Science.gov

Sample records for copper selenides

  1. Formation of copper-indium-selenide and/or copper-indium-gallium-selenide films from indium selenide and copper selenide precursors

    DOEpatents

    Curtis, Calvin J [Lakewood, CO; Miedaner, Alexander [Boulder, CO; Van Hest, Maikel [Lakewood, CO; Ginley, David S [Evergreen, CO; Nekuda, Jennifer A [Lakewood, CO

    2011-11-15

    Liquid-based indium selenide and copper selenide precursors, including copper-organoselenides, particulate copper selenide suspensions, copper selenide ethylene diamine in liquid solvent, nanoparticulate indium selenide suspensions, and indium selenide ethylene diamine coordination compounds in solvent, are used to form crystalline copper-indium-selenide, and/or copper indium gallium selenide films (66) on substrates (52).

  2. Precursors for formation of copper selenide, indium selenide, copper indium diselenide, and/or copper indium gallium diselenide films

    DOEpatents

    Curtis, Calvin J; Miedaner, Alexander; Van Hest, Maikel; Ginley, David S

    2014-11-04

    Liquid-based precursors for formation of Copper Selenide, Indium Selenide, Copper Indium Diselenide, and/or copper Indium Galium Diselenide include copper-organoselenides, particulate copper selenide suspensions, copper selenide ethylene diamine in liquid solvent, nanoparticulate indium selenide suspensions, and indium selenide ethylene diamine coordination compounds in solvent. These liquid-based precursors can be deposited in liquid form onto substrates and treated by rapid thermal processing to form crystalline copper selenide and indium selenide films.

  3. Oxidation Mechanism of Copper Selenide

    NASA Astrophysics Data System (ADS)

    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.

  4. Thermoelectric Study of Copper Selenide

    NASA Astrophysics Data System (ADS)

    Yao, Mengliang; Liu, Weishu; Ren, Zhifeng; Opeil, Cyril

    2014-03-01

    Nanostructuring has been shown to be an effective approach in reducing lattice thermal conductivity and improving the figure of merit of thermoelectric materials. Copper selenide is a layered structure material, which has a low thermal conductivity and p-type Seebeck coefficient at low temperatures. We have evaluated several hot-pressed, nanostructured copper selenide samples with different dopants for their thermoelectric properties. The phenomenon of the charge-density wave observed in the nanocomposite, resistivity, Seebeck, thermal conductivity and carrier mobility will be discussed. Funding for this research was provided by the Solid State Solar - Thermal Energy Conversion Center (S3TEC), an Energy Frontier Research Center sponsored by the DOE, Office of Basic Energy Science, Award No. DE-SC0001299/ DE-FG02-09ER46577.

  5. 40 CFR 721.10391 - Copper gallium indium selenide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Copper gallium indium selenide. 721... Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as copper gallium indium selenide (PMN...

  6. 40 CFR 721.10391 - Copper gallium indium selenide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Copper gallium indium selenide. 721... Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as copper gallium indium selenide (PMN...

  7. 40 CFR 721.10391 - Copper gallium indium selenide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Copper gallium indium selenide. 721... Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as copper gallium indium selenide (PMN...

  8. Photoluminescence Study of Copper Selenide Thin Films

    NASA Astrophysics Data System (ADS)

    Urmila, K. S.; Asokan, T. Namitha; Pradeep, B.

    2011-10-01

    Thin films of Copper Selenide of composition of composition Cu7Se4 with thickness 350 nm are deposited on glass substrate at a temperature of 498 K±5 K and pressure of 10-5 mbar using reactive evaporation, a variant of Gunther's three temperature method with high purity Copper (99.999%) and Selenium (99.99%) as the elemental starting material. The deposited film is characterized structurally using X-ray Diffraction. The structural parameters such as lattice constant, particle size, dislocation density; number of crystallites per unit area and strain in the film are evaluated. Photoluminescence of the film is analyzed at room temperature using Fluoro Max-3 Spectrofluorometer.

  9. Copper Selenide Nanocrystals for Photothermal Therapy

    PubMed Central

    Hessel, Colin M.; Pattani, Varun; Rasch, Michael; Panthani, Matthew G.; Koo, Bonil; Tunnell, James W.; Korgel, Brian A.

    2011-01-01

    Ligand-stabilized copper selenide (Cu2−xSe) nanocrystals, approximately 16 nm in diameter, were synthesized by a colloidal hot injection method and coated with amphiphilic polymer. The nanocrystals readily disperse in water and exhibit strong near infrared (NIR) optical absorption with a high molar extinction coefficient of 7.7 × 107 cm−1 M−1 at 980 nm. When excited with 800 nm light, the Cu2−xSe nanocrystals produce significant photothermal heating with a photothermal transduction efficiency of 22%, comparable to nanorods and nanoshells of gold (Au). In vitro photothermal heating of Cu2−xSe nanocrystals in the presence of human colorectal cancer cell (HCT-116) led to cell destruction after 5 minutes of laser irradiation at 33 W/cm2, demonstrating the viabilitiy of Cu2−xSe nanocrystals for photothermal therapy applications. PMID:21553924

  10. Copper selenide nanocrystals for photothermal therapy.

    PubMed

    Hessel, Colin M; Pattani, Varun P; Rasch, Michael; Panthani, Matthew G; Koo, Bonil; Tunnell, James W; Korgel, Brian A

    2011-06-08

    Ligand-stabilized copper selenide (Cu(2-x)Se) nanocrystals, approximately 16 nm in diameter, were synthesized by a colloidal hot injection method and coated with amphiphilic polymer. The nanocrystals readily disperse in water and exhibit strong near-infrared (NIR) optical absorption with a high molar extinction coefficient of 7.7 × 10(7) cm(-1) M(-1) at 980 nm. When excited with 800 nm light, the Cu(2-x)Se nanocrystals produce significant photothermal heating with a photothermal transduction efficiency of 22%, comparable to nanorods and nanoshells of gold (Au). In vitro photothermal heating of Cu(2-x)Se nanocrystals in the presence of human colorectal cancer cell (HCT-116) led to cell destruction after 5 min of laser irradiation at 33 W/cm(2), demonstrating the viabilitiy of Cu(2-x)Se nanocrystals for photothermal therapy applications.

  11. Deposition of copper selenide thin films and nanoparticles

    NASA Astrophysics Data System (ADS)

    Hu, Yunxiang; Afzaal, Mohammad; Malik, Mohammad A.; O'Brien, Paul

    2006-12-01

    A new method is reported for the growth of copper selenide thin films and nanoparticles using copper acetylacetonate and trioctylphosphine selenide. Aerosol-assisted chemical vapor deposition experiments lead to successful deposition of tetragonal Cu 2Se films. In contrast, hexadecylamine capped nanoparticles are composed of cubic Cu 2-xSe. The deposited materials are optically and structurally characterized. The results of this comprehensive study are described and discussed.

  12. Mechanism of copper selenide growth on copper-oxide selenium system

    NASA Astrophysics Data System (ADS)

    Ishikawa, Y.; Kido, O.; Kimura, Y.; Kurumada, M.; Suzuki, H.; Saito, Y.; Kaito, C.

    2004-01-01

    Transmission electron microscopy was used to study spontaneous copper selenide formation on Cu particles covered with an oxide layer. Even if the copper particle surface was covered with a Cu 2O layer, selenides were formed by diffusion through the metal oxide layer. For a particle size less than 50 nm, selenide was formed in Cu particles by the diffusion of Se atoms passing through the Cu 2O layer. For particles larger than 100 nm in size, selenide was formed in Se film. It was also found that the thickness of the Cu 2O layer on the surface of Cu particle accelerated diffusion of Se atoms to the copper particle.

  13. Electrodeposition of copper selenide films from acidic bath and their properties

    NASA Astrophysics Data System (ADS)

    Mane, Rajaram S.; Shaikh, Arif V.; Joo, Oh-Shim; Han, Sung-Hwan; Pathan, Habib M.

    2012-06-01

    Copper selenide thin films are successfully deposited using electrodeposition method by combining copper sulfate and sodiumseleno sulfate precursors at room temperature in acidic bath. The chemical composition was a key factor in preparing high-quality uniform and smooth thin films of the copper selenide. We present indium-tin-oxide as a substrate for depositing copper selenide films which usually exists as copper (I) selenide or copper (II) selenide. Obtained brownish films of copper selenide are examined for their structural, morphological, compositional and optical properties by means of X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and optical absorption measurement techniques, respectively for the structural, morphological and optical analysis.

  14. Aqueous preparation of surfactant-free copper selenide nanowires.

    PubMed

    Chen, Xinqi; Li, Zhen; Yang, Jianping; Sun, Qiao; Dou, Shixue

    2015-03-15

    Uniform surfactant-free copper selenide (Cu2-xSe) nanowires were prepared via an aqueous route. The effects of reaction parameters such as Cu/Se precursor ratio, Se/NaOH ratio, and reaction time on the formation of nanowires were comprehensively investigated. The results show that Cu2-xSe nanowires were formed through the assembling of CuSe nanoplates, accompanied by their self-redox reactions. The resultant Cu2-xSe nanowires were explored as a potential thermoelectric candidate in comparison with commercial copper selenide powder. Both synthetic and commercial samples have a similar performance and their figures of merit are 0.29 and 0.38 at 750K, respectively.

  15. Ambient Facile Synthesis of Gram-Scale Copper Selenide Nanostructures from Commercial Copper and Selenium Powder.

    PubMed

    Chen, Xin Qi; Li, Zhen; Dou, Shi Xue

    2015-06-24

    Grams of copper selenides (Cu(2-x)Se) were prepared from commercial copper and selenium powders in the presence of thiol ligands by a one-pot reaction at room temperature. The resultant copper selenides are a mixture of nanoparticles and their assembled nanosheets, and the thickness of nanosheets assembled is strongly dependent on the ratio of thiol ligand to selenium powder. The resultant Cu(2-x)Se nanostructures were treated with hydrazine solution to remove the surface ligands and then explored as a potential thermoelectric candidate in comparison with commercial copper selenide powders. The research provides a novel ambient approach for preparation of Cu(2-x)Se nanocrystallines on a large scale for various applications.

  16. Sonochemical synthesis of copper selenides nanocrystals with different phases

    NASA Astrophysics Data System (ADS)

    Xu, Shu; Wang, Hui; Zhu, Jun-Jie; Chen, Hong-Yuan

    2002-01-01

    A series of copper selenides (Cu 2- xSe, Cu 3Se 2 and CuSe) nanocrystals were prepared by a sonochemical method based on the reaction of copper acetate and sodium selenosulfate in an aqueous system. The phases and sizes of the nanocrystals could be controlled by changing the ratio of [Cu 2+]/[SeSO 32-] and complexing agents. X-ray powder diffraction and transmission electron microscopy were used to determine the phase, purity, size and morphology of the products.

  17. Copper selenide thin films by chemical bath deposition

    NASA Astrophysics Data System (ADS)

    García, V. M.; Nair, P. K.; Nair, M. T. S.

    1999-05-01

    We report the structural, optical, and electrical properties of thin films (0.05 to 0.25 μm) of copper selenide obtained from chemical baths using sodium selenosulfate or N,N-dimethylselenourea as a source of selenide ions. X-ray diffraction (XRD) studies on the films obtained from baths using sodium selenosulfate suggest a cubic structure as in berzelianite, Cu 2- xSe with x=0.15. Annealing the films at 400°C in nitrogen leads to a partial conversion of the film to Cu 2Se. In the case of films obtained from the baths containing dimethylselenourea, the XRD patterns match that of klockmannite, CuSe. Annealing these films in nitrogen at 400°C results in loss of selenium, and consequently a composition rich in copper, similar to Cu 2- xSe, is reached. Optical absorption in the films result from free carrier absorption in the near infrared region with absorption coefficient of ˜10 5 cm -1. Band-to-band transitions which gives rise to the optical absorption in the visible-ultraviolet region may be interpreted in terms of direct allowed transitions with band gap in the 2.1-2.3 eV range and indirect allowed transitions with band gap 1.2-1.4 eV. All the films, as prepared and annealed, show p-type conductivity, in the range of (1-5)×10 3 Ω -1 cm -1. This results in high near infrared reflectance, of 30-80%.

  18. Cu Vacancies Boost Cation Exchange Reactions in Copper Selenide Nanocrystals

    PubMed Central

    2015-01-01

    We have investigated cation exchange reactions in copper selenide nanocrystals using two different divalent ions as guest cations (Zn2+ and Cd2+) and comparing the reactivity of close to stoichiometric (that is, Cu2Se) nanocrystals with that of nonstoichiometric (Cu2–xSe) nanocrystals, to gain insights into the mechanism of cation exchange at the nanoscale. We have found that the presence of a large density of copper vacancies significantly accelerated the exchange process at room temperature and corroborated vacancy diffusion as one of the main drivers in these reactions. Partially exchanged samples exhibited Janus-like heterostructures made of immiscible domains sharing epitaxial interfaces. No alloy or core–shell structures were observed. The role of phosphines, like tri-n-octylphosphine, in these reactions, is multifaceted: besides acting as selective solvating ligands for Cu+ ions exiting the nanoparticles during exchange, they also enable anion diffusion, by extracting an appreciable amount of selenium to the solution phase, which may further promote the exchange process. In reactions run at a higher temperature (150 °C), copper vacancies were quickly eliminated from the nanocrystals and major differences in Cu stoichiometries, as well as in reactivities, between the initial Cu2Se and Cu2–xSe samples were rapidly smoothed out. These experiments indicate that cation exchange, under the specific conditions of this work, is more efficient at room temperature than at higher temperature. PMID:26140622

  19. Cu Vacancies Boost Cation Exchange Reactions in Copper Selenide Nanocrystals.

    PubMed

    Lesnyak, Vladimir; Brescia, Rosaria; Messina, Gabriele C; Manna, Liberato

    2015-07-29

    We have investigated cation exchange reactions in copper selenide nanocrystals using two different divalent ions as guest cations (Zn(2+) and Cd(2+)) and comparing the reactivity of close to stoichiometric (that is, Cu2Se) nanocrystals with that of nonstoichiometric (Cu(2-x)Se) nanocrystals, to gain insights into the mechanism of cation exchange at the nanoscale. We have found that the presence of a large density of copper vacancies significantly accelerated the exchange process at room temperature and corroborated vacancy diffusion as one of the main drivers in these reactions. Partially exchanged samples exhibited Janus-like heterostructures made of immiscible domains sharing epitaxial interfaces. No alloy or core-shell structures were observed. The role of phosphines, like tri-n-octylphosphine, in these reactions, is multifaceted: besides acting as selective solvating ligands for Cu(+) ions exiting the nanoparticles during exchange, they also enable anion diffusion, by extracting an appreciable amount of selenium to the solution phase, which may further promote the exchange process. In reactions run at a higher temperature (150 °C), copper vacancies were quickly eliminated from the nanocrystals and major differences in Cu stoichiometries, as well as in reactivities, between the initial Cu2Se and Cu(2-x)Se samples were rapidly smoothed out. These experiments indicate that cation exchange, under the specific conditions of this work, is more efficient at room temperature than at higher temperature.

  20. Characterization of single phase copper selenide nanoparticles and their growth mechanism

    NASA Astrophysics Data System (ADS)

    Patidar, D.; Saxena, N. S.

    2012-03-01

    The high quality Cu3Se2 phase of copper selenide nanoparticles was synthesized through the solution-phase chemical reaction between copper and selenium. In this synthesis process, hydrazine hydrate acts as reducing agent whereas ethylene glycol controls the nucleation and growth of particles. An effort has been made to explain the growth mechanism to form copper selenide nanoparticles through the coordination of selenium to the Cu2+ complexes with OH groups of ethylene glycol. Result indicates the formation of Cu3Se2 single phase nanoparticles. The particles with the average particle size 25 nm are spherical in shape having tetragonal structure. The particles are well crystallized having 94% degree of crystallinity. An effort has also been made to determine the energy band gap of copper selenide nanoparticles through the absorption spectra.

  1. Using different chemical methods for deposition of copper selenide thin films and comparison of their characterization.

    PubMed

    Güzeldir, Betül; Sağlam, Mustafa

    2015-11-05

    Different chemical methods such as Successive Ionic Layer Adsorption and Reaction (SILAR), spin coating and spray pyrolysis methods were used to deposite of copper selenide thin films on the glass substrates. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray analysis (EDX) spectroscopy and UV-vis spectrophotometry. The XRD and SEM studies showed that all the films exhibit polycrystalline nature and crystallinity of copper selenide thin films prepared with spray pyrolysis greater than spin coating and SILAR methods. From SEM and AFM images, it was observed copper selenide films were uniform on the glass substrates without any visible cracks or pores. The EDX spectra showed that the expected elements exist in the thin films. Optical absorption studies showed that the band gaps of copper selenide thin films were in the range 2.84-2.93 eV depending on different chemical methods. The refractive index (n), optical static and high frequency dielectric constants (ε0, ε∞) values were calculated by using the energy bandgap values for each deposition method. The obtained results from different chemical methods revealed that the spray pyrolysis technique is the best chemical deposition method to fabricate copper selenide thin films. This absolute advantage was lead to play key roles on performance and efficiency electrochromic and photovoltaic devices.

  2. Photoconductivity in reactively evaporated copper indium selenide thin films

    SciTech Connect

    Urmila, K. S. Asokan, T. Namitha Pradeep, B.; Jacob, Rajani; Philip, Rachel Reena

    2014-01-28

    Copper indium selenide thin films of composition CuInSe{sub 2} with thickness of the order of 130 nm are deposited on glass substrate at a temperature of 423 ±5 K and pressure of 10{sup −5} mbar using reactive evaporation, a variant of Gunther's three temperature method with high purity Copper (99.999%), Indium (99.999%) and Selenium (99.99%) as the elemental starting materials. X-ray diffraction (XRD) studies shows that the films are polycrystalline in nature having preferred orientation of grains along the (112) plane. The structural type of the film is found to be tetragonal with particle size of the order of 32 nm. The structural parameters such as lattice constant, particle size, dislocation density, number of crystallites per unit area and strain in the film are also evaluated. The surface morphology of CuInSe{sub 2} films are studied using 2D and 3D atomic force microscopy to estimate the grain size and surface roughness respectively. Analysis of the absorption spectrum of the film recorded using UV-Vis-NIR Spectrophotometer in the wavelength range from 2500 nm to cutoff revealed that the film possess a direct allowed transition with a band gap of 1.05 eV and a high value of absorption coefficient (α) of 10{sup 6} cm{sup −1} at 570 nm. Photoconductivity at room temperature is measured after illuminating the film with an FSH lamp (82 V, 300 W). Optical absorption studies in conjunction with the good photoconductivity of the prepared p-type CuInSe{sub 2} thin films indicate its suitability in photovoltaic applications.

  3. High-temperature conductivity in chemical bath deposited copper selenide thin films

    NASA Astrophysics Data System (ADS)

    Dhanam, M.; Manoj, P. K.; Prabhu, Rajeev. R.

    2005-07-01

    This paper reports high-temperature (305-523 K) electrical studies of chemical bath deposited copper (I) selenide (Cu 2-xSe) and copper (II) selenide (Cu 3Se 2) thin films. Cu 2-xSe and Cu 3Se 2 have been prepared on glass substrates from the same chemical bath at room temperature by controlling the pH. From X-ray diffraction (XRD) profiles, it has been found that Cu 2-xSe and Cu 3Se 2 have cubic and tetragonal structures, respectively. The composition of the chemical constituent in the films has been confirmed from XRD data and energy-dispersive X-ray analysis (EDAX). It has been found that both phases of copper selenide thin films have thermally activated conduction in the high-temperature range. In this paper we also report the variation of electrical parameters with film thickness and the applied voltage.

  4. The effect of annealing on vacuum-evaporated copper selenide and indium telluride thin films

    SciTech Connect

    Peranantham, P.; Jeyachandran, Y.L.; Viswanathan, C.; Praveena, N.N.; Chitra, P.C.; Mangalaraj, D. . E-mail: dmraj800@yahoo.com; Narayandass, Sa. K.

    2007-08-15

    Copper selenide and indium telluride thin films were prepared by a vacuum evaporation technique. The as-deposited films were annealed in a vacuum at different temperatures and the influence on composition, structure and optical properties of copper selenide and indium telluride films was investigated using energy dispersive X-ray analysis, X-ray diffraction, scanning electron microscopy and optical transmission measurements. From the compositional analysis, the as-deposited copper selenide and indium telluride films which were annealed at 473 and 523 K, respectively, were found to possess the nearly stoichiometric composition of CuSe and InTe phases. However, the films annealed at 673 K showed the composition of Cu{sub 2}Se and In{sub 4}Te{sub 3} phases. The structural parameters such as, particle size and strain were determined using X-ray diffractograms of the films. Optical transmittance measurements indicated the existence of direct and indirect transitions in copper selenide films and an indirect allowed transition in indium telluride films.

  5. Characterization of copper selenide thin films deposited by chemical bath deposition technique

    NASA Astrophysics Data System (ADS)

    Al-Mamun; Islam, A. B. M. O.

    2004-11-01

    A low-cost chemical bath deposition (CBD) technique has been used for the preparation of Cu2-xSe thin films onto glass substrates and deposited films were characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and UV-vis spectrophotometry. Good quality thin films of smooth surface of copper selenide thin films were deposited using sodium selenosulfate as a source of selenide ions. The structural and optical behaviour of the films are discussed in the light of the observed data.

  6. Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Ambade, Swapnil B.; Mane, R. S.; Kale, S. S.; Sonawane, S. H.; Shaikh, Arif V.; Han, Sung-Hwan

    2006-12-01

    Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 °C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu 2- xSe phase was confirmed by XRD pattern and spherical grains of 30 ± 4 - 40 ± 4 nm in size aggregated over about 130 ± 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm 2 light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells.

  7. Metal ions to control the morphology of semiconductor nanoparticles: copper selenide nanocubes.

    PubMed

    Li, Wenhua; Zamani, Reza; Ibáñez, Maria; Cadavid, Doris; Shavel, Alexey; Morante, Joan Ramon; Arbiol, Jordi; Cabot, Andreu

    2013-03-27

    Morphology is a key parameter in the design of novel nanocrystals and nanomaterials with controlled functional properties. Here, we demonstrate the potential of foreign metal ions to tune the morphology of colloidal semiconductor nanoparticles. We illustrate the underlying mechanism by preparing copper selenide nanocubes in the presence of Al ions. We further characterize the plasmonic properties of the obtained nanocrystals and demonstrate their potential as a platform to produce cubic nanoparticles with different composition by cation exchange.

  8. Copper selenide nanowires and nanocrystallites in alumina: Carrier relaxation, recombination, and trapping

    NASA Astrophysics Data System (ADS)

    Statkutė, G.; Tomašiùnas, R.; Jagminas, A.

    2007-06-01

    Nonequilibrium carrier dynamics in copper selenide (Cu2-δSe δ=0.15, Cu3Se2) nanowires (diameter ≈18 nm, height ≈2 μm) and nanocrystallites (diameter≈18 nm) in femto- and picosecond time domains by the means of a transient dynamic grating technique were investigated. Bulk and quantum confinement approaches were used to fit the experimental results using nonequilibrium carrier fast relaxation, recombination, and trapping mechanisms. A nonradiative Auger recombination was concluded to be the main mechanism of nonequilibrium carrier recombination. The Auger coefficient for copper selenide was estimated of the order of 10-30-10-29 cm6 s-1. Hole trapping at shallow impurity centers in nanowires was interpreted. From calculating the experimental results the trapping parameters and high concentration of centers >1020 cm-3 were evaluated. Finally, direct measurement of carrier lifetime in copper selenide nanostructures showed values of the order of ≈10-10 s. Samples were characterized by the means of transmission electron microscopy, scanning electron microscopy, x-ray diffraction, and optical spectroscopy.

  9. Surface-initiated atom transfer radical polymerization-induced transformation of selenium nanowires into copper selenide@polystyrene core-shell nanowires.

    PubMed

    Wang, Michael C P; Gates, Byron D

    2013-10-09

    This Article reports the first preparation of cuprous and cupric selenide nanowires coated with a ∼5 nm thick sheath of polystyrene (copper selenide@polystyrene). These hybrid nanostructures are prepared by the transformation of selenium nanowires in a one-pot reaction, which is performed under ambient conditions. The composition, purity, and crystallinity of the copper selenide@polystyrene products were assessed by scanning transmission electron microscopy, electron energy-loss spectroscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy techniques. We determined that the single crystalline selenium nanowires are converted into polycrystalline copper selenide@polystyrene nanowires containing both cuprous selenide and cupric selenide. The product is purified through the selective removal of residual, non-transformed selenium nanowires by performing thermal evaporation below the decomposition temperature of these copper selenides. Powder X-ray diffraction of the purified copper selenide nanowires@polystyrene identified the presence of hexagonal, cubic, and orthorhombic phases of copper selenide. These purified cuprous and cupric selenide@polystyrene nanowires have an indirect bandgap of 1.44 eV, as determined by UV-vis absorption spectroscopy. This new synthesis of polymer-encapsulated nanoscale materials may provide a method for preparing other complex hybrid nanostructures.

  10. Simultaneous phase and morphology controllable synthesis of copper selenide films by microwave-assisted nonaqueous approach

    NASA Astrophysics Data System (ADS)

    Li, Jing; Fa, Wenjun; Li, Yasi; Zhao, Hongxiao; Gao, Yuanhao; Zheng, Zhi

    2013-02-01

    Copper selenide films with different phase and morphology were synthesized on copper substrate through controlling reaction solvent by microwave-assisted nonaqueous approach. The films were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The result showed that the pure films could be obtained using cyclohexyl alcohol or benzyl alcohol as solvent. The cubic Cu2-xSe dendrites were synthesized in cyclohexyl alcohol reaction system and hexagonal CuSe flaky crystals were obtained with benzyl alcohol as solvent.

  11. Copper and silver selenide crystal growth rate measurements as a method for determination of ionic conductivity

    NASA Astrophysics Data System (ADS)

    Vučić, Zlatko; Lovrić, Davorin; Gladić, Jadranko; Etlinger, Božidar

    2004-03-01

    The motivation behind this work is the discrepancy between the measured and calculated growth rates of copper selenide spherical single crystals between 740 and 800 K. The growth of cylindrical polycrystalline samples of copper selenide at high temperatures was monitored in experiments that enabled full control of the geometry of growth. Together with the calculations based on Yokota's transport equation, these measurements eliminated ionic conductivity data as a possible reason behind too high values of the calculated growth rates. The equivalent growth experiments on polycrystalline silver selenide samples were performed as a test of the method, yielding excellent agreement with the results obtained by extrapolation of existing data. On the basis of these measurements and associated analysis, this method is proposed as a method for determination of ionic conductivity of mixed superionic conductors on temperatures up to the temperatures of melting, i.e. in the range in which other methods of ionic conductivity measurements either do not work or are not accurate enough.

  12. Sonochemical synthesis and mechanistic study of copper selenides Cu(2-x)Se, beta-CuSe, and Cu(3)Se(2).

    PubMed

    Xie, Yi; Zheng, Xiuwen; Jiang, Xuchuan; Lu, Jun; Zhu, Liying

    2002-01-28

    Nanocrystallites of nonstoichiometric copper selenide (Cu(2-x)Se) and stoichiometric copper selenides (beta-CuSe and Cu(3)Se(2)) were synthesized in different solutions via sonochemical irradiation at room temperature. The influence of solvents, surfactants, and ultrasonic irradiation on the morphology and phase of products has been investigated. The morphological difference of the products was mainly affected by the solvents and surfactants, which can self-aggregate into lamellar structures or microemulsions, and then these unique structures can act as both supramolecular template and microreactor to direct the growth of copper selenides. On the other hand, it was also found that the sonochemical irradiation and solvents played an important role in the formation of different phases of copper selenides. The proposed formation mechanism of copper selenides is discussed.

  13. Relaxation of Electronic and Ionic Polarization in Liquid Copper Selenide

    NASA Astrophysics Data System (ADS)

    Itoh, Keiji; Maruyama, Kenji; Misawa, Masakatsu; Tamaki, Shigeru

    2002-01-01

    The diffusion constants of both cation and anion in liquid Cu2Se have been measured based on the time dependence of decaying residual potential due to the charge polarization after the turning-off of applied current. The experimental decaying curves were fitted by three exponential terms. Two terms correspond to the diffusion process of copper and selenium ions, respectively, and the rest is attributed to a relaxation of electronic polarization. It is found that the temperature dependences of diffusion constants of copper and selenium ions are negligibly small, on the other hand, the relaxation time of electronic polarization increases with increasing temperature.

  14. Methods of making copper selenium precursor compositions with a targeted copper selenide content and precursor compositions and thin films resulting therefrom

    DOEpatents

    Curtis, Calvin J.; Miedaner, Alexander; van Hest, Marinus Franciscus Antonius Maria; Ginley, David S.; Leisch, Jennifer; Taylor, Matthew; Stanbery, Billy J.

    2011-09-20

    Precursor compositions containing copper and selenium suitable for deposition on a substrate to form thin films suitable for semi-conductor applications. Methods of forming the precursor compositions using primary amine solvents and methods of forming the thin films wherein the selection of temperature and duration of heating controls the formation of a targeted species of copper selenide.

  15. Band structure and transport studies of copper selenide: An efficient thermoelectric material

    NASA Astrophysics Data System (ADS)

    Tyagi, Kriti; Gahtori, Bhasker; Bathula, Sivaiah; Auluck, S.; Dhar, Ajay

    2014-10-01

    We report the band structure calculations for high temperature cubic phase of copper selenide (Cu2Se) employing Hartree-Fock approximation using density functional theory within the generalized gradient approximation. These calculations were further extended to theoretically estimate the electrical transport coefficients of Cu2Se employing Boltzmann transport theory, which show a reasonable agreement with the corresponding experimentally measured values. The calculated transport coefficients are discussed in terms of the thermoelectric (TE) performance of this material, which suggests that Cu2Se can be a potential p-type TE material with an optimum TE performance at a carrier concentration of ˜ 4 - 6 × 10 21 cm - 3 .

  16. Ion beam analysis of copper selenide thin films prepared by chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Andrade, E.; García, V. M.; Nair, P. K.; Nair, M. T. S.; Zavala, E. P.; Huerta, L.; Rocha, M. F.

    2000-03-01

    Analyses of Rutherford back scattered (RBS) 4He+-particle spectra of copper selenide thin films deposited on glass slides by chemical bath were carried out to determine the changes brought about in the thin film by annealing processes. The atomic density per unit area and composition of the films were obtained from these measurements. This analysis shows that annealing in a nitrogen atmosphere at 400°C leads to the conversion of Cu xSe thin film to Cu 2Se. Results of X-ray diffraction, optical, and electrical characteristics on the films are presented to supplement the RBS results.

  17. Structural, morphology and electrical properties of layered copper selenide thin film

    NASA Astrophysics Data System (ADS)

    Ying Chyi Liew, J.; Talib, Zainal; Mahmood, W.; Yunus, M.; Zainal, Zulkarnain; Halim, Shaari; Moksin, Mohd; Yusoff, Wan; Pah Lim, K.

    2009-06-01

    Thin films of copper selenide (CuSe) were physically deposited layer-by-layer up to 5 layers using thermal evaporation technique onto a glass substrate. Various film properties, including the thickness, structure, morphology, surface roughness, average grain size and electrical conductivity are studied and discussed. These properties are characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), ellipsometer and 4 point probe at room temperature. The dependence of electrical conductivity, surface roughness, and average grain size on number of layers deposited is discussed.

  18. USE OF ELECTRICALLY CONDUCTING COATINGS OF COPPER SELENIDE AND COATINGS COMPOSED OF Cu3PSx FOR PREPARING ELECTROLUMINESCENT CAPACITORS,

    DTIC Science & Technology

    polymer ribbons are discussed. Copper selenide coatings are produced by vacuum deposition of Cu2Se . Heating the object afterwards at 70-80C for 30-60...the coating. Transmission characteristics of this coating are similar to those of the Cu2Se coating. A detailed explanation is given of the methods

  19. Effects of residual copper selenide on CuInGaSe 2 solar cells

    NASA Astrophysics Data System (ADS)

    Hsieh, Tung-Po; Chuang, Chia-Chih; Wu, Chung-Shin; Chang, Jen-Chuan; Guo, Jhe-Wei; Chen, Wei-Chien

    2011-02-01

    Large-grain, copper-poor CuInGaSe2 (CIGS) films are favored in the fabrication of highly efficient solar cells. However, the degradation of cell performance caused by residual copper selenide (Cu2-xSe) remains a problem. This work studies the formation and behavior of excess CuxSe and further compares the cell performance of typical copper-poor with that of copper-rich solar cells. Since excess Cu2-xSe cannot be exhausted during the growth, it fully surrounds the polycrystalline CIGS grains. Excess Cu2-xSe in the CIGS film produces serious shunt paths and causes the pn junction to be of poor quality. A short circuit in copper-rich CIGS solar cells is attributable to the conductive Cu2-xSe. The best way to ensure high-efficiency of the cells is to exhaust Cu2-xSe during growth. Otherwise, a dense, chemically treated CIGS film is required to prevent the negative effects of excess Cu2-xSe.

  20. Specific features of photoluminescence properties of copper-doped cadmium selenide quantum dots

    SciTech Connect

    Tselikov, G. I.; Dorofeev, S. G.; Tananaev, P. N.; Timoshenko, V. Yu.

    2011-09-15

    The effect of doping with copper on the photoluminescence properties of cadmium selenide quantum dots 4 nm in dimension is studied. The quenching of the excitonic photoluminescence band related to the quantum dots and the appearance of an impurity photoluminescence band in the near-infrared region are observed after doping of the quantum dots with copper. It is established that, on doping of the quantum dots, the photoluminescence kinetics undergoes substantial changes. The photoluminescence kinetics of the undoped quantum dots is adequately described by a sum of exponential relaxation relations, whereas the photoluminescence kinetics experimentally observed in the region of the impurity band of the copper-doped samples follows stretched exponential decay, with the average lifetimes 0.3-0.6 {mu}s at the photon energies in the range of 1.47-1.82 eV. The experimentally observed changes in the photoluminescence properties are attributed to transformation of radiative centers in the quantum dots when doped with copper atoms.

  1. Colloidally stable selenium@copper selenide core@shell nanoparticles as selenium source for manufacturing of copper-indium-selenide solar cells.

    PubMed

    Dong, Hailong; Quintilla, Aina; Cemernjak, Marco; Popescu, Radian; Gerthsen, Dagmar; Ahlswede, Erik; Feldmann, Claus

    2014-02-01

    Selenium nanoparticles with diameters of 100-400nm are prepared via hydrazine-driven reduction of selenious acid. The as-prepared amorphous, red selenium (a-Se) particles were neither a stable phase nor were they colloidally stable. Due to phase transition to crystalline (trigonal), grey selenium (t-Se) at or even below room temperature, the particles merged rapidly and recrystallized as micronsized crystal needles. As a consequence, such Se particles were not suited for layer deposition and as a precursor to manufacture thin-film CIS (copper indium selenide/CuInSe2) solar cells. To overcome this restriction, Se@CuSe core@shell particles are presented here. For these Se@CuSe core@shell nanoparticles, the phase transition a-Se→t-Se is shifted to temperatures higher than 100°C. Moreover, a spherical shape of the particles is retained even after phase transition. Composition and structure of the Se@CuSe core@shell nanostructure are evidenced by electron microscopy (SEM/STEM), DLS, XRD, FT-IR and line-scan EDXS. As a conceptual study, the newly formed Se@CuSe core@shell nanostructures with CuSe acting as a protecting layer to increase the phase-transition temperature and to improve the colloidal stability were used as a selenium precursor for manufacturing of thin-film CIS solar cells and already lead to conversion efficiencies up to 3%.

  2. Investigation of copper indium gallium selenide material growth by selenization of metallic precursors

    NASA Astrophysics Data System (ADS)

    Han, Junfeng; Liao, Cheng; Jiang, Tao; Xie, Huamu; Zhao, Kui; Besland, M.-P.

    2013-11-01

    We report a study of copper indium gallium selenide (CIGS) thin film growth in the annealing process at temperature range from 120 °C to 600 °C. Thin films were prepared by sputtering metal precursors and subsequent selenization process. Surface morphologies of thin films were observed by using high resolution field emission scanning electron microscopy (FESEM). Phases in quaternary systems Cu-In-Ga-Se were investigated by X-ray diffraction (XRD). Evolution of crystalline structure in the film surface was studied by Raman spectra. A possible reaction path from metallic precursors to a single CIGS phase was obtained by merging all results of SEM, XRD and Raman. Above 210 °C, selenium reacted with Cu and In to form binary selenide. CuSe crystalline platelets were observed clearly in the film surfaces. When temperature was reaching 380 °C, Cu2-xSe and InSe reacted with excess Se to form CuInSe2 (CIS) and contributed to the grain growth. Above 410 °C, Ga-rich phase was detected in the films. With increased temperature, Ga diffused into CIS crystalline lattices. Finally, at 600 °C, a single phase of Cu-In-Ga-Se quaternary system was formed. A large number of triangular and hexagonal structures were observed in the film due to a re-crystalline process at a high annealing temperature.

  3. Copper Selenide Nanosnakes: Bovine Serum Albumin-Assisted Room Temperature Controllable Synthesis and Characterization

    PubMed Central

    2010-01-01

    Herein we firstly reported a simple, environment-friendly, controllable synthetic method of CuSe nanosnakes at room temperature using copper salts and sodium selenosulfate as the reactants, and bovine serum albumin (BSA) as foaming agent. As the amounts of selenide ions (Se2−) released from Na2SeSO3 in the solution increased, the cubic and snake-like CuSe nanostructures were formed gradually, the cubic nanostructures were captured by the CuSe nanosnakes, the CuSe nanosnakes grew wider and longer as the reaction time increased. Finally, the cubic CuSe nanostructures were completely replaced by BSA–CuSe nanosnakes. The prepared BSA–CuSe nanosnakes exhibited enhanced biocompatibility than the CuSe nanocrystals, which highly suggest that as-prepared BSA–CuSe nanosnakes have great potentials in applications such as biomedical engineering. PMID:20672034

  4. Copper Selenide Nanosnakes: Bovine Serum Albumin-Assisted Room Temperature Controllable Synthesis and Characterization

    NASA Astrophysics Data System (ADS)

    Huang, Peng; Kong, Yifei; Li, Zhiming; Gao, Feng; Cui, Daxiang

    2010-06-01

    Herein we firstly reported a simple, environment-friendly, controllable synthetic method of CuSe nanosnakes at room temperature using copper salts and sodium selenosulfate as the reactants, and bovine serum albumin (BSA) as foaming agent. As the amounts of selenide ions (Se2-) released from Na2SeSO3 in the solution increased, the cubic and snake-like CuSe nanostructures were formed gradually, the cubic nanostructures were captured by the CuSe nanosnakes, the CuSe nanosnakes grew wider and longer as the reaction time increased. Finally, the cubic CuSe nanostructures were completely replaced by BSA-CuSe nanosnakes. The prepared BSA-CuSe nanosnakes exhibited enhanced biocompatibility than the CuSe nanocrystals, which highly suggest that as-prepared BSA-CuSe nanosnakes have great potentials in applications such as biomedical engineering.

  5. Copper Selenide Nanocrystals as a High Performance, Solution Processed Thermoelectric Material

    NASA Astrophysics Data System (ADS)

    Forster, Jason; Lynch, Jared; Coates, Nelson; Sahu, Ayaskanta; Liu, Jun; Cahill, David; Urban, Jeff

    Nano-structuring a thermoelectric material often results in enhanced performance due to a decrease in the materials' thermal conductivity. Traditional nano-structuring techniques involve ball milling a bulk material followed by spark plasma sintering, a very energy intensive process. In this talk, we will describe the development of a self-assembled, high-performing, nano-structured thin film based on copper selenide nanocrystals. Mild thermal annealing of these films results in concurrent increases in the Seebeck coefficient and electrical conductivity. We are able to achieve power factors at room temperature that are as high as the best spark plasma sintered materials. These solution-processed films have potential applications as conformal, flexible materials for thermoelectric power generation.

  6. Copper selenide nanosnakes: bovine serum albumin-assisted room temperature controllable synthesis and characterization.

    PubMed

    Huang, Peng; Kong, Yifei; Li, Zhiming; Gao, Feng; Cui, Daxiang

    2010-04-03

    Herein we firstly reported a simple, environment-friendly, controllable synthetic method of CuSe nanosnakes at room temperature using copper salts and sodium selenosulfate as the reactants, and bovine serum albumin (BSA) as foaming agent. As the amounts of selenide ions (Se2-) released from Na2SeSO3 in the solution increased, the cubic and snake-like CuSe nanostructures were formed gradually, the cubic nanostructures were captured by the CuSe nanosnakes, the CuSe nanosnakes grew wider and longer as the reaction time increased. Finally, the cubic CuSe nanostructures were completely replaced by BSA-CuSe nanosnakes. The prepared BSA-CuSe nanosnakes exhibited enhanced biocompatibility than the CuSe nanocrystals, which highly suggest that as-prepared BSA-CuSe nanosnakes have great potentials in applications such as biomedical engineering.

  7. Hydrothermal synthesis of copper selenides with controllable phases and morphologies from an ionic liquid precursor

    NASA Astrophysics Data System (ADS)

    Liu, Xiaodi; Duan, Xiaochuan; Peng, Peng; Zheng, Wenjun

    2011-12-01

    Cu2-xSe nanocrystals and CuSe nanoflakes are successfully synthesized through a convenient hydrothermal method from an ionic liquid precursor 1-n-butyl-3-ethylimidazolium methylselenite ([BMIm][SeO2(OCH3)]). The phases and morphologies of the copper selenides can be controlled by simply changing the atom ratio of Cu/Se in the reactants and reaction temperature. Furthermore, it is found that the [BMIm][SeO2(OCH3)] not only serves as Se source but also has influence on the shapes of CuSe nanoflakes. The adsorption of alkyl imidazolium rings ([BMIm]+) onto the (0001) facets of covellite CuSe prohibits the growth in the [0001] direction, and CuSe nuclei growth mainly processes along the six symmetric directions (+/-[01&cmb.macr;11], +/-[101&cmb.macr;1&cmb.macr;], and +/-[1&cmb.macr;100]) to form flakelike CuSe. The obtained copper selenides are characterized by XRD, SEM, EDS, XPS, TEM, and HRTEM. The results indicate that the Cu2-xSe nanocrystals are nearly spherical particles with an average diameter of about 20 nm, the hexagonal CuSe nanoflakes are single crystals with an edge length of 100-400 nm and a thickness of 25-50 nm. The potential formation mechanism of the copper selenides is also proposed.Cu2-xSe nanocrystals and CuSe nanoflakes are successfully synthesized through a convenient hydrothermal method from an ionic liquid precursor 1-n-butyl-3-ethylimidazolium methylselenite ([BMIm][SeO2(OCH3)]). The phases and morphologies of the copper selenides can be controlled by simply changing the atom ratio of Cu/Se in the reactants and reaction temperature. Furthermore, it is found that the [BMIm][SeO2(OCH3)] not only serves as Se source but also has influence on the shapes of CuSe nanoflakes. The adsorption of alkyl imidazolium rings ([BMIm]+) onto the (0001) facets of covellite CuSe prohibits the growth in the [0001] direction, and CuSe nuclei growth mainly processes along the six symmetric directions (+/-[01&cmb.macr;11], +/-[101&cmb.macr;1&cmb.macr;], and +/-[1

  8. Electrochemical synthesis and optical characterization of copper selenide nanowire arrays within the alumina pores

    NASA Astrophysics Data System (ADS)

    Jagminas, A.; Juškėnas, R.; Gailiūtė, I.; Statkutė, G.; Tomašiūnas, R.

    2006-09-01

    By choosing an appropriate aqueous solution containing CuSO 4, H 2SeO 3, MgSO 4, and H 2SO 4 the suitable composition for two- or one-phase copper selenide deposition within the alumina pores under alternating current (AC) electrolysis conditions was created. X-ray diffraction spectra recorded within 15-55° 2 Θ range revealed fabrication of Cu 3Se 2+Cu 2-xSe or almost pure Cu 2-xSe crystalline material. The compositional and morphological studies using XRD, EDX, SEM, and TEM techniques show fabrication of nearly pure Cu 2-xSe with some deficiency of copper, say, Cu 1.75Se, nanowires in length up to several microns when the selenious acid to copper-ion ratio is close to 1:2 and pH of the bath is <1.25. The fundamental absorption spectrum for this nanostructured material was shown to be formed by allowed direct and indirect interband transitions with the evaluated energy band gaps 2.3 and 1.1 eV, respectively.

  9. CONTROL OF LASER RADIATION PARAMETERS: Passive laser Q switches made of glass doped with oxidised nanoparticles of copper selenide

    NASA Astrophysics Data System (ADS)

    Yumashev, K. V.

    2000-01-01

    Passive Q switching of Nd3+:YAG (λ = 1060 nm) and YAlO3:Nd3+ (1340 nm) lasers, as well as of an Er3+ (1540 nm) glass laser was realised by using glass doped with oxidised nanoparticles of copper selenide. Nonlinear optical properties of the nanoparticles (radius of 25 nm) in a glass matrix were studied by the picosecond absorption spectroscopy technique.

  10. Near-IR absorption saturation and mechanism of picosecond recovery dynamics of copper selenide nanostructured via alumina

    NASA Astrophysics Data System (ADS)

    Statkutė, G.; Mikulskas, I.; Tomašiùnas, R.; Jagminas, A.

    2009-06-01

    Absorption saturation at 1.064 μm wavelength in Cu2-xSe material nanostructured by means of an original method—formation and hosting in an array of electrochemically grown alumina voids—was investigated. Columnlike channels provide growth of copper selenide in a shape of nanowire with a fixed diameter. Experimental results obtained from measuring nanowires of various diameters (∅10, 15, 20, and 70 nm) revealed that the ∅20 nm case is most efficient for absorption saturation, manifesting highest optical modulation depth and lowest interlevel transition rate evaluated. A model to analyze the conditions for absorption saturation and absorption recovery dynamics was developed. Depending on pump intensity the nonmonotonous increase in recovery time for the highest applied values was interpreted as filling up of states at an intermediate energy level. From modeling, important material science parameters, such as concentration of resonant and trapping/recombination states, interlevel transition rate, capture time, characteristic for copper selenide, have been evaluated and compared for different samples. Finally, the consequence of the model to a working copper selenide energy level scheme was considered.

  11. Highly Luminescent, Size- and Shape-Tunable Copper Indium Selenide Based Colloidal Nanocrystals.

    PubMed

    Yarema, Olesya; Bozyigit, Deniz; Rousseau, Ian; Nowack, Lea; Yarema, Maksym; Heiss, Wolfgang; Wood, Vanessa

    2013-09-24

    We report a simple, high-yield colloidal synthesis of copper indium selenide nanocrystals (CISe NCs) based on a silylamide-promoted approach. The silylamide anions increase the nucleation rate, which results in small-sized NCs exhibiting high luminescence and constant NC stoichiometry and crystal structure regardless of the NC size and shape. In particular, by systematically varying synthesis time and temperature, we show that the size of the CISe NCs can be precisely controlled to be between 2.7 and 7.9 nm with size distributions down to 9-10%. By introducing a specific concentration of silylamide-anions in the reaction mixture, the shape of CISe NCs can be preselected to be either spherical or tetrahedral. Optical properties of these CISe NCs span from the visible to near-infrared region with peak luminescence wavelengths of 700 to 1200 nm. The luminescence efficiency improves from 10 to 15% to record values of 50-60% by overcoating as-prepared CISe NCs with ZnSe or ZnS shells, highlighting their potential for applications such as biolabeling and solid state lighting.

  12. Influence of different deposition potential on the structural and optical properties of copper selenide nanowires

    NASA Astrophysics Data System (ADS)

    Kaur, Harmanmeet; Kaur, Jaskiran; Singh, Lakhwant

    2016-09-01

    In this paper, nanowires were successfully fabricated from the aqueous solution containing 0.2 M/l CuSO4.5H2O, 0.1 M/l SeO2, 1 g/l PVP and a few drops of H2SO4 in Milli-Q water using electrodeposition technique at room temperature. Influence of different deposition potential on structural and optical properties of copper selenide nanowires has been investigated here. Morphological, structural and optical properties were monitored through field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD) and UV-visible 1800 spectrophotometer. From the XRD analysis, it was found that the stoichiometric (CuSe) nanowires are formed at deposition potential (-0.6 V) and (+0.6 V). Band gap of nanowires were found to be maximum around 3.13 eV for deposition potential (-0.8 V) and minimum of 2.81 eV for deposition potential (-0.6 V).

  13. Point contacts at the copper-indium-gallium-selenide interface—A theoretical outlook

    NASA Astrophysics Data System (ADS)

    Bercegol, Adrien; Chacko, Binoy; Klenk, Reiner; Lauermann, Iver; Lux-Steiner, Martha Ch.; Liero, Matthias

    2016-04-01

    For a long time, it has been assumed that recombination in the space-charge region of copper-indium-gallium-selenide (CIGS) is dominant, at least in high efficiency solar cells with low band gap. The recent developments like potassium fluoride post deposition treatment and point-contact junction may call this into question. In this work, a theoretical outlook is made using three-dimensional simulations to investigate the effect of point-contact openings through a passivation layer on CIGS solar cell performance. A large set of solar cells is modeled under different scenarios for the charged defect levels and density, radius of the openings, interface quality, and conduction band offset. The positive surface charge created by the passivation layer induces band bending and this influences the contact (CdS) properties, making it beneficial for the open circuit voltage and efficiency, and the effect is even more pronounced when coverage area is more than 95%, and also makes a positive impact on the device performance, even in the presence of a spike at CIGS/CdS heterojunction.

  14. Field Effect Transistors Using Atomically Thin Layers of Copper Indium Selenide (CuInSe)

    NASA Astrophysics Data System (ADS)

    Patil, Prasanna; Ghosh, Sujoy; Wasala, Milinda; Lei, Sidong; Vajtai, Robert; Ajayan, Pulickel; Talapatra, Saikat

    We will report fabrication of field-effect transistors (FETs) using few-layers of Copper Indium Selenide (CuInSe) flakes exfoliated from crystals grown using chemical vapor transport technique. Our transport measurements indicate n-type FET with electron mobility µ ~ 3 cm2 V-1 s-1 at room temperature when Silicon dioxide (SiO2) is used as a back gate. Mobility can be further increased significantly when ionic liquid 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) is used as top gate. Similarly subthreshold swing can be further improved from 103 V/dec to 0.55 V/dec by using ionic liquid as a top gate. We also found ON/OFF ratio of ~ 102 for both top and back gate. Comparison between ionic liquid top gate and SiO2 back gate will be presented and discussed. This work is supported by the U.S. Army Research Office through a MURI Grant # W911NF-11-1-0362.

  15. Liquid-like cationic sub-lattice in copper selenide clusters

    NASA Astrophysics Data System (ADS)

    White, Sarah L.; Banerjee, Progna; Jain, Prashant K.

    2017-02-01

    Super-ionic solids, which exhibit ion mobilities as high as those in liquids or molten salts, have been employed as solid-state electrolytes in batteries, improved thermoelectrics and fast-ion conductors in super-capacitors and fuel cells. Fast-ion transport in many of these solids is supported by a disordered, `liquid-like' sub-lattice of cations mobile within a rigid anionic sub-lattice, often achieved at high temperatures or pressures via a phase transition. Here we show that ultrasmall clusters of copper selenide exhibit a disordered cationic sub-lattice under ambient conditions unlike larger nanocrystals, where Cu+ ions and vacancies form an ordered super-structure similar to the bulk solid. The clusters exhibit an unusual cationic sub-lattice arrangement wherein octahedral sites, which serve as bridges for cation migration, are stabilized by compressive strain. The room-temperature liquid-like nature of the Cu+ sub-lattice combined with the actively tunable plasmonic properties of the Cu2Se clusters make them suitable as fast electro-optic switches.

  16. A Solution Processable High-Performance Thermoelectric Copper Selenide Thin Film.

    PubMed

    Lin, Zhaoyang; Hollar, Courtney; Kang, Joon Sang; Yin, Anxiang; Wang, Yiliu; Shiu, Hui-Ying; Huang, Yu; Hu, Yongjie; Zhang, Yanliang; Duan, Xiangfeng

    2017-03-29

    A solid-state thermoelectric device is attractive for diverse technological areas such as cooling, power generation and waste heat recovery with unique advantages of quiet operation, zero hazardous emissions, and long lifetime. With the rapid growth of flexible electronics and miniature sensors, the low-cost flexible thermoelectric energy harvester is highly desired as a potential power supply. Herein, a flexible thermoelectric copper selenide (Cu2 Se) thin film, consisting of earth-abundant elements, is reported. The thin film is fabricated by a low-cost and scalable spin coating process using ink solution with a truly soluble precursor. The Cu2 Se thin film exhibits a power factor of 0.62 mW/(m K(2) ) at 684 K on rigid Al2 O3 substrate and 0.46 mW/(m K(2) ) at 664 K on flexible polyimide substrate, which is much higher than the values obtained from other solution processed Cu2 Se thin films (<0.1 mW/(m K(2) )) and among the highest values reported in all flexible thermoelectric films to date (≈0.5 mW/(m K(2) )). Additionally, the fabricated thin film shows great promise to be integrated with the flexible electronic devices, with negligible performance change after 1000 bending cycles. Together, the study demonstrates a low-cost and scalable pathway to high-performance flexible thin film thermoelectric devices from relatively earth-abundant elements.

  17. Liquid-like cationic sub-lattice in copper selenide clusters

    PubMed Central

    White, Sarah L.; Banerjee, Progna; Jain, Prashant K.

    2017-01-01

    Super-ionic solids, which exhibit ion mobilities as high as those in liquids or molten salts, have been employed as solid-state electrolytes in batteries, improved thermoelectrics and fast-ion conductors in super-capacitors and fuel cells. Fast-ion transport in many of these solids is supported by a disordered, ‘liquid-like' sub-lattice of cations mobile within a rigid anionic sub-lattice, often achieved at high temperatures or pressures via a phase transition. Here we show that ultrasmall clusters of copper selenide exhibit a disordered cationic sub-lattice under ambient conditions unlike larger nanocrystals, where Cu+ ions and vacancies form an ordered super-structure similar to the bulk solid. The clusters exhibit an unusual cationic sub-lattice arrangement wherein octahedral sites, which serve as bridges for cation migration, are stabilized by compressive strain. The room-temperature liquid-like nature of the Cu+ sub-lattice combined with the actively tunable plasmonic properties of the Cu2Se clusters make them suitable as fast electro-optic switches. PMID:28216615

  18. Liquid-like cationic sub-lattice in copper selenide clusters.

    PubMed

    White, Sarah L; Banerjee, Progna; Jain, Prashant K

    2017-02-20

    Super-ionic solids, which exhibit ion mobilities as high as those in liquids or molten salts, have been employed as solid-state electrolytes in batteries, improved thermoelectrics and fast-ion conductors in super-capacitors and fuel cells. Fast-ion transport in many of these solids is supported by a disordered, 'liquid-like' sub-lattice of cations mobile within a rigid anionic sub-lattice, often achieved at high temperatures or pressures via a phase transition. Here we show that ultrasmall clusters of copper selenide exhibit a disordered cationic sub-lattice under ambient conditions unlike larger nanocrystals, where Cu(+) ions and vacancies form an ordered super-structure similar to the bulk solid. The clusters exhibit an unusual cationic sub-lattice arrangement wherein octahedral sites, which serve as bridges for cation migration, are stabilized by compressive strain. The room-temperature liquid-like nature of the Cu(+) sub-lattice combined with the actively tunable plasmonic properties of the Cu2Se clusters make them suitable as fast electro-optic switches.

  19. Impact of atmospheric species on copper indium gallium selenide solar cell stability: an overview

    NASA Astrophysics Data System (ADS)

    Theelen, Mirjam

    2016-01-01

    An overview of the measurement techniques and results of studies on the stability of copper indium gallium selenide (CIGS) solar cells and their individual layers in the presence of atmospheric species is presented: in these studies, Cu(In,Ga)Se2 solar cells, their molybdenum back contact, and their ZnO:Al front contact were exposed to liquid water purged with gases from the atmosphere, like carbon dioxide (CO2), oxygen (O2), nitrogen (N2), and air. The samples were analyzed before, during, and after exposure in order to define their stability under these conditions. The complete CIGS solar cells as well as the ZnO:Al front contact degraded rapidly when exposed to H2O combined with CO2, while they were relatively stable in H2O purged with O2 or N2. This was caused by either degradation of the grain boundaries in the ZnO:Al film or by the dissolution of part of this film. Uncovered molybdenum films, on the other hand, oxidized rapidly in the presence of H2O and O2, while they were more stable in the presence of H2O with N2 and/or CO2.

  20. Highly Luminescent, Size- and Shape-Tunable Copper Indium Selenide Based Colloidal Nanocrystals

    PubMed Central

    2013-01-01

    We report a simple, high-yield colloidal synthesis of copper indium selenide nanocrystals (CISe NCs) based on a silylamide-promoted approach. The silylamide anions increase the nucleation rate, which results in small-sized NCs exhibiting high luminescence and constant NC stoichiometry and crystal structure regardless of the NC size and shape. In particular, by systematically varying synthesis time and temperature, we show that the size of the CISe NCs can be precisely controlled to be between 2.7 and 7.9 nm with size distributions down to 9–10%. By introducing a specific concentration of silylamide-anions in the reaction mixture, the shape of CISe NCs can be preselected to be either spherical or tetrahedral. Optical properties of these CISe NCs span from the visible to near-infrared region with peak luminescence wavelengths of 700 to 1200 nm. The luminescence efficiency improves from 10 to 15% to record values of 50–60% by overcoating as-prepared CISe NCs with ZnSe or ZnS shells, highlighting their potential for applications such as biolabeling and solid state lighting. PMID:24748721

  1. Highly efficient copper-zinc-tin-selenide (CZTSe) solar cells by electrodeposition.

    PubMed

    Jeon, Jong-Ok; Lee, Kee Doo; Seul Oh, Lee; Seo, Se-Won; Lee, Doh-Kwon; Kim, Honggon; Jeong, Jeung-hyun; Ko, Min Jae; Kim, BongSoo; Son, Hae Jung; Kim, Jin Young

    2014-04-01

    Highly efficient copper-zinc-tin-selenide (Cu2ZnSnSe4 ; CZTSe) thin-film solar cells are prepared via the electrodepostion technique. A metallic alloy precursor (CZT) film with a Cu-poor, Zn-rich composition is directly deposited from a single aqueous bath under a constant current, and the precursor film is converted to CZTSe by annealing under a Se atmosphere at temperatures ranging from 400 °C to 600 °C. The crystallization of CZTSe starts at 400 °C and is completed at 500 °C, while crystal growth continues at higher temperatures. Owing to compromises between enhanced crystallinity and poor physical properties, CZTSe thin films annealed at 550 °C exhibit the best and most-stable device performances, reaching up to 8.0 % active efficiency; among the highest efficiencies for CZTSe thin-film solar cells prepared by electrodeposition. Further analysis of the electronic properties and a comparison with another state-of-the-art device prepared from a hydrazine-based solution, suggests that the conversion efficiency can be further improved by optimizing parameters such as film thickness, antireflection coating, MoSe2 formation, and p-n junction properties.

  2. Exploring the doping effects of copper on thermoelectric properties of lead selenide

    NASA Astrophysics Data System (ADS)

    Gayner, Chhatrasal; Sharma, Raghunandan; Mallik, Iram; Das, Malay K.; Kar, Kamal K.

    2016-07-01

    In this work, we have explored the effect of dopant concentration (copper (Cu)) on the thermoelectric performance of Cu doped lead selenide (Pb1-x Cu x Se (0  ⩽  x  ⩽  0.1)). With increasing the dopant concentration, sign inversion of majority charge carriers takes place for x  ⩾  0.04 due to the donor behaviour of Cu in the P-type pristine PbSe. The room temperature Seebeck coefficients of Pb1-x Cu x Se with x  =  0.01, 0.02, 0.04, 0.06 and 0.08 are observed to be 233, 337, -473.7, -392.5 and  -257.6 μV K-1, respectively as compared to that of 186.4 μV K-1 of the pristine PbSe. This increment in Seebeck coefficient is the result of low carrier concentration and is not related to the resonance states created by Cu dopant. At room temperature, the lattice thermal conductivity of pristine PbSe is 0.52 W m-1 K-1 while for Cu doped PbSe, it varies from 0.8 to 1.1 W m-1 K-1. Finally, with ZT of ~0.59 and power factor of ~700 at 500 K, Pb0.98Cu0.02Se exhibits the highest thermoelectric performance among the studied Pb1-x Cu x Se systems. Owing to the high ZT and power factor, a single thermoelement of Pb0.98Cu0.02Se exhibits thermovoltage of  >100 mV at a temperature gradient of 200 °C.

  3. Ecotoxicological assessment of solar cell leachates: Copper indium gallium selenide (CIGS) cells show higher activity than organic photovoltaic (OPV) cells.

    PubMed

    Brun, Nadja Rebecca; Wehrli, Bernhard; Fent, Karl

    2016-02-01

    Despite the increasing use of photovoltaics their potential environmental risks are poorly understood. Here, we compared ecotoxicological effects of two thin-film photovoltaics: established copper indium gallium selenide (CIGS) and organic photovoltaic (OPV) cells. Leachates were produced by exposing photovoltaics to UV light, physical damage, and exposure to environmentally relevant model waters, representing mesotrophic lake water, acidic rain, and seawater. CIGS cell leachates contained 583 μg L(-1) molybdenum at lake water, whereas at acidic rain and seawater conditions, iron, copper, zinc, molybdenum, cadmium, silver, and tin were present up to 7219 μg L(-1). From OPV, copper (14 μg L(-1)), zinc (87 μg L(-1)) and silver (78 μg L(-1)) leached. Zebrafish embryos were exposed until 120 h post-fertilization to these extracts. CIGS leachates produced under acidic rain, as well as CIGS and OPV leachates produced under seawater conditions resulted in a marked hatching delay and increase in heart edema. Depending on model water and solar cell, transcriptional alterations occurred in genes involved in oxidative stress (cat), hormonal activity (vtg1, ar), metallothionein (mt2), ER stress (bip, chop), and apoptosis (casp9). The effects were dependent on the concentrations of cationic metals in leachates. Addition of ethylenediaminetetraacetic acid protected zebrafish embryos from morphological and molecular effects. Our study suggests that metals leaching from damaged CIGS cells, may pose a potential environmental risk.

  4. Highly Efficient Copper-Indium-Selenide Quantum Dot Solar Cells: Suppression of Carrier Recombination by Controlled ZnS Overlayers.

    PubMed

    Kim, Jae-Yup; Yang, Jiwoong; Yu, Jung Ho; Baek, Woonhyuk; Lee, Chul-Ho; Son, Hae Jung; Hyeon, Taeghwan; Ko, Min Jae

    2015-11-24

    Copper-indium-selenide (CISe) quantum dots (QDs) are a promising alternative to the toxic cadmium- and lead-chalcogenide QDs generally used in photovoltaics due to their low toxicity, narrow band gap, and high absorption coefficient. Here, we demonstrate that the photovoltaic performance of CISe QD-sensitized solar cells (QDSCs) can be greatly enhanced simply by optimizing the thickness of ZnS overlayers on the QD-sensitized TiO2 electrodes. By roughly doubling the thickness of the overlayers compared to the conventional one, conversion efficiency is enhanced by about 40%. Impedance studies reveal that the thick ZnS overlayers do not affect the energetic characteristics of the photoanode, yet enhance the kinetic characteristics, leading to more efficient photovoltaic performance. In particular, both interfacial electron recombination with the electrolyte and nonradiative recombination associated with QDs are significantly reduced. As a result, our best cell yields a conversion efficiency of 8.10% under standard solar illumination, a record high for heavy metal-free QD solar cells to date.

  5. Thin-film copper indium gallium selenide solar cell based on low-temperature all-printing process.

    PubMed

    Singh, Manjeet; Jiu, Jinting; Sugahara, Tohru; Suganuma, Katsuaki

    2014-09-24

    In the solar cell field, development of simple, low-cost, and low-temperature fabrication processes has become an important trend for energy-saving and environmental issues. Copper indium gallium selenide (CIGS) solar cells have attracted much attention due to the high absorption coefficient, tunable band gap energy, and high efficiency. However, vacuum and high-temperature processing in fabrication of solar cells have limited the applications. There is a strong need to develop simple and scalable methods. In this work, a CIGS solar cell based on all printing steps and low-temperature annealing is developed. CIGS absorber thin film is deposited by using dodecylamine-stabilized CIGS nanoparticle ink followed by printing buffer layer. Silver nanowire (AgNW) ink and sol-gel-derived ZnO precursor solution are used to prepare a highly conductive window layer ZnO/[AgNW/ZnO] electrode with a printing method that achieves 16 Ω/sq sheet resistance and 94% transparency. A CIGS solar cell based on all printing processes exhibits efficiency of 1.6% with open circuit voltage of 0.48 V, short circuit current density of 9.7 mA/cm(2), and fill factor of 0.34 for 200 nm thick CIGS film, fabricated under ambient conditions and annealed at 250 °C.

  6. Influence of growth and photocatalytic properties of copper selenide (CuSe) nanoparticles using reflux condensation method

    NASA Astrophysics Data System (ADS)

    Sonia, S.; Kumar, P. Suresh; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.

    2013-10-01

    Influence of reaction conditions on the synthesis of copper selenide (CuSe) nanoparticles and their photo degradation activity is studied. Nearly monodispersed uniform size (23-44 nm) nanoparticles are synthesized by varying the reaction conditions using reflux condensation method. The obtained nanoparticles are characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and UV-visible absorption spectroscopy. The X-ray diffraction analysis of the sample shows the formation of nanoparticles with hexagonal CuSe structure. The result indicates that on increasing the reaction time from 4 to 12 h, the particle size decreases from 44 to 23 nm, but an increase in the reaction temperature increases the particle size. The calculated band gap Eg is ranging from 2.34 to 3.05 eV which is blue shifted from the bulk CuSe (2.2 eV). The photocatalytic degradation efficiency of the CuSe nanoparticles on two organic dyes Methylene blue (MB) and Rhodamine-B (RhB) in aqueous solution under UV region is calculated as 76 and 87% respectively.

  7. Liquid precursor for deposition of copper selenide and method of preparing the same

    DOEpatents

    Curtis, Calvin J.; Miedaner, Alexander; Franciscus Antonius Maria Van Hest, Marinus; Ginley, David S.; Hersh, Peter A.; Eldada, Louay; Stanbery, Billy J.

    2015-09-08

    Liquid precursors containing copper and selenium suitable for deposition on a substrate to form thin films suitable for semiconductor applications are disclosed. Methods of preparing such liquid precursors and methods of depositing a precursor on a substrate are also disclosed.

  8. Thin film metallic glass as a diffusion barrier for copper indium gallium selenide solar cell on stainless steel substrate: A feasibility study

    NASA Astrophysics Data System (ADS)

    Diyatmika, Wahyu; Xue, Lingjun; Lin, Tai-Nan; Chang, Chia-wen; Chu, Jinn P.

    2016-08-01

    The feasibility of using Zr53.5Cu29.1Al6.5Ni10.9 thin-film metallic glass (TFMG) as a diffusion barrier for copper indium gallium selenide (CIGS) solar cells on stainless steel (SS) is investigated. The detrimental Fe diffusion from SS into CIGS is found to be effectively hindered by the introduction of a 70-nm-thick TFMG barrier; the cell performance is thus improved. Compared with the 2.73% of CIGS on bare SS, a higher efficiency of 5.25% is obtained for the cell with the Zr52Cu32Al9Ni7 TFMG barrier.

  9. Bath Parameter Dependence of Chemically-Deposited Copper Selenide Thin Film

    NASA Astrophysics Data System (ADS)

    Al-Mamun; Islam, A. B. M. O.

    In this article, a low cost chemical bath deposition (CBD) technique has been used for the preparation of Cu2-xSe thin films on to glass substrate. Different thin films (0.2-0.6 μm) were prepared by adjusting the bath parameter like concentration of ammonia, deposition time, temperature of the solution, and the ratios of the mixing composition between copper and selenium in the reaction bath. From these studies, it reveals that at low concentration of ammonia or TEA, the terminal thicknesses of the films are less, which gradually increases with the increase of concentrations and then drop down at still higher concentrations. It has been found that complexing the Cu2+ ions with TEA first, and then addition of ammonia yields better results than the reverse process. The film thickness increases with the decrease of value x of Cu2-xSe.

  10. Infrared cadmium selenide photoconductor and process of making same

    SciTech Connect

    Faria, S.

    1987-02-17

    The process is described of making an infrared responsive cadmium selenide photoconductor comprising the steps of preparing a blend of cadmium selenide, copper-containing cadmium selenide mix and cadmium chloride, and firing the blend at a temperature of about 425/sup 0/C.

  11. Synthesis and structure determination of potassium copper selenide nanowires and solid-state supercapacitor application

    NASA Astrophysics Data System (ADS)

    Zhang, Kaiyou; Chen, Hong; Wang, Xue; Guo, Donglin; Hu, Chenguo; Wang, Shuxia; Sun, Junliang; Leng, Qiang

    2014-12-01

    The new ternary alkali metal copper chalcogenide KCu4Se8 nanowires with average length of 30 μm are synthesized using a modified composite-hydroxide mediated (M-CHM) approach. The prepared KCu4Se8 is characterized by XRD, EDS, FESEM and TEM analysis. The structure is determined by the newly developed Rotation Electron Diffraction technique. It is identified to be a body center tetragonal phase. The prepared KCu4Se8 is used to fabricate solid-state supercapacitors in which the thin film of the electrodes are made with pressure of 0 MPa, 5 MPa and 10 MPa, and their electrochemical properties are tested. It is found that 0 MPa supercapacitor displays best electrochemical performance and the specific capacitance of 25.3 F g-1 is obtained at the scan rate of 5 mV s-1. It also shows good long-term cycle property by recording 5000 cycles of galvanostatic charge/discharge operation. The specific capacitance can be enhanced to 93.7 F g-1 at the scan rate of 5 mV s-1 by coating 0.1 mg V2O5 nanowire on 0 MPa KCu4Se8 electrode.

  12. Three approaches to economical photovoltaics: Conformal copper sulfide , organic luminescent films, and lead selenide nanocrystal superlattices

    NASA Astrophysics Data System (ADS)

    Carbone, Ian A.

    Three routes to more efficient photovoltaics using conformal Cu2S, organic luminescent films, and nanocrystalline PbSe films are outlined below. Properties of these materials are investigated experimentally and numerically in separate studies. In the first study, chemical vapor deposition (CVD) processes were used to fabricate Cu2S using hydrogen sulfide and the metal-organic precursor, KI5. The alternating exposure of mesoporous TiO2 and planar ZnO to the two precursors resulted in films that penetrated porous structures and deposited at a constant rate of 0.08nm/cycle over the temperature range 150C-400°C. Sheet resistance and optical absorption measurements suggest the presence of a metallic copper-poor phase of less than 100nm thick forming at the Cu2S/substrate boundary. In a separate study, organic films doped with luminescent dyes were placed above CdTe/CdS solar cells to convert high energy photons to lower energies, better matched to the CdTe/CdS quantum efficiency peak. Efficiency improvements of up to 8.5% were obtained after optimizing dye concentration, dye chemistry, and the host material. Long-term stability tests show that the organic films are stable for at least 5000 hours under 1 sun illumination provided that the dye is encapsulated in an oxygen and water free environment. Finally, a Monte Carlo model was developed to simulate electron and hole transport in nanocrystalline PbSe films. Transport is carried out as a series of thermally activated tunneling events between neighboring sites on a cubic lattice. Each site, representing an individual nanocrystal, is assigned a size-dependent electronic structure, and the effects of crystal size, charging, inter-crystal coupling, and energetic disorder on electron and hole mobilities/conductivities are investigated. Results of simulated field effect measurements confirm that electron mobilities and conductivities increase by an order of magnitude when the average nanocrystal diameter is increased in the

  13. Growth and Characterization of the p-type Semiconductors Tin Sulfide and Bismuth Copper Oxy Selenide

    NASA Astrophysics Data System (ADS)

    Francis, Jason

    BiCuOSe and SnS are layered, moderate band gap (epsilon G ≈ 1 eV) semiconductors that exhibit intrinsic p type conductivity. Doping of BiCuOSe with Ca results in a slight expansion of the lattice and an increase of the hole concentration from 10 18 cm--3 to greater than 1020 cm --3. The large carrier density in undoped films is the result of copper vacancies. Mobility is unaffected by doping, remaining constant at 1.5 cm2V--1s--1 in both undoped and doped films, because the Bi-O layers serve as the source of carriers, while transport occurs within the Cu-Se layers. Bi possesses a 6s2 lone pair that was expected to hybridize with the oxygen p states at the top of the valence band, resulting in high hole mobility as compared to similar materials such as LaCuOSe, which lack this lone pair. However, both LaCuOSe and BiCuOSe have similar hole mobility. X-ray absorption and emission spectroscopy, combined with density functional theory calculations, reveal that the Bi 6 s states contribute deep within the valence band, forming bonding and anti-bonding states with O 2p at 11 eV and 3 eV below the valence band maximum, respectively. Hence, the Bi lone pair does not contribute at the top of the valence band and does not enhance the hole mobility. The Bi 6p states contribute at the bottom of the conduction band, resulting in a smaller band gap for BiCuOSe than LaCuOSe (1 eV vs. 3 eV). SnS is a potential photovoltaic absorber composed of weakly coupled layers stacked along the long axis. This weak coupling results in the formation of strongly oriented films on amorphous substrates. The optical band gap is 1.2 eV, in agreement with GW calculations. Absorption reaches 105 cm--1 within 0.5 eV of the band gap. The p type conduction arises from energetically favorable tin vacancies. Variation of growth conditions yields carrier densities of 1014 -- 1016 cm--3 and hole mobility of 7 -- 15 cm2V--1s--1. SnS was alloyed with rocksalt CaS, which was predicted to form a rocksalt

  14. A study on the optics of copper indium gallium (di)selenide (CIGS) solar cells with ultra-thin absorber layers.

    PubMed

    Xu, Man; Wachters, Arthur J H; van Deelen, Joop; Mourad, Maurice C D; Buskens, Pascal J P

    2014-03-10

    We present a systematic study of the effect of variation of the zinc oxide (ZnO) and copper indium gallium (di)selenide (CIGS) layer thickness on the absorption characteristics of CIGS solar cells using a simulation program based on finite element method (FEM). We show that the absorption in the CIGS layer does not decrease monotonically with its layer thickness due to interference effects. Ergo, high precision is required in the CIGS production process, especially when using ultra-thin absorber layers, to accurately realize the required thickness of the ZnO, cadmium sulfide (CdS) and CIGS layer. We show that patterning the ZnO window layer can strongly suppress these interference effects allowing a higher tolerance in the production process.

  15. Template free-solvothermaly synthesized copper selenide (CuSe, Cu 2- xSe, β-Cu 2Se and Cu 2Se) hexagonal nanoplates from different precursors at low temperature

    NASA Astrophysics Data System (ADS)

    Kumar, Pushpendra; Singh, Kedar; Srivastava, O. N.

    2010-09-01

    Nonstoichiometric (Cu 2- xSe) and stoichiometric (CuSe, β-Cu 2Se and Cu 2Se) copper selenide hexagonal nanoplates have been synthesized using different general and convenient copper sources, e.g. copper chloride, copper sulphate, copper nitrate, copper acetate, elemental copper with elemental selenium, friendly ethylene glycol and hydrazine hydrate in a defined amount of water at 100 °C within 12 h adopting the solvothermal method. Phase analysis, purity and morphology of the product have been well studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray diffraction (EDAX) techniques. The structural and compositional analysis revealed that the products were of pure phase with corresponding atomic ratios. SEM, TEM and HRTEM analyses revealed that the nanoplates were in the range 200-450 nm and the as-prepared products were uniform and highly crystallized. The nanoplates consisted of {0 0 1} facets of top-bottom surfaces and {1 1 0} facets of the other six side surfaces. This new approach encompasses many advantages over the conventional solvothermal method in terms of product quality (better morphology control with high yield) and reaction conditions (lower temperatures). Copper selenide hexagonal nanoplates obtained by the described method could be potential building blocks to construct functional devices and solar cell. This work may open up a new rationale on designing the solution synthesis of nanostructures for materials possessing similar intrinsic crystal symmetry. On the basis of the carefully controlled experiments mentioned herein, a plausible formation mechanism of the hexagonal nanoplates was suggested and discussed. To the best of our knowledge, this is the first report on nonstoichiometric (Cu 2- xSe) as well as stoichiometric (CuSe, β-Cu 2Se and Cu 2Se) copper selenide hexagonal nanoplates with

  16. Synthesis and structure of an "iron-doped" copper selenide cluster molecule: [Cu30Fe2Se6(SePh)24(dppm)4].

    PubMed

    Eichhöfer, Andreas; Olkowska-Oetzel, Jolanta; Fenske, Dieter; Fink, Karin; Mereacre, Valeriu; Powell, Annie K; Buth, Gernot

    2009-09-21

    CuCl and bis(diphenylphosphanyl)methane (dppm) react in the presence of small amounts of FeCl(3) with PhSeSiMe(3) and Se(SiMe(3))(2) to yield [Cu(30)Fe(2)Se(6)(SePh)(24)(dppm)(4)]. The crystal structure of the compound was determined by single-crystal X-ray analysis to give a mixed copper selenide/selenolate cluster molecule of a new structural type incorporating two central iron atoms. The formal oxidation state of the iron atoms was determined by Mössbauer spectroscopy to be +3, in agreement with quantum chemical calculations and modeling of the magnetic data. In addition, Mössbauer studies show no magnetic hyperfine structure in zero field, and the magnetically perturbed spectrum displays a pattern typical for a diamagnetic species in a transverse field, suggesting a singlet ground state. However, the inclusion of the iron atoms has a distinct influence on the optical properties of the compound compared to similar clusters containing only copper and selenium atoms.

  17. Characterization of copper selenide thin film hole-injection layers deposited at room temperature for use with p-type organic semiconductors

    NASA Astrophysics Data System (ADS)

    Hiramatsu, Hidenori; Koizumi, Ikue; Kim, Ki-Beom; Yanagi, Hiroshi; Kamiya, Toshio; Hirano, Masahiro; Matsunami, Noriaki; Hosono, Hideo

    2008-12-01

    Copper selenide, CuxSe(x ˜2), was examined as a hole-injection layer for low-temperature organic devices. Crystalline CuxSe films grown at room temperature with atomically flat surfaces exhibited metallic conduction with a high electrical conductivity of 4.5×103 S/cm, a hole concentration of 1.4×1022 cm-3, and a mobility of 2.0 cm2/(V s). Analysis of the free carrier absorption using the Drude model estimated the effective mass of a hole as 1.0me. Photoemission spectroscopy measurements of the interfaces between CuxSe and organic hole transport layers, N ,N'-bis(naphthalen-1-yl)-N ,N'-bis(phenyl) benzidine (NPB) and copper phthalocyanine (CuPc), verified that the hole-injection barriers of these interfaces (0.4 eV for NPB and 0.3 eV for CuPc) are smaller than that of a conventional indium tin oxide (ITO) hole-injection electrode/NPB interface (0.6 eV) but are comparable to that of an ITO electrode/CuPc interface (0.3 eV). Hole-only devices using the CuxSe layer as a hole-injection anode exhibited very low threshold voltages (0.4-0.5 V) and nearly Ohmic characteristics. The NPB layer on the CuxSe layer was found to be highly doped at 1017-1019 cm-3, probably due to copper diffusion, while the CuPc layer is nearly intrinsic with a doping concentration lower than 1015 cm-3. These results indicated that a CuxSe film combined with CuPc is a promising candidate for a low-voltage hole-injection anode or a buffer layer in low-temperature devices such as organic light-emitting diodes and thin film transistors.

  18. Formation of selenide, sulfide or mixed selenide-sulfide films on metal or metal coated substrates

    DOEpatents

    Eser, Erten; Fields, Shannon

    2012-05-01

    A process and composition for preventing cracking in composite structures comprising a metal coated substrate and a selenide, sulfide or mixed selenide sulfide film. Specifically, cracking is prevented in the coating of molybdenum coated substrates upon which a copper, indium-gallium diselenide (CIGS) film is deposited. Cracking is inhibited by adding a Se passivating amount of oxygen to the Mo and limiting the amount of Se deposited on the Mo coating.

  19. Lead-Sulfide-Selenide Quantum Dots and Gold-Copper Alloy Nanoparticles Augment the Light-Harvesting Ability of Solar Cells.

    PubMed

    Das, Aparajita; Deepa, Melepurath; Ghosal, Partha

    2017-01-10

    Lead-sulfide-selenide (PbSSe) quantum dots (QDs) and gold-copper (AuCu) alloy nanoparticles (NPs) were incorporated into a cadmium sulfide (CdS)/titanium oxide (TiO2 ) photoanode for the first time to achieve enhanced conversion of solar energy into electricity. PbSSe QDs with a band gap of 1.02 eV extend the light-harvesting range of the photoanode from the visible region to the near-infrared region. The conduction band (CB) edge of the PbSSe QDs is wedged between the CBs of TiO2 and CdS; this additional level coupled with the good electrical conductivity of the dots facilitate charge transport and collection, and a high power conversion efficiency (PCE) of 4.44 % is achieved for the champion cell with the TiO2 /PbSSe/CdS electrode. Upon including AuCu alloy NPs in the QD-sensitized electrodes, light absorption is enhance by plasmonic and light-scattering effects and also by the injection of hot electrons to the CBs of the QDs. Comparison of the incident photon-to-current conversion efficiency enhancement factors in addition to fluorescence decay and impedance studies reveal that the PbSSe QDs and AuCu alloy NPs promote charge injection to the current collector and increase the photogenerated charges produced, which thus enables the TiO2 /PbSSe/CdS/AuCu cell to deliver the highest PCE of 5.26 % among all the various photoanode compositions used.

  20. Alkylthiol-enabled Se powder dissolution in oleylamine at room temperature for the phosphine-free synthesis of copper-based quaternary selenide nanocrystals.

    PubMed

    Liu, Yi; Yao, Dong; Shen, Liang; Zhang, Hao; Zhang, Xindong; Yang, Bai

    2012-05-02

    Enhancement of Se solubility in organic solvents without the use of alkylphosphine ligands is the key for phosphine-free synthesis of selenide semiconductor nanocrystals (NCs). In this communication, we demonstrate the dissolution of elemental Se in oleylamine by alkylthiol reduction at room temperature, which generates soluble alkylammonium selenide. This Se precursor is highly reactive for hot-injection synthesis of selenide semiconductor NCs, such as Cu(2)ZnSnSe(4), Cu(InGa)Se(2), and CdSe. In the case of Cu(2)ZnSnSe(4), for example, the as-synthesized NCs possessed small size, high size monodispersity, strong absorbance in the visible region, and in particular a promising increase in photocurrent under AM1.5 illumination. The current preparation of the Se precursor is simple and convenient, which will promote the synthesis and practical applications of selenide NCs.

  1. Neutralization by Metal Ions of the Toxicity of Sodium Selenide

    PubMed Central

    Dauplais, Marc; Lazard, Myriam; Blanquet, Sylvain; Plateau, Pierre

    2013-01-01

    Inert metal-selenide colloids are found in animals. They are believed to afford cross-protection against the toxicities of both metals and selenocompounds. Here, the toxicities of metal salt and sodium selenide mixtures were systematically studied using the death rate of Saccharomyces cerevisiae cells as an indicator. In parallel, the abilities of these mixtures to produce colloids were assessed. Studied metal cations could be classified in three groups: (i) metal ions that protect cells against selenium toxicity and form insoluble colloids with selenide (Ag+, Cd2+, Cu2+, Hg2+, Pb2+ and Zn2+), (ii) metal ions which protect cells by producing insoluble metal-selenide complexes and by catalyzing hydrogen selenide oxidation in the presence of dioxygen (Co2+ and Ni2+) and, finally, (iii) metal ions which do not afford protection and do not interact (Ca2+, Mg2+, Mn2+) or weakly interact (Fe2+) with selenide under the assayed conditions. When occurring, the insoluble complexes formed from divalent metal ions and selenide contained equimolar amounts of metal and selenium atoms. With the monovalent silver ion, the complex contained two silver atoms per selenium atom. Next, because selenides are compounds prone to oxidation, the stabilities of the above colloids were evaluated under oxidizing conditions. 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB), the reduction of which can be optically followed, was used to promote selenide oxidation. Complexes with cadmium, copper, lead, mercury or silver resisted dissolution by DTNB treatment over several hours. With nickel and cobalt, partial oxidation by DTNB occurred. On the other hand, when starting from ZnSe or FeSe complexes, full decompositions were obtained within a few tens of minutes. The above properties possibly explain why ZnSe and FeSe nanoparticles were not detected in animals exposed to selenocompounds. PMID:23342137

  2. Magnetometer uses bismuth-selenide

    NASA Technical Reports Server (NTRS)

    Woollman, J. A.; Spain, I. L.; Beale, H.

    1972-01-01

    Characteristics of bismuth-selenide magnetometer are described. Advantages of bismuth-selenide magnetometer over standard magnetometers are stressed. Thermal stability of bismuth-selenide magnetometer is analyzed. Linearity of output versus magnetic field over wide range of temperatures is reported.

  3. Preparation and structure of the light rare-earth copper selenides LnCuSe 2 ( Ln=La, Ce, Pr, Nd, Sm)

    NASA Astrophysics Data System (ADS)

    Ijjaali, Ismail; Mitchell, Kwasi; Ibers, James A.

    2004-03-01

    The ternary selenides LnCuSe 2 ( Ln=La, Ce, Pr, Nd, Sm) have been synthesized by the reaction at 1173 K of Ln, Cu, and Se in a KBr or KI flux. The compounds, which are isostructural with LaCuS 2, crystallize with four formula units in the space group P2 1/ c of the monoclinic system. The structure may be thought of as consisting of layers of CuSe 4 tetrahedra separated by double layers of LnSe 7 monocapped trigonal prisms along the a-axis. Cell constants (Å or deg) at 153 K are: LaCuSe 2, 6.8142(5), 7.5817(6), 7.2052(6), 97.573(1)°; CeCuSe 2, 6.7630(5), 7.5311(6), 7.1650(6), 97.392(1)°; PrCuSe 2, 6.740(1), 7.481(1), 7.141(1), 97.374(2)°; NdCuSe 2, 6.7149(6), 7.4452(7), 7.1192(6), 97.310(1)°; SmCuSe 2, 6.6655(6), 7.3825(7), 7.0724(6), 97.115(1)°. There are no Se-Se bonds in the structure of LnCuSe 2; the formal oxidation states of Ln/Cu/Se are 3+/1+/2-.

  4. Improving the efficiency of copper indium gallium (Di-)selenide (CIGS) solar cells through integration of a moth-eye textured resist with a refractive index similar to aluminum doped zinc oxide

    SciTech Connect

    Burghoorn, M.; Kniknie, B.; Deelen, J. van; Ee, R. van; Xu, M.; Vroon, Z.; Belt, R. van de; Buskens, P. E-mail: buskens@dwi.rwth-aachen.de

    2014-12-15

    Textured transparent conductors are widely used in thin-film silicon solar cells. They lower the reflectivity at interfaces between different layers in the cell and/or cause an increase in the path length of photons in the Si absorber layer, which both result in an increase in the number of absorbed photons and, consequently, an increase in short-circuit current density (J{sub sc}) and cell efficiency. Through optical simulations, we recently obtained strong indications that texturing of the transparent conductor in copper indium gallium (di-)selenide (CIGS) solar cells is also optically advantageous. Here, we experimentally demonstrate that the J{sub sc} and efficiency of CIGS solar cells with an absorber layer thickness (d{sub CIGS}) of 0.85 μm, 1.00 μm and 2.00 μm increase through application of a moth-eye textured resist with a refractive index that is sufficiently similar to AZO (n{sub resist} = 1.792 vs. n{sub AZO} = 1.913 at 633 nm) to avoid large optical losses at the resist-AZO interface. On average, J{sub sc} increases by 7.2%, which matches the average reduction in reflection of 7.0%. The average relative increase in efficiency is slightly lower (6.0%). No trend towards a larger relative increase in J{sub sc} with decreasing d{sub CIGS} was observed. Ergo, the increase in J{sub sc} can be fully explained by the reduction in reflection, and we did not observe any increase in J{sub sc} based on an increased photon path length.

  5. Crystal structures of the four new quaternary copper(I)-selenides A0.5CuZrSe3 and ACuYSe3(A=Sr, Ba)

    NASA Astrophysics Data System (ADS)

    Maier, Stefan; Prakash, Jai; Berthebaud, David; Perez, Olivier; Bobev, Svilen; Gascoin, Franck

    2016-10-01

    The four new quaternary copper(I)-selenides, Sr0.5CuZrSe3 (a=3.8386(7), b=14.197(2), c=10.1577(17) Å), Ba0.5CuZrSe3 (a=3.8386(7), b=14.196(2), c=10.1577(17) Å), SrCuYSe3 (a=10.620(2), b=4.1000(8), c=13.540(3) Å) and BaCuYSe3 (a=4.1800(7), b=13.940(2), c=10.6200(17) Å) were synthesized by high-temperature solid state reactions and their crystal structures were determined using single-crystal X-ray diffraction. A0.5CuZrSe3 (A= Sr, Ba) and BaCuYSe3 crystallize in the KCuZrS3 structure type (Cmcm), while SrCuYSe3 is isostructural to Eu2CuS3 (Pnma). All compounds form layered structures in which the charge of the - ∞ 2[CuZrSe3 and 2 - ∞ 2[CuYSe3 ] layers as well as the site occupancy of the A cations depend on the transition metal. Combining the alkaline earth metals Sr and Ba with tetravalent Zr leads to the formation of cation vacancies between the - ∞ 2[CuZrSe3 ] layers and structure type as well as symmetry are determined by the ratio between the cation and transition metal ionic radii r(A2+)/r(M3+/4+).

  6. Improving the efficiency of copper indium gallium (Di-)selenide (CIGS) solar cells through integration of a moth-eye textured resist with a refractive index similar to aluminum doped zinc oxide

    NASA Astrophysics Data System (ADS)

    Burghoorn, M.; Kniknie, B.; van Deelen, J.; Xu, M.; Vroon, Z.; van Ee, R.; van de Belt, R.; Buskens, P.

    2014-12-01

    Textured transparent conductors are widely used in thin-film silicon solar cells. They lower the reflectivity at interfaces between different layers in the cell and/or cause an increase in the path length of photons in the Si absorber layer, which both result in an increase in the number of absorbed photons and, consequently, an increase in short-circuit current density (Jsc) and cell efficiency. Through optical simulations, we recently obtained strong indications that texturing of the transparent conductor in copper indium gallium (di-)selenide (CIGS) solar cells is also optically advantageous. Here, we experimentally demonstrate that the Jsc and efficiency of CIGS solar cells with an absorber layer thickness (dCIGS) of 0.85 μm, 1.00 μm and 2.00 μm increase through application of a moth-eye textured resist with a refractive index that is sufficiently similar to AZO (nresist = 1.792 vs. nAZO = 1.913 at 633 nm) to avoid large optical losses at the resist-AZO interface. On average, Jsc increases by 7.2%, which matches the average reduction in reflection of 7.0%. The average relative increase in efficiency is slightly lower (6.0%). No trend towards a larger relative increase in Jsc with decreasing dCIGS was observed. Ergo, the increase in Jsc can be fully explained by the reduction in reflection, and we did not observe any increase in Jsc based on an increased photon path length.

  7. Selenide retention by mackinawite.

    PubMed

    Finck, N; Dardenne, K; Bosbach, D; Geckeis, H

    2012-09-18

    The isotope (79)Se may be of great concern with regard to the safe disposal of nuclear wastes in deep geological repositories due to its long half-life and potential mobility in the geosphere. The Se mobility is controlled by the oxidation state: the oxidized species (Se(IV)) and (Se(VI)) are highly mobile, whereas the reduced species (Se(0) and Se(-II)) form low soluble solids. The mobility of this trace pollutant can be greatly reduced by interacting with the various barriers of the repository. Numerous studies report on the oxidized species retention by mineral phases, but only very scarce studies report on the selenide (Se(-II)) retention. In the present study, the selenide retention by coprecipitation with and by adsorption on mackinawite (FeS) was investigated. XRD and SEM analyses of the samples reveal no significant influence of Se on the mackinawite precipitate morphology and structure. Samples from coprecipitation and from adsorption are characterized at the molecular scale by a multi-edge X-ray absorption spectroscopy (XAS) investigation. In the coprecipitation experiment, all elements (S, Fe, and Se) are in a low ionic oxidation state and the EXAFS data strongly point to selenium located in a mackinawite-like sulfide environment. By contacting selenide ions with FeS in suspension, part of Se is located in an environment similar to that found in the coprecipitation experiment. The explanation is a dynamical dissolution-recrystallization mechanism of the highly reactive mackinawite. This is the first experimental study to report on selenide incorporation in iron monosulfide by a multi-edge XAS approach.

  8. Development of the data base for a degradation model of a selenide RTG. [Radioisotope Thermoelectric Generator

    NASA Technical Reports Server (NTRS)

    Stapfer, G.; Truscello, V. C.

    1977-01-01

    The paper is concerned with the evaluation of the materials used in a selenide radioisotope thermoelectric generator (RTG). These materials are composed of n-type gadolinium selenide and n-type copper selenide. A three-fold evaluation approach is being used: (1) the study of the rate of change of the thermal conductivity of the material, (2) the investigation of the long-term stability of the material's Seebeck voltage and electrical resistivity under current and temperature gradient conditions, and (3) determination of the physical behavior and compatibility of the material with surrounding insulation at elevated temperatures. Programmatically, the third category of characteristic evaluation is being emphasized.

  9. Neutralization by metal ions of the toxicity of sodium selenide.

    PubMed

    Dauplais, Marc; Lazard, Myriam; Blanquet, Sylvain; Plateau, Pierre

    2013-01-01

    Inert metal-selenide colloids are found in animals. They are believed to afford cross-protection against the toxicities of both metals and selenocompounds. Here, the toxicities of metal salt and sodium selenide mixtures were systematically studied using the death rate of Saccharomyces cerevisiae cells as an indicator. In parallel, the abilities of these mixtures to produce colloids were assessed. Studied metal cations could be classified in three groups: (i) metal ions that protect cells against selenium toxicity and form insoluble colloids with selenide (Ag⁺, Cd²⁺, Cu²⁺, Hg²⁺, Pb²⁺ and Zn²⁺), (ii) metal ions which protect cells by producing insoluble metal-selenide complexes and by catalyzing hydrogen selenide oxidation in the presence of dioxygen (Co²⁺ and Ni²⁺) and, finally, (iii) metal ions which do not afford protection and do not interact (Ca²⁺, Mg²⁺, Mn²⁺) or weakly interact (Fe²⁺) with selenide under the assayed conditions. When occurring, the insoluble complexes formed from divalent metal ions and selenide contained equimolar amounts of metal and selenium atoms. With the monovalent silver ion, the complex contained two silver atoms per selenium atom. Next, because selenides are compounds prone to oxidation, the stabilities of the above colloids were evaluated under oxidizing conditions. 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB), the reduction of which can be optically followed, was used to promote selenide oxidation. Complexes with cadmium, copper, lead, mercury or silver resisted dissolution by DTNB treatment over several hours. With nickel and cobalt, partial oxidation by DTNB occurred. On the other hand, when starting from ZnSe or FeSe complexes, full decompositions were obtained within a few tens of minutes. The above properties possibly explain why ZnSe and FeSe nanoparticles were not detected in animals exposed to selenocompounds.

  10. COPPER(1-Y)SILVER(Y)INDIUM - DISULFIDE(1-X)SELENIDE(2X) as a Prototype of the Pentenary Chalcopyrite Semiconductor Systems.

    NASA Astrophysics Data System (ADS)

    Chapman, Glenn Harrison

    The group III-V mixed alloy quarternary semiconductors, such as Ga(,(1-y))In(,y)As(,(1-x))P(,x) have been extensively employed in lattice matching different semiconducting layers (at specific bandgaps) to form heterojunction electro-optical devices. However, these cover only a limited set of direct bandgap/lattice constant combinations. The analogous pentenary alloys, consisting of the ternary chalcopyrite groups I -III-VI(,2) and II-IV-V(,2), have the potential of similar applications as they cover an even wider band/lattice range. As a prototype of such alloys, samples of the pentenary Cu(,(1 -y))Ag(,y)InS(,2(1-x))Se(,2x) have been synthesized and studied. Samples were prepared by reacting stoichimetric powder mixtures at about 900 C. X-ray diffractometry tests suggest the compounds maintained complete powder solid solubility throughout the system in the chalcopyrite crystal structure. The intrinsic conductivity type of the alloys appear to follow a trend towards n-type for silver and sulfur rich compounds, while forming p-type for copper and selenium rich materials. The bandgap of these samples were measured using cathodoluminescence techniques, which generally have some ambiguity in their resulting estimates. To generate better values of the band parameters extensive computer modeling for the emission spectra from heavily doped direct bandgap materials was done. The effect of band tails and Gaussian impurity states on the luminescence spectra was studied for changes in doping densities, temperature and carrier injection levels. Formulae were derived from these models to obtain better estimates of the bandgap and impurity activation levels. Algorithms were developed to obtain the impurity spreading energy of a tailed or Gaussian band, and the quasi-Fermi energy levels for injected current in a material with a specific band structure. Cathodoluminescence measurements were made at 300 and 77 K on the samples. As predicted by the models, it was found easier to

  11. Nonstoichiometry of crystalline cadmium selenide

    SciTech Connect

    Kharif, Ya.L.; Brezhnev, V.Yu.; Kovtunenko, P.V.

    1987-08-01

    A highly sensitive physicochemical method is developed for determining the cadmium concentration (10/sup -5/ at. % for a 10 g sample weight), dissolved in cadmium selenide. The nonstoichiometry of cadmium selenide crystals is studied after high-temperature annealing at 870-1370/sup 0/K in cadmium vapor. For the first time, it is discovered that in the investigated crystals the dissolved cadmium exists primarily in the form of electrically neutral defects, which are presumably clusters of selenium vacancies with low mobility.

  12. Advanced selenide thermoelectric development program. Final report

    SciTech Connect

    Seetoo, W.R.

    1981-07-20

    The primary objective of this work was to demonstrate that copper silver selenide and TAGS could be segmented. The hot junction temperature was planned to be 725/sup 0/C with the segmentation temperature at 400/sup 0/C, both temperatures were selected to prevent excessive sublimation from the hot ends of the segments, respectively. The program was planned as a cooperative effort between General Atomic company and Teledyne Energy Systems. Accordingly, General Atomic synthesized the CuAgSe that was used to fabricate the test hardware that was ultimately delivered to General Atomic for testing. Both the CuAgSe and TAGS were hot pressed in an argon atmosphere then the segments were furnace-bonded to each other. A secondary objective was to produce CuAgSe powder by rapid solidification.

  13. Doping in Zinc Selenide

    NASA Astrophysics Data System (ADS)

    Wheeler, Edward Dean

    An experimental technique ensuring the incorporation of substitutional arsenic and copper doping in ZnSe is presented. Two techniques are investigated. In each, neutron transmutation doping is employed to introduce arsenic and copper dopants in ZnSe. In the first technique, as-grown crystals of ZnSe are exposed to thermal neutrons. The crystals are thermally annealed after irradiation in order to repair the neutron induced lattice damage. The thermal annealing schedules employed in this work, however, do not fully repair the ZnSe lattice. In the second technique, homoepitaxial layers of ZnSe are deposited with irradiated zinc and selenium as source materials. High quality layers of ZnSe, characterized by x-ray diffraction and low temperature photoluminescence, are produced. The long half lives of As^ {75} and Zn^{65} allow the epitaxial layers to be formed prior to nuclear decay. Since the nuclear recoil associated with the decays are not sufficient to displace the dopant nuclei from their substitutional lattice sites, the technique results in isolated As_{Se } or isolated Cu_{Zn } being introduced in layers of ZnSe after crystal growth. Since the dopants are introduced in the bulk crystal after crystal growth, the doping process is decoupled from any interactions present during crystal growth. A technique in which crystal doping is decoupled from crystal growth provides several unique probes for arsenic and copper doping in ZnSe.

  14. Low-Resistivity Zinc Selenide for Heterojunctions

    NASA Technical Reports Server (NTRS)

    Stirn, R. J.

    1986-01-01

    Magnetron reactive sputtering enables doping of this semiconductor. Proposed method of reactive sputtering combined with doping shows potential for yielding low-resistivity zinc selenide films. Zinc selenide attractive material for forming heterojunctions with other semiconductor compounds as zinc phosphide, cadmium telluride, and gallium arsenide. Semiconductor junctions promising for future optoelectronic devices, including solar cells and electroluminescent displays. Resistivities of zinc selenide layers deposited by evaporation or chemical vapor deposition too high to form practical heterojunctions.

  15. Dislocation Etching Solutions for Mercury Cadmium Selenide

    DTIC Science & Technology

    2014-09-01

    Dislocation Etching Solutions for Mercury Cadmium Selenide by Kevin Doyle and Sudhir Trivedi ARL-CR-0744 September 2014...Etching Solutions for Mercury Cadmium Selenide Kevin Doyle and Sudhir Trivedi Sensors and Electron Devices Directorate, ARL prepared by...Solutions for Mercury Cadmium Selenide 5a. CONTRACT NUMBER W811NF-12-2-0019 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Kevin Doyle and

  16. Mercury Cadmium Selenide for Infrared Detection

    DTIC Science & Technology

    2013-06-01

    REPORT Mercury cadmium selenide for infrared detection 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Samples of HgCdSe alloys were grown via molecular...NUMBER John Dinan 512-245-6711 3. DATES COVERED (From - To) Standard Form 298 (Rev 8/98) Prescribed by ANSI Std. Z39.18 - Mercury cadmium selenide for...PAGE (SF298) (Continuation Sheet) Continuation for Block 13 ARO Report Number Mercury cadmium selenide for infrared detection Block 13

  17. Biological Chemistry of Hydrogen Selenide.

    PubMed

    Cupp-Sutton, Kellye A; Ashby, Michael T

    2016-11-22

    There are no two main-group elements that exhibit more similar physical and chemical properties than sulfur and selenium. Nonetheless, Nature has deemed both essential for life and has found a way to exploit the subtle unique properties of selenium to include it in biochemistry despite its congener sulfur being 10,000 times more abundant. Selenium is more easily oxidized and it is kinetically more labile, so all selenium compounds could be considered to be "Reactive Selenium Compounds" relative to their sulfur analogues. What is furthermore remarkable is that one of the most reactive forms of selenium, hydrogen selenide (HSe(-) at physiologic pH), is proposed to be the starting point for the biosynthesis of selenium-containing molecules. This review contrasts the chemical properties of sulfur and selenium and critically assesses the role of hydrogen selenide in biological chemistry.

  18. Biological Chemistry of Hydrogen Selenide

    PubMed Central

    Cupp-Sutton, Kellye A.; Ashby, Michael T.

    2016-01-01

    There are no two main-group elements that exhibit more similar physical and chemical properties than sulfur and selenium. Nonetheless, Nature has deemed both essential for life and has found a way to exploit the subtle unique properties of selenium to include it in biochemistry despite its congener sulfur being 10,000 times more abundant. Selenium is more easily oxidized and it is kinetically more labile, so all selenium compounds could be considered to be “Reactive Selenium Compounds” relative to their sulfur analogues. What is furthermore remarkable is that one of the most reactive forms of selenium, hydrogen selenide (HSe− at physiologic pH), is proposed to be the starting point for the biosynthesis of selenium-containing molecules. This review contrasts the chemical properties of sulfur and selenium and critically assesses the role of hydrogen selenide in biological chemistry. PMID:27879667

  19. Copper

    Integrated Risk Information System (IRIS)

    Copper ; CASRN 7440 - 50 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects )

  20. Crystallographic Description for Nanoparticle Asemblies - Application to Cadmium Selenide Clusters

    DTIC Science & Technology

    2001-01-01

    Application to Cadmium Selenide Clusters DISTRIBUTION: Approved for public release, distribution unlimited This paper is part of the following report...Proc. Vol. 635 © 2001 Materials Research Society Crystallographic Description for Nanoparticle Asemblies - Application to Cadmium Selenide Clusters. A

  1. Silica glasses with nanoparticles of copper compounds: spectroscopy properties and laser passive shutter application

    NASA Astrophysics Data System (ADS)

    Yumashev, Konstantin V.; Prokoshin, Pavel V.; Zolotovskaya, Svetlana A.; Gurin, Valerij S.; Alexeenko, Alexander A.

    2003-11-01

    Sol-gel glasses containing copper selenide nanoparticles and having absorption band at 1.1?2.2 ?m can be used as saturable absorber passive shutter for Q-switching and mode-locking of the solid-state lasers operating in the wavelength range of 1.0?1.5 ?m. The bleaching relaxation time of the glasses was measured to be 0.46?1.4 ns in dependence on copper selenide stoichiometry.

  2. Selenide technology evaluation program at JPL

    NASA Technical Reports Server (NTRS)

    Stapfer, G.; Garvey, L.

    1978-01-01

    Results are presented for experimental and analytical investigations of the overall performance of a selenide radioisotope thermoelectric generator intended to provide the electrical power for interplanetary spaceprobes such as the Galileo mission to Jupiter. The discussion focuses on technology areas of concern, electrical properties of the selenide thermoelectric materials used, and thermal conductivity of these materials for superior performance. It is shown that the selenide thermoelectric materials offer the advantage of high conversion efficiency. The long-life requirement on the power system for the Galileo mission necessitates proper design, known fabrication techniques, and reproducible assembly techniques in order to ensure stability of the thermoelectric properties. However, the thermophysical properties - sublimation and creep - of the p-material remains an area of considerable concern.

  3. Copper(I) electrode function of two types of copper(II) ion-selective electrodes.

    PubMed

    Neshkova, M; Sheytanov, H

    1985-08-01

    The response of two types of solid-state copper ion-selective electrodes with homogeneous membranes of CuAgSe and Cu(2-x)Se has been investigated in copper(I) solutions, prepared electrochemically by insitu generation from a copper anode in chloride medium. The selectivity coefficient K(pot)(Cu+, Cu(2+)) both types of electrodes has been determined. It is 10(-5.7) for the copper selenide sensor, and 10(-6.2) for the copper silver selenide one. These values are very close to that calculated for an exchange reaction proceeding on the electrode surface. The similarity in K(pot)(Cu+ ,Cu(2+)) values for different chalcogenidebased sensors suggests a common potential-generating mechanism. High chloride concentration does not interfere with the electrode response towards Cu(I), but distorts the electrode response to Cu(II).

  4. Alloyed copper chalcogenide nanoplatelets via partial cation exchange reactions.

    PubMed

    Lesnyak, Vladimir; George, Chandramohan; Genovese, Alessandro; Prato, Mirko; Casu, Alberto; Ayyappan, S; Scarpellini, Alice; Manna, Liberato

    2014-08-26

    We report the synthesis of alloyed quaternary and quinary nanocrystals based on copper chalcogenides, namely, copper zinc selenide-sulfide (CZSeS), copper tin selenide-sulfide (CTSeS), and copper zinc tin selenide-sulfide (CZTSeS) nanoplatelets (NPLs) (∼20 nm wide) with tunable chemical composition. Our synthesis scheme consisted of two facile steps: i.e., the preparation of copper selenide-sulfide (Cu2-xSeyS1-y) platelet shaped nanocrystals via the colloidal route, followed by an in situ cation exchange reaction. During the latter step, the cation exchange proceeded through a partial replacement of copper ions by zinc or/and tin cations, yielding homogeneously alloyed nanocrystals with platelet shape. Overall, the chemical composition of the alloyed nanocrystals can easily be controlled by the amount of precursors that contain cations of interest (e.g., Zn, Sn) to be incorporated/alloyed. We have also optimized the reaction conditions that allow a complete preservation of the size, morphology, and crystal structure as that of the starting Cu2-xSeyS1-y NPLs. The alloyed NPLs were characterized by optical spectroscopy (UV-vis-NIR) and cyclic voltammetry (CV), which demonstrated tunability of their light absorption characteristics as well as their electrochemical band gaps.

  5. Polarization Effects in the Luminescence of Cadmium Selenide Electrodes.

    DTIC Science & Technology

    1983-09-29

    UWIS/DC/TR-83/3 Polarization Effects in the Luminescence of Cadmium Selenide Electrodes by Holger H. Streckert, Hal Van Ryswyk, Richard N. Biagioni...the Luminescence of Cadmium Selenide Electrodes______________ S. PERFORMING ORG. REPORT NUMBER 7. AUT,4OR(e) S. CONTRACT OR GRANT NUMBER~q) Holger H...Continue an reverse aide if necieemy arid Identify, by block number) Cadmium selenide electrodes, photoluminescence, electroluminescence, polarized

  6. Simple preparation of a cadmium selenide-montmorillonite hybrid.

    PubMed

    Ontam, Areeporn; Khaorapapong, Nithima; Ogawa, Makoto

    2011-05-15

    The immobilization of organically modified cadmium selenide on montmorillonite was investigated by the reaction of modified cadmium selenide nanoparticles with montmorillonite. The intercalation of the nanoparticles was indicated by the expansion of the interlayer space and spectroscopic observations. The diffuse reflectance absorption spectrum of the product showed absorption onset at 567 nm. In comparison to the bulk cadmium selenide, the blue shift of the absorption onset of the hybrid was ascribed to the quantum size effect of the modified cadmium selenide nanoparticles. This study provides a new method for introducing nanoparticles into the interlayer space of layered inorganic materials.

  7. The heat capacity of solid antimony selenide

    NASA Astrophysics Data System (ADS)

    Pashinkin, A. S.; Malkova, A. S.; Mikhailova, M. S.

    2008-06-01

    The literature data on the heat capacity of solid antimony selenide over the temperature range 53 K- T m were analyzed. The heat capacity of Sb2Se3 was measured from 350 to 600 K on a DSM-2M calorimeter. The experimental data were used to calculate the dependence C p = a + bT + cT -2 and the thermodynamic functions of solid Sb2Se3 over the temperature range 298.15 700 K.

  8. [Di­aqua­sesqui(nitrato-κO)hemi(perchlorato-κO)copper(II)]-μ-{bis­[5-methyl-3-(pyridin-2-yl)-1H-pyrazol-4-yl] selenide}-[tri­aqua­(perchlorato-κO)copper(II)] nitrate monohydrate

    PubMed Central

    Seredyuk, Maksym; Pavlenko, Vadim A.; Znovjyak, Kateryna O.; Gumienna-Kontecka, Elzbieta; Iskenderov, Turganbay S.

    2013-01-01

    In the binuclear title complex, [Cu2(ClO4)1.5(NO3)1.5(C18H16N6Se)(H2O)5]NO3·H2O, both CuII ions are hexa­coordinated by O and N atoms, thus forming axially elongated CuO4N2 octa­hedra. The equatorial plane of each octa­hedron is formed by one chelating pyrazole–pyridine fragment of the organic ligand and two water mol­ecules. The axial positions in one octa­hedron are occupied by a water mol­ecule and a monodentately coordinated perchlorate anion, while those in the other are occupied by a nitrate anion and a disordered perchlorate/nitrate anion with equal site occupancy. The pyrazole–pyridine units of the organic selenide are trans-oriented to each other with a C—Se—C angle of 96.01 (14)°. In the crystal, uncoordinated nitrate anions and the coordinating water mol­ecules are involved in O—H⋯O and N—H⋯O hydrogen bonds, forming a bridge between the pyrazole group and the coordinating water mol­ecules. Further O—H⋯O hydrogen bonds between the complex mol­ecules and a π–π stacking inter­action with a centroid–centroid distance of 3.834 (4) Å are also observed. PMID:23794981

  9. Synthesis and characterization of luminescent cadmium selenide/zinc selenide/zinc sulfide cholinomimetic quantum dots.

    PubMed

    Gégout, Claire; McAtee, Maria L; Bennett, Nichole M; Viranga Tillekeratne, L M; Kirchhoff, Jon R

    2012-08-07

    Luminescent quantum dots conjugated with highly selective molecular recognition ligands are widely used for targeting and imaging biological structures. In this paper, water soluble cholinomimetic cadmium selenide (core), zinc selenide/zinc sulfide (shell) quantum dots were synthesized for targeting cholinergic sites. Cholinomimetic specificity was incorporated by conjugation of the quantum dots to an aminated analogue of hemicholinium-15, a well known competitive inhibitor of the high affinity choline uptake transporter. Detailed evaluation of the nanocrystal synthesis and characterization of the final product was conducted by (1)H and (31)P NMR, absorption and emission spectroscopy, as well as transmission electron microscopy.

  10. Photo-induced transmittance in copper selenide nanowires

    NASA Astrophysics Data System (ADS)

    Statkutė, G.; Mikulskas, I.; Jagminas, A.; Tomašiūnas, R.

    2008-01-01

    Photo-induced transmission was investigated in Cu 1.7Se nanowires electrochemically deposited in alumina matrix pores with a central channel of the diameters of 12, 15 and 60 nm by means of the degenerate picosecond pump-probe technique at 1.064 μm wavelength. Resonant excitation intensity dependencies were interpreted. Absorption saturation was ascertained as a result of the drain of acceptor shallow centers. The estimated absorption cross-section was 10 -12 cm 2, saturation intensity - was 1-10 mJ cm -2.

  11. Interferences in electrochemical hydride generation of hydrogen selenide

    NASA Astrophysics Data System (ADS)

    Bolea, E.; Laborda, F.; Belarra, M. A.; Castillo, J. R.

    2001-12-01

    Interferences from Cu(II), Zn(II), Pt(IV), As(III) and nitrate on electrochemical hydride generation of hydrogen selenide were studied using a tubular flow-through generator, flow injection sample introduction and quartz tube atomic absorption spectrometry. Comparison with conventional chemical generation using tetrahydroborate was also performed. Lead and reticulated vitreous carbon (RVC), both in particulate form, were used as cathode materials. Signal supressions up to 60-75%, depending on the cathode material, were obtained in the presence of up to 200 mg l-1 of nitrate due to the competitive reduction of the anion. Interference from As(III) was similar in electrochemical and chemical generation, being related to the quartz tube atomization process. Zinc did not interfere up to Se/Zn ratios 1:100, whereas copper and platinum showed suppression levels up to 50% for Se/interferent ratios 1:100. Total signal suppression was observed in presence of Se/Cu ratios 1:100 when RVC cathodes were used. No memory effects were observed in any case. Scanning electron microscopy and squared wave voltametry studies supported the interference mechanism based on the decomposition of the hydride on the dispersed particles of the reduced metal.

  12. Electronic and magnetic properties of orthorhombic iron selenide

    NASA Astrophysics Data System (ADS)

    Lovesey, S. W.

    2016-02-01

    Iron orbitals in orthorhombic iron selenide (FeSe) can produce chargelike multipoles that are polar (parity-odd). Orbitals in question include Fe (3 d ), Fe (4 p ), and p -type ligands that participate in transport properties and bonding. The polar multipoles may contribute weak, space-group forbidden Bragg spots to diffraction patterns collected with x rays tuned in energy to a Fe atomic resonance (Templeton & Templeton scattering). Ordering of conventional, axial magnetic dipoles does not accompany the tetragonal-orthorhombic structural phase transition in FeSe, unlike other known iron-based superconductors. We initiate a new line of inquiry for this puzzling property of orthorhombic FeSe, using a hidden magnetic order that belongs to the m'm'm' magnetic crystal class. It is epitomized by the absence of ferromagnetism and axial magnetic dipoles and the appearance of magnetic monopoles and magnetoelectric quadrupoles. A similar magnetic order occurs in cuprate superconductors, yttrium barium copper oxide and Hg1201, where it was unveiled with the Kerr effect and in Bragg diffraction patterns revealed by polarized neutrons.

  13. Electrothermal atomic absorption determination of silver in cadmium selenide

    SciTech Connect

    Khozhainov, Y.M.; Deinikina, N.P.; Tyurin, O.A.

    1985-10-01

    The authors developed an atomic absorption method for determining trace silver in cadmium selenide, restricted to samples of 3 - 10 mg. Used as cp reagents, including those further purified, were distilled nitric acid, isothermally distilled hydrochloric acid, cadmium selenide, and S /SUB r/ grade silver with a purity of 99.999%.

  14. Analytical predictions of selenide RTG power degradation

    NASA Technical Reports Server (NTRS)

    Noon, E. L.; Stapfer, G.; Raag, V.

    1978-01-01

    A mathematical model for the performance and degradation analysis of an RTG using the newly developed selenide thermoelectric materials has been developed at JPL. The computerized model is quite comprehensive and enables the accurate detailing of the electrical and thermal effects that take place within the thermocouple under any desired set of operation conditions, including heat input, ambient temperature and load conditions. The paper discusses the logic flow of the computer model and presents the time and temperature dependent results for various degradation mechanisms and rates as they have been established to date.

  15. Determination of the nonstoichiometry of cadmium selenide

    SciTech Connect

    Brezhnev, V.Yu.; Kharif, Ya.L.; Kovtunenko, P.V.

    1986-11-01

    In the annealing of cadmium selenide crystals, cadmium dissolves in the crystals. As a result, their composition deviates from stoichiometry, which affects their electrical conductivity and photosensitivity. In order to obtain crystals with the required properties, it is necessary to determine the amount of dissolved cadmium, i.e., the nonstoichiometry of the crystals. In this paper, the authors experimented with and report on the two methods of extracting dissolved cadmium: recrystallization of the sample by evaporation and condensation; and by creating the conditions for the occurrence of a diffusion stream of cadmium from the bulk to the surface of the crystals.

  16. Lattice vibrational properties of americium selenide

    NASA Astrophysics Data System (ADS)

    Arya, B. S.; Aynyas, Mahendra; Sanyal, S. P.

    2016-05-01

    Lattice vibrational properties of AmSe have been studied by using breathing shell models (BSM) which includes breathing motion of electrons of the Am atoms due to f-d hybridization. The phonon dispersion curves, specific heat calculated from present model. The calculated phonon dispersion curves of AmSe are presented follow the same trend as observed in uranium selenide. We discuss the significance of this approach in predicting the phonon dispersion curves of these compounds and examine the role of electron-phonon interaction.

  17. [Optical constants determination of zinc selenide by inversing transmittance spectrogram].

    PubMed

    Li, Dong; Ai, Qing; Xia, Xin-Lin

    2013-04-01

    The transmittance models of single slab and two spliced slabs were built, and a new method to determine optical constants of materials was proposed based on inversing the transmittance spectrograms of single slab and two spliced slabs. The measurements of transmittance spectrogram of zinc selenide glass slabs with different thickness in the infrared wavelength range of 1.33-21 microm at normal incidence were investigated by Bruke V70 FTIR spectrometer. The optical constants of zinc selenide were achieved by the inverse methods. The results indicate that the optical constants of zinc selenide determined by the new inverse method are in good agreement with previous data sets.

  18. Handbook of Phase Transition Sulfides, Selenides and Tellurides,

    DTIC Science & Technology

    1984-07-01

    fCAa24 o c()0 an E -b.Sldln () ahdln - 2 M ; do-a.5ie .I OII A-32. CdSe Cadnim Monoselenlde Cadmium selenide is a metal-nonmetal phase transition...RD-R146 658 HANDBOOK OF PHASE TRANSITION SULFIDES SELENIDES AND 1/3 rELLURIDES(U) TACTICAL WEAPONS GUIDANCE AND CONTROL INFORMATION ANALYSIS CE. W J...CIAL- WE:a\\FONf* C7UIDAt-NCE: & =ONrR DL. INP1:XRMATK3N At-LASIS C:EN*T7R HANDBOOK OF PHASE TRANSITION SULFIDES, SELENIDES AND TELLURIDES WALTER J

  19. Infrared birefringence spectra for cadmium sulfide and cadmium selenide.

    PubMed

    Chenault, D B; Chipman, R A

    1993-08-01

    Measurements of the birefringence spectra for cadmium sulfide and cadmium selenide from 2.5 to 16.5µm obtained with a rotating sample spectropolarimeter are presented. Because of the similarity in the birefringence spectra for cadmium sulfide and cadmium selenide, a highly achromatic IR retarder can be constructed from a combination of these materials. The ordinary and extraordinary refractive indices for cadmium sulfide are estimated in the region from 10.6 to 15 µm and for cadmium selenide from 10.6 to 16.5 µm by combining these birefringence data with an extrapolation of previous dispersion relations.

  20. Characterization of cadmium selenide electrodeposited from diethylene glycol solution containing tri-n-butylphosphine selenide

    SciTech Connect

    Sanders, B.W.; Cocivera, M.

    1987-05-01

    Thin film cadmium selenide has been prepared by a new electrochemical process in which the film is deposited at the cathode from a nonaqueous solution containing tri-n-butylphosphine selenide as the selenium source. The films are found to be less dense than those prepared using selenosulfite ion. The as-deposited films appear free of cracks and pinholes when deposited on titanium, but cracks develop when the films are annealed. A stoichiometric composition is obtained for the film over a 0.4V potential range. Power conversion efficiencies for films prepared under a variety of conditions range from 1.0 to 4.2% for surface areas ca. 1.0 cm/sup 2/. The presence of large concentrations of chloride ion in the deposition solution seems to have little effect on the composition or photoresponse of the film. Diethylene glycol appears to be a better solvent than propylene carbonate for this deposition process.

  1. Cuprous selenide and sulfide form improved photovoltaic barriers

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Photovoltaic barriers formed by depositing a layer of polycrystalline cuprous sulfide or cuprous selenide on gallium arsenide are chemically and electrically stable. The stability of these barrier materials is significantly greater than that of cuprous iodide.

  2. Synthesis and high temperature transport properties of new quaternary layered selenide NaCuMnSe{sub 2}

    SciTech Connect

    Pavan Kumar, V.; Varadaraju, U.V.

    2014-04-01

    Synthesis and high temperature transport properties of NaCu{sub 1+x}Mn{sub 1−x}Se{sub 2}, (x=0−0.75) a new quaternary layered selenide, are reported. NaCuMnSe{sub 2} crystallizes in a trigonal unit cell with space group of P-3m1 (a=4.1276 Å, c=7.1253 Å). The isovalent substitution of Mn{sup 2+} by Cu{sup 2+} is carried out. All the compositions show semiconducting nature, whereas the Seebeck coefficient increases gradually over the entire measured temperature range. Compositions with x=0 and 0.025 follow thermally activated behavior. With increase in copper concentration the conduction mechanism transforms to 2D variable range hopping (VRH) for x=0.05 and 0.075. - Graphical abstract: Crystal structure of NaCuMnSe{sub 2}. - Highlights: • A new quaternary layered selenide NaCuMnSe{sub 2} is synthesized. • All the compositions show semiconducting nature, whereas the Seebeck coefficient increases gradually over the entire measured temperature range. • Conduction mechanism transforms from thermally activated behavior to 2D variable range hopping with increase in copper concentration.

  3. Precursor conversion kinetics and the nucleation of cadmium selenide nanocrystals.

    PubMed

    Owen, Jonathan S; Chan, Emory M; Liu, Haitao; Alivisatos, A Paul

    2010-12-29

    The kinetics of cadmium selenide (CdSe) nanocrystal formation was studied using UV-visible absorption spectroscopy integrated with an automated, high-throughput synthesis platform. Reaction of anhydrous cadmium octadecylphosphonate (Cd-ODPA) with alkylphosphine selenides (1, tri-n-octylphosphine selenide; 2, di-n-butylphenylphosphine selenide; 3, n-butyldiphenylphosphine selenide) in recrystallized tri-n-octylphosphine oxide was monitored by following the absorbance of CdSe at λ = 350 nm, where the extinction coefficient is independent of size, and the disappearance of the selenium precursor using {(1)H}(31)P NMR spectroscopy. Our results indicate that precursor conversion limits the rate of nanocrystal nucleation and growth. The initial precursor conversion rate (Q(o)) depends linearly on [1] (Q(o)(1) = 3.0-36 μM/s) and decreases as the number of aryl groups bound to phosphorus increases (1 > 2 > 3). Changes to Q(o) influence the final number of nanocrystals and thus control particle size. Using similar methods, we show that changing [ODPA] has a negligible influence on precursor reactivity while increasing the growth rate of nuclei, thereby decreasing the final number of nanocrystals. These results are interpreted in light of a mechanism where the precursors react in an irreversible step that supplies the reaction medium with a solute form of the semiconductor.

  4. Ex Situ Formation of Metal Selenide Quantum Dots Using Bacterially Derived Selenide Precursors

    SciTech Connect

    Fellowes, Jonathan W.; Pattrick, Richard; Lloyd, Jon; Charnock, John M.; Coker, Victoria S.; Mosselmans, JFW; Weng, Tsu-Chien; Pearce, Carolyn I.

    2013-04-12

    Luminescent quantum dots were synthesized using bacterially derived selenide (SeII-) as the precursor. Biogenic SeII- was produced by the reduction of Se-IV by Veillonella atypica and compared directly against borohydride-reduced Se-IV for the production of glutathione-stabilized CdSe and beta-mercaptoethanol-stabilized ZnSe nanoparticles by aqueous synthesis. Biological SeII- formed smaller, narrower size distributed QDs under the same conditions. The growth kinetics of biologically sourced CdSe phases were slower. The proteins isolated from filter sterilized biogenic SeII- included a methylmalonyl-CoA decarboxylase previously characterized in the closely related Veillonella parvula. XAS analysis of the glutathione-capped CdSe at the S K-edge suggested that sulfur from the glutathione was structurally incorporated within the CdSe. A novel synchrotron based XAS technique was also developed to follow the nucleation of biological and inorganic selenide phases, and showed that biogenic SeII- is more stable and more resistant to beam-induced oxidative damage than its inorganic counterpart. The bacterial production of quantum dot precursors offers an alternative, 'green' synthesis technique that negates the requirement of expensive, toxic chemicals and suggests a possible link to the exploitation of selenium contaminated waste streams.

  5. Ex situ formation of metal selenide quantum dots using bacterially derived selenide precursors.

    PubMed

    Fellowes, J W; Pattrick, R A D; Lloyd, J R; Charnock, J M; Coker, V S; Mosselmans, J F W; Weng, T-C; Pearce, C I

    2013-04-12

    Luminescent quantum dots were synthesized using bacterially derived selenide (Se(II-)) as the precursor. Biogenic Se(II-) was produced by the reduction of Se(IV) by Veillonella atypica and compared directly against borohydride-reduced Se(IV) for the production of glutathione-stabilized CdSe and β-mercaptoethanol-stabilized ZnSe nanoparticles by aqueous synthesis. Biological Se(II-) formed smaller, narrower size distributed QDs under the same conditions. The growth kinetics of biologically sourced CdSe phases were slower. The proteins isolated from filter sterilized biogenic Se(II-) included a methylmalonyl-CoA decarboxylase previously characterized in the closely related Veillonella parvula. XAS analysis of the glutathione-capped CdSe at the S K-edge suggested that sulfur from the glutathione was structurally incorporated within the CdSe. A novel synchrotron based XAS technique was also developed to follow the nucleation of biological and inorganic selenide phases, and showed that biogenic Se(II-) is more stable and more resistant to beam-induced oxidative damage than its inorganic counterpart. The bacterial production of quantum dot precursors offers an alternative, 'green' synthesis technique that negates the requirement of expensive, toxic chemicals and suggests a possible link to the exploitation of selenium contaminated waste streams.

  6. Superconductivity in alkali metal intercalated iron selenides

    NASA Astrophysics Data System (ADS)

    Krzton-Maziopa, A.; Svitlyk, V.; Pomjakushina, E.; Puzniak, R.; Conder, K.

    2016-07-01

    Alkali metal intercalated iron selenide superconductors A x Fe2-y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations.

  7. Preparation and Characterization of Silver Selenide Thin Film

    NASA Astrophysics Data System (ADS)

    Chandrasekar, L. Bruno; Vijayalakshmi, R.; Rajeswari, B.; Chandramohan, R.; Arivazhagan, G.; Packiaseeli, S. Arulmozhi

    2014-12-01

    Silver selenide, a phase-changing chalcogenide material, is prepared using electro deposition method for various molarities. X-ray diffraction studies show the cubic lattice of the material. The micro-structural properties such as grain size, strain, dislocation density, and texture coefficient are examined. The lattice constant is calculated using Nelson-Relay function. Morphological studies are done and uniform distributions of grains are observed. High purities of thin films are confirmed by energy dispersive X-ray analysis. The band gap is calculated using UV-vis spectroscopy and photoluminescence technique, and hence, the Stokes's effect is observed in silver selenide thin films. It is the first time that the lattice constant and the Urbach energy for various molarities in the case of silver selenide thin films are reported.

  8. Ovonic type switching in tin selenide thin films

    NASA Technical Reports Server (NTRS)

    Baxter, C. R.; Mclennan, W. D.

    1975-01-01

    Amorphous tin selenide thin films which possess Ovonic type switching properties are fabricated using vacuum deposition techniques. The devices are fabricated in a planar configuration and consist of amorphous tin selenide deposited over silver contacts. Results obtained indicate that Ovonic type memory switching does occur in these films with the energy density required for switching from a high impedance to a low impedance state being dependent on the spacing between the electrodes of the device. There is also a strong implication that the switching is a function of the magnitude of the applied voltage pulse.

  9. Enhanced thermoelectric performance of spark plasma sintered copper-deficient nanostructured copper selenide

    NASA Astrophysics Data System (ADS)

    Tyagi, Kriti; Gahtori, Bhasker; Bathula, Sivaiah; Jayasimhadri, M.; Singh, Niraj Kumar; Sharma, Sakshi; Haranath, D.; Srivastava, A. K.; Dhar, Ajay

    2015-06-01

    We report the thermoelectric properties of nanostructured Cu-deficient Cu2Se, which was synthesized by high energy ball milling followed by spark plasma sintering. Our method obtained a significant enhancement in the thermoelectric figure of merit (ZT), i.e., ~1.4 at 973 K, which was ~30% higher than its bulk counterpart. This enhancement in the thermoelectric performance was due mainly to a significant reduction in the lattice thermal conductivity, which was attributed to enhanced phonon scattering at various length scales by nanoscale defects as well as abundant nanograin boundaries. The nanoscale defects were characterized by transmission electron microscopy of the nanostructured Cu2-xSe samples, which formed the basis of the ZT enhancement.

  10. Characterization of zinc selenide single crystals

    NASA Technical Reports Server (NTRS)

    Gerhardt, Rosario A.

    1996-01-01

    ZnSe single crystals of high quality and low impurity levels are desired for use as substrates in optoelectronic devices. This is especially true when the device requires the formation of homoepitaxial layers. While ZnSe is commercially available, it is at present extremely expensive due to the difficulty of growing single crystal boules with low impurity content and the resultant low yields. Many researchers have found it necessary to heat treat the crystals in liquid Zn in order to remove the impurities, lower the resistivity and activate the photoluminescence at room temperature. The physical vapor transport method (PVT) has been successfully used at MSFC to grow many single crystals of II-VI semiconducting materials including ZnSe. The main goal at NASA has been to try to establish the effect of gravity on the growth parameters. To this effect, crystals have been grown vertically upwards or horizontally. Both (111) and (110) oriented ZnSe crystals have been obtained via unseeded PVT growth. Preliminary characterization of the horizontally grown crystals has revealed that Cu is a major impurity and that the low temperature photoluminescence spectra is dominated by the copper peak. The ratio of the copper peak to the free exciton peak is being used to determine variations in composition throughout the crystal. It was the intent of this project to map the copper composition of various crystals via photoluminescence first, then measure their electrical resistivity and capacitance as a function of frequency before proceeding with a heat treatment designed to remove the copper impurities. However, equipment difficulties with the photoluminescence set up, having to establish a procedure for measuring the electrical properties of the as-grown crystals and time limitations made us re-evaluate the project goals. Vertically grown samples designated as ZnSe-25 were chosen to be measured electrically since they were not expected to show as much variation in their

  11. SINGLE CRYSTAL CADMIUM SULFIDE AND CADMIUM SELENIDE INSULATED-GATE FIELD-EFFECT TRIODES.

    DTIC Science & Technology

    Insulated-gate field-effect triodes were fabricated on single crystal cadmium sulfide and cadmium selenide . Both bulk crystals and platelets were...used for single crystal samples. Chromium and aluminum were found to make low impedance contacts to cadmium sulfide and cadmium selenide . The...polycrystalline cadmium sulfide and cadmium selenide IGFET’s. The characteristics of the fabricated devices were unstable with respect to time and temperature

  12. Investigation of adatom adsorption on single layer buckled germanium selenide

    NASA Astrophysics Data System (ADS)

    Arkın, H.; Aktürk, E.

    2016-12-01

    A recent study of Hu et al. [1] predicted that 2D single layer of asymmetric washboard germanium selenide is found to be stable and display semiconducting properties. Motivating from this study, we have shown that another phase, which is 2D buckled honeycomb germanium selenide, is also stable. This phase exhibits semiconducting behavior with a band gap of 2.29 eV. Furthermore, on the basis of the first principles, spin-polarized density functional calculations, we investigate the effect of selected adatoms adsorption on the b-GeSe single layer. The adatoms Se, Ge, S, Si, C, Br and P are chemisorbed with significant binding energy where this effects modify the electronic structure of the single layer buckled GeSe locally by tuning the band gap. Net integer magnetic moment can be achieved and b-GeSe attains half metallicity through the adsorption of Si, Ge, P and Br.

  13. Selenide-Based Electrocatalysts and Scaffolds for Water Oxidation Applications.

    PubMed

    Xia, Chuan; Jiang, Qiu; Zhao, Chao; Hedhili, Mohamed N; Alshareef, Husam N

    2016-01-06

    Selenide-based electrocatalysts and scaffolds on carbon cloth are successfully fabricated and demonstrated for enhanced water oxidation applications. A max-imum current density of 97.5 mA cm(-2) at an overpotential of a mere 300 mV and a small Tafel slope of 77 mV dec(-1) are achieved, suggesting the potential of these materials to serve as advanced oxygen evolution reaction catalysts.

  14. Mono and digallium selenide clusters as potential superhalogens.

    PubMed

    Seeburrun, Neelum; Archibong, Edet F; Ramasami, Ponnadurai

    2015-03-01

    We present a systematic theoretical study on mono and digallium selenide clusters, Ga(m)Se(n) (m = 1, 2 and n  =  1-4), along with their negatively and positively charged counterparts. Different theoretical methods, namely density functional theory (DFT), second-order Møller-Plesset perturbation theory (MP2) and coupled cluster singles and doubles, including non-iterative triples [CCSD(T)], were employed in conjunction with the 6-311+G(2df) basis set. The lowest-energy configurations of gallium selenides prefer to be planar, with the exception of cationic GaSe4 and Ga2Se4. The adiabatic electron affinities (AEA) of Ga(m)Se(n) (m = 1, 2 and n  = 1-4) clusters range from 1.07 to 3.78 eV, and their adiabatic ionization potentials (AIP) vary from 7.57 to 8.76 eV using the CCSD(T)//B3LYP level of theory. It was found that the AEAs of gallium selenides do not depend solely on the electrophilicity of the clusters but also on their electronic structures. No significant trend was observed in the AIP values and HOMO-LUMO (H-L) gaps with increase in cluster size of the mono and digallium selenide series. Among the dissociation channels, the decomposition of GaSe4 → GaSe2 + Se2 was found to be thermodynamically most favored. Furthermore, the AEAs of GaSe2, GaSe3, GaSe4 and Ga2Se4 were found to exceed that of the chlorine atom and are therefore termed as 'superhalogens'. Finally, the AEAs of the Ga2X(n) (X = O-Se; n = 2-4) series were found to be almost similar.

  15. Electron beam assisted synthesis of cadmium selenide nanomaterials

    SciTech Connect

    Rath, M. C.; Guleria, A.; Singh, S.; Singh, A. K.; Adhikari, S.; Sarkar, S. K.

    2013-02-05

    Cadmium selenide nanomaterials of various shapes and sizes have been synthesized in different condensed media through electron beam irradiation using a 7 MeV linear accelerator. The microstructures in different media as well as the presence of capping reagents play a crucial role in the formation of nanomaterials of different shapes and sizes. Their optical properties could be efficiently tuned by controlling the synthetic parameters.

  16. Synthesis of cadmium selenide colloidal quantum dots in aquatic medium

    NASA Astrophysics Data System (ADS)

    Mazing, D. S.; Matyushkin, L. B.; Aleksandrova, O. A.; Mikhailov, I. I.; Moshnikov, V. A.; Tarasov, S. A.

    2014-12-01

    Cadmium selenide nanocrystals were prepared in water phase through facile wet chemistry technique with thioglycolic acid (TGA) acting as capping agent. Structures were characterized using X-ray diffraction (XRD), UV-vis absorption and photoluminescence spectroscopies. Depending on synthesis conditions nanoparticles exhibit photoluminescence with maximum in the region of 580 - 680 nm. Influence of technological parameters and component concentrations on nanocrystals average size and properties was studied.

  17. The unexpected properties of alkali metal iron selenide superconductors

    SciTech Connect

    Dagotto, Elbio R

    2013-01-01

    The iron-based superconductors that contain FeAs layers as the fundamental building block in the crystal structures have been rationalized in the past using ideas based on the Fermi surface nesting of hole and electron pockets when in the presence of weak Hubbard U interactions. This approach seemed appropriate considering the small values of the magnetic moments in the parent compounds and the clear evidence based on photoemission experiments of the required electron and hole pockets. However, recent results in the context of alkali metal iron selenides, with generic chemical composition AxFe2ySe2 (A alkali metal element), have challenged those previous ideas since at particular compositions y the low-temperature ground states are insulating and display antiferromagnetic order with large iron magnetic moments. Moreover, angle-resolved photoemission studies have revealed the absence of hole pockets at the Fermi level in these materials. The present status of this exciting area of research, with the potential to alter conceptually our understanding of the ironbased superconductors, is here reviewed, covering both experimental and theoretical investigations. Other recent related developments are also briefly reviewed, such as the study of selenide two-leg ladders and the discovery of superconductivity in a single layer of FeSe. The conceptual issues considered established for the alkali metal iron selenides, as well as several issues that still require further work, are discussed.

  18. Isomorphism and solid solutions among Ag- and Au-selenides

    NASA Astrophysics Data System (ADS)

    Palyanova, Galina A.; Seryotkin, Yurii V.; Kokh, Konstantin A.; Bakakin, Vladimir V.

    2016-09-01

    Au-Ag selenides were synthesized by heating stoichiometric mixtures of elementary substances of initial compositions Ag2-xAuxSe with a step of x=0.25 (0≤x≤2) to 1050 °C and annealing at 500 °C. Scanning electron microscopy, optical microscopy, electron microprobe analysis and X-ray powder diffraction methods have been applied to study synthesized samples. Results of studies of synthesized products revealed the existence of three solid solutions with limited isomorphism Ag↔Au: naumannite Ag2Se - Ag1.94Au0.06Se, fischesserite Ag3AuSe2 - Ag3.2Au0.8Se2 and gold selenide AuSe - Au0.94Ag0.06Se. Solid solutions and AgAuSe phases were added to the phase diagram of Ag-Au-Se system. Crystal-chemical interpretation of Ag-Au isomorphism in selenides was made on the basis of structural features of fischesserite, naumannite, and AuSe.

  19. Determination of the homogeneity region of cadmium selenide

    SciTech Connect

    Brezhnev, V.Yu.; Kharif, Ya.L.; Kovtunenko, P.V.

    1987-10-01

    The purpose of the authors paper is refinement of the limit of the homogeneity region of cadmium selenide. The method of extraction of cadmium into the vapor phase was used to determine the cadmium content in cadmium selenide. At 870/sup 0/K the equilibrium of the cadmium selenide crystals during saturation by cadmium was monitored according to the reproducibility (in the range of +/-15%) of the results of experiments of different durations (30, 46, 62, and 192 h). Since at 870/sup 0/K the equilibrium was established in 30 h, at higher temperatures the duration of the annealing was assumed to be 30 h. In addition, in experiments at 1270 and 1370 K, crystals with thicknesses from 200 to 1500 ..mu..m were saturated simultaneously. The solubility of cadmium in CdSe was found to be 0.00053-0.00071 at. % at 870/sup 0/K, 0.0073-0.0113 at. % at 1170/sup 0/K, 0.022 at. % at 1270 K, 0.038 at. % at 1320/sup 0/K, and 0.044 at. % at 1370/sup 0/K.itrified

  20. Sodium selenide toxicity is mediated by O2-dependent DNA breaks.

    PubMed

    Peyroche, Gérald; Saveanu, Cosmin; Dauplais, Marc; Lazard, Myriam; Beuneu, François; Decourty, Laurence; Malabat, Christophe; Jacquier, Alain; Blanquet, Sylvain; Plateau, Pierre

    2012-01-01

    Hydrogen selenide is a recurrent metabolite of selenium compounds. However, few experiments studied the direct link between this toxic agent and cell death. To address this question, we first screened a systematic collection of Saccharomyces cerevisiae haploid knockout strains for sensitivity to sodium selenide, a donor for hydrogen selenide (H(2)Se/HSe(-/)Se(2-)). Among the genes whose deletion caused hypersensitivity, homologous recombination and DNA damage checkpoint genes were over-represented, suggesting that DNA double-strand breaks are a dominant cause of hydrogen selenide toxicity. Consistent with this hypothesis, treatment of S. cerevisiae cells with sodium selenide triggered G2/M checkpoint activation and induced in vivo chromosome fragmentation. In vitro, sodium selenide directly induced DNA phosphodiester-bond breaks via an O(2)-dependent reaction. The reaction was inhibited by mannitol, a hydroxyl radical quencher, but not by superoxide dismutase or catalase, strongly suggesting the involvement of hydroxyl radicals and ruling out participations of superoxide anions or hydrogen peroxide. The (•)OH signature could indeed be detected by electron spin resonance upon exposure of a solution of sodium selenide to O(2). Finally we showed that, in vivo, toxicity strictly depended on the presence of O(2). Therefore, by combining genome-wide and biochemical approaches, we demonstrated that, in yeast cells, hydrogen selenide induces toxic DNA breaks through an O(2)-dependent radical-based mechanism.

  1. A one-step synthesis of cadmium selenide quantum dots from a novel single source precursor.

    PubMed

    Crouch, D J; O'Brien, P; Malik, M A; Skabara, P J; Wright, S P

    2003-06-21

    A new approach to the one-step synthesis of cadmium selenide (CdSe) quantum dots is reported using the air stable complex cadmium imino-bis(diisopropylphosphine selenide); the ligand is readily prepared from elemental selenium and the precursor, quantum dots of comparable quality to those prepared by conventional methods are obtained.

  2. Characterization of the Interface Energetics for N-Type Cadmium Selenide/Non-Aqueous Electrolyte Junctions.

    DTIC Science & Technology

    1982-08-27

    nocesOMY and Idnnti by block number) 3 Photoelectrochemistry, interfaces, photoanodes, cadmium selenide , Ii non-aqueous electrolyte junctions 82 09 1 6 00 5...REPORT NO. 35 "CHARACTERIZATION OF THE INTERFACE ENERGETICS FOR N-TYPE CADMIUM SELENIDE /NON-AQUEOUS ELECTROLYTE JUNCTIONS" by A. Aruchamy, James A

  3. Luminescent Photoelectrochemical Cells. 6. Spatial Aspects of the Photoluminescence and Electroluminescence of Cadmium Selenide Electrodes.

    DTIC Science & Technology

    1981-10-06

    NO. 8 Luminescent Photoelectrochemical Cells. 6. Spatial Aspects of the Photoluminescence and Electroluminescence of Cadmium Selenide Electrodes by...Photoelectrochemistry; photoluminescence; electroluminescence; cadmium selenide electrodes 20. ABSTRACT (Continue. on reverse aide flnocosee7 and...REPORT A PERIOD COVERED Luminescent Photoelectrochemical Cells. 6.1 1 Spatial Aspects of the Photoluminescence and Elect roluminescence of Cadmium

  4. Organoselenium bis selenide attenuates 3-nitropropionic acid-induced neurotoxicity in rats.

    PubMed

    Bortolatto, Cristiani F; Jesse, Cristiano R; Wilhelm, Ethel A; Chagas, Pietro M; Nogueira, Cristina W

    2013-04-01

    This study was designed to evaluate the effects of bis selenide on Huntington disease (HD)-like signs induced by 3-nitropropionic acid (3-NP) in rats. To this aim, rats were treated for 4 days with bis selenide (5 or 20 mg/kg/day, per oral) 30 min before 3-NP (20 mg/kg/day, intraperitoneally). The body weight gain, locomotor activity, motor coordination, and biochemical parameters in striatal preparations were assessed 24 h after the last injection of 3-NP. The highest dose of bis selenide was effective in protecting against body weight loss and motor coordination deficit induced by 3-NP. The impairment of locomotor activity caused by 3-NP was abolished by bis selenide at both doses. Bis selenide (5 and 20 mg/kg) partially restored succinate dehydrogenase activity inhibited after 3-NP exposure. The dose of 20 mg/kg of bis selenide recovered partially δ-aminolevulinic acid dehydratase activity, and totally Na(+), K(+)-ATPase activity, two sulfhydryl enzymes sensitive to oxidizing agents, which had their activities inhibited by 3-NP. Also, 3-NP led to an increase in protein carbonyl levels and glutathione reductase activity and inhibited catalase activity-alterations that were reversed by bis selenide administration at both doses. The highest dose of bis selenide was effective against the increase of RS levels, the depletion of reduced glutathione content, and the inhibition of glutathione peroxidase activity induced by 3-NP. Bis selenide was not effective against inhibition of SOD activity caused by 3-NP. These findings demonstrate that bis selenide elicited protective effects against HD-like signs induced by 3-NP in rats.

  5. Nanoscale Inhomogeneities Mapping in Ga-Modified Arsenic Selenide Glasses.

    PubMed

    Shpotyuk, Ya; Adamiak, S; Dziedzic, A; Szlezak, J; Bochnowski, W; Cebulski, J

    2017-12-01

    Nanoscale inhomogeneities mapping in Ga-modified As2Se3 glass was utilized exploring possibilities of nanoindentation technique using a Berkovitch-type diamond tip. Structural inhomogeneities were detected in Gax(As0.40Se0.60)100-x alloys with more than 3 at.% of Ga. The appeared Ga2Se3 nanocrystallites were visualized in Ga-modified arsenic selenide glasses using scanning and transmission electron microscopy. The Ga additions are shown to increase nanohardness and Young's modulus, this effect attaining an obvious bifurcation trend in crystallization-decomposed Ga5(As0.40Se0.60)95 alloy.

  6. Characterization of Zinc Selenide-Based Ultraviolet Detectors

    DTIC Science & Technology

    2009-12-01

    0.67 Silicon carbide SiC 2.86 Aluminum nitride AlN 6.3 Diamond C 5.5 Gallium(III) arsenide GaAs 1.43 Gallium(III) nitride GaN 3.4 Indium(III...photosensitivity compared to silicon -based detectors due to its larger bandgap. Its capability of turning optical power into valuable electrical signals...such as Zinc Selenide (ZnSe) have become popular for ultraviolet (UV) photodetectors. ZnSe has a higher photosensitivity compared to silicon -based

  7. Luminescence and photoconductivity of high-purity cadmium selenide

    SciTech Connect

    Martynov, V.N.

    1995-10-01

    Slightly off-stoichlometric high-purity cadmium and zinc chalcogenides are used as high-efficiency sensors in various optoelectronic devices. The procedure for preparing high-purity chalcogenides was described elsewhere. Such materials (wurtzite-type structure, sp. gr. C{sup 4}{sub 6v}) exhibit exciton luminescence and the photoconductivity associated with the A-, B-, and C-excitonic series over a wide temperature range. In this work, we studied the luminescence and photoconductivity (PC) of cadmium selenide prepared as described.

  8. Copper hypersensitivity.

    PubMed

    Fage, Simon W; Faurschou, Annesofie; Thyssen, Jacob P

    2014-10-01

    The world production of copper is steadily increasing. Although humans are widely exposed to copper-containing items on the skin and mucosa, allergic reactions to copper are only infrequently reported. To review the chemistry, biology and accessible data to clarify the implications of copper hypersensitivity, a database search of PubMed was performed with the following terms: copper, dermatitis, allergic contact dermatitis, contact hypersensitivity, contact sensitization, contact allergy, patch test, dental, IUD, epidemiology, clinical, and experimental. Human exposure to copper is relatively common. As a metal, it possesses many of the same qualities as nickel, which is a known strong sensitizer. Cumulative data on subjects with presumed related symptoms and/or suspected exposure showed that a weighted average of 3.8% had a positive patch test reaction to copper. We conclude that copper is a very weak sensitizer as compared with other metal compounds. However, in a few and selected cases, copper can result in clinically relevant allergic reactions.

  9. Fractal simulation of the resistivity and capacitance of arsenic selenide

    SciTech Connect

    Balkhanov, V. K. Bashkuev, Yu. B.

    2010-03-15

    The temperature dependences of the ac resistivity R and ac capacitance C of arsenic selenide were measured more than four decades ago [V. I. Kruglov and L. P. Strakhov, in Problems of Solid State Electronics, Vol. 2 (Leningrad Univ., Leningrad, 1968)]. According to these measurements, the frequency dependences are R {proportional_to} {omega}{sup -0.80{+-}0.01} and {Delta}C {proportional_to} {omega}{sup -0.120{+-}0.006} ({omega} is the circular frequency and {Delta}C is measured from the temperature-independent value C{sub 0}). According to fractal-geometry methods, R {proportional_to} {omega}{sup 1-3/h} and {Delta}C {proportional_to} {omega}{sup -2+3/h}, where h is the walk dimension of the electric current in arsenic selenide. Comparison of the experimental and theoretical results indicates that the walk dimensions calculated from the frequency dependences of resistivity and capacitance are h{sub R} = 1.67 {+-} 0.02 and h{sub C} = 1.60 {+-} 0.08, which are in agreement with each other within the measurement errors. The fractal dimension of the distribution of conducting sections is D = 1/h = 0.6. Since D < 1, the conducting sections are spatially separated and form a Cantor set.

  10. Enhanced photo catalytic performance of nickel doped bismuth selenide under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Kulsi, Chiranjit; Ghosh, Amrita; Mondal, Anup; Kargupta, Kajari; Ganguly, Saibal; Banerjee, Dipali

    2017-03-01

    We have reported photo catalytic properties of bismuth selenide (Bi2Se3) and nickel doped (5 mol%) bismuth selenide (Bi2Se3) samples on two different dyes, congo red (CR) and rose bengal (RB) under visible-light irradiation without and with hydrogen peroxide. A maximum rate constant of 0.0365 min‑1 for RB dye has been observed for the nickel doped bismuth selenide catalyst in presence of hydrogen peroxide. A possible mechanism for improvement of photo catalytic performance has been explained based on band structure.

  11. Copper transport.

    PubMed

    Linder, M C; Wooten, L; Cerveza, P; Cotton, S; Shulze, R; Lomeli, N

    1998-05-01

    In adult humans, the net absorption of dietary copper is approximately 1 mg/d. Dietary copper joins some 4-5 mg of endogenous copper flowing into the gastrointestinal tract through various digestive juices. Most of this copper returns to the circulation and to the tissues (including liver) that formed them. Much lower amounts of copper flow into and out of other major parts of the body (including heart, skeletal muscle, and brain). Newly absorbed copper is transported to body tissues in two phases, borne primarily by plasma protein carriers (albumin, transcuprein, and ceruloplasmin). In the first phase, copper goes from the intestine to the liver and kidney; in the second phase, copper usually goes from the liver (and perhaps also the kidney) to other organs. Ceruloplasmin plays a role in this second phase. Alternatively, liver copper can also exit via the bile, and in a form that is less easily reabsorbed. Copper is also present in and transported by other body fluids, including those bathing the brain and central nervous system and surrounding the fetus in the amniotic sac. Ceruloplasmin is present in these fluids and may also be involved in copper transport there. The concentrations of copper and ceruloplasmin in milk vary with lactational stage. Parallel changes occur in ceruloplasmin messenger RNA expression in the mammary gland (as determined in pigs). Copper in milk ceruloplasmin appears to be particularly available for absorption, at least in rats.

  12. Exploring the thermoelectric and magnetic properties of uranium selenides: Tl2Ag2USe4 and Tl3Cu4USe6

    NASA Astrophysics Data System (ADS)

    Azam, Sikander; Khan, Saleem Ayaz; Din, Haleem Ud; Khenata, Rabah; Goumri-Said, Souraya

    2016-09-01

    The electronic, magnetic and thermoelectric properties of Tl2Ag2USe4 and Tl3Cu4USe6 compounds were investigated using the full potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). The exchange correlation was treated with the generalized gradient approximation plus optimized effective Hubbard parameter and spin-orbit coupling (GGA+U+SOC). The present uranium selenides show narrow direct energy band gap values of 0.7 and 0.875 eV for Tl2Ag2USe4 and Tl3Cu4USe6 respectively. For both selenides U-d/f states are responsible for electrical transport properties. Uranium atoms were the most contributors in the magnetic moment compared to other atoms and show ferromagnetic nature. The spin density isosurfaces show the polarization of neighboring atoms of Uranium, such as silver/copper and selenium. Thermoelectric calculations reveal that Tl3Cu4USe6 is more suitable for thermoelectric device applications than Tl2Ag2USe4.

  13. Non-Stoichiometric Amorphous Indium Selenide Thin Films as a Buffer Layer for CIGS Solar Cells with Various Temperatures in Rapid Thermal Annealing.

    PubMed

    Yoo, Myoung Han; Kim, Nam-Hoon

    2016-05-01

    The conventional structure of most of copper indium gallium diselenide (Culn(1-x)Ga(x)Se2, CIGS) solar cells includes a CdS thin film as a buffer layer. Cd-free buffer layers have attracted great interest for use in photovoltaic applications to avoid the use of hazardous and toxic materials. The RF magnetron sputtering method was used with an InSe2 compound target to prepare the indium selenide precursor. Rapid thermal annealing (RTA) was conducted in ambient N2 gas to control the concentration of volatile Se from the precursor with a change in temperature. The nature of the RTA-treated indium selenide thin films remained amorphous under annealing temperatures of ≤ 700 degrees C. The Se concentration of the RTA-treated specimens demonstrated an opposite trend to the annealing temperature. The optical transmittance and band gap energies were 75.33% and 2.451-3.085 eV, respectively, and thus were suitable for the buffer layer. As the annealing temperature increased, the resistivity decreased by an order-of-magnitude from 10(4) to 10(1) Ω-cm. At lower Se concentrations, the conductivity abruptly changed from p-type to n-type without crystallite formation in the amorphous phase, with the carrier concentration in the order of 10(17) cm(-3).

  14. Green Hydroselenation of Aryl Alkynes: Divinyl Selenides as a Precursor of Resveratrol.

    PubMed

    Perin, Gelson; Barcellos, Angelita M; Luz, Eduardo Q; Borges, Elton L; Jacob, Raquel G; Lenardão, Eder J; Sancineto, Luca; Santi, Claudio

    2017-02-20

    A simple and efficient protocol to prepare divinyl selenides has been developed by the regio- and stereoselective addition of sodium selenide species to aryl alkynes. The nucleophilic species was generates in situ, from the reaction of elemental selenium with NaBH₄, utilizing PEG-400 as the solvent. Several divinyl selenides were obtained in moderate to excellent yields with selectivity for the (Z,Z)-isomer by a one-step procedure that was carried out at 60 °C in short reaction times. The methodology was extended to tellurium, giving the desired divinyl tellurides in good yields. Furthermore, the Fe-catalyzed cross-coupling reaction of bis(3,5-dimethoxystyryl) selenide 3f with (4-methoxyphenyl)magnesium bromide 5 afforded resveratrol trimethyl ether 6 in 57% yield.

  15. The use of 4-substituted pyridines to afford amphiphilic, pegylated cadmium selenide nanoparticles.

    PubMed

    Skaff, Habib; Emrick, Todd

    2003-01-07

    Amphiphilic cadmium selenide (CdSe) nanoparticles were prepared by surface functionalization with novel ligands 1 and 2, composed of pyridine moieties substituted in the 4-position with polyethylene glycol (PEG) chains.

  16. Growth of zinc selenide crystals by physical vapor transport in microgravity

    NASA Technical Reports Server (NTRS)

    Rosenberger, Franz

    1995-01-01

    The growth of single crystals of zinc selenide was carried out by both closed ampoule physical vapor transport and effusive ampoule physical vapor transport (EAPVT). The latter technique was shown to be a much more efficient method for the seeded growth of zinc selenide, resulting in higher transport rates. Furthermore, EAPVT work on CdTe has shown that growth onto /n11/ seeds is advantageous for obtaining reduced twinning and defect densities in II-VI sphalerite materials.

  17. Hollow Cobalt Selenide Microspheres: Synthesis and Application as Anode Materials for Na-Ion Batteries.

    PubMed

    Ko, You Na; Choi, Seung Ho; Kang, Yun Chan

    2016-03-01

    The electrochemical properties of hollow cobalt oxide and cobalt selenide microspheres are studied for the first time as anode materials for Na-ion batteries. Hollow cobalt oxide microspheres prepared by one-pot spray pyrolysis are transformed into hollow cobalt selenide microspheres by a simple selenization process using hydrogen selenide gas. Ultrafine nanocrystals of Co3O4 microspheres are preserved in the cobalt selenide microspheres selenized at 300 °C. The initial discharge capacities for the Co3O4 and cobalt selenide microspheres selenized at 300 and 400 °C are 727, 595, and 586 mA h g(-1), respectively, at a current density of 500 mA g(-1). The discharge capacities after 40 cycles for the same samples are 348, 467, and 251 mA h g(-1), respectively, and their capacity retentions measured from the second cycle onward are 66, 91, and 50%, respectively. The hollow cobalt selenide microspheres have better rate performances than the hollow cobalt oxide microspheres.

  18. Role of O and Se defects in the thermoelectric properties of bismuth oxide selenide

    NASA Astrophysics Data System (ADS)

    Van Quang, Tran; Kim, Miyoung

    2016-11-01

    Bismuth oxygen selenide, Bi2O2Se, is a promising thermoelectric material because of its reduced thermal conductivity. In this study, we perform the first-principles calculation and utilize the solution of Boltzmann transport equation in a constant relaxation-time approximation to compute the electronic and thermoelectric properties of Bi2O2Se with O and Se defects. Oxygen vacancies trap bands located inside the band gap of Bi2O2Se, and the compound becomes a conductor. These bands lead to drastic reduction in the Seebeck coefficient. When vacancies are filled by selenide atoms (selenide point defect), the materials return to be a semiconductor and the Seebeck coefficient increases. The increase of S is also found in the system with defects formed by the substitution of oxygen atoms into selenide sites (oxygen point defect) in the pristine compound. The power factor significantly increases during p-type doping compared with that during n-type doping for the selenide point defect. However, differences in the two doping cases are less distinguished for the oxygen point defect. Hence, the selenide point defect, Bi2O2-δSe1+δ with p-type doping, is an effective way to increase the power factor and eventually the thermoelectric efficiency of Bi2O2Se.

  19. Synthesis and characterization of luminescent aluminium selenide nanocrystals

    SciTech Connect

    Balitskii, O.A.; Demchenko, P.Yu.; Mijowska, E.; Cendrowski, K.

    2013-02-15

    Highlights: ► Synthesis procedure of size and sharp controlled Al{sub 2}Se{sub 3} nanocrystals is introduced. ► Obtained nanoparticles are highly crystalline of hexagonal wurtzite type. ► Colloidal Al{sub 2}Se{sub 3} nanocrystals are highly luminescent in the near UV spectral region. ► They can be implemented in light emitters/collectors, concurring with II–VI nanodots. -- Abstract: We propose the synthesis and characterization of colloidal aluminium selenide nanocrystals using trioctylphosphine as a solvent. The nanoparticles have several absorption bands in the spectral region 330–410 nm and are bright UV-blue luminescent, which is well demanded in light collecting and emitting devices, e.g. for tuning their spectral characteristics to higher energy solar photons.

  20. Facile synthesis of cadmium selenide nanowires and their optical properties

    NASA Astrophysics Data System (ADS)

    Du, Yinxiao; Li, Guang-cheng

    2011-02-01

    Well crystalline cadmium selenide (CdSe) nanowires were fabricated on the composite layer of gold and carbon coated Si substrates by a facile chemical vapor deposition method. These nanowires are of single-crystalline hexagonal structure and the average length is up to tens of micrometers. The growth process follows a typical vapor-liquid-solid (VLS) mechanism, and the carbon layer can distinctly enhance the VLS process of the CdSe nanowires. The cathodoluminescence (CL) spectrum of an individual nanowire reveals a strong near-band-edge (NBE) emission and relative weak infrared emission centered at 710 and 981 nm, respectively. The defects-related infrared emission is ascribed to the deep defect donors-related energy level induced by a large amount of Se vacancies.

  1. In situ transmission electron microscopy of cadmium selenide nanorod sublimation

    SciTech Connect

    Hellebusch, Daniel J.; Manthiram, Karthish; Beberwyck, Brandon J.; Alivisatos, A. Paul

    2015-01-23

    In situ electron microscopy is used to observe the morphological evolution of cadmium selenide nanorods as they sublime under vacuum at a series of elevated temperatures. Mass loss occurs anisotropically along the nanorod’s long axis. At temperatures close to the sublimation threshold, the phase change occurs from both tips of the nanorods and proceeds unevenly with periods of rapid mass loss punctuated by periods of relative stability. At higher temperatures, the nanorods sublime at a faster, more uniform rate, but mass loss occurs from only a single end of the rod. Furthermore, we propose a mechanism that accounts for the observed sublimation behavior based on the terrace–ledge–kink (TLK) model and how the nanorod surface chemical environment influences the kinetic barrier of sublimation.

  2. Electrochemical synthesis of alkali-intercalated iron selenide superconductors

    NASA Astrophysics Data System (ADS)

    Shen, Shi-Jie; Ying, Tian-Ping; Wang, Gang; Jin, Shi-Feng; Zhang, Han; Lin, Zhi-Ping; Chen, Xiao-Long

    2015-11-01

    Electrochemical method has been used to insert K/Na into FeSe lattice to prepare alkali-intercalated iron selenides at room temperature. Magnetization measurement reveals that KxFe2Se2 and NaxFe2Se2 are superconductive at 31 K and 46 K, respectively. This is the first successful report of obtaining metal-intercalated FeSe-based high-temperature superconductors using electrochemical method. It provides an effective route to synthesize metal-intercalated layered compounds for new superconductor exploration. Project supported by the National Natural Science Foundation of China (Grant Nos. 51322211and 91422303), the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB07020100), Beijing Nova Program of China (Grant No. 2011096), and K. C. Wong Education Foundation, Hong Kong, China.

  3. Manipulation of cadmium selenide nanorods with an atomic force microscope.

    PubMed

    Tranvouez, E; Orieux, A; Boer-Duchemin, E; Devillers, C H; Huc, V; Comtet, G; Dujardin, G

    2009-04-22

    We have used an atomic force microscope (AFM) to manipulate and study ligand-capped cadmium selenide nanorods deposited on highly oriented pyrolitic graphite (HOPG). The AFM tip was used to manipulate (i.e., translate and rotate) the nanorods by applying a force perpendicular to the nanorod axis. The manipulation result was shown to depend on the point of impact of the AFM tip with the nanorod and whether the nanorod had been manipulated previously. Forces applied parallel to the nanorod axis, however, did not give rise to manipulation. These results are interpreted by considering the atomic-scale interactions of the HOPG substrate with the organic ligands surrounding the nanorods. The vertical deflection of the cantilever was recorded during manipulation and was combined with a model in order to estimate the value of the horizontal force between the tip and nanorod during manipulation. This horizontal force is estimated to be on the order of a few tens of nN.

  4. Nanopatterned cadmium selenide Langmuir-Blodgett platform for leukemia detection.

    PubMed

    Sharma, Aditya; Pandey, Chandra M; Matharu, Zimple; Soni, Udit; Sapra, Sameer; Sumana, Gajjala; Pandey, Manoj K; Chatterjee, Tathagat; Malhotra, Bansi D

    2012-04-03

    We present results of the studies relating to preparation of Langmuir-Blodgett (LB) monolayers of tri-n-octylphosphine oxide-capped cadmium selenide quantum dots (QCdSe) onto indium-tin oxide (ITO) coated glass substrate. The monolayer behavior has been studied at the air-water interface under various subphase conditions. This nanopatterned platform has been explored to fabricate an electrochemical DNA biosensor for detection of chronic myelogenous leukemia (CML) by covalently immobilizing the thiol-terminated oligonucleotide probe sequence via a displacement reaction. The results of electrochemical response studies reveal that this biosensor can detect target DNA in the range of 10(-6) to 10(-14) M within 120 s, has a shelf life of 2 months, and can be used about 8 times. Further, this nucleic acid sensor has been found to distinguish the CML-positive and the control negative clinical patient samples.

  5. In Situ Transmission Electron Microscopy of Cadmium Selenide Nanorod Sublimation.

    PubMed

    Hellebusch, Daniel J; Manthiram, Karthish; Beberwyck, Brandon J; Alivisatos, A Paul

    2015-02-19

    In situ electron microscopy is used to observe the morphological evolution of cadmium selenide nanorods as they sublime under vacuum at a series of elevated temperatures. Mass loss occurs anisotropically along the nanorod's long axis. At temperatures close to the sublimation threshold, the phase change occurs from both tips of the nanorods and proceeds unevenly with periods of rapid mass loss punctuated by periods of relative stability. At higher temperatures, the nanorods sublime at a faster, more uniform rate, but mass loss occurs from only a single end of the rod. We propose a mechanism that accounts for the observed sublimation behavior based on the terrace-ledge-kink (TLK) model and how the nanorod surface chemical environment influences the kinetic barrier of sublimation.

  6. Hierarchically structured porous cadmium selenide polycrystals using polystyrene bilayer templates.

    PubMed

    Park, Jin Young; Hendricks, Nicholas R; Carter, Kenneth R

    2012-09-18

    In this study, a novel approach is demonstrated to fabricate hierarchically structured cadmium selenide (CdSe) layers with size-tunable nano/microporous morphologies achieved using polystyrene (PS) bilayered templates (top layer: colloidal template) via potentiostatic electrochemical deposition. The PS bilayer template is made in two steps. First, various PS patterns (stripes, ellipsoids, and circles) are prepared as the bottom layers through imprint lithography. In a second step, a top template is deposited that consists of a self-assembled layer of colloidal 2D packed PS particles. Electrochemical growth of CdSe crystals in the voids and selective removal of the PS bilayered templates give rise to hierarchically patterned 2D hexagonal porous CdSe structures. This simple and facile technique provides various unconventional porous CdSe films, arising from the effect of the PS bottom templates.

  7. In situ transmission electron microscopy of cadmium selenide nanorod sublimation

    DOE PAGES

    Hellebusch, Daniel J.; Manthiram, Karthish; Beberwyck, Brandon J.; ...

    2015-01-23

    In situ electron microscopy is used to observe the morphological evolution of cadmium selenide nanorods as they sublime under vacuum at a series of elevated temperatures. Mass loss occurs anisotropically along the nanorod’s long axis. At temperatures close to the sublimation threshold, the phase change occurs from both tips of the nanorods and proceeds unevenly with periods of rapid mass loss punctuated by periods of relative stability. At higher temperatures, the nanorods sublime at a faster, more uniform rate, but mass loss occurs from only a single end of the rod. Furthermore, we propose a mechanism that accounts for themore » observed sublimation behavior based on the terrace–ledge–kink (TLK) model and how the nanorod surface chemical environment influences the kinetic barrier of sublimation.« less

  8. Formation and Reactivity of Organo-Functionalized Tin Selenide Clusters.

    PubMed

    Rinn, Niklas; Eußner, Jens P; Kaschuba, Willy; Xie, Xiulan; Dehnen, Stefanie

    2016-02-24

    Reactions of R(1) SnCl3 (R(1) =CMe2 CH2 C(O)Me) with (SiMe3 )2 Se yield a series of organo-functionalized tin selenide clusters, [(SnR(1) )2 SeCl4 ] (1), [(SnR(1) )2 Se2 Cl2 ] (2), [(SnR(1) )3 Se4 Cl] (3), and [(SnR(1) )4 Se6 ] (4), depending on the solvent and ratio of the reactants used. NMR experiments clearly suggest a stepwise formation of 1 through 4 by subsequent condensation steps with the concomitant release of Me3 SiCl. Furthermore, addition of hydrazines to the keto-functionalized clusters leads to the formation of hydrazone derivatives, [(Sn2 (μ-R(3) )(μ-Se)Cl4 ] (5, R(3) =[CMe2 CH2 CMe(NH)]2 ), [(SnR(2) )3 Se4 Cl] (6, R(2) =CMe2 CH2 C(NNH2 )Me), [(SnR(4) )3 Se4 ][SnCl3 ] (7, R(4) =CMe2 CH2 C(NNHPh)Me), [(SnR(2) )4 Se6 ] (8), and [(SnR(4) )4 Se6 ] (9). Upon treatment of 4 with [Cu(PPh3 )3 Cl] and excess (SiMe3 )2 Se, the cluster fragments to form [(R(1) Sn)2 Se2 (CuPPh3 )2 Se2 ] (10), the first discrete Sn/Se/Cu cluster compound reported in the literature. The derivatization reactions indicate fundamental differences between organotin sulfide and organotin selenide chemistry.

  9. Double-Diffusive Convection During Growth of Halides and Selenides

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Su, Ching-Hua; Duval, Walter M. B.

    2015-01-01

    Heavy metal halides and selenides have unique properties which make them excellent materials for chemical, biological and radiological sensors. Recently it has been shown that selenohalides are even better materials than halides or selenides for gamma-ray detection. These materials also meet the strong needs of a wide band imaging technology to cover ultra-violet (UV), midwave infrared wavelength (MWIR) to very long wavelength infrared (VLWIR) region for hyperspectral imager components such as etalon filters and acousto-optic tunable filters (AO). In fact AOTF based imagers based on these materials have some superiority than imagers based on liquid crystals, FTIR, Fabry-Perot, grating, etalon, electro-optic modulation, piezoelectric and several other concepts. For example, broadband spectral and imagers have problems of processing large amount of information during real-time observation. Acousto-Optic Tunable Filter (AOTF) imagers are being developed to fill the need of reducing processing time of data, low cost operation and key to achieving the goal of covering long-wave infrared (LWIR). At the present time spectral imaging systems are based on the use of diffraction gratings are typically used in a pushbroom or whiskbroom mode. They are mostly used in systems and acquire large amounts of hyperspectral data that is processed off-line later. In contrast, acousto-optic tunable filter spectral imagers require very little image processing, providing new strategies for object recognition and tracking. They are ideally suited for tactical situations requiring immediate real-time image processing. But the performance of these imagers depends on the quality and homogeneity of acousto-optic materials. In addition for many systems requirements are so demanding that crystals up to sizes of 10 cm length are desired. We have studied several selenides and halide crystals for laser and AO imagers for MWIR and LWIR wavelength regions. We have grown and fabricated crystals of

  10. Power Scaling Feasibility or Chromium-Doped II-VI Laser Sources and the Demonstration of a Chromium-Doped Zinc Selenide Face-Cooled Disk Laser

    DTIC Science & Technology

    2002-03-01

    hosts such as zinc selenide [1], cadmium selenide [2], cadmium manganese telluride[3], etc. results in laser materials with high quantum yield and...Zinc Selenide Face-Cooled Disk Laser DISSERTATION Jason B. McKay, Captain, USAF AFIT/DS/ENP/02-5 DEPARTMENT OF THE AIR FORCE AIR...SOURCES AND THE DEMONSTRATION OF A CHROMIUM-DOPED ZINC SELENIDE FACE- COOLED DISK LASER DISSERTATION Presented to the Faculty

  11. Design and Optimization of Copper Indium Gallium Selenide Thin Film Solar Cells

    DTIC Science & Technology

    2015-09-01

    7 1. Solar Spectrum and Wavelength Energy ....................................7 2. Photogeneration of Electron Hole Pairs...Expeditionary Energy Office GREENS Ground Renewable Expeditionary Energy System NPS Naval Postgraduate School SPACES Solar Portable Alternative...choice for an alternate energy source, as illustrated by the map in Figure 1. Figure 1. Global resource map showing solar intensity, from [4

  12. Synthesis of colloidal nanoscaled copper-indium-gallium-selenide (CIGS) particles for photovoltaic applications.

    PubMed

    Mousavi, S H; Müller, T S; de Oliveira, P W

    2012-09-15

    In this work, Cu(In,Ga)Se(2) (CIGS) nanoparticles were synthesized using a wet chemical method. The method is based on a non-vacuum thermal process that does not use selenization. The effects of temperature, source materials, and growth conditions on the phase and particle size were investigated. X-ray diffraction results confirm the formation of a tetragonal CIGS structure as the main phase with the purity more than 99% obtained by energy-dispersive X-ray spectroscopy (EDX). The morphology and size of the samples were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Using these methods, 20-80nm particles were obtained. Through measurements of the absorption spectra of CIGS nanoparticles, the band gap of the synthesized material was determined to be about 1.44eV, which corresponds to an acceptable wavelength region for absorber layers in solar cells.

  13. Copper indium gallium selenide (CIGS) photovoltaic devices made using multistep selenization of nanocrystal films.

    PubMed

    Harvey, Taylor B; Mori, Isao; Stolle, C Jackson; Bogart, Timothy D; Ostrowski, David P; Glaz, Micah S; Du, Jiang; Pernik, Douglas R; Akhavan, Vahid A; Kesrouani, Hady; Vanden Bout, David A; Korgel, Brian A

    2013-09-25

    The power conversion efficiency of photovoltaic devices made with ink-deposited Cu(InxGa1-x)Se2 (CIGS) nanocrystal layers can be enhanced by sintering the nanocrystals with a high temperature selenization process. This process, however, can be challenging to control. Here, we report that ink deposition followed by annealing under inert gas and then selenization can provide better control over CIGS nanocrystal sintering and yield generally improved device efficiency. Annealing under argon at 525 °C removes organic ligands and diffuses sodium from the underlying soda lime glass into the Mo back contact to improve the rate and quality of nanocrystal sintering during selenization at 500 °C. Shorter selenization time alleviates excessive MoSe2 formation at the Mo back contact that leads to film delamination, which in turn enables multiple cycles of nanocrystal deposition and selenization to create thicker, more uniform absorber films. Devices with power conversion efficiency greater than 7% are fabricated using the multiple step nanocrystal deposition and sintering process.

  14. Defect States in Copper Indium Gallium Selenide Solar Cells from Two-Wavelength Excitation Photoluminescence Spectroscopy

    SciTech Connect

    Jensen, Soren A.; Dippo, Patricia; Mansfield, Lorelle M.; Glynn, Stephen; Kuciauskas, Darius

    2016-11-21

    We use two-wavelength excitation photoluminescence spectroscopy to probe defect states in CIGS thin films. Above-Eg excitation is combined with a tunable IR bias light that modulates the population of the defect states. We find that IR illumination in the range of 1400-2000 nm (0.62-0.89 eV) causes a reduction of the PL intensity, the magnitude of which scales linearly with IR power. Further, KF post deposition treatment has only a modest influence on the effect of the IR excitation. Initial data suggest that we have developed an optical characterization tool for band-gap defect states.

  15. Copper indium gallium (di)selenide: Electronic activities of grain boundaries and solar cell fabrication studies

    NASA Astrophysics Data System (ADS)

    Erkan, Mehmet Eray

    This dissertation is composed of three studies related to chalcopyrite solar cells. The first study is on electronic activities of grain boundaries (GBs) in CuInSe2 (CIS). Despite being polycrystalline, chalcopyrite thin film solar cells have reached record power conversion efficiencies. This is against the classical understanding on the effect of GBs in semiconductor materials. Because GBs are expected to be recombination centers and barriers against the carrier flow, reducing the device efficiency. Therefore, a complete understanding on the electronic behavior of chalcopyrite GBs is missing. Moreover, the high efficiency chalcopyrite solar cells are grown with Na impurities which positively affect the performance of the solar cell, so-called sodium effect. Research on chalcopyrite GBs has been coupled with the effect of Na impurities, because Na has been found segregated at the GBs. The study presented in this dissertation was performed on GBs in a Na-free CIS. It is important to study the GBs in a Na-free chalcopyrite to avoid any uncontrolled effects of Na segregation at the GBs, for instance a possible Na-related secondary phase formation which would affect the conclusions drawn on the natural behavior of chalcopyrite GBs. In addition, it is known that Sigma3 GBs in chalcopyrite solar cells are abundant; therefore, it is meaningful to investigate the differences between Sigma3 and non-Sigma3 GBs. For this purpose, Sigma3, close to Sigma3 and Sigma9 GBs in a Bridgman-grown multicrystalline Na-free CIS wafer were identified by electron backscatter diffraction and their electronic properties were investigated by Kelvin probe force microscope and cathodoluminescence in scanning electron microscope. It is shown that the Sigma3 GB is neutral and it does not behave as a recombination center, whereas once the geometry of a GB deviates from the Sigma3 geometry, such as close to Sigma3 and Sigma9 GBs, the GB becomes charged and behaves as a recombination center. This result was concluded to be due to the increase in the amount of defects at the GB that introduce midgap states as the Sigma value increases. Our results indicate that the surprising high performance seen in the polycrystalline chalcopyrite solar cells is possibly due to the abundance of electrically inactive Sigma3 GBs in this material. To investigate the effect of Na on CIS GBs, projected work includes the characterization of Sigma3 and non-Sigma3 GBs in CIS wafers grown with increasing Na concentration. Consequently, it will be possible to answer the following questions on the impact of sodium-effect on GBs: Is there a certain Na concentration for Na to affect the GB electrical properties and how does it affect both Sigma3 and non-Sigma3 GBs? In the second study, the use of selenoamide instead of direct use of H2Se for atmospheric pressure selenization reaction is proposed and its feasibility is shown by fabricating CIS solar cells with up to 1.6% power conversion efficiency. In addition, observed In and Ga segregation towards the bottom of the CIS and CIGS thin films, respectively, are investigated through phase transformations occurring during the selenization and systematically designed annealing processes. The third study is on the effect of flow type on the growth kinetics of CdS thin films deposited by chemical bath deposition. CdS thin films are deposited on glass substrates under turbulent and laminar flow conditions only by changing the substrate's alignment with respect to the bottom of the beaker in unstirred bath. It is shown that the flow condition of the bath does not change the optical and structural properties of CdS; however, deposition under laminar flow is explained to be diffusion-limited, whereas it is feed-limited under turbulent flow.

  16. Study of electrical properties of polycrystalline materials based on indium and copper selenides under high pressure

    NASA Astrophysics Data System (ADS)

    Melnikova, N. V.; Kurochka, K. V.; Zaikova, V. E.; Tebenkov, A. V.; Babushkin, A. N.

    2015-11-01

    This paper discusses the influence of high pressures (up to 50 GPa) on the electrical properties of the polycrystalline materials (InSe)x(CuAsSe2)1-x, x = 0.05 and 0.5. It was found that, for each compound, features in the pressure dependence of all the physical parameters of interest occur in the same pressure intervals, which can be due to structural transitions and a change in the electron structure.

  17. Design and Optimization of Copper Indium Gallium Selenide Solar Cells for Lightweight Battlefield Application

    DTIC Science & Technology

    2014-06-01

    those of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government. IRB Protocol number ____N...Matrix Flatpanel Displays and Devices, Kyoto , Japan, 2012, pp. 67–70. [23] R. Yang, Z. Bai, D. Wang, and D. Wang, “High efficient thin film CdTe solar

  18. Structure-fluctuation-induced abnormal thermoelectric properties in semiconductor copper selenide

    SciTech Connect

    Liu, Huili; Shi, Xun; Kirkham, Melanie J; Wang, Hsin; Li, Qiang; Uher, Ctirad; Zhang, Wenqing; Chen, Lidong

    2013-01-01

    Thermoelectric effects and related technologies have attracted a great interest due to the world-wide energy harvesting. Thermoelectricity has usually been considered in the context of stable material phases. Here we report that the fluctuation of structures during the second-order phase transition in Cu2Se semiconductor breaks the conventional trends of thermoelectric transports in normal phases, leading to a critically phase-transition-enhanced thermoelectric figure of merit zT above unity at 400K, a three times larger value than for the normal phases. Dynamic structural transformations introduce intensive fluctuations and extreme complexity, which enhance the carrier entropy and thus the thermopower, and strongly scatter carriers and phonons as well to make their transports behave critically.

  19. Formation of Two-Dimensional Copper Selenide on Cu(111) at Very Low Selenium Coverage.

    PubMed

    Walen, Holly; Liu, Da-Jiang; Oh, Junepyo; Yang, Hyun Jin; Kim, Yousoo; Thiel, Patricia A

    2016-07-18

    Using scanning tunneling microscopy (STM), we observed that adsorption of Se on Cu(111) produced islands with a (√3×√3)R30° structure at Se coverages far below the structure's ideal coverage of 1/3 monolayer. On the basis of density functional theory (DFT), these islands cannot form due to attractive interactions between chemisorbed Se atoms. DFT showed that incorporating Cu atoms into the √3-Se lattice stabilizes the structure, which provided a plausible explanation for the experimental observations. STM revealed three types of √3 textures. We assigned two of these as two-dimensional layers of strained CuSe, analogous to dense planes of bulk klockmannite (CuSe). Klockmannite has a bulk lattice constant that is 11 % shorter than √3 times the surface lattice constant of Cu(111). This offers a rationale for the differences observed between these textures, for which strain limits the island size or distorts the √3 lattice. STM showed that existing step edges adsorb Se and facet toward ⟨12‾ 1⟩, which is consistent with DFT.

  20. Interaction between crystal lattice and mobile ions in copper selenides studied by EXAFS spectroscopy

    NASA Astrophysics Data System (ADS)

    Asylgushina, G. N.; Bikkulova, N. N.; Titova, S. G.; Kochubey, D. I.

    2005-05-01

    Interaction between crystal lattice and mobile Cu ions has been studied in Cu 2-xSe in superionic and in normal state using EXAFS-spectroscopy. It has been found that the transition from normal to superionic state and change of mobile Cu ion concentration practically do not have an influence on local state of Cu atoms, but change of both these parameters is accompanied by a change of Se-sublattice state.

  1. Effect of dietary copper on selenium toxicity in Fischer 344 rats.

    PubMed

    Tatum, L; Shankar, P; Boylan, L M; Spallholz, J E

    2000-12-01

    The purpose of this study was to investigate the ameliorating effects of dietary copper supplementation on selenium toxicity. Nine groups (n = 6) of weanling Fischer 344 female rats were randomly assigned to treatment groups and fed diets containing nontoxic levels of copper as CuCl2 and/or selenium as selenite or selenocystamine. Weight gain, liver and spleen weights, plasma lipid peroxidation, and liver selenium and copper content were analyzed after the 6-wk treatment period. Concentrations of up to 10 times the daily lethal dose of dietary selenium were well tolerated in rats supplemented with dietary copper. As the dietary level of selenium was increased, the ratio of selenium to copper measured in the liver decreased. In the groups of rats in which dietary copper supplementation was absent and dietary selenium was supplemented, copper stores in the liver remained unchanged from control values. Copper's protective effects from dietary selenium toxicity may come from the formation of a copper-selenide complex that renders both selenium and copper metabolically unavailable and nontoxic.

  2. Dispersion strengthened copper

    DOEpatents

    Sheinberg, Haskell; Meek, Thomas T.; Blake, Rodger D.

    1990-01-01

    A composition of matter comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide, and a method for making this composition of matter.

  3. Dispersion strengthened copper

    DOEpatents

    Sheinberg, Haskell; Meek, Thomas T.; Blake, Rodger D.

    1989-01-01

    A composition of matter comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide, and a method for making this composition of matter.

  4. Enzymatic methylation of sulfide, selenide, and organic thiols by Tetrahymena thermophila

    SciTech Connect

    Drotar, A.; Fall, L.R.; Mishalanie, E.A.; Tavernier, J.E.; Fall, R.

    1987-09-01

    Cell extracts from the ciliate Tetrahymena thermophila catalyzed the S-adenosylmethionine-dependent methylation of sulfide. The product of the reaction, methanethiol, was detected by a radiometric assay and by a gas-chromatographic assay coupled to a sulfur-selective chemiluminescence detector. Extracts also catalyzed the methylation of selenide, and the product was shown by gas chromatography-mass spectrometry to be methaneselenol. The sulfide and selenide methyltransferase activities copurified with the aromatic thiol methyltransferase previously characterized from this organism, but heat inactivation experiments suggested the involvement of distinct sulfide and selenide methyltransferases. Short-term toxicity tests were carried out for sulfide, selenide, and their methylated derivatives; the monomethylated forms were somewhat more toxic than the nonmethylated or dimethylated compounds. Cell suspensions of T. thermophila exposed to sulfide, methanethiol, or their selenium analogs emitted methylated derivatives into the headspace. These results suggest that this freshwater protozoan is capable of the stepwise methylation of sulfide and selenide, leading to the release of volatile methylated sulfur or selenium gases.

  5. Amorphous Indium Selenide Thin Films Prepared by RF Sputtering: Thickness-Induced Characteristics.

    PubMed

    Han, Myoung Yoo; Park, Yong Seob; Kim, Nam-Hoon

    2016-05-01

    The influence of indium composition, controlled by changing the film thickness, on the optical and electrical properties of amorphous indium selenide thin films was studied for the application of these materials as Cd-free buffer layers in CI(G)S solar cells. Indium selenide thin films were prepared using RF magnetron sputtering method. The indium composition of the amorphous indium selenide thin films was varied from 94.56 to 49.72 at% by increasing the film thickness from 30 to 70 nm. With a decrease in film thickness, the optical transmittance increased from 87.63% to 96.03% and Eg decreased from 3.048 to 2.875 eV. Carrier concentration and resistivity showed excellent values of ≥1015 cm(-3) and ≤ 10(4) Ω x cm, respectively. The conductivity type of the amorphous indium selenide thin films could be controlled by changing the film-thickness-induced amount of In. These results indicate the possibility of tuning the properties of amorphous indium selenide thin films by changing their composition for use as an alternate buffer layer material in CI(G)S solar cells.

  6. Enzymatic methylation of sulfide, selenide, and organic thiols by Tetrahymena thermophila.

    PubMed Central

    Drotar, A; Fall, L R; Mishalanie, E A; Tavernier, J E; Fall, R

    1987-01-01

    Cell extracts from the ciliate Tetrahymena thermophila catalyzed the S-adenosylmethionine-dependent methylation of sulfide. The product of the reaction, methanethiol, was detected by a radiometric assay and by a gas-chromatographic assay coupled to a sulfur-selective chemiluminescence detector. Extracts also catalyzed the methylation of selenide, and the product was shown by gas chromatography-mass spectrometry to be methaneselenol. The sulfide and selenide methyltransferase activities copurified with the aromatic thiol methyltransferase previously characterized from this organism (A.-M. Drotar and R. Fall, Pestic. Biochem. Physiol. 25:396-406, 1986), but heat inactivation experiments suggested the involvement of distinct sulfide and selenide methyltransferases. Short-term toxicity tests were carried out for sulfide, selenide, and their methylated derivatives; the monomethylated forms were somewhat more toxic than the nonmethylated or dimethylated compounds. Cell suspensions of T. thermophila exposed to sulfide, methanethiol, or their selenium analogs emitted methylated derivatives into the headspace. These results suggest that this freshwater protozoan is capable of the stepwise methylation of sulfide and selenide, leading to the release of volatile methylated sulfur or selenium gases. PMID:3674871

  7. Copper Metallochaperones

    PubMed Central

    Robinson, Nigel J.; Winge, Dennis R.

    2014-01-01

    The current state of knowledge on how copper metallochaperones support the maturation of cuproproteins is reviewed. Copper is needed within mitochondria to supply the CuA and intramembrane CuB sites of cytochrome oxidase, within the trans-Golgi network to supply secreted cuproproteins and within the cytosol to supply superoxide dismutase 1 (Sod1). Subpopulations of copper-zinc superoxide dismutase also localize to mitochondria, the secretory system, the nucleus and, in plants, the chloroplast, which also requires copper for plastocyanin. Prokaryotic cuproproteins are found in the cell membrane and in the periplasm of gram-negative bacteria. Cu(I) and Cu(II) form tight complexes with organic molecules and drive redox chemistry, which unrestrained would be destructive. Copper metallochaperones assist copper in reaching vital destinations without inflicting damage or becoming trapped in adventitious binding sites. Copper ions are specifically released from copper metallochaperones upon contact with their cognate cuproproteins and metal transfer is thought to proceed by ligand substitution. PMID:20205585

  8. Electron-nuclear double resonance studies of point defects in silver gallium selenide and zinc germanium phosphide

    NASA Astrophysics Data System (ADS)

    Stevens, Kevin Taylor

    Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) studies have been performed on two chalcopyrite crystals grown by the horizontal-gradient-freeze technique. An impurity defect has been characterized in silver gallium selenide (AgGaSe2) and has been identified as a Ni+ ion substituting for a Ag+ ion. This nickel defect exists in as-grown crystals in the paramagnetic state. A complete ENDOR angular dependence study provided spin-Hamiltonian parameters for the 61Ni isotope as well as the neighboring selenium ions (77Se) and gallium ions (69Ga and 71Ga). Optical absorption data taken at room temperature and low temperature showed a broad band peaking near 2.2 microns. The zero-phonon line position was determined from the low temperature data. The EPR and optical absorption data were consistent with each other, suggesting the absorption band was associated with Ni+ impurities. Two point defects have been identified and characterized in zinc germanium phosphide (ZnGeP 2). The first is a copper impurity, which substitutes for a zinc ion in the ZnGeP2 lattice. The copper impurity acts as a conventional acceptor and is not paramagnetic in the as-grown condition, i.e., the light-off condition. Upon illumination of the sample with 633-nm or 1064-nm light, the copper acceptor gives up an electron and becomes paramagnetic. The EPR spectrum consists of resolved hyperfine due to the copper nucleus (63Cu and 65Cu) as well as neighboring phosphorous nuclei ( 31P). The spin-Hamiltonian parameters have been determined from ENDOR measurements of the light-induced EPR spectrum. The second defect that has been studied in ZnGeP2 is the previously identified zinc vacancy (VZn). EPR and ENDOR studies have previously characterized the g values and primary hyperfine interactions associated with the VZn. Further ENDOR measurements have been made in order to identify hyperfine interactions with more distant phosphorous neighbors. The results led to spin

  9. Thermoelectric characterization of individual bismuth selenide topological insulator nanoribbons

    NASA Astrophysics Data System (ADS)

    Tang, Hao; Wang, Xiaomeng; Xiong, Yucheng; Zhao, Yang; Zhang, Yin; Zhang, Yan; Yang, Juekuan; Xu, Dongyan

    2015-04-01

    Bismuth selenide (Bi2Se3) nanoribbons have attracted tremendous research interest recently to study the properties of topologically protected surface states that enable new opportunities to enhance the thermoelectric performance. However, the thermoelectric characterization of individual Bi2Se3 nanoribbons is rare due to the technological challenges in the measurements. One challenge is to ensure good contacts between the nanoribbon and electrodes in order to determine the thermal and electrical properties accurately. In this work, we report the thermoelectric characterization of individual Bi2Se3 nanoribbons via a suspended microdevice method. Through careful measurements, we have demonstrated that contact thermal resistance is negligible after the electron-beam-induced deposition (EBID) of platinum/carbon (Pt/C) composites at the contacts between the nanoribbon and electrodes. It is shown that the thermal conductivity of the Bi2Se3 nanoribbons is less than 50% of the bulk value over the whole measurement temperature range, which can be attributed to enhanced phonon boundary scattering. Our results indicate that intrinsic Bi2Se3 nanoribbons prepared in this work are highly doped n-type semiconductors, and therefore the Fermi level should be in the conduction band and no topological transport behavior can be observed in the intrinsic system.

  10. Methylation and demethylation of intermediates selenide and methylselenol in the metabolism of selenium.

    PubMed

    Ohta, Yuki; Suzuki, Kazuo T

    2008-01-15

    All nutritional selenium sources are transformed into the assumed common intermediate selenide for the syntheses of selenoproteins for utilization and/or of selenosugar for excretion. Methylselenol [monomethylselenide, MMSe] is the assumed intermediate leading to other methylated metabolites, dimethylselenide (DMSe) and trimethylselenonium (TMSe) for excretion, and also to the intermediate selenide from methylselenocysteine and methylseleninic acid (MSA). Here, related methylation and demethylation reactions were studied in vitro by providing chemically reactive starting substrates (76Se-selenide, 77Se-MMSe and 82Se-DMSe) which were prepared in situ by the reduction of the corresponding labeled proximate precursors (76Se-selenite, 77Se-MSA and 82Se-dimethylselenoxide (DMSeO), respectively) with glutathione, the three substrates being incubated simultaneously in rat organ supernatants and homogenates. The resulting chemically labile reaction products were detected simultaneously by speciation analysis with HPLC-ICP-MS after converting the products and un-reacted substrates to the corresponding oxidized derivatives (selenite, MSA and DMSeO). The time-related changes in selenium isotope profiles showed that demethylation of MMSe to selenide was efficient but that of DMSe to MMSe was negligible, whereas methylation of selenide to MMSe, and MMSe to DMSe were efficient, and that of DMSe to TMSe occurred less efficiently. The present methylation and demethylation reactions on equilibrium between selenide, MMSe and DMSe without producing selenosugar and selenoproteins indicated that DMSe rather than TMSe is produced as the end product, suggesting that DMSe is to be excreted more abundantly than TMSe. Organ-dependent differences in the methylation and demethylation reactions were characterized for the liver, kidney and lung.

  11. Methylation and demethylation of intermediates selenide and methylselenol in the metabolism of selenium

    SciTech Connect

    Ohta, Yuki; Suzuki, Kazuo T.

    2008-01-15

    All nutritional selenium sources are transformed into the assumed common intermediate selenide for the syntheses of selenoproteins for utilization and/or of selenosugar for excretion. Methylselenol [monomethylselenide, MMSe] is the assumed intermediate leading to other methylated metabolites, dimethylselenide (DMSe) and trimethylselenonium (TMSe) for excretion, and also to the intermediate selenide from methylselenocysteine and methylseleninic acid (MSA). Here, related methylation and demethylation reactions were studied in vitro by providing chemically reactive starting substrates ({sup 76}Se-selenide, {sup 77}Se-MMSe and {sup 82}Se-DMSe) which were prepared in situ by the reduction of the corresponding labeled proximate precursors ({sup 76}Se-selenite, {sup 77}Se-MSA and {sup 82}Se-dimethylselenoxide (DMSeO), respectively) with glutathione, the three substrates being incubated simultaneously in rat organ supernatants and homogenates. The resulting chemically labile reaction products were detected simultaneously by speciation analysis with HPLC-ICP-MS after converting the products and un-reacted substrates to the corresponding oxidized derivatives (selenite, MSA and DMSeO). The time-related changes in selenium isotope profiles showed that demethylation of MMSe to selenide was efficient but that of DMSe to MMSe was negligible, whereas methylation of selenide to MMSe, and MMSe to DMSe were efficient, and that of DMSe to TMSe occurred less efficiently. The present methylation and demethylation reactions on equilibrium between selenide, MMSe and DMSe without producing selenosugar and selenoproteins indicated that DMSe rather than TMSe is produced as the end product, suggesting that DMSe is to be excreted more abundantly than TMSe. Organ-dependent differences in the methylation and demethylation reactions were characterized for the liver, kidney and lung.

  12. Two-dimensional tin selenide nanostructures for flexible all-solid-state supercapacitors.

    PubMed

    Zhang, Chunli; Yin, Huanhuan; Han, Min; Dai, Zhihui; Pang, Huan; Zheng, Yulin; Lan, Ya-Qian; Bao, Jianchun; Zhu, Jianmin

    2014-04-22

    Due to their unique electronic and optoelectronic properties, tin selenide nanostructures show great promise for applications in energy storage and photovoltaic devices. Despite the great progress that has been achieved, the phase-controlled synthesis of two-dimensional (2D) tin selenide nanostructures remains a challenge, and their use in supercapacitors has not been explored. In this paper, 2D tin selenide nanostructures, including pure SnSe2 nanodisks (NDs), mixed-phase SnSe-SnSe2 NDs, and pure SnSe nanosheets (NSs), have been synthesized by reacting SnCl2 and trioctylphosphine (TOP)-Se with borane-tert-butylamine complex (BTBC) and 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone. Utilizing the interplay of TOP and BTBC and changing only the amount of BTBC, the phase-controlled synthesis of 2D tin selenide nanostructures is realized for the first time. Phase-dependent pseudocapacitive behavior is observed for the resulting 2D nanostructures. The specific capacitances of pure SnSe2 NDs (168 F g(-1)) and SnSe NSs (228 F g(-1)) are much higher than those of other reported materials (e.g., graphene-Mn3O4 nanorods and TiN mesoporous spheres); thus, these tin selenide materials were used to fabricate flexible, all-solid-state supercapacitors. Devices fabricated with these two tin selenide materials exhibited high areal capacitances, good cycling stabilities, excellent flexibilities, and desirable mechanical stabilities, which were comparable to or better than those reported recently for other solid-state devices based on graphene and 3D GeSe2 nanostructures. Additionally, the rate capability of the SnSe2 NDs device was much better than that of the SnSe NS device, indicating that SnSe2 NDs are promising active materials for use in high-performance, flexible, all-solid-state supercapacitors.

  13. The Parent Li(OH)FeSe Phase of Lithium Iron Hydroxide Selenide Superconductors.

    PubMed

    Woodruff, Daniel N; Schild, Francesca; Topping, Craig V; Cassidy, Simon J; Blandy, Jack N; Blundell, Stephen J; Thompson, Amber L; Clarke, Simon J

    2016-10-03

    Lithiation of hydrothermally synthesized Li1-xFex(OH)Fe1-ySe turns on high-temperature superconductivity when iron ions are displaced from the hydroxide layers by reductive lithiation to fill the vacancies in the iron selenide layers. Further lithiation results in reductive iron extrusion from the hydroxide layers, which turns off superconductivity again as the stoichiometric composition Li(OH)FeSe is approached. The results demonstrate the twin requirements of stoichiometric FeSe layers and reduction of Fe below the +2 oxidation state as found in several iron selenide superconductors.

  14. Selenide-Catalyzed Stereoselective Construction of Tetrasubstituted Trifluoromethylthiolated Alkenes with Alkynes.

    PubMed

    Wu, Jin-Ji; Xu, Jia; Zhao, Xiaodan

    2016-10-17

    The efficient regio- and stereoselective construction of tetrasubstituted alkenes is challenging and very important. For this purpose, we have developed an efficient approach to synthesize tetrasubstituted trifluoromethylthiolated alkenes from simple alkynes in excellent regio- and stereoselectivities by selenide-catalyzed multicomponent coupling. Using this method, trifluoromethylthiolated alkenyl triflates and arenes were achieved. In particular, the triflates could be further converted into carbofunctionalized alkenes by palladium-catalyzed cross-coupling reactions. Our method provides a new pathway for the construction of trifluoromethylthiolated tricarboalkenes. This work presents the first example of selenide-catalyzed trifluoromethylthiolation of alkynes and enables the challenging functionalizations of alkynes.

  15. Metal Selenides as Efficient Counter Electrodes for Dye-Sensitized Solar Cells.

    PubMed

    Jin, Zhitong; Zhang, Meirong; Wang, Min; Feng, Chuanqi; Wang, Zhong-Sheng

    2017-03-10

    Solar energy is the most abundant renewable energy available to the earth and can meet the energy needs of humankind, but efficient conversion of solar energy to electricity is an urgent issue of scientific research. As the third-generation photovoltaic technology, dye-sensitized solar cells (DSSCs) have gained great attention since the landmark efficiency of ∼7% reported by O'Regan and Grätzel. The most attractive features of DSSCs include low cost, simple manufacturing processes, medium-purity materials, and theoretically high power conversion efficiencies. As one of the key materials in DSSCs, the counter electrode (CE) plays a crucial role in completing the electric circuit by catalyzing the reduction of the oxidized state to the reduced state for a redox couple (e.g., I3(-)/I(-)) in the electrolyte at the CE-electrolyte interface. To lower the cost caused by the typically used Pt CE, which restricts the large-scale application because of its low reserves and high price, great effort has been made to develop new CE materials alternative to Pt. A lot of Pt-free electrocatalysts, such as carbon materials, inorganic compounds, conductive polymers, and their composites with good electrocatalytic activity, have been applied as CEs in DSSCs in the past years. Metal selenides have been widely used as electrocatalysts for the oxygen reduction reaction and light-harvesting materials for solar cells. Our group first expanded their applications to the DSSC field by using in situ-grown Co0.85Se nanosheet and Ni0.85Se nanoparticle films as CEs. This finding has inspired extensive studies on developing new metal selenides in order to seek more efficient CE materials for low-cost DSSCs, and a lot of meaningful results have been achieved in the past years. In this Account, we summarize recent advances in binary and mutinary metal selenides applied as CEs in DSSCs. The synthetic methods for metal selenides with various morphologies and stoichiometric ratios and deposition

  16. Solid-gas phase equilibria and thermodynamic properties of cadmium selenide.

    NASA Technical Reports Server (NTRS)

    Sigai, A. G.; Wiedemeier, H.

    1972-01-01

    Accurate vapor pressures are determined through direct weight loss measurements using the Knudsen effusion technique. The experimental data are evaluated by establishing the mode of vaporization and determining the heat capacity of cadmium selenide at elevated temperatures. Additional information is obtained through a second- and third-law evaluation of data, namely, the heat of formation and the absolute entropy of cadmium selenide. A preferential loss of selenium during the initial heating of CdSe is observed, which leads to a deviation in stoichiometry.

  17. Living bio-membrane bi-template route for simultaneous synthesis of lead selenide nanorods and nanotubes

    NASA Astrophysics Data System (ADS)

    Li, Li; Wu, Qing-Sheng; Ding, Ya-Ping

    2004-12-01

    In this paper, a novel method is reported by which semiconductor materials are synthesized via controlled organism membranes. Semiconductor lead selenide nanorods and nanotubes have been successfully prepared simultaneously through living bio-membrane bi-templates of the mungbean sprout. The lead selenide nanorods are approximately 45 nm in diameter, and up to 1100 nm in length; all of them are single crystalline in structure. Lead selenide nanotubes are 50 nm in diameter, and up to 2000 nm in length, and are poly-crystalline in structure. The characteristics of the products are illustrated by various means, and their possible formation mechanism is explored.

  18. Benzyltrifluoromethyl (or Fluoroalkyl) Selenide: Reagent for Electrophilic Trifluoromethyl (or Fluoroalkyl) Selenolation.

    PubMed

    Glenadel, Quentin; Ismalaj, Ermal; Billard, Thierry

    2016-09-16

    Trifluoromethylseleno substituent (CF3Se) is an emerging group, but its direct introduction onto organic molecules is still quite limited and mainly restricted to nucleophilic methods. Herein, we describe a new approach to easily and safely perform electrophilic trifluoromethylselenolation starting from a simple and easily accessible reagent, namely, benzyltrifluoromethyl selenide. This strategy can be generalized to various fluoroalkylselanyl groups, even functionalized ones.

  19. Photovoltaic properties of cadmium selenide-titanyl phthalocyanine planar heterojunction devices

    NASA Astrophysics Data System (ADS)

    Szostak, J.; Jarosz, G.; Signerski, R.

    2015-07-01

    Photovoltaic phenomenon taking place in cadmium selenide (CdSe)/titanyl phthalocyanine (TiOPc) planar heterojunction devices is described. Mechanisms of free charge carrier generation and their recombination in the dark and under illumination are analyzed, chosen photovoltaic parameters are presented.

  20. Apoptosis induced by cadmium selenide quantum dots in JB6 cells.

    PubMed

    Kong, Lu; Zhang, Ting; Tang, Meng; Pu, Yuepu

    2012-11-01

    Quantum dots are being widely used in physics and in the biomedical industry in recent years due to their excellent optical characteristics. However, studies have shown that cadmium selenide core-shell quantum dots exhibit cytotoxicity. The present study investigates the induction of apoptosis and the signal pathways involved in this process by cadmium selenide-core quantum dots in JB6 cells. We found that cadmium selenide-core quantum dots exhibited high cytotoxicity and caused apoptosis and necrosis of JB6 cells. Cell cycle detection showed an increase in the percentage of G1 phase cells but a decrease in the percentage of S and G2 phase cells after JB6 cells treated with various concentrations of cadmium selenide core-shell quantum dots for 24 h. At the same time, western-blot analysis showed an activation of pro-apoptotic factors including FAS, BAX and BID. Apoptosis-inducing factor (AIF), full length and cleaved caspase-6 and -8 were up-regulated. The current study provides a guide for the safe use of QDs as a new kind of biological fluorescence material for biological and medical applications.

  1. Preparation of cadmium selenide colloidal quantum dots in non-coordinating solvent octadecene

    NASA Astrophysics Data System (ADS)

    Mazing, D. S.; Brovko, A. M.; Matyushkin, L. B.; Aleksandrova, O. A.; Moshnikov, V. A.

    2015-12-01

    Nearly monodisperse cadmium selenide quantum dots (QDs) were synthesized in non-coordinating solvent octadecene through phosphine-free method using oleic acid as surfactant. Selenium powder suspension in octadecene obtained by ultrasound processing was used as one of precursor solutions. Influence of multiple selenium precursor injections on nanocrystal growth process was investigated. Nanoparticles were characterized by means of absorption and photoluminescence spectroscopies.

  2. Draft Genome Sequence of Pseudomonas aeruginosa Strain RB, a Bacterium Capable of Synthesizing Cadmium Selenide Nanoparticles.

    PubMed

    Ayano, Hiroyuki; Kuroda, Masashi; Soda, Satoshi; Ike, Michihiko

    2014-05-15

    Pseudomonas aeruginosa strain RB is a bacterium capable of synthesizing cadmium selenide (CdSe) nanoparticles and was isolated from a soil sample. Here, we present the draft genome sequence of P. aeruginosa strain RB. To the best of our knowledge, this is the first report of a draft genome of a CdSe-synthesizing bacterium.

  3. Synthesis and optical properties of cadmium selenide quantum dots for white light-emitting diode application

    SciTech Connect

    Xu, Xianmei; Wang, Yilin; Gule, Teri; Luo, Qiang; Zhou, Liya; Gong, Fuzhong

    2013-03-15

    Highlights: ► Stable CdSe QDs were synthesized by the one-step and two-level process respectively. ► The fabricated white LEDs show good white balance. ► CdSe QDs present well green to yellow band luminescence. ► CdSe QDs displayed a broad excitation band. - Abstract: Yellow light-emitting cadmium selenide quantum dots were synthesized using one-step and two-step methods in an aqueous medium. The structural luminescent properties of these quantum dots were investigated. The obtained cadmium selenide quantum dots displayed a broad excitation band suitable for blue or near-ultraviolet light-emitting diode applications. White light-emitting diodes were fabricated by coating the cadmium selenide samples onto a 460 nm-emitting indium gallium nitrite chip. Both samples exhibited good white balance. Under a 20 mA working current, the white light-emitting diode fabricated via the one-step and two-step methods showed Commission Internationale de l’Éclairage coordinates at (0.27, 0.23) and (0.27, 0.33), respectively, and a color rendering index equal to 41 and 37, respectively. The one-step approach was simpler, greener, and more effective than the two-step approach. The one-step approach can be enhanced by combining cadmium selenide quantum dots with proper phosphors.

  4. Copper-mercury film electrode for cathodic stripping voltammetric determination of Se(IV).

    PubMed

    Sladkov, Vladimir; David, François; Fourest, Blandine

    2003-01-01

    The copper-mercury film electrode has been suggested for the determination of Se(IV) in a wide range of concentration from 1x10(-9) to 1x10(-6) mol L(-1)by square-wave cathodic stripping voltammetry. Insufficient reproducibility and sensitivity of the mercury film electrode have been overcome by using copper(II) ions during the plating procedure. Copper(II) has been found to be reduced and form a reproducible copper-mercury film on a glassy carbon electrode surface. The plating potential and time, the concentration of copper(II) and the concentration of the supporting electrolyte have been optimised. Microscopy has been used for a study of the morphology of the copper-mercury film. It has been found that it is the same as for the mercury one. The preconcentration step consists in electrodeposition of copper selenide on the copper-mercury film. The relative standard deviation is 4.3% for 1x10(-6) mol L(-1) of Se(IV). The limit of detection is 8x10(-10) mol L(-1) for 5 min of accumulation.

  5. Photoluminescence Studies of Silver-Exchanged Cadmium Selenide Crystals. Modification of a Chemical Sensor for Aniline Derivatives by Heterojunction Formation

    DTIC Science & Technology

    1991-05-20

    Photoluminescence Studies of Silver-Exchanged Cadmium Selenide Crystals. Modification of a Chemical Sensor for Aniline Derivatives by Heterojunction...I__I 413r005 1 7TT..E (include Security Classification,) Photoluminescence Studies of Silver-Exchanged Cadmium Selenide Crystals. Moifification of a...Physical Chemistry 7 CO)SA7! CODES !8 S8.BECT TERMS Continue on reverse it. necessary and identity oy block nu’noer) Z.ELD CROUP SuB-GROUP cadmium

  6. An amphiphilic selenide catalyst behaves like a hybrid mimic of protein disulfide isomerase and glutathione peroxidase 7.

    PubMed

    Arai, Kenta; Moriai, Kenji; Ogawa, Akinobu; Iwaoka, Michio

    2014-12-01

    Protein disulfide isomerase (PDI) and glutathione peroxidase 7 (GPx7) cooperatively promote the oxidative folding of disulfide (SS)-containing proteins in endoplasmic reticulum by recognizing the nascent proteins to convert them into the native folds by means of SS formation and SS isomerization and by catalyzing reoxidation of reduced PDI with H2O2, respectively. In this study, new amphiphilic selenides with a long-chain alkyl group were designed as hybrid mimics of PDI and GPx7 and were applied to the refolding of reduced hen egg-white lysozyme (HEL-R). Competitive SS formation at pH 4 using HEL-R and glutathione (GSH) in the presence of the selenide catalyst and H2O2 showed that the amphiphilic selenides can preferentially catalyze SS formation of HEL-R, probably on account of hydrophobic interactions between the protein and the catalyst. In contrast, simple water-soluble selenides did not exhibit such behavior. In addition, when the pH of the solution was adjusted to 8.5 after the SS formation, surviving GSH promoted the SS isomerization of misfolded HEL to recover the native SS linkages. Thus, the amphiphilic selenides designed here could mimic the function of the PDI-GPx7 system. The combination of a water-soluble selenide and a long-chain alkyl group would be a useful motif in designing medicines for both protein misfolding diseases and antioxidant therapy.

  7. Copper cyanide

    Integrated Risk Information System (IRIS)

    Copper cyanide ; CASRN 544 - 92 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  8. Spinal mechanisms of antinociceptive effect caused by oral administration of bis-selenide in mice.

    PubMed

    Jesse, Cristiano R; Savegnago, Lucielli; Nogueira, Cristina W

    2008-09-22

    The present study was designed to investigate further the mechanisms involved in the antinociception caused by bis-selenide in behavioral model of pain in mice. Bis-selenide (5-50 mg/kg), given orally, produced significant inhibition of the antinociceptive behavior induced by intrathecal (i.t.) injection of glutamate (175 nmol/site), kainate (110 pmol/site) and (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD; 50 nmol/site) and the maximal inhibitions observed were 57+/-5, 46+/-7 and 73+/-3%, respectively. Bis-selenide failed to affect the nociception induced by alpha-amino-3-hydroxy-5-mehtyl-4-isoxazolepropionic acid (AMPA; 135 pmol/site) and N-methyl-d-aspartate (NMDA; 450 pmol/site). This compound also reduced the nociceptive response induced by tumor necrosis factor-alpha (TNF-alpha; 0.1 pg/site), interleukin-1beta (IL-1beta; 1 pg/site), substance P (SP) (135 ng/site, i.t.) and capsaicin (30 ng/site) and the inhibitions observed were 81+/-3%, 88+/-1%, 77+/-3 and 67+/-3, respectively. The oral administration of bis-selenide (25-50 mg/kg) in mice caused a significant increase in the reaction time to thermal stimuli in the hot plate test and the mean ID(50) value (and the 95% confidence limits) was 20.37 (15.00-25.74) mg/kg. The antinociceptive effect caused by bis-selenide (50 mg/kg, p.o.) on the hot plate test in mice was reversed by intrathecal (i.t.) injection of some K(+) channel blockers such as tetraethylammonium (TEA, non-selective voltage-dependent K(+) channel inhibitor) and glibenclamide (ATP-sensitive K(+) channel inhibitor), but not apamin and charybdotoxin (large- and small-conductance Ca(2+)-activated K(+) channel inhibitors, respectively). Together, these results indicate that bis-selenide produces antinociception at spinal sites through the activation of ATP-sensitive and voltage-gated K(+) channels and interaction with kainate and trans-ACDP receptors as well as vanilloid and neuropeptide receptors and pro-inflammatory cytokines.

  9. Magnesium-induced copper-catalyzed synthesis of unsymmetrical diaryl chalcogenide compounds from aryl iodide via cleavage of the Se-Se or S-S bond.

    PubMed

    Taniguchi, Nobukazu; Onami, Tetsuo

    2004-02-06

    The methodology for a copper-catalyzed preparation of diaryl chalcogenide compounds from aryl iodides and diphenyl dichalcogenide molecules is reported. Unsymmetrical diaryl sulfide or diaryl selenide can be synthesized from aryl iodide and PhYYPh (Y = S, Se) with a copper catalyst (CuI or Cu(2)O) and magnesium metal in one pot. This reaction can be carried out under neutral conditions according to an addition of magnesium metal as the reductive reagent. Furthermore, it is efficiently available for two monophenylchalcogenide groups generated from diphenyl dichalcogenide.

  10. Dispersion strengthened copper

    DOEpatents

    Sheinberg, H.; Meek, T.T.; Blake, R.D.

    1990-01-09

    A composition of matter is described which is comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide. A method for making this composition of matter is also described. This invention relates to the art of powder metallurgy and, more particularly, it relates to dispersion strengthened metals.

  11. Shape-controlled colloidal synthesis of rock-salt lead selenide nanocrystals.

    PubMed

    Jawaid, Ali M; Asunskis, Daniel J; Snee, Preston T

    2011-08-23

    Developing simple synthetic methods to control the size and morphology of nanocrystals is an active area of research as these parameters control the material's electronic and optical properties. For a semiconductor with a symmetrical crystal structure such as lead selenide, anisotropic colloidal growth has been previously accomplished via the use of templates, seeds, or by block assembly of smaller, symmetrical subunits. Here, we present a simple method to create monodisperse lead selenide nanorods and multipods at low temperatures. The size distribution and the observed morphologies are consistent with a continuous, anisotropic growth of material. The syntheses of these anisotropic shapes are due to the nature of the nuclei that form upon injection of precursors into partially oxidized alkene solvents that may contain lactone and carbonate-functional derivatives.

  12. Preparation and antibacterial activity studies of degraded polysaccharide selenide from Enteromorpha prolifera.

    PubMed

    Lü, Haitao; Gao, Yujie; Shan, Hu; Lin, Yingting

    2014-07-17

    Polysaccharide extracted from Enteromorpha prolifera possessed excellent biological activities, but its molecular weight was greatly high which influenced the activity. Organic Se had higher biological activities and was safer than inorganic Se species. In the present study, degraded polysaccharide selenide (Se-LEP) was synthesized from sodium selenite and degraded polysaccharide (LEP) with the catalysis of nitric acid. The preparation conditions of LEP and Se-LEP were optimized by orthogonal experiments. The selenite ester group was formed, and the selenium content was 1335.27 µg/g. The thermal stability of Se-LEP decreased. LEP had less inhibitory effects on bacteria and plant pathogenic fungi. Se-LEP had stronger inhibitory effect on Eschetichia coli, and weaker inhibitory effect on Staphylococcus aureus than polysaccharide selenide (Se-EP). Se-LEP also had better inhibitory effects on plant pathogenic fungi.

  13. Functional metal sulfides and selenides for the removal of hazardous dyes from Water.

    PubMed

    Shamraiz, Umair; Hussain, Raja Azadar; Badshah, Amin; Raza, Bareera; Saba, Sonia

    2016-06-01

    Water contamination by organic dyes, is among the most alarming threats to healthy green environment. Complete removal of organic dyes is necessary to make water healthy for drinking, cooking, and for other useful aspects. Recently use of nanotechnology for removing organic dyes, became fruitful because of high surface to volume ratio and adsorption properties. Among these materials, metal chalcogenides emerge as new class of active materials for water purification. In this review article, we gathered information related to sulfide and selenide based nanomaterials which include metal sulfides and selenides, their binary composites, and use of different capping agents and dopants for enhancing photocatalysis. We have discussed in detail, about adsorption power of different dyes, relative percentage degradation, reaction time and concentration.

  14. Effects of chemical and mechanical treatments on cadmium selenide single-crystal surface properties

    SciTech Connect

    Komisarchik, M.Sh.; Novosel'tseva, T.D.; Rumyantseva, T.Ya.; Lapushkina, L.V.; Orlov, Yu.F.

    1988-04-01

    The authors have examined the damaged layers on cadmium selenide single crystals after chemical polishing in alcoholic bromine solutions. The crystals were grown by directional crystallization and were cut on (0001) planes or had (01/anti/10) cleavage surfaces. Dynamic chemical polishing was used with 3 vol % bromine in ethanol with a constant stirring rate at room temperature. The surface composition was determined by x-ray photoelectron spectroscopy. Ellipsometry was used to estimate the oxide film thicknesses after various treatments. They examined the surface resistance as affected by the treatment, where electrodes made of eutectic indium-gallium alloy were used with a probe method. The dark surface resistance is dependent on the treatment. Chemical polishing with alcoholic bromine produced a damaged layer in cadmium selenide which differs from that after mechanical treatment.

  15. Peculiarities of thermal extinction of deep-center luminescence in cadmium selenide

    SciTech Connect

    Ermolovich, I.B.; Bulakh, B.M.

    1986-10-01

    The authors study the mechanisms of thermal extinction of the luminescence bands in cadmium selenide with lambda mad = 0.92 (band I) and 1.16 um (band II), for which the main photoluminescence centers are responsible. CdSe crystals grown from the gas phase and deliberately not doped were studied. The curves of the intensities of the bands I and II in the layers and single crystals are shown. A model is presented of the configurational coordinates for explaining the internal mechanism of extinction of impurity luminescence in crystal phosphors. A diagram is shown of the recombination transitions for wide-gap crystal phosphors with the anticipation of two luminescence centers and a nonradiative recombination center. This study proves that the corresponding luminescence centers in cadmium selenide single crystals and layers have the same physicochemical structure.

  16. Copper peroxide

    NASA Technical Reports Server (NTRS)

    Moser, L.

    1988-01-01

    A number of oxidizing agents, including chlorine, bromine, ozone and other peroxides, were allowed to act on copper solutions with the intention of forming copper peroxide. The only successful agent appears to be hydrogen peroxide. It must be used in a neutral 50 to 30 percent solution at a temperature near zero. Other methods described in the literature apparently do not work. The excess of hydrogen must be quickly sucked out of the brown precipitate, which it is best to wash with alcohol and ether. The product, crystalline under a microscope, can be analyzed only approximately. It approaches the formula CuO2H2O. In alkaline solution it appears to act catalytically in causing the decomposition of other peroxides, so that Na2O2 cannot be used to prepare it. On the addition of acids the H2O2 is regenerated. The dry substance decomposes much more slowly than the moist but is not very stable.

  17. Spectral properties of powder preparations of cadmium telluride and cadmium selenide with controlled nonstoichiometry

    NASA Astrophysics Data System (ADS)

    Khomyakov, A. V.; Mozhevitina, E. N.; Kuz'min, V. V.; Kon'kova, N. A.; Avetissov, I. Ch.

    2015-03-01

    The reflection spectra of powder preparations of cadmium telluride and cadmium selenide with different contents of overstoichiometric components have been investigated in the range of 800-1700 nm. The reflectance is found to be maximum for samples with compositions close to stoichiometric. An increase in the concentration of overstoichiometric cadmium more radically reduces the reflectance in comparison with preparations containing excess chalcogen. It is shown that halftone images in the near-IR range can be formed by using of these materials.

  18. Chemically deposited thin films of sulfides and selenides of antimony and bismuth as solar energy materials

    NASA Astrophysics Data System (ADS)

    Nair, M. T.; Nair, Padmanabhan K.; Garcia, V. M.; Pena, Y.; Arenas, O. L.; Garcia, J. C.; Gomez-Daza, O.

    1997-10-01

    Chemical bath deposition techniques for bismuth sulfide, bismuth selenide, antimony sulfide, and antimony selenide thin films of about 0.20 - 0.25 micrometer thickness are reported. All these materials may be considered as solar absorber films: strong optical absorption edges, with absorption coefficient, (alpha) , greater than 104 cm-1, are located at 1.31 eV for Bi2Se3, 1.33 eV for Bi2S3, 1.8 eV for Sb2S3, and 1.35 eV for Sb2Se3. As deposited, all the films are nearly amorphous. However, well defined crystalline peaks matching bismuthinite (JCPDS 17- 0320), paraguanajuatite (JCPDS 33-0214), and stibnite (JCPDS 6-0474) and antimony selenide (JCPDS 15-0861) for Bi2S3, Bi2Se3, Sb2S3 and Sb2Se3 respectively, are observed when the films are annealed in nitrogen at 300 degrees Celsius. This is accompanied by a substantial modification of the electrical conductivity in the films: from 10-7 (Omega) -1 cm-1 (in as prepared films) to 10 (Omega) -1 cm-1 in the case of bismuth sulfide and selenide films, and enhancement of photosensitivity in the case of antimony sulfide films. The chemical deposition of a CuS/CuxSe film on these Vx- VIy films and subsequent annealing at 300 degrees Celsius for 1 h at 1 torr of nitrogen leads to the formation of p-type films (conductivity of 1 - 100 (Omega) -1 cm-1) of multinary composition. Among these, the formation of Cu3BiS3 (JCPDS 9-0488) and Cu3SbS4 (JCPDS 35- 0581), CuSbS2 (JCPDS 35-0413) have been clearly detected. Solar energy applications of these films are suggested.

  19. Effect of sulfur doping on thermoelectric properties of tin selenide – A first principles study

    SciTech Connect

    Jayaraman, Aditya; Molli, Muralikrishna Kamisetti, Venkataramaniah

    2015-06-24

    In this work we present the thermoelectric properties of tin selenide (SnSe) and sulfur doped tin selenide(SnSe{sub (1-x)}S{sub x}, x= 0.125 and 0.25) obtained using first principles calculations. We investigated the electronic band structure using the FP-LAPW method within the sphere of the density functional theory. Thermoelectric properties were calculated using BOLTZTRAP code using the constant relaxation time approximation at three different temperatures 300, 600 and 800 K. Seebeck coefficient (S) was found to decrease with increasing temperature, electrical conductivity (σ/τ) was almost constant in the entire temperature range and thermal conductivity (κ/τ) increased with increasing temperature for all samples. Sulfur doped samples showed enhanced seebeck coefficient, decreased thermal conductivity and decreased electrical conductivity at all temperatures. At 300 K, S increased from 1500 µV/K(SnSe) to 1720μV/K(SnSe{sub 0.75}S{sub 0.25}), thermal conductivity decreased from 5 × 10{sup 15} W/mKs(SnSe) to 3 × 10{sup 15} W/mKs(SnSe{sub 0.75}S{sub 0.25}), electrical conductivity decreased from 7 × 10{sup 20}/Ωms(SnSe) to 5 × 10{sup 20} /Ωms(SnSe{sub 0.75}S{sub 0.25}). These calculations show that sulfur doped tin selenide exhibit better thermoelectric properties than undoped tin selenide.

  20. Contrasting role of antimony and bismuth dopants on the thermoelectric performance of lead selenide.

    PubMed

    Lee, Yeseul; Lo, Shih-Han; Chen, Changqiang; Sun, Hui; Chung, Duck-Young; Chasapis, Thomas C; Uher, Ctirad; Dravid, Vinayak P; Kanatzidis, Mercouri G

    2014-05-02

    Increasing the conversion efficiency of thermoelectric materials is a key scientific driver behind a worldwide effort to enable heat to electricity power generation at competitive cost. Here we report an increased performance for antimony-doped lead selenide with a thermoelectric figure of merit of ~1.5 at 800 K. This is in sharp contrast to bismuth doped lead selenide, which reaches a figure of merit of <1. Substituting antimony or bismuth for lead achieves maximum power factors between ~23-27 μW cm(-1) K(-2) at temperatures above 400 K. The addition of small amounts (~0.25 mol%) of antimony generates extensive nanoscale precipitates, whereas comparable amounts of bismuth results in very few or no precipitates. The antimony-rich precipitates are endotaxial in lead selenide, and appear remarkably effective in reducing the lattice thermal conductivity. The corresponding bismuth-containing samples exhibit smaller reduction in lattice thermal conductivity.

  1. Determination of dimethyl selenide and dimethyl sulphide compounds causing off-flavours in bottled mineral waters.

    PubMed

    Guadayol, Marta; Cortina, Montserrat; Guadayol, Josep M; Caixach, Josep

    2016-04-01

    Sales of bottled drinking water have shown a large growth during the last two decades due to the general belief that this kind of water is healthier, its flavour is better and its consumption risk is lower than that of tap water. Due to the previous points, consumers are more demanding with bottled mineral water, especially when dealing with its organoleptic properties, like taste and odour. This work studies the compounds that can generate obnoxious smells, and that consumers have described like swampy, rotten eggs, sulphurous, cooked vegetable or cabbage. Closed loop stripping analysis (CLSA) has been used as a pre-concentration method for the analysis of off-flavour compounds in water followed by identification and quantification by means of GC-MS. Several bottled water with the aforementioned smells showed the presence of volatile dimethyl selenides and dimethyl sulphides, whose concentrations ranged, respectively, from 4 to 20 ng/L and from 1 to 63 ng/L. The low odour threshold concentrations (OTCs) of both organic selenide and sulphide derivatives prove that several objectionable odours in bottled waters arise from them. Microbial loads inherent to water sources, along with some critical conditions in water processing, could contribute to the formation of these compounds. There are few studies about volatile organic compounds in bottled drinking water and, at the best of our knowledge, this is the first study reporting the presence of dimethyl selenides and dimethyl sulphides causing odour problems in bottled waters.

  2. COPPER CORROSION RESEARCH UPDATE

    EPA Science Inventory

    Copper release and corrosion related issues continue to be important to many water systems. The objective of this presentation is to discuss the current state of copper research at the USEPA. Specifically, the role of aging on copper release, use of phosphates for copper corrosio...

  3. Copper and copper proteins in Parkinson's disease.

    PubMed

    Montes, Sergio; Rivera-Mancia, Susana; Diaz-Ruiz, Araceli; Tristan-Lopez, Luis; Rios, Camilo

    2014-01-01

    Copper is a transition metal that has been linked to pathological and beneficial effects in neurodegenerative diseases. In Parkinson's disease, free copper is related to increased oxidative stress, alpha-synuclein oligomerization, and Lewy body formation. Decreased copper along with increased iron has been found in substantia nigra and caudate nucleus of Parkinson's disease patients. Copper influences iron content in the brain through ferroxidase ceruloplasmin activity; therefore decreased protein-bound copper in brain may enhance iron accumulation and the associated oxidative stress. The function of other copper-binding proteins such as Cu/Zn-SOD and metallothioneins is also beneficial to prevent neurodegeneration. Copper may regulate neurotransmission since it is released after neuronal stimulus and the metal is able to modulate the function of NMDA and GABA A receptors. Some of the proteins involved in copper transport are the transporters CTR1, ATP7A, and ATP7B and the chaperone ATOX1. There is limited information about the role of those biomolecules in the pathophysiology of Parkinson's disease; for instance, it is known that CTR1 is decreased in substantia nigra pars compacta in Parkinson's disease and that a mutation in ATP7B could be associated with Parkinson's disease. Regarding copper-related therapies, copper supplementation can represent a plausible alternative, while copper chelation may even aggravate the pathology.

  4. Copper and Copper Proteins in Parkinson's Disease

    PubMed Central

    Rivera-Mancia, Susana; Diaz-Ruiz, Araceli; Tristan-Lopez, Luis; Rios, Camilo

    2014-01-01

    Copper is a transition metal that has been linked to pathological and beneficial effects in neurodegenerative diseases. In Parkinson's disease, free copper is related to increased oxidative stress, alpha-synuclein oligomerization, and Lewy body formation. Decreased copper along with increased iron has been found in substantia nigra and caudate nucleus of Parkinson's disease patients. Copper influences iron content in the brain through ferroxidase ceruloplasmin activity; therefore decreased protein-bound copper in brain may enhance iron accumulation and the associated oxidative stress. The function of other copper-binding proteins such as Cu/Zn-SOD and metallothioneins is also beneficial to prevent neurodegeneration. Copper may regulate neurotransmission since it is released after neuronal stimulus and the metal is able to modulate the function of NMDA and GABA A receptors. Some of the proteins involved in copper transport are the transporters CTR1, ATP7A, and ATP7B and the chaperone ATOX1. There is limited information about the role of those biomolecules in the pathophysiology of Parkinson's disease; for instance, it is known that CTR1 is decreased in substantia nigra pars compacta in Parkinson's disease and that a mutation in ATP7B could be associated with Parkinson's disease. Regarding copper-related therapies, copper supplementation can represent a plausible alternative, while copper chelation may even aggravate the pathology. PMID:24672633

  5. [Effect of silver/zinc selenide core-shell structure spheres on the infrared absorption properties of sodium nitrate].

    PubMed

    Guo, Qiang; Li, Chun; Jia, Zhi-Jun; Yuan, Guang

    2013-10-01

    Silver/zinc selenide (Ag/ZnSe) core-shell structure spheres were made through the method of silver mirror reaction on zinc selenide micro spheres. Surface morphology of the spheres was depicted by scanning electron microscopy, X-ray diffraction and Fourier infrared absorption spectrum. This paper studies the effect of Ag/ZnSe core-shell structure spheres on the infrared absorption properties of sodium nitrate solution. The results show that, the anti-symmetric vibration absorption peaks of nitrate are blue-shifted, and the intensity are improved obviously by the effect of core-shell structure spheres.

  6. Solution-Liquid-Solid Synthesis of Hexagonal Nickel Selenide Nanowire Arrays with a Nonmetal Catalyst.

    PubMed

    Xu, Kun; Ding, Hui; Jia, Kaicheng; Lu, Xiuli; Chen, Pengzuo; Zhou, Tianpei; Cheng, Han; Liu, Si; Wu, Changzheng; Xie, Yi

    2016-01-26

    Inorganic nanowire arrays hold great promise for next-generation energy storage and conversion devices. Understanding the growth mechanism of nanowire arrays is of considerable interest for expanding the range of applications. Herein, we report the solution-liquid-solid (SLS) synthesis of hexagonal nickel selenide nanowires by using a nonmetal molecular crystal (selenium) as catalyst, which successfully brings SLS into the realm of conventional low-temperature solution synthesis. As a proof-of-concept application, the NiSe nanowire array was used as a catalyst for electrochemical water oxidation. This approach offers a new possibility to design arrays of inorganic nanowires.

  7. Power scaling of ultrafast laser inscribed waveguide lasers in chromium and iron doped zinc selenide.

    PubMed

    McDaniel, Sean A; Lancaster, Adam; Evans, Jonathan W; Kar, Ajoy K; Cook, Gary

    2016-02-22

    We report demonstration of Watt level waveguide lasers fabricated using Ultrafast Laser Inscription (ULI). The waveguides were fabricated in bulk chromium and iron doped zinc selenide crystals with a chirped pulse Yb fiber laser. The depressed cladding structure in Fe:ZnSe produced output powers of 1 W with a threshold of 50 mW and a slope efficiency of 58%, while a similar structure produced 5.1 W of output in Cr:ZnSe with a laser threshold of 350 mW and a slope efficiency of 41%. These results represent the current state-of-the-art for ULI waveguides in zinc based chalcogenides.

  8. Structure and physical properties of gallium selenide laser-intercalated with nickel

    NASA Astrophysics Data System (ADS)

    Pokladok, N. T.; Grygorchak, I. I.; Lukiyanets, B. A.; Popovich, D. I.

    2007-04-01

    Intercalated crystals of indium and gallium selenide are prepared. It is shown that laser intercalation of nickel into GaSe samples leads to a giant magnetoresistive effect whose magnitude and sign depend on the concentration of the guest component. The giant magnetoresistive effect in the InSe intercalation compounds is considerably weaker and does not exceed 5%. The experimental data obtained are explained in terms of magnetic delocalization (localization) of charge carriers with the participation of states of intercalated magnetically active atoms in the vicinity of the Fermi level.

  9. Scaling and spatial analysis of the dielectric response of cadmium selenide nanowires

    NASA Astrophysics Data System (ADS)

    Kanai, Yosuke; Cicero, Giancarlo

    2014-10-01

    Transverse dielectric response of hexagonal cadmium selenide (CdSe) nanowires was investigated using first-principles quantum mechanical calculations. Scaling behavior of polarizability was found to closely follow a simple dielectric cylinder model even for small nanowires with a diameter of a few nanometers. The spatial dependence of the dielectric response in the nanowires was analyzed in terms of maximally localized Wannier functions in order to elucidate the model behavior. Localized d electrons at cadmium atoms were found responsible for the simple analytic scaling of the polarizability, and the dielectric response in the center of nanowire was found converged to that of bulk already for 3 nm diameter nanowires.

  10. Zinc selenide-based large aperture photo-controlled deformable mirror.

    PubMed

    Quintavalla, Martino; Bonora, Stefano; Natali, Dario; Bianco, Andrea

    2016-06-01

    Realization of large aperture deformable mirrors with a large density of actuators is important in many applications, and photo-controlled deformable mirrors (PCDMs) represent an innovation. Herein we show that PCDMs are scalable realizing a 2-inch aperture device based on a polycrystalline zinc selenide (ZnSe) as the photoconductive substrate and a thin polymeric reflective membrane. ZnSe is electrically characterized and analyzed through a model that we previously introduced. The PCDM is then optically tested, demonstrating its capabilities in adaptive optics.

  11. TOPO-capped silver selenide nanoparticles and their incorporation into polymer nanofibers using electrospinning technique

    SciTech Connect

    More, D.S.; Moloto, M.J.; Moloto, N.; Matabola, K.P.

    2015-05-15

    Highlights: • Ag{sub 2}Se nanoparticles produced spherical particles with sizes 12 nm (180 °C) and 27 nm (200 °C). • Higher temperature produced increased particle size (∼75 nm) and changed in shape. • Ag{sub 2}Se nanoparticles (0.2–0.6%) added into PVP (35–45%) to yield reduced fiber beading. • Polymer nanofibers electrospun at 11–20 kV produced fiber diameters of 425–461 nm. • Optical properties in the fibers were observed due to the Ag{sub 2}Se nanoparticles loaded. - Abstract: Electrospinning is the most common technique for fabricating polymer fibers as well as nanoparticles embedded polymer fibers. Silver selenide nanoparticles were synthesized using tri-n-octylphosphine (TOP) as solvent and tri-n-octylphosphine oxide (TOPO) as capping environment. Silver selenide was prepared by reacting silver nitrate and selenium with tri-n-octylphosphine (TOP) to form TOP–Ag and TOP–Se solutions. Both absorption and emission spectra signify the formation of nanoparticles as well as the TEM which revealed spherical particles with an average particle size of 22 nm. The polymer, PVP used was prepared at concentrations ranging from (35 to 45 wt%) and the TOPO-capped silver selenide nanoparticles (0.2 and 0.6 wt%) were incorporated into them and electrospun by varying the voltage from 11 to 20 kV. The SEM images of the Ag{sub 2}Se/PVP composite fibers revealed the fibers of diameters with average values of 425 and 461 nm. The X-ray diffraction results show peaks which were identified due to α-Ag{sub 2}Se body centered cubic compound. The sharp peak observed for all the samples at 2θ = 44.5 suggest the presence of Ag in the face centered cubic which can be attributed to higher concentration of silver nitrate used with molar ratio of selenium to silver and the abundance of silver in the silver selenide crystal. Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and ultraviolet–visible spectroscopy were used to characterize the

  12. White-light emission from magic-sized cadmium selenide nanocrystals.

    PubMed

    Bowers, Michael J; McBride, James R; Rosenthal, Sandra J

    2005-11-09

    Magic-sized cadmium selenide (CdSe) nanocrystals have been pyrolytically synthesized. These ultra-small nanocrystals exhibit broadband emission (420-710 nm) that covers most of the visible spectrum while not suffering from self absorption. This behavior is a direct result of the extremely narrow size distribution and unusually large Stokes shift (40-50 nm). The intrinsic properties of these ultra-small nanocrystals make them an ideal material for applications in solid state lighting and also the perfect platform to study the molecule-to-nanocrystal transition.

  13. Transparent and flexible nonvolatile memory using poly(methylsilsesquioxane) dielectric embedded with cadmium selenide quantum dots

    NASA Astrophysics Data System (ADS)

    Ooi, Poh Choon; Li, Fushan; Perumal Veeramalai, Chandrasekar; Guo, Tailiang

    2014-12-01

    In this work, a transparent and flexible nonvolatile memory was fabricated using a solution process. The conduction mechanisms of the metal/insulator/metal structure consisting of cadmium selenide quantum dots embedded in poly(methylsilsesquioxane) dielectric layers were investigated in terms of current-voltage characteristics. The memory device is reprogrammable and stable up to 1 × 104 s with little deterioration and a distinct ON/OFF ratio of 104. Endurance cycle and retention tests of the as-fabricated memory device were also carried out. The results indicate that the device has good operating stability.

  14. Electrophoretic deposition of poly(3-decylthiophene) onto gold-mounted cadmium selenide nanorods.

    PubMed

    Garate, José-Antonio; English, Niall J; Singh, Ajay; Ryan, Kevin M; Mooney, Damian A; MacElroy, J M D

    2011-11-15

    Molecular mechanisms of electrophoretic deposition (EPD) of poly(3-decylthiophene) (P3DT) molecules onto vertically aligned cadmium selenide arrays have been studied using large-scale, nonequilibrium molecular dynamics (MD), in the absence and presence of static external electric fields. The field application and larger polymer charges accelerated EPD. Placement of multiple polymers at the same lateral displacement from the surface reduced average deposition times due to "crowding", giving monolayer coverage. These findings were used to develop and validate Brownian dynamics simulations of multilayer polymer EPD in scaled-up systems with larger inter-rod spacings, presenting a generalized picture in qualitative agreement with random sequential adsorption.

  15. Electric field modulation of photoluminescence in cadmium selenide liquid junction solar cells

    SciTech Connect

    Garuthara, R.; Tomkiewicz, M.; Silberstein, R.P.

    1983-11-01

    We have utilized photoluminescence, modulated by small periodic changes of electrode potential, to study the potential distribution at the surface of single crystal cadmium selenide in contact with an electrolyte. We have shown that at reverse bias and at electrode potentials, not far from the flat-band potential, the modulated photoluminescence is described by the ''dead layer'' theory, in which the electric field in the space-charge layer quenches completely the photoluminescence in that region. The electrical characterization of the interface, based on modulated photoluminescence, agrees well with more conventional impedance measurements.

  16. Ovonic switching in tin selenide thin films. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Baxter, C. R.

    1974-01-01

    Amorphous tin selenide thin films which possess Ovonic switching properties were fabricated using vacuum deposition techniques. Results obtained indicate that memory type Ovonic switching does occur in these films the energy density required for switching from a high impedance to a low impedance state is dependent on the spacing between the electrodes of the device. The switching is also function of the magnitude of the applied voltage pulse. A completely automated computer controlled testing procedure was developed which allows precise control over the shape of the applied voltage switching pulse. A survey of previous experimental and theoretical work in the area of Ovonic switching is also presented.

  17. Chemical Bath Deposited Zinc Sulfide Buffer Layers for Copper Indium Gallium Sulfur-selenide Solar Cells and Device Analysis

    SciTech Connect

    Kundu, Sambhu N.; Olsen, Larry C.

    2005-01-03

    Cd free CIGSS thin film solar cell structures with a MgF2/TCO/CGD-ZnS/CIGSS/Mo/SLG structure have been fabricated using chemical bath deposited (CBD)-ZnS buffer layers and high quality CIGSS absorber layers supplied from Shell Solar Industries. The use of CBD-ZnS, which is a higher band gap materials than CdS, improved the quantum efficiency of fabricated cells at lower wavelengths, leading to an increase in short circuit current. The best cell to date yielded an active area (0.43 cm2) efficiency of 13.3%. This paper also presents a discussion of the issues relating to the use of the CBD-ZnS buffer materials for improving device performance.

  18. Phase transition and high temperature thermoelectric properties of copper selenide Cu2-xSe (0 <= x <= 0.25)

    NASA Astrophysics Data System (ADS)

    Xiao, Xing-Xing; Xie, Wen-Jie; Tang, Xin-Feng; Zhang, Qing-Jie

    2011-08-01

    With good electrical properties and an inherently complex crystal structure, Cu2-xSe is a potential “phonon glass electron crystal" thermoelectric material that has previously not attracted much interest. In this study, Cu2-xSe (0 <= x <= 0.25) compounds were synthesized by a melting-quenching method, and then sintered by spark plasma sintering to obtain bulk material. The effect of Cu content on the phase transition and thermoelectric properties of Cu2-xSe were investigated in the temperature range of 300 K-750 K. The results of X-ray diffraction at room temperature show that Cu2-xSe compounds possess a cubic structure with a space group of Fm3m(#225) when 0.15 <= x <= 0.25, whereas they adopt a composite of monoclinic and cubic phases when 0 <= x <= 0.15. The thermoelectric property measurements show that with increasing Cu content, the electrical conductivity decreases, the Seebeck coefficient increases and the thermal conductivity decreases. Due to the relatively good power factor and low thermal conductivity, the nearly stoichiometric Cu2Se compound achieves the highest ZT of 0.38 at 750 K. It is expected that the thermoelectric performance can be further optimized by doping appropriate elements and/or via a nanostructuring approach.

  19. Enhanced Thermoelectricity in High-Temperature β-Phase Copper(I) Selenides Embedded with Cu2Te Nanoclusters.

    PubMed

    Butt, Sajid; Xu, Wei; Farooq, Muhammad U; Ren, Guang K; Zhang, Qinghua; Zhu, Yingcai; Khan, Sajid U; Liu, Lijuan; Yu, Meijuan; Mohmed, Fida; Lin, Yuanhua; Nan, Ce-Wen

    2016-06-22

    We report remarkably enhanced thermoelectric performance of Te doped Cu2Se in midtemperature range. Through ball-milling process followed by spark plasma sintering (SPS), nanoscale Cu2Te clusters were embeded in the matrix of Cu2Se, inducing a drastic enhancement of thermoelectric performance by reducing the thermal conductivity without degrading the power factor. A large ZT value of 1.9 was achieved at 873 K for Cu2Se1.9Te0.1, which is about 2 times larger than that of the pure Cu2Se. The nanoscale heat management by Cu2Te nanoclusters in superionic conductors opens up an avenue for thermoelectric materials research.

  20. Wide range photodetector based on catalyst free grown indium selenide microwires.

    PubMed

    Ali, Zulfiqar; Mirza, Misbah; Cao, Chuanbao; Butt, Faheem K; Tanveer, M; Tahir, Muhammad; Aslam, Imran; Idrees, Faryal; Safdar, Muhammad

    2014-06-25

    We first report the catalyst free growth of indium selenide microwires through a facile approach in a horizontal tube furnace using indium and selenium elemental powders as precursors. The synthesized microwires are γ-phase, high quality, single crystalline and grown along the [112̅0] direction. The wires have a uniform diameter of ∼1 μm and lengths of several micrometers. Photodetectors fabricated from synthesized microwires show reliable and stable photoresponse exhibiting a photoresponsivity of 0.54 A/W, external quantum efficiency of 1.23 at 633 nm with 4 V bias. The photodetector has a reasonable response time of 0.11 s and specific detectivity of 3.94 × 10(10) Jones at 633 nm with a light detection range from 350 to 1050 nm, covering the UV-vis-NIR region. The photoresponse shown by single wire is attributed to direct band gap (Eg = 1.3 eV) and superior single crystalline quality. The photoresponsive studies of single microwires clearly suggest the use of this new and facile growth technique without using catalysts for fabrication of indium selenide microwires in next-generation sensors and detectors for commercial and military applications.

  1. Porous Nickel-Iron Selenide Nanosheets as Highly Efficient Electrocatalysts for Oxygen Evolution Reaction.

    PubMed

    Wang, Zhaoyang; Li, Jiantao; Tian, Xiaocong; Wang, Xuanpeng; Yu, Yang; Owusu, Kwadwo Asare; He, Liang; Mai, Liqiang

    2016-08-03

    Exploring non-noble and high-efficiency electrocatalysts is critical to large-scale industrial applications of electrochemical water splitting. Currently, nickel-based selenide materials are promising candidates for oxygen evolution reaction due to their low cost and excellent performance. In this work, we report the porous nickel-iron bimetallic selenide nanosheets ((Ni0.75Fe0.25)Se2) on carbon fiber cloth (CFC) by selenization of the ultrathin NiFe-based nanosheet precursor. The as-prepared three-dimensional oxygen evolution electrode exhibits a small overpotential of 255 mV at 35 mA cm(-2) and a low Tafel slope of 47.2 mV dec(-1) and keeps high stability during a 28 h measurement in alkaline solution. The outstanding catalytic performance and strong durability, in comparison to the advanced non-noble metal catalysts, are derived from the porous nanostructure fabrication, Fe incorporation, and selenization, which result in fast charge transportation and large electrochemically active surface area and enhance the release of oxygen bubbles from the electrode surface.

  2. Bis[3-methyl-5-(pyridin-2-yl)-1H-pyrazol-4-yl] selenide methanol hemisolvate.

    PubMed

    Seredyuk, Maksym; Sharkina, Natalia O; Gumienna-Kontecka, Elzbieta; Kapshuk, Anatoly A

    2014-02-01

    The asymmetric unit of the title compound, C18H16N6Se·0.5CH3OH, contains two independent mol-ecules of bis-[3-methyl-5-(pyridin-2-yl)-1H-pyrazol-4-yl] selenide with similar C-Se-C bond angles [99.30 (14) and 98.26 (13)°], and a methanol molecule of solvation. In one mol-ecule, the dihedral angles between pyrazole and neighbouring pyridine rings are 18.3 (2) and 15.8 (2)°, and the corresponding angles in the other mol-ecule are 13.5 (2) and 8.3 (2)°. In the crystal, the selenide and solvent mol-ecules are linked by classical O-H⋯N and N-H⋯N hydrogen bonds, as well as by weak C-H⋯O and C-H⋯π inter-actions, forming a three-dimensional supra-molecular architecture.

  3. Characterization of nanostructured iron selenide thin films grown by chemical route at room temperature

    SciTech Connect

    Ubale, A.U.; Sakhare, Y.S.; Belkedkar, M.R.; Singh, Arvind

    2013-02-15

    Highlights: ► Nanostructured FeSe thin films were successfully synthesized at room temperature by CBD method. ► The XRD and EDAX characterization confirms nanocrystalline nature of FeSe. ► The SEM and AFM show microporous morphology with nanorods and nanoplates of FeSe. -- Abstract: Iron selenide thin films have been deposited onto glass substrates by using chemical bath deposition technique. Structural characterization of iron selenide thin films was carried out by means of X-ray diffraction and Fourier transforms infrared spectrum. The morphological characterization of FeSe thin film was carried out using scanning electron microscopy and atomic force microscopy, which revealed porous grain morphology of FeSe with some nano rectangular rods and plates grown on it. The as-deposited thin films exhibited optical band gap energy 2.60 eV. The as deposited FeSe thin films are semiconducting in nature with p-type electrical conductivity. The room temperature electrical resistivity is of the order of 1.1 × 10{sup 5} Ω-cm with activation energy 0.26 and 0.95 eV, respectively, in low and high temperature region.

  4. Transparent metal selenide alloy counter electrodes for high-efficiency bifacial dye-sensitized solar cells.

    PubMed

    Duan, Yanyan; Tang, Qunwei; Liu, Juan; He, Benlin; Yu, Liangmin

    2014-12-22

    The exploration of cost-effective and transparent counter electrodes (CEs) is a persistent objective in the development of bifacial dye-sensitized solar cells (DSSCs). Transparent counter electrodes based on binary-alloy metal selenides (M-Se; M=Co, Ni, Cu, Fe, Ru) are now obtained by a mild, solution-based method and employed in efficient bifacial DSSCs. Owing to superior charge-transfer ability for the I(-) /I3 (-) redox couple, electrocatalytic activity toward I3 (-) reduction, and optical transparency, the bifacial DSSCs with CEs consisting of a metal selenide alloy yield front and rear efficiencies of 8.30 % and 4.63 % for Co0.85 Se, 7.85 % and 4.37 % for Ni0.85 Se, 6.43 % and 4.24 % for Cu0.50 Se, 7.64 % and 5.05 % for FeSe, and 9.22 % and 5.90 % for Ru0.33 Se in comparison with 6.18 % and 3.56 % for a cell with an electrode based on pristine platinum, respectively. Moreover, fast activity onset, high multiple start/stop capability, and relatively good stability demonstrate that these new electrodes should find applications in solar panels.

  5. Biological interaction between transition metals (Ag, Cd and Hg), selenide/sulfide and selenoprotein P.

    PubMed

    Sasakura, C; Suzuki, K T

    1998-09-01

    The interaction between transition metals (Ag+, Cd2+ and Hg2+) and selenium (Se) in the bloodstream was studied in vitro by means of the HPLC--inductively coupled argon plasma-mass spectrometry (ICP MS) method. Transition metal ions and selenide (produced in vitro from selenite in the presence of glutathione) or sulfide (Na2S) formed a (metal-Se/S) complex, which then bound to a plasma protein, selenoprotein P (Sel P), to form a ternary complex, (metal-Se/S)-Sel P. The molar ratios of metals to Se were 1:1 for Hg/Se and Cd/Se, but either 1:1 or 2:1 for Ag/Se, depending on the ratio of their doses. The results indicate that the interaction between transition metals and Se occurs through the general mechanism, i.e., transition metal ions and selenide form the unit complex (metal-Se)n, and then the complex binds to selenoprotein P to form the ternary complex ¿(metal-Se)n¿m--seleno-protein P in the bloodstream.

  6. Thermochemically evolved nanoplatelets of bismuth selenide with enhanced thermoelectric figure of merit

    SciTech Connect

    Ali, Zulfiqar; Cao, Chuanbao Butt, Faheem K.; Tahir, Muhammad; Tanveer, M.; Aslam, Imran; Rizwan, Muhammad; Idrees, Faryal; Khalid, Syed; Butt, Sajid

    2014-11-15

    We firstly present a simple thermochemical method to fabricate high-quality Bi{sub 2}Se{sub 3} nanoplatelets with enhanced figure of merit using elemental bismuth and selenium powders as precursors. The crystal structure of as synthesized products is characterized via X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM) measurements. Morphological and chemical synthetic parameters are investigated through a series of experiments; thickness and composition of the platelets are well controlled in large scale production. Subsequently spark plasma sintering (SPS) is performed to fabricate n-type nanostructured bulk thermoelectric materials. Raman Spectroscopy of the two selected samples with approximately of 50 and 100 nm thicknesses shows three vibrational modes. The lower thickness sample exhibits the maximum red shift of about 2.17 cm{sup -1} and maximum broadening of about 10 cm{sup -1} by in-plane vibrational mode E{sup 2}{sub g}. The enhanced value of figure of merit ∼0.41 is obtained for pure phase bismuth selenide to the best of our knowledge. We observe metallic conduction behavior while semiconducting behavior for nanostructured bismuth selenide is reported elsewhere which could be due to different synthetic techniques adopted. These results clearly suggest that our adopted synthetic technique has profound effect on the electronic and thermoelectric transport properties of this material.

  7. Methylselenol formed by spontaneous methylation of selenide is a superior selenium substrate to the thioredoxin and glutaredoxin systems.

    PubMed

    Fernandes, Aristi P; Wallenberg, Marita; Gandin, Valentina; Misra, Sougat; Tisato, Francesco; Marzano, Cristina; Rigobello, Maria Pia; Kumar, Sushil; Björnstedt, Mikael

    2012-01-01

    Naturally occurring selenium compounds like selenite and selenodiglutathione are metabolized to selenide in plants and animals. This highly reactive form of selenium can undergo methylation and form monomethylated and multimethylated species. These redox active selenium metabolites are of particular biological and pharmacological interest since they are potent inducers of apoptosis in cancer cells. The mammalian thioredoxin and glutaredoxin systems efficiently reduce selenite and selenodiglutathione to selenide. The reactions are non-stoichiometric aerobically due to redox cycling of selenide with oxygen and thiols. Using LDI-MS, we identified that the addition of S-adenosylmethionine (SAM) to the reactions formed methylselenol. This metabolite was a superior substrate to both the thioredoxin and glutaredoxin systems increasing the velocities of the nonstoichiometric redox cycles three-fold. In vitro cell experiments demonstrated that the presence of SAM increased the cytotoxicity of selenite and selenodiglutathione, which could neither be explained by altered selenium uptake nor impaired extra-cellular redox environment, previously shown to be highly important to selenite uptake and cytotoxicity. Our data suggest that selenide and SAM react spontaneously forming methylselenol, a highly nucleophilic and cytotoxic agent, with important physiological and pharmacological implications for the highly interesting anticancer effects of selenium.

  8. Detection of mycobacterial DNA by a specific and simple lateral flow assay incorporating cadmium selenide quantum dots.

    PubMed

    Cimaglia, Fabio; Liandris, Emmanouil; Gazouli, Maria; Sechi, Leonardo; Chiesa, Maurizio; De Lorenzis, Enrico; Andreadou, Margarita; Taka, Styliani; Mataragka, Antonia; Ikonomopoulos, John

    2015-12-01

    Cadmium selenide quantum dots have been incorporated to a lateral flow assay for the specific and very simple detection of different mycobacterial DNA targets within only a few minutes, bypassing the complexity of conventional DNA hybridization assays. The method extends our previous work on protein detection using an identical procedure.

  9. Molecular geometry and polarizability of small cadmium selenide clusters from all-electron ab initio and Density Functional Theory calculations.

    PubMed

    Karamanis, Panaghiotis; Maroulis, George; Pouchan, Claude

    2006-02-21

    We have calculated molecular geometries and electric polarizabilities for small cadmium selenide clusters. Our calculations were performed with conventional ab initio and density functional theory methods and Gaussian-type basis sets especially designed for (CdSe)(n). We find that the dipole polarizability per atom converges rapidly to the bulk value.

  10. Optical and electronic properties of layer-by-layer and composite polyaniline-cadmium selenide quantum dot films

    NASA Astrophysics Data System (ADS)

    Ayub, Ambreen; Shakoor, Abdul; Elahi, Asmat; Rizvi, Tasneem Zahra

    2015-08-01

    Two organic-inorganic hybrid films of intrinsically conducting polymer; polyaniline and cadmium selenide quantum dots were prepared. One by layer-by-layer deposition of polyaniline and cadmium selenide films on PEDOT-PSS/ITO coated glass substrate (ITO/PEDOT-PSS/PANI/CdSe) and other by depositing polyaniline-cadmium selenide quantum dots composite film on the same substrate (ITO/PEDOT-PSS/PANI-CdSe) using spin coating technique. Pure polyaniline, cadmium selenide quantum dots and their composites thus obtained were characterized using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and UV/VIS/NIR absorption spectroscopy. The surface morphologies were studied by Scanning Electron Microscopy (SEM). The diode performance parameters were compared and contrasted for the two devices obtained by different deposition routes. J-V characteristics of these devices showed a rectifying contact with Al metal, however with variation in performance parameters like barrier height, ideality factor and reverse saturation current the ITO/PEDOT-PSS/PANI-CdSe/Al device exhibited better diode performance as compared to ITO/PEDOT-PSS/PANI/CdSe/Al device.

  11. Copper-tantalum alloy

    DOEpatents

    Schmidt, Frederick A.; Verhoeven, John D.; Gibson, Edwin D.

    1986-07-15

    A tantalum-copper alloy can be made by preparing a consumable electrode consisting of an elongated copper billet containing at least two spaced apart tantalum rods extending longitudinally the length of the billet. The electrode is placed in a dc arc furnace and melted under conditions which co-melt the copper and tantalum to form the alloy.

  12. Demystifying Controlling Copper Corrosion

    EPA Science Inventory

    The LCR systematically misses the highest health and corrosion risk sites for copper. Additionally, there are growing concerns for WWTP copper in sludges and discharge levels. There are many corrosion control differences between copper and lead. This talk explains the sometimes c...

  13. [Copper IUDs (author's transl)].

    PubMed

    Thiery, M

    1983-10-01

    Following initial development of the Grafenberg ring in the 1920's, IUDs fell into disuse until the late 1950s, when plastic devices inserted using new technology began to gain worldwide acceptance. Further research indicated that copper had a significant antifertility effect which increased with increasing surface area, and several copper IUDs were developed and adapted, including the Copper T 200, the Copper T 220C, and the Copper T 380 A, probably the most effective yet. The Gravigard and Multiload are 2 other copper devices developed according to somewhat different principles. Copper devices are widely used not so much because of their great effectiveness as because of their suitability for nulliparous patients and their ease of insertion, which minimizes risk of uterine perforation. Records of 2584 women using Copper IUDs for 7190 women-years and 956 women using devices without copper for 6059 women-years suggest that the copper devices were associated with greater effectiveness and fewer removals for complications. Research suggests that the advantages of copper IUDs become more significant with increased duration of use. Contraindications to copper devices include allergy to copper and hepatolenticular degeneration. No carcinogenic or teratogenic effect of copper devices has been found, but further studies are needed to rule out other undesirable effects. Significant modifications of copper devices in recent years have been developed to increase their effectiveness, prolong their duration of usefulness, facilitate insertion and permit insertion during abortion or delivery. The upper limit of the surface area of copper associated with increased effectiveness appears to be between 200-300 sq mm, and at some point increases in copper exposure may provoke expulsion of the IUD. The duration of fertility inhibition of copper IUDs is usually estimated at 2-3 years, but recent research indicates that it may be 6-8 years, and some devices may retain copper surface

  14. Acute treatment with bis selenide, an organic compound containing the trace element selenium, prevents memory deficits induced by reserpine in rats.

    PubMed

    Bortolatto, Cristiani Folharini; Guerra Souza, Ana Cristina; Wilhelm, Ethel Antunes; Nogueira, Cristina Wayne

    2013-01-01

    Taking into account the promising pharmacological actions of (Z)-2,3-bis(4-chlorophenylselanyl) prop-2-en-1-ol) (bis selenide), an organic compound containing the trace element selenium, and the constant search for drugs that improve the cognitive performance, the objective of the present study was to investigate whether bis selenide treatment ameliorates memory deficits induced by reserpine in rats. For this aim, male adult rats received a single subcutaneous injection of reserpine (1 mg/kg), a biogenic amine-depleting agent used to induce memory deficit. After 24 h, bis selenide at doses of 25 and 50 mg/kg was administered to rats by intragastric route, and 1 h later, the animals were submitted to behavior tasks. The effects of acute administration of bis selenide on memory were evaluated by social recognition, step-down passive avoidance, and object recognition paradigms. Exploratory and locomotor activities of rats were determined using the open-field test. Analysis of data revealed that the social memory disruption caused by reserpine was reversed by bis selenide at both doses. In addition, bis selenide, at the highest dose, prevented the memory deficit resulting from reserpine administration to rats in step-down passive avoidance and object recognition tasks. No significant alterations in locomotor and exploratory behaviors were found in animals treated with reserpine and/or bis selenide. Results obtained from distinct memory behavioral paradigms revealed that an acute treatment with bis selenide attenuated memory deficits induced by reserpine in rats.

  15. Bismuth selenides from St. Andreasberg, Germany: an oxidised five-element style of mineralisation and its relation to post-Variscan vein-type deposits of central Europe

    NASA Astrophysics Data System (ADS)

    Cabral, Alexandre Raphael; Ließmann, Wilfried; Jian, Wei; Lehmann, Bernd

    2016-12-01

    Carbonate veinlets at Roter Bär, a former underground mine in the polymetallic St. Andreasberg vein district of the Harz Mountains, Germany, host selenide minerals that are characterised as Bi-Ag-bearing clausthalite (PbSe), tiemannite (HgSe), guanajuatite (Bi2Se3) and a number of selenides of Bi, Zn, Cu, Ag and Pd. An unnamed Bi-Pb-Ag selenide species with some Hg and Cu, ideally Bi4Pb3Ag2Se10, is reported here. Specular hematite is disseminated within the clausthalite, at the marginal zones of which other selenide minerals are located. The occurrence of bohdanowiczite (AgBiSe2) and umangite (Cu3Se2) constrains the formation temperature to ≤120 °C, and the selenide-hematite assemblage (plus barite in the carbonate gangue) identifies highly oxidised conditions. Selenide assemblages of Pb, Bi, Ag, with and without Co and Ni, occur in many parts of the Variscan basement of central Europe (Harz, Erzgebirge, Schwarzwald and Bohemian Massif) and represent a high-oxidation variety of five-element (Ag-As-Bi-Co-Ni) veins.

  16. Heterogeneous nanocomposites of silver selenide and hollow platinum nanoparticles toward methanol oxidation reaction

    NASA Astrophysics Data System (ADS)

    Cui, Penglei; He, Hongyan; Liu, Hui; Zhang, Suojiang; Yang, Jun

    2016-09-01

    Making use of the electronic coupling between different domains in composite nanomaterials is an effective way to enhance the activity of electrocatalysts. Herein, we demonstrate the preparation of nanocomposites consisting of silver selenide (Ag2Se) and platinum (Pt) nanoparticles with a hollow interior by combining the inside-out diffusion of Ag in core-shell Ag-Pt nanoparticles with the synthesis of highly active hydrophobic Se species. In specific, the Ag2Se-hPt nanocomposites are found to have superior activity and stability for methanol oxidation reaction in an acidic condition due to the strong electronic coupling effect between semiconductor and metal domains. This strategy may provide a greener and less expensive way to the large-scale synthesis of Pt-based nanocomposites, and might be used to generate other heterogeneous nanomaterials with technological importance.

  17. Silica encapsulation of thiol-stabilized lead selenide (PbSe) quantum dots in aqueous solution.

    PubMed

    Primera-Pedrozo, Oliva M; Ates, Mehmet; Arslan, Zikri

    2013-07-01

    Silica encapsulation of lead selenide quantum dots (PbSe QDs) in aqueous solution is reported. Thioglycolic acid (TGA) stabilized PbSe QDs were modified with 3-mercaptopropyl trimethoxysilane (MPS) through vigorous stirring in water for 18-24 h in alkaline solution (pH 10.4-10.6). Silica shell was developed by controlled deposition and precipitation of silicates from sodium silicate solution onto MPS modified QDs surfaces. TEM images showed multiple PbSe QDs encapsulated in silica shell. The size of PbSe-SiO2 core-shell nanocrystals was estimated to be 25-30 nm by TEM. Elemental compositions (Pb, Se and Si) were investigated by EDX analysis. The purified colloids of PbSe-SiO2 QDs were stable for months when kept at 4 °C.

  18. Revealing the preferred interlayer orientations and stackings of two-dimensional bilayer gallium selenide crystals.

    PubMed

    Li, Xufan; Basile, Leonardo; Yoon, Mina; Ma, Cheng; Puretzky, Alexander A; Lee, Jaekwang; Idrobo, Juan C; Chi, Miaofang; Rouleau, Christopher M; Geohegan, David B; Xiao, Kai

    2015-02-23

    Characterizing and controlling the interlayer orientations and stacking orders of two-dimensional (2D) bilayer crystals and van der Waals (vdW) heterostructures is crucial to optimize their electrical and optoelectronic properties. The four polymorphs of layered gallium selenide (GaSe) crystals that result from different layer stackings provide an ideal platform to study the stacking configurations in 2D bilayer crystals. Through a controllable vapor-phase deposition method, bilayer GaSe crystals were selectively grown and their two preferred 0° or 60° interlayer rotations were investigated. The commensurate stacking configurations (AA' and AB stacking) in as-grown bilayer GaSe crystals are clearly observed at the atomic scale, and the Ga-terminated edge structure was identified using scanning transmission electron microscopy. Theoretical analysis reveals that the energies of the interlayer coupling are responsible for the preferred orientations among the bilayer GaSe crystals.

  19. Temperature induced phonon behaviour in germanium selenide thin films probed by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Taube, A.; Łapińska, A.; Judek, J.; Wochtman, N.; Zdrojek, M.

    2016-08-01

    Here we report a detailed study of temperature-dependent phonon properties of exfoliated germanium selenide thin films (several tens of nanometers thick) probed by Raman spectroscopy in the 70-350 K temperature range. The temperature-dependent behavior of the positions and widths of the Raman modes was nonlinear. We concluded that the observed effects arise from anharmonic phonon-phonon interactions and are explained by the phenomenon of optical phonon decay into acoustic phonons. At temperatures above 200 K, the position of the Raman modes tended to be linearly dependent, and the first order temperature coefficients χ were  -0.0277, -0.0197 and  -0.031 cm-1 K-1 for B 3g , A g(1) and A g(2) modes, respectively.

  20. Resonance enhancement of nonlinear photoluminescence in gallium selenide and related compounds

    SciTech Connect

    Angermann, Ch; Karich, P; Kador, Lothar; Allakhverdiev, K R; Baykara, T; Salaev, E Yu

    2012-05-31

    Maker fringe experiments on the layered chalcogenide semiconductor gallium selenide (GaSe) with weak cw diode lasers are presented. It is demonstrated that nonlinear photoluminescence emitted by this material and by the similar compound GaSe{sub 0.9}S{sub 0.1} under illumination with a 632.8-nm He - Ne laser shows very strong resonance enhancement upon heating when the absorption edge and exciton levels are shifted towards the laser line. The photoluminescence appears to be strongest when the energy level of the direct exciton, which emits it, is resonant with the photon energy of the laser. The previously observed enhancement of the photoluminescence by electric fields is interpreted in this context.

  1. The effect of structural dimensionality on the electrocatalytic properties of the nickel selenide phase.

    PubMed

    Kukunuri, Suresh; Krishnan, M Reshma; Sampath, S

    2015-09-28

    Nickel selenide (NiSe) nanostructures possessing different morphologies of wires, spheres and hexagons are synthesized by varying the selenium precursors, selenourea, selenium dioxide (SeO2) and potassium selenocyanate (KSeCN), respectively, and are characterized using X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy and scanning electron microscopy techniques. Electrical measurements of a single nanowire and a hexagon carried out on devices fabricated by the focused ion beam (FIB) technique depict the semiconducting nature of NiSe and its ability to act as a visible light photodetector. The three different morphologies are used as catalysts for hydrogen evolution (HER), oxygen reduction (ORR) and glucose oxidation reactions. The wire morphology is found to be better than that of spheres and hexagons for all the reactions. Among the reactions studied, NiSe is found to be good for HER and glucose oxidation while ORR seems to terminate at the peroxide stage.

  2. In vivo synthesis of europium selenide nanoparticles and related cytotoxicity evaluation of human cells.

    PubMed

    Kim, Eun Bee; Seo, Ji Min; Kim, Gi Wook; Lee, Sang Yup; Park, Tae Jung

    2016-12-01

    Nanotechnology strives to combine new materials for development of noble nanoparticles. As the nanoparticles exhibit unique optical, electronic, and magnetic properties depending on their composition, developing safe, cost-effective and environmentally friendly technologies for the synthesis have become an important issue. In this study, in vivo synthesis of europium selenide (EuSe) nanoparticles was performed using recombinant Escherichia coli cells expressing heavy-metal binding proteins, phytochelatin synthase and metallothionein. The formation of EuSe nanoparticles was confirmed by using UV-vis spectroscopy, spectrofluorometry, X-ray diffraction, energy dispersive X-ray and transmission electron microscopy. The synthesized EuSe nanoparticles exhibited high fluorescence intensities as well as strong magnetic properties. Furthermore, anti-cancer effect of EuSe nanoparticles against cancer cell lines was investigated. This strategy for the biogenic synthesis of nanoparticles has a great potential as bioimaging tools and drug carrying agents in biomedical fields due to its simplicity and nontoxicity.

  3. Simulations of silver-doped germanium-selenide glasses and their response to radiation

    PubMed Central

    2014-01-01

    Chalcogenide glasses doped with silver have many applications including their use as a novel radiation sensor. In this paper, we undertake the first atomistic simulation of radiation damage and healing in silver-doped Germanium-selenide glass. We jointly employ empirical potentials and ab initio methods to create and characterize new structural models and to show that they are in accord with many experimental observations. Next, we simulate a thermal spike and track the evolution of the radiation damage and its eventual healing by application of a simulated annealing process. The silver network is strongly affected by the rearrangements, and its connectivity (and thus contribution to the electrical conductivity) change rapidly in time. The electronic structure of the material after annealing is essentially identical to that of the initial structure. PMID:25426005

  4. The growth of zinc selenide single crystals by physical vapor transport in microgravity

    NASA Technical Reports Server (NTRS)

    Anderson, Elmer E.; Rosenberger, Franz E.; Cheng, Hai-Yuin

    1990-01-01

    Growth and characterization studies will be performed on zinc selenide single crystals. The high temperature outgassing behavior of the silica ampoule material will be studied in order to develop a cleaning and bake-out procedure that will minimize the amount of impurities introduced into the vapor from the ampoule materials and in particular during the seal-off procedure. The outgassing behavior of the ZnSe starting material will be studied during high vacuum refinement at elevated temperatures in order to develop a temperature pressure program that will optimize the removal of impurities while minimizing a shift in stoichiometry due to preferred evaporation of the higher fugacity component. The mass spectrometer system was completed, and after calibration, will be used to perform the above tasks. The system and its operation is described in detail.

  5. Dynamic observation of phase transformation behaviors in indium(III) selenide nanowire based phase change memory.

    PubMed

    Huang, Yu-Ting; Huang, Chun-Wei; Chen, Jui-Yuan; Ting, Yi-Hsin; Lu, Kuo-Chang; Chueh, Yu-Lun; Wu, Wen-Wei

    2014-09-23

    Phase change random access memory (PCRAM) has been extensively investigated for its potential applications in next-generation nonvolatile memory. In this study, indium(III) selenide (In2Se3) was selected due to its high resistivity ratio and lower programming current. Au/In2Se3-nanowire/Au phase change memory devices were fabricated and measured systematically in an in situ transmission electron microscope to perform a RESET/SET process under pulsed and dc voltage swept mode, respectively. During the switching, we observed the dynamic evolution of the phase transformation process. The switching behavior resulted from crystalline/amorphous change and revealed that a long pulse width would induce the amorphous or polycrystalline state by different pulse amplitudes, supporting the improvement of the writing speed, retention, and endurance of PCRAM.

  6. Optoelectronic and low temperature thermoelectric studies on nanostructured thin films of silver gallium selenide

    SciTech Connect

    Jacob, Rajani Philip, Rachel Reena Nazer, Sheeba Abraham, Anitha Nair, Sinitha B.; Pradeep, B.; Urmila, K. S.; Okram, G. S.

    2014-01-28

    Polycrystalline thin films of silver gallium selenide were deposited on ultrasonically cleaned soda lime glass substrates by multi-source vacuum co-evaporation technique. The structural analysis done by X-ray diffraction ascertained the formation of nano structured tetragonal chalcopyrite thin films. The compound formation was confirmed by X-ray photo-electron spectroscopy. Atomic force microscopic technique has been used for surface morphological analysis. Direct allowed band gap ∼1.78eV with high absorption coefficient ∼10{sup 6}/m was estimated from absorbance spectra. Low temperature thermoelectric effects has been investigated in the temperature range 80–330K which manifested an unusual increase in Seebeck coefficient with negligible phonon drag toward the very low and room temperature regime. The electrical resistivity of these n-type films was assessed to be ∼2.6Ωm and the films showed good photo response.

  7. Deposition of heteroepitaxial layer of cadmium selenide and telluride on indium arsenide

    SciTech Connect

    Buttaev, M.S.; Gasanov, N.G.; Gasanova, R.N.; Magomedov, K.A.

    1986-04-01

    The authors have investigated how the technological deposition regimes influence the surface morphology, growth rate, and structural perfection of heteroepitaxial layers of cadmium selenide and telluride grown on the polar faces of indium arsenide. Investigation of the process of obtaining layers of CdSe on InAs revealed that the orientation of the polar faces of the substrate influences both the morphology of the surface layer and the rate of growth. Photomicrographs are shown of the surfaces of layers with different growth figures. A phenomenum is explained that does not enable one to grow CdTe layers on InAs at high temperatures; this complicates the choice of particular parameters for the deposition process and rules out the use of indium arsenide as a substrate.

  8. Particle-rod hybrids: growth of arachidic acid molecular rods from capped cadmium selenide nanoparticles.

    PubMed

    Chen, Dongzhong; Wang, Ruomiao; Arachchige, Indika; Mao, Guangzhao; Brock, Stephanie L

    2004-12-22

    This communication describes a spin-coating method to nucleate organic molecular rods of uniform size from an inorganic nanoparticle at a solid surface. The particle-rod hybrid structure spontaneously forms when a film is spin coated from a mixed 2-propanol solution of arachidic acid (AA) and nanoparticles of cadmium selenide capped by mercaptoundecanoic acid (MUA-CdSe) on graphite. AFM images show that MUA-CdSe nanoparticles nucleate single crystalline rods of AA with a cross section of a single unit cell of the C-form. The solution-based process potentially allows the precise tuning of the wetting profile of the solution on the surface-attached nanoparticle, which provides the reservoir for the growth of the single crystalline rods. The results suggest that nanoparticles can be regarded as nanoseeds for the nucleation of guest crystals. It should be possible to further functionalize the AA rods by electrostatic complexation with metal or organic ions.

  9. Effect of cadmium selenide quantum dots on the dielectric and physical parameters of ferroelectric liquid crystal

    NASA Astrophysics Data System (ADS)

    Singh, D. P.; Gupta, S. K.; Manohar, R.; Varia, M. C.; Kumar, S.; Kumar, A.

    2014-07-01

    The effect of cadmium selenide quantum dots (CdSe QDs) on the dielectric relaxation and material constants of a ferroelectric liquid crystal (FLC) has been investigated. Along with the characteristic Goldstone mode, a new relaxation mode has been induced in the FLC material due to the presence of CdSe QDs. This new relaxation mode is strongly dependent on the concentration of CdSe QDs but is found to be independent of the external bias voltage and temperature. The material constants have also been modified remarkably due to the presence of CdSe QDs. The appearance of this new relaxation phenomenon has been attributed to the concentration dependent interaction between CdSe QDs and FLC molecules.

  10. A Rapid and Cost-Effective Laser Based Synthesis of High Purity Cadmium Selenide Quantum Dots.

    PubMed

    Gondall, M A; Qahtan, Talal F; Dastageer, M A; Yamani, Z H; Anjum, D H

    2016-01-01

    A rapid and cost effective method is developed to synthesize high purity cadmium Selenide (CdSe) quantum dots in acetone medium using second harmonic of Nd:YAG nanosecond pulsed laser of 532 nm wavelength. The thermal agglomeration due the nanosecond pulse duration of the laser was successfully eliminated by using unfocussed laser beam and thereby providing a favorable conditions for the synthesis of quantum dots having the grain size of 3 nm. The morphological and optical characterizations like XRD, HRTEM, optical absorption of the synthesized CdSe quantum dots, reveal that the material possesses the similar characteristics of the one synthesized through cumbersome wet chemical methods. Relative to the CdSe bulk material, the synthesized CdSe quantum dots showed a blue shift in the measured band gap energy from near infrared spectral region to visible region, making this material very attractive for many solar energy harvesting applications like photo-catalysis and solar cells.

  11. Effect of cadmium selenide quantum dots on the dielectric and physical parameters of ferroelectric liquid crystal

    SciTech Connect

    Singh, D. P.; Gupta, S. K.; Manohar, R.; Varia, M. C.; Kumar, S.; Kumar, A.

    2014-07-21

    The effect of cadmium selenide quantum dots (CdSe QDs) on the dielectric relaxation and material constants of a ferroelectric liquid crystal (FLC) has been investigated. Along with the characteristic Goldstone mode, a new relaxation mode has been induced in the FLC material due to the presence of CdSe QDs. This new relaxation mode is strongly dependent on the concentration of CdSe QDs but is found to be independent of the external bias voltage and temperature. The material constants have also been modified remarkably due to the presence of CdSe QDs. The appearance of this new relaxation phenomenon has been attributed to the concentration dependent interaction between CdSe QDs and FLC molecules.

  12. Preparation of cadmium selenide-polyolefin composites from functional phosphine oxides and ruthenium-based metathesis.

    PubMed

    Skaff, Habib; Ilker, M Firat; Coughlin, E Bryan; Emrick, Todd

    2002-05-22

    Cadmium selenide nanoparticles, prepared by known methods, were stabilized with functional phosphine oxide 1, then used to support the polymerization of cyclic olefins radially outward from the surface by ruthenium-catalyzed ring-opening metathesis polymerization (ROMP). The conversion of compound 1 into the new metathesis catalyst 3 by carbene exchange and the subsequent polymerization of cyclic olefins were observed spectroscopically by (1)H NMR to afford for example CdSe-polycyclooctene composite 6. Transmission electron micrographs on thin films of these composites showed good nanoparticle dispersion. This is in stark contrast to the substantial nanoparticle aggregation observed when similar polymerizations were performed in the presence of conventional TOPO-covered nanoparticles. The methods reported here to prepare composite product 6 are applicable to other cyclic olefins, and suggest that this chemistry will be useful for incorporating CdSe nanoparticles into a wide variety of polymer matrices.

  13. Transparent nickel selenide alloy counter electrodes for bifacial dye-sensitized solar cells exceeding 10% efficiency.

    PubMed

    Duan, Yanyan; Tang, Qunwei; He, Benlin; Li, Ru; Yu, Liangmin

    2014-11-07

    In the current work, we report a series of bifacial dye-sensitized solar cells (DSSCs) that provide power conversion efficiencies of more than 10% from bifacial irradiation. The device comprises an N719-sensitized TiO2 anode, a transparent nickel selenide (Ni-Se) alloy counter electrode (CE), and liquid electrolyte containing I(-)/I3(-) redox couples. Because of the high optical transparency, electron conduction ability, electrocatalytic activity of Ni-Se CEs, as well as dye illumination, electron excitation and power conversion efficiency have been remarkably enhanced. Results indicate that incident light from a transparent CE has a compensation effect to the light from the anode. The impressive efficiency along with simple preparation of the cost-effective Ni-Se alloy CEs highlights the potential application of bifacial illumination technique in robust DSSCs.

  14. Acute copper toxicity following copper glycinate injection.

    PubMed

    Oon, S; Yap, C-H; Ihle, B U

    2006-11-01

    We present a patient who developed multi-organ failure due to severe copper toxicity following attempted suicide by s.c. injection of copper glycinate. Acute copper toxicity is rare in the developed world, although it occurs more frequently in developing world countries, where it is a common mode of suicide. Acute toxicity usually results from oral ingestion and there are several local and systemic effects. Specific management can be difficult as there is little evidence regarding the efficacy of chelating agents in acute toxicity.

  15. Controllable synthesis of metal selenide heterostructures mediated by Ag2Se nanocrystals acting as catalysts.

    PubMed

    Zhou, Jiangcong; Huang, Feng; Xu, Ju; Wang, Yuansheng

    2013-10-21

    Ag2Se nanocrystals were demonstrated to be novel semiconductor mediators, or in other word catalysts, for the growth of semiconductor heterostructures in solution. This is a result of the unique feature of Ag2Se as a fast ion conductor, allowing foreign cations to dissolve and then to heterogrow the second phase. Using Ag2Se nanocrystals as catalysts, dimeric metal selenide heterostructures such as Ag2Se-CdSe and Ag2Se-ZnSe, and even multi-segment heterostructures such as Ag2Se-CdSe-ZnSe and Ag2Se-ZnSe-CdSe, were successfully synthesized. Several interesting features were found in the Ag2Se based heterogrowth. At the initial stage of heterogrowth, a layer of the second phase forms on the surface of an Ag2Se nanosphere, with a curved junction interface between the two phases. With further growth of the second phase, the Ag2Se nanosphere tends to flatten the junction surface by modifying its shape from sphere to hemisphere in order to minimize the conjunct area and thus the interfacial energy. Notably, the crystallographic relationship of the two phases in the heterostructure varies with the lattice parameters of the second phase, in order to reduce the lattice mismatch at the interface. Furthermore, a small lattice mismatch at the interface results in a straight rod-like second phase, while a large lattice mismatch would induce a tortuous product. The reported results may provide a new route for developing novel selenide semiconductor heterostructures which are potentially applicable in optoelectronic, biomedical, photovoltaic and catalytic fields.

  16. Optical and morphological characteristics of zinc selenide-zinc sulfide solid solution crystals

    NASA Astrophysics Data System (ADS)

    Singh, N. B.; Su, Ching-Hua; Arnold, Bradley; Choa, Fow-Sen

    2016-10-01

    Experiments were performed to study the effect of point defects on the optical and morphological characteristics of zinc selenide-zinc sulfide ZnSe-ZnS (ZnSexS(1-x)) solid solution crystals grown under terrestrial (1-g) condition. We used the composition ZnSe0.91S0.09 and ZnSe0.73S0.27 for the detailed studies. Crystals of 8 mm and 12 mm diameter were grown using physical vapor transport methods. These crystals did not exhibit gross defects such as voids, bubbles or precipitates. The photoluminescence spectra indicated strong red emission for the 610-630-nm wavelength region in both crystals. This emission could be explained on the basis of high energy irradiation of Zn selenide. For the ZnSe0.73S0.27 crystal, absorption starts at a lower wavelength range (300 nm) when compared to the ZnSe0.91S0.09 crystal presumably due to the much higher bandgap of ZnS than that of ZnSe. Sharp peaks at 451 and 455 nm were observed for both samples corresponding to the band edge transitions, followed by a strong peak at 632 nm. These results were consistent with the observations based on Raman spectroscopy studies. Under 532-nm laser illumination both transverse optical (TO) and longitudinal optical (LO) phonon peaks appeared at Raman shifts of 220 and 280 Δcm-1, respectively. These peaks are similar to those observed for pure ZnSe Raman spectra for which TO and LO occur at 200 and 250 Δcm-1 for the x-axis (first order) polarization.

  17. Reaction chemistry and ligand exchange at cadmium-selenide nanocrystal surfaces.

    PubMed

    Owen, Jonathan S; Park, Jungwon; Trudeau, Paul-Emile; Alivisatos, A Paul

    2008-09-17

    The surface chemistry of cadmium selenide nanocrystals, prepared from tri-n-octylphosphine selenide and cadmium octadecylphosphonate in tri-n-octylphosphine oxide, was studied with 1H and {1H}31P NMR spectroscopy as well as ESI-MS and XPS. The identity of the surface ligands was inferred from reaction of nanocrystals with Me3Si-X (X = -S-SiMe3, -Se-SiMe3, -Cl and -S-(CH2CH2O)4OCH3)) and unambiguous assignment of the organic byproducts, O,O'-bis(trimethylsilyl)octadecylphosphonic acid ester and O,O'-bis(trimethylsilyl)ocatdecylphosphonic acid anhydride ester. Nanocrystals isolated from these reactions have undergone exchange of the octadecylphosphonate ligands for -X as was shown by 1H NMR (X = -S-(CH2CH2O)4OCH3) and XPS (X = -Cl). Addition of free thiols to as prepared nanocrystals results in binding of the thiol to the particle surface and quenching of the nanocrystal fluorescence. Isolation of the thiol-ligated nanocrystals shows this chemisorption proceeds without displacement of the octadecylphosphonate ligands, suggesting the presence of unoccupied Lewis-acidic sites on the particle surface. In the presence of added triethylamine, however, the octadecylphosphonate ligands are readily displaced from the particle surface as was shown with 1H and {1H}31P NMR. These results, in conjunction with previous literature reports, indicate that as-prepared nanocrystal surfaces are terminated by X-type binding of octadecylphosphonate moieties to a layer of excess cadmium ions.

  18. Transition from Molecular Vibrations to Phonons in Atomically Precise Cadmium Selenide Quantum Dots.

    PubMed

    Beecher, Alexander N; Dziatko, Rachel A; Steigerwald, Michael L; Owen, Jonathan S; Crowther, Andrew C

    2016-12-28

    We use micro-Raman spectroscopy to measure the vibrational structure of the atomically precise cadmium selenide quantum dots Cd35Se20X30L30, Cd56Se35X42L42, and Cd84Se56X56L56. These quantum dots have benzoate (X) and n-butylamine (L) ligands and tetrahedral (Td) shape with edges that range from 1.7 to 2.6 nm in length. Investigating this previously unexplored size regime allows us to identify the transition from molecular vibrations to bulk phonons in cadmium selenide quantum dots for the first time. Room-temperature Raman spectra have broad CdSe peaks at 175 and 200 cm(-1). Density functional theory calculations assign these peaks to molecular surface and interior vibrational modes, respectively, and show that the interior, surface, and ligand atom motion is strongly coupled. The interior peak intensity increases relative to the surface peak as the cluster size increases due to the relative increase in the polarizability of interior modes with quantum dot size. The Raman spectra do not change with temperature for molecular Cd35Se20X30L30, while the interior peak narrows and shifts to higher energy as temperature decreases for Cd84Se56X56L56, a spectral evolution typical of a phonon. This result shows that the single bulk unit cell contained within Cd84Se56X56L56 is sufficient to apply a phonon confinement model, and that Cd56Se35X42L42, with its 2.1 nm edge length, marks the boundary between molecular vibrations and phonons.

  19. Copper in developmental stuttering.

    PubMed

    Alm, Per A

    2005-01-01

    It has previously been reported that men with developmental stuttering showed reduced concentration of copper in the blood, and a negative correlation between the copper level and the severity of stuttering. Disorders of copper metabolism may result in dysfunction of the basal ganglia system and dystonia, a motor disorder sharing some traits of stuttering. It has been shown that copper ions affect the dopamine and the GABA systems. With this background we investigated the plasma level of copper, the copper binding protein ceruloplasmin, and the estimated level of free copper in stuttering adults. Sixteen men with developmental stuttering were compared with 16 men without speech problems. The samples were assayed in one batch in a pseudorandom and counterbalanced order. No significant differences were found between stuttering men and the control group in any of the biological variables, and no negative correlation between copper and the general severity of stuttering was shown. On the contrary, an explorative analysis resulted in a positive correlation between high plasma copper and superfluous muscular activity during stuttering (r=0.51, p=0.04). This result indicates that there is no relation between developmental stuttering and low plasma copper in the main population of stuttering adults.

  20. Handling of Copper and Copper Oxide Nanoparticles by Astrocytes.

    PubMed

    Bulcke, Felix; Dringen, Ralf

    2016-02-01

    Copper is an essential trace element for many important cellular functions. However, excess of copper can impair cellular functions by copper-induced oxidative stress. In brain, astrocytes are considered to play a prominent role in the copper homeostasis. In this short review we summarise the current knowledge on the molecular mechanisms which are involved in the handling of copper by astrocytes. Cultured astrocytes efficiently take up copper ions predominantly by the copper transporter Ctr1 and the divalent metal transporter DMT1. In addition, copper oxide nanoparticles are rapidly accumulated by astrocytes via endocytosis. Cultured astrocytes tolerate moderate increases in intracellular copper contents very well. However, if a given threshold of cellular copper content is exceeded after exposure to copper, accelerated production of reactive oxygen species and compromised cell viability are observed. Upon exposure to sub-toxic concentrations of copper ions or copper oxide nanoparticles, astrocytes increase their copper storage capacity by upregulating the cellular contents of glutathione and metallothioneins. In addition, cultured astrocytes have the capacity to export copper ions which is likely to involve the copper ATPase 7A. The ability of astrocytes to efficiently accumulate, store and export copper ions suggests that astrocytes have a key role in the distribution of copper in brain. Impairment of this astrocytic function may be involved in diseases which are connected with disturbances in brain copper metabolism.

  1. Ba2F2Fe(1.5)Se3: An Intergrowth Compound Containing Iron Selenide Layers.

    PubMed

    Driss, Dalel; Janod, Etienne; Corraze, Benoit; Guillot-Deudon, Catherine; Cario, Laurent

    2016-03-21

    The iron selenide compound Ba2F2Fe(1.5)Se3 was synthesized by a high-temperature ceramic method. The single-crystal X-ray structure determination revealed a layered-like structure built on [Ba2F2](2+) layers of the fluorite type and iron selenide layers [Fe(1.5)Se3](2-). These [Fe1.5Se3](2-) layers contain iron in two valence states, namely, Fe(II+) and Fe(III+) located in octahedral and tetrahedral sites, respectively. Magnetic measurements are consistent with a high-spin state for Fe(II+) and an intermediate-spin state for Fe(III+). Moreover, susceptibility and resistivity measurements demonstrate that Ba2F2Fe(1.5)Se3 is an antiferromagnetic insulator.

  2. Tin selenide synthesized by a chemical route: the effect of the annealing conditions in the obtained phase

    NASA Astrophysics Data System (ADS)

    Bernardes-Silva, Ana Cláudia; Mesquita, A. F.; de Moura Neto, E.; Porto, A. O.; de Lima, G. M.; Ardisson, J. D.; Lameiras, F. S.

    2005-09-01

    The effects of different annealing conditions over the tin selenide obtained from a chemical route are presented in this work. The tin selenide was annealed at 300 and 600 °C under hydrogen, nitrogen and argon atmospheres. The materials were characterized by X-ray diffraction and 119Sn Mössbauer spectroscopy. In the 'as synthetized' material a considerably amount of tin oxide (57%) was detected by Mössbauer spectroscopy. After thermal annealing the amount of these oxides varied according to the temperature and atmosphere used. At 600 °C/hydrogen the smallest amount of tin oxide was obtained (20%). These oxides were formed during the synthetic procedure through the hydrolysis of tin chloride used as reagent.

  3. Fluorescence imaging technology (FI) for high-throughput screening of selenide-modified nano-TiO2 catalysts.

    PubMed

    Wang, Liping; Lee, Jianchao; Zhang, Meijuan; Duan, Qiannan; Zhang, Jiarui; Qi, Hailang

    2016-02-18

    A high-throughput screening (HTS) method based on fluorescence imaging (FI) was implemented to evaluate the catalytic performance of selenide-modified nano-TiO2. Chemical ink-jet printing (IJP) technology was reformed to fabricate a catalyst library comprising 1405 (Ni(a)Cu(b)Cd(c)Ce(d)In(e)Y(f))Se(x)/TiO2 (M6Se/Ti) composite photocatalysts. Nineteen M6Se/Tis were screened out from the 1405 candidates efficiently.

  4. Copper-Silicon Bronzes

    DTIC Science & Technology

    1933-05-11

    copper alloys which have good static properties are disa:cinting in their endurance properties. The silicide allo~rs that are given high tensile strength...notched endurance tests and on cast alloys of this type, are lacking. uowever, preliminary reports state that a copper beryllium alloy of about 2 1/2...properties re- main almost the same. Grain size increases with sil- icon. III A study of hardening copper by heat treating its alloys with silicides

  5. Hair copper in intrauterine copper device users.

    PubMed

    Thiery, M; Heyndrickx, A; Uyttersprot, C

    1984-03-01

    The antifertility effect of copper-bearing IUDs is based on continuous release of copper, which is a result of the reaction between the metal and the uterine secretions. Released cupric ions collect in the endometrium and in the uterine fluid but significant accumulation has not been found in the bloodstream or elsewhere. Following Laker's suggestion that hair be used for monitoring essential trace elements, e.g., copper, we checked the copper content of the hair of women wearing copper-bearing IUDs. Samples of untreated pubic hair removed by clipping before diagnostic curettage were obtained from 10 young (24-34 years old), white caucasian females who until then had been wearing an MLCu250 IUD for more than 1 year. Pubes from 10 comparable (sex, age, race) subjects who had never used a Cu-containing device served as controls. The unwashed material was submitted to the toxicology laboratory, where the copper content was assessed by flameless atomic absorption, a technique whose lower limit of measurement lies at a concentration of 0.05 mcg Cu/ml fluid (50 ppb). Hair samples were washed to remove extraneous traces of metal according to the prescriptions of the International Atomic Energy Agency, weighed, and mineralized, after which a small volume (10 mcl) of the diluted fluid was fed into the graphite furnace. Each sample (75-150 mg) was analyzed 4 times, both before and after washing. Since the cleaning procedure reduces the weight of the sample (mainly by the removal of fat, dust, etc.) this explains why the percentage copper content of washed hair is higher than that of unwashed hair belonging to the same subject. The results indicate that there was no significant difference (Mann-Whitney U test) between the mean copper levels of both unwashed and washed pubes from women who were using or had never used an MLCu250 IUD. We therefore conclude that the use of this copper-containing device is not associated with significant accumulation of copper in (pubic) hair.

  6. Extracellular synthesis of cuprous selenide nanospheres by a biological-chemical coupling reduction process in an anaerobic microbial system.

    PubMed

    Yue, Lei; Wang, Jia; Qi, Shiyue; Xin, Baoping

    2016-09-01

    Biosynthesis of metal nanoparticles represents a clean, eco-friendly and sustainable "green chemistry" engineering. Lately, a number of metal selenides were successfully synthesized by biological methods. Here, cuprous selenide (Cu2 Se) nanospheres were prepared under mild conditions by a novel biological-chemical coupling reduction process. The simple process takes place between EDTA-Cu and Na2 SeO3 in presence of an alkaline solution containing NaBH4 and a selenite-reducing bacteria, Pantoea agglomerans. It is noteworthy that the isolated Pantoea agglomerans and Cu(+) ions, where the latter are obtained from reducing Cu(2+) ions by NaBH4 , play a key role, and Cu(+) ions not only can promote the generation of Se(2-) ions as a catalyst, but also can react with Se(2-) ions to form Cu2 Se. XRD pattern, SEM, and TEM images indicated that Cu2 Se nanoparticles were tetragonal crystal structure and the nanospheres diameter were about 100 nm. EDX, UV-vis, and FTIR spectra show that the biosynthesized Cu2 Se nanospheres are wrapped by protein and have a better stability. This work first proposes a new biosynthesis mechanism, and has important reference value for biological preparation of metal selenide nanomaterials. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1264-1270, 2016.

  7. Biogenic nanoparticles: copper, copper oxides, copper sulphides, complex copper nanostructures and their applications.

    PubMed

    Rubilar, Olga; Rai, Mahendra; Tortella, Gonzalo; Diez, Maria Cristina; Seabra, Amedea B; Durán, Nelson

    2013-09-01

    Copper nanoparticles have been the focus of intensive study due to their potential applications in diverse fields including biomedicine, electronics, and optics. Copper-based nanostructured materials have been used in conductive films, lubrification, nanofluids, catalysis, and also as potent antimicrobial agent. The biogenic synthesis of metallic nanostructured nanoparticles is considered to be a green and eco-friendly technology since neither harmful chemicals nor high temperatures are involved in the process. The present review discusses the synthesis of copper nanostructured nanoparticles by bacteria, fungi, and plant extracts, showing that biogenic synthesis is an economically feasible, simple and non-polluting process. Applications for biogenic copper nanoparticles are also discussed.

  8. High adherence copper plating process

    DOEpatents

    Nignardot, Henry

    1993-01-01

    A process for applying copper to a substrate of aluminum or steel by electrodeposition and for preparing an aluminum or steel substrate for electrodeposition of copper. Practice of the invention provides good adhesion of the copper layer to the substrate.

  9. Copper-containing zeolite catalysts

    DOEpatents

    Price, Geoffrey L.; Kanazirev, Vladislav

    1996-01-01

    A catalyst useful in the conversion of nitrogen oxides or in the synthesis of nitriles or imines from amines, formed by preparing an intimate mechanical mixture of a copper (II)-containing species, such as CuO or CuCl.sub.2, or elemental copper, with a zeolite having a pore mouth comprising 10 oxygen atoms, such as ZSM-5, converting the elemental copper or copper (II) to copper (I), and driving the copper (I) into the zeolite.

  10. Copper-containing zeolite catalysts

    DOEpatents

    Price, G.L.; Kanazirev, V.

    1996-12-10

    A catalyst useful in the conversion of nitrogen oxides or in the synthesis of nitriles or imines from amines, is formed by preparing an intimate mechanical mixture of a copper (II)-containing species, such as CuO or CuCl{sub 2}, or elemental copper, with a zeolite having a pore mouth comprising 10 oxygen atoms, such as ZSM-5, converting the elemental copper or copper (II) to copper (I), and driving the copper (I) into the zeolite.

  11. Improved Electroformed Structural Copper and Copper Alloys

    NASA Technical Reports Server (NTRS)

    Malone, G. A.; Hudson, W.; Babcock, B.; Edwards, R.

    1998-01-01

    Electroforming offers a superior means for fabricating internally cooled heat exchangers and structures subjected to thermal environments. Copper is deposited from many such applications because of the good thermal conductivity. It suffers from mediocre yield strength as a structural material and loses mechanical strength at intermediate temperatures. Mechanical properties similar to those of electroformed nickel are desired. Phase 1 examined innovative means to improve deposited copper structural performance. Yield strengths as high as 483 MPa (70 ksi) were obtained with useful ductility while retaining a high level of purity essential to good thermal conductivity. Phase 2 represents a program to explore new additive combinations in copper electrolytes to produce a more fine, equiaxed grain which can be thermally stabilized by other techniques such as alloying in modest degrees and dispersion strengthening. Evaluation of new technology - such as the codeposition of fullerness (diamond-like) particles were made to enhance thermal conductivity in low alloys. A test fire quality tube-bundle engine was fabricated using these copper property improvement concepts to show the superiority of the new coppers and fabrications methods over competitive technologies such as brazing and plasma deposition.

  12. COPPER RESEARCH UPDATE

    EPA Science Inventory

    This presentation provides an update and overview of new research results and remaining research needs with respect to copper corrosion control issues. The topics to be covered include: occurrence of elevated copper release in systems that meet the Action Level; impact of water c...

  13. Green Luminescent Copper Nanoparticles

    NASA Astrophysics Data System (ADS)

    Suresh, Y.; Annapurna, S.; Bhikshamaiah, G.; Singh, A. K.

    2016-09-01

    Copper nanoparticles are synthesized by a green chemical reduction method using Gum Kondagogu extract as stabilizer. The as-prepared powder samples are characterized by Transmission Electron Microscopy (TEM), Small Angle X-Ray Scattering (SAXS), UV-Visible Spectroscopy, X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) techniques. The as-prepared copper nanoparticles are found to be FCC crystalline and nearly monodispersed with particles size 19 nm. Photoluminescence (PL) measurement showed strong green visible emission and PL intensity was found enhanced with the presence of natural extract on copper nanoparticle surface. The increase in the PL intensity was mainly due to copper nanoparticles. Photoluminescence spectra of copper nanoparticles show an emission peak at 430 nm when illuminated at 325 nm.

  14. Synthesis, structures and DFT calculations of 2-(4,6-dimethyl pyrimidyl)selenolate complexes of Cu(I), Ag(I) and Au(I) and their conversion into metal selenide nanocrystals.

    PubMed

    Sharma, Rakesh K; Wadawale, Amey; Kedarnath, G; Manna, Debashree; Ghanty, Tapan K; Vishwanadh, B; Jain, Vimal K

    2014-05-07

    The complexes [M{SeC4H(Me-4,6)2N2}]6 (M = Cu (1), Ag (2)) and [Au{SeC4H(Me-4,6)2N2}(PEt3)] (3) have been prepared and characterized by elemental analyses, UV-vis, NMR ((1)H, (13)C, (77)Se) spectroscopy and single crystal X-ray diffraction. The crystal structures of [Cu{SeC4H(Me-4,6)2N2}]6·H2O (1·H2O), [Ag{SeC4H(Me-4,6)2N2}]6·6MeOH·H2O (2·6MeOH·H2O) and [Au{SeC4H(Me-4,6)2N2}(PEt3)] (3) revealed that their metal centers acquire distorted square-pyramidal, trigonal and linear geometries, respectively. DFT calculations have been carried out to rationalize nuclearity in copper(i) chalcogenolate complexes. The calculations suggest that there is hardly any energy difference between the tetrameric and hexameric forms. Thermal behavior of [Cu{SeC4H(Me-4,6)2N2}]6 was studied by thermogravimetric analysis. Thermolysis of [M{SeC4H(Me-4,6)2N2}]6 (M = Cu, Ag) in 1-dodecanethiol (DDT) at 150 °C gave a cubic phase of Cu7Se4 and an orthorhombic phase of Ag2Se, respectively. Copper selenide (Cu7Se4) thin films were deposited on glass and silicon substrates by using [Cu{SeC4H(Me-4,6)2N2}]6 at 400 °C by AACVD.

  15. Bioaccessibility and Solubility of Copper in Copper-Treated Lumber

    EPA Science Inventory

    Micronized copper (MC)-treated lumber is a recent replacement for Chromated Copper Arsenate (CCA) and Ammonium Copper (AC)-treated lumbers; though little is known about the potential risk of copper (Cu) exposure from incidental ingestion of MC-treated wood. The bioaccessibility o...

  16. Killing of bacteria by copper surfaces involves dissolved copper.

    PubMed

    Molteni, Cristina; Abicht, Helge K; Solioz, Marc

    2010-06-01

    Bacteria are rapidly killed on copper surfaces. However, the mechanism of this process remains unclear. Using Enterococcus hirae, the effect of inactivation of copper homeostatic genes and of medium compositions on survival and copper dissolution was tested. The results support a role for dissolved copper ions in killing.

  17. Simultaneous photoreductive removal of copper (II) and selenium (IV) under visible light over spherical binary oxide photocatalyst.

    PubMed

    Aman, Noor; Mishra, T; Hait, J; Jana, R K

    2011-02-15

    Waste water of copper mines and copper processing plant contains both copper and selenium ions with other contaminants. In this paper simultaneous photoreductive removal of copper (II) and selenium (IV) is studied for the first time using spherical binary oxide photocatalysts under visible light. All the synthesized materials are found to be mesoporous in nature with reasonably high surface area. Among a range of hole scavengers, only EDTA (ethylene diamine tetraacetic acid) and formic acid are found to be the most active for the reduction reaction. A comparative study is carried out using both the hole scavengers varying reaction time, concentration, pH etc. For a single contaminant, EDTA is found to be the best for Cu(II) reduction whereas formic acid is the best for Se(IV) reduction. In a mixed solution both EDTA and formic acid perform very well under visible light irradiation. Highest photocatalytic reduction in a mixed solution is observed at pH 3. Among all the synthesized materials, TiZr-10 performs as the best photocatalyst for both Cu(II) and Se(IV) reduction. However under UV light, Degussa P25 performs slightly better than TiZr-10. Present study shows that 100 ppm of mixed solution can be removed under visible light in 40 min of reaction using TiZr-10 as catalyst. Photodeposited material is found to be copper selenide rather than pure copper and selenium metal. This indicates that the waste water containing copper and selenium ions can be efficiently treated under visible or solar light.

  18. Development of new layered selenide oxides with perovskite-type oxide layers

    NASA Astrophysics Data System (ADS)

    Ushiyama, Koichi; Ogino, Hiraku; Kishio, Kohji; Shimoyama, Jun-Ichi

    2010-03-01

    Several Fe-based superconductors with perovskite-type oxide layers, such as Sr2ScFePO3 (Tc ˜ 17 K)^[1], were discovered in our previous study. These compounds are composed of alternate stacking of superconducting layers with antifluorite structure and perovskite-type blocking layers. Since both layers are flexible in terms of chemical composition, development of various new functional materials can be expected from this family. In the present study, we have attempted to synthesize new layered selenide oxides with CuSe layers and discovered more than ten compounds, such as Sr2MCu2Se2O2 (M = Mn, Co, Ni, Cu, Zn) and Sr2MCuSeO3 (M = Sc, Cr, Mn, Fe, Ga, In), thus far. These indicated that the CuSe layer can accommodate various types of blocking layers, which may lead various functions. Among them, Sr2Cu3Se2O2 has a potential as for the mother compound of superconductor, if appropriate concentration of carrier is introduced to the CuO2 layer. Crystal structure and physical properties of these newly found compounds will be reported. [1] H. Ogino et al., Supercond. Sci. Technol. 22 (2009) 075008

  19. Ultra-weak interlayer coupling in two-dimensional gallium selenide.

    PubMed

    Longuinhos, R; Ribeiro-Soares, J

    2016-09-14

    Beyond-graphene two-dimensional (2D) materials are envisioned as the future technology for optoelectronics, and the study of group IIIA metal monochalcogenides (GIIIAMMs) in 2D form is an emerging research field. Bulk gallium selenide (GaSe) is a layered material of this family which is widely used in nonlinear optics and is promising as a lubricant. The interlayer coupling in few-layer GaSe is currently unknown, and the stability of different polytypes is unclear. Here we use symmetry arguments and first-principles calculations to investigate the phase stability, interlayer coupling, and the Raman and infrared activity of the low-frequency shear and breathing modes expected in few-layer GaSe. Strategies to distinguish the number of layers and the β and ε polytypes are discussed. These symmetry results are valid for other isostructural few-layer GIIIAMM materials. Most importantly, by using a linear chain model, we show that the shear and breathing force constants reveal an ultra-weak interlayer coupling at the nanoscale in GaSe. These results suggest that β and ε few-layer GaSe show similar lubricant properties to those observed for few-layer graphite. Our analysis opens new perspectives about the study of interlayer interactions and their role in the mechanical and electrical properties of these new 2D materials.

  20. Independent Composition and Size Control for Highly Luminescent Indium-Rich Silver Indium Selenide Nanocrystals.

    PubMed

    Yarema, Olesya; Yarema, Maksym; Bozyigit, Deniz; Lin, Weyde M M; Wood, Vanessa

    2015-11-24

    Ternary I-III-VI nanocrystals, such as silver indium selenide (AISe), are candidates to replace cadmium- and lead-based chalcogenide nanocrystals as efficient emitters in the visible and near IR, but, due to challenges in controlling the reactivities of the group I and III cations during synthesis, full compositional and size-dependent behavior of I-III-VI nanocrystals is not yet explored. We report an amide-promoted synthesis of AISe nanocrystals that enables independent control over nanocrystal size and composition. By systematically varying reaction time, amide concentration, and Ag- and In-precursor concentrations, we develop a predictive model for the synthesis and show that AISe sizes can be tuned from 2.4 to 6.8 nm across a broad range of indium-rich compositions from AgIn11Se17 to AgInSe2. We perform structural and optical characterization for representative AISe compositions (Ag0.85In1.05Se2, Ag3In5Se9, AgIn3Se5, and AgIn11Se17) and relate the peaks in quantum yield to stoichiometries exhibiting defect ordering in the bulk. We optimize luminescence properties to achieve a record quantum yield of 73%. Finally, time-resolved photoluminescence measurements enable us to better understand the physics of donor-acceptor emission and the role of structure and composition in luminescence.

  1. Noncentrosymmetric selenide Ba4Ga4GeSe12: Synthesis, structure, and optical properties

    NASA Astrophysics Data System (ADS)

    Yin, Wenlong; Iyer, Abishek K.; Li, Chao; Lin, Xinsong; Yao, Jiyong; Mar, Arthur

    2016-09-01

    The selenide Ba4Ga4GeSe12, synthesized by reaction of BaSe, Ga2Se3, and GeSe2 at 1173 K, adopts a noncentrosymmetric tetragonal structure (space group P 4 bar21 c , Z=2, a=13.5468(4) Å, c=6.4915(2) Å) consisting of a three-dimensional network built from two types of corner-sharing MSe4 tetrahedra, with Ba cations occupying the intervening voids. It is isostructural to Pb4Ga4GeS12, Pb4Ga4GeSe12, and Ba4Ga4SnSe12, but differs subtly in site ordering. Structural refinements and bond valence sum analysis suggest partial disorder manifested by mixing of 0.75 Ga and 0.25 Ge within one tetrahedral site, and occupation of exclusively Ga within the other tetrahedral site. The optical band gap of 2.18(2) eV, measured from the UV/VIS/NIR diffuse reflectance spectrum, agrees with a calculated gap of 2.35 eV between valence and conduction bands and is consistent with the orange-yellow color of the crystals. Nonlinear optical measurements on powder samples revealed a weak second harmonic generation signal using 2.09 μm as the fundamental laser wavelength.

  2. Nanotexturing To Enhance Photoluminescent Response of Atomically Thin Indium Selenide with Highly Tunable Band Gap.

    PubMed

    Brotons-Gisbert, Mauro; Andres-Penares, Daniel; Suh, Joonki; Hidalgo, Francisco; Abargues, Rafael; Rodríguez-Cantó, Pedro J; Segura, Alfredo; Cros, Ana; Tobias, Gerard; Canadell, Enric; Ordejón, Pablo; Wu, Junqiao; Martínez-Pastor, Juan P; Sánchez-Royo, Juan F

    2016-05-11

    Manipulating properties of matter at the nanoscale is the essence of nanotechnology, which has enabled the realization of quantum dots, nanotubes, metamaterials, and two-dimensional materials with tailored electronic and optical properties. Two-dimensional semiconductors have revealed promising perspectives in nanotechnology. However, the tunability of their physical properties is challenging for semiconductors studied until now. Here we show the ability of morphological manipulation strategies, such as nanotexturing or, at the limit, important surface roughness, to enhance light absorption and the luminescent response of atomically thin indium selenide nanosheets. Besides, quantum-size confinement effects make this two-dimensional semiconductor to exhibit one of the largest band gap tunability ranges observed in a two-dimensional semiconductor: from infrared, in bulk material, to visible wavelengths, at the single layer. These results are relevant for the design of new optoelectronic devices, including heterostructures of two-dimensional materials with optimized band gap functionalities and in-plane heterojunctions with minimal junction defect density.

  3. Development of bismuth tellurium selenide nanoparticles for thermoelectric applications via a chemical synthetic process

    SciTech Connect

    Kim, Cham; Kim, Dong Hwan; Han, Yoon Soo; Chung, Jong Shik; Park, SangHa; Park, Soonheum; Kim, Hoyoung

    2011-03-15

    Research highlights: {yields} We synthesized a Bi{sub 2}Te{sub y}Se{sub 3-y} nano-compound via a chemical synthetic process. {yields} The compound was sintered to achieve an average grain size of about 300 nm. {yields} The resulting sintered body showed very low thermal conductivity. It is likely caused by the vigorous phonon scattering of the nano-sized grains. -- Abstract: Bismuth tellurium selenide (Bi{sub 2}Te{sub y}Se{sub 3-y}) nanoparticles for thermoelectric applications are successfully prepared via a water-based chemical reaction under atmospheric conditions. The nanostructured compound is prepared using a complexing agent (ethylenediaminetetraacetic acid) and a reducing agent (ascorbic acid) to stabilize the bismuth precursor (Bi(NO{sub 3}){sub 3}) in water and to favor the reaction with reduced sources of tellurium and selenium. The resulting powder is smaller than ca. 100 nm and has a crystalline structure corresponding to the rhombohedral Bi{sub 2}Te{sub 2.7}Se{sub 0.3}. The nanocrystalline powder is sintered via a spark plasma sintering process to obtain a sintered body composed of nano-sized grains. Important transport properties of the sintered body are measured to calculate its most important characteristic, the thermoelectric performance. The results demonstrate a relationship between the nanostructure of the sintered body and its thermal conductivity.

  4. Ultrafast Charge- and Energy-Transfer Dynamics in Conjugated Polymer: Cadmium Selenide Nanocrystal Blends

    PubMed Central

    2014-01-01

    Hybrid nanocrystal–polymer systems are promising candidates for photovoltaic applications, but the processes controlling charge generation are poorly understood. Here, we disentangle the energy- and charge-transfer processes occurring in a model system based on blends of cadmium selenide nanocrystals (CdSe-NC) with poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV) using a combination of time-resolved absorption and luminescence measurements. The use of different capping ligands (n-butylamine, oleic acid) as well as thermal annealing allows tuning of the polymer–nanocrystal interaction. We demonstrate that energy transfer from MDMO-PPV to CdSe-NCs is the dominant exciton quenching mechanism in nonannealed blends and occurs on ultrafast time scales (<1 ps). Upon thermal annealing electron transfer becomes competitive with energy transfer, with a transfer rate of 800 fs independent of the choice of the ligand. Interestingly, we find hole transfer to be much less efficient than electron transfer and to extend over several nanoseconds. Our results emphasize the importance of tuning the organic–nanocrystal interaction to achieve efficient charge separation and highlight the unfavorable hole-transfer dynamics in these blends. PMID:24490650

  5. Transition-metal doped sulfide, selenide, and telluride laser crystal and lasers

    DOEpatents

    Krupke, William F.; Page, Ralph H.; DeLoach, Laura D.; Payne, Stephen A.

    1996-01-01

    A new class of solid state laser crystals and lasers are formed of transition metal doped sulfide, selenide, and telluride host crystals which have four fold coordinated substitutional sites. The host crystals include II-VI compounds. The host crystal is doped with a transition metal laser ion, e.g., chromium, cobalt or iron. In particular, Cr.sup.2+ -doped ZnS and ZnSe generate laser action near 2.3 .mu.m. Oxide, chloride, fluoride, bromide and iodide crystals with similar structures can also be used. Important aspects of these laser materials are the tetrahedral site symmetry of the host crystal, low excited state absorption losses and high luminescence efficiency, and the d.sup.4 and d.sup.6 electronic configurations of the transition metal ions. The same materials are also useful as saturable absorbers for passive Q-switching applications. The laser materials can be used as gain media in amplifiers and oscillators; these gain media can be incorporated into waveguides and semiconductor lasers.

  6. Transition-metal doped sulfide, selenide, and telluride laser crystal and lasers

    DOEpatents

    Krupke, W.F.; Page, R.H.; DeLoach, L.D.; Payne, S.A.

    1996-07-30

    A new class of solid state laser crystals and lasers are formed of transition metal doped sulfide, selenide, and telluride host crystals which have four fold coordinated substitutional sites. The host crystals include II-VI compounds. The host crystal is doped with a transition metal laser ion, e.g., chromium, cobalt or iron. In particular, Cr{sup 2+}-doped ZnS and ZnSe generate laser action near 2.3 {micro}m. Oxide, chloride, fluoride, bromide and iodide crystals with similar structures can also be used. Important aspects of these laser materials are the tetrahedral site symmetry of the host crystal, low excited state absorption losses and high luminescence efficiency, and the d{sup 4} and d{sup 6} electronic configurations of the transition metal ions. The same materials are also useful as saturable absorbers for passive Q-switching applications. The laser materials can be used as gain media in amplifiers and oscillators; these gain media can be incorporated into waveguides and semiconductor lasers. 18 figs.

  7. Revealing the preferred interlayer orientations and stackings of two-dimensional bilayer gallium selenide crystals

    DOE PAGES

    Li, Xufan; Basile Carrasco, Leonardo A.; Yoon, Mina; ...

    2015-01-21

    Characterizing and controlling the interlayer orientations and stacking order of bilayer two-dimensional (2D) crystals and van der Waals (vdW) heterostructure is crucial to optimize their electrical and optoelectronic properties. The four polymorphs of layered gallium selenide (GaSe) that result from different layer stacking provide an ideal platform to study the stacking configurations in bilayer 2D crystals. Here, through a controllable vapor-phase deposition method we selectively grow bilayer GaSe crystals and investigate their two preferred 0° or 60° interlayer rotations. The commensurate stacking configurations (AA' and AB-stacking) in as-grown 2D bilayer GaSe crystals are clearly observed at the atomic scale andmore » the Ga-terminated edge structure are identified for the first time by using atomic-resolution scanning transmission electron microscopy (STEM). Theoretical analysis of the interlayer coupling energetics vs. interlayer rotation angle reveals that the experimentally-observed orientations are energetically preferred among the bilayer GaSe crystal polytypes. Here, the combined experimental and theoretical characterization of the GaSe bilayers afforded by these growth studies provide a pathway to reveal the atomistic relationships in interlayer orientations responsible for the electronic and optical properties of bilayer 2D crystals and vdW heterostructures.« less

  8. Multifunctional Bismuth Selenide Nanocomposites for Antitumor Thermo-Chemotherapy and Imaging.

    PubMed

    Li, Zhenglin; Hu, Ying; Howard, Kenneth A; Jiang, Tingting; Fan, Xuelei; Miao, Zhaohua; Sun, Ye; Besenbacher, Flemming; Yu, Miao

    2016-01-26

    To integrate real-time monitoring and therapeutic functions into a single nanoagent, we have designed and synthesized a drug-delivery platform based on a polydopamine(PDA)/human serum albumin (HSA)/doxorubicin (DOX) coated bismuth selenide (Bi2Se3) nanoparticle (NP). The resultant product exhibits high stability and biocompatibility both in vitro and in vivo. In addition to the excellent capability for both X-ray computed tomography (CT) and infrared thermal imaging, the NPs possess strong near-infrared (NIR) absorbance, and high capability and stability of photothermal conversion for efficient photothermal therapy (PTT) applications. Furthermore, a bimodal on-demand pH/photothermal-sensitive drug release has been achieved, resulting in a significant chemotherapeutic effect. Most importantly, the tumor-growth inhibition ratio achieved from thermo-chemotherapy of the Bi2Se3@PDA/DOX/HSA NPs was 92.6%, in comparison to the chemotherapy (27.8%) or PTT (73.6%) alone, showing a superior synergistic therapeutic effect. In addition, there is no noticeable toxicity induced by the NPs in vivo. This multifunctional platform is, therefore, promising for effective, safe and precise antitumor treatment and may stimulate interest in further exploration of drug loading on Bi2Se3 and other competent PTT agents combined with in situ imaging for biomedical applications.

  9. Tubular kidney damage and centrilobular liver injury after intratracheal instillation of dimethyl selenide.

    PubMed

    Cherdwongcharoensuk, Duangrudee; Henrique, Rui; Upatham, Suchart; Pereira, António Sousa; Aguas, Artur P

    2005-01-01

    Accidental inhalation of selenium (Se) derivatives, such as dimethyl selenide (DMSe), has been associated with damage of respiratory tissues. However, systemic effects of inhaled Se have not been thoroughly established. We have investigated whether mouse kidney and liver show cellular pathology as a result of a single intratracheal instillation of two different doses of DMSe (0.05 and 0.1 mg Se/kg BW). The animals were sacrificed 1, 7, 14, and 28 days after either 1 of the 2 DMSe treatments; samples were studied by light microscopy. Instillation of the low DMSe dose resulted in acute and transient tubular disease of the kidney expressed by swelling and vacuolation of epithelial cells of proximal tubules; in some mice, tubular necrosis was observed. After 14 days of the DMSe treatment, these lesions were ameliorated and, by day 28, the kidney tubular epithelium depicted a normal morphology. The same low dose of DMSe caused sustained damage to centrilobular hepatocytes characterized by swollen and vacuolized liver cells. After the instillation of the high DMSe dose, the mice presented sustained liver and kidney focal necrosis. Our data suggest that inhalation of DMSe results in: (i) acute tubular injury of the kidney and damage to centrilobular liver cells and (ii) this systemic pathology induced by DMSe is a dose-dependent phenomenon.

  10. Changes in bronchoalveolar lavage cells after intratracheal instillation of dimethyl selenide in mice.

    PubMed

    Cherdwongcharoensuk, Duangrudee; Upatham, Suchart; Oliveira, José Carlos; Sousa Pereira, António; AGuas, Artur P

    2004-01-01

    CD-1 mice were exposed to a single intratracheal instillation of either 0.025 or 0.075 mg Se/kg wt of dimethyl selenide (DMSe). They were studied over 4 weeks to define the cellular inflammatory response of the airways to DMSe. Bronchoalveolar (BAL) lavage was used to collect the DMSe-induced inflammatory exudates. The DMSe instillation resulted in phlogistic responses that had the neutrophil as the main leukocyte; they were present in BAL samples, mostly at days 1 and 7. Macrophages were also increased during DMSe-induced inflammation. The lower DMSe dose resulted in an inflammatory reaction lasting for 2 weeks. Mice treated with the higher DMSe dose still showed elevated numbers of neutrophils and macrophages 4 weeks after instillation. DMSe did not change the number of lymphocytes harvested from the airways. An early increase in total protein of BAL, and late enhancement in lactate dehydrogenase was observed in mice treated with the high DMSe dose. We conclude that inhalation of DMSe triggers a moderate and dose-dependent inflammatory reaction in the mouse airways, and that this phlogistic reaction is likely to participate in the damage of respiratory epithelia that occurs upon DMSe inhalation.

  11. A transparent nickel selenide counter electrode for high efficient dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Dong, Jia; Wu, Jihuai; Jia, Jinbiao; Ge, Jinhua; Bao, Quanlin; Wang, Chaotao; Fan, Leqing

    2017-04-01

    Nickel selenide (Ni0.85Se) was synthesized by a facile one-step hydrothermal reaction and Ni0.85Se film was prepared by spin-coating Ni0.85Se ink on FTO and used as counter electrode (CE) in dye-sensitized solar cells (DSSC). The Ni0.85Se CEs not only show high transmittance in visible range, but also possess remarkable electrocatalytic activity toward I-/I3-. The electrocatalytic ability of Ni0.85Se films was verified by cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization curves. The DSSC using Ni0.85Se CE exhibits a power conversion efficiency (PCE) of 8.96%, while the DSSC consisting of sputtered Pt CE only exhibits a PCE of 8.15%. When adding a mirror under Ni0.85Se CE, the resultant DSSC exhibits a PCE of 10.76%, which exceeds that of a DSSC based on sputtered Pt CE (8.44%) by 27.49%.

  12. Effect of aluminum and tellurium tetrachloride addition on the loss of arsenic selenide optical fiber

    NASA Astrophysics Data System (ADS)

    Nguyen, Vinh Q.; Drake, Gryphon; Villalobos, Guillermo; Gibson, Daniel; Bayya, Shyam; Kim, Woohong; Baker, Colin; Chin, Geoff; Kung, Frederic H.; Kotov, Mikhail I.; Busse, Lynda; Sanghera, Jasbinder S.

    2017-02-01

    Arsenic selenide glass optical fibers typically possess extrinsic absorption bands in the infrared wavelength regions associated with residual hydrogen and oxygen related impurities, despite using 6N purified elemental precursors. Consequently, special additives and refined processing steps are utilized in an attempt to reduce these and other impurities. We investigate the formation of particulate impurities during a purification process based on the addition of 0.1 wt% elemental aluminum (Al) and 0.2 wt% tellurium tetrachloride (TeCl4) during glass synthesis. It was found that during purification and melting steps, Al reacts with TeCl4 to form AlCl3, which in turn reacts with oxygen and hydrogen impurities and the fused quartz (SiO2) ampoule to produce HCl and stable submicron Al2SiO5 compounds in the As-Se glass and fibers. The intensity of the H-Se absorption band centered at 4.57 μm has been significantly reduced from 18 dB/m to 0.8 dB/m. Using thermodynamic data, we have identified stable Al2SiO5 submicron inclusions in the glass and fibers. A two-step gettering process is proposed as a solution to eliminating these inclusions.

  13. Structural and optical characterizations of chemically deposited cadmium selenide thin films

    SciTech Connect

    Khomane, A.S.

    2011-10-15

    Highlights: {yields} CdSe thin films deposited first time using formic acid as a complexing agent. {yields} The deposited thin films were characterized by XRD, SEM, UV-vis-NIR and electrical techniques. {yields} X-ray diffraction analysis shows presence of zinc blende crystal structure. -- Abstract: Synthesis of cadmium selenide thin films by CBD method has been presented. The deposited film samples were subjected to XRD, SEM, UV-vis-NIR and TEP characterization. X-ray diffraction analysis showed that CdSe film sample crystallized in zinc blende or cubic phase structure. SEM studies reveal that the grains are spherical in shape and uniformly distributed all over the surface of the substrates. The optical band gap energy of as deposited film sample was found to be in the order of 1.8 eV. The electrical conductivity of the film sample was found to be 10{sup -6} ({Omega} cm){sup -1} with n-type of conduction mechanism.

  14. 20 micros photocurrent response from lithographically patterned nanocrystalline cadmium selenide nanowires.

    PubMed

    Kung, Sheng-Chin; van der Veer, Wytze E; Yang, Fan; Donavan, Keith C; Penner, Reginald M

    2010-04-14

    Lithographically patterned nanowire electrodeposition (LPNE) provides a method for patterning nanowires composed of nanocrystalline cadmium selenide (nc-CdSe) over wafer-scale areas. We assess the properties of (nc-CdSe) nanowires for detecting light as photoconductors. Structural characterization of these nanowires by X-ray diffraction and transmission electron microscopy reveals they are composed of stoichiometric, single phase, cubic CdSe with a mean grain diameter of 10 nm. For nc-CdSe nanowires with lengths of many millimeters, the width and height dimensions could be varied over the range from 60 to 350 nm (w) and 20 to 80 nm (h). Optical absorption and photoluminescence spectra for nc-CdSe nanowires were both dominated by band-edge transitions. The photoconductivity properties of nc-CdSe nanowire arrays containing approximately 350 nanowires were evaluated by electrically isolating 5 microm nanowire lengths using evaporated gold electrodes. Photocurrents, i(photo), of 10-100 x (i(dark)) were observed with a spectral response characterized by an onset at 1.75 eV. i(photo) response and recovery times were virtually identical and in the range from 20 to 40 micros for 60 x 200 nm nanowires.

  15. Tunable photoconduction sensitivity and bandwidth for lithographically patterned nanocrystalline cadmium selenide nanowires.

    PubMed

    Kung, Sheng-Chin; Xing, Wendong; van der Veer, Wytze E; Yang, Fan; Donavan, Keith C; Cheng, Ming; Hemminger, John C; Penner, Reginald M

    2011-09-27

    Nanocrystalline cadmium selenide (nc-CdSe) nanowires were prepared using the lithographically patterned nanowire electrodeposition method. Arrays of 350 linear nc-CdSe nanowires with lateral dimensions of 60 nm (h) × 200 nm (w) were patterned at 5 μm pitch on glass. nc-CdSe nanowires electrodeposited from aqueous solutions at 25 °C had a mean grain diameter, d(ave), of 5 nm. A combination of three methods was used to increase d(ave) to 10, 20, and 100 nm: (1) The deposition bath was heated to 75 °C, (2) nanowires were thermally annealed at 300 °C, and (3) nanowires were exposed to methanolic CdCl(2) followed by thermal annealing at 300 °C. The morphology, chemical composition, grain diameter, and photoconductivity of the resulting nanowires were studied as a function of d(ave). As d(ave) was increased from 10 to 100 nm, the photoconductivity response of the nanowires was modified in two ways: First, the measured photoconductive gain, G, was elevated from G = 0.017 (d(ave) = 5 nm) to ∼4.9 (100 nm), a factor of 290. Second, the photocurrent rise time was increased from 8 μs for d(ave) = 10 nm to 8 s for 100 nm, corresponding to a decrease by a factor of 1 million of the photoconduction bandwidth from 44 kHz to 44 mHz.

  16. Photoluminescence properties of lead selenide produced by selenization and a solvothermal method.

    PubMed

    Kim, Jungdong; Ahn, Hak-Young; Kim, Seung Gi; Oh, Eunsoon; Ju, Byeong-Kwon; Choi, Won Jun; Cho, So-Hye

    2017-01-06

    We studied temperature-dependent photoluminescence (PL) spectra of lead selenide (PbSe) dendrites and cubes grown by a solvothermal method. Their PL peaks were located at ∼8 μm at 10 K with a full width at half maximum (FWHM) of 10 meV. Using the temperature-dependent FWHM values, we obtained carrier-phonon coupling coefficients for PbSe. We also demonstrated mechanochemical synthesis of polycrystalline PbS nanoparticles and their successful conversion into a PbSe layer composed of nanocrystals by a selenization process with thermal treatment. The nanocrystals were found to be formed by the orientation alignment of small grains in the process. The PL peak energies of the PbSe layers as well as the PbSe dendrites and the cubes agreed well with their absorption edges in the transmission spectra, indicating that the photoluminescence originates from the band-edge emission. The band-edge emissions hold promise for the development of potential mid-infrared light sources using PbSe fabricated by these methods.

  17. Growth of zinc selenide single crystals by physical vapor transport in microgravity

    NASA Technical Reports Server (NTRS)

    Rosenberger, Franz

    1993-01-01

    The goals of this research were the optimization of growth parameters for large (20 mm diameter and length) zinc selenide single crystals with low structural defect density, and the development of a 3-D numerical model for the transport rates to be expected in physical vapor transport under a given set of thermal and geometrical boundary conditions, in order to provide guidance for an advantageous conduct of the growth experiments. In the crystal growth studies, it was decided to exclusively apply the Effusive Ampoule PVT technique (EAPVT) to the growth of ZnSe. In this technique, the accumulation of transport-limiting gaseous components at the growing crystal is suppressed by continuous effusion to vacuum of part of the vapor contents. This is achieved through calibrated leaks in one of the ground joints of the ampoule. Regarding the PVT transport rates, a 3-D spectral code was modified. After introduction of the proper boundary conditions and subroutines for the composition-dependent transport properties, the code reproduced the experimentally determined transport rates for the two cases with strongest convective flux contributions to within the experimental and numerical error.

  18. Ba4Ga2Se8: A ternary selenide containing chains and discrete Se22- units

    NASA Astrophysics Data System (ADS)

    Yin, Wenlong; Iyer, Abishek K.; Lin, Xinsong; Mar, Arthur

    2016-05-01

    The ternary selenide Ba4Ga2Se8 has been synthesized by reaction of BaSe, Ga2Se3, and Se at 1023 K. Single-crystal X-ray diffraction analysis revealed a monoclinic structure (space group P21/c, Z=4, a=13.2393(5) Å, b=6.4305(2) Å, c=20.6432(8) Å, β=104.3148(6)°) featuring one-dimensional chains of corner-sharing Ga-centered tetrahedra and discrete Se22- anionic units, with charge-compensating Ba2+ cations located between them. The UV/vis/NIR diffuse reflectance spectrum reveals an optical band gap of 1.63(2) eV, which is consistent with the black color of the crystals and agrees with a calculated gap of 1.51 eV obtained from band structure calculations. The presence of the Se22- units narrows the band gap in Ba4Ga2Se8 relative to other Ba-Ga-Se phases.

  19. Revealing the preferred interlayer orientations and stackings of two-dimensional bilayer gallium selenide crystals

    SciTech Connect

    Li, Xufan; Basile Carrasco, Leonardo A.; Yoon, Mina; Ma, Cheng; Puretzky, Alexander A.; Lee, Jaekwang; Idrobo Tapia, Juan Carlos; Chi, Miaofang; Rouleau, Christopher M.; Geohegan, David B.; Xiao, Kai

    2015-01-21

    Characterizing and controlling the interlayer orientations and stacking order of bilayer two-dimensional (2D) crystals and van der Waals (vdW) heterostructure is crucial to optimize their electrical and optoelectronic properties. The four polymorphs of layered gallium selenide (GaSe) that result from different layer stacking provide an ideal platform to study the stacking configurations in bilayer 2D crystals. Here, through a controllable vapor-phase deposition method we selectively grow bilayer GaSe crystals and investigate their two preferred 0° or 60° interlayer rotations. The commensurate stacking configurations (AA' and AB-stacking) in as-grown 2D bilayer GaSe crystals are clearly observed at the atomic scale and the Ga-terminated edge structure are identified for the first time by using atomic-resolution scanning transmission electron microscopy (STEM). Theoretical analysis of the interlayer coupling energetics vs. interlayer rotation angle reveals that the experimentally-observed orientations are energetically preferred among the bilayer GaSe crystal polytypes. Here, the combined experimental and theoretical characterization of the GaSe bilayers afforded by these growth studies provide a pathway to reveal the atomistic relationships in interlayer orientations responsible for the electronic and optical properties of bilayer 2D crystals and vdW heterostructures.

  20. Photoluminescence properties of lead selenide produced by selenization and a solvothermal method

    NASA Astrophysics Data System (ADS)

    Kim, Jungdong; Ahn, Hak-Young; Kim, Seung Gi; Oh, Eunsoon; Ju, Byeong-Kwon; Choi, Won Jun; Cho, So-Hye

    2017-01-01

    We studied temperature-dependent photoluminescence (PL) spectra of lead selenide (PbSe) dendrites and cubes grown by a solvothermal method. Their PL peaks were located at ˜8 μm at 10 K with a full width at half maximum (FWHM) of 10 meV. Using the temperature-dependent FWHM values, we obtained carrier-phonon coupling coefficients for PbSe. We also demonstrated mechanochemical synthesis of polycrystalline PbS nanoparticles and their successful conversion into a PbSe layer composed of nanocrystals by a selenization process with thermal treatment. The nanocrystals were found to be formed by the orientation alignment of small grains in the process. The PL peak energies of the PbSe layers as well as the PbSe dendrites and the cubes agreed well with their absorption edges in the transmission spectra, indicating that the photoluminescence originates from the band-edge emission. The band-edge emissions hold promise for the development of potential mid-infrared light sources using PbSe fabricated by these methods.

  1. Quantum size confinement in gallium selenide nanosheets: band gap tunability versus stability limitation.

    PubMed

    Andres-Penares, Daniel; Cros, Ana; Martínez-Pastor, Juan P; Sánchez-Royo, Juan F

    2017-04-28

    Gallium selenide is one of the most promising candidates to extend the window of band gap values provided by existing two-dimensional semiconductors deep into the visible potentially reaching the ultraviolet. However, the tunability of its band gap by means of quantum confinement effects is still unknown, probably due to poor nanosheet stability. Here, we demonstrate that the optical band gap band of GaSe nanosheets can be tuned by ∼120 meV from bulk to 8 nm thick. The luminescent response of very thin nanosheets (<8 nm) is strongly quenched due to early oxidation. Oxidation favors the emergence of sharp material nanospikes at the surface attributable to strain relaxation. Simultaneously, incorporated oxygen progressively replaces selenium giving rise to Ga2O3, with a residual presence of Ga2Se3 that tends to desorb. These results are relevant for the development and design of visible/ultraviolet electronics and optoelectronics with tunable functionalities based on atomically thin GaSe.

  2. Topological insulator bismuth selenide as a theranostic platform for simultaneous cancer imaging and therapy

    NASA Astrophysics Data System (ADS)

    Li, Juan; Jiang, Fei; Yang, Bo; Song, Xiao-Rong; Liu, Yan; Yang, Huang-Hao; Cao, Dai-Rong; Shi, Wen-Rong; Chen, Guo-Nan

    2013-06-01

    Employing theranostic nanoparticles, which combine both therapeutic and diagnostic capabilities in one dose, has promise to propel the biomedical field toward personalized medicine. Here we investigate the theranostic properties of topological insulator bismuth selenide (Bi2Se3) in in vivo and in vitro system for the first time. We show that Bi2Se3 nanoplates can absorb near-infrared (NIR) laser light and effectively convert laser energy into heat. Such photothermal conversion property may be due to the unique physical properties of topological insulators. Furthermore, localized and irreversible photothermal ablation of tumors in the mouse model is successfully achieved by using Bi2Se3 nanoplates and NIR laser irradiation. In addition, we also demonstrate that Bi2Se3 nanoplates exhibit strong X-ray attenuation and can be utilized for enhanced X-ray computed tomography imaging of tumor tissue in vivo. This study highlights Bi2Se3 nanoplates could serve as a promising platform for cancer diagnosis and therapy.

  3. Memory functions of nanocrystalline cadmium selenide embedded ZrHfO high-k dielectric stack

    SciTech Connect

    Lin, Chi-Chou; Kuo, Yue

    2014-02-28

    Metal-oxide-semiconductor capacitors made of the nanocrystalline cadmium selenide nc-CdSe embedded Zr-doped HfO{sub 2} high-k stack on the p-type silicon wafer have been fabricated and studied for their charge trapping, detrapping, and retention characteristics. Both holes and electrons can be trapped to the nanocrystal-embedded dielectric stack depending on the polarity of the applied gate voltage. With the same magnitude of applied gate voltage, the sample can trap more holes than electrons. A small amount of holes are loosely trapped at the nc-CdSe/high-k interface and the remaining holes are strongly trapped to the bulk nanocrystalline CdSe site. Charges trapped to the nanocrystals caused the Coulomb blockade effect in the leakage current vs. voltage curve, which is not observed in the control sample. The addition of the nanocrystals to the dielectric film changed the defect density and the physical thickness, which are reflected on the leakage current and the breakdown voltage. More than half of the originally trapped holes can be retained in the embedded nanocrystals for more than 10 yr. The nanocrystalline CdSe embedded high-k stack is a useful gate dielectric for this nonvolatile memory device.

  4. Electrothermal atomic-absorption determination of silver in zinc and cadmium selenides

    SciTech Connect

    Khozhainov, Yu.M.; Dolova, N.K.

    1987-10-01

    An atomic-absorption signal is dependent on the chemical forms of the test element and matrix in the solution as well as on the processes during electrothermal atomization. The authors have examined the absorption due to silver with a Saturn-2 spectrophotometer with such atomization; the authors used the 328.1 nm line (i = 10 mA, slit width 0.15, time-constant 0.6 sec). The presence of cadmium and zinc was monitored from the 326.1 and 213.8 nm lines respectively. The measurements were made in argon. The internal gas flow was turned off during the atomization. The graphite was used until there were sharp changes in the silver absorption due to change in the structure of the graphite and occurrence of the memory effect. The results from over 100 specimens of cadmium selenide films analyzed for silver showed that the results were in full agreement with the conditions for silver activation (time, temperature, and activator mass).

  5. Synthesis and optoelectrical properties of f-graphene/cadmium selenide hybrid system

    NASA Astrophysics Data System (ADS)

    Babkair, Saeed Salem; Azam, Ameer; Singh, Kuldeep; Dhawan, Sundeep Kumar; Khan, Mohd Taukeer

    2015-01-01

    The present work demonstrates the synthesis of a hybrid accepter material containing amino-functionalized graphene oxide (GO) and an inorganic semiconducting material, cadmium selenide (CdSe). First, amino-functionalized graphene was synthesized and then nanocrystals (NCs) of CdSe were in situ grown in the functionalized-(GO) matrix named f-GCdSe. Structural studies such as x-ray diffraction, and a scanning electron microscopic were employed to investigate the growth of CdSe NCs in the graphene matrix. To understand the charge generation and transfer process at the donor/acceptor interface, the absorption, photoluminescence (PL), and transient absorption spectroscopic (TAS) studies have been carried out in poly(3-hexylthiophene) (P3HT)/f-GCdSe thin films. PL quenching in P3HT/f-GCdSe thin film suggests that charge transfer takes place at the donor/acceptor interface. TAS shows higher optical density and long lived free carriers for P3HT/f-GCdSe thin film. These results suggest that f-GCdSe is an excellent electron-acceptor material for organic photovoltaic devices.

  6. Bond thermal expansion and effective pair potential in crystals: the case of cadmium selenide.

    PubMed

    Sanson, Andrea

    2011-08-10

    The local dynamics of cadmium selenide (CdSe) with wurtzite structure has been investigated by molecular dynamics simulations, using a many-body Tersoff potential. The radial distribution functions (i.e., the effective pair potentials) of the first seven coordination shells have been determined as a function of temperature, as well as their parallel and perpendicular mean-square relative atomic displacements. The bond thermal expansion of the first coordination shell is mainly due to the asymmetry of the effective pair potential. In contrast, the bond thermal expansion of the outer shells is mostly due to a rigid shift of the effective pair potential. This behavior, recently observed also in simple cubic monoatomic crystals, can be generalized and related to the correlation of atomic motion. Finally, a shift toward lower values of the first Se-Cd effective pair potential has been observed when increasing the temperature, confirming previous findings by extended x-ray absorption fine-structure measurements. Differently from superionic conductors like AgI and CuBr, in which this anomalous negative shift was tentatively explained by cluster distortion and cation diffusion, the negative shift of CdSe is related to the peculiar properties of the crystalline potential.

  7. Photoluminescence properties of cadmium-selenide quantum dots embedded in a liquid-crystal polymer matrix

    SciTech Connect

    Tselikov, G. I. Timoshenko, V. Yu.; Plenge, J.; Ruehl, E.; Shatalova, A. M.; Shandryuk, G. A.; Merekalov, A. S.; Tal'roze, R. V.

    2013-05-15

    The photoluminescence properties of cadmium-selenide (CdSe) quantum dots with an average size of {approx}3 nm, embedded in a liquid-crystal polymer matrix are studied. It was found that an increase in the quantum-dot concentration results in modification of the intrinsic (exciton) photoluminescence spectrum in the range 500-600 nm and a nonmonotonic change in its intensity. Time-resolved measurements show the biexponential decay of the photoluminescence intensity with various ratios of fast and slow components depending on the quantum-dot concentration. In this case, the characteristic lifetimes of exciton photoluminescence are 5-10 and 35-50 ns for the fast and slow components, respectively, which is much shorter than the times for colloidal CdSe quantum dots of the same size. The observed features of the photoluminescence spectra and kinetics are explained by the effects of light reabsorption, energy transfer from quantum dots to the liquid-crystal polymer matrix, and the effect of the electronic states at the CdSe/(liquid crystal) interface.

  8. Ultrafast charge- and energy-transfer dynamics in conjugated polymer: cadmium selenide nanocrystal blends.

    PubMed

    Morgenstern, Frederik S F; Rao, Akshay; Böhm, Marcus L; Kist, René J P; Vaynzof, Yana; Greenham, Neil C

    2014-02-25

    Hybrid nanocrystal-polymer systems are promising candidates for photovoltaic applications, but the processes controlling charge generation are poorly understood. Here, we disentangle the energy- and charge-transfer processes occurring in a model system based on blends of cadmium selenide nanocrystals (CdSe-NC) with poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV) using a combination of time-resolved absorption and luminescence measurements. The use of different capping ligands (n-butylamine, oleic acid) as well as thermal annealing allows tuning of the polymer-nanocrystal interaction. We demonstrate that energy transfer from MDMO-PPV to CdSe-NCs is the dominant exciton quenching mechanism in nonannealed blends and occurs on ultrafast time scales (<1 ps). Upon thermal annealing electron transfer becomes competitive with energy transfer, with a transfer rate of 800 fs independent of the choice of the ligand. Interestingly, we find hole transfer to be much less efficient than electron transfer and to extend over several nanoseconds. Our results emphasize the importance of tuning the organic-nanocrystal interaction to achieve efficient charge separation and highlight the unfavorable hole-transfer dynamics in these blends.

  9. Efficient solution-processed small molecule: Cadmium selenide quantum dot bulk heterojunction solar cells

    SciTech Connect

    Gupta, Vinay; Upreti, Tanvi; Chand, Suresh

    2013-12-16

    We report bulk heterojunction solar cells based on blends of solution-processed small molecule [7,7′-(4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b′]dithiophene-2,6-diyl) bis(6-fluoro-4-(5′-hexyl-[2,2′-bithiophen]-5yl)benzo[c] [1,2,5] thiadiazole)] p-DTS(FBTTh{sub 2}){sub 2}: Cadmium Selenide (CdSe) (70:30, 60:40, 50:50, and 40:60) in the device configuration: Indium Tin Oxide /poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/p-DTS(FBTTh{sub 2}){sub 2}: CdSe/Ca/Al. The optimized ratio of p-DTS(FBTTh{sub 2}){sub 2}:CdSe::60:40 leads to a short circuit current density (J{sub sc}) = 5.45 mA/cm{sup 2}, open circuit voltage (V{sub oc}) = 0.727 V, and fill factor (FF) = 51%, and a power conversion efficiency = 2.02% at 100 mW/cm{sup 2} under AM1.5G illumination. The J{sub sc} and FF are sensitive to the ratio of p-DTS(FBTTh{sub 2}){sub 2}:CdSe, which is a crucial factor for the device performance.

  10. Biokinetics and in vivo distribution behaviours of silica-coated cadmium selenide quantum dots.

    PubMed

    Vibin, M; Vinayakan, R; John, Annie; Raji, V; Rejiya, C S; Abraham, Annie

    2011-08-01

    Recently, quantum dots derived from trace elements like cadmium and selenium have attracted widespread interest in biology and medicine. They are rapidly being used as novel tools for both diagnostic and therapeutic purposes. In this report, we evaluated the distribution of silica-coated cadmium selenide (CdSe) quantum dots (QDs) following intravenous injection into male Swiss albino mice as a model system for determining tissue localization using in vivo fluorescence and ex vivo elemental analysis by inductively coupled plasma optical emission spectroscopy (ICP-OES). Trioctylphosphine oxide-capped CdSe quantum dots were synthesized and rendered water soluble by overcoating with silica, using aminopropyl silane (APS) as silica precursor. ICP-OES was used to measure the cadmium content to indicate the concentration of QDs in blood, organs and excretion samples collected at predetermined time intervals. Meanwhile, the distribution and aggregation state of QDs in tissues were also investigated in cryosections of the organs by fluorescence microscopy. We have demonstrated that the liver and kidney were the main target organs for QDs. Our systematic investigation clearly shows that most of the QDs were metabolized in the liver and excreted via faeces and urine in vivo. A fraction of free QDs, maintaining their original form, could be filtered by glomerular capillaries and excreted via urine as small molecules within 5 days.

  11. Annealed single-crystal cadmium selenide electrodes in liquid junction solar cells

    SciTech Connect

    Wessel, S.; Colbow, K.; Mackintosh, A.

    1984-12-01

    I-V characteristics, voltage dependence of the quantum efficiency, and spectral response were compared for annealed single-crystal CdSe photoanodes. Annealing in cadmium atmosphere improved the overall solar response considerably, while annealing under vacuum revealed a poor response for photon energies larger than 1.8 eV and a high quantum efficiency for near-bandgap energies. This behavior may be attributed to electron-hole pai generation from interbandgap states and a large density of minority carrier recombination centers near the crystal surface, owing to a high nonstoichiometry and a selenium layer at the surface. Annealing in selenium atmosphere resulted in very poor solar response caused by compensation. Simultaneous illumination of the electrodes with a He-Ne lase strongly enhanced the quantum efficiency for vacuum-annealed crystals for near-bandgap photons. We attribute this to electron trapping in the selenium-rich surface, with a resulting increase in depletion-layer width in the cadmium selenide.

  12. Topological insulator bismuth selenide as a theranostic platform for simultaneous cancer imaging and therapy

    PubMed Central

    Li, Juan; Jiang, Fei; Yang, Bo; Song, Xiao-Rong; Liu, Yan; Yang, Huang-Hao; Cao, Dai-Rong; Shi, Wen-Rong; Chen, Guo-Nan

    2013-01-01

    Employing theranostic nanoparticles, which combine both therapeutic and diagnostic capabilities in one dose, has promise to propel the biomedical field toward personalized medicine. Here we investigate the theranostic properties of topological insulator bismuth selenide (Bi2Se3) in in vivo and in vitro system for the first time. We show that Bi2Se3 nanoplates can absorb near-infrared (NIR) laser light and effectively convert laser energy into heat. Such photothermal conversion property may be due to the unique physical properties of topological insulators. Furthermore, localized and irreversible photothermal ablation of tumors in the mouse model is successfully achieved by using Bi2Se3 nanoplates and NIR laser irradiation. In addition, we also demonstrate that Bi2Se3 nanoplates exhibit strong X-ray attenuation and can be utilized for enhanced X-ray computed tomography imaging of tumor tissue in vivo. This study highlights Bi2Se3 nanoplates could serve as a promising platform for cancer diagnosis and therapy. PMID:23770650

  13. Molecular beam epitaxy of 2D-layered gallium selenide on GaN substrates

    NASA Astrophysics Data System (ADS)

    Lee, Choong Hee; Krishnamoorthy, Sriram; O'Hara, Dante J.; Brenner, Mark R.; Johnson, Jared M.; Jamison, John S.; Myers, Roberto C.; Kawakami, Roland K.; Hwang, Jinwoo; Rajan, Siddharth

    2017-03-01

    Large area epitaxy of two-dimensional (2D) layered materials with high material quality is a crucial step in realizing novel device applications based on 2D materials. In this work, we report high-quality, crystalline, large-area gallium selenide (GaSe) films grown on bulk substrates such as c-plane sapphire and gallium nitride (GaN) using a valved cracker source for Se. (002)-Oriented GaSe with random in-plane orientation of domains was grown on sapphire and GaN substrates at a substrate temperature of 350-450 °C with complete surface coverage. Higher growth temperature (575 °C) resulted in the formation of single-crystalline ɛ-GaSe triangular domains with six-fold symmetry confirmed by in-situ reflection high electron energy diffraction and off-axis x-ray diffraction. A two-step growth method involving high temperature nucleation of single crystalline domains and low temperature growth to enhance coalescence was adopted to obtain continuous (002)-oriented GaSe with an epitaxial relationship with the substrate. While six-fold symmetry was maintained in the two step growth, β-GaSe phase was observed in addition to the dominant ɛ-GaSe in cross-sectional scanning transmission electron microscopy images. This work demonstrates the potential of growing high quality 2D-layered materials using molecular beam epitaxy and can be extended to the growth of other transition metal chalcogenides.

  14. Chemical deposition of bismuth selenide thin films using N,N-dimethylselenourea

    NASA Astrophysics Data System (ADS)

    García, V. M.; Nair, M. T. S.; Nair, P. K.; Zingaro, R. A.

    1997-05-01

    Good quality thin films of bismuth selenide of thickness up to 0268-1242/12/5/020/img7 were deposited from solutions containing bismuth nitrate, triethanolamine and N,N-dimethylselenourea maintained at temperatures ranging from room temperature to 0268-1242/12/5/020/img8. X-ray diffraction patterns of the samples annealed at 0268-1242/12/5/020/img9 in air match the standard pattern of hexagonal 0268-1242/12/5/020/img10 (paraguanajuatite, JCPDS 33-0214). The films exhibit strong optical absorption corresponding to a bandgap of about 1.7 - 1.41 eV in the as-prepared films. These values decrease to about 1.57 - 1.06 eV upon annealing the films at 0268-1242/12/5/020/img9 for 1 h in nitrogen. As-deposited, the films show high sheet resistance 0268-1242/12/5/020/img12 in the dark. Annealing the films in air or in nitrogen enhances the dark current by about seven orders of magnitude; the resulting dark conductivity is about 0268-1242/12/5/020/img13. This enhancement in conductivity results from improved crystallinity as well as from partial loss of selenium.

  15. Fabricating Copper Nanotubes by Electrodeposition

    NASA Technical Reports Server (NTRS)

    Yang, E. H.; Ramsey, Christopher; Bae, Youngsam; Choi, Daniel

    2009-01-01

    Copper tubes having diameters between about 100 and about 200 nm have been fabricated by electrodeposition of copper into the pores of alumina nanopore membranes. Copper nanotubes are under consideration as alternatives to copper nanorods and nanowires for applications involving thermal and/or electrical contacts, wherein the greater specific areas of nanotubes could afford lower effective thermal and/or electrical resistivities. Heretofore, copper nanorods and nanowires have been fabricated by a combination of electrodeposition and a conventional expensive lithographic process. The present electrodeposition-based process for fabricating copper nanotubes costs less and enables production of copper nanotubes at greater rate.

  16. DFT studies on structural properties and electron density topologies of the iron selenides Fe m Se n (1 ≤ m, n ≤ 4)

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Liu, Jianhong

    2016-12-01

    We report the structural properties and electron density topologies of the iron selenides Fe m Se n (1 ≤ m, n ≤ 4) using DFT method. Structural studies reveal the Se atom leads to significant change in the geometries of the iron selenides. We confirm that the bond length between Fe atoms increase owing to the sequential addition of Se atom. Comparable stabilities were investigated based on the variation of averaged binding energies and selenium doping energy. The covalent property of the Fe-Se bond is increased as the coincident bond critical points (BCPs) showed smaller positive nabla _{{ρ _{BCP}}}^2 values than those of original FeSe molecule. Our results demonstrate that the ρFe-Fe values keep in the order of 0.048-0.220 a.u. Almost all of the nabla _{{ρ _{BCP}}}^2 values are positive and consequently mean the closed-shell interactions are conserved in the iron selenides.

  17. Involvement of L-arginine-nitric oxide-cyclic guanosine monophosphate pathway in the antidepressant-like effect of bis selenide in the mouse tail suspension test.

    PubMed

    Jesse, Cristiano R; Wilhelm, Ethel A; Bortolatto, Cristiani F; Rocha, João B T; Nogueira, Cristina W

    2010-06-10

    The present study investigated a possible antidepressant-like effect of bis selenide by using the forced swimming and the tail suspension tests. The involvement of the l-arginine-nitric oxide-cyclic guanosine monophosphate signaling pathway in the antidepressant-like action of bis selenide was investigated. Bis selenide, given by oral route at doses of 0.5-5mg/kg, decreased the immobility time in the forced swimming and tail suspension tests. Pretreatment with l-arginine (750mg/kg, intraperitoneal, i.p., a nitric oxide precursor), sildenafil (5mg/kg, i.p., a phosphodiesterase 5 inhibitor) or S-nitroso-N-acetyl-penicillamine (25microg/site, intracerebroventricular, i.c.v., a nitric oxide donor) reversed the reduction in the immobility time elicited by bis selenide (1mg/kg, p.o.) in the tail suspension test. Bis selenide (0.1mg/kg, p.o., a subeffective dose) produced a synergistic antidepressant-like effect with N(G)-nitro-L-arginine (0.3mg/kg, i.p., an inhibitor of nitric oxide synthase) or 7-nitroindazole (25mg/kg, i.p., a specific neuronal nitric oxide synthase inhibitor) in the tail suspension test. Pretreatment of animals with methylene blue (10mg/kg, i.p., an inhibitor of nitric oxide synthase and soluble guanylate cyclase) or 1H-[1,2,4] oxadiazolo [4,3-a]quinoxalin-1-one (30pmol, i.c.v., a specific inhibitor of soluble guanylate cyclase), at subeffective doses, caused a synergistic effect with bis selenide in the tail suspension test. Bis selenide (1mg/kg, p.o.), at an effective dose in the forced swimming and tail suspension tests, caused a significant decrease in the mouse cerebral nitrate/nitrite levels. The antidepressant-like effect of bis selenide in the tail suspension test is dependent on the inhibition of the L-arginine-nitric oxide-cyclic guanosine monophosphate pathway.

  18. Micromachining with copper lasers

    NASA Astrophysics Data System (ADS)

    Knowles, Martyn R. H.; Bell, Andy; Foster-Turner, Gideon; Rutterford, Graham; Chudzicki, J.; Kearsley, Andrew J.

    1997-04-01

    In recent years the copper laser has undergone extensive development and has emerged as a leading and unique laser for micromachining. The copper laser is a high average power (10 - 250 W), high pulse repetition rate (2 - 32 kHz), visible laser (511 nm and 578 nm) that produces high peak power (typically 200 kW), short pulses (30 ns) and very good beam quality (diffraction limited). This unique set of laser parameters results in exceptional micro-machining in a wide variety of materials. Typical examples of the capabilities of the copper laser include the drilling of small holes (10 - 200 micrometer diameter) in materials as diverse as steel, ceramic, diamond and polyimide with micron precision and low taper (less than 1 degree) cutting and profiling of diamond. Application of the copper laser covers the electronic, aerospace, automotive, nuclear, medical and precision engineering industries.

  19. Volatility of copper

    SciTech Connect

    Palmer, D.A.; Simonson, J.M.; Joyce, D.B.

    1996-08-01

    The relevant aqueous thermodynamics of copper and its oxides are evaluated and summarized with emphasis on solubility, hydrolysis, and complexation. The solubilities of metallic copper, solid cuprous and cupric oxides in steam measured by Pocock and Stewart in 1963 are discussed and the latter data are fitted in the form of established empirical equations and compared to other existing results. No other sources of data were found for the solubility of copper and cupric oxide in steam and even these data are very limited. Discussion of corresponding available solubility data on both oxide phases in liquid water is given. The possible effects of complexing agents are considered. A brief discussion is provided of the role of surface adsorption in determining the fate of dissolved copper in the boiler. 37 refs., 5 figs., 3 tabs.

  20. Redox control of GPx catalytic activity through mediating self-assembly of Fmoc-phenylalanine selenide into switchable supramolecular architectures.

    PubMed

    Huang, Zupeng; Luo, Quan; Guan, Shuwen; Gao, Jianxiong; Wang, Yongguo; Zhang, Bo; Wang, Liang; Xu, Jiayun; Dong, Zeyuan; Liu, Junqiu

    2014-12-28

    Artificial enzymes capable of achieving tunable catalytic activity through stimuli control of enzymatic structure transition are of significance in biosensor and biomedicine research. Herein we report a novel smart glutathione peroxidise (GPx) mimic with modulatory catalytic activity based on redox-induced supramolecular self-assembly. First, an amphiphilic Fmoc-phenylalanine-based selenide was designed and synthesized, which can self-assemble into nanospheres (NSs) in aqueous solution. The NSs demonstrate extremely low GPx activity. Upon the oxidation of hydroperoxides (ROOH), the selenide can be quickly transformed into the selenoxide form. The change of the molecular structure induces complete morphology transition of the self-assemblies from NSs to nanotubes (NTs), resulting in great enhancement in the GPx catalytic activity. Under the reduction of GSH, the selenoxide can be further reversibly reduced back into the selenide; therefore the reversible switch between the NSs and NTs can be successfully accomplished. The relationship between the catalytic activity and enzymatic structure was also investigated. The dual response nature makes this mimic play roles of both a sensor and a GPx enzyme at the same time, which can auto-detect the signal of ROOH and then auto-change its activity to achieve quick or slow/no scavenging of ROOH. The dynamic balance of ROOH is vital in organisms, in which an appropriate amount of ROOH does benefit to the metabolism, whereas surplus ROOH can cause oxidative damage of the cell instead and this smart mimic is of remarkable significance. We expect that such a mimic can be developed into an effective antioxidant drug and provide a new platform for the construction of intelligent artificial enzymes with multiple desirable properties.

  1. Carbon-Coated Co(3+)-Rich Cobalt Selenide Derived from ZIF-67 for Efficient Electrochemical Water Oxidation.

    PubMed

    Li, Siwen; Peng, Sijia; Huang, Linsong; Cui, Xiaoqi; Al-Enizi, Abdullah M; Zheng, Gengfeng

    2016-08-17

    Oxygen evolution reaction (OER) electrocatalysts are confronted with challenges such as sluggish kinetics, low conductivity, and instability, restricting the development of water splitting. In this study, we report an efficient Co(3+)-rich cobalt selenide (Co0.85Se) nanoparticles coated with carbon shell as OER electrocatalyst, which are derived from zeolitic imidazolate framework (ZIF-67) precursor. It is proposed that the organic ligands in the ZIF-67 can effectively enrich and stabilize the Co(3+) ions in the inorganic-organic frameworks and subsequent carbon-coated nanoparticles. In alkaline media, the catalyst exhibits excellent OER performances, which are attributed to its abundant active sites, high conductivity, and superior kinetics.

  2. Vacancies Ordered in Screw Form (VOSF) and Layered Indium Selenide Thin Film Deposition by Laser Back Ablation

    SciTech Connect

    Beck, Kenneth M.; Wiley, William R.; Venkatasubramanian, Eswaranand; Ohuchi, Fumio S.

    2009-09-30

    Indium selenide thin films are important due to their applications in non-volatile memory and solar cells. In this work, we present an initial study of a new application of deposition-site selective laser back ablation (LBA) for making thin films of In2Se3. In-vacuo annealing and subsequent characterization of the films by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicate that control of substrate temperature during deposition and post-deposition annealing temperature is critical in determining the phase and composition of the films. The initial laser fluence and target film thickness determine the amount of material deposited onto the substrate.

  3. Evaluation of selenide, diselenide and selenoheterocycle derivatives as carbonic anhydrase I, II, IV, VII and IX inhibitors.

    PubMed

    Angeli, Andrea; Tanini, Damiano; Viglianisi, Caterina; Panzella, Lucia; Capperucci, Antonella; Menichetti, Stefano; Supuran, Claudiu T

    2017-04-15

    A series of selenides, diselenides and organoselenoheterocycles were evaluated as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors against the human (h) isoforms hCA I, II, IV, VII and IX, involved in a variety of diseases among which glaucoma, retinitis pigmentosa, epilepsy, arthritis and tumors etc. These investigated compounds showed inhibitory action against these isoforms and some of them were selective for inhibiting the cytosolic over the membrane-bound isoforms, thus making them interesting leads for the development of isoform-selective inhibitors.

  4. The influence of ligand type on self-organization and optical properties of cadmium selenide quantum dots

    NASA Astrophysics Data System (ADS)

    Ushakova, E. V.; Kormilina, T. K.; Burkova, M. A.; Cherevkov, S. A.; Zakharov, V. V.; Turkov, V. K.; Fedorov, A. V.; Baranov, A. V.

    2017-01-01

    A method for successive replacement of organic shells of colloidal cadmium selenide quantum dots (QDs) of different sizes is proposed. It is found that the spectral parameters of QD samples depend on the type of organic shells. It is shown that the structural morphology is independent of the QD size and is determined by the chemical composition of the organic shell. Spectral analysis of the luminescence of QD-based superstructures shows that the luminescence wavelength and intensity strongly depend on the degree of QD surface passivation.

  5. Analysis of space radiation effects in gallium arsenide and cadmium selenide semiconductor samples using luminescence spectroscopic techniques. Master's thesis

    SciTech Connect

    Shaffer, B.L.

    1990-12-01

    Analysis of space radiation effects in gallium arsenide and cadmium selenide semiconductor samples using luminescence spectroscopic techniques. The M0006 semiconductor samples were placed into a 28.5 degree inclination, 480 km altitude, near-circular orbit aboard the Long Duration Exposure Facility satellite and exposed to direct space environment for a period of 11 months, and were shielded by 0.313 inches of aluminum for another 58 months. The samples were examined for changes using cathodoluminescence and photoluminescence in various wavelength regions from 0.5 to 1.8 micrometers. Samples were cooled to approximately 10 degrees Kelvin in a vacuum of 10-8. (JS)

  6. First principles study of electronic and mechanical properties of molybdenum selenide type nanowires

    NASA Astrophysics Data System (ADS)

    Çakır, D.; Durgun, E.; Gülseren, O.; Ciraci, S.

    2006-12-01

    Using the first-principles plane-wave pseudopotential method within density functional theory, we have systematically investigated structural, electronic, and mechanical properties of M2Y6X6 , Y6X6 ( X=Se,Te,S ; Y=Mo,Cr,W ; and M=Li,Na ) nanowires and bulk phase of M2Y6X6 . We found that not only Mo6X6 , but also transition metal and chalcogen atoms lying in the same columns of Mo and Se can form stable nanowires consisting of staggered triangles of Y3X3 . We have shown that all wires have nonmagnetic ground states in their equilibrium geometry. Furthermore, these structures can be either a metal or semiconductor depending on the type of chalcogen element. All Y6X6 wires with X=Te atom are semiconductors. Mechanical stability, elastic stiffness constants, breaking point, and breaking force of these wires have been calculated in order to investigate the strength of these wires. Ab initio molecular dynamic simulations performed at 500K suggest that overall structure remains unchanged at high temperature. Adsorption of H, O, and transition metal atoms like Cr and Ti on Mo6Se6 have been investigated for possible functionalization. All these elements interact with Mo6Se6 wire forming strong chemisorption bonds, and a permanent magnetic moment is induced upon the adsorption of Cr or Ti atoms. Molybdenum selenide-type nanowires can be alternative for carbon nanotubes, since the crystalline ropes consisting of one type of (M2)Y6X6 structures can be decomposed into individual nanowires by using solvents, and an individual nanowire by itself is either a metal or semiconductor and can be functionalized.

  7. Field-effect transistors from lithographically patterned cadmium selenide nanowire arrays.

    PubMed

    Ayvazian, Talin; Xing, Wendong; Yan, Wenbo; Penner, Reginald M

    2012-09-26

    Field-effect transistors (NWFETs) have been prepared from arrays of polycrystalline cadmium selenide (pc-CdSe) nanowires using a back gate configuration. pc-CdSe nanowires were fabricated using the lithographically patterned nanowire electrodeposition (LPNE) process on SiO(2)/Si substrates. After electrodeposition, pc-CdSe nanowires were thermally annealed at 300 °C × 4 h either with or without exposure to CdCl(2) in methanol-a grain growth promoter. The influence of CdCl(2) treatment was to increase the mean grain diameter from 10 to 80 nm as determined by grazing incidence X-ray diffraction and to convert the crystal structure from cubic to wurtzite. Measured transfer characteristics showed an increase of the field effect mobility (μ(eff)) by an order of magnitude from 1.94 × 10(-4) cm(2)/(V s) to 23.4 × 10(-4) cm(2)/(V s) for pc-CdSe nanowires subjected to the CdCl(2) treatment. The CdCl(2) treatment also reduced the threshold voltage (from 20 to 5 V) and the subthreshold slope (by ~35%). Transfer characteristics for pc-CdSe NWFETs were also influenced by the channel length, L. For CdCl(2)-treated nanowires, μ(eff) was reduced by a factor of eight as L increased from 5 to 25 μm. These channel length effects are attributed to the presence of defects including breaks and constrictions within individual pc-CdSe nanowires.

  8. Parallel molecular dynamics simulations of pressure-induced structural transformations in cadmium selenide nanocrystals

    NASA Astrophysics Data System (ADS)

    Lee, Nicholas Jabari Ouma

    Parallel molecular dynamics (MD) simulations are performed to investigate pressure-induced solid-to-solid structural phase transformations in cadmium selenide (CdSe) nanorods. The effects of the size and shape of nanorods on different aspects of structural phase transformations are studied. Simulations are based on interatomic potentials validated extensively by experiments. Simulations range from 105 to 106 atoms. These simulations are enabled by highly scalable algorithms executed on massively parallel Beowulf computing architectures. Pressure-induced structural transformations are studied using a hydrostatic pressure medium simulated by atoms interacting via Lennard-Jones potential. Four single-crystal CdSe nanorods, each 44A in diameter but varying in length, in the range between 44A and 600A, are studied independently in two sets of simulations. The first simulation is the downstroke simulation, where each rod is embedded in the pressure medium and subjected to increasing pressure during which it undergoes a forward transformation from a 4-fold coordinated wurtzite (WZ) crystal structure to a 6-fold coordinated rocksalt (RS) crystal structure. In the second so-called upstroke simulation, the pressure on the rods is decreased and a reverse transformation from 6-fold RS to a 4-fold coordinated phase is observed. The transformation pressure in the forward transformation depends on the nanorod size, with longer rods transforming at lower pressures close to the bulk transformation pressure. Spatially-resolved structural analyses, including pair-distributions, atomic-coordinations and bond-angle distributions, indicate nucleation begins at the surface of nanorods and spreads inward. The transformation results in a single RS domain, in agreement with experiments. The microscopic mechanism for transformation is observed to be the same as for bulk CdSe. A nanorod size dependency is also found in reverse structural transformations, with longer nanorods transforming more

  9. Bacterial Killing by Dry Metallic Copper Surfaces▿

    PubMed Central

    Santo, Christophe Espírito; Lam, Ee Wen; Elowsky, Christian G.; Quaranta, Davide; Domaille, Dylan W.; Chang, Christopher J.; Grass, Gregor

    2011-01-01

    Metallic copper surfaces rapidly and efficiently kill bacteria. Cells exposed to copper surfaces accumulated large amounts of copper ions, and this copper uptake was faster from dry copper than from moist copper. Cells suffered extensive membrane damage within minutes of exposure to dry copper. Further, cells removed from copper showed loss of cell integrity. Acute contact with metallic copper surfaces did not result in increased mutation rates or DNA lesions. These findings are important first steps for revealing the molecular sensitive targets in cells lethally challenged by exposure to copper surfaces and provide a scientific explanation for the use of copper surfaces as antimicrobial agents for supporting public hygiene. PMID:21148701

  10. Reduction of selenate to selenide by sulfate-respiring bacteria: Experiments with cell suspensions and estuarine sediments

    USGS Publications Warehouse

    Zehr, J.P.; Oremland, R.S.

    1987-01-01

    Washed cell suspension of Desulfovibrio desulfuricans subsp. aestuarii were capable of reducing nanomolar levels of selenate to selenide as well as sulfate to sulfide. Reduction of these species was inhibited by 1 mM selenate or tungstate. The addition of 1 mM sulfate decreased the reduction of selenate and enhanced the reduction of sulfate. Increasing concentrations of sulfate inhibited rates of selenate reduction but enhanced sulfate reduction rates. Cell suspensions kept in 1 mM selenate were incapable of reducing either selenate or sulfate when the selenate/sulfate ratio was ???0.02, indicating that irreversible inhibition occurs at high selenate concentrations. Anoxic estuarine sediments having an active flora of sulfate-respiring bacteria were capable of a small amount of selenate reduction when ambient sulfate concentrations were low (<4 mM). These results indicate that sulfate is an inhibitor of the reduction of trace qunatitites of selenate. Therefore, direct reduction of traces of selenate to selenide by sulfate-respiring bacteria in natural environments is constrained by the ambient concentration of sulfate ions. The significance of this observation with regard to the role sediments play in sequestering selenium is discussed

  11. Characterization of bismuth selenide (Bi2Se3) thin films obtained by evaporating the hydrothermally synthesised nano-particles

    NASA Astrophysics Data System (ADS)

    Indirajith, R.; Rajalakshmi, M.; Gopalakrishnan, R.; Ramamurthi, K.

    2016-03-01

    Bismuth selenide (Bi2Se3) was synthesized by hydrothermal method at 200 °C and confirmed by powder X-ray diffraction (XRD) studies. The synthesized material was utilized to deposit bismuth selenide thin films at various substrate temperatures (Room Temperature-RT, 150 °C, 250 °C, 350 °C and 450 °C) by electron beam evaporation technique. XRD study confirmed the polycrystalline nature of the deposited Bi2Se3films. Optical transmittance spectra showed that the deposited (at RT) films acquire relatively high average transmittance of 60%in near infrared region (1500-2500 nm). An indirect allowed optical band gap calculated from the absorption edge for the deposited films is ranging from 0.62 to 0.8 eV. Scanning electron and atomic force microscopy analyses reveal the formation of nano-scale sized particles on the surface and that the nature of surface microstructures is influenced by the substrate temperature. Hall measurements showed improved electrical properties, for the films deposited at 350 °C which possess 2.8 times the mobility and 0.9 times the resistivity of the films deposited at RT.

  12. Phase diagram of (Li(1-x)Fe(x))OHFeSe: a bridge between iron selenide and arsenide superconductors.

    PubMed

    Dong, Xiaoli; Zhou, Huaxue; Yang, Huaixin; Yuan, Jie; Jin, Kui; Zhou, Fang; Yuan, Dongna; Wei, Linlin; Li, Jianqi; Wang, Xinqiang; Zhang, Guangming; Zhao, Zhongxian

    2015-01-14

    Previous experimental results have shown important differences between iron selenide and arsenide superconductors which seem to suggest that the high-temperature superconductivity in these two subgroups of iron-based families may arise from different electronic ground states. Here we report the complete phase diagram of a newly synthesized superconducting (SC) system, (Li1-xFex)OHFeSe, with a structure similar to that of FeAs-based superconductors. In the non-SC samples, an antiferromagnetic (AFM) spin-density-wave (SDW) transition occurs at ∼127 K. This is the first example to demonstrate such an SDW phase in an FeSe-based superconductor system. Transmission electron microscopy shows that a well-known √5×√5 iron vacancy ordered state, resulting in an AFM order at ∼500 K in AyFe2-xSe2 (A = metal ions) superconductor systems, is absent in both non-SC and SC samples, but a unique superstructure with a modulation wave vector q = (1)/2(1,1,0), identical to that seen in the SC phase of KyFe2-xSe2, is dominant in the optimal SC sample (with an SC transition temperature Tc = 40 K). Hence, we conclude that the high-Tc superconductivity in (Li1-xFex)OHFeSe stems from the similarly weak AFM fluctuations as FeAs-based superconductors, suggesting a universal physical picture for both iron selenide and arsenide superconductors.

  13. Room temperature chemical bath deposition of cadmium selenide, cadmium sulfide and cadmium sulfoselenide thin films with novel nanostructures

    NASA Astrophysics Data System (ADS)

    VanderHyde, Cephas A.; Sartale, S. D.; Patil, Jayant M.; Ghoderao, Karuna P.; Sawant, Jitendra P.; Kale, Rohidas B.

    2015-10-01

    A simple, convenient and low cost chemical synthesis route has been used to deposit nanostructured cadmium sulfide, selenide and sulfoselenide thin films at room temperature. The films were deposited on glass substrates, using cadmium acetate as cadmium ion and sodium selenosulfate/thiourea as a selenium/sulfur ion sources. Aqueous ammonia was used as a complex reagent and also to adjust the pH of the final solution. The as-deposited films were uniform, well adherent to the glass substrate, specularly reflective and red/yellow in color depending on selenium and sulfur composition. The X-ray diffraction pattern of deposited cadmium selenide thin film revealed the nanocrystalline nature with cubic phase; cadmium sulfide revealed mixture of cubic along with hexagonal phase and cadmium sulfoselenide thin film were grown with purely hexagonal phase. The morphological observations revealed the growth and formation of interesting one, two and three-dimensional nanostructures. The band gap of thin films was calculated and the results are reported.

  14. Orbital-selective pairing: a τ3 B1g pairing candidate state for the alkaline iron selenides

    NASA Astrophysics Data System (ADS)

    Yu, Rong; Nica, Emilian M.; Si, Qimiao

    The iron-based unconventional superconductors are inherently multi-orbital systems and show remarkable variation in the Fermi-surfaces and pairing symmetries. In the alkaline iron selenides cases, ARPES experiments indicate fully gapped superconducting states, which suggests s-wave pairing, while neutron-scattering studies show resonances in the spin-spectrum with wave vectors across the electron Fermi pockets, suggesting d-wave pairing. We propose a novel superconducting state composed of a direct product of an s-wave form factor and a rotational symmetry-breaking orbital matrix in the dxz / yz sectors. It belongs to the B1 g representation of the D4h point group, allowing for the overall change in sign between the pairing field at the electron pockets close to the 1-Fe BZ edge. While it supports a spin resonance, it also produces a fully gapped quasiparticle spectrum, making it a candidate pairing state for the alkaline iron selenide compounds. Our results also show how such a state can become energetically competitive in the regime of quasi-degeneracy between the s and d-wave pairing states. In a broader context, this pairing provides an alternative to the s + idto reconstruct the degenerate pairing states, while preserving the time-reversal symmetry. We discuss possible analogs in other multi-band strong-coupling superconductors such as the heavy fermions. ''Emergent superconducting state from quasi-degenerate s - and d -wave pairing channels in iron-based superconductors,''.

  15. [{Cp2(tBuSe)Nb}2E] (E = O and Se) with bridging oxide or selenide ligands.

    PubMed

    Hector, Andrew L; Jura, Marek; Levason, William; Reid, Gillian; Reid, Stuart D; Webster, Michael

    2008-10-01

    The title compounds, mu-oxido-bis[(tert-butylselenolato)bis(eta(5)-cyclopentadienyl)niobium(IV)] toluene solvate, [Nb(2)(C(5)H(5))(4)(C(4)H(9)Se)(2)O] x C(7)H(8), and mu-selenido-bis[(tert-butylselenolato)bis(eta(5)-cyclopentadienyl)niobium(IV)], [Nb(2)(C(5)H(5))(4)(C(4)H(9)Se)(2)Se], consist of niobium(IV) centres each bonded to two eta(5)-coordinated cyclopentadienyl groups and one tert-butylselenolate ligand and are the first organometallic niobium selenolates to be structurally characterized. A bridging oxide or selenide completes the niobium coordination spheres of the discrete dinuclear molecules. In the oxide, the O atom lies on an inversion centre, resulting in a linear Nb-O-Nb linkage, whereas the selenide has a bent bridging group [Nb-Se-Nb = 139.76 (2) degrees]. The difference is attributable to strong pi bonding in the oxide case, although the effects on the Nb-C and Nb-Se(t)Bu bond lengths are small.

  16. Soft chemical control of superconductivity in lithium iron selenide hydroxides Li(1-x)Fe(x)(OH)Fe(1-y)Se.

    PubMed

    Sun, Hualei; Woodruff, Daniel N; Cassidy, Simon J; Allcroft, Genevieve M; Sedlmaier, Stefan J; Thompson, Amber L; Bingham, Paul A; Forder, Susan D; Cartenet, Simon; Mary, Nicolas; Ramos, Silvia; Foronda, Francesca R; Williams, Benjamin H; Li, Xiaodong; Blundell, Stephen J; Clarke, Simon J

    2015-02-16

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li(1-x)Fe(x)(OH)Fe(1-y)Se (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron site vacancy concentrations in the iron selenide layers. This iron vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low vacancy concentration in the iron selenide layers is emphasized by the demonstration that reductive postsynthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li(1-x)Fe(x)(OH) reservoir layer to fill vacancies in the selenide layer.

  17. Copper and copper-nickel alloys as zebra mussel antifoulants

    SciTech Connect

    Dormon, J.M.; Cottrell, C.M.; Allen, D.G.; Ackerman, J.D.; Spelt, J.K.

    1996-04-01

    Copper has been used in the marine environment for decades as cladding on ships and pipes to prevent biofouling by marine mussels (Mytilus edulis L.). This motivated the present investigation into the possibility of using copper to prevent biofouling in freshwater by both zebra mussels and quagga mussels (Dreissena polymorpha and D. bugensis collectively referred to as zebra mussels). Copper and copper alloy sheet proved to be highly effective in preventing biofouling by zebra mussels over a three-year period. Further studies were conducted with copper and copper-nickel mesh (lattice of expanded metal) and screen (woven wire with a smaller hole size), which reduced the amount of copper used. Copper screen was also found to be strongly biofouling-resistant with respect to zebra mussels, while copper mesh reduced zebra mussel biofouling in comparison to controls, but did not prevent it entirely. Preliminary investigations into the mechanism of copper antifouling, using galvanic couples, indicated that the release of copper ions from the surface of the exposed metal into the surrounding water is directly or indirectly responsible for the biofouling resistance of copper.

  18. Preparation of high purity copper fluoride by fluorinating copper hydroxyfluoride

    NASA Technical Reports Server (NTRS)

    King, R. B.; Lundquist, J. R.

    1969-01-01

    Copper fluoride containing no more than 50 ppm of any contaminating element was prepared by the fluorination of copper hydroxyfluoride. The impurity content was obtained by spark source mass spectrometry. High purity copper fluoride is needed as a cathode material for high energy density batteries.

  19. 24-hour urine copper test

    MedlinePlus

    ... associated with providing a urine sample. Alternative Names Quantitative urinary copper Images Copper urine test References McPherson ... for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis ...

  20. Agricultural soils spiked with copper mine wastes and copper concentrate: implications for copper bioavailability and bioaccumulation.

    PubMed

    Ginocchio, Rosanna; Sánchez, Pablo; de la Fuente, Luz María; Camus, Isabel; Bustamante, Elena; Silva, Yasna; Urrestarazu, Paola; Torres, Juan C; Rodríguez, Patricio H

    2006-03-01

    A better understanding of exposure to and effects of copper-rich pollutants in soils is required for accurate environmental risk assessment of copper. A greenhouse experiment was conducted to study copper bioavailability and bioaccumulation in agricultural soils spiked with different types of copper-rich mine solid wastes (copper ore, tailing sand, smelter dust, and smelter slag) and copper concentrate. A copper salt (copper sulfate, CuSO4) that frequently is used to assess soil copper bioavailability and phytotoxicity also was included for comparison. Results showed that smelter dust, tailing sand, and CuSO4 are more likely to be bioavailable and, thus, toxic to plants compared with smelter slag, concentrate, and ore at equivalent total copper concentrations. Differences may be explained by intrinsic differences in copper solubilization from the source materials, but also by their capability to decrease soil pH (confounding effect). The copper toxicity and bioaccumulation in plants also varied according to soil physicochemical characteristics (e.g., pH and total organic carbon) and the available levels of plant nutrients, such as nitrogen, phosphorus, and potassium. Chemistry/mineralogy of mine materials, soil/pore-water chemistry, and plant physiological status thus should be integrated for building adequate models to predict phytotoxicity and environmental risk of copper.

  1. Copper-phosphorus alloys offer advantages in brazing copper

    SciTech Connect

    Rupert, W.D.

    1996-05-01

    Copper-phosphorus brazing alloys are used extensively for joining copper, especially refrigeration and air-conditioning copper tubing and electrical conductors. What is the effect of phosphorus when alloyed with copper? The following are some of the major effects: (1) It lowers the melt temperature of copper (a temperature depressant). (2) It increases the fluidity of the copper when in the liquid state. (3) It acts as a deoxidant or a fluxing agent with copper. (4) It lowers the ductility of copper (embrittles). There is a misconception that silver improves the ductility of the copper-phosphorus alloys. In reality, silver added to copper acts in a similar manner as phosphorus. The addition of silver to copper lowers the melt temperature (temperature depressant) and decreases the ductility. Fortunately, the rate and amount at which silver lowers copper ductility is significantly less than that of phosphorus. Therefore, taking advantage of the temperature depressant property of silver, a Ag-Cu-P alloy can be selected at approximately the same melt temperature as a Cu-P alloy, but at a lower phosphorus content. The lowering of the phosphorus content actually makes the alloy more ductile, not the silver addition. A major advantage of the copper-phosphorus alloys is the self-fluxing characteristic when joining copper to copper. They may also be used with the addition of a paste flux on brass, bronze, and specialized applications on silver, tungsten and molybdenum. Whether it is selection of the proper BCuP alloy or troubleshooting an existing problem, the suggested approach is a review of the desired phosphorus content in the liquid metal and how it is being altered during application. In torch brazing, a slight change in the oxygen-fuel ratio can affect the joint quality or leak tightness.

  2. High adherence copper plating process

    DOEpatents

    Nignardot, H.

    1993-09-21

    A process is described for applying copper to a substrate of aluminum or steel by electrodeposition and for preparing the surface of an aluminum or steel substrate for the electrodeposition of copper. Practice of the invention provides good adhesion of the copper layer to either substrate.

  3. Soft X-ray absorption spectroscopy investigation of the surface chemistry and treatments of copper indium gallium diselenide (CIGS)

    SciTech Connect

    Schwartz, Craig; Nordlund, Dennis; Sokaras, Dimosthenis; Contreras, Miguel; Weng, Tsu -Chien; Mansfield, Lorelle; Hurst, Katherine E.; Dameron, Arrelaine; Ramanathan, Kannan; Prendergast, David; Christensen, Steven T.

    2016-11-10

    The surface and near surface structure of the copper-indium-gallium-selenide (CIGS) absorber layer is integral to producing of a high-quality photovoltaic junction. By using X-ray absorption spectroscopy (XAS) and monitoring multiple elemental absorption edges with both theory and experiment, we are able to identify several features of the surface of CIGS as a function of composition and surface treatments. The XAS data shows trends in the near surface region of oxygen, copper, indium and gallium species as the copper content is varied in the films. The oxygen surface species are also monitored through a series of experiments that systematically investigate the effects of water and various solutions of: ammonium hydroxide, cadmium sulfate, and thiourea. These being components of cadmium sulfide chemical bath deposition (CBD). Characteristics of the CBD are correlated with a restorative effect that produces a normalized, uniform surface chemistry as measured by XAS. This surface chemistry is found in CIGS solar cells with excellent power conversion efficiency (~19%). Finally, the results provide new insight for CIGS processing strategies that seek to replace CBD and/or cadmium sulfide.

  4. Soft X-ray absorption spectroscopy investigation of the surface chemistry and treatments of copper indium gallium diselenide (CIGS)

    DOE PAGES

    Schwartz, Craig; Nordlund, Dennis; Sokaras, Dimosthenis; ...

    2016-11-10

    The surface and near surface structure of the copper-indium-gallium-selenide (CIGS) absorber layer is integral to producing of a high-quality photovoltaic junction. By using X-ray absorption spectroscopy (XAS) and monitoring multiple elemental absorption edges with both theory and experiment, we are able to identify several features of the surface of CIGS as a function of composition and surface treatments. The XAS data shows trends in the near surface region of oxygen, copper, indium and gallium species as the copper content is varied in the films. The oxygen surface species are also monitored through a series of experiments that systematically investigate themore » effects of water and various solutions of: ammonium hydroxide, cadmium sulfate, and thiourea. These being components of cadmium sulfide chemical bath deposition (CBD). Characteristics of the CBD are correlated with a restorative effect that produces a normalized, uniform surface chemistry as measured by XAS. This surface chemistry is found in CIGS solar cells with excellent power conversion efficiency (~19%). Finally, the results provide new insight for CIGS processing strategies that seek to replace CBD and/or cadmium sulfide.« less

  5. Cytocompatibility of direct water synthesized cadmium selenide quantum dots in colo-205 cells

    NASA Astrophysics Data System (ADS)

    Rodriguez-Torres, Marcos R.; Velez, Christian; Zayas, Beatriz; Rivera, Osvaldo; Arslan, Zikri; Gonzalez-Vega, Maxine N.; Diaz-Diestra, Daysi; Beltran-Huarac, Juan; Morell, Gerardo; Primera-Pedrozo, Oliva M.

    2015-06-01

    Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring increased attraction due to their highly refined chemistry, availability, and super tunable optical properties suitable for many applications in different research areas, such as photovoltaics, light-emitting devices, environmental sciences, and nanomedicine. Specifically, they are being widely used in bio-imaging in contrast to organic dyes due to their high brightness and improved photo-stability, and their ability to tune their absorption and emission spectra upon changing the crystal size. The production of CdSe QDs is mostly assisted by trioctylphosphine oxide compound, which acts as solvent or solubilizing agent and renders the QDs soluble in organic compounds (such as toluene, chloroform, and hexane) that are highly toxic. To circumvent the toxicity-related factor in CdSe QDs, we report the synthesis of CdSe QDs capped with thioglycolic acid (TGA) in an aqueous medium, and their biocompatibility in colo-205 cancer cells. In this study, the [Cd2+]/[TGA] ratio was adjusted to 11:1 and the Se concentration (10 and 15 mM) was monitored in order to evaluate its influence on the optical properties and cytocompatibility. QDs resulted to be quite stable in water (after purification) and RPMI cell medium and no precipitation was observed for long contact times, making them appealing for in vitro experiments. The spectroscopy analysis, advanced electron microscopy, and X-ray diffractometry studies indicate that the final products were successfully formed exhibiting an improved optical response. Colo-205 cells being exposed to different concentrations of TGA-capped CdSe QDs for 12, 24, and 48 h with doses ranging from 0.5 to 2.0 mM show high tolerance reaching cell viabilities as high as 93 %. No evidence of cellular apoptotic pathways was observed as pointed out by our Annexin V assays at higher concentrations. Moreover, confocal microscopy analysis conducted to evaluate the

  6. Cytocompatibility of direct water synthesized cadmium selenide quantum dots in colo-205 cells.

    PubMed

    Rodriguez-Torres, Marcos R; Velez, Christian; Zayas, Beatriz; Rivera, Osvaldo; Arslan, Zikri; Gonzalez-Vega, Maxine N; Diaz-Diestra, Daysi; Beltran-Huarac, Juan; Morell, Gerardo; Primera-Pedrozo, Oliva M

    2015-06-01

    Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring increased attraction due to their highly refined chemistry, availability, and super tunable optical properties suitable for many applications in different research areas, such as photovoltaics, light-emitting devices, environmental sciences, and nanomedicine. Specifically, they are being widely used in bio-imaging in contrast to organic dyes due to their high brightness and improved photo-stability, and their ability to tune their absorption and emission spectra upon changing the crystal size. The production of CdSe QDs is mostly assisted by trioctylphosphine oxide compound, which acts as solvent or solubilizing agent and renders the QDs soluble in organic compounds (such as toluene, chloroform, and hexane) that are highly toxic. To circumvent the toxicity-related factor in CdSe QDs, we report the synthesis of CdSe QDs capped with thioglycolic acid (TGA) in an aqueous medium, and their biocompatibility in colo-205 cancer cells. In this study, the [Cd(2+)]/[TGA] ratio was adjusted to 11:1 and the Se concentration (10 and 15 mM) was monitored in order to evaluate its influence on the optical properties and cytocompatibility. QDs resulted to be quite stable in water (after purification) and RPMI cell medium and no precipitation was observed for long contact times, making them appealing for in vitro experiments. The spectroscopy analysis, advanced electron microscopy, and X-ray diffractometry studies indicate that the final products were successfully formed exhibiting an improved optical response. Colo-205 cells being exposed to different concentrations of TGA-capped CdSe QDs for 12, 24, and 48 h with doses ranging from 0.5 to 2.0 mM show high tolerance reaching cell viabilities as high as 93 %. No evidence of cellular apoptotic pathways was observed as pointed out by our Annexin V assays at higher concentrations. Moreover, confocal microscopy analysis conducted to evaluate

  7. Cytocompatibility of direct water synthesized cadmium selenide quantum dots in colo-205 cells

    PubMed Central

    Rodriguez-Torres, Marcos R.; Velez, Christian; Zayas, Beatriz; Rivera, Osvaldo; Arslan, Zikri; Gonzalez-Vega, Maxine N.; Diaz-Diestra, Daysi; Beltran-Huarac, Juan; Morell, Gerardo

    2015-01-01

    Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring increased attraction due to their highly refined chemistry, availability, and super tunable optical properties suitable for many applications in different research areas, such as photovoltaics, light-emitting devices, environmental sciences, and nanomedicine. Specifically, they are being widely used in bio-imaging in contrast to organic dyes due to their high brightness and improved photo-stability, and their ability to tune their absorption and emission spectra upon changing the crystal size. The production of CdSe QDs is mostly assisted by trioctylphosphine oxide compound, which acts as solvent or solubilizing agent and renders the QDs soluble in organic compounds (such as toluene, chloroform, and hexane) that are highly toxic. To circumvent the toxicity-related factor in CdSe QDs, we report the synthesis of CdSe QDs capped with thioglycolic acid (TGA) in an aqueous medium, and their biocompatibility in colo-205 cancer cells. In this study, the [Cd2+]/[TGA] ratio was adjusted to 11:1 and the Se concentration (10 and 15 mM) was monitored in order to evaluate its influence on the optical properties and cytocompatibility. QDs resulted to be quite stable in water (after purification) and RPMI cell medium and no precipitation was observed for long contact times, making them appealing for in vitro experiments. The spectroscopy analysis, advanced electron microscopy, and X-ray diffractometry studies indicate that the final products were successfully formed exhibiting an improved optical response. Colo-205 cells being exposed to different concentrations of TGA-capped CdSe QDs for 12, 24, and 48 h with doses ranging from 0.5 to 2.0 mM show high tolerance reaching cell viabilities as high as 93 %. No evidence of cellular apoptotic pathways was observed as pointed out by our Annexin V assays at higher concentrations. Moreover, confocal microscopy analysis conducted to evaluate the

  8. Formation of dimethyl selenide and trimethylselenonium from selenobetaine in the rat

    SciTech Connect

    Foster, S.J.; Kraus, R.J.; Ganther, H.E.

    1986-05-15

    The 24-h respiratory excretion of dimethyl selenide (DMSe) and urinary excretion of trimethylselenonium (TMSe) were studied in adult male rats injected with 2 mg Se/kg as selenobetaine ((CH/sub 3/)2Se+CH/sub 2/COOH) or its methyl ester, labeled with /sup 75/Se and /sup 14/C. The DMSe was trapped by means of 20% benzyl chloride in xylene. TMSe was measured by cation exchange high performance liquid chromatography. There was extensive respiratory excretion of DMSe from selenobetaine methyl ester (about 50% of the dose) and from selenobetaine (about 25%). About 12% of the dose was converted to TMSe for both compounds. When the Se-methyl carbons were labeled with /sup 14/C and the selenium with /sup 75/Se, doubly labeled DMSe and TMSe were formed; the /sup 14/C//sup 75/Se ratio in DMSe formed from selenobetaine methyl ester was almost unchanged from that administered, and the ratio in TMSe was only slightly lower than in DMSe. In contrast to its ester, doubly labeled selenobetaine yielded DMSe having a lower /sup 14/C//sup 75/Se ratio (approximately one-half of that administered) and a further decrease was observed between DMSe and TMSe. These data indicate that the (CH3)2Se moiety in selenobetaine methyl ester undergoes facile release to form DMSe, which is directly methylated to form TMSe. Selenobetaine, however, appears to lose a methyl group prior to scission of the Se-CH2COOH bond. The results with selenobetaine also suggest that TMSe generated metabolically is not inert, and can undergo demethylation followed by remethylation; confirmatory evidence for this metabolic instability is provided by the exhalation of (/sup 75/Se)DMSe after the direct administration of (/sup 75/Se)TMSe. When (/sup 75/Se)selenobetaine or its ester was given with the methylene carbon in the acetic acid molabeled with /sup 14/C, only /sup 75/Se was present in the DMSe and TMSe.

  9. Brazing copper to dispersion-strengthened copper

    SciTech Connect

    Ryding, D.G.; Allen, D.; Lee, R.

    1996-08-01

    The Advanced Photon Source (APS) is a state-of-the-art synchrotron light source that will produce intense x-ray beams, which will allow the study of smaller samples and faster reactions and processes at a greater level of detail that has been possible to date. The beam is produced by using third-generation insertion devices in a 7 GeV electron/positron storage ring that is 1100 meters in circumference. The heat load from these intense high power devices is very high and certain components must sustain total heat loads of 3 to 15 kW and heat fluxes of 30 W/mm{sup 2}. Because the beams will cycle on and off many times, thermal shock and fatigue will be a problem. High heat flux impinging on a small area causes a large thermal gradient that results in high stress. GlidCop{reg_sign}, a dispersion strengthened copper, is the desired material because of its high thermal conductivity and superior mechanical properties as compared to copper and its alloys. GlidCop is not amenable to joining by fusion welding, and brazing requires diligence because of high diffusivity. Brazing procedures were developed using optical and scanning electron microscopy.

  10. Creative Copper Crests

    ERIC Educational Resources Information Center

    Knab, Thomas

    2011-01-01

    In this article, the author discusses how to create an art activity that would link the computer-created business cards of fourth-grade students with an upcoming school-wide medieval event. Creating family crests from copper foil would be a great connection, since they, like business cards, are an individual's way to identify themselves to others.…

  11. A novel polysaccharide isolated from mulberry fruits (Murus alba L.) and its selenide derivative: structural characterization and biological activities.

    PubMed

    Chen, Chun; Zhang, Bin; Fu, Xiong; Liu, Rui Hai

    2016-06-15

    A novel polysaccharide (MFP3P) was isolated from Murus alba L. through the hot water extraction method followed by chromatographic purification. The chemical structure of MFP3P was elucidated by acid hydrolysis, Smith degradation and methylation analysis, along with FT-IR, GC-MS, (1)H and (13)C NMR spectroscopy. Its morphological properties were further characterized by SEM and AFM. The selenide of the polysaccharide (MFP3P-Se) was obtained by the Na2SeO3/BaCl2 method. The antioxidant properties showed that MFP3P-Se exhibited higher peroxy radical-scavenging capacity than MFP3P in vitro. Moreover, MFP3P-Se had more significant hypoglycemic effects than MFP3P through promoting pancreatic cell proliferation and increasing glucose metabolism and insulin secretion.

  12. A Molecular Ni-complex Containing Tetrahedral Nickel Selenide Core as Highly Efficient Electrocatalyst for Water Oxidation.

    PubMed

    Masud, Jahangir; Ioannou, Polydoros-Chrysovalantis; Levesanos, Nikolaos; Kyritsis, Panayotis; Nath, Manashi

    2016-11-23

    We report the highly efficient catalytic activity of a transition metal selenide-based coordination complex, [Ni{(SeP(i) Pr2 )2 N}2 ], (1) for oxygen evolution and hydrogen evolution reactions (OER and HER, respectively) in alkaline solution. Very low overpotentials of 200 mV and 310 mV were required to achieve 10 mA cm(-2) for OER and HER, respectively. The overpotential for OER is one of the lowest that has been reported up to now, making this one of the best OER electrocatalysts. In addition, this molecular complex exhibits an exceptionally high mass activity (111.02 A g(-1) ) and a much higher TOF value (0.26 s(-1) ) at a overpotential of 300 mV. This bifunctional electrocatalyst enables water electrolysis in alkaline solutions at a cell voltage of 1.54 V.

  13. Calculation of the structural parameters of small cadmium selenide clusters, (CdSe)n, n = 1,2,3

    NASA Astrophysics Data System (ADS)

    Alselawe, A. I. A.; Gopir, G.; Anas, M. M.

    2016-11-01

    The structural parameters of small cadmium selenide clusters (CdSe)n, for n=1,2, and 3 were studied. The calculations were performed using the pseudopotential and planewave basis sets, within the density functional theory. These parameters for geometry optimization can be used as elementary information for further investigations. The total energy calculations for the three linear structures of (CdSe)2 showed that these isomers are close in their stability. The rhombus structure (CdSe)2 planar is more stable isomer. The bond distances for the different structures show that the distances decrease with increasing the atoms in the structure. The calculated bond angles were close to other relevant studies.

  14. Observation of Low-Temperature Softening of Transverse Elastic Modulus Due to Cobalt Impurities in Mercury Selenide

    NASA Astrophysics Data System (ADS)

    Zhevstovskikh, Irina V.; Okulov, Vsevolod I.; Gudkov, Vladimir V.; Sarychev, Maksim N.; Medvedev, Kirill A.; Andriichuk, Myroslav D.; Paranchich, Lidiya D.

    2016-12-01

    Influence on elastic moduli of donor electron d-states of cobalt impurities has been investigated in mercury selenide crystals. Experiments have been carried out at the frequency of 53 MHz in the temperature interval of 1.3-100 K. Softening of the (C_{11} - C_{12})/2 modulus below 10 K has been observed in the impurity crystals in contrast with the (C_{11} + C_{12} + 2C_{44})/2 and C_{44} moduli those have exhibited hardening at cooling typical for dielectric and semiconductor crystals. The softening of the elastic modulus has been interpreted as manifestation of hybridization of the impurity d-states in the conduction band of the crystal. Comparison of theoretical calculations with experimental data has been proved to be in good agreement and has made it possible to determine the parameters characterizing the hybridized electron states.

  15. Optoelectronic characteristics of inorganic/organic hybrid device based on poly(N-vinylcarbazole)/ cadmium selenide thin films.

    PubMed

    Tang, Aiwei; Teng, Feng; Hou, Yanbing; Xiong, Sha; Feng, Bin; Qian, Lei; Wang, Yongsheng

    2008-03-01

    Inorganic/organic hybrid light-emitting diodes were easily fabricated with a thin film containing water-soluble cadmium selenide nanocrystals and poly(N-vinylcarbazole) as an emitting layer by a spin-coating method. The cadmium selenide nanocrystals were synthesized in aqueous solution with L-cysteine hydrochloride as the stabilizer and were transferred from the aqueous solution into chloroform by a cationic surfactant cetyltrimethyl ammonium bromide. A broad emission spanning the whole visible wavelength range was obtained from the inorganic/organic hybrid devices whether poly(N-vinylcarbazole) was present in the devices or not, and the electroluminescence intensity of the devices increased as the applied voltages increased. However, an obvious blue-shift of the wavelength was observed with the increasing applied voltages in the device with poly(N-vinylcarbazole). Accordingly, the emission color of the device made with poly(N-vinylcarbazole) could be tuned from white to blue by varying the applied voltages, but the emission color of the device made without poly(N-vinylcarbazole) was almost constrained in the white region. This can be attributed to a limited contribution of poly(N-vinylcarbazole) emission to the electroluminescence spectra under the higher applied voltage. By comparing the electroluminescence intensity and the current-voltage characteristics of the devices made with and without poly(N-vinylcarbazole), the performance of the device with poly(N-vinylcarbazole) was improved greatly, which indicated that poly(N-vinylcarbazole) played an important role in the carrier injection and transportation in the device with poly(N-vinylcarbazole).

  16. Production of ultrahigh purity copper using waste copper nitrate solution.

    PubMed

    Choi, J Y; Kim, D S

    2003-04-25

    The production of ultrahigh purity copper (99.9999%) by electrolysis in the presence of a cementation barrier has been attempted employing a waste nitric copper etching solution as the electrolyte. The amount of copper deposited on the cathode increased almost linearly with electrolysis time and the purity of copper was observed to increase as the electrolyte concentration was increased. At some point, however, as the electrolyte concentration increased, the purity of copper decreased slightly. As the total surface area of cementation barrier increased, the purity of product increased. The electrolyte temperature should be maintained below 35 degrees C in the range of investigated electrolysis conditions to obtain the ultrahigh purity copper. Considering that several industrial waste solutions contain valuable metallic components the result of present study may support a claim that electrowinning is a very desirable process for their treatment and recovery.

  17. 197Au Mössbauer study of copper refinery anode slimes

    NASA Astrophysics Data System (ADS)

    Sawicki, J. A.; Dutrizac, J. E.; Friedl, J.; Wagner, F. E.; Chen, T. T.

    1993-06-01

    Copper refinery anode slimes are abundantly produced during the electrolytic refining of copper. Although the slimes contain significant and economically recoverable amounts of gold and silver, the chemical state of the gold has not been fully identified. In the present work, the chemical form of gold in a copper anode, in a raw slime, and in slimes treated by different leaching procedures has been investigated by Mössbauer spectroscopy with the 77.3 keV γ-rays of197Au. The Mössbauer spectrum of the anode is typical of a dilute Au:Cu alloy. The spectrum of the raw slime consists of two components, namely, a single, rather broad line with an isomer shift (IS) of about -0.3 mm/s relative to a Pt metal source and a quadrupole doublet with an IS of + 1.2 mm/s and a quadrupole splitting of 5.0 mm/s. The single line component can be attributed to a gold-rich alloy, with an approximate composition of Au60Ag{n40} or Au80Cu20 if it is a binary alloy, or to a ternary Au-Ag-Cu alloy of appropriate composition. The parameters of the quadrupole doublet match those of Ag3AuSe2 (fischesserite) or related Ag2-xAuxSe compounds. In these compounds, the gold atoms are coordinated by two selenium atoms in a linear arrangement, as is typical for Au(I). It was found that the ratio between the concentrations of the metallic phase and the selenide strongly depends on the leaching conditions. The measurement of the Lamb-Mössbauer factor of fischesserite is also reported.

  18. Copper Vapor Generator

    DTIC Science & Technology

    1974-09-01

    percent measured during this program in a static copper vapor apparatus developed at PIB . This efficiency has been calculated by dividing the energy of a... laser medium. A measure of beam quality may be defined in terms ot the energy delivered in the tar field in relatum to the energy delivered by a...phase of the work the homogeneity requirements for the medium of a high -power laser was reviewed. These requirements were translated into measurable

  19. Vanadium-catalyzed selenide oxidation with in situ [2,3] sigmatropic rearrangement (SOS reaction): scope and asymmetric applications†‡

    PubMed Central

    Campbell Bourland, T.; Yokochi, Alexandre F. T.

    2008-01-01

    A vanadium-catalyzed method for the oxidation of prochiral aryl, allylic selenides with tandem [2,3] sigmatropic rearrangement has been developed. This protocol has been screened on a series of substrates to test for its generality and effectiveness. The applicability of this methodology to the synthesis of enantiomerically enriched allylic alcohols has been studied on a series of chiral oxazole-containing systems with a diastereomeric ratio (d.r.) of up to 85 : 15. The chiral transfer observed in the allyl alcohol products is the result of a net 1,9- and/or 1,10-induction. Finally, the first example of a selenium–oxygen nonbonding interaction in oxazole-containing selenide appears to have been observed via X-ray crystal analysis. PMID:15105922

  20. Passively Q-switched Erbium-doped and Ytterbium-doped fibre lasers with topological insulator bismuth selenide (Bi2Se3) as saturable absorber

    NASA Astrophysics Data System (ADS)

    Haris, H.; Harun, S. W.; Muhammad, A. R.; Anyi, C. L.; Tan, S. J.; Ahmad, F.; Nor, R. M.; Zulkepely, N. R.; Arof, H.

    2017-02-01

    This paper portrays a simple Q-switched Erbium-doped fibre (EDF) and Ytterbium doped fibre (YDF) lasers by using topological insulator (TI) Bismuth Selenide (Bi2Se3) as saturable absorber. The modulation depth of the fabricated Bi2Se3 is about 39.8% while its saturating intensity is about 90.2 MW/cm2. By depositing the TI Bi2Se3 SA onto fibre ferrules and incorporate it inside the proposed cavity, a stable Q-switching operation was achieved at 1 μm and 1.5 μm. The fabricated Bismuth Selenide (Bi2Se3) as saturable absorber (SA) is a broadband SA where it offers a compact and low cost fabrication which is beneficial in various photonic applications.

  1. Anodic electrosynthesis of cadmium selenide thin films; Characterization and comparison with the passive/transpassive behavior of CdX (X = S,Te) counterpart

    SciTech Connect

    Ham, D.; Mishra, K.K.; Rajeshwar, K. )

    1991-01-01

    This paper reports on cadmium selenide thin films electrosynthesized by an anodic route employing alkaline selenide solutions. The thermodynamic aspects of the electrodeposition chemistry were first explored via Pourbaix diagrams; the kinetic aspects were studied by linear sweep voltammetry on a Cd anode. The photoaction spectra of these anodic thin films revealed an optical gap energy (1.7 eV) in good agreement with the value known for CdSe. Their luminescence response, however, suggested a high density of carrier recombination centers located {approximately}0.2 eV below the conduction band. X-ray photoelectron spectroscopy revealed that the anodic thin films were stoichiometric in composition. In situ examination of the material during thin film growth by cyclic photovoltammetry revealed anodic photoeffects at potentials just past the Cd corrosion wave. The growth kinetics in the passive region adhered to a direct logarithmic rate law, while a diffusion mechanism was seen to prevail in the transpassive regime.

  2. Copper corrosion in coastal Oregon

    SciTech Connect

    Ballard, Sophie J.; Cramer, Stephen D.; Covino, Bernard S. Jr.; Holcomb, Gordon R.

    1998-01-01

    The US Department of Energy is studying the atmospheric corrosion performance of copper and other metals along the Oregon coast. Only the copper results will be presented in this paper. Atmospheric corrosion measurements of copper samples were made at seven bridges, eight coastal communities, and three inland reference sites to quantify and understand the effect of high chloride environments on the corrosion performance of copper. The materials were atmospherically exposed for 1, 2, and 3 years to examine the effects of sheltering, orientation, distance from the ocean, and coastal microclimates on the rate of corrosion and the composition of the corrosion film.

  3. Synthesis and characterization of (Ni1-xCox)Se2 based ternary selenides as electrocatalyst for triiodide reduction in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Theerthagiri, J.; Senthil, R. A.; Buraidah, M. H.; Raghavender, M.; Madhavan, J.; Arof, A. K.

    2016-06-01

    Ternary metal selenides of (Ni1-xCox)Se2 with 0≤x≤1 were synthesized by using one-step hydrothermal reduction route. The synthesized metal selenides were utilized as an efficient, low-cost platinum free counter electrode for dye-sensitized solar cells. The cyclic voltammetry and electrochemical impedance spectroscopy studies revealed that the Ni0.5Co0.5Se2 counter electrode exhibited higher electrocatalytic activity and lower charge transfer resistance at the counter electrode/electrolyte interface than the other compositions for reduction of triiodide to iodide. Ternary selenides of Ni0.5Co0.5Se2 offer a synergistic effect to the electrocatalytic activity for the reduction of triiodide that might be due to an increase in active catalytic sites and small charge transfer resistance. The DSSC with Ni0.5Co0.5Se2 counter electrode achieved a high power conversion efficiency of 6.02%, which is comparable with that of conventional platinum counter electrode (6.11%). This present investigation demonstrates the potential application of Ni0.5Co0.5Se2 as counter electrode in dye-sensitized solar cells.

  4. Removal of copper from ferrous scrap

    DOEpatents

    Blander, M.; Sinha, S.N.

    1990-05-15

    A process for removing copper from ferrous or other metal scrap in which the scrap is contacted with a polyvalent metal sulfide slag in the presence of an excess of copper-sulfide forming additive to convert the copper to copper sulfide which is extracted into the slag to provide a ratio of copper in the slag to copper in the metal scrap of at least about 10.

  5. Removal of copper from ferrous scrap

    DOEpatents

    Blander, M.; Sinha, S.N.

    1987-07-30

    A process for removing copper from ferrous or other metal scrap in which the scrap is contacted with a polyvalent metal sulfide slag in the presence of an excess of copper-sulfide forming additive to convert the copper to copper sulfide which is extracted into the slag to provide a ratio of copper in the slag to copper in the metal scrap of at least about 10.

  6. Removal of copper from ferrous scrap

    DOEpatents

    Blander, Milton; Sinha, Shome N.

    1990-01-01

    A process for removing copper from ferrous or other metal scrap in which the scrap is contacted with a polyvalent metal sulfide slag in the presence of an excess of copper-sulfide forming additive to convert the copper to copper sulfide which is extracted into the slag to provide a ratio of copper in the slag to copper in the metal scrap of at least about 10.

  7. Evidence for the involvement of the serotonergic 5-HT2A/C and 5-HT3 receptors in the antidepressant-like effect caused by oral administration of bis selenide in mice.

    PubMed

    Jesse, Cristiano R; Wilhelm, Ethel A; Bortolatto, Cristiani F; Nogueira, Cristina W

    2010-03-17

    The present study investigated a possible antidepressant-like activity of bis selenide using two predictive tests for antidepressant effect on rodents: the forced swimming test (FST) and the tail suspension test (TST). Bis selenide (0.5-5 mg/kg, p.o.) decreased the immobility time in the mouse FST and TST. The anti-immobility effect of bis selenide (1 mg/kg, p.o.) in the TST was prevented by the pretreatment of mice with p-chlorophenylalanine methyl ester (PCPA; 100 mg/kg, i.p., an inhibitor of serotonin synthesis), ketanserin (1 mg/kg, i.p., a 5-HT(2A/2C) receptor antagonist), and ondasentron (1 mg/kg, i.p., a 5-HT(3) receptor antagonist). Pretreatment of mice with prazosin (1 mg/kg, i.p., an alpha(1)-adrenoceptor antagonist), yohimbine (1 mg/kg, i.p., an alpha(2)-adrenoceptor antagonist), propranolol (2 mg/kg, i.p., a beta-adrenoceptor antagonist), SCH23390 (0.05 mg/kg, s.c., a dopamine D(1) receptor antagonist), sulpiride (50 mg/kg, i.p., a dopamine D(2) receptor antagonist), or WAY 100635 (0.1 mg/kg, s.c., a selective 5-HT(1A) receptor antagonist) did not block the antidepressant-like effect of bis selenide (1 mg/kg, p.o.) in the TST. Administration of bis selenide (0.1 mg/kg, p.o.) and fluoxetine (1 mg/kg), at subeffective doses, produced an antidepressant-like effect in the TST. Bis selenide did not alter Na(+) K(+) ATPase, MAO-A and MAO-B activities in whole brains of mice. Bis selenide produced an antidepressant-like effect in the mouse TST and FST, which may be related to the serotonergic system (5-HT(2A/2C) and 5-HT(3) receptors).

  8. The effect of silicon and copper-indium-gallium-selenide based solar cell structures and processing on temperature dependent performance losses

    NASA Astrophysics Data System (ADS)

    Hsieh, Judith

    Temperature dependent current voltage measurements (J-V-T) of solar cells. provide both fundamental and practical information. They give detailed insight into. recombination losses within the device as well as information about module. performance losses at higher outdoor operating temperatures. In this thesis, J-V-T. measurements were applied to two distinctly different types of solar cells: crystalline. silicon heterojunction cells and thin film (AgCu)(InGa)Se2 or ACIGS polycrystalline. cells. Crystalline silicon solar cells with heterojunction structure improve the opencircuit. voltage and efficiency. Interdigitated back contact (IBC) Si solar cells obtain a. higher short-circuit current and fill factor compared to front heterojunction (FHJ) solar. cells. ACIGS solar cells have shown higher efficiencies at wider bandgap compared to. the baseline CIGS solar cells. Two high open-circuit voltage CIGS solar cells are. included and compared with ACIGS solar cells. In this thesis, the impact of different. types of solar cells structure and fabrication on temperature dependent performance. losses will be discussed. Devices with higher bandgap are predicted to have higher. open-circuit voltage and lower temperature coefficient of maximum power output. (Pmax). The correlation between temperature coefficient of Pmax and open-circuit. voltage can be found in Si FHJ cells but not Si IBC or ACIGS cells. However, ACIGS. cells show an inverse correlation between temperature coefficient of Pmax and bandgap. as expected. Analysis of diode quality factor and other parameters are interpreted. Sshape. J-V curve can reduce the device's fill factor with a relative high series resistance. This phenomenon tends to occur in FHJ cells rather than IBC at low temperature. Light-dark crossover and roll over effects are commonly seen in ACIGS cells and the. anomaly is enhanced at lower temperature. Most of FHJ and IBC cells obtain the. ideality factor between 1 and 2 while some of ACIGS cells obtain the ideality factor. less than 1 or larger than 2. The value of the ideality factor may be limited by different. recombination mechanism.

  9. Synthesis of copper/copper oxide nanoparticles by solution plasma

    NASA Astrophysics Data System (ADS)

    Saito, Genki; Hosokai, Sou; Tsubota, Masakatsu; Akiyama, Tomohiro

    2011-07-01

    This paper describes the synthesis of copper/copper oxide nanoparticles via a solution plasma, in which the effect of the electrolyte and electrolysis time on the morphology of the products was mainly examined. In the experiments, a copper wire as a cathode was immersed in an electrolysis solution of a K2CO3 with the concentration from 0.001 to 0.50 M or a citrate buffer (pH = 4.8), and was melted by the local-concentration of current. The results demonstrated that by using the K2CO3 solution, we obtained CuO nanoflowers with many sharp nanorods, the size of which decreased with decreasing the concentration of the solution. Spherical particles of copper with/without pores formed when the citrate buffer was used. The pores in the copper nanoparticles appeared when the applied voltage changed from 105 V to 130 V, due to the dissolution of Cu2O.

  10. Copper mediated carbometalation reactions.

    PubMed

    Müller, D S; Marek, I

    2016-08-08

    Since the first discovery of carbocupration of alkynes in the 1970s a tremendous amount of research has been carried out in this field. The exceptionally high selectivities obtained attribute to the great synthetic value of carbocupration reactions. This tutorial review will present the most important features of carbocupration of alkynes and highlight the most relevant reviews. Then a comprehensive review of copper mediated carbometalation of cyclopropenes will follow. The latter method has received much attention over the last decade as it allows the highly selective construction of poly-substituted cyclopropanes which can be transformed into acyclic derivatives bearing one or multiple tertiary or quaternary carbon stereocenters.

  11. Antimony activities in copper mattes

    NASA Astrophysics Data System (ADS)

    Hino, M.; Toguri, J. M.

    1987-03-01

    A mass spectrometric technique combined with a double Knudsen cell was used to determine the antimony and copper activities in the Cu-Sb binary system at 1373 K and in the two-melt composition range of the Cu-S-Sb ternary system at 1423 K. The antimony and copper activities were calculated based on the intensity ration of the gaseous Sb and Cu species, over the unknown and known activity samples, respectively. γ{Sb/o} were found to be 1.1×10-2 in molten copper at 1373 K, and 1.8×10-2 and 0.44 in a copper-rich phase and in a matter phase, of the Cu-S-Sb ternary system at 1423 K, respectively. These values indicate, that antimony can be removed during the matte smelting and slagging stage of the copper smelting process. Interaction parameters of antimony in molten copper slagging stage of the copper smelting process. Interaction parameters of antimony in molten copper at 1423 K were calculated and found to be 10.7, -5.4, and 6.3 for ɛ{Sb/Sb} · ρSb Sb, and ɛ{Sb/S}, respectively.

  12. Lead and Copper Control 101

    EPA Science Inventory

    This presentation is an overview of the most important water treatment strategies for the control of lead and copper release from drinking water corrosion. In addition to the sections specifically on lead and copper treatment, sections are included that cover sampling to find le...

  13. Nano-scale Characteristics of Copper poor ordered defect compound at grain boundary of CuInGaSe2

    NASA Astrophysics Data System (ADS)

    Ma, Yaping

    This work investigates the copper poor ordered defect compound (ODC) layer at grain boundaries (GB) for CuX(Ga0.3In0.7) Se2 with different Cu composition ratio (x = 0.9 and 0.68). Same chemical composition while widened ODC layer at GBs with lower Cu ratio were first reported determined by the energy dispersive spectroscopy in scanning transmission microscopy mode. Band structure of the ODC layer was directly measured by scanning tunneling spectroscopy showing a downward offset for conduction band and valance band of 200 eV and 350 eV, respectively. This result was further confirmed by photocurrent accumulation and higher schottky barrier at GBs measured by the conducting probe atomic force microscopy (CP-AFM). Local photovoltaic performance measurements of individual grain boundaries with different ODC width were investigated, using CP-AFM and the disappearance of the differences of open circuit voltage and shunt resistance between grain interior and grain boundary at low illumination provides a direct evidence for the reduced recombination at widened ODC grain boundary which greatly supports the hole barrier theory for the high efficiency of the Copper Indium Ga Selenide solar cells.

  14. Effects of copper(II) and copper oxides on THMs formation in copper pipe.

    PubMed

    Li, Bo; Qu, Jiuhui; Liu, Huijuan; Hu, Chengzhi

    2007-08-01

    Little is known about how the growth of trihalomethanes (THMs) in drinking water is affected in copper pipe. The formation of THMs and chlorine consumption in copper pipe under stagnant flow conditions were investigated. Experiments for the same water held in glass bottles were performed for comparison. Results showed that although THMs levels firstly increased in the presence of chlorine in copper pipe, faster decay of chlorine as compared to the glass bottle affected the rate of THMs formation. The analysis of water phase was supplemented by surface analysis of corrosion scales using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDX). The results showed the scales on the pipe surface mainly consisted of Cu(2)O, CuO and Cu(OH)(2) or CuCO(3). Designed experiments confirmed that the fast depletion of chlorine in copper pipe was mainly due to effect of Cu(2)O, CuO in corrosion scales on copper pipe. Although copper(II) and copper oxides showed effect on THMs formation, the rapid consumption of chlorine due to copper oxide made THM levels lower than that in glass bottles after 4h. The transformations of CF, DCBM and CDBM to BF were accelerated in the presence of copper(II), cupric oxide and cuprous oxide. The effect of pH on THMs formation was influenced by effect of pH on corrosion of copper pipe. When pH was below 7, THMs levels in copper pipe was higher as compared to glass bottle, but lower when pH was above 7.

  15. Optical Properties of Copper Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kalenskii, A. V.; Zvekov, A. A.; Nikitin, A. P.; Anan'eva, M. V.

    2015-12-01

    Spectral dependences of the light extinction, absorption, and scattering efficiency factors of copper nanoparticles attendant to variations of their radii are calculated. A plasmon maximum is observed on the spectral dependence of the extinction efficiency factor for nanoparticle radii 10-60 nm. The maximum of the absorption efficiency factor is shifted toward red wavelengths with increasing radius of copper nanoparticles. Results are interpreted based on the special features of the spectral dependence of the complex copper refractive index. It is shown that the copper nanoparticles with radius of 35 nm placed into a transparent matrix with refractive index of 1.54 (secondary explosive pentaerythritol tetranitrate) possess a very high value of the absorption efficiency factor (2.9) of the second harmonic of a neodymium laser. Our investigations suggest that the copper nanoparticles are perspective material for application in compositions for optical detonator capsules.

  16. Role of different types of potassium channels and peroxisome proliferator-activated receptors γ in the antidepressant-like activity of bis selenide in the mouse tail suspension test.

    PubMed

    Jesse, Cristiano R; Wilhelm, Ethel A; Bortolatto, Cristiani F; Nogueira, Cristina W

    2011-03-03

    In the present study we investigated the role of potassium (K(+)) channels and peroxisome proliferator-activated receptor gamma (PPARγ) in the antidepressant-like effect of bis selenide in the mouse tail suspension test (TST). Intracerebroventricular (i.c.v.) pretreatment with tetraethyl ammonium (TEA, a non-specific inhibitor of K(+) channels, 25 pg/site), glibenclamide (an ATP-sensitive K(+) channel inhibitor, 0.5 pg/site), charybdotoxin (a large and intermediate conductance calcium-activated K(+) channel inhibitor, 25 pg/site) or apamin (a small-conductance calcium-activated K(+) channel inhibitor, 10 pg/site) produced a synergistic action with a sub effective dose of bis selenide (0.1 mg/kg, per oral--p.o.). Picrotoxin (1 mg/kg, intraperitoneally--i.p.) pretreatment did not prevent the reduction in immobility time elicited by bis selenide (1 mg/kg, p.o.) in the TST. The reduction in the immobility time elicited by an effective dose of bis selenide (1 mg/kg, p.o.) was prevented by the pretreatment of mice with cromakalim, minoxidil (K(+) channel openers, 10 μg/site, i.c.v.) and GW 9662 (a PPARγ antagonist, 10 μg/site, i.c.v.). The findings clearly suggest that an acute oral dose of bis selenide produced an antidepressant-like effect in the mouse TST by a mechanism that involves the K(+) channels and PPARγ receptors.

  17. Metabolism and functions of copper in brain.

    PubMed

    Scheiber, Ivo F; Mercer, Julian F B; Dringen, Ralf

    2014-05-01

    Copper is an important trace element that is required for essential enzymes. However, due to its redox activity, copper can also lead to the generation of toxic reactive oxygen species. Therefore, cellular uptake, storage as well as export of copper have to be tightly regulated in order to guarantee sufficient copper supply for the synthesis of copper-containing enzymes but also to prevent copper-induced oxidative stress. In brain, copper is of importance for normal development. In addition, both copper deficiency as well as excess of copper can seriously affect brain functions. Therefore, this organ possesses ample mechanisms to regulate its copper metabolism. In brain, astrocytes are considered as important regulators of copper homeostasis. Impairments of homeostatic mechanisms in brain copper metabolism have been associated with neurodegeneration in human disorders such as Menkes disease, Wilson's disease and Alzheimer's disease. This review article will summarize the biological functions of copper in the brain and will describe the current knowledge on the mechanisms involved in copper transport, storage and export of brain cells. The role of copper in diseases that have been connected with disturbances in brain copper homeostasis will also be discussed.

  18. 21 CFR 73.1647 - Copper powder.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Copper powder. 73.1647 Section 73.1647 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1647 Copper powder. (a) Identity. (1) The color additive copper powder is a very fine free-flowing metallic powder prepared from virgin electrolytic copper....

  19. 21 CFR 73.1647 - Copper powder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Copper powder. 73.1647 Section 73.1647 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1647 Copper powder. (a) Identity. (1) The color additive copper powder is a very fine free-flowing metallic powder prepared from virgin electrolytic copper....

  20. 49 CFR 192.279 - Copper pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Copper pipe. 192.279 Section 192.279 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Copper pipe. Copper pipe may not be threaded except that copper pipe used for joining screw fittings...

  1. 49 CFR 192.279 - Copper pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Copper pipe. 192.279 Section 192.279 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Copper pipe. Copper pipe may not be threaded except that copper pipe used for joining screw fittings...

  2. 21 CFR 73.1647 - Copper powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Copper powder. 73.1647 Section 73.1647 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1647 Copper powder. (a) Identity. (1) The color additive copper powder is a very fine free-flowing metallic powder prepared from virgin electrolytic copper....

  3. 21 CFR 184.1260 - Copper gluconate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Copper gluconate. 184.1260 Section 184.1260 Food... GRAS § 184.1260 Copper gluconate. (a) Copper gluconate (cupric gluconate (CH2OH(CHOH)4COO)2Cu, CAS Reg... ingredient is used in food at levels not to exceed current good manufacturing practice. Copper gluconate...

  4. 21 CFR 184.1260 - Copper gluconate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Copper gluconate. 184.1260 Section 184.1260 Food... Specific Substances Affirmed as GRAS § 184.1260 Copper gluconate. (a) Copper gluconate (cupric gluconate... practice. Copper gluconate may be used in infant formula in accordance with section 412(g) of the...

  5. 21 CFR 184.1260 - Copper gluconate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Copper gluconate. 184.1260 Section 184.1260 Food... Specific Substances Affirmed as GRAS § 184.1260 Copper gluconate. (a) Copper gluconate (cupric gluconate... practice. Copper gluconate may be used in infant formula in accordance with section 412(g) of the...

  6. 21 CFR 184.1260 - Copper gluconate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Copper gluconate. 184.1260 Section 184.1260 Food... Specific Substances Affirmed as GRAS § 184.1260 Copper gluconate. (a) Copper gluconate (cupric gluconate... practice. Copper gluconate may be used in infant formula in accordance with section 412(g) of the...

  7. 49 CFR 192.279 - Copper pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Copper pipe. 192.279 Section 192.279 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Copper pipe. Copper pipe may not be threaded except that copper pipe used for joining screw fittings...

  8. 21 CFR 184.1260 - Copper gluconate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Copper gluconate. 184.1260 Section 184.1260 Food... Specific Substances Affirmed as GRAS § 184.1260 Copper gluconate. (a) Copper gluconate (cupric gluconate... practice. Copper gluconate may be used in infant formula in accordance with section 412(g) of the...

  9. 49 CFR 192.279 - Copper pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Copper pipe. 192.279 Section 192.279 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Copper pipe. Copper pipe may not be threaded except that copper pipe used for joining screw fittings...

  10. 21 CFR 73.1647 - Copper powder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Copper powder. 73.1647 Section 73.1647 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1647 Copper powder. (a) Identity. (1) The color additive copper powder is a very fine free-flowing metallic powder prepared from virgin electrolytic copper....

  11. 49 CFR 192.279 - Copper pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Copper pipe. 192.279 Section 192.279 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Copper pipe. Copper pipe may not be threaded except that copper pipe used for joining screw fittings...

  12. Effect of an iodine-containing additive on the composition, structure, and morphology of chemically deposited lead selenide films

    NASA Astrophysics Data System (ADS)

    Smirnova, Z. I.; Bakanov, V. M.; Maskaeva, L. N.; Markov, V. F.; Voronin, V. I.

    2014-12-01

    The effect of an ammonium iodide additive on the elemental and phase compositions, structural parameters, and surface morphology of lead selenide films synthesized by chemical deposition from aqueous solutions has been studied using X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray analysis. It has been established that the obtained PbSe films have a multiphase structure. The iodine content of the films is directly proportional to the NH4I concentration in the reaction mixture and increases linearly with an increase in this concentration to 0.25 mol/L. No individual iodine-containing phases have been detected in the film structure. However, the introduction of iodine leads to an increase in the PbSe phase lattice parameter from ˜6.11 to ˜6.16 Å and to a decrease in the crystal grain size to ˜ 20 nm. It has been found that there is a correlation between the grain size, lattice parameter, and ammonium iodide concentration in the reaction mixture, which can be explained by changes in the film growth mechanism at the initial growth steps.

  13. Electrical Transport and Grain Growth in Solution-Cast, Chloride-Terminated Cadmium Selenide Nanocrystal Thin Films

    PubMed Central

    2015-01-01

    We report the evolution of electrical transport and grain size during the sintering of thin films spin-cast from soluble phosphine and amine-bound, chloride-terminated cadmium selenide nanocrystals. Sintering of the nanocrystals occurs in three distinct stages as the annealing temperature is increased: (1) reversible desorption of the organic ligands (≤150 °C), (2) irreversible particle fusion (200–300 °C), and (3) ripening of the grains to >5 nm domains (>200 °C). Grain growth occurs at 200 °C in films with 8 atom % Cl–, while films with 3 atom % Cl– resist growth until 300 °C. Fused nanocrystalline thin films (grain size = 4.5–5.5 nm) on thermally grown silicon dioxide gate dielectrics produce field-effect transistors with electron mobilities as high as 25 cm2/(Vs) and on/off ratios of 105 with less than 0.5 V hysteresis in threshold voltage without the addition of indium. PMID:24960255

  14. Reduction of elemental selenium to selenide: Experiments with anoxic sediments and bacteria that respire Se-oxyanions

    USGS Publications Warehouse

    Herbel, M.J.; Blum, J.S.; Oremland, R.S.; Borglin, S.E.

    2003-01-01

    A selenite-respiring bacterium, Bacillus selenitireducens, produced significant levels of Se(-II) (as aqueous HSe-) when supplied with Se(O). B. selenitireducens was also able to reduce selenite [Se(IV)] through Se(O) to Se(-II). Reduction of Se(O) by B.selenitireducens was more rapid in cells grown on colloidal sulfur [S(O)] or Se(IV) as their electron acceptor than for cell lines grown on fumarate. In contrast, three cultures of selenate-respiring bacteria, Sulfurospirillum barnesii, B. arsenicoselenatis, and Selenihalanaerobacter shriftii either were unable to reduce Se(O) to Se(-II) or had only a very limited capacity to achieve this reduction. Biological reduction of Se(O) to Se(-II) was observed during incubation of estuarine sediment slurries, while no such activity was noted in formalin-killed controls. The majority of the Se(-II) produced was found in the sediments as a solid precipitate of FeSe, rather than in solution as HSe-. These results demonstrate that certain anaerobic bacteria have the capacity to reduce Se(O) to Se(-II), providing a possible biological explanation for the occurrence of the selenide species in some sedimentary rocks.

  15. An in vitro assessment of the interaction of cadmium selenide quantum dots with DNA, iron, and blood platelets.

    PubMed

    Dunpall, Rekha; Nejo, Adeola Ayodeji; Pullabhotla, Viswanadha Srirama Rajasekhar; Opoku, Andy R; Revaprasadu, Neerish; Shonhai, Addmore

    2012-12-01

    Cadmium selenide (CdSe) quantum dots have gained increased attention for their potential use in biomedical applications. This has raised interest in assessing their toxicity. In this study, water-soluble, cysteine-capped CdSe nanocrystals with an average size of 15 nm were prepared through a one-pot solution-based method. The CdSe nanoparticles were synthesized in batches in which the concentration of the capping agent was varied with the aim of stabilizing the quantum dot core. The effects of the CdSe quantum dots on DNA stability, aggregation of blood platelets, and reducing activity of iron were evaluated in vitro . DNA damage was observed at a concentration of 200 μg/mL of CdSe quantum dots. Furthermore, the CdSe nanocrystals exhibited high reducing power and chelating activity, suggesting that they may impair the function of haemoglobin by interacting with iron. In addition, the CdSe quantum dots promoted aggregation of blood platelets in a dose dependent manner.

  16. Electric double-layer transistor using layered iron selenide Mott insulator TlFe1.6Se2

    PubMed Central

    Katase, Takayoshi; Hiramatsu, Hidenori; Kamiya, Toshio; Hosono, Hideo

    2014-01-01

    A1–xFe2–ySe2 (A = K, Cs, Rb, Tl) are recently discovered iron-based superconductors with critical temperatures (Tc) ranging up to 32 K. Their parent phases have unique properties compared with other iron-based superconductors; e.g., their crystal structures include ordered Fe vacancies, their normal states are antiferromagnetic (AFM) insulating phases, and they have extremely high Néel transition temperatures. However, control of carrier doping into the parent AFM insulators has been difficult due to their intrinsic phase separation. Here, we fabricated an Fe-vacancy-ordered TlFe1.6Se2 insulating epitaxial film with an atomically flat surface and examined its electrostatic carrier doping using an electric double-layer transistor (EDLT) structure with an ionic liquid gate. The positive gate voltage gave a conductance modulation of three orders of magnitude at 25 K, and further induced and manipulated a phase transition; i.e., delocalized carrier generation by electrostatic doping is the origin of the phase transition. This is the first demonstration, to the authors' knowledge, of an EDLT using a Mott insulator iron selenide channel and opens a way to explore high Tc superconductivity in iron-based layered materials, where carrier doping by conventional chemical means is difficult. PMID:24591598

  17. Ultrasensitive electrochemical biosensing platform based on spherical silicon dioxide/molybdenum selenide nanohybrids and triggered Hybridization Chain Reaction.

    PubMed

    Shuai, Hong-Lei; Wu, Xu; Huang, Ke-Jing; Zhai, Zi-Bo

    2017-03-30

    An ultrasensitive sandwich-type electrochemical biosensor for DNA detection is developed based on spherical silicon dioxide/molybdenum selenide (SiO2@MoSe2) and graphene oxide-gold nanoparticles (GO-AuNPs) hybrids as carrier triggered Hybridization Chain Reaction (HCR) coupling with multi-signal amplification. The proposed sensoring assay utilizes a spherical SiO2@MoSe2/AuNPs as sensing platform and GO-AuNPs hybrids as carriers to supply vast binding sites. H2O2+HQ system is used for DNA detection and HCR as the signal and selectivity enhancer. The sensor is designed in sandwich type to increase the specificity. As a result, the present biosensor exhibits a good dynamic range from 0.1fM to 100pM with a low detection limit of 0.068fM (S/N=3). This work shows a considerable potential for quantitative detection of DNA in early clinical diagnostics.

  18. Remarkable photo-catalytic degradation of malachite green by nickel doped bismuth selenide under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Kulsi, Chiranjit; Ghosh, Amrita; Mondal, Anup; Kargupta, Kajari; Ganguly, Saibal; Banerjee, Dipali

    2017-01-01

    Bismuth selenide (Bi2Se3) and nickel (Ni) doped Bi2Se3 were prepared by a solvothermal approach to explore the photo-catalytic performance of the materials in degradation of malachite green (MG). The presence of nickel was confirmed by X-ray photoelectron spectroscopy (XPS) measurement in doped Bi2Se3. The results showed that the nickel doping played an important role in microstructure and photo-catalytic activity of the samples. Nickel doped Bi2Se3 sample exhibited higher photo-catalytic activity than that of the pure Bi2Se3 sample under visible-light irradiation. The photo-catalytic degradation followed first-order reaction kinetics. Fast degradation kinetics and complete (100% in 5 min of visible light irradiation) removal of MG was achieved by nickel doped Bi2Se3 in presence of hydrogen peroxide (H2O2) due to modification of band gap energies leading to suppression of photo-generated electron-hole recombination.

  19. Aspects of a Distinct Cytotoxicity of Selenium Salts and Organic Selenides in Living Cells with Possible Implications for Drug Design.

    PubMed

    Estevam, Ethiene Castellucci; Witek, Karolina; Faulstich, Lisa; Nasim, Muhammad Jawad; Latacz, Gniewomir; Domínguez-Álvarez, Enrique; Kieć-Kononowicz, Katarzyna; Demasi, Marilene; Handzlik, Jadwiga; Jacob, Claus

    2015-07-31

    Selenium is traditionally considered as an antioxidant element and selenium compounds are often discussed in the context of chemoprevention and therapy. Recent studies, however, have revealed a rather more colorful and diverse biological action of selenium-based compounds, including the modulation of the intracellular redox homeostasis and an often selective interference with regulatory cellular pathways. Our basic activity and mode of action studies with simple selenium and tellurium salts in different strains of Staphylococcus aureus (MRSA) and Saccharomyces cerevisiae indicate that such compounds are sometimes not particularly toxic on their own, yet enhance the antibacterial potential of known antibiotics, possibly via the bioreductive formation of insoluble elemental deposits. Whilst the selenium and tellurium compounds tested do not necessarily act via the generation of Reactive Oxygen Species (ROS), they seem to interfere with various cellular pathways, including a possible inhibition of the proteasome and hindrance of DNA repair. Here, organic selenides are considerably more active compared to simple salts. The interference of selenium (and tellurium) compounds with multiple targets could provide new avenues for the development of effective antibiotic and anticancer agents which may go well beyond the traditional notion of selenium as a simple antioxidant.

  20. Loading of atorvastatin and linezolid in β-cyclodextrin-conjugated cadmium selenide/silica nanoparticles: A spectroscopic study.

    PubMed

    Antony, Eva Janet; Shibu, Abhishek; Ramasamy, Sivaraj; Paulraj, Mosae Selvakumar; Enoch, Israel V M V

    2016-08-01

    The preparation of β-cyclodextrin-conjugated cadmium selenide-silica nanoparticles, the loading of two drugs viz., Atorvastatin and linezolid in the cyclodextrin cavity, and the fluorescence energy transfer between CdSe/SiO2 nanoparticles and the drugs encapsulated in the cyclodextrin cavity are reported in this paper. IR spectroscopy, X-ray diffractometry, transmission electron microscopy, and particle size analysis by light-scattering experiment were used as the tools of characterizing the size and the crystal system of the nanoparticles. The nanoparticles fall under hexagonal system. The silica-shell containing CdSe nanoparticles were functionalized by reaction with aminoethylamino-β-cyclodextrin. Fluorescence spectra of the nanoparticles in their free and drug-encapsulated forms were studied. The FÖrster distances between the encapsulated drugs and the CdSe nanoparticles are below 3nm. The change in the FÖrster resonance energy parameters under physiological conditions may aid in tracking the release of drugs from the cavity of the cyclodextrin.

  1. Digital radiology using active matrix readout of amorphous selenium: radiation hardness of cadmium selenide thin film transistors.

    PubMed

    Zhao, W; Waechter, D; Rowlands, J A

    1998-04-01

    A flat-panel x-ray imaging detector using active matrix readout of amorphous selenium (a-Se) is being investigated for digital radiography and fluoroscopy. The active matrix consists of a two-dimensional array of thin film transistors (TFTs). Radiation penetrating through the a-Se layer will interact with the TFTs and it is important to ensure that radiation induced changes will not affect the operation of the x-ray imaging detector. The methodology of the present work is to investigate the effects of radiation on the characteristic curves of the TFTs using individual TFT samples made with cadmium selenide (CdSe) semiconductor. Four characteristic parameters, i.e., threshold voltage, subthreshold swing, field effect mobility, and leakage current, were examined. This choice of parameters was based on the well established radiation damage mechanisms for crystalline silicon metal-oxide-semiconductor field-effect transistors (MOSFETs), which have a similar principle of operation as CdSe TFTs. It was found that radiation had no measurable effect on the leakage current and the field effect mobility. However, radiation shifted the threshold voltage and increased the subthreshold swing. But even the estimated lifetime dose (50 Gy) of a diagnostic radiation detector will not affect the normal operation of an active matrix x-ray detector made with CdSe TFTs. The mechanisms of the effects of radiation will be discussed and compared with those for MOSFETs and hydrogenated amorphous silicon (a-Si:H) TFTs.

  2. Simultaneous Determination of Adenine and Guanine Using Cadmium Selenide Quantum Dots-Graphene Oxide Nanocomposite Modified Electrode.

    PubMed

    Kalaivani, Arumugam; Narayanan, Sangilimuthu Sriman

    2015-06-01

    A novel electrochemical sensor was fabricated by immobilizing Cadmium Selenide Quantum Dots (CdSe QDs)-Graphene Oxide (GO) nanocomposite on a paraffin wax impregnated graphite electrode (PIGE) and was used for the simultaneous determination of adenine and guanine. The CdSe QDs-GO nanocomposite was prepared by ultrasonication and was characterized with spectroscopic and microscopic techniques. The nanocomposite modified electrode was characterized by cyclic voltammetry (CV). The modified electrode showed excellent electrocatalytic activity towards the oxidative determination of adenine and guanine with a good peak separation of 0.31 V. This may be due to the high surface area and fast electron transfer kinetics of the nanocomposite. The modified electrode exhibited wide linear ranges from 0.167 μM to 245 μM for Guanine and 0.083 μM to 291 μM for Adenine with detection limits of 0.055 μM Guanine and 0.028 μM of Adenine (S/N = 3) respectively. Further, the modified electrode was used for the quantitative determination of adenine and guanine in herring sperm DNA with satisfactory results. The modified electrode showed acceptable selectivity, reproducibility and stability under optimal conditions.

  3. Electrical transport and grain growth in solution-cast, chloride-terminated cadmium selenide nanocrystal thin films.

    PubMed

    Norman, Zachariah M; Anderson, Nicholas C; Owen, Jonathan S

    2014-07-22

    We report the evolution of electrical transport and grain size during the sintering of thin films spin-cast from soluble phosphine and amine-bound, chloride-terminated cadmium selenide nanocrystals. Sintering of the nanocrystals occurs in three distinct stages as the annealing temperature is increased: (1) reversible desorption of the organic ligands (≤150 °C), (2) irreversible particle fusion (200-300 °C), and (3) ripening of the grains to >5 nm domains (>200 °C). Grain growth occurs at 200 °C in films with 8 atom % Cl(-), while films with 3 atom % Cl(-) resist growth until 300 °C. Fused nanocrystalline thin films (grain size = 4.5-5.5 nm) on thermally grown silicon dioxide gate dielectrics produce field-effect transistors with electron mobilities as high as 25 cm(2)/(Vs) and on/off ratios of 10(5) with less than 0.5 V hysteresis in threshold voltage without the addition of indium.

  4. Photochemical fine-tuning of luminescent color of cadmium selenide nanoparticles: fabricating a single-source multicolor luminophore.

    PubMed

    Torimoto, Tsukasa; Murakami, Shin-ya; Sakuraoka, Miwa; Iwasaki, Kentaro; Okazaki, Ken-ichi; Shibayama, Tamaki; Ohtani, Bunsho

    2006-07-13

    Size-selective photoetching was applied to silica-coated cadmium selenide (SiO2/CdSe) nanoparticles to precisely control their photoluminescence properties. The absorption spectra of CdSe was blue-shifted by irradiation of monochromatic light, and finally, the absorption onset agreed with the wavelength of irradiation light, indicating that CdSe particles were photoetched to smaller ones until the irradiated photons were not absorbed by the photoetched particles and that the SiO2 shell layer surrounding the CdSe core prevented coalescence between the photoetched particles. Although as-prepared SiO2/CdSe did not exhibit photoluminescence, the application of size-selective photoetching to SiO2/CdSe resulted in the development of the band gap emission, with the degree being enhanced with progress of the photoetching. The peak wavelength of photoluminescence decreased with a decrease in the wavelength used for the photoetching, so that the luminescence color could be tuned between red and blue. Partial photoetching of SiO2/CdSe nanoparticle films produced intense band gap emission of CdSe at the photoetched area, while the remainder of the SiO2/CdSe films did not exhibit detectable photoluminescence, resulting in the formation of a clear photoluminescence image under UV irradiation. This technique makes it possible to produce a multicolored photoluminescence image by irradiation with monochromatic lights having various wavelengths using a single source material.

  5. Selecting copper and copper alloys; Part 2: Cast products

    SciTech Connect

    Peters, D.T. ); Kundig, K.J.A. , Randolph, NJ )

    1994-06-01

    This article provides an introduction to the properties, characteristics, and applications of cast coppers and copper alloys. An overview of alloy families is presented since it is impractical to describe all 130 standard grades in detail. However, additional technical information is readily available from the Copper Development Assn. Inc. (CDA) and the resources listed in the references and bibliography at the end of the article. Copper casting alloys are primarily selected for either their corrosion resistance, or their combination of corrosion resistance and mechanical properties. The materials also feature good castability, high machinability, and, compared with other corrosion-resistant alloys, reasonable cost. Additional benefits include biofouling resistance--important in marine applications--and a spectrum of attractive colors. Many of the alloys also have favorable tribological properties, which explains their widespread use for sleeve bearings, wear plates, gears, and other wear-prone components.

  6. Solvent-controlled halo-selective selenylation of aryl halides catalyzed by Cu(II) supported on Al2O3. A general protocol for the synthesis of unsymmetrical organo mono- and bis-selenides.

    PubMed

    Chatterjee, Tanmay; Ranu, Brindaban C

    2013-07-19

    Alumina-supported Cu(II) efficiently catalyzes selenylation of aryl iodides and aryl bromides by diaryl, dialkyl, and diheteroaryl diselenides in water and PEG-600, respectively, leading to a general route toward synthesis of unsymmetrical diaryl, aryl-alkyl, aryl-heteroaryl, and diheteroaryl selenides. A sequential reaction of bromoiodobenzene with one diaryl/diheteroaryl/dialkyl diselenide in water and another diaryl/diheteroaryl/dialkyl diselenide in PEG-600 in the second step produces unsymmetrical diaryl, diheteroaryl, or aryl-alkyl bis-selanyl benzene. A library of functionalized organo mono- and bis-selenides, including a potent biologically active molecule and a couple of analogues of bioactive selenides, were obtained in high yields by this protocol. The reactions are chemoselective and high yielding. The Cu-Al2O3 catalyst is recycled for seven runs without any appreciable loss of activity.

  7. Interpulse kinetics in copper and copper halide lasers

    NASA Technical Reports Server (NTRS)

    Harstad, K. G.

    1983-01-01

    The various rate processes that govern the interpulse relaxation in metal vapor and metal halide vapor lasers are considered. Computer calculations indicate that the rapid metastable levels relaxation observed in copper and copper halide laser experiments requires the existence of a relatively small resonance in the cross section for metastable excitation or deexcitation near threshold. The accurate calculation of interpulse relaxation requires knowledge of rate constants presently not well known; this is especially so for metal halide lasers.

  8. Majorana Electroformed Copper Mechanical Analysis

    SciTech Connect

    Overman, Nicole R.; Overman, Cory T.; Kafentzis, Tyler A.; Edwards, Danny J.; Hoppe, Eric W.

    2012-04-30

    The MAJORANA DEMONSTRATOR is a large array of ultra-low background high-purity germanium detectors, enriched in 76Ge, designed to search for zero-neutrino double-beta decay. The DEMONSTRATOR will utilize ultra high purity electroformed copper for a variety of detector components and shielding. A preliminary mechanical evaluation was performed on the Majorana prototype electroformed copper material. Several samples were removed from a variety of positions on the mandrel. Tensile testing, optical metallography, scanning electron microscopy, and hardness testing were conducted to evaluate mechanical response. Analyses carried out on the Majorana prototype copper to this point show consistent mechanical response from a variety of test locations. Evaluation shows the copper meets or exceeds the design specifications.

  9. Copper atomic-scale transistors

    PubMed Central

    Kavalenka, Maryna N; Röger, Moritz; Albrecht, Daniel; Hölscher, Hendrik; Leuthold, Jürgen

    2017-01-01

    We investigated copper as a working material for metallic atomic-scale transistors and confirmed that copper atomic-scale transistors can be fabricated and operated electrochemically in a copper electrolyte (CuSO4 + H2SO4) in bi-distilled water under ambient conditions with three microelectrodes (source, drain and gate). The electrochemical switching-on potential of the atomic-scale transistor is below 350 mV, and the switching-off potential is between 0 and −170 mV. The switching-on current is above 1 μA, which is compatible with semiconductor transistor devices. Both sign and amplitude of the voltage applied across the source and drain electrodes (U bias) influence the switching rate of the transistor and the copper deposition on the electrodes, and correspondingly shift the electrochemical operation potential. The copper atomic-scale transistors can be switched using a function generator without a computer-controlled feedback switching mechanism. The copper atomic-scale transistors, with only one or two atoms at the narrowest constriction, were realized to switch between 0 and 1G 0 (G 0 = 2e2/h; with e being the electron charge, and h being Planck’s constant) or 2G 0 by the function generator. The switching rate can reach up to 10 Hz. The copper atomic-scale transistor demonstrates volatile/non-volatile dual functionalities. Such an optimal merging of the logic with memory may open a perspective for processor-in-memory and logic-in-memory architectures, using copper as an alternative working material besides silver for fully metallic atomic-scale transistors. PMID:28382242

  10. Antinociceptive effect of butyl (2-phenylethynyl) selenide on formalin test in mice: Evidences for the involvement of serotonergic and adenosinergic systems.

    PubMed

    Luchese, Cristiane; Prigol, Marina; Acker, Carmine Inês; Nogueira, Cristina Wayne

    2010-10-10

    The present study investigated the effect of per oral (p.o.) administration of butyl (2-phenylethynyl) selenide (1-50mg/kg) on formalin-induced nociception in mice. The involvement of serotonergic, adenosinergic, muscarinic cholinergic and opioid mechanisms in the antinociceptive effect was also investigated. Butyl (2-phenylethynyl) selenide inhibited both neurogenic (at doses equal or higher than 10mg/kg) and inflammatory (at doses equal or higher than 25mg/kg) phases of the nociception caused by intraplantar (i.pl.) injection of 2.5% formalin solution (20 microl), with ID(50) values of 36.7 (29.28-46.0) and 20.37 (15.74-26.36) mg/kg, respectively. This compound reduced the formalin-induced paw oedema formation (55 + or - 4%) at doses equal or higher than 25mg/kg. The antinociceptive effect of compound (25mg/kg, p.o.) was reversed by ondansetron (0.5mg/kg, a 5-HT(3) receptor antagonist) and caffeine (3mg/kg, a nonselective adenosine receptor antagonist), but not by atropine (0.1mg/kg, a non selective muscarinic antagonist), WAY100635 (0.1mg/kg, a selective 5-HT(1A) receptor antagonist), ritanserin (1mg/kg, a 5-HT(2) receptor antagonist) and naloxone (1mg/kg, a non selective opioid receptor antagonist). These results indicate that butyl (2-phenylethynyl) selenide produced antinociception in the formalin test through mechanisms that involve an interaction with serotonergic (5-HT(3)) and adenosinergic systems.

  11. Metal selenides as a new class of electrocatalysts for quantum dot-sensitized solar cells: a tale of Cu(1.8)Se and PbSe.

    PubMed

    Choi, Hye Mi; Ji, In Ae; Bang, Jin Ho

    2014-02-26

    The development of a Pt-free, highly active electrocatalyst for a counter electrode (CE) is vital to the construction of highly efficient quantum dot-sensitized solar cells (QDSSCs). As an alternative to Pt, the use of various metal sulfides, such as Cu2S, CoS, and PbS, has been successfully demonstrated; however, the studies on the utilization of non-sulfide materials have been scarcely reported. In this regard, we examined eight different types of binary metal selenides as new candidate materials, and found that the electrocatalytic activity of Cu1.8Se and PbSe toward polysulfide reduction was superior to that of Pt. In depth investigation into these two materials further revealed that, while the electrocatalytic activity of both metal selenides surpasses that of Pt, the long-term utilization of the PbSe CE is hindered by the formation of PbO on the surface of PbSe, which is attributed to the instability of PbSe under air. Unlike PbSe, Cu1.8Se was found to be chemically stable with a polysulfide electrolyte and was even better than Cu2S, a commonly used CE material for QDSSCs. Using the Cu1.8Se CE, we obtained a power conversion efficiency of 5.0% for CdS/CdSe-sensitized solar cells, which was an efficiency almost twice that obtained from Pt CE. This work provides a new application for metal selenides, which have been traditionally utilized as sensitizers for QDSSCs.

  12. Transition-Metal-Free Diarylannulated Sulfide and Selenide Construction via Radical/Anion-Mediated Sulfur-Iodine and Selenium-Iodine Exchange.

    PubMed

    Wang, Ming; Fan, Qiaoling; Jiang, Xuefeng

    2016-11-04

    A facile, straightforward protocol was established for diarylannulated sulfide and selenide construction through S-I and Se-I exchange without transition metal assistance. Elemental sulfur and selenium served as the chalcogen source. Diarylannulated sulfides were systematically achieved from a five- to eight-membered ring. A trisulfur radical anion was demonstrated as the initiator for this radical process via electron paramagnetic resonance (EPR) study. OFET molecules [1]benzothieno[3,2-b][1]benzothiophene (BTBT) and [1]benzothieno[3,2-b][1]benzoselenophene (BTBS) were efficiently established.

  13. Synthesis, crystal structure and second-order nonlinear optical property of a novel pentanary selenide (K3I)[InB12(InSe4)3].

    PubMed

    Guo, Sheng-Ping; Chi, Yang; Liu, Bin-Wen; Guo, Guo-Cong

    2016-06-21

    A novel pentanary selenide (K3I)[InB12(InSe4)3] was obtained via a high-temperature solid-state method. It crystallizes in the hexagonal space group P6322 which features an InSe4 tetrahedron consolidated B12 icosahedron and 1-D chain constructed by InSe6 octahedron and B12Se12 cluster alternatively connected along the c-axis. Second-order nonlinear optical property measurement shows that it is second harmonic generation-active. Theory calculation indicates that it is an indirect semiconductor with the energy gap of 1.15 eV.

  14. Continuously tunable, 6{endash}14 {mu}m silver-gallium selenide optical parametric oscillator pumped at 1.57 {mu}m

    SciTech Connect

    Chandra, S.; Allik, T.H.; Catella, G.; Utano, R.; Hutchinson, J.A.

    1997-08-01

    An angle tuned silver gallium selenide (AgGaSe{sub 2}) optical parametric oscillator (OPO), pumped by the fixed wavelength 1.57 {mu}m output of a noncritically phase-matched KTiOPO{sub 4} OPO, yielded radiation continuously tunable from 6 to 14 {mu}m. Energies of up to 1.2 mJ/pulse with bandwidths of {approximately}5cm{sup {minus}1} (full width at half-maximum) were obtained using a 6.5{times}6.5{times}35.3mm long, type I AgGaSe{sub 2} crystal. {copyright} {ital 1997 American Institute of Physics.}

  15. Release of Micronized Copper Particles from Pressure ...

    EPA Pesticide Factsheets

    Micronized copper pressure treated lumber (PTL) has recently been introduced to the consumer market as a replacement for ionized copper PTL. The presence of particulate rather than aqueous copper raises concerns about the exposure of humans as well as the environment to the particles. Two common pathways of exposure, leaching during contact with water and transfer during physical contact, were investigated to gage potential human and environmental risk during intended use of the product. Characterization, leaching tests, and wipe tests were conducted on two representative formulations of micronized copper PTL (micronized copper azole or MCA) to quantify the levels of copper present in the treated material and the amount of copper released during use as well as to determine the form (particle or ion) of the copper after it was released. Additionally, an ionized copper pressure treated wood (alkaline copper azole or ACA) was tested for comparison. The characterization showed that copper carbonate is the primary particle form in the MCA treated wood, but other forms are also present, particularly in the MCA-1 formulation, which contained a large amount of organically complexed copper. Microscopy showed that MCA-1 contained particles roughly half the size of MCA-2. The leaching results indicate that mostly (> ~95%) ionic copper is released from the MCA wood and that the particulate copper that was released is attached to cellulose and not free in solution. A sma

  16. Copper status of ewes fed increasing amounts of copper from copper sulfate or copper proteinate.

    PubMed

    Eckert, G E; Greene, L W; Carstens, G E; Ramsey, W S

    1999-01-01

    The Cu status of mature, crossbred ewes fed two sources (CuSO4 vs. Cu proteinate) and three levels (10, 20, or 30 mg/kg) of dietary Cu was determined in a 73-d feeding trial. Ewes (n = 30) were fed a basal diet containing rice meal feed, cottonseed hulls, cottonseed meal, meat and bone meal, cracked corn, and vitamin-mineral supplements at 2.5% of BW to meet NRC requirements for protein, energy, macrominerals, and microminerals, excluding Cu. The basal diet contained 5 mg/kg Cu, 113 mg/kg Fe, .1 mg/kg Mo, and .17% S. Copper sulfate or Cu proteinate was added to the basal diet to supply 10, 20, or 30 mg/kg of dietary copper in a 2x3 factorial arrangement of treatments. Ewes were housed in 3.7- x 9.1-m pens in an open-sided barn. Blood samples were collected on d 28 and 73. Ewes were slaughtered on d 74, and liver and other tissues were collected to determine Cu concentrations. An interaction (P = .08) occurred between source and level for liver Cu. The interaction existed due to an increase in liver Cu concentrations when ewes were fed increasing dietary Cu from CuSO4 but not when fed Cu proteinate diets. There was no source x level interaction (P>.10) for the blood constituents measured. On d 73, plasma ceruloplasmin activity was greater (P<.05) in ewes fed Cu proteinate than in those fed CuSO4 (33.1 vs. 26.8 microM x min(-1) x L(-1)). Increasing the concentration of dietary Cu did not affect (P>.10) plasma ceruloplasmin. Packed cell volume (PCV), red blood cell count (RBC), white blood cell count, whole blood hemoglobin (wHb), plasma hemoglobin, and plasma Cu were similar between sources of Cu. Ewes fed 20 mg/kg Cu had lower (P<.05) PCV, RBC, and wHb than those fed 10 or 30 mg/kg Cu diets. Feeding up to 30 mg/kg Cu from these sources did not cause an observable Cu toxicity during the 73-d period.

  17. Genes involved in copper resistance influence survival of Pseudomonas aeruginosa on copper surfaces

    PubMed Central

    Elguindi, Jutta; Wagner, Janine; Rensing, Christopher

    2013-01-01

    Aims To evaluate the killing of Pseudomonas aeruginosa PAO1 on copper cast alloys and the influence of genes on survival on copper containing medium and surfaces. Methods and Results Different strains of P. aeruginosa were inoculated on copper containing medium or different copper cast alloys and the survival rate determined. The survival rates were compared to rates on copper-free medium and stainless steel as control. In addition, the effect of temperature on survival was examined. Conclusions Copper cast alloys had previously shown to be bactericidal to various bacteria but the mechanism of copper-mediated killing is still not known. In this report we demonstrate that P. aeruginosa PAO1 is rapidly killed on different copper cast alloys and that genes involved in conferring copper resistance in copper-containing medium also influenced survival on copper cast alloys. We also show that the rate of killing is influenced by temperature. PMID:19239551

  18. Physical and biophysical assessment of highly fluorescent, magnetic quantum dots of a wurtzite-phase manganese selenide system

    NASA Astrophysics Data System (ADS)

    Sarma, Runjun; Das, Queen; Hussain, Anowar; Ramteke, Anand; Choudhury, Amarjyoti; Mohanta, Dambarudhar

    2014-07-01

    Combining fluorescence and magnetic features in a non-iron based, select type of quantum dots (QDs) can have immense value in cellular imaging, tagging and other nano-bio interface applications, including targeted drug delivery. Herein, we report on the colloidal synthesis and physical and biophysical assessment of wurtzite-type manganese selenide (MnSe) QDs in cell culture media. Aiming to provide a suitable colloidal system of biological relevance, different concentrations of reactants and ligands (e.g., thioglycolic acid, TGA) have been considered. The average size of the QDs is ˜7 nm, which exhibited a quantum yield of ˜75% as compared to rhodamine 6 G dye®. As revealed from time-resolved photoluminescence (TR-PL) response, the near band edge emission followed a bi-exponential decay feature with characteristic times of ˜0.64 ns and 3.04 ns. At room temperature, the QDs were found to exhibit paramagnetic features with coercivity and remanence impelled by TGA concentrations. With BSA as a dispersing agent, the QDs showed an improved optical stability in Dulbecco’s Modified Eagle Media® (DMEM) and Minimum Essential Media® (MEM), as compared to the Roswell Park Memorial Institute® (RPMI-1640) media. Finally, the cell viability of lymphocytes was found to be strongly influenced by the concentration of MnSe QDs, and had a safe limit upto 0.5 μM. With BSA inclusion in cell media, the cellular uptake of MnSe QDs was observed to be more prominent, as revealed from fluorescence imaging. The fabrication of water soluble, nontoxic MnSe QDs would open up an alternative strategy in nanobiotechnology, while preserving their luminescent and magnetic properties intact.

  19. Theoretical investigation of electronic states and spectroscopic properties of tellurium selenide molecule employing relativistic effective core potentials.

    PubMed

    Chattopadhyaya, Surya; Nath, Abhijit; Das, Kalyan Kumar

    2014-04-24

    Ab initio based relativistic configuration interaction calculations have been performed to study the electronic states and spectroscopic properties of tellurium selenide (TeSe) - the heaviest heteronuclear diatomic group 16-16 molecule. Potential energy curves of several spin-excluded (Λ-S) electronic states of TeSe have been constructed and spectroscopic constants of low-lying bound Λ-S states within 3.85 eV are reported in the first stage of calculations. The X(3)Σ(-), a(1)Δ and b(1)Σ(+) are found as the ground, first excited and second excited state, respectively, at the Λ-S level and all these three states are mainly dominated by …π(4)π(*2) configuration. The computed ground state dissociation energy is in very good agreement with the experimental results. In the next stage of calculations, effects of spin-orbit coupling on the potential energy curves and spectroscopic properties of the species are investigated in details and compared with the existing experimental results. After inclusion of spin-orbit coupling the X(3)(1)Σ(-)(0(+)) is found as the ground-state spin component of TeSe. The computed spin-orbit splitting between two components of X(3)Σ(-) state is 1285 cm(-1). Also, significant amount of spin-orbit splitting are found between spin-orbit components (Ω-components) of several other excited states. Transition moments of some important spin-allowed and spin-forbidden transitions are calculated from configuration interaction wave functions. The spin-allowed transition B(3)Σ(-)-X(3)Σ(-) and spin-forbidden transition b(1)Σ(+)(0(+))-X(3)(1)Σ(-)(0(+)) are found to be the strongest in their respective categories. Electric dipole moments of all the bound Λ-S states along with those of the two Ω-components of X(3)Σ(-) are also calculated in the present study.

  20. Transition from Sign-Reversed to Sign-Preserved Cooper-Pairing Symmetry in Sulfur-Doped Iron Selenide Superconductors.

    PubMed

    Wang, Qisi; Park, J T; Feng, Yu; Shen, Yao; Hao, Yiqing; Pan, Bingying; Lynn, J W; Ivanov, A; Chi, Songxue; Matsuda, M; Cao, Huibo; Birgeneau, R J; Efremov, D V; Zhao, Jun

    2016-05-13

    An essential step toward elucidating the mechanism of superconductivity is to determine the sign or phase of the superconducting order parameter, as it is closely related to the pairing interaction. In conventional superconductors, the electron-phonon interaction induces attraction between electrons near the Fermi energy and results in a sign-preserved s-wave pairing. For high-temperature superconductors, including cuprates and iron-based superconductors, prevalent weak coupling theories suggest that the electron pairing is mediated by spin fluctuations which lead to repulsive interactions, and therefore that a sign-reversed pairing with an s_{±} or d-wave symmetry is favored. Here, by using magnetic neutron scattering, a phase sensitive probe of the superconducting gap, we report the observation of a transition from the sign-reversed to sign-preserved Cooper-pairing symmetry with insignificant changes in T_{c} in the S-doped iron selenide superconductors K_{x}Fe_{2-y}(Se_{1-z}S_{z})_{2}. We show that a rather sharp magnetic resonant mode well below the superconducting gap (2Δ) in the undoped sample (z=0) is replaced by a broad hump structure above 2Δ under 50% S doping. These results cannot be readily explained by simple spin fluctuation-exchange pairing theories and, therefore, multiple pairing channels are required to describe superconductivity in this system. Our findings may also yield a simple explanation for the sometimes contradictory data on the sign of the superconducting order parameter in iron-based materials.

  1. Physical and biophysical assessment of highly fluorescent, magnetic quantum dots of a wurtzite-phase manganese selenide system.

    PubMed

    Sarma, Runjun; Das, Queen; Hussain, Anowar; Ramteke, Anand; Choudhury, Amarjyoti; Mohanta, Dambarudhar

    2014-07-11

    Combining fluorescence and magnetic features in a non-iron based, select type of quantum dots (QDs) can have immense value in cellular imaging, tagging and other nano-bio interface applications, including targeted drug delivery. Herein, we report on the colloidal synthesis and physical and biophysical assessment of wurtzite-type manganese selenide (MnSe) QDs in cell culture media. Aiming to provide a suitable colloidal system of biological relevance, different concentrations of reactants and ligands (e.g., thioglycolic acid, TGA) have been considered. The average size of the QDs is ∼7 nm, which exhibited a quantum yield of ∼75% as compared to rhodamine 6 G dye(®). As revealed from time-resolved photoluminescence (TR-PL) response, the near band edge emission followed a bi-exponential decay feature with characteristic times of ∼0.64 ns and 3.04 ns. At room temperature, the QDs were found to exhibit paramagnetic features with coercivity and remanence impelled by TGA concentrations. With BSA as a dispersing agent, the QDs showed an improved optical stability in Dulbecco's Modified Eagle Media(®) (DMEM) and Minimum Essential Media(®) (MEM), as compared to the Roswell Park Memorial Institute(®) (RPMI-1640) media. Finally, the cell viability of lymphocytes was found to be strongly influenced by the concentration of MnSe QDs, and had a safe limit upto 0.5 μM. With BSA inclusion in cell media, the cellular uptake of MnSe QDs was observed to be more prominent, as revealed from fluorescence imaging. The fabrication of water soluble, nontoxic MnSe QDs would open up an alternative strategy in nanobiotechnology, while preserving their luminescent and magnetic properties intact.

  2. Thermoelectric properties of bismuth-selenide films with controlled morphology and texture grown using pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Le, Phuoc Huu; Liao, Chien-Neng; Luo, Chih Wei; Lin, Jiunn-Yuan; Leu, Jihperng

    2013-11-01

    Polycrystalline, thermoelectric thin films of bismuth selenide (Bi2Se3) were grown on SiO2/Si (1 1 1) substrates, using pulsed laser deposition (PLD). Bi2Se3 films with highly c-axis-oriented and controlled textures were fabricated by maintaining the helium gas pressure (P) between 0.7 and 173 Pa and the substrate temperature (Ts) between 200 and 350 °C. The carrier concentration (n) of films decreased with increasing P, which was attributed to the increase of Se concentration from Se deficiency (P ≤ 6.7 Pa) to stoichiometry to slight Se enrichment (P ≥ 40 Pa). The Seebeck coefficient (S) was enhanced considerably because of the reduction in n, following the S ˜ n-2/3 relation approximately. The average grain size increased from approximately 100 to 500 nm when Ts was raised from 200 to 350 °C, resulting in enhanced carrier mobility (μ) and electrical conductivity (σ) and a reduced full width at half maximum of (0 0 6) peaks. The shape of grains transformed from rice-like at Ts of 200-250 °C to layered-hexagonal platelets (L-HPs) or super-layered flakes (S-LFs) at Ts of 300-350 °C. Films that were grown at 300 °C and 40 Pa and contained highly c-axis oriented L-HPs possessed the highest power factor (PF = S2σ), which reached 5.54 μW cm-1 K-2, where S = 75.8 μV/K and σ = 963.8 S cm-1.

  3. Process Of Bonding Copper And Tungsten

    DOEpatents

    Slattery, Kevin T.; Driemeyer, Daniel E.; Davis, John W.

    2000-07-18

    Process for bonding a copper substrate to a tungsten substrate by providing a thin metallic adhesion promoting film bonded to a tungsten substrate and a functionally graded material (FGM) interlayer bonding the thin metallic adhesion promoting film to the copper substrate. The FGM interlayer is formed by sintering a stack of individual copper and tungsten powder blend layers having progressively higher copper content/tungsten content, by volume, ratio values in successive powder blend layers in a lineal direction extending from the tungsten substrate towards the copper substrate. The resulting copper to tungsten joint well accommodates the difference in the coefficient of thermal expansion of the materials.

  4. Tin sulfide and selenide clusters soluble in organic solvents with the core structures of Sn4S6 and Sn4Se6.

    PubMed

    Zhong, Mingdong; Yang, Zhi; Yi, Yafei; Zhang, Dongxiang; Sun, Kening; Roesky, Herbert W; Yang, Ying

    2015-12-14

    Reactions of LSnCl (1) (L = N(2,6-iPr2C6H3)(SiMe3)) with sulfur and selenium, respectively under mild conditions yielded two tin chalcogenide clusters. Surprisingly the tin atoms of the L4Sn4S6 (2) and L4Sn4Se6 (3) clusters are oxidized from Sn(II) of the precursor to Sn(IV) of the products under concomitant reduction of elemental sulfur and selenium to sulfide and selenide, respectively. The released chlorine radicals from the precursor LSnCl (1) react under oxidative addition with another LSnCl molecule to yield the side product LSnCl3 (4). The soluble nature of clusters 2 and 3 in organic solvents is a unique property of this class of compounds and makes them suitable for reactions in organic solvents. Compounds 2 and 3 were characterized by single crystal X-ray diffraction and multinuclear NMR investigations. Furthermore in ROP polymerization, the two products show high catalytic activity. For the first time a tin selenide compound functions in ROP catalysis.

  5. Factors controlling material deposition in the CVD of nickel sulfides, selenides or phosphides from dichalcogenoimidodiphosphinato complexes: deposition, spectroscopic and computational studies.

    PubMed

    Panneerselvam, Arunkumar; Periyasamy, Ganga; Ramasamy, Karthik; Afzaal, Mohammad; Malik, Mohammad A; O'Brien, Paul; Burton, Neil A; Waters, John; van Dongen, Bart E

    2010-07-14

    The series of nickel dichalcogenoimidodiphosphinates [Ni{(i)Pr(2)P(X1)NP(X2)(i)Pr(2)}(2)]: X1 = S, X2 = Se (1), X1 = X2 = S (2), and X1 = X2 = Se (3) have been successfully used as single-source precursors (SSPs) to deposit thin films of nickel sulfide, selenide or phosphide; the material deposited depended on both temperature and method used for the deposition. Aerosol-assisted (AA) chemical vapour deposition (CVD) and low-pressure (LP) CVD were used. The as-deposited films were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). A variety of phases including: Ni(2)P, Ni(0.85)Se and NiS(1.03) were deposited under different conditions. The mechanism of decomposition to the phosphide, selenide, or sulfide was studied by pyrolysis gas chromatography mass spectrometry (Py-GC-MS) and modelled by density functional theory (DFT).

  6. Biliary copper excretion by hepatocyte lysosomes in the rat. Major excretory pathway in experimental copper overload

    SciTech Connect

    Gross, J.B. Jr.; Myers, B.M.; Kost, L.J.; Kuntz, S.M.; LaRusso, N.F.

    1989-01-01

    We investigated the hypothesis that lysosomes are the main source of biliary copper in conditions of hepatic copper overload. We used a rat model of oral copper loading and studied the relationship between the biliary output of copper and lysosomal hydrolases. Male Sprague-Dawley rats were given tap water with or without 0.125% copper acetate for up to 36 wk. Copper loading produced a 23-fold increase in the hepatic copper concentration and a 30-65% increase in hepatic lysosomal enzyme activity. Acid phosphatase histochemistry showed that copper-loaded livers contained an increased number of hepatocyte lysosomes; increased copper concentration of these organelles was confirmed directly by both x ray microanalysis and tissue fractionation. The copper-loaded rats showed a 16-fold increase in biliary copper output and a 50-300% increase in biliary lysosomal enzyme output. In the basal state, excretory profiles over time were similar for biliary outputs of lysosomal enzymes and copper in the copper-loaded animals but not in controls. After pharmacologic stimulation of lysosomal exocytosis, biliary outputs of copper and lysosomal hydrolases in the copper-loaded animals remained coupled: injection of colchicine or vinblastine produced an acute rise in the biliary output of both lysosomal enzymes and copper to 150-250% of baseline rates. After these same drugs, control animals showed only the expected increase in lysosomal enzyme output without a corresponding increase in copper output. We conclude that the hepatocyte responds to an increased copper load by sequestering excess copper in an increased number of lysosomes that then empty their contents directly into bile. The results provide direct evidence that exocytosis of lysosomal contents into biliary canaliculi is the major mechanism for biliary copper excretion in hepatic copper overload.

  7. 21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). 73.2125 Section 73.2125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT... § 73.2125 Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). (a) Identity...

  8. 21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). 73.2125 Section 73.2125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT... § 73.2125 Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). (a) Identity...

  9. 21 CFR 73.1125 - Potassium sodium copper chloropyhllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). 73.1125 Section 73.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT....1125 Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). (a) Identity. (1) The...

  10. 21 CFR 73.1125 - Potassium sodium copper chloropyhllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). 73.1125 Section 73.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT....1125 Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). (a) Identity. (1) The...

  11. 21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). 73.2125 Section 73.2125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT... § 73.2125 Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). (a) Identity...

  12. 21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). 73.2125 Section 73.2125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT... § 73.2125 Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). (a) Identity...

  13. 21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). 73.2125 Section 73.2125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT... § 73.2125 Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). (a) Identity...

  14. 21 CFR 73.1125 - Potassium sodium copper chloropyhllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). 73.1125 Section 73.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT....1125 Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). (a) Identity. (1) The...

  15. Leaching of Copper Ore by Thiobacillus Ferrooxidans.

    ERIC Educational Resources Information Center

    Lennox, John; Biaha, Thomas

    1991-01-01

    A quantitative laboratory exercise based upon the procedures copper manufacturers employ to increase copper production is described. The role of chemoautotrophic microorganisms in biogeologic process is emphasized. Safety considerations when working with bacteria are included. (KR)

  16. Thermotransport in liquid aluminum-copper alloys

    NASA Technical Reports Server (NTRS)

    Bhat, B. N.

    1973-01-01

    A thermotransport study was made on a series of liquid aluminum-copper alloys which contained from trace amounts to 33 weight percent copper. The samples in the form of narrow capillaries were held in known temperature gradient of thermotransport apparatus until the stationary state was reached. The samples were analyzed for the concentration of copper along the length. Copper was observed to migrate to the colder regions in all the samples. The heat of transport, Q*, was determined for each composition from a plot of concentration of copper versus reciprocal absolute temperature. The value of Q* is the highest at trace amounts of copper (4850 cal/gm-atom), but decreases with increasing concentration of copper and levels off to 2550 cal/gm-atom at about 25 weight percent copper. The results are explained on the basis of electron-solute interaction and a gas model of diffusion.

  17. Molecular Mediators Governing Iron-Copper Interactions

    PubMed Central

    Gulec, Sukru; Collins, James F.

    2015-01-01

    Given their similar physiochemical properties, it is a logical postulate that iron and copper metabolism are intertwined. Indeed, iron-copper interactions were first documented over a century ago, but the homeostatic effects of one on the other has not been elucidated at a molecular level to date. Recent experimental work has, however, begun to provide mechanistic insight into how copper influences iron metabolism. During iron deficiency, elevated copper levels are observed in the intestinal mucosa, liver, and blood. Copper accumulation and/or redistribution within enterocytes may influence iron transport, and high hepatic copper may enhance biosynthesis of a circulating ferroxidase, which potentiates iron release from stores. Moreover, emerging evidence has documented direct effects of copper on the expression and activity of the iron-regulatory hormone hepcidin. This review summarizes current experimental work in this field, with a focus on molecular aspects of iron-copper interplay and how these interactions relate to various disease states. PMID:24995690

  18. Copper tolerance and virulence in bacteria

    PubMed Central

    Ladomersky, Erik; Petris, Michael J.

    2015-01-01

    Copper (Cu) is an essential trace element for all aerobic organisms. It functions as a cofactor in enzymes that catalyze a wide variety of redox reactions due to its ability to cycle between two oxidation states, Cu(I) and Cu(II). This same redox property of copper has the potential to cause toxicity if copper homeostasis is not maintained. Studies suggest that the toxic properties of copper are harnessed by the innate immune system of the host to kill bacteria. To counter such defenses, bacteria rely on copper tolerance genes for virulence within the host. These discoveries suggest bacterial copper intoxication is a component of host nutritional immunity, thus expanding our knowledge of the roles of copper in biology. This review summarizes our current understanding of copper tolerance in bacteria, and the extent to which these pathways contribute to bacterial virulence within the host. PMID:25652326

  19. Placental copper transport in the brindled mouse

    SciTech Connect

    Garnica, A.; Bates, J.

    1986-03-01

    Pregnant brindled (brin) mice were injected at 16 or 19 days gestation with 2 doses of CuCl/sub 2/ 6 mcg/g/dose, separated by 12 h, and sacrificed 6 h after the second. The copper conc. in placenta (P) and kidneys (K) of uninjected (UI) brin mice were higher than in UI controls, while conc. in liver (L) and fetal carcass (F) were lower. After injection (I), placental copper conc. increased while the carcass conc. remained unchanged. Brin mouse is a model for the human inborn error of copper metabolism, Menkes syndrome, which is characterized by signs of copper deficiency. These data indicate that metabolism of copper in brin fetus is abnormal, but depressed fetal copper levels cannot be corrected by acute copper dosing because of the sequestration of copper in placenta.

  20. Copper tolerance and virulence in bacteria.

    PubMed

    Ladomersky, Erik; Petris, Michael J

    2015-06-01

    Copper (Cu) is an essential trace element for all aerobic organisms. It functions as a cofactor in enzymes that catalyze a wide variety of redox reactions due to its ability to cycle between two oxidation states, Cu(I) and Cu(II). This same redox property of copper has the potential to cause toxicity if copper homeostasis is not maintained. Studies suggest that the toxic properties of copper are harnessed by the innate immune system of the host to kill bacteria. To counter such defenses, bacteria rely on copper tolerance genes for virulence within the host. These discoveries suggest bacterial copper intoxication is a component of host nutritional immunity, thus expanding our knowledge of the roles of copper in biology. This review summarizes our current understanding of copper tolerance in bacteria, and the extent to which these pathways contribute to bacterial virulence within the host.

  1. Application of saccharose as copper(II) ligand for electroless copper plating solutions.

    PubMed

    Norkus, Eugenijus; Prusinskas, Kestutis; Vaskelis, Algirdas; Jaciauskiene, Jane; Stalnioniene, Irena; Macalady, Donald L

    2007-01-15

    Saccharose, forming sufficiently stable complexes with copper(II) ions in alkaline solutions, was found to be a suitable ligand for copper(II) chelating in alkaline (pH>12) electroless copper deposition solutions. Reduction of copper(II)-saccharose complexes by hydrated formaldehyde was investigated and the copper deposits formed were characterized. The thickness of the compact copper coatings obtained under optimal operating conditions in 1h reaches ca. 2 microm at ambient temperature. The plating solutions were stable and no signs of Cu(II) reduction in the bulk solution were observed. Results were compared with those systems operating with other copper(II) ligands.

  2. Textured carbon surfaces on copper by sputtering

    NASA Technical Reports Server (NTRS)

    Curren, A. N. (Inventor); Jensen, K. A. (Inventor); Roman, R. F. (Inventor)

    1986-01-01

    A very thin layer of highly textured carbon is applied to a copper surface by a triode sputtering process. A carbon target and a copper substrate are simultaneously exposed to an argon plasma in a vacuum chamber. The resulting carbon surface is characterized by a dense, random array of needle like spires or peaks which extend perpendicularly from the copper surface. The coated copper is especially useful for electrode plates in multistage depressed collectors.

  3. 21 CFR 184.1261 - Copper sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Copper sulfate. 184.1261 Section 184.1261 Food and... Substances Affirmed as GRAS § 184.1261 Copper sulfate. (a) Copper sulfate (cupric sulfate, CuSO4·5H2O, CAS... the reaction of sulfuric acid with cupric oxide or with copper metal. (b) The ingredient must be of...

  4. 21 CFR 184.1261 - Copper sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Copper sulfate. 184.1261 Section 184.1261 Food and... Substances Affirmed as GRAS § 184.1261 Copper sulfate. (a) Copper sulfate (cupric sulfate, CuSO4·5 H2O, CAS... the reaction of sulfuric acid with cupric oxide or with copper metal. (b) The ingredient must be of...

  5. 21 CFR 184.1261 - Copper sulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Copper sulfate. 184.1261 Section 184.1261 Food and....1261 Copper sulfate. (a) Copper sulfate (cupric sulfate, CuSO4·5 H2O, CAS Reg. No. 7758-99-8) usually... sulfuric acid with cupric oxide or with copper metal. (b) The ingredient must be of a purity suitable...

  6. 21 CFR 184.1261 - Copper sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Copper sulfate. 184.1261 Section 184.1261 Food and... Substances Affirmed as GRAS § 184.1261 Copper sulfate. (a) Copper sulfate (cupric sulfate, CuSO4·5H2O, CAS... the reaction of sulfuric acid with cupric oxide or with copper metal. (b) The ingredient must be of...

  7. 21 CFR 184.1261 - Copper sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Copper sulfate. 184.1261 Section 184.1261 Food and... Substances Affirmed as GRAS § 184.1261 Copper sulfate. (a) Copper sulfate (cupric sulfate, CuSO4·5 H2O, CAS... the reaction of sulfuric acid with cupric oxide or with copper metal. (b) The ingredient must be of...

  8. Copper Post-CMP Cleaning

    NASA Astrophysics Data System (ADS)

    Starosvetsky, D.; Ein-Eli, Y.

    Copper on-chip interconnects Damascene technology utilizes chemical mechanical polishing (CMP) in order to remove copper overburden after its electro deposition and achieve global planarization of patterned surface. CMP is a simultaneous action of mechanical overburden metal removal and its electrochemical dissolution. It is performed with the movement of a polisher pad in acidic or alkaline aqueous CMP electrolytes (slurry) containing dispersive abrasive particles (Al2O3 or SiO2), pH buffer, certain electrolyte salts to control ionic strength, oxidants, and corrosion inhibitors. Mechanical and chemical interactions with a patterned wafer surface introduce different defects and contaminations in interlayer dielectric (ILD) surfaces and copper layers. These can either be mechanical (physical) or chemical-based defects and contaminants [1-6].

  9. The copper microRNAs.

    PubMed

    Pilon, Marinus

    2017-02-01

    1030 I. 1030 II. 1030 III. 1031 IV. 1031 V. 1032 VI. 1033 VII. 1034 VIII. 1034 1034 References 1034 SUMMARY: Copper (Cu) microRNAs are upregulated by Cu deficiency and mediate the post-transcriptional downregulation of transcripts that encode Cu proteins, suggesting a role directly related to Cu. However, expression and phenotypic analyses of copper microRNA mutants and over-expressors have suggested roles mainly in tolerance to abiotic stresses. To reconcile available data, a model is proposed which emphasizes the mobile nature of copper microRNA molecules in the regulation of Cu homeostasis. It is proposed that the Cu-microRNA regulatory circuits are further co-opted by plants to regulate both beneficial and pathogenic interactions with microbes. Further exploration of Cu-microRNA functions that account for the cell-to-cell mobility should give novel insight into plant microbe interactions and the integration of micronutrition and development.

  10. Contribution of Copper Ion Resistance to Survival of Escherichia coli on Metallic Copper Surfaces▿

    PubMed Central

    Santo, Christophe Espírito; Taudte, Nadine; Nies, Dietrich H.; Grass, Gregor

    2008-01-01

    Bacterial contamination of touch surfaces poses a serious threat for public health. The use of bactericidal surface materials, such as copper and its alloys, might constitute a way to aid the use of antibiotics and disinfectants, thus minimizing the risk of emergence and spread of multiresistant germs. The survival of Escherichia coli on metallic copper surfaces has been studied previously; however, the mechanisms underlying bacterial inactivation on copper surfaces have not been elucidated. Data presented in this study suggest that bacteria are killed rapidly on dry copper surfaces. Several factors, such as copper ion toxicity, copper chelators, cold, osmotic stress, and reactive oxygen species, but not anaerobiosis, influenced killing rates. Strains deleted in copper detoxification systems were slightly more sensitive than was the wild type. Preadaptation to copper enhanced survival rates upon copper surface exposure. This study constitutes a first step toward understanding the reasons for metallic copper surface-mediated killing of bacteria. PMID:18156321

  11. THE EVOLUTION OF SYNTHETICALLY PRECIPITATED COPPER SOLIDS

    EPA Science Inventory

    The objective of this study was to explore the effect of water quality, particularly chloride and sulfate, on copper mineral formation. Copper-sulfate and chloride compounds are often found on the surface of copper pipes in drinking water distribution systems. When attempting to ...

  12. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Copper powder. 73.2647 Section 73.2647 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity and specifications to the requirements of §...

  13. 21 CFR 524.463 - Copper naphthenate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Copper naphthenate. 524.463 Section 524.463 Food... DRUGS, FEEDS, AND RELATED PRODUCTS OPHTHALMIC AND TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.463 Copper naphthenate. (a) Amount. The drug is a 37.5 percent solution of copper naphthenate. (b) Sponsors. See...

  14. 21 CFR 524.463 - Copper naphthenate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Copper naphthenate. 524.463 Section 524.463 Food... DRUGS, FEEDS, AND RELATED PRODUCTS OPHTHALMIC AND TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.463 Copper naphthenate. (a) Amount. The drug is a 37.5 percent solution of copper naphthenate. (b) Sponsors. See...

  15. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Copper powder. 73.2647 Section 73.2647 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity and specifications to the requirements of §...

  16. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Copper powder. 73.2647 Section 73.2647 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity and specifications to the requirements of §...

  17. Copper toxicity in aquaculture: A practical approach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Copper sulfate is used as a therapeutant for various applications in aquaculture. There is a great deal of information on the toxicity of copper, especially in low-alkalinity waters; however, much of this information is fragmented, and a comprehensive guide of copper toxicity and safe concentration...

  18. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Copper powder. 73.2647 Section 73.2647 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity and specifications to the requirements of §...

  19. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Copper powder. 73.2647 Section 73.2647 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity and specifications to the requirements of §...

  20. 21 CFR 524.463 - Copper naphthenate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Copper naphthenate. 524.463 Section 524.463 Food... DRUGS, FEEDS, AND RELATED PRODUCTS OPHTHALMIC AND TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.463 Copper naphthenate. (a) Amount. The drug is a 37.5 percent solution of copper naphthenate. (b) Sponsors. See...

  1. 21 CFR 524.463 - Copper naphthenate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Copper naphthenate. 524.463 Section 524.463 Food... DRUGS, FEEDS, AND RELATED PRODUCTS OPHTHALMIC AND TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.463 Copper naphthenate. (a) Amount. The drug is a 37.5 percent solution of copper naphthenate. (b) Sponsors. See...

  2. Measuring bioavailable copper using anodic stripping voltammetry

    SciTech Connect

    Deaver, E.; Rodgers, J.H. Jr.

    1996-11-01

    Since speciation can affect bioavailability and toxicity of copper in aquatic systems, accurate predictions of effects of bioavailable forms require detection and/or measurement of these forms. To develop an approach for measurement of bioavailable copper, a copper sulfate solution was used in 10-d aqueous and sediment toxicity tests with Hyalella azteca Saussure. These tests encompassed ranges of pH, alkalinity, hardness, and conductivity. Changes in copper speciation were measured using atomic absorption spectroscopy (AA) for dissolved copper and differential pulse anodic stripping voltammetry (DPASV) for labile copper, and concentrations were evaluated relative to amphipod survival. Ten-day LC50s based on AA-measured aqueous copper concentrations ranged from 42 to 142 {micro}g Cu/L, and LC50s based on DPASV-measured copper concentrations ranged from 17.4 to 24.8 {micro}g Cu/L. In 10-d tests using copper-amended sediments with diverse characteristics and AA-measured copper concentrations spanning an order of magnitude, total copper concentrations were not predictive of sediment toxicity, but H. azteca survival was explained by DPASV measurements that varied by {le}4%. In order to make defensible estimates of the potential risk of metals in sediments or water, it is essential to identify the fraction of total metal that is bioavailable. In these experiments, DPASV was useful for measuring bioavailable copper in aqueous and sediment tests with H. azteca.

  3. Copper accumulation in the crayfish (Orconectes rusticus)

    SciTech Connect

    Evans, M.L.

    1980-06-01

    The purpose of this study was to determine whether or not the crayfish, O. rusticus could fulfill Nehring's (1976) criteria for a good biological monitor of heavy metal pollution. Since there is some evidence that the cupric ion is the most toxic form of aqueous copper, crayfish-accumulated copper was compared to both total and cupric copper in the culture water.

  4. Relationship between soil copper content and copper content of selected crop plants in central Chile.

    PubMed

    Badilla-Ohlbaum, R; Ginocchio, R; Rodríguez, P H; Céspedes, A; González, S; Allen, H E; Lagos, G E

    2001-12-01

    A survey of copper levels in agricultural soils of central Chile revealed two soil clusters-one with a mean copper level of 162 mg/kg and one with a mean copper level of 751 mg/kg of soil. Samples of soils from both soil clusters were characterized on the basis of physicochemical characteristics, and copper extractability was compared by saturation and CaCl2 extraction as well as an acid-leaching procedure (TCLP). We also measured the copper content of various tissues of tomato (Lycopersicon esculentum) and onion (Allium cepa) crops growing on these soils. Other than copper levels, soils from the two clusters were quite similar, with slightly greater levels of molybdenum and cadmium in the high-copper soils. Within each cluster, extracted copper levels and total soil copper levels were not correlated. However, the three extraction procedures solubilized significantly more copper from the high-Cu soils. Mineralogical characterization of the soil particles and depth profiles of soil metal levels in a subsample of sites suggested that highly insoluble copper ore and mining wastes might account for the high copper levels. Neither total nor extractable copper levels allowed statistical prediction of the levels of copper in plant tissue. The edible tissues of both crops had the same mean copper content, regardless of the copper soil level. However, copper contents of stems and leaves were significantly higher for plants growing on the high-Cu soils. These results show that in these soils, high copper levels are associated with very insoluble copper species and thus low bioavailability of copper to crop plants.

  5. Molybdenum-copper and tungsten-copper alloys and method of making

    DOEpatents

    Schmidt, F.A.; Verhoeven, J.D.; Gibson, E.D.

    1989-05-23

    Molybdenum-copper and tungsten-copper alloys are prepared by a consumable electrode method in which the electrode consists of a copper matrix with embedded strips of refractory molybdenum or tungsten. The electrode is progressively melted at its lower end with a superatmospheric inert gas pressure maintained around the liquefying electrode. The inert gas pressure is sufficiently above the vapor pressure of copper at the liquidus temperature of the alloy being formed to suppress boiling of liquid copper. 6 figs.

  6. Molybdenum-copper and tungsten-copper alloys and method of making

    DOEpatents

    Schmidt, Frederick A.; Verhoeven, John D.; Gibson, Edwin D.

    1989-05-23

    Molybdenum-copper and tungsten-copper alloys are prepared by a consumable electrode method in which the electrode consists of a copper matrix with embedded strips of refractory molybdenum or tungsten. The electrode is progressively melted at its lower end with a superatmospheric inert gas pressure maintained around the liquifying electrode. The inert gas pressure is sufficiently above the vapor pressure of copper at the liquidus temperature of the alloy being formed to suppress boiling of liquid copper.

  7. Copper vs. Copper at the Relativistic Heavy Ion Collider (2005)

    SciTech Connect

    Brookhaven Lab - Fulvia Pilat

    2009-06-09

    To investigate a new form of matter not seen since the Big Bang, scientists are using a new experimental probe: collisions between two beams of copper ions. The use of intermediate size nuclei is expected to result in intermediate energy density - not as

  8. Copper vs. Copper at the Relativistic Heavy Ion Collider (2005)

    ScienceCinema

    Brookhaven Lab - Fulvia Pilat

    2016-07-12

    To investigate a new form of matter not seen since the Big Bang, scientists are using a new experimental probe: collisions between two beams of copper ions. The use of intermediate size nuclei is expected to result in intermediate energy density - not as

  9. Electrochemical nucleation and growth of copper and copper alloys

    NASA Astrophysics Data System (ADS)

    Shao, Wenbo

    This dissertation aims to contribute to a fundamental understanding of the physicochemical processes occurring in electrochemical nucleation and growth. To this end, the effects of various anions (chloride (Cl-), sulfate (SO42-) and sulfamate (NH2SO 3-)) on the electrochemical kinetics and the mechanism of copper reduction, as well as on the microstructure of the resulting films, were studied. On the basis of this work, the deposition of copper alloys (Cu-Ag with positive heat of mixing, Cu-Au with negative heat of mixing) was investigated with the main objective to achieve an insight on the role of solid state thermodynamics on the electrocrystallization process. Chloride ions cause two competing effects: at low chloride concentration the formation of an adsorbed chloride layer introduces an additional reaction pathway, resulting in an overall depolarization of the reduction process with no significant change of the Tafel slope. At high chloride concentration, complexation phenomena induce a cathodic polarization of the deposition process and a decrease in the Tafel slope. Chlorides cause a decrease in the density and an increased size of copper nuclei. Sulfamate depolarizes copper reduction the most and results in the largest nucleus density. Chloride promotes the faceting, and dendritic growth of copper deposits along <110> direction by introducing interfacial anisotropy. Addition of Ag in the solution or in the electrode substrate enhances copper deposition and results in an additional reduction peak. Codeposition of Cu-Ag increases nucleus density and decreases nucleus size. Such enhancement of copper deposition, the increase in nucleus density and the decrease in nucleus size by Ag could be due to the continued formation of a surface alloy of Cu-Ag and the fast interface dynamics of Ag deposition. Cu can be underpotentially codeposited in the Cu-Au alloy. Homogeneous solid solutions are grown under conditions of underpotential deposition of Cu, while

  10. A novel technique for nano-scale lithography of cadmium selenide via a scanning tunneling microscope tip-induced reaction

    NASA Astrophysics Data System (ADS)

    Olson, Joel Andrew

    In the introductory chapter the physical and interfacial properties of cadmium selenide are presented, as well as a discussion of select surface properties of CdSe. Also, a brief review of scanning probe lithographic techniques currently under investigation is presented. As a portion of the project presented herein, a research-grade scanning tunneling microscope was constructed. The second chapter includes information specific to this instrument. Included are descriptions of the electrical components, descriptions of the mechanical components, and a description of the noise reduction and calibration of the instrument. When cleaved-in-air (112¯0) CdSe is imaged repeatedly under humidified conditions, small (˜20 nm wide and between 6 A and 12 A in height) features are observed to form. The features are similar in shape to one another, suggesting tip imaging. Under an atmosphere of dried nitrogen feature growth is not observed. The growth of the features shows a strong dependence on both the tunneling current and the bias voltage. The initial rate of feature growth increases with tunneling current. Feature growth as a function of bias voltage displays an onset at a sample bias of -1. 2 V to -1. 3 V and is no longer observed at sample biases more negative than -2.5 V. Two possible models are presented for feature growth. The smallest feature observed is ˜6 nm in width. The fourth chapter describes simple and inexpensive classroom demonstrations of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI). The demonstrations comprise common orienteering compasses, whose needles represent magnetic dipoles, along with three collinear permanent magnets, and a magnetic stir plate or pulseable electromagnets. The trio of permanent magnets provides a laterally uniform magnetic field, whose strength decreases with distance from the magnets. Resonance can be observed by adjusting the frequency of the magnetic stirrer when it is in close proximity to the compasses

  11. Advantages and challenges of increased antimicrobial copper use and copper mining.

    PubMed

    Elguindi, Jutta; Hao, Xiuli; Lin, Yanbing; Alwathnani, Hend A; Wei, Gehong; Rensing, Christopher

    2011-07-01

    Copper is a highly utilized metal for electrical, automotive, household objects, and more recently as an effective antimicrobial surface. Copper-containing solutions applied to fruits and vegetables can prevent bacterial and fungal infections. Bacteria, such as Salmonellae and Cronobacter sakazakii, often found in food contamination, are rapidly killed on contact with copper alloys. The antimicrobial effectiveness of copper alloys in the healthcare environment against bacteria causing hospital-acquired infections such as methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli O157:H7, and Clostridium difficile has been described recently. The use of copper and copper-containing materials will continue to expand and may lead to an increase in copper mining and production. However, the copper mining and manufacturing industry and the consumer do not necessarily enjoy a favorable relationship. Open pit mining, copper mine tailings, leaching products, and deposits of toxic metals in the environment often raises concerns and sometimes public outrage. In addition, consumers may fear that copper alloys utilized as antimicrobial surfaces in food production will lead to copper toxicity in humans. Therefore, there is a need to mitigate some of the negative effects of increased copper use and copper mining. More thermo-tolerant, copper ion-resistant microorganisms could improve copper leaching and lessen copper groundwater contamination. Copper ion-resistant bacteria associated with plants might be useful in biostabilization and phytoremediation of copper-contaminated environments. In this review, recent progress in microbiological and biotechnological aspects of microorganisms in contact with copper will be presented and discussed, exploring their role in the improvement for the industries involved as well as providing better environmental outcomes.

  12. Metabolic crossroads of iron and copper

    PubMed Central

    Collins, James F; Prohaska, Joseph R; Knutson, Mitchell D

    2013-01-01

    Interactions between the essential dietary metals, iron and copper, have been known for many years. This review highlights recent advances in iron-copper interactions with a focus on tissues and cell types important for regulating whole-body iron and copper homeostasis. Cells that mediate dietary assimilation (enterocytes) and storage and distribution (hepatocytes) of iron and copper are considered, along with the principal users (erythroid cells) and recyclers of red cell iron (reticuloendothelial macrophages). Interactions between iron and copper in the brain are also discussed. Many unanswered questions regarding the role of these metals and their interactions in health and disease emerge from this synopsis, highlighting extensive future research opportunities. PMID:20384844

  13. Building a Copper Pipe "Xylophone."

    ERIC Educational Resources Information Center

    Lapp, David R.

    2003-01-01

    Explains how to use the equation for frequency of vibration of a transversely oscillating bar or pipe with both ends free to vibrate to build a simple and inexpensive xylophone from a 3-meter section of copper pipe. The instrument produces a full major scale and can be used to investigate various musical intervals. (Author/NB)

  14. PLUTONIUM-CERIUM-COPPER ALLOYS

    DOEpatents

    Coffinberry, A.S.

    1959-05-12

    A low melting point plutonium alloy useful as fuel is a homogeneous liquid metal fueled nuclear reactor is described. Vessels of tungsten or tantalum are useful to contain the alloy which consists essentially of from 10 to 30 atomic per cent copper and the balance plutonium and cerium. with the plutontum not in excess of 50 atomic per cent.

  15. COPPER CORROSION AND SOLUBILITY RESEARCH

    EPA Science Inventory

    This poster provides a very cursory summary of TTEB in-house copper research experimental systems, and extramural research projects. The field studies summarized are the Indian Hill (OH) study of the use of orthophosphate for reducing cuprosolvency in a high alkalinity water, an...

  16. Tetraphenylphosphonium copper(I) dicyanamide.

    SciTech Connect

    Schlueter, J. A.; Geiser, U.; Materials Science Division

    2007-01-01

    In the title compound, {l_brace}(C{sub 24}H{sub 20}P)[Cu(C{sub 2}N{sub 3}){sub 2}]{r_brace}{sub n}, the copper(I) dicyanamide anion forms a distorted three-dimensional single diamondoid network. Templating tetraphenylphosphonium cations reside within the cavities of the polymeric anion.

  17. Crystallization of copper metaphosphate glass

    NASA Technical Reports Server (NTRS)

    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.

  18. Copper sulfate: Liquid or crystals?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two separate experiments were conducted to evaluate copper toxicity to channel catfish and free-swimming Ichthyophthirius multifiliis or Ich (the stage of Ich that can be treated); the compounds we used were CuSO4 crystals and a non-chelated liquid CuSO4 product. In 96 hr tests conducted in aquaria...

  19. CopperCore Service Integration

    ERIC Educational Resources Information Center

    Vogten, Hubert; Martens, Harrie; Nadolski, Rob; Tattersall, Colin; van Rosmalen, Peter; Koper, Rob

    2007-01-01

    In an e-learning environment there is a need to integrate various e-learning services like assessment services, collaboration services, learning design services and communication services. In this article we present the design and implementation of a generic integrative service framework, called CopperCore Service Integration (CCSI). We will…

  20. Reactivity test between beryllium and copper

    SciTech Connect

    Kawamura, H.; Kato, M.

    1995-09-01

    Beryllium has been expected for using as plasma facing material on ITER. And, copper alloy has been proposed as heat sink material behind plasma facing components. Therefore, both materials must be joined. However, the elementary process of reaction between beryllium and copper alloy does not clear in detail. For example, other authors reported that beryllium reacted with copper at high temperature, but it was not obvious about the generation of reaction products and increasing of the reaction layer. In the present work, from this point, for clarifying the elementary process of reaction between beryllium and copper, the out-of-pile compatibility tests were conducted with diffusion couples of beryllium and copper which were inserted in the capsule filled with high purity helium gas (6N). Annealing temperatures were 300, 400, 500, 600 and 700{degrees}C, and annealing periods were 100, 300 and 1000h. Beryllium specimens were hot pressed beryllium, and copper specimens were OFC (Oxygen Free Copper).