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Sample records for fe ru os

  1. Thermodynamics and superconductivity of Th7(Fe, Ru, Os, Co, Rh, Ir)3 system

    SciTech Connect

    Smith, James L; Lashley, Jason C; Volz, Heather M; Fisher, Robert A

    2008-01-01

    Expanding the temperature range of previous specific-heat measurements on the Th7(Fe, Ru, Os, Co, Rh, Ir)3 system, we measure the effect of transition-metal substitution on total entropy (S{sub 298 k}), electronic specific heat ({gamma}), and Debye temperature ({Theta}D). In addition we measure the pressure dependence, up to 10 kbar, of the superconducting transition.

  2. Structural, electronic, elastic and magnetic properties of RuFe{sub 3}N and OsFe{sub 3}N: A first principle study

    SciTech Connect

    Puvaneswari, S.; Priyanga, G. Sudha; Rajeswarapalanichamy, R. Santhosh, M.

    2015-06-24

    The structural, electronic, elastic and magnetic properties of the perovskite structure of RuFe{sub 3}N, and OsFe{sub 3}N have been reported using the VASP within the gradient generalized approximation. Total energy calculations are performed using both spin and non-spin polarized calculations and it is found that, at ambient pressure both RuFe{sub 3}N and OsFe{sub 3}N are stable in ferromagnetic phase. The electronic structure reveals that both RuFe{sub 3}N and OsFe{sub 3}N are metallic in nature at ambient pressure.

  3. Compressibility of Ru and Os in Comparison with Hcp ɛ -Fe; the lowest measured compressibility

    NASA Astrophysics Data System (ADS)

    Cynn, H.; Yoo, C.; Iota, V.; Baer, B.

    2001-12-01

    The hardness of a material is strongly correlated with its bulk modulus; thus, the search for superhard materials often becomes the search for very low compressibilities. Diamond is the hardest known material and has the highest known bulk modulus, B0 = 443 GPa (or the lowest compressibility, β = 0.226 Mbar-1). In this paper, we present surprising experimental findings that metallic elements like Os, Ir, and Ru are also good candidates for superhard materials based on their measured low compressibilities. We also present the pressure volume relationships of Ru, Os, and Ir to 70 GPa, in comparison with those of ɛ -Fe, W and C. The results are in a systematic agreement with the change of the bulk moduli and also with the first-principles electronic structure calculations. However, the c/a ratios of the 4,5d-transition metals show a slightly different trend from that of 3d ɛ -Fe at high pressures. Because of the similarity in electronic structure of these metals and Fe, the major constituent of the Earth's core, the EOS's and crystal structural parameters of the Group VIIIA transition metals reported in this paper are central to understanding the Earth's core mineral physics. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

  4. A comparative computationally study about the defined M(II) pincer hydrogenation catalysts (M = Fe, Ru, Os).

    PubMed

    Jiao, Haijun; Junge, Kathrin; Alberico, Elisabetta; Beller, Matthias

    2016-01-15

    The mechanism of acetonitrile and methyl benzoate catalytic hydrogenation using pincer catalysts M(H)2 (CO)[NH(C2 H4 PiPr2 )2 ] (1M) and M(H)(CO)[N(C2 H4 PiPr2 )2 ] (2M) (M = Fe, Ru, Os) has been computed at various levels of density functional theory. The computed equilibrium between 1Fe and 2Fe agrees perfectly with the experimental observations. On the basis of the activation barriers and reaction energies, the best catalysts for acetonitrile hydrogenation are 1Fe/2Fe and 1Ru/2Ru, and the best catalysts for methyl benzoate hydrogenation are 1Ru/2Ru. The best catalysts for the dehydrogenation of benzyl alcohol are 1Ru/2Ru. It is to note that the current polarizable continuum model is not sufficient in modeling the solvation effect in the energetic properties of these catalysts as well as their catalytic properties in hydrogenation reaction, as no equilibrium could be established between 1Fe and 2Fe. Comparison with other methods and procedures has been made. © 2015 Wiley Periodicals, Inc. PMID:25982241

  5. On the Highest Oxidation States of Metal Elements in MO4 Molecules (M = Fe, Ru, Os, Hs, Sm, and Pu).

    PubMed

    Huang, Wei; Xu, Wen-Hua; Schwarz, W H E; Li, Jun

    2016-05-01

    Metal tetraoxygen molecules (MO4, M = Fe, Ru, Os, Hs, Sm, Pu) of all metal atoms M with eight valence electrons are theoretically studied using density functional and correlated wave function approaches. The heavier d-block elements Ru, Os, Hs are confirmed to form stable tetraoxides of Td symmetry in (1)A1 electronic states with empty metal d(0) valence shell and closed-shell O(2-) ligands, while the 3d-, 4f-, and 5f-elements Fe, Sm, and Pu prefer partial occupation of their valence shells and peroxide or superoxide ligands at lower symmetry structures with various spin couplings. The different geometric and electronic structures and chemical bonding types of the six iso-stoichiometric species are explained in terms of atomic orbital energies and orbital radii. The variations found here contribute to our general understanding of the periodic trends of oxidation states across the periodic table. PMID:27074099

  6. X-ray microanalysis of aldehyde-fixed glycogen contrast-stained by OsVI . FeII and OsVI . RuIV complexes.

    PubMed

    de Bruijn, W C; van Buitenen, J M

    1980-11-01

    The composition of the contrast-donating complex of rat liver glycogen, nucleoplasm, erythrocytes, and mitochondria was established by X-ray microanalysis. In these compartments the presence of osmium and iron was shown qualitatively in tissue after glutaraldehyde fixation, treated with OsVIIIO4 plus K4FeII(CN)6 and in similar tissue treated with a combination of K2OsVIO4 plus K4FeII(CN)6. Osmium and ruthenium were detected in these compartments, in aldehyde-fixed tissue treated with mixtures containing K2RuIVL(CN)6 rather than K4FeII(CN)6. The iron detected in the glycogen, nucleoplasm, erythrocytes, and mitochondria of tissue treated with K2RuIV(CN)6 mixtures proved to derive from sources inside the electron microscope, and had to be considered an artifact. Quantitatively, the mean atomic ratios of osmium-to-iron and osmium-to-ruthenium were determined from spectra obtained by point analyses of the same compartments (glycogen, nucleoplasm, mitochondria, lipid droplets, and erythrocytes). After correction of the spectra for the instrumental iron contribution, the osmium-to-iron and osmium-to-ruthenium ratios in the glycogen were about 1:3 for tissue treated with those combinations including K2OsVIO4. In the other compartments, the osmium-to-iron and osmium-to-ruthenium ratios were virtually 1:0. For Os-VIIIO4 in combination with potassium ferrouscyanide however the osmium-to-iron ratio was 1:7 in the glycogen and 1:5 in all other compartments. OsVIIIO4 was combined with potassium ruthenium-cyanide, the osmium-to-ruthenium ratio was 1:2 in the glycogen and 2:1 in the other compartments. These results support our view that the selective glycogen contrast is obtained by complex formation. PMID:6159393

  7. (1)H NMR assignment corrections and (1)H, (13)C, (15)N NMR coordination shifts structural correlations in Fe(II), Ru(II) and Os(II) cationic complexes with 2,2'-bipyridine and 1,10-phenanthroline.

    PubMed

    Pazderski, Leszek; Pawlak, Tomasz; Sitkowski, Jerzy; Kozerski, Lech; Szłyk, Edward

    2010-06-01

    (1)H, (13)C and (15)N NMR studies of iron(II), ruthenium(II) and osmium(II) tris-chelated cationic complexes with 2,2'-bipyridine and 1,10-phenanthroline of the general formula [M(LL)(3)](2+) (M = Fe, Ru, Os; LL = bpy, phen) were performed. Inconsistent literature (1)H signal assignments were corrected. Significant shielding of nitrogen-adjacent protons [H(6) in bpy, H(2) in phen] and metal-bonded nitrogens was observed, being enhanced in the series Ru(II) --> Os(II) --> Fe(II) for (1)H, Fe(II) --> Ru(II) --> Os(II) for (15)N and bpy --> phen for both nuclei. The carbons are deshielded, the effect increasing in the order Ru(II) --> Os(II) --> Fe(II). PMID:20474023

  8. Muon-spin-relaxation and inelastic neutron scattering investigations of the caged-type Kondo semimetals: CeT2Al10 (T = Fe, Ru and Os)

    NASA Astrophysics Data System (ADS)

    Adroja, D. T.; Hillier, A. D.; Muro, Y.; Takabatake, T.; Strydom, A. M.; Bhattacharyya, A.; Daoud-Aladin, A.; Taylor, J. W.

    2013-12-01

    Recently, Ce-based caged-type compounds with the general formula CeT2Al10 (T = Fe, Ru and Os) have generated considerable interest due to the Kondo semiconducting paramagnetic ground state (down to 40 mK) observed in CeFe2Al10 and anomalously high magnetic ordering temperature with spin gap formation at low temperatures in Kondo semimetals CeRu2Al10 and CeOs2Al10. The formation of long-range magnetic ordering out of the Kondo semiconducting/semimetallic state itself is extraordinary and these are the first examples of this enigmatic coexistence of electronic ground states. These compounds also exhibit strong anisotropy in magnetic and transport properties, which has been explained on the basis of single-ion crystal electric field anisotropy in the presence of strongly anisotropic hybridization between localized 4f-electron and conduction electrons. Furthermore, they also exhibit a remarkable modification of magnetic and transport properties with doping on Ce, or T or Al sites. In this article, we briefly discuss the bulk properties of these compounds, giving a detailed discussion on our muon-spin-relaxation (μSR) investigations and inelastic neutron scattering (INS) results. We present the μSR and the INS results of Ce(Ru1-xFex)2Al10 and CeOs2Al10 as well as the μSR results of NdFe2Al10, NdOs2Al10 and YFe2Al10 for comparison. The zero-field μSR spectra clearly reveal coherent two-frequency oscillations at low temperatures in CeT2Al10 (T = Ru and Os) and Ce(Ru1-xFex)2Al10 (x = 0.3-0.5), which confirms the long-range magnetic ordering with a reduced moment of the Ce. On the other hand, the μSR spectra of Ce(Ru1-xFex)2Al10 (x = 0.8 and 1) down to 1.2 and 0.04 K, respectively, exhibit a temperature independent Kubo-Toyabe (KT) term confirming a paramagnetic ground state. INS measurements on CeT2Al10 (T = Ru and Os) exhibit sharp inelastic excitations at 8 and 11 meV at 5 K due to an opening of a gap in the spin excitation spectrum. A spin gap of 8-12 meV at 7 K

  9. Thermodynamic and transport properties of single-crystalline UM Ga5 (M=Fe,Co,Ni,Ru,Rh,Pd,Os,Ir,Pt)

    NASA Astrophysics Data System (ADS)

    Moreno, N. O.; Bauer, E. D.; Sarrao, J. L.; Hundley, M. F.; Thompson, J. D.; Fisk, Z.

    2005-07-01

    We report the results of magnetic susceptibility, specific heat, and electrical resistivity measurements on UMGa5 (M=Fe,Co,Ni,Ru,Rh,Pd,Os,Ir,Pt) single crystals. Antiferromagnetic ordering was observed for M=Ni , Pd, and Pt, with ordering temperatures TN=80K , 28K , and 23.5K , respectively. For the UMGa5 compounds with transition metals from the Fe and Co columns, itinerant paramagnetic behavior is observed. The evolution of this behavior is discussed in terms of f -ligand interaction with an emphasis on the role played by f-d hybridization.

  10. 1H, 13C, 15N NMR coordination shifts in Fe(II), Ru(II) and Os(II) cationic complexes with 2,2':6',2″-terpyridine.

    PubMed

    Pazderski, Leszek; Pawlak, Tomasz; Sitkowski, Jerzy; Kozerski, Lech; Szlyk, Edward

    2011-05-01

    (1)H, (13)C and (15)N NMR studies of iron(II), ruthenium(II) and osmium(II) bis-chelated cationic complexes with 2,2':6',2″-terpyridine ([M(terpy)(2) ](2+) ; M = Fe, Ru, Os) were performed. Significant shielding of nitrogen-adjacent H(6) and deshielding of H(3'), H(4') protons were observed, both effects being mostly expressed for Fe(II) compounds. The metal-bonded nitrogens were shielded, this effect being much larger for the outer N(1), N(1″) than the inner N(1') atoms, and enhanced in the Fe(II) → Ru(II) → Os(II) series. PMID:21491480

  11. Structural, electronic, elastic, thermoelectric and thermodynamic properties of the NbMSb half heusler (M=Fe, Ru, Os) compounds with first principle calculations

    NASA Astrophysics Data System (ADS)

    Abid, O. Miloud; Menouer, S.; Yakoubi, A.; Khachai, H.; Omran, S. Bin; Murtaza, G.; Prakash, Deo; Khenata, R.; Verma, K. D.

    2016-05-01

    The structural, electronic, elastic, thermoelectric and thermodynamic properties of NbMSb (M = Fe, Ru, Os) half heusler compounds are reported. The full-potential linearized augmented plane wave (FP-LAPW) plus local orbital (lo) method, based on the density functional theory (DFT) was employed for the present study. The equilibrium lattice parameter results are in good compliance with the available experimental measurements. The electronic band structure and Boltzmann transport calculations indicated a narrow indirect energy band gap for the compound having electronic structure favorable for thermoelectric performance as well as with substantial thermopowers at temperature ranges from 300 K to 800 K. Furthermore, good potential for thermoelectric performance (thermopower S ≥ 500 μeV) was found at higher temperature. In addition, the analysis of the charge density, partial and total densities of states (DOS) of three compounds demonstrate their semiconducting, ionic and covalent characters. Conversely, the calculated values of the Poisson's ratio and the B/G ratio indicate their ductile makeup. The thermal properties of the compounds were calculated by quasi-harmonic Debye model as implemented in the GIBBS code.

  12. Photochemistry of the ion pairs Rh(bpy)T M(CN)6U (bpy = 2,2'-bipyridyl) with M = Fe, Ru, Os following outer-sphere metal to ligand charge-transfer excitation

    SciTech Connect

    Vogler, A.; Kunkely, H.

    1987-06-03

    Optical metal to ligand charge-transfer (MLCT) transitions play an important role in the photophysics and photochemistry of transition-metal complexes. This electronic transition is an intramolecular (inner-sphere) process. It involves the promotion of a d electron of the metal to an empty orbital of a ligand coordinated to this metal. MLCT transitions occur at low energies if the metal is a reducing one and the ligand has available empty low-energy orbitals. Typical examples are the complexes Ru(bpy)3S (bpy = 2,2'-bipyridyl) and M(CN)6U (M = Fe, Ru, Os). In the latter case MLCT excitation is associated with the generation of solvated electrons. They report here on intermolecular (outer-sphere) MLCT transitions and the photochemistry following this type of CT excitation. In this case the optical transition involves the promotion of an electron from the metal of one complex to the ligand of another complex. The ion pairs Rh(bpy)3S M(CN)6U with M = Fe, Ru, Os were selected for this study.

  13. Nucleophilic activation of coordinated carbon monoxide. Part 3. Hydroxide and methoxide reactions with the trinuclear clusters M/sub 3/(CO)/sub 12/ (M = Fe, Ru, or Os): implications with regard to catalysis of the water gas shift reaction

    SciTech Connect

    Gross, D.C.; Ford, P.C.

    1985-02-06

    Reported are quantitative investigations of the reactions of the triangular clusters M/sub 3/(CO)/sub 12/ (M = Fe, Ru, or Os) with methoxide ion in solution. In methanol under a CO atmosphere, both the osmium and ruthenium species form stable 1:1 methoxycarbonyl adducts (M/sub 3/(CO)/sub 12/ + NaOCH/sub 3/ in equilibrium (M/sub 3/(CO)/sub 11/(CO/sub 2/CH/sub 3/))Na); however, for the triiron analogue this adduct undergoes fragmentation to give Fe(CO)/sub 4/(CO/sub 2/CH/sub 3/)/sup -/. Initial adduct formation in each case occurs with an equilibrium constant of about 10/sup 3/ M/sup -1/. In mixed tetrahydrofuran/methanol solutions, K/sub eq/ for Ru/sub 3/(CO)/sub 11/(CO/sub 2/CH/sub 3/)/sup -/ is much larger, an indication of the greater activity of NaOCH/sub 3/ in the less protic solvent. Notably, in such solvent mixtures, the presence of excess methoxide also led to the formation of 2:1 adducts. Rates of adduct formation were examined by using stopped-flow kinetics techniques, and it was shown that in methanol the second-order rate constants (25/sup 0/C) are 11.3 x 10/sup 3/, 2.1 x 10/sup 3/, and 0.6 x 10/sup 3/ M/sup -1/ s/sup -1/ for Fe/sub 3/(CO)/sub 12/, Ru/sub 3/(CO)/sub 12/, and Os/sub 3/(CO)/sub 12/, respectively. Rates were much higher in the mixed THF(tetrahydro-furan)/CH/sub 3/OH solutions; for example, k/sub 1/ (25/sup 0/C) for Ru/sub 3/(CO)/sub 12/ is 2.0 x 10/sup 5/ M/sup -1/ s/sup -1/ in 90/10 THF/CH/sub 3/OH (v/v). Monosubstitution of the ruthenium cluster with (CH/sub 3/O)/sub 3/P markedly reduced the reactivity toward the anionic nucleophile. The reaction of the triruthenium species with hydroxide (Ru/sub 3/(CO)/sub 12/ + OH/sup -/ in equilibrium Ru/sub 3/(CO)/sub 11/(CO/sub 2/H)/sup -/ ..-->.. HRu/sub 3/(CO)/sub 11//sup -/ + CO/sub 2/) was also investigated. Analysis of the reaction kinetics leads to the conclusion that formation of the initial hydroxycarbonyl adduct is somewhat less favorable and is slower than the analogous reaction of

  14. The role of the [CpM(CO)2](-) chromophore in the optical properties of the [Cp2ThMCp(CO)2](+) complexes, where M = Fe, Ru and Os. A theoretical view.

    PubMed

    Cantero-López, Plinio; Le Bras, Laura; Páez-Hernández, Dayán; Arratia-Pérez, Ramiro

    2015-12-14

    The chemical bond between actinide and the transition metal unsupported by bridging ligands is not well characterized. In this paper we study the electronic properties, bonding nature and optical spectra in a family of [Cp2ThMCp(CO)2](+) complexes where M = Fe, Ru, Os, based on the relativistic two component density functional theory calculations. The Morokuma-Ziegler energy decomposition analysis shows an important ionic contribution in the Th-M interaction with around 25% of covalent character. Clearly, charge transfer occurs on Th-M bond formation, however the orbital term most likely represents a strong charge rearrangement in the fragments due to the interaction. Finally the spin-orbit-ZORA calculation shows the possible NIR emission induced by the [FeCp(CO)2](-) chromophore accomplishing the antenna effect that justifies the sensitization of the actinide complexes. PMID:26523807

  15. Os-Ru-Ir and Os-(Ru)-Ir-Pt mineral phases from iron quartzites and weathered rocks of the Mikhailovka and Staryi Oskol KMA iron regions, central Russia

    NASA Astrophysics Data System (ADS)

    Chernyshov, N. M.; Ponamareva, M. M.

    2015-02-01

    Numerous natural Os-Ir-Ru and Os-Ir-Ru-Pt alloys have been found in iron quartzites and their weathered rocks. The Ir-Os alloys in the Mikhailovka and Staryi Oskol KMA iron regions are characterized by the densest hexagonal packing. Almost all of them contain a low amount of Fe and Ni at a relatively higher amount of Pt, Ru, and, locally, Rh. The highest Rh contents are typical of minerals with Ir dominant over Os or with a high Pt content.

  16. Spin-State Effects on the Thermal Dihydrogen Release from Solid-State [MH(η(2)-H 2)dppe2](+) (M = Fe, Ru, Os) Organometallic Complexes for Hydrogen Storage Applications.

    PubMed

    Abrecht, David G; Muñoz, Jorge A; Smith, Hillary L; Fultz, Brent

    2014-01-30

    Mössbauer spectroscopy, experimental thermodynamic measurements, and computational studies were performed to investigate the properties of molecular hydrogen binding to the organometallic fragments [MHdppe2](+) (M = Fe, Ru, Os; dppe =1,2-bis(diphenylphosphino)ethane) to form the dihydrogen complex fragments [MH(η(2)-H2)dppe2](+). Mössbauer spectroscopy showed that the dehydrogenated complex [FeHdppe2](+) adopts a geometry consistent with the triplet spin state, transitioning to a singlet state complex upon addition of the dihydrogen molecule in a manner similar to the previously studied dinitrogen complexes. From simulations, this spin transition behavior was found to be responsible for the strong binding behavior experimentally observed in the iron complex. Spin-singlet to spin-singlet transitions were found to exhibit thermodynamics consistent with the 5d > 3d > 4d binding trend observed for other transition metal dihydrogen complexes. Finally, the method for distinguishing between dihydrogen and dihydride complexes based on partial quadrupole splittings observed in Mössbauer spectra was confirmed, providing a tool for further characterization of these unique species for Mössbauer active compounds. PMID:24803973

  17. Spin-State Effects on the Thermal Dihydrogen Release from Solid-State [MH(η2-H2)dppe2]+ (M = Fe, Ru, Os) Organometallic Complexes for Hydrogen Storage Applications

    PubMed Central

    2015-01-01

    Mössbauer spectroscopy, experimental thermodynamic measurements, and computational studies were performed to investigate the properties of molecular hydrogen binding to the organometallic fragments [MHdppe2]+ (M = Fe, Ru, Os; dppe =1,2-bis(diphenylphosphino)ethane) to form the dihydrogen complex fragments [MH(η2-H2)dppe2]+. Mössbauer spectroscopy showed that the dehydrogenated complex [FeHdppe2]+ adopts a geometry consistent with the triplet spin state, transitioning to a singlet state complex upon addition of the dihydrogen molecule in a manner similar to the previously studied dinitrogen complexes. From simulations, this spin transition behavior was found to be responsible for the strong binding behavior experimentally observed in the iron complex. Spin-singlet to spin-singlet transitions were found to exhibit thermodynamics consistent with the 5d > 3d > 4d binding trend observed for other transition metal dihydrogen complexes. Finally, the method for distinguishing between dihydrogen and dihydride complexes based on partial quadrupole splittings observed in Mössbauer spectra was confirmed, providing a tool for further characterization of these unique species for Mössbauer active compounds. PMID:24803973

  18. Ru, Re, Os, Pt and Au in iron meteorites

    NASA Technical Reports Server (NTRS)

    Pernicka, Ernst; Wasson, John T.

    1987-01-01

    Neutron activation analysis is used to ascertain the proportions of Ru, Re, Os, and Pt refractory siderophiles, and moderately volatile Au, in 41 iron meteorites. The Ni-element trends defined for groups IID and IIIF support a magmatic origin; in addition, the results obtained for groups IAB and IIICD contrast with trends observed in magmatic groups, where the Ru and Pt slopes are substantially less steep. In group IIIAB, at Ni concentrations above 90 mg/g, the steep decrease of Re, Os, and Ir with Ni levels off, and the interelement ratios exhibit considerable scatter. These observations may be explained in terms of the contamination of the residual molten core with small amounts of late primitive melts draining from the mantle.

  19. XPS surface study of nanocrystalline Ti Ru Fe materials

    NASA Astrophysics Data System (ADS)

    Suñol, J. J.; Bonneau, M. E.; Roué, L.; Guay, D.; Schulz, R.

    2000-02-01

    The surface properties of Ti:Ru:Fe (2- x:1+ x/2:1+ x/2) (with x=0, 0.25, 0.5, 0.75, and 1) and Ti:Ru:Fe:O (2:1:1: w) (with w=0.0, 0.5, 1.0, 1.5, and 2.0) have been determined by X-ray photoelectron spectroscopy (XPS) in both their as-milled state and after being in contact with a chlorate oxidizing solution. The O surface concentrations of both sets of samples are almost identical, indicating that the O-free samples readily react with air. All samples in their as-milled state have an elemental Ti, Ru and Fe surface contents that closely follow that expected from their bulk composition, indicating that there is no surface enrichment in any of the elements. In the as-milled state, more than 90% of Ti and Fe atoms are in the highest possible oxidation state, while Ru is in the metallic state. Following immersion of the samples in an oxidizing chlorate electrolyte, the Ru surface concentration decreases by a factor of two. This is also accompanied by an increase in the oxidation state of the Ru atoms left at the surface from 0 to +4. From a comparison between the Ru 3 d5/2,3/2 core level spectra of the electrodes with those of crystalline and hydrated RuO 2, it is postulated that dissolution and re-deposition of Ru in the form of hydrated RuO 2 occurs at open circuit potential in the chlorate electrolyte. The consequences of these findings for the electrocatalytic activity of the electrodes in chlorate electrolyte are finally discussed.

  20. Electronic structure of Fe- vs. Ru-based dye molecules

    SciTech Connect

    Johnson, Phillip S.; Himpsel, F. J.; Cook, Peter L.; Zegkinoglou, Ioannis; Garcia-Lastra, J. M.; Rubio, Angel; Ruther, Rose E.; Hamers, Robert J.

    2013-01-28

    In order to explore whether Ru can be replaced by inexpensive Fe in dye molecules for solar cells, the differences in the electronic structure of Fe- and Ru-based dyes are investigated by X-ray absorption spectroscopy and first-principles calculations. Molecules with the metal in a sixfold, octahedral N cage, such as tris(bipyridines) and tris(phenanthrolines), exhibit a systematic downward shift of the N 1s-to-{pi}* transition when Ru is replaced by Fe. This shift is explained by an extra transfer of negative charge from the metal to the N ligands in the case of Fe, which reduces the binding energy of the N 1s core level. The C 1s-to-{pi}* transitions show the opposite trend, with an increase in the transition energy when replacing Ru by Fe. Molecules with the metal in a fourfold, planar N cage (porphyrins) exhibit a more complex behavior due to a subtle competition between the crystal field, axial ligands, and the 2+ vs. 3+ oxidation states.

  1. Si/NiFe seed layers for Ru intermediate layer in perpendicular magnetic recording tape media

    NASA Astrophysics Data System (ADS)

    Saemma, Gaku; Takahashi, Shota; Matsunuma, Satoshi; Inoue, Tetsutaro; Nakagawa, Shigeki

    2012-04-01

    Si/NiFe seed layers prepared at room temperature is effective to attain better c-axis orientation of Ru intermediate layer in the FeCoB/Ru/CoPtCr-SiO2 granular type recording tape media. The crystallinity and c-axis orientation of Ru layer with Si/NiFe seed layers were improved than that without Si/NiFe seed layer deposited on the laminated FeCoB SULs. When the Ru is thicker than 8 nm, Δθ50 of the CoPtCr-SiO2 recording layer shows small value of about 6.5°. Furthermore, even though the Ru thickness was only 3 nm, the Δθ50 retained comparatively small value of 8.0°. Si/NiFe layer is effective as a seed layer for the Ru intermediate layer.

  2. Diffusion, phase equilibria and partitioning experiments in the Ni-Fe-Ru system

    NASA Technical Reports Server (NTRS)

    Blum, Joel D.; Wasserburg, G. J.; Hutcheon, I. D.; Beckett, J. R.; Stolper, E. M.

    1989-01-01

    Results are presented on thin-film diffusion experiments designed to investigate phase equilibria in systems containing high concentrations of Pt-group elements, such as Ni-Fe-Ru-rich systems containing Pt, at temperatures of 1273, 1073, and 873 K. The rate of Ru diffusion in Ni was determined as a function of temperature, and, in addition, the degree of Pt and Ir partitioning between phases in a Ni-Fe-Ru-rich system and of V between phases in a Ni-Fe-O-rich system at 873 were determined. It was found that Pt preferentially partitions into the (gamma)Ni-Fe phase, whereas Ir prefers the (epsilon)Ru-Fe phase. V partitions strongly into Fe oxides relative to (gamma)Ni-Fe. These results have direct application to the origin and thermal history of the alloys rich in Pt-group elements in meteorites.

  3. Enhancement of magnetoresistance using CoFe/Ru/CoFe synthetic ferrimagnetic pinned layer in BiFeO{sub 3} based spin-valves

    SciTech Connect

    Naganuma, Hiroshi; Kubota, Miho; Inami, Nobuhito; Kawada, Yuki; Oogane, Mikihiko; Ando, Yasuo; Bae, In-Tae; Miyazaki, Takamichi; Mizukami, Shigemi; Han, X. F.

    2012-08-13

    SrTiO{sub 3} (100) sub/BiFeO{sub 3}/CoFe/Ru/CoFe/Cu/CoFe/Ta structure was prepared by a combination of chemical solution deposition and sputtering method, and followed by a systematical investigation for the structural, magnetic and magnetoresistance properties at room temperature (RT) as a function of CoFe and Ru thicknesses. It was revealed that introduction of synthetic CoFe/Ru/CoFe as a pinning layer increased the giant magentoresistance (MR) ratio to 8.3% at RT. This enhancement of MR ratio might be attributed to (i) the increase of pinning field, and (ii) suppression of the influence of the surface roughness of BiFeO{sub 3} by inserting the synthetic CoFe/Ru/CoFe layer.

  4. Marked enhancement of synthetic-antiferromagnetic coupling in subnanocrystalline FeCoB /Ru/FeCoB sputtered films

    NASA Astrophysics Data System (ADS)

    Hashimoto, Atsushi; Saito, Shin; Omori, Kazumi; Takashima, Hiroshi; Ueno, Tomonori; Takahashi, Migaku

    2006-07-01

    Extremely large flopping field and saturation field were realized in an FeCoB /Ru/FeCoB sputtered film by using subnanocrystalline (Fe65Co35)88B12 soft magnetic material with high saturation magnetization. Phenomenological analysis of synthetic-antiferromagnetic coupling revealed that the bilinear coupling energy induced in this film was three times larger than that in a Co91Zr4Nb5/Ru/Co91Zr4Nb5 film. This large bilinear coupling is thought to be the result of not only the suppression of ferromagnetic coupling due to the flat interface between the Ru and FeCoB layers but also the small Ru thickness for the first peak of 0.3nm caused by the Fe-rich soft magnetic material.

  5. Interlayer coupling in Ni80Fe20/Ru/Ni80Fe20 multilayer films: Ferromagnetic resonance experiments and theory

    NASA Astrophysics Data System (ADS)

    Liu, X. M.; Nguyen, Hoa T.; Ding, J.; Cottam, M. G.; Adeyeye, A. O.

    2014-08-01

    We present a systematic study of the static and dynamic magnetization behavior of interlayer-coupled Ni80Fe20(200Å)/Ru(tRu)/Ni80Fe20(100 Å) trilayers as a function of the Ru spacer layer thickness tRu. As tRu was varied in the range from 0 to 15.8 Å, we observe a strong antiferromagnetic (AFM) exchange coupling between the two ferromagnetic (FM) layers for tRu = 5 Å, which becomes weak for tRu = 10 Å. For tRu = 14.1 Å, the coupled magnetic system changes from AFM to FM ordering. Using broadband ferromagnetic resonance spectroscopy, we have probed the effects of the different coupling mechanisms on both the acoustic and optic magnetic modes. We found that the biquadratic exchange coupling has a negligible effect compared to Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange coupling, while the uniaxial anisotropy at the Ni80Fe20/Ru interfaces also plays an important role in determining the behaviors of the modes. A mode anticrossing phenomenon is observed when the RKKY exchange interaction term is above a critical value. A theoretical framework developed is in very good agreement with our experimental results.

  6. Electronic, magnetic, and transport properties of the isotypic aluminides SmT2Al10 (T = Fe, Ru)

    NASA Astrophysics Data System (ADS)

    Peratheepan, P.; Strydom, A. M.

    2015-03-01

    We report the results of a comprehensive physical and magnetic property study of the new isotypic aluminides SmT2Al10 (T = Fe, Ru). These two compounds are members of a rare-earth based system which has become an exemplary case study of the interplay of magnetism and correlated electron phenomena. SmFe2Al10 and SmRu2Al10 are found to order in a putative antiferromagnetic spin arrangement at TN = 14.5 K and 12.5 K, respectively. Moreover, SmRu2Al10 shows a further phase transition at TSR = 5 K which is likely due to spin reorientation. The susceptibility of SmFe2Al10 points to a valence instability of the Sm ionic state at intermediate temperatures well above TN. Electronic and thermal transport confirm that SmFe2Al10 undergoes an antiferromagnetic superzone gap formation below TN, whereas SmRu2Al10 suffers a lattice anomaly driven magnetoelastic coupling at TN. Below TN, the physical properties of SmT2Al10 (T = Fe, Ru) are governed by magnons with an antiferromagnetic spin-wave spectrum that reveals spin-gap opening. Our findings in this work have exposed a new anomalous correlated compound in the RT2Al10 series. SmFe2Al10 has a magnetic ordered ground state in spite of an unstable valence at higher temperature. This is comparable with CeRu2Al10, which is a unique and controversial Kondo insulator that orders antiferromagnetic at TN = 27 K. Among the series of rare-earth RT2Al10 compounds, the presented Sm compounds are two new members with anomalously high magnetic ordering temperatures, and it is envisaged that together with the two very well studied compounds CeRu2Al10 and CeOs2Al10 our presented studies will enable a broader approach towards understanding the fascinating properties of this materials class.

  7. Directional alignment of FeCo crystallites in Si/NiFe/Ru/FeCoB multilayer with high anisotropy field above 500 Oe.

    PubMed

    Hirata, Ken-Ichiro; Gomi, Shunsuke; Nakagawa, Shigeki

    2011-03-01

    In-plane magnetic anisotropy and crystal structure of FeCoB layer on Si/NiFe/Ru underlayer were investigated by using X-Ray Diffraction (XRD) measurement. A pole-figure measurement of XRD showed directionally tilted alignment of FeCo crystallites in Si/NiFe/Ru/FeCoB multilayered film with high in-plane anisotropy field H(k) but no directional alignment was found in FeCoB single layered film. The higher H(k) appeared in the Si/NiFe/Ru/FeCoB multilayered configuration with the thicker FeCoB layer. Since Ru crystallites in a multiunderlayer configuration exhibited no directional alignment, the surface structure of underlayer should be no main reason for the directional alignment of FeCo crystallites deposited on it. The dependence of hickness of FeCoB layer in Si/NiFe/Ru/FeCoB film on H(k) indicated that the in-plane magnetic anisotropy is caused by not only the structure of Ru underlayer but also oblique incidence effect of sputtered particles, which is attained in configuration of Facing Targets Sputtering (FTS) system. From these experimental results, remarkably high H(k) of 540 Oe was obtained. PMID:21449466

  8. Magnetic properties of Fe substituted SrRuO3 thin films and SrRuO3/Fe2O3 superlattices

    NASA Astrophysics Data System (ADS)

    Chmaissem, Omar; Kolesnik, Stanislaw; Dabrowski, Bogdan; Choi, Yongseong; Haskel, Daniel

    2010-03-01

    In recent years, SrRuO3 thin films have received considerable interest because of their potential for use as electrodes in oxide-based spintronic applications. SrRuO3 bulk materials are known to exhibit good room temperature thermal and electrical conductivity, a stable perovskite crystal structure, and itinerant ferromagnetic properties at temperatures below 163 K. To the best of our knowledge, attempts to enhance the magnetic properties of SrRuO3 through chemical substitutions of transition metal elements (e.g., Fe, Co, Mn, Cu, Zn, Ti, Cr, etc) at the Ru site, all failed except for the case of Cr substitutions in which TC was successfully raised to 190 K. In this work, we will demonstrate the drastically different effects of Fe on the magnetic properties of SrRuO3 bulk materials and thin films. We will also show and discuss the magnetic properties of SrRuO3/Fe2O3 superlattices. Work supported by the NSF (DMR-0706610) and the DOE-Office of Science (DEAC-02-06CH11357).

  9. A study of thermodynamic properties of dilute Fe-Ru alloys by 57Fe Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Idczak, R.; Konieczny, R.; Chojcan, J.

    2016-12-01

    The room temperature Mössbauer spectra of 57Fe were measured for Fe1- x Ru x solid solutions with x in the range 0.01 ≤ x ≤ 0.08. The obtained data were analysed in terms of short-range order parameter (SRO) and the binding energy E b between two ruthenium atoms in the studied materials using the extended Hrynkiewicz-Królas idea. The extrapolated value of E b for x = 0 was used to compute the enthalpy of solution H FeRu of Ru in Fe matrix. The result was compared with corresponding values given in the literature which were derived from experimental calorimetric data as well as with the value resulting from the cellular atomic model of alloys by Miedema. It was found that all the H FeRu values are negative or Ru atoms interact repulsively. At the same time, the Mössbauer data were used to determine values of the short-range order parameter α 1. For the as-obtained samples in which atoms are frozen-in high temperature state, close to the melting point, the negative α 1 values were found. The findings indicates ordering tendencies in such specimens. On the other hand, in the case of the annealed samples where the observed distributions of atoms should be frozen-in state corresponding to the temperature 700 K, the Fe1- x Ru x alloys with x ≥ 0.05 exhibit clustering tendencies (a predominance of Fe-Fe and Ru-Ru bonds), which manifest themselves by positive values of the calculated SRO parameter. The clustering process leads to a local increase in ruthenium concentration and nucleation of a new ruthenium-rich phase with the hcp structure.

  10. Correlation between microstructure and thermionic electron emission from Os-Ru thin films on dispenser cathodes

    SciTech Connect

    Swartzentruber, Phillip D.; John Balk, Thomas; Effgen, Michael P.

    2014-07-01

    Osmium-ruthenium films with different microstructures were deposited onto dispenser cathodes and subjected to 1000 h of close-spaced diode testing. Tailored microstructures were achieved by applying substrate biasing during deposition, and these were evaluated with scanning electron microscopy, x-ray diffraction, and energy dispersive x-ray spectroscopy before and after close-spaced diode testing. Knee temperatures determined from the close-spaced diode test data were used to evaluate cathode performance. Cathodes with a large (10-11) Os-Ru film texture possessed comparatively low knee temperatures. Furthermore, a low knee temperature correlated with a low effective work function as calculated from the close-spaced diode data. It is proposed that the formation of strong (10-11) texture is responsible for the superior performance of the cathode with a multilayered Os-Ru coating.

  11. Giant Magnetic Anisotropy of Co, Ru, and Os Adatoms on MgO (001) Surface.

    PubMed

    Ou, Xuedong; Wang, Hongbo; Fan, Fengren; Li, Zhengwei; Wu, Hua

    2015-12-18

    Large magnetic anisotropy energy (MAE) is desirable and critical for nanoscale magnetic devices. Here, using ligand-field level diagrams and density functional calculations, we well explain the very recent discovery [I. G. Rau et al., Science 344, 988 (2014)] that an individual Co adatom on a MgO (001) surface has a large MAE of more than 60 meV. More importantly, we predict that a giant MAE up to 110 meV could be realized for Ru adatoms on MgO (001), and even more for the Os adatoms (208 meV). This is a joint effect of the special ligand field, orbital multiplet, and significant spin-orbit interaction, in the intermediate-spin state of the Ru or Os adatoms on top of the surface oxygens. The giant MAE could provide a route to atomic scale memory. PMID:26722941

  12. Giant Magnetic Anisotropy of Co, Ru, and Os Adatoms on MgO (001) Surface

    NASA Astrophysics Data System (ADS)

    Ou, Xuedong; Wang, Hongbo; Fan, Fengren; Li, Zhengwei; Wu, Hua

    2015-12-01

    Large magnetic anisotropy energy (MAE) is desirable and critical for nanoscale magnetic devices. Here, using ligand-field level diagrams and density functional calculations, we well explain the very recent discovery [I. G. Rau et al., Science 344, 988 (2014)] that an individual Co adatom on a MgO (001) surface has a large MAE of more than 60 meV. More importantly, we predict that a giant MAE up to 110 meV could be realized for Ru adatoms on MgO (001), and even more for the Os adatoms (208 meV). This is a joint effect of the special ligand field, orbital multiplet, and significant spin-orbit interaction, in the intermediate-spin state of the Ru or Os adatoms on top of the surface oxygens. The giant MAE could provide a route to atomic scale memory.

  13. Ionization and photofragmentation of Ru3(CO)12 and Os3(CO)12

    NASA Astrophysics Data System (ADS)

    Schalk, Oliver; Josefsson, Ida; Richter, Robert; Prince, Kevin C.; Odelius, Michael; Mucke, Melanie

    2015-10-01

    In this paper, we use a combination of photoelectron spectroscopy, mass spectrometry, and density functional theory calculations to get a detailed understanding of valence single and double ionization and the subsequent dissociation processes. This is exemplified on benchmark systems, trimetallo-dodecacarbonyls M3(CO)12 with M = Ru, Os, where the energy remaining in the molecule after photoionization can be retrieved by measuring the degree of fragmentation of the molecular ion. The intensity of different mass peaks can thus be directly related to ionization cross sections obtained by photoelectron spectroscopy. We find that the M—CO dissociation energy rises as the number of CO ligands decreases due to dissociation. Moreover, ionization of the CO ligands has a higher cross section than that of the metal center for both single and double ionization. After advanced fragmentation, a CO bond can break and the carbon atom remains bonded to the metal core. In addition, we found that the valence ionization cross sections of M3(CO)12 are maximal at about 40 eV photon energy thus showing a more pronounced shape resonance than Ru and Os-complexes with a single metal atom center. Finally, an np → nd giant resonance absorption causes a significant increase of the ionization cross section above 50 eV for Ru3(CO)12.

  14. Ionization and photofragmentation of Ru3(CO)12 and Os3(CO)12.

    PubMed

    Schalk, Oliver; Josefsson, Ida; Richter, Robert; Prince, Kevin C; Odelius, Michael; Mucke, Melanie

    2015-10-21

    In this paper, we use a combination of photoelectron spectroscopy, mass spectrometry, and density functional theory calculations to get a detailed understanding of valence single and double ionization and the subsequent dissociation processes. This is exemplified on benchmark systems, trimetallo-dodecacarbonyls M3(CO)12 with M = Ru, Os, where the energy remaining in the molecule after photoionization can be retrieved by measuring the degree of fragmentation of the molecular ion. The intensity of different mass peaks can thus be directly related to ionization cross sections obtained by photoelectron spectroscopy. We find that the M-CO dissociation energy rises as the number of CO ligands decreases due to dissociation. Moreover, ionization of the CO ligands has a higher cross section than that of the metal center for both single and double ionization. After advanced fragmentation, a CO bond can break and the carbon atom remains bonded to the metal core. In addition, we found that the valence ionization cross sections of M3(CO)12 are maximal at about 40 eV photon energy thus showing a more pronounced shape resonance than Ru and Os-complexes with a single metal atom center. Finally, an np → nd giant resonance absorption causes a significant increase of the ionization cross section above 50 eV for Ru3(CO)12. PMID:26493905

  15. X-ray and neutron diffraction study of nanocrystalline Ti-Ru-Fe-O compounds

    SciTech Connect

    Blouin, M.; Guay, D.; Huot, J.; Schulz, R.; Swainson, I.P.

    1998-11-01

    The effect of adding oxygen on the structure of nanocrystalline Ti-Ru-Fe compounds obtained by high-energy ball-milling has been studied by X-ray and neutron diffraction using a Rietveld refinement analysis. It is shown that oxygen atoms readily oxidize Ti to form various types of titanium oxides depending on the oxygen content. In each case, a simple cubic structure (cP2-CsCl) is also formed during milling but with a concentration higher than expected on the basis of various reaction schemes. Through a detailed analysis of the neutron and X-ray diffraction peaks, it is shown that the 1a site of the CsCl-type unit cell is depleted from Ti atoms by preferential substitution with Fe. At high oxygen concentration, the alloy is a multiphase material containing Ti{sub 2{minus}x}Ru{sub 1+y}Fe{sub 1+z}, Ti oxides, Ru, and Fe.

  16. Characterization of Bimetallic Fe-Ru Oxide Nanoparticles Prepared by Liquid-Phase Plasma Method

    NASA Astrophysics Data System (ADS)

    Lee, Sung-Jin; Lee, Heon; Jeon, Ki-Joon; Park, Hyunwoong; Park, Young-Kwon; Jung, Sang-Chul

    2016-07-01

    The bimetallic Fe-Ru oxide nanoparticles were synthesized in the liquid-phase plasma (LPP) method which employed iron chloride and ruthenium chloride as precursors. The active species (OH·, Hα, Hβ, and OI) and the iron and ruthenium ions were observed in the plasma field created by the LPP process. The spherical-shaped bimetallic Fe-Ru oxide nanoparticles were synthesized by the LPP reaction, and the size of the particles was growing along with the progression of the LPP reaction. The synthesized bimetallic Fe-Ru oxide nanoparticles were comprised of Fe2O3, Fe3O4, RuO, and RuO2. Ruthenium had a higher reduction potential than iron and resulted in higher ruthenium composition in the synthesized bimetallic nanoparticles. The control of the molar ratio of the precursors in the reactant solution was found to be employed as a means to control the composition of the elements in bimetallic nanoparticles.

  17. Characterization of Bimetallic Fe-Ru Oxide Nanoparticles Prepared by Liquid-Phase Plasma Method.

    PubMed

    Lee, Sung-Jin; Lee, Heon; Jeon, Ki-Joon; Park, Hyunwoong; Park, Young-Kwon; Jung, Sang-Chul

    2016-12-01

    The bimetallic Fe-Ru oxide nanoparticles were synthesized in the liquid-phase plasma (LPP) method which employed iron chloride and ruthenium chloride as precursors. The active species (OH·, Hα, Hβ, and O(I)) and the iron and ruthenium ions were observed in the plasma field created by the LPP process. The spherical-shaped bimetallic Fe-Ru oxide nanoparticles were synthesized by the LPP reaction, and the size of the particles was growing along with the progression of the LPP reaction. The synthesized bimetallic Fe-Ru oxide nanoparticles were comprised of Fe2O3, Fe3O4, RuO, and RuO2. Ruthenium had a higher reduction potential than iron and resulted in higher ruthenium composition in the synthesized bimetallic nanoparticles. The control of the molar ratio of the precursors in the reactant solution was found to be employed as a means to control the composition of the elements in bimetallic nanoparticles. PMID:27456502

  18. Tuning of interlayer exchange coupling in Ni80Fe20/Ru/Ni80Fe20 nanowires

    NASA Astrophysics Data System (ADS)

    Liu, X. M.; Lupo, P.; Cottam, M. G.; Adeyeye, A. O.

    2015-09-01

    In this work, we demonstrate how the static and dynamic properties of Ni80Fe20/Ru/Ni80Fe20 nanowires can be tuned by varying the Ru spacer layer thickness. Specifically, changing the Ru thickness we have tuned the Ruderman-Kittel-Kasuya-Yosida exchange interaction, and thus the antiferromagnetic (AFM) strength between the Ni80Fe20 layers. We show that there is a strong correlation between the interlayer coupling and features in ferromagnetic resonance (FMR) modes. We found different mode-softening degree of the FMR curves as function of the strength of AFM coupling, together with a clear frequency gap at around zero field. These experimental results are in qualitative agreement with presented micromagnetic simulations that also include biquadratic interface exchange. Understanding these characteristics may offer insights for reconfigurable vertical magnetic logic devices and microwave filters.

  19. On the dynamical stability of ferromagnetic Ru and Os in the bct structure: a first-principles study

    NASA Astrophysics Data System (ADS)

    Cifuentes-Quintal, M. E.; de Coss, R.

    2015-08-01

    Recent theoretical studies have predicted magnetic states for Ru and Os in the body-centred tetragonal structure (bct) with ?. In this study, we present first principles calculations of the phonon dispersion for ferromagnetic Ru- and Os-bct along the epitaxial and uniaxial Bain paths, to evaluate their dynamical stability. The phonon dispersions were computed using the density functional perturbation theory, including the gradient corrections to the exchange-correlation functional within the plane-waves ultrasoft-pseudopotential approximation. The phonon dispersion for the local minimum in the Bain path with ? as well as the uniaxial and epitaxial strained structures are analysed. We find imaginary frequencies along different directions of the Brillouin zone, which indicates that both systems are dynamically unstable. Consequently, ferromagnetic Ru and Os in the bct with ? are not truly metastable phases.

  20. Pincer and diamine Ru and Os diphosphane complexes as efficient catalysts for the dehydrogenation of alcohols to ketones.

    PubMed

    Baratta, Walter; Bossi, Gianluca; Putignano, Elisabetta; Rigo, Pierluigi

    2011-03-14

    The ruthenium and osmium complexes [MCl(2)(diphosphane)(L)] (M=Ru, Os; L=bidentate amino ligand) and [MCl(CNN)(dppb)] (CNN=pincer ligand; dppb=1,4-bis-(diphenylphosphino)butane), containing the N−H moiety, have been found to catalyze the acceptorless dehydrogenation of alcohols in tBuOH and in the presence of KOtBu. The compounds trans-[MCl(2)(dppf)(en)] (M=Ru 7, Os 13; dppf=1,1'-bisdiphenylphosphino)ferrocene; en=ethylenediamine) display very high activity and different substrates, including cyclic and linear alcohols, are efficiently oxidized to ketones by using 0.8-0.04 mol % of catalyst. The effect of the base and the comparison of the catalytic activity of the Ru versus Os complexes are reported. The ruthenium complex 7 generally leads to a faster conversion into ketones with respect to the osmium complex 13, which displays better activity in the dehydrogenation of 5-en-3β-hydroxy steroids. The synthesis of new Ru and Os complexes [MCl(2)(PP)(L)] (PP=dppb, dppf; L=(±)-trans-1,2-diaminocyclohexane,2-(aminomethyl)pyridine, and 2-aminoethanol) of trans and cis configuration is also reported. PMID:21341330

  1. Regulation of charge delocalization in a heteronuclear Fe2 ru system by a stepwise photochromic process.

    PubMed

    Xu, Guang-Tao; Li, Bin; Wang, Jin-Yun; Zhang, Dao-Bin; Chen, Zhong-Ning

    2015-02-16

    Heteronuclear complexes FeCp2 -DTE-C≡C-Ru(dppe)2 Cl (1 o; dppe=1,2-bis(diphenylphosphino)ethane, Cp=cyclopentadienyl, DTE=dithienylethene) and FeCp2-DTE-C≡C-Ru(dppe)2-C≡C-DTE-FeCp2 (2 oo), with redox-active ferrocenyl and ruthenium centers separated by a photochromic DTE moiety, were prepared to achieve photoswitchable charge delocalization and Fe⋅⋅⋅Ru electronic communication. Upon UV-light irradiation of 2 oo, the Fe⋅⋅⋅Ru heterometallic electronic interaction is increasingly facilitated with stepwise photocyclization, 2 oo→2 co→2 cc; this is ascribed to the gradual increase in π-conjugated systems. The near-infrared absorptions in mixed-valence species [2 oo](+) /[2 co](+) /[2 cc](+) are gradually intensified following the conversion of [2 oo](+) →[2 co](+) →[2 cc](+) , which demonstrates that the extent of charge delocalization shows progressive enhancement with stepwise photocyclization. As revealed by electrochemical, spectroscopic, and theoretical studies, complex 2 exhibits nine switchable states through stepwise photochromic and reversible redox processes. PMID:25640650

  2. Evaluation of Fe and Ru Pincer-Type Complexes as Catalysts for the Racemization of Secondary Benzylic Alcohols.

    PubMed

    Bornschein, Christoph; Gustafson, Karl P J; Verho, Oscar; Beller, Matthias; Bäckvall, Jan-E

    2016-08-01

    Fe and Ru pincer-type catalysts are used for the racemization of benzylic alcohols. Racemization with the Fe catalyst was achieved within 30 minutes under mild reaction conditions, with a catalyst loading as low as 2 mol %. This reaction constitutes the first example of an iron-catalyzed racemization of an alcohol. The efficiency for racemization of the Fe catalyst and its Ru analogue was evaluated for a wide range of sec-benzylic alcohols. The commercially available Ru complex proved to be highly robust and even tolerated the presence of water in the reaction mixture. PMID:27311070

  3. Ru/FeCoB double layered film with high in-plane magnetic anisotropy field of 500 Oe

    NASA Astrophysics Data System (ADS)

    Hirata, Ken-ichiro; Hashimoto, Atsuto; Matsuu, Toshimitsu; Nakagawa, Shigeki

    2009-04-01

    FeCoB layers prepared on Ru underlayer possess a high saturation magnetization Ms and a high in-plane magnetic anisotropy filed Hk. Effects of preparation conditions were investigated. Low Ar gas pressure condition and thicker film thickness were effective to attain distortion of FeCo crystallite. As the crystallinity of Ru underlayer became higher, higher Hk was induced. The accumulation of anisotropic stress in the film caused by the oblique incidences of depositing atoms with high energy seems to be one of the important effects to attain high anisotropy field. It was succeeded to prepare the Ru/FeCoB film with high Hk of 500 Oe.

  4. σ-Aromaticity in polyhydride complexes of Ru, Ir, Os, and Pt.

    PubMed

    Jimenez-Izal, Elisa; Alexandrova, Anastassia N

    2016-04-28

    Transition-metal hydrides represent a unique class of compounds, which are essential for catalysis, organic synthesis, and hydrogen storage. In this work we study IrH5(PPh3)2, (RuH5(P(i)Pr3)2)(-), (OsH5(P(i)Pr3)2)(-), and OsH4(PPhMe2)3 polyhydride complexes, inspired by the recent discovery of the σ-aromatic PtZnH5(-) cluster anion. The distinctive feature of these molecules is that, like in the PtZnH5(-) cluster, the metal is five-fold coordinated in-plane, and holds additional ligands at the axial positions. This work shows that the unusual coordination in these compounds indeed can be explained by σ-aromaticity in the pentagonal arrangement, stabilized by the atomic orbitals on the metal. Based on this newly elucidated bonding principle, we additionally propose a new family of polyhydrides that display a uniquely high coordination. We also report the first indications of how aromaticity may impact the reactivity of these molecules. PMID:26414992

  5. Superlattice CoCrPt/Ru/CoFe structure fabricated by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Hu, X. F.; Liang, Q.; Li, H. Q.; He, X. X.; Wang, Xiaoru; Zhang, W.

    2006-04-01

    The synthetic antiferromagnets (SAF) have been used in spin-valve sensor in data storage industry [1]. We report a new hard/Ru/soft sandwich structure (SHBL) fabricated by pulsed lased deposition to replace current single layer structure for information recording application. SHBL consists of two magnetic layers separated by thin nonmagnetic layers, typically with Ru layers of 0.7-1.2 nm, through which antiferromagnetic coupling is induced. Varying the relative thickness of the magnetic layers, the spacer layers, and the type of magnetic materials can alter magnetic properties of CoCrPt/Ru/CoFe superlattice. The coercivity Hc and grain size of magnetic layer is also dependent on the laser fluence. High laser fluence results in both small grain size and high Hc. The observed phenomena are related to high quenching and deposition rates during PLD at high fluence, resulting in more pronounced phase segregation.

  6. Pair distribution function analysis of La(Fe{sub 1−x}Ru{sub x})AsO compounds

    SciTech Connect

    Martinelli, A.; Palenzona, A.; Ferdeghini, C.; Mazzani, M.; Bonfa', P.; Allodi, G.

    2014-12-15

    The local structures of La(Fe{sub 1−x}Ru{sub x})AsO (0.00≤x≤0.80) compounds were investigated by means of pair distribution function analysis at room temperature; as a result, no phase separation or clustering takes place. Local distortions are no longer correlated beyond ∼15 Å for both pure and substituted samples, indicating that the presence of Ru atoms does not determine a notable variation in the length scale of the local distortion. Different types of short range correlation between Fe and Ru atoms do not produce significant changes in the pair distribution function. - Graphical abstract: Fe–As and Ru–As bond length distributions as obtained by pair distribution function analysis of La(Fe{sub 0.70}Ru{sub 0.30})AsO; As atoms (purple spheres) undergo a random shifting around their crystallographic positions (red spheres: Fe/Ru atoms). - Highlights: • No phase separation or clustering takes place in La(Fe{sub 1−x}Ru{sub x})AsO solid solutions. • Local distortions are no longer correlated beyond ∼15 Å. • Ru displays a tendency towards local enrichment in the transition metal sublattice.

  7. Ru/FeCoB crystalline soft magnetic underlayers with high anisotropy field for CoPtCr-SiO2 granular perpendicular magnetic recording media

    NASA Astrophysics Data System (ADS)

    Matsuu, Toshimitsu; Hirata, Ken-ichiro; Hashimoto, Atsuto; Matsunuma, Satoshi; Inoue, Tetsutaro; Doi, Tsugihiro; Nakagawa, Shigeki

    2009-04-01

    Ru/FeCoB/Ru/CoPtCr-SiO2 films were fabricated as perpendicular magnetic recording media with crystalline soft magnetic underlayer (SUL). Ru/FeCoB layers possessed high in-plane anisotropy field Hk of 400 Oe and a bcc-FeCo (110) orientation. Crystalline orientation of the FeCoB in the SUL affected on a crystallite growth of a Ru intermediate layer deposited on it and on crystallite orientation of the CoPtCr-SiO2 film deposited on the Ru intermediate layer. Ru/CoPtCr-SiO2 films without Ru/FeCoB SULs exhibited a random orientation of Ru crystallites and the in-plane magnetic anisotropy. On the other hand, Ru/CoPtCr-SiO2 films deposited on the Ru/FeCoB SULs exhibited (001) preferential orientations of the CoPtCr as well as the Ru intermediate layer and possessed perpendicular magnetic anisotropy. It was confirmed that the improvement of a bcc-FeCo (110) orientation in the SUL was effective to the improvement of a hcp-Ru (001) orientation. At the media for an intermediate layer thickness of 5 nm, the similar magnetic properties as that of 30 nm were obtained. It indicated that the application of a crystalline SUL promoted the reduction in the intermediate layer thickness.

  8. Magnetization reversal and negative volume thermal expansion in Fe doped Ca2RuO4

    NASA Astrophysics Data System (ADS)

    Qi, T. F.; Yuan, S. J.; Ye, F.; Chi, S.; Terzic, J.; Zhang, H.; Zhao, Z.; Liu, X.; Parkin, S.; Mao, W. L.; Cao, G.

    We report structural, magnetic, transport and thermal properties of single-crystal Ca2Ru1-xFexO4 (0 <= x <= 0.2) as functions of pressure, magnetic field and temperature. The central findings of this work are a pronounced magnetization reversal and a negative thermal expansion that are induced by Fe doping. Our results including neutron diffraction data suggest that the magnetization reversal is primarily a result of different temperature dependences of two antiparallel, competing Ru and Fe sublattices and that the negative thermal expansion is achieved via magnetic and metal-insulator transitions. We will present and discuss our results with comparison drawn with relevant systems. This work was supported by the NSF via Grant No. DMR-1265162.

  9. Spin density wave (SDW) transition in Ru doped BaFeAs{sub 2} investigated by AC steady state calorimetry

    SciTech Connect

    Vinod, K. Sharma, Shilpam; Sundar, C. S.; Bharathi, A.

    2015-06-24

    Heat capacity measurements were done on sub-micron sized BaFe{sub 2−x}Ru{sub x}As{sub 2} single crystals using thin film membrane based the AC steady state calorimetry technique. Noticeable thermal hysteresis is observed in the heat capacity of the BaFe{sub 2−x}Ru{sub x}As{sub 2} during cooling and warming cycles, indicating first order nature of the SDW transition.

  10. Modifying exchange-spring behavior of CoPt/NiFe bilayer by inserting a Pt or Ru spacer

    SciTech Connect

    Hsu, Jen-Hwa Tsai, C. L.; Lee, C.-M.; Saravanan, P.

    2015-05-07

    We herein explore the possibility of obtaining tunable tilted magnetic anisotropy in ordered-CoPt (5 nm)/NiFe(t{sub NiFe}) bilayers through modifying their exchange spring behavior by inserting Pt and Ru-spacers. The tuning process of tilt angle magnetization of NiFe-layer was systematically investigated by varying the Pt or Ru thickness (t{sub Pt} or t{sub Ru}) from 0 to 8 nm at different thicknesses of NiFe (t{sub NiFe} = 1.5, 4.0, and 6.0 nm). Polar magneto-optic Kerr effect (p-MOKE) studies reveal that the bilayers grown in absence of spacers exhibit almost a rectangular hysteresis loop. With the insertion of Pt-spacer, the loop becomes more and more tilted as t{sub Pt} increases; whereas, in the case of Ru-spacer, the nature of the loops is not simply changing in one direction. The estimated SQR{sub ⊥} (= θ{sub r}/θ{sub s}) values from the p-MOKE loops are found to monotonically decrease with increasing t{sub Pt} when t{sub Pt} ≦ 4 nm. In contrast, in the case of Ru-spacer, an oscillatory behavior for the SQR{sub ⊥} values is apparent when t{sub Ru} ≦ 4 nm. As a result, an oscillatory tilted angle of NiFe spin configuration was obtained in the case of Ru-spacer; while a decoupling effect was prominent for the Pt-spacer. The results of present study reveal that the insertion of Pt and Ru-spacers as an appropriate means for realizing tunable tilted magnetic anisotropy in the CoPt/NiFe exchange springs.

  11. Strain-induced topological transition in SrRu2O6 and CaOs2O6

    DOE PAGESBeta

    Ochi, Masayuki; Arita, Ryotaro; Trivedi, Nandini; Okamoto, Satoshi

    2016-05-24

    The topological property of SrRu$_2$O$_6$ and isostructural CaOs$_2$O$_6$ under various strain conditions is investigated using density functional theory. Based on an analysis of parity eigenvalues, we anticipate that a three-dimensional strong topological insulating state should be realized when band inversion is induced at the A point in the hexagonal Brillouin zone. For SrRu$_2$O$_6$, such a transition requires rather unrealistic tuning, where only the $c$ axis is reduced while other structural parameters are unchanged. However, given the larger spin-orbit coupling and smaller lattice constants in CaOs$_2$O$_6$, the desired topological transition does occur under uniform compressive strain. Our study paves a waymore » to realize a topological insulating state in a complex oxide, which has not been experimentally demonstrated so far.« less

  12. Magnetic coupling in asymmetric FeCoV/Ru/FeNi trilayers

    NASA Astrophysics Data System (ADS)

    Wei, Yajun; Jana, Somnath; Brucas, Rimantas; Pogoryelov, Yevgen; Ranjbar, Mojtaba; Dumas, Randy K.; Warnicke, Peter; Åkerman, Johan; Arena, Dario A.; Karis, Olof; Svedlindh, Peter

    2014-05-01

    We have investigated the magnetic anisotropy and interlayer coupling in trilayer films of permendur(100 Å)/Ru/permalloy(100 Å), with the thickness of the Ru spacer varying from 0 to 200 Å. While the permendur/permalloy sample exhibits a small in-plane uniaxial magnetic anisotropy with Hu = 27 Oe, all trilayers are magnetically isotropic in-plane. Results from hysteresis loop and ferromagnetic resonance measurements were fitted to a micromagnetic model, with the results indicating that all the films are ferromagnetically coupled except the one with 10 Å Ru spacer, which shows antiferromagnetic coupling. The trilayers with Ru spacer layer thickness larger than 20 Å exhibit only very weak ferromagnetic coupling.

  13. Magnetism and electrical transport in Fe 0.9TM 0.1Si, TM=Co, Rh, Ru

    NASA Astrophysics Data System (ADS)

    Paschen, S.; Pushin, D.; Ott, H. R.; Young, D. P.; Fisk, Z.

    1999-01-01

    Our comparative study of magnetic and transport properties of Fe 0.9Co 0.1Si, Fe 0.9Rh 0.1Si, and Fe 0.9Ru 0.1Si indicates that the ferromagnetism previously observed in Fe 0.9Co 0.1Si is not due to localized magnetic moments residing on the Co atoms. It is rather the metallicity of the system which provides the formation of a ferromagnetic state.

  14. Ru Catalyst-Induced Perpendicular Magnetic Anisotropy in MgO/CoFeB/Ta/MgO Multilayered Films.

    PubMed

    Liu, Yiwei; Zhang, Jingyan; Wang, Shouguo; Jiang, Shaolong; Liu, Qianqian; Li, Xujing; Wu, Zhenglong; Yu, Guanghua

    2015-12-01

    The high oxygen storage/release capability of the catalyst Ru is used to manipulate the interfacial electronic structure in spintronic materials to obtain perpendicular magnetic anisotropy (PMA). Insertion of an ultrathin Ru layer between the CoFeB and Ta layers in MgO/CoFeB/Ta/MgO films effectively induces PMA without annealing. Ru plays a catalytic role in Fe-O-Ta bonding and isolation at the metal-oxide interface to achieve moderate interface oxidation. In contrast, PMA cannot be obtained in the sample with a Mg insertion layer or without an insertion layer because of the lack of a catalyst. Our work would provide a new approach toward catalyst-induced PMA for future CoFeB-based spintronic device applications. PMID:26565747

  15. Spin-orbit torque in Cr/CoFeAl/MgO and Ru/CoFeAl/MgO epitaxial magnetic heterostructures

    NASA Astrophysics Data System (ADS)

    Wen, Zhenchao; Kim, Junyeon; Sukegawa, Hiroaki; Hayashi, Masamitsu; Mitani, Seiji

    2016-05-01

    We study the spin-orbit torque (SOT) effective fields in Cr/CoFeAl/MgO and Ru/CoFeAl/MgO magnetic heterostructures using the adiabatic harmonic Hall measurement. High-quality perpendicular-magnetic-anisotropy CoFeAl layers were grown on Cr and Ru layers. The magnitudes of the SOT effective fields were found to significantly depend on the underlayer material (Cr or Ru) as well as their thicknesses. The damping-like longitudinal effective field (ΔHL) increases with increasing underlayer thickness for all heterostructures. In contrast, the field-like transverse effective field (ΔHT) increases with increasing Ru thickness while it is almost constant or slightly decreases with increasing Cr thickness. The sign of ΔHL observed in the Cr-underlayer devices is opposite from that in the Ru-underlayer devices while ΔHT shows the same sign with a small magnitude. The opposite directions of ΔHL indicate that the signs of spin Hall angle in Cr and Ru are opposite, which are in good agreement with theoretical predictions. These results show sizable contribution from SOT even for elements with small spin orbit coupling such as 3d Cr and 4d Ru.

  16. Magnetic, magnetocaloric properties and phenomenological model in amorphous Fe60Ru20B20 alloy

    NASA Astrophysics Data System (ADS)

    Boutahar, A.; Lassri, H.; Hlil, E. K.

    2015-11-01

    Magnetic, magnetocaloric properties and phenomenological model of amorphous Fe60Ru20B20 alloy are investigated in detail. The amorphous alloy has been synthesized using melt spinning method. The magnetic transition nature undergoes a second-order magnetic phase transition from ferromagnetic to paramagnetic states with a Curie temperature of 254 K. Basis on the thermodynamic Maxwell's relation, magnetic entropy change (-ΔSM) is calculated. Further, we also report a theoretical investigation of the magnetocaloric effect using a phenomenological model. The best model parameters and their variation with temperature and the magnetic field were determined. The theoretical predictions are found to agree closely with experimental measurements.

  17. Isotopic studies of Mg, Fe, Mo, RU and W in Fremdlinge from Allende refractory inclusions

    NASA Astrophysics Data System (ADS)

    Hutcheon, I. D.; Armstrong, J. T.; Wasserburg, G. J.

    1987-12-01

    This paper presents the first isotopic measurements, made with an ion microprobe, of Mg, Fe, Mo, Ru, and W in Fremdlinge and refractory metal nuggets from Allende meteorite. No non-mass-dependent deviations exceeding 1 percent from normal solar isotopic abundances were found for any of the elements analyzed, despite the unusual mineralogy of Fremdlinge and the extreme enrichment in refractory siderophile elements. It is concluded that the chemical, petrologic, and isotopic data on Fremdlinge are most plausibly interpreted in terms of the origin of Fremdlinge within the solar nebula.

  18. Moessbauer spectroscopic investigations of bimetallic FeCo, FeNi, and FeRu model catalysts supported on magnesium hydroxide carbonate

    SciTech Connect

    Nagorny, K.; Bubert, S.

    1987-11-01

    FeCo, FeNi, and FeRu alloys supported on basic magnesium carbonate have been prepared by precipitation from salt solutions at 340 K onto the support using ion exchange and have been subsequently annealed for 20 h under argon. The reduction, oxidation, and sintering behavior of the samples under H/sub 2/ or CO exposure has been investigated at 723 K by means of Moessbauer spectroscopy. The comparison of the resonance absorption areas of the spectra taken at 4 and 295 K allowed the calculation of the Debye temperatures and Debye-Waller factors of the different components. From the Debye-Waller factors the relative fractions could be extrapolated to the conditions at 0 K. The kinetics of the H/sub 2/ exposure showed an increase in the reduction velocity as well as in the degree of reduction in the sequence FeCo < FeNi < FeRu. Above a critical particle diameter a phase separation occurred because of the segregation of an iron-rich phase at the surface of the alloy particles. The kinetics of the CO exposure demonstrated that with FeCo clusters iron(III) surface oxide layers form, whereas with FeNi clusters iron(II) surface oxide layers are generated. FeCo clusters with a cobalt content of 25% form only unstable surface carbides, whereas clusters with a cobalt content of about 5% form stable bulk carbides. The velocity of carbide formation increases with decreasing particle size. Based on the present data a model is proposed which explains the behavior of FeMe/magnesium hydroxide carbonates catalysts in H/sub 2/ and CO atmospheres.

  19. Ru/FeCoB double layered film with high in-plane magnetic anisotropy field of 500 Oe

    SciTech Connect

    Hirata, Ken-ichiro; Hashimoto, Atsuto; Matsuu, Toshimitsu; Nakagawa, Shigeki

    2009-04-01

    FeCoB layers prepared on Ru underlayer possess a high saturation magnetization M{sub s} and a high in-plane magnetic anisotropy filed H{sub k}. Effects of preparation conditions were investigated. Low Ar gas pressure condition and thicker film thickness were effective to attain distortion of FeCo crystallite. As the crystallinity of Ru underlayer became higher, higher H{sub k} was induced. The accumulation of anisotropic stress in the film caused by the oblique incidences of depositing atoms with high energy seems to be one of the important effects to attain high anisotropy field. It was succeeded to prepare the Ru/FeCoB film with high H{sub k} of 500 Oe.

  20. Synthesis of Monomeric Fe(II) and Ru(II) Complexes of Tetradentate Phosphines

    SciTech Connect

    Jana, Barun; Ellern, Arkady; Pestovsky, Oleg; Sadow, Aaron; Bakac, Andreja

    2011-03-07

    rac-Bis[{l_brace}(diphenylphosphino)ethyl{r_brace}-phenylphosphino]methane (DPPEPM) reacts with iron(II) and ruthenium(II) halides to generate complexes with folded DPPEPM coordination. The paramagnetic, five-coordinate Fe(DPPEPM)Cl{sub 2} (1) in CD{sub 2}Cl{sub 2} features a tridentate binding mode as established by {sup 31}P{l_brace}{sup 1}H{r_brace} NMR spectroscopy. Crystal structure analysis of the analogous bromo complex, Fe(DPPEPM)Br{sub 2} (2) revealed a pseudo-octahedral, cis-{alpha} geometry at iron with DPPEPM coordinated in a tetradentate fashion. However, in CD{sub 2}Cl{sub 2} solution, the coordination of DPPEPM in 2 is similar to that of 1 in that one of the external phosphorus atoms is dissociated resulting in a mixture of three tridentate complexes. The chloro ruthenium complex cis-Ru({kappa}{sup 4}-DPPEPM)Cl{sub 2} (3) is obtained from rac-DPPEPM and either [RuCl{sub 2}(COD)]{sub 2} [COD = 1,5-cyclooctadiene] or RuCl{sub 2}(PPh{sub 3}){sub 4}. The structure of 3 in both the solid state and in CD{sub 2}Cl{sub 2} solution features a folded {kappa}{sup 4}-DPPEPM. This binding mode was also observed in cis-[Fe({kappa}{sup 4}-DPPEPM)(CH{sub 3}CN){sub 2}](CF{sub 3}SO{sub 3}){sub 2} (4). Addition of an excess of CO to a methanolic solution of 1 results in the replacement of one of the chloride ions by CO to yield cis-[Fe({kappa}{sup 4}-DPPEPM)Cl(CO)](Cl) (5). The same reaction in CH{sub 2}Cl{sub 2} produces a mixture of 5 and [Fe({kappa}{sup 3}-DPPEPM)Cl{sub 2}(CO)] (6) in which one of the internal phosphines has been substituted by CO. Complexes 2, 3, 4, and 5 appear to be the first structurally characterized monometallic complexes of {kappa}{sup 4}-DPPEPM.

  1. Ru(bpy)[sub 2][sup 2+] and Os(bpy)[sub 2][sup 2+] complexes of large polyaza cavity-shaped ligands

    SciTech Connect

    Thummel, R.P.; Williamson, D.; Hery, C. )

    1993-04-28

    The Friedlaender condensation of cyclic 1,2-diketones with 2-amino-5,6-dihydro-1,10-phenanthroline-3-carboxaldehyde provides a series of hexaaza cavity-shaped molecules 2a-c. Reaction with Ru(bpy)[sub 2]Cl[sub 2] (where bpy = 2,2[prime]-bipyridine) incorporates Ru(II) into a distal bidentate site. For ligands which are significantly nonplanar, a second Ru(II) or Os(II) nucleus can similarly be incorporated into the remaining distal site. The use of bpy-d[sub 8] as an auxilliary ligand simplifies the NMR spectra of the complexes and permits a detailed conformational analysis which is reinforced by an X-ray determination of the dinuclear complex [(bpy)[sub 2]Ru(2c)Ru(bpy)[sub 2

  2. Gibbs free energies of formation of RuO 2, IrO 2, and OsO 2: A high-temperature electrochemical and calorimetric study

    NASA Astrophysics Data System (ADS)

    O'Neill, Hugh St. C.; Nell, Johan

    1997-12-01

    The Gibbs free energies of formation of RuO 2, OsO 2 and IrO 2 have been determined by measuring the chemical potentials of oxygen (μO 2) defined by the reactions M + O 2 = MO 2, where M = Ru, Os. or Ir, using an electrochemical method with calcia-stabilized zirconia (CSZ) solid electrolytes. Measurements were attempted in the temperature ranges from ˜870 K to 1620, 1270, and 1415 K for the Ru, Os, and Ir equilibria, respectively, but inspection of the results reveals that equilibrium could not be established below ˜930 K for all three reactions. For Ru + RuO 2, the highest temperature data (above 1520 K) may be systematically affected by the onset of significant electronic conduction in the CSZ electrolyte, while the attempted measurements of the Os + OsO 2 equilibrium above 1190 K are obscured by the disproportionation of OsO 2 to gaseous Os oxides. The high temperature heat capacities at constant pressure ( Cp) of RuO 2 and IrO 2 were determined from 370 to 1070 K by differential scanning calorimetry. These data were combined with heat content measurements and low-temperature heat capacities from the literature, and fitted to an extended Maier-Kelley equation. The calorimetric data for RuO 2 and IrO 2, together with assessed data for Ru, Os, and Ir metals and estimated data for OsO 2, were used in a third law analysis of the electrochemical measurements. The values of μO 2 of the three equilibria were smoothed and filtered by the third-law analysis to yield the following equations which can be extrapolated to lower and higher temperatures as indicated: μO 2 ( Ru + RuO 2) = -324563 + 344.151 T-22.1155 T ln T (700 ⩽ T ⩽ 1800) μO 2 ( Os + OsO 2) = -300399 + 307.639 T-17.4819 T ln T (700 ⩽ T ⩽ 1500) μO 2 ( Ir + IrO 2) = -256518 + 295.854 T-15.2368 T ln T (700 ⩽ T ⩽ 1500) where μO 2 is in J mol -1, T is in K, the reference pressure for O 2 is 1 bar (10 5 Pa), and estimated accuracies are approximately 200 to 400 J mol -1. For Ru + RuO 2, the drift

  3. Significance of β-dehydrogenation in ethanol electro-oxidation on platinum doped with Ru, Rh, Pd, Os and Ir.

    PubMed

    Sheng, Tian; Lin, Wen-Feng; Hardacre, Christopher; Hu, P

    2014-07-14

    In the exploration of highly efficient direct ethanol fuel cells (DEFCs), how to promote the CO2 selectivity is a key issue which remains to be solved. Some advances have been made, for example, using bimetallic electrocatalysts, Rh has been found to be an efficient additive to platinum to obtain high CO2 selectivity experimentally. In this work, the mechanism of ethanol electrooxidation is investigated using the first principles method. It is found that CH3CHOH* is the key intermediate during ethanol electrooxidation and the activity of β-dehydrogenation is the rate determining factor that affects the completeness of ethanol oxidation. In addition, a series of transition metals (Ru, Rh, Pd, Os and Ir) are alloyed on the top layer of Pt(111) in order to analyze their effects. The elementary steps, α-, β-C-H bond and C-C bond dissociations, are calculated on these bimetallic M/Pt(111) surfaces and the formation potential of OH* from water dissociation is also calculated. We find that the active metals increase the activity of β-dehydrogenation but lower the OH* formation potential resulting in the active site being blocked. By considering both β-dehydrogenation and OH* formation, Ru, Os and Ir are identified to be unsuitable for the promotion of CO2 selectivity and only Rh is able to increase the selectivity of CO2 in DEFCs. PMID:24869778

  4. Effective band structure of Ru-doped BaFe2As2

    NASA Astrophysics Data System (ADS)

    Reticcioli, M.; Profeta, G.; Franchini, C.; Continenza, A.

    2016-02-01

    The use of lattice cells in real space that are arbitrarily larger than the primitive one, is nowadays more and more often required by ab initio calculations to study disorder, vacancy or doping effects in real materials. This leads, however, to complex band structures which are hard to interpret. Therefore an unfolding procedure is sought for in order to obtain useful data, directly comparable with experimental results, such as angle-resolved photoemission spectroscopy measurements. Here, we present an extension of the unfolding procedure recently implemented in the VASP code, which includes a projection scheme that leads to a full reconstruction of the primitive space. As a test case, we apply this newly implemented scheme to the Ru-doped BaFe2As2 superconducting compound. The results provide a clear description of the effective electronic band structure in the conventional Brillouin zone, highlighting the crucial role played by doping in this compound.

  5. Ordered vs. disordered perovskites; structural studies of Fe-doped SrIrO{sub 3} and SrRuO{sub 3}

    SciTech Connect

    Qasim, Ilyas; Blanchard, Peter E.R.; Liu, Samuel; Tang, Chunguang; Kennedy, Brendan J.; Avdeev, Maxim; Kimpton, Justin A.

    2013-10-15

    The structures of the two Fe containing perovskites Sr{sub 2}IrFeO{sub 6} and SrRu{sub 0.5}Fe{sub 0.5}O{sub 3} have been established using a combination of synchrotron and neutron diffraction methods. Sr{sub 2}IrFeO{sub 6} and SrRu{sub 0.5}Fe{sub 0.5}O{sub 3} are shown to be monoclinic I2/m and tetragonal I4/mcm respectively The former exhibits a rock-salt like ordering of the Fe and Ir cations and displays a sequence of phase transitions associated with the loss of the octahedral tilts upon heating; 12/m→I4/m→Fm3{sup ¯}m. The Fe and Ru cations are disordered in SrRu{sub 0.5}Fe{sub 0.5}O{sub 3} and this shows a single structural phase transition upon heating due to the loss of the in-phase tilts, viz. I4/mcm→Pm3{sup ¯}m. In both cases XANES measurements show partial oxidation of the Fe{sup 3+} to Fe{sup 4+}. The difference in the structures between the two is remarkable given the similar size of Ir{sup 5+} and Ru{sup 5+}, and this is reflected in their magnetic properties. - Graphical abstract: Sr{sub 2}IrFeO{sub 6} and SrRu{sub 0.5}Fe{sub 0.5}O{sub 3} are shown, using a combination of synchrotron and neutron diffraction, to be monoclinic I2/m with cation ordering and tetragonal I4/mcm with disordered Fe and Ir, respectively. Both undergo phase transitions upon heating due to the loss of the octahedral tilts. Display Omitted - Highlights: • Sr{sub 2}IrFeO{sub 6} shown to be monoclinic and shows the transitions upon heating I2/m→I4/m→ Fm3{sup ¯}m. • SrRu{sub 0.5}Fe{sub 0.5}O{sub 3} is tetragonal and shows a single I4/mcm→Pm3m transition upon heating. • The Fe and Ru cations are disordered in SrRu{sub 0.5}Fe{sub 0.5}O{sub 3} but ordered in Sr{sub 2}FeIrO{sub 6}. • XANES measurements show partial oxidation of the Fe{sup 3+} to Fe{sup 4+}.

  6. Theoretical study of the bonding in LaFe(2+), LaRu(2+) and YRu(2+)

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.

    1989-01-01

    The bonding in LaFe(2+) and LaRu(2+) involves nearly equal contributions from La(+) and La(2+). The second IP of Y is larger than that of La and this leads to predominantly Y(+) + Ru(+) character in the YRu(2+) wavefunction. The remarkable stability of these systems derives from multiple d-d bonds that lead to a bond-order of between two and three. Thus the ground states of these dications, which have relatively deep molecular wells and large barriers to dissociation, have essentially infinite lifetimes with respect to unimolecular decay.

  7. Large spin pumping effect in antisymmetric precession of Ni79Fe21/Ru/Ni79Fe21

    NASA Astrophysics Data System (ADS)

    Yang, H.; Li, Y.; Bailey, W. E.

    2016-06-01

    In magnetic trilayer structures, a contribution to the Gilbert damping of ferromagnetic resonance arises from spin currents pumped from one layer to another. This contribution has been demonstrated for layers with weakly coupled, separated resonances, where magnetization dynamics are excited predominantly in one layer and the other layer acts as a spin sink. Here, we show that trilayer structures in which magnetizations are excited simultaneously, antisymmetrically, show a spin-pumping effect roughly twice as large. The antisymmetric (optical) mode of antiferromagnetically coupled Ni79Fe21(8 nm)/Ru/Ni79Fe21(8 nm) trilayers shows a Gilbert damping constant greater than that of the symmetric (acoustic) mode by an amount as large as the intrinsic damping of Py ( Δα≃0.006 ). The effect is shown equally in field-normal and field-parallel to film plane geometries over 3-25 GHz. The results confirm a prediction of the spin pumping model and have implications for the use of synthetic antiferromagnets (SAF)-structures in GHz devices.

  8. Anisotropic elastic and vibrational properties of Ru2B3 and Os2B3: a first-principles investigation

    NASA Astrophysics Data System (ADS)

    Ozisik, Haci; Deligoz, Engin; Surucu, Gokhan; Bogaz Ozisik, Havva

    2016-07-01

    The structural, mechanical and lattice dynamical properties of Ru2B3 and Os2B3 have been investigated by using a first-principles method based on the density functional theory within the generalized gradient approximation. The single crystal elastic constants are numerically estimated using strain–stress approach. The polycrystalline aggregate elastic parameters are calculated from the single elastic constants via the Voigt–Reuss–Hill approximations. Subsequently, the ductility and brittleness are characterized with the estimation from Pugh’s rule (B/G) and Cauchy pressure. Additionally, the Debye temperature is calculated from the average elastic wave velocity obtained from bulk and shear moduli. The calculated parameters are consistent with the previous experimental and theoretical data. These borides are both mechanically and dynamically stable in the considered structure.

  9. Chemical pressure tuning of URu2Si2 via isoelectronic substitution of Ru with Fe

    NASA Astrophysics Data System (ADS)

    Das, Pinaki; Kanchanavatee, N.; Helton, J. S.; Huang, K.; Baumbach, R. E.; Bauer, E. D.; White, B. D.; Burnett, V. W.; Maple, M. B.; Lynn, J. W.; Janoschek, M.

    2015-02-01

    We have used specific heat and neutron diffraction measurements on single crystals of URu2 -xFexSi2 for Fe concentrations x ≤0.7 to establish that chemical substitution of Ru with Fe acts as "chemical pressure" Pc h as previously proposed by Kanchanavatee et al. [Phys. Rev. B 84, 245122 (2011), 10.1103/PhysRevB.84.245122] based on bulk measurements on polycrystalline samples. Notably, neutron diffraction reveals a sharp increase of the uranium magnetic moment at x =0.1 , reminiscent of the behavior at the "hidden order" to large-moment-antiferromagnetic phase transition observed at a pressure Px≈0.5 -0.7 GPa in URu2Si2 . Using the unit-cell volume determined from our measurements and an isothermal compressibility κT=5.2 ×10-3 GPa-1 for URu2Si2 , we determine the chemical pressure Pc h in URu2 -xFexSi2 as a function of x . The resulting temperature (T )-chemical pressure (Pc h) phase diagram for URu2 -xFexSi2 is in agreement with the established temperature (T )-external pressure (P ) phase diagram of URu2Si2 .

  10. Chemical pressure tuning of URu2 Si2 via isoelectronic substitution of Ru with Fe

    NASA Astrophysics Data System (ADS)

    Janoschek, Marc; Das, Pinaki; Kanchanavatee, Noravee; Helton, Joel S.; Huang, Kevin; Baumbach, Ryan E.; Bauer, Eric D.; Zhao, Yang; Ratcliff, William; White, Ben D.; Maple, M. Brian; Lynn, Jeff W.

    2015-03-01

    We have used specific heat and neutron diffraction measurements on single crystals of URu2-xFexSi2 for Fe concentrations x <= 0.7 to establish that isoelectronic substitution of Ru with Fe acts as ``chemical pressure'' Pch. Neutron diffraction reveals a sharp increase of the uranium magnetic moment at x = 0 . 1 , reminiscent of the ``hidden order'' (HO) to large moment antiferromagnetic (LMAFM) phase transition in URu2Si2. Using the unit cell volume, and the isothermal compressibility κT for URu2Si2, we determine Pch as function of x. The resulting temperature T-chemical pressure Pch phase diagram for URu2-xFexSi2 is in good agreement with the established temperature T-external pressure P phase diagram of URu2Si2. Thus, URu2-xFexSi2 provides a new opportunity to study the close relationship between the HO and LMAFM phases with methods that cannot be used under pressure, and may shed some new light on the on the elusive order parameter of the HO.

  11. Chemical pressure tuning of URu2Si2 via isoelectronic substitution of Ru with Fe

    DOE PAGESBeta

    Das, Pinaki; Kanchanavatee, N.; Helton, J. S.; Huang, K.; Baumbach, R. E.; Bauer, E. D.; White, B. D.; Burnett, V. W.; Maple, M. B.; Lynn, J. W.; et al

    2015-02-26

    We have used specific heat and neutron diffraction measurements on single crystals of URu2–xFexSi₂ for Fe concentrations x ≤ 0.7 to establish that chemical substitution of Ru with Fe acts as “chemical pressure” Pch as previously proposed by Kanchanavatee et al. [Phys. Rev. B 84, 245122 (2011)] based on bulk measurements on polycrystalline samples. Neutron diffraction reveals a sharp increase of the uranium magnetic moment at x = 0.1, reminiscent of the behavior at the “hidden order” to large moment antiferromagnetic (LMAFM) phase transition observed at a pressure Px ≈ 0.5-0.7 GPa in URu₂Si₂. Using the unit cell volume determinedmore » from our measurements and an isothermal compressibility κT = 5.2×10⁻³ GPa⁻¹ for URu₂Si₂, we determine the chemical pressure Pch in URu2-xFexSi₂ as a function of x. The resulting temperature T-chemical pressure Pch phase diagram for URu2-xFexSi₂ is in agreement with the established temperature T-external pressure P phase diagram of URu₂Si₂.« less

  12. Structural and magnetic properties of X12Y (X, Y=Fe, Co, Ni, Ru, Rh, Pd, and Pt) nanoalloys

    NASA Astrophysics Data System (ADS)

    Aguilera-Granja, F.; Longo, R. C.; Gallego, L. J.; Vega, A.

    2010-05-01

    We perform extensive ab initio density-functional calculations to investigate the structures and magnetic moments of the binary clusters X12Y (X, Y=Fe, Co, Ni, Ru, Rh, Pd, and Pt). Although all the binary clusters Fe12Y, Co12Y, Ru12Y, and Rh12Y, plus Ni12Y (Y=Rh, Pd, and Pt) and Pt12Y (Y=Ru, Rh, and Pd), retain, with more or less distortions, the structures of the corresponding pure X13 clusters, the remaining binary clusters (i.e., a significant number of 12 of all the 42 cases) adopt geometries different from those of the corresponding pure clusters. Independent of the peculiarities of each family of binary clusters, the binding energies of all the binary clusters X12Ru are bigger than those of the pure X13 clusters, while the binding energies of all the binary clusters X12Pd are smaller. The clusters investigated exhibit a variety of magnetic behaviors. In the case of Ni12Rh, we predict a remarkable magnetic cooperative phenomenon that can be attributed to electronic effects associated to the chemical environment through Ni-Rh hybridization.

  13. Theory of the metal-insulator transition in Pr Ru4 P12 and Pr Fe4 P12

    NASA Astrophysics Data System (ADS)

    Curnoe, S. H.; Harima, H.; Takegahara, K.; Ueda, K.

    2004-12-01

    All symmetry-allowed couplings between the 4f2 -electron ground state doublet of trivalent praseodymium in PrRu4P12 and PrFe4P12 and displacements of the phosphorus, iron, or ruthenium ions are considered. Two types of displacements can change the crystal lattice from body-centred cubic to simple orthorhombic or to simple cubic. The first type lowers the point group symmetry from tetrahedral to orthorhombic, while the second type leaves it unchanged, with corresponding space group reductions Im3¯→Pmmm and Im3¯→Pm3¯ , respectively. In former case, the lower point group symmetry splits the degeneracy of the 4f2 doublet into states with opposite quadrupole moment, which then leads to antiquadrupolar ordering, as in PrFe4P12 . Either kind of displacement may conspire with nesting of the Fermi surface to cause the metal-insulator or partial metal-insulator transition observed in PrFe4P12 and PrRu4P12 . We investigate this scenario using band-structure calculations, and it is found that displacements of the phosphorus ions in PrRu4P12 (with space-group reduction Im3¯→Pm3¯ ) open a gap everywhere on the Fermi surface.

  14. Structure and magnetic properties of FeRuGaSi multilayer thin films

    NASA Astrophysics Data System (ADS)

    Jagielinski, T. M.; Zeltser, A. M.; Brucker, C. F.

    1991-04-01

    The structure and magnetic properties of FeRuGaSi thin films used in very-high-frequency (150 MHz) recording head has been studied. The best soft magnetic properties, viz., coercivity of 0.2-0.3 Oe, permeability of 2000 at 1 MHz and 400-500 at 150 MHz, and magnetostriction of less than 10-6, were obtained after annealing at 450-500 °C. This magnetic behavior was attributed to the phase transformations and the increase in the grain size of the films occurring during the annealing process. Transmission electron diffraction revealed that B2 and/or DO3 ordered phases were formed in the films depending on the annealing temperature. However, good soft magnetic properties were associated with the formation of the B2 phase with low crystal anisotropy and saturation magnetostriction. These results are somewhat in contrast to what has been observed in Sendust, where magnetic softness is usually attributed to the formation of the DO3 phase.

  15. Relationship between the structure and soft magnetic properties of FeRuGaSi films

    NASA Astrophysics Data System (ADS)

    Zeltser, A. M.; Jagielinski, T. M.

    1991-11-01

    The effect of annealing on the structure and magnetic properties (coercivity, saturation magnetostriction, and initial permeability) of (FeRu)x(GaSi) films (x=2.5, 3.4, and 3.9) sputtered on MnNi-oxide and Li-silicate glass-ceramic substrates has been investigated. It is found that the best combination of soft magnetic properties (e.g., coercivity ≊0.3 Oe, permeability ≊1800 at 10 MHz, and magnetostriction < 1 × 10-6) is generally obtained after annealing between 450 and 500 °C independent of film composition, and subsequently deteriorate at higher annealing temperatures. This magnetic behavior is correlated with the crystal structure, grain size, and texture of the films as revealed by transmission electron microscopy and x-ray diffraction. It is found that after annealing, all films exhibit best soft magnetic properties when they consist of mostly the B2 phase and their magnetic softness decreases with the formation of the DO3 phase.

  16. The Disposition of Pt, Pd, Ir, Os, and Ru in Marine Sediments and the K/T Boundary

    NASA Technical Reports Server (NTRS)

    Lee, Cin-Ty; Wasserburg, Gerald; Kyte, Frank

    2003-01-01

    The marine record of platinum group elements (PGEs) and Os isotopic compositions provides information on different inputs of PGEs into the oceans. Some studies based on a smaller subset of the PGEs suggest that the PGEs may suffer post-depositional mobility during diagenesis. In some K/T boundary clays, Kyte and others showed that the relative abundances of Pt, Pd, Ir, and Os can differ significantly from chondritic, which is the signature expected from fallout of the meteorite impact. In some K/T boundary sections, elevated Ir concentrations are observed as far as 1 meter from the cm-thick boundary clay containing the meteoritic ejecta. The purpose of this study was to characterize Pt, Pd, Ir, Os, and Ru abundances in zones including the K/T boundary. We determined PGE abundances of boundary clays at two hemipelagic sites (Stevns Klint, Denmark and Caravaca, Spain) in which previous studies by Kyte and others showed that the Ir anomaly is confined to within a few cm. We also analyzed two pelagic Pacific sites: a boundary clay from the north Pacific (Hole 465A) characterized by a 0.5 m thick Ir anomaly and a transect across the K/T boundary from the south Pacific (Hole 596) where the Ir anomaly spans 2 m. The Stevns Klint, Caravaca, and north Pacific sites are characterized by abundant marls and limestones in the section, whereas the south Pacific site is dominated by clays. Samples were spiked with isotopic tracers, mixed with a flux, S and Ni, and equilibrated by fusion. PGEs were extracted from the Ni and analyzed on a Finnigan Element ICP-MS. We find that the narrow Caravaca and Stevns Klint boundary clays have relative PGE abundance patterns indistinguishable from chondritic values. The two Pacific sites were found to have nearly identical PGE patterns but have ratios at the peak, which differ from chondritic values as found earlier by Evans et al. The Pacific sites were found to have nearly identical PGE patterns but are extremely depleted in OS (Os/Ir = 0

  17. Exotic magnetism on the quasi-FCC lattices of the d3 double perovskites La2NaB'O6 (B' = Ru, Os)

    SciTech Connect

    Aczel, Adam A; Baker, Peter J.; Bugaris, Dan; Yeon, Jeongho; Zur Loye, Hans-Conrad; Guidi, T.; Adroja, D. T.

    2014-01-01

    We find evidence for long-range and short-range ($\\zeta$~$=$~70~\\AA~at 4~K) incommensurate magnetic order on the quasi-face-centered-cubic (FCC) lattices of the monoclinic double perovskites La$_2$NaRuO$_6$ and La$_2$NaOsO$_6$ respectively. Incommensurate magnetic order on the FCC lattice has not been predicted by mean field theory, but may arise via a delicate balance of inequivalent nearest neighbour and next nearest neighbour exchange interactions. In the Ru system with long-range order, inelastic neutron scattering also reveals a spin gap $\\Delta$~$\\sim$~2.75~meV. Magnetic anisotropy is generally minimized in the more familiar octahedrally-coordinated $3d^3$ systems, so the large gap observed for La$_2$NaRuO$_6$ may result from the significantly enhanced value of spin-orbit coupling in this $4d^3$ material.

  18. Exotic Magnetism on the Quasi-fcc Lattices of the d3 Double Perovskites La2NaB'O6 (B'=Ru, Os)

    NASA Astrophysics Data System (ADS)

    Aczel, A. A.; Baker, P. J.; Bugaris, D. E.; Yeon, J.; zur Loye, H.-C.; Guidi, T.; Adroja, D. T.

    2014-03-01

    We find evidence for long-range and short-range (ζ =70 Å at 4 K) incommensurate magnetic order on the quasi-face-centered-cubic (fcc) lattices of the monoclinic double perovskites La2NaRuO6 and La2NaOsO6, respectively. Incommensurate magnetic order on the fcc lattice has not been predicted by mean field theory, but may arise via a delicate balance of inequivalent nearest neighbor and next nearest neighbor exchange interactions. In the Ru system with long-range order, inelastic neutron scattering also reveals a spin gap Δ ˜2.75 meV. Magnetic anisotropy is generally minimized in the more familiar octahedrally coordinated 3d3 systems, so the large gap observed for La2NaRuO6 may result from the significantly enhanced value of spin-orbit coupling in this 4d3 material.

  19. Low Temperature Hysteretic Behavior of the Interpenetrating 3-D Network Structured [Ru2(O2CMe)4]3[Fe(CN)6] Magnet

    SciTech Connect

    Haque, F.; Del barco, Enrique; Fishman, Randy Scott; Miller, Joel S.

    2013-01-01

    The low temperature hysteretic behavior between 40 mK and 4.8 K was obtained for [Ru2(O2CMe)4]3[Fe(CN)6]. The unusual constricted hysteretic behavior reported for isomorphous [Ru2(O2CMe)4]3[Cr(CN)6] was not observed. Instead, the [Ru2(O2CMe)4]3-[Fe(CN)6] exhibits a single hysteresis loop and a temperature dependence of the coercivity atypical for a ferrimagnetic ordering transition. The coercive field, constant below ~0.3 K (1.06 kOe), shows a rapid initial decrease below 1 K, to continue decreasing at a slower rate up to at least 4.8 K. In contrast to [Ru2(O2CMe)4]3[Cr(CN)6] which has antiferromagnetic coupling of the ferrimagnetic lattices, due to the reduced spin on the [FeIII(CN)6]3-, [Ru2(O2CMe)4]3[Fe(CN)6] ferromagnetic coupling of the ferrimagnetic lattices dominates for [Ru2(O2CMe)4]3[Fe(CN)6].

  20. Complex transition metal hydrides incorporating ionic hydrogen: thermal decomposition pathway of Na2Mg2FeH8 and Na2Mg2RuH8.

    PubMed

    Humphries, Terry D; Matsuo, Motoaki; Li, Guanqiao; Orimo, Shin-Ichi

    2015-03-28

    Complex transition metal hydrides have potential technological application as hydrogen storage materials, smart windows and sensors. Recent exploration of these materials has revealed that the incorporation of anionic hydrogen into these systems expands the potential number of viable complexes, while varying the countercation allows for optimisation of their thermodynamic stability. In this study, the optimised synthesis of Na2Mg2TH8 (T = Fe, Ru) has been achieved and their thermal decomposition properties studied by ex situ Powder X-ray Diffraction, Gas Chromatography and Pressure-Composition Isotherm measurements. The temperature and pathway of decomposition of these isostructural compounds differs considerably, with Na2Mg2FeH8 proceeding via NaMgH3 in a three-step process, while Na2Mg2RuH8 decomposes via Mg2RuH4 in a two-step process. The first desorption maxima of Na2Mg2FeH8 occurs at ca. 400 °C, while Na2Mg2RuH8 has its first maxima at 420 °C. The enthalpy and entropy of desorption for Na2Mg2TH8 (T = Fe, Ru) has been established by PCI measurements, with the ΔHdes for Na2Mg2FeH8 being 94.5 kJ mol(-1) H2 and 125 kJ mol(-1) H2 for Na2Mg2RuH8. PMID:25732233

  1. Contrasting effect of La substitution on the magnetic moment direction in the Kondo semiconductors Ce T2Al10 (T =Ru ,Os )

    NASA Astrophysics Data System (ADS)

    Adroja, D. T.; Hillier, A. D.; Ritter, C.; Bhattacharyya, A.; Khalyavin, D. D.; Strydom, A. M.; Peratheepan, P.; Fâk, B.; Koza, M. M.; Kawabata, J.; Yamada, Y.; Okada, Y.; Muro, Y.; Takabatake, T.; Taylor, J. W.

    2015-09-01

    The opening of a spin gap in the orthorhombic compounds Ce T2Al10 (T =Ru andOs ) is followed by antiferromagnetic ordering at TN=27 and 28.5 K, respectively, with a small ordered moment (0.29 -0.34 μB ) along the c axis, which is not an easy axis of the crystal field (CEF). In order to investigate how the moment direction and the spin gap energy change with La doping in Ce1 -xLaxT2Al10 (T = Ru and Os) and also to understand the microscopic nature of the magnetic ground state, we here report on magnetic, transport, and thermal properties, neutron diffraction (ND), and inelastic neutron scattering (INS) investigations on these compounds. Our INS study reveals the persistence of spin gaps of 7 and 10 meV in the 10% La-doped T = Ru and Os compounds, respectively. More interestingly our ND study shows a very small ordered moment of 0.18 μB along the b axis in Ce0.9La0.1Ru2Al10 , however a moment of 0.23 μB still along the c axis in Ce0.9La0.1Os2Al10 . This contrasting behavior can be explained by a different degree of hybridization in CeRu2Al10 and CeOs2Al10 , being stronger in the latter than in the former. Muon spin rotation (μ SR ) studies on Ce1 -xLaxRu2Al10 (x =0 , 0.3, 0.5, and 0.7), reveal the presence of coherent frequency oscillations indicating a long-range magnetically ordered ground state for x =0 to 0.5, but an almost temperature independent Kubo-Toyabe response between 45 mK and 4 K for x =0.7 . We compare the results of the present investigations with those reported on the electron and hole doping in Ce T2Al10 .

  2. Photocatalytic Hydroxylation of Benzene by Dioxygen to Phenol with a Cyano-Bridged Complex Containing Fe(II) and Ru(II) Incorporated in Mesoporous Silica-Alumina.

    PubMed

    Aratani, Yusuke; Oyama, Kohei; Suenobu, Tomoyoshi; Yamada, Yusuke; Fukuzumi, Shunichi

    2016-06-20

    Photocatalytic hydroxylation of benzene to phenol was achieved by using O2 as an oxidant as well as an oxygen source with a cyano-bridged polynuclear metal complex containing Fe(II) and Ru(II) incorporated in mesoporous silica-alumina ([Fe(H2O)3]2[Ru(CN)6]@sAl-MCM-41). An apparent turnover number (TON) of phenol production per the monomer unit of [Fe(H2O)3]2[Ru(CN)6] was 41 for 59 h. The cyano-bridged polynuclear metal complex, [Fe(H2O)3]2[Ru(CN)6], exhibited catalytic activity for thermal hydroxylation of benzene by H2O2 in acetonitrile (MeCN), where the apparent TON of phenol production reached 393 for 60 h. The apparent TON increased to 2500 for 114 h by incorporating [Fe(H2O)3]2[Ru(CN)6] in sAl-MCM-41. Additionally, [Fe(H2O)3]2[Ru(CN)6] acts as a water oxidation catalyst by using [Ru(bpy)3](2+) (bpy = 2,2'-bipyridine) and Na2S2O8 as a photosensitizer and a sacrificial electron acceptor as evidenced by (18)O-isotope labeling experiments. Photoirradiation of an O2-saturated MeCN solution containing [Fe(H2O)3]2[Ru(CN)6]@sAl-MCM-41 and scandium ion provided H2O2 formation, where photoexcited [Ru(CN)6](4-) moiety reduces O2 as indicated by laser flash photolysis measurements. Thus, hydroxylation of benzene to phenol using molecular oxygen photocatalyzed by [Fe(H2O)3]2[Ru(CN)6] occurred via a two-step route; (1) molecular oxygen was photocatalytically reduced to peroxide by using water as an electron donor, and then (2) peroxide thus formed is used as an oxidant for hydroxylation of benzene. PMID:27265780

  3. Combinatorial PtSnM (M = Fe, Ni, Ru and Pd) nanoparticle catalyst library toward ethanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Almeida, T. S.; Van Wassen, A. R.; VanDover, R. B.; de Andrade, A. R.; Abruña, H. D.

    2015-06-01

    Electrode arrays containing 91 combinations of Pt-Sn-M (M = Fe, Ni, Pd, and Ru) were prepared by borohydride reduction of aqueous metal salts on carbon paper, and screened by fluorescence assay for activity as ethanol electrooxidation catalysts. Catalysts that showed high activity for this reaction were identified as being Pt(80)Sn(10)Fe(10), Pt(80)Sn(10)Ni(10), Pt(70)Sn(20)Pd(10), and Pt(70)Sn(10)Ru(20) (numbers in parenthesis indicate atomic percent). These were significantly more active than Pt or PtSn catalysts, also present in the electrode arrays. These 4 compositions were synthesized as nanoparticles and characterized physically and electrochemically. X-ray diffraction showed a Pt face-centered cubic (fcc) structure with an average crystallite size of about 2.0 nm for all catalysts. The electrochemical tests for the oxidation of ethanol revealed excellent electrocatalytic activity and single cell (fuel cell) power density for all four catalyst formulations. Fe-containing catalysts exhibited the highest activity (13 A gPt-1) and single-cell performance (50 mW cm-2) followed by Ni- and Pd-containing materials with similar results; electrocatalytic activity around 10 A gPt-1 and power densities of 43 mW cm-2. The lowest performance was observed for the Ru-containing catalyst. However, its single-cell performance (30 mW cm-2) was still comparable to that of the commercial PtSn-Etek electrocatalyst.

  4. First-Principles Study of Effects of Boron on Magnetic Anisotropy in MgO/CoFe(B)/X (X = Ru, Ta) Systems

    NASA Astrophysics Data System (ADS)

    Suzuki, Shugo; Shiota, Masashi; Fukuchi, Yasushi

    2016-09-01

    We study the effects of boron on the magnetic anisotropy in the MgO/CoFe(B)/X (X = Ru, Ta) systems using relativistic first-principles calculations. It is found that the B atoms tend to be rejected from the CoFeB layer into the X underlayer. The system with no B atoms shows perpendicular magnetic anisotropy when the Fe atoms are adjacent to the MgO layer.

  5. Limits on superconductivity-related magnetization in Sr 2RuO 4 and PrOs 4Sb 12 from scanning SQUID microscopy

    SciTech Connect

    Moler, Kathryn

    2010-08-26

    We present scanning SQUID microscopy data on the superconductors Sr{sub 2}RuO{sub 4} (T{sub c} = 1.5 K) and PrOs{sub 4}Sb{sub 12} (T{sub c} = 1.8 K). In both of these materials, superconductivity-related time-reversal symmetry-breaking fields have been observed by muon spin rotation; our aim was to visualize the structure of these fields. However in neither Sr{sub 2}RuO{sub 4} nor PrOs{sub 4}Sb{sub 12} do we observe spontaneous superconductivity-related magnetization. In Sr{sub 2}RuO{sub 4}, many experimental results have been interpreted on the basis of a p{sub x} {+-} ip{sub y} superconducting order parameter. This order parameter is expected to give spontaneous magnetic induction at sample edges and order parameter domain walls. Supposing large domains, our data restrict domain wall and edge fields to no more than {approx}0.1% and {approx}0.2% of the expected magnitude, respectively. Alternatively, if the magnetization is of the expected order, the typical domain size is limited to {approx}30 nm for random domains, or {approx} 500 nm for periodic domains.

  6. Ionization and photofragmentation of Ru{sub 3}(CO){sub 12} and Os{sub 3}(CO){sub 12}

    SciTech Connect

    Schalk, Oliver E-mail: melanie.mucke@physics.uu.se; Josefsson, Ida; Odelius, Michael; Richter, Robert; Prince, Kevin C.; Mucke, Melanie E-mail: melanie.mucke@physics.uu.se

    2015-10-21

    In this paper, we use a combination of photoelectron spectroscopy, mass spectrometry, and density functional theory calculations to get a detailed understanding of valence single and double ionization and the subsequent dissociation processes. This is exemplified on benchmark systems, trimetallo-dodecacarbonyls M{sub 3}(CO){sub 12} with M = Ru, Os, where the energy remaining in the molecule after photoionization can be retrieved by measuring the degree of fragmentation of the molecular ion. The intensity of different mass peaks can thus be directly related to ionization cross sections obtained by photoelectron spectroscopy. We find that the M—CO dissociation energy rises as the number of CO ligands decreases due to dissociation. Moreover, ionization of the CO ligands has a higher cross section than that of the metal center for both single and double ionization. After advanced fragmentation, a CO bond can break and the carbon atom remains bonded to the metal core. In addition, we found that the valence ionization cross sections of M{sub 3}(CO){sub 12} are maximal at about 40 eV photon energy thus showing a more pronounced shape resonance than Ru and Os-complexes with a single metal atom center. Finally, an np → nd giant resonance absorption causes a significant increase of the ionization cross section above 50 eV for Ru{sub 3}(CO){sub 12}.

  7. Simplified method for the determination of Ru, Pd, Re, Os, Ir and Pt in chromitites and other geological materials by isotope dilution ICP-MS and acid digestion.

    PubMed

    Meisel, T; Moser, J; Fellner, N; Wegscheider, W; Schoenberg, R

    2001-03-01

    A method for the determination of low Ru, Pd, Re, Os, Ir and Pt abundances in geological reference materials by isotope dilution inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion in a high pressure asher (HPA-S) is presented. The digestion technique is similar to that using Carius tubes but easier to handle and reaches higher temperatures. Osmium can be determined as OsO4 with ICP-MS directly after digestion through a sparging technique. The remaining elements are preconcentrated by means of anion column chromatography. The resin is digested directly without elution leading to high yields but this causes problems if Zr is present at higher levels in the silicate rich materials. The analytical results for international platinum group element (PGE) reference materials, chromitite CHR-Bkg, basalt TDB-1 and gabbro WGB-1, are presented and compared with literature data, demonstrating the validity of the described method. Although higher in concentration, PGEs determined for reference material WGB-1 were worse than for TDB-1 indicating a more inhomogeneous distribution of the platinum group mineral phases. The low PGE abundance chromitite standard, CHR-Bkg, is likely to be homogeneous for Ru, Re, Os and Ir and is recommended as a reference material for the study of chromitites. Detection limits (3s x total procedure blank) range from 0.012 ng (Re and Os) to 0.77 ng (Pt), which could be further improved by applying higher quality acids. PMID:11284333

  8. First-principles study on the structure, elastic properties, hardness and electronic structure of TMB{sub 4} (TM=Cr, Re, Ru and Os) compounds

    SciTech Connect

    Pan, Y.; Zheng, W.T.; Guan, W.M.; Zhang, K.H.; Fan, X.F.

    2013-11-15

    The structural formation, elastic properties, hardness and electronic structure of TMB{sub 4} (TM=Cr, Re, Ru and Os) compounds are investigated using first-principles approach. The value of C{sub 22} for these compounds is almost two times bigger than the C{sub 11} and C{sub 33}. The intrinsic hardness, shear modulus and Young's modulus are calculated to be in a sequence of CrB{sub 4}>ReB{sub 4}>RuB{sub 4}>OsB{sub 4}, and the Poisson's ratio and B/G ratio of TMB{sub 4} follow the order of CrB{sub 4}RuB{sub 4}<OsB{sub 4}. The intrinsic hardness of CrB{sub 4} and ReB{sub 4} by LDA is bigger than 40 GPa. The high hardness of TMB{sub 4} compounds is derived from the feature of B–B bonds cage and higher C{sub 22} value. The B–B covalent bonds as bonds cage enhances the resistance to shear deformation and improve the hardness. We predict that the TMB{sub 4} compounds with CrB{sub 4}-type are the potential superhard materials. - Graphical abstract: The first-principles calculations show that the intrinsic hardness of CrB{sub 4} and ReB{sub 4} are bigger than 40 GPa, which are the potential superhard materials due to the B–B bonds cage structure. Display Omitted - Highlights: • The intrinsic hardness of CrB{sub 4} and ReB{sub 4} is bigger than 40 GPa. • The hardness of TMB{sub 4} is calculated to be in a sequence of CrB{sub 4}>ReB{sub 4}>RuB{sub 4}>OsB{sub 4}. • The trend of hardness for TMB{sub 4} is consistent with the variation of elastic modulus. • The C{sub 22} value of TMB{sub 4} is bigger than that of C{sub 11} and C{sub 33}. • The high hardness of TMB{sub 4} is originated from the B–B bonds cage.

  9. Exotic magnetism on the quasi-FCC lattices of the d3 double perovskites La2NaB'O6 (B' = Ru, Os)

    NASA Astrophysics Data System (ADS)

    Aczel, Adam

    2015-03-01

    B-site ordered double perovskites with quantum spins S = 1/2 (d1) and S = 1 (d2) on the B' site have attracted a great deal of recent interest, due to the possibility of studying 4d and 5d magnetism combined with magnetic frustration on the face-centered-cubic (FCC) lattice. There has been less focus on d3 systems, as they are generally expected to behave more classically and yield simple, commensurate magnetic ground states. In contrast, we find evidence for long-range and short-range (ξ = 70 Å at 4 K) incommensurate magnetic order on the quasi-FCC lattices of the monoclinic double perovskites La2NaRuO6andLa2NaOsO6 respectively. Incommensurate magnetic order on the FCC lattice has not been predicted by mean field theory, but may arise via a delicate balance of inequivalent nearest neighbor and next nearest neighbor exchange interactions. Furthermore, in the Ru system with long-range order, inelastic neutron scattering reveals a spin gap Δ = 2.75 meV. Magnetic anisotropy is generally minimized in the more familiar octahedrally-coordinated 3d3 systems, so the large gap observed for La2NaRuO6 may result from the significantly enhanced value of spin-orbit coupling in this 4d3 material.

  10. Photochemical Hydrogen Generation Initiated by Oxidative Quenching of the Excited Ru(bpy)3 (2+) * by a Bio-Inspired [2Fe2S] Complex.

    PubMed

    Na, Yong; Wei, Peicheng; Zhou, Li

    2016-07-18

    A diiron dithiolate complex 1 containing 1,8-naphthalic anhydride bridge was prepared, which possessed the lowest reduction potential for the synthetic diiron complexes modeled on the active site of [FeFe] hydrogenase reported so far. For the first time, oxidative quenching of the excited Ru(bpy)3 (2+) * through electron transfer to a bio-inspired [2Fe2S] complex was corroborated. Hydrogen evolution, driven by visible light, was successfully observed for a three-component system, consisting of Ru(bpy)3 (2+) , complex 1, and EDTA as electron donor in aqueous/organic media. These results provide a basis and also opportunity to develop a photo water splitting system employing Fe-based catalysts without sacrificial electron donors. PMID:26879325

  11. Inverse magnetocaloric effect in Ce(Fe{sub 0.96}Ru{sub 0.04}){sub 2}: Effect of fast neutron irradiation

    SciTech Connect

    Dube, V.; Mishra, P. K.; Prajapat, C. L.; Singh, M. R.; Ravikumar, G.; Rajarajan, A. K.; Sastry, P. U.; Thakare, S. V.

    2013-02-05

    We have shown the effect of fast neutron irradiation on the magnetic phase transition and magnetocaloric effect (MCE) in a doped Ce(Fe{sub 0.96}Ru{sub 0.04}){sub 2}, intermettalic. We show that this leads to suppression of MCE and a to a disordered ferromagnetic phase.

  12. Tailoring the composition of ultrathin, ternary alloy PtRuFe nanowires for the methanol oxidation reaction and formic acid oxidation reaction

    SciTech Connect

    Scofield, Megan E.; Koenigsmann, Christopher; Wang, Lei; Liu, Haiqing; Wong, Stanislaus S.

    2014-11-25

    In the search for alternatives to conventional Pt electrocatalysts, we have synthesized ultrathin, ternary PtRuFe nanowires (NW), possessing different chemical compositions in order to probe their CO tolerance as well as electrochemical activity as a function of composition for both (i) the methanol oxidation reaction (MOR) and (ii) the formic acid oxidation reaction (FAOR). As-prepared ‘multifunctional’ ternary NW catalysts exhibited both higher MOR and FAOR activity as compared with binary Pt₇Ru₃ NW, monometallic Pt NW, and commercial catalyst control samples. In terms of synthetic novelty, we utilized a sustainably mild, ambient wet-synthesis method never previously applied to the fabrication of crystalline, pure ternary systems in order to fabricate ultrathin, homogeneous alloy PtRuFe NWs with a range of controlled compositions. Thus, these NWs were subsequently characterized using a suite of techniques including XRD, TEM, SAED, and EDAX in order to verify not only the incorporation of Ru and Fe into the Pt lattice but also their chemical homogeneity, morphology, as well as physical structure and integrity. Lastly, these NWs were electrochemically tested in order to deduce the appropriateness of conventional explanations such as (i) the bi-functional mechanism as well as (ii) the ligand effect to account for our MOR and FAOR reaction data. Specifically, methanol oxidation appears to be predominantly influenced by the Ru content, whereas formic acid oxidation is primarily impacted by the corresponding Fe content within the ternary metal alloy catalyst itself.

  13. Tailoring the composition of ultrathin, ternary alloy PtRuFe nanowires for the methanol oxidation reaction and formic acid oxidation reaction

    DOE PAGESBeta

    Scofield, Megan E.; Koenigsmann, Christopher; Wang, Lei; Liu, Haiqing; Wong, Stanislaus S.

    2014-11-25

    In the search for alternatives to conventional Pt electrocatalysts, we have synthesized ultrathin, ternary PtRuFe nanowires (NW), possessing different chemical compositions in order to probe their CO tolerance as well as electrochemical activity as a function of composition for both (i) the methanol oxidation reaction (MOR) and (ii) the formic acid oxidation reaction (FAOR). As-prepared ‘multifunctional’ ternary NW catalysts exhibited both higher MOR and FAOR activity as compared with binary Pt₇Ru₃ NW, monometallic Pt NW, and commercial catalyst control samples. In terms of synthetic novelty, we utilized a sustainably mild, ambient wet-synthesis method never previously applied to the fabrication ofmore » crystalline, pure ternary systems in order to fabricate ultrathin, homogeneous alloy PtRuFe NWs with a range of controlled compositions. Thus, these NWs were subsequently characterized using a suite of techniques including XRD, TEM, SAED, and EDAX in order to verify not only the incorporation of Ru and Fe into the Pt lattice but also their chemical homogeneity, morphology, as well as physical structure and integrity. Lastly, these NWs were electrochemically tested in order to deduce the appropriateness of conventional explanations such as (i) the bi-functional mechanism as well as (ii) the ligand effect to account for our MOR and FAOR reaction data. Specifically, methanol oxidation appears to be predominantly influenced by the Ru content, whereas formic acid oxidation is primarily impacted by the corresponding Fe content within the ternary metal alloy catalyst itself.« less

  14. Investigation of the binding of cis/trans-[MCl4(1H-indazole)(NO)](-) (M = Ru, Os) complexes to human serum albumin.

    PubMed

    Dömötör, Orsolya; Rathgeb, Anna; Kuhn, Paul-Steffen; Popović-Bijelić, Ana; Bačić, Goran; Enyedy, Eva Anna; Arion, Vladimir B

    2016-06-01

    Overall binding affinity of sodium or indazolium cis/trans-[MCl4(1H-indazole)(NO)] (M = Ru, Os) complexes towards human serum albumin (HSA) and high molecular mass components of the blood serum was monitored by ultrafiltration. HSA was found to be mainly responsible for the binding of the studied ruthenium and osmium complexes. In other words, this protein can provide a depot for the compounds and can affect their biodistribution and transport processes. In order to elucidate the HSA binding sites tryptophan fluorescence quenching studies and displacement reactions with the established site markers warfarin and dansylglycine were performed. Conditional stability constants for the binding to sites I and II on HSA were computed showing that the studied ruthenium and osmium complexes are able to bind into both sites with moderately strong affinity (logK' = 4.4-5.1). Site I is slightly more favored over site II for all complexes. No significant differences in the HSA binding properties were found for these metal complexes demonstrating negligible influence of the type of counterion (sodium vs indazolium), the metal ion center identity (Ru vs. Os) or the position of the nitrosyl group on the binding event. Electron paramagnetic resonance spin labeling of HSA revealed that indazolium trans-[RuCl4(1H-indazole)(NO)] and long-chain fatty acids show competitive binding to HSA. Moreover, this complex has a higher affinity for site I, but when present in excess, it is able to bind to site II as well, and displace fatty acids. PMID:26908285

  15. Synthesis, crystal structure, and electronic properties of high-pressure PdF2-type oxides MO2 (M = Ru, Rh, Os, Ir, Pt).

    PubMed

    Shirako, Yuichi; Wang, Xia; Tsujimoto, Yoshihiro; Tanaka, Kie; Guo, Yanfeng; Matsushita, Yoshitaka; Nemoto, Yoshihiro; Katsuya, Yoshio; Shi, Youguo; Mori, Daisuke; Kojitani, Hiroshi; Yamaura, Kazunari; Inaguma, Yoshiyuki; Akaogi, Masaki

    2014-11-01

    The polycrystalline MO2's (HP-PdF2-type MO2, M = Rh, Os, Pt) with high-pressure PdF2 compounds were successfully synthesized under high-pressure conditions for the first time, to the best of our knowledge. The crystal structures and electromagnetic properties were studied. Previously unreported electronic properties of the polycrystalline HP-PdF2-type RuO2 and IrO2 were also studied. The refined structures clearly indicated that all compounds crystallized into the HP-PdF2-type structure, M(4+)O(2-)2, rather than the pyrite-type structure, M(n+)(O2)(n-) (n < 4). The MO2 compounds (M = Ru, Rh, Os, Ir) exhibited metallic conduction, while PtO2 was highly insulating, probably because of the fully occupied t2g band. Neither superconductivity nor a magnetic transition was detected down to a temperature of 2 K, unlike the case of 3d transition metal chalcogenide pyrites. PMID:25337807

  16. Unanticipated spin gap measured in the frustrated quasi-FCC d3 double perovskites La2 LiXO6 (X = Ru, Os)

    NASA Astrophysics Data System (ADS)

    Maharaj, Dalini D.; Sala, Gabriele; Marjerrison, Casey A.; Greedan, John; Gaulin, Bruce; Stone, Matthew

    There is much current interest in the influence of strong spin-orbit (SO) interactions on exotic ground state selection in new 4d and 5d magnets, particularly involving 4d5 Ir. Here we consider double perovskites of the form A2 BB'O6 which are based on heavy 4d or 5d magnetic ions, where the SO interaction is expected to be significant as it increases as ~Z4 . The double perovskite structure can accommodate a variety of magnetic ions on the B' site, providing a playground for systematic studies of the exotic ground states stabilized by strong SO coupling. Here, we report inelastic neutron scattering (INS) measurements conducted on the frustrated monoclinic magnets, La2LiXO6 (X = Ru, Os), wherein the magnetic moments decorate a quasi face-centered-cubic lattice. Our results show the development of a spin gap in the spin excitation spectrum of size ΔOs = 8 meV and ΔRu = 2.5meV concomitant with TN, which is unexpected for orbitally quenched d3 systems. We liken these results to INS results obtained for Ba2YXO6 and La2NaXO6, which were also shown to exhibit spin gaps that correlate with TN. We shall discuss trends observed in these three d3 double perovskite families which correlate strong SO coupling, spin gap and TN.

  17. Microstructure and ordering parameter studies in multilayer [FePt(x)/Os]{sub n} films

    SciTech Connect

    Chiang, D. P.; Chen, S. Y.; Chen, Y. Y.; Yao, Y. D.; Ouyang, H.; Yu, C. C.; Lin, H. M.

    2011-04-01

    The microstructure, ordering parameter, and magnetic properties of multilayer [FePt(x)/Os]{sub n} films on glass substrate by dc-magnetron sputtering (with x being thickness in nm; Os with a fixed thickness 5 nm; n being the number of layers) have been studied as a function of the annealing temperatures between 300 and 900 deg. C. The grain size of multilayer films can be controlled by annealing temperature and thickness of the FePt layer with Os space layer. The coercivity as a function of the annealing temperature for samples with n = 1 and pure FePt behaves roughly saturated after annealing above 700 deg. C. However, for samples with n > 4 the value of H{sub c} seems still increasing with increasing annealing temperature between 600 and 900 deg. C, and the ordering parameter decreases with increasing the number of Os layers. Our experimental results are reasonably well to describe the effect of strain-assisted transformation.

  18. Noncollinear ferromagnetic easy axes in Py/Ru/FeCo/IrMn spin valves induced by oblique deposition

    SciTech Connect

    Bueno, T. E. P.; Parreiras, D. E.; Gomes, G. F. M.; Krambrock, K.; Paniago, R.; Michea, S.; Rodríguez-Suárez, R. L.; Filho, M. S. Araújo; Macedo, W. A. A.

    2014-06-16

    We present an investigation on the magnetic properties of Py/Ru/FeCo/IrMn spin valves grown by dc magnetron sputtering. The sample fabrication setup has two important features, (i) the five magnetron sputtering sources are placed in a cluster flange 72° from each other, and (ii) each source is tilted with respect to the sample normal. In-plane angular dependence of the ferromagnetic resonance (FMR) was used to obtain the relevant magnetic anisotropies, such as uniaxial and exchange bias fields. The oblique deposition geometry employed has induced non-collinear easy axes of the two ferromagnetic (FM) layers, with high uniaxial field strengths. The symmetry shift of the angular dependence of the FMR resonances of the two FM layers gives us directly the angle between the easy axes of FM{sub 1} (Py) and FM{sub 2} (FeCo), which turned out to be the angle between two adjacent sputtering sources. The observations of the present study suggest that, by combining oblique deposition and appropriate angles of incidence of the deposition flux, the uniaxial (and unidirectional) axes of individual FM layers can be precisely engineered in spin valve fabrication.

  19. Reactivity of Fe sub 3 and Ru sub 3. mu. sub 3 -phenylimido clusters with alkynes, allene, and 1,3-cyclohexadiene

    SciTech Connect

    Song, Jeongsup; Han, Sunghwan; Nguyen, S.T.; Geoffroy, G.L. )

    1990-08-01

    The reactivity of alkynes with the imido clusters Ru{sub 3}({mu}{sub 3}-NPh){sub 2}(CO){sub 9}, H{sub 2}Ru{sub 3}({mu}{sub 3}-NPh)(CO){sub 9}, Fe{sub 3}({mu}{sub 3}-NPh)(CO){sub 10}, Fe{sub 3}({mu}{sub 3}-NPh){sub 2}(CO){sub 9}, and H{sub 2}Fe{sub e}({mu}{sub 3}-NPh)(CO){sub 9} has been examined. The cluster Fe{sub 3}({mu}{sub 3}-NPh)(CO){sub 10} reacts regiospecifically with a series of alkynes to form the binuclear ferrapyrrolinone complexes Fe{sub 2}({mu}{sub 2}-{eta}{sup 3}-RC{double bond}C(R{prime})C(O)NPh)(CO){sub 6}, possessing a metallacycle formed by coupling of the alkyne with CO and the imido ligand. The bis(imido) cluster Ru{sub 3}({mu}{sub 3}-NPh){sub 2}(CO){sub 9} reacts with PhC{triple bond}CPh to form the tetranuclear cluster Ru{sub 4}({mu}{sub 3}-NPh){sub 2}({eta}{sup 2}-{mu}{sub 2}-PhC{triple bond}CPh)(CO){sub 10}, which has been crystallographically shown to possess a butterfly arrangement of the four ruthenium atoms with the alkyne bridging the hinge of the butterfly in a perpendicular fashion and with the imido ligands bridging the open triangular faces of the butterfly.

  20. pH-Dependent isotope exchange and hydrogenation catalysed by water-soluble NiRu complexes as functional models for [NiFe]hydrogenases.

    PubMed

    Kure, Bunsho; Matsumoto, Takahiro; Ichikawa, Koji; Fukuzumi, Shunichi; Higuchi, Yoshiki; Yagi, Tatsuhiko; Ogo, Seiji

    2008-09-21

    The pH-dependent hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes and hydrogenation of the carbonyl compounds have been investigated with water-soluble bis(mu-thiolate)(mu-hydride)NiRu complexes, Ni(II)(mu-SR)(2)(mu-H)Ru(II) {(mu-SR)(2) = N,N'-dimethyl-N,N'-bis(2-mercaptoethyl)-1,3-propanediamine}, as functional models for [NiFe]hydrogenases. In acidic media (at pH 4-6), the mu-H ligand of the Ni(II)(mu-SR)(2)(mu-H)Ru(II) complexes has H(+) properties, and the complexes catalyse the hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes. A mechanism of the hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes through a low-valent Ni(I)(mu-SR)(2)Ru(I) complex is proposed. In contrast, in neutral-basic media (at pH 7-10), the mu-H ligand of the Ni(II)(mu-SR)(2)(mu-H)Ru(II) complexes acts as H(-), and the complexes catalyse the hydrogenation of carbonyl compounds. PMID:18728883

  1. Effect of metal exchange (Os vs. Ru) and co-ligand variation (Cl(-)vs. acac(-)) on the oxidation state distribution in complexes of an o-phenylenediamido(2(-))/o-quinonediimine redox system.

    PubMed

    Chatterjee, Sudipta; Singh, Priti; Fiedler, Jan; Baková, Radka; Zális, Stanislav; Kaim, Wolfgang; Goswami, Sreebrata

    2009-10-01

    The compounds OsCl2L2 (1), RuCl2L2 (2) and Ru(acac)2L (3), Ldegrees = N-phenyl-o-quinonediimine and acac- = 2,4-pentanedionato, have been synthesised and electrochemically, spectroscopically and structurally characterised with the support of detailed DFT calculations. For the new osmium compound 1, the average values for CNH (1.331 A), CNPh (1.345 A) and CC(meta) bond lengths at 1.360 A agree more with an o-semiquinonediimine than with an o-quinonediimine formulation for the coordinated ligand, whereas the latter assignment is more appropriate to describe the ruthenium analogue 2 (average bond lengths of 1.308, 1.324 and 1.348 A, respectively). In turn, the corresponding average bond lengths in 3 (1.333, 1.352 and 1.350 A, respectively) are suggestive of an o-semiquinonediimine ligand. DFT calculations confirm the structural data and describe the electronic structures related to the oxidation state assignments. The stabilisation of trivalent ruthenium by electron donating acac- in 3 = RuIII(acac)2(L*-) and the preference of osmium for higher oxidation states (here: OsIVCl2(L*-)2 in 1) as compared to ruthenium analogues (here: RuIICl2(Ldegrees)2 in 2) in otherwise similar setting is responsible for these results. Oxidation of the diamagnetic complexes proceeds to partly EPR and UV-VIS spectroelectrochemically detectable cations with metal-centered spin, suggesting the following formulations: [OsIIICl2(Ldegrees)2]+ for 1+, [RuIIICl2(Ldegrees)2]+ for labile 2+, and [RuIII(acac)2(Ldegrees)]+ for 3+. In the case of 3, reversible metal-centered reduction results in ligand-based spin as compatible with a [RuII(acac)2(L*-)]- situation for 3-. PMID:19759953

  2. Magnetoelectric Coupling in Well-Ordered Epitaxial BiFeO3/CoFe2O4/SrRuO3 Heterostructured Nanodot Array.

    PubMed

    Tian, Guo; Zhang, Fengyuan; Yao, Junxiang; Fan, Hua; Li, Peilian; Li, Zhongwen; Song, Xiao; Zhang, Xiaoyan; Qin, Minghui; Zeng, Min; Zhang, Zhang; Yao, Jianjun; Gao, Xingsen; Liu, Junming

    2016-01-26

    Multiferroic magnetoelectric (ME) composites exhibit sizable ME coupling at room temperature, promising applications in a wide range of novel devices. For high density integrated devices, it is indispensable to achieve a well-ordered nanostructured array with reasonable ME coupling. For this purpose, we explored the well-ordered array of isolated epitaxial BiFeO3/CoFe2O4/SrRuO3 heterostructured nanodots fabricated by nanoporous anodic alumina (AAO) template method. The arrayed heterostructured nanodots demonstrate well-established epitaxial structures and coexistence of piezoelectric and ferromagnetic properties, as revealed by transmission electron microscopy (TEM) and peizoeresponse/magnetic force microscopy (PFM/MFM). It was found that the heterostructured nanodots yield apparent ME coupling, likely due to the effective transfer of interface couplings along with the substantial release of substrate clamping. A noticeable change in piezoelectric response of the nanodots can be triggered by magnetic field, indicating a substantial enhancement of ME coupling. Moreover, an electric field induced magnetization switching in these nanodots can be observed, showing a large reverse ME effect. These results offer good opportunities of the nanodots for applications in high-density ME devices, e.g., high density recording (>100 Gbit/in.(2)) or logic devices. PMID:26651132

  3. Properties of KCo2As2 and alloys with Fe and Ru: density functional calculations

    SciTech Connect

    Singh, David J

    2009-01-01

    Electronic-structure calculations are presented for KCo{sub 2}As{sub 2} and alloys with KFe{sub 2}As{sub 2} and KRu{sub 2}As{sub 2}. These materials show electronic structures characteristic of coherent alloys with a similar Fermi surface structure to that of the Fe-based superconductors when the d-electron count is near 6 per transition metal. However, they are less magnetic than the corresponding Fe compounds. These results are discussed in relation to superconductivity.

  4. Intrinsic defect-mediated conduction and resistive switching in multiferroic BiFeO3 thin films epitaxially grown on SrRuO3 bottom electrodes

    NASA Astrophysics Data System (ADS)

    Lee, Ji Hye; Jeon, Ji Hoon; Yoon, Chansoo; Lee, Sangik; Kim, Yeon Soo; Oh, Tae Joon; Kim, Young Heon; Park, Jinsu; Song, Tae Kwon; Park, Bae Ho

    2016-03-01

    We report the impact of intrinsic defects in epitaxial BiFeO3 films on charge conduction and resistive switching of Pt/BiFeO3/SrRuO3 capacitors, although the BiFeO3 films show very similar ferroelectric domain types probed by piezoresponse force microscopy. Capacitors with p-type Bi-deficient and n-type Bi-rich BiFeO3 films exhibit switchable diode and conventional bipolar resistive switching behaviors, respectively. Both the capacitors show good retention properties with a high ON/OFF ratio of >100 in Bi-deficient films and that of >1000 in Bi-rich films. The present investigation advances considerably understanding of interface control through defect engineering of BiFeO3 thin films for non-volatile memory application.

  5. Transport properties, upper critical field and anisotropy of Ba(Fe0.75Ru0.25)2As2 single crystals

    NASA Astrophysics Data System (ADS)

    Xing, Jie; Shen, Bing; Zeng, Bin; Liu, JianZhong; Ding, XiaXin; Wang, ZhiHe; Yang, Huan; Wen, HaiHu

    2012-12-01

    The temperature and angle dependent resistivity of Ba(Fe0.75Ru0.25)2As2 single crystals were measured in magnetic fields up to 14 T. The temperature dependent resistivity with the magnetic field aligned parallel to c-axis and ab-planes allow us to derive the slope of d H {/c2 ab }/d T and d H {/c2 c }/d T near T c yielding an anisotropy ratio Γ = d H {/c2 ab }/d T/d H {/c2 c }/d T≈2. By scaling the curves of resistivity vs. angle measured at a fixed temperature but different magnetic fields within the framework of the anisotropic Ginzburg-Landau theory, we obtained the anisotropy in an alternative way. Again we found that the anisotropy ( m c / m ab )1/2 was close to 2. This value is similar to that in Ba0.6K0.4Fe2As2 (K-doped Ba122) and Ba(Fe0.92Co0.08)2As2 (Co-doped Ba122). This suggests that the 3D warping effect of the Fermi surface in Ru-doped samples may not be stronger than that in the K-doped or Co-doped Ba122 samples, therefore the possible nodes appearing in Ru-doped samples cannot be ascribed to the 3D warping effect of the Fermi surface.

  6. Investigation of magnetic order in SmTr2Zn20 (Tr = Fe, Co, Ru) and SmTr2Cd20 (Tr = Ni, Pd)

    NASA Astrophysics Data System (ADS)

    Yazici, Duygu; White, B. D.; Ho, P.-C.; Kanchanavatee, N.; Huang, K.; Dilley, N. R.; Maple, M. B.

    2015-03-01

    Single crystals of the cage compounds Sm Tr 2Zn20 (Tr = Fe, Co, Ru) and Sm Tr 2Cd20 (Tr = Ni, Pd) have been investigated by means of electrical resistivity, magnetization, and specific heat measurements. The compounds SmFe2Zn20, SmRu2Zn20,andSmNi2Cd20 exhibit ferromagnetic order with Curie temperatures of TC = 47.4 K, 7.6 K, and 7.5 K, respectively, whereas SmPd2Cd20 is an antiferromagnet with a Néel temperature of TN = 3.4 K. No evidence for magnetic order is observed in SmCo2Zn20 down to 110 mK. The Sommerfeld coefficients γ are found to be 57 mJ/mol-K2 for SmFe2Zn20, 79.5 mJ/mol-K2 for SmCo2Zn20, 258 mJ/mol-K2 for SmRu2Zn20, 165 mJ/mol-K2 for SmNi2Cd20, and 208 mJ/mol-K2 for SmPd2Cd20. Enhanced values of Sommerfeld coefficients γ and a quadratic temperature dependence of the electrical resistivity at low temperature for SmRu2Zn20andSmPd2Cd20 suggest an enhancement of the quasiparticle masses due to hybridization between localized 4 f and conduction electron states. Research at UCSD was supported by the U.S. DOE under Grant No. DE-FG02-04-ER46105 and the U.S. NSF under Award Grant No. DMR 1206553. Research at California State University, Fresno was supported by the U.S. NSF under Grant No. DMR 1104544.

  7. Direct observation of an anisotropic in-plane residual stress induced by B addition as an origin of high magnetic anisotropy field of Ru/FeCoB film

    NASA Astrophysics Data System (ADS)

    Hirata, Ken-ichiro; Gomi, Shunsuke; Mashiko, Yasuhiro; Nakagawa, Shigeki

    2010-05-01

    Although boron-free FeCo films prepared on a Ru underlayer exhibits isotropic in-plane magnetic property, boron added FeCoB films prepared on Ru underlayer revealed large in-plane magnetic anisotropy with a high anisotropy field of 500 Oe. The effect of boron addition on the in-plane anisotropic residual stress in FeCoB film was investigated using sin2 ψ method of x-ray diffraction analysis. Large isotropic compressive stress was observed in Ru/FeCo film. In contrast, anisotropic in-plane residual stress was observed in Ru/FeCoB film. The compressive stress along the easy axis of Ru/FeCoB film is released more than that along the hard axis. Such anisotropic residual stress is regarded as an origin of the in-plane magnetic anisotropy through inverse magnetostriction effect. Owing to the configuration of the facing targets sputtering system, boron atoms are sputtered and deposited anisotropically, and so they penetrate FeCo crystals and release the compressive stress along the incidence direction.

  8. Direct observation of an anisotropic in-plane residual stress induced by B addition as an origin of high magnetic anisotropy field of Ru/FeCoB film

    SciTech Connect

    Hirata, Ken-ichiro; Gomi, Shunsuke; Mashiko, Yasuhiro; Nakagawa, Shigeki

    2010-05-15

    Although boron-free FeCo films prepared on a Ru underlayer exhibits isotropic in-plane magnetic property, boron added FeCoB films prepared on Ru underlayer revealed large in-plane magnetic anisotropy with a high anisotropy field of 500 Oe. The effect of boron addition on the in-plane anisotropic residual stress in FeCoB film was investigated using sin{sup 2} {psi} method of x-ray diffraction analysis. Large isotropic compressive stress was observed in Ru/FeCo film. In contrast, anisotropic in-plane residual stress was observed in Ru/FeCoB film. The compressive stress along the easy axis of Ru/FeCoB film is released more than that along the hard axis. Such anisotropic residual stress is regarded as an origin of the in-plane magnetic anisotropy through inverse magnetostriction effect. Owing to the configuration of the facing targets sputtering system, boron atoms are sputtered and deposited anisotropically, and so they penetrate FeCo crystals and release the compressive stress along the incidence direction.

  9. RuO2 nanoparticle-modified (Ce,Mn,Fe)O2/(La,Sr) (Fe,Mn)O3 composite oxide as an active anode for direct hydrocarbon type solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Shin, Tae Ho; Hagiwara, Hidehisa; Ida, Shintaro; Ishihara, Tatsumi

    2015-09-01

    Composite oxide anodes have recently attracted great attention as alternative materials for solid oxide fuel cell anodes because of their potential to overcome the serious performance deterioration associated with the traditional Ni-based cermet. In particular, oxide anodes show a greater tolerance to coke and reoxidation than existing Ni-based cermets. In this study, the anodic performance of a (Ce,Mn,Fe)O2/(La,Sr) (Fe,Mn)O3 composite oxide modified with additional amounts of catalytically active RuO2 nanoparticles was investigated. Heat treatment resulted in highly dispersed RuO2 particles (ca. 10 nm). Anodes containing 10 wt% added RuO2 exhibited fairly high maximum power densities of 0.3 and 1.5 W cm-2 in H2 and C3H8, respectively, at 800 °C. The cells showed stable power density and negligible carbon formation even after 50 h of operation at 1 A cm-2. The increased power density was assigned to decreased anodic overpotential and internal resistance losses because RuO2 nanoparticles contribute to the increase in electrical conductivity.

  10. Lattice instability and competing spin structures in the double perovskite insulator Sr2FeOsO6.

    PubMed

    Paul, Avijit Kumar; Reehuis, Manfred; Ksenofontov, Vadim; Yan, Binghai; Hoser, Andreas; Többens, Daniel M; Abdala, Paula M; Adler, Peter; Jansen, Martin; Felser, Claudia

    2013-10-18

    The semiconductor Sr2FeOsO6, depending on temperature, adopts two types of spin structures that differ in the spin sequence of ferrimagnetic iron-osmium layers along the tetragonal c axis. Neutron powder diffraction experiments, 57Fe Mössbauer spectra, and density functional theory calculations suggest that this behavior arises because a lattice instability resulting in alternating iron-osmium distances fine-tunes the balance of competing exchange interactions. Thus, Sr2FeOsO6 is an example of a double perovskite, in which the electronic phases are controlled by the interplay of spin, orbital, and lattice degrees of freedom. PMID:24182298

  11. Prediction of elastic and vibrational stability for Sc, Ti, Y, Zr, Tc, Ru, Hf, Re, and Os in the fcc structure

    NASA Astrophysics Data System (ADS)

    de Coss, Romeo; Cifuentes-Quintal, Eduardo; Aguayo, Aaron; Murrieta, Gabriel

    2014-03-01

    The discovery of a metastable phase for a given material is interesting because corresponds to a new bonding and new properties are expected. The calculation of the total-energy along the Bain path is frequently used as a method to find tetragonal metastable states. However, a local minimum in the tetragonal distortion is not a definitive proof of a metastable state, and the elastic and vibrational stability needs to be evaluated. In a previous work, using the elastic stability criteria for a cubic structure, we have shown that the transition metals with hcp ground state; Ti, Zr, and Hf have a fcc metastable phase. That result is interesting since the fcc crystal structure does not appear in the current pressure-temperature phase diagram of these metals, and support the experimental observations of fcc Ti and Zr in thin films. In the present work, we extend the stability study of the fcc structure to the non-magnetic transition metals with hcp ground state; Sc, Ti, Y, Zr, Tc, Ru, Hf, Re, and Os. We find that all the metals involved in this study have a metastable fcc structure, since the phonon band structure shows only positive frequencies. Finally, substrates on which the fcc structure of these metals could be growth epitaxially are predicted.

  12. Materials discovery by crystal growth: Lanthanide metal containing oxides of the platinum group metals (Ru, Os, Ir, Rh, Pd, Pt) from molten alkali metal hydroxides

    SciTech Connect

    Mugavero, Samuel J.; Gemmill, William R.; Roof, Irina P.; Loye, Hans-Conrad zur

    2009-07-15

    This review addresses the process of materials discovery via crystal growth, specifically of lanthanide metal containing oxides of the platinum group metals (Ru, Os, Ir, Rh, Pd, Pt). It provides a detailed overview of the use of hydroxide fluxes for crystal growth. The melt chemistry of hydroxide fluxes, specifically, the extensive acid base chemistry, the metal cation solubility, and the ability of hydroxide melts to oxidize metals are described. Furthermore, a general methodology for the successful crystal growth of oxides is provided, including a discussion of experimental considerations, suitable reaction vessels, reaction profiles and temperature ranges. Finally, a compilation of complex platinum group metal oxides recently synthesized using hydroxide melts, focusing on their crystal growth and crystal structures, is included. - Graphical abstract: A review that addresses the process of materials discovery via crystal growth using hydroxide fluxes. It provides a detailed overview of the use of hydroxide fluxes for crystal growth and describes the melt chemistry of hydroxide fluxes, specifically, the extensive acid base chemistry, the metal cation solubility, and the ability of hydroxide melts to oxidize metals. In addition, a compilation of complex platinum group metal oxides recently synthesized using hydroxide melts is included.

  13. Spin-glass behavior and pyroelectric anomalies in a new lithium-based oxide, Li3FeRuO5.

    PubMed

    Upadhyay, Sanjay Kumar; Paulose, P L; Iyer, Kartik K; Sampathkumaran, E V

    2016-08-17

    The results of dc and ac magnetization, heat capacity, (57)Fe Mössbauer spectroscopy, dielectric, pyroelectric current and isothermal magneto-capacitance measurements of a recently reported lithium-rich layered oxide, Li3FeRuO5, related to LiCoO2-type (rhombohedral, space group R3[combining macron]m), are presented. The results reveal that the compound undergoes spin-glass freezing at 15 K. There is a peak around 34 K in pyroelectric data, which cannot be attributed to ferroelectricity, but to the phenomenon of thermally stimulated depolarization current. As revealed by magnetocapacitance data above and below the magnetic ordering temperature, magnetic and electric dipoles appear to be coupled, thereby offering evidence for magnetodielectric coupling. PMID:27498689

  14. Room-temperature polarization switching and antiferromagnetic coupling in epitaxial (Ga,Fe){sub 2}O{sub 3}/SrRuO{sub 3} heterostructures

    SciTech Connect

    Oh, Seol Hee; Lee, Ji Hye; Shin, Ran Hee; Jo, William; Shin, Yooleemi; Meny, Christian

    2015-04-06

    Room-temperature reversible remnant polarization of gallium ferrite thin-films is reported as a multiferroic material with non-zero order parameters of polarization and magnetization. With the addition of Fe ions in Ga sites, Ga{sub 0.6}Fe{sub 1.4}O{sub 3} (GFO) thin films have been considered as potentially promising of multiferroicity. The b-axis oriented epitaxial GFO films were grown on SrRuO{sub 3}(111)/SrTiO{sub 3}(111). The six-fold symmetric in-plane epitaxy of the GFO films was confirmed using X-ray diffraction. The magnetic moment of the films was measured as a function of temperature and external magnetic field, which shows a room-temperature non-zero magnetization. Macroscopic and microscopic methods have been applied to demonstrate the polarization switching of the films. The remnant polarization is measured as 0.05 μC/cm{sup 2}. Reduction of leaky behaviors of the GFO films owing to the conducting oxide of SrRuO{sub 3} will pave a way to take advantage of the room-temperature non-zero multi-orders for future non-volatile memory device applications.

  15. Highly textured Sr, Nb co-doped BiFeO{sub 3} thin films grown on SrRuO{sub 3}/Si substrates by rf- sputtering

    SciTech Connect

    Ostos, C.; Raymond, O.; Siqueiros, J. M.; Suarez-Almodovar, N.; Bueno-Baques, D.; Mestres, L.

    2011-07-15

    In this study, (011)-highly oriented Sr, Nb co-doped BiFeO{sub 3} (BFO) thin films were successfully grown on SrRuO{sub 3}/Si substrates by rf-magnetron sputtering. The presence of parasite magnetic phases was ruled out based on the high resolution x-ray diffraction data. BFO films exhibited a columnar-like grain growth with rms surface roughness values of {approx_equal}5.3 nm and average grain sizes of {approx_equal}65-70 nm for samples with different thicknesses. Remanent polarization values (2P{sub r}) of 54 {mu}C cm{sup -2} at room temperature were found for the BFO films with a ferroelectric behavior characteristic of an asymmetric device structure. Analysis of the leakage mechanisms for this structure in negative bias suggests Schottky injection and a dominant Poole-Frenkel trap-limited conduction at room temperature. Oxygen vacancies and Fe{sup 3+}/Fe{sup 2+} trap centers are consistent with the surface chemical bonding states analysis from x-ray photoelectron spectroscopy data. The (011)-BFO/SrRuO{sub 3}/Si film structure exhibits a strong magnetic interaction at the interface between the multiferroic film and the substrate layer where an enhanced ferromagnetic response at 5 K was observed. Zero-field cooled (ZFC) and field cooled (FC) magnetization curves of this film system revealed a possible spin glass behavior at spin freezing temperatures below 30 K depending on the BFO film thickness.

  16. Re-Os in FeNi, Sulfide, and Phosphide: The Possible Determination of Internal Isochrons for Iron Meteorites

    NASA Astrophysics Data System (ADS)

    Papanastassiou, D. A.; Shen, J. J.; Wasserburg, G. J.

    1995-09-01

    For age determinations of specific events in the evolution of iron meteorites it is essential to obtain a reasonable range of physical-chemical fractionation of Re/Os. The possible stages of iron meteorite evolution which can, in principle, result in Re-Os fractionation include: a) condensation of PGE and of FeNi in the solar nebula; b) subsequent oxidation of part of the Fe by reaction with S; c) segregation and partial removal of massive FeS during melting on parent planetesimals; d) melting followed by fractional crystallization of the metal phase and crystallization of the remaining FeS; e) element redistribution during subsolidus phase transformations to produce schreibersite sheaves and finally precipitation or exsolution of minor micro-phases, e.g., rhabdite, at a later stage. Using negative ion, thermal ionization, we have determined the Re and Os concentrations and Os isotopic compositions in metal samples of iron meteorites. We have also analyzed metal-FeS pairs from two IA iron meteorites and a metal-phosphide pair from one IIIA iron. The analytical results for the paired analyses are shown in Table 1. The Re, Os partition coefficients between these coexisting phases are shown in Table 2. The whole-rock, metal samples for group IA, IIA, IIIA, IVA and IVB irons are consistent with a single, well-defined best fit line which yields a slope of 0.07863+/-0.00031 (corresponding to an age of 4.62+/-0.02 AE;lambda=1.64x10^(-11) a^(-1)) and an initial ^(187)Os/^(188)Os = 0.09560+/-0.00018 (all uncertainties are 2 sigma). There is also a suggestion from the data for the IIA and IVA groups of a difference in ages of 60+/-45 m.y. We find that, in the presence of the metal phase, neither Re nor Os enter into the sulphide. Therefore, the production or segregation of sulphide [e.g., under steps (b) and (c), above] act only as diluents for the Re and Os concentrations and can have no influence on the Re-Os isotope systematics and age determinations. Given the refractory

  17. Strain-mediated electric-field control of exchange bias in a Co90Fe10/BiFeO3/SrRuO3/PMN-PT heterostructure.

    PubMed

    Wu, S Z; Miao, J; Xu, X G; Yan, W; Reeve, R; Zhang, X H; Jiang, Y

    2015-01-01

    The electric-field (E-field) controlled exchange bias (EB) in a Co90Fe10/BiFeO3 (BFO)/SrRuO3/PMN-PT heterostructure has been investigated under different tensile strain states. The in-plane tensile strain of the BFO film is changed from +0.52% to +0.43% as a result of external E-field applied to the PMN-PT substrate. An obvious change of EB by the control of non-volatile strain has been observed. A magnetization reversal driven by E-field has been observed in the absence of magnetic field. Our results indicate that a reversible non-volatile E-field control of a ferromagnetic layer through strain modulated multiferroic BFO could be achieved at room temperature. PMID:25752272

  18. Strain-mediated electric-field control of exchange bias in a Co90Fe10/BiFeO3/SrRuO3/PMN-PT heterostructure

    NASA Astrophysics Data System (ADS)

    Wu, S. Z.; Miao, J.; Xu, X. G.; Yan, W.; Reeve, R.; Zhang, X. H.; Jiang, Y.

    2015-03-01

    The electric-field (E-field) controlled exchange bias (EB) in a Co90Fe10/BiFeO3 (BFO)/SrRuO3/PMN-PT heterostructure has been investigated under different tensile strain states. The in-plane tensile strain of the BFO film is changed from +0.52% to +0.43% as a result of external E-field applied to the PMN-PT substrate. An obvious change of EB by the control of non-volatile strain has been observed. A magnetization reversal driven by E-field has been observed in the absence of magnetic field. Our results indicate that a reversible non-volatile E-field control of a ferromagnetic layer through strain modulated multiferroic BFO could be achieved at room temperature.

  19. Strain-mediated electric-field control of exchange bias in a Co90Fe10/BiFeO3/SrRuO3/PMN-PT heterostructure

    PubMed Central

    Wu, S. Z.; Miao, J.; Xu, X. G.; Yan, W.; Reeve, R.; Zhang, X. H.; Jiang, Y.

    2015-01-01

    The electric-field (E-field) controlled exchange bias (EB) in a Co90Fe10/BiFeO3 (BFO)/SrRuO3/PMN-PT heterostructure has been investigated under different tensile strain states. The in-plane tensile strain of the BFO film is changed from +0.52% to +0.43% as a result of external E-field applied to the PMN-PT substrate. An obvious change of EB by the control of non-volatile strain has been observed. A magnetization reversal driven by E-field has been observed in the absence of magnetic field. Our results indicate that a reversible non-volatile E-field control of a ferromagnetic layer through strain modulated multiferroic BFO could be achieved at room temperature. PMID:25752272

  20. Evolution of the interfacial magnetic anisotropy in MgO/CoFeB/Ta/Ru based multilayers as a function of annealing temperature

    NASA Astrophysics Data System (ADS)

    Aleksandrov, Yuriy; Fowley, Ciarán; Kowalska, Ewa; Sluka, Volker; Yıldırım, Oǧuz; Lindner, Jürgen; Ocker, Berthold; Fassbender, Jürgen; Deac, Alina M.

    2016-06-01

    We report the effect of annealing temperature on the dynamic and static magnetic properties of MgO/CoFeB/Ta/Ru multilayers. Angular resolved ferromagnetic resonance measurement results show that the as-deposited film exhibits in-plane magnetic anisotropy, whereas in the annealed films the magnetic easy-axis is almost along the direction perpendicular to the plane of the layers. The extracted interfacial anisotropy energy, Ki, is maximized at an annealing temperature 225∘C, in agreement with the vibrating sample magnetometry results. Although the magnetization is not fully out-of-plane, controlling the degree of the magnetization obliqueness may be advantageous for specific applications such as spin-transfer oscillators.

  1. Effects of pressure and composition on Pt-Re-Os partitioning behavior between solid and liquid metal in the Fe-Ni-S system: Implication for Os isotopic anomalies in plume-derived lavas

    NASA Astrophysics Data System (ADS)

    Hayashi, H.; Ohtani, E.; Terasaki, H.; Ito, Y.

    2008-12-01

    Coupled 186Os/188Os and 187Os/188Os enrichments of plume-derived lavas have been suggested to reflect material contribution from the outer core (e.g., Brandon, 1998). This geochemical hypothesis is based on an assumption that the outer core shows coupled enrichments in 186Os/ 188Os and 187Os/ 188Os ratio, reflecting the decay of 190Pt and 187Re to 186Os and 187Os, respectively. In order to examine this hypothesis, partitioning experiments of Pt-Re-Os between solid metal and liquid metal were performed using an MA-8 Kawai-type multi-anvil apparatus at 5-20 GPa and 1250-1400C. Starting materials of Fe metal, Ni (7 wt.%) metal and FeS (5 wt.% S in the bulk) were doped with 3 wt.% of Pt, Re and Os metals. Concentrations of all elements were determined using JXA-8800M electron probe microanalyzer with wave-dispersive spectrometry. Measured partition coefficients of Pt, Re and Os increase with increasing sulfur content and almost constant with increasing pressure. Therefore, the effect of liquid composition on the partitioning behavior of highly siderophile elements is much more significant compared to the effect of pressure and temperature. On the basis of the present experimental results, it is unlikely to generate the required Pt-Re-Os fractionation during inner core crystallization assuming that the light element in the Earth"fs core is sulfur only.

  2. Magnetic domains and magnetization reversal of ion-induced magnetically patterned Ruderman-Kittel-Kasuya-Yoshida-coupled Ni{sub 81}Fe{sub 19}/Ru/Co{sub 90}Fe{sub 10} films

    SciTech Connect

    Fassbender, J.; Bischoff, L.; Mattheis, R.; Fischer, P.

    2006-04-15

    Pure magnetic patterning by means of ion-beam irradiation of magnetic thin films and multilayers often results from a postdeposition local modification of the interface structure with only minor effects on the film topography. In the study presented here a 60 keV fine-focused Co ion beam was used to change the coupling in a Ni{sub 81}Fe{sub 19}/Ru/Co{sub 90}Fe{sub 10} structure from antiferromagnetic to ferromagnetic on a micron scale. Thereby an artificial structure with locally varying interlayer exchange coupling and therefore magnetization alignment is produced. High-resolution full-field x-ray microscopy is used to determine the magnetic domain configuration during the magnetization reversal process locally and layer resolved due to the element-specific contrast in circular x-ray dichroism. In the magnetically patterned structure there is, in addition to the locally varying interlayer exchange coupling across the Ru layer, also the direct exchange coupling within each ferromagnetic layer present. Therefore the magnetization reversal behavior of the irradiated stripes is largely influenced by the surrounding magnetic film.

  3. Spin-State Energetics of Fe(III) and Ru(III) Aqua Complexes: Accurate ab Initio Calculations and Evidence for Huge Solvation Effects.

    PubMed

    Radoń, Mariusz; Gąssowska, Katarzyna; Szklarzewicz, Janusz; Broclawik, Ewa

    2016-04-12

    Aqua complexes of transition metals are useful models for understanding the electronic structure of metal-oxide species relevant in photocatalytic water splitting. Moreover, spin-forbidden d-d transitions of aqua complexes provide valuable experimental data of spin-state energetics, which can be used for benchmarking of computational methods. Here, low-energy spin states of Fe(III) and Ru(III) aqua complexes are studied with an array of DFT and high-level wave function methods (CASPT2, RASPT2, NEVPT2, CCSD(T)-F12, and other coupled cluster methods up to full CCSDT). The results from single-reference and multireference methods are cross-checked, and the amount of multireference character for both considered spin states of [Fe(H2O)6](3+) is carefully analyzed. In addition to small [M(H2O)6](3+) clusters (M = Fe, Ru), we also employ larger models [M(H2O)6·(H2O)12](3+), with explicit water molecules in the second coordination sphere, to describe the situation in aqueous solution. By comparing the results for both types of models, our calculations evidence large and systematic solvation effects on the spin-state energetics. It is found that, due to the interaction with hydrogen-bonded water molecules in the second coordination sphere, the first coordination sphere undergoes a noticeable contraction and deformation. In consequence, the presence of solvation shell affects the relative energies of spin states by as much as 3-4 × 10(3) cm(-1) (∼10 kcal/mol). Once this solvation effect is accounted for, the spin-state energetics from CCSD(T) and NEVPT2 calculations turn out to be in an excellent agreement with the experimental estimates, which was not the case for isolated [M(H2O)6](3+) species is gas phase. We thus postulate that significant discrepancies between theory and experimental data for [Fe(H2O)6](3+) that were previously reported in the literature may be plausibly resolved and attributed to the neglect of explicit solvation effects and also, to some extent, to

  4. Demonstration of magnetoelectric memory cell in (110) [Pb(Mg1/2Nb2/3)O3]0.68-[PbTiO3]0.32/Ru/FeCo heterostructures

    NASA Astrophysics Data System (ADS)

    Han, Xuemeng; Xi, Li; Li, Yue; Guo, Xiaobin; Li, Dong; Wang, Zhen; Zuo, Yalu; Xue, Desheng

    2014-09-01

    An electric-field pulses driven magnetoelectric memory cell in a single layered ferromagnetic thin film was fabricated by direct-current magnetron sputtering Ru/Fe65Co35 on ferroelectric (110) [Pb(Mg1/2 Nb2/3)O3]0.68-[PbTiO3]0.32 (PMN-PT) substrates. The magnetization in the orthogonal directions can be reset by the positive/negative electric fields pulse in PMN-PT/Ru/FeCo heterostructures due to the strain mediated converse magnetoelectric effect. The high (low) resistance state was realized under the negative (positive) electric fields pulse due to the anisotropy magnetoresistance of FeCo films. Then, a non-volatile magnetic memory cell with resistance and electric field, respectively, as the media and writing field was realized.

  5. Heavy-impurity resonance, hybridization, and phonon spectral functions in Fe1-xMxSi, M=Ir,Os

    DOE PAGESBeta

    Delaire, O.; Al-Qasir, Iyad I.; May, Andrew F.; Sales, Brian C.; Niedziela, Jennifer L.; Ma, Jie; Matsuda, Masaaki; Abernathy, Douglas L.; Berlijn, Tom

    2015-03-31

    The vibrational behavior of heavy substitutional impurities (M=Ir,Os) in Fe1-xMxSi (x = 0, 0.02, 0.04, 0.1) was investigated with a combination of inelastic neutron scattering (INS), transport measurements, and first-principles simulations. In this paper, our INS measurements on single-crystals mapped the four-dimensional dynamical structure factor, S(Q;E), for several compositions and temperatures. Our results show that both Ir and Os impurities lead to the formation of a weakly dispersive resonance vibrational mode, in the energy range of the acoustic phonon dispersions of the FeSi host. We also show that Ir doping, which introduces free carriers and increases electron-phonon coupling, leads tomore » softened interatomic force-constants compared to doping with Os, which is isoelectronic to Fe. We analyze the phonon S(Q,E) from INS through a Green's function model incorporating the phonon self-energy based on first-principles density functional theory (DFT) simulations. Calculations of the quasiparticle spectral functions in the doped system reveal the hybridization between the resonance and the acoustic phonon modes. Finally, our results demonstrate a strong interaction of the host acoustic dispersions with the resonance mode, likely leading to the large observed suppression in lattice thermal conductivity.« less

  6. Heavy-impurity resonance, hybridization, and phonon spectral functions in Fe 1 x M x Si (M= Ir, Os)

    DOE PAGESBeta

    Delaire, O.; Al-Qasir, Iyad I.; May, Andrew F.; Sales, Brian C.; Niedziela, Jennifer L.; Ma, Jie; Matsuda, Masaaki; Abernathy, Douglas L.; Berlijn, Tom

    2015-03-31

    The vibrational behavior of heavy substitutional impurities (M=Ir,Os) in Fe1􀀀xMxSi (x = 0; 0:02; 0:04; 0:1) was investigated with a combination of inelastic neutron scattering (INS), transport measurements, and rst-principles simulations. Our INS measurements on single-crystals mapped the four-dimensional dynamical structure factor, S(Q;E), for several compositions and temperatures. Our results show that both Ir and Os impurities lead to the formation of a weakly dispersive resonance vibrational mode, in the energy range of the acoustic phonon dispersions of the FeSi host. We also show that Ir doping, which introduces free carriers and increases electron-phonon coupling, leads to softened interatomic force-constantsmore » compared to doping with Os, which is isoelectronic to Fe. We analyze the phonon S(Q;E) from INS through a Green's function model incorporating the phonon self-energy based on rst-principles density functional theory (DFT) simulations. Calculations of the quasiparticle spectral functions in the doped system reveal the hybridization between the resonance and the acoustic phonon modes. Our results demonstrate a strong interaction of the host acoustic dispersions with the resonance mode, likely leading to the large observed suppression in lattice thermal conductivity.« less

  7. Heavy-impurity resonance, hybridization, and phonon spectral functions in Fe1-xMxSi (M =Ir , Os )

    NASA Astrophysics Data System (ADS)

    Delaire, O.; Al-Qasir, I. I.; May, A. F.; Li, C. W.; Sales, B. C.; Niedziela, J. L.; Ma, J.; Matsuda, M.; Abernathy, D. L.; Berlijn, T.

    2015-03-01

    The vibrational behavior of heavy substitutional impurities (M = Ir,Os) in Fe1-xMxSi (x =0 ,0.02 ,0.04 ,0.1 ) was investigated with a combination of inelastic neutron scattering (INS), transport measurements, and first-principles simulations. Our INS measurements on single crystals mapped the four-dimensional dynamical structure factor, S (Q ,E ) , for several compositions and temperatures. Our results show that both Ir and Os impurities lead to the formation of a weakly dispersive resonance vibrational mode, in the energy range of the acoustic phonon dispersions of the FeSi host. We also show that Ir doping, which introduces free carriers, leads to softened interatomic force constants compared to doping with Os, which is isoelectronic to Fe. We analyze the phonon S (Q ,E ) from INS through a Green's-function model incorporating the phonon self-energy based on first-principles density functional theory simulations, and we study the disorder-induced lifetimes on large supercells. Calculations of the quasiparticle spectral functions in the doped system reveal the hybridization between the resonance and the acoustic phonon modes. Our results demonstrate a strong interaction of the host acoustic dispersions with the resonance mode, likely leading to the large observed suppression in lattice thermal conductivity.

  8. Control of oxygen octahedral rotation in BiFeO3 films using modulation of SrRuO3 bottom electrode layer

    NASA Astrophysics Data System (ADS)

    Lee, Sungsu; Jo, Ji Young

    2015-03-01

    Oxygen octahedral rotation of multiferroic BiFeO3 (BFO) has attracted great attention due to changes of electrical and magnetic properties. Coupling of octahedral rotation in BFO-bottom electrode layer interface remains unexplored. Recently, there have been reported the control of octahedral rotation in SrRuO3 (SRO) film on SrTiO3 (001) substrate by coherently controlling the oxygen pressure during growth and interfacial coupling. Here we demonstrate that the octahedral rotation of BFO film is changed using tetragonal a0a0c- tilted-SRO bottom electrodes. In this work, BFO/SRO heterostructure is fabricated to SrTiO3 (001) single crystal substrates by pulsed laser deposition at different oxygen partial pressures. The rotation pattern of FeO6 and the structural symmetry are identified from half-integer reflections using high-resolution X-ray diffraction. The effects depending on octahedral tilting of BFO films on the magnetic and ferroelectric properties will be presented.

  9. Redox controls on Ni-Fe-PGE mineralization and Re/Os fractionation during serpentinization of abyssal peridotite

    NASA Astrophysics Data System (ADS)

    Foustoukos, Dionysis I.; Bizimis, Michael; Frisby, Carl; Shirey, Steven B.

    2015-02-01

    Awaruite (Ni2Fe to Ni3Fe) is often used to infer fugacity and redox gradients in hydrothermally altered peridotites. However, discrepant petrological and thermodynamic data suggest that the fO2-fS2 stability field of awaruite is not well constrained. In this study, we assess the thermodynamic properties of awaruite and re-evaluate the Fe-Ni-S systematics of hydrothermally altered peridotites. New experimental data indicate that awaruite is stable at higher fO2 than previously thought, supporting the common occurrence of awaruite in the reaction zone of modern and ancient ultramafic-hosted hydrothermal vent systems. Awaruite is known to catalyze the abiogenic synthesis of methane during active serpentinization, contributing to methanogenesis at modern oceanic hydrothermal systems and potentially on early Earth. The enhanced stability field of awaruite determined here suggests that abiogenic methanogenesis may be active at a broad range of redox conditions. Serpentinized peridotites also contain platinum-group element (PGE)-Re sulfides and metal alloys that can be derived from desulfurization of primary mantle sulfides under low fS2. Thermodynamic calculations suggest that Os will exist as metal and Re as ReS2 in the redox stability field of awaruite. Under a relatively broad range of fS2-fO2 conditions, hydrothermal alteration and desulfurization of primary mantle may produce open system behavior in the Re/Os system and variable Re-PGE ratios and contribute over time to the Os isotopic heterogeneity of the mantle, through subduction and recycling of altered oceanic lithosphere. PGE-metal alloys occur at such low abundances in peridotite that they often are nearly impossible to find. The stability of awaruite at higher fO2 suggests that it can coexist with Os-Ir-Pt metal alloys, making it an important indicator mineral for their presence in hydrothermally altered peridotites.

  10. Quasi-two-dimensional noncollinear magnetism in the Mott insulator Sr2F2Fe2OS2

    NASA Astrophysics Data System (ADS)

    Zhao, Liang L.; Wu, Shan; Wang, Jiakui K.; Hodges, J. P.; Broholm, C.; Morosan, E.

    2013-01-01

    The magnetism of Sr2F2Fe2OS2 was examined through neutron powder diffraction and thermodynamic and transport measurements. Quasi-two-dimensional magnetic order develops below TN=106(2) K with an in-plane correlation length exceeding 310 Å and an out-of-plane correlation length of just 17(3) Å. The data are consistent with a two-k structure with k1=(1/2,0,1/2) and k2=(0,1/2,1/2) and an ordered moment of 3.3(1)μB oriented along the in-plane components of k. This structure is composed of orthogonal antiferromagnetic chains intersecting at superexchange-mediating O sites. Density functional theory also points to this structure and a narrower Fe 3d band than for the iron pnictides from which electronic correlations produce a Mott insulator.

  11. Unification of the pressure and composition dependence of superconductivity in Ru substituted BaFe2As2

    NASA Astrophysics Data System (ADS)

    Devidas, T. R.; Mani, Awadhesh; Sharma, Shilpam; Vinod, K.; Bharathi, A.; Sundar, C. S.

    2014-05-01

    Temperature dependent high pressure electrical resistivity studies have been carried out on Ba(Fe1-x Rux)2As2 single crystals with x=0.12, 0.26 and 0.35, which correspond to under-doped, optimally doped and over-doped composition regimes, respectively. The evolution of structural/magnetic (TS-M) and superconducting transition (Tc) temperatures, with pressure for various compositions has been obtained. The normal state resistivity has been analyzed in terms of a model that incorporates both spin fluctuations and the opening of the gap in the spin density wave (SDW) phase. It is shown that Tc scales with the strength of the spin fluctuation, B, and TS-M scales with the SDW gap parameter, Δ. This provides a prescription for the unification of the composition and pressure induced superconductivity in BaFe2As2.

  12. Optical properties of epitaxial BiFeO3 thin film grown on SrRuO3-buffered SrTiO3 substrate

    PubMed Central

    2014-01-01

    The BiFeO3 (BFO) thin film was deposited by pulsed-laser deposition on SrRuO3 (SRO)-buffered (111) SrTiO3 (STO) substrate. X-ray diffraction pattern reveals a well-grown epitaxial BFO thin film. Atomic force microscopy study indicates that the BFO film is rather dense with a smooth surface. The ellipsometric spectra of the STO substrate, the SRO buffer layer, and the BFO thin film were measured, respectively, in the photon energy range 1.55 to 5.40 eV. Following the dielectric functions of STO and SRO, the ones of BFO described by the Lorentz model are received by fitting the spectra data to a five-medium optical model consisting of a semi-infinite STO substrate/SRO layer/BFO film/surface roughness/air ambient structure. The thickness and the optical constants of the BFO film are obtained. Then a direct bandgap is calculated at 2.68 eV, which is believed to be influenced by near-bandgap transitions. Compared to BFO films on other substrates, the dependence of the bandgap for the BFO thin film on in-plane compressive strain from epitaxial structure is received. Moreover, the bandgap and the transition revealed by the Lorentz model also provide a ground for the assessment of the bandgap for BFO single crystals. PMID:24791162

  13. Optical properties of epitaxial BiFeO3 thin film grown on SrRuO3-buffered SrTiO3 substrate.

    PubMed

    Xu, Ji-Ping; Zhang, Rong-Jun; Chen, Zhi-Hui; Wang, Zi-Yi; Zhang, Fan; Yu, Xiang; Jiang, An-Quan; Zheng, Yu-Xiang; Wang, Song-You; Chen, Liang-Yao

    2014-01-01

    The BiFeO3 (BFO) thin film was deposited by pulsed-laser deposition on SrRuO3 (SRO)-buffered (111) SrTiO3 (STO) substrate. X-ray diffraction pattern reveals a well-grown epitaxial BFO thin film. Atomic force microscopy study indicates that the BFO film is rather dense with a smooth surface. The ellipsometric spectra of the STO substrate, the SRO buffer layer, and the BFO thin film were measured, respectively, in the photon energy range 1.55 to 5.40 eV. Following the dielectric functions of STO and SRO, the ones of BFO described by the Lorentz model are received by fitting the spectra data to a five-medium optical model consisting of a semi-infinite STO substrate/SRO layer/BFO film/surface roughness/air ambient structure. The thickness and the optical constants of the BFO film are obtained. Then a direct bandgap is calculated at 2.68 eV, which is believed to be influenced by near-bandgap transitions. Compared to BFO films on other substrates, the dependence of the bandgap for the BFO thin film on in-plane compressive strain from epitaxial structure is received. Moreover, the bandgap and the transition revealed by the Lorentz model also provide a ground for the assessment of the bandgap for BFO single crystals. PMID:24791162

  14. Thermoelectric and electrical properties of Ba0.5Sr0.5Co x Ru x Fe(12-2 x)O19 ferrite*

    NASA Astrophysics Data System (ADS)

    Singh, Charanjeet; Jaroszewski, Maciej; Bindra Narang, Sukhleen; Ravinder, D.

    2016-04-01

    Thermoelectric and electrical characteristics investigation of M-type hexagonal ferrite, Ba0.5Sr0.5CoxRuxFe(12-2x)O19 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2), have been carried out from 303 K to 473 K. The static current density-electric field characteristics have been measured at room temperature. The Seebeck coefficient indicates n-type behavior at lower substitution and p-type conduction at higher substitution. The different electrical parameters are affected by change in grain size with substitution of Co2+ and Ru4+ ions. The existence of polarons is confirmed from increase in conductivity with frequency. The static conduction due to applied electric field is discussed qualitatively in terms of space charge limited current, ionic hopping, Poole-Frenkel and Schottky-Richardson mechanisms. The large current density has been observed at higher substitution. Contribution to the Topical Issue "Materials for Dielectric Applications", edited by Maciej Jaroszewski and Sabu Thomas.

  15. Positive exchange-bias and giant vertical hysteretic shift in La0.3Sr0.7FeO3/SrRuO3 bilayers

    PubMed Central

    Rana, Rakesh; Pandey, Parul; Singh, R. P.; Rana, D. S.

    2014-01-01

    The exchange-bias effects in the mosaic epitaxial bilayers of the itinerant ferromagnet (FM) SrRuO3 and the antiferromagnetic (AFM) charge-ordered La0.3Sr0.7FeO3 were investigated. An uncharacteristic low-field positive exchange bias, a cooling-field driven reversal of positive to negative exchange-bias and a layer thickness optimised unusual vertical magnetization shift were all novel facets of exchange bias realized for the first time in magnetic oxides. The successive magnetic training induces a transition from positive to negative exchange bias regime with changes in domain configurations. These observations are well corroborated by the hysteretic loop asymmetries which display the modifications in the AFM spin correlations. These exotic features emphasize the key role of i) mosaic disorder induced subtle interplay of competing AFM-superexchange and FM double exchange at the exchange biased interface and, ii) training induced irrecoverable alterations in the AFM spin structure. PMID:24569516

  16. Managing magnetization and antiferromagnetic coupling in epitaxially grown magnetic oxide heterostructures of (Ga,Fe)2O3 and SrRuO3

    NASA Astrophysics Data System (ADS)

    Lee, Jihye; Jo, William; Meny, Christian; Roulland, Francois; Viart, Nathalie

    2011-03-01

    We have grown b-axis oriented epitaxial (Ga,Fe)2O3 (GFO) thin films on (111) oriented SrRuO3 (SRO) by pulsed laser deposition to know spin interaction in multilayer system. The easy axis of magnetization of the GFO is located on the plane of the thin films. On the other hand, SRO has unique anisotropic properties on various crystallographic directions in their structure. Magnetic properties of the films were measured as a function of temperature and external magnetic field by a superconducting quantum interference magnetometer. Curie temperature of SRO and GFO was measured at 150K and 370K, respectively. According to the direction of external magnetic field, the magnetic moment value of the GFO/SRO heterostructures show different behavior due to antiferromagnetic coupling. This research was supported by Leading Foreign Research Institute Recruitment Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education, Science and Technology(MEST) (2010-00453)

  17. Chalcophile and platinum-group element distribution in the Ultramafic series of the Stillwater Complex, MT, USA—implications for processes enriching chromite layers in Os, Ir, Ru, and Rh

    NASA Astrophysics Data System (ADS)

    Barnes, Sarah-Jane; Pagé, P.; Prichard, H. M.; Zientek, M. L.; Fisher, P. C.

    2016-01-01

    All of the rocks from the Ultramafic series of the Stillwater Complex are enriched in PGE relative to most mafic magmas. Furthermore, the chromite layers are particularly enriched in IPGE (Os, Ir, and Ru) and Rh. This enrichment appears to be a common characteristic of ultramafic rocks from many types of settings, layered intrusions, ophiolites, and zoned complexes. We have carried out a petrological, mineralogical, and geochemical study to assess how the enrichment occurred in the case of the Stillwater Complex and applied our results to the chromite layers of the Bushveld and Great Dyke complexes. The minerals that now host the PGE are laurite and fine-grained intergrowths of pentlandite, millerite, and chalcopyrite. The laurite occurs as inclusions in chromite, and mass balance calculations indicate that it hosts most of the Os, Ir, and Ru. The sulfide minerals occur both as inclusions in chromite and as interstitial grains. The sulfides host much of the Pd and Rh. The IPGE and Rh correlate with Cr but not with S or Se, indicating that these elements were not collected by a sulfide liquid. Palladium, Cu, and Se correlate with each other, but not with S. The low S/Se (<1500) of the whole rock and magnetite rims around the sulfides indicate some S has been lost from the rocks. We conclude that to account for all observations, the IPGE and Rh were originally collected by chromite, and subsequently, small quantities of base metal sulfide liquid was added to the chromite layers from the overlying magma. The IPGE and Rh in the chromite diffused from the chromite into the base metal sulfides and converted some of the sulfides to laurite.

  18. Investigation of the synthesis, activation, and isosteric heats of CO2 adsorption of the isostructural series of metal-organic frameworks M3(BTC)2 (M = Cr, Fe, Ni, Cu, Mo, Ru).

    PubMed

    Wade, Casey R; Dincă, Mircea

    2012-07-14

    The synthesis, activation, and heats of CO(2) adsorption for the known members of the M(3)(BTC)(2) (HKUST-1) isostructural series (M = Cr, Fe, Ni, Zn, Ni, Cu, Mo) were investigated to gain insight into the impact of CO(2)-metal interactions for CO(2) storage/separation applications. With the use of modified syntheses and activation procedures, improved BET surface areas were obtained for M = Ni, Mo, and Ru. The zero-coverage isosteric heats of CO(2) adsorption were measured for the Cu, Cr, Ni, Mo, and Ru analogues and gave values consistent with those reported for MOFs containing coordinatively unsaturated metal sites, but lower than for amine functionalized materials. Notably, the Ni and Ru congeners exhibited the highest CO(2) affinities in the studied series. These behaviors were attributed to the presence of residual guest molecules in the case of Ni(3)(BTC)(2)(Me(2)NH)(2)(H(2)O) and the increased charge of the dimetal secondary building unit in [Ru(3)(BTC)(2)][BTC](0.5). PMID:22539456

  19. Oxygen trapped by rare earth tetrahedral clusters in Nd4FeOS6: Crystal structure, electronic structure, and magnetic properties

    DOE PAGESBeta

    Lin, Qisheng; Taufour, Valentin; Zhang, Yuemei; Wood, Max; Drtina, Thomas; Bud’ko, Sergey L.; Canfield, Paul C.; Miller, Gordon J.

    2015-05-22

    Single crystals of Nd4FeOS6 were grown from an Fe-S eutectic solution. Single crystal X-ray diffraction analysis revealed a Nd4MnOSe6-type structure (P63mc, a = 9.2693(1) Å, c = 6.6650(1) Å, V = 495.94(1) Å3, Z = 2), featuring parallel chains of face-sharing [FeS6x1/2]4- trigonal antiprisms and interlinked [Nd4OS3]4+ cubane-like clusters. Oxygen atoms were found to be trapped by Nd4 clusters in the [Nd4OS3]4+ chains. Structural differences among Nd4MnOSe6-type Nd4FeOS6 and the related La3CuSiS7- and Pr8CoGa3-type structures have been described. Magnetic susceptibility measurements on Nd4FeOS6 suggested the dominance of antiferromagnetic interactions at low temperature, but no magnetic ordering down to 2 Kmore » was observed. Spin-polarized electronic structure calculations revealed magnetic frustration with dominant antiferromagnetic interactions.« less

  20. Oxygen trapped by rare earth tetrahedral clusters in Nd4FeOS6: Crystal structure, electronic structure, and magnetic properties

    NASA Astrophysics Data System (ADS)

    Lin, Qisheng; Taufour, Valentin; Zhang, Yuemei; Wood, Max; Drtina, Thomas; Bud'ko, Sergey L.; Canfield, Paul C.; Miller, Gordon J.

    2015-09-01

    Single crystals of Nd4FeOS6 were grown from an Fe-S eutectic solution. Single crystal X-ray diffraction analysis revealed a Nd4MnOSe6-type structure (P63mc, a=9.2693(1) Å, c=6.6650(1)Å, V=495.94(1) Å3, Z=2), featuring parallel chains of face-sharing [FeS6×1/2]4- trigonal antiprisms and interlinked [Nd4OS3]4+ cubane-like clusters. Oxygen atoms were found to be trapped by Nd4 clusters in the [Nd4OS3]4+ chains. Structural differences among Nd4MnOSe6-type Nd4FeOS6 and the related La3CuSiS7- and Pr8CoGa3-type structures have been described. Magnetic susceptibility measurements on Nd4FeOS6 suggested the dominance of antiferromagnetic interactions at low temperature, but no magnetic ordering down to 2 K was observed. Spin-polarized electronic structure calculations revealed magnetic frustration with dominant antiferromagnetic interactions.

  1. Atomic site preferences and its effect on magnetic structure in the intermetallic borides M{sub 2}Fe(Ru{sub 0.8}T{sub 0.2}){sub 5}B{sub 2} (M=Sc, Ti, Zr; T=Ru, Rh, Ir)

    SciTech Connect

    Brgoch, Jakoah; Mahmoud, Yassir A.; Miller, Gordon J.

    2012-12-15

    The site preference for a class of intermetallic borides following the general formula M{sub 2}Fe(Ru{sub 0.8}T{sub 0.2}){sub 5}B{sub 2} (M=Sc, Ti, Zr; T=Ru, Rh, Ir), has been explored using ab initio and semi-empirical electronic structure calculations. This intermetallic boride series contains two potential sites, the Wyckoff 2c and 8j sites, for Rh or Ir to replace Ru atoms. Since the 8j site is a nearest neighbor to the magnetically active Fe atom, whereas the 2c site is a next nearest neighbor, the substitution pattern should play an important role in the magnetic structure of these compounds. The substitution preference is analyzed based on the site energy and bond energy terms, both of which arise from a tight-binding evaluation of the electronic band energy, and are known to influence the locations of atoms in extended solids. According to these calculations, the valence electron-rich Rh and Ir atoms prefer to occupy the 8j site, a result also corroborated by experimental evidence. Additionally, substitution of Rh or Ir at the 8j site results in a modification of the magnetic structure that ultimately results in larger local magnetic moment on the Fe atoms. - Graphical abstract: The site preference for electron rich atoms to occupy the 8j (gray) site is identified in these intermetallic borides, while the magnetic structure is modified as a function of the substituted atoms band center. Highlights: Black-Right-Pointing-Pointer We identify the energetics dictating the site preference in a series of intermetallic borides. Black-Right-Pointing-Pointer Establish substitution rules for use in future directed synthetic preparations. Black-Right-Pointing-Pointer Identified changes in magnetic structure that accompany the site preference.

  2. Varied roles of Pb in transition-metal PbMO3 perovskites (M = Ti, V, Cr, Mn, Fe, Ni, Ru)

    NASA Astrophysics Data System (ADS)

    Goodenough, John B.; Zhou, Jianshi

    2015-06-01

    Different structural chemistries resulting from the Pb2+ lone-pair electrons in the PbMO3 perovskites are reviewed. The Pb2+ lone-pair electrons enhance the ferroelectric transition temperature in PbTiO3, stabilize vanadyl formation in PbVO3, and induce a disproportionation reaction of CrIV in PbCrO3. A Pb2+ + NiIV = Pb4+ + NiII reaction in PbNiO3 stabilizes the LiNbO3 structure at ambient pressure, but an A-site Pb4+ in an orthorhombic perovskite PbNiO3 is stabilized at modest pressures at room temperature. In PbMnO3, a ferroelectric displacement due to the lone pair electron effect is minimized by the spin-spin exchange interaction and the strong octahedral site preference of the MnIV/III cation. PbRuO3 is converted under pressure from the defective pyrochlore to the orthorhombic (Pbnm) perovskite structure where Pb-Ru interactions via a common O -2p orbital stabilize at low temperature a metallic Imma phase at ambient pressure. Above Pc ≃ ~32 GPa, a covalent Pb-Ru bond is formed by Pb2+ + RuIV = Pb4+ + RuII electron sharing.

  3. Magnetic ordering and physical stability of X2Mn1+xSn1-x (X=Ru, Os, Co, Rh, Ni, Pd, Cu, and Ag) Heusler alloys from a first-principles study

    NASA Astrophysics Data System (ADS)

    Li, Chun-Mei; Hu, Qing-Miao; Yang, Rui; Johansson, Börje; Vitos, Levente

    2013-07-01

    The magnetic ordering and its effect on the physical stability of X2Mn1+xSn1-x (0≤x≤0.5, and X=Ru, Os, Co, Rh, Ni, Pd, Cu, and Ag) Heusler alloys are investigated systematically by the use of first-principles method. It is found that the ferromagnetic (FM) coupling between Mn on Mn sublattice (Mn1) and Mn on Sn sublattice (Mn2) is favorable over the antiferromagnetic (AFM) coupling for X with the number of valence electrons [Nv(X)] of 8 and 9, and vice versa for X with Nv(X)=10 and 11, originated from the competition of the exchange interactions between X-Mn2 and Mn1-Mn2. In comparison with the FM Mn1-Mn2 coupling, the AFM coupling decreases significantly the shear elastic constant C' but increases slightly C44, which results in increasing elastic anisotropy (A=C44/C') and consequently may facilitate the tetragonal shear lattice deformation. The hybridization of the minority electronic states between X d and Sn p plays a dominant role on the orientation of the magnetic coupling. The smaller change of the density of states in the Fermi level, induced by the lattice distortion for C', corresponds to the softer C' as well as the larger A in the AFM state than the FM one.

  4. Oxygen trapped by rare earth tetrahedral clusters in Nd{sub 4}FeOS{sub 6}: Crystal structure, electronic structure, and magnetic properties

    SciTech Connect

    Lin, Qisheng; Taufour, Valentin; Zhang, Yuemei; Wood, Max; Drtina, Thomas; Bud’ko, Sergey L.; Canfield, Paul C.; Miller, Gordon J.

    2015-09-15

    Single crystals of Nd{sub 4}FeOS{sub 6} were grown from an Fe–S eutectic solution. Single crystal X-ray diffraction analysis revealed a Nd{sub 4}MnOSe{sub 6}-type structure (P6{sub 3}mc, a=9.2693(1) Å, c=6.6650(1)Å, V=495.94(1) Å{sup 3}, Z=2), featuring parallel chains of face-sharing [FeS{sub 6×1/2}]{sup 4−} trigonal antiprisms and interlinked [Nd{sub 4}OS{sub 3}]{sup 4+} cubane-like clusters. Oxygen atoms were found to be trapped by Nd{sub 4} clusters in the [Nd{sub 4}OS{sub 3}]{sup 4{sub +}} chains. Structural differences among Nd{sub 4}MnOSe{sub 6}-type Nd{sub 4}FeOS{sub 6} and the related La{sub 3}CuSiS{sub 7}− and Pr{sub 8}CoGa{sub 3}-type structures have been described. Magnetic susceptibility measurements on Nd{sub 4}FeOS{sub 6} suggested the dominance of antiferromagnetic interactions at low temperature, but no magnetic ordering down to 2 K was observed. Spin-polarized electronic structure calculations revealed magnetic frustration with dominant antiferromagnetic interactions. - Graphical abstract: Trapping of oxygen in Nd{sub 4} tetrahedral clusters results in the formation of the Nd{sub 4}MnOSe{sub 6}-type Nd{sub 4}FeOS{sub 6}, in contrast to the La{sub 3}CuSiS{sub 7}-type oxygen-free Nd{sub 4}FeS{sub 7} and related Pr{sub 8}CoGa{sub 3}-type structures. Complex magnetic frustration inhibits magnetic ordering at low temperature. - Highlights: • Single crystals of Nd{sub 4}FeOS{sub 6} were grown using self-flux method. • Oxygen was found trapped by Nd{sub 4} tetrahedral clusters. • Comparison with two closely related structural types were discussed. • Magnetic measurements revealed antiferromagnetic (AFM) interaction. • VASP calculations confirmed strong magnetic frustration in AFM model.

  5. Oxygen trapped by rare earth tetrahedral clusters in Nd4FeOS6: Crystal structure, electronic structure, and magnetic properties

    SciTech Connect

    Lin, Qisheng; Taufour, Valentin; Zhang, Yuemei; Wood, Max; Drtina, Thomas; Bud’ko, Sergey L.; Canfield, Paul C.; Miller, Gordon J.

    2015-05-22

    Single crystals of Nd4FeOS6 were grown from an Fe-S eutectic solution. Single crystal X-ray diffraction analysis revealed a Nd4MnOSe6-type structure (P63mc, a = 9.2693(1) Å, c = 6.6650(1) Å, V = 495.94(1) Å3, Z = 2), featuring parallel chains of face-sharing [FeS6x1/2]4- trigonal antiprisms and interlinked [Nd4OS3]4+ cubane-like clusters. Oxygen atoms were found to be trapped by Nd4 clusters in the [Nd4OS3]4+ chains. Structural differences among Nd4MnOSe6-type Nd4FeOS6 and the related La3CuSiS7- and Pr8CoGa3-type structures have been described. Magnetic susceptibility measurements on Nd4FeOS6 suggested the dominance of antiferromagnetic interactions at low temperature, but no magnetic ordering down to 2 K was observed. Spin-polarized electronic structure calculations revealed magnetic frustration with dominant antiferromagnetic interactions.

  6. Chemical pressure tuning of URu2Si2 via isoelectronic substitution of Ru with Fe

    SciTech Connect

    Das, Pinaki; Kanchanavatee, N.; Helton, J. S.; Huang, K.; Baumbach, R. E.; Bauer, E. D.; White, B. D.; Burnett, V. W.; Maple, M. B.; Lynn, J. W.; Janoschek, M.

    2015-02-26

    We have used specific heat and neutron diffraction measurements on single crystals of URu2–xFexSi₂ for Fe concentrations x ≤ 0.7 to establish that chemical substitution of Ru with Fe acts as “chemical pressure” Pch as previously proposed by Kanchanavatee et al. [Phys. Rev. B 84, 245122 (2011)] based on bulk measurements on polycrystalline samples. Neutron diffraction reveals a sharp increase of the uranium magnetic moment at x = 0.1, reminiscent of the behavior at the “hidden order” to large moment antiferromagnetic (LMAFM) phase transition observed at a pressure Px ≈ 0.5-0.7 GPa in URu₂Si₂. Using the unit cell volume determined from our measurements and an isothermal compressibility κT = 5.2×10⁻³ GPa⁻¹ for URu₂Si₂, we determine the chemical pressure Pch in URu2-xFexSi₂ as a function of x. The resulting temperature T-chemical pressure Pch phase diagram for URu2-xFexSi₂ is in agreement with the established temperature T-external pressure P phase diagram of URu₂Si₂.

  7. Re-Os isotopic ages of pyrite and chemical composition of magnetite from the Cihai magmatic-hydrothermal Fe deposit, NW China

    NASA Astrophysics Data System (ADS)

    Huang, Xiao-Wen; Zhou, Mei-Fu; Qi, Liang; Gao, Jian-Feng; Wang, Yu-Wang

    2013-12-01

    The Eastern Tianshan Orogenic Belt of the Central Asian Orogenic Belt and the Beishan terrane of the Tarim Block, NW China, host numerous Fe deposits. The Cihai Fe deposit (>90 Mt at 45.6 % Fe) in the Beishan terrane is diabase-hosted and consists of the Cihai, Cinan, and Cixi ore clusters. Ore minerals are dominantly magnetite, pyrite, and pyrrhotite, with minor chalcopyrite, galena, and sphalerite. Gangue minerals include pyroxene, garnet, hornblende and minor plagioclase, biotite, chlorite, epidotite, quartz, and calcite. Pyrite from the Cihai and Cixi ore clusters has similar Re-Os isotope compositions, with ˜14 to 62 ppb Re and ≤10 ppt common Os. Pyrrhotite has ˜5 to 39 ppb Re and ˜0.6 ppb common Os. Pyrite has a mean Re-Os model age of 262.3 ± 5.6 Ma ( n = 13), in agreement with the isochron regression of 187Os vs. 187Re. The Re-Os age (˜262 Ma) for the Cihai Fe deposit is within uncertainty in agreement with a previously reported Rb-Sr age (268 ± 25 Ma) of the hosting diabase, indicating a genetic relationship between magmatism and mineralization. Magnetite from the Cihai deposit has Mg, Al, Ti, V, Cr, Co, Ni, Mn, Zn, Ga, and Sn more elevated than that of typical skarn deposits, but both V and Ti contents lower than that of magmatic Fe-Ti-V deposits. Magnetite from these two ore clusters at Cihai has slightly different trace element concentrations. Magnetite from the Cihai ore cluster has relatively constant trace element compositions. Some magnetite grains from the Cixi ore cluster have higher V, Ti, and Cr than those from the Cihai ore cluster. The compositional variations of magnetite between the ore clusters are possibly due to different formation temperatures. Combined with regional tectonic evolution of the Beishan terrane, the Re-Os age of pyrite and the composition of magnetite indicate that the Cihai Fe deposit may have derived from magmatic-hydrothermal fluids related to mafic magmatism, probably in an extensional rift environment.

  8. Mössbauer and magnetic studies of bulk and fine-powder SrRu O3 and Sr-Cu-Ru O3 systems

    NASA Astrophysics Data System (ADS)

    Felner, Israel; Nomura, Kiyoshi; Nowik, Israel

    2006-02-01

    SrRuO3 is a ferromagnet, TC=165K . Due to difference in grain sizes, ceramic bulk and fine-powder (prepared by the sol-gel procedure) of SrRuO3 , have different coercive fields. The Fe57 doped Mössbauer effect spectra (MS) of powder SrRuO3 exhibit distinct magnetic hyperfine sextets up to TC , while none is observed at 90K in the bulk material. This is probably a result of the fact that the Fe57 probe resides in the Sr and Ru sites for powder and bulk SrRuO3 , respectively. Due to the shorter Sr-Ru distance, the Fe57 ions in the Sr site are exposed to an exchange field from the Ru magnetically ordered ions, much more than the iron in the Ru site. The Fe57 MS spectra of Sr1-xCuxRuO3 and SrRu1-yCuyO3 systems behave similarly to powder and bulk SrRuO3 , respectively. The magnetic properties of the two systems are discussed. The above results served as the basic explanation for the peculiar magnetic behavior of the magneto superconducting RuEu1.5Ce0.5Sr2Cu2O10 in the temperature range 90-165K .

  9. Fragility of ferromagnetic double exchange interactions and pressure tuning of magnetism in 3d–5d double perovskite Sr₂FeOsO₆

    SciTech Connect

    Veiga, L. S. I.; Fabbris, G.; van Veenendaal, M.; Souza-Neto, N. M.; Feng, H. L.; Yamaura, K.; Haskel, D.

    2015-06-19

    The ability to tune exchange (magnetic) interactions between 3d transition metals in perovskite structures has proven to be a powerful route to discovery of novel properties. Here we demonstrate that the introduction of 3d-5d exchange pathways in double perovskites enables additional tunability, a result of the large spatial extent of 5d wave functions. Using x-ray probes of magnetism and structure at high pressure, we show that compression of Sr₂FeOsO₆ drives an unexpected continuous change in the sign of Fe-Os exchange interactions and a transition from antiferromagnetic to ferrimagnetic order. We analyze the relevant electron-electron interactions, shedding light into fundamental differences with the more thoroughly studied 3d-3d systems.

  10. Fragility of ferromagnetic double exchange interactions and pressure tuning of magnetism in 3d–5d double perovskite Sr₂FeOsO₆

    DOE PAGESBeta

    Veiga, L. S. I.; Fabbris, G.; van Veenendaal, M.; Souza-Neto, N. M.; Feng, H. L.; Yamaura, K.; Haskel, D.

    2015-06-19

    The ability to tune exchange (magnetic) interactions between 3d transition metals in perovskite structures has proven to be a powerful route to discovery of novel properties. Here we demonstrate that the introduction of 3d-5d exchange pathways in double perovskites enables additional tunability, a result of the large spatial extent of 5d wave functions. Using x-ray probes of magnetism and structure at high pressure, we show that compression of Sr₂FeOsO₆ drives an unexpected continuous change in the sign of Fe-Os exchange interactions and a transition from antiferromagnetic to ferrimagnetic order. We analyze the relevant electron-electron interactions, shedding light into fundamental differencesmore » with the more thoroughly studied 3d-3d systems.« less

  11. The End of Monterey Submarine Canyon Incision and Potential River Source Areas-Os, Nd, and Pb Isotope Constraints from Hydrogenetic Fe-Mn Crusts

    NASA Astrophysics Data System (ADS)

    Conrad, T. A.; Nielsen, S.; Ehrenbrink, B. P. E.; Blusztajn, J.; Hein, J. R.; Paytan, A.

    2015-12-01

    The Monterey Canyon off central California is the largest submarine canyon off North America and is comparable in scale to the Grand Canyon. The age and history of the Monterey Canyon are poorly constrained due to thick sediment cover and sediment disruption from turbidity currents. To address this deficit we analyzed isotopic proxies (Os, Pb, Nd) from hydrogenetic ferromanganese (Fe-Mn) crusts, which grow over millions of years on elevated rock surfaces by precipitation of metals from seawater. Fe-Mn crusts were studied from Davidson Seamount near the base of the Monterey submarine fan, the Taney Seamount Chain, and from Hoss Seamount, which serves as a regional control (Fig.). Fe-Mn crusts were dated using Os isotope ratios compared to those that define the Cenozoic Os isotope seawater curve. Four Fe-Mn crust samples from Davidson and Taney Seamounts deviate from the Os isotopic seawater curve towards radiogenic values after 4.5±1 Ma. Osmium is well mixed in the global ocean and is not subject to significant diffusive reequilibration in Fe-Mn crusts. We therefore attribute deviations from the Os isotope seawater curve to large-scale terrestrial input that ended about 4.5±1 Ma. The two Davidson samples also show more radiogenic Nd isotope values from about 4.5±1 Ma. Lead isotopes in one Davidson Seamount crust, measured by LA-ICPMS, deviate from regional values after 4.5±1 Ma for about 500 ka towards terrestrial sources. The Taney Seamount Fe-Mn crust does not deviate from regional Nd nor Pb isotope values due to its greater distance from Monterey Canyon and the shorter marine residence times of Nd and Pb. Isotope plots of our crust data and compiled data for potential source rocks indicate that the river that carved Monterey Canyon carried sediment with values closer to the Sierra Nevada than to a Colorado Plateau source, with cessation of major riverine input occurring approximately 4.5±1 Ma, an age that we interpret as the end of the Monterey Canyon

  12. Heavy-impurity resonance, hybridization, and phonon spectral functions in Fe1-xMxSi, M=Ir,Os

    SciTech Connect

    Delaire, O.; Al-Qasir, Iyad I.; May, Andrew F.; Sales, Brian C.; Niedziela, Jennifer L.; Ma, Jie; Matsuda, Masaaki; Abernathy, Douglas L.; Berlijn, Tom

    2015-03-31

    The vibrational behavior of heavy substitutional impurities (M=Ir,Os) in Fe1-xMxSi (x = 0, 0.02, 0.04, 0.1) was investigated with a combination of inelastic neutron scattering (INS), transport measurements, and first-principles simulations. In this paper, our INS measurements on single-crystals mapped the four-dimensional dynamical structure factor, S(Q;E), for several compositions and temperatures. Our results show that both Ir and Os impurities lead to the formation of a weakly dispersive resonance vibrational mode, in the energy range of the acoustic phonon dispersions of the FeSi host. We also show that Ir doping, which introduces free carriers and increases electron-phonon coupling, leads to softened interatomic force-constants compared to doping with Os, which is isoelectronic to Fe. We analyze the phonon S(Q,E) from INS through a Green's function model incorporating the phonon self-energy based on first-principles density functional theory (DFT) simulations. Calculations of the quasiparticle spectral functions in the doped system reveal the hybridization between the resonance and the acoustic phonon modes. Finally, our results demonstrate a strong interaction of the host acoustic dispersions with the resonance mode, likely leading to the large observed suppression in lattice thermal conductivity.

  13. Magnetic properties of RT2Zn20; R = rare earth, T = Fe, Co, Ru, Os and Ir

    SciTech Connect

    Jia, Shuang

    2008-01-01

    It is well known that rare earth intermetallic compounds have versatile, magnetic properties associated with the 4f electrons: a local moment associated with the Hund's rule ground state is formed in general, but a strongly correlated, hybridized state may also appear for specific 4f electronic configuration (eg. for rare earth elements such as Ce or Yb). On the other hand, the conduction electrons in rare earth intermetallic compounds, certainly ones associated with non hybridizing rare earths, usually manifest non-magnetic behavior and can be treated as a normal, non-interacted Fermi liquid, except for some 3d-transition metal rich binary or ternary systems which often manifest strong, itinerant, d electron dominant magnetic behavior. Of particular interest are examples in which the band filling of the conduction electrons puts the system in the vicinity of a Stoner transition: such systems, characterized as nearly or weakly ferromagnet, manifest strongly correlated electronic properties [Moriya, 1985]. For rare earth intermetallic compounds, such systems provide an additional versatility and allow for the study of the behaviors of local moments and hybridized moments which are associated with 4f electron in a correlated conduction electron background.

  14. Adsorptive Separation of Methanol-Acetone on Isostructural Series of Metal-Organic Frameworks M-BTC (M = Ti, Fe, Cu, Co, Ru, Mo): A Computational Study of Adsorption Mechanisms and Metal-Substitution Impacts.

    PubMed

    Wu, Ying; Chen, Huiyong; Xiao, Jing; Liu, Defei; Liu, Zewei; Qian, Yu; Xi, Hongxia

    2015-12-01

    The adsorptive separation properties of M-BTC isostructural series (M = Ti, Fe, Cu, Co, Ru, Mo) for methanol-acetone mixtures were investigated by using various computational procedures of grand canonical Monte Carlo simulations (GCMC), density functional theory (DFT), and ideal adsorbed solution theory (IAST), following with comprehensive understanding of adsorbate-metal interactions on the adsorptive separation behaviors. The obtained results showed that the single component adsorptions were driven by adsorbate-framework interactions at low pressures and by framework structures at high pressures, among which the mass effects, electrostatics, and geometric accessibility of the metal sites also played roles. In the case of methanol-acetone separation, the selectivity of methanol on M-BTCs decreased with rising pressures due to the pressure-dependent separation mechanisms: the cooperative effects between methanol and acetone hindered the separation at low pressures, whereas the competitive effects of acetone further resulted in the lower selectivity at high pressures. Among these M-BTCs, Ti and Fe analogues exhibited the highest thermodynamic methanol/acetone selectivity, making them promising for adsorptive methanol/acetone separation processes. The investigation provides mechanistic insights on how the nature of metal centers affects the adsorption properties of MOFs, and will further promote the rational design of new MOF materials for effective gas mixture separation. PMID:26581027

  15. Bulk modulus and specific heat of B-site doped (La0.3Pr0.7)0.65Ca0.35Mn1-xBxO3 (B=Fe, Cr, Ru, Al, Ga)

    NASA Astrophysics Data System (ADS)

    Srivastava, Archana; Thakur, Rasna; Gaur, N. K.

    2014-04-01

    Specific heat (Cp) thermal expansion (α) and Bulk modulus (BT) of lightly doped Rare Earth manganites (La0.3Pr0.7)0.65Ca0.35Mn1-xBxO3 (B3+ = Fe3+,Cr3+,Ga3+,Al3+,Ru4+); (0.3Fe0.03O3 as a function of temperature (10K≤T≤ 200K) is found to be in agreement with the published data. The trend of variation of Debye temperature with B-site cationic radius is predicted probably for the first time for the B-site doped rare earth manganites.

  16. Molecule-based magnets formed by bimetallic three-dimensional oxalate networks and chiral tris(bipyridyl) complex cations. The series [ZII(bpy)3][ClO4][MIICrIII(ox)3] (ZII = Ru, Fe, Co, and Ni; MII = Mn, Fe, Co, Ni, Cu, and Zn; ox = oxalate dianion).

    PubMed

    Coronado, E; Galán-Mascarós, J R; Gómez-García, C J; Martínez-Agudo, J M

    2001-01-01

    The synthesis, structure, and physical properties of the series of molecular magnets formulated as [ZII(bpy)3][ClO4][MIICrIII(ox)3] (ZII = Ru, Fe, Co, and Ni; MII = Mn, Fe, Co, Ni, Cu, and Zn; ox = oxalate dianion) are presented. All the compounds are isostructural to the [Ru(bpy)3][ClO4][MnCr(ox)3] member whose structure (cubic space group P4(1)32 with a = 15.506(2) A, Z = 4) consists of a three-dimensional bimetallic network formed by alternating MII and CrIII ions connected by oxalate anions. The identical chirality (lambda in the solved crystal) of all the metallic centers determines the 3D chiral structure adopted by these compounds. The anionic 3D sublattice leaves some holes where the chiral [Z(bpy)3]2+ and ClO4- counterions are located. These compounds behave as soft ferromagnets with ordering temperatures up to 6.6 K and coercive fields up to 8 mT. PMID:11195368

  17. Synthesis, crystal structure investigation and magnetism of the complex metal-rich boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (x=0.88-1; y=0-1) with Th{sub 7}Fe{sub 3}-type structure

    SciTech Connect

    Misse, Patrick R.N.; Mbarki, Mohammed; Fokwa, Boniface P.T.

    2012-08-15

    Powder samples and single crystals of the new complex boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (x=0.88-1; y=0-1) have been synthesized by arc-melting the elements under purified argon atmosphere on a water-cooled copper crucible. The products, which have metallic luster, were structurally characterized by single-crystal and powder X-ray diffraction as well as EDX measurements. Within the whole solid solution range the hexagonal Th{sub 7}Fe{sub 3} structure type (space group P6{sub 3}mc, no. 186, Z=2) was identified. Single-crystal structure refinement results indicate the presence of chromium at two sites (6c and 2b) of the available three metal Wyckoff sites, with a pronounced preference for the 6c site. An unexpected Rh/Ru site preference was found in the Ru-rich region only, leading to two different magnetic behaviors in the solid solution: The Rh-rich region shows a temperature-independent (Pauli) paramagnetism whereas an additional temperature-dependent paramagnetic component is found in the Ru-rich region. - Graphical abstract: The new complex boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (x=0.88-1; y=0-1) has been synthesized by arc melting the elements under purified argon atmosphere. Beside the 3d/4d site preference within the whole solid solution, an unexpected Rh/Ru site preference was found in the Ru-rich region only, leading to two different magnetic behaviors: The Rh-rich region shows a temperature-independent (Pauli) paramagnetism whereas an additional temperature-dependent paramagnetic component is found in the Ru-rich region. Highlights: Black-Right-Pointing-Pointer Synthesis of a new boride series fulfilling Vegard Acute-Accent s rule. Black-Right-Pointing-Pointer 3d/4d site preference. Black-Right-Pointing-Pointer Unexpected Ru/Rh site preference. Black-Right-Pointing-Pointer Rh-rich region is Pauli paramagnetic. Black-Right-Pointing-Pointer Ru-rich region is Pauli and temperature-dependent paramagnetic.

  18. Structural and physical properties of layered oxy-arsenides LnRuAsO (Ln=La, Nd, Sm, Gd)

    SciTech Connect

    McGuire, Michael A.; May, Andrew F.; Sales, Brian C.

    2012-07-15

    Polycrystalline samples of LaRuAsO, NdRuAsO, SmRuAsO, and GdRuAsO have been synthesized and studied using powder x-ray diffraction, electrical transport, magnetization, and heat capacity measurements. Variations in structural properties across the series reveal a trend toward more ideal tetrahedral coordination around Ru as the size of the rare earth element is reduced. The lattice parameters of these Ru compounds show a more anisotropic response to variation in Ln than their Fe analogs, and significant anisotropy in thermal expansion is also observed. Transport measurements show metallic behavior, and carrier concentrations near 10{sup 21}-10{sup 22} electrons per cm{sup 3} are inferred from simple analysis of Hall effect measurements. Anomalies in resistivity, magnetization, and heat capacity indicate antiferromagnetic ordering of rare earth moments at 5 K for GdRuAsO, 4.5 K for SmRuAsO, and <2K for NdRuAsO. Magnetization measurements on LaRuAsO show no evidence of a magnetic moment on Ru. Observed behaviors are compared to those reported for similar Fe and Ru compounds. - Graphical abstract: Analysis of crystal structure, electrical transport, magnetic susceptibility, and heat capacity of LaRuAsO, NdRuAsO, SmRuAsO, and GdRuAsO. Highlights: Black-Right-Pointing-Pointer Experimental investigation of LaRuAsO, NdRuAsO, SmRuAsO, and GdRuAsO. Black-Right-Pointing-Pointer Anisotropic lattice response to changing Ln radius and temperature. Black-Right-Pointing-Pointer Ru coordination becomes more ideal as Ln radius is reduced. Black-Right-Pointing-Pointer Transport measurements reveal metallic conduction dominated by electrons. Black-Right-Pointing-Pointer Magnetic measurements indicate antiferromagnetic ordering Nd, Sm, and Gd moments.

  19. Structural Analysis of Novel Antiferromagnetic Material CeRu2Al10 and Its Related Compounds under Pressure

    NASA Astrophysics Data System (ADS)

    Kawamura, Yukihiro; Hayashi, Junichi; Takeda, Keiki; Sekine, Chihiro; Tanida, Hiroshi; Sera, Masafumi; Nishioka, Takashi

    2016-04-01

    We performed synchrotron X-ray studies of orthorhombic CeRu2Al10 and its related compounds CeT2Al10 (T = Fe, Os) and RRu2Al10 (R = La, Yb, Lu). The results of the X-ray studies indicate that all of the compounds retain their orthorhombic crystal structures and that their lattice parameters all monotonically decrease with pressure; that is, no structural changes or distortions occur below 10 GPa within the experimental accuracy of this study. In addition, we evaluated the bulk moduli of the compounds, which are mainly affected by the transition metal in RT2Al10 systems. All of the compounds exhibited crystal structures that were harder along the b-axis than along the a- or c-axes. Furthermore, anisotropic shrinkage induced a difference between the physical pressure of CeRu2Al10 and the chemical pressure of Ce(Ru1-xFex)2Al10 (0 ≤ x ≤ 1). Thus, the physical properties of CeRu2Al10 under pressure were observed to be strongly affected by crystal structure shrinkage along the a- and c-axes.

  20. London penetration depth measurements in Ba (Fe1-xTx)2As2(T=Co,Ni,Ru,Rh,Pd,Pt,Co+Cu) superconductors

    SciTech Connect

    Gordon, Ryan T.

    2011-01-01

    The London penetration depth has been measured in various doping levels of single crystals of Ba(Fe1-xTx)2As2 (T=Co,Ni,Ru,Rh,Pd,Pt,Co+Cu) superconductors by utilizing a tunnel diode resonator (TDR) apparatus. All in-plane penetration depth measurements exhibit a power law temperature dependence of the form Δλab(T) = CTn, indicating the existence of low-temperature, normal state quasiparticles all the way down to the lowest measured temperature, which was typically 500 mK. Several different doping concentrations from the Ba(Fe1-xTx)2As2 (T=Co,Ni) systems have been measured and the doping dependence of the power law exponent, n, is compared to results from measurements of thermal conductivity and specific heat. In addition, a novel method has been developed to allow for the measurement of the zero temperature value of the in-plane penetration depth, λab(0), by using TDR frequency shifts. By using this technique, the doping dependence of λab(0) has been measured in the Ba(Fe1-xCox)2As2 series, which has allowed also for the construction of the doping-dependent superfluid phase stiffness, ρs(T) = [λ(0)/λ(T)]2. By studying the effects of disorder on these superconductors using heavy ion irradiation, it has been determined that the observed power law temperature dependence likely arises from pair-breaking impurity scattering contributions, which is consistent with the proposed s±-wave symmetry of the superconducting gap in the dirty scattering limit. This hypothesis is supported by the measurement of an exponential temperature dependence of the penetration depth in the intrinsically clean LiFeAs, indicative of a nodeless superconducting gap.

  1. Ru/FTO: Heterogeneous catalyst for glycerol hydrogenolysis

    NASA Astrophysics Data System (ADS)

    Samad, Wan Zurina; Isahak, Wan Nor Roslam Wan; Liew, Kin Hong; Nordin, Norazzizi; Yarmo, Mohd Ambar; Yusop, Muhammad Rahimi

    2014-09-01

    An introduction of Fluorine-doped tin oxide (FTO) as new catalyst support with Ru metal had enhanced the conversion and selectivity for glycerol hydrogenolysis. A small cluster of Ru were highly dispersed and intercalated over FTO via simple chemical mixture and reduction method. In comparison with various metal (Pd, Os, Cu), Ru/FTO catalyst showed the highest conversion (100%) and highly selectivity of 1,2-propanediol (94%) in the hydrogenolysis of glycerol. The reaction was optimally conducted at 150 °C, 20 bar of H2 pressure and at 8 hours. Ru/FTO catalyst was ascribed as active catalyst due to the amphoteric sites of FTO and small size of Ru metal. This provides high surface concentration of reduction process that involves the chemical bond dissociation in the glycerol hydrogenolysis.

  2. Reactions of HC triple bond CCMe sub 2 NHCOR alkynes with M sub 3 (CO) sub 12 carbonyls (M = Ru, R = C sub 6 H sub 9 , Ph; M = Os, R = C sub 6 H sub 9 ). Synthesis and crystal structure of Ru sub 4 (CO) sub 11 (HC triple bond CCMe sub 2 NHCOC sub 6 H sub 9 ), a butterfly cluster showing an interaction between a wingtip metal and the amide CO

    SciTech Connect

    Predieri, G.; Tiripicchio, A.; Camellini, M.T.; Costa, M. ); Sappa, E. )

    1990-06-01

    The alkynes HC{triple bond}CCMe{sub 2}NHCOR react with M{sub 3}(CO){sub 12} (M = Ru or Os) giving, upon oxidative addition, the expected hydrides ({mu}-H)M{sub 3}(CO){sub 9}({mu}{sub 3}-{eta}{sup 2}-C{triple bond}CCMe{sub 2}NHCOR) and the unprecedented butterfly clusters M{sub 4}(CO){sub 11}({mu}{sub 4}-{eta}{sup 2}-HC{triple bond}CCME{sub 2}NHCOR). These complexes have been characterized by spectroscopic studies; the structure of the ruthenium butterfly cluster with R = C{sub 6}H{sub 9} has been determined by X-ray diffraction methods. Crystals, containing CHCl{sub 3} as solvation molecules, are triclinic with Z = 2 in a unit cell of dimensions a = 13.521 (6), b = 14.617 (6), c = 9.049 (5) {angstrom}, {alpha} = 79.28 (2), {beta} = 108.79 (2), {gamma} = 111.85 (2){degree}.

  3. Chemically modified electrode with a film of nano ruthenium oxides stabilizing high valent RuO(4)(-) species and its redox-selective sequential transformation to polynuclear ruthenium oxide-metallocyanates.

    PubMed

    Kumar, Annamalai Senthil; Tanase, Tomoaki; Zen, Jyh-Myng

    2009-12-01

    High-valent Ru(VII)O(4)(-) (perruthenate) is a short-lived species in aqueous solutions (pH 1-14) and has scarcely been studied through electrochemistry. By a potential-controlled oxidative deposition method at 1 V vs Ag/AgCl using RuCl(3) in a pH 2 KCl-HCl buffer solution, chemically modified glassy carbon (GCE) and indium tin oxide (ITO) electrodes were successfully prepared with a film of hydrous nano ruthenium oxides RuO(2) and RuO(3), stabilizing the high-valent perruthenate anion (Ru(VII)-RuO(x)-CME, x = 2 and 3, CME = chemically modified electrode). The electrodes showed three distinct redox peaks corresponding to Ru(2)O(3)/RuO(2), RuO(2)/RuO(3), and RuO(4)(2-)/RuO(4)(-) redox processes at pH 2, like the classical RuO(2) electrodes in alkaline conditions. Solid state UV-visible spectra of the ITO/Ru(VII)-RuO(x)-CME showed characteristic absorption very close to chemically generated authentic RuO(4)(-) species in alkaline solution. Further, redox-controlled sequential procedures yielded polynuclear ruthenium oxide-hexacyanometallate films (RuO-MCN-CME, M = Fe and Ru), in which Ru(VII)-RuO(x)-CME acted as a specific template. A controlled-potential activation (>1 V) of Ru(VII)-RuO(x)-CME, stabilizing the key RuO(4)(-) species, in a solution of [Fe(CN)(6)](3-) or [Ru(CN)(6)](4-), should be a critical step for the formation of polynuclear RuO-MCN matrix. PMID:19928948

  4. Structural and magnetic phase transitions in TbRuAsO and DyRuAsO

    NASA Astrophysics Data System (ADS)

    McGuire, Michael; May, Andrew; Garlea, Ovidiu; Sales, Brian

    2013-03-01

    The compounds LnRuAsO (Ln = lanthanide) are isoelectronic, isostructural, 4 d transition metal analogues of the parent phases of 1111-type iron superconductors, but display markedly different behaviors. Recent results from crystallographic and physical properties measurements on TbRuAsO and DyRuAsO reveal particularly unusual properties in these materials. Analysis of low temperature x-ray and neutron powder diffraction data indicate a symmetry-lowering crystallographic phase transition in DyRuAsO at 25 K, and ordering of rare-earth magnetic moments at 7.0 and 10.5 K for TbRuAsO and DyRuAsO, respectively. The structural distortion observed in DyRuAsO (to space group Pmmn) is different than the well-known distortion that occurs in LnFeAsO. In addition, the findings indicate some coupling between the magnetism and the lattice, and hints of Ru magnetism are observed. A response to the structural transition is apparent in the magnetic susceptibility, and the associated heat capacity anomaly responds strongly to a magnetic field. Research supported by the US Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division (synthesis, physical and structural properties), and Scientific User Facilities Division (neutron diffraction, HB2A high-resolution powde

  5. T3RU test

    MedlinePlus

    ... sample is needed. How to Prepare for the Test Your health care provider will tell you if you need to stop taking medicines that may affect the test result. Drugs that can increase T3RU levels include: ...

  6. All-atom force field for molecular dynamics simulations on organotransition metal solids and liquids. Application to M(CO)(n) (M = Cr, Fe, Ni, Mo, Ru, or W) compounds.

    PubMed

    Bernardes, Carlos E S; Canongia Lopes, José N; Minas da Piedade, Manuel E

    2013-10-31

    A previously developed OPLS-based all-atom force field for organometallic compounds was extended to a series of first-, second-, and third-row transition metals based on the study of M(CO)(n) (M = Cr, Fe, Ni, Mo, Ru, or W) complexes. For materials that are solid at ambient temperature and pressure (M = Cr, Mo, W) the validation of the force field was based on reported structural data and on the standard molar enthalpies of sublimation at 298.15 K, experimentally determined by Calvet-drop microcalorimetry using samples corresponding to a specific and well-characterized crystalline phase: Δ(sub)H(m)° = 72.6 ± 0.3 kJ·mol(–1) for Cr(CO)(6), 73.4 ± 0.3 kJ·mol(–1) for Mo(CO)(6), and 77.8 ± 0.3 kJ·mol(–1) for W(CO)(6). For liquids, where problems of polymorphism or phase mixtures are absent, critically analyzed literature data were used. The force field was able to reproduce the volumetric properties of the test set (density and unit cell volume) with an average deviations smaller than 2% and the experimentally determined enthalpies of sublimation and vaporization with an accuracy better than 2.3 kJ·mol(–1). The Lennard-Jones (12-6) potential function parameters used to calculate the repulsive and dispersion contributions of the metals within the framework of the force field were found to be transferable between chromium, iron, and nickel (first row) and between molybdenum and ruthenium (second row). PMID:24079472

  7. The role of intermolecular interactions in the assemblies of Fe{sup II} and Co{sup II} tetrakis-isothiocyanatometalates with tris(1,10-phenanthroline)-Ru{sup II}: Crystal structures of two dual-metal assemblies featuring octahedral cationic and tetrahedral anionic modules

    SciTech Connect

    Ghazzali, Mohamed Langer, Vratislav; Ohrstroem, Lars

    2008-09-15

    Two new dual-metal assemblies: 2[Ru(phen){sub 3}]{sup 2+}.[Fe(SCN){sub 4}]{sup 2-}.2SCN{sup -}.4H{sub 2}O 1 and [Ru(phen){sub 3}]{sup 2+}.[Co(SCN){sub 4}]{sup 2-}2, (phen:1,10-phenanthroline), have been prepared and their structures were characterized by X-ray diffraction. In 1, the cationic octahedral enantiomers are arranged with a {lambda}{delta}{lambda}{delta}{lambda} sequence supported by {pi}-{pi} stacking and the anionic inorganic tetrahedral units are oriented between these stacks by interacting with the nearby water molecules through strong O-H...O and O-H...S hydrogen bonds. In 2, homochiral double helices in the b-direction are revealed, with tetrakis-isothiocyanate Co{sup II} anions arranged in the crystal to furnish one-dimensional (1D)-helical chains with S...S intermolecular interactions at 3.512(2) and 3.966(2) A supporting [Ru(phen){sub 3}]{sup 2+}{lambda}- and {delta}-helices with Ru...Ru shortest distance of 8.676(7) A. In both 1 and 2, the supramolecular assembly is maintained by C-H...S hydrogen bonds extending between the phenanthroline aromatic carbons in the cationic nodes and the sulphur atoms of the isothiocyanates anions. Analysis of S...S interactions in isothiocyanate containing compounds using Cambridge structural database (CSD) showed an angle dependence categorizing these interactions into 'type-I' and 'type-II'. - Graphical abstract: Side projection in 2 showing the crankshaft caused by S...S interactions in [Co(NCS){sub 4}]{sup 2-} in-between [Ru{sup II}(phen){sub 3}]{sup 2+} helices. Only isothiocyanates arms of [Co(NCS){sub 4}]{sup 2-} that are part of S...S interactions are shown and [Ru{sup II}(phen){sub 3}]{sup 2+} are presented as polyhedra.

  8. Rapid growth of localized nature of carriers in the Kondo semiconductor CeFe2Al10 with nonmagnetic ground state due to small Rh doping

    NASA Astrophysics Data System (ADS)

    Tanida, H.; Nakamura, M.; Sera, M.; Nishioka, T.; Matsumura, M.

    2015-12-01

    We examined the chemical doping effect on the Kondo semiconductor CeFe2Al10 with a nonmagnetic ground state by means of the magnetic susceptibility, specific heat, electrical resistivity, and thermopower. The effect of Ru doping on the ground state is small. On the other hand, by a small amount of Rh doping, the magnetic susceptibility is strongly enhanced along the orthorhombic a axis, and a Curie-Weiss behavior is observed in a wide temperature range. The low-temperature specific heat is also strongly enhanced by the doping, and a metallic ground state is realized at low temperatures. These results suggest the collapse of the spin and charge gap due to the suppression of the c -f hybridization effect. From the results of a crystalline electric field analysis on the magnetic susceptibility of Ce (Fe1 -xRhx )2Al10 , it was revealed that the Rh-doping effect on the c -f hybridization effect is anisotropic, especially for the a axis. Similar doping effects are seen in the Rh-doped CeRu2Al10 , Ir-doped CeOs2Al10 , and Si-doped CeRu2Al10 . From these results, we conclude that the collapse of the spin and charge gap by such an excess electron doping is one of the universal features of the Kondo semiconductor Ce T2Al10 (T = Fe, Ru, and Os).

  9. RU-79115 (Aventis Pharma).

    PubMed

    Annedi, S C; Kotra, L P

    2001-06-01

    Aventis Pharma AG is investigating a series of novel coumarin DNA gyrase B inhibitors, including RU-79115, as potential treatments for bacterial infections. These inhibitors have displayed potent inhibitory activity in vitro against DNA supercoiling by DNA gyrase B and have antibacterial activity. Good antibacterial activity against vancomycin- and teicoplanin-resistant enterococci was observed with most analogs (where the 3-acylamino residue was replaced with reversed isosteres). Amide derivatives were also active against novobiocin-resistant strains [335149]. RU-79115 has shown activity against Gram-positive bacteria, particularly staphylococci and enterococci, and its activity compares favorably to vancomycin. Against oxacillin- and ofloxacin-resistant staphylococci, RU-79115 had MIC50 values 7.5-fold lower than eperezolid and significantly lower than vancomycin. In vivo data suggest that the compound is safe and carries a satisfactory pharmacokinetic profile [216256], [340969], [376199]. The compound is the most potent in the series which also includes RU-78535 and RU-64135 [340969], [341039]. PMID:11572652

  10. PGE abundance and Re-Os isotope Systematics of Native-Fe-Bearing Basaltic Rocks and Their Carbonaceous Crustal Contaminants: Insights into magma plumbing-system dynamics in LIPs

    NASA Astrophysics Data System (ADS)

    Howarth, G. H.; Day, J. M.; Goodrich, C. A.; Pernet-Fisher, J.; Pearson, D. G.; Taylor, L. A.

    2014-12-01

    Native-Fe grains form in basaltic melts at highly reducing conditions (Fe-bearing basalts are useful natural analogues for studying PGE pre-concentration mechanisms, and the potential for PGE additions to magmas from crustal sources. Here, we present PGE LA-ICP-MS data for Fe-alloy, cohenite, and sulfide for a suite of Siberian and Disko Island native-Fe basalts, in combination with whole-rock PGE data for all known occurrences. The Siberian native-Fe alloys are characterized by highly variable PGE concentrations (1-30 ppm total PGEs), distinct low Os abundances, and PGE profiles similar to those of the nearby Noril'sk sulfide ores. In contrast, the Disko Island alloys are characterized by total PGE concentrations of 1-10 ppm and distinct positive Os and Re anomalies in extended PGE profiles. The Bühl basalts contain low PGE concentrations (~20 ppb). In order to understand contamination contributions, Os-isotopes analyses have been performed. Preliminary whole-rock 187Os/188Os data for high metal content samples from Siberia (0.33606 ± 37) and Disko (0.15402 ± 15) indicate high-time integrated Re/Os. The Re anomalies observed in extended PGE profiles of the Disko Island samples may reflect a potential crustal contribution to the overall PGE budget, through the addition of carbonaceous material. Whereas the Siberian samples contain abundant carbonaceous xenoliths, there is no apparent PGE contribution from crustal materials. Therefore, the role of crustal contamination is important in forming the native-Fe alloys, but the interaction

  11. Role of Ru in electrochromic effect during domain-inversion in LiNbO 3 crystals

    NASA Astrophysics Data System (ADS)

    Liu, De'an; Zhi, Ya'nan; Yan, Aimin; Luan, Zhu; Liu, Liren

    2006-08-01

    Recently, a new phenomenon of eletrochromic effect during domain-inversion has been observed both in doubly doped LiNbO 3:Fe:Ru and singly doped LiNbO 3:Ru crystals. Therefore, it is reasonable to be thought that the dopant of Ru is critical for eletrochromic effect. In this paper, The transmission spectra of different kinds of LiNbO 3 crystals are compared and analyzed for further demonstration that it is the exchange of valence states between Ru 3+ and Ru 4+ which lead to electrochromism effect.

  12. Meteorite - Impact Melt Mixing: PGE and Re-Os Evidence from the Morokweng Impact, South Africa

    NASA Astrophysics Data System (ADS)

    Hart, R.; Andreoli, M.; Cloete, M.; McDonald, I.; Carlson, R. W.; Tredoux, M.

    2001-12-01

    Preserved within the 870m thick impact melt sheet of the 144 Ma Morokweng impact structure, South Africa (1,2) are small (mm-cm) inclusions that are interpreted to be remnants of the impactor. Inclusions are disseminated throughout the melt sheet and consist of ultramafic silicate clasts with segregations of Ni-rich sulfides and oxides. The silicate component in the inclusions displays remnant fabric and, where unaltered, has mineral compositions consistent with ordinary chondrites (3). The sulfide-oxide component of the inclusions is Ni-rich, has high PGE contents (Ir = 16.7 x chondrite) and fractionated PGE ratios compared to chondrites and to the bulk impact melt which reflects the signature of the ordinary chondrite impactor (4). Specifically, the oxides show depletion in Pd, while the sulfide is slightly enriched in Rh and Pt and strongly enriched in Pd relative to Ir and Ru. Significantly, Ru and Ir (the high temperature PGE's) are not fractionated from one another. Initial Os isotopic compositions of the inclusion sulfides and oxides (0.1335 - 0.1358) are slightly more radiogenic than found in the melt rock (0.1301 - 0.1324), but both are substantially less radiogenic than a sample of the basement granite (0.259). The 1/Os vs 187Os/188Os correlation displayed by the bulk melt rocks is consistent with the presence of 1-3 wt% chondritic impactor in the crustal melt. The more radiogenic Os found in the inclusion minerals indicates that the inclusions contain a larger crustal PGE component than the melt rock. Though Os concentration is well correlated with Os isotopic composition in the melt rock, Re concentration is not. Thus, simple binary mixing between crustal melt and meteorite cannot explain the Re-Os systematics. The Re-Os and PGE fractionation observed in inclusion minerals suggests that meteorite-impact melt mixing occurred first through chemical exchange between oxidized melt and reduced, metal or sulfur-rich, impactor. Lithophile elements (e.g. Fe

  13. Mifepristone (RU486): a review.

    PubMed

    Mahajan, D K; London, S N

    1997-12-01

    Through an online search of MEDLINE, the authors reviewed the literature on the development of mifepristone (RU-486); RU-486's mechanism of action, pharmacodynamics, and distribution; the physiologic action of RU-486; potential new uses for RU-486; and its current use as both an abortifacient and therapy for endometriosis, leiomyoma, breast cancer, and meningioma. RU-486 is an 11beta-dimethyl-amino-phenyl derivative of norethindrone with a high affinity for P and glucocorticoid receptors. Receptor binding is not followed by the transcription of P-dependent genes. RU-486 effectively blocks P receptors in the placenta, resulting in the termination of pregnancy. It has also been used to treat leiomyomata, endometriosis, advanced breast cancer, and meningioma. The following therapeutic uses of RU-486 are discussed: the termination of early pregnancy, treatment with RU-486 in combination with prostaglandins, the termination of second-trimester pregnancy, cervical ripening, labor induction, postcoital contraception, uterine leiomyomata, endometriosis, breast cancer, and meningioma. PMID:9418681

  14. Ru-Containing Magnetically Recoverable Catalysts: A Sustainable Pathway from Cellulose to Ethylene and Propylene Glycols.

    PubMed

    Manaenkov, Oleg V; Mann, Joshua J; Kislitza, Olga V; Losovyj, Yaroslav; Stein, Barry D; Morgan, David Gene; Pink, Maren; Lependina, Olga L; Shifrina, Zinaida B; Matveeva, Valentina G; Sulman, Esther M; Bronstein, Lyudmila M

    2016-08-24

    Biomass processing to value-added chemicals and biofuels received considerable attention due to the renewable nature of the precursors. Here, we report the development of Ru-containing magnetically recoverable catalysts for cellulose hydrogenolysis to low alcohols, ethylene glycol (EG) and propylene glycol (PG). The catalysts are synthesized by incorporation of magnetite nanoparticles (NPs) in mesoporous silica pores followed by formation of 2 nm Ru NPs. The latter are obtained by thermal decomposition of ruthenium acetylacetonate in the pores. The catalysts showed excellent activities and selectivities at 100% cellulose conversion, exceeding those for the commercial Ru/C. High selectivities as well as activities are attributed to the influence of Fe3O4 on the Ru(0)/Ru(4+) NPs. A facile synthetic protocol, easy magnetic separation, and stability of the catalyst performance after magnetic recovery make these catalysts promising for industrial applications. PMID:27484222

  15. Ion probe measurements of Os, Ir, Pt, and Au in individual phases of iron meteorites

    NASA Astrophysics Data System (ADS)

    Hsu, Weibiao; Huss, Gary R.; Wasserburg, G. J.

    2000-03-01

    We have developed a technique to measure abundances of Os, Ir, Pt, and Au in situ in Fe-Ni metal on a microscale using secondary-ion mass spectrometry. A Cs + beam is used to generate negative secondary ions, and interferences from molecular ions are eliminated by a combination of 40 eV of energy filtering and a mass resolution of ˜1900. Ion yields for Fe, Co, Ni, and the PGEs vary considerably from spot to spot in meteoritic metal samples. Ion yield variations for Os and Ir correlate strongly with the Fe ion yield, that for Pt is weakly correlated, and that for Au is essentially uncorrelated. From ion yields for meteorite standards and the correlations with Fe ion yield, it is possible to obtain concentrations of Os, Ir, Pt, and Au in meteorite samples. Using this technique, a Cs + beam current of 10 nA gives a spatial resolution of 10-20 μm and detection limits of less than 1 ppm for Os, less than 0.1 ppm for Ir, and 10-20 ppb for Pt and Au. With refinement, it should be possible to measure Rh, Pd, and Ag and to improve the spatial resolution. However, Re, Ru, W, and Hf can only be measured as positive secondary ions. We have measured the abundances of Os, Ir, Pt, and Au in kamacite, taenite, and/or plessite in five iron meteorites: Canyon Diablo (IA), Cape York (Agpalilik) (IIIA), Colomera (IIE), Cruz del Aire (Anom), and Wallapai (IID). Our measurements show that Os, Ir, Pt, and Au partition preferentially into taenite relative to kamacite during slow cooling. Measured abundance ratios (taenite/kamacite) range from ˜1.3 to ˜2.1 for Os, Ir, and Pt, and from ˜2 to ˜6 for Au. These ratios are consistent with those determined recently by laser-ablation ICPMS, but differ significantly from those determined by earlier workers. Low-temperature taenite/kamacite distribution coefficients inferred from our data are ˜2.1 for Os, ˜1.6 for Ir, ˜1.9 for Pt, and ˜6 for Au. PGEs are not enriched in taenite as much as Ni. Partitioning is controlled by the interplay of

  16. Bulk modulus and specific heat of B-site doped (La{sub 0.3}Pr{sub 0.7}){sub 0.65}Ca{sub 0.35}Mn{sub 1−x}B{sub x}O{sub 3} (B=Fe, Cr, Ru, Al, Ga)

    SciTech Connect

    Srivastava, Archana; Thakur, Rasna; Gaur, N. K.

    2014-04-24

    Specific heat (C{sub p}) thermal expansion (α) and Bulk modulus (B{sub T}) of lightly doped Rare Earth manganites (La{sub 0.3}Pr{sub 0.7}){sub 0.65}Ca{sub 0.35}Mn{sub 1−x}B{sub x}O{sub 3} (B{sup 3+} = Fe{sup 3+},Cr{sup 3+},Ga{sup 3+},Al{sup 3+},Ru4+); (0.3Fe{sub 0.03}O{sub 3} as a function of temperature (10K≤T≤ 200K) is found to be in agreement with the published data. The trend of variation of Debye temperature with B-site cationic radius is predicted probably for the first time for the B-site doped rare earth manganites.

  17. Geochemistry and Re-Os geochronology of the organic-rich sedimentary rocks in the Jingtieshan Fe-Cu deposit, North Qilian Mountains, NW China

    NASA Astrophysics Data System (ADS)

    Yang, Xiuqing; Zhang, Zuoheng; Li, Chao; Duan, Shigang; Jiang, Zongsheng

    2016-04-01

    The Jingtieshan Group in the North Qilian Mountains, NW China, is dominantly composed of banded iron formations (BIFs), copper deposits and organic-rich sedimentary rocks (ORS, carbonaceous phyllite). X-ray diffraction analysis of the ORS shows the mineral assemblage to be quartz + clay minerals. The total organic carbon contents show a range of 0.44-1.72%. Here we present the results of the geochemistry and Re-Os geochronology of the ORS from the Jingtieshan Group. The high values of Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), Plagioclase Index of Alteration (PIA), and Th/U ratio, indicate intense weathering. The Al2O3/TiO2, Zr/Sc, Th/Sc, La/Th ratios, high rare earth elements abundances, light rare earth elements enrichment (normalized to chondrite), and distinctly negative Eu anomalies, suggest that the Jingtieshan Group ORS were derived mainly from felsic volcanic units. The new Re-Os isochron age of 1308 ± 100 Ma (2σ, n = 6, MSWD = 23) broadly overlap with the previous published ages determined using Sm-Nd and U-Pb isotope systems. The new age represents the depositional age of the Jingtieshan Group, as well that of BIF in the Jingtieshan area. Furthermore, the initial 187Os/188Os ratios (0.44 ± 0.07) indicate that the Os in the seawater was dominantly derived from hydrothermal fluids (∼75%). The Ce anomaly (Ce/Ce∗ = 0.95-1.00) and V/(V + Ni) ratios (0.71-0.86), as well as the lack of enrichment in redox-sensitive trace elements such as U, V, Zn, Pb, Cu, Ni, Cr, Co and Mn, together with the presence of overlying BIF, suggest that the Jingtieshan area represents a ferruginous deep-water succession. This, and intense submarine hydrothermal activities contributed to the deposition of the Jingtieshan BIF.

  18. Simulating Ru L3-edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    SciTech Connect

    Van Kuiken, Benjamin E.; Valiev, Marat; Daifuku, Stephanie L.; Bannan, Caitlin; Strader, Matthew L.; Cho, Hana; Huse, N.; Schoenlein, R. W.; Govind, Niranjan; Khalil, Munira

    2013-05-01

    Ruthenium L2,3-edge X-ray absorption (XA) spectroscopy probes transitions from core 2p orbitals to the 4d levels of the atom and is a powerful tool for interrogating the local electronic and molecular structure around the metal atom. However, a molecular-level interpretation of the Ru L2,3-edge spectral lineshapes is often complicated by spin–orbit coupling (SOC) and multiplet effects. In this study, we develop spin-free time-dependent density functional theory (TDDFT) as a viable and predictive tool to simulate the Ru L3-edge spectra. We successfully simulate and analyze the ground state Ru L3-edge XA spectra of a series of RuII and RuIII complexes: [Ru(NH3)6]2+/3+, [Ru(CN)6]4-/3-, [RuCl6]4-/3-, and the ground (1A1) and photoexcited (3MLCT) transient states of [Ru(bpy)3]2+ and Ru(dcbpy)2(NCS)2 (termed N3). The TDDFT simulations reproduce all the experimentally observed features in Ru L3-edge XA spectra. The advantage of using TDDFT to assign complicated Ru L3-edge spectra is illustrated by its ability to identify ligand specific charge transfer features in complex molecules. We conclude that the B3LYP functional is the most reliable functional for accurately predicting the location of charge transfer features in these spectra. Experimental and simulated Ru L3-edge XA spectra are presented for the transition metal mixed-valence dimers [(NC)5MII-CN-RuIII(NH3)5]- (where M = Fe or Ru) dissolved in water. We explore the spectral signatures of electron delocalization in Ru L3-edge XA spectroscopy and our simulations reveal that the inclusion of explicit solvent molecules is crucial for reproducing the experimentally determined valencies, highlighting the importance of the role of the solvent in transition metal charge transfer chemistry.

  19. CO chemisorption and dissociation at high coverages during CO hydrogenation on Ru catalysts.

    PubMed

    Loveless, Brett T; Buda, Corneliu; Neurock, Matthew; Iglesia, Enrique

    2013-04-24

    Density functional theory (DFT) and infrared spectroscopy results are combined with mechanism-based rate equations to assess the structure and thermodynamics of chemisorbed CO (CO*) and its activation during Fischer-Tropsch synthesis (FTS). CO* binding becomes weaker with increasing coverage on Ru(0001) and Ru201 clusters, but such decreases in binding energy occur at higher coverages on Ru201 clusters than on Ru(0001) surfaces (CO*/Ru = 1.55 to 0.75); such differences appear to reflect weaker repulsive interactions on the curved surfaces prevalent on small Ru201 clusters. Ru201 clusters achieve stable supramonolayer coverages (CO*/Ru > 1) by forming geminal dicarbonyls at low-coordination corner/edge atoms. CO* infrared spectra on Ru/SiO2 (~7 nm diameter) detect mobile adlayers that anneal into denser structures at saturation. Mechanism-based FTS rate equations give activation energies that reflect the CO*-saturated surfaces prevalent during catalysis. DFT-derived barriers show that CO* predominantly reacts at (111) terraces via H-assisted reactions, consistent with measured effects of H2 and CO pressures and cluster size effects on rates and O-rejection selectivities. Barriers are much higher for unassisted CO* dissociation on (111) terraces and low-coordination atoms, including step-edge sites previously proposed as active sites for CO* dissociation during FTS. DFT-derived barriers indicate that unassisted CO* dissociation is irreversible, making such steps inconsistent with measured rates. The modest activation barriers of H-assisted CO* dissociation paths remove a requirement for special low-coordination sites for unassisted CO* activation, which is inconsistent with higher rates on larger clusters. These conclusions seem generally applicable to Co, Fe, and Ru catalysts, which show similar FTS rate equations and cluster size effects. This study also demonstrates the feasibility and relevance of DFT treatments on the curved and crowded cluster surfaces where

  20. The series of carbon-chain complexes {Ru(dppe)Cp*}₂{μ-(C≡C)x} (x = 4–8, 11): Synthesis, structures, properties and some reactions

    SciTech Connect

    Bruce, Michael I.; Cole, Marcus L.; Ellis, Benjamin G.; Gaudio, Maryka; Nicholson, Brian K.; Parker, Christian R.; Skelton, Brian W.; White, Allan H.

    2015-01-28

    The construction of a series of compounds {Ru(dppe)Cp*}2(μ-C2x) (Ru*-C2x-Ru*, x = 4–8, 11)) is described. A direct reaction between RuCl(dppe)Cp* and Me3Si(Ctriple bond; length of mdashC)4SiMe3 afforded Ru*-C8-Ru* in 89% yield. The Pd(0)/Cu(I)-catalysed coupling of Ru{Ctriple bond; length of mdashCCtriple bond; length of mdashCAu(PPh3)}(dppe)Cp*Ru*-C4-Au (2 equiv.) with diiodoethyne gave Ru*-C10-Ru* (64%), or of 1 equiv. with I(Ctriple bond; length of mdashC)3I gave Ru*-C14-Ru* (36%); similarly, Ru{(Ctriple bond; length of mdashC)4Au(PPh3)}(dppe)Cp*Ru*-C8-Au and I(Ctriple bond; length of mdashC)3I gave Ru*-C22-Ru* (12%). Desilylation (TBAF) of Ru{(Ctriple bond; length of mdashC)xSiMe3}(dppe)Cp*Ru*-C2x-Si (x = 3, 4) followed by oxidative coupling [Cu(OAc)2/py] gave Ru*-C12-Ru* (82%) and Ru*-C16-Ru* (58%), respectively. Similar oxidative coupling of Ru(Ctriple bond; length of mdashCCtriple bond; length of mdashCH)(dppe)Cp* was a second route to Ru*-C8-Ru* (82%). Appropriate precursors are already known, or obtained by coupling of Ru*-C2x-Si (x = 2, 4) with AuCl(PPh3)/NaOMe [Ru*-C4-Au, 95%; Ru*-C8-Au, 74%] or from Pd(0)/Cu(I) catalysed coupling of Ru*-C2x-Au (x = 2, 3) with I(Ctriple bond; length of mdashC)2SiMe3 (Ru*-C8-Si, 64%; Ru*-C10-Si, 2%). Reactions between Ru*-C2x-Ru* (x = 3, 4) and Fe2(CO)9 gave {Fe3(CO)9}{μ3-CCtriple bond; length of mdashC[Ru(dppe)Cp*]}2Fe(C3-Ru*)2 and {Fe3(CO)9}{μ3-CCtriple bond; length of mdashC[Ru(dppe)Cp*]}{μ3-C(Ctriple bond; length of mdashC)2[Ru(dppe)Cp*]} Fe(C3-Ru*)(C5-Ru*), respectively. The redox properties of the series of complexes with 2x = 2–16 were measured and showed a diminution of the

  1. Band structures in 98Ru and 99Ru

    NASA Astrophysics Data System (ADS)

    Van Voorthuysen, E. H. Du Marchie; Devoigt, M. J. A.; Blasi, N.; Jansen, J. F. W.

    1981-03-01

    The level schemes of 98, 99Ru were studied with the reactions 98Mo(α, 3nγ) and 98Mo(α, 4nγ) at Eα = 35 to 55 MeV, using a large variety of in-beam γ-ray detection techniques and conversion-electron measurements. A search for the 3 - state was carried out with the reaction 98Ru(p, p'). The ground-state band of 98Ru was excited up to Jπ = (12) + and a negative-parity band up to (15) -. New levels in 98Ru were found at Ex = 2285 ( Jπ = 4 +), 2435 ( Jπ = (3 -, 4 +)), 2671, 3540, 4224, 4847, 4915 ( Jπ = (12) +), 4989 ( Jπ = (12 +)), 5521 ( Jπ = (13) -), 5889, 6591 ( Jπ = (15) -), and 7621 keV. New unambiguous spin and parity assignments were made for the levels at Ex = 2014 and 3852 keV, as Jπ = 3 + and 9 -, respectively. New levels in 99Ru were found at Ex = 1976, 2021 ( J π = ( {15}/{2}+) ), 2393, 2401 ( J π = ( {17}/{2}+) ), 2875 (π = (+)), 3037, 3201 ( J π = ( {23}/{2}) -), 3460 ( J = ( {17}/{2}) ), 3484 ( J π = ( {21}/{2}+) ), 3985, 4224 ( J π = ( {27}/{2}-) ), and 5359 keV. The 1070 keV, J π = {11}/{2}- level in 99Ru has a half-life of 2.8 ns. A strongly excited negative-parity band is built on this level. A positive-parity band based on the ground state was excited up to J π = ( {21}/{2}+) . The level schemes are well reproduced by the interacting boson model in the vibrational limit.

  2. Magnetic and microwave properties of CoFe/PtMn/CoFe multilayer films

    NASA Astrophysics Data System (ADS)

    Pettiford, C. I.; Zeltser, A.; Yoon, S. D.; Harri, V. G.; Vittoria, C.; Sun, N. X.

    2006-04-01

    CoFe/PtMn/CoFe films were deposited on seed layers of Ru or NiFeCr with CoFe film compositions being either Co-10 at. %Fe or Co-16 at. %Fe. Eight periods of the CoFe/PtMn/CoFe trilayers were also prepared. The magnetic properties and ferromagnetic resonance (FMR) of these films were characterized with vibrating-sample magnetometer, and field-sweep FMR system at X band (~9.5 GHz). The Ru-seeded CoFe/PtMn/CoFe sandwich films show excellent magnetic softness with a low hard axis coercivity of 2-4 Oe, an easy axis Mr/Ms of >98%, and a significantly enhanced in-plane anisotropy of 57-123 Oe when CoFe layer thickness is above 200 A˚. Contrary to what was observed in the ferromagnetic/antiferromagnetic bilayer systems that have reduced FMR linewidth with the increase of film thickness, the CoFe/PtMn/CoFe trilayers with Ru seed layer show a minimum FMR linewidth of 45 Oe at an intermediate CoFe layer thickness of 300 A˚ at ~9.5 GHz.

  3. Round table on RU486.

    PubMed

    Shallat, L

    1993-01-01

    As a non-invasive means of early abortion, RU-486 has the potential to increase women's reproductive options; at the same time, the "abortion pill" has stimulated debate about the ethics and safety of new medical technologies. When combined with a prostaglandin (PG), the success rate for RU-486 is 96% for pregnancies of up to 9 weeks' gestation. In France, over 120,000 women have used RU-486/PG to terminate pregnancy, and this regimen is now used in about 25% of abortions. Clinical trials of RU-486 are underway in Cuba, China, India, Singapore, and Zambia. The Program for Appropriate Technology has identified four considerations for introducing RU-486 to developing countries: whether abortion or menstrual regulation is legal; whether women find the method acceptable and can comply with the multiple visit treatment regimen; whether the health infrastructure can support safe method use, including prevention of misuse and provision of appropriate medical backup personnel and facilities; and whether the cost of the regimen is affordable to individuals and/or programs --conditions unlikely to be met in most such countries. Ideal would be development of a medical abortifacient that is single dose and the lowest possible dose of each drug, provokes miscarriage within a more predictable time frame with less acute and prolonged bleeding, is safe and effective beyond two months, has minimal side effects, and maximizes short-term safety and minimizes long-term effects. Technological advances are being undermined, however, by political and religious attacks on the method. Even some feminists have expressed concerns about potential long-term effects of RU-486 use. PMID:12179722

  4. Effect of Ru thickness on spin pumping in Ru/Py bilayer

    SciTech Connect

    Behera, Nilamani; Singh, M. Sanjoy; Chaudhary, Sujeet; Pandya, Dinesh K. Muduli, P. K.

    2015-05-07

    We report the effect of Ru thickness (t{sub Ru}) on ferromagnetic resonance (FMR) line-width of Ru(t{sub Ru})/Py(23 nm) bilayer samples grown on Si(100)/SiO{sub 2} substrates at room temperature by magnetron sputtering. The FMR line-width is found to vary linearly with frequency for all thicknesses of Ru, indicating intrinsic origin of damping. For Ru thicknesses below 15 nm, Gilbert-damping parameter, α is almost constant. We ascribe this behavior to spin back flow that is operative for Ru thicknesses lower than the spin diffusion length in Ru, λ{sub sd}. For thicknesses >15 nm (>λ{sub sd}), the damping constant increases with Ru thickness, indicating spin pumping from Py into Ru.

  5. Simulating Ru L3-Edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    SciTech Connect

    Kuiken, Benjamin E. Van; Valiev, Marat; Daifuku, Stephanie L.; Bannan, Caitlin; Strader, Matthew L.; Cho, Hana; Huse, Nils; Schoenlein, Robert W.; Govind, Niranjan; Khalil, Munira

    2013-04-26

    Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of RuII and RuIII complexes in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6]4- and RuII polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5MII-CN-RuIII(NH3)5] (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.

  6. Quantifying the Carbon Abundances in the Secondary Stars of SS Cygni, RU Pegasi, and GK Persei

    NASA Astrophysics Data System (ADS)

    Harrison, Thomas E.; Hamilton, Ryan T.

    2015-11-01

    We use a modified version of MOOG to generate large grids of synthetic spectra in an attempt to derive quantitative abundances for three CVs (GK Per, RU Peg, and SS Cyg) by comparing the models to moderate resolution (R ˜ 25,000) K-band spectra obtained with NIRSPEC on Keck. For each of the three systems we find solar, or slightly sub-solar values for [Fe/H], but significant deficits of carbon: for SS Cyg we find [C/Fe] = -0.50, for RU Peg [C/Fe] = -0.75, and for GK Per [C/Fe] = -1.00. We show that it is possible to use lower resolution (R ˜ 2000) spectra to quantify carbon deficits. We examine realistic veiling scenarios and find that emission from H i or CO cannot reproduce the observations.

  7. RU-486: the "abortion pill".

    PubMed

    Herranz, G

    1991-05-23

    A report sent by the Vatican to bishops' conferences throughout the world calls RU-486, the so-called abortion pill currently available in France, "a new, serious threat to human life." The report was developed at the Vatican's request by Gonzalo Herranz, a Spanish bioethicist. A cover letter to bishops' conferences from Cardinal Alfonso Lopez Trujillo, president of the Pontifical Council for the Family, suggested that the report be used "to resist the introduction of the abortion pill RU-486 into your country." Related to TU-486 and to new terminology some use to characterize its non-surgical approach to abortion is an intention "to amoralize and thereby place the transmission of human life into an ethically neutral terrain and reduce it to pure biology," says the report. The report discusses possible future uses of RU-486 as a contraceptive, stating: "Women would no longer have to worry themselves about whether they have conceived or not. Each month they would proceed to clean out their uterus chemically." The report refers to RU-486 as "a technical step forward in an area that did not need it." It says, "The abortion pill favors a woman's privacy and secret, but it condemns her to solitude." The English text from the Vatican follows. PMID:16145821

  8. Photoelectric conversion at a [Ru(bpy)3](2+)-based metallic triad anchored on ITO surface.

    PubMed

    Farran, Rajaa; Jouvenot, Damien; Loiseau, Frédérique; Chauvin, Jérôme; Deronzier, Alain

    2014-08-28

    A tri-metallic triad based on a [Ru(bpy)3](2+) moiety connected to Fe(ii) and Co(iii) bisterpyridine has been grafted on an ITO electrode by a stepwise procedure. Under visible light, in the presence of a sacrificial electron donor, the system produces electric current. The photo-current magnitude is compared to the one generated from a Co(iii)-Ru(ii) dyad and shows an increase of 40%. PMID:25002098

  9. Evolution of supercurrent path in Nb /Ru /Sr2RuO4 dc-SQUIDs

    NASA Astrophysics Data System (ADS)

    Nago, Y.; Ishiguro, R.; Sakurai, T.; Yakabe, M.; Nakamura, T.; Yonezawa, S.; Kashiwaya, S.; Takayanagi, H.; Maeno, Y.

    2016-08-01

    Phase-sensitive measurements of direct-current superconducting quantum interference devices (dc-SQUIDs) composed of Sr2RuO4 -Ru eutectic crystals have been performed to temperatures below a bulk Ru superconducting transition temperature at 0.49 K. A SQUID with Nb /Ru /Sr2RuO4 junctions fabricated on one Ru inclusion exhibits two distinct transitions due to the Ru superconducting transition and competition of proximity-induced superconducting gaps at the junctions. At sufficiently low temperatures, the SQUID interference patterns start to collapse with large phase shifts of the Fraunhofer patterns. This result indicates the influence of magnetic fluxes induced by large bias currents flowing in a strongly asymmetric supercurrent path. Such a large change in supercurrent path suggests superconducting phase mismatch between the s -wave and chiral p -wave states at the Ru /Sr2RuO4 interface.

  10. Resistive switching and magnetic behavior of Bi0.8Ba0.2FeO3 / SrRuO3 / SrTiO3 films: role of thickness-dependent strain

    NASA Astrophysics Data System (ADS)

    Vagadia, Megha; Ravalia, Ashish; Trivedi, Priyanka; Jethva, Sadaf; Katba, Savan; Kuberkar, D. G.

    2016-05-01

    The thickness-dependent resistive switching and magnetic behavior of Bi0.8Ba0.2FeO3/SRO/STO (1 0 0) films have been studied in the context of strain modifications introduced by varying the film thickness. Generation of misfit dislocation results in strain relaxation with an increase in film thickness. All films (50, 100 and 200 nm) show hysteresis in I–V behavior at room temperature with applied voltage V max  =  ±5 V. Fitting of I–V data suggests that trap-controlled SCLC governs the conduction in HRS in the 50 nm film while in the 100 nm and 200 nm films, the charge transport mechanism is ohmic-type throughout the applied field. The ON/OFF switching ratio and current retention performance decrease with an increase in film thickness, suggesting that substrate-induced strain and interface modifications play an important role in governing the resistive switching mechanism in Bi0.8Ba0.2FeO3 films. A film with lower thickness ~50 nm is found to exhibit the highest magnetization which may be attributed to the increase in oxygen vacancies and compressive strain.

  11. Constitution and thermodynamics of the Mo-Ru, Mo-Pd, Ru-Pd and Mo-Ru-Pd systems

    NASA Astrophysics Data System (ADS)

    Kleykamp, H.

    1989-09-01

    The constitution of the Mo-Ru, Mo-Pd and Ru-Pd systems was reinvestigated between 800 and 2000°C. The Mo-Ru system is of the eutectic type, a σ-phase Mo 5Ru 3 exists between 1915 and 1143°C. The Mo-Pd system is characterized by an hcp phase Mo 9Pd 11 and by two peritectic reactions, β- Mo( Pd) + L = Mo9Pd11andMo9Pd11 + L = α- Pd( Mo). Mo 9Pd 11 decomposes eutectoidally at 1370°C. The Ru-Pd system is simple peritectic. The continuous series of the hcp solid solutions between Mo 9Pd 11 and ɛ-Ru(Mo, Pd) in the ternary Mo-Ru-Pd system observed at 1700°C are suppressed below 1370°C near the Mo-Pd boundary system by the formation of a narrow α + β + ɛ three-phase field. Relative partial molar Gibbs energies of Mo, Mo and Ru in the respective binary systems and of Mo in the ternary system were measured by the EMF method with a Zr(Ca)O 2 electrolyte. xsΔ ḠMo∞ quantities were evaluated at 1200 K which give -43 kJ/mol Mo in Ru and -94 kJ/mol Mo in Pd at infinite dilution. Gibbs energies of formation of the Mo-Ru and Mo-Pd systems were calculated.

  12. Thermoelectric Properties of Pseudogap Ti10Ru19B8 and Ti9TM2Ru18B8 (TM: Cr-Cu) Compounds

    NASA Astrophysics Data System (ADS)

    Takagiwa, Y.; Yoshida, T.; Yanagihara, D.; Kimura, K.

    2015-06-01

    The thermoelectric properties of ternary Ti10Ru19B8 and quaternary Ti9TM2Ru18B8 (TM: Cr, Mn, Fe, Co, Ni, Cu) compounds were investigated in the temperature range from 373 K to 973 K. They form pseudogaps in the electronic densities of states near the Fermi level, E F, which is suitable for thermoelectric materials. We synthesized crack-free pellet samples using arc-melting followed by spark plasma sintering. A maximum dimensionless figure of merit zT max was 0.09 at 973 K for Ti10Ru19B8 whereas a large power factor of 1.4 mW/m K2 was obtained at that temperature. The phonon thermal conductivity decreased through TM substitutions; however, the power factor also decreased due to an additional electronic density of states originated from TM d-states around E F; that is, excitations of both holes and electrons.

  13. Underlayer Effect on Perpendicular Magnetic Anisotropy in Co20Fe60B20\\MgO Films

    PubMed Central

    Chen, P.J.; Iunin, Y.L.; Cheng, S.F.; Shull, R.D.

    2016-01-01

    Perpendicular Magnetic Tunneling Junctions (pMTJs) with Ta\\CoFeB\\MgO have been extensively studied in recent years. However, the effects of the underlayer on the formation of the CoFeB perpendicular magnetic anisotropy (PMA) are still not well understood. Here we report the results of our systematic use of a wide range of elements (Ti, V, Cr, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Os, Ir, Pt and Au) encompassed by columns IVA, VA, VIA, VIIA and VIIIA of the periodic table as the underlayer in a underlayer\\Co20Fe60B20\\MgO stack. Our goals were to survey more elements which could conceivably create a PMA in CoFeB and thereby to explore the mechanisms enabling these underlayers to enhance or create the PMA. We found underlayer elements having both an outer shell of 4d electrons (Zr, Nb Mo, and Pd) and 5d electrons (Hf, Ta, W, Re, Ir, and Pt) resulted in the development of a PMA in the MgO-capped Co20Fe60B20. Hybridization between the 3d electrons of the Fe or Co (in the Co20Fe60B20) at the interface with the 4d or 5d electrons of the underlayer is thought to be the cause of the PMA development. PMID:27499549

  14. Photocatalytic hydrogen production from a simple water-soluble [FeFe]-hydrogenase model system.

    PubMed

    Cao, Wei-Ning; Wang, Feng; Wang, Hong-Yan; Chen, Bin; Feng, Ke; Tung, Chen-Ho; Wu, Li-Zhu

    2012-08-21

    Combined with a simple water soluble [FeFe]-hydrogenase mimic 1, Ru(bpy)(3)(2+) and ascorbic acid enable hydrogen production photocatalytically. More than 88 equivalents of H(2) were achieved in water, which is much better than that obtained in an organic solvent or a mixture of organic solvent and water. PMID:22772838

  15. Electronic correlations, magnetism, and Hund's rule coupling in the ruthenium perovskites SrRuO3 and CaRuO3

    NASA Astrophysics Data System (ADS)

    Dang, Hung T.; Mravlje, Jernej; Georges, Antoine; Millis, Andrew J.

    2015-05-01

    A comparative density functional plus dynamical mean field theory study of the pseudocubic ruthenate materials CaRuO3 and SrRuO3 is presented. Phase diagrams are determined for both materials as a function of Hubbard repulsion U and Hund's rule coupling J . Metallic and insulating phases are found, as are ferromagnetic and paramagnetic states. The locations of the relevant phase boundaries are determined. Based on the computed phase diagrams, Mott dominated and Hund's dominated regimes of strong correlation are distinguished. Comparison of calculated properties to experiments indicates that the actual materials are in the Hund's coupling dominated region of the phase diagram so can be characterized as Hund's metals, in common with other members of the ruthenate family. Comparison of the phase diagrams for the two materials reveals the role played by rotational and tilt (GdFeO3-type) distortions of the ideal perovskite structure. The presence of magnetism in SrRuO3 and its absence in CaRuO3 despite the larger mass and larger tilt/rotational distortion amplitude of CaRuO3 can be understood in terms of density of states effects in the presence of strong Hund's coupling. Comparison of the calculated low-T properties of CaRuO3 to those of SrRuO3 provides insight into the effects of magnetic order on the properties of a Hund's metal. The study provides a simultaneous description of magnetism and correlations and explicates the roles played by band theory and Hubbard and Hund's interactions.

  16. Spectroscopic, Electrochemical and Computational Characterisation of Ru Species Involved in Catalytic Water Oxidation: Evidence for a [Ru(V) (O)(Py2 (Me) tacn)] Intermediate.

    PubMed

    Casadevall, Carla; Codolà, Zoel; Costas, Miquel; Lloret-Fillol, Julio

    2016-07-11

    A new family of ruthenium complexes based on the N-pentadentate ligand Py2 (Me) tacn (N-methyl-N',N''-bis(2-picolyl)-1,4,7-triazacyclononane) has been synthesised and its catalytic activity has been studied in the water-oxidation (WO) reaction. We have used chemical oxidants (ceric ammonium nitrate and NaIO4 ) to generate the WO intermediates [Ru(II) (OH2 )(Py2 (Me) tacn)](2+) , [Ru(III) (OH2 )(Py2 (Me) tacn)](3+) , [Ru(III) (OH)(Py2 (Me) tacn)](2+) and [Ru(IV) (O)(Py2 (Me) tacn)](2+) , which have been characterised spectroscopically. Their relative redox and pH stability in water has been studied by using UV/Vis and NMR spectroscopies, HRMS and spectroelectrochemistry. [Ru(IV) (O)(Py2 (Me) tacn)](2+) has a long half-life (>48 h) in water. The catalytic cycle of WO has been elucidated by using kinetic, spectroscopic, (18) O-labelling and theoretical studies, and the conclusion is that the rate-determining step is a single-site water nucleophilic attack on a metal-oxo species. Moreover, [Ru(IV) (O)(Py2 (Me) tacn)](2+) is proposed to be the resting state under catalytic conditions. By monitoring Ce(IV) consumption, we found that the O2 evolution rate is redox-controlled and independent of the initial concentration of Ce(IV) . Based on these facts, we propose herein that [Ru(IV) (O)(Py2 (Me) tacn)](2+) is oxidised to [Ru(V) (O)(Py2 (Me) tacn)](2+) prior to attack by a water molecule to give [Ru(III) (OOH)(Py2 (Me) tacn)](2+) . Finally, it is shown that the difference in WO reactivity between the homologous iron and ruthenium [M(OH2 )(Py2 (Me) tacn)](2+) (M=Ru, Fe) complexes is due to the difference in the redox stability of the key M(V) (O) intermediate. These results contribute to a better understanding of the WO mechanism and the differences between iron and ruthenium complexes in WO reactions. PMID:27324949

  17. A dinuclear Ni(mu-H)Ru complex derived from H2.

    PubMed

    Ogo, Seiji; Kabe, Ryota; Uehara, Keiji; Kure, Bunsho; Nishimura, Takashi; Menon, Saija C; Harada, Ryosuke; Fukuzumi, Shunichi; Higuchi, Yoshiki; Ohhara, Takashi; Tamada, Taro; Kuroki, Ryota

    2007-04-27

    Models of the active site in [NiFe]hydrogenase enzymes have proven challenging to prepare. We isolated a paramagnetic dinuclear nickel-ruthenium complex with a bridging hydrido ligand from the heterolytic cleavage of H2 by a dinuclear NiRu aqua complex in water under ambient conditions (20 degrees C and 1 atmosphere pressure). The structure of the hexacoordinate Ni(mu-H)Ru complex was unequivocally determined by neutron diffraction analysis, and it comes closest to an effective analog for the core structure of the proposed active form of the enzyme. PMID:17463285

  18. Many metals make the cut: quaternary rare-earth germanides RE4M2InGe4 (M = Fe, Co, Ni, Ru, Rh, Ir) and RE4RhInGe4 derived from excision of slabs in RE2InGe2.

    PubMed

    Oliynyk, Anton O; Stoyko, Stanislav S; Mar, Arthur

    2015-03-16

    The formation of quaternary rare-earth (RE) germanides containing transition metals (M's) from groups 6 to 10 was investigated through arc-melting and annealing reactions at 800 °C; about 50 new compounds were obtained. These include several new series of quaternary germanides RE4M2InGe4 (M = Fe, Co, Ru, Rh, Ir), previously known only for M = Mn and Ni; additional members of RE4Ni2InGe4 extended to other RE substituents; and a different but closely related series RE4RhInGe4. Detailed crystal structures were determined by single-crystal X-ray diffraction studies for 20 compounds. Monoclinic structures in space group C2/m are adopted by RE4M2InGe4 (Ho4Ni2InGe4-type, a = 15.1-16.5 Å, b = 4.1-4.4 Å, c = 6.9-7.3 Å, β = 106.2-108.6°) and RE4RhInGe4 (own type, a = 20.0-20.2 Å, b = 4.2-4.3 Å, c = 10.1-10.2 Å, β = 105.0-105.3°). Both structures contain frameworks built from MGe4 tetrahedra, InGe4 square planes, and Ge2 dimers, delimiting tunnels occupied by RE atoms. These structures can also be derived by cutting slabs along different directions from the more symmetrical RE2InGe2 structure. Although the Ge2 dimers are relatively invariant, the InGe4 square planes can undergo distortion to form two sets of short versus long In-Ge distances. This distortion results from a competition between M-Ge bonding in the MGe4 tetrahedra and In-Ge bonding in the InGe4 square planes. PMID:25731609

  19. Pressure Induced Enhancement of Superconductivity in LaRu2P2

    PubMed Central

    Li, Baoxuan; Liu, Jianzhong; Sun, Jian; Li, Sheng; Zhu, Xiyu; Wen, Hai-Hu

    2016-01-01

    To explore new superconductors beyond the copper-based and iron-based systems is very important. The Ru element locates just below the Fe in the periodic table and behaves like the Fe in many ways. One of the common thread to induce high temperature superconductivity is to introduce moderate correlation into the system. In this paper, we report the significant enhancement of superconducting transition temperature from 3.8 K to 5.8 K by using a pressure only of 1.74 ± 0.05 GPa in LaRu2P2 which has an iso-structure of the iron-based 122 superconductors. The ab-initio calculation shows that the superconductivity in LaRu2P2 at ambient pressure can be explained by the McMillan’s theory with strong electron-phonon coupling. However, it is difficult to interpret the enhancement of Tc versus pressure within this picture. Detailed analysis of the pressure induced evolution of resistivity and upper critical field Hc2(T) reveals that the increase of Tc with pressure may be accompanied by the involvement of extra electron-boson interaction. This suggests that the Ru-based system has some commonality as the Fe-based superconductors. PMID:27086696

  20. Pressure Induced Enhancement of Superconductivity in LaRu2P2

    NASA Astrophysics Data System (ADS)

    Li, Baoxuan; Lu, Pengchao; Liu, Jianzhong; Sun, Jian; Li, Sheng; Zhu, Xiyu; Wen, Hai-Hu

    2016-04-01

    To explore new superconductors beyond the copper-based and iron-based systems is very important. The Ru element locates just below the Fe in the periodic table and behaves like the Fe in many ways. One of the common thread to induce high temperature superconductivity is to introduce moderate correlation into the system. In this paper, we report the significant enhancement of superconducting transition temperature from 3.8 K to 5.8 K by using a pressure only of 1.74 ± 0.05 GPa in LaRu2P2 which has an iso-structure of the iron-based 122 superconductors. The ab-initio calculation shows that the superconductivity in LaRu2P2 at ambient pressure can be explained by the McMillan’s theory with strong electron-phonon coupling. However, it is difficult to interpret the enhancement of Tc versus pressure within this picture. Detailed analysis of the pressure induced evolution of resistivity and upper critical field Hc2(T) reveals that the increase of Tc with pressure may be accompanied by the involvement of extra electron-boson interaction. This suggests that the Ru-based system has some commonality as the Fe-based superconductors.

  1. Pressure Induced Enhancement of Superconductivity in LaRu2P2.

    PubMed

    Li, Baoxuan; Lu, Pengchao; Liu, Jianzhong; Sun, Jian; Li, Sheng; Zhu, Xiyu; Wen, Hai-Hu

    2016-01-01

    To explore new superconductors beyond the copper-based and iron-based systems is very important. The Ru element locates just below the Fe in the periodic table and behaves like the Fe in many ways. One of the common thread to induce high temperature superconductivity is to introduce moderate correlation into the system. In this paper, we report the significant enhancement of superconducting transition temperature from 3.8 K to 5.8 K by using a pressure only of 1.74 ± 0.05 GPa in LaRu2P2 which has an iso-structure of the iron-based 122 superconductors. The ab-initio calculation shows that the superconductivity in LaRu2P2 at ambient pressure can be explained by the McMillan's theory with strong electron-phonon coupling. However, it is difficult to interpret the enhancement of Tc versus pressure within this picture. Detailed analysis of the pressure induced evolution of resistivity and upper critical field Hc2(T) reveals that the increase of Tc with pressure may be accompanied by the involvement of extra electron-boson interaction. This suggests that the Ru-based system has some commonality as the Fe-based superconductors. PMID:27086696

  2. In situ facile synthesis of Ru-based core-shell nanoparticles supported on carbon black and their high catalytic activity in the dehydrogenation of amine-boranes.

    PubMed

    Cao, Nan; Su, Jun; Hong, Xinlin; Luo, Wei; Cheng, Gongzhen

    2014-02-01

    Well-dispersed core-shell Ru@M (M=Co, Ni, Fe) nanoparticles (NPs) supported on carbon black have been synthesized via a facile in situ one-step procedure under ambient condition. Core-shell Ru@Co NPs were synthesized and characterized for the first time. The as-synthesized Ru@Co and Ru@Ni NPs exhibit superior catalytic activity in the hydrolysis of ammonia borane compared with their monometallic and alloy counterparts. The Ru@Co/C NPs are the most reactive, with a turnover frequency (TOF) value of 320 (mol H 2 min(-1)) molRu (-1) and activation energy (Ea) of 21.16 kJ mol(-1). Ru@Ni/C NPs are the next most active, whereas Ru@Fe/C NPs are almost inactive. Additionally, the as-synthesized NPs supported on carbon black exhibit higher catalytic activity than catalysts on other conventional supports, such as SiO2 and γ-Al2O3. PMID:24288206

  3. Photoinduced Charge Separation within Metallo-supramolecular Wires Built around a [Ru(bpy)3](2+)-Bisterpyridine Linear Entity.

    PubMed

    Farran, Rajaa; Jouvenot, Damien; Gennaro, Béatrice; Loiseau, Frédérique; Chauvin, Jérôme; Deronzier, Alain

    2016-06-29

    A [Ru(bpy)3](2+)-like complex (L1) bearing two free terpyridine groups at the 5 and 5' positions of the same bipyridine, linked by the rigid and linear 2,5-dimethyl phenylene bridges has been synthesized to open access to two classes of linear molecular wires with photosensitive properties: a bimetallic coordination polymer and an inorganic triad. In this Research Article, we report on the synthesis and characterization of the resulting [{Ru(II_)Fe(II)}n](4n+) alternated bimetallic polymer and the [Co(III_)Ru(II_)Fe(II)](7+) triad based on the building block L1. The [{Ru(II_)Fe(II)}n](4n+) polymer is fully characterized in solution. Cyclic voltammetry and emission lifetime measurements show that the bridging ligand allows interaction between the metal centers in the excited state despite the lack of interactions in the ground state. Under visible irradiation, the polymer can be fully oxidized in the presence of a sacrificial electron acceptor in solution. Thin robust films of the polymer are easily obtained on ITO by a simple electrochemical procedure based on an electroreduction adsorption process. The ITO/[{Ru(II_)Fe(II)}n](4n+)-modified electrode behaves as a photocathode under irradiation in the presence of ArN2(+). The magnitude of the photocurrent is dependent on the film thickness, probably limited by the diffusion of charge in thicker film. On the other hand L1 is also used to construct a well-ordered triad in association with Co(III) and Fe(II) metallic centers as electron acceptor and donor, respectively. The metallic triad is anchored on ITO or on a SiO2 wafer, starting from a terpyridine phosphonate modified surface. AFM images prove the presence of the triad in a linear upward orientation. Irradiation of the ITO/[Co(III_)Ru(II_)Fe(II)](7+) modified surface in the presence of triethanolamine in CH3CN induces the generation of an anodic photocurrent of around 30 μA.cm(-2). The photocurrent density generated by the ITO/[Co(III_)Ru(II_)Fe(II)](7

  4. Guided ion beam and theoretical study of the reactions of Os{sup +} with H{sub 2}, D{sub 2}, and HD

    SciTech Connect

    Hinton, Christopher S.; Citir, Murat; Armentrout, P. B.

    2011-12-21

    Reactions of the third-row transition metal cation Os{sup +} with H{sub 2}, D{sub 2}, and HD to form OsH{sup +} (OsD{sup +}) were studied using a guided ion beam tandem mass spectrometer. A flow tube ion source produces Os{sup +} in its {sup 6}D (6s{sup 1}5d{sup 6}) electronic ground state level. Corresponding state-specific reaction cross sections are obtained. The kinetic energy dependences of the cross sections for the endothermic formation of OsH{sup +} and OsD{sup +} are analyzed to give a 0 K bond dissociation energy of D{sub 0}(Os{sup +}-H) = 2.45 {+-} 0.10 eV. Quantum chemical calculations are performed here at several levels of theory, with B3LYP approaches generally overestimating the experimental bond energy whereas results obtained using BHLYP and CCSD(T), coupled-cluster with single, double, and perturbative triple excitations, levels show good agreement. Theory also provides the electronic structures of these species and the potential energy surfaces for reaction. Results from the reactions with HD provide insight into the reaction mechanism and indicate that Os{sup +} reacts via a direct reaction. We also compare this third-row transition metal system with the first-row and second-row congeners, Fe{sup +} and Ru{sup +}, and find that Os{sup +} reacts more efficiently with dihydrogen, forming a stronger M{sup +}-H bond. These differences can be attributed to the lanthanide contraction and relativistic effects.

  5. Suppression of ferromagnetism and observation of quantum well states in epitaxial thin films of the cubic ruthenate BaRuO3

    NASA Astrophysics Data System (ADS)

    Burganov, Bulat; Paik, Hanjong; Shen, Kyle; Schlom, Darrell

    The pseudocubic perovskite ruthenates ARuO3, where A is alkaline earth metal, are correlated materials where Hund's coupling drives correlations and leads to a low coherence scale, large renormalization, and formation of local moments. The ferromagnetic BaRuO3 has an ideal cubic structure and a larger bandwidth, compared to its GdFeO3-distorted counterparts, CaRuO3 and SrRuO3. In stark contrast to SrRuO3, which is a Fermi liquid below TC, BaRuO3 exhibits critical fluctuations near TC that are enhanced under hydrostatic pressure, which suppresses the Fermi liquid coherence scale and TC and drives a crossover into non-FL regime. Here we use ARPES to characterize the momentum-resolved electronic structure of strained ultrathin BaRuO3 films grown in situ by molecular beam epitaxy. The films on STO (001) are metallic down to 2 u.c. thickness and manifest clearly defined subbands of well-defined quasiparticles which arise due to quantum confinement effects. We observe that the bands are moderately renormalized compared to bare GGA bands and discover that the ferromagnetism can be suppressed in the atomically thin limit. We discuss our results on BaRuO3 in the context of our recent ARPES studies of the other perovskite ruthenates, SrRuO3 and CaRuO3.

  6. Theoretical calculations for structural, elastic, and thermodynamic properties of RuN{sub 2} under high pressure

    SciTech Connect

    Dong, Bing; Zhou, Xiao-Lin E-mail: lkworld@126.com; Chang, Jing; Liu, Ke E-mail: lkworld@126.com

    2014-08-07

    The structural and elastic properties of RuN{sub 2} were investigated through the first-principles calculation using generalized gradient approximation (GGA) and local density approximation (LDA) within the plane-wave pseudopotential density functional theory. The obtained equilibrium structure and mechanical properties are in excellent agreement with other theoretical results. Then we compared the elastic modulus of RuN{sub 2} with several other isomorphic noble metal nitrides. Results show that RuN{sub 2} can nearly rival with OsN{sub 2} and IrN{sub 2}, which indicate RuN{sub 2} is a potentially ultra-incompressible and hard material. By the elastic stability criteria, it is predicted that RuN{sub 2} is stable in our calculations (0–100 GPa). The calculated B/G ratios indicate that RuN{sub 2} possesses brittle nature at 0 GPa and when the pressure increases to 13.4 GPa (for LDA) or 20.8 GPa (for GGA), it begins to prone to ductility. Through the quasi-harmonic Debye model, we also investigated the thermodynamic properties of RuN{sub 2}.

  7. Atomistic Modeling of RuAl and (RuNi) Al Alloys

    NASA Technical Reports Server (NTRS)

    Gargano, Pablo; Mosca, Hugo; Bozzolo, Guillermo; Noebe, Ronald D.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Atomistic modeling of RuAl and RuAlNi alloys, using the BFS (Bozzolo-Ferrante-Smith) method for alloys is performed. The lattice parameter and energy of formation of B2 RuAl as a function of stoichiometry and the lattice parameter of (Ru(sub 50-x)Ni(sub x)Al(sub 50)) alloys as a function of Ni concentration are computed. BFS based Monte Carlo simulations indicate that compositions close to Ru25Ni25Al50 are single phase with no obvious evidence of a miscibility gap and separation of the individual B2 phases.

  8. Chemistry and petrology of Fe-Ni beads from different types of cosmic spherules: Implication for precursors

    NASA Astrophysics Data System (ADS)

    Rudraswami, N. G.; Prasad, M. Shyam; Babu, E. V. S. S. K.; Kumar, T. Vijaya

    2014-11-01

    Fe-Ni beads are observed to occur in all three (Stony, Glass, Iron) types of cosmic spherules collected from deep sea sediments of the Indian Ocean. Fe-Ni beads in cosmic spherules can provide insights for understanding metal segregation mechanisms and their refractory metal element (RME: Re, Os, W, Ir, Ru, Mo, Pt, Rh including Pd) compositions can help ascertain their precursor meteorites. We measured RME compositions of 55 Fe-Ni beads using LA-ICP-MS in all three basic types of cosmic spherules selected after examining ∼2000 cosmic spherules. The RMEs of Fe-Ni beads provide unique information on formation and differentiation during atmospheric entry. The variability in the concentration of the RMEs depends on the initial mass of the cosmic spherules, volatility, temperature attained and efficiency in metal segregation during entry. The CI chondrite and Os normalized RME compositions of the beads display a pattern that is close to CI chondritic composition. The presence of Pd, a non-refractory metal having condensation temperature similar to Fe, in Fe-Ni beads of all types of cosmic spherules indicates that the heating undergone was below its vaporization temperature. Not all parent bodies lead to the formation of beads, the precursor needs to exceed a certain minimum size and temperature to facilitate the metal to get segregated into beads. The minimum size of a parent particle that could enclose a Fe-Ni bead is estimated to have a size ∼1 mm. This places constraints on the sizes of materials that are ablated during entry, and the accompanying mass loss during entry. Our study further points out that all the three basic types of cosmic spherules have a chondritic origin based on their RME distribution patterns. Only metal-rich carbonaceous chondrites contain the required quantities of metal for the formation of Fe-Ni beads during atmospheric entry and during this process the RMEs are also efficiently segregated into these beads.

  9. Arrays of Ru Nanoclusters with Narrow Size Distribution Templated by Monolayer Graphene on Ru

    SciTech Connect

    Sutter, P.; Sutter, E.; Albrecht, P.; Wang, B.; Bocquet M.-L.; Wu, L.; Zhu, Y.

    2011-09-01

    Ru nanoclusters self-assemble over macroscopic sample areas during vapor deposition of Ru on monolayer graphene (MLG) on Ru(0001). The Ru nanoclusters form arrays with a mean lateral cluster diameter of {approx} 20 {angstrom}, cluster heights of 1 or 2 ML, and a size distribution that remains nearly constant with increasing coverage. Combined scanning tunneling microscopy and density functional theory (DFT) show that the clusters are templated by the MLG/Ru(0001) moire unit cell and identify the preferred binding site of the clusters as the low fcc region of the moire. Cross-sectional transmission electron microscopy (TEM) and high-resolution TEM contrast simulations experimentally demonstrate that the interaction of the Ru clusters with the underlying MLG/Ru(0001) leads to a local lifting of the graphene layer of the template. DFT calculations confirm this mechanism of interaction of the Ru clusters with the strongly coupled MLG/Ru(0001). Weakening of the graphene-support coupling via oxygen intercalation is shown to have a major effect on the assembly of Ru nanocluster arrays. With a preferred binding site lacking on decoupled graphene, the Ru nanoclusters grow significantly larger, and clusters with 1 to 4 ML height can coexist.

  10. Interpenetrating Diruthenium Tetraformate Monocation, [RuII/III2(O2CH)4]+, Based 3-D Molecule-based Magnets

    SciTech Connect

    Kennon, B.; Stone, K; Stephens, P; Miller, J

    2009-01-01

    Synthesis of [Ru{sub 2}(O{sub 2}CH){sub 4}]{sub 3}[MIII(CN){sub 6}] (M = Co, Fe) possessing an interpenetrating body center cubic (bcc) lattices was investigated utilizing several synthetic methods. The targeted interpenetrating bcc [a = 12.6621(3) {angstrom}] structure was obtained for [Ru{sub 2}(O{sub 2}CH){sub 4}]{sub 3}[Co(CN){sub 6}], and it exhibits {chi}T(T) that is fit to a model which includes zero field splitting. Cyanide abstraction from [Cr(CN){sub 6}]{sup 3-} occurs thwarting the formation of [Ru{sub 2}(O{sub 2}CH){sub 4}]{sub 3}[M(CN){sub 6}]. [Ru{sub 2}(O{sub 2}CH){sub 4}]{sub 3}[Fe(CN){sub 6}] also exhibits the desired bcc structure [12.7071(3) {angstrom}], and its 13.4 K T{sub c} is a 6-fold enhancement with respect to that observed for [Ru{sub 2}(O{sub 2}CMe){sub 4}]{sub 3}[Fe(CN){sub 6}].

  11. Ferromagnetic CaRuO3

    PubMed Central

    Tripathi, Shivendra; Rana, Rakesh; Kumar, Sanjay; Pandey, Parul; Singh, R. S.; Rana, D. S.

    2014-01-01

    The non-magnetic and non-Fermi-liquid CaRuO3 is the iso-structural analog of the ferromagnetic (FM) and Fermi-liquid SrRuO3. We show that an FM order in the orthorhombic CaRuO3 can be established by the means of tensile epitaxial strain. The structural and magnetic property correlations in the CaRuO3 films formed on SrTiO3 (100) substrate establish a scaling relation between the FM moment and the tensile strain. The strain dependent crossover from non-magnetic to FM CaRuO3 was observed to be associated with switching of non-Fermi liquid to Fermi-liquid behavior. The intrinsic nature of this strain-induced FM order manifests in the Hall resistivity too; the anomalous Hall component realizes in FM tensile-strained CaRuO3 films on SrTiO3 (100) whereas the non-magnetic compressive-strained films on LaAlO3 (100) exhibit only the ordinary Hall effect. These observations of an elusive FM order are consistent with the theoretical predictions of scaling of the tensile epitaxial strain and the magnetic order in tensile CaRuO3. We further establish that the tensile strain is more efficient than the chemical route to induce FM order in CaRuO3. PMID:24464302

  12. Nanosecond photoreduction of cytochrome p450cam by channel-specific Ru-diimine electron tunneling wires.

    PubMed

    Dunn, Alexander R; Dmochowski, Ivan J; Winkler, Jay R; Gray, Harry B

    2003-10-15

    We report the synthesis and characterization of Ru-diimine complexes designed to bind to cytochrome p450cam (CYP101). The sensitizer core has the structure [Ru(L(2))L'](2+), where L' is a perfluorinated biphenyl bridge (F(8)bp) connecting 4,4'-dimethylbipyridine to an enzyme substrate (adamantane, F(8)bp-Ad), a heme ligand (imidazole, F(8)bp-Im), or F (F(9)bp). The electron-transfer (ET) driving force (-deltaG degrees ) is varied by replacing the ancillary 2,2'-bipyridine ligands with 4,4',5,5'-tetramethylbipyridine (tmRu). The four complexes all bind p450cam tightly: Ru-F(8)bp-Ad (1, K(d) = 0.077 microM); Ru-F(8)bp-Im (2, K(d) = 3.7 microM); tmRu-F(9)bp (3, K(d) = 2.1 microM); and tmRu-F(8)bp-Im (4, K(d) = 0.48 microM). Binding is predominantly driven by hydrophobic interactions between the Ru-diimine wires and the substrate access channel. With Ru-F(8)bp wires, redox reactions can be triggered on the nanosecond time scale. Ru-wire 2, which ligates the heme iron, shows a small amount of transient heme photoreduction (ca. 30%), whereas the transient photoreduction yield for 4 is 76%. Forward ET with 4 occurs in roughly 40 ns (k(f) = 2.8 x 10(7) s(-)(1)), and back ET (Fe(II) --> Ru(III), k(b) approximately 1.7 x 10(8) s(-)(1)) is near the coupling-limited rate (k(max)). Direct photoreduction was not observed for 1 or 3. The large variation in ET rates among the Ru-diimine:p450 conjugates strongly supports a through-bond model of Ru-heme electronic coupling. PMID:14531688

  13. Model study of CO inhibition of [NiFe]hydrogenase.

    PubMed

    Matsumoto, Takahiro; Kabe, Ryota; Nonaka, Kyoshiro; Ando, Tatsuya; Yoon, Ki-Seok; Nakai, Hidetaka; Ogo, Seiji

    2011-09-19

    We propose a modified mechanism for the inhibition of [NiFe]hydrogenase ([NiFe]H(2)ase) by CO. We present a model study, using a NiRu H(2)ase mimic, that demonstrates that (i) CO completely inhibits the catalytic cycle of the model compound, (ii) CO prefers to coordinate to the Ru(II) center rather than taking an axial position on the Ni(II) center, and (iii) CO is unable to displace a hydrido ligand from the NiRu center. We combine these studies with a reevaluation of previous studies to propose that, under normal circumstances, CO inhibits [NiFe]H(2)ase by complexing to the Fe(II) center. PMID:21853978

  14. First identification of excited states in the N=Z+1 nucleus {sup 89}Ru

    SciTech Connect

    Marginean, N.; Rusu, C.; Bucurescu, D.; Ionescu-Bujor, M.; Iordachescu, A.; Alvarez, C. Rossi; Bazzacco, D.; Lunardi, S.; Pavan, P.; Farnea, E.; Lenzi, S.M.; Menegazzo, R.; Ur, C.A.; De Angelis, G.; Axiotis, M.; Gadea, A.; Kroell, Th.; Martinez, T.; Napoli, D.R.; Spolaore, P.

    2004-10-01

    High-spin excited states have been identified for the first time in the N=Z+1 nucleus {sup 89}Ru with the reaction {sup 54}Fe({sup 40}Ca,{alpha}n{gamma}) at 130 MeV, using the GASP array, the ISIS Silicon array, and the n-Ring detector system. The observed structure is discussed within systematics of the N=45 isotones and is compared with shell model calculations.

  15. Vacuolar membrane transporters OsVIT1 and OsVIT2 modulate iron translocation between flag leaves and seeds in rice.

    PubMed

    Zhang, Yu; Xu, Yong-Han; Yi, Hong-Yin; Gong, Ji-Ming

    2012-11-01

    The plant vacuole is an important organelle for storing excess iron (Fe), though its contribution to increasing the Fe content in staple foods remains largely unexplored. In this study we report the isolation and functional characterization of two rice genes OsVIT1 and OsVIT2, orthologs of the Arabidopsis VIT1. Transient expression of OsVIT1:EGFP and OsVIT2:EGFP protein fusions revealed that OsVIT1 and OsVIT2 are localized to the vacuolar membrane. Ectopic expression of OsVIT1 and OsVIT2 partially rescued the Fe(2+) - and Zn(2+) -sensitive phenotypes in yeast mutant Δccc1 and Δzrc1, and further increased vacuolar Fe(2+) , Zn(2+) and Mn(2+) accumulation. These data together suggest that OsVIT1 and OsVIT2 function to transport Fe(2+) , Zn(2+) and Mn(2+) across the tonoplast into vacuoles in yeast. In rice, OsVIT1 and OsVIT2 are highly expressed in flag leaf blade and sheath, respectively, and in contrast to OsVIT1, OsVIT2 is highly responsive to Fe treatments. Interestingly, functional disruption of OsVIT1 and OsVIT2 leads to increased Fe/Zn accumulation in rice seeds and a corresponding decrease in the source organ flag leaves, indicating an enhanced Fe/Zn translocation between source and sink organs, which might represent a novel strategy to biofortify Fe/Zn in staple foods. PMID:22731699

  16. Ru(4+) induced colossal magnetoimpedance in Ru doped perovskite manganite at room temperature.

    PubMed

    Singh, Brajendra

    2016-05-14

    We have demonstrated Ru(4+) induced colossal magnetoimpedance (MI) at room temperature in a ∼1 Tesla magnetic field with a pulsed laser deposited La0.7Ca0.3Mn0.7Ru0.3O3 thin film. This composition showed a large negative ∼12% MI in the low frequency range (<5 MHz), a colossal positive MI > 120% in the intermediate frequency range (5 MHz to ∼13 MHz) and a negative MI in the high frequency range (∼13 MHz to 40 MHz) at room temperature. XAS data confirmed the predominant Ru valence state was 4+ in La0.7Ca0.3Mn0.7Ru0.3O3. Ru(4+) induced (i) charge carrier localization and (ii) reduced hole carrier density enhances the MI in this composition, which otherwise was not significant in mixed valences Mn(3+)/Mn(4+) containing La0.7Ca0.3MnO3 and Ru(4+)/Ru(5+) and Mn(3+)/Mn(4+) mixed valences containing Ru = 0.1 and Ru = 0.2 compositions in La0.7Ca0.3Mn1-xRuxO3 (0 ≤x≤ 0.3) thin films. PMID:27109569

  17. First water-soluble backbone Ru-Ru-Ni heterometallic organometallic polymer.

    PubMed

    Scalambra, Franco; Serrano-Ruiz, Manuel; Romerosa, Antonio

    2015-04-01

    The water-soluble backbone heterometallic polymer {[(PTA)2 CpRu-μ-CN-RuCp(PTA)2 -μ-NiCl3 ]}n (2) is synthesized using a reproducible and robust method and fully characterized by X-ray single crystal diffraction. The Ru-Ru-Ni polymer is found to be stable in the solid state and soluble in water. Nuclear magnetic resonance (NMR) and light scattering studies show that the polymer is stable in water for several days in air. PMID:25739739

  18. Electronic and magnetic properties of SrRuO3 with Ru-vacancy: First-principle calculations

    NASA Astrophysics Data System (ADS)

    Lv, Kai; Zhu, H. P.; Peng, J.; Zhang, G. P.; Wu, X. S.

    2016-01-01

    By using first-principle calculations, the electronic and magnetic properties of the Ru-deficient SrRu1-x O3 (x = 1/32) have been investigated. The obtained results indicate that nearest Ru and O ions of the vacancy move away from the Ru-vacancy, while the nearest Sr ions shift toward the vacancy. Interestingly, an antiferromagnetic spin cluster is formed in the vicinity of the Ru-deficient site. This, in turn, gives rise to reduced overall magnetic moment which better agrees with the experiment values for SrRuO3 reported in the literature. The adjustment of O ions surrounding the vacancy splits the near-vacancy Ru t 2g orbitals, and the unoccupied ones appear above the Fermi level. The truncated effect at the vacancy, modified Ru-O covalent bonds, and Ru-O-Ru angles have jointly stabilized the antiferromagnetic spin cluster.

  19. Fabrication of perpendicular magnetic recording tape media with a data capacity of over-50TB using Si/NiFe/FeCoB soft magnetic underlayers

    NASA Astrophysics Data System (ADS)

    Gomi, S.; Mashiko, Y.; Hirata, K.; Matsunuma, S.; Inoue, T.; Doi, T.; Watanabe, T.; Nakagawa, S.

    C-axis orientations of Ru intermediate layer (IML) and CoPtCr-SiO2 recording layer (RL) are attained by using crystalline FeCoB soft magnetic underlayer (SUL). Better (110) orientation of FeCo improves not only (001) orientation of Ru IML but also that of CoPtCr RL. This leads better perpendicular magnetic anisotropy in the RL suitable for perpendicular magnetic recording media. In order to control the (110) orientation in FeCoB layer, various seed layers are prepared beneath the FeCoB layers. Ru and Si/NiFe seed layers gives FeCoB layer a large in-plane magnetic anisotropy that is effective to suppress spike noise from SUL. The laminated FeCoB SUL causes more improvement of Ru (001) texure and leads to better perpendicular magnetic anisotropy of RL. Ru/CoPtCr-SiO2 bilayer deposited on laminated FeCoB SUL on Aramid tape substrate has good perpendicular magnetic properties and reduces the noise from SUL. PACS: Type pacs here, separated by semicolons;

  20. [Analgesic properties of morpholinoethylimidazobenzimidazole derivative RU-1205].

    PubMed

    Spasov, A A; Grechko, O Iu; Shtareva, D M; Anisimova, V A

    2013-01-01

    We have studied the analgesic activity of a morpholinoethylimidazobenzimidazole derivative (RU-1205) in comparison to butorphanol. It is established that the test compound exhibits a pronounced analgesic activity, which exceeded that ofbutorphanol six times in the hot-plate test and was comparable to the reference drug effect in the tail-flick and acetic acid-induced writhing tests. It is established that the analgesic action of RU-1205 is based on the kappa-opioidergic mechanism. PMID:24432563

  1. Into the Modelling of RU Vir

    NASA Astrophysics Data System (ADS)

    Rau, G.; Hron, J.; Paladini, C.; Eriksson, K.; Aringer, B.; Groenewegen, M. A. T.; Mečina, M.

    2015-08-01

    We present an attempt to model the atmosphere of the carbon-rich Mira star RU Vir, using different techniques including spectroscopy, photometry, and interferometry. A radiative transfer code and hydrostatic model atmospheres were used for a preliminary study. To investigate the dynamic processes happening in RU Vir, dynamic model atmospheres were compared to new MIDI/VLTI observations obtained in April 2014, and SiC opacities were added.

  2. Human Glucocorticoid Receptor β Binds RU-486 and Is Transcriptionally Active▿

    PubMed Central

    Lewis-Tuffin, Laura J.; Jewell, Christine M.; Bienstock, Rachelle J.; Collins, Jennifer B.; Cidlowski, John A.

    2007-01-01

    Human glucocorticoid receptor (hGR) is expressed as two alternately spliced C-terminal isoforms, α and β. In contrast to the canonical hGRα, hGRβ is a nucleus-localized orphan receptor thought not to bind ligand and not to affect gene transcription other than by acting as a dominant negative to hGRα. Here we used confocal microscopy to examine the cellular localization of transiently expressed fluorescent protein-tagged hGRβ in COS-1 and U-2 OS cells. Surprisingly, yellow fluorescent protein (YFP)-hGRβ was predominantly located in the cytoplasm and translocated to the nucleus following application of the glucocorticoid antagonist RU-486. This effect of RU-486 was confirmed with transiently expressed wild-type hGRβ. Confocal microscopy of coexpressed YFP-hGRβ and cyan fluorescent protein-hGRα in COS-1 cells indicated that the receptors move into the nucleus independently. Using a ligand binding assay, we confirmed that hGRβ bound RU-486 but not the hGRα ligand dexamethasone. Examination of the cellular localization of YFP-hGRβ in response to a series of 57 related compounds indicated that RU-486 is thus far the only identified ligand that interacts with hGRβ. The selective interaction of RU-486 with hGRβ was also supported by molecular modeling and computational docking studies. Interestingly, microarray analysis indicates that hGRβ, expressed in the absence of hGRα, can regulate gene expression and furthermore that occupation of hGRβ with the antagonist RU-486 diminishes that capacity despite the lack of helix 12 in the ligand binding domain. PMID:17242213

  3. Platinum-group minerals from placers related to the Nizhni Tagil (Middle Urals, Russia) Uralian-Alaskan-type ultramafic complex: ore-mineralogy and study of silicate inclusions in (Pt, Fe) alloys

    NASA Astrophysics Data System (ADS)

    Johan, Z.

    2006-05-01

    The study of platinum-group minerals (PGM) concentrates from the Nizhni Tagil placers related to the Soloviev Mountain (Gora Solovieva) Uralian-Alaskan-type intrusion revealed a predominance of (Pt, Fe) alloys over Ir-, and Os-bearing alloys. (Pt, Fe) alloys (“isoferroplatinum-type”) are interstitial with respect to chromite and show important variations in their chemical compositions, which are, however, falling within the experimentally determined stability field of isoferroplatinum. Tetraferroplatinum, enriched in Cu and Ni and tulameenite represent low-temperature mineral phases replacing (Pt, Fe) alloys. Alloys belonging to the Os-Ir-Ru ternary system have compositions corresponding to native osmium, iridium and ruthenium, respectively, and to rutheniridosmine. Osmium exsolutions appear in Ir-, and (Pt, Fe) alloys, and iridium exsolutions in (Pt, Fe) alloys. Laurite is a high-temperature phase included in native iridium and (Pt, Fe) alloys. Low-temperature PGM association comprises Ir-bearing sulpharsenides, including a phase (Ir, Os, Fe, Pt, Ru, Ni)3(As, Sb)0.85S, and a palladium antimonide Pd20Sb7. These two phases were previously unknown in nature. Furthermore, native palladium occurs in the studied concentrates. This low-temperature paragenesis indicates an interaction of Pt-, Os-, Ir- and Ru-bearing alloys with late fluids enriched in volatiles, As and Sb. The chromite composition is characterized by the predominance of Cr3+ → Fe3+ substitution like in other Uralian-Alaskan-type intrusions; that indicates a fO2 variation during the chromite precipitation. Monomineralic inclusions of euhedral clinopyroxene and chromite crystals in (Pt, Fe) alloys were observed. Furthermore, (Pt, Fe) alloys contain polyphase silicate inclusions, which occupy the alloy negative crystals. Two types of silicate inclusions were recognized: (1) Low-pressure inclusions composed of amphibole, biotite, Jd-poor clinopyroxene, magnetite, apatite and glass; (2) High

  4. Behavior of Ru surfaces after ozonated water treatment

    NASA Astrophysics Data System (ADS)

    Seo, Dongwan; Park, Chanhyoung; Jung, Juneui; Yoon, Mihyun; Lee, Dongwook; Kim, Chang Yeol; Lim, Sangwoo

    2011-10-01

    In order for the development of cleaning technology of extreme ultra violet lithography photomask, the behavior of Ru surfaces after treatment with ozonated deionized water (DIO 3) solution was studied using Ru and ruthenium oxide particles and 2 nm-thick Ru capping layers. No significant changes in crystalline structures or chemical states of the Ru surfaces, nor any similarities with the structures or states of ruthenium oxide, were observed after DIO 3 treatment. Oxidation of ruthenium to form RuO 2 or RuO 3 was not observed. Adsorption of H 2O molecules on the Ru layer increased the surface roughness, but the desorption of H 2O molecules recovered it. Local chemisorption of H 2O molecules on the Ru surface may be the reason why rougher Ru surfaces were observed after DIO 3 cleaning.

  5. Enhanced interlayer exchange coupling in antiferromagnetically coupled ultrathin (Co70Fe30/Pd) multilayers

    NASA Astrophysics Data System (ADS)

    Meng, Zhaoliang; Qiu, Jinjun; Han, Guchang; Teo, Kie Leong

    2015-12-01

    We report the studies of magnetization reversal and magnetic interlayer coupling in synthetic antiferromagnetic (SAF) [Pd/Co70Fe30]9/Ru(tRu)/Pd(tPd)/[Co70Fe30/Pd]9 structure as functions of inserted Pd layer (tPd) and Ru layer (tRu) thicknesses. We found the exchange coupling field (Hex) and perpendicular magnetic anisotropy (PMA) can be controlled by both the tPd and tRu, The Hex shows a Ruderman-Kittel-Kasuya-Yosida-type oscillatory decay dependence on tRu and a maximum interlayer coupling strength Jex = 0.522 erg/cm2 is achieved at tPd + tRu ≈ 0.8 nm in the as-deposited sample. As it is known that a high post-annealing stability of SAF structure is required for magnetic random access memory applications, the dependence of Hex and PMA on the post-annealing temperature (Ta) is also investigated. We found that both high PMA of the top Co70Fe30/Pd multilayer is maintained and Hex is enhanced with increasing Ta up to 350 °C for tRu > 0.7 nm in our SAF structure.

  6. Site segregation in model clusters of small bimetallic RuGe and RuSn aggregates

    SciTech Connect

    Goursot, A.; Pedocchi, L.; Coq, B.

    1994-09-01

    RuGe and RuSn model clusters in both fixed bulk and relaxed structures are studied for stability during relaxation. Distortion causes a reduction in coordination of the Sn or Ge atom. Relaxation causes the Ge to have a small preference for the corner site (low coordination), but the Sn has a large corner site preference. 45 refs., 1 fig., 4 tabs.

  7. Effect of laminated crystalline FeCoB soft magnetic underlayer for perpendicular magnetic recording tape media

    NASA Astrophysics Data System (ADS)

    Gomi, Shunsuke; Mashiko, Yasuhiro; Hirata, Ken-ichiro; Matsunuma, Satoshi; Inoue, Tetsutaro; Doi, Tsugihiro; Watanabe, Toshiyuki; Nakagawa, Shigeki

    2011-04-01

    A crystalline FeCoB soft magnetic underlayer (SUL) improves c-axis orientations of the Ru intermediate layer (IML) and the CoPtCr-SiO2 recording layer (RL). (001) orientations of Ru IML and CoPtCr RL are attained by (110) oriented texture of FeCoB SUL. Since good c-axis orientation in CoPtCr-SiO2 RL as well as domain control in the FeCoB SUL is required for high recording density, a laminated FeCoB SUL is prepared as an underlayer of the bilayered Ru/CoPtCr-SiO2 films. A laminated FeCoB SUL results in better (001) orientation in both CoPtCr-SiO2 RL and Ru IML than the single layered FeCoB SUL. This leads to the reduction of media noise in the high recording frequency region. Recording medium layers composed of a laminated FeCoB SUL and bilayered Ru/CoPtCr-SiO2 films deposited on a 4.5-μm-thick Aramid tape show better (001) orientations of Ru and CoPtCr. Media noise of the tape medium with the laminated SUL is lower than that with the single layered FeCoB SUL.

  8. Ru(0) and Ru(II) nitrosyl pincer complexes: structure, reactivity, and catalytic activity.

    PubMed

    Fogler, Eran; Iron, Mark A; Zhang, Jing; Ben-David, Yehoshoa; Diskin-Posner, Yael; Leitus, Gregory; Shimon, Linda J W; Milstein, David

    2013-10-01

    Despite considerable interest in ruthenium carbonyl pincer complexes and their substantial catalytic activity, there has been relatively little study of the isoelectronic ruthenium nitrosyl complexes. Here we describe the synthesis and reactivity of several complexes of this type as well as the catalytic activity of complex 6. Reaction of the PNP ligand (PNP = 2,6-bis((t)Bu2PCH2)pyridine) with RuCl3(NO)(PPh3)2 yielded the Ru(II) complex 3. Chloride displacement by BAr(F-) (BAr(F-) = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) gave the crystallographicaly characterized, linear NO Ru(II) complex 4, which upon treatment with NaBEt3H yielded the Ru(0) complexes 5. The crystallographically characterized Ru(0) square planar complex 5·BF4 bears a linear NO ligand located trans to the pyridilic nitrogen. Further treatment of 5·BF4 with excess LiOH gave the crystallographicaly characterized Ru(0) square planar, linear NO complex 6. Complex 6 catalyzes the dehydrogenative coupling of alcohols to esters, reaching full conversion under air or under argon. Reaction of the PNN ligand (PNN = 2-((t)Bu2PCH2)-6-(Et2NCH2)pyridine) with RuCl3(NO)(H2O)2 in ethanol gave an equilibrium mixture of isomers 7a and 7b. Further treatment of 7a + 7b with 2 equivalent of sodium isopropoxide gave the crystallographicaly characterized, bent-nitrosyl, square pyramidal Ru(II) complex 8. Complex 8 was also synthesized by reaction of PNN with RuCl3(NO)(H2O)2 and Et3N in ethanol. Reaction of the "long arm" PN(2)N ligand (PN(2)N = 2-((t)Bu2PCH2-)-6-(Et2NCH2CH2)pyridine) with RuCl3(NO)(H2O)2 in ethanol gave complex 9, which upon treatment with 2 equiv of sodium isopropoxide gave complex 10. Complex 10 was also synthesized directly by reaction of PN(2)N with RuCl3(NO)(H2O)2 and a base in ethanol. A noteworthy aspect of these nitrosyl complexes is their preference for the Ru(0) oxidization state over Ru(II). This preference is observed with both aromatized and dearomatized pincer ligands, in

  9. Temperature dependence of interlayer coupling between perpendicular magnetic [CoFeB/Pd] multilayers: Influence of interfacial CoFeB layer

    NASA Astrophysics Data System (ADS)

    Xiao, Yili; Zhang, Zongzhi; Ma, Bin; Jin, Q. Y.; Liu, Yaowen

    2014-02-01

    Temperature dependence of interlayer coupling field in the perpendicular antiferromagnetic structure of [Pd/CoFeB]2/Pd/CoFeB(tCFB)/Ru(tRu)/CoFeB(tCFB)/Pd/[CoFeB/Pd]2 is found to be sensitive to tCFB, showing various non-monotonic behaviors. The coupling strength increases with tCFB, reaching bulk-like value of up to 0.28 erg/cm2 at room temperature as tCFB is over 0.6 nm. We attribute the phenomena to interfacial effects, including lowered Curie temperature in ultrathin CoFeB layers and increased effective dead layer thickness. The coupling peak position of tRu also shifts with temperature and tCFB, corresponding to variations in dead layer thicknesses. These effects should be considered when designing practical devices employing perpendicular synthetic antiferromagnetic structures.

  10. Remarkable aspects of unsaturation in trinuclear metal carbonyl clusters: the triiron species Fe3(CO)n (n = 12, 11, 10, 9).

    PubMed

    Wang, Hongyan; Xie, Yaoming; King, R Bruce; Schaefer, Henry F

    2006-09-01

    The trinuclear iron carbonyls Fe(3)(CO)(n) (n = 12, 11, 10, 9) have been studied by density functional theory using the B3LYP and BP86 functionals. The experimentally known C(2)(v) isomer of Fe(3)(CO)(12), namely Fe(3)(CO)(10)(mu-CO)(2), is found to be the global minimum below the unbridged D(3)(h) isomer analogous to the known structures for Ru(3)(CO)(12) and Os(3)(CO)(12). The lowest-energy isomer found for Fe(3)(CO)(11) is Fe(3)(CO)(9)(mu(3)-CO)(2) with iron-iron distances in the Fe(3) triangle, suggesting the one double bond (2.460 A by B3LYP and 2.450 A by BP86) and two single bonds (2.623 A by B3LYP and 2.604 A by BP86) required to give each Fe atom the favored 18-electron configuration. Two different higher-energy dibridged structures Fe(3)(CO)(9)(mu(2)-CO)(2) are also found for Fe(3)(CO)(11). The lowest-energy isomer found for Fe(3)(CO)(10) is Fe(3)(CO)(9)(mu(3)-CO) with equivalent iron-iron distances in the Fe(3) ring (2.47 A by B3LYP or BP86). The lowest-energy isomer found for Fe(3)(CO)(9) is Fe(3)(CO)(6)(mu-CO)(3) with distances in the Fe(3) triangle possibly suggesting one single bond (2.618 A by B3LYP and 2.601 A by BP86), one weak double bond (2.491 A by B3LYP and 2.473 A by BP86), and one weak triple bond (2.368 A by B3LYP and 2.343 A by BP86). A higher-lying isomer of Fe(3)(CO)(9), i.e., Fe(3)(CO)(8)(mu-CO), at approximately 21 kcal/mol above the global minimum, has iron-iron distances strongly suggesting two single bonds (2.6 to 2.7 A) and one quadruple bond (2.068 A by B3LYP and 2.103 A by BP86). Wiberg Bond Indices are also helpful in evaluating the iron-iron bond orders. PMID:16939260

  11. Study of DNA light switch Ru(II) complexes: synthesis, characterization, photocleavage and antimicrobial activity.

    PubMed

    Yata, Praveen Kumar; Shilpa, M; Nagababu, P; Reddy, M Rajender; Kotha, Laxma Reddy; Gabra, Nazar Md; Satyanarayana, S

    2012-05-01

    The three Ru(II) complexes of [Ru(phen)(2)dppca](2+) (1) [Ru(bpy)(2)dppca](2+) (2) and [Ru(dmb)(2)dppca](2+) (3) (where phen = 1,10 phenanthroline, bpy = 2,2-bipyridine, dmb = 2 ,2-dimethyl 2',2'-bipyridine and polypyridyl ligand containing a single carboxylate functionality dppca ligand (dipyridophenazine-11-carboxylic acid) have been synthesized and characterized. These complexes have been shown to act as promising calf thymus DNA intercalators and a new class of DNA light switches, as evidenced by UV-visible and luminescence titrations with Co(2+) and EDTA, steady-state emission quenching by [Fe(CN)(6)](4-) and KI, DNA competitive binding with ethidium bromide, viscosity measurements, and DNA melting experiments. The results suggest that 1, 2, and 3 complexes bind to CT-DNA through intercalation and follows the order 1 > 2 > 3. Under irradiation at 365 nm, the three complexes have also been found to promote the photocleavage of plasmid pBR322 DNA. PMID:22194001

  12. Synthesis of novel Ru2C under high pressure-high temperature conditions.

    PubMed

    Sanjay Kumar, N R; Chandra Shekar, N V; Chandra, Sharat; Basu, Joysurya; Divakar, R; Sahu, P Ch

    2012-09-12

    We report here, for the first time, synthesis of the Fe(2)N type hexagonal phase of ruthenium carbide by a high pressure-high temperature technique using a laser heated diamond anvil cell (LHDAC). The synthesis is carried out by laser heating a mixture of pure elements, Ru and C, at very low 'pressure' of 5 GPa and T ~ 2000 K. The structure of the temperature quenched high pressure phase is characterized by in situ high pressure x-ray diffraction (HPXRD) and is corroborated by ex situ TEM imaging and diffraction, carried out for the first time on the retrieved sample synthesized by LHDAC. The lattice parameters of Ru(2)C at ambient pressure are found to be a = 2.534 Å and c = 4.147 Å. In situ HPXRD studies up to 14.2 GPa yield a bulk modulus of 178(4) GPa. Electronic structure calculations reveal the system to be metallic in nature with a degree of covalence along the Ru-C bond. As ruthenium is isoelectronic to osmium, this result for Ru(2)C has significant implications in the synthesis and study of osmium carbides. PMID:22906879

  13. Al 2O 3 supported Ru catalysts prepared by thermolysis of Ru 3(CO) 12 for catalytic wet air oxidation

    NASA Astrophysics Data System (ADS)

    Yu, Chaoying; Zhao, Peiqing; Chen, Gexin; Hu, Bin

    2011-06-01

    Low loading catalysts Ru/γ-Al 2O 3 and Ru-Ce/γ-Al 2O 3 were prepared by thermolysis of Ru 3(CO) 12 on γ-Al 2O 3. The catalysts were characterized by XPS, XRD and SEM. Two new Ru species (Ru A and Ru B) were detected during the Ru 3(CO) 12 decomposition process due to chemical interaction with the active OH groups on the surface of Al 2O 3 support, and the reduction of them can lead to more dispersed metallic phases. The sample was completely decomposed at 673 K in H 2, and RuO 2 was formed with minor amounts of Ru 0. When the temperature was increased to 773 K to heat the sample, the ratio of Ru 0 to RuO 2 increased. However, after the addition of CeO 2, only RuO 2 was detected on surface. The catalysts exhibited high activities in Catalytic Wet Air Oxidation (CWAO) of different organic compounds at high concentration such as isopropyl alcohol, phenol, acetic acids and N,N-dimethylformamide, which is attributed to the better dispersion of Ru particles and the addition of CeO 2 further enhanced number of effectively active sites on the cluster-derived catalyst surface.

  14. Skeletal Ru/Cu catalysts prepared from crystalline and quasicrystalline ternary alloy precursors: characterization by X-ray absorption spectroscopy and CO oxidation.

    PubMed

    Highfield, James; Liu, Tao; Loo, Yook Si; Grushko, Benjamin; Borgna, Armando

    2009-02-28

    . Preliminary studies in CO and H(2) oxidation were made in a DRIFTS flow reactor with on-line MS, and their activities and selectivities were compared against skeletal Ru and Cu controls, Ru/Al(2)O(3), and Au/Fe(2)O(3). All samples were active in CO oxidation above approximately 50 degrees C, showing light-off temperatures in the range 60-70 degrees C. Ru(22)Cu(7) and Ru(17)Cu(12.5) also showed good selectivities (vs. H(2) oxidation), attributed tentatively to Ru-modified Cu surfaces of varying thickness. These compositions are promising candidates to test in a (PROX) fuel processor to supply purified (CO-free) H(2) to a PEM fuel cell. PMID:19209363

  15. Oligomeric rare-earth-metal halide clusters. Three structures built of (Y{sub 16}Z{sub 4})Br{sub 36} units (Z = Ru, Ir)

    SciTech Connect

    Steinward, S.J.; Corbett, J.D.

    1996-11-20

    Suitable reactions in sealed Nb tubing at 850-950 {degrees}C gave good yields of a family of oligomeric cluster phases that were characterized by single-crystal X-ray diffraction means. The basic Y{sub 16}Z{sub 4} units ({approximately}{bar 4} symmetry) can be derived from 2+2 condensation of centered Y{sub 6}Br{sub 12}Z-type clusters or as tetracapped truncated tetrahedra Y{sub 16} that are centered by a large tetrahedral Z{sub 4}. These are surrounded by 36 bromine atoms which bridge edges or cap faces of the Y{sub 16}Z{sub 4} nuclei and, in part, bridge to metal atoms in other clusters. The principal bonding appears to be Y-Z and Y-Br, with weaker Y-Y ({bar d} {approximately} 3.70 {angstrom}) and negligible Z-Z interactions. The phase Y{sub 16}Br{sub 20}Ru{sub 4} (P4{sub 2}/nnm, Z = 2; a = 11.662(1) {angstrom}, c = 16.992 (2) {angstrom}) is isostructural with Y{sub 16}I{sub 20}Ru{sub 4} and with the new Sc{sub 16-} Br{sub 20}Z{sub 4} (Z = Fe, Os). Syntheses only in the presence of Ir and ABr-YBr{sub 3} fluxes (A = K-Cs) produce Y{sub 16-} Br{sub 24}Ir{sub 4} (Fddd, Z = 8; a = 11.718(3) {angstrom}, b = 22.361(7) {angstrom}, c = 44.702(2) {angstrom}), in which the electron-richer Ir interstitials are compensated by four additional bromine atoms and altered bridging between macroclusters. Larger amounts of YBr{sub 3} yield a third example, Y{sub 20}Br{sub 36}Ir{sub 4} (Y{sub 16}Br{sub 24}Ir{sub 4}{center_dot}4YBr{sub 3}, I4{sub 1}a, Z = 4; a = 12.699(1) {angstrom}, c = 45.11- (1){angstrom}). Here infinite zigzag chains of YBr{sub 6/2} octahedra that share cis edges lie between and bridge to the Y{sub 16}Ir{sub 4} clusters. All of these phases contain 60-electron, closed-shell macroclusters. Y{sub 16}Br{sub 20}Ru{sub 4} and Y{sub 20}Br{sub 36}ir{sub 4} were found to exhibit temperature-independent (Van Vleck) paramagnetism with values typical of those found for other rare-earth-metal, zirconium, niobium, and tantalum cluster halides.

  16. Temperature-induced transformation of electrochemically formed hydrous RuO2 layers over Ru(0001) model electrodes

    NASA Astrophysics Data System (ADS)

    Krause, Philipp P. T.; Camuka, Hava; Leichtweiss, Thomas; Over, Herbert

    2016-07-01

    Hydrous RuO2 reveals excellent performance both as a supercapacitor and as a heterogeneous oxidation catalyst. Molecular understanding of these processes needs, however, a model system with preferably low structural and morphological complexity. This goal is partly accomplished here by using single crystalline Ru(0001) as a template on which hydrous RuO2 is electrochemically formed. The hydrous RuO2 layers on Ru(0001) and their temperature induced transformation under ultra high vacuum (UHV) conditions are comprehensively characterized by scanning electron microscopy and X-ray photoemission spectroscopy. The hydrous RuO2 layer grows with an intricate morphology governed by the presence of step bunching regions of the Ru(0001) surface. Upon annealing to 200 °C in UHV the hydrous RuO2 layer transforms mostly into flat metallic Ru islands and occasionally into (100) and (111) oriented RuO2 particles aligned along the high symmetry direction of Ru(0001).Hydrous RuO2 reveals excellent performance both as a supercapacitor and as a heterogeneous oxidation catalyst. Molecular understanding of these processes needs, however, a model system with preferably low structural and morphological complexity. This goal is partly accomplished here by using single crystalline Ru(0001) as a template on which hydrous RuO2 is electrochemically formed. The hydrous RuO2 layers on Ru(0001) and their temperature induced transformation under ultra high vacuum (UHV) conditions are comprehensively characterized by scanning electron microscopy and X-ray photoemission spectroscopy. The hydrous RuO2 layer grows with an intricate morphology governed by the presence of step bunching regions of the Ru(0001) surface. Upon annealing to 200 °C in UHV the hydrous RuO2 layer transforms mostly into flat metallic Ru islands and occasionally into (100) and (111) oriented RuO2 particles aligned along the high symmetry direction of Ru(0001). Electronic supplementary information (ESI) available. See DOI: 10

  17. The synthesis and structural characterisation of [Ru(eta-Cp)(dppf)SnBr3].

    PubMed

    Paim, L A; Moura, E M; Siebald, H G L; de Lima, G M; Doriguetto, A C; Ellena, J

    2004-08-01

    The reaction of [Ru(eta-Cp)(dppf)N(3)] (1) with equimolar amount of SnBr(2) yielded an interesting heterotrimetallic compound [Ru(eta-Cp)(dppf)SnBr(3)] (2) (dppf: 1,1'-bis-diphenylphosphinoferrocene). Compounds 1 and 2 were characterised by IR, NMR (1H, 13C, 31P and 119Sn), and 2, additionally, by 57Fe and 119Sn Mössbauer spectroscopy and X-ray crystallography. The latter results were as follows: monoclinic, C2/c, a = 32.8879(4)A, b = 11.9888(2)A, c = 20.8986(3)A, beta = 92.545(1)degrees, V = 8231.9(2)A(3), Z =8. PMID:15249029

  18. The synthesis and structural characterisation of [Ru(η-Cp)(dppf)SnBr 3

    NASA Astrophysics Data System (ADS)

    Paim, L. A.; Moura, E. M.; Siebald, H. G. L.; de Lima, G. M.; Doriguetto, A. C.; Ellena, J.

    2004-08-01

    The reaction of [Ru(η-Cp)(dppf)N 3] ( 1) with equimolar amount of SnBr 2 yielded an interesting heterotrimetallic compound [Ru(η-Cp)(dppf)SnBr 3] ( 2) (dppf: 1,1'-bis-diphenylphosphinoferrocene). Compounds 1 and 2 were characterised by IR, NMR ( 1H, 13C, 31P and 119Sn), and 2, additionally, by 57Fe and 119Sn Mössbauer spectroscopy and X-ray crystallography. The latter results were as follows: monoclinic, C2/ c, a=32.8879(4) Å, b=11.9888(2) Å, c=20.8986(3) Å, β=92.545(1)°, V=8231.9(2) Å 3, Z=8.

  19. Disruption of OsYSL15 leads to iron inefficiency in rice plants.

    PubMed

    Lee, Sichul; Chiecko, Jeff C; Kim, Sun A; Walker, Elsbeth L; Lee, Youngsook; Guerinot, Mary Lou; An, Gynheung

    2009-06-01

    Uptake and translocation of metal nutrients are essential processes for plant growth. Graminaceous species release phytosiderophores that bind to Fe(3+); these complexes are then transported across the plasma membrane. We have characterized OsYSL15, one of the rice (Oryza sativa) YS1-like (YSL) genes that are strongly induced by iron (Fe) deficiency. The OsYSL15 promoter fusion to beta-glucuronidase showed that it was expressed in all root tissues when Fe was limited. In low-Fe leaves, the promoter became active in all tissues except epidermal cells. This activity was also detected in flowers and seeds. The OsYSL15:green fluorescent protein fusion was localized to the plasma membrane. OsYSL15 functionally complemented yeast strains defective in Fe uptake on media containing Fe(3+)-deoxymugineic acid and Fe(2+)-nicotianamine. Two insertional osysl15 mutants exhibited chlorotic phenotypes under Fe deficiency and had reduced Fe concentrations in their shoots, roots, and seeds. Nitric oxide treatment reversed this chlorosis under Fe-limiting conditions. Overexpression of OsYSL15 increased the Fe concentration in leaves and seeds from transgenic plants. Altogether, these results demonstrate roles for OsYSL15 in Fe uptake and distribution in rice plants. PMID:19376836

  20. Level structure of /sup 101/Ru from the /sup 100/Ru(d,p) reaction

    SciTech Connect

    Duarte, J.L.M.; Horodynski-Matsushigue, L.B.; Borello-Lewin, T.; Dietzsch, O.

    1988-08-01

    Energy levels of /sup 101/Ru have been studied by the /sup 100/Ru(d,p)/sup 101/Ru reaction at an incident deuteron energy of 12 MeV. Outgoing particles were momentum analyzed by a magnetic spectrograph and detected in nuclear emulsion plates, with an energy resolution of 7.5 keV. A total of 68 levels up to 3.2 MeV excitation energy was identified, about two-thirds of them reported for the first time. Experimental angular distributions were compared to distorted-wave Born approximation predictions and reduced spectroscopic factors obtained. The total l = 2 and 75% of l = 0, 4, and 5 spectroscopic strengths were located. Attention is drawn to transitions to low-lying states in /sup 101/Ru (below E/sub exc/ = 0.75 MeV) with l = 3 and l = 1 character.

  1. Chemical vapour deposition of amorphous Ru(P) thin films from Ru trialkylphosphite hydride complexes.

    PubMed

    McCarty, W Jeffrey; Yang, Xiaoping; DePue Anderson, Lauren J; Jones, Richard A

    2012-11-21

    The ruthenium phosphite hydride complexes H(2)Ru(P(OR)(3))(4) (R = Me (1), Et (2), (i)Pr (3)) were used as CVD precursors for the deposition of films of amorphous ruthenium-phosphorus alloys. The as-deposited films were X-ray amorphous and XPS analysis revealed that they were predominantly comprised of Ru and P in zero oxidation states. XPS analysis also showed the presence of small amounts of oxidized ruthenium and phosphorus. The composition of the films was found to depend on ligand chemistry as well as the deposition conditions. The use of H(2) as the carrier gas had the effect of increasing the relative concentrations of P and O for all films. Annealing films to 700 °C under vacuum produced films of polycrystalline hcp Ru while a flowing stream of H(2) resulted in polycrystalline hcp RuP. PMID:23018487

  2. Preparation, structure and mechanical properties of RuAl and (Ru,Ni)Al alloys

    SciTech Connect

    Sabariz, A.L.R.; Taylor, G.

    1997-12-31

    The intermetallic compound, RuAl with B2 CsCl type structure, has been shown to possess room-temperature toughness and plasticity. NiAl also forms a B2 compound and it is claimed that a pseudo-binary compound, (Ru,Ni)Al, may be formed because the difference in lattice parameter between the two binary phases is slight. In this work a study has been made of the mechanical properties of some polycrystalline compounds, across the RuAl-(Ru,Ni)Al pseudo-binary, prepared from high-purity elemental powders. Compressive yield stresses were measured between room-temperature and 900 C, and the mechanisms of plastic flow are discussed in relation to the dislocation structures observed by TEM. Hot-microhardness tests were made to provide an indication of the effect of solid-solution hardening.

  3. Congress delves into science with RU-486.

    PubMed

    Kaeser, L

    1998-12-01

    In June 1998, a conservative, Republican member of the US House of Representatives attempted to amend the 1999 bill authorizing funding for the US Food and Drug Administration (USFDA) to prevent government funds from being used to test, develop, or approve "any drug for the chemical inducement of abortion." This bill was designed to halt the approval process for RU-486, a drug that was deemed "approvable" by the USFDA in 1996. Arguments mounted against the amendment by medical, health, and research groups stated that 1) RU-486 is an advance because it permits abortions early in pregnancies, 2) it is improper for the US Congress to impose a scientific judgement on the USFDA, and 3) this amendment has adverse implications for a wide range of drugs and devices that might have an abortifacient effect but be approved for other uses. The House of Representatives passed the amendment but the Senate rejected it, and it was deleted from the final version of the legislation. The amendment is expected to resurface next year. The Congressional debate on RU-486 also spilled over into the appointment hearings for the nomination of Jane Henney as USFDA commissioner. During her confirmation process, Henney was grilled about whether she would grant final approval to RU-486. Henney's nomination was approved by committee but has not yet been considered by the full Senate. PMID:12321809

  4. Hexadecapolar excitation in sup 100 Ru

    SciTech Connect

    Sirota, S.; Duarte, J.L.M.; Horodynski-Matsushigue, L.B.; Borello-Lewin, T. )

    1989-09-01

    Attention is drawn to the strong collective {ital L}=4 direct excitation of the state at 2.367 MeV in {sup 100}Ru by inelastic scattering of 16 MeV protons characterized by a deformation parameter {beta}{sub 4}=0.10, one of the highest reported for any region of the mass table.

  5. Lubiprostone: RU 0211, SPI 0211.

    PubMed

    2005-01-01

    Lubiprostone [RU 0211, SPI 0211] is a bicyclic fatty acid that acts as a chloride channel opener, increasing intestinal water secretion. Lubiprostone, an orally-administered formulation, is one of a series of functional fatty acid compounds discovered by Dr Ryuji Ueno, and is currently undergoing development for the treatment of constipation, constipation-predominant irritable bowel syndrome (IBS-C) and postoperative ileus with Sucampo Pharmaceutical's. Lubiprostone activates a specific chloride channel (CLC2) on cells lining the gut, thereby naturally increasing intestinal fluid secretion. The increased fluid level softens the stool, promotes spontaneous bowel movements, and reduces abdominal discomfort/pain and bloating. The chloride channel is a protein that controls cell membrane transport of chloride ion. Lubiprostone acts on the ClC-2 chloride channel, which is located in the apical intestinal membrane. In November 2004, Takeda Pharmaceuticals entered into a collaboration and licensing agreement for Lubiprostone with Sucampo Pharmaceuticals for the treatment of chronic constipation and constipation-predominant Irritable Bowel Syndrome (c-IBS). Under the terms of the agreement, Takeda received the right to market the product in the US and Canada, while Sucampo reserved the co-promotion rights for these countries. Takeda's wholly-owned US subsidiary, Takeda Pharmaceuticals North America Inc., will sell lubiprostone once the product is approved by the US FDA. Takeda will also receive an option for marketing rights in other territories, including Japan and Europe. Takeda and Sucampo agreed on the exclusive manufacturing and supply of Lubiprostone by R-Tech Ueno, Ltd, a member of the Sucampo Group. Sucampo has the potential to receive up to dollar US 210 million in initial and milestone payments, some of which are contingent upon the successful achievement of several milestones. Takeda will fund a major part of development costs not only for chronic constipation

  6. Heat capacity and heat content measurements on binary compounds in the Ru-Si, Ru-Ge, and Ru-Sn systems

    SciTech Connect

    Kuntz, J.J.; Gachon, J.C.; Feschotte, P.; Perring, L. |

    1997-11-01

    Molar heat capacities of Ru{sub 0.5}Si{sub 0.5} Ru{sub 0.4}Si{sub 0.6}, Ru{sub 0.5}Ge{sub 0.5}, Ru{sub 0.4}Ge{sub 0.6}, Ru{sub 0.4}Sn{sub 0.6}, and Ru{sub 0.3}Sn{sub 0.7} were determined every 10 K by differential scanning calorimetry in the temperature range from 310 to 1080 K. The present results have been fitted by a polynomial function of temperature: C{sub p} = a+bT-cT{sup -2}. Heat contents of the six phases have been verified by drop calorimetry. Standard enthalpies of formation are given for the studied compounds.

  7. Light-induced water oxidation catalyzed by an oxido-bridged triruthenium complex with a Ru-O-Ru-O-Ru motif.

    PubMed

    Tsubonouchi, Yuta; Lin, Shu; Parent, Alexander R; Brudvig, Gary W; Sakai, Ken

    2016-06-28

    A μ-oxido-bridged triruthenium complex (RuT(2+)), formed by air-oxidation of a previously reported monoruthenium water oxidation catalyst (WOC), serves as an efficient photochemical WOC with the turnover frequency (TOF) and turnover number (TON) 0.90 s(-1) and 610, respectively. The crystal structures of RuT(2+) and its one-electron oxidized RuT(3+) are also reported. PMID:27264497

  8. s-Process Os isotope enrichment in ureilites by planetary processing

    NASA Astrophysics Data System (ADS)

    Goderis, S.; Brandon, A. D.; Mayer, B.; Humayun, M.

    2015-12-01

    Ubiquitous nucleosynthetic isotope anomalies relative to the terrestrial isotopic composition in Mo, Ru, and other elements are known from both bulk chondrites and differentiated meteorites, but Os isotope ratios reported from such meteorites have been found to be indistinguishable from the terrestrial value. The carriers of s- and r-process Os must thus have been homogeneously distributed in the solar nebula. As large Os isotope anomalies are known from acid leachates and residues of primitive chondrites, the constant relative proportions of presolar s- and r-process carriers in such chondrites must have been maintained during nebular processes. It has long been assumed that partial melting of primitive chondrites would homogenize the isotopic heterogeneity carried by presolar grains. Here, ureilites, carbon-rich ultramafic achondrites dominantly composed of olivine and low-Ca pyroxene, are shown to be the first differentiated bulk Solar System materials for which nucleosynthetic Os isotope anomalies have been identified. These anomalies consist of enrichment in s-process Os heterogeneously distributed in different ureilites. Given the observed homogeneity of Os isotopes in all types of primitive chondrites, this Os isotope variability among ureilites must have been caused by selective removal of s-process-poor Os host phases, probably metal, during rapid localized melting on the ureilite parent body. While Mo and Ru isotope anomalies for all meteorites measured so far exhibit s-process deficits relative to the Earth, the opposite holds for the Os isotope anomalies in ureilites reported here. This might indicate that the Earth preferentially accreted olivine-rich restites and inherited a s-process excess relative to smaller meteorite bodies, consistent with Earth's high Mg/Si ratio and enrichment of s-process nuclides in Mo, Ru, and Nd isotopes. Our new Os isotope results imply that caution must be used when applying nucleosynthetic isotope anomalies as provenance

  9. Ru-assisted synthesis of Pd/Ru nanodendrites with high activity for ethanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Zhang, Ke; Bin, Duan; Yang, Beibei; Wang, Caiqin; Ren, Fangfang; Du, Yukou

    2015-07-01

    Due to the specific physical and chemical properties of a highly branched noble metal, the controllable synthesis has attracted much attention. This article reports the synthesis of Pd/Ru nanodendrites by a facile method using an oil bath in the presence of polyvinyl pyrrolidone, potassium bromide and ascorbic acid. The morphology, structure, and composition of the as-prepared catalysts were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. In the electrochemical measurement, the as-prepared Pd7/Ru1 bimetallic nanodendrites provide a large electrochemically active surface area and exhibit high peak current density in the forward scan toward ethanol electrooxidation, which is nearly four times higher than those of a pure Pd catalyst. The as-prepared Pd7/Ru1 catalysts also exhibit significantly enhanced cycling stability toward ethanol oxidation in alkaline medium, which are mainly ascribed to the synergetic effect between Pd and Ru. This indicates that the Pd7/Ru1 catalysts should have great potential applications in direct ethanol fuel cells.Due to the specific physical and chemical properties of a highly branched noble metal, the controllable synthesis has attracted much attention. This article reports the synthesis of Pd/Ru nanodendrites by a facile method using an oil bath in the presence of polyvinyl pyrrolidone, potassium bromide and ascorbic acid. The morphology, structure, and composition of the as-prepared catalysts were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. In the electrochemical measurement, the as-prepared Pd7/Ru1 bimetallic nanodendrites provide a large electrochemically active surface area and exhibit high peak current density in the forward scan toward ethanol electrooxidation, which is nearly four times higher than those of a pure Pd catalyst. The as-prepared Pd7/Ru1 catalysts also exhibit significantly

  10. Temperature-induced transformation of electrochemically formed hydrous RuO2 layers over Ru(0001) model electrodes.

    PubMed

    Krause, Philipp P T; Camuka, Hava; Leichtweiss, Thomas; Over, Herbert

    2016-08-01

    Hydrous RuO2 reveals excellent performance both as a supercapacitor and as a heterogeneous oxidation catalyst. Molecular understanding of these processes needs, however, a model system with preferably low structural and morphological complexity. This goal is partly accomplished here by using single crystalline Ru(0001) as a template on which hydrous RuO2 is electrochemically formed. The hydrous RuO2 layers on Ru(0001) and their temperature induced transformation under ultra high vacuum (UHV) conditions are comprehensively characterized by scanning electron microscopy and X-ray photoemission spectroscopy. The hydrous RuO2 layer grows with an intricate morphology governed by the presence of step bunching regions of the Ru(0001) surface. Upon annealing to 200 °C in UHV the hydrous RuO2 layer transforms mostly into flat metallic Ru islands and occasionally into (100) and (111) oriented RuO2 particles aligned along the high symmetry direction of Ru(0001). PMID:27009374