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Sample records for mn se mo

  1. The effect of Mn substitution on the structure and magnetic properties of Se(Cu1-xMnx)O3 solid solution

    International Nuclear Information System (INIS)

    Escamilla, R; Duran, A; Rosales, M I; Moran, E; Alario-Franco, M A

    2003-01-01

    The effects of Mn substitution on the structure and magnetic properties of the SeMO 3 (M = Cu 1-x Mn x ) solid solution have been studied. Rietveld refinements of the x-ray diffraction patterns of these samples indicate that the manganese ions occupy copper sites. This replacement induces significant changes in the M-O bond lengths that give rise to abrupt decreases of the [M-O 6 ] octahedral distortion. In contrast, the M-O(1)-M and M-O(2)-M bond angles remain essentially constant. The magnetic behaviour of this solid solution was studied in the temperature range of 2 K 3 . At about 10% of Mn there is a change from positive to negative Weiss constant θ W that is mainly due to the [M-O 6 ] octahedral distortion introduced by the substitution of the larger Mn ions in the structure. The M- H isotherms show a weak ferromagnetism at about 52 K in SeMnO 3

  2. The effect of Mn substitution on the structure and magnetic properties of Se(Cu sub 1 sub - sub x Mn sub x)O sub 3 solid solution

    CERN Document Server

    Escamilla, R; Rosales, M I; Moran, E C; Alario-Franco, M A

    2003-01-01

    The effects of Mn substitution on the structure and magnetic properties of the SeMO sub 3 (M = Cu sub 1 sub - sub x Mn sub x) solid solution have been studied. Rietveld refinements of the x-ray diffraction patterns of these samples indicate that the manganese ions occupy copper sites. This replacement induces significant changes in the M-O bond lengths that give rise to abrupt decreases of the [M-O sub 6] octahedral distortion. In contrast, the M-O(1)-M and M-O(2)-M bond angles remain essentially constant. The magnetic behaviour of this solid solution was studied in the temperature range of 2 K < T < 300 K. The temperature dependence of the inverse magnetic susceptibility is well described by the Curie-Weiss law at high temperatures, in the composition range studied. We found that the substitution of Mn for Cu induces a sharp drop in the saturation moment of SeCuO sub 3. At about 10% of Mn there is a change from positive to negative Weiss constant theta sub W that is mainly due to the [M-O sub 6] octahe...

  3. Achieving tunable doping of MoSe2 based devices using GO@MoSe2 heterostructure

    Science.gov (United States)

    Maji, Tuhin Kumar; Tiwary, Krishna Kanhaiya; Karmakar, Debjani

    2017-05-01

    Doping nature of MoSe2, one of the promising Graphene analogous device material, can be tuned by controlling the concentration of functional groups in Graphene oxide (GO)@MoSe2 heterostructure. In this study, by first-principles simulation, we have observed that GO can be used as a carrier injection layer for MoSe2, where n or p type carriers are introduced within MoSe2 layer depending on the type and concentration of functional moieties in it. Both n and p-type Schottky barrier height modulations are investigated for different modeled configurations of the heterostructure. This combinatorial heterostructure can be a promising material for future electronic device application.

  4. MnMoO4 nanolayers : Synthesis characterizations and electrochemical detection of QA

    Science.gov (United States)

    Muthamizh, S.; Kumar, S. Praveen; Munusamy, S.; Narayanan, V.

    2018-04-01

    MnMoO4 nanolayers were prepared by precipitation method. The MnMoO4 nanolayers were synthesized by using commercially available (CH3COO)2Mn.4H2O and Na2WO4.2H2O. The XRD pattern reveals that the synthesized MnMoO4 has monoclinic structure. In addition, lattice parameter values were also calculated using XRD data. The Raman analysis confirm the presence of Mo-O in MnMoO4 nanolayers. DRS-UV analysis shows that MnMoO4 has a band gap of 2.59 eV. FE-SEM and HR-TEM analysis along with EDAX confirms the material morphology in stacked layers like structure in nano scale. Synthesized nanolayers were utilized for the detection of biomolecule quercetin (QA).

  5. Removal of As, Mn, Mo, Se, U, V and Zn from groundwater by zero-valent iron in a passive treatment cell: reaction progress modeling

    Science.gov (United States)

    Morrison, Stan J.; Metzler, Donald R.; Dwyer, Brian P.

    2002-05-01

    Three treatment cells were operated at a site near Durango, CO. One treatment cell operated for more than 3 years. The treatment cells were used for passive removal of contamination from groundwater at a uranium mill tailings repository site. Zero-valent iron [Fe(0)] that had been powdered, bound with aluminosilicate and molded into plates was used as a reactive material in one treatment cell. The others used granular Fe(0) and steel wool. The treatment cells significantly reduced concentrations of As, Mn, Mo, Se, U, V and Zn in groundwater that flowed through it. Zero-valent iron [Fe(0)], magnetite (Fe 3O 4), calcite (CaCO 3), goethite (FeOOH) and mixtures of contaminant-bearing phases were identified in the solid fraction of one treatment cell. A reaction progress approach was used to model chemical evolution of water chemistry as it reacted with the Fe(0). Precipitation of calcite, ferrous hydroxide [Fe(OH) 2] and ferrous sulfide (FeS) were used to simulate observed changes in major-ion aqueous chemistry. The amount of reaction progress differed for each treatment cell. Changes in contaminant concentrations were consistent with precipitation of reduced oxides (UO 2, V 2O 3), sulfides (As 2S 3, ZnS), iron minerals (FeSe 2, FeMoO 4) and carbonate (MnCO 3). Formation of a free gas phase and precipitation of minerals contributed to loss of hydraulic conductivity in one treatment cell.

  6. Luminescence of nanocrystalline ZnSe:Mn2+

    NARCIS (Netherlands)

    Suyver, J.F.; Wuister, S.F.; Kelly, J.J.; Meijerink, A.

    2000-01-01

    The luminescence properties of nanocrystalline ZnSe:Mn^(2+) prepared via an inorganic chemical synthesis are described. Photoluminescence spectra show distinct ZnSe and Mn^(2+) related emissions, both of which are excited via the ZnSe host lattice. The Mn^(2+) emission wavelength and the

  7. Synthesis and nonlinear optical property of polycrystalline MnTeMoO_6

    International Nuclear Information System (INIS)

    Jin, Chengguo

    2017-01-01

    Polycrystalline MnTeMoO_6 powder has been synthesized by a new approach that MnO_2 is used as the manganese source. The transformation mechanism of manganese ions in the new approach has been discussed. The nonlinear optical property of polycrystalline MnTeMoO_6 has been investigated, and compared with single-crystalline samples. The transformation Mn"4"+ → Mn"2"+ may be formed directly without stable intermediates, and TeO_2 may serve as catalyst. The SHG response of polycrystalline MnTeMoO_6 powder is worse than that of single-crystalline powder in the same particle size distribution as its pseudo-size. The results indicate that it should pay special attention with the pseudo-size of polycrystalline powder when the potential nonlinear optical materials are screened by powder second harmonic generation measurements. (orig.)

  8. Interstitial Mo-Assisted Photovoltaic Effect in Multilayer MoSe2 Phototransistors.

    Science.gov (United States)

    Kim, Sunkook; Maassen, Jesse; Lee, Jiyoul; Kim, Seung Min; Han, Gyuchull; Kwon, Junyeon; Hong, Seongin; Park, Jozeph; Liu, Na; Park, Yun Chang; Omkaram, Inturu; Rhyee, Jong-Soo; Hong, Young Ki; Yoon, Youngki

    2018-03-01

    Thin-film transistors (TFTs) based on multilayer molybdenum diselenide (MoSe 2 ) synthesized by modified atmospheric pressure chemical vapor deposition (APCVD) exhibit outstanding photoresponsivity (103.1 A W -1 ), while it is generally believed that optical response of multilayer transition metal dichalcogenides (TMDs) is significantly limited due to their indirect bandgap and inefficient photoexcitation process. Here, the fundamental origin of such a high photoresponsivity in the synthesized multilayer MoSe 2 TFTs is sought. A unique structural characteristic of the APCVD-grown MoSe 2 is observed, in which interstitial Mo atoms exist between basal planes, unlike usual 2H phase TMDs. Density functional theory calculations and photoinduced transfer characteristics reveal that such interstitial Mo atoms form photoreactive electronic states in the bandgap. Models indicate that huge photoamplification is attributed to trapped holes in subgap states, resulting in a significant photovoltaic effect. In this study, the fundamental origin of high responsivity with synthetic MoSe 2 phototransistors is identified, suggesting a novel route to high-performance, multifunctional 2D material devices for future wearable sensor applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Syntheses, structures, and properties of Ag4(Mo2O5)(SeO4)2(SeO3) and Ag2(MoO3)3SeO3

    International Nuclear Information System (INIS)

    Ling Jie; Albrecht-Schmitt, Thomas E.

    2007-01-01

    Ag 4 (Mo 2 O 5 )(SeO 4 ) 2 (SeO 3 ) has been synthesized by reacting AgNO 3 , MoO 3 , and selenic acid under mild hydrothermal conditions. The structure of this compound consists of cis-MoO 2 2+ molybdenyl units that are bridged to neighboring molybdenyl moieties by selenate anions and by a bridging oxo anion. These dimeric units are joined by selenite anions to yield zigzag one-dimensional chains that extended down the c-axis. Individual chains are polar with the C 2 distortion of the Mo(VI) octahedra aligning on one side of each chain. However, the overall structure is centrosymmetric because neighboring chains have opposite alignment of the C 2 distortion. Upon heating Ag 4 (Mo 2 O 5 )(SeO 4 ) 2 (SeO 3 ) looses SeO 2 in two distinct steps to yield Ag 2 MoO 4 . Crystallographic data: (193 K; MoKα, λ=0.71073 A): orthorhombic, space group Pbcm, a=5.6557(3), b=15.8904(7), c=15.7938(7) A, V=1419.41(12), Z=4, R(F)=2.72% for 121 parameters with 1829 reflections with I>2σ(I). Ag 2 (MoO 3 ) 3 SeO 3 was synthesized by reacting AgNO 3 with MoO 3 , SeO 2 , and HF under hydrothermal conditions. The structure of Ag 2 (MoO 3 ) 3 SeO 3 consists of three crystallographically unique Mo(VI) centers that are in 2+2+2 coordination environments with two long, two intermediate, and two short bonds. These MoO 6 units are connected to form a molybdenyl ribbon that extends along the c-axis. These ribbons are further connected together through tridentate selenite anions to form two-dimensional layers in the [bc] plane. Crystallographic data: (193 K; MoKα, λ=0.71073 A): monoclinic, space group P2 1 /n, a=7.7034(5), b=11.1485(8), c=12.7500(9) A, β=105.018(1) V=1002.7(2), Z=4, R(F)=3.45% for 164 parameters with 2454 reflections with I>2σ(I). Ag 2 (MoO 3 ) 3 SeO 3 decomposes to Ag 2 Mo 3 O 10 on heating above 550 deg. C. - Graphical abstract: A view of the one-dimensional [(Mo 2 O 5 )(SeO 4 ) 2 (SeO 3 )] 4- chains that extend down the c-axis in the structure of Ag 4 (Mo 2 O 5 )(SeO 4

  10. Search for CP Violation and Measurement of the Branching Fraction in the Decay D<mn>0mn> stretchy='false'>→mo>KS>0mn>KS>0mn>

    Energy Technology Data Exchange (ETDEWEB)

    Dash, N.; Bahinipati, S.; Bhardwaj, V.; Trabelsi, K.; Adachi, I.; Aihara, H.; Al Said, S.; Asner, D. M.; Aulchenko, V.; Aushev, T.; Ayad, R.; Babu, V.; Badhrees, I.; Bakich, A. M.; Bansal, V.; Barberio, E.; Bhuyan, B.; Biswal, J.; Bobrov, A.; Bondar, A.; Bonvicini, G.; Bozek, A.; Bračko, M.; Breibeck, F.; Browder, T. E.; Červenkov, D.; Chang, M. -C.; Chekelian, V.; Chen, A.; Cheon, B. G.; Chilikin, K.; Cho, K.; Choi, Y.; Cinabro, D.; Di Carlo, S.; Doležal, Z.; Drásal, Z.; Dutta, D.; Eidelman, S.; Epifanov, D.; Farhat, H.; Fast, J. E.; Ferber, T.; Fulsom, B. G.; Gaur, V.; Gabyshev, N.; Garmash, A.; Gillard, R.; Goldenzweig, P.; Haba, J.; Hara, T.; Hayasaka, K.; Hayashii, H.; Hedges, M. T.; Hou, W. -S.; Iijima, T.; Inami, K.; Ishikawa, A.; Itoh, R.; Iwasaki, Y.; Jacobs, W. W.; Jaegle, I.; Jeon, H. B.; Jin, Y.; Joffe, D.; Joo, K. K.; Julius, T.; Kahn, J.; Kaliyar, A. B.; Karyan, G.; Katrenko, P.; Kawasaki, T.; Kiesling, C.; Kim, D. Y.; Kim, H. J.; Kim, J. B.; Kim, K. T.; Kim, M. J.; Kim, S. H.; Kim, Y. J.; Kinoshita, K.; Kodyš, P.; Korpar, S.; Kotchetkov, D.; Križan, P.; Krokovny, P.; Kuhr, T.; Kulasiri, R.; Kumar, R.; Kumita, T.; Kuzmin, A.; Kwon, Y. -J.; Lange, J. S.; Lee, I. S.; Li, C. H.; Li, L.; Li, Y.; Li Gioi, L.; Libby, J.; Liventsev, D.; Lubej, M.; Luo, T.; Masuda, M.; Matvienko, D.; Merola, M.; Miyabayashi, K.; Miyata, H.; Mizuk, R.; Mohanty, G. B.; Mohanty, S.; Moon, H. K.; Mori, T.; Mussa, R.; Nakano, E.; Nakao, M.; Nanut, T.; Nath, K. J.; Natkaniec, Z.; Nayak, M.; Niiyama, M.; Nisar, N. K.; Nishida, S.; Ogawa, S.; Okuno, S.; Ono, H.; Pakhlov, P.; Pakhlova, G.; Pal, B.; Pardi, S.; Park, C. -S.; Park, H.; Paul, S.; Pedlar, T. K.; Pesántez, L.; Pestotnik, R.; Piilonen, L. E.; Prasanth, K.; Ritter, M.; Rostomyan, A.; Sahoo, H.; Sakai, Y.; Sandilya, S.; Santelj, L.; Sanuki, T.; Sato, Y.; Savinov, V.; Schneider, O.; Schnell, G.; Schwanda, C.; Schwartz, A. J.; Seino, Y.; Senyo, K.; Sevior, M. E.; Shebalin, V.; Shen, C. P.; Shibata, T. -A.; Shiu, J. -G.; Shwartz, B.; Simon, F.; Sokolov, A.; Solovieva, E.; Starič, M.; Strube, J. F.; Stypula, J.; Sumisawa, K.; Sumiyoshi, T.; Takizawa, M.; Tamponi, U.; Tanida, K.; Tenchini, F.; Uchida, M.; Uglov, T.; Unno, Y.; Uno, S.; Urquijo, P.; Usov, Y.; Van Hulse, C.; Varner, G.; Vorobyev, V.; Vossen, A.; Waheed, E.; Wang, C. H.; Wang, M. -Z.; Wang, P.; Watanabe, M.; Watanabe, Y.; Widmann, E.; Williams, K. M.; Won, E.; Yamashita, Y.; Ye, H.; Yelton, J.; Yook, Y.; Yuan, C. Z.; Yusa, Y.; Zhang, Z. P.; Zhilich, V.; Zhukova, V.; Zhulanov, V.; Zupanc, A.

    2017-10-01

    We report a study of the decay D<mn>0mn> stretchy='false'>→mo>KS>0mn>KS>0mn> using 921 fb-1 of data collected at or near the Υ(4S) and Υ(5S) resonances with the Belle detector at the KEKB asymmetric energy e+e- collider. The measured time-integrated CP asymmetry is ACP(D<mn>0mn> stretchy='false'>→mo>KS>0mn>KS>0mn>) = (-0.02 ± 1.53 ± 0.02 ± 0.17)%, and the branching fraction is B(D<mn>0mn> stretchy='false'>→mo>KS>0mn>KS>0mn>) = (1.321 ± 0.023 ± 0.036 ± 0.044) × 10-4, where the first uncertainty is statistical, the second is systematic, and the third is due to the normalization mode (D<mn>0mn> stretchy='false'>→mo>KS>0mn>π0). These results are significantly more precise than previous measurements available for this mode. The ACP measurement is consistent with the standard model expectation.

  11. Molybdenum isotopes in modern marine hydrothermal Fe/Mn deposits: Implications for Archean and Paleoproterozoic Mo cycles

    Science.gov (United States)

    Goto, K. T.; Hein, J. R.; Shimoda, G.; Aoki, S.; Ishikawa, A.; Suzuki, K.; Gordon, G. W.; Anbar, A. D.

    2016-12-01

    Molybdenum isotope (δ98/95Mo) variations recorded in Archean and Paleoproterozoic Fe/Mn-rich sediments have been used to constrain ocean redox conditions at the time of deposition (Canfield et al., 2013 PNAS; Planavsky et al., 2014 Nat. Geo.; Kurzweil et al., 2015 GCA). However, except for hydrogenous Fe-Mn crusts (Siebert et al., 2003), δ98/95Mo variation of modern Fe and Mn oxide deposits has been poorly investigated. Marine hydrothermal systems are thought to be the major source of Fe and Mn in Archean and Paleoproterozoic Fe- and Mn-rich sediments. Hence, to accurately interpret Mo isotope data of those ancient sedimentary rocks, it is important to evaluate the possible influence of hydrothermally derived Mo on δ98/95Mo of modern Fe- and Mn-rich sediments. In this study, we analyzed Mo isotopic compositions of one hydrothermal Fe oxide and 15 Mn oxides from five different hydrothermal systems in the modern ocean. The Fe oxide is composed mainly of goethite, and has a δ98/95Mo of 0.7‰, which is 1.4‰ lighter than that of present-day seawater. The observed offset is similar to isotope fractionation observed during adsorption experiments of Mo on goethite (Δ98/95Mogoethite-solution = -1.4 ± 0.5%; Goldberg et al., 2009 GCA). The 15 hydrothermal Mn oxides show large variations in δ98/95Mo ranging from -1.7 to 0.5‰. However, most of the values are similar to those of modern hydrogenous Fe-Mn crusts (Siebert et al., 2003 EPSL), and fall within the range of estimated δ98/95Mo of Mn oxides precipitated from present-day seawater using the isotope offset reported from adsorption experiments (Δ98/95Mo = -2.7 ± 0.3‰; Wasylenki et al., 2008 GCA). These findings indicate that seawater is the dominant source of Mo for modern hydrothermal Fe and Mn deposits. However, the observed large variation indicates that the contribution Mo from local hydrothermal systems is not negligible. The oceanic Mo inventory during the Archean and Paleoproterozoic is thought to be

  12. Generator of 99m Tc with MnO2 as support of 99 Mo

    International Nuclear Information System (INIS)

    Granados C, F.; Serrano G, J.

    2002-01-01

    The generator of 99m Tc with MnO 2 as support of 99 Mo was studied. By mean of static experiments the retention of 99 Mo in MnO 2 in function of the stirring time and of the p H value of the solution of 99 Mo. It was found that the 99 Mo presents 100% of retention in MnO 2 in the rank of p H 3-11 and the balance was reached before of 10 minutes. In dynamic conditions the retention of 99 Mo in MnO 2 at p H=5 was also higher: 99.72%. The generated 99m Tc can be separated from 99 Mo, adsorbed in MnO 2 packed in the column, using distilled water at p H=5 or NaCl solution at 0.9%. With saline solution the elution yields were greater than 80% and only an aliquot of 5 ml was necessary for obtaining this yield. The better results were obtained when the column was packed with 1 g of MnO 2 . The water and the saline solution were passed through of the column with a flux of 1.25 ml/min. (Author)

  13. Lattice structures and electronic properties of MO/MoSe2 interface from first-principles calculations

    Science.gov (United States)

    Zhang, Yu; Tang, Fu-Ling; Xue, Hong-Tao; Lu, Wen-Jiang; Liu, Jiang-Fei; Huang, Min

    2015-02-01

    Using first-principles plane-wave calculations within density functional theory, we theoretically studied the atomic structure, bonding energy and electronic properties of the perfect Mo (110)/MoSe2 (100) interface with a lattice mismatch less than 4.2%. Compared with the perfect structure, the interface is somewhat relaxed, and its atomic positions and bond lengths change slightly. The calculated interface bonding energy is about -1.2 J/m2, indicating that this interface is very stable. The MoSe2 layer on the interface has some interface states near the Fermi level, the interface states are mainly caused by Mo 4d orbitals, while the Se atom almost have no contribution. On the interface, Mo-5s and Se-4p orbitals hybridize at about -6.5 to -5.0 eV, and Mo-4d and Se-4p orbitals hybridize at about -5.0 to -1.0 eV. These hybridizations greatly improve the bonding ability of Mo and Se atom in the interface. By Bader charge analysis, we find electron redistribution near the interface which promotes the bonding of the Mo and MoSe2 layer.

  14. Sonochemical synthesis, characterization, and electrochemical properties of MnMoO4 nanorods for supercapacitor applications

    International Nuclear Information System (INIS)

    Veerasubramani, Ganesh Kumar; Krishnamoorthy, Karthikeyan; Sivaprakasam, Radhakrishnan; Kim, Sang Jae

    2014-01-01

    In this article, we reported the preparation of manganese molybdate (MnMoO 4 ) nanorods by a facile sonochemical method and investigated its electrochemical properties for supercapacitor applications. The microstructure, surface morphology and composition were characterized by using field emission scanning electron microscope (FE-SEM), high resolution-transmission electron microscopy (HR-TEM), X-ray diffraction analysis (XRD), Raman spectroscopy and X-ray photo electron microscopy (XPS). The cyclic voltammetry (CV) curves of sonochemically synthesized α-MnMoO 4 nanorods revealed the presence of redox pairs suggesting the pseudocapacitive nature of MnMoO 4 . A maximum specific capacitance of the α-MnMoO 4 nanorods was about 168.32 F g −1 as observed from the galvanostatic charge–discharge (GCD) analysis at a constant current density of 0.5 mA cm −2 . Long term cyclic stability study revealed that about 96% of initial capacitance was retained after 2000 cycles. - Highlights: • MnMoO 4 nanorods were synthesized by sonochemical method. • FE-SEM studies show the rod like morphology of MnMoO 4 . • XRD studies show the presence of monoclinic phase of α-MnMoO 4 . • Specific capacitance of 168.32 F g −1 was achieved using charge–discharge analysis

  15. Resonantly enhanced spin-lattice relaxation of Mn2 + ions in diluted magnetic (Zn,Mn)Se/(Zn,Be)Se quantum wells

    Science.gov (United States)

    Debus, J.; Ivanov, V. Yu.; Ryabchenko, S. M.; Yakovlev, D. R.; Maksimov, A. A.; Semenov, Yu. G.; Braukmann, D.; Rautert, J.; Löw, U.; Godlewski, M.; Waag, A.; Bayer, M.

    2016-05-01

    The dynamics of spin-lattice relaxation in the magnetic Mn2 + ion system of (Zn,Mn)Se/(Zn,Be)Se quantum-well structures are studied using optical methods. Pronounced cusps are found in the giant Zeeman shift of the quantum-well exciton photoluminescence at specific magnetic fields below 10 T, when the Mn spin system is heated by photogenerated carriers. The spin-lattice relaxation time of the Mn ions is resonantly accelerated at the cusp magnetic fields. Our theoretical analysis demonstrates that a cusp occurs at a spin-level mixing of single Mn2 + ions and a quick-relaxing cluster of nearest-neighbor Mn ions, which can be described as intrinsic cross-relaxation resonance within the Mn spin system.

  16. Synthesis and nonlinear optical property of polycrystalline MnTeMoO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Chengguo [Yibin University, Key Laboratory of Computational Physics of Sichuan Province, Yibin (China); Yibin University, School of Physics and Electronic Engineering, Yibin (China)

    2017-04-15

    Polycrystalline MnTeMoO{sub 6} powder has been synthesized by a new approach that MnO{sub 2} is used as the manganese source. The transformation mechanism of manganese ions in the new approach has been discussed. The nonlinear optical property of polycrystalline MnTeMoO{sub 6} has been investigated, and compared with single-crystalline samples. The transformation Mn{sup 4+} → Mn{sup 2+} may be formed directly without stable intermediates, and TeO{sub 2} may serve as catalyst. The SHG response of polycrystalline MnTeMoO{sub 6} powder is worse than that of single-crystalline powder in the same particle size distribution as its pseudo-size. The results indicate that it should pay special attention with the pseudo-size of polycrystalline powder when the potential nonlinear optical materials are screened by powder second harmonic generation measurements. (orig.)

  17. Controlled formation of MoSe{sub 2} by MoN{sub x} thin film as a diffusion barrier against Se during selenization annealing for CIGS solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Chan-Wook [School of Chemical Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of); Cheon, Taehoon [School of Materials Science and Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of); Center for Core Research Facilities, DaeguGyeongbuk Institute of Science & Technology, Daegu (Korea, Republic of); Kim, Hangil [School of Materials Science and Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of); Kwon, Min-Su [School of Chemical Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of); Kim, Soo-Hyun [School of Materials Science and Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of)

    2015-09-25

    Highlights: • Mo/MoN{sub x}/Mo multilayer was investigated as a back contact for CIGS solar cell. • The MoN{sub x} protected the underlying Mo layer during high temperature selenization. • The formation of MoSe{sub 2} layer was precisely controlled. • The diffusion barrier performance of MoN{sub x} against Se was evaluated using TEM analysis. - Abstract: This study investigated the interfacial reactions and electrical properties of a Mo single layer and Mo/MoN{sub x}/Mo multilayer during high temperature selenization annealing. The Mo single layer was converted easily to MoSe{sub 2}, which was 7 times thicker than the Mo layer consumed ∼900 nm, by selenization at 460 °C for 10 min and the sheet resistance increased 8 fold compared to that of the as-deposited Mo film. On the other hand, in the Mo/MoN{sub x}/Mo structure, transmission electron microscopy (TEM) showed that the MoSe{sub 2} transformation was localized only in the top Mo layer and the bottom Mo layer was completely unaffected, even after selenization at 560 °C. The sheet resistance of the multilayer was relatively unchanged by selenization. This suggests that the MoN{sub x} layer performed well as a diffusion barrier against Se and the thickness of MoSe{sub 2} can be controlled precisely by adjusting the top Mo layer thickness. Furthermore, TEM and energy dispersive spectroscopy analysis showed that the selenized multilayer consisted of MoSe{sub 2}/Mo/MoN{sub x}/Mo, in which the top Mo layer of 60 nm was not fully converted to MoSe{sub 2} and 20 nm was left unreacted. The residual Mo interlayer located at the interface of MoSe{sub 2} and MoN{sub x} is believed to be beneficial for the ohmic contact of the selenized multilayer.

  18. Generator of {sup 99m} Tc with MnO{sub 2} as support of {sup 99} Mo; Generador de {sup 99m} Tc con MnO{sub 2} como soporte del {sup 99}Mo

    Energy Technology Data Exchange (ETDEWEB)

    Granados C, F.; Serrano G, J. [Departamento de Quimica, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2002-07-01

    The generator of {sup 99m} Tc with MnO{sub 2} as support of {sup 99} Mo was studied. By mean of static experiments the retention of {sup 99} Mo in MnO{sub 2} in function of the stirring time and of the p H value of the solution of {sup 99} Mo. It was found that the {sup 99} Mo presents 100% of retention in MnO{sub 2} in the rank of p H 3-11 and the balance was reached before of 10 minutes. In dynamic conditions the retention of {sup 99} Mo in MnO{sub 2} at p H=5 was also higher: 99.72%. The generated {sup 99m} Tc can be separated from {sup 99} Mo, adsorbed in MnO{sub 2} packed in the column, using distilled water at p H=5 or NaCl solution at 0.9%. With saline solution the elution yields were greater than 80% and only an aliquot of 5 ml was necessary for obtaining this yield. The better results were obtained when the column was packed with 1 g of MnO{sub 2}. The water and the saline solution were passed through of the column with a flux of 1.25 ml/min. (Author)

  19. Low temperature magnetic structure of MnSe

    Indian Academy of Sciences (India)

    Abstract. In this paper we report low temperature neutron diffraction studies on MnSe in order to understand the anomalous behaviour of their magnetic and transport prop- erties. Our study indicates that at low temperatures MnSe has two coexisting crystal structures, high temperature NaCl and hexagonal NiAs. NiAs phase ...

  20. Influence of Mo/MoSe{sub 2} microstructure on the damp heat stability of the Cu(In,Ga)Se{sub 2} back contact molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Theelen, Mirjam, E-mail: mirjam.theelen@tno.nl [TNO Solliance, Thin Film Technology, High Tech Campus 21, 5656 AE Eindhoven (Netherlands); Delft University of Technology, Photovoltaic Materials and Devices, Mekelweg 4, 2628 CD Delft (Netherlands); Harel, Sylvie [Institut des Matériaux Jean Rouxel (IMN)-UMR 6502, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3 (France); Verschuren, Melvin [TNO Solliance, Thin Film Technology, High Tech Campus 21, 5656 AE Eindhoven (Netherlands); Tomassini, Mathieu [Institut des Matériaux Jean Rouxel (IMN)-UMR 6502, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3 (France); Hovestad, Arjan [TNO Solliance, Thin Film Technology, High Tech Campus 21, 5656 AE Eindhoven (Netherlands); Barreau, Nicolas [Institut des Matériaux Jean Rouxel (IMN)-UMR 6502, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3 (France); Berkum, Jurgen van [Philips Innovation Services, High Tech Campus 11, 5656 AE Eindhoven (Netherlands); Vroon, Zeger [TNO Solliance, Thin Film Technology, High Tech Campus 21, 5656 AE Eindhoven (Netherlands); Zeman, Miro [Delft University of Technology, Photovoltaic Materials and Devices, Mekelweg 4, 2628 CD Delft (Netherlands)

    2016-08-01

    The degradation behavior of Mo/MoSe{sub 2} layers have been investigated using damp heat exposure. The two studied molybdenum based films with different densities and microstructures were obtained by lifting off Cu(In,Ga)Se{sub 2} layers from a bilayer molybdenum stack on soda lime glass. Hereby, a glass/Mo/MoSe{sub 2} was obtained, which resembles the back contact as present in Cu(In,Ga)Se{sub 2} solar cells. The samples were degraded for 150 h under standard damp heat conditions and analyzed before, during and after degradation. It was observed that the degradation resulted in the formation of needles and molybdenum oxide layers near the glass/Mo and the Mo/Cu(In,Ga)Se{sub 2} interfaces. X-ray Photoelectron Spectroscopy measurements have shown that the sodium was also present at the surface of the degraded material and it is proposed that the degraded material consists mostly of MoO{sub 3} with intercalated Na{sup +}. This element has likely migrated from the soda lime glass. This intercalation process could have led to the formation of Na{sub x}MoO{sub 3} ‘molybdenum bronze’ following this redox reaction: xNa{sup +} + MoO{sub 3} + xe{sup −} ↔ Na{sub x}MoO{sub 3} It is proposed that the formed oxide layer contains Na{sub x}MoO{sub 3} with different Na{sup +} contents and different grades of conductivity. This intercalation process can also explain the high mobility of Na{sup +} via the grain boundaries in molybdenum. It was also observed that the molybdenum film with a top layer deposited at a high pressure is more susceptible for damp heat degradation. - Highlights: • SLG/high pressure Mo/low pressure Mo/MoSe{sub 2} stacks were exposed to damp heat. • Molybdenum deposited at low pressure retained the best reflectivity and conductivity. • Damp heat exposure leads to a Na{sub x}MoO{sub 3}/Mo multilayer structure. • The Na{sub x}MoO{sub 3} probably consists of Na{sup +} intercalated in a (reduced) MoO{sub 3} matrix. • Intercalation can explain the

  1. Interaction in the NaIn(MoO4)2 - AMoO4 (A = Mg, Mn) systems

    International Nuclear Information System (INIS)

    Kotova, I.Yu.; Kozhevnikova, N.M.

    2001-01-01

    The results of investigation into NaIn(MoO 4 ) 2 - AMoO 4 (A = Mg, Mn) quasibinary cross-sections by means of X-ray diffraction and differential thermal analysis are presented. Conducted researches revealed that compounds NaMg 3 In(MoO 4 ) and NaMn 3 In(MoO 4 ) melting incongruently at 990 Deg C and 940 Deg C accordingly were formed in the NaIn(MoO 4 ) - AMoO 4 (A = Mg, Mn) systems. The data of initiation of X-ray diffraction pattern of NaMg 3 In(MoO 4 ) 5 are presented. The temperature dependences of conductivity, dielectric permeability and tangent of dielectric losses indicative on ionic-electronic nature conductivity are determined. Activation energy of conductivity in the Mg - Mn row changes moderately - from 9.91 till 5.71 eV [ru

  2. V1.42In1.83Mo15Se19

    Directory of Open Access Journals (Sweden)

    Michel Potel

    2010-10-01

    Full Text Available The structure of the title compound, vanadium indium pentadecamolybdenum nonadecaselenide, V1.42In1.83Mo15Se19, is isotypic with In2.9Mo15Se19 [Grüttner et al. (1979. Acta Cryst. B35, 285–292]. It is characterized by two cluster units Mo6Sei8Sea6 and Mo9Sei11Sea6 (where i represents inner and a apical atoms that are present in a 1:1 ratio. The cluster units are centered at Wyckoff positions 2b and 2c and have point-group symmetry overline{3} and overline{6}, respectively. The clusters are interconnected through additional Mo—Se bonds. In the title compound, the V3+ cations replace the trivalent indium atoms present in In2.9Mo15Se19, and a deficiency is observed on the monovalent indium site. One Mo, one Se and the V atom are situated on mirror planes, and two other Se atoms and the In atom are situated on threefold rotation axes.

  3. Monolayer MoSe 2 Grown by Chemical Vapor Deposition for Fast Photodetection

    KAUST Repository

    Chang, Yung-Huang

    2014-08-26

    Monolayer molybdenum disulfide (MoS2) has become a promising building block in optoelectronics for its high photosensitivity. However, sulfur vacancies and other defects significantly affect the electrical and optoelectronic properties of monolayer MoS2 devices. Here, highly crystalline molybdenum diselenide (MoSe2) monolayers have been successfully synthesized by the chemical vapor deposition (CVD) method. Low-temperature photoluminescence comparison for MoS2 and MoSe 2 monolayers reveals that the MoSe2 monolayer shows a much weaker bound exciton peak; hence, the phototransistor based on MoSe2 presents a much faster response time (<25 ms) than the corresponding 30 s for the CVD MoS2 monolayer at room temperature in ambient conditions. The images obtained from transmission electron microscopy indicate that the MoSe exhibits fewer defects than MoS2. This work provides the fundamental understanding for the differences in optoelectronic behaviors between MoSe2 and MoS2 and is useful for guiding future designs in 2D material-based optoelectronic devices. © 2014 American Chemical Society.

  4. Synthesis of highly luminescent Mn:ZnSe/ZnS nanocrystals in aqueous media

    International Nuclear Information System (INIS)

    Fang Zheng; Wu Ping; Zhong Xinhua; Yang Yongji

    2010-01-01

    High-quality water-dispersible Mn 2+ -doped ZnSe core/ZnS shell (Mn:ZnSe/ZnS) nanocrystals have been synthesized directly in aqueous media. Overcoating a high bandgap ZnS shell around the Mn:ZnSe cores can bring forward an efficient energy transfer from the ZnSe host nanocrystals to the dopant Mn. The quantum yields of the dopant Mn photoluminescence in the as-prepared water-soluble Mn:ZnSe/ZnS core/shell nanocrystals can be up to 35 ± 5%. The optical features and structure of the obtained Mn:ZnSe/ZnS core/shell nanocrystals have been characterized by UV-vis, PL spectroscopy, TEM, XRD and ICP elementary analysis. The influences of various experimental variables, including the Mn concentration, the Se/Zn molar ratio as well as the kind and amount of capping ligand used in the core production and shell deposition process, on the luminescent properties of the obtained Mn:ZnSe/ZnS nanocrystals have been systematically investigated.

  5. Enhanced field emission behavior of layered MoSe2

    International Nuclear Information System (INIS)

    Suryawanshi, Sachin R; Pawbake, Amit S; Jadkar, Sandesh R; More, Mahendra A; Pawar, Mahendra S; Late, Dattatray J

    2016-01-01

    Herein, we report one step facile chemical vapor deposition method for synthesis of single-layer MoSe 2 nanosheets with average lateral dimension ∼60 μm on 300 nm SiO 2 /Si and n-type silicon substrates and field emission investigation of MoSe 2 /Si at the base pressure of ∼1 × 10 −8 mbar. The morphological and structural analyses of the as-deposited single-layer MoSe 2 nanosheets were carried out using an optical microscopy, Raman spectroscopy and atomic force microscopy. Furthermore, the values of turn-on and threshold fields required to extract an emission current densities of 1 and 10 μA cm −2 , are found to be ∼1.9 and ∼2.3 V μm −1 , respectively. Interestingly, the MoSe 2 nanosheet emitter delivers maximum field emission current density of ∼1.5 mA cm −2 at a relatively lower applied electric field of ∼3.9 V μm −1 . The long term operational current stability recorded at the preset values of 35 μA over 3 hr duration and is found to be very good. The observed results demonstrates that the layered MoSe 2 nanosheet based field emitter can open up many opportunities for their potential application as an electron source in flat panel display, transmission electron microscope, and x-ray generation. Thus, the facile one step synthesis approach and robust nature of single-layer MoSe 2 nanosheets emitter can provide prospects for the future development of practical electron sources. (paper)

  6. Thermally stimulated properties in ZnSe:Tb and ZnSe:(Mn, Tb) phosphors

    Science.gov (United States)

    Mishra, A. K.; Mishra, S. K.; Pandey, S. P.; Lakshmi Mishra, Kshama

    2018-02-01

    Thermoluminescence studies were performed of ZnSe:Tb and ZnSe:(Mn, Tb) phosphors. A method of preparation for ZnSe phosphors doped with Tb and (Mn, Tb) has been discussed. The thermoluminescence (TL) properties of these phosphors have been studied from 100 to 370 K temperature after exciting by UV radiation (365 nm) at three uniform heating rates 0.4, 0.6 and 0.9 K/s. The trapping parameters like trap depth, lifetime of electrons and capture cross-section have also been determined using various methods.

  7. Hydrothermal syntheses and characterization of two layered molybdenum selenites, Rb2(MoO3)3SeO3 and Tl2(MoO3)3SeO3

    International Nuclear Information System (INIS)

    Dussack, L.L.; Harrison, W.T.A.; Jacobson, A.J.

    1996-01-01

    The hydrothermal syntheses of Rb 2 (MoO 3 ) 3 SeO 3 , and Tl 2 (MoO 3 ) 3 SeO 3 are described. These compounds have structures built up from hexagonal-WO 3 -type sheets and are isostructural with the previously reported Cs 2 (MoO 3 ) 3 SeO 3 and (NH 4 ) 2 (MoO 3 ) 3 SeO 3 . Powder X-ray, thermogravimetric, and spectroscopic data are presented and discussed

  8. Nonlinear optical characteristics of monolayer MoSe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Le, Chinh Tam; Ullah, Farman; Senthilkumar, Velusamy; Kim, Yong Soo [Department of Physics and Energy Harvest Storage Research Center, University of Ulsan (Korea, Republic of); Clark, Daniel J.; Jang, Joon I. [Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, NY (United States); Sim, Yumin; Seong, Maeng-Je [Department of Physics, Chung-Ang University, Seoul (Korea, Republic of); Chung, Koo-Hyun [School of Mechanical Engineering, University of Ulsan (Korea, Republic of); Park, Hyoyeol [Electronics, Communication and Semiconductor Applications Department, Ulsan College (Korea, Republic of)

    2016-08-15

    In this study, we utilized picosecond pulses from an Nd:YAG laser to investigate the nonlinear optical characteristics of monolayer MoSe{sub 2}. Two-step growth involving the selenization of pulsed-laser-deposited MoO{sub 3} film was employed to yield the MoSe{sub 2} monolayer on a SiO{sub 2}/Si substrate. Raman scattering, photoluminescence (PL) spectroscopy, and atomic force microscopy verified the high optical quality of the monolayer. The second-order susceptibility χ{sup (2)} was calculated to be ∝50 pm V{sup -1} at the second harmonic wavelength λ{sub SHG} ∝810 nm, which is near the optical gap of the monolayer. Interestingly, our wavelength-dependent second harmonic scan can identify the bound excitonic states including negatively charged excitons much more efficiently, compared with the PL method at room temperature. Additionally, the MoSe{sub 2} monolayer exhibits a strong laser-induced damage threshold ∝16 GW cm{sup -2} under picosecond-pulse excitation{sub .} Our findings suggest that monolayer MoSe{sub 2} can be considered as a promising candidate for high-power, thin-film-based nonlinear optical devices and applications. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Preparation and characterization of Bi26-2xMn2xMo10O69-d and Bi26.4Mn0.6Mo10-2yMe2yO69-d (Me = V, Fe Solid Solutions

    Directory of Open Access Journals (Sweden)

    Z. A. Mikhaylovskaya

    2017-09-01

    Full Text Available Single phase samples of bismuth molybdate, Bi26Mo10O69, doped with Mn on the bismuth sublattice and V, Fe on the molybdenum sublattice were found to crystallize in the triclinic Bi26Mo10O69 structure at low doping levels and in the monoclinic Bi26Mo10O69 structure - at higher dopant concentration. The assumption that all Mn ions have an oxidation state of +2 was confirmed by means of magnetic measurement results analysis using Curie-Weiss law. Conductivity was investigated using impedance spectroscopy. The conductivity of Bi26.4Mn0.6Mo9.6Fe0.4O69-d was 1.2*10-2 S*cm-1 at 973 K and 2.2*10-4 S*cm-1 at 623 K, and the conductivity of Bi26.4Mn0.6Mo9.2V0.8O69-d was 2.2*10-3 S*cm-1 at 973 K and 2.2*10-5 S*cm-1 at 623 K.

  10. Vertical MoSe2-MoO x p-n heterojunction and its application in optoelectronics

    Science.gov (United States)

    Chen, Xiaoshuang; Liu, Guangbo; Hu, Yunxia; Cao, Wenwu; Hu, PingAn; Hu, Wenping

    2018-01-01

    The hybrid n-type 2D transition-metal dichalcogenide (TMD)/p-type oxide van der Waals (vdW) heterojunction nanosheets consist of 2D layered MoSe2 (the n-type 2D material) and MoO x (the p-type oxide) which are grown on SiO2/Si substrates for the first time via chemical vapor deposition technique, displaying the regular hexagon structures with the average length dimension of sides of ˜8 μm. Vertical MoSe2-MoO x p-n heterojunctions demonstrate obviously current-rectifying characteristic, and it can be tuned via gate voltage. What is more, the photodetector based on vertical MoSe2-MoO x heterojunctions displays optimal photoresponse behavior, generating the responsivity, detectivity, and external quantum efficiency to 3.4 A W-1, 0.85 × 108 Jones, and 1665.6%, respectively, at V ds = 5 V with the light wavelength of 254 nm under 0.29 mW cm-2. These results furnish a building block on investigating the flexible and transparent properties of vdW and further optimizing the structure of the devices for better optoelectronic and electronic performance.

  11. Mo1-xWxSe2-Based Schottky Junction Photovoltaic Cells.

    Science.gov (United States)

    Yi, Sum-Gyun; Kim, Sung Hyun; Park, Sungjin; Oh, Donggun; Choi, Hwan Young; Lee, Nara; Choi, Young Jai; Yoo, Kyung-Hwa

    2016-12-14

    We developed Schottky junction photovoltaic cells based on multilayer Mo 1-x W x Se 2 with x = 0, 0.5, and 1. To generate built-in potentials, Pd and Al were used as the source and drain electrodes in a lateral structure, and Pd and graphene were used as the bottom and top electrodes in a vertical structure. These devices exhibited gate-tunable diode-like current rectification and photovoltaic responses. Mo 0.5 W 0.5 Se 2 Schottky diodes with Pd and Al electrodes exhibited higher photovoltaic efficiency than MoSe 2 and WSe 2 devices with Pd and Al electrodes, likely because of the greater adjusted band alignment in Mo 0.5 W 0.5 Se 2 devices. Furthermore, we showed that Mo 0.5 W 0.5 Se 2 -based vertical Schottky diodes yield a power conversion efficiency of ∼16% under 532 nm light and ∼13% under a standard air mass 1.5 spectrum, demonstrating their remarkable potential for photovoltaic applications.

  12. Correlation between lateral size and gas sensing performance of MoSe2 nanosheets

    Science.gov (United States)

    Zhang, Shaolin; Nguyen, Thuy Hang; Zhang, Weibin; Park, Youngsin; Yang, Woochul

    2017-10-01

    We demonstrate a facile synthetic method to prepare lateral size controlled molybdenum diselenide (MoSe2) nanosheets using liquid phase exfoliated few-layer MoSe2 nanosheets as a starting material. By precisely controlling the centrifugation condition, preparation of MoSe2 nanosheets with a narrow size distribution ranging from several hundred nanometers to several micrometers could be realized. The accurate size control of MoSe2 nanosheets offers us a great opportunity to examine the size dependent sensing properties. The sensing test results demonstrate that the MoSe2 nanosheets provide competitive advantages compared with conventional graphene based sensors. A tradeoff phenomenon on sensing response and recovery as the lateral size of MoSe2 nanosheets varies is observed. First principles calculations reveal that the ratio of edge-surface sites is responsible for this phenomenon. The correlation between the lateral size and gas sensing performance of MoSe2 nanosheets is established.

  13. Two new octahedral/pyramidal frameworks containing both cation channels and lone-pair channels: syntheses and structures of Ba2MnIIMn2III(SeO3)6 and PbFe2(SeO3)4

    International Nuclear Information System (INIS)

    Johnston, Magnus G.; Harrison, William T.A.

    2004-01-01

    The hydrothermal syntheses, single crystal structures, and some properties of Ba 2 Mn II Mn 2 III (SeO 3 ) 6 and PbFe 2 (SeO 3 ) 4 are reported. These related phases contain three-dimensional frameworks of vertex (FeO 6 ) and vertex/edge linked (MnO 6 ) octahedra and SeO 3 pyramids. In each case, the MO 6 /SeO 3 framework encloses two types of 8 ring channels, one of which encapsulates the extra-framework cations and one of which provides space for the Se IV lone pairs. Crystal data: Ba 2 Mn 3 (SeO 3 ) 6 , M r =1201.22, monoclinic, P2 1 /c (No. 14), a=5.4717 (3)A, b=9.0636 (4)A, c=17.6586 (9)A, β=94.519 (1) o , V=873.03 (8)A 3 , Z=2, R(F)=0.031, wR(F 2 )=0.070; PbFe 2 (SeO 3 ) 4 , M r =826.73, triclinic, P1-bar (No. 2), a=5.2318 (5)A, b=6.7925 (6)A, c=7.6445 (7)A, α=94.300 (2) o , β=90.613 (2) o , γ=95.224 (2) o , V=269.73 (4)A 3 , Z=1, R(F)=0.051, wR(F 2 )=0.131

  14. Layer-by-layer thinning of MoSe_2 by soft and reactive plasma etching

    International Nuclear Information System (INIS)

    Sha, Yunfei; Xiao, Shaoqing; Zhang, Xiumei; Qin, Fang; Gu, Xiaofeng

    2017-01-01

    Highlights: • Soft plasma etching technique using SF_6 + N_2 as precursors for layer-by-layer thinning of MoSe_2 was adopted in this work. • Optical microscopy, Raman, photoluminescence and atomic force microscopy measurements were used to confirm the thickness change. • Layer-dependent vibrational and photoluminescence spectra of the etched MoSe_2 were also demonstrated. • Equal numbers of MoSe_2 layers can be removed uniformly without affecting the underlying SiO_2 substrate and the remaining MoSe_2 layers. - Abstract: Two-dimensional (2D) transition metal dichalcogenides (TMDs) like molybdenum diselenide (MoSe_2) have recently gained considerable interest since their properties are complementary to those of graphene. Unlike gapless graphene, the band structure of MoSe_2 can be changed from the indirect band gap to the direct band gap when MoSe_2 changed from bulk material to monolayer. This transition from multilayer to monolayer requires atomic-layer-precision thining of thick MoSe_2 layers without damaging the remaining layers. Here, we present atomic-layer-precision thinning of MoSe_2 nanaosheets down to monolayer by using SF_6 + N_2 plasmas, which has been demonstrated to be soft, selective and high-throughput. Optical microscopy, atomic force microscopy, Raman and photoluminescence spectra suggest that equal numbers of MoSe_2 layers can be removed uniformly regardless of their initial thickness, without affecting the underlying SiO_2 substrate and the remaining MoSe_2 layers. By adjusting the etching rates we can achieve complete MoSe_2 removal and any disired number of MoSe_2 layers including monolayer. This soft plasma etching method is highly reliable and compatible with the semiconductor manufacturing processes, thereby holding great promise for various 2D materials and TMD-based devices.

  15. Synthesis and Fluorescence Property of Mn-Doped ZnSe Nanowires

    Directory of Open Access Journals (Sweden)

    Dongmei Han

    2010-01-01

    Full Text Available Water-soluble Mn-doped ZnSe luminescent nanowires were successfully prepared by hydrothermal method without any heavy metal ions and toxic reagents. The morphology, composition, and property of the products were investigated. The experimental results showed that the Mn-doped ZnSe nanowires were single well crystallized and had a zinc blende structure. The average length of the nanowires was about 2-3 μm, and the diameter was 80 nm. With the increase of Mn2+-doped concentration, the absorbance peak showed large difference. The UV-vis absorbance spectrum showed that the Mn-doped ZnSe nanowires had a sharp absorption band appearing at 360 nm. The PL spectrum revealed that the nanowires had two distinct emission bands centered at 432 and 580 nm.

  16. MoSe2 modified TiO2 nanotube arrays with superior photoelectrochemical performance

    Science.gov (United States)

    Zhang, Yaping; Zhu, Haifeng; Yu, Lianqing; He, Jiandong; Huang, Chengxing

    2018-04-01

    TiO2 nanotube arrays (TNTs) are first prepared by anodization Ti foils in ethylene glycol electrolyte. Then, MoSe2 deposites electrochemically on TNTs. The as-synthesized MoSe2/TiO2 composite has a much higher photocurrent density of 1.07 mA cm‑2 at 0 V than pure TNTs of 0.38 mA cm‑2, which suggests that the MoSe2/TiO2 composite film has optimum photoelectrocatalysis properties. The electron transport resistances of the MoSe2/TiO2 decreases to half of pure TiO2, at 295.6 ohm/cm2. Both photocurrent-time and Mott-Schottky plots indicate MoSe2 a p-type semiconductor characteristics. MoSe2/TiO2 composite can achieve a maximum 5 orders of magnitude enhancement in carrier density (4.650 × 1027 cm‑3) than that of pure TiO2 arrays. It can be attributed to p-n heterojunction formed between MoSe2 and TiO2, and the composite can be potentially applied in photoelectrochemical, photocatalysis fields.

  17. Experimental study on the microstructure evolution of 55SiMnMo

    International Nuclear Information System (INIS)

    Zhao, Y Q; Liu, F F; Wang, X G; Qi, H Y; Ma, Z H

    2015-01-01

    Isothermal compressive experiments on 55SiMnMo steel were carried out with the Gleeble 3500 hot-simulation machine. High temperature flow stress-strain curves were measured over the deformation temperature range of 950 to 1050 °C and a strain rate from 0.01 to 10 s -1 . Experimental results revealed that the peak stress decreases with increasing deformation temperature and decreasing strain rate. In addition, when the deformation temperature T ≥ 1000°C, and the strain rate ≤ 0.1 s -1 , the dynamic recrystallization of 55SiMnMo steel occurs. The stress and strain constitutive models and austenite recrystallization model were constructed to form the foundation for studying the forming process of drill rods. (paper)

  18. Large-area and highly crystalline MoSe2 for optical modulator

    Science.gov (United States)

    Yin, Jinde; Chen, Hao; Lu, Wei; Liu, Mengli; Li, Irene Ling; Zhang, Min; Zhang, Wenfei; Wang, Jinzhang; Xu, Zihan; Yan, Peiguang; Liu, Wenjun; Ruan, Shuangchen

    2017-12-01

    Transition metal dichalcogenides (TMDs) have been successfully used as broadband optical modulator materials for pulsed fiber laser systems. However, the nonlinear optical absorptions of exfoliated TMDs are strongly limited by their nanoflakes morphology with uncontrollable lateral size and thickness. In this work, we provide an effective method to fully explore the nonlinear optical properties of MoSe2. Large-area and high quality lattice MoSe2 grown by chemical vapor deposition method was adopted as an optical modulator for the first time. The large-area MoSe2 shows excellent nonlinear optical absorption with a large modulation depth of 21.7% and small saturable intensity of 9.4 MW cm-2. After incorporating the MoSe2 optical modulator into fiber laser cavity as a saturable absorber, a highly stable Q-switching operation with single pulse energy of 224 nJ is achieved. The large-area MoSe2 possessing superior nonlinear optical properties compared to exfoliated nanoflakes affords possibility for the larger-area two-dimensional materials family as high performance optical devices.

  19. Controllable Growth of Monolayer MoS2 and MoSe2 Crystals Using Three-temperature-zone Furnace

    Science.gov (United States)

    Zheng, Binjie; Chen, Yuanfu

    2017-12-01

    Monolayer molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2) have attracted a great attention for their exceptional electronic and optoelectronic properties among the two dimensional family. However, controllable synthesis of monolayer crystals with high quality needs to be improved urgently. Here we demonstrate a chemical vapor deposition (CVD) growth of monolayer MoS2 and MoSe2 crystals using three-temperature-zone furnace. Systematical study of the effects of growth pressure, temperature and time on the thickness, morphology and grain size of crystals shows the good controllability. The photoluminescence (PL) characterizations indicate that the as-grown monolayer MoS2 and MoSe2 crystals possess excellent optical qualities with very small full-width-half-maximum (FWHM) of 96 me V and 57 me V, respectively. It is comparable to that of exfoliated monolayers and reveals their high crystal quality. It is promising that our strategy should be applicable for the growth of other transition metal dichalcogenides (TMDs) monolayer crystals.

  20. Facile fabrication of CNTs@C@MoSe2@Se hybrids with amorphous structure for high performance anode in lithium-ion batteries.

    Science.gov (United States)

    Jin, Rencheng; Cui, Yuming; Wang, Qingyao; Li, Guihua

    2017-12-15

    Amorphous MoSe 2 and Se anchored on amorphous carbon coated multiwalled carbon nanotubes (CNTs@C@MoSe 2 @Se) have been synthesized by a facile solvothermal strategy. The one dimensional CNTs@C@MoSe 2 @Se can effectively buffer the volume variation, prohibit the aggregation and facilitate electron and ion transport throughout the electrode. Furthermore, the combination of MoSe 2 and Se also provides buffer spaces for the volumetric change during cycling. Thus, the obtained CNTs@C@MoSe 2 @Se hybrids display the enhanced cycle stability and excellent high rate capacity. The reversible capacity of 1010mAhg -1 can be achieved after 100 cycles at the current density of 0.1Ag -1 . Even after 500 cycles, a reversible capacity of 508mAhg -1 is still retained at 5Ag -1 . Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Monolayer MoSe 2 Grown by Chemical Vapor Deposition for Fast Photodetection

    KAUST Repository

    Chang, Yung-Huang; Zhang, Wenjing; Zhu, Yihan; Han, Yu; Pu, Jiang; Chang, Jan-Kai; Hsu, Wei-Ting; Huang, Jing-Kai; Hsu, Chang-Lung; Chiu, Ming-Hui; Takenobu, Taishi; Li, Henan; Wu, Chih-I; Chang, Wen-Hao; Wee, Andrew Thye Shen; Li, Lain-Jong

    2014-01-01

    that the MoSe2 monolayer shows a much weaker bound exciton peak; hence, the phototransistor based on MoSe2 presents a much faster response time (<25 ms) than the corresponding 30 s for the CVD MoS2 monolayer at room temperature in ambient conditions

  2. Carrier transport dynamics in Mn-doped CdSe quantum dot sensitized solar cells

    Science.gov (United States)

    Poudyal, Uma; Maloney, Francis S.; Sapkota, Keshab; Wang, Wenyong

    2017-10-01

    In this work quantum dot sensitized solar cells (QDSSCs) were fabricated with CdSe and Mn-doped CdSe quantum dots (QDs) using the SILAR method. QDSSCs based on Mn-doped CdSe QDs exhibited improved incident photon-to-electron conversion efficiency. Carrier transport dynamics in the QDSSCs were studied using the intensity modulated photocurrent/photovoltage spectroscopy technique, from which transport and recombination time constants could be derived. Compared to CdSe QDSSCs, Mn-CdSe QDSSCs exhibited shorter transport time constant, longer recombination time constant, longer diffusion length, and higher charge collection efficiency. These observations suggested that Mn doping in CdSe QDs could benefit the performance of solar cells based on such nanostructures.

  3. Syntheses, structures, and magnetic properties of three new MnII-[MoIII(CN)7]4- molecular magnets.

    Science.gov (United States)

    Wei, Xiao-Qin; Pi, Qian; Shen, Fu-Xing; Shao, Dong; Wei, Hai-Yan; Wang, Xin-Yi

    2018-05-22

    By reaction of K4[MoIII(CN)7]·2H2O, Mn(ClO4)2·6H2O and bidentate chelating ligands, three new cyano-bridged compounds, namely Mn2(3-pypz)(H2O)(CH3CN)[Mo(CN)7] (1), Mn2(1-pypz)(H2O)(CH3CN)[Mo(CN)7] (2) and Mn2(pyim)(H2O)(CH3CN)[Mo(CN)7] (3) (3-pypz = 2-(1H-pyrazol-3-yl)pyridine, 1-pypz = 2-(1H-pyrazol-1-yl)pyridine, pyim = 2-(1H-imidazol-2-yl)pyridine), have been synthesized and characterized structurally and magnetically. Single crystal X-ray analyses revealed that although the chelating ligands are different, compounds 1 to 3 are isomorphous and crystallize in the same monoclinic space group C2/m. Connected by the bridging cyano groups, one crystallographically unique [Mo(CN)7]4- unit and three crystallographically unique MnII ions of different coordination environments form similar three-dimensional frameworks, which have a four-nodal 3,4,4,7-connecting topological net with a vertex symbol of {43}{44·62}2{410·611}. Magnetic measurements revealed that compounds 1-3 display long-range magnetic ordering with critical temperatures of 64, 66 and 62 K, respectively. These compounds are rare examples of a small number of chelating co-ligand coordinated [Mo(CN)7]4--based magnetic materials. Specifically, the bidentate chelating ligands were successfully introduced into the heptacyanomolybdate system for the first time.

  4. Oxygen isotope effect in 55Mn and 95Mo NMR spectra of the permanganate and molybdate ion

    International Nuclear Information System (INIS)

    Buckler, K.U.; Haase, A.R.; Lutz, O.; Mueller, M.; Nolle, A.

    1977-01-01

    By Fourier transform NMR spectroscopy the 55 Mn and 95 Mo resonance lines in the different permanganate and molybdate species Mn 16 Osub(4-n) 18 Osub(n) - and Mo 16 Osub(4-n) 18 Osub(n) 2- (n = 0,1,2,3,4) have been resolved in aqueous solutions of potassium permanganate and sodium molybdate. An isotopic effect on the Larmor frequency for 55 Mn of (0.59+-0.02)ppm and for 95 Mo of (0.25+-0.01)ppm to lower frequency has been found for the substitution of one 16 O atom by one 18 O atom. The relaxation rates 1/T 1 of 55 Mn in the different lines of the permanganate solution are equal within the limits of error. The oxygen exchange rate for the water-permanganate system has been evaluated. (orig.) [de

  5. High pressure effect on MoS2 and MoSe2 single crystals grown by ...

    Indian Academy of Sciences (India)

    Unknown

    tetrahedral anvil apparatus up to 5 GPa. In this paper we report room temperature resistance mea- surements as a function of pressure on MoS2 and MoSe2 single crystals. In each case the resistance decreases un- der pressure due to an increase in the carrier concentration. 2. Experimental. Single crystals of MoS2 and ...

  6. Lithium insertion in the two crystallographic forms of the binary-phase Mo15Se19

    Science.gov (United States)

    Tarascon, J. M.; Murphy, D. W.

    1986-02-01

    Compounds which can undergo topotactic insertion of lithium are of potential technological importance in secondary lithium batteries. In this paper we present the chemical and electrochemical insertion of lithium into the binary-phase Mo15Se19, which can exist in two crystallographic forms, denoted AA and BB, when prepared from In3Mo15Se19 and In2Mo15Se19, respectively. We show that both forms can reversibly accommodate up to eight lithium atoms, yielding two new series of compounds of formula LixMo15Se19. This behavior is consistent with the electronic structure of the host material predicted from band-structure calculations. The room-temperature phase diagram of both LixMo15Se19 systems as a function of x has been established using electrochemical test cells (based on Mo15Se19 as the cathode), and in situ x-ray measurements as the cells discharge. Both LixMo15Se19 systems contain three single-phase domains as a function of x: two hexagonal phases and an orthorhombic phase. The nature of the transitions between these single phases and the variation of the lattice parameters within a single-phase domain are reported. While the mechanism of intercalation of lithium is similar for both Mo15Se19 forms, there is a drastic difference in Li intercalation behavior for the parent indium phases In2Mo15Se19 and In3Mo15Se19. We found that In2Mo15Se19 can reversibly incorporate 6.4 lithium atoms while In3Mo15Se19 does not react. This behavior is explained on the basis of structural considerations.

  7. Three-Dimensional NiCo2O4@MnMoO4 Core-Shell Nanoarrays for High-Performance Asymmetric Supercapacitors.

    Science.gov (United States)

    Yuan, Yuliang; Wang, Weicheng; Yang, Jie; Tang, Haichao; Ye, Zhizhen; Zeng, Yujia; Lu, Jianguo

    2017-10-10

    Design of new materials with sophisticated nanostructure has been proven to be an efficient strategy to improve their properties in many applications. Herein, we demonstrate the successful combination of high electron conductive materials of NiCo 2 O 4 with high capacitance materials of MnMoO 4 by forming a core-shell nanostructure. The NiCo 2 O 4 @MnMoO 4 core-shell nanoarrays (CSNAs) electrode possesses high capacitance of 1169 F g -1 (4.24 F cm -2 ) at a current density of 2.5 mA cm -2 , obviously larger than the pristine NiCo 2 O 4 electrode. The asymmetric supercapacitors (ASCs), assembled with NiCo 2 O 4 @MnMoO 4 CSNAs as binder-free cathode and active carbon (AC) as anode, exhibit high energy density of 15 Wh kg -1 and high power density of 6734 W kg -1 . Cycle performance of NiCo 2 O 4 @MnMoO 4 CSNAs//AC ASCs, conducted at current density of 20 mA cm -2 , remain 96.45% of the initial capacitance after 10,000 cycles, demonstrating its excellent long-term cycle stability. Kinetically decoupled analysis reveals that the capacitive capacitance is dominant in the total capacitance of NiCo 2 O 4 @MnMoO 4 CSNAs electrode, which may be the reason for ultra long cycle stability of ASCs. Our assembled button ASC can easily light up a red LED for 30 min and a green LED for 10 min after being charged for 30 s. The remarkable electrochemical performance of NiCo 2 O 4 @MnMoO 4 CSNAs//AC ASCs is attributed to its enhanced surface area, abundant electroactive sites, facile electrolyte infiltration into the 3D NiCo 2 O 4 @MnMnO 4 nanoarrays and fast electron and ion transport path.

  8. Lithium insertion in the two crystallographic forms of the binary-phase Mo15Se19

    International Nuclear Information System (INIS)

    Tarascon, J.M.; Murphy, D.W.

    1986-01-01

    Compounds which can undergo topotactic insertion of lithium are of potential technological importance in secondary lithium batteries. In this paper we present the chemical and electrochemical insertion of lithium into the binary-phase Mo 15 Se 19 , which can exist in two crystallographic forms, denoted AA and BB, when prepared from In 3 Mo 15 Se 19 and In 2 Mo 15 Se 19 , respectively. We show that both forms can reversibly accommodate up to eight lithium atoms, yielding two new series of compounds of formula Li/sub x/Mo 15 Se 19 . This behavior is consistent with the electronic structure of the host material predicted from band-structure calculations. The room-temperature phase diagram of both Li/sub x/Mo 15 Se 19 systems as a function of x has been established using electrochemical test cells (based on Mo 15 Se 19 as the cathode), and in situ x-ray measurements as the cells discharge. Both Li/sub x/Mo 15 Se 19 systems contain three single-phase domains as a function of x: two hexagonal phases and an orthorhombic phase. The nature of the transitions between these single phases and the variation of the lattice parameters within a single-phase domain are reported. While the mechanism of intercalation of lithium is similar for both Mo 15 Se 19 forms, there is a drastic difference in Li intercalation behavior for the parent indium phases In''Mo 15 Se 19 and In 3 Mo 15 Se 19 . We found that In 2 Mo 15 Se 19 can reversibly incorporate 6.4 lithium atoms while In 3 Mo 15 Se 19 does not react. This behavior is explained on the basis of structural considerations

  9. Layer-by-layer thinning of MoSe{sub 2} by soft and reactive plasma etching

    Energy Technology Data Exchange (ETDEWEB)

    Sha, Yunfei [Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122 (China); Xiao, Shaoqing, E-mail: larring0078@hotmail.com [Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122 (China); Zhang, Xiumei [Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122 (China); Qin, Fang [Analysis & Testing Center, Jiangnan University, Wuxi 214122 (China); Gu, Xiaofeng, E-mail: xfgu@jiangnan.edu.cn [Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122 (China)

    2017-07-31

    Highlights: • Soft plasma etching technique using SF{sub 6} + N{sub 2} as precursors for layer-by-layer thinning of MoSe{sub 2} was adopted in this work. • Optical microscopy, Raman, photoluminescence and atomic force microscopy measurements were used to confirm the thickness change. • Layer-dependent vibrational and photoluminescence spectra of the etched MoSe{sub 2} were also demonstrated. • Equal numbers of MoSe{sub 2} layers can be removed uniformly without affecting the underlying SiO{sub 2} substrate and the remaining MoSe{sub 2} layers. - Abstract: Two-dimensional (2D) transition metal dichalcogenides (TMDs) like molybdenum diselenide (MoSe{sub 2}) have recently gained considerable interest since their properties are complementary to those of graphene. Unlike gapless graphene, the band structure of MoSe{sub 2} can be changed from the indirect band gap to the direct band gap when MoSe{sub 2} changed from bulk material to monolayer. This transition from multilayer to monolayer requires atomic-layer-precision thining of thick MoSe{sub 2} layers without damaging the remaining layers. Here, we present atomic-layer-precision thinning of MoSe{sub 2} nanaosheets down to monolayer by using SF{sub 6} + N{sub 2} plasmas, which has been demonstrated to be soft, selective and high-throughput. Optical microscopy, atomic force microscopy, Raman and photoluminescence spectra suggest that equal numbers of MoSe{sub 2} layers can be removed uniformly regardless of their initial thickness, without affecting the underlying SiO{sub 2} substrate and the remaining MoSe{sub 2} layers. By adjusting the etching rates we can achieve complete MoSe{sub 2} removal and any disired number of MoSe{sub 2} layers including monolayer. This soft plasma etching method is highly reliable and compatible with the semiconductor manufacturing processes, thereby holding great promise for various 2D materials and TMD-based devices.

  10. Gigantic spin splitting of exciton states in CdSe:Mn hexagonal crystal

    International Nuclear Information System (INIS)

    Komarov, A.V.; Ryabchenko, S.M.; Semenov, Yu.G.; Shanina, B.D.; Vitrikhovskij, N.I.; AN Ukrainskoj SSR, Kiev. Inst. Poluprovodnikov)

    1980-01-01

    Gigantic spin splitting of exciton states in magneto-doped semiconductors is observed for the first time in the CdSe: Mn hexagonal crystal. A theoretical interpretation of some features of the effect due to the anisotropy of the crystal is presented. The parameters of the band structure are determined by comparing with the experiments: Δ 1 =46+-3, Δ 2 =137+-1, Δ 3 =140.6+-0.3 meV. It is shown that in CdSe:Mn just as in cubic semiconductors, exchange interaction with magnetic impurities is ferromagnetic for electrons of the conductivity band and antiferromagnetic for electrons of the valence band. The exchange constants are of the same order of magnetude as those for the CdTe:Mn, ZnTe:Mn and ZnSe:Mn crystals

  11. Theoretical prediction of high electron mobility in multilayer MoS2 heterostructured with MoSe2

    Science.gov (United States)

    Ji, Liping; Shi, Juan; Zhang, Z. Y.; Wang, Jun; Zhang, Jiachi; Tao, Chunlan; Cao, Haining

    2018-01-01

    Two-dimensional (2D) MoS2 has been considered to be one of the most promising semiconducting materials with the potential to be used in novel nanoelectronic devices. High carrier mobility in the semiconductor is necessary to guarantee a low power dissipation and a high switch speed of the corresponding electronic device. Strain engineering in 2D materials acts as an important approach to tailor and design their electronic and carrier transport properties. In this work, strain is introduced to MoS2 through perpendicularly building van der Waals heterostructures MoSe2-MoS2. Our first-principles calculations demonstrate that acoustic-phonon-limited electron mobility can be significantly enhanced in the heterostructures compared with that in pure multilayer MoS2. It is found that the effective electron mass and the deformation potential constant are relatively smaller in the heterostructures, which is responsible for the enhancement in the electron mobility. Overall, the electron mobility in the heterostructures is about 1.5 times or more of that in pure multilayer MoS2 with the same number of layers for the studied structures. These results indicate that MoSe2 is an excellent material to be heterostructured with multilayer MoS2 to improve the charge transport property.

  12. Structural and magnetic properties of double-perovskite Ba2MnMoO6 by density functional theory

    International Nuclear Information System (INIS)

    Cardona, R.; Landinez Tellez, D.A.; Arbey Rodriguez M, J.; Fajardo, F.; Roa-Rojas, J.

    2008-01-01

    Perovskite-like materials which include magnetic elements have relevance due to the technological perspectives in the spintronics industry. In this work, we report the studies of Ba 2 MnMoO 6 material by using the density functional theory. The interchange-correlation potential was included through the generalized gradient approximation. Our structural calculations are in agreement with the experimental results which show that the material crystallizes in the 225 space group (Fm3-bar m) and has a lattice parameter of about 8070 A. The density of states study was carried out by considering the up and down spin orientations. Results show that Ba 2 MnMoO 6 has a conductor behavior due to dominant Mn spin-up and Mo spin-down contributions. The magnetic moment was calculated to be 2.9 μ B

  13. Structural evolution of dilute magnetic (Sn,Mn)Se films grown by molecular beam epitaxy

    Science.gov (United States)

    Kanzyuba, Vasily; Dong, Sining; Liu, Xinyu; Li, Xiang; Rouvimov, Sergei; Okuno, Hanako; Mariette, Henri; Zhang, Xueqiang; Ptasinska, Sylwia; Tracy, Brian D.; Smith, David J.; Dobrowolska, Margaret; Furdyna, Jacek K.

    2017-02-01

    We describe the structural evolution of dilute magnetic (Sn,Mn)Se films grown by molecular beam epitaxy on GaAs (111) substrates, as revealed by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. When the Mn concentration is increased, the lattice of the ternary (Sn,Mn)Se films evolves quasi-coherently from a SnSe2 two-dimensional (2D) crystal structure into a more complex quasi-2D lattice rearrangement, ultimately transforming into the magnetically concentrated antiferromagnetic MnSe 3D rock-salt structure as Mn approaches 50 at. % of this material. These structural transformations are expected to underlie the evolution of magnetic properties of this ternary system reported earlier in the literature.

  14. Electronic properties of mixed molybdenum dichalcogenide MoTeSe: LCAO calculations and Compton spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ahuja, Ushma [Department of Electrical Engineering, Veermata Jijabai Technological Institute, H. R. Mahajani Marg, Matunga (East), Mumbai 400019, Maharashtra (India); Kumar, Kishor; Joshi, Ritu [Department of Physics, University College of Science, M.L. Sukhadia University, Udaipur 313001, Rajasthan (India); Bhavsar, D.N. [Department of Physics, Bhavan' s Seth R.A. College of Science, Khanpur, Ahmedabad 380001, Gujarat (India); Heda, N.L., E-mail: nlheda@yahoo.co.in [Department of Pure and Applied Physics, University of Kota, Kota 324007, Rajasthan (India)

    2016-07-01

    We have employed linear combination of atomic orbitals (LCAO) method to compute the Mulliken’s population (MP), energy bands, density of states (DOS) and Compton profiles for hexagonal MoTeSe. The density functional theory (DFT) and hybridization of Hartree-Fock with DFT (B3LYP) have been used within the LCAO approximation. Performance of theoretical models has been tested by comparing the theoretical momentum densities with the experimental Compton profile of MoTeSe measured using {sup 137}Cs Compton spectrometer. It is seen that the B3LYP prescription gives a better agreement with the experimental data than other DFT based approximations. The energy bands and DOS depict an indirect band gap character in MoTeSe. In addition, a relative nature of bonding in MoTeSe and its isovalent MoTe{sub 2} is discussed in terms of equal-valence-electron-density (EVED) profiles. On the basis of EVED profiles it is seen that MoTeSe is more covalent than MoTe{sub 2}.

  15. Direct Magnetic Relief Recording Using As40S60: Mn-Se Nanocomposite Multilayer Structures.

    Science.gov (United States)

    Stronski, A; Achimova, E; Paiuk, O; Meshalkin, A; Prisacar, A; Triduh, G; Oleksenko, P; Lytvyn, P

    2017-12-01

    Processes of holographic recording of surface relief structures using As 2 S 3 :Mn-Se multilayer nanostructures as registering media were studied in this paper. Optical properties of As 2 S 3 :Mn, Se layers, and As 2 S 3 :Mn-Se multilayer nanostructures were investigated. Values of optical bandgaps were obtained from Tauc dependencies. Surface relief diffraction gratings were recorded. Direct one-stage formation of surface relief using multilayer nanostructures is considered. For the first time, possibility of direct formation of magnetic relief simultaneous with surface relief formation under optical recording using As 2 S 3 :Mn-Se multilayer nanostructures is shown.

  16. Effect of molecular intercalation on the local structure of superconducting Nax(NH3)yMoSe2 system

    Science.gov (United States)

    Simonelli, L.; Paris, E.; Wakita, T.; Marini, C.; Terashima, K.; Miao, X.; Olszewski, W.; Ramanan, N.; Heinis, D.; Kubozono, Y.; Yokoya, T.; Saini, N. L.

    2017-12-01

    We have studied the local structure of layered Nax(NH3)yMoSe2 system by Mo K-edge extended X-ray absorption fine structure (EXAFS) measurements performed as a function of temperature. We find that molecular intercalation in MoSe2 largely affects the Mo-Se network while Mo-Mo seems to sustain small changes. The Einstein temperature (ΘE) of Mo-Mo distance hardly changes (∼264 K) indicating that bond strength of this distance remains unaffected by intercalation. On the other hand, Mo-Se distance suffers a softening, revealed by the decrease of ΘE from ∼364 K to ∼350 K. The results indicate that Na+ ion transported by NH3 molecules may enter between the two MoSe-layers resulting reduced Se-Se coupling. Therefore, increased hybridization between Se 4p and Mo 4d orbitals due to inter-layer disorder is the likely reason of metallicity in intercalated MoSe2 and superconductivity at low temperature.

  17. Reaction mechanisms of MnMoO{sub 4} for high capacity anode material of Li secondary battery

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung-Soo; Ogura, Seiichiro; Ikuta, Hiromasa; Uchimoto, Yoshiharu; Wakihara, Masataka [Department of Applied Chemistry, Tokyo Institute of Techonology, 2-12-1, Ookayama, Tokyo 152-8552 Meguro (Japan)

    2002-02-02

    Crystalline MnMoO{sub 4} was synthesized using a conventional solid reaction method and investigated for its physical and electrochemical properties as an anode material for Li secondary battery. The reversible amount of Li insertion/removal of MnMoO{sub 4} anode during the first cycle was about 800 mA h/g, accompanied by irreversible structural transformation into amorphous material. The amorphization during the first Li insertion was investigated by structural analysis using XRD of electrode. The charge compensation during Li insertion/removal was examined by measurement of X-ray Absorption Near Edge Structure (XANES) spectroscopy. Despite its irreversible structural transformation to amorphous during the first lithiation, subsequent cycles showed a reasonable cyclability. This paper presents the electrochemical properties of MnMoO{sub 4} and discusses the mechanism underlying the Li insertion/removal process.

  18. Effect of microstructure on the cleavage fracture strength of low carbon Mn-Ni-Mo bainitic steels

    International Nuclear Information System (INIS)

    Im, Young-Roc; Lee, Byeong-Joo; Oh, Yong Jun; Hong, Jun Hwa; Lee, Hu-Chul

    2004-01-01

    The effects of the microstructure on the cleavage fracture strength of low carbon Mn-Ni-Mo bainitic steels were examined. A four-point bend test and double-notched bend specimens were used to measure the cleavage fracture strength of the alloys and identify the cleavage initiating micro-cracks, respectively. The cleavage fracture strength and DBTT of Mn-Ni-Mo bainitic steels were strongly affected by the alloy carbon content. The decrease in the alloy carbon content resulted in a decrease in the inter-lath cementite-crowded layers and higher cleavage fracture strength. Micro-cracks that formed across the inter-lath cementite-crowded layers were observed to initiate cleavage fracture. The width of these inter-lath cementite-crowded layers was accepted as a cleavage initiating micro-crack size in the micro-mechanical modeling of the cleavage fracture, and the measured cleavage strength values of the bainitic Mn-Ni-Mo steels were well represented by the modified Griffith relationship

  19. Few-layered MoSe2 nanosheets as an advanced electrode material for supercapacitors.

    Science.gov (United States)

    Balasingam, Suresh Kannan; Lee, Jae Sung; Jun, Yongseok

    2015-09-21

    We report the synthesis of few-layered MoSe2 nanosheets using a facile hydrothermal method and their electrochemical charge storage behavior. A systematic study of the structure and morphology of the as-synthesized MoSe2 nanosheets was performed. The downward peak shift in the Raman spectrum and the high-resolution transmission electron microscopy images confirmed the formation of few-layered nanosheets. The electrochemical energy-storage behavior of MoSe2 nanosheets was also investigated for supercapacitor applications in a symmetric cell configuration. The MoSe2 nanosheet electrode exhibited a maximum specific capacitance of 198.9 F g(-1) and the symmetric device showed 49.7 F g(-1) at a scan rate of 2 mV s(-1). A capacitance retention of approximately 75% was observed even after 10 000 cycles at a high charge-discharge current density of 5 A g(-1). The two-dimensional MoSe2 nanosheets exhibited a high specific capacitance and good cyclic stability, which makes it a promising electrode material for supercapacitor applications.

  20. Large-area snow-like MoSe2 monolayers: synthesis, growth mechanism, and efficient electrocatalyst application.

    Science.gov (United States)

    Huang, Jingwen; Liu, Huiqiang; Jin, Bo; Liu, Min; Zhang, Qingchun; Luo, Liqiong; Chu, Shijin; Chu, Sheng; Peng, Rufang

    2017-07-07

    This study explores the large-area synthesis of controllable morphology, uniform, and high-quality monolayer. MoSe 2 is essential for its potential application in optoelectronics, photocatalysis, and renewable energy sources. In this study, we successfully synthesized snow-like MoSe 2 monolayers using a simple chemical vapor deposition method. Results reveal that snow-like MoSe 2 is a single crystal with a hexagonal structure, a thickness of ∼0.9 nm, and a lateral dimension of up to 20 μm. The peak position of the photoluminescence spectra is ∼1.52 eV corresponding to MoSe 2 monolayer. The growth mechanism of the snow-like MoSe 2 monolayer was investigated and comprised a four-step process during growth. Finally, we demonstrate that the snow-like MoSe 2 monolayers are ideal electrocatalysts for hydrogen evolution reactions (HERs), reflected by a low Tafel slope of ∼68 mV/decade. Compared with the triangular-shaped MoSe 2 monolayer, the hexangular snow-like shape with plentiful edges is superior for perfect electrocatalysts for HERs or transmission devices of optoelectronic signals.

  1. The Structure and Mechanical Properties of Ni-Mo PM Steels with Addition of Mn And Cu

    Science.gov (United States)

    Lichańska, E.; Kulecki, P.; Pańcikiewicz, K.

    2017-12-01

    The aim of the study was to evaluate the effect of chemical composition on the structure and mechanical properties of Mn-Ni-Mo and Ni-Mo-Cu PM steels. Pre-alloyed powder Astaloy 85Mo, diffusion alloyed powders Distaloy AQ and Distaloy AB produced by Höganäs, low carbon ferromanganese, carbonyl nickel powder T255 with three-dimensional filamentary structure and graphite CU-F have been used as the basic powders. Three mixtures with compositions of Fe-1%Mn-(0.5/1.75)%Ni-(0.5/0.85)%Mo-0.8%C and Fe-1.75%Ni-0.5%Mo-1.5%Cu-0.8%C were prepared in a Turbula mixer. Green compacts were single pressed in a steel die at 660 MPa according to PN-EN ISO 2740 standard. Sinterhardening was carried out at 1250°C in a mixture of 95% N2+5% H2 for 60 minutes. Mechanical tests (tensile, bend, hardness) and microstructural investigations were performed. Additionally, XRD and EDS analysis, fractographic investigations were carried out. The microstructures of steels investigated were mainly bainitic or bainitic-martensitic. Addition 1% Mn to Distaloy AQ based steel caused increase of tensile properties (YS from 422 to 489 MPa, UTS from 522 to 638 MPa, TRS from 901 to 1096 MPa) and decrease of plasticity (elongation from 3.65 to 2.84%).

  2. Structure, tribological and electrochemical properties of low friction TiAlSiCN/MoSeC coatings

    International Nuclear Information System (INIS)

    Bondarev, A.V.; Kiryukhantsev-Korneev, Ph.V.; Sheveyko, A.N.; Shtansky, D.V.

    2015-01-01

    Highlights: • TiAlSiCN/MoSeC coatings for tribological applications. • Doping with MoSeC reduces friction coefficient in humid air from 0.8–0.9 to 0.05. • Doping with MoSeC increases wear resistance by one-two orders of magnitude. • TiAlSiCN/MoSeC coatings demonstrated low friction coefficient in distilled water. • TiAlSiCN/MoSeC coatings showed superior tribological properties at moderate temperatures. - Abstract: The present paper is focused on the development of hard tribological coatings with low friction coefficient (CoF) in different environments (humid air, distilled water) and at elevated temperatures. TiAlSiCN/MoSeC coatings were deposited by magnetron sputtering of four-segment targets consisting of quarter circle TiAlSiCN segments, obtained by self-propagating high-temperature synthesis, and one or two cold pressed segments made of MoSe 2 and C powders in a ratio 1:1 wt%. The structure and phase composition of coatings were investigated by means of X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The coatings were characterized in terms of their hardness, elastic modulus, and elastic recovery. The tribological properties of coatings were investigated first at room temperature against Al 2 O 3 and WC–Co balls, after which studied in distilled water and during continuous heating in air in the temperature range of 25–400 °C against Al 2 O 3 counterpart material. To evaluate their electrochemical characteristics, the coatings were tested in 1 N H 2 SO 4 solution. The obtained results show that the coating hardness depends on the amount of MoSeC additives and decreased from 40 to 28 (one MoSeC segment) and 12 GPa (two MoSeC segments). Doping with MoSeC resulted in a significant reduction of CoF values measured in humid air (RH 60 ± 5%) from 0.8–0.9 to 0.05 and an increase of wear resistance by one or two orders of magnitude depending on counterpart material. This was attributed

  3. Structure, tribological and electrochemical properties of low friction TiAlSiCN/MoSeC coatings

    Energy Technology Data Exchange (ETDEWEB)

    Bondarev, A.V.; Kiryukhantsev-Korneev, Ph.V.; Sheveyko, A.N.; Shtansky, D.V., E-mail: shtansky@shs.misis.ru

    2015-02-01

    Highlights: • TiAlSiCN/MoSeC coatings for tribological applications. • Doping with MoSeC reduces friction coefficient in humid air from 0.8–0.9 to 0.05. • Doping with MoSeC increases wear resistance by one-two orders of magnitude. • TiAlSiCN/MoSeC coatings demonstrated low friction coefficient in distilled water. • TiAlSiCN/MoSeC coatings showed superior tribological properties at moderate temperatures. - Abstract: The present paper is focused on the development of hard tribological coatings with low friction coefficient (CoF) in different environments (humid air, distilled water) and at elevated temperatures. TiAlSiCN/MoSeC coatings were deposited by magnetron sputtering of four-segment targets consisting of quarter circle TiAlSiCN segments, obtained by self-propagating high-temperature synthesis, and one or two cold pressed segments made of MoSe{sub 2} and C powders in a ratio 1:1 wt%. The structure and phase composition of coatings were investigated by means of X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The coatings were characterized in terms of their hardness, elastic modulus, and elastic recovery. The tribological properties of coatings were investigated first at room temperature against Al{sub 2}O{sub 3} and WC–Co balls, after which studied in distilled water and during continuous heating in air in the temperature range of 25–400 °C against Al{sub 2}O{sub 3} counterpart material. To evaluate their electrochemical characteristics, the coatings were tested in 1 N H{sub 2}SO{sub 4} solution. The obtained results show that the coating hardness depends on the amount of MoSeC additives and decreased from 40 to 28 (one MoSeC segment) and 12 GPa (two MoSeC segments). Doping with MoSeC resulted in a significant reduction of CoF values measured in humid air (RH 60 ± 5%) from 0.8–0.9 to 0.05 and an increase of wear resistance by one or two orders of magnitude depending on

  4. High-spin configuration of Mn in Bi{sub 2}Se{sub 3} three-dimensional topological insulator

    Energy Technology Data Exchange (ETDEWEB)

    Wolos, Agnieszka, E-mail: agnieszka.wolos@fuw.edu.pl [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw (Poland); Drabinska, Aneta [Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw (Poland); Borysiuk, Jolanta [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw (Poland); Sobczak, Kamil [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Kaminska, Maria [Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw (Poland); Hruban, Andrzej [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Institute of Electronic Materials Technology, ul. Wolczynska 133, 01-919 Warsaw (Poland); Strzelecka, Stanislawa G.; Materna, Andrzej; Piersa, Miroslaw; Romaniec, Magdalena; Diduszko, Ryszard [Institute of Electronic Materials Technology, ul. Wolczynska 133, 01-919 Warsaw (Poland)

    2016-12-01

    Electron paramagnetic resonance was used to investigate Mn impurity in Bi{sub 2}Se{sub 3} topological insulator grown by the vertical Bridgman method. Mn in high-spin S=5/2, Mn{sup 2+}, configuration was detected regardless of the conductivity type of the host material. This means that Mn{sup 2+}(d{sup 5}) energy level is located within the valence band, and Mn{sup 1+}(d{sup 6}) energy level is outside the energy gap of Bi{sub 2}Se{sub 3}. The electron paramagnetic resonance spectrum of Mn{sup 2+} in Bi{sub 2}Se{sub 3} is characterized by the isotropic g-factor |g|=1.91 and large axial parameter D=−4.20 GHz h. This corresponds to the zero-field splitting of the Kramers doublets equal to 8.4 GHz h and 16.8 GHz h, respectively, which is comparable to the Zeeman splitting for the X-band. Mn in Bi{sub 2}Se{sub 3} acts as an acceptor, effectively reducing native-high electron concentration, compensating selenium vacancies, and resulting in p-type conductivity. However, Mn-doping simultaneously favors formation of native donor defects, most probably selenium vacancies. For high Mn-doping it may lead to the resultant n-type conductivity related with strong non-stoichiometry and degradation of the crystal structure - switching from Bi{sub 2}Se{sub 3} to BiSe phase. - Highlights: • We studied electron paramagnetic resonance in Bi{sub 2}Se{sub 3}:Mn. • We found Mn in high-spin Mn{sup 2+} configuration in both n-type and p-type samples. • The g-factor for Mn{sup 2+} equals to 1.91 and axial parameter D=−4.20 GHz h. • Mn acts as an acceptor. • Mn substitution affects formation of native donors.

  5. Magnetic Fe2MO4 (M:Fe, Mn) activated carbons: Fabrication, characterization and heterogeneous Fenton oxidation of methyl orange

    International Nuclear Information System (INIS)

    Nguyen, Thi Dung; Phan, Ngoc Hoa; Do, Manh Huy; Ngo, Kim Tham

    2011-01-01

    We present a simple and efficient method for the fabrication of magnetic Fe 2 MO 4 (M:Fe and Mn) activated carbons (Fe 2 MO 4 /AC-H, M:Fe and Mn) by impregnating the activated carbon with simultaneous magnetic precursor and carbon modifying agent followed by calcination. The obtained samples were characterized by nitrogen adsorption isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM), and the catalytic activity in heterogeneous Fenton oxidation of methyl orange (MO) was evaluated. The resulting Fe 2 MnO 4 /AC-H showed higher catalytic activity in the methyl orange oxidation than Fe 3 O 4 /AC-H. The effect of operational parameters (pH, catalyst loading H 2 O 2 dosage and initial MO concentration) on degradation performance of the oxidation process was investigated. Stability and reusability of selected catalyst were also tested.

  6. Concentrations of Se, Ba, Zn and Mn in Brazil nuts

    Energy Technology Data Exchange (ETDEWEB)

    Armelin, Maria José A.; Maihara, Vera A.; Cardoso, Paulo S.; Saiki, Mitiko [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Cozollino, Silvia M.F., E-mail: marmelin@ipen.br, E-mail: vmaihara@ipen.br, E-mail: msaiki@ipen.br, E-mail: pscsilva@ipen.br, E-mail: smfcozzo@usp.br [Universidade de São Paulo (USP), SP (Brazil). Faculdade de Ciências Farmacêuticas

    2017-07-01

    The concentrations of Se, Ba, Zn and Mn were determined in samples of Brazil nuts collected in two ways: a) in a production farm predominantly for export and, b) in various points of sale from different regions of Brazil. Instrumental neutron activation analysis was the analytical technique used in this study. Results indicate that the concentrations of Se and Ba varied greatly among the Brazil nut samples analyzed. This large variability may be related to the soil characteristics from which the nuts were produced. An inverse correlation was observed between the concentrations of Se and Ba. On the other hand, the concentrations of Zn and Mn did not show significant differences among these samples. (author)

  7. Concentrations of Se, Ba, Zn and Mn in Brazil nuts

    International Nuclear Information System (INIS)

    Armelin, Maria José A.; Maihara, Vera A.; Cardoso, Paulo S.; Saiki, Mitiko; Cozollino, Silvia M.F.

    2017-01-01

    The concentrations of Se, Ba, Zn and Mn were determined in samples of Brazil nuts collected in two ways: a) in a production farm predominantly for export and, b) in various points of sale from different regions of Brazil. Instrumental neutron activation analysis was the analytical technique used in this study. Results indicate that the concentrations of Se and Ba varied greatly among the Brazil nut samples analyzed. This large variability may be related to the soil characteristics from which the nuts were produced. An inverse correlation was observed between the concentrations of Se and Ba. On the other hand, the concentrations of Zn and Mn did not show significant differences among these samples. (author)

  8. Mechanism and kinetics of Fe, Cr, Mo and Mn atom interaction with molecular oxygen

    International Nuclear Information System (INIS)

    Akhmadov, U.S.; Zaslonko, I.S.; Smirnov, V.N.

    1988-01-01

    Rate constants of atomic interaction of some transition metals (Fe, Cr, Mo, Mn) with molecular oxygen are measured in shock waves using the resonance atomic-absorption method. A new method for determination of the parameter γ in the modified Lambert-Beer law D=ε(lN)γ is suggested and applied. Bond strength in CrO and MoO molecules is estimated

  9. Photoemission study on the formation of Mo contacts to CuInSe2

    International Nuclear Information System (INIS)

    Nelson, A.J.; Niles, D.W.; Kazmerski, L.L.; Rioux, D.; Patel, R.; Hoechst, H.

    1992-01-01

    Synchrotron radiation soft-x-ray photoemission spectroscopy was used to investigate the development of the electronic structure at the Mo/CuInSe 2 interface. Mo overlayers were e-beam deposited in steps on single-crystal n-type CuInSe 2 at ambient temperature. Photoemission measurements were acquired after each growth in order to observe changes in the valence-band electronic structure as well as changes in the In 4d, Se 3d, and Mo 4d core lines. Photoemission measurements on the valence-band and core lines were also obtained after annealing. The results were used to correlate the interface chemistry with the electronic structure at this interface and to directly determine the maximum possible Schottky barrier height φ b to be ≤0.2 eV at the Mo/CuInSe 2 junction before annealing, thus showing that this contact is essentially ohmic

  10. Electronic structure investigation of MoS2 and MoSe2 using angle-resolved photoemission spectroscopy and ab initio band structure studies.

    Science.gov (United States)

    Mahatha, S K; Patel, K D; Menon, Krishnakumar S R

    2012-11-28

    Angle-resolved photoemission spectroscopy (ARPES) and ab initio band structure calculations have been used to study the detailed valence band structure of molybdenite, MoS(2) and MoSe(2). The experimental band structure obtained from ARPES has been found to be in good agreement with the theoretical calculations performed using the linear augmented plane wave (LAPW) method. In going from MoS(2) to MoSe(2), the dispersion of the valence bands decreases along both k(parallel) and k(perpendicular), revealing the increased two-dimensional character which is attributed to the increasing interlayer distance or c/a ratio in these compounds. The width of the valence band and the band gap are also found to decrease, whereas the valence band maxima shift towards the higher binding energy from MoS(2) to MoSe(2).

  11. Preparation of 2D MoSe2/PEDOT:PSS composite and its thermoelectric properties

    Science.gov (United States)

    Li, Xia; Liu, Congcong; Wang, Tongzhou; Wang, Wenfang; Wang, Xiaodong; Jiang, Qinglin; Jiang, Fengxing; Xu, Jingkun

    2017-11-01

    Nowadays, inorganic/polymer composites have attracted significant interest in thermoelectric field, since the composite materials usually achieve their respective advantages complementary to each other. In this work, molybdenum diselenide (MoSe2) was synthesized by a facile hydrothermal method. Solution processible two-dimensional (2D) MoSe2 nanosheets (NSs) were successfully obtained using dimethylsulfoxide (DMSO) solvent or lithium intercalation procedure. Combined with Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), MoSe2/PEDOT:PSS composite thin films were fabricated by direct vacuum-filtration method. Thermoelectric properties of composite thin films were investigated systematically and found that 2D MoSe2 NSs and PEDOT:PSS have the synergistic effect on improving thermoelectric properties. The maximum power factor was calculated to be 48.6 µW m-1 K-2 with 5 wt% 2D MoSe2 NSs embedding into PEDOT:PSS matrix, which is almost 69% higher than that of pure PEDOT:PSS. These results demonstrate that 2D inorganic/polymer composite method is one of promising strategies to get high-performance polymer-based thermoelectric composites.

  12. Nanocrystalline Mn-Mo-Ce Oxide Anode Doped Rare Earth Ce and Its Selective Electro-catalytic Performance

    Directory of Open Access Journals (Sweden)

    SHI Yan-hua

    2017-09-01

    Full Text Available The anode oxide of nanocrystalline Mn-Mo-Ce was prepared by anode electro-deposition technology, and its nanostructure and selective electro-catalytic performance were investigated using the SEM, EDS, XRD, HRTEM, electrochemical technology and oxygen evolution efficiency testing. Furthermore, the selective electro-catalytic mechanism of oxygen evolution and chlorine depression was discussed. The results show that the mesh-like nanostructure Mn-Mo-Ce oxide anode with little cerium doped is obtained, and the oxygen evolution efficiency for the anode in the seawater is 99.51%, which means a high efficiency for the selective electro-catalytic for the oxygen evolution. Due to the structural characteristics of γ-MnO2, the OH- ion is preferentially absorbed, while Cl- absorption is depressed. OH- accomplishes the oxygen evolution process during the valence transition electrocatalysis of Mn4+/Mn3+, completing the selective electro-catalysis process. Ce doping greatly increases the reaction activity, and promotes the absorption and discharge; the rising interplanar spacing between active (100 crystalline plane promotes OH- motion and the escape of newborn O2, so that the selective electro-catalytic property with high efficient oxygen evolution and chlorine depression is achieved from the nano morphology effect.

  13. Post-GOE redox insights from Mo isotopes, Ce anomalies, and Mn from the 2.24 Ga Kazput Formation

    Science.gov (United States)

    Thoby, M.; Konhauser, K.; Philippot, P.; Killingsworth, B.; Warchola, T.; Lalonde, S.

    2017-12-01

    Following the Great Oxidation event (GOE) defined from 2.45 to 2.2 Ga, an event marking the first appearance of widespread atmospheric oxygen, a combination of decreased Mn(II) supply from land and increased Mn(IV)-precipitation in the oceans should have resulted in lower concentrations of Mn in seawater. Nevertheless, it appears that some early Proterozoic marine sediments record high seawater Mn concentrations hundreds of millions of years after the GOE. Here we investigate a Mn excursion associated with marine carbonates and shales of the 2.31 Ga Kazput Formation. Samples were recovered from drill core collected during the Turee Creek Drilling Project (TCDP). Using molybdenum (Mo) isotope data coupled with cerium (Ce) anomalies, we define the redox condition of the Kazput depositional environment. Initial results show no Mo fractionation and few cerium anomalies in carbonates, pointing to an anoxic basin without Mn oxide precipitates. Additionally, XRF data on the shales indicates an association of Mn with calcium (Ca) suggesting an anoxic environment at the time of their deposition. Our results provide new insights into the nature and environment of the Turee Creek basin and the extent of oxygenation of surface waters after the GOE.

  14. Thermal transport properties of MoS 2 and MoSe 2 monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Kandemir, Ali; Yapicioglu, Haluk; Kinaci, Alper; Çağın, Tahir; Sevik, Cem

    2016-01-11

    Isolation of single to few layer transition metal dichalgogenides open alternate venues in application of 2 dimensional materials to nanoelectronics. Either for general overheating issues or specific application in thermoelectric devices, the characterization of the thermal transport in these new low dimensional materials is needed for their efficient implementation. In this study, lattice thermal conductivities of single layer MoS2 and MoSe2 are evaluated using classical molecular dynamics method. The interactions between atoms are defined by Stillinger-Weber type empirical potentials that are developed to represent structural, mechanical, and vibrational properties of the given materials. In parameterization of the potentials, a stochastic optimization algorithm, namely particle swarm optimization is utilized. The final parameter sets produce quite consistent results with DFT in terms of lattice parameters, bond distances, elastic constants and vibrational properties of both single layer MoS2 and MoSe2. The predicted thermal properties of both materials are in very good agreement with earlier first principles calculations. The discrepancies between calculations and experimental measurements are most likely to be caused by pristine nature of the structures in our simulations.

  15. Dynamical control of Mn spin-system cooling by photogenerated carriers in a (Zn,Mn)Se/BeTe heterostructure

    Science.gov (United States)

    Debus, J.; Maksimov, A. A.; Dunker, D.; Yakovlev, D. R.; Tartakovskii, I. I.; Waag, A.; Bayer, M.

    2010-08-01

    The magnetization dynamics of the Mn spin system in an undoped (Zn,Mn)Se/BeTe type-II quantum well was studied by a time-resolved pump-probe photoluminescence technique. The Mn spin temperature was evaluated from the giant Zeeman shift of the exciton line in an external magnetic field of 3 T. The relaxation dynamics of the Mn spin temperature to the equilibrium temperature of the phonon bath after the pump-laser-pulse heating can be accelerated by the presence of free electrons. These electrons, generated by a control laser pulse, mediate the spin and energy transfer from the Mn spin system to the lattice and bypass the relatively slow direct spin-lattice relaxation of the Mn ions.

  16. Synthesis and characterization of manganese diselenide nanoparticles (MnSeNPs): Determination of capsaicin by using MnSeNP-modified glassy carbon electrode.

    Science.gov (United States)

    Sukanya, Ramaraj; Sakthivel, Mani; Chen, Shen-Ming; Chen, Tse-Wei; Al-Hemaid, Fahad M A; Ajmal Ali, M; Elshikh, Mohamed Soliman

    2018-06-02

    A new type of manganese diselenide nanoparticles (MnSeNPs) was synthesized by using a hydrothermal method. Their surface morphology, crystallinity and elemental distribution were characterized by using transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy which scrutinize the formation of the NPs. The NPs were coated on a glassy carbon electrode (GCE), and electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry were applied to study the electroanalytical properties towards the oxidation of the food additive capsaicin. The modified GCE displays lower charge transfer resistance (R ct  = 29.52 Ω), a larger active surface area (0.089 cm 2 /g, and more efficient electrochemical oxidation of capsaicin compared to a MnS 2 /GCE and a bare GCE. The oxidation peak potential is 0.43 V (vs. Ag/AgCl) which is lower than that of previously reported GCEs. The sensor has a detection limit as low as 0.05 μM and an electrochemical sensitivity of 2.41 μA μM -1  cm -2 . The method was applied to the determination of capsaicin in pepper samples. Graphical abstract Electrochemical determination of capsaicin in pepper extract by using MnSeNPs modified electrode.

  17. Magnetic Fe{sub 2}MO{sub 4} (M:Fe, Mn) activated carbons: Fabrication, characterization and heterogeneous Fenton oxidation of methyl orange

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thi Dung [Institute of Chemical Technology, Vietnamese Academy of Science and Technology, 01 Mac Dinh Chi, District 1, Ho Chi Minh (Viet Nam); Phan, Ngoc Hoa [Department of Chemical Technology, Hochiminh University of Technology, 268 Ly Thuong Kiet, District 10, Ho Chi Minh (Viet Nam); Do, Manh Huy, E-mail: huydoma@vast-hcm.ac.vn [Institute of Chemical Technology, Vietnamese Academy of Science and Technology, 01 Mac Dinh Chi, District 1, Ho Chi Minh (Viet Nam); Ngo, Kim Tham [Institute of Chemical Technology, Vietnamese Academy of Science and Technology, 01 Mac Dinh Chi, District 1, Ho Chi Minh (Viet Nam); College of science, Can Tho University, 3/2, Can Tho (Viet Nam)

    2011-01-30

    We present a simple and efficient method for the fabrication of magnetic Fe{sub 2}MO{sub 4} (M:Fe and Mn) activated carbons (Fe{sub 2}MO{sub 4}/AC-H, M:Fe and Mn) by impregnating the activated carbon with simultaneous magnetic precursor and carbon modifying agent followed by calcination. The obtained samples were characterized by nitrogen adsorption isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM), and the catalytic activity in heterogeneous Fenton oxidation of methyl orange (MO) was evaluated. The resulting Fe{sub 2}MnO{sub 4}/AC-H showed higher catalytic activity in the methyl orange oxidation than Fe{sub 3}O{sub 4}/AC-H. The effect of operational parameters (pH, catalyst loading H{sub 2}O{sub 2} dosage and initial MO concentration) on degradation performance of the oxidation process was investigated. Stability and reusability of selected catalyst were also tested.

  18. ¿Y, cómo se hacen?

    Directory of Open Access Journals (Sweden)

    Juan Ruiz

    2015-01-01

    Full Text Available El mundo de los dibujos animados es producto de la imaginación, de la fantasía que vuela en los sueños de los hombres de cualquier edad. El artículo relata la forma en cómo estos simpáticos personajes, que vemos a diario en el cine o la televisión, pueden moverse tan libremente y con tanto desenfado. Se parte de la idea o argumento, el guionista narra la historia de lo que será el animado. Luego el director con un dibujante trazan las escenas principales de la historia (storyboard o guión dibujado se discute con los artistas y realizadores del filme; una vez aprobado este se perfila el diseño de los personajes, se realiza la escenografía (maquetas de ser necesario. Se hacen los parlamentos o diálogos de los personajes para que actores(as pongan las voces y sigue el proceso más fino y técnico.

  19. MnFe2O4/CdSe magneto-fluorescent nanocomposite for possible biomedical applications

    Science.gov (United States)

    Chandunika, R. K.; Vijayaraghavan, R.; Sahu, Niroj Kumar

    2018-04-01

    Acombined superparamagnetic and fluorescent MnFe2O4/CdSe multifunctional nanocompositehas been prepared by suitable surface functionalizationswith citric acid, polyethyleneimine(PEI) and thioglycolic acid (ThA).and the samples were characterized by XRD, FT-IR, TEM, Zeta Potential, VSM, UV-Vis and PL spectroscopy. MnFe2O4 crystalizes with average size of 38.6 nm whereas CdSe with average size of 2.03 nm. In composite, the CdSe quantum dots (QD) are homogeneously distributed in the matrix of porous MnFe2O4 nanoparticles. Thenanocomposites are well dispersed in aqueous solvent and possess significant magnetic and luminescence properties which may be utilised for magnetic resonance imaging and luminescence tagging of biomolecules.

  20. One-pot synthesis of stable water soluble Mn:ZnSe/ZnS core/shell quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Hao; Gao Xue; Liu Siyu; Su Xingguang, E-mail: suxg@jlu.edu.cn [College of Chemistry, Jilin University, Department of Analytical Chemistry (China)

    2013-06-15

    In this paper, Mn:ZnSe/ZnS core/shell-doped quantum dots (d-dots) with 3-mercaptopropionic acid as the stabilizer are successfully synthesized through a simple one-pot synthesis procedure in aqueous solution. The average diameter of Mn:ZnSe/ZnS core/shell d-dots is about 2.9 nm, which is lager than that of Mn:ZnSe cores (about 1.9 nm). The optical features and structure of the obtained Mn:ZnSe/ZnS core/shell quantum dots have been characterized by UV-Vis and fluorescence spectroscopy, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The photostability against UV irradiation and chemical stability against H{sub 2}O{sub 2} etching have been studied, and the results showed that the prepared Mn:ZnSe/ZnS core/shell d-dots are more stable than CdTe quantum dots prepared in aqueous solution. Finally, the resulting core/shell quantum dots are used as fluorescent label in human osteoblast-like HepG2 cell imaging.

  1. Electric field modulation of Schottky barrier height in graphene/MoSe2 van der Waals heterointerface

    International Nuclear Information System (INIS)

    Sata, Yohta; Moriya, Rai; Morikawa, Sei; Yabuki, Naoto; Masubuchi, Satoru; Machida, Tomoki

    2015-01-01

    We demonstrate a vertical field-effect transistor based on a graphene/MoSe 2 van der Waals (vdW) heterostructure. The vdW interface between the graphene and MoSe 2 exhibits a Schottky barrier with an ideality factor of around 1.3, suggesting a high-quality interface. Owing to the low density of states in graphene, the position of the Fermi level in the graphene can be strongly modulated by an external electric field. Therefore, the Schottky barrier height at the graphene/MoSe 2 vdW interface is also modulated. We demonstrate a large current ON-OFF ratio of 10 5 . These results point to the potential high performance of the graphene/MoSe 2 vdW heterostructure for electronics applications

  2. Construction of Hierarchical CNT/rGO-Supported MnMoO4 Nanosheets on Ni Foam for High-Performance Aqueous Hybrid Supercapacitors.

    Science.gov (United States)

    Mu, Xuemei; Du, Jingwei; Zhang, Yaxiong; Liang, Zhilin; Wang, Huan; Huang, Baoyu; Zhou, Jinyuan; Pan, Xiaojun; Zhang, Zhenxing; Xie, Erqing

    2017-10-18

    Rationally designed conductive hierarchical nanostructures are highly desirable for supporting pseudocapacitive materials to achieve high-performance electrodes for supercapacitors. Herein, manganese molybdate nanosheets were hydrothermally grown with graphene oxide (GO) on three-dimensional nickel foam-supported carbon nanotube structures. Under the optimal graphene oxide concentration, the obtained carbon nanotubes/reduced graphene oxide/MnMoO 4 composites (CNT/rGO/MnMoO 4 ) as binder-free supercapacitor cathodes perform with a high specific capacitance of 2374.9 F g -1 at the scan rate of 2 mV s -1 and good long-term stability (97.1% of the initial specific capacitance can be maintained after 3000 charge/discharge cycles). The asymmetric device with CNT/rGO/MnMoO 4 as the cathode electrode and the carbon nanotubes/activated carbon on nickel foam (CNT-AC) as the anode electrode can deliver an energy density of 59.4 Wh kg -1 at the power density of 1367.9 W kg -1 . These superior performances can be attributed to the synergistic effects from each component of the composite electrodes: highly pseudocapacitive MnMoO 4 nanosheets and three-dimensional conductive Ni foam/CNTs/rGO networks. These results suggest that the fabricated asymmetric supercapacitor can be a promising candidate for energy storage devices.

  3. Synthesis and magnetic properties of layered MnPSxSe3-x (0 < x < 3) and corresponding intercalation compounds of 2,2'-bipyridine

    International Nuclear Information System (INIS)

    Yan, Xiaobing; Chen, Xingguo; Qin, Jingui

    2011-01-01

    Graphical abstract: A series of new layered MnPS x Se 3-x (0 x Se 3-x exhibited antiferromagnetism similar to MnPS 3 or MnPSe 3 , but the intercalation of 2,2'-bipyridine can dramatically change the properties of MnPS x Se 3-x slab. Research highlights: → A series of new MnPS x Se 3-x are designed and synthesized for the first time and their layered structure has been determined. → The intercalation chemistry has been initially studied via the intercalation of 2,2'-bipyridine with MnPS x Se 3-x . → The magnetic properties of the series MnPS x Se 3-x and the corresponding intercalation compounds of 2,2'-bipydine have been studied. And the relationship between the structure and the magnetic propertied has been primarily explored. -- Abstract: In this work, we synthesize a series of new MnPS x Se 3-x (0 1-y PS x Se 3-x (bipy) 4y , x = 1.2, 1.8 and 2.4) via the intercalation of 2,2'-bipyridine with MnPS x Se 3-x . XRD results confirm that MnPS x Se 3-x compounds show the layered structure and can be regarded as the solid solution of MnPS 3 and MnPSe 3 . Magnetic measurements indicate that MnPS x Se 3-x compounds exhibit paramagnetism with negative Weiss constant in the paramagnetic temperature region, and an antiferromagnetic phase transition occurs at the Neel temperature. It is found that the magnetic properties of MnPS x Se 3-x slab are dramatically changed after the intercalation of 2,2'-bipyridine, which is close related to the relative ratio of S and Se atom as well as the intralayered Mn 2+ vacancies of MnPS x Se 3-x slab.

  4. Electric field modulation of Schottky barrier height in graphene/MoSe2 van der Waals heterointerface

    OpenAIRE

    Sata, Yohta; Moriya, Rai; Morikawa, Sei; Yabuki, Naoto; Masubuchi, Satoru; Machida, Tomoki

    2015-01-01

    We demonstrate a vertical field-effect transistor based on a graphene/MoSe2 van der Waals (vdW) heterostructure. The vdW interface between the graphene and MoSe2 exhibits a Schottky barrier with an ideality factor of around 1.3, suggesting a high-quality interface. Owing to the low density of states in graphene, the position of the Fermi level in the graphene can be strongly modulated by an external electric field. Therefore, the Schottky barrier height at the graphene/MoSe2 vdW interface is ...

  5. Thermoelectric response of bulk and monolayer MoSe2 and WSe2

    KAUST Repository

    Sarath Kumar, S. R.

    2015-02-24

    We study the thermoelectric properties of bulk and monolayer MoSe2 and WSe2 by first-principles calculations and semiclassical Boltzmann transport theory. The lattice thermal conductivity is calculated using the self-consistent iterative approach as well as the single-mode relaxation time approximation. The acoustical and optical contributions to the lattice thermal conductivity are evaluated along with the influence of the phonon mean free path. The employed methodology enables a quantitative comparison of the thermoelectric properties of transition-metal dichalcogenides. In particular, WSe2 is found to be superior to MoSe2 for thermoelectric applications.

  6. Thermoelectric response of bulk and monolayer MoSe2 and WSe2

    KAUST Repository

    Sarath Kumar, S. R.; Schwingenschlö gl, Udo

    2015-01-01

    We study the thermoelectric properties of bulk and monolayer MoSe2 and WSe2 by first-principles calculations and semiclassical Boltzmann transport theory. The lattice thermal conductivity is calculated using the self-consistent iterative approach as well as the single-mode relaxation time approximation. The acoustical and optical contributions to the lattice thermal conductivity are evaluated along with the influence of the phonon mean free path. The employed methodology enables a quantitative comparison of the thermoelectric properties of transition-metal dichalcogenides. In particular, WSe2 is found to be superior to MoSe2 for thermoelectric applications.

  7. Rocking disc electro-deposition of copper films on Mo/MoSe{sub 2} substrates

    Energy Technology Data Exchange (ETDEWEB)

    Cummings, Charles Y.; Frith, Paul E. [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Zoppi, Guillaume; Forbes, Ian [Northumbria Photovoltaics Applications Centre, Northumbria University, NE1 8ST (United Kingdom); Rogers, Keith D. [Cranfield Health, Cranfield University, Shrivenham Campus, Swindon, SN6 8LA (United Kingdom); Lane, David W. [Department of Applied Science, Security and Resilience, Cranfield University, Shrivenham, Swindon, SN6 8LA (United Kingdom); Marken, Frank, E-mail: F.Marken@bath.ac.uk [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom)

    2011-08-31

    A novel electro-deposition method based on a rocking disc system with {pi}/3 amplitude and variable frequency is introduced. Uniform copper films were deposited from a 0.1 M CuSO{sub 4}/3.0 M NaOH/0.2 M sorbitol bath directly onto 12.1 cm{sup 2} Mo/MoSe{sub 2} substrates with X-ray diffraction showing a thickness variation of {+-}5% over this area. Investigation of the mass transport conditions suggests (i) uniform diffusion over the sample, (ii) a rate of mass transport proportional to the square root of the rocking rate, and (iii) turbulent conditions, which are able to dislodge gas bubbles during electro-deposition.

  8. Enhanced magnetoresistance and Griffiths phase induced by Mo substitution in La0.7Ca0.15Sr0.15Mn1-xMoxO3 (0 ≤ x ≤ 0.05)

    International Nuclear Information System (INIS)

    Narsinga Rao, G; Chen, J W; Neeleshwar, S; Chen, Y Y; Wu, M K

    2009-01-01

    Structural, magnetic and electrical properties of the La 0.7 Ca 0.15 Sr 0.15 Mn 1-x Mo x O 3 (0 ≤ x ≤ 0.05) compounds have been investigated. Powder x-ray analysis reveals that the sample with x = 0 crystallizes in the rhombohedral (R 3-bar c) structure, whereas in the Mo doped samples the structure can be indexed by an orthorhombic (Pbnm) structure. The important observations of the magnetic and transport properties are: (i) the Mo substitution induces a distinct suppression of the metal-insulator (T MI ) and ferromagnetic (FM)-paramagnetic transition (T C ) and the temperature of T MI was found to be higher than T C in the Mo-doped samples, (ii) the substitution of Mo enhances the magnetoresistance at room temperature, (iii) a large deviation from the Curie-Weiss law well above T C in the Mo substituted samples indicates the existence of a Griffiths phase and (iv) long-range FM order persists in all samples with a linear decrease of saturation moment as x increases. These results are discussed in terms of the Mn-site disorder and opening of strong FM coupling between Mn 2+ -O-Mn 3+ , due to the Mn 2+ ions induced by Mo 6+ at the expense of Mn 4+ ions in the La 0.7 Ca 0.15 Sr 0.15 Mn 1-x Mo x O 3 system.

  9. Photoluminescence Enhancement and Structure Repairing of Monolayer MoSe 2 by Hydrohalic Acid Treatment

    KAUST Repository

    Han, Hau-Vei

    2015-12-30

    Atomically thin two-dimensional transition-metal dichalcogenides (TMDCs) have attracted much attention recently due to their unique electronic and optical properties for future optoelectronic devices. The chemical vapor deposition (CVD) method is able to generate TMDCs layers with a scalable size and a controllable thickness. However, the TMDC monolayers grown by CVD may incorporate structural defects, and it is fundamentally important to understand the relation between photoluminescence and structural defects. In this report, point defects (Se vacancies) and oxidized Se defects in CVD-grown MoSe2 monolayers are identified by transmission electron microscopy and X-ray photoelectron spectroscopy. These defects can significantly trap free charge carriers and localize excitons, leading to the smearing of free band-to-band exciton emission. Here, we report that the simple hydrohalic acid treatment (such as HBr) is able to efficiently suppress the trap-state emission and promote the neutral exciton and trion emission in defective MoSe2 monolayers through the p-doping process, where the overall photoluminescence intensity at room temperature can be enhanced by a factor of 30. We show that HBr treatment is able to activate distinctive trion and free exciton emissions even from highly defective MoSe2 layers. Our results suggest that the HBr treatment not only reduces the n-doping in MoSe2 but also reduces the structural defects. The results provide further insights of the control and tailoring the exciton emission from CVD-grown monolayer TMDCs.

  10. Detection of DNA via the fluorescence quenching of Mn-doped ZnSe D-dots/doxorubicin/DNA ternary complexes system.

    Science.gov (United States)

    Gao, Xue; Niu, Lu; Su, Xingguang

    2012-01-01

    This manuscript reports a method for the detection of double-stranded DNA, based on Mn:ZnSe d-dots and intercalating agent doxorubicin (DOX). DOX can quench the photoluminescence (PL) of Mn:ZnSe d-dots through photoinduced electron transfer process, after binding with Mn:ZnSe d-dots. The addition of DNA can result in the formation of the Mn:ZnSe d-dots-DOX-DNA ternary complexes, the fluorescence of the Mn:ZnSe d-dots-DOX complexes would be further quenched by the addition of DNA, thus allowing the detection of DNA. The formation mechanism of the Mn:ZnSe d-dots-DOX-DNA ternary complexes was studied in detail in this paper. Under optimal conditions, the quenched fluorescence intensity of Mn:ZnSe d-dots-DOX system are perfectly described by Stern-Volmer equation with the concentration of hsDNA ranging from 0.006 μg mL(-1) to 6.4 μg mL(-1). The detection limit (S/N = 3) for hsDNA is 0.5 ng mL(-1). The proposed method was successfully applied to the detection of DNA in synthetic samples and the results were satisfactory.

  11. Dual-Native Vacancy Activated Basal Plane and Conductivity of MoSe2 with High-Efficiency Hydrogen Evolution Reaction.

    Science.gov (United States)

    Gao, Daqiang; Xia, Baorui; Wang, Yanyan; Xiao, Wen; Xi, Pinxian; Xue, Desheng; Ding, Jun

    2018-04-01

    Although transition metal dichalcogenide MoSe 2 is recognized as one of the low-cost and efficient electrocatalysts for the hydrogen evolution reaction (HER), its thermodynamically stable basal plane and semiconducting property still hamper the electrocatalytic activity. Here, it is demonstrated that the basal plane and edges of 2H-MoSe 2 toward HER can be activated by introducing dual-native vacancy. The first-principle calculations indicate that both the Se and Mo vacancies together activate the electrocatalytic sites in the basal plane and edges of MoSe 2 with the optimal hydrogen adsorption free energy (ΔG H* ) of 0 eV. Experimentally, 2D MoSe 2 nanosheet arrays with a large amount of dual-native vacancies are fabricated as a catalytic working electrode, which possesses an overpotential of 126 mV at a current density of 100 mV cm -2 , a Tafel slope of 38 mV dec -1 , and an excellent long-term durability. The findings pave a rational pathway to trigger the activity of inert MoSe 2 toward HER and also can be extended to other layered dichalcogenide. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. LaMn1-xFe xO3 and LaMn0.1-xFe0.90Mo x O3 perovskites: synthesis, characterization and catalytic activity in H2O2 reactions

    Directory of Open Access Journals (Sweden)

    Fabiano Magalhães

    2008-09-01

    Full Text Available In this work two perovskites were prepared: LaMn1-xFe xO3, and LaMn0.1-x Fe0.90Mo xO3. XRD and Mössbauer spectroscopy suggest the formation of pure phase perovskite with the incorporation of Fe and Mo in the structure. The catalytic activity of these materials was studied in two reactions with H2O2: the decomposition to O2, and the oxidation of the model organic contaminant methylene blue. The perovskite composition strongly affects the catalytic activity, while Fe decreases the H2O2 decomposition Mo strongly improves dye oxidation.

  13. Photoluminescence of ZnBeMnSe solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Strzałkowski, K., E-mail: skaroll@fizyka.umk.pl; Firszt, F.; Marasek, A.

    2017-04-15

    In this paper optical properties of Zn{sub 1-x-y}Be{sub x}Mn{sub y}Se mixed semiconductors were studied as a function of both, temperature and excitation power. The crystals under investigation were grown by the high-pressure, high-temperature vertical Bridgman technique within the range of the composition 0.05≤x, y≤0.2. Photoluminescence spectra for the lowest content of Mn and Be exhibit character typical for II-VI semiconductors together with intensive yellow-orange manganese emission. Evolution of the excitonic emission as the function of temperature allowed determining the energy gap of the investigated semiconductors. Absorbance and photoluminescence excitation spectra confirmed crystal field splitting of excited atomic terms of manganese ions into the states, denoted according to the crystal field theory in the case of tetrahedral symmetry. Temperature and laser power dependences of luminescence showed anomalous behavior of the manganese emission. It turned out that the position of the Mn{sup 2+} related luminescence band does not change monotonically with the variation of the temperature or the excitation power. Finally, switching of the manganese emission has been observed. By increasing laser power of exciting radiation, the Mn-related emission could be quenched by almost two orders in magnitude. This effect was especially strong at low temperature and it was fully reversible.

  14. Optical and structural properties of natural MnSeO{sub 4} mineral thin film

    Energy Technology Data Exchange (ETDEWEB)

    Kariper, Ishak Afsin, E-mail: akariper@gmail.com [Erciyes University, Education Faculty, Kayseri (Turkey)

    2017-05-15

    Manganese selenite (MnSeO{sub 4}) crystalline thin film has been produced with chemical bath deposition on substrates (commercial glass). Properties of the thin film, such as transmittance, absorption, and optical band gap and refraction index have been investigated via UV/VIS Spectrum. The structural properties of orthorhombic form have been observed in XRD. The structural and optical properties of MnSeO{sub 4} thin films, deposited at different pH levels were analyzed. Some properties of the films have been changed with the change of pH level, which has been deeply investigated. The grain size of MnSeO{sub 4} thin film has reached its highest value at pH 9. The refraction index and extinction coefficient of MnSeO{sub 4} thin films were measured to be 1.53, 2.86, 2.07, 1.53 (refraction index) and 0.005, 0.029, 0.014, 0.005 (extinction coefficient) for grain sizes 21, 13, 26, and 5 nm respectively. The band gaps (Eg) of the films were measured to be 2.06, 2.57, 2.04, and 2.76 eV for the grain sizes mentioned above. The value of dielectric constant at pH 10 was calculated as 1.575. (author)

  15. High spin state driven magnetism and thermoelectricity in Mn doped topological insulator Bi2Se3

    Science.gov (United States)

    Maurya, V. K.; Dong, C. L.; Chen, C. L.; Asokan, K.; Patnaik, S.

    2018-06-01

    We report on the synthesis, and structural - magnetic characterizations of Mn doped Bi2Se3 towards achieving a magnetically doped topological insulator. High quality single crystals of MnxBi2-xSe3 (x = 0, 0.03, 0.05, 0.1) are grown and analysed by X-ray diffraction (XRD), Low Energy Electron Diffraction (LEED), Scanning electron microscopy (SEM), and X-ray absorption near-edge structure spectroscopy (XANES). Magnetic properties of these samples under ZFC-FC protocol and isothermal magnetization confirm ferromagnetic correlation above x = 0.03 value. XANES measurements confirm that the dopant Mn is in Mn2+ state. This is further reconfirmed to be in high spin state by fitting magnetic data with Brillouin function for J = 5/2. Both Hall and Seebeck measurements indicate a sign change of charge carriers above x = 0.03 value of Mn doping. We propose Mn doped Bi2Se3 to be a potential candidate for electromagnetic and thermoelectric device applications involving topological surface states.

  16. Synthesis and X-ray examination of ternary molybdates, KAIn(MoO4)3 (A - Mg, Mn)

    International Nuclear Information System (INIS)

    Smirnyagina, N.N.; Khazheeva, Z.I.; Kozhevnikova, N.M.; Alekseev, F.P.; Mokhosoev, M.V.

    1985-01-01

    The interaction in ternary salt systems K 2 MoO 4 -AMoO 4 -In 2 (MoO 4 ) 3 is studied in the 200-1000 deg temperature range. The triangulation is performed. The formation of new ternary molybdates of the KAIn(MoO 4 ) 3 composition is established. They are investigated with the methods of differential thermal analysis and roentgenography. It is found that KMgIn(MoO 4 ) 3 and KMnIn(MoO 4 ) 3 compounds are isostructural and crystallize in monoclinic crystal system. Elementary cell parameters for KMgIn((MoO 4 ) 3 are a=9.753(7); b=9.282(6); c=13.583(9) A; β=94.1(1) deg; for KMnIn(MoO 4 ) 3 - a=9.80(2); b=9.28(1); c=13.64(2) A; β=94.7(1) A; cells of such dimensions contain four formula units of the above composition. Crystal densities calculated for KMgIn(MoO 4 ) 3 and KMnIn(MnO 4 ) 3 are 3.56 and 3.69 g/cm 3 , respectively

  17. The Role of Anionogenic Elements (As, Sb, Mo, Se, S, P, N, Cl, F, C) In The Formation of Technogenic Geochemical Anomalies

    Science.gov (United States)

    Abrosimova, Natalya; Bortnikova, Svetlana

    2017-12-01

    The study was conducted on the example of sulphide-containing mine tailings with a varying amount of sulphide and arsenide minerals, from three distinct tailings dumps situated in Russia: Karabash Mine Site, South Ural; Komsomolsk tailings impoundment, Kemerovo region; Khovu-Aksy mine site, Tuva Republic. The aim of the study was to compare the mobility of anionogenic elements (As, Sb, Mo, Se, S, P, N, Cl, F, C) and their role in migration, precipitation, and concentration of metals during the water-tailings interaction depending on the physicochemical parameters (pH, Eh) of the medium and the mineral composition of the waste material. Using slightly acidic leaching experiments the quantitative estimation of mobile forms of elements is given. Based on the compositions of the obtained water leaching solutions, aqueous speciation of chemical elements and saturation index of key minerals in the experimental solutions were calculated. The results of calculating forms of chemical elements made it possible to construct series of mobility of metals and metalloids in solutions with different physicochemical parameters. In the alkaline conditions, Sb>As>Cd>Cu>Zn>Fe>Pb, when the medium is acidified, the series changes, As>Cd>Cu>Zn>Pb>Sb>Fe in weakly alkaline conditions, Sb>Mn>As>Zn>Fe however, when the medium is acidified, the series changes to Cd>Mn>Pb>Cu>Zn>Sb>Ni>Fe>As under acidic conditions Cd>Cu>Zn>Pb>Mn>Fe>Se>Mo>Sb>As>Ni. The mineral composition of the tailings was investigated, which will allow to determine the sources of toxic elements and to understand the processes of secondary mineral formation in technogenic objects. Arsenopyrite and pyrite predominate in the heavy fraction of the Komsomolsk tailings impoundment, arsenopyrite grains are often corroded, Sb contained in Sb oxide and Sb sulfide. The pyrite and barite are determined in the solid matter of the Karabash Mine Site and chalcopyrite, sphalerite, tennantite Cu3AsS3, and tetrahedrite (Cu,Fe)12Sb4S13 are

  18. Explorations of new phases in the Ga(III)/In(III)-Mo(VI)-Se(IV)/Te(IV)-O systems.

    Science.gov (United States)

    Kong, Fang; Hu, Chun-Li; Hu, Ting; Zhou, Yong; Mao, Jiang-Gao

    2009-07-07

    Systematic explorations of new phases in the Ga(III)/In(III)-Mo(VI)-Se(IV)/Te(IV)-O systems by hydrothermal syntheses or solid-state reactions at high-temperature led to four new quaternary compounds, namely, Ga(2)MoQ(2)O(10) (Q = Se, Te), In(2)Mo(2)Se(2)O(13)(H(2)O) and In(2)MoTe(2)O(10). Ga(2)MoQ(2)O(10) (Q = Se, Te) are isostructural and their structures feature a 3D network of gallium selenite/tellurite with 12-member ring tunnels along b-axis, the distorted MoO(6) octahedra are attached on the wall of the above tunnels. The structure of In(2)Mo(2)Se(2)O(13)(H(2)O) features a new pillared-layered architecture composed of 2D indium(III) selenite layers that are interconnected by Mo(2)O(10) dimers, forming 8-membered ring tunnels along the b-axis. The structure of In(2)MoTe(2)O(10) features a 2D indium oxide layer formed by corner- and edge-sharing InO(6) and InO(7) polyhedra with MoO(4) tetrahedra and TeO(n) (n = 4, 5) polyhedra hanging on both sides of the layer, there are weak interlayer Te-O bonds of 2.512 A. Results of optical diffuse reflectance spectrum measurements indicate that all four compounds are insulators, which are in agreement with results of band structure calculations based on DFT methods.

  19. Structural and magnetic characterization of martensitic Ni-Mn-Ga thin films deposited on Mo foil

    International Nuclear Information System (INIS)

    Chernenko, V.A.; Anton, R. Lopez; Kohl, M.; Barandiaran, J.M.; Ohtsuka, M.; Orue, I.; Besseghini, S.

    2006-01-01

    Three martensitic Ni 51.4 Mn 28.3 Ga 20.3 thin films sputter-deposited on a Mo foil were investigated with regard to their crystal and magnetic domain structures, as well as their magnetic and magnetostrain properties. The film thicknesses, d, were 0.1, 0.4 and 1.0μm. X-ray and electron diffraction patterns revealed a tetragonal modulated martensitic phase (10M) in the films. The surface topography and micromagnetic structure were studied by scanning probe microscopy. A maze magnetic domain structure featuring a large out-of-plane magnetization component was found in all films. The domain width, δ, depends on the film thickness as δ∼d. The thickness dependencies of the saturation magnetization, saturation magnetic field and magnetic anisotropy were clarified. Beam cantilever tests on the Ni-Mn-Ga/Mo composite as a function of magnetic field showed reversible strains, which are larger than ordinary magnetostriction

  20. Chevrel-phase solid solution Mo 6Se 8- xTe x. Study of its superconducting, magnetic and NMR properties

    Science.gov (United States)

    Hamard1a, C.; Auffret, V.; Peña, O.; Le Floch, M.; Nowak, B.; Wojakowski, A.

    2000-09-01

    The Chevrel-phase solid solution Mo 6Se 8-Mo 6Te 8 was studied by X-ray diffraction, AC and DC magnetic susceptibility and 77Se and 125Te NMR spectroscopy. From the smooth evolution of the lattice parameters and superconducting critical temperatures, a progressive substitution of selenium atoms by tellurium is shown, on the whole range of composition 0⩽ x⩽8, in the formulation Mo 6Se 8- xTe x: the unit-cell volume increases linearly because of the larger ionic size of tellurium, while Tc decreases rapidly (from 6.45 down to 0 K) because of the different formal oxidation states of the anions and a probable evolution of the Fermi level in the density of states. Results of magnetic susceptibility support this model and suggest the inhibition of the intrinsic metallic behavior with increasing x. The NMR spectra of the binaries Mo 6Se 8 and Mo 6Te 8 reveal two significant features, attributed to two different chalcogen positions in the R 3¯ symmetry. At low Se contents in Mo 6Se 8- xTe x ( x=7.5, 7 and 6), selenium first fills the two X(2) sites along the three-fold axis (2c positions), and then it becomes statistically distributed over the general 6f positions, leading to broad 77Se NMR lines. On the other hand, substitution of Te atoms in Mo 6Se 8 seems to occur in a random way, creating large perturbations on the 125Te NMR spectra, over the whole range of x. Theoretical analysis based on the presence of two anisotropic lines (of axial and non-axial symmetries, respectively) allowed us to estimate their anisotropy factors and to perfectly simulate the frequency response of both Mo 6Se 8 and Mo 6Te 8 binaries. Analysis of the Knight shift anisotropy leads us to conclude about the importance of the molybdenum z 2 molecular orbital contribution which controls the Mo-X dipolar interactions.

  1. Measurement of the Single Top Quark Production Cross Section and <mo stretchy='false'>|mo>Vtb stretchy='false'>|mo> in Events with One Charged Lepton, Large Missing Transverse Energy, and Jets at CDF

    Energy Technology Data Exchange (ETDEWEB)

    Aaltonen, T.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Butti, P.; Buzatu, A.; Calamba, A.; Camarda, S.; Campanelli, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Cho, K.; Chokheli, D.; Clark, A.; Clarke, C.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Cremonesi, M.; Cruz, D.; Cuevas, J.; Culbertson, R.; d’Ascenzo, N.; Datta, M.; de Barbaro, P.; Demortier, L.; Deninno, M.; D’Errico, M.; Devoto, F.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; Donati, S.; D’Onofrio, M.; Dorigo, M.; Driutti, A.; Ebina, K.; Edgar, R.; Elagin, A.; Erbacher, R.; Errede, S.; Esham, B.; Farrington, S.; Fernández Ramos, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Franklin, M.; Freeman, J. C.; Frisch, H.; Funakoshi, Y.; Galloni, C.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González López, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gramellini, E.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, M.; Harr, R. F.; Harrington-Taber, T.; Hatakeyama, K.; Hays, C.; Heinrich, J.; Herndon, M.; Hirschbuehl, D.; Hocker, A.; Hong, Z.; Hopkins, W.; Hou, S.; Hughes, R. E.; Husemann, U.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kambeitz, M.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. H.; Kim, S. B.; Kim, Y. J.; Kim, Y. K.; Kimura, N.; Kirby, M.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Kruse, M.; Kuhr, T.; Kurata, M.; Laasanen, A. T.; Lammel, S.; Lancaster, M.; Lannon, K.; Latino, G.; Lee, H. S.; Lee, J. S.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lipeles, E.; Lister, A.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lucà, A.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Marchese, L.; Margaroli, F.; Marino, P.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Moon, C. S.; Moore, R.; Morello, M. J.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Nigmanov, T.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagliarone, C.; Palencia, E.; Palni, P.; Papadimitriou, V.; Parker, W.; Pauletta, G.; Paulini, M.; Paus, C.; Phillips, T. J.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Pranko, A.; Prokoshin, F.; Ptohos, F.; Punzi, G.; Redondo Fernández, I.; Renton, P.; Rescigno, M.; Rimondi, F.; Ristori, L.; Robson, A.; Rodriguez, T.; Rolli, S.; Ronzani, M.; Roser, R.; Rosner, J. L.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Sakumoto, W. K.; Sakurai, Y.; Santi, L.; Sato, K.; Saveliev, V.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, E. E.; Schwarz, T.; Scodellaro, L.; Scuri, F.; Seidel, S.; Seiya, Y.; Semenov, A.; Sforza, F.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.; Shreyber-Tecker, I.; Simonenko, A.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Song, H.; Sorin, V.; St. Denis, R.; Stancari, M.; Stentz, D.; Strologas, J.; Sudo, Y.; Sukhanov, A.; Suslov, I.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng, P. K.; Thom, J.; Thomson, E.; Thukral, V.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Trovato, M.; Ukegawa, F.; Uozumi, S.; Vázquez, F.; Velev, G.; Vellidis, C.; Vernieri, C.; Vidal, M.; Vilar, R.; Vizán, J.; Vogel, M.; Volpi, G.; Wagner, P.; Wallny, R.; Wang, S. M.; Waters, D.; Wester, W. C.; Whiteson, D.; Wicklund, A. B.; Wilbur, S.; Williams, H. H.; Wilson, J. S.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, H.; Wright, T.; Wu, X.; Wu, Z.; Yamamoto, K.; Yamato, D.; Yang, T.; Yang, U. K.; Yang, Y. C.; Yao, W. -M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Zanetti, A. M.; Zeng, Y.; Zhou, C.; Zucchelli, S.

    2014-12-31

    We report a measurement of single top quark production in proton-antiproton collisions at a center-of-mass energy of smo>=>1.96mn> TeV using a data set corresponding to mn>7.5mn> fbmo>->1mn> of integrated luminosity collected by the Collider Detector at Fermilab. We select events consistent with the single top quark decay process tmo stretchy="false">→mo>Wb stretchy="false">→mo>>νb by requiring the presence of an electron or muon, a large imbalance of transverse momentum indicating the presence of a neutrino, and two or three jets including at least one originating from a bottom quark. An artificial neural network is used to discriminate the signal from backgrounds. We measure a single top quark production cross section of mn>3.0mn>>4mn>->0.53mn>+>0.57mn> pb and set a lower limit on the magnitude of the coupling between the top quark and bottom quark mo stretchy="false">|mo

  2. Hydrothermal synthesis of 3D hierarchical flower-like MoSe{sub 2} microspheres and their adsorption performances for methyl orange

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Hua, E-mail: tanghua@mail.ujs.edu.cn; Huang, Hong; Wang, Xiaoshuai; Wu, Kongqiang; Tang, Guogang; Li, Changsheng

    2016-08-30

    Highlights: • 3D hierarchical flower-like MoSe{sub 2} microspheres have been fabricated via a hydrothermal method. • A possible evolution process of 3D hierarchical flower-like MoSe{sub 2} microspheres was discussed. • Flower-like MoSe{sub 2} microspheres exhibit excellent adsorption properties for dye methyl orange removal from aqueous solution. - Abstract: In this paper, we report a facile and versatile modified hydrothermal method for synthesis of three-dimensional (3D) hierarchical flower-like MoSe{sub 2} microspheres using selenium powders and sodium molybdate as raw materials. The as-prepared MoSe{sub 2} was investigated for application as an adsorbent for the removal of dye contaminants from water. Power X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS) and N{sub 2} adsorption-desorption analysis were carried out to study the microstructure of the as-synthesized product. A possible growth mechanism of MoSe{sub 2} flower-like microspheres was preliminarily proposed on the basis of observation of a time-dependent morphology evolution process. Moreover, the MoSe{sub 2} sample exhibited good adsorption properties, with maximum adsorption capacity of 36.91 mg/g for methyl orange. The adsorption process of methyl orange on 3D hierarchical flower-like MoSe{sub 2} microspheres was systematically investigated, which was found to obey the pseudo-second-order rate equation and Langmuir adsorption model.

  3. Combining sedimentological, trace metal (Mn, Mo) and molecular evidence for reconstructing past water-column redox conditions: The example of meromictic Lake Cadagno (Swiss Alps)

    DEFF Research Database (Denmark)

    Wirth, S. B.; Gilli, A.; Niemann, H.

    2013-01-01

    reducing conditions and subsequent rapid precipitation of Mn-(oxyhydr) oxide minerals during episodic and short-term water-column mixing events mainly due to flood-induced underflows. At 9800 +/- 130 cal yr BP, a rapid transition to fully sulfidic conditions is indicated by the marked enrichment of Mo......-transition period beginning shortly after the lake formation similar to 12.5 kyr ago. The oxic period is characterized by low sedimentary Mn and Mo concentrations, as well as by the absence of any remnants of anoxygenic phototrophic sulfur bacteria. Enhanced accumulation/preservation of Mn (up to 5.6 wt...

  4. Solid solution limits and selected mechanical properties of the quaternary L12 trialuminide Al-Ti-Mn-Mo

    International Nuclear Information System (INIS)

    Schneibel, J.H.

    1994-01-01

    Intermetallics based on the trialuminide Al 3 Ti, or on Al 11 Ti 5 , have been extensively researched in recent years. Alloying with approximately 10 at.% of first-row transition elements, such as Cr or Mn, converts the DO 22 structure of Al 3 Ti to L1 2 . Although this transition to the L1 2 structure increases the number of independent slip systems to five and causes substantial softening, room-temperature tensile ductilities and fracture toughnesses remain low. Typical values for the room-temperature ductilities of Al-25Ti-8Cr and Al-25Ti-9Mn are 0.2% and room-temperature fracture toughnesses of trialuminides range from 2 to 5 MPa m 1/2 . Reasons for the low fracture toughness of trialuminides have been discussed by Turner et al. and George et al. On a phenomenological basis, it appears that fracture toughnesses might improve, if either Poisson's ratio or the ratio of the bulk and shear moduli can be increased. In principle, this might be achieved by macroalloying ternary L1 2 trialuminides, while at the same time maintaining the L1 2 crystal structure. Focusing on first-row transition elements, Kumar and Brown investigated a range of such quaternary compounds. They did not observe any improvement in ductility, as compared to the ternary compounds. In the present work, it was decided to focus on a second-row transition element, namely, 2 molybdenum. As compared to Cr and Mn, which are only slightly soluble in Al 3 Ti, up to 20 at. % Mo dissolves in Al 3 Ti at 1,198 K. This raises the question whether substantial amounts of Mo also dissolve in the cubic ternary trialuminides such as Al-Ti-Mn. In order to verify this possibility, the extent of the single-phase region of cubic Al-Ti-Mn-Mo intermetallic was mapped out at 1,473 K. In addition, a limited characterization of room-temperature mechanical properties was carried out

  5. Suppression of antiferromagnetic interactions through Cu vacancies in Mn-substituted CuInSe2 chalcopyrites

    International Nuclear Information System (INIS)

    Yao Jinlei; Brunetta, Carl D; Aitken, Jennifer A

    2012-01-01

    Stoichiometric and Cu-poor Cu 0.95-x Mn 0.05 InSe 2 (x = 0-0.20) compounds were synthesized by high-temperature, solid-state reactions. The presence of copper vacancies is revealed by Rietveld refinements of combined neutron and x-ray powder diffraction data. The antiferromagnetic interaction is depressed by the copper deficiency, which may be explained as the competition between the antiferromagnetic Mn-Se-eMn superexchange interaction and the hole-mediated ferromagnetic exchange induced by the copper vacancy. The introduction of copper vacancies is proposed to be a viable route to impart carrier-mediated ferromagnetic exchange in the chalcopyrite-based dilute magnetic semiconductors. (paper)

  6. Acoustoelastic evaluation of the 20 MnMoNi 55 structural material of the pressure vessels of Angra 2 and 3 nuclear reactors

    International Nuclear Information System (INIS)

    Dutra, Marco Aurelio Monteiro

    2009-01-01

    The pressure vessels of the Angra II and Angra III nuclear power plants, which are of large thickness, have as one of their structural components the 20 MnMo Ni 55 steel. The acoustoelastic evaluation carried out through non-destructive ultrasonic tests was based on the variation of the speed of ultrasonic shear waves of normal incidence as a function of the stress applied in the material using the acoustic birefringence technique, which considers the fractional difference of the speeds of two ultrasonic waves propagating in orthogonal directions. In this work two experiments were carried out. In the first one, a new method for acquisition of ultrasonic signals for joint application with this technique of stress analysis was evaluated by comparison with the conventional one. The aim was to determine its potential and limitations for application in materials up to 120 mm of thickness. In the second experiment, the acoustoelastic behavior of the 20 MnMo Ni 55 steel was studied. The new method of acquiring ultrasonic signals led to satisfactory results and was used in the study of the acoustoelastic behavior of the 20 MnMoNi 55 steel. The acoustoelastic analysis indicated that the material has an anisotropic and heterogeneous behavior. The acoustoelastic constant of this material, obtained experimentally from the analysis of the graphs of the material behavior (birefringence x stress) under compression tests performed on specimens of the 20 MnMo Ni 55 steel, was used for the quantitative stress analysis. A specimen of the 20 MnMo Ni 55 steel was subjected to a bending test to carry out a qualitative stress analysis through the difference between the values of the birefringence obtained during loading (B) and before loading (Bo) in every point studied. With the obtained results it was possible to identify qualitative and quantitatively the regions of the specimen under compressive and tensile stresses. The execution of these tests allowed to verify the efficiency of

  7. The effects of Ni, Mo, Ti and Si on the mechanical properties of Cr free Mn steel (Fe-25Mn-5Al-2C)

    International Nuclear Information System (INIS)

    Schuon, S.R.

    1982-01-01

    The FeMnAlC alloys may hold potential as Cr-free replacements for high strategic material iron base superalloys, but little is known about their intermediate temperature (650 C to 870 C) mechanical properties. The effects of alloying elements on the mechanical properties of model FeMnAlC alloys were studied. Results showed that modified FeMnAlC alloys had promising short term, intermediate temperature properties but had relatively poor stress rupture lives at 172 MPa and 788 C. Room temperature and 788 C tensile strength of FeMnAlC alloys were better than common cast stainless steels. Changes in room temperature tensile and 788 C tensile strength and ductility, and 788 C stress rupture life were correlated with changes in Ni, Mo, Ti, and Si levels due to alloying effects on interstitial carbon levels and carbide morphology. Fe-25Mn-5Al-2C had a very poor stress rupture life at 172 MPa and 788 C. Addition of carbide-forming elements improved the stress rupture life

  8. Stability and electronic properties of Cd0.75Mn0.25S and Cd0.75Mn0.25Se in B3 phase

    Energy Technology Data Exchange (ETDEWEB)

    Rani, Anita [Guru Nanak College for Girls, Sri Muktsar Sahib, Punjab (India); Kumar, Ranjan [Panjab University, Department of Physics, Chandigarh (India)

    2015-08-15

    We studied the structural, elastic, spin-polarized electronic band structures and magnetic properties of the diluted magnetic semiconductor Cd{sub 1-x}Mn{sub x}S and Cd{sub 1-x} Mn{sub x}Se in zinc blende phase (B3) for x = 0.25 using ab initio method. The calculations were performed by using density functional theory as implemented in the Spanish Initiative for Electronic Simulations with Thousands of Atoms code using local density approximation. Calculated electronic band structures and magnetic properties of Cd{sub 1-x}Mn{sub x}S are discussed in terms of contribution of Mn 3d{sup 5} 4s{sup 2}, Cd 4d{sup 10} 5s{sup 2}, S 3s{sup 2} 3p{sup 4} orbitals. The total magnetic moment is found to be 5.00 μ{sub b} for Cd{sub 1-x}Mn{sub x}S and Cd{sub 1-x}Mn{sub x}Se at x = 0.25. This value indicates that Mn atom adds no hole carrier to the perfect CdS crystal. We determine the spin-exchange splitting energies produced by Mn 3d states, s-d exchange constant N{sub 0}α, and p-d exchange constant N{sub 0}β. We found that Mn-doped systems are ferromagnetic. Calculated results are in good agreement with previous studies. (orig.)

  9. Effects on Magnetic Properties of GaMnAs Induced by Proximity of Topological Insulator Bi2Se3

    Science.gov (United States)

    Bac, Seul-Ki; Lee, Hakjoon; Lee, Sangyeop; Choi, Seonghoon; Lee, Sanghoon; Liu, X.; Dobrowolska, M.; Furdyna, J. K.

    2018-04-01

    Effects induced by a topological insulator Bi2Se3 on the magnetic properties of an adjacent GaMnAs film have been investigated using transport measurements. We observed three conspicuous effects in the GaMnAs layer induced by the proximity of the Bi2Se3 overlayer. First, our resistivity data as a function of temperature show that the GaMnAs layer adjacent to the Bi2Se3 displayed strongly metallic behavior, as compared with the GaMnAs control specimen. Second, the Curie temperature of the GaMnAs in the bilayer was observed to be higher than that of the control layer, in our case by nearly a factor of two. Finally, we observed significant changes in the in-plane magnetic anisotropy of the GaMnAs in the bilayer, in the form of much higher values of both cubic and uniaxial anisotropy parameters. This latter feature manifests itself in a rather spectacular increase of the coercive field observed in magnetization reversal across the in-plane hard axis. These results suggest that proximity of an adjacent Bi2Se3 layer represents an important tool for modifying and controlling the ferromagnetic properties of GaMnAs film, and could thus be used to optimize this and similar materials for applications in spintronic devices.

  10. CVD synthesis of large-area, highly crystalline MoSe2 atomic layers on diverse substrates and application to photodetectors.

    Science.gov (United States)

    Xia, Jing; Huang, Xing; Liu, Ling-Zhi; Wang, Meng; Wang, Lei; Huang, Ben; Zhu, Dan-Dan; Li, Jun-Jie; Gu, Chang-Zhi; Meng, Xiang-Min

    2014-08-07

    Synthesis of large-area, atomically thin transition metal dichalcogenides (TMDs) on diverse substrates is of central importance for the large-scale fabrication of flexible devices and heterojunction-based devices. In this work, we successfully synthesized a large area of highly-crystalline MoSe2 atomic layers on SiO2/Si, mica and Si substrates using a simple chemical vapour deposition (CVD) method at atmospheric pressure. Atomic force microscopy (AFM) and Raman spectroscopy reveal that the as-grown ultrathin MoSe2 layers change from a single layer to a few layers. Photoluminescence (PL) spectroscopy demonstrates that while the multi-layer MoSe2 shows weak emission peaks, the monolayer has a much stronger emission peak at ∼ 1.56 eV, indicating the transition from an indirect to a direct bandgap. Transmission electron microscopy (TEM) analysis confirms the single-crystallinity of MoSe2 layers with a hexagonal structure. In addition, the photoresponse performance of photodetectors based on MoSe2 monolayer was studied for the first time. The devices exhibit a rapid response of ∼ 60 ms and a good photoresponsivity of ∼ 13 mA/W (using a 532 nm laser at an intensity of 1 mW mm(-2) and a bias of 10 V), suggesting that MoSe2 monolayer is a promising material for photodetection applications.

  11. Cationic Intermixing and Reactivity at the La2 Mo2 O9 /La0.8 Sr0.2 MnO3-δ Solid Oxide Fuel Cell Electrolyte-Cathode Interface.

    Science.gov (United States)

    Ravella, Uday K; Liu, Jingjing; Corbel, Gwenaël; Skinner, Stephen J; Lacorre, Philippe

    2016-08-23

    Among standard high-temperature cathode materials for solid oxide fuel cells, La0.8 Sr0.2 MnO3-δ (LSM) displays the least reactivity with the oxide-ion conductor La2 Mo2 O9 (LMO), yet a reaction is observed at high processing temperatures, identified by using XRD and focused ion beam secondary-ion mass spectrometry (FIB-SIMS) after annealing at 1050 and 1150 °C. Additionally, Sr and Mn solutions were deposited and annealed on LMO pellets, as well as a Mo solution on a LSM pellet. From these studies several reaction products were identified by using XRD and located by using FIB-SIMS on the surface of pelletised samples. We used depth profiling to show that the reactivity extended up to ∼10 μm from the surface region. If Sr was present, a SrMoO4 -type scheelite phase was always observed as a reaction product, and if Mn was present, LaMnO3+δ single crystals were observed on the surface of the LMO pellets. Additional phases such as La2 MoO6 and La6 MoO12 were also detected depending on the configuration and annealing temperature. Reaction mechanisms and detailed reaction formulae are proposed to explain these observations. The strongest driving force for cationic diffusion appears to originate from Mo(6+) and Mn(3+) cations, rather than from Sr(2+) . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Refinement of grain structure in 20 MnNiMo (SA508C) steel

    International Nuclear Information System (INIS)

    Sheng Zhongqi; Xiao Hong; Peng Feng; Zou Min

    1997-04-01

    The size of prior austenite grains and bainitic colonies of 20 MnNiMo (SA508C) steel (a reactor pressure vessel steel) after normal heat treatment is measured and its controlling factors are discussed. Results show that low aluminium content can induce serious mixed structure with fine and coarse grains in prior austenite. Fast cooling rate can promote refinement of bainitic colonies. Further refinement of grains can be obtained by inter-critical quenching. (5 figs., 1 tab.)

  13. Integrated MoSe2 with n+p-Si photocathodes for solar water splitting with high efficiency and stability

    Science.gov (United States)

    Huang, Guanping; Mao, Jie; Fan, Ronglei; Yin, Zhihao; Wu, Xi; Jie, Jiansheng; Kang, Zhenhui; Shen, Mingrong

    2018-01-01

    Many earth-abundant transition metal dichalcogenides (TMDs) have been employed as catalysts for H2 evolution reaction (HER); however, their impactful integration onto photocathodes for photoelectrochemical (PEC) HER is less developed. In this study, we directly sputtered a MoSe2 catalyst onto an n+p-Si photocathode for efficient and stable PEC-HER. An onset potential of 0.4 V vs. RHE, a saturated photocurrent of 29.3 mA/cm2, a fill factor of 0.32, and an energy conversion efficiency of 3.8% were obtained under 100 mA/cm2 Xe lamp illumination. Such superior PEC properties were ascribed to the nearly vertically standing two dimensional MoSe2 rough surface layer and the sharp interface between Si and MoSe2 with small charge transfer resistance. The balance between the reflectivity of the electrode surface and the absorptivity of MoSe2 was also discussed. In addition, the MoSe2 layer can protect the n+p-Si photocathode with a 120 h stability due to its initial growth on Si with high flatness and compactness. This study provides a path to the effective and scalable growth of TMDs onto the Si photocathode aiming for high efficiency and stability.

  14. Electronic structure and exchange interactions in diluted semimagnetic semiconductors (Zn,Co)Se and (Zn,Mn)Se

    Science.gov (United States)

    Mašek, J.

    1991-05-01

    A comparative study of the electronic structure of (Zn,Co)Se and (Zn,Mn)Se is done by using a tight-binding version of the coherent potential approximation. The densities of states, relevant for a photoemission experiment, are calculated for a magnetically disordered phase. The exchange constant Jpd is obtained from the splitting of the valence band top in the ferromagnetic phase of the mixed crystal; Jdd is estimated from the energy of a spin reversal. We explain the large exchange constant in the Co-based systems as a result of efficient hybridization of the d-states with the valence band.

  15. Interpretation of dc and ac conductivity of Ag2O–SeO2–MoO3 glass-nanocomposite-semiconductor

    International Nuclear Information System (INIS)

    Bhattacharya, Sanjib; Kundu, Ranadip; Das, Anindya Sundar; Roy, Debasish

    2015-01-01

    Highlights: • Polaron hopping. • Dc and ac conductivity. • Mott's model and Greave's model. • Ag 2 MoO 4 , Ag 2 Mo 2 O 7 and Ag 6 Mo 10 O 33 nanoparticles and SeO 3 and SeO 4 nanoclusters. • XRD and FESEM studies. - Abstract: A new type of semiconducting glass-nanocomposites 0.3Ag 2 O–0.7 (xMoO 3 –(1 − x) SeO 2 ) is prepared by melt-quenching route. The formation of Ag 2 MoO 4 , Ag 2 Mo 2 O 7 and Ag 6 Mo 10 O 33 nanoparticles and SeO 3 and SeO 4 nanoclusters in glass-nanocomposites has been confirmed from X-ray diffraction (XRD) and field emission scanning electron microscopic (FESEM) studies. Fourier transform infrared (FTIR) spectroscopy is employed to find out Se−O stretching vibration as well as stretching vibrations of Mo 2 O 7 2− ions. The dc conductivity of them is studied on the light of polaron hopping approach in a wide temperature range. At low temperatures, variable range hopping model (Mott's model) is employed to analyze the conductivity data. Greave's model is used to predict temperature dependent variable range hopping in the high temperature region. Frequency dependent ac conductivity is well explained on the basis of tunneling. I–V characteristics of the as-prepared samples have also been investigated

  16. Mo, Mn and La doped TiO{sub 2}: Synthesis, characterization and photocatalytic activity for the decolourization of three different chromophoric dyes

    Energy Technology Data Exchange (ETDEWEB)

    Umar, K.; Haque, M.M. [Department of Chemistry, Aligarh Muslim University, Aligarh 202 002 (India); Muneer, M., E-mail: readermuneer@gmail.com [Department of Chemistry, Aligarh Muslim University, Aligarh 202 002 (India); Harada, T.; Matsumura, M. [Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka 560-8531 (Japan)

    2013-11-25

    Highlights: •Detail study on synthesis, characterization and photocatalytic activity of doped-TiO{sub 2}. •SEM images indicates partial crystalline nature with rough surfaces. •The XRD analysis shows the partial crystalline nature and anatase phase. •The UV–Vis absorption spectra showed λ{sub max} shift towards longer wavelength. •TiO{sub 2} with dopant 0.75% (Mo), 1.0% (Mn, La) showed best photocatalytic efficiency. -- Abstract: Nanocrystalline TiO{sub 2} particles doped with different concentrations of Molybdenum (Mo), Manganese (Mn) and Lanthanum (La) (0.25–1.0%) were synthesized using sol–gel method and characterized by standard analytical techniques such as X-ray diffraction (XRD), UV–Vis spectroscopy and Scanning Electron Microscopy (SEM). The XRD analysis shows the partial crystalline nature and anatase phase. The SEM images of undoped and doped TiO{sub 2} at different magnifications also show the partial crystalline nature with rough surfaces. The photocatalytic activity of the synthesized particles (TiO{sub 2} doped with Mo, Mn and La) was tested by studying the decolourization of three different chromophoric dyes such as Acid Red 88 (azo dye), Gentian Violet (triphenylmethane dye) and Remazol Brilliant Blue R (anthraquinone dye) as a function of time on irradiation in aqueous suspension in an immersion well photochemical reactor with a 500 W halogen linear lamp in the presence of atmospheric oxygen. The results indicate that TiO{sub 2} with dopant concentration of 0.75% (Mo) and 1.0% (Mn, La) showed the highest photocatalytic activity as compared to the other dopant concentrations for the decolourization of all the dyes.

  17. Optical detection of organophosphorus compounds based on Mn-doped ZnSe d-dot enzymatic catalytic sensor.

    Science.gov (United States)

    Gao, Xue; Tang, Guangchao; Su, Xingguang

    2012-01-01

    In this paper, we report a sensitive and selective method for detection of organophosphorus compounds (OPs) based on Mn:ZnSe d-dots-enzyme-hydrogen peroxide (H(2)O(2)) fluorescence quenching system. Acetylcholine esterase (AChE) can hydrolyze acetylcholine (ACh) to choline. Subsequently, choline oxidase (ChOx) oxidizes choline to generate H(2)O(2). The enzyme-generated H(2)O(2) can quench the fluorescence of Mn:ZnSe d-dots. When paraoxon are introduced in solution, it can interact with the active centers of AChE and decrease the enzyme activity. This leads to the decrease of the H(2)O(2) production and then the fluorescence quenching rate of Mn:ZnSe d-dots. Experimental results showed that the enzyme inhibition percentage of Mn:ZnSe d-dots-ChOx-AChE-ACh system was proportional to the logarithm of paraoxon in the range 4.84×10(-11) to 4.84×10(-6) mol/L with the detection limit (S/N=3) of 1.31×10(-11) mol/L. The proposed biosensor has been employed for quick determination of paraoxon in tap water and milk samples with satisfactory reproducibility and accuracy. This nano-biosensor was proved to be sensitive, rapid, simple and tolerance of most interfering substances. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Influence of pH on luminescence from water-soluble colloidal Mn-doped ZnSe quantum dots capped with different mercaptoacids

    International Nuclear Information System (INIS)

    Hardzei, Maryia; Artemyev, Mikhail

    2012-01-01

    Water-soluble ZnSe/ZnS core–shell quantum dots with ZnSe core doped by manganese ions show different luminescence response to pH changes in aqueous solutions depending on the type of solubilizing agents (thioglycolic acid, mercaptoundecanoic acid, sodium mercaptopropylsulfonate). In the case of long-chain mercaptoundecanoic acid only excitonic emission is affected by pH changes. Short-chain thioglycolic acid brings about equal excitonic/Mn emission variations with pH, while mercaptopropylsulfonate-stabilized quantum dots are insensitive to pH. The mechanism discussed here is based on the competition between different relaxation channels for excited excitons in ZnSe: excitonic radiative recombination, energy transfer to Mn ion and the photogenerated electron trapping due to the presence of protonated carboxyl group. ZnSe:Mn/ZnS quantum dots stabilized with long-chain mercaptoacids may be used as a new type of fluorescence ratiometric pH-sensor or indicator. - Highlights: ► Prepared ZnSe:Mn/ZnS quantum dots capped with different mercaptoacids in water. ► Photoluminescence intensity of ZnSe:Mn/ZnS quantum dots varied with pH. ► Character of luminescence variations depends on the sort of mercaptoacid capping. ► Competition between different excitonic relaxation channels for different caps.

  19. Synthesis and Characterization of Mixed Chalcogen Triangular Complexes with New Mo-3(mu(3)-S)(mu(2)-Se-2)(3)(4+) and M-3(mu(3)-S)mu(2)-Se)(3)(4+) (M = Mo, W) Cluster Cores

    DEFF Research Database (Denmark)

    Gushchin, Artem; Ooi, Bee Lean; Harris, Pernille

    2009-01-01

    In our pursuit of mixed chalcogen-bridged cluster complexes, solids of the compositions Mo3SSe6Br4 and W3SSe6Br4 were prepared using high-temperature synthesis from the elements. Treatment of Mo3SSe6Br4 with Bu4NBr in a vibration mill yielded (Bu4N)(3)([Mo-3(mu(3)-S)(mu(2)-Se-2)(3)Br-6]Br} (I). Its......), was isolated and its structure determined using X-ray crystallography. W3SSe6Br4 upon reaction with H3PO2 gave a mixture of all of the [W3SxSe4-x(H2O)(9)](4+) species. After repeated chromatography, crystals of {[W-3(mu(3)-S)(mu(2)-Se)(3)(H2O)(7)Cl--(2)](2)CB[6]}Cl-4 center dot 12H(2)O (IV) were crystallized...

  20. First-principles study of MoS2 and MoSe2 nanoclusters in the framework of evolutionary algorithm and density functional theory

    Science.gov (United States)

    Hashemi, Zohreh; Rafiezadeh, Shohreh; Hafizi, Roohollah; Hashemifar, S. Javad; Akbarzadeh, Hadi

    2018-04-01

    Evolutionary algorithm is combined with full-potential ab initio calculations to investigate conformational space of (MoS2)n and (MoSe2)n (n = 1-10) nanoclusters and to identify the lowest energy structural isomers of these systems. It is argued that within both BLYP and PBE functionals, these nanoclusters favor sandwiched planar configurations, similar to their ideal planar sheets. The second order difference in total energy (Δ2 E) of the lowest energy isomers is computed to estimate the abundance of the clusters at different sizes and to determine the magic sizes of (MoS2)n and (MoSe2)n nanoclusters. In order to investigate the electronic properties of nanoclusters, their energy gap is calculated by several methods, including hybrid functionals (B3LYP and PBE0), GW approach, and Δ scf method. At the end, the vibrational modes of the lowest lying isomers are calculated by using the force constants method and the IR active modes of the systems are identified. The vibrational spectra are used to calculate the Helmholtz free energy of the systems and then to investigate abundance of the nanoclusters at finite temperatures.

  1. Bandgap renormalization and work function tuning in MoSe2/hBN/Ru(0001) heterostructures.

    Science.gov (United States)

    Zhang, Qiang; Chen, Yuxuan; Zhang, Chendong; Pan, Chi-Ruei; Chou, Mei-Yin; Zeng, Changgan; Shih, Chih-Kang

    2016-12-14

    The van der Waals interaction in vertical heterostructures made of two-dimensional (2D) materials relaxes the requirement of lattice matching, therefore enabling great design flexibility to tailor novel 2D electronic systems. Here we report the successful growth of MoSe 2 on single-layer hexagonal boron nitride (hBN) on the Ru(0001) substrate using molecular beam epitaxy. Using scanning tunnelling microscopy and spectroscopy, we found that the quasi-particle bandgap of MoSe 2 on hBN/Ru is about 0.25 eV smaller than those on graphene or graphite substrates. We attribute this result to the strong interaction between hBN/Ru, which causes residual metallic screening from the substrate. In addition, the electronic structure and the work function of MoSe 2 are modulated electrostatically with an amplitude of ∼0.13 eV. Most interestingly, this electrostatic modulation is spatially in phase with the Moiré pattern of hBN on Ru(0001) whose surface also exhibits a work function modulation of the same amplitude.

  2. Spin-exciton interaction and related micro-photoluminescence spectra of ZnSe:Mn DMS nanoribbon.

    Science.gov (United States)

    Hou, Lipeng; Zhou, Weichang; Zou, Bingsuo; Zhang, Yu; Han, Junbo; Yang, Xinxin; Gong, Zhihong; Li, Jingbo; Xie, Sishen; Shi, Li-Jie

    2017-03-10

    For their spintronic applications the magnetic and optical properties of diluted magnetic semiconductors (DMS) have been studied widely. However, the exact relationships between the magnetic interactions and optical emission behaviors in DMS are not well understood yet due to their complicated microstructural and compositional characters from different growth and preparation techniques. Manganese (Mn) doped ZnSe nanoribbons with high quality were obtained by using the chemical vapor deposition (CVD) method. Successful Mn ion doping in a single ZnSe nanoribbon was identified by elemental energy-dispersive x-ray spectroscopy mapping and micro-photoluminescence (PL) mapping of intrinsic d-d optical transition at 580 nm, i.e. the transition of 4 T 1 ( 4 G) →  6 A 1 ( 6 s),. Besides the d-d transition PL peak at 580 nm, two other PL peaks related to Mn ion aggregates in the ZnSe lattice were detected at 664 nm and 530 nm, which were assigned to the d-d transitions from the Mn 2+ -Mn 2+ pairs with ferromagnetic (FM) coupling and antiferromagnetic (AFM) coupling, respectively. Moreover, AFM pair formation goes along with strong coupling with acoustic phonon or structural defects. These arguments were supported by temperature-dependent PL spectra, power-dependent PL lifetimes, and first-principle calculations. Due to the ferromagnetic pair existence, an exciton magnetic polaron (EMP) is formed and emits at 460 nm. Defect existence favors the AFM pair, which also can account for its giant enhancement of spin-orbital coupling and the spin Hall effect observed in PRL 97, 126603(2006) and PRL 96, 196404(2006). These emission results of DMS reflect their relation to local sp-d hybridization, spin-spin magnetic coupling, exciton-spin or phonon interactions covering structural relaxations. This kind of material can be used to study the exciton-spin interaction and may find applications in spin-related photonic devices besides spintronics.

  3. Hierarchical Mo_9Se_1_1 nanoneedles on nanosheet with enhanced electrochemical properties as a battery-type electrode for asymmetric supercapacitors

    International Nuclear Information System (INIS)

    Aziz, Radhiyah Abd; Muzakir, Saifful Kamaluddin; Misnon, Izan Izwan; Ismail, Jamil; Jose, Rajan

    2016-01-01

    A hierarchical nanostructure of orthorhombic Mo_9Se_1_1 is synthesized by colloidal processing and evaluated for its application as an electrode for asymmetric supercapacitors (ASCs). The material is characterized by X-ray and electron diffraction, X-ray photoelectron spectroscopy, gas adsorption studies, scanning and transmission electron microscopies for their crystal structure, surface and morphological properties. These studies show that colloidal synthesized Mo_9Se_1_1 has a hierarchical structure in the form of nanoneedles grown on its nanosheet. The nanoneedles are single crystalline with circular cross-section of diameter ∼10–20 nm at the root, ∼6–10 nm at the tip and length ∼5–10 μm. Electrochemical properties of the material are studied in detail in three moderately conductive alkaline electrolytes, viz. 3 M of LiOH, NaOH, and KOH employing cyclic voltammetry, galvanostatic charge discharge cycling, and electrochemical impedance spectroscopy. The Mo_9Se_1_1 electrodes showed superior specific capacitance (C_S ∼510 F g"−"1) and larger voltage window (up to 0.7 V) in the LiOH electrolyte. We show that the excellent electrochemical properties of Mo_9Se_1_1 can be assigned to the hierarchical microstructure and its one-dimensional channel structure; those accommodate and facilitate fast redox reactions for electrons and ions. Furthermore, ASCs were fabricated using the Mo_9Se_1_1 as a battery-type electrode and commercial activated carbon as supercapacitor electrode; the devices showed larger voltage window, energy density (E_S), and power density (P_S) than many of the devices reported in literature. The ASCs showed six times higher E_S while maintaining similar P_S than a control supercapacitor fabricated using activated carbon(AC). - Highlights: • Hierarchical Mo_9Se_1_1 nanoneedles on its nanosheets synthesized via colloidal route. • Electrochemical property of Mo_9Se_1_1 is evaluated in moderate alkaline electrolytes. • Mo_9Se_1

  4. Layered MoSe2/Bi2WO6 composite with P-N heterojunctions as a promising visible-light induced photocatalyst

    Science.gov (United States)

    Xie, Taiping; Liu, Yue; Wang, Haiqiang; Wu, Zhongbiao

    2018-06-01

    In this paper, layered MoSe2/Bi2WO6 composites were fabricated by a simple bath sonication method for photocatalytic applications. Their photocatalytic performances were then investigated via the photocatalytic oxidation of gaseous toluene under visible-light irradiation. As a result, 1.5%-MoSe2/Bi2WO6 catalyst showed the highest activity with a degradation rate of nearly 80% during three-hour visible-light irradiation. The k value determined of 1.5%-MoSe2/Bi2WO6 was approximately 6 times higher than that of pure Bi2WO6 and 7 times higher compared with pure MoSe2. After a series of characterizations, it was concluded that the p-n heterojunctions of MoSe2/Bi2WO6 composites with strong interlayer interactions could effectively prolong the life time of photoinduced electron-hole pairs. And both the contents of surface superoxide and hydroxyl radicals were thereby increased, benefitting the photocatalytic process. Furthermore, the hydroxyl radicals and holes were found to be the major active species. This work provided a way to design photocatalyst with enhanced visible-light driven photoactivity toward indoor air pollutants purification.

  5. Transition Metal Complexes of Cr, Mo, W and Mn Containing η1(S)-2,5-Dimethylthiophene, Benzothiophene and Dibenzothiophene Ligands

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, Michael [Iowa State Univ., Ames, IA (United States)

    2000-09-21

    The UV photolysis of hexanes solutions containing the complexes M(CO)6 (M=Cr, Mo, W) or CpMn(CO)3 (Cp=η5-C5H5) and excess thiophene (T*) (T*=2,5-dimethylthiophene (2,5-Me2T), benzothiophene (BT), and dibenzothiophene (DBT)) produces the η1(S)-T* complexes (CO)5M(η1(S)-T*) 1-8 or Cp(CO)2Mn1(S)-T*)9-11, respectively. However, when T*=DBT, and M=Mo, a mixture of two products result which includes the η1(S)-DBT complex (CO)5Mo1(S)-DBT) 4a and the unexpected π-complex (CO)3Mo(η{sup 6}-DBT) 4b as detected by 1H NMR. The liability of the η1(S)-T* ligands is illustrated by the rapid displacement of DBT in the complex (CO)5W(η1(S)-DBT) (1) by THF, and also in the complexes (CO)5Cr(η1(S)-DBT) (5) and CpMn(CO)21(S)-DBT) (9) by CO (1 atm) at room temperature. Complexes 1-11 have been characterized spectroscopically (1H NMR, IR) and when possible isolated as analytically pure solids (elemental analysis, EIMS). Single crystal, X-ray structural determinations are reported for (Cη)5W(η1(S)-DBT) and Cp(CO)2Mn1(S)-DBT).

  6. Anomalous carrier life-time relaxation mediated by head group interaction in surface anchored MnSe quantum dots conjugated with albumin proteins

    Energy Technology Data Exchange (ETDEWEB)

    Sarma, Runjun; Mohanta, Dambarudhar, E-mail: best@tezu.ernet.in

    2017-02-01

    We report on the radiative emission decay dynamics of a less known, γ-phase manganese selenide quantum dot system (MnSe QDs) subjected to bio-functionalization. A short-ligand thioglycolic acid (TGA), and a long-chain sodium dodecyl sulfate (SDS) surfactants were used as surface anchors prior bioconjugation with albumin proteins (BSA). Time resolved photoluminescence (TR-PL) spectra of the QDs have revealed bi-exponential decay trends with the fast (τ{sub 1}) and slow (τ{sub 2}) decay parameters assigned to the core state recombination and surface trapped excitons; respectively. The average lifetime (τ{sub avg}) was found to get shortened from a value of ∼0.87 ns–0.72 ns in unconjugated and BSA conjugated MnSe-TGA QDs; respectively. Conversely, MnSe-SDS QDs with BSA conjugation exhibited nearly four-fold enhancement of τ{sub avg} with respect to its unconjugated counterpart. Moreover, a considerable amount of Förster resonance energy transfer (FRET) was found to occur from the TGA coated MnSe QDs to BSA and with an ensuing efficiency of ∼61%. The origin of anomalous carrier life-time relaxation features has also been encountered through a simplified model as regards head group interaction experienced by the MnSe QDs with different surfactant types. Exploiting luminescence decay characteristics of a magneto-fluorescent candidate could find immense scope in diverse biological applications including assays, labeling and imaging. - Highlights: • Surface anchored manganese selenide quantum dots (MnSe QDs) have been synthesized via a physico-chemical reduction route. • Time resolved luminescence spectra of the QDs have displayed bi-exponential decay trend. • Thioglycolic acid (TGA) coated QDs exhibited shorter lifetime as compared to sodium dodecyl sulfo-succinate (SDS) coated ones. • Upon BSA conjugation, the average life time is four-fold enhanced in MnSe-SDS QDs. • An efficient FRET process has been revealed in BSA conjugated TGA coated MnSe QDs.

  7. Edge Epitaxy of Two-dimensional MoSe2 and MoS2 Nanosheets on One-dimensional Nanowires

    KAUST Repository

    Chen, Junze

    2017-06-05

    Rational design and synthesis of heterostructures based on transition metal dichalcogenides (TMDs) have attracted increasing interests because of their promising applications in electronics, catalysis, etc. However, the construction of epitaxial heterostructures with interface at the edges of TMD nanosheets (NSs) still remains great challenge. Here, we report a strategy for controlled synthesis of a new type of heterostructures in which TMD NSs, including MoS2 and MoSe2, vertically grow along the longitudinal direction of one-dimensional (1D) Cu2-xS nanowires (NWs) in an epitaxial manner. The obtained Cu2-xS-TMD heterostructures with tunable loading amount and lateral size of TMD NSs are achieved by the consecutive growth of TMD NSs on Cu2-xS NWs through the gradually injection of chalcogen precursors. After cation exchange of Cu in Cu2-xS-TMD heterostructures with Cd, the obtained CdS-MoS2 heterostructures remained their original architectures. Compared to the pure CdS NWs, the CdS-MoS2 heterostructures with 7.7 wt% loading of MoS2 NSs exhibit the best performance in the photocatalytic hydrogen evolution reaction with the H2 production rate up to 4,647 μmol·h-1·g-1, about 58 times that catalyzed with pure CdS NWs. Our synthetic strategy opens up a new way for the controlled synthesis of TMD-based heterostructures which could have various promising applications.

  8. Rational synthesis of graphene-encapsulated uniform MnMoO4 hollow spheres as long-life and high-rate anodes for lithium-ion batteries.

    Science.gov (United States)

    Wei, Huaixin; Yang, Jun; Zhang, Yufei; Qian, Yong; Geng, Hongbo

    2018-03-29

    In this manuscript, the graphene-encapsulated MnMoO 4 hollow spheres (MnMoO 4 @G) synthesized by an effective strategy were reported. Benefiting from the intriguing hybrid architecture of hollow structure and conductive graphene network, the MnMoO 4 @G composite displays superior electrochemical performance with high specific capacity of 1142 mA h g -1 , high reversible cycling stability of 921 mA h g -1 at a current density of 100 mA g -1 after 70 cycles, and stable rate performance (around 513 mA h g -1 at a current density of 4.0 A g -1 ). The remarkable battery performance can be attributed to the rational design of the architecture, which not only ensures the fast transport of electrons and lithium ions within the electrode material, but also effectively relax the stress induced by the insertion/extraction of lithium ions. This facile synthetic method can extend to other transition metal oxides with large volume excursions and poor electric conductivity and promotes the development of transition metal oxides as high-performance LIB anode material. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. First-principles investigation of the bulk and low-index surfaces of MoSe_2

    International Nuclear Information System (INIS)

    Mirhosseini, Hossein; Roma, Guido; Kiss, Janos; Felser, Claudia

    2014-01-01

    In the framework of density functional theory, the geometry, electronic structure, and magnetic properties of the bulk and low index surfaces of MoSe_2 have been studied. We have carried out calculations with various exchange-correlation functionals to select one which is able to describe the van der Waals (vdW) interactions and gives the best geometry compared with experiments. The inclusion of the vdW forces, however, does not guarantee a reliable description for the geometry of this compound: some vdW functionals strongly overestimate the interlayer distance, similar to GGA functionals. Our investigation shows that the recently introduced optB86bvdW functional yields the best results for MoSe_2. The vdW functionals have less impact on the electronic structure: the differences between the band structures of the experimental atomic structure, calculated by the vdW-DF and PBE functionals are marginal. We have tried the HSE06 hybrid functional as well but the results are not satisfactory: the overestimated interlayer distance leads to a significant overestimation of the band gap. The band structure of the bulk and monolayer is calculated and by the analysis of the bands character the indirect to direct band-gap transition is explained. The surface energy, work function and band structure of the surfaces are calculated as well. The role of the MoSe_2 buffer layer in Cu(In,Ga)Se_2 based solar cells is discussed by considering the work function values. (authors)

  10. The evaluation of Cu, Zn, Mn, and Se concentrations in the hair of South American camelids

    Directory of Open Access Journals (Sweden)

    Milada Holasová

    2017-01-01

    Full Text Available The aim of this study was to monitor the content of trace elements in the hair of South American camelids and to evaluate the effect of coat colour, species, age, and sex on their concentration in the hair. The samples were collected from 77 animals – 23 llamas (Llama guanicoe f. gllama and 54 alpacas (Llama guanicoe f. pacos during a spring health check. The concentrations of copper (Cu, zinc (Zn, and manganese (Mn were determined by Flame Atomic Absorption Spectrometry and selenium (Se by Hydride Generation Atomic Absorption Spectrometry. We found the following concentrations (mean ± standard deviation; mg/kg dry matter in the llama hair: Cu 9.70 ± 4.69; Zn 145.20 ± 21.07; Mn 12.49 ± 10.14; Se 0.25 ± 0.14. In alpaca hair we found the following concentrations: Cu 10.22 ± 2.90; Zn 129.81 ± 19.01; Mn 12.67 ± 13.85; Se 0.48 ± 0.24. We found a significant difference between llamas and alpacas in Zn and Se concentrations in the hair. From all the evaluated factors we found that coat colour had the highest effect on Mn and Se concentration. Dark haired animals had significantly higher concentrations of these trace elements than other coloured groups. The evaluation of the concentration of trace elements in the hair of llamas has a potential to be used for the evaluation of long-term status of trace elements in the body; however, it is necessary to continue with experimental work in this area. Our findings can serve as a pilot study for further works in this field.

  11. Construction of N-doped carbon@MoSe2 core/branch nanostructure via simultaneous formation of core and branch for high-performance lithium-ion batteries

    International Nuclear Information System (INIS)

    Wang, Jiayu; Peng, Changqing; Zhang, Lili; Fu, Yongsheng; Li, Hang; Zhao, Xianmin; Zhu, Junwu; Wang, Xin

    2017-01-01

    Highlights: •N-doped carbon@MoSe 2 core/branch was prepared via a facile calcining method. •N-doped carbon core and MoSe 2 branch can be simultaneously constructed. •PANI played vital roles in the reduction of MoO 3 and elemental Se. •The core/branch structure remarkably improved the lithium storage performance. -- Abstract: Here, we report a one-step simultaneous-construction approach to synthesize N-doped carbon@MoSe 2 core/branch nanostructures by heating a mixture of MoO 3 /PANI hybrids and Se powders in argon atmosphere, without requiring a cumbersome multi-step process or highly toxic reducing agents. It is found that in the construction process, PANI played a crucial role in the reduction of MoO 3 and Se to form MoSe 2 nanosheet branches, while PANI itself was decomposed and carbonized into N-doped carbon nanorod cores. Interestingly, the coexistence of 1D and 2D nanostructures in the N-doped carbon@MoSe 2 core/branch system leads to excellent lithium storage performance, including a large discharging capacity of 1275 mA h g −1 , a high reversible lithium extraction capacity of 928 mA h g −1 and a coulombic efficiency of 72.8%. After 100 cycles, the NDC@MS electrode still delivers a reversible capacity of 906 mA h g −1 with a capacity retention ratio of 97.6%. The superior electrochemical properties can be attributed to the unique core/branch nanostructure of NDC@MS and the synergistic effect between the N-doped carbon nanorod cores and MoSe 2 nanosheet branches.

  12. Structural properties of Bi{sub 2−x}Mn{sub x}Se{sub 3} thin films grown via molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Babakiray, Sercan; Johnson, Trent A.; Borisov, Pavel; Holcomb, Mikel B.; Lederman, David, E-mail: david.lederman@mail.wvu.edu [Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315 (United States); Marcus, Matthew A. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Tarafder, Kartick [Department of Physics, BITS-Pilani Hyderabad Campus, Secunderabad, Andhra Pradesh 500078 (India)

    2015-07-28

    The effects of Mn doping on the structural properties of the topological insulator Bi{sub 2}Se{sub 3} in thin film form were studied in samples grown via molecular beam epitaxy. Extended x-ray absorption fine structure measurements, supported by density functional theory calculations, indicate that preferential incorporation occurs substitutionally in Bi sites across the entire film volume. This finding is consistent with x-ray diffraction measurements which show that the out of plane lattice constant expands while the in plane lattice constant contracts as the Mn concentration is increased. X-ray photoelectron spectroscopy indicates that the Mn valency is 2+ and that the Mn bonding is similar to that in MnSe. The expansion along the out of plane direction is most likely due to weakening of the Van der Waals interactions between adjacent Se planes. Transport measurements are consistent with this Mn{sup 2+} substitution of Bi sites if additional structural defects induced by this substitution are taken into account.

  13. Hierarchical Mo{sub 9}Se{sub 11} nanoneedles on nanosheet with enhanced electrochemical properties as a battery-type electrode for asymmetric supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Aziz, Radhiyah Abd; Muzakir, Saifful Kamaluddin; Misnon, Izan Izwan; Ismail, Jamil; Jose, Rajan, E-mail: rjose@ump.edu.my

    2016-07-15

    A hierarchical nanostructure of orthorhombic Mo{sub 9}Se{sub 11} is synthesized by colloidal processing and evaluated for its application as an electrode for asymmetric supercapacitors (ASCs). The material is characterized by X-ray and electron diffraction, X-ray photoelectron spectroscopy, gas adsorption studies, scanning and transmission electron microscopies for their crystal structure, surface and morphological properties. These studies show that colloidal synthesized Mo{sub 9}Se{sub 11} has a hierarchical structure in the form of nanoneedles grown on its nanosheet. The nanoneedles are single crystalline with circular cross-section of diameter ∼10–20 nm at the root, ∼6–10 nm at the tip and length ∼5–10 μm. Electrochemical properties of the material are studied in detail in three moderately conductive alkaline electrolytes, viz. 3 M of LiOH, NaOH, and KOH employing cyclic voltammetry, galvanostatic charge discharge cycling, and electrochemical impedance spectroscopy. The Mo{sub 9}Se{sub 11} electrodes showed superior specific capacitance (C{sub S} ∼510 F g{sup −1}) and larger voltage window (up to 0.7 V) in the LiOH electrolyte. We show that the excellent electrochemical properties of Mo{sub 9}Se{sub 11} can be assigned to the hierarchical microstructure and its one-dimensional channel structure; those accommodate and facilitate fast redox reactions for electrons and ions. Furthermore, ASCs were fabricated using the Mo{sub 9}Se{sub 11} as a battery-type electrode and commercial activated carbon as supercapacitor electrode; the devices showed larger voltage window, energy density (E{sub S}), and power density (P{sub S}) than many of the devices reported in literature. The ASCs showed six times higher E{sub S} while maintaining similar P{sub S} than a control supercapacitor fabricated using activated carbon(AC). - Highlights: • Hierarchical Mo{sub 9}Se{sub 11} nanoneedles on its nanosheets synthesized via colloidal route. • Electrochemical

  14. Wssv y temperatura, inmunoestimulantes, vitaminas... ¿cómo se relaciona todo?

    OpenAIRE

    Rodriguez, Jenny; Echeverría, Fabrizio; Sonneholznher, Stanislaus; Molina, César; Gullian, Mariel

    2001-01-01

    WSSV y temperatura, inmunoestimulantes, vitaminas... ¿Cómo se relaciona todo? Los experimentos desarrollados a la fecha indican que a temperatura de 33°C disminuye tanto la prevalencia (porcentaje de animales positivos) como la intensidad de la infección en juveniles y en larvas (Boletín Septiembre 15).

  15. General synthesis of hierarchical C/MOx@MnO2 (M=Mn, Cu, Co) composite nanofibers for high-performance supercapacitor electrodes.

    Science.gov (United States)

    Nie, Guangdi; Lu, Xiaofeng; Chi, Maoqiang; Gao, Mu; Wang, Ce

    2018-01-01

    Improving the conductivity and specific surface area of electrospun carbon nanofibers (CNFs) is beneficial to a rapid realization of their applications in energy storage field. Here, a series of one-dimensional C/MO x (M=Mn, Cu, Co) nanostructures are first prepared by a simple two-step process consisting of electrospinning and thermal treatment. The presence of low-valence MO x enhances the porosity and conductivity of nanocomposites to some extent through expanding graphitic domains or mixing metallic Cu into the CNF substrates. Next, the C/MO x frameworks are coated with MnO 2 nanosheets/nanowhiskers (C/MO x @MnO 2 ), during which process the low-valence MO x can partly reduce KMnO 4 so as to mitigate the consumption of CNFs. When used as active materials for supercapacitor electrodes, the obtained C/MO x @MnO 2 exhibit excellent electrochemical performances in comparison with the common CNFs@MnO 2 (CM) core-shell electrode due to the combination of desired functions of the individual components and the introduction of extra synergistic effect. It is believed that these results will provide an alternative way to further increase the capacitive properties of CNFs- or metal oxide-based nanomaterials and potentially stimulate the investigation on other kinds of C/MO x composite nanostructures for various applications. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Pressure-Dependent Light Emission of Charged and Neutral Excitons in Monolayer MoSe 2

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Xinpeng [State; Li, Fangfei [State; Lin, Jung-Fu [Department; Gong, Yuanbo [State; Huang, Xiaoli [State; Huang, Yanping [State; Han, Bo [State; Zhou, Qiang [State; Cui, Tian [State

    2017-07-19

    Tailoring the excitonic properties in two-dimensional monolayer transition metal dichalcogenides (TMDs) through strain engineering is an effective means to explore their potential applications in optoelectronics and nanoelectronics. Here we report pressure-tuned photon emission of trions and excitons in monolayer MoSe2 via a diamond anvil cell (DAC) through photoluminescence measurements and theoretical calculations. Under quasi-hydrostatic compressive strain, our results show neutral (X0) and charged (X–) exciton emission of monolayer MoSe2 can be effectively tuned by alcohol mixture vs inert argon pressure transmitting media (PTM). During this process, X– emission undergoes a continuous blue shift until reaching saturation, while X0 emission turns up splitting. The pressure-dependent charging effect observed in alcohol mixture PTM results in the increase of the X– exciton component and facilitates the pressure-tuned emission of X– excitons. This substantial tunability of X– and X0 excitons in MoSe2 can be extended to other 2D TMDs, which holds potential for developing strained and optical sensing devices.

  17. Nonlinear dynamics of trions under strong optical excitation in monolayer MoSe2.

    Science.gov (United States)

    Ye, Jialiang; Yan, Tengfei; Niu, Binghui; Li, Ying; Zhang, Xinhui

    2018-02-05

    By employing ultrafast transient reflection measurements based on two-color pump-probe spectroscopy, the population and valley polarization dynamics of trions in monolayer MoSe 2 were investigated at relatively high excitation densities under near-resonant excitation. Both the nonlinear dynamic photobleaching of the trion resonance and the redshift of the exciton resonance were found to be responsible for the excitation-energy- and density-dependent transient reflection change as a result of many-body interactions. Furthermore, from the polarization-resolved measurements, it was revealed that the initial fast population and polarization decay process upon strong photoexcitation observed for trions was determined by trion formation, transient phase-space filling and the short valley lifetime of excitons. The results provide a basic understanding of the nonlinear dynamics of population and valley depolarization of trions, as well as exciton-trion correlation in atomically thin MoSe 2 and other transition metal dichalcogenide materials.

  18. Lattice parameter values and phase transitions for the Cu2Cd1-zMn zGeSe4 and Cu2Cd1-zFe zGeSe4 alloys

    International Nuclear Information System (INIS)

    Quintero, E.; Tovar, R.; Quintero, M.; Delgado, G.E.; Morocoima, M.; Caldera, D.; Ruiz, J.; Mora, A.E.; Briceno, M.; Fernandez, J.L.

    2007-01-01

    X-ray powder diffraction measurements and differential thermal analysis (DTA) were made on polycrystalline samples of the Cu 2 Cd 1-z Mn z GeSe 4 and Cu 2 Cd 1-z Fe z GeSe 4 alloy systems. The diffraction patterns were used to show the equilibrium conditions and to derive lattice parameter values. The effect of the annealing temperature and cooling rate to room temperature are discussed. For the Cu 2 Cd 1-z Fe z GeSe 4 system, only two single solid phase fields, the tetragonal stannite α and the wurtz-stannite δ structures were found to occur in the diagram. For the Cu 2 Cd 1-z Mn z GeSe 4 system, in addition to the tetragonal stannite α and the wurtz-stannite δ phases, MnSe was found to exist in the diagram. The DTA experiments showed that the cooling curves for both systems exhibited effects of undercooling

  19. Structural study of CaMn_1_−_xMo_xO_3 (0.08 ≤ x ≤ 0.12) system by neutron powder diffraction

    International Nuclear Information System (INIS)

    Supelano, G.I.; Parra Vargas, C.A.; Barón-González, A.J.; Sarmiento Santos, A.; Frontera, C.

    2016-01-01

    Neutron powder diffraction experiments and magnetic measurements in polycrystalline CaMn_1_−_xMo_xO_3 (x = 0.08, 0.10, 0.12) point towards a possible charge and orbital order in this system. The analysis of structural and magnetic data show that the samples present structural phase transformation from Pnma to P2_1/m space group and the system has a C-type antiferromagnetic configuration at low temperature. A detailed analysis of the bond distances signals a small Jahn-Teller distortion of only one (x = 0.08) or of the two Mn ions (x = 0.10, 0.12). We identify the partially occupied e_g orbitals and this explains the C-type magnetic structure. - Highlights: • CaMn_1_−_xMo_xO_3 (x = 0.08, 0.10, 0.12) is investigated by neutron powder diffraction. • Analysis of individual Mn-O distances demonstrates the apparition of orbital order. • By symmetry analysis, we find that the low temperature magnetic structure is C-type. • Magnetic interactions foreseen by the orbital order explain the magnetic structure.

  20. Incorporation of Mn2+ into CdSe quantum dots by chemical bath co-deposition method for photovoltaic enhancement of quantum dot-sensitized solar cells.

    Science.gov (United States)

    Zhang, Chenguang; Liu, Shaowen; Liu, Xingwei; Deng, Fei; Xiong, Yan; Tsai, Fang-Chang

    2018-03-01

    A photoelectric conversion efficiency (PCE) of 4.9% was obtained under 100 mW cm -2 illumination by quantum-dot-sensitized solar cells (QDSSCs) using a CdS/Mn : CdSe sensitizer. CdS quantum dots (QDs) were deposited on a TiO 2 mesoporous oxide film by successive ionic layer absorption and reaction. Mn 2+ doping into CdSe QDs is an innovative and simple method-chemical bath co-deposition, that is, mixing the Mn ion source with CdSe precursor solution for Mn : CdSe QD deposition. Compared with the CdS/CdSe sensitizer without Mn 2+ incorporation, the PCE was increased from 3.4% to 4.9%. The effects of Mn 2+ doping on the chemical, physical and photovoltaic properties of the QDSSCs were investigated by energy dispersive spectrometry, absorption spectroscopy, photocurrent density-voltage characteristics and electrochemical impedance spectroscopy. Mn-doped CdSe QDs in QDSSCs can obtain superior light absorption, faster electron transport and slower charge recombination than CdSe QDs.

  1. Efficiency Enhanced Colloidal Mn-Doped Type II Core/Shell ZnSe/CdS Quantum Dot Sensitized Hybrid Solar Cells

    Directory of Open Access Journals (Sweden)

    A. Jamshidi

    2015-01-01

    Full Text Available Colloidal Mn-doped ZnSe/CdS core/shell quantum dots (QDs are synthesized for the first time and employed as a strategy to boost the power conversion efficiency of quantum dot sensitized solar cells. By using Mn-doping as a band gap engineering tool for core/shell QDs an effective improvement of absorption spectra could be obtained. The mid-states generated by a proper Mn content alleviate carrier separation and enhance the electron injection rate, thus facilitating electron transport to the TiO2 substrate. It is demonstrated that a device constructed with 0.25% Mn-doped ZnSe/CdS leads to an enhancement of the electron injection rate and power conversion efficiency by 4 times and 1.3, respectively.

  2. Recent Developments in Synthesis of xLi2MnO3 · (1 − x)LiMO2 (M = Ni, Co, Mn) Cathode Powders for High-Energy Lithium Rechargeable Batteries

    International Nuclear Information System (INIS)

    Doan, The Nam Long; Yoo, Kimoon; Hoang, Tuan K. A.; Chen, P.

    2014-01-01

    Lithium-rich layered powders, Li 2 MnO 3 -stabilized LiMO 2 (M = Ni, Co, Mn), are attractive cathode candidates for the next generations of high-energy lithium-ion batteries. However, most of the state-of-the-art preparation procedures are complicated and require multiple energy-intensive reaction steps. Thus, elucidating a low-cost synthetic protocol is important for the application of these materials in future lithium-ion batteries. Recent developments in the synthesis procedures of lithium-rich layered powders are discussed and future directions are pointed out in this review.

  3. Phase evolution during CuInSe{sub 2} electrodeposition on polycrystalline Mo

    Energy Technology Data Exchange (ETDEWEB)

    Saucedo, E., E-mail: edgardo.saucedo@hotmail.co [Institut de Recherche et Developement sur l' Energie Photovoltaique (IRDEP), 6 Quai Watier-BP 49, 78401 Chatou cedex (France); Ruiz, C.M.; Chassaing, E.; Jaime-Ferrer, J.S.; Grand, P.P.; Savidand, G.; Bermudez, V. [Institut de Recherche et Developement sur l' Energie Photovoltaique (IRDEP), 6 Quai Watier-BP 49, 78401 Chatou cedex (France)

    2010-05-03

    Using structural analyses means of ex-situ Raman spectroscopy and X-ray diffraction combined with electrical measurements, we study the phase evolution in the growth by electrodeposition technique of CuInSe{sub 2} on polycrystalline Mo. For this purpose the growth was stopped at different stages, and then the different layers were analysed. First growth steps seem to be controlled by the deposition of secondary phases, like elemental Se and Cu{sub 2}Se binary. After the deposition of approximately 300 nm of material, CuInSe{sub 2} ternary and ordered vacancy compounds start to adequately form. At a thickness close to 2000 nm, the formation of binary Cu{sub x}Se is observed, remaining up to the final growth process (4350 nm). All these results are compared with the kinetic model of the system under the consideration of the experimental composition evolution.

  4. Local moment formation and magnetic coupling of Mn dopants in Bi2Se3: A low-temperature ferromagnetic resonance study

    Science.gov (United States)

    Savchenko, D.; Tarasenko, R.; Vališka, M.; Kopeček, J.; Fekete, L.; Carva, K.; Holý, V.; Springholz, G.; Sechovský, V.; Honolka, J.

    2018-05-01

    We compare the magnetic and electronic configuration of single Mn atoms in molecular beam epitaxy (MBE) grown Bi2Se3 thin films, focusing on electron paramagnetic (ferromagnetic) resonance (EPR and FMR, respectively) and superconducting quantum interference device (SQUID) techniques. X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) reveal the expected increase of disorder with increasing concentration of magnetic guest atoms, however, Kikuchi patterns show that disorder consists majorly of μm-scale 60° twin domains in the hexagonal Bi2Se3 structure, which are promoted by the presence of single unclustered Mn impurities. Ferromagnetism below TC (5.4±0.3) K can be well described by critical scaling laws M (T) (1 - T /TC) β with a critical exponent β = (0.34 ± 0.2) , suggesting 3D Heisenberg class magnetism instead of e.g. 2D-type coupling between Mn-spins in van der Waals gap sites. From EPR hyperfine structure data we determine a Mn2+ (d5, S = 5/2) electronic configuration with a g-factor of 2.002 for -1/2 → +1/2 transitions. In addition, from the strong dependence of the low temperature FMR fields and linewidth on the field strength and orientation with respect to the Bi2Se3 (0001) plane, we derive magnetic anisotropy energies of up to K1 = -3720 erg/cm3 in MBE-grown Mn-doped Bi2Se3, reflecting the first order magneto-crystalline anisotropy of an in-plane magnetic easy plane in a hexagonal (0001) crystal symmetry. We observe an increase of K1 with increasing Mn concentration, which we interpret to be correlated to a Mn-induced in-plane lattice contraction. Across the ferromagnetic-paramagnetic transition the FMR intensity is suppressed and resonance fields converge the paramagnetic limit of Mn2+ (d5, S = 5/2).

  5. Improved photovoltaic performance and stability of quantum dot sensitized solar cells using Mn-ZnSe shell structure with enhanced light absorption and recombination control.

    Science.gov (United States)

    Gopi, Chandu V V M; Venkata-Haritha, M; Kim, Soo-Kyoung; Kim, Hee-Je

    2015-08-07

    To make quantum-dot-sensitized solar cells (QDSSCs) competitive, photovoltaic parameters comparable to those of other emerging solar cell technologies are necessary. In the present study, ZnSe was used as an alternative to ZnS, one of the most widely used passivation materials in QDSSCs. ZnSe was deposited on a TiO2-CdS-CdSe photoanode to form a core-shell structure, which was more efficient in terms of reducing the electron recombination in QDSSCs. The development of an efficient passivation layer is a requirement for preventing recombination processes in order to attain high-performance and stable QDSSCs. A layer of inorganic Mn-ZnSe was applied to a QD-sensitized photoanode to enhance the adsorption and strongly inhibit interfacial recombination processes in QDSSCs, which greatly improved the power conversion efficiency. Impedance spectroscopy revealed that the combined Mn doping with ZnSe treatment reduces interfacial recombination and increases charge collection efficiency compared with Mn-ZnS, ZnS, and ZnSe. A solar cell based on the CdS-CdSe-Mn-ZnSe photoanode yielded excellent performance with a solar power conversion efficiency of 5.67%, Voc of 0.584 V, and Jsc of 17.59 mA cm(-2). Enhanced electron transport and reduced electron recombination are responsible for the improved Jsc and Voc of the QDSSCs. The effective electron lifetime of the device with Mn-ZnSe was higher than those with Mn-ZnS, ZnSe, and ZnS, leading to more efficient electron-hole separation and slower electron recombination.

  6. X-ray magnetic spectroscopy of MBE-grown Mn-doped Bi2Se3 thin films

    Directory of Open Access Journals (Sweden)

    L. J. Collins-McIntyre

    2014-12-01

    Full Text Available We report the growth of Mn-doped Bi2Se3 thin films by molecular beam epitaxy (MBE, investigated by x-ray diffraction (XRD, atomic force microscopy (AFM, SQUID magnetometry and x-ray magnetic circular dichroism (XMCD. Epitaxial films were deposited on c-plane sapphire substrates by co-evaporation. The films exhibit a spiral growth mechanism typical of this material class, as revealed by AFM. The XRD measurements demonstrate a good crystalline structure which is retained upon doping up to ∼7.5 atomic-% Mn, determined by Rutherford backscattering spectrometry (RBS, and show no evidence of the formation of parasitic phases. However an increasing interstitial incorporation of Mn is observed with increasing doping concentration. A magnetic moment of 5.1 μB/Mn is obtained from bulk-sensitive SQUID measurements, and a much lower moment of 1.6 μB/Mn from surface-sensitive XMCD. At ∼2.5 K, XMCD at the Mn L2,3 edge, reveals short-range magnetic order in the films and indicates ferromagnetic order below 1.5 K.

  7. Bioaccumulation of heavy metals and metalloids in luffa (luffa cylindrica l.) irrigated with domestic wastewater in jhang, pakistan: a prospect for human nutrition

    International Nuclear Information System (INIS)

    Khani, Z.I.; Ahmad, K.

    2015-01-01

    In the present study, 12 heavy metals (Cr, Mn, Ni, Cd, Co, Cu, Pb, Zn, Fe, Se, As, and Mo) were assessed in a potential vegetable Luffa cylindrica. The vegetable was collected randomly from two different sites located at Jhang, Punjab Pakistan. The analyses of variance of data collected from soil showed non-significant effect on Se, Zn, As, Cr, Ni, Mo and Pb while significant effect on Fe, Co, Mn, Cu and Cd metals. Concentrations of all 12 heavy metals in the soil samples were low at sampling site-I as compared to those at site-II except Ni. These concentrations were found below the safe limits except that of Cd. At site-I, the concentrations recorded for different heavy metals were: As > Fe > Pb > Mn > Cd > Co > Cu > Mo > Zn > Ni > Se > Cr while at site-II were: As > Fe > Mn > Pb > Co > Cd > Cu > Mo > Zn > Ni > Se > Cr. Enrichment co-efficient of Cr was higher which showed that root of luffa plant accumulated more Cr concentration from the contaminated soil. The order of enrichment co-efficient was recorded at site-I as: Cr > Zn > Mn > Cu > Fe > Ni > Mo > Pb > As > Se > Co > Cd, and at site-II Cr > Zn > Mn > Ni > Cu > Fe > Mo > Pb > Se > As > Co > Cd. The transfer co-efficient of Mn was higher which indicates that more contents of Mn were transferred from roots to upper edible part. The order of transfer co-efficient at site-I was: Ni > Se > Mo > Cr > Zn > Fe > Mn > Cd > Pb > As > Cu > Co and at site-II was Mn > Zn > As > Fe > Pb > Se > Cd > Co > Mo > Cu > Ni > Cr. Correlation analysis showed that Mn, Se, Co, Cd, Ni, Mo and Pb had positive non-significant correlation, whereas a negative and non-significant correlation for Zn, As, Fe and Cr. The order of pollution load index at site-I was Cd > Mo > Se > Pb > Cu > Co > As > Fe > Mn > Ni > Zn > Cr and at site-II: Cd > Mo > Se > Pb > Cu > Co > As > Fe > Mn > Ni > Zn > Cr. Overall, at both sites, lowest concentration of Cr and highest of As were observed which need substantial awareness. Health risk index depends on

  8. Crystal structure of the new diamond-like semiconductor CuMn2InSe4

    Indian Academy of Sciences (India)

    Abstract. The crystal structure of the semiconductor compound CuMn2InSe4 was analysed using X-ray powder ... properties arising from the presence of magnetic ions in the ... by SEM technique, using a Hitachi S2500 microscope equip-.

  9. Intergranular fracture stress and phosphorus grain boundary segregation of a Mn-Ni-Mo steel

    International Nuclear Information System (INIS)

    Naudin, C.; Frund, J.M.; Pineau, A.

    1999-01-01

    Nuclear Reactor Pressure Vessel (RPV) steel A508 class 3 which is a low alloyed steel is not usually sensitive to reversible temper embrittlement when properly heat treated. However heterogeneous zones may be present in particular near the inner side of the vessel. These zones result from the segregation of the alloying elements (C, Mn, Ni, Mo) and impurities (S, P) taking place during solidification of the material. They are called segregated zones (or ghost lines). They can reach 2 mm thick along the radius and 30 mm long through the circumferential direction. Their susceptibility to reversible temper embrittlement is mainly due to grain boundary phosphorus segregation triggering brittle intergranular fracture when the material is tested at low temperature. In this material like in other steels the influence of some other alloying elements (Mo, Mn...) is clearly significant and should also be taken into account. But phosphorus effect has proved to be predominant. The aim of the present study is therefore to find out a quantitative relationship between grain boundary phosphorus segregation and critical intergranular fracture stress. A synthetic steel with a chemical composition representative of an average segregated zone was prepared for the present study. A number of heat treatments were applied to reach different embrittlement conditions. Then brittle fracture properties were obtained by performing cryogenic fracture tests on notched tensile specimens while the corresponding grain boundary phosphorus levels were measured by Auger electron spectroscopy. Systematic fractographic observations were carried out. Moreover an attempt to determine the influence of temperature on the critical intergranular fracture stress was made

  10. Manifested luminescence and magnetic responses of stoichiometry dependent Cd{sub 1− x}Mn{sub x}Se quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Sarma, Runjun; Deka, Geetamoni; Mohanta, Dambarudhar, E-mail: best@tezu.ernet.in

    2015-02-15

    Highlights: • Thio-glycolic acid (TGA) coated Cd{sub 1−x}Mn{sub x}Se quantum dots have been prepared with varying x • Formation of QD heterostructure can be expected at a nonzero, but higher value of x. • The deep defect related emission can be attributed to V{sub Cd}–V{sub Se} di-vacancies, which is dominant for smaller values of x. • An appreciable charge transfer between Mn{sup 2+} ions and capping agent TGA is anticipated. - Abstract: We report on stoichiometry dependent manifested physical properties of thioglycolic acid (TGA) coated Cd{sub 1− x}Mn{sub x}Se QDs. While possessing a wurtzite phase, with increasing x, the QDs exhibited a notable blue-shifting of the onset of absorption. Attributed to V{sub Cd}–V{sub Se} di-vacancies, the QDs describe an intense deep-defect related emission response at smaller values of x (=0 to 0.3). Due to the facilitation of magnetic Mn{sup 2+} ion migration from the core to the QD surfaces, {sup 4}T{sub 1}–{sup 6}A{sub 1} transition based Mn{sup 2+} orange emission get suppressed at a higher x (=0.6 to 1). While the FT-IR spectra of the alloyed QDs display characteristic Mn–OH stretching mode at ∼644 cm{sup −1}, the peak located at ∼703 cm{sup −1} is assigned to Cd-Se bending. Furthermore, the QDs with a low x (=0.3), exhibit paramagnetic characteristics owing to the presence of uncorrelated, isolated Mn{sup 2+} spins. The collective luminescence and magnetic features would find immense scope in bio-labeling and imaging applications, apart from solid state luminescent components.

  11. Electrical control of truly two-dimensional neutral and charged excitons in monolayer MoSe2

    Science.gov (United States)

    Ross, Jason; Wu, Sanfeng; Yu, Hongyi; Ghimire, Nirmal; Jones, Aaron; Aivazian, Grant; Yan, Jiaqiang; Mandrus, David; Xiao, Di; Xiao, Di; Xu, Xiaodong

    2013-03-01

    Monolayer transition metal dichalcogenides (TMDs) have emerged as ideal 2D semiconductors with valley and spin polarized excitations expected to enable true valley-tronics. Here we investigate MoSe2, a TMD which has yet to be characterized in the monolayer limit. Specifically, we examine excitons and trions (their singly charged counterparts) in the ultimate 2D limit. Utilizing high quality exfoliated MoSe2 monolayers, we report the observation and electrostatic tunability of positively charged (X +) , neutral (Xo), and negatively charged (X-) excitons via photoluminescence in FETs. The trion charging energy is large (30 meV), enhanced by strong confinement and heavy effective masses, while the linewidth is narrow (5 meV) at temperatures below 55 K. This is greater spectral contrast than in any known quasi-2D system. Further, the charging energies for X + and X- to are nearly identical implying the same effective mass for electrons and holes, which supports their recent description as massive Dirac fermions. This work demonstrates that monolayer MoSe2 is an ultimate 2D semiconductor opening the door for the investigation of truly 2D exciton physics while laying the ground work necessary to begin valley-spin polarization studies. Support: US DoE, BES, Division of MSE. HY and WY supported by Research Grant Council of Hong Kong

  12. Electrical transport properties study of Mo{sub 0.6}W{sub 0.4}Se{sub 2} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Chaki, Sunil; Deshpande, M. P.; Tailor, J. P.; Chaudhary, M. D.; Sakaria, Pallavi N. [Department of Physics, Sardar Patel University, Vallabh Vidyanagar, Gujarat-388120 (India)

    2012-06-05

    The mixed transition metal dichalcogenide single crystals Mo{sub 0.6}W{sub 0.4}Se{sub 2} were characterized employing EDAX (Energy Dispersive Analysis of X-ray), (XRD) X-ray diffraction, SEM (Scanning Electron Microscope) and UV-Vis-NIR spectroscopy techniques. The electrical transport properties of as-grown Mo{sub 0.6}W{sub 0.4}Se{sub 2} single crystals were studied by two probe d. c. resistivity, Hall Effect and thermoelectric power measurement set-up. The obtained results are discussed in details.

  13. Sr doped BiMO{sub 3} (M = Mn, Fe, Y) perovskites: Structure correlated thermal and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Samita, E-mail: samitasthakur@gmail.com [School of Physics and Materials Science, Thapar University, Patiala 147004 (India); School of Basic Sciences, Arni University, Kathgarh (India); Singh, K.; Pandey, O.P. [School of Physics and Materials Science, Thapar University, Patiala 147004 (India)

    2017-02-01

    Sr{sup 2+} substituted BiMnO{sub 3−δ} (BSM), BiFeO{sub 3−δ} (BSF) and BiYO{sub 3−δ} (BSY) perovskites structured samples have been investigated for their structural, thermal and electrical properties. These samples are characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), iodometric titration, Raman spectroscopy, thermogravimetric analysis (TGA) and conductivity. Rietveld refinement confirms that BSY sample has cubic (Fm-3m) symmetry with limited solid solubility of Sr{sup 2+} as compared to tetragonal symmetry (p4mm) of BSM and BSF samples. X-ray photoelectron spectroscopy study confirms the presence of Mn{sup 4+} and Fe{sup 4+} content in BSM and BSF samples. The amount of Mn{sup 3+}, Fe{sup 4+} and oxygen vacancies in these systems are calculated by iodometric titration. The highest oxygen vacancies are found in BSF sample. The BSM system exhibit the highest conductivity followed by BSF and BSY samples due to the presence of Mn{sup 4+} content and moderate oxygen vacancies in this particular sample. - Highlights: • (BiSr)MO{sub 3} (M = Mn, Fe, Y) was synthesized by solid state reaction method. • The B-site cation highly affect the generation of defects in perovskites. • The structural and electrical properties strongly depend upon the B-site cation.

  14. Ambipolar transport in CVD grown MoSe2 monolayer using an ionic liquid gel gate dielectric

    Directory of Open Access Journals (Sweden)

    Deliris N. Ortiz

    2018-03-01

    Full Text Available CVD grown MoSe2 monolayers were electrically characterized at room temperature in a field effect transistor (FET configuration using an ionic liquid (IL as the gate dielectric. During the growth, instead of using MoO3 powder, ammonium heptamolybdate was used for better Mo control of the source and sodium cholate added for lager MoSe2 growth areas. In addition, a high specific capacitance (∼7 μF/cm2 IL was used as the gate dielectric to significantly reduce the operating voltage. The device exhibited ambipolar charge transport at low voltages with enhanced parameters during n- and p-FET operation. IL gating thins the Schottky barrier at the metal/semiconductor interface permitting efficient charge injection into the channel and reduces the effects of contact resistance on device performance. The large specific capacitance of the IL was also responsible for a much higher induced charge density compared to the standard SiO2 dielectric. The device was successfully tested as an inverter with a gain of ∼2. Using a common metal for contacts simplifies fabrication of this ambipolar device, and the possibility of radiative recombination of holes and electrons could further extend its use in low power optoelectronic applications.

  15. Effect of Si and Mn additions on ferrite and austenite phase fractions in 25Cr-7Ni-1.5Mo-3W base super duplex stainless steels

    International Nuclear Information System (INIS)

    Jeong, S.W.; Lee, Z.-H.; Lee, H.M.

    2000-01-01

    The effect of heat treatment and Si and Mn additions on the ferrite and austenite phase fractions of the super duplex stainless steel (SDSS), Fe-25Cr-7Ni-1.5Mo-3W-Si-Mn-0.25N (numbers are all in wt.% unless specified otherwise), was investigated. The thermodynamic calculations of phase equilibria and phase fractions were performed using the Thermo-Calc program. Based on the calculated results, specific compositions of Si and Mn were selected and alloys with these compositions were analysed by Feritscope, X-ray diffractometry and scanning electron microscopy. The calculated phase fractions and experimentally analysed ones were compared and there was a good agreement between calculations and measurements. The optimum heat treatment condition for Fe-25Cr-7Ni-1.5Mo-3W-0.5Si-0.5Mn-0.25N is to hold at 1050 to 1100 C for 2 h in considering the ferrite to austenite ratio of 50:50 and to avoid second phase precipitation such as the σ phase. It was suggested that an excessive addition of more than 0.8Si and 1.0Mn may induce the σ phase precipitation. (orig.)

  16. Improved cycling performance of Li{sub 2}MoO{sub 4}-inlaid LiNi{sub 0.5}Co{sub 0.2}Mn{sub 0.3}O{sub 2} cathode materials for lithium-ion battery under high cutoff voltage

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Manfang; Hu, Guorong; Liang, Longwei; Peng, Zhongdong; Du, Ke; Cao, Yanbing, E-mail: cybcsu@csu.edu.cn

    2016-07-15

    Uniform spherical xLi{sub 2}MoO{sub 4}-inlaid LiNi{sub 0.5}Co{sub 0.2}Mn{sub 0.3}O{sub 2} materials were successfully prepared through a solid state synthesis. To investigate the material characterization and electrochemical performance after Li{sub 2}MoO{sub 4} modification, X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) mapping, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and electrochemical tests were applied. The results of the XRD, Rietveld refinement, SEM and EDS analyses showed that a Mo atom may be incorporated into the crystal lattice of the layer structure. Moreover, the presence of Li{sub 2}MoO{sub 4} on the LiNi{sub 0.5}Co{sub 0.2}Mn{sub 0.3}O{sub 2} surface was observed. The thickness of the Li{sub 2}MoO{sub 4} coating layer on the xLi{sub 2}MoO{sub 4}-inlaid LiNi{sub 0.5}Co{sub 0.2}Mn{sub 0.3}O{sub 2} material (x = 0.02) was approximately 25 nm. Similarly, XPS was performed to determine the effect of Li{sub 2}MoO{sub 4} modification, confirming the presence of Li{sub 2}MoO{sub 4}. The xLi{sub 2}MoO{sub 4}-inlaid (x = 0.02) LiNi{sub 0.5}Co{sub 0.2}Mn{sub 0.3}O{sub 2} materials exhibited a retention capacity 83.5% higher than that of the bare material (40.9%) after 200 cycles at 0.5 C between 3.0 and 4.4 V, and it also exhibited the best electrochemical properties at a cutoff voltage of 4.5 V. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) confirmed that the modification of Li{sub 2}MoO{sub 4} plays an important role in improving the electrochemical performance of pristine LiNi{sub 0.5}Co{sub 0.2}Mn{sub 0.3}O{sub 2}. - Highlights: • Electrochemical performance of LiNi{sub 0.5}Co{sub 0.2}Mn{sub 0.3}O{sub 2} is improved by Li{sub 2}MoO{sub 4} modification. • Li{sub 2}MoO{sub 4} modification can make the structure of the bare material stable. • Li{sub 2}MoO{sub 4}-inlaid Li[Ni{sub 0.5}Co{sub 0.2}Mn{sub 0.3}]O{sub 2

  17. Surface composition of Cd{sub 1–x}Fe(Mn){sub x}Te{sub 1–y}Se{sub y} systems exposed to air

    Energy Technology Data Exchange (ETDEWEB)

    Bundaleski, Nenad [University of Belgrade–Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia); Universidade Nova de Lisboa–Faculdade de Ciências e Tecnologia, Quinta da Torre, 2829–516 Caparica (Portugal); Radisavljević, Ivana, E-mail: iva@vin.bg.ac.rs [University of Belgrade–Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia); Trigueiro, João [Universidade Nova de Lisboa–Faculdade de Ciências e Tecnologia, Quinta da Torre, 2829–516 Caparica (Portugal); Tolstogouzov, Alexander [Universidade Nova de Lisboa–Faculdade de Ciências e Tecnologia, Quinta da Torre, 2829–516 Caparica (Portugal); Ryazan State Radio Engineering University, Gagarin 59/1, 390005 Ryazan (Russian Federation); Rakočević, Zlatko; Medić, Mirjana [University of Belgrade–Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia); Teodoro, Orlando M.N.D. [Universidade Nova de Lisboa–Faculdade de Ciências e Tecnologia, Quinta da Torre, 2829–516 Caparica (Portugal); Romčević, Nebojša [University of Belgrade–Institute of Physics, Pregrevica 118, 11000 Belgrade (Serbia); Ivanović, Nenad [University of Belgrade–Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia)

    2017-03-01

    Using X–ray induced Photoelectron Spectroscopy, Time–of–Flight Secondary Ion Mass Spectrometry and Atomic Force Microscopy we have investigated elemental composition, structure and oxidation process taking place at the surfaces of polycrystalline Cd{sub 0.99}Fe{sub 0.01}Te{sub 0.97}Se{sub 0.03} and Cd{sub 0.95}Mn{sub 0.05}Te{sub 0.97}Se{sub 0.03} systems stored in ambient conditions. The surface oxidation destroys the native CdTe matrix and provokes substantial atomic rearrangement in the first few atomic layers. The near–surface region of both systems is enriched in Cd and to some extent Te–deficient, but the surface structure, morphology and the native oxide composition are all found to be considerably different. In Cd{sub 0.99}Fe{sub 0.01}Te{sub 0.97}Se{sub 0.03} system both Fe and Se dopants diffuse into the bulk and oxidation of its surface results in formation of a thin CdTeO{sub 3} layer which covers the CdTe matrix. In Cd{sub 0.95}Mn{sub 0.05}Te{sub 0.97}Se{sub 0.03} system oxygen–rich atmosphere triggers Mn and Se out–diffusion and the nonuniform oxide layer predominantly consists of MnO and a small amount of Te–oxide which both lay underneath a thin layer of metallic Cd segregated at the top of the surface. - Highlights: • Nature of the CdFe(Mn)TeSe surfaces exposed to air is substantially different. • Near–surface region is enriched in Cd and to some extent Te–deficient. • Presence of Mn drastically changes the surface oxidation conditions. • The surface oxidation in ambient conditions undergoes different mechanisms. • Oxygen triggers Mn out–diffusion, while Fe diffuses into the bulk.

  18. Thermoelectric properties of M{sub 2}Mo{sub 6}Se{sub 6} (M =Tl,In)

    Energy Technology Data Exchange (ETDEWEB)

    Verebelyi, D T; Payne, J E; Tessema, G X; Mengistu, E

    1997-07-01

    The authors have measured the thermal conductivity of Tl{sub 2}Mo{sub 6}Se{sub 6}, a quasi-one dimensional conductor which belongs to the family of M{sub 2}Mo{sub 6}X{sub 6} linear chain compounds. Using these results and the measurements of the Seebeck coefficient and the electrical conductivity the authors estimate the dimensionless figure of merit to be of the order of 0.08. This result suggest that this compound and other related compounds are good potential TE.

  19. Influence of High Mn-Cu-Mo on Microstructure and Fatigue characteristics of Austempered Ductile Iron

    Science.gov (United States)

    Banavasi Shashidhar, M.; Ravishankar, K. S.; Naik Padmayya, S.

    2018-03-01

    The impacts of high Mn content on microstructure and fatigue characteristics of ADI at 300, 350 and 400 °C for 120 min have been examined. Optical microscopy images reveals bainite morphology only at 300°C. Higher Mn contents hinders bainite transformation in the locales of Mn and Mo segregation, where in stage II reaction initiates near the graphite nodules before stage I reaction ends away from the nodules which creates more unreacted austenite volume after cooling forming martensite around the periphery creating austenite-martensite zone at 350 °C and tremendously articulated at 400°C. Feathery ferrite laths, stable retained austenite and uniform density hardness in the matrix, promotes higher toughness and fatigue properties (250 MPa @ 106 cycles) at 300 °C. Presence of stage II carbides in the eutectic cell and austenite-martensite zone in the intercellular regions, due to their embrittlement in the matrix, makes easy crack path for initiation and propagation deteriorating properties at 350°C and above. SEM images of fatigue fractured surface revealed that at 300°C, showed a regular crack interconnecting graphite nodule, fatigue striation and quazi-cleavage fracture mode, and at 350 & 400°C reveals the carbide, austenite-martensite and porosity/defect final fracture region.

  20. Ab initio, mean field theory and series expansions calculations study of electronic and magnetic properties of antiferromagnetic MnSe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, BP. 63, 46000 Safi (Morocco); LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France); Hamedoun, M. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Benyoussef, A. [LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); Mounkachi, O.; El Moussaoui, H. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco)

    2014-06-01

    Self-consistent ab initio calculations, based on DFT (Density Functional Theory) approach and using FLAPW (Full potential Linear Augmented Plane Wave) method, are performed to investigate both electronic and magnetic properties of the MnSe lattice. Polarized spin and spin–orbit coupling are included in calculations within the framework of the antiferromagnetic state between two adjacent Mn lattices. Magnetic moments considered to lie along (001) axes are computed. Obtained data from ab initio calculations are used as input for the high temperature series expansions (HTSEs) calculations to compute other magnetic parameters. The zero-field high temperature static susceptibility series of the spin −4.28 nearest-neighbor Ising model on face centered cubic (fcc) and lattices is thoroughly analyzed by means of a power series coherent anomaly method (CAM). The exchange interaction between the magnetic atoms and the Néel temperature are deduced using the mean filed and HTSEs theories. - Highlights: • Ab initio calculations are used to investigate both electronic and magnetic properties of the MnSe alloys. • Obtained data from ab initio calculations are used as input for the HTSEs. • The Néel temperature is obtained for MnSe alloys.

  1. Measurement of the forward-backward asymmetry in top quark-antiquark production in pp<mo accent='true' stretchy='false'>¯mo> collisions using the lepton<mo mathvariant='bold'>+mo>jets channel

    Energy Technology Data Exchange (ETDEWEB)

    Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Agnew, J. P.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Askew, A.; Atkins, S.; Augsten, K.; Avila, C.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, P.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Bean, A.; Begalli, M.; Bellantoni, L.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besançon, M.; Beuselinck, R.; Bhat, P. C.; Bhatia, S.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; Boos, E. E.; Borissov, G.; Borysova, M.; Brandt, A.; Brandt, O.; Brock, R.; Bross, A.; Brown, D.; Bu, X. B.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Buszello, C. P.; Camacho-Pérez, E.; Casey, B. C. K.; Castilla-Valdez, H.; Caughron, S.; Chakrabarti, S.; Chan, K. M.; Chandra, A.; Chapon, E.; Chen, G.; Cho, S. W.; Choi, S.; Choudhary, B.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M. -C.; Cutts, D.; Das, A.; Davies, G.; de Jong, S. J.; De La Cruz-Burelo, E.; Déliot, F.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Deterre, C.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Ding, P. F.; Dominguez, A.; Dubey, A.; Dudko, L. V.; Duperrin, A.; Dutt, S.; Eads, M.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Enari, Y.; Evans, H.; Evdokimov, V. N.; Falkowski, A.; Fauré, A.; Feng, L.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fortner, M.; Fox, H.; Fuess, S.; Garbincius, P. H.; Garcia-Bellido, A.; García-González, J. A.; Gavrilov, V.; Geng, W.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Gogota, O.; Golovanov, G.; Grannis, P. D.; Greder, S.; Greenlee, H.; Grenier, G.; Gris, Ph.; Grivaz, J. -F.; Grohsjean, A.; Grünendahl, S.; Grünewald, M. W.; Guillemin, T.; Gutierrez, G.; Gutierrez, P.; Haley, J.; Han, L.; Harder, K.; Harel, A.; Hauptman, J. M.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hoang, T.; Hobbs, J. D.; Hoeneisen, B.; Hogan, J.; Hohlfeld, M.; Holzbauer, J. L.; Howley, I.; Hubacek, Z.; Hynek, V.; Iashvili, I.; Ilchenko, Y.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffré, M.; Jayasinghe, A.; Jeong, M. S.; Jesik, R.; Jiang, P.; Johns, K.; Johnson, E.; Johnson, M.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Jung, A. W.; Juste, A.; Kajfasz, E.; Karmanov, D.; Katsanos, I.; Kehoe, R.; Kermiche, S.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Kiselevich, I.; Kohli, J. M.; Kozelov, A. V.; Kraus, J.; Kumar, A.; Kupco, A.; Kurča, T.; Kuzmin, V. A.; Lammers, S.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lei, X.; Lellouch, J.; Li, D.; Li, H.; Li, L.; Li, Q. Z.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, H.; Liu, Y.; Lobodenko, A.; Lokajicek, M.; Lopes de Sa, R.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Madar, R.; Magaña-Villalba, R.; Malik, S.; Malyshev, V. L.; Mansour, J.; Martínez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; Meyer, A.; Meyer, J.; Miconi, F.; Mondal, N. K.; Mulhearn, M.; Nagy, E.; Narain, M.; Nayyar, R.; Neal, H. A.; Negret, J. P.; Neustroev, P.; Nguyen, H. T.; Nunnemann, T.; Orbaker, D.; Orduna, J.; Osman, N.; Osta, J.; Pal, A.; Parashar, N.; Parihar, V.; Park, S. K.; Partridge, R.; Parua, N.; Patwa, A.; Penning, B.; Perfilov, M.; Peters, Y.; Petridis, K.; Petrillo, G.; Pétroff, P.; Pleier, M. -A.; Podstavkov, V. M.; Popov, A. V.; Prewitt, M.; Price, D.; Prokopenko, N.; Qian, J.; Quadt, A.; Quinn, B.; Ratoff, P. N.; Razumov, I.; Ripp-Baudot, I.; Rizatdinova, F.; Rominsky, M.; Ross, A.; Royon, C.; Rubinov, P.; Ruchti, R.; Sajot, G.; Sánchez-Hernández, A.; Sanders, M. P.; Santos, A. S.; Savage, G.; Savitskyi, M.; Sawyer, L.; Scanlon, T.; Schamberger, R. D.; Scheglov, Y.; Schellman, H.; Schwanenberger, C.; Schwienhorst, R.; Sekaric, J.; Severini, H.; Shabalina, E.; Shary, V.; Shaw, S.; Shchukin, A. A.; Simak, V.; Skubic, P.; Slattery, P.; Smirnov, D.; Snow, G. R.; Snow, J.; Snyder, S.; Söldner-Rembold, S.; Sonnenschein, L.; Soustruznik, K.; Stark, J.; Stoyanova, D. A.; Strauss, M.; Suter, L.; Svoisky, P.; Titov, M.; Tokmenin, V. V.; Tsai, Y. -T.; Tsybychev, D.; Tuchming, B.; Tully, C.; Uvarov, L.; Uvarov, S.; Uzunyan, S.; Van Kooten, R.; van Leeuwen, W. M.; Varelas, N.; Varnes, E. W.; Vasilyev, I. A.; Verkheev, A. Y.; Vertogradov, L. S.; Verzocchi, M.; Vesterinen, M.; Vilanova, D.; Vokac, P.; Wahl, H. D.; Wang, M. H. L. S.; Warchol, J.; Watts, G.; Wayne, M.; Weichert, J.; Welty-Rieger, L.; Williams, M. R. J.; Wilson, G. W.; Wobisch, M.; Wood, D. R.; Wyatt, T. R.; Xie, Y.; Yamada, R.; Yang, S.; Yasuda, T.; Yatsunenko, Y. A.; Ye, W.; Ye, Z.; Yin, H.; Yip, K.; Youn, S. W.; Yu, J. M.; Zennamo, J.; Zhao, T. G.; Zhou, B.; Zhu, J.; Zielinski, M.; Zieminska, D.; Zivkovic, L.

    2014-10-01

    We present a measurement of the forward–backward asymmetry in top quark–antiquark production using the full Tevatron Run II data set collected by the D0 experiment at Fermilab. The measurement is performed in leptonmo>+>jets final states using a new kinematic fitting algorithm for events with four or more jets and a new partial reconstruction algorithm for events with only three jets. Corrected for detector acceptance and resolution effects, the asymmetry is evaluated to be AFBmo>= stretchy="false">(mo>>10.6mn>±>3.0mn> stretchy="false">)mo>%>. Results are consistent with the standard model predictions which range from 5.0% to 8.8%. We also present the dependence of the asymmetry on the invariant mass of the top quark–antiquark system and the difference in rapidities of the top quark and antiquark.

  2. Designing and controlling the microstructure of 37MnNiMo6-4-3 hypoeutectoid steel after continuous cooling

    OpenAIRE

    E. Rożniata

    2013-01-01

    Purpose: Present work corresponds to the research on the kinetic of phase transformation of undercooled austenite of 37MnNiMo6-4-3 hypoeutctoid steel. The kinetic of phase transformation of under cooled austenite of investigated alloy was presented on CCT diagram (continuous cooling transformation). Also the methodology of a dilatometric samples preparation and the method of the critical points determination were described.Design/methodology/approach: The austenitising temperature was defined...

  3. Discrete quantum dot like emitters in monolayer MoSe{sub 2}: Spatial mapping, magneto-optics, and charge tuning

    Energy Technology Data Exchange (ETDEWEB)

    Branny, Artur; Kumar, Santosh; Gerardot, Brian D., E-mail: b.d.gerardot@hw.ac.uk [Institute of Photonics and Quantum Sciences, SUPA, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Wang, Gang; Robert, Cedric; Lassagne, Benjamin; Marie, Xavier; Urbaszek, Bernhard, E-mail: urbaszek@insa-toulouse.fr [Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Av. Rangueil, 31077 Toulouse (France)

    2016-04-04

    Transition metal dichalcogenide monolayers such as MoSe{sub 2}, MoS{sub 2}, and WSe{sub 2} are direct bandgap semiconductors with original optoelectronic and spin-valley properties. Here we report on spectrally sharp, spatially localized emission in monolayer MoSe{sub 2}. We find this quantum dot-like emission in samples exfoliated onto gold substrates and also suspended flakes. Spatial mapping shows a correlation between the location of emitters and the existence of wrinkles (strained regions) in the flake. We tune the emission properties in magnetic and electric fields applied perpendicular to the monolayer plane. We extract an exciton g-factor of the discrete emitters close to −4, as for 2D excitons in this material. In a charge tunable sample, we record discrete jumps on the meV scale as charges are added to the emitter when changing the applied voltage.

  4. The double beta decay spectra of 82Se, 100Mo, and 150Nd

    International Nuclear Information System (INIS)

    Nelson, M.A.; Moe, M.K.; Vient, M.A.; Elliott, S.R.

    1992-01-01

    The double beta decay electron energy spectra of 82 Se, 100 Mo, and 150 Nd have been measured with a time projection chamber, and departures from the expected two-neutrino spectral shapes have been observed. Efforts to reduce possible background contamination have been made, and tests are now being done in an effort to determine whether the anomalous signals are real effects, or simply experimental artifacts

  5. Optical absorption and Faraday rotation in spin doped Cd1-xHgxSe : Mn crystals

    NARCIS (Netherlands)

    Savchuk, AI; Paranchich, SY; Paranchich, LD; Romanyuk, OS; Andriychuk, MD; Nikitin, PI; Tomlinson, RD; Hill, AE; Pilkington, RD

    1998-01-01

    Optical absorption spectra and the Faraday effect in crystals of Cd1-xHgxSe : Mn have been studied. The studied samples have been characterized abrupt absorption edge and transparency region with high transmission coefficient. The measured values of Verdet constant were considerably larger than in

  6. Ab-initio study of superconducting state in intercalated MoSe2 and WSe2 bilayers

    Science.gov (United States)

    Szcześniak, R.; Durajski, A. P.; Jarosik, M. W.

    2018-05-01

    A two-dimensional systems have attracted significant interest due to their outstanding physical, chemical and optoelectronic properties. This paper focuses on the detailed investigations of the electronic, phononic and superconducting properties of transition-metal dichalcogenide bilayers MSe 2 (M = Mo, W) intercalated by calcium atoms. The first-principles calculations show that (MoSe2)2Ca and (WSe2)2Ca systems exhibit metallic behavior and weak phonon-mediated superconductivity with low critical temperature of 0.51 and 0.30 K, respectively. These results confirm other theoretical predictions and suggest that the investigated materials cannot be a good candidates for a nanoscale superconductors.

  7. Synthesis and magnetic structure of the layered manganese oxide selenide Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Blandy, Jack N. [Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom); Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Boskovic, Jelena C. [Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom); Clarke, Simon J., E-mail: simon.clarke@chem.ox.ac.uk [Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom)

    2017-01-15

    The synthesis of a high-purity sample of the layered oxide selenide Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} is reported. At ambient temperature it crystallises in the space group I4/mmm with two formula units in the unit cell and lattice parameters a=4.08771(1) Å, c=19.13087(8) Å. The compound displays mixed-valent manganese in a formal oxidation state close to +2.5 and powder neutron diffraction measurements reveal that below the Néel temperature of 63(1) K this results in an antiferromagnetic structure which may be described as A-type, modelled in the magnetic space group P{sub I}4/mnc (128.410 in the Belov, Neronova and Smirnova (BNS) scheme) in which localised Mn moments of 3.99(2) μ{sub B} are arranged in ferromagnetic layers which are coupled antiferromagnetically. In contrast to the isostructural compound Sr{sub 2}MnO{sub 2}Cu{sub 1.5}S{sub 2}, Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} does not display long range ordering of coinage metal ions and vacancies, nor may significant amounts of the coinage metal readily be deintercalated using soft chemical methods. - Graphical abstract: Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} containing mixed valent Mn ions undergoes magnetic ordering with ferromagnetic coupling within MnO{sub 2} sheets and antiferromagnetic coupling between MnO{sub 2} sheets. - Highlights: • High purity sample of Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} obtained. • Magnetic structure determined. • Compared with related mixed-valent manganite oxide chalcogenides.

  8. Structural study of CaMn{sub 1−x}Mo{sub x}O{sub 3} (0.08 ≤ x ≤ 0.12) system by neutron powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Supelano, G.I., E-mail: ivan.supelano@uptc.edu.co [Grupo Física de Materiales, Escuela de Física, Universidad Pedagógica y Tecnológica de Colombia, Tunja (Colombia); Parra Vargas, C.A.; Barón-González, A.J. [Grupo Física de Materiales, Escuela de Física, Universidad Pedagógica y Tecnológica de Colombia, Tunja (Colombia); Sarmiento Santos, A. [Grupo Superficies Electroquímica y Corrosión, Escuela de Física, Universidad Pedagógica y Tecnológica de Colombia, Tunja (Colombia); Frontera, C. [Institut de Ciència de Materials de Barcelona, CSIC, Campus Universitari de Bellaterra, E-08193, Bellaterra, Barcelona (Spain)

    2016-08-15

    Neutron powder diffraction experiments and magnetic measurements in polycrystalline CaMn{sub 1−x}Mo{sub x}O{sub 3} (x = 0.08, 0.10, 0.12) point towards a possible charge and orbital order in this system. The analysis of structural and magnetic data show that the samples present structural phase transformation from Pnma to P2{sub 1}/m space group and the system has a C-type antiferromagnetic configuration at low temperature. A detailed analysis of the bond distances signals a small Jahn-Teller distortion of only one (x = 0.08) or of the two Mn ions (x = 0.10, 0.12). We identify the partially occupied e{sub g} orbitals and this explains the C-type magnetic structure. - Highlights: • CaMn{sub 1−x}Mo{sub x}O{sub 3} (x = 0.08, 0.10, 0.12) is investigated by neutron powder diffraction. • Analysis of individual Mn-O distances demonstrates the apparition of orbital order. • By symmetry analysis, we find that the low temperature magnetic structure is C-type. • Magnetic interactions foreseen by the orbital order explain the magnetic structure.

  9. M = Mo, W; X = S, Se, Te) heterostructures

    KAUST Repository

    Zhang, Qingyun

    2018-04-16

    Using first-principles calculations, we investigate the electronic properties of the two-dimensional GaX/MX2 (M = Mo, W; X = S, Se, Te) heterostructures. Orbital hybridization between GaX and MX2 is found to result in Rashba splitting at the valence-band edge around the Γ point, which grows for increasing strength of the spin-orbit coupling in the p orbitals of the chalcogenide atoms. The location of the valence-band maximum in the Brillouin zone can be tuned by strain and application of an out-of-plane electric field. The coexistence of Rashba splitting (in-plane spin direction) and band splitting at the K and K′ valleys (out-of-plane spin direction) makes GaX/MX2 heterostructures interesting for spintronics and valleytronics. They are promising candidates for two-dimensional spin-field-effect transistors and spin-valley Hall effect devices. Our findings shed light on the spin-valley coupling in van der Waals heterostructures.

  10. Chemical reactions during sintering of Fe-Cr-Mn-Si-Ni-Mo-C-steels with special reference to processing in semi-closed containers

    Directory of Open Access Journals (Sweden)

    Cias A.

    2015-01-01

    Full Text Available Sintering of Cr, Mn and Si bearing steels has recently attracted both experimental and theoretical attention and processing in semiclosed containers has been reproposed. This paper brings together relevant thermodynamic data and considers the kinetics of some relevant chemical reactions. These involve iron and carbon, water vapour, carbon monoxide and dioxide, hydrogen and nitrogen of the sintering atmospheres and the alloying elements Cr, Mn, Mo and Si. The paper concludes by presenting mechanical properties data for three steels sintered in local microatmosphere with nitrogen, hydrogen, nitrogen-5% hydrogen and air as the furnace gas.

  11. ¿Cómo estás atención? Cuáles son y cómo se evalúan las redes neuronales de la atención

    Directory of Open Access Journals (Sweden)

    Fernando Gabriel Luna

    2016-01-01

    Full Text Available Nuestro sistema cognitivo cuenta con redes neuronales que desarrollan diferentes funciones atencionales para afrontar la complejidad estimular del medio ambiente y adaptar nuestro comportamiento a la naturaleza y exigencia de múltiples situaciones. Las redes de la atención conforman un sistema de estructuras cerebrales específicas conectadas y sincronizadas entre sí que nos permiten orientarnos, alertarnos ante algunas señales, sostener nuestra atención, y seleccionar y controlar ciertos estímulos. A continuación se describe la estructura de estas redes, cómo operan en diversas situaciones, y cómo es posible obtener una medida confiable del rendimiento de cada una de las funciones atencionales.

  12. The fundamental absorption edge in MnIn{sub 2}Se{sub 4} layer semi-magnetic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Rincón, C., E-mail: crincon@ula.ve [Centro de Estudios de Semiconductores, Departamento de Física, Facultad de Ciencias, Universidad de Los Andes, Mérida (Venezuela, Bolivarian Republic of); Torrres, T.E. [Laboratorio de Magnetismo, Departamento de Física, Facultad de Ciencias, Universidad de Los Andes, Mérida (Venezuela, Bolivarian Republic of); Instituto de Nanociencia de Aragón, Laboratorio de Microscopías Avanzadas, Universidad de Zaragoza 50009, Zaragoza (Spain); Departamento de Física de la Materia Condensada, Facultad de Ciencias, Universidad de Zaragoza 50009, Zaragoza, Spain. (Spain); Sagredo, V. [Laboratorio de Magnetismo, Departamento de Física, Facultad de Ciencias, Universidad de Los Andes, Mérida (Venezuela, Bolivarian Republic of); Jiménez-Sandoval, Sergio J.; Mares-Jacinto, E. [CINVESTAV Querétaro, Libramiento Norponiente N° 2000, Frac. Real de Juriquilla, Querétaro, Qro. 76230 (Mexico)

    2015-11-15

    From the study of the optical absorption coefficient and photoluminescence spectra of the layer semi-magnetic semiconductor MnIn{sub 2}Se{sub 4} the nature of its fundamental absorption edge is established. It is found that the lowest-energy-gap of this compound is allowed-indirect between parabolic bands that vary from about 1.55–1.43 eV in the temperature range from 10 K to room temperature. In addition, two allowed direct band-to-band transitions beginning at 1.72 and 1.85 eV at 295 K, and at 1.82 and 1.96 eV at 10 K which are related to optical absorption processes between the uppermost Γ{sub 4}(z) and the middle Γ{sub 5}(x) valence bands and the conduction band respectively, are observed in the high energy range. It is also found that the crystal field splitting parameter (Δ{sub cf}) of MnIn{sub 2}Se{sub 4} is of about 0.15 eV nearly independent of the temperature. At energies around 2.2 eV a photoluminescence band related to internal transitions between d-excited levels of Mn{sup +2} ion to its {sup 6}A{sub 1} ground state is also observed in spectra.

  13. A fractographic study of cracks produced by thermal shocks in 20MnMoNi55 and comparable weld material in water environment

    International Nuclear Information System (INIS)

    Toerroenen, K.; Rintamaa, R.; Kemppainen, M.

    1983-04-01

    This report gives the results of a fractographic study of cracks produced by thermal shocks in 20MnMoNi55 and comparable weld material in water environment. The basic crack growth mechanism is shown to be by mechanical fatigue, but after some crack growth indications of environmentally assisted cyclic crack growth is seen. (author)

  14. Role of Mn2+ concentration in the linear and nonlinear optical properties of Ni1-xMnxSe nanoparticles

    Science.gov (United States)

    Anugop, B.; Prasanth, S.; Rithesh Raj, D.; Vineeshkumar, T. V.; Pranitha, S.; Mahadevan Pillai, V. P.; Sudarsanakumar, C.

    2016-12-01

    Ni1-xMnxSe nanoparticles (x = 0.1, 0.3, 0.5, 0.7, 0.9) were successfully synthesized by chemical co-precipitation method and their structural and optical properties were studied using X-ray diffraction, transmission electron microscopy, UV-Visible absorption and photo luminescence spectroscopy. XRD pattern reveals the hexagonal structure of the particles and the peak positions were shifted to higher 2θ values with increase in Mn2+ concentration. The average particle size determined from XRD varies from 6 to 11 nm. The UV-Visible absorption spectrum shows absorption edge around the blue region and is red-shifted with increasing Mn2+ concentration consequently the optical bandgap energy is decreasing. The PL emission spectrum shows a broad emission around 380 nm, and the intensity of the emission decreases with increase in Mn2+ concentration. The nonlinear optical properties of the samples were analysed using Z-scan technique and the samples show optical limiting behaviour and the 2 PA coefficient increases with increasing Mn2+ concentration. Overall, manganese concentration influences the linear and nonlinear optical properties of Ni1-xMnxSe nanoparticles.

  15. Transistor properties of exfoliated single crystals of 2 H -Mo (Se1-xT ex ) 2(0 ≤x ≤1 )

    Science.gov (United States)

    Uesugi, Eri; Miao, Xiao; Ota, Hiromi; Goto, Hidenori; Kubozono, Yoshihiro

    2017-06-01

    Field-effect transistors (FETs) were fabricated using exfoliated single crystals of Mo (Se1-xT ex) 2 with an x range of 0 to 1, and the transistor properties fully investigated at 295 K in four-terminal measurement mode. The chemical composition and crystal structure of exfoliated single crystals were identified by energy-dispersive x-ray spectroscopy (EDX), single-crystal x-ray diffraction, and Raman scattering, suggesting the 2 H - structure in all Mo (Se1-xT ex) 2 . The lattice constants of a and c increase monotonically with increasing x , indicating the substitution of Se by Te. When x 0.4 . In contrast, the polarity of a thick single-crystal Mo (Se1-xT ex) 2 FET did not change despite an increase in x . The change of polarity in a thin single-crystal FET was well explained by the variation of electronic structure. The absence of such change in the thick single-crystal FET can be reasonably interpreted based on the large bulk conduction due to naturally accumulated electrons. The μ value in the thin single-crystal FET showed a parabolic variation, with a minimum μ at around x =0.4 , which probably originates from the disorder of the single crystal caused by the partial replacement of Se by Te, i.e., a disorder that may be due to ionic size difference of Se and Te.

  16. Quality of Metal Deposited Flux Cored Wire With the System Fe-C-Si-Mn-Cr-Mo-Ni-V-Co

    Science.gov (United States)

    Gusev, Aleksander I.; Kozyrev, Nikolay A.; Osetkovskiy, Ivan V.; Kryukov, Roman E.; Kozyreva, Olga A.

    2017-10-01

    Studied the effect of the introduction of vanadium and cobalt into the charge powder fused wire system Fe-C-Si-Mn-Cr-Ni-Mo-V, used in cladding assemblies and equipment parts and mechanisms operating under abrasive and abrasive shock loads. the cored wires samples were manufactured in the laboratory conditions and using appropriate powder materials and as a carbonfluoride contained material were used the dust from gas purification of aluminum production, with the following components composition, %: Al2O3 = 21-46.23; F = 18-27; Na2O = 8-15; K2O = 0.4-6; CaO = 0.7-2.3; Si2O = 0.5-2.48; Fe2O3 = 2.1-3.27; C = 12.5-30.2; MnO = 0.07-0.9; MgO = 0.06-0.9; S = 0.09-0.19; P = 0.1-0.18. Surfacing was produced on the St3 metal plates in 6 layers under the AN-26C flux by welding truck ASAW-1250. Cutting and preparation of samples for research had been implemented. The chemical composition and the hydrogen content of the weld metal were determined by modern methods. The hardness and abrasion rate of weld metal had been measured. Conducted metallographic studies of weld metal: estimated microstructure, grain size, contamination of oxide non-metallic inclusions. Metallographic studies showed that the microstructure of the surfaced layer by cored wire system Fe-C-Si-Mn-Cr-Mo-Ni-V-Co is uniform, thin dendrite branches are observed. The microstructure consists of martensite, which is formed inside the borders of the former austenite grain retained austenite present in small amounts in the form of separate islands, and thin layers of δ-ferrite, which is located on the borders of the former austenite grains. Carried out an assessment the effect of the chemical composition of the deposited metal on the hardness and wear and hydrogen content. In consequence of multivariate correlation analysis, it was determined dependence to the hardness of the deposited layer and the wear resistance of the mass fraction of the elements included in the flux-cored wires of the system Fe-C-Si-Mn-Cr-Mo

  17. Lattice parameter values and phase transitions for the Cu{sub 2}Cd{sub 1-z}Mn{sub z}SnSe{sub 4} and Cu{sub 2}Cd{sub 1-z}Fe{sub z}SnSe{sub 4} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, E. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela, Bolivarian Republic of); Quintero, M., E-mail: mquinter@ula.v [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela, Bolivarian Republic of); Morocoima, M.; Quintero, E.; Grima, P.; Tovar, R.; Bocaranda, P. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela, Bolivarian Republic of); Delgado, G.E.; Contreras, J.E. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela, Bolivarian Republic of); Mora, A.E.; Briceno, J.M.; Avila Godoy, R.; Fernandez, J.L. [Laboratorio de Analisis Quimico y Estructural de Materiales, Departamento de Fisica, Universidad de Los Andes, Merida 5101 (Venezuela, Bolivarian Republic of); Henao, J.A.; Macias, M.A. [Grupo de Investigacion en Quimica Estructural (GIQUE), Facultad de Ciencias, Escuela de Quimica, Universidad Industrial de Santander, Apartado aereo 678, Bucaramanga (Colombia)

    2009-11-03

    X-ray powder diffraction measurements and differential thermal analysis (DTA) were made on polycrystalline samples of the Cu{sub 2}Cd{sub 1-z}Mn{sub z}SnSe{sub 4} and Cu{sub 2}Cd{sub 1-z}Fe{sub z}SnSe{sub 4} alloy systems. The diffraction patterns were used to show the equilibrium conditions and to derive lattice parameter values. For Cu{sub 2}Cd{sub 0.8}Fe{sub 0.2}SnSe{sub 4} as well as for Cu{sub 2}Cd{sub 0.2}Fe{sub 0.8}SnSe{sub 4} the crystal structures were refined using the Rietveld method. It was found that the internal distortion parameter sigma decreases as Cd is replaced by either Mn and/or Fe. For the Cu{sub 2}Cd{sub 1-z}Mn{sub z}SnSe{sub 4} and Cu{sub 2}Cd{sub 1-z}Fe{sub z}SnSe{sub 4} alloy systems, only two single solid phase fields, the tetragonal stannite alpha(I4-bar2m) and the wurtz-stannite delta (Pmn2{sub 1}) structures were found to occur in the diagram. In addition to the tetragonal stannite alpha phase extra X-ray diffraction lines due to MnSe and/or FeSe{sub 2} were observed for as grown samples in the range 0.7 < z < 1.0. However, it was found that the amount of the extra phase decreased for the compressed samples.

  18. Cryogenic deformation microstructures of 32Mn-7Cr-1Mo-0.3N austenitic steels

    International Nuclear Information System (INIS)

    Fu Ruidong; Qiu Liang; Wang Tiansheng; Wang Cunyu; Zheng Yangzeng

    2005-01-01

    The cryogenic deformation microstructures of impact and tensile specimens of 32Mn-7Cr-1Mo-0.3N austenitic steel were investigated using light microscopy and transmission electron microscopy. The results show that the deformation microstructures of the impact specimens are mainly composed of stacking faults, network dislocation, slip bands, and a few mechanical twins and ε-martensite. These microstructures cross with each other in a crystal angle. The deformation microstructures of the tensile specimens consist only of massive slip bands, in which a few mechanical twins and ε-martenite are located. Because of the larger plastic deformation the slip band traces become bent. All the deformation microstructures are formed on the {111} planes and along the orientation

  19. The Effects of Post-Sintering Treatments on Microstructure and Mechanical Properties of Mn-Mo Steel

    Science.gov (United States)

    Fiał, Ch.

    2017-12-01

    The effect of heat treatment on density, hardness, microstructure and tensile properties of Fe-0.85Mo-1.3Mn-0.6C sintered steel were investigated. Pre-alloyed Astaloy 85Mo, ferromanganese and UF4 graphite powders were mixed for 60 minutes in a Turbula mixer and then pressed in single-action die at 660MPa to produce green compacts (according to PN EN ISO 2740).The compacts were sintered in a specially designed semi-closed container at 1120 or 1250°C for 60 minutes in N2. The chemical composition of the sintering atmosphere was modified by adding getter and/or activator into the container. Two different types of heat treatment in nitrogen were carried out: sinteraustempering at 525°C for 60 minutes; and sinterhardening with additional tempering at 200°C for 60 minutes. The slightly better combination of strength and plasticity of steel for both sintering temperatures were achieved after sinterhardening+tempering variant. Average values of 0.2% offset yield stress, ultimate tensile strength and elongation after sintering in 1250°C, were 415MPa, 700MPa, and 2.0%, respectively.

  20. Effect of O- and Mn-doping on superconductivity in FeTe{sub 0.5}Se{sub 0.5} superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Gohil S.; Haque, Zeba; Ganguli, Ashok K. [Department of Chemistry, Indian Institute of Technology, New Delhi (India); Neha, Prakriti; Patnaik, Satyabrata [School of Physical Science, Jawaharlal Nehru University, New Delhi (India); Gupta, Laxmi C. [Department of Chemistry, Indian Institute of Technology, New Delhi (India); Visiting project scientist at the:Solid State and Nanomaterials Research Laboratory, Department of Chemistry, IIT Delhi (India)

    2014-05-15

    The effect of oxygen substitution at the selenium site and manganese substitution at the iron site in FeTe{sub 0.5}Se{sub 0.5} superconductor was investigated. It was found that upon partial O substitution, T{sub c} marginally decreases as seen in both resistivity and magnetization experiments. T{sub c} decreases even by a small amount of oxygen concentration (as low as 1 %). This observation is in contrast against an earlier work on Fe(Te/Se) samples,1 wherein T{sub c} as well as superconducting volume fraction were reported to increase in the samples annealed in air. Mn-doping leads to a decrease in T{sub c} in FeTe{sub 0.5}Se{sub 0.5}, which one would expect considering pair-breaking due to Mn{sup 2+}-ions. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Local Conduction in Mo xW1- xSe2: The Role of Stacking Faults, Defects, and Alloying.

    Science.gov (United States)

    Bampoulis, Pantelis; Sotthewes, Kai; Siekman, Martin H; Zandvliet, Harold J W

    2018-04-18

    Here, we report on the surface conductivity of WSe 2 and Mo x W 1- x Se 2 (0 ≤ x ≤ 1) crystals investigated with conductive atomic force microscopy. We found that stacking faults, defects, and chemical heterogeneities form distinct two-dimensional and one-dimensional conduction paths on the transition metal dichalcogenide surface. In the case of WSe 2 , in addition to step edges, we find a significant amount of stacking faults (formed during the cleaving process) that strongly influence the surface conductivity. These regions are attributed to the alternation of the 2H and 3R polytypism. The stacking faults form regular 2D patterns by alternation of the underlying stacking order, with a periodicity that varies significantly between different regions and samples. In the case of Mo x W 1- x Se 2 , its conductivity has a localized nature, which depends on the underlying chemical composition and the Mo/W ratio. Segregation to W-rich and Mo-rich regions during the growth process leads to nonuniform conduction paths on the surface of the alloy. We found a gradual change of the conductivity moving from one region to the other, reminiscent of lateral band bending. Our results demonstrate the use of C-AFM as a nanoscopic tool to probe the electrical properties of largely inhomogeneous samples and show the complicated nature of the surface conductivity of TMDC alloys.

  2. Comparative effect of Al, Se, and Mo toxicity on NO3(-) assimilation in sunflower (Helianthus annuus L.) plants.

    Science.gov (United States)

    Ruiz, Juan M; Rivero, Rosa M; Romero, Luis

    2007-04-01

    Here, we study the effect caused by three trace elements--Al, Se, and Mo--applied at the same concentration (100 microM) and in their oxyanionic forms--NaAl(OH)(4), Na(2)SeO(4), and Na(2)MoO(4)--on NO(3)(-) assimilation (NO(3)(-), nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), and glutamate synthase (GOGAT) activities, and concentrations of amino acids and proteins) in sunflower (Helianthus annuus L. var. Kasol) plants. The most harmful element for sunflower plants proved to be selenate, followed by aluminate. On the contrary, the application of molybdate had no negative effect on the growth of this plant, suggesting the possibility of using sunflower for the phytoremediation of this metal, mainly in agricultural zones used for grazing where the excess of this element can provoke problems of molybdenosis in ruminants (particularly in cattle). In addition, we found that the alteration of NO(3)(-) assimilation by SeO(4)(2-) and Al(OH)(4)(-) directly influences the growth and development of plants, foliar inhibition of NR activity by SeO(4)(2-) being more harmful than the decrease in foliar availability of NO(3)(-) provoked by Al(OH)(4)(-).

  3. Fracture behaviour of steel 20 MnMoNi 5 5 under stress wave loading

    International Nuclear Information System (INIS)

    Clos, R.; Schreppel, U.; Veit, P.; Zencker, U.; Specht, E.

    1994-01-01

    Crack initiation in fine grained 20 MnMoNi 5 5 steel has been investigated under stress wave loading conditions in the temperature range from -50 C to 20 C by a loading setup similar the ''Split Hopkinson Pressure Bar'' technique. For temperatures up to 20 C, fracture occurs by cleavage and K Id approaches and falls below the reference fracture toughness, while at room temperature stable crack growth occurs with a J i close to the static initiation value of the J-integral. The analysis of the crack tip configuration suggests that stable crack growth is the result of the following simultaneously induced stochastical processes: generation of constrained local microcracks, blunting of the individual crack tips and the deformation of material bridges at different regions along the crack tip front. (orig.)

  4. First attempts towards the early detection of fatigued substructures using cyclic-loaded 20 MnMoNi 5 5 steel

    International Nuclear Information System (INIS)

    Dobmann, G.; Seibold, A.

    1992-01-01

    Materials subjected to cyclic loading undergo substructural changes which may affect service life. The low alloy, fine-grained structural steel 20 MnMoNi 5 5 is used to demonstrate how substructural changes detected using TEM techniques are a function of the number of cycles undergone. For a given cyclic loading the usage factor η=N/N f =0.5 can be derived. Initial investigations using nondestructive examination methods have indicated that substructural changes and magnetic variables can be correlated. (orig.)

  5. Detailed Visualization of Phase Evolution during Rapid Formation of Cu(InGa)Se2 Photovoltaic Absorber from Mo/CuGa/In/Se Precursors.

    Science.gov (United States)

    Koo, Jaseok; Kim, Sammi; Cheon, Taehoon; Kim, Soo-Hyun; Kim, Woo Kyoung

    2018-03-02

    Amongst several processes which have been developed for the production of reliable chalcopyrite Cu(InGa)Se 2 photovoltaic absorbers, the 2-step metallization-selenization process is widely accepted as being suitable for industrial-scale application. Here we visualize the detailed thermal behavior and reaction pathways of constituent elements during commercially attractive rapid thermal processing of glass/Mo/CuGa/In/Se precursors on the basis of the results of systematic characterization of samples obtained from a series of quenching experiments with set-temperatures between 25 and 550 °C. It was confirmed that the Se layer crystallized and then melted between 250 and 350 °C, completely disappearing at 500 °C. The formation of CuInSe 2 and Cu(InGa)Se 2 was initiated at around 450 °C and 550 °C, respectively. It is suggested that pre-heat treatment to control crystallization of Se layer should be designed at 250-350 °C and Cu(InGa)Se 2 formation from CuGa/In/Se precursors can be completed within a timeframe of 6 min.

  6. Mn-substituted perovskites RECoxMn1-xO3: a comparison between magnetic properties of LaCoxMn1-xO3 and GdCoxMn1-xO3

    Directory of Open Access Journals (Sweden)

    Barahona, P.

    2008-08-01

    Full Text Available Cooperative phenomena constitute important mechanisms to explain the magnetic properties of the perovskite manganites REMnO3, in which the rare-earth and/or Mn is partially replaced by divalent elements. In this way, the manganese ion changes its valence state (Mn3+ Mn4+, triggering strong magnetic interactions. In this work we describe the case of GdCoxMn1-xO3 (0.0 ≤ x ≤ 1.0 for which the antiferromagnetic interaction between the Gd sublattice and the Mn/Co network leads to a reversal of the magnetic moment at low temperature. No inversion is observed for the LaCoxMn1-xO3 series, in which the ordering temperature may attain a maximum of 235 K for LaCo0.50Mn0.50O3, while it is only 120 K for similar Co/Mn ratio in the case of GdCo0.50Mn0.50O3. Magnetic properties are described in terms of two regimes: one, for x 3 manganite and another one, for x > 0.5, when Mn substitutes Co in the GdCoO3 cobaltite, while the magnetic interactions are maximized at x(Co = 0.50. This hypothesis is discussed in terms of the respective oxidation states of both manganese (Mn3+ / Mn4+ and cobalt (Co2+ / Co3+.El fenómeno cooperativo constituye un importante mecanismo para explicar las propiedades magnéticas de las perovskitas manganitas TRMnO3, en las que el catión de tierra rara, TR, y/o el catión Mn3+ son parcialmente reemplazados por cationes divalentes. Por esta vía el ión de manganeso cambia de estado de valencia (Mn3+ Mn4+, generando fuertes interacciones magnéticas. En el presente trabajo se describe el caso de las soluciones sólidas GdCoxMn1-xO3 (0.0 ≤ x ≤ 1.0 para las que la interacción antiferromagnética entre la subred del Gd3+ y la red Mn/Co lleva a una inversión del momento magnético a baja temperatura. No se ha observado inversión para la serie LaCoxMn1-xO3, en que la temperatura de orden puede alcanzar un máximo de 235K para LaCo0.50Mn0.50O3, mientras que en el caso de GdCo0.50Mn0.50O3, en que sí se observa inversión, la

  7. Empirical Testing of the CySeMoL Tool for Cyber Security Assessment – Case Study of Linux Server and MySQL

    OpenAIRE

    Rabbani, Talvia

    2016-01-01

    In this Master Thesis, several common applications used with MySQL and Linux server are modelled using the Enterprise Architecture Analysis Tool (EAAT) and the Cyber Security Modelling Language (CySeMoL), both developed by the Department of Industrial Information and Control System (ICS) at KTH. The objective of this study is to use the CySeMoL tool to evaluate the feasibility and correctness of the tool by simulating some particular type of attacks on a real life Linux server. A few common a...

  8. First-Principles Study on the Structural Stability and Segregation Behavior of γ-Fe/Cr2N Interface with Alloying Additives M (M = Mn, V, Ti, Mo, and Ni

    Directory of Open Access Journals (Sweden)

    Hui Huang

    2016-07-01

    Full Text Available This study investigated the structural stability and electrochemical properties of alloying additives M (M = Mn, V, Ti, Mo, or Ni at the γ-Fe(111/Cr2N(0001 interface by the first-principles method. Results indicated that V and Ti were easily segregated at the γ-Fe(111/Cr2N(0001 interface and enhanced interfacial adhesive strength. By contrast, Ni and Mo were difficult to segregate at the γ-Fe(111/Cr2N(0001 interface. Moreover, the results of the work function demonstrated that alloying additives Mn reduced local electrochemical corrosion behavior of the γ-Fe(111/Cr2N(0001 interface by cutting down Volta potential difference (VPD between clean γ-Fe(111 and Cr2N(0001, while alloying additives V, Ti, Mo, and Ni at the γ-Fe(111/Cr2N(0001 interface magnified VPD between clean γ-Fe(111 and Cr2N(0001, which were low-potential sites that usually serve as local attack initiation points.

  9. The causes of relaxation- and hot cracking in the heat-affected zone of 22 NiMoCr 37 and 20 MnMoNi 55

    International Nuclear Information System (INIS)

    Schellhammer, W.

    1977-01-01

    Non-destructive and metallographic investigations with a view to relaxation cracking and hot cracking were carried out in 53 component-specific welds with wall thicknesses of 40 to 360 mm and 21 experimental welds with wall thicknesses of 140 to 275 mm of high-temperature, fine-grained structural steel 22 NiMoCr 37 as well as in 27 component-specific welds of high-strength, fine-grained structural steel 20 MnMoNi 55. Non-destructive tests and conventional metallographic analyses by means of transverse structure micrography were unable to give a sufficiently accurate picture of the two types of cracks in the micro- and millimeter range, a 'volumetric' method was employed (tangential structure micrography with stepwise abrasion) which permitted semi-automatic and fast evaluation. The experimental results showed the selective influence of several elements and led to the development of a method to evaluate the cumulative effect of the chemical elements on relaxation cracking and hot cracking by addition of the selective influence. The method gives quantitative data on material optimisation with regard to the reduction of brittle and crack-prone states and confirms the findings of welding simulation tests. (orig./IHOE) 891 IHOE/orig.- 892 HIS [de

  10. Survey of trace elements (Al, As, Cd, Cr, Co, Hg, Mn, Ni, Pb, Se, and Si) in retail samples of flavoured and bottled waters.

    Science.gov (United States)

    Barroso, M F; Ramos, S; Oliva-Teles, M T; Delerue-Matos, C; Sales, M G F; Oliveira, M B P P

    2009-01-01

    Concentrations of eleven trace elements (Al, As, Cd, Cr, Co, Hg, Mn, Ni, Pb, Se, and Si) were measured in 39 (natural and flavoured) water samples. Determinations were performed using graphite furnace electrothermetry for almost all elements (Al, As, Cd, Cr, Co, Mn, Ni, Pb, and Si). For Se determination hydride generation was used, and cold vapour generation for Hg. These techniques were coupled to atomic absorption spectrophotometry. The trace element content of still or sparkling natural waters changed from brand to brand. Significant differences between natural still and natural sparkling waters (p element was compared with the presence of flavours, preservatives, acidifying agents, fruit juice and/or sweeteners, according to the labelled composition. It was shown that flavoured waters generally increase the trace element content. The addition of preservatives and acidifying regulators had a significant influence on Mn, Co, As and Si contents (p < 0.05). Fruit juice can also be correlated to the increase of Co and As. Sweeteners did not provide any significant difference in Mn, Co, Se and Si content.

  11. Lattice parameter values and phase transitions for the Cu{sub 2}Cd{sub 1-z}Mn {sub z}GeSe{sub 4} and Cu{sub 2}Cd{sub 1-z}Fe {sub z}GeSe{sub 4} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Quintero, E. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela); Tovar, R. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela); Quintero, M. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela)]. E-mail: mquinter@ula.ve; Delgado, G.E. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela); Morocoima, M. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela); Caldera, D. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela); Ruiz, J. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela); Mora, A.E. [Laboratorio de Analisis Quimico y Estructural de Materiales, Departamento de Fisica, Universidad de Los Andes, Merida 5101 (Venezuela); Briceno, M. [Laboratorio de Analisis Quimico y Estructural de Materiales, Departamento de Fisica, Universidad de Los Andes, Merida 5101 (Venezuela); Fernandez, J.L. [Laboratorio de Analisis Quimico y Estructural de Materiales, Departamento de Fisica, Universidad de Los Andes, Merida 5101 (Venezuela)

    2007-04-25

    X-ray powder diffraction measurements and differential thermal analysis (DTA) were made on polycrystalline samples of the Cu{sub 2}Cd{sub 1-z}Mn {sub z}GeSe{sub 4} and Cu{sub 2}Cd{sub 1-z}Fe {sub z}GeSe{sub 4} alloy systems. The diffraction patterns were used to show the equilibrium conditions and to derive lattice parameter values. The effect of the annealing temperature and cooling rate to room temperature are discussed. For the Cu{sub 2}Cd{sub 1-z}Fe {sub z}GeSe{sub 4} system, only two single solid phase fields, the tetragonal stannite {alpha} and the wurtz-stannite {delta} structures were found to occur in the diagram. For the Cu{sub 2}Cd{sub 1-z}Mn {sub z}GeSe{sub 4} system, in addition to the tetragonal stannite {alpha} and the wurtz-stannite {delta} phases, MnSe was found to exist in the diagram. The DTA experiments showed that the cooling curves for both systems exhibited effects of undercooling.

  12. Synthesis and characterization of RUM catalysts (M=SE,MO,W,SN) applied in ORR for a PEMFC fuel battery; Sintesis y caracterizacion de catalizadores RUM (M=SE,MO,W,SN) aplicados en la RRO para una pila de combustible PEMFC

    Energy Technology Data Exchange (ETDEWEB)

    Ezeta-Mejia, A.; Arce Estrada, E.M. [Instituto Politecnico Nacional, Mexico, D.F. (Mexico)]. E-mail: araceli-ezeta@hotmail.com; earce@ipn.mx

    2009-09-15

    Proton exchange membrane fuel cells (PEMFC) have received a great deal of interest recently because of a variety of factors, such as low weight and volume, operating at low temperatures and offering a high combination of power density and high efficiency in the conversion of energy, making them adequate for portable applications. Nevertheless, oxygen reduction reaction (ORR) occurring in the cathode of the battery plays a determinant role as the limiting reaction. Therefore, more efficient electrocatalysts need to be used. The optimal electrocatalyst for this reaction is Pt, but because of its high cost, alternative low-cost electrocatalysts with high activity and stability have been sought. Many investigations have shown that the Pt-based binary catalysts, such as Pt-M (M= Co, Fe, etc.) present good electrocatalytic activity for ORR; other studies show that Ru-based catalysts (RuSe, RuSe,Mo, RuSeRh ) also have adequate activity for this reaction. This study reports on synthesis by mechanical alloying of RuPt{sub x}M (x=0, 0.6% and M=Se,Mo,W,Sn) electrocatalyst nanoparticles at different grinding durations (0, 20 and 40 h). The materials synthesized by mechanical alloying were characterized using sweep electron microscopy and x-ray diffraction, obtaining agglomerated and dispersed particles between 1 and 30 {mu}m. The electrocatalytic characterization was conducted using VC and EDR techniques in H{sub 2}SO{sub 4} 0.5 M solution at ambient temperatures. The systems present a reaction order of 1 with respect to ORR and an overall multi-electron transfer of 4e{sup -} for the formation of water. A comparison was made between the electrocatalytic activity in the presence and absence of Pt, showing that Pt increases the catalytic activity of the materials by at least 1 order of magnitude. [Spanish] Las pilas de combustible de Membrana de Intercambio Protonico (PEMFC) han recibido gran interes recientemente por diversos factores tales como su bajo peso y volumen, operan a

  13. Magnetic properties of the semimagnetic semiconductor Zn0.15Mn0.85Ga2Se4

    International Nuclear Information System (INIS)

    Cadenas, Ruben; Perez, Flor V.; Quintero, Miguel; Quintero, Eugenio; Tovar, Rafael; Morocoima, Manuel; Gonzalez, Jesus; Bocaranda, P.; Ruiz, J.; Broto, J.M.; Rakoto, H.

    2007-01-01

    We report on the magnetic measurements of the semimagnetic semiconductor Zn 0.15 Mn 0.85 Ga 2 Se 4 (ZMGSe). The DC susceptibility and high magnetic field indicate that the ZMGSe orders antiferromagnetically at T∼6 K and undergoes into a spin-flop phase below this temperature. Arrott plots and magnetic entropy changes were used to characterize the order of the transitions

  14. Dehydrogenation of propane in the presence of CO{sub 2} over polyacid chromium oxide catalysts modified by Mo, W and Mn

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.L.; Agafonov, Yu.A.; Gaidai, N.A.; Nekrasov, N.V.; Davydov, P.E. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Institute of Organic Chemistry

    2013-11-01

    Effective chromium oxide catalysts without additions and with addition of Mo, W and Mn were prepared and tested in long-duration experiments for propane dehydrogenation in the presence of CO{sub 2}. The optimal concentrations of metals were found. It was shown that the best combination of acid-base and redox properties necessary for a decrease of aggregation of chromium-oxide particles was observed over the following catalyst: (3.0 wt.%Cr-1.5 wt.% Mn)/SiO{sub 2}. This catalyst worked stably in durable tests (500 h). Mechanism of propane oxidative dehydrogenation was studied using unstationary response method. It was shown that the process mechanism was similar over all studied catalysts but the catalysts were differed by the adsorption capacity of the reaction components: CO{sub 2} was tied more firmly than C{sub 3}H{sub 6} over Cr and Cr-Mn, C{sub 3}H{sub 6} was tied more strongly than CO{sub 2} over Cr-W. The reverse water-gas shift reaction proceeded in more extent over chromium-oxide catalysts without additions. (orig.)

  15. Lattice parameters values and phase diagram for the Cu{sub 2}Zn{sub 1−z}Mn{sub z}GeSe{sub 4} alloy system

    Energy Technology Data Exchange (ETDEWEB)

    Caldera, D. [Centro de Estudios de Semiconductores, Departamento de Física, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101 (Venezuela, Bolivarian Republic of); Quintero, M., E-mail: mquinter@ula.ve [Centro de Estudios de Semiconductores, Departamento de Física, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101 (Venezuela, Bolivarian Republic of); Morocoima, M.; Moreno, E.; Quintero, E.; Grima-Gallardo, P.; Bocaranda, P. [Centro de Estudios de Semiconductores, Departamento de Física, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101 (Venezuela, Bolivarian Republic of); Henao, J.A.; Macías, M.A. [Grupo de Investigación en Química Estructural (GIQUE), Facultad de Ciencias, Escuela de Química, Universidad Industrial de Santander, Apartado aéreo 678, Bucaramanga (Colombia); Briceño, J.M.; Mora, A.E. [Laboratorio de Análisis Químico y Estructura de Materiales, Departamento de Física, Universidad de Los Andes, Mérida 5101 (Venezuela, Bolivarian Republic of)

    2014-11-25

    Highlights: • The samples were annealed at 500 °C for 1 month. • Samples in the ranges 0 < z < 0.375 had the tetragonal stannite α structure (I4{sup ¯}2m). • For 0.725 < z ⩽ 1 the wurtz–stannite δ structure (Pmn2{sub 1}). • Undercooling effects occur for samples in the range 0.725 < z < 0.925. - Abstract: The T(z) phase diagram of the Cu{sub 2}Zn{sub 1−z}Mn{sub z}GeSe{sub 4} alloy system is obtained from X-ray diffraction and differential thermal analysis DTA. At room temperature, the X-ray diffraction data showed that samples in the ranges 0 < z < 0.375 had the tetragonal stannite α structure (I4{sup ¯}2m), while for 0.725 < z ⩽ 1 the wurtz–stannite δ structure (Pmn2{sub 1}). The α and δ fields are separated by a relative wide three-phase field (α + δ + MnSe{sub 2}). The DTA thermograms were used to construct the phase diagram of the Cu{sub 2}Zn{sub 1−z}Mn{sub z}GeSe{sub 4} alloy system. It was confirmed that the Cu{sub 2}ZnGeSe{sub 4} and Cu{sub 2}MnGeSe{sub 4} compounds melt incongruently. It was observed that undercooling effects occur for samples in the range 0.725 < z < 0.925.

  16. Brain regional uptake of radioactive Sc, Mn, Zn, Se, Rb and Zr tracers into normal mice during aging

    International Nuclear Information System (INIS)

    Amano, R.; Enomoto, S.

    2001-01-01

    Radioactive multitracer technique was applied to study the brain regional uptake of trace elements by the normal mice during aging. The brain regional radioactivities of 46 Sc, 54 Mn, 65 Zn, 75 Se, 83 Rb and 88 Zr were measured 48 hours after intraperitoneal injection of a solution in normal mice aged 6 to 52 weeks to evaluate the brain regional (corpus striatum, cerebellum, cerebral cortex, hippocampus, and pons and medulla) uptakes. The radioactive distributions of 46 Sc, 54 Mn and 88 Zr tracers were variable and region-specific in the brain, while those of 65 Zn, 75 Se and 83 Rb tracers were comparable among all regions of interest. The brain regional uptakes of all tracers slightly increased with age from 10 to 28 weeks, and then remained constant during aging after 28 weeks. These uptake variations may be involved in the functional degenerative process of the blood-brain barrier during aging. (author)

  17. Li-adsorption on doped Mo2C monolayer: A novel electrode material for Li-ion batteries

    Science.gov (United States)

    Mehta, Veenu; Tankeshwar, K.; Saini, Hardev S.

    2018-04-01

    A first principle calculation has been used to study the electronic and magnetic properties of pristine and N/Mn-doped Mo2C with and without Li-adsorption. The pseudopotential method implemented in SIESTA code based on density functional theory with generalized gradient approximation (GGA) as exchange-correlation (XC) potential has been employed. Our calculated results revealed that the Li gets favorably adsorbed on the hexagonal centre in pristine Mo2C and at the top of C-atom in case of N/Mn-doped Mo2C. The doping of Mn and N atom increases the adsorption of Li in Mo2C monolayer which may results in enhancement of storage capacity in Li-ion batteries. The metallic nature of Li-adsorbed pristine and N/Mn-doped Mo2C monolayer implies a good electronic conduction which is crucial for anode materials for its applications in rechargeable batteries. Also, the open circuit voltage for single Li-adsorption in doped Mo2C monolayer comes in the range of 0.4-1.0 eV which is the optimal range for any material to be used as an anode material. Our result emphasized the enhanced performance of doped Mo2C as an anode material in Li-ion batteries.

  18. SeSaMoNet 2.0: Improving a Navigation System for Visually Impaired People

    Science.gov (United States)

    Ceipidor, Ugo Biader; Medaglia, Carlo Maria; Sciarretta, Eliseo

    The authors present the improvements obtained during the work done for the last installation of SeSaMoNet, a navigation system for blind people. First the mobility issues of visually impaired people are shown together with strategies to solve them. Then an overview of the system and of its main elements is given. Afterward, the reasons which brought to a re-design are explained and finally the main features of the last system revision for the application are presented and compared to the previous one.

  19. Measurement of target and double-spin asymmetries for the e<mo>→>p<mo>→eπ+(n)> reaction in the nucleon resonance region at low Q<mn>2mn>

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, X.; Adhikari, K. P.; Bosted, P.; Deur, A.; Drozdov, V.; El Fassi, L.; Kang, Hyekoo; Kovacs, K.; Kuhn, S.; Long, E.; Phillips, S. K.; Ripani, M.; Slifer, K.; Smith, L. C.; Adikaram, D.; Akbar, Z.; Amaryan, M. J.; Anefalos Pereira, S.; Asryan, G.; Avakian, H.; Badui, R. A.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A. S.; Briscoe, W. J.; Bültmann, S.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Chen, J. -P.; Chetry, T.; Choi, Seonho; Ciullo, G.; Clark, L.; Colaneri, L.; Cole, P. L.; Compton, N.; Contalbrigo, M.; Crede, V.; D' Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Djalali, C.; Dodge, G. E.; Dupre, R.; Egiyan, H.; El Alaoui, A.; Elouadrhiri, L.; Eugenio, P.; Fanchini, E.; Fedotov, G.; Fersch, R.; Filippi, A.; Fleming, J. A.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Gleason, C.; Golovach, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guler, N.; Guo, L.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hicks, K.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jenkins, D.; Jiang, H.; Jo, H. S.; Joosten, S.; Keller, D.; Khachatryan, G.; Khandaker, M.; Kim, A.; Kim, W.; Klein, F. J.; Kubarovsky, V.; Lanza, L.; Lenisa, P.; Livingston, K.; MacGregor, I. J. D.; Markov, N.; McKinnon, B.; Mirazita, M.; Mokeev, V.; Movsisyan, A.; Munevar, E.; Munoz Camacho, C.; Murdoch, G.; Nadel-Turonski, P.; Net, L. A.; Ni, A.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Paolone, M.; Paremuzyan, R.; Park, K.; Pasyuk, E.; Peng, P.; Pisano, S.; Pogorelko, O.; Price, J. W.; Puckett, A. J. R.; Raue, B. A.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schumacher, R. A.; Sharabian, Y. G.; Skorodumina, Iu.; Smith, G. D.; Sokhan, D.; Sparveris, N.; Stankovic, I.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Tian, Ye; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zhang, J.; Zonta, I.

    2016-10-01

    We report measurements of target- and double-spin asymmetries for the exclusive channel e<mo>→>p<mo>→eπ+(n)> in the nucleon resonance region at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). These asymmetries were extracted from data obtained using a longitudinally polarized NH3 target and a longitudinally polarized electron beam with energies 1.1, 1.3, 2.0, 2.3, and 3.0 GeV. The new results are consistent with previous CLAS publications but are extended to a low Q2 range from 0.0065 to 0.35 (GeV/c)2. The Q2 access was made possible by a custom-built Cherenkov detector that allowed the detection of electrons for scattering angles as low as 6 degrees. These results are compared with the unitary isobar models JANR and MAID, the partial-wave analysis prediction from SAID, and the dynamic model DMT. In many kinematic regions our results, in particular results on the target asymmetry, help to constrain the polarization-dependent components of these models.

  20. Submerged arc narrow gap welding of the steel DIN 20MnMoNi55

    International Nuclear Information System (INIS)

    Moraes, M.M.

    1987-01-01

    The methodology for submerged arc narrow gap welding for high thickness rolled steel DIN 20MnMoNi55 was developed, using din S3NiMo1 04 mm and 05 mm wires, and DIN 8B435 flux. For this purpose, submerged arc narrow gap welded joints with 50 mm and 120 mm thickness were made aiming the welding parameters optimization and the study of the influence of welding voltage, wire diameter and wire to groove face distance on the operational performance and on the welded joint quality, specially on the ISO-V impact toughness. These welded joints were checked by non-destructive mechanical and metallographic tests. Results were compared with those obtained by one 120 mm thickness submerged arc conventional gap welded joint, using the same base metal and consumables (05 mm wire). The analysis of the results shows that the increasing of the wire to groove face distance and the welding voltage increases the hardness and the ISO-V impact toughness of the weld metal. It shows that the reduction of the gap angle is the main cause for the obtained of a heat affected zone free from coarse grains, the reduction of the welding voltage, the increasing of the wire to groove face distance, and the grounding optimization also contribute for that. It was also concluded that the quality and the execution complexity level of a narrow gap welded joint are identical to a conventional gap welded joint. (author) [pt

  1. Micronutrients (B, Co, Cu, Fe, Mn, Mo, and Zn) content in made tea (Camellia sinensis L.) and tea infusion with health prospect: A critical review.

    Science.gov (United States)

    Karak, Tanmoy; Kutu, Funso Raphael; Nath, Jyoti Rani; Sonar, Indira; Paul, Ranjit Kumar; Boruah, Romesh Kumar; Sanyal, Sandip; Sabhapondit, Santanu; Dutta, Amrit Kumar

    2017-09-22

    Tea (Camellia sinensis L.) is a perennial acidophilic crop, and known to be a nonalcoholic stimulating beverage that is most widely consumed after water. The aim of this review paper is to provide a detailed documentation of selected micronutrient contents, viz. boron (B), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), and zinc (Zn) in made tea and tea infusion. Available data from the literature were used to calculate human health aspect associated with the consumption of tea infusion. A wide range of micronutrients reported in both made tea and tea infusion could be the major sources of micronutrients for human. The content of B, Co, Cu, Fe, Mn, Mo, and Zn in made tea are ranged from 3.04 to 58.44 μg g -1 , below detectable limit (BDL) to 122.4 μg g -1 , BDL to 602 μg g -1 , 0.275 to 13,040 μg g -1 , 0.004 to 15,866 μg g -1 , 0.04 to 570.80 μg g -1 and 0.01 to 1120 μg g -1 , respectively. Only 3.2 μg L -1 to 7.25 mg L -1 , 0.01 μg L -1 to 7 mg L -1 , 3.80 μg L -1 to 6.13 mg L -1 , 135.59 μg L -1 -11.05 mg L -1 , 0.05 μg L -1 to 1980.34 mg L -1 , 0.012 to 3.78 μg L -1 , and 1.12 μg L -1 to 2.32 μg L -1 of B, Co, Cu, Fe, Mn, Mo, and Zn, respectively, are found in tea infusion which are lower than the prescribed limit of micronutrients in drinking water by World Health Organization. Furthermore, micronutrient contents in tea infusion depend on infusion procedure as well as on the instrument used for analysis. The proportion of micronutrients found in different tea types are 1.0-88.9% for B, 10-60% for Co, 2.0-97.8% for Cu, 67.8-89.9% for Fe, 71.0-87.4% for Mn, 13.3-34% for Mo, and 34.9-83% for Zn. From the results, it can also be concluded that consumption of three cups of tea infusion per day does not have any adverse effect on human health with respect to the referred micronutrients rather got beneficial effects to human.

  2. Cinética e equilíbrio de adsorção dos oxiânions Cr (VI, Mo (VI e Se (VI pelo sal de amônio quaternário de quitosana Kinetics and equilibrium of adsorption of oxyanions Cr (VI, Mo (VI and Se (VI by quaternary ammonium chitosan salt

    Directory of Open Access Journals (Sweden)

    Viviane A. Spinelli

    2005-07-01

    Full Text Available O sal quaternário de quitosana foi sintetizado com cloreto de glicidil trimetil amônio. A modificação química foi caracterizada por espectrometria no IV, RMN de 13C e ¹H, e mmol/g de grupos quaternários presentes na matriz polimérica por condutimetria. A remoção de Cr (VI, Mo (VI e Se (VI, em meio aquoso, foi investigada em processo de batelada. A adsorção mostrou ser dependente do pH para o Cr (VI e Se (VI, com um pH ótimo de adsorção, entre 4,0 a 6,0. Para o Mo (VI a adsorção manteve-se quase constante no intervalo de pH entre 4,0 e 11,5. O modelo de isoterma de Langmuir descreveu melhor os dados de equilíbrio na faixa de concentração investigada. No presente estudo, um grama do sal quaternário de quitosana reticulado com glutaraldeído adsorveu 68,3 mg de Cr, 63,4 mg de Mo e 90,0 mg de Se. A velocidade de adsorção, no processo, segue a equação cinética de pseudo segunda-ordem, sendo que o equilíbrio para os três íons foi alcançado próximo aos 200 minutos. A análise dispersiva de raios-X para o Cr (VI mostrou que o principal mecanismo de adsorção é a troca iônica entre os íons Cl- da superfície do polímero pelos oxiânions. O trocador aniônico apresentou a seguinte ordem de seletividade: Cr (VI > Mo (VI > Se (VI.Quaternary chitosan salt was synthesized in the presence of glycidyl trimetyl ammonium chloride. The polymer was characterized by spectroscopic techniques: infrared, 13C and ¹H NMR, while the amount of quaternary ammonium groups was obtained by condutimetry. The removal of Cr (VI, Mo (VI and Se (VI from aqueous solutions was carried out in batch adsorption processes. The process seemed to be pH dependent for Cr (VI and Se (VI with an optimum pH ranging from 4.0 to 6.0; while for Mo (VI the adsorption remained almost constant within the range between 4.0 and 11.5. The Langmuir isotherm model provided the best fit of the equilibrium data over the whole concentration investigated. In the experiment

  3. Adsorption of As, B, Cr, Mo and Se from coal fly ash leachate by Fe3 modified bentonite clay

    CSIR Research Space (South Africa)

    Vhahangwele, M

    2015-01-01

    Full Text Available Fly ash contains the potentially toxic elements As, B, Cr, Mo and Se which upon contact with water may be leached to contaminate surface and subsurface water bodies. This study aims to evaluate the adsorption of these elements from coal fly ash...

  4. The effects of minor alloy modifications and heat treatment on the microstructure and creep rupture behavior of 2.25Cr-1Mo Steel

    International Nuclear Information System (INIS)

    Todd, J.A.; Chung, D.W.; Parker, E.R.

    1983-01-01

    The effects of alloy additions on the microstructure of simulated cooled and tempered 2.25Cr-1Mo steels have been studied using transmission electron microscopy. Carbide precipitation sequences have been identified in the modification 3Cr-1Mo-1Mn-1Ni and compared to those in 2.25Cr-1Mo steels modified with Mn and Ni and also with Ti, V and B. The influence of minor compositional changes on the creep rupture behavior of 2.25Cr-1Mo steel has been studied at 500 C, 560 C, and 600 C. The most significant effect of alloy modifications on creep properties resulted from additions of Mn and Cr. Preliminary studies show that 1% Mn and 0.5Mn + 1Ni + 0.75Cr additions significantly reduce creep strength at all three temperatures for tests up to 2000 hours duration. The 3Cr-1Mo-1Mn-1Ni steel showed improvements in rupture ductility at all temperatures when compared with the base 2.25Cr-1Mo steel and the manganese-nickel modifications. Plots of the Larson-Miller parameter for both these modifications lay within the scatter band for commercial 2.25Cr-1Mo steels

  5. Arsenic and Mn levels in Isaza (Gymnogobius isaza) during the mass mortality event in Lake Biwa, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, Sawako Horai; Hayase, Daisuke; Eguchi, Akifumi; Itai, Takaaki; Nomiyama, Kei; Isobe, Tomohiko; Agusa, Tetsuro [Center for Marine Environmental Studies (CMES), Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577 (Japan); Ishikawa, Toshiyuki [Department of Environmental Education, Faculty of Education, Shiga University, 2-5-1 Hiratsu, Otsu, Shiga 520-0862 (Japan); Kumagai, Michio [Lake Biwa Environmental Research Institute, 5-34 Yanagasaki, Otsu, Shiga 520-0022 (Japan); Tanabe, Shinsuke, E-mail: shinsuke@agr.ehime-u.ac.jp [Center for Marine Environmental Studies (CMES), Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577 (Japan)

    2011-10-15

    The present study measured the concentrations of 25 elements (Li, Mg, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, Hg, Tl, Pb and Bi) in the whole body of Isaza which is an endemic fish species to Lake Biwa, Japan, and compared the values in the specimens from the mass mortality Isaza (MMI) and normal fresh Isaza (NFI). The mean levels of Mn and total As (T-As) were relatively higher in MMI than in NFI. In the T-As, highly toxic inorganic As was detected in MMI. Moreover we found Mn and As concentrations in surface sediment were extremely high and temporally increased. From all these results, we could infer that the dissolution of Mn and As from surface sediment of Lake Biwa might have been one of the cause for the mass mortality of Isaza. - Highlights: > Mn and As levels were significantly higher in MMI than in NFI. > The number of chemical species of As detected from MMI was less than that from NFI. > Mn and As levels were highest in surface sediment, and sharply decreased with depth. > Mn and As levels in surface sediment temporally increased. - As and Mn levels in dead Isaza caused by mass mortality.

  6. Fabrication of a 3D Hierarchical Sandwich Co9 S8 /α-MnS@N-C@MoS2 Nanowire Architectures as Advanced Electrode Material for High Performance Hybrid Supercapacitors.

    Science.gov (United States)

    Kandula, Syam; Shrestha, Khem Raj; Kim, Nam Hoon; Lee, Joong Hee

    2018-05-10

    Supercapacitors suffer from lack of energy density and impulse the energy density limit, so a new class of hybrid electrode materials with promising architectures is strongly desirable. Here, the rational design of a 3D hierarchical sandwich Co 9 S 8 /α-MnS@N-C@MoS 2 nanowire architecture is achieved during the hydrothermal sulphurization reaction by the conversion of binary mesoporous metal oxide core to corresponding individual metal sulphides core along with the formation of outer metal sulphide shell at the same time. Benefiting from the 3D hierarchical sandwich architecture, Co 9 S 8 /α-MnS@N-C@MoS 2 electrode exhibits enhanced electrochemical performance with high specific capacity/capacitance of 306 mA h g -1 /1938 F g -1 at 1 A g -1 , and excellent cycling stability with a specific capacity retention of 86.9% after 10 000 cycles at 10 A g -1 . Moreover, the fabricated asymmetric supercapacitor device using Co 9 S 8 /α-MnS@N-C@MoS 2 as the positive electrode and nitrogen doped graphene as the negative electrode demonstrates high energy density of 64.2 Wh kg -1 at 729.2 W kg -1 , and a promising energy density of 23.5 Wh kg -1 is still attained at a high power density of 11 300 W kg -1 . The hybrid electrode with 3D hierarchical sandwich architecture promotes enhanced energy density with excellent cyclic stability for energy storage. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Theoretical investigation of electronic, magnetic and optical properties of ZnSe doped TM and co-doped with MnTM (TM: Fe, Cr, Co): AB-initio study

    Energy Technology Data Exchange (ETDEWEB)

    Behloul, M. [LMPHE (URAC 12), Departement of Physique, B.P. 1014, Faculty of Science, University Mohammed V, Rabat (Morocco); Salmani, E., E-mail: elmehdisalmani@gmail.com [LMPHE (URAC 12), Departement of Physique, B.P. 1014, Faculty of Science, University Mohammed V, Rabat (Morocco); Ez-Zahraouy, H. [LMPHE (URAC 12), Departement of Physique, B.P. 1014, Faculty of Science, University Mohammed V, Rabat (Morocco); Benyoussef, A. [LMPHE (URAC 12), Departement of Physique, B.P. 1014, Faculty of Science, University Mohammed V, Rabat (Morocco); The Institute for Nanomaterials and Nanotechnology, MAScIR (Moroccan Fondation for Advanced Science, Innovation and Research), Rabat (Morocco)

    2016-12-01

    Based upon the first principal spin density functional calculation, the electronic, magnetic and optical properties of ZnTMSe and ZnMnTMSe where TM=Fe, Cr, Co are studied using the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) method within the local density (LDA)and the self-interaction-corrected(SIC) approximation. The purpose of this study is to determine the effect of different type of dopant and concentration on ferromagnetic and half metallic behavior of ZnSe. Therefore the magnetic disorder local moment (DLM) and the ferromagnetic state are investigated for different concentrations of Mn, Fe, Cr and Co; also the advantages of co-doped ZnSe with TM elements, behavior at room temperature are discussed. The electronic structure and optical properties are studied employing the local density (LDA) and the self-interaction-corrected (SIC) approximation. Moreover, the X-ray spectra modeling are in good agreement with the electronic and magnetic properties results. - Highlights: • The magnetic properties of ZnSe codoped with MnY(Y: Fe, Cr, Co) has been investigated. • The half-metallic appears in ZnSe codoped with impurities at low concentration. • The advantages of codoped ZnSe with impurities at room temperature are discussed.

  8. Topological superconductor in quasi-one-dimensional Tl2 -xMo6Se6

    Science.gov (United States)

    Huang, Shin-Ming; Hsu, Chuang-Han; Xu, Su-Yang; Lee, Chi-Cheng; Shiau, Shiue-Yuan; Lin, Hsin; Bansil, Arun

    2018-01-01

    We propose that the quasi-one-dimensional molybdenum selenide compound Tl2 -xMo6Se6 is a time-reversal-invariant topological superconductor induced by intersublattice pairing, even in the absence of spin-orbit coupling (SOC). No noticeable change in superconductivity is observed in Tl-deficient (0 ≤x ≤0.1 ) compounds. At weak SOC, the superconductor prefers the triplet d vector lying perpendicular to the chain direction and two-dimensional E2 u symmetry, which is driven to a nematic order by spontaneous rotation symmetry breaking. The locking energy of the d vector is estimated to be weak and hence the proof of its direction would rely on tunneling or phase-sensitive measurements.

  9. Effects of air melting on Fe/0.3/3Cr/0.5Mo/2Mn and Fe/0.3C/3Cr/0.5Mo/2Ni structural alloy steels

    International Nuclear Information System (INIS)

    Steinberg, B.

    1979-06-01

    Changing production methods of a steel from vacuum melting to air melting can cause an increase in secondary particles, such as oxides and nitrides, which may have detrimental effects on the mechanical properties and microstructure of the alloy. In the present study a base alloy of Fe/0.3C/3Cr/0.5Mo with either 2Mn or 2Ni added was produced by air melting and its mechanical properties and microstructure were compared to an identical vacuum melted steel. Significant differences in mechanical behavior, morphology, and volume fraction of undissolved inclusions have been observed as a function of composition following air melting. For the alloy containing manganese, all properties remained very close to vacuum melted values but the 2Ni alloy displayed a marked loss in Charpy impact toughness and plane strain fracture toughness. This loss is attributed to an increase in volume fraction of secondary particles in the nickel alloy, as opposed to both the Mn alloy and vacuum melted alloys, as well as to substaintially increased incidence of linear coalescence of voids. Microstructural features are discussed

  10. Magnetic and structural properties of Mn-doped Bi.sub.2./sub.Se.sub.3./sub. topological insulators

    Czech Academy of Sciences Publication Activity Database

    Tarasenko, R.; Vališka, M.; Vondráček, Martin; Horáková, Kateřina; Tkáč, V.; Carva, K.; Baláž, P.; Holý, V.; Springholz, G.; Sechovský, V.; Honolka, Jan

    2016-01-01

    Roč. 481, Jan (2016), 262-267 ISSN 0378-4363 R&D Projects: GA ČR(CZ) GA14-30062S; GA MŠk LO1409; GA MŠk(CZ) LM2011029 Grant - others:AV ČR(CZ) Fellowship J. E. Purkyně Institutional support: RVO:68378271 Keywords : topological insulator * Mn-doped Bi 2 Se 3 * X-ray diffraction * X-ray photoemission * spectroscopy * ferromagnetism Subject RIV: BM - Solid Matter Physics ; Magnetism

  11. Effect of rapid thermal annealing on the Mo back contact properties for Cu_2ZnSnSe_4 solar cells

    International Nuclear Information System (INIS)

    Placidi, Marcel; Espindola-Rodriguez, Moises; Lopez-Marino, Simon; Sanchez, Yudania; Giraldo, Sergio; Acebo, Laura; Neuschitzer, Markus; Alcobé, Xavier; Pérez-Rodríguez, Alejandro; Saucedo, Edgardo

    2016-01-01

    The effect of a rapid thermal process (RTP) on the molybdenum (Mo) back contact for Cu_2ZnSnSe_4 (CZTSe) solar cells is here investigated. It is shown that the annealing of the Mo layer during 5 min at 550 °C, not only improves the crystalline quality of the back contact (avoiding the absorber decomposition at this region because Mo becomes more resistant to the selenization), but also helps achieving higher crystalline quality of the absorber with bigger grains, reducing the current leakage through the heterojunction. We demonstrate that this is related to the relaxation of the compressive stress of the CZTSe absorber, when synthesized on the RTP annealed substrates. CZTSe solar cells prepared on annealed Mo films exhibited higher short circuit current densities and higher open circuit voltages, resulting in 10% and 33% higher fill factors and efficiencies. - Highlights: • An RTP annealing applied for the first time on Mo for CZTSe solar cells. • Clear improvement of the efficiency from 5.7 to 7.6% with RTP treatment. • Discussion of this improvement with adequate material/device characterizations. • Stress-induced defects responsible of the electrical leakage are revealed.

  12. ¿Y eso cómo se come? La interculturalidad y las comidas familiares

    Directory of Open Access Journals (Sweden)

    Francisco Adame Gómez

    2015-10-01

    Full Text Available Las comidas familiares son un ritual común a muchas culturas pero único en cómo se parametriza en cada una de ellas. Cada una se rige por unas normas no explícitas que todos los comensales, al compartir la misma cultura, conocen. Sin embargo, cuando alguien de una cultura diferente participa en una comida de este tipo, pueden producirse malentendidos y choques culturales fruto del desconocimiento de esas normas. Estas situaciones incómodas pueden solucionarse trabajando la interculturalidad en el aula de E/LE. La actividad que proponemos parte de una reflexión sobre la cultura propia para compararla con la cultura meta, seguida de una divertida simulación en la que nuestros alumnos tendrán que ponerse en la piel de un español. Tiene una duración de unos 120 minutos y está pensada para el nivel B2, aunque es adaptable a cualquier otro nivel.

  13. Time-resolved photoluminescence study of CdSe/CdMnS/CdS core/multi-shell nanoplatelets

    International Nuclear Information System (INIS)

    Murphy, J. R.; Delikanli, S.; Demir, H. V.; Scrace, T.; Zhang, P.; Norden, T.; Petrou, A.; Thomay, T.; Cartwright, A. N.

    2016-01-01

    We used photoluminescence spectroscopy to resolve two emission features in CdSe/CdMnS/CdS and CdSe/CdS core/multi-shell nanoplatelet heterostructures. The photoluminescence from the magnetic sample has a positive circular polarization with a maximum centered at the position of the lower energy feature. The higher energy feature has a corresponding signature in the absorption spectrum; this is not the case for the low-energy feature. We have also studied the temporal evolution of these features using a pulsed-excitation/time-resolved photoluminescence technique to investigate their corresponding recombination channels. A model was used to analyze the temporal dynamics of the photoluminescence which yielded two distinct timescales associated with these recombination channels. The above results indicate that the low-energy feature is associated with recombination of electrons with holes localized at the core/shell interfaces; the high-energy feature, on the other hand, is excitonic in nature with the holes confined within the CdSe cores.

  14. Time-resolved photoluminescence study of CdSe/CdMnS/CdS core/multi-shell nanoplatelets

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, J. R. [Department of Electrical Engineering, State University of New York, University at Buffalo, Buffalo, New York 14260 (United States); Department of Physics, State University of New York, University at Buffalo, Buffalo, New York 14260 (United States); Delikanli, S.; Demir, H. V., E-mail: volkan@bilkent.edu.tr [LUMINOUS Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, Nanyang Technological University, Singapore 639798 (Singapore); Department of Electrical and Electronics Engineering, Department of Physics, UNAM−Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey); Scrace, T.; Zhang, P.; Norden, T.; Petrou, A., E-mail: petrou@buffalo.edu [Department of Physics, State University of New York, University at Buffalo, Buffalo, New York 14260 (United States); Thomay, T.; Cartwright, A. N. [Department of Electrical Engineering, State University of New York, University at Buffalo, Buffalo, New York 14260 (United States)

    2016-06-13

    We used photoluminescence spectroscopy to resolve two emission features in CdSe/CdMnS/CdS and CdSe/CdS core/multi-shell nanoplatelet heterostructures. The photoluminescence from the magnetic sample has a positive circular polarization with a maximum centered at the position of the lower energy feature. The higher energy feature has a corresponding signature in the absorption spectrum; this is not the case for the low-energy feature. We have also studied the temporal evolution of these features using a pulsed-excitation/time-resolved photoluminescence technique to investigate their corresponding recombination channels. A model was used to analyze the temporal dynamics of the photoluminescence which yielded two distinct timescales associated with these recombination channels. The above results indicate that the low-energy feature is associated with recombination of electrons with holes localized at the core/shell interfaces; the high-energy feature, on the other hand, is excitonic in nature with the holes confined within the CdSe cores.

  15. Neutron irradiation embrittlement of reactor pressure vessel steel 20 MnMoNi55 weld

    International Nuclear Information System (INIS)

    Ghoneim, M.M.

    1987-05-01

    The effect of neutron irradiation on the mechanical and fracture properties of an 'improved' 20 MnMoNi 55 Pressure Vessel Steel (PVS) weld was investigated. In addition to very low residual element content, especially Cu (0.035 wt.%), and relatively higher Ni content (0.9 wt.%), this steel has higher strength (30% more) than the steels used currently in nuclear reactor pressure vessels. The material was irradiated to 3.5x10 19 and 7x10 19 n/cm 2 (E > 1 Mev) at 290 0 C and 2.5x10 19 n/cm 2 (E > 1 MeV) at 160 0 C in FRJ-1 and FRJ-2 research reactors at KFA, Juelich, F.R.G. Test methods used in the evaluation included instrumented impact testing of standard and precracked Charpy specimens, tensile, and fracture toughness testing. Instrumented impact testing provided load and energy vs. time (deflection) data in addition to energy absorption data. The results indicated that the investigated high strength improved steel is more resistant to irradiation induced embrittlement than conventional PVSs. (orig./IHOE)

  16. The Synergy Effect of Ni-M (M = Mo, Fe, Co, Mn or Cr Bicomponent Catalysts on Partial Methanation Coupling with Water Gas Shift under Low H2/CO Conditions

    Directory of Open Access Journals (Sweden)

    Xinxin Dong

    2017-02-01

    Full Text Available Ni-M (M = Mo, Fe, Co, Mn or Cr bicomponent catalysts were prepared through the co-impregnation method for upgrading low H2/CO ratio biomass gas into urban gas through partial methanation coupling with water gas shift (WGS. The catalysts were characterized by N2 isothermal adsorption, X-ray diffraction (XRD, H2 temperature programmed reduction (H2-TPR, H2 temperature programmed desorption (H2-TPD, scanning electron microscopy (SEM and thermogravimetry (TG. The catalytic performances demonstrated that Mn and Cr were superior to the other three elements due to the increased fraction of reducible NiO particles, promoted dispersion of Ni nanoparticles and enhanced H2 chemisorption ability. The comparative study on Mn and Cr showed that Mn was more suitable due to its smaller carbon deposition rate and wider adaptability to various H2/CO and H2O/CO conditions, indicating its better synergy effect with Ni. A nearly 100 h, the lifetime test and start/stop cycle test further implied that 15Ni-3Mn was stable for industrial application.

  17. Analysis of whole human blood for Pb, Cd, Hg, Se, and Mn by ICP-DRC-MS for biomonitoring and acute exposures.

    Science.gov (United States)

    Jones, Deanna R; Jarrett, Jeffery M; Tevis, Denise S; Franklin, Melanie; Mullinix, Neva J; Wallon, Kristen L; Derrick Quarles, C; Caldwell, Kathleen L; Jones, Robert L

    2017-01-01

    We improved our inductively coupled plasma mass spectrometry (ICP-MS) whole blood method [1] for determination of lead (Pb), cadmium (Cd), and mercury (Hg) by including manganese (Mn) and selenium (Se), and expanding the calibration range of all analytes. The method is validated on a PerkinElmer (PE) ELAN® DRC II ICP-MS (ICP-DRC-MS) and uses the Dynamic Reaction Cell (DRC) technology to attenuate interfering background ion signals via ion-molecule reactions. Methane gas (CH 4 ) eliminates background signal from 40 Ar 2 + to permit determination of 80 Se + , and oxygen gas (O 2 ) eliminates several polyatomic interferences (e.g. 40 Ar 15 N + , 54 Fe 1 H + ) on 55 Mn + . Hg sensitivity in DRC mode is a factor of two higher than vented mode when measured under the same DRC conditions as Mn due to collisional focusing of the ion beam. To compensate for the expanded method's longer analysis time (due to DRC mode pause delays), we implemented an SC4-FAST autosampler (ESI Scientific, Omaha, NE), which vacuum loads the sample onto a loop, to keep the sample-to-sample measurement time to less than 5min, allowing for preparation and analysis of 60 samples in an 8-h work shift. The longer analysis time also resulted in faster breakdown of the hydrocarbon oil in the interface roughing pump. The replacement of the standard roughing pump with a pump using a fluorinated lubricant, Fomblin®, extended the time between pump maintenance. We optimized the diluent and rinse solution components to reduce carryover from high concentration samples and prevent the formation of precipitates. We performed a robust calculation to determine the following limits of detection (LOD) in whole blood: 0.07µgdL -1 for Pb, 0.10µgL -1 for Cd, 0.28μgL -1 for Hg, 0.99µgL -1 for Mn, and 24.5µgL -1 for Se. Published by Elsevier B.V.

  18. Fatigue damage evolution of cold-worked austenitic nickel-free high-nitrogen steel X13CrMnMoN18-14-3 (1.4452)

    Energy Technology Data Exchange (ETDEWEB)

    Tikhovskiy, I.; Weiss, S.; Fischer, A. [Univ. of Duisburg-Essen, Materials Science and Engineering II, Duisburg (Germany)

    2004-07-01

    Due to the fact that the risk of Ni-allergies becomes more and more important for modern therapies, the necessity of Ni-free implant materials becomes increasingly important. Beside Co- and Ti-base alloys Ni-free high-nitrogen steels may offer an attractive alternative. The present work presents the austenitic high-nitrogen and nickel-free steel X13CrMnMoN18-14-3, (Material No.: 1.4452) after 20% cold-working. In addition this material was deformed under axial cyclic total strain controlled fatigue tests at room temperature. The development of dislocation structure due to different loading amplitudes was compared to none cyclically deformed material. The good mechanical und fatigue properties of these austenitic high-nitrogen steels as well as the better tribological, chemical and biological properties compared to CrNiMo-steels qualify these steels as a promising alternative in medical applications. (orig.)

  19. Study on the absorption of Fe, Mn, Mo and Zn by two cultivars of pigeonpea (Cajanus cajan, Millsp) submitted to two doses of fertilizers using INAA

    International Nuclear Information System (INIS)

    Piasentin, R.M.; Armelin, M.J.A.; Saiki, M.

    2000-01-01

    Leaf samples of two varieties of Cajanus cajan Millsp were analysed by instrumental neutron activation analysis (INAA). The samples were taken from plants grown under two fertilizer dose conditions, making use of the following microminerals: Fe, Mn, Mo and Zn, which were applied individually to the soil. The samples were collected in two cutting times. We verify the variation in the absorption of each element, considering its availability in the soil. (author)

  20. Prediction of two-dimensional diluted magnetic semiconductors: Doped monolayer MoS2 systems

    KAUST Repository

    Cheng, Yingchun

    2013-03-05

    Using first-principles calculations, we propose a two-dimensional diluted magnetic semiconductor: monolayer MoS2 doped by transition metals. Doping of transition metal atoms from the IIIB to VIB groups results in nonmagnetic states, since the number of valence electrons is smaller or equal to that of Mo. Doping of atoms from the VIIB to IIB groups becomes energetically less and less favorable. Magnetism is observed for Mn, Fe, Co, Zn, Cd, and Hg doping, while for the other dopants from these groups it is suppressed by Jahn-Teller distortions. Analysis of the binding energies and magnetic properties indicates that (Mo,X)S2 (X=Mn, Fe, Co, and Zn) are promising systems to explore two-dimensional diluted magnetic semiconductors.

  1. Effect of rapid thermal annealing on the Mo back contact properties for Cu{sub 2}ZnSnSe{sub 4} solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Placidi, Marcel, E-mail: mplacidi@irec.cat [Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, pl.2, 08930 St Adrià del Besòs, Barcelona (Spain); Espindola-Rodriguez, Moises; Lopez-Marino, Simon; Sanchez, Yudania; Giraldo, Sergio; Acebo, Laura; Neuschitzer, Markus [Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, pl.2, 08930 St Adrià del Besòs, Barcelona (Spain); Alcobé, Xavier [Centres Científics i Tecnològics (CCiTUB), Lluis Solé i Sabarís 1, 08028 Barcelona (Spain); Pérez-Rodríguez, Alejandro [Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, pl.2, 08930 St Adrià del Besòs, Barcelona (Spain); IN2UB, Departament d’Electrònica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Saucedo, Edgardo [Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, pl.2, 08930 St Adrià del Besòs, Barcelona (Spain)

    2016-08-05

    The effect of a rapid thermal process (RTP) on the molybdenum (Mo) back contact for Cu{sub 2}ZnSnSe{sub 4} (CZTSe) solar cells is here investigated. It is shown that the annealing of the Mo layer during 5 min at 550 °C, not only improves the crystalline quality of the back contact (avoiding the absorber decomposition at this region because Mo becomes more resistant to the selenization), but also helps achieving higher crystalline quality of the absorber with bigger grains, reducing the current leakage through the heterojunction. We demonstrate that this is related to the relaxation of the compressive stress of the CZTSe absorber, when synthesized on the RTP annealed substrates. CZTSe solar cells prepared on annealed Mo films exhibited higher short circuit current densities and higher open circuit voltages, resulting in 10% and 33% higher fill factors and efficiencies. - Highlights: • An RTP annealing applied for the first time on Mo for CZTSe solar cells. • Clear improvement of the efficiency from 5.7 to 7.6% with RTP treatment. • Discussion of this improvement with adequate material/device characterizations. • Stress-induced defects responsible of the electrical leakage are revealed.

  2. Negative circular polarization emissions from WSe2/MoSe2 commensurate heterobilayers

    KAUST Repository

    Hsu, Wei-Ting; Lu, Li-Syuan; Wu, Po-Hsun; Lee, Ming-Hao; Chen, Peng-Jen; Wu, Pei-Ying; Chou, Yi-Chia; Jeng, Horng-Tay; Li, Lain-Jong; Chu, Ming-Wen; Chang, Wen-Hao

    2018-01-01

    Van der Waals heterobilayers of transition metal dichalcogenides with spin-valley coupling of carriers in different layers have emerged as a new platform for exploring spin/valleytronic applications. The interlayer coupling was predicted to exhibit subtle changes with the interlayer atomic registry. Manually stacked heterobilayers, however, are incommensurate with the inevitable interlayer twist and/or lattice mismatch, where the properties associated with atomic registry are difficult to access by optical means. Here, we unveil the distinct polarization properties of valley-specific interlayer excitons using epitaxially grown, commensurate WSe/MoSe heterobilayers with well-defined (AA and AB) atomic registry. We observe circularly polarized photoluminescence from interlayer excitons, but with a helicity opposite to the optical excitation. The negative circular polarization arises from the quantum interference imposed by interlayer atomic registry, giving rise to distinct polarization selection rules for interlayer excitons. Using selective excitation schemes, we demonstrate the optical addressability for interlayer excitons with different valley configurations and polarization helicities.

  3. Negative circular polarization emissions from WSe2/MoSe2 commensurate heterobilayers

    KAUST Repository

    Hsu, Wei-Ting

    2018-04-11

    Van der Waals heterobilayers of transition metal dichalcogenides with spin-valley coupling of carriers in different layers have emerged as a new platform for exploring spin/valleytronic applications. The interlayer coupling was predicted to exhibit subtle changes with the interlayer atomic registry. Manually stacked heterobilayers, however, are incommensurate with the inevitable interlayer twist and/or lattice mismatch, where the properties associated with atomic registry are difficult to access by optical means. Here, we unveil the distinct polarization properties of valley-specific interlayer excitons using epitaxially grown, commensurate WSe/MoSe heterobilayers with well-defined (AA and AB) atomic registry. We observe circularly polarized photoluminescence from interlayer excitons, but with a helicity opposite to the optical excitation. The negative circular polarization arises from the quantum interference imposed by interlayer atomic registry, giving rise to distinct polarization selection rules for interlayer excitons. Using selective excitation schemes, we demonstrate the optical addressability for interlayer excitons with different valley configurations and polarization helicities.

  4. ¿CÓMO SE HACE UN ANÁLISIS DEL ENTORNO ECONÓMICO EMPRESARIAL?

    Directory of Open Access Journals (Sweden)

    Carlos Parodi Trece

    2010-08-01

    Full Text Available La adecuada interpretación de la evolución de la economía constituye una herramienta útil para mejorarla toma de decisiones empresariales. El objetivo del artículo es explicar, con ejemplos aplicados a larealidad económica actual, cómo se hace un análisis del entorno económico y cómo este sirve para laplanificación estratégica empresarial. Para ello, previa explicación conceptual del marco general, sedefinen el producto interno bruto, la inflación y la brecha externa como indicadores de resultados, clavesen el «lenguaje» usado por los analistas. Son indicadores económicos, relacionados entre sí, que dependende la política económica interna y de choques exógenos, definidos estos últimos como eventos que estánfuera de las manos de los diseñadores de la política económica, pero que influyen en las tres variablesmencionadas, como, por ejemplo, la crisis financiera internacional. A continuación sigue la formalizaciónpor medio de las identidades macroeconómicas, para finalizar explicando «cómo va la economía» mediantelas mismas; así como, la relación entre el entorno económico interno con el externo. Acercar la economíaa la empresa debe ser una prioridad en un contexto cada vez más integrado, caracterizado por el hecho deque lo positivo y lo negativo de lo que ocurre en la economía mundial es transmitido, mediante diversoscanales, a las empresas ubicadas en distintos países. De ahí que las empresas deban ampliar su visión,pues el entorno económico no solo incluye lo que ocurre dentro del país, sino, cada vez con mayorrelevancia, el devenir de la economía mundial.

  5. Manganese-calcium intermixing facilitates heteroepitaxial growth at the <mn>10mn><mn>1mn>¯>4mn> calcite-water interface

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Man; Riechers, Shawn L.; Ilton, Eugene S.; Du, Yingge; Kovarik, Libor; Varga, Tamas; Arey, Bruce W.; Qafoku, Odeta; Kerisit, Sebastien

    2017-10-01

    In situ atomic force microscopy (AFM) measurements were performed to probe surface precipitates that formed on the (10-14) surface of calcite (CaCO3) single crystals following reaction with Mn2+-bearing aqueous solutions with a range of initial concentrations. Three-dimensional epitaxial islands were observed to precipitate and grow on the surfaces and in situ time-sequenced measurements demonstrated that their growth rates were commensurate with those obtained for epitaxial islands formed on calcite crystals reacted with Cd2+-bearing aqueous solutions of the same range in supersaturation with respect to the pure metal carbonate phase. This finding was unexpected as rhodochrosite (MnCO3) and calcite display a 10% lattice mismatch, based on the area of their (10-14) surface unit cells, whereas the lattice mismatch is only 4% for otavite (CdCO3) and calcite. Coatings of varying thicknesses were therefore synthesized by reacting calcite single crystals with calcite-equilibrated aqueous solutions with concentrations of up to 250 µM MnCl2 and analyzed to determine the composition of the surface precipitates. Ex situ X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray reflectivity (XRR), and AFM measurements of the reacted crystals demonstrated the formation of an epitaxial (Mn,Ca)CO3 solid solution with a spatially complex composition atop the calcite surface, whereby the first few nanometers were rich in Ca and the Mn content increased with distance from the original calcite surface, culminating in a topmost region of almost pure MnCO3 for the thickest coatings. These findings explain the measured growth rates (the effective lattice mismatch was much smaller than nominal mismatch) and highlight the strong influence played by the substrate on the composition of surface precipitates in aqueous conditions.

  6. Hydrophilic MoSe2 Nanosheets as Effective Photothermal Therapy Agents and Their Application in Smart Devices.

    Science.gov (United States)

    Lei, Zhouyue; Zhu, Wencheng; Xu, Shengjie; Ding, Jian; Wan, Jiaxun; Wu, Peiyi

    2016-08-17

    A facile poly(vinylpyrrolidone) (PVP)-assisted exfoliation method is utilized to simultaneously exfoliate and noncovalently modify MoSe2 nanosheets. The resultant hydrophilic nanosheets are shown to be promising candidates for biocompatible photothermal therapy (PTT) agents, and they could also be encapsulated into a hydrogel matrix for some intelligent devices. This work not only provides novel insights into exfoliation and modification of transition metal dichalcogenide (TMD) nanosheets but also might spark more research into engineering multifunctional TMD-related nanocomposites, which is in favor of further exploiting the attractive properties of these emerging layered two-dimensional (2D) nanomaterials.

  7. Ratiometric Phosphorescent Probe for Thallium in Serum, Water, and Soil Samples Based on Long-Lived, Spectrally Resolved, Mn-Doped ZnSe Quantum Dots and Carbon Dots.

    Science.gov (United States)

    Lu, Xiaomei; Zhang, Jinyi; Xie, Ya-Ni; Zhang, Xinfeng; Jiang, Xiaoming; Hou, Xiandeng; Wu, Peng

    2018-02-20

    Thallium (Tl) is an extremely toxic heavy metal and exists in very low concentrations in the environment, but its sensing is largely underexplored as compared to its neighboring elements in the periodic table (especially mercury and lead). In this work, we developed a ratiometric phosphorescent nanoprobe for thallium detection based on Mn-doped ZnSe quantum dots (QDs) and water-soluble carbon dots (C-dots). Upon excitation with 360 nm, Mn-doped ZnSe QDs and C-dots can emit long-lived and spectrally resolved phosphorescence at 580 and 440 nm, respectively. In the presence of thallium, the phosphorescence emission from Mn-doped ZnSe QDs could be selectively quenched, while that from C-dots retained unchanged. Therefore, a ratiometric phosphorescent probe was thus developed, which can eliminate the potential influence from both background fluorescence and other analyte-independent external environment factors. Several other heavy metal ions caused interferences to thallium detection but could be efficiently masked with EDTA. The proposed method offered a detection limit of 1 μg/L, which is among the most sensitive probes ever reported. Successful application of this method for thallium detection in biological serum as well as in environmental water and soil samples was demonstrated.

  8. Microchemistry of neutron irradiated 12%CrMoVNb martensitic steel

    International Nuclear Information System (INIS)

    Little, E.A.; Morgan, T.S.; Faulkner, R.G.

    1992-01-01

    Non-equilibrium solute segregation has been studied in a 12%CrMoVNb martensitic steel following fast reactor irradiation at 465 C and correlated with the development of M 6 X η-phase. Cr, Ni, Si, Mo, P and Mn are all shown to exhibit positive segregation to lath boundaries and are subsequently incorporated into M 6 X precipitates. The co-segregation of a combination of these elements which include P and Si, and possibly Cr or Mo, appears to promote M 6 X formation

  9. Determination of heavy metal deposition in the county of Obrenovac (Serbia using mosses as bioindicators, IV: Manganese (Mn, Molybdenum (Mo, and Nickel (Ni

    Directory of Open Access Journals (Sweden)

    Vukojević V.

    2009-01-01

    Full Text Available In this study, the deposition of three heavy metals (Mn, Mo, and Ni in the county of Obrenovac (Serbia in four moss taxa (Bryum argenteum, Bryum capillare, Brachythecium sp., and Hypnum cupressiforme is presented. The distribution of average heavy metal content in all mosses in the county of Obrenovac is presented on maps, while the long-term atmospheric deposition (in the mosses Bryum argenteum and B. capillare and short term atmospheric deposition (in the mosses Brachythecium sp. and Hypnum cupressiforme are discussed and given in tabular form. Areas of the highest contaminations are highlighted.

  10. Microstructural Characterization of Clad Interface in Welds of Ni-Cr-Mo High Strength Low Alloy Steel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong-Eun; Kim, Min-Chul; Lee, Ho-Jin; Kim, Keong-Ho [KAERI, Daejeon (Korea, Republic of); Lee, Ki-Hyoung [KAIST, Daejeon (Korea, Republic of); Lee, Chang-Hee [Hanyang Univ., Seoul (Korea, Republic of)

    2011-08-15

    SA508 Gr.4N Ni-Cr-Mo low alloy steel, in which Ni and Cr contents are higher than in commercial SA508 Gr.3 Mn-Mo-Ni low alloy steels, may be a candidate reactor pressure vessel (RPV) material with higher strength and toughness from its tempered martensitic microstructure. The inner surface of the RPV is weld-cladded with stainless steels to prevent corrosion. The goal of this study is to evaluate the microstructural properties of the clad interface between Ni-Cr-Mo low alloy steel and stainless weldment, and the effects of post weld heat treatment (PWHT) on the properties. The properties of the clad interface were compared with those of commercial Mn-Mo-Ni low alloy steel. Multi-layer welding of model alloys with ER308L and ER309L stainless steel by the SAW method was performed, and then PWHT was conducted at 610°C for 30 h. The microstructural changes of the clad interface were analyzed using OM, SEM and TEM, and micro-Vickers hardness tests were performed. Before PWHT, the heat affected zone (HAZ) showed higher hardness than base and weld metals due to formation of martensite after welding in both steels. In addition, the hardness of the HAZ in Ni-Cr-Mo low alloy steel was higher than that in Mn-Mo-Ni low alloy steel due to a comparatively high martensite fraction. The hardness of the HAZ decreased after PWHT in both steels, but the dark region was formed near the fusion line in which the hardness was locally high. In the case of Mn-Mo-Ni low alloy steel, formation of fine Cr-carbides in the weld region near the fusion line by diffusion of C from the base metal resulted in locally high hardness in the dark region. However, the precipitates of the region in the Ni-Cr-Mo low alloy steel were similar to that in the base metal, and the hardness in the region was not greatly different from that in the base metal.

  11. Microstructural Characterization of Clad Interface in Welds of Ni-Cr-Mo High Strength Low Alloy Steel

    International Nuclear Information System (INIS)

    Kim, Hong-Eun; Kim, Min-Chul; Lee, Ho-Jin; Kim, Keong-Ho; Lee, Ki-Hyoung; Lee, Chang-Hee

    2011-01-01

    SA508 Gr.4N Ni-Cr-Mo low alloy steel, in which Ni and Cr contents are higher than in commercial SA508 Gr.3 Mn-Mo-Ni low alloy steels, may be a candidate reactor pressure vessel (RPV) material with higher strength and toughness from its tempered martensitic microstructure. The inner surface of the RPV is weld-cladded with stainless steels to prevent corrosion. The goal of this study is to evaluate the microstructural properties of the clad interface between Ni-Cr-Mo low alloy steel and stainless weldment, and the effects of post weld heat treatment (PWHT) on the properties. The properties of the clad interface were compared with those of commercial Mn-Mo-Ni low alloy steel. Multi-layer welding of model alloys with ER308L and ER309L stainless steel by the SAW method was performed, and then PWHT was conducted at 610°C for 30 h. The microstructural changes of the clad interface were analyzed using OM, SEM and TEM, and micro-Vickers hardness tests were performed. Before PWHT, the heat affected zone (HAZ) showed higher hardness than base and weld metals due to formation of martensite after welding in both steels. In addition, the hardness of the HAZ in Ni-Cr-Mo low alloy steel was higher than that in Mn-Mo-Ni low alloy steel due to a comparatively high martensite fraction. The hardness of the HAZ decreased after PWHT in both steels, but the dark region was formed near the fusion line in which the hardness was locally high. In the case of Mn-Mo-Ni low alloy steel, formation of fine Cr-carbides in the weld region near the fusion line by diffusion of C from the base metal resulted in locally high hardness in the dark region. However, the precipitates of the region in the Ni-Cr-Mo low alloy steel were similar to that in the base metal, and the hardness in the region was not greatly different from that in the base metal.

  12. Se interlayer in CIGS absorption layer for solar cell devices

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung-Kyu; Sim, Jae-Kwan [Semiconductor Materials Process Laboratory, School of Advanced Materials Engineering, Research Center for Advanced Materials Development, Chonbuk National University, Deokjin-Dong 664-14, Jeonju 561-756 (Korea, Republic of); Kissinger, N.J. Suthan [Department of General Studies, Physics Group, Jubail University College, Royal Commission for Jubail, Jubail 10074 (Saudi Arabia); Song, Il-Seok; Kim, Jin-Soo; Baek, Byung-Joon [Semiconductor Materials Process Laboratory, School of Advanced Materials Engineering, Research Center for Advanced Materials Development, Chonbuk National University, Deokjin-Dong 664-14, Jeonju 561-756 (Korea, Republic of); Lee, Cheul-Ro, E-mail: crlee7@jbnu.ac.kr [Semiconductor Materials Process Laboratory, School of Advanced Materials Engineering, Research Center for Advanced Materials Development, Chonbuk National University, Deokjin-Dong 664-14, Jeonju 561-756 (Korea, Republic of)

    2015-06-05

    Highlights: • Se interlayer is deposited between the CuGa and CuIn/In/Mo/STS stacked layer. • Both CIG precursor layers were selenized at 500 °C for 1 h. • SIMS depth profile shows that Ga distribution is uniform by Se interlayer. • The efficiency was improved for the CIGS solar cell by Se interlayer. - Abstract: A CIGS absorber layer with high gallium contents in the space-charge region can reduce the carrier recombination and improve the open circuit voltage V{sub oc}. Therefore, controlling Ga grading on top of CIGS thin film solar cells is the main objective of this experiment. To reduce Selenium (Se) vacancy, it is important that the diffusion of Ga elements into Se vacancy between Mo back contact and CIGS absorption layer would be controlled. In order to reduce Se vacancy and confirm Ga inter-diffusion, two CIGS solar cells were fabricated by converting CIG precursor with and without Se interlayer. The copper-indium metallic precursors were fabricated corresponding to the sequence CuIn/In/Mo/STS on stainless steel (STS) substrates by sequential direct current magnetron sputtering while Se layer was evaporated by rapid thermal annealing (RTA) system to obtain a Se/CuIn/In/Mo/STS stack. CuGa precursor layer was also fabricated on the Se/CuIn/In/Mo/STS stack. Finally, both CuGa/Se/CuIn/In/Mo/STS and CuGa/CuIn/In/Mo/STS stacks were selenized at 500 °C for 1 h. It was clearly observed from the secondary ion mass spectroscopy (SIMS) and X-ray diffraction (XRD) that there was a change between the fabricated CIGS absorption layers and the amount of Ga elements. Furthermore, the Ga elements gradually decreased from the top to the bottom layer of the CIGS absorption layer. We also discussed the effect of Se interlayer in the CIGS absorption layer and its influence on the solar cell’s performance.

  13. Se interlayer in CIGS absorption layer for solar cell devices

    International Nuclear Information System (INIS)

    Lee, Seung-Kyu; Sim, Jae-Kwan; Kissinger, N.J. Suthan; Song, Il-Seok; Kim, Jin-Soo; Baek, Byung-Joon; Lee, Cheul-Ro

    2015-01-01

    Highlights: • Se interlayer is deposited between the CuGa and CuIn/In/Mo/STS stacked layer. • Both CIG precursor layers were selenized at 500 °C for 1 h. • SIMS depth profile shows that Ga distribution is uniform by Se interlayer. • The efficiency was improved for the CIGS solar cell by Se interlayer. - Abstract: A CIGS absorber layer with high gallium contents in the space-charge region can reduce the carrier recombination and improve the open circuit voltage V oc . Therefore, controlling Ga grading on top of CIGS thin film solar cells is the main objective of this experiment. To reduce Selenium (Se) vacancy, it is important that the diffusion of Ga elements into Se vacancy between Mo back contact and CIGS absorption layer would be controlled. In order to reduce Se vacancy and confirm Ga inter-diffusion, two CIGS solar cells were fabricated by converting CIG precursor with and without Se interlayer. The copper-indium metallic precursors were fabricated corresponding to the sequence CuIn/In/Mo/STS on stainless steel (STS) substrates by sequential direct current magnetron sputtering while Se layer was evaporated by rapid thermal annealing (RTA) system to obtain a Se/CuIn/In/Mo/STS stack. CuGa precursor layer was also fabricated on the Se/CuIn/In/Mo/STS stack. Finally, both CuGa/Se/CuIn/In/Mo/STS and CuGa/CuIn/In/Mo/STS stacks were selenized at 500 °C for 1 h. It was clearly observed from the secondary ion mass spectroscopy (SIMS) and X-ray diffraction (XRD) that there was a change between the fabricated CIGS absorption layers and the amount of Ga elements. Furthermore, the Ga elements gradually decreased from the top to the bottom layer of the CIGS absorption layer. We also discussed the effect of Se interlayer in the CIGS absorption layer and its influence on the solar cell’s performance

  14. Order-disorder phase transitions in the two-dimensional semiconducting transition metal dichalcogenide alloys Mo1−xWxX2 (X = S, Se, and Te)

    KAUST Repository

    Gan, Liyong

    2014-10-21

    A combination of density functional theory, an empirical model, and Monte Carlo simulations is used to shed light on the evolution of the atomic distribution in the two-dimensional semiconducting transition metal dichalcogenide alloys Mo1−xWxX2 (X = S, Se, and Te) as a function of the W concentration and temperature. Both random and ordered phases are discovered and the origin of the phase transitions is clarified. While the empirical model predicts at x = 1/3 and 2/3 ordered alloys, Monte Carlo simulations suggest that they only exist at low temperature due to a small energetic preference of Mo-X-W over Mo-X-Mo and W-X-W interactions, explaining the experimental observation of random alloy Mo1−xWxS2. Negative formation energies point to a high miscibility. Tunability of the band edges and band gaps by alteration of the W concentration gives rise to a broad range of applications.

  15. Order-disorder phase transitions in the two-dimensional semiconducting transition metal dichalcogenide alloys Mo1−xWxX2 (X = S, Se, and Te)

    KAUST Repository

    Gan, Liyong; Zhang, Qingyun; Zhao, Yu-Jun; Cheng, Yingchun; Schwingenschlö gl, Udo

    2014-01-01

    A combination of density functional theory, an empirical model, and Monte Carlo simulations is used to shed light on the evolution of the atomic distribution in the two-dimensional semiconducting transition metal dichalcogenide alloys Mo1−xWxX2 (X = S, Se, and Te) as a function of the W concentration and temperature. Both random and ordered phases are discovered and the origin of the phase transitions is clarified. While the empirical model predicts at x = 1/3 and 2/3 ordered alloys, Monte Carlo simulations suggest that they only exist at low temperature due to a small energetic preference of Mo-X-W over Mo-X-Mo and W-X-W interactions, explaining the experimental observation of random alloy Mo1−xWxS2. Negative formation energies point to a high miscibility. Tunability of the band edges and band gaps by alteration of the W concentration gives rise to a broad range of applications.

  16. Adsorption of oxyanions of As, B, Cr, Mo and Se from coal fly ash leachates using Al3+/Fe3+modified bentonite clay

    CSIR Research Space (South Africa)

    Vhahangwele, M

    2013-01-01

    Full Text Available ponds. On disposal, coal fly ash leaches out toxic chemical species on contact with the aqueous media hence posing hazardous effects to the aquatic and terrestrial environment. Of prime concern are Oxyanionic species such as As, B, Cr, Mo and Se...

  17. Comparison of Cu(In, Ga)Se{sub 2} thin films deposited on different preferred oriented Mo back contact by RF sputtering from a quaternary target

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Jing [Sichuan University, College of Materials Science and Engineering, Chengdu (China); Solar Energy Research Institute, Yunnan Normal University, Education Ministry Key Laboratory of Renewable Energy Advanced Materials and Manufacturing Technology, Kunming (China); Peng, Lianqin; Chen, Jinwei; Wang, Gang; Wang, Xueqin; Kang, Hong; Wang, Ruilin [Sichuan University, College of Materials Science and Engineering, Chengdu (China)

    2014-09-15

    The Cu(In, Ga)Se{sub 2} (CIGS) thin films were deposited on bare glass and DC sputtered preferential oriented Mo-coated glass by RF sputtering from a single quaternary target. The structural and morphological properties of the films were characterized by X-ray diffraction (XRD), Raman spectroscope, energy dispersive X-ray spectrometer (EDS) and atomic force microscope (AFM). Preferred orientation of the Mo back contact was tuned between (110) and (211) plane by controlling the thickness. All the deposited CIGS thin films show (112) preferred oriented chalcopyrite structures. The films prepared on Mo-coated glass show higher quality crystallinity, better stoichiometry composition and more smooth surface morphology. Especially, the film on (211) oriented Mo-coated glass with the best integrated performance is expected to be a candidate absorber for high-efficiency CIGS solar cell device. (orig.)

  18. Chemical vapor deposition and electric characterization of perovskite oxides LaMO3 (M=Co, Fe, Cr and Mn) thin films

    International Nuclear Information System (INIS)

    Ngamou, Patrick Herve Tchoua; Bahlawane, Naoufal

    2009-01-01

    Oxides with a perovskite structure are important functional materials often used for the development of modern devices. In view of extending their applicability, it is necessary to efficiently control their growth as thin films using technologically relevant synthesis methods. Pulsed spray evaporation CVD was used to grow several perovskite-type oxides on planar silicon substrates at temperatures ranging from 500 to 700 deg. C. The optimization of the process control parameters allows the attainment of the perovskite structure as a single phase. The electrical characterization using the temperature-dependent conductivity and thermopower indicates the p-type conduction of the grown films and shows a decreasing concentration of the charge carrier, mobility and band gap energy in the sequence LaCoO 3 >LaMnO 3 >LaCrO 3 >LaFeO 3 . The investigation of the electric properties of the obtained perovskite thin films shows the versatility of CVD as a method for the development of innovative devices. - Graphical abstract: We report a single step deposition of perovskite thin films LaMO 3 (M: Co, Mn, Cr, Fe) using pulsed spray evaporation chemical vapor deposition. Electrical and thermopower properties, similar to these of bulk materials, could promote the development of modern thermoelectric devices based on thin films technology.

  19. Nickel and Copper-Free Sintered Structural Steels Containing Mn, Cr, Si, and Mo Developed for High Performance Applications

    Directory of Open Access Journals (Sweden)

    Cias A.

    2017-03-01

    Full Text Available In an attempt to study the sinterability of potential high-strength nickel-free sintered structural steels containing Mn, Cr, Si and Mo compacts were prepared based on sponge and water atomised iron powders and on Astaloy prealloyed powders. To these were admixed ferromanganese, ferroslicon, and graphite. The samples were sintered at temperatures 1120 and 1250°C in laboratory tube furnaces in hydrogen, hydrogen-nitrogen atmospheres with dew points better than -60°C or in nitrogen in a semiclosed container in a local microatmosphere. After sintering the samples were slowly cooled or sinterhardened. Generally resultant microstructures were inhomogeneous, consisted of pearlite/ bainite/martensite, but were characterised by an absence of oxide networks. Sintering studies performed over a range of compositions have shown that superior strength, ranging beyond 900 MPa, along with reasonable tensile elongation, can be achieved with these new steels.

  20. Comentarios al dossier“¿Cómo se piensa lo ‘queer’ en América Latina”?

    Directory of Open Access Journals (Sweden)

    Edgar Vega Suriaga

    2011-05-01

    Full Text Available A partir del dossier de Íconos, 39, ¿Cómo se piensa lo ‘queer’ en América Latina?, este artículo trabajasobre los puntos centrales y las interrogantes que dan de sí cada uno de los artículos que locomponen. Destaca la crítica a la masculinidad hegemónica desde una noción de la alteridad enla que convergen las categorías de clase, etnia, género y edad. A medida que reflexiona sobre estospuntos, repasa cada uno de los artículos contextualizándolos en la crítica radical al sistema heteronormativo.

  1. Geochemistry of the Nsuta Mn deposit in Ghana: Implications for the Paleoproterozoic atmosphere and ocean chemistry

    Science.gov (United States)

    Goto, K. T.; Ito, T.; Suzuki, K.; Kashiwabara, T.; Takaya, Y.; Shimoda, G.; Nozaki, T.; Kiyokawa, S.; Tetteh, G. M.; Nyame, F. K.

    2013-12-01

    Oxygenation of the atmosphere and oceans has influenced the evolution of ocean chemistry and diversification of early life. A number of large manganese (Mn) deposits are distributed in the Paleoproterozoic sedimentary successions that were formed during the great oxidation event (GOE) around 2.4-2.2 Ga (Meynard, 2010). Due to the high redox potential of Mn, occurrences of Mn deposits have been regarded as important evidence for a highly oxidized environment during the Paleoproterozoic (Kirschvink et al., 2000). Furthermore, because Mn oxides strongly adsorb various elements, including bioessential elements such as Mo, formation of large Mn deposits may have affected the seawater chemical composition and ecology during the Paleoproterozoic. However, the genesis of each Mn deposit is poorly constrained, and the relationships among the formation of Mn deposits, the evolution of atmospheric and ocean chemistry, and the diversification of early life are still ambiguous. In this study, we report the Re-Os isotope compositions, rare earth element (REE) compositions, and abundance of manganophile elements in the Mn carbonate ore and host sedimentary rock samples collected from the Nsuta Mn deposit of the Birimian Supergroup, Ghana. The Nsuta deposit is one of the largest Paleoproterozoic Mn deposits, although its genesis remains controversial (Melcher et al., 1995; Mucke et al., 1999). The composite Re-Os isochron age (2149 × 130 Ma) of the Mn carbonate and sedimentary rock samples was consistent with the depositional age of the sedimentary rocks (~2.2 Ga) presumed from the U-Pb zircon age of volcanic rocks (Hirdes and Davis, 1998), suggesting that the timing of Mn ore deposition was almost equivalent to the host rock sedimentation. The PAAS-normalized REE pattern showed a positive Eu anomaly in all samples and a positive Ce anomaly only in the Mn carbonate ore. These REE patterns indicate the possible contribution of Eu-enriched fluids derived from hydrothermal activity

  2. Characterization of the interaction layer in diffusion couples U-Mo-Zr/Al and U-Mo-Zr/Al-A356 at 550 C degrees; Caracterizacion de la zona de interaccion en pares de difusion a 550 grados C U-Mo-Zr/Al y U-Mo-Zr/Al-A356

    Energy Technology Data Exchange (ETDEWEB)

    Komar Varela, Carolina; Arico, Sergio; Mirandou, Marcela; Balart, Silvia; Gribaudo, Luis [Comision Nacional de Energia Atomica, General San Martin (Argentina). Dept. de Materiales; com, carolinakomar@gmail

    2007-07-01

    Out-of-pile diffusion experiments were performed between U-7 wt.% Mo-1 wt.% Zr and Al or Al A356 (7,1 wt.% Si) at 550 C degrees. In this work morphological characterization and phase identification on both interaction layers are presented. They were carried out by the use of different techniques: optical and scanning electron microscopy, X-ray diffraction and WDS microanalysis. In the interaction layer U-7 wt.% Mo-1 wt.% Zr/Al, the phases UAl{sub 3}, UAl{sub 4}, Al{sub 20}Mo{sub 2}U and Al{sub 43}Mo{sub 4}U{sub 6} were identified. Similar results in the interaction layer of the U-7 % Mo/Al at 580 C degrees were previously obtained. In the interaction layer U-7 wt.% Mo-1 wt.% Zr/Al A356, the phases U(Al,Si){sub 3} with 25 at.% Si and Si{sub 5}U{sub 3} were identified. This last phase, with a higher Si concentration, was identified with X-ray diffraction synchrotron radiation performed at the National Synchrotron Light Laboratory, Campinas, Brazil. (author) [Spanish] Se realizaron experiencias fuera de reactor en pares de difusion quimica U-7 % Mo-1 % Zr/Al y U-7 % Mo-1 % Zr/Al A356. En este trabajo se presentan los resultados de la caracterizacion morfologica e identificacion de fases presentes en la zona de interaccion que se forma al ser sometidos a un tratamiento isotermico de 1,5 h a 550 grados C. Las tecnicas utilizadas fueron: microscopia optica y electronica de barrido, difraccion de rayos X y microanalisis cuantitativo por sonda electronica. En la zona de interaccion correspondiente al par U-7 % Mo-1 % Zr/Al se identificaron las fases UAl{sub 3}, UAl{sub 4}, Al{sub 20}Mo{sub 2}U y Al{sub 43}Mo{sub 4}U{sub 6}. Estas cuatro fases fueron identificadas en pares U-7 % Mo/Al a 580 grados C en trabajos anteriores. En la zona de interaccion correspondiente al par U-7 % Mo-1 % Zr/Al A356 se identificaron las fases U(Al,Si){sub 3} (con una concentracion de 25 %at.Si) y Si{sub 5}U{sub 3}. Este compuesto rico en Si solo pudo ser identificado mediante la utilizacion de

  3. Formation of stable and metastable phases in reciprocal systems PbSe + MI2 = MSe + PbI2 (M = Hg, Mn, Sn)

    International Nuclear Information System (INIS)

    Odin, I.N.; Grin'ko, V.V.; Kozlovskij, V.F.; Safronov, E.V.; Gapanovich, M.V.

    2004-01-01

    Using data of differential thermal, X-ray phase and microstructural analyses, phase diagrams of reciprocal systems PbSe + MI 2 = MSe + PbI 2 (M=Hg (1), Mn (2), Sn (3)) were constructed. It was ascertained that the HgSe-PbI 2 diagonal in system 1 is stable. Transformations leading to crystallization of metastable ternary compound formed in the system PbSe-PbI 2 and metastable polytypes of lead iodide in systems 1 and 2 in the range of temperatures from 620 to 685 K were studied. New intermediate metastable phases in systems 1, 2 and 3 were prepared by melt quenching. Crystal lattice parameters of the phases crystallizing in the CdCl 2 structural type were defined [ru

  4. [Determination of Al, Be, Cd, Co, Cr, Mn, Ni, Pb, Se and Tl in whole blood by atomic absorption spectrometry without preliminary sample digestion].

    Science.gov (United States)

    Ivanenko, N B; Ivanenko, A A; Solov'ev, N D; Navolotskiĭ, D V; Pavlova, O V; Ganeev, A A

    2014-01-01

    Methods of whole blood trace element determination by Graphite furnace atomic absorption spectrometry (in the variant of Zeeman's modulation polarization spectrometry) have been proposed. They do not require preliminary sample digestion. Furnace programs, modifiers and blood dilution factors were optimized. Seronorm™ human whole blood reference materials were used for validation. Dynamic ranges (for undiluted blood samples) were: Al 8 ¸ 210 мg/L; Be 0.3 ¸ 50 мg/L; Cd 0.2 ¸ 75 мg/L; Сo 5 ¸ 350 мg/L; Cr 10 ¸ 100 мg/L; Mn 6 ¸ 250 мg/L; Ni 10 ¸ 350 мg/L; Pb 3 ¸ 240 мg/L; Se 10 ¸ 500 мg/L; Tl 2 ¸ 600 мg/L. Precision (RSD) for the middle of dynamic range ranged from 5% for Mn to 11 for Se.

  5. Hydrothermal synthesis and crystal structure of a new molybdenum oxide compound with manganese-o-phen subunit: [Mn(o-phen)(H2O)MoO4]·H2O (o-phen=o-phenanthroline)

    International Nuclear Information System (INIS)

    Zhang Quanzheng; Lu Canzhong; Yang Wenbin; Chen Shumei; Yu Yaqin; He Xiang; Yan Ying; Liu Jiuhui; Xu Xinjiang; Xia Changkun; Wu Xiaoyuan; Chen Lijuan

    2004-01-01

    A new one-dimensional molybdenum oxide compound with manganese-o-phen subunit: [Mn(o-phen)(H 2 O)MoO 4 ]·H 2 O (1) (o-phen=o-phenanthroline) was synthesized by the hydrothermal reaction of Na 2 MoO 4 ·2H 2 O, MnSO 4 ·H 2 O, oxalic acid, o-phenanthroline (o-phen) and water. Its structure was determined by elemental analyses, ESR spectrum, TG analysis, IR spectrum and single-crystal X-ray diffraction. Compound 1 crystallizes in triclinic system, space group P-1 with a=7.0401(2) A, b=10.4498(2) A, c=10.5720(2) A, α=73.26(7) deg., β=83.34(8) deg., γ=77.33(9) deg., V=725.5089(0) A 3 , Z=2, and R 1 =0.0322 for 2337 observed reflections. Compound 1 exhibits one-dimensional chain structure. The chains are linked up via hydrogen bonding to 2D layers, which are further assembled through π-π stacking interactions to a 3D supermolecular structure

  6. Bandwidth and Electron Correlation-Tuned Superconductivity in Rb<mn>0.8mn>Fe>2mn> stretchy='false'>(mo>Se>1mn>->zSz<mo stretchy='false'>)mo>>2mn>

    Energy Technology Data Exchange (ETDEWEB)

    Yi, M.; Wang, Meng; Kemper, A. F.; Mo, S. -K.; Hussain, Z.; Bourret-Courchesne, E.; Lanzara, A.; Hashimoto, M.; Lu, D. H.; Shen, Z. -X.; Birgeneau, R. J.

    2015-12-01

    We present a systematic angle-resolved photoemission spectroscopy study of the substitution dependence of the electronic structure of Rb0.8Fe2(Se1-zSz)2 (z=0, 0.5, 1), where superconductivity is continuously suppressed into a metallic phase. Going from the nonsuperconducting Rb0.8Fe2S2 to superconducting Rb0.8Fe2Se2, we observe little change of the Fermi surface topology, but a reduction of the overall bandwidth by a factor of 2. Hence, for these heavily electron-doped iron chalcogenides, we have identified electron correlation as explicitly manifested in the quasiparticle bandwidth to be the important tuning parameter for superconductivity, and that moderate correlation is essential to achieving high TC.

  7. Improved performance of CdS/CdSe quantum dot-sensitized solar cells using Mn-doped PbS quantum dots as a catalyst in the counter electrode

    International Nuclear Information System (INIS)

    Kim, Byung-Man; Son, Min-Kyu; Kim, Soo-Kyoung; Hong, Na-Yeong; Park, Songyi; Jeong, Myeong-Soo; Seo, Hyunwoong; Prabakar, Kandasamy; Kim, Hee-Je

    2014-01-01

    Highlights: • PbS QDs synthesized using the SILAR method act not only as the electrochemical catalysts but as donors providing additional electrons under illumination. • The electrochemical and optical properties of the PbS QDs were enhanced considerably after Mn 2+ doping. • The electron supply from the counter electrode was significantly activated by Mn 2+ doping, improving the performance of QDSSC. - Abstract: This study reports the enhanced catalytic ability of Mn-doped PbS QDs synthesized using a successive ionic layer adsorption and reaction (SILAR) method for quantum dot-sensitized solar cells (QDSSCs). Electrochemical and optical analysis of each material showed that the catalytic ability of the PbS electrode was improved significantly by Mn 2+ doping. Two factors can explain this behavior. The first is that intentional impurities have an impact on the structure of the host material, such as increases in surface roughness. The other is that dopants create new energy states that delay the exciton recombination time and allow charge separation to be activated. As a result, the photoelectron supply from the counter electrode is accelerated, resulting in vigorous redox reactions at the polysulfide electrolyte. The performance of the CdS/CdSe QDSSC using a Mn-doped PbS counter electrode was compared with those using the Pt and PbS counter electrodes. Finally, a power conversion efficiency of 3.61% was achieved with the Mn-doped PbS counter electrode (V OC = 0.61 V, J SC = 11.67 mA cm −2 , FF = 0.51) under one sun illumination (100 mW cm −2 ), which is ∼40% higher than that of CdS/CdSe QDSSCs with the bare PbS counter electrode

  8. A study of element migration in the Maqarin site (Jordan) by the means of column experiments: II. trace elements (Cr, Se, Mo, Re)

    International Nuclear Information System (INIS)

    Trotignon, L.; Bienvenu, P.; Provitina, O.; Rose, J.; Khoury, H.; Trocellier, P.; Mercier, F.; Raimbault, L.

    2005-01-01

    Full text of publication follows: The site of Maqarin (Jordan), in which natural cements occur as a result of the combustion metamorphism of a bio-micrite, is studied since 1989 as a natural analogue for the long term evolution of a cementitious repository environment [1]. Several trace elements of interest (Cr, Se, Mo, Re) are mobilized on this site by percolating groundwaters and migrate along high pH plumes. Laboratory scale column experiments were conducted in which crushed materials (cement, bio-micrite) collected on site were submitted to leaching by deionized water or Ca(OH) 2 equilibrated solutions. The evolution of Cr, Mo, Se and Re was monitored in leachates during the experiments. Characterizations of the solid phase using several techniques were also conducted in order to locate these elements in the mineral phases. Comparison of experimental data with records of trace element concentration in Maqarin groundwaters gives some insight on Re, Cr, Se and Mo sources and sinks in this environment. Both the imprint of the past combustion event and present day redox transformations explain several features of the datasets. However, due to the high complexity of the cements, in which trace elements are often distributed among several mineral phases, it is presently not possible to link in a straightforward way individual mineral dissolution processes and trace element signals in waters. [1] Khoury H. N., Salameh E., Clark I. D., Fritz P., Bajjali W., Milodowski A. E., Cave M. R. and Alexander W. R. 1992. A natural analogue of high pH cement pore waters from the Maqarin area of northern Jordan. I: Introduction to the site. J. Geochem. Explor. 46: 117-132. (authors)

  9. Electronic and magnetic properties of 3d-metal trioxides superhalogen cluster-doped monolayer MoS2: A first-principles study

    International Nuclear Information System (INIS)

    Li, Dan; Niu, Yuan; Zhao, Hongmin; Liang, Chunjun; He, Zhiqun

    2014-01-01

    Utilizing first-principle calculations, the structural, electronic, and magnetic properties of monolayer MoS 2 doped with 3d transition-metal (TM) atoms and 3d-metal trioxides (TMO 3 ) superhalogen clusters are investigated. 3d-metal TMO 3 superhalogen cluster-doped monolayers MoS 2 almost have negative formation energies except CoO 3 and NiO 3 doped monolayer MoS 2 , which are much lower than those of 3d TM-doped structures. 3d-metal TMO 3 superhalogen clusters are more easily embedded in monolayer MoS 2 than 3d-metal atoms. MnO 3 , FeO 3 , CoO 3 , and NiO 3 incorporated into monolayer MoS 2 are magnetic, and the total magnetic moments are approximately 1.0, 2.0, 3.0, and 4.0 μB per supercell, respectively. MnO 3 and FeO 3 incorporated into monolayer MoS 2 become semiconductors, whereas CoO 3 and NiO 3 incorporated into monolayer MoS 2 become half-metallic. Our studies demonstrate that the half-metallic ferromagnetic nature of 3d-metal TMO 3 superhalogen clusters-doped monolayer MoS 2 has a great potential for MoS 2 -based spintronic device applications. -- Highlights: •TMO 3 superhalogen clusters incorporated into monolayer MoS 2 were investigated. •TMO 3 doped structures have much lower formation energies than TM doped structures. •TMO 3 cluster-doped MoS 2 are thermodynamically favored. •Significant charge transfers between O atoms and Mo atoms in TMO 3 doped structures. •MnO 3 , FeO 3 , CoO 3 , and NiO 3 incorporated into monolayer MoS 2 are magnetic.

  10. Surfactant-thermal syntheses, structures, and magnetic properties of Mn-Ge-sulfides/selenides

    KAUST Repository

    Zhang, Guodong

    2014-10-06

    Although either surfactants or amines have been investigated to direct the crystal growth of metal chalcogenides, the synergic effect of organic amines and surfactants to control the crystal growth has not been explored. In this report, several organic bases (hydrazine monohydrate, ethylenediamine (en), 1,2-propanediamine (1,2-dap), and 1,3-propanediamine (1,3-dap)) have been employed as structure-directing agents (SDAs) to prepare four novel chalcogenides (Mn3Ge2S7(NH3)4 (1), [Mn(en)2(H2O)][Mn(en)2MnGe3Se9] (2), (1,2-dapH)2{[Mn(1,2-dap)2]Ge2Se7} (3), and (1,3-dapH)(puH)MnGeSe4(4) (pu = propyleneurea) under surfactant media (PEG-400). These as-prepared new crystalline materials provide diverse metal coordination geometries, including MnS3N tetrahedra, MnGe2Se7 trimer, and MnGe3Se10 T2 cluster. Compounds 1-3 have been fully characterized by single-crystal X-ray diffraction (XRD), powder XRD, UV-vis spectra, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Moreover, magnetic measurements for compound 1 showed an obvious antiferromagnetic transition at ∼9 K. Our research not only enriches the structural chemistry of the transitional-metal/14/16 chalcogenides but also allows us to better understand the synergic effect of organic amines and surfactants on the crystallization of metal chalcogenides.

  11. EPR and FTIR spectroscopic studies of MO-Al2O3-Bi2O3-B2O3-MnO2(M = Pb, Zn and Cd) glasses

    Science.gov (United States)

    Lalitha Phani, A. V.; Sekhar, K. Chandra; Chakradhar, R. P. S.; Narasimha Chary, M.; Shareefuddin, Md

    2018-03-01

    Glasses of the system (30-x)MO-xAl2O3-15Bi2O3-54.5B2O3-0.5MnO2 [M = Pb, Zn & Cd] (x = 0, 5, 10 & 15 mol%) were prepared by the normal melt quenching method. The amorphous nature of the prepared glasses was confirmed by the XRD studies. The EPR and FTIR studies were carried out at room temperature (RT). The EPR spectra exhibited three resonance signals at g ≈ 2.0 with a hyperfine structure, an absorption around g = 4.3 and a distinct shoulder at g = 3.3. Deconvoluted spectra were drawn for g ≈ 2.0 to resolve the six hyperfine lines. The electron paramagnetic resonance signal at g ≈ 2.0 indicates that the Mn2+ ions are in nearly perfectly octahedral symmetry. The low field signals at g = 3.3 and g = 4.3 are attributed to the Mn2+ ion which are in distorted rhombic symmetries. The hyperfine (HF) splitting constant (A) values suggested that the bonding between Mn2+ ions and its ligands is ionic in nature. The presence of BO3 and BO4 borate units, metal oxide cation units, Mn2+ and Bi-O bond vibrations in BiO3 units were noticed from the FTIR spectra.

  12. Oxidative stress by Se-deficiency and dynamics of biotrace elements

    International Nuclear Information System (INIS)

    Sakuma, Yasunobu; Tsuyuki, Satoshi; Nagayama, Atsuko; Matsuoka, Keisuke; Honda, Chikako; Endo, Kazutoyo

    2006-01-01

    Metal ions such as Mn, Fe, Cu, Zn, Se are located at the center of the antioxidants in biological systems. Selenium (Se) is contained in GSH-Px (glutathione peroxidase), one of the antioxidants, and is related to various other metal ions to keep redox balance in organism. In the present study, Mn contents in cell fractions of liver homogenates of Se-deficient rat, and control (normal) rats were determined by means of INAA. The results showed that the Mn contents in microsomal fraction of male Se-deficient rats were greater than the control for male rats, and that the trend was different for female rats. The results were presented together with the results of SOD and TBARS. (author)

  13. Polycrystalline Mn-alloyed indium tin oxide films

    International Nuclear Information System (INIS)

    Scarlat, Camelia; Schmidt, Heidemarie; Xu, Qingyu; Vinnichenko, Mykola; Kolitsch, Andreas; Helm, Manfred; Iacomi, Felicia

    2008-01-01

    Magnetic ITO films are interesting for integrating ITO into magneto-optoelectronic devices. We investigated n-conducting indium tin oxide (ITO) films with different Mn doping concentration which have been grown by chemical vapour deposition using targets with the atomic ratio In:Sn:Mn=122:12:0,114:12:7, and 109:12:13. The average film roughness ranges between 30 and 50 nm and XRD patterns revealed a polycrystalline structure. Magnetotransport measurements revealed negative magnetoresistance for all the samples, but high field positive MR can be clearly observed at 5 K with increasing Mn doping concentration. Spectroscopic ellipsometry (SE) has been used to prove the existence of midgap states in the Mn-alloyed ITO films revealing a transmittance less than 80%. A reasonable model for the ca. 250 nm thick Mn-alloyed ITO films has been developed to extract optical constants from SE data below 3 eV. Depending on the Mn content, a Lorentz oscillator placed between 1 and 2 eV was used to model optical absorption below the band gap

  14. The synthesis and photocatalytic activity of ZnSe microspheres

    International Nuclear Information System (INIS)

    Cao Huaqiang; Xiao Yujiang; Zhang Sichun

    2011-01-01

    This paper reports the synthesis of semiconductor ZnSe microspheres composed of nanoparticles via a solvothermal route between the organic molecule selenophene (C 4 H 4 Se) and ZnCl 2 without adding any surfactant. The ZnSe microspheres were characterized by x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), specific surface area measurement, and photoluminescence (PL) spectra. A strong and broad blue PL emission at 443 nm in wavelength (∼2.79 eV in photon energy) is attributed to the near-band-edge (NBE) emission of ZnSe, while the 530 nm peak is a defect-related (DL) emission. The photocatalytic activity of the as-prepared ZnSe microspheres was evaluated by photodegradation of methyl orange (MO) dye under ultraviolet (UV) light and visible light irradiation. The degradations of MO reach 94% or 95.1%, close to 100%, in the presence of the as-synthesized ZnSe microspheres or commercial ZnSe powder after 7 or 10 h under UV irradiation, respectively. Meanwhile the degradations of MO reach 94.3% or 60.6% in the presence of the as-synthesized ZnSe microspheres or commercial ZnSe powder after 12 h, respectively. The degradation rate of ZnSe microspheres is twice that of ZnSe commercial powder under UV light irradiation, and three times under visible light irradiation. The degradation process of MO dye on ZnSe microspheres under UV or visible light is also discussed.

  15. The Faceted Discrete Growth and Phase Differentiation During the Directional Solidification of 20SiMnMo5 Steel

    Science.gov (United States)

    Ma, Xiaoping; Li, Dianzhong

    2018-07-01

    The microstructures, segregation and cooling curve were investigated in the directional solidification of 20SiMnMo5 steel. The typical characteristic of faceted growth is identified. The microstructures within the single cellular and within the single dendritic arm, together with the contradictive segregation distribution against the cooling curve, verify the discrete crystal growth in multi-scales. Not only the single cellular/dendritic arm but also the single martensite zone within the single cellular/dendritic arm is produced by the discrete growth. In the viewpoint of segregation, the basic domain following continuous growth has not been revealed. Along with the multi-scale faceted discrete growth, the phase differentiation happens for both the solid and liquid. The differentiated liquid phases appear and evolve with different sizes, positions, compositions and durations. The physical mechanism for the faceted discrete growth is qualitatively established based on the nucleation of new faceted steps induced by the composition gradient and temperature gradient.

  16. The Faceted Discrete Growth and Phase Differentiation During the Directional Solidification of 20SiMnMo5 Steel

    Science.gov (United States)

    Ma, Xiaoping; Li, Dianzhong

    2018-03-01

    The microstructures, segregation and cooling curve were investigated in the directional solidification of 20SiMnMo5 steel. The typical characteristic of faceted growth is identified. The microstructures within the single cellular and within the single dendritic arm, together with the contradictive segregation distribution against the cooling curve, verify the discrete crystal growth in multi-scales. Not only the single cellular/dendritic arm but also the single martensite zone within the single cellular/dendritic arm is produced by the discrete growth. In the viewpoint of segregation, the basic domain following continuous growth has not been revealed. Along with the multi-scale faceted discrete growth, the phase differentiation happens for both the solid and liquid. The differentiated liquid phases appear and evolve with different sizes, positions, compositions and durations. The physical mechanism for the faceted discrete growth is qualitatively established based on the nucleation of new faceted steps induced by the composition gradient and temperature gradient.

  17. Large enhancement in photocurrent by Mn doping in CdSe/ZTO quantum dot sensitized solar cells.

    Science.gov (United States)

    Pimachev, Artem; Poudyal, Uma; Proshchenko, Vitaly; Wang, Wenyong; Dahnovsky, Yuri

    2016-09-29

    We find a large enhancement in the efficiency of CdSe quantum dot sensitized solar cells by doping with manganese. In the presence of Mn impurities in relatively small concentrations (2.3%) the photoelectric current increases by up to 190%. The average photocurrent enhancement is about 160%. This effect cannot be explained by a light absorption mechanism because the experimental and theoretical absorption spectra demonstrate that there is no change in the absorption coefficient in the presence of the Mn impurities. To explain such a large increase in the injection current we propose a tunneling mechanism of electron injection from the quantum dot LUMO state to the Zn 2 SnO 4 (ZTO) semiconductor photoanode. The calculated enhancement is approximately equal to 150% which is very close to the experimental average value of 160%. The relative discrepancy between the calculated and experimentally measured ratios of the IPCE currents is only 6.25%. For other mechanisms (such as electron trapping, etc.) the remaining 6.25% cannot explain the large change in the experimental IPCE. Thus we have indirectly proved that electron tunneling is the major mechanism of photocurrent enhancement. This work proposes a new approach for a significant improvement in the efficiency of quantum dot sensitized solar cells.

  18. Aspectos bibliográficos del TFG. Cómo citar y componer la bibliografía

    OpenAIRE

    García Folgado, Mª José; Rodríguez Gonzalo, Carmen

    2014-01-01

    Este capítulo intenta dar respuesta a una larga serie de preguntas que surgen en la redacción del trabajo de fin de grado (TFG): ¿cómo introducir en el texto las ideas y palabras de los autores consultados? ¿Cómo se citan las palabras de un autor citadas por otro trabajo? ¿Cómo plasmar todo lo que se ha leído? ¿Cómo incluirlo en la bibliografía? ¿Hay que poner lo que se ha leído, pero no se ha usado? ¿Cómo se citan las fuentes de red? ¿Qué hacer si la fuente consultada ti...

  19. Phase equilibrium in Rb2MoO4-AMoO4-Zr(MOO4)2 systems (A - bivalent elements)

    International Nuclear Information System (INIS)

    Ivanova, M.N.; Tsyrenova, G.D.; Bazarova, Zh.G.

    1993-01-01

    The Rb 2 MoO 4 -AMoO 4 -Zr(MoO 4 ) 2 systems, where A - bivalent elements, were investigated by solid phase reactions, x-ray and differntial thermal analysis methods. Formation of new ternary molybdates was determined. Phase relationships in the Rb 2 MoO 4 -MnMoO 4 -Zr(MoO 4 ) 2 system in subsolidus range (550 deg C) were studied using x-ray analysis data

  20. Ultrasensitive photoelectrochemical aptasensor for lead ion detection based on sensitization effect of CdTe QDs on MoS2-CdS:Mn nanocomposites by the formation of G-quadruplex structure.

    Science.gov (United States)

    Shi, Jian-Jun; Zhu, Jing-Chun; Zhao, Ming; Wang, Yan; Yang, Ping; He, Jie

    2018-06-01

    An ultrasensitive photoelectrochemical (PEC) aptasensor for lead ion (Pb 2+ ) detection was fabricated based on MoS 2 -CdS:Mn nanocomposites and sensitization effect of CdTe quantum dots (QDs). MoS 2 -CdS:Mn modified electrode was used as the PEC matrix for the immobilization of probe DNA (pDNA) labeled with CdTe QDs. Target DNA (tDNA) were hybridized with pDNA to made the QDs locate away from the electrode surface by the rod-like double helix. The detection of Pb 2+ was based on the conformational change of the pDNA to G-quadruplex structure in the presence of Pb 2+ , which made the labeled QDs move close to the electrode surface, leading to the generation of sensitization effect and evident increase of the photocurrent intensity. The linear range was 50 fM to 100 nM with a detection limit of 16.7 fM. The recoveries of the determination of Pb 2+ in real samples were in the range of 102.5-108.0%. This proposed PEC aptasensor provides a new sensing strategy for various heavy metal ions at ultralow levels. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Electrochemical activation of Li2MnO3 at elevated temperature investigated by in situ Raman microscopy

    International Nuclear Information System (INIS)

    Lanz, Patrick; Villevieille, Claire; Novák, Petr

    2013-01-01

    Layered-layered oxides of the type xLi 2 MnO 3 ·(1 − x)LiMO 2 (M = Mn, Ni, Co) have been postulated to contain Li 2 MnO 3 domains which, upon electrochemical activation, give rise to a characteristic potential plateau at 4.5 V vs. Li + /Li. To improve our understanding of the complex reaction mechanisms at play, we applied in situ Raman microscopy to investigate the constituent Li 2 MnO 3 . Li 2 MnO 3 synthesised via a two-step solid-state reaction was characterised by scanning electron microscopy and X-ray diffraction. Preliminary electrochemical tests and ex situ Raman microscopy showed the need for elevated temperatures to achieve activation. For the first time, in situ Raman microscopy (at 50 °C) confirmed the activation of Li 2 MnO 3 . The main signal at 615 cm −1 shifted to higher wavenumbers upon charging. After reaching 4.4 V vs. Li + /Li, this shift grew significantly, which is in good agreement with the onset of the potential plateau in both Li 2 MnO 3 and xLi 2 MnO 3 ·(1 − x)LiMO 2 , and is assigned to the partial formation of a spinel-like phase

  2. Molybdenum depletion around P-phases Ni-Cr-Mo-W weld metals

    International Nuclear Information System (INIS)

    Silva, Cleiton Carvalho; Miranda, Helio Cordeiro de; Farias, Jesualdo Pereira

    2010-01-01

    This work evaluated the local chemical composition in matrix/precipitate interface in a Ni-Cr-Mo-W alloy weld metals deposited on substrate of C-Mn steel. The microstructural characterization was carried out through optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The results had shown that the presence of secondary phases precipitates in the interdendritic region. Through SEM analysis were observed indications of depletion of Mo around these phases. These precipitates were identified as P-phase by TEM analysis. The Mo depletion indications were confirmed through EDS. The Mo depletion was a result of a reheating due to several welding heat cycles deposited to promote the coating layer. (author)

  3. Magnetic anisotropy of [Mo(CN)7]4- anions and fragments of cyano-bridged magnetic networks.

    Science.gov (United States)

    Chibotaru, Liviu F; Hendrickx, Marc F A; Clima, Sergiu; Larionova, Joulia; Ceulemans, Arnout

    2005-08-18

    Quantum chemistry calculations of CASSCF/CASPT2 level together with ligand field analysis are used for the investigation of magnetic anisotropy of [Mo(CN)7]4- complexes. We have considered three types of heptacyano environments: two ideal geometries, a pentagonal bipyramid and a capped trigonal prism, and the heptacyanomolybdate fragment of the cyano-bridged magnetic network K2[Mn(H2O)2]3[Mo(CN)7]2.6H2O. At all geometries the first excited Kramers doublet is found remarkably close to the ground one due to a small orbital energy gap in the ligand field spectrum, which ranges between a maximal value in the capped trigonal prism (800 cm(-1)) and zero in the pentagonal bipyramid. The small value of this gap explains (i) the axial form of the g tensor and (ii) the strong magnetic anisotropy even in strongly distorted complexes. Comparison with available experimental data for the g tensor of the mononuclear precursors reveals good agreement with the present calculations for the capped trigonal prismatic complex and a significant discrepancy for the pentagonal bipyramidal one. The calculations for the heptacyanomolybdate fragment of K2[Mn(H2O)2]3[Mo(CN)7]2.6H2O give g(perpendicular)/g(parallel) approximately 0.5 and the orientation of the local anisotropy axis close to the symmetry axis of an idealized pentagonal bipyramid. These findings are expected to be important for the understanding of the magnetism of anisotropic Mo(III)-Mn(II) cyano-bridged networks based on the [Mo(CN)7]4- building block.

  4. Strain tunable magnetic properties of 3d transition-metal ion doped monolayer MoS2: A first-principles study

    Science.gov (United States)

    Zhu, Yupeng; Liang, Xiao; Qin, Jun; Deng, Longjiang; Bi, Lei

    2018-05-01

    In this article, a systematic study on the magnetic properties and strain tunability of 3d transition metal ions (Mn, Fe, Co, Ni) doped MoS2 using first-principles calculations is performed. Antiferromagnetic coupling is observed between Mn, Fe ions and the nearest neighbor Mo ions; whereas ferromagnetic coupling is observed in Co and Ni systems. It is also shown that by applying biaxial tensile strain, a significant change of the magnetic moment is observed in all transition metal doped MoS2 materials with a strain threshold. The changes of total magnetic moment have different mechanisms for different doping systems including an abrupt change of the bond lengths, charge transfer and strain induced structural anisotropy. These results demonstrate applying strain as a promising method for tuning the magnetic properties in transition metal ion doped monolayer MoS2.

  5. Effect of the leaching of Ru-Se-Fe and Ru-Mo-Fe obtained by mechanical alloying on electrocatalytical behavior for the oxygen reduction reaction

    International Nuclear Information System (INIS)

    Ezeta, A.; Arce, E.M.; Solorza, O.; Gonzalez, R.G.; Dorantes, H.

    2009-01-01

    In the present work, Ru-Se-Fe and Ru-Mo-Fe alloyed nanoparticles were synthesized from high purity powders (Ru, Se and Mo) by means of the high-energy mechanical alloying. Fe was integrated to the alloys because of the erosion of the mill balls. The ORR electrocatalytic performance of the alloys (lixiviated or not) was evaluated in a rotating disc electrode (RDE) at room temperature. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for the structure characterization of the materials. Small-particle clusters with granular morphology and nanometric sizes were obtained in all the cases. According to the Tafel parameters from the RDE results, a first order ORR is present in both electrocatalytic systems through a 4e - global multielectron transference to form water: O 2 + 4H + + e - → H 2 O. The electrocatalytic activity showed that the mechanical alloying enabled to obtain nanoparticle electrocatalysts with good ORR performance. Lixiviation of the mechanical alloying powders not improves the catalytical responses.

  6. The Amounts of As, Au, Br, Cu, Fe, Mo, Se and Zn in Normal and Uraemic Human whole Blood. A. Comparison by Means of Neutron Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Brune, D; Samsahl, K [AB Atomenergi, Nykoeping (Sweden); Wester, P O [Dept. of Medicine, Karolinska Inst., Serafimerlasarettet, Stockholm (Sweden)

    1964-01-15

    Quantitative determination of the elements As, Au, Br, Cu, Fe, Mo, Se and Zn have been performed in normal and uraemic human whole blood by means of H{sub 2}SO{sub 4} - H-O- digestion, distillation and ion exchange, combined with gamma-spectrometric analysis. The uraemic blood was found to contain about 10 times as much As and twice as much Mo as did the normal blood. As regards Fe, the uraemic blood contained slightly less than the normal blood. For the other elements there were no detectable difference.

  7. Hyperfine interactions studies in perovskite oxides of the type LaMO3 (M = Fe, Cr, Mn and Co)

    International Nuclear Information System (INIS)

    Junqueira, Astrogildo de Carvalho

    2004-01-01

    ABO 3 -type perovskite oxides have ideal cubic structure and usually show distortions to the orthorhombic or rombohedric symmetry. The A and B siteshave 12-fold and 6-fold oxygen coordination, respectively. Distortions of thecubic structure give rise to new electric, structural and magnetic propertieswhich have great technological and scientific interests. Magnetic dipole and electric quadrupole hyperfine interaction measurements were obtained using 111 In -> 111 Cd , 181 Hf -> 181 Ta e 140 La -> 140 Ceradioactive nuclei substituting for the A or B sites via Perturbed Angulargamma-gamma Correlation technique (1-4) . LaMO 3 (M = Fe, Cr, Mn and Co)samples were prepared through the chemical route known as Sol-Gel techniqueand analyzed with x-ray diffraction. Both 111 In and 181 Hf nuclei wereintroduced in to the sample during the chemical procedure and the 140 Lawas obtained by irradiating with neutrons in the IPEN reactor the natural Lapresent in the samples. One of the aims of this work was the analysis of theElectric Field Gradient (EFG) in the A and B sites as function oftemperature, crystal structure or the electronic characteristic of thetransition metal in the B site. The temperature range of the measurements wasabout from 4 K to 1400 K. The experimental EFG showed to be dependent of thesite occupation and the nuclear probe used in the measurements. Spintransition phenomena were also observed in LaCoO 3 samples, which confirmed amodel used to interpret the spin properties in such compound.Crystallographic phase transition effects on the hyperfine parameters inperovskites where M = Fe, Cr and K4n were also analyzed. An additional aim ofthis work was to carry out measurements in the antiferromagnetic region ofthe systems with M = Fe, Cr and Mn using the three radioactive nuclei. Theresults for the magnetic interaction measurements showed a strong influenceof the substitutional sites in the supertransferred magnetic hyperfine fieldfor all the three probe nuclei

  8. Chromium-free conversion coatings based on inorganic salts (Zr/Ti/Mn/Mo) for aluminum alloys used in aircraft applications

    Energy Technology Data Exchange (ETDEWEB)

    Santa Coloma, P., E-mail: patricia.santacoloma@tecnalia.com [TECNALIA Research & Innovation, Parque Tecnológico de San Sebastián, Mikeletegi Pasealekua 2, E-20009 Donostia-San Sebastián, Gipuzkoa (Spain); Izagirre, U.; Belaustegi, Y.; Jorcin, J.B.; Cano, F.J. [TECNALIA Research & Innovation, Parque Tecnológico de San Sebastián, Mikeletegi Pasealekua 2, E-20009 Donostia-San Sebastián, Gipuzkoa (Spain); Lapeña, N. [Boeing Research & Technology Europe, S.L.U., Avenida Sur del Aeropuerto de Barajas 38, Building 4 – 3rd Floor, E-28042 Madrid (Spain)

    2015-08-01

    Highlights: • Chromium-free conversion coatings for corrosion protection of aluminum alloys. • Salt spray and potentiodynamic sweep tests to study the corrosion behavior. • Local deposits on Cu-rich intermetallic particles enhanced corrosion resistance. • Surface characterization to relate bath's composition and corrosion resistance. • Best corrosion protection with conversion baths without titanium salts. - Abstract: Novel chromium-free conversion coatings based on Zr/Ti/Mn/Mo compounds were developed at a pilot scale to improve the corrosion resistance of the AA2024-T3 and AA7075-T6 aluminum alloys for aircraft applications. The influence of the presence of Zr and Ti in the Zr/Ti/Mn/Mo conversion bath's formulation on the corrosion resistance of the coated alloys was investigated. The corrosion resistance provided by the conversion coatings was evaluated by salt spray exposure and potentiodynamic sweeps. Optical and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and atomic force microscopy (AFM) operating in the Kelvin Probe mode (SKPFM) were used to provide microstructural information of the coated samples that achieved the best results in the corrosion tests. The salt spray test evidenced the higher corrosion resistance of the coated samples compared to the bare surfaces for both alloys. The potentiodynamic tests showed that the corrosion current density decreased for coated AA7075-T6 and AA2024-T3 alloys, which indicated an obvious improvement of the corrosion resistance with all the processes for both alloys. Although the corrosion resistance of the coated samples appeared to be higher for the alloy AA7075-T6 than for the alloy AA2024-T3, both alloys achieved the best corrosion protection with the coatings deposited from conversion bath formulations containing no titanium salts. The microscopy analysis on the coated AA7075-T6 samples revealed that a local deposition of Zr compounds and, possibly, an

  9. Chromium-free conversion coatings based on inorganic salts (Zr/Ti/Mn/Mo) for aluminum alloys used in aircraft applications

    International Nuclear Information System (INIS)

    Santa Coloma, P.; Izagirre, U.; Belaustegi, Y.; Jorcin, J.B.; Cano, F.J.; Lapeña, N.

    2015-01-01

    Highlights: • Chromium-free conversion coatings for corrosion protection of aluminum alloys. • Salt spray and potentiodynamic sweep tests to study the corrosion behavior. • Local deposits on Cu-rich intermetallic particles enhanced corrosion resistance. • Surface characterization to relate bath's composition and corrosion resistance. • Best corrosion protection with conversion baths without titanium salts. - Abstract: Novel chromium-free conversion coatings based on Zr/Ti/Mn/Mo compounds were developed at a pilot scale to improve the corrosion resistance of the AA2024-T3 and AA7075-T6 aluminum alloys for aircraft applications. The influence of the presence of Zr and Ti in the Zr/Ti/Mn/Mo conversion bath's formulation on the corrosion resistance of the coated alloys was investigated. The corrosion resistance provided by the conversion coatings was evaluated by salt spray exposure and potentiodynamic sweeps. Optical and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and atomic force microscopy (AFM) operating in the Kelvin Probe mode (SKPFM) were used to provide microstructural information of the coated samples that achieved the best results in the corrosion tests. The salt spray test evidenced the higher corrosion resistance of the coated samples compared to the bare surfaces for both alloys. The potentiodynamic tests showed that the corrosion current density decreased for coated AA7075-T6 and AA2024-T3 alloys, which indicated an obvious improvement of the corrosion resistance with all the processes for both alloys. Although the corrosion resistance of the coated samples appeared to be higher for the alloy AA7075-T6 than for the alloy AA2024-T3, both alloys achieved the best corrosion protection with the coatings deposited from conversion bath formulations containing no titanium salts. The microscopy analysis on the coated AA7075-T6 samples revealed that a local deposition of Zr compounds and, possibly, an

  10. Precipitation behavior of the lower bainitic carbide in a medium-carbon steel containing Si, Mn and Mo

    International Nuclear Information System (INIS)

    Liu, J.; Luo, C.P.

    2006-01-01

    The fine microstructure, crystallographic features and ε-carbides precipitation behavior of lower bainite produced by isothermal transformation in a medium-carbon steel containing Si, Mn and Mo were investigated using transmission electronic microscopy. It was found that the microstructure produced by isothermal reaction at 320 deg. C was composed of a large amount of plate-like lower bainite with retained austenite embedded between the plates, and ε-carbides precipitated within them. Midrib and subunits were readily visible in the lower bainite plate. The bainite plate kept a G-T orientation relationship (OR) with the austenite. Selected area electron diffraction patterns of 'three phases in four variants' and analysis indicated that two variants of ε-carbides precipitated in a single bainitic ferrite plate. The two (or three) variants of ε-carbides can simultaneously keep a Jack OR with its 'bainite matrix', while keeping no fixed OR with the austenite. The crystallographic features of ε-carbides precipitated within the bainite were the same as those observed in tempered martensite. The results indicated that the bainitic transformation bore an analogy to the martensitic one in carbide precipitation

  11. Surfactant-thermal syntheses, structures, and magnetic properties of Mn-Ge-sulfides/selenides

    KAUST Repository

    Zhang, Guodong; Li, Peizhou; Ding, Junfeng; Liu, Yi; Xiong, Weiwei; Nie, Lina; Wu, Tao; Zhao, Yanli; Tok, Alfred Iing Yoong; Zhang, Qichun

    2014-01-01

    tetrahedra, MnGe2Se7 trimer, and MnGe3Se10 T2 cluster. Compounds 1-3 have been fully characterized by single-crystal X-ray diffraction (XRD), powder XRD, UV-vis spectra, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Moreover

  12. Electronic Phase Separation in Pr1x(Ca, Sr)xMnO3δ and Tunneling Magnetoresistance in Sr2FeMoO6

    International Nuclear Information System (INIS)

    Niebieskikwiat, Dario

    2003-01-01

    In this work, we approach two aspects of the physics of magnetic perovskites presenting colossal magnetoresistance (CMR). Firstly, we go deeply into the phase separation (PS) between the ferromagnetic (FM) metallic state and the antiferro-magnetic (AFM) charge ordered (CO) insulating state, in manganites of the type Pr 1x (Ca,Sr) x MnO 3δ . Secondly, and more briefly, we analyze the problem of the influence of the grain boundary insulating barriers on the tunneling magnetoresistance in the Sr 2 FeMoO 6 double perovskite.The use of different measurement techniques allowed us to make a complete characterization of the PS state in the compounds Pr 0 .65Ca 0.35-y Sr y MnO 3 for 0≤ y ≤ 0.20, Pr 0 .5Sr 0.5-z Ca z MnO 3 for z = 0, 0.1 and 0.2 and Pr 1 -x Ca x-0.3 Sr 0 .3MnO 3 (0.46≤ x ≤ 0.54), that were prepared in our laboratory.The structural studies of these materials were performed at room temperature by means of X-ray diffraction. At low temperatures, the phase coexistence was observed by global magnetic techniques, as SQUID magnetometry and neutron diffraction, as well as measurements sensitive to the local magnetic environment, as electron spin resonance (ESR).The electrical characterization, performed through resistivity and thermoelectric power (Seebeck effect) measurements, allowed us to elucidate the characteristics of the metal-insulator transitions, which are directly related to the magnetic properties of the PS state. In Pr 0 .65Ca 0.35-y Sr y MnO 3 compound we studied the effects of the average ionic radius of the A site of the perovskite ( A > ) keeping constant the carrier concentration (x = 0.35). This material presents an evolution from a CO insulating phase for small A > (y =0), towards the FM metallic phase for large A > (y = 0.20). In the intermediate region, where a first order metal-insulator transition occurs, the strong competition between both phases induces the PS state in a wide temperature range. In order to quantify this coexistence

  13. ¿Cómo construir una matriz de riesgo operativo?

    Directory of Open Access Journals (Sweden)

    Carlos Palma Rodríguez

    2011-01-01

    Full Text Available El artículo trata de explicar qué es el riesgo operativo en una empresa financiera o bancaria, cómo se identifica y se cuantifica, cómo se controla y las medidas utilizadas para mitigar o eliminarlo. El instrumento para conocer este tipo de riesgo, es la construcción de una matriz, que permite identificar el riesgo operativo, con los niveles de riesgo (viabilidad e impacto con la exposición asociada del riesgo operativo. Así mismo se pone un ejemplo de matriz operativo, así como sus resultados. Por último se proponen recomendaciones para la administración del riesgo en las empresas financieras o bancarias.

  14. Heat capacities and phase analysis of the superconductive compounds Mosub(6+y0) Se8 and Gdsub(x0) Mosub(6+y0) Se8

    International Nuclear Information System (INIS)

    Nerz, K.P.

    1979-02-01

    High precision heat capacity measurements were performed on a high quality sample of Mo 6 Se 8 . The values obtained for the Sommerfeld-constant γ, density of states N(Esub(F)) and entropy S 2 (Tsub(c)) of the electronic system are a factor 1.5 to 2 larger than have been published earlier by other groups. The differences are attributed to the lower concentration of impurity phases in our sample. Our sample of Mo 6 Se 8 shows a discontinuity in the electronic heat capacity at Tsub(c) with a relative height (Csub(es)-Csub(en))/Csub(en) which is a factor 1.6 larger compared to an ideal BCS-superconductor. The energy gap in the excitation spectrum of the superconductor Mo 6 Se 8 is a factor 1.4 wider than for an ideal BCS-superconductor in the observed temperature regime. Our data for the electronic heat capacity of the superconducting phase Mo 6 Se 8 are in good agreement with the calculated values corresponding to the 'strong coupling'-model of Padamsee et al. For the characteristic quantity of the electron-phonon interaction, lambda, a value of 0.8 was calculated. All these results support the conclusions that Mo 6 Se 8 behaves like a superconductor with a strong electron-phonon interaction. In addition heat capacity measurements have been made for samples of the ternary Chevrel-phase compounds 'Gdsub(x 0 )Mosub(6+y 0 )Se 8 ' which were prepared by a variety of methods. A quantitative analysis of impurity phases has been made from the heat capacity data. (orig.) [de

  15. Theoretical investigation of lithium adsorption, diffusion and coverage on MX2 (M = Mo, W; X = O, S, Se, Te) monolayers

    Science.gov (United States)

    Ersan, F.; Ozaydin, H. D.; Gökoğlu, G.; Aktürk, E.

    2017-12-01

    It is important to improve the high-efficient anode materials for Li batteries, which require the large capacity, high stability and mobility. In this work, we present the adsorption and diffusion properties of lithium atom on MX2 (M = Mo, W; X = O, S, Se, Te) transition metal dichalcogenide structures using first principles calculations within density functional theory. All the MX2 systems considered are semiconductor in bare state with band gaps between 0.93 eV (MoO2) and 1.79 eV (WS2). They turn into metal upon single Li adsorption. Li atom is adsorbed on MoO2 and WO2 rather stronger than other systems. The energy barrier for diffusion of single Li on MX2 varies between 0.15 eV and 0.28 eV which are lower or comparable to that of graphene or silicene. Two Li atoms are preferably adsorbed on MX2 monolayer symmetrically at opposite sides with high adsorption energy. The increasing number of Li atoms does not remarkably affect the adsorption energy per Li atom. This can be attributed to that Li atoms do not accumulate on certain regions of the surface. The systems under investigation provide insights into exploring electronic properties which are rather adequate for possible applications in Li-ion batteries.

  16. Lattice parameter values and phase transitions for the Cu2Cd1-zMnzSnSe4 and Cu2Cd1-zFezSnSe4 alloys

    International Nuclear Information System (INIS)

    Moreno, E.; Quintero, M.; Morocoima, M.; Quintero, E.; Grima, P.; Tovar, R.; Bocaranda, P.; Delgado, G.E.; Contreras, J.E.; Mora, A.E.; Briceno, J.M.; Avila Godoy, R.; Fernandez, J.L.; Henao, J.A.; Macias, M.A.

    2009-01-01

    X-ray powder diffraction measurements and differential thermal analysis (DTA) were made on polycrystalline samples of the Cu 2 Cd 1-z Mn z SnSe 4 and Cu 2 Cd 1-z Fe z SnSe 4 alloy systems. The diffraction patterns were used to show the equilibrium conditions and to derive lattice parameter values. For Cu 2 Cd 0.8 Fe 0.2 SnSe 4 as well as for Cu 2 Cd 0.2 Fe 0.8 SnSe 4 the crystal structures were refined using the Rietveld method. It was found that the internal distortion parameter σ decreases as Cd is replaced by either Mn and/or Fe. For the Cu 2 Cd 1-z Mn z SnSe 4 and Cu 2 Cd 1-z Fe z SnSe 4 alloy systems, only two single solid phase fields, the tetragonal stannite α(I4-bar2m) and the wurtz-stannite δ (Pmn2 1 ) structures were found to occur in the diagram. In addition to the tetragonal stannite α phase extra X-ray diffraction lines due to MnSe and/or FeSe 2 were observed for as grown samples in the range 0.7 < z < 1.0. However, it was found that the amount of the extra phase decreased for the compressed samples.

  17. El edificio Botines de León. Cómo se hizo

    Directory of Open Access Journals (Sweden)

    González Moreno-Navarro, José Luis

    2002-12-01

    Full Text Available The authors provide historic data on the construction process of the Bolines Building and offer their interpretation of the reasons for the "style" Gaudí used for the facades and the volume of the whole. However; the main part is given over lo describing the structure of the building which they consider surprising. They explain the construction procedures -some of them remarkable-used by the architect in the foundations, structure and roof, including safety margins, according lo the geotechnical report drawn up in 1993, which substantiates the criticism by Gaudi's contemporaries regarding the foundations. It also shows that although the slender walls have stood up lo a hundred years of gravitational force. there is no safety margin. It aII explains that his original system for collecting and channeling rainwater on the roof -correct in it's structural design and construction- was not entirely advantageous for the occupants. The authors also draw attention to the way in which the restorers kept in mind the overall concept of the building and the care they look in its rehabilitation, although they had no alternative but lo correct "young " Gaudi and rectify all his constructional slips.Los autores del articulo aportan algunos datos históricos acerca del proceso de construcción del monumento, ofrecen su interpretación sobre las razones de cómo Gaudí compuso las fachadas y el volumen del conjunto y, principalmente, describen el edificio -al cual califican de sorprendente- desde el punto de vista estructural.Se explican los procedimientos constructivos -algunos bien singulares- utilizados por el arquitecto en cimientos, estructura y cubierta, reflejando el margen de seguridad que ofrecían según el informe geotécnico realizado en 1993. Éste ratifica, por ejemplo. que las criticas que recibieron en su día las cimentaciones eran justificados; demuestra, también, que a pesar de que el comportamiento durante los cien años que han durado las

  18. Flux synthesis, modulated crystal structures, and physical properties of REMn0.5SeO (RE = La, Ce)

    International Nuclear Information System (INIS)

    Peschke, Simon; Johrendt, Dirk; Nitsche, Fabian

    2015-01-01

    The selenide oxides REMn 0.5 SeO (RE = La, Ce) were synthesized by heating RE 2 O 3 , RE, Mn, and Se in a NaI/KI flux at 800 C, and their modulated crystal structures determined by X-ray single crystal and powder diffraction {P 1 1 2/n(αβ1/2)0s, Z = 2, LaMn 0.5 SeO: a = 405.7(1), b = 405.7(1), c = 915.2(1) pm, γ = 90 , q = [1/10, -1/10, 1/2]; CeMn 0.5 SeO: a = 402.0(1), b = 401.8(1), c = 910.7(1) pm, γ = 90.000(4) , q = [0.0789(2), -0.0783(2), 1/2]}. The structures are related to the ZrCuSiAs-type structure with ordered vacancies at the manganese sites. The resulting modulations of the checkerboard pattern in the [Mn 0.5 Se] layers can be approximated by 10a x 10b x 2c and 51a x 51b x 2c supercells in LaMn 0.5 SeO and CeMn 0.5 SeO, respectively. Both compounds are insulators. The optical bandgap of LaMn 0.5 SeO was determined to 2.13 eV from the Kubelka-Munk function. Magnetic measurements indicate antiferromagnetic ordering of the Mn 2+ moments with Neel points well above room temperature, as known from related manganese compounds. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. The interplay between excitons and trions in a monolayer of MoSe2

    Science.gov (United States)

    Lundt, N.; Cherotchenko, E.; Iff, O.; Fan, X.; Shen, Y.; Bigenwald, P.; Kavokin, A. V.; Höfling, S.; Schneider, C.

    2018-01-01

    The luminescence and absorption properties of transition metal dichalcogenide monolayers are widely determined by neutral and charged excitonic complexes. Here, we focus on the impact of a free carrier reservoir on the optical properties of excitonic and trionic complexes in a MoSe2 monolayer at cryogenic temperatures. By applying photodoping via a non-resonant pump laser, the electron density can be controlled in our sample, which is directly reflected in the contribution of excitons and trions to the luminescence signal. We find significant shifts of both the exciton and trion energies in the presence of an induced electron gas both in power- and in time evolution (on the second to minute scale) in our photoluminescence spectra. In particular, in the presence of the photo-doped carrier reservoir, we observe that the splitting between excitons and trions can be enhanced by up to 4 meV. This behaviour is phenomenologically explained by an interplay between an increased screening of excitons via electrons in our system and a modification of the Fermi level. We introduce a simple but still quantitative treatment of these effects within a variational approach that takes into account both screening and phase space filling effects.

  20. Anisotropy of the optical absorption in layered single crystals of MoRe0.001Se1.999

    International Nuclear Information System (INIS)

    Vora, Mihir M.; Vora, Aditya M.

    2007-01-01

    Energy gap of MoRe 0.001 Se 1.999 single crystal has been determined by fundamental absorption methods. The incident light was polarized along c-axis of the crystals. The interpretion of the data is given within frameworks of two and three dimensional models. Both direct and indirect transitions are involved in the absorption process. The indirect transition was found to be allowed with two phonons participating in the process. The three dimensional model could be used to describe the optical properties of the single crystal. The energy gaps depend upon the amount of the intercalating Re material, which show the anisotropy of the chemical bonds. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Fe-Mn bi-metallic oxides loaded on granular activated carbon to enhance dye removal by catalytic ozonation.

    Science.gov (United States)

    Tang, Shoufeng; Yuan, Deling; Zhang, Qi; Liu, Yameng; Zhang, Qi; Liu, Zhengquan; Huang, Haiming

    2016-09-01

    A Fe-Mn bi-metallic oxide supported on granular activated carbon (Fe-Mn GAC) has been fabricated by an impregnation-desiccation method and tested in the catalytic ozonation of methyl orange (MO) degradation and mineralization. X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy characterizations revealed that Fe-Mn oxides were successfully loaded and uniformly distributed on the GAC, and nitrogen adsorption isotherms showed that the supported GAC retained a large surface area and a high pore volume compared with the pristine GAC. The catalytic activity was systematically assessed by monitoring the MO removal efficiencies at different operational parameters, such as catalyst dosage, initial solution pH, and ozone flow rate. The Fe-Mn GAC exhibited better catalytic activity relative to ozone alone and GAC alone, improving the TOC removal by 24.5 and 11.5 % and COD removal by 13.6 and 7.3 %, respectively. The reusability of the hybrid was examined over five consecutive cyclic treatments. The Fe-Mn GAC catalytic activity was only a slight loss in the cycles, showing good stability. The addition of Na2CO3 as hydroxyl radicals (•OH) scavengers proved that the catalytic ozonation mechanism was the enhanced generation of •OH by the Fe-Mn GAC. The above results render the Fe-Mn GAC an industrially promising candidate for catalytic ozonation of dye contaminant removal.

  2. Spin-dependent and photon-assisted transmission enhancement and suppression in a magnetic-field tunable ZnSe/Zn{sub 1–x}Mn{sub x}Se heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chun-Lei, E-mail: licl@cnu.edu.cn [Laboratory for Micro-sized Functional Materials, College of Elementary Education, Capital Normal University, Beijing 100048 (China); Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Yuan, Rui-Yang [Center for Theoretical Physics, Department of Physics, Capital Normal University, Beijing 100048 (China); Guo, Yong, E-mail: guoy66@tsinghua.edu.cn [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)

    2016-01-07

    Using the effective-mass approximation and Floquet theory, we theoretically investigate the terahertz photon-assisted transport through a ZnSe/Zn{sub 1−x}Mn{sub x}Se heterostructure under an external magnetic field, an electric field, and a spatially homogeneous oscillatory field. The results show that both amplitude and frequency of the oscillatory field can accurately manipulate the magnitude of the spin-dependent transmission probability and the positions of the Fano-type resonance due to photon absorption and emission processes. Transmission resonances can be enhanced to optimal resonances or drastically suppressed for spin-down electrons tunneling through the heterostructure and for spin-up ones tunneling through the same structure, resonances can also be enhanced or suppressed, but the intensity is less than the spin-down ones. Furthermore, it is important to note that transmission suppression can be clearly seen from both the spin-down component and the spin-up component of the current density at low magnetic field; at the larger magnetic field, however, the spin-down component is suppressed, and the spin-up component is enhanced. These interesting properties may provide an alternative method to develop multi-parameter modulation electron-polarized devices.

  3. MO ELABORAR ENCUESTAS PARA MEDIR EL USO DE LA INFORMÁTICA

    OpenAIRE

    Elsa del Carmen Gutiérrez Báez

    2010-01-01

    Cuando hablamos de instrumentos para medir la efectividad del uso de la Informática, nos detenemos en las encuestas como un instrumento poco utilizado en el proceso de aprendizaje. En este material se propone su uso como instrumento fundamental de investigación. Se define, qué es una encuesta, cuántos tipos existen, se muestra cómo se pueden redactar las diferentes preguntas y cómo se tabulan; a partir de ejemplos prácticos aplicados en la Educación Infantil.

  4. sp-d Exchange Interactions in Wave Function Engineered Colloidal CdSe/Mn:CdS Hetero-Nanoplatelets.

    Science.gov (United States)

    Muckel, Franziska; Delikanli, Savas; Hernández-Martínez, Pedro Ludwig; Priesner, Tamara; Lorenz, Severin; Ackermann, Julia; Sharma, Manoj; Demir, Hilmi Volkan; Bacher, Gerd

    2018-03-14

    In two-dimensional (2D) colloidal semiconductor nanoplatelets, which are atomically flat nanocrystals, the precise control of thickness and composition on the atomic scale allows for the synthesis of heterostructures with well-defined electron and hole wave function distributions. Introducing transition metal dopants with a monolayer precision enables tailored magnetic exchange interactions between dopants and band states. Here, we use the absorption based technique of magnetic circular dichroism (MCD) to directly prove the exchange coupling of magnetic dopants with the band charge carriers in hetero-nanoplatelets with CdSe core and manganese-doped CdS shell (CdSe/Mn:CdS). We show that the strength of both the electron as well as the hole exchange interactions with the dopants can be tuned by varying the nanoplatelets architecture with monolayer accuracy. As MCD is highly sensitive for excitonic resonances, excited level spectroscopy allows us to resolve and identify, in combination with wave function calculations, several excited state transitions including spin-orbit split-off excitonic contributions. Thus, our study not only demonstrates the possibility to expand the extraordinary physical properties of colloidal nanoplatelets toward magneto-optical functionality by transition metal doping but also provides an insight into the excited state electronic structure in this novel two-dimensional material.

  5. A study on molybdenum sulphoselenide (MoSxSe2−x, 0 ≤ x ≤ 2) thin films: Growth from solution and its properties

    International Nuclear Information System (INIS)

    Anand, T. Joseph Sahaya; Shariza, S.

    2012-01-01

    Highlights: ► Effect of deposition time on the properties of molybdenum chalcogenide thin films. ► First time to compare the study of binary and ternary molybdenum chalcogenides. ► No previous report on ternary molybdenum sulphoselenide by electrodeposition. ► Semiconducting parameters by CV analysis promising to be good solar cell material. - Abstract: Thin films of molybdenum sulphoselenide, MoS x Se 2−x , (0 ≤ x ≤ 2) have been electrosynthesized on indium-tin-oxide (ITO)-coated glass and stainless steel substrates. The films were characterized for their structural, morphological and compositional characteristics. Their optical and semiconducting parameters were also analysed in order to determine the suitability of the thin films for photoelectrochemical (PEC)/solar cell applications. Structural analysis via X-ray diffraction (XRD) analysis reveals that the films are polycrystalline in nature. Scanning electron microscope (SEM) studies reveals the films were adherent to the substrate with uniform in nature which also confirmed by Transmission electron microscope (TEM). Compositional analysis via energy dispersive X-ray (EDX) technique confirms the presence of Mo, S and Se elements in the films. The optical studies show that the films are of direct bandgap. Results on the semiconductor parameters analysis of the films showed that the nature of the Mott–Schottky plots indicates that the films obtained are of n-type material. For all films, the semiconductor parameter values come in the better range of other transition metal chalcogenides which has proven that MoSSe thin films are capable as solar/PEC cell materials.

  6. Sign system choice influence on the substance formation forecast in A2MoO4-B2(MoO4)3 and A2MoO4-CMoO4 systems

    International Nuclear Information System (INIS)

    Manzanov, Yu.E.; Lutsik, V.I.; Mokhosoev, M.V.

    1987-01-01

    Three sign spaces were used for forecasting compound formation in A 2 MoO 4 -B 2 (MoO 4 ) 3 (5:1 ratio, where A-Li, Na, K, Rb, Cs; B-Al, In, Ga, Sc, Cr, Fe, Bi, La, Nd, Sm-Lu, Y) and A 2 MoO 4 -CMoO 4 (1:2 ratio, where A-Li, Na, K, RB, Cs, Tl; C-Mg, Ca, Sr, Ba, Cu, Zn, Cd, Pd, Mn, Co, Ni) systems: 1-electron distribution on energy shells of cations and their valency; 2-the type of incomplete electron shell, charge of cations, three first ionization potentials, standard heat capacity, ionic radius of cations; 3-standard formation enthalpy and standard entropy, oxide melting points and ionic radius of cations. It is shown that sign space, related with thermodynamic properties of oxides contains data, necessary for forecasting interaction in molybdate systems. This enables to improve reliability of forecasting

  7. Controlling magnetism of MoS2 sheets by embedding transition-metal atoms and applying strain.

    Science.gov (United States)

    Zhou, Yungang; Su, Qiulei; Wang, Zhiguo; Deng, Huiqiu; Zu, Xiaotao

    2013-11-14

    Prompted by recent experimental achievement of transition metal (TM) atoms substituted in MoS2 nanostructures during growth or saturating existing vacancies (Sun et al., ACS Nano, 2013, 7, 3506; Deepak et al., J. Am. Chem. Soc., 2007, 129, 12549), we explored, via density functional theory, the magnetic properties of a series of 3d TM atoms substituted in a MoS2 sheet, and found that Mn, Fe, Co, Ni, Cu and Zn substitutions can induce magnetism in the MoS2 sheet. The localizing unpaired 3d electrons of TM atoms respond to the introduction of a magnetic moment. Depending on the species of TM atoms, the substituted MoS2 sheet can be a metal, semiconductor or half-metal. Remarkably, the applied elastic strain can be used to control the strength of the spin-splitting of TM-3d orbitals, leading to an effective manipulation of the magnetism of the TM-substituted MoS2 sheet. We found that the magnetic moment of the Mn- and Fe-substituted MoS2 sheets can monotonously increase with the increase of tensile strain, while the magnetic moment of Co-, Ni-, Cu- and Zn-substituted MoS2 sheets initially increases and then decreases with the increase of tensile strain. An instructive mechanism was proposed to qualitatively explain the variation of magnetism with elastic strain. The finding of the magnetoelastic effect here is technologically important for the fabrication of strain-driven spin devices on MoS2 nanostructures, which allows us to go beyond the current scope limited to the spin devices within graphene and BN-based nanostructures.

  8. MO ELABORAR ENCUESTAS PARA MEDIR EL USO DE LA INFORMÁTICA

    Directory of Open Access Journals (Sweden)

    Elsa del Carmen Gutiérrez Báez

    2010-07-01

    Full Text Available Cuando hablamos de instrumentos para medir la efectividad del uso de la Informática, nos detenemos en las encuestas como un instrumento poco utilizado en el proceso de aprendizaje. En este material se propone su uso como instrumento fundamental de investigación. Se define, qué es una encuesta, cuántos tipos existen, se muestra cómo se pueden redactar las diferentes preguntas y cómo se tabulan; a partir de ejemplos prácticos aplicados en la Educación Infantil.

  9. Spin reversal in Gd(Me,MnO3 (Me = Co, Ni

    Directory of Open Access Journals (Sweden)

    Gutiérrez, D.

    2004-06-01

    Full Text Available Partial substitution of the rare-earth by calcium at the cationic site of the ABO3 perovskites may show extraordinary effects of spin reversal due to a negative polarization between the rare-earth and the manganese networks, as it occurs in the solid solution Gd1‑xCaxMnO3. We present herein similar effects in gadolinium perovskites of the Gd(Me,MnO3 type, in which the manganese sublattice has been partially substituted by transition metal elements Me, leaving the gadolinium network intact. The spin reversal phenomena is observed at a critical concentration of x(Me = 1/3, which implies an optimum number of pairs Mn3+-Mn4+. Néel temperatures of 48 and 67 K are obtained for Me = Co and Ni, respectively, at the optimum concentration of substituent. A comparison between these different solid solutions allows us to generalize the interpretation of two interacting magnetic sublattices : a Mn-based ferromagnetic one and a negatively-aligned gadolinium network.La sustitución parcial del lantánido por el elemento calcio en el sitio catiónico (sitio A de la perovskita ABO3 puede dar lugar a efectos importantes ligados a una inversión del espín. Dicha inversión se debe a una interacción negativa entre la tierra rara y la subred de manganeso, tal como ocurre en la solución solida Gd1-xCaxMnO3. Se presentan en este trabajo efectos similares que ocurren en las perovskitas de gadolinio de fórmula Gd(Me,MnO3, en las cuales la subred de manganeso (sitio B ha sido reemplazada parcialmente por otros metales de transición Me, dejando intacta la subred de gadolinio. Se observa el fenómeno de inversión de espín para una concentración crítica x(Me = 1/3, para la cual se logra una cantidad óptima de pares Mn3+‑Mn4+. Para esta concentración crítica se observan temperaturas de Néel antiferromagnéticas del orden de 48 y 67 K, respectivamente para Me = Co y Ni. Un análisis comparativo entre estos diferentes sistemas permite generalizar la

  10. Topological insulator homojunctions including magnetic layers: the example of n-p type (n-QLs Bi.sub.2./sub.Se.sub.3./sub./Mn-Bi.sub.2./sub.Se.sub.3./sub.) heterostructures

    Czech Academy of Sciences Publication Activity Database

    Vališka, M.; Warmuth, J.; Michiardi, M.; Vondráček, Martin; Ngankeu, A.S.; Holý, V.; Sechovský, V.; Springholz, G.; Bianchi, M.; Wiebe, J.; Hofmann, P.; Honolka, Jan

    2016-01-01

    Roč. 108, č. 26 (2016), 1-4, č. článku 262402. ISSN 0003-6951 R&D Projects: GA MŠk(CZ) LM2011029; GA MŠk LO1409; GA ČR(CZ) GA14-30062S Grant - others:AV ČR(CZ) Fellowship J. E. Purkyně Institutional support: RVO:68378271 Keywords : topological insulator * Mn-Bi2Se 3 * homojunction * ARPES Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.411, year: 2016

  11. Microwave-assisted aqueous synthesis of transition metal ions doped ZnSe/ZnS core/shell quantum dots with tunable white-light emission

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jie [Laboratory of Advanced Materials, Fudan University, Shanghai 200438 (China); Chen, Qiuhang; Zhang, Wanlu; Mei, Shiliang; He, Liangjie; Zhu, Jiatao [Engineering Research Center of Advanced Lighting Technology, Ministry of Education, Institute for Electric Light Sources, Fudan University, Shanghai 200433 (China); Chen, Guoping [School of Information Science and Technology, Fudan University, Shanghai 200433 (China); Guo, Ruiqian, E-mail: rqguo@fudan.edu.cn [Engineering Research Center of Advanced Lighting Technology, Ministry of Education, Institute for Electric Light Sources, Fudan University, Shanghai 200433 (China)

    2015-10-01

    Highlights: • ZnSe-based QDs were formed via a microwave-assisted aqueous approach. • The stabilizer, ZnS coats and UV irradiation played a role in the PL enhancement. • Tunable white-light-emitting Mn:ZnSe QDs and Cu,Mn:ZnSe/ZnS QDs were synthesized. • The formation mechanism of Cu,Mn:ZnSe QDs was clarified. • The corresponding CIE color coordinates of different PL spectra were obtained. - Abstract: Synthesis of bright white-light emitting Mn and Cu co-doped ZnSe/ZnS core/shell quantum dots (QDs) (Cu,Mn:ZnSe/ZnS) was reported. Water-soluble ZnSe-based QDs with Mn and Cu doping were prepared using a versatile hot-injection method in aqueous solution with a microwave-assisted approach. Influence of the Se/S ratio, stabilizer, refluxing time and the concentration of Cu/Mn dopant ions on the particle size and photoluminescence (PL) were investigated. The as-prepared QDs in the different stages of growth were characterized by X-ray powder diffractometer (XRD), high-resolution transmission electron microscopy (HRTEM), UV–visible (UV–vis) spectrophotometer, and fluorescence spectrophotometer. It is found that these ZnSe-based QDs synthesized under mild conditions exhibit emission in the range of 390–585 nm. The PL quantum yield (QY) of the as-prepared water-soluble ZnSe QDs can be up to 24.3% after the UV-irradiation treatment. The band-gap emission of ZnSe is effectively restrained through Mn and Cu doping. The refluxing time influences the doping of not only Mn, but also Cu, which leads to the best refluxing time of Mn:ZnSe and the red-shift of the emission of Cu:ZnSe d-dots. Co-doping induced white-light emission (WLE) from Cu,Mn:ZnSe/ZnS core/shell QDs were obtained, which can offer the opportunity for future-generation white-light emitting diodes (LEDs)

  12. Obtainment of Hg-free Mn/Zn solutions from spent alkaline batteries; Obtencion de soluciones de Mn/Zn libres de Hg provenientes de pilas alcalinas gastadas

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Nicolas, L.; Espinosa-Ramirez, I. [Instituto Politecnico Nacional, UPALM, Mexico, D.F. (Mexico)]. E-mail: lepeni@hotmail.com; Aguilar, M. [Instituto de Fisica, UNAM, Mexico, D.F. (Mexico); Palacios-Beas, E. [Instituto Politecnico Nacional, UPALM, Mexico, D.F. (Mexico)

    2009-09-15

    As in many other countries, the excessive consumption of alkaline batteries in Mexico has generated highly contaminating wastes, with heavy metal contents such as Mn, Zn, Fe, Hg, Cu and Ni, among others. This has caused a large degree of environmental degradation with repercussions for the health of living beings. Because there are no regulations regarding the disposal of spent batteries, they are thrown out with the rest of the domestic wastes or directly into nature, ending up in open-air landfills or containers where they are incinerated, thereby contaminating the planet's environment, soil and springs. The present work studies the obtainment of solutions of Hg-free Mn and Zn (Mn/Zn {>=} 1) from spent alkaline batteries for use in synthesis of (Mn,Zn)Fe{sub 2}O{sub 4} ferrite by a wet method. The effect is analyzed of the dissolution medium (H{sub 2}SO{sub 4}/H{sub 2}O{sub 2}, HCl and HCl/NO{sub 3}) temperature and time on the percentage of dissolution of the metals present in the electrode material, characterized by atomic absorption (AA) spectroscopy and x-ray diffraction (XRD). The results of the investigation indicate that the best dissolution conditions are MD=H{sub 2}SO{sub 4}/H{sub 2}O{sub 2}, T=50 degrees Celsius and t =30 min, where 94.1 and 90.7 % (w/w) of Mn and Zn are obtained, respectively, with Mn/Zn = 1.51. The mercury content was determined to be 3.91%, higher than that stated by the battery specifications, which is recovered by dissolving with HCl/HNO{sub 3} in the residual solid. [Spanish] En Mexico como en muchos otros paises, el consumo excesivo de pilas alcalinas ha generado desechos altamente contaminantes, con contenidos de metales pesados como Mn, Zn, Fe, Hg, Cu y Ni entre otros, que han provocado un gran deterioro en el medio ambiente repercutiendo en la salud de los seres vivos. Dado que no se tiene una regulacion en cuanto a la disposicion de pilas gastadas, estas se desechan con el resto de las residuos domesticos o directamente

  13. Synthesis of double molybdates of copper (1) and trivalent metals, CuR(MoO4)2

    International Nuclear Information System (INIS)

    Klevtsov, P.V.; Perepelitsa, A.P.; Sinkevich, A.V.; Ishchenko, V.N.; Fomenko, V.V.; Nagornyj, P.G.; AN SSSR, Novosibirsk. Inst. Neorganicheskoj Khimii)

    1987-01-01

    The method of Cu 2 O solid-phase synthesis was applied to prepare CuR(MoO 4 ) 2 in the vacuum at 480-500 deg C. Cu 2 O, R 2 O 3 and MoO 3 or R 2 '(MoO 4 ) 2 (R'=Ce, Pr, Tb) and MoO 3 were the initial components. The methods of X-ray phase analysis and IR spectroscopy were applied to discover 5 types of compound structures. Among them only CuIn(MoO 4 ) 2 is found crystallized in the known structural type LiFe(WO 4 ) 2 (modification of tungstite structure, (Fe,Mn)WO 4 ). Thermal behaviour of double molybdates is studied thermographically

  14. Neutron diffraction study of single crystalline ErCo10Mo2

    International Nuclear Information System (INIS)

    Janssen, Y.; De Boer, F.R.; Brueck, E.; Tegus, O.; Ma, L.; Buschow, K.H.J.; Reehuis, M.

    1999-01-01

    Complete text of publication follows. The ferrimagnetic intermetallic compound ErCo 10 Mo 2 (Tc = 600 K) crystallizes in the tetragonal ThMn 12 -type structure (space group 14/mmm). The Co and Mo atoms may share three crystallographic sites (8f, 8i and 8j). Earlier neutron powder diffraction experiments show that Mo has a strong preference for the 8i-site and that the magnetic ordering at low temperature is planar. Furthermore ErCo 10 Mo 2 has been reported to show one [2] or more [3] spin-reorientation transitions from planar to axial magnetic ordering. Recently we succeeded in growing a single-crystalline sample of ErCo 10 Mo 2 . Magnetic measurements in 1T show one spin-reorientation transition at about 135 K. Neutron diffraction experiments were performed to investigate a possible link between the magnetic properties and the site occupation by Mo. Our results show that our sample has the Mo atoms exclusively occupying half the 8i-sites. There is no evidence for a crystallographic superstructure. Furthermore, below 150 K some reflections strongly increase due to the growing Er magnetic moment. (author)

  15. Abnormal Grain Growth in the Heat Affected Zone of Friction Stir Welded Joint of 32Mn-7Cr-1Mo-0.3N Steel during Post-Weld Heat Treatment

    Directory of Open Access Journals (Sweden)

    Yijun Li

    2018-04-01

    Full Text Available The abnormal grain growth in the heat affected zone of the friction stir welded joint of 32Mn-7Cr-1Mo-0.3N steel after post-weld heat treatment was confirmed by physical simulation experiments. The microstructural stability of the heat affected zone can be weakened by the welding thermal cycle. It was speculated to be due to the variation of the non-equilibrium segregation state of solute atoms at the grain boundaries. In addition, the pressure stress in the welding process can promote abnormal grain growth in the post-weld heat treatment.

  16. Room-temperature synthesis of MnMoO{sub 4}{center_dot}H{sub 2}O nanorods by the microemulsion-based method and its photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Mi Yan; Huang Zaiyin; Zhou Zeguang; Hu Feilong; Meng Qiufeng [College of Chemistry and Ecological Engineering, Guangxi University for Nationalities, Nanning 530006 (China)], E-mail: hzy210@yahoo.cn

    2009-09-01

    Manganese molybdate hydrates (MnMoO{sub 4}{center_dot}H{sub 2}O) nanorods have been synthesized at room temperature by a facile water-in-oil reverse microemulsion method. This technique was carried out in the reverse microemulsion of OP-10 (Polyoxyethylene octylphenol ether)-n-octanol-water-cyclohexane with a water/surfactant molar ratio {omega} = 10. Field-emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that the diameters of these formed nanorods about 70 nm and lengthe up to 4 {mu}m, respectively. High-resolution transmission electron microscopy (HRTEM) results showed that each nanorod was formed by serveral nanobelts which are stacked by a layer-by-layer process. These unique nanorods demonstrate good photocatalytic properties.

  17. Aqueous-phase synthesis and color-tuning of core/shell/shell inorganic nanocrystals consisting of ZnSe, (Cu, Mn)-doped ZnS, and ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jongwan; Yoon, Sujin [Department of Chemistry and Research Institute for Natural Science, Hanyang University, Seoul, 133-791 (Korea, Republic of); Kim, Felix Sunjoo, E-mail: fskim@cau.ac.kr [School of Chemical Engineering and Materials Science, Chung-Ang University, Seoul, 156-756 (Korea, Republic of); Kim, Nakjoong, E-mail: kimnj@hanyang.ac.kr [Department of Chemistry and Research Institute for Natural Science, Hanyang University, Seoul, 133-791 (Korea, Republic of)

    2016-06-25

    We report synthesis of colloidal nanocrystals based on ZnSe core, (Cu,Mn)-doped ZnS inner-shell, and ZnS outer-shell by using an eco-friendly method and their optical properties. Synthesis of core/shell/shell nanocrystals was performed by using a one-pot/three-step colloidal method with 3-mercaptopropionic acid as a stabilizer in aqueous phase at low temperature. A double-shell structure was employed with inner-shell as a host for doping and outer-shell as a passivation layer for covering surface defects. Copper and manganese were introduced as single- or co-dopants during inner-shell formation, providing an effective means to control the emission color of the nanocrystals. The synthesized nanocrystals showed fluorescent emission ranging from blue to green, to white, and to orange, adjusted by doping components, amounts, and ratios. The photoluminescence quantum yields of the core/doped-shell/shell nanocrystals approached 36%. - Highlights: • ZnSe/ZnS:(Cu,Ms)/ZnS core/(doped)shell/shell nanocrystals were synthesized in an aqueous phase. • Emission color of nanocrystals was controlled from blue to white to orange by adjusting the atomic ratio of Cu and Mn co-dopants. • Photoluminescence quantum yields of the colloidal nanocrystals approached 36%.

  18. Magnetic MoS2 pizzas and sandwiches with Mnn (n = 1-4) cluster toppings and fillings: A first-principles investigation

    Science.gov (United States)

    Zhang, Meng; Huang, Zhongjia; Wang, Xiao; Zhang, Hongyu; Li, Taohai; Wu, Zhaolong; Luo, Youhua; Cao, Wei

    2016-01-01

    The inorganic layered crystal (ILC) MoS2 in low dimensions is considered as one of the most promising and efficient semiconductors. To enable the magnetism and keep intrinsic crystal structures, we carried out a first-principles study of the magnetic and semiconductive monolayer MoS2 adsorbed with the Mnn (n = 1-4) clusters, and bilayer MoS2 intercalated with the same clusters. Geometric optimizations of the Mnn@MoS2 systems show the complexes prefer to have Mnn@MoS2(M) pizza and Mnn@MoS2(B) sandwich forms in the mono- and bi-layered cases, respectively. Introductions of the clusters will enhance complex stabilities, while bonds and charge transfers are found between external Mn clusters and the S atoms in the hosts. The pizzas have medium magnetic moments of 3, 6, 9, 4 μB and sandwiches of 3, 2, 3, 2 μB following the manganese numbers. The pizzas and sandwiches are semiconductors, but with narrower bandgaps compared to their corresponding pristine hosts. Direct bandgaps were found in the Mnn@MoS2(M) (n = 1,4) pizzas, and excitingly in the Mn1@MoS2(B) sandwich. Combining functional clusters to the layered hosts, the present work shows a novel material manipulation strategy to boost semiconductive ILCs applications in magnetics.

  19. Electrochemical performance of co-doped Li1.2Mn0.6Ni0.2O2 cathode materials

    CSIR Research Space (South Africa)

    David, K

    2013-04-01

    Full Text Available The composite material has a xLi2MnO3·(1-x)LiMO2 (M = Mn, Co, Ni) structure has been considered as one of the most promising cathode materials for advanced lithium-ion batteries due to their low-cost and high capacity (> 200 mAh g−1) between 4.8 V...

  20. Organic molecules passivated Mn doped Zinc Selenide quantum dots and its properties

    International Nuclear Information System (INIS)

    Archana, J.; Navaneethan, M.; Ponnusamy, S.; Hayakawa, Y.; Muthamizhchelvan, C.

    2011-01-01

    Quantum dots of Mn doped Zinc Selenide with N-Methylaniline as the capping agent was prepared by simple and inexpensive wet chemical method. Size of the particles observed by TEM was of the order of 2-4 nm which was well consistent with the size measured by UV analysis. The presence of paramagnetic substance Mn 2+ in the ZnSe quantum dots was confirmed by EPR measurement. Mn doped ZnSe nanoparticles exhibited a strong blue emission that was strongly dependent upon the Mn dopant level and the surface passivation produced by N-Methylaniline. The stability of the product was studied by thermal analysis which shows that this product is highly suitable for opto-electronic applications.

  1. Investigation on Aging σ-Phase Precipitation Kinetics and Pitting Corrosion of 22 Pct Cr Economical Duplex Stainless Steel with Mn Addition

    Science.gov (United States)

    Yang, Yinhui; Qian, Hao

    2018-05-01

    The influence of Mn addition on σ-phase precipitation kinetics and pitting corrosion of Fe-22Cr-1.9Ni-2.3Mo-0.2N-xMn low nickel type duplex stainless steel was investigated by medium- and high-temperature aging treatments of 600 °C and 800 °C. The microstructure analysis showed that the fine rod-shaped and coarsening dendritelike σ-phase precipitates formed at 600 °C and 800 °C, respectively, and the precipitate growth with the higher temperature was accelerated due to the partition of Mn, but Mn is not a strong σ-phase forming element like Cr, Mo during aging treatment at these two temperatures. At an early aging time of 800 °C, more precipitated nuclei with more Mn addition promote refinement of σ precipitates in later aging time. The kinetic behavior at 600 °C and 800 °C is related to diffusion-controlled growth of σ phase, and the σ-phase nucleation and growth are enhanced with more Mn addition and higher aging temperature due to a faster Mn diffusion rate. The difference in precipitation morphology for two aging temperatures was attributed to the different nucleation modes caused by kinetics parameter n variation. Increasing the aging temperature from 600 °C to 800 °C increased the susceptibility to pitting with higher Mn addition due to faster σ-phase precipitation kinetics.

  2. Graphite-(Mo,W)S2 intergrowth as a palaeoenvironmental proxy in metasedimentary rocks

    Science.gov (United States)

    Cabral, Alexandre Raphael; Zeh, Armin; da Silva Viana, Nívea Cristina; Schirmer, Thomas; Lehmann, Bernd

    2017-12-01

    Molybdenum enrichment in pristine organic-C-rich sedimentary rocks forms the basis for inferring the presence of dissolved oxygen in seawater. Organic matter removes dissolved hexavalent Mo from seawater where anoxic and euxinic conditions are attained. However, it is unknown whether this Mo-based proxy is retained under metamorphic conditions where organic C is no longer preserved. Here, we describe aggregates of graphite and molybdenite (MoS2) containing up to 21 mass per cent of W as tungstenite (WS2) in solid solution. These aggregates are disseminated in a sulfide-rich Mn-silicate-carbonate rock (queluzite), metamorphosed under amphibolite-facies conditions within the Archaean Barbacena greenstone belt in Minas Gerais, Brazil. Our finding indicates that: (i) W is, like Mo, a palaeoenvironmental proxy; (ii) the W proxy is sensitive to high fS2/fO2 environments; (iii) both Mo and W proxies survive amphibolite-facies overprint as (Mo,W)S2 intergrown with graphite. Archaean greenstones are potential candidates for storing palaeoenvironmental information as (Mo,W)S2-graphite intergrowths.

  3. Hyperfine interactions in MnAs studied by perturbed angular correlations of $\\gamma$-rays using the probe $^{77}$Br $\\rightarrow ^{77}$Se and first principles calculations for MnAs and other Mn pnictides

    CERN Document Server

    Gonçalves, J N; Correia, J G; Lopes, A M L

    2011-01-01

    The MnAs compound shows a first-order transition at T$_{c}$≈ 42$^{\\circ}$C, and a second-order transition at T$_{t}$ ≈120$^{\\circ}$C. The first-order transition, with structural (hexagonal-orthorhombic), magnetic (FM-PM) and electrical conductivity changes, is associated to magnetocaloric, magnetoelastic, and magnetoresistance effects. We report a study in a large temperature range from −196$^{\\circ}$C up to 140$^{\\circ}$C, using the $\\gamma\\!-\\!\\gamma$ perturbed angular correlations method with the radioactive probe $^{77}$Br→$^{77}$Se, produced at the ISOLDE-CERN facility. The electric field gradients and magnetic hyperfine fields are determined across the first- and second-order phase transitions encompassing the pure and mixed phase regimes in cooling and heating cycles. The temperature irreversibility of the 1st order phase transition is seen locally, at the nanoscopic scale sensitivity of the hyperfine field, by its hysteresis, detailing and complementing information obtained with macroscopic me...

  4. Adolescentes que utilizan servicios de atención primaria: ¿Cómo viven? ¿Por qué buscan ayuda y cómo se expresan?

    Directory of Open Access Journals (Sweden)

    Lílian dos Santos Palazzo

    Full Text Available El objetivo del estudio fue caracterizar a los adolescentes que utilizan los servicios de atención primaria de una comunidad; saber cómo se expresan en la búsqueda de ayuda médica, la atención recibida y aspectos sociofamiliares. De entre un total de 35 unidades de atención primaria urbanas pertenecientes a la red de salud pública del municipio de Pelotas (Brasil, 10 fueron elegidas al azar y entrevistados todos los individuos entre 13 y 19 años que consultaron al médico y no al psiquiatra durante tres meses. (n = 463. La utilización de los servicios tiene un carácter más bien curativo que preventivo. Los varones acuden menos y lo hacen principalmente con quejas somáticas, mientras que las jóvenes suelen manifestar quejas sexuales. Raros son los que expresan sus aflicciones emocionales, aunque algunos relatan problemas familiares, escolares y situaciones estresantes.

  5. Phase formation in K2O(K2CO3)-CdO-MoO3 system

    International Nuclear Information System (INIS)

    Tsirenova, G.D.; Tsybikova, B.A.; Bazarova, Zh.G.; Solodovnikov, S.F.; Zolotova, E.S.

    2000-01-01

    Phase formation in K 2 O(K 2 CO 3 )-CdO-MoO 3 system are studied by the methods of x-ray diffraction, thermal and crystal optical analyses. Three potassium-cadmium molybdates are detected: K 4 Cd(MoO 4 ) 3 with a new structure, alluodite-like K 4-2x Cd 1+x (MoO 4 ) 3 (0.26≤x≤0.38 at 470 Deg C) and K 4 CdMo 4 O 15 of K 4 MnMo 4 O 15 type. First of them decomposes in solid phase at 580 Deg C, and others melt incongruently at 720 and 515 Deg C correspondingly. It is established that K 4-2x Cd 1+x (MoO 4 ) 3 compound undergoes phase transition of the second type in the temperature interval of 500-550 Deg C. Phase diagram of quasibinary cross section K 2 MoO 4 -CdMoO 4 is plotted [ru

  6. Tuning Li2MO3 phase abundance and suppressing migration of transition metal ions to improve the overall performance of Li- and Mn-rich layered oxide cathode

    Science.gov (United States)

    Zhang, Shiming; Tang, Tian; Ma, Zhihua; Gu, Haitao; Du, Wubing; Gao, Mingxia; Liu, Yongfeng; Jian, Dechao; Pan, Hongge

    2018-03-01

    The poor cycling stability of Li- and Mn-rich layered oxide cathodes used in lithium-ion batteries (LIBs) has severely limited their practical application. Unfortunately, current strategies to improve their lifecycle sacrifice initial capacity. In this paper, we firstly report the synergistic improvement of the electrochemical performance of a Li1.2Ni0.13Co0.13Mn0.54O2 (LNCMO) cathode material, including gains for capacity, cycling stability, and rate capability, by the partial substitution of Li+ ions by Mg2+ ions. Electrochemical performance is evaluated by a galvanostatic charge and discharge test and electrochemical impedance spectroscopy (EIS). Structure and morphology are characterized by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Compared with the substitution of transition metal (TM) ions with Mg2+ ions reported previously, the substitution of Li+ ions by Mg2+ ions not only drastically ameliorates the capacity retention and rate performance challenges of LNCMO cathodes but also markedly suppresses their voltage fading, due to the inhibition of the migration of TM ions during cycling, while also increasing the capacity of the cathode due to an increased abundance of the Li2MO3 phase.

  7. ¿Cómo se leen los números?

    OpenAIRE

    Pedro Macizo; Amparo Herrera

    2012-01-01

    En los modelos de procesamiento numérico se asume que para llegar a la información fonológica que nos permite nombrar un dígito arábigo como “3”, tenemos que acceder previamente a su significado (la cantidad 3). Esto no es necesario cuando leemos una palabra numérica como “tres”, pues podemos pronunciarla sin entender a qué cantidad se refiere. Pero nuestro equipo ha mostrado recientemente que tanto la denominación de dígitos arábigos como la lectura de palabras numéricas pueden realizarse si...

  8. Binary and tertiary reaction cross-sections of V, Cr, Mn, Fe, Ni, Cu, Zr, Nb, Mo, Ta, W, Pt and their isotopes

    International Nuclear Information System (INIS)

    Garg, S.B.

    1982-01-01

    Neutron induced binary and tertiary reaction cross-sections have been evaluated for V, Cr, Mn, Fe, Ni, Cu, Zr, Nb, Mo, Ta, W, Pt and their isotopes in the 'energy range 0.5 MeV to 20 MeV using the nuclear statistical empirical model. The reactions considered are (n,n'), (n,2n), (n,3n), (n,p), (n,d), (n,t), (n, 3 He), (n,α), (n,np), (n,nd), (n,nt), (n,n 3 He), (n,nα), (n,pn), (n,2p), (n,ν), (n,αp), (n,dn) and (n,pα). Most of the above mentioned elements are used as structural materials in nuclear reactors and the measured cross-section data for the above listed reactions are seldom available for the radiation damage and safety analysis. With a view to providing these data, this nuclear model based evaluation has been undertaken. The associated uncertainties in the cross-sections and their fission averages have also been evaluated. (author)

  9. Effect of Mo contents on corrosion behaviors of welded duplex stainless steel

    Science.gov (United States)

    Bae, Seong Han; Lee, Hae Woo

    2013-05-01

    The corrosion behaviour and change of the phase fraction in welded 24Cr Duplex stainless steel was investigated for different chemical composition ranges of Mo contents. Filler metal was produced by fixing the contents of Cr, Ni, N, and Mn while adjusting the Mo content to 0.5, 1.4, 2.5, 3.5 wt%. The δ-ferrite fraction was observed to increase as the content of Mo increased. A polarisation test conducted in a salt solution, indicated the pitting corrosion potential increased continuously to 3.5 wt% Mo, while the corrosion potential changed most between 0.5 and 1.41 wt% Mo. The location of the pitting corrosion in 0.5 wt% Mo steel was randomly distributed, but it occurred selectively at the grain boundary between the γ- and δ-ferrite phases in 1.4, 2.5 and 3.5 wt% Mo steel. Energy dispersive X-ray spectroscopy mapping analysis showed that areas deficient in Cr, Mo, and Ni occurred around the grain boundary of the γ- and δ-ferrite phases. Non-metallic inclusions are thought to act as initiation points for the pitting corrosion that occurs in the salt solution initially as a result of the potential difference between the matrix structure and the incoherent inclusions.

  10. X = S, Se, Te) heterostructures

    KAUST Repository

    Zhang, Qingyun; Schwingenschlö gl, Udo

    2018-01-01

    Using first-principles calculations, we investigate the electronic properties of the two-dimensional GaX/MX2 (M = Mo, W; X = S, Se, Te) heterostructures. Orbital hybridization between GaX and MX2 is found to result in Rashba splitting at the valence

  11. ¿Cómo se traduce el curriculum formal en una experiencia escolar relevante para los alumnos de una escuela telesecundaria de México?

    Directory of Open Access Journals (Sweden)

    José de la luz Sánchez Tepatzi

    2011-01-01

    Full Text Available En este artículo se presenta parte de los resultados obtenidos en una investigación realizada entre los años 2009 y 2010 en una comunidad rural en México donde participaron 12 personas que abandonaron la escuela tele-secundaria. El estudio es de tipo cualitativo y las principales herramientas para obtener la información fueron la historia de vida y la entrevista abierta. La pregunta que orienta este artículo analiza las formas en cómo los alumnos traducen el curriculum formal en una experiencia escolar relevante y cómo influye tal significado en la permanencia. Los principales resultados señalan que la relación profesor-alumno, el trato entre pares y el apoyo de la familia, son elementos importantes para mejorar la permanencia y la calidad de los aprendizajes, así como para otorgar significado relevante a esa experiencia. En las conclusiones del estudio se muestra que el valor positivo hacia la escuela y la relevancia de la experiencia escolar, no son elementos suficientes para garantizar la permanencia, pues en esa decisión intervienen otros factores y razonamientos particulares. Es decir, cada alumno, en su mundo de vida construye un sentido de la realidad y este es el que orienta sus decisiones; una de ellas es permanecer o retirarse de la escuela. En este marco de relativa autonomía, los profesores estamos obligados a ofrecer a los alumnos la oportunidad de vivir una experiencia escolar relevante que les permita desenvolverse en un mundo complejo y aprender a lo largo de la vida, más allá de su condición y disposición para permanecer en la escuela.

  12. Efecto del V y el Si Sobre la Microestructura de Depósitos Realizados con Electrodos Tubulares Revestidos de Alto Contenido de Mn (Hadfield

    Directory of Open Access Journals (Sweden)

    Manuel Rodríguez

    2017-10-01

    Full Text Available Resumen: Las aleaciones para el relleno superficial Fe-Mn-C (Hadfield han demostrado una excelente resistencia al desgaste bajo altas cargas dinámicas. En los últimos años se han realizado numerosos estudios para aumentar la resistencia al desgaste y mejorar su desempeño, a través de la introducción de otros elementos de aleación. En el presente trabajo se investiga la microestructura y dureza de los depósitos de relleno con alto contenido de Mn y adiciones de 1.2% de V y 2.4% de Si. Los depósitos estudiados se realizaron utilizando electrodos tubulares revestidos fabricados a escala de laboratorio. Las fases y microconstituyentes en el metal depositado se identificaron mediante microscopía óptica (MO, electrónica de barrido (MEB, difracción de rayos X (DRX, dureza y microdureza. De acuerdo a los resultados obtenidos, la adición de V al sistema aleante originó que la fase predominante fuera la austenita. Además, contribuyó a la formación de carburos de vanadio (VC en la microestructura de la capa de relleno, sin observarse la presencia de carburos complejos. Por otra parte, la presencia de Si favoreció la formación de una red de ferrita interdendrítica. La adición de estos elementos de aleación mejoró las propiedades de estos depósitos, potencializando su uso en aplicaciones que requieren alta resistencia al desgaste bajo altas cargas.

  13. Selenate as a novel ligand for keplerate chemistry. New {W72Mo60} keplerates with selenates inside the cavity.

    Science.gov (United States)

    Korenev, Vladimir S; Abramov, Pavel A; Vicent, Cristian; Zhdanov, Artem A; Tsygankova, Alphiya R; Sokolov, Maxim N; Fedin, Vladimir P

    2015-05-21

    The synthesis and characterization of three novel keplerate-type compounds containing the {W72Mo60} mixed-metal core are reported. Complexes (NH4)72[{W6O21(H2O)6}12{Mo2O4(SeO4)}30]·150H2O·6(NH4)2SeO4 (1a) and (NH4)25(NH2Me2)47[{W6O21(H2O)6}12{Mo2O4(SeO4)}30]·130H2O·3(NH4)2SeO4 (1b) were prepared by ligand substitution from the acetate anionic complex [{W6O21(H2O)5(CH3COO)0.5}12{Mo2O4(CH3COO)}30](48-) and selenate. The selenate anions in keplerate ions [{W6O21(H2O)6}12{Mo2O4(SeO4)}30](72-) are very labile and easily aquate with the formation of [{W6O21(H2O)6}12{Mo2O4}30(SeO4)20(H2O)20](52-), which was isolated as (NH4)20(NH2Me2)32[{W6O21(H2O)6}12{Mo2O4}30(SeO4)20(H2O)20]·150H2O (2) and structurally characterized. In the crystal structure of 2 selenate has several coordination modes, preferentially bonding to the {Mo2O4}(2+) units, and, additionally, to the {(W)W5} pentagonal blocks. The compounds have been characterized by elemental analysis, Raman, IR and (77)Se NMR spectroscopy, and by ESI mass spectrometry. Capillary electrophoresis was used for characterization of keplerates in solution for the first time.

  14. Essential and toxic element concentrations in monofloral honeys from southern Croatia.

    Science.gov (United States)

    Bilandžić, Nina; Tlak Gajger, Ivana; Kosanović, Marina; Čalopek, Bruno; Sedak, Marija; Solomun Kolanović, Božica; Varenina, Ivana; Luburić, Đurđica Božić; Varga, Ines; Đokić, Maja

    2017-11-01

    The concentrations of 24 elements in seven honey types (multifloral, heather, common heather, bearberry, sage, mandarin orange-blossom and honeydew) collected in southern Mediterranean regions of Croatia were determined using ICP-MS. Significant differences were found in the concentrations of Ag, As, Ba, Cu, Co, Fe, K, Mg, Mn, Mo, Na, Ni, Se, Sb, U and Th (p<0.05, all) among honeys. The highest element concentrations were determined in honeydew honeys, with the exception of multifloral (Ca, Cr, Mo, Se), common heather (Mg, Na), bearberry (Ba, Fe, Pb) and sage (Ag) honeys. Among the floral honeys, the highest concentrations were found in multifloral honey (Al, As, Be, Ca, Cr, Mn, Mo, Ni, Se, Th and U), common heather (Co, K, Mg, Na, V), sage (Ag, Cd, Cu), and bearberry (Ba, Fe, Pb, Sb, Zn). The results contribute to the evidence supporting the role of botanical origin on the elemental composition of honey. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Low-activation Mn-Cr austenitic stainless steel with further reduced content of long-lived radioactive elements

    Energy Technology Data Exchange (ETDEWEB)

    Onozuka, M.; Saida, T.; Hirai, S. [Mitsubishi Heavy Ind. Ltd., Yokohama (Japan); Kusuhashi, M.; Sato, I.; Hatakeyama, T. [The Japan Steel Works Ltd., Chatsu-machi 4, Muroran 051-8505 (Japan)

    1998-06-01

    Low-activation austenitic stainless steel based on Mn-Cr non-magnetic steels has been developed. The alloying elements of long-life activation, such as Ni, Mo and Co, were eliminated and substituted with Mn along with an addition of N. A Mn-Cr austenitic stainless steel, 24.5Mn-13.5Cr-0.02C-0.2N, has been developed successfully. Examined material properties, including mechanical, thermal and magnetic properties, as well as weldability and characteristics of corrosion resistance, are presented. It was found that the alloy has excellent material properties virtually equivalent to those of 316SS. In this study, the applicability of the Schaeffler, DeLong and Hull constitution diagrams for the stainless steels with low Ni and high Mn contents was also examined. The boundary conditions distinguishing the single austenite phase from the others have been identified for the Mn-Cr steels. (orig.) 22 refs.

  16. Low-activation Mn Cr austenitic stainless steel with further reduced content of long-lived radioactive elements

    Science.gov (United States)

    Onozuka, Masanori; Saida, Tomikane; Hirai, Shouzou; Kusuhashi, Mikio; Sato, Ikuo; Hatakeyama, Tsuyoshi

    1998-06-01

    Low-activation austenitic stainless steel based on Mn-Cr non-magnetic steels has been developed. The alloying elements of long-life activation, such as Ni, Mo and Co, were eliminated and substituted with Mn along with an addition of N. A Mn-Cr austenitic stainless steel, 24.5Mn-13.5Cr-0.02C-0.2N, has been developed successfully. Examined material properties, including mechanical, thermal and magnetic properties, as well as weldability and characteristics of corrosion resistance, are presented. It was found that the alloy has excellent material properties virtually equivalent to those of 316SS. In this study, the applicability of the Schaeffler, DeLong and Hull constitution diagrams for the stainless steels with low Ni and high Mn contents was also examined. The boundary conditions distinguishing the single austenite phase from the others have been identified for the Mn-Cr steels.

  17. Cu(InGa)Se{sub 2} absorber formation by in-situ, low-temperature annealing of co-evaporated bilayer (InGa){sub 2}Se{sub 3}/CuSe precursors

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Kyeongchan; Kim, Woo Kyoung, E-mail: wkim@ynu.ac.kr

    2015-12-01

    Chalcopyrite Cu(InGa)Se{sub 2} (CIGS) absorbers were fabricated by the formation of bilayer stacked glass/Mo/(InGa){sub 2}Se{sub 3}/CuSe precursors followed by in-situ thermal annealing at 450 °C for approximately 10 min in a vacuum evaporator. The material properties (e.g., crystal orientation, compositional depth profile, and overall composition) and device performance of the resulting CIGS absorbers were compared with those of the CIGS absorbers formed by conventional 1-stage and 3-stage CIGS formation processes at a similar temperature. X-ray diffraction confirmed that the 1-stage co-evaporation and in-situ annealing of the bilayer precursor produced a polycrystalline CIGS absorber without a specific texture, whereas the CIGS absorber formed by the 3-stage process showed a highly (220) preferred orientation. Secondary ion mass spectrometry revealed Ga accumulation at the bottom of CIGS formed by in-situ annealing of the bilayer precursors. The cell efficiency of the device with the CIGS absorber formed by the in-situ, low-temperature (450 °C) annealing of bilayer stacked glass/Mo/(InGa){sub 2}Se{sub 3}/CuSe precursors was comparable to that produced by the conventional 3-stage process at a similar temperature. - Highlights: • Annealing of (InGa){sub 2}Se{sub 3}/CuSe precursors was compared with coevaporation process. • In-situ annealing of (InGa){sub 2}Se{sub 3}/CuSe precursors at 450 °C produced about 9% solar cell. • Ga profile within Cu(InGa)Se{sub 2} depended on process profile during co-evaporation.

  18. Microstructural Influence on Dynamic Properties of Age Hardenable FeMnAl Alloys

    Science.gov (United States)

    2011-04-01

    strain amplitude on a wrought Fe-28Mn-9Al-0.86C-0.7W-0.43Mo-0.49Nb alloy and on a martensitic stainless steel of composition Fe-12Cr-1.25Ni-0.2V-1.8W...the martensite and loss of strength was used to explain the lower cyclic life of the stainless steel at elevated temperatures. Within the Fe-Mn-Al-C...through F in Table 2), 1010 carbon steel and 304 stainless steel as functions of exposure time in 1 atm flowing oxygen at 700°C (a) and 500°C (b).56

  19. Application of concentration-volume fractal method in induced polarization and resistivity data interpretation for Cu-Mo porphyry deposits exploration, case study: Nowchun Cu-Mo deposit, SE Iran

    Directory of Open Access Journals (Sweden)

    L. Daneshvar Saein

    2012-08-01

    Full Text Available The aim of this study is the utilization of the concentration-volume (C-V fractal method based on geoelectrical data including induced polarization (IP and resistivity (RS in targeting areas hosting different sulfidic mineralization zones in Nowchun Cu-Mo porphyry deposit, SE Iran. The C-V fractal model employed in this research in order to separate high and moderate sulfidic zones from low sulfidic zone and barren wall rocks in the deposit is corresponding to chargeability and resistivity. Results obtained from the C-V method indicate that there is a positive correlation between subsurface mineralization and sulfide mineralized zones; additionally, use of the C-V method based on geophysical data is recognized as an accurate approach for delineation of various mineralization zones in the depth for optimization of mineral exploration operation, particularly in porphyry deposits.

  20. Synthesis and structural, spectroscopic and magnetic studies of two new polymorphs of Mn(SeO3).H2O

    International Nuclear Information System (INIS)

    Larranaga, Aitor; Mesa, Jose L.; Pizarro, Jose L.; Pena, A.; Olazcuaga, Roger; Arriortua, Maria I.; Rojo, Teofilo

    2005-01-01

    Two new manganese(II) selenite polymorphs with formula Mn(SeO 3 ).H 2 O have been synthesized by slow evaporation from an aqueous solution. The crystal structure of both compounds (1) and (2) have been solved from X-ray diffraction data. The structure of (1) was determined from single-crystal X-ray diffraction techniques. The compound crystallizes in the Ama2 space group, with a=5.817(1), b=13.449(3), c=4.8765(9)A and Z=4. The structure of (2) has been solved from X-ray powder diffraction data. This phase crystallizes in the P2 1 /n space group with unit-cell parameters of a=4.921(3), b=13.121(7), c=5.816(1)A, β=90.03(2) o and Z=4. Both polymorphs exhibit a layered structure formed by isolated sheets of MnO 6 octahedra and (SeO 3 ) 2- trigonal pyramids in the (010) plane. These layers, which contain one manganese and selenium atom crystallographically independent, are formed by octahedra linked between them through the selenite oxoanions. The difference of both compounds consists in the stacking of the layers along the b-axis. The IR spectra show the characteristic bands of the selenite anion. Studies of luminescence performed at 6K and diffuse reflectance spectroscopy have been carried out for both phases. The Dq and Racah (B and C) parameters, from luminescence and diffuse reflectance spectroscopy, are Dq=705, B=750, C=3325cm -1 for (1) and Dq=720, B=745, C=3350cm -1 for (2). The ESR spectra of both compounds are isotropic with g-values of 1.99(1). Magnetic measurements indicate the presence of antiferromagnetic couplings in both phases. The J-exchange parameters have been estimated by fitting the experimental magnetic data to a model for square-planar lattice. The values obtained are J/k=-0.83, -0.91K and J ' /k=-0.97, -1.20K, for polymorphs (1) and (2), respectively

  1. Single-Nanoflake Photo-Electrochemistry Reveals Champion and Spectator Flakes in Exfoliated MoSe2 Films

    Energy Technology Data Exchange (ETDEWEB)

    Link, Elisa M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nanayakkara, Sanjini U [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Todt, Michael A. [Colorado State University; Isenberg, Allan E. [Colorado State University; Sambur, Justin B. [Colorado State University

    2018-03-06

    Semiconducting transition-metal dichalcogenide (TMD) nanoflake thin films are promising large-area electrodes for photo-electrochemical solar energy conversion applications. However, their energy conversion efficiencies are typically much lower than those of bulk electrodes. It is unclear to what extent this efficiency gap stems from differences among nanoflakes (e.g., area, thickness, and surface structural features). It is also unclear whether individual exfoliated nanoflakes can achieve energy conversion efficiencies similar to those of bulk crystals. Here, we use a single-nanoflake photo-electrochemical approach to show that there are both highly active and completely inactive nanoflakes within a film. For the exfoliated MoSe2 samples studied herein, 7% of nanoflakes are highly active champions, whose photocurrent efficiency exceeds that of the bulk crystal. However, 66% of nanoflakes are inactive spectators, which are mostly responsible for the overall lower photocurrent efficiency compared to the bulk crystal. The photocurrent collection efficiency increases with nanoflake area and decreases more at perimeter edges than at interior step edges. These observations, which are hidden in ensemble-level measurements, reveal the underlying performance issues of exfoliated TMD electrodes for photo-electrochemical energy conversion applications.

  2. ¿Cómo hacer ficciones con ficciones?

    Directory of Open Access Journals (Sweden)

    Jimena Garrido

    2017-01-01

    Full Text Available Este escrito responde a la invitación a pensar cómo el arte puede colaborar en procesos de reconstitución de lazos sociales. Para ello, propongo retomar reflexiones y experiencias en torno a cómo en específico el campo teatral participa en transformaciones sociales. Por un lado, el trabajo recupera los estudios de la vida social como actuación y, en particular, se detiene a pensar las nociones de personajes, tensiones y extrañezas para el análisis social. Luego, se recitan experiencias del campo teatral las cuales se ocuparon de indagar en la dimensión transformadora de este arte. El propósito es armarnos de herramientas que nos permitan desmontar ficciones de larga duración y trazar propuestas para captar imaginaciones que llegan con los relámpagos. Palabras clave: teatro, performance, personaje, conflicto, extrañar.

  3. Thickness-dependent magneto-optical effects in hole-doped GaS and GaSe multilayers: a first-principles study

    Science.gov (United States)

    Li, Fei; Zhou, Xiaodong; Feng, Wanxiang; Fu, Botao; Yao, Yugui

    2018-04-01

    Recently, two-dimensional (2D) GaS and GaSe nanosheets were successfully fabricated and the measured electronic, mechanical, and optoelectronic properties are excellent. Here, using the first-principles density functional theory, we investigate the magnetic, optical, and magneto-optical (MO) Kerr and Faraday effects in hole-doped GaS and GaSe multilayers. GaS and GaSe monolayers (MLs) manifest ferromagnetic ground states by introducing even a small amount of hole doping, whereas the magnetism in GaS and GaSe multilayers are significantly different under hole doping. Our results show that ferromagnetic states can be easily established in GaS bilayers and trilayers under proper hole doping, however, most of GaSe multilayers are more favorable to nonmagnetic states. The magnetic moments in GaS multilayers are weakened remarkably with the increasing of thin film thickness and are negligible more than three MLs. This leads to the thickness dependence of MO Kerr and Faraday effects. Furthermore, the MO effects strongly depend on the doping concentration and therefore are electrically controllable by adjusting the number of holes via gate voltage. The substrate effects on the MO properties are also discussed. Combining the unique MO and other interesting physical properties make GaS and GaSe a superior 2D material platform for semiconductor MO and spintronic nanodevices.

  4. The effects of the local fracture stress and carbides on the cleavage fracture characteristics of Mn-Mo-Ni low alloy steels in the transition region

    International Nuclear Information System (INIS)

    Yang, Won Jon; Huh, Moo Young; Roh, Sung Joo; Lee, Bong Sang; Oh, Yong Jun; Hong, Jun Hwa

    2000-01-01

    In the ductile-brittle transition temperature region of SA508 C1.3 Mn-Mo-Ni low alloy steels, the relationship of the local fracture stress and carbides influencing the cleavage fracture behavior was investigated. Based on the ASTM E1921-97 standard method, the reference transition temperatures were determined by three point bending fracture toughness tests. A local fracture stress σ f * , was determined from a theoretical stress distribution in front of crack tip using the cleavage initiation distance measured in each fractured specimen surface. The local fracture stress values showed a strong relationship with toughness characteristics of the materials and those were larger in the materials of smaller carbide size. Quantitative analysis of carbides showed that carbides larger than a certain size are mainly responsible for the cleavage fracture in the ductile-brittle transition temperature region. (author)

  5. α-MoO3 thin films prepared by spray pyrolysis Películas delgadas de α-MoO3 preparadas por atomización pirolítica

    Directory of Open Access Journals (Sweden)

    L D López-Carreño

    2011-12-01

    Full Text Available MoO3 thin films have been deposited on clean glass slides using the spray pyrolysis technique. The samples were grown with different thicknesses by spraying on common glass substrates a solution of(ammoniummolybdatetetrahydrate ((NH36Mo7O244H2O. The samples were characterized by X-ray diffraction (XRD, infrared spectroscopy, scanning electron microscopy (SEM and electrically through electrical resistivity measurements as a function of temperature. It was found that samples present crystalline structure associated with the alpha phase of MoO3 grown with preferential direction of growth along the planes (0k0. As result of increasing the volume of precursor solution sample surface becomes porous. The change in electrical resistance of MoO3 films by exposure to carbon monoxide (CO at room temperature, makes the films obtained by this technique could be promising in its use in gas sensing devices at room temperature.En este trabajo se prepararon películas delgadas de trióxido de molibdeno (MoO3 por la técnica de atomización pirolítica. Las películas fueron depositadas sobre sustratos de vidrio y obtenidas a partir de una solución precursora de Heptamolibdato de Amonio Tetrahidratado ((NH36Mo7O24.4H2O 0.1 M. La temperatura del sustrato se mantuvo constante en 400 oC y se varío el volumen de la solución precursora. Las muestras se caracterizaron por difracción de Rayos X (XRD, espectroscopía infrarroja, Microscopía Electrónica de Barrido (SEM y eléctricamente a través de medidas de resistividad eléctrica en función de la temperatura. Las muestras crecen con estructura cristalina correspondiente a la fase alfa del MoO3 con dirección preferencial de crecimiento a lo largo de los planos (0k0. Al aumentar el volumen de la solución precursora la superficie de las muestras se vuelve porosa. La resistividad en estas muestras cambia en un orden de magnitud cuando son expuestas a la atmosfera de CO.

  6. Mis colaboradores no se comprometen con la empresa y sus objetivos

    OpenAIRE

    Vega Jimenez, Mabel Angelica

    2017-01-01

    La tesis plantea cómo se hace que el ser personal emerja del ser humano en una empresa u organización, y se comprometa y una al propósito o misión de la organización y sus dueños; cómo se hace que una empresa desarrolle y fortalezca su entraña empresarial. De qué manera pueden los gerentes contribuir con esta gran misión de lograr unidad y alcanzar metas con una "diversidad" humana interactuando unos con otros, cuando la dirección solo mira y exige metas. Trabajo de investigación

  7. ¿Como se hace publicidad por internet?

    Directory of Open Access Journals (Sweden)

    Franz Del Pozo

    2015-01-01

    Full Text Available Internet es el medio de comunicación y venta con el mayor potencial de crecimiento y efectividad al más bajo precio. Para vender se usan tarjetas de crédito, depósitos bancarios, franqueo, comercio electrónico. Explica qué y cómo se hace publicidad por Internet. La Red se usa para difundir y para vender y hay la posibilidad de hacer algo diferente a más de llegar directamente al público objetivo se interactúa con él.

  8. Transition metal atoms absorbed on MoS2/h-BN heterostructure: stable geometries, band structures and magnetic properties.

    Science.gov (United States)

    Wu, Yanbing; Huang, Zongyu; Liu, Huating; He, Chaoyu; Xue, Lin; Qi, Xiang; Zhong, Jianxin

    2018-06-15

    We have studied the stable geometries, band structures and magnetic properties of transition-metal (V, Cr, Mn, Fe, Co and Ni) atoms absorbed on MoS2/h-BN heterostructure systems by first-principles calculations. By comparing the adsorption energies, we find that the adsorbed transition metal (TM) atoms prefer to stay on the top of Mo atoms. The results of the band structure without spin-orbit coupling (SOC) interaction indicate that the Cr-absorbed systems behave in a similar manner to metals, and the Co-absorbed system exhibits a half-metallic state. We also deduce that the V-, Mn-, Fe-absorbed systems are semiconductors with 100% spin polarization at the HOMO level. The Ni-absorbed system is a nonmagnetic semiconductor. In contrast, the Co-absorbed system exhibits metallic state, and the bandgap of V-absorbed system decreases slightly according to the SOC calculations. In addition, the magnetic moments of all the six TM atoms absorbed on the MoS2/h-BN heterostructure systems decrease when compared with those of their free-standing states.

  9. Thermal expansion, anharmonicity and temperature-dependent Raman spectra of single- and few-layer MoSe₂ and WSe₂.

    Science.gov (United States)

    Late, Dattatray J; Shirodkar, Sharmila N; Waghmare, Umesh V; Dravid, Vinayak P; Rao, C N R

    2014-06-06

    We report the temperature-dependent Raman spectra of single- and few-layer MoSe2 and WSe2 in the range 77-700 K. We observed linear variation in the peak positions and widths of the bands arising from contributions of anharmonicity and thermal expansion. After characterization using atomic force microscopy and high-resolution transmission electron microscopy, the temperature coefficients of the Raman modes were determined. Interestingly, the temperature coefficient of the A(2)(2u) mode is larger than that of the A(1g) mode, the latter being much smaller than the corresponding temperature coefficients of the same mode in single-layer MoS2 and of the G band of graphene. The temperature coefficients of the two modes in single-layer MoSe2 are larger than those of the same modes in single-layer WSe2. We have estimated thermal expansion coefficients and temperature dependence of the vibrational frequencies of MoS2 and MoSe2 within a quasi-harmonic approximation, with inputs from first-principles calculations based on density functional theory. We show that the contrasting temperature dependence of the Raman-active mode A(1g) in MoS2 and MoSe2 arises essentially from the difference in their strain-phonon coupling. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Linking AS, SE, V, and MN Behavior to Natural Biostimulated Uranium Cycling

    Energy Technology Data Exchange (ETDEWEB)

    Keimowitz, Alison [Vassar College, Poughkeepsie, NY (United States); Ranville, James [Colorado School of Mines, Golden, CO (United States); Mailloux, Brian [Barnard College, New York, NY (United States); Figueroa, Linda [Colorado School of Mines, Golden, CO (United States)

    2016-03-16

    The project “Linking As, Se, V, and Mn behavior to Natural and Biostimulated Uranium Cycling” successfully investigated Arsenic cycling the Rifle Colorado IFRC. This project trained undergraduate and graduate students at the Colorado School of Mines, Vassar College, and Barnard College. This resulted in both undergraduate theses and a PhD thesis and multiple publications. The science was highly successful and we were able to test the main hypotheses. We have shown that (H1) under reducing conditions that promote uranium immobilization arsenic is readily mobilized, that (H2) thioarsenic species are abundant during this mobilization, and (H3) we have examined arsenic mobilization for site sediment. At the Rifle IFRC Acetate was added during experiments to immobilize Uranium. These experiments successfully immobilized uranium but unfortunately would mobilize arsenic. We developed robust sampling and analysis methods for thioarsenic species. We showed that the mobilization occurred under sulfate reducing conditions and the majority of the arsenic was in the form of thioarsenic species. Previous studies had predicted the presence of thioarsenic species but this study used robust field and laboratory methods to quantitatively determine the presence of thioarsenic species. During stimulation in wells with high arsenic the primary species were trithioarsenate and dithioarsenate. In wells with low levels of arsenic release thioarsenates were absent or minor components. Fortunately after the injection of acetate ended the aquifer would become less reducing and the arsenic concentrations would decrease to pre-injection levels. In aquifers where organic carbon is being added as a remedial method or as a contaminant the transient mobility of arsenic during sulfidogenesis should be considered especially in sulfate rich aquifers as this could impact downgradient water quality.

  11. Unexpected strong magnetism of Cu doped single-layer MoS₂ and its origin.

    Science.gov (United States)

    Yun, Won Seok; Lee, J D

    2014-05-21

    The magnetism of the 3d transition-metal (TM) doped single-layer (1L) MoS2, where the Mo atom is partially replaced by the 3d TM atom, is investigated using the first-principles density functional calculations. In a series of 3d TM doped 1L-MoS2's, the induced spin polarizations are negligible for Sc, Ti, and Cr dopings, while the induced spin polarizations are confirmed for V, Mn, Fe, Co, Ni, Cu, and Zn dopings and the systems become magnetic. Especially, the Cu doped system shows unexpectedly strong magnetism although Cu is nonmagnetic in its bulk state. The driving force is found to be a strong hybridization between Cu 3d states and 3p states of neighboring S, which results in an extreme unbalanced spin-population in the spin-split impurity bands near the Fermi level. Finally, we also discuss further issues of the Cu induced magnetism of 1L-MoS2 such as investigation of additional charge states, the Cu doping at the S site instead of the Mo site, and the Cu adatom on the layer (i.e., 1L-MoS2).

  12. Behavior of Electrochemically Prepared CuInSe2 as Photovoltaic Absorber in thin Film Solar Cells

    International Nuclear Information System (INIS)

    Guillen, C; Martinez, M.A.; Dona, J. M.; Herrero, J; Gutierrez, M. T.

    2000-01-01

    Two different objectives have been pursued in the present investigation: 1) optimization of the CuInSe, preparation parameters from electrodeposited precursors, and 2) evaluation of their photovoltaic behavior by preparing and enhancing Mo/CuInSe,/CdS/TCO devices. When Cu-In-Se precursors are directly electrodeposited, the applied potential fit is essential to improve the photovoltaic performance. Suitable absorbers have been also obtained by evaporating an In layer onto electrodeposited Cu-Se precursors. In this case, the substrate temperature during evaporation determines the CuInSe, quality. Similar results have been reached by substituting typical Mo-coated glass substrates by flexible Mo foils. Different TCO tested (ZnO and ITO) have been found equivalent as front electrical contact in the devices. Solar cell performance can be improved by annealing in air at 200 degree centigree. (Author) 46 refs

  13. Spin diffusion in the Mn2+ ion system of II-VI diluted magnetic semiconductor heterostructures

    Science.gov (United States)

    Maksimov, A. A.; Yakovlev, D. R.; Debus, J.; Tartakovskii, I. I.; Waag, A.; Karczewski, G.; Wojtowicz, T.; Kossut, J.; Bayer, M.

    2010-07-01

    The magnetization dynamics in diluted magnetic semiconductor heterostructures based on (Zn,Mn)Se and (Cd,Mn)Te were studied optically and simulated numerically. In samples with inhomogeneous magnetic ion distribution, these dynamics are contributed by spin-lattice relaxation and spin diffusion in the Mn spin system. A spin-diffusion coefficient of 7×10-8cm2/s was evaluated for Zn0.99Mn0.01Se from comparison of experiment and theory. Calculations of the exciton giant Zeeman splitting and the magnetization dynamics in ordered alloys and digitally grown parabolic quantum wells show perfect agreement with the experimental data. In both structure types, spin diffusion contributes essentially to the magnetization dynamics.

  14. Development of banded microstructure in 34CrNiMo6 steel

    Directory of Open Access Journals (Sweden)

    A. Nagode

    2016-07-01

    Full Text Available In this paper the development of a banded microstructure in hot-rolled 34CrNiMo6 steel which consisted of bainitic and martensitic bands is explained. The chemical compositions of the bands were measured with energy dispersive x-ray spectroscopy (EDS, which showed that the martensitic bands contained more alloying elements (Mn, Cr, Mo, Si than bainitic bands. By using Oberhoffer reagent, the segregations of phosphorus were also revealed. These phosphorus segregations coincided with the positive segregations of the alloying elements. The continuous cooling transformation (CCT diagrams of steel were calculated. They confirmed the formation of martensite in positive segregations and the formation of bainite in negative segregations.

  15. Spectrographic determination of impurities in ammonium bifluoride. IV.Study of the processes of vaporization, transport and excitation of the elements Fe, Mn, Mo, Ni, Pb and Si

    International Nuclear Information System (INIS)

    Alduan, F.A.; Capdevila, C.; Roca, M.

    1981-01-01

    The influences of the processes of vaporization, transport and excitation on the shape of the volatilization-excitation curves and on the values of the spectra-line intensities have been investigated in a method for the spectrographic determination of Fe, Mn, Mo, Ni, Pb and Si in ammonium bifluoride samples by direct current arc Ga 2 O 3 , GeO 2 , MgO and ZnO. The reaction products in the electrode cavity have been identified by X-ray powder diffraction analysis and the porcentages of vaporized and diffused element evaluated through analysis by total-burning spectrographic methods. In addition, the values of both the number of particles entering the discharge column and the transport efficiencies have been calculated. Thus, the origin of most observed differences has been explained. (author)

  16. ¿Cómo se leen los números?

    Directory of Open Access Journals (Sweden)

    Pedro Macizo

    2012-07-01

    Full Text Available En los modelos de procesamiento numérico se asume que para llegar a la información fonológica que nos permite nombrar un dígito arábigo como “3”, tenemos que acceder previamente a su significado (la cantidad 3. Esto no es necesario cuando leemos una palabra numérica como “tres”, pues podemos pronunciarla sin entender a qué cantidad se refiere. Pero nuestro equipo ha mostrado recientemente que tanto la denominación de dígitos arábigos como la lectura de palabras numéricas pueden realizarse sin acceder al significado. Creemos que el acceso directo a la fonología en el caso de los dígitos arábigos podría derivarse del aprendizaje temprano y de la frecuencia de uso de este tipo de símbolos numéricos.

  17. Evaluation of precision and accuracy of neutron activation analysis method of environmental samples analysis

    International Nuclear Information System (INIS)

    Wardani, Sri; Rina M, Th.; L, Dyah

    2000-01-01

    Evaluation of precision and accuracy of Neutron Activation Analysis (NAA) method used by P2TRR performed by analyzed the standard reference samples from the National Institute of Environmental Study of Japan (NIES-CRM No.10 (rice flour) and the National Bureau of USA (NBS-SRM 1573a (tomato leave) by NAA method. In analyze the environmental SRM No.10 by NAA method in qualitatively could identified multi elements of contents, namely: Br, Ca, Co, CI, Cs, Gd, I, K< La, Mg, Mn, Na, Pa, Sb, Sm, Sr, Ta, Th, and Zn (19 elements) for SRM 1573a; As, Br, Cr, CI, Ce, Co, Cs, Fe, Ga, Hg, K, Mn, Mg, Mo, Na, Ni, Pb, Rb, Sr, Se, Sc, Sb, Ti, and Zn, (25 elements) for CRM No.10a; Ag, As, Br, Cr, CI, Ce, Cd, Co, Cs, Eu, Fe, Ga, Hg, K, Mg, Mn, Mo, Na, Nb, Pb, Rb, Sb, Sc, Th, TI, and Zn, (26 elements) for CRM No. 10b; As, Br, Co, CI, Ce, Cd, Ga, Hg, K, Mn, Mg, Mo, Na, Nb, Pb, Rb, Sb, Se, TI, and Zn (20 elementary) for CRM No.10c. In the quantitatively analysis could determined only some element of sample contents, namely: As, Co, Cd, Mo, Mn, and Zn. From the result compared with NIES or NBS values attained with deviation of 3% ∼ 15%. Overall, the result shown that the method and facilities have a good capability, but the irradiation facility and the software of spectrometry gamma ray necessary to developing or seriously research perform

  18. Probing Anisotropic Thermal Conductivity of Transition Metal Dichalcogenides MX2 (M = Mo, W and X = S, Se) using Time-Domain Thermoreflectance.

    Science.gov (United States)

    Jiang, Puqing; Qian, Xin; Gu, Xiaokun; Yang, Ronggui

    2017-09-01

    Transition metal dichalcogenides (TMDs) are a group of layered 2D semiconductors that have shown many intriguing electrical and optical properties. However, the thermal transport properties in TMDs are not well understood due to the challenges in characterizing anisotropic thermal conductivity. Here, a variable-spot-size time-domain thermoreflectance approach is developed to simultaneously measure both the in-plane and the through-plane thermal conductivity of four kinds of layered TMDs (MoS 2 , WS 2 , MoSe 2 , and WSe 2 ) over a wide temperature range, 80-300 K. Interestingly, it is found that both the through-plane thermal conductivity and the Al/TMD interface conductance depend on the modulation frequency of the pump beam for all these four compounds. The frequency-dependent thermal properties are attributed to the nonequilibrium thermal resistance between the different groups of phonons in the substrate. A two-channel thermal model is used to analyze the nonequilibrium phonon transport and to derive the intrinsic thermal conductivity at the thermal equilibrium limit. The measurements of the thermal conductivities of bulk TMDs serve as an important benchmark for understanding the thermal conductivity of single- and few-layer TMDs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Doping Li-rich cathode material Li2MnO3 : Interplay between lattice site preference, electronic structure, and delithiation mechanism

    Science.gov (United States)

    Hoang, Khang

    2017-12-01

    We report a detailed first-principles study of doping in Li2MnO3 , in both the dilute doping limit and heavy doping, using hybrid density-functional calculations. We find that Al, Fe, Mo, and Ru impurities are energetically most favorable when incorporated into Li2MnO3 at the Mn site, whereas Mg is most favorable when doped at the Li sites. Nickel, on the other hand, can be incorporated at the Li site and/or the Mn site, and the distribution of Ni over the lattice sites can be tuned by tuning the material preparation conditions. There is a strong interplay among the lattice site preference and charge and spin states of the dopant, the electronic structure of the doped material, and the delithiation mechanism. The calculated electronic structure and voltage profile indicate that in Ni-, Mo-, or Ru-doped Li2MnO3 , oxidation occurs on the electrochemically active transition-metal ion(s) before it does on oxygen during the delithiation process. The role of the dopants is to provide charge compensation and bulk electronic conduction mechanisms in the initial stages of delithiation, hence enabling the oxidation of the lattice oxygen in the later stages. This work thus illustrates how the oxygen-oxidation mechanism can be used in combination with the conventional mechanism involving transition-metal cations in design of high-capacity battery cathode materials.

  20. High temperature corrosion behaviour of Ti-46.6Al-1.4Mn-2Mo in environments of low oxygen and high sulphur potentials at 750 and 900 C

    International Nuclear Information System (INIS)

    Du, H.L.; Datta, P.K.; Hwang, S.K.

    1997-01-01

    In this paper, the oxidation and sulphidation behaviour of a TiAl-based intermetallic, Ti-46.6Al-1.4Mn-2Mo (at%) with duplex and laminar microstructures, was investigated in environments of H 2 /H 2 S/H 2 O at 750 and 900 C. The corrosion kinetics of the intermetallic were determined by means of discontinuous gravimetry and the as-received and exposed samples were characterised using SEM, EDX and XRD. The weight gain/time data in the oxygen and sulphur containing environment used indicated parabolic kinetics with Kp∝10 -12 g 2 /cm 4 /s at 750 C and cubic kinetics at 900 C. The increase in exposure temperature did not significantly change the corrosion behaviour of the materials. The material showed the development of a multilayered scale consisting of an outermost TiO 2 layer beneath which an Al 2 O 3 layer existed: the formation of MnS and Al 2 S 3 was observed to occur between the oxide layers and substrate. This paper will discuss the significance of these results and consider the mechanisms responsible for degradation of this type of intermetallics in high sulphur and low oxygen environment with reference to their limit of temperature tolerance. (orig.)

  1. Investigation on the electrochemical activation process of Li1.20Ni0.32Co0.004Mn0.476O2

    Directory of Open Access Journals (Sweden)

    Daichun Tang

    2014-08-01

    Full Text Available The lithium-rich layered oxides are one of the most attractive cathode materials for lithium-ion batteries. Here, two types of Li1.20Ni0.32Co0.004Mn0.476O2 were synthesized using Li2CO3 and LiOH as lithium sources. An electrochemical activation process occurs in Li1.2Ni0.32Co0.004Mn0.476O2 prepared from Li2CO3 (LLO-1, while no obvious activation in Li1.2Ni0.32Co0.004Mn0.476O2 prepared from LiOH (LLO-2 is observed. Via advanced scanning transmission electron microscopy (STEM, we found that Li2MnO3-like structure is rich in the surface region of LLO-2. The study provides a direct explanation for the electrochemical activation of lithium-rich materials. The sample with more LiMO2-like phase at the surface region shows a better cycling performance. It is likely that more LiMO2-like phase at the surface region could stabilize the interface and improve the cycling performance of the Li-rich cathode materials.

  2. Behavior of Electrochemically Prepared CuInSe{sub 2} as Photovoltaic Absorber in thin Film Solar Cells; Comportamiento del CuInSe{sub 2} Basado en Precursores Electrodepositados como Absorbente Fotovoltaico en Celulas Solares de Lamina Delgada

    Energy Technology Data Exchange (ETDEWEB)

    Guillen, C; Martinez, M A; Dona, J M; Herrero, J; Gutierrez, M T [Ciemat.Madrid (Spain)

    2000-07-01

    Two different objective have been pursued in the present investigation: (1) optimization of the CuInSe{sub 2} preparation parameters from electrodeposited precursors, and (2) evaluation of their photovoltaic behavior by preparing and enhancing Mo/CuInSe{sub 2}/CdS/TCO devices. When Cu-In-Se precursors are directly electrodeposited, the applied potential fit is essential to improve the photovoltaic performance. Suitable absorbers have been also obtained by evaporing an In layer onto electrodeposited Cu-Se precursors. In this case, the substrate temperature during evaporation determines the CuInSe{sub 2} quality. Similar results have been reached by substituting typical Mo-Coated glass substrates by flexible Mo foils. Different TCO tested (ZnO and ITO) have been found equivalent as front electrical contact in the devices. Solar cell performance can be improved by annealing in air at 200 degree centigree. (Author) 46 refs.

  3. In situ DRIFTs investigation of the reaction mechanism over MnO{sub x}-MO{sub y}/Ce{sub 0.75}Zr{sub 0.25}O{sub 2} (M = Fe, Co, Ni, Cu) for the selective catalytic reduction of NO{sub x} with NH{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Hang; Zha, Kaiwen; Li, Hongrui; Shi, Liyi; Zhang, Dengsong, E-mail: dszhang@shu.edu.cn

    2016-11-30

    Highlights: • MnO{sub x}-FeO{sub y}/Ce{sub 0.75}Zr{sub 0.25}O{sub 2} catalyst has a strong NO oxidation ability. • A high dispersion of active components is achieved on catalyst surface. • At high temperatures, bidentate nitrate is the common active species. • The addition of Fe can improve the reactivity of gaseous NO{sub 2} and bridged nitrates. - Abstract: A series of MnO{sub x}-MO{sub y}/Ce{sub 0.75}Zr{sub 0.25}O{sub 2} (M = Fe, Co, Ni, Cu) catalysts were synthesized by an impregnation method and used for selective catalytic reduction (SCR) of NO{sub x} with NH{sub 3}. The catalytic performances of various MnO{sub x}-MO{sub y}/Ce{sub 0.75}Zr{sub 0.25}O{sub 2} catalysts were studied. It was found that MnO{sub x}-FeO{sub y}/Ce{sub 0.75}Zr{sub 0.25}O{sub 2} catalyst showed excellent low-temperature activity and a broad temperature window. The catalysts were characterized by N{sub 2} adsorption/desorption, X-ray diffraction, X-ray photoelectron spectroscopy and in situ diffuse reflectance infrared transform spectroscopy (DRIFTS). Characterization of the catalyst confirmed the addition of iron oxide can enhance the NO oxidation ability of the catalyst which results in the outstanding low-temperature SCR activity. Meanwhile, iron oxides were well dispersed on catalyst surface which could avoid the agglomeration of active species, contributing to the strong interaction between active species and the support. More importantly, in situ DRIFTS results confirmed that bidentate nitrates are general active species on these catalysts, whereas the reactivity of gaseous NO{sub 2} and bridged nitrates got improved because of the addition of Fe.

  4. ¿Se puede recobrar el capital invertido en participaciones preferentes?

    Directory of Open Access Journals (Sweden)

    Gómez Hernández, José Antonio

    2013-01-01

    Full Text Available En este trabajo se analiza qué son las participaciones preferentes, cómo y por qué se han comercializado en España y las diversas posibilidades que ofrece el ordenamiento jurídico para intentar recuperar el capital desembolsado.

  5. Chalcogenidobis(ene-1,2-dithiolate)molybdenum(IV) complexes (chalcogenide E = O, S, Se): probing Mo≡E and ene-1,2-dithiolate substituent effects on geometric and electronic structure.

    Science.gov (United States)

    Sugimoto, Hideki; Tano, Hiroyuki; Suyama, Koichiro; Kobayashi, Tomoya; Miyake, Hiroyuki; Itoh, Shinobu; Mtei, Regina P; Kirk, Martin L

    2011-02-07

    New square-pyramidal bis(ene-1,2-dithiolate)MoSe complexes, [Mo(IV)Se(L)(2)](2-), have been synthesised along with their terminal sulfido analogues, [Mo(IV)S(L)(2)](2-), using alkyl (L(C(4)H(8))), phenyl (L(Ph)) and methyl carboxylate (L(COOMe)) substituted dithiolene ligands (L). These complexes now complete three sets of Mo(IV)O, Mo(IV)S and Mo(IV)Se species that are coordinated with identical ene-1,2-dithiolate ligands. The [alkyl substituted Mo(S/Se)(L(C(4)H(8)))(2)](2-) complexes were reported in prior investigations (H. Sugimoto, T. Sakurai, H. Miyake, K. Tanaka and H. Tsukube, Inorg. Chem. 2005, 44, 6927, H. Tano, R. Tajima, H. Miyake, S. Itoh and H. Sugimoto, Inorg. Chem. 2008, 47, 7465). The new series of complexes enable a systematic investigation of terminal chalcogenido and supporting ene-1,2-dithiolate ligand effects on geometric structure, electronic structure, and spectroscopic properties. X-ray crystallographic analysis of these (Et(4)N)(2)[MoEL(2)] (E = terminal chalocogenide) complexes reveals an isostructural Mo centre that adopts a distorted square pyramidal geometry. The M≡E bond distances observed in the crystal structures and the ν(M≡E) vibrational frequencies indicate that these bonds are weakened with an increase in L→Mo electron donation (L(COOMe) < L(Ph) < L(C(4)H(8))), and this order is confirmed by an electrochemical study of the complexes. The (77)Se NMR resonances in MoSeL complexes appear at lower magnetic fields as the selenido ion became less basic from MoSeL(C(4)H(8)), MoSeL(Ph) and MoSeL(COOMe). Electronic absorption and resonance Raman spectroscopies have been used to assign key ligand-field, MLCT, LMCT and intraligand CT bands in complexes that possess the L(COOMe) ligand. The presence of low-energy intraligand CT transition in these MoEL(COOMe) compounds directly probes the electron withdrawing nature of the -COOMe substituents, and this underscores the complex electronic structure of square pyramidal bis(ene-1

  6. Stability and magnetic properties of SnSe monolayer doped by transition metal atom (Mn, Fe, and Co): a first-principles study

    Science.gov (United States)

    Tang, Chao; Li, Qinwen; Zhang, Chunxiao; He, Chaoyu; Li, Jin; Ouyang, Tao; Li, Hongxing; Zhong, Jianxin

    2018-06-01

    Two dimensional (2D) tin selenium (SnSe) is an intriguing material with desired thermal and electric properties in nanoelectronics. In this paper, we carry on a density functional theory study on the stability and dilute magnetism of the 3d TM (Mn, Fe, and Co) doped 2D SnSe. Both the adsorption and substitution are in consideration here. We find that all the defects are electrically active and the cation substitutional doping (TM@Sn) is energetically favorable. The TM@Sn prefers to act as accepters and exhibits high-spin state with nonzero magnetic moment. The magnetic moment is mainly contributed by the spin-polarized charge density of the TM impurities. The magnetism is determined by the arrangement of the TM-3d orbitals, which is the result of the crystal field splitting and spin exchange splitting under specific symmetry. The magnetic and electronic properties of the TM@Sn are effectively modulated by external electric field (Eext) and charge doping. The Eext shifts the TM impurities relative to the SnSe host and then modifies the crystal field splitting. In particular, the magnetic moment is sensitive to the Eext in the Fe@Sn because the Eext induces distinct structure transformation. Based on the formation energy, doping electrons is a viable way to modulate the magnetic moment of TM@Sn. Doping electrons shift the 3d states towards low energy level, which induces the occupation of more 3d states and then the reduction of magnetism. These results render SnSe monolayer a promising 2D material for applications in future spintronics.

  7. High pressure phase transition and anharmonic properties of Zn1-xMxSe (M=Cd, Fe and Mn) diluted magnetic semiconductor

    International Nuclear Information System (INIS)

    Talati, Mina; Shinde, Satyam; Jha, Prafulla K.

    2004-01-01

    The present work employs interionic potential approach based on charge transfer effect to calculate and describe the high pressure phase transition and elastic behaviour of the diluted magnetic semiconductors Zn 1-x M x Se (M=Cd, Fe and Mn). We have obtained a reasonably good agreement between present calculated values and experimentally observed data on the phase transition pressures. The volume collapses and high pressure behaviours are also in reasonably good agreement with the available data for all compounds under consideration. The variations of elastic constants and their combinations with pressure follow a systematic trend, identical to that observed in other compounds of zinc blende structure family. The present approach has also succeeded in predicting the Born and relative stability criteria

  8. Manufacturing of ultra-large diameter 20 MnMoNi 5 5 steel forgings for reactor pressure vessels and their properties

    International Nuclear Information System (INIS)

    Onodera, S.; Kawaguchi, S.; Tsukada, H.; Moritani, H.; Suzuki, K.; Sato, I.

    1985-01-01

    As the structural material for RPV typical of increased dimensions, as set of ultra-large diameter steel forgings for a PHWR RPV is presented as outlined below. (1) Material designation: 20 MnMoNi 5 5 (similar to SA508, Cl.3) (2) Size of the forgings: flanges, 8.440 mm OD, a weight of 238 tons for shell flange; shells and torus, 7,920 mm OD, with large height, cover dome, 6,800 mm OD in chord and 460 mm thick; blank before formed to dome is ca. 8,000 mm OD. (3) Chemical composition: particular effort was made for minimizing the tramp elements as P, S, As, Sn, Sb, Cu. (4) Manufacturing, key points: steel making - combined refining and degassing in ladle; ingot making - largest size ingots, including 570 ton and 500 ton ingots; forging - special ''outside-the-press'' forging and forming techniques; heat treatment - prevention of H 2 flaking in normalizing and tempering and handling of the extra-large forgings at water quenching. (5) Metallurgical properties: sufficiently uniform carbon distributions in the forgings; a lowest possible content of hydrogen, non-metallic inclusions and oxygen. Mechanical properties: uniformity in tensile and toughness properties; flaws - only limited number of spots of UT indications under 2 mm EFG (EFS). (orig.)

  9. Investigation of the optical properties of MoS2 thin films using spectroscopic ellipsometry

    International Nuclear Information System (INIS)

    Yim, Chanyoung; O'Brien, Maria; Winters, Sinéad; McEvoy, Niall; Mirza, Inam; Lunney, James G.; Duesberg, Georg S.

    2014-01-01

    Spectroscopic ellipsometry (SE) characterization of layered transition metal dichalcogenide (TMD) thin films grown by vapor phase sulfurization is reported. By developing an optical dispersion model, the extinction coefficient and refractive index, as well as the thickness of molybdenum disulfide (MoS 2 ) films, were extracted. In addition, the optical band gap was obtained from SE and showed a clear dependence on the MoS 2 film thickness, with thinner films having a larger band gap energy. These results are consistent with theory and observations made on MoS 2 flakes prepared by exfoliation, showing the viability of vapor phase derived TMDs for optical applications

  10. Diffusion barrier performances of thin Mo, Mo-N and Mo/Mo-N films between Cu and Si

    International Nuclear Information System (INIS)

    Song Shuangxi; Liu Yuzhang; Mao Dali; Ling Huiqin; Li Ming

    2005-01-01

    In this work, we have studied the diffusion barrier performances of Mo, Mo-N and Mo/Mo-N metallization layers deposited by sputtering Mo in Ar/N 2 atmospheres, respectively. Samples were subsequently annealed at different temperatures ranging from 400 to 800 deg C in vacuum condition. The film properties and their suitability as diffusion barriers and protective coatings in silicon devices were characterized using four-point probe measurement, X-ray diffractometry, scanning electron microscopy, Auger electron spectroscopy and transmission electron microscopy analyses. Experimental results revealed that the Mo (20 nm)/Mo-N (30 nm) layer was able to prevent the diffusion reaction between Cu and Si substrate after being annealed at 600 deg C for 30 min. The adhesion between layers and the content of N atoms are the key parameters to improve the properties of Mo-based barrier materials. The Mo layer interposed between Cu and Mo-N diluted the high nitrogen concentration of the barrier and so enhanced the barrier performances

  11. NMR and XAS Study of Fe-Mo Double Perovskites

    International Nuclear Information System (INIS)

    Zajac, D.A.; Kapusta, C.; Borowiec, M.; Sikora, M.; Marquina, C.; Blasco, J.; Ibarra, M.R.

    2005-01-01

    The results of NMR and XAS measurements of the A 2 FeMoO 6 double perovskites (DP) (A 2 =Sr 2 , SrBa, Ba 2 , Ca 2 ) at the Fe and Mo K edges are reported and the information on the individual site electronic and magnetic properties is analysed. The compounds studied belong to the family of materials exhibiting a high field '' colossal '' magnetoresistance as well as a low field '' giant '' magnetoresistance. Magnetoresistive properties of the compounds arise from their half-metallicity, i.e. only one spin direction being populated in the conduction band, which consists of overlapping spin down 3d Fe, 2p O and 4d Mo electron bands. Within the model, a spin-down electron undergoes a fast hopping through unoccupied oxygen 2p orbitals between Fe 3+ (3d 5 - spin up) and Mo 6+ (4d 0 ) ionic cores. This mechanism implicates an anti-parallel coupling of the Fe and Mo spins and leads to non-integer magnetic moments and a metallic character below TC. The interaction, in analogy with the '' double exchange '' (DE) in manganites, is called '' double exchange-like '' interaction. The superexchange interaction (SE) is also expected to be present, resulting also in an anti-parallel coupling of 3d Fe 3+ and 4d Mo 5+ spins through occupied oxygen 2p orbitals. The insulating character of SE is connected with an increase of the tilt angle of the Fe-O-Mo bond, which is related to a change of the structural tolerance factor f and results in structural distortions. The molybdenum NMR measurements revealed the existence of a non-integer magnetic moment at Mo and Fe, which can be attributed to the DE-like interaction. However, experiments using Moessbauer spectroscopy have shown the existence of two Fe ionisation states - with integer (SE) and non integer (DE) magnetic moments. The 95 Mo and 97 Mo NMR measurements on A 2 FeMoO 6 (A 2 =Sr 2 , SrBa, Ba 2 , Ca 2 ) presented in this work show different values of the Mo hyperfine field and the corresponding magnetic moment. This is attributed

  12. Nanostructured Mo-based electrode materials for electrochemical energy storage.

    Science.gov (United States)

    Hu, Xianluo; Zhang, Wei; Liu, Xiaoxiao; Mei, Yueni; Huang, Yunhui

    2015-04-21

    The development of advanced energy storage devices is at the forefront of research geared towards a sustainable future. Nanostructured materials are advantageous in offering huge surface to volume ratios, favorable transport features, and attractive physicochemical properties. They have been extensively explored in various fields of energy storage and conversion. This review is focused largely on the recent progress in nanostructured Mo-based electrode materials including molybdenum oxides (MoO(x), 2 ≤ x ≤ 3), dichalconides (MoX2, X = S, Se), and oxysalts for rechargeable lithium/sodium-ion batteries, Mg batteries, and supercapacitors. Mo-based compounds including MoO2, MoO3, MoO(3-y) (0 energy storage systems because of their unique physicochemical properties, such as conductivity, mechanical and thermal stability, and cyclability. In this review, we aim to provide a systematic summary of the synthesis, modification, and electrochemical performance of nanostructured Mo-based compounds, as well as their energy storage applications in lithium/sodium-ion batteries, Mg batteries, and pseudocapacitors. The relationship between nanoarchitectures and electrochemical performances as well as the related charge-storage mechanism is discussed. Moreover, remarks on the challenges and perspectives of Mo-containing compounds for further development in electrochemical energy storage applications are proposed. This review sheds light on the sustainable development of advanced rechargeable batteries and supercapacitors with nanostructured Mo-based electrode materials.

  13. High temperature strength and aging behavior of 12%Cr-15%Mn austenitic steels

    International Nuclear Information System (INIS)

    Miyahara, Kazuya; Bae, Dong-Su; Sakai, Hidenori; Hosoi, Yuzo

    1993-01-01

    High Mn-Cr austenitic steels are still considered to be an important high temperature structural material from the point of view of reduced radio-activation. The objective of the present study is to make a fundamental research of mechanical properties and microstructure of 12%Cr-15%Mn austenitic steels. Especially the effects of alloying elements of V and Ti on the mechanical properties and microstructure evolution of high Mn-Cr steels were studied. Precipitation behaviors of carbides, nitrides and σ phase are investigated and their remarkable effects on the high temperature strength are found. The addition of V was very effective for strengthening the materials with the precipitation of fine VN. Ti was also found to be beneficial for the improvement of high temperature strength properties. The results of high temperature strengths of the 12Cr-15Mn austenitic steels were compared with those of the other candidate and/or reference materials, for example, JFMS (modified 9Cr-2Mo ferritic stainless steel) and JPCAs (modified 316 austenitic stainless steels). (author)

  14. Crystalline structure and electrical properties of solid solutions YNixMn1-xO3

    Directory of Open Access Journals (Sweden)

    Moure, C.

    1999-12-01

    Full Text Available Solid solutions belonging to the Mn-rich region of the YNiXMn1-XO3 system have been studied. The powders were prepared by solid state reaction between the corresponding oxides. Sintered ceramics were obtained by firing at 1325-1350ºC. The incorporation of 20 atomic % Ni2+ to the Yttrium manganite induces the formation of a perovskite phase, with orthorhombic symmetry. Increase of the Ni amount leads to an increase of the orthorhombicity factor b/a, up to an amount of 50 atomic % Ni2+. Above this Ni amount, a biphasic system has been observed, with the presence of unreacted Y2O3. DC electrical conductivity measurements have shown semiconducting behaviour for all the solid solutions with perovskite-type structure. The room temperature conductivity increases with Ni until ~33 atomic % Ni, and then decreases. The 50/50 Ni/Mn composition has different values of conductivity and activation energy against those corresponding to samples with lower values of that ionic ratio. Small polaron hopping mechanism controls the conductivity in these ceramics. Results are discussed as a function of the Mn3+/Mn4+ ratio for each composition.Se han estudiado las soluciones sólidas correspondientes a la región rica en Mn del sistema YNiXMn1-XO3, entre 0 y 50 atomic % Ni. Los compuestos fueron preparados por reacción en estado sólido de los óxidos correspondientes. Se sinterizaron materiales cerámicos a 1325-1350ºC. Con cantidades de 20 atomic % Ni se produce la formación de una fase con estructura de perovskita, y simetría ortorrómbica. La distorsión ortorrómbica crece con el contenido de Ni. Por encima de 50 atomic % Ni, aparece Y2O3 sin reaccionar. Las soluciones sólidas muestran semiconducción con valores de σ que aumentan con el contenido de Ni hasta ~33 atomic %, para luego decrecer, hasta x=0.5. La composición 50/50 Ni/Mn muestra un comportamiento eléctrico algo diferente. Se discuten los resultados en función de la razón Mn3+/Mn4+ para cada

  15. Magnetic properties of Fe-rich rare-earth intermetallic compounds with a ThMn12 structure

    International Nuclear Information System (INIS)

    Ohashi, K.; Tawara, Y.; Osugi, R.; Shimao, M.

    1988-01-01

    Sm(Fe/sub 1-//sub x/M/sub x/) 12 ternary compounds based on the tetragonal ThMn 12 structure where M is Ti, Si, V, Cr, and Mo were investigated. M atoms have a preference for site occupation. Ti atoms occupy the 8i or 8j site and Cr atoms occupy the 8i site. Curie temperatures on Sm(M,Fe) 12 compounds are around 590 K except for the SmMo 2 Fe 10 compound (T/sub c/ = 483 K). The SmTiFe 11 and SmSi 2 Fe 10 compounds have a high saturation magnetization and magnetic anisotropy

  16. Investigation of the optical properties of MoS{sub 2} thin films using spectroscopic ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Yim, Chanyoung; O' Brien, Maria; Winters, Sinéad [School of Chemistry, Trinity College Dublin, Dublin 2 (Ireland); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); McEvoy, Niall [Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); Mirza, Inam; Lunney, James G. [Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Duesberg, Georg S., E-mail: duesberg@tcd.ie [School of Chemistry, Trinity College Dublin, Dublin 2 (Ireland); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); Advanced Materials and BioEngineering Research (AMBER) Centre, Trinity College Dublin, Dublin 2 (Ireland)

    2014-03-10

    Spectroscopic ellipsometry (SE) characterization of layered transition metal dichalcogenide (TMD) thin films grown by vapor phase sulfurization is reported. By developing an optical dispersion model, the extinction coefficient and refractive index, as well as the thickness of molybdenum disulfide (MoS{sub 2}) films, were extracted. In addition, the optical band gap was obtained from SE and showed a clear dependence on the MoS{sub 2} film thickness, with thinner films having a larger band gap energy. These results are consistent with theory and observations made on MoS{sub 2} flakes prepared by exfoliation, showing the viability of vapor phase derived TMDs for optical applications.

  17. Microstructure and properties of MoSi2-MoB and MoSi2-Mo5Si3 molybdenum silicides

    International Nuclear Information System (INIS)

    Schneibel, J.H.; Sekhar, J.A.

    2003-01-01

    MoSi 2 -based intermetallics containing different volume fractions of MoB or Mo 5 Si 3 were fabricated by hot-pressing MoSi 2 , MoB, and Mo 5 Si 3 powders in vacuum. Both classes of alloys contained approximately 5 vol.% of dispersed silica phase. Additions of MoB or Mo 5 Si 3 caused the average grain size to decrease. The decrease in the grain size was typically accompanied by an increase in flexure strength, a decrease in the room temperature fracture toughness, and a decrease in the hot strength (compressive creep strength) measured around 1200 deg. C, except when the Mo 5 Si 3 effectively became the major phase. Oxidation measurements on the two classes of alloys were carried out in air. Both classes of alloys were protected from oxidation by an in-situ adherent scale that formed on exposure to high temperature. The scale, although not analyzed in detail, is commonly recognized in MoSi 2 containing materials as consisting mostly of SiO 2 . The MoB containing materials showed an increase in the scale thickness and the cyclic oxidation rate at 1400 deg. C when compared with pure MoSi 2 . However, in contrast with the pure MoSi 2 material, oxidation at 1400 deg. C began with a weight loss followed by a weight gain and the formation of the protective silica layer. The Mo 5 Si 3 containing materials experienced substantial initial weight losses followed by regions of small weight changes. Overall, the MoB and Mo 5 Si 3 additions to MoSi 2 tended to be detrimental for the mechanical and oxidative properties

  18. The crystal chemistry of novel thorium and uranium compounds with oxo-anions from group VI of periodic table (S, Se, Te, Cr, Mo and W)

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Bin

    2016-01-26

    This dissertation focus on the synthesis, phase studies and physicochemical properties of novel thorium and uranium compounds with the Group VI (S, Se, Te, Cr, Mo, W) of the Periodic Table. All the studied compounds are listed in Table 2.2 from the page 15. I subdivided all the newly synthesized compounds into several chapters according to their structural and topological differences. First, for thorium molybdates and tungstates, almost all of these compounds are based on corner-sharing of ThO{sub x} (x = 6, 8 and 9) and MoO{sub 4} or WO{sub x} (x = 4, 5, 6) polyhedra. Interestingly, all these compounds can be seen as derived from a pure thorium molybdate compound (ThMo{sub 2}O{sub 8}) which was isolated from high-temperature solid-state synthesis method. Therefore, the polymorphs of this most basic ThMo{sub 2}O{sub 8} compound is firstly introduced (see Chapter 3.1 from page 18). The thermodynamic, electronic and vibrational properties of all investigated ThMo{sub 2}O{sub 8} polymorphs were studied using ab initio calculations. Then, two subfamilies of thorium molybdates, that is, rubidium thorium molybdate and cesium thorium molybdate and their thermal and vibrational behaviors were discussed in details in Chapter 4.1 from page 37 and Chapter 4.2 from page 50, respectively. Moreover, some new insights about the complexity of thorium tungstates were also discussed (Chapter 4.3 from page 59). Some novel thorium molybdate and chromate compounds synthesized from aqueous condition are discussed in Chapter 5 from page 71. In the Chapter 8.2.4, the stereochemistry for thorium and uranium compounds are introduced, especially thorium selinites and uranyl tellurites (see Chapter 6.1 from page 82), thorium tellurites (Chapter 6.2 from page 93), and uranyl tellurites (Chapter 6.3 from page 99 for sodium uranyl tellurium and Chapter 6.4 from page 110 for potassium uranyl tellurium, respectively). In the actinide tellurium systems, additional MoO{sub 3}/WO{sub 3} were also

  19. How the sedimentary Re/Mo ratio and Tl enrichments trace past and present opaline productivity

    Science.gov (United States)

    Böning, Philipp; Brumsack, Hans-Jürgen

    2010-05-01

    preconcentration step for Mo on particles to explain the very low Re/Mo ratios, while Re only seems to accumulate via diffusion. However, our data suggest that the carrier phases are not Mn-oxides but fresh biogenic detritus. Further, since Mo and Cd are well correlated (Böning et al., 2004) our findings suggest a similar, biodetrital source for both elements. This would imply a non-conservative behaviour of Mo, which corroborates findings where dissolved Mo becomes depleted in coastal and open-ocean waters and consequently enriched on biogenic particles after algal blooms (Tuit and Ravizza, 2003; Dellwig et al. 2007). Concerning Tl, it is yet to be determined wether this element is directly associated with the opaline hard parts or the related fresh organic matter. However, the implied particle reactivity of Tl suggests a non-conservative behaviour of this element. Further, our data do not support an involvement of Tl with Mn but rather an association with biological cycling. References: Böning, P. et al. (2009) Mar. Geol. 259, 112-121; Böning, P. et al. (2004) Geochim. Cosmochim. Acta 68, 4429-4451; Crusius, J. et al. (1996) Earth Plan. Sci. Lett. 145, 65-78; Dellwig, O. et al. (2007) Geochim. Cosmochim. Acta 71, 2745-2761; Tuit, C. and Ravizza, G. (2003) Geochim. Cosmochim. Acta 67, A495, Suppl. 1; Wolf, A. (2002) Dissertation, University of Kiel, Germany, pp. 88.

  20. Investigation into the dehydration of selenate doped Na2M(SO4)2·2H2O (M = Mn, Fe, Co and Ni): Stabilisation of the high Na content alluaudite phases Na3M1.5(SO4)3-1.5x(SeO4)1.5x (M = Mn, Co and Ni) through selenate incorporation

    Science.gov (United States)

    Driscoll, L. L.; Kendrick, E.; Knight, K. S.; Wright, A. J.; Slater, P. R.

    2018-02-01

    In this paper we report an investigation into the phases formed on dehydration of Na2M(SO4)2-x(SeO4)x·2H2O (0 ≤ x ≤ 1; M = Mn, Fe, Co and Ni). For the Fe series, all attempts to dehydrate the samples doped with selenate resulted in amorphous products, and it is suspected that a side redox reaction involving the Fe and selenate may be occurring leading to phase decomposition and hence the lack of a crystalline product on dehydration. For M = Mn, Co, Ni, the structure observed was shown to depend upon the transition metal cation and level of selenate doping. An alluaudite phase, Na3M1.5(SO4)3-1.5x(SeO4)1.5x, was observed for the selenate doped compositions, with this phase forming as a single phase for x ≥ 0.5 M = Co, and x = 1.0 M = Ni. For M = Mn, the alluaudite structure is obtained across the series, albeit with small impurities for lower selenate content samples. Although the alluaudite-type phases Na2+2y(Mn/Co)2-y(SO4)3 have recently been reported [1,2], doping with selenate appears to increase the maximum sodium content within the structure. Moreover, the selenate doped Ni based samples reported here are the first examples of a Ni sulfate/selenate containing system exhibiting the alluaudite structure.

  1. Effect of conventional and subzero treating on the mechanical properties of aged martensitic Fe-12 wt.% Ni-X wt.% Mn alloys

    International Nuclear Information System (INIS)

    Nedjad, S. Hossein; Nili-Ahmadabadi, M.; Mahmudi, R.; Farhangi, H.

    2003-01-01

    Fe-Ni-Mn maraging alloys are suffering from sever embrittlement after aging. Mechanism of the embrittelement has not been well understood yet. Segregation of Mn atoms or formation of Austenite particles at prior Austenite grain boundaries (PAGBs) have been reported as embrittelement mechanisms while it remains controversial now. For better understanding of embrittelement behavior, effect of subzero treating after aging, double aging and modification of alloy composition on the mechanical properties and fracture behavior were investigated. Alloys of chemical compositions Fe-11.9 wt.% Ni-6.3 wt.% Mn and Fe-10.5 wt.% Ni-5.8 wt.% Mo-3 wt.% Mn were studied. Double solution annealing was performed at 1223 and 1093 K for 3.6 ks followed by water quenching. After aging at 723 K for 0.9 ks (under aging) and 172.8 ks (over aging), tensile properties of specimens heat treated conventionally and cryogenically were measured. Double aging was done at 623 K for 3.6 ks followed by a step aging at 753, 783 and 803 K. Aging behavior and tensile properties of Fe-10.5 wt.% Ni-5.8 wt.% Mo-3 wt.% Mn were investigated after aging at 773 K. Results showed that alloy modification yields reasonable tensile properties while subzero treatment and double aging couldn't improve tensile properties. An insight toward more investigation of the embrittelement mechanism was made on the basis of this study

  2. Trace- and rare-earth element geochemistry and Pb-Pb dating of black shales and intercalated Ni-Mo-PGE-Au sulfide ores in Lower Cambrian strata, Yangtze Platform, South China

    Science.gov (United States)

    Jiang, Shao-Yong; Chen, Yong-Quan; Ling, Hong-Fei; Yang, Jing-Hong; Feng, Hong-Zhen; Ni, Pei

    2006-08-01

    The Lower Cambrian black shale sequence of the Niutitang Formation in the Yangtze Platform, South China, hosts an extreme metal-enriched sulfide ore bed that shows >10,000 times enrichment in Mo, Ni, Se, Re, Os, As, Hg, and Sb and >1,000 times enrichment in Ag, Au, Pt, and Pd, when compared to average upper continental crust. We report in this paper trace- and rare-earth-element concentrations and Pb-Pb isotope dating for the Ni-Mo-PGE-Au sulfide ores and their host black shales. Both the sulfide ores and their host black shales show similar trace-element distribution patterns with pronounced depletion in Th, Nb, Hf, Zr, and Ti, and extreme enrichment in U, Ni, Mo, and V compared to average upper crust. The high-field-strength elements, such as Zr, Hf, Nb, Ta, Sc, Th, rare-earth elements, Rb, and Ga, show significant inter-element correlations and may have been derived mainly from terrigenous sources. The redox sensitive elements, such as V, Ni, Mo, U, and Mn; base metals, such as Cu, Zn, and Pb; and Sr and Ba may have been derived from mixing of seawater and venting hydrothermal sources. The chondrite-normalized REE patterns, positive Eu and Y anomalies, and high Y/Ho ratios for the Ni-Mo-PGE-Au sulfide ores are also suggestive for their submarine hydrothermal-exhalative origin. A stepwise acid-leaching Pb-Pb isotope analytical technique has been employed for the Niutitang black shales and the Ni-Mo-PGE-Au sulfide ores, and two Pb-Pb isochron ages have been obtained for the black shales (531±24 Ma) and for the Ni-Mo-PGE-Au sulfide ores (521±54 Ma), respectively, which are identical and overlap within uncertainty, and are in good agreement with previously obtained ages for presumed age-equivalent strata.

  3. Luminescence of MnS in glasses: spectroscopic probe for the study of thermal phase separation

    Energy Technology Data Exchange (ETDEWEB)

    Menassa, P E

    1984-01-01

    A new approach for studying thermal phase separation in sodium borosilicate glasses using MnS as a luminescent probe is investigated. Seventy-one samples of glasses activated by MnS inside and around the Na2O.B2O3.SiO2 miscibility gaps were prepared. These samples were then phase separated by dry thermal treatment. It is shown that on addition of MnO, the ternary Na2O.B2O3.SiO2 system behaved like other quaternary systems of the type X2O.MO.B2O3.SiO2 (X = Na, K; M = Mg, Ca, Ba, Zn). Scanning electron microscopy and X-ray microanalysis demonstrated that manganese concentrates preferentially in the boron-rich phase. This, analysis, in conjuction with a comparison of MnS emission spectra of upheated and heat treated glasses shows that the glasses are submicroscopically phase separated when prepared. The decay-time analysis of MnS luminescence indicates that the low energy emission band arises from MnS in the boron-rich phase while the high energy emission is due to MnS in the silica-rich phase. The difference in the crystal field parameters obtained from the excitation spectra of the two emission bands shows that the high energy emission band is from MnS in tetrahedral sites while the low energy emission band is from MnS in an octahedral environment.

  4. Production of hydrogen with methane decomposition using Ni-Mn/Ce-ZrO{sub 2} catalysts; Produccion de hidrogeno via descomposicion de metano mediante catalizadores de Ni-Mn/Ce-ZrO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, C; Hernandez-Pichardo, M L; Valenzuela, M A [Instituto Politecnico Nacional-ESIQIE, Mexico, D.F. (Mexico); Del Angel, P; Montoya de la Fuente, J.A. [Instituto Mexicano del Petroleo, Mexico, D.F. (Mexico)

    2009-09-15

    The catalytic decomposition of methane makes it possible to obtain CO and CO{sub 2} free hydrogen, which is a desirable characteristic for fuel cell applications. In addition, this method simultaneously obtains diverse carbon nanostructures with a large variety of applications. This work prepared catalysts with different Ni contents supported by Ce-Zr mixed oxides and doped with manganese to promote activity. The supports were synthesized with surfactant-assisted coprecipitation. The Ni and Mn deposits were performed using conventional impregnation for evaluation in the methane decomposition catalyst at 500 degrees Celsius. It was observed that with the incorporation of 1% of Mn into the Ni0 active phase, the conversion of methane into hydrogen and carbon nanostructures increased. The results of reduction at the programmed temperature indicate that the addition of Mn enables the formation of different NiO{sub x} species, increasing dispersion and the degree of reduction to Ni0. Analyses with electron and transmission microscopy show the formation of distinct species of carbon, including nanotubes, nanofibers and concentric onion-like structures, as well as a significant formation of encapsulated Ni0 particles. [Spanish] La descomposicion catalitica de metano permite la obtencion de hidrogeno libre de CO y CO{sub 2}, lo cual es una caracteristica deseable para su aplicacion en celdas de combustible. Ademas, por esta ruta, simultaneamente se obtienen diversas nanoestructuras de carbono con una gran variedad de aplicaciones. En este trabajo se prepararon catalizadores con diferentes contenidos de Ni soportados en oxidos mixtos Ce-Zr y se doparon con manganeso como promotor de actividad. Los soportes se sintetizaron por coprecipitacion asistida por surfactante y el deposito del Ni y del Mn se efectuo por impregnacion convencional para su evaluacion en la descomposicion catalitica de metano a 500 grados centigrados. Se observo que mediante la incorporacion de 1% de Mn a

  5. Ultrathin ZnSe nanowires: one-pot synthesis via a heat-triggered precursor slow releasing route, controllable Mn doping and application in UV and near-visible light detection.

    Science.gov (United States)

    Li, Dong; Xing, Guanjie; Tang, Shilin; Li, Xiaohong; Fan, Louzhen; Li, Yunchao

    2017-10-12

    We report herein a heat-triggered precursor slow releasing route for the one-pot synthesis of ultrathin ZnSe nanowires (NWs), which relies on the gradual dissolving of Se powder into oleylamine containing a soluble Zn precursor under heating. This route allows the reaction system to maintain a high monomer concentration throughout the entire reaction process, thus enabling the generation of ZnSe NWs with diameter down to 2.1 nm and length approaching 400 nm. The size-dependent optical properties and band-edge energy levels of the ZnSe NWs were then explored in depth by UV-visible spectroscopy and cyclic voltammetry, respectively. Considering their unique absorption properties, these NWs were specially utilized for fabricating photoelectrochemical-type photodetectors (PDs). Impressively, the PDs based on the ZnSe NWs with diameters of 2.1 and 4.5 nm exhibited excellent responses to UVA and near-visible light, respectively: both possessed ultrahigh on/off ratios (5150 for UVA and 4213 for near-visible light) and ultrawide linear response ranges (from 2.0 to 9000 μW cm -2 for UVA and 5.0 to 8000 μW cm -2 for near-visible light). Furthermore, these ZnSe NWs were selectively doped with various amounts of Mn 2+ to tune their emission properties. As a result, ZnSe NW film-based photochromic cards were creatively developed for visually detecting UVA and near-visible radiation.

  6. Correlation between the nanocrystalline Sm(Fe,Mo){sub 12} and its out of equilibrium phase Sm(Fe,Mo){sub 10}

    Energy Technology Data Exchange (ETDEWEB)

    Khazzan, S. [CMTR, ICMPE, UMR7182, CNRS - Université Paris Est, 2-8 rue Henri Dunant, F-94320 Thiais (France); Laboratoire Matériaux Organisation et Propriétés, Faculté des Sciences de Tunis, Université de Tunis El Manar, 2092 Tunis (Tunisia); Bessais, L., E-mail: bessais@glvt.cnrs.fr [CMTR, ICMPE, UMR7182, CNRS - Université Paris Est, 2-8 rue Henri Dunant, F-94320 Thiais (France); Van Tendeloo, G. [EMAT, University of Antwerp, B-2020 Antwerp (Belgium); Mliki, N. [Laboratoire Matériaux Organisation et Propriétés, Faculté des Sciences de Tunis, Université de Tunis El Manar, 2092 Tunis (Tunisia)

    2014-08-01

    Nanostructured Sm–Fe–Mo semi-hard magnetic material exhibiting enhanced magnetic properties can be produced by ball milling followed by recrystallization. Milled samples were annealed for 30 min in a vacuum at different temperatures (T{sub A}) between 700 and 1190 °C. The effects of heat treatment and Mo content on structural and magnetic property changes have been investigated by means of X-ray diffraction using the Rietveld method, transmission electron microscopy and magnetic measurements. For samples annealed at T{sub A}>900°C the tetragonal ThMn{sub 12}-type structure is identified, while for 700Mo{sub x}){sub 10}, correlated with structural transformation towards its equilibrium derivative I4/mmm Sm(Fe{sub 1−x}Mo{sub x}){sub 12}. A maximum of the coercive field H{sub C} (H{sub C}>5kOe) has been observed for the new hexagonal P6/mmm phase suggesting that nanocrystalline Sm(Fe,Mo){sub 10}, is a semi-hard material, and is potential candidate for magnetic recording. - Highlights: • A study of the structure and magnetic properties of SmFeMo compound. • A new out of equilibrium P6/mmm-type structure was found. • Correlation between the 1/12 phase and its out of equilibrium 1/10 phase.

  7. SE PREVENINDO?

    Directory of Open Access Journals (Sweden)

    Ana Débora Assis Moura

    2010-01-01

    Full Text Available Este estudio tuvo como objetivo verificar el comportamiento de las prostitutas en relación a la prevención de enfermedades de transmisión sexual y del Síndrome de Inmunodeficiencia Adquirida-SIDA, así como investigar cómo se previenen de esas enfermedades. Se trata de una investigación exploratoria, con enfoque cualitativo, llevada a cabo en la Asociación de las Prostitutas en Ceará, Brazil, en septiembre de 2008, a través de una encuesta con 25 prostitutas. El análisis de los datos se hizo según el análisis de contenido, después de ser agrupados en cuatro categorías: conocimiento sobre las enfermedades de transmisión sexual/SIDA; convivencia con la(s enfermedad(es; prevención de la enfermedad de transmisión sexual/SIDA; y el uso de drogas. Se concluyó que las prostitutas no usan preservativos en todas las relaciones sexuales, por lo tanto, las enfermedades de transmisión sexual representan una realidad; la desinformación sobre la(s enfermedad(es es notable; el consumo de drogas lícitas e ilícitas es frecuente entre ellas, factor que las expone a situaciones más vulnerables con relación al VIH/SIDA.

  8. Fabrication of a Cu(InGaSe2 Thin Film Photovoltaic Absorber by Rapid Thermal Annealing of CuGa/In Precursors Coated with a Se Layer

    Directory of Open Access Journals (Sweden)

    Chun-Yao Hsu

    2013-01-01

    Full Text Available Cu(InGaSe2 (CIGS thin film absorbers are prepared using sputtering and selenization processes. The CuGa/In precursors are selenized during rapid thermal annealing (RTA, by the deposition of a Se layer on them. This work investigates the effect of the Cu content in precursors on the structural and electrical properties of the absorber. Using X-ray diffraction, field emission scanning electron microscopy, Raman spectroscopy, and Hall effect measurement, it is found that the CIGS thin films produced exhibit facetted grains and a single chalcopyrite phase with a preferred orientation along the (1 1 2 plane. A Cu-poor precursor with a Cu/( ratio of 0.75 demonstrates a higher resistance, due to an increase in the grain boundary scattering and a reduced carrier lifetime. A Cu-rich precursor with a Cu/( ratio of 1.15 exhibits an inappropriate second phase ( in the absorber. However, the precursor with a Cu/( ratio of 0.95 exhibits larger grains and lower resistance, which is suitable for its application to solar cells. The deposition of this precursor on Mo-coated soda lime glass substrate and further RTA causes the formation of a MoSe2 layer at the interface of the Mo and CIGS.

  9. ¿Cómo seducir a un turista?

    Directory of Open Access Journals (Sweden)

    Luis Eladio Proaño

    2015-01-01

    Full Text Available Los profesionales del markenting destacan la importancia de conocer a fondo todo lo que concierne al cliente potencial. Para ellos es indispensable investigar sus valores culturales, sus posibilidades económicas y hábitos de consumo, y hasta sus fantasías íntimas. El objetivo de este artículo es explicar cómo se elabora un plan estratégico de mercadeo, para ello se vale de un plan presentado en Quito, (1991 para promover en los Estados Unidos.

  10. 99Mo production by 100Mo(n,2n)99Mo using accelerator neutrons

    International Nuclear Information System (INIS)

    Sato, Nozomi; Kawabata, Masako; Nagai, Yasuki; Hashimoto, Kazuyuki; Hatsukawa, Yuichi; Saeki, Hideya; Motoishi, Shoji; Kin, Tadahiro; Konno, Chikara; Ochiai, Kentaro; Takakura, Kosuke; Minato, Futoshi; Iwamoto, Osamu; Iwamoto, Nobuyuki; Hashimoto, Shintaro

    2013-01-01

    We proposed a new route to produce a medical radioisotope 99 Mo by the 100 Mo(n,2n) 99 Mo reaction using accelerator neutrons. A high-quality 99 Mo with a minimum level of radioactive waste can be obtained by the proposed reaction. The decay product of 99 Mo, 99m Tc, is separated from 99 Mo by the sublimation method. The proposed route could bring a major breakthrough in the solution of ensuring a constant and reliable supply of 99 Mo. (author)

  11. Two-dimensional square ternary Cu2MX4 (M = Mo, W; X = S, Se) monolayers and nanoribbons predicted from density functional theory

    KAUST Repository

    Gan, Liyong

    2014-03-19

    Two-dimensional (2D) materials often adopt a hexagonal lattice. We report on a class of 2D materials, Cu2MX4 (M = Mo, W; X = S, Se), that has a square lattice. Up to three monolayers, the systems are kinetically stable. All of them are semiconductors with band gaps from 2.03 to 2.48 eV. Specifically, the states giving rise to the valence band maximum are confined to the Cu and X atoms, while those giving rise to the conduction band minimum are confined to the M atoms, suggesting that spontaneous charge separation occurs. The semiconductive nature makes the materials promising for transistors, optoelectronics, and solar energy conversion. Moreover, the ferromagnetism on the edges of square Cu2MX4 nanoribbons opens applications in spintronics.

  12. Two-dimensional square ternary Cu2MX4 (M = Mo, W; X = S, Se) monolayers and nanoribbons predicted from density functional theory

    KAUST Repository

    Gan, Liyong; Schwingenschlö gl, Udo

    2014-01-01

    Two-dimensional (2D) materials often adopt a hexagonal lattice. We report on a class of 2D materials, Cu2MX4 (M = Mo, W; X = S, Se), that has a square lattice. Up to three monolayers, the systems are kinetically stable. All of them are semiconductors with band gaps from 2.03 to 2.48 eV. Specifically, the states giving rise to the valence band maximum are confined to the Cu and X atoms, while those giving rise to the conduction band minimum are confined to the M atoms, suggesting that spontaneous charge separation occurs. The semiconductive nature makes the materials promising for transistors, optoelectronics, and solar energy conversion. Moreover, the ferromagnetism on the edges of square Cu2MX4 nanoribbons opens applications in spintronics.

  13. Comparative study of creep behaviour in three Cr Ni 15/15 steel stabilized with Ti and with different contents in W, Mn, Mo and Bor

    International Nuclear Information System (INIS)

    Solano, R.R.; Rivas, M. de las; Schirra, M.; Seith, B.

    1975-01-01

    The main difference between the three steels which are tested at temperature range from 650 0 C to 750 0 C is due to the hardening elements pf the matrix and the Boron content: 1. 12R72HV (X10NiCrMoTiB 1515) 2% Mn 1,5% Mo 80 ppmB 2. Vaccutherm (X12CrNiWTi 1613) 3% W 2,5 ppmB 3. RGT 21 (X12CrNiWTi 1613) 3% W 50 ppm B. The investigations of all casts are carried out in two different heat treatments which are suitable for the conditions required for the operation of the reactor. Cond. I: 1150 0 C 30 min, water quenced; 800 0 32 hour, air; 10% cold work. Cond. II: 1150 0 C 30 min, water quenched; 10% cold work. In connection with creep test the condition I irrespective of 3 steels show no remarkable difference. The observation at 750 0 C test temperature and also at condition II above 650 0 C on Boron-free Vaccutherm cast shows an unfavourable behaviour. There is no significant difference in the stress dependence of secondary creep rate and also absolute creep rate. A definite superiority is to be found for 12R72HV when considering the values for time-yield-limit-ratio and ductility compared to the W-steels. The test results shows different fracture behaviour. Transcrystalline fracture is found on cast 12R72HV, whereas RGT 21 and Vaccutherm show transition from transcrystalline to intercrystalline fracture, depending on the rupture time and test temperature. The long term rupture specimens show intercrystalline fracture. (author)

  14. Electrodeposition of Ni-Mo nanoparticles for the electrocatalytic hydrogen evolution reaction; Electrodepositacion de nanoparticulas de Ni-Mo para la electrocatalisis de la reaccion de evolucion de hidrogeno

    Energy Technology Data Exchange (ETDEWEB)

    Videa, M.; Crespo, D.; Casillas, G.; Zavala, G. [Tecnologico de Monterrey Campus Monterrey, Monterrey, Nuevo Leon (Mexico)]. E-mail: mvidea@eitesm.mx

    2009-09-15

    This work reports on the generation of nickel- molybdenum deposits from the application of direct current in an electrolytic bath composed of a basic solution of NiSO{sub 4}, Na{sub 2}MoO{sub 4} and Na{sub 3}C{sub 6}H5O7. The working electrodes used were 1mm diameter vitreous carbon discs and carbon felt. The catalytic activity of the deposits was evaluated with cyclic voltamperometry in a 0.72M solution of H{sub 2}SO{sub 4}. Deposits were generated on the vitreous carbon discs, which showed catalytic activity for the HER. Deposits were obtained with better properties, showing a pulse of 200 mA/cm{sup 2}. The 42 mA/cm{sup 2} pulse experiments with varying durations showed that their catalytic capacities are better than expected, in spite of the use of small quantities of charge obtained with 90 ms and 300s. Low activity was observed in the absence of MoO{sub 4}{sup 2-} in the electrolytic bath during the electrodeposition process, indicating the importance of the presence of Mo to the catalytic activity. The deposits were inspected using atomic force microscopy (AFM). Though the electrodeposition on carbon felt is possible, the experiments were not reproducible because control over the active area of the electrode is difficult to achieve. NiMo nanoparticles on carbon filter fibers can be obtained using pulses with sufficient intensity and duration. [Spanish] En este trabajo se reporta la generacion de depositos de niquel-molibdeno mediante la aplicacion de corriente directa en un bano electrolitico compuesto por una solucion basica de NiSO{sub 4}, Na{sub 2}MoO{sub 4} y Na{sub 3}C{sub 6}H5O7. Se utilizaron como electrodos de trabajo discos de carbon vitreo de 1mm de diametro y fieltro de carbono. La actividad catalitica de los depositos fue evaluada mediante voltamperometria ciclica en una solucion 0.72M de H{sub 2}SO{sub 4}. Sobre los electrodos de carbon vitreo se generaron depositos que mostraron actividad catalitica para la REH. Depositos con mejores propiedades

  15. Sex, age, and tissue specific accumulation of eight metals, arsenic, and selenium in the European hedgehog (Erinaceus europaeus).

    Science.gov (United States)

    Rautio, Anni; Kunnasranta, Mervi; Valtonen, Anu; Ikonen, Mirva; Hyvärinen, Heikki; Holopainen, Ismo J; Kukkonen, Jussi V K

    2010-11-01

    Many insectivores have been shown to be sensitive to heavy metals and therefore suitable for biomonitoring purposes. In Finland, the hibernation period of the European hedgehog (Erinaceus europaeus) is long, and during hibernation the stress caused by environmental toxins may be crucial. Concentrations of cadmium (Cd), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), arsenic (As), and selenium (Se) were measured in a population of hedgehogs in the town of Joensuu in eastern Finland during the summers of 2004 and 2005. The analyzed tissues were kidney, liver, hair, and spine. The sampled hedgehogs (n = 65) were mainly road-killed animals. As expected, the concentrations of heavy metals were low because the hedgehogs were living in a comparatively unpolluted area. Significant increases with age were found in Cd concentrations (kidney, liver, and spine) and some essential elements (Se in spine, kidney, and liver; Mo in kidney and liver; Cu in spine; Fe in liver; and Mn in spine). Age accumulation and correlations between Se and Cd and between Mo and Cd may indicate the protective roles of Se and Mo against Cd toxicity in hedgehogs, in which Cd is already at comparatively low concentrations. Sex had no significant effect on concentrations of the elements studied. In conclusion, age is an important parameter to be taken into account when studying heavy-metal concentrations in hedgehogs and other insectivores.

  16. Mn bioavailability by polarized Caco-2 cells: comparison between Mn gluconate and Mn oxyprolinate

    Directory of Open Access Journals (Sweden)

    Fulgenzi Alessandro

    2011-07-01

    Full Text Available Abstract Background Micronutrient inadequate intake is responsible of pathological deficiencies and there is a need of assessing the effectiveness of metal supplementation, frequently proposed to rebalance poor diets. Manganese (Mn is present in many enzymatic intracellular systems crucial for the regulation of cell metabolism, and is contained in commercially available metal supplements. Methods We compared the effects of two different commercial Mn forms, gluconate (MnGluc and oxyprolinate (MnOxP. For this purpose we used the polarized Caco-2 cells cultured on transwell filters, an established in vitro model of intestinal epithelium. Since micronutrient deficiency may accelerate mitochondrial efficiency, the mitochondrial response of these cells, in the presence of MnGluc and MnOxP, by microscopy methods and by ATP luminescence assay was used. Results In the presence of both MnOxP and MnGluc a sustained mitochondrial activity was shown by mitoTraker labeling (indicative of mitochondrial respiration, but ATP intracellular content remained comparable to untreated cells only in the presence of MnOxP. In addition MnOxP transiently up-regulated the antioxidant enzyme Mn superoxide dismutase more efficiently than MnGluc. Both metal treatments preserved NADH and βNADPH diaphorase oxidative activity, avoided mitochondrial dysfunction, as assessed by the absence of a sustained phosphoERK activation, and were able to maintain cell viability. Conclusions Collectively, our data indicate that MnOxP and MnGluc, and primarily the former, produce a moderate and safe modification of Caco-2 cell metabolism, by activating positive enzymatic mechanisms, thus could contribute to long-term maintenance of cell homeostasis.

  17. Q values of the 76Ge and 100Mo double-beta decays

    International Nuclear Information System (INIS)

    Rahaman, S.; Elomaa, V.-V.; Eronen, T.; Hakala, J.; Jokinen, A.; Julin, J.; Kankainen, A.; Saastamoinen, A.; Suhonen, J.; Weber, C.; Aystoe, J.

    2008-01-01

    Penning trap measurements using mixed beams of 76 Ge- 76 Se and 100 Mo- 100 Ru have been utilized to determine the double-beta decay Q-values of 76 Ge and 100 Mo with uncertainties less than 200 eV. The value for 76 Ge, 2039.04(16) keV is in agreement with the published SMILETRAP value, 2039.006(50) keV. The new value for 100 Mo, 3034.40(17) keV is 30 times more precise than the previous literature value, sufficient for the ongoing neutrinoless double-beta decay searches in 100 Mo. Moreover, the precise Q-value is used to calculate the phase-space integrals and the experimental nuclear matrix element of double-beta decay

  18. Precios de los medicamentos: cómo se establecen y cuáles son sus sistemas de control

    Directory of Open Access Journals (Sweden)

    Joan Rovira Forns

    2015-01-01

    Full Text Available El precio es una de las principales barreras de acceso a los medicamentos. Por ello es importante conocer cómo se forman los precios y qué factores determinan su cuantía y también qué formas de intervención y regulación son las más adecuadas teniendo en cuenta sus efectos, tanto sobre el acceso, como sobre la innovación, la producción local y otros posibles objetivos de la política de medicamentos. El análisis económico ha desarrollado un conjunto de modelos de mercado que permiten explicar el comportamiento de los precios, aunque los mercados reales divergen sustancialmente de los modelos teóricos. La regulación de precios está justificada por los llamados “fallos de mercado”; la regulación de precios basada en el costo de producción, la modalidad de control de precios más tradicional, ha caído en desuso a favor de los sistemas de precios de referencia internacionales y por la fijación del precio basada en el valor.

  19. Preparation of MoB and MoB-MoSi2 composites by combustion synthesis in SHS mode

    International Nuclear Information System (INIS)

    Yeh, C.L.; Hsu, W.S.

    2007-01-01

    Combustion synthesis in the mode of self-propagating high-temperature synthesis (SHS) was carried out in the Mo-B and Mo-B-Si systems for the preparation of molybdenum boride MoB and the composite of MoB-MoSi 2 from elemental powder compacts. Under a preheating temperature above 150 deg. C , the reaction of Mo with boron in the sample compact of Mo:B = 1:1 is characterized by a planar combustion front propagating in a self-sustaining and steady manner. As the preheating temperature or sample compaction density increased, combustion temperature was found to increase and the propagation rate of the combustion front was correspondingly enhanced. Moreover, the XRD analysis provides evidence of yielding nearly single-phase α-MoB from the Mo-B sample at equiatomic stoichiometry. In the synthesis of MoB-MoSi 2 composites, the starting stoichiometry of the Mo-B-Si powder compact was varied so as to produce the final composites containing 20-80 mol% MoB. It was also found the increase of flame-front velocity and combustion temperature with increasing MoB content formed in the composite. The composition analysis by XRD shows excellent conversion from the Mo-B-Si powder compact to the MoB-MoSi 2 composite through the SHS reaction; that is, in addition to a small amount of Mo 5 Si 3 , the as-synthesized composite is composed entirely of MoB and MoSi 2

  20. Análisis de señales EEG para detección de eventos oculares, musculares y cognitivos

    OpenAIRE

    Gómez Figueroa, Leonardo José

    2016-01-01

    En este Trabajo de Fin de Máster se presenta una investigación a fondo de cómo funcionan los dispositivos electroencefalogramas portátiles, cómo el cerebro humano es dividido en zonas para la clasificación de la información obtenida de los electroencefalogramas, qué variaciones son capaces de medir y como se puede tratar esta información para llegar a construir una interfaz cerebro-ordenador. Para ello se estudian los dispositivos EEG portátiles más utilizados en el mercado durante los últ...

  1. Análisis de señales EEG para detección de eventos oculares, musculares y cognitivos

    OpenAIRE

    Gómez Figueroa, Leonardo José

    2017-01-01

    En este Trabajo de Fin de Máster se presenta una investigación a fondo de cómo funcionan los dispositivos electroencefalogramas portátiles, cómo el cerebro humano es dividido en zonas para la clasificación de la información obtenida de los electroencefalogramas, qué variaciones son capaces de medir y como se puede tratar esta información para llegar a construir una interfaz cerebro-ordenador. Para ello se estudian los dispositivos EEG portátiles más utilizados en el mercado durante los últ...

  2. Antiferromagnetism at the YBa2Cu3O7/La2/3Ca1/3MnO3 interface

    International Nuclear Information System (INIS)

    Haberkorn, N.; Guimpel, J.; Sirena, M.; Steren, L.B.; Saldarriaga, W.; Baca, E.; Gomez, M.E.

    2004-01-01

    The magnetic properties of a series of YBa 2 Cu 3 O 7-x /La 2/3 Ca 1/3 MnO 3 (YBCO/LC 1/3 MO) superlattices grown by dc sputtering at high oxygen pressures (3.5 mbar) show the expected ferromagnetic behavior. However, field-cooled hysteresis loops at a low temperatures show the unexpected existence of exchange bias effect associated with the existence of ferromagnetic/antiferromagnetic (AF) interfaces. The blocking temperature (T B ) is found to be thickness dependent and the exchange bias field (H EB ) is found to be inversely proportional to the ferromagnetic layer thickness, as expected. The presence of an AF material is probably associated with interface disorder and Mn valence shift toward Mn 4+

  3. MnDPDP enhancement in rabbit liver after intravenous bolus injection and slow infusion

    International Nuclear Information System (INIS)

    Thorstensen, Oe.; Isberg, B.; Jorulf, H.; Westman, L.; Svahn, U.; Venizelos, N.

    1997-01-01

    Purpose: To investigate the MR-enhancing effect of mangafodipir trisodium (MnDPDP, Teslascan) in the rabbit liver in relation to dose, mode of administration and imaging window. Material and Methods: MnDPDP was administered to 18 rabbits at a dose of 10 μmol/kg or 20 μmol/kg, as a bolus injection or infusion. MR imaging of the liver was performed at different time intervals. Results: Peak liver enhancement was typically observed 10-30 min after administration and the enhancement declined with a half-time of about 5 h. This pattern was observed in all sequences (SE 400/15, FLASH, and SE 132/10), with both doses and with both rates of administration. The peak enhancement was greater, though not significantly so after 20 μmol/kg than after 10 μmol/kg. A higher relative peak signal was observed with SE 132/10 than with FLASH or SE 400/15. (orig./AJ)

  4. Design of ultrathin Pt-Mo-Ni nanowire catalysts for ethanol electrooxidation.

    Science.gov (United States)

    Mao, Junjie; Chen, Wenxing; He, Dongsheng; Wan, Jiawei; Pei, Jiajing; Dong, Juncai; Wang, Yu; An, Pengfei; Jin, Zhao; Xing, Wei; Tang, Haolin; Zhuang, Zhongbin; Liang, Xin; Huang, Yu; Zhou, Gang; Wang, Leyu; Wang, Dingsheng; Li, Yadong

    2017-08-01

    Developing cost-effective, active, and durable electrocatalysts is one of the most important issues for the commercialization of fuel cells. Ultrathin Pt-Mo-Ni nanowires (NWs) with a diameter of ~2.5 nm and lengths of up to several micrometers were synthesized via a H 2 -assisted solution route (HASR). This catalyst was designed on the basis of the following three points: (i) ultrathin NWs with high numbers of surface atoms can increase the atomic efficiency of Pt and thus decrease the catalyst cost; (ii) the incorporation of Ni can isolate Pt atoms on the surface and produce surface defects, leading to high catalytic activity (the unique structure and superior activity were confirmed by spherical aberration-corrected electron microscopy measurements and ethanol oxidation tests, respectively); and (iii) the incorporation of Mo can stabilize both Ni and Pt atoms, leading to high catalytic stability, which was confirmed by experiments and density functional theory calculations. Furthermore, the developed HASR strategy can be extended to synthesize a series of Pt-Mo-M (M = Fe, Co, Mn, Ru, etc.) NWs. These multimetallic NWs would open up new opportunities for practical fuel cell applications.

  5. Synthesis, magnetization and photocatalytic activity of LaFeO{sub 3} and LaFe{sub 0.5}Mn{sub 0.5-x}O{sub 3-{delta}}

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Zhi-Xian, E-mail: zx_wei@126.com [Beijing Institute of Protective Materials and Technology, Beijing 100081 (China); School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Department of Chemistry, Science Institute, North University of China, Taiyuan, Shanxi 030051 (China); Wang, Yan [Department of Chemistry, Chengde Teachers College for Nationalities, Chengde, Hebei 067000 (China); Liu, Ji-Ping, E-mail: liujp@bit.edu.cn [Beijing Institute of Protective Materials and Technology, Beijing 100081 (China); School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Xiao, Cai-Mei; Zeng, Wei-Wei [Department of Chemistry, Science Institute, North University of China, Taiyuan, Shanxi 030051 (China)

    2012-10-15

    Perovskite LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} and LaFeO{sub 3} were synthesized by stearic acid solution combustion method. The obtained powders were characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), Vibrating sample magnetometer (VSM), XPS techniques and UV-vis absorption spectra techniques. The magnetic properties of the LaFeO{sub 3} and LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} were measured, and they were also evaluated for their photocatalytic activity towards the degradation of methyl orange (MO) under the sunlight irradiation. The experimental results show that the catalytic activities of the LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} were much higher than those of LaFeO{sub 3} due to its higher oxygen vacancies, variable valency Mn ions and the strong absorption in visible light. The optimum conditions for photocatalytic degradation MO using LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} were achieved. The ferromagnetism of the LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} could be caused by the Mn{sup 3+}/Fe{sup 3+} and Mn{sup 3+}/Mn{sup 4+}double exchange interaction, Mn{sup 3+}/Mn{sup 3+} superexchange interactions as well as the defective state in LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}}. The LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} is applicable to the magnetic separation process for its lower coercivity (Hc) and remanent magnetization (Mr), and it can be reusable and maintain relatively high activity. -- Highlights: Black-Right-Pointing-Pointer The LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} is a bifunctional photocatalyst. Black-Right-Pointing-Pointer The origin of the ferromagnetism of the LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} is discussed. Black-Right-Pointing-Pointer LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} shows much higher photocatalytic activity than that of LaFeO{sub 3.} Black-Right-Pointing-Pointer LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} can be recycled by an external magnetic

  6. Tumoural portal vein thrombosis. Enhancement with MnDPDP

    International Nuclear Information System (INIS)

    Marti-Bonmati, L.; Lonjedo, E.; Mathieu, D.; Coffin, C.; Poyatos, C.; Anglade, M.C.

    1997-01-01

    Purpose: Intrahepatic thrombus is usually associated with either cirrhosis or hepatocellular carcinoma (HCC). Most HCCs enhance after the administration of MnDPDP (Teslascan). Our objective was to analyze the enhancement characteristics of tumour portal vein thrombi. Material and Methods: Thrombi affecting the main or segmental portal veins (17 cases) and the suprahepatic inferior vena cava (1 case) were retrospectively selected from a series of 128 patients studied with MR imaging before and after the administration of MnDPDP. Enhancement was assessed qualitatively and quantitatively. Results: All tumour thrombi enhanced after MnDPDP administration. The enhancement was more conspicuous in the GRE images. On the quantitative evaluation, the portal thrombus enhancement was greater for GRE images than SE images. Portal thrombi enhanced more than the liver and the HCCs. There was a significant difference between the enhancement of the HCCs and the thrombi with both MR imaging techniques. (orig./AJ)

  7. Light controlled spin properties and radiative coupling of CdSe based quantum dots

    International Nuclear Information System (INIS)

    Schmidt, T.; Worschech, L.; Scheibner, M.; Forchel, A.; Slobodskyy, T.; Schmidt, G.; Molenkamp, L.W.; Passow, T.; Hommel, D.

    2007-01-01

    The authors have studied the photoluminescence of large and small ensembles of CdSe based quantum dots (QDs) in magnetic fields for different polarizations and powers of the exciting laser light. By means of polarization spectroscopy the g factors and spin lifetimes were determined for semimagnetic CdMnSe QDs with nominal Mn contents of 0%, 1% and 2%. Also the corresponding exciton lifetimes were analyzed. A sign reversal of the QD exciton g factor was identified comparing the polarization of QD luminescence with 0% and 2% Mn. For small excitation powers QDs with 1% Mn have a vanishing small value of g. Interestingly, by ramping up the excitation power of the exciting laser the exciton g factor increases by up to a factor of 30. Different heating mechanism were identified by characteristic power dependencies. For low excitation powers indirect heating of the spin systems occurs whereas above a critical power direct heating due to photoexcited carriers dominates. It is also demonstrated that in CdMnSe QDs the circular polarization of the luminescence can be inverted solely controlled by the laser power. Applying mesa techniques, collective radiance of QDs is demonstrated. For that purpose the radiative lifetimes of QDs with such a density that there are many dots within an area proportional to the square of the optical wavelength were studied for different numbers of QDs removed from that area. A comparison of photoluminescence decay times obtained for non-resonant and quasi-resonant excitation conditions and different mesa sizes is given. Radiative coupling of QDs takes place at least on the order of 150 nm. This length is comparable to the dimensions of lithographically well definable nanostructures and may therefore provide a mechanism to couple discrete quantum objects on a large scale. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Adsorption of arsenite and selenite using an inorganic ion exchanger based on Fe–Mn hydrous oxide

    KAUST Repository

    Szlachta, Małgorzata; Gerda, Vasyl; Chubar, Natalia

    2012-01-01

    The adsorption behaviour and mechanism of As(III) and Se(IV) oxyanion uptake using a mixed inorganic adsorbent were studied. The novel adsorbent, based on Fe(III)-Mn(III) hydrous oxides and manganese(II) carbonate, was synthesised using a hydrothermal precipitation approach in the presence of urea. The inorganic ion exchanger exhibited a high selectivity and adsorptive capacity towards As(III) (up to 47.6mg/g) and Se(IV) (up to 29.0mg/g), even at low equilibrium concentration. Although pH effects were typical for anionic species (i.e., the adsorption decreased upon pH increase), Se(IV) was more sensitive to pH changes than As(III). The rates of adsorption of both oxyanions were high. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) studies showed that the ion exchange adsorption of both anions took place via OH - groups, mainly from Fe(III) but also Mn(III) hydrous oxides. MnCO 3 did not contribute directly to As(III) and Se(IV) removal. A higher adsorptive capacity of the developed material towards As(III) was partly due to partial As(III) oxidation during adsorption. © 2011 Elsevier Inc.

  9. The Effect of Powder Ball Milling on the Microstructure and Mechanical Properties of Sintered Fe-Cr-Mo-Mn-(Cu) Steel

    Science.gov (United States)

    Kulecki, P.; Lichańska, E.

    2017-12-01

    The effect of ball milling powder mixtures of Höganäs pre-alloyed iron Astaloy CrM, low-carbon ferromanganese Elkem, elemental electrolytic Cu and C-UF graphite on the sintered structure and mechanical properties was evaluated. The mixing was conducted using Turbula mixer for 30 minutes and CDI-EM60 frequency inverter for 1 and 2 hours. Milling was performed on 150 g mixtures with (in weight %) CrM + 1% Mn, CrM + 2% Mn, CrM + 1% Mn + 1% Cu and CrM + 2% Mn + 1% Cu, all with 0.6%C. The green compacts were single pressed at 660 MPa according to PN-EN ISO 2740. Sintering was carried out in a laboratory horizontal furnace Carbolite STF 15/450 at 1250°C for 60 minutes in 5%H2 - 95%N2 atmosphere with a heating rate of 75°C/min, followed by sintering hardening at 60°C/min cooling rate. All the steels were characterized by martensitic structures. Mechanical testing revealed that steels based on milled powders have slightly higher mechanical properties compared to those only mixed and sintered. The best combination of mechanical properties, for ball milled CrM + 1% Mn + 1% Cu was UTS 1046 MPa, TRS 1336 MPa and A 1.94%.

  10. Characteristics of molybdenum bilayer back contacts for Cu(In,Ga)Se2 solar cells on Ti foils

    International Nuclear Information System (INIS)

    Roger, Charles; Noël, Sébastien; Sicardy, Olivier; Faucherand, Pascal; Grenet, Louis; Karst, Nicolas; Fournier, Hélène; Roux, Frédéric; Ducroquet, Frédérique; Brioude, Arnaud; Perraud, Simon

    2013-01-01

    Molybdenum back contact properties are critical for Cu(In,Ga)Se 2 (CIGS) solar cell performance on metallic substrates. In this work, we investigated the properties of sputter-deposited Mo bilayer back contacts on Ti foils. The morphology, electrical resistivity, optical reflectance and residual mechanical stress of the bottom Mo layer were modified by varying the working pressure during its deposition. Working pressures ranging from 0.27 Pa to 4.00 Pa were used. The top Mo layer was deposited using constant conditions at a pressure of 0.13 Pa. It was demonstrated that unlike a Mo monolayer, the use of a Mo bilayer allows controlling the mechanical stress at the Mo/CIGS interface without degrading the optical reflectance and the electrical resistance of the back contact. It was also found that the morphology of the bottom Mo layer affects the growth of the top Mo layer, resulting in a modified back contact surface morphology. This induces changes in the crystalline orientation of the CIGS layer. The resulting solar cell characteristics strongly vary as a function of the bottom Mo layer deposition pressure. A bottom Mo layer growth at 2.93 Pa allows improving the solar cell conversion efficiency by 1.5 times compared to a bottom Mo layer deposited at 0.27 Pa. Using the improved Mo bilayer back contact, a maximum solar cell efficiency of 10.0% was obtained without sodium addition nor anti-reflection coating. - Highlights: • Mo bilayer back contacts for Cu(In,Ga)Se 2 solar cells were grown on Ti substrates. • The sputtering pressure of the bottom Mo layer was varied between 0.27 Pa and 4 Pa. • The top Mo layer controls the optical and electrical properties of the back contact. • The structure of the bottom Mo layer influences the morphology of the top Mo layer. • The back contact affects the CIGS texture, device series resistance and efficiency

  11. Repair by weld of steam and gas turbine rotors made of Cr-Mo-V steel; Reparacion por soldadura de rotores de turbinas de vapor y de gas fabricados con aceros al Cr-Mo-V

    Energy Technology Data Exchange (ETDEWEB)

    Mazur C, Zdzislaw; Hernandez R, Alejando [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico); Orozco S, Julian; Banuelos P, Jose E. [Comision Federal de Electricidad (Mexico)

    2003-07-01

    In this article an analysis is presented of the typical damages in steam and gas turbine rotors made of Cr-Mo-V low alloy steels. An analysis of the weldability of the Cr-Mo-V steel is carried out and a classification of the possible types of repairs of the turbine rotors is presented, starting off from the causes and ways of presentation of the faults/deterioration of the rotor materials during the operation of the turbine. With base on the damages detected in the rotor of a gas turbine of 20.65 MW, the development of the repairing technology carried out by weld in site is presented. After the repair process, the rotor was put again in operation. [Spanish] En este articulo se presenta un analisis de los danos tipicos en rotores de turbinas de vapor y de gas fabricados con aceros de baja aleacion al Cr-Mo-V. Se lleva a cabo un analisis de la soldabilidad de los aceros al Cr-Mo-V y se presenta una clasificacion de los posibles tipos de reparaciones de los rotores de turbinas, partiendo de las causas y modos de presentacion de las fallas/deterioro del material de los rotores durante la operacion de la turbina. Con base en los danos detectados en el rotor de una turbina de gas de 20.65 MW, se presenta el desarrollo de la tecnologia de reparacion por soldadura llevada a cabo en sitio. Despues del proceso de reparacion, el rotor fue puesto nuevamente en servicio.

  12. The effect of Na on Cu-K-In-Se thin film growth

    Science.gov (United States)

    Muzzillo, Christopher P.; Tong, Ho Ming; Anderson, Timothy J.

    2018-04-01

    Co-evaporation of Cu-KF-In-Se was performed on substrates with varied Na supply. Compositions of interest for photovoltaic absorbers were studied, with ratios of (K + Cu)/In ∼ 0.85 and K/(K + Cu) ∼ 0-0.57. Bare soda-lime glass (SLG) substrates had the highest Na supply as measured by secondary ion mass spectrometry, while SLG/Mo and SLG/SiO2/Mo substrates led to 3x and 3000x less Na in the growing film, respectively. Increased Na supply favored Cu1-xKxInSe2 (CKIS) alloy formation as proven by X-ray diffraction (XRD), while decreased Na supply favored the formation of CuInSe2 + KInSe2 mixed-phase films. Scanning electron microscopy and energy dispersive X-ray spectroscopy revealed the KInSe2 precipitates to be readily recognizable planar crystals. Extrinsic KF addition during film growth promoted diffusion of Na out from the various substrates and into the growing film, in agreement with previous reports. Time-resolved photoluminescence showed enhanced minority carrier lifetimes for films with moderate K compositions (0.04 interdependency can be used to engineer alkali metal bonding in Cu(In,Ga)(Se,S)2 absorbers to optimize both initial and long-term photovoltaic power generation.

  13. Simultaneous extractive-photometric determination of Zr and Mo in multicomponent alloys

    International Nuclear Information System (INIS)

    Kutyrev, I.M.; Chernysheva, G.M.; Chebotnikovz, Yu.A.; Basargin, N.N.

    2000-01-01

    Nonaqueous buffer solutions of different acidity are developed for simultaneous photometric determination of Zr and Mo in the extract. Trioctylamine extraction system in toluene - sulfuric acid - molybdenum, zirconium provides selective isolation of the aforementioned elements in one extraction and makes it possible to remove the interfering effect of Fe(2,3), Co(2), Ni(2), Cu(2), Al(3), Ti(4), Cr(3), Mn(2), V(4), Si(4). The reliability of the method is confirmed by determination of the elements in SS123v standard sample [ru

  14. Tuning the p-type Schottky barrier in 2D metal/semiconductor interface:boron-sheet on MoSe2, and WSe2

    Science.gov (United States)

    Couto, W. R. M.; Miwa, R. H.; Fazzio, A.

    2017-10-01

    Van der Waals (vdW) metal/semiconductor heterostructures have been investigated through first-principles calculations. We have considered the recently synthesized borophene (Mannix et al 2015 Science 350 1513), and the planar boron sheets (S1 and S2) (Feng et al 2016 Nat. Chem. 8 563) as the 2D metal layer, and the transition metal dichalcogenides (TMDCs) MoSe2, and WSe2 as the semiconductor monolayer. We find that the energetic stability of those 2D metal/semiconductor heterojunctions is mostly ruled by the vdW interactions; however, chemical interactions also take place in borophene/TMDC. The electronic charge transfer at the metal/semiconductor interface has been mapped, where we find a a net charge transfer from the TMDCs to the boron sheets. Further electronic structure calculations reveal that the metal/semiconductor interfaces, composed by planar boron sheets S1 and S2, present a p-type Schottky barrier which can be tuned to a p-type ohmic contact by an external electric field.

  15. Rashba effect and enriched spin-valley coupling in Ga X /M X2 (M = Mo, W; X = S, Se, Te) heterostructures

    Science.gov (United States)

    Zhang, Qingyun; Schwingenschlögl, Udo

    2018-04-01

    Using first-principles calculations, we investigate the electronic properties of the two-dimensional Ga X /MX 2 (M = Mo, W; X = S, Se, Te) heterostructures. Orbital hybridization between Ga X and MX 2 is found to result in Rashba splitting at the valence-band edge around the Γ point, which grows for increasing strength of the spin-orbit coupling in the p orbitals of the chalcogenide atoms. The location of the valence-band maximum in the Brillouin zone can be tuned by strain and application of an out-of-plane electric field. The coexistence of Rashba splitting (in-plane spin direction) and band splitting at the K and K' valleys (out-of-plane spin direction) makes Ga X /MX 2 heterostructures interesting for spintronics and valleytronics. They are promising candidates for two-dimensional spin-field-effect transistors and spin-valley Hall effect devices. Our findings shed light on the spin-valley coupling in van der Waals heterostructures.

  16. Electronic and magnetic properties of MoSe2 armchair nanoribbons controlled by the different edge structures

    Science.gov (United States)

    Zhang, Hui; Zhao, Xu; Gao, Yonghui; Wang, Haiyang; Wang, Tianxing; Wei, Shuyi

    2018-03-01

    Tow-dimensional materials obviously have potential applications in next-generation nanodevices because of their extraordinary physical and chemical properties and the demands of the market. Using first-principle calculation based on density functional theory, we explore electronic and magnetic properties of the different nanoribbons with various edge structures, namely, with hydrogenation or not. In addition, we also calculate the binding energy to analyze the stability of the nanoribbon. Our calculations tell us that the passivated nanoribbons have the positive binding energies, which indicates the passivated nanoribbons are relative stable and hydrogenation can improve the stability of the bare nanoribbons due to the reduction of the dangling bonds. Among of them, full hydrogenation has the highest stability. We find all the nanoribbons with full and without hydrogenation are nonmagnetic semiconductors. It is worth mentioning that hydrogenation can induce the bare nanoribbons to transform gradually from indirect band gap semiconductor to direct band gap semiconductor, even to half-metal. In addition, the magnetic moment of the bare nanoribbon change bit by bit as the rate of hydrogenation increases. When the edge atoms are fully hydrogenated, the magnetic moment return to zero. What's more, our research results still confirm that electronic and magnetic properties of the nanorribons without and with different edge passivation are mainly contributed by the atoms at the edges. These studies about MoSe2 nanoribbons will shed light on the further development of the relevant nanodevices in versatile applications, such as spintronics and energy harvesting.

  17. ¿Cómo enviar mensajes a extraterrestres?

    Directory of Open Access Journals (Sweden)

    Comité Seti

    2015-01-01

    Full Text Available Durante más de treinta años, los humanos han utilizado la tecnología de radio para buscar evidencia de inteligencia extraterrestre -ETI-. Colectivamente, estos esfuerzos se conocen como SETI. Si SETI detecta exitosamente una civilización extraterrestre, surgirá la pregunta de si la humanidad debe intentar establecer comunicación con otra civilización y cómo, ¿Cuál debe ser el procedimiento para tomar la decisión? ¿Cuál debe ser el contenido del mensaje? ¿Quién debe decidir? Las mismas preguntas se pueden aplicar a las propuestas con respecto al envío de señales en ausencia de su detección.

  18. 1D and 3D Polymeric Manganese(II) Thiolato Complexes: Synthesis, Structure, and Properties of    ∞3[Mn4(SPh)8] and ∞1[Mn(SMes)2].

    Science.gov (United States)

    Eichhöfer, Andreas; Lebedkin, Sergei

    2018-01-16

    Reactions of [Mn{N(SiMe 3 ) 2 } 2 ] 2 with 2.1 equiv of RSH, R = Ph or Mes = C 6 H 2 -2,4,6-(CH 3 ) 3 , yield compounds of the formal composition "Mn(SR) 2 ". Single-crystal X-ray diffraction reveals that ∞ 1 [Mn(SMes) 2 ] forms one-dimensional chains in the crystal via μ 2 -SMes bridges, whereas ∞ 3 [Mn 4 (SPh) 8 ] comprises a three-dimensional network in which adamantanoid cages composed of four Mn atoms and six μ 2 -bridging SPh ligands are connected in three dimensions by doubly bridging SPh ligands. Thermogravimetric analysis and powder diffractometry indicate an reversible uptake of solvent molecules (tetrahydrofuran) into the channels of ∞ 1 [Mn(SMes) 2 ]. Magnetic measurements reveal antiferromagnetic coupling for both compounds with J = -8.2 cm -1 ( ∞ 1 [Mn(SMes) 2 ]) and -10.0 cm -1 ( ∞ 3 [Mn 4 (SPh) 8 ]), respectively. Their optical absorption and photoluminescence (PL) excitation spectra display characteristic d-d bands of Mn 2+ ions in the visible spectral region. Both compounds emit bright phosphorescence at ∼800 nm at low temperatures (SMes) 2 ] retains a moderately intense emission at ambient temperature (with a quantum yield of 1.2%). Similar PL properties are also found for the related selenolate complexes ∞ 1 [Mn(SeR) 2 ] (R = Ph, Mes).

  19. ¿Cómo procesa el cerebro los gestos icónicos?

    Directory of Open Access Journals (Sweden)

    Iván Sánchez Borges

    2018-05-01

    Full Text Available Las personas cuando se comunican están constantemente recibiendo información que no siempre viene solo del lenguaje verbal. La comunicación no verbal también colabora en cómo se produce y comprende dicha información. Un claro ejemplo es la dificultad que tienen los oradores para comunicar acciones. Por ejemplo, es difícil explicar cómo atarse los zapatos si no va acompañado por gestos. Diversos estudios recientes con medidas electrofisiológicas de la respuesta cerebral han comprobado que los gestos icónicos implican procesos semánticos similares a las palabras o las imágenes, y que además pueden modular, facilitar y enriquecer el procesamiento del lenguaje.

  20. Electronic structures of B1 MoN, fcc Mo2N, and hexagonal MoN

    International Nuclear Information System (INIS)

    Ihara, H.; Kimura, Y.; Senzaki, K.; Kezuka, H.; Hirabayashi, M.

    1985-01-01

    The electronic structures of B1 MoN, fcc Mo 2 N, and hexagonal MoN were observed by photoelectron spectroscopic measurement. The B1-MoN phase has been predicted to be a high-T/sub c/ superconductor because of a large density of states at Fermi level. The observed electronic structure of the stoichiometric B1-MoN phase is different from that of the real B1-MoN type. The nitrogen excess B1-MoN/sub x/ (x> or =1.3) phase, however, shows the B1-type electronic structure. This is explained by the occurrence of a nitrogen vacancy in the apparent stoichiometric B1 phase and the occupation of the nitrogen vacancy in the nitrogen-excess B1 phase. This property is related to the previously reported low T/sub c/ of the B1-MoN crystals

  1. Utilization of macrominerals and trace elements in pregnant heifers with distinct feed efficiencies.

    Science.gov (United States)

    Dias, R S; Montanholi, Y R; Lopez, S; Smith, B; Miller, S P; France, J

    2016-07-01

    The objective of the study was to evaluate utilization of dietary minerals and trace elements in pregnant heifers with distinct residual feed intakes (RFI). Feed intake, body weight (BW), and body composition traits were recorded in 36 crossbred heifers over a period of 37 wk, starting shortly after weaning at 8.3 (0.10; standard deviation) mo of age with an average BW of 276 (7.8) kg. Both BW and body composition were monitored regularly throughout the study, whereas individual feed intake was assessed during the last 84 d of the trial. Data recorded were used to calculate RFI for each heifer. Heifers were ranked based on RFI and assigned to high (n=14) or low (n=10) RFI groups. After the RFI study, 24 selected heifers [age 18.2 (0.14) mo; 87.5 (4.74) d in gestation; 497 (8.5) kg of BW] were used in an indirect digestibility trial (lignin as internal marker). Heifers were fed a ration containing corn silage, haylage, and a mineral premix in which Ca, P, K, Na, Mg, S, Cu, Fe, Mn, Mo, Se, Zn, and Co were provided in the diet according to National Research Council requirements of pregnant replacement heifers. The digestibility trial lasted 1 wk, during which samples of feces were gathered twice daily, and blood and liver biopsy samples were collected on the last day. We noted no significant differences between low- and high-RFI heifers in dry matter digestibility. Apparent absorption of Cu, Zn, and Mn was increased in heifers with low RFI, and apparent absorption of Co tended to be greater for these animals. Concentrations of macrominerals and trace elements in serum of pregnant heifers were similar for both groups except for Se, which was increased in the serum of low-RFI heifers. Liver concentrations of Cu, Fe, Mn, Mo, Se, and Zn did not differ between low- and high-RFI heifers. In conclusion, whereas improved absorption of some trace elements (Cu, Zn, Mn, and Co) and increased Se serum concentration appear to be associated with superior feed efficiency in pregnant

  2. Excellent mechanical properties and resistance to cavitation erosion for an ultra-low carbon CrMnN stainless steel through quenching and partitioning treatment

    Science.gov (United States)

    Zhou, Ze-an; Fu, Wan-tang; Zhu, Zhe; Li, Bin; Shi, Zhong-ping; Sun, Shu-hua

    2018-05-01

    The retained austenite content (RAC), the mechanical properties, and the resistance to cavitation erosion (CE) of the 00Cr13Mn8MoN steel after quenching and partitioning (Q&P) processing were investigated. The results show that the Q&P process affected the RAC, which reached the maximum value after partitioning at 400°C for 10 min. The tensile strength of the steel slightly decreased with increasing partitioning temperature and time. However, the elongation and product of strength and elongation first increased and then decreased. The sample partitioned at 400°C for 10 min exhibited the optimal property: a strength-ductility of 23.8 GPa·%. The resistance to CE for the 00Cr13Mn8MoN steel treated by the Q&P process was improved due to work hardening, spalling, and cavitation-induced martensitic transformation of the retained austenite.

  3. Paneles Solares ¿Cómo funcionan? ¿Cuál es su verdadero precio?

    OpenAIRE

    Carreón Juárez, Héctor J.; Saravia Garza, Andrés E.; Escamilla Guerra, Fermín; Gómez de la Garza, Pablo

    2017-01-01

    Es un infograma en el cual queremos invitar a las mentes jóvenes a que utilizen el recurso de los paneles solares, haciéndoles saber de manera breve cómo funcionan y cómo se comporta la CFE con respecto a eso y cuánto dinero tendrían que invertir las familias en México.

  4. Kinetic Investigations of SiMn Slags From Different Mn Sources

    Science.gov (United States)

    Kim, Pyunghwa Peace; Tangstad, Merete

    2018-03-01

    The kinetics of MnO and SiO2 reduction were investigated for Silicomanganese (SiMn) slags using a Thermogravimetric analysis (TGA) between 1773 K and 1923 K (1500 °C and 1650 °C) under CO atmospheric pressure. The charge materials were based on Assmang ore and HC FeMn Slag. Rate models for MnO and SiO2 reduction were applied to describe the metal-producing rates, as shown by the following equations: r_{MnO} = k_{MnO} × A × ( {a_{MnO} - {a_{Mn} }/{K_{T }}} ) r_{{{SiO}2 }} = k_{SiO2} × A × ( {a_{{{SiO}2 }} - {a_{Si} }/{K_{T }}} ). The results show that the choice of raw materials in the charge considerably affected the reduction rate of MnO and SiO2. The highest reduction rate was found to be from charges using HC FeMn slag. The difference in the driving forces was insignificant among the SiMn slags, and the similar slag viscosities could not explain the different reduction rates. Instead, the difference is attributed to small amounts of sulfur and the amount of iron in the charge. In addition, the rate models were applicable to describe the reduction of MnO and SiO2 in SiMn slags.

  5. Welding and corrosion resistance of the new nitrogen alloyed steel X2 CrNiMnMoN241764

    International Nuclear Information System (INIS)

    Arit, N.; Henser, H.; GroB, V.

    1994-01-01

    Remanit 4565 S is a new developed nitrogen alloyed austenitic stainless steel. Characteristic features are: improved strength and toughness, delayed precipitation of carbides and intermetallic phases, improved corrosion resistance. Welding fabrication is possible without the risk of pore formation. TIG-welded joints are as resistant as the base metal, using filler metal SG-NiCr 20 Mo 15 (Thermanit Nimo C) respectively SG-NiCr 28 Mo(Thermanit 30/40 E) according to the area of application. (Author) 8 refs

  6. Characteristics of molybdenum bilayer back contacts for Cu(In,Ga)Se{sub 2} solar cells on Ti foils

    Energy Technology Data Exchange (ETDEWEB)

    Roger, Charles, E-mail: charles.rgr@gmail.com [CEA, LITEN, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France); Noël, Sébastien; Sicardy, Olivier; Faucherand, Pascal; Grenet, Louis; Karst, Nicolas; Fournier, Hélène; Roux, Frédéric [CEA, LITEN, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France); Ducroquet, Frédérique [IMEP-LAHC, Minatec, Grenoble-INP, CNRS UMR 5130, 38016 Grenoble (France); Brioude, Arnaud [Laboratoire des Multimatériaux et Interfaces, UMR 5615, Villeurbanne (France); Perraud, Simon [CEA, LITEN, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2013-12-02

    Molybdenum back contact properties are critical for Cu(In,Ga)Se{sub 2} (CIGS) solar cell performance on metallic substrates. In this work, we investigated the properties of sputter-deposited Mo bilayer back contacts on Ti foils. The morphology, electrical resistivity, optical reflectance and residual mechanical stress of the bottom Mo layer were modified by varying the working pressure during its deposition. Working pressures ranging from 0.27 Pa to 4.00 Pa were used. The top Mo layer was deposited using constant conditions at a pressure of 0.13 Pa. It was demonstrated that unlike a Mo monolayer, the use of a Mo bilayer allows controlling the mechanical stress at the Mo/CIGS interface without degrading the optical reflectance and the electrical resistance of the back contact. It was also found that the morphology of the bottom Mo layer affects the growth of the top Mo layer, resulting in a modified back contact surface morphology. This induces changes in the crystalline orientation of the CIGS layer. The resulting solar cell characteristics strongly vary as a function of the bottom Mo layer deposition pressure. A bottom Mo layer growth at 2.93 Pa allows improving the solar cell conversion efficiency by 1.5 times compared to a bottom Mo layer deposited at 0.27 Pa. Using the improved Mo bilayer back contact, a maximum solar cell efficiency of 10.0% was obtained without sodium addition nor anti-reflection coating. - Highlights: • Mo bilayer back contacts for Cu(In,Ga)Se{sub 2} solar cells were grown on Ti substrates. • The sputtering pressure of the bottom Mo layer was varied between 0.27 Pa and 4 Pa. • The top Mo layer controls the optical and electrical properties of the back contact. • The structure of the bottom Mo layer influences the morphology of the top Mo layer. • The back contact affects the CIGS texture, device series resistance and efficiency.

  7. EFECTO DEL Mo APLICADO POR SUMERSION A SEMILLAS DE ALGODONERO SOBRE LA RESPIRACION DE PLANTILLAS y SU GERMINACION

    Directory of Open Access Journals (Sweden)

    I Mogilner

    1965-01-01

    Full Text Available Se trataron semillas de algodonero manteniéndolas sumergidas en: a agua destilada; b sol. de molibdato de sodio 0,05 O/C, y e sol. de molibdato de amonio 0,05 % durante 24 hs. a una temperatura de 30°C, con el objeto de determinar el efecto del elemento Mo sobre la germinación y respiración.Para el ensayo de germinación se realizaron 36 repeticiones de cada variante.Cada repetición consistió en 25 semillas dispuestas en una caja de Petri entre papel de filtro humedecido. Los resultados indican que el Mo tiene un efecto deprimente sobre la germinación, significativo al 1 %. La respiración se midió 24. hs. después de terminado el tratamiento sobre radículas y cotiledones separadamente. El Mo aumenta la respiración de las radículas en forma altamente significativa. Sobre los cotiledones el Mo, acompañado por el catión sodio, deprime la respiración, y acompañado por el catión amonio la aumenta.

  8. Influencia de tratamientos térmicos de temple en las propiedades de la transformación martensítica en aleaciones metamagnéticas Ni-Mn-In-Co

    OpenAIRE

    Velasco Albéniz, Fernando

    2013-01-01

    El objetivo de este proyecto fin de carrera es el estudio del efecto de tratamientos térmicos de templado y envejecimiento post-templado en la transformación martensítica y en la temperatura de Curie en una aleación en base Ni-Mn-In-Co. En estudios anteriores se han analizado la influencia de tratamientos de temple y envejecimiento en aleaciones Ni-Mn-In, pero hasta la fecha no se ha realizado ningún estudio similar en aleaciones Ni-Mn-In-Co. Es por ello que en este proyecto se...

  9. Role of Phragmites australis (common reed) for heavy metals phytoremediation of estuarine sediments.

    Science.gov (United States)

    Cicero-Fernández, Diego; Peña-Fernández, Manuel; Expósito-Camargo, Jose A; Antizar-Ladislao, Blanca

    2016-01-01

    The ability of Phragmites australis to take up heavy metals (Co, Ni, Mo, Cd, Pb, Cr, Cu, Fe, Mn, Zn, and Hg) and other trace elements (As, Se, Ba), from estuarine sediments was investigated using a pilot plant experimental approach. Bioaccumulation (BCF) and translocation factors (TF) were calculated in vegetative and senescence periods for two populations of P. australis, from contaminated (MIC) and non-contaminated (GAL) estuarine sediments, respectively, both growing in estuarine contaminated sediment (RIA) from ría del Carmen y Boo, Santander Bay, Spain. The highest BCF values were obtained for Ni (0.43), Ba (0.43) Mo (0.36), Cr (0.35), and Cd (0.31) for plants collected from site GAL following the senescence period. The highest BCF values recorded for plants collected from MIC following the senescence period were for Mo (0.22) and Cu (0.22). Following senescence, plants collected from GAL and MIC presented TF>1 for Ni, Mo, Se, and Zn, and in addition plants collected from MIC presented TF>1 for Ba, Cr, and Mn. A substantial increase of Micedo's rhizosphere, six times higher than Galizano's rhizosphere, suggested adaptation to contaminated sediment. The evaluated communities of P. australis demonstrated their suitability for phytoremediation of heavy metals contaminated estuarine sediments.

  10. Personas que se inyectan drogas en Hermosillo, Sonora. Metodología para su registro

    Directory of Open Access Journals (Sweden)

    Angélica Ospina-Escobar

    2016-01-01

    Full Text Available Conocer el tamaño de las poblaciones es fundamental para estimar universos de necesidad, planear intervenciones y evaluarlas. La estigmatización y criminalización del uso de drogas en México hace que las personas que se las inyectan sean difíciles de alcanzar, sin embargo tienen derecho a la salud, y el Estado está obligado a garantizarla, lo que incluye diseñar acciones efectivas para prevenir el sida. En Hermosillo, Sonora, el peso de la trasmisión del virus de inmunodeficiencia humana por drogas inyectadas ha ganado relevancia en la última década, no obstante, se desconoce el tamaño de la población que se inyecta drogas. En este artículo se describe detalladamente cómo se construye una aproximación mixta de metodologías cualitativas y cuantitativas para estimar el tamaño de dicha población en Hermosillo, y se ofrecen recomendaciones para mejorar los sistemas para registrarla en los servicios de tratamiento de adicciones, y cómo potenciar las intervenciones comunitarias de reducción de daños en la ciudad.

  11. Caracterización de los aceros sinterizados obtenidos a partir de polvos prealeados Fe-1,5% Mo

    Directory of Open Access Journals (Sweden)

    Torralba, J. M.

    1995-02-01

    Full Text Available Sintered molybdenum-, copper-, nickel- alloyed steels, have been studied through the influence of the Chemical composition on different mechanical and physical properties. In all the studied steels, a constant percentage of carbon has been used, as well Fe-Mo prealloyed powders, with a 1,5% Mo content. Selected sintering conditions were close to those used in the P/M industry, potential consumer of the studied steels.

    Se estudian los aceros aleados sinterizados con molibdeno, cobre, níquel y grafito, a partir de la influencia de su composición sobre distintas propiedades mecánicas y físicas. En todos los aceros, se utilizó una composición de carbono constante, así como polvos prealeados de Fe-Mo, con 1,5% Mo. Las condiciones de sinterización elegidas han sido las más próximas a las utilizadas en la industria pulvimetalúrgica, que es el usuario potencial de los materiales estudiados.

  12. Measurement and Estimation of the 99Mo Production Yield by 100Mo(n,2n)99Mo

    Science.gov (United States)

    Minato, Futoshi; Tsukada, Kazuaki; Sato, Nozomi; Watanabe, Satoshi; Saeki, Hideya; Kawabata, Masako; Hashimoto, Shintaro; Nagai, Yasuki

    2017-11-01

    We, for the first time, measured the yield of 99Mo, the mother nuclide of 99mTc used in nuclear medicine diagnostic procedures, produced by the 100Mo(n,2n)99Mo reaction with accelerator neutrons. The neutrons with a continuous energy spectrum from the thermal energy up to about 40 MeV were provided by the C(d,n) reaction with 40 MeV deuteron beams. It was proved that the 99Mo yield agrees with that estimated by using the latest data on neutrons from the C(d,n) reaction and the evaluated cross section of the 100Mo(n,2n)99Mo reaction given in the Japanese Evaluated Nuclear Data Library. On the basis of the agreement, a systematic calculation was carried out to search for an optimum condition that enables us to produce as much 99Mo as possible with a good 99Mo/100Mo value from an economical point of view. The calculated 99Mo yield from a 150 g 100MoO3 sample indicated that about 30% of the demand for 99Mo in Japan can be met with a single accelerator capable of 40 MeV, 2 mA deuteron beams. Here, by referring to an existing 18F-fluorodeoxyglucose (FDG) distribution system we assumed that 99mTc radiopharmaceuticals formed after separating 99mTc from 99Mo can be delivered to hospitals from a radiopharmaceutical company within 6 h. The elution of 99mTc from 99Mo twice a day would meet about 50% of the demand for 99Mo.

  13. "Kar se Janezek nauči…", je premalo

    Directory of Open Access Journals (Sweden)

    Maca Jogan

    2009-12-01

    Full Text Available Vprašanje družbene neenakosti žensk in moških je v drugi polovici 20. stoletja postalo svetovni problem, ki so se ga resno lotile pomembne mednarodne organizacije (OZN in državne skupnosti (EU ter posamezne države. Zagotavljanje enakih možnosti za oba spola na vseh področjih in na vseh ravneh življenja je postalo ena prednostnih nalog EU, kajti v sodobnih družbah še obstajajo različne oblike (odkrite in zlasti prikrite diskriminacije po spolu. Avtorica v prvem delu razkriva ključne značilnosti moškosrediščnega tradicionalnega družbenega reda v zahodni civilizaciji ter predstavlja glavne značilnosti in nosilce zagotavljanja enakih možnosti žensk in moških od globalne do evropske ravni. Pomembno vlogo pri odpravljanju diskriminacije imata formalno in neformalno izobraževanje. Ker pa morajo biti tudi izobraževalci in nosilci novih vzorcev odnosov med spoloma izobraženi, je pomembno vseživljenjsko izobraževanje odraslih, zlasti tistih, ki zasedajo ključne položaje odločanja na vseh področjih življenja. Zato avtorica v drugem delu prispevka predstavlja nekatere pristope in prakse takšnega izobraževanja v drugih državah članicah EU ter v Sloveniji.

  14. Band alignment in ZnSe/Zn1-x-yCdxMnySe quantum-well structures

    International Nuclear Information System (INIS)

    Yu, W.Y.; Salib, M.S.; Petrou, A.; Jonker, B.T.; Warnock, J.

    1997-01-01

    We present a magneto-optical study of ZnSe/Zn 1-x-y Cd x Mn y Se quantum-well structures in which a suitable choice of the Cd composition leads to a system that is type I at zero magnetic field. When a magnetic field is applied perpendicular to the layers of the structure, the band edges split in such a way as to make the upper σ - (1/2, t 3/2) exciton transition type II, while the ground state σ + (-1/2, -3/2) exciton component remains type I at all field values. This alignment reduces the probability for carrier relaxation from the higher-energy exciton component and opens the possibility of hole-spin population inversion via optical pumping. copyright 1997 The American Physical Society

  15. ¿Cómo nos mira Débora Arango?

    Directory of Open Access Journals (Sweden)

    Ricardo Sánchez

    1996-01-01

    Full Text Available ¿Cómo la miraban sus contemporáneos y cómo la miramos hoy; nosotros, gente de final del siglo y del milenio??? Tal parece una buena perspectiva para evaluar y dilucidar el sentido de su obra, hoy colgada en la Luis Ángel Arango. Inquietante en sus distintas significaciones de imágenes, formas, colores, materiales, interpelaciones. Polifónica por los caminos escogidos: el retrato, el desnudo, lo social, lo político. Figurativa y expresionista por la semántica de los lenguajes pictóricos. Realista crítica y testimonial por las tendencias conceptuales y de escuela en que se manifiesta su arte.

  16. Mass spectrometric determination of stability of gaseous BaMoO2, Ba2MoO4, Ba2MoO5, Ba2Mo2O8 molecules

    International Nuclear Information System (INIS)

    Kudin, L.S.; Balduchchi, Dzh.; Dzhil'i, G.; Gvido, M.

    1982-01-01

    During the mass spectrometric investigation of BaCrO 4 evaporation Cr + , Ba + , BaO + main ions are recorded as well as BaMoO 4 + , BaMoO 3 + , BaMoO 2 + , BaMoO + , BaMoO 4 + , Ba 2 MoO 5 + , BaMo 2 O 8 + ions - the products of ionization of three-component (Ba, Mo, M) molecules, forming as a result of substance chemical interaction with the material of an effusion cell (Mo). Heats of formation of BaMoO 2 , Ba 2 MoO 4 , Ba 2 MoO 5 and Ba 2 Mo 2 O 8 molecules which constituted - 577+-70, -1343+-115, -1464+-70, -2393+-90 k J/mol respectively are determined on the base of the analysis of curves of ionisation efficiency and of reaction heats Ba 2 MoO 5 =BaO+BaMoO 4 , ΔH 0 0 =322+-60 kJ/mol Ba 2 Mo 2 O 8 =2BaMoO 4 , ΔH 0 0 =351+-80 kJ/mol calculated with the use of third low of thermodynamics [ru

  17. Advanced Precursor Reaction Processing for Cu(InGa)(SeS)2 Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Shafarman, William N. [Univ. of Delaware, Newark, DE (United States)

    2015-10-12

    This project “Advanced Precursor Reaction Processing for Cu(InGa)(SeS)2 Solar Cells”, completed by the Institute of Energy Conversion (IEC) at the University of Delaware in collaboration with the Department of Chemical Engineering at the University of Florida, developed the fundamental understanding and technology to increase module efficiency and improve the manufacturability of Cu(InGa)(SeS)2 films using the precursor reaction approach currently being developed by a number of companies. Key results included: (1) development of a three-step H2Se/Ar/H2S reaction process to control Ga distribution through the film and minimizes back contact MoSe2 formation; (2) Ag-alloying to improve precursor homogeneity by avoiding In phase agglomeration, faster reaction and improved adhesion to allow wider reaction process window; (3) addition of Sb, Bi, and Te interlayers at the Mo/precursor junction to produce more uniform precursor morphology and improve adhesion with reduced void formation in reacted films; (4) a precursor structure containing Se and a reaction process to reduce processing time to 5 minutes and eliminate H2Se usage, thereby increasing throughput and reducing costs. All these results were supported by detailed characterization of the film growth, reaction pathways, thermodynamic assessment and device behavior.

  18. 99Mo Yield Using Large Sample Mass of MoO3 for Sustainable Production of 99Mo

    Science.gov (United States)

    Tsukada, Kazuaki; Nagai, Yasuki; Hashimoto, Kazuyuki; Kawabata, Masako; Minato, Futoshi; Saeki, Hideya; Motoishi, Shoji; Itoh, Masatoshi

    2018-04-01

    A neutron source from the C(d,n) reaction has the unique capability of producing medical radioisotopes such as 99Mo with a minimum level of radioactive waste. Precise data on the neutron flux are crucial to determine the best conditions for obtaining the maximum yield of 99Mo. The measured yield of 99Mo produced by the 100Mo(n,2n)99Mo reaction from a large sample mass of MoO3 agrees well with the numerical result estimated with the latest neutron data, which are a factor of two larger than the other existing data. This result establishes an important finding for the domestic production of 99Mo: approximately 50% of the demand for 99Mo in Japan could be met using a 100 g 100MoO3 sample mass with a single accelerator of 40 MeV, 2 mA deuteron beams.

  19. Investigations on the behaviour of reactor pressure vessel material 20 MnMoNi 55 during heat and stress relieving treatments. Vol. 1 and 2

    International Nuclear Information System (INIS)

    Blind, D.; Schroeder-Obst, D.; Herz, K.; Maidorn, C.

    1984-01-01

    Variation of various heat treatment parameters with regard to forging, hardening, tempering and stress-relieving has been applied to several heats of pressure vessel steels with the aim of testing the possibility to obtain higher notch impact energy values. On one hand the variation of heat treatment parameters within the limits of the current VdTUeV material sheet 401/4 5.80 did not result in outstanding improvements of toughness. On the other hand, when employing procedures which did not correspond to the specifications, e.g. tempering up to 100 h, an evident decrease of the upper shelf and an increase of the transition temperature could be observed. Nevertheless, the specified values were generally reached. Essentially, the observations on the test materials confirm, apart from a few exceptions, the positive practical experience with the material 20 MnMoNi 5 5. Based on these relations between thoughness and forging as well as heat treatment the manufacturer obtained, in accordance with the current research program, an outstanding improvement of toughness by means of various optimization measures which had the effect of optimal, evidently increased upper shelfs and which excluded difficulties concerning acceptance criteria, e.g. too high notch impact energy transition temperatures. (orig./IHOE) [de

  20. Physical characterization of Cu{sub 2}ZnGeSe{sub 4} thin films from annealing of Cu-Zn-Ge precursor layers

    Energy Technology Data Exchange (ETDEWEB)

    Buffière, M., E-mail: buffiere@imec.be [Imec—Partner in Solliance, Leuven (Belgium); Department of Electrical Engineering (ESAT), KU Leuven, Heverlee (Belgium); ElAnzeery, H. [Imec—Partner in Solliance, Leuven (Belgium); KACST-Intel Consortium Center of Excellence in Nano-manufacturing Applications (CENA), Riyadh (Saudi Arabia); Microelectronics System Design department, Nile University, Cairo (Egypt); Oueslati, S.; Ben Messaoud, K. [Imec—Partner in Solliance, Leuven (Belgium); KACST-Intel Consortium Center of Excellence in Nano-manufacturing Applications (CENA), Riyadh (Saudi Arabia); Department of Physics, Faculty of Sciences of Tunis, El Manar (Tunisia); Brammertz, G.; Meuris, M. [Imec Division IMOMEC — Partner in Solliance, Diepenbeek (Belgium); Institute for Material Research (IMO) Hasselt University, Diepenbeek (Belgium); Poortmans, J. [Imec—Partner in Solliance, Leuven (Belgium); Department of Electrical Engineering (ESAT), KU Leuven, Heverlee (Belgium)

    2015-05-01

    Cu{sub 2}ZnGeSe{sub 4} (CZGeSe) can be considered as a potential alternative for wide band gap thin film devices. In this work, CZGeSe thin films were deposited on Mo-coated soda lime glass substrates by sequential deposition of sputtered Cu, Zn and e-beam evaporated Ge layers from elemental targets followed by annealing at high temperature using H{sub 2}Se gas. We report on the effect of the precursor stack order and composition and the impact of the annealing temperature on the physical properties of CZGeSe thin films. The optimal layer morphology was obtained when using a Mo/Cu/Zn/Ge precursor stack annealed at 460 °C. We have observed that the formation of secondary phases such as ZnSe can be prevented by tuning the initial composition of the stack, the stack order and the annealing conditions. This synthesis process allows synthesizing CZGeSe absorber with an optical band gap of 1.5 eV. - Highlights: • Cu{sub 2}ZnGeSe{sub 4} (CZGeSe) thin films were deposited using a two-step process. • CZGeSe dense layers were obtained using a Mo/Cu/Zn/Ge precursor annealed at 460 °C. • Formation of ZnSe can be avoided by tuning the composition and order of the initial stack. • P-type CZGeSe absorber with an optical band gap of 1.5 eV was obtained.

  1. ¿Se acabaron las lágrimas? Estudio de las repuestas culturales a la violencia de género

    Directory of Open Access Journals (Sweden)

    Laura Filardo Llamas

    2017-03-01

    Full Text Available Mediante el análisis de la canción del El Huecco “Se acabaron las lágrimas”, en este artículo se busca conseguir un doble objetivo. Por un lado, comprender cómo las canciones, y otras manifestaciones culturales, sirven para responder a determinados acontecimientos sociales, como por ejemplo la violencia de género. Por otro lado, se busca identificar las estrategias discursivas que se utilizan en dicha canción para oponerse a la violencia de género, y cómo estas contribuyen a establecer una relación de empatía con el receptor. Para ello adoptamos un enfoque multimodal, que entiende que la canción es un discurso unitario compuesto de diversos modos comunicativos (texto, música e imagen, en su caso. Combinando dicho enfoque multimodal con el Análisis Crítico del Discurso pretendemos comprobar cómo las estrategias discursivas utilizadas en esta canción sirven para, al menos aparentemente, combatir creencias fuertemente arraigadas en determinados estereotipos de género.

  2. Improvements in the susceptibility to hydrogen attack and stress-relief cracking of 2 1/4Cr-1Mo steels

    International Nuclear Information System (INIS)

    Imanaka, T.; Sato, S.; Shimomura, J.; Aso, K.

    1985-01-01

    The influence of sulphur content at extremely low level on the susceptibility to hydrogen attack and stress-relief cracking in 2 1/4Cr-1Mo steels was studied. The reduction of sulphur content and/or the addition of REM (rare earth metal) or Ca in accordance with sulphur content remarkably improve the resistivity against hydrogen attack and stress-relief cracking. Micro-structural examination has showed that there exist Mn-REM-S-Al-O complex particles in the REM-added steels. It is concluded that the effect of REM on hydrogen attack and stress-relief cracking is to reduce ''the free sulphur'' in 2 1/4Cr-1Mo steels

  3. Remoción de Fe y Mn en aguas naturales por adsorción-oxidación sobre clinoptilolita

    Directory of Open Access Journals (Sweden)

    Carolina Cuchimaque Lugo

    2013-01-01

    Full Text Available En el presente trabajo de investigación se comprueba la eficiencia en la remoción de Fe y Mn de aguas naturales por el empleo de un medio adsorbente que consiste de zeolita natural (clinoptilolita, recubierta con Fe 2O3 y MnO2 a partir de FeCl3 y MnSO4, respectivamente. La zeolita por su gran capacidad de intercambio de cationes es un excelente soporte de estos óxidos. El mecanismo de la remoción es por adsorción-oxidación de estos metales sobre la superficie de la capa de óxido que cubre el grano de zeolita. En las pruebas de remoción mediante un sistema de filtración se estudiaron las variables pH, concentraciones de Fe y Mn, caudal en el a fluente y altura de la capa de la zeolita, resultando las dos últimas ser las de mayor relevancia en la remoción. Se utilizaron concentraciones de 1,0-7,0 mg/L para Fe y de 0,5-3,0 mg/L para Mn, en un rango de pH de 6,0-8,0. La eficiencia de la remoción disminuye con el aumento en la concentración de Fe, especialmente a valores de pH altos (> 7,5, por la formación de precipitados de Fe2O3 causando aceleración en la saturación del medio. No se obtuvo una diferencia significativa sobre la remoción con el empleo de los dos tipos de recubrimiento, aunque a altas concentraciones de estos metales, con la capa de Fe 2O3 se obtuvieron porcentajes de remoción un poco mayores, pero la desventaja es que con este tipo de óxido se obtuvo menor corrida de los filtros por la saturación del medio.

  4. The Mn site in Mn-doped GaAs nanowires: an EXAFS study

    International Nuclear Information System (INIS)

    D’Acapito, F; Rovezzi, M; Boscherini, F; Jabeen, F; Bais, G; Piccin, M; Rubini, S; Martelli, F

    2012-01-01

    We present an EXAFS study of the Mn atomic environment in Mn-doped GaAs nanowires. Mn doping has been obtained either via the diffusion of the Mn used as seed for the nanowire growth or by providing Mn during the growth of Au-induced wires. As a general finding, we observe that Mn forms chemical bonds with As but is not incorporated in a substitutional site. In Mn-induced GaAs wires, Mn is mostly found bonded to As in a rather disordered environment and with a stretched bond length, reminiscent of that exhibited by MnAs phases. In Au-seeded nanowires, along with stretched MnAs coordination, we have found the presence of Mn in a MnAu intermetallic compound. (paper)

  5. Antiferromagnetic MnN layer on the MnGa(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero-Sánchez, J., E-mail: guerrero@cnyn.unam.mx; Takeuchi, Noboru

    2016-12-30

    Highlights: • A ferromagnetic Gallium terminated surface is stable before N incorporation. • After N incorporation, an antiferromagnetic MnN layer becomes stable in a wide range of chemical potential. • Spin density distribution shows an antiferromagnetic/ferromagnetic (MnN/MnGa) arrangement at the surface. - Abstract: Spin polarized first principles total energy calculations have been applied to study the stability and magnetic properties of the MnGa(001) surface and the formation of a topmost MnN layer with the deposit of nitrogen. Before nitrogen adsorption, surface formation energies show a stable gallium terminated ferromagnetic surface. After incorporation of nitrogen atoms, the antiferromagnetic manganese terminated surface becomes stable due to the formation of a MnN layer (Mn-N bonding at the surface). Spin density distribution shows a ferromagnetic/antiferromagnetic arrangement in the first surface layers. This thermodynamically stable structure may be exploited to growth MnGa/MnN magnetic heterostructures as well as to look for exchange biased systems.

  6. To Enhance Performance of Light Soaking Process on ZnS/CuIn1-xGaxSe2 Solar Cell

    Directory of Open Access Journals (Sweden)

    Yu-Jen Hsiao

    2013-01-01

    Full Text Available The ZnS/CuInGaSe2 heterojunction solar cell fabricated on Mo coated glass is studied. The crystallinity of the CIGS absorber layer is prepared by coevaporated method and the ZnS buffer layer with a band gap of 3.21 eV. The MoS2 phase was also found in the CuInGaSe2/Mo system form HRTEM. The light soaking effect of photoactive film for 10 min results in an increase in F.F. from 55.8 to 64%, but series resistivity from 7.4 to 3.8 Ω. The efficiency of the devices improved from 8.12 to 9.50%.

  7. High PEC conversion efficiencies from CuSe film electrodes modified with metalloporphyrin/polyethylene matrices

    International Nuclear Information System (INIS)

    Zyoud, Ahed; Al-Kerm, Rola S.; Al-Kerm, Rana S.; Waseem, Mansur; Mohammed, H.S. Helal; Park, DaeHoon; Campet, Guy; Sabli, Nordin; Hilal, Hikmat S.

    2015-01-01

    Enhancement of hole-transfer across CuSe electrode/liquid junction can be facilitated by coating with metalloporphyrin complexes embedded inside polyethylene matrices. - Highlights: • CuSe films were electrochemically deposited onto FTO/Glass • Annealing CuSe film electrodes enhanced PEC characteristics • PEC characteristics were further enhanced by metalloporphyrin/polyethylene matrices, yielding ∼15% efficiency • Matrix behavior as charge transfer mediator enhanced electrode conversion efficiency and stability - Abstract: Electrodeposited CuSe film electrodes have been prepared onto FTO/glass by a facile method based on earlier methods described for other systems. The films were characterized, modified by annealing and further characterized. The films were then modified by coating with tetra(-4-pyridyl) pophyrinato-manganese (MnTPyP) complexes embedded inside commercial polyethylene (PE) matrices. The effects of modifications on different film properties, such as X-ray diffraction (XRD) patterns, surface morphology, photoluminescence (PL) spectra and electronic absorption spectra were investigated. Compared with other thin film electrode systems, very high photoelectrochemical (PEC) conversion efficiency values have been observed here. Pre-annealing the CuSe films at 150°C for 2 h, followed by attaching the MnTPyP/PE matrices remarkably enhanced their PEC characteristics. The conversion efficiency was significantly enhanced, from less than 1.0% to more than 15%. Fill factor (FF) was also enhanced from ∼30% to ∼80%. Values of open-circuit potential (V OC ) and short-circuit current (J SC ) were significantly enhanced. While annealing affects uniformity, particle inter-connection and surface texture of the CuSe films, the MnTPyP complex species behaves as an additional charge-transfer mediator across the film/electrolyte junction. Optimization of PEC characteristics, using different deposition times, different annealing temperatures, different

  8. Dipole strength distribution below the giant dipole resonance in {sup 92}Mo, {sup 98}Mo and {sup 100}Mo

    Energy Technology Data Exchange (ETDEWEB)

    Rusev, G.Y.

    2006-07-01

    Investigations of the dipole-strength distributions in {sup 92}Mo, {sup 98}Mo and {sup 100}Mo were carried out by means of the method of nuclear resonance fluorescence. The low-lying excitations in the nuclides {sup 92}Mo, {sup 98}Mo and {sup 100}Mo have been studied in photon-scattering experiments at an electron energy of 6 MeV at the ELBE accelerator and at electron energies from 3.2 to 3.8 MeV at the Dynamitron accelerator. Five levels were observed in {sup 92}Mo. Five levels in {sup 98}Mo and 14 in {sup 100}Mo were identified for the first time in the energy range from 2 to 4 MeV. Dipole-strength distributions up to the neutron-separation energies in the nuclides {sup 92}Mo, {sup 98}Mo and {sup 100}Mo have been investigated at the ELBE accelerator. Because of the possible observation of transitions in the neighboring nuclei produced via ({gamma},n) reaction, additional measurements at electron energies of 8.4 and 7.8 MeV, below the neutron-separation energy, were performed on {sup 98}Mo and {sup 100}Mo, respectively. The number of transitions assigned to {sup 92}Mo, {sup 98}Mo and {sup 100}Mo is 340, 485 and 499, respectively, the main part of them being dipole transitions. Statistical properties of the observed transitions are obtained. The continuum contains the ground-state transitions as well as the branching transitions to the low-lying levels and the subsequent deexcitations of these levels. (orig.)

  9. Fourier transform spectroscopy of MnH and MnD

    Science.gov (United States)

    Balfour, W. J.; Launila, O.; Klynning, L.

    Two infrared band systems, centred near 846 nm and 1060 nm in both MnH and MnD have been rotationally analysed and shown to have a common lower state. The electronic transitions lie within the quintet manifold and are here designated c 5Σ-a 5Σ and b 5Πi-a 5Σ for the 846 and 1060 nm systems, respectively. In the 846 nm system in MnH all 10 main branches have been found in the 0-0 and 1-1 bands, while in MnD the data are complete only for 0-0. Satellite branches have been identified in the 1060 nm system and all spin and Λ-type doublings have been established. The number of assigned 0-0 branches in the 1060 nm system is 35 for MnH and 37 for MnD. Molecular constants have been determined for all three states involved. Λ-doubling diagrams are presented for b 5Πi state with v = 1, 2 levels in MnH and with the v = 2 level in MnD. Local perturbations in c5Σ (v = 1) in MnH are suspected to originate from the v = 3 level of b 5Πi.

  10. Single-layer MoS2 electronics.

    Science.gov (United States)

    Lembke, Dominik; Bertolazzi, Simone; Kis, Andras

    2015-01-20

    CONSPECTUS: Atomic crystals of two-dimensional materials consisting of single sheets extracted from layered materials are gaining increasing attention. The most well-known material from this group is graphene, a single layer of graphite that can be extracted from the bulk material or grown on a suitable substrate. Its discovery has given rise to intense research effort culminating in the 2010 Nobel Prize in physics awarded to Andre Geim and Konstantin Novoselov. Graphene however represents only the proverbial tip of the iceberg, and increasing attention of researchers is now turning towards the veritable zoo of so-called "other 2D materials". They have properties complementary to graphene, which in its pristine form lacks a bandgap: MoS2, for example, is a semiconductor, while NbSe2 is a superconductor. They could hold the key to important practical applications and new scientific discoveries in the two-dimensional limit. This family of materials has been studied since the 1960s, but most of the research focused on their tribological applications: MoS2 is best known today as a high-performance dry lubricant for ultrahigh-vacuum applications and in car engines. The realization that single layers of MoS2 and related materials could also be used in functional electronic devices where they could offer advantages compared with silicon or graphene created a renewed interest in these materials. MoS2 is currently gaining the most attention because the material is easily available in the form of a mineral, molybdenite, but other 2D transition metal dichalcogenide (TMD) semiconductors are expected to have qualitatively similar properties. In this Account, we describe recent progress in the area of single-layer MoS2-based devices for electronic circuits. We will start with MoS2 transistors, which showed for the first time that devices based on MoS2 and related TMDs could have electrical properties on the same level as other, more established semiconducting materials. This

  11. Impact of Reduced Graphene Oxide on MoS2 Grown by Sulfurization of Sputtered MoO3 and Mo Precursor Films (Postprint)

    Science.gov (United States)

    2016-05-26

    1,2 intercalation assisted exfoliation,8–11 physical vapor deposition (PVD),12,13 and a wet chemistry approach involving thermal decomposition of a... annealed MoO3, MoS2 films S1 (MoS2 using Mo precursor), S2 (MoS2 using MoO3 precursor), S1r (MoS2 using Mo pre- cursor and rGO), and S2r (MoS2 using...MoO3 precursor and rGO). The annealed MoO3 (a) shows Mo(IV) peaks which are indicative of MoO2, and Mo(VI) peaks that occur when MoO3 is present. Both

  12. Structural and morphological characterization of CdSe:Mn thin films

    Indian Academy of Sciences (India)

    Sarika Singh

    2017-06-24

    Jun 24, 2017 ... The films prepared by CBD are usu- ally composed of closely spaced nanocrystals [9]. The band-gap engineering of films is possible by tailoring the nanocrystellite size, which can be done by varying the deposition parameters. In the present work, we have successfully synthesized nanograins in CdSe and ...

  13. Valoración comparativa de las tres grandes religiones (judaímo, cristianismo, islam) /

    OpenAIRE

    Aragón Zamora, Raúl

    2013-01-01

    Se realiza una valoración comparativa de las tres grandes religiones del mundo monoteístas: cristianismo, islam y judaísmo. De gran importancia en occidente, han influido en su historia, en sus costumbres, en sus tradiciones y manera de vivir. Se analizan las diferencias que hay entre ellas y se nos muestra cómo hoy en día siguen influyendo en la vida de muchas personas.

  14. Tuning the magnetic properties of GaAs:Mn/MnAs hybrids via the MnAs cluster shape

    International Nuclear Information System (INIS)

    Nidda, H-A Krug von; Kurz, T; Loidl, A; Hartmann, Th; Klar, P J; Heimbrodt, W; Lampalzer, M; Volz, K; Stolz, W

    2006-01-01

    We report a systematic study of ferromagnetic resonance in granular GaAs:Mn/MnAs hybrids grown on GaAs(001) substrates by metal-organic vapour-phase epitaxy. The ferromagnetic resonance of the MnAs clusters can be resolved at all temperatures below T c . An additional broad absorption is observed below 60 K and is ascribed to localized charge carriers of the GaAs:Mn matrix. The anisotropy of the MnAs ferromagnetic resonance field originates from the magneto-crystalline field and demagnetization effects of the ferromagnetic MnAs clusters embedded in the GaAs:Mn matrix. Its temperature dependence basically scales with magnetization. Comparison of the observed angular dependence of the resonance field with model calculations yields the preferential orientation and shape of the clusters formed in hybrid layers of different thickness (150-1000 nm) grown otherwise at the same growth conditions. The hexagonal axes of the MnAs clusters are oriented along the four cubic GaAs space diagonals. Thin layers contain lens-shaped MnAs clusters close to the surface, whereas thick layers also contain spherical clusters in the bulk of the layer. The magnetic properties of the hexagonal MnAs clusters can be tuned by a controlled variation of the cluster shape

  15. Synthesis and characterisation of Cu{sub 2}ZnSnSe{sub 4} thin films prepared via a vacuum evaporation-based route

    Energy Technology Data Exchange (ETDEWEB)

    Volobujeva, O., E-mail: v.olga@staff.ttu.ee; Bereznev, S.; Raudoja, J.; Otto, K.; Pilvet, M.; Mellikov, E.

    2013-05-01

    Different sequentially stacked binary chalcogenide layers (CuSe, ZnSe, and SnSe) deposited by vacuum evaporation onto molybdenum covered soda-lime glass substrates were used as precursors to form Cu{sub 2}ZnSnSe{sub 4} films. The influence of the stacked binary layer sequence, substrate temperature, both the duration and speed of deposition and the post deposition treatment atmosphere on the structural and the morphological parameters of the Cu{sub 2}ZnSnSe{sub 4} thin films was studied. Our results indicate the possibility of replacing the Se{sub 2} selenisation with a thermal treatment in an SnSe{sub 2} atmosphere to avoid the selenisation of the Mo substrate and MoSe{sub 2} formation. This SnSe{sub 2} treatment forms p-type Cu{sub 2}ZnSnSe{sub 4} films with an optical band-gap of 1.14 eV and a solar cell structure with an efficiency of up to 3%. - Highlights: ► Cu{sub 2}ZnSnSe{sub 4} thin films were grown using binary precursors and selenisation. ► Composition and morphology were studied in dependence of selenisation atmosphere. ► The use of SnSe{sub 2} selenisation allows to avoid Mo substrate selenisation. ► The high quality of films is indicated by the value of their E{sub g} = 1.14 eV. ► Cu{sub 2}ZnSnSe{sub 4} thin films were in p-type conductivity and were realized as solar cells.

  16. LA TUBERCULOSIS EN EL NIÑO, ¿CÓMO SE DIAGNOSTICA?

    Directory of Open Access Journals (Sweden)

    Dra. María Elena Guarda

    2017-01-01

    Full Text Available La tuberculosis sigue siendo una epidemia mundial. En Chile en los últimos años se ha mantenido la tasa de enfermos con tuberculosis. En niños el diagnóstico es un desafio, ya que los elementos considerados como gold estándar como la baciloscopía y cultivos suelen ser falsos negativos. La prueba de tuberculina (PPD e IGRAS son pruebas complementarias con una sensibilidad y especificidad variable. La imágenes son un elemento fundamental en el contexto de un paciente sospechoso. En esta revisión se abarca la epidemiología, proceso diagnóstico (historia clínica, metodos diagnósticos, tratamiento y prevención en el niño.

  17. Phase formation in Na2MoO4 - MgMoO4 - Cr2(MoO4)3 system

    International Nuclear Information System (INIS)

    Kotova, I.Yu.; Kozhevnikova, N.M.

    1998-01-01

    Interaction within Na 2 MoO 4 - MgMoO 4 - Cr 2 (MoO 4 ) 3 ternary system is studied by X ray phase and DTA methods. State diagram of NaCr(MoO 4 ) 2 - MgMoO 4 section is plotted. Production of ternary molybdates of Na 1-x Mg 1-x Cr 1+x (MoO 4 ) 3 , where 0 ≤ x ≤ 0.3, and NaMg 3 Cr(MoO 4 ) 5 composition is ascertained [ru

  18. Instrumental neutron activation analysis of 23 individual food articles from a high altitude region. Part 1. Determination of 14 essential minor and trace elements

    International Nuclear Information System (INIS)

    Waheed, S.; Zaidi, J.H.; Ahmad, S.; Saleem, M.

    2002-01-01

    Twenty-three individual food items commonly consumed in a high altitude region (Kashmir) have been investigated using instrumental neutron activation analysis. The concentration of Ca, Cl, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Se, Sn, and Zn is reported for these food articles. For quality assurance of our data, IAEA and NIST standard reference materials have also been studied. The dietary intake of these elements was calculated in accordance with the weekly food selection habits of the residents of this area. The dietary contribution of most of these elements was found to be in agreement to the RDA/ESadi levels. The purpose was to design a database of essential elements for this area and to study the adequacy levels of these elements in different dietary items. Fairly adequate intake of Ca, Co, Cr, Cu, Fe, Mg, Mn, Mo, Se, Sn, and Zn through these foodstuffs is reported, whereas, lower intakes through these items were found for Cl, K, and Na. (author)

  19. Effect of calcination temperature on structural properties and photocatalytic activity of Mn-C-codoped TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Jianbo; Xin, Wei; Liu, Guanglong; Lin, Die; Zhu, Duanwei, E-mail: liugl@mail.hzau.edu.cn [Laboratory of Eco-Environmental Engineering Research, College of Resources and Environment, Huazhong Agricultural University (HZAU), Wuhan (China)

    2016-03-15

    Mn-C-codoped TiO{sub 2} catalysts were synthesized by modified sol-gel method based on the self-assembly technique using polyoxyethylene sorbitan monooleate (Tween 80) as template and carbon precursor and the effect of calcination temperature on their structural properties and photocatalytic activity were investigated. The XRD results showed undoped and Mn-C-codoped TiO{sub 2} calcined at 400 deg C only include anatase phase and the rutile phase appears when the calcination temperature reached to 600 deg C. UV-vis absorption spectroscopy demonstrates that the absorption spectra are strongly modified by the calcination temperature. Moreover, the Mn-C-TiO{sub 2} calcined at 400 deg C showed the lowest PL intensity due to a decrease in the recombination rate of photogenerated electrons and holes under light irradiation. The photocatalytic activity of Mn-C-codoped TiO{sub 2} were evaluated by the degradation of methyl orange (MO) under the simulate daylight irradiation and all the prepared Mn-C-codoped TiO{sub 2} samples exhibited high photocatalytic activities for photocatalytic decolorisation of methyl orange aqueous solution. At 400 deg C, the Mn-C-codoped TiO{sub 2} samples showed the highest photocatalytic activity due to synergetic effects of good crystallize ation, appropriate phase composition and slower recombination rate of photogenerated charge carriers, which further confirms the calcination temperature could affect the properties of Mn-C-codoped TiO2 significantly. (author)

  20. Identification of the interstitial Mn site in ferromagnetic (Ga,Mn)As

    CERN Document Server

    AUTHOR|(CDS)2093111; Wahl, Ulrich; Augustyns, Valerie; Silva, Daniel; Granadeiro Costa, Angelo Rafael; Houben, K; Edmonds, Kevin W; Gallagher, BL; Campion, RP; Van Bael, MJ; Castro Ribeiro Da Silva, Manuel; Martins Correia, Joao; Esteves De Araujo, Araujo Joao Pedro; Temst, Kristiaan; Vantomme, André; Da Costa Pereira, Lino Miguel

    2015-01-01

    We determined the lattice location of Mn in ferromagnetic (Ga,Mn)As using the electron emission channeling technique. We show that interstitial Mn occupies the tetrahedral site with As nearest neighbors (TAs) both before and after thermal annealing at 200 °C, whereas the occupancy of the tetrahedral site with Ga nearest neighbors (TGa) is negligible. TAs is therefore the energetically favorable site for interstitial Mn in isolated form as well as when forming complexes with substitutional Mn. These results shed new light on the long standing controversy regarding TAs versus TGa occupancy of interstitial Mn in (Ga,Mn)As.

  1. Controlled reduction of LaFe xMn yMo zO3/Al2O3 composites to produce highly dispersed and stable Fe0 catalysts: a Mössbauer investigation

    Directory of Open Access Journals (Sweden)

    Juliana Cristina Tristão

    2008-06-01

    Full Text Available In this work, controlled reduction of perovskites supported on Al2O3 was used to prepare thermally stable nanodispersed iron catalysts based on Fe0/La2O3/Al2O3. The perovskites composites LaFe0.90Mn0.08Mo0.02O3(25, 33 and 50 wt (% /Al2O3 and LaFe0.90Mn0.1O3(25 wt (% /Al2O3 were prepared and characterized by XRD, BET, TPR, SEM and Mössbauer spectroscopy. XRD for unsupported perovskite showed the formation of a single phase perovskite structure. The Mössbauer spectra of the perovskites were fitted with hyperfine field distribution model for the perovskite. Supported perovskites on Al2O3 showed a decrease of the hyperfine field in respect to unsupported perovskite, due to decrease of particle size and dispersion of the Fe3+ specimens on the support. Also showed broaden lines and relaxation effects due to the small particle size. To produce the Fe0 catalyst, the composite perovskite(25%/Al2O3 was reduced with H2 at 900, 1000 and 1100 °C for 1 hour. XRD data indicated the formation of Fe0 catalyst with particles sizes of ca. 35 nm. The Mössbauer spectrum showed the formation of metallic iron and doublets corresponding to species of octahedric Fe2+ and Fe3+ sites dispersed on Al2O3. These catalysts showed improved stability towards sintering even upon treatment at 1000 and 1100 °C under H2.

  2. Enhanced pairing of quantum critical metals near d<mo>=>3mn>+>1mn>

    Energy Technology Data Exchange (ETDEWEB)

    Fitzpatrick, A. Liam; Kachru, Shamit; Kaplan, Jared; Raghu, S.; Torroba, Gonzalo; Wang, Huajia

    2015-07-20

    We study the dynamics of a quantum critical boson coupled to a Fermi surface in intermediate energy regimes where the Landau damping of the boson can be parametrically controlled, either via large Fermi velocity or by large- N techniques. We develop a systematic approach to the BCS instability of such systems, including careful treatment of the enhanced log 2 and log 3 singularities which appear already at 1-loop. These singularities arise due to the exchange of a critical boson in the Cooper channel and are absent in Fermi liquid theory. We also treat possible instabilities to charge density wave (CDW) formation, and compare the scales Λ BCS and Λ CDW of the onset of the instabilities in different parametric regimes. We address the question of whether the dressing of the fermions into a non-Fermi liquid via interactions with the order parameter field can happen at energies > Λ BCS , Λ CDW .

  3. Development of austenitic stainless steel plate (316MN) for fast breeder reactors

    International Nuclear Information System (INIS)

    Nakazawa, Takanori; Abo, Hideo; Tanino, Mitsuru; Komatsu, Hazime.

    1989-01-01

    High creep-fatigue resistance is required for the structural materials for fast breeder reactors. As creep-fatigue life is closely related to creep-rupture ductility, the effects of C, N and Mo on creep-rupture properties were investigated with a view to improving the creep-fatigue resistance of stainless steel. Strengthening by the addition of C has a great adverse effect on rupture ductility, but N can strengthen the steel without decreasing rupture ductility. Strengthening by Mo decreases rupture ductility but this effect is small. The low-C-medium-N (0.01%C - 0.07%N) stainless steel 316 MN developed based on the findings described above exhibits only a small decrease in creep-rupture strength in long-time periods compared with the conventional 316 steel. This steel offers excellent rupture ductility and the 10,000-hour rupture strength which is about 1.2 times that of conventional steel. Moreover, this steel exhibits excellent properties in creep fatigue test. (author)

  4. Metal bioaccumulation by the freshwater alga Scenedesmus quadricauda

    International Nuclear Information System (INIS)

    Fargasova, A.

    1997-01-01

    Bioaccumulation of six metals (Cu 2+ , Cu + , Mo 6+ , Mn 2+ , V 5+ , Ni 2+ ) and their combinations by alga Scenedesmus quadricauda was determined by using radio nuclide X-ray fluorescence (RXFA). The metals were added into the cultivation medium in concentrations corresponding with EC 50 value for each metal. The obtained results indicate that Ni 2+ , Cu 2+ and Cu + were accumulated in high amounts (20%, 17.5% and 15.9%) the Mo 6+ ion ( 2+ , Ni, Mn, V; V→Ni, Mn; Mn→Ni, Cu 2+ , Cu + ; Cu + →Ni; Cu 2+ →Ni; Ni→Mn, V), enhancement (V→Cu + ; Cu 2+ →Mn; Cu + →V, Mn; Mn→V; Ni→Cu 2+ , Cu + ) and neutral effect (V→Mo; Cu 2+ →Mo; Cu + →Mo; Mn→Mo; Ni→Mo). (author)

  5. Production and characterization of LaMnO3 thin films prepared by Sol–Gel technique; Producción y caracterización de láminas delgadas de LaMnO3 preparadas por la técnica de Sol-Gel

    Energy Technology Data Exchange (ETDEWEB)

    Ebeoğlugil, M.F.

    2017-09-01

    In this study, lanthanum manganite (LaMnO3) thin films were prepared by sol-gel method for magnet technology. With this context, precursor solutions with low contact angles were synthesized from all nitrate salts of the respective cations (La, Mn), using ethanol as solvent and acetyl acetone as chelating agents. A dense amorphous film was deposited on silicon (Si) substrate. crystallization of the films was carried out at temperatures between 850 and 1000 °C. The thermal, phase, elemental, microstructural and magnetic properties of the obtained samples were determined by TG/DTA, FTIR, XRD, XPS, SEM and VSM. The results show that sustained perovskite polycrystalline films were grown on the [100]-oriented Si substrates. In addition, the films show ferromagnetic behavior. [Spanish] Se prepararon películas delgadas de manganita de lantano (LaMnO3) mediante el método Sol-gel para la tecnología del imán. Se sintetizaron soluciones precursoras con bajos ángulos de contacto a partir de sales de nitrato de los respectivos cationes (La, Mn), utilizando etanol como disolvente y acetil acetona como agente quelante. Se depositó una película amorfa y densa sobre sustrato de silicio (Si). La cristalización de las láminas se llevó a cabo a temperaturas entre 850 y 1000 ºC. El comportamiento térmico, especies químicas, microestructura y propiedades magnéticas se determinaron mediante TG / DTA, FTIR, XRD, XPS, SEM y VSM respectivamente. Los resultados muestran que láminas policristalinas de perovskita crecieron sobre los sustratos de Si orientados en el plano [100]. Finalmente, las láminas muestran un comportamiento ferromagnético.

  6. Determination of the elemental composition of cyanobacteria cells and cell fractions by atomic emission and atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Sedykh, Eh.M.; Lyabusheva, O.A.; Bannykh, L.N.; Tambiev, A.Kh.

    2005-01-01

    An approach to studying the elemental composition of cyanobacteria Spirulina platensis and Nostoc commune using a set of complementary analytical methods (ICP-AES, PAAS, and ETAAS) was proposed . The procedures were adapted for the determination of macro- and microelements (Na, K, Mg, Ca, Fe, Mn, Cu, Mo, Zn, B, and Se) in the biomass of cyanobacteria and separated cell fractions (chloroform and water-methanol extracts and precipitates). The conditions for the mineralization of biological materials were optimized for autoclave and microwave sample preparation procedures. The evaporation and atomization of Se and Mo in a graphite furnace in the presence of chloroform and methanol were studied [ru

  7. Obdelava blata na čistilni napravi Sevnica in možnost njegove uporabe

    OpenAIRE

    Strupeh, Aleš

    2016-01-01

    V nalogi bom predstavil postopke ravnanja z blatom. Ti postopki so regulirani s strani zakonodajalca, zato bom najprej pregledal aktualne uredbe, ki se direktno in indirektno nanašajo na ravnanja z blatom. V nadaljevanju bom opisal vrste in sestave ter možnosti obdelave odvečnega blata iz čistilne naprave. V nadaljevanju bom na primeru centralne čistilne naprave Sevnica pregledal trenutne procese in tehnologijo pridobivanja blata ter njegovo uporabo. Potem bom predstavil alternativni možno...

  8. Multireversible redox processes in pentanuclear bis(triple-helical) manganese complexes featuring an oxo-centered triangular {Mn(II)2Mn(III)(μ3-O)}5+ or {Mn(II)Mn(III)2(μ3-O)}6+ core wrapped by two {Mn(II)2(bpp)3}-.

    Science.gov (United States)

    Romain, Sophie; Rich, Jordi; Sens, Cristina; Stoll, Thibaut; Benet-Buchholz, Jordi; Llobet, Antoni; Rodriguez, Montserrat; Romero, Isabel; Clérac, Rodolphe; Mathonière, Corine; Duboc, Carole; Deronzier, Alain; Collomb, Marie-Noëlle

    2011-09-05

    A new pentanuclear bis(triple-helical) manganese complex has been isolated and characterized by X-ray diffraction in two oxidation states: [{Mn(II)(μ-bpp)(3)}(2)Mn(II)(2)Mn(III)(μ-O)](3+) (1(3+)) and [{Mn(II)(μ-bpp)(3)}(2)Mn(II)Mn(III)(2)(μ-O)](4+) (1(4+)). The structure consists of a central {Mn(3)(μ(3)-O)} core of Mn(II)(2)Mn(III) (1(3+)) or Mn(II)Mn(III)(2) ions (1(4+)) which is connected to two apical Mn(II) ions through six bpp(-) ligands. Both cations have a triple-stranded helicate configuration, and a pair of enantiomers is present in each crystal. The redox properties of 1(3+) have been investigated in CH(3)CN. A series of five distinct and reversible one-electron waves is observed in the -1.0 and +1.50 V potential range, assigned to the Mn(II)(4)Mn(III)/Mn(II)(5), Mn(II)(3)Mn(III)(2)/Mn(II)(4)Mn(III), Mn(II)(2)Mn(III)(3)/Mn(II)(3)Mn(III)(2), Mn(II)Mn(III)(4)/Mn(II)(2)Mn(III)(3), and Mn(III)(5)/Mn(II)Mn(III)(4) redox couples. The two first oxidation processes leading to Mn(II)(3)Mn(III)(2) (1(4+)) and Mn(II)(2)Mn(III)(3) (1(5+)) are related to the oxidation of the Mn(II) ions of the central core and the two higher oxidation waves, close in potential, are thus assigned to the oxidation of the two apical Mn(II) ions. The 1(4+) and 1(5+) oxidized species and the reduced Mn(4)(II) (1(2+)) species are quantitatively generated by bulk electrolyses demonstrating the high stability of the pentanuclear structure in four oxidation states (1(2+) to 1(5+)). The spectroscopic characteristics (X-band electron paramagnetic resonance, EPR, and UV-visible) of these species are also described as well as the magnetic properties of 1(3+) and 1(4+) in solid state. The powder X- and Q-band EPR signature of 1(3+) corresponds to an S = 5/2 spin state characterized by a small zero-field splitting parameter (|D| = 0.071 cm(-1)) attributed to the two apical Mn(II) ions. At 40 K, the magnetic behavior is consistent for 1(3+) with two apical S = 5/2 {Mn(II)(bpp)(3)}(-) and one S

  9. The crystal structures of jaguéite, Cu2Pd3Se4, and chrisstanleyite, Ag2Pd3Se4

    DEFF Research Database (Denmark)

    Topa, Dan; Makovicky, Emil; Balic Zunic, Tonci

    2006-01-01

    equipped with a CCD area-detector. The crystal structure of chrisstanleyite, ideally Ag2Pd3Se4, monoclinic a 5.676(2), b 10.342(4), c 6.341(2) Å, ß 114.996(4)º, space group P21/c, has been solved by direct methods and refi ned to an R1 index of 8.3% for 1203 unique refl ections measured with MoK X......The crystal structure of jaguéite, ideally Cu2Pd3Se4, monoclinic, a 5.672(5), b 9.909(9), c 6.264(6) Å, ß 115.40(2)º, space group P21/c, has been solved by direct methods and refi ned to an R1 index of 5.52% for 956 unique refl ections measured with MoK X-radiation on a P-4 Bruker diffractometer......(Ag)-Pd2 system of metal-metal bonds, help to stabilize the open-work structure composed of PdSe4 squares....

  10. Petrogenesis of the late Early Cretaceous granodiorite - Quartz diorite from eastern Guangdong, SE China: Implications for tectono-magmatic evolution and porphyry Cu-Au-Mo mineralization

    Science.gov (United States)

    Jia, Lihui; Mao, Jingwen; Liu, Peng; Li, Yang

    2018-04-01

    Comprehensive petrological, zircon U-Pb dating, Hf-O isotopes, whole rock geochemistry and Sr-Nd isotopes data are presented for the Xinwei and Sanrao intrusions in the eastern Guangdong Province, Southeast (SE) China, with an aim to constrain the petrogenesis, tectono-magmatic evolution and evaluate the implication for porphyry Cu-Au-Mo mineralization. The Xinwei intrusion is composed of granodiorite and quartz diorite, whilst the Sanrao intrusion consists of granodiorite. Zircon U-Pb ages show that both intrusions were emplaced at ca. 106-102 Ma. All rocks are metaluminous to weakly peraluminous, high-K calc-alkaline in composition, and they are characterized by LREEs enrichment, depletion in Nb, Ta, P, and Ti, and strongly fractionated LREEs to HREEs. The initial 87Sr/86Sr ratios range from 0.7055 to 0.7059, and εNd(t) values range from -3.9 to -3.0. Together with the relatively high εHf(t) values (-3.2 to 3.3) and low δ18O values (4.9‰ to 6.6‰), these data suggest that the Xinwei and Sanrao intrusions were derived from a mixed source: including the mantle-derived mafic magmas and lower continental crustal magmas. Fractional crystallization played an important role in the magmatic evolution of the Xinwei and Sanrao intrusions. The elemental and isotopic compositions of the Xinwei and Sanrao intrusions, as well as the high water content and oxidation state of their parental magmas, are similar to those of the ore-bearing granodiorites of the Luoboling porphyry Cu-Mo deposit in the Fujian Province, neighbouring east to the Guangdong Province, indicating that the late Early Cretaceous granodioritic intrusions in the eastern Guangdong Province may also have Cu-Au-Mo mineralization potential. The late Early Cretaceous magmatic event is firstly reported in eastern Guangdong, and represents a positive response of large-scale lithosphere extension and thinning, triggered by the changing subduction direction of the Paleo-Pacific plate from oblique subduction to

  11. Alloying as a Route to Monolayer Transition Metal Dichalcogenides with Improved Optoelectronic Performance: Mo(S1–xSex)2 and Mo1–yWyS2

    KAUST Repository

    Shi, Zhiming

    2018-04-26

    On the basis of first-principles and cluster expansion calculations, we propose an effective approach to realize monolayer transition metal dichalcogenides with sizable band gaps and improved optoelectronic performance. We show that monolayer Mo(S1–xSex)2 and Mo1–yWyS2 with x = 1/3, 2/3 and y = 1/3, 1/2, 2/3 are stable according to phonon calculations and realize 1T′ or 1T″ phases. The transition barriers from the 2H phase are lower than for monolayer MoS2, implying that the 1T′ or 1T″ phases can be achieved experimentally. Furthermore, it turns out that the 1T″ monolayer alloys with x = 1/3, 2/3 and y = 1/3, 2/3 are semiconductors with band gaps larger than 1 eV, due to trimerization. The visible light absorption and carrier mobility are strongly improved as compared to 2H monolayer MoS2, MoSe2, and WS2. Thus, the 1T″ monolayer alloys have the potential to expand the applications of transition metal dichalcogenides, for example, in solar cells.

  12. The Adsorption Langmuir Model of Transfer Metal Ti, V and Mn on System Water-Sediment in Along Side Code River, Yogyakarta

    International Nuclear Information System (INIS)

    Rini Jati Wardani; Muzakky; Agus Taftazani

    2007-01-01

    The adsorption langmuir model of transfer metal Ti, V and Mn on system water-sediment in along side Code river, Yogyakarta has been studied. For that purpose, the study is to make prediction about adsorption langmuir model of identified metal Ti, V and Mn from upstream until downstream samples water and sediment in along side Code river. The factor influenced of langmuir adsorption on transfer metal Ti, V and Mn in system water-sediment is Total Suspended Solid (TSS). The analysis showed that between TSS with metal concentration in sediment have linear correlation. The result of calculation from curve of langmuir isotherm, showed for Ti has R 2 = 0.8006 with capacities of adsorption = 0.5 mol/l and energy of adsorption = 13.286 J/mol, V has R 2 = 0.9883 with capacities of adsorption = 0.0137 mol/l and energy of adsorption = 16.64 J/mol, Mn has R 2 = 0.9624 with capacities of adsorption 0.152 mol/l and energy of adsorption = 10.51 J/mol. The conclusion from this topic about adsorption langmuir for metal Ti, V and Mn according to energy of langmuir adsorption by chemisorption process above 10 J/mo. (author)

  13. Nano-sized Mn3O4 and β-MnOOH from the decomposition of β-cyclodextrin-Mn: 2. The water-oxidizing activities.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Mostafalu, Ramin; Hołyńska, Małgorzata; Ebrahimi, Foad; Kaboudin, Babak

    2015-11-01

    Nano-sized Mn oxides contain Mn3O4, β-MnOOH and Mn2O3 have been prepared by a previously reported method using thermal decomposition of β-cyclodextrin-Mn complexes. In the next step, the water-oxidizing activities of these Mn oxides using cerium(IV) ammonium nitrate as a chemical oxidant are studied. The turnover frequencies for β-MnO(OH) and Mn3O4 are 0.24 and 0.01-0.17 (mmol O2/mol Mns), respectively. Subsequently, water-oxidizing activities of these compounds are compared to the other previously reported Mn oxides. Important factors affecting water oxidation by these Mn oxides are also discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Environmental exposures of trace elements assessed using keratinized matrices from patients with chronic kidney diseases of uncertain etiology (CKDu) in Sri Lanka.

    Science.gov (United States)

    Diyabalanage, Saranga; Fonseka, Sanjeewani; Dasanayake, D M S N B; Chandrajith, Rohana

    2017-01-01

    An alarming increase in chronic kidney disease with unknown etiology (CKDu) has recently been reported in several provinces in Sri Lanka and chronic exposures to toxic trace elements were blamed for the etiology of this disease. Keratinized matrices such as hair and nails were investigated to determine the possible link between CKDu and toxic element exposures. Elements Li, B, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Ba, Hg and Pb of hair and nails of patients and age that matched healthy controls were determined with Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The results showed that trace element contents in the hair of patients varies in the order of Zn>Fe>Al>Mn>Cu>Ba>Sr>Ni>Pb>Cr>B>Hg>Se>Mo>Co>As>Li>Cd while Fe>Al>Zn>Ni>Cu>Mn>Cr>Ba>Sr>B>Pb>Se>Mo>Co>Hg>Li>As>Cd in nail samples. The hair As levels of 0.007-0.165μgg -1 were found in CKDu subjects. However, no significant difference was observed between cases and controls. The total Se content in hair of CKDu subjects ranged from 0.043 to 0.513μgg -1 while it was varied from 0.031 to 1.15μgg -1 in controls. Selenium in nail samples varied from 0.037μgg -1 to 4.10μgg -1 in CKDu subjects and from 0.042μgg -1 to 2.19μgg -1 in controls. This study implies that substantial proportions of Sri Lankan population are Se deficient irrespective of gender, age and occupational exposure. Although some cutaneous manifestations were observed in patient subjects, chemical analyses of hair and nails indicated that patients were not exposed to toxic levels of arsenic or the other studied toxic elements. Therefore the early suggested causative factors such as exposure to environmental As and Cd, can be ruled out. Copyright © 2016 Elsevier GmbH. All rights reserved.

  15. Studi Komposisi Mineral Tepung Batu Bukit Kamang Sebagai Bahan Baku Pakan Sumber Mineral

    Directory of Open Access Journals (Sweden)

    Khalil

    2007-04-01

    Full Text Available The study was conducted to determine mineral content of limestone originated from natural deposit of Bukit Kamang for feedstuff. Six samples were prepared and chemically analyzed. The first was limestone in meal form as a product of local milling industry. Another five samples were deposit components with different color of blackish, dark blue, blue, light blue and white. There was 21 kinds of mineral determined which were divided into 3 groups: macros (Ca, P, Mg, Na, K, Cl and S, trace minerals (Mn, Zn, Fe, Cu, Se, Co and Mo and toxic elements (As, F, Hg, Cd, Pb, Ni and Cr. The results showed that Bukit Kamang’s limestone contained considerable high essential minerals of Ca, Se, Fe and Mn. The limestone consisted of 38%-40% Ca, 388 ppm Se, 295 ppm Fe and 205 ppm Mn. There were two toxic elements detected: Pb and Cd, but their concentration was found relatively low: 28 and 7 ppm, respectively.

  16. Photoproduction of the f<mn>1mn>(>1285mn>)> meson

    Energy Technology Data Exchange (ETDEWEB)

    Dickson, Ryan [Carnegie Mellon Univ., Pittsburgh, PA (United States); Schumacher, Reinhard A. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Adhikari, K. P.; Akbar, Z.; Amaryan, M. J.; Anefalos Pereira, S.; Badui, R. A.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A.; Boiarinov, S.; Briscoe, W. J.; Burkert, V. D.; Cao, T.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Chetry, T.; Ciullo, G.; Colaneri, L.; Cole, P. L.; Compton, N.; Contalbrigo, M.; Cortes, O.; Crede, V.; D' Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dugger, M.; Dupre, R.; El Alaoui, A.; El Fassi, L.; Eugenio, P.; Fanchini, E.; Fedotov, G.; Filippi, A.; Fleming, J. A.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Gothe, R. W.; Griffioen, K. A.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Holtrop, M.; Hicks, K.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jiang, H.; Jo, H. S.; Joosten, S.; Keller, D.; Khachatryan, G.; Khandaker, M.; Kim, A.; Kim, W.; Klein, F. J.; Kubarovsky, V.; Kuleshov, S. V.; Lanza, L.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Mattione, P.; McKinnon, B.; Meyer, C. A.; Mirazita, M.; Markov, N.; Mokeev, V.; Moriya, K.; Munevar, E.; Murdoch, G.; Nadel-Turonski, P.; Net, L. A.; Ni, A.; Osipenko, M.; Ostrovidov, A. I.; Park, K.; Pasyuk, E.; Phelps, W.; Pisano, S.; Pogorelko, O.; Price, J. W.; Prok, Y.; Puckett, A. J. R.; Raue, B. A.; Ripani, M.; Rizzo, A.; Rosner, G.; Roy, P.; Salgado, C.; Seder, E.; Sharabian, Y. G.; Skorodumina, Iu.; Smith, E. S.; Smith, G. D.; Sober, D.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Strakovsky, I. I.; Stankovic, I.; Strauch, S.; Sytnik, V.; Taiuti, M.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Weygand, D.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zonta, I.

    2016-06-01

    The $f_1(1285)$ meson with mass $1281.0 \\pm 0.8$ MeV/$c^2$ and width $18.4 \\pm 1.4$ MeV (FWHM) was measured for the first time in photoproduction from a proton target using CLAS at Jefferson Lab. Differential cross sections were obtained via the $\\eta\\pi^{+}\\pi^{-}$, $K^+\\bar{K}^0\\pi^-$, and $K^-K^0\\pi^+$ decay channels from threshold up to a center-of-mass energy of 2.8 GeV. The mass, width, and an amplitude analysis of the $\\eta\\pi^{+}\\pi^{-}$ final-state Dalitz distribution are consistent with the axial-vector $J^P=1^+$ $f_1(1285)$ identity, rather than the pseudoscalar $0^-$ $\\eta(1295)$. The production mechanism is more consistent with $s$-channel decay of a high-mass $N^*$ state, and not with $t$-channel meson exchange. Decays to $\\eta\\pi\\pi$ go dominantly via the intermediate $a_0^\\pm(980)\\pi^\\mp$ states, with the branching ratio $\\Gamma(a_0\\pi \\text{ (no} \\bar{K} K\\text{)}) / \\Gamma(\\eta\\pi\\pi \\text{(all)}) = 0.74\\pm0.09$. The branching ratios $\\Gamma(K \\bar{K} \\pi)/\\Gamma(\\eta\\pi\\pi) = 0.216\\pm0.033$ and $\\Gamma(\\gamma\\rho^0)/\\Gamma(\\eta\\pi\\pi) = 0.047\\pm0.018$ were also obtained. The first is in agreement with previous data for the $f_1(1285)$, while the latter is lower than the world average.

  17. Photoproduction of the f<mn>1mn>(>1285mn>)> meson

    Energy Technology Data Exchange (ETDEWEB)

    Dickson, R.; Schumacher, R. A.; Adhikari, K. P.; Akbar, Z.; Amaryan, M. J.; Anefalos Pereira, S.; Badui, R. A.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A.; Boiarinov, S.; Briscoe, W. J.; Burkert, V. D.; Cao, T.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Chetry, T.; Ciullo, G.; Colaneri, L.; Cole, P. L.; Compton, N.; Contalbrigo, M.; Cortes, O.; Crede, V.; D' Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dugger, M.; Dupre, R.; El Alaoui, A.; El Fassi, L.; Eugenio, P.; Fanchini, E.; Fedotov, G.; Filippi, A.; Fleming, J. A.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Gothe, R. W.; Griffioen, K. A.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Holtrop, M.; Hicks, K.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jiang, H.; Jo, H. S.; Joosten, S.; Keller, D.; Khachatryan, G.; Khandaker, M.; Kim, A.; Kim, W.; Klein, F. J.; Kubarovsky, V.; Kuleshov, S. V.; Lanza, L.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Mattione, P.; McKinnon, B.; Meyer, C. A.; Mirazita, M.; Markov, N.; Mokeev, V.; Moriya, K.; Munevar, E.; Murdoch, G.; Nadel-Turonski, P.; Net, L. A.; Ni, A.; Osipenko, M.; Ostrovidov, A. I.; Park, K.; Pasyuk, E.; Phelps, W.; Pisano, S.; Pogorelko, O.; Price, J. W.; Prok, Y.; Puckett, A. J. R.; Raue, B. A.; Ripani, M.; Rizzo, A.; Rosner, G.; Roy, P.; Salgado, C.; Seder, E.; Sharabian, Y. G.; Skorodumina, Iu.; Smith, E. S.; Smith, G. D.; Sober, D.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Strakovsky, I. I.; Stankovic, I.; Strauch, S.; Sytnik, V.; Taiuti, M.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Weygand, D.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zonta, I.

    2016-06-01

    The f(1)(1285) meson withmass 1281.0 +/- 0.8MeV/c(2) and width 18.4 +/- 1.4MeV (full width at half maximum) was measured for the first time in photoproduction from a proton target using CLAS at Jefferson Lab. Differential cross sections were obtained via the eta pi(+)pi(-), K+(K) over bar (0) pi(-), and (K-K0)pi(+) decay channels from threshold up to a center-of-mass energy of 2.8 GeV. The mass, width, and an amplitude analysis of the eta pi(+)pi(-) final-state Dalitz distribution are consistent with the axial-vector J(P) = 1(+) f(1)(1285) identity, rather than the pseudoscalar 0(-) eta(1295). The production mechanism is more consistent with s-channel decay of a high-mass N* state and not with t-channel meson exchange. Decays to eta pi pi go dominantly via the intermediate a(0)(+/-) (980)pi(-/+) states, with the branching ratio Gamma [a(0)pi (no (K) over barK)]/Gamma[eta pi pi (all)] = 0.74 +/- 0.09. The branching ratios Gamma (K (K) over bar pi)/Gamma(eta pi pi) = 0.216 +/- 0.033 and Gamma (gamma rho(0))/Gamma(eta pi pi) = 0.047 +/- 0.018 were also obtained. The first is in agreement with previous data for the f(1)(1285), while the latter is lower than the world average.

  18. Reacciones en estado sólido para el sistema Al-MoO3 en la fabricación de materiales compuestos Al2O3-aluminuros de Mo

    Directory of Open Access Journals (Sweden)

    Marín, J.

    2002-02-01

    Full Text Available Ceramic matrix composites reinforced with metallic particles exhibit good mechanical properties. One research line has involved the fabrication of 3A (alumina-aluminide alloys composites via in situ consolidation of aluminum reactive powders mixed with a metallic oxide. In this paper the solid state reactions for the Al-MoO3 system and the effect of the precursor compositions for obtaining Al2O3 composites and intermetallic aluminides are studied. The reactions in vacuum for the 25 °C to 750 °C temperature range, and the microstructural evolution up to 1200 °C were studied. DTA-TG and DSC were used to determine that a heating rate of 1 °C/min at the critical range of 500-600 °C, resulted in controlled aluminothermic reactions. XRD and SEM showed that in the sintered composites a microstructure composed of an Al2O3 matrix and a Mo aluminide /metallic Mo dispersed phase was present. The precursor composition affects the dispersed phase in the composite (Mo aluminides and/or metallic Mo, the relative Al2O3 /second phase quantities, and the hardness of the composite sintered at 1450 °C.

    Los materiales compuestos de matriz cerámica (CMC's de Al2O3 reforzados con partículas metálicas tienen propiedades mecánicas muy atractivas. Un área de investigación emergente es la fabricación de compuestos 3A (Alumina-Aluminide-Alloys, mediante la formación in situ de Al2O3 reforzada con metal elemental y/o aluminuros del metal, partiendo de polvos de aluminio y de óxidos metálicos. En este trabajo se estudian las reacciones en estado sólido para el sistema Al-MoO3. Las reacciones de aluminotermia se estudian en vacío para el rango de temperaturas entre 25 °C y 750 °C y su evolución microestructural hasta 1.200 °C. Mediante análisis calorimétrico (DTA-TG y DSC se determinó que para una

  19. Characterization of Mn-resistant endophytic bacteria from Mn-hyperaccumulator Phytolacca americana and their impact on Mn accumulation of hybrid penisetum.

    Science.gov (United States)

    Zhang, Wen-Hui; Chen, Wei; He, Lin-Yan; Wang, Qi; Sheng, Xia-Fang

    2015-10-01

    Three hundred Mn-resistant endophytic bacteria were isolated from the Mn-hyperaccumulator, Phytolacca americana, grown at different levels of Mn (0, 1, and 10mM) stress. Under no Mn stress, 90%, 92%, and 11% of the bacteria produced indole acetic acid (IAA), siderophore, and 1-aminocyclopropane-1-carboxylate (ACC) deaminase, respectively. Under Mn stress, 68-94%, 91-92%, and 21-81% of the bacteria produced IAA, siderophore, and ACC deaminase, respectively. Greater percentages of ACC deaminase-producing bacteria were found in the Mn-treated P. americana. Furthermore, the ratios of IAA- and siderophore-producing bacteria were significantly higher in the Mn treated plant leaves, while the ratio of ACC deaminase-producing bacteria was significantly higher in the Mn treated-roots. Based on 16S rRNA gene sequence analysis, Mn-resistant bacteria were affiliated with 10 genera. In experiments involving hybrid penisetum grown in soils treated with 0 and 1000mgkg(-1) of Mn, inoculation with strain 1Y31 was found to increase the root (ranging from 6.4% to 18.3%) and above-ground tissue (ranging from 19.3% to 70.2%) mass and total Mn uptake of above-ground tissues (64%) compared to the control. Furthermore, inoculation with strain 1Y31 was found to increase the ratio of IAA-producing bacteria in the rhizosphere and bulk soils of hybrid penisetum grown in Mn-added soils. The results showed the effect of Mn stress on the ratio of the plant growth-promoting factor-producing endophytic bacteria of P. americana and highlighted the potential of endophytic bacterium as an inoculum for enhanced phytoremediation of Mn-polluted soils by hybrid penisetum plants. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Structure of ferroelastic K3H(SeO4)2

    International Nuclear Information System (INIS)

    Ichikawa, M.; Sato, S.; Komukae, M.; Osaka, T.

    1992-01-01

    Tripotassium hydrogenbis(selenate), K 3 H(SeO 4 ) 2 , M r = 404.2, monoclinic, A2/a, a = 10.1291 (8), b = 5.9038 (5), c = 14.961 (1) A, β = 103.640 (8) 0 , V = 869.5 (1) A 3 , Z = 4, D x = 3.086 Mg m -3 , λ(Mo Kα) = 0.71073 A, μ = 9.86 mm -1 , F(000) = 760, T = 299 K, R(F) = 0.0294 for 1670 unique reflections. K 3 H(SeO 4 ) 2 is isomorphous with most M 3 H(XO 4 ) 2 -type crystals (M=K,Rb and Cs; Cs; X = S and Se); two SeO 4 groups are connected by a crystallographically symmetric hydrogen bond into a dimer. The bond distances and angles in the SeO 4 group are similar to those in Rb 3 H(SeO 4 ) 2 and Rb 3 D(SeO 4 ) 2 . The hydrogen-bond length, 2.524 (5) A, is the shortest among the members of the M 3 H(SeO 4 ) 2 family exhibiting the low-temperature phase transition. (orig.)

  1. «Governem-se vocês mesmos!» democracia e carnificina no norte de Moçambique

    Directory of Open Access Journals (Sweden)

    Harry G. West

    2008-04-01

    Full Text Available A linguagem de poder que os habitantes do planalto de Mueda falaram ao longo da transformação neoliberal da economia e política moçambicanas difere substancialmente da linguagem falada pelos reformadores democráticos, apesar dos pontos de convergência e das variações internas em ambas as linguagens. Na disjunção entre elas, os muedenses relacionaram-se criticamente com o processo de democratização em curso, articulando a sua própria visão acerca do funcionamento do poder no mundo que habitam. Equiparações à primeira vista paradoxais - como entre descentralização democrática e abandono por parte do Estado, entre liberdade individual e perigo colectivo de feitiçaria, ou entre democracia e carnificina - constituíram, afinal, formas em última instância democráticas de avaliação e de crítica às transformações ocorridas e às formas como o poder é exercido no novo contexto de capitalismo neoliberal.The language of power spoken by the inhabitants of the Mueda plateau in the course of the neoliberal transformation of Mozambican political and economic life is substantially different to the language spoken by democratic reformers, despite the commonalities and internal variations in both languages. In the rift between the languages, the Muedans adopt a critical stance towards the current process of democratization, articulating their own vision of how power operates in their world. Equivalences which are at first sight paradoxical - such as equating democratic decentralization with abandonment by the state, individual freedom with the collective danger of witchcraft, and democracy with carnage - were ultimately democratic ways of evaluating and criticizing the changes taking place and the ways in which power is used in the new context of neoliberal capitalism.

  2. Continuously increasing δ98Mo values in Neoarchean black shales and iron formations from the Hamersley Basin

    Science.gov (United States)

    Kurzweil, Florian; Wille, Martin; Schoenberg, Ronny; Taubald, Heinrich; Van Kranendonk, Martin J.

    2015-09-01

    We present Mo-, C- and O-isotope data from black shales, carbonate- and oxide facies iron formations from the Hamersley Group, Western Australia, that range in age from 2.6 to 2.5 billion years. The data show a continuous increase from near crustal δ98Mo values of around 0.50‰ for the oldest Marra Mamba and Wittenoom formations towards higher values of up to 1.51‰ for the youngest sample of the Brockman Iron Formation. Thereby, the trend in increasing δ98Mo values is portrayed by both carbonate facies iron formations and black shales. Considering the positive correlation between Mo concentration and total organic carbon, we argue that this uniformity is best explained by molybdate adsorption onto organic matter in carbonate iron formations and scavenging of thiomolybdate onto sulfurized organic matter in black shales. A temporal increase in the seawater δ98Mo over the period 2.6-2.5 Ga is observed assuming an overall low Mo isotope fractionation during both Mo removal processes. Oxide facies iron formations show lowest Mo concentrations, lowest total organic carbon and slightly lower δ98Mo compared to nearly contemporaneous black shales. This may indicate that in iron formation settings with very low organic matter burial rates, the preferential adsorption of light Mo isotopes onto Fe-(oxyhydr)oxides becomes more relevant. A similar Mo-isotope pattern was previously found in contemporaneous black shales and carbonates of the Griqualand West Basin, South Africa. The consistent and concomitant increase in δ98Mo after 2.54 billion years ago suggests a more homogenous distribution of seawater molybdate with uniform isotopic composition in various depositional settings within the Hamersley Basin and the Griqualand West Basin. The modeling of the oceanic Mo inventory in relation to the Mo in- and outflux suggests that the long-term build-up of an isotopically heavy seawater Mo reservoir requires a sedimentary sink for isotopically light Mo. The search for this

  3. Impact of reduced graphene oxide on MoS{sub 2} grown by sulfurization of sputtered MoO{sub 3} and Mo precursor films

    Energy Technology Data Exchange (ETDEWEB)

    Pacley, Shanee, E-mail: shanee.pacley@us.af.mil; Brausch, Jacob; Beck-Millerton, Emory [U.S. Air Force Research Laboratory (AFRL)/Wright Patterson Air Force Base, Wright Patterson, Ohio 45433-7707 (United States); Hu, Jianjun; Jespersen, Michael [University of Dayton Research Institute, 300 College Park, Dayton, Ohio 45469 (United States); Hilton, Al [Wyle Laboratories, 4200 Colonel Glenn Hwy, Beavercreek, Ohio 45431 (United States); Waite, Adam [University Technology Corporation, 1270 N Fairfield Rd., Beavercreek, Ohio 45432 (United States); Voevodin, Andrey A. [Department of Materials Science and Engineering, University of North Texas, 1155 Union Circle, Denton, Texas 76203 (United States)

    2016-07-15

    Monolayer molybdenum disulfide (MoS{sub 2}), a two dimensional semiconducting dichalcogenide material with a bandgap of 1.8–1.9 eV, has demonstrated promise for future use in field effect transistors and optoelectronics. Various approaches have been used for MoS{sub 2} processing, the most common being chemical vapor deposition. During chemical vapor deposition, precursors such as Mo, MoO{sub 3}, and MoCl{sub 5} have been used to form a vapor reaction with sulfur, resulting in thin films of MoS{sub 2}. Currently, MoO{sub 3} ribbons and powder, and MoCl{sub 5} powder have been used. However, the use of ribbons and powder makes it difficult to grow large area-continuous films. Sputtering of Mo is an approach that has demonstrated continuous MoS{sub 2} film growth. In this paper, the authors compare the structural properties of MoS{sub 2} grown by sulfurization of pulse vapor deposited MoO{sub 3} and Mo precursor films. In addition, they have studied the effects that reduced graphene oxide (rGO) has on MoS{sub 2} structure. Reports show that rGO increases MoS{sub 2} grain growth during powder vaporization. Herein, the authors report a grain size increase for MoS{sub 2} when rGO was used during sulfurization of both sputtered Mo and MoO{sub 3} precursors. In addition, our transmission electron microscopy results show a more uniform and continuous film growth for the MoS{sub 2} films produced from Mo when compared to the films produced from MoO{sub 3}. Atomic force microscopy images further confirm this uniform and continuous film growth when Mo precursor was used. Finally, x-ray photoelectron spectroscopy results show that the MoS{sub 2} films produced using both precursors were stoichiometric and had about 7–8 layers in thickness, and that there was a slight improvement in stoichiometry when rGO was used.

  4. Structural Stabilities of β-Ti Alloys Studied Using a New Mo Equivalent Derived from [ β/( α + β)] Phase-Boundary Slopes

    Science.gov (United States)

    Wang, Qing; Dong, Chuang; Liaw, Peter K.

    2015-08-01

    Structural stabilities of β-Ti alloys are generally investigated by an empirical Mo equivalent, which quantifies the stability contribution of each alloying element, M, in comparison to that of the major β-Ti stabilizer, Mo. In the present work, a new Mo equivalent (Moeq)Q is proposed, which uses the slopes of the boundary lines between the β and ( α + β) phase zones in binary Ti-M phase diagrams. This (Moeq)Q reflects a simple fact that the β-Ti stability is enhanced, when the β phase zone is enlarged by a β-Ti stabilizer. It is expressed as (Moeq)Q = 1.0 Mo + 0.74 V + 1.01 W + 0.23 Nb + 0.30 Ta + 1.23 Fe + 1.10 Cr + 1.09 Cu + 1.67 Ni + 1.81 Co + 1.42 Mn + 0.38 Sn + 0.34 Zr + 0.99 Si - 0.57 Al (at. pct), where the equivalent coefficient of each element is the slope ratio of the [ β/( α + β)] boundary line of the binary Ti-M phase diagram to that of the Ti-Mo. This (Moeq)Q is shown to reliably characterize the critical stability limit of multi-component β-Ti alloys with low Young's moduli, where the critical lower limit for β stabilization is (Moeq)Q = 6.25 at. pct or 11.8 wt pct Mo.

  5. ESTUDIO DE MEZCLA DE NANOPARTÍCULAS SULFURADAS Y OXIDADAS DE Mo Y DE Ni SOPORTADAS EN ALÚMINA, OBTENIDAS POR EL MÉTODO DE DESCOMPOSICIÓN TÉRMICA

    Directory of Open Access Journals (Sweden)

    Susana Martínez

    2011-01-01

    Full Text Available Se sintetizó una mezcla de nanopartículas sulfuradas y oxidadas de Mo y de Ni por el método de descomposición térmica, empleando un sistema de reflujo, dimetil disulfuro como agente sulfidizante, nonano como disolvente y una alúmina comercial que fungía como soporte. El sólido gris resultante se eliminó primero por decantación y luego por evaporación del líquido remanente bajo condiciones de vacío con el fin de evitar cambios, específicamente en las nanopartículas obtenidas. Una vez obtenidas las nanopartículas soportadas en alúmina se determinaron sus propiedades fisicoquímicas (morfología, estructura cristalina, estado de oxidación y composición elemental empleando las técnicas de HR-TEM, XPS e ICP. Los resultados de XPS y MET-HR muestran que el sólido esta conformado por nanopartículas de los metales seleccionados en sus formas oxidadas y sulfuradas tales como MoO3, MoS2, Ni2O3 y NiS, siendo la fase mayoritaria el MoO3. En los resultados no se evidenciaron fases mixtas o aleaciones de Mo y Ni.

  6. Nanoparticles of superconducting γ-Mo2N and δ-MoN

    International Nuclear Information System (INIS)

    Gomathi, A.; Sundaresan, A.; Rao, C.N.R.

    2007-01-01

    We have been able to prepare nanoparticles (∼4 nm diameter) of cubic γ-Mo 2 N by a simple procedure involving the reaction of MoCl 5 with urea at 873 K. The nanoparticles show a superconducting transition around 6.5 K. The γ-Mo 2 N nanoparticles are readily transformed to nanoparticles of δ-MoN with a slightly larger diameter on heating in a NH 3 atmosphere at 573 K. Phase-pure δ-MoN obtained by this means shows a superconducting transition around 5 K. - Graphical abstract: TEM image of the γ-Mo 2 N particles with the inset showing the resistivity of the sample as a function of temperature

  7. Microwave effects on NiMoS and CoMoS single-sheet catalysts.

    Science.gov (United States)

    Borges, I; Silva, Alexander M; Modesto-Costa, Lucas

    2018-05-04

    Single-sheet nanoclusters of MoS 2 , NiMoS or CoMoS are widely used in hydrodesulfurization (HDS) catalysis in the petroleum industry. In HDS reactions under microwave irradiation, experiments indirectly pointed out that for pristine MoS 2 reaction rates are accelerated because hot spots are generated on the catalyst bed. In this work, we investigated NiMoS and CoMoS isolated single-sheet substituted catalysts before and after thiophene adsorption focusing on quantifying the effect of microwave irradiation. For that purpose, density functional theory (DFT) molecular charge densities of each system were decomposed according to the distributed multipole analysis (DMA) of Stone. Site dipole values of each system were directly associated with a larger or smaller interaction with the microwave field according to a proposed general approach. We showed that microwave enhancement of HDS reaction rates can occur more efficiently in the CoMoS and NiMoS promoted clusters compared to pristine MoS 2 in the following order: CoMoS > NiMoS > MoS 2 . The atomic origin of the catalyst hot spots induced by microwaves was clearly established in the promoted clusters.

  8. Electronic structure of structural open derivatives of the [Mo6X14]2- cluster: [Mo5Cl13]2- and [Mo4I11]2-

    International Nuclear Information System (INIS)

    Miessner, H.; Korol'kov, D.V.

    1983-01-01

    The electronic structure of structural open derivatives of the [Mo 6 X 14 ] 2 - -cluster [Mo 5 Cl 13 ] 2 - and [Mo 4 I 11 ] 2 - has been studied by the EHMO method. In [Mo 5 Cl 13 ] 2 - 9 occupied MO's with dominant Mo4d character are responsible for the formation of the 8 metal-metal bonds. In [Mo 4 I 11 ] 2 - the stronger covalent character of the Mo-I bonds affects the localization and the energy of molecular orbitals and also the charge distribution. The metal-metal bonds are formed by 8 MO's containing considerable participation of halogen AO's contrary to the chloride cluster. There is no bonding between the Mo atoms at the wing tips of the Mo 4 butterfly and the reason for decreasing the dihedral angle between the Mo 3 planes in [Mo 4 I 11 ] 2 - compared with the octahedral angle is apparently the stabilization of the whole system (Mo-Mo and Mo-I bonds). The unpaired electron occupies in both clusters a slightly antibonding (with regard to the Mo-Mo bonds) orbital. (author)

  9. The Montreal Cognitive Assessment (MoCA) is superior to the Mini Mental State Examination (MMSE) in detection of Korsakoff's syndrome.

    Science.gov (United States)

    Oudman, Erik; Postma, Albert; Van der Stigchel, Stefan; Appelhof, Britt; Wijnia, Jan W; Nijboer, Tanja C W

    2014-01-01

    The Montreal Cognitive Assessment (MoCA) and Mini Mental State Examination (MMSE) are brief screening instruments for cognitive disorders. Although these instruments have frequently been used in the detection of dementia, there is currently little knowledge on the validity to detect Korsakoff's syndrome (KS) with both screening instruments. KS is a chronic neuropsychiatric disorder associated with profound declarative amnesia after thiamine deficiency. A representative sample of 30 patients with KS and 30 age-, education-, gender- and premorbid-IQ-matched controls was administered the MoCA and MMSE. The area under the receiver operating characteristic curve (AUC) was calculated in addition to the sensitivity, specificity, positive predictive value, and negative predictive value for various cut-off points on the MoCA and MMSE. Compared with the MMSE, the MoCA demonstrated consistently superior psychometric properties and discriminant validity--AUC: MoCA (1.00 SE .003) and MMSE (0.92 SE .033). When applying a cut-off value as suggested in the manuals of both instruments, the MMSE (< 24) misdiagnosed 46.7% of the patients, while the MoCA (< 26) diagnosed all patients correctly. As a screening instrument with the most optimal cut-offs, the MoCA (optimal cutoff point 22/23, 98.3% correctly diagnosed) was superior to the MMSE (optimal cutoff point 26/27, 83.3% correctly diagnosed). We conclude that both tests have adequate psychometric properties as a screening instrument for the detection of KS, but the MoCA is superior to the MMSE for this specific patient population.

  10. Comportamiento de variables químicas de un suelo sometido a distintos usos, departamento de Nariño, Colombia

    Directory of Open Access Journals (Sweden)

    Julio César Arteaga

    2016-12-01

    Full Text Available El presente estudio se realizó en un Andisol clasificado como Vitric haplustands, ubicado en el Corregimiento de Obonuco, Municipio de Pasto (Colombia. Se evaluaron algunas características químicas, en siete tipos de uso y manejo del suelo: T1: monocultivo de papa (Solanum tubersum L., T2: pradera (Pennisetum clandestinum Hochst. ex Chiov, T3: barrera multiestrato, T4: sistema acacia - aliso, T5: banco de proteína, T6: bosque plantado (Eucaliptus globulus Labill y T7: bosque nativo. El efecto de los tipos de uso y manejo, sobre las propiedades químicas del suelo, se evaluaron a través de pH, %MO, %CO, N total, P, CIC, Ca, Mg, K, Al, Fe, Mn Cu, Zn, B y S. Los resultados fueron sometidos a Análisis de Varianza, Prueba de Comparaciones de Medias (LSD, Diferencia Mínima Significativa (DMS y correlaciones de Persson. Los valores mostraron diferencias significativas (P<0,05 entre los tratamientos para los contenidos de pH, %MO, %CO, N total, P, CIC Ca, Mg, K, Fe y S, mientras que no se presentaron efectos sobre los contenidos de Al, Mn, B, Zn y Cu. Los mayores valores de %MO, %CO, N total, CIC, Ca, Mg y S, fueron obtenidos con los tratamientos T3, T4 y T7. Los resultados sugieren a la materia orgánica, como la variable más sensible al efecto del manejo de los suelos.

  11. GENERACIÓN TRAS GENERACIÓN, SE RECOBRAN LOS JUEGOS TRADICIONALES

    Directory of Open Access Journals (Sweden)

    María Morera Castro

    2008-07-01

    Full Text Available Actualmente, las comunidades, barrios y ambientes se encuentran inmersos en una serie de situaciones y problemáticas que han propiciado el deterioro de valores sociales, culturales y espirituales, indispensables para la armonía con uno mismo, el prójimo y el entorno. Los estereotipos se han apoderado de las mentes y los entornos se han reducido a cuatro paredes, llenos de rejas y dispositivos de seguridad. La paz, la fraternidad, y alegría se van, disminuyen. Y es aquí donde la labor social, espiritual y profesional de especialistas en el ámbito recreativo toma fuerza para contribuir con el rescate y la reestructuración de la sociedad. Son los juegos y las rondas tradicionales instrumentos que facilitan las relaciones, contribuyen en el aprendizaje y son una prueba de demostración de habilidades. Forman parte inseparable de la vida de la persona ya que estos son una expresión social y cultural de la adaptación que ha protagonizado el ser humano en relación con su entorno (Maestro, 2005. Además no toma en cuenta la raza, edad, sexo o la condición social; son una fuente generadora de salud, una ayuda para mejorar las destrezas motoras, cognitivas y emocionales; un medio para fomentar la creatividad, despertar la imaginación, desarrollar el sentido del ritmo; su objetivo es el bienestar personal. Son un estímulo para liberar tensiones y energía acumulada, así como para salir de la rutina diaria y un puente para el aprendizaje de sí mismo, del hábitat, de valores, costumbres y tradiciones. A través de este documento las personas podrán encontrar respuesta a cómo se trasmiten los juegos tradicionales, qué los caracteriza, por qué son una herramienta importante en la sociedad actual, con qué y cómo se pueden elaborar y de qué manera se puede contribuir al rescate y conservación de los mismos.

  12. Back surface studies of Cu(In,Ga)Se2 thin film solar cells

    Science.gov (United States)

    Simchi, Hamed

    Cu(In,Ga)Se2 thin film solar cells have attracted a lot of interest because they have shown the highest achieved efficiency (21%) among thin film photovoltaic materials, long-term stability, and straightforward optical bandgap engineering by changing relative amounts of present elements in the alloy. Still, there are several opportunities to further improve the performance of the Cu(In,Ga)Se2 devices. The interfaces between layers significantly affect the device performance, and knowledge of their chemical and electronic structures is essential in identifying performance limiting factors. The main goal of this research is to understand the characteristics of the Cu(In,Ga)Se2-back contact interface in order to design ohmic back contacts for Cu(In,Ga)Se2-based solar cells with a range of band gaps and device configurations. The focus is on developing either an opaque or transparent ohmic back contact via surface modification or introduction of buffer layers in the back surface. In this project, candidate back contact materials have been identified based on modeling of band alignments and surface chemical properties of the absorber layer and back contact. For the first time, MoO3 and WO 3 transparent back contacts were successfully developed for Cu(In,Ga)Se 2 solar cells. The structural, optical, and surface properties of MoO 3 and WO3 were optimized by controlling the oxygen partial pressure during reactive sputtering and post-deposition annealing. Valence band edge energies were also obtained by analysis of the XPS spectra and used to characterize the interface band offsets. As a result, it became possible to illuminate of the device from the back, resulting in a recently developed "backwall superstrate" device structure that outperforms conventional substrate Cu(In,Ga)Se2 devices in the absorber thickness range 0.1-0.5 microm. Further enhancements were achieved by introducing moderate amounts of Ag into the Cu(In,Ga)Se2 lattice during the co-evaporation method

  13. Didáctica de la literatura: ¿cómo se contagia la literatura?

    Directory of Open Access Journals (Sweden)

    Federico Altamirano Flores

    2016-01-01

    Full Text Available El artículo tiene como objetivo proponer una estrategia de contagio de la literatura para la intervención práctica en la educación literaria de los estudiantes. Se propone el modelado estético como una estrategia pertinente para transmitir la pasión por la literatura. La propuesta se sustenta en la teoría del contagio literario, la pedagogía dialogante y la estética general. La formulación de la estrategia se inspira, por un lado, en el modelado cognitivo de Bandura y, por el otro, en las experiencias pedagógicas del escritor Vladimir Nabokov, quien ejerció la educación literaria con mucho éxito. A partir del análisis de las clases y testimonios de Nabokov, se elabora el modelado estético con sus respectivos procedimientos didácticos. Esta estrategia puede ser una alternativa didáctica para educar la sensibilidad literaria de los estudiantes.

  14. Phase relations in the M2MoO4 - Ag2MoO4 - Hf(MoO4)2 (M=Li, Na) systems

    International Nuclear Information System (INIS)

    Bazarova, Zh.G.; Bazarov, B.G.; Balsanova, L.V.

    2002-01-01

    The M 2 MoO 4 - Ag 2 MoO 4 - Hf(MoO 4 ) 2 (M=Li, Na) systems were studied by X-ray diffraction and differential thermal analyses in the subsolidus area (450 - 500 Deg C) for the first time. The formation of the binary compound with the variable composition Li 4-x Hf 1+0.2x (MoO 4 ) 4 (0 ≤ x ≤ 0.6) in the Li 2 MoO 4 - Hf(MoO 4 ) 2 system and the ternary molybdates Li 4 Ag 2 Hf(MoO 4 ) 5 (S 1 ) and Na 2 Ag 2 Hf(MoO 4 ) 4 (S 2 ) was established and the thermal characteristics of the prepared compounds were examined. The new binary molybdate Ag 2 Hf(MoO 4 ) 3 was prepared by the reaction between Ag 2 MoO 4 and Hf(MoO 4 ) 2 [ru

  15. Phase formation in the Li2MoO4–K2MoO4–In2(MoO4)3 system and crystal structures of new compounds K3InMo4O15 and LiK2In(MoO4)3

    International Nuclear Information System (INIS)

    Khal’baeva, Klara M.; Solodovnikov, Sergey F.; Khaikina, Elena G.; Kadyrova, Yuliya M.; Solodovnikova, Zoya A.; Basovich, Olga M.

    2012-01-01

    XRD study of solid-phase interaction in the Li 2 MoO 4 –K 2 MoO 4 –In 2 (MoO 4 ) 3 system was performed. The boundary K 2 MoO 4 –In 2 (MoO 4 ) 3 system is an non-quasibinary join of the K 2 O–In 2 O 3 –MoO 3 system where a new polymolybdate K 3 InMo 4 O 15 isotypic to K 3 FeMo 4 O 15 was found. In the structure (a=33.2905(8), b=5.8610(1), c=15.8967(4) Å, β=90.725(1)°, sp. gr. C2/c, Z=8, R(F)=0.0407), InO 6 octahedra, Mo 2 O 7 diortho groups and MoO 4 tetrahedra form infinite ribbons {[In(MoO 4 ) 2 (Mo 2 O 7 )] 3− } ∞ along the b-axis. Between the chains, 8- to 10-coordinate potassium cations are located. A subsolidus phase diagram of the Li 2 MoO 4 –K 2 MoO 4 –In 2 (MoO 4 ) 3 system was constructed and a novel triple molybdate LiK 2 In(MoO 4 ) 3 was revealed. Its crystal structure (a=7.0087(2), b=9.2269(3), c=10.1289(3) Å, β=107.401(1)°, sp. gr. P2 1 , Z=2, R(F)=0.0280) contains an open framework of vertex-shared MoO 4 tetrahedra, InO 6 octahedra and LiO 5 tetragonal pyramids with nine- and seven-coordinate potassium ions in the framework channels. - Graphical abstract: Exploring the Li 2 MoO 4 –K 2 MoO 4 –In 2 (MoO 4 ) 3 system showed its partial non-quasibinarity and revealed new compounds K 3 InMo 4 O 15 (isotypic to K 3 FeMo 4 O 15 ) and LiK 2 In(MoO 4 ) 3 which were structurally studied. An open framework of the latter is formed by vertex-shared MoO 4 tetrahedra, InO 6 octahedra and LiO 5 tetragonal pyramids. Highlights: ► Subsolidus phase relations in the Li 2 MoO 4 –K 2 MoO 4 –In 2 (MoO 4 ) 3 system were explored. ► The K 2 MoO 4 –In 2 (MoO 4 ) 3 system is a non-quasibinary join of the K 2 O–In 2 O 3 –MoO 3 system. ► New compounds K 3 InMo 4 O 15 and LiK 2 In(MoO 4 ) 3 were obtained and structurally studied. ► K 3 InMo 4 O 15 is isotypic to K 3 FeMo 4 O 15 and carries bands of InO 6 , MoO 4 and Mo 2 O 7 units. ► An open framework of LiK 2 In(MoO 4 ) 3 is formed by polyhedra MoO 4 , InO 6 and LiO 5 .

  16. Mesa NTMS 10 x 20 quadrangle area. Supplemental data report

    International Nuclear Information System (INIS)

    Koller, G.R.

    1980-01-01

    This data report presents supplemental analytical results for stream sediments and ground water. The samples were collected as part of the SRL-NURE reconnaissance in the National Topographic Map Series (NTMS) Mesa 1 0 x 2 0 quadrnangle. Results are reported for 24 elements (Ag, As, Ba, Be, Ca, Co, Cr, Cu, K, Li, Mg, Mo, Nb, Ni, P, Pb, Se, Sn, Sr, Th, W, Y, Zn, and extractable U) in sediments and 31 elements (Ag, Al, As, B, Ba, Be, Ca, Ce, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Nb, Ni, P, Sc, Se, Si, Sr, Th, Ti, V, Y, Zn, and Zr) as well as pH, alkalinity, and conductivity in ground water

  17. Tempering of Mn and Mn-Si-V dual-phase steels

    Science.gov (United States)

    Speich, G. R.; Schwoeble, A. J.; Huffman, G. P.

    1983-06-01

    Changes in the yield behavior, strength, and ductility of a Mn and a Mn-Si-V d11Al-phase (ferrite-martensite) steel were investigated after tempering one hour at 200 to 600 °C. The change in yield behavior was complex in both steels with the yield strength first increasing and then decreasing as the tempering temperature was increased. This complex behavior is attributed to a combination of factors including carbon segregation to dislocations, a return of discontinuous yielding, and the relief of resid11Al stresses. In contrast, the tensile strength decreased continuously as the tempering temperature was increased in a manner that could be predicted from the change in hardness of the martensite phase using a simple composite strengthening model. The initial tensile ductility (total elongation) of the Mn-Si-V steel was much greater than that of the Mn steel. However, upon tempering up to 400 °C, the ductility of the Mn-Si-V decreased whereas that of the Mn steel increased. As a result, both steels had similar ductilities after tempering at 400 °C or higher temperatures. These results are attributed to the larger amounts of retained austenite in the Mn-Si-V steel (9 pct) compared to the Mn steel (3 pct) and its contribution to tensile ductility by transforming to martensite during plastic straining. Upon tempering at 400 °C, the retained austenite decomposes to bainite and its contribution to tensile ductility is eliminated.

  18. ITO-free flexible organic photovoltaics with multilayer MoO3/LiF/MoO3/Ag/MoO3 as the transparent electrode

    International Nuclear Information System (INIS)

    Chen, Shilin; Dai, Yunjie; Zhang, Hongmei; Zhao, Dewei

    2016-01-01

    We present efficient flexible organic photovoltaics (OPVs) with multiple layers of molybdenum oxide (MoO 3 )/LiF/MoO 3 /Ag/MoO 3 as the transparent electrode, where the thin Ag layer yields high conductivity and the dielectric layer MoO 3 /LiF/MoO 3 has high transparency due to optical interference, leading to improved power conversion efficiency compared with indium tin oxide (ITO) based devices. The MoO 3 contacting organic active layer is used as a buffer layer for good hole extraction. Thus, the multilayer MoO 3 /LiF/MoO 3 /Ag/MoO 3 can improve light transmittance and also facilitate charge carrier extraction. Such an electrode shows excellent mechanical bendability with a 9% reduction of efficiency after 1000 cycles of bending due to the ductile nature of the thin metal layer and dielectric layer used. Our results suggest that the MoO 3 /LiF/MoO 3 /Ag/MoO 3 multilayer electrode is a promising alternative to ITO as an electrode in OPVs. (paper)

  19. Valence state of Mn in Ca-doped LaMnO3 studied by high-resolution Mn K ß emission spectroscopy

    NARCIS (Netherlands)

    Tyson, T.A.; Qian, Q.; Kao, C.-C.; Rueff, J.-P.; Groot, F.M.F. de; Croft, M.; Cheong, S.-W.; Greenblatt, M.; Subramanian, M.A.

    1999-01-01

    Mn K ß x-ray emission spectra provide a direct method to probe the effective spin state and charge density on the Mn atom and is used in an experimental study of a class of Mn oxides. Specifically, the Mn K ß line positions and detailed spectral shapes depend on the oxidation and the spin state of

  20. Tunable redox potential of nonmetal doped monolayer MoS{sub 2}: First principle calculations

    Energy Technology Data Exchange (ETDEWEB)

    Lu, S. [Center for Coordination Bond Engineering, China Jiliang University (China); Li, C., E-mail: canli1983@gmail.com [Center for Coordination Bond Engineering, China Jiliang University (China); School of Materials Science and Engineering, China Jiliang University (China); Zhao, Y.F.; Gong, Y.Y.; Niu, L.Y.; Liu, X.J. [Center for Coordination Bond Engineering, China Jiliang University (China)

    2016-10-30

    Graphical abstract: Both E{sub CBM} and E{sub VBM} values are affected by the chemical valences of dopants, which also affect the redox potentials of specimens. Compared to the pristine monolayer MoS{sub 2}, the nonmetal ions with odd chemical valences [monovalent (H{sup +}, F{sup –}, Cl{sup –}, Br{sup –} and I{sup –}), trivalent (N{sup 3–}, P{sup 3–} and As{sup 3–}) and pentavalence (B{sup 5–})] enhance the oxidation potential and reduce the reduction potential of specimens, but the nonmetal ions with even chemical valences [divalent (O{sup 2–}, Se{sup 2–} and Te{sup 2–}) and quadravalent (C{sup 4–} and Si{sup 4–})] have the opposite effects on the redox potentials. Display Omitted - Highlights: • The newly formed chemical bonds affect the electronic distribution around the dopants and the nearby Mo atoms. • Compared to pristine monolayer MoS{sub 2}, the nonmetal ions with odd (even) chemical valences enhance (reduce) the oxidation potential and reduce (enhance) the reduction potential of specimens. • The lone pair electrons in nonmetal ions with odd chemical valences extra interact with the Mo ions which reduces the E{sub CBM} and E{sub VBM} values of specimens. - Abstract: Doping is an effective method to alter the electronic behavior of materials by forming new chemical bonds and bringing bond relaxation. With this aid of first principle calculations, the crystal configuration and electronic properties of monolayer MoS{sub 2} have been modulated by the nonmetal (NM) dopants (H, B, C, N, O, F, Si, P, Cl, As, Se, Br, Te and I), and the thermodynamic stability depending on the preparation conditions (Mo-rich and S-rich conditions) were discussed. Results shown that, the NM dopants substituted preferentially for S under Mo-rich condition, the electronic distribution around the dopants and the nearby Mo atoms are changed by the new formed Mo-NM bonds and bands relaxation. Compared to pristine monolayer MoS{sub 2}, the NM ions with odd

  1. Macro and Trace Element Accumulation in Edible Crabs and Frogs ...

    African Journals Online (AJOL)

    The tissue accumulation of five macroelements (Na, Mg, K, Ca, Fe) and twelve trace elements (Vd, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, Pb) were assessed in the organs of the edible frogs; Xenopus laevis and Rana esculentus, and whole body of the crab, Callinestes caught from Alaro Stream Floodplain (Ibadan, ...

  2. Determination of As, Cr, Mo, Sb, Se and V in agricultural soil samples by inductively coupled plasma optical emission spectrometry after simple and rapid solvent extraction using choline chloride-oxalic acid deep eutectic solvent.

    Science.gov (United States)

    Matong, Joseph M; Nyaba, Luthando; Nomngongo, Philiswa N

    2017-01-01

    A rapid, simple and green ultrasound-assisted extraction method using deep eutectic solvents (DES) for extraction of As, Cr, Mo, Sb, Se and V in soil samples, has been developed. Choline chloride-oxalic acid based DES was used as a solvent. The target analytes were subsequently quantified using inductively coupled plasma optical emission spectrometer (ICP OES). The parameters that affect the extraction of the target analytes was optimized using standard reference material of San Joaquin soil (SRM 2709a). In the optimization step, a two-level full factorial experimental design was used. The factors under investigation include extraction time, sample mass and acid concentration. Under optimized conditions, limits of detection (LOD) and limits of quantification (LOQ) ranged from 0.009 to 0.1 and 0.03-0.3µgg -1 , respectively. The repeatability (n=20) estimated in terms of relative standard deviation (%RSD) ranged from 0.9% to 3.7%. The accuracy of the proposed method was carried out using SRM 2709a. The obtained and certified/ indicative values were statistically in good agreement at 95% confidence level. The proposed method applied for quantification of As, Cr, Mo, Sb, Se and V in real soil samples. For comparison, the analytes of interest were also determined using a conventional acid digestion method. According to the paired t-test, the analytical results were not significant differences at 95% confidence level. The method was found to be accurate, precise and environmentally friendly. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Strong correlation and ferromagnetism in (Ga,Mn)As and (Ga,Mn)N

    International Nuclear Information System (INIS)

    Filippetti, A.; Spaldin, N.A.; Sanvito, S.

    2005-01-01

    The band energies of the ferromagnetic diluted magnetic semiconductors (Ga,Mn)As and (Ga,Mn)N are calculated using a self-interaction-free approach which describes covalent and strongly correlated electrons without adjustable parameters. Both materials are half-metallic, although the contribution of Mn-derived d states to the bands around the Fermi energy is very different in the two cases. In (Ga,Mn)As the bands are strongly p-d hybridized, with a dominance of As p states. In contrast in (Ga,Mn)N the Fermi energy lies within three flat bands of mainly d character that are occupied by two electrons. Thus the Mn ion in (Ga,Mn)N behaves as a deep trap acceptor, with the hole at 1.39 eV above the GaN valence band top, and is in excellent agreement with the experimental data

  4. Thermal expansion studies on Th(MoO4)2, Na2Th(MoO4)3 and Na4Th(MoO4)4

    International Nuclear Information System (INIS)

    Keskar, Meera; Krishnan, K.; Dahale, N.D.

    2008-01-01

    Thermal expansion behavior of Th(MoO 4 ) 2 , Na 2 Th(MoO 4 ) 3 and Na 4 Th(MoO 4 ) 4 was studied under vacuum in the temperature range of 298-1123 K by high temperature X-ray diffractometer. Th(MoO 4 ) 2 was synthesized by reacting ThO 2 with 2 mol of MoO 3 , at 1073 K in air and Na 2 Th(MoO 4 ) 3 and Na 4 Th(MoO 4 ) 4 were prepared by reacting Th(MoO 4 ) 2 with 1 and 2 mol of Na 2 MoO 4 , respectively at 873 K in air. The XRD data of Th(MoO 4 ) 2 was indexed on orthorhombic system where as XRD data of Na 2 Th(MoO 4 ) 3 and Na 4 Th(MoO 4 ) 4 were indexed on tetragonal system. The lattice parameters and cell volume of all the three compounds, fit into polynomial expression with respect to temperature, showed positive thermal expansion (PTE) up to 1123 K. The average value of thermal expansion coefficients for Th(MoO 4 ) 2 , Na 2 Th(MoO 4 ) 3 and Na 4 Th(MoO 4 ) 4 were determined from the high temperature data

  5. Mechanical properties of steel 8 CrMoNiNb 9 10 in dependence on the microstructural condition

    International Nuclear Information System (INIS)

    Fabritius, H.; Schnabel, E.

    1976-01-01

    Tension tests at room temperature to 600 0 C and creep-rupture tests at 500 to 600 0 C lasting up to about 75,000 h on two casts of steel 8 CrMoNiNb 9 10 with about 0.08% C, 0.3% Si, 0.7% Mn, 0.012% N, 0.005% Al, 2.34% Cr, 0.95% Mo, 0.8% Nb and 0.64% Ni in bainitic and ferritic microstructural condition. Influence of annealing at 650 to 800 0 C on the properties in the tension test. Influence of aging at 500 to 600 0 C lasting up to 30,000 h with and without mechanical stress on the properties in the tension test at aging temperature and on the toughness behaviour in the notched bar impact bend test at room temperature. (orig.) [de

  6. Effect of Mn and Fe on the Formation of Fe- and Mn-Rich Intermetallics in Al–5Mg–Mn Alloys Solidified Under Near-Rapid Cooling

    Directory of Open Access Journals (Sweden)

    Yulin Liu

    2016-01-01

    Full Text Available Mn was an important alloying element used in Al–Mg–Mn alloys. However, it had to be limited to a low level (<1.0 wt % to avoid the formation of coarse intermetallics. In order to take full advantage of the benefits of Mn, research was carried out to investigate the possibility of increasing the content of Mn by studying the effect of cooling rate on the formation of Fe- and Mn-rich intermetallics at different content levels of Mn and Fe. The results indicated that in Al–5Mg–Mn alloy with low Fe content (<0.1 wt %, intermetallic Al6(Fe,Mn was small in size and amount. With increasing Mn content, intermetallic Al6(Fe,Mn increased, but in limited amount. In high-Fe-containing Al–5Mg–Mn alloys (0.5 wt % Fe, intermetallic Al6(Fe,Mn became the dominant phase, even in the alloy with low Mn content (0.39 wt %. Cooling rate played a critical role in the refinement of the intermetallics. Under near-rapid cooling, intermetallic Al6(Fe,Mn was extremely refined. Even in the high Mn and/or high-Fe-containing alloys, it still demonstrated fine Chinese script structures. However, once the alloy composition passed beyond the eutectic point, the primary intermetallic Al6(Fe,Mn phase displayed extremely coarse platelet-like morphology. Increasing the content of Fe caused intermetallic Al6(Fe,Mn to become the primary phase at a lower Mn content.

  7. Effect of Mn and Fe on the Formation of Fe- and Mn-Rich Intermetallics in Al–5Mg–Mn Alloys Solidified Under Near-Rapid Cooling

    Science.gov (United States)

    Liu, Yulin; Huang, Gaoren; Sun, Yimeng; Zhang, Li; Huang, Zhenwei; Wang, Jijie; Liu, Chunzhong

    2016-01-01

    Mn was an important alloying element used in Al–Mg–Mn alloys. However, it had to be limited to a low level (Al–5Mg–Mn alloy with low Fe content (Al6(Fe,Mn) was small in size and amount. With increasing Mn content, intermetallic Al6(Fe,Mn) increased, but in limited amount. In high-Fe-containing Al–5Mg–Mn alloys (0.5 wt % Fe), intermetallic Al6(Fe,Mn) became the dominant phase, even in the alloy with low Mn content (0.39 wt %). Cooling rate played a critical role in the refinement of the intermetallics. Under near-rapid cooling, intermetallic Al6(Fe,Mn) was extremely refined. Even in the high Mn and/or high-Fe-containing alloys, it still demonstrated fine Chinese script structures. However, once the alloy composition passed beyond the eutectic point, the primary intermetallic Al6(Fe,Mn) phase displayed extremely coarse platelet-like morphology. Increasing the content of Fe caused intermetallic Al6(Fe,Mn) to become the primary phase at a lower Mn content. PMID:28787888

  8. Effect of Mn and Fe on the Formation of Fe- and Mn-Rich Intermetallics in Al-5Mg-Mn Alloys Solidified Under Near-Rapid Cooling.

    Science.gov (United States)

    Liu, Yulin; Huang, Gaoren; Sun, Yimeng; Zhang, Li; Huang, Zhenwei; Wang, Jijie; Liu, Chunzhong

    2016-01-29

    Mn was an important alloying element used in Al-Mg-Mn alloys. However, it had to be limited to a low level (Al-5Mg-Mn alloy with low Fe content (Al₆(Fe,Mn) was small in size and amount. With increasing Mn content, intermetallic Al₆(Fe,Mn) increased, but in limited amount. In high-Fe-containing Al-5Mg-Mn alloys (0.5 wt % Fe), intermetallic Al₆(Fe,Mn) became the dominant phase, even in the alloy with low Mn content (0.39 wt %). Cooling rate played a critical role in the refinement of the intermetallics. Under near-rapid cooling, intermetallic Al₆(Fe,Mn) was extremely refined. Even in the high Mn and/or high-Fe-containing alloys, it still demonstrated fine Chinese script structures. However, once the alloy composition passed beyond the eutectic point, the primary intermetallic Al₆(Fe,Mn) phase displayed extremely coarse platelet-like morphology. Increasing the content of Fe caused intermetallic Al₆(Fe,Mn) to become the primary phase at a lower Mn content.

  9. ¿Cómo evaluar si se «hace» ciencia en el aula?

    OpenAIRE

    Gil Pérez, Daniel; Martínez-Torregrosa, Joaquín

    1999-01-01

    Hacer ciencia en el aula puede parecer algo "natural" en la educación científica. Sin embargo, la investigación ha mostrado que, tras esta pretensión de hacer ciencia, subyacen, a menudo, concepciones de lo que constituye el trabajo científico que incurren en graves reduccionismos y deformaciones. El objetivo principal de este artículo es, precisamente, detenerse en clarificar los criterios que permitan distinguir si se está facilitando el trabajo científico o se está promoviendo una imagen d...

  10. Large magnetization and frustration switching of magnetoresistance in the double-perovskite ferrimagnet Mn2FeReO6.

    Science.gov (United States)

    Arévalo-López, Angel M; McNally, Graham M; Attfield, J Paul

    2015-10-05

    Ferrimagnetic A2 BB'O6 double perovskites, such as Sr2 FeMoO6 , are important spin-polarized conductors. Introducing transition metals at the A-sites offers new possibilities to increase magnetization and tune magnetoresistance. Herein we report a ferrimagnetic double perovskite, Mn2 FeReO6 , synthesized at high pressure which has a high Curie temperature of 520 K and magnetizations of up to 5.0 μB which greatly exceed those for other double perovskite ferrimagnets. A novel switching transition is discovered at 75 K where magnetoresistance changes from conventional negative tunneling behavior to large positive values, up to 265 % at 7 T and 20 K. Neutron diffraction shows that the switch is driven by magnetic frustration from antiferromagnetic Mn(2+) spin ordering which cants Fe(3+) and Re(5+) spins and reduces spin-polarization. Ferrimagnetic double perovskites based on A-site Mn(2+) thus offer new opportunities to enhance magnetization and control magnetoresistance in spintronic materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Measurement of the <mn>3mn>s>1mn>/>2mn>->3mn>p>3mn>/>2mn> resonance line of sodiumlike Eu<mn>52mn>+>

    Energy Technology Data Exchange (ETDEWEB)

    Träbert, E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Beiersdorfer, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hell, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of Erlangen-Nuremberg (Germany); Brown, G. V. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-08-01

    We have measured the 3 s 1 / 2 - 3 p 3 / 2 transition in sodiumlike Eu 52 + situated at 41.232 Å with an uncertainty of 73 ppm. Our measurement extends previous high-precision measurements into the 56 < Z < 78 range of atomic numbers. We also present measurements of 3 s 1 / 2 - 3 p 3 / 2 and 3 p 1 / 2 - 3 d 3 / 2 transitions in the neighboring magnesiumlike, aluminumlike, and siliconlike europium ions.

  12. Impact of sodium on the secondary phases and current pathway in Cu{sub 2}(Zn,Sn)Se{sub 4} thin film solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yi-Cheng, E-mail: ielinyc@cc.ncue.edu.tw [Department of Mechatronics Engineering, National Changhua University of Education, Changhua, Taiwan (China); Lai, Chien-Mu [Department of Mechatronics Engineering, National Changhua University of Education, Changhua, Taiwan (China); Hsu, Hung-Ru [Green Energy & Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China)

    2017-05-01

    In this study, we investigated the influence of Na content on secondary phases and current pathway in Cu{sub 2}(Zn,Sn)Se{sub 4} (CZTSe) thin film solar cells with the following structure: Ti/Mo:Na/Mo/CZTSe/CdS/i-ZnO/ZnO:Al/Al. The application of Na-doped Mo target as a source of sodium. Experimental results demonstrate that increasing the Na content leads to an increase in the quantity of secondary phase SnSe{sub 2} on the surface of the absorber layer; however, it did not appear to affect the secondary phases of Cu{sub 2}SnSe{sub 3} (CTSe) or ZnSe. Excessive quantities of Na were shown to have an adverse effect on device efficiency. Our results using conductive atomic force microscopy (C-AFM) revealed that an increase in the quantity of secondary phase SnSe{sub 2} can shift the current pathway on the surface of CZTSe from CZTSe grain boundaries (GBs) to the SnSe{sub 2} grains. The role of secondary phase SnSe{sub 2} of the CZTSe acted as a channel for the current flow, which results in high leakage current and low device efficiency. - Highlights: • Increasing the Na content leads to an increase in the quantity of secondary phase SnSe{sub 2}. • An increase of secondary phase SnSe{sub 2} can shift the current pathway from CZTSe grain boundaries to the SnSe{sub 2} grains. • The secondary phase SnSe{sub 2} acted as a channel for the current flow, which results in high leakage current.

  13. Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

    Energy Technology Data Exchange (ETDEWEB)

    Cui, J., E-mail: jun.cui@pnnl.gov; Choi, J. P.; Li, G.; Polikarpov, E.; Darsell, J. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354 (United States); Kramer, M. J.; Zarkevich, N. A.; Wang, L. L.; Johnson, D. D. [Materials Sciences and Engineering Division, Ames Laboratory, Ames, Iowa 50011 (United States); Marinescu, M. [Electron Energy Corporation, Landisville, Pennsylvania 17538 (United States); Huang, Q. Z.; Wu, H. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102 (United States); Vuong, N. V.; Liu, J. P. [Department of Physics, University of Texas at Arlington, Arlington, Texas 76019 (United States)

    2014-05-07

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 μ{sub B} at 50 K and 300 K, respectively.

  14. Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

    Energy Technology Data Exchange (ETDEWEB)

    Cui, J; Choi, JP; Li, G; Polikarpov, E; Darsell, J; Kramer, MJ; Zarkevich, NA; Wang, LL; Johnson, DD; Marinescu, M; Huang, QZ; Wu, H; Vuong, NV; Liu, JP

    2014-05-07

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 mu(B) at 50 K and 300 K, respectively. (C) 2014 AIP Publishing LLC.

  15. Ternary system of Na2MoO4-Cs2MoO4-MoO3

    International Nuclear Information System (INIS)

    Zueva, V.P.; Shabanova, A.N.; Drobasheva, T.I.

    1982-01-01

    Using the methods of thermal analysis interaction of components in ternary system Na 2 MoO 4 -Cs 2 MoO 4 -MoO 3 has been studied. Crystallization surface consists of nine fields belonging to initial components and compounds of lateral sides. Triangulation of the system is carried out and the character of nonvariant points is clarified, the temperature of 360 deg C corresponds to low-melting eutectics

  16. Hydrothermal Fe-Si-Mn oxide deposits from the Central and South Valu Fa Ridge, Lau Basin

    International Nuclear Information System (INIS)

    Sun Zhilei; Zhou Huaiyang; Yang Qunhui; Sun Zhixue; Bao Shenxu; Yao Huiqiang

    2011-01-01

    Highlights: → The Fe-Mn crust in the HHF has seawater contribution, whereas the Fe-Si oxide in the MHF is dominated by hydrothermal fluid → The Nd isotope of diffuse flow Fe-Si-Mn deposits indicates the obvious hydrothermal origin. → The Mn/Fe ratio in hydrothermal deposit may be a good indicator of propagating activities of the Valu Fa Ridge. - Abstract: A series of samples from the Hine Hina hydrothermal field (HHF) and the Mariner hydrothermal field (MHF) in the Central and Southern Valu Fa Ridge (VFR), Lau Basin were examined to explain the source origin and formation of the hydrothermal Fe-Si-Mn oxide deposits. The mineralogy was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Moessbauer spectroscopy, and energy-dispersive spectroscopy (EDS). For the Fe-Mn oxide crusts in the HHF, varying amounts of volcanic fragments and some seawater contributions were recognized, along with higher concentrations of Mn, Al, Co, Ni, Zn, Sr, Mo, elevated ΣREE and negative Ce anomalies. In contrast, the Si-rich oxide samples of the MHF were enriched in Cu, Pb and Ba, indicative of proximity to a hydrothermal jet. Moreover, conductive cooling of hydrothermal fluid evoked the Si-rich deposit formation in the MHF. The Sr, Nd and Pb isotope data provided further constraints regarding the source and formation of the Fe-Si-Mn deposits in the VFR by showing that the samples of the HHF are a mixture of three components, namely, hydrothermal fluid, seawater and volcanic materials, whereas the samples of the MHF were dominated by hydrothermal fluids. The seawater had a minor influence on the Nd isotope data, and the Pb isotope data exhibited a close association with the substrate rock and preformed volcaniclastic layers in this area. The occurrence of relatively high Mn/Fe ratios in the hydrothermal deposits of this area may be a good indicator of the propagating activities of the VFR over geological time.

  17. La pelota no se mancha: Un estudio histórico sobre el desarrollo y la política en FIFA

    OpenAIRE

    Susa Sánchez, David Esteban

    2015-01-01

    Esta investigación se centra en la Fédération Internationale de Football Association (FIFA) como organización política. Intenta responder dos interrogantes primordiales: 1) ¿cómo la FIFA ha constituido el poder que tiene actualmente y, así, hacerse del monopolio indiscutido del fútbol? Y 2) ¿cómo ha cambiado en el tiempo la política interna de FIFA y su vínculo con la política internacional? Para lograr esto, se realiza un estudio histórico, basado principalmente en documentos, que intenta ca...

  18. Mn(II,III) oxidation and MnO2 mineralization by an expressed bacterial multicopper oxidase

    Science.gov (United States)

    Butterfield, Cristina N.; Soldatova, Alexandra V.; Lee, Sung-Woo; Spiro, Thomas G.; Tebo, Bradley M.

    2013-01-01

    Reactive Mn(IV) oxide minerals are ubiquitous in the environment and control the bioavailability and distribution of many toxic and essential elements and organic compounds. Their formation is thought to be dependent on microbial enzymes, because spontaneous Mn(II) to Mn(IV) oxidation is slow. Several species of marine Bacillus spores oxidize Mn(II) on their exosporium, the outermost layer of the spore, encrusting them with Mn(IV) oxides. Molecular studies have identified the mnx (Mn oxidation) genes, including mnxG, encoding a putative multicopper oxidase (MCO), as responsible for this two-electron oxidation, a surprising finding because MCOs only catalyze single-electron transfer reactions. Characterization of the enzymatic mechanism has been hindered by the lack of purified protein. By purifying active protein from the mnxDEFG expression construct, we found that the resulting enzyme is a blue (absorption maximum 590 nm) complex containing MnxE, MnxF, and MnxG proteins. Further, by analyzing the Mn(II)- and (III)-oxidizing activity in the presence of a Mn(III) chelator, pyrophosphate, we found that the complex facilitates both electron transfers from Mn(II) to Mn(III) and from Mn(III) to Mn(IV). X-ray absorption spectroscopy of the Mn mineral product confirmed its similarity to Mn(IV) oxides generated by whole spores. Our results demonstrate that Mn oxidation from soluble Mn(II) to Mn(IV) oxides is a two-step reaction catalyzed by an MCO-containing complex. With the purification of active Mn oxidase, we will be able to uncover its mechanism, broadening our understanding of Mn mineral formation and the bioinorganic capabilities of MCOs. PMID:23818588

  19. Mossbauer and XRD characterization of the phase transformations in a Fe-Mn-Al-C-Mo-Si-Cu as cast alloy during tribology test

    Science.gov (United States)

    Ramos, J.; Piamba, J. F.; Sánchez, H.; Alcazar, G. A. Pérez

    2015-06-01

    In present study Fe-29.0Mn-6Al-0.9C-1.8Mo-1.6Si-0.4Cu (%w) alloy was obtained after melted in an induction furnace, and then molded as an ingot. From the as cast ingot it were cut samples for the different characterization measurements. The microstructure of the as-cast sample is of dendritic type and its XRD pattern was refined with the lines of the austenite, with a big volumetric fraction, and the lines of the martensite, with small volumetric fraction. The Mössbauer spectrum of the sample was fitted with a broad singlet which corresponds to disordered austenite. After the tribology test, its XRD pattern was refined with the lines of two austenite phases, one similar to the previous one and other with bigger lattice parameter. The total volumetric fraction of the austenite is smaller than that obtained for sample without wear. It was added the lines of the martensite phase with bigger volumetric fraction than that of the previous sample. The Mössbauer spectrum of the weared sample was fitted with two paramagnetic sites which correspond to the two Fe austenite phases and a hyperfine magnetic field distribution which is associated to the disordered original martensite and the new one which appears in the surface as a consequence of the wear process. These results show that during wear process the original austenite phase is transformed in martensite and in a new austenite phase. The increases of the martensitic phase improves mechanical properties and wear behavior.

  20. Mossbauer and XRD characterization of the phase transformations in a Fe-Mn-Al-C-Mo-Si-Cu as cast alloy during tribology test

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, J. [Universidad Autónoma de Occidente (Colombia); Piamba, J. F. [Universidad del Valle, Departamento Física (Colombia); Sánchez, H. [Universidad del Valle, Escuela de Materiales (Colombia); Alcazar, G. A. Pérez, E-mail: gpgeperez@gmail.com [Universidad del Valle, Departamento Física (Colombia)

    2015-06-15

    In present study Fe-29.0Mn-6Al–0.9C-1.8Mo-1.6Si-0.4Cu (%w) alloy was obtained after melted in an induction furnace, and then molded as an ingot. From the as cast ingot it were cut samples for the different characterization measurements. The microstructure of the as-cast sample is of dendritic type and its XRD pattern was refined with the lines of the austenite, with a big volumetric fraction, and the lines of the martensite, with small volumetric fraction. The Mössbauer spectrum of the sample was fitted with a broad singlet which corresponds to disordered austenite. After the tribology test, its XRD pattern was refined with the lines of two austenite phases, one similar to the previous one and other with bigger lattice parameter. The total volumetric fraction of the austenite is smaller than that obtained for sample without wear. It was added the lines of the martensite phase with bigger volumetric fraction than that of the previous sample. The Mössbauer spectrum of the weared sample was fitted with two paramagnetic sites which correspond to the two Fe austenite phases and a hyperfine magnetic field distribution which is associated to the disordered original martensite and the new one which appears in the surface as a consequence of the wear process. These results show that during wear process the original austenite phase is transformed in martensite and in a new austenite phase. The increases of the martensitic phase improves mechanical properties and wear behavior.