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Sample records for br cu fe

  1. Study of Br, Zn, Cu and Fe concentrations in healthy and cancer breast tissues by TXRF

    Science.gov (United States)

    Magalhães, T.; Becker, M.; Carvalho, M. L.; von Bohlen, A.

    2008-12-01

    Tissue samples of fifteen breasts were analyzed by X-ray fluorescence spectrometry in order to compare the elemental concentration in healthy and carcinoma regions of the same individual. Five women were from Germany and ten from Portugal living in big cities. The elemental distribution of P, S, K, Ca, Fe, Ni, Zn, Cu and Br present in both normal and cancerous breast tissues were studied. Several contiguous thin sections (up to 10 μm thickness) of each tissue were analyzed by TXRF in order to study the homogeneity in the elemental concentration along each tissue. Correlations between elemental concentrations were established. The main goal of this study was to demonstrate the presence of Br which is assumed to play an important role in breast carcinoma development. A similar pattern for almost all the analyzed tissues was obtained: levels of P, S, K, Ca, Fe, Cu, Zn and Br increased in carcinoma tissues when compared with the corresponding healthy ones. Contrarily to the findings of this study, those of early studies showed decreased Br levels for different carcinoma tissues, unlike to most other heavy elements.

  2. Magnetically separable CuFe{sub 2}O{sub 4}/AgBr composite photocatalysts: Preparation, characterization, photocatalytic activity and photocatalytic mechanism under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yalei; Lin, Cuiping; Bi, Huijie; Liu, Yonggang; Yan, Qishe, E-mail: Qisheyanzzu@163.com

    2017-01-15

    Highlights: • CuFe{sub 2}O{sub 4}/AgBr composites were prepared by a facile sol-gel and hydrothermal method. • Visible-light response and high photocatalytic performance. • Excellent magnetic properties. • Different reactive species had different effects on degradation different pollutants. - Abstract: The CuFe{sub 2}O{sub 4} and CuFe{sub 2}O{sub 4}/AgBr composites with different CuFe{sub 2}O{sub 4} contents were prepared by a facile sol-gel and hydrothermal method, respectively. The as-synthesized photocatalysts were characterized by means of powder X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectrum (UV–vis DRS). Their magnetic properties, photocatalytic degradation activities on methyl orange (MO) and tetracycline hydrochloride (TC) solution and photocatalytic mechanism were investigated in detail. The results revealed that the CuFe{sub 2}O{sub 4}/AgBr composites exhibited significantly higher photocatalytic activities than the pure CuFe{sub 2}O{sub 4}. The enhanced photocatalytic activity could be attributed to the matched band structure of two components and more effective charge transportation and separations. In addition, the quenching investigation of different scavengers demonstrated that h{sup +}, ·OH, ·O{sub 2}{sup −} reactive species played different roles in the decolorization of MO and degradation of TC.

  3. The association between content of the elements S, Cl, K, Fe, Cu, Zn and Br in normal and cirrhotic liver tissue from Danes and Greenlandic Inuit examined by dual hierarchical clustering analysis

    DEFF Research Database (Denmark)

    Laursen, Jens; Milman, Nils; Pind, N.

    2014-01-01

    PROJECT: Meta-analysis of previous studies evaluating associations between content of elements sulphur (S), chlorine (Cl), potassium (K), iron (Fe), copper (Cu), zinc (Zn) and bromine (Br) in normal and cirrhotic autopsy liver tissue samples. PROCEDURE: Normal liver samples from 45 Greenlandic......, Br and Zn; Cl with S and Br; K with S, Br and Zn; Cu with Br. Zn with S and K. Br with S, Cl, K and Cu. Fe did not show significant associations with any other element. CONCLUSIONS: In contrast to simple statistical methods, which analyses content of elements separately one by one, dual hierarchical...

  4. Dinuclear Metallacycles with Single M-X-M Bridges (X = Cl-, Br-; M = Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II)): Strong Antiferromagnetic Superexchange Interactions.

    Science.gov (United States)

    Reger, Daniel L; Pascui, Andrea E; Foley, Elizabeth A; Smith, Mark D; Jezierska, Julia; Wojciechowska, Agnieszka; Stoian, Sebastian A; Ozarowski, Andrew

    2017-03-06

    A series of monochloride-bridged, dinuclear metallacycles of the general formula [M2(μ-Cl)(μ-L)2](ClO4)3 have been prepared using the third-generation, ditopic bis(pyrazolyl)methane ligands L = m-bis[bis(1-pyrazolyl)methyl]benzene (Lm), M = Cu(II), Zn(II), and L = m-bis[bis(3,5-dimethyl-1-pyrazolyl)methyl]benzene (Lm*), M = Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II). These complexes were synthesized from the direct reactions of M(ClO4)2·6H2O, MCl2, and the ligand, Lm or Lm*, in the appropriate stoichiometric amounts. Three analogous complexes of the formula [M2(μ-Cl)(μ-L)2](BF4)3, L = Lm, M = Cu(II), and L = Lm*, M = Co(II), Cu(II), were prepared from the reaction of [M2(μ-F)(μ-L)2](BF4)3 and (CH3)3SiCl. The bromide-bridged complex [Cu2(μ-Br)(μ-Lm*)2](ClO4)3 was prepared by the first method. Three acyclic complexes, [Co2(μ-Lm)μ-Cl4], [Co2(μ-Lm*)Cl4], and [Co2(μ-Lm*)Br4], were also prepared. The structures of all [M2(μ-X)(μ-L)2]3+ (X = Cl-, Br-) complexes have two ditopic bis(pyrazolyl)methane ligands bridging two metals in a metallacyclic arrangement. The fifth coordination site of the distorted trigonal bipyramidal metal centers is filled by a bridging halide ligand that has an unusual linear or nearly linear M-X-M angle. The NMR spectra of [Zn2(μ-Cl)(μ-Lm*)2](ClO4)3 and especially [Cd2(μ-Cl)(μ-Lm*)2](ClO4)3 demonstrate that the metallacycle structure is maintained in solution. Solid state magnetic susceptibility data for the copper(II) compounds show very strong antiferromagnetic exchange interactions, with -J values of 536 cm-1 for [Cu2(μ-Cl)(μ-Lm)2](ClO4)3·xCH3CN, 720 cm-1 for [Cu2(μ-Cl)(μ-Lm*)2](ClO4)3, and 945 cm-1 for [Cu2(μ-Br)(μ-Lm*)2](ClO4)3·2CH3CN. Smaller but still substantial antiferromagnetic interactions are observed with other first row transition metals, with -J values of 98 cm-1 for [Ni2(μ-Cl)(μ-Lm*)2](ClO4)3, 55 cm-1 for [Co2(μ-Cl)(μ-Lm*)2](ClO4)3, and 34 cm-1 for [Fe2(μ-Cl)(μ-Lm*)2](ClO4)3. EPR spectra of [Cu

  5. Preparation and characterization of poly(glycidyl methacrylate)-grafted magnetic nanoparticles: Effects of the precursor concentration on polyol synthesis of Fe{sub 3}O{sub 4} and [PMDETA]{sub 0}/[CuBr{sub 2}]{sub 0} ratios on SI-AGET ATRP

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Liping; Zhou, Xuyang; Wei, Guyun; Lu, Xiaoduo; Wei, Weiping; Qiu, Jianhua

    2015-12-01

    Highlights: • The nanoparticle size of Fe{sub 3}O{sub 4} increased from 7.3 to 9.6 nm and the saturation magnetization of nanoparticles increased from 59 to 61 emu g{sup −1} with increasing the metal precursor concentration from 0.1 to 0.8 mol L{sup −1}, respectively. • The grafted content of PGMA increased from 4.1 to 23.1 wt% as the [PMDETA]{sub 0}/[CuBr{sub 2}]{sub 0} ratio decreased from 6:1 to 2:1. The PGMA-grafted Fe{sub 3}O{sub 4}@SiO{sub 2} magnetic microparticles were prepared by SI-AGET ATRP. - Abstract: Polymer brushes based on poly(glycidyl methacrylate) (PGMA) have been successfully grafted from the surface of silica coated iron oxide (Fe{sub 3}O{sub 4}@SiO{sub 2}) nanoparticles via surface-initiated activators generated by electron transfer atom transfer radical polymerization (SI-AGET ATRP). The size of the nanoparticles could be adjusted from 7.3 to 9.6 nm by varying the precursor concentration of iron(III) acetylacetonate. The Fe{sub 3}O{sub 4} nanoparticles possessed a highly crystalline structure, and the saturation magnetization of the as-prepared magnetite was strongly related to the particle size. Furthermore, the grafted PGMA content on the magnetic nanoparticles could be controlled by varying the ligand to transition metal ratio in a N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA)/CuBr{sub 2} catalyst system. The maximum grafted content was 23.1% at a ratio of [PMDETA]{sub 0}/[CuBr{sub 2}]{sub 0} = 2:1.

  6. High-speed CuBr brightness amplifier beam profile

    Science.gov (United States)

    Evtushenko, G. S.; Torgaev, S. N.; Trigub, M. V.; Shiyanov, D. V.; Evtushenko, T. G.; Kulagin, A. E.

    2017-01-01

    This paper addresses the experimental study of the beam profile of the CuBr brightness amplifier operating at a wide range of pulse repetition frequencies. The use of a medium-size gas discharge tube (2 cm) ensures the operation of the brightness amplifier both at typical PRFs (520 kHz) and at higher PRFs (up to 100 kHz), either with or without HBr additive. The effect of the active additive on the beam profile is demonstrated. The testing results on kinetic modeling of radial processes in the laser (brightness amplifier) plasma are also discussed.

  7. Magnetic studies of Fe/Cu multilayers

    Energy Technology Data Exchange (ETDEWEB)

    El Khiraoui, S. [Laboratoire de Physique et Mecanique des Materiaux, Universite Sultan Moulay Slimane, FST de Beni-Mellal, B.P. 523, 23000 Beni-Mellal (Morocco); Sajieddine, M. [Laboratoire de Physique et Mecanique des Materiaux, Universite Sultan Moulay Slimane, FST de Beni-Mellal, B.P. 523, 23000 Beni-Mellal (Morocco)], E-mail: sajieddinem@yahoo.fr; Hehn, M.; Robert, S.; Lenoble, O.; Bellouard, C. [Laboratoire de Physique des Materiaux, UMR-CNRS 7556, B.P. 239, 54506 Vandoeuvre-les-Nancy Cedex (France); Sahlaoui, M. [Laboratoire de Physique et Mecanique des Materiaux, Universite Sultan Moulay Slimane, FST de Beni-Mellal, B.P. 523, 23000 Beni-Mellal (Morocco); Benkirane, K. [Laboratoire des Materiaux, Micro-electronique, Automatique et Thermique, Faculte des Sciences Ain-Chock, Universite Hassan II, B.P. 5366 Maarif, Casablanca (Morocco)

    2008-07-01

    The structural and magnetic properties of sputtered Fe/Cu multilayers are examined as a function of Fe layer thickness t{sub Fe} by means of X-ray diffraction, Moessbauer spectrometry and superconducting quantum interference magnetometer. The temperature dependence of the spontaneous magnetization M(T) is well described by a T{sup 3/2} law in all multilayers in the temperature range 5-300 K. The interface anisotropy constant of Fe/Cu multilayers, K{sub s}, is found to be 0.31 and 0.45 erg/cm{sup 2} at 5 and 300 K, respectively. A spin-wave theory has been used to explain the temperature dependence of the magnetization and the approximate values for the bulk exchange interaction J{sub b}, surface exchange interaction J{sub s} and the interlayer coupling strength J{sub I} for various Fe layer thicknesses have been obtained.

  8. RbCuFe(PO42

    Directory of Open Access Journals (Sweden)

    Mongi Ben Amara

    2013-08-01

    Full Text Available A new iron phosphate, rubidium copper(II iron(III bis(phosphate, RbCuFe(PO42, has been synthesized as single crystals by the flux method. This compound is isostructural with KCuFe(PO42 [Badri et al. (2011, J. Solid State Chem. 184, 937–944]. Its structure is built up from Cu2O8 units of edge-sharing CuO5 polyhedra, interconnected by FeO6 octahedra through common corners to form undulating chains that extend infinitely along the [011] and [01-1] directions. The linkage of such chains is ensured by the PO4 tetraedra and the resulting three-dimensional framework forms quasi-elliptic tunnels parallel to the [101] direction in which the Rb+ cations are located.

  9. Magnetoelectric effects in the spiral magnets CuCl2 and CuBr2.

    Science.gov (United States)

    Tolédano, P; Ayala, A P; Furtado Filho, A F G; do Nascimento, J P C; Silva, M A S; Sombra, A S B

    2017-01-25

    The nature and symmetry of transition mechanisms in the spin-spiral copper halides CuCl2 and CuBr2 are analyzed theoretically. The magnetoelectric effects observed in the two multiferroic compounds are described and their phase diagram at zero and applied magnetic fields are worked out. The emergence of the electric polarization at zero field below the paramagnetic phase is shown to result from the coupling of two distinct spin-density waves and to be only partly related to the Dzialoshinskii-Moriya interactions. Applying a magnetic field along the two-fold monoclinic axis of CuCl2 yields a decoupling of the spin-density waves modifying the symmetry of the phase and the spin-spiral orientation. The remarkable periodic dependences of the magnetic susceptibility and polarization, on rotating the field in the monoclinic plane, are described theoretically.

  10. Electrodeposited NiFeCu/Cu multilayers: Effect of Fe ion concentration on properties

    Energy Technology Data Exchange (ETDEWEB)

    Kuru, Hilal, E-mail: htopcu@balikesir.edu.tr [Physics Department, Science and Literature Faculty, Balikesir University, Balikesir 10145 (Turkey); Kockar, Hakan, E-mail: hkockar@balikesir.edu.tr [Physics Department, Science and Literature Faculty, Balikesir University, Balikesir 10145 (Turkey); Alper, Mursel, E-mail: malper@uludag.edu.tr [Physics Department, Science and Literature Faculty, Uludag University, Gorukle, Bursa 16059 (Turkey)

    2015-01-01

    A series of 125[NiFeCu(3 nm)/Cu(1 nm)] multilayers were electrodeposited on strong (110) textured Cu substrates from electrolytes containing different Fe ion concentrations under potentiostatic control. The compositional analysis by energy dispersive X-ray spectroscopy demonstrated that as the Fe ion concentration in the electrolyte is increased, the Fe content of the multilayers increased. X-ray diffraction measurements indicated that all samples exhibited a face-centred cubic structure with a strong (110) texture as their substrates. The surface images obtained by scanning electron microscopy disclosed that all films have smooth surfaces. Magnetoresistance measurements were carried out at room temperature with magnetic fields up to ±12 kOe. All samples exhibited giant magnetoresistance (GMR) and the maximum GMR value of 5% was obtained in the multilayer grown from the electrolyte containing 0.0036 M Fe ion concentration. The GMR magnitude changed depending on the film contents arising from the variation of the Fe ion concentration in the electrolyte. The magnetic properties studied with the vibrating sample magnetometer showed that the saturation magnetisation changed, and the coercivities decreased with varying Fe ion concentration in the electrolyte. The changes observed in the properties were ascribed to the variations observed in the film composition caused by the Fe ion concentration of the electrolyte. - Highlights: • NiFeCu/Cu multilayers were potentiostatically electrodeposited on Cu substrates. • All films had a face-centred cubic structure irrespective of the film content. • All samples exhibited GMR and the maximum GMR value was 5%. • The saturation magnetisation changed, and the coercivities decreased with varying Fe ion concentration in the electrolyte.

  11. Magnetism of CuX2 frustrated chains (X = F, Cl, Br): Role of covalency

    Science.gov (United States)

    Lebernegg, S.; Schmitt, M.; Tsirlin, A. A.; Janson, O.; Rosner, H.

    2013-04-01

    Periodic and cluster density functional theory (DFT) calculations, including DFT+U and hybrid functionals, are applied to study magnetostructural correlations in spin-(1)/(2) frustrated chain compounds CuX2: CuCl2, CuBr2, and a fictitious chain structure of CuF2. The nearest-neighbor and second-neighbor exchange integrals J1 and J2 are evaluated as a function of the Cu-X-Cu bridging angle θ in the physically relevant range 80∘-110∘. In the ionic CuF2, J1 is ferromagnetic for θ≤100∘. For larger angles, the antiferromagnetic superexchange contribution becomes dominant, in accord with the Goodenough-Kanamori-Anderson rules. However, both CuCl2 and CuBr2 feature ferromagnetic J1 in the whole angular range studied. This surprising behavior is ascribed to the increased covalency in the Cl and Br compounds, which amplifies the contribution from Hund's exchange on the ligand atoms and renders J1 ferromagnetic. At the same time, the larger spatial extent of X orbitals enhances the antiferromagnetic J2, which is realized via the long-range Cu-X-X-Cu paths. Both periodic and cluster approaches supply a consistent description of the magnetic behavior which is in good agreement with the experimental data for CuCl2 and CuBr2. Thus, owing to their simplicity, cluster calculations have excellent potential to study magnetic correlations in more involved spin lattices, and facilitate application of quantum-chemical methods.

  12. Modeling of Output Characteristics of a UV Cu+ Ne-CuBr Laser

    Directory of Open Access Journals (Sweden)

    Snezhana Georgieva Gocheva-Ilieva

    2012-01-01

    Full Text Available This paper examines experiment data for a Ne-CuBr UV copper ion laser excited by longitudinal pulsed discharge emitting in multiline regime. The flexible multivariate adaptive regression splines (MARSs method has been used to develop nonparametric regression models describing the laser output power and service life of the devices. The models have been constructed as explicit functions of 9 basic input laser characteristics. The obtained models account for local nonlinearities of the relationships within the various multivariate subregions. The built best MARS models account for over 98% of data. The models are used to estimate the investigated output laser characteristics of existing UV lasers. The capabilities for using the models in predicting existing and future experiments have been demonstrated. Specific analyses have been presented comparing the models with actual experiments. The obtained results are applicable for guiding and planning the engineering experiment. The modeling methodology can be applied for a wide range of similar lasers and laser devices.

  13. Menopause effect on blood Fe and Cu isotope compositions.

    Science.gov (United States)

    Jaouen, Klervia; Balter, Vincent

    2014-02-01

    Iron (δ(56) Fe) and copper (δ(65) Cu) stable isotope compositions in blood of adult human include a sex effect, which still awaits a biological explanation. Here, we investigate the effect of menopause by measuring blood δ(56) Fe and δ(65) Cu values of aging men and women. The results show that, while the Fe and Cu isotope compositions of blood of men are steady throughout their lifetime, postmenopausal women exhibit blood δ(65) Cu values similar to men, and δ(56) Fe values intermediate between men and premenopausal women. The residence time of Cu and Fe in the body likely explains why the blood δ(65) Cu values, but not the δ(56) Fe values, of postmenopausal women resemble that of men. We suggest that the Cu and Fe isotopic fractionation between blood and liver resides in the redox reaction occurring during hepatic solicitation of Fe stores. This reaction affects the Cu speciation, which explains why blood Cu isotope composition is impacted by the cessation of menstruations. Considering that Fe and Cu sex differences are recorded in bones, we believe this work has important implications for their use as a proxy of sex or age at menopause in past populations. Copyright © 2013 Wiley Periodicals, Inc.

  14. [Oxidation of mercury by CuBr2 decomposition under controlled-release membrane catalysis condition].

    Science.gov (United States)

    Hu, Lin-Gang; Qu, Zan; Yan, Nai-Qiang; Guo, Yong-Fu; Xie, Jiang-Kun; Jia, Jin-Ping

    2014-02-01

    CuBr2 in the multi-porous ceramic membrane can release Br2 at high temperature, which was employed as the oxidant for Hg0 oxidation. Hg0 oxidation efficiency was studied by a membrane catalysis device. Meanwhile, a reaction and in situ monitoring device was designed to avoid the impact of Br2 on the downstream pipe. The result showed that the MnO(x)/alpha-Al2O3 catalysis membrane had a considerable "controlled-release" effect on Br2 produced by CuBr2 decomposition. The adsorption and reaction of Hg0 and Br2 on the surface of catalysis membrane obeyed the Langmuir-Hinshelwood mechanism. The removal efficiency of Hg0 increased with the rising of Br2 concentration. However, when Br2 reached a certain concentration, the removal efficiency was limited by adsorption rate and reaction rate of Hg0 and Br2 on the catalysis membrane. From 473 K to 573 K, the variation of Hg0 oxidation efficiency was relatively stable. SO2 in flue gas inhibited the oxidation of Hg0 while NO displayed no obvious effect.

  15. Heteropoly acid promoted Cu and Fe catalysts for the selective catalytic reduction of NO with ammonia

    DEFF Research Database (Denmark)

    Putluru, Siva Sankar Reddy; Mossin, Susanne L.; Riisager, Anders

    2011-01-01

    Cu/TiO2, Fe/TiO2 and heteropoly acid promoted Cu/TiO2, Fe/TiO2 catalysts were prepared and characterized by N2 physisorption, XRPD, NH3-TPD, H2-TPR and EPR. The catalysts exhibited only crystalline TiO2 phases with the active metals and promoters in highly dispersed state. The acidic properties...... activity and acidity was lower for promoted catalysts than for unpromoted catalysts. In the heteropoly acid promoted catalysts the SCR active Cu and Fe metals were protected from potassium poisons by bonding of the potassium to the Brønsted acid centres. Thus heteropoly acid promoted catalysts might...

  16. Magnetic properties of nanostructured CuFe2O4

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Goya, G.F.; Rechenberg, H.R.

    1999-01-01

    The structural evolution and magnetic properties of nanostructured copper ferrite, CuFe2O4, have been investigated by X-ray diffraction, Mossbauer spectroscopy, and magnetization measurements. Nanometre-sized CuFe2O4 particles with a partially inverted spinel structure were synthesized by high...

  17. Comparative study of the magnetoresistance of MBE-grown multilayers: [Fe/Cu/Co/Cu]N and [Fe/Cu]N[Co/Cu]N

    Science.gov (United States)

    Bozec, D.; Walker, M. J.; Hickey, B. J.; Howson, M. A.; Wiser, Nathan

    1999-08-01

    We have carried out measurements of the magnetic-field dependence of the magnetoresistance [MR(H)] in the current perpendicular to the plane (CPP) mode for magnetic multilayers having the following configurations: [Fe/Cu/Co/Cu]N and [Fe/Cu]N[Co/Cu]N. The two configurations had the same number, types, and thicknesses of magnetic and nonmagnetic layers; their only difference lay in the ordering of the magnetic layers. Nevertheless, the measured MR(H) curves are found to be completely different for the two configurations. The implications of these results are discussed for the spin-diffusion length.

  18. Isotopic Evidence of Unaccounted for Fe and Cu Erythropoietic Pathways

    Science.gov (United States)

    Albarede, F.; Telouk, P.; Lamboux, A.; Jaouen, K.; Balter, V.

    2011-12-01

    Despite its potential importance for understanding perturbations in the Fe-Cu homeostatic pathways, the natural isotopic variability of these metals in the human body remains unexplored. We measured the Fe, Cu, and Zn isotope compositions of total blood, serum, and red blood cells of ~50 young blood donors by multiple-collector ICP-MS after separation and purification by anion exchange chromatography. Zn is on average 0.2 permil heavier in erythrocytes (δ 66Zn=0.44±0.33 permil) with respect to serum but shows much less overall isotopic variability than Fe and Cu, which indicates that isotope fractionation depends more on redox conditions than on ligand coordination. On average, Fe in erythrocytes (δ 56Fe=-2.59±0.47 permil) is isotopically light by 1-2 permil with respect to serum, whereas Cu in erythrocytes (δ 65Cu=0.56±0.50 permil) is 0.8 percent heavier. Fe and Cu isotope compositions clearly separate erythrocytes of men and women. Fe and Cu from B-type men erythrocytes are visibly more fractionated than all the other blood types. Isotope compositions provide an original method for evaluating metal mass balance and homeostasis. Natural isotope variability shows that the current models of Fe and Cu erythropoiesis, which assume that erythropoiesis is restricted to bone marrow, violate mass balance requirements. It unveils unsuspected major pathways for Fe, with erythropoietic production of isotopically heavy ferritin and hemosiderin, and for Cu, with isotopically light Cu being largely channeled into blood and lymphatic circulation rather than into superoxide dismutase-laden erythrocytes. Iron isotopes provide an intrinsic measuring rod of the erythropoietic yield, while Cu isotopes seem to gauge the relative activity of erythropoiesis and lymphatics.

  19. Cu clustering stage before the crystallization in Fe-Si-B-Nb-Cu amorphous alloys

    DEFF Research Database (Denmark)

    Ohnuma, M.; Hono, K.; Onodera, H.

    1999-01-01

    The Cu clustering stage before the crystallization of Fe-Si-B-Nb-Cu amorphous alloys have been studied by three dimensional atom probe (3DAP) small-angle neutron scattering (SANS) and high sensitive differential calorimetry (DSC). Cu clustering occurs prior to the onset of the primary crystalliza......The Cu clustering stage before the crystallization of Fe-Si-B-Nb-Cu amorphous alloys have been studied by three dimensional atom probe (3DAP) small-angle neutron scattering (SANS) and high sensitive differential calorimetry (DSC). Cu clustering occurs prior to the onset of the primary...... crystallization reaction. The number of the clusters estimated by 3DAP is large enough to provide heterogeneous nucleation sites to all bcc/D0(3) Fe-Si crystals which appear at higher temperatures. This fact indicates that the distribution of nanocrystalline Fe-Si is strongly affected by that of the Cu...

  20. Synthesis and photoluminescence properties of an unprecedented phosphinine-Cu4Br4 cluster

    NARCIS (Netherlands)

    Roesch, Philipp; Nitsch, Jörn; Lutz, Martin|info:eu-repo/dai/nl/304828971; Wiecko, Jelena; Steffen, Andreas; Müller, Christian

    2014-01-01

    A hitherto unprecedented polynuclear phosphinine-Cu(I) complex has been prepared and crystallographically characterized. The molecular structure in the crystal verifies the presence of the heterocubanetype tetrameric cluster [LCuBr]4 (L = 2,4-diphenyl-5-methyl-6-(2,3- dimethylphenyl)phosphinine),

  1. Cu1-x Fe x O: hopping transport and ferromagnetism.

    Science.gov (United States)

    Nasir, Mohd; Islam, Rakibul; Ahmed, Md A; Ayaz, Saniya; Kumar, Gautham; Kumar, Sunil; Prajapat, C L; Roussel, Frederick; Biring, Sajal; Sen, Somaditya

    2017-09-01

    Single phase, sol-gel prepared Cu1-x Fe x O (0 ≤ x ≤ 0.125) powders are characterized in terms of structural, electronic and magnetic properties. Using dielectric and magnetic studies we investigate the coupling of electron and spin. The electrical conductivities and activation energies are studied with increasing Fe content. Modelling of experimental conductivity data emphasizes a single hopping mechanism for all samples except x = 0.125, which have two activation energies. Hole doping is confirmed by confirming a majority Fe3+ substitution of Cu2+ in CuO from X-ray photoelectron spectroscopy studies (XPS). Such a substitution results in stabilized ferromagnetism. Fe substitution introduces variation in coercivity as an intrinsic magnetic property in Fe-doped CuO, and not as a secondary impurity phase.

  2. (C5H12NCu2Br3: A Piperidinium Copper(I Bromide with [Cu2Br3]− Ladders

    Directory of Open Access Journals (Sweden)

    Karl W. Krämer

    2012-10-01

    Full Text Available Piperidinium copper(I bromide, (C5H12NCu2Br3, was obtained from a solution of CuBr2, piperidine, and HBr in ethanol. At 60 °C ethanol slowly reduces copper(II to copper(I. Colorless plates of (C5H12NCu2Br3 crystallize in the triclinic space group P-1 with lattice parameters of a = 6.2948(10 Å, b = 8.2624(14 Å, c = 10.7612(17 Å, α = 75.964(19°, β = 89.232(19°, γ = 84.072(19°, and Z = 2 at 173 K. [CuBr4] tetrahedra share edges and form [Cu2Br3]− ladders parallel to the a-axis. (C5H12N+ ions adopt a chair conformation and connect the [Cu2Br3]− ladders via H-bonding. The (C5H12NCu2Br3 structure is related to the mineral rasvumite, KFe2S3, space group Cmcm, which is isostructural to several alkali copper(I halides.

  3. First principles calculations of interlayer exchange coupling in bcc Fe/Cu/Fe structures

    Energy Technology Data Exchange (ETDEWEB)

    Kowalewski, M.; Heninrich, B. [Simon Fraser Univ., Burnaby, British Columbia (Canada); Schulthess, T.C.; Butler, W.H. [Oak Ridge National Lab., TN (United States)

    1998-01-01

    The authors report on theoretical calculations of interlayer exchange coupling between two Fe layers separated by a modified Cu spacer. These calculations were motivated by experimental investigations of similar structures by the SFU group. The multilayer structures of interest have the general form: Fe/Cu(k)/Fe and Fe/Cu(m)/X(1)/Cu(n)/Fe where X indicates one AL (atomic layer) of foreign atoms X (Cr, Ag, or Fe) and k, m, n represent the number of atomic layers of Cu. The purpose of the experimental and theoretical work was to determine the effect of modifying the pure Cu spacer by replacing the central Cu atomic layer with the atomic layer of foreign atoms X. The first principles calculation were performed using the Layer Korringa-Kohn-Rostoker (LKKR) method. The theoretical thickness dependence of the exchange coupling between two semi-infinite Fe layers was calculated for pure Cu spacer thicknesses in the range of 0 < k < 16. The effect of the foreign atoms X on the exchange coupling was investigated using the structure with 9 AL Cu spacer as a reference sample. The calculated changes in the exchange coupling are in qualitative agreement with experiment.

  4. Determination of Cu/Zn and Fe in human serum of patients with sickle cell anemia using radiation synchrotron

    Energy Technology Data Exchange (ETDEWEB)

    Canellas, C.G.L. [Nuclear Instrumentation Laboratory, COPPE/UFRJ, P.O. Box 68509, 21.941-972 Rio de Janeiro (Brazil); Carvalho, S.M.F. [State Institute of Hematology Arthur de Siqueira Cavalcanti, 20.211-030 Rio de Janeiro (Brazil); Anjos, M.J. [Nuclear Instrumentation Laboratory, COPPE/UFRJ, P.O. Box 68509, 21.941-972 Rio de Janeiro (Brazil); Physics Institute, State University of Rio de Janeiro, 20.559-900 Rio de Janeiro (Brazil); Lopes, R.T., E-mail: ricardo@lin.ufrj.br [Nuclear Instrumentation Laboratory, COPPE/UFRJ, P.O. Box 68509, 21.941-972 Rio de Janeiro (Brazil)

    2012-07-15

    In this work we analyzed serum samples from patients with Sickle Cell Anemia (SCA) using Total Reflection X-Ray Fluorescence using Synchrotron Radiation (SRTXRF). The SRTXRF measurements were performed at the X-Ray Fluorescence Beamline at the Brazilian National Synchrotron Light Laboratory (LNLS). We studied forty-three patients aged 18-50 suffering from SCA and sixty healthy volunteers aged 18-60. It was possible to determine the concentrations of the following elements: P, S, Cl, K, Ca, Fe, Cu, Zn, Br and Rb. Moreover, there are evidences of an association among Fe, Cu, Zn and Cu/Zn in the SCA pathogenesis process. The concentrations of Fe and Cu in the serum samples of patients with SCA were larger, 120% and 20%, respectively, when compared with the CG. The serum level Cu/Zn ratio was significantly higher (60%) in the serum samples from patients suffering from SCA than from the CG. Therefore, the Cu/Zn ratio can be used as an adjuvant index in enhancement for diagnosis of SCA. - Highlights: Black-Right-Pointing-Pointer Serum samples from patients with Sickle Cell Anemia (SCA) were analyzed by SRTXRF. Black-Right-Pointing-Pointer It was possible to determine the concentrations of the P, S, Cl, K, Ca, Fe, Cu, Zn, Br and Rb. Black-Right-Pointing-Pointer There are evidences of an association among Fe, Cu, Zn and Cu/Zn in the SCA process. Black-Right-Pointing-Pointer The results indicate that the Cu/Zn ratio can be used as an adjuvant index for diagnosis of SCA.

  5. Superparamagnetism in CuFeInTe{sub 3} and CuFeGaTe{sub 3} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Grima-Gallardo, P.; Alvarado, F.; Munoz, M.; Duran, S.; Quintero, M.; Nieves, L.; Quintero, E.; Tovar, R.; Morocoima, M. [Centro de Estudios en Semiconductores (CES), Fac. Ciencias, Dpto. Fisica, Universidad de Los Andes, Merida (Venezuela); Ramos, M.A. [Laboratorio de Difraccion y Fluorescencia de Rayos-X, Instituto Zuliano de Investigaciones Tecnologicas (INZIT), La Canada de Urdaneta, Estado Zulia (Venezuela)

    2012-06-15

    The temperature dependencies of DC magnetic susceptibilities, {chi}(T), of CuFeInTe{sub 3} and CuFeGaTe{sub 3} alloys were measured in a SQUID apparatus using the protocol of field cooling (FC) and zero FC (ZFC). The FC curves of both samples reflect a weak ferromagnetic (or ferrimagnetic) behavior with a nearly constant value of {chi}(T) in the measured temperature range (2-300 K) indicating that the critical temperatures (T{sub c}) are >300 K. The ZFC curves diverges from FC, showing irreversibility temperatures (T{sub irr}) of {proportional_to}250 K for CuFeInTe{sub 3} and >300 K for CuFeGaTe{sub 3}, suggesting that we are dealing with cluster-glass systems in a superparamagnetic state. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Charge transfer and relativistic effects in the low-lying electronic states of CuCl, CuBr and CuI

    NARCIS (Netherlands)

    Sousa, C; de Jong, W.A.; Broer, R.; Nieuwpoort, WC

    1997-01-01

    The spectral transitions and the character of the low-lying excited states of the copper halides, CuX (X = Cl, Br, I) are studied by means of two different relativistic computational approaches. One is based on the CASSCF/CASPT2 approach with operators accounting for scalar relativistic effects

  7. Photoelectron diffraction of magnetic ultrathin films: Fe/Cu(001)

    Energy Technology Data Exchange (ETDEWEB)

    Tobin, J.G. (Lawrence Livermore National Lab., CA (USA)); Wagner, M.K. (Wisconsin Univ., Madison, WI (USA). Dept. of Chemistry); Guo, X.Q.; Tong, S.Y. (Wisconsin Univ., Milwaukee, WI (USA). Dept. of Physics)

    1991-01-03

    The preliminary results of an ongoing investigation of Fe/Cu(001) are presented here. Energy dependent photoelectron diffraction, including the spin-dependent variant using the multiplet split Fe3s state, is being used to investigate the nanoscale structures formed by near-monolayer deposits of Fe onto Cu(001). Core-level photoemission from the Fe3p and Fe3s states has been generated using synchrotron radiation as the tunable excitation source. Tentatively, a comparison of the experimental Fe3p cross section measurements with multiple scattering calculations indicates that the Fe is in a fourfold hollow site with a spacing of 3.6{Angstrom} between it and the atom directly beneath it, in the third layer. This is consistent with an FCC structure. The possibility of utilizing spin-dependent photoelectron diffraction to investigate magnetic ultrathin films will be demonstrated, using our preliminary spectra of the multiplet-split Fe3s os near-monolayer Fe/Cu(001). 18 refs., 10 figs.

  8. Anomalous superconducting spin-valve effect in NbN/FeN/Cu/FeN/FeMn multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Tae Jong; Kim, Dong Ho [Yeungnam University, Gyeongsan (Korea, Republic of)

    2017-09-15

    We have studied magnetic and transport properties of NbN/FeN/Cu/FeN/FeMn spin-valve structure. In-plane magnetic moment exhibited typical hysteresis loops of spin valves in the normal state of NbN film at 20 K. On the other hand, the magnetic hysteresis loop in the superconducting state exhibited more complex behavior in which exchange bias provided by antiferrmagnetic FeMn layer to adjacent FeN layer was disturbed by superconductivity. Because of this, the ideal superconducting spin-valve effect was not detected. Instead the stray field originated from unsaturated magnetic states dominated the transport properties of NbN/FeN/Cu/FeN/FeMn multilayer.

  9. Role of Cu During Sintering of Fe0.96Cu0.04 Nanoparticles

    Science.gov (United States)

    Sivaprahasam, D.; Sriramamurthy, A. M.; Bysakh, S.; Sundararajan, G.; Chattopadhyay, K.

    2018-01-01

    Nanoparticle agglomerates of passivated Fe (n-Fe) and Fe0.96Cu0.04 (n-Fe0.96Cu0.04), synthesized through the levitational gas condensation (LGC) process, were compacted and sintered using the conventional powder metallurgy method. The n-Fe0.96Cu0.04 agglomerates produced lower green density than n-Fe, and when compacted under pressure beyond 200 MPa, they underwent lateral cracking during ejection attributed to the presence of a passive oxide layer. Sintering under dynamic hydrogen atmosphere can produce a higher density of compact in n-Fe0.96Cu0.04 in comparison to n-Fe. Both the results of dilatometry and thermogravimetric (TG) measurements of the samples under flowing hydrogen revealed enhancement of the sintering process as soon as the reduction of oxide layers could be accomplished. The shrinkage rate of n-Fe0.96Cu0.04 reached a value three times higher than n-Fe at a low temperature of 723 K (450 °C) during heating. This enhanced shrinkage rate was the manifestation of accumulation of Cu at the surface of the particles. The formation of a thin-surface melted layer enriched with copper during heating to isothermal holding facilitated as a medium of transport for diffusion of the elements. The compacts produced by sintering at 773 K (500 °C), with relative density 82 pct, were found to be unstable and oxidized instantly when exposed to ambient atmosphere. The stable compacts of density more than 92 pct with 300- to 450-nm grain size could only be produced when sintering was carried out at 973 K (700 °C) and beyond. The 0.22 wt pct residual oxygen obtained in the sintered compact is similar to what is used for conventional ferrous powder metallurgy products.

  10. Crystallization behavior and magnetic properties in High Fe content FeBCSiCu alloy system

    Energy Technology Data Exchange (ETDEWEB)

    Fan, X.D., E-mail: fanxd@seu.edu.cn; Shen, B.L., E-mail: blshen@seu.edu.cn

    2015-07-01

    High Fe content FeBCSiCu nanocrystalline alloys are prepared by annealing melt-spun amorphous ribbons with aim at increasing saturation magnetic flux density. Microstructures identified by XRD and TEM reveal that Cu addition inhibits the surface crystallization of Fe{sub 86}B{sub 7}C{sub 7} alloy and improve its glass-forming ability. Activation energy of crystallization calculated by Kissinger's equation indicates that both Cu and Si addition promotes the precipitation of α-Fe phase and improves the thermal stability. VSM and DC B–H loop tracer measurements show that the Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy exhibits high saturation magnetic flux density of 1.8 T and low coercivity of 10 A/m, respectively. AC properties measured by AC B–H analyzer show this alloy exhibits low core loss of 0.35 W/kg at 1 T at 50 Hz. Low material cost and convenient productivity make the Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy an economical application in industry. - Highlights: • Cu addition inhibits the surface crystallization and improves the GFA. • The competitive formation of Fe{sub 3}C and α-Fe phase impedes the devitrification. • Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy exhibits excellent magnetic properties. • The alloy system has an economical advantage and convenient productivity.

  11. Magnetically separable Ag/AgBr/NiFe2O4 composite as a highly efficient visible light plasmonic photocatalyst

    Science.gov (United States)

    Ge, Ming; Liu, Wei; Hu, Xin-Rong; Li, Zhen-Lu

    2017-10-01

    A magnetic Ag/AgBr/NiFe2O4 plasmonic photocatalyst was firstly prepared by coupling a hydrothermal route with a solvothermal method. The as-synthesized Ag/AgBr/NiFe2O4 was characterized by XRD, XPS, FE-SEM, UV-vis DRS, PL and BET surface area. Under visible light irradiation, the resulting Ag/AgBr/NiFe2O4 exhibited a higher photocatalytic activity for rhodamine B (RhB) degradation compared with Ag/AgBr, which was ascribed to the heterostructured Ag/AgBr/NiFe2O4 and the surface plasmon resonance (SPR) effect of Ag nanoparticles. Moreover, the Ag/AgBr/NiFe2O4 plasmonic photocatalyst can be recovered and recycled by a magnetic field along with good stability. A plausible mechanism is also proposed via active species trapping experiments, which indicating that the superoxide radicals (O2-•) are the main reactive oxygen species for RhB degradation in Ag/AgBr/NiFe2O4 suspension under visible light.

  12. Solid FeS lubricant: a possible alternative to MoS2 for Cu-Fe-based friction materials

    Science.gov (United States)

    Peng, Tao; Yan, Qing-zhi; Zhan, Xiao-lu; Shi, Xiao-jiao

    2017-11-01

    Molybdenum disulfide (MoS2) is one of the most commonly used solid lubricants for Cu-Fe-based friction materials. Nevertheless, MoS2 reacts with metal matrices to produce metal sulfides (e.g., FeS) and Mo during sintering, and the lubricity of the composite may be related to the generation of FeS. Herein, the use of FeS as an alternative to MoS2 for producing Cu-Fe-based friction materials was investigated. According to the reaction principle of thermodynamics, two composites—one with MoS2 (Fe-Cu-MoS2 sample) and the other with FeS (FeS-Cu2S-Cu-Fe-Mo sample), were prepared and their friction behaviors and mechanical properties were compared. The results showed that MoS2 reacted with the Cu-Fe matrix to produce FeS, metallic ternary sulfides, and Mo when sintered at 1050°C. The MoS2-Cu-Fe and FeS-Cu2S-Cu-Fe-Mo samples thereby exhibited similar characteristics with respect to phase composition, density, hardness, and tribological behaviors. Micrographs of the worn surfaces revealed that the stable friction regime for both composites stemmed from the iron sulfides friction layers rather than from the molybdenum sulfides layers.

  13. Kinetic process of mechanical alloying in Fe50Cu50

    DEFF Research Database (Denmark)

    Huang, J.Y.; Jiang, Jianzhong; Yasuda, H.

    1998-01-01

    It is shown that mechanical alloying in the immiscible Fe-Cu system is governed by the atomic shear event and shear-induced diffusion process. We found that an alpha-to-gamma phase transformation, as evidenced by the Nishiyama-Wasserman orientation relationship, occurs by simultaneous shearing...... structures, until a complete fee Fe-Cu solid solution is formed. The results provide significant insight into the understanding of recent experiments showing that chemical mixing of immiscible elements can bd induced by mechanical alloying. [S0163-1829(98)51342-2]....

  14. Increased surface spin stability in γ-Fe2O3 nanoparticles with a Cu shell

    Science.gov (United States)

    Desautels, R. D.; Skoropata, E.; Chen, Y.-Y.; Ouyang, H.; Freeland, J. W.; van Lierop, J.

    2012-04-01

    γ-Fe2O3 nanoparticles were coated with a Cu shell in situ during synthesis. An interfacial monolayer of CuO in the Cu-coated γ-Fe2O3 nanoparticles was discovered that stabilized the disordered surface spins of γ-Fe2O3 nanoparticles. Element-specific x-ray absorption spectroscopy at the L-edges for Cu and Fe indicated the magnetic moment of the Cu in the shell interacted with the γ-Fe2O3 nanoparticle’s surface magnetic moments. This exchange interaction between the Fe and Cu at the interface permitted an overall Cu moment in CuO (an antiferromagnet typically) that altered the γ-Fe2O3 nanomagnetism. Increasing the Cu shell thickness also increased the total Fe magnetism of the nanoparticles.

  15. Antiperovskite Chalco-Halides Ba3(FeS4)Cl, Ba3(FeS4)Br, and Ba3(FeSe4)Br with Spin Super-Super Exchange

    Science.gov (United States)

    Zhang, Xian; Liu, Kai; He, Jian-Qiao; Wu, Hui; Huang, Qing-Zhen; Lin, Jian-Hua; Lu, Zhong-Yi; Huang, Fu-Qiang

    2015-11-01

    Perovskite-related materials have received increasing attention for their broad applications in photovoltaic solar cells and information technology due to their unique electrical and magnetic properties. Here we report three new antiperovskite chalco-halides: Ba3(FeS4)Cl, Ba3(FeS4)Br, and Ba3(FeSe4)Br. All of them were found to be good solar light absorbers. Remarkably, although the shortest Fe-Fe distance exceeds 6 Å, an unexpected anti-ferromagnetic phase transition near 100 K was observed in their magnetic susceptibility measurement. The corresponding complex magnetic structures were resolved by neutron diffraction experiments as well as investigated by first-principles electronic structure calculations. The spin-spin coupling between two neighboring Fe atoms along the b axis, which is realized by the Fe-S···S-Fe super-super exchange mechanism, was found to be responsible for this magnetic phase transition.

  16. Anomaly observed in Moessbauer spectra near the neel temperature of FeBr sub 2

    CERN Document Server

    Naili Di

    2003-01-01

    In several decades, iron(II) bromide (FeBr sub 2) has been investigated as a typical Ising-type antiferromagnet by several kinds of experimental techniques. By the Moessbauer measurements, it was normally observed that only the magnetic spectrum appeared just below Neel temperature in FeBr sub 2. However, we found the anomalous spectra, in which paramagnetic component coexisted with magnetic one near Neel temperature. For two kinds of single crystal FeBr sub 2 samples, IM and IIM, we determined the Moessbauer parameters of the observed spectra by the computer analyses: the relative absorption intensity I sub p of the paramagnetic component to the total absorption area of the best fitting spectrum and the value of the hyperfine field H sub h sub f of the magnetic component and values of the quadrupole splitting 1/2 centre dot e sup 2 qQ of the magnetic and the paramagnetic components. The temperature variation of H sub h sub f is unique and the same as that observed for the sample in which the anomaly was not ...

  17. Properties of electrodeposited CoFe/Cu multilayers: The effect of Cu layer thickness

    Energy Technology Data Exchange (ETDEWEB)

    Sahin, Turgut, E-mail: stsahin4@hotmail.com [Deparment of Physics, Science and Literature Faculty, Balikesir University, 10100 Balikesir (Turkey); Kockar, Hakan, E-mail: hkockar@balikesir.edu.tr [Deparment of Physics, Science and Literature Faculty, Balikesir University, 10100 Balikesir (Turkey); Alper, Mursel, E-mail: malper@uludag.edu.tr [Deparment of Physics, Science and Literature Faculty, Uludag University, 16059 Gorukle, Bursa (Turkey)

    2015-01-01

    CoFe/Cu multilayers were potentiostatically electrodeposited on Ti substrates as a function of different non-magnetic (Cu) layer thicknesses, and their characterizations were investigated. The compositional analysis performed by energy dispersive X-ray spectroscopy disclosed that the Cu content in the multilayers increased and the Co content decreased as non-magnetic layer was increased. However, the Fe content was almost stable. The scanning electron microscopy studies showed that the surface morphology of the films is strongly affected by the non-magnetic layer thickness, and X-ray diffraction was used to analyse the structural properties of the multilayers and revealed that the multilayers have face-centred cubic (fcc) structure and their preferred orientations change depending on the Cu layer thickness. In the case of magnetoresistance measurements of the multilayers performed at room temperature, the highest giant magnetoresistance (GMR) values exhibited for the films with the Cu layer thickness (6.0 nm) whereas the lowest GMR magnitudes were observed for the films without Cu layer. Therefore, the variations of the Cu layer thicknesses were observed to have a significant effect on the GMR of multilayers. The differences observed in the magnetotransport properties were attributed to the microstructural changes caused by the Cu layer thickness. - Highlights: • CoFe/Cu multilayers were potentiostatically electrodeposited on Ti substrates. • Microstructural and magnetoresistance properties of CoFe/Cu multilayers were investigated. • All films had a face-centred cubic structure irrespective of the multilayer content. • All samples exhibited GMR and the maximum GMR value was 11%.

  18. Crystallization behavior and magnetic properties in High Fe content FeBCSiCu alloy system

    Science.gov (United States)

    Fan, X. D.; Shen, B. L.

    2015-07-01

    High Fe content FeBCSiCu nanocrystalline alloys are prepared by annealing melt-spun amorphous ribbons with aim at increasing saturation magnetic flux density. Microstructures identified by XRD and TEM reveal that Cu addition inhibits the surface crystallization of Fe86B7C7 alloy and improve its glass-forming ability. Activation energy of crystallization calculated by Kissinger's equation indicates that both Cu and Si addition promotes the precipitation of α-Fe phase and improves the thermal stability. VSM and DC B-H loop tracer measurements show that the Fe85.5B7C6Si1Cu0.5 nanocrystalline alloy exhibits high saturation magnetic flux density of 1.8 T and low coercivity of 10 A/m, respectively. AC properties measured by AC B-H analyzer show this alloy exhibits low core loss of 0.35 W/kg at 1 T at 50 Hz. Low material cost and convenient productivity make the Fe85.5B7C6Si1Cu0.5 nanocrystalline alloy an economical application in industry.

  19. In situ determination of aging precipitation in deformed Fe-Cu and Fe-Cu-B-N alloys by time-resolved small-angle neutron scattering

    NARCIS (Netherlands)

    He, S.M.; Van Dijk, N.H.; Paladugu, M.; Schut, H.; Kohlbrecher, J.; Tichelaar, F.D.; Van der Zwaag, S.

    2010-01-01

    We performed in situ time-resolved small-angle neutron scattering (SANS) measurements on high-purity Fe-Cu and Fe-Cu-B-N alloys during isothermal aging at 550 °C in order to study the potential self-healing of deformation-induced defects by nanosized Cu precipitation. Three different samples with

  20. Comparison of trace element contamination levels (Cu, Zn, Fe, Cd ...

    African Journals Online (AJOL)

    Comparison of trace element contamination levels (Cu, Zn, Fe, Cd and Pb) in the soft tissues of the gastropods Tympanotonus fuscatus fuscatus and Tf radula collected in the Ebrié Lagoon (Côte d'Ivoire): Evidence of the risks linked to linked to lead and.

  1. Determination of Fe, Zn, and Cu concentrations in tobacco leaves ...

    African Journals Online (AJOL)

    user

    ABSTRACT: This paper reports the results of the determination of the concentrations of. Zn, Cu, and Fe in tobacco leaves and snuff products on sale in some regional markets in. Imo State, Southeastern Nigeria. The samples were ashed at 550°C, mineralized with acid and the metal concentrations measured using flame ...

  2. Characterisations of CoFeCu films: Influence of Fe concentration

    Energy Technology Data Exchange (ETDEWEB)

    Kockar, Hakan, E-mail: hkockar@balikesir.edu.tr [Physics Department, Science and Literature Faculty, Balikesir University, 10145 Cagis, Balikesir (Turkey); Ozergin, Ercument, E-mail: ercmentz@yahoo.com [Physics Department, Science and Literature Faculty, Balikesir University, 10145 Cagis, Balikesir (Turkey); Karaagac, Oznur, E-mail: karaagac@balikesir.edu.tr [Physics Department, Science and Literature Faculty, Balikesir University, 10145 Cagis, Balikesir (Turkey); Alper, Mursel, E-mail: malper@uludag.edu.tr [Physics Department, Science and Literature Faculty, Uludag University, 16059 Gorukle, Bursa (Turkey)

    2014-02-15

    Highlights: • Electrodeposited ternary CoFeCu alloy may be a promising alternative of currently used materials. • CoFeCu films were deposited from the electrolytes with different Fe concentrations. • Structure changed from the mixed phase of hcp and fcc to the fcc and finally bcc with increasing Fe. • Needle-like shapes turned to roundish structures with increasing Fe concentration. • Saturation magnetisation increased and coercivity decreased with increasing Fe concentration. -- Abstract: The properties of electrodeposited CoFeCu films were studied with respect to Fe ion concentration in the electrolyte due to their interesting magnetic properties like high saturation magnetisation and low coercivity. The films were characterised in terms of microstructural and magnetic properties. From the compositional analysis, the Fe contents in the films are found to be consistent with the Fe ion concentrations in the electrolytes. With the surface morphology analysis of the films, the number of the roundish shape structures on the surface increased with increasing Fe ion concentration (⩾0.01 M Fe) whereas the CoCu films (0 M Fe) had ridged grains. The crystal structure of the films, examined by X-ray diffraction, changed from the mixed phase of the hexagonal close packed and face centered cubic (fcc) to the fcc and finally body centered cubic structure as the Fe ion concentration in the electrolyte increased from 0 to 0.04 M. And, the average grain size decreased with increasing Fe ion concentration. Magnetisation measurements by vibrating sample magnetometer displayed that the saturation magnetisation increased and the coercivity decreased as the Fe ion concentration increased. Also, it was found that the easy-axis of the magnetisation of films is parallel to the film plane. All films showed anisotropic magnetoresistance. The longitudinal and transverse magnetoresistance magnitudes of the films changed between 3.2–4.0 and 3.0–3.8, respectively. In the study

  3. Methane decomposition on Fe-Cu Raney-type catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, A.F.; Orfao, J.J.M.; Figueiredo, J.L. [Laboratorio de Catalise e Materiais, Laboratorio Associado LSRE/LCM, Departamento de Engenharia Quimica, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)

    2009-10-15

    The decomposition of methane into hydrogen and carbon was studied on Fe-Cu catalysts of Raney-type. The activity of the catalysts was assessed by comparing the experimental conversions with the calculated equilibrium conversions for each set of experimental conditions. The stability of the catalysts was assessed by comparing the maximum conversions with the conversions at the end of 5-hour tests. The carbon deposits obtained consist mostly of carbon nanofibers. Good results were obtained when the Fe-Cu Raney-type systems were thermally treated in situ at 600 C, as a result of incipient alloy formation. These catalysts showed higher stability than the monometallic Raney-Fe catalysts. (author)

  4. Itinerant Magnetism in Metallic CuFe2Ge2

    Science.gov (United States)

    Shanavas, K. V.; Singh, David J.

    2015-01-01

    Theoretical calculations are performed to understand the electronic structure and magnetic properties of CuFe2Ge2. The band structure reveals large electron density N(EF) at the Fermi level suggesting a strong itinerant character of magnetism. The Fermi surface is dominated by two dimensional sheet like structures, with potentially strong nesting between them. The magnetic ground state appears to be ferromagnetic along a and antiferromagnetic in other directions. These results show that CuFe2Ge2 is an antiferromagnetic metal, with similarities to the Fe-based superconductors; such as magnetism with substantial itinerant character and coupling between magnetic order and electrons at the Fermi energy. PMID:25807140

  5. Time evolution of morphology in mechanically alloyed Fe-Cu.

    Science.gov (United States)

    Wille, Catharina G; Al-Kassab, Tala'at; Kirchheim, Reiner

    2011-05-01

    Being widely accessible as well as already utilised in many applications, Fe-Cu acts as an ideal binary model alloy to elaborate the enforced nonequilibrium enhanced solubility in such a solution system that shows a limited regime of miscibility and characterised by a large positive heat of mixing. In addition to the detailed analysis of ball milled Fe-Cu powders by means of Atom Probe Tomography (APT), site specific structural analysis has been performed in this study using Transmission Electron Microscopy (TEM). In this contribution results on powders with low Cu concentrations (2.5-10 at%) are presented. Combining a ductile element (Cu, fcc) and a brittle one (Fe, bcc), striking differences in morphology were expected and found on all length-scales, depending on the mixing ratio of the two elements. However, not only could the atomic mixing of Fe and Cu be evaluated, but also the distribution of impurities, mostly stemming from the fabrication procedure. The combination of APT and TEM enables a correlation between the structural evolution and the chemical mixing during the milling process. For the first time, a clear distinction can be drawn between the morphological evolution at the surface and in the interior of the powder particles. This became possible owing to the site specific sample preparation of TEM lamellae by Focussed Ion Beam (FIB). Surprisingly, the texture arising from the ball milling process can directly be related to the classical rolling texture of cold rolled Fe. In addition, full homogeneity can be achieved even on the nano-scale for this material as shown by APT, resulting in an extended miscibility region in comparison to the equilibrium phase diagram. Grain sizes were determined by means of XRD and TEM. The strain corrected XRD results are in very good agreement with the values derived by TEM, both confirming a truly nanocrystalline structure. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Time evolution of morphology in mechanically alloyed Fe-Cu

    KAUST Repository

    Wille, Catharina Gabriele

    2011-05-01

    Being widely accessible as well as already utilised in many applications, Fe-Cu acts as an ideal binary model alloy to elaborate the enforced nonequilibrium enhanced solubility in such a solution system that shows a limited regime of miscibility and characterised by a large positive heat of mixing. In addition to the detailed analysis of ball milled Fe-Cu powders by means of Atom Probe Tomography (APT), site specific structural analysis has been performed in this study using Transmission Electron Microscopy (TEM).In this contribution results on powders with low Cu concentrations (2.5-10 at%) are presented. Combining a ductile element (Cu, fcc) and a brittle one (Fe, bcc), striking differences in morphology were expected and found on all length-scales, depending on the mixing ratio of the two elements. However, not only could the atomic mixing of Fe and Cu be evaluated, but also the distribution of impurities, mostly stemming from the fabrication procedure. The combination of APT and TEM enables a correlation between the structural evolution and the chemical mixing during the milling process. For the first time, a clear distinction can be drawn between the morphological evolution at the surface and in the interior of the powder particles. This became possible owing to the site specific sample preparation of TEM lamellae by Focussed Ion Beam (FIB). Surprisingly, the texture arising from the ball milling process can directly be related to the classical rolling texture of cold rolled Fe. In addition, full homogeneity can be achieved even on the nano-scale for this material as shown by APT, resulting in an extended miscibility region in comparison to the equilibrium phase diagram. Grain sizes were determined by means of XRD and TEM. The strain corrected XRD results are in very good agreement with the values derived by TEM, both confirming a truly nanocrystalline structure. © 2011 Elsevier B.V.

  7. Dynamical freezing, magnetic ordering, and the magnetocaloric effect in nanostructured Fe/Cu thin films

    Energy Technology Data Exchange (ETDEWEB)

    Desautels, R. D.; Lierop, J. van [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Shueh, C.; Lin, K.-W. [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan (China); Freeland, J. W. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2016-04-25

    Dynamical freezing of Fe nanocrystallites in a Cu matrix with magnetic ordering of an FeCu interfacial phase provides a unique window into the magnetocaloric effect. The FeCu alloy altered the Fe nanocrystallite surface atoms, and with a magnetic ordering temperature comparable to the dynamical freezing temperature of the nanocrystallites enabled Fe surface atoms to contribute to the overall magnetization. Tuning the amount of interfacial alloy resulted in the control of the magnetic ordering temperature and the magnetocaloric properties.

  8. Magnetic properties of Sm-Fe-N bulk magnets produced from Cu-plated Sm-Fe-N powder

    Directory of Open Access Journals (Sweden)

    Tetsuji Saito

    2017-05-01

    Full Text Available In this study, Cu-plated Sm-Fe-N powder was prepared for consolidation by the SPS method. The structures and magnetic properties of Sm-Fe-N bulk magnets produced from the Cu-plated Sm-Fe-N powder were examined. It was found that the powder could be consolidated into bulk materials at low temperatures of 473–673 K. The Sm-Fe-N magnet produced at a temperature of 473K from the Cu-plated Sm-Fe-N powder showed a high coercivity of 9.5 kOe, close to that of the Sm-Fe-N powder.

  9. Rapid thermal annealing of FePt and FePt/Cu thin films

    Energy Technology Data Exchange (ETDEWEB)

    Brombacher, Christoph

    2011-01-10

    Chemically ordered FePt is one of the most promising materials to reach the ultimate limitations in storage density of future magnetic recording devices due to its high uniaxial magnetocrystalline anisotropy and a corrosion resistance superior to rare-earth based magnets. In this study, FePt and FePt/Cu bilayers have been sputter deposited at room temperature onto thermally oxidized silicon wafers, glass substrates and self-assembled arrays of spherical SiO{sub 2} particles with diameters down to 10 nm. Millisecond flash lamp annealing, as well as conventional rapid thermal annealing was employed to induce the phase transformation from the chemically disordered A1 phase into the chemically ordered L1{sub 0} phase. The influence of the annealing temperature, annealing time and the film thickness on the ordering transformation and (001) texture evolution of FePt films with near equiatomic composition was studied. Whereas flash lamp annealed FePt films exhibit a polycrystalline morphology with high chemical L1{sub 0} order, rapid thermal annealing can lead to the formation of chemically ordered FePt films with (001) texture on amorphous SiO{sub 2}/Si substrates. The resultant high perpendicular magnetic anisotropy and large coercivities up to 40 kOe are demonstrated. Simultaneously to the ordering transformation, rapid thermal annealing to temperatures exceeding 600 C leads to a break up of the continuous FePt film into separated islands. This dewetting behavior was utilized to create regular arrays of FePt nanostructures on SiO{sub 2} particle templates with periods down to 50 nm. The addition of Cu improves the (001) texture formation and chemical ordering for annealing temperatures T{sub a} {<=}600 C. In addition, the magnetic anisotropy and the coercivity of the ternary FePtCu alloy can be effectively tailored by adjusting the Cu content. The prospects of FePtCu based exchange spring media, as well as the magnetic properties of FePtCu nanostructures fabricated

  10. Ar+ and CuBr laser-assisted chemical bleaching of teeth: estimation of whiteness degree

    Science.gov (United States)

    Dimitrov, S.; Todorovska, Roumyana; Gizbrecht, Alexander I.; Raychev, L.; Petrov, Lyubomir P.

    2003-11-01

    In this work the results of adaptation of impartial methods for color determination aimed at developing of techniques for estimation of human teeth whiteness degree, sufficiently handy for common use in clinical practice are presented. For approbation and by the way of illustration of the techniques, standards of teeth colors were used as well as model and naturally discolored human teeth treated by two bleaching chemical compositions activated by three light sources each: Ar+ and CuBr lasers, and a standard halogen photopolymerization lamp. Typical reflection and fluorescence spectra of some samples are presented; the samples colors were estimated by a standard computer processing in RGB and B coordinates. The results of the applied spectral and colorimetric techniques are in a good agreement with those of the standard computer processing of the corresponding digital photographs and complies with the visually estimated degree of the teeth whiteness judged according to the standard reference scale commonly used in the aesthetic dentistry.

  11. Mechanical alloying in the Fe-Cu system

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Gente, C.; Bormann, R.

    1998-01-01

    The studies of mechanical alloying on the Fe-Cu system, as a model system for those with positive heats of mixing, are reviewed. Several problems involved in the mechanical alloying process are discussed. For example, (1) whether alloying occurs on an atomic level; (2) what the solid solubility...... in the Fe-Cu system is; (3) where the positive energy is stored in the alloys; (4) what the decomposition process of the supersaturated alloys is; and (5) what type of magnetic properties the new materials have. The elucidation of these problems will shed light on the understanding of the mechanisms...... for the preparation of materials under highly non-equilibrium conditions in systems with positive heats of mixing by mechanical alloying....

  12. Model of Cu-Al-Fe-Ni Bronze Crystallization

    Directory of Open Access Journals (Sweden)

    Pisarek B. P.

    2013-09-01

    Full Text Available According to the analysis of the current state of the knowledge shows that there is little information on the process of phase transformations that occur during the cooling Cu-Al-Fe-Ni hypo-eutectoid bronzes with additions of Cr, Mo and/or W, made additions individually or together, for the determination of: the type of crystallizing phases, crystallizing phases, order and place of their nucleation. On the basis of recorded using thermal and derivative analysis of thermal effects phases crystallization or their systems, analysis of the microstructure formed during crystallization - observed on the metallographic specimen casting ATD10-PŁ probe, analysis of the existing phase equilibrium diagrams forming elements tested Cu-Al-Fe-Ni bronze, with additions of Cr, Mo, W and/or Si developed an original model of crystallization and phase transformation in the solid state, the casting of high quality Cu-Al-Fe-Ni bronze comprising: crystallizing type phase, crystallizing phase sequence, place of nucleation.

  13. Quantum-well states and induced magnetism in Fe/CuN/Fe bcc (001) trilayers

    DEFF Research Database (Denmark)

    Niklasson, A.M.N.; Mirbt, S.; Skriver, Hans Lomholt

    1996-01-01

    profiles of two single Fe/Cu interfaces. The small deviations from this simple superposition are shown to be a consequence of quantum-well states confined within the paramagnetic spacer. This connection is confirmed by direct calculation of the state density. The results are of conceptual interest...

  14. Thermally activated precipitation at deformation-induced defects in Fe-Cu and Fe-Cu-B-N alloys studied by positron annihilation spectroscopy

    NARCIS (Netherlands)

    He, S.M.; Van Dijk, N.H.; Schut, H.; Peekstok, E.R.; Van der Zwaag, S.

    2010-01-01

    We have investigated the influence of deformation-induced defects on the isothermal precipitation at 550?°C in as-quenched (solute-supersaturated) and annealed (solute-depleted) Fe-Cu and Fe-Cu-B-N alloys by positron annihilation spectroscopy and hardness tests. Using the coincidence Doppler

  15. Field-controlled magnetic order in the quantum spin-ladder system (Hpip)2CuBr4

    DEFF Research Database (Denmark)

    Thielemann, B.; Rüegg, C.; Kiefer, K.

    2009-01-01

    Neutron diffraction is used to investigate the field-induced, antiferromagnetically ordered state in the two-leg spin-ladder material (Hpip)(2)CuBr4. This "classical" phase, a consequence of weak interladder coupling, is nevertheless highly unconventional: its properties are influenced strongly b...... the quantum fluctuation corrections to the mean-field interaction....

  16. Magnetochemistry of the tetrahaloferrate(III) ions. 2. Crystal structure and magnetic ordering in (4-Br(py)H) sub 3 Fe sub 2 Cl sub 1. 3 Br sub 7. 7 and (4-Cl(py)H) sub 3 Fe sub 2 Br sub 9. The superexchange paths in the A sub 3 Fe sub 2 X sub 9 salts

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, C.B.; Carlin, R.L.; Schultz, A.J.; Loong, C.K. (Univ. of Illinois, Chicago (USA) Argonne National Lab., IL (USA))

    1990-09-05

    A series of neutron diffraction investigations at 25 K are reported on single crystals of stoichiometry (4-chloropyridinium){sub 3}Fe{sub 2}Br{sub 9} and on (4-bromopyridinium){sub 3}Fe{sub 2}Cl{sub 1.3}Br{sub 7.7}. The compound of stoichiometry (4-bromopyridinium){sub 3}Fe{sub 2}Cl{sub 1.3}Br{sub 7.7} is found to belong to the space group P2{sub 1}/n with four formula units in the unit cell, and the related compound (4-chloropyridinium){sub 3}Fe{sub 2}Bn{sub 9} was found to belong to the same space groups. Structural analysis shows that the iron is present as the (FeX{sub 4}){sup {minus}} ion (X = Cl, Br). The results of the determination of the crystal structure of the compounds are reported. Both materials are isomorphous with the previously reported bis(4-chloropyridinium tetrachloroferrate(III))-4-chloropyridinium chloride. Magnetic measurements on single crystals show that the S = 5/2 material (4-bromopyridinium){sub 3}Fe{sub 2}Cl{sub 1.3}Br{sub 7.7} orders as a canted antiferromagnet at 5.67 K, while (4-chloropyridinium){sub 3}Fe{sub 2}Br{sub 9} orders in a similar fashion at 7.96 K. Magnetic susceptibility data are compared with the theoretical predictions for the simple cubic (sc) Heisenberg high-temperature series expansion model, and superexchange pathways for the isostructural series of monoclinic A{sub 3}Fe{sub 2}X{sub 9} salts are examined. 19 refs., 6 figs., 6 tabs.

  17. Ammonia synthesis on Au modified Fe(111) and Ag and Cu modified Fe(100) surfaces

    DEFF Research Database (Denmark)

    Lytken, Ole; Waltenburg, Hanne Neergaard; Chorkendorff, Ib

    2003-01-01

    and a high-pressure cell. Ammonia was synthesized from a stoichiometric (N-2:3H(2)) gas mixture at a pressure of 2 bar. By deposition of small amounts of An, the ammonia production activity of the Fe(1 1 1) surface can be enhanced. More important, for the gold modified surface, the reaction order in ammonia...... to lifting of the nitrogen induced reconstruction of the Fe(I 11). On the Fe(l 00) surface strong effects were expected from modification with Cu and Ag since the in general more reactive atomic steps always present on such surfaces would be blocked. However, only minor and modest negative effects were found....... The Cu and Ag were found to be inefficient step blockers as they were forced away from the surface by the formation of the much more stable surface nitrogen....

  18. Structural and room-temperature ferromagnetic properties of Fe-doped CuO nanocrystals

    Science.gov (United States)

    Li, Youxia; Xu, Mei; Pan, Liqing; Zhang, Yaping; Guo, Zhengang; Bi, Chong

    2010-06-01

    Fe-doped CuO (Cu1-xFexO) nanocrystals (NCs) (x =0, 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, and 0.3) are prepared by using the urea nitrate combustion method. X-ray diffraction (XRD) analysis confirmed the monoclinic structure of CuO. Single-phase structure is obtained for the 0%-20% Fe-doped CuO, whereas for the 25% and 30% Fe-doped CuO material, secondary phase, α-Fe2O3, is presented. Rietveld refinements of XRD data revealed that with an increase in Fe doping level, there is a monotonic increase in cation vacancies in the Fe-doped samples. X-ray photoelectron spectroscopy measurements on the Cu0.98Fe0.02O sample revealed that the Cu2+ sites are partly substituted by Fe3+ ions. The microstructure is investigated by high-resolution transmission electron microscopy. The magnetic hysteresis loops and the temperature dependence of magnetization of the samples indicated that the samples are mictomagnetic of ferromagnetic domains originated from ferromagnetic coupling between the doping Fe ions in Cu1-xFexO NCs randomly distributed in the antiferromagnetic CuO matrix. The Curie temperature of the ferromagnetic phase is higher than 400 K for all Fe-doped CuO samples. The ferromagnetic behavior of the samples is discussed.

  19. Ultrafast demagnetization, spin-dependent Seebeck effect, and thermal spin transfer torque in Pt/TbFe/Cu and Pt/TbFe/Cu/Fe thin films

    Science.gov (United States)

    Kimling, Johannes; Hebler, Birgit; Kimling, Judith; Albrecht, Manfred; Cahill, David G.

    We investigate diffusive spin currents in Pt(20nm)/TbFe(10nm)/Cu(100nm) and Pt(20 nm)/TbFe(10nm)/ Cu(100nm)/Fe(3nm) stacks using time-resolved magneto-optic Kerr effect (TRMOKE) and time-domain thermoreflectance measurements. Our experiments are based on two hypothesis: (1) fast changes of magnetization due to laser excitation are transferred into spin accumulation, e.g., via electron-magnon scattering; the generated spin accumulation drives a diffusive spin current into adjacent normal metal layers; (2) electronic thermal transport through the ferromagnetic layer injects a spin current into adjacent normal metal layers, based on the spin-dependent Seebeck effect. We excite the Pt layer with ps-laser pulses. Resulting diffusive spin currents generate nonequilibrium magnetization in the Cu layer (sample I) and induce a precession of the magnetization of the Fe layer via spin transfer torque (sample II). Both responses are probed using TRMOKE. Prior experiments used [Co(0.2nm)/Pt(0.4nm)]x5/Co(0.2nm) instead of TbFe. The ferrimagnetic TbFe layer with introduces two major modifications: (1) slow demagnetization behavior, and (2) large thermal resistance. Hence, thermal spin transfer torques can be observed on significantly longer time scales. Financial support by the German Research Foundation under DFG-Grant No. KI 1893/1-1 and DFG-Grant No. AL 618/21-1 are kindly acknowledged.

  20. In situ TEM observation of novel chemical evolution of MnBr2 catalyzed by Cu under electron beam irradiation

    Science.gov (United States)

    Wang, Wei; Bai, Xianwei; Guan, Xiangxiang; Shen, Xi; Yao, Yuan; Wang, Yanguo; Zou, Bingsuo; Yu, Richeng

    2017-10-01

    Manganese bromide has attracted enormous attention for its applications in the syntheses of organic-inorganic hybrid compounds. A complete understanding of structural and chemical stabilities of MnBr2 is important for controlling its properties. Here, we focus on the irradiation resistance of MnBr2. The chief purpose of this research is reached by in situ transmission electron microscopy. It is demonstrated that the deliquescent MnBr2 powder is prone to adsorb the vapor in air, and the hydrous MnBr2 can be decomposed under its continuous exposure to electron beam, indicated by a transmission electron microscope via the catalysis of Cu grid at room temperature.

  1. CoFe Layers Thickness and Annealing Effect on the Magnetic Behavior of the CoFe/Cu Multilayer Nanowires

    Directory of Open Access Journals (Sweden)

    M. Ahmadzadeh

    2015-04-01

    Full Text Available CoFe/Cu multilayer nanowires were electrodeposited into anodic aluminum oxide templates prepared by a two-step mild anodization method, using the single-bath technique. Nanowires with 30 nm diameter and the definite lengths were obtained. The effect of CoFe layers thickness and annealing on the magnetic behavior of the multilayer nanowires was investigated. The layers thickness was controlled through the pulses numbers: 200, 260, 310,360 and 410 pulses were used to deposit the CoFe layers, while 300 pulse for the Cu layers. A certain increase in coercivity and squareness of CoFe/Cu multilayer nanowires observed with increasing the CoFe layer thickness and annealing improved the coercivity and decrease squareness of CoFe/Cu multilayer nanowires. First order reversal curves after annealed showed amount domains with soft magnetic phase, it also shows decreasing spreading of distribution function along the Hu axis after annealed

  2. Three novel Cu6S6 cluster-based coordination compounds: synthesis, framework modulation and the sensing of small molecules and Fe(3+) ions.

    Science.gov (United States)

    Song, Jiang-Feng; Li, Si-Zhe; Zhou, Rui-Sha; Shao, Jia; Qiu, Xiao-Min; Jia, Ying-Ying; Wang, Jun; Zhang, Xiao

    2016-08-07

    Three novel Cu6S6 cluster-based coordination compounds formulated as [Cu(mpymt)3]2 (1), {(CuBr4)[Cu(mpymt)6]}n (2), and {(CuI6)[Cu(mpymt)6]}n (3) (Hmpymt = 4-methylpyrimidine-2-thione), have been synthesized under solvothermal conditions and characterized by elemental analysis, infrared (IR) spectroscopy, thermal gravimetric analysis, powder X-ray diffraction and single-crystal X-ray diffraction. Structural analysis reveals that compound 1 shows a distorted octahedral core of six copper atoms (Cu6S6) constructed from four α and two β type N[double bond, length as m-dash]C-SH parts from six mpymt(-) anions. Compound 2 displays an interesting 3D framework constructed from Cu6S6 and Cu4Br4 Cu(i) clusters simultaneously, interestingly, six mpymt(-) with α type N[double bond, length as m-dash]C-SH parts are involved in the formation of Cu6S6. Compound 3 displays an infinite 1D framework constructed from Cu6S6 and Cu6I6 Cu(i) clusters, notably, four α and two β type N[double bond, length as m-dash]C-SH parts are involved in the formation of the Cu6S6 cluster, however, only mpymt(-) ligands containing α type N[double bond, length as m-dash]C-SH parts form the bridged Cu6I6 cluster. The experimental results reveal that halogen ions finely modulate the structural features of compounds 1-3. The fluorescent properties of compounds 1-3 in the solid state and in various solvent emulsions were investigated in detail, the results of which indicate that compounds 1-3 are all highly sensitive naked eye colorimetric sensors for NB, 2-NT and Fe(3+) (NB = nitrobenzene and 2-NT = 2-nitrotoluene).

  3. Evaluation of Fe and Zn/Cu ratio in serum of patients with sickle cell anemia by total reflection X-ray fluorescence using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Canellas, Catarine G.L.; Leitao, Roberta G.; Lopes, Ricardo T., E-mail: catarine@lin.ufrj.b, E-mail: ricardo@lin.ufrj.b [Universidade Federal do Rio de Janeiro (PEN/COPPE/UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia. Programa de Engenharia Nuclear. Lab. de Instrumentaco Nuclear; Carvalho, Silvia M.F., E-mail: silvia@hemorio.rj.gov.b [State Institute of Hematology Arthur de Siqueira Cavalcanti (HEMORIO), Rio de Janeiro, RJ (Brazil); Bellido, Alfredo Victor B., E-mail: alfredo@ien.gov.b [Federal Fluminense University (UFF), Niteroi, RJ (Brazil). Chemistry Inst.; Anjos, Marcelino J., E-mail: marcelin@lin.ufrj.b [State University of Rio de Janeiro (UERJ), RJ (Brazil). Physics Inst.

    2011-07-01

    Sickle cell anemia (SCA) is a blood disorder that affects hemoglobin, the protein found in red blood cells that help carry oxygen throughout the body. In this work we have analyzed serum samples from patients with SCA by using total reflection X-ray fluorescence using synchrotron radiation (SRTXRF). The SRTXRF measurements were performed at the X-ray fluorescence beamline at Brazilian National Synchrotron Light Laboratory (LNLS), in Campinas, Sao Paulo using a polychromatic beam. We have studied forty-three patients aged 18-50 years old, suffering from SCA and Sixty healthy volunteers aged 18-60 years old. It was possible to determine the concentrations of the following elements: P, S, Cl, K, Ca, Fe, Cu, Zn, Br and Rb. Student's t-test was applied in order to check whether the two populations (CG x SCA) had the same mean values. It was observed that elemental concentration of P, Cl, K, Fe, Cu, Zn and Br differed significantly ({alpha} = 0.05) between groups of healthy subjects and SCA. The concentrations of K, Fe and Cu in the serum samples of patients with SCA were larger 15%, 120 % and 20 %, respectively, when compared with the CG. On the other hand, the concentrations of P (-20 %), Cl (-6 %), Zn (-25 %) and Br (-22 %) were smaller than the values determined for the control group. The serum level Cu/Zn ratio was significantly higher (60%) in the serum samples of patients with SCA group than the CG. So, the Cu/Zn ratio can be used as an adjuvant index in enhancement for diagnosis of SCA. There are evidences of an association among Fe, Cu, Zn and Cu/Zn in the SCA pathogenesis process. (author)

  4. Cu(I Modification during γ-Fe2O3 Nanoparticles Synthesis and Subsequent Characterization

    Directory of Open Access Journals (Sweden)

    Hong Mao

    2015-01-01

    Full Text Available During the synthesis of the γ-Fe2O3 nanoparticles via the chemically induced transition method, Cu(I modification has been attempted by adding CuCl/NaOH to the treatment solution. The experimental results showed that, under the condition of a NaOH content equal to 0.04 moles, when the content of CuCl is as low as 1.25×10-3 or 2.50×10-3 moles, the products are single γ-Fe2O3/Cu(IFeO2/FeCl3·6H2O composite nanoparticles, whereas when the content of CuCl is higher, 5×10-2 moles, the product is a mixture consisting of γ-Fe2O3/Cu(IFeO2/FeCl3·6H2O nanoparticles and Cu(II(OHCl nanoparticles. For the γ-Fe2O3/Cu(IFeO2/FeCl3·6H2O composite nanoparticles, the Cu(IFeO2 interface layer is not thick enough to form one unit cell, but it can modify the formation of a FeCl3·6H2O surface layer and the effective magnetization of the γ-Fe2O3 core.

  5. Synthesis and characterization of CuFeO2+d delafossite powders

    OpenAIRE

    Mugnier, Emmanuelle; Barnabé, Antoine; Tailhades, Philippe

    2006-01-01

    Effects of oxygen off-stoichiometry have been investigated on CuFeO2+d delafossite-type powders prepared by solid state reaction. Materials annealed at different temperatures under air atmosphere were compared. Thermogravimetric analysis coupled with X-ray structural analysis showed that a powdered CuFeO2 can be oxidized up to CuFeO2+d with d =0.18. Electrical measurements confirm the existence of oxidized CuFeO2+d phases. Particular attention is paid to the correlation between oxidation proc...

  6. Calcium alginate encapsulated Ni/Fe nanoparticles beads for simultaneous removal of Cu (II) and monochlorobenzene.

    Science.gov (United States)

    Kuang, Ye; Du, Jianhua; Zhou, Rongbing; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra

    2015-06-01

    Calcium alginate encapsulated Ni/Fe bimetallic nanoparticles beads (CA-Ni/Fe beads) were synthesized to simultaneously remove Cu (II) and monochlorobenzene (MCB) from aqueous solution. SEM, EDS, and XRD analyses confirmed that Ni/Fe bimetallic nanoparticles were not oxidized and successfully encapsulated by calcium alginate (CA). The experiments showed that the encapsulation process improved the simultaneous removal efficiency of Cu (II) and MCB, from 83.9% to 86.7% for Cu (II) and 94.7% to 99.1% for MCB compared with bare Ni/Fe nanoparticles after 120min treatment. Furthermore, the removal efficiency of Cu (II) and MCB increased with higher temperature, calcium alginate: Ni/Fe ratios and pH. Pseudo-second-order model for adsorption and pseudo-first-order model for the reduction process fitted the simultaneous removal of Cu (II) and MCB using CA-Ni/Fe beads. Based on the above results, it could be concluded that the simultaneous removal was a two-step process: firstly, the adsorption of Cu (II) and MCB on the CA-Ni/Fe beads; and secondly, reduction of Cu (II) and dehalogenation of MCB by Ni/Fe in CA-Ni/Fe beads. Finally, the efficiency of regenerated CA-Ni/Fe beads was tested using synthesized wastewater which showed a satisfactory removal efficiency of Cu (II) and MCB maintained at 83.8% and 91.7% after three times' regeneration. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Magnetism of CuCl2·2D2O and CuCl2·2H2O, and of CuBr2·6H2O

    Science.gov (United States)

    DeFotis, G. C.; Hampton, A. S.; Van Dongen, M. J.; Komatsu, C. H.; Benday, N. S.; Davis, C. M.; Hays, K.; Wagner, M. J.

    2017-07-01

    The magnetic properties of little examined CuCl2·2D2O are studied and compared with those of CuCl2·2H2O. New CuBr2·6H2O is also examined. Susceptibility maxima appear for chlorides at 5.35 and 5.50 K, in the above order, with estimated antiferromagnetic ordering at 4.15 and 4.25 K. Curie-Weiss fits yield g of 2.210 and 2.205, and Weiss θ of -6.0 and -4.7 K, respectively, in χM = C/(T - θ). One-dimensional Heisenberg model fits to susceptibilities, including interchain exchange in a mean-field approximation, are performed. Interchain exchange is significant but much weaker than intrachain. The bromide hexahydrate strongly differs magnetically from any chloride hydrate, but exhibits notable similarities and differences compared to previously studied CuBr2. A broad susceptibility maximum occurs near 218 K, only 4% lower than for CuBr2, but with almost twice the magnitude. Powder X-ray diffraction data for CuBr2·6H2O may be best accounted for by a monoclinic unit cell that is metrically orthorhombic. The volume per formula unit is consistent with trends in metal ionic radii. However, an alternative monoclinic cell with 5% smaller volume more readily rationalizes the magnetism.

  8. Study of the evolution of the hyperfine parameters in nanostructured Fe-Mn-Cu system

    Energy Technology Data Exchange (ETDEWEB)

    Mizrahi, M., E-mail: mizrahi@fisica.unlp.edu.ar; Cabrera, A. F.; Desimoni, J. [Facultad de Ciencias Exactas UNLP, Departamento de Fisica (Argentina)

    2007-09-15

    Hyperfine parameters evolution with the Cu content obtained by Moessbauer spectroscopy from mechanical milled (Fe{sub 79}Mn{sub 21}){sub 1-x}Cu{sub x} (x = 0.00 to 0.30) are presented. Results indicate that the Cu addition favors the formation of a FCC phase with two different magnetic states at room temperature. The trend of the hyperfine parameters with Cu composition suggests the incorporation of the Cu atoms at the regular FCC lattice sites.

  9. Theory of singlet-ground-state magnetism. Application to field-induced transitions in CsFeCl3 and CsFeBr3

    DEFF Research Database (Denmark)

    Lindgård, P.-A.; Schmid, B.

    1993-01-01

    In the singlet ground-state systems CsFeCl3 and CsFeBr3 a large single-ion anisotropy causes a singlet ground state and a doubly degenerate doublet as the first excited states of the Fe2+ ion. In addition the magneteic interaction is anisotropic being much larger along the z axis than perpendicular...... to it. Therefore, these quasi-one-dimensional magnetic model systems are ideal to demonstrate unique correlation effects. Within the framework of the correlation theory we derive the expressions for the excitation spectrum. When a magnetic field is applied parallel to the z axis both substances have...

  10. Rapid removal of ultra-high-concentration p-nitrophenol in aqueous solution by microwave-enhanced Fe/Cu bimetallic particle (MW-Fe/Cu) system.

    Science.gov (United States)

    Ren, Yi; Zhou, Jinfan; Pan, Zhicheng; Lai, Bo; Yuan, Donghai

    2017-10-10

    Ultra-high-concentration PNP-contained wastewaters are produced sometimes due to the wide application of this nitrophenolic compound in the chemical industry. However, there is a lack of appropriate technologies to rapidly pretreat the ultra-high-concentration wastewater. Therefore, a new microwave-enhanced Fe/Cu bimetallic particles (MW-Fe/Cu) system was developed to rapidly remove ultra-high-concentration PNP. First, the priority of the determinative parameters was obtained by orthogonal experiment. Based on this result, the effects of initial pH, microwave power, Fe/Cu dosage and initial PNP concentration on PNP removal were optimized thoroughly. Under the optimal conditions (i.e. initial pH = 1.0, MW power = 385 W, Fe/Cu dosage = 30 g/L and initial PNP concentration = 4000 mg/L), four control treatment systems (i.e. MW-Fe(0), heating-Fe/Cu, MW alone and Fe/Cu alone system) were set up to compare with the MW-Fe/Cu system. The results suggest that high PNP removal (more than 99% with 2.5 min, k1/k2 = 1.18/6.91 min(-1)) and COD removal (26.6% with 5 min treatment) could be obtained by the MW-Fe/Cu system, which were much superior to those obtained using the MW-Fe(0) (k1/k2 = 0.62/2.21 min(-1)) and the heating-Fe/Cu system (k1/k2 = 0.53/1.52 min(-1)). Finally, the determination of the intermediates of PNP degradation by HPLC indicated that the MW assistance process did not change the degradation pathway of PNP. This concludes that the new MW-Fe/Cu system was the promising technology for pretreatment of wastewater containing ultra-high-concentration toxic and refractory pollutants at a fairly short treatment time.

  11. Kinetic study of the annealing reactions in Cu-Ni-Fe alloys; Estudio cinetico de las reacciones de recocido en aleaciones de Cu-Ni-Fe

    Energy Technology Data Exchange (ETDEWEB)

    Donoso, E.

    2014-07-01

    The thermal aging of a Cu-45Ni-4Fe, Cu-34Ni-11Fe and Cu-33Ni-22Fe alloys tempered from 1173 K have been studied from Differential Scanning Calorimetry (DSC) and microhardness measurements. The analysis of DSC curves, from room temperature to 950 K, shows the presence of one exothermic reaction associated to the formation of FeNi{sub 3} phase nucleating from a modulate structure, and one endothermic peak attributed to dissolution of this phase. Kinetic parameters were obtained using the usual Avrami-Erofeev equation, modified Kissinger method and integrated kinetic functions. Microhardness measurements confirmed the formation and dissolution of the FeNi{sub 3} phase. (Author)

  12. Pulsed Laser Deposition Growth of Delafossite (CuFeO2) thin films and multilayers

    Science.gov (United States)

    Joshi, Toyanath; Ferrari, Piero; Borisov, Pavel; Cabrera, Alejandro; Lederman, David

    2014-03-01

    Owing to its narrow band gap (delafossite CuFeO2 is attractive for applications in the field of solar energy conversion. Obtaining pure phase CuFeO2 thin films, however, is relatively difficult. It is necessary to maintain the lowest possible Cu valency (+1) in order to avoid forming the comparably stable spinel compound CuFe2O4. We present a systematic study of the pulsed laser deposition (PLD) growth conditions for epitaxial (00.1) oriented CuFeO2 thin films on Al2O3 (00.1) substrates. The secondary impurity phase, CuFe2O4, was removed completely by optimizing the growth conditions. RHEED, XRD and TEM showed that the pure phase delafossite films are highly epitaxial to the substrate. The chemical purity was verified by Raman and XPS. The indirect bandgap of 1.15 eV was measured using infrared reflectivity, and is in agreement with the CuFeO2 bulk value. Finally, we discuss the growth and structural characterization of delafossite multilayers, CuFeO2/CuGaO2. This work was supported by a Research Challenge Grant from the West Virginia Higher Education Policy Commission (HEPC.dsr.12.29) and the Microelectronics Advanced Research Corporation (Contract # 2013-MA-2382) at WVU.

  13. Synthesis of Bimetal Fe and Cu Altered TUD-1: A Mesoporous Catalyst for Phenol Hydroxylation Reaction.

    Science.gov (United States)

    Pachamuthu, Muthusamy Poomalai; Subhapriya, Pushparaju

    2018-04-01

    Fe and Cu ions incorporated (Si/Cu = 50, Si/Fe = 50 and Si/Cu + Fe = 50) amorphous, wormhole structured mesoporous catalysts (CuTUD-1, FeTUD-1 and FeCuTUD-1) (TUD-1-Technische Universiteit Delft) have been synthesized hydrothermally using low cost, non-surfactant template triethanolamine (TEA). Physicochemical properties of the catalysts were made using X-ray diffraction (XRD), Nitrogen sorption, FT-IR, DRS UV Visible, FT Raman, SEM, TEM and TG-DTG techniques. The results showed that the materials possess mesoporous, foam type morphology, surface area 485-634 m2/g, pore size 4.8-6.8 nm, pore volume 0.67-0.83 cm3/g and metal ions (Cu2+ and Fe3+) coordinative environment. The highly dispersed Cu2+ and Fe3+ active sites are observed in FeCuTUD-1 catalyst. Also, the synthesized catalysts are tested in the oxidation of phenol with hydrogen peroxide (H2O2) oxidant. Further, reaction parameters such as time, temperature, and catalyst were also investigated.

  14. Compressibility of nanostructured Fe-Cu materials prepared by mechanical milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Olsen, J.S.; Gerward, Leif

    1999-01-01

    The compressibility of nanostructured Fe-Cu materials prepared by mechanical milling has been investigated by in-situ high-pressure x-ray diffraction using synchrotron radiation. It is found that the bulk modulus of both fcc-Cu and bcc-Fe phases decreases with decreasing grain sizes. The unstable...

  15. Room temperature deposition of amorphous p-type CuFeO2 and ...

    Indian Academy of Sciences (India)

    XPS analysis convinced that the chemical state of Cu + and Fe 3 + in the film, and the chemical composition of the thin films is close to the stoichiometry of CuFeO 2 . Surface morphology of the film was analysed by SEM studies. p-type nature and concentration of carriers was investigated by Hall effect measurement.

  16. Short-range Ferromagnetism in Alloy Ribbons of Fe-Cr-Si-Nb-(Ag, Cu)

    DEFF Research Database (Denmark)

    Thanh, P. Q.; Hoa, N. Q.; Chau, N.

    2014-01-01

    We have studied the magnetic properties of two amorphous alloy ribbons Fe72Cr6Si4Nb5B12Ag1 (FCSNB-Ag) and Fe72Cr6Si4Nb5B12Cu1 (FCSNB-Cu), prepared by using a melt-spinning technique. Magnetization (M) measurements for various temperatures (T) and magnetic fields (H) indicate that ferromagnetic...

  17. High Temperature Magnetic Properties of Indirect Exchange Spring FePt/M(Cu,C/Fe Trilayer Thin Films

    Directory of Open Access Journals (Sweden)

    Anabil Gayen

    2013-01-01

    Full Text Available We report the investigation of temperature dependent magnetic properties of FePt and FePt(30/M(Cu,C/Fe(5 trilayer thin films prepared by using magnetron sputtering technique at ambient temperature and postannealed at different temperatures. L10 ordering, hard magnetic properties, and thermal stability of FePt films are improved with increasing postannealing temperature. In FePt/M/Fe trilayer, the formation of interlayer exchange coupling between magnetic layers depends on interlayer materials and interface morphology. In FePt/C/Fe trilayer, when the C interlayer thickness was about 0.5 nm, a strong interlayer exchange coupling between hard and soft layers was achieved, and saturation magnetization was enhanced considerably after using interlayer exchange coupling with Fe. In addition, incoherent magnetization reversal process observed in FePt/Fe films changes into coherent switching process in FePt/C/Fe films giving rise to a single hysteresis loop. High temperature magnetic studies up to 573 K reveal that the effective reduction in the coercivity decreases largely from 34 Oe/K for FePt/Fe film to 13 Oe/K for FePt/C(0.5/Fe film demonstrating that the interlayer exchange coupling seems to be a promising approach to improve the stability of hard magnetic properties at high temperatures, which is suitable for high-performance magnets and thermally assisted magnetic recording media.

  18. Selectivity of nanocavities and dislocations for gettering of Cu and Fe in silicon

    Science.gov (United States)

    Stritzker, B.; Petravic, M.; Wong-Leung, J.; Williams, J. S.

    2001-04-01

    The selectivity of interstitial-based extended defects (loops) and nanocavities for the gettering of Cu and Fe in Si has been studied. Controlled amounts of Cu and Fe were introduced by ion implantation into wafers containing pre-existing nanocavities and/or dislocations. Results show that Cu has a strong preference for gettering to open volume defects, even when high concentrations of interstitial-based loops are present in close proximity. However, the gettering of Fe in samples containing both vacancy- and interstitial-type defects is more complex, with Fe accumulation at all regions in the sample which contain defects, whether they are vacancy- or interstitial-like in character.

  19. On the concentration and separation of the trace-elements fe, cu, zn, mn, pb, mo and co : Paper chromatography

    NARCIS (Netherlands)

    Erkelens, P.C. van

    1961-01-01

    Paper chromatographic separations are described by which the minor constituents of biological ashes are separated either into: (Pb) - Mn - Co - (Pb) - Cu - Fe, Mo, Zn; or into: Cu, Mn, Co - Pb - Fe - Mo - Zn.

  20. Orbital topology, interlayer spin coupling, and magnetic anisotropy of the CuFeO2 compound

    NARCIS (Netherlands)

    Malvestuto, M.; Bondino, F.; Magnano, E.; Lummen, T. T. A.; van Loosdrecht, P. H. M.; Parmigiani, F.

    2011-01-01

    X-ray absorption spectroscopy performed on a CuFeO2 single crystal reveals the pivotal role of the Cu ions in the discussion of the anisotropic properties of the compound. In particular, it is shown that there is a 3d hole density on the nominal 3d(10) Cu+ ions which may lie at the origin of the

  1. Visible-light-driven Ag/AgBr/ZnFe2O4composites with excellent photocatalytic activity for E. coli disinfection and organic pollutant degradation.

    Science.gov (United States)

    Xu, Yuanguo; Liu, Qingqing; Liu, Chenchen; Zhai, Yunpeng; Xie, Meng; Huang, Liying; Xu, Hui; Li, Huaming; Jing, Junjie

    2018-02-15

    Visible-light-driven (VLD) Ag/AgBr/ZnFe 2 O 4 composites with different weight ratios of ZnFe 2 O 4 were synthesized via a facile hydrothermal method. The ZnFe 2 O 4 was evenly dispersed on the surface of Ag/AgBr particles with the diameter about 20 nm. The obtained Ag/AgBr/ZnFe 2 O 4 composites exhibited the high bacterial disinfection efficiency and inactivated bacteria after 120 min visible illumination, which was better than those of with pure ZnFe 2 O 4 and Ag/AgBr. Due to the introduction of ZnFe 2 O 4 , the Ag/AgBr/ZnFe 2 O 4 inactivated bacterial cells through the generation of H 2 O 2 , which generated from the electron reduction on the conduction band of ZnFe 2 O 4 in the system. The photocatalytic experiments indicated that as-prepared samples showed the good photocatalytic performance toward degradation of methyl orange (MO) dye. In a word, the Ag/AgBr/ZnFe 2 O 4 composites, as the antibacterial photocatalyst, is a promising candidate material in wastewater decontamination. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Transparent conductive CuFeO2 thin films prepared by sol-gel processing

    Science.gov (United States)

    Chen, Hong-Ying; Wu, Jia-Hao

    2012-03-01

    In this study, transparent conductive CuFeO2 thin films were deposited onto a quartz substrate using a low-cost sol-gel process and sequential annealing in N2. The sol-gel derived films were annealed at 500 °C for 1 h in air and then annealed at 700 °C in N2 for 2 h. The CuO and CuFe2O4 phases appeared as the film annealed in air, and a single CuFeO2 phase (delafossite, R3m) appeared as the film annealed in N2. X-ray photoelectron spectroscopy showed that the chemical composition of the CuFeO2 thin films was similar to the stoichiometry. The optical bandgap of the CuFeO2 thin films was 3.1 eV. The p-type characteristics of the films were verified by Hall-effect measurements. The electrical conductivity and carrier concentration of the CuFeO2 thin films were 0.358 S cm-1 and 5.34 × 1018 cm-3, respectively. These results show that the proposed low-cost sol-gel process provides a feasible method of depositing transparent CuFeO2 thin films.

  3. Synthesis and Highly Photocatalytic Properties of Cu/Fe3O4 Nanospheres and Nanoparticles

    Science.gov (United States)

    Pan, Lu; Tian, Dong; Zhu, Qiyong

    2017-09-01

    Cu/Fe3O4 nanospheres and nanoparticles were synthesized by using a hydrothermal procedure. The as-prepared samples were characterized by x-ray diffraction, transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy, respectively. The TEM images showed that the morphologies of Cu/Fe3O4 composites could be tuned by adding different amounts of urea. The resultant Cu/Fe3O4 composites could be nanospheres with a mean size of 90 nm with the addition of 15 mmol of urea but nanoparticles with a mean size of about 15 nm by adding 30 mmol of urea. The possible formation mechanism of Cu/Fe3O4 nanospheres and nanoparticles were explained reasonably. The photocatalytic performances of Cu/Fe3O4 composites for degrading methyl blue under irradiation of visible light were investigated. The results demonstrated that Cu/Fe3O4 nanospheres exhibited higher photocatalytic activity than did nanoparticles as they had the same compositions. Additionally, the Cu/Fe3O4 composites with a high Cu content could exhibit higher photocatalytic performance.

  4. ACTIVITY AND PRESSURE OF MAGNESIUM STEAM IN ALLOYS Ni-Mg-Si-Fe and Cu-Mg-Si-Fe

    Directory of Open Access Journals (Sweden)

    V. N. Vlasov

    2010-01-01

    Full Text Available The calculation of activity and pressure of magnesium vapour in melts Ni-Si-Mg-Fe and Cu-Si-Mg-Fe in metal systems at constant magnesium contents 6, 10, 14 и 18 mas.% and temperatures 1350 and 1450 °С is carried out in this work.

  5. Magnetic behavior of as-deposited and annealed CoFe and CoFeCu nanowire arrays by ac-pulse electrodeposition

    Science.gov (United States)

    Ramazani, A.; Almasi-Kashi, M.; Golafshan, E.; Arefpour, M.

    2014-09-01

    CoFe and CoFeCu self-organized alloy nanowires were grown into anodic aluminum oxide template by potentiostatic mode of ac-pulse electrodeposition technique and subsequently annealed at 580 °C. The influence of bath composition, off-time between pulses and annealing treatment on the Cu content, microstructure and magnetic properties of CoFeCu nanowire arrays have been discussed. Increasing the off-time between pulses decreased the coercivity and saturation magnetization of the CoFeCu nanowires due to substitution of Co and Fe with Cu atoms which resulted in electroless process. Coercivity and squareness of the annealed samples increased due to improvement of samples crystallinity. Magnetic measurements showed high perpendicular magnetic anisotropy of the nanowires with easy axis parallel to nanowires axis. X-ray diffraction results indicated that annealed CoFeCu nanowires were polycrystalline with two distinct CoFe and Cu phases.

  6. A GREEN CHEMISTRY APPROACH TO PREPARATION OF CORE (FE OR CU)-SHELL (NOBLE METALS) NANOCOMPOSITES USING AQUEOUS ASCORBIC ACID

    Science.gov (United States)

    A greener method to fabricate novel core (Fe or Cu)-shell (noble metals) nanocomposites of transition metals such as Fe and Cu and noble metals such as Au, Pt, Pd, and Ag using aqueous ascorbic acid is described. Transition metal salts such as Cu and Fe were reduced using ascor...

  7. The important role of polyvinylpyrrolidone and Cu on enhancing dechlorination of 2,4-dichlorophenol by Cu/Fe nanoparticles: Performance and mechanism study

    Science.gov (United States)

    Fang, Liping; Xu, Cuihong; Zhang, Wenbin; Huang, Li-Zhi

    2018-03-01

    The important role of polyvinylpyrrolidone (PVP) and Cu on the reductive dechlorination of 2,4-dichlorophenol (2,4-DCP) by Cu/Fe bimetal nanoparticles has been investigated. The synthesized PVP coated Cu/Fe bimetal nanoparticles with different Cu/Fe ratios were systematically characterized by FTIR, XRD, TEM and magnetic hysteresis loops. The Cu/Fe ratio and the PVP loading were optimized for dechlorination performance, and the optimum ratio of PVP to Cu/Fe was found to be 0.35 and the content of Cu in Cu/Fe nanoparticles was 41%. The presence of PVP as a dispersant/stabilizer results in a highly-dispersed Cu/Fe NPs and increase the reactivity of Cu/Fe NPs for 2,4-DCP removal. The dechlorination rate was enhanced at lower pH and higher temperature conditions. The presence of humic acid, PO43-, NO3-, SO42- leads to a slightly decreased removal efficiency of 2,4-DCP. The magnetic property of PVP-Cu/Fe nanoparticles allows rapid magnetic separation of the catalysts after reaction. A galvanic corrosion model was proposed where iron corrodes and transfers electrons to Cu-rich catalytic regions of the nanoparticles, and finally accelerating the reduction efficiency of 2,4-DCP.

  8. Aqueous copper-mediated living polymerization: exploiting rapid disproportionation of CuBr with Me6TREN.

    Science.gov (United States)

    Zhang, Qiang; Wilson, Paul; Li, Zaidong; McHale, Ronan; Godfrey, Jamie; Anastasaki, Athina; Waldron, Christopher; Haddleton, David M

    2013-05-15

    A new approach to perform single-electron transfer living radical polymerization (SET-LRP) in water is described. The key step in this process is to allow full disproportionation of CuBr/Me6TREN (TREN = tris(dimethylamino)ethyl amine to Cu(0) powder and CuBr2 in water prior to addition of both monomer and initiator. This provides an extremely powerful tool for the synthesis of functional water-soluble polymers with controlled chain length and narrow molecular weight distributions (polydispersity index approximately 1.10), including poly(N-isopropylacrylamide), N,N-dimethylacrylamide, poly(ethylene glycol) acrylate, 2-hydroxyethyl acrylate (HEA), and an acrylamido glyco monomer. The polymerizations are performed at or below ambient temperature with quantitative conversions attained in minutes. Polymers have high chain end fidelity capable of undergoing chain extensions to full conversion or multiblock copolymerization via iterative monomer addition after full conversion. Activator generated by electron transfer atom transfer radical polymerization of N-isopropylacrylamide in water was also conducted as a comparison with the SET-LRP system. This shows that the addition sequence of l-ascorbic acid is crucial in determining the onset of disproportionation, or otherwise. Finally, this robust technique was applied to polymerizations under biologically relevant conditions (PBS buffer) and a complex ethanol/water mixture (tequila).

  9. Synthesis, crystal structures, and photoluminescent properties of the Cu(I)/X/alpha,omega-bis(benzotriazole)alkane hybrid family (X = Cl, Br, I, and CN).

    Science.gov (United States)

    Hu, Man-Cheng; Wang, Yan; Zhai, Quan-Guo; Li, Shu-Ni; Jiang, Yu-Cheng; Zhang, Yong

    2009-02-16

    This work focused on a systematic investigation of the influences of the spacer length of the flexible alpha,omega-bis(benzotriazole)alkane ligands and counteranions on the overall molecular architectures of hybrid structures that include Cu(I). Using the self-assembly of CuX (X = Cl, Br, I, or CN) with the five structurally related flexible organic ligands (L1-L5) under hydro(solvo)thermal conditions, we have synthesized and characterized 10 structurally unique materials of the Cu(I)/X/alpha,omega-bis(benzotriazole)alkane organic-inorganic hybrid family, {[CuCl](2)(L1)}(n) (1), {[CuBr](L2)}(n) (2), {[CuCl](2)(L3)}(n) (3), {[CuI](2)(L4)}(n) (4), {[CuBr](2)(L4)}(n) (5), {[CuBr](3)(L5)}(n) (6), {[CuCN](2)(L1)}(n) (7), {[CuCl](4)(L2)}(n) (8), {[CuBr](4)(L2)}(n) (9), and {[CuCl](2)(L4)}(n) (10), by means of elemental analyses, X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and photoluminescence measurements. Single-crystal X-ray analyses showed that the inorganic subunits in these compounds were {Cu(2)X(2)} binuclear clusters (1 and 2), {Cu(4)X(4)} cubane clusters (4, 5, and 10), {CuX}(n) single chains (3 and 7), a {Cu(3)X(3)}(n) ladderlike chain (6), and unprecedented {Cu(8)X(8)}(n) ribbons (8 and 9). The increasing dimensionality from 1-D (1-4) to 2-D (5 and 6) to 3-D (7-10) indicates that the spacer length and isomerism of the bis(benzotriazole)alkane ligands play an essential role in the formation of the framework of the Cu(I) hybrid materials. The influence of counteranions and pi-pi stacking interactions on the formation and dimensionality of these hybrid coordination polymers has also been explored. In addition, all the complexes exhibit high thermal stability and strong fluorescence properties in the solid state at ambient temperature.

  10. Enthalpy of mixing of liquid Cu-Fe-Hf alloys at 1873 K

    Energy Technology Data Exchange (ETDEWEB)

    Agraval, Pavel; Turchanin, Mikhail [Donbass State Engineering Academy, Kramatorsk (Ukraine). Metallurgical Dept.; Dreval, Liya [Donbass State Engineering Academy, Kramatorsk (Ukraine). Metallurgical Dept.; Materials Science International Services GmbH (MSI), Stuttgart (Germany)

    2016-12-15

    In the ternary Cu-Fe-Hf system, the mixing enthalpies of liquid alloys were investigated at 1873 K using a high-temperature isoperibolic calorimeter. The experiments were performed along the sections x{sub Cu}/x{sub Fe} = 3/1, 1/1 at x{sub Hf} = 0-0.47 and along the section x{sub Cu}/x{sub Fe} = 1/3 at x{sub Hf} = 0-0.13. The limiting partial enthalpies of mixing of undercooled liquid hafnium in liquid Cu-Fe alloys, Δ{sub mix} anti H{sub Hf}{sup ∞}, are (-122 ± 9) kJ mol{sup -1} (section x{sub Cu}/x{sub Fe} = 3/1), (-106 ± 9) kJ mol{sup -1} (section x{sub Cu}/x{sub Fe} = 1/1), and (-105 ± 2) kJ mol{sup -1} (section x{sub Cu}/x{sub Fe} = 1/3). In the investigated composition range, the integral mixing enthalpies are sign-changing. For the integral mixing enthalpy, an analytical expression was obtained by the least squares fit of the experimental results using the Redlich-Kister-Muggianu polynomial.

  11. Hydrothermal synthesis of Cu-Fe3O4 nanocomposites towards catalytic degradation of organic dyes

    Science.gov (United States)

    Han, Jishu; Sun, Xiaoxia; Zhao, Ruiyang; Gao, Hongtao; Wang, Lei

    2017-07-01

    Degradation of hazardous organic dyes utilizing multifunctional catalytic materials is supposed to be an efficient and promising method. Here, homogeneous Cu-Fe3O4 nanocomposites are synthesized through a facile and versatile one-pot hydrothermal method. The prepared Cu-Fe3O4 possesses spherical structure with rough surface and average diameter of 230 nm. High catalytic activity and structure stability make Cu-Fe3O4 nanocomposites effectively degrade rhodamine B, methylene blue, methyl orange, and congo red. The existence of magnetic Fe3O4 leads the nanocomposites to separate from the solution through external magnet and reuse for cycle degradation. And during the cyclic utilization, Cu-Fe3O4 nanocomposites keep high catalytic activity and, thus, could be used as an efficient degradation catalyst for the application of organic dyes.

  12. Nitrate removal by Fe0/Pd/Cu nano-composite in groundwater.

    Science.gov (United States)

    Liu, Hongyuan; Guo, Min; Zhang, Yan

    2014-01-01

    Nitrate pollution in groundwater shows a great threat to the safety of drinking water. Chemical reduction by zero-valent iron is being considered as a promising technique for nitrate removal from contaminated groundwater. In this paper, Fe0/Pd/Cu nano-composites were prepared by the liquid-phase reduction method, and batch experiments of nitrate reduction by the prepared Fe0/Pd/Cu nano-composites under various operating conditions were carried out. It has been found that nano-Fe0/Pd/Cu composites processed dual functions: catalytic reduction and chemical reduction. The introduction of Pd and Cu not only improved nitrate removal rate, but also reduced the generation of ammonia. Nitrate removal rate was affected by the amount of Fe0/Pd/Cu, initial nitrate concentration, solution pH, dissolved oxygen (DO), reaction temperature, the presence of anions, and organic pollutant. Moreover, nitrate reduction by Fe0/Pd/Cu composites followed the pseudo-first-order reaction kinetics. The removal rate of nitrate and total nitrogen were about 85% and 40.8%, respectively, under the reaction condition of Fe-6.0%Pd-3.0%Cu amount of 0.25 g/L, pH value of 7.1, DO of 0.42 mg/L, and initial nitrate concentration of 100 mg/L. Compared with the previous studies with Fe0 alone or Fe-Cu, nano-Fe-6%Pd-3%Cu composites showed a better selectivity to N2.

  13. Efficient degradation of carbamazepine by easily recyclable microscaled CuFeO{sub 2} mediated heterogeneous activation of peroxymonosulfate

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Yaobin, E-mail: yaobinding@mail.scuec.edu.cn [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, College of Resources and Environmental Science, South-Central University for Nationalities, Wuhan 430074 (China); Tang, Hebin [College of Pharmacy, South-Central University for Nationalities, Wuhan 430074 (China); Zhang, Shenghua; Wang, Songbo [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, College of Resources and Environmental Science, South-Central University for Nationalities, Wuhan 430074 (China); Tang, Heqing, E-mail: tangheqing@mail.scuec.edu.cn [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, College of Resources and Environmental Science, South-Central University for Nationalities, Wuhan 430074 (China)

    2016-11-05

    Highlights: • CuFeO{sub 2} microparticles were prepared by a microwave-assisted hydrothermal method. • CuFeO{sub 2} microparticles efficiently catalyzed the activation of peroxymonosulfate. • Quenching experiments confirmed sulfate radicals as the major reactive radicals. • Carbamazepine was rapidly degraded by micro-CuFeO{sub 2}/peroxymonosulfate. • Feasibility of CuFeO{sub 2}/peroxymonosulfate was tested for treatment of actual water. - Abstract: Microscaled CuFeO{sub 2} particles (micro-CuFeO{sub 2}) were rapidly prepared via a microwave-assisted hydrothermal method and characterized by scanning electron microscopy, X-ray powder diffraction and X-ray photoelectron spectroscopy. It was found that the micro-CuFeO{sub 2} was of pure phase and a rhombohedral structure with size in the range of 2.8 ± 0.6 μm. The micro-CuFeO{sub 2} efficiently catalyzed the activation of peroxymonosulfate (PMS) to generate sulfate radicals (SO{sub 4}·−), causing the fast degradation of carbamazepine (CBZ). The catalytic activity of micro-CuFeO{sub 2} was observed to be 6.9 and 25.3 times that of micro-Cu{sub 2}O and micro-Fe{sub 2}O{sub 3}, respectively. The enhanced activity of micro-CuFeO{sub 2} for the activation of PMS was confirmed to be attributed to synergistic effect of surface bonded Cu(I) and Fe(III). Sulfate radical was the primary radical species responsible for the CBZ degradation. As a microscaled catalyst, micro-CuFeO{sub 2} can be easily recovered by gravity settlement and exhibited improved catalytic stability compared with micro-Cu{sub 2}O during five successive degradation cycles. Oxidative degradation of CBZ by the couple of PMS/CuFeO{sub 2} was effective in the studied actual aqueous environmental systems.

  14. Facile preparation of magnetic mesoporous Fe3O4/C/Cu composites as high performance Fenton-like catalysts

    Science.gov (United States)

    Li, Keyan; Zhao, Yongqin; Janik, Michael J.; Song, Chunshan; Guo, Xinwen

    2017-02-01

    Fe-Cu composites with different compositions and morphologies were synthesized by a hydrothermal method combined with precursor thermal transformation. γ-Fe2O3/CuO and α-Fe2O3/CuO were obtained by calcining the Fe and Cu tartrates under air atmosphere at 350 °C and 500 °C, respectively, while Fe3O4/C/Cu was obtained by calcining the tartrate precursor under N2 atmosphere at 500 °C. The Fe3O4/C/Cu composite possessed mesoporous structure and large surface area up to 133 m2 g-1. The Fenton catalytic performance of Fe3O4/C/Cu composite was closely related to the Fe/Cu molar ratio, and only proper amounts of Fe and Cu exhibited a synergistic enhancement in Fenton catalytic activity. Cu inclusion reduced Fe3+ to Fe2+, which accelerated the Fe3+/Fe2+ cycles and favored H2O2 decomposition to produce more hydroxyl radicals for methylene blue (MB) oxidation. Due to the photo-reduction of Fe3+ and Cu2+, the Fenton catalytic performance was greatly improved when amending with visible light irradiation in the Fe3O4/C/Cu-H2O2 system, and MB (100 mg L-1) was nearly removed within 60 min. The Fe3O4/C/Cu composite showed good recyclability and could be conveniently separated by an applied magnetic field. Compared with conventional methods for mesoporous composite construction, the thermolysis method using mixed metal tartrates as precursors has the advantages of easy preparation and low cost. This strategy provides a facile, cheap and green method for the synthesis of mesoporous composites as excellent Fenton-like catalysts, without any additional reductants or organic surfactants.

  15. Molecular dynamics simulations of concentration-dependent defect production in Fe-Cr and Fe-Cu alloys

    Science.gov (United States)

    Zhang, Yaxuan; Schwen, Daniel; Bai, Xian-Ming

    2017-12-01

    Molecular dynamics simulations are conducted to study the effects of alloying elements on the primary damage behaviors in three Fe-based ferritic alloy systems: (1) a Fe-Cr system in which the heat of mixing changes its sign with the Cr concentration; (2) a Fe-Cu system that has a positive heat of mixing; and (3) an ideal but artificial Fe-Cr system that has a zero heat of mixing, which is used as a reference system to investigate solute interstitial formation based on probability. It is found that in these alloys, the solute type and concentration do not have a significant effect on the total number of surviving Frenkel pairs. However, the fraction of solute interstitials has distinct behaviors. In Fe-Cr, the Cr interstitial fraction is much higher than the Cr solute concentration and the Cr interstitial production efficiency decreases with the increasing Cr concentration. By contrast, in Fe-Cu, Cu interstitials are barely produced. In the ideal alloy, the solute interstitial fraction is close to the solute concentration. The defect formation energies in both dilute and concentrated alloys, interstitial binding energies, liquid diffusivities of Fe and solute atoms, and heat of mixing have been calculated for both Fe-Cr and Fe-Cu alloys. Among them, we find that the relative thermodynamic stability between Fe self-interstitials and solute interstitials plays the most important role in the solute interstitial production behaviors. The decrease of Cr interstitial production efficiency with increasing Cr concentration can be explained by the probability distribution functions of solute interstitial formation energy in concentrated alloys.

  16. Solute redistribution during phase separation of ternary Fe-Cu-Si alloy

    Science.gov (United States)

    Luo, S. B.; Wang, W. L.; Xia, Z. C.; Wu, Y. H.; Wei, B.

    2015-06-01

    Ternary Fe48Cu48Si4 immiscible alloy was rapidly solidified under the containerless microgravity condition inside a drop tube. Liquid phase separation took place in the alloy melt and led to the formation of various segregated structures. The core-shell structure consisting of Fe-rich and Cu-rich zones and the homogenously dispersed structure were the major structural morphologies. Phase field simulation results revealed that the two-layer core-shell was the final structure of liquid phase separation. The solute redistribution of liquid Fe48Cu48Si4 alloy experienced the macroscopic solute distribution induced by liquid phase separation, the secondary phase separation within the separated liquid phases and the solute trapping during rapid solidification. Energy dispersive spectroscopy analysis showed that the solute Si was enriched in the Fe-rich zone whereas depleted in the Cu-rich zone. In addition, both αFe and (Cu) phases in the Fe-rich zone exhibited a conspicuous solute trapping effect. As compared with (Cu) phase, αFe phase had a stronger affinity with solute Si.

  17. Structural and magnetic studies of the alloy system CuAl 1- xFe x

    Science.gov (United States)

    Saleh, A. S.; Al-Jaber, R.; Malkawi, A.; Mahmood, S.; Abu-Aljarayesh, I.

    1991-09-01

    We report structural and magnetic measurements on the alloy system CuAl 1- xFe x for x = 0.1, 0.2, 0.3 and 0.4. The results have shown that the system is a multiphase one for all values of x. At x≤0.2, a dominant CuAl phase with a B2 structure and a significantly weaker B2-FeAl phase exist. As x increases ( x>0.2) the FeAl phase grows stronger and the CuAl phase disappears, giving rise to the cubic γ 2-Cu 9Al 4 phase, and then to the orthorhombic β '1-Cu 3Al phase for x≥0.4. The development of the magnetic properties as x increases seems to be consistent with the above structural changes. At low values of x a dominant diamagnetic response was observed and was associated with the CuAl phase. As x increases ( x>0.2) the paramagnetic signal of the FeAl phase dominates, and becomes superparamagnetic for x≥0.4, indicating an Fe-rich FeAl phase. In addition, a weak ferromagnetic component was observed for x≤0.2, and was associated with traces of Fe-rich clusters.

  18. Characterization of transparent superconductivity Fe-doped CuCrO{sub 2} delafossite oxide

    Energy Technology Data Exchange (ETDEWEB)

    Taddee, Chutirat [Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Kamwanna, Teerasak, E-mail: teekam@kku.ac.th [Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Nanotec-KKU Center of Excellence on Advanced Nanomaterials for Energy Production and Storage, Khon Kaen 40002 (Thailand); Integrated Nanotechnology Research Center (INRC), Khon Kaen University, Khon Kaen 40002 (Thailand); Amornkitbamrung, Vittaya [Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Nanotec-KKU Center of Excellence on Advanced Nanomaterials for Energy Production and Storage, Khon Kaen 40002 (Thailand); Integrated Nanotechnology Research Center (INRC), Khon Kaen University, Khon Kaen 40002 (Thailand)

    2016-09-01

    Graphical abstract: - Highlights: • Effect of Fe substitution on the physical properties in CuCrO{sub 2} is studied. • The substitution of Cr{sup 3+} by Fe{sup 3+} produces a mixed effect on the magnetic properties. • CuCr{sub 1−x}Fe{sub x}O{sub 2} delafossite oxides show transparent superconductivity. - Abstract: Delafossite CuCr{sub 1−x}Fe{sub x}O{sub 2} (0.0 ≤ x ≤ 0.15) semiconductors were synthesized using a self-combustion urea nitrate process. The effects of Fe concentration on its microstructural, optical, magnetic, and electrical properties were investigated. X-ray diffraction (XRD) analysis results revealed the delafossite structure in all the samples. The lattice spacing of CuCr{sub 1−x}Fe{sub x}O{sub 2} slightly increased with increasing substitution of Fe at the Cr sites. The optical properties measured at room temperature using UV–visible spectroscopy showed a weak absorbability in the visible light and near IR regions. The corresponding direct optical band gap was about 3.61 eV, exhibiting transparency in the visible region. The magnetic hysteresis loop measurements showed that the Fe-doped CuCrO{sub 2} samples exhibited ferromagnetic behavior at room temperature. This indicated that the substitution of Fe{sup 3+} for Cr{sup 3+} produced a mixed effect on the magnetic properties of CuCrO{sub 2} delafossite oxide. The temperature dependent resistivity measurements clearly revealed the presence of superconductivity in the CuCr{sub 1−x}Fe{sub x}O{sub 2} with a superconducting transition up to 118 K.

  19. Composition of α−Fe nanoparticles precipitated from CuFe alloy studied by hyperfine interactions

    Energy Technology Data Exchange (ETDEWEB)

    Kubániová, Denisa, E-mail: kubaniova@mbox.troja.mff.cuni.cz [Charles University, Faculty of Mathematics and Physics (Czech Republic); Cesnek, Martin, E-mail: martin.cesnek@fjfi.cvut.cz [Czech Technical University, Department of Nuclear Reactors (Czech Republic); Milkovi c, Ondrej [Slovak Academy of Sciences, Institute of Materials Research (Slovakia); Kohout, Jaroslav [Charles University, Faculty of Mathematics and Physics (Czech Republic); Miglierini, Marcel [Czech Technical University, Department of Nuclear Reactors (Czech Republic)

    2016-12-15

    Iron-based nanoparticles prepared by precipitation from solid solution of saturated binary Cu-Fe alloy were studied by transmission electron microscopy, high-energy X-ray diffraction and Mössbauer spectroscopy. The results showed that the investigated as-prepared nanoparticles contained two phases. The major phase was determined as α−Fe and the minor phase as γ−Fe{sub 2}O{sub 3}. Furthermore, additionally annealed samples in Ar protective atmosphere were investigated. Results showed clear decrease in contribution of α−Fe phase and also revealed the presence of various iron oxides (maghemite, magnetite, hematite and wűstite).

  20. Raman scattering study of delafossite magnetoelectric multiferroic compounds: CuFeO2 and CuCrO2

    Science.gov (United States)

    Aktas, O.; Truong, K. D.; Otani, T.; Balakrishnan, G.; Clouter, M. J.; Kimura, T.; Quirion, G.

    2012-01-01

    Ultrasonic velocity measurements on the magnetoelectric multiferroic compound CuFeO2 reveal that the antiferromagnetic transition observed at TN1 = 14 K might be induced by an R\\bar {3}m\\rightharpoonup C 2/m pseudoproper ferroelastic transition [1]. In that case, the group theory states that the order parameter associated with the structural transition must belong to a two-dimensional irreducible representation Eg (x2 - y2, xy). Since this type of transition can be driven by a Raman Eg mode, we performed Raman scattering measurements on CuFeO2 between 5 and 290 K. Considering that the isostructural multiferroic compound CuCrO2 might show similar structural deformations at the antiferromagnetic transition TN1 = 24.3 K, Raman measurements have also been performed for comparison. At ambient temperature, the Raman modes in CuFeO2 are observed at ωEg = 352 cm-1 and ωA1g = 692 cm-1, while these modes are detected at ωEg = 457 cm-1 and ωA1g = 709 cm-1 in CuCrO2. The analysis of the temperature dependence of the modes in both compounds shows that the frequencies of all modes increase with decreasing temperature. This typical behavior is attributed to anharmonic phonon-phonon interactions. These results clearly indicate that none of the Raman active modes observed in CuFeO2 and CuCrO2 drive the pseudoproper ferroelastic transitions observed at the Néel temperature TN1. Finally, a broad band at about 550 cm-1 observed in the magnetoelectric phase of CuCrO2 below TN2 could be associated with magnons.

  1. Raman scattering study of delafossite magnetoelectric multiferroic compounds: CuFeO2 and CuCrO2.

    Science.gov (United States)

    Aktas, O; Truong, K D; Otani, T; Balakrishnan, G; Clouter, M J; Kimura, T; Quirion, G

    2012-01-25

    Ultrasonic velocity measurements on the magnetoelectric multiferroic compound CuFeO(2) reveal that the antiferromagnetic transition observed at T(N1) = 14 K might be induced by an R3m --> pseudoproper ferroelastic transition. In that case, the group theory states that the order parameter associated with the structural transition must belong to a two-dimensional irreducible representation E(g) (x(2) - y(2), xy). Since this type of transition can be driven by a Raman E(g) mode, we performed Raman scattering measurements on CuFeO(2) between 5 and 290 K. Considering that the isostructural multiferroic compound CuCrO(2) might show similar structural deformations at the antiferromagnetic transition T(N1) = 24.3 K, Raman measurements have also been performed for comparison. At ambient temperature, the Raman modes in CuFeO(2) are observed at ω(E(g)) = 352 cm(-1) and ω(A(1g)) = 692 cm(-1), while these modes are detected at ω(E(g)) = 457 cm(-1) and ω(A(1g)) = 709 cm(-1) in CuCrO(2). The analysis of the temperature dependence of the modes in both compounds shows that the frequencies of all modes increase with decreasing temperature. This typical behavior is attributed to anharmonic phonon-phonon interactions. These results clearly indicate that none of the Raman active modes observed in CuFeO(2) and CuCrO(2) drive the pseudoproper ferroelastic transitions observed at the Néel temperature T(N1). Finally, a broad band at about 550 cm(-1) observed in the magnetoelectric phase of CuCrO(2) below T(N2) could be associated with magnons.

  2. Pressure-restored superconductivity in Cu-substituted FeSe

    Science.gov (United States)

    Schoop, Leslie M.; Medvedev, Sergey A.; Ksenofontov, Vadim; Williams, Anthony; Palasyuk, Taras; Troyan, Iwan A.; Schmitt, Jennifer; Casper, Frederick; Wang, Changhai; Eremets, Mikhail; Cava, R. J.; Felser, Claudia

    2011-11-01

    Copper doping of FeSe destroys its superconductivity at ambient pressure, even at low doping levels. Here we report the pressure-dependent transport and structural properties of Fe1.01-xCuxSe with 3% and 4% Cu doping and find that the superconductivity is restored. Metallic resistivity behavior, absent in Cu-doped FeSe, is also restored. At the low pressure of 1.5 GPa, superconductivity is seen at 6 K for 4% Cu doping, somewhat lower than the 8 K Tc of undoped FeSe. Tc reaches its maximum of 31.3 K at 7.8 GPa, lower than the maximum superconducting temperature in the undoped material under pressure (Tc max of 37 K) but still very high. X-ray diffraction shows that applied pressure decreases the lattice parameter in the basal plane, counteracting the structural effect of Cu doping, providing a possible explanation for the restoration of the superconductivity.

  3. Hydroxylation of benzene to phenol over magnetic recyclable nanostructured CuFe mixed-oxide catalyst

    CSIR Research Space (South Africa)

    Makgwane, PR

    2015-03-01

    Full Text Available A highly active and magnetically recyclable nanostructured copper–iron oxide (CuFe) catalyst has been synthesized for hydroxylation of benzene to phenol under mild reaction conditions. The obtained catalytic results were correlated with the catalyst...

  4. Effects of interfacial transition layers on the electrical properties of individual Fe 30 Co 61 Cu 9 /Cu multilayer nanowires

    KAUST Repository

    Ma, Hongbin

    2016-01-01

    In this work, we accurately measure the electrical properties of individual Fe30Co61Cu9/Cu multilayered nanowires using nanomanipulators in in situ scanning electron microscopy to reveal that interfacial transition layers are influential in determining their transport behaviors. We investigate the morphology, crystal structure and chemistry of the Fe30Co61Cu9/Cu multilayered nanowires to characterize them at the nanoscale. We also compare the transport properties of these multilayered nanowires to those of individual pure Cu nanowires and to those of alloy Fe30Co61Cu9 nanowires. The multilayered nanowires with a 50 nm diameter had a remarkable resistivity of approximately 5.41 × 10-7 Ω m and a failure current density of 1.54 × 1011 A m-2. Detailed analysis of the electrical data reveals that interfacial transition layers influence the electrical properties of multilayered nanowires and are likely to have a strong impact on the life of nanodevices. This work contributes to a basic understanding of the electrical parameters of individual magnetic multilayered nanowires for their application as functional building blocks and interconnecting leads in nanodevices and nanoelectronics, and also provides a clear physical picture of a single multilayered nanowire which explains its electrical resistance and its source of giant magnetoresistance. © The Royal Society of Chemistry 2016.

  5. Crystal structure of the quaternary compounds CuFe2AlSe4 and ...

    Indian Academy of Sciences (India)

    3Laboratorio de Análisis Químico y Estructural, Departamento de Física, Facultad de Ciencias,. Universidad de Los Andes, Mérida 5101, Venezuela. MS received 29 May 2014; accepted 3 February 2015. Abstract. The crystal structure of the quaternary compounds CuFe2AlSe4 and CuFe2GaSe4, belonging to the.

  6. Leaching of rapidly quenched Al65Cu20Fe15 quasicrystalline ribbons

    Indian Academy of Sciences (India)

    22

    the surface of melt spun QC ribbons with 10 mole of NaOH and understand the evolution of various phases. 2. Experimental details. A nominal alloy composition of a stable QC Al65Cu20Fe15 has been prepared from pure elements with purities of 99.98 wt. % of Al, 99.99 wt.% of Cu and 99.98 wt.% of Fe. The 10.

  7. Structural evolutions of the mechanically alloyed Al70Cu20Fe10 ...

    Indian Academy of Sciences (India)

    Mechanical alloying of the Al70Cu20Fe10 did not result in the formation of icosahedral quasicrystalline phase (i-phase) and a long time milling resulted in the formation of -Al(Cu,Fe) solid solution phase (-phase). The i-phase was observed only for short-time milled powders after heat treatment above 600°C. The ...

  8. Microstructural and magnetic characterizations of CoFeCu electrodeposited in self-assembled mesoporous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Fortas, G., E-mail: g.fortas@gmail.com [Centre de Recherche en Technologie des Semi-conducteur pour l’Energétique, Bd. 2 Frantz Fanon, les sept merveilles B.P.140, Alger (Algeria); Université des Sciences et de la Technologie Houari Boumediene, Faculté des Physique, BP 32 El Alia 16111 Bab Ezzouar, Alger (Algeria); Haine, N. [Université des Sciences et de la Technologie Houari Boumediene, Faculté des Physique, BP 32 El Alia 16111 Bab Ezzouar, Alger (Algeria); Sam, S.; Gabouze, N. [Centre de Recherche en Technologie des Semi-conducteur pour l’Energétique, Bd. 2 Frantz Fanon, les sept merveilles B.P.140, Alger (Algeria); Saifi, A. [Université Mouloud Mammeri, laboratoire de physique et de chimie quantique, BP No. 17 RP Hasnaoua Tizi-Ouzou 15000 (Algeria); Ouir, S. [Université Said SDB, Route De Soumaa BP 270, Blida (Algeria); Menari, H. [Centre de Recherche en Technologie des Semi-conducteur pour l’Energétique, Bd. 2 Frantz Fanon, les sept merveilles B.P.140, Alger (Algeria)

    2015-03-15

    Self-assembled mesoporous silicon with quasi-regular pore arrangements has been fabricated by the electrochemical anodization process in hydrofluoric acid solution. CoFeCu was electrodeposited in this structure from a bath containing sodium acetate as a complexing agent with a pH value of 5. The effect of current density on the morphology, the structure and the magnetic properties of CoFeCu deposit was studied by SEM, EDS, DRX and VSM. It has been shown that the morphology and structure of samples were strongly influenced by the current density and etching duration. The micrographs show the vertical and branched nanowires and also a discontinuous growth of wires. Further, the growth of a thick layer from the grain boundaries of released CoFeCu wires is produced. The magnetic hysteresis loops demonstrate that the CoFeCu nanowires exhibit easy magnetic axis perpendicular to the PS channels axis when the current density varied from 3 to 10 mA/cm{sup 2}. Nevertheless, they reveal a no magnetic anisotropy of CoFeCu nanostructures deposited only in the outside of porous silicon, probably due to the vanishing the shape anisotropy. - Highlights: • CoFeCu deposit has been electrodeposited on self assembled mesoporous silicon. • SEM observation shows that CoFeCu embedded in Porous silicon channels. • Magnetic measurements show the anisotropy magnetic behavior of CoFeCu nanostructures. • The growth rate of nanowires is enhanced with an increase of current density.

  9. Structural evolutions of the mechanically alloyed Al70Cu20Fe10 ...

    Indian Academy of Sciences (India)

    istics of the mechanically alloyed Al70Cu20Fe10 powders with the milling time and the heat treatment were investigated by X-ray diffraction ... The w-Al7Cu2Fe1 phase (w-phase) was obtained only after heat treatment of the short-time milled and unmilled ... MA is basically a dry powder processing technique first developed ...

  10. Magnetic states of iron in metastable fcc Fe-Cu alloys

    Energy Technology Data Exchange (ETDEWEB)

    Orecchini, A. [INFM CRS-SOFT and Dipartimento di Fisica, Universita di Perugia, Via A. Pascoli, I-06123 Perugia (Italy); Sacchetti, F. [INFM CRS-SOFT and Dipartimento di Fisica, Universita di Perugia, Via A. Pascoli, I-06123 Perugia (Italy); Petrillo, C. [INFM CRS-SOFT and Dipartimento di Fisica, Universita di Perugia, Via A. Pascoli, I-06123 Perugia (Italy)]. E-mail: Caterina.Petrillo@pg.infn.it; Postorino, P. [INFM Coherentia and Dipartimento di Fisica, Universita di Roma La Sapienza, I-00185 Rome (Italy); Congeduti, A. [Synchrotron Soleil L' Orme des Merisiers, Saint Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex (France); Giorgetti, Ch. [Laboratoire pour l' Utilisation du Rayonnement Electromagnetique (LURE), Laboratoire CNRS-CEA-Ministere de la Jeunesse, de l' Education Nationale et de la Recherche, Batiment 209 D, Universite Paris Sud, B.P. 34, 91898 Orsay Cedex (France); Baudelet, F. [Synchrotron Soleil L' Orme des Merisiers, Saint Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex (France); Mazzone, G. [Ente per le Nuove Tecnologie, l' Energia e l' Ambiente (ENEA), Centro Ricerche Casaccia, Divisione Nuovi Materiali, Rome (Italy)

    2006-11-09

    X-ray magnetic circular dicroism at the K absorption edge of iron is exploited to elucidate the local spin structure of Fe in metastable, ferromagnetic fcc Fe-Cu alloys. At Fe concentrations as high as 50 at.%, Fe-Cu alloys are particularly suitable for studying the magnetic state of iron in an fcc environment, because of the negligible contribution of copper to the alloy magnetic moment. The experimental spectra are consistent with the picture of iron atoms coexisting in two different magnetic moment states and point out at the negative sign associated with the low magnetic moment state. This result brings in more evidence on multiple magnetic states, simultaneously present in 3d alloys with competing ferromagnetic and antiferromagnetic interactions, and offers a common explanation to the Invar effects recently reported for the Fe-Cu system.

  11. Catalytic ozonation of petroleum refinery wastewater utilizing Mn-Fe-Cu/Al2O 3 catalyst.

    Science.gov (United States)

    Chen, Chunmao; Yoza, Brandon A; Wang, Yandan; Wang, Ping; Li, Qing X; Guo, Shaohui; Yan, Guangxu

    2015-04-01

    There is of great interest to develop an economic and high-efficient catalytic ozonation system (COS) for the treatment of biologically refractory wastewaters. Applications of COS require options of commercially feasible catalysts. Experiments in the present study were designed to prepare and investigate a novel manganese-iron-copper oxide-supported alumina-assisted COS (Mn-Fe-Cu/Al2O3-COS) for the pretreatment of petroleum refinery wastewater. The highly dispersed composite metal oxides on the catalyst surface greatly promoted the performance of catalytic ozonation. Hydroxyl radical mediated oxidation is a dominant reaction in Mn-Fe-Cu/Al2O3-COS. Mn-Fe-Cu/Al2O3-COS enhanced COD removal by 32.7% compared with a single ozonation system and by 8-16% compared with Mn-Fe/Al2O3-COS, Mn-Cu/Al2O3-COS, and Fe-Cu/Al2O3-COS. The O/C and H/C ratios of oxygen-containing polar compounds significantly increased after catalytic ozonation, and the biodegradability of petroleum refinery wastewater was significantly improved. This study illustrates potential applications of Mn-Fe-Cu/Al2O3-COS for pretreatment of biologically refractory wastewaters.

  12. CuFeO2 formation using fused deposition modeling 3D printing and sintering technique

    Science.gov (United States)

    Salea, A.; Dasaesamoh, A.; Prathumwan, R.; Kongkaew, T.; Subannajui, K.

    2017-09-01

    CuFeO2 is a metal oxide mineral material which is called delafossite. It can potentially be used as a chemical catalyst, and gas sensing material. There are methods to fabricate CuFeO2 such as chemical synthesis, sintering, sputtering, and chemical vapor deposition. In our work, CuFeO2 is prepared by Fused Deposition Modeling (FDM) 3D printing. The composite filament which composed of Cu and Fe elements is printed in three dimensions, and then sintered and annealed at high temperature to obtain CuFeO2. Suitable polymer blend and maximum percent volume of metal powder are studied. When percent volume of metal powder is increased, melt flow rate of polymer blend is also increased. The most suitable printing condition is reported and the properties of CuFeO2 are observed by Scanning Electron Microscopy, and Dynamic Scanning Calorimeter, X-ray diffraction. As a new method to produce semiconductor, this technique has a potential to allow any scientist or students to design and print a catalyst or sensing material by the most conventional 3D printing machine which is commonly used around the world.

  13. Valence-band spectra and electronic structure of CuFeO2

    Science.gov (United States)

    Galakhov, V. R.; Poteryaev, A. I.; Kurmaev, E. Z.; Anisimov, V. I.; Bartkowski, St.; Neumann, M.; Lu, Z. W.; Klein, B. M.; Zhao, Tong-Rong

    1997-08-01

    The delafossite-type CuFeO2 single crystal was studied by means of x-ray emission and x-ray photoelectron spectroscopy. The valence state of Cu ions was found to be 1+, whereas Fe ions were found to be trivalent in the high-spin S=5/2 state. The x-ray emission (Cu Lα, Fe Lα, and O Kα) and photoelectron spectra were compared to the results of the local spin density approximation (LSDA) (full-potential linearized augmented plane wave method and linearized muffin-tin orbitals in atomic sphere approximation method) and LSDA+U calculations. It is found that the maximum of the Cu 3d state distribution is localized closer to the Fermi level than that of the Fe 3d states. The LSDA calculations contradict the experimental results and do not give a correct description of the Cu and Fe 3d positions relative to the Fermi level, and incorrectly predict metallic behaviors (semiconductor observed) and give qualitatively incorrect magnetic properties of CuFeO2. The LSDA+U calculations give a much better agreement with the observed valence-band structure, the measured electrical, and the magnetic properties.

  14. Evaluation of Concentrations and Human Health Risk of Cu, Zn, Fe ...

    African Journals Online (AJOL)

    ADOWIE PERE

    2011-12-06

    Dec 6, 2011 ... ABSTRACT: This study has investigated the concentrations of Cu, Zn and Fe in P. aurita and. T. fuscatus obtained from Bayelsa State, Nigeria and assessed the health risks associated with the consumption of these shellfishes. The concentrations of the metals in mg/kg dry wt basis mean + SD were Cu ...

  15. Strength and electrical conductivity of deformation-processed Cu-15 vol pct Fe alloys produced by powder metallurgy techniques

    Energy Technology Data Exchange (ETDEWEB)

    Jerman, G.A. (NASA, Marshall Space Flight Center, AL (United States)); Anderson, I.E.; Verhoeven, J.D. (Iowa State Univ., Ames (United States))

    1993-01-01

    Powder metallurgical techniques have been employed to prepare the precursor billets in the preparation of Cu-15 vol pct Fe alloys by deformation processing. It has been demonstrated that by (1) using high-purity gas-atomized Cu powders blended with commercial high-purity Fe powders and (2) controlling the time/temperature processing conditions within specific limits, it is possible to produce Cu-Fe deformation-processed alloys with strength/conductivity properties matching those of Cu-Nb, Cu-Ta, and Cu-Cr alloys. These properties are significantly superior to the best commercial alloys.

  16. Apparently enhanced magnetization of Cu(I)-modified γ-Fe2O3 based nanoparticles

    Science.gov (United States)

    Qiu, Xiaoyan; He, Zhenghong; Mao, Hong; Zhang, Ting; Lin, Yueqiang; Liu, Xiaodong; Li, Decai; Meng, Xiangshen; Li, Jian

    2017-11-01

    Using a chemically induced transition method in FeCl2 solution, γ-Fe2O3 based magnetic nanoparticles, in which γ-Fe2O3 crystallites were coated with FeCl3ṡ6H2O, were prepared. During the synthesis of the γ-Fe2O3 nanoparticles Cu(I) modification of the particles was attempted. According to the results from both magnetization measurements and structural characterization, it was judged that a magnetic silent "dead layer", which can be attributed to spin disorder in the surface of the γ-Fe2O3 crystallites due to breaking of the crystal symmetry, existed in the unmodified particles. For the Cu(I)-modified sample, the CuCl thin layer on the γ-Fe2O3 crystallites incurred the crystal symmetry to reduce the spin disorder, which "awakened" the "dead layer" on the surface of the γ-Fe2O3 crystallites, enhancing the apparent magnetization of the Cu(I)-modified nanoparticles. It was determined that the surface spin disorder of the magnetic crystallite could be related to the coating layer on the crystallite, and can be modified by altering the coating layer to enhance the effective magnetization of the magnetic nanoparticles.

  17. Anisotropic lattice dynamics and intermediate-phase magnetism in delafossite CuFeO2

    NARCIS (Netherlands)

    Klobes, B.; Herlitschke, M.; Rushchanskii, K. Z.; Wille, H. -C.; Lummen, T. T. A.; van Loosdrecht, P. H. M.; Nugroho, A. A.; Hermann, R. P.

    2015-01-01

    Hyperfine interactions and Fe-specific lattice dynamics in CuFeO2 were investigated by nuclear resonance scattering methods and compared to ab initio lattice dynamics calculations. Using nuclear forward scattering the collinear spin structure at temperatures below about 11 K could be confirmed,

  18. Growth and properties of Cu3N films and Cu3N/gamma '-Fe4N bilayers

    NARCIS (Netherlands)

    Borsa, D.M.; Grachev, S.Y.; Presura, C.N.; Boerma, D.O

    2002-01-01

    Copper nitride films were grown by molecular-beam epitaxy of copper in the presence of nitrogen from a radio-frequency atomic source on (001) gamma'-Fe4N/(001)MgO or directly on MgO substrates. The structural properties of the Cu3N films were found to be very dependent on the substrate and on the

  19. [Speciation analysis of trace elements Cu, Fe and Zn in serum by flame atomic absorption spectrophotometry].

    Science.gov (United States)

    Hu, Jun; Chang, Yao-Ming; Gao, Shuang-Bin; Hai, Chun-Xu; Li, Jin-Sheng; Xie, Xiao-Ping

    2008-03-01

    Since biological functions of the elements are generally different, depending on their chemical forms, chemical speciation analysis is really important in metallomics research. Thus, multielement analysis and chemical speciation of the elements in serum were carried out in the present work. A hyphenated technique was developed for high-throughput speciation analysis of the copper, iron and zinc in serum by molecular biology technology and flame atomic absorption spectrophotometry (AAS). Here, Cu, Fe and Zn in serum were classifyied as the forms of combination and non-combination. The serum protein was precipitated by 60% concentration of ethanol under hypothermy. The forms of combination of Cu, Fe and Zn in serum which combined with proteins were in precipitations, and the forms of non-combination of Cu, Fe and Zn in serum, which were free ions, were in supernatant. The total amount of Cu, Fe and Zn in serum and the amount of the forms of non-combination of Cu, Fe and Zn were analyzed by AAS. The amount of the forms of combination of Cu, Fe and Zn was obtained by calculation. The detection limit of Cu in serum by the method is around and 9.84 x 10(-3) microg x mL(-1). For Fe and Zn, the detection limit is about 2.76 x 10(-2) microg x mL(-1) and 1.06 x 10(-3) microg x mL(-1), respectively. The percentage recovery of trace elements Cu, Fe and Zn by the proposed procedure is in the range 95.0%-101.0%, 95.0%-102.0% and 95.0%-103.0%, respectively. The relative standard deviation (RSD) of trace elements Cu, Fe and Zn in the serum is in the range 1.88%-2.26%, 0.56%-1.59% and 0.34%-1.36%, respectively. Speciation of trace elements Cu, Fe and Zn in the serum of SD rat were analyzed by the method.

  20. Optical properties of CuFeO2 and CuFe1-xGaxO2 highly epitaxial thin films

    Science.gov (United States)

    Cabrera, A. L.; Wheatley, R. A.; Rojas, S.; Joshi, T.; Borisov, P.; Lederman, D.

    Delafossite thin films of 20 and 200 nm CuFeO2 and 52 nm CuFe1-xGaxO2 were grown by Pulsed Laser Deposition (PLD) on Al2O3 (0001) substrates. High epitaxial quality of the films was verified by the techniques of X-Ray Diffraction and Raman spectroscopy.. Optical transmission and reflection spectroscopies were performed on the films under vacuum and in CO2 controlled atmosphere, respectively. Tauc plots based on transmission data yielded direct optical band gap at 2.4 eV, 2.8eV and 3.1eV and indirect band gap at 0.9 eV and 1.3 eV for CuFe1-xGaxO2 (x =0.25) and the direct band gap at 1.9eV, 3.1eV and the indirect band gap at 1.1eV for the CuFeO2films. Supported by FONDECyT 1130372.

  1. Comparative study of water and carbon dioxide adsorption on CuFeO2 and CuFe1-xGaxO2 highly epitaxial thin films

    Science.gov (United States)

    Rojas, S.; Joshi, T.; Borisov, P.; Lederman, D.; Cabrera, A. L.

    Thermal programmed desorption (TPD) of CO2 and H2O from a 200 nm thick CuFeO2 and 52 nm thick CuFe1-xGaxO2 delafossite surfaces was performed in a Ultra-high vacuum (UHV) chamber. The thin films with epitaxial quality were grown by Pulsed Laser Deposition (PLD) on Al2O3 (0001) substrates . The adsorption / desorption of CO2 and H2O process was also monitored with X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). Our results revealed that carbon dioxide is preferentially chemisorbed by CuFe1-xGaxO2 over water and we observed the opposite behavior with regard to chemisorption of CO2 and H2O over CuFeO2. Hydroxyls and metal carbonates were formed on the surface due to the chemisorption of H2O and CO2. Arrhenius plots for CO2 and H2O desorption were done and activation energy for desorption were obtained. Supported by FONDECyT 1130372.

  2. Facile synthesis of CuFe2O4-Fe2O3 composite for high-performance supercapacitor electrode applications

    Science.gov (United States)

    Khan, Rashid; Habib, Muhammad; Gondal, Mohammed A.; Khalil, Adnan; Rehman, Zia Ur; Muhammad, Zahir; Haleem, Yasir A.; Wang, Changda; Wu, Chuan Qiang; Song, Li

    2017-10-01

    We report the synthesis of CuFe2O4-Fe2O3 composite material for efficient and highly stable supercapacitor electrode by using eco-friendly low-temperature co-precipitation method. The CuFe2O4-Fe2O3 composite demonstrated the highest specific capacitance of 638.24 F g-1 and excellent stability up to 2000 charge/discharge cycles. The achieved capacitance value is 16 times higher than that of pure CuFe2O4. The results revealed the extraordinary performance of CuFe2O4-Fe2O3 composite as supercapacitor electrode with excellent retention in comparison to CuFe2O4. The enhanced electrochemical activity of CuFe2O4-Fe2O3 composite is attributed to the synergistic effect which is responsible for redox coupling between Cu2+ and Fe3+ that has never been achieved by single component before.

  3. The Reaction Mechanism and Rate Constants in the Radiolysis of Fe2+-Cu2+ Solutions

    DEFF Research Database (Denmark)

    Bjergbakke, Erling; Sehested, Knud; Rasmussen, O. Lang

    1976-01-01

    Pulse radiolysis and gamma radiolysis have been used to study the reaction mechanism in the radiolysis of aqueous solutions of Fe2+ and Cu2+. A reaction scheme has been developed and confirmed by computation of the corresponding complete set of differential equations. The rate constants for some...... of the reactions have been determined at different pH's. $k_{{\\rm Cu}^{+}+{\\rm O}_{2}}=4.6\\times 10^{5}$ and $1.0\\times 10^{6}\\ {\\rm mol}^{-1}\\ {\\rm sec}^{-1}$, $k_{{\\rm Cu}^{+}+{\\rm Fe}^{3+}}=5.5\\times 10^{6}$ and $1.3\\times 10^{7}\\ {\\rm mol}^{-1}\\ {\\rm sec}^{-1}$, $k_{{\\rm Cu}({\\rm III)}+{\\rm Fe}^{2+}}=3.3\\times...

  4. Ab initio contribution to the study of complexes formed during dilute FeCu alloys radiation

    CERN Document Server

    Becquart, C S

    2003-01-01

    Cu plays an important role in the embrittlement of pressure vessel steels under radiation and entities containing both Cu atoms and vacancies seem to appear as a consequence of displacement cascades. The characterisation of the stability as well as the migration of small Cu-vacancy complexes is thus necessary to understand and simulate the formation of these entities. For instance, cascade ageing studied by kinetic Monte Carlo or by rate theory models requires a good characterisation of such complexes which are parameters for these methods. We have investigated, by ab initio calculations based on the density functional theory, point defects and small defects in dilute FeCu alloys. The structure of small Cu clusters and Cu-vacancy complexes has been determined, as well as their formation and binding energies. Their relative stability is discussed. Vacancy migration energies in the presence of Cu atoms have been calculated and analysed. All the results are compared to the figures obtained with empirical interat...

  5. Carbon dioxide and water adsorption on highly epitaxial Delafossite CuFeO2 thin film

    Science.gov (United States)

    Rojas, S.; Joshi, T.; Borisov, P.; Sarabia, M.; Lederman, D.; Cabrera, A. L.

    2015-03-01

    Thermal programmed desorption (TPD) of CO2 and H2O from a 200 nm thick CuFeO2 Delafossite surface was performed in a standard UHV chamber, The CuFeO2 thin film grown using Pulsed Laser Deposition (PLD) over an Al2O3 (0001) substrate with controlled O2 atmosphere resulted with highly epitaxial crystal structure. The adsorption/desorption of CO2 and H2O process was also monitored with X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). Our results revealed that carbon dioxide interacts with CuFeO2 forming Fe carbonates compounds on its surface. Hydroxides were also formed on the surface due to water presence. Using TPD data, Arrhenius plots for CO2 and water desorption were done and activation energy for desorption was obtained. Funds FONDECyT 1130372; Thanks to P. Ferrari.

  6. Magnetic and catalytic properties of inverse spinel CuFe2O4 nanoparticles

    Science.gov (United States)

    Anandan, S.; Selvamani, T.; Prasad, G. Guru; M. Asiri, A.; J. Wu, J.

    2017-06-01

    In this research, inverse spinel copper ferrite nanoparticles (CuFe2O4 NPs) were synthesized via citrate-nitrate combustion method. The crystal structure, particle size, morphology and magnetic studies were investigated using various instrumental tools to illustrate the formation of the inverse spinel structure. Mossbauer spectrometry identified Fe is located both in the tetrahedral and octahedral site in the ratio (40:60) and the observed magnetic parameters values such as saturation magnetization (Ms = 20.62 emu g-1), remnant magnetization (Mr = 11.66 emu g-1) and coercivity (Hc = 63.1 mTesla) revealed that the synthesized CuFe2O4 NPs have a typical ferromagnetic behaviour. Also tested CuFe2O4 nanoparticles as a photocatalyst for the decolourisation of methylene blue (MB) in the presence of peroxydisulphate as the oxidant.

  7. Penetration Depth and Low Field Vortex Behavior in κ-(ET)_2Cu[N(CN)_2]Br

    Science.gov (United States)

    Giannetta, R.; Carrington, A.; Schlueter, J.; Williams, J. M.

    1997-03-01

    The issue of pairing symmetry in organic superconductors is still controversial. Yip and Sauls(S.K. Yip and J.A. Sauls, Phys. Rev. Lett. 69), 2264 (1992). have suggested that the magnetic field dependence of the penetration depth (λ) in the Meissner state can provide a new test for d-wave symmetry. Motivated by this work, we have studied both the magnetic field and temperature dependence of the penetration depth in single crystal κ-(ET)_2Cu[N(CN)_2]Br. At low temperatures we find that λ ~ T^2 suggesting the presence of nodes in the energy gap. We present data for a variety of field orientations and show that the identification of a Meissner state in this material is itself problematic. This work was supported by NSF Grant # DMR-89-20538 and STCS/NSF DMR 91-20000 and by DoE contract # W-31-109-ENG-38.

  8. Mn-Substitution Effect on Thermal Conductivity of Delafossite-Type Oxide CuFeO2

    Science.gov (United States)

    Nozaki, T.; Hayashi, K.; Kajitani, T.

    2010-09-01

    We have prepared the CuFe1- x Mn x O2 solid solution to enhance the thermoelectric performance of CuFeO2 by reducing its thermal conductivity κ. With increasing x above 0.4, the crystal structure changes from delafossite left( {Roverline{3} m} right) to crednerite ( C2/ m). CuFe0.5Mn0.5O2 exhibits the lowest κ value of 2.28 W/m K at the theoretical density, being about one-quarter of that of the end members, CuFeO2 and CuMnO2. We discuss the temperature dependence of κ in terms of a classical phonon transport model, and conclude that local structural modulation due to the mixture of undistorted FeO6 octahedra and distorted MnO6 octahedra in CuFe1- x Mn x O2 leads to the significant reduction of κ.

  9. Heme-copper/dioxygen adduct formation relevant to cytochrome c oxidase: spectroscopic characterization of [(6L)FeIII-(O2(2-))-CuII]+.

    Science.gov (United States)

    Ghiladi, Reza A; Huang, Hong-wei; Moënne-Loccoz, Pierre; Stasser, Jay; Blackburn, Ninian J; Woods, Amina S; Cotter, Robert J; Incarvito, Christopher D; Rheingold, Arnold L; Karlin, Kenneth D

    2005-01-01

    In the further development and understanding of heme-copper dioxygen reactivity relevant to cytochrome c oxidase O(2)-reduction chemistry, we describe a high-spin, five-coordinate dioxygen (peroxo) adduct of an iron(II)-copper(I) complex, [((6)L)Fe(II)Cu(I)](BArF(20)) (1), where (6)L is a tetraarylporphyrinate with a tethered tris(2-pyridylmethyl)amine chelate for copper. Reaction of 1 with O(2) in MeCN affords a remarkably stable [t(1/2) (rt; MeCN) approximately 60 min] adduct, [((6)L)Fe(III)-(O(2) (2-))-Cu(II)](+) (2) [EPR silent; lambda(max)=418 (Soret), 561 nm], formulated as a peroxo complex based on manometry (1:O(2)=1:1; spectrophotometric titration, -40 degrees C, MeCN), mass spectrometry {MALDI-TOF-MS: (16)O(2), m/z 1191 ([((6)L)Fe(III)-((16)O(2) (2-))-Cu(II)](+)); (18)O(2), m/z 1195}, and resonance Raman spectroscopy (nu((O-O))=788 cm(-1); Delta(16)O(2)/(18)O(2)=44 cm(-1); Delta(16)O(2)/(16/18)O(2)=22 cm(-1)). (1)H and (2)H NMR spectroscopy (-40 degrees C, MeCN) reveals that 2 is the first heme-copper peroxo complex which is high-spin, with downfield-shifted pyrrole resonances (delta(pyrrole)=75 ppm, s, br) and upfield shifted peaks at delta= -22, -35, and -40 ppm, similar to the pattern observed for the mu-oxo complex [((6)L)Fe(III)-O-Cu(II)](BAr(F)) (3) (known S=2 system, antiferromagnetically coupled high-spin Fe(III) and Cu(II)). The corresponding magnetic moment measurement (Evans method, CD(3)CN, -40 degrees C) also confirms the S=2 spin state, with mu(B)=4.9. Structural insights were obtained from X-ray absorption spectroscopy, showing Fe-O (1.83 A) and Cu-O (1.882 A) bonds, and an Fe...Cu distance of 3.35(2) A, suggestive of a mu-1,2-peroxo ligand present in 2. The reaction of 2 with cobaltocene gives 3, differing from the observed full reduction seen with other heme-Cu peroxo complexes. Finally, thermal decomposition of 2 yields 3, with concomitant release of 0.5 mol O(2) per mol 2, as confirmed quantitatively by an alkaline pyrogallol dioxygen

  10. Effect of excess oxygen for CuFeO2.06 delafossite on thermoelectric and optical properties

    Science.gov (United States)

    Rudradawong, Chalermpol; Ruttanapun, Chesta

    2017-12-01

    This work presents the role of excess oxygen in CuFeO2.06 compounds on thermoelectric and optical properties. The CuFeO2.06 specimens were synthesized by solid state reaction method. X-ray diffraction technique has confirmed the CuFeO2 structure for the specimens. In particularly, CuFeO2.06 specimen revealed the structural extension of lattice parameter: a and c. Also, the specimen found increasing excess oxygen of approximately 3% as a resulted enhancement of mixed valence state of Cu+ and Cu2+ ions. XPS showed mixed valence state of the Cu+/Cu2+ ions, and Fe3+ and Fe2+ ions was also found in the CuFeO2.06 specimen. Mixed valence states contributed the co-existence of hole and electron carriers for conduction. Consequently, electrical conductivity of the CuFeO2.06 specimen increased up to 23 S/cm at 873 K. Also, increasing Seebeck coefficient was shown to be approximately 302 μV/K at 873 K. The CuFeO2.06 specimen was found power factor to be approximately 2.1 × 10-4 W/m•K2 at 873 K. The indirect optical gap of CuFeO2.06 (2.40 eV) was lower than that of the CuFeO2 (2.60 eV). Thus, thermoelectric and optical properties were governed by an existence of excess oxygen.

  11. Thermally induced magnetization dynamics of optically excited YIG /Cu /Ni81Fe19 trilayers

    Science.gov (United States)

    Mohamad, H. J.; Shelford, L. R.; Aziz, M.; Al-Jarah, U. A. S.; Al-Saigh, R.; Valkass, R. A. J.; Marmion, S.; Hickey, B. J.; Hicken, R. J.

    2017-10-01

    The response of Y3Fe5O12/Cu /Ni81Fe19 trilayer structures to excitation by a femtosecond laser pulse has been studied in optical pump-probe experiments and compared with the response of Y3Fe5O12 (YIG) and Ni81Fe19 reference samples. The optical pump induces a partial demagnetization of the Ni81Fe19 , a large thermal gradient within the YIG, and temperature differences across the interfaces within the sample stack. When a moderate magnetic field is applied close to normal to the sample plane, so as to quasialign the YIG magnetization with the field and cant the Ni81Fe19 magnetization from the plane, ultrafast demagnetization initiates precession of the Ni81Fe19 magnetization. The transient temperature profile within the samples has been modeled using a one-dimensional finite-element computational model of heat conduction, while the magnetization dynamics are well described by a macrospin solution of the Landau-Lifshitz-Gilbert equation. The precessional response of the Ni81Fe19 layers within the trilayers and the Ni81Fe19 reference sample are very similar for pump fluences of up to 1.5 mJ /c m2 , beyond which irreversible changes to the magnetic properties of the films are observed. These results suggest that the spin Seebeck effect is ineffective in modifying the precessional dynamics of the present YIG /Cu /Ni81Fe19 samples when subject to ultrafast optical excitation.

  12. Determination of metals (As, Cu, Fe, and Zn in two fish species from the Miankaleh wetland

    Directory of Open Access Journals (Sweden)

    Alipour Hossein

    2016-06-01

    Full Text Available The objective of this study was to determine the concentrations As, Cu, Fe, and Zn in the livers, gills, and muscles of vobla or Caspian roach, Rutilus caspicus (Yakovlev, and bighead goby, Neogobius gorlap (Iljin, from the Miankaleh wetland. The results showed that metal accumulation in the liver tissues was higher than in the gills and muscles for all metals, and Fe concentration was higher than Zn, Cu, and As in all the tissues studied. The concentrations of As, Cu, Fe, and Zn in the livers, gills, and muscles of bighead goby were higher than in vobla tissues, except for concentrations of As in the muscles. Fe, Cu, and Zn concentrations in the muscles were below the maximum permissible limit of the WHO and the FAO for both species, but the concentration of As in the muscles of both species exceeded the permissible limit proposed by the FAO; thus, human consumption should be limited. The levels of the other metals (Fe, Cu and Zn were completely safe.

  13. Magnetically Recyclable Fe3O4@His@Cu Nanocatalyst for Degradation of Azo Dyes.

    Science.gov (United States)

    Kurtan, U; Amir, Md; Baykal, A; Sözeri, H; Toprak, M S

    2016-03-01

    Fe3O4@His@Cu magnetic recyclable nanocatalyst (MRCs) was synthesized by reflux method using L-histidine as linker. The composition, structure and magnetic property of the product were characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Fourier Transform infrared spectroscopy (FT-IR) and vibrating sample magnetometry (VSM). Powder XRD, FT-IR and EDAX results confirmed that the as-synthesized products has Fe3O4 with spinel structure and Cu nanoparticles with moderate crystallinity without any other impurities. The surface of the Fe3O4@His nanocomposite was covered by tiny Cu nanoparticles. We examine the catalytic activity of Fe3O4@His@Cu MRCs for the degradation of two azo dyes, methyl orange (MO) and methylene blue (MB) as well as their mixture. The reusability of the nanocatalyst was good and sustained even after 3 cycles. Therefore this innovated Fe3O4@His@Cu MRCs has a potential to be used for purification of waste water.

  14. Fabrication and photocatalytic property of magnetic NiFe2O4/Cu2O composites

    Science.gov (United States)

    He, Zuming; Xia, Yongmei; Tang, Bin; Su, Jiangbin

    2017-09-01

    Magnetically separable NiFe2O4/Cu2O composites were successfully synthesized by a two-step method. The samples were characterized by XRD, XPS, SEM and VSM as well as their PL spectra and UV-vis adsorption spectra. The results showed that the NiFe2O4/Cu2O composites were composed of cubic-structured Cu2O and spinel-structured NiFe2O4, were able to absorb a large amount of visible light, exhibited excellent photocatalytic activity under simulated solar light irradiation and could be easily separated by an external magnetic field. The NiFe2O4/Cu2O composites exhibited higher photocatalytic performance than that of a single semiconductor. It was found that the prominently enhanced photocatalytic performance of NiFe2O4/Cu2O composites was ascribed to the effective separation of photo-generated electron-hole pairs and the effective generation of the hydroxyl radical •OH.

  15. Structural properties of delafossite multiferroic CuFeO2 powder

    Science.gov (United States)

    Dhruv, Preksha N.; Solanki, Neha P.; Jotania, Rajshree B.

    2017-05-01

    CuFeO2 powder has been synthesized using modified sol-gel auto-combustion technique with and without the presence of Rosa indica and Vinca (Catharanthus roseus) flowers petal extract. In the first set of experiment, CuFeO2 ferrite precursors were heated in a muffle furnace at 1150°C for 4 hrs. and slowly cooled to room temperature. In the second set of experiment, CuFeO2 ferrite precursors were prepared in presence of Rosa indica flowers petal extract and then sintered at 1150°C for 4 hrs. The comparative studies have been carried out to observe the effect of Rosa indica flower petals extract on structural properties of the multiferroic CuFeO2 powder. XRD analysis of sample CuFeO2 prepared without using flower petals extract; heated at 1150 °C for 4 hrs. shows mixed phases while the sample synthesized in presence of Rosa indica flower petals extract shows formation of pure phase.

  16. Spectro-photometric determinations of Mn, Fe and Cu in aluminum master alloys

    Science.gov (United States)

    Rehan; Naveed, A.; Shan, A.; Afzal, M.; Saleem, J.; Noshad, M. A.

    2016-08-01

    Highly reliable, fast and cost effective Spectro-photometric methods have been developed for the determination of Mn, Fe & Cu in aluminum master alloys, based on the development of calibration curves being prepared via laboratory standards. The calibration curves are designed so as to induce maximum sensitivity and minimum instrumental error (Mn 1mg/100ml-2mg/100ml, Fe 0.01mg/100ml-0.2mg/100ml and Cu 2mg/100ml-10mg/ 100ml). The developed Spectro-photometric methods produce accurate results while analyzing Mn, Fe and Cu in certified reference materials. Particularly, these methods are suitable for all types of Al-Mn, Al-Fe and Al-Cu master alloys (5%, 10%, 50% etc. master alloys).Moreover, the sampling practices suggested herein include a reasonable amount of analytical sample, which truly represent the whole lot of a particular master alloy. Successive dilution technique was utilized to meet the calibration curve range. Furthermore, the workout methods were also found suitable for the analysis of said elements in ordinary aluminum alloys. However, it was observed that Cush owed a considerable interference with Fe, the later one may not be accurately measured in the presence of Cu greater than 0.01 %.

  17. Preparation of delafossite CuFeO2 thin films by rf-sputtering on conventional glass substrate

    OpenAIRE

    Barnabé, Antoine; Mugnier, Emmanuelle; Presmanes, Lionel; Tailhades, Philippe

    2006-01-01

    CuFeO2 CuFeO2 is a delafossite-type compound and is a well known p-type semiconductor. The growth of delafossite CuFeO2 thin films on conventional glass substrate by radio-frequency sputtering is reported. The deposition, performed at room temperature leads to an amorphous phase with extremely low roughness and high density. The films consisted of a well crystallized delafossite CuFeO2 after heat treatment at 450 °C in inert atmosphere. The electrical conductivity of the film was 1 mS/cm. The...

  18. Fabrication and Electromagnetic Properties of Conjugated NH2-CuPc@Fe3O4

    Science.gov (United States)

    Yan, Liang; Pu, Zejun; Xu, Mingzhen; Wei, Renbo; Liu, Xiaobo

    2017-10-01

    Conjugated amino-phthalocyanine copper containing carboxyl groups/magnetite (NH2-CuPc@Fe3O4) has been fabricated from FeCl3·6H2O and NH2-CuPc via a simple solvothermal method and its electromagnetic properties investigated. Scanning electron microscopy and transmission electron microscopy revealed that the NH2-CuPc@Fe3O4 was a waxberry-like nanomaterial with NH2-CuPc molecules effectively embedded in the interior of Fe3O4 particles in the form of beads. Introduction of NH2-CuPc effectively improved the complementarity between the dielectric and magnetic losses of the system, resulting in excellent electromagnetic performance. The minimum reflection loss of the as-prepared composite reached -33.4 dB at 7.0 GHz for coating layer thickness of 4.0 mm and bandwidth below -10.0 dB (90% absorption) of up to 3.8 GHz. These results indicate that introduction of NH2-CuPc results in a composite with potential for use as an electromagnetic microwave absorption material.

  19.  Pressure-induced Fe↔Cu cationic valence exchange and its structural consequences: High-pressure studies of delafossite CuFeO2

    Science.gov (United States)

    Xu, W. M.; Rozenberg, G. Kh.; Pasternak, M. P.; Kertzer, M.; Kurnosov, A.; Dubrovinsky, L. S.; Pascarelli, S.; Munoz, M.; Vaccari, M.; Hanfland, M.; Jeanloz, R.

    2010-03-01

    The present high-pressure studies of CuFeO2 to 30 GPa using x-ray diffraction, along with F57e Mössbauer and Fe and CuK -edge x-ray absorption spectroscopy methods, reveal a sequence of intricate structural/electronic-magnetic pressure-induced transitions. The low-pressure R3¯m structure (0-18 GPa) is composed of sheets of FeS=5/23+ ions alternating with layers of O-CuS=01+-O dumbbells, the latter oriented along the c axis. This structure is characterized by an unusual positive d(c/a)/dP . At 18 GPa a structural transition takes place to a more isotropic C2/c structure with the O-CuS=01+-O axis tilted 28° from the c axis and with negative d(c/a)/dP . This transition corroborates with the onset of long-range antiferromagnetic order. Starting at ˜23GPa , with an initial volume reduction in ˜|ΔV/V0|=0.16 , the Cu-Fe bands overlap and this leads to a (CuS=01+FeS=5/23+)→(CuS=1/22+FeS=22+) interionic valence exchange in about 1/3 of the C2/c-CuFeO2 at 27 GPa. As a result: (i) the Cu2+-O becomes fourfold coordinated and is in a new crystallographic structure with space group P3¯m , and (ii) the Néel temperature increases above twofold [TN(CuS=1/22+FeS=22+)≈2.2TN(CuS=01+FeS=5/23+)] . This sequence of transitions is reversible with minimal hysteresis.

  20. The Cu{sub 2}FeTi{sub 3}S{sub 8} and Cu{sub 2}FeZr{sub 3}S{sub 8} compounds: Crystal structure and electroanalytical application

    Energy Technology Data Exchange (ETDEWEB)

    Kormosh, Zh., E-mail: kormosh@univer.lutsk.ua [Department of Analytical Chemistry and Eco-technology, Volyn National University, 13 Voli Ave, 43025 Lutsk (Ukraine); Fedorchuk, A. [Department of Inorganic and Organic Chemistry, Lviv National University of Veterinary Medicine and Biotechnologies, 50 Pekarska St., 79010 Lviv (Ukraine); Wojciechowski, K. [Department of Inorganic Chemistry, Faculty of Materials Science and Ceramics, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland); Tataryn, N. [Department of Analytical Chemistry and Eco-technology, Volyn National University, 13 Voli Ave, 43025 Lutsk (Ukraine); Parasyuk, O. [Department of Inorganic and Physical Chemistry, Volyn National University, 13 Voli Ave, 43025 Lutsk (Ukraine)

    2011-04-08

    The Cu{sub 2}FeTi{sub 3}S{sub 8} and Cu{sub 2}FeZr{sub 3}S{sub 8} compounds were produced by solid-state synthesis. The crystal structure of the quaternary phases was investigated by X-ray powder method. The compounds are described in the thiospinel structure (space group Fd3-bar m) with the unit cell parameters a = 1.00099(1) nm (Cu{sub 2}FeTi{sub 3}S{sub 8}) and a = 1.03837(2) nm (Cu{sub 2}FeZr{sub 3}S{sub 8}). The atomic parameters were calculated in the isotropic approximation (R{sub I} = 0.0496 and R{sub I} = 0.0422 for Cu{sub 2}FeTi{sub 3}S{sub 8} and Cu{sub 2}FeZr{sub 3}S{sub 8}, respectively). Iron(III)-selective electrodes were prepared using the chalcogenide compounds Cu{sub 2}FeTi{sub 3}S{sub 8} and Cu{sub 2}FeZr{sub 3}S{sub 8}. The electrode function slopes are 52.7 mV/pC for Cu{sub 2}FeTi{sub 3}S{sub 8} and 66.2 mV/pC for Cu{sub 2}FeZr{sub 3}S{sub 8}, the detection limits are 1 x 10{sup -5} M and 2 x 10{sup -5} M respectively. The prepared electrochemical sensors are not sensitive to Cd{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, Co{sup 2+}, Mg{sup 2+}, Cr{sup 3+}, and Fe{sup 2+} ions, and were tested in the potentiometric titration of Fe(III) with EDTA solution.

  1. Microstructure and Electrical Properties of Fe,Cu Substituted (Co,Mn)3O4 Thin Films

    DEFF Research Database (Denmark)

    Szymczewska, Dagmara; Molin, Sebastian; Hendriksen, Peter Vang

    2017-01-01

    In this work, thin films (~1000 nm) of a pure MnCo2O4 spinel together with its partially substituted derivatives (MnCo1.6Cu0.2Fe0.2O4, MnCo1.6Cu0.4O4, MnCo1.6Fe0.4O4) were prepared by spray pyrolysis and were evaluated for electrical conductivity. Doping by Cu increases the electrical conductivity......, whereas doping by Fe decreases the conductivity. For Cu containing samples, rapid grain growth occurs and these samples develop cracks due to a potentially too high thermal expansion coefficient mismatch to the support. Samples doped with both Cu and Fe show high electrical conductivity, normal grain...... growth and no cracks. By co-doping the Mn, Co spinel with both Cu and Fe, its properties can be tailored to reach a desired thermal expansion coefficient/electrical conductivity value....

  2. Microestructura y magnetismo en óxidos de Cu y Fe

    OpenAIRE

    Borzi, Rodolfo Alberto

    2001-01-01

    Este trabajo de Tesis propone un estudio experimental sobre las propiedades magnéticas de óxidos de Cu y Fe cuando se los somete a tratamientos que modifican su microestructura. Principalmente son mezclas de CuO y α-Fe2O3 -dos óxidos antiferromagnéticos-y de ferrita CuFe2O4, todos materiales con complejas propiedades magnéticas sobre los que se ha desarrollado una intensa actividad de investigación en los últimos años. La combinación de difracción de rayos x, microscopía electrónica de transm...

  3. Interdiffusion coefficients and atomic mobilities in fcc Cu-Fe-Mn alloys

    Directory of Open Access Journals (Sweden)

    Li J.

    2014-01-01

    Full Text Available In the present work, the interdiffusion coefficients in fcc Cu-Fe-Mn alloys were experimentally determined via a combination of solid/solid diffusion couples, electron probe microanalysis (EPMA technique and Matano-Kirkaldy method. Based on the reliable thermodynamic description of fcc phase in the Cu-Fe-Mn system available in the literature as well as the ternary diffusion coefficients measured in the present work, the atomic mobilities in fcc Cu-Fe-Mn alloys were assessed by utilizing the DICTRA (Diffusion Controlled TRAnsformation software package. The calculated interdiffusion coefficients based on the assessed atomic mobilities agree well with most of the experimental data. The comprehensive comparison between various model-predicted diffusion properties and the measured data, including the concentration penetration profiles, interdiffusion flux profile, and diffusion paths, further verify the reliability of the presently obtained atomic mobilities.

  4. Magnetic interactions in geometrically frustrated triangular lattice antiferromagnet CuFeO2

    Science.gov (United States)

    Fernandez-Baca, Jaime; Ye, Feng; Fishman, Randy; Kang, H. J.; Lynn, J. W.; Kimura, Tsuyoshi

    2008-03-01

    Geometrically frustrated magnetic systems have received considerable attention due to their extraordinary magnetic properties. The delafossite CuFeO2 is of particular interest because it exhibits multiferroic behavior with either the application of a magnetic field or introduction of nonmagnetic impurities. Our recent [1] on CuFeO2 shows that spin waves in this material can be explained by antiferromagnetic interactions up to third nearest neighbors within the hexagonal plane as well as out-of-plane coupling, indicating that the quasi-like Ising nature of this material results from the delicate balance between competing interactions. Two energy dips in the spin wave dispersion occur at the incommensurate wavevectors associated with multiferroic phase, and are dynamic precursors to the magnetoelectric behavior. In this talk we will present preliminary measurements of the field magnetic field dependence of these excitations as CuFeO2 approaches the multiferroic phase [1] Ye et al. Phys. Rev. Lett. 99, 157201 (2007)

  5. Alcohol sensing of p-type CuFeO2 delafossite oxide

    Science.gov (United States)

    Ruttanapun, Chesta; Hongaromkid, Yuttana; Thowladda, Warawoot; Wichainchai, Aree

    2013-06-01

    The sample of CuFeO2 delafossite was synthesized by solid state reaction for studying alcohol gas sensing properties. The Seebeck coefficient and electrical conductivity were measured in the high temperature ranging from 300 to 960 K. The CuFeO2 gas sensing displays high sensitive to ethyl alcohol gas in sensitivity ranging from 70 to 93 % and responding in 2 to 4 minute. The electronic characterization on the sample exhibits p-type conductor and displays electrical conductivity ranging from 3 to 13 S/cm with activation energy in 49 meV. This study suggests that CuFeO2 delafossite is a new one to be candidate in oxide material for alcohol gas sensing.

  6. Epitaxial growth of delafossite CuFeO2 thin films by pulse laser deposition

    Science.gov (United States)

    Li, S. Z.; Liu, J.; Wang, X. Z.; Yan, B. W.; Li, H.; Liu, J.–M.

    2012-07-01

    CuFeO2 (CFO) is a delafossite-type compound and is a well known p-type semiconductor. Epitaxial CuFeO2 thin films were prepared on Al2O3 (0 0 0 1) substrates by pulsed laser deposition. The deposition, performed at 500 °C and 10 Pa leads to epitaxial phase with extremely low roughness and high density. The oxygen pressure modulates the band energy properties of Cu 2p, Fe 3p and O1s. The results show that the low deposition oxygen pressure contributes to the chemistry ingredient and magnetization properties. Furthermore, spin-glass behavior is identified and weak-ferromagnetization property is found at a low temperature about ∼5 K.

  7. Epitaxial growth of delafossite CuFeO{sub 2} thin films by pulse laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Li, S.Z. [School of Physics, Huangshi Institute of Technology, Huangshi 435003 (China); Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Liu, J. [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Wang, X.Z [Department of Physics, Hubei Normal University, Huangshi 435000 (China); Yan, B.W.; Li, H. [School of Physics, Huangshi Institute of Technology, Huangshi 435003 (China); Liu, J.-M., E-mail: liujm@nju.edu.cn [Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2012-07-01

    CuFeO{sub 2} (CFO) is a delafossite-type compound and is a well known p-type semiconductor. Epitaxial CuFeO{sub 2} thin films were prepared on Al{sub 2}O{sub 3} (0 0 0 1) substrates by pulsed laser deposition. The deposition, performed at 500 Degree-Sign C and 10 Pa leads to epitaxial phase with extremely low roughness and high density. The oxygen pressure modulates the band energy properties of Cu 2p, Fe 3p and O1s. The results show that the low deposition oxygen pressure contributes to the chemistry ingredient and magnetization properties. Furthermore, spin-glass behavior is identified and weak-ferromagnetization property is found at a low temperature about {approx}5 K.

  8. Control of antiferromagnetic spin axis orientation in bilayer Fe/CuMnAs films.

    Science.gov (United States)

    Wadley, P; Edmonds, K W; Shahedkhah, M R; Campion, R P; Gallagher, B L; Železný, J; Kuneš, J; Novák, V; Jungwirth, T; Saidl, V; Němec, P; Maccherozzi, F; Dhesi, S S

    2017-09-11

    Using x-ray magnetic circular and linear dichroism techniques, we demonstrate a collinear exchange coupling between an epitaxial antiferromagnet, tetragonal CuMnAs, and an Fe surface layer. A small uncompensated Mn magnetic moment is observed which is antiparallel to the Fe magnetization. The staggered magnetization of the 5 nm thick CuMnAs layer is rotatable under small magnetic fields, due to the interlayer exchange coupling. This allows us to obtain the x-ray magnetic linear dichroism spectra for different crystalline orientations of CuMnAs in the (001) plane. This is a key parameter for enabling the understanding of domain structures in CuMnAs imaged using x-ray magnetic linear dichroism microscopy techniques.

  9. Exposure studies of core-shell Fe/Fe(3)O(4) and Cu/CuO NPs to lettuce (Lactuca sativa) plants: Are they a potential physiological and nutritional hazard?

    Science.gov (United States)

    Trujillo-Reyes, J; Majumdar, S; Botez, C E; Peralta-Videa, J R; Gardea-Torresdey, J L

    2014-02-28

    Iron and copper nanomaterials are widely used in environmental remediation and agriculture. However, their effects on physiological parameters and nutritional quality of terrestrial plants such as lettuce (Lactuca sativa) are still unknown. In this research, 18-day-old hydroponically grown lettuce seedlings were treated for 15 days with core-shell nanoscale materials (Fe/Fe(3)O(4), Cu/CuO) at 10 and 20mg/L, and FeSO(4)·7H(2)O and CuSO(4)·5H(2)O at 10mg/L. At harvest, Fe, Cu, micro and macronutrients were determined by ICP-OES. Also, we evaluated chlorophyll content, plant growth, and catalase (CAT) and ascorbate peroxidase (APX) activities. Our results showed that iron ions/NPs did not affect the physiological parameters with respect to water control. Conversely, Cu ions/NPs reduced water content, root length, and dry biomass of the lettuce plants. ICP-OES results showed that nano-Cu/CuO treatments produced significant accumulation of Cu in roots compared to the CuSO(4)·5H(2)O treatment. In roots, all Cu treatments increased CAT activity but decreased APX activity. In addition, relative to the control, nano-Cu/CuO altered the nutritional quality of lettuce, since the treated plants had significantly more Cu, Al and S but less Mn, P, Ca, and Mg. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Characterization of transparent superconductivity Fe-doped CuCrO2 delafossite oxide

    Science.gov (United States)

    Taddee, Chutirat; Kamwanna, Teerasak; Amornkitbamrung, Vittaya

    2016-09-01

    Delafossite CuCr1-xFexO2 (0.0 ≤ x ≤ 0.15) semiconductors were synthesized using a self-combustion urea nitrate process. The effects of Fe concentration on its microstructural, optical, magnetic, and electrical properties were investigated. X-ray diffraction (XRD) analysis results revealed the delafossite structure in all the samples. The lattice spacing of CuCr1-xFexO2 slightly increased with increasing substitution of Fe at the Cr sites. The optical properties measured at room temperature using UV-visible spectroscopy showed a weak absorbability in the visible light and near IR regions. The corresponding direct optical band gap was about 3.61 eV, exhibiting transparency in the visible region. The magnetic hysteresis loop measurements showed that the Fe-doped CuCrO2 samples exhibited ferromagnetic behavior at room temperature. This indicated that the substitution of Fe3+ for Cr3+ produced a mixed effect on the magnetic properties of CuCrO2 delafossite oxide. The temperature dependent resistivity measurements clearly revealed the presence of superconductivity in the CuCr1-xFexO2 with a superconducting transition up to 118 K.

  11. Neutron diffraction study of LnBaCuFeO5+#delta#, (Ln=Y,Pr)

    DEFF Research Database (Denmark)

    Ruiz-Aragón, M.J.; Amador, U.; Morán, E.

    1994-01-01

    Neutron diffraction studies of the title materials have been performed at 600K, R.T. and 8K. Copper and iron ions are randomly distributed in two equivalent MO2 planes being the symmetry P4/mmm for all the samples and temperatures. Some extra oxygen has been found in PrBaCuFeO5+δ destroying the AF...... ordering, present at R. T. in YBaCuFeO5. Besides this, at low temperature a magnetic phase transition has been found. On the other hand, both materials show a complex micro-structure as determined by electron diffraction....

  12. X-ray Magnetic Linear Dichroism of Fe-Ni Alloys on Cu(111)

    Science.gov (United States)

    2001-04-01

    3 mm thick. This crystal was polished mechanically and electrochemically. Laue X - ray diffraction was used to determine that the miscut was within 10...UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP012311 TITLE: X - ray Magnetic Linear Dichroism of Fe-Ni Alloys on Cu[1 11...2001 Materials Research Society X - ray Magnetic Linear Dichroism of Fe-Ni Alloys on Cu(11) 12 3 2 2 T.F. Johnson,’ S. Chiang,’ Y. Sato,’ D.A. Arena, S.A

  13. Oxygen formation in gamma-ray irradiation of Fe2+ -Cu2+ solutions

    DEFF Research Database (Denmark)

    Bjergbakke, Erling; Hart, E.J.

    1971-01-01

    The mechanism of O2 formation has been studied in 60 Co γ-ray-irradiated Fe(II) + Cu(II) solutions at 0.01 N HClO4 and at 0.01, 0.08, and 0.80 N H2 SO4. In the H2 SO4 system, ${\\rm G}({\\rm O}_{2})$ rises to plateau levels near 0.02 as the ${\\rm CuSO}_{4}/{\\rm FeSO}_{4}$ ratio increases. The plateau...

  14. Celdas galvánicas. Montaje y comprobación de la celda constituida por los pares Fe(III)/Fe(II)y Cu(II)/Cu.

    OpenAIRE

    Milla González, Miguel

    2013-01-01

    Se dispone de disoluciones de sulfato de cobre(II), sulfato de hierro(II) y nitrato de Fe(III), de un potenciómetro, un puente salino y electrodos de Cu y de grafito. Con las disoluciones citadas, montar una celda galvánica y medir su potencial. Son posibles todas las combinaciones tanto en el compartimento anódico como en el catódico.

  15. [Cu2R2BrLi(thf)3], R = Si(SiMe3)3–a complex containing five-coordinate silicon in a three-centre two-electron bond (thf = tetrahydrofuran)

    OpenAIRE

    Heine, Andreas; Herbst-Irmer, Regine; Stalke, Dietmar

    1993-01-01

    The title compound is obtained from the reaction of (Me3Si)3SiLi(thf)3 with CuBr in n-hexane and structurally characterised by X-ray diffraction; in [Cu2R2BrLi(thf)3], R = Si(SiMe3)3 one silyl ligand is bridging a very short Cu–Cu bond, resulting in a three-centre two-electron bond, while the second is terminally bound to copper; the other copper atom is linked to a lithium atom via a Cu Br Li bridge. peerReviewed

  16. Electrical characteristic of spin coated Fe-Porphyrin on Cu substrates

    Energy Technology Data Exchange (ETDEWEB)

    Utari, E-mail: utari@ugm.ac.id [Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Sebelas Maret, Jl. Ir. Sutami 36A Kentingan Surakarta 57126 (Indonesia); Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Bulaksumur BLS 21 Yogyakarta 55281 (Indonesia); Kusumandari,; Purnama, Budi, E-mail: bpurnama@mipa.uns.ac.id [Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Sebelas Maret, Jl. Ir. Sutami 36A Kentingan Surakarta 57126 (Indonesia); Mudasir [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Bulaksumur BLS 21 Yogyakarta 55281 (Indonesia); Abraha, Kamsul [Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Bulaksumur BLS 21 Yogyakarta 55281 (Indonesia)

    2016-06-17

    This paper describes the electrical-characteristics of Fe-Porphyrin thin films on Cu substrates. The thin layer samples used were deposited by spin coating methods on Cu-substrates at room temperature with and without induced magnetic field in the plane direction of the surface films. Fe-porphyrin was dissolved in chloroform and mixed with a magnetic stirrer for 60 min at a rotational speed of 200 rpm. The experimental results show that the mobility carrier charge of the Fe-Porphyrin layer with induced magnetic field during deposition has lower value than that without induced magnetic field case. The decrease of the mobility can be attribute to the change of the surface morphology in Fe-porphyrin films by means of increase in the nano-granular/nano-molecular size caused by the induce magnetic field.

  17. Weak ferromagnetic behavior, crystal structure, and electronic studies of novel [Cu(II)(Br)(PhCO 2)(Sp)] (Sp=(-)-sparteine) complex

    Science.gov (United States)

    Reyes-Ortega, Yasmi; Alcántara-Flores, José Luis; Hernández-Galindo, María del Carmen; Gutiérrez-Pérez, René; Ramírez-Rosales, Daniel; Bernès, Sylvain; Cabrera-Vivas, Blanca Martha; Durán-Hernández, Alejandro; Zamorano-Ulloa, Rafael

    2006-05-01

    Complex [Cu(II)(Br)(PhCO 2)(Sp)] 1 is obtained starting from copper(0), (-)-sparteine (sp) and benzoyl bromide. 1 Crystallizes in the monoclinic space group P2 1 with a=14.8857(11), b=8.9257(9), c=17.4456(14) Å, β=111.689(5)°, and Z=4. The UV-vis spectrum is characteristic of Cu(II) complexes with tetragonally distorted square pyramidal geometry. The far IR spectrum of 1 shows characteristic vibrations of Cu-Br (239 cm -1), Cu-N (437 cm -1) and Cu-O (466 cm -1) bonds. The 1H NMR broad chemical shifts of 1 integrated for a total of 31 protons and are typical of Cu(II) complexes. ESR spectra of polycrystalline 1 at 77 and 300 K show axial spectra with areas in the ratio A77/ A300=4.02, suggesting a very weak Cu-Cu ferromagnetic interaction. Complex 1-doped with Zn(II) gives hfs with hyperfine interaction constant value A∥=112.45×10 -4 cm -1. The magnetization vs temperature data in the 2-299 K range, show that cupric ion pairs interact through a small antiferromagnetic Heisenberg exchange energy— JS1· S2 with a ground singlet state S=0, separated by J=-1.3 cm -1 from the excited triplet state S=1. The sign of the very weak interchange interaction constant, J, does not agree with the ESR spectra areas ratio of 1 at 77 and 300 K, which is a more accurate quantification of the weak ferromagnetic interaction Cu-Cu through the space.

  18. Antiferromagnetism, superconductivity and quantum oscillations in the bifunctional organic conductor κ-(BETS){sub 2}FeBr{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Scheidhammer, Ludwig; Kunz, Michael; Biberacher, Werner; Kartsovnik, Mark V. [Walther-Meissner-Institut, Garching (Germany); Kushch, Natasha D. [Institute of Problems of Chemical Physics, Chernogolovka (Russian Federation)

    2014-07-01

    The layered organic metal κ-(BETS){sub 2}FeBr{sub 4} is a bifunctional material that consists of organic layers containing a metallic π electron system and inorganic layers that carry localized magnetic moments. It shows an antiferromagnetic (AFM) transition with the Neel temperature T{sub N}∼2.5 K and a superconducting (SC) transition at the critical temperature T{sub c}∼1.1 K. Shubnikov-de Haas oscillations have been studied in both the normal metallic and AFM states at different magnetic field orientations. From the angle dependence of the oscillation amplitude the exchange field can be obtained. The comparison of the oscillations in AFM and normal metallic state yields information on the Fermi surface reconstruction in the AFM state. We also present the angle dependence of the metamagnetic transition and discuss its influence on superconductivity.

  19. Anisotropic lattice dynamics and intermediate-phase magnetism in delafossite CuFeO$_{2}$

    OpenAIRE

    Klobes, B.; Herlitschke, M.; Rushchanskii, K. Z.; Wille, H.-C.; Lummen, T. T. A.; van Loosdrecht, P. H. M.; Nugroho, A. A.; Hermann, Raphael

    2015-01-01

    Hyperfine interactions and Fe-specific lattice dynamics in CuFeO$_{2}$ were investigated by nuclear resonance scattering methods and compared to ab initio lattice dynamics calculations. Using nuclear forward scattering the collinear spin structure at temperatures below about 11 K could be confirmed, whereas the nuclear forward scattering results in the intermediate temperature range between about 11 K and 14 K are incompatible withthe assumption of a sinusoidal distribution of spins parallel ...

  20. Charge compensation and magnetic properties in Sr and Cu doped La-Fe perovskites

    Directory of Open Access Journals (Sweden)

    de Julián Fernández C.

    2013-01-01

    Full Text Available Orthorhombic lanthanum orthoferrites La0.8Sr0.2Fe1-yCuyO3-w (y = 0 and 0.10 have been studied using X-rays and neutron powder diffraction (XRPD and NPD, magnetization measurements and 57Fe Mössbauer spectroscopy. Rietveld refinements on XRPD and NPD data show that they adopt an orthorhombic ABO3 perovskite symmetry with La/Sr and Fe/Cu atoms randomly distributed on crystal A and B sites, respectively. The magnetic structure at room temperature is antiferromagnetic, with the Fe/Cu magnetic moments aligned along the a axis. Magnetization curves versus temperature show that the compounds exhibit an overall antiferromagnetic and a weak ferromagnetic behaviour in the range 5-298 K. 57Fe Mössbauer spectroscopy measurements indicate that Fe3+ and Fe5+ ions coexist in both compounds, and the relative percentage of Fe5+ is almost the same at 77 and 170 K, rejecting a charge disproportion mechanism.

  1. A "naked" Fe(III)-(O₂²⁻)-Cu(II) species allows for structural and spectroscopic tuning of low-spin heme-peroxo-Cu complexes.

    Science.gov (United States)

    Garcia-Bosch, Isaac; Adam, Suzanne M; Schaefer, Andrew W; Sharma, Savita K; Peterson, Ryan L; Solomon, Edward I; Karlin, Kenneth D

    2015-01-28

    Here we describe a new approach for the generation of heme-peroxo-Cu compounds, using a "naked" complex synthon, [(F8)Fe(III)-(O2(2-))-Cu(II)(MeTHF)3](+) (MeTHF = 2-methyltetrahydrofuran; F8 = tetrakis(2,6-difluorophenyl)porphyrinate). Addition of varying ligands (L) for Cu allows the generation and spectroscopic characterization of a family of high- and low-spin Fe(III)-(O2(2-))-Cu(II)(L) complexes. These possess markedly varying Cu(II) coordination geometries, leading to tunable Fe-O, O-O, and Cu-O bond strengths. DFT calculations accompanied by vibrational data correlations give detailed structural insights.

  2. Exploring the mechanism and kinetics of Fe-Cu-Ag trimetallic particles for p-nitrophenol reduction.

    Science.gov (United States)

    Yuan, Yue; Yuan, Donghai; Zhang, Yunhong; Lai, Bo

    2017-11-01

    Preparation conditions of Fe-Cu-Ag trimetallic particles were optimized by single-factor and response surface methodology (RSM) batch experiments to obtain high-reactive Fe(0)-based materials for p-nitrophenol (PNP) removal. Under the optimal conditions (i.e., Fe(0) dosage of 34.86 g L(-1), theoretical Cu mass loading of 81.87 mg Cu/g Fe, theoretical Ag mass loading of 1.15 mg Ag/g Fe, and preparation temperature of 52.1 °C), the actual rate constant (kobs) of PNP reduction in 5 min was 1.64 min(-1), which shows a good agreement between the model prediction (1.85 min(-1)) of RSM and the experimental data. Furthermore, the high reactivity of Fe(0)-based trimetals was mainly attributed to the plating order of transition metals (i.e., Ag and Cu). Furthermore, we propose a new theory that the pyramid trimetallic structure of Fe-Cu-Ag could improve the electron transport and create active sites with high electron density at the surface (Ag layer) that could enhance the generation of surface-bonded atomic hydrogen ([H]abs) or the direct reduction of pollutant. Moreover, Fe-Cu-Ag trimetallic particles were characterized by SEM, EDS, and XPS, which also could confirm the proposed theory. In addition, the leached Cu(2+)(Fe-Cu-Ag system could be neglected completely, which suggests that Fe-Cu-Ag is reliable, safe, and environment friendly. Therefore, Fe-Cu-Ag trimetallic system would be promising for the removal of pollutants from industrial wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Removal of Cu(II) and fulvic acid by graphene oxide nanosheets decorated with Fe3O4 nanoparticles.

    Science.gov (United States)

    Li, Jie; Zhang, Shouwei; Chen, Changlun; Zhao, Guixia; Yang, Xin; Li, Jiaxing; Wang, Xiangke

    2012-09-26

    Graphene oxide/Fe(3)O(4) (GO/Fe(3)O(4)) composites were synthesized and characterized by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The removal of Cu(II) and a natural organic macromolecule (fulvic acid (FA)) by GO/Fe(3)O(4) was investigated. The mutual effects of FA/Cu(II) on Cu(II) and FA sorption onto GO/Fe(3)O(4), as well as the effect of pH, ionic strength, FA/Cu(II) concentrations, and the addition sequences of FA/Cu(II) were examined. The results indicated that Cu(II) sorption on GO/Fe(3)O(4) were strongly dependent on pH and independent of ionic strength, indicating that the sorption was mainly dominated by inner-sphere surface complexation rather than outer-sphere surface complexation or ion exchange. The presence of FA leads to a strong increase in Cu(II) sorption at low pH and a decrease at high pH, whereas the presence of Cu(II) led to an increase in FA sorption. The adsorbed FA contributes to the modification of sorbent surface properties and partial complexation of Cu(II) with FA adsorbed. Different effects of FA/Cu(II) concentrations and addition sequences on Cu(II) and FA sorption were observed, indicating the difference in sorption mechanisms. After GO/Fe(3)O(4) adsorbed FA, the sorption capacity for Cu(II) was enhanced at pH 5.3, and the sorption capacity for FA was also enhanced after Cu(II) sorption on GO/Fe(3)O(4). These results are important for estimating and optimizing the removal of metal ions and organic substances by GO/Fe(3)O(4) composites.

  4. A GREENER SYNTHESIS OF CORE (FE, CU)-SHELL (AU, PT, PD AND AG) NANOCRYSTALS USING AQUEOUS VITAMIN C

    Science.gov (United States)

    A greener method to fabricate the novel core (Fe and Cu)-shell (noble metals) metal nanocrystals using aqueous ascorbic acid (vitamin C) is described. Transition metal salts such as Cu and Fe were reduced using ascorbic acid, a benign naturally available antioxidant, and then add...

  5. Complex permeability of Fe-deficient Ni-Cu-Zn ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Z.H. [Department of Physics, Phultala M.M. College, Phultala, Khulna 9210 (Bangladesh); Mahbubur Rahman, M., E-mail: mahbub235@yahoo.com [School of Engineering and Energy, Murdoch University, Murdoch, WA 6150 (Australia); Department of Physics, Jahangirnagar University, Savar, Dhaka 1342 (Bangladesh); Sikder, S.S. [Department of Physics, Khulna University of Engineering and Technology, Khulna 9203 (Bangladesh); Hakim, M.A.; Saha, D.K. [Materials Science Division, Atomic Energy Centre, Ramna, Dhaka 1000 (Bangladesh)

    2013-01-25

    Highlights: Black-Right-Pointing-Pointer Ni-Cu-Zn ferrites were studied with increase of Fe-deficiency. Black-Right-Pointing-Pointer Permeability spectra of Fe-deficient Ni-Cu-Zn ferrites are discussed. Black-Right-Pointing-Pointer Heating and cooling cycles are used for the various studies of Ni-Cu-Zn ferrites. Black-Right-Pointing-Pointer Fe-deficiency in Ni-Cu-Zn ferrites ensures high permeability. Black-Right-Pointing-Pointer Cu works as a sintering aid to the Fe-deficient Ni-Cu-Zn ferrites. - Abstract: Fe-deficient Ni-Cu-Zn ferrites with composition Ni{sub 0.28}Cu{sub 0.10}Zn{sub 0.62}O(Fe{sub 2}O{sub 3}){sub 1-x}, where x = 0.00, 0.02, 0.04, 0.06, and 0.08 were prepared by the double sintering ceramic technique. Real part of the initial permeability {mu} Prime , Curie temperature T{sub c}, imaginary part of the initial permeability {mu} Double-Prime , relative quality factor (Q-factor) of the samples were elaborately discussed as a function of frequency and temperature with increase of Fe-deficiency during the heating and cooling cycles. The temperature dependence of the imaginary part of the complex permeability curves are very interesting to note that there is a peak value of {mu} Double-Prime at particular temperature which corresponds to the T{sub c} because at this temperature the samples might be in complete spin disorder. This reflects that at T{sub c}, a ferrimagnetically ordered state over comes K{sub B}T and becomes comparable with {mu}{sub 0}H where the loss becomes maximum. Results of heating and cooling cycles were found to be very close to each other. The small difference during heating and cooling process might arise due to the thermal hysteresis which is accumulated in this work. In our study, it was noticed that the resonant frequency and T{sub c} increases first with the increase in iron deficiency and decreases after it takes a maximum at x = 0.06.

  6. Photoluminescent mixed ligand complexes of CuX (X = Cl, Br, I) with PPh3 and a polydentate imino-pyridyl ligand - Syntheses, structural variations and catalytic property

    Science.gov (United States)

    Ghorai, Anupam; Mondal, Jahangir; Patra, Goutam K.

    2015-10-01

    Three ternary copper(I) complexes [CuI2Cl2(L1)(PPh3)4] (1), [CuI2Br2(L1) (PPh3)4] (2) and [CuI2(μ-I)2 (μ-L1) (PPh3)2]n (3) have been prepared by reactions of CuX (X = Cl, Br and I) with PPh3 and the polydentate imino-pyridyl ligand L1. These complexes have been characterized by elemental analysis, IR, UV-Vis, NMR and X-ray crystallography. From single crystal structural analysis it has been found that complexes 1 and 2 are homo-dinuclear having non-bridging halide ions whereas complex 3 is a 1-D zig-zag co-ordination polymer containing bridged iodide ions. Complexes 1, 2 and 3 are photoluminescent at room temperature in chloroform whereas ligand L1 is non-emissive. The E½ values of the CuIsbnd CuII couple of 1, 2 and 3 are 0.98 V, 0.92 V and 0.42 V respectively (vs Ag/AgCl in 1 M KCl, scan rate 100 mV s-1). All three complexes function as effective catalysts for the synthesis of 2-substituted benzoxazoles.

  7. Temperature dependent structural disintegration of delafossite CuFeO2

    Science.gov (United States)

    Shojan, P.; Kumar, Ashok; Katiyar, Ram

    2009-03-01

    Single phase delafossite p-type CuFeO2 (CFO) semiconductor was synthesized by modified solid state reaction technique. X-ray diffraction (XRD) and X-ray photo spectroscopy (XPS) studies suggest pure phase of CFO and Energy dispersive X-ray spectroscopy (EDX) also revealed that the atomic ratio Cu and Fe is 1:1. The XPS spectra showed two intense Cu 2p3/2 and 2p1/2 peaks at 932.5 eV and 952 eV and two Fe 2p3/2 and 2p1/2 peaks at 710 eV and 725 eV suggesting Cu and Fe ions are in +1 and +3 state with high spin S=5/2. The room temperature Raman spectra of CFO displayed two main strong active modes at 351 cm-1 and 692 cm-1 that matched with other delaffosite structure. Temperature dependent Raman spectra indicate that the lowest mode vanished or overdammped at ˜ 400 K where as higher modes shifted to lower frequency side with significantly decreased in intensity. We have also observed a low frequency (E2^low) mode at 79 cm-1 using 532 nm (<5MHz line width) laser line. The line width and intensity of the lowest mode indicates temperature independent behavior. Raman Spectra were carried out from 80 K to 1300 K which revealed structural disintegration in CFO over 800 K in air. The structural degradation is counter confirmed by XPS, XRD, DTA measurements. Around 800 K in air, CFO disintegrates to form CuO and CuFe2O4.

  8. Comparative investigation of CuFe2O4 nano and microstructures for structural, morphological, optical and magnetic properties

    Science.gov (United States)

    Raja, G.; Gopinath, S.; Raj, R. Azhagu; Shukla, Arun K.; Alhoshan, Mansour S.; Sivakumar, K.

    2016-09-01

    CuFe2O4 nanocrystals were synthesized by the sol-gel method (SGM) and microwave method (MM) by using sucrose as a fuel. The structural, morphological, optical and magnetic properties of the products were determined and characterized in detail by X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), photoluminescence (PL) spectroscopy and vibrating sample magnetometer (VSM). The XRD results confirmed the formation of cubic phase CuFe2O4. The formation of CuFe2O4 nano and microstructures were confirmed by HR-SEM. Photoluminescence emissions were determined by PL spectra, respectively. The relatively high saturation magnetization (78.22 emu/g) of CuFe2O4-MM shows that it is ferromagnetic and low saturation magnetization (35.98 emu/g) of CuFe2O4O-SGM confirms the super paramagnetic behavior.

  9. Cu- and Fe-hexacyanoferrate as cathode materials for Potassium ion battery: A First-principles study

    Science.gov (United States)

    Targholi, Ehsan; Mousavi-Khoshdel, S. Morteza; Rahmanifara, Mohmmadsafi; Yahya, M. Z. A.

    2017-11-01

    In this paper, the efficiency of Iron-Hexacyanoferrate (FeHCF) and Copper-Hexacyanoferrate (CuHCF) as the cathode materials for using in the energy storage application have been investigated using Density Functional Theory. The changes of their lattice parameters due to the insertion of K+ cation were explored. It was found that these changes for CuHCF are less than FeHCF. FeHCF, KFHCF, CuHCF, KCuHCF, and K2CuHCF are found to have a half-metallic nature. In contrast, K2FeHCF is found to be a diamagnetic insulator. K+ diffusion through the FeHCF and CuHCF frameworks have the energy barrier of 1.46 eV and 1.00 eV, respectively.

  10. Organic Superconductor k-(BEDT-TTF)2Cu[N(CN)2]Br - A Tunable Electronic System across the Mott Transition -

    Science.gov (United States)

    Tokumoto, M.; Kinoshita, N.; Tanaka, Y.; Kinoshita, T.; Anzai, H.

    1998-03-01

    k-(BEDT-TTF)2Cu[N(CN)2]Br, is an organic superconductor with the highest Tc of 11.6K at ambient pressure (A. M. Kini et al., Inorg. Chem. 29, 2555 (1990)). We have reported a normal isotope effect,when all the hydrogen atoms of BEDT-TTF are replaced with deuterium, in other words, Tc was depressed by as much as 0.9 K (M. Tokumoto et al., J. Phys. Soc. Jpn. 60, 1426 (1991)), in contrast to the "inverse isotope effect" commonly observed in organic superconductors (K. Oshima, et al., Synth. Metals 27, A473 (1988)) . Recently, it was reported that the deuterated k-(BEDT-TTF)2Cu[N(CN)2]Br is of an insulating nature similar to k-(BEDT-TTF)2Cu[N(CN)2]Cl when cooled rapidly(Y. Nakazawa and K. Kanoda, Phys. Rev. B 53, R8875 (1996)). Here we report on the results of reexamination of the superconducting transition of deuterated k-(BEDT-TTF)2Cu[N(CN)2]Br by SQUID measurements with special attention to the cooling speed ranging from 10K/min to less than 0.01K/min. We observed a significant effect not only on the superconducting transition temperature Tc but also on the superconducting volume fraction.

  11. Influence of size effect and electron correlation to the energy band gap of CuFeO2 and AgFeO2

    Science.gov (United States)

    Ong, Khuong; Bai, Kewu; Blaha, Peter; Wu, Ping

    2007-03-01

    We have calculated the electronic structure of delafossite type oxides CuFeO2 and AgFeO2 using the Full Potential Linearlized Augmented Plane Wave (FP-LAPW) method within Perdew-Burke-Ernzerhof Generalized-Gradient Approximation (PBE-GGA). A metallic state instead of true insulating state is obtained for CuFeO2 and AgFeO2. The insulating state is reproduced when electron correlations have been taken into account. An effective Hubbard parameter for Fe, Ueff=7.86eV, has been derived based on an ab initio constraint calculation. This value is an over estimation for the optical band gaps of CuFeO2 and most probably for AgFeO2 as well. One reasonable Ueff has been derived by comparing between computational and experimental X-Ray emission spectra. The energy band gap of CuFeO2 and AgFeO2 within the PBE-GGA+U is found as charge transfer gap. Theoretical optical band gaps δ0=1.30eV, δ1=2.06eV, and δ2=3.20eV for CuFeO2 are quite compatible with experimental data. For AgFeO2 an optical band gap δ0=1.90eV has been predicted. The size effect is considered as the origin of the increase in optical and energy band gaps of AgFeO2 in comparison with CuFeO2.

  12. Comparison study of Cu-Fe-Ti and Co-Fe-Ti oxide catalysts for selective catalytic reduction of NO with NH3 at low temperature.

    Science.gov (United States)

    Zhu, Lin; Zhong, Zhaoping; Yang, Han; Wang, Chunhua

    2016-09-15

    In this paper, a series of Cu-Fe-Ti and Co-Fe-Ti oxide catalysts were prepared by sol gel method. Cu-Fe-Ti and Co-Fe-Ti oxide catalysts showed the moderate catalytic activity for selective catalytic reduction (SCR) of NO with NH3 at low temperature. The catalysts with the molar ratio as 4:1:10 (M:Fe:Ti) were selected as the representatives for comparison of reaction properties and H2O resistance, which were denoted as Cu-Fe/TiO2 and Co-Fe/TiO2 respectively. The characterization results manifested Co-Fe/TiO2 owned more adsorption capacity of the reactants and Cu-Fe/TiO2 had better redox ability. The in situ DRIFTS experiments indicated that adsorbed NH3 species and nitrate species both exhibited reaction activity for Co-Fe/TiO2, while nitric oxide was only be reduced by adsorbed NH3 species through Eley-Rideal mechanism for Cu-Fe/TiO2 at 150°C. Co-Fe/TiO2 exhibited the better resistance to H2O and its temperature window shifted towards the higher temperature in presence of 10vol% H2O, while the SCR activity of Cu-Fe/TiO2 was inhibited significantly in the whole temperature range investigated. The suppression of adsorption and activation for NH3 and NOx might be the reasons for the reversible inactivation, which was confirmed by the inhibitation of catalytic activities for separation NH3 and NO oxidation under the wet condition. We speculated that different thermal stability of adsorbed species and redox capacity of catalysts leaded to the different SCR behavior in absence and presence of H2O. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. On the concentration and separation of the trace-elements Fe, Cu, Zn, Mn, Pb, Mo and Co : III. Paper chromatography

    NARCIS (Netherlands)

    Erkelens, P.C. van

    Paper chromatographic separations are described by which the minor constituents of biological ashes are separated either into: (Pb) --- Mn --- Co --- (Pb) --- Cu --- Fe, Mo, Zn; or into: Cu, Mn, Co --- Pb --- Fe --- Mo --- Zn.

  14. Photocatalytic performances and activities of Ag-doped CuFe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Zhengru, E-mail: zhengruzhu@gmail.com [Research Center of Hydrology and Water Source, School of Urban and Environment, Liaoning Normal University, Dalian, 116029 (China); State Key Laboratory of Fine Chemical, Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024 (China); Li, Xinyong; Zhao, Qidong [State Key Laboratory of Fine Chemical, Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024 (China); Li, Yonghua; Sun, Caizhi; Cao, Yongqiang [Research Center of Hydrology and Water Source, School of Urban and Environment, Liaoning Normal University, Dalian, 116029 (China)

    2013-08-01

    Graphical abstract: - Highlights: • CuFe{sub 2}O{sub 4} nanocrystals were synthesized by a co-precipitation method. • Ag/CuFe{sub 2}O{sub 4} catalyst was prepared by the wetness impregnation strategy. • The structural properties of Ag/CuFe{sub 2}O{sub 4} were investigated by XRD, TEM, DRS, and XPS techniques. • Ag/CuFe{sub 2}O{sub 4} has higher photocatalytic activity. - Abstract: In this work, CuFe{sub 2}O{sub 4} nanoparticles were synthesized by a chemical co-precipitation route. The Ag/CuFe{sub 2}O{sub 4} catalyst was prepared based on the CuFe{sub 2}O{sub 4} nanoparticles by the incipient wetness impregnation strategy, which showed excellent photoelectric property and catalytic activity. The structural properties of these samples were systematically investigated by X-ray powder diffraction (XRD), transmission electronic microscopy (TEM), UV–vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) techniques. The photo-induced charge separation in the samples was demonstrated by surface photovoltage (SPV) measurement. The photocatalytic degradation of 4-CP by the Ag/CuFe{sub 2}O{sub 4} and CuFe{sub 2}O{sub 4} samples were comparatively studied under xenon lamp irradiation. The results indicate that the Ag/CuFe{sub 2}O{sub 4} sample exhibited the higher efficiency for the degradation of 4-CP.

  15. Rapid synthesis of Fe-doped CuO-Ce0.8Zr0.2O2 catalysts for CO preferential oxidation in H2-rich streams: Effect of iron source and the ratio of Fe/Cu

    Science.gov (United States)

    Wang, Jing; Han, Caiyun; Gao, Xiaoya; Lu, Jichang; Wan, Gengpin; He, Dedong; Chen, Ran; Chen, Kezhen; He, Sufang; Luo, Yongming

    2017-03-01

    A facile route (urea grind combustion method) is described for the rapid synthesis of Fe-doped Cu-Ce-Zr catalysts within 30 min through simple grinding and combustion. The effects of iron source and Fe/Cu mass ratio on the performances of the catalysts for CO preferential oxidation (CO-PROX) are evaluated. The influences of H2O, CO2, and their mixture on the activity as well as stability of the catalysts are also investigated. The samples are characterized by XRD, N2 adsorption-desorption, H2-TPR, TEM, Raman and XPS. Fe(NO3)3 is found to be superior to FeCl3 and Fe2(SO4)3 as the iron source for Fe-CuCZ catalyst. Among the different synthesized catalysts, 1/10Fe(N)-CuCZ is found to be the most active catalyst, indicating that the optimal Fe/Cu mass ratio is 1/10. The influences of H2O, CO2, and H2O + CO2 on the catalytic performance of 1/10Fe(N)-CuCZ are in the order of CO2 catalytic activity and excellent stability even in the presence of H2O and CO2. The excellent catalytic performance can be attributed to the synergy between the highly dispersed copper species and ceria, as well as the formation of more oxygen vacancies and reduced copper species.

  16. Unusual Solidification Behavior of the Suction-Cast Cu-Zr-Al-Y Alloy Doped with Fe

    Science.gov (United States)

    Kozieł, Tomasz; Cios, Grzegorz; Latuch, Jerzy; Pajor, Krzysztof; Bała, Piotr

    2017-04-01

    The effect of iron addition on the microstructure of the Cu-Zr-Al-Y glass-forming alloy was studied. Despite a high superficial cooling rate, small Fe additions (1.5 and 3 pct) induced formation of crystalline CuZr and AlCu2Zr phases on the outer layers of suction-cast rods. As the melt composition near the solid/liquid interface was depleted in Fe, the remaining melt vitrified at a relatively low cooling rate.

  17. An investigation on microwave sintering of Fe, Fe–Cu and Fe–Cu–C ...

    Indian Academy of Sciences (India)

    Ferrous. PM alloys are widely used for a variety of structural applica- tions, and the predominant one is in the automotive industry. The copper steel PM parts are used ..... On examination of the micrograph of Fe–2Cu, homogeneously distributed copper clusters are observed in Fe-matrix after sintering. Because, the solubility ...

  18. Equilibrium Sorption studies of Fe, Cu and Co ions in aqueous ...

    African Journals Online (AJOL)

    Recinius Communis Linn a commonly found herbal plant was used to prepare activated carbon by physicochemical activation method. The sorption capacity of this bio-resource material to remove Fe(III), Cu(II) and Co(II) from aqueous solutions was determined by batch tests. The influences of important parameters such as ...

  19. Evaluation of Concentrations and Human Health Risk of Cu, Zn, Fe ...

    African Journals Online (AJOL)

    . fuscatus obtained from Bayelsa State, Nigeria and assessed the health risks associated with the consumption of these shellfishes. The concentrations of the metals in mg/kg dry wt basis mean + SD were Cu (57.0 + 4.0) Zn (63.8 + 9.6) and Fe ...

  20. Levels Of Mn, Fe, Ni, Cu, Zn And Cd, In Effluent From A Sewage ...

    African Journals Online (AJOL)

    This study reports the results of preliminary investigation of heavy metal levels-Ni, Cd, Fe, Zn, Cu and Mn; pH; temperature and electrical conductivity in effluents from a sewage treatment oxidation pond and its receiving stream. The heavy metal concentrations were determined with Inductively Coupled Plasma-Mass ...

  1. Assessment of heavy metals (Pb, Cu, Cr, Cd and Fe) in the ...

    African Journals Online (AJOL)

    Assessment of heavy metals (Pb, Cu, Cr, Cd and Fe) in the groundwater wells in the vicinity of Nyanza. Municipal Solid waste in Kigali City- Rwanda. H. Nsengimanaa*, B. Bigirimanab, M. Suwab, A. Mukubwab, W. Debruynb,. N. Kalisaa. aNational University of Rwanda, Faculty of Science, PO Box 117 Butare, Rwanda,.

  2. Macronutrient status and speciation of cu, fe, zn and pb in soil ...

    African Journals Online (AJOL)

    Soils at 100m away from the discharge point were regarded as normal or uncontaminated soils, while different extractants were used to determine the levels of Fe, Cu, Zn and Pb. The results showed enrichment of the soils in P, N, Ca, Mg, Na, K due to the application of the POME. Copper, Iron and Pb were predominant in ...

  3. An investigation on microwave sintering of Fe, Fe–Cu and Fe–Cu–C ...

    Indian Academy of Sciences (India)

    The powder characteristics of metallic powders play a key role during sintering. Densification and mechanical properties were also influenced by it. The current study examines the effect of heating mode on densification, microstructure, phase compositions and properties of Fe, Fe–2Cu and Fe–2Cu–0.8C systems.

  4. Ferromagnetic resonance investigation of nanocrystalline FeCuNbSiB

    Indian Academy of Sciences (India)

    An elaborate line-shape analysis of the ferromagnetic resonance (FMR) spectra taken in the temperature range 100 K to 350 K on amorphous FeCuNbSiB alloys before and after nanocrystallizing them reveals that in the nanocrystalline state,. spin wave stiffness () is enhanced while the saturation magnetization, S , is ...

  5. Quantitative trait loci controlling Cu, Ca, Zn, Mn and Fe content in ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Genetics; Volume 87; Issue 3. Quantitative trait loci controlling Cu, Ca, Zn, Mn and Fe content in rice grains. Kaiyang Lu Lanzhi Li Xingfei Zheng Zhihong Zhang Tongmin Mou Zhongli Hu. Research Note Volume 87 Issue 3 December 2008 pp 305-310 ...

  6. Determination of the levels of heavy metal (Cu, Fe, Ni, Pb and Cd ...

    African Journals Online (AJOL)

    MICHAEL HORSFALL

    ABSTRACT: The aim of this study was to use AAS to determine the levels of concentration (g/kg) of heavy metals: copper (Cu),Iron (Fe), Nickel (Ni), lead (Pb) and. Cadmuim (Cd) uptake by pumpkin (Telfairia occidentalis) leaves cultivated in Pots containing varying concentrations of contaminated soil samples labeled A to E.

  7. A critical consideration of magnetism and composition of (bcc) Cu precipitates in (bcc) Fe

    Energy Technology Data Exchange (ETDEWEB)

    Schober, M. [University of Leoben, Department of Physical Metallurgy and Materials Testing, Leoben (Austria); Montanuniversitaet Leoben, Department Metallkunde und Werkstoffpruefung, Leoben (Austria); Eidenberger, E.; Leitner, H. [University of Leoben, Department of Physical Metallurgy and Materials Testing, Leoben (Austria); Staron, P. [GKSS Research Centre, Institute of Materials Research, Geesthacht (Germany); Reith, D.; Podloucky, R. [University of Vienna, Department for Physical Chemistry, Vienna (Austria)

    2010-06-15

    Atom probe and small-angle neutron scattering (SANS) measurements were carried out in order to investigate the chemical composition of (bcc) Cu precipitates in a (bcc) Fe matrix. The ratio of nuclear and magnetic integrated intensities (R-value) found by SANS is compared to a theoretical model which is based on the chemical composition obtained from the atom probe data. Furthermore, density functional theory calculations were performed to derive the magnetic moment per atom and the lattice parameters of the Cu alloys modeled in terms of supercells. The calculated and measured R-values agree rather well suggesting that Fe atoms are incorporated in the Cu precipitates up to concentrations of about 50 at.%. (orig.)

  8. Fabrication and fibre matrix interface characteristics of Cu/C(Fe composite

    Directory of Open Access Journals (Sweden)

    Li Y.

    2009-01-01

    Full Text Available Cu/C composites were successfully fabricated by three step electro-deposition. The effects of hot pressure temperature and alloy element Fe on the interface characteristic of Cu/C composite were investigated. The results showed that the hot pressure temperature and interface characteristic have a great effect on mechanical properties of the composite. The tensile strength and hardness increase firstly and then decrease with the increasing of hot pressure temperature, and a tensile rupture appears when the hot pressure temperature is 650, 700 and 900oC. The addition of alloy element Fe not only improves the tensile strength and the lateral shear strength of the Cu/C composite, but also changes the interface bond type from the physical bond type to the chemical bond type.

  9. Photodegradation of Methyl Orange Using Magnetically Recoverable AgBr@Ag3PO4/Fe3O4 Photocatalyst under Visible Light

    Directory of Open Access Journals (Sweden)

    Zhen Wang

    2014-01-01

    Full Text Available A novel magnetically recoverable AgBr@Ag3PO4/Fe3O4 hybrid was prepared by a simple deposition-precipitation approach and characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and UV-Vis diffuse reflectance spectroscopy (DRS. The results revealed that the photocatalytic activity and stability of AgBr@Ag3PO4/Fe3O4 composite toward decomposition of methyl orange (MO dye were superior to those of pure Ag3PO4 under visible light irradiation. The photocatalytic activity enhancement of AgBr@Ag3PO4/Fe3O4 is closely related to the efficient separation of electron-hole pairs derived from the matching band potentials between Ag3PO4 and AgBr, as well as the good conductivity of Fe3O4. Moreover, the photocatalyst could be easily separated by applying an external magnetic field due to its magnetic property. The quenching effects of different scavengers proved that active h+ and played the major role for the MO degradation. This work would provide new insight for the construction of visible light responsible photocatalysts with high performance, good stability, and recoverability.

  10. 'Venus trapped, Mars transits': Cu and Fe redox chemistry, cellular topography and in situ ligand binding in terrestrial isopod hepatopancreas.

    Science.gov (United States)

    Kille, P; Morgan, A J; Powell, K; Mosselmans, J F W; Hart, D; Gunning, P; Hayes, A; Scarborough, D; McDonald, I; Charnock, J M

    2016-03-01

    Woodlice efficiently sequester copper (Cu) in 'cuprosomes' within hepatopancreatic 'S' cells. Binuclear 'B' cells in the hepatopancreas form iron (Fe) deposits; these cells apparently undergo an apocrine secretory diurnal cycle linked to nocturnal feeding. Synchrotron-based µ-focus X-ray spectroscopy undertaken on thin sections was used to characterize the ligands binding Cu and Fe in S and B cells of Oniscus asellus (Isopoda). Main findings were: (i) morphometry confirmed a diurnal B-cell apocrine cycle; (ii) X-ray fluorescence (XRF) mapping indicated that Cu was co-distributed with sulfur (mainly in S cells), and Fe was co-distributed with phosphate (mainly in B cells); (iii) XRF mapping revealed an intimate morphological relationship between the basal regions of adjacent S and B cells; (iv) molecular modelling and Fourier transform analyses indicated that Cu in the reduced Cu(+) state is mainly coordinated to thiol-rich ligands (Cu-S bond length 2.3 Å) in both cell types, while Fe in the oxidized Fe(3+) state is predominantly oxygen coordinated (estimated Fe-O bond length of approx. 2 Å), with an outer shell of Fe scatterers at approximately 3.05 Å; and (v) no significant differences occur in Cu or Fe speciation at key nodes in the apocrine cycle. Findings imply that S and B cells form integrated unit-pairs; a functional role for secretions from these cellular units in the digestion of recalcitrant dietary components is hypothesized. © 2016 The Authors.

  11. Magnetic and catalytic properties of inverse spinel CuFe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Anandan, S., E-mail: sanand@nitt.edu [Nanomaterials and Solar Energy Conversion Lab, Department of Chemistry, National Institute of Technology, Trichy 620 015 (India); Department of Environmental Engineering and Science, Feng Chia University, Taichung 407, Taiwan (China); Selvamani, T.; Prasad, G. Guru [Nanomaterials and Solar Energy Conversion Lab, Department of Chemistry, National Institute of Technology, Trichy 620 015 (India); Asiri, A.M. [The Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21413 (Saudi Arabia); Wu, J.J., E-mail: jjwu@fcu.edu.tw [Department of Environmental Engineering and Science, Feng Chia University, Taichung 407, Taiwan (China)

    2017-06-15

    Highlights: • Copper ferrite (CuFe{sub 2}O{sub 4}) nanoparticles were synthesized via citrate-nitrate combustion method. • Spectroscopic information’s have found that CuFe{sub 2}O{sub 4} nanoparticles as an inverse spinel structure. • Magnetic study exhibits CuFe{sub 2}O{sub 4} nanoparticles have ferromagnetic behavior. • CuFe{sub 2}O{sub 4} nanoparticles employed for photocatalytic decolourisation of methylene blue under visible light irradiation. - Abstract: In this research, inverse spinel copper ferrite nanoparticles (CuFe{sub 2}O{sub 4} NPs) were synthesized via citrate-nitrate combustion method. The crystal structure, particle size, morphology and magnetic studies were investigated using various instrumental tools to illustrate the formation of the inverse spinel structure. Mossbauer spectrometry identified Fe is located both in the tetrahedral and octahedral site in the ratio (40:60) and the observed magnetic parameters values such as saturation magnetization (M{sub s} = 20.62 emu g{sup −1}), remnant magnetization (M{sub r} = 11.66 emu g{sup −1}) and coercivity (H{sub c} = 63.1 mTesla) revealed that the synthesized CuFe{sub 2}O{sub 4} NPs have a typical ferromagnetic behaviour. Also tested CuFe{sub 2}O{sub 4} nanoparticles as a photocatalyst for the decolourisation of methylene blue (MB) in the presence of peroxydisulphate as the oxidant.

  12. Improvement of Thermal Stability of Nd-Tb-Fe-Co-B Sintered Magnets by Additions of Pr, Ho, Al, and Cu

    Directory of Open Access Journals (Sweden)

    A. A. Lukin

    2012-01-01

    Full Text Available The present work investigates the influence of Pr, Al, Cu, B and Ho which were introduced into the Co-containing sintered magnets of Nd-Dy-Tb-Fe-Co-B type on the magnetic parameters (α, Hci, Br, BHmax⁡. The effect of heat treatment parameters on magnetic properties was also studied. It was revealed that the essential alloying of NdFeB magnets by such elements as Dy, Tb, Ho, Co as well as by boron-forming elements, for example, by titanium, may lead to reducing of F-phase quantity, and, as a consequence, to decreasing of magnetic parameters. It was also shown that additional doping of such alloys by Pr, B, Al and Cu leads to a significant increase of the quantity of F-phase in magnets as well as solubility of the Dy, Tb, Ho and Co in it. This promotes the increase of magnetic parameters. It was possible to attain the following properties for the magnets (Nd0,15Pr0,35Tb0,25Ho0,2515(Fe0,71Co0,29bal ⋅ Al0,9Cu0,1B8,5 (at. % after optimal thermal treatment {1175 K (3,6–7,2 ks with slow (12–16 ks cooling to 675 K and subsequently remaining at T=775 K for 3,6 ks—hardening}: Br=0,88 T, Hci=1760 kA/m, BHmax⁡=144 kJ/m3, α<|0,01|%/K in the temperature interval 223–323 K.

  13. Magnetic properties in BiFeO{sub 3} doped with Cu and Zn first-principles investigation

    Energy Technology Data Exchange (ETDEWEB)

    Rong, Qing-Yan [School of Physics and Electronics, Hunan University, Changsha 410082 (China); Department of Physics and Mathematics, Hunan Institute of Engineering, Xiangtan 411104 (China); Xiao, Wen-Zhi, E-mail: xiaowenzhi@hnu.edu.cn [School of Physics and Electronics, Hunan University, Changsha 410082 (China); Department of Physics and Mathematics, Hunan Institute of Engineering, Xiangtan 411104 (China); Xiao, Gang [School of Physics and Electronics, Hunan University, Changsha 410082 (China); Department of Physics and Mathematics, Hunan Institute of Engineering, Xiangtan 411104 (China); Hu, Ai-Ming [Department of Physics and Mathematics, Hunan Institute of Engineering, Xiangtan 411104 (China); Wang, Ling-Ling, E-mail: llwang@hnu.edu.cn [School of Physics and Electronics, Hunan University, Changsha 410082 (China)

    2016-07-25

    Based on first-principles spin-polarized density functional theory calculations, the electronic structures, and magnetic properties of Cu and Zn-doped BiFeO{sub 3} are investigated. The calculated formation energies show that Cu prefers to occupy Fe site, while the Zn prefer to occupy Bi site. All the doped BiFeO{sub 3} systems turn out to be favorable for G-type antiferromagnetic arrangement. The substitution of Cu and Zn for Fe produces a magnetic moment of 3.0 and 4.0 μ{sub B} per dopant, respectively. The net magnetic moments are from the broken symmetry of the AFM spin ordering network. For the substitution of Cu and Zn for Bi, the net magnetic moment originates from Cu/Zn itself and hole introduced by Cu/Zn. Two-Cu/Zn-doped cases show various magnetic behaves. If O vacancy is far away from dopants, the O vacancies don't affect the net magnetic moment of the substitution of Cu and Zn for Fe, but have notable effect for Bi site doping. The O vacancies result in metallicity in all doped cases. Our study demonstrates that the nonmagnetic Cu and Zn doping will lead to the diversity and complexity of magnetic properties depending on doping sites, distance between dopants, intrinsic defect, and so on, which could be responsible for the observed various magnetic behaviors in Cu/Zn-doped BiFeO{sub 3} samples. - Highlights: • The Fe site doping produces magnetic moments, due to the breaking of the symmetry. • The Bi site doping produces magnetic moments which originate from unpaired holes. • Different substitutions of Cu/Zn for Fe result in various magnetic properties. • The O vacancies make all the doped samples metallic and affect magnetic properties.

  14. Hysteresis effect of ammonium and water protons by 1H MAS NMR in (NH4)2CuBr4·2H2O

    Science.gov (United States)

    Lim, Ae Ran; Cho, Jiung

    2017-10-01

    The chemical shifts, linewidths, and spin-lattice relaxation times for ammonium and water protons in (NH4)2CuBr4·2H2O were investigated by 1H magic angle spinning nuclear magnetic resonance (MAS NMR) with a focus on the roles of NH4+ and H2O at high temperatures. The changes in the temperature dependence of the data near Td (=360 K) were related to variations of the H environments; the mechanism above Td was related to hydrogen-bond transfer involving breakage of the weak part of the hydrogen bond. The hysteresis effects for the ammonium and water protons in (NH4)2CuBr4·2H2O by MAS NMR were described with respect to heating and cooling.

  15. A Novel Ternary CoFe2O4/CuO/CoFe2O4 as a Giant Magnetoresistance Sensor

    Directory of Open Access Journals (Sweden)

    Ramli

    2016-12-01

    Full Text Available This paper reports the results of a study relating to the synthesis of a novel ternary CoFe2O4/CuO/CoFe2O4 thin film as a giant magnetoresistance (GMR sensor. The CoFe2O4/CuO/CoFe2O4 thin film was prepared onto silicon substrate via DC magnetron sputtering with the targets facing each other. X-ray diffraction was used to determine the structure of the thin film and a 4-point method was used to measure the MR ratio. The GMR ratio is highly dependent on the ferrimagnetic (CoFe2O4 and nonmagnetic (CuO layer thickness. The maximum GMR ratio at room temperature obtained in the CoFe2O4/CuO/CoFe2O4 thin film was 70% when the CoFe2O4 and the CuO layer had a thickness of 62.5 nm and 14.4 nm respectively.

  16. Spontaneous piezoelectric effect as order parameter in (NH{sub 4}){sub 2}CuBr{sub 4}·2H{sub 2}O crystal

    Energy Technology Data Exchange (ETDEWEB)

    Tylczyński, Z., E-mail: zbigtyl@amu.edu.pl; Wiesner, M.; Trzaskowska, A.

    2016-11-01

    Temperature change of piezoelectric properties of (NH{sub 4}){sub 2}CuBr{sub 4}·2H{sub 2}O crystal in the low-temperature ferroelastoelectric phase is studied. The macroscopic order parameter is proved to be the h{sub 36} component of the spontaneous piezoelectric tensor. The critical exponent related with the phase transition is α=0.60±0.05.

  17. Anisotropic lattice dynamics and intermediate-phase magnetism in delafossite CuFeO2

    Science.gov (United States)

    Klobes, B.; Herlitschke, M.; Rushchanskii, K. Z.; Wille, H.-C.; Lummen, T. T. A.; van Loosdrecht, P. H. M.; Nugroho, A. A.; Hermann, R. P.

    2015-07-01

    Hyperfine interactions and Fe-specific lattice dynamics in CuFeO2 were investigated by nuclear resonance scattering methods and compared to ab initio lattice dynamics calculations. Using nuclear forward scattering the collinear spin structure at temperatures below about 11 K could be confirmed, whereas the nuclear forward scattering results in the intermediate temperature range between about 11 K and 14 K are incompatible with the assumption of a sinusoidal distribution of spins parallel to the c axis of CuFeO2. The critical behavior of the average hyperfine field at the phase transition at about 14 K further supports a three-dimensional model for the magnetism in this compound. Moreover, using nuclear inelastic scattering by the 57 Fe Mössbauer resonance, Fe-specific lattice dynamics are found to be strongly anisotropic with stiffer bonds in the a b plane of the crystal. The powder averaged, Fe partial density of phonon states can be well modeled using ab initio calculations and low-energy phonons are found to deviate from classical Debye-like behavior, indicating spin-phonon coupling in this compound. Besides, the theoretical phonon spectrum exhibits typical characteristics for delafossite-type material.

  18. Solid state interactions in the systems CaO(CaCO3-Fe2O3 and CuFe2O4-CaO

    Directory of Open Access Journals (Sweden)

    Boyanov B.S.

    2005-01-01

    Full Text Available The solid state interactions in the systems CaO(CaCO3-Fe2O3 and CuFe2O4-CaO have been studied using X-ray diffraction analysis. The influence of the temperature on the ferrite formation process has been investigated in the range of 900-1200 oC and duration up to 360 min. It has been shown that a mixture of ferrites forms at 1000 oC and interaction of 240 min. The exchange reactions in the systems CuFe2O4-CaO and Cu0.5Zn0.5Fe2O4-CaO have been studied, too. It has been established that Ca2+ ions exchange Cu2+ and Zn2 partially and the solubility of copper and zinc in a 7 % sulfuric acid solution increases 10-15 times.

  19. Positron Annihilation Spectroscopy and Small Angle Neutron Scattering Characterization of Nanostructural Features in Irradiated Fe-Cu-Mn Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wirth, B D; Asoka-Kumar, P; Howell, R H; Odette, G R; Sterne, P A

    2001-01-01

    Radiation embrittlement of nuclear reactor pressure vessel steels results from a high number density of nanometer sized Cu-Mn-Ni rich precipitates (CRPs) and sub-nanometer matrix features, thought to be vacancy-solute cluster complexes (VSC). However, questions exist regarding both the composition of the precipitates and the defect character and composition of the matrix features. We present results of positron annihilation spectroscopy (PAS) and small angle neutron scattering (SANS) characterization of irradiated and thermally aged Fe-Cu and Fe-Cu-Mn alloys. These complementary techniques provide insight into the composition and character of both types of nanoscale features. The SANS measurements indicate populations of CRPs and VSCs in both alloys. The CRPs are coarser in the Fe-Cu alloy and the number densities of CRP and VSC increase with the addition of Mn. The PAS involved measuring both the positron lifetimes and the Doppler broadened annihilation spectra in the high momentum region to provide elemental sensitivity at the annihilation site. The spectra in Fe-Cu-Mn specimens thermally aged to peak hardness at 450 C and irradiated at 288 C are nearly identical to elemental Cu. Positron lifetime and spectrum measurements in Fe-Cu specimens irradiated at 288 C clearly show the existence of long lifetime ({approx}500 ps) open volume defects, which also contain Cu. Thus the SANS and PAS provide a self-consistent picture of nanostructures composed of CRPs and VSCs and tend to discount high Fe concentrations in the CRPs.

  20. Fluorescent and colorimetric detection of Fe(III) and Cu(II) by a difunctional rhodamine-based probe

    Science.gov (United States)

    Wang, Lei; Ye, Dandan; Li, Wenxuan; Liu, Yuanyuan; Li, Longhua; Zhang, Wenli; Ni, Liang

    2017-08-01

    A new rhodamine B hydrazone derivative (probe L) was synthesized and characterized. The probe L had sufficiently satisfactory selective response to Fe3 + and Cu2 + ions among various interferential metal ions, and high sensitivity with the detection limit of 4.63 × 10- 9 M and 5.264 × 10- 7 M for Fe3 + and Cu2 + ions, respectively. In the presence of Fe3 +, the probe L exhibited turn-on orange fluorescence accompanied by color change from colorless to pink. Toward Cu2 +, the probe L showed significant color change from colorless to red purple. These remarkable orange fluorescence and color change made probe L suitable naked-eye identify for Fe3 + and Cu2 + ions. By means of Job's plot, Benesi-Hildebrand studies and FTIR spectra, both 1:1 binding modes (L-Fe3 + and L-Cu2 +) were confirmed. The coordination mechanism and turn on/off fluorescence for L-Fe3 + and L-Cu2 + complexes were well explained by theoretical calculations. Moreover, probe L could be used as a quick, simple, visual test strip for Fe3 + and Cu2 + detection.

  1. The properties of Mn-CuFe2O4 spinel ferrite nanoparticles under various synthesis conditions

    Science.gov (United States)

    Kamzin, A. S.; Ranjith Kumar, E.; Ramadevi, P.; Selvakumar, C.

    2017-09-01

    The structural, morphological, magnetic, dielectric, and gas analyzing properties are studied in CuFe2O4(Mn-CuFe2O4) substituted spinel ferrite nanoparticles synthesized via evaporation and automatic combustion. The obtained nanoparticles are established to possess a spherical shape. The smallest size of Mn-CuFe2O4 ( 9 nm) nanoparticles is achieved at using automatic combustion. X-ray diffraction and Mössbauer spectroscopy reveal that the crystal lattice constant and the Mn-CuFe2O4 nanoparticle size are larger at augmenting the annealing temperature from 600 to 900°C. The dielectric permeability and losses of Mn-CuFe2O4 nanoparticles are studied at various synthesis conditions and temperatures of annealing. Various aspects of gas sensibility of synthesized Mn-CuFe2O4 nanoparticles are tested, as well. The maximum response to the presence of liquefied petroleum gas is 0.28 at the optimum working temperature of 300°C for Mn-CuFe2O4 nanoparticles obtained via automatic combustion and it is 0.23 at 250°C for deposited nanoparticles.

  2. Raman scattering study of delafossite magnetoelectric multiferroic compounds: CuFeO2 and CuCrO2

    OpenAIRE

    Aktas, O.; Truong, K D; Otani, T; G. Balakrishnan; Clouter, M. J.; Kimura, T; Quirion, G.

    2011-01-01

    Ultrasonic velocity measurements on the magnetoelectric multiferroic compound CuFeO2 reveal that the antiferromagnetic transition observed at TN1 = 14 K might be induced by an R-3m -> C2/m pseudoproper ferroelastic transition (G. Quirion, M. J. Tagore, M. L. Plumer, O. A. Petrenko, Phys. Rev. B 77, 094111 (2008)). In that case, the group theory states that the order parameter associated with the structural transition must belong to a two dimensional irreducible representation Eg (x^2 - y^2, x...

  3. Colloidal CuFeS2 Nanocrystals: Intermediate Fe d-Band Leads to High Photothermal Conversion Efficiency

    CERN Document Server

    Ghosh, S; Petrelli, A; Kriegel, I; Gaspari, R; Almeida, G; Bertoni, G; Cavalli, A; Scotognella, F; Pellegrino, T; Manna, L

    2016-01-01

    We describe the colloidal hot-injection synthesis of phase-pure nanocrystals (NCs) of a highly abundant mineral, chalcopyrite (CuFeS2). Absorption bands centered at around 480 and 950 nm, spanning almost the entire visible and near infrared regions, encompass their optical extinction characteristics. These peaks are ascribable to electronic transitions from the valence band (VB) to the empty intermediate band (IB), located in the fundamental gap and mainly composed of Fe 3d orbitals. Laser-irradiation (at 808 nm) of an aqueous suspension of CuFeS2 NCs exhibited significant heating, with a photothermal conversion efficiency of 49%. Such efficient heating is ascribable to the carrier relaxation within the broad IB band (owing to the indirect VB-IB gap), as corroborated by transient absorption measurements. The intense absorption and high photothermal transduction efficiency (PTE) of these NCs in the so-called biological window (650-900 nm) makes them suitable for photothermal therapy as demonstrated by tumor ce...

  4. Photochromic conversions of the Br/sub 2//sup -/ radical ion

    Energy Technology Data Exchange (ETDEWEB)

    Plyusnin, V.F.

    The photolysis of frozen solutions of HBr, containing complexes of FeBr/sub 3/ or CuBr/sub 4//sup 2 -/, is discussed. The primary product of the photoreduction of complexes is the radical ion Br/sub 2//sup -/. Irradiation in the absorption band of this particle leads to its disappearance. However, it can be regulated by photolysis of the sample in a shorter-wave region of the spectrum. The processes leading to this photochrome conversion are discussed.

  5. Effects of Ge substitution on the structural and physical properties of CuFeO2 delafossite oxide

    Science.gov (United States)

    Naka-in, Lerdkead; Kamwanna, Teerasak; Srepusharawoot, Pornjuk; Pinitsoontorn, Supree; Amornkitbamrung, Vittaya

    2015-04-01

    Delafossite CuFe1-xGexO2 (0.0 ≤ x ≤ 0.1) semiconductors were synthesized by solid-state reaction. The effects of Ge concentration on microstructural, optical, magnetic and electrical properties were investigated. X-ray diffraction (XRD) analysis results reveal the delafossite structure of all the samples. The lattice spacing of CuFe1-xGexO2 decreased with increasing substitution of Ge at the Fe site. The optical properties measured at room temperature by UV-visible spectroscopy showed an absorption peak at 283 nm (4.38 eV). The corresponding direct optical band gap was found to decrease with increasing Ge content (from 3.69 eV for x = 0 to 3.61 eV for x = 0.10), exhibiting transparency in the visible region. The magnetic hysteresis loops measured at room temperature showed that the Ge-doped CuFeO2 samples exhibit ferromagnetic behavior. The Curie temperature suggests that ferromagnetism originates from CuFe1-xGexO2 matrices. The substitution of Fe3+ by Ge4+ produces a mixed effect on the magnetic properties of CuFeO2 delafossite oxide. The resistivity of CuFe0.99Ge0.01O2 was observed to be ˜0.1 Ω·cm at room temperature.

  6. Formation of C2oxygenates and ethanol from syngas on an Fe-decorated Cu-based catalyst: insight into the role of Fe as a promoter.

    Science.gov (United States)

    Ling, Lixia; Wang, Qiang; Zhang, Riguang; Li, Debao; Wang, Baojun

    2017-11-22

    In this study, the formation mechanism of C 2 oxygenates and ethanol from syngas on Fe-decorated Cu bimetallic catalyst was investigated using density functional theory (DFT) calculations together with microkinetic modeling. The results showed that CH 2 was the most favored monomer among all the CH x (x = 1-3) species over the FeCu bimetallic catalyst, which was more favorable than CH 3 OH formation. Namely, the FeCu catalyst exhibited a good selectivity toward CH 2 formation instead of CH 3 OH formation in syngas conversion. Starting from the CH 2 monomer, CH 2 CO and CH 3 CO via CO insertion into CH 2 and CH 2 CO hydrogenation were the major products instead of C 2 hydrocarbons or methane, CH 3 CO was successively hydrogenated to ethanol via CH 3 CHO and CH 3 CH 2 O intermediates. Moreover, the microkinetic modeling showed that the FeCu bimetallic catalyst had a high selectivity toward ethanol rather than methanol and methane. Further, the addition of Fe into the Cu catalyst promoted CH x formation by accelerating C-O bond cleavage, suppressed methanol formation, and facilitated C 2 oxygenate formation rather than methane formation, suggesting that the synergetic effect between Fe and Cu played an important role in the formation of C 2 oxygenates and ethanol. In addition, it is believed that the insights derived from this study can provide clues for the catalyst design of oxygenate synthesis and other bimetallic catalytic systems.

  7. Synthesis and magnetic properties of multilayer Ni/Cu and NiFe/Cu ...

    Indian Academy of Sciences (India)

    electron microscopy (TEM), magnetic force microscopy (MFM), and vibrating sample magnetometer (VSM) measurements. The MFM images indicate that every ferromagnetic layer separated by Cu layer was present as single isolated domain-like magnet. This technique has potential use in the measurement and application ...

  8. Cu and Fe Isotope Variation in Candelaria Sulfides: Tracing to Origin of Fluid Components in a Stratiform Ore Deposit

    Science.gov (United States)

    Graham, S.; Griffin, W.; Pearson, N.; Jackson, S.; O'Reilly, S.; Rutherford, R.

    2004-05-01

    We have used LA-MC-ICPMS to determine Cu and Fe isotope ratios in chalcopyrite and pyrite from a stratigraphic section through the stratiform Candelaria Cu-Au deposit. Chalcopyrite ɛ 65Cu range from -11 to +6 (n = 85), many of which are 65Cu depleted when compared to chalcopyrite from igneous porphyry systems. However, chalcopyrite from the Candelaria open-pit have ɛ 65Cu overlapping porphyry systems, suggesting an igneous source for the Cu in the massive ore. Very low ɛ 65Cu in sequences above the Candelaria open-pit may reflect the vapor transport of Cu, or fluid mixing. Chalcopyrite ɛ 57Fe range from -22 to +4 (n = 102), but the majority cluster between -22 and -8, and are indistinguishable from those in porphyry deposits. In contrast, the ɛ 57Fe of pyrite (n = 111) show a bi-modal distribution, with ɛ 57Fe ranging between -25 to -10 and -2 to +15. The high ɛ 57Fe are indistinguishable from igneous porphyry pyrite (ɛ 57Fe = 0 to +12) and provide unambiguous evidence for the involvement of an igneous component in Candelaria ore genesis. However, the low ɛ 57Fe pyrites also suggest the involvement of another Fe source. Three samples, from the west, central and eastern zones of the Candelaria open-pit show evidence for interaction between the igneous and, presumably, crustal fluids. Chalcopyrite and pyrite from the western-most sample, near a shear zone, have Cu and Fe isotope variations similar to those observed in igneous porphyry deposits. In contrast, chalcopyrite and pyrite from the eastern-most sample, near a major fault, have an igneous-like ɛ 65Cu, but the chalcopyrite and pyrite ɛ 57Fe are unlike that observed in porphyry systems. The Cu and Fe isotope variations of the central sample are intermediate between the western and eastern samples. These variations undoubtedly result from mixing between Fe from an igneous fluid from the shear zone and Fe from a crustal fluid from the fault zone.

  9. Negative magnetoresistance in an antiferromagnetic metal β″-(EDO-TTFVODS) 2FeBr 4(DCE) 0.5

    Science.gov (United States)

    Weng, Yufeng; Yoshino, Harukazu; Fujiwara, Hideki; Sugimoto, Toyonari; Murata, Keizo

    2008-12-01

    An organic conductor β″-(EDO-TTFVODS) 2FeBr 4(DCE) 0.5, where EDO-TTFVODS is ethylenedioxytetrathiafulvalenoquinone-1,3-diselenolemethide and DCE is 1,2-dichloroethane, has been synthesized and is expected to have a strong π-d interaction. It was found that the material is metallic down to about 4 K and shows a rather slight upturn of electrical resistivity ρ below this temperature. Temperature dependence of ρ in the slight upturn region is proportional to log T and weak negative magnetoresistance (-1.7%, 2 T) at 1.4 K also appears. Besides π-d interaction screened by conducting electrons in this material, weak localization and Kondo effect are also possible to explain this negative magnetoresistance. Oscillatory behavior probably due to a quasi-two-dimensional (Q2D) Fermi surface was observed in the field-orientation dependence, and kF‖ b' was estimated to be 0.19 Å -1.

  10. Wear behavior of self-lubricating Fe-Cr-C-Mn-Cu alloys: Smearing effect of second phase particles

    Science.gov (United States)

    Kim, Ki Nam; Kim, Byung Sik; Shin, Gyeong Su; Park, Myung Chul; Lee, Deok Hyun; Kim, Seon Jin

    2011-08-01

    Newly developed self-lubricating Fe-Cr-C-Mn-Cu cast composite alloys were investigated to study the role of Cu-rich second phase particles which smear on the wear surface during sliding. The wear resistance of the material was improved with an increasing copper concentration. The improved wear resistance was probably obtained by forming a protective tribofilm, which prevented metal-to-metal contact through smearing of the embedded Cu-rich second phase particles. This formation of protective oxide films during sliding is likely to improve the wear resistance of austenitic Fe-Cr-C-Mn-Cu cast composite alloys.

  11. Fabrication and mechanical properties of AlCoNiCrFe high-entropy alloy particle reinforced Cu matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jian, E-mail: chenjian@xatu.edu.cn [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Niu, Pengyun; Wei, Ting [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Hao, Liang [College of Architecture and Civil Engineering, Xi' an University of Science and Technology, Xi' an 710054 (China); Liu, Yunzi [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Wang, Xianhui, E-mail: xhwang693@xaut.edu.cn [School of Materials Science and Engineering, Xi' an University of Technology, Xi' an, Shaanxi 710048 (China); Peng, Yuli [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China)

    2015-11-15

    The AlCoNiCrFe high-entropy alloy was prepared by mechanical alloying and the AlCoNiCrFe high-entropy alloy reinforced Cu matrix composites were subsequently fabricated by powder metallurgy. The phase constituents and morphology of the alloying powders were characterized by X-ray diffractometer and scanning electron microscope, the microstructures of the Cu base composites were characterized by scanning electron microscope and transmission electron microscope, and the compression tests were made as well. The results show that the AlCoNiCrFe high-entropy alloy can form after milling for 24 h. During sintering process, no grain growth occurs and no intermetallic phases present in the AlCoNiCrFe high-entropy alloy in the Cu base composite. Compression tests show that the AlCoNiCrFe high-entropy alloy has a better strengthening effect than metallic glasses and the yield strength of the Cu matrix composite reinforced with the AlCoNiCrFe high-entropy alloy is close to the value predicted by the Voigt model based on the equal strain assumption. - Graphical abstract: AlCoNiCrFe HEA has a better strengthening effect than metallic glasses for particulate reinforced metal matrix composites. The yield strength of the Cu base composite reinforced with the AlCoNiCrFe HEA is close to the upper bound calculated by Voigt model. - Highlights: • AlCoNiCrFe high-entropy alloy was prepared by mechanical alloying. • A novel Cu base composite reinforced with AlCoNiCrFe was fabricated. • No grain growth and no intermetallic phase present in AlCoNiCrFe during sintering. • AlCoNiCrFe has a better strengthening effect than metallic glassy in composites.

  12. Subsurface structure and magnetic parameters of Fe-Mo-Cu-B metallic glass

    Directory of Open Access Journals (Sweden)

    Miglierini Marcel

    2015-03-01

    Full Text Available Subsurface properties of 57Fe81Mo9Cu1B9 metallic glass were studied by conversion electron and conversion X-ray Mössbauer spectrometry. They were applied to both surfaces of the ribbons. Deviations in structural surface features are exhibited via different contents of crystalline phases, which were identified as bcc-Fe and magnetite. The presence of small ferromagnetic particles was also suggested from magnetic measurements. An influence of irradiation with 130-keV N+ ions on surface properties of the as-quenched alloy is also discussed.

  13. Measurements of the work function of single-walled carbon nanotubes encapsulated by AgI, AgCl, and CuBr using Kelvin probe technique with different kinds of probes

    Energy Technology Data Exchange (ETDEWEB)

    Zhukov, A. A., E-mail: azhukov@issp.ac.ru [Russian Academy of Science, Institute of Solid State Physics (Russian Federation); Chernysheva, M. V.; Eliseev, A. A. [Moscow State University, Department of Materials Science (Russian Federation)

    2016-07-15

    We report the results on the measurements of the work function of single-walled carbon nanotubes encapsulated by Agl (AgI@SWCNT), AgCl (AgCl@SWCNT), and CuBr (CuBr@SWCNT) by the local Kelvin probe technique. We found the values of the work function of tubes encapsulated with AgI and AgCl (Φ(AgI@SWCNT) = 5.08 ± 0.02, Φ(AgCl@SWCNT) = 5.10 ± 0.02 eV) to exceed substantially that of pristine carbon nanotubes, and the value of the work function of carbon nanotubes encapsulated with CuBr is Φ(CuBr@SWCNT) = 4.89 ± 0.03 (eV). The measurements are carried out using different kinds of microscope probes including multi-walled carbon nanotube tips.

  14. Mechanism of charge transfer/disproportionation in LnCu3Fe4O12 (Ln = lanthanides)

    Science.gov (United States)

    Rezaei, N.; Hansmann, P.; Bahramy, M. S.; Arita, R.

    2014-03-01

    The Fe-Cu intersite charge transfer and Fe charge disproportionation are interesting phenomena observed in some LnCu3Fe4O12 (Ln = lanthanides) compounds containing light and heavy Ln atoms, respectively. We show that a change in the spin state is responsible for the intersite charge transfer in the light Ln compounds. At the high-spin state, such systems prefer an unusual Cu d8 configuration, whereas at the low-spin state they retreat to the normal Cu d9 configuration through a charge transfer from Fe to the Cu 3dxy orbital. We find that the strength of the crystal-field splitting and the relative energy ordering between Cu 3dxy and Fe 3d states are the key parameters determining the intersite charge transfer (charge disproportionation) in light (heavy) Ln compounds. It is further proposed that the size of Ln affects the on-site interaction strength of Cu 3d states, leading to a strong modification of the Cu L3-edge spectrum, as observed by the x-ray-absorption spectroscopy.

  15. Influences of post-annealing conditions on the formation of delafossite-CuFeO2 thin films

    Science.gov (United States)

    Chen, Hong-Ying; Fu, Guan-Wei

    2014-01-01

    In this study, post-annealing conditions, the partial oxygen pressures (pO2) and temperatures, influence on the formation of delafossite-CuFeO2 thin films is studied. The sol-gel derived films were annealed at 500 °C in air and post-annealed at 500-850 °C in pO2 = 10-2 to pO2 = 5 × 10-5 atm. The CuO and CuFe2O4 phases appeared when the sol-gel derived films were post-annealed below 800 °C for 2 h in pO2 = 10-2 atm, 650 °C for 2 h in pO2 = 10-3 atm, and 550 °C for 2 h in pO2 = 5 × 10-5 atm. Pure delafossite-CuFeO2 phase was detected as specimens were post-annealed above 800 °C for 12 h in pO2 = 10-2 atm, 650 °C for 12 h in pO2 = 10-3 atm, and 550 °C for 12 h in pO2 = 5 × 10-5 atm. The surface of post-annealed thin films exhibited a nanoparticle-like morphology when the specimens exhibited CuO and CuFe2O4 phases. However, the surface revealed granular features caused by the formation of the delafossite-CuFeO2 phase. The formation of the delafossite-CuFeO2 phase, which resulted from the chemical reaction of the CuO and CuFe2O4 phases in the post-annealing process, is consistent with thermodynamics. The optical bandgaps of delafossite-CuFeO2 thin films prepared using post-annealing ranged between 3.1 and 3.2 eV. The electrical conductivities of delafossite-CuFeO2 thin films were (1.62-6.37) × 10-1 S cm-1 and the carrier concentrations were (1.52-8.84) × 1017 cm-3. The pO2 and temperatures in the post-annealing process played primary roles in the formation of delafossite-CuFeO2 thin films in this study.

  16. Influences of post-annealing conditions on the formation of delafossite–CuFeO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hong-Ying, E-mail: hychen@cc.kuas.edu.tw; Fu, Guan-Wei

    2014-01-01

    In this study, post-annealing conditions, the partial oxygen pressures (pO{sub 2}) and temperatures, influence on the formation of delafossite–CuFeO{sub 2} thin films is studied. The sol–gel derived films were annealed at 500 °C in air and post-annealed at 500–850 °C in pO{sub 2} = 10{sup −2} to pO{sub 2} = 5 × 10{sup −5} atm. The CuO and CuFe{sub 2}O{sub 4} phases appeared when the sol–gel derived films were post-annealed below 800 °C for 2 h in pO{sub 2} = 10{sup −2} atm, 650 °C for 2 h in pO{sub 2} = 10{sup −3} atm, and 550 °C for 2 h in pO{sub 2} = 5 × 10{sup −5} atm. Pure delafossite–CuFeO{sub 2} phase was detected as specimens were post-annealed above 800 °C for 12 h in pO{sub 2} = 10{sup −2} atm, 650 °C for 12 h in pO{sub 2} = 10{sup −3} atm, and 550 °C for 12 h in pO{sub 2} = 5 × 10{sup −5} atm. The surface of post-annealed thin films exhibited a nanoparticle-like morphology when the specimens exhibited CuO and CuFe{sub 2}O{sub 4} phases. However, the surface revealed granular features caused by the formation of the delafossite–CuFeO{sub 2} phase. The formation of the delafossite–CuFeO{sub 2} phase, which resulted from the chemical reaction of the CuO and CuFe{sub 2}O{sub 4} phases in the post-annealing process, is consistent with thermodynamics. The optical bandgaps of delafossite–CuFeO{sub 2} thin films prepared using post-annealing ranged between 3.1 and 3.2 eV. The electrical conductivities of delafossite–CuFeO{sub 2} thin films were (1.62–6.37) × 10{sup −1} S cm{sup −1} and the carrier concentrations were (1.52–8.84) × 10{sup 17} cm{sup −3}. The pO{sub 2} and temperatures in the post-annealing process played primary roles in the formation of delafossite–CuFeO{sub 2} thin films in this study.

  17. Simultaneous oxidation of EDTA and reduction of metal ions in mixed Cu(II)/Fe(III)-EDTA system by TiO2 photocatalysis.

    Science.gov (United States)

    Park, Eun-Hee; Jung, Jinho; Chung, Hung-Ho

    2006-06-01

    Both the photooxidation of EDTA and the photoreduction of metal ions in metal-EDTA systems were investigated. EDTA oxidation by TiO(2) photocatalysis occurred sequentially as Cu(II)-EDTA>Cu(II)/Fe(III)-EDTA>Fe(III)-EDTA. For Cu(II)-EDTA, EDTA was completely decomposed after only 60min of irradiation. The rate of EDTA decomposition was directly correlated with the initial Cu(II) concentration in the case of a mixed Cu(II)/Fe(III)-EDTA system. The metal ions in a single metal-EDTA complex were removed following significant decomposition of EDTA. For a mixed Cu(II)/Fe(III)-EDTA system, however, no copper was removed whereas almost all of the iron was removed. The iron and copper species deposited on the TiO(2) surface were identified via EPR and XPS as mixed FeO/Fe(3)O(4) and Cu(0)/Cu(2)O, respectively.

  18. Hydrothermal synthesis and characterization of CuFeO2 Delafossite Crystals

    Science.gov (United States)

    Sarabia, M.; Rojas, S.; Lopez-Cabana, Z.; Villalba, R.; Gonzalez, G.; Cabrera, A. L.

    2015-03-01

    In this study we synthetized CuFeO2 compounds using as precursors Cu2O and FeOOH with fused NaOH. The synthesis takes place is a Teflon vessel lasting 97 (Synthesis I) or 48 hrs (Synthesis II) at 210 °C. The compound obtained were analyzed for crystal structure and morphology with Raman Sprectroscopy, X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS). Optical properties were obtained by UV-Vis Spectroscopy and Gas adsorption measured with a Quartz-Crystal Microbalance (QCM). Our results show that this type of hydrothermal synthesis is capable to recreate the Delafossite structure of this copper-iron oxide. This material chemisorbs water and carbon dioxide. Funds FONDECyT 1130372.

  19. Dilute Magnetic Semiconductor Cu2FeSnS4 Nanocrystals with a Novel Zincblende Structure

    Directory of Open Access Journals (Sweden)

    Xiaolu Liang

    2012-01-01

    Full Text Available Diluted magnetic semiconductor Cu2FeSnS4 nanocrystals with a novel zincblende structure have been successfully synthesized by a hot-injection approach. Cu+, Fe2+, and Sn4+ ions occupy the same position in the zincblende unit cell, and their occupancy possibilities are 1/2, 1/4, and 1/4, respectively. The nanocrystals were characterized by means of X-ray diffraction (XRD, transmission electron microscopy (TEM, selected area electron diffraction (SAED, energy-dispersive spectroscopy (EDS, and UV-vis-NIR absorption spectroscopy. The nanocrystals have an average size of 7.5 nm and a band gap of 1.1 eV and show a weak ferromagnetic behavior at low temperature.

  20. Synthesis of multiwalled carbon nanotubes on Cu-Fe nano-catalyst substrate

    Science.gov (United States)

    Rezaee, Sahar; Ghaderi, Atefeh; Boochani, Arash; Solaymani, Shahram

    Considering the importance of metal nano catalysts, this research tries to apply sputtered nanoparticles as catalyst for growing carbon nanotubes and studies the effect of metals in modifying the catalytic property. One and bilayer Cu and Fe thin films were placed inside a quartz tube reactor to synthesis carbon nanotubes using acetylene gas as carbon source and argon gas for cooling down the reactor from 850 °C to room temperature. By scanning electron microscope images distribution of diameter of multi walled carbon nanotubes has recorded. The amounts of ID/IG obtained from Raman spectroscopy analysis showed the best quality of carbon nanotubes for Cu-Fe bilayer. Both analyses indicate the improve of catalytic effect of one transition metal by another one. On the other hand, multi walled carbon nanotubes are confirmed by both Raman spectroscopy and transmission electron microscopy images.

  1. Synthesis of multiwalled carbon nanotubes on Cu-Fe nano-catalyst substrate

    Directory of Open Access Journals (Sweden)

    Sahar Rezaee

    Full Text Available Considering the importance of metal nano catalysts, this research tries to apply sputtered nanoparticles as catalyst for growing carbon nanotubes and studies the effect of metals in modifying the catalytic property. One and bilayer Cu and Fe thin films were placed inside a quartz tube reactor to synthesis carbon nanotubes using acetylene gas as carbon source and argon gas for cooling down the reactor from 850 °C to room temperature. By scanning electron microscope images distribution of diameter of multi walled carbon nanotubes has recorded. The amounts of ID/IG obtained from Raman spectroscopy analysis showed the best quality of carbon nanotubes for Cu-Fe bilayer. Both analyses indicate the improve of catalytic effect of one transition metal by another one. On the other hand, multi walled carbon nanotubes are confirmed by both Raman spectroscopy and transmission electron microscopy images. Keywords: Transition metal nano catalyst, TCVD, MWCNT, Raman spectroscopy

  2. Simulations of irradiated-enhanced segregation and phase separation in Fe-Cu-Mn alloys

    Science.gov (United States)

    Li, Boyan; Hu, Shenyang; Li, Chengliang; Li, Qiulin; Chen, Jun; Shu, Guogang; Henager, Chuck, Jr.; Weng, Yuqing; Xu, Ben; Liu, Wei

    2017-09-01

    For reactor pressure vessel steels, the addition of Cu, Mn, and Ni has a positive effect on their mechanical, corrosion and radiation resistance properties. However, experiments show that radiation-enhanced segregation and/or phase separation is one of the important material property degradation processes. In this work, we develop a model integrating rate theory and phase-field approaches to investigate the effect of irradiation on solute segregation and phase separation. The rate theory is used to describe the accumulation and clustering of radiation defects, while the phase-field approach describes the effect of radiation defects on phase stability and microstructure evolution. The Fe-Cu-Mn ternary alloy is taken as a model system. The free energies used in the phase-field model are from CALPHAD. Spatial dependent radiation damage from atomistic simulations is introduced into the simulation cell for a given radiation dose rate. The radiation effect on segregation and phase separation is taken into account through the defect concentration dependence of solute mobility. Using the model, the effect of temperature and radiation rates on Cu and Mn segregation and Cu-rich phase nucleation were systematically investigated. The segregation and nucleation mechanisms were analyzed. The simulations demonstrate that the nucleus of Cu precipitates has a core-shell composition profile, i.e. Cu-rich at the center and Mn-rich at the interface, in good agreement with theoretical calculations as well as experimental observations.

  3. Neutron diffraction study of quadruple perovskite SrCu{sub 3}Fe{sub 3}O{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Ikuya, E-mail: i-yamada@21c.osakafu-u.ac.jp [Nanoscience and Nanotechnology Research Center, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8570 (Japan); Murakami, Makoto; Mori, Shigeo [Department of Materials Science, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Irifune, Tetsuo [Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577 (Japan)

    2016-08-26

    The magnetic structure of the quadruple perovskite SrCu{sub 3}Fe{sub 4}O{sub 12} is studied by means of neutron powder diffraction. The magnetic diffraction peaks are observed at low temperatures below 200 K. The Rietveld refinement result suggests an antiferromagnetic alignment of Fe spin magnetic moments for SrCu{sub 3}Fe{sub 4}O{sub 12} at low temperature. The refined magnetic moment at 4 K is ∼3.5 µ{sub B}, which is larger than that of that of CeCu{sub 3}Fe{sub 4}O{sub 12} (2.3 µ{sub B}). The increase in the magnetic moment is attributed to the larger Fe{sup 3+}:Fe{sup 5+} ratio for SrCu{sub 3}Fe{sub 4}O{sub 12} (∼4:1) compared with that of CeCu{sub 3}Fe{sub 4}O{sub 12} (∼3:1).

  4. Study of Cu-doping effects on magnetic properties of Fe-doped ZnO ...

    Indian Academy of Sciences (India)

    Administrator

    Study of Cu-doping effects on magnetic properties of Fe-doped ZnO by first principle calculations. A EL AMIRI*, H LASSRI†, M ABID and E K HLIL††. Laboratoire de Physique Fondamentale et Appliquée (LPFA), Faculté des Sciences Ain Chock,. Université Hassan II, B.P. 5366 Mâarif, Casablanca, Morroco. †Laboratoire de ...

  5. Fe3O4@HKUST-1 and Pd/Fe3O4@ HKUST-1 as magnetically recyclable catalysts prepared via conversion from a Cu-based ceramic

    OpenAIRE

    Toyao, Takashi; Styles, Mark J.; Yago, Tokuichiro; Sadiq, Muhammad M.; Ricco, Raffaele; Suzuki, Kiyonori; Horiuchi, Yu; Takahashi, Masahide; Matsuoka, Masaya; Falcaro, Paolo

    2017-01-01

    Nanocomposites obtained by integrating iron oxide magnetic nanoparticles (Fe3O4) into a metal-organic framework (HKUST-1 or Cu-3(BTC)(2), BTC = 1,3,5-benzenetricarboxylate) are synthesized through conversion from a composite of a Cu-based ceramic material and Fe3O4. In situ small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) measurements reveal that the presence of Fe3O4 leads to the fast conversion and synthesis of HKUST-1 with small particle sizes. The prepared MOF co...

  6. Microwave-Assisted Synthesis of CuFe2O4 Nanoparticles and Starch-Based Magnetic Nanocomposites

    Directory of Open Access Journals (Sweden)

    Gh. Nabiyouni

    2013-06-01

    Full Text Available Magnetic CuFe2O4 nanoparticles were synthesized by a facile microwave-assisted reaction between Cu(NO32 and Fe(NO33. The magnetic nanoparticles were added to starch to make magnetic polymeric nanocomposite. The nanoparticles and nanocomposites were characterized using X-ray diffraction and scanning electron microscopy. The magnetic properties of the samples were investigated using an alternating gradient force magnetometer (AGFM. The copper ferrite nanoparticles exhibited ferromagnetic behavior at room temperature, with a saturation magnetization of 29emu/g and a coercivity of 136 Oe. The distribution of the CuFe2O4 nanoparticles into the polymeric matrixes decreases the coercivity (136 Oe to 66 Oe. The maximum coercivity of 82 Oe was found for 15% of CuFe2O4 distributed to the starch matrix.

  7. The Concentration of Zn, Fe, Mn, Cu and Se in Fiber Fractions of Legumes in Indonesia

    Directory of Open Access Journals (Sweden)

    Evitayani

    2010-05-01

    Full Text Available This study was carried out to evaluate concentration of micro minerals (Zn, Fe, Mn, Cu and Se of forages and their distribution in fiber fraction (neutral detergent fiber/NDF and acid detergent fiber/ADF in West Sumatra during dry and rainy seasons. Four species of common legume namely Leucaena leucocephala, Centrocema pubescens, Calopogonium mucunoides and Acacia mangium were collected at native pasture during rainy and dry seasons. The results showed that micro minerals concentration of forages and their distribution in fiber fraction varied among species and season. In general, concentration of micro minerals was slightly higher in rainy season compared to dry season either in legumes forages. Data on legume forages showed that 75% of legumes were deficient in Zn and Mn, 62.5 % deficient in Cu and 50 % deficient in Se. There was no species of legume deficient in Fe. Distribution of micro minerals in NDF and ADF were also significantly affected by species and season and depends on the kinds of element measured. Generally, micro minerals were associated in fiber fractions and it yield much higher during dry season compared to rainy season. Iron (Fe and selenium (Se in forages were the highest elements associated in NDF and ADF, while the lowest was found in Copper (Cu. (Animal Production 12(2: 105-110 (2010Keywords: Seasons, forages, micro mineral distribution, fiber fraction

  8. Pressure-induced polar phases in multiferroic delafossite CuFeO2

    Science.gov (United States)

    Terada, Noriki; Khalyavin, Dmitry D.; Manuel, Pascal; Osakabe, Toyotaka; Radaelli, Paolo G.; Kitazawa, Hideaki

    2014-06-01

    The pressure effect on the frustrated magnetic system CuFeO2 exhibiting multiferroic behavior has been studied by means of time-of-flight single crystal neutron diffraction combined with a hybrid-anvil-type pressure cell. The nonpolar collinear magnetic ground state (CM1 phase) with propagation vector k =(0,1/2,1/2) turns into a proper screw magnetic ordering with incommensurate modulation k =(0,q,1/2;q≃0.4) and a polar 21' magnetic point group (ICM2 phase), between 3 and 4 GPa. This spin structure is similar to the ferroelectric phase induced by magnetic field or chemical doping under ambient pressure. Above, 4 GPa, a magnetic phase (ICM3) appears, with an incommensurate propagation vector that is unique for the CuFeO2 system, k =(qa,qb,qc;qa≃0,qb≃0.34,qc≃0.43). This propagation vector at the general point results in triclinic magnetic symmetry which implies an admixture of both cycloidal and proper screw spin configurations. The ICM3 phase is stable in a narrow pressure range, and above 6 GPa, the spin-density collinear structure (ICM1 phase), similar to the first ordered state at ambient pressure, takes place. Comparing the degree of lattice distortions among the magnetic phases observed at ambient pressure, we discuss the origin of the pressure-induced magnetic phase transitions in CuFeO2.

  9. Raman spectroscopy and field emission characterization of delafossite CuFeO2

    Science.gov (United States)

    Pavunny, Shojan P.; Kumar, Ashok; Katiyar, R. S.

    2010-01-01

    Delafossite p-type CuFeO2 (CFO) semiconductors were synthesized by a modified solid state reaction technique and investigated by x-ray diffraction, x-ray photoemission spectroscopy (XPS), energy dispersive x-ray spectroscopy, and scanning electron microscopy, revealing the single-phase nature of CFO with 1:1 Cu/Fe atomic ratio. The valance states of CFO were examined by XPS and suggest Cu and Fe ions are in +1 and +3 valance states with high spin S=5/2. The "turn-on field" which is the macroscopic field needed to get an emission current of 9 nA, was calculated as 5.72 V/μm. Room temperature Raman spectra of CFO displayed two main Raman active modes at Eg˜351 cm-1 and Ag˜692 cm-1 in accord with other delafossite structures. Temperature dependent Raman spectra showed that both the modes shifted to lower frequency with significant decrease in intensity with increase in temperature. Frequency shift and linewidth of both phonon lines matched well with the theoretical damped harmonic oscillator model based on thermal expansion of the lattice and their anharmonicity coupling with other phonons.

  10. Enhanced Photocurrent of Transparent CuFeO2 Photocathodes by Self-Light-Harvesting Architecture.

    Science.gov (United States)

    Oh, Yunjung; Yang, Wooseok; Kim, Jimin; Jeong, Sunho; Moon, Jooho

    2017-04-26

    Efficient sunlight-driven water-splitting devices can be achieved by using an optically and energetically well-matched pair of photoelectrodes in a tandem configuration. The key for maximizing the photoelectrochemical efficiency is the use of a highly transparent front photoelectrode with a band gap below 2.0 eV. Herein, we propose two-dimensional (2D) photonic crystal (PC) structures consisting of a CuFeO2-decorated microsphere monolayer, which serve as self-light-harvesting architectures allowing for amplified light absorption and high transparency. The photocurrent densities are evaluated for three CuFeO2 2D PC-based photoelectrodes with microspheres of different sizes. The optical analysis confirmed the presence of a photonic stop band that generates slow light and at the same time amplifies the absorption of light. The 410 nm sized CuFeO2-decorated microsphere 2D PC photocathode shows an exceptionally high visible light transmittance of 76.4% and a relatively high photocurrent of 0.2 mA cm(-2) at 0.6 V vs a reversible hydrogen electrode. The effect of the microsphere size on the carrier collection efficiency was analyzed by in situ conductive atomic force microscopy observation under illumination. Our novel synthetic method to produce self-light-harvesting nanostructures provides a promising approach for the effective use of solar energy by highly transparent photocathodes.

  11. Relation of Zn, Fe, Cu and Mn between progenies of mate-tree and soil

    Directory of Open Access Journals (Sweden)

    Josiane Cava Guimarães

    2014-06-01

    Full Text Available The mate tea tree (Ilex Paraguariensis St. Hil. has considerable growth in acid a low fertility soils. The knowledge of soil and plant relation will contribute to genetic improvement programs, as highly capable progenies in nutrient acquisition may be selected. The objective of this study was to evaluate the interference of provenance and, or progenies, in relations established among the extractable contents of Zn, Fe, Cu and Mn, via Mehlich-1 (1:10; and EDTA (1%, with the corresponding contents in the mate tea tree leaves. In the experiment two provenances, Ivaí-PR and Barão de Cotegipe-RS, with five progenies each considered as treatments. The samples were distributed in four randomized blocks, totalizing 120 plant leaf samples, related to 120 soil samples of a Red Distrophic Latosol. The results were analyzed and fitted in regression equations. In Ivaí provenance Zn and Mn from the soil correlated with their contents in the leaves for progeny 04, for both extracts. For provenances 08 and 10, soil Mn via EDTA correlated with leaf Mn contents, while via Mehlich-1 only for progeny 10. In the provenance of Barão de Cotegipe, the correlations between soil and leaves for Zn, Fe and Cu occurred for the EDTA extract in the progenies 61, 65 and 69 respectively. For Mn and Cu, via Melich-1 the correlations occurred for progenies 53 and 69 respectively, and still for Cu, via EDTA, for progeny 53.

  12. Amorphous Fe72Cu1V4Si15B8 ribbon as magneto-impedance sensing element

    Directory of Open Access Journals (Sweden)

    Surla Radoslav

    2016-01-01

    Full Text Available Мagneto-impedance (MI effect in the Fe72Cu1V4Si15B8 amorphous ribbon obtained by melt spinning method has been studied. The aim of study was the characterisation of this ribbon in as-cast state in terms of its application as a MI sensor. The experiments on MI elements were performed in the frequency range from 30 kHz to 300 MHz and maximum external magnetic field up to 28.6 kA/m. Maximum observed MI-ratio (ΔZ = Z(0 - Z(Hmax, Hmax = 28.6 kA/m has amounted to ΔZ/Z(Hmax = 173% at a frequency of 20.46 MHz. The MI curve measured up to 20 MHz shows some shoulder indicating the growth of rotational contribution of magnetization that appears above the domain wall relaxation frequency. The MI profile at frequencies higher than 30 MHz, exhibits a clear peak positioned at transverse anisotropy field Hk, suggesting domination of rotation magnetization in transverse permeability. The linearity in the range up to 5 kA/m with sensitivity of about 11 %/kA/m was observed. [Projekat Ministarstva nauke Republike Srbije, br. OI 172057

  13. Fe-Si-B-P-C-Cu nanocrystalline soft magnetic powders with high Bs and low core loss

    OpenAIRE

    Takahashi, T.; Yoshida, K; Shimizu, Y; A. D. Setyawan; M. Bito; Abe, M.; Makino, A.

    2017-01-01

    The magnetic properties of Fe-Si-B-P-C-Cu nanocrystalline powders were investigated. Fe-Si-B-P-C-Cu powders with a mostly amorphous structure were prepared by an atomization method. The atomized powders were annealed in inert gas atmosphere for nanocrystallization. The Fe84.8Si0.5B9.4P3.5C1Cu0.8 nanocrystalline powder exhibits high Bs of 1.76T, which is appreciably higher than that of conventional Fe-based amorphous powders (1.3 - 1.5 T) and close to that of Fe3.5Si4.5Cr (1.86T) crystalline o...

  14. Probing structure-property relationships in perpendicularly magnetized Fe/Cu(001) using MXLD and XPD

    Energy Technology Data Exchange (ETDEWEB)

    Cummins, T.R.; Waddill, G.D. [Univ. of Missouri, Rolla, MO (United States); Goodman, K.W. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Magnetic X-ray Linear Dichroism (MXLD) in Photoelectron Spectroscopy and X-Ray Photoelectron Diffraction (XPD) of the Fe 3p core level have been used to probe the magnetic structure-property relationships of perpendicularly magnetized Fe/Cu(001), in an element-specific fashion. A strong MEXLD effect was observed in the high resolution photoelectron spectroscopy of the Fe 3p at {open_quotes}normal{close_quotes} emission and was used to follow the loss of perpendicular ferromagnetic ordering as the temperature was raised toward room temperature. In parallel with this, {open_quotes}Forward Focussing{close_quotes} in XPD was used as a direct measure of geometric structure in the overlayer. These results and the implications of their correlation will be discussed. Additionally, an investigation of the effect of Mn doping of the Fe/Cu(001) will be described. These measurements were performed at the Spectromicroscopy Facility (Beamline 7.0.1) of the Advanced Light Source.

  15. Facile preparation of magnetic mesoporous Fe{sub 3}O{sub 4}/C/Cu composites as high performance Fenton-like catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Li, Keyan; Zhao, Yongqin [State Key Laboratory of Fine Chemicals, PSU-DUT Joint Center for Energy Research, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); Janik, Michael J. [Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Song, Chunshan [State Key Laboratory of Fine Chemicals, PSU-DUT Joint Center for Energy Research, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); EMS Energy Institute, PSU-DUT Joint Center for Energy Research and Department of Energy & Mineral Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Guo, Xinwen, E-mail: guoxw@dlut.edu.cn [State Key Laboratory of Fine Chemicals, PSU-DUT Joint Center for Energy Research, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China)

    2017-02-28

    Highlights: • Fe-Cu composites with different compositions were prepared by calcining tartrates. • Magnetic mesoporous Fe{sub 3}O{sub 4}/C/Cu was obtained by calcining tartrate under N{sub 2}. • Fe{sub 3}O{sub 4}/C/Cu exhibits excellent photo-Fenton catalytic activity and reusability. • The activity is due to the synergistic and photo-reduction effects of Fe and Cu. - Abstract: Fe-Cu composites with different compositions and morphologies were synthesized by a hydrothermal method combined with precursor thermal transformation. γ-Fe{sub 2}O{sub 3}/CuO and α-Fe{sub 2}O{sub 3}/CuO were obtained by calcining the Fe and Cu tartrates under air atmosphere at 350 °C and 500 °C, respectively, while Fe{sub 3}O{sub 4}/C/Cu was obtained by calcining the tartrate precursor under N{sub 2} atmosphere at 500 °C. The Fe{sub 3}O{sub 4}/C/Cu composite possessed mesoporous structure and large surface area up to 133 m{sup 2} g{sup −1}. The Fenton catalytic performance of Fe{sub 3}O{sub 4}/C/Cu composite was closely related to the Fe/Cu molar ratio, and only proper amounts of Fe and Cu exhibited a synergistic enhancement in Fenton catalytic activity. Cu inclusion reduced Fe{sup 3+} to Fe{sup 2+}, which accelerated the Fe{sup 3+}/Fe{sup 2+} cycles and favored H{sub 2}O{sub 2} decomposition to produce more hydroxyl radicals for methylene blue (MB) oxidation. Due to the photo-reduction of Fe{sup 3+} and Cu{sup 2+}, the Fenton catalytic performance was greatly improved when amending with visible light irradiation in the Fe{sub 3}O{sub 4}/C/Cu-H{sub 2}O{sub 2} system, and MB (100 mg L{sup −1}) was nearly removed within 60 min. The Fe{sub 3}O{sub 4}/C/Cu composite showed good recyclability and could be conveniently separated by an applied magnetic field. Compared with conventional methods for mesoporous composite construction, the thermolysis method using mixed metal tartrates as precursors has the advantages of easy preparation and low cost. This strategy provides a facile

  16. The metal-insulator transition in Fe(1.01-x)Cu(x)Se.

    Science.gov (United States)

    Williams, A J; McQueen, T M; Ksenofontov, V; Felser, C; Cava, R J

    2009-07-29

    Iron selenide, Fe(1.01)Se, the layered parent compound of the recently discovered superconducting arsenide family, has previously been shown to be non-magnetic and superconducting with a critical temperature of 8 K. Here we show that copper can be substituted at the iron site in Fe(1.01)Se up to a solubility limit of 20-30%, after which a first-order transition to the three-dimensional CuFeSe(2) structure type is observed. As little as 1.5% copper is sufficient to suppress the superconductivity, and 4% drives the system through a metal-insulator transition. A local magnetic moment is introduced, which maximizes near 12% doping, where a spin-glass transition near 15 K is observed.

  17. Effect of SnO 2 coating on the magnetic properties of nanocrystalline CuFe 2O 4

    Science.gov (United States)

    Selvan, R. Kalai; Augustin, C. O.; Sanjeeviraja, C.; Prabhakaran, D.

    2006-03-01

    Nanocrystalline CuFe 2O 4 and CuFe 2O 4/ xSnO 2 nanocomposites ( x=0, 1, 5 wt%) have been successfully synthesized by one-pot reaction of urea-nitrate combustion method. The transmission electron microscope study reveals that the particle size of the as synthesized CuFe 2O 4 and CuFe 2O 4/5 wt%SnO 2 are 10 and 20 nm, respectively. The SnO 2 coating on the nanocrystalline CuFe 2O 4 was confirmed from HRTEM studies. The resultant products were sintered at 1100 °C and characterized by XRD and SQUID for compound formation and magnetic studies, respectively. The X-ray diffraction pattern shows the well-defined sharp peak that confirms the phase pure compound formation of tetragonal CuFe 2O 4. The zero field cooled (ZFC) and field cooled (FC) magnetization was performed using SQUID magnetometer from 2 to 350 K and the magnetic hysteresis measurement was carried out to study the magnetic properties of nanocomposites.

  18. Estudio cinético de las reacciones de recocido en aleaciones de Cu-Ni-Fe

    Directory of Open Access Journals (Sweden)

    Donoso, Eduardo

    2014-09-01

    Full Text Available The thermal aging of a Cu-45Ni-4Fe, Cu-34Ni-11Fe and Cu-33Ni-22Fe alloys tempered from 1173 K have been studied from Differential Scanning Calorimetry (DSC and microhardness measurements. The analysis of DSC curves, from room temperature to 950 K, shows the presence of one exothermic reaction associated to the formation of FeNi3 phase nucleating from a modulate structure, and one endothermic peak attributed to dissolution of this phase. Kinetic parameters were obtained using the usual Avrami-Erofeev equation, modified Kissinger method and integrated kinetic functions. Microhardness measurements confirmed the formation and dissolution of the FeNi3 phase.Mediante Calorimetría Diferencial de Barrido (DSC y medidas de microdureza Vickers se ha estudiado el comportamiento durante el recocido de las aleaciones Cu-45Ni-4Fe, Cu-34Ni-11Fe y Cu-33Ni-22Fe templadas desde 1173 K. El análisis de las curvas DSC, desde temperatura ambiente hasta los 950 K, muestran la presencia de una reacción exotérmica asociada a la formación de la fase FeNi3 que nuclea a partir de una estructura modulada, y una reacción endotérmica que correspondería a la disolución de esta fase. Los parámetros cinéticos se calcularon a partir de la ecuación usual de Avrami-Erofeev, Kissinger modificado y funciones cinéticas integradas. Medidas de microdureza Vickers corroboraron la formación y disolución de fase FeNi3.

  19. Antifungal activity of magnetically separable Fe3O4/ZnO/AgBr nanocomposites prepared by a facile microwave-assisted method

    Directory of Open Access Journals (Sweden)

    Abolghasem Hoseinzadeh

    2016-08-01

    Full Text Available In the present work, magnetically separable Fe3O4/ZnO/AgBr nanocomposites with different weight ratios of Fe3O4 to ZnO/AgBr were prepared by a facile microwave-assisted method. The resultant samples were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, energy dispersive analysis of X-rays (EDX, and vibrating sample magnetometery (VSM. Antifungal activity of the as-prepared samples was evaluated against Fusarium graminearum and Fusarium oxysporum as two phytopathogenic fungi. Among the nanocomposites, the sample with 1:8 weight ratio of Fe3O4 to ZnO/AgBr was selected as the best nanocomposite. This nanocomposite inactivates Fusarium graminearum and Fusarium oxysporum at 120 and 60 min, respectively. Moreover, it was observed that the microwave irradiation time has considerable influence on the antifungal activity and the sample prepared by irradiation for 10 min showed the best activity. Moreover, the nanocomposite without any thermal treatment displayed the superior activity.

  20. Fe-Si-B-P-C-Cu nanocrystalline soft magnetic powders with high Bs and low core loss

    Directory of Open Access Journals (Sweden)

    T. Takahashi

    2017-05-01

    Full Text Available The magnetic properties of Fe-Si-B-P-C-Cu nanocrystalline powders were investigated. Fe-Si-B-P-C-Cu powders with a mostly amorphous structure were prepared by an atomization method. The atomized powders were annealed in inert gas atmosphere for nanocrystallization. The Fe84.8Si0.5B9.4P3.5C1Cu0.8 nanocrystalline powder exhibits high Bs of 1.76T, which is appreciably higher than that of conventional Fe-based amorphous powders (1.3 - 1.5 T and close to that of Fe3.5Si4.5Cr (1.86T crystalline one. The magnetic loss of toroidal core made of the Fe84.8Si0.5B9.4P3.5C1Cu0.8 nanocrystalline powder is also the lowest compared to that of amorphous and crystalline counterparts. This result indicates that Fe-Si-B-P-C-Cu nanocrystalline powders could contribute in efficiency-improvement as well as miniaturization of soft-magnetic cores.

  1. Transition metal complexes with thiosemicarbazide-based ligands. Part 60. Reactions of copper(II) bromide with pyridoxal S-methylisothiosemicarbazone (PLITSC). Crystal structure of [Cu(PLITSC–H)H2O]Br·H2O

    National Research Council Canada - National Science Library

    Vukadin M Leovac; Ljiljana S Vojinović-Ješić; Sonja A Ivković; Marko V Rodić; Ljiljana S Jovanović; Berta Holló; Katalin Mészáros Szécsényi

    2014-01-01

    The synthesis and structural characterization of a square-planar copper(II) complex with pyridoxal S-methylisothiosemicarbazone (PLITSC) of the formula [Cu(PLITSC–H)H2O]Br·H2O (1) as the first Cu(II...

  2. Crystal structure and physical properties of conducting molecular antiferromagnets with a halogen-substituted donor: (EDO-TTFBr2)2FeX4 (X = Cl, Br).

    Science.gov (United States)

    Miyazaki, A; Yamazaki, H; Aimatsu, M; Enoki, T; Watanabe, R; Ogura, E; Kuwatani, Y; Iyoda, M

    2007-04-16

    The crystal structure and physical properties of radical ion salts (EDO-TTFBr2)2FeX4 (X = Cl, Br) based on halogen-substituted organic donor and magnetic anions are investigated, including the comparison with the isomorphous compounds (EDO-TTFBr2)2GaX4 with nonmagnetic anions. The crystal structure of these four salts consists of uniformly stacked donor molecules and tetrahedral counter anions, and the Br substituents of the donor molecules are connected to halide ligands of anions with remarkably short intermolecular atomic distances. These salts show metallic behavior around room temperature and undergo a spin-density-wave transition in the low-temperature range, as confirmed with the divergence of the electron spin resonance (ESR) line width. Although close anion-anion contacts are absent in these salts, the FeCl4 salt undergoes an antiferromagnetic transition at TN = 4.2 K, and the FeBr4 salt shows successive magnetic transitions at TN = 13.5 K and TC2 = 8.5 K with a helical spin structure as a candidate for the ground state of the d-electron spins. The magnetoresistance of the FeCl4 salt shows stepwise anomalies, which are explained qualitatively using a pi-d interaction-based frustrated spin system model composed of the donor pi-electron and the anion d-electron spins. Although on the ESR spectra of the FeX4 salts signals from the pi- and d-electron spins are separately observed, the line width of the pi-electron spins broadens under the temperature where the susceptibility deviates from the Curie-Weiss behavior, showing the presence of the pi-d interaction.

  3. Fabrication of magnetically recyclable Fe{sub 3}O{sub 4}@Cu nanocomposites with high catalytic performance for the reduction of organic dyes and 4-nitrophenol

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Mingyi, E-mail: mingyitjucu@163.com [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Zhang, Sai; Li, Xianxian; Pang, Xiaobo [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Qiu, Haixia [School of Science, Tianjin University, Tianjin 300072 (China)

    2014-12-15

    A facile and efficient approach to synthesize Fe{sub 3}O{sub 4}@Cu nanocomposites using L-Lysine as a linker was developed. The morphology, composition and crystallinity of the Fe{sub 3}O{sub 4}@Cu nanocomposites were characterized by Fourier Transform infrared spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and powder X-ray diffraction. In addition, the magnetic properties were determined with vibrating sample magnetometer. The surface of the Fe{sub 3}O{sub 4} contained many small Cu nanoparticles with sizes of about 3 nm. It was found that the Fe{sub 3}O{sub 4}@Cu nanocomposites could catalyze the degradation of organic dyes. The catalytic activities of the Fe{sub 3}O{sub 4}@Cu nanocomposites for the reduction of nitrophenol were also studied. The Fe{sub 3}O{sub 4}@Cu nanocomposites are more efficient catalysts compared with Cu nanoparticles and can easily be recovered from the reaction mixture with magnet. The cost effective and recyclable Fe{sub 3}O{sub 4}@Cu nanocomposites provide an exciting new material for environmental protection applications. - Highlights: • Cu nanoparticles as small as 3 nm are synthesized. • Low cost Fe{sub 3}O{sub 4}@Cu magnetical nanoparticles show catalytic activity for organic dyes and 4-nitrophenol. • The Fe{sub 3}O{sub 4}@Cu display high catalytic activity after 13 cycles.

  4. A facile approach to fabricate of photothermal functional Fe{sub 3}O{sub 4}@CuS microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Baolong; Shan, Yan, E-mail: shanyan@qust.edu.cn; Chen, Kezheng, E-mail: kchen@qust.edu.cn

    2017-06-01

    Photothermal functional Fe{sub 3}O{sub 4}@CuS microspheres have been prepared successfully by a simple chemical deposition method. The adsorption of cetyltrimethyl-ammonium bromide (CTAB) on the magnetic microspheres plays an important role in forming the structure of the composites. The present materials are characterized with XRD, TEM, SEM, FTIR, and UV-VIS-NIR spectrophotometer. The results show that Fe{sub 3}O{sub 4} microspheres are coated by CuS layer with thickness of 10 nm. The saturation magnetization value of Fe{sub 3}O{sub 4}@CuS core-shell microspheres is 27 emu/g at room temperature and the sample possesses excellent magnetic response in the presence of applied magnetic field. Moreover, these microspheres exhibit good dispersion, suitable size and significant photothermal conversion efficiency up to 20.7% at 808 nm laser irradiation. Fluctuation value of the highest temperature of Fe{sub 3}O{sub 4}@CuS dispersion over four times LASER ON/OFF indicates that photothermal stability of Fe{sub 3}O{sub 4}@CuS microspheres is good. - Highlights: • The Fe{sub 3}O{sub 4} microspheres have been coated with CuS and the thickness of CuS layer is about 10 nm. • The Fe{sub 3}O{sub 4}@CuS microspheres are ferromagnetism, and possess good photothermal conversion efficiency and photostability. • The materials have great potential application for photothermal therapy.

  5. The influence of cooling rate and Fe/Cr content on the evolution of Fe-rich compounds in a secondary Al-Si-Cu diecasting alloy

    Science.gov (United States)

    Fabrizi, A.; Timelli, G.

    2016-03-01

    This study investigates the morphological evolution of primary α-Al(Fe,Mn,Cr)Si phase in a secondary Al-Si-Cu alloy with respect to the initial Fe and Cr contents as well as to the cooling rate. The solidification experiments have been designed in order to cover a wide range of cooling rates, and the Fe and Cr contents have been varied over two levels. Metallographic and image analysis techniques have been used to quantitatively examine the microstructural changes occurring at different experimental conditions. The morphological evolution of the α-Fe phase has been also analysed by observing deep etched samples. By changing the cooling rate, α-Al15(Fe,Mn,Cr)3Si2 dodecahedron crystals, as well as Chinese- script, branched structures and dendrites form, while primary coarse β-Al5(Fe,Mn)Si needles appear in the alloy with the highest Fe content at low cooling rates.

  6. Interacting spin-1/2 tetrahedral system Cu2Te2O5X2 (X = Cl, Br)

    DEFF Research Database (Denmark)

    Jensen, Jens

    2009-01-01

    Magnetic ordering and excitations of Cu2Te2O5Cl2 are analyzed in terms of a tetramerized spin model for the tetrahedral Cu clusters of spin 1/2. The mean-field model is able to account for the main properties of the incommensurable magnetic structure observed by Zaharko et al. [Phys. Rev. B 73, 0...

  7. Synthesis and rate performance of Fe3O4-based Cu nanostructured electrodes for Li ion batteries

    Science.gov (United States)

    Duan, Huanan; Gnanaraj, Joe; Liang, Jianyu

    2011-05-01

    Fe3O4-based Cu nanostructured electrodes for Li ion batteries are fabricated by a two-step electrochemical process, and characterized with scanning electron microscopy, X-ray diffraction, and electrochemical experiments. It is found that the electrochemical performance is closely related to the Fe3O4 morphology. The nanostructured electrodes with 1 min Fe3O4 deposition exhibit a large specific discharge capacity, i.e. 1342.23 mAh g-1 in the first cycle and 1003.94 mAh g-1 in the 34th. After extended Fe3O4 electroplating, Fe3O4 particles will fill the spaces between the Cu nanorods and coalesce on the top of the Cu nanorod arrays, which is detrimental to achieve high specific reversible capacities and good rate capability. Moreover, the nanostructured electrodes demonstrate significantly enhanced cycling performance due to the introduction of Cu nanorod arrays as the current collector, especially as compared to the planar electrodes where Fe3O4 is electrodeposited directly onto planar Cu surfaces.

  8. Magnetic phase diagram of multiferroic delafossite CuFe{sub 1-y}Ga{sub y}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Terada, N; Kitazawa, H [National Institute for Materials Science, Tsukuba, Ibaraki, Japan 305-0047 (Japan); Nakajima, T; Mitsuda, S, E-mail: terada.noriki@nims.go.j [Department of Physics, Faculty of Science, Tokyo University of Science, Tokyo 162-8601 (Japan)

    2009-01-01

    We report magnetic susceptibility measurements on nonmagnetic impurity-doped multiferroic CuFe{sub 1-y}Ga{sub y}O{sub 2} with 0 <= y <= 0:08. The temperature versus Ga concentration magnetic phase diagram was obtained. Comparing the presently obtained phase diagram of CuFe{sub 1-y}Ga{sub y}O{sub 2} with that of CuFe{sub 1-x}Al{sub x}O{sub 2}, we find that the stability of 4SL ground state for substitution of nonmagnetic ions does not depend on the nonmagnetic ionic radius significantly. On the other hand, the FEIC phase in CuFe{sub 1-y}Ga{sub y}O{sub 2} exists in a wider region of 0:02 <= y <= 0:05 than CuFe{sub 1-x}Al{sub x}O{sub 2}. We thus find that the local lattice distortion caused by large difference in ionic radii between Al3{sup +} and Fe3{sup +} affects the stability of the FEIC phase for nonmagnetic ion substitution significantly.

  9. Efficiency of dislocations and cavities for gettering of Cu and Fe in silicon

    Science.gov (United States)

    Stritzker, B.; Petravic, M.; Wong-Leung, J.; Williams, J. S.

    2001-04-01

    Dislocations (of interstitial character) as well as cavities are known for their ability to getter impurities within Si. In order to determine the relative gettering strength we produced both dislocations and cavities at different depths within (1 0 0) Si. This was obtained by implantation and subsequent annealing of 3×10 16 (40 keV H)/cm 2 and 1×10 16 (140 keV Si)/cm 2 resulting in cavities and dislocations at depths of 400 nm and 200 nm, respectively. Fe or Cu was then implanted with a dose of 5×10 13 atoms/ cm2 and an energy of 35 keV. By selective implantation of different areas, all possible combinations of impurities, dislocations and cavities were obtained within one Si-sample. The results show, clearly, that Cu-impurities are gettered totally by cavities (or open-volume defects), even when dislocations are also present. In contrast, Fe-impurities, which are released from traps near the surface during annealing, are gettered by both interstitial-based dislocations and open-volume defects. Secondary ion mass spectrometry and transmission electron microscopy analyses reveal defect-Fe-impurity interactions at the different trap sites.

  10. Microstructure and Properties of W-Cu Composite/Fe-Based Powder Alloy Vacuum Brazed Joint with Different Filler Metals

    Science.gov (United States)

    Xia, C. Z.; Yang, J.; Xu, X. P.; Zou, J. S.

    2017-05-01

    W-Cu composite and Fe-based powder alloy were brazed with filler metals of Ag-Cu and Cu-Mn-Co alloys in a vacuum furnace. Both of filler metals can join W-Cu composite with Fe-based powder alloy directly in the experiment process. Microstructure, distribution of elements and fracture morphology were observed and analyzed using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) methods, and phase composition of bonding area was analyzed by X-ray diffraction (XRD). The obtained results indicated that the smooth faying surface and dense microstructure of brazed joint were formed and the primary microstructure of brazing seam were, respectively, Ag(Cu) solid solution and Cu(Mn) solid solution, which ensured forming the stable connection of brazed joint. The bending strength of Ag-based and Cu-based brazed joint can, respectively, reach to 317 and 704 MPa, where fracture showed a typical ductile fracture characteristic. The fracture of Cu-based brazed joint located at brazing seam area, and the fracture of Ag-based brazed joint occurred in Fe-based powder alloy side.

  11. Experimental investigation of inhomogeneities, nanoscopic phase separation, and magnetism in arc melted Fe-Cu metals with equal atomic ratio of the constituents

    KAUST Repository

    Hassnain Jaffari, G.

    2015-12-16

    Composition gradient and phase separation at the nanoscale have been investigated for arc-melted and solidified with equiatomic Fe-Cu. Diffraction studies revealed that Fe and Cu exhibited phase separation with no trace of any mixing. Microscopy studies revealed that immiscible Fe-Cu form dense bulk nanocomposite. The spatial distribution of Fe and Cu showed existence of two distinct regions, i.e., Fe-rich and Cu-rich regions. Fe-rich regions have Cu precipitates of various sizes and different shapes, with Fe forming meshes or channels greater than 100 nm in size. On the other hand, the matrix of Cu-rich regions formed strips with fine strands of nanosized Fe. Macromagnetic response of the system showed ferromagnetic behavior with a magnetic moment being equal to about 2.13 μB/Fe atom and a bulk like negligible value of coercivity over the temperature range of 5–300 K. Anisotropy constant has been calculated from various laws of approach to saturation, and its value is extracted to be equal to 1350 J/m3. Inhomogeneous strain within the Cu and Fe crystallites has been calculated for the (unannealed) sample solidified after arc-melting. Annealed sample also exhibited local inhomogeneity with removal of inhomogeneous strain and no appreciable change in magnetic character. However, for the annealed sample phase separated Fe exhibited homogenous strain.

  12. A study of copper precipitation in the thermally aged FeCu alloy using SANS

    Energy Technology Data Exchange (ETDEWEB)

    Park, D. G.; Kim, J. H.; Kwon, S. C.; Kim, W. W. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Lee, M. N.; Koo, Y. M. [Pohang University of Science and Technology, Pohang (Korea, Republic of)

    2005-07-01

    The continued operation or lifetime extension of a number of nuclear power plant around the world requires an understanding of the damage imparted to the reactor pressure vessel (RPV) steel by radiation. Irradiation embrittlement of nuclear reactor pressure vessel steels results from a high number of nanometer sized Cu rich precipitates (CRPs) and sub-nanometer defect-solute clusters. The copper precipitation leads to a distortion of the crystal lattice surrounding the copper precipitates and yields an internal micro-stress. In order to study the effect of copper precipitation on the steel embrittlement under neutron irradiation, the characteristics of nano size defects were investigated using small angle neutron scattering (SANS) in the thermal aged FeCu model alloys. The results on the precipitation composition, number density, size distribution and matrix composition obtained using a high resolution TEM and SANS are compared and contrasted.

  13. Oxidation of Refractory Benzothiazoles with PMS/CuFe2O4: Kinetics and Transformation Intermediates

    KAUST Repository

    Zhang, Tao

    2016-05-04

    Benzothiazole (BTH) and its derivatives, 2-(methylthio)bezothiazole (MTBT), 2-benzothiazolsulfonate (BTSA) and 2-hydroxybenzothiazole (OHBT), are refractory pollutants ubiquitously existing in urban runoff at relatively high concentrations. Here, we report their oxidation by CuFe2O4-activated peroxomonosulfate (PMS/CuFe2O4), focusing on kinetics and transformation intermediates. These benzothiazoles can be efficiently degraded by this oxidation process which is confirmed to generate mainly sulfate radicals (with negligible hydroxyl-radical formation) under slightly acidic to neutral pH conditions. The molar exposure ratio of sulfate radical to residual PMS (i.e. Rct) of this process is a constant which is related to reaction condition and can be easily determined. Reaction rate constants of these benzothiazoles towards sulfate radical are (3.3 ± 0.3) × 109, (1.4 ± 0.3) × 109, (1.5 ± 0.1) × 109 and (4.7 ± 0.5) × 109 M-1s-1, respectively (pH 7 and 20 oC). Based on Rct and these rate constants, their degradation in the presence of organic matter can be well predicted. A number of transformation products were detected and tentatively identified using triple-quadruple/linear ion trap MS/MS and high-resolution MS. It appears that sulfate radicals attack BTH, MTBT and BTSA on their benzo ring via electron transfer, generating multiple hydroxylated intermediates which are reactive towards common oxidants. For OHBT oxidation, it prefers to break down the thiazole ring. Due to competitions of the transformation intermediates, a minimum PMS/pollutant molar ratio of 10-20 is required for effective degradation. The flexible PMS/CuFe2O4 could be a useful process to remove the benzothiazoles from low DOC waters like urban runoff or polluted groundwater.

  14. Impedance investigation of the highly efficient polymer solar cells with composite CuBr2/MoO3 hole transport layer.

    Science.gov (United States)

    Li, Zhiqi; Guo, Wenbin; Liu, Chunyu; Zhang, Xinyuan; Li, Shujun; Guo, Jiaxin; Zhang, Liu

    2017-08-09

    Developing an air-stable, low-cost, non-toxic, and high-transparency charge buffer layer is a critical strategy to achieve the high photoelectric conversion efficiency of polymer photovoltaic cells. This paper reports the remarkable improvement of device performance by employing a combination of copper bromide (CuBr2) and molybdenum trioxide (MoO3) (CuBr2/MoO3) as the hole transport layer (HTL) of inverted-type polymer solar cells (PSCs). The bulk transport processes and resistive capacitance elements in the operating PTB7:PC71BM bulk heterojunction PSCs were characterized using impedance spectroscopy. The impedance response was modeled using two equivalent circuital models, which are the general transmission line circuit (GTLC) model and the electrochemical polarization model. The effective carrier lifetime, conductivity, and mobility for both devices were extracted from the models. The improved hole transport at the anode and the efficient electron transport blocking decreased interface recombination and contact resistance, resulting in improved power conversion efficiency (PCE) values ranging from 7.30% to 9.56%. These results suggest that quantitative interpretation and modeling of the impedance spectroscopy results provide an effective way to unravel the operating mechanism of photovoltaic devices.

  15. The Effect of Substitution of Fe By Co on Rapidly Quenched (FeCoMoCuB Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    Clara F. Conde

    2005-01-01

    Full Text Available (Fe1-xCox79Mo8Cu1B15 amorphous alloys ware prepared in the form of ribbons by rapid quenching for x=0. 0.25 and 0.5. The effect of variation of Co/Fe ratio is analyzed with respect to the formation of amorphous state and to transformation of the structure into nancrystalline phases formed after subsequent thermal treatment. Selected properties and atomic structure in as-quenched state are studied by TEM, AFM, XRD any by measurement of magnetoresistance characteristics. The influence of heat treatment on transport and magnetic properties is shown on temperature dependencies of electrical resistivity and magnetization. It was founf that while the increase of Co content leads to the increase of Curie temperature of as-quenched structure, transition to nanocrystalline state is not affected in a significant manner. The as-quenched state for alloy without Co was found to contain thin crystal-containing layer which, however, was observed, contary to general behavior, at the side of the ribbon exposed to higher quenching rates.

  16. Comparative TPR and TPD Studies of Cu and Ca Promotion on Fe-Zn- and Fe-Zn-Zr-Based Fischer-Tropsch Catalysts

    Directory of Open Access Journals (Sweden)

    James Olusola O.

    2015-03-01

    Full Text Available The present study demonstrates the effect of zirconium promotion on Fe-Zn-based catalysts to boost the active sites of Fischer-Tropsch (FT catalysts. The catalysts are also promoted by Cu and Ca and the active sites are examined using Temperature-Programmed Reduction (TPR with H2 and CO and Temperature-Programmed Desorption (TPD with NH3 and CO2. The results are presented as a comparative study between Fe-Zn- and Fe-Zn-Zr-based catalysts. The results show that addition of Zr to Fe-Zn catalysts increases the availability and dispersion of the precursor to the active sites and promotion with Cu and Ca independently and synergistically enhances reduction of Fe-Zn-Zr-based catalysts. The presence of Ca promotes carburisation, while Cu inhibits carburisation. The impact of the Ca and Cu on the surface acidity/basicity is governed by the nature of the interaction between the phases in the catalysts. The extent of reduction reflects the availability and dispersion of the precursor to the active phase, while the extent of carburisation will impact on the selectivity of the catalysts.

  17. Multiferroic phase of doped delafossite CuFeO2 identified using inelastic neutron scattering

    Science.gov (United States)

    Haraldsen, Jason T.; Ye, Feng; Fishman, Randy S.; Fernandez-Baca, Jamie A.; Yamaguchi, Yasuhiro; Kimura, Kenta; Kimura, Tsuyoshi

    2010-07-01

    We report inelastic neutron scattering measurements that provide a distinct dynamical “fingerprint” for the multiferroic ground state of 3.5% Ga-doped CuFeO2 . The complex ground state is stabilized by the displacement of the oxygen atoms, which contribute to the multiferroic coupling predicted in the “spin-driven” model. By comparing the observed and calculated spectrum of spin excitations, we conclude that the magnetic ground state is a distorted screw-type spin configuration with a distribution of turn angles.

  18. Synthesis and characterisation of delafossite CuFeO2 for solar energy applications

    OpenAIRE

    Forslund, Axel

    2016-01-01

    Delafossite CuFeO2 is an intrinsic p-type semiconductor with a band gap around 1.5 eV. Further, it is composed of relatively abundant, nontoxic elements, and therefor have potential to be an attractive material for solar energy harvesting.This work examines three routes to synthesise this material. The first includes a sol-gel deposition and then relies on solid state reaction above 650 degrees Celsius in inert gas atmosphere. In this work, no delafossite is obtained with this method.The seco...

  19. THERMAL STABILITY OF Al-Cu-Fe QUASICRYSTALS PREPARED BY SHS METHOD

    Directory of Open Access Journals (Sweden)

    Pavel Novák

    2013-04-01

    Full Text Available Quasicrystal-containing materials are usually prepared by rapid solidification of the melt (e.g. by melt spinning or mechanical alloying. In this work, the method using exothermic reactions between compressed metallic powders called SHS (Self-propagating High-temperature Synthesis was tested. The microstructure and phase composition of the product was described in dependence on cooling regime from the reaction temperature. Thermal stability of prepared Al-Cu-Fe quasicrystals was studied by annealing at the temperatures of 300 and 500 °C.

  20. Thermal stability of Al-Cu-Fe quasicrystals prepared by SHS method

    Directory of Open Access Journals (Sweden)

    Pavel Novak

    2013-02-01

    Full Text Available Quasicrystal-containing materials are usually prepared by rapid solidification of the melt (e.g. by melt spinning or mechanical alloying. In this work, the method using exothermic reactions between compressed metallic powders called SHS (Self-propagating High-temperature Synthesis was tested. The microstructure and phase composition of the product was described in dependence on cooling regime from the reaction temperature. Thermal stability of prepared Al-Cu-Fe quasicrystals was studied by annealing at the temperatures of 300 and 500 °C.

  1. Formation dynamics of FeN thin films on Cu(100)

    KAUST Repository

    Heryadi, Dodi

    2012-01-01

    To investigate the structural and magnetic properties of thin films of FeN we have performed ab initio molecular dynamics simulations of their formation on Cu(100) substrates. The iron nitride layers exhibit a p4gm(2 × 2) reconstruction and order ferromagnetically in agreement with experiment. We establish the dynamics and time scale of the film formation as a function of the film thickness. The process is split in two phases: formation of almost flat FeN layers and optimization of the distance to the substrate. Our calculated magnetic moments are 1.67 μ B, 2.14 μ B, and 2.21 μ B for one, two, and three monolayers of iron nitride. © 2011 Elsevier B.V. All rights reserved.

  2. Characterization of pillared clays containing Fe{sup 3+} and Cu

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Vidal, H.; Custodio-Garcia, E.; Morales-Hidalgo, J. [Division Academica de Ciencias Basicas, Universidad Juarez Autonoma de Tabasco, Km 1.5 Carretera Cunduacan-Jalpa, CP. 86690, Cunduacan, Tabasco (Mexico); Lopez-Alejandro, E.; Frias-Marquez, D.M. [Division Academica de Ingenieria y Arquitectura, Universidad Juarez Autonoma de Tabasco, Km 1.5 Carretera Cunduacan-Jalpa, CP. 86690, Cunduacan, Tabasco (Mexico)

    2006-04-14

    We report the synthesis of pillared clays from natural Mexican bentonites and pillared solutions as a support for Cu and Fe{sup 3+} catalyst. The study shows a favorable cationic exchange capacity on the clays. This is observed with a change of the specific areas: from 66m{sup 2}/g for the natural clay to 202m{sup 2}/g for the pillared clay. The molar relation of 4.91 for the Si/Al structure in the natural clay and 3.72 for the pillared clay shows the entrance of aluminum as pillaring ion. We were able to increase the microporosity on the catalytic material observed through a porous volume variation (0.1-0.8cm{sup 3}/g) at different Fe{sup 3+} concentrations. We obtained an increase on the specific area of more than 200% over the natural clay. (author)

  3. Induced ferromagnetism at BiFeO3/YBa2Cu3O7 interfaces.

    Science.gov (United States)

    Zhu, Jian-Xin; Wen, Xiao-Dong; Haraldsen, J T; He, Mi; Panagopoulos, C; Chia, Elbert E M

    2014-06-20

    Transition metal oxides (TMOs) exhibit many emergent phenomena ranging from high-temperature superconductivity and giant magnetoresistance to magnetism and ferroelectricity. In addition, when TMOs are interfaced with each other, new functionalities can arise, which are absent in individual components. Here, we report results from first-principles calculations on the magnetism at the BiFeO3/YBa2Cu3O7 interfaces. By comparing the total energy for various magnetic spin configurations inside BiFeO3, we are able to show that a metallic ferromagnetism is induced near the interface. We further develop an interface exchange-coupling model and place the extracted exchange coupling interaction strengths, from the first-principles calculations, into a resultant generic phase diagram. Our conclusion of interfacial ferromagnetism is confirmed by the presence of a hysteresis loop in field-dependent magnetization data. The emergence of interfacial ferromagnetism should have implications to electronic and transport properties.

  4. Adsorption performance of CuFe{sub 2}O{sub 4}/rGO nanocomposites towards organic dye

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Mingyi, E-mail: mingyitjucu@163.com [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Li, Xichuan [School of Science, Tianjin University, Tianjin 300072 (China); Gao, Chunjuan [State Ocean Adm, Inst Tianjin Seawater Desalinat & Multipurpose Ut, Tianjin 300192 (China); Li, Xianxian [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Qiu, Haixia, E-mail: haixiaqiuls@163.com [School of Science, Tianjin University, Tianjin 300072 (China)

    2017-01-01

    A facile and efficient approach was employed to synthesize CuFe{sub 2}O{sub 4}/rGO (reduced graphene oxide) nanocomposites. The morphology, crystal structure and properties of the prepared CuFe{sub 2}O{sub 4}/rGO nanocomposites were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, powder X-ray diffraction and thermo-gravimetric analysis. The CuFe{sub 2}O{sub 4}/rGO nanocomposites were applied as adsorbents to study their adsorption performance for Congo red. The adsorption capacity and recyclability, adsorption dynamics and adsorption models were investigated. The results show that the CuFe{sub 2}O{sub 4}/rGO nanocomposites are efficient and recyclable adsorbents. - Highlights: • CuFe{sub 2}O{sub 4}/rGO was synthesized by a facile hydrothermal route. • As an adsorbent it showed high adsorption capacity to CR. • It was magnetically removable and has high reusability.

  5. Magnetic properties of CuFe1-xCrxO2 nanoparticles surrounded by amorphous SiO2

    Science.gov (United States)

    Mori, K.; Hachisu, M.; Yamazaki, T.; Ichiyanagi, Y.

    2015-05-01

    CuFe1-xCrxO2 (0 ≤ x ≤ 1.0) nanoparticles surrounded by amorphous SiO2 with an average diameter of 30-50 nm were synthesized using a wet chemical method. The annealing temperatures were controlled to yield various sizes of single-phase CuFe1-xCrxO2 nanoparticles. CuFeO2 bulk crystal is known to have a multiferroic delafossite structure with two Néel temperatures of 11 and 14 K; however, the transition temperature shifted higher as the Cr-ion doping level increased. In addition, the lattice constants decreased in accordance with increased Cr-ion doping, which was confirmed by X-ray diffraction measurements. The magnetization curves showed weak ferromagnetic behavior and no coercivity was observed. Hence, frustration in the triangular lattice of the delafossite structure can be released by Cr-ion doping and higher magnetization can be expected. A fine structure analysis through X-ray absorption fine structure measurements was also conducted. It was found that the structure of the Cu ion is similar to that of Cu2O, and the c axis of the CuFe1-xCrxO2 should be shortened by the Cr-ion doping.

  6. Phase selection and nanocrystallization in Cu-free soft magnetic FeSiNbB amorphous alloy upon rapid annealing

    Energy Technology Data Exchange (ETDEWEB)

    Morsdorf, L.; Povstugar, I.; Raabe, D. [Department for Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf (Germany); Pradeep, K. G., E-mail: kg.prad@mpie.de, E-mail: kgprad@gmail.com [Department for Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf (Germany); Materials Chemistry, RWTH Aachen University, Kopernikusstrasse 10, 52074 Aachen (Germany); Herzer, G. [Vacuumschmelze GmbH & Co KG, Grüner Weg 37, D-63450 Hanau (Germany); Kovács, A.; Dunin-Borkowski, R. E. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute 5, Forschungszentrum Jülich, 52425 Jülich (Germany); Konygin, G. [Physical-Technical Institute UrB RAS, Kirov str. 132, 426008 Izhevsk (Russian Federation); Choi, P. [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141 (Korea, Republic of)

    2016-03-28

    Nucleation of soft magnetic Fe{sub 3}Si nanocrystals in Cu-free Fe{sub 74.5}Si{sub 15.5}Nb{sub 3}B{sub 7} alloy, upon rapid (10 s) and conventional (30 min) annealing, was investigated using x-ray diffraction, transmission electron microscopy, Mössbauer spectroscopy, and atom probe tomography. By employing rapid annealing, preferential nucleation of Fe{sub 3}Si nanocrystals was achieved, whereas otherwise there is simultaneous nucleation of both Fe{sub 3}Si and undesired Fe-B compound phases. Analysis revealed that the enhanced Nb diffusivity, achieved during rapid annealing, facilitates homogeneous nucleation of Fe{sub 3}Si nanocrystals while shifting the secondary Fe-B crystallization to higher temperatures resulting in pure soft magnetic nanocrystallization with very low coercivities of ∼10 A/m.

  7. Magnetochemistry of the tetrahaloferrate (III) ions. 7. Crystal structure and magnetic ordering in (pyridinium){sub 3}Fe{sub 2}Br{sub 9}

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, C.B.; Shaviv, R.; Carlin, R.L. [Univ. of Illinois, Chicago, IL (United States)] [and others

    1994-07-06

    A monoclinic crystal structure was found by X-ray diffraction for bis [pyridinium tetrabromferrate(III)]-pyridinium bromide. The double salt contains two slightly distorted [FeBr{sub 4}]{sup -} tetrahedra, three pyridinium rings, and an uncoordinated halide in each asymmetric unit, as is characteristic of the A{sub 3}Fe{sub 2}X{sub 9} series of compounds. Unit cell parameters, monoclinic space group P2{sub 1}, are a = 7.656(3) {angstrom}, b = 14.237(5) {angstrom}, c = 13.725(5) {angstrom}, {beta} = 93.42(3){degrees}, and V = 1493(1) {angstrom}{sup 3}, using Mo K{alpha} radiation {lambda} = 0.710 69 {angstrom}, {rho}{sub calc} = 2.38 g cm{sup -3}, and Z = 2. The tetrahedra are aligned with their 3-fold axes parallel to the crystallographic c axis. Bond lengths (Fe-Br) range from 2.271(9) {angstrom} to 2.379(9) {angstrom} for the two different slightly distorted tetrahedral units. Magnetic susceptibility studies show that the material orders three-dimensionally at 7.4 {+-} 0.2 K. The data are compared to a HTS expansion of 1/{sub {chi}} for the S = 5/2 three-dimensional Heisenberg model antiferromagnet for a sc lattice with g = 1.98 and J/k{sub B} = -0.43 K. The specific heat measurements indicate two odd-shaped {lambda} features, at 7.3 and 8 K.

  8. Magnetic Properties Studies on Thermal Aged Fe-Cu Alloys for the Simulation of Radiation Damage

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C. K.; Kishore, M.B.; Park, D. G. [KAERI, Daejeon (Korea, Republic of); Son, De Rac. [Hannam University, Daejeon (Korea, Republic of)

    2016-05-15

    We evaluated the changes in magnetic properties due to cold rolling and thermal ageing of a Fe-1%Cu model alloy in this study. Initially, the alloy was 10% cold rolled, and isothermally aged at 400 .deg. C for 1, 10, 100 and 1000 hr. The samples were prepared at various thermal aging conditions and all the conditions were interpreted. The hysteresis loops, Magnetic Barkhausen noise (BN). The change of magnetic properties can be interpreted in terms of the domain wall motion and dislocation dynamics associated with copper rich precipitates (CRPs).The results were interpreted in terms of ageing time dependence of the precipitates evolution such as the volume fraction and size distribution. In order to evaluate the radiation embrittlement of RPV steel, A Cold rolled Fe-Cu model Alloy was prepared, The prepared samples were thermally aged by annealing at 400 .deg. C for various times, the magnetic properties of the annealed samples were measured, The Barkhausen noise and BH Loop shows a considerable trend corresponding to the Ageing time. The magnetic properties were interpreted and correlated to the CRPs formed through annealing process.

  9. Heat treatment of the EN AC-AlSi9Cu3(Fe alloy

    Directory of Open Access Journals (Sweden)

    J. Pezda

    2010-04-01

    Full Text Available Silumins are widely used in automotive, aviation and shipbuilding industries; as having specific gravity nearly three times lower than specific gravity of cast iron the silumins can be characterized by high mechanical properties. Additionally, they feature good casting properties, good machinability and good thermal conductivity. i.e. properties as required for machinery components operating in high temperatures and at considerable loads. Mechanical properties of the silumins can be upgraded, implementing suitably selected heat treatment. In the paper is presented an effect of modification and heat treatment processes on mechanical properties of the EN AC-AlSi9Cu3(Fe alloy. Investigated alloy has undergone typical processes of modification and refining, and next heat treatment. Temperature range of the heat treatment operations was determined on base of curves from the ATD method. Obtained results concern registered melting and solidification curves from the ATD method and strength tests. On base of the performed tests one has determined range of the heat treatment parameters which would assure obtainment of the best possible mechanical properties of the EN AC-AlSi9Cu3(Fe alloy.

  10. Magnetoelasticity in ACr2O4 spinel oxides (A= Mn, Fe, Co, Ni, and Cu)

    Science.gov (United States)

    Kocsis, V.; Bordács, S.; Varjas, D.; Penc, K.; Abouelsayed, A.; Kuntscher, C. A.; Ohgushi, K.; Tokura, Y.; Kézsmárki, I.

    2013-02-01

    Dynamical properties of the lattice structure were studied by optical spectroscopy in ACr2O4 chromium spinel oxide magnetic semiconductors over a broad temperature region of T=10-335 K. The systematic change of the A-site ions (A= Mn, Fe, Co, Ni and Cu) showed that the occupancy of 3d orbitals on the A site has strong impact on the lattice dynamics. For compounds with orbital degeneracy (FeCr2O4, NiCr2O4, and CuCr2O4), clear splitting of infrared-active phonon modes and/or activation of silent vibrational modes have been observed upon the Jahn-Teller transition and at the onset of the subsequent long-range magnetic order. Although MnCr2O4 and CoCr2O4 show multiferroic and magnetoelectric character, no considerable magnetoelasticity was found in spinel compounds without orbital degeneracy as they closely preserve the high-temperature cubic spinel structure even in their magnetic ground state. Aside from lattice vibrations, intra-atomic 3d-3d transitions of the A2+ ions were also investigated to determine the crystal field and Racah parameters and the strength of the spin-orbit coupling.

  11. Scanning Tunneling Microscopy Studies of Surface Structures of Icosahedral Al-Cu-Fe Quasicrystals

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Tanhong [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    Three papers are included in this dissertation. The first paper: ''Structural aspects of the fivefold quasicrystalline Al-Cu-Fe surface from STM and dynamical LEED studies'', is in press with ''Surface Science''. The second paper: ''An STM study of the atomic structure of the icosahedral Al-Cu-Fe fivefold surface'' is submitted to ''Physical Review B, Rapid Communication''. The third paper: ''Pseudomorphic starfish: arrangement of extrinsic metal atoms on a quasicrystalline substrate'' is submitted to ''Nature''. Following the third paper are general conclusions and appendices that document the published paper ''Structural aspects of the three-fold surface of icosahedral Al-Pd-Mn'' (appearing in volume 461, issue 1-3 of ''Surface Science'' on page L521-L527, 2000), the design as well as the specifications of the aluminum evaporator used in the aluminum deposition study in this dissertation, an extended discussion of the aluminum deposition on the quasicrystalline surface, and the STM database.

  12. Carbon dioxide adsorption studies on delafossite CuFeO2 hydrothermally synthesized

    Science.gov (United States)

    Sarabia, M. A.; Rojas, S. D.; López-Cabaña, Z.; Villalba, R.; González, G.; Cabrera, A. L.

    2016-11-01

    Delafossite CuFeO2 oxide was synthesized by a hydrothermal technique using Cu2O and FeOOH as precursors with the addition of fused NaOH as mineralizer. The amount of rhombohedral and hexagonal delafossite phase formed depends on the synthesis time lapses between 2 and 5 days and on the NaOH concentration. The compounds obtained were analyzed with Raman Spectroscopy, X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) in order to obtain their morphological and structural properties. Optical behavior was studied by UV-vis Spectroscopy and gas adsorption measured with a Quartz-Crystal Microbalance (QCM). Our results show that this type of hydrothermal synthesis is capable of recreating the delafossite-type structure of copper-iron oxide and produces a high yield of material with the right stoichiometry. The highest uptake of carbon dioxide is observed on the sample with the highest ratio between rhombohedral and hexagonal delafossite phase.

  13. Liquid-liquid phase separation of freely falling undercooled ternary Fe-Cu-Sn alloy

    Science.gov (United States)

    Wang, W. L.; Wu, Y. H.; Li, L. H.; Zhai, W.; Zhang, X. M.; Wei, B.

    2015-11-01

    The active modulation and control of the liquid phase separation for high-temperature metallic systems are still challenging the development of advanced immiscible alloys. Here we present an attempt to manipulate the dynamic process of liquid-liquid phase separation for ternary Fe47.5Cu47.5Sn5 alloy. It was firstly dispersed into numerous droplets with 66 ~ 810 μm diameters and then highly undercooled and rapidly solidified under the containerless microgravity condition inside drop tube. 3-D phase field simulation was performed to explore the kinetic evolution of liquid phase separation. Through regulating the combined effects of undercooling level, phase separation time and Marangoni migration, three types of separation patterns were yielded: monotectic cell, core shell and dispersive structures. The two-layer core-shell morphology proved to be the most stable separation configuration owing to its lowest chemical potential. Whereas the monotectic cell and dispersive microstructures were both thermodynamically metastable transition states because of their highly active energy. The Sn solute partition profiles of Fe-rich core and Cu-rich shell in core-shell structures varied only slightly with cooling rate.

  14. Liquid-liquid phase separation of freely falling undercooled ternary Fe-Cu-Sn alloy

    Science.gov (United States)

    Wang, W .L.; Wu, Y. H.; Li, L. H.; Zhai, W.; Zhang, X. M.; Wei, B.

    2015-01-01

    The active modulation and control of the liquid phase separation for high-temperature metallic systems are still challenging the development of advanced immiscible alloys. Here we present an attempt to manipulate the dynamic process of liquid-liquid phase separation for ternary Fe47.5Cu47.5Sn5 alloy. It was firstly dispersed into numerous droplets with 66 ~ 810 μm diameters and then highly undercooled and rapidly solidified under the containerless microgravity condition inside drop tube. 3-D phase field simulation was performed to explore the kinetic evolution of liquid phase separation. Through regulating the combined effects of undercooling level, phase separation time and Marangoni migration, three types of separation patterns were yielded: monotectic cell, core shell and dispersive structures. The two-layer core-shell morphology proved to be the most stable separation configuration owing to its lowest chemical potential. Whereas the monotectic cell and dispersive microstructures were both thermodynamically metastable transition states because of their highly active energy. The Sn solute partition profiles of Fe-rich core and Cu-rich shell in core-shell structures varied only slightly with cooling rate. PMID:26552711

  15. Multiferroic phase of doped delafossite CuFeO2 identified using inelastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Haraldsen, Jason T [ORNL; Ye, Feng [ORNL; Fishman, Randy Scott [ORNL; Fernandez-Baca, Jaime A [ORNL; Yamaguchi, Y. [Osaka University; Kimura, K. [Osaka University; Kimura, T. [Osaka University

    2010-01-01

    Multiferroic materials allow the electric polarization to be controlled by switching the direction of magnetic ordering and consequently offer prospects for many new technological applications [1 4]. Because multiferroic behavior has been found in materials that exhibit complex (non-collinear and incommensurate) magnetic order, it is essential to know the spin arrangement of the ground states in these materials [4 9]. In many cases, elastic neutron scattering measurements alone are not sufficient to distinguish among several potential complex magnetic states. We report inelastic neutron scattering (INS) measurements that provide a distinct dynamical fingerprint for the multiferroic ground state of 3.5% Ga-doped CuFeO2. The complex ground state is stabilized by the displacement of the oxygen atoms [10], which are also responsible for the multiferroic coupling predicted by Arima [8]. By comparing the observed and calculated spectrum of spin excitations, we conclude that the magnetic ground state is a distorted screwtype spin configuration. The exchange interactions that stabilize this structure are consistent with those obtained from inelastic measurements [11, 12] on undoped CuFeO2.

  16. Ion-beam-induced magnetic transformation of CO-stabilized fcc Fe films on Cu(100)

    Science.gov (United States)

    Shah Zaman, Sameena; Oßmer, Hinnerk; Jonner, Jakub; Novotný, Zbyněk; Buchsbaum, Andreas; Schmid, Michael; Varga, Peter

    2010-12-01

    We have grown 22-ML-thick Fe films on a Cu(100) single crystal. The films were stabilized in the face-centered-cubic (fcc) γ phase by adsorption of carbon monoxide during growth, preventing the transformation to the body-centered-cubic (bcc) α phase. A structural transformation of these films from fcc to bcc can be induced by Ar+ ion irradiation. Scanning-tunneling microscopy images show the nucleation of bcc crystallites, which grow with increasing Ar+ ion dose and eventually result in complete transformation of the film to bcc. Surface magneto-optic Kerr effect measurements confirm the transformation of the Fe film from paramagnetic (fcc) to ferromagnetic (bcc) with an in-plane easy axis. The transformation can also be observed by low-energy electron diffraction. We find only very few nucleation sites of the bcc phase and argue that nucleation of the bcc phase happens under special circumstances during resolidification of the molten iron in the thermal spike after ion impact. Intermixing with the Cu substrate impedes the transformation. We also demonstrate the transformation of films coated with Au to protect them from oxidation at ambient conditions.

  17. Unraveling the Effects of Process Control Agents on Mechanical Alloying of Nanostructured Cu-Fe Alloy

    Directory of Open Access Journals (Sweden)

    Mina Rabiee

    2016-06-01

    Full Text Available Nanostructured Cu-20Fe alloy was synthesized by mechanical alloying process and the effects of process control agents (PCA on the phase formation, crystallite refinement and morphology of powder particles were studied. The dissolution of Fe into Cu matrix and the morphology of powder particles were analyzed by X-ray diffraction (XRD technique and scanning electron microscopy (SEM, respectively. The mean crystallite size was approximated by the method developed by Williamson and Hall. It was found that in the absence of PCA (Toluene in the present work, the iron peaks vanish after 5 h of mechanical alloying process and the mean crystallite size of the matrix decreases to 35 nm and large agglomerated particles are formed during milling. In this regard, it was found that the addition of PCA decreases the rate of crystallite refinement and formation of solid solution but does not affect the final mean crystallite size. It was also found that the addition of PCA during milling decreases the powder particle size considerably and by preventing agglomeration can lead to a finer powder particle size compared with the initial unmilled powders. It was also revealed that the effect of PCA on particle size is much greater than the effect of milling time.

  18. DETERMINATION OF Cu, Fe, Mn, Zn AND FREE FATTY ACIDS IN PEQUI OIL

    Directory of Open Access Journals (Sweden)

    Aparecida M. S. Mimura

    2016-06-01

    Full Text Available Pequi (Caryocar brasiliense Camb., a typical fruit of the Brazilian Cerrado, is an important source of micronutrients and fatty acids. In this work, a new approach for the acid digestion (using H2SO4, HNO3 and H2O2 of pequi oil samples and the determination of Cu, Fe, Zn and Mn by flame atomic absorption spectrometry (F AAS was employed. Capillary zone electrophoresis (CZE was used for free fatty acid (FFA determination after simple and fast extraction with heated ethanol. Good results regarding precision (RSD < 10%, in most cases, sensitivity and adequate LOD and LOQ values were obtained. The accuracy was evaluated using spike tests and the recoveries were from 97 to 107%. The analytes were investigated in four different pequi oil samples. Fe was the trace element with the highest concentration (from 1.99 to 10.3 mg/100 g, followed by Zn, Mn and Cu (1.15 to 3.19, 0.42 to 0.91 and 0.31 to 0.56 mg/100 g, respectively. The main FFA found were oleic acid and palmitic acid (1.61 to 10.7 and 0.82 to 2.69 g/100 g, respectively, while linoleic acid (0.50 g/100 g was detected in only one sample. The pequi oil chemical composition showed good characteristics to be used as a food additive, in cosmetic formulations and for traditional medicine.

  19. Structure, I-V characteristics and optical studies of delafossite CuFeO2 and CuFe0.96Ti0.03V0.01O2 prepared under high vacuum

    Science.gov (United States)

    Barot, Nishant; Mehta, Prashant K.; Shah, Devang D.; Panchal, C. J.

    2017-05-01

    Most opted methods for the preparation of CuFeO2 involve chemical route or solid state synthesis in the presence of inert gases like Argon and Nitrogen for the purpose of maintaining Cu in 1+ state. Here CuFeO2 (CFO) and doped CuFe0.96Ti0.03V0.01O2 (CFTO) samples are prepared under newly developed simple synthesis process involving high vacuum sealed annealing. Delafossite phase is confirmed by means of XRD measurements and its Rietveld refinement. The room temperature I-V measurements performed with different top contacts on the pallets show that CFO samples having `Ag' and `In' contacts shows better semiconducting properties compared to `Cu' and `Al' contacts owing to Schottky effect. On the other hand CFTO show good semiconducting nature only with `Ag' contacts. Bulk samples of CFO exhibiting better semiconducting nature compared to CFTO is mainly due to electron doping (substitution of Ti4+ at the Fe3+ site) induced enhancement in recombination in a system having predominantly holes as carries. Effect of Ti doping in CFO is reported perhaps for the first time.

  20. Structural and magnetic properties of epitaxial delafossite CuFeO{sub 2} thin films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Toyanath; Senty, Tess R.; Trappen, Robbyn; Zhou, Jinling; Borisov, Pavel; Holcomb, Mikel B.; Bristow, Alan D.; Lederman, David [Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315 (United States); Chen, Song; Song, Xueyan [Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, West Virginia 26506-6070 (United States); Ferrari, Piero; Cabrera, Alejandro L. [Pontificia Universidad Catolica, Instituto de Física, Santiago (Chile)

    2015-01-07

    Growth of pure phase delafossite CuFeO{sub 2} thin films on Al{sub 2}O{sub 3} (00.1) substrates by pulsed laser deposition was systematically investigated as a function of growth temperature and oxygen pressure. X-ray diffraction, transmission electron microscopy, Raman scattering, and x-ray absorption spectroscopy confirmed the existence of the delafossite phase. Infrared reflectivity spectra determined a band edge at 1.15 eV, in agreement with the bulk delafossite data. Magnetization measurements on CuFeO{sub 2} films demonstrated a phase transition at T{sub C} ≈ 15 ± 1 K, which agrees with the first antiferromagnetic transition at 14 K in the bulk CuFeO{sub 2}. Low temperature magnetic phase is best described by commensurate, weak ferromagnetic spin ordering along the c-axis.

  1. High temperature EPR study of the M3Fe4V6O24 (M = Cu, Zn, Mg and Mn

    Directory of Open Access Journals (Sweden)

    Guskos Niko

    2016-09-01

    Full Text Available Electron paramagnetic resonance (EPR spectra of M3Fe4V6O24 (M = Cu, Zn, Mg and Mn compounds in high temperature range (293 K to 493 K have been investigated. The role of magnetic (Cu, Mn and non-magnetic (Zn, Mg ions in M3Fe4V6O24 structure in formation of magnetic resonance spectra was studied. Temperature dependence of EPR parameters: resonance field, linewidth and integrated intensity were examined. Similarities and differences in temperature behavior of these parameters has been discussed in terms of different relaxation mechanisms and magnetic interactions in the spin systems. An important role of additional magnetic ions (M = Mn or Cu in the M3Fe4V6O24 structure has been identified and its consequences considered.

  2. Preparation of Cu-Fe-Al-O nanosheets and their catalytic application in methanol steam reforming for hydrogen production

    Science.gov (United States)

    Wang, Leilei; Zhang, Fan; Miao, Dinghao; Zhang, Lei; Ren, Tiezhen; Hui, Xidong; He, Zhanbing

    2017-03-01

    Candidates of precious metal catalysts, prepared in a facile and environmental way and showing high catalytic performances at low temperatures, are always highly desired by industry. In this work, large-scale Cu-Fe-Al-O nanosheets were synthesized by facile dealloying of Al-Cu-Fe alloys in NaOH solution. The composition, microscopic morphology, and crystal structure were respectively investigated using wavelength-dispersive x-ray spectroscopy with an electron probe microanalyzer, scanning electron microscopy, x-ray diffraction, and transmission electron microscopy. Furthermore, we found that the 2D Cu-Fe-Al-O nanosheets gave excellent catalytic performances in hydrogen production by methanol steam reforming at relatively low temperatures, e.g. 513 K.

  3. Comparative investigation of the coupled-tetrahedra quantum spin systems Cu{sub 2}Te{sub 2}O{sub 5}X{sub 2}, X = Cl, Br and Cu{sub 4}Te{sub 5}O{sub 12}Cl{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Valenti, R. [Institut fuer Theoretische Physik, Universitaet Frankfurt, Max-von-Laue-Strasse 1, 60438 Frankfurt (Germany)], E-mail: valenti@itp.uni-frankfurt.de; Saha-Dasgupta, T. [S.N. Bose National Centre for Basic Sciences, JD Block, Sector 3, Salt Lake City, Kolkata 700 098 (India); Jeschke, H.O. [Institut fuer Theoretische Physik, Universitaet Frankfurt, Max-von-Laue-Strasse 1, 60438 Frankfurt (Germany); Rahaman, B. [S.N. Bose National Centre for Basic Sciences, JD Block, Sector 3, Salt Lake City, Kolkata 700 098 (India); Rosner, H. [MPI-CPS, Noethnitzer Strasse 40, 01187 Dresden (Germany); Lemmens, P. [IPCM, TU Braunschweig, Mendelssohnstrasse 3, 38106 Braunschweig (Germany); Takagi, R.; Johnsson, M. [Department of Inorganic Chemistry, Stockholm University, S-10691 Stockholm (Sweden)

    2007-09-01

    We present a comparative study of the coupled-tetrahedra quantum spin systems Cu{sub 2}Te{sub 2}O{sub 5}X{sub 2}, X = Cl, Br (Cu-2252(X)) and the newly synthesized Cu{sub 4}Te{sub 5}O{sub 12}Cl{sub 4} (Cu-45124(Cl)) based on ab initio density functional theory calculations. The magnetic behavior of Cu-45124(Cl) with a phase transition to an ordered state at a lower critical temperature T{sub c} = 13.6 K than in Cu-2252(Cl) (T{sub c} = 18.2 K) can be well understood in terms of the modified interaction paths. We identify the relevant structural changes between the two systems and discuss the hypothetical behavior of the not yet synthesized Cu-45124(Br) with an ab initio relaxed structure using Car-Parrinello molecular dynamics.

  4. Tectono-metallogenetic evolution of the Fe-Cu deposit of Dominga, northern Chile

    Science.gov (United States)

    Veloso, E.; Cembrano, J.; Arancibia, G.; Heuser, G.; Neira, S.; Siña, A.; Garrido, I.; Vermeesch, P.; Selby, D.

    2017-04-01

    The Dominga district in northern Chile (2082 Mt at 23.3 % Fe, 0.07 % Cu) shows a spatial and genetic affinity among distinctive structural elements and Fe-Cu-rich paragenetic mineral assemblages. Deep seated, NE-to-E striking structural elements form a right-lateral duplex-like structural system (early structural system, ESS) that cuts a regionally extensive alteration (stage I) zone. The EES system served as a locus and as path for the emplacement of biotite-magnetite alteration/mineralization (stage IIa) as veins and Fe-bearing layers following altered volcano sedimentary strata. NW-striking actinolite-magnetite hydrothermal breccias, coeval with and part of the ESS, include apatite (stage IIb) crystallized at 127 ± 15 Ma (U-Pb, 2σ). The ESS was also the locus of subsequent alteration/mineralization represented by K-feldspar, epidote, and albite (stage IIIa) and Fe-Cu-rich (vermiculite-anhydrite-chalcopyrite, stage IIIb) mineral associations. Shallowly developed, NNE-striking, left-lateral structural elements defining the El Tofo Structural System (ETSS)—probably part of the Atacama Fault System—clearly crosscut the ESS. Minerals associated with alteration/mineralization stage IIIb also occur as veins and as part of hydrothermal breccias of the ETSS, marking the transition from the ESS to ETSS. Molybdenite associated with alteration/mineralization stage IIIb yielded a Re-Os age of 127.1 ± 0.7 Ma (2σ). Both the ESS and ETSS were cut by left-lateral, NW- to E-striking shallowly developed structural elements (Intermediate Structural System, ISS) on which a hematite-calcite assemblage (stage IV) occurs mostly as infill material of veins and fault veins. The ISS is cut by N-striking, left-lateral, and shallowly developed structural elements (Late Structural System, LSS) showing no evidence of alteration/mineralization. Estimated strain and stress fields indicate an overall NW-trending shortening/compression and NE-trending stretching/tension strike-slip regime

  5. Correlation between K, Mn, Fe, Cu and Zn in natural honeys from Eucalyptus sources

    Directory of Open Access Journals (Sweden)

    Silvânia V. M. Mattos

    1998-01-01

    Full Text Available Thirty-five natural honey samples from three apicultural regions of the state of Minas Gerais, Brazil, were collected from honeybee hives under various climatic conditions over a two-year period. The beehives were located in the districts of Bom Jesus do Amparo, Barão de Cocais and São Gonçalo do Rio Abaixo, all within a 100 km radius of Belo Horizonte, Minas Gerais, Brazil. The pollinic spectrum, color and ash, moisture, K, Fe, Mn, Cu and Zn contents were determined. Elemental analysis were done by flame atomic absorption spectrometry. Accuracy and precision were verified by recovery tests and relative standard deviation, respectively. The mean mineral contents encountered were K = 1130; Mn = 3.88; Fe = 2.79; Zn = 2.34 and Cu = 0.54 µ g/g. During the dry season, several species of Eucalyptus pollen grains predominated, with Vernonia pollen grains present in lower abundance. In the rainy season, there was an inversion of dominance. Statistical treatment of results, separated according to comb and season, showed statistically equivalent means, although some good correlation indices (p = 0.05 were obtained, e.g. between percent Eucalyptus pollen grains and Mn content (0.450, between Fe and Zn (0.698 and between K and Mn (0.738.Foram coletadas 35 amostras de mel natural em diferentes condições climáticas, por um período de dois anos. Os apiários se localizavam nos distritos de Bom Jesus do Amparo, Barão de Cocais e São Gonçalo do Rio Abaixo, a cerca de 100 km de Belo Horizonte, a capital do Estado de Minas Gerais, Brasil. As amostras foram analisadas quanto aos teores de K, Fe, Mn, Cu, Zn, espectro polínico, cor, cinzas e umidade. As médias encontradas foram: K = 1130; Mn = 3,88; Fe = 2,79; Zn = 2,34 e Cu = 0,54 µ g/g. No período de seca houve predomínio de grãos de pólen de origem de espécies de Eucalyptus e, em menor extensão de Vernonia. No período chuvoso, houve uma inversão dessa proporção. O tratamento estat

  6. Study of structural and magnetic properties of (Co–Cu)Fe{sub 2}O{sub 4}/PANI composites

    Energy Technology Data Exchange (ETDEWEB)

    Hashim, Mohd., E-mail: md.hashim09@gmail.com [Department of Applied Physics, Aligarh Muslim University, Aligarh 202 002 (India); Alimuddin [Department of Applied Physics, Aligarh Muslim University, Aligarh 202 002 (India); Shirsath, Sagar E. [Spin Device Technology Centre, Department of Information Engineering, Shinshu University, Nagano 380-8553 (Japan); Meena, S.S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kotnala, R.K. [National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110 012 (India); Kumar, Shalendra [Department of Physics, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Bhatt, Pramod [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Jotania, R.B. [Department of Physics, School of Science, Gujarat University, Ahmedabad 380 009 (India); Kumar, Ravi [Centre for Material Science Engineering, National Institute of Technology, Hamirpur 171 005, HP (India)

    2013-08-15

    The nanocomposites of the polyaniline and Co{sub 1−x}Cu{sub x}Fe{sub 2}O{sub 4} (PANI/CoCuFe) were prepared by in-situ oxidative polymerization of aniline. Prepared nanocomposites samples were characterized by using various experimental techniques like X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), field emission scanning electron microscope (FE-SEM), vibrating sample magnetometer (VSM), Mössbauer spectroscopy and ultraviolet–visible spectrophotometry (UV–VIS). The elemental analysis as obtained from the energy dispersive X-ray spectroscopy (EDAX) measurement is in close agreement with the expected composition from the stoichiometry of the reactant solutions. XRD result confirms that all the samples have the single phase cubic spinel structure. Unit cell parameter ‘a’ is found to decrease with the increase in copper ion substitution. The crystallite size was investigated by using the Debye–Scherer formula and it was found in the range of ∼28–37 nm. FE-SEM confirmed the homogeneous and well defined surface morphology of the synthesized samples. FT-IR study showed the main absorption bands corresponding to the spinel structure those arose due to the tetrahedral and octahedral stretching vibrations. Cation distribution was estimated using XRD data. Hysteresis measurements revealed that the saturation magnetization decreased with increase in Cu{sup 2+} substitution. Magnetic environment of {sup 57}Fe in Cu-doped cobalt ferrite was investigated by using Mössbauer spectroscopy. Mössbauer study evidenced the ferrimagnetic behavior of the synthesized samples. - Highlights: • Crystallite size decreases with increasing Cu{sup 2+} substitution. • The prepared samples show the formation of single phase cubic spinel structure. • Cation distribution shows that Cu and Co ions shows strong preference toward octahedral B site. • Magnetization decreases with increasing Cu{sup 2+} substitution. • Mössbauer study shows

  7. Crystal structure, Hirshfeld surface, physicochemical, thermal and DFT studies of (N1E, N2E)-N1,N2-bis((5-bromothiophen-2-yl)methylene)ethane-1,2-diamine N2S2 ligand and its [CuBr(N2S2)]Br complex

    Science.gov (United States)

    Warad, Ismail; Al-Demeri, Yasmin; Al-Nuri, Mohammed; Shahwan, Said; Abdoh, Muneer; Naveen, Shivalingegowda; Lokanath, Neartur Krishnappagowda; Mubarak, Mohammad S.; Ben Hadda, Taibi; Mabkhot, Yahia N.

    2017-08-01

    A new tetradentate N2S2 Schiff base ligand derived from 5-bromothiophene-2-carbaldehyde and its [CuBr(N2S2)]Br complex were synthesized in good yield. FT-IR was investigated to monitor the condensation reaction during the ligand synthesis process. The ligand, N2S2, and its complex, [CuBr(N2S2)]Br, complex have been characterized with the aid of several spectroscopic techniques such as UV-vis., MS, FT-IR, EA, EDS, NMR (for N2S2), as well as by thermal (TG/DTG) analysis. In addition, cyclic voltammetry has been employed to examine the redox behavior of [CuBr(N2S2)]Br complex in N,N'-dimethylformamide (DMF) containing 0.10 M tetra-n-butylammonium perchlorate (TBAP). The anti-conformation EE isomer of the ligand (N2S2) was confirmed by means of X-ray crystallography; ligand crystallizes in to the monoclinic P21/c space group. N2S2 ligand was subjected to DFT-theoretical calculations and results are consistent with the experimental chemical analysis.

  8. Comparative study of the doping effects in NdNiO{sub 3} by transition metals (Fe, Co, Cu)

    Energy Technology Data Exchange (ETDEWEB)

    Blasco, J. [ICMA, CSIC - Universidad de Zaragoza, 50009, Zaragoza (Spain); Garcia, J. [ICMA, CSIC - Universidad de Zaragoza, 50009, Zaragoza (Spain)

    1995-02-09

    Nickel has been partially replaced by other transition metals (Fe, Co, Cu) in the NdNiO{sub 3} perovskite. Magnetic and electrical measurements have been performed between 4.2 and 300 K in heating and cooling runs. The undoped NdNiO{sub 3} sample shows a metal-insulator transition (MI) at 205 K with a large thermal hysteresis. The substitution of Ni by Cu leads to metallic behaviour in the whole temperature range with an increase in the Pauli paramagnetism while the replacement of Ni by Fe or Co leads to semiconducting samples. ((orig.)).

  9. Fabrication of Fe3O4@CuO core-shell from MOF based materials and its antibacterial activity

    Science.gov (United States)

    Rajabi, S. K.; Sohrabnezhad, Sh.; Ghafourian, S.

    2016-12-01

    Magnetic Fe3O4@CuO nanocomposite with a core/shell structure was successfully synthesized via direct calcinations of magnetic Fe3O4@HKUST-1 in air atmosphere. The morphology, structure, magnetic and porous properties of the as-synthesized nano composites were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and vibration sample magnetometer (VSM). The results showed that the nanocomposite material included a Fe3O4 core and a CuO shell. The Fe3O4@CuO core-shell can be separated easily from the medium by a small magnet. The antibacterial activity of Fe3O4-CuO core-shell was investigated against gram-positive and gram-negative bacteria. A new mechanism was proposed for inactivation of bacteria over the prepared sample. It was demonstrated that the core-shell exhibit recyclable antibacterial activity, acting as an ideal long-acting antibacterial agent.

  10. Insulator-metal transitions induced by electric field and photoirradiation in organic Mott insulator deuterated κ-(BEDT-TTF)2Cu[N(CN)2]Br.

    Science.gov (United States)

    Sabeth, Farzana; Iimori, Toshifumi; Ohta, Nobuhiro

    2012-04-25

    The Mott insulator-metal transition induced by an external stimulus such as electric field, pressure, chemical doping, or photoirradiation has received considerable attention because of the potential use in new optoelectronic functional devices. Here we report an abrupt Mott insulator-metal transition observed as a current jump in a molecular-based Mott insulator, namely, deuterated κ-(BEDT-TTF)(2)Cu[N(CN)(2)]Br, where BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene, upon application of a pulsed voltage of certain magnitude (threshold voltage). Furthermore, the threshold voltage needed for the transition is shown to be reduced by photoirradiation. Thus, the Mott insulator-metal transition can be controlled by a combination of an external electric field and photoirradiation.

  11. Luttinger liquid physics in the spin ladder material CuBr{sub 4}(C{sub 5}H{sub 12}N){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Klanjsek, M. [Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Laboratoire National des Champs Magnetiques Intenses, CNRS, BP 166, 38042 Grenoble (France); Mayaffre, H. [Laboratoire de Spectrometrie Physique, Universite J. Fourier and UMR5588 CNRS, 38402 Saint Martin d' Heres (France); Berthier, C.; Horvatic, M. [Laboratoire National des Champs Magnetiques Intenses, CNRS, BP 166, 38042 Grenoble (France); Chiari, B.; Piovesana, O. [Dipartimento di Chimica, Universita di Perugia, I-06100 Perugia (Italy); Bouillot, P.; Giamarchi, T. [DPMC-MaNEP, University of Geneva, CH-1211 Geneva (Switzerland); Kollath, C. [Centre de Physique Theorique, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex (France); Orignac, E. [LPENSL CNRS UMR 5672, 69364 Lyon Cedex 07 (France); Citro, R. [Dipartimento di Fisica ' ' E. R. Caianiello' ' , Unita CNISM di Salerno, Universita degli Studi di Salerno, I-84081 Baronissi (Sa) (Italy)

    2010-03-15

    We present a {sup 14}N nuclear magnetic resonance study of a single crystal of CuBr{sub 4}(C{sub 5}H{sub 12}N){sub 2} consisting of weakly coupled spin-1/2 Heisenberg antiferromagnetic ladders. When placed in a magnetic field, such a ladder is theoretically predicted to exhibit a quantum critical Luttinger liquid (LL) behaviour in the gapless phase, i.e. between the two critical fields. Treating ladders as LLs and interaction between them as a perturbation, we are indeed able to fully account for (i) the spin dynamics accessed by measuring the spin-lattice relaxation rate T{sub 1}{sup -} {sup 1}, and for (ii) the phase transition to a 3D ordered phase occurring below 110 mK due to the weak interladder coupling. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  12. Teores de Fe, Mn, Zn, Cu, Ni E Co em solos de referência de Pernambuco Concentrations of Fe, Mn, Zn, Cu, Ni and Co in benchmark soils of Pernambuco, Brazil

    Directory of Open Access Journals (Sweden)

    Caroline Miranda Biondi

    2011-06-01

    Full Text Available Metais pesados formam um grupo de elementos com particularidades relevantes e de ocorrência natural no ambiente, como elementos acessórios na constituição de rochas. Esses elementos, apesar de associados à toxidez, exigem tratamento diferenciado em relação aos xenobióticos, uma vez que diversos metais possuem essencialidade (Fe, Mn, Cu, Zn e Ni e benefício (Co comprovados para as plantas. Nesse contexto, o objetivo deste trabalho foi determinar os teores naturais dos metais Fe, Mn, Zn, Ni, Cu e Co nos solos de referência de Pernambuco. Foram coletadas amostras de solo nas três regiões fisiográficas (Zona da Mata, Agreste e Sertão, dos dois primeiros horizontes dos 35 solos de referência do Estado de Pernambuco. A digestão das amostras baseou-se no método 3051A (USEPA, 1998, e a determinação foi efetuada em ICP-OES. Correlações significativas foram estabelecidas entre os metais e entre estes e a fração argila do solo, em ambos os horizontes, indicando a associação comum da maioria dos metais com solos mais argilosos. A maioria dos solos apresentou teores de Fe, Mn, Zn, Cu, Ni e Co menores que os de solos de outras regiões do País, com litologia mais máfica, o que corrobora o fato de que os teores desses elementos são mais diretamente relacionados aos minerais Fe-magnesianos. Os resultados indicam baixo potencial dos solos de Pernambuco em liberar Cu, Co e Ni para plantas, enquanto deficiências de Zn, Fe e Mn são menos prováveis. Os teores naturais de Fe, Mn, Zn, Cu, Ni e Co determinados podem ser utilizados como base para definição dos Valores de Referência de Qualidade para os solos de Pernambuco, de acordo com o preconizado pela legislação nacional.Heavy metals are a group of elements with specific features and natural occurrence in the environment, representing an accessory in the formation of rocks. These elements, although associated with toxicity, must be treated different from xenobiotics, since many

  13. Giant interfacial perpendicular magnetic anisotropy in Fe/CuIn 1 -xGaxSe2 beyond Fe/MgO

    Science.gov (United States)

    Masuda, Keisuke; Kasai, Shinya; Miura, Yoshio; Hono, Kazuhiro

    2017-11-01

    We study interfacial magnetocrystalline anisotropies in various Fe/semiconductor heterostructures by means of first-principles calculations. We find that many of those systems show perpendicular magnetic anisotropy (PMA) with a positive value of the interfacial anisotropy constant Ki. In particular, the Fe/CuInSe 2 interface has a large Ki of ˜2.3 mJ /m2 , which is about 1.6 times larger than that of Fe/MgO known as a typical system with relatively large PMA. We also find that the values of Ki in almost all the systems studied in this work follow the well-known Bruno's relation, which indicates that minority-spin states around the Fermi level provide dominant contributions to the interfacial magnetocrystalline anisotropies. Detailed analyses of the local density of states and wave-vector-resolved anisotropy energy clarify that the large Ki in Fe/CuInSe 2 is attributed to the preferable 3 d -orbital configurations around the Fermi level in the minority-spin states of the interfacial Fe atoms. Moreover, we have shown that the locations of interfacial Se atoms are the key for such orbital configurations of the interfacial Fe atoms.

  14. Thermo-Exfoliated Graphite Containing CuO/Cu2(OH3NO3:(Co2+/Fe3+ Composites: Preparation, Characterization and Catalytic Performance in CO Conversion

    Directory of Open Access Journals (Sweden)

    Vladyslav V. Lisnyak

    2010-01-01

    Full Text Available Thermo-exfoliated graphite (TEG/CuO/Cu2(OH3NO3:(Co2+/Fe3+ composites were prepared using a wet impregnation method and subsequent thermal treatment. The physicochemical characterization of the composites was carried out by powder X-ray diffraction (PXRD, scanning electron microscopy (SEM and Ar temperature-desorption techniques. The catalytic efficiency toward CO conversion to CO2 was examined under atmospheric pressure. Characterization of species adsorbed over the composites taken after the activity tests were performed by means of temperature programmed desorption massspectrometry (TPD MS. (TEG/CuO/Cu2(OH3NO3:(Co2+/Fe3+ composites show superior performance results if lower temperatures and extra treatment with H2SO4 or HNO3 are used at the preparation stages. The catalytic properties enhancements can be related to the Cu2(OH3NO3 phase providing reaction centers for the CO conversion. It has been found that prevalence of low-temperature states of desorbed CO2 over high-temperature ones in the TPD MS spectra is characteristic of the most active composite catalysts.

  15. Synthesis, identification and thermal decomposition of double sulfites like Cu2SO3·MSO3·2H2O (M=Cu, Fe, Mn or Cd)

    OpenAIRE

    L.A. Silva; MATOS, J.R.; Andrade, Jailson Bittencourt de

    2000-01-01

    Texto completo: acesso restrito. p.17–27 Double sulfites with empirical formula Cu2SO3·MSO3·2H2O (where M is Cu, Fe, Mn, or Cd) were obtained by saturation with sulfur dioxide gas of an aqueous mixture of MII sulfate and copper sulfate at room temperature. The salts obtained were identified by infrared spectra, X-ray powder diffraction and elemental analysis. The compounds studied are isostructural with the CuII replacement by MnII, FeII, and CdII in Chevreul’s salt (Cu2SO3·CuSO3·2H2O). Th...

  16. Synthesis and thermostructural studies of a CuFe(1-x)Cr(x)O(2) delafossite solid solution with 0

    Science.gov (United States)

    Lalanne, M; Barnabé, A; Mathieu, F; Tailhades, Ph

    2009-07-06

    In this work, different CuFe(1-x)Cr(x)O(2) compositions with 0 CuFe(1-x)Cr(x)O(2) solid solution was studied by thermogravimetric analysis and high-temperature X-ray diffraction experiments under an air atmosphere up to 1000 degrees C. For x = 0, CuFeO(2) is oxidized into the spinel (CuFe(2)O(4)) and copper monoxide (CuO) phases, whereas for x = 1, CuCrO(2) is thermally stable. For all of the intermediate compositions (0 < x < 1), complex oxidation, reduction, and phase transitions between delafossite and spinel have been observed. chromium tends to stabilize the stoichiometric delafossite phase, while iron favors the delafossite-to-spinel phase transition.

  17. Site selective Cu2+ substitution in single crystal Fe3O4 biocompatible nanospheres by solvothermal reflux method

    Science.gov (United States)

    Manohar, A.; Krishnamoorthi, C.

    2017-09-01

    Transition metal cations distribution among tetrahedral and octahedral sites in Fe3O4 has profound influence on it properties. The cations distribution among these sites were influenced by crystal field stabilization energy (CFSE) of a substituent ion. It was reported that Cu2+ substitutes both Fe3+ in tetrahedral and Fe2+ in octahedral sites of magnetite though it has high CFSE for octahedral sites. Thus it promotes mixed (normal & inverse) spinel structure and hence the properties deviate from the prediction. Here we show that selective octahedral site substitution of Fe2+ by Cu2+ in single crystal Fe3O4 nanoparticles was possible by solvothermal reflux method at moderate temperatures (≈300 °C). It was attributed to reduced energy barrier for crystallization and high diffusion coefficient of the metal cations at moderate temperature in low viscous organic solvents mixture, at ambient pressure, compared to coprecipitation and solid state reaction protocols. In addition, effective removal of exothermic crystal lattice energy, released during nucleation and growth process, by natural gas bubbles formed in the reflux organic solvent mixture. This promotes effective diffusion of cations during the growth process and easy octahedral occupation by Cu2+ in Fe1-xCuxFe2O4 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 & 0.6) single crystal nanospheres. The octahedral substitution was confirmed by reduction of crystal lattice parameter as well as ferromagnetic strength of octahedral sublattice with enhanced Cu2+ concentration. In addition, morphology, lattice vibrational frequency and electron excitation spectra of the nanospheres were studied. The Langevin function fit analysis reveals that superparamagnetic domain diameter were slightly less than the particle diameter obtained from TEM micrograph.

  18. Modification of The Electronic and The Adsorption Properties of Epitaxial Delafossite CuFeO2 thin films by The Substitution of Fe by Ga

    Science.gov (United States)

    Rojas, S.; Wheatley, R.; Joshi, T.; Lederman, D.; Cabrera, A. L.

    We studied the chemisorption properties of CuFeO2 and CuFe1-xGaxO2 delafossite thin film samples with respect to H2O and CO2 using thermal programmed desorption. Adsorption of CO2 and H2O was observed on both surfaces by X-Ray photoelectron spectroscopy. Substituting Fe by Ga in CuFeO2 leads to reduced amount of adsorbed H2O with respect to CO2. Additionally, NIR-Vis Transmittance and Reflectance spectroscopies were used to show changes in sample surface optical absorption properties in response to CO2/H2O exposure using a pressure range 0-90 kPa. This work was supported by FONDECyT 1130372 and Proyecto Anillo ACT1409 at PUC and supported in part by the WV Higher Education Policy Commission (Grant HEPC.dsr.12.29) and by FAME sponsored by MARCO and DARPA (contract # 2013-MA-2382).

  19. Change in magnetic properties of a cold rolled and thermally aged Fe-Cu alloy

    Science.gov (United States)

    Park, D. G.; Ryu, K. S.; Kobayashi, S.; Takahashi, S.; Cheong, Y. M.

    2010-05-01

    The variation in magnetic properties of a Fe-1%Cu model alloy due to a cold rolling and a thermal aging has been evaluated to simulate the radiation damage of reactor pressure vessel of nuclear power plant. The thermal aging was conducted at 500 °C with different aging times in series. The hysteresis loops, magnetic Barkhausen noise (BN) and Vickers microhardness were measured for prestrained, strained, and thermal aged samples. The coercivity increased by a plastic strain and decreased by thermal aging, The BN decreased in the prestrained and strained samples but large changes were observed in the strained sample. These results were interpreted in terms of the domain wall motion signified by a change in the mean free path associated with microinternal stress and copper rich precipitates.

  20. Removal of lead from the industrial and synthetic Cu-Pb-Fe alloy with argon barbotage

    Directory of Open Access Journals (Sweden)

    B. Oleksiak

    2012-01-01

    Full Text Available Results of research on removal of lead from synthetic and industrial Cu-Pb-Fe alloy with argon barbotage are presented. For examinations was taken a synthetic alloy and industrial alloy coming “Glogow II” Copperworks. As basic research equipment was used a pipe resistance furnace enabling heating of samples up to 1 473 K. Examinations were made in 2 test series. The 1 series was performed on the synthetic alloy, while in 2 series was used an industrial alloy. All series were conducted at 1 473 K and with gas fl ow 5,55•10-6, 6,94•10-6, 8,33•10-6, 9,72•10-6 m3•s-1.

  1. Current induced magnetization switching in Co/Cu/Ni-Fe nanopillar with orange peel coupling

    Science.gov (United States)

    Aravinthan, D.; Sabareesan, P.; Daniel, M.

    2015-07-01

    The impact of orange peel coupling on spin current induced magnetization switching in a Co/Cu/Ni-Fe nanopillar device is investigated by solving the switching dynamics of magnetization of the free layer governed by the Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation. The value of the critical current required to initiate the magnetization switching is calculated analytically by solving the LLGS equation and verified the same through numerical analysis. Results of numerical simulation of the LLGS equation using Runge-Kutta fourth order procedure shows that the presence of orange peel coupling between the spacer and the ferromagnetic layers reduces the switching time of the nanopillar device from 67 ps to 48 ps for an applied current density of 4 × 1012Am-2. Also, the presence of orange peel coupling reduces the critical current required to initiate switching, and in this case, from 1.65 × 1012Am-2 to 1.39 × 1012Am-2.

  2. Regulatory Effects of Cu, Zn, and Ca on Fe Absorption: The Intricate Play between Nutrient Transporters

    Directory of Open Access Journals (Sweden)

    Nathalie Scheers

    2013-03-01

    Full Text Available Iron is an essential nutrient for almost every living organism because it is required in a number of biological processes that serve to maintain life. In humans, recycling of senescent erythrocytes provides most of the daily requirement of iron. In addition, we need to absorb another 1–2 mg Fe from the diet each day to compensate for losses due to epithelial sloughing, perspiration, and bleeding. Iron absorption in the intestine is mainly regulated on the enterocyte level by effectors in the diet and systemic regulators accessing the enterocyte through the basal lamina. Recently, a complex meshwork of interactions between several trace metals and regulatory proteins was revealed. This review focuses on advances in our understanding of Cu, Zn, and Ca in the regulation of iron absorption. Ascorbate as an important player is also considered.

  3. Sintered Fe-Ni-Cu-Sn-C Alloys Made of Ball-Milled Powders

    Directory of Open Access Journals (Sweden)

    Romański A.

    2014-10-01

    Full Text Available The main objective of this paper was to perform sinterability studies of ball-milled Fe-12%Ni-6.4%Cu-1.6%Sn-0.6%C powders. A mixture of precisely weighed amounts of elemental iron, nickel and graphite, and pre-alloyed 80/20 bronze powders was ball-milled for 8, 30 and 120 hours. After cold-pressing at 400 MPa the specimens were sintered at 900oC for 30 minutes in a reducing atmosphere and subsequently tested for density and hardness as well as subjected to structural studies using scanning electron microscopy (SEM and X-ray diffraction (XRD analysis.

  4. Five-coordinate complexes [FeX(depe)(2)]BPh(4), X = Cl, Br: electronic structure and spin-forbidden reaction with N(2).

    Science.gov (United States)

    Franke, Oliver; Wiesler, Beatrix E; Lehnert, Nicolai; Näther, Christian; Ksenofontov, Vadim; Neuhausen, Jörg; Tuczek, Felix

    2002-07-01

    The bonding of N(2) to the five-coordinate complexes [FeX(depe)(2)](+), X = Cl (1a) and Br (1b), has been investigated with the help of X-ray crystallography, spectroscopy, and quantum-chemical calculations. Complexes 1a and 1b are found to have an XP(4) coordination that is intermediate between square-pyramidal and trigonal-bipyramidal. Mössbauer and optical absorption spectroscopy coupled with angular overlap model (AOM) calculations reveal that 1a and 1b have (3)B(1) ground states deriving from a (xz)(1)(z(2))(1) configuration. The zero-field splitting for this state is found to be 30-35 cm(-1). In contrast, the analogous dinitrogen complexes [FeX(N(2))(depe)(2)](+), X = Cl (2a) and Br (2b), characterized earlier are low-spin (S = 0; Wiesler, B. E.; Lehnert, N.; Tuczek, F.; Neuhausen, J.; Tremel, W. Angew. Chem, Int. Ed. 1998, 37, 815-817). N(2) bonding and release in these systems are thus spin-forbidden. It is shown by density functional theory (DFT) calculations of the chloro complex that the crossing from the singlet state (ground state of 2a) to the triplet state (ground state of 1a) along the Fe-N coordinate occurs at r(C) = 2.4 A. Importantly, this intersystem crossing lowers the enthalpy calculated for N(2) release by 10-18 kcal/mol. The free reaction enthalpy Delta G degrees for this process is calculated to be 4.7 kcal/mol, which explains the thermal instability of N(2) complex 2a with respect to the loss of N(2). The differences in reactivity of analogous trans hydrido systems are discussed.

  5. Iron atoms redistribution in oxide films of Zr-Fe, Zr-Fe-Cu alloys during corrosion in autoclave at 350°C

    Science.gov (United States)

    Filippov, V.; Bateev, A.

    2016-04-01

    The data on changes of iron atoms state in the oxide films of binary Zr-1.24 mas.%Fe and ternary Zr-1.39 mas.%Fe-0.60 mas.%Cu zirconium alloys are obtained. Alloys are subjected to corrosion tests under autoclave conditions at 350°C temperature in a steam-water environment under pressure p = 16.8 MPa. In initial specimens of the alloys the iron atoms are in the form of intermetallic compounds. In oxide films the decomposition of intermetallic compounds and formation of new compounds occurs with structural phase distortion. In the oxide films metallic the metallic iron particles α-Fe, iron oxide in the form of hematite α-Fe2O3, solid solutions of iron ions in ZrO2 are formed. The phase composition of the oxide films depends on the alloy composition and changes during the growth process of the oxide film.

  6. High-field recovery of the undistorted triangular lattice in the frustrated metamagnet CuFeO2

    NARCIS (Netherlands)

    Lummen, T. T. A.; Strohm, C.; Rakoto, H.; Nugroho, A. A.; van Loosdrecht, P. H. M.

    Pulsed-field magnetization experiments extend the typical metamagnetic staircase of CuFeO2 up to 58 T to reveal an additional first-order phase transition at high field for both the parallel and perpendicular field configuration. Virtually complete isotropic behavior is retrieved only above this

  7. Influence of the SmCo{sub 5} hard magnetic phase on the magnetoresistive properties of Cu-Fe ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Larde, R [Groupe de Physique des Materiaux UMR CNRS 6634, Universite de Rouen, Avenue de l' universite BP 12, 76801 St Etienne du Rouvray cedex (France); Le Breton, J M [Groupe de Physique des Materiaux UMR CNRS 6634, Universite de Rouen, Avenue de l' universite BP 12, 76801 St Etienne du Rouvray cedex (France); Richomme, F [Groupe de Physique des Materiaux UMR CNRS 6634, Universite de Rouen, Avenue de l' universite BP 12, 76801 St Etienne du Rouvray cedex (France); Teillet, J [Groupe de Physique des Materiaux UMR CNRS 6634, Universite de Rouen, Avenue de l' universite BP 12, 76801 St Etienne du Rouvray cedex (France); Hauet, A [Groupe de Physique des Materiaux UMR CNRS 6634, Universite de Rouen, Avenue de l' universite BP 12, 76801 St Etienne du Rouvray cedex (France); Maignan, A [Laboratoire CRISMAT-UMR 6508, ISMRA, 6 boulevard du Marechal Juin, F-14050 CAEN cedex (France); Crisan, O [National Institute for Materials Physics, PO Box MG-7, 76900 Bucharest (Romania)

    2004-10-20

    The SmCo{sub 5} hard magnetic phase was added to magnetoresistive granular Cu-Fe alloys in order to investigate the influence of the presence of a hard magnetic phase on the magnetoresistive properties of a granular alloy that contains a soft magnetic phase. Cu{sub 80}(Sm{sub 0.17}Co{sub 0.83}){sub x}Fe{sub 20-x} ribbons, with x = 20,15,10,5, obtained by melt spinning, were investigated. The ribbons are composed of magnetic Fe, SmCo{sub 5}, and Co precipitates embedded in a Cu matrix. In the as-quenched state, the magnetic interactions between magnetic precipitates lead to the formation of magnetic coherent regions and the magnetoresistance effect is only observed at high field (>1 T). After annealing, the strength of interactions decreases and a magnetoresistance effect is observed at low field (<1 T). The largest magnetoresistance effect (16%) is observed at 5 K for the Cu{sub 80}(Sm{sub 0.17}Co{sub 0.83}){sub 10}Fe{sub 10} alloy annealed at 450 deg. C.

  8. Study of Fe2O3, CuO, ZnO catalyzed efficient Hantzsch reaction under different conditions

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Shushizadeh

    2015-05-01

    Full Text Available 1,4-dihydropyridine derivatives one-pot synthesis under different condition was described. CuO nanoparticle as a catalyst in microwave irradiation (100w gives product with excellent yields (≥87% and short reaction time. No significant difference was observed between the obtained yield by using ZnO and Fe2O3.

  9. Simple Molecules Adsorption Studies on Highly Epitaxial -Pure Phase- Delafossite CuFeO2 Thin Films

    Science.gov (United States)

    Cabrera, Alejandro; Ferrari, Piero; Joshi, Toyanath; Borisov, Pavel; Lederman, David

    2014-03-01

    Carbon dioxide (CO2) and hydrogen (H2) adsorption studies on CuFeO2 thin films grown on Al2O3 (00.1) substrates were performed in ultrahigh vacuum using thermal programmed desorption (TPD). Growth of pure phase Delafossite CuFeO2 thin films on Al2O3 (00.1) substrates by pulsed laser deposition was systematically investigated as a function of growth temperature and oxygen pressure. CO2 and H2 TPD were performed on CuFeO2 -grown at 600°C and in 0.1mTorr pressure- indicating chemisorption of both gases on the oxide surface. TPD with a temperature ramp of 50 K/s showed a CO2 peak at 573 K and H2 peak at 823 K. The chemisorption of CO2 and H2 on the CuFeO2 surface is relevant to the potential use of this material in photocatalytic applications for H2 production and/or CO2 conversion. Fund from FONDECyT 1130372.

  10. Influence of Oxygen Partial Pressure during Processing on the Thermoelectric Properties of Aerosol-Deposited CuFeO2

    National Research Council Canada - National Science Library

    Thomas Stöcker; Jörg Exner; Michael Schubert; Maximilian Streibl; Ralf Moos

    2016-01-01

    .... For these purposes, CuFeO2 powders were synthetized using a conventional mixed-oxide technique. X-ray diffraction (XRD) studies were conducted to determine the crystal structures of the delafossites associated with the oxygen content during the synthesis...

  11. On the concentration and separation of the trace-elements Fe, Cu, Zn, Mn, Pb, Mo and Co : Solvent Extraction

    NARCIS (Netherlands)

    Erkelens, P.C. van

    1961-01-01

    Extractions with acetylacetone and diethyldithiocarbamate are described. Through the successive application of these reagents the constituents of biological ashes are concentrated and separated into the groups: (1) MoO4-2, (2) Fe+3, Cu+2 , (3) Mn+2, (4) Zn+2, (5) Pb+2, (6) Co+3 and (7)Na+, K+, Ca+2,

  12. Strength and electrical conductivity of deformation processed Cu-15**v**/oFe metal matrix composites produced by powder metallurgy/techniques

    Energy Technology Data Exchange (ETDEWEB)

    Jerman, G.A.

    1991-05-30

    Copper based deformation processed metal matrix composites have been recently developed which exhibit high strengths with high electrical conductivities. The high strengthening is achieved through the establishment of second phase fibers in a Cu matrix. The most suitable second phase materials are BCC metals such as Nb, Cr, V, Ta, and Fe. The most economically attractive combination is the Cu-Fe system. Previous attempts at processing Cu-Fe composites have been hampered by the presence of Fe dissolved in the Cu matrix. Because of the large detriment dissolved Fe poses to the conductivity of the Cu matrix, cast processing the undeformed composites has led to low overall conductivity. To overcome this obstacle, powder metallurgy techniques have been adopted to consolidate blended elemental Cu and Fe powders. By controlling the time and temperature of the consolidation process, a Cu-15{sup v}/oFe metal matrix composite has been developed which matches the strength and conductivity properties of a similar cast Cu-15{sup v}/oNb alloy. The highest achievable strength was 1462 MPa with an attendant conductivity of 59 %IACS. 49 figs.

  13. Bioaccessibility of Ca, Cu, Fe, Mg, Zn, and crude protein in beef, pork and chicken after thermal processing.

    Science.gov (United States)

    Menezes, Eveline A; Oliveira, Aline F; França, Celia J; Souza, Gilberto B; Nogueira, Ana Rita A

    2018-02-01

    The bioaccessibility of Ca, Cu, Fe, Mg, Zn, and crude protein was evaluated after submitting beef, pork, and chicken to five different thermal treatments. The bioaccessibility of crude protein and metals were simulated by using in vitro enzymatic digestion with a gastric fluid solution and dialysability approach. Inductively coupled plasma optical spectrometry was used to quantify the dialyzable fraction and the total mineral content after microwave-assisted digestion. Graphite furnace atomic absorption spectrometry quantified Cu in chicken dialyzable fraction. The increase of temperature and heat exposure period decreased the protein bioaccessibility. Considering the total and dialyzable fraction, beef is an important source of Cu, Fe, Mg, and Zn to the human diet. The results of Fourier-transform infrared spectroscopy indicated physical changes in the treated samples related to protein denaturation, which was probably responsible for the decreased bioaccessibility of minerals and protein, mainly at higher temperatures. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Ulva rigida’daki Ağır Metal (Pb, Cu, Zn ve Fe) Düzeyleri (Dardanel, Çanakkale)

    OpenAIRE

    Özden, Serkan; TUNÇER, Sezginer

    2015-01-01

    This study aims to determine the some heavy metal (Pb, Cu, Zn and Fe) concentrations in Ulva rigida at Çanakkale Strait (Dardanelles) to understand of the sea pollution. U. rigida has been collected from five different stations and in six seasonal periods between 2009 and 2013 years. Fe has the highest value heavy metal in this alge species. Mean seasonal results are arranged as: Fe > Zn > Cu > Pb. Heavy metal concentrations determined in U. rigida at five stations, respectively in G...

  15. The spin glass delafossite CuFe0.5V0.5O2: a dipolar glass?

    Science.gov (United States)

    Singh, Kiran; Maignan, Antoine; Simon, Charles; Hardy, Vincent; Pachoud, Elise; Martin, Christine

    2011-03-01

    The ferroelectric and spin glass properties of CuFe0.5V0.5O2 have been studied. Magnetization, ac magnetic susceptibility and specific heat measurements reveal a spin glass behavior (Tf = 20.5 K) for this delafossite. In CuFeO2, substitution of trivalent diamagnetic cations for Fe3 + is known to change the antiferromagnetic state and induce ferroelectricity. But partial occupation of the Fe3 + site by V3 + is responsible for disordered magnetism in CuFe0.5V0.5O2. The dielectric permittivity shows a frequency dependence reminiscent of relaxor ferroelectrics in which different cations occupy the same crystallographic site. Polarization measurements show the existence of a ferroelectric state below Tf with P5 K≈1.3 µC m - 2. These results point towards a relaxor-type ferroelectricity originating from a disordered array of magnetic cations. A clear coupling between electronic charges and spins is evidenced by the magnetodielectric effect.

  16. The spin glass delafossite CuFe(0.5)V(0.5)O(2): a dipolar glass?

    Science.gov (United States)

    Singh, Kiran; Maignan, Antoine; Simon, Charles; Hardy, Vincent; Pachoud, Elise; Martin, Christine

    2011-03-30

    The ferroelectric and spin glass properties of CuFe(0.5)V(0.5)O(2) have been studied. Magnetization, ac magnetic susceptibility and specific heat measurements reveal a spin glass behavior (T(f) = 20.5 K) for this delafossite. In CuFeO(2), substitution of trivalent diamagnetic cations for Fe(3 + ) is known to change the antiferromagnetic state and induce ferroelectricity. But partial occupation of the Fe(3 + ) site by V(3 + ) is responsible for disordered magnetism in CuFe(0.5)V(0.5)O(2). The dielectric permittivity shows a frequency dependence reminiscent of relaxor ferroelectrics in which different cations occupy the same crystallographic site. Polarization measurements show the existence of a ferroelectric state below T(f) with P(5 K)≈1.3 µC m( - 2). These results point towards a relaxor-type ferroelectricity originating from a disordered array of magnetic cations. A clear coupling between electronic charges and spins is evidenced by the magnetodielectric effect.

  17. Cu assisted stabilization and nucleation of L1 2 precipitates in Al 0.3 CuFeCrNi 2 fcc-based high entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gwalani, B.; Choudhuri, D.; Soni, V.; Ren, Y.; Styles, M.; Hwang, J. Y.; Nam, S. J.; Ryu, H.; Hong, S. H.; Banerjee, R.

    2017-05-01

    A detailed investigation of precipitation of the ordered L12 (γ’) phase in a Al0.3CrCuFeNi2 high entropy alloy (HEA), more generally referred to as a complex concentrated alloy (CCA), reveals the role of copper (Cu) on stabilization and precipitation of the ordered L12 ( γ’) phase. Detailed characterization via coupling of scanning and transmission electron microscopy, and atom probe tomography revealed novel insights into Cu clustering within the face-centered cubic matrix of this HEA, leading to heterogeneous nucleation sites for the γ’ precipitates. The subsequent partitioning of Cu into the γ’ precipitates indicates their stabilization is due to Cu addition. The γ’ order-disorder transition temperature was determined to be ~930 _C in this alloy, based on synchrotron diffraction experiments, involving in situ annealing. The growth and high temperature stability of the γ’ precipitates was also confirmed via systematic scanning electron microscopy investigations of samples annealed at temperatures in the range of 700-900 oC. The role of Cu revealed by this study can be employed in the design of precipitation strengthened HEAs, as well as in a more general sense applied to other types of superalloys, with the objective of potentially enhancing their mechanical properties at room and elevated temperatures

  18. A new strategy to construct a C=C-CF3 subunit via CuBr-catalyzed domino reaction of homopropargyl amines: an efficient synthesis of trifluoromethyl containing building blocks 4-trifluoromethyl-2,3-dihydro-pyrroliums.

    Science.gov (United States)

    Ge, Guang-Cun; Huang, Xiao-Jun; Ding, Chang-Hua; Wan, Shi-Li; Dai, Li-Xin; Hou, Xue-Long

    2014-03-21

    A new strategy for the construction of a C=C-CF3 subunit has been developed via CuBr-catalyzed domino cyclization-trifluoromethylation of homopropargyl amines with Umemoto's reagent. 4-Trifluoromethyl-2,3-dihydro-pyrroliums were produced in high yields. The usefulness of these products has been demonstrated by the transformation of them into various other trifluoromethylated molecules.

  19. Rapid decolorization of dye Orange G by microwave enhanced Fenton-like reaction with delafossite-type CuFeO2.

    Science.gov (United States)

    Cai, Mei-Qiang; Zhu, Yi-Zu; Wei, Zong-Su; Hu, Jian-Qiang; Pan, Sheng-Dong; Xiao, Rui-Yang; Dong, Chun-Ying; Jin, Mi-Cong

    2017-02-15

    Bimetallic oxide CuFeO2 as a new heterogeneous catalyst has shown much higher catalytic ability for activating peroxide than single-metal oxides. The present work demonstrated a synergistic microwave (MW) enhanced Fenton-like process with CuFeO2 for rapid decolorization of azo dye Orange G (OG). The MW irradiation dramatically enhanced the OG degradation efficiency, achieving 99.9% decolorization within 15min at pH5. The XRD analysis of reused CuFeO2, together with metal leaching tests, indicated merits of recycling for CuFeO2. The subsequent surface element analysis by XPS for fresh and used CuFeO2 showed a complex network for reactions between copper-iron redox pairs and surface hydroxyl groups, leading to a synergistic Fenton-like system accelerated by MW irradiation. In the CuFeO2 initiated Fenton-like reactions, several oxidant species (i.e., OH, O2-, electron hole, and FeIVO) responsible to the OG oxidation were identified by quenching experiments, showing the MW generated high temperature and "hot spots" enhanced the yield of OH by generation of electron-hole pairs. Further, the 26 detected degradation products confirmed the OH dominant oxidation of OG. This study shows that the MW-enhanced Fenton-like reaction using CuFeO2 has potential applications for rapid decolorization of dye effluent. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Icosahedral Pt-centered Pt13 and Pt19 carbonyl clusters decorated by [Cd5(μ-Br)5Br(5-x)(solvent)x]x+ rings reminiscent of the decoration of Au-Fe-CO and Au-thiolate nanoclusters: a unifying approach to their electron counts.

    Science.gov (United States)

    Femoni, Cristina; Iapalucci, Maria Carmela; Longoni, Giuliano; Zacchini, Stefano; Zarra, Salvatore

    2011-03-02

    The new [Pt(13)(CO)(12){Cd(5)(μ-Br)(5)Br(2)(dmf)(3)}(2)](2-) and [Pt(19)(CO)(17){Cd(5)(μ-Br)(5)Br(3)(Me(2)CO)(2)}{Cd(5)(μ-Br)(5)Br(Me(2)CO)(4)}](2-) clusters have been obtained in good yields by reaction of [Pt(12)(CO)(24)](2-) with CdBr(2)·H(2)O in dmf at 90 °C and structurally characterized by X-ray diffraction. Their structures consist of a Pt-centered Pt(13)(CO)(12) icosahedron and a Pt(19)(CO)(17) interpenetrated double icosahedron, respectively, decorated by two Cd(5)(μ-Br)(5)Br(5-x)(solvent)(x) rings. Their surface decoration may be related to that of Au-Fe-CO clusters as well as to the staple motifs stabilizing gold-thiolates nanoclusters. An oversimplified and unifying approach to interpret their electron count is suggested.

  1. Effect of sintering temperature and vinca petals extract on structural and magnetic properties of delafossite CuFeO2

    Science.gov (United States)

    Dhruv, Preksha N.; Solanki, Neha; Kulkarni, Shailja; Jotania, R. B.

    2016-05-01

    Delafossite CuFeO2 multiferroic powder was synthesized using Sol-Gel auto combustion method. Influence of vinca flower petals extract on structural and magnetic property of CuFeO2 were investigated. X-ray analysis of normal samples (synthesized without presence of vinca petals extract) shows formation of hematite and ferrite phases while the sample synthesized in presence of vinca petals extract show only mono phase. The absorption bands in FTIR spectra present between 510-460 cm-1 in both the samples are due to stretching of Fe-O vibrations. VSM analysis shows that the squareness ratio (Mr/Ms) of the sample prepared using vinca petals extract obtains value of squareness ratio < 0.5, which attributes multi domain formation of samples.

  2. Hyperfine fields and field gradients of thin films of face-centred-cubic Fe on Cu(001)

    CERN Document Server

    Gomez, J A

    2002-01-01

    The discrete variational method in density functional theory was employed to perform first-principles electronic structure calculations for embedded clusters representing thin films of face-centred-cubic Fe on a Cu(001) substrate. 3, 4 and 5 ML of Fe were investigated; the ferromagnetic and several types of antiferromagnetic spin configurations were considered. Layer-by-layer calculations of the contact and dipolar components of the magnetic hyperfine field are reported, as well as electric-field gradients at the surface and interface layers. Significant field gradients were found at the surfaces. Clusters modelling the interdiffusion of Fe and Cu between two layers at the interface were also investigated, to determine the effects on the properties.

  3. CeLa enhanced corrosion resistance of Al-Cu-Mn-Mg-Fe alloy for lithium battery shell

    Science.gov (United States)

    Du, Jiandi; Ding, Dongyan; Zhang, Wenlong; Xu, Zhou; Gao, Yongjin; Chen, Guozhen; Chen, Weigao; You, Xiaohua; Chen, Renzong; Huang, Yuanwei; Tang, Jinsong

    2017-11-01

    Effects of CeLa addition on the localized corrosion and electrochemical corrosion behavior of Al-Cu-Mn-Mg-Fe lithium battery shell alloy were investigated by immersion testing and electrochemical testing in 0.6 M NaCl solution at different temperatures. Experimental results indicated that CeLa addition resulted in the formation of AlCuCe/La (Al8Cu4Ce and Al6Cu6La) local cathodes and corrosion activity of the main intermetallic particles decreased in the order of Al2CuMg, AlCuCe/La, Al6(Mn, Fe). Corrosion potential shifted positively due to CeLa alloying. Corrosion current density of the CeLa-containing alloy was lower than that of the CeLa-free alloy at room temperature. At room temperature, there was no obvious surface passivation for both alloys. At 80 °C CeLa addition resulted in a wide passive region at the anode polarization region. Electrochemical impedance spectroscopy (EIS) analysis also indicated that corrosion resistance of the CeLa-containing alloy was much higher than that of the CeLa-free alloy.

  4. Synthesis of magnetic porous Fe3O4/C/Cu2O composite as an excellent photo-Fenton catalyst under neutral condition.

    Science.gov (United States)

    Chai, Fanfan; Li, Keyan; Song, Chunshan; Guo, Xinwen

    2016-08-01

    Magnetic porous Fe3O4/C/Cu2O composites were prepared by a simple two-step process. Porous Fe3O4/C was synthesized via calcining iron tartrate precursor and then Cu2O was composited with Fe3O4/C by a precipitation-reduction method. The as-prepared samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) elemental mapping. Results show that Fe3O4/C has porous nanorod structure, which is composed of numerous small nanoparticles of about 50nm. Fe3O4 and carbon are uniformly distributed in the Fe3O4/C/Cu2O composite and Cu2O is dispersed on the surface of Fe3O4/C. Fe3O4/C/Cu2O composite exhibits excellent photo-Fenton catalytic performance for the degradation of methylene blue (MB) under visible light irradiation and neutral pH conditions, and MB (100mg/L) could be almost completely removed within 60min. The composite shows good recyclability and could be conveniently separated by an applied magnetic field. These results demonstrate that the Fe3O4/C/Cu2O composite is a powerful Fenton-like catalyst for degradation of organic pollutants from wastewater. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. AC and DC-shielding properties for the Ni80Fe20/Cu film structures

    Science.gov (United States)

    Trukhanov, A. V.; Grabchikov, S. S.; Solobai, A. A.; Tishkevich, D. I.; Trukhanov, S. V.; Trukhanova, E. L.

    2017-12-01

    Multilayered Ni80Fe20/Cu film shields were obtained via electrochemistry method with different thickness and number of partial magnetic layers. Magnetic properties and shielding characteristics were investigated as well as function of thickness and number of layers. Difference in magnetic properties for Ni80Fe20 films with different thickness is due to formation of defect layers on the top and bottom film surfaces during electrodeposition processes. These layers can be characterized as layers with high density defects (as a result poor iron content). Main deviation in magnetic properties is typical for thinner films. It was measured DC and AC shielding and results discussed. Maximal value of DC-shielding effectiveness was observed for multilayered samples with small number magnetic layers with large thickness (80-400 μm). The minimal value of DC-shielding effectiveness was observed for the multilayered sample with the minimum thickness of the magnetic layer (5 μm) and maximal number of the layers (80 layers). It is in good agreement with shunting mechanism. In low frequency range maximal values of AC-shielding effectiveness were observed like in case of DC-shielding for samples with small number magnetic layers with large thickness. With frequency increasing the situation was radically changed and AC-shielding effectiveness was higher for samples with maximal number of layers. In the frequency range above 40 kHz AC-shielding effectiveness was sharply decreased due to sharply decreasing of permeability value. As a result it leads to decrease of absorption loses (SEabs.). It was discussed the main shielding mechanisms for multilayered Ni80Fe20/Cu film samples under different external influences. Main contribution in electromagnetic shielding in the range 300 Hz-20 kHz is absorption and reflection processes. In the range 20 kHz-50 kHz main shielding mechanisms are reflection and re-reflection. For 300 Hz-50 kHz frequency range most appropriate to use multilayered

  6. Effect of Magnetic Field on Surface Morphology and Magnetic Properties of FeCu/Cu Nano layers Prepared by Electrodeposition Technique: Investigation of Magneto-hydrodynamic Effect

    Directory of Open Access Journals (Sweden)

    M. Merikhi

    2015-10-01

    Full Text Available In this paper, the effect of magnetic field on the morphology, structure and magnetic properties of electrodeposited FeCu/Cu thin films was investigated. The films were deposited on Au2PdAg/glass substrates using electrodeposition technique in potentiostatic control. The magnetic fields of 5000 and 7000 Oe were applied on deposition bath during deposition. Two series of thin films were prepared in the same deposition conditions, one in the presence and the other in absence of magnetic field and the products were compared. The results indicate that applying the magnetic field has a significant effect on the growth process, i.e. morphology, crystal structure and magnetic properties of the films. The morphology and structure of the FeCu/Cu Nano layers were studied using X-ray diffraction (XRD and scanning electron microscopy (SEM. The weight percentages of the elements in the deposited multilayers were determined by energy dispersive X-ray spectroscopy (EDS. Magnetic properties of thin films were studied using the vibrating sample magnetometer (VSM.

  7. Effect of Cu{sup 2+} and Fe{sup 3+} for drug delivery: Decreased binding affinity of ilaprazole to bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yuping [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Shi Shuyun, E-mail: shuyshi@gmail.com [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Resources Chemistry of Nonferrous Metals, Central South University, Changsha 410083 (China); Huang Kelong, E-mail: hunagkelong@yahoo.com.cn [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Chen Xiaoqin [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Peng Mijun, E-mail: Pengmj163@163.com [Key Laboratory of Hunan Forest Products and Chemical Industry Engineering, Jishou University, Zhangjiajie 427000 (China)

    2011-09-15

    The interaction between ilaprazole and bovine serum albumin (BSA) has been investigated in the absence and presence of Cu{sup 2+} or Fe{sup 3+} by means of fluorescence spectroscopy. The fluorescence intensity of BSA decreased remarkably with no obvious BSA maximum emission wavelength shift by adding ilaprazole. Similar fluorescence shape with larger quenching extent of BSA was observed with increasing concentrations of ilaprazole in the presence of Cu{sup 2+} or Fe{sup 3+}. The quenching constants and affinities of ilaprazole with BSA in the presence of Cu{sup 2+} and Fe{sup 3+} decreased. The decreased affinity and unchangeable binding distance in the presence of metal ions may result from a competitive binding between ilaprazole and metal ions. The results indicated that the presence of Cu{sup 2+} or Fe{sup 3+} could improve ilaprazole's maximum effects, which may have relevant consequence in rationalizing dosage for patients with gastric and duodenal ulcers. - Highlights: > Ilaprazole affinity for BSA has been investigated with or without Cu{sup 2+} or Fe{sup 3+}. > Cu{sup 2+} and Fe{sup 3+} decreased the affinities of ilaprazole to BSA. > Cu{sup 2+} and Fe{sup 3+} had competitive binding site with ilaprazole.

  8. Investigations of the EPR parameters for the tetrahedral [FeX4]- clusters in AgX (X=Cl, Br

    Directory of Open Access Journals (Sweden)

    Z.-H. Zhang

    2012-03-01

    Full Text Available The EPR parameters g factors and the superhyperfine parameters for the tetrahedral [FeX4]- clusters in AgX (X=Cl, Br are theoretically investigated from the perturbation formulas of these parameters for a 3d5 ion under tetrahedra by considering both the crystal-field and charge transfer contributions.The related model parameters are quantitatively determined from the cluster approach in a uniform way. The g-shift Δg (=g-gs, where gs≈2.0023 is the spin only value from the charge transfer contribution is opposite (positive in sign and much larger in magnitude as compared with that from the crystal-field one. The importance of the charge transfer contribution increases rapidly with increasing the covalency and the spin-orbit coupling coefficient of the ligand and thus exhibits the order of AgCl < AgBr. The unpaired spin densities of the halogen ns, npσ and npπ orbitals are quantitatively determined from the related molecular orbital coefficients based on the cluster approach.

  9. A facile FeBr3 based photoATRP for surface modification of mesoporous silica nanoparticles for controlled delivery cisplatin

    Science.gov (United States)

    Huang, Long; Liu, Meiying; Mao, Liucheng; Huang, Qiang; Huang, Hongye; Zeng, Guangjian; Tian, Jianwen; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

    2018-03-01

    Mesoporous silica nanoparticles (MSNs) should be one of the most important materials for biomedical application owing to their high specific surface area, regular porous structure, adjustable pore size and chemical inert. However, the biomedical applications of unmodified MSNs are largely impeded for their poor hydrophilicity and lack of functional groups. In this work, a novel photo-initiated atom transfer radical polymerization (ATRP) strategy has been reported for modified mesoporous silica nanoparticles (MSNs) with hydrophilicility copolymers using FeBr3 as the novel photocatalyst and itaconic acid (IA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) as monomers. Because of the hydrophilicity and anticancer agent cis-dichlorodiamineplatinum(II) (CDDP) loading capacity of poly(MPC-co-IA), the controlled drug delivery applications MSNs-NH2-poly(MPC-co-IA) composites toward CDDP were further investigated. A series of characterization results demonstrated that MSNs-NH2-poly(MPC-co-IA) composites can be successfully fabricated through the novel photo-initiated ATRP. MSNs-NH2-poly(MPC-co-IA) composites showed obvious enhancement of water dispersibility, desirable biocompatibility, high drug loading capability, making them great potential for controlled drug delivery of CDDP. Moreover, as compared with the traditional ATRP, that using the transition metal ions and organic ligands as the catalysis systems in elevated temperature, our method provides a more facile, benign and cost-effective route for fabrication of multifunctional MSNs with great potential for biomedical applications. Finally, this FeBr3 based photoATRP strategy should be further extended for the fabrication of many other polymeric composites owing to its good monomer adoptability.

  10. Colour centres in LiNbO{sub 3}:Fe and LiNbO{sub 3}:Cu crystals irradiated by {sup 12}C ions

    Energy Technology Data Exchange (ETDEWEB)

    Potera, P. [Institute of Physics, University of Rzeszow, 16A Rejtana St., 35310 Rzeszow (Poland)]. E-mail: ppotera@univ.rzeszow.pl; Ubizskii, S. [Lviv Polytechnic National University, 12 Bandera St., 79013 Lviv (Ukraine); Sugak, D. [Lviv Polytechnic National University, 12 Bandera St., 79013 Lviv (Ukraine); Scientific Research Company ' Carat' , 202, Stryjska St., 79031 Lviv (Ukraine); Lukasiewicz, T. [Institute of Electronic Materials Technology, 133 Wolczynska St., 01919 Warsaw (Poland)

    2007-02-15

    The present work is devoted to the investigation of optical absorption of pure and doped LiNbO{sub 3} (LN) single crystals in the spectral range 5000-32000cm{sup -1} induced under influence of the {sup 12}C ions irradiation with energy 4.5MeV/u (MeV per nucleon) and a fluence 2x10{sup 9}cm{sup -2} at room temperature. It was found that no remarkable absorption changes occur in pure and Mg-doped LN crystals, but in Fe- and Cu-doped ones. The induced additional absorption in LN:Fe crystals is attributed with Fe ions reducing Fe{sup 3+}->Fe{sup 2+} occurring simultaneously with hole centres formation O{sup -}, while only Cu{sup 2+}->Cu{sup +} reduction was observed in LN:Cu crystals.

  11. Analysis alloy quasicrystalline Al62,2 Cu25,3 Fe12,5 for steam reforming of methanol

    Directory of Open Access Journals (Sweden)

    Lourdes Cristina Lucena Agostinho Jamshidi

    2015-10-01

    Full Text Available This study shows a good performance of quasicrystal Al62,2Cu25,3Fe12,5 as catalyst in catalytic reactions. This metal catalyst, without being leached with acid or base, with dry stoichiometric composition, Al62,2Cu25,3Fe12,5 is revealed among the reactions which occurred to be a partial oxidation; and promoted the formation of products: methanol, methanal + methanoic acid, water and dimethyl ether. For this research were used such experimental techniques as X-ray Diffraction (XRD to follow the evolution of the alloy phase, the Scanning Electron Microscopy (SEM that provides the study of surface microstructure, and Transmission Electron Microscopy (MET. All these techniques study the morphology of the internal phase, and defect a quasicrystalline nucleus. Catalytic tests of methanol conversion and selectivity intermediate products were obtained using this catalyst quasicrystal. The activity and stability of quasicrystal catalyst for reforming of methanol vapor show sufficient growth compared to the other catalysts. Fe and Cu species are highly dispersed in the homogeneous layer of quasicrystal catalyst which increase the catalytic activity and suppress the aggregation of Cu particles. We suppose that the quasicrystal can be a good catalyst used in a catalytic steam reforming, with high catalytic activity and excellent thermal stability.

  12. Facile synthesis, characterization and magnetic property of CuFe12O19 nanostructures via a sol-gel auto-combustion process

    Science.gov (United States)

    Ansari, Fatemeh; Sobhani, Azam; Salavati-Niasari, Masoud

    2016-03-01

    Copper hexaferrite (CuFe12O19) nanostructures were prepared by a simple route utilizing maltose-assisted sol-gel process. The morphology, phase structure, composition and purity of nanostructures can be controlled by type of surfactant and also adjusting the Cu:surfactant, Cu:Fe and Cu:reductant ratios. The bean-shape structures are formed in the absence of the surfactant when the molar ratio of Cu:Fe and Cu:reductant are 1:12 and 1:26, respectively. The agglomerated spherical nanoparticles with diameters ranging from 7 to 20 nm are obtained in the presence of triplex, when ratio of Cu:reductant is 1:26. In the absence of surfactant and also in the presence of triplex, the samples are found to be CuFe12O19. When polymer is used, there are still the peaks of CuFe12O19 and also some boad peaks in XRD patterns, because of the small size and encapsulation of nanostructures with polymer. Magnetic measurments show superparamagnetic behavior for the all samples. The Ms for the samples obtained in the presence of polymer shows that the coating of magnetic nanostructures does not always increase Ms. FT-IR frequency bands in the range 463-626, 607 and 542 cm-1 correspond to the formation of metal oxides in ferrites.

  13. Conditions and mechanisms for the formation of nano-sized Delafossite (CuFeO2) at temperatures ≤90 °C in aqueous solution

    Science.gov (United States)

    John, Melanie; Heuss-Aßbichler, Soraya; Ullrich, Aladin

    2016-02-01

    In this study, we present the mechanism of CuFeO2 formation in aqueous solution at low temperatures ≤90 °C, using sulfate salts as reactants. Furthermore, we demonstrate the influence of experimental conditions (alkalization, reaction and ageing temperature and time) on the synthesized nanoparticles. In all cases, GR-SO4, a Fe(II-III) layered double hydroxysulphate (Fe2+4Fe3+2(OH)12·SO4) and Cu2O precipitate first. During further OH- supply GR-SO4 oxidizes and forms Fe10O14(OH)2, Cu2O and CuFeO2 crystals. Due to the high pH further CuFeO2 crystals grow at the cost of the unstable intermediate products. The reaction rate increases with increasing ageing temperature, reaction pH and, in particular, NaOH concentrations in the solution. As a result, highly crystalline CuFeO2 (3R and 2H polytypes) nanoparticles showing hexagonal morphology can be synthesized at 70 °C within 10 h or at 50 °C within 1 week. The formation of 2H polytype is favored by additional OH- supply during the pH-stat time and rather low temperatures.

  14. A comprehensive study of magnetic exchanges in the layered oxychalcogenides Sr 3 Fe 2 O 5 Cu 2 Q 2 ( Q = S, Se)

    Energy Technology Data Exchange (ETDEWEB)

    Lü, Minfeng; Mentré, Olivier; Gordon, Elijah E.; Whangbo, Myung-Hwan; Wattiaux, Alain; Duttine, Mathieu; Tiercelin, Nicolas; Kabbour, Houria

    2017-12-01

    The layered oxysulfide Sr3Fe2O5Cu2S2 was prepared, and its crystal structure and magnetic properties were characterized by synchrotron X-ray diffraction (XRD), powder neutron diffraction (PND), Mössbauer spectroscopy measurements and by density functional theory (DFT) calculations. In addition, the spin exchange interactions leading to the ordered magnetic structure of Sr3Fe2O5Cu2S2 were compared with those of its selenium analogue Sr3Fe2O5Cu2Se2. The oxysulfide Sr3Fe2O5Cu2S2 adopts a G-type antiferromagnetic (AFM) structure at a temperature in the range 485–512 K, which is comparable with the three-dimensional (3D) AFM ordering temperature, TN ≈ 490 K, found for Sr3Fe2O5Cu2Se2. Consistent with this observation, the spin exchange interactions of the magnetic (Sr3Fe2O5)2+ layers are slightly greater (but comparable) for oxysulfide than for the oxyselenide. Attempts to reduce or oxidize Sr3Fe2O5Cu2S2 using topochemical routes yield metallic Fe.

  15. Co-reduction of Copper Smelting Slag and Nickel Laterite to Prepare Fe-Ni-Cu Alloy for Weathering Steel

    Science.gov (United States)

    Guo, Zhengqi; Pan, Jian; Zhu, Deqing; Zhang, Feng

    2018-02-01

    In this study, a new technique was proposed for the economical and environmentally friendly recovery of valuable metals from copper smelting slag while simultaneously upgrading nickel laterite through a co-reduction followed by wet magnetic separation process. Copper slag with a high FeO content can decrease the liquidus temperature of the SiO2-Al2O3-CaO-MgO system and facilitate formation of liquid phase in a co-reduction process with nickel laterite, which is beneficial for metallic particle growth. As a result, the recovery of Ni, Cu, and Fe was notably increased. A crude Fe-Ni-Cu alloy with 2.5% Ni, 1.1% Cu, and 87.9% Fe was produced, which can replace part of scrap steel, electrolytic copper, and nickel as the burden in the production of weathering steel by an electric arc furnace. The study further found that an appropriate proportion of copper slag and nickel laterite in the mixture is essential to enhance the reduction, acquire appropriate amounts of the liquid phase, and improve the growth of the metallic alloy grains. As a result, the liberation of alloy particles in the grinding process was effectively promoted and the metal recovery was increased significantly in the subsequent magnetic separation process.

  16. CH4 dissociation in the early stage of graphene growth on Fe-Cu(100) surface: Theoretical insights

    Science.gov (United States)

    Tian, Baoyang; Liu, Tianhui; Yang, YanYan; Li, Kai; Wu, Zhijian; Wang, Ying

    2018-01-01

    The mechanism of CH4 dissociation and carbon nucleation process on the Fe doped Cu(100) surface were investigated systematically by using the density functional theory (DFT) calculations and microkinetic model. The activity of the Cu(100) surface was improved by the doped Fe atom and the atomic Fe on the Fe-Cu(100) surface was the reaction center due to the synergistic effect. In the dissociation process of CH4, CH3 → CH2 + H was regarded as the rate-determining step. The results obtained from the microkinetic model showed that the coverage of CHx(x = 1-3) was gradually decreased with the temperature increasing and CH3 was always the major intermediate at the broad range of the temperature (from 1035 to 1080 °C) and the ratio of H2/CH4 (from 0 to 5). It is also found that the reaction rates were increased with the temperature increasing. However, the reaction rates were reduced (or increased) at the range of H2/CH4 = 0-0.2 (or H2/CH4 > 0.2). It is noted that controlling the H2 partial pressure was an effective method to regulate the major intermediates and reaction rates of CH4 dissociation and further influence the growing process of graphene.

  17. Co-reduction of Copper Smelting Slag and Nickel Laterite to Prepare Fe-Ni-Cu Alloy for Weathering Steel

    Science.gov (United States)

    Guo, Zhengqi; Pan, Jian; Zhu, Deqing; Zhang, Feng

    2017-11-01

    In this study, a new technique was proposed for the economical and environmentally friendly recovery of valuable metals from copper smelting slag while simultaneously upgrading nickel laterite through a co-reduction followed by wet magnetic separation process. Copper slag with a high FeO content can decrease the liquidus temperature of the SiO2-Al2O3-CaO-MgO system and facilitate formation of liquid phase in a co-reduction process with nickel laterite, which is beneficial for metallic particle growth. As a result, the recovery of Ni, Cu, and Fe was notably increased. A crude Fe-Ni-Cu alloy with 2.5% Ni, 1.1% Cu, and 87.9% Fe was produced, which can replace part of scrap steel, electrolytic copper, and nickel as the burden in the production of weathering steel by an electric arc furnace. The study further found that an appropriate proportion of copper slag and nickel laterite in the mixture is essential to enhance the reduction, acquire appropriate amounts of the liquid phase, and improve the growth of the metallic alloy grains. As a result, the liberation of alloy particles in the grinding process was effectively promoted and the metal recovery was increased significantly in the subsequent magnetic separation process.

  18. Influence of Oxygen Partial Pressure during Processing on the Thermoelectric Properties of Aerosol-Deposited CuFeO2

    Science.gov (United States)

    Stöcker, Thomas; Exner, Jörg; Schubert, Michael; Streibl, Maximilian; Moos, Ralf

    2016-01-01

    In the field of thermoelectric energy conversion, oxide materials show promising potential due to their good stability in oxidizing environments. Hence, the influence of oxygen partial pressure during synthesis on the thermoelectric properties of Cu-Delafossites at high temperatures was investigated in this study. For these purposes, CuFeO2 powders were synthetized using a conventional mixed-oxide technique. X-ray diffraction (XRD) studies were conducted to determine the crystal structures of the delafossites associated with the oxygen content during the synthesis. Out of these powders, films with a thickness of about 25 µm were prepared by the relatively new aerosol-deposition (AD) coating technique. It is based on a room temperature impact consolidation process (RTIC) to deposit dense solid films of ceramic materials on various substrates without using a high-temperature step during the coating process. On these dense CuFeO2 films deposited on alumina substrates with electrode structures, the Seebeck coefficient and the electrical conductivity were measured as a function of temperature and oxygen partial pressure. We compared the thermoelectric properties of both standard processed and aerosol deposited CuFeO2 up to 900 °C and investigated the influence of oxygen partial pressure on the electrical conductivity, on the Seebeck coefficient and on the high temperature stability of CuFeO2. These studies may not only help to improve the thermoelectric material in the high-temperature case, but may also serve as an initial basis to establish a defect chemical model. PMID:28773351

  19. Influence of leaching on surface composition, microstructure, and valence band of single grain icosahedral Al-Cu-Fe quasicrystal

    Science.gov (United States)

    Lowe, M.; Yadav, T. P.; Fournée, V.; Ledieu, J.; McGrath, R.; Sharma, H. R.

    2015-03-01

    The use of quasicrystals as precursors to catalysts for the steam reforming of methanol is potentially one of the most important applications of these new materials. To develop application as a technology requires a detailed understanding of the microscopic behavior of the catalyst. Here, we report the effect of leaching treatments on the surface microstructure, chemical composition, and valence band of the icosahedral (i-) Al-Cu-Fe quasicrystal in an attempt to prepare a model catalyst. The high symmetry fivefold surface of a single grain i-Al-Cu-Fe quasicrystal was leached with NaOH solution for varying times, and the resulting surface was characterized by x-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The leaching treatments preferentially remove Al producing a capping layer consisting of Fe and Cu oxides. The subsurface layer contains elemental Fe and Cu in addition to the oxides. The quasicrystalline bulk structure beneath remains unchanged. The subsurface gradually becomes Fe3O4 rich with increasing leaching time. The surface after leaching exhibits micron sized dodecahedral cavities due to preferential leaching along the fivefold axis. Nanoparticles of the transition metals and their oxides are precipitated on the surface after leaching. The size of the nanoparticles is estimated by high resolution transmission microscopy to be 5-20 nm, which is in agreement with the AFM results. Selected area electron diffraction (SAED) confirms the crystalline nature of the nanoparticles. SAED further reveals the formation of an interface between the high atomic density lattice planes of nanoparticles and the quasicrystal. These results provide an important insight into the preparation of model catalysts of nanoparticles for steam reforming of methanol.

  20. Electronic and spin dynamics in the insulating iron pnictide NaFe0.5Cu0.5As

    Science.gov (United States)

    Zhang, Shunhong; He, Yanjun; Mei, Jia-Wei; Liu, Feng; Liu, Zheng

    2017-12-01

    NaFe0.5Cu0.5As represents a rare exception in the metallic iron pnictide family, in which a small insulating gap is opened. Based on first-principles study, we provide a comprehensive theoretical characterization of this insulating compound. The Fe3 + spin degree of freedom is quantified as a quasi-one-dimensional (1D) S =5/2 Heisenberg model. The itinerant As hole state is downfolded to a px y-orbital hopping model on a square lattice. An orbital-dependent Hund's coupling between the spin and the hole is revealed. Several important material properties are analyzed, including (a) the factors affecting the small p -d charge-transfer gap; (b) the role of extra interchain Fe atoms; and (c) quasi-1D spin excitation in the Fe chains. The experimental manifestations of these properties are discussed.

  1. Conditions and mechanisms for the formation of nano-sized Delafossite (CuFeO{sub 2}) at temperatures ≤90 °C in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    John, Melanie, E-mail: melanie.john@min.uni-muenchen.de [Department of Earth and Environmental Sciences, Ludwig-Maximilians -University Munich, Theresienstr. 41, 80333 München (Germany); Heuss-Aßbichler, Soraya [Department of Earth and Environmental Sciences, Ludwig-Maximilians -University Munich, Theresienstr. 41, 80333 München (Germany); Ullrich, Aladin [Department of Experimental Physics II, University Augsburg, Universitätsstr. 1, 86159 Augsburg (Germany)

    2016-02-15

    In this study, we present the mechanism of CuFeO{sub 2} formation in aqueous solution at low temperatures ≤90 °C, using sulfate salts as reactants. Furthermore, we demonstrate the influence of experimental conditions (alkalization, reaction and ageing temperature and time) on the synthesized nanoparticles. In all cases, GR–SO{sub 4}, a Fe(II–III) layered double hydroxysulphate (Fe{sup 2+}{sub 4}Fe{sup 3+}{sub 2}(OH){sub 12}·SO{sub 4}) and Cu{sub 2}O precipitate first. During further OH{sup −} supply GR–SO{sub 4} oxidizes and forms Fe{sub 10}O{sub 14}(OH){sub 2}, Cu{sub 2}O and CuFeO{sub 2} crystals. Due to the high pH further CuFeO{sub 2} crystals grow at the cost of the unstable intermediate products. The reaction rate increases with increasing ageing temperature, reaction pH and, in particular, NaOH concentrations in the solution. As a result, highly crystalline CuFeO{sub 2} (3R and 2H polytypes) nanoparticles showing hexagonal morphology can be synthesized at 70 °C within 10 h or at 50 °C within 1 week. The formation of 2H polytype is favored by additional OH{sup −} supply during the pH-stat time and rather low temperatures. - Highlights: • We solve the formation mechanism of pure CuFeO{sub 2} using sulfates as reactants. • CuFeO{sub 2} nanoparticles crystallize on cost of green rust, Fe{sub 10}O{sub 14}(OH){sub 2} and Cu{sub 2}O. • The reaction rate increases with increasing temperature and OH- concentration. • CuFeO{sub 2} nanoparticles form at 50 °C within one week and at 70 °C within 10 h. • 2H-polytype of CuFeO{sub 2} is favored by additional NaOH supply during pH-stat-time.

  2. A nuclear microscopy study of trace elements Ca, Fe, Zn and Cu in atherosclerosis

    Science.gov (United States)

    Watt, F.; Rajendran, R.; Ren, M. Q.; Tan, B. K. H.; Halliwell, B.

    2006-08-01

    Quantitative mapping of trace elements Ca, Fe, Zn and Cu can be achieved in biological tissue using a nuclear microprobe. Presented here is a brief review of the work we have carried out in the last decade using the nuclear microscope to try and elucidate the role of trace elements Fe, Zn, Cu and Ca in induced atherosclerosis in New Zealand White rabbits fed on a 1% cholesterol diet. The lesions were studied using nuclear microscopy, incorporating a combination of ion beam techniques: particle induced X-ray emission (PIXE), Rutherford backscattering spectrometry (RBS) and scanning transmission ion microscopy (STIM). Iron is present in early lesions at concentrations around seven times higher than the artery wall. Measurements of localized lesion iron concentrations were observed to be highly correlated with the depth of the lesion in the artery wall for each individual animal, implying that local elevated concentrations may provide an accelerated process of atherosclerosis in specific regions of the artery. When the rabbits were kept mildly anaemic, thereby reducing iron levels in the lesion, the progression of the disease was significantly slowed. Iron chelation using desferal showed that early treatment (three weeks into the high fat diet) for relatively long periods (nine weeks) significantly retarded the progression of the disease. Zinc is depleted in the lesion and is also observed to be anti-correlated with local lesion development and feeding the rabbits on a high fat diet with zinc supplements inhibited lesion development, although since no significant increase in lesion zinc levels was measured, this anti-atherosclerotic effect may be indirect. Copper, measured at low levels (∼3 ppm) in the early lesion, is also depleted compared to the artery wall, suggesting that it is not a major factor in atherogenesis. Calcium is also depleted in early lesions, although at a later stage mineral deposition (hydroxyapatite) is observed to take place in the lesion

  3. Beneficial Role of Copper in the Enhancement of Durability of Ordered Intermetallic PtFeCu Catalyst for Electrocatalytic Oxygen Reduction.

    Science.gov (United States)

    Arumugam, Balamurugan; Tamaki, Takanori; Yamaguchi, Takeo

    2015-08-05

    Design of Pt alloy catalysts with enhanced activity and durability is a key challenge for polymer electrolyte membrane fuel cells. In the present work, we compare the durability of the ordered intermetallic face-centered tetragonal (fct) PtFeCu catalyst for the oxygen reduction reaction (ORR) relative to its counterpart bimetallic catalysts, i.e., the ordered intermetallic fct-PtFe catalyst and the commercial catalyst from Tanaka Kikinzoku Kogyo, TKK-PtC. Although both fct catalysts initially exhibited an ordered structure and mass activity approximately 2.5 times higher than that of TKK-Pt/C, the presence of Cu at the ordered intermetallic fct-PtFeCu catalyst led to a significant enhancement in durability compared to that of the ordered intermetallic fct-PtFe catalyst. The ordered intermetallic fct-PtFeCu catalyst retained more than 70% of its mass activity and electrochemically active surface area (ECSA) over 10 000 durability cycles carried out at 60 °C. In contrast, the ordered intermetallic fct-PtFe catalyst maintained only about 40% of its activity. The temperature of the durability experiment is also shown to be important: the catalyst was more severely degraded at 60 °C than at room temperature. To obtain insight into the observed enhancement in durability of fct-PtFeCu catalyst, a postmortem analysis of the ordered intermetallic fct-PtFeCu catalyst was carried out using scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDX) line scan. The STEM-EDX line scans of the ordered intermetallic fct-PtFeCu catalyst over 10 000 durability cycles showed a smaller degree of Fe and Cu dissolution from the catalyst. Conversely, large dissolution of Fe was identified in the ordered intermetallic fct-PtFe catalyst, indicating a lesser retention of Fe that causes the destruction of ordered structure and gives rise to poor durability. The enhancement in the durability of the ordered intermetallic fct-PtFeCu catalyst is ascribed to

  4. ADSORPSI ION CU(II MENGGUNAKAN PASIR LAUT TERAKTIVASI H2SO4 DAN TERSALUT Fe2O3

    Directory of Open Access Journals (Sweden)

    DS Pambudi

    2014-11-01

    Full Text Available Pasir laut merupakan bahan alam yang melimpah. Selain digunakan sebagai bahan bangunan, pasir dapat dimanfaatkan sebagai penjerap ion logam berat mengingat 30% lebih dari volumenya adalah pori-pori. Tujuan penelitian adalah untuk mengetahui kapasitas adsorpsi ion logam Cu(II menggunakan pasir laut kontrol, pasir laut teraktivasi H2SO4, pasir laut tersalut Fe2O3, serta pasir laut teraktivasi H2SO4 dan tersalut Fe2O3. Ada dua macam pasir laut yang digunakan, yaitu pasir hitam dan pasir putih. Kajian yang dilakukan meliputi optimasi adsorben pada variasi pH, konsentrasi ion logam, dan waktu kontak. Optimasi pH diperoleh pada pH 7, optimasi konsentasi ion logam diperoleh 250 ppm untuk pasir hitam dan 200 ppm untuk pasir putih, dan optimasi waktu diperoleh 60 menit untuk pasir hitam dan 90 menit untuk pasir putih. Kapasitas adsorpsi pasir laut teraktivasi H2SO4 dan tersalut Fe2O3 dalam menyerap ion logam tembaga sebesar 24,8634 mg/g untuk pasir hitam dan 19,8854 mg/g untuk pasir putih. Sebanyak 6,5 g pasir hitam teraktivasi H2SO4 dan tersalut Fe2O3 digunakan untuk menyerap limbah pada konsentrasi Cu(II sebesar 2960,32 ppm dengan persentase teradsorpsi sebesar 94,70%. Sedangkan pada pasir putih teraktivasi H2SO4 dan tersalut Fe2O3, sebanyak 8 g pasir digunakan untuk menyerap limbah dengan konsentrasi Cu(II sebesar 2984,13 ppm, hasilnya menunjukkan 92,56% ion logam Cu(II teradsorp. Sea sand is abundant natural materials. In addition to be used as a building material, sand can be utilized as heavy metal ion adsorbent, because it has quite a lot of pores, i.e 30% more than its volume. The purpose of this study was to determine the adsorption capacity of Cu(II ions using sea sand alone as control, H2SO4-activated sea sand, Fe2O3-coated sea sand, as well as H2SO4-activated and Fe2O3-coated sea sand. Two kinds of sea sand have been used in the research, i.e the black sand and the white sand. Studies were performed to examine the optimization of the

  5. Statistical theory of diffusion in concentrated bcc and fcc alloys and concentration dependencies of diffusion coefficients in bcc alloys FeCu, FeMn, FeNi, and FeCr

    Energy Technology Data Exchange (ETDEWEB)

    Vaks, V. G.; Khromov, K. Yu., E-mail: khromov-ky@nrcki.ru; Pankratov, I. R. [National Research Center “Kurchatov Institute,” (Russian Federation); Popov, V. V. [Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation)

    2016-07-15

    The statistical theory of diffusion in concentrated bcc and fcc alloys with arbitrary pairwise interatomic interactions based on the master equation approach is developed. Vacancy–atom correlations are described using both the second-shell-jump and the nearest-neighbor-jump approximations which are shown to be usually sufficiently accurate. General expressions for Onsager coefficients in terms of microscopic interatomic interactions and some statistical averages are given. Both the analytical kinetic mean-field and the Monte Carlo methods for finding these averages are described. The theory developed is used to describe sharp concentration dependencies of diffusion coefficients in several iron-based alloy systems. For the bcc alloys FeCu, FeMn, and FeNi, we predict the notable increase of the iron self-diffusion coefficient with solute concentration c, up to several times, even though values of c possible for these alloys do not exceed some percent. For the bcc alloys FeCr at high temperatures T ≳ 1400 K, we show that the very strong and peculiar concentration dependencies of both tracer and chemical diffusion coefficients observed in these alloys can be naturally explained by the theory, without invoking exotic models discussed earlier.

  6. CoFeCu electroplated nanowire arrays: Role of composition and annealing on structure and magnetic properties

    OpenAIRE

    Bran, Cristina; Palmero, Ester M.; Real, Rafael P. del; Vázquez Villalabeitia, Manuel

    2014-01-01

    CoxFe100-x and CoxFe95-xCu 5, with 30 < x < 90, arrays of nanowire, around 20 nm in diameter and about 5 μm long, have been prepared by electrodeposition filling the self-assembled nanopores of anodic alumina templates. These samples were later thermally annealed for 2 h in the range of temperatures up to 600 °C. Crystalline anisotropy was confirmed to exhibit bcc cubic structure with [110] texture in as-prepared state. First structural changes are observed after annealing at 450 °C when a re...

  7. First-principles investigation of local structure deformation induced by x-ray irradiation in κ -(BEDT-TTF ) 2Cu [N (CN) 2 ] Br

    Science.gov (United States)

    Kang, Lijing; Akagi, Kazuto; Hayashi, Kouichi; Sasaki, Takahiko

    2017-06-01

    We investigated the local structure deformation induced by x-ray irradiation in an organic molecular conductor κ -(BEDT-TTF ) 2Cu [N (CN) 2 ] Br using density-functional-theory (DFT-) based first-principles calculations. Our results demonstrate that the structure change due to x-ray excitation can be predicted by introducing a core hole at specific light atoms of the anion molecules with an infinite lifetime. The formation of a bond-shifted structure triggered by a double excitation was expected as a possible irreversible molecular defect leading to permanent irradiation damage. The calculated change in molecular vibration spectra after irradiation was consistent with the experimental results, and some different vibration modes by further irradiation were also predicted. The calculated local density of states indicates that the bond-shifted structure in the anion layer causes local potential modulation to the carriers (holes) in the cation layer. The introduced potential disorder for the carriers could increase the resistivity due to a localization effect that has been observed experimentally so far.

  8. Frustration and Dzyaloshinsky-Moriya anisotropy in the kagome francisites Cu3Bi (SeO3)2 O2X (X = Br , Cl )

    Science.gov (United States)

    Rousochatzakis, Ioannis; Richter, Johannes; Zinke, Ronald; Tsirlin, Alexander A.

    2015-01-01

    We investigate the antiferromagnetic canting instability of the spin-1/2 kagome ferromagnet, as realized in the layered cuprates Cu3Bi (SeO3)2 O2X (X = Br , Cl ). While the local canting can be explained in terms of competing exchange interactions, the direction of the ferrimagnetic order parameter fluctuates strongly even at short distances on account of frustration which gives rise to an infinite ground state degeneracy at the classical level. In analogy with the kagome antiferromagnet, the accidental degeneracy is fully lifted only by nonlinear 1 /S corrections, rendering the selected uniform canted phase very fragile even for spins-1/2, as shown explicitly by coupled-cluster calculations. To account for the observed ordering, we show that the minimal description of these systems must include the microscopic Dzyaloshinsky-Moriya interactions, which we obtain from density-functional band-structure calculations. The model explains all qualitative properties of the kagome francisites, including the detailed nature of the ground state and the anisotropic response under a magnetic field. The predicted magnon excitation spectrum and quantitative features of the magnetization process call for further experimental investigations of these compounds.

  9. Novel approach for removing brominated flame retardant from aquatic environments using Cu/Fe-based metal-organic frameworks: A case of hexabromocyclododecane (HBCD).

    Science.gov (United States)

    Li, Xiang; Liu, Hongli; Jia, Xiaoshan; Li, Guiying; An, Taicheng; Gao, Yanpeng

    2017-10-17

    Cu and Fe based metal-organic frameworks (Cu-BTC and Fe-BTC) were synthesized via a simple solvothermal method and innovatively utilized to remove a typical nonionic brominated flame retardant, hexabromocyclododecane (HBCD), from aquatic environment. Results show that over 80% of HBCD was removed by Cu-BTC within 5h, which is 1.3 times higher than removal by Fe-BTC. Thermodynamic analysis confirms spontaneous adsorption of HBCD onto the metal-organic frameworks (MOFs). Furthermore, the Gibbs free energy of Cu-BTC (-9.11kJ/mol) is more negative than that of Fe-BTC (-5.04kJ/mol). Both adsorption isotherms of HBCD onto Cu-BTC and Fe-BTC followed the Langmuir model, indicating a typical monomolecular-layer adsorption mechanism. In addition, the water stability test of these MOFs shows that the collapse of the Cu-BTC crystal structure is significantly hindered in the aquatic environment due to adsorption of the hydrophobic HBCD. The proposed adsorption mechanism includes van der Waals and hydrophobic interactions. These findings demonstrate that Cu/Fe-BTC are promising adsorbents for the removal of hydrophobic organic pollutants from aquatic environments, and may further improve the understanding of MOF materials for environmental applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Crystalline structure, magnetic and magnetoelastic properties of Nd6Fe13-xCoxCu intermetallic compounds

    Directory of Open Access Journals (Sweden)

    P Iranmanesh

    2011-03-01

    Full Text Available Influence of the partial substitution of Co for Fe on the structural, magnetic and magnetoelastic properties of Nd6Fe13Cu compounds are investigated. Analysis of X-ray diffraction patterns indicates that the multi-phase sample is formed for all samples. Upon Co substitution, the second phase Nd2Fe17, Nd2Fe17-yCoy with 0 < y < 1 and Nd2Fe17-zCoz with 1 < z < 2 is formed in the samples with x = 0, 1, 2, respectively so that the lattice parameters are decreased and the Curie temperature is increased. Due to the ferromagnetic phase Nd2Fe17-yCoy in sample with x = 1, the change of the anisotropy and increase of exchange effects are observed. The effects of long-range magnetic ordering processes on Néel temperature clearly appear in the temperature dependence of the spontaneous magnetostriction. Longitudinal (λl and transverse (λt magnetostrictions are measured to study the magnetoelastic behaviour of these compounds using a strain gauge method. In the low field region, magnetostrictive strains are small and then increase with increasing fields. Strong pining center of Nd atoms that creates large magnetocrystalline anisotropy prevents easy movement of domain walls. In the sample with x = 0, the magnetostriction contribution from the rare earth sublattice (Nd dominates at low temperature and the Fe sublattice contribution becomes increasingly important as temperature rises.

  11. On the Path to Optimizing the Al-Co-Cr-Cu-Fe-Ni-Ti High Entropy Alloy Family for High Temperature Applications

    Directory of Open Access Journals (Sweden)

    Anna M. Manzoni

    2016-03-01

    Full Text Available The most commonly investigated high entropy alloy, AlCoCrCuFeNi, has been chosen for optimization of its microstructural and mechanical properties by means of compositional changes and heat treatments. Among the different available optimization paths, the decrease of segregating element Cu, the increase of oxidation protective elements Al and Cr and the approach towards a γ-γ′ microstructure like in Ni-based superalloys have been probed and compared. Microscopical observations have been made for every optimization step. Vickers microhardness measurements and/or tensile/compression test have been carried out when the alloy was appropriate. Five derived alloys AlCoCrFeNi, Al23Co15Cr23Cu8Fe15Ni16, Al8Co17Cr17Cu8Fe17Ni33, Al8Co17Cr14Cu8Fe17Ni34.8Mo0.1Ti1W0.1 and Al10Co25Cr8Fe15Ni36Ti6 (all at.% have been compared to the original AlCoCrCuFeNi and the most promising one has been selected for further investigation.

  12. Effect of crystalline electric field on heat capacity of LnBaCuFeO5 (Ln = Gd, Ho, Yb)

    Science.gov (United States)

    Lal, Surender; Mukherjee, K.; Yadav, C. S.

    2018-02-01

    Structural, magnetic and thermodynamic properties of layered perovskite compounds LnBaCuFeO5 (Ln = Ho, Gd, Yb) have been investigated. Unlike the iso-structural compound YBaCuFeO5, which shows commensurate antiferromagnetic to incommensurate antiferromagnetic ordering below ∼200 K, the studied compounds do not show any magnetic transition in measured temperature range of 2-350 K. The high temperature heat capacity of the compounds is understood by employing contributions from both optical and acoustic phonons. At low temperature, the observed upturn in the heat capacity is attributed to the Schottky anomaly. The magnetic field dependent heat capacity shows the variation in position of the anomaly with temperature, which appears due to the removal of ground state degeneracy of the rare earth ions, by the crystalline electric field.

  13. Activation of Al-Cu-Fe quasicrystalline surface: fabrication of a fine nanocomposite layer with high catalytic performance

    Science.gov (United States)

    Kameoka, Satoshi; Tanabe, Toyokazu; Satoh, Futami; Terauchi, Masami; Tsai, An Pang

    2014-02-01

    A fine layered nanocomposite with a total thickness of about 200 nm was formed on the surface of an Al63Cu25Fe12 quasicrystal (QC). The nanocomposite was found to exhibit high catalytic performance for steam reforming of methanol. The nanocomposite was formed by a self-assembly process, by leaching the Al-Cu-Fe QC using a 5 wt% Na2CO3 aqueous solution followed by calcination in air at 873 K. The quasiperiodic nature of the QC played an important role in the formation of such a structure. Its high catalytic activity originated from the presence of highly dispersed copper and iron species, which also suppressed the sintering of nanoparticles.

  14. Effect of calcination temperature on microstructural and magnetic properties of CuFe2O4 spinel

    Energy Technology Data Exchange (ETDEWEB)

    Costa, A.F.; Melo, D.M.A.; Gomes, D.K.S.; Araujo, J.H.; Lima, A.C. [Universidade Federal do Rio Grande do Norte (UFRN), RN (Brazil); Pimentel, P.M. [Universidade Federal Rural do Semi-Arido (UFERSA), Mossoro, RN (Brazil); Santana, R.S.; Oliveira, R.M.P.B. [Universidade Federal de Sergipe (UFS), SE (Brazil)

    2014-07-01

    In this research, we report a study of nanostructured CuFe{sub 2}O{sub 4} Spinel obtained by a method which makes uses of gelatin as an organic precursor. The structural and magnetic properties were investigated in function of calcination temperature. The precursor powders were calcined at 700 and 900 deg C to obtain spinel phase. Then were characterized using X-ray diffraction combined with the Rietveld refinement method, infrared spectroscopy (FTIR), and magnetic measurements. The X-ray diffraction patterns revealed the presence of an inverse spinel phase, corresponding to copper ferrite in all samples. Moreover, Fe{sub 2}O{sub 3} and CuO phases were also identified. The results reveal that the calcination temperature strongly influences the magnetic properties of the prepared oxides. (author)

  15. Investigation of the Enthalpy/Entropy Variation and Structure of Cu-Al-Mn-Fe Shape Memory Alloys

    Science.gov (United States)

    Canbay, C. Aksu; Gudeloglu, S.; Genc, Z. Karagoz

    2015-04-01

    Cu-based Cu-Al-Mn-Fe shape memory alloys were produced in an arc melter under vacuum. The crystal structure of the fabricated alloys were determined by means of X-ray diffraction (XRD). The XRD analysis results indicated that the martensitic phase of the samples have an M18R structure. The characteristic transformation temperatures, thermodynamic parameters, and the activation energy values of the samples according to Kissinger and Ozawa methods were determined by differential scanning calorimetry measurements. The austenite transformation temperatures of the samples were found as , respectively. Also, the calculated activation energy values of the samples according to Kissinger and Ozawa methods are compared with each other. The effect of the presence of Al and Fe in the samples on the thermodynamic parameters is studied in this work.

  16. Moessbauer study of Cu sub 0 sub . sub 8 Fe sub 2 sub . sub 2 O sub 4

    CERN Document Server

    Kim, S J; An, D H; Kang, K U; Baek, K S; Oak, H N

    2000-01-01

    Cu sub 0 sub . sub 8 Fe sub 2 sub . sub 2 O sub 4 has been studied by using Moessbauer spectroscopy and X-ray diffraction. The crystal is found to have a cubic spinel structure with the lattice constant a sub 0 =8.399 +- 0.005 A. It is noteworthy that a 20% replacement of Cu by Fe in the copper ferrite transforms the crystal structure from tetragonal to cubic and decreases the quadrupole shifts drastically. The iron ions at both A (tetrahedral) and B (octahedral) sites are found to be in ferric states. Atomic migration between A- and B-sites starts near 300 K and increases rapidly with increasing temperature to such a degree that 78% of the ferric ions at the A-sites move over to the B sites at 600 K.

  17. Current induced magnetization switching in Co/Cu/Ni-Fe nanopillar with orange peel coupling

    Directory of Open Access Journals (Sweden)

    D. Aravinthan

    2015-07-01

    Full Text Available The impact of orange peel coupling on spin current induced magnetization switching in a Co/Cu/Ni-Fe nanopillar device is investigated by solving the switching dynamics of magnetization of the free layer governed by the Landau-Lifshitz-Gilbert-Slonczewski (LLGS equation. The value of the critical current required to initiate the magnetization switching is calculated analytically by solving the LLGS equation and verified the same through numerical analysis. Results of numerical simulation of the LLGS equation using Runge-Kutta fourth order procedure shows that the presence of orange peel coupling between the spacer and the ferromagnetic layers reduces the switching time of the nanopillar device from 67 ps to 48 ps for an applied current density of 4 × 1012Am−2. Also, the presence of orange peel coupling reduces the critical current required to initiate switching, and in this case, from 1.65 × 1012Am−2 to 1.39 × 1012Am−2.

  18. Current induced magnetization switching in Co/Cu/Ni-Fe nanopillar with orange peel coupling

    Energy Technology Data Exchange (ETDEWEB)

    Aravinthan, D.; Daniel, M. [Centre for Nonlinear Dynamics, School of Physics, Bharathidasan University, Tiruchirappalli - 620 024 (India); Sabareesan, P. [Centre for Nonlinear Science and Engineering, School of Electrical and Electronics Engineering, SASTRA University, Thanjavur - 613 401 (India)

    2015-07-15

    The impact of orange peel coupling on spin current induced magnetization switching in a Co/Cu/Ni-Fe nanopillar device is investigated by solving the switching dynamics of magnetization of the free layer governed by the Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation. The value of the critical current required to initiate the magnetization switching is calculated analytically by solving the LLGS equation and verified the same through numerical analysis. Results of numerical simulation of the LLGS equation using Runge-Kutta fourth order procedure shows that the presence of orange peel coupling between the spacer and the ferromagnetic layers reduces the switching time of the nanopillar device from 67 ps to 48 ps for an applied current density of 4 × 10{sup 12}Am{sup −2}. Also, the presence of orange peel coupling reduces the critical current required to initiate switching, and in this case, from 1.65 × 10{sup 12}Am{sup −2} to 1.39 × 10{sup 12}Am{sup −2}.

  19. Field-induced Incommensurate Lattice Modulations in the Delafossite CuFeO2

    Science.gov (United States)

    Terada, Noriki; Mitsuda, Setsuo; Tanaka, Yoshikazu; Tabata, Yoshikazu; Katsumata, Koichi; Kikkawa, Akiko

    2008-05-01

    The results of synchrotron X-ray diffraction measurements on a single crystal of the triangular lattice antiferromagnet CuFeO2 under zero and non-zero applied magnetic fields are reported. We find four satellite reflections at (0, 3+q, 1/2), (0, 4-q, 1/2), (0, 4-2q, 0), and (0, 3+2q, 0) with the incommensurate wave number q ˜ 0.415 in the ferroelectric incommensurate (FEIC) phase which appears in the magnetic field, H, between 7 and 13 T at low temperatures. In the partially disordered (PD) phase which exists in the temperature, T, range between 11 and 14 K, we find two satellite reflections at (0, 4-q, 1/2) and (0, 4-2q, 0) with the incommensurate wave number q ˜ 0.4. The T and H dependence of these satellite reflections are studied. We interpret that the reflections observed in the FEIC phase arise from incommensurate lattice modulations caused by a magnetoelastic coupling with the underlying magnetic structure. The observation of the reflection (0, 4-q, 1/2) in finite fields and the (0, 4-2q, 0) reflection at 0≤ H in the PD phase is also explained by the same model. A calculation of the X-ray diffraction intensity assuming the displacement of oxygen ions only successfully explains the observation. We discuss the relevance of these satellite reflections to the ferroelectricity.

  20. Determination of Cu, Pb, Fe, and Zn in plant component polymers of a hyperaccumulating plant.

    Science.gov (United States)

    Kobayashi, Fumihisa; Maki, Teruya; Nakamura, Yoshitoshi; Ueda, Kazumasa

    2005-12-01

    Phytoremediation is an innovative technology that utilizes the natural properties of plants to remediate hazardous waste sites. For more cost-effective phytoremediation, it is important to utilize a hyperaccumulating plant after phytoremediation, i.e. the recovery of valuable metals and the production of useful materials. In this work, the determination of metals in plant component polymers in a fern, Athyrium yokoscense, as a hyper-accumulating plant was established using steam explosion, Wayman's extraction method, and ICP emission spectrometry. After A. yokoscense plants were treated by steam explosion, the steam-exploded A. yokoscense were separated into four plant component polymers, ie. water-soluble material fraction, holocellulose fraction, methanol-soluble lignin fraction, and residual lignin fraction. The concentrations of Cu, Pb, Fe, and Zn in these plant component polymers and the dry weights of plant component polymers were measured. These analytical process determining metals in the plants will contribute to not only the evaluation and the efforts of phytoremediation using a hyperaccumulating plant, but also to the development of more effective phytoremediation.

  1. Self-lubricating tribological characterization of lead free Fe-Cu based plain bearing material

    Directory of Open Access Journals (Sweden)

    Shuhaib Mushtaq

    2017-03-01

    Full Text Available The negative impact of lead on environment and thereby its reciprocity on the health of mankind, there is a growing emphasis on resisting the usage of lead in bearings. Owing to this, new bearing materials that provide comparable tribological performance to that of lead containing alloys are being developed. In this study, lead free Fe-Cu based powders with addition of elements such as tin, molybdenum disulfide and Nano boron nitride (BN have been developed by powder metallurgy (PM technique in order to improve the tribological and mechanical properties. The powder mixtures were compressed at a pressure of 500 MPa, and then sintered in dry hydrogen atmosphere at 9000C for 50 minutes. The mechanical and tribological properties obtained due to addition of the said elements is presented in this study. The tribological behavior of the selected alloys is analyzed by reciprocating-sliding tests under dry conditions. The morphology of wear scars and the microstructure of the wear surfaces were investigated. The material with 2.5 wt.% of Sn exhibited the highest value of hardness, the material with 7.5 wt.% of Nano BN comparably shows the low coefficient of friction and wear rate as compared with 5 wt.% of Nano BN.

  2. Tribology and surface topography of Al-10Cu-Fe alloy produced by rheocasting process

    Science.gov (United States)

    Sankara Rao, L.; Jha, A. K.; Ojha, S. N.

    2017-09-01

    In the present investigation, Al-10Cu-Fe alloys were produced by rheocasting process at different mechanical stirring speeds. These castings were poured into a metallic mould at a temperature of 620 °C i.e. in the semi-solid state. The resultant microstructures and wear properties were compared with a conventional metal mould cast alloy. The rheocast alloys have shown better mechanical (ultimate tensile strength and hardness) and wear properties as compared to metal mould cast alloy. Moreover, rheocast alloy which was produced at 1200 rpm stirring speed exhibited enhanced wear and mechanical properties as compared to other rheocast alloys. The improved wear rate for this alloy may be attributed to finer grain size and the nearly-spherical morphology of the primary α-phase. The metal mould cast and rheocast alloy at 400 rpm have shown adhesive wear. Whereas, other rheocast alloys have displayed microcutting abrasion. The noticeable decrease in the average roughness for 3 m s-1 sliding velocity was observed as compared to the 1 m s-1. In addition, the average roughness value of the 1200 rpm stirred alloy is lower than that of the alloy produced at 800 rpm stirring speed.

  3. Effect of Cu on the evolution of precipitation in an Fe-Cr-Ni-Al-Ti maraging steel

    Energy Technology Data Exchange (ETDEWEB)

    Schnitzer, Ronald, E-mail: ronald.schnitzer@unileoben.ac.at [Christian Doppler Laboratory for Early Stages of Precipitation, University of Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Schober, Michael [Department of Physical Metallurgy and Materials Testing, University of Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Zinner, Silvia [Boehler Edelstahl GmbH and Co KG, Mariazeller Strasse 25, A-8605 Kapfenberg (Austria); Leitner, Harald [Christian Doppler Laboratory for Early Stages of Precipitation, University of Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria)] [Department of Physical Metallurgy and Materials Testing, University of Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria)

    2010-06-15

    The evolution of precipitates in an Fe-Cr-Ni-Al-Ti stainless maraging steel alloyed with Cu was investigated during aging at 525 deg. C. Atom probe tomography was used to reveal the development of precipitates and to determine their chemical composition. Two types of precipitates were observed to form during the aging process. Based on their chemical composition these are assumed to be NiAl B2 and Ni{sub 3}(Ti,Al) ({eta}-phase). The two phases of precipitates were found to develop independently of each other and the addition of Cu was found to accelerate precipitation. However, the effect of Cu on the nucleation of these phases is different: on the one hand, in the case of NiAl, Cu is incorporated and thus reduces the activation energy by reducing the lattice misfit; on the other hand, Cu acts as a nucleation site for the precipitation of Ni{sub 3}(Ti,Al) by forming independent Cu clusters.

  4. Production of sulfate radical from peroxymonosulfate induced by a magnetically separable CuFe2O4 spinel in water: Efficiency, stability, and mechanism

    KAUST Repository

    Zhang, Tao

    2013-03-19

    A simple, nonhazardous, efficient and low energy-consuming process is desirable to generate powerful radicals from peroxymonosulfate (PMS) for recalcitrant pollutant removal. In this work, the production of radical species from PMS induced by a magnetic CuFe2O4 spinel was studied. Iopromide, a recalcitrant model pollutant, was used to investigate the efficiency of this process. CuFe2O4 showed higher activity and 30 times lower Cu2+ leaching (1.5 μg L-1 per 100 mg L-1) than a well-crystallized CuO at the same dosage. CuFe 2O4 maintained its activity and crystallinity during repeated batch experiments. In comparison, the activity of CuO declined significantly, which was ascribed to the deterioration in its degree of crystallinity. The efficiency of the PMS/CuFe2O4 was highest at neutral pH and decreased at acidic and alkaline pHs. Sulfate radical was the primary radical species responsible for the iopromide degradation. On the basis of the stoichiometry of oxalate degradation in the PMS/CuFe 2O4, the radical production yield from PMS was determined to be near 1 mol/mol. The PMS decomposition involved an inner-sphere complexation with the oxide\\'s surface Cu(II) sites. In situ characterization of the oxide surface with ATR-FTIR and Raman during the PMS decomposition suggested that surface Cu(II)-Cu(III)-Cu(II) redox cycle was responsible for the efficient sulfate radical generation from PMS. © 2013 American Chemical Society.

  5. Teores de Fe, Mn, Zn, Cu, Ni E Co em solos de referência de Pernambuco

    Directory of Open Access Journals (Sweden)

    Caroline Miranda Biondi

    2011-06-01

    Full Text Available Metais pesados formam um grupo de elementos com particularidades relevantes e de ocorrência natural no ambiente, como elementos acessórios na constituição de rochas. Esses elementos, apesar de associados à toxidez, exigem tratamento diferenciado em relação aos xenobióticos, uma vez que diversos metais possuem essencialidade (Fe, Mn, Cu, Zn e Ni e benefício (Co comprovados para as plantas. Nesse contexto, o objetivo deste trabalho foi determinar os teores naturais dos metais Fe, Mn, Zn, Ni, Cu e Co nos solos de referência de Pernambuco. Foram coletadas amostras de solo nas três regiões fisiográficas (Zona da Mata, Agreste e Sertão, dos dois primeiros horizontes dos 35 solos de referência do Estado de Pernambuco. A digestão das amostras baseou-se no método 3051A (USEPA, 1998, e a determinação foi efetuada em ICP-OES. Correlações significativas foram estabelecidas entre os metais e entre estes e a fração argila do solo, em ambos os horizontes, indicando a associação comum da maioria dos metais com solos mais argilosos. A maioria dos solos apresentou teores de Fe, Mn, Zn, Cu, Ni e Co menores que os de solos de outras regiões do País, com litologia mais máfica, o que corrobora o fato de que os teores desses elementos são mais diretamente relacionados aos minerais Fe-magnesianos. Os resultados indicam baixo potencial dos solos de Pernambuco em liberar Cu, Co e Ni para plantas, enquanto deficiências de Zn, Fe e Mn são menos prováveis. Os teores naturais de Fe, Mn, Zn, Cu, Ni e Co determinados podem ser utilizados como base para definição dos Valores de Referência de Qualidade para os solos de Pernambuco, de acordo com o preconizado pela legislação nacional.

  6. The distribution of four trace elements (Fe, Mn, Cu, Zn in forage and the relation to scrapie in Iceland

    Directory of Open Access Journals (Sweden)

    Jóhannesson Torkell

    2010-05-01

    Full Text Available Abstract Background Previous studies indicated that the iron (Fe/manganese (Mn ratio in forage of sheep was significantly higher on scrapie-afflicted farms than on farms in other scrapie categories. This study was conducted to examine whether Fe and Mn in forage of sheep varied in general according to the scrapie status of different areas in the country. Copper (Cu and zinc (Zn were also included because of a possible relation to scrapie. Methods The country was subdivided into seven Areas (I-VII. Three Areas (I, IV, VII were designated scrapie-free (never diagnosed or eradicated and three as scrapie-endemic (II, III, VI; status of Area V was taken as unsettled. Of the harvest 2007 1552 samples were analysed from 344 farms all over the country, mostly grass silage from plastic bales (>90% and from the first cut (70% or more. Results were expressed as mg kg-1 dry matter. Results Fe varied enormously from less than 100 mg kg-1 to 5000 mg kg-1. Mn varied nearly thirtyfold (17-470 mg kg-1. Fe concentration was significantly lower in Area I than in Areas II, V and VI. Mn concentration was significantly higher in Areas I, IV and VII than in Areas II, III, V and VI. The Fe/Mn ratio was significantly less in Area I than in the other areas (except Area IV. Mean Cu concentration was 6.6-8.3 mg kg-1 and the mean Zn concentration was 24-29 mg kg-1. They differed significantly in some areas. Conclusions 1 Fe tended to be in lower amounts in sheep forage in scrapie-free than in endemic areas; 2 Mn was in higher amounts in forage in scrapie-free than endemic areas; 3 the Fe/Mn ratio was lower in scrapie-free than in endemic areas; 4 the Fe/Mn ratio may possibly be used as an indicator of scrapie status; 5 Cu and Zn in sheep forage were not related to scrapie; 6 further study on the role of Fe and Mn in the occurrence of scrapie in Iceland is needed.

  7. Long-range magnetic order and spin-lattice coupling in the delafossite CuFeO2

    OpenAIRE

    Eyert, Volker; Fresard, Raymond; Maignan, Antoine

    2008-01-01

    The electronic and magnetic properties of the delafossite CuFeO2 are investigated by means of electronic structure calculations. They are performed using density functional theory in the generalized gradient approximation as well as the new full-potential augmented spherical wave method. The calculations reveal three different spin states at the iron sites. Taking into account the correct crystal structure, we find long-range antiferromagnetic ordering in agreement with experiment. Contrastin...

  8. Investigation into nanoscratching mechanical response of AlCrCuFeNi high-entropy alloys using atomic simulations

    Science.gov (United States)

    Wang, Zining; Li, Jia; Fang, QiHong; Liu, Bin; Zhang, Liangchi

    2017-09-01

    The mechanical behaviors and deformation mechanisms of scratched AlCrCuFeNi high entropy alloys (HEAs) have been studied by molecular dynamics (MD) simulations, in terms of the scratching forces, atomic strain, atomic displacement, microstructural evolution and dislocation density. The results show that the larger tangential and normal forces and higher friction coefficient take place in AlCrCuFeNi HEA due to its outstanding strength and hardness, and high adhesion and fracture toughness over the pure metal materials. Moreover, the stacking fault energy (SFE) in HEA increases the probability to initiate dislocation and twinning, which is conducive to the formation of complex deformation modes. Compared to the single element metal workpieces, the segregation potency of solutes into twinning boundary (TB) is raised due to the decreasing segregation energy of TB, resulting in the stronger solute effects on improving twinning properties for HEA workpiece. The higher dislocation density and the more activated slipping planes lead to the outstanding plasticity of AlCrCuFeNi HEA. The solute atoms as barriers to hinder the motion of dislocation and the severe lattice distortion to suppress the free slipping of dislocation are significantly stronger obstacles to strengthen HEA. The excellent comprehensive scratching properties of the bulk AlCrCuFeNi HEAs are associated with the combined effects of multiple strengthening mechanisms, such as dislocation strengthening, deformation twinning strengthening as well as solute strengthening. This work provides a basis for further understanding and tailoring SFE in mechanical properties and deformation mechanism of HEAs, which maybe facilitate the design and preparation of new HEAs with high performance.

  9. Analysis of Relations Between the Level of Mg, Zn, Ca, Cu, and Fe and Depressiveness in Postmenopausal Women.

    Science.gov (United States)

    Szkup, Małgorzata; Jurczak, Anna; Brodowska, Aleksandra; Brodowska, Agnieszka; Noceń, Iwona; Chlubek, Dariusz; Laszczyńska, Maria; Karakiewicz, Beata; Grochans, Elżbieta

    2017-03-01

    Numerous observations suggest a possible connection between the levels of Mg, Zn, Fe, and Zn and the incidence of depressive symptoms. Depression is two to three times more common in women than in men. The menopausal period is extremely conducive to depressive disorders. The aim of this study was to assess the severity of depressive symptoms in postmenopausal women depending on the levels of Mg, Zn, Ca, Cu, and Fe. The study included 198 healthy postmenopausal women at the average age of 56.26 ± 5.55 years. In the first part of the study, standardized research tools were used, namely the Primary Care Evaluation of Mental Disorders (PRIME-MD) and the Beck Depression Inventory (BDI). The second part involved biochemical analysis of Mg, Zn, Ca, Cu, and Fe levels in blood serum. The lowest Cu levels were observed in women without depressive symptoms (1.07 ± 0.22 mg/l) and the highest in those with severe depressive symptoms (1.19 ± 0.17 mg/l), (p ≤ 0.05). The lowest Mg levels were observed in women with depressive symptoms (14.28 ± 2.13 mg/l), and the highest in women without depressive symptoms (16.30 ± 3.51 mg/l), (p ≤ 0.05). The average serum Mg levels (15.75 ± 3.23 mg/l) decreased compared to the reference values (18.77-24 mg/l). What is striking is a potential relation between the levels of Mg and Cu and depressiveness. Our results indicate to a higher vulnerability to depression in a group of women with lower levels of Mg and higher levels of Cu.

  10. Influence of Magnetic Field on the Mesoporous Structure of Fe-Cu Compounds in Dye-Sensitized Photovoltaic Cells

    Science.gov (United States)

    Alami, Abdul Hai; Zhang, Di; Aokal, Camilia; Abed, Jehad; Abdoun, Ideisan Abu; Alawadhi, Hussain

    2016-03-01

    This paper investigates the effect of applying static and dynamic magnetic fields on the deposition of Fe-Cu compound on the working electrode of a dye-sensitized solar cell. The deposition of this compound on glass is complicated due to the fact that it cannot be evaporated or sintered beyond the dissociation temperature of 973 K (700 °C), and the doctor blade technique causes detrimental layer inconsistencies. The Fe-Cu compound is relatively easy to produce and is significantly cheaper and more absorptive (>81 pct) in the Vis-NIR than the standard TiO2 mesoporous material used for solar cells. It also behaves as a semiconductor due to the high diffusion of the Fe into the Cu lattice that a bandgap of 1.8 eV is obtained. The use of a Schiff base dye with a compatible bandgap of 1.68 eV is used as a sensitizer for the production of a test cell that generated more photocurrent than its TiO2 counterpart, which is a promising result for an alternative mesoporous layer in solar cells.

  11. Electronic Structure and Thermoelectric Properties of the Delafossite-Type Oxides CuFe1- x Ni x O2

    Science.gov (United States)

    Nozaki, T.; Hayashi, K.; Kajitani, T.

    2009-07-01

    In this study, we investigated the chemical composition and electronic structure of the delafossite-type oxides CuFeO2 (CFO) and CuFe0.98Ni0.02O2 (CFNO). The hole carrier density in the Cu and FeO2 layers of CFNO was found to be different from that of CFO, leading to the enhancement of electrical conductivity by Ni substitution. In addition, thermoelectric properties were found to be affected by the surface treatment, possibly due to some surface contamination. An etched CFNO (E-CFNO) exhibited a higher electrical conductivity and a higher Seebeck coefficient relative to the polished CFNO (P-CFNO). The thermal conductivity did not change much between E-CFNO and P-CFNO. As a result, the thermoelectric performance of E-CFNO was higher than that of P-CFNO. This result indicates that etching is needed when we use CFNO as a p-leg in thermoelectric generators.

  12. Structural and magnetic properties of epitaxial delafossite CuFeO2 thin films grown by pulsed laser deposition

    Science.gov (United States)

    Senty, Tess; Joshi, Toyanath; Trappen, Robbyn; Zhou, Jinling; Chen, Song; Ferrari, Piero; Borisov, Pavel; Song, Xueyan; Holcomb, Mikel; Bristow, Alan; Cabrera, Alejandro; Lederman, David

    2015-03-01

    Growth of pure phase delafossite CuFeO2 thin films on Al2O3 (00.1) substrates by pulsed laser deposition was systematically investigated as function of growth temperature and oxygen pressure. X-ray diffraction, transmission electron microscopy, Raman scattering, and x-ray absorption spectroscopy confirmed the existence of the delafossite phase. Infrared reflectivity spectra determined a band edge at 1.15 eV, in agreement with the bulk delafossite data. Magnetization measurements on CuFeO2 films demonstrated a phase transition at TC = 15K, which agrees with the first antiferromagnetic transition at 14K in the bulk CuFeO2. Low temperature magnetic phase is best described by commensurate, weak ferromagnetic spin ordering along the c-axis. This work was supported by a Research Challenge Grant from the West Virginia Higher Education Policy Commission (HEPC.dsr.12.29) and the Microelectronics Advanced Research Corporation (Contract #2013-MA-2382) at WVU. Work at PUC was supported by FONDECyT.

  13. Intrinsic Kinetics of Dimethyl Ether Synthesis from Plasma Activation of CO2 Hydrogenation over Cu-Fe-Ce/HZSM-5.

    Science.gov (United States)

    Su, Tongming; Zhou, Xinhui; Qin, Zuzeng; Ji, Hongbing

    2017-02-02

    CO2 is activated in a plasma reactor followed by hydrogenation over a Cu-Fe-Ce/HZSM-5 catalyst, and the intrinsic kinetics of the plasma catalytic process are studied. Compared with CO2 hydrogenation using Cu-Fe-Ce/HZSM-5 alone, the CO2 conversion and the dimethyl ether selectivity for the plasma catalytic process are increased by 16.3 %, and 10.1 %, respectively, indicating that the CO2 was activated by the plasma to promote hydrogenation. A study of the intrinsic kinetics shows that the activation energies of methanol formation, the reverse water-gas shift reaction, and methanol dehydration to dimethyl ether are 149.34, 75.47, and 73.18 kJ mol-1 , respectively, which are lower than if Cu-Fe-Ce/HZSM-5 is used without plasma, indicating that the activation of CO2 in the plasma reduces the activation energy of the hydrogenation reaction and improves the yield of dimethyl ether. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Electrical resistivity measurement of Fe-0.6%Cu alloy irradiated by neutrons at 14-19 K

    Science.gov (United States)

    Xu, Q.; Yokotani, T.; Sato, K.; Hori, F.

    2016-12-01

    Electrical resistivity measurement is a useful experimental method for investigating the recovery of defects that are induced by irradiation in metals and alloys. In this study, an Fe-0.6%Cu alloy, used to model steel from old commercial reactor pressure vessels, was irradiated by neutrons at a low temperature range of 14-19 K with a dose of about 1.3 × 1020 neutrons/m2 (E > 0.1 MeV) in the Kyoto University Reactor (KUR); electrical resistivity measurement was performed during irradiation and after annealing of the irradiated sample from 20 K to 300 K to investigate the migration of point defects in the Fe-0.6%Cu alloy. The electrical resistivity was measured at 14-19 K. With the increase in the irradiation dose, the electrical resistivity increased linearly. Four peaks appeared at 70 K, 100 K, 150 K, and 260 K, in the change of electrical resistivity during annealing of the irradiated sample up to 300 K. The former two peaks were caused by the recombination of interstitials and vacancies, and the latter two peaks were caused by the formation of interstitial clusters and the migration of vacancies. Compared with previous electron irradiation results, the former two peaks represent new data, as does the ratio of recombination caused by close-pair and correlation to that caused by migrations of mixed-interstitials Fe-Cu and vacancies decreased in neutron irradiation.

  15. Application of 57Fe Mössbauer spectroscopy as a tool for mining exploration of bornite (Cu5FeS4) copper ore

    Science.gov (United States)

    Gainov, R. R.; Vagizov, F. G.; Golovanevskiy, V. A.; Ksenofontov, V. A.; Klingelhöfer, G.; Klekovkina, V. V.; Shumilova, T. G.; Pen'kov, I. N.

    2014-04-01

    Nuclear resonance methods, including Mössbauer spectroscopy,are considered as unique techniques suitable for remote on-line mineralogical analysis. The employment of these methods provides potentially significant commercial benefits for mining industry. As applied to copper sulfide ores, Mössbauer spectroscopy method is suitable for the analysis noted. Bornite (formally Cu5FeS4) is a significant part of copper ore and identification of its properties is important for economic exploitation of commercial copper ore deposits. A series of natural bornite samples was studied by 57Fe Mössbauer spectroscopy. Two aspects were considered: reexamination of 57Fe Mössbauer properties of natural bornite samples and their stability irrespective of origin and potential use of miniaturized Mössbauer spectrometers MIMOS II for in-situ bornite identification. The results obtained show a number of potential benefits of introducing the available portative Mössbauer equipment into the mining industry for express mineralogical analysis. In addition, results of some preliminary 63,65Cu nuclear quadrupole resonance (NQR) studies of bornite are reported and their merits with Mössbauer techniques for bornite detection discussed.

  16. Nitrite to nitric oxide interconversion by heme FeII complex assisted by [CuI(tmpa)]+

    KAUST Repository

    Turias, Francesc

    2015-09-09

    The present computational study complements the recent experimental efforts by Karlin and coworkers to describe the interconversion of nitrite to nitric oxide by means of an iron porphyrin complex together with a Cu chemical system, i.e., the iron(II) complex (F8TPP)FeII [F8TPP = tetrakis(2,6-difluorophenyl)porphyrinate(2−)] and a preformed copper(II)–nitrito complex [(tmpa)CuII(NO2)][B(C6F5)4] [tmpa = tris(2-pyridylmethyl)amine], being the latter an oxidized species of [(tmpa)CuI(MeCN)]+. By DFT calculations, we unravel how the reduction of nitrite to nitric oxide takes place through a μ-oxo heme-FeIII–O–CuII complex, following a mimetic path as in the cytochrome c oxidase. Mayer bond order (MBO) and energy decomposition analyses are used to analyze the bonding strength of such nitro derivatives to either copper or iron. © 2015 Springer Science+Business Media New York

  17. Synthesis and characterization of the 1.1 adducts of copper(1) halides with bidentatate N,N-bis(benzophenone)-1,2-diiminoethane Schiff bases: Crystal structures of [Cu(bz2en)2][CuX2](X=Br,l) complexes

    NARCIS (Netherlands)

    Kia, Reza; Mirkhani, Valiollah; Harkema, Sybolt; van Hummel, G.J.

    2007-01-01

    1:1 adducts of N,N′-bis(benzophenone)-1,2-diiminoethane (bz2en) with copper(I) chloride, bromide and iodide, [Cu(bz2en)2][CuX2] (X = Cl, Br, and I), have been synthesized and the structures of the solid bromide and iodide adducts were determined by X-ray crystallography from single-crystal data. The

  18. Effect of Water Vapor During Secondary Cooling on Hot Shortness in Fe-Cu-Ni-Sn-Si Alloys

    Science.gov (United States)

    Sampson, Erica; Sridhar, Seetharaman

    2014-10-01

    Residual Cu in recycled steel scrap can cause hot shortness when the iron matrix is oxidized. Hot shortness can occur directly after the solid steel is formed from continuous casting as the steel undergoes a cooling process known as secondary cooling where water is first sprayed on the surface to promote cooling. This is followed by a radiant cooling stage where the steel is cooled in air to room temperature. This investigation examines the roles of water vapor, Si content, temperature, and the presence of Sn in a Fe-0.2 wt pct Cu-0.05 wt pct Ni alloy on oxidation, separated Cu and Cu induced-hot shortness during simulations of the secondary cooling process. The secondary cooling from 1473 K (1200 °C) resulted in a slight increase in liquid quantity and grain boundary penetration as compared to the isothermal heating cycles at 1423 K (1150 °C) due to the higher temperatures experienced in the non-isothermal cycle. The addition of water vapor increased the sample oxidation as compared to samples processed in dry atmospheres due to increased scale adherence, scale plasticity, and inward transport of oxygen. The increase in weight gain of the wet atmosphere increased the liquid formation at the interface in the non-Si containing alloys. The secondary cooling cycle with water vapor and the effect of Sn lead to the formation of many small pools of Cu-rich liquid embedded within the surface of the metal due to the Sn allowing for increased grain boundary decohesion and the water vapor allowing for oxidation within liquid-penetrated grain boundaries. The presence of Si increased the amount of occlusion of Cu and Fe, significantly decreasing the quantity of liquid at the interface and the amount of grain boundary penetration.

  19. Fabrication of Fe{sub 3}O{sub 4}@CuO core-shell from MOF based materials and its antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Rajabi, S.K. [Department of Chemistry, University of Guilan, University Campus 2, Rasht (Iran, Islamic Republic of); Sohrabnezhad, Sh., E-mail: sohrabnezhad@guilan.ac.ir [Department of Chemistry, Faculty of Science, University of Guilan, P.O. Box 1914, Rasht (Iran, Islamic Republic of); Ghafourian, S. [Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam (Iran, Islamic Republic of)

    2016-12-15

    Magnetic Fe{sub 3}O{sub 4}@CuO nanocomposite with a core/shell structure was successfully synthesized via direct calcinations of magnetic Fe{sub 3}O{sub 4}@HKUST-1 in air atmosphere. The morphology, structure, magnetic and porous properties of the as-synthesized nano composites were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and vibration sample magnetometer (VSM). The results showed that the nanocomposite material included a Fe{sub 3}O{sub 4} core and a CuO shell. The Fe{sub 3}O{sub 4}@CuO core-shell can be separated easily from the medium by a small magnet. The antibacterial activity of Fe{sub 3}O{sub 4}-CuO core-shell was investigated against gram-positive and gram-negative bacteria. A new mechanism was proposed for inactivation of bacteria over the prepared sample. It was demonstrated that the core-shell exhibit recyclable antibacterial activity, acting as an ideal long-acting antibacterial agent. - Graphical abstract: Fe{sub 3}O{sub 4}@CuO core-shell release of copper ions. These Cu{sup 2+} ions were responsible for the exhibited antibacterial activity. - Highlights: • The Fe{sub 3}O{sub 4}@CuO core-shell was prepared by MOF method. • This is the first study of antibacterial activity of core-shell consist of CuO and Fe{sub 3}O{sub 4}. • The core-shell can be reused effectively. • Core-shell was separated from the reaction solution by external magnetic field.

  20. Facile hydrothermal synthesis of CuFeO2 hexagonal platelets/rings and graphene composites as anode materials for lithium ion batteries.

    Science.gov (United States)

    Dong, Yucheng; Cao, Chenwei; Chui, Ying-San; Zapien, Juan Antonio

    2014-09-11

    Delafossite CuFeO2 hexagonal platelets/rings and graphene composites were synthesized by a low temperature hydrothermal method. The formation mechanism of CuFeO2 hexagonal platelets/rings follows the combined effects of both GO and NaOH. The obtained composites as anode materials display a good battery performance with high reversible capacity, good rate capability and cyclic stability.

  1. Magnetic core-shell CuFe2O4@C3N4 hybrids for visible light photocatalysis of Orange II.

    Science.gov (United States)

    Yao, Yunjin; Lu, Fang; Zhu, Yanping; Wei, Fengyu; Liu, Xueting; Lian, Chao; Wang, Shaobin

    2015-10-30

    Novel CuFe2O4@C3N4 core-shell photocatalysts were fabricated through a self-assembly method and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, transmission electron microscopy and Uv-vis diffuse reflection spectroscopy. The photocatalytic performances of the CuFe2O4@C3N4 catalysts were evaluated in photo Fenton-like discoloration of Orange II dye using H2O2 as an oxidant under visible-light irradiation (λ>420 nm). It was found the CuFe2O4@C3N4 hybrid (mass ratio of CuFe2O4/g-C3N4 at 2:1) exhibits a superior activity as compared with single component of CuFe2O4 or g-C3N4 and the mixture of g-C3N4 and CuFe2O4, due to the elevation of the separation efficiency of photoinduced electron-hole pairs, resulted from the heterojunction between the interfaces of g-C3N4 and CuFe2O4. The quenching tests of different scavengers displayed that O2(•-), OH and h(+) are responsible for the Orange II decolorization. In addition, the effects of initial concentration of the dye contaminant (0.014-0.140 mM), different anions (Cl(-), SO4(2-), NO3(-), CH3COO(-) and HCO3(-)) and temperature (15-65 °C) in photoreaction were also investigated. The CuFe2O4@C3N4 sample exhibited stable performance without obvious loss of catalytic activity after five successive runs, showing a promising application for the photo-oxidative degradation of environmental contaminants. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Temperature induced phase transformations and microstructural changes in nanostructured FeCu solid solutions using in situ neutron powder thermo-diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Blanco, D. [Unidad de Magnetometria, SCT' s, Universidad de Oviedo, Julian Claveria, 8, 33006 Oviedo (Spain); Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo s/n, Oviedo 33007 (Spain); Gorria, P., E-mail: pgorria@uniovi.e [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo s/n, Oviedo 33007 (Spain); Blanco, J.A. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo s/n, Oviedo 33007 (Spain); Smith, R.I. [ISIS facility, RAL, Chilton, Didcot, Oxon OX11 0QX (United Kingdom)

    2009-08-26

    In situ neutron powder thermo-diffraction experiments in the temperature range from 300 K to 1170 K have been carried out in nanostructured and metastable Fe{sub 15}Cu{sub 85} and Fe{sub 85}Cu{sub 15} solid solutions, which were synthesized by means of a mechanical alloying technique. We report on the microstructural changes and the phase transformations that take place during controlled heating and cooling processes. The average crystalline grain size is similar for both samples in the as-milled state (approx16-20 nm) while the induced strain is 2.5 times higher in the Fe-rich powders, reaching 1%. Moreover, the alpha-gamma transformation for Fe{sub 15}Cu{sub 85} starts at temperatures lower (approx900 K) than that expected for pure Fe (1183 K) due likely to the existence of local inhomogeneities in the composition of the ball milled material.

  3. Microstructures in Fe30Ni30Cu20P10Si5B5 melt-spun alloy ejected at various temperatures

    OpenAIRE

    K. Ziewiec; A. Ziewiec; K. Prusik

    2009-01-01

    Purpose: The aim of the work is to study the influence of ejection temperature on the structure of Fe30Ni30Cu20P10Si5B5 melt-spun.Design/methodology/approach: A six-component Fe30Ni30Cu20P10Si5B5 alloy was arc-melt in argon protective atmosphere from of pure Fe, Ni, Cu elements and Fe-P, Fe-B, Ni-P, Ni-B master alloys and melt-spun in helium. The alloy was melt-spun in various temperatures. Morphology and chemical composition of the cross-section of the ingot and melt-spun ribbons were analys...

  4. Slurry nebulization ICP-OES for the determination of Cu, Fe, Mg, Mn and Zn in bovine liver

    Directory of Open Access Journals (Sweden)

    Ntebogeng S. Mokgalaka

    2008-12-01

    Full Text Available A method that involves analysis of bovine liver by slurry nebulization and ICP-OES has been developed. This method permits rapid and accurate determination of Cu, Fe, Mg, Mn and Zn in bovine liver. Aliquots of freeze-dried and powdered bovine liver sample were dispersed in 2.0 M HNO3 and sonicated to homogenize the resulting slurries. Bovine liver samples were also microwave digested or subjected to aqueous extraction for comparison of analytical results. Concentrations of Cu, Fe, Mg, Mn and Zn in aqueous slurries, the digests, and aqueous extracts were determined by the ICP-OES using external calibration curves. A student’s t-test showed that the results obtained using the slurry method were in good agreement at 95 % confidence level (CL with those of microwave digestion or aqueous extraction techniques, except for Fe. To check the accuracy and precision of the slurry method, a bovine liver CRM was analyzed and good agreement was achieved with the certified values at 95 % CL. The results demonstrate inefficiency of aqueous extraction technique for complete removal of Fe in bovine liver sample.

  5. Mineralogy and skarnification processes at the Avan Cu-Fe Skarn, northeast of Kharvana, NW Iran

    Directory of Open Access Journals (Sweden)

    Mir Ali Asghar Mokhtari

    2017-02-01

    Full Text Available Introduction The Avan Cu-Fe skarn is located at the southern margin of Qaradagh batholith, about 60 km north of Tabriz. The Skarn-type metasomatic alteration is the result of Qaradagh batholith intrusion into the Upper Cretaceous impure carbonates. The studied area belongs to the Central Iranian structural zone. In regional scale, the studied area is a part of the Zangezour mineralization zone in the Lesser Caucasus. Several studies (Karimzadeh Somarin and Moayed, 2002; Calagari and Hosseinzadeh, 2005; Mokhtari, 2008; Baghban Asgharinezhad, 2012; Mokhtari, 2012 including master’s theses and research programs have been done on some skarns in the Azarbaijan area considering their petrologic and mineralization aspects. However, before this study, the Avan skarn aureole has not been studied in detail. In this paper, various geological aspects of the Avan skarn including mineralogy, bi-metasomatic alteration, metasomatism and mineralization during the progressive and retrograde stages of the skarnification processes have been studied in detail. Research Method This research consists of field and laboratory studies. Field studies include preparation of the geological map, identifying the relationship between the intrusion and the skarn aureole, identifying the relationship between different parts of the skarn zone and also collecting samples for laboratory studies. Laboratory studies include petrography, mineralography and microprobe studies. Cameca SX100 Microprobe belonging to Geological Survey of the Czech Republic was used in order to determine the chemical composition of the calc-silicate minerals such as pyroxene and garnet in garnet skarn and pyroxene- garnet skarn sub-zones. Discussion and conclusion Qaradagh batholith is composed of discrete acid to mafic phases including gabbro, diorite, quartz diorite, quartz monzonite, quartz monzodiorite, tonalite, granodiorite, monzogranite and granite porphyry which is dominated by granodiorite

  6. The metal-insulator transition in Fe{sub 1.01-x}Cu{sub x}Se

    Energy Technology Data Exchange (ETDEWEB)

    Williams, A J; McQueen, T M; Cava, R J [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States); Ksenofontov, V; Felser, C [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitaet, Staudinger Weg 9, D-55099 Mainz (Germany)

    2009-07-29

    Iron selenide, Fe{sub 1.01}Se, the layered parent compound of the recently discovered superconducting arsenide family, has previously been shown to be non-magnetic and superconducting with a critical temperature of 8 K. Here we show that copper can be substituted at the iron site in Fe{sub 1.01}Se up to a solubility limit of 20-30%, after which a first-order transition to the three-dimensional CuFeSe{sub 2} structure type is observed. As little as 1.5% copper is sufficient to suppress the superconductivity, and 4% drives the system through a metal-insulator transition. A local magnetic moment is introduced, which maximizes near 12% doping, where a spin-glass transition near 15 K is observed.

  7. Chemical synthesis and structural characterization of the substitution compound LaFe{sub 1-x}Cu{sub x}O{sub 3} (x = 0-0.40)

    Energy Technology Data Exchange (ETDEWEB)

    Caronna, Tullio; Fontana, Francesca [INSTM R.U. and Department of Industrial Eng., University of Bergamo, viale Marconi 5, Dalmine I-24044 (Italy); Sora, Isabella Natali, E-mail: isabella.natali-sora@unibg.it [INSTM R.U. and Department of Industrial Eng., University of Bergamo, viale Marconi 5, Dalmine I-24044 (Italy); Pelosato, Renato [INSTM R.U. and Department of Industrial Eng., University of Bergamo, viale Marconi 5, Dalmine I-24044 (Italy)

    2009-08-15

    LaFe{sub 1-x}Cu{sub x}O{sub 3} samples with x = 0, 0.05, 0.10, 0.20 and 0.40 were prepared by citrate auto-combustion synthesis; up to x = 0.20 lanthanum ferrites are free from impurity, while for x = 0.40 molar content of copper a small amount of La{sub 2}CuO{sub 4} and traces of CuO are present. The crystal structures of LaFe{sub 1-x}Cu{sub x}O{sub 3}, with x = 0.05, 0.10 and 0.20 have been established through the Rietveld method applied to powder X-ray diffraction data. All compounds exhibit the orthorhombic symmetry (space group Pnma) and crystallize in the perovskite-like cell of LaFeO{sub 3}, with octahedral sites occupied by a mixture of Fe and Cu and lanthanum atoms 12-fold coordinated. For x = 0-0.20 the oxidation state of iron cations was determined by redox titration to be Fe{sup 3+}. The charge compensation required by the substitution of Fe{sup 3+} by Cu{sup 2+} is achieved by the elimination of oxygen atoms. The consistency of the crystal data with the charge compensation mechanism is discussed.

  8. Synthesis and properties of ZnO-HMD@ZnO-Fe/Cu core-shell as advanced material for hydrogen storage.

    Science.gov (United States)

    Bouazizi, N; Boudharaa, T; Bargougui, R; Vieillard, J; Ammar, S; Le Derf, F; Azzouz, A

    2017-04-01

    In this paper, a new synthetic strategy towards functionalized ZnO-HMD@ZnO-Fe/Cu core-shell using sol-gel process modified by chemical grafting of hexamethylenediamine (HMD) on the core and in-situ dispersion of Cu(0)/Fe(0) as metallic nanoparticles (M-NPs) on the shell. The as-prepared core-shell materials were fully characterized by transmission electron microscopy, X-ray powder diffractometry, diffuse reflectance and FT-IR spectrophotometery, photoluminescence, and complexes impedance spectroscopy measurements. The XRD patterns agreed with that of the ZnO typical wurtzite structure, indicating good crystallinity of ZnO-HMD@ZnO-Fe/Cu, with the presence of Fe(0) and Cu(0) phases. Hexamethylenediamine grafting and M-NPs insertion were highly activated and enhanced the core and shell interface by the physiochemical interaction. After functionalization, luminescence intensities and electrical properties of both core and core-shell nanoparticles are improved, indicating the effects of the surface groups on the charge transfer of ZnO-HMD@ZnO-Fe/Cu. The hydrogen capacity retention was depended strongly on the composition and structure of the obtained core-shell. Iron/Copper-loaded ZnO-HMD@ZnO materials exhibited the highest capacity for hydrogen storage. The excellent stability and performance of the ZnO-HMD@ZnO-Fe/Cu core-shell make it an efficient candidate for hydrogen storage. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Experimental and theoretical study of the oxidation of ventilation air methane over Fe2O3 and CuO.

    Science.gov (United States)

    Jin, Yonggang; Sun, Chenghua; Su, Shi

    2015-07-07

    Coal mine ventilation air methane (VAM) is an important contributor to methane emissions from the energy sector. Although various technologies are under development, treatment of the VAM with an efficient and cost-effective approach has been an ongoing challenge due to massive flow rates of the ventilation air and low and variable methane concentrations. Recently a new concept based on the principle of chemical looping combustion (CLC) has been proposed for VAM abatement (Appl. Energy, 2014, 113, 1916), in which oxidation of low-concentration CH4 balanced by N2 with Fe2O3 or CuO as the oxygen carrier was studied. Here, we thoroughly examined the feasibility of CLC of VAM based on experimental study and theoretical calculations. Reduction of Fe2O3 and CuO and evolution of gas products during CH4 oxidation were investigated using TGA-MS under two reaction atmospheres: 1 vol% CH4 balanced by N2 and the simulated VAM containing 1 vol% CH4, 20 vol% O2, 0.4 vol% CO2 and balance N2. It was found that the CLC of VAM is fundamentally infeasible because the reduced phase of Fe2O3 and CuO cannot be formed for chemical looping when reacting with the simulated VAM containing abundant oxygen. Theoretical calculations revealed that Fe2O3 and CuO remain stable without the transition to the reduced phase as the generated oxygen vacancy on the surface of metal oxides during CH4 oxidation can recover quickly with O2 adsorption and dissociation. Calculations confirmed that both Fe2O3 and CuO play a role of surface catalyst in VAM oxidation. More importantly, it was found that the low-coordinated metal atoms and oxygen vacancies can stabilize CHx radicals to promote the dissociation of CH4, which is generally the rate-determining step for CH4 oxidation. Such findings are useful for new development and understanding of high-performance and low-cost metal oxide catalysts for CH4 oxidation.

  10. Crystal structure and electrical conductivity of {alpha}'''-[BEDT-TTF]{sub 12}[Cu{sub 2}Br{sub 4}]{sub 3} (BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene)

    Energy Technology Data Exchange (ETDEWEB)

    Kubo, Kazuya, E-mail: kkubo@m.tains.tohoku.ac.j [Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki-Aza-Aoba, Aoba-Ku, Sendai, Miyagi 980-8578 (Japan); Miyasaka, Hitoshi; Yamashita, Masahiro [Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki-Aza-Aoba, Aoba-Ku, Sendai, Miyagi 980-8578 (Japan)

    2010-06-01

    A new non-integer valence salt based on bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with a dianionic dinuclear cupper(I) complex, {alpha}'''-[BEDT-TTF]{sub 12}(Cu{sup I}{sub 2}Br{sub 4}){sub 3}, was selectively synthesized by a diffusion of BEDT-TTF in tetrahydrofurane (THF) and a mixture of Cu{sup II}X{sub 2} (X=Br or Cl) in methanol. An alternating stacking arrangement of the BEDT-TTF layers and inorganic layers of the Cu{sup I}{sub 2}Br{sub 4}{sup 2-} anions is formed, where the BEDT-TTF layer involves six crystallographically independent molecules. Overlap integral calculation among BEDT-TTF donors in the salt suggests the existence of two-dimensional interactions among the donors. The compound exhibits semiconducting behavior in the wide range of temperature of room temperature to 2 K ({rho}{sub r.t.}=0.3 {Omega} cm, E{sub a}=0.08 eV in a crystal) without structural phase transition at ambient pressure.

  11. Radical scavenging propensity of Cu2 +, Fe3 + complexes of flavonoids and in-vivo radical scavenging by Fe3 +-primuletin

    Science.gov (United States)

    Jabeen, Erum; Janjua, Naveed Kausar; Ahmed, Safeer; Murtaza, Iram; Ali, Tahir; Hameed, Shahid

    2017-01-01

    Cu2 + and Fe3 + complexes of three flavonoids (morin or mo, quercetin or quer and primuletin or prim) were synthesized with the objective of improving antioxidant capacities of flavonoids. The radical scavenging activities of pure flavonoids and their metal complexes were assayed to monitor their tendencies towards sequestering of radicals at physiological conditions. The scavenger potencies of metal-flavonoid complexes were significantly higher than those of the parent flavonoids. Further, influence of the solvent polarity on the radical capturing by flavonoids and their metal complexes was in favor for the polar solvent. Fe3 +-prim displayed its radical scavenging ability via up gradation of CAT and SOD activities in in-vivo antioxidant assays.

  12. Ferroelectric property of (Ba,Bi)(Ti,M)O{sub 3} (M; Cu, Mn, Al, Fe, In, Y, Yb) ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Shiroki, K; Ogiso, H; Yonesaki, Y; Takei, T; Kinomura, N; Wada, S [Department of Research Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Miyamae-cho 7-32, Kofu, Yamanashi, 400-8511 (Japan); Kumada, N, E-mail: kumada@yamanashi.ac.jp

    2011-10-29

    Two types of solid solutions, (Ba{sub 1-2x}Bi{sub 2x})(Cu{sub x}Ti{sub 1-x})O{sub 3} (x {<=} 0.04) and (Ba{sub 1-x}Bi{sub x})(M{sub x}Ti{sub 1-x})O{sub 3} (M; Al, Mn, Fe, In, Y, Yb; x {<=} 0.03) were prepared by conventional high temperature reaction. For the solid solution of (Ba{sub 1-2x}Bi{sub 2x})(Cu{sub x}Ti{sub 1-x})O{sub 3} single phases with the tetragonal cell was obtained in the region of x {<=} 0.04 and for the solid solutions of (Ba{sub 1-x}Bi{sub x})(M{sub x}Ti{sub 1-x})O{sub 3} (M; Al, Mn, Fe, In, Y, Yb) single phases with the tetragonal cell was observed in the region of x {<=} 0.03 except the sample of M = Al in which a small amount of the second phase was contained. In these solid solutions the T{sub c} increased with the value of x except for M = Al, and was 144.7deg. C for x = 0.020 of M = Cu, and the highest T{sub c} was observed for x = 0.020 of every M atom and the order of the highest T{sub c} was Cu (144.7 deg. C), Y (141.4 deg. C), Yb (140.8 deg. C), In (138.5 deg. C), Mn (135.5 deg. C) and Fe (131.3 deg. C). The highest apparent piezoelectric constant, (d{sub 33} = 258 pm/V) in these solid solutions was observed for x = 0.010 of Al.

  13. Martensitic transformation of {gamma}-Fe particles during compression of Cu-Fe single crystals in connection with prior coherency loss

    Energy Technology Data Exchange (ETDEWEB)

    Wusatowska-Sarnek, A.M.; Miura, Hiromi; Sakai, Taku

    1998-10-13

    There have been numerous studies on martensitic transformation (MT) of iron particles embedded in copper single crystals. The precipitate particles of f.c.c. {gamma}-Fe phase have a good coherency with the Cu matrix and do not transform to b.c.c. {alpha}-Fe one on cooling, even down to the liquid helium temperature. Introduction of defects by plastic deformation or ion bombardment, however, cause them to transform to {alpha}-Fe. This kind of particle-matrix system is suitable for studying MT, because MT begins at pre-determined nucleation sites and takes place in discrete volumes providing no autocatalysis. This transformation contrasts with the martensitic reactions in bulk samples. However a mechanism for the MT start in such particles is still not clarified. It was suggested that the MT is initiated with the aid of an applied stress by aiding the lattice shear in {l_brace}111{r_brace}{sub f}{l_angle}211{r_angle}{sub f} systems. In the present study, the effect of {gamma}Fe particle size on the MT was investigated from the standpoint of prior coherency loss.

  14. Pyrosequencing investigation into the influence of Cu2+, Zn2+, Fe2+ and I− mixtures on fungal diversity and toxigenic fungal growth in a fermented liquid feed

    Directory of Open Access Journals (Sweden)

    Yuyong He

    2016-03-01

    Full Text Available A L9(34 orthogonal experiment was conducted to evaluate the influence of 9 mixtures which consisted of Cu2+, Zn2+, Fe2+ and I− ions at different ion concentrations on fungal diversity and toxigenic fungal growth in a Bacillus subtilis-fermented liquid feed (FLF using pyrosequencing. The maximal Chao estimator and Shannon index were achieved in the FLF with a mixture of Cu2+ (200 mg/kg, Zn2+ (160 mg/kg, Fe2+ (150 mg/kg and I− (2.4 mg/kg. The minimal relative abundance of Aspergillus was achieved when a mixture of Cu2+ (200 mg/kg, Zn2+, Fe2+ and I− was added to the FLF. Compared with Zn2+, Fe2+ and I−, Cu2+ was the most important ion in inhibiting Aspergillus growth. Adding Zn2+ (160 mg/kg, Cu2+, Fe2+ and I− to the FLF minimized the relative abundance of Fusarium. It was Zn2+ instead of Cu2+ played a critical role in suppressing the growth of Fusarium. The proper use of the mixture of Cu2+, Zn2+, Fe2+ and I− in FLF contributes to inhibit the growth of mycotoxin-producing fungi during storage. The new findings of this study help farmers properly use the mixture of Cu2+, Zn2+, Fe2+ and I− to inhibit the growth of mycotoxin-producing fungi in the production of high quality FLF and alleviate mycotoxins damages to animals and humans.

  15. Evaluation of Antioxidant and Cytotoxicity Activities of Copper Ferrite (CuFe2O4 and Zinc Ferrite (ZnFe2O4 Nanoparticles Synthesized by Sol-Gel Self-Combustion Method

    Directory of Open Access Journals (Sweden)

    Samikannu Kanagesan

    2016-08-01

    Full Text Available Spinel copper ferrite (CuFe2O4 and zinc ferrite (ZnFe2O4 nanoparticles were synthesized using a sol-gel self-combustion technique. The structural, functional, morphological and magnetic properties of the samples were investigated by Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, Transmission electron microscopy (TEM and vibrating sample magnetometry (VSM. XRD patterns conform to the copper ferrite and zinc ferrite formation, and the average particle sizes were calculated by using a transmission electron microscope, the measured particle sizes being 56 nm for CuFe2O4 and 68 nm for ZnFe2O4. Both spinel ferrite nanoparticles exhibit ferromagnetic behavior with saturation magnetization of 31 emug−1 for copper ferrite (50.63 Am2/Kg and 28.8 Am2/Kg for zinc ferrite. Both synthesized ferrite nanoparticles were equally effective in scavenging 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH free radicals. ZnFe2O4 and CuFe2O4 nanoparticles showed 30.57% ± 1.0% and 28.69% ± 1.14% scavenging activity at 125 µg/mL concentrations. In vitro cytotoxicity study revealed higher concentrations (>125 µg/mL of ZnFe2O4 and CuFe2O4 with increased toxicity against MCF-7 cells, but were found to be non-toxic at lower concentrations suggesting their biocompatibility.

  16. Synthesis and characterization of noble metal nanocomposites: Ag/Fe3O4/ZnO and Ag/Fe3O4/CuO/ZnO for better photocatalytic activity under visible light irradiation

    Science.gov (United States)

    Tju, H.; Prakoso, S. P.; Taufik, A.; Saleh, R.

    2017-04-01

    Nobel metal such as silver (Ag) nanoparticles have been proven could enhance photocatalytic activity under visible light irradiation and prevent recombination of electron and hole. Fe3O4/ZnO and Fe3O4/CuO/ZnO has been investigated in our previous study. So in this work, a magnetic Ag/Fe3O4/ZnO and Ag/Fe3O4/CuO/ZnO nanocomposites were successfully synthesized using sol-gel method. The as-synthesized products were characterized by X-ray diffraction and ultraviolet-visible (UV-Vis) spectroscopy. The results showed that the nanocomposites were the combination of the desired nanoparticles. From the UV-Vis absorption spectra, we found the surface plasmon resonance (SPR) to be around ~440 nm. Under visible light irradiation, the Ag/Fe3O4/ZnO and Ag/Fe3O4/CuO/ZnO nanocomposites exhibited much higher photocatalytic activity than the Fe3O4/ZnO and Fe3O4/CuO/ZnO. The effect of catalyst dosage and initial concentration of methylene blue (MB) were also tested. To understand the mechanism in photocatalytic activity, several scavengers were tested. The reusability study suggested that the prepared nanocomposites can still maintain the degradation efficiency after four cycles, showing great potential for water purification.

  17. Charge disproportionation associated with spin ordering in delafossite CuFeO2 as seen via resonant x-ray diffraction

    Science.gov (United States)

    Terada, N.; Nakajima, T.; Mitsuda, S.; Tanaka, Y.; Mamiya, H.; Kitazawa, H.

    2010-02-01

    We have performed the resonant x-ray diffraction measurements on the triangular lattice antiferromagnet CuFeO2 near the FeK absorption edge. The resonant enhancement of the space-group-forbidden superlattice 010 reflection was observed below the second Néel temperature TN2=11K at which the four-sublattice ground state is stabilized. The significant azimuthal angle dependence of the superlattice reflection was not observed. On the other hand, the energy spectrum can be explained by the charge disproportionation (CD) model, 2Fe3+↔Fe(3+δ)++Fe(3-δ)+ . We discuss the relationship between the unconventional collinear four-sublattice ground state and the CD state in CuFeO2 .

  18. Magnetic properties of quadruple perovskite solid solutions Ca{sub 1–x}Y{sub x}Cu{sub 3}Fe{sub 4}O{sub 12} and Y{sub 1–y}Ce{sub x}Cu{sub 3}Fe{sub 4}O{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Makoto; Mori, Shigeo [Department of Materials Science and Engineering, Osaka Prefecture University, Osaka 599-8531 (Japan); Yamada, Ikuya, E-mail: i-yamada@21c.osakafu-u.ac.jp [Nanoscience and Nanotechnology Research Center, Osaka Prefecture University, Osaka 599-8570 (Japan)

    2016-08-26

    Magnetic properties of the quadruple perovskite solid solutions Ca{sub 1–x}Y{sub x}Cu{sub 3}Fe{sub 4}O{sub 12} and Y{sub 1–y}Ce{sub y}Cu{sub 3}Fe{sub 4}O{sub 12} are investigated. Ca{sub 1–x}Y{sub x}Cu{sub 3}Fe{sub 4}O{sub 12} shows continuous increase in the ferromagnetic transition temperature as x increases. Y{sub 1–y}Ce{sub y}Cu{sub 3}Fe{sub 4}O{sub 12} exhibits a ferromagnetic-antiferromagnetic transition in the vicinity of y = 0.5. These observations demonstrate the electron doping effect on magnetic properties of charge-disproportionated ACu{sub 3}Fe{sub 4}O{sub 12} phases.

  19. Structure and High Temperature Thermoelectric Properties of Delafossite-Type Oxide CuFe1-xNixO2 (0 ≤ x ≤ 0.05)

    Science.gov (United States)

    Hayashi, Kei; Nozaki, Tomohiro; Kajitani, Tsuyoshi

    2007-08-01

    We have investigated crystal structure of delafossite-type oxide CuFe1-xNixO2 (0 ≤ x ≤ 0.05) and measured its thermoelectric properties at high temperatures ranging from 300 and 1100 K. The lattice parameter a of the Ni2+-doped samples is nearly equal to that of CuFeO2, while the lattice parameter c of the Ni2+-doped samples increases. Nearly constant a-axis is due to the decrease of (Fe/Ni)-O distance and simultaneous increase of O-(Fe/Ni)-O angle. Increase of the c-axis is due to the increase of Cu-O distance in the Ni2+-doped samples. The valence states of the Fe- and Cu-sites are calculated from bond valence summation. The valence state of the Fe-site in the Ni2+-doped samples is larger than that of CuFeO2, an indication of hole doping in the Fe-site. This increase of hole carriers enhances the electrical conductivity σ. The highest electrical conductivity is 18 S/cm. Although the Seebeck coefficient S decreased by Ni2+ doping, the S is still high value (S>250 μV/K). The thermal conductivity κ of CuFe1-xNixO2 is relatively high (κ>4 W/mK). The maximum dimensionless figure of merit ZT=σ S2T/κ=0.14 is obtained with the sample of x=0.01 at 1100 K, being higher than that of the polycrystalline γ-Na0.7CoO2. There is no significant evaporation of the constituent elements after the heat cycles.

  20. Copper-promoted circumneutral activation of H2O2 by magnetic CuFe2O4 spinel nanoparticles: Mechanism, stoichiometric efficiency, and pathway of degrading sulfanilamide.

    Science.gov (United States)

    Feng, Yong; Liao, Changzhong; Shih, Kaimin

    2016-07-01

    To evaluate the heterogeneous degradation of sulfanilamide by external energy-free Fenton-like reactions, magnetic CuFe2O4 spinel nanoparticles (NPs) were synthesized and used as catalysts for activation of hydrogen peroxide (H2O2). The physicochemical properties of the CuFe2O4 NPs were characterized with several techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and magnetometry. In the catalytic experiments, CuFe2O4 NPs/H2O2 oxidation showed the best degradation performance in the circumneutral conditions that resulted from the presence of Cu(II) on the surface of the CuFe2O4 NPs. The surface area-normalized pseudo-first-order rate constants were calculated as 2.60 × 10(-2) L m(-1) min(-1), 2.58 × 10(-3) L m(-1) min(-1), 1.92 × 10(-3) L m(-1) min(-1), and 7.30 × 10(-4) L m(-1) min(-1) for CuO, CuFe2O4 NPs, Fe3O4, and α-Fe2O3 catalysts, respectively. Thus, solid state Cu(II) was more reactive and efficient than Fe(III) in the circumneutral activation of H2O2; this finding was further supported by the results regarding the stoichiometric efficiency of H2O2. The effects of experimental parameters such as the oxidant dosage and catalyst loading were investigated. The mechanism for H2O2 activation on the spinel surface was explored and could be explained by the solid redox cycles of Fe(II)/Fe(III) and Cu(II)/Cu(I). Based on the products detected, a degradation pathway via the CS bond cleavage is proposed for the degradation of sulfanilamide. The findings of this study suggest that copper can be used as a doping metal to improve the reactivity and expand the effective pH range of iron oxides. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Thin films preparation by rf-sputtering of copper/iron ceramic targets with Cu/Fe=1: From nanocomposites to delafossite compounds

    OpenAIRE

    Mugnier, Emmanuelle; Barnabé, Antoine; Presmanes, Lionel; Tailhades, Philippe

    2008-01-01

    In the Cu–Fe–O phase diagram, delafossite CuFeO2 is obtained for the CuI oxidation state and for the Cu/Fe=1 ratio. By decreasing the oxygen content, copper/spinel oxide composite can be obtained because of the reduction and the disproponation of cuprous ions. Many physical properties as for instance, electrical, optical, catalytic properties can then be affected by the control of the oxygen stoichiometry. In rf-sputtering technique, the bombardment energies on the substrate can be c...

  2. Corrosion and protection of heterogeneous cast Al-Si (356) and Al-Si-Cu-Fe (380) alloys by chromate adn cerium inhibitors

    Science.gov (United States)

    Jain, Syadwad

    In this study, the localized corrosion and conversion coating on cast alloys 356 (Al-7.0Si-0.3Mg) and 380 (Al-8.5Si-3.5Cu-1.6Fe) were characterized. The intermetallic phases presence in the permanent mold cast alloy 356 are primary-Si, Al5FeSi, Al8Si6Mg3Fe and Mg2Si. The die cast alloy 380 is rich in Cu and Fe elements. These alloying elements result in formation of the intermetallic phases Al 5FeSi, Al2Cu and Al(FeCuCr) along with primary-Si. The Cu- and Fe-rich IMPS are cathodic with respect to the matrix phase and strongly govern the corrosion behavior of the two cast alloys in an aggressive environment due to formation of local electrochemical cell in their vicinity. Results have shown that corrosion behavior of permanent mould cast alloy 356 is significantly better than the die cast aluminum alloy 380, primarily due to high content of Cu- and Fe-rich phases such as Al2Cu and Al 5FeSi in the latter. The IMPS also alter the protection mechanism of the cast alloys in the presence of inhibitors in an environment. The presence of chromate in the solution results in reduced cathodic activity on all the phases. Chromate provides some anodic inhibition by increasing pitting potentials and altering corrosion potentials for the phases. Results have shown that performance of CCC was much better on 356 than on 380, primarily due to inhomogeneous and incomplete coating deposition on Cu- and Fe- phases present in alloy 380. XPS and Raman were used to characterize coating deposition on intermetallics. Results show evidence of cyanide complex formation on the intermetallic phases. The presence of this complex is speculated to locally suppress CCC formation. Formation and breakdown of cerium conversion coatings on 356 and 380 was also analyzed. Results showed that deposition of cerium hydroxide started with heavy precipitation on intermetallic particles with the coatings growing outwards onto the matrix. Electrochemical analysis of synthesized intermetallics compounds in the

  3. The metal-rich portions of the phase system Cu-Fe-Pd-S at 100°c, 900°c and 725°c

    DEFF Research Database (Denmark)

    Karup-Møller, Sven; Makovicky, Emil; Barnes, Sarah-Jane

    2008-01-01

    The sulphur-poor portions of the dry condensed Cu-Fe-Pd-S system were studied at 1000°C, 900°C and 725°C by synthesis in evacuated silicate glass tubes, along with textural observations and electron microprobe analyses of equilibrated reaction products. Sulphide melt coexists with Cu-Fe-Pd alloys......-melt. Formation of the two new Cu-Pd alloy minerals, skaergaardite and nielsenite, is discussed in terms of the present findings.......The sulphur-poor portions of the dry condensed Cu-Fe-Pd-S system were studied at 1000°C, 900°C and 725°C by synthesis in evacuated silicate glass tubes, along with textural observations and electron microprobe analyses of equilibrated reaction products. Sulphide melt coexists with Cu-Fe-Pd alloys......, bornite, Fe1-xS and iss (intermediate solid solution, Cabri, 1973) and Pd4S. Compositional data were obtained for the associations bornite-alloy-melt, pyrrhotite-alloy-melt and for immiscible Cu-rich sulphide melts. Partition coefficients for all three metals were derived for the association alloy...

  4. Spin crossover at magnetic phase transformation in YBa sub 2 (Cu sub 1 sub - sub x Fe sub x) sub 3 O sub 7 sub+- subdelta superconductors

    CERN Document Server

    Lyubutin, I S

    2001-01-01

    It is established that all iron ions in the Cu1 and Cu2 local nodes in the YBa sub 2 (Cu sub 0 sub . sub 9 sup 5 sup 7 Fe sub 0 sub . sub 1) sub 3 O sub 7 sub . sub 0 sub 1 superconducting compound with the T sub c = 31 K at the temperature below T sub m = 22 K become magneto-ordered. Thus, the magnetic order by the T < T sub m coexists with the superconductivity. It is determined through the Moessbauer spectroscopy method that the iron ions in the Cu2 (Fe2) nodes at the temperature T < T sub m are in the low-spin state (S 3/2 or 1/2), whereas the same quantity of the iron ions in the Cu1 (Fe1) nodes is in the Fe sup 3 sup + high-spin state (S = 5/2). By the magnetic transition near T sub m these ions change the spin values and transit form low-spin state to the high-spin one and vice versa. Control measurements on other samples of the YBa sub 2 (Cu sub 1 sub - sub x Fe sub x) sub 3 O sub 7 sub+- subdelta series confirm these conclusions

  5. Phase-transformation in iron oxide and formation of Cu/γ-Fe2O3 nanocomposite using radio-frequency sputtering with metal chips on an α-Fe2O3 target

    Directory of Open Access Journals (Sweden)

    Seishi Abe

    2017-07-01

    Full Text Available A simple technique that uses radio-frequency sputtering with a functional element on a hematite (α-Fe2O3 target is presented for the production of maghemite (γ-Fe2O3 thin films. These films are prepared on water-cooled glass substrates in an Ar atmosphere. Investigations are done with Ti, Si, Al, Cu, Mo, and Zn, with γ-Fe2O3 being obtained only in the presence of Cu, indicating that phase transition occurs only for this metal. Mössbauer spectra and magnetization analysis reveal that the quality of the obtained γ-Fe2O3 films is higher than that of the film produced using Mg, which was reported in our previous work. High-angle annular dark-field scanning tunneling electron microscopy and electron energy-loss spectroscopy reveal that the added Cu remains in a metallic state (without oxidization, forming a Cu/γ-Fe2O3 phase-mixture in the as-deposited film. The Cu/γ-Fe2O3 composite film exhibits negative magnetoresistance (MR, with a MR ratio of approximately 0.6% at room temperature in an applied field of 10 kOe, and a negative Faraday rotation of −5708 deg cm−1 at 830 nm.

  6. Phase-transformation in iron oxide and formation of Cu/γ-Fe2O3 nanocomposite using radio-frequency sputtering with metal chips on an α-Fe2O3 target

    Science.gov (United States)

    Abe, Seishi; Watanabe, Masato

    2017-07-01

    A simple technique that uses radio-frequency sputtering with a functional element on a hematite (α-Fe2O3) target is presented for the production of maghemite (γ-Fe2O3) thin films. These films are prepared on water-cooled glass substrates in an Ar atmosphere. Investigations are done with Ti, Si, Al, Cu, Mo, and Zn, with γ-Fe2O3 being obtained only in the presence of Cu, indicating that phase transition occurs only for this metal. Mössbauer spectra and magnetization analysis reveal that the quality of the obtained γ-Fe2O3 films is higher than that of the film produced using Mg, which was reported in our previous work. High-angle annular dark-field scanning tunneling electron microscopy and electron energy-loss spectroscopy reveal that the added Cu remains in a metallic state (without oxidization), forming a Cu/γ-Fe2O3 phase-mixture in the as-deposited film. The Cu/γ-Fe2O3 composite film exhibits negative magnetoresistance (MR), with a MR ratio of approximately 0.6% at room temperature in an applied field of 10 kOe, and a negative Faraday rotation of -5708 deg cm-1 at 830 nm.

  7. Monohalogenated ferrocenes C5H5FeC5H4 X (X = Cl, Br and I) and a second polymorph of C5H5FeC5H4I

    Science.gov (United States)

    Romanov, Alexander S.; Mulroy, Joseph M.; Khrustalev, Victor N.; Antipin, Mikhail Yu.; Timofeeva, Tatiana V.

    2009-01-01

    The structures of the three title monosubstituted ferrocenes, namely 1-chloro­ferrocene, [Fe(C5H5)(C5H4Cl)], (I), 1-bromo­ferrocene, [Fe(C5H5)(C5H4Br)], (II), and 1-iodo­ferrocene, [Fe(C5H5)(C5H4I)], (III), were determined at 100 K. The chloro- and bromo­ferrocenes are isomorphous crystals. The new triclinic polymorph [space group P , Z = 4, T = 100 K, V = 943.8 (4) Å3] of iodo­ferrocene, (III), and the previously reported monoclinic polymorph of (III) [Laus, Wurst & Schottenberger (2005 ▶). Z. Kristallogr. New Cryst. Struct. 220, 229–230; space group Pc, Z = 4, T = 100 K, V = 924.9 Å3] were obtained by crystallization from ethanolic solutions at 253 and 303 K, respectively. All four phases contain two independent mol­ecules in the unit cell. The relative orientations of the cyclo­penta­dienyl (Cp) rings are eclipsed and staggered in the independent mol­ecules of (I) and (II), while (III) demonstrates only an eclipsed conformation. The triclinic and monoclinic polymorphs of (III) contain nonbonded inter­molecular I⋯I contacts, causing different packing modes. In the triclinic form of (III), the mol­ecules are arranged in zigzag tetra­mers, while in the monoclinic form the mol­ecules are arranged in zigzag chains along the a axis. Crystallographic data for (III), along with the computed lattice energies of the two polymorphs, suggest that the monoclinic form is more stable. PMID:19893225

  8. Cation distribution in CuFe{sub 2}O{sub 4} nanoparticles: Effects of Ni doping on magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Thanh, Nguyen Kim; Loan, To Thanh, E-mail: totloan@itims.edu.vn; Anh, Luong Ngoc; Duong, Nguyen Phuc; Hien, Than Duc [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, Hanoi 100000 (Viet Nam); Soontaranon, Siriwat; Thammajak, Nirawat [Synchrotron Light Research Institute, 111 University Avenue, Suranaree, Muang, Nakhon Ratchasima 30000 (Thailand)

    2016-10-14

    The Cu{sub 1−x}Ni{sub x}Fe{sub 2}O{sub 4} nanoparticles (with x = 0, 0.3, 0.5, 0.7, and 1) were synthesized by using spray co-precipitation method at annealing temperature T{sub a} = 900 °C in air for 5 h. The crystal structure, microstructure, oxidation state, and magnetic properties of the samples were characterized by using X-ray diffraction, synchrotron X-ray diffraction, scanning electron microscopy, X-ray absorption spectroscopy, and vibrating sample magnetometer. It was shown that all the samples have cubic structure. Lattice constant and grain size decrease, while the Curie temperature T{sub C} increases with increasing of Ni{sup 2+} content. A small amount of Fe{sup 2+} was found in all the samples. Cation distribution was determined by using a combination of magnetization measurements, extended X-ray absorption fine structure analysis, and Rietveld refinement from synchrotron X-ray diffraction data. It was indicated that Ni{sup 2+} ions occupy in octahedral site only, while Cu{sup 2+} ions distribute in both tetrahedral and octahedral sites. The variation of magnetic parameters is discussed based on Ni{sup 2+} concentration, grain size, the cation distribution, surface effect, and the presence of Fe{sup 2+} ion in the samples.

  9. Chelation of Cu(II), Zn(II), and Fe(II) by tannin constituents of selected edible nuts.

    Science.gov (United States)

    Karamać, Magdalena

    2009-12-22

    The tannin fractions isolated from hazelnuts, walnuts and almonds were characterised by colorimetric assays and by an SE-HPLC technique. The complexation of Cu(II) and Zn(II) was determined by the reaction with tetramethylmurexide, whereas for Fe(II), ferrozine was employed. The walnut tannins exhibited a significantly weaker reaction with the vanillin/HCl reagent than hazelnut and almond tannins, but the protein precipitation capacity of the walnut fraction was high. The SE-HPLC chromatogram of the tannin fraction from hazelnuts revealed the presence of oligomers with higher molecular weights compared to that of almonds. Copper ions were most effectively chelated by the constituents of the tannin fractions of hazelnuts, walnuts and almonds. At a 0.2 mg/assay addition level, the walnut tannins complexed almost 100% Cu(II). The Fe(II) complexation capacities of the tannin fractions of walnuts and hazelnuts were weaker in comparison to that of the almond tannin fraction, which at a 2.5 mg/assay addition level, bound Fe(II) by approximately 90%. The capacity to chelate Zn(II) was quite varied for the different nut tannin fractions: almond tannins bound as much as 84% Zn(II), whereas the value for walnut tannins was only 8.7%; and for hazelnut tannins, no Zn(II) chelation took place at the levels tested.

  10. Structural and Magnetic Study of Cu x FeCr1- x O2 Oxides Under High External Magnetic Fields

    Science.gov (United States)

    Ozkendir, Osman Murat

    2013-06-01

    The structural, electronic, and magnetic behaviors of Cu x FeCr1- x O2 polycrystals are investigated. Investigations are conducted for increasing chromium substitution, according to varying x values in the formula versus copper, for x = 0, 0.2, 0.4, 0.6, 0.8, and 1. The magnetic response of polycrystalline samples under increasing external magnetic field from 0.4 T to 5 T is also studied. The partial crystal structure deformation/transition from delafossite CuFeO2 structure to corundum-type FeCrO3 structure containing CrO2 and Cr2O3 blocks is determined. The change in the crystal structure geometry with increasing Cr substitution is observed. Besides, prominent changes in magnetic ordering are observed from antiferromagnetic ( x = 1, 0.8, and 0.6) to ferromagnetic ordering ( x = 0.4 and 0.2) for high applied external magnetic fields above 2 T.

  11. Microstructure and mechanical properties of nonmagnetic Fe-25Mn-xCu-C steels by super solidus liquid phase sintering

    Science.gov (United States)

    Jia, Shanquan; Xiao, Zhiyu; Wang, Jun; Yang, Shuo; Guan, Hangjian; Zhu, Quanli

    2016-11-01

    In this work, nonmagnetic steels Fe-25Mn-xCu-C were prepared by high manganese pre-alloyed steel powders through powder metallurgy (PM) technique. Four types of steels specimen were created to investigate the microstructure evolving with sintering process, mechanical properties and magnetic properties. The microstructures, fracture surfaces, phase constitutions and mechanical properties of Fe-25Mn-xCu-C were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), and tensile strength test. The results showed that super solidus liquid-phase sintering (SLPS) phenomenon was conclusively verified, for the first time, in the Fe-Mn pre-alloyed powders: Liquids generated by SLPS process from pre-alloyed powders could improve the binding condition between the particles and enhance the densification. X-ray diffraction (XRD) experiment and physical property measurement system (PPMS) measurement verified the nonmagnetic properties of steels with single austenite phase. It is confirmed that mechanical properties are intensively influenced by the characteristic and quantity of liquids between the matrix particles. The fracture mechanism of the steel is dominated by intergranular decohesion mode. The preliminary study found this kind of new non-magnetic steel exhibits relatively high density. With the efficiency in fabricating and the non-magnetic property, this work foresees good prospects for application in the steel components manufacturing industry.

  12. A novel reusable nanocomposite adsorbent, xanthated Fe{sub 3}O{sub 4}-chitosan grafted onto graphene oxide, for removing Cu(II) from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinshui, E-mail: jsliu@sina.com; Liu, Wenxiu; Wang, Yiru; Xu, Meijiao; Wang, Bin

    2016-03-30

    Graphical abstract: - Highlights: • Xanthated Fe{sub 3}O{sub 4}-chitosan grafted onto graphene oxide (xanthated Fe{sub 3}O{sub 4}-CS-GO) was synthesized. • Xanthated Fe{sub 3}O{sub 4}-CS-GO demonstrates the high affinity to Cu(II) ions. • The adsorbent can be effectively reused to remove Cu(II) ions. - Abstract: Novel nanocomposites of xanthated Fe{sub 3}O{sub 4}-chitosan grafted onto graphene oxide (xanthated Fe{sub 3}O{sub 4}-CS-GO) were successfully synthesized for the first time using an amidation reaction. The xanthated Fe{sub 3}O{sub 4}-CS-GO was used to remove Cu(II) from aqueous solutions. The xanthated Fe{sub 3}O{sub 4}-CS-GO was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffractometry, and energy dispersive X-ray spectroscopy. The Cu(II) adsorption isotherms for the xanthated Fe{sub 3}O{sub 4}-CS-GO fitted the Langmuir isotherm model. The maximum Cu(II) adsorption capacity of the xanthated Fe{sub 3}O{sub 4}-CS-GO was 426.8 mg g{sup −1}, which is much higher than the maximum adsorption capacities of other adsorbents that have been described in the literature. This was attributed to xanthated Fe{sub 3}O{sub 4}-CS-GO having abundant functional groups. The xanthated Fe{sub 3}O{sub 4}-CS-GO could be regenerated using ethylene diamine tetraacetic acid, and could easily be removed from a liquid using an external magnetic field. These features would allow secondary pollution of the environment to be avoided more easily than is the case for other adsorbents. Cu(II) was adsorbed from aqueous solutions quickly and efficiently by the xanthated Fe{sub 3}O{sub 4}-CS-GO complex, suggesting that xanthated Fe{sub 3}O{sub 4}-CS-GO may be an ideal candidate for removing Cu(II) from wastewater.

  13. Moessbauer Spectroscopic Study of La{sub 22x}Sr{sub 2x}Cu{sub 1x}Fe{sub x}O{sub 4y} (0 {<=} x {<=} 0.5 ) Solid-solution

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jung Chul [Silla University, Busan (Korea, Republic of); Byeon, Song Ho; Kim, Don; Lee Choong Sub [Pukyong National University, Busan (Korea, Republic of)

    2004-01-15

    Tetragonal K{sub 2}N{sub i}F{sub 4}-type La{sub 22x}Sr{sub 2x}Cu{sub 1x}Fe{sub x}O{sub 4y} solid-solution have been synthesized by citrate based sol-gel method. The valence state of iron was determined by Mossbauer spectroscopy and subsequent iodometric titration clearly showed that the copper ions in this solid-solution are in the mixed valence state Cu(II/III). When x {<=} 0.3, Fe(III) is competing with the mixture of Cu(II) and Cu(III) and La{sub 22x}Sr{sub 2x}Cu{sub 1x}Fe{sub x}O{sub 4y} exhibits a metallic character. No evidence for Cu(II)-O-Fe(IV) {r_reversible} Cu(III)-O-Fe(III) valence degeneracy was observed. In contrast, a small amount of Fe(IV) is observed with increasing x (x = 0.4 and 0.5), revealing a semiconducting behavior. These results suggest that the electronic interaction of Cu(III)-O-Fe(III) contributes greatly to the metallic character, while the electronic interaction of Cu(II)-O-Fe(IV) deteriorates the metallic character of La{sub 22x}Sr{sub 2x}Cu{sub 1x}Fe{sub x}O{sub 4y}

  14. Different recycle behavior of Cu2+ and Fe3+ ions for phenol photodegradation over TiO2 and WO3.

    Science.gov (United States)

    Wan, Lianghui; Sheng, Jiayi; Chen, Haihang; Xu, Yiming

    2013-11-15

    Photocatalytic degradation of organic pollutants on TiO2 and WO3 have been widely studied, but the effects of Cu(2+) and Fe(3+) ions still remain unclear. In this work, we have found that the recycle behavior of Cu(2+) and Fe(3+) are greatly dependent on the photocatalytic activity of metal oxide used. With TiO2 (P25, anatase, and rutile), all the time profiles of phenol degradation in water under UV light well fitted to the apparent first-order rate equation. On the addition of Cu(2+), phenol degradation on anatase, rutile and WO3 also followed the first-order kinetics. On the addition of Fe(3+), the initial rate of phenol degradation on each oxide was increased, but only the reactions on three TiO2 became to follow the first order kinetics after half an hour. The relevant rate constants for phenol degradation in the presence of Cu(2+) or Fe(3+) were larger than those in the absence of metal ions. Under visible light, phenol degradation on WO3 was also accelerated on the addition of Fe(3+) or Cu(2+). Moreover, several influencing factors were examined, including the metal ion photolysis in solution. It becomes clear that as electron scavengers of TiO2 and WO3, Fe(3+) is better than Cu(2+), while they are better than O2. We propose that Fe(3+) recycle occurs through H2O2, photogenerated from TiO2, not from WO3, while Cu(2+) regeneration on a moderate photocatalyst is through the dissolved O2 in water. Copyright © 2013. Published by Elsevier B.V.

  15. Self-sacrificial templating synthesis of porous quaternary Cu-Fe-Sn-S semiconductor nanotubes via microwave irradiation.

    Science.gov (United States)

    Ai, Lunhong; Jiang, Jing

    2012-12-14

    Uniform quaternary Cu(2)FeSnS(4) (CITS) nanotubes of outer diameter 400-800 nm and thickness 100-200 nm have been synthesized for the first time by a simple, rapid and easily scaled-up microwave nonaqueous route using benzyl alcohol as the microwave absorbing solvent. An interesting in situ generated one-dimensional Cu(Tu)Cl nanorod acting as a self-sacrificial template was crucial for the formation of the well-defined CITS nanotubes. Based on the designed time-dependent experiments, a formation mechanism for the CITS nanotubes was also proposed. The resulting CITS nanotubes had a strong absorption in the visible region with a bandgap of 1.71 eV that was optimal for photovoltaic applications. Our study provided a microwave nonaqueous route generally applicable for the synthesis of quaternary chalcogenide semiconductor nanotubes.

  16. Determination of soil micronutrients (Fe, Cu, Mn, B) extracted by Mehlich 3 using MP-AES

    Science.gov (United States)

    Krebstein, Kadri; Tõnutare, Tõnu; Rodima, Ako; Kõlli, Raimo; Künnapas, Allan; Rebane, Jaanus; Penu, Priit; Vennik, Kersti; Soobik, Liina

    2015-04-01

    The total concentration of micronutrients in soils is not a good predictor of its bioavailability and solubility. Therefore, during the decades several methods for the determination of plant availability and extractable fraction of micro- and macronutrients in soil were developed. Among several methods Mehlich 3 is the most appropriate due to its suitability for extracting soil micro- and macronutrients simultaneously. The AAS (atomic absorption spectroscopic) and ICP (inductively coupled plasma) methods are widely used for the analysis of microelements today. In 2011 the third method was added to this list with the appearance of the microwave plasma atomic emission spectrometer (MP-AES). This multielemental analytical equipment has a high potential in the soil analysis. Up to now there have been made some experiments for the use of MP-AES in soil and geological material analysis. But there is no information about the analysis of soil micronutrients extracted according to Mehlich 3 method and determined with the MP-AES. Due to the differences in atomization conditions the different emission and absorption lines are used in different instrumental methods. Therefore it is very important to choose the most suitable emission lines and the best atomization conditions. From the analytical viewpoint it is important to get coincidental results with other instrumental methods and from the agronomical point of view it is important to know the difference between AAS and ICP methods. For the experiment 51 soil samples were used. The samples were collected from A horizons of agricultural lands. The pH range was from 4.7 to 7.5 and organic matter content from 1.4 to 7.8%. The content of Mehlich 3 extractable micronutrients was determined using ICP and MP instrumental methods. The micronutrient contents ranged as follows: Fe - from 170 to 470 mg kg-1, Mn - from 5 to 190 mg kg-1, Cu - from 0.3 to 4.5 mg kg-1, B - from 0.2 to 2.1 mg kg-1. The optimal instrumental settings for iron

  17. The Effect of the Redox Potential of Aqua Regia and Temperature on the Au, Cu, and Fe Dissolution from WPCBs

    Directory of Open Access Journals (Sweden)

    Heini Elomaa

    2017-09-01

    Full Text Available Constant growth in waste electrical and electronic equipment (WEEE levels necessitates the development of new, commercially viable recycling processes. Waste printed circuit boards (WPCBs are a sub-group of WEEE that are of increasing interest due to their relatively high level of valuable metal content including Au, Ag, and platinum group metals (PGMs. Currently, precious metals like gold are mainly recycled from WEEE streams through copper smelting/refining; however, the possibility to peel gold from WPCBs prior to smelting, could offer advantages for recycling. In this study, the suitability of aqua regia for selective or partially selective gold leaching from un-crushed WPCBs was investigated. The redox potential of aqua regia solutions and the dissolution efficiencies of Au, Cu, and Fe from WPCBs were investigated at different temperatures (40–80 °C and concentrations (2–32% in batch leaching tests. The redox potential of aqua regia solution was found to depend on concentration and temperature. It is suggested that Au dissolution in aqua regia requires dissolved Cu2+ ions originating from the WPCB material to work. Au extraction (>50% was shown to require a redox potential >700 mV with [Cu2+] > 2500 ppm, as a potential >850 mV alone was insufficient without cupric ions. Significant amounts of Au and Cu could be dissolved with only minor Fe dissolution at ≥8% aqua regia at 80 °C. Results suggest that leaching of uncrushed WPCBs in 8% aqua regia (T = 80 °C can provide the opportunity for partial Au recovery prior to further processing.

  18. Long-range magnetic order and spin-lattice coupling in delafossite CuFeO2

    Science.gov (United States)

    Eyert, Volker; Frésard, Raymond; Maignan, Antoine

    2008-08-01

    The electronic and magnetic properties of the delafossite CuFeO2 are investigated by means of electronic structure calculations. They are performed using density functional theory in the generalized gradient approximation, as well as the new full-potential augmented spherical wave method. The calculations reveal three different spin states at the iron sites. Using for the first time the experimentally determined low-temperature crystal structure, we find long-range antiferromagnetic ordering in agreement with experiment. In addition, our calculations show that nonlocal interactions as covered by the generalized gradient approximation lead to a semiconducting ground state.

  19. Competing mechanisms for ordering tendencies in BCC CuAuZn{sub 2} and FCC AuFe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, D.D.; Althoff, J.D. [Sandia National Labs., Livermore, CA (United States); Staunton, J.B.; Ling, M.F. [Warwick Univ., Coventry (United Kingdom). Dept. of Physics; Pinski, F.J. [Cincinnati Univ, OH (United States). Dept. of Physics

    1995-07-01

    We have briefly discussed the ASRO (atomic short-range order) in AuFe and CuAuZn{sub 2}. General points are that (1) we have implemented a first-principles theory of ASRO in N-component alloys which allows determination of the electronic origins of said ASRO; (2) such calculations can provide much information on the high- and (sometimes) low-temperature alloys; and (3) this approach has identified the origin for the novel special-point ASRO in AuFe. Displacement effects, i.e., non-rigid lattice effects, as well as the other contributions beyond band-energy, are being incorporated into the multicomponent alloy calculations. Such improvements will allow us to investigate other alloys, where charge effects may play a role, to ``design`, for example, higher temperature intermetallics through alloying.

  20. Lateral electric-field control of giant magnetoresistance in Co/Cu/Fe/BaTiO{sub 3} multiferroic heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Savitha Pillai, S.; Kojima, H.; Itoh, M.; Taniyama, T., E-mail: taniyama.t.aa@m.titech.ac.jp [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama 226-8503 (Japan)

    2015-08-17

    We report lateral electric-field-driven sizable changes in the magnetoresistance of Co/Cu/Fe tri-layered wires on BaTiO{sub 3} single crystal. While the observed change is marginal in the tetragonal phase of BaTiO{sub 3}, it reaches over 40% in the orthorhombic and rhombohedral phases with an electric field of 66 kV/cm. We attribute it to possible electric-field-induced variations of the spin-dependent electronic structures, i.e., spin polarization, of the Fe via interfacial strain transfer from BaTiO{sub 3}. The contrasting results for the different phases of BaTiO{sub 3} are discussed, associated with the distinct aspects of the ferroelectric polarization switching processes in each phase.

  1. Lateral electric-field control of giant magnetoresistance in Co/Cu/Fe/BaTiO3 multiferroic heterostructure

    Science.gov (United States)

    Savitha Pillai, S.; Kojima, H.; Itoh, M.; Taniyama, T.

    2015-08-01

    We report lateral electric-field-driven sizable changes in the magnetoresistance of Co/Cu/Fe tri-layered wires on BaTiO3 single crystal. While the observed change is marginal in the tetragonal phase of BaTiO3, it reaches over 40% in the orthorhombic and rhombohedral phases with an electric field of 66 kV/cm. We attribute it to possible electric-field-induced variations of the spin-dependent electronic structures, i.e., spin polarization, of the Fe via interfacial strain transfer from BaTiO3. The contrasting results for the different phases of BaTiO3 are discussed, associated with the distinct aspects of the ferroelectric polarization switching processes in each phase.

  2. Local X-ray magnetic circular dichroism study of Fe/Cu(111) using a tunneling smart tip

    Energy Technology Data Exchange (ETDEWEB)

    DiLullo, Andrew; Shirato, Nozomi; Cummings, Marvin [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Kersell, Heath; Chang, Hao [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Ohio University, Athens, OH 45701 (United States); Rosenmann, Daniel; Miller, Dean; Freeland, John W. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Hla, Saw-Wai [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Ohio University, Athens, OH 45701 (United States); Rose, Volker, E-mail: vrose@anl.gov [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2016-01-28

    A tunneling smart tip of a synchrotron X-ray scanning tunneling microscope provides simultaneously localized topographic, elemental and magnetic information. Localized spectroscopy with simultaneous topographic, elemental and magnetic information is presented. A synchrotron X-ray scanning tunneling microscope has been employed for the local study of the X-ray magnetic circular dichroism at the Fe L{sub 2,3}-edges of a thin iron film grown on Cu(111). Polarization-dependent X-ray absorption spectra have been obtained through a tunneling smart tip that serves as a photoelectron detector. In contrast to conventional spin-polarized scanning tunneling microscopy, X-ray excitations provide magnetic contrast even with a non-magnetic tip. Intensity variations in the photoexcited tip current point to chemical variations within a single magnetic Fe domain.

  3. The Effects of Fe-Particles on the Tensile Properties of Al-Si-Cu Alloys

    Directory of Open Access Journals (Sweden)

    Anton Bjurenstedt

    2016-12-01

    Full Text Available The effect of Fe-rich particles has been a topic for discussion in the aluminum casting industry because of the negative impact they exert on the mechanical properties. However, there are still contradictions on the effects of various morphologies of Fe-particles. In this study, microstructural characterization of tensile tested samples has been performed to reveal how unmodified and modified Fe-rich particles impact on the tensile behavior. Analysis of additions of Fe modifiers such as Mn and Cr, showed higher amounts of primary Fe-rich particles (sludge with increased porosity and, as result, degraded tensile properties. From the fracture analysis of tensile tested hot isostatic pressed (HIPed samples it could be concluded that the mechanical properties were mainly governed by the Fe-rich particles, which were fracturing through cleavage, not by the porosity.

  4. Experimental investigation of off-stoichiometry and 3d transition metal (Mn, Ni, Cu-substitution in single-crystalline FePt thin films

    Directory of Open Access Journals (Sweden)

    Takuya Ono

    2016-05-01

    Full Text Available In L10 (fct-FePt thin films, both tuning Fe and Pt concentrations and substitution with third-metal were studied for magnetic characteristic optimization. We investigated single-crystalline FePt-X (X = Mn, Ni, Cu thin films grown epitaxially on MgO(001 substrates at a substrate temperature of 350  °C by changing Fe, Pt, and X contents, and explored the effects of off-stoichiometry and 3d-metal-substitution. The magnetic moment per atom (m of FePt-X films as a function of the effective number of valence electrons (neff in 3d metal sites follows the Slater-Pauling-type trend, by which m decreases by the neff deviation from neff = 8, independently of the X metal and the Pt concentration. The magnetic anisotropy (Ku exhibits neff dependence similar to m. This trend was almost independent of the Pt concentration after compensation using the theoretical prediction on the relation between Ku and Fe/Pt concentrations. Such a trend has been proved for stoichiometric FePt-X films, but it was clarified as robust against off-stoichiometry. The compensated Ku ( K u comp of FePt-Mn and FePt-Cu followed a similar trend to that predicted by the rigid-band model, although the K u comp of the FePt-Mn thin films dropped more rapidly than the rigid band calculation. However, it followed the recent first-principles calculation.

  5. Effect of mineral-enriched diet and medicinal herbs on Fe, Mn, Zn, and Cu uptake in chicken

    Directory of Open Access Journals (Sweden)

    Stef Ducu

    2012-03-01

    Full Text Available Abstract Background The goal of our study was to evaluate the effects of different medicinal herbs rich in polyphenol (Lemon balm, Sage, St. John's wort and Small-flowered Willowherb used as dietary supplements on bioaccumulation of some essential metals (Fe, Mn, Zn and Cu in different chicken meats (liver, legs and breast. Results In different type of chicken meats (liver, legs and breast from chickens fed with diets enriched in minerals and medicinal herbs, beneficial metals (Fe, Mn, Zn and Cu were analysed by flame atomic absorption spectrometry. Fe is the predominant metal in liver and Zn is the predominant metal in legs and breast chicken meats. The addition of metal salts in the feed influences the accumulations of all metals in the liver, legs and breast chicken meat with specific difference to the type of metal and meat. The greatest influences were observed in legs meat for Fe and Mn. Under the influence of polyphenol-rich medicinal herbs, accumulation of metals in the liver, legs and breast chicken meat presents specific differences for each medicinal herb, to the control group that received a diet supplemented with metal salts only. Great influence on all metal accumulation factors was observed in diet enriched with sage, which had significantly positive effect for all type of chicken meats. Conclusions Under the influence of medicinal herbs rich in different type of polyphenol, accumulation of metals in the liver, legs and breast chicken meat presents significant differences from the group that received a diet supplemented only with metal salts. Each medicinal herb from diet had a specific influence on the accumulation of metals and generally moderate or poor correlations were observed between total phenols and accumulation of metals. This may be due to antagonism between metal ions and presence of other chelating agents (amino acids and protein from feeding diets which can act as competitor for complexation of metals and influence

  6. Microstructure, magnetic and magnetoimpedance properties in electrodeposited NiFe/Cu and CoNiFe/Cu wire with thiourea additive in plating bath

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Amaresh Chandra, E-mail: amar@phy.iitkgp.ernet.in [Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721302 (India); Department of Physics, IIIT-Basar, Rajiv Gandhi University of Knowledge Technologies, Andhra Pradesh 504107 (India)

    2012-03-15

    Magnetic thin films of NiFe and CoNiFe alloys were electrodeposited from three different deposition baths onto copper wires of 100-{mu}m diameter. The magnetic and magnetoimpedance (MI) properties of the samples along with their microstructure were investigated as a function of thiourea additive concentrations (C{sub T}) in the plating bath. For all intermediate frequencies, the MI ratio increased with thiourea concentration in plating bath up to a critical concentration of 80 mg/l and then decreased considerably. The change in MI with thiourea concentration in electrodeposition bath was attributed to the grain size reducing action of thiourea, which in turn enhances the soft magnetic properties of the films. At higher concentration of thiourea, the sulfur inclusion increased the magnetic softness and MI value enhanced considerably. The origin of MI lies in the combined effect of domain wall motion and spin rotation, which contributes to permeability. Inductance spectroscopy (IS) was used to evaluate the magnetic characteristic of the samples by modeling coated wires in terms of equivalent electrical circuit; namely parallel LR (inductance and resistance) circuit in series with series LR circuit. The domain wall motion was found to be greatly affected by thiourea addition in the bath, which was revealed through the study of variation of these circuit parameters. The domain wall motion thereby affects the magnetic softness of samples, which is reflected in the MI enhancement.

  7. Fe{sub 3}O{sub 4}/CuO/ZnO/Nano graphene platelets (Fe{sub 3}O{sub 4}/CuO/ZnO/NGP) composites prepared by sol-gel method with enhanced sonocatalytic activity for the removal of dye

    Energy Technology Data Exchange (ETDEWEB)

    Hendry, Tju; Taufik, Ardiansyah; Saleh, Rosari, E-mail: rosari.saleh@gmail.com, E-mail: rosari.saleh@ui.ac.id [Departemen Fisika, Fakultas MIPA-Universitas Indonesia, 16424 Depok (Indonesia); Integrated Laboratory of Energy and Environment, Fakultas MIPA-Universitas Indonesia, 16424 Depok (Indonesia)

    2016-04-19

    In this study, an attempt has been made to synthesize nanographene platelets coupled with Fe3O4/CuO/ZnO (Fe3O4/CuO/ZnO/NGP) with various ZnO loadings using a two step methods, sol-gel followed by hydrothermal method. Characterization was carried out by X-ray diffraction, energy-dispersive X-ray spectroscopy and vibrating sample magnetometer. The sonocatalytic performance was evaluated by degradation of methylene blue under ultrasonic irradiation.The Fe3O4/CuO/ZnO/NGP showed superior sonocatalytic activity than the Fe3O4/CuO/ZnO materials. They also showed high stability and can be easily separated from the reaction system for recycling process.

  8. CuFe2O4 magnetic heterogeneous nanocatalyst: Low power sonochemical-coprecipitation preparation and applications in synthesis of 4H-chromene-3-carbonitrile scaffolds.

    Science.gov (United States)

    Rajput, Jaspreet Kaur; Arora, Priya; Kaur, Gagandeep; Kaur, Manpreet

    2015-09-01

    The paper presents the synthesis and catalytic activity of CuFe2O4 nanoparticles. The CuFe2O4 nanoparticles have been prepared by sonochemical route under low power ultrasonic irradiation (UI) and using silent stirring at room temperature only (ST) along with co-precipitation method, without using any additive/capping agent. The synthesized magnetic nanoparticles were successfully used and compared for the synthesis of 4H-chromene-3-carbonitrile derivatives. The CuFe2O4 nanoparticles obtained by sonochemical route exhibit higher catalytic activity because of small size (0.5-5 nm), high surface area (214.55 m(2)/g), high thermal stability up to 700°C, recyclability and reusability due to its magnetic characteristics than CuFe2O4 nanoparticles obtained by room temperature silent stirring. The synthesized CuFe2O4 nanoparticles were characterized by FT-IR, SEM-EDX, HR-TEM, XRD, TGA/DTA/DTG, BET, VSM techniques. The present method is of great interest due to its salient features such as environmentally compatible, efficient, short reaction time, chemoselectivity, high yield, cheap, moisture insensitive, green and recyclable catalyst which make it sustainable protocol. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Heterogeneous photo-Fenton processes using graphite carbon coating hollow CuFe2O4 spheres for the degradation of methylene blue

    Science.gov (United States)

    Guo, Xiaojun; Wang, Kebai; Li, Dai; Qin, Jiabin

    2017-10-01

    The novel graphite carbon coating hollow CuFe2O4 spheres were fabricated through solvothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectra, etc. The catalytic performance of the graphite carbon coating hollow CuFe2O4 spheres was evaluated in photo-Fenton-like degradation of methylene blue (MB) using H2O2 as a green oxidant under light irradiation (λ > 400 nm). The results demonstrated that the hollow CuFe2O4 spheres with graphite carbon coating exhibited superior catalytic activity. In the preparation process of catalyst, the addition of glucose was very important to its catalytic performance. Photoresponse analysis of the typical samples proved that CuFe2O4@graphite carbon core-shell hollow spheres possessed excellent photocurrent response and lower electrochemical impedance. In addition, a possible mechanism for photocatalytic degradation of MB had been presumed. Moreover, after five regeneration cycles, the graphite carbon coating hollow CuFe2O4 spheres still exhibited better properties.

  10. Distribution of Cd, Cu, Fe, Mn, Pb and Zn in selected tissues of juvenile whales stranded in the SE Gulf of California (Mexico).

    Science.gov (United States)

    Ruelas-Inzunza, J; Páez-Osuna, F

    2002-09-01

    With the aim of knowing the concentration and distribution of essential and nonessential metals in selected tissues of whales, analysis of Cd, Cu, Fe, Mn, Pb and Zn were carried out in kidney, liver and muscle of the gray whale Eschrichtius robustus and the sperm whale Physeter catodon. Whales were found stranded in the southeast Gulf of California. Individuals were in a juvenile stage; mean length of whales was 9.3 m for E. robustus and 7 m for P. catodon. Sequence of metal concentrations was Fe>Zn>Cu>Mn>Cd>Pb in E. robustus, and Fe>Zn>Cu>Cd>Mn>Pb in P. catodon. In E. robustus, highest concentrations of Cu, Mn, Pb and Zn (17.2, 19.6, 0.9 and 388 microg g(-1), respectively) were measured in liver, Cd (5.7 microg g(-1)) in kidney and Fe (1009 microg g(-1)) in muscle. In P. catodon, the highest levels of Cu, Fe and Pb (48.6, 5200 and 4.2 microg g(-1), respectively) were found in liver, Cd and Zn (94 and 183 microg g(-1)) in kidney and Mn (8 microg g(-1)) in muscle. Metal concentrations reported here were not considered to contribute to the stranding of specimens.

  11. Combustion synthesized copper-ion substituted FeAl2O4 (Cu0.1Fe0.9Al2O4): A superior catalyst for methanol steam reforming compared to its impregnated analogue

    Science.gov (United States)

    Maiti, Sayantani; Llorca, Jordi; Dominguez, Montserrat; Colussi, Sara; Trovarelli, Alessandro; Priolkar, Kaustubh R.; Aquilanti, Giuliana; Gayen, Arup

    2016-02-01

    A series of copper ion substituted MAl2O4 (M = Mg, Mn, Fe and Zn) spinels is prepared by a single step solution combustion synthesis (SCS) and tested for methanol steam reforming (MSR). The copper ion substituted Cu0.1Fe0.9Al2O4 appears to be the most active, showing ∼98% methanol conversion at 300 °C with ∼5% CO selectivity at GHSV = 30,000 h-1 and H2O:CH3OH = 1.1. The analogous impregnated catalyst, CuO (10 at%)/FeAl2O4, is found to be much less active. These materials are characterized by XRD, H2-TPR, BET, HRTEM, XPS and XANES analyses. Spinel phase formation is highly facilitated upon Cu-ion substitution and Cu loading beyond 10 at% leads to the formation of CuO as an additional phase. The ionic substitution of copper in FeAl2O4 leads to the highly crystalline SCS catalyst containing Cu2+ ion sites that are shown to be more active than the dispersed CuO nano-crystallites on the FeAl2O4 impregnated catalyst, despite its lower surface area. The as prepared SCS catalyst contains also a portion of copper as Cu1+ that increases when subjected to reforming atmosphere. The MSR activity of the SCS catalyst decreases with time-on-stream due to the sintering of catalyst crystallites as established from XPS and HRTEM analyses.

  12. Heme/Cu/O2 reactivity: change in FeIII-(O2 2-)-CuII unit peroxo binding geometry effected by tridentate copper chelation.

    Science.gov (United States)

    Kim, Eunsuk; Shearer, Jason; Lu, Shen; Moënne-Loccoz, Pierre; Helton, Matthew E; Kaderli, Susan; Zuberbühler, Andreas D; Karlin, Kenneth D

    2004-10-13

    A new heme-peroxo-copper complex structural type with mu-eta2:eta2 peroxo ligation has been generated utilizing a heterobinucleating ligand with bis(2-(2-pyridyl)ethyl)amine tridentate chelate for copper. Oxygenation of [(2L)FeIICuI]+ (1) at -80 degrees C in CH2Cl2/6%EtCN, 1 (lambdamax, 426, 530 nm) produces [(2L)FeIII-(O22-)-CuII)]+ (3) (lambdamax, 419, 488, 544, 575 nm). Stopped-flow kinetic/spectroscopic probing reveals that a superoxo complex, [(2L)FeIII-(O2-)...CuI(NCEt)]+ (2) (lambdamax = 544 nm), initially forms, k1 = 5.23 +/- 0.09 x 104 M-1 s-1 (-105 degrees C). Subsequent intramolecular reaction of the copper(I) ion in 2 occurs with k2 = 2.74 +/- 0.04 x 101 s-1 (-105 degrees C), producing 3. Resonance Raman spectroscopy (rR) confirms the peroxo assignment for 3; nu(O-O) = 747 cm-1 (Delta(18O2) = -40 cm-1). In an 16O-18O mixed isotope experiment a single band is observed at 730 cm-1. The low nu(O-O) value and the absence of a splitting of the 730 cm-1 band are indicative of a symmetrical binding of the peroxide group in a side-on mu-eta2:eta2 geometry. This conclusion is supported by X-ray absorption spectroscopy on 3. Copper K-edge EXAFS indicates a five-coordinate metal center: 2 N, 2.028(7) A; 2 O, 1.898(7) A; 1 N, 2.171(12) A. An outer-sphere Fe scatterer is found at 3.62(1) A. The iron center K-edge EXAFS fits to either a five- or six-coordinate metal center: 4 N(pyrrole), approximately 2.1 A; 1,2 O, approximately 1.9 A. A preedge feature (Fe(1s) --> Fe(3d) transition) at 7113.2(2) eV resembles that obtained for a eta2-peroxo ferric heme complex, being weaker and at approximately 1.5 eV lower energy than those found in five-coordinate (P)FeIII-X (in C4v symmetry) complexes. Arguments based on rR properties of relevant peroxo compounds also effectively point to the copper(II) ion in 3 as being side-on bound, leading to the very low O-O stretching frequency observed in comparison to those of heme-peroxo species or heme-peroxo-copper complexes with a

  13. Structural and hyperfine evolution of the (Fe{sub 79}Mn{sub 21}){sub 1-x}Cu{sub x} system under milling time

    Energy Technology Data Exchange (ETDEWEB)

    Mizrahi, M., E-mail: mizrahi@fisica.unlp.edu.a [Departamento de Fisica, Facultad de Ciencias Exactas UNLP, IFLP-CONICET. C.C. 67 1900 La Plata (Argentina); Cabrera, A.F.; Desimoni, J. [Departamento de Fisica, Facultad de Ciencias Exactas UNLP, IFLP-CONICET. C.C. 67 1900 La Plata (Argentina)

    2010-04-16

    The evolution with milling time (t{sub m}) of the structural and hyperfine properties of mechanically alloyed (Fe{sub 79}Mn{sub 21}){sub 0.85}Cu{sub 0.15} and (Fe{sub 79}Mn{sub 21}){sub 0.70}Cu{sub 0.30} nominal composition samples are reported. The samples milled during t{sub m} = 1, 3, 6, 9, 12, 15 and 18 h are characterized by X-ray diffraction (XRD) and Moessbauer spectroscopy. From the XRD results two phases are observed, a BCC one corresponding to {alpha}-Fe(Mn, Cu) and a FCC-phase associated to Fe-Mn-Cu solid solution. Moessbauer spectra show complex structure evidencing several Fe environments. Two hyperfine magnetic field distributions were used to reproduce the spectra, a high magnetic field interaction ascribed to the BCC phase and a low hyperfine magnetic field distribution linked to the FCC solid solution. An increment in the average hyperfine magnetic field (B{sub hf}) and in the isomer shift ({delta}) values of the low hyperfine magnetic field distribution is observed when the milling time increases. All the structural and hyperfine parameters remain without changes after 9 h of milling. Once this stationary regime is archived, the B{sub hf} of the (Fe{sub 79}Mn{sub 21}){sub 0.85}Cu{sub 0.15} sample resulted higher than that of the (Fe{sub 79}Mn{sub 21}){sub 0.70}Cu{sub 0.30} one.

  14. ‘Venus trapped, Mars transits': Cu and Fe redox chemistry, cellular topography and in situ ligand binding in terrestrial isopod hepatopancreas

    Science.gov (United States)

    Kille, P.; Morgan, A. J.; Powell, K.; Mosselmans, J. F. W.; Hart, D.; Gunning, P.; Hayes, A.; Scarborough, D.; McDonald, I.; Charnock, J. M.

    2016-01-01

    Woodlice efficiently sequester copper (Cu) in ‘cuprosomes' within hepatopancreatic ‘S' cells. Binuclear ‘B’ cells in the hepatopancreas form iron (Fe) deposits; these cells apparently undergo an apocrine secretory diurnal cycle linked to nocturnal feeding. Synchrotron-based µ-focus X-ray spectroscopy undertaken on thin sections was used to characterize the ligands binding Cu and Fe in S and B cells of Oniscus asellus (Isopoda). Main findings were: (i) morphometry confirmed a diurnal B-cell apocrine cycle; (ii) X-ray fluorescence (XRF) mapping indicated that Cu was co-distributed with sulfur (mainly in S cells), and Fe was co-distributed with phosphate (mainly in B cells); (iii) XRF mapping revealed an intimate morphological relationship between the basal regions of adjacent S and B cells; (iv) molecular modelling and Fourier transform analyses indicated that Cu in the reduced Cu+ state is mainly coordinated to thiol-rich ligands (Cu–S bond length 2.3 Å) in both cell types, while Fe in the oxidized Fe3+ state is predominantly oxygen coordinated (estimated Fe–O bond length of approx. 2 Å), with an outer shell of Fe scatterers at approximately 3.05 Å; and (v) no significant differences occur in Cu or Fe speciation at key nodes in the apocrine cycle. Findings imply that S and B cells form integrated unit-pairs; a functional role for secretions from these cellular units in the digestion of recalcitrant dietary components is hypothesized. PMID:26935951

  15. The role of additives in moderating the influence of Fe(III) and Cu(II) on the radiochemical yield of [⁶⁸Ga(DOTATATE)].

    Science.gov (United States)

    Oehlke, Elisabeth; Lengkeek, Nigel A; So Le, Van; Pellegrini, Paul A; Greguric, Ivan; Weiner, Ron

    2016-01-01

    [(68)Ga(DOTATATE)] has demonstrated its clinical usefulness. Both Fe(3+) and Cu(2+), potential contaminants in Gallium-68 generator eluent, substantially reduce the radiochemical (RC) yield of [(68)Ga(DOTATATE)] if the metal/ligand ratio of 1:1 is exceeded. A variety of compounds were examined for their potential ability to reduce this effect. Most had no effect on RC yield. However, addition of phosphate diminished the influence of Fe(3+) by likely forming an insoluble iron salt. Addition of ascorbic acid reduced Cu(2+) and Fe(3+) to Cu(+) and Fe(2+) respectively, both of which have limited impact on RC yields. At low ligand amounts (5 nmol DOTATATE), the addition of 30 nmol phosphate (0.19 mM) increased the tolerance of Fe(3+) from 4 nmol to 10 nmol (0.06 mM), while the addition of ascorbic acid allowed high RC yields (>95%) in the presence of 40 nmol Fe(3+) (0.25 mM) and 100 nmol Cu(2+) (0.63 mM). The effect of ascorbic acid was highly pH-dependant, and gave optimal results at pH 3. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  16. Leaching of rapidly quenched Al65Cu20Fe15 quasicrystalline ribbons

    Indian Academy of Sciences (India)

    2017-12-06

    Dec 6, 2017 ... The Al–Mn QC exhibiting a simple icosahedral (i) symmetry. (Pm35), however the ordered QC was showing face-centred icosahedral (FCI) symmetry (Fm35) reported in annealed. Al–Cu–Fe rapidly solidified alloy [7,8]. A stable (i) Al–Cu–. Fe ternary QC has been discovered, which is a part of the.

  17. Measurement and analysis of distribution coefficients in Fe-Ni alloys containing S and/or P. II - K(Ir), K(Ge), and K(Cu)

    Science.gov (United States)

    Sellamuthu, R.; Goldstein, J. I.

    1985-01-01

    Crystals of Fe-Ni-S-P alloys containing Ir, Ge, and Cu in small amounts were grown by plane front solidification. The electron microprobe was used to measure the compositions of these alloys. The Ir, Ge, and Cu distribution coefficients were determined by an analytical procedure from the composition data. The distribution coefficients of Ir, Ge, and Cu vary from 1.20 to 11.0, 0.75 to 2.1, and 0.06 to 0.84, respectively. K(Ir) and K(Ge) increase and K(Cu) decreases with the S content of the liquid. K(Cu) increases and K(Ir) and K(Ge) decrease with the P content of the liquid. Mathematical expressions have been formulated to relate the Ir, Ge, and Cu distribution coefficients to the S and P contents of the liquid. These distribution coefficients are important to the study of the solidification behavior of iron meteorites.

  18. Effects of dietary copper on organ indexes, tissular Cu, Zn and Fe deposition and fur quality of growing-furring male mink (Mustela vison).

    Science.gov (United States)

    Wu, Xuezhuang; Gao, Xiuhua; Yang, Fuhe

    2015-01-01

    The objectives of this study were to study the effects of different levels of dietary copper on organ indexes, tissular Cu, Zn and Fe deposition and fur quality of mink in the growing-furring periods. One hundred and five standard dark male mink were randomly assigned to seven groups with the following dietary treatments: basal diet with no supplemental Cu (Control); basal diet supplemented with either 6, 12, 24, 48, 96 and 192 mg/kg Cu from copper sulphate, respectively. The colour intensity scores displayed a linear trend (P = 0.057). The spleen Cu concentrations responded in a linear (P  0.10) liver Zn. Our results indicate that Cu plays an important role in the pigmentation in growing-furring mink, and supplemental dietary Cu in growing-furring mink improve hair colour, and copper has limited effects on liver mineral deposition.

  19. Magnetic and electronic studies of Cu{sub 80}Fe{sub 5}Ni{sub 15} granular ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Omari, N., E-mail: nabila_omari@yahoo.fr [LPTA, Université Hassan II—Casablanca, Faculté des Sciences, B.P. 5366 Maârif (Morocco); Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble cedex 9 (France); Lassri, H. [LPMMAT, Université Hassan II—Casablanca, Faculté des Sciences, B.P. 5366 Maârif (Morocco); Fnidiki, A. [Groupe de Physique des Matériaux, UMR CNRS 6634, Faculté des Sciences de Rouen, Site Universitaire du Madrillet, Avenue de l' Université, BP 12, 76801 Saint-Etienne du Rouvray Cedex (France); Abid, M. [LPTA, Université Hassan II—Casablanca, Faculté des Sciences, B.P. 5366 Maârif (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble cedex 9 (France)

    2013-10-15

    Magnetic and electronic properties of granular Cu{sub 80}Fe{sub 5}Ni{sub 15} ribbons are investigated by magnetization measurements and first principle calculations. Magnetization variation versus temperature is found to obey the Bloch law, allowing us to calculate the spin wave stiffness constant D and the exchange constant A from the experimental results. The magnetic experimental results have been interpreted within the framework of random magnetic anisotropy (RMA) model. The results have shown the possibility to extend the application of RMA to the granular ribbons. Some fundamental parameters have been extracted from the approach to saturation magnetization. In addition, self-consistent ab initio calculations, based on Korringa–Kohn–Rostocker (KKR), are performed to investigate both electronic and magnetic properties. These calculations include spin polarized potential within the framework of the Coherent Potential Approximation (CPA). - Highlights: • We have studied the magnetization of the granular Cu{sub 80}Fe{sub 5}Ni{sub 15} ribbons with the spin wave theory. • The magnetic results have been interpreted within the framework of RMA model. • We find that the local anisotropy is about 5×10{sup 5} erg/cm{sup 3} at 5 K. • ab initio calculations are performed to investigate both electronic and magnetic properties.

  20. Effects of oxygen nonstoichiometry on the stability of antiferromagnetic phases of CuFeO2+δ single crystals

    Science.gov (United States)

    Hasegawa, M.; Batrashevich, M. I.; Zhao, T. R.; Takei, H.; Goto, T.

    2001-05-01

    Effects of oxygen nonstoichiometry on stabilities of the antiferromagnetic (AF) phases of CuFeO2 with a delafossite-type structure have been investigated. Temperature dependence of the magnetic susceptibility between 5 and 300 K in 0.1 T parallel to the c axis, and magnetic-field dependence of the magnetization below 40 T parallel to the c axis at 4.2 K are clarified using CuFeO2+δ single crystals with stoichiometry varying from oxygen deficiency (δ=-0.026, -0.061) to oxygen excess (δ=0.14, 0.085). It is found that the stabilities are strongly affected by the oxygen defects, depending on their type, i.e., oxygen deficiency or oxygen excess. The transition temperature between the four-sublattice AF phase (low-temperature AF phase) and the partially disordered phase (high-temperature AF phase) is increased by the oxygen deficiency, whereas it is decreased by the excess oxygen. It should be noted that both types of oxygen defects bring another metamagnetic transition around 23 T. Besides, all metamagnetic transition fields are increased by the oxygen defects. These effects are discussed from the viewpoints of crystal chemistry.

  1. STUDIES REGARDING THE CHELATE-INDUCED HYPERACCUMULATION OF CU AND FE USING LOLIUM PERENNE SPECIES IN MINING AREAS

    Directory of Open Access Journals (Sweden)

    ANCA-DIANA PRICOP

    2009-05-01

    Full Text Available The plant capacity to absorb high amounts of metal for a short period of time is the major factor that influences the efficiency of phytoextraction. The hyperaccumulating plants uptake high amounts in their tissues correlated to the metal concentrations in soil. Chelating agents have the capacity to induce the metal accumulation in biomass. They increase metal bioavailability for plants by releasing the metal in accessible forms. The present study emphasizes that in the case of EDTA use, the obtained biomass is smaller compared to the other variants, showing a lower tolerance to this chelating agent of Lolium perenne species. Cu and Fe phytoextraction by Lolium perenne species is higher in the case of EDTA use. Cu bioaccumulation has higher values in variants with compost-sterile mixture ratio of 1:4 in comparison with Fe. In the case of the best compost-sterile mixture ratio of 1:3 the highest biomass is obtained in all the variants, biosolids’ effect being stronger compared to the chelating agent.

  2. Conductivity enhancement of ion tracks in tetrahedral amorphous carbon by doping with N, B, Cu and Fe

    Energy Technology Data Exchange (ETDEWEB)

    Krauser, J., E-mail: jkrauser@hs-harz.de [Hochschule Harz, University of Applied Sciences, 38855 Wernigerode (Germany); Nix, A.-K., E-mail: anix@gwdg.de [II. Institute of Physics, University of Goettingen, 37077 Goettingen (Germany); Gehrke, H.-G., E-mail: hgehrke1@gwdg.de [II. Institute of Physics, University of Goettingen, 37077 Goettingen (Germany); Hofsaess, H., E-mail: hans.hofsaess@phys.uni-goettingen.de [II. Institute of Physics, University of Goettingen, 37077 Goettingen (Germany); Trautmann, C., E-mail: C.Trautmann@gsi.de [Helmholtzzentrum fuer Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Weidinger, A., E-mail: alois.weidinger@berlin.de [Helmholtz-Zentrum Berlin GmbH, 14109 Berlin (Germany)

    2012-02-01

    Conducting ion tracks are formed when high-energy heavy ions (e.g. 1 GeV Au) pass through tetrahedral amorphous carbon (ta-C). These nanowires with a diameter of about 8 nm are embedded in the insulating ta-C matrix and of interest for various nanotechnological applications. Usually the overall conductivity of the tracks and the current/voltage characteristics (Ohmic or non-Ohmic) vary strongly from track to track, even when measured on the same sample, indicating that the track formation is neither complete nor homogeneous. To improve the track conductivity, doping of ta-C with N, B, Cu, or Fe is investigated. Beneficial changes in track conductivity after doping compete with a conductivity increase of the surrounding matrix material. Best results are achieved by incorporation of 1 at.% Cu, while for different reasons, the improvement of the tracks remains moderate for N, B, and Fe doping. Conductivity enhancement of the tracks is assumed to develop during the ion track formation process by an increased number of localized states which contribute to the current transport.

  3. Thin and Flexible Fe-Si-B/Ni-Cu-P Metallic Glass Multilayer Composites for Efficient Electromagnetic Interference Shielding.

    Science.gov (United States)

    Zhang, Jijun; Li, Jiawei; Tan, Guoguo; Hu, Renchao; Wang, Junqiang; Chang, Chuntao; Wang, Xinmin

    2017-11-20

    Thin and flexible materials that can provide efficient electromagnetic interference (EMI) shielding are urgently needed, especially if they can be easily processed and withstand harsh environments. Herein, layer-structured Fe-Si-B/Ni-Cu-P metallic glass composites have been developed by simple electroless plating Ni-Cu-P coating on commercial Fe-Si-B metallic glasses. The 0.1 mm-thick composite shows EMI shielding effectiveness of 40 dB over the X-band frequency range, which is higher than those of traditional metals, metal oxides, and their polymer composites of larger thickness. Most of the applied electromagnetic waves are proved to be absorbed rather than bounced back. This performance originates from the combination of a superior soft magnetic property, excellent electrical conductivity, and multiple internal reflections from multilayer composites. In addition, the flexible composites also exhibit good corrosion resistance, high thermal stability, and excellent tensile strength, making them suitable for EMI shielding in harsh chemical or thermal environments.

  4. Cu-Fe-S Nanocrystals Exhibiting Tunable Localized Surface Plasmon Resonance in the Visible to NIR Spectral Ranges.

    Science.gov (United States)

    Gabka, Grzegorz; Bujak, Piotr; Ostrowski, Andrzej; Tomaszewski, Waldemar; Lisowski, Wojciech; Sobczak, Janusz W; Pron, Adam

    2016-07-05

    Cu-Fe-S nanocrystals exhibiting a strong localized surface plasmon resonance (LSPR) effect were synthesized for the first time. The elaborated reproducible preparation procedure involved copper(II) oleate, iron(III) stearate, and sulfur powder dissolved in oleylamine (OLA) as precursors. The wavelength of the plasmonic resonance maximum could be tuned by changing the Cu/Fe ratio in the resulting nanocrystals, being the most energetic for the 1:1 ratio (486 nm) and undergoing a bathochromic shift to ca. 1200 nm with an increase to 6:1. LSPR could also be observed in nanocrystals prepared from the same metal precursors and sulfur powder dissolved in 1-octadecene (ODE), provided that the sulfur precursor was taken in excess. Detailed analysis of the reaction mixture by chromatographic techniques, supplemented by mass spectrometry and (1)H NMR spectroscopy enabled the identification of the true chemical nature of the sulfur precursor in S/OLA, namely, (C18H35NH3(+))(C18H35NH-S8(-)), a reactive product of the reduction of elemental sulfur by the amine groups of OLA. In the case of the S/ODE precursor, the true precursors are much less reactive primary or secondary thioethers and dialkyl polysulfides.

  5. Influence of magnetic field on the thermal conductivity of the water based mixed Fe3O4/CuO nanofluid

    Science.gov (United States)

    Ebrahimi, Samaneh; Saghravani, Seyed Fazlolah

    2017-11-01

    Mixed Fe3O4/CuO nanofluid was selected and the role of external magnetic field with strength up to 0.2 T was studied on the thermal conductivity of the considered nanofluid with different basic parameters such as nanoparticle concentration and temperature of the base fluid. Thermal conductivity was measured using hot wire technique. Also the magnetic field applied uniformly to the nanofluid system regarding to the different situations of the field strength and weight percent of the both containing Fe3O4 and CuO nanoparticles. We found that the thermal conductivity of the pure and mixed Fe3O4 with CuO nanoparticle has significant enhancement at presence of the external magnetic field. However the rate of the thermal conductivity growth is strongly correlated with the magnetic field strength which is applied uniformly to the system. More results including measurement technique and conclusions are described in details at the context.

  6. The structure and physical properties of CuMPd{sub 6} (M = Ti, V, Mn and Fe) ternary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ziya, A.B. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan)], E-mail: amerziya@gmail.com; Takahashi, M.; Ohshima, K. [Institute of Materials Science, University of Tsukuba, Tsukuba 305-8573 (Japan)

    2009-06-24

    In situ X-ray diffraction and magnetic susceptibility measurements were performed to determine the structure, thermal and magnetic properties of the ternary alloys CuMPd{sub 6} (M = Ti, V, Mn and Fe). The X-ray diffraction experiments of the polycrystalline specimens annealed at 1273 K have shown that a single phase (A1-type face-centered cubic (fcc) structure) is formed at this stoichiometric composition up to a temperature of 1178 K. The integrated intensity data obtained from the diffraction experiments were utilized to determine the lattice parameters, Debye temperatures ({theta}{sub D}), the mean linear thermal expansion (MLTE) and the coefficients of thermal expansion ({alpha}(T)). The lattice parameters showed a positive deviation from the Vegard's law, whereas the Debye temperatures were found to be of the same order as for CuPd{sub 3} alloy. The contribution of the static displacements to the temperature factors was found to be nearly zero for the four alloys. The linear thermal expansion follows the classical Grueneisen relationship in these alloys. The trend of magnetic properties in these alloys was observed to be similar to that for CuMPt{sub 6} alloys (see text) i.e. paramagnetic - spin glass - ferromagnetic with the increasing atomic number of the metal M. The results have been discussed by comparing with those given in literature.

  7. Efficient solar light-driven degradation of Congo red with novel Cu-loaded Fe3O4@TiO2 nanoparticles.

    Science.gov (United States)

    Arora, Priya; Fermah, Alisha; Rajput, Jaspreet Kaur; Singh, Harminder; Badhan, Jigyasa

    2017-08-01

    In this work, Cu-loaded Fe3O4@TiO2 core shell nanoparticles were prepared in a single pot by coating of TiO2 on Fe3O4 nanoparticles followed by Cu loading. X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), thermogravimetric analysis (TGA), Brunauer-Emmett- Teller (BET), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), and valence band X-ray photoelectron spectroscopy (VB XPS) techniques were used for characterization of as prepared nanoparticles. Synergism between copper and titania was evaluated by studying the solar light-driven photodegradation of Congo red dye solution in the presence of Fe3O4@TiO2 nanoparticles on one side and Cu-loaded Fe3O4@TiO2 nanoparticles on the other side. The latter performed better than the former catalyst, indicating the enhanced activity of copper-loaded catalyst. Further photodegradation was studied by three means, i.e., under ultraviolet (UV), refluxing, and solar radiations. Cu-loaded Fe3O4@TiO2 enhanced the degradation efficiency of Congo red dye. Thus, Cu act possibly by reducing the band gap of TiO2 and widening the optical response of semiconductor, as a result of which solar light could be used to carry out photocatalysis. Graphical abstract Photodegradation of congo red over Cu-loaded Fe3O4@TiO2 nanoparticles.

  8. Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry for the determination of Cr, Fe, Cu, Zn and Se in cereals

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Shih-Yi [Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China); Jiang, Shiuh-Jen, E-mail: sjjiang@faculty.nsysu.edu.tw [Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China); Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, Kaohsiung 80708, Taiwan (China); Sahayam, A.C. [National Centre for Compositional Characterisation of Materials (CCCM), Hyderabad (India)

    2014-11-01

    Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to determine Cr, Fe, Cu, Zn and Se in several cereal samples. Thioacetamide was used as the modifier to enhance the ion signals. The background ions at the masses of interest were reduced in intensity significantly by using 1.0 mL min{sup −1} methane (CH{sub 4}) as reaction cell gas in the dynamic reaction cell (DRC). Since the sensitivities of Cr, Fe, Cu, Zn and Se in different matrices were quite different, standard addition and isotope dilution methods were used for the determination of Cr, Fe, Cu, Zn and Se in these cereal samples. The method detection limits estimated from standard addition curves were about 1, 10, 4, 12 and 2 ng g{sup −1} for Cr, Fe, Cu, Zn and Se, respectively, in original cereal samples. This procedure has been applied to the determination of Cr, Fe, Cu, Zn and Se whose concentrations are in μg g{sup −1} (except Cr and Se) in standard reference materials (SRM) of National institute of standards and technology (NIST), NIST SRM 1568a Rice Flour and NIST SRM 1567a Wheat Flour and two cereal samples purchased from a local market. The analysis results of reference materials agreed with certified values at 95% confidence level according to Student's T-test. The results for the real world cereal samples were also found to be in good agreement with the pneumatic nebulization DRC ICP-MS results of the sample solutions. - Highlights: • Determination of Cr, Fe, Cu, Zn and Se in cereal samples • Ultrasonic slurry sampling in combination with DRC-ICP-MS • Better sensitivity with thioacetamide modifier in ETV • Decreased sample preparation time with solid sampling • Validation with NIST SRM 1568a Rice Flour and NIST SRM 1567a Wheat Flour.

  9. Feasibility of dispersive liquid–liquid microextraction for extraction and preconcentration of Cu and Fe in red and white wine and determination by flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Seeger, Tassia S.; Rosa, Francisco C.; Bizzi, Cezar A.; Dressler, Valderi L.; Flores, Erico M.M.; Duarte, Fabio A., E-mail: fabioand@gmail.com

    2015-03-01

    A method for extraction and preconcentration of Cu and Fe in red and white wines using dispersive liquid–liquid microextraction (DLLME) and determination by flame atomic absorption spectrometry (F AAS) was developed. Extraction was performed using sodium diethyldithiocarbamate as chelating agent and a mixture of 40 μL of 1,2-dichlorobenzene (extraction solvent) and 900 μL of methanol (dispersive solvent). Some parameters that influencing the extraction efficiency such as pH (2 to 5), concentration of chelating agent (0 to 2%), effect of salt addition (0 to 10%), number of washing steps (1 to 4) and centrifugation time (0 to 15 min) were studied. Accuracy was evaluated after microwave-assisted digestion in closed vessels and analytes were determined by inductively coupled plasma optical emission spectrometry. Agreement with the proposed method ranged from 91 to 110 and from 89 to 113% for Cu and Fe, respectively. Calibration of F AAS instrument was performed using analyte addition method and limits of detection were 6.3 and 2.4 μg L{sup −1} for Cu and Fe, respectively. The proposed method was applied for the determination of Cu and Fe in five samples of red wine and three samples of white wine, with concentration ranging from 21 to 178 μg L{sup −1} and from 1.38 to 3.74 mg L{sup −1}, respectively. - Highlights: • Determination of Cu and Fe in wine using DLLME and F AAS • High preconcentration factors and low LODs were achieved. • Alternative method for the determination of Cu and Fe in wine for routine analysis.

  10. Effects of Pd substitution on the thermoelectric and electronic properties of delafossite Cu1-xPdxFeO2 (x=0.01, 0.03 and 0.05)

    Science.gov (United States)

    Ruttanapun, Chesta

    2014-07-01

    Cu(1-x)Pd(x)FeO2 (x=0.01, 0.03 and 005) delafossite was prepared by solid state reactions and was calcined/sintered at 1050 °C. The effect of Pd2+ substitution for the Cu1+ sites on the thermoelectric and electronic properties of Cu(1-x)Pd(x)FeO2 were investigated. The crystal structure, oxygen decomposition, thermoelectric and electronic properties were characterized by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS), Seebeck coefficient, electrical conductivity and thermal conductivity measurements. The characterization showed that Cu(1-x)Pd(x)FeO2 formed a hexagonal delafossite structure with R3-m symmetry. The existence of Pd2+, Cu1+, Cu2+, Fe3+, Fe4+ and O was revealed from the XPS results. Confirmation of Pd2+ substitution for the Cu1+ sites occurred by increasing the c-axis in the lattice parameter with a Pd content. The O content intercalated at the center of the triangular Cu acted as a support to produce Cu2+ ions and was reduced with an increasing Pd content. The mixed valencies of Cu1+/Cu2+ and Cu1+/Pd2+ in the Cu layer changed the electrical conductivity and the Fe3+/Fe4+ mixed valencies in the FeO6 layer caused the Seebeck coefficient to increase. Both the electrical conductivity and Seebeck coefficient for Pd contents of x=0.01 and 0.03 were higher than that of non-doped CuFeO2. The low thermal conductivity of Cu(1-x)Pd(x)FeO2 resulted from the substitution of Pd, which has a large atomic mass, into structure. The Jonker plot indicated that the electronic properties displayed a degenerate density of states and that Cu(1-x)Pd(x)FeO2 was a semiconductor. A high ZT value of 0.055 was obtained for a Pd content of 0.03 at 950 K. The Pd2+ substitution for the Cu1+ sites influenced the thermoelectric and electronic properties of the delafossite Cu(1-x)Pd(x)FeO2 samples.

  11. Investigation of local structural environments and room-temperature ferromagnetism in (Fe,Cu)-codoped In2O3 diluted magnetic oxide films.

    Science.gov (United States)

    An, Yukai; Xing, Yaya; Pan, Fei; Wu, Zhonghua; Liu, Jiwen

    2016-05-11

    The local structural, optical, magnetic and transport properties of (In0.95-xFexCu0.05)2O3 (0.06 ≤ x ≤ 0.20) films deposited by RF-magnetron sputtering have been systemically studied by different experimental techniques. Detailed structural analyses using XRD, XPS, EXAFS and full multiple-scattering ab initio theoretical calculations of Fe K-edge XANES show that the (In0.95-xFexCu0.05)2O3 films have the same cubic bixbyite structure as pure In2O3. The doped Fe ions exist at both +2 and +3 oxidation states, substituting for the In(3+) sites in the In2O3 lattice and forming a FeIn + 2VO complex with the O vacancy in the first coordination shell of Fe. However, the co-doped Cu atoms are not incorporated into the In2O3 lattice and form the Cu metal clusters due to high ionization energy. UV-Vis measurements show that the optical band gap Eg decreases monotonically with the increase of Fe concentration, implying an increasing s-pd exchange interaction in the films. All the films display intrinsic room-temperature (RT) ferromagnetism and the saturated magnetization (Ms) increases monotonically with Fe doping. The temperature dependence of the resistivity data suggests the conduction mechanism of Mott variable-range hopping (VRH) at low temperature, confirming that the carriers are localized. It can be concluded that the observed RT ferromagnetism in the films originates from the overlapping of polarons mediated by oxygen vacancies based on the bound magnetic polaron (BMP) model. The variation of the localization effect of carriers with Fe doping can obviously adjust the magnetic exchange interaction in the (In0.95-xFexCu0.05)2O3 films.

  12. Ac conductivity and dielectric properties of CuFe{sub 1-x}Cr{sub x}O{sub 2} : Mg delafossite

    Energy Technology Data Exchange (ETDEWEB)

    Lalanne, M; Demont, P; Barnabe, A, E-mail: demont@cict.fr [Institut Carnot CIRIMAT, Universite de Toulouse UPS, 118 Route de Narbonne, 31062, Toulouse cedex 9 France (France)

    2011-05-11

    The electrical and dielectric properties of CuFe{sub 1-x}Cr{sub x}O{sub 2} (0 {<=} x {<=} 1) powders, doped with 3% of Mg and prepared by solid-state reaction, were studied by broadband dielectric spectroscopy in the temperature range from -100 to 150 {sup 0}C. The frequency-dependent electrical and dielectric data have been discussed in the framework of a power law conductivity and complex impedance and dielectric modulus. At room temperature, the ac conductivity behaviour is characteristic of the charge transport in CuFe{sub 1-x}Cr{sub x}O{sub 2} powders. The substitution of Fe{sup 3+} by Cr{sup 3+} results in an increase in dc conductivity and a decrease in the Cu{sup +}-Cu{sup +} distance. Dc conductivity, characteristic onset frequency and Havriliak-Negami characteristics relaxation times are thermally activated above -40 deg. C for x = 0.835. The associated activation energies obtained from dc and ac conductivity and from impedance and modulus losses are similar and show that CuFe{sub 1-x}Cr{sub x}O{sub 2} delafossite powders satisfy the BNN relation. Dc and ac conductivities have the same transport mechanism, namely thermally activated nearest neighbour hopping and tunnelling hopping above and below -40 {sup 0}C, respectively.

  13. Growth of Photosynthetic Biofilms and Fe, Pb, Cu, and Zn Speciation in Unsaturated Columns with Calcareous Mine Tailings from Arid Zones

    Directory of Open Access Journals (Sweden)

    J. V. García-Meza

    2011-01-01

    Full Text Available Mine tailing remediation aims to reduce the rate of sulfide mineral oxidation. Earlier studies showed that photosynthetic biofilms may act as a physical barrier against oxygen diffusion. Currently, a long-term assay (6 months is required to evaluate the solid phase redistribution of the Pb, Fe, Cu, and Zn originally present in historic and calcareous mine tailing samples (in our case from a semiarid region in North-Central Mexico. The presence of biofilms may provide chemical gradients and physical conditions that shift the proportion of Fe, Cu, and Zn originally associated with oxides to carbonates and organic matter/sulfide fractions.

  14. Structural, dielectric and magnetic properties of SnO{sub 2}-CuFe{sub 2}O{sub 4} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Kashif [Department of Physics, International Islamic University, Islamabad (Pakistan); Iqbal, Javed, E-mail: javed.saggu@qau.edu.pk [Laboratory of Nanoscience and Technology (LNT), Department of Physics, Qaid-i-Azam University, Islamabad (Pakistan); Jan, Tariq [Department of Physics, University of Lahore, Sargodha Campus, Sargodha (Pakistan); Wan, Dongyun [School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China); Ahmad, Naeem [Department of Physics, International Islamic University, Islamabad (Pakistan); Ahamd, Ishaq [Experimental Physics Labs, National Center for Physics, Islamabad (Pakistan); Ilyas, Syed Zafar [Department of Physics, Allama Iqbal Open University, Islamabad (Pakistan)

    2017-04-15

    The nanocomposites of (SnO{sub 2}){sub x}(CuFe{sub 2}O{sub 4}){sub (1−x)} (where x=0–100 wt%) have been successfully synthesized via two steps chemical method. XRD pattern has revealed the formation of inverse spinal phases with tetragonal crystal structure without any impurity phases for CuFe{sub 2}O{sub 4} sample. The thermodynamic solubility limit of SnO{sub 2} in CuFe{sub 2}O{sub 4} matrix has been found to be 30 wt% and above this percentage crystal phases related to SnO{sub 2} started to appear. The average particle size and shape of CuFe{sub 2}O{sub 4} nanoparticles have been strongly influenced by addition of SnO{sub 2} as depicted by TEM results. FTIR results have confirmed the existence of cation vibration bands at tetrahedral and octahedral sites along with Sn-O vibration band at higher concentrations, which also validates the formation of nanocomposites. Furthermore, the dielectric constant, tangent loss and conductivity of CuFe{sub 2}O{sub 4} nanoparticles have been found to increase up to 30 wt% addition of SnO{sub 2} and then decreases with further increase which is attributed to variations in resistivity and space charge carriers. Magnetic measurements have shown that saturation magnetization decreases from 35.68 emu/gm to 10.26 emu/gm with the addition of SnO{sub 2} content. - Highlights: • SnO{sub 2}-CuFe{sub 2}O{sub 4} nanocomposites with varying SnO{sub 2} concentrations were synthesized. • The thermodynamic solubility limit for SnO{sub 2} into CuFe{sub 2}O{sub 4} matrix by employing current method was found to be ≤30 wt%. • At higher concentrations, structural phases related to SnO{sub 2} started to appear. • FTIR results corroborated well with the XRD results. • It has been observed that the addition of SnO{sub 2} significantly influence the morphology, dielectric and magnetic properties of CuFe{sub 2}O{sub 4} nanoparticles.

  15. Speciation of Cr, Fe, Cu, Pb in the surface and under water sediment ...

    African Journals Online (AJOL)

    ... and carbonate bound fractions (2.01 µg/g and 4.02 µg/g) respectively. The result also indicated an increase in Cr concentrations at Fe-Mn oxide fraction of the bottom sediment (14.04 µg/g) compared to the surface sediment where Cr was not detected at the Fe-Mn oxide phase. Copper and Pb were generally not detected ...

  16. The effect of cobalt substitution in crystal structure and vibrational modes of CuFe{sub 2}O{sub 4} powders obtained by polymeric precursor method

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.D.P.; Silva, F.C. [Departamento de Química, CCET, Universidade Federal do Maranhão, 65085-580 São Luís, MA (Brazil); Sinfrônio, F.S.M. [Departamento de Engenharia Elétrica, CCET, Universidade Federal do Maranhão, 65085-580 São Luís, MA (Brazil); Paschoal, A.R. [Departamento de Física, Universidade Federal do Ceará, Campus do Pici, 60455-760 Fortaleza, CE (Brazil); Silva, E.N. [Departamento de Física, CCET, Universidade Federal do Maranhão, 65085-580 São Luís, MA (Brazil); Paschoal, C.W.A., E-mail: paschoal@ufma.br [Departamento de Física, CCET, Universidade Federal do Maranhão, 65085-580 São Luís, MA (Brazil); Department of Materials Science and Engineering, University of California Berkeley, 94720-1760 Berkeley, CA (United States); Department of Physics, University of California Berkeley, 94720-7300 Berkeley, CA (United States)

    2014-01-25

    Highlights: • We synthesized mixed spinels by polymeric precursor method. • We investigated the structural and vibrational properties of the mixed. • We investigated the synthesis condition effects in these properties. • We proposed a complete phonon description for CuFe{sub 2}O{sub 4} and CoFe{sub 2}O{sub 4} spinels. -- Abstract: In this work Co–Cu mixed spinel Co{sub 1−x}Cu{sub x}Fe{sub 2}O{sub 4} powders were obtained by polymeric precursors method at several annealing temperatures between 700 and 1200 °C. The samples were characterized by means of X-ray powder diffraction, confirming the ideal inverse spinel structure for CoFe{sub 2}O{sub 4} sample and the tetragonal distorted inverse spinel structure for CuFe{sub 2}O{sub 4} sample. Based on FWHM evaluation, we estimated that crystallite sizes varies between 27 and 37 nm for the non-substituted samples. The optical-active modes were determined by infrared and Raman spectroscopies. The phonon spectra showed a local tetragonal distortion for mixed samples.

  17. Hyperfine interaction and tuning of magnetic anisotropy of Cu doped CoFe{sub 2}O{sub 4} ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Batoo, Khalid Mujasam, E-mail: khalid.mujasam@gmail.com [King Abdullah Institute for Nanotechnology, King Saud University, P.O. Box-2455, Riyadh 11451 (Saudi Arabia); Salah, Dina [Department of Physics, Ain Shams University, Khalifa El-Maamon, Street, 11566 Cairo (Egypt); Kumar, Gagan; Kumar, Arun; Singh, Mahavir [Department of Physics, Himachal Pradesh University, Summer Hill, Shimla 171005 (India); Abd El-sadek, M. [Nanomaterials Lab, Physics Department, Faculty of Science, South Valley University, Qena 83523 (Egypt); Mir, Feroz Ahmad [University Science Instrumentation Centre, University of Kashmir, Srinagar 190006 (India); Imran, Ahamad [King Abdullah Institute for Nanotechnology, King Saud University, P.O. Box-2455, Riyadh 11451 (Saudi Arabia); Jameel, Daler Adil [School of Physics and Astronomy, Nottingham Nanotechnology and Nanoscience Center, University of Nottingham, NG7 2RD (United Kingdom)

    2016-08-01

    Ferrimagnetic oxides may contain single or multi domain particles which get converted into superparamagnetic state near a critical size. To explore the existence of these particles, we have made Mössbauer and magnetic studies of Cu{sup 2+} substitution effect in CoFe{sub 2−x}O{sub 4} Ferrites (0.0, 0.1, 0.2, 0.3, 0.4, and 0.5). All the samples have a cubic spinel structure with lattice parameters increasing linearly with increase in Cu content. The hysteresis loops yield a saturation magnetization, coercive field, and remanent magnetization that vary significantly with Cu content. The magnetic hysteresis curves shows a reduction in saturation magnetization and an increase in coercitivity with Cu{sup 2+} ion substitution. The anisotropy constant, K{sub 1,} is found strongly dependent on the composition of Cu{sup 2+} ions. The variation of saturation magnetization with increasing Cu{sup 2+} ion content has been explained in the light of Neel's molecular field theory. Mössbauer spectra at room temperature shows two ferrimagnetically relaxed Zeeman sextets. The dependence of Mössbauer parameters such as isomer shift, quadrupole splitting, line width and hyperfine magnetic field on Cu{sup 2+} ion concentration have been discussed. - Highlights: • Synthesis of the nanoparticles of Cu doped CoFe{sub 2}O{sub 4} ferrite nanoparticles. • The samples were characterized for the structural, morphological and magnetic studies using XRD, TEM, VSM and Mossbauer spectroscopy. • It has been found that the all the magnetic and Mossbauer parameters are diluted with the addition of Cu content in the CoFe{sub 2}O{sub 4} matrix. • The Mossbauer and magnetic properties were studied in the light of size of nanoparticles and also with respect to the doping composition.

  18. Creep and creep fracture of high corrosion resistant zirconium alloy Zr-Cu-Fe-Mo-V. [(Zr-0. 4% Cu-0. 4% Fe-0. 55% Mo-0. 20% v)

    Energy Technology Data Exchange (ETDEWEB)

    Kucharova, K.; Pahutova, M.; Polesna, M.; Cadek, J. (Ceskoslovenska Akademie Ved, Brno. Ustav Fyzikalni Metalurgie); Kloc, K.; Hamouz, V. (Vyvojovy Zavod Uranoveho Prumyslu, Zbraslav nad Vltavou (Czechoslovakia). Ustav Jadernych Paliv)

    1981-01-01

    The experimental alloy consisted of Zr-0.40% Cu-0.40% Fe-0.55% Mo-0.20% V. Two types of specimens were prepared, namely a martensitic highly corrosion resistant alloy (VKO-M) and a recrystallization annealed highly corrosion resistant alloy (VKO-R). The effects on creep characteristics were studied of hardening, tempering and recrystallization annealing. Stresses were estimated at which an elongation of 1% took place in 10/sup 5/ h. For alloy VKO-M, stress values of 75, 50 and 30 MPa corresponded to 673, 723 and 773 K, respectively. For alloy VKO-R, a stress value of 7 MPa was measured for a temperature of 773 K. The results were compared with a previous study of the creep of martensitic alloy Zr-4.5% Sn-1% Mo.

  19. Effects of the Fe/Mn weight ratio and cooling rate on the area fractions of α-AlFeSi and β-AlFeSi phases in Al-7.5Si-3.75Cu-0.5Mg-0.55Fe-xMn aluminum alloy

    OpenAIRE

    Hernández-Rodríguez, A.; Castro-Román, M. de J.; M. Herrera-Trejo; S. Belmares-Perales; P. Orozco-González

    2014-01-01

    The effects of the Fe/Mn weight ratio (1,42 or 3,05) and cooling rate (0,1, 0,2, 0,5, or 0,6 °C/s) on the area fraction of α-AlFeSi and β-AlFeSi intermetallic compounds in Al-7.5Si-3.75Cu-0.5Mg-0.55Fe-xMn aluminum alloy were studied. It was found that the difference between the formation temperature of the β-AlFeSi phase and the formation temperature of the eutectic Al-Si may determine the possibilities of β-AlFeSi elimination/reduction by increasing the cooling rate.

  20. Effects of the Fe/Mn weight ratio and cooling rate on the area fractions of α-AlFeSi and β-AlFeSi phases in Al-7.5Si-3.75Cu-0.5Mg-0.55Fe-xMn aluminum alloy

    Directory of Open Access Journals (Sweden)

    A. Hernández-Rodríguez

    2014-07-01

    Full Text Available The effects of the Fe/Mn weight ratio (1,42 or 3,05 and cooling rate (0,1, 0,2, 0,5, or 0,6 °C/s on the area fraction of α-AlFeSi and β-AlFeSi intermetallic compounds in Al-7.5Si-3.75Cu-0.5Mg-0.55Fe-xMn aluminum alloy were studied. It was found that the difference between the formation temperature of the β-AlFeSi phase and the formation temperature of the eutectic Al-Si may determine the possibilities of β-AlFeSi elimination/reduction by increasing the cooling rate.

  1. Effect of Copper on Passivity and Corrosion Behavior of Fe-xC-5Cu ...

    African Journals Online (AJOL)

    The coupled effect copper/microstructure is discussed. Alloying Cu showed a beneficial effect on hypoeutectoid steel and harmful effect on hypereutectoid steel. The improved corrosion resistance is related to cementite morphology and by a copper dissolution/re-deposition process. Keywords: Corrosion; Copper; cementite; ...

  2. Heterogeneous Degradation of Organic Pollutants by Persulfate Activated by CuO-Fe3O4: Mechanism, Stability, and Effects of pH and Bicarbonate Ions.

    Science.gov (United States)

    Lei, Yang; Chen, Chuh-Shun; Tu, Yao-Jen; Huang, Yao-Hui; Zhang, Hui

    2015-06-02

    Magnetic CuO-Fe3O4 composite was fabricated by a simple hydrothermal method and characterized as a heterogeneous catalyst for phenol degradation. The effects of pH and bicarbonate ions on catalytic activity were extensively evaluated in view of the practical applications. The results indicated that an increase of solution pH and the presence of bicarbonate ions were beneficial for the removal of phenol in the CuO-Fe3O4 coupled with persulfate (PS) process. Almost 100% mineralization of 0.1 mM phenol can be achieved in 120 min by using 0.3 g/L CuO-Fe3O4 and 5.0 mM PS at pH 11.0 or in the presence of 3.0 mM bicarbonate. The positive effect of bicarbonate ion is probably due to the suppression of copper leaching as well as the formation of Cu(III). The reuse of catalyst at pH0 11.0 and 5.6 showed that the catalyst remains a high level of stability at alkaline condition (e.g., pH0 11.0). On the basis of the characterization of catalyst, the results of metal leaching and EPR studies, it is suggested that phenol is mainly destroyed by the surface-adsorbed radicals and Cu(III) resulting from the reaction between PS and Cu(II) on the catalyst. Taking into account the widespread presence of bicarbonate ions in waste streams, the CuO-Fe3O4/PS system may provide some new insights for contaminant removal from wastewater.

  3. Electronic and optical properties of Cu2XSnS4 (X = Be, Mg, Ca, Mn, Fe, and Ni) and the impact of native defect pairs

    Science.gov (United States)

    Chen, Rongzhen; Persson, Clas

    2017-05-01

    Reducing or controlling cation disorder in Cu2ZnSnS4 is a major challenge, mainly due to low formation energies of the anti-site pair ( CuZn - + ZnCu +) and the compensated Cu vacancy ( VCu - + ZnCu +). We study the electronic and optical properties of Cu2XSnS4 (CXTS, with X = Be, Mg, Ca, Mn, Fe, and Ni) and the impact of defect pairs, by employing the first-principles method within the density functional theory. The calculations indicate that these compounds can be grown in either the kesterite or stannite tetragonal phase, except Cu2CaSnS4 which seems to be unstable also in its trigonal phase. In the tetragonal phase, all six compounds have rather similar electronic band structures, suitable band-gap energies Eg for photovoltaic applications, as well as good absorption coefficients α(ω). However, the formation of the defect pairs ( C u X + X Cu) and ( V Cu + X Cu) is an issue for these compounds, especially considering the anti-site pair which has formation energy in the order of ˜0.3 eV. The ( C u X + X Cu) pair narrows the energy gap by typically ΔEg ≈ 0.1-0.3 eV, but for Cu2NiSnS4, the complex yields localized in-gap states. Due to the low formation energy of ( C u X + X Cu), we conclude that it is difficult to avoid disordering from the high concentration of anti-site pairs. The defect concentration in Cu2BeSnS4 is however expected to be significantly lower (as much as ˜104 times at typical device operating temperature) compared to the other compounds, which is partly explained by larger relaxation effects in Cu2BeSnS4 as the two anti-site atoms have different sizes. The disadvantage is that the stronger relaxation has a stronger impact on the band-gap narrowing. Therefore, instead of trying to reduce the anti-site pairs, we suggest that one shall try to compensate ( C u X + X Cu) with ( V Cu + X Cu) or other defects in order to stabilize the gap energy.

  4. Effects of Pd substitution on the thermoelectric and electronic properties of delafossite Cu{sub 1−x}Pd{sub x}FeO{sub 2} (x=0.01, 0.03 and 0.05)

    Energy Technology Data Exchange (ETDEWEB)

    Ruttanapun, Chesta, E-mail: chesta.ruttanapun@gmail.com

    2014-07-01

    Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} (x=0.01, 0.03 and 005) delafossite was prepared by solid state reactions and was calcined/sintered at 1050 °C. The effect of Pd{sup 2+} substitution for the Cu{sup 1+} sites on the thermoelectric and electronic properties of Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} were investigated. The crystal structure, oxygen decomposition, thermoelectric and electronic properties were characterized by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS), Seebeck coefficient, electrical conductivity and thermal conductivity measurements. The characterization showed that Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} formed a hexagonal delafossite structure with R3−m symmetry. The existence of Pd{sup 2+}, Cu{sup 1+}, Cu{sup 2+}, Fe{sup 3+}, Fe{sup 4+} and O was revealed from the XPS results. Confirmation of Pd{sup 2+} substitution for the Cu{sup 1+} sites occurred by increasing the c-axis in the lattice parameter with a Pd content. The O content intercalated at the center of the triangular Cu acted as a support to produce Cu{sup 2+} ions and was reduced with an increasing Pd content. The mixed valencies of Cu{sup 1+}/Cu{sup 2+} and Cu{sup 1+}/Pd{sup 2+} in the Cu layer changed the electrical conductivity and the Fe{sup 3+}/Fe{sup 4+} mixed valencies in the FeO{sub 6} layer caused the Seebeck coefficient to increase. Both the electrical conductivity and Seebeck coefficient for Pd contents of x=0.01 and 0.03 were higher than that of non-doped CuFeO{sub 2}. The low thermal conductivity of Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} resulted from the substitution of Pd, which has a large atomic mass, into structure. The Jonker plot indicated that the electronic properties displayed a degenerate density of states and that Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} was a semiconductor. A high ZT value of 0.055 was obtained for a Pd content of 0.03 at 950 K. The Pd{sup 2+} substitution for the Cu{sup 1+} sites influenced the thermoelectric

  5. Determination of Cr, Cu, Fe, Ni, Pb and Zn by ICP-OES in mushroom samples from Sakarya, Turkey

    Directory of Open Access Journals (Sweden)

    Esra Altıntığ

    2017-06-01

    Full Text Available Russula cyanoxantha, Russula delica, Lactarius salmonicolor, Lactarius deliciosus, Pleurotus eryngii, Pleurotus ostreatus, Agaricus bisporus, Suillus luteus, Pleurotus spp and Boletus edulis were collected from Sakarya-Turkey respectively. Also canned food in the form of the Pleurotus eryngii, Pleurotus ostreatus, and Lactarius salmonicolor mushrooms were used for the examination. Trace metal concentrations found in these mushrooms were determined inductively using coupled plasma optic emission spectrometry microwave processes. The results were obtained for (Cr 0.3-26.65, (Cu 17.38-132.75, (Fe 26.3-225.40, (Ni 2.57-39.28, (Pb 11.52-185.20, and (Zn 22.86-126.84 mg/kg. The accuracy of the method was checked by the standard reference material; tea leaves (INCY-TL-1 and tomato leaves (1573a.

  6. Ab initio study of the diatomic fluorides FeF, CoF, NiF, and CuF.

    Science.gov (United States)

    Koukounas, Constantine; Mavridis, Aristides

    2008-11-06

    The late-3d transition-metal diatomic fluorides MF = FeF, CoF, NiF, and CuF have been studied using variational multireference (MRCI) and coupled-cluster [RCCSD(T)] methods, combined with large to very large basis sets. We examined a total of 35 (2S+1)|Lambda| states, constructing as well 29 full potential energy curves through the MRCI method. All examined states are ionic, diabatically correlating to M(+)+F(-)((1)S). Notwithstanding the "eccentric" character of the 3d transition metals and the difficulties to accurately be described with all-electron ab initio methods, our results are, in general, in very good agreement with available experimental numbers.

  7. Interfacial effects revealed by ultrafast relaxation dynamics in BiFeO 3 / YBa 2 Cu 3 O 7 bilayers

    KAUST Repository

    Springer, D.

    2016-02-12

    The temperature dependence of the relaxation dynamics in the bilayer thin film heterostructure composed of multiferroic BiFeO3 (BFO) and superconducting YBa2Cu3O7 (YBCO) grown on a (001) SrTiO3 substrate is studied by a time-resolved pump-probe technique, and compared with that of pure YBCO thin film grown under the same growth conditions. The superconductivity of YBCO is found to be retained in the heterostructure. We observe a speeding up of the YBCO recombination dynamics in the superconducting state of the heterostructure, and attribute it to the presence of weak ferromagnetism at the BFO/YBCO interface as observed in magnetization data. An extension of the Rothwarf-Taylor model is used to fit the ultrafast dynamics of BFO/YBCO, that models an increased quasiparticle occupation of the ferromagnetic interfacial layer in the superconducting state of YBCO.

  8. Intermetallic M--Sn.sub.5 (M=Fe, Cu, Co, Ni) compound and a method of synthesis thereof

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiao-Liang; Han, Weiqiang

    2017-09-05

    Novel intermetallic materials are provided that are composed of tin and one or more additional metal(s) having a formula M.sub.(1-x)-Sn.sub.5, where -0.1.ltoreq.x.ltoreq.0.5, with 0.01.ltoreq.x.ltoreq.0.4 being more preferred and the second metallic element (M) is selected from iron (Fe), copper (Cu), cobalt (Co), nickel (Ni), and a combination of two or more of those metals. Due to low concentration of the second metallic element, the intermetallic compound affords an enhanced capacity applicable for electrochemical cells and may serve as an intermediate phase between Sn and MSn.sub.2. A method of synthesizing these intermetallic materials is also disclosed.

  9. Precipitation Behavior and Magnetic Properties of Cu-Fe-Co Alloys Containing Nanogranular Ferromagnetic-Element Particles

    Directory of Open Access Journals (Sweden)

    N. Wada

    2015-01-01

    Full Text Available This work investigates the evolution of microstructures and magnetic properties during isothermal annealing of Cu-Fe-Co alloys, using electron microscopy and superconducting quantum interference device (SQUID magnetometry. Small coherent granular precipitates composed of iron and cobalt formed in the copper matrix in the early stage of precipitation. As annealing proceeded, the precipitates lost coherency to the matrix after reaching a size of 15–20 nm and twin-like structures were consecutively introduced in the particles. The SQUID measurements revealed that the magnetic properties of the specimens correlated with the microstructural evolution. The coercive force initially increased with annealing time but decreased after reaching a peak. Lorentz Microscopy suggested that the initial large increase of magnetization was invoked by a structural transition from fcc to B2 in the precipitates.

  10. Optical properties of reduced graphene oxide and CuFe2O4 composites in the IR region

    Science.gov (United States)

    Ma, De-yue; Li, Xiao-xia; Guo, Yu-xiang; Zeng, Yu-run

    2018-01-01

    The complex refractive index of reduced graphene oxide and CuFe2O4 composites prepared by hydrothermal method was calculated using infrared Micro-reflective spectra and K-K relation, and the calculation errors were analyzed according to its IR transmission and spectral reflectivity calculated by Fresnel formula. And then normal emissivity of the composite in IR atmospheric window was calculated by means of Fresnel formula and modified refraction angle formula. The calculation accuracy was verified by comparing measured normal total emissivity with the calculated one. The results show that complex refractive index and normal emissivity calculated by the formulas have a high accuracy. It has been found that the composite has a good absorption and radiation characteristics in IR atmospheric window and a strong scattering ability in middle IR region by analyzing its extinction, absorption and radiation properties in IR region. Therefore, it may be used as IR absorption, extinction and radiation materials in some special fields.

  11. Interactions of anti-Parkinson drug benserazide with Zn(II), Cu(II), Fe(II) ions.

    Science.gov (United States)

    Szyrwiel, Lukasz; Pap, József S; Malinka, Wieslaw; Szewczuk, Zbigniew; Kotynia, Aleksandra; Brasun, Justyna

    2013-03-25

    One of the treatments of Parkinson disease is based on increasing the brain dopamine level by L-DOPA (LD) applications. To prevent the peripheral degradation of levodopa, another drug, benserazide is applied. On the other hand, during this neurodegenerative disease changes in the homeostasis of metals are observed and the increasing brain zinc levels are postulated to have therapeutic effects. Here we present studies on interactions of Zn(II), Cu(II), Fe(II) ions with benserazide and with benserazide/levodopa in ternary system. By applying mass spectrometry and UV-vis methods we describe the interactions between selected metal ions and the drug additives in the investigated systems. The results show forming of equimolar complexes in the binary and ternary systems. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Plasticity performance of Al 0.5 CoCrCuFeNi high-entropy alloys under nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Li-ping; Chen, Shu-ying; Ren, Jing-li; Ren, Yang; Yang, Fu-qian; Dahmen, Karin A.; Liaw, Peter K.

    2017-04-01

    The statistical and dynamic behaviors of the displacement-load curves of a high-entropy alloy, Al0.5 CoCrCuFeNi, were analyzed for the nanoindentation performed at two temperatures. Critical behavior of serrations at room temperature and chaotic flows at 200 °C were detected. These results are attributed to the interaction among a large number of slip bands. For the nanoindentation at room temperature, recurrent partial events between slip bands introduce a hierarchy of length scales, leading to a critical state. For the nanoindentation at 200 °C, there is no spatial interference between two slip bands, which is corresponding to the evolution of separated trajectory of chaotic behavior

  13. Thermal, magnetic, and structural properties of soft magnetic FeCrNbCuSiB alloy ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Rosales-Rivera, A. [Laboratorio de Magnetismo y Materiales Avanzados, Universidad Nacional de Colombia, A.A. 127, Manizales (Colombia)]. E-mail: arosalesr@unal.edu.co; Valencia, V.H. [Laboratorio de Magnetismo y Materiales Avanzados, Universidad Nacional de Colombia, A.A. 127, Manizales (Colombia); Quintero, D.L. [Laboratorio de Magnetismo y Materiales Avanzados, Universidad Nacional de Colombia, A.A. 127, Manizales (Colombia); Pineda-Gomez, P. [Laboratorio de Magnetismo y Materiales Avanzados, Universidad Nacional de Colombia, A.A. 127, Manizales (Colombia); Gomez, M. [Laboratorio de Magnetismo y Materiales Avanzados, Universidad Nacional de Colombia, A.A. 127, Manizales (Colombia)

    2006-10-01

    The thermal, magnetic and structural properties of amorphous magnetic Fe{sub 73.5-x}Cr{sub x}Nb{sub 3}Cu{sub 1}Si{sub 13.5}B{sub 9} alloy ribbons, with x=0, 2, 4, 6, 8, and 10, were studied by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), magneto-impedance measurements and X-ray diffraction (XRD). The ribbons exhibit ultrasoft magnetic behavior, especially giant magneto-impedance effect, GMI. A three-peak behavior was observed in GMI curves. Particular attention has been given to observation of crystallization kinetics via DSC and TGA. The primary crystallization T{sub pcr}, and Curie T{sub c}, temperatures were determined from DSC and TGA data, respectively. The effect of partial substitution of iron by Cr on the thermal and magnetic properties is discussed.

  14. Determination of the impurities Al, Mn, Fe, Ni, Cu and Zn in nuclear grade uranium by ICP-OES

    Energy Technology Data Exchange (ETDEWEB)

    Kakazu, Mauricio H.; Cotrim, Marycel E.B.; Silva, Douglas B. da; Pires, Maria Aparecida F., E-mail: mhkakazu@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Uranium compounds are specially produced for use in nuclear reactors and must meet strict physical and chemicals specifications. The current study discusses the separation of Al, Mn, Fe, Ni, Cu and Zn from uranium compounds and their quantitative determination using inductively coupled plasma optical emission spectrometry. To avoid interference effect caused by uranium in the spectroscopic emission lines of elements of interest, the chromatographic behavior of TBP impregnated macroporous Amberlite XAD-4 column was investigated. The break through curves of uranium obtained showed maximum retention of up to 11 grams of uranium and the elution curves for the elements showed reproducible recovery rate of 90% on 50 mL elution. Synthetic samples of nuclear grade uranium prepared with the addition of 250 {mu}g/g of U of the above individual elements were used to verify the performance of the method. The method showed a recovery rate of 80 to 90% for the elements under study. (author)

  15. Quantitative trait loci controlling Cu, Ca, Zn, Mn and Fe content in ...

    Indian Academy of Sciences (India)

    The human body requires more than 22 mineral elements that can be supplied by an appropriate diet (Philip and Mar- tin 2005). However, the diets of the populations subsist- ing largely on cereals, or inhabiting regions where soil min- eral imbalances occur, often lack Fe, Zn, Ca, Mg and Mn. These minerals are known to ...

  16. The Status of Zn, Cu, Mil, and Fe in the Soils and Tea Leaves of ...

    African Journals Online (AJOL)

    ... a reflection of their high contents in the soils and foliar application at a rate of 2 kgha-1, respectively. Although Fe was observed to be sufficient in soils, it was poorly reflected in tea leaves of which 65.22% of samples were deficient. This phenomena is explained by high levels of Zn in tea leaves which reduces the uptake ...

  17. Determination of Mn, Fe, Ni, Cu, Zn and Pb contents in samples of apple trees by radionuclide X-ray fluorescence analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bumbalova, A.; Havranek, E.; Harangozo, M. (Komenskeho Univ., Bratislava (Czechoslovakia). Farmaceuticka Fakulta)

    1982-12-01

    The applicability of the radionuclide X-ray fluorescence analysis (RXFA) for qualitative and quantitative evaluation of environmental plant samples is discussed and examples of determination of Mn, Fe, Ni, Cu, Zn, Pb in samples of apple trees are given. The instrumentation, the standard and sample preparation are also presented.

  18. Chalcogenide Quaternary Cu2FeSnS4 Nanocrystals for Solar Cells: Explosive Character of Mechanochemical Synthesis and Environmental Challenge

    Directory of Open Access Journals (Sweden)

    Peter Baláž

    2017-12-01

    Full Text Available In this study we demonstrate the synthesis of quaternary semiconductor nanocrystals of stannite Cu2FeSnS4/rhodostannite Cu2FeSn3S8 (CFTS via mechanochemical route using Cu, Fe, Sn and S elements as precursors in one-pot experiments. Methods of X-ray diffraction (XRD, nitrogen adsorption, high-resolution transmission electron microscopy (HRTEM, scanning transmission electron microscopy (STEM, energy-dispersive X-ray spectroscopy (EDX and X-ray photoelectron spectroscopy (XPS were applied to characterize properties of the unique nanostructures. Mechanochemical route of synthesis induced new phenomena like explosive character of reaction, where three stages could be identified and the formation of nanostructures 5–10 nm in size. By using XPS method, Cu(I, Fe(II, Sn(IV and S(-II species were identified on the surface of CFTS. The value of optical band gap 1.27 eV is optimal for semiconductors applicable as absorbers in solar cells. The significant photocatalytic activity of the CFTS nanocrystals was also evidenced. The obtained results confirm the excellent properties of the quaternary semiconductor nanocrystals synthesized from earth-abundant elements.

  19. [Measurement and comparison of Zn, Fe, Cu, Mn, Cr, Pb and Cd in rabbit liver of high-adipose group and normal group].

    Science.gov (United States)

    Wu, Yun-Kai; Cao, Hong; Mao, Chang-Jie; Gu, Zhi-Hong; Wang, Yuan

    2012-11-01

    The objective of the present paper is to explore the experimental changes in the content of Zn, Fe, Cu, Mn, Cr, Pb and Cd in white rabbit liver with atherosclerosis disease. The method is to reproduce white rabbit liver with atherosclerosis disease by a high-fat diet, and then measure the Zn, Fe, Cu, Mn, Cr, Pb and Cd content with atomic absorption spectrometry. Results show that the Zn, Fe, Cu, Mn, Cr, Pb and Cd contents in the fodders of the normal group are 137.6, 362.3, 14.39, 9.599 mg x kg(-1) and 159.3, 355.0, 290.0 microg x kg(-1), and 86.09, 277.1, 11.07, 5.366 mg x kg(-1) and 115.2, 286.0, 210.5 microg x kg(-1), in high-adipose group. It was concluded that Zn, Fe, Cu, Mn, Cr, Pb and Cd contents in white rabbit liver decline, which may have something to do with the intake of foods and the abnormalities of lipoprotein metabolism.

  20. Use of anomalous scattering for synchrotron X-ray reflectivity studies of Fe-Cr and Co-Cu double layers

    CERN Document Server

    Prokert, F; Gorbunov, A

    2003-01-01

    Double layers of Fe-Cr and Co-Cu, respectively, were prepared on oxidized Si substrates by pulsed laser deposition (PLD). The interfacial roughness structure was studied by synchrotron X-ray reflectivity measurements at the absorption K-edges using the contrast enhancement due to resonant scattering. The results are determined from simulations of the measured specular and diffuse scans. Whereas in Fe-Cr double layers the sigma sub r sub m sub s -interface width for Fe deposition on Cr (sigma sub C sub r =0.70+-0.1 nm) is not very different from that of Cr deposition on Fe (sigma sub F sub e =0.85+-0.1 nm), in Co-Cu double layers, in contrast, for Cu deposition on Co, the width (sigma sub C sub o =0.65+-0.1 nm) is much smaller than for Co deposition on Cu (sigma sub C sub u =1.5+-0.15 nm). On the basis of the fractal model to describe the interface roughness morphology, from the off-specular scans the lateral roughness correlation length, xi and the roughness exponent, h, were determined. For both types of dou...

  1. Effects of Cu or Ag additions on the kinetics of MgB2 phase formation in Fe-sheated wires

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Abrahamsen, Asger Bech; Bednarcik, J.

    2008-01-01

    MgB2/Fe wires have been produced by the powder-in-tube technique following the in situ route. The influence of low amounts of Cu or Ag additions into the precursor powder mixture on the kinetics of MgB2 formation was studied in situ by means of synchrotron x-ray diffraction during heat-treatments......MgB2/Fe wires have been produced by the powder-in-tube technique following the in situ route. The influence of low amounts of Cu or Ag additions into the precursor powder mixture on the kinetics of MgB2 formation was studied in situ by means of synchrotron x-ray diffraction during heat......-treatments at 504 and 547 degrees C. Both Cu and Ag additions result in a significant increase of the MgB2 formation rate. A thin, discontinuous Fe2B layer was formed at the interface between the MgB2 core and the Fe sheath. At the end of the heat-treatment, Cu and Ag were found in submicrometer-sized particles...

  2. Feasibility of dispersive liquid-liquid microextraction for extraction and preconcentration of Cu and Fe in red and white wine and determination by flame atomic absorption spectrometry

    Science.gov (United States)

    Seeger, Tassia S.; Rosa, Francisco C.; Bizzi, Cezar A.; Dressler, Valderi L.; Flores, Erico M. M.; Duarte, Fabio A.

    2015-03-01

    A method for extraction and preconcentration of Cu and Fe in red and white wines using dispersive liquid-liquid microextraction (DLLME) and determination by flame atomic absorption spectrometry (F AAS) was developed. Extraction was performed using sodium diethyldithiocarbamate as chelating agent and a mixture of 40 μL of 1,2-dichlorobenzene (extraction solvent) and 900 μL of methanol (dispersive solvent). Some parameters that influencing the extraction efficiency such as pH (2 to 5), concentration of chelating agent (0 to 2%), effect of salt addition (0 to 10%), number of washing steps (1 to 4) and centrifugation time (0 to 15 min) were studied. Accuracy was evaluated after microwave-assisted digestion in closed vessels and analytes were determined by inductively coupled plasma optical emission spectrometry. Agreement with the proposed method ranged from 91 to 110 and from 89 to 113% for Cu and Fe, respectively. Calibration of F AAS instrument was performed using analyte addition method and limits of detection were 6.3 and 2.4 μg L- 1 for Cu and Fe, respectively. The proposed method was applied for the determination of Cu and Fe in five samples of red wine and three samples of white wine, with concentration ranging from 21 to 178 μg L- 1 and from 1.38 to 3.74 mg L- 1, respectively.

  3. On the concentration and separation of the trace-elements Fe, Cu, Zn, Mn, Pb, Mo and Co : II. Solvent extraction

    NARCIS (Netherlands)

    Erkelens, P.C. van

    Extractions with acetylacetone and diethyldithiocarbamate are described. Through the successive application of these reagents the constituents of biological ashes are concentrated and separated into the groups: (I) MoO4−2, (2) Fe+3, Cu+2, (3) Mn+2, (4) Zn+2, (5) Pb+2, (6) Co+3 and (7) Na+, K+, Ca+2,

  4. Seasonal variation of major elements (Ca, Mg) and trace metals (Fe, Cu, Zn, Mn) and cultured mussel Perna viridis L. and seawater in the Dona Paula Bay, Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Rivonker, C; Parulekar, A.H.

    The major elements and trace metals were analysed from nussel tissue and the seawater taken from three depths (0, 5 and 9 meters) from the culture site. Range of variation in Ca, Mg, Fe, Cu, Zn and Mn were 226-399; 708-1329; 0.005-0.084; BDL-0...

  5. Structural, optical and morphological characterization of Cu-doped α-Fe2O3 nanoparticles synthesized through co-precipitation technique

    Science.gov (United States)

    Lassoued, Abdelmajid; Lassoued, Mohamed Saber; Dkhil, Brahim; Gadri, Abdellatif; Ammar, Salah

    2017-11-01

    Pure and copper (Cu concentration varying from 2 to 8%) doped hematite (α-Fe2O3) nanocrystals were synthesized through co-precipitation method using simple equipment. X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FT-IR), Raman spectroscopy, Differential Thermal Analysis (DTA), Thermo Gravimetric Analysis (TGA) and Ultraviolet-Visible (UV-Vis) techniques were used to characterize the synthesized samples. XRD measurements confirm that all the prepared nanocrystals consist only in nanocrystalline hematite phase. These results along with TEM and SEM show that the size of the nanoparticles decreases with Cu-doping down to 21 nm. FT-IR confirm the phase purity of the nanoparticles synthesized. The Raman spectroscopy was used not only to prove that we synthesized pure and Cu-doped hematite but also to identify their phonon modes. The TGA showed three mass losses, whereas DTA resulted in three endothermic peaks. The UV-Vis absorption measurements confirm that the decrease of particle size is accompanied by a decrease in the band gap value from 2.12 eV for pure α-Fe2O3 down to 1.91 eV for 8% Cu-doped α-Fe2O3. 8% Cu-doped hematite had the smallest size, the best crystallinity and the lowest band gap.

  6. The mechanism of degradation of bisphenol A using the magnetically separable CuFe{sub 2}O{sub 4}/peroxymonosulfate heterogeneous oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yin; Ai, Jia [Department of Environmental Engineering, Wuhan University, Wuhan 430079 (China); Shenzhen Research Institute of Wuhan University, Shenzhen 518057 (China); Zhang, Hui, E-mail: eeng@whu.edu.cn [Department of Environmental Engineering, Wuhan University, Wuhan 430079 (China); Shenzhen Research Institute of Wuhan University, Shenzhen 518057 (China)

    2016-05-15

    Highlights: • Copper ferrite (CuFe{sub 2}O{sub 4}) was fabricated and utilized in heterogeneous PMS process. • The influence of reaction parameters for the mineralization of BPA were evaluated. • Possible reaction mechanism and the stability of CuFe{sub 2}O{sub 4} were investigated. • Surface bound radicals (mainly ·OH) may be responsible for the BPA degradation. - Abstract: The removal of bisphenol A (BPA) in aqueous solution by an oxidation process involving peroxymonosulfate (PMS) activated by CuFe{sub 2}O{sub 4} magnetic nanoparticles (MNPs) is reported herein. The effects of PMS concentration, CuFe{sub 2}O{sub 4} dosage, initial pH, initial BPA concentration, catalyst addition mode, and anions (Cl{sup −}, F{sup −}, ClO{sub 4}{sup −} and H{sub 2}PO{sub 4}{sup −}) on BPA degradation were investigated. Results indicate that nearly complete removal of BPA (50 mg/L) within 60 min and 84.0% TOC removal in 120 min could be achieved at neutral pH by using 0.6 g/L CuFe{sub 2}O{sub 4} MNPs and 0.3 g/L PMS. The generation of reactive radicals (mainly hydroxyl radicals) was confirmed using electron paramagnetic resonance (EPR). Possible mechanisms on the radical generation from CuFe{sub 2}O{sub 4}/PMS system are proposed based on the results of radical identification tests and XPS analysis. The lack of inhibition of the reaction by free radical scavengers such as methanol and tert-butyl alcohol suggests that these species may not be generated in the bulk solution, and methylene blue probe experiments confirm that this process does not involve free radical generation. Surface-bound, rather than free radicals generated by a surface catalyzed-redox cycle involving both Fe(III) and Cu(II), are postulated to be responsible for the mineralization of bisphenol A.

  7. Microstrucural characterization of gas atomized Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} and Fe{sub 97}Si{sub 3} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Escorial, A., E-mail: age@cenim.csic.es [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Lieblich, M. [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Lopez, M.; Marin, P. [Instituto de Magnetismo Aplicado, P.O. Box 155, 28230 Madrid (Spain)

    2011-06-15

    Research highlights: > Two FeSi-base alloys as precursors for small dimension soft magnets. > Small particles rapidly solidified by gas atomisation. > Increase effective magnetic anisotropy constant by alloying segregation. > Magnetic hardenning due to volume decrease. - Abstract: Powder particles of Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} and Fe{sub 97}Si{sub 3} soft magnetic alloys have been prepared by gas atomization. The gas atomized powder was microstructurally characterized and the dependence of coercivity with the composition and powder particle size investigated. As-atomized powder particles of both compositions were constituted by a bcc {alpha}-Fe (Si) solid solution. The Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} powder particles presented a grain microstructure with dendrite structure, which dendrite arms were enriched in Nb. The coercivity increased as the particle size decreased, with a minimum coercivity, of 5 Oe, measured in the Fe{sub 97}Si{sub 3} alloy in the range of 50-100 {mu}m powder particle size. The coercive fields were quite higher in the Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} than in the Fe{sub 97}Si{sub 3} powder, due to the Nb addition, which produced a phase segregation that leads to a noticeable magnetic hardening.

  8. In vitro oral bioaccessibility and total content of Cu, Fe, Mn and Zn from transgenic (through cp4 EPSPS gene) and nontransgenic precursor/successor soybean seeds.

    Science.gov (United States)

    Herrera-Agudelo, Mónica A; Miró, Manuel; Arruda, Marco A Z

    2017-06-15

    In this paper, Cu, Fe, Mn and Zn contents in transgenic (T - MSOY7122RR) and non-transgenic (NT - MSOY8200) soybean seeds, sown at summer and winter cultivation periods are investigated using four microwave decomposition methods. Student's t tests demonstrate significant differences (p=0.05; n=4), for Cu, Mn and Zn (namely, 8, 9 and 26% higher concentrations in T compared to NT seeds, respectively). Through principal component analysis, precursor and successor soybean seeds are identified. Cu is demonstrated to play an important role in the differentiation of the cultivars, whereas Fe and Zn are of particular relevance in the classification of seeds cultivated in winter against those in summer. Using in vitro extraction based on the Unified Bioaccessibility Method, the bioaccessibility of the above nutrients is proven to differ in both the gastric and gastrointestinal phases on the basis of the transgenesis and the cultivation periods. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Influence of Cr Doping on the Critical Behavior of Amorphous Alloy Ribbons Fe78–xCrxSi4Nb5B12Cu1

    DEFF Research Database (Denmark)

    Phan, The-Long; Thanh, P. Q.; Chau, N.

    2014-01-01

    Though many previous works focused on studying Cr-doped Fe–Si–Nb–B–Cu amorphous alloys, magnetic-interaction mechanismsin these materials have not been carefully investigated yet. Dealing with these issues, we have prepared the amorphous alloy ribbonsFe78−xCrx Si4Nb5B12Cu1 with x = 1, 3, and 6......, and then studied their magnetic and critical properties. Magnetization versustemperature and magnetic-field measurements, MHT, performed on a vibrating sample magnetometer reveal that the Cr-contentincrease in Fe78−xCrxSi4Nb5B12Cu1 reduces the TC from 430 K for x = 1 to about 322 K (for x = 6). This indicates...

  10. Electrical and optical properties of p-type CuFe1-xSnxO2 (x = 0.03, 0.05) delafossite-oxide

    Science.gov (United States)

    Ruttanapun, Chesta; Boonchom, Banjong; Thongkam, Montree; Kongtaweelert, Samart; Thanachayanont, Chanchana; Wichainchai, Aree

    2013-01-01

    The CuFe1-xSnxO2 (x = 0.03, 0.05) delafossite samples have been synthesized by a solid-state reaction to investigate electrical and optical properties of the transparent conducting oxide materials. Crystal structure was characterized by XRD. The electrical conductivity and Seebeck coefficient were measured in the high temperature range of 300 to 960 K, while the Hall coefficient, XPS, and UV-VIS-NIR spectra were analyzed at room temperature. The XRD peaks of the samples indicate the delafossite structure phase, and the XPS spectra reveal the stable Sn2+-doping state. The Seebeck and Hall coefficient display a positive sign indicating the p-type conducting oxide. The optical allowed direct gap is 3.45 eV as a visible-transparent material. The activation energies for polaron hopping between Sn2+ sites and Fe3+ sites of 36 and 32 meV are obtained from the samples having x = 0.03 and 0.05, respectively. The CuFe1-xSnxO2 delafossite oxide compounds, of which the Fe3+ sites in the CuFeO2 are substituted by the Sn2+ ions, are p-type transparent conducting oxide materials. The activation energy is found to decrease with an increased in Sn content.

  11. The spin glass delafossite CuFe{sub 0.5}V{sub 0.5}O{sub 2}: a dipolar glass?

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Kiran; Maignan, Antoine; Simon, Charles; Hardy, Vincent; Pachoud, Elise; Martin, Christine, E-mail: antoine.maignan@ensicaen.fr [Laboratoire CRISMAT, CNRS UMR 6508, ENSICAEN, 6 Boulevard du Marechal Juin, 14050 Caen Cedex (France)

    2011-03-30

    The ferroelectric and spin glass properties of CuFe{sub 0.5}V{sub 0.5}O{sub 2} have been studied. Magnetization, ac magnetic susceptibility and specific heat measurements reveal a spin glass behavior (T{sub f} = 20.5 K) for this delafossite. In CuFeO{sub 2}, substitution of trivalent diamagnetic cations for Fe{sup 3+} is known to change the antiferromagnetic state and induce ferroelectricity. But partial occupation of the Fe{sup 3+} site by V{sup 3+} is responsible for disordered magnetism in CuFe{sub 0.5}V{sub 0.5}O{sub 2}. The dielectric permittivity shows a frequency dependence reminiscent of relaxor ferroelectrics in which different cations occupy the same crystallographic site. Polarization measurements show the existence of a ferroelectric state below T{sub f} with P{sub 5K{approx}}1.3 {mu}C m{sup -2}. These results point towards a relaxor-type ferroelectricity originating from a disordered array of magnetic cations. A clear coupling between electronic charges and spins is evidenced by the magnetodielectric effect.

  12. Ferromagnetism in reactive sputtered Cu0.96Fe 0.04O1-δ nanocrystalline films evidenced by anomalous Hall effect

    KAUST Repository

    Mi, Wenbo

    2011-03-14

    Cu0.96Fe0.04O1-δ nanocrystalline films were fabricated using reactive sputtering at different oxygen partial pressures (PO2). The electrical transport properties of the films were measured in a broad temperature range (10-300 K) under magnetic fields of up to 5T. Anomalous Hall effect (AHE) of up to 0.4μΩ cm was observed at 10 K and decreased to 0.2μΩ cm at 300 K. The characteristic AHE clearly indicated the existence of ferromagnetism in these materials. The AHE weakened as PO2 increased because the increasing PO2 reduced the fraction of Fe2+ ions, and consequently weakened the double exchange coupling between Fe2+-O2--Cu2+ in the materials. © 2011 The Japan Society of Applied Physics.

  13. Fenton-Like Catalysis and Oxidation/Adsorption Performances of Acetaminophen and Arsenic Pollutants in Water on a Multimetal Cu-Zn-Fe-LDH.

    Science.gov (United States)

    Lu, Hongtao; Zhu, Zhiliang; Zhang, Hua; Zhu, Jianyao; Qiu, Yanling; Zhu, Linyan; Küppers, Stephan

    2016-09-28

    Acetaminophen can increase the risk of arsenic-mediated hepatic oxidative damage; therefore, the decontamination of water polluted with coexisting acetaminophen and arsenic gives rise to new challenges for the purification of drinking water. In this work, a three-metal layered double hydroxide, namely, Cu-Zn-Fe-LDH, was synthesized and applied as a heterogeneous Fenton-like oxidation catalyst and adsorbent to simultaneously remove acetaminophen (Paracetamol, PR) and arsenic. The results showed that the degradation of acetaminophen was accelerated with decreasing pH or increasing H2O2 concentrations. Under the conditions of a catalyst dosage of 0.5 g·L(-1) and a H2O2 concentration of 30 mmol·L(-1), the acetaminophen in a water sample was completely degraded within 24 h by a Fenton-like reaction. The synthesized Cu-Zn-Fe-LDH also exhibited a high efficiency for arsenate removal from aqueous solutions, with a calculated maximum adsorption capacity of 126.13 mg·g(-1). In the presence of hydrogen peroxide, the more toxic arsenite can be gradually oxidized into arsenate and adsorbed at the same time by Cu-Zn-Fe-LDH. For simulated water samples with coexisting arsenic and acetaminophen pollutants, after treatment with Cu-Zn-Fe-LDH and H2O2, the residual arsenic concentration in water was less than 10 μg·L(-1), and acetaminophen was not detected in the solution. These results indicate that the obtained Cu-Zn-Fe-LDH is an efficient material for the decontamination of combined acetaminophen and arsenic pollution.

  14. Variation of magnetoimpedance of electrodeposited NiFe/Cu with deposition current density

    Science.gov (United States)

    Mishra, A. C.; Jha, A. K.

    2017-12-01

    An investigation about influence of deposition current density on electrodeposited magnetic film is reported in this paper. Ferromagnetic NiFe thin films were electrodeposited on copper wires of 100 μm diameter for various electrdepostion current densities ranging from 10 to 60 mA/cm2 maintaining equal thickness in all films. The composition of deposited film varied with deposition current density and in particular, a composition of Ni79Fe21 was achieved for a current density of 20 mA/cm2. The surface microstructure of the film deposited at the current density of 20 mA/cm2 was found to have excellent smoothness. The coercivity of the film was lowest and highest value of magnetoimpedance was measured for this film. The influence of current density on film composition and hence magnetic properties was attributed to the change of deposition mechanism.

  15. Simultaneous determination of Cd, Pb, Cu, Sb, Bi, Se, Zn, Mn, Ni, Co and Fe in water samples by differential pulse stripping voltammetry at a hanging mercury drop electrode.

    Science.gov (United States)

    Ghoneim, M M; Hassanein, A M; Hammam, E; Beltagi, A M

    2000-06-01

    A highly sensitive and selective voltammetric procedure is described for the simultaneous determination of eleven elements (Cd, Pb, Cu, Sb, Bi, Se, Zn, Mn, Ni, Co and Fe) in water samples. Firstly, differential pulse anodic stripping voltammetry (DPASV) with a hanging mercury drop electrode (HMDE) is used for the direct simultaneous determination of Cd, Pb, Cu, Sb and Bi in 0.1 M HCI solution (pH = 1) containing 2 M NaCl. Then, differential pulse cathodic stripping voltammetry (DPCSV) is used for the determination of Se in the same solution. Zn is subsequently determined by DPASV after raising the pH of the same solution to pH 4. Next, the pH of the medium is raised to pH 8.5 by adding NH3/NH4Cl buffer solution for the determination of Mn by DPASV. Ni and Co are determined in the same solution by differential pulse adsorptive stripping voltammetry (DPAdSV) after adding DMG (1 x 10(-4) M). Finally, 1 x 10(-5) M 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) is added to the solution for the determination of Fe by DPAdSV. The optimal conditions are described. Relative standard deviations and relative errors are calculated for the eleven elements at three different concentration levels. The lower detection limits for the investigated elements range from 1.11 x 10(-10) to 1.05 x 10(-9)M, depending on the element determined. The proposed analysis scheme was applied for the determination of these eleven elements in some ground water samples.

  16. Fe

    National Research Council Canada - National Science Library

    Ghasemzadeh, Mohammad Ali; Abdollahi-Basir, Mohammad Hossein; Babaei, Masoomeh

    2015-01-01

    An efficient and green approach for synthesizing chromeno[2,3-b]pyridine derivatives through one-pot three-component reactions of salicylaldehydes, thiols, and malononitrile has been developed by Fe 3 O 4...

  17. Cu(II), Fe(III) and Mn(II) combinations as environmental stress factors have distinguishing effects on Enterococcus hirae.

    Science.gov (United States)

    Vardanyan, Zaruhi; Trchounian, Armen

    2015-02-01

    Pollution by various heavy metals as environmental stress factors might affect bacteria. It was established that iron (Fe(III)), manganese (Mn(II)) and copper (Cu(II)) ion combinations caused effects on Enterococcus hirae that differed from the sum of the effects when the metals were added separately. It was shown that the Cu2+-Fe3+ combination decreased the growth and ATPase activity of membrane vesicles of wild-type E. hirae ATCC9790 and atpD mutant (with defective FoF1-ATPase) MS116. Addition of Mn2+-Fe3+ combinations within the same concentration range had no effects on growth compared to control (without heavy metals). ATPase activity was increased in the presence of Mn2+-Fe3+, while together with 0.2 mmol/L N,N'-dicyclohexylcarbodiimide (DCCD), ATPase activity was decreased compared to control (when only 0.2 mmol/L DCCD was present). These results indicate that heavy metals ion combinations probably affect the FOF1-ATPase, leading to conformational changes. Moreover the action may be direct or be mediated by environment redox potential. The effects observed when Fe3+ was added separately disappeared in both cases, which might be a result of competing processes between Fe3+ and other heavy metals. These findings are novel and improve the understanding of heavy metals ions effects on bacteria, and could be applied for regulation of stress response patterns in the environment. Copyright © 2014. Published by Elsevier B.V.

  18. Planar Hall effect bridge sensors with NiFe/Cu/IrMn stack optimized for self-field magnetic bead detection

    DEFF Research Database (Denmark)

    Henriksen, Anders Dahl; Rizzi, Giovanni; Hansen, Mikkel Fougt

    2016-01-01

    The stack composition in trilayer Planar Hall effect bridge sensors is investigated experimentally to identify the optimal stack for magnetic bead detection using the sensor self-field. The sensors were fabricated using exchange-biased stacks Ni80Fe20(tFM)/Cu(tCu)/Mn80Ir20(10 nm) with tFM = 10, 20....... The exchange bias field was found to decay exponentially with tCu and inversely with tFM. The reduced exchange field for larger values of tFM and tCu resulted in higher sensitivities to both magnetic fields and magnetic beads. We argue that the maximum magnetic bead signal is limited by Joule heating...

  19. Structural, catalytic and magnetic properties of Cu{sub 1-X}Co{sub X}Fe{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Briceno, Sarah, E-mail: sbriceno@ivic.gob.ve [Laboratorio de Fisica de la Materia Condensada, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Del Castillo, Hector [Laboratorio de Cinetica y Catalisis, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101-A (Venezuela, Bolivarian Republic of); Sagredo, V. [Laboratorio de Magnetismo, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101-A (Venezuela, Bolivarian Republic of); Bramer-Escamilla, Werner; Silva, Pedro [Laboratorio de Fisica de la Materia Condensada, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Cu{sub 1-X}Co{sub X}Fe{sub 2}O{sub 4} ferrite synthesized by sol-gel auto-combustion method. Black-Right-Pointing-Pointer Structural identification, magnetic and catalytic properties were investigated. Black-Right-Pointing-Pointer Characterization by TGA, DTA, XRD, SEM, TEM and VSM techniques. Black-Right-Pointing-Pointer Magnetic properties decrease with the increase of Cu{sup 2+} doping. Black-Right-Pointing-Pointer The selective conversion to N{sub 2} is higher for Cu-Co mixed ferrites. - Abstract: Copper substituted cobalt ferrite Cu{sub 1-X}Co{sub X}Fe{sub 2}O{sub 4} (0 {<=}x {<=} 1) have been synthesized using sol-gel auto combustion method with citric acid as fuel. Structural identification, magnetic and catalytic properties were investigated using thermogravimetric and differential thermal analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry and their application in the selective catalytic reduction of NOx were studied. Analysis of structural properties reveals that all samples have cubic spinel structure. Room temperature magnetic hysteresis measurements as a function of magnetic field infer that the magnetic properties decrease with Cu{sup 2+} doping which may be due to the difference of the magnetic moment of Cu{sup 2+} and Co{sup 2+} ions. The higher activity of the samples in NO selective reduction to N{sub 2} occurs at 350 Degree-Sign C, reaching a maximum of 38% NO conversion and 95% of selective conversion to N{sub 2}. The compositions containing both Cu{sup 2+} and Co{sup 2+} ions are more active to the products selectivity to N{sub 2}, suggesting a synergistic effect on the active surface of ferrite and the effect of Co{sup 2+} is more pronounced than Cu{sup 2+} towards NO conversion.

  20. Catalytic reduction of nitrate in secondary effluent of wastewater treatment plants by Fe(0) and Pd-Cu/γ-Al2O3.

    Science.gov (United States)

    Yun, Yupan; Li, Zifu; Chen, Yi-Hung; Saino, Mayiani; Cheng, Shikun; Zheng, Lei

    2016-01-01

    Total nitrogen, in which NO3(-) is dominant in the effluent of most wastewater treatment plants, cannot meet the requirements of the Chinese wastewater discharge standard (nitrate (NO3(-)) elimination attract considerable attention. In this study, reductant iron (Fe(0)) and γ-Al2O3 supported palladium-copper bimetallic catalysts (Pd-Cu/γ-Al2O3) were innovatively used for the chemical catalytic reduction of nitrate in wastewater. A series of specific operational conditions (such as mass ratio of Pd:Cu, catalyst amounts, reaction time and pH of solution) were optimized for nitrate reduction in the artificial solution, and then the selected optimal conditions were further applied for investigating the nitrate elimination of secondary effluent of a wastewater treatment plant in Beijing, China. Results indicated that a better catalytic performance (74% of nitrate removal and 62% of N2 selectivity) could be obtained under the optimal condition: 5 g/L Fe(0), 3:1 mass ratio (Pd:Cu), 4 g/L catalyst, 2 h reaction time and pH 5.1. It is noteworthy to point out that nitrogen gas (N2) predominated in the byproducts without another system to treat ammonium and nitrite. Therefore, the chemical catalytic reduction combining Fe(0) with Pd-Cu/γ-Al2O3 could be regarded as a better alternative for nitrate removal in wastewater treatment.