 300 nm, with little size dispersion. They were deposited on glass in a hexagonal pattern by the Langmuir-Blodgett process. The resulting film consisted of a single monolayer of particles. The final step of sample preparation consisted of depositing a discontinuous gold layer on top of the 2D crystal. In order to evaluate the effects of small compositional and structural changes on the optical properties of the 2D crystal, the gold layer was applied to a thickness of less than 2 nm. Anisotropy in the metallic coating was induced by tilting the deposition angle by 10 deg. from the vertical: a discontinuous layer was obtained on top of the particles, with elongated shapes pointing towards the source of the evaporation. The shape of the particles and the film structure were characterized by scanning electron microscopy. Ellipsometric measurements were performed in transmission mode in order to assess the sample anisotropy, and the plasmon response of the samples was determined by extinction measurements. The original 2D crystal presented unexpected optical and uniaxial anisotropy which was increased by a factor of 2 after gold coating.

  13. Ion effects in the adsorption of carboxylate on oxide surfaces, studied with quartz crystal microbalance

    NARCIS (Netherlands)

    Wang, Lei; Siretanu, Igor; Duits, Michel H.G.; Cohen Stuart, Martien A.; Mugele, Frieder

    2016-01-01

    We chose water-soluble sodium hexanoate as a model organic molecule to study the role of salt ions (Ca2+, Na+, Cl−) in the adsorption of carboxylates to mineral surfaces (silica, alumina, gibbsite) of variable surface charge and chemistry. Quartz crystal microbalance (QCM-D) measurements reveal a qu

  14. Synthesis, crystal growth and characterization of g-phase bismuth titanium oxide with gallium

    Directory of Open Access Journals (Sweden)

    Lobato A.R.

    2000-01-01

    Full Text Available Gallium solubility in the Bi12TiO20 (BTO matrix was investigated by solid state reaction synthesis and Bi12Ti(1-xGa xO20 (BTGaO single crystals were grown by Top Seeded Solution Growth (TSSG. We determined that it is possible to obtain a continuous solid solution from (xBi12TiO20: (1-xBi12[Ga0.7Bi0.3]O20 and that Ga replaces Ti in the BTO matrix giving Bi12Ti(1-xGa(xO20 up to x < 0.2. BTGaO single crystals grown with an excess of Bi2O3 were transparent, a bleaching effect was observed due to the presence of gallium in the crystalline sillenite structure and their lattice parameter was higher than for pure BTO. The results for BTGaO single crystals showed an increase in the optical activity from rho0 = 6.4° ± 0.3°/mm, for BTO, to rho0 = 9.7° ± 0.3°/mm, for BTGaO grown with x = 0.30 in the melt. The BTGaO crystal presented an activation energy value of 0.48 ± 0.02 eV for 100 °C <= T <= 300 °C.

  15. Final Report: The Impact of Carbonate on Surface Protonation, Electron Transfer and Crystallization Reactions in Iron Oxide Nanoparticles and Colloids

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, David Adams [The University of Alabama

    2013-07-02

    This project addresses key issues of importance in the geochemical behavior of iron oxides and in the geochemical cycling of carbon and iron. For Fe, we are specifically studying the influence of carbonate on electron transfer reactions, solid phase transformations, and the binding of carbonate to reactive sites on the edges of particles. The emphasis on carbonate arises because it is widely present in the natural environment, is known to bind strongly to oxide surfaces, is reactive on the time scales of interest, and has a speciation driven by acid-base reactions. The geochemical behavior of carbonate strongly influences global climate change and CO{sub 2} sequestration technologies. Our goal is to answer key questions with regards to specific site binding, electron transfer reactions, and crystallization reactions of iron oxides that impact both the geochemical cycling of iron and CO{sub 2} species. Our work is focused on the molecular level description of carbonate chemistry in solution including the prediction of isotope fractionation factors. We have also done work on critical atmospheric species.

  16. Self-catalytic crystal growth, formation mechanism, and optical properties of indium tin oxide nanostructures.

    Science.gov (United States)

    Liang, Yuan-Chang; Zhong, Hua

    2013-08-22

    In-Sn-O nanostructures with rectangular cross-sectional rod-like, sword-like, and bowling pin-like morphologies were successfully synthesized through self-catalytic growth. Mixed metallic In and Sn powders were used as source materials, and no catalyst layer was pre-coated on the substrates. The distance between the substrate and the source materials affected the size of the Sn-rich alloy particles during crystal growth in a quartz tube. This caused In-Sn-O nanostructures with various morphologies to form. An X-ray photoelectron spectroscope and a transmittance electron microscope with an energy-dispersive X-ray spectrometer were used to investigate the elemental binding states and compositions of the as-synthesized nanostructures. The Sn doping and oxygen vacancies in the In2O3 crystals corresponded to the blue-green and yellow-orange emission bands of the nanostructures, respectively.

  17. Synthesis of single crystal manganese oxide octahedral molecular sieve (OMS) nanostructures with tunable tunnels and shapes.

    Science.gov (United States)

    Li, Wei-Na; Yuan, Jikang; Gomez-Mower, Sinue; Sithambaram, Shantakumar; Suib, Steven L

    2006-02-23

    A new and facile route is reported to manipulate the self-assembly synthesis of hierarchically ordered Rb-OMS-2 and pyrolusite with an interesting flowerlike morphology by a direct and mild reaction between rubidium chromateand manganese sulfate without any organic templates. The crystal forms, morphologies, and tunnel sizes of the obtained OMS materials can be controlled. A mechanism for the growth of manganese dioxides with flowerlike architectures was proposed. The obtained products exhibit potential for use in catalysis and other applications.

  18. Generation of Tin(II) Oxide Crystals on Lead-Free Solder Joints in Deionized Water

    Science.gov (United States)

    Chang, Hong; Chen, Hongtao; Li, Mingyu; Wang, Ling; Fu, Yonggao

    2009-10-01

    The effect of the anode and cathode on the electrochemical corrosion behavior of lead-free Sn-Ag-Cu and Sn-Ag-Cu-Bi solder joints in deionized water was investigated. Corrosion studies indicate that SnO crystals were generated on the surfaces of all lead-free solder joints. The constituents of the lead-free solder alloys, such as Ag, Cu, and Bi, did not affect the corrosion reaction significantly. In contrast to lead-free solders, PbO x was formed on the surface of the traditional 63Sn-37Pb solder joint in deionized water. A cathode, such as Au or Cu, was necessary for the electrochemical corrosion reaction of solders to occur. The corrosion reaction rate decreased with reduction of the cathode area. The formation mechanism of SnO crystals was essentially a galvanic cell reaction. The anodic reaction of Sn in the lead-free solder joints occurred through solvation by water molecules to form hydrated cations. In the cathodic reaction, oxygen dissolved in the deionized water captures electrons and is deoxidized to hydroxyl at the Au or Cu cathode. By diffusion, the anodic reaction product Sn2+ and the cathodic reaction product OH- meet to form Sn(OH)2, some of which can dehydrate to form more stable SnO· xH2O crystals on the surface of the solder joints. In addition, thermodynamic analysis confirms that the Sn corrosion reaction could occur spontaneously.

  19. Carboxylic and dicarboxylic acids extracted from crushed magnesium oxide single crystals

    Science.gov (United States)

    Freund, F.; Gupta, A. D.; Kumar, D.

    1999-01-01

    Carboxylic and dicarboxylic acids (glycolic, oxalic, malonic and succinic) have been extracted with tetrahydrofuran (THF) and H2O from large synthetic MgO crystals, crushed to a medium fine powder. The extracts were characterized by infrared spectroscopy and 1H-NMR. The THF extracts were derivatized with tert-butyldimethylsilyl (t-BDMS) for GC-MS analysis. A single crystal separated from the extract was used for an x-ray structure analysis, giving the monoclinic unit cell, space group P21/c with ao = 5.543 A, bo = 8.845 A, co = 5.086 A, and beta = 91.9 degrees, consistent with beta-succinic acid, HOOC(CH2)COOH. The amount of extracted acids is estimated to be of the order of 0.1 to 0.5 mg g-1 MgO. The MgO crystals from which these organic acids were extracted grew from the 2860 degrees C hot melt, saturated with CO/CO2 and H2O, thereby incorporating small amounts of the gaseous components to form a solid solution (ss) with MgO. Upon cooling, the ss becomes supersaturated, causing solute carbon and other solute species to segregate not only to the surface but also internally, to dislocations and subgrain boundaries. The organic acids extracted from the MgO crystals after crushing appear to derive from these segregated solutes that formed C-C, C-H and C-O bonds along dislocations and other defects in the MgO structure, leading to entities that can generically be described as (HxCyOz)n-. The processes underlying the formation of these precursors are fundamental in nature and expected to be operational in any minerals, preferentially those with dense structures, that crystallized in H2O-CO2-laden environments. This opens the possibility that common magmatic and metamorphic rocks when weathering at the surface of a tectonically active planet like Earth may be an important source of abiogenically formed complex organic compounds.

  20. Hydrothermal synthesis and crystal structure of a new lithium copper bismuth oxide, LiCuBiO4

    Science.gov (United States)

    Kumada, Nobuhiro; Nakamura, Ayumi; Miura, Akira; Takei, Takahiro; Azuma, Masaki; Yamamoto, Hajime; Magome, Eisuke; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2017-01-01

    A new lithium copper bismuth oxide, LiCuBiO4 was prepared by hydrothermal reaction using NaBiO30.1*4H2O. The crystal structural model of this compound was refined by using synchrotron X-ray powder diffraction data. This bismuthate has the LiCuSbO4 related structure with the orthorhombic cell (Space group: Pnma) of a=10.9096(9), b=5.8113(5) and c=5.0073(4) Å, and the final R-factors were Rwp=4.84 and Rp=3.58%. This compound is the first example of a lithium copper bismuthate containing Bi5+. An antiferromagnetic ordering of Cu2+ moment was observed at 6 K.

  1. Crystal structure of peroxide stress regulator from Streptococcus pyogenes provides functional insights into the mechanism of oxidative stress sensing.

    Science.gov (United States)

    Makthal, Nishanth; Rastegari, Sheila; Sanson, Misu; Ma, Zhen; Olsen, Randall J; Helmann, John D; Musser, James M; Kumaraswami, Muthiah

    2013-06-21

    Regulation of oxidative stress responses by the peroxide stress regulator (PerR) is critical for the in vivo fitness and virulence of group A Streptococcus. To elucidate the molecular mechanism of DNA binding, peroxide sensing, and gene regulation by PerR, we performed biochemical and structural characterization of PerR. Sequence-specific DNA binding by PerR does not require regulatory metal occupancy. However, metal binding promotes higher affinity PerR-DNA interactions. PerR metallated with iron directly senses peroxide stress and dissociates from operator sequences. The crystal structure revealed that PerR exists as a homodimer with two metal-binding sites per subunit as follows: a structural zinc site and a regulatory metal site that is occupied in the crystals by nickel. The regulatory metal-binding site in PerR involves a previously unobserved HXH motif located in its unique N-terminal extension. Mutational analysis of the regulatory site showed that the PerR metal ligands are involved in regulatory metal binding, and integrity of this site is critical for group A Streptococcus virulence. Interestingly, the metal-binding HXH motif is not present in the structurally characterized members of ferric uptake regulator (Fur) family but is fully conserved among PerR from the genus Streptococcus. Thus, it is likely that the PerR orthologs from streptococci share a common mechanism of metal binding, peroxide sensing, and gene regulation that is different from that of well characterized PerR from Bacillus subtilis. Together, our findings provide key insights into the peroxide sensing and regulation of the oxidative stress-adaptive responses by the streptococcal subfamily of PerR.

  2. Real-time observation of bismuth silicon oxide crystal growth in silicon oxide-bismuth oxide system%氧化硅-氧化铋系统中硅酸铋晶体生长实时观测

    Institute of Scientific and Technical Information of China (English)

    王秀峰; 徐驰; 江红涛; 韩元亨

    2015-01-01

    高温熔体的实时观测与分析对于晶体生长及其影响因素分析具有十分重要的意义 .利用高温热台及偏光显微镜 ,对铋硅系统熔融及冷却过程进行实时观测 .观察到高温下与石英砂接触的氧化铋粉体先熔融 ,说明异质颗粒接触点处是反应开始的地方 .之后熔体与石英(二氧化硅)晶体反应 ,冷却过程中在石英晶体表面周围及坩埚壁附近生长出硅酸铋晶体 ,这说明晶体易在颗粒接触处析出 .实验中氧化铋与二氧化硅摩尔比为4:3,此时石英晶体并没有全部熔融 .对比分析系统熔体在降温时晶体析出长大的过程 ,计算出硅酸铋晶体的生长平均速率为15 .38 μm/min .通过线能谱扫描分析 ,认为熔体温度和硅元素的富集程度对晶体生长速度有重要影响.%Real time observation and analysis of high temperature melt is great of significance for crystal growth and the analysis of its influencing factors .The paper using high tempera-ture thermal units and polarizing optical microscope observed the melt and cooling process of bismuth silicon systems in real time .In high temperature the bismuth oxide powder which in contact with quartz sand is first melting ,it shows that the heterogeneity particles at the con-tact point is the place to reaction start .Then bismuth oxide melt reacted with the quartz (sil-icon dioxide) crystal .In cooling process the surface of quartz crystal and the crucible wall grown bismuth silicate crystals .This means at the contact point of particle is easy to crystal grow .The molar ratio of bismuth oxide and silicon dioxide was 4:3 in the experiment ,not all of the quartz crystal melted at this moment .Comparative analysis of the system melt crystallization process of growing up in cooling process ,the average grow th rate of crystals of bismuth silicate is calculated 15 .38 μm/min .According to the energy spectrum analysis of scanning ,melt temperature and the enrichment of

  3. Electro-optic switching in iron oxide nanoparticle embedded paramagnetic chiral liquid crystal via magneto-electric coupling

    Energy Technology Data Exchange (ETDEWEB)

    Goel, Puja, E-mail: pujagoel@gmail.com [Division of Agricultural Chemicals, Indian Agricultural Research Institute, New Delhi 110012 (India); Arora, Manju; Biradar, Ashok M. [Materials Physics and Engineering Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012 (India)

    2014-03-28

    The variation in optical texture, electro-optic, and dielectric properties of iron oxide nanoparticles (NPs) embedded ferroelectric liquid crystal (FLC) with respect to change in temperature and electrical bias conditions are demonstrated in the current investigations. Improvement in spontaneous polarization and response time in nanocomposites has been attributed to magneto-electric (ME) coupling resulting from the strong interaction among the ferromagnetic nanoparticle's exchange field (due to unpaired e{sup −}) and the field of liquid crystal molecular director. Electron paramagnetic resonance spectrum of FLC material gives a broad resonance signal with superimposed components indicating the presence of a source of spin. This paramagnetic behavior of host FLC material had been a major factor in strengthening the guest host interaction by giving an additional possibility of (a) spin-spin interaction and (b) interactions between magnetic-dipole and electric-dipole moments (ME effects) in the composite materials. Furthermore, the phenomenon of dielectric and static memory effect in these composites are also observed which yet again confirms the coupling of magnetic NP's field with FLC's director orientation. We therefore believe that such advanced soft materials holding the optical and electrical properties of conventional LCs with the magnetic and electronic properties of ferromagnetic nanoparticles are going to play a key role in the development of futuristic multifunctional optical devices.

  4. Synthesis and Crystal Structure of Tri-(2-mercaptopyridine N-oxide)bis(dimethyl sulfoxide) Dysprosium(Ⅲ)

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A range of rare earth metal complexes of 2-mercaptopyridine N-oxide (Hmpo) have been synthesized, and studied by elemental analysis and IR spectroscopic technique. Crystal structure of Dy(mpo)3(DMSO)2 (DMSO = dimethyl sulfoxide) has been determined. The complex crystallizes in the triclinic system, space group Pī with lattice parameters: a = 9.602(3), b = 9.803(3), c = 15.498(5)A, α= 89.51(1), β= 85.73(1), γ= 62.99(1)°, Dc = 1.787 g/cm3, C19H24N3O5S5Dy, Mr = 697.21, Z = 2, F(000) = 690, μ = 3.321mm-1, the final R = 0.0237 and wR = 0.0587 for 4116 reflections with I>σ2(I). The coordination number of dysprosium Ⅲ is eight, and its coordination geometry is a somewhat distorted square antiprism with O(3), O(4), O(5), S(3) and O(1), O(2), S(1), S(2) at the tetragonal bases (dihedral angle between their mean planes is 2.9(1)0). Around the Dy atom, three five-membered ring planes (Dy, O, N, C, S) make the dihedral angles of 74.42, 11.31 and 83.72, respectively.

  5. Synthesis and Crystal Structure of 3-Nitrophthalic Acid·3-methyl-4-nitropyridine N-Oxide Adducts

    Institute of Scientific and Technical Information of China (English)

    WANG Yi; FENG Wei; XUE Lin; ZHENG Ji-Min

    2006-01-01

    The title compound, a 1:1 molecular adduct of 3-nitrophthalic acid and 3-methyl-4-nitropyridine N-oxide (PPOM), has been synthesized and characterized by X-ray single-crystal structure analysis. It crystallizes in triclinic, space group P-1 with a = 7.6076(15), b = 7.8180(16), c= 14.546(3) (A), α= 93.90(3), β = 97.21(3), γ= 114.43(3)°, C14H11N3O9, Mr = 365.26,Z=2,V=774.6(3) (A)3, Dc = 1.566 g/m3, u(MoKα) = 0.134 mm-1, F(000) = 376, R = 0.0538 and Wr = 0.1460 for 885 observed reflections (I>2σ(I)). The protons of the carbonylic acids in the molecule are not transferred and the O-H…O and C-H…O hydrogen bonds form zigzag chains in the molecule.

  6. Nanoparticle films and photonic crystal multilayers from colloidally stable, size-controllable zinc and iron oxide nanoparticles.

    Science.gov (United States)

    Redel, Engelbert; Mirtchev, Peter; Huai, Chen; Petrov, Srebri; Ozin, Geoffrey A

    2011-04-26

    We report a facile sol-gel synthesis of colloidally stable Fe(2)O(3) and ZnO nanoparticles in alcoholic solvents, ROH, where R = methyl, ethyl, n-propyl, isopropyl, and tert-butyl. We show that nanoparticles of ZnO (4-42) nm and Fe(2)O(3) (4-38 nm) monotonically increase in size upon increasing the alkyl chain length and branching of the alcohol solvent. These colloidally stable and size-controllable metal oxide nanoparticles enable the formation of high optical quality films and photonic crystal multilayers whose component layer thickness, refractive index, porosity, and surface area are found to scale with the nature of the alcohol. Utility of these colloidally stable nanoparticles is demonstrated by preparation of one-dimensional porous photonic crystals comprising ncZnO/ncWO(3) and ncFe(2)O(3)/ncWO(3) multilayers whose photonic stop band can be tuned by tailoring nanoparticle size. Myriad applications can be envisaged for these nanoparticle films in, for example, heterogeneous catalysis, photocatalysis, electrocatalysis, chemical sensors, and solar cells.

  7. Size of the fragment for crystal cluster SCF-X/sub /-SW calculations of alkaline earth metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Lobach, V.A.; Sobolev, A.B.; Shul' gin, B.V.

    Calculation of (A/sub x/B/sub y/) (x=1, 13; y=6, 14) clusters, corresponding to ideal crystals of alkaline earth metal oxides (AEMO) MgO, CaO, SrO by means of molecular cluster (MC) and crystal cluster (CC) SCF-X/sub /-SW method is carried out. MC method is not suitable for description of ideal AEMO electron structure due to long-range Coulomb interaction and potential cluster effect. Even in CC method at x < 13 and y < 14 (A/sub x/B/sub y/) cluster nonstoichiometry is inhibitory to the obtaining of satisfactory agreement with the experimental optical and X-ray spectra. (A13B14) and (B13A14) clusters satisfactorily reproduce partial composition of valence band (VB) and conduction band (CB), VB and CB widths, a fine structure of oxygen K-emission spectra in MgO and also experimental distribution of electron density. Sphere radii variation effect on the value of intersphere region error with muffin-tin averaging is considered.

  8. Emission cross sections and energy extraction for the mid-infrared transitions of Er, Tm, and Ho in oxide and fluoride crystals

    Science.gov (United States)

    Chase, L. L.; Payne, S. A.; Smith, L. K.; Kway, W. L.; Krupke, W. F.

    Emission cross sections have been measured for the transitions between the two lowest spin orbit multiplets of Er, Tm, and Ho in several fluoride and oxide crystals. Properties affecting energy extraction efficiency are summarized and pulsed extraction performance is calculated for several of these quasi-three-level laser media.

  9. Modes of Heme-Binding and Substrate Access for Cytochrome P450 CYP74A Revealed by Crystal Structures of Allene Oxide Synthase

    Science.gov (United States)

    Cytochrome P450s exist ubiquitously in all organisms and are involved in many biological processes. Allene oxide synthase (AOS) is a P450 enzyme that plays a key role in the biosynthesis of oxylipin jasmonates which are involved in signal and defense reactions in higher plants. The crystal structure...

  10. Investigation of the Effect of Yttrium Oxide Nanoparticles Doped with Cerium and Neodymium on Electro-Optics of Liquid Crystal Polymer Composites

    Science.gov (United States)

    Zharkova, G. M.; Osipov, V. V.; Platonov, V. V.; Podkin, A. V.; Strel'tsov, S. A.

    2016-12-01

    Morphology and properties of liquid crystal polymer composites doped with inorganic nanoparticles are described. These composites comprised nematic liquid crystal 5CB, polyvinyl acetate, and nanoparticles of oxides (Y2O3, CeO2:Y2O3, and Nd2O3:Y2O3). Nanopowders were synthesized by the laser method of vaporization of a solid target under CO2-laser or fiber ytterbium laser irradiation. The effect of oxides on the electro-optical properties of the composites and times of response to an electrical pulse is investigated. It is shown that incorporation of CeO2:Y2O3 nanopowder in liquid crystal polymer composites affects the decrease of the control field and the increase of light transmission in an electric field stronger than incorporation of Nd2O3:Y2O3 nanoparticles.

  11. Improvement of the Oxidation Resistance of the Single-Crystal Ni-Based TMS-82+ Superalloy by Ni–Al Coatings with/without the Diffusion Barrier

    OpenAIRE

    Wu, Y.; Li, X. W.; Song, G.M.; Wang, Y. M.; Narita, T.

    2010-01-01

    Oxidation behavior of the uncoated base, Ni–Al coated and Re–Cr-Ni plus Ni–Al coated single-crystal (SC) Ni-based TMS-82+ superalloy is studied under cyclic air at 900ºC for 200 h to assess the oxidation resistance. Regardless of the coating processing, Ni–Al coating is effective in improving the oxidation resistance due to the formation of a continuous a-Al2O3 layer in the scale. For the uncoated base superalloy, the mass-gain curves are fitted by a subparabolic relationship, and complex oxi...

  12. Crystal structure of quinone-dependent alcohol dehydrogenase from Pseudogluconobacter saccharoketogenes. A versatile dehydrogenase oxidizing alcohols and carbohydrates.

    Science.gov (United States)

    Rozeboom, Henriëtte J; Yu, Shukun; Mikkelsen, Rene; Nikolaev, Igor; Mulder, Harm J; Dijkstra, Bauke W

    2015-12-01

    The quinone-dependent alcohol dehydrogenase (PQQ-ADH, E.C. 1.1.5.2) from the Gram-negative bacterium Pseudogluconobacter saccharoketogenes IFO 14464 oxidizes primary alcohols (e.g. ethanol, butanol), secondary alcohols (monosaccharides), as well as aldehydes, polysaccharides, and cyclodextrins. The recombinant protein, expressed in Pichia pastoris, was crystallized, and three-dimensional (3D) structures of the native form, with PQQ and a Ca(2+) ion, and of the enzyme in complex with a Zn(2+) ion and a bound substrate mimic were determined at 1.72 Å and 1.84 Å resolution, respectively. PQQ-ADH displays an eight-bladed β-propeller fold, characteristic of Type I quinone-dependent methanol dehydrogenases. However, three of the four ligands of the Ca(2+) ion differ from those of related dehydrogenases and they come from different parts of the polypeptide chain. These differences result in a more open, easily accessible active site, which explains why PQQ-ADH can oxidize a broad range of substrates. The bound substrate mimic suggests Asp333 as the catalytic base. Remarkably, no vicinal disulfide bridge is present near the PQQ, which in other PQQ-dependent alcohol dehydrogenases has been proposed to be necessary for electron transfer. Instead an associated cytochrome c can approach the PQQ for direct electron transfer. © 2015 The Protein Society.

  13. Superconductivity of oxide film electrolytically deposited on surface of B(1-x)Sb(x) single crystal

    Science.gov (United States)

    Alfeyev, V. N.; Aminov, B. A.; Brandt, N. B.; Vasina, S. Ya.; Damaskin, B. B.; Zigel, M.; Kuznetsov, V. P.; Petriy, O. A.; Ponomarev, Ya. G.; Sudakova, M. V.

    1990-10-01

    An experimental study was made of thin oxide films electrolytically deposited on the surface of Bi(1-x)Sb(x) single crystals (x from 0.1 to 0.3) at room temperature, the electrolyte consisting of acetonitrile as solvent with salicylic acid as conductive additive and containing copper ions. The current-voltage characteristics of point junctions produced by mechanical pressure on oxidized surfaces were measured at temperatures ranging from 1.7 K to above 20 K. They were found in most cases to be characteristic of Josephson junctions, with a critical current in the milliampere range at 4.2 K, with Mersero constant-period oscillations of the differential electrical conductance dI/dV near zero voltage in a magnetic field, and with Shapiro plateaus in a microwave field. The critical temperature of superconducting transition corresponding to maximum differential electrical conductance near zero voltage was found to be within 6 to 8 K in most cases and 20 K or higher in some cases.

  14. Titanium Oxide Crystallization and Interface Defect Passivation for High Performance Insulator-Protected Schottky Junction MIS Photoanodes.

    Science.gov (United States)

    Scheuermann, Andrew G; Lawrence, John P; Meng, Andrew C; Tang, Kechao; Hendricks, Olivia L; Chidsey, Christopher E D; McIntyre, Paul C

    2016-06-15

    Atomic layer deposited (ALD) TiO2 protection layers may allow for the development of both highly efficient and stable photoanodes for solar fuel synthesis; however, the very different conductivities and photovoltages reported for TiO2-protected silicon anodes prepared using similar ALD conditions indicate that mechanisms that set these key properties are, as yet, poorly understood. In this report, we study hydrogen-containing annealing treatments and find that postcatalyst-deposition anneals at intermediate temperatures reproducibly yield decreased oxide/silicon interface trap densities and high photovoltage. A previously reported insulator thickness-dependent photovoltage loss in metal-insulator-semiconductor Schottky junction photoanodes is suppressed. This occurs simultaneously with TiO2 crystallization and an increase in its dielectric constant. At small insulator thickness, a record for a Schottky junction photoanode of 623 mV photovoltage is achieved, yielding a photocurrent turn-on at 0.92 V vs NHE or -0.303 V with respect to the thermodynamic potential for water oxidation.

  15. Why (1 0 0) terraces break and make bonds: oxidation of dimethyl ether on platinum single-crystal electrodes.

    Science.gov (United States)

    Li, Hongjiao; Calle-Vallejo, Federico; Kolb, Manuel J; Kwon, Youngkook; Li, Yongdan; Koper, Marc T M

    2013-09-25

    A surface structural preference for (1 0 0) terraces of fcc metals is displayed by many bond-breaking or bond-making reactions in electrocatalysis. Here, this phenomenon is explored in the electrochemical oxidation of dimethyl ether (DME) on platinum. The elementary C-O bond-breaking step is identified and clarified by combining information obtained from single-crystal experiments and density functional theory (DFT) calculations. Experiments on Pt(1 0 0), Pt(5 1 0), and Pt(10 1 0) surfaces show that the surface structure sensitivity is due to the bond-breaking step, which is unfavorable on step sites. DFT calculations suggest that the precursor for the bond-breaking step is a CHOC adsorbate that preferentially adsorbs on a square ensemble of four neighboring atoms on Pt(1 0 0) terraces, named as "the active site". Step sites fail to strongly adsorb CHOC and are, therefore, ineffective in breaking C-O bonds, resulting in a decrease in activity on surfaces with increasing step density. Our combined experimental and computational results allow the formulation of a new mechanism for the electro-oxidation of DME as well as a simple general formula for the activity of different surfaces toward electrocatalytic reactions that prefer (1 0 0) terrace active sites.

  16. The electro-oxidation of the mixture of formaldehyde and 2-propanol on gold (100 and (111 single crystal planes in alkaline medium

    Directory of Open Access Journals (Sweden)

    BRANISLAV Z. NIKOLIC

    2000-12-01

    Full Text Available The effect of formaldehyde on the oxidation of 2-propanol and vice versa on gold single crystal planes (100 and 111 was studied. An activating effect in the reaction of the simultaneous oxidation of 2-propanol and formaldehyde was obtained on a gold (100 plane. In the case of a gold (111 electrode, the activation effect was not obtained. It was concluded that the adsorption of formaldehyde on the electrode surface prevents the adsorption of poisoning species formed during the electro-oxidation of 2-propanol on the Au(100 plane, while this is not the case on the Au(111 plane. The different behaviour is caused by the difference in the symmetry of the surface atoms of these two Au single-crystal planes.

  17. Single-crystal star-like zinc oxide: synthesis, characterization and growth mechanism

    Institute of Scientific and Technical Information of China (English)

    WANG Qingxiao; YOU Liping; Zhang Xinzheng; WANG Rongming; LV Yuzhen; GUO Lin

    2006-01-01

    A novel star-like single-crystal ZnO structure was synthesized by a simple solvothermal method.The as-prepared products were characterized by XRD, SEM and TEM.The star-like ZnO, which shows sixfold symmetry, was constructed by six uniform arms distributing symmetrically around the [0001] zone axis.It is also found that the arms are not perpendicular to the [0001] zone axis and each arm is grown at a certain angle with the [0001] direction.CBED pattern and corresponding simulation demonstrate that the convex part of the star-like ZnO is O-terminated (000-1) plane and the concave part is Zn-terminated (0001) plane.H2S plays a crucial role in the synthesis process.The anisotropic growth habit along [0001] and [000-1] results in the formation of star-like structure.

  18. Modulation of electrical mobility in Au ion irradiated titanium oxide with crystal field splitting

    Science.gov (United States)

    Park, Hyun-Woo; Jun, Byung-Hyuk; Choi, Dukhyun; Chung, Kwun-Bum

    2016-11-01

    Electrical modulation of radio frequency (RF) sputtered TiO2- x films were investigated as a function of Au swift heavy ion irradiation dose at room temperature. The prepared TiO2- x films were irradiated with 130 MeV Au swift heavy ion in the range from 1 × 1011 to 5 × 1012 ions/cm2. As the Au ion irradiation dose increased up to 1 × 1012 ions/cm2, the electrical mobility of TiO2- x films were dramatically increased 3.07 × 102 cm2 V-1 s-1 without the change of carrier concentration. These changes in electrical properties of Au irradiated TiO2- x film, are related to the modification of electronic structure such as crystal field splitting of Ti 3d orbital hybridization and sub-band edge states below the conduction band as a function of Au swift heavy ion irradiation dose.

  19. Spontaneous Water Oxidation at Hematite (α-Fe2O3) Crystal Faces

    Energy Technology Data Exchange (ETDEWEB)

    Chatman, Shawn ME; Zarzycki, Piotr P.; Rosso, Kevin M.

    2015-01-28

    Hematite (α-Fe2O3) persists as a promising candidate for photoelectrochemical water splitting but a slow oxygen evolution reaction (OER) at its surfaces remains a limitation. Here we extend a series of studies that examine pH-dependent surface potentials and electron transfer properties of effectively perfect low-index crystal faces of hematite in contact with simple electrolyte. Zero resistance amperometry was performed in a two electrode configuration to quantify spontaneous dark current between hematite crystal face pairs (001)/(012), (001)/(113), and (012)/(113) at pH 3. Exponentially decaying currents initially of up to 200 nA were reported between faces over four minute experiments. Fourth order ZRA kinetics indicated rate limitation by the OER for current that flows between (001)/(012) and (001)/(113) face pairs, with the (012) and (113) faces serving as the anodes when paired with (001). The cathodic partner reaction is reductive dissolution of the (001) face, converting surface Fe3+ to solubilized aqueous Fe2+, at a rate maintained by the OER at the anode. In contrast, OER rate limitation does not manifest for the (012)/(113) pair. The uniqueness of the (001) face is established in terms of a faster intrinsic ability to accept the protons required for the reductive dissolution reaction. OER rate limitation inversely may thus arise from sluggish kinetics of hematite surfaces to dispense with the protons that accompany the four-electron OER. The results are explained in terms of semi-quantitative energy band diagrams. The finding may be useful as a consideration for tailoring the design of polycrystalline hematite photoanodes that present multiple terminations to the interface with electrolyte.

  20. Optical and Morphological Characterization of Sonochemically Assisted Europium Doped Copper (I) Oxide Nanostructures

    Science.gov (United States)

    Cosico, J. A. M.; Ruales, P. K.; Marquez, M. C.

    2017-06-01

    In the age where application of nanotechnology in our society has proven to be eminent, different routes of synthesizing nanoparticles have emerged. In this study nanoparticles of cuprous oxide (Cu2O) doped with different amounts of europium was prepared by using solution precursor route approach with the aid of ultrasonic sound. Copper sulphate and europium (III) nitrate pentahydrate was used as source for copper ions and europium ions respectively. X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR) were used to elucidate the cubic crystal structure and organic impurities present on Cu2Onanoparticles. UV-Vis spectroscopy was used to determine the absorption spectrum of the nanoparticles in the wavelength range of 400nm to 700nm. The bandgap of the undoped and doped Cu2O were found to fall between 2.1eV - 2.3eV. Scanning Electron Microscopy (SEM) coupled with energy dispersive x-ray was used to observe the dendritic and rodlike morphology and the presence of europium in the synthesized Cu2O nanoparticles. The observed effect on the absorbance of Cu2O upon adding Eu and a facile way of synthesizing Cu2O nanoparticles could bring a positive impact on the production of functional devices for optoelectronic and energy applications.

  1. Copper oxide as a high temperature battery cathode material

    Science.gov (United States)

    Ritchie, A. G.; Mullins, A. P.

    1994-10-01

    Copper oxide has been tested as a cathode material for high temperature primary reserve thermal batteries in single cells at 530 to 600 C and at current densities of 0.1 to 0.25 A cm(exp -2) using lithium-aluminium alloy anodes and lithium fluoride-lithium chloride-lithium bromide molten salt electrolytes. Initial on-load voltages were around 2.3 V, falling to 1.5 V after about 0.5 F mol(exp -1) had been withdrawn. Lithium copper oxide, LiCu2O2, and cuprous oxide, Cu2O, were identified as discharge products.

  2. Reduction and Immobilization of Potassium Permanganate on Iron Oxide Catalyst by Fluidized-Bed Crystallization Technology

    Directory of Open Access Journals (Sweden)

    Guang-Xia Li

    2012-03-01

    Full Text Available A manganese immobilization technology in a fluidized-bed reactor (FBR was developed by using a waste iron oxide (i.e., BT-3 as catalyst which is a by-product from the fluidized-bed Fenton reaction (FBR-Fenton. It was found that BT-3 could easily reduce potassium permanganate (KMnO4 to MnO2. Furthermore, MnO2 could accumulate on the surface of BT-3 catalyst to form a new Fe-Mn oxide. Laboratory experiments were carried out to investigate the KMnO4-reduction mechanism, including the effect of KMnO4 concentration, BT-3 dosage, and operational solution pH. The results showed that the pH solution was a significant factor in the reduction of KMnO4. At the optimum level, pHf 6, KMnO4 was virtually reduced in 10 min. A pseudo-first order reaction was employed to describe the reduction rate of KMnO4.

  3. Structural effects of electrochemical oxidation of formic acid on single crystal electrodes of palladium.

    Science.gov (United States)

    Hoshi, Nagahiro; Kida, Kaori; Nakamura, Masashi; Nakada, Miou; Osada, Kazuhito

    2006-06-29

    Structural effects on the rates of formic acid oxidation have been studied on Pd(111), Pd(100), Pd(110), and Pd(S)-[n(100) x (111)] (n = 2-9) electrodes in 0.1 M HClO4 containing 0.1 M formic acid with use of voltammetry. On the low index planes of Pd, the maximum current density of formic acid oxidation (jP) increases in the positive scan as follows: Pd(110) Pd(111) Pd(100). This order differs from that on the low index planes of Pt: Pt(111) Pd(S)-[n(100) x (111)] electrodes with terrace atomic rows n > or = 3 have almost the same jP as Pd(100), except Pd(911) n = 5. The value of jP on Pd(911) n = 5 is 20% higher than those of the other surfaces. Pd(311) n = 2, of which the first layer is composed of only step atoms, has the lowest jP in the Pd(S)-[n(100) x (111)] series. The adsorption geometry of the reaction intermediate (formate ion) is optimized by using density functional theory.

  4. Cobalt containing crystallizing glass seals for solid oxide fuel cells - A new strategy for strong adherence to metals and high thermal expansion

    Science.gov (United States)

    Thieme, Christian; Rüssel, Christian

    2014-07-01

    Powdered glasses based on the systems BaO/CoO/SiO2 and BaO/ZnO/CoO/SiO2 with small additions of ZrO2, La2O3 and B2O3 were investigated with respect to their sintering and crystallization behavior. They could be fully densified by viscous flow and during subsequent crystallization BaSi2O5 and Ba(ZnxCo2-x)Si2O7 or BaCo2Si2O7 were formed. The CTEs (100-800 °C) of crystallized samples were 14.0-14.6 × 10-6 K-1. Sealing experiments with Nicrofer© alloy showed strong adherence of the crystallized glass. Aluminum from the alloy is oxidized and forms an alumina layer or interconnected structures inside the metal. Cobalt oxide as a component of the glass is reduced to the metal and occurs as approximately spherical particles near the Nicrofer© alloy. The number of cobalt particles increases with increasing sealing temperature. During fracture of sealed Nicrofer© plates, the crack runs through the glass and not through the interface metal/crystallized glass.

  5. Effect of cuprous halide interlayers on the device performance of ZnPc/C{sub 60} organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jinho; Park, Dasom; Heo, Ilsu; Yim, Sanggyu, E-mail: sgyim@kookmin.ac.kr

    2014-10-15

    Highlights: • Effect of CuX interlayers on subsequently deposited films and devices was studied. • CuI is the most effective for the performance of ZnPc/C{sub 60}-based solar cells. • Results were related to the molecular geometry of ZnPc and HOMO level of interlayers. - Abstract: The effect of various cuprous halide (CuX) interlayers introduced between a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) layer and zinc phthalocyanine (ZnPc) layer on the physical properties of the ZnPc thin films and device performances of ZnPc/C{sub 60}-based small-molecule organic solar cells was studied. Strong substrate–molecule interaction between the CuX and ZnPc partly converted surface-perpendicular stacking geometry of ZnPc molecules into surface-parallel one. This flat-lying geometry led to an enhancement in electronic absorption and charge transport within the ZnPc films. As a result, the overall power conversion efficiency of the cell with CuI interlayer increased by ∼37%. In the case of the cells with CuBr and CuCl interlayer, however, the enhancement in device performances was limited because of the reduced conversion of the molecular geometry and increased energy barrier for hole extraction due to the low highest occupied molecular orbital level of the interlayer.

  6. Label-Free Vapor Selectivity in Poly(p-Phenylene Oxide) Photonic Crystal Sensors.

    Science.gov (United States)

    Lova, Paola; Bastianini, Chiara; Giusto, Paolo; Patrini, Maddalena; Rizzo, Paola; Guerra, Gaetano; Iodice, Mario; Soci, Cesare; Comoretto, Davide

    2016-11-23

    The lack of sensors for low cost, extensive, and continuous detection of vapor pollutants is a serious concern for health and safety in industrialized urban areas. Colorimetric sensors, such as distributed Bragg reflectors made of polymers, could achieve this task thanks to their low cost and easy signal transduction but are typically affected by low vapor permeability and lack of selectivity without chemical labeling. Here we demonstrate all-polymer Bragg multilayers for label-free selective detection of organic volatile compounds. The system exploits the ability of amorphous poly(p-phenylene oxide), PPO, to uptake large amount of guest molecules and to form cocrystalline phases with distinct optical properties. Bragg stacks embedding PPO active layers show selective colorimetric response to vapors of carbon tetrachloride and aromatic homologues, which can be revealed by the naked eye.

  7. The study of electron scattering mechanisms in single crystal oxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Berengue, Olivia M; Chiquito, Adenilson J [NanO LaB - Departamento de Fisica, Universidade Federal de Sao Carlos, CEP 13565-905, CP 676, Sao Carlos, Sao Paulo (Brazil); Simon, Ricardo A [UTFPR - Campus Apucarana, Rua MarcIlio Dias, 635, CEP 86812-460, Apucarana, Parana (Brazil); Leite, Edson R, E-mail: oliberengue@yahoo.com.br [Laboratorio Interdisciplinar de EletroquImica e Ceramicas, Departamento de Quimica, Universidade Federal de Sao Carlos, CEP 13565-905, CP 676, Sao Carlos, Sao Paulo (Brazil)

    2011-06-01

    We report on transport measurements of individual Sn doped In{sub 2}O{sub 3} nanowires. From these measurements we point out that spin-orbit and boundary scattering mechanisms seem to give a negligible contribution to the transport of electrons in these nanowires. In fact, these results can be extended to other oxide systems: the presence of a weak disorder arising from the random potential at the boundaries screen electrons away from the surface into the nanowire. Electrons travelling through the nanowire in inner conducting channels are not directly influenced by the surfaces and the boundary scattering is decreased. These findings were also supported by calculations of the electron distribution in the cross-section of the nanowires when some disorder is taken into account.

  8. Crystal Structure and Catalytic Behavior in Olefin Epoxidation of a One-Dimensional Tungsten Oxide/Bipyridine Hybrid.

    Science.gov (United States)

    Amarante, Tatiana R; Antunes, Margarida M; Valente, Anabela A; Paz, Filipe A Almeida; Pillinger, Martyn; Gonçalves, Isabel S

    2015-10-19

    The tungsten oxide/2,2'-bipyridine hybrid material [WO3(2,2'-bpy)]·nH2O (n = 1-2) (1) has been prepared in near quantitative yield by the reaction of H2WO4, 2,2'-bpy, and H2O in the mole ratio of ca. 1:2:700 at 160 °C for 98 h in a rotating Teflon-lined digestion bomb. The solid-state structure of 1 was solved and refined through Rietveld analysis of high-resolution synchrotron X-ray diffraction data collected for the microcrystalline powder. The material, crystallizing in the orthorhombic space group Iba2, is composed of a one-dimensional organic-inorganic hybrid polymer, ∞(1)[WO3(2,2'-bpy)], topologically identical to that found in the previously reported anhydrous phases [MO3(2,2'-bpy)] (M = Mo, W). While in the latter the N,N'-chelated 2,2'-bpy ligands of adjacent corner-shared {MO4N2} octahedra are positioned on the same side of the 1D chain, in 1 the 2,2'-bpy ligands alternate above and below the chain. The catalytic behavior of compound 1 for the epoxidation of cis-cyclooctene was compared with that for several other tungsten- or molybdenum-based (pre)catalysts, including the hybrid polymer [MoO3(2,2'-bpy)]. While the latter exhibits superior performance when tert-butyl hydroperoxide (TBHP) is used as the oxidant, compound 1 is superior when aqueous hydrogen peroxide is used, allowing near-quantitative conversion of the olefin to the epoxide. With H2O2, compounds 1 and [MoO3(2,2'-bpy)] act as sources of soluble active species, namely, the oxodiperoxo complex [MO(O2)2(2,2'-bpy)], which is formed in situ. Compounds 1 and [WO(O2)2(2,2'-bpy)] (2) were further tested in the epoxidation of cyclododecene, trans-2-octene, 1-octene, (R)-limonene, and styrene. The structure of 2 was determined by single-crystal X-ray diffraction and found to be isotypical with the molybdenum analogue.

  9. Crystal structure and electrical properties of gadolinia doped bismuth oxide nanoceramic powders

    Energy Technology Data Exchange (ETDEWEB)

    Ar Latin-Small-Letter-Dotless-I , M. [Physics Department, Faculty of Sciences, Erciyes University, Kayseri (Turkey); Tasc Latin-Small-Letter-Dotless-I oglu, I.; Alt Latin-Small-Letter-Dotless-I ndal, S. [Physics Department, Faculty of Arts and Sciences, Gazi University, Ankara (Turkey); Uslu, I.; Aytimur, A. [Department of Chemistry Education, Gazi University, Ankara (Turkey); Karaaslan, T. [Physics Department, Faculty of Sciences, Erciyes University, Kayseri (Turkey); Kocyigit, S., E-mail: sergas_29@hotmail.com [Department of Chemistry Education, Gazi University, Ankara (Turkey)

    2012-10-15

    A novel method of fabrication of gadolinia doped bismuth oxide nanoceramic via the sol-gel technique is reported. Their thermal, structural and morphological properties are described by measurements of Differential Thermal Analysis/Thermal Gravimetry, X-ray Powder Diffraction and Scanning Electron Microscopy. The samples have stable high ion conductive face centered cubic {delta}-phase nanocrystalline structure. The electrical measurements of the nanoceramic powders were carried out in the temperature range of (689-1091 K) using 4-point probe technique. There is a transition between two distinct regions at 720 Degree-Sign C, which can be attributed to the order-disorder transition. This observation is supported by the differential thermal analysis measurements. The experimental results show that the value of conductivity increases with increasing temperature over linear parts characterized by two different activation energies. The conductivity data over whole measured temperature range were fitted to the Arrhenius equations of conductivity and it shows two linear regions with different slopes which correspond to low-temperature range (689-975 K) and high-temperature range (999-1091 K). The values of E{sub a1} and E{sub a2} were obtained from the slopes of ln {sigma}{sub DC} versus q/kT plot as 1.25 eV and 2.81 eV for low-temperature range and high-temperature range, respectively. -- Highlights: Black-Right-Pointing-Pointer Gadolinia doped bismuth oxide nanoceramic were produced via the sol-gel technique. Black-Right-Pointing-Pointer Structural characterizations were carried out by XRD and SEM techniques. Black-Right-Pointing-Pointer Thermal and electrical properties were evaluated by DTA/TG and 4-point probe. Black-Right-Pointing-Pointer Crystallite size was calculated using Scherrer equation. Black-Right-Pointing-Pointer The dislocation density, the microstrain and unit cell volume were calculated.

  10. Reduction of Resistivity in Cu Thin Films by Partial Oxidation: Microstructural Mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Prater, W

    2003-10-14

    We report the electrical resistance and microstructure of sputter deposited copper thin films grown in an oxygen containing ion-beam sputtering atmosphere. For films thinner than 5 nm, 2-10% oxygen causes a decrease in film resistance, while for thicker films there is a monotonic increase in resistivity. X-ray reflectivity measurements show significantly smoother films for these oxygen flow rates. X-ray diffraction shows that the oxygen doping causes a refinement of the copper grain size and the formation of cuprous oxide. We suggest that the formation of cuprous oxide limits copper grain growth, which causes smoother interfaces, and thus reduces resistivity by increasing specular scattering of electrons at interfaces.

  11. Perspective: Maintaining surface-phase purity is key to efficient open air fabricated cuprous oxide solar cells

    Directory of Open Access Journals (Sweden)

    Robert L. Z. Hoye

    2015-02-01

    Full Text Available Electrochemically deposited Cu2O solar cells are receiving growing attention owing to a recent doubling in efficiency. This was enabled by the controlled chemical environment used in depositing doped ZnO layers by atomic layer deposition, which is not well suited to large-scale industrial production. While open air fabrication with atmospheric pressure spatial atomic layer deposition overcomes this limitation, we find that this approach is limited by an inability to remove the detrimental CuO layer that forms on the Cu2O surface. Herein, we propose strategies for achieving efficiencies in atmospherically processed cells that are equivalent to the high values achieved in vacuum processed cells.

  12. Cuprous Oxide as a Potential Low-Cost Hole-Transport Material for Stable Perovskite Solar Cells.

    Science.gov (United States)

    Nejand, Bahram Abdollahi; Ahmadi, Vahid; Gharibzadeh, Saba; Shahverdi, Hamid Reza

    2016-02-08

    Inorganic hole-transport materials are commercially desired to decrease the fabrication cost of perovskite solar cells. Here, Cu2O is introduced as a potential hole-transport material for stable, low-cost devices. Considering that Cu2O formation is highly sensitive to the underlying mixture of perovskite precursors and their solvents, we proposed and engineered a technique for reactive magnetron sputtering. The rotational angular deposition of Cu2O yields high surface coverage of the perovskite layer for high rate of charge extraction. Deposition of this Cu2O layer on the pinhole-free perovskite layer produces devices with power conversion efficiency values of up to 8.93%. The engineered Cu2O layers showed uniform, compact, and crack-free surfaces on the perovskite layer without affecting the perovskite structure, which is desired for deposition of the top metal contact and for surface shielding against moisture and mechanical damages. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Ionic strength assay via polyacrylate-ferriferrous oxide magnetic photonic crystals.

    Science.gov (United States)

    Li, Yan-Ran; Sun, Ye; Wang, He-Fang

    2015-05-21

    Convenient reading out and/or determination of ionic strength (IS) is of great significance for both scientific research and real life applications. We presented here a novel method for the rapid and sensitive IS assay based on the electrolyte-induced sensitive wavelength blueshifts of the reflection spectra of polyacrylate capped Fe3O4 magnetic photonic crystals (PA-Fe3O4-MPCs). For HCl, MgSO4 and the common electrolytes corresponding to the salinity of seawater (including NaCl, KCl, MgCl2, CaCl2, Na2SO4 and their mixtures), the PA-Fe3O4-MPCs displayed wavelength blueshifts identical to the total IS of the aqueous solutions, regardless of the kind of above-mentioned electrolytes in the solutions. Besides, the PA-Fe3O4-MPCs exhibited relatively high sensitivity (an average of 294 nm L mmol(-1) in the range of 0.05-0.30 mmol L(-1), and an even higher value of 386 nm L mmol(-1) at 0.05-0.15 mmol L(-1)) and fast response (within 8 s) to the IS of aqueous solutions. The relative standard deviation (RSD) for IS (NaCl, 0.1 mmol L(-1)) was 4.4% (n = 5). The developed method was applied to determine the salinity of seawater samples, and the determined results were validated by the traditional standard chlorinity titration and electric conductimetry method. The recoveries were in the range of 92-104%. The proposed PA-Fe3O4-MPCs based reflectometry method would have great potential for IS and salinity assays.

  14. The impact of crystal symmetry on the electronic structure and functional properties of complex lanthanum chromium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Liang [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Xiao, Haiyan Y. [Univ. of Tennessee, Knoxville, TN (United States); Heald, Steve M. [Argonne National Lab. (ANL), Argonne, IL (United States); Bowden, Mark E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Varga, Tamas [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Exarhos, Gregory J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Biegalski, Michael D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ivanov, Ilia N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Weber, William J. [Univ. of Tennessee, Knoxville, TN (United States); Droubay, Timothy C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Chambers, Scott A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-06-14

    Complex oxides exhibit a wide range of crystal structures, chemical compositions and physical properties. The underlying drivers determining the complicated structure-composition-property phase diagrams are the relative positions and orbital overlaps between the metal cations and the oxygen anions. Here we report a combined experimental and theoretical investigation of the structure and bonding in a series of lanthanum chromium oxides prepared by reactive molecular beam epitaxy. Of particular interest is the charge state and local coordination of the Cr. We have stabilized LaCrO3, LaCrO4 and La2CrO6 films by controlling the three elemental fluxes during deposition, and have carried out x-ray diffraction, x-ray photoemission, and x-ray absorption spectroscopy, as well as first-principles calculations, to determine structure, charge state, chemical bonding, and electronic structure. Significant changes in bonding character and orbital interaction are revealed with decreasing ligand symmetry from octahedral to tetrahedral Cr coordination. Both LaCrO4 and LaCrO6 with tetrahedrally coordinated Cr show strong pre-edge features in the Cr K-edge near-edge structure whereas LaCrO3 with octahedrally coordinated Cr exhibits very weak pre-edge features. The origin of these pre-edge features is discussed based on various selection rules and ligand symmetry. We also demonstrate an increase in cation-anion orbital hybridization and a decrease in long-range ligand coupling induced by this symmetry reduction. These in turn result in dramatic modifications of the macroscopic optical and magnetic properties.

  15. Nano-crystals of cerium–hafnium binary oxide: Their size-dependent structure

    Energy Technology Data Exchange (ETDEWEB)

    Raitano, Joan M. [Department of Applied Physics and Applied Mathematics, Materials Science and Engineering Program, Columbia University, New York, NY 10027 (United States); Khalid, Syed [National Synchrotron Light Source, Brookhaven National Laboratory, Upton, NY 11973 (United States); Marinkovic, Nebojsa [Chemical Engineering Department, Columbia University, 500 W 120th St, Mudd 801, New York, NY 10027 (United States); Chan, Siu-Wai, E-mail: sc174@columbia.edu [Department of Applied Physics and Applied Mathematics, Materials Science and Engineering Program, Columbia University, New York, NY 10027 (United States)

    2015-09-25

    Highlights: • (1 − x)CeO{sub 2}–xHfO{sub 2} was precipitated (0 < x < 1) and calcined in air. • For x ⩽ 0.14, crystallites ⩽140 nm in size exhibit only the fluorite structure. • This low hafnia solubility is attributable to no auto-reduction (Ce{sup 3+} = 0). • The low solubility is also due to the high temperature required for homogenization. • Coarsening is lessened as Hf{sup 4+} ions slow cation diffusion in these crystallites. - Abstract: Cerium oxide (CeO{sub 2}, “ceria”) and hafnium oxide (HfO{sub 2}, “hafnia”) were aqueously co-precipitated and subsequently calcined to allow for homogenization. The size of the (1−x)CeO{sub 2}–xHfO{sub 2} crystallites, determined by the Scherrer equation, varied from 140 nm for x = 0 to 15 nm for x = 0.73. For x ⩽ 0.14, only cubic structures are visible in X-ray diffractograms, and the lattice parameters are consistent with the values expected for structurally cubic solid solutions of hafnia in ceria. At x = 0.26, tetragonal and monoclinic phases nucleated with the former not being observed in the bulk phase diagram for ceria–hafnia. Therefore, the solubility limit of the cubic structure is between x = 0.14 and x = 0.26 for 40–61 nm crystallites, the sizes of these respective compositions. More specifically, for the 40 nm crystallites of x = 0.26 (1 − x)CeO{sub 2}–xHfO{sub 2}, 15% of the hafnia remains in a structurally cubic solid solution with ceria based on the observed cubic lattice parameter. The compositional domain for the cubic fluorite structure in this study is narrower than other nanostructured (1 − x)CeO{sub 2}–xHfO{sub 2} studies, especially studies with crystallite sizes less than 10 nm, but wider than observed in the bulk and helps to expand the size regime over which the relationship between crystallite size and phase stability is known. The extent of this cubic-structure domain is mainly attributable to the intermediate crystallite size and the roughly zero Ce{sup 3

  16. Synthesis and characterization of different metal oxide nanostructures by simple electrolysis based oxidation of metals.

    Science.gov (United States)

    Singh, Dinesh Pratap; Srivastava, Onkar Nath

    2009-09-01

    We report the Synthesis of different metal oxide (Cu2O, SnO2, Fe3O4 and PbO2) nanostructures by simple electrolysis based oxidation of metals (Cu, Sn, Fe and Pb). We have utilized the two electrode set up for the electrolysis and used different metal electrodes as anode and platinum as cathode. The synthesized nanomaterials were delaminated in the electrolyte. The microstructural characterization of synthesized materials in electrolytes after electrolysis at different electrode potentials revealed that the nanostructures strongly depend on the applied voltage between the electrodes. Various nanostructures (nanothreads, nanowires, nanocubes, nanotetrapods and hexagons-like) of metal oxides have been synthesized by this method. In case of copper electrode we have found nanothreads and nanowires of cuprous oxide. Tin electrode resulted nanothreads, nanotetrapod and nanocube like structures of tin oxide. Iron electrode resulted, nanowire like structures of iron oxide and lead sheet transformed into hexagon like and six petals like structures of lead oxide.

  17. Oxidation of Octopus vulgaris hemocyanin by nitrogen oxides

    Energy Technology Data Exchange (ETDEWEB)

    Salvato, B.; Giacometti, G.M.; Beltramini, M.; Zilio, F.; Giacometti, G.; Magliozzo, R.S.; Peisach, J.

    1989-01-24

    The reaction of Octopus vulgaris hemocyanin with nitrite was studied under a variety of conditions in which the green half-met derivative is formed. Analytical evidence shows that the amount of chemically detectable nitrite in various samples of the derivative is not proportional to the cupric copper detected by EPR. The kinetics of oxidation of hemocyanin as a function of protein concentration and pH, in the presence of nitrite and ascorbate, is consistent with a scheme in which NO/sub 2/ is the reactive oxidant. We suggest that the green half-methemocyanin contains a metal center with one cuprous and one cupric copper without an exogenous nitrogen oxide ligand.

  18. DFT Study of Effects of Potassium Doping on Band Structure of Crystalline Cuprous Azide

    Institute of Scientific and Technical Information of China (English)

    ZHU,Wei-Hua; ZHANG,Xiao-Wen; WEI,Tao; XIAO,He-Ming

    2008-01-01

    The structure and defect formation energies of the K-doped CuN3 were studied using density functional theory within the generalized gradient approximation. The results show that the K-doping breaks the azide symmetry and causes asymmetric atomic displacement. As the K-doping level increases, the band gap of the doped system gradually increases. The K impurity is easily incorporated into the crystal thermodynamically. The Cu vacancy is easily created thermodynamically and the K impurity can serve as nucleation centers for vacancy clustering. Finally the effects of K-doping concentrations on the sensitivity of CuN3 were understood based on electronic structures.

  19. Oxidation behavior and mechanism of a Ni-based single crystal superalloy with single α-Al2O3 film at 1000 °C

    Science.gov (United States)

    Pei, Haiqing; Wen, Zhixun; Zhang, Yamin; Yue, Zhufeng

    2017-07-01

    Detailed long-term of 2000 h oxidation behavior of a Ni-based single crystal superalloy was investigated at 1000 °C. In the first oxidation stage, α-Al2O3 formed immediately, and then the mass gain curve obeys the parabolic law, which corresponds to the growth of α-Al2O3 film. A single α-Al2O3 film kept on the surface of the specimen before 750 h oxidation. The oxidation is controlled by the inward diffusion of oxygen anions to react with Al cations at the oxide/metal interface. The shape of the exfoliation region of single α-Al2O3 film is closed to an annulus, in which the (Ni, Co)O layer formed due to depletion of Al. The three-layer oxide scale formed rapidly after 750 h oxidation. With the continue consumption of Al, a discontinuous inner α-Al2O3 layer formed, making oxide scale spall seriously and gain mass rapidly. The states of α-Al2O3 film, the controlled film, are different in dendrite core and interdendritic region.

  20. Wide Spectral Characteristics of Si Photonic Crystal Mach-Zehnder Modulator Fabricated by Complementary Metal-Oxide-Semiconductor Process

    Directory of Open Access Journals (Sweden)

    Yosuke Hinakura

    2016-04-01

    Full Text Available Optical modulators for optical interconnects require a small size, small voltage, high speed and wide working spectrum. For this purpose, we developed Si slow-light Mach-Zehnder modulators via a 180 nm complementary metal-oxide-semiconductor process. We employed 200 μm lattice-shifted photonic crystal waveguides with interleaved p-n junctions as phase shifters. The group index spectrum of slow light was almost flat at ng ≈ 20 but exhibited ±10% fluctuation over a wavelength bandwidth of 20 nm. The cutoff frequency measured in this bandwidth ranged from 15 to 20 GHz; thus, clear open eyes were observed in the 25 Gbps modulation. However, the fluctuation in ng was reflected in the extinction ratio and bit-error rate. For a stable error-free operation, a 1 dB margin is necessary in the extinction ratio. In addition, we constructed a device with varied values of ng and confirmed that the extinction ratio at this speed was enhanced by larger ng up to 60. However, this larger ng reduced the cutoff frequency because of increased phase mismatch between slow light and radio frequency signals. Therefore, ng available for 25 Gbps modulation is limited to up to 40 for the current device design.

  1. Synthesis of bismuth (III oxide films based anodes for electrochemical degradation of reactive blue 19 and crystal violet

    Directory of Open Access Journals (Sweden)

    Petrović Milica M.

    2014-01-01

    Full Text Available The Bi2O3 films-based anodes were synthesized by electrodeposition of Bi on stainless steel substrate at constant current density and during different deposition times, fallowed by calcination, forming Bi2O3. The thickness of the films was determined by two methods: the observation under the microscope and by calculation from mass difference. Electrochemical proceses at the anodes were ivestigated by linear sweep voltammetry. At the anodes obtained within 2, 5, 10 and 15 minutes of deposition, two dyes, namely: Reactive Blue 19 and Crystal Violet, were decolorized by oxidation with •OH radical, generated from H2O2 decomposition at the anodes. Decoloration times of the anodes varied, and the shortest one was achieved with the anode obtained during 5 minutes of deposition, with the film thickness of 2.5±0.3 μm. The optimal H2O2 concentration for the dyes degradation was found to be 10 mmol dm-3. [Projekat Ministarstva nauke Republike Srbije, br. ТR 34008

  2. Fragment size for calculations on alkaline-earth oxides by the crystal cluster SCF-X/sub approx. /-RW method

    Energy Technology Data Exchange (ETDEWEB)

    Lobach, V.A.; Sobolev, A.B.; Shul' gin, B.V.

    1987-05-01

    Calculations have been performed on the clusters (A/sub x/B/sub y/) (x = 1, 13; y = 6, 14), corresponding to perfect crystals of the alkaline-earth oxides (AEO) MgO, CaO, and SrO by means of methods involving molecular clusters (MC) and crystalline clusters (CC) in the SCF-X/sub approx./-RW method. It is found that MC is unsuitable for describing perfect AEO, because they have a long-range Coulomb interaction and a potential cluster effect. Even in the CC method, the nonstoichiometric composition of (A/sub x/B/sub y/) for x < 13 and y < 14 does not allow one to obtain satisfactory agreement with the observed optical and x-ray spectra. The (A/sub 13/B/sub 14/) and (B/sub 13/A/sub 14/) clusters reproduce satisfactorily the partial composition of the valence band (VB) and the conduction band (CB), as well as the widths of those bands, the fine structure of the K emission spectrum for oxygen in MgO, and the observed electron-density distribution. A study is made of the effects of varying the radii of the spheres on the error from the region between the spheres with muffin-tin averaging.

  3. Ultra-sensitive detection of zinc oxide nanowires using a quartz crystal microbalance and phosphoric acid DNA

    Science.gov (United States)

    Jang, Kuewhan; You, Juneseok; Park, Chanhoo; Park, Hyunjun; Choi, Jaeyeong; Choi, Chang-Hwan; Park, Jinsung; Lee, Howon; Na, Sungsoo

    2016-09-01

    Recent advancements of nanomaterials have inspired numerous scientific and industrial applications. Zinc oxide nanowires (ZnO NWs) is one of the most important nanomaterials due to their extraordinary properties. However, studies performed over the past decade have reported toxicity of ZnO NWs. Therefore, there has been increasing demand for effective detection of ZnO NWs. In this study, we propose a method for the detection of ZnO NW using a quartz crystal microbalance (QCM) and DNA probes. The detection method is based on the covalent interaction between ZnO NWs and the phosphoric acid group of single-stranded DNA (i.e., linker DNA), and DNA hybridization between the linker DNA and the probe DNA strand on the QCM electrode. Rapid, high sensitivity, in situ detection of ZnO NWs was demonstrated for the first time. The limit of detection was 10-4 μg ml-1 in deionized water, which represents a sensitivity that is 100000 times higher than the toxic ZnO NW concentration level. Moreover, the selectivity of the ZnO NW detection method was demonstrated by comparison with other types of nanowires and the method was able to detect ZnO NWs in tap water sensitively even after stored for 14 d in a refrigerator. The performance of our proposed method was sufficient to achieve detection of ZnO NW in the ‘real-world’ environment.

  4. Passively mode-locked fiber laser based on a hollow-core photonic crystal fiber filled with few-layered graphene oxide solution.

    Science.gov (United States)

    Liu, Zhi-Bo; He, Xiaoying; Wang, D N

    2011-08-15

    We demonstrate a nanosecond-pulse erbium-doped fiber laser that is passively mode locked by a hollow-core photonic crystal fiber filled with few-layered graphene oxide solution. Owing to the good solution processing capability of few-layered graphene oxide, which can be filled into the core of a hollow-core photonic crystal fiber through a selective hole filling process, a graphene saturable absorber can be successfully fabricated. The output pulses obtained have a center wavelength, pulse width, and repetition rate of 1561.2 nm, 4.85 ns, and 7.68 MHz, respectively. This method provides a simple and efficient approach to integrate the graphene into the optical fiber system.

  5. Freeform Fabrication of Magnetophotonic Crystals with Diamond Lattices of Oxide and Metallic Glasses for Terahertz Wave Control by Micro Patterning Stereolithography and Low Temperature Sintering

    Directory of Open Access Journals (Sweden)

    Maasa Nakano

    2013-04-01

    Full Text Available Micrometer order magnetophotonic crystals with periodic arranged metallic glass and oxide glass composite materials were fabricated by stereolithographic method to reflect electromagnetic waves in terahertz frequency ranges through Bragg diffraction. In the fabrication process, the photo sensitive acrylic resin paste mixed with micrometer sized metallic glass of Fe72B14.4Si9.6Nb4 and oxide glass of B2O3·Bi2O3 particles was spread on a metal substrate, and cross sectional images of ultra violet ray were exposed. Through the layer by layer stacking, micro lattice structures with a diamond type periodic arrangement were successfully formed. The composite structures could be obtained through the dewaxing and sintering process with the lower temperature under the transition point of metallic glass. Transmission spectra of the terahertz waves through the magnetophotonic crystals were measured by using a terahertz time domain spectroscopy.

  6. Comparison of formic acid oxidation at supported Pt catalyst and at low-index Pt single crystal electrodes in sulfuric acid solution

    Directory of Open Access Journals (Sweden)

    AMALIJA V. TRIPKOVIC

    2003-11-01

    Full Text Available The oxidation of formic acid was studied at supported Pt catalyst (47.5 wt%. Pt and a low-index single crystal electrodes in sulfuric acid. The supported Pt catalyst was characterized by the TEM and HRTEM techniques. The mean Pt particle diameter, calculated from electrochemical measurements, fits well with Pt particle size distribution determined by HRTEM. For the mean particle diameter the surface averaged distribution of low-index single crystal facets was established. Comparison of the activities obtained at Pt supported catalyst and low-index Pt single crystal electrodes revealed that Pt(111 plane is the most active in the potential region relevant for fuel cell applications.

  7. Oxidative stress by monosodium urate crystals promotes renal cell apoptosis through mitochondrial caspase-dependent pathway in human embryonic kidney 293 cells: mechanism for urate-induced nephropathy.

    Science.gov (United States)

    Choe, Jung-Yoon; Park, Ki-Yeun; Kim, Seong-Kyu

    2015-01-01

    The aim of this study is to clarify the effect of oxidative stress on monosodium urate (MSU)-mediated apoptosis of renal cells. Quantitative real-time polymerase chain reaction and immunoblotting for Bcl-2, caspase-9, caspase-3, iNOS, cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), IL-18, TNF receptor-associated factor-6 (TRAF-6), and mitogen-activated protein kinases were performed on human embryonic kidney 293 (HEK293) cells, which were stimulated by MSU crystals. Fluorescence-activated cell sorting was performed using annexin V for assessment of apoptosis. Reactive oxygen species (ROS) were measured. IL-1β siRNA was used for blocking IL-1β expression. MSU crystals promoted ROS, iNOS, and COX-2 expression and also increased TRAF-6 and IL-1β expression in HEK293 cells, which was inhibited by an antioxidant ascorbic acid. Caspase-dependent renal cell apoptosis was induced through attenuation of Bcl-2 and enhanced caspase-3 and caspase-9 expression by MSU crystals, which was significantly reversed by ascorbic acid and transfection of IL-1β siRNA to HEK293 cells. Ascorbic acid inhibited phosphorylation of extracellular signal-regulated kinase and Jun N-terminal protein kinase stimulated by MSU crystals. ROS accumulation and iNOS and COX-2 mRNA expression by MSU crystals was also suppressed by transfection with IL-1β siRNA. Oxidative stress generated by MSU crystals promotes renal apoptosis through the mitochondrial caspase-dependent apoptosis pathway.

  8. Annealing behaviour and crystal structure of RF-sputtered Bi-substituted dysprosium iron-garnet films having excess co-sputtered Bi-oxide content

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliev, M; Nur-E-Alam, M; Alameh, K [Electron Science Research Institute, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA, 6027 (Australia); Premchander, P; Lee, Y T [Department of Information and Communications, Gwangju Institute of Science and Technology (GIST), Gwangju, 500-712 (Korea, Republic of); Kotov, V A [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 11 Mohovaya St, Moscow, 125009 (Russian Federation); Lee, Y P, E-mail: m.vasiliev@ecu.edu.au [Quantum Photonic Science Research Center, Department of Physics, Hanyang University, 133-791 (Korea, Republic of)

    2011-02-23

    We investigate the magneto-optic properties, crystal structure and annealing behaviour of nano-composite media with record-high magneto-optic quality exceeding the levels reported so far in sputtered iron-garnet films. Bi-substituted dysprosium-gallium iron-garnet films having excess bismuth oxide content are deposited using RF co-sputtering, and a range of garnet materials are crystallized using conventional oven-annealing processes. We report, for the first time ever, the results of optimization of thermal processing regimes for various high-performance magneto-optic iron-garnet compositions synthesized and describe the evolution of the optical and magneto-optical properties of garnet-Bi-oxide composite-material films occurring during the annealing processes. The crystallization temperature boundaries of the system (BiDy){sub 3}(FeGa){sub 5}O{sub 12} : Bi{sub 2}O{sub 3} are presented. We also report the results of x-ray diffraction and energy-dispersive x-ray spectroscopy studies of this recently developed class of high-performance magneto-optic composites. Our hypothesis of iron oxides being the cause of excess optical absorption in sputtered Bi-iron-garnet films is confirmed experimentally.

  9. Influence of Phase Transformations on Crystal Growth of Stoichiometric Brownmillerite Oxides: Sr2ScGaO5 and Ca2Fe2O5

    Directory of Open Access Journals (Sweden)

    Monica Ceretti

    2016-11-01

    Full Text Available High quality stoichiometric brownmillerite-type oxide single crystals have been successfully grown by the floating zone method using a mirror furnace. We report here on the growth conditions and structural characterization of two model compounds: Ca2Fe2O5 and Sr2ScGaO5. Both show oxygen deficiency with respect to the average perovskite structure, and are promising candidates for oxygen ion conductivity at moderate temperatures. While Sr2ScGaO5 single crystals were obtained in the cubic oxygen-deficient perovskite structure, Ca2Fe2O5 crystallizes in the brownmillerite framework. Having no cubic parent high temperature counterpart, Ca2Fe2O5 crystals were found to be not twinned. We report on structural characterization of the as-grown single crystals by neutron and X-ray diffraction, as well as scanning electron microscopy (SEM coupled with EDX (Energy Dispersive X-Ray Spectroscopy analysis and isotope exchange experiments.

  10. Slow photon amplification of gas-phase ethanol photo-oxidation in titania inverse opal photonic crystals

    Science.gov (United States)

    Jovic, Vedran; Idriss, Hicham; Waterhouse, Geoffrey I. N.

    2016-11-01

    Here we describe the successful fabrication of six titania inverse opal (TiO2 IO) photocatalysts with fcc[1 1 1] pseudo photonic band gaps (PBGs) tuned to span the UV-vis region. Photocatalysts were fabricated by a colloidal crystal templating and sol-gel approach - a robust and highly applicable bottom-up scheme which allowed for precise control over the geometric and optical properties of the TiO2 IO photocatalysts. Optical properties of the TiO2 IO thin films were investigated in detail by UV-vis transmittance and reflectance measurements. The PBG along the fcc[1 1 1] direction in the TiO2 IOs was dependent on the inter-planar spacing in the [1 1 1] direction, the incident angle of light and the refractive index of the medium filling the macropores in the IOs, in agreement with a modified Bragg's law expression. Calculated photonic band structures for the photocatalysts revealed a PBG along the Γ → L direction at a/λ ∼ 0.74, in agreement with the experimental optical data. By coupling the low frequency edge of the PBG along the [1 1 1] direction with the electronic absorption edge of anatase TiO2, a two-fold enhancement in the rate of gas phase ethanol photo-oxidation in air was achieved. This enhancement appears to be associated with a 'slow photon' effect that acts to both enhance TiO2 absorption and inhibit spontaneous emission (i.e. suppress electron-hole pair recombination).

  11. Electrochemical quartz crystal microbalance study on Au-supported Pt adlayers for electrocatalytic oxidation of methanol in alkaline solution

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Underpotential deposition(UPD) of Cu on an Au electrode followed by redox replacement reaction(RRR) of CuUPD with a Pt source(H2PtCl6 or K2PtCl4) yielded Au-supported Pt adlayers(for short,Pt(CuUPD-Pt4+)n/Au for H2PtCl6,or Pt(CuUPD-Pt2+)n/Au for K2PtCl4,where n denotes the number of UPD-redox replacement cycles).The electrochemical quartz crystal microbalance(EQCM) technique was used for the first time to quantitatively study the fabricated electrodes and estimate their mass-normalized specific electrocatalytic activity(SECA) for methanol oxidation in alkaline solution.In comparison with Pt(CuUPD-Pt2+)n/Au,Pt(CuUPD-Pt4+)n/Au exhibited a higher electrocatalytic activity,and the maximum SECA was obtained to be as high as 35.7 mA ?g?1 at Pt(CuUPD-Pt4+)3/Au.The layer-by-layer architecture of Pt atoms on Au is briefly discussed based on the EQCM-revealed redox replacement efficiency,and the calculated distribution percentages of bare Au sites agree with the experimental results deduced from the charge under the AuOx-reduction peaks.The EQCM is highly recommended as an efficient technique to quantitatively examine various electrode-supported catalyst adlayers,and the highly efficient catalyst adlayers of noble metals are promising in electrocatalysis relevant to biological,energy and environmental sciences and technologies.

  12. A novel dinuclear schiff base copper complex as an efficient and cost effective catalyst for oxidation of alcohol: Synthesis, crystal structure and theoretical studies

    Indian Academy of Sciences (India)

    Atena Naeimi; Samira Saeednia; Mehdi Yoosefian; Hadi Amiri Rudbari; Viviana Mollica Nardo

    2015-07-01

    An environmentally friendly protocol is described for an economic, practical laboratory-scale oxidation of primary and secondary alcohols to aldehydes and ketones, using a bis-chloro-bridged binuclear Cu(II) complex [(HL)Cu(2-Cl)2Cu(HL)]*1.5 CH3OH as catalyst. The catalyst was prepared in situ from commercially available reagents and is characterized by single crystal X-ray analysis, FT-IR, UV-visible spectra, mass spectrometry, and powder x-ray diffraction (PXRD). The geometry of the complex has been optimized using the B3LYP level of theory confirming the experimental data. Our results demonstrated well the efficiency, selectivity and stability of this new catalyst in the oxidation of alcohols in ethanol and tert-butyl hydroperoxide (tBuOOH) as a green solvent and oxidant, respectively. Turnover number and reusability have proven the high efficiency and relative stability of the catalyst.

  13. Crystallization and preliminary X-ray analysis of human MTH1 complexed with two oxidized nucleotides, 8-oxo-dGMP and 2-oxo-dATP

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Teruya; Kitaguchi, Yuki; Miyazawa, Masayuki [Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973 (Japan); Kamiya, Hiroyuki [Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812 (Japan); Toma, Sachiko; Ikemizu, Shinji [Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973 (Japan); Shirakawa, Masahiro [Graduate School of Engineering, Kyoto University, Kyoto 615-8510 (Japan); Nakabeppu, Yusaku [Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582 (Japan); Yamagata, Yuriko, E-mail: yamagata@gpo.kumamoto-u.ac.jp [Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973 (Japan)

    2006-12-01

    The complexes of human MTH1 with two oxidized nucleotides, 8-oxo-dGMP and 2-oxo-dATP, were crystallized. The crystals diffracted to 1.95 and 2.22 Å resolution, respectively. Human MutT homologue 1 (hMTH1) hydrolyzes a variety of oxidized purine nucleoside triphosphates, including 8-oxo-dGTP, 2-oxo-dATP, 2-oxo-ATP and 8-oxo-dATP, to their corresponding nucleoside monophosphates, while Esherichia coli MutT possesses prominent substrate specificity for 8-oxoguanine nucleotides. Three types of crystals were obtained corresponding to the following complexes: selenomethionine-labelled hMTH1 with 8-oxo-dGMP (SeMet hMTH1–8-oxo-dGMP), hMTH1 with 8-oxo-dGMP (hMTH1–8-oxo-dGMP) and hMTH1 with 2-oxo-dATP (hMTH1–2-oxo-dATP). Crystals of the SeMet hMTH1–8-oxo-dGMP complex belong to space group P4{sub 1}2{sub 1}2, with unit-cell parameters a = b = 45.8, c = 153.6 Å, and diffracted to 2.90 Å. Crystals of hMTH1–8-oxo-dGMP and hMTH1–2-oxo-dATP belong to space groups P2{sub 1} and P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 34.0, b = 59.0, c = 65.9 Å, β = 90.7° and a = 59.2, b = 67.3, c = 80.0 Å, respectively. Their diffraction data were collected at resolutions of 1.95 and 2.22 Å, respectively.

  14. Zisheng Shenqi decoction ameliorates monosodium urate crystal-induced gouty arthritis in rats through anti-inflammatory and anti-oxidative effects.

    Science.gov (United States)

    Han, Jieru; Xie, Ying; Sui, Fangyu; Liu, Chunhong; Du, Xiaowei; Liu, Chenggang; Feng, Xiaoling; Jiang, Deyou

    2016-09-01

    Based on traditional Chinese medicinal theories on gouty arthritis, Zisheng Shenqi decoction (ZSD), a novel Chinese medicinal formula, was developed due to its multiple functions, including reinforcing renal function, promoting blood circulation and relieving pain. In the present study, the effect of ZSD on monosodium urate (MSU) crystal-induced gouty arthritis in rats was investigated and the underlying mechanisms were examined. The data from these investigations showed that the injection of MSU crystals into the ankle joint cavity caused significant elevations in ankle swelling and inflammatory cell infiltration into the synovium, whereas these abnormal changes were markedly suppressed by oral administration of ZSD (40 mg/kg) for 7 days. Mechanically, ZSD treatment prevented MSU crystal‑induced inflammatory responses, as evidenced by downregulation in the expression levels of NACHT domain, leucine‑rich repeat and pyrin domain containing protein (NALP) 1 and NALP6 inflammasomes, decreased serum levels of tumor necrosis factor‑α and interleukin‑1β, and inhibited activation of nuclear factor‑κB. In addition, ZSD administration markedly enhanced the anti-oxidant status in MSU crystal‑induced rats by the increase in the activities of superoxide dismutase and glutathione peroxidase, and the levels of reduced glutathione. These results indicated that ZSD effectively prevented MSU crystal-induced gouty arthritis via modulating multiple anti‑oxidative and anti‑inflammatory pathways, suggesting a promising herbal formula for the prevention and treatment of gouty arthritis.

  15. Growth and characterization of single phase Cu2O by thermal oxidation of thin copper films

    Science.gov (United States)

    Choudhary, Sumita; Sarma, J. V. N.; Gangopadhyay, Subhashis

    2016-04-01

    We report a simple and efficient technique to form high quality single phase cuprous oxide films on glass substrate using thermal evaporation of thin copper films followed by controlled thermal oxidation in air ambient. Crystallographic analysis and oxide phase determination, as well as grain size distribution have been studied using X-ray diffraction (XRD) method, while scanning electron microscopy (SEM) has been utilized to investigate the surface morphology of the as grown oxide films. The formation of various copper oxide phases is found to be highly sensitive to the oxidation temperature and a crystalline, single phase cuprous oxide film can be achieved for oxidation temperatures between 250°C to 320°C. Cu2O film surface appeared in a faceted morphology in SEM imaging and a direct band gap of about 2.1 eV has been observed in UV-visible spectroscopy. X-ray photoelectron spectroscopy (XPS) confirmed a single oxide phase formation. Finally, a growth mechanism of the oxide film has also been discussed.

  16. Synthesis and Crystal Structure of 2-Ethoxy-spiro[2H-1, 4,2-benzoxazaphosphorine-3(4H), 1'-Cycloheptane] 2-Oxide

    Institute of Scientific and Technical Information of China (English)

    WANG Bin; CHEN Ru-Yu; HUANG You; MIAO Zhi-Wei

    2006-01-01

    The title compound 2-ethoxy-spiro[2H-1,4,2-benzoxazaphosphorine-3(4H),1'-cyc- loheptane] 2-oxide (C15H22NO3P) was synthesized by the Mannich-type reaction of o-amino-phenol with ethyl dichlorophosphinite and cycloheptanone, and structurally characterized by single-crystal X-ray diffraction analysis. It crystallizes in orthorhombic, space group P212121 with a = 8.9840(12), b = 9.2978(12), c = 37.205(5)(A), V = 3107.8(7)(A)3, Z = 8, Mr = 295.31, Dc = 1.262 g/cm3, F(000) = 1264, μ = 0.184 mm-1, S = 1.026, the final R = 0.0502 and wR = 0.1017 for 3849 observed reflections with I > 2σ(I) and 378 variable parameters. The structure exhibits that the six-membered phosphorus heterocycle is in the envelope conformation.

  17. Compression of single-crystal magnesium oxide to 118 GPa and a ruby pressure gauge for helium pressure media

    Science.gov (United States)

    Jacobsen, S. D.; Holl, C. M.; Adams, K. A.; Fischer, R. A.; Martin, E. S.; Bina, C. R.; Lin, J.; Prakapenka, V. B.; Kubo, A.; Dera, P.

    2008-12-01

    Magnesium oxide (MgO, periclase) is among the most widely studied standard materials for testing experimental and theoretical methods of determining elastic properties. Because of its simple structure and geophysical relevance, knowledge of accurate elastic properties of MgO pertains to problems ranging from experimental pressure scales to interpreting Earth's seismic structure. The pressure-volume equation of state (EoS) of single-crystal MgO has been studied in diamond-anvil cells loaded with helium to 118 GPa and in a non-hydrostatic KCl pressure medium to 87 GPa using monochromatic synchrotron X-ray diffraction at GSECARS (Sector 13, APS). A third-order Birch-Murnaghan fit to the non-hydrostatic P-V data (KCl medium) yields typical results for the initial volume, V0=74.698(7)Å3, bulk modulus, KT0=164(1)GPa, and pressure derivative, K'=4.05(4) using the non-hydrostatic ruby pressure gauge of Mao et al. (1978). However, compression of MgO in helium yields V0=74.697(6)Å3, KT0=159.6(6)GPa, and K'=3.74(3) using the quasi-hydrostatic ruby gauge of Mao et al. (1986). In helium, the fitted equation of state of MgO underdetermines the pressure by 8% at 100 GPa when compared with the primary MgO pressure scale of Zha et al. (2000), with KT0=160.2GPa and K'=4.03. The results suggest that either the compression mechanism of MgO changes above 40 GPa (in helium), or the ruby pressure gauge requires adjustment for the softer helium pressure medium. We provide a revised ruby pressure gauge for helium pressure media against the primary MgO pressure scale, which will be useful for future high-pressure crystallographic studies of minerals compressed with helium in the 25-140 GPa range of the lower mantle.

  18. Oxidation behavior of a single-crystal Ni-base superalloy between 900 and 1000 {sup o}C in air

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T., E-mail: liuchunting76@yahoo.com.c [College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061 (China); Ma, J. [College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266061 (China); Sun, X.F. [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2010-02-18

    The oxidation behavior of a single-crystal Ni-base superalloy DD32 was studied in air at 900 and 1000 {sup o}C and analyzed by X-ray diffraction (XRD), scanning electron microscopy, combined with energy-dispersive X-ray spectroscopy (SEM/EDS). At 900 and 1000 {sup o}C, two oxidation steps appear in the oxidation kinetics. The first one is controlled by NiO growth and the second by Al{sub 2}O{sub 3} growth until a continuous Al{sub 2}O{sub 3} layer formed under the previously grown NiO layer after a critical time. The variations in the chemical composition due to segregations, which resulted from the solidification process, led to the formation of different kinds of oxide scale on the dendritic and interdendritic area during oxidation between 900 and 1000 {sup o}C. The scales formed between 900 and 1000 {sup o}C were complicated, and consisted of three layers: an outer columnar NiO layer with a small amount of CoO, an intermediate layer mainly composed of W{sub 20}O{sub 58}, CrTaO{sub 4}, a small amount of spinels NiCr{sub 2}O{sub 4}, NiAl{sub 2}O{sub 4} and CoAl{sub 2}O{sub 4}, an inner continuous layer of {alpha}-Al{sub 2}O{sub 3}.

  19. In situ scanning tunneling microscopy study of the structure of the hydroxylated anodic oxide film formed on Cr(110) single-crystal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Zuili, D.; Maurice, V.; Marcus, P. [Ecole Nationale Superieure de Chimie de Paris (France)

    1999-09-16

    The structure of hydroxylated oxide films (passive films) formed on Cr(110) in 0.5 M H{sub 2}SO{sub 4} at +0.35, +0.55, and +0.75 V/SHE has been investigated by in situ scanning tunneling microscopy (STM). Cathodic reduction pretreatments at {minus}0.54, {minus}0.64, and {minus}0.74 V/SHE destroy the well-defined topography of the single-crystal electrode and they have been excluded from the passivation procedure. Two different passive film structures have been observed, depending on the potential and time of passivation. At low potential (+0.35 V/SHE), the passive film, consisting mostly of chromium hydroxide, has a noncrystalline and granular structure whose roughness suggests local variations of thickness of ca. {+-} 0.5 nm. A similar structure is observed at higher potential (+0.55 V/SHE), but only for a short polarization time. For longer polarization at 0.55 V/SHE, and at higher potentials (+0.75 V/SHE), a crystalline structure is formed; the higher the potential, the faster the crystallization. It corresponds to the growth of a chromium oxide layer in the passive film. This chromium oxide layer is (0001) oriented. A structural model of the passive film is proposed, with termination of this oxide layer by a monolayer of hydroxyl groups or of chromium hydroxide in (1 {times} 1) epitaxy with the underlying oxide, and with surface steps resulting from the emergence of stacking faults of the Cr{sup 3+} planes in the oxide layer. Energy band models of the electronic structure of the semiconductive passive films show that the tunneling mechanism of the STM imaging involves empty electronic states located in the band gap of the passive film. The growth of the oxide layer in the passive film is governed by a combined reaction of dehydration of chromium hydroxide and oxidation of chromium: Cr(OH){sub 3} (film) + Cr (metal) {yields} Cr{sub 2}O{sub 3} (film) + 3 H{sup +} + 3 e{sup {minus}}.

  20. Tuning crystal phase of NiSx through electro-oxidized nickel foam: A novel route for preparing efficient electrocatalysts for oxygen evolution reaction

    Science.gov (United States)

    Li, Xiao; Shang, Xiao; Rao, Yi; Dong, Bin; Han, Guan-Qun; Hu, Wen-Hui; Liu, Yan-Ru; Yan, Kai-Li; Chi, Jing-Qi; Chai, Yong-Ming; Liu, Chen-Guang

    2017-02-01

    A facile solvothermal sulfurization using electro-oxidized nickel foam (NF(Ox)) as support has been applied to prepare NiSx/NF(Ox) electrocatalyst with highly efficient activity for oxygen evolution reaction (OER). XRD patterns confirm the composition of NiSx/NF(Ox): two kinds of crystal phase including β-NiS and Ni3S2. While using bare NF as support under identical conditions, only Ni3S2 phase can be detected. SEM images reveal two kinds of morphologies of NiSx/NF(Ox) including pyramids structure of β-NiS and nanorod-like structure of Ni3S2, which implies the tuning effect of electro-pretreatment of NF on the selective preparation of NiSx crystal phase. It can be speculated that Ni(OH)2 layer derived from electro-oxidized NF is responsible for the growth of β-NiS while metallic Ni is transformed into Ni2S3 during sulfurization. Electrochemical measurements for OER indicate the enhanced electrocatalytic activity of NiSx/NF(Ox) with a small overpotential of 72 mV to reach 10 mA cm-2 compared with Ni3S2/NF, which may be ascribed to the improved electron-transfer kinetics relating to the unique atomic configurations and crystalline structures of β-NiS. The electro-oxidation pretreatment of nickel foam provides a simple and convenient method by tuning different NiSx crystal phases for preparing excellent OER eletrocatalysts.

  1. From polymer to monomer: cleavage and rearrangement of Si-O-Si bonds after oxidation yielded an ordered cyclic crystallized structure.

    Science.gov (United States)

    Zuo, Yujing; Gou, Zhiming; Cao, Jinfeng; Yang, Zhou; Lu, Haifeng; Feng, Shengyu

    2015-07-27

    Polymerization reactions are very common in the chemical industry, however, the reaction in which monomers are obtained from polymers is rarely invesitgated. This work reveals for the first time that oxone can break the Si-O-Si bond and induce further rearrangement to yield an ordered cyclic structure. The oxidation of P1, which is obtained by reaction of 2,2'-1,2-ethanediylbis(oxy)bis(ethanethiol) (DBOET) with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane (MM(Vi)), with oxone yielded cyclic crystallized sulfone-siloxane dimer (P1-ox) after unexpected cleavage and rearrangement of the Si-O-Si bond.

  2. The comparison of calculated transition probabilities with luminescence characteristics of erbium(III) in fluoride glasses and in the mixed yttrium-zirconium oxide crystal

    Science.gov (United States)

    Reisfeld, R.; Katz, G.; Jacoboni, C.; De Pape, R.; Drexhage, M. G.; Brown, R. N.; Jørgensen, C. K.

    1983-07-01

    Fluorozirconate glasses containing 2 mole% ErF 3 were prepared by melting the binary fluorides with ammonium bifluoride under an atmosphere of carbon tetrachloride and argon at 850°C. Absorption spectra of these glasses were obtained and the Judd-Ofelt parameters were calculated. Emission spectra and lifetimes of erbium in fluorozirconate glass, in lead-gallium-zinc fluoride glass, and in yttrium-zirconium oxide crystal were measured and compared with the theoretical calculations. Laser emission lines in these materials are deduced from these measurements. It is suggested that materials doped with erbium may serve as light sources for fiber optic waveguides made from the undoped materials.

  3. Four-wave mixing based widely tunable wavelength conversion using 1-m dispersion-shifted bismuth-oxide photonic crystal fiber.

    Science.gov (United States)

    Chow, K K; Kikuchi, K; Nagashima, T; Hasegawa, T; Ohara, S; Sugimoto, N

    2007-11-12

    We demonstrate widely tunable wavelength conversion based on four-wave mixing using a dispersion-shifted bismuth-oxide photonic crystal fiber (Bi-PCF). A 1-meter-long Bi-PCF is used as the nonlinear medium for wavelength conversion of a 10 Gb/s non-return-to-zero (NRZ) signal. A 3- dB working range of the converted signal over 35 nm is obtained with around 1-dB power penalty in the bit-error-rate measurements.

  4. Behavior of Aqueous Electrolytes in Steam Cycles - The Final Report on the Solubility and Volatility of copper(I) and Copper(II) Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, Donald [ORNL; Benezeth, Pascale [Laboratoire des Mecanismes et Transferts en Geologie, Toulouse, France; Simonson, J Michael {Mike} [ORNL

    2004-05-01

    Measurements were completed on the solubility of cupric and cuprous oxides in liquid water and steam at controlled pH conditions from 25 to 400 C (77 to 752 F). The results of this study have been combined with those reported from this laboratory in two previous EPRI reports to provide a complete description of the solubility of these oxides and the speciation of copper dissolved in liquid water and steam as a function of oxidation state, temperature, pH, and in the case of steam, pressure. These constitute the first set of reliable data for cuprous oxide solubility over this range of conditions. For the more intensively studied CuO case, agreement was found between our results and those of previous studies of its solubility in steam, whereas only partial agreement was evident for its solubility in liquid water. For both oxides this disagreement often amounted to orders of magnitude. The solubility of cuprous oxide is somewhat lower than that of CuO at ambient conditions, except as very high pH. However, by 350 C (662 F), Cu{sub 2}O is the more soluble phase. At 100 C (212 F) and above, the logarithm of the solubility of both phases decreases linearly with increasing pH to a minimum value then sharply increases linearly with pH. In other words, above 100 C the solubility of both oxides become highly pH dependent. In fact at constant pH during startup, very high copper concentrations can be reached in the boiler water, more than an order of magnitude above those at ambient or operating temperatures. The enhancing effect of added ammonia on the solubility of both oxides is most significant at low temperatures and is much greater for cuprous oxide. Consequently, the mobility of copper is affected significantly under AVT startup conditions. The oxidation of copper metal and presumably cuprous oxide by addition of air-saturated makeup water can lead to much higher copper concentrations than equilibrium with cupric oxide would allow, but the presence of both copper metal

  5. Technology for Obtaining Large Size Complex Oxide Crystals for Experiments on Muon-Electron Conversion Registration in High Energy Physics

    Directory of Open Access Journals (Sweden)

    Gerasymov, Ya.

    2014-11-01

    Full Text Available Technological approaches for qualitative large size scintillation crystals growing based on rare-earth silicates are proposed. A method of iridium crucibles charging using eutectic phase instead of a oxyorthosilicate was developed.

  6. Purification of molybdenum oxide, growth and characterization of medium size zinc molybdate crystals for the LUMINEU program

    Directory of Open Access Journals (Sweden)

    Shlegel V.N.

    2014-01-01

    Full Text Available The LUMINEU program aims at performing a pilot experiment on neutrinoless double beta decay of 100Mo using radiopure ZnMoO4 crystals operated as scintillating bolometers. Growth of high quality radiopure crystals is a complex task, since there are no commercially available molybdenum compounds with the required levels of purity and radioactive contamination. This paper discusses approaches to purify molybdenum and synthesize compound for high quality radiopure ZnMoO4 crystal growth. A combination of a double sublimation (with addition of zinc molybdate with subsequent recrystallization in aqueous solutions (using zinc molybdate as a collector was used. Zinc molybdate crystals up to 1.5 kg were grown by the low-thermal-gradient Czochralski technique, their optical, luminescent, diamagnetic, thermal and bolometric properties were tested.

  7. Purification of molybdenum oxide, growth and characterization of medium size zinc molybdate crystals for the LUMINEU program

    CERN Document Server

    Shlegel, V N; Boiko, R S; Chapellier, M; Chernyak, D M; Coron, N; Danevich, F A; Decourt, R; Degoda, V Ya; Devoyon, L; Drillien, A; Dumoulin, L; Enss, C; Fleischmann, A; Gastaldo, L; Giuliani, A; Gros, M; Herve, S; Ivanov, I M; Kobychev, V V; Kogut, Ya P; Koskas, F; Loidl, M; Magnier, P; Makarov, E P; Mancuso, M; de Marcillac, P; Marnieros, S; Marrache-Kikuchi, C; Nasonov, S G; Navick, X F; Nones, C; Olivieri, E; Paul, B; Penichot, Y; Pessina, G; Plantevin, O; Poda, D V; Redon, T; Rodrigues, M; Strazzer, O; Tenconi, M; Torres, L; Tretyak, V I; Vasiliev, Ya V; Velazquez, M; Viraphong, O; Zhdankov, V N

    2013-01-01

    The LUMINEU program aims at performing a pilot experiment on neutrinoless double beta decay of 100Mo using radiopure ZnMoO4 crystals operated as scintillating bolometers. Growth of high quality radiopure crystals is a complex task, since there are no commercially available molybdenum compounds with the required levels of purity and radioactive contamination. This paper discusses approaches to purify molybdenum and synthesize compound for high quality radiopure ZnMoO4 crystal growth. A combination of a double sublimation (with addition of zinc molybdate) with subsequent recrystallization in aqueous solutions (using zinc molybdate as a collector) was used. Zinc molybdate crystals up to 1.5 kg were grown by the low-thermal-gradient Czochralski technique, their optical, luminescent, diamagnetic, thermal and bolometric properties were tested.

  8. A Gas Cell Based on Hollow-Core Photonic Crystal Fiber (PCF and Its Application for the Detection of Greenhouse Gas (GHG: Nitrous Oxide (N2O

    Directory of Open Access Journals (Sweden)

    Jonas K. Valiunas

    2016-01-01

    Full Text Available The authors report the detection of nitrous oxide gas using intracavity fiber laser absorption spectroscopy. A gas cell based on a hollow-core photonic crystal fiber was constructed and used inside a fiber ring laser cavity as an intracavity gas cell. The fiber laser in the 1.55 μm band was developed using a polarization-maintaining erbium-doped fiber as the gain medium. The wavelength of the laser was selected by a fiber Bragg grating (FBG, and it matches one of the absorption lines of the gas under investigation. The laser wavelength contained multilongitudinal modes, which increases the sensitivity of the detection system. N2O gas has overtones of the fundamental absorption bands and rovibrational transitions in the 1.55 μm band. The system was operated at room temperature and was capable of detecting nitrous oxide gas at sub-ppmv concentration level.

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

    Directory of Open Access Journals (Sweden)

    Jack N. Blandy

    2015-04-01

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

  10. Crystal Structure,Safety Performance and Density-Functional Theoretical Investigation of 2,6-Diamino-3,5-dinitropyrazine-1-oxide(LLM-105)

    Institute of Scientific and Technical Information of China (English)

    MA Hai-Xia; SONG Ji-Rong; ZHAO Feng-Qi; GAO Hong-Xu; HU Rong-Zu

    2008-01-01

    The single crystal of 2,6-diamino-3,5-dinitropyrazine-l-oxide(LLM-105)suitable for X-ray measurement was obtained by recrystallization from DMSO and water mixed solvent at room temperature.The crystal structure is monoclinic with space group P2(1)/n.The bulk state of LLM-105 was also studied using density functional theory of Dmol3 code.Density of state(DOS)calculations show that C-N bond is the trigger bond of LLM-105 during thermolysis;the heat of formation(HOF)for LLM-105 was evaluated by designing an isodesmic reaction.The detonation velocity,(D)and detonation pressure(P)were estimated by using the well known Kamlet-Jacobs equa-tion,based on the crystal density and HOE The calculation on bond dissociation energy suggests that the C-NO2 bond should be the trigger bond during the pyrolysis initiation process.The specific heat capacity(Cp)of the title compound was determined with a continuous Cp mode mircocalorimeter.Using the relationship between Cp and T and the thermal decomposition parameters,the time of the thermal decomposition from initialization to thermal ex-plosion(adiabatic time-to-explosion)was obtained.

  11. Preparation, crystallization and X-ray diffraction analysis to 1.5 Å resolution of rat cysteine dioxygenase, a mononuclear iron enzyme responsible for cysteine thiol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, Chad R. [Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853-8001 (United States); Hao, Quan [MacCHESS at the Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY 14853-8001 (United States); Stipanuk, Martha H., E-mail: mhs6@cornell.edu [Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853-8001 (United States)

    2005-11-01

    Recombinant rat cysteine dioxygenase (CDO) has been expressed, purified and crystallized and X-ray diffraction data have been collected to 1.5 Å resolution. Cysteine dioxygenase (CDO; EC 1.13.11.20) is an ∼23 kDa non-heme iron metalloenzyme that is responsible for the oxidation of cysteine by O{sub 2}, yielding cysteinesulfinate. CDO catalyzes the first step in the conversion of cysteine to taurine, as well as the first step in the catabolism of cysteine to pyruvate plus sulfate. Recombinant rat CDO was heterologously expressed, purified and crystallized. The protein was expressed as a fusion protein bearing a polyhistidine tag to facilitate purification, a thioredoxin tag to improve solubility and a factor Xa cleavage site to permit removal of the entire N-terminus, leaving only the 200 amino acids inherent to the native protein. A multi-step purification scheme was used to achieve >95% purity of CDO. The optimal CDO crystals diffracted to 1.5 Å resolution and belonged to space group P4{sub 3}2{sub 1}2 or P4{sub 1}2{sub 1}2, with unit-cell parameters a = b = 57.55, c = 123.06 Å, α = β = γ = 90°. CDO shows little homology to any other proteins; therefore, the structure of the enzyme will be determined by ab initio phasing using a selenomethionyl derivative.

  12. SPHERULITIC STRUCTURE AND MORPHOLOGY OF POLY(ETHYLENE SUCCINATE)/POLY(ETHYLENE OXIDE) (PES/PEO) BLENDS WITH ONE-STEP CRYSTALLIZATION

    Institute of Scientific and Technical Information of China (English)

    Jie-ping Liu; Shuan-gai He; Xiao-ping Qiao

    2008-01-01

    The spherlitic structure and morphology development of poly(ethylene succinate)/poly(ethylene oxide) (PES/PEO) blends with one-step crystallization behavior were observed by means of polarizing optical microscope.It was found that the pure PES spherulite in which the adequate quantity of PEO melt existed in the interlamellar regions,and the blending spherulite formed by both PES and PEO lamellae could form simultaneously.When the two types of spherulites contacted with each other the front of the blending spherulite could penetrate into the pure PES spherulite to grow continually.This penetration growth behavior was also observed when the mini-crystal particles of the PES component were formed at lower crystallization temperatures.The kinetics analysis showed that the penetration growth rate was faster than that in the original melt.It was evidenced that the increasing of growth rate and the formation of new growth site should be the typical characteristics of interpenetrated growth in binary crystalline polymer blends.

  13. Solvent effect on the crystal morphology of 2,6-diamino-3,5-dinitropyridine-1-oxide: a molecular dynamics simulation study.

    Science.gov (United States)

    Shi, Wenyan; Xia, Mingzhu; Lei, Wu; Wang, Fengyun

    2014-05-01

    The attachment energy (AE) calculations were performed to predict the growth morphology of 2,6-diamino-3,5-dinitropyridine-1-oxide (ANPyO) in vacuum. The molecular dynamics (MD) method was applied to simulate the interaction of trifluoroacetic acid solvent with the habit faces and the corrected AE model was adopted to predict the growth habit of ANPyO in the solvent. The results indicate that the growth morphology of ANPyO in vacuum is dominated by (110), (100), (10-1) and (11-2) faces. The corrected AE energies change in the order of (110)>(10-1)>(11-2)>(100), which causes the crystal morphology to become very close to a flake in trifluoroacetic acid solvent and accords well with the results obtained from experiments. The radial distribution function analysis shows that the solvent molecules adsorb on the ANPyO faces mainly via the solvent-crystal face interactions of hydrogen bonds, Coulomb and Van der Waals forces. In addition to the above results, the analysis of diffusion coefficient of trifluoroacetic acid molecules on the crystal growth faces shows that the growth habit is also affected by the diffusion capacity of trifluoroacetic acid molecules. These suggestions may be useful for the formulation design of ANPyO.

  14. Synthesis, crystal structure and magnetic properties of new indium rhenium and scandium rhenium oxides, In 6ReO 12 and Sc 6ReO 12

    Science.gov (United States)

    Mikhailova, D.; Ehrenberg, H.; Fuess, H.

    2006-12-01

    The new complex indium rhenium and scandium rhenium oxides, In 6ReO 12 and Sc 6ReO 12, have been synthesized as single phases in sealed silica tubes and by high-pressure high-temperature syntheses, and their crystal structures have been determined by single crystal X-ray diffraction.The compounds crystallize in a rhombohedral structure related to the distorted fluorite structure like Ln 6ReO 12 for some rare earth elements, S. G.: R-3, Z=3, aH= 9.248(2) Å, cH=8.720(2) Å for Sc 6ReO 12 and aH=9.492(1) Å, cH=8.933(1) Å for In 6ReO 12. A maximum in magnetization is observed for Sc 6ReO 12 at T( Mmax)=1.89(2) K, whereas ferromagnetic ordering is found for In 6ReO 12 by a pronounced increase in the temperature dependence of magnetization at TC=7.5(5) K. The magnetic moment per rhenium ion in In 6ReO 12 and Sc 6ReO 12 is 0.84(1) and 0.65(1) μB, respectively, derived from the paramagnetic regions.

  15. Preparation, crystal structure, and magnetic studies of Na 3Fe 2Mo 5O 16, a new oxide containing Mo 3O 13 clusters

    Science.gov (United States)

    Bramnik, K. G.; Muessig, E.; Ehrenberg, H.

    2003-11-01

    The complex oxide Na 3Fe 2Mo 5O 16 has been synthesized, and its crystal structure was determined by single-crystal X-ray diffraction (space group (SG) P-3 m1; a=5.7366(6) Å, c=22.038(3) Å; Z=2). The compound can be considered as a new structure type containing Mo 3O 13 cluster units, which can be derived from the Na 2In 2Mo 5O 16 structure model by doubling of the cell along the c-axis. Na 3Fe 2Mo 5O 16 crystallizes in centrosymmetric SG ( P-3 m1) and the positions of the sodium atoms are fully occupied in contrast to the proposed Na 2In 2Mo 5O 16 model SG ( P3 m1). Magnetic properties of Na 3Fe 2Mo 5O 16 were studied by superconducting quantum interference device measurements, revealing antiferromagnetic ordering below Tχmax=10(1) K. Thermal stability in air was investigated by in situ high-temperature X-ray powder diffraction. Structural relationships to Na 2In 2Mo 5O 16 and NaFe(MoO 4) 2 are discussed.

  16. X-rays diffraction on a new chromium oxide single-crystal thin film prepared by molecular beam epitaxy

    NARCIS (Netherlands)

    Du, X. S.; Hak, S.; Hibma, T.; Rogojanu, O. C.; Struth, B.

    2006-01-01

    Chromium oxide films were prepared on MgO substrates by molecular beam epitaxy. The crystalline structure of the films was characterized by X-ray diffraction (XRD) with conventional as well as synchrotron X-ray sources. The theta-2 theta spectra showed that the film was a new chromium oxide epitaxia

  17. X-rays diffraction on a new chromium oxide single-crystal thin film prepared by molecular beam epitaxy

    NARCIS (Netherlands)

    Du, X. S.; Hak, S.; Hibma, T.; Rogojanu, O. C.; Struth, B.

    2006-01-01

    Chromium oxide films were prepared on MgO substrates by molecular beam epitaxy. The crystalline structure of the films was characterized by X-ray diffraction (XRD) with conventional as well as synchrotron X-ray sources. The theta-2 theta spectra showed that the film was a new chromium oxide

  18. Development of high-efficiency solar cells on copper indium selenide single crystals (cadmium sulfide, zinc oxide)

    Energy Technology Data Exchange (ETDEWEB)

    Yip, Lap Sum

    1996-12-31

    Photovoltaic cells with a ZnO/CdS/CuInSe{sub 2} structure were fabricated on bulk CuInSe{sub 2} substrates. Conversion efficiencies of more than or near 10 per cent were obtained on cells with an active area and without the use of antireflection coating. Copper indium selenide single crystals can be used as absorbers in thin film solar cells. In this study, the single crystals were grown by a horizontal Bridgman method. An annealing of the CuInSe{sub 2} substrate before the CdS deposition was found to be essential in obtaining high photovoltaic performance.

  19. Recent progress in oxide scintillation crystals development by low-thermal gradient Czochralski technique for particle physics experiments

    Science.gov (United States)

    Shlegel, V. N.; Borovlev, Yu. A.; Grigoriev, D. N.; Grigorieva, V. D.; Danevich, F. A.; Ivannikova, N. V.; Postupaeva, A. G.; Vasiliev, Ya. V.

    2017-08-01

    Modern particle physics experiments call for high performance scintillation detectors with unique properties: radiation-resistant in high energy and astrophysics, highly radiopure, containing certain elements or enriched isotopes in astroparticle physics. The low-thermal gradient Czochralski (LTG CZ) crystal growth technique provides excellent quality large volume radiopure crystal scintillators. Absence of thermoelastic stress in the crystal and overheating of the melt in the LTG CZ method is particularly significant in production of crystalline materials with strong thermal anisotropic properties and low mechanical strength, with a very high yield of crystalline boules and low losses of initial charge, crucially important in production of crystal scintillators from enriched isotopes for double beta decay experiments. Here we discuss progress in development of the well known scintillators (Bi4Ge3O12 (BGO), CdWO4, ZnWO4, CaMoO4, PbMoO4), as well as R&D of new materials (ZnMoO4, Li2MoO4, Na2Mo2O7) for the next generation experiments in particle physics.

  20. Enhanced performance of light-controlled conductive switching in hybrid cuprous oxide/reduced graphene oxide (Cusub>2sub>O/rGO) nanocomposites.

    Science.gov (United States)

    Wei, Jing; Zang, Zhigang; Zhang, Yubo; Wang, Ming; Du, Jihe; Tang, Xiaosheng

    2017-03-01

    A significant enhancement of photoresponse from the light-controlled conductive switching based on Cusub>2sub>O/rGO nanocomposites was experimentally demonstrated. Cusub>2sub>O/rGO nanocomposites were synthesized via a facile wet-reduced method. The crystalline structure, morphologies, and photoluminescence of the Cusub>2sub>O/rGO nanocomposites were characterized and analyzed. The fabricated conductive switching was measured under the irradiation of a continuous laser. When the laser was turned on and off alternately, the photoconductive switching obviously displayed a state conversion between "on" and "off" reversibly. Furthermore, the typical current-voltage (I-V) and current-time (I-t) curves exhibited a relatively high switching ratio (Isub>onsub>/Isub>offsub>) of 3.25 and a fast response time of 0.45 s. The excellent "on-off" characteristics of the device show promising applications in memory storage and logic circuits.

  1. Synthesis of alpha-aluminum oxide and hafnium-doped beta-nickel aluminide coatings on single crystal nickel-based superalloy by chemical vapor deposition

    Science.gov (United States)

    He, Limin

    Thermal barrier coatings (TBCs) are widely used for air-cooled turbine components in advanced aircraft engines and power generation systems. The dominant failure mode observed in TBCs is progressive fracture of the metal-oxide interface upon oxidation and thermal cycling. Two potential coating methods for improving TBC performance were studied: (1) preparing a high-quality alpha-Al 2O3 coating layer on the surface of a single crystal Ni-based superalloy (Rene N5) to extend the oxidative stability of the interface and (2) doping beta-NiAl bond coating with a small amount of Hf to improve the adhesion of thermally grown oxide (TGO) at the interface. In the first coating method, a novel chemical vapor deposition (CVD) procedure was developed using AlCl3, CO2 and H 2 as precursors. A critical part of this procedure was a short-time pre-oxidation step (1 min) with CO2 and H2 in the CVD chamber, prior to introducing the AlCl3, vapor. Without this pre-oxidation step, extensive whisker formation was observed on the alloy surface. Characterization results showed that the pre-oxidation step resulted in the formation of a continuous oxide layer (˜50 nm) on the alloy surface. The outer part of this layer (˜20 nm) appeared to contain mixed oxides whereas the inner part (˜30 nm) consisted of alpha-Al2O3 as a dominant major phase and theta-Al2O3 as a minor phase. It appeared that the preferential nucleation of beta-Al2O3 in the pre-oxidized layer was promoted by: (1) rapid heating (˜10 sec) of the alloy surface to the temperature region, where alpha-Al 2O3 was expected to nucleate instead of metastable Al 2O3 phases, (2) the low oxygen pressure environment of the pre-oxidation step which kept the rate of oxidation low, and (3) contamination of the CVD chamber with HfCl4. It appeared that the role of HfCl 4 was to enhance the preferential nucleation of alpha-Al2O 3 in the pre-oxidized layer. In our second coating method, we utilized the dynamic versatility of CVD as an avenue

  2. Effect of oxide nanoparticles on structural properties of multiwalled carbon nanotubes

    Science.gov (United States)

    Dhall, Shivani; Jaggi, Neena

    2016-03-01

    A simple chemical precipitation route is reported to partially decorate mutliwalled carbon nanotubes (MWCNTs) with oxide nanoparticles in the present study. X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopy (SEM) are used to investigate the structural properties of MWCNTs composite with nickel, cuprous, zinc and tin oxides nanoparticles. Raman analysis confirms that, ZnO nanoparticles attached nanotubes show more ordering of graphene layers as compared to the others because of uniform dispersion of nanoparticles. It is investigated that, adopted route proved helpful to improve the structural properties of the nanotubes.

  3. Fundamental Studies on Confinement Effects in Ionic Conduction and Inversion Layers in 2-D Single Crystal Free Standing Oxide Membranes

    Science.gov (United States)

    2014-02-14

    Scientific Progress Please see below Technology Transfer Number of graduating undergraduates who achieved a 3.5 GPA to 4.0 (4.0 max scale): Number of...2-dimensional free standing membrane with correlated oxides may also lead to new insights into mesoscopic electronic phenomena. Vanadium oxide ( VO2 ...well as for potential applications in switching devices. While studies have been conducted on thin films, hybrid layers of VO2 supported on other

  4. Investigation of photoelectrochemical oxidation of Fe{sup 2+} ions on porous nanocrystalline TiO{sub 2} electrodes using electrochemical quartz crystal microbalance

    Energy Technology Data Exchange (ETDEWEB)

    Si Shihui; Huang Kelong; Wang Xiaoguang; Huang Mingzhi; Chen Hanfang

    2002-12-20

    The photoelectrochemical oxidation of Fe{sup 2+} ions on porous nanocrystalline TiO{sub 2} electrodes was investigated using in situ electrochemical quartz crystal microbalance (QCM). It was found that the adsorption of Fe{sup 2+} ions at the surface of TiO{sub 2} electrodes strongly depended on the pH of the solution, and that the saturated amount of adsorbed Fe{sup 2+} ions was approximately 4.4 ions nm{sup -2} at pH 4. The protons produced in photochemical reactions could cause the release of adsorbed Fe{sup 2+} ions from TiO{sub 2} surface, therefore, the frequency of QCM increased at the initial stage of illumination, during which the direct oxidation of adsorbed Fe{sup 2+} ions by photogenerated holes was dominant. When the frequency decreased, the major reaction was the photoelectrochemical deposition of Fe{sub 2}O{sub 3} from the bulk solution via a hydroxyl radical-mediated oxidation pathway, whose efficiency depended on the Fe{sup 2+} ion concentration.

  5. Influences of MCrAlY coatings on oxidation resistance of single crystal superalloy DD98M and their inter-diffusion behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Long [School of Materials and Metallurgy, Northeastern University, Shenyang 110819 (China); Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Xin, Li, E-mail: xli@imr.ac.cn [Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, Xinyue; Wang, Xiaolan; Wei, Hua; Zhu, Shenglong; Wang, Fuhui [Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2015-11-15

    Oxidation and interdiffusion behaviors of Ni-based single crystal superalloy DD98M with nominal compositions Ni–5.0Co–6.0Cr–6.3Al–6.0W–2.0Mo–6.0Ta–1.0Ti (in wt.%) and two types of MCrAlY coatings at 1000 °C and 1050 °C were investigated. Complex oxides formed on the surface of DD98M alloy when oxidized at 1000 °C and 1050 °C, which stratified, cracked and spalled. The faceted-like AlN and the particle-like and strip-like TiN formed in the alloy. The application of the NiCrAlY and NiCoCrAlYHfSi coatings greatly improved the oxidation resistance of DD98M alloy. After 500 h oxidation, α-Al{sub 2}O{sub 3} was still the dominate phase in the oxide scales formed on the coated specimens. The adhesion of the oxide scale on the NiCoCrAlYHfSi coating was much better than that on the NiCrAlY coating. Interdiffusion occurred between the coatings and the substrate, which led to the formation of the IDZ and SRZ. The IDZ of the NiCrAlY coated specimen was composed of γ phase and Al- and Ta-rich γ′ phase. The γ′ phase in the IDZ accommodated most of the inward diffusing aluminum, so the SRZ formation was suppressed when oxidized at 1050 °C. However the formation of SRZ with μ-TCP still occurred when oxidized at 1000 °C probably due to the low solubility and slow diffusion rate of the alloying elements at lower temperature. The IDZ of the NiCoCrAlYHfSi coated specimen was a single γ phase. A large amount of μ-TCP precipitated in the SRZ of the NiCoCrAlYHfSi coated specimen when oxidized at 1000 °C and 1050 °C. It can be concluded coating composition has a significant effect on the development of the IDZ and SRZ. Thermal exposure temperature also has influences on the formation of the SRZ. The mechanism of SRZ formation and TCP precipitation are discussed. - Graphical abstract: The TEM micrograph of the IDZ and SRZ of the NiCoCrAlYHfSi-coated specimen oxidized at 1050 °C for 100 h and the respective diffraction patterns of the needle-like and the

  6. High-pressure synthesis and crystal structure of a new strontium ruthenium oxide: Sr{sub 2}Ru{sub 3}O{sub 10}

    Energy Technology Data Exchange (ETDEWEB)

    Renard, C.; Daviero-Minaud, S.; Abraham, F. [Univ. des Sciences et Technologies de Lille, Villeneuve d`Ascq (France). Lab. de Cristallochimie et Physicochimie du Solide

    1999-03-01

    The new ternary oxide Sr{sup 2}Ru{sub 3}O{sub 10} has been prepared under hydrothermal conditions (480--650 C, 1800--2100 bars) and characterized by X-ray single crystal diffraction data. The structure was refined in C2/m space group with a = 10.985(3) {angstrom}, b = 5.635(1) {angstrom}, c = 6.452(6) {angstrom}, and {beta} = 105.3(4){degree}. The structure refinement converged to R = 0.032 and R{sub w} = 0.042. The ruthenium atoms with a mean oxidation number of 5.33 occupy two sorts of octahedral sites. The first form infinite rutile-like chains parallel to the b axis, while the second link these chains together to form layers parallel to (100) plane. The average Ru-O bond distance in the two types of octahedra does not allow assignment of an integral oxidation number to individual Ru ions. The Sr{sup 2+} cations are located in the interlayer space ensuring the stacking cohesion. The Sr{sub 2}Ru{sub 3}O{sub 10} structure can also be described by the stacking of SrO{sub 5} layers. The same stoichiometry is encountered in the barium fluorides Ba{sub 2}M{sub 3}F{sub 10} (M = Ni, Cu, or Zn) but the stacking sequence is based on BaF{sub 3} and BaF{sub 7} layers. Sr{sub 2}Ru{sub 3}O{sub 10} is the first example of strontium ruthenium oxide with Ru/Sr ratio higher than one. The Sr/Ru ratio is allowed by the existence of SrO{sub 5} layers, which creates 1.5 octahedral sites per SrO{sub 5} layer.

  7. Synthesis, Crystal Structure, Magnetism, and Optical Properties of Gd 3[SiON 3]O—An Oxonitridosilicate Oxide with Noncondensed SiON 3 Tetrahedra

    Science.gov (United States)

    Höppe, Henning A.; Kotzyba, Gunter; Pöttgen, Rainer; Schnick, Wolfgang

    2002-09-01

    The novel oxonitridosilicate oxide (sion oxide) Gd 3[SiON 3]O was obtained by the reaction of gadolinium metal with its carbonate oxide and silicon diimide in a radiofrequency (r.f.) furnace at a temperature of 1400°C. The crystal structure of Gd 3[SiON 3]O ( I4/ mcm, a=649.1(2) pm, c=1078.8(6) pm, Z=4, R1=0.0411, w R2=0.0769, 405 F2 values, 19 parameters, 123 K) is isotypic with that of Ba 3[SiO 4]O and Cs 3[CoCl 4]Cl. It can be derived from the perovskite structure type by a hierarchical substitution: Ti 4+→O 2-, O 2-→Gd 3+, Ca 2+→[SiON 3] 7- resulting in the formation of large [OGd 6] 16+ octahedra, which are twisted by ξ=16.47(1)° around [001]. The low-temperature single-crystal data investigation led to a crystallographic splitting of the central O atom which could not be resolved at room temperature. The UV-Vis absorption spectra in reflection geometry of the yellow title compound revealed two overlaying broad bands, one peaking at almost the same wavelength as observed in gadolinium oxide (340 nm) and a second red-shifted band at approximately 400 nm indicating a strong influence of nitrogen on the ligand field splitting of the 5 d states of Gd 3+. Temperature-dependent magnetic susceptibility measurements of Gd 3[SiON 3]O show Curie-Weiss behavior from 2 to 300 K with an experimental magnetic moment of 7.68(5) μB/Gd, indicating trivalent gadolinium. There is no evidence for magnetic ordering down to 2 K. According to the paramagnetic Curie temperature of -7(1) K, the exchange between the gadolinium magnetic moments is supposed to be only weak. The vibrational spectroscopic data (IR and Raman) are reported.

  8. Effect of the ion-beam bombardment and annealing temperature on sol-gel derived yttrium aluminum oxide film as liquid crystal alignment layer

    Science.gov (United States)

    Jeong, Hae-Chang; Heo, Gi-Seok; Kim, Eun-Mi; Lee, Ju Hwan; Han, Jeong-Min; Seo, Dae-Shik

    2017-02-01

    We demonstrated a homogeneous liquid-crystal (LC) alignment state on yttrium aluminum oxide (YAlO) films, where the alignment was induced by ion-beam (IB) irradiation. Topographical analysis was performed by atomic force microscopy as a function of annealing temperature. Higher annealing temperatures yielded a smoother surface, accompanied by reduced light scattering. Transparency in the visible region increased on the surface fabricated at higher annealing temperatures. LC alignment mechanism was determined by X-ray diffraction (XRD) analysis. Moreover, IB-irradiated YAlO films annealed at temperatures greater than 200 °C exhibited good thermal stability and low capacitance-voltage hysteresis. The IB-irradiated YAlO films are suitable as alternative alignment layers in advanced LC display applications.

  9. Combined Charge Carrier Transport and Photoelectrochemical Characterization of BiVO4 Single Crystals: Intrinsic Behavior of a Complex Metal Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Rettie, Alexander J.; Lee, Heung Chan; Marshall, Luke G.; Lin, Jung-Fu; Capen, Cigdem; Lindemuth, Jeffrey; McCloy, John S.; Zhou, Jianshi; Bard, Allen J.; Mullins, C. Buddie

    2013-07-08

    ABSTRACT: Bismuth vanadate (BiVO4) is a promising photoelectrode material for the oxidation of water, but fundamental studies of this material are lacking. To address this, we report electrical and photoelectrochemical (PEC) properties of BiVO4 single crystals (undoped, 0.6% Mo and 0.3% W:BiVO4) grown using the floating zone technique. We demonstrate that a small polaron hopping conduction mechanism dominates from 250-400 K, transitioning to a variable range hopping mechanism at lower temperatures. An anisotropy ratio of ~3 was observed along the c-axis, attributed to the layered structure of BiVO4. Measurements of the AC field Hall effect yielded an electron mobility of ~0.2 cm2 V-1 s-1 for Mo and W:BiVO4 at 300 K. By application of the Gärtner model, a hole diffusion length of ~140 nm was estimated. As a result of low carrier mobility, attempts to measure the DC Hall effect were unsuccessful. Analyses of the Raman spectra showed that Mo and W substituted for V and acted as donor impurities. Mott-Schottky analysis of electrodes with the (001) face exposed yielded a flat band potential of 0.03-0.08 V vs. RHE, while incident photon conversion efficiency tests showed that the dark coloration of the doped single crystals did not result in additional photocurrent. Comparison of these intrinsic properties to other metal oxides for PEC applications gives valuable insight into this material as a photoanode.

  10. Combined charge carrier transport and photoelectrochemical characterization of BiVO4 single crystals: intrinsic behavior of a complex metal oxide.

    Science.gov (United States)

    Rettie, Alexander J E; Lee, Heung Chan; Marshall, Luke G; Lin, Jung-Fu; Capan, Cigdem; Lindemuth, Jeffrey; McCloy, John S; Zhou, Jianshi; Bard, Allen J; Mullins, C Buddie

    2013-07-31

    Bismuth vanadate (BiVO4) is a promising photoelectrode material for the oxidation of water, but fundamental studies of this material are lacking. To address this, we report electrical and photoelectrochemical (PEC) properties of BiVO4 single crystals (undoped, 0.6% Mo, and 0.3% W:BiVO4) grown using the floating zone technique. We demonstrate that a small polaron hopping conduction mechanism dominates from 250 to 400 K, undergoing a transition to a variable-range hopping mechanism at lower temperatures. An anisotropy ratio of ~3 was observed along the c axis, attributed to the layered structure of BiVO4. Measurements of the ac field Hall effect yielded an electron mobility of ~0.2 cm(2) V(-1) s(-1) for Mo and W:BiVO4 at 300 K. By application of the Gärtner model, a hole diffusion length of ~100 nm was estimated. As a result of low carrier mobility, attempts to measure the dc Hall effect were unsuccessful. Analyses of the Raman spectra showed that Mo and W substituted for V and acted as donor impurities. Mott-Schottky analysis of electrodes with the (001) face exposed yielded a flat band potential of 0.03-0.08 V versus the reversible H2 electrode, while incident photon conversion efficiency tests showed that the dark coloration of the doped single crystals did not result in additional photocurrent. Comparison of these intrinsic properties to those of other metal oxides for PEC applications gives valuable insight into this material as a photoanode.

  11. High-pressure synthesis, crystal structure, and unusual valence state of novel perovskite oxide CaCu3Rh4O12.

    Science.gov (United States)

    Yamada, Ikuya; Ochi, Mikiko; Mizumaki, Masaichiro; Hariki, Atsushi; Uozumi, Takayuki; Takahashi, Ryoji; Irifune, Tetsuo

    2014-07-21

    A novel perovskite oxide, CaCu3Rh4O12, has been synthesized under high-pressure and high-temperature conditions (15 GPa and 1273 K). Rietveld refinement of synchrotron X-ray powder diffraction data indicates that this compound crystallizes in a cubic AA'3B4O12-type perovskite structure. Synchrotron X-ray absorption and photoemission spectroscopy measurements reveal that the Cu and Rh valences are nearly trivalent. The spectroscopic analysis based on calculations suggests that the appropriate ionic model of this compound is Ca(2+)Cu(∼2.8+)3Rh(∼3.4+)4O12, as opposed to the conventional Ca(2+)Cu(2+)3Rh(4+)4O12. The uncommon valence state of this compound is attributed to the relative energy levels of the Cu 3d and Rh 4d orbitals, in which the large crystal-field splitting energy of the Rh 4d orbitals is substantial.

  12. High mobility In{sub 2}O{sub 3}:H transparent conductive oxides prepared by atomic layer deposition and solid phase crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Macco, B.; Wu, Y.; Vanhemel, D. [Department of Applied Physics, Eindhoven University of Technology (Netherlands); Kessels, W.M.M. [Department of Applied Physics, Eindhoven University of Technology (Netherlands); Solliance Solar Research, Eindhoven (Netherlands)

    2014-12-01

    The preparation of high-quality In{sub 2}O{sub 3}:H, as transparent conductive oxide (TCO), is demonstrated at low temperatures. Amorphous In{sub 2}O{sub 3}:H films were deposited by atomic layer deposition at 100 C, after which they underwent solid phase crystallization by a short anneal at 200 C. TEM analysis has shown that this approach can yield films with a lateral grain size of a few hundred nm, resulting in electron mobility values as high as 138 cm{sup 2}/V s at a device-relevant carrier density of 1.8 x 10{sup 20} cm{sup -3}. Due to the extremely high electron mobility, the crystallized films simultaneously exhibit a very low resistivity (0.27 mΩ cm) and a negligible free carrier absorption. In conjunction with the low temperature processing, this renders these films ideal candidates for front TCO layers in for example silicon heterojunction solar cells and other sensitive optoelectronic applications. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Preparation, Crystallization and X-ray Diffraction Analysis to 1.5 A Resolution of Rat Cysteine Dioxygenase, a Mononuclear Iron Enzyme Responsible for Cysteine Thiol Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Simmons,C.; Hao, Q.; Stipanuk, M.

    2005-01-01

    Cysteine dioxygenase (CDO; EC 1.13.11.20) is an {approx}23 kDa non-heme iron metalloenzyme that is responsible for the oxidation of cysteine by O2, yielding cysteinesulfinate. CDO catalyzes the first step in the conversion of cysteine to taurine, as well as the first step in the catabolism of cysteine to pyruvate plus sulfate. Recombinant rat CDO was heterologously expressed, purified and crystallized. The protein was expressed as a fusion protein bearing a polyhistidine tag to facilitate purification, a thioredoxin tag to improve solubility and a factor Xa cleavage site to permit removal of the entire N-terminus, leaving only the 200 amino acids inherent to the native protein. A multi-step purification scheme was used to achieve >95% purity of CDO. The optimal CDO crystals diffracted to 1.5 Angstroms resolution and belonged to space group P4{sub 3}2{sub 1}2 or P4{sub 1}2{sub 1}2, with unit-cell parameters a = b = 57.55, c = 123.06 Angstrom, {alpha} = {beta} = {gamma} = 90. CDO shows little homology to any other proteins; therefore, the structure of the enzyme will be determined by ab initio phasing using a selenomethionyl derivative.

  14. Solid-state transition metal chemistry with quinolin-4-yl-methyl-[N-(n-butyl)amino]-diphenylphosphine oxide (4-qmape): Crystal structure of the 4-qmape ligand

    Science.gov (United States)

    Żurowska, Bogumiła; Brzuszkiewicz, Anna; Boduszek, Bogdan

    2012-11-01

    A series of three perchlorate coordination compounds of bioactive diethyl quinolin-4-yl-methyl(N-butylamino)diphenylphosphine oxide (4-qmape) ligand, with the following stoichiometries [M(2-qmape)2](ClO4)2 Mdbnd Cu and Ni and [Co(2-qmape)2](ClO4)2, were obtained and studied. Stoichiometry and stereochemistry of the compounds was confirmed by spectroscopic and magnetic studies as well as by elemental analyses. In particular, the crystal structure of the free ligand was determined. The 4-qmape ligand has a potential capacity to coordinate to metal ions by following atoms: phosphoryl oxygen, amino nitrogen and quinolyl nitrogen. In studied compounds, 4-qmape adopts the didentate N,O-coordination mode, bonding metal centers through the phosphoryl oxygen and amino nitrogen. Quinoline nitrogen atom does not participate in coordination. The all complexes are monomeric with tetrahedral environment of metal ions. Magnetic studies (1.8-300 K) indicate existence of a very weak exchange coupling between metal centers in crystal lattice.

  15. Crystal structure of quinone-dependent alcohol dehydrogenase from Pseudogluconobacter saccharoketogenes. A versatile dehydrogenase oxidizing alcohols and carbohydrates

    NARCIS (Netherlands)

    Rozeboom, Henriette J.; Yu, Shukun; Mikkelsen, Rene; Nikolaev, Igor; Mulder, Harm J.; Dijkstra, Bauke W.

    2015-01-01

    The quinone-dependent alcohol dehydrogenase (PQQ-ADH, E.C. 1.1.5.2) from the Gram-negative bacterium Pseudogluconobacter saccharoketogenes IFO 14464 oxidizes primary alcohols (e.g. ethanol, butanol), secondary alcohols (monosaccharides), as well as aldehydes, polysaccharides, and cyclodextrins. The

  16. Developing porous ceramics on the base of zirconia oxide with thin and permeable pores by crystallization of organic additive method

    Science.gov (United States)

    Kamyshnaya, K. S.; Khabas, T. A.

    2016-11-01

    In this paper porous ceramics on the base of ZrO2 nanopowders and micropowders has been developed by freeze-casting method. A zirconia/carbamide slurry was frozen in mold and dehydrated in CaCl2 at room temperature. This simple process enabled the formation of porous ceramics with highly aligned pores as a replica of the carbamide crystals. The samples showed higher porosity of 47.9%. In addition, these materials could be used as membrane for air cleaning.

  17. Final Report - Effects of High Spinel and Chromium Oxide Crystal Contents on Simulated HLW Vitrification in DM100 Melter Tests, VSL-09R1520-1, Rev. 0, dated 6/22/09

    Energy Technology Data Exchange (ETDEWEB)

    Kruger, Albert A.; Matlack, K. S.; Kot, W.; Pegg, I. L.; Chaudhuri, M.; Lutze, W.

    2013-11-13

    The principal objective of the work was to evaluate the effects of spinel and chromium oxide particles on WTP HLW melter operations and potential impacts on melter life. This was accomplished through a combination of crucible-scale tests, settling and rheological tests, and tests on the DM100 melter system. Crucible testing was designed to develop and identify HLW glass compositions with high waste loadings that exhibit formation of crystalline spinel and/or chromium oxide phases up to relatively high crystal contents (i.e., > 1 vol%). Characterization of crystal settling and the effects on melt rheology was performed on the HLW glass formulations. Appropriate candidate HLW glass formulations were selected, based on characterization results, to support subsequent melter tests. In the present work, crucible melts were formulated that exhibit up to about 4.4 vol% crystallization.

  18. Oxide-cladding aluminum nitride photonic crystal slab: Design and investigation of material dispersion and fabrication induced disorder

    Energy Technology Data Exchange (ETDEWEB)

    Melo, E. G., E-mail: emerdemelo@usp.br; Alvarado, M. A.; Carreño, M. N. P.; Alayo, M. I. [Electronic Systems Engineering Department, University of São Paulo, CEP 05508-010 São Paulo, SP (Brazil); Carvalho, D. O. [UNESP - São Paulo State University, CEP 13874-149 São João da Boa Vista, SP (Brazil); Ferlauto, A. S. [Department of Physics, Federal University of Minas Gerais, CEP 31270-901 Belo Horizonte, MG (Brazil)

    2016-01-14

    Photonic crystal slabs with a lower-index material surrounding the core layer are an attractive choice to circumvent the drawbacks in the fabrication of membranes suspended in air. In this work we propose a photonic crystal (PhC) slab structure composed of a triangular pattern of air holes in a multilayer thin film of aluminum nitride embedded in silicon dioxide layers designed for operating around 450 nm wavelengths. We show the design of an ideal structure and analyze the effects of material dispersion based on a first-order correction perturbation theory approach using dielectric functions obtained by experimental measurements of the thin film materials. Numerical methods were used to investigate the effects of fabrication induced disorder of typical nanofabrication processes on the bandgap size and spectral response of the proposed device. Deviation in holes radii and positions were introduced in the proposed PhC slab model with a Gaussian distribution profile. Impacts of slope in holes sidewalls that might result from the dry etching of AlN were also evaluated. The results show that for operation at the midgap frequency, slope in holes sidewalls is more critical than displacements in holes sizes and positions.

  19. Phase transformation mechanism in lithium manganese nickel oxide revealed by single-crystal hard X-ray microscopy

    Science.gov (United States)

    Kuppan, Saravanan; Xu, Yahong; Liu, Yijin; Chen, Guoying

    2017-02-01

    Understanding the reaction pathway and kinetics of solid-state phase transformation is critical in designing advanced electrode materials with better performance and stability. Despite the first-order phase transition with a large lattice mismatch between the involved phases, spinel LiMn1.5Ni0.5O4 is capable of fast rate even at large particle size, presenting an enigma yet to be understood. The present study uses advanced two-dimensional and three-dimensional nano-tomography on a series of well-formed LixMn1.5Ni0.5O4 (0<=x<=1) crystals to visualize the mesoscale phase distribution, as a function of Li content at the sub-particle level. Inhomogeneity along with the coexistence of Li-rich and Li-poor phases are broadly observed on partially delithiated crystals, providing direct evidence for a concurrent nucleation and growth process instead of a shrinking-core or a particle-by-particle process. Superior kinetics of (100) facets at the vertices of truncated octahedral particles promote preferential delithiation, whereas the observation of strain-induced cracking suggests mechanical degradation in the material.

  20. An electrochemical quartz crystal impedance study on anti-human immunoglobulin G immobilization in the polymer grown during dopamine oxidation at an Au electrode.

    Science.gov (United States)

    He, Hua; Xie, Qingji; Yao, Shouzhuo

    2005-09-15

    The polymeric film grown during dopamine oxidation at an Au electrode was studied as a novel matrix for immobilizing anti-human immunoglobulin G (IgG) via the electrochemical quartz crystal impedance analysis (EQCIA) method. The growth of the polymeric films at Au electrodes during dopamine oxidation in neutral phosphate buffer (pH 7.4) and the immobilization of anti-human IgG into the polymeric films during their growth have been traced at real time. Lysozyme control experiments suggested that anti-human IgG was electrostatically incorporated into the polymeric film. Also, the porosity of the polymeric films has been discussed by measuring the "wet" and "dry" frequency shifts. Compared with a polypyrrole film immobilized with anti-human IgG, the proposed matrix possessed a larger amount of specific binding sites for human IgG by subsequent immunoreaction tests. The association constant of the anti-human IgG immunoreaction was obtained with satisfactory results.

  1. A thermolysis approach to simultaneously achieve crystal phase- and shape-control of ternary M-Fe-O metal oxide nanoparticles.

    Science.gov (United States)

    Huang, Chih-Chia; Chang, Chich-Neng; Yeh, Chen-Sheng

    2011-10-05

    Significant studies have achieved beautiful control in particle size, while the shape- and phase-control synthesis of nanoparticles remains an open challenge. In this study, we have developed a generalized methodology to selectively prepare either NaCl-type (reduced form) or spinel-type ferrite (oxidized form) M-Fe-O (M = Mn, Co) crystallites with high reproducibility. A two-step heating process was able to control formation of two types of crystal phase, either a thermodynamic spinel-type under air or a kinetic-control of NaCl-type (rock salt structure) under Ar in a cubic morphology. On the other hand, the three-step heating procedure in air obtained the spinel-type with a thermodynamic equilibrium octahedral shape exclusively. Either using metal acetates (M(ac)(2)) or metal acetylacetonates (M(acac)(2)) as the starting precursors (M = Mn, Co) can be introduced to prepare NaCl-type (reduced form) or spinel-type ferrite (oxidized form) crystallites with identical experimental parameters, including precursor concentration, reaction temperature, reaction time, and heating rate. The oleic acid molecule, reaction temperature, and heating rate employed in the synthesis were carefully examined and found acting as determined roles behind the reaction processes. Apart from the previous literature reports as shape-directed and/or stabilizing agents, the oleic acid molecule played an additional phase-tuning role.

  2. Study on the crystallization behaviour and thermal stability of glass-ceramics used as solid oxide fuel cell-sealing materials

    Science.gov (United States)

    Gödeke, Dieter; Dahlmann, Ulf

    Glass ceramics are commonly used as sealing materials for planar solid oxide fuel cells (SOFCs). The major requirements of stack and module builders for these materials are the stability of the coefficient of thermal expansion (CTE), excellent bonding (sticking) behaviour and the absence of volatile ingredients, which can lead to changes of the material properties and the sealing ability. SCHOTT Electronic Packaging has developed special glasses and glass-ceramics for various solid oxide fuel cell designs and operating temperatures. The glass compositions are based on the system MgO-Al 2O 3-BaO-SiO 2-B 2O 3. In this study the evaluation of the developed materials was done by high temperature aging tests for up to 1000 h, high temperature XRD-studies and Rietveld calculations, combined with scanning-electron microscope analysis. Samples of these aged samples were chemically analysed by XRD and wet chemical methods. Results show that after thermal aging of the glasses barium silicates accompanied by barium-magnesium silicates are the major crystalline phases of the glasses. The crystal phases remain stable during high temperature aging tests, indicating a low driving force of material change. The experimental results are compared to phase diagrams by phenomenological and thermochemical considerations.

  3. Crystallization and electrical resistivity of Cu{sub 2}O and CuO obtained by thermal oxidation of Cu thin films on SiO{sub 2}/Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    De Los Santos Valladares, L., E-mail: ld301@cam.ac.uk [Cavendish Laboratory, University of Cambridge, J.J Thomson Av., Cambridge CB3 0HE (United Kingdom); Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan); Departamento de Fisica, Universidade Federal de Pernambuco, 50670-901, Recife-Pe (Brazil); Salinas, D. Hurtado [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan); Laboratorio de Ceramicos y Nanomateriales, Facultad de Ciencias Fisicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima (Peru); Dominguez, A. Bustamante [Laboratorio de Ceramicos y Nanomateriales, Facultad de Ciencias Fisicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima (Peru); Najarro, D. Acosta [Instituto de Fisica, Departamento de Materia Condensada, Universidad Nacional Autonoma de Mexico, Ap. Postal 20-364, CP 01000 (Mexico); Khondaker, S.I. [NanoScience Technology Centre and Department of Physics, University of Central Florida, Orlando, FL 32826 (United States); Mitrelias, T.; Barnes, C.H.W. [Cavendish Laboratory, University of Cambridge, J.J Thomson Av., Cambridge CB3 0HE (United Kingdom); Aguiar, J. Albino [Departamento de Fisica, Universidade Federal de Pernambuco, 50670-901, Recife-Pe (Brazil); Majima, Y. [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan); CREST, Japan Science and Technology Agency (JST), 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan)

    2012-08-01

    In this work, we study the crystallization and electrical resistivity of the formed oxides in a Cu/SiO{sub 2}/Si thin film after thermal oxidation by ex-situ annealing at different temperatures up to 1000 Degree-Sign C. Upon increasing the annealing temperature, from the X ray diffractogram the phase evolution Cu {yields} Cu + Cu{sub 2}O {yields} Cu{sub 2}O {yields} Cu{sub 2}O + CuO {yields} CuO was detected. Pure Cu{sub 2}O films are obtained at 200 Degree-Sign C, whereas uniform CuO films without structural surface defects such as terraces, kinks, porosity or cracks are obtained in the temperature range 300-550 Degree-Sign C. In both oxides, crystallization improves with annealing temperature. A resistivity phase diagram, which is obtained from the current-voltage response, is presented here. The resistivity was expected to increase linearly as a function of the annealing temperature due to evolution of oxides. However, anomalous decreases are observed at different temperatures ranges, this may be related to the improvement of the crystallization and crystallite size when the temperature increases. - Highlights: Black-Right-Pointing-Pointer The crystallization and electrical resistivity of oxides in a Cu films are studied. Black-Right-Pointing-Pointer In annealing Cu films, the phase evolution Cu + Cu{sub 2}O {yields} Cu{sub 2}O {yields} Cu{sub 2}O + CuO {yields} CuO occurs. Black-Right-Pointing-Pointer A resistivity phase diagram, obtained from the current-voltage response, is presented. Black-Right-Pointing-Pointer Some decreases in the resistivity may be related to the crystallization.

  4. Function development through microstructure control. Control of crystal axis orientation of zinc oxide and its optical properties; Soshiki seigyo ni yoru kino hatsugen. Sanka aen no haikosei seigyo to kogakuteki kino

    Energy Technology Data Exchange (ETDEWEB)

    Fujitsu, S. [Shonan Institute of Technology, Kanagawa (Japan); Watanabe, Y. [Science University of Tokyo, Tokyo (Japan)

    1998-04-01

    Described herein are light beam deflectors of thin piezoelectric films, and synthesis, photoconductance and nonlinear optical measurement of light-distributing, transparent zinc oxide, viewed from application of zinc oxide to optical purposes. Supersonic waves, when passing through a transparent medium, leaves compressional waves of strain, causing cyclic changes in refractive index. This phenomenon can be used for diffraction of light. A light beam deflector is one of the examples of using this phenomenon applied to a thin piezoelectric film of zinc oxide. The authors have developed a process to synthesize transparent, polycrystalline zinc oxide of high C-axis orientation. A seed of sintered zinc oxide is placed at the center of an electrical oven, and a substrate in the temperature-gradient zone. The seed evaporates, when heated to around 1200degC, to leave the zinc oxide crystal grains on the substrate, which grow preferentially in the C-axis direction at around 300{mu}m/h. Zinc oxide is known as a compound of anisotropy in properties by crystal orientation, and shows piezoelectric and photoconducting properties. 8 refs., 7 figs.

  5. The Crystal Structure of the Ivy delta4-16:0-ACP Desaturase Reveals Structural Details of the Oxidized Active Site and Potential Determinants of Regioselectivity

    Energy Technology Data Exchange (ETDEWEB)

    Guy,J.; Whittle, E.; Kumaran, D.; Lindqvist, Y.; Shanklin, J.

    2007-01-01

    The multifunctional acyl-acyl carrier protein (ACP) desaturase from Hedera helix (English ivy) catalyzes the {Delta}{sup 4} desaturation of 16:0-ACP and the{Delta}{sup 9} desaturation of 18:0-ACP and further desaturates{Delta}{sup 9}-16:1 or {Delta}{sup 9}-18:1 to the corresponding {Delta}{sup 4,9} dienes. The crystal structure of the enzyme has been solved to 1.95{angstrom} resolution, and both the iron-iron distance of 3.2{angstrom} and the presence of a {mu}-oxo bridge reveal this to be the only reported structure of a desaturase in the oxidized FeIII-FeIII form. Significant differences are seen between the oxidized active site and the reduced active site of the Ricinus communis (castor) desaturase; His{sup 227} coordination to Fe2 is lost, and the side chain of Glu{sup 224}, which bridges the two iron ions in the reduced structure, does not interact with either iron. Although carboxylate shifts have been observed on oxidation of other diiron proteins, this is the first example of the residue moving beyond the coordination range of both iron ions. Comparison of the ivy and castor structures reveal surface amino acids close to the annulus of the substrate-binding cavity and others lining the lower portion of the cavity that are potential determinants of their distinct substrate specificities. We propose a hypothesis that differences in side chain packing explains the apparent paradox that several residues lining the lower portion of the cavity in the ivy desaturase are bulkier than their equivalents in the castor enzyme despite the necessity for the ivy enzyme to accommodate three more carbons beyond the diiron site.

  6. Room temperature inorganic polycondensation of oxide (Cu{sub 2}O and ZnO) nanoparticles and thin films preparation by the dip-coating technique

    Energy Technology Data Exchange (ETDEWEB)

    Salek, G.; Tenailleau, C., E-mail: tenailleau@chimie.ups-tlse.fr; Dufour, P.; Guillemet-Fritsch, S.

    2015-08-31

    Oxide thin solid films were prepared by dip-coating into colloidal dispersions of oxide nanoparticles stabilized at room temperature without the use of chelating or complex organic dispersing agents. Crystalline oxide nanoparticles were obtained by inorganic polycondensation and characterized by X-ray diffraction and field emission gun scanning electron microscopy. Water and ethanol synthesis and solution stabilization of oxide nanoparticle method was optimized to prepare two different structural and compositional materials, namely Cu{sub 2}O and ZnO. The influence of hydrodynamic parameters over the particle shape and size is discussed. Spherical and rod shape nanoparticles were formed for Cu{sub 2}O and ZnO, respectively. Isoelectric point values of 7.5 and 8.2 were determined for cuprous and zinc oxides, respectively, after zeta potential measurements. A shear thinning and thixotropic behavior was observed in both colloidal sols after peptization at pH ~ 6 with dilute nitric acid. Every colloidal dispersion stabilized in a low cost and environmentally friendly azeotrope solution composed of 96 vol.% of ethanol with water was used for the thin film preparation by the dip-coating technique. Optical properties of the light absorber cuprous oxide and transparent zinc oxide thin solid films were characterized by means of transmittance and reflectance measurements (300–1100 nm). - Highlights: • Room temperature inorganic polycondensation of crystalline oxides • Water and ethanol synthesis and solution stabilization of oxide nanoparticles • Low cost method for thin solid film preparation.

  7. Enhanced Cherenkov phase matching terahertz wave generation via a magnesium oxide doped lithium niobate ridged waveguide crystal

    Science.gov (United States)

    Takeya, K.; Minami, T.; Okano, H.; Tripathi, S. R.; Kawase, K.

    2017-01-01

    When combined with a nonlinear waveguide crystal, Cherenkov phase matching allows for highly effective generation of high power and broadband terahertz (THz) waves. Using a ridged Lithium Niobate (LiNbO3) waveguide coupled with a specially designed silicon lens, we successfully generated THz waves with intensity of approximately three orders of magnitude stronger than those from conventional photoconductive antenna. The broadband spectrum was from 0.1 THz to 7 THz with a maximum dynamic range of 80 dB. The temporal shape of time domain pulse is a regular single cycle which could be used for high depth resolution time of flight tomography. The generated THz wave can also be easily monitored by compact room-temperature THz camera, enabling us to determine the spatial characteristics of the THz propagation.

  8. Enhanced Cherenkov phase matching terahertz wave generation via a magnesium oxide doped lithium niobate ridged waveguide crystal

    Directory of Open Access Journals (Sweden)

    K. Takeya

    2017-01-01

    Full Text Available When combined with a nonlinear waveguide crystal, Cherenkov phase matching allows for highly effective generation of high power and broadband terahertz (THz waves. Using a ridged Lithium Niobate (LiNbO3 waveguide coupled with a specially designed silicon lens, we successfully generated THz waves with intensity of approximately three orders of magnitude stronger than those from conventional photoconductive antenna. The broadband spectrum was from 0.1 THz to 7 THz with a maximum dynamic range of 80 dB. The temporal shape of time domain pulse is a regular single cycle which could be used for high depth resolution time of flight tomography. The generated THz wave can also be easily monitored by compact room-temperature THz camera, enabling us to determine the spatial characteristics of the THz propagation.

  9. Persistent Microvascular Obstruction After Myocardial Infarction Culminates in the Confluence of Ferric Iron Oxide Crystals, Proinflammatory Burden, and Adverse Remodeling.

    Science.gov (United States)

    Kali, Avinash; Cokic, Ivan; Tang, Richard; Dohnalkova, Alice; Kovarik, Libor; Yang, Hsin-Jung; Kumar, Andreas; Prato, Frank S; Wood, John C; Underhill, David; Marbán, Eduardo; Dharmakumar, Rohan

    2016-11-01

    Emerging evidence indicates that persistent microvascular obstruction (PMO) is more predictive of major adverse cardiovascular events than myocardial infarct (MI) size. But it remains unclear how PMO, a phenomenon limited to the acute/subacute period of MI, drives adverse remodeling in chronic MI setting. We hypothesized that PMO resolves into chronic iron crystals within MI territories, which in turn are proinflammatory and favor adverse remodeling post-MI. Canines (n=40) were studied with cardiac magnetic resonance imaging to characterize the spatiotemporal relationships among PMO, iron deposition, infarct resorption, and left ventricular remodeling between day 7 (acute) and week 8 (chronic) post-MI. Histology was used to assess iron deposition and to examine relationships between iron content with macrophage infiltration, proinflammatory cytokine synthesis, and matrix metalloproteinase activation. Atomic resolution transmission electron microscopy was used to determine iron crystallinity, and energy-dispersive X-ray spectroscopy was used to identify the chemical composition of the iron composite. PMO with or without reperfusion hemorrhage led to chronic iron deposition, and the extent of this deposition was strongly related to PMO volume (r>0.8). Iron deposits were found within macrophages as aggregates of nanocrystals (≈2.5 nm diameter) in the ferric state. Extent of iron deposits was strongly correlated with proinflammatory burden, collagen-degrading enzyme activity, infarct resorption, and adverse structural remodeling (r>0.5). Crystallized iron deposition from PMO is directly related to proinflammatory burden, infarct resorption, and adverse left ventricular remodeling in the chronic phase of MI in canines. Therapeutic strategies to combat adverse remodeling could potentially benefit from taking into account the chronic iron-driven inflammatory process. © 2016 American Heart Association, Inc.

  10. Crystal and Magnetic Structures of the Oxide Sulfides CaCoSO and BaCoSO.

    Science.gov (United States)

    Salter, Edward J T; Blandy, Jack N; Clarke, Simon J

    2016-02-15

    CaCoSO, synthesized from CaO, Co, and S at 900 °C, is isostructural with CaZnSO and CaFeSO. The structure is non-centrosymmetric by virtue of the arrangement of the vertex-sharing CoS3O tetrahedra which are linked by their sulfide vertices to form layers. The crystal structure adopts space group P63mc (No. 186), and the lattice parameters are a = 3.7524(9) Å and c = 11.138(3) Å at room temperature with two formula units in the unit cell. The compound is highly insulating, and powder neutron diffraction measurements reveal long-range antiferromagnetic order with a propagation vector k = (1/3, 1/3, 1/2). The magnetic scattering from a powder sample can be modeled starting from a 120° arrangement of Co(2+) spin vectors in the triangular planes and then applying a canting out of the planes which can be modeled in the magnetic space group C(c)c (space group 9.40 in the Belov, Neronova, and Smirnova (BNS) scheme) with Co(2+) moments of 2.72(5) μ(B). The antiferromagnetic structure of the recently reported compound BaCoSO, which has a very different crystal structure from CaCoSO, is also described, and this magnetic structure and the magnitude of the ordered moment (2.75(2) μ(B)) are found by experiment to be similar to those predicted computationally.

  11. Nano Copper Oxide-Modified Carbon Cloth as Cathode for a Two-Chamber Microbial Fuel Cell

    Science.gov (United States)

    Dong, Feng; Zhang, Peng; Li, Kexun; Liu, Xianhua; Zhang, Pingping

    2016-01-01

    In this work, Cu2O nanoparticles were deposited on a carbon cloth cathode using a facile electrochemical method. The morphology of the modified cathode, which was characterized by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) tests, showed that the porosity and specific surface area of the cathode improved with longer deposition times. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) results showed that cupric oxide and cuprous oxide coexisted on the carbon cloth, which improved the electrochemical activity of cathode. The cathode with a deposition time of 100 s showed the best performance, with a power density twice that of bare carbon cloth. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) results revealed that moderate deposition of nano copper oxide on carbon cloth could dramatically reduce the charge transfer resistance, which contributed to the enhanced electrochemical performance. The mediation mechanism of copper oxide nanocatalyst was illustrated by the fact that the recycled conversion between cupric oxide and cuprous oxide accelerated the electron transfer efficiency on the cathode.

  12. Nano Copper Oxide-Modified Carbon Cloth as Cathode for a Two-Chamber Microbial Fuel Cell

    Directory of Open Access Journals (Sweden)

    Feng Dong

    2016-12-01

    Full Text Available In this work, Cu2O nanoparticles were deposited on a carbon cloth cathode using a facile electrochemical method. The morphology of the modified cathode, which was characterized by scanning electron microscopy (SEM and Brunauer-Emmett-Teller (BET tests, showed that the porosity and specific surface area of the cathode improved with longer deposition times. X-ray photoelectron spectroscopy (XPS and cyclic voltammetry (CV results showed that cupric oxide and cuprous oxide coexisted on the carbon cloth, which improved the electrochemical activity of cathode. The cathode with a deposition time of 100 s showed the best performance, with a power density twice that of bare carbon cloth. Linear sweep voltammetry (LSV and electrochemical impedance spectroscopy (EIS results revealed that moderate deposition of nano copper oxide on carbon cloth could dramatically reduce the charge transfer resistance, which contributed to the enhanced electrochemical performance. The mediation mechanism of copper oxide nanocatalyst was illustrated by the fact that the recycled conversion between cupric oxide and cuprous oxide accelerated the electron transfer efficiency on the cathode.

  13. Oxidation Mechanism of Copper Selenide

    Science.gov (United States)

    Taskinen, Pekka; Patana, Sonja; Kobylin, Petri; Latostenmaa, Petri

    2014-09-01

    The oxidation mechanism of copper selenide was investigated at deselenization temperatures of copper refining anode slimes. The isothermal roasting of synthetic, massive copper selenide in flowing oxygen and oxygen - 20% sulfur dioxide mixtures at 450-550 °C indicate that in both atmospheres the mass of Cu2Se increases as a function of time, due to formation of copper selenite as an intermediate product. Copper selenide oxidises to copper oxides without formation of thick copper selenite scales, and a significant fraction of selenium is vaporized as SeO2(g). The oxidation product scales on Cu2Se are porous which allows transport of atmospheric oxygen to the reaction zone and selenium dioxide vapor to the surrounding gas. Predominance area diagrams of the copper-selenium system, constructed for selenium roasting conditions, indicate that the stable phase of copper in a selenium roaster gas with SO2 is the sulfate CuSO4. The cuprous oxide formed in decomposition of Cu2Se is further sulfated to CuSO4.

  14. Crystal structure of 2-chloro-1,3-bis(2,6-diisopropylphenyl-1,3,2-diazaphospholidine 2-oxide

    Directory of Open Access Journals (Sweden)

    Alex J. Veinot

    2017-05-01

    Full Text Available The title compound, C26H38ClN2OP, was synthesized by reacting phosphoryl chloride with N,N′-bis(2,6-diisopropylphenylethane-1,2-diamine in the presence of N-methylmorpholine which acted as an auxilliary base to quench the HCl released as a by-product. The resultant N-heterocyclic phosphine five-membered ring adopts a half-chair conformation and features a tetracoordinate P atom ligated by the chelating diamine [P—N = 1.6348 (14 and 1.6192 (14 Å], one double-bonded O atom [P1—O1 = 1.4652 (12 Å] and one Cl atom [P1—Cl1 = 2.0592 (7 Å]. The sterically hindered 2,6-diisopropylphenyl (Dipp groups twist away from the central heterocycle, with torsion angles of −75.66 (19 and 83.39 (19° for the P—N—Car—Car links. A number of intramolecular C—H...N, C—H...O and C—H...Cl close contacts occur. In the crystal, molecules are linked by C—H...O hydrogen bonds to generate [010] chains. C—H...π interactions are also observed.

  15. Calculation of optical and K pre-edge absorption spectra for ferrous iron of distorted sites in oxide crystals

    Science.gov (United States)

    Vercamer, Vincent; Hunault, Myrtille O. J. Y.; Lelong, Gérald; Haverkort, Maurits W.; Calas, Georges; Arai, Yusuke; Hijiya, Hiroyuki; Paulatto, Lorenzo; Brouder, Christian; Arrio, Marie-Anne; Juhin, Amélie

    2016-12-01

    Advanced semiempirical calculations have been performed to compute simultaneously optical absorption and K pre-edge x-ray absorption spectra of Fe2 + in four distinct site symmetries found in minerals. The four symmetries, i.e., a distorted octahedron, a distorted tetrahedron, a square planar site, and a trigonal bipyramidal site, are representative of the Fe2 + sites found in crystals and glasses. A particular attention has been paid to the definition of the p -d hybridization Hamiltonian which occurs for noncentrosymmetric symmetries in order to account for electric dipole transitions. For the different sites under study, an excellent agreement between calculations and experiments was found for both optical and x-ray absorption spectra, in particular in terms of relative intensities and energy positions of electronic transitions. To our knowledge, these are the first calculations of optical absorption spectra on Fe2 + placed in such diverse site symmetries, including centrosymmetric sites. The proposed theoretical model should help to interpret the features of both the optical absorption and the K pre-edge absorption spectra of 3 d transition metal ions and to go beyond the usual fingerprint interpretation.

  16. Electrocatalytic activity of Cu2O nanocubes-based electrode for glucose oxidation

    Indian Academy of Sciences (India)

    Sathiyanathan Felix; Pratap Kollu; Bala P C Raghupathy; Soon Kwan Jeong; Andrews Nirmala Grace

    2014-01-01

    A direct electrocatalytic activity of glucose oxidation on cuprous oxide modified glassy carbon electrode is reported. Cu2O nanocubes were synthesized by a simple wet chemical route in the absence of surfactants. Purity, shape and morphology of Cu2O are characterized by XRD, SEM, XPS and DRS-UV. The Cu2O nanocubes-modified glassy carbon electrode (GCE) exhibited high electrocatalytic activity towards glucose oxidation compared with bare GCE electrode. At an applied potential of +0.60V, the Cu2O electrode presented a high sensitivity of 121.7 A/mM. A linear response was obtained from 0 to 500 M, a response time less than 5 s and a detection limit of 38 M (signal/noise=3). The Cu2O nanocubes-modified electrode was stable towards interfering molecules like uric acid (UA), ascorbic acid (AA) and dopamine (DA). In short, a facile chemical preparation process of cuprous oxide nanocubes, and the fabricated modified electrode allow highly sensitive, selective, and fast amperometric sensing of glucose, which is promising for the future development of non-enzymatic glucose sensors.

  17. A new approach for crystallization of copper(ii) oxide hollow nanostructures with superior catalytic and magnetic response

    Science.gov (United States)

    Singh, Inderjeet; Landfester, Katharina; Chandra, Amreesh; Muñoz-Espí, Rafael

    2015-11-01

    We report the synthesis of copper(ii) oxide hollow nanostructures at ambient pressure and close to room temperature by applying the soft templating effect provided by the confinement of droplets in miniemulsion systems. Particle growth can be explained by considering a mechanism that involves both diffusion and reaction control. The catalytic reduction of p-nitrophenol in aqueous media is used as a model reaction to prove the catalytic activity of the materials: the synthesized hollow structures show nearly 100 times higher rate constants than solid CuO microspheres. The kinetic behavior and the order of the reduction reaction change due to the increase of the surface area of the hollow structures. The synthesis also leads to modification of physical properties such as magnetism.We report the synthesis of copper(ii) oxide hollow nanostructures at ambient pressure and close to room temperature by applying the soft templating effect provided by the confinement of droplets in miniemulsion systems. Particle growth can be explained by considering a mechanism that involves both diffusion and reaction control. The catalytic reduction of p-nitrophenol in aqueous media is used as a model reaction to prove the catalytic activity of the materials: the synthesized hollow structures show nearly 100 times higher rate constants than solid CuO microspheres. The kinetic behavior and the order of the reduction reaction change due to the increase of the surface area of the hollow structures. The synthesis also leads to modification of physical properties such as magnetism. Electronic supplementary information (ESI) available: Associated structural and morphological analysis, XPS characterization, BET surface area, catalytic measurements, recycle tests of the catalyst, and magnetic characterizations. See DOI: 10.1039/c5nr05579b

  18. Synthesis,Crystal Structural and Electrical Conductivity Properties of Fe-Doped Zinc Oxide Powders at High Temperatures

    Institute of Scientific and Technical Information of China (English)

    Hakan Colak; Orhan Trkoglu

    2012-01-01

    The synthesis,crystal structure and electrical conductivity properties of Fe-doped ZnO powders(in the range of 0.25-15 mol%) were reported in this paper.I-phase samples,which were indexed as single phase with a hexagonal(wurtzite) structure in the Fe-doped ZnO binary system,were determined by X-ray diffraction(XRD).The solubility limit of Fe in the ZnO lattice is 3 mol% at 950℃.The above mixed phase was observed.And the impurity phase was determined as the cubic-ZnFe 2 O 4 phase when compared with standard XRD data using the PDF program.This study focused on single I-phase ZnO samples which were synthesized at 950℃ because the limit of the solubility range is the widest at this temperature.The lattice parameters a and c of the I-phase decreased with Fe-doping concentration.The morphology of the I-phase samples was analyzed with a scanning electron microscope.The grain size of the I-phase samples increased with heat treatment and doping concentration.The electrical conductivity of the pure ZnO and single I-phase samples was investigated using the four-probe dc method at 100-950℃ in air atmosphere.The electrical conductivity values of pure ZnO,0.25 and 3 mol% Fe-doped ZnO samples at 100℃ were 2×10-6,1.7×10-3 and 6.3×10-4 S.cm-1,and at 950℃ they were 3.4,8.5 and 4 S.cm-1,respectively.

  19. HISTORICAL MEMOIR: The play of light in crystals

    Science.gov (United States)

    Zakharchenya, Boris Petrovitch

    2008-11-01

    crystal cells, and such an exciton may be called a mega-atom. How can we observe this mega-atom in a crystal? One might think we could do so simply by observing the hydrogen-like exciton spectrum. By virtue of the well-known behaviour of a hydrogen-like atom in a Coulomb potential well, the exciton is expected to show a series of lines, getting characteristically closer and closer towards the continuous absorption boundary where the motion of electrons and holes has become free. In this region the exciton is ionized. So a series of narrow lines of the spectrum of the exciton (mega-atom in a crystal) must be observed at the absorption edge, which corresponds to electron transfer into the conduction band by light. This series should be similar, for instance, to the Balmer series of the hydrogen atom---well known from school textbooks. One might think all this is simple. But nobody had ever observed anything like it. The semiconductor spectra looked very trivial---exactly the same as the spectrum of a light filter, transparent on the long wavelength side (low-energy light quanta) and having rather intense absorption in the short-wavelength region. It is simple: at first the energy of photons is insufficient for electron transfer into the conduction band, but eventually their energy becomes high enough for such a transfer and the crystal absorbs light strongly. But why, when observing an absorption edge and the photo-current associated with it, did nobody see the hydrogen-like lines of the exciton? The answer is simple and cannot be expressed better than in Pushkin's words: 'We all are lazy and incurious.' As soon as Evgeny Feodorovich Gross, of the Physico-Technical Institute of Leningrad, took a thin plate of cuprous oxide (a ruby-coloured semiconductor), cooled it down to liquid nitrogen temperature (-196 °C) and, above all, used a spectral device with great dispersion, he saw at once a series of hydrogen-like exciton lines. Of course, Gross was lucky that it was a

  20. Crystal structure and physical properties of Cr oxide with K2NiF4-type structure

    Science.gov (United States)

    Kao, Ting-Hui; Sakurai, Hiroya; Kolodiazhnyi, Taras; Suzuki, Yutaro; Okabe, Momoko; Asaka, Toru; Fukuda, Koichiro; Okubo, Susumu; Ikeda, Shohei; Hara, Shigeo; Sakurai, Takahiro; Ohta, Hitoshi; Yang, Hung-Duen; National Sun-Yet Sen University Team; National InstituteMaterials Science Team; Nagoya Institute of Technology Collaboration; Kobe University Collaboration

    2015-03-01

    Ruddlesden-Popper (RP) type structure materials have been attracted much attention due to their interesting physical properties including high-Tc superconductivity, charge stripe, itinerant ferromagnetism and so on. In this work we are presenting physical properties of some of the K2NiF4 type structure compounds. YSrCrO4 is first synthesized and found to be a hetto-type K2NiF4 structure. The space group of YSrCrO4 is determined to be orthorhombic Pccn by the electron diffraction and the powder X-ray diffraction. YSrCrO4 shows two-dimensional (2D) spin correlations and a canted antiferromagnetic (AF) ordering. Evidence of AF ordering of the Cr oxides is obtained microscopically from ESR. The dielectric measurements suggest existence of in-gap states, while no magneto-dielectric coupling was observed in the above compounds. National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.

  1. Laser-induced periodic surface structures on zinc oxide crystals upon two-colour femtosecond double-pulse irradiation

    Science.gov (United States)

    Höhm, S.; Rosenfeld, A.; Krüger, J.; Bonse, J.

    2017-03-01

    In order to study the temporally distributed energy deposition in the formation of laser-induced periodic surface structures (LIPSS) on single-crystalline zinc oxide (ZnO), two-colour double-fs-pulse experiments were performed. Parallel or cross-polarised double-pulse sequences at 400 and 800 nm wavelength were generated by a Mach–Zehnder interferometer, exhibiting inter-pulse delays up to a few picoseconds between the sub-ablation 50-fs-pulses. Twenty two-colour double-pulse sequences were collinearly focused by a spherical mirror to the sample surface. The resulting LIPSS periods and areas were analysed by scanning electron microscopy. The delay-dependence of these LIPSS characteristics shows a dissimilar behaviour when compared to the semiconductor silicon, the dielectric fused silica, or the metal titanium. A wavelength-dependent plasmonic mechanism is proposed to explain the delay-dependence of the LIPSS on ZnO when considering multi-photon excitation processes. Our results support the involvement of nonlinear processes for temporally overlapping pulses. These experiments extend previous two-colour studies on the indirect semiconductor silicon towards the direct wide band-gap semiconductor ZnO and further manifest the relevance of the ultrafast energy deposition for LIPSS formation.

  2. Crystal structure of a samarium(III nitrate chain cross-linked by a bis-carbamoylmethylphosphine oxide ligand

    Directory of Open Access Journals (Sweden)

    Julie A. Stoscup

    2014-10-01

    Full Text Available In the title compound poly[aquabis(μ-nitrato-κ4O,O′:O,O′′tetrakis(nitrato-κ2O,O′{μ4-tetraethyl [(ethane-1,2-diylbis(azanediylbis(2-oxoethane-2,1-diyl]diphosphonate-κ2O,O′}disamarium(III], [Sm2(NO36(C14H30N2O8P2(H2O]n, a 12-coordinate SmIII and a nine-coordinate SmIII cation are alternately linked via shared bis-bidentate nitrate anions into a corrugated chain extending parallel to the a axis. The nine-coordinate SmIII atom of this chain is also chelated by a bidentate, yet flexible, carbamoylmethylphoshine oxide (CMPO ligand and bears one water molecule. This water molecule is hydrogen bonded to nitrate groups bonded to the 12-coordinate SmIII cation. The CMPO ligand, which lies about an inversion center, links neighboring chains along the c axis, forming sheets parallel to the ac plane. Hydrogen bonds between the amide NH group and metal-bound nitrate anions are also present in these sheets. The sheets are packed along the b axis through only van der Waals interactions.

  3. Graphene oxide liquid crystals as a versatile and tunable alignment medium for the measurement of residual dipolar couplings in organic solvents.

    Science.gov (United States)

    Lei, Xinxiang; Xu, Zhen; Sun, Han; Wang, Shun; Griesinger, Christian; Peng, Li; Gao, Chao; Tan, Ren X

    2014-08-13

    Residual dipolar couplings (RDCs) have proven to be an invaluable anisotropic NMR parameter for the structural elucidation of complex biopolymers and organic molecules. However, a remaining bottleneck limiting its wider use by organic and natural product chemists is the lack of a range of easily applicable aligning media for diverse organic solvents. In this study, graphene oxide (GO) liquid crystals (LCs) were developed to induce partial orientation of organic molecules to allow RDC measurements. These LCs were determined to be maintainable at very low concentrations (as low as 1 mg/mL, corresponding to quadrupolar (2)H splittings ranging from 2.8 to 30 Hz and maximum (13)C-(1)H dipolar couplings of 20 Hz for camphor in a CH3COCH3/water system) and to be remarkably stable and broadly compatible with aqueous and organic solvents such as dimethyl sulfoxide, CH3COCH3, and CH3CN. Moreover, compared with those for other alignment media, very clean and high-quality NMR spectra were acquired with the GO molecules in solution because of their rigidity and high molecular weight. The developed medium offers a versatile and robust method for RDC measurements that may routinize the RDC-based structure determination of organic molecules.

  4. Synthesis and crystal structures of mercury(II) and cadmium(II) coordination compounds using 4‧-(4-pyridyl)-2,2‧:6‧,2‧-terpyridine ligand and their thermolysis to nanometal oxides

    Science.gov (United States)

    Mehrani, Azadeh; Morsali, Ali

    2014-09-01

    Two new complexes with the ligand 4‧-(4-pyridyl)-2,2‧:6‧,2‧-terpyridine (pyterpy), [Hg(pyterpy)2](ClO4)2 and [Cd(pyterpy)2](ClO4)2ṡH2O, have been synthesized and characterized by elemental analysis, IR spectroscopy and structurally analyzed by X-ray single-crystal diffraction. The single crystal X-ray analysis shows that the coordination number in these complexes is six and the “pyterpy” ligand acts as a tridentate donor. The thermolysis studies show that the calcination of [Cd(pyterpy)2](ClO4)2ṡH2O leads to formation of cadmium oxide nano-particles while the calcination of mercury(II) complex does not form HgO as mercury evaporated before getting oxide.

  5. Ultrasound promoted mild and facile one-pot, three component synthesis of 2H-indazoles by consecutive condensation, CN and NN bond formations catalysed by copper-doped silica cuprous sulphate (CDSCS) as an efficient heterogeneous nano-catalyst.

    Science.gov (United States)

    Soltani Rad, Mohammad Navid

    2017-01-01

    An ultrasonic promoted facile and convenient one-pot three-component procedure for the synthesis of 2H-indazole derivatives using copper-doped silica cuprous sulphate (CDSCS) as a heterogeneous nano-catalyst has been described. In this approach, ultrasonic mediated reaction of different substituted 2-bromobenzaldehydes, structurally diverse primary amines, and tetrabutylammonium azide (TBAA) as an azide source in the presence of CDSCS in DMSO at room temperature furnishes 2H-indazoles in good to excellent yields. Utilizing ultrasonic irradiation techniques provided the dramatic improvements in terms of higher yields and shorter reaction times compared with conventional heating method.

  6. Crystals in crystals

    DEFF Research Database (Denmark)

    Christensen, Claus H.; Schmidt, I.; Carlsson, A.;

    2005-01-01

    A major factor governing the performance of catalytically active particles supported on a zeolite carrier is the degree of dispersion. It is shown that the introduction of noncrystallographic mesopores into zeolite single crystals (silicalite-1, ZSM-5) may increase the degree of particle dispersion...... of the zeolite particles, particularly after thermal treatment. When using mesoporous zeolites, the particles were evenly distributed throughout the mesopore system of the zeolitic support, even after calcination, leading to nanocrystals within mesoporous zeolite single crystals....

  7. Easy oxidative addition of the carbon-halogen bond by dimethylplatinum(II) complexes containing a related series of diimine ligands: Synthesis, spectral characterization and crystal structure

    Science.gov (United States)

    Momeni, Badri Z.; Fathi, Nastaran; Mohagheghi, Arezoo

    2015-01-01

    Dimethylplatinum(II) complexes [PtMe2(NN)] {NN = 4,4‧-Me2bpy (4,4‧-dimethyl-2,2‧-bipyridine); 5,5‧-Me2bpy (5,5‧-dimethyl-2,2‧-bipyridine)} were reacted with alkyl halides (RX = EtI, EtBr) to yield the organoplatinum(IV) complexes [PtMe2RX(NN)]. On the basis of NMR data, the platinum(IV) product of each reaction contains almost exclusively the trans isomer but small traces of the cis isomers are also observed. On the other hand, the reaction of [PtMe2(NN)] {NN = bu2bpy (4,4‧-di-tert-butyl-2,2‧-bipyridine); 4,4‧-Me2bpy; 5,5‧-Me2bpy} with CH2Br2 gave a mixture of cis and trans-[PtMe2(CH2Br)Br(NN)] formed by the oxidative addition of one of the C-Br bonds. The formation of the cis isomer increases in the order of 5,5‧-Me2bpy > bu2bpy > 4,4‧-Me2bpy. The reaction of [PtMe2(NN)] {NN = bpy (2,2‧-bipyridine), phen (1,10-phenanthroline)} with 1,8-dibromooctane or 1,9-dibromononane afforded the mononuclear complexes [PtMe2{(CH2)nBr}Br(NN)] (n = 8-9). The products were fully characterized by elemental analysis, 1H, 13C, HH COSY, HMQC, DEPT and DEPTQ-135 NMR spectroscopy. The crystal structure of [PtMe2EtI(4,4‧-Me2bpy)] reveals that Pt(IV) atom is six-coordinated in a slightly distorted octahedral geometry with the ethyl group trans to iodide.

  8. Enhanced sandwich immunoassay using antibody-functionalized magnetic iron-oxide nanoparticles for extraction and detection of soluble transferrin receptor on a photonic crystal biosensor.

    Science.gov (United States)

    Peterson, Ross D; Chen, Weili; Cunningham, Brian T; Andrade, Juan E

    2015-12-15

    Iron deficiency anemia (IDA) has detrimental effects on individuals and societies worldwide. A standard sandwich assay (SA) for the detection of soluble transferrin receptor (sTfR), a biomarker of IDA, on a photonic crystal (PC) biosensor was established, but it was susceptible to non-specific signals from complex matrixes. In this study, iron-oxide nanoparticles (fAb-IONs) were used as magnetic immuno-probes to bind sTfR and minimize non-specific signals, while enhancing detection on the PC biosensor. This inverse sandwich assay (IA) method completely bound sTfR with low variability (detection in sera (Liquichek™ control sera) on the PC biosensor using two certified ELISAs as reference methods. A linear dose-response curve was elicited at the fAb-IONs concentration in which the theoretical binding ratio (sTfR:fAb-IONs) was calculated to be 0.05) at 14 and 21 μg/mL, respectively. The inherent imprecision of the IA and reference ELISAs was σ(δ)=0.45 µg/mL and the mean biases for Liquichek™ 1, 2 and 3 were 0.18, 0.19 and -0.04 µg/mL, respectively. Whereas the inherent imprecision of the SA and reference ELISAs was σ(δ)=0.52 µg/mL and the biases for Liquichek™ 1, 2 and 3 were 0.66, 0.14 and -0.67 µg/mL, respectively. Thus, unlike the SA, the IA method measures sTfR with the same bias as the reference ELISAs. Combined magnetic separation and detection of nutrition biomarkers on PC biosensors represents a facile method for their accurate and reliable quantification in complex matrixes.

  9. Structure-property relationships in cubic cuprous iodide: A novel view on stability, chemical bonding, and electronic properties

    Science.gov (United States)

    Pishtshev, A.; Karazhanov, S. Zh.

    2017-02-01

    Based on the combination of density functional theory and theory-group methods, we performed systematic modeling of γ-CuI structural design at the atomistic level. Being started from the metallic copper lattice, we treated a crystal assembly as a stepwise iodination process characterized in terms of a sequence of intermediate lattice geometries. These geometries were selected and validated via screening of possible structural transformations. The genesis of chemical bonding was studied for three structural transformations by analyzing the relevant changes in the topology of valence electron densities. We determined structural trends driven by metal-ligand coupling. This allowed us to suggest the improved scenario of chemical bonding in γ-CuI. In particular, the unconventional effect of spatial separation of metallic and covalent interactions was found to be very important with respect to the preferred arrangements of valence electrons in the iodination process. We rigorously showed that useful electronic and optical properties of γ-CuI originate from the combination of two separated bonding patterns—strong covalency established in I-Cu tetrahedral connections and noncovalent interactions of copper cores is caused by the 3d10 closed-shell electron configurations. The other finding of ours is that the self-consistency of the GW calculations is crucial for correctly determining the dynamic electronic correlations in γ-CuI. Detail reinvestigation of the quasi-particle energy structure by means of the self-consistent GW approach allowed us to explain how p-type electrical conductivity can be engineered in the material.

  10. Structure-property relationships in cubic cuprous iodide: A novel view on stability, chemical bonding, and electronic properties.

    Science.gov (United States)

    Pishtshev, A; Karazhanov, S Zh

    2017-02-14

    Based on the combination of density functional theory and theory-group methods, we performed systematic modeling of γ-CuI structural design at the atomistic level. Being started from the metallic copper lattice, we treated a crystal assembly as a stepwise iodination process characterized in terms of a sequence of intermediate lattice geometries. These geometries were selected and validated via screening of possible structural transformations. The genesis of chemical bonding was studied for three structural transformations by analyzing the relevant changes in the topology of valence electron densities. We determined structural trends driven by metal-ligand coupling. This allowed us to suggest the improved scenario of chemical bonding in γ-CuI. In particular, the unconventional effect of spatial separation of metallic and covalent interactions was found to be very important with respect to the preferred arrangements of valence electrons in the iodination process. We rigorously showed that useful electronic and optical properties of γ-CuI originate from the combination of two separated bonding patterns-strong covalency established in I-Cu tetrahedral connections and noncovalent interactions of copper cores is caused by the 3d(10) closed-shell electron configurations. The other finding of ours is that the self-consistency of the GW calculations is crucial for correctly determining the dynamic electronic correlations in γ-CuI. Detail reinvestigation of the quasi-particle energy structure by means of the self-consistent GW approach allowed us to explain how p-type electrical conductivity can be engineered in the material.

  11. Crystal science fundamentals

    OpenAIRE

    Ramachandran, V.; Halfpenny, PJ; Roberts, KJ

    2017-01-01

    The fundamentals of crystal science notably crystallography, crystal chemistry, crystal defects, crystal morphology and the surface chemistry of crystals are introduced with particular emphasis on organic crystals.

  12. Effect of heat-treatment on phase formation and crystallization of sol–gel derived Al2O3, ZrO2–Y2O3, and Ta2O5 oxide coatings

    Directory of Open Access Journals (Sweden)

    Yang-Il Jung

    2015-06-01

    Full Text Available Various oxides of Al2O3, ZrO2–Y2O3, and Ta2O5 were coated on ferritic–martensitic steel for application as an environmental barrier layer. Sol–gel based coating was investigated to form the oxides by varying the coating parameters, such as the concentration of the precursors, the temperature of the curing, cycles of repeated runs, and additional heat-treatment. The obtained coatings revealed nano-sized granular structures. The surface morphologies were rough in alumina and zirconia, but appeared smooth in tantalum oxide. In the case of alumina and tantalum oxide, coated layers were mostly amorphous after pyrolysis at 750 °C. The crystalline phases were obtained after an additional heat-treatment at 950 °C. In the case of zirconia, a desirable oxide phase was formed when the samples were cured at 750 °C during the coating process. In addition to the heat-treatment after the coating, the repeated coatings were effective in crystallizing the coated layers and forming proper oxides.

  13. Antisolvent crystallization approach to construction of CuI superstructures with defined geometries.

    Science.gov (United States)

    Kozhummal, Rajeevan; Yang, Yang; Güder, Firat; Küçükbayrak, Umut M; Zacharias, Margit

    2013-03-26

    A facile high-yield production of cuprous iodide (CuI) superstructures is reported by antisolvent crystallization using acetonitrile/water as a solvent/antisolvent couple under ambient conditions. In the presence of trace water, the metastable water droplets act as templates to induce the precipitation of hollow spherical CuI superstructures consisting of orderly aligned building blocks after drop coating. With water in excess in the mixed solution, an instant precipitation of CuI random aggregates takes place due to rapid crystal growth via ion-by-ion attachment induced by a strong antisolvent effect. However, this uncontrolled process can be modified by adding polymer polyvinyl pyrrolidone (PVP) in water to restrict the size of initially formed CuI crystal nuclei through the effective coordination effect of PVP. As a result, CuI superstructures with a cuboid geometry are constructed by gradual self-assembly of the small CuI crystals via oriented attachment. The precipitated CuI superstructures have been used as competent adsorbents to remove organic dyes from the water due to their mesocrystal feature. Besides, the CuI superstructures have been applied either as a self-sacrificial template or only as a structuring template for the flexible design of other porous materials such as CuO and TiO2. This system provides an ideal platform to simultaneously investigate the superstructure formation enforced by antisolvent crystallization with and without organic additives.

  14. 二氧化锰晶型对吡哆醇氧化反应的稳定性研究%The Effect of MnO2 Crystals on the Oxidation of Pyridoxine

    Institute of Scientific and Technical Information of China (English)

    施湘君; 陈巧巧

    2012-01-01

    Pyridoxal(1) was synthesized from pyridoxine(2) by manganese dioxide. The crystal form of different commercial MnO2 was characterized via X-ray diffraction. We found the different crystal form of MnO2 influenced the result of oxidizing reaction, and γα- MnO2 is the most effective form.%以吡哆醇(1)为起始原料,经二氧化锰选择性氧化反应制得吡哆醛(2),通过X射线衍射脚)分析不同市售二氧化锰的晶型,研究不同晶型对催化氧化能力的影响,发现较优的晶型为γα-MnO2(混铆。

  15. Persistent Microvascular Obstruction After Myocardial Infarction Culminates in the Confluence of Ferric Iron Oxide Crystals, Proinflammatory Burden, and Adverse RemodelingCLINICAL PERSPECTIVE

    Energy Technology Data Exchange (ETDEWEB)

    Kali, Avinash; Cokic, Ivan; Tang, Richard; Dohnalkova, Alice; Kovarik, Libor; Yang, Hsin-Jung; Kumar, Andreas; Prato, Frank S.; Wood, John C.; Underhill, David; Marbán, Eduardo; Dharmakumar, Rohan

    2016-11-01

    Emerging evidence now supports the notion that persistent microvascular obstruction (PMO) may be more predictive of major adverse cardiovascular events than MI size itself. But, how PMO, a phenomenon limited to the acute/sub-acute period of MI, imparts adverse remodeling throughout the post MI period, particularly after its resolution, is incompletely understood. We hypothesized that PMOs resolve into chronic iron crystals within MI territories and actively impart a proinflammatory burden and adverse remodeling of infarction and LV in the chronic phase of MI. Canine models reperfused (n=20) and non-reperfused (n=20) with and without PMO were studied with serial cardiac MRI to characterize the spatiotemporal relationships between PMO, iron deposition, and infarct and LV remodeling indices between acute (day 7, post MI) and chronic (week 8, post MI). Histopathology and immunohistochemistry were used to validate the iron deposition, microscopically map and quantify the relationship between iron-rich chronic MI regions against pro-inflammatory macrophages, proinflammatory cytokines and matrix metalloproteinase. Atomic resolution transmission electron microscopy (TEM) was used to determine the crystallinity of iron and assess the physical effects of iron on lysosomes within macrophages, and energy-dispersive X-ray spectroscopy (EDS) to identify the chemical composition of the iron composite. Results showed that PMOs lead to iron deposition within chronic MI and that the extent of chronic iron deposition is strongly related to PMO Volume (r>0.6, p<0.001). TEM and EDS analysis showed that iron within chronic MI is found within macrophages as aggregates of nanocrystals of ~2.5 nm diameter in ferric state. Correlative histological studies showed that iron content, proinflammatory burden and collagen degrading enzyme were highly correlated (r >0.7, p<0.001). Iron within chronic MI was significantly associated with infarct resorption (r>0.5, p<0.001) and adverse structural (r

  16. Synthesis and characterisation of nanostructured neodymium titanium oxides by sol-gel process: Controlling the phase composition, crystal structure and grain size

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, M.R., E-mail: mrm41@cam.ac.uk [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Street, Tehran (Iran, Islamic Republic of); Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Fray, D.J., E-mail: djf25@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)

    2010-08-01

    Nanocrystalline neodymium titanium oxide thin films and powders with different phase compositions with mesoporous structure were produced by a straightforward particulate sol-gel route. The sols were prepared in various Nd:Ti molar ratios and they showed a narrow particle size distribution in the range 20-26 nm. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that the powders contained mixtures of Nd{sub 4}Ti{sub 9}O{sub 24}, Nd{sub 2}Ti{sub 4}O{sub 11}, Nd{sub 3}Ti{sub 4}O{sub 12} for titanium dominant powders (Nd:Ti {<=} 45:60), mixtures of Nd{sub 2}TiO{sub 5} and Nd{sub 2}O{sub 3} for neodymium dominant powders (Nd:Ti {>=} 75:25) and pure Nd{sub 3}Ti{sub 4}O{sub 12} phase for equal molar ratio of Nd:Ti, depending on the annealing temperature and Nd:Ti molar ratio. Moreover, it was found that Nd:Ti molar ratio influences the preferable orientation growth of the neodymium titanium oxide compounds. Transmission electron microscope (TEM) images confirmed that the average crystallite size of the powders annealed at 400 {sup o}C was in the range 1.0-2.8 nm and a gradual increase was occurred up to 6.7 nm by heat treatment at 1000 {sup o}C. The activation energy of crystal growth reduced with a decrease of Nd:Ti molar ratio, calculated in the range 6.90-18.12 kJ mol{sup -1}. Low activation energies indicating that the grain size will not change much with increase in temperature. Field emission scanning electron microscope (FE-SEM) analysis revealed that the deposited thin films had uniform, mesoporous and nanocrystalline structure. Moreover, atomic force microscope (AFM) images presented that the thin films had a columnar like morphology with average grain size in the range 17-30 nm at 600 {sup o}C and 47-60 nm at 800 {sup o}C, depending upon the Nd:Ti molar ratio. Based on Brunauer-Emmett-Taylor (BET) analysis, the synthesized powders showed mesoporous structure containing pores with sphere like shapes. The surface area of the

  17. Economic analysis of crystal growth in space

    Science.gov (United States)

    Ulrich, D. R.; Chung, A. M.; Yan, C. S.; Mccreight, L. R.

    1972-01-01

    Many advanced electronic technologies and devices for the 1980's are based on sophisticated compound single crystals, i.e. ceramic oxides and compound semiconductors. Space processing of these electronic crystals with maximum perfection, purity, and size is suggested. No ecomonic or technical justification was found for the growth of silicon single crystals for solid state electronic devices in space.

  18. Tailoring oxides of copper-Cu{sub 2}O and CuO nanoparticles and evaluation of organic dyes degradation

    Energy Technology Data Exchange (ETDEWEB)

    Raghav, Ragini; Aggarwal, Priyanka; Srivastava, Sudha, E-mail: sudha.srivastava@jiit.ac.in [Department of Biotechnology, Jaypee Institute of Information Technology, A-10, Sector-62, Noida-201307,Uttar Pradesh (India)

    2016-04-13

    We report a simple one-pot colloidal synthesis strategy tailoring cuprous or cupric nano-oxides in pure state. NaOH provided alkaline conditions (pH 12.5 -13) for nano-oxides formation, while its concentration regulated the oxidation state of the nano-oxides. The morphological, structural and optical properties of synthesized Cu{sub 2}O and CuO nanoparticles were studied by transmission electron microscopy (TEM), X-Ray diffraction (XRD) and UV-vis spectroscopy. Dye degradation capability of CuO and Cu2O nanoparticles was evaluated using four organic dyes - Malachite green, Methylene blue, Methyl orange and Methyl red. The results demonstrate effective degradation of all four dyes employing with almost comparable activity both Cu{sub 2}O and CuO nanoparticles.

  19. Tailoring oxides of copper-Cu2O and CuO nanoparticles and evaluation of organic dyes degradation

    Science.gov (United States)

    Raghav, Ragini; Aggarwal, Priyanka; Srivastava, Sudha

    2016-04-01

    We report a simple one-pot colloidal synthesis strategy tailoring cuprous or cupric nano-oxides in pure state. NaOH provided alkaline conditions (pH 12.5 -13) for nano-oxides formation, while its concentration regulated the oxidation state of the nano-oxides. The morphological, structural and optical properties of synthesized Cu2O and CuO nanoparticles were studied by transmission electron microscopy (TEM), X-Ray diffraction (XRD) and UV-vis spectroscopy. Dye degradation capability of CuO and Cu2O nanoparticles was evaluated using four organic dyes - Malachite green, Methylene blue, Methyl orange and Methyl red. The results demonstrate effective degradation of all four dyes employing with almost comparable activity both Cu2O and CuO nanoparticles.

  20. Rebamipide Suppresses Monosodium Urate Crystal-Induced Interleukin-1β Production Through Regulation of Oxidative Stress and Caspase-1 in THP-1 Cells.

    Science.gov (United States)

    Kim, Seong-Kyu; Choe, Jung-Yoon; Park, Ki-Yeun

    2016-02-01

    This study investigated the effect of rebamipide on activation of the NLRP3 inflammasome and generation of reactive oxygen species (ROS) in monosodium urate (MSU) crystal-induced interleukin-1β (IL-1β) production. Human monocyte cell line THP-1 and human umbilical venous endothelial cells (HUVECs) were used to assess the inflammatory response to MSU crystals. NADP/NADPH activity assays were used as a marker of ROS generation. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were performed to evaluate levels of IL-1β, caspase-1, NLRP3, associated speck-like protein (ASC), nuclear factor-κB (NF-κB), p65, IκBα, intercellular adhesion molecule 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1). Experimental pharmaceuticals included rebamipide, colchicine, dexamethasone, and ascorbic acid. In THP-1 cells, treatment with MSU crystals increased NADP/NADPH ratios and IL-1β expression, and both of these responses were potently inhibited by addition of rebamipide. Rebamipide also attenuated enhanced expression of caspase-1 gene by MSU crystals (p rebamipide. Stimulation of HUVECs with MSU crystals increased expression of VCAM-1 and ICAM-1, which were markedly inhibited by both rebamipide and dexamethasone. This study demonstrated that rebamipide inhibits IL-1β activation through suppression of ROS-mediated NF-κB signaling pathways and caspase-1 activation in MSU crystal-induced inflammation.

  1. EELS and electron diffraction studies on possible bonaccordite crystals in pressurized water reactor fuel CRUD and in oxide films of alloy 600 material

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jiaxin [Studsvik Nuclear AB, Nykoping (Sweden); Lindberg, Fredrik [Swerea KIMAB AB, Kista (Sweden); Wells, Daniel [Electric Power Research Institute, Charlotte (United States); Bengysson, Bernt [Ringhals AB, Ringhalsverket, Varobacka (Sweden)

    2017-06-15

    Experimental verification of boron species in fuel CRUD (Chalk River Unidentified Deposit) would provide essential and important information about the root cause of CRUD-induced power shifts (CIPS). To date, only bonaccordite and elemental boron were reported to exist in fuel CRUD in CIPS-troubled pressurized water reactor (PWR) cores and lithium tetraborate to exist in simulated PWR fuel CRUD from some autoclave tests. We have reevaluated previous analysis of similar threadlike crystals along with examining some similar threadlike crystals from CRUD samples collected from a PWR cycle that had no indications of CIPS. These threadlike crystals have a typical [Ni]/[Fe] atomic ratio of ⁓2 and similar crystal morphology as the one (bonaccordite) reported previously. In addition to electron diffraction study, we have applied electron energy loss spectroscopy to determine boron content in such a crystal and found a good agreement with that of bonaccordite. Surprisingly, such crystals seem to appear also on corroded surfaces of Alloy 600 that was exposed to simulated PWR primary water with a dissolved hydrogen level of 5 mL H{sub 2}/kg H{sub 2}O, but absent when exposed under 75 mL H{sub 2}/kg H{sub 2}O condition. It remains to be verified as to what extent and in which chemical environment this phase would be formed in PWR primary systems.

  2. EELS and electron diffraction studies on possible bonaccordite crystals in pressurized water reactor fuel CRUD and in oxide films of alloy 600 material

    Directory of Open Access Journals (Sweden)

    Jiaxin Chen

    2017-06-01

    Full Text Available Experimental verification of boron species in fuel CRUD (Chalk River Unidentified Deposit would provide essential and important information about the root cause of CRUD-induced power shifts (CIPS. To date, only bonaccordite and elemental boron were reported to exist in fuel CRUD in CIPS-troubled pressurized water reactor (PWR cores and lithium tetraborate to exist in simulated PWR fuel CRUD from some autoclave tests. We have reevaluated previous analysis of similar threadlike crystals along with examining some similar threadlike crystals from CRUD samples collected from a PWR cycle that had no indications of CIPS. These threadlike crystals have a typical [Ni]/[Fe] atomic ratio of ∼2 and similar crystal morphology as the one (bonaccordite reported previously. In addition to electron diffraction study, we have applied electron energy loss spectroscopy to determine boron content in such a crystal and found a good agreement with that of bonaccordite. Surprisingly, such crystals seem to appear also on corroded surfaces of Alloy 600 that was exposed to simulated PWR primary water with a dissolved hydrogen level of 5 mL H2/kg H2O, but absent when exposed under 75 mL H2/kg H2O condition. It remains to be verified as to what extent and in which chemical environment this phase would be formed in PWR primary systems.

  3. Treatment of port-wine stains by photodynamic therapy of cuprous bromide laser%溴化亚铜激光光动力学疗法治疗鲜红斑痣

    Institute of Scientific and Technical Information of China (English)

    唐建民; 刘爱琴; 陈祖林; 杨名娟

    2000-01-01

    运用溴化亚铜激光光动力学疗法治疗鲜红斑痣296例,红斑完全消退185例(62.5%),部分消退111例(37.5%),无效0,并发疤痕15例,证实该疗法疗效确切同时仍需完善。%296 Cases of port-wine stains(PWS) were treated by photodynamic therapy(PDT) of cuprous bromide laser,including which 185 cases (62.5%)gained the result of thorough remission,111 cases (37.5%)gained the result of partial remission and 15 cases complicated with scar formation.PDT is proved to be an effective therapy for PWS while it also needs improving.

  4. The effect of oxide shell thickness on the structural, electronic, and optical properties of Si-SiO2 core-shell nano-crystals: A (time dependent)density functional theory study

    Science.gov (United States)

    Nazemi, Sanaz; Pourfath, Mahdi; Soleimani, Ebrahim Asl; Kosina, Hans

    2016-04-01

    Due to their tunable properties, silicon nano-crystals (NC) are currently being investigated. Quantum confinement can generally be employed for size-dependent band-gap tuning at dimensions smaller than the Bohr radius (˜5 nm for silicon). At the nano-meter scale, however, increased surface-to-volume ratio makes the surface effects dominant. Specifically, in Si-SiO2 core-shell semiconductor NCs the interfacial transition layer causes peculiar electronic and optical properties, because of the co-existence of intermediate oxidation states of silicon (Sin+, n = 0-4). Due to the presence of the many factors involved, a comprehensive understanding of the optical properties of these NCs has not yet been achieved. In this work, Si-SiO2 NCs with a diameter of 1.1 nm and covered by amorphous oxide shells with thicknesses between 2.5 and 4.75 Å are comprehensively studied, employing density functional theory calculations. It is shown that with increased oxide shell thickness, the low-energy part of the optical transition spectrum of the NC is red shifted and attenuated. Moreover, the absorption coefficient is increased in the high-energy part of the spectrum which corresponds to SiO2 transitions. Structural examinations indicate a larger compressive stress on the central silicon cluster with a thicker oxide shell. Examination of the local density of states reveals the migration of frontier molecular orbitals from the oxide shell into the silicon core with the increase of silica shell thickness. The optical and electrical properties are explained through the analysis of the density of states and the spatial distribution of silicon sub-oxide species.

  5. Crystal and Molecular Structure of N-(1-Ethoxycarbonyl-ethyl) 1-Ethoxycarbonylmethyl-3-ethyl-1,2,3,4-tetrahydro-4-oxo-1,3,2-benzodiazaphosphorin-2-carboxamide 2-Oxide

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The crystal structure of the title compound N-(1-ethoxycarbonyl-ethyl) 1-ethoxycarbonylmethy-3-ethyl-1,2,3,4-tetrahydro-4-oxo-1,3,2-benzodiazaphosphorin-2-carbox amide 2-oxide, (C19H26N3O7P, Mr = 439.41), was determined by single crystal X-ray diffraction at 299(1) K. It crystallizes in the triclinic system, space group P _ 1 (No.2) with a = 8.955(2), b = 11.863(2), c = 12.309(2) ?, a = 62.67(3),β= 68.10(3), g = 78.07(3)°, V = 1077(1) ?3, Z = 2, Dx =1.355 g·cm-3, l = 0.71073 ?, m = 0.1657 mm-1 and F(000) = 464. The structure was solved by direct methods. The final R factor is 0.071 and Rw is 0.076 for 2176 observed reflections with I ≥3s(I). The results from X-ray crystallography analysis of the isomer with 31P NMR spectra exhibited as d 4.09 show that the absolute configuration of the chiral phosphorus atom at P(1) was proved to be S-form, with reference to the known configuration of R-alanine moiety.

  6. Crystal structures of 2,3-bis(4-chlorophenyl-1,3-thiazolidin-4-one and trans-2,3-bis(4-chlorophenyl-1,3-thiazolidin-4-one 1-oxide

    Directory of Open Access Journals (Sweden)

    Hemant P. Yennawar

    2015-03-01

    Full Text Available In the crystal structures of the title compounds, C15H11Cl2NOS, (1, and C15H11Cl2NO2S, (2, wherein (2 is the oxidized form of (1, the thiazolidine ring is attached to two chlorophenyl rings. The chlorophenyl ring on the 2-carbon atom position points in the same direction as that of the S atom in (1, while in (2, the S atom points in the opposite direction. The O atom on the chiral S atom in (2 is trans to the chlorophenyl ring on the 2-carbon. The chlorophenyl ring planes in each structure are close to orthogonal, making dihedral angles of 78.61 (6 and 87.46 (8° in (1 and (2, respectively. The thiazolidine ring has a twisted conformation on the S—Cmethine bond in (1, and an envelope conformation with the S atom 0.715 (3 Å out of the plane of other four atoms in (2. In the crystal of (1, molecules are linked by C—H...O hydrogen bonds, as well as by slipped parallel π–π interactions [inter-centroid distance = 3.840 (3 Å] between inversion-related phenyl rings, forming sheets parallel to (001. In the crystal of (2, molecules are linked via C—H...O and C—H...Cl hydrogen bonds, forming slabs parallel to (001.

  7. Crystallization and Preliminary X-ray Analysis of Allene Oxide Synthase, Cytochrome P450 CYP74A2, from Parthenium argentatum

    Science.gov (United States)

    Oxylipins are oxygenated derivatives of fatty acids and pivotal signaling molecules in plants and animals. Allene oxide synthase (AOS) is a key cytochrome P450 CYP74 enzyme involved in the biosynthesis of plant oxylipin jasmonates to convert 13(S)-hydroperoxide to allene oxide. Guayule (Parthenium a...

  8. Synthesis and Crystal Structure of Cis 2-(6- Chloro-3-pyridylmethylamino)-4-chlorophenyl-5,5-dimethyl-1,3,2-dioxaphosphinane 2-Oxides

    Institute of Scientific and Technical Information of China (English)

    刘漪; 魏佳; 石德清; 王成刚

    2005-01-01

    The crystal structure of the title compound (C17H19Cl2N2O3P, Mr= 401.21) has been determined by single-crystal X-ray diffraction. The crystal is of monoclinic, space group P21/n with a = 6.1648(6), b = 19.943(2), c = 15.268(2) (A),β = 99.220(2)°, V = 1852.8(3) (A)3, Z = 4, Dc = 1.438 g/cm3, F(000) = 832,μ(MoKa) = 0.456 mm-1, the final R = 0.0622 and wR = 0.1586 for 3986 observed reflections (I > 2σ(I)). X-ray analysis reveals that the product is a thermodynamically stable cis isomer. The intramolecular hydrogen bond N(2)-H(2A)…O(1) is observed in the title compound.

  9. Axion Crystals

    CERN Document Server

    Ozaki, Sho

    2016-01-01

    The low-energy effective theories for gapped insulators are classified by three parameters: permittivity $\\epsilon$, permeability $\\mu$, and theta angle $\\theta$. Crystals with periodic $\\epsilon$ are known as photonic crystals. We here study the band structure of photons in a new type of crystals with periodic $\\theta$ (modulo $2\\pi$) in space, which we call the axion crystals. We find that the axion crystals have a number of new properties that the usual photonic crystals do not possess, such as the helicity-dependent photonic band gaps and the nonrelativistic gapless dispersion relation at small momentum. We briefly discuss possible realizations of axion crystals in condensed matter systems as well as high-energy physics.

  10. Coordination of lanthanide cation to an Anderson type polyoxometalate anion leads to isomorphous metal-oxide based one-dimensional inorganic solids: Synthesis, crystal structure and spectroscopy

    Indian Academy of Sciences (India)

    Vaddypally Shivaiah; Tanmay Chatterjee; Samar K Das

    2014-09-01

    One-dimensional isomorphous inorganic polymers containing Anderson type heteropoly anion as a basic building unit, namely [La(H2O)7Cr(OH)6Mo6O18]·4nH2O (1), [Gd(H2O)7Cr(OH)6Mo6O18]·4nH2O (2), [Gd(H2O)7Al(OH)6Mo6O18]·4nH2O (3), and [Eu(H2O)7Al(OH)6Mo6O18]·4nH2O (4) have been synthesized and studied by the powdered X-ray diffraction, TGA, IR, electronic and ESR spectroscopy, and unambiguously by single crystal X-ray crystallography. Isomorphous compounds 1-4 are crystallized in orthorhombic system with 21 space group. The crystal structure analysis reveals a one-dimensional extended chain in which the Anderson type heteropolyanion, acting as the building unit, is linked by rare earth metal ions in a zig-zag fashion. In the crystal structure, all types of oxygens of the heteropolyanion, lattice waters, lanthanum coordinated waters are extensively involved in O—H…O hydrogen bonding interactions. Compounds are additionally characterized by UV-visible and ESR spectroscopy.

  11. High-pressure synthesis, crystal structures, and magnetic properties of 5d double-perovskite oxides Ca2MgOsO6 and Sr2MgOsO6.

    Science.gov (United States)

    Yuan, Yahua; Feng, Hai L; Ghimire, Madhav Prasad; Matsushita, Yoshitaka; Tsujimoto, Yoshihiro; He, Jianfeng; Tanaka, Masahiko; Katsuya, Yoshio; Yamaura, Kazunari

    2015-04-06

    Double-perovskite oxides Ca2MgOsO6 and Sr2MgOsO6 have been synthesized under high-pressure and high-temperature conditions (6 GPa and 1500 °C). Their crystal structures and magnetic properties were studied by a synchrotron X-ray diffraction experiment and by magnetic susceptibility, specific heat, isothermal magnetization, and electrical resistivity measurements. Ca2MgOsO6 and Sr2MgOsO6 crystallized in monoclinic (P21/n) and tetragonal (I4/m) double-perovskite structures, respectively; the degree of order of the Os and Mg arrangement was 96% or higher. Although Ca2MgOsO6 and Sr2MgOsO6 are isoelectric, a magnetic-glass transition was observed for Ca2MgOsO6 at 19 K, while Sr2MgOsO6 showed an antiferromagnetic transition at 110 K. The antiferromagnetic-transition temperature is the highest in the family. A first-principles density functional approach revealed that Ca2MgOsO6 and Sr2MgOsO6 are likely to be antiferromagnetic Mott insulators in which the band gaps open, with Coulomb correlations of ∼1.8-3.0 eV. These compounds offer a better opportunity for the clarification of the basis of 5d magnetic sublattices, with regard to the possible use of perovskite-related oxides in multifunctional devices. The double-perovskite oxides Ca2MgOsO6 and Sr2MgOsO6 are likely to be Mott insulators with a magnetic-glass (MG) transition at ∼19 K and an antiferromagnetic (AFM) transition at ∼110 K, respectively. This AFM transition temperature is the highest among double-perovskite oxides containing single magnetic sublattices. Thus, these compounds offer valuable opportunities for studying the magnetic nature of 5d perovskite-related oxides, with regard to their possible use in multifunctional devices.

  12. Role of oxygen flow rate on the structural and optical properties of copper oxide thin films grown by reactive magnetron sputtering

    Science.gov (United States)

    Ali, M.; Gobinner, C. R.; Kekuda, D.

    2016-02-01

    Copper oxide thin films were grown by DC reactive magnetron sputtering. The structural investigation of the sputtered films was carried out using X-ray diffraction. The surface morphology of the films was observed through atomic force microscopy. A crossover in the crystalline phase from cuprous to cupric oxide (tenorite) was observed as a result of variation in the oxygen flow rate during sputtering. Deposition rate was also found to be a function of the oxygen flow rate, and it was found that the deposition rate decreased with an increase in the oxygen flow rate which could be attributed to the possible target oxidation at higher oxygen flow rates. Variation of grain size of the films with oxygen flow rate was analyzed through AFM analysis. Dependence of oxygen flow rate on the formation of two phases of copper oxide was also confirmed through the optical band gap measurements.

  13. Efficient visible light photocatalytic water oxidation on Zn{sub 3}(OH){sub 2}V{sub 2}O{sub 7}·2H{sub 2}O nanoplates: Effects of exposed facet and local crystal structure distortion

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lingling; Tang, Yiwen; Tong, Liping; Zhou, Han; Ding, Jian; Fan, Tongxiang, E-mail: txfan@sjtu.edu.cn; Zhang, Di

    2015-08-15

    Highlights: • Zn{sub 3}(OH){sub 2}V{sub 2}O{sub 7}·2H{sub 2}O nanoplates were hydrothermally fabricated at different pH values. • The morphology and local crystal structure of sample has a close relationship with pH. • Sample prepared at low pH exhibited the highest photocatalytic water oxidation ability. • The H{sub 2}O molecule adsorption on different exposed facets was investigated by DFT. - Abstract: Zn{sub 3}(OH){sub 2}V{sub 2}O{sub 7}·2H{sub 2}O samples with high visible-light photocatalytic water oxidation activity were hydrothermally fabricated at different pH conditions. The crystalline phase, morphology and local crystal structure were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transition electron microscopy (TEM), corresponding selected area diffraction (SAED) and Raman techniques. According to the SEM results, all the samples exhibited aggregates of irregular nanoplates with the average diameter of 100–200 nm and thickness of ∼20 nm. Furthermore, some factors, such as pH conditions, influencing the morphologies and local crystal structure of the Zn{sub 3}(OH){sub 2}V{sub 2}O{sub 7}·2H{sub 2}O nanoplates have been systematically investigated. The photocatalytic activities of the Zn{sub 3}(OH){sub 2}V{sub 2}O{sub 7}·2H{sub 2}O were evaluated by photocatalytic water oxidation under visible light irradiation. It was found that Zn{sub 3}(OH){sub 2}V{sub 2}O{sub 7}·2H{sub 2}O prepared at low pH exhibited high photocatalytic water oxidation activity, indicating that different morphologies and the different extent of local crystal structure distortion can effectively influence the water oxidation activity of Zn{sub 3}(OH){sub 2}V{sub 2}O{sub 7}·2H{sub 2}O. Moreover, the relationship between the exposed facets of Zn{sub 3}(OH){sub 2}V{sub 2}O{sub 7}·2H{sub 2}O and the H{sub 2}O molecule adsorption was investigated by density functional theory (DFT). The results of our study indicated that the extent of

  14. RNA Crystallization

    Science.gov (United States)

    Golden, Barbara L.; Kundrot, Craig E.

    2003-01-01

    RNA molecules may be crystallized using variations of the methods developed for protein crystallography. As the technology has become available to syntheisize and purify RNA molecules in the quantities and with the quality that is required for crystallography, the field of RNA structure has exploded. The first consideration when crystallizing an RNA is the sequence, which may be varied in a rational way to enhance crystallizability or prevent formation of alternate structures. Once a sequence has been designed, the RNA may be synthesized chemically by solid-state synthesis, or it may be produced enzymatically using RNA polymerase and an appropriate DNA template. Purification of milligram quantities of RNA can be accomplished by HPLC or gel electrophoresis. As with proteins, crystallization of RNA is usually accomplished by vapor diffusion techniques. There are several considerations that are either unique to RNA crystallization or more important for RNA crystallization. Techniques for design, synthesis, purification, and crystallization of RNAs will be reviewed here.

  15. Pressure-induced melting of micellar crystal

    DEFF Research Database (Denmark)

    Mortensen, K.; Schwahn, D.; Janssen, S.

    1993-01-01

    Aqueous solutions of triblock copolymers of poly(ethylene oxide) and poly(propylene oxide) aggregate at elevated temperatures into micelles which for polymer concentrations greater-than-or-equal-to 20% make a hard sphere crystallization to a cubic micellar crystal. Structural studies show...... that pressure improves the solvent quality of water, thus resulting in decomposition of the micelles and consequent melting of the micellar crystal. The combined pressure and temperature dependence reveals that in spite of the apparent increase of order on the 100 angstrom length scale upon increasing...... temperature (decreasing pressure) the overall entropy increases through the inverted micellar crystallization characteristic....

  16. Protein Crystallization

    Science.gov (United States)

    Chernov, Alexander A.

    2005-01-01

    Nucleation, growth and perfection of protein crystals will be overviewed along with crystal mechanical properties. The knowledge is based on experiments using optical and force crystals behave similar to inorganic crystals, though with a difference in orders of magnitude in growing parameters. For example, the low incorporation rate of large biomolecules requires up to 100 times larger supersaturation to grow protein, rather than inorganic crystals. Nucleation is often poorly reproducible, partly because of turbulence accompanying the mixing of precipitant with protein solution. Light scattering reveals fluctuations of molecular cluster size, its growth, surface energies and increased clustering as protein ages. Growth most often occurs layer-by-layer resulting in faceted crystals. New molecular layer on crystal face is terminated by a step where molecular incorporation occurs. Quantitative data on the incorporation rate will be discussed. Rounded crystals with molecularly disordered interfaces will be explained. Defects in crystals compromise the x-ray diffraction resolution crucially needed to find the 3D atomic structure of biomolecules. The defects are immobile so that birth defects stay forever. All lattice defects known for inorganics are revealed in protein crystals. Contribution of molecular conformations to lattice disorder is important, but not studied. This contribution may be enhanced by stress field from other defects. Homologous impurities (e.g., dimers, acetylated molecules) are trapped more willingly by a growing crystal than foreign protein impurities. The trapped impurities induce internal stress eliminated in crystals exceeding a critical size (part of mni for ferritin, lysozyme). Lesser impurities are trapped from stagnant, as compared to the flowing, solution. Freezing may induce much more defects unless quickly amorphysizing intracrystalline water.

  17. Synthesis, crystal structure, and electronic properties of high-pressure PdF2-type oxides MO2 (M = Ru, Rh, Os, Ir, Pt).

    Science.gov (United States)

    Shirako, Yuichi; Wang, Xia; Tsujimoto, Yoshihiro; Tanaka, Kie; Guo, Yanfeng; Matsushita, Yoshitaka; Nemoto, Yoshihiro; Katsuya, Yoshio; Shi, Youguo; Mori, Daisuke; Kojitani, Hiroshi; Yamaura, Kazunari; Inaguma, Yoshiyuki; Akaogi, Masaki

    2014-11-03

    The polycrystalline MO2's (HP-PdF2-type MO2, M = Rh, Os, Pt) with high-pressure PdF2 compounds were successfully synthesized under high-pressure conditions for the first time, to the best of our knowledge. The crystal structures and electromagnetic properties were studied. Previously unreported electronic properties of the polycrystalline HP-PdF2-type RuO2 and IrO2 were also studied. The refined structures clearly indicated that all compounds crystallized into the HP-PdF2-type structure, M(4+)O(2-)2, rather than the pyrite-type structure, M(n+)(O2)(n-) (n superconductivity nor a magnetic transition was detected down to a temperature of 2 K, unlike the case of 3d transition metal chalcogenide pyrites.

  18. Frequency down-conversion of 1 μm laser radiation to the mid-IR using non-oxide nonlinear crystals in a cascaded intracavity configuration

    Science.gov (United States)

    Petrov, Valentin; Boyko, Andrey A.; Kostyukova, Nadezhda Y.; Marchev, Georgi M.; Pasiskevicius, Valdas; Kolker, Dmitry B.; Badikov, Valeriy; Badikov, Dmitrii; Shevyrdyaeva, Galina; Zukauskas, Andrius; Panyutin, Vladimir

    2017-02-01

    A singly-resonant OPO (SRO) based on AgGaSe2 (AGSe) intracavity pumped at 1.85 μm by the signal pulses of a Rb:PPKTP doubly-resonant OPO (DRO) provided extremely broad tuning (5.8 to 18 μm) for the non-resonated idler. In a similar set-up with the same nonlinear crystals, we studied intracavity difference-frequency generation (DFG). Both AGSe and the new monoclinic crystal BaGa4Se7 (BGSe) generated single pulse energies of 0.7 mJ near 7 μm at an overall conversion efficiency from the 1.064 μm pump of 1.2%. The main advantage of BGSe is its damage resistivity up to the maximum pump levels applied at 100 Hz.

  19. The crystal structure of baliczunicite, Bi2O(SO4)2, a new natural bismuth oxide sulfate

    DEFF Research Database (Denmark)

    Pinto, Daniela; Garavelli, Anna; Balic Zunic, Tonci

    2015-01-01

    The crystal structure of baliczunicite, Bi2O(SO4)2, a new mineral species from the La Fossa crater of Vulcano (Aeolian Islands, Italy), was solved from single-crystal X-ray diffraction data and refined to R = 0.0507. The structure is triclinic, space group P1¯, with a = 6.7386(3), b = 11.1844(5), c...... parallel to the (100) plane. The planes are stacked atom on atom such that Bi always overlays S and vice versa. This structural feature is shared with the known structure of the high-temperature polymorph of the same compound, stable at T >535oC. However, the sequences of Bi and S atoms in the two...

  20. Computational crystallization.

    Science.gov (United States)

    Altan, Irem; Charbonneau, Patrick; Snell, Edward H

    2016-07-15

    Crystallization is a key step in macromolecular structure determination by crystallography. While a robust theoretical treatment of the process is available, due to the complexity of the system, the experimental process is still largely one of trial and error. In this article, efforts in the field are discussed together with a theoretical underpinning using a solubility phase diagram. Prior knowledge has been used to develop tools that computationally predict the crystallization outcome and define mutational approaches that enhance the likelihood of crystallization. For the most part these tools are based on binary outcomes (crystal or no crystal), and the full information contained in an assembly of crystallization screening experiments is lost. The potential of this additional information is illustrated by examples where new biological knowledge can be obtained and where a target can be sub-categorized to predict which class of reagents provides the crystallization driving force. Computational analysis of crystallization requires complete and correctly formatted data. While massive crystallization screening efforts are under way, the data available from many of these studies are sparse. The potential for this data and the steps needed to realize this potential are discussed.

  1. Drastic changes of electronic structure and crystal chemistry upon oxidation of SnII2TiO4E2 into SnIV2TiO6: An ab initio study

    Science.gov (United States)

    Matar, Samir F.; Maglione, Mario; Nakhl, Michel; Kfoury, Charbel N.; Etourneau, Jean

    2016-09-01

    From DFT based calculations establishing energy-volume equations of state and electron localization mapping, the electronic structure and crystal chemistry changes from Sn2TiO4 to Sn2TiO6 by oxidation are rationalized; the key effect being the destabilization of divalent tin SnII towards tetravalent state SnIV leading to rutile Sn2TiO6 as experimentally observed. The subsequent electronic structure change is highlighted in the relative change of the electronic band gap which increases from ∼1 eV up to 2.2 eV and the 1.5 times increase of the bulk modulus assigned to the change from covalently SnII based compound to the more ionic SnIV one. Such trends are also confronted with the relevant properties of black SnIIO.

  2. Synthesis, Structure and Antitumor Activity of Dibutyltin Oxide Complexes with 5-Fluorouracil Derivatives. Crystal Structure of [(5-Fluorouracil-1-CH2CH2COOSn(n-Bu 2]4O2

    Directory of Open Access Journals (Sweden)

    Zhan Shi

    2001-07-01

    Full Text Available Dibutyltin (IV oxide complex reacts with the fluorouracil compounds 5-fluorouracil-1-propanonic or 5-fluorouracil-1-acetic acid (Fu to give the complexes [(5-Fu-1-(CH2nCOOSn(n-Bu2]4O2 (I, n=2; II, n=1 which were characterized by IR and 1H-NMR. The crystal structure of complex I shows that the molecular is a dimer, in which two [(5-Fu-1-CH2CH2COOSn(n-Bu2]2O units are linked by a bridging oxygen atom, and the tin atoms adopt distorted trigonal bipyramids via two carbons from a dibutyl moiety and three oxygen atoms from 5-Fu and bridging oxygen. These complexes have potential anti-tumour activity: in vitro tests showed that complexes I and II exhibit high cytotoxicity against OVCAR-3 and PC-14.

  3. Crystal Data

    Science.gov (United States)

    SRD 3 NIST Crystal Data (PC database for purchase)   NIST Crystal Data contains chemical, physical, and crystallographic information useful to characterize more than 237,671 inorganic and organic crystalline materials. The data include the standard cell parameters, cell volume, space group number and symbol, calculated density, chemical formula, chemical name, and classification by chemical type.

  4. Crystal and Molecular Structure of N-Phenyl 1-Methoxycarbonylmethyl-3-benzyl-1,2,3,4- tetrahydro-4-oxo-1,3,2-benzodiazaphosphorin- 2-thiocarboxamide 2-Oxide

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The crystal structure of the title compound N-phenyl 1-methoxycarbonyl methy-3-benzyl-1,2,3,4-tetrahydro-4-oxo-1,3,2-benzodiazaphosphorin-2-thiocarboxamide 2-oxide, C24H22N3O4PS (Mr = 479.50), was determined by single-crystal X-ray diffraction at 299±1 K. It crystallizes in the triclinic system, space group P _ 1 with a = 10.555(2), b = 11.733(2), c = 12.191(2) ?, a = 60.50(3),β= 62.10(3), g = 75.09(3)°, V = 1161(1) ?3, Z = 2, Dx =1.372 g·cm-3, l = 0.71073 ?, m = 0.2351 mm-1 and F(000) = 500. The structure was solved by direct methods. The final R factor is 0.046 and Rw is 0.061 for 3246 observed reflections with I ≥3s(I). The results presented herein indicate that in the phosphorus-containing bicyclic moiety, atoms C(21), C(22), C(23), C(24), C(25), C(26), C(27), N(3) and N(2) are nearly coplanar. Moreover, the proximate thiocarbonyl and phosphoryl groups are nearly coplanar, and the P=O bond is trans-parallel to the C=S bond. Molecular packing in unit cell reveals that the two adjacent molecules are symmetrically linked to each other in dimers by two hydrogen bonds which connected the nitrogen atom of one molecule to the phosphoryl oxygen atom of the other forming a ten-membered ring.

  5. 高温氧化物晶体界面非稳定性研究%Polyhedral Instability of High-temperature Oxide Crystal

    Institute of Scientific and Technical Information of China (English)

    金蔚青; 蔡丽霞; 潘志雷; 苗宇

    2000-01-01

    设计了一套模拟实验, 以获得关于晶体形态和界面非稳定性的差异的可靠数据,如高温溶液生长的骸晶和枝蔓晶. 这些实验是在高温实时观察装置(HITISOT)内进行的. 高温溶液晶体生长实验是在环形铂金丝炉圈内进行的. 炉圈直径为2mm. 铂金丝既起加热又起支撑熔体的作用. 选用KNbO3和Li2B4O7?的混合物进行晶体生长实验. 在只存在扩散机制的快速生长过程中,会形成不同的晶体不完整性,如晶面凹坑、骸晶和枝蔓晶. 采用淬火实验以分辨不同的KNbO3晶体形态,并用扫描电镜研究Li2B4O7溶体中KNbO3?晶体生长的形貌. 在一般情况下,当晶体在气液界面附近液相区成核时,会产?生晶体界面非稳定性. 导致晶体形状不稳定的溶液层的厚度为60. 通过扫描电镜观察,发现晶体在这一溶液层中由多面体晶变为枝蔓晶. 骸晶和枝蔓?晶的各向异性反映了KNbO3的立方特性,也反映了界面非稳定性是沿[110]晶?棱扩大的. [110]晶棱方向的分支证实了晶体生长形状的各向异性. 形成界面非?稳定性的临界尺寸为10. 与此相反,保持稳定的晶面形状是通过60厚度以下的溶液内的晶体生长来实现的. 晶体生长过程是由高温实时观察装置进行实时观察和记录的,并能观察到晶体固液界面处的热溶质对流(如微对流).%Model experiments were designed in order to obtain more reliable data on the diversity of some crystal forms and polyhedral instability-skeletal and dendritic growth in high 妕emperature solution growth. These experiments were performed by High Temperature In Situ Observation Technique. Most of our investigations on high temperature solution growth were performed in a loop-shaped Pt wire heater, having a diameter about 2mm. The Pt wire (0.2mm) was used to heat and suspend the solution. A mixture of KNbO3 (20wt%) and Li2B4O7 was chosen for growth. Rapid growth

  6. Synthesis, Crystal Structure and Cytotoxicity Evaluation of 2-Phenoxy-4H-spiro{naphtho[2,3-e][1,4,2] oxazaphosphinane-5,10-dione,1 ′-cyclohexane} 2-Oxide

    Institute of Scientific and Technical Information of China (English)

    WANG Bin; WANG Jie; MIAO Zhi-Wei; CHEN Ru-Yu

    2006-01-01

    2-Phenoxy-4H-spiro { naphtho[2,3-e] [ 1 ,4,2]oxazaphosphinane-5,10-dione, 1 ′-cyclohexane}2-oxide (C22H20NO5P) was synthesized by the Mannich-type reaction of 2-amino-3-hydroxy-1,4-naphthoquinone with phenyl phosphorodichloridite and cyclohexanone, and structurally characterized by single-crystal X-ray diffraction analysis. It crystallizes in monoclinic, space group P21/n with a = 7.9133(11), b = 13.0269(18), c = 19.091(3) (A), β = 101.906(2)°, V = 1925.6(5)(A)3, Z = 4, Mr = 409.36, Dc = 1.412 g/cm3, F(000) = 856,μ = 0.178 mm-1, S = 1.015, the final R =0.0381 and wR = 0.0906 for 2718 observed reflections with I > 2σ(Ⅰ) and 262 variable parameters.This compound may be used as DNA-intercalator. Its cytotoxic activities were also tested in vitro on four human tumor cell lines.

  7. Preparation, Crystal Structure, and Magnetic Studies of a New Sr 7Re 4O 19 Double Oxide and Its Relation to the Structure of Ba 7Ir 6O 19

    Science.gov (United States)

    Bramnik, K. G.; Ehrenberg, H.; Fuess, H.

    2001-08-01

    The complex oxide Sr7Re4O19 has been synthesized and its crystal structure was determined by X-ray diffraction powder data analysis (space group C2/m; a=13.6379(3) Å, b=5.6035(2) Å, c=10.3700(3) Å; β=98.348(2)°, Z=2, RI=0.018, RP=0.050). The compound crystallizes in a new structure type, which can be derived from the Ba7Ir6O19 structure by removing the Ir atoms from the middle octahedron of three face-sharing IrO6 octahedra units. This change results in the infinite cis-bridged chains of the ReO6 octahedra linked together by common corners. Each chain is connected with another one by the corner-sharing of each second ReO6 octahedron. The 10- and 12-coordinated Sr atoms are situated between these infinite structure fragments. Magnetic properties of the Sr7Re4O19 compound were studied by SQUID measurements.

  8. Crystallization of copper metaphosphate glass

    Science.gov (United States)

    Bae, Byeong-Soo; Weinberg, Michael C.

    1993-01-01

    The effect of the valence state of copper in copper metaphosphate glass on the crystallization behavior and glass transition temperature has been investigated. The crystallization of copper metaphosphate is initiated from the surface and its main crystalline phase is copper metaphosphate (Cu(PO)3),independent of the (Cu sup 2+)/(Cu(total)). However, the crystal morphology, the relative crystallization rates, and their temperature dependences are affected by the (Cu sup 2+)/(Cu (total)) ratio in the glass. On the other hand, the totally oxidized glass crystallizes from all over the surface. The relative crystallization rate of the reduced glass to the totally oxidized glass is large at low temperature, but small at high temperature. The glass transition temperature of the glass increases as the (Cu sup 2+)/(Cu(total)) ratio is raised. It is also found that the atmosphere used during heat treatment does not influence the crystallization of the reduced glass, except for the formation of a very thin CuO surface layer when heated in air.

  9. Preparation and Photocatalytic Sterilization Property of Cu_2O Nanostructure with Copper Anode Oxidation Method%Cu_2O纳米阵列的铜阳极氧化法制备及其光催化杀菌性能研究

    Institute of Scientific and Technical Information of China (English)

    闫丽丽; 王艳; 熊良斌; 李家麟; 某浩然; 王保强; 余颖

    2009-01-01

    本文通过阳极氧化法直接在铜片上生长出纳米氧化亚铜阵列,所得到的样品通过扫描电子显微镜(SEM),紫外可见漫反射(UV-Vis diffuser reflectance),X-射线光电子能谱(XPS)等方法进行了表征,并研究了不同形貌氧化亚铜的杀菌效果.实验结果表明:反应过程中在阳极液中加入一定量的CTAB,有助于氧化亚铜的定向生长.通过控制反应条件(如电流密度,温度,和反应时间),可以得到不同形貌的氧化亚铜.随着电流密度的增大,氧化亚铜的形貌从网状,片状到棒状进行转化.所得到氧化亚铜的禁带宽度为1.95 eV.用所得样品进行杀菌实验,1 h内棒状氧化亚铜的杀菌率达到90.85%,而其它形貌的氧化亚铜杀菌率只有50%左右,与空铜片的杀菌率30%相比,所制得氧化亚铜具有较好的杀菌效果.%Cuprous oxide nanostructures were prepared by the method of copper anode oxidation. The obtained cuprous oxide was characterized with the techques of scanning electron microscopy, UV-Vis diffuse reflectance and X-ray photoelectron spectroscopy. The sterilization property of the samples was also investigated. It is found that CTAB plays an important role in the directional growth of the cuprous oxide. By controlling the reaction condition, such as current density, temperature and the reaction time, we can get different morphologies of Cu_2O. With the increase of current density, the morphology of Cu_2O can be nanonet, nanosheet and nanorod arrays respectively. In addition, the nanorod cuprous oxide has the best activity in sterilization and the sterilization efficiency can reach 90.85% in an hour.

  10. Exsolution of Iron-Titanium Oxides in Magnetite in Miller Range (MIL) 03346 Nakhlite: Evidence for Post Crystallization Reduction in the Nakhlite Cumulate Pile

    Science.gov (United States)

    Righter, Kevin; Keller, L. P.; Rahman, Z.; Christoffersen, R.

    2012-01-01

    MIL 03346 is one of the most mesostasis-rich nakhlites [1] and thought to have equilibrated at oxygen fugacities near the fayalite-magnetite-quartz oxygen (FMQ) buffer ([2,3]). Studies of FeTi oxides in nakhlites have led to additional constraints on their equilibration temperatures and fO2s [4,5,6,7]. Comparison of these results to fO2s calculated for shergottites indicates that nakhlites are among the most oxidized samples from the martian meteorite suite [2]. The mesostasis of MIL 03346 contains skeletal titanomagnetite. Several scientists noticed several years ago (e.g. [8]) that this titanomagnetite contains very fine oxidation-driven exsolution lamellae (Figure 1). However, the lamellae are so small that they cannot be characterized by electron microprobe analysis (EMPA). Here we select several areas for focused ion beam (FIB) extraction, prepare transmission electron microscopy (TEM) foils, and identify and analyze the lamellae using TEM at the Johnson Space Center (JSC). The resulting analyses are combined with previous work on nakhlites to interpret the thermal and oxidation history of this meteorite group.

  11. Photocatalytic activities of tin(IV) oxide surface-modified titanium(IV) dioxide show a strong sensitivity to the TiO 2 crystal form

    OpenAIRE

    Jin, Qiliang; Fujishima, Musashi; Nolan, Michael; Iwaszuk, Anna; Tada, Hiroaki

    2012-01-01

    Surface modification of rutile TiO2 with extremely small SnO2 clusters gives rise to a great increase in its UV light activity for degradation of model organic water pollutants, while the effect is much smaller for anatase TiO2. This crystal form sensitivity is rationalized in terms of the difference in the electronic modification of TiO2 through the interfacial Sn−O−Ti bonds. The increase in the density of states near the conduction band minimum of rutile by hybridization with the SnO2 clust...

  12. 水相中金属铜表面生成亚铜-邻菲罗啉配合物的反应%FORMATION OF BIS ( 1 , 10-PHENANTHROLINE) CUPROUS COMPLEXES ON METALLIC COPPER SURFACE IN AQUEOUS SOLUTION

    Institute of Scientific and Technical Information of China (English)

    聂崇实; 顾亦君; 孙杰

    1996-01-01

    本文研究了零价铜在邻菲罗啉水溶液中的反应.当溶液敞露于空气并存在有机阴离子X-时,例如苯甲酸盐(Bz)、对甲基苯磺酸盐(Ts)等,铜的表面生成了致密的反应产物的薄层,经IR、UV/VIS、MS和元素分析证明了该薄层为相当纯的亚铜的邻菲罗啉配位化合物,结构为[Cu(phen)2]+X-.在乙醇/甲苯混合溶剂中得到了表面反应产物的晶体[Cu(phen)2](CH3C4H6SO3)C2HsOH,并用X-ray测得了结构.本工作表明溶液中的Cu1离子抑制Cu0氧化成Cu1而影响反应层的形成,同时又促进Cu1氧化成Cu1的过程.%The formation of cuprous complex on metallic copper surface in 1,10-phenanthroline (phen) aqueous solution has been investigated as exposed in air and in the presence of common organic anions (X-) such as benzoate (Bz-) and toluene sulphonate (Ts-). The complexes deposited on the surface of metallic copper have been proved to be rather pure cuprous phenanthroline complexes having the structure [Cu(phen)2]X based on the elemental analysis, IR, UV/C2H5OH was determined by X-ray diffraction analysis. The work demonstrated that the Cu1 ion in the reaction solution hindered the process of Cu0 to Cu1 and in the meanwhile accelerated the process of Cu 1 to Cu 1.

  13. Macromolecular crystallization and crystal perfection

    CERN Document Server

    Chayen, Naomi E; Snell, Edward H

    2010-01-01

    Structural biology is key to our understanding of the mechanisms of biological processes. This text describes current methods and future frontiers in crystal growth and use of X-ray and neutron crystallography, in the context of automation of crystallization and generation of synchrotron X-ray and neutron beams.

  14. Active Gold-Ceria and Gold-Ceria/titania Catalysts for CO Oxidation. From Single-Crystal Model Catalysts to Powder Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Jose A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Si, Rui [Brookhaven National Lab. (BNL), Upton, NY (United States); Evans, Jaime [Central Univ. of Venezuela, Caracas (Venezuela); Xu, Wenqian [Brookhaven National Lab. (BNL), Upton, NY (United States); Hanson, Jonathan C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Tao, Jing [Brookhaven National Lab. (BNL), Upton, NY (United States); Zhu, Yimei [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2014-07-23

    We studied CO oxidation on model and powder catalysts of Au-CeO2 and Au-CeOx/TiO2. Phenomena observed in Au-CeO2(1 1 1) and Au-CeO2/TiO2(1 1 0) provided useful concepts for designing and preparing highly active and stable Au-CeOx/TiO2 powder catalysts for CO oxidation. Small particles of Au dispersed on CeO2(1 1 1) displayed high catalytic activity, making Au-CeO2(1 1 1) a better CO oxidation catalyst than Au-TiO2(1 1 0) or Au-MgO(1 0 0). An excellent support for gold was found after depositing nanoparticles of ceria on TiO2(1 1 0). The CeOx nanoparticles act as nucleation centers for gold, improving dispersion of the supported metal and helping in the creation of reaction sites efficient for the adsorption of CO and the dissociation of the O2 molecule. High-surface area catalysts were prepared by depositing gold on ceria nanorods and CeOx/TiO2 powders. The samples were tested for the low-temperature (10–70 °C) oxygen-rich (1%CO/4%O2/He) CO oxidation reaction after pre-oxidation (20%O2/He, 300 °C) and pre-reduction (5%H2/He, 300 °C) treatments. Moreover, synchrotron-based operando X-ray diffraction (XRD) and X-ray absorption (XAS) spectroscopy were used to study the Au-CeO2 and Au-CeOx/TiO2 catalysts under reaction conditions. Our operando findings indicate that the most active phase of these catalysts for low-temperature CO oxidation consist of small particles of metallic Au dispersed on CeO2 or CeOx/TiO2.

  15. Liquid crystal tunable photonic crystal dye laser

    DEFF Research Database (Denmark)

    Buss, Thomas; Christiansen, Mads Brøkner; Smith, Cameron

    2010-01-01

    We present a dye-doped liquid crystal laser using a photonic crystal cavity. An applied electric field to the liquid crystal provides wavelength tunability. The photonic crystal enhances resonant interaction with the gain medium....

  16. Controlled growth of semiconductor crystals

    Science.gov (United States)

    Bourret-Courchesne, Edith D.

    1992-01-01

    A method for growth of III-V, II-VI and related semiconductor single crystals that suppresses random nucleation and sticking of the semiconductor melt at the crucible walls. Small pieces of an oxide of boron B.sub.x O.sub.y are dispersed throughout the comminuted solid semiconductor charge in the crucible, with the oxide of boron preferably having water content of at least 600 ppm. The crucible temperature is first raised to a temperature greater than the melt temperature T.sub.m1 of the oxide of boron (T.sub.m1 =723.degree. K. for boron oxide B.sub.2 O.sub.3), and the oxide of boron is allowed to melt and form a reasonably uniform liquid layer between the crucible walls and bottom surfaces and the still-solid semiconductor charge. The temperature is then raised to approximately the melt temperature T.sub.m2 of the semiconductor charge material, and crystal growth proceeds by a liquid encapsulated, vertical gradient freeze process. About half of the crystals grown have a dislocation density of less than 1000/cm.sup.2. If the oxide of boron has water content less than 600 ppm, the crucible material should include boron nitride, a layer of the inner surface of the crucible should be oxidized before the oxide of boron in the crucible charge is melted, and the sum of thicknesses of the solid boron oxide layer and liquid boron oxide layer should be at least 50 .mu.m.

  17. Crystal structures of a pentavalent bismuthate, SrBi2O6 and a lead bismuth oxide (Pb1/3Bi2/3O1.4

    Directory of Open Access Journals (Sweden)

    Nobuhiro Kumada

    2014-06-01

    Full Text Available The crystal structures of a pentavalent bismuthate, SrBi2O6 with the PbSb2O6-type structure and a lead bismuth oxide, (Pb1/3Bi2/3O1.4 with the fluorite-type structure were refined by using neutron diffraction data. The final R-factors were Rwp = 4.49, Rp = 3.46, RI = 4.50 and RF = 1.70% for SrBi2O6 and Rwp = 5.04, Rp = 3.93, RI = 5.47 and RF = 4.26% for (Pb1/3Bi2/3O1.4. SrBi2O6 prepared from NaBiO3·1.4H2O is the first example of the bismuthate with the PbSb2O6-type structure. The fluorite-type lead bismuth oxide, (Pb1/3Bi2/3O1.4 was obtained by heating the PbSb2O6-type lead bismuthate, PbBi2O5.9·H2O which was prepared also from NaBiO3·1.4H2O.

  18. Crystal Dislocations

    Directory of Open Access Journals (Sweden)

    Ronald W. Armstrong

    2016-01-01

    Full Text Available Crystal dislocations were invisible until the mid-20th century although their presence had been inferred; the atomic and molecular scale dimensions had prevented earlier discovery. Now they are normally known to be just about everywhere, for example, in the softest molecularly-bonded crystals as well as within the hardest covalently-bonded diamonds. The advent of advanced techniques of atomic-scale probing has facilitated modern observations of dislocations in every crystal structure-type, particularly by X-ray diffraction topography and transmission electron microscopy. The present Special Issue provides a flavor of their ubiquitous presences, their characterizations and, especially, their influence on mechanical and electrical properties.

  19. Synthesis and Crystal Structure of Fe(aapo)2Cl3 (aapo=2—Acetylamino Pyridine N—Oxide

    Institute of Scientific and Technical Information of China (English)

    LIXiu-Ling; YUKai-Bei; 等

    2003-01-01

    The complex Fe(aapo)2Cl3 with chemical formula C14H16Cl3FeN4O4 was obtained by the reaction of FeCl3.6H2O with apo.HCl(apo=2amino pyridine Noxide)in acetonitrile.The result shows that CH3CN has been hydrolysised with the water from FeCl3.6H2O dissolving,and then the hydrolysised product condenses with apo to give aapo.A single-crystal Xray study of Fe(aapo)2Cl3 shows it belongs to the monoclinic system,space group C2/c with a=15.873(3),b=10.322(2),c=11.987(2)°↑A,β=106.35(1)°V=1884.5(6)°↑A3,Z=4,Mr=466.51,Dc=1.644g/cm3,μ(Mokα)=1.253mm-1,F(000)=948,R=0.0377 wR=0.0749 for 1262 observed reflections with I>2σ(I),Fe(Ⅲ)is coordinated by a trigonal bipyramidal geometry with three cholorine atoms lying on the equatorial plane and two oxygen atoms connected with the nitrogen atoms of pyridine rings occupying the axial positions,while the iron and Cl(1) atoms lie on the crystallographic 2-fold axis.The dihedral angle of two pyridine rings is 71.74(9)° ,There exist N(2)-H(2)…O(1) hydrogen bonds in the crystal structure.

  20. Oxide meets silicide. Synthesis and single-crystal structure of Ca{sub 21}SrSi{sub 24}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Reckeweg, Olaf; DiSalvo, Francis J. [Cornell Univ., Ithaca, NY (United States). Dept. of Chemistry and Chemical Biology

    2017-06-01

    A few black, rectangular thin plates of Ca{sub 21}SrSi{sub 24}O{sub 2} were obtained by serendipity in a solid-state reaction of calcium metal, strontium chloride and silicon powder at 1200 K for 2 days designed to produce 'Ca{sub 2}SrCl{sub 2}[Si{sub 3}]'. The title compound forms next to some CaSi and some remaining educts. Ca{sub 21}SrSi{sub 24}O{sub 2} crystallizes in the monoclinic space group C2/m (no. 12) with unit cell parameters of a=1895.2(2), b=450.63(5) and c=1397.33(18) pm and β=112.008(7) (Z=1). The title compound shows planar, eight-membered, kinked Si{sub 8} chains with Si-Si distances between 241.4 and 245.0 pm indicating bonding interactions and kinked 'rope ladders' connecting the chains with interatomic Si-Si distances in the range 268.1-274.7 pm. Embedded in between these silicon substructures are columns of oxygen centered, apex sharing [(Ca{sub 1-x} Sr{sub x}){sub 6/2}O] octahedra and calcium ions.

  1. A novel copper (II) complex containing a tetradentate Schiff base: Synthesis, spectroscopy, crystal structure, DFT study, biological activity and preparation of its nano-sized metal oxide

    Science.gov (United States)

    Tohidiyan, Zeinab; Sheikhshoaie, Iran; Khaleghi, Mouj; Mague, Joel T.

    2017-04-01

    A new nano-sized copper (II) complex, [Cu(L)] with a tetra dentate Schiff base ligand, 2-((E)-(2-(E-5- bromo-2-hydroxybezenylideneamino) methyl)-4-bromophenol [H2L] was prepared by the reaction between of Cu (CH3COO)2·2H2O and (H2L) ligand with the ratio of 1:1, at the present of triethylamine by sonochemical method. The structure of [Cu (L)] complex was determined by FT-IR, UV-Vis, FESEM and molar conductivity. The structure of [Cu (L)] complex was characterized by single crystal X-ray diffraction. The geometry of [Cu (L)] complex was optimized using density functional theory (DFT) method with the B3LYP/6-31(d) level of theory. The calculated bond lengths and bond angles are in good agreement with the X-ray data. This complex was used as a novel precursor for preparing of CuO nano particles by the thermal decomposition method. The antibacterial activities of [H2L] ligand, nano-sized [Cu (L)] complex and nano-sized CuO have been screened against various strains of bacteria. According to the results, nano-sized CuO can be considered as an appropriate antibiotic agent.

  2. Synthesis,Crystal Structure and Reducibility of K2NiF4 Type Oxides Sm2—xSrxCuO4

    Institute of Scientific and Technical Information of China (English)

    ZHU,Ying-Hong; LOU,Hui; 等

    2002-01-01

    K2NiF4 type compounds Sm2-xSrxCuO4(0≤x≤1.2)were prepared.Rietveld refinement of powder diffraction data shows that the crystal system of these compounds belongs to T′ type tetragonal structure of space group I4/mmm,and the addition of Sr causes a dramatic shift of the O(I) ions along the c axis from Sm(Sr) toward Cu while scarcely affecting the Cu-O(Ⅱ)bond in basal CuO4 phane.From XRD data,it can be seen that when 0.0≤x≤0.6,Sm2-xSrxCuO4 belongs to a singlephase K2NiF4 type structure,while at x≥0.7,both the free SrO phase and the CuO phase exist in these compounds.From the results of XPS and rietveld refinement,it can be seen that after replacing Sm3+ with Sr2+ of lower valence,the valence of Cu and Sm does not change apparently,and thus some defect must be formed at the oxygen ion positions and/or position A on A2BO4 to keep charge balance and to stabilize the structure.

  3. Liquid Crystals

    Science.gov (United States)

    1990-01-01

    Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.

  4. Preparation of Mixed Perovskite Oxides for Blue-Green Lasers

    Science.gov (United States)

    1984-02-01

    higher for oxide or fluoride . 𔃽. A high radiative lifetime and high fluorescent quantum yield for Ce or the rare earth are desirable. 3 + 4...for all of our single crystal -4- preparations are lanthanum oxide (La„0 ), aluminum oxide (Al^O^) , scandium oxide (Sc„0-.) , and cerium oxide (Ce...crystal material is highly important. Ideally, oxides should be grown in O2, fluorides in ?„, and so forth in order to prevent defects such as

  5. Stripping scattering of fast atoms on surfaces of metal-oxide crystals and ultrathin films; Streifende Streuung schneller Atome an Oberflaechen von Metalloxid-Kristallen und ultraduennen Filmen

    Energy Technology Data Exchange (ETDEWEB)

    Blauth, David

    2010-03-11

    In the framework of the present dissertation the interactions of fast atoms with surfaces of bulk oxides, metals and thin films on metals were studied. The experiments were performed in the regime of grazing incidence of atoms with energies of some keV. The advantage of this scattering geometry is the high surface sensibility and thus the possibility to determine the crystallographic and electronic characteristics of the topmost surface layer. In addition to these experiments, the energy loss and the electron emission induced by scattered projectiles was investigated. The energy for electron emission and exciton excitation on Alumina/NiAl(110) and SiO{sub 2}/Mo(112) are determined. By detection of the number of projectile induced emitted electrons as function of azimuthal angle for the rotation of the target surface, the geometrical structure of atoms forming the topmost layer of different adsorbate films on metal surfaces where determined via ion beam triangulation. (orig.)

  6. Photonic crystals

    CERN Document Server

    Busch, Kurt; Wehrspohn, Ralf B; Föll, Helmut

    2006-01-01

    The majority of the contributions in this topically edited book stems from the priority program SPP 1113 ""Photonische Kristalle"" run by the Deutsche Forschungsgemeinschaft (DFG), resulting in a survey of the current state of photonic crystal research in Germany. The first part of the book describes methods for the theoretical analysis of their optical properties as well as the results. The main part is dedicated to the fabrication, characterization and modeling of two- and three-dimensional photonic crystals, while the final section presents a wide spectrum of applications: gas sensors, micr

  7. Iron Oxide with Different Crystal Phases (α- and γ-Fe2O3) in Electroanalysis and Ultrasensitive and Selective Detection of Lead(II): An Advancing Approach Using XPS and EXAFS.

    Science.gov (United States)

    Li, Shan-Shan; Li, Wen-Juan; Jiang, Tian-Jia; Liu, Zhong-Gang; Chen, Xing; Cong, Huai-Ping; Liu, Jin-Huai; Huang, Yu-Ying; Li, Li-Na; Huang, Xing-Jiu

    2016-01-01

    Iron oxide with different crystal phases (α- and γ-Fe2O3) has been applied to electrode coatings and been demonstrated to ultrasensitive and selective electrochemical sensing toward heavy metal ions (e.g., Pb(II)). A range of Pb(II) contents in micromoles (0.1 to 1.0 μM) at α-Fe2O3 nanoflowers with a sensitivity of 137.23 μA μM(-1) cm(-2) and nanomoles (from 0.1 to 1.0 nM) at γ-Fe2O3 nanoflowers with a sensitivity of 197.82 μA nM(-1) cm(-2) have been investigated. Furthermore, an extended X-ray absorption fine structure (EXAFS) technique was applied to characterize the difference of local structural environment of the adsorbed Pb(II) on the surface of α- and γ-Fe2O3. The results first showed that α- and γ-Fe2O3 had diverse interaction between Pb(II) and iron (hydro)oxides, which were consistent with the difference of electrochemical performance. Determining the responses of Cu(II) and Hg(II) as the most appropriate choice for comparison, the stripping voltammetric quantification of Pb(II) with high sensitivity and selectivity at γ-Fe2O3 nanoflower has been demonstrated. This work reveals that the stripping performances of a nanomodifier have to be directly connected with its intrinsic surface atom arrangement.

  8. 21 CFR 186.1300 - Ferric oxide.

    Science.gov (United States)

    2010-04-01

    ... iron hydroxide oxide. The product is red-brown to black trigonal crystals. (b) In accordance with § 186... Substances Affirmed as GRAS § 186.1300 Ferric oxide. (a) Ferric oxide (iron (III) oxide, Fe2O3, CAS Reg....

  9. Ribbon Crystals

    DEFF Research Database (Denmark)

    Bohr, Jakob; Markvorsen, Steen

    2013-01-01

    A repetitive crystal-like pattern is spontaneously formed upon the twisting of straight ribbons. The pattern is akin to a tessellation with isosceles triangles, and it can easily be demonstrated with ribbons cut from an overhead transparency. We give a general description of developable ribbons...

  10. Therapeutic Crystals

    Science.gov (United States)

    Bond, Charles S.

    2014-01-01

    Some readers might not fully know what the difference is between crystallography, and the "new age" practice of dangling crystals around the body to capitalise on their healing energy. The latter is often considered to be superstition, while ironically, the former has actually resulted in real rationally-based healing of human diseases…

  11. Crystal growth of pure and impurity-doped lead chloride single crystals from the melt

    NARCIS (Netherlands)

    Willemsen, B.

    An account is given of the purification and the crystal growing of lead chloride. Difficulties observed are blackening of the material and the formation of oxides. It is evident that oxygen should be avoided. The influence of water vapour is studied with mass spectroscopy, crystal microbalance

  12. Crystal growth of pure and impurity-doped lead chloride single crystals from the melt

    NARCIS (Netherlands)

    Willemsen, B.

    1971-01-01

    An account is given of the purification and the crystal growing of lead chloride. Difficulties observed are blackening of the material and the formation of oxides. It is evident that oxygen should be avoided. The influence of water vapour is studied with mass spectroscopy, crystal microbalance measu

  13. Crystal structure of an ethylene sorption complex of fully vacuum-dehydrated fully Ag+-exchanged zeolite X (FAU). Silver atoms have reduced ethylene to give CH2 2- carbanions at framework oxide vacancies.

    Science.gov (United States)

    Lee, Young Mi; Choi, Seo Jung; Kim, Yang; Seff, Karl

    2005-11-03

    The crystal structure of an ethylene sorption complex of fully vacuum-dehydrated fully Ag(+)-exchanged zeolite X (FAU), a = 24.865(2) A, has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd at 21 degrees C. It is very different from the ethylene complex of Ag(92)-X that had been dehydrated at 400 degrees C in flowing oxygen, as were the two dehydrated structures. The crystal was prepared by ion exchange in a flowing stream of aqueous 0.05 M AgNO(3) for 3 days, followed by dehydration at 400 degrees C and 2 x 10(-6) Torr for 2 days, followed by exposure to 300 Torr of zeolitically dry ethylene gas for 2 h at 21 degrees C. The structure was determined in this atmosphere and was refined using all data to the final error indices (based upon the 534 reflections for which F(o) > 4sigma(F(o))) R(1) = 0.062 and wR(2) = 0.135. In this structure, per unit cell, 14 Ag(+) ions were found at the octahedral site I (Ag-O = 2.611(9) A), and 32 partially reduced Ag(+) ions fill two different site I' positions deep in the sodalite cavities (Ag-O = 2.601(13) and 2.618(12) A). The sodalite cavities host two different cationic silver clusters. In about 47% of sodalite units, eight silver atoms form interpenetrating tetrahedra, Ag(8)(n+) (n = 4 is suggested), with T(d)() symmetry. The other 53% of the sodalite units host cyclo-Ag(4)(m+) (m = 2 is suggested) cations with near S(4) symmetry. These clusters are very similar to those in vacuum-dehydrated Ag(92)-X. Thirty-two Ag(+) ions fill the single 6-rings, 15 at site II' (Ag-O = 2.492(10) A), and 17 at site II (Ag-O = 2.460(9) A). The latter 17 lie in supercages where each forms a lateral pi-complex with an ethylene molecule. In turn, each C(2)H(4) molecule forms two cis electrostatic hydrogen bonds to framework oxygens. The remaining 14 Ag+ ions occupy three different II' sites. Vacuum dehydration had caused substantial decomposition: per unit cell, 30 of the 92 Ag(+) ions were reduced and 15

  14. Photonic crystals principles and applications

    CERN Document Server

    Gong, Qihuang

    2013-01-01

    IntroductionPrimary Properties of Photonic CrystalsFabrication of Photonic CrystalsPhotonic Crystal All-Optical SwitchingTunable Photonic Crystal FilterPhotonic Crystal LaserPhotonic Crystal Logic DevicesPhotonic Crystal Sensors

  15. Phase equilibria, crystal structure and properties of complex oxides in the Nd2O3-SrO-CoO system

    Science.gov (United States)

    Aksenova, T. V.; Efimova, T. G.; Lebedev, O. I.; Elkalashy, Sh. I.; Urusova, A. S.; Cherepanov, V. A.

    2017-04-01

    The phase equilibria in the ½Nd2O3-SrO-CoO system were systematically studied at 1373 K in air. The intermediate phases formed in the ½Nd2O3-SrO-CoO system at 1373 K in air are: Nd1-xSrxCoO3-δ (0.0≤x≤0.5 with orthorhombic structure, sp. gr. Pbnm and 0.6≤x≤0.95 whose structure was detected as cubic according to XRD sp. gr. Pm3m, but shown to be tetragonal by TEM due to the oxygen vacancy ordering), Nd2-ySryCoO4-δ (0.6≤y≤1.1 with tetragonal K2NiF4-type structure, sp. gr. I4/mmm) and Nd2-zSrzO3 (0.0≤z≤0.15 with hexagonal structure, sp. gr. P-3m1). The unit cell parameters for the single phase samples were refined by the Rietveld analysis. The changes of oxygen content in Nd1-xSrxCoO3-δ (0.6≤x≤0.95) and Ruddlesden-Popper oxide Nd2-ySryCoO4-δ were examined by TGA. All were found to be oxygen deficient phases. High-temperature dilatometry allows calculating the thermal expansion coefficient and evaluating the chemical expansion coefficient at high temperature. The projection of isothermal-isobaric phase diagram for the Nd-Sr-Co-O system at 1373 K in air to the compositional triangle of metallic components has been constructed. The phase equilibria in the studied Nd-Sr-Co-O system were compared to La-Sr-Co-O and Nd-M-Co-O (M=Ca and Ba).

  16. Copper-Dioxygen Complex Mediated C-H Bond Oxygenation: Relevance for Particulate Methane Monooxygenase (pMMO)

    OpenAIRE

    Himes, Richard A.; Karlin, Kenneth D.

    2009-01-01

    Particulate methane monooxygenase (pMMO), an integral membrane protein found in methanotrophic bacteria, catalyzes the oxidation of methane to methanol. Expression and greater activity of the enzyme in the presence of copper ion suggest that pMMO is a cuprous metalloenzyme. Recent advances – especially the first crystal structures of pMMO – have energized the field, but the nature of the active site(s) and the mechanism of methane oxidation remain poorly understood – yet hotly contested. Here...

  17. Biological Macromolecule Crystallization Database

    Science.gov (United States)

    SRD 21 Biological Macromolecule Crystallization Database (Web, free access)   The Biological Macromolecule Crystallization Database and NASA Archive for Protein Crystal Growth Data (BMCD) contains the conditions reported for the crystallization of proteins and nucleic acids used in X-ray structure determinations and archives the results of microgravity macromolecule crystallization studies.

  18. Effects of sputtering power on properties of copper oxides thin films deposited on glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ooi, P. K.; Ng, S. S.; Abdullah, M. J. [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2015-04-24

    Copper oxides are deposited by radio frequency sputtering using copper target in the mixture of argon and oxygen gasses. The structural and optical properties of the copper oxides deposited at different sputtering powers have been investigated. All the films are single phase polycrystalline. At low RF power (100 W), the film is monoclinic structure of cupric oxide (CuO). Meanwhile, the films are cubic structure of cuprous oxide (Cu2O) at higher RF power. Field emission scanning electron microscopy images show the films have different morphologies with small grain size and consist of a lot of voids. The analysis of energy dispersive X-ray spectroscopy shows that the ratio of Cu to O is increased as the RF power increased. From the ultraviolet–visible spectroscopy, the films have a broad absorption edge in the range of 300–500 nm. The band gap of the films grown at RF power of 100 W, and 120 W and above, were 1.18 eV and 2.16 eV, respectively.

  19. Nanoparticular metal oxide/anatase catalysts

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention concerns a method of preparation of nanoparticular metal oxide catalysts having a narrow particle size distribution. In particular, the invention concerns preparation of nanoparticular metal oxide catalyst precursors comprising combustible crystallization seeds upon which...... the catalyst metai oxide is co-precipitated with the carrier metal oxide, which crystallization seeds are removed by combustion in a final calcining step. The present invention also concerns processes wherein the nanoparticular metal oxide catalysts of the invention are used, such as SCR (deNOx) reactions...

  20. Crystal fields of porphyrins and phthalocyanines

    Science.gov (United States)

    Johnson, P. S.; Boukahil, I.; Himpsel, F. J.; Kennedy, C.; Jersett, N.; Cook, P. L.; Garcia-Lastra, J. M.

    2014-03-01

    Polarization-dependent X-ray absorption spectroscopy at the N 1s and metal 2p edges is combined with density functional and atomic multiplet calculations to determine the crystal field parameters 10Dq, Ds, and Dt of transition metal (Mn, Fe, Co, Ni) phthalocyanines and octaethylporphyrins. Octaethyl porphyrins are observed to lie flat on Si with native oxide, while phthalocyanines lie on edge. Strong polarization dependence is found at all edges, which facilitates a unique determination of the crystal field parameters. Crystal field values from PBE density functional calculations provide helpful starting values, which are refined by fitting atomic multiplet calculations to the data. Since the crystal field affects electron-hole separation in solar cells, the systematic set of crystal field parameters obtained here can be useful for optimizing dyes for solar cells.

  1. INVESTIGATION OF BONDING IN OXIDE-FIBER (WHISKER) REINFORCED METALS.

    Science.gov (United States)

    CERAMIC FIBERS , BONDING), (*COMPOSITE MATERIALS, BONDING), (*BONDING, CERAMIC FIBERS ), ALUMINUM COMPOUNDS, OXIDES, ZIRCONIUM, NICKEL, TITANIUM, CHROMIUM, SINGLE CRYSTALS, VACUUM, SHEAR STRESSES, SURFACE PROPERTIES, ADDITIVES.

  2. CCDC 1410820: Experimental Crystal Structure Determination : heptakis(dimethylammonium) heptacosa-terbium dodecakis((1,1'-biphenyl)-3,4',5-tricarboxylate) hexakis(2-fluorobenzoate) hexakis(formate) hexatriacontakis(hydroxide) bis(oxide) unknown solvate hydrate

    KAUST Repository

    Alezi, Dalal

    2015-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  3. Ribbon crystals.

    Directory of Open Access Journals (Sweden)

    Jakob Bohr

    Full Text Available A repetitive crystal-like pattern is spontaneously formed upon the twisting of straight ribbons. The pattern is akin to a tessellation with isosceles triangles, and it can easily be demonstrated with ribbons cut from an overhead transparency. We give a general description of developable ribbons using a ruled procedure where ribbons are uniquely described by two generating functions. This construction defines a differentiable frame, the ribbon frame, which does not have singular points, whereby we avoid the shortcomings of the Frenet-Serret frame. The observed spontaneous pattern is modeled using planar triangles and cylindrical arcs, and the ribbon structure is shown to arise from a maximization of the end-to-end length of the ribbon, i.e. from an optimal use of ribbon length. The phenomenon is discussed in the perspectives of incompatible intrinsic geometries and of the emergence of long-range order.

  4. Crystallization process

    Science.gov (United States)

    Adler, Robert J.; Brown, William R.; Auyang, Lun; Liu, Yin-Chang; Cook, W. Jeffrey

    1986-01-01

    An improved crystallization process is disclosed for separating a crystallizable material and an excluded material which is at least partially excluded from the solid phase of the crystallizable material obtained upon freezing a liquid phase of the materials. The solid phase is more dense than the liquid phase, and it is separated therefrom by relative movement with the formation of a packed bed of solid phase. The packed bed is continuously formed adjacent its lower end and passed from the liquid phase into a countercurrent flow of backwash liquid. The packed bed extends through the level of the backwash liquid to provide a drained bed of solid phase adjacent its upper end which is melted by a condensing vapor.

  5. Thermodynamic reactivity, growth and characterization of mercurous halide crystals

    Science.gov (United States)

    Singh, N. B.; Gottlieb, M.; Henningsen, T.; Hopkins, R. H.; Mazelsky, R.; Singh, M.; Glicksman, M. E.; Paradies, C.

    1992-01-01

    Thermodynamic calculations were carried out for the Hg-X-O system (X = Cl, Br, I) to identify the potential sources of contamination and relative stability of oxides and oxy-halide phases. The effect of excess mercury vapor pressure on the optical quality of mercurous halide crystal was studied by growing several mercurous chloride crystals from mercury-rich composition. The optical quality of crystals was examined by birefringence interferometry and laser scattering studies. Crystals grown in slightly mercury-rich composition showed improved optical quality relative to stoichiometric crystals.

  6. Two different zinc(II)-aqua complexes held up by a metal-oxide based support: Synthesis, crystal structure and catalytic activity of [HMTAH]2[{Zn(H2O)5}{Zn(H2O)4}{Mo7O24}].2H2O (HMTAH = protonated hexamethylenetetramine)

    Indian Academy of Sciences (India)

    T Arumuganathan; A Srinivasarao; T Vijay Kumar; Samar K Das

    2008-01-01

    An inorganic−organic hybrid material, [HMTAH]2[{Zn(H2O)5}{Zn(H2O)4}{Mo7O24}].2H2O (1) (where HMTAH = protonated hxamethylenetetramine) has been synthesized and structurally characterized. The compound 1 crystallizes in a monoclinic space group 2/. The crystal data of 1: = 43.12(3), = 12.399(10), = 16.285(13), = 111.131(11), = 8. Its crystal structure shows that two different Zn(II)-aqua complexes, [Zn(H2O)5]2+ and [Zn(H2O)4]2+ are covalently coordinated to a heptamolybdateanion [Mo7O24]6- resulting in an anionic species of polyoxometalate supported zinc-aqua complexes, [{Zn(H2O)}{Zn(H2O)4}{Mo7O24}]2-, that is stabilized with two protonated hexamethylenetetramine cations in the title compound 1. In the crystal structure, both lattice water molecules are found to interact with the heptamolybdate cluster anion and the protonated hexamethylenetetramine cation resulting in an intricate three-dimensional hydrogen bonding network. Interestingly, compound 1 exhibits catalytic activity towards oxidation of some primary alcohols.

  7. Bubble formation in oxide scales on SiC

    Science.gov (United States)

    Mieskowski, D. M.; Mitchell, T. E.; Heuer, A. H.

    1984-01-01

    The oxidation of alpha-SiC single crystals and sintered alphaand beta-SiC polycrystals has been investigated at elevated temperatures. Bubble formation is commonly observed in oxide scales on polycrystalline SiC, but is rarely found on single-crystal scales; bubbles result from the preferential oxidation of C inclusions, which are abundant in SiC polycrystals. The absence of bubbles on single crystals, in fact, implies that diffusion of the gaseous species formed on oxidation, CO (or possibly SiO), controls the rate of oxidation of SiC.

  8. Bubble formation in oxide scales on SiC

    Science.gov (United States)

    Mieskowski, D. M.; Mitchell, T. E.; Heuer, A. H.

    1984-01-01

    The oxidation of alpha-SiC single crystals and sintered alphaand beta-SiC polycrystals has been investigated at elevated temperatures. Bubble formation is commonly observed in oxide scales on polycrystalline SiC, but is rarely found on single-crystal scales; bubbles result from the preferential oxidation of C inclusions, which are abundant in SiC polycrystals. The absence of bubbles on single crystals, in fact, implies that diffusion of the gaseous species formed on oxidation, CO (or possibly SiO), controls the rate of oxidation of SiC.

  9. Methodology of Single Crystal Growth and Microstructure Analysis of CoTi(Zr) Intermetallic Compounds

    Institute of Scientific and Technical Information of China (English)

    Lijuan ZHANG; Mike L.JENKINS; Glyn TAYLOR

    2005-01-01

    The effects of preparation and crystal growth methods on the microstructure, composition, and oxidation of CoTi(Zr)intermetallics were dealt with. A group of methods has been used to produce CoTi and CoTi(Zr) crystals to prevent the formation of titanium oxide particles during melting and crystal growth. The results show that more oxides formed when using powdered starting materials even though the metals handled were and melted under an inert gas atmosphere; using bulk starting materials produced alloys showed less oxidation than powders, but adding a small amount of Al to getter the oxygen was not sufficient to prevent TiO2 formation. However, using a slightly reducing atmosphere during initial melting was highly effective in reducing the formation of oxide. Crystal growth carried out in Ar did not reduce the amount of oxide but only redistributed the particles. TiO2 particles were found only inthe grain boundaries after crystal growing, where they obstructed grain growth. Crystal growth in a vacuum was found to be essential in producing oxide free crystals. A seed selection technique was developed and used in growing CoTi single crystals. The microstructures of the samples were determined using optical microscopy, scanning electron microscopy and transmission electron microscopy, including the morphologies, grain sizes, oxide distributions and crystal structure confirmation.

  10. The contrasting effect of the Ta/Nb ratio in (111)-layered B-site deficient hexagonal perovskite Ba5Nb4-xTaxO15 crystals on visible-light-induced photocatalytic water oxidation activity of their oxynitride derivatives.

    Science.gov (United States)

    Hojamberdiev, Mirabbos; Bekheet, Maged F; Zahedi, Ehsan; Wagata, Hajime; Vequizo, Junie Jhon M; Yamakata, Akira; Yubuta, Kunio; Gurlo, Aleksander; Domen, Kazunari; Teshima, Katsuya

    2016-08-02

    The effect of the Ta/Nb ratio in the (111)-layered B-site deficient hexagonal perovskite Ba5Nb4-xTaxO15 (0 ≤ x ≤ 4) crystals grown by a KCl flux method on visible-light-induced photocatalytic water oxidation activity of their oxynitride derivatives BaNb1-xTaxO2N (0 ≤ x ≤ 1) was investigated. The Rietveld refinement of X-ray data revealed that all Ba5Nb4-xTaxO15 samples were well crystallized in the space group P3[combining macron]m1 (no. 164). Phase-pure BaNb1-xTaxO2N (0 ≤ x ≤ 1) porous structures were obtained by nitridation of the flux-grown oxide crystals at 950 °C for 20, 25, 30, 35, and 40 h, respectively. The absorption edge of BaNb1-xTaxO2N (0 ≤ x ≤ 1) was slightly shifted from 720 to 690 nm with the increasing Ta/Nb ratio. The O2 evolution rate gradually progressed and reached the highest value (127.24 μmol in the first 2 h) with the Ta content up to 50 mol% but decreased at 75 and 100 mol% presumably due to the reduced specific surface area and high density of structural defects, such as grain boundaries acting as recombination centers, originated from high-temperature nitridation for prolonged periods. Transient absorption spectroscopy provided evidence for the effect of the Ta/Nb ratio on the behavior and energy states of photogenerated charge carriers, indicating a direct correlation with photocatalytic water oxidation activity of BaNb1-xTaxO2N.

  11. Oxidation behavior of Cu nanoparticles embedded into semiconductive TiO{sub 2} matrix

    Energy Technology Data Exchange (ETDEWEB)

    Stranak, Vitezslav, E-mail: stranak@prf.jcu.cz [University of South Bohemia, Faculty of Science, Branisovska 31, 37005 Ceske Budejovice (Czech Republic); Drache, Steffen; Wulff, Harm [University of Greifswald, Institute of Physics, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany); Hubicka, Zdenek [Institute of Physics, Academy of Science of the Czech Republic, Na Slovance 2, 18221 Prague (Czech Republic); Tichy, Milan [Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, 18000 Prague (Czech Republic); Kruth, Angela [Leibniz Institute for Plasma Science and Technology, INP Greifswald e.V., Felix-Hausdorff-Straße 2, 17489 Greifswald (Germany); Helm, Christiane A.; Hippler, Rainer [University of Greifswald, Institute of Physics, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany)

    2015-08-31

    Metal nanoparticles embedded into a semiconductive matrix represent a promising material for widely sought advanced technological applications. We focused our interest on the preparation of TiO{sub 2} matrix with embedded Cu nanoparticles. In particular, we studied the effect of reactive discharge (Ar/O{sub 2}) exposition on copper oxidation, which can result in two stable forms: cuprous oxide (Cu{sub 2}O) and cupric oxide (CuO). Copper nanoparticles, of size in range 10–50 nm, were produced by magnetron sputtering in combination with gas aggregation. The beam of Cu nanoparticles was impinging onto a silicon substrate which was directly exposed to a reactive Ar/O{sub 2} magnetron discharge providing sputtering of Ti target at the same time. The properties of deposited nanocomposite Cu({sub x}O)–TiO{sub 2} were investigated by X-ray photoelectron spectroscopy, grazing incidence X-ray diffractometry, X-ray reflectometry and scanning electron microscopy techniques to reveal the nanocomposite properties and to understand the oxidation process of embedded Cu nanoparticles. It was found that CuO is preferentially formed if copper is exposed to active oxygen species (O{sup +}, O{sup −}, O{sup ⁎} etc.) produced in the reactive magnetron discharge. On the other hand, Cu{sub 2}O was observed in the case of copper reaction in ambient Ar/O{sub 2} atmosphere. As a result, two possible copper oxidation mechanisms are proposed, employing chemical kinetics. - Highlights: • Cu–TiO{sub 2} nanocomposite was prepared by plasma assisted methods. • Embedded Cu always occurs in oxidized phase depending on the way of oxidation. • CuO is formed if copper is exposed to active oxygen species produced in Ar/O{sub 2} discharge. • Cu{sub 2}O appears in the case of copper reaction in an ambient oxygen-based atmosphere. • Two possible copper oxidation mechanisms are proposed.

  12. Oxygen Luminescence Centers in LiF-MeO Crystals

    Science.gov (United States)

    Lisitsyna, L. A.; Suleimen, R. N.

    2017-08-01

    Spectral-kinetic parameters of luminescence of LiF crystals doped with various polyvalent metal oxides (Li, Ti, Fe, W, U) were studied in the temperature range of 100-300 K and the absorbed doses range of 0-105 Gy. A model for describing polyvalent activation cation role in the processes of radiation energy dissipation in the crystal volume is suggested.

  13. Titanium-iridium oxide layer coating to suppress photocorrosion during photocatalytic water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Yongwoo; Lee, Hyunjoo [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kwon, Yongwoo; Lee, Hyunjoo [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2015-12-15

    Photocatalysts with a small band gap energy have received a great deal of interest due their high solar conversion efficiencies. Cuprous oxide (Cu{sub 2}O) has attracted attention because of its small bandgap energy, a direct bandgap structure, its suitable band structure for water splitting, high absorption coefficient, non-toxicity, and its large abundance. However, it has poor stability due to the fickle oxidation states of copper. To enhance the stability and the production rate of hydrogen and oxygen, a TiIrOX overlayer was successfully formed on the Cu{sub 2}O under various synthesis conditions. The composition and oxidation state of the Ir species in the overlayer were optimized through the control of the Ir precursor and the amount of water. The Ir/Ti precursor molar ratio was linearly related to the surface Ir/Ti molar ratio. The addition of water converted the Ir precursor to IrO{sub 2}. The thickness of the overlayer was controlled by differing the synthesis times of the coating. Then, the largest amounts of hydrogen and oxygen were produced through the optimization of the TiIrOX overlayer with a higher IrO{sub 2} fraction and a thicker overlayer.

  14. Binary colloidal crystals

    NARCIS (Netherlands)

    Christova-Zdravkova, C.G.

    2005-01-01

    Binary crystals are crystals composed of two types of particles having different properties like size, mass density, charge etc. In this thesis several new approaches to make binary crystals of colloidal particles that differ in size, material and charge are reported We found a variety of crystal st

  15. Semiconductor monolayer assemblies with oriented crystal faces

    KAUST Repository

    Ma, Guijun

    2012-01-01

    Fabrication of two-dimensional monolayers of crystalline oxide and oxynitride particles was attempted on glass plate substrates. X-Ray diffraction patterns of the assemblies show only specific crystal facets, indicative of the uniform orientation of the particles on the substrate. The selectivity afforded by this immobilization technique enables the organization of randomly distributed polycrystalline powders in a controlled manner.

  16. Mixed crystal organic scintillators

    Science.gov (United States)

    Zaitseva, Natalia P; Carman, M Leslie; Glenn, Andrew M; Hamel, Sebastien; Hatarik, Robert; Payne, Stephen A; Stoeffl, Wolfgang

    2014-09-16

    A mixed organic crystal according to one embodiment includes a single mixed crystal having two compounds with different bandgap energies, the organic crystal having a physical property of exhibiting a signal response signature for neutrons from a radioactive source, wherein the signal response signature does not include a significantly-delayed luminescence characteristic of neutrons interacting with the organic crystal relative to a luminescence characteristic of gamma rays interacting with the organic crystal. According to one embodiment, an organic crystal includes bibenzyl and stilbene or a stilbene derivative, the organic crystal having a physical property of exhibiting a signal response signature for neutrons from a radioactive source.

  17. Pressure cryocooling protein crystals

    Science.gov (United States)

    Kim, Chae Un; Gruner, Sol M.

    2011-10-04

    Preparation of cryocooled protein crystal is provided by use of helium pressurizing and cryocooling to obtain cryocooled protein crystal allowing collection of high resolution data and by heavier noble gas (krypton or xenon) binding followed by helium pressurizing and cryocooling to obtain cryocooled protein crystal for collection of high resolution data and SAD phasing simultaneously. The helium pressurizing is carried out on crystal coated to prevent dehydration or on crystal grown in aqueous solution in a capillary.

  18. Interaction of a pseudo-π C—C bond with cuprous and argentous chlorides: Cyclopropane⋯CuCl and cyclopropane⋯AgCl investigated by rotational spectroscopy and ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Zaleski, Daniel P.; Mullaney, John C.; Bittner, Dror M.; Walker, Nicholas R., E-mail: a.c.legon@bristol.ac.uk, E-mail: nick.walker@newcastle.ac.uk [School of Chemistry, Newcastle University, Bedson Building, Newcastle-Upon-Tyne NE1 7RU (United Kingdom); Tew, David P.; Legon, Anthony C., E-mail: a.c.legon@bristol.ac.uk, E-mail: nick.walker@newcastle.ac.uk [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom)

    2015-10-28

    Strongly bound complexes (CH{sub 2}){sub 3}⋯MCl (M = Cu or Ag), formed by non-covalent interaction of cyclopropane and either cuprous chloride or argentous chloride, have been generated in the gas phase by means of the laser ablation of either copper or silver metal in the presence of supersonically expanded pulses of a gas mixture containing small amounts of cyclopropane and carbon tetrachloride in a large excess of argon. The rotational spectra of the complexes so formed were detected with a chirped-pulse, Fourier transform microwave spectrometer and analysed to give rotational constants and Cu and Cl nuclear quadrupole coupling constants for eight isotopologues of each of (CH{sub 2}){sub 3}⋯CuCl and (CH{sub 2}){sub 3}⋯AgCl. The geometry of each of these complexes was established unambiguously to have C{sub 2v} symmetry, with the three C atoms coplanar, and with the MCl molecule lying along a median of the cyclopropane C{sub 3} triangle. This median coincides with the principal inertia axis a in each of the two complexes (CH{sub 2}){sub 3}⋯MCl. The M atom interacts with the pseudo-π bond linking the pair of equivalent carbon atoms {sup F}C (F = front) nearest to it, so that M forms a non-covalent bond to one C—C edge of the cyclopropane molecule. The (CH{sub 2}){sub 3}⋯MCl complexes have similar angular geometries to those of the hydrogen- and halogen-bonded analogues (CH{sub 2}){sub 3}⋯HCl and (CH{sub 2}){sub 3}⋯ClF, respectively. Quantitative details of the geometries were determined by interpretation of the observed rotational constants and gave results in good agreement with those from ab initio calculations carried out at the CCSD(T)(F12*)/aug-cc-pVTZ-F12 level of theory. Interesting geometrical features are the lengthening of the {sup F}C—{sup F}C bond and the shrinkage of the two equivalent {sup B}C—{sup F}C (B = back) bonds relative to the C—C bond in cyclopropane itself. The expansions of the {sup F}C—{sup F}C bond are 0

  19. Facile synthesis of flower like copper oxide and their application to hydrogen peroxide and nitrite sensing

    Directory of Open Access Journals (Sweden)

    Zhang Li

    2011-12-01

    Full Text Available Abstract Background The detection of hydrogen peroxide (H2O2 and nitrite ion (NO2- is of great important in various fields including clinic, food, pharmaceutical and environmental analyses. Compared with many methods that have been developed for the determination of them, the electrochemical detection method has attracted much attention. In recent years, with the development of nanotechnology, many kinds of micro/nano-scale materials have been used in the construction of electrochemical biosensors because of their unique and particular properties. Among these catalysts, copper oxide (CuO, as a well known p-type semiconductor, has gained increasing attention not only for its unique properties but also for its applications in many fields such as gas sensors, photocatalyst and electrochemistry sensors. Continuing our previous investigations on transition-metal oxide including cuprous oxide and α-Fe2O3 modified electrode, in the present paper we examine the electrochemical and electrocatalytical behavior of flower like copper oxide modified glass carbon electrodes (CuO/GCE. Results Flower like copper oxide (CuO composed of many nanoflake was synthesized by a simple hydrothermal reaction and characterized using field-emission scanning electron microscopy (FE-SEM and X-ray diffraction (XRD. CuO modified glass carbon electrode (CuO/GCE was fabricated and characterized electrochemically. A highly sensitive method for the rapid amperometric detection of hydrogen peroxide (H2O2 and nitrite (NO2- was reported. Conclusions Due to the large specific surface area and inner characteristic of the flower like CuO, the resulting electrode show excellent electrocatalytic reduction for H2O2 and oxidation of NO2-. Its sensitivity, low detection limit, fast response time and simplicity are satisfactory. Furthermore, this synthetic approach can also be applied for the synthesis of other inorganic oxides with improved performances and they can also be extended to

  20. Composition dependence of spontaneous crystallization of phosphosilicate glass melts during cooling

    DEFF Research Database (Denmark)

    Liu, S.J.; Zhu, C.F.; Zhang, Y.F.

    2012-01-01

    Crystallization behavior of alumino-phospho-silicate melts during cooling is studied by means of the differential scanning calorimetry, X-ray diffractometry and viscometry. The results show a pronounced impact of alkaline earth oxide, alkali oxide and fluoride on the crystal type...

  1. Tris(3-aminophenylphosphine oxide ethanol solvate

    Directory of Open Access Journals (Sweden)

    Jun Han

    2009-04-01

    Full Text Available The title compound crystallized as an ethanol solvate, C18H18N3OP·C2H6O. It is the reduction product of tris(3-nitrophenylphosphine oxide. In the crystal, there are intermolecular N—H...O hydrogen bonds between neighbouring tris(3-aminophenylphosphine oxide molecules and O—H...O hydrogen bonds involving the ethanol solvent molecule.

  2. Crystalline mesoporous metal oxide

    Institute of Scientific and Technical Information of China (English)

    Wenbo Yue; Wuzong Zhou

    2008-01-01

    Since the discovery of many types of mesoporous silicas, such as SBA-15, KIT-6, FDU-12 and SBA-16, porous crystalline transition metal oxides, such as Cr2O3, Co3O4, In2O3, NiO, CeO2, WO3, Fe2O3 and MnO2, have been synthesized using the mesoporous silicas as hard templates. Several synthetic methods have been developed. These new porous materials have high potential applications in catalysis, Li-ion rechargeable batteries and gas sensors. This article gives a brief review of the research of porous crystals of metal oxides in the last four years.

  3. An investigation of the effects of CeO2 crystal planes on the aerobic oxidative synthesis of imines from alcohols and amines%纳米二氧化铈催化制备亚胺

    Institute of Scientific and Technical Information of China (English)

    张志鑫; 王业红; 王敏; 吕建民; 李利花; 张哲; 李名润; 蒋景阳; 王峰

    2015-01-01

    化合物的转化率可达89%以上,亚胺类化合物的选择性可达90%以上.通过水热合成法分别制备了棒状CeO2、立方体CeO2和八面体CeO2,并通过X射线衍射、透射电子显微镜和高分辨透射电子显微镜确证了其结构和形貌,结果表明三种形貌的CeO2均为纯相的CeO2,其中棒状CeO2暴露(110)和(100)晶面,立方体CeO2暴露(100)晶面,八面体CeO2暴露(111)晶面.并以苯甲醇氧化反应和苯甲醇与苯胺反应为探针研究了其催化性能.结果发现:不同形貌的CeO2具有显著不同的催化活性,其中棒状CeO2表现出最优异的催化性能,立方体CeO2和八面体CeO2次之.通过Raman光谱表征了不同形貌CeO2的氧空位性质并比较了它们的氧空位浓度.结果发现:棒状CeO2的氧空位浓度相对值(A595/A462)为0.077,高于立方体CeO2和八面体CeO2.通过比较分析计算可知,在CeO2(110),(100)和(111)三种晶面中,(110)晶面因其具有最多的氧空位而表现出最高的催化活性和优异的氧化还原性质,(110)晶面上亚胺的生成速率为4.618 mmol/(g·h),分别为(100)晶面和(111)晶面上的32倍和49倍.该研究有助于提高认识CeO2基催化材料的低温氧化还原性质.%We herein report the effects of CeO2 crystal planes on the oxidative coupling of alcohols and amines to form imines. CeO2 exhibits significant catalytic activity under mild reaction conditions (60 °C) during the synthesis of 13 different imines, giving>89%conversions and>90%selectivities. The crystal planes of CeO2 greatly affect the catalytic performance. Among the crystal planes investigat-ed (the (110), (100) and (111) planes), the (110) plane shows the strongest redox ability and thus the best catalytic activity, generating a 97%yield of the imine at 60 °C in 2 h, because it contains the highest concentration of oxygen vacancies.

  4. Influence of thermal annealing on microstructural, morphological, optical properties and surface electronic structure of copper oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Akgul, Funda Aksoy, E-mail: fundaaksoy01@gmail.com [Department of Physics, Nigde University, 51240 Nigde (Turkey); Center for Solar Energy Research and Applications, Middle East Technical University, 06800 Ankara (Turkey); Akgul, Guvenc, E-mail: guvencakgul@gmail.com [Bor Vocational School, Nigde University, 51700 Nigde (Turkey); Center for Solar Energy Research and Applications, Middle East Technical University, 06800 Ankara (Turkey); Yildirim, Nurcan [Department of Physics Engineering, Ankara University, 06100 Ankara (Turkey); Department of Metallurgical and Materials Engineering, Middle East Technical University, 06800 Ankara (Turkey); Unalan, Husnu Emrah [Department of Metallurgical and Materials Engineering, Middle East Technical University, 06800 Ankara (Turkey); Center for Solar Energy Research and Applications, Middle East Technical University, 06800 Ankara (Turkey); Turan, Rasit [Department of Physics, Middle East Technical University, 06800 Ankara (Turkey); Center for Solar Energy Research and Applications, Middle East Technical University, 06800 Ankara (Turkey)

    2014-10-15

    In this study, effect of the post-deposition thermal annealing on copper oxide thin films has been systemically investigated. The copper oxide thin films were chemically deposited on glass substrates by spin-coating. Samples were annealed in air at atmospheric pressure and at different temperatures ranging from 200 to 600°C. The microstructural, morphological, optical properties and surface electronic structure of the thin films have been studied by diagnostic techniques such as X-ray diffraction (XRD), Raman spectroscopy, ultraviolet–visible (UV–VIS) absorption spectroscopy, field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The thickness of the films was about 520 nm. Crystallinity and grain size was found to improve with annealing temperature. The optical bandgap of the samples was found to be in between 1.93 and 2.08 eV. Cupric oxide (CuO), cuprous oxide (Cu{sub 2}O) and copper hydroxide (Cu(OH){sub 2}) phases were observed on the surface of as-deposited and 600 °C annealed thin films and relative concentrations of these three phases were found to depend on annealing temperature. A complete characterization reported herein allowed us to better understand the surface properties of copper oxide thin films which could then be used as active layers in optoelectronic devices such as solar cells and photodetectors. - Highlights: • Effect of post-deposition annealing on copper oxide thin films was investigated. • Structural, optical, and electronic properties of the thin films were determined. • Oxidation states of copper oxide thin films were confirmed by XPS analysis. • Mixed phases of CuO and Cu{sub 2}O were found to coexist in copper oxide thin films.

  5. An improved method of preparation of nanoparticular metal oxide catalysts

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention concerns an improved method of preparation of nanoparticular vanadium oxide/anatase titania catalysts having a narrow particle size distribution. In particular, the invention concerns preparation of nanoparticular vanadium oxide/anatase titania catalyst precursors comprising...... combustible crystallization seeds upon which the catalyst metal oxide is coprecipitated with the carrier metal oxide, which crystallization seeds are removed by combustion in a final calcining step.......The present invention concerns an improved method of preparation of nanoparticular vanadium oxide/anatase titania catalysts having a narrow particle size distribution. In particular, the invention concerns preparation of nanoparticular vanadium oxide/anatase titania catalyst precursors comprising...

  6. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    Energy Technology Data Exchange (ETDEWEB)

    KRUGER AA; HRMA PR

    2009-10-08

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  7. Growth and characterization of strontium tartrate pentahydrate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Firdous, A.; Ahmad, M.M. [Department of Physics, National Institute of Technology, Kashmir (India); Quasim, I.; Kotru, P.N. [Crystal Growth and Materials Research Laboratory, Department of Physics and Electronics, University of Jammu (India)

    2008-10-15

    Silica gel impregnated with L-tartaric acid and using strontium nitrate as the second reactant leads to the growth of well faceted strontium tartrate pentahydrate single crystals.The morphological developmen and internal cell dimensions are observed to be different from the ones reported in the literature for strontium tartrate trihydrate crystals. The crystals are characterized using XRD, CH analysis, SEM, FTIR spectroscopy and thermoanalytical techniques. The crystals are observed to be thermally stable upto about 105 C but thereafter start decomposing and ejecting water of hydration at various stages, finally reducing to strontium oxide. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Method for the preparation of photochromic insulating crystals

    Science.gov (United States)

    Abraham, Marvin M.; Boldu, Jose L.; Chen, Yok; Orera, Victor M.

    1986-01-01

    A method for preparing reversible-photochromic magnesium oxide (MgO) crystals. Single crystals of MgO doped with both lithium (Li) and nickel (Ni) are grown by a conventional arc fusion method. The as-grown crystals are characterized by an amber coloration. The crystals lose the amber coloration and become photochromic when they are thermochemically reduced by heating at temperatures greater than 1000.degree. K. in a hydrogen atmosphere. Alternate irradiation with UV and visible light result in rejuvenation and bleaching of the amber coloration, respectively.

  9. Crystallization of a stringent response factor from Aquifex aeolicus

    DEFF Research Database (Denmark)

    Kristensen, Ole; Laurberg, Martin; Gajhede, Michael

    2002-01-01

    The crystallization of a key enzyme from Aquifex aeolicus with suggested bifunctional activity, acting as an exopolyphosphatase and a guanosine pentaphosphate phosphohydrolase, is reported. Native data were collected to below 2 A resolution from an orthorhombic crystal with unit-cell parameters...... a = 50.8, b = 70.3, c = 90.9 A. Methionine residues were introduced by mutation and deliberate oxidation of the protein allowed us to produce additional crystal forms with reproducible diffraction ability and increased phasing potential. This is the first report on the crystallization of a member...

  10. Ergothioneine prevents copper-induced oxidative damage to DNA and protein by forming a redox-inactive ergothioneine-copper complex.

    Science.gov (United States)

    Zhu, Ben-Zhan; Mao, Li; Fan, Rui-Mei; Zhu, Jun-Ge; Zhang, Ying-Nan; Wang, Jing; Kalyanaraman, Balaraman; Frei, Balz

    2011-01-14

    Ergothioneine (2-mercaptohistidine trimethylbetaine) is a naturally occurring amino acid analogue found in up to millimolar concentrations in several tissues and biological fluids. However, the biological functions of ergothioneine remain incompletely understood. In this study, we investigated the role of ergothioneine in copper-induced oxidative damage to DNA and protein, using two copper-containing systems: Cu(II) with ascorbate and Cu(II) with H(2)O(2) [0.1 mM Cu(II), 1 mM ascorbate, and 1 mM H(2)O(2)]. Oxidative damage to DNA and bovine serum albumin was measured as strand breakage and protein carbonyl formation, respectively. Ergothioneine (0.1-1.0 mM) provided strong, dose-dependent protection against oxidation of DNA and protein in both copper-containing systems. In contrast, only limited protection was observed with the purported hydroxyl radical scavengers, dimethyl sulfoxide and mannitol, even at concentrations as high as 100 mM. Ergothioneine also significantly inhibited copper-catalyzed oxidation of ascorbate and competed effectively with histidine and 1,10-phenanthroline for binding of cuprous copper, but not cupric copper, as demonstrated by UV-visible and low-temperature electron spin resonance techniques. We conclude that ergothioneine is a potent, natural sulfur-containing antioxidant that prevents copper-dependent oxidative damage to biological macromolecules by forming a redox-inactive ergothioneine-copper complex.

  11. Effect of copper oxide electrocatalyst on CO2 reduction using Co3O4 as anode

    Directory of Open Access Journals (Sweden)

    V.S.K. Yadav

    2016-09-01

    Full Text Available The reduction of carbon dioxide (CO2 to products electrochemically (RCPE in 0.5 M NaHCO3 and Na2CO3 liquid phase electrolyte solutions was investigated. Cobalt oxide (Co3O4 as anode and cuprous oxide (Cu2O as the cathode were considered, respectively. The impacts of applied potential with time of reaction during reduction of CO2 to products were studied. The anode and cathode were prepared by depositing electrocatalysts on the graphite plate. Ultra-fast liquid chromatography (UFLC was used to analyze the products obtained from the reduction of CO2. The feasible way of reduction by applying voltages with current densities was clearly correlated. The results illustrate the capability of electrocatalyst successfully to remove atmospheric CO2 in the form of valuable chemicals. Maximum Faradaic efficiency of ethanol was 98.1% at 2 V and for formic acid (36.6% at 1.5 V was observed in NaHCO3. On the other hand, in Na2CO3 electrolyte solution maximum efficiency for ethanol was 55.21% at 1.5 V and 25.1% for formic acid at 2 V. In both electrolytes other end products like methanol, propanol, formaldehyde and acetic acid were formed at various applied voltage and output current densities.

  12. Copper(II) ion catalytic oxidation of o-phenylenediamine and characterization, X-ray crystal structure and solution studies of the final product [DAPH][H3O][Cu(dipic)2]·3H2O

    Science.gov (United States)

    Ghasemi, Khaled; Rezvani, Ali Reza; Shokrollahi, Ardeshir; Abdul Razak, Ibrahim; Refahi, Masoud; Moghimi, Abolghasem; Rosli, Mohd Mustaqim

    2015-09-01

    The complex [DAPH][H3O][Cu(dipic)2]·3H2O, (1) (dipicH2 = 2,6-pyridinedicarboxylic acid and DAP = 2,3-diaminophenazine) was prepared from the reaction of Cu(NO3)2·2H2O with mixture of o-phenylenediamine (OPD) and 2,6-pyridinedicarboxylic acid in water. The complex was characterized by FTIR, elemental analysis, UV-Vis and the single-crystal X-ray diffraction. The crystal system is monoclinic with the space group P21/c. This complex is stabilized in the solid state by an extensive network of hydrogen bonds between crystallized water, anionic and cationic fragments, which form a three-dimensional network. Furthermore, hydrogen bonds, π⋯π and Csbnd O⋯π stacking interactions seem to be effective in stabilizing the crystal structures. The protonation constants of dipic (L) and DAP (Q), the equilibrium constants for the dipic-DAP proton transfer system and the stoichiometry and stability constants of binary complexes including each of ligands (dipic, DAP) in presence Cu2+ ion, ternary complexes including, both of ligands (dipic-DAP) in presence of metal ion were calculated in aqueous solutions by potentiometric pH titration method using the Hyperquad2008 program. The stoichiometry of the most complexes species in solution was found to be very similar to the solid-state of cited metal ion complex.

  13. Electrochemical Quartz Crystal Nanobalance

    Science.gov (United States)

    Inzelt, György

    The method of piezoelectric microgravimetry (nanogravimetry) using an electrochemical quartz crystal microbalance (EQCM) or nanobalance (EQCN) can be considered as a novel and much more sensitive version of electrogravimetry. The EQCN technique has become a widely used technique in several areas of electrochemistry, electroanalytical chemistry, bioelectrochemistry, etc. [1-10]. Obviously, mass changes occurring during adsorption, sorption, electrosorption, electrodeposition, or spontaneous deposition can be followed, which is very helpful for the elucidation of reaction mechanism via identification of the species accumulated on the surface. These investigations include metal and alloy deposition, underpotential deposition, electroplating, synthesis of conducting polymers by electropolymerization, adsorption of biologically active materials, and analytical determination of small ions and biomolecules. Of course, the opposite processes, i.e., spontaneous dissolution, electrodissolution, corrosion, can also be studied. Electrochemical oscillations, in which the formation and oxidation of chemisorbed molecular fragments play a determining role, have been studied, too. The majority of the investigations have been devoted to ion and solvent transport associated with the redox transformations of electrochemically active polymers. Similar studies have been carried out regarding polynuclear surface layers such as metal hexacyanometalates as well as inorganic and organic microcrystals of different compositions.

  14. First Single-Crystal Mullite Fibers

    Science.gov (United States)

    1997-01-01

    Ceramic-matrix composites strengthened by suitable fiber additions are being developed for high-temperature use, particularly for aerospace applications. New oxide-based fibers, such as mullite, are particularly desirable because of their resistance to high-temperature oxidative environments. Mullite is a candidate material in both fiber and matrix form. The primary objective of this work was to determine the growth characteristics of single-crystal mullite fibers produced by the laser-heated floating zone method. Directionally solidified fibers with nominal mullite compositions of 3Al2O3 2SiO2 were grown by the laser-heated floating zone method at the NASA Lewis Research Center. SEM analysis revealed that the single-crystal fibers grown in this study were strongly faceted and that the facets act as critical flaws, limiting fiber strength. The average fiber tensile strength is 1.15 GPa at room temperature. The mullite fibers exhibit superior strength retention (80 percent of their room temperature tensile strength at 1450 C). Examined by transmission electron microscopy, these mullite single crystals are free of dislocations, low-angle boundaries, and voids. In addition, they show a high degree of oxygen vacancy ordering. High-resolution digital images from an optical microscope furnish evidence of the formation of a liquid-liquid miscibility gap during crystal growth. These images represent the first experimental evidence of liquid immiscibility for these compositions and temperatures. Continuing investigation with controlled seeding of mullite single crystals is planned.

  15. Crystal structure and prediction.

    Science.gov (United States)

    Thakur, Tejender S; Dubey, Ritesh; Desiraju, Gautam R

    2015-04-01

    The notion of structure is central to the subject of chemistry. This review traces the development of the idea of crystal structure since the time when a crystal structure could be determined from a three-dimensional diffraction pattern and assesses the feasibility of computationally predicting an unknown crystal structure of a given molecule. Crystal structure prediction is of considerable fundamental and applied importance, and its successful execution is by no means a solved problem. The ease of crystal structure determination today has resulted in the availability of large numbers of crystal structures of higher-energy polymorphs and pseudopolymorphs. These structural libraries lead to the concept of a crystal structure landscape. A crystal structure of a compound may accordingly be taken as a data point in such a landscape.

  16. Growth of dopamine crystals

    Energy Technology Data Exchange (ETDEWEB)

    Patil, Vidya, E-mail: vidya.patil@ruparel.edu; Patki, Mugdha, E-mail: mugdha.patki@ruparel.edu [D. G. Ruparel College, Senapati Bapat Marg, Mahim, Mumbai – 400 016 (India)

    2016-05-06

    Many nonlinear optical (NLO) crystals have been identified as potential candidates in optical and electro-optical devices. Use of NLO organic crystals is expected in photonic applications. Hence organic nonlinear optical materials have been intensely investigated due to their potentially high nonlinearities, and rapid response in electro-optic effect compared to inorganic NLO materials. There are many methods to grow organic crystals such as vapor growth method, melt growth method and solution growth method. Out of these methods, solution growth method is useful in providing constraint free crystal. Single crystals of Dopamine have been grown by evaporating the solvents from aqueous solution. Crystals obtained were of the size of orders of mm. The crystal structure of dopamine was determined using XRD technique. Images of crystals were obtained using FEG SEM Quanta Series under high vacuum and low KV.

  17. Growth of dopamine crystals

    Science.gov (United States)

    Patil, Vidya; Patki, Mugdha

    2016-05-01

    Many nonlinear optical (NLO) crystals have been identified as potential candidates in optical and electro-optical devices. Use of NLO organic crystals is expected in photonic applications. Hence organic nonlinear optical materials have been intensely investigated due to their potentially high nonlinearities, and rapid response in electro-optic effect compared to inorganic NLO materials. There are many methods to grow organic crystals such as vapor growth method, melt growth method and solution growth method. Out of these methods, solution growth method is useful in providing constraint free crystal. Single crystals of Dopamine have been grown by evaporating the solvents from aqueous solution. Crystals obtained were of the size of orders of mm. The crystal structure of dopamine was determined using XRD technique. Images of crystals were obtained using FEG SEM Quanta Series under high vacuum and low KV.

  18. ALICE photon spectrometer crystals

    CERN Multimedia

    Maximilien Brice

    2006-01-01

    Members of the mechanical assembly team insert the last few crystals into the first module of ALICE's photon spectrometer. These crystals are made from lead-tungstate, a crystal as clear as glass but with nearly four times the density. When a high-energy particle passes through one of these crystals it will scintillate, emitting a flash of light allowing the energy of photons, electrons and positrons to be measured.

  19. Crystallization from Gels

    Science.gov (United States)

    Narayana Kalkura, S.; Natarajan, Subramanian

    Among the various crystallization techniques, crystallization in gels has found wide applications in the fields of biomineralization and macromolecular crystallization in addition to crystallizing materials having nonlinear optical, ferroelectric, ferromagnetic, and other properties. Furthermore, by using this method it is possible to grow single crystals with very high perfection that are difficult to grow by other techniques. The gel method of crystallization provides an ideal technique to study crystal deposition diseases, which could lead to better understanding of their etiology. This chapter focuses on crystallization in gels of compounds that are responsible for crystal deposition diseases. The introduction is followed by a description of the various gels used, the mechanism of gelling, and the fascinating phenomenon of Liesegang ring formation, along with various gel growth techniques. The importance and scope of study on crystal deposition diseases and the need for crystal growth experiments using gel media are stressed. The various crystal deposition diseases, viz. (1) urolithiasis, (2) gout or arthritis, (3) cholelithiasis and atherosclerosis, and (4) pancreatitis and details regarding the constituents of the crystal deposits responsible for the pathological mineralization are discussed. Brief accounts of the theories of the formation of urinary stones and gallstones and the role of trace elements in urinary stone formation are also given. The crystallization in gels of (1) the urinary stone constituents, viz. calcium oxalate, calcium phosphates, uric acid, cystine, etc., (2) the constituents of the gallstones, viz. cholesterol, calcium carbonate, etc., (3) the major constituent of the pancreatic calculi, viz., calcium carbonate, and (4) cholic acid, a steroidal hormone are presented. The effect of various organic and inorganic ions, trace elements, and extracts from cereals, herbs, and fruits on the crystallization of major urinary stone and gallstone

  20. CRYSTAL FILTER TEST SET

    Science.gov (United States)

    CRYSTAL FILTERS, *HIGH FREQUENCY, *RADIOFREQUENCY FILTERS, AMPLIFIERS, ELECTRIC POTENTIAL, FREQUENCY, IMPEDANCE MATCHING , INSTRUMENTATION, RADIOFREQUENCY, RADIOFREQUENCY AMPLIFIERS, TEST EQUIPMENT, TEST METHODS