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Sample records for title compound fe

  1. The Moessbauer effect in Fe(III) HEDTA, Fe(III) EDTA, and Fe(III) CDTA compounds

    International Nuclear Information System (INIS)

    Prado, F.R.

    1989-01-01

    The dependence of Moessbauer spectra with pH value of Fe(III)HEDTA and Fe(III)CDTA compounds is studied. Informations on formation processes of LFe-O-FeL (L=ligand) type dimers by the relation of titration curves of Fe(III)EDTA, Fe(III)HEDTA and Fe(III)CDTA compounds with the series of Moessbauer spectra, are obtained. Some informations on Fe-O-Fe bond structure are also obtained. Comparing the titration curves with the series of Moessbauer spectra, it is concluded that the dimerization process begins when a specie of the form FeXOH α (X = EDTA, HEDTA, CDTA; α = -1, -2) arises. (M.C.K.) [pt

  2. Thermodynamic stability studies of Ce-Sb compounds with Fe

    Science.gov (United States)

    Xie, Yi; Zhang, Jinsuo; Benson, Michael T.; Mariani, Robert D.

    2018-02-01

    Lanthanide fission products can migrate to the fuel periphery and react with cladding, causing fuel-cladding chemical interaction (FCCI). Adding a fuel additive dopant, such as Sb, can bind lanthanide, such as Ce, into metallic compounds and thus prevent migration. The present study focuses on the thermodynamic stability of Ce-Sb compounds when in contact with the major cladding constituent Fe by conducting diffusion couple tests. Ce-Sb compounds have shown high thermodynamic stability as they did not react with Fe. When Fe-Sb compounds contacted with Ce, Sb was separated out of Fe-Sb compounds and formed the more stable Ce-Sb compounds.

  3. μ(4)-Orthothio-carbonato-tetra-kis-[tri-carbonyl-iron(I)](2 Fe-Fe).

    Science.gov (United States)

    Shi, Yao-Cheng; Cheng, Huan-Ren; Yuan, Li-Min; Li, Qian-Kun

    2011-11-01

    The fused bis-butterfly-shaped title compound, [Fe(4)(CS(4))(CO)(12)], possesses an orthothio-carbonate (CS(4) (4-)) ligand that acts as a bridge between two Fe(2)(CO)(6) units. A short intra-molecular S⋯S contact [2.6984 (8) and 2.6977 (8) Å] occurs in each S(2)Fe(2)(CO)(6) fragment.

  4. Magnetostriction of rare earth-Fe2 Laves phase compounds

    International Nuclear Information System (INIS)

    Clark, A.E.; Abbundi, R.; Savage, H.T.

    1977-01-01

    Single crystal magnetostriction measurements were made as a function of temperature on TbFe 2 and DyFe 2 . From these, the intrinsic magnetoelastic coupling coefficients were determined for the rare earth-Fe 2 compounds. Employing X-ray techniques, certain multicomponent rare earth-Fe 2 compounds were identified to maximize the magnetostriction to anisotropy ratio. (Auth.)

  5. Environmental embrittlement of intermetallic compounds in Fe-Al alloys

    Institute of Scientific and Technical Information of China (English)

    张建民; 张瑞林; S.H.YU; 余瑞璜

    1996-01-01

    First,it is proposed that hydrogen atoms occupy the interstitial sites in Fe3Al and FeAl.Then the environmental embrittlement of intermetallic compounds in Fe-Al alloys is studied in the light of calculated valence electron structures and bond energy of Fe3Al and FeAl containing hydrogen atoms.From the analyses it is found that the states of metal atoms will change,in which more lattice electrons will become covalent electrons to bond with hydrogen atoms when the atomic hydrogen diffuses into the intermetallic compounds in Fe-Al alloys,which will result in the decrease of local metallicity in Fe3Al and FeAl.Meanwhile,it is found that the crystal will easily cleave since solute hydrogen bonds with metal atoms and severely anisotropic bonds form.As a conclusion,these factors result in the environmental embrittlement of Fe3Al and FeAl.

  6. Structure and magnetic transition of LaFe13-xSix compounds

    International Nuclear Information System (INIS)

    Bo Liuxu; Altounian, Z; Ryan, D H

    2003-01-01

    Structure and magnetic transitions were investigated by x-ray diffraction and Moessbauer spectroscopy in LaFe 13-x Si x compounds with x = 1.6, 2.0 and 2.6. With increasing Si content, the La-Fe interatomic distance decreased while the average Fe-Fe distance increased. These changes affect the structural stability and the magnetic properties of the compounds. The temperature dependence of the hyperfine field for the compound with x = 2.6 can be fitted very well using a mean field model with a Brillouin function (BF) while that for the compounds with x = 1.6 and 2.0 changes more sharply than that predicted by the BF relation near the Curie temperature. The different nature of the magnetic transition with different Si content originates from the spatial distribution of the Si atoms and related variation of the La-(Fe, Si) and the Fe-Fe distances in the cubic NaZn 13 structure

  7. Magnetic properties of FeZr{sub 2} and Fe{sub 2}Zr intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Prajapat, C. L., E-mail: prajapat@barc.gov.in; Singh, M. R.; Mishra, P. K. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, INDIA-400085 (India); Chattaraj, D. [Product Development Division, Bhabha Atomic Research Centre, Mumbai, INDIA-400085 (India); Mishra, R. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai, INDIA-400085 (India); Ravikumar, G. [Scientific Information Resources Division, Bhabha Atomic Research Centre, Mumbai, INDIA-400085 (India)

    2016-05-23

    Magnetic properties of Fe-Zr system, viz., FeZr{sub 2} and Fe{sub 2}Zr have been studied. Both the compounds show soft ferromagnetic behavior. Curie temperature is well above the room temperature. Lower saturation magnetization for the zirconium rich sample, FeZr{sub 2}, could be due to possible donation of electrons from the Zr-rich neighbors to Fe atoms or diminution of long range magnetic order by defects.

  8. MnFe(PGe) compounds: Preparation, structural evolution, and magnetocaloric effects

    International Nuclear Information System (INIS)

    Yue Ming; Zhang Hong-Guo; Zhang Jiu-Xing; Liu Dan-Min

    2015-01-01

    The interdependences of preparation conditions, magnetic and crystal structures, and magnetocaloric effects (MCE) of the MnFePGe-based compounds are reviewed. Based upon those findings, a new method for the evaluation of the MCE in these compounds, based on differential scanning calorimetry (DSC), is proposed. The MnFePGe-based compounds are a group of magnetic refrigerants with giant magnetocaloric effect (GMCE), and as such, have drawn tremendous attention, especially due to their many advantages for practical applications. Structural evolution and phase transformation in the compounds as functions of temperature, pressure, and magnetic field are reported. Influences of preparation conditions upon the homogeneity of the compounds’ chemical composition and microstructure, both of which play a key role in the MCE and thermal hysteresis of the compounds, are introduced. Lastly, the origin of the “virgin effect” in the MnFePGe-based compounds is discussed. (paper)

  9. Investigations on the parent compounds of Fe-chalcogenide superconductors

    International Nuclear Information System (INIS)

    Koz, Cevriye

    2015-01-01

    This work is focused on the parent compounds of the Fe-chalcogenide superconductors. For this purpose poly- and single-crystalline forms of tetragonal β-Fe x Se, Fe 1+y Te, Fe 1+y Te 1-x Se x and Fe (1+y)-x M x Te (M = Ni, Co) have been prepared. Second focal points of this study are the low-temperature structural phase transitions and physical property changes in tetragonal Fe 1+y Te which are induced by composition, external pressure, and cationic substitution.

  10. Cs[FeSe{sub 2}], Cs{sub 3}[FeSe{sub 2}]{sub 2}, and Cs{sub 7}[Fe{sub 4}Se{sub 8}]. Missing links of known chalcogenido ferrate series

    Energy Technology Data Exchange (ETDEWEB)

    Stueble, Pirmin; Roehr, Caroline [Institut fuer Anorganische und Analytische Chemie, Universitaet Freiburg (Germany)

    2017-11-17

    The three cesium selenido ferrate title compounds with an Se:Fe ratio of 2:1 were synthesized from stoichiometric samples reacting elemental Cs either (A) with Fe and Se in a double-crucible setup (Cs[FeSe{sub 2}], Cs{sub 3}[FeSe{sub 2}]{sub 2}) or (B) with previously prepared FeSe{sub 2} (Cs{sub 3}[FeSe{sub 2}]{sub 2}, Cs{sub 7}[Fe{sub 4}S{sub 8}]) (T{sub max} = 800-1000 C). The pure Fe{sup III} ferrate Cs[FeSe{sub 2}] crystallizes in the Tl[FeSe{sub 2}] type [monoclinic, space group C2/m, a = 1392.95(10), b = 564.43(3), c = 737.44(6) pm, β = 119.163(5) , Z = 4, R{sub 1} = 0.0550]. It is thus not isotypic to all other alkali ferrates(III) A[FeS{sub 2}] and A[FeSe{sub 2}] containing chains of edge-sharing tetrahedra, but crystallizes in a t2 subgroup of the Immm structure of Cs[FeS{sub 2}]. The mixed-valent chain compound Cs{sub 3}[FeSe{sub 2}]{sub 2} is isotypic to its sulfido analogue [orthorhombic, space group Pnma, a = 777.88(6), b = 1151.02(6), c = 1341.61(7) pm, Z = 4, R{sub 1} = 0.0470]. In contrast to the isopunctal Na{sub 3}[FeSe{sub 2}]{sub 2} type K/Rb compounds the chains are only slightly corrugated. The monoclinic, likewise mixed-valent Fe{sup II/III} selenido ferrate Cs{sub 7}[Fe{sub 4}Se{sub 8}] [monoclinic, space group C2/c, a = 1953.79(10), b = 879.71(5), c = 1717.03(10) pm, β = 117.890(2) , Z = 4, R{sub 1} = 0.0816] is isostructural both to the cesium sulfido and tellurido compound. The structure contains oligomeric moieties of four edge sharing [FeSe{sub 4}] tetrahedra forming slightly distorted tetrahedral clusters [Fe{sub 4}Se{sub 8}]{sup 7-}, which are surrounded by a cube of 26 Cs cations. Based on a structure map, the crystal chemistry of the three title compounds is discussed together with all chain/cluster ferrates of the general series A{sub 1+x}[Fe{sup III}{sub 1-x}Fe{sup II}{sub x}Q{sub 2}] (x = 0-1; A = Na, K, Rb, Cs; Q = S, Se, Te). (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Magnetic properties of Nd3(Fe,Mo)29 compound and its nitride

    International Nuclear Information System (INIS)

    Pan Hongge

    1998-01-01

    The iron-rich ternary intermetallic compound Nd 3 (Fe,Mo) 29 with the Nd 3 (Fe,Ti) 29 -type monoclinic structure and its nitride were prepared. After nitrogenation, the nitride retains the structure of the parent compound, but the unit-cell volume of the nitride is 5.9% greater than that of the parent compound. The Curie temperature of Nd 3 (Fe,Mo) 29 nitride is 70.9% higher than that of the parent compound and the saturation magnetization of the nitride is about 6.6% (at 4.2 K) and 23.7% (at 300 K) higher than that of the parent compound. The anisotropy of the nitride is similar to that of parent compound, which exhibits plane anisotropy. (orig.)

  12. Structure and magnetic properties of Y2Fe17-xMnx compounds (x=0-6)

    International Nuclear Information System (INIS)

    Wang Yingang; Zhejiang Univ., Hangzhou; Yang Fuming; Chen Changpin; Tang Ning; Pan Hongge; Zhejiang Univ., Hangzhou; Wang Qidong

    1996-01-01

    The effect of Mn on structure and magnetic properties of Y 2 Fe 17-x Mn x compounds has been studied. Substitution of Mn for Fe does not change the structure of Y 2 Fe 17 , and all the Y 2 Fe 17-x Mn x compounds crystallize in Th 2 Ni 17 structure. The lattice constants first increase, then slightly decrease, and finally increase again. The Curie temperature of Y 2 Fe 17-x Mn x compounds first increases, shows a maximum at x=0.3, and then decreases again. The saturation magnetization of Y 2 Fe 17-x Mn x compounds decreases dramatically with increasing Mn content. The moments of Mn atoms in these compounds are also discussed. (orig.)

  13. Compounds of Fe-Zn bond

    International Nuclear Information System (INIS)

    Mauro, A.E.; Mancini, M.N.G.

    1981-01-01

    The compounds of the type L 1 L 2 ZnFe(CO) 4 , not yet reported, are synthesized and studied by infrared spectroscopy. The data are interpreted based on a monomeric structure with a local C sub(3v) symmetry around the iron atom. L 1 = methylamine (Mea), dimethylamine (diMea), trimethylamine (triMea) L 2 = ethylenediamine (en), N-methylethylenediamine (N,Meen), N,N-dimethylenthylenediamines, (s-diMeen). (Author) [pt

  14. Magnetic properties of Fe-rich rare-earth intermetallic compounds with a ThMn12 structure

    International Nuclear Information System (INIS)

    Ohashi, K.; Tawara, Y.; Osugi, R.; Shimao, M.

    1988-01-01

    Sm(Fe/sub 1-//sub x/M/sub x/) 12 ternary compounds based on the tetragonal ThMn 12 structure where M is Ti, Si, V, Cr, and Mo were investigated. M atoms have a preference for site occupation. Ti atoms occupy the 8i or 8j site and Cr atoms occupy the 8i site. Curie temperatures on Sm(M,Fe) 12 compounds are around 590 K except for the SmMo 2 Fe 10 compound (T/sub c/ = 483 K). The SmTiFe 11 and SmSi 2 Fe 10 compounds have a high saturation magnetization and magnetic anisotropy

  15. Investigation of transport properties of FeTe compound

    Science.gov (United States)

    Lodhi, Pavitra Devi; Solanki, Neha; Choudhary, K. K.; Kaurav, Netram

    2018-05-01

    Transport properties of FeTe parent compound has been investigated by measurements of electrical resistivity, magnetic susceptibility and Seebeck coefficient. The sample was synthesized through a standard solid state reaction route via vacuum encapsulation and characterized by x-ray diffraction, which indicated a tetragonal phase with space group P4/nmm. The parent FeTe compound does not exhibit superconductivity but shows an anomaly in the resistivity measurement at around 67 K, which corresponds to a structural phase transition along with in the vicinity of a magnetic phase transition. In the low temperature regime, Seebeck coefficient, S(T), exhibited an anomalous dip feature and negative throughout the temperature range, indicating electron-like charge carrier conduction mechanism.

  16. Magnetic phase transitions in R2Fe17 compounds under pressure

    International Nuclear Information System (INIS)

    Arnold, Z.; Kamarad, J.

    1994-01-01

    The effect of the pressure up to 1.4 GPa on the Curie temperature T c in the R 2 Fe 17 intermetallics with R = Nd, Er and Y was measured using a low field susceptibility technique. The identical character of the temperature dependence of susceptibility χ(T) of the R 2 Fe 17 intermetallics observed at ambient pressure (sharp step-like drop at T c ) is preserved at high pressures only in the case of Nd 2 Fe 17 . Pronounced broadening and splitting of the sharp drop of χ(T) was observed in Er 2 Fe 17 and Y 2 Fe 17 respectively. The initial pressure slopes of dTc/dp are large and negative for all studied compounds, having nearly the same values (dTc/dp = -36K/GPa for Nd 2 Fe 17 compound). The results are discussed from the point of view of the sensitivity of T c on the crystal structure, the number of nearest neighbors of Fe atoms and the possible effect of disordered structures in the R 2 Fe 17 intermetallics

  17. (CaFeAs)10PtzAs8 superconductors and related compounds

    International Nuclear Information System (INIS)

    Stuerzer, Tobias

    2015-01-01

    The main topic of this dissertation is the identification of new compounds, structure determination, and substitution dependent investigation of properties in this new branch of the family of iron arsenide superconductors (Chapter 2). Chapter 2.1 presents the identification of the superconducting compounds and the corresponding structure elucidation identifying two dif-ferent species (CaFeAs) 10 Pt 3 As 8 and (CaFeAs) 10 Pt 4 As 8 in this family (abbreviated as 1038 and 1048 according to their stoichiometry). However, a closer look revealed a more challenging structure chemistry which is covered in Chapter 2.2. The following two Chapters 2.3 and 2.4 are devoted to (CaFeAs) 10 Pt 3 As 8 and more detailed investigations on this parent compound of the new superconductor family. Furthermore, transition metal substitution series (CaFe 1-x M x As) 10 Pt 3 As 8 were synthesized to investigate the resemblance to model systems Ba(Fe 1-x M x ) 2 As x and LaO(Fe 1-x M x )As in the scope of structural changes and superconductivity as described in Chapter 2.5. Initially amazing differences in superconducting properties com-paring 1038 and 1048 compounds are analyzed in Chapter 2.6 establishing an universal dop-ing model in the (CaFe 1-x M x As) 10 Pt z As 8 family. Additionally substituent dependent properties upon rare earth substitution in electron doped (Ca 1-y RE y FeAs) 10 Pt 3 As 8 are investigated in Chapter 2.7, while a detailed study of superconducting properties and magnetism in (Ca 1-y La y FeAs) 10 Pt 3 As 8 by the local μSR technique is presented in Chapter 2.8. In Chapter 2.9 a comparison of direct and electron doping is discussed based on codoping experiments in (Ca 1-y La y Fe 1-x Pt x As) 10 Pt 3 As 8 and (CaFe 1-x Pt x As) 10 Pt 4 As 8 . Finally, in Chapter 2.10 electron doping in stoichiometric 1048 is studied by charge compensation experiments in (Ca 1-y Na y FeAs) 10 Pt 4 As 8 . Chapter 3 is dedicated to a new family of calcium iron arsenides featuring

  18. High-Tc Superconductors Based on FeAs Compounds

    CERN Document Server

    Izyumov, Yuri

    2010-01-01

    Physical properties and models of electronic structure are analyzed for a new class of high-TC superconductors which belong to iron-based layered compounds. Despite their variable chemical composition and differences in the crystal structure, these compounds possess similar physical characteristics, due to electron carriers in the FeAs layers and the interaction of these carriers with fluctuations of the magnetic order. A tremendous interest towards these materials is explained by the prospects of their practical use. In this monograph, a full picture of the formation of physical properties of these materials, in the context of existing theory models and electron structure studies, is given. The book is aimed at a broad circle of readers: physicists who study electronic properties of the FeAs compounds, chemists who synthesize them and specialists in the field of electronic structure calculations in solids. It is helpful not only to researchers active in the fields of superconductivity and magnetism, but also...

  19. Magnetic structure and phase formation of magnetocaloric Mn-Fe-P-X compounds

    NARCIS (Netherlands)

    Ou, Z.Q.

    2013-01-01

    This thesis presents a study of the crystal and magnetic structure, the magnetocaloric effect and related physical properties in Mn-Fe-P-X compounds. The influences of boron addition in (Mn,Fe)2(P,As) compounds have been studied. It is found that boron atoms occupy interstitial sites within the

  20. Metamagnetic behaviour of La1-xGdxFe12B6 compounds

    International Nuclear Information System (INIS)

    Li, Q.A.; Groot, C.H. de; Boer, F.R. de; Buschow, K.H.J.

    1997-01-01

    The magnetic properties of compounds of the type La 1-x Gd x Fe 12 B 6 have been studied in high magnetic fields at 4.2 K. LaFe 12 B 6 is a compound with Fe moments close to magnetic instability and values not larger than about 0.5 μ B . Substitution of Gd for part of the La and application of high magnetic fields enhance the Fe moments to values in excess of 2 μ B . The high-moment state in LaFe 12 B 6 is reached via a metamagnetic transition. This first-order transition is associated with an extremely large hysteresis of nearly 7 T at 4.2 K. (orig.)

  1. Theoretical calculations of valence states in Fe-Mo compounds

    International Nuclear Information System (INIS)

    Estrada, F; Navarro, O; Noverola, H; Suárez, J R; Avignon, M

    2014-01-01

    The half-metallic ferromagnetic double perovskite compound Sr 2 FeMoO 6 is considered as an important material for spintronic applications. It appears to be fundamental to understand the role of electronic parameters controlling the half-metallic ground state. Fe-Mo double perovskites usually present some degree of Fe/Mo disorder which generally increases with doping. In this work, we study the valence states of Fe-Mo cations in the off-stoichiometric system Sr 2 Fe 1+x Mo 1−x O 6 (−1 ≤ x ≤ 1/3) with disorder. Our results for Fe and Mo valence states are obtained using the Green functions and the renormalization perturbation expansion method. The model is based on a correlated electron picture with localized Fe-spins and conduction Mo-electrons interacting with the local spins via a double-exchange-type mechanism

  2. Abnormal thermal expansion properties of cubic NaZn13-type La(Fe,Al)13 compounds.

    Science.gov (United States)

    Li, Wen; Huang, Rongjin; Wang, Wei; Zhao, Yuqiang; Li, Shaopeng; Huang, Chuanjun; Li, Laifeng

    2015-02-28

    The cubic NaZn13-type La(Fe,Al)13 compounds were synthesized, and their linear thermal expansion properties were investigated in the temperature range of 4.2-300 K. It was found that these compounds exhibit abnormal thermal expansion behavior, i.e., pronounced negative thermal expansion (NTE) or zero thermal expansion (ZTE) behavior, below the Curie temperature due to the magnetovolume effect (MVE). Moreover, in the La(Fe,Al)13 compounds, the modification of the coefficient of thermal expansion (CTE) as well as the abnormal thermal expansion (ATE) temperature-window is achieved through optimizing the proportion of Fe and Al. Typically, the average CTE of the LaFe13-xAlx compounds with x = 1.8 reaches as large as -10.47 × 10(-6) K(-1) between 100 and 225 K (ΔT = 125 K). Also, the ZTE temperature-window of the LaFe13-xAlx compounds with x = 2.5 and x = 2.7 could be broadened to 245 K (from 5 to 250 K). Besides, the magnetic properties of these compounds were measured and correlated with the abnormal thermal expansion behavior. The present results highlight the potential application of such La(Fe,Al)13 compounds with abnormal thermal expansion properties in cryogenic engineering.

  3. Giant negative thermal expansion in NaZn13-type La(Fe, Si, Co)13 compounds.

    Science.gov (United States)

    Huang, Rongjin; Liu, Yanying; Fan, Wei; Tan, Jie; Xiao, Furen; Qian, Lihe; Li, Laifeng

    2013-08-07

    La(Fe, Si)13-based compounds are well-known magnetocaloric materials, which show a pronounced negative thermal expansion (NTE) around the Curie temperature but have not been considered as NTE materials for industrial applications. The NaZn13-type LaFe13-xSix and LaFe11.5-xCoxSi1.5 compounds were synthesized, and their linear NTE properties were investigated. By optimizing the chemical composition, the sharp volume change in La(Fe, Si)13-based compounds was successfully modified into continuous expansion. By increasing the amount of Co dopant in LaFe11.5-xCoxSi1.5, the NTE shifts toward a higher temperature region, and also the NTE operation-temperature window becomes broader. Typically, the linear NTE coefficient identified in the LaFe10.5Co1.0Si1.5 compound reaches as much as -26.1 × 10(-6) K(-1), with an operation-temperature window of 110 K from 240 to 350 K, which includes room temperature. Such control of the specific composition and the NTE properties of La(Fe, Si)13-based compounds suggests their potential application as NTE materials.

  4. Crystal structure and magnetism of layered perovskites compound EuBaCuFeO5

    Science.gov (United States)

    Lal, Surender; Mukherjee, K.; Yadav, C. S.

    2018-04-01

    Layered perovskite compounds have interesting multiferroic properties.YBaCuFeO5 is one of the layered perovskite compounds which have magnetic and dielectric transition above 200 K. The multiferroic properties can be tuned with the replacement of Y with some other rare earth ions. In this manuscript, structural and magnetic properties of layered perovskite compound EuBaCuFeO5 have been investigated. This compound crystallizes in the tetragonal structure with P4mm space group and is iso-structural with YBaCuFeO5. The magnetic transition has been found to shift to 120 K as compared to YBaCuFeO5 which has the transition at 200 K. This shift in the magnetic transition has been ascribed to the decrease in the chemical pressure that relaxes the magnetic moments.

  5. Coexistence of magnetism and superconductivity in the hole doped FeAs-based superconducting compound

    International Nuclear Information System (INIS)

    Lu, T.P.; Wu, C.C.; Chou, W.H.; Lan, M.D.

    2010-01-01

    The magnetic and superconducting properties of the Sm-doped FeAs-based superconducting compound were investigated under wide ranges of temperature and magnetic field. After the systematical magnetic ion substitution, the superconducting transition temperature decreases with increasing magnetic moment. The hysteresis loop of the La 0.87-x Sm x Sr 0.13 FeAsO sample shows a superconducting hysteresis and a paramagnetic background signal. The paramagnetic signal is mainly attributed to the Sm moments. The experiment demonstrates that the coexistence of magnetism and superconductivity in the hole doped FeAs-based superconducting compounds is possible. Unlike the electron doped FeAs-based superconducting compounds SmFeAsOF, the hole doped superconductivity is degraded by the substitution of La by Sm. The hole-doped and electron-doped sides are not symmetric.

  6. Spin correlations in (Mn,Fe)2(P,Si) magnetocaloric compounds above Curie temperature

    NARCIS (Netherlands)

    Miao, X.F.; Caron, L.; Gubbens, P.C.M.; Yaouanc, A; Dalmas de Réotier, P; Luetkens, H.; Amato, A; van Dijk, N.H.; Brück, E.H.

    2016-01-01

    The longitudinal-field muon-spin relaxation (LF-μSR) technique was employed to study the spin correlations in (Mn,Fe)2(P,Si) compounds above the ferromagnetic transition temperature (TC). The (Mn,Fe)2(P,Si) compound under study is found to show itinerant magnetism. The standard deviation of the

  7. Magnetocaloric effects in Mn1.35Fe0.65P1−xSix compounds

    International Nuclear Information System (INIS)

    Geng Yao-Xiang; Tegus O; Bi Li-Ge

    2012-01-01

    The structural and magnetocaloric properties of Mn 1.35 Fe 0.65 P 1−x Si x compounds are investigated. The Si-substituted compounds, Mn 1.35 Fe 0.65 P 1−x Si x with x = 0.52, 0.54, 0.55, 0.56, and 0.57, are prepared by high-energy ball milling and the solid-state reaction. The X-ray diffraction shows that the compounds crystallize into the Fe 2 P-type hexagonal structure with space group P6-bar2m. The magnetic measurements show that the Curie temperature of the compound increases from 253 K for x = 0.52 to 296 K for x = 0.56. The isothermal magnetic-entropy change of the Mn 1.35 Fe 0.65 P 1−x Si x compound decreases with the Si content increasing. The maximal value of the magnetic-entropy change is about 7.0 J/kg·K in the Mn 1.35 Fe 0.65 P 0.48 Si 0.52 compound with a field change of 1.5 T. The compound quenched in water possesses a larger magnetic entropy change and a smaller thermal hysteresis than the non-quenched samples. The thermal hysteresis of the compound is less than 3.5 K. The maximum adiabatic temperature change is about 1.4 K in the Mn 1.35 Fe 0.65 P 0.45 Si 0.55 compound with a field change of 1.48 T. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  8. Phase-Transition and Magnetic Moment of the Gd3+ Ion in the Gd2Fe17 Compound

    Institute of Scientific and Technical Information of China (English)

    HAO Yan-Ming; FU Bin; ZHOU Yan; ZHAO Miao

    2009-01-01

    The structure and magnetic phase transitions of the Gd2Fe17 compound are investigated by using a differential thermal/thermogravimetric analyzer, x-ray diffraction, and magnetization measurements. The result shows that there are two phase structures for the Gd2Fe17 compound: the hexagonal Th2Ni17-type structure at high tem-peratures (above 1243℃), and the rhombohedrai Th2Zn17-type structure, respectively. A method to measure the magnetic moments of the Gd-sublattice and the Fe-sublattice in the Gd2Fe17 compound is presented. The moments of the Gd-sublattice and the Fe-sublattice in the Gd2Fe17 compound from 77 to 500 K are measured in this way with a vibrating sample magnetometer. A detailed discussion is presented.

  9. Fabrication of FeSi and Fe{sub 3}Si compounds by electron beam induced mixing of [Fe/Si]{sub 2} and [Fe{sub 3}/Si]{sub 2} multilayers grown by focused electron beam induced deposition

    Energy Technology Data Exchange (ETDEWEB)

    Porrati, F.; Sachser, R.; Huth, M. [Physikalisches Institut, Goethe-Universität, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany); Gazzadi, G. C. [S3 Center, Nanoscience Institute-CNR, Via Campi 213/a, 41125 Modena (Italy); Frabboni, S. [S3 Center, Nanoscience Institute-CNR, Via Campi 213/a, 41125 Modena (Italy); FIM Department, University of Modena and Reggio Emilia, Via G. Campi 213/a, 41125 Modena (Italy)

    2016-06-21

    Fe-Si binary compounds have been fabricated by focused electron beam induced deposition by the alternating use of iron pentacarbonyl, Fe(CO){sub 5}, and neopentasilane, Si{sub 5}H{sub 12} as precursor gases. The fabrication procedure consisted in preparing multilayer structures which were treated by low-energy electron irradiation and annealing to induce atomic species intermixing. In this way, we are able to fabricate FeSi and Fe{sub 3}Si binary compounds from [Fe/Si]{sub 2} and [Fe{sub 3}/Si]{sub 2} multilayers, as shown by transmission electron microscopy investigations. This fabrication procedure is useful to obtain nanostructured binary alloys from precursors which compete for adsorption sites during growth and, therefore, cannot be used simultaneously.

  10. Obtention of the TiFe compound by high-energy milling of Ti+Fe and TiH{sub 2}+Fe powder mixtures; Obtencao do composto TiFe a partir da moagem de alta energia de misturas Ti+Fe e TiH{sub 2}+Fe

    Energy Technology Data Exchange (ETDEWEB)

    Falcao, R.B.; Dammann, E.D.C.C.; Rocha, C.J.; Leal Neto, R.M., E-mail: railson.falcao@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencias e Tecnologia de Materiais. Lab. de Intermetalicos

    2010-07-01

    In this work TiFe compound was obtained by two process routes involving high-energy ball milling: mechanical alloying from Ti and Fe powders (route 1) and mechanical milling from TiH{sub 2} and Fe powders, both followed by an annealing heat treatment. Shaker and planetary ball mills were utilized for times varying from 1-25 hours. Milled and annealed powders were characterized by SEM and X-ray diffraction analyses. TiFe compound was formed in both routes. A strong powder adherence in the milling vial and balls occurred with route 1 in both mills. Powder adherence was significantly reduced by using TiH{sub 2} (route 2) mainly in the planetary mill, in spite of TiFe formation has only occurred after the annealing treatment. (author)

  11. Solid-solution stability and preferential site-occupancy in (R-R')2Fe14B compounds

    Science.gov (United States)

    Colin, C. V.; Ito, M.; Yano, M.; Dempsey, N. M.; Suard, E.; Givord, D.

    2016-06-01

    The rare-earth (R) uniaxial anisotropy of R2Fe14B compounds with magnetic R atoms (e.g., Nd or Pr) is at the origin of the exceptional hard magnetic properties achieved in magnets based on these compounds. The uniaxial anisotropy found in Ce2Fe14B is attributed mainly to the magnetism of Fe. Ce is the most abundant R element and there has been much recent effort to fabricate magnets in which Ce is partially substituted for Nd. In the present neutron study of (R1-xCex)2Fe14B (R = La or Nd), Ce is found to enter the R2Fe14B phase over the entire composition range. The crystallographic parameters decrease with increasing Ce content and the Ce atoms preferentially occupy the smaller 4f sites. It is concluded that Ce in these (RR')2Fe14B compounds essentially maintains the intermediate valence character found in Ce2Fe14B. It is proposed that, in this intermediate valence state, Ce weakly contributes to uniaxial anisotropy, thus making a link with the fact that significant coercivity is preserved in Ce-substituted NdFeB magnets.

  12. Solid-solution stability and preferential site-occupancy in (R-R′)2Fe14B compounds

    International Nuclear Information System (INIS)

    Colin, C. V.; Dempsey, N. M.; Ito, M.; Yano, M.; Suard, E.; Givord, D.

    2016-01-01

    The rare-earth (R) uniaxial anisotropy of R 2 Fe 14 B compounds with magnetic R atoms (e.g., Nd or Pr) is at the origin of the exceptional hard magnetic properties achieved in magnets based on these compounds. The uniaxial anisotropy found in Ce 2 Fe 14 B is attributed mainly to the magnetism of Fe. Ce is the most abundant R element and there has been much recent effort to fabricate magnets in which Ce is partially substituted for Nd. In the present neutron study of (R 1−x Ce x ) 2 Fe 14 B (R = La or Nd), Ce is found to enter the R 2 Fe 14 B phase over the entire composition range. The crystallographic parameters decrease with increasing Ce content and the Ce atoms preferentially occupy the smaller 4f sites. It is concluded that Ce in these (RR′) 2 Fe 14 B compounds essentially maintains the intermediate valence character found in Ce 2 Fe 14 B. It is proposed that, in this intermediate valence state, Ce weakly contributes to uniaxial anisotropy, thus making a link with the fact that significant coercivity is preserved in Ce-substituted NdFeB magnets.

  13. μ4-Orthothio­carbonato-tetra­kis­[tri­carbonyl­iron(I)](2 Fe—Fe)

    Science.gov (United States)

    Shi, Yao-Cheng; Cheng, Huan-Ren; Yuan, Li-Min; Li, Qian-Kun

    2011-01-01

    The fused bis-butterfly-shaped title compound, [Fe4(CS4)(CO)12], possesses an orthothio­carbonate (CS4 4−) ligand that acts as a bridge between two Fe2(CO)6 units. A short intra­molecular S⋯S contact [2.6984 (8) and 2.6977 (8) Å] occurs in each S2Fe2(CO)6 fragment. PMID:22219779

  14. First-principles calculations of two cubic fluoropervskite compounds: RbFeF3 and RbNiF3

    International Nuclear Information System (INIS)

    Mubarak, A.A.; Al-Omari, Saleh

    2015-01-01

    We present first-principles calculations of the structural, elastic, electronic, magnetic and optical properties for RbFeF 3 and RbNiF 3 . The full-potential linear augmented plan wave (FP-LAPW) method within the density functional theory was utilized to perform the present calculations. We employed the generalized gradient approximation as exchange-correlation potential. It was found that the calculated analytical lattice parameters agree with previous studies. The analysis of elastic constants showed that the present compounds are elastically stable and anisotropic. Moreover, both compounds are classified as a ductile compound. The calculations of the band structure and density functional theory revealed that the RbFeF 3 compound has a half-metallic behavior while the RbNiF 3 compound has a semiconductor behavior with indirect (M–Γ) band gap. The ferromagnetic behavior was studied for both compounds. The optical properties were calculated for the radiation of up to 40 eV. A beneficial optics technology is predicted as revealed from the optical spectra. - Highlights: • RbFeF 3 and RbNiCl 3 compounds are elastically stable. • RbFeF 3 and RbNiCl 3 compounds are classified as a ductile compound. • The RbFeF 3 compound has a half-metallic behavior while the RbNiF 3 compound has a semiconductor behavior. • The optical properties were calculated for the radiation of up to 40 eV

  15. Spin reorientation and giant low-temperature magnetostriction of polycrystalline NdFe1.9 compound

    Science.gov (United States)

    Tang, Y. M.; He, Y.; Huang, Y.; Zhang, L.; Tang, S. L.; Du, Y. W.

    2018-04-01

    The spin reorientation and magnetostriction of polycrystalline NdFe1.9 cubic Laves phase compound were investigated. A prominent transition from tetragonal symmetry to orthorhombic symmetry in NdFe1.9 compound was determined by X-ray crystallographic study. Meanwhile, a large spontaneous magnetostriction λ111 of ∼3100 ppm was detected at 15 K, which is larger than the theoretical value of 2000 ppm predicted by single-ion model. NdFe1.9 exhibits larger low-field magnetostriction than PrFe1.9 and TbFe1.9 at 5 K in the magnetic field range of H ≤ 13 kOe, which makes it a promising material for low-temperature applications. The present work might be helpful to discover inexpensive Nd-based high-performance magnetostrictive and even magnetoelectric materials for low-temperature applications.

  16. Magnetic properties of the HoMn6-xFe xSn6 compounds

    International Nuclear Information System (INIS)

    Cakir, O.; Dincer, I.; Duman, E.; Krenke, T.; Elmali, A.; Elerman, Y.

    2007-01-01

    Intermetallic compounds of HoMn 6-x Fe x Sn 6 (0 ≤ x ≤ 1.2) were studied by means of field-cooled (FC) and zero-field-cooled (ZFC) magnetization measurements in the temperature range 5 K ≤ T ≤ 600 K. The unit cell parameters decrease with the increasing of Fe content. The compounds with x = 0 and 0.3 behave ferrimagnetically in the whole temperature range and spin reorientation transition is observed at 200 and 185 K, respectively. The x = 0.5 and 0.6 compounds show ferrimagnetic-helimagnetic-ferrimagnetic phase transitions with decreasing temperature while the compounds with x = 0.9 and 1.2 only show helimagnetic-ferrimagnetic phase transitions. Additionally, for the x = 0.6 compound the metamagnetic phase transition from helimagnetism to ferrimagnetism is induced by an applied field 20 kOe

  17. Decacarbonyl[μ4-(ethane-1,2-diyldinitrilotetrakis(methanethiolato]bis(triphenylphosphanetetrairon(2 Fe—Fe

    Directory of Open Access Journals (Sweden)

    Wei-Ming Gao

    2012-02-01

    Full Text Available In the title compound, [Fe4(C6H12N2S4(C18H15P2(CO10], the unit cell contains one molecule, which exhibits a crystallographically imposed center of symmetry. The independent Fe2S2 fragment [Fe—Fe = 2.527 (1 Å] is in a butterfly conformation, and each Fe atom displays a pseudo-square-pyramidal coordination geometry. The phosphane group occupies an apical position [Fe—P = 2.2670 (14 Å]. In the crystal, weak intermolecular C—H...O hydrogen bonds link the molecules into chains along [110].

  18. Moessbauer spectra of some complex compounds of Fe(II) with pyridine

    International Nuclear Information System (INIS)

    Teodorescu, M.; Filoti, G.

    1975-01-01

    The Moessbauer spectra of [Fe(II)py 6 ]Br 2 at 298 and 80 K and the reflectance spectra of the same compound at room temperature are presented. Isomer shift and quadrupole splitting were determined for [Fe(II)py 6 ]Br 2 at 298 and 80 K, their values being correlated with those obtained from electronic spectra measured in the solid state. (Z.S.)

  19. Effect of Co on Si and Fe-containing intermetallic compounds (IMCs) in Al-20Si-5Fe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Fatih Kilicaslan, M. [Department of Physics, Faculty of Art and Science, Kastamonu University, Kastamonu (Turkey); Yilmaz, Fikret [Department of Physics, Faculty of Art and Science, Gaziosmanpasa University, Tokat (Turkey); Hong, Soon-Jik, E-mail: hongsj@kongju.ac.kr [Division of Advanced Materials Engineering, Institute for Rare Metals, Kongju National University, Cheonan 331717 (Korea, Republic of); Uzun, Orhan, E-mail: orhan.uzun@gop.edu.tr [Department of Physics, Faculty of Art and Science, Gaziosmanpasa University, Tokat (Turkey)

    2012-10-30

    The effects of cobalt addition on microstructure and mechanical properties of Al-20Si-5Fe-XCo (X=0, 1, 3, and 5) alloys were reported in this study. The alloys were produced by both conventional sand casting and melt-spinning at 20 m/s disk velocity. Microstructures of the samples were investigated using X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Vickers micro-hardness tester was used for hardness measurements. Results showed that Co addition can alter morphology of Fe-bearing intermetallic compounds (IMCs) from long rod/needle-like structures to short rod-like ones, and lead to a more homogenous distribution in the microstructure. Addition of 5 wt% Co leads to a decrease in average size of the primary silicon phases in as-cast Al-Si alloys. In melt-spun alloys, with the addition of Co, the microstructure became finer and more homogenously distributed, while thickness of the featureless zone has seen great increase. The optimum Fe to Co ratio was found to be 1 for suppressing the undesirable effect of Fe-bearing acicular/needle-like intermetallic compounds.

  20. Ferroelectric and magnetic properties in high-pressure synthesized BiFeO3 compound

    International Nuclear Information System (INIS)

    Zhai, L.; Shi, Y.G.; Gao, J.L.; Tang, S.L.; Du, Y.W.

    2011-01-01

    Highlights: → A high-density polycrystalline BiFeO 3 compound was synthesized by high-pressure annealing method. → The sample showed weak ferromagnetic at room temperature, which could be attributed to the lattice distortion induced by the high-pressure annealing. → Irregular domains were observed on the surface of the sample by piezoresponse force microscopy, and a typical hysteresis loop was obtained. - Abstract: High-density polycrystalline BiFeO 3 compound was synthesized by high-pressure annealing. Measurements of crystal structure, magnetic, and ferroelectric properties were made on the sample. It was found that the sample was almost single phase with a distorted R3c structure. The results of the X-ray photoelectron spectra demonstrate that the oxidation state of Fe in the sample is Fe 3+ . The room-temperature field dependence of magnetization for BiFeO 3 exhibits a hysteretic behavior. The observed weak ferromagnetism could be ascribed to the lattice distortion induced by the high-pressure annealing. In addition, the local ferroelectric performance of the sample was studied by piezoresponse force microscopy.

  1. Structural, hyperfine and Raman properties of RE2FeSbO7 compounds

    International Nuclear Information System (INIS)

    Berndt, G.; Silva, K.L.; Ivashita, F.F.; Paesano, A.; Blanco, M.C.; Miner, E.V.P.; Carbonio, R.E.; Dantas, S.M.; Ayala, A.P.; Isnard, O.

    2015-01-01

    Highlights: • We prepared monophasic RE 2 FeSbO 7 pyrochlores. • RE 2 FeSbO 7 compounds were characterized regarding crystallographic, vibrational and hyperfine properties. • We find out that a site disorder takes place for the RE’s of larger ionic radii. • Lattice parameters, Raman bands and quadrupole splittings were shown to depend correlatedly on the RE ionic radius. - Abstract: Pyrochlores of the RE 2 FeSbO 7 type were synthesized by ball-milling followed by annealing in free atmosphere at high temperatures. The samples prepared were characterized by X-ray diffraction, Raman spectroscopy and 57 Fe Mössbauer spectroscopy, at room temperature. The results showed that RE 2 FeSbO 7 compounds have a cubic structure, i.e., Fd-3m (#227) space group, and that a site disorder takes place for the RE’s of larger ionic radii. Lattice parameters, Raman bands and quadrupole splittings were shown to depend correlatedly on the RE ionic radius. This behavior is discussed in terms of the pyrochlore crystallographic structure

  2. Phase transitions and magnetocaloric effects in intermetallic compounds MnFeX (X=P, As, Si, Ge)

    International Nuclear Information System (INIS)

    Tegus, O.; Bao Li-Hong; Song Lin

    2013-01-01

    Since the discovery of giant magnetocaloric effect in MnFeP 1−x As x compounds, much valuable work has been performed to develop and improve Fe 2 P-type transition-metal-based magnetic refrigerants. In this article, the recent progress of our studies on fundamental aspects of theoretical considerations and experimental techniques, effects of atomic substitution on the magnetism and magnetocalorics of Fe 2 P-type intermetallic compounds MnFeX (X=P, As, Ge, Si) is reviewed. Substituting Si (or Ge) for As leads to an As-free new magnetic material MnFeP 1−x Si(Ge) x . These new materials show large magnetocaloric effects resembling MnFe(P, As) near room temperature. Some new physical phenomena, such as huge thermal hysteresis and ‘virgin’ effect, were found in new materials. On the basis of Landau theory, a theoretical model was developed for studying the mechanism of phase transition in these materials. Our studies reveal that MnFe(P, Si) compound is a very promising material for room-temperature magnetic refrigeration and thermo-magnetic power generation. (topical review - magnetism, magnetic materials, and interdisciplinary research)

  3. Calculations of the magnetic properties of R2M14B intermetallic compounds (R=rare earth, M=Fe, Co)

    International Nuclear Information System (INIS)

    Ito, Masaaki; Yano, Masao; Dempsey, Nora M.; Givord, Dominique

    2016-01-01

    The hard magnetic properties of “R–M–B” (R=rare earth, M=mainly Fe) magnets derive from the specific intrinsic magnetic properties encountered in Fe-rich R 2 M 14 B compounds. Exchange interactions are dominated by the 3d elements, Fe and Co, and may be modeled at the macroscopic scale with good accuracy. Based on classical formulae that relate the anisotropy coefficients to the crystalline electric field parameters and exchange interactions, a simple numerical approach is used to derive the temperature dependence of anisotropy in various R 2 Fe 14 B compounds (R=Pr, Nd, Dy). Remarkably, a unique set of crystal field parameters give fair agreement with the experimentally measured properties of all compounds. This implies reciprocally that the properties of compounds that incorporate a mixture of different rare-earth elements may be predicted accurately. This is of special interest for material optimization that often involves the partial replacement of Nd with another R element and also the substitution of Co for Fe. - Highlights: • Anisotropy constants derived from CEF parameters of R 2 M 14 B compounds (M=Fe, Co). • Anisotropy constants of all R 2 Fe 14 B compounds using unique set of CEF parameters. • Moment non-collinearity in magnetization processes under B app along hard axis.

  4. Magnetic properties and magnetocaloric effects in Mn1.2Fe0.8P1-xGex compounds

    International Nuclear Information System (INIS)

    Ou, Z Q; Wang, G F; Lin Song; Tegus, O; Brueck, E; Buschow, K H J

    2006-01-01

    We have studied the magnetic properties and magnetocaloric effects in the Mn 1.2 Fe 0.8 P 1-x Ge x compounds with x = 0.2, 0.22, 0.3, 0.4 and 0.5. X-ray diffraction patterns show that the Mn 1.2 Fe 0.8 P 1-x Ge x compounds crystallize in the hexagonal Fe 2 P-type crystal structure. The magnetic moments of the Mn 1.2 Fe 0.8 P 1-x Ge x compounds measured at 5 K and 5 T increase with increasing Ge content. The Curie temperature increases strongly and the magnetic entropy change has a maximum around 233 K for the compound with x = 0.22, which is about 19 and 31 J kg -1 K -1 for a field change of 2 and 5 T, respectively

  5. Crystal structure and magnetic properties of a nitrogenated melt-spun Sm[sub 2]Fe[sub 17] compound

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Choong-Jin [Electromagnetic Materials Laboratory, Research Institute of Industrial Science and Technology, P.O. Box 135, 790-330 Pohang (Korea, Republic of); Lee, Woo-Young [Electromagnetic Materials Laboratory, Research Institute of Industrial Science and Technology, P.O. Box 135, 790-330 Pohang (Korea, Republic of); Choi, Seung-Duck [Electromagnetic Materials Laboratory, Research Institute of Industrial Science and Technology, P.O. Box 135, 790-330 Pohang (Korea, Republic of)

    1994-05-15

    Sm[sub 2]Fe[sub 17]N[sub 2.9] compound powders were prepared from parent alloys of Sm[sub 2]Fe[sub 17] which were made by both arc melting and rapid solidification processes. The cast Sm[sub 2]Fe[sub 17] contained mixed phases of SmFe[sub 3] and [alpha]-Fe, and correspondingly formed less Sm[sub 2]Fe[sub 17]N[sub x] with a rather large amount of residual [alpha]-Fe after nitrogenation. The melt-spun Sm[sub 2]Fe[sub 17] compound, however, was single phase and exhibited a negligible amount of residual [alpha]+Fe after nitrogenation. The residual amount of free iron was found to increase as a function of milling time and to impede the development of promising permanent magnetic properties. The melt-spun Sm[sub 2]Fe[sub 17]N[sub x] compound powders exhibited a coercivity value [sub i]H[sub c] of 5 kOe, which is double that of the as-cast Sm[sub 2]Fe[sub 17]N[sub x] powders and a high remanence B[sub r]=60 e.m.u. g[sup -1]. The average magnetic moment of Fe atoms in the crystal is estimated to be 2.29 [mu][sub B] and the Fe atom in the 6c site exhibits the highest magnetic moment of 2.65 [mu][sub B]. The expansion in the c axial direction of the nitrogenated crystal was found to be mainly due to extension of Sm(6c)-Fe(c) and Fe(18f)-Fe(18f) distances. ((orig.))

  6. Influence of the substitution of Ni for Fe on the microstructure evolution and magnetic phase transition in La(Fe1−xNix)11.5Si1.5 compounds

    International Nuclear Information System (INIS)

    Sun, Song; Ye, Rongchang; Long, Yi

    2013-01-01

    Graphical abstract: M–T curves show that all the compounds undergo a ferromagnetic–paramagnetic magnetic phase transition process. Besides, the Curie temperature T c of La(Fe 1−x Ni x ) 11.5 Si 1.5 (x = 0, 0.01, 0.02, 0.03) compounds increase monotonously from 195 K to 219 K when Ni content x varies from 0 to 0.03. Highlights: ► We substituted Fe by new element Ni in La(Fe 1−x Ni x ) 11.5 Si 1.5 compounds. ► The microstructure evolution, magnetic phase transition and Curie temperature of La(Fe 1−x Ni x ) 11.5 Si 1.5 compounds were investigated. ► The small substitution of Ni for Fe in La(Fe 1−x Ni x ) 11.5 Si 1.5 compounds enhances the formation of 1:13 phase and helps the elimination of impurity phase significantly. ► The Curie temperature T C of La(Fe 1−x Ni x ) 11.5 Si 1.5 compounds increase monotonously from 195 K to 219 K when x varies from 0 to 0.03. - Abstract: The influence of Ni substitution on the microstructure evolution and magnetic phase transition has been investigated in La(Fe 1−x Ni x ) 11.5 Si 1.5 (x = 0, 0.01, 0.02, 0.03) compounds. Results show that partial substitution of Ni for Fe in La(Fe 1−x Ni x ) 11.5 Si 1.5 (x = 0, 0.01, 0.02, 0.03) alloys promotes fining of the as-cast microstructure. Besides, the formation of 1:13 phase and the elimination of impurity phases is facilitated significantly when annealed at 1373 K for 5 days. Large amounts of inhomogeneities are present in the annealed LaFe 11.5 Si 1.5 alloy. While almost single 1:13 phase is obtained in La(Fe 1−x Ni x ) 11.5 Si 1.5 (x = 0.02, 0.03) alloys. Moreover, the Curie temperature T C of La(Fe 1−x Ni x ) 11.5 Si 1.5 (x = 0, 0.01, 0.02, 0.03) compounds increase monotonously from 195 K to 219 K when Ni content x varies from 0 to 0.03.

  7. NMR measurements in milled RE-TM2 compounds (RE=Gd and TM=Co, Fe)

    International Nuclear Information System (INIS)

    Tribuzy, C.V.; Guimaraes, A.P.; Biondo, A.; Larica, C.; Alves, K.M.B.

    1996-09-01

    Milled samples of the Laves phase intermetallic compounds Gd Fe 2 and Gd CO 2 were measured by NMR at 4.2 K. The milling was made from the crystalline intermetallic compounds, inside a cylindrical tool made of hard steel, under argon atmosphere, for several different time intervals. The initial compounds were produced from high purity elements in an arc furnace, under inert atmosphere. Their X-ray diffraction patterns agreed with those of the literature. The milling of Gd Fe 2 and of Gd CO 2 , induces amorphization. Above 1 hour the milling of Gd Fe 2 leads to segregation of α-Fe and formation of a Gd-Fe phase. These results are shown in the X-ray analysis. The spin-echo pulse NMR technique was utilized to study some structural and magnetic as a function of milling time. The measurements were made in a broad band pulse NMR spectrometer. The NMR spectra of the 155 Gd 157 Gd isotopes in Gd Fe 2 show a broadening and displacement of the NMR lines, reflecting the introduction of defects, some kind of disorder and also the formation of a new Gd-rich phase after 1 hour. This result is in agreement with the X-ray spectra. In both systems, the spectra of the amorphous samples show broader lines, and the measured hyperfine fields do not change much with milling. (author). 9 refs., 4 figs

  8. Synthesis and characterization of Fe-Ti-Sb intermetallic compounds: Discovery of a new Slater-Pauling phase

    Science.gov (United States)

    Naghibolashrafi, N.; Keshavarz, S.; Hegde, Vinay I.; Gupta, A.; Butler, W. H.; Romero, J.; Munira, K.; LeClair, P.; Mazumdar, D.; Ma, J.; Ghosh, A. W.; Wolverton, C.

    2016-03-01

    Compounds of Fe, Ti, and Sb were prepared using arc melting and vacuum annealing. Fe2TiSb , expected to be a full Heusler compound crystallizing in the L 21 structure, was shown by XRD and SEM analyses to be composed of weakly magnetic grains of nominal composition Fe1.5TiSb with iron-rich precipitates in the grain boundaries. FeTiSb, a composition consistent with the formation of a half-Heusler compound, also decomposed into Fe1.5TiSb grains with Ti-Sb rich precipitates and was weakly magnetic. The dominant Fe1.5TiSb phase appears to crystallize in a defective L 21 -like structure with iron vacancies. Based on this finding, a first-principles DFT-based binary cluster expansion of Fe and vacancies on the Fe sublattice of the L 21 structure was performed. Using the cluster expansion, we computationally scanned >103 configurations and predict a novel, stable, nonmagnetic semiconductor phase to be the zero-temperature ground state. This new structure is an ordered arrangement of Fe and vacancies, belonging to the space group R 3 m , with composition Fe1.5TiSb , i.e., between the full- and half-Heusler compositions. This phase can be visualized as alternate layers of L 21 phase Fe2TiSb and C 1b phase FeTiSb, with layering along the [111] direction of the original cubic phases. Our experimental results on annealed samples support this predicted ground-state composition, but further work is required to confirm that the R 3 m structure is the ground state.

  9. Phase relation of LaFe11· 6Si1· 4 compounds annealed at different ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 35; Issue 2. Phase relation of LaFe11.6Si1.4 compounds annealed at different high-temperature and the magnetic property of LaFe11.6−CoSi1.4 compounds. Xiang Chen Yungui Chen Yongbai Tang. Volume 35 Issue 2 April 2012 pp 175-182 ...

  10. High field magnetization process of (Sm, Nd)2Fe17Ny compounds

    International Nuclear Information System (INIS)

    Yu, M.J.; Tang, N.; Liu, Y.L.; Tegus, O.; Lu, Y.; Kuang, J.P.; Yang, F.M.; Li, X.; Zhou, G.F.; Boer, F.R. de

    1992-01-01

    The crystal structure and high-field magnetization process of (Sm 1-x Nd x ) 2 Fe 17 N y compounds (x = 0.0, 0.1, ..., 1.0, 2 1-x Nd x ) 2 Fe 17 N y compounds were found to crystallize in the rhombohedral Th 2 Zn 17 structure. As x increases, the Curie temperature decreases. The anisotropy fields and easy magnetization direction were investigated from 1.5 K to room temperature by means of high-field magnetization measurements and AC-susceptibility measurements, combined with X-ray diffraction on random and magnetically aligned powder samples. The anisotropy field decreases with increasing x and approaches a minimum value at about x = 0.6, then increases again. A tentative spin phase diagram for the (Sm 1-x Nd x ) 2 Fe 17 N y series is presented. At room temperature, the easy magnetization direction remains along the c-axis up to x = 0.6. (orig.)

  11. Crystalline and Electronic Structures and Magnetic and Electrical Properties of La-Doped Ca2Fe2O5 Compounds

    Science.gov (United States)

    Phan, T. L.; Tho, P. T.; Tran, N.; Kim, D. H.; Lee, B. W.; Yang, D. S.; Thiet, D. V.; Cho, S. L.

    2018-01-01

    Brownmillerite Ca2Fe2O5 has been observed to exhibit many outstanding properties that are applicable to ecotechnology. However, very little work on doped Ca2Fe2O5 compounds has been carried out to widen their application scope. We present herein a detailed study of the crystalline/geometric and electronic structures and magnetic and electrical properties of Ca2- x La x Fe2O5 ( x = 0 to 1) prepared by conventional solid-state reaction. X-ray diffraction patterns indicated that the compounds with x = 0 to 0.05 exhibited brownmillerite-type single phase. La doping with higher content ( x ≥ 0.1) stimulated additive formation of Grenier- (LaCa2Fe3O8) and perovskite-type (LaFeO3) phases. Extended x-ray absorption fine structure spectroscopy at the Fe K-edge and electron spin resonance spectroscopy revealed presence of Fe3+ in the parent Ca2Fe2O5 ( x = 0) and both Fe3+ and Fe4+ in the doped compounds ( x ≥ 0.05). The Fe4+ content tended to increase with increasing x. This stimulates ferromagnetic exchange interactions between Fe3+ and Fe4+ ions and directly influences the magnetic properties of Ca2- x La x Fe2O5. Electrical resistivity ( ρ) measurements in the temperature range of T = 20 K to 400 K revealed that all the compounds exhibit insulator behavior; the ρ( T) data for x ≥ 0.1 could be described based on the adiabatic small polaron hopping model.

  12. Solid-solution stability and preferential site-occupancy in (R-R′){sub 2}Fe{sub 14}B compounds

    Energy Technology Data Exchange (ETDEWEB)

    Colin, C. V.; Dempsey, N. M. [CNRS, Inst NEEL, F-38000 Grenoble (France); Univ. Grenoble Alpes, Inst NEEL, F-38000 Grenoble (France); Ito, M. [CNRS, Inst NEEL, F-38000 Grenoble (France); Univ. Grenoble Alpes, Inst NEEL, F-38000 Grenoble (France); Advanced Material Engineering Div., Toyota Motor Corporation, Susono 410-1193 (Japan); Yano, M. [Advanced Material Engineering Div., Toyota Motor Corporation, Susono 410-1193 (Japan); Suard, E. [Institut Laue-Langevin, CS 20156-38042 Grenoble cedex 9 (France); Givord, D. [CNRS, Inst NEEL, F-38000 Grenoble (France); Univ. Grenoble Alpes, Inst NEEL, F-38000 Grenoble (France); Instituto de Fisica, Universidade Federal do Rio de Janeiro, 21941-972 Rio de Janeiro (Brazil)

    2016-06-13

    The rare-earth (R) uniaxial anisotropy of R{sub 2}Fe{sub 14}B compounds with magnetic R atoms (e.g., Nd or Pr) is at the origin of the exceptional hard magnetic properties achieved in magnets based on these compounds. The uniaxial anisotropy found in Ce{sub 2}Fe{sub 14}B is attributed mainly to the magnetism of Fe. Ce is the most abundant R element and there has been much recent effort to fabricate magnets in which Ce is partially substituted for Nd. In the present neutron study of (R{sub 1−x}Ce{sub x}){sub 2}Fe{sub 14}B (R = La or Nd), Ce is found to enter the R{sub 2}Fe{sub 14}B phase over the entire composition range. The crystallographic parameters decrease with increasing Ce content and the Ce atoms preferentially occupy the smaller 4f sites. It is concluded that Ce in these (RR′){sub 2}Fe{sub 14}B compounds essentially maintains the intermediate valence character found in Ce{sub 2}Fe{sub 14}B. It is proposed that, in this intermediate valence state, Ce weakly contributes to uniaxial anisotropy, thus making a link with the fact that significant coercivity is preserved in Ce-substituted NdFeB magnets.

  13. Combined effects of ultrasonic vibration and manganese on Fe-containing inter-metallic compounds and mechanical properties of Al-17Si alloy with 3wt.%Fe

    Directory of Open Access Journals (Sweden)

    Lin Chong

    2013-05-01

    Full Text Available The research studied the combined effects of ultrasonic vibration (USV and manganese on the Fe-containing inter-metallic compounds and mechanical properties of Al-17Si-3Fe-2Cu-1Ni (wt.% alloys. The results showed that, without USV, the alloys with 0.4wt.% Mn or 0.8wt.% Mn both contain a large amount of coarse plate-like δ-Al4(Fe,MnSi2 phase and long needle-like β-Al5(Fe,MnSi phase. When the Mn content changes from 0.4wt.% to 0.8wt.% in the alloys, the amount and the length of needle-like β-Al5(Fe,MnSi phase decrease and the plate-like δ-Al4(Fe,MnSi2 phase becomes much coarser. After USV treatment, the Fe-containing compounds in the alloys are refined and exist mainly as δ-Al4(Fe,MnSi2 particles with an average grain size of about 20 μm, and only a small amount of β-Al5(Fe,MnSi phase remains. With USV treatment, the ultimate tensile strengths (UTS of the alloys containing 0.4wt.%Mn and 0.8wt.%Mn at room temperature are 253 MPa and 262 MPa, respectively, and the ultimate tensile strengths at 350 °C are 129 MPa and 135 MPa, respectively. It is considered that the modified morphology and uniform distribution of the Fe-containing inter-metallic compounds, which are caused by the USV process, are the main reasons for the increase in the tensile strength of these two alloys.

  14. Effect of introduction atoms on effective exchange field in ferrimagnetic rare earth compounds and 3d-transition metal compounds such as R2Fe17 and RFe11Ti

    International Nuclear Information System (INIS)

    Nikitin, S.A.; Tereshina, I.S

    2003-01-01

    The magnetic properties of the ferrimagnetic compounds R 2 Fe 17 and RFe 11 Ti, as well as their hydrides and nitrides are studied. The change in the exchange fields, effecting the rare earth (RE) ions both from the side of the Fe sublattice and from the side of other RE ions in the process of hydrogenation and nitration is determined and Curie temperature dependence of the source compounds, their hydrides and nitrides on the de Genes factor is identified. It is established that in the course of the light atoms (H and N) introduction into the crystalline lattice of the R 2 Fe 17 and RFe 11 Ti compounds there takes place significant increase in the Curie temperature, in the Fe-Fe exchange interactions and decrease in the R-R interactions. This may be interpreted as the result of the oc curing changes in the electron structures of such compounds and indirect exchange interactions [ru

  15. Effect of Co on Si and Fe-containing intermetallic compounds (IMCs) in Al–20Si–5Fe alloys

    International Nuclear Information System (INIS)

    Fatih Kilicaslan, M.; Yilmaz, Fikret; Hong, Soon-Jik; Uzun, Orhan

    2012-01-01

    The effects of cobalt addition on microstructure and mechanical properties of Al–20Si–5Fe–XCo (X=0, 1, 3, and 5) alloys were reported in this study. The alloys were produced by both conventional sand casting and melt-spinning at 20 m/s disk velocity. Microstructures of the samples were investigated using X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Vickers micro-hardness tester was used for hardness measurements. Results showed that Co addition can alter morphology of Fe-bearing intermetallic compounds (IMCs) from long rod/needle-like structures to short rod-like ones, and lead to a more homogenous distribution in the microstructure. Addition of 5 wt% Co leads to a decrease in average size of the primary silicon phases in as-cast Al–Si alloys. In melt-spun alloys, with the addition of Co, the microstructure became finer and more homogenously distributed, while thickness of the featureless zone has seen great increase. The optimum Fe to Co ratio was found to be 1 for suppressing the undesirable effect of Fe-bearing acicular/needle-like intermetallic compounds.

  16. (CaFeAs){sub 10}Pt{sub z}As{sub 8} superconductors and related compounds

    Energy Technology Data Exchange (ETDEWEB)

    Stuerzer, Tobias

    2015-04-13

    The main topic of this dissertation is the identification of new compounds, structure determination, and substitution dependent investigation of properties in this new branch of the family of iron arsenide superconductors (Chapter 2). Chapter 2.1 presents the identification of the superconducting compounds and the corresponding structure elucidation identifying two dif-ferent species (CaFeAs){sub 10}Pt{sub 3}As{sub 8} and (CaFeAs){sub 10}Pt{sub 4}As{sub 8} in this family (abbreviated as 1038 and 1048 according to their stoichiometry). However, a closer look revealed a more challenging structure chemistry which is covered in Chapter 2.2. The following two Chapters 2.3 and 2.4 are devoted to (CaFeAs){sub 10}Pt{sub 3}As{sub 8} and more detailed investigations on this parent compound of the new superconductor family. Furthermore, transition metal substitution series (CaFe{sub 1-x}M{sub x}As){sub 10}Pt{sub 3}As{sub 8} were synthesized to investigate the resemblance to model systems Ba(Fe{sub 1-x}M{sub x}){sub 2}As{sub x} and LaO(Fe{sub 1-x}M{sub x})As in the scope of structural changes and superconductivity as described in Chapter 2.5. Initially amazing differences in superconducting properties com-paring 1038 and 1048 compounds are analyzed in Chapter 2.6 establishing an universal dop-ing model in the (CaFe{sub 1-x}M{sub x}As){sub 10}Pt{sub z}As{sub 8} family. Additionally substituent dependent properties upon rare earth substitution in electron doped (Ca{sub 1-y}RE{sub y}FeAs){sub 10}Pt{sub 3}As{sub 8} are investigated in Chapter 2.7, while a detailed study of superconducting properties and magnetism in (Ca{sub 1-y}La{sub y}FeAs){sub 10}Pt{sub 3}As{sub 8} by the local μSR technique is presented in Chapter 2.8. In Chapter 2.9 a comparison of direct and electron doping is discussed based on codoping experiments in (Ca{sub 1-y}La{sub y}Fe{sub 1-x}Pt{sub x}As){sub 10}Pt{sub 3}As{sub 8} and (CaFe{sub 1-x}Pt{sub x}As){sub 10}Pt{sub 4}As{sub 8}. Finally, in Chapter 2

  17. Thermal Expansion Anomaly and Spontaneous Magnetostriction of Y2Fe14Al3 Compound

    International Nuclear Information System (INIS)

    Yan-Ming, Hao; Xin-Yuan, Jiang; Chun-Jing, Gao; Yan-Zhao, Wu; Yan-Yan, Zhang

    2009-01-01

    The structure and magnetic properties of Y 2 Fe 14 Al 3 compound are investigated by means of x-ray diffraction and magnetization measurements. The Y 2 Fe 14 Al 3 compound has a hexagonal Th 2 Ni 17 -type structure. Negative thermal expansion is found in Y 2 Fe 14 Al 3 compound in the temperature range from 403 to 491K by x-ray dilatometry. The coefficient of the average thermal expansion is α-bar = –2.54 × 10 −5 K −1 . The spontaneous magnetostrictive deformations from 283 to 470K are calculated by means of the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation ω S decreases from 5.74 × 10 −3 to nearly zero with temperature increasing from 283 to 470 K, the spontaneous linear magnetostrictive deformation λ c along the c-axis is larger than the spontaneous linear magnetostrictive deformation λ a in basal-plane in the same temperature below 350 K

  18. Electronic, magnetic properties and phase diagrams of system with Fe4N compound: An ab initio calculations and Monte Carlo study

    Science.gov (United States)

    Masrour, R.; Jabar, A.; Hlil, E. K.

    2018-05-01

    Self-consistent ab initio calculations, based on Density Functional Theory (DFT) approach and using Full potential Linear Augmented Plane Wave (FLAPW) method, are performed to investigate the electronic and magnetic properties of the Fe4N compound. Polarized spin and spin-orbit coupling are included in calculations within the framework of the ferromagnetic state between Fe(I) and Fe(II) in Fe4N compound. We have used the obtained data from abinitio calculations as an input in Monte Carlo simulation to calculate the magnetic properties of this compounds such as the ground state phase diagrams, total and partial magnetization of Fe(I) and Fe(II) as well as the transition temperatures are computed. The variation of magnetization with the crystal field are also studied. The magnetic hysteresis cycle of the same Fe4N compound are determined for different values of temperatures and crystal field values. The two-step hysteresis loop are evidenced, which is typical for Fe4N structure. The ferromagnetic and superparamagnetic phase is observed as well.

  19. Crystal structure of a Ce2Fe2Mg15 compound

    International Nuclear Information System (INIS)

    Opainich, I.M.; Pavlyuk, V.V.; Bodak, O.I.

    1996-01-01

    A structure of a new Ce2Fe2Mg15 ternary compound (P63/mmc sp.gr., a=1.0324(5) nm, c=1.02080(4) nm) was determined by powder methods on a DRON-4.07 automatic diffractometer. The structure of a Ce2Fe2Mg15 crystal is a new variant of the ordered Th2Ni17 type superstructure, in which cerium atoms occupy the thorium positions; magnesium atoms occupy the nickel position 6g, 12k, and 12j; and iron atoms occupy the 4f position

  20. Effects of Fragmented Fe Intermetallic Compounds on Ductility in Al-Si-Mg Alloys.

    Science.gov (United States)

    Kim, JaeHwang; Kim, DaeHwan

    2018-03-01

    Fe is intentionally added in order to form the Fe intermetallic compounds (Fe-IMCs) during casting. Field emission scanning electron microscope with energy dispersive spectrometer (EDS) was conducted to understand microstructural changes and chemical composition analyses. The needlelike Fe-IMCs based on two dimensional observation with hundreds of micro size are modified to fragmented particles with the minimum size of 300 nm through clod rolling with 80% thickness reduction. The ratio of Fe:Si on the fragmented Fe-IMCs after 80% reduction is close to 1:1, representing the β-Al5FeSi. The yield and tensile strengths are increased with increasing reduction rate. On the other hand, the elongation is decreased with the 40% reduction, but slightly increased with the 60% reduction. The elongation is dramatically increased over two times for the specimen of 80% reduction compared with that of the as-cast. Fracture behavior is strongly affected by the morphology and size of Fe-IMCs. The fracture mode is changed from brittle to ductile with the microstructure modification of Fe-IMCs.

  1. Theoretical investigation on thermoelectric properties of (Ca,Sr,Ba)Fe2(As/Bi)2 compounds under temperature

    Science.gov (United States)

    Jayalakshmi, D. S.; Sundareswari, M.; Viswanathan, E.; Das, Abhijeet

    2018-04-01

    The electrical conductivity, resistivity and Seebeck coefficient, Pauli magnetic susceptibility and power factor are computed under temperature (100 K - 800 K) in steps of 100 K for the theoretically designed compounds namely (Ca,Sr,Ba)Fe2Bi2 and their parent compounds namely (Ca,Sr,Ba)Fe2As2 by using Boltzmann transport theory interfaced to the Wien2k program. The Bulk modulus, electron phonon coupling constant, thermoelectric figure of merit (ZT) and transition temperature are calculated for the optimized anti ferromagnetic phase of the proposed compounds. The results are discussed for the novel compounds in view of their superconductivity existence and compared with their parent unconventional superconducting compounds.

  2. Calculations of the magnetic properties of R{sub 2}M{sub 14}B intermetallic compounds (R=rare earth, M=Fe, Co)

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Masaaki, E-mail: masaaki.ito@neel.cnrs.fr [CNRS, Institut Néel, 25 rue des Martyrs, BP166, 38042 Grenoble (France); University Grenoble Alpes, Institut Néel, 38042 Grenoble (France); Advanced Material Engineering Division, Toyota Motor Corporation, Susono 410-1193 (Japan); Yano, Masao [Advanced Material Engineering Division, Toyota Motor Corporation, Susono 410-1193 (Japan); Dempsey, Nora M. [CNRS, Institut Néel, 25 rue des Martyrs, BP166, 38042 Grenoble (France); University Grenoble Alpes, Institut Néel, 38042 Grenoble (France); Givord, Dominique [CNRS, Institut Néel, 25 rue des Martyrs, BP166, 38042 Grenoble (France); University Grenoble Alpes, Institut Néel, 38042 Grenoble (France); Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro (Brazil)

    2016-02-15

    The hard magnetic properties of “R–M–B” (R=rare earth, M=mainly Fe) magnets derive from the specific intrinsic magnetic properties encountered in Fe-rich R{sub 2}M{sub 14}B compounds. Exchange interactions are dominated by the 3d elements, Fe and Co, and may be modeled at the macroscopic scale with good accuracy. Based on classical formulae that relate the anisotropy coefficients to the crystalline electric field parameters and exchange interactions, a simple numerical approach is used to derive the temperature dependence of anisotropy in various R{sub 2}Fe{sub 14}B compounds (R=Pr, Nd, Dy). Remarkably, a unique set of crystal field parameters give fair agreement with the experimentally measured properties of all compounds. This implies reciprocally that the properties of compounds that incorporate a mixture of different rare-earth elements may be predicted accurately. This is of special interest for material optimization that often involves the partial replacement of Nd with another R element and also the substitution of Co for Fe. - Highlights: • Anisotropy constants derived from CEF parameters of R{sub 2}M{sub 14}B compounds (M=Fe, Co). • Anisotropy constants of all R{sub 2}Fe{sub 14}B compounds using unique set of CEF parameters. • Moment non-collinearity in magnetization processes under B{sub app} along hard axis.

  3. NMR measurements in milled GdCo2 and GdFe2 intermetallic compounds

    International Nuclear Information System (INIS)

    Tribuzy, C.V.B.; Guimaraes, A.P.; Biondo, A.; Larica, C.; Alves, K.M.B.

    1998-12-01

    We have used the nuclear magnetic resonance technique to study the magnetic and structural properties of the Gd-Co and Gd-Fe metallic systems, starting with the C15 laves phase intermetallic compounds, and submitting them to a high energy milling process. This leads to the amorphization of the samples, as determined by the X-ray diffraction spectra. For the Gd-Co system the NMR study used the 59 Co nucleus; in the Gd-Fe system, 155,157 Gd and 57 Fe were used. Both systems showed segregation of the pure elements, after a few hours of milling. In the Gd-Co system, a single line, of increasing width, was observed in the 59 Co spectrum. In the Gd-Fe system, the 155 Gd and 157 Gd resonances show three lines, arising from electrical quadrupole interaction. With increasing milling time, the lines broaden, and extra lines appear attributed to a cubic phase of Gd; this interpretation is supported by the X-ray analysis of the samples. The 57 Fe NMR spectrum of this system also informs on the direction of magnetization of the samples in the early stages of milling. From 1 h to 7 h of milling, a spectrum of α-Fe was observed. The study of the NMR line intensity as a function of radio frequency (r.f.) power in Gd Co 2 suggests the existence of regions of the samples with different degrees of disorder. We have observed the persistence of NMR signals from the original intermetallic compounds in the samples with up to 10 h and 7 h of milling, respectively, for Gd Co 2 and Gd Fe 2 . (author)

  4. Pr-magnetism in the quasi-skutterudite compound PrFe2Al8.

    Science.gov (United States)

    Nair, Harikrishnan S; Ogunbunmi, Michael O; Kumar, C M N; Adroja, D T; Manuel, P; Fortes, D; Taylor, J; Strydom, A M

    2017-08-31

    The intermetallic compound PrFe 2 Al 8 that possesses a three-dimensional network structure of Al polyhedra centered at the transition metal element Fe and the rare earth Pr is investigated through neutron powder diffraction and inelastic neutron scattering in order to elucidate the magnetic ground state of Pr and Fe and the crystal field effects of Pr. Our neutron diffraction study confirms long-range magnetic order of Pr below [Formula: see text] K in this compound. Subsequent magnetic structure estimation reveals a magnetic propagation vector [Formula: see text] with a magnetic moment value of [Formula: see text]/Pr along the orthorhombic c-axis and evidence the lack of ordering in the Fe sublattice. The inelastic neutron scattering study reveals one crystalline electric field excitation near 19 meV at 5 K in PrFe 2 Al 8 . The energy-integrated intensity of the 19 meV excitation as a function of [Formula: see text] follows the square of the magnetic form factor of [Formula: see text] thereby confirming that the inelastic excitation belongs to the Pr sublattice. The second sum rule applied to the dynamic structure factor indicates only 1.6(2) [Formula: see text] evolving at the 19 meV peak compared to the 3.58 [Formula: see text] for free [Formula: see text], indicating that the crystal field ground state is magnetic and the missing moment is associated with the resolution limited quasi-elastic line. The magnetic order occurring in Pr in PrFe 2 Al 8 is counter-intuitive to the symmetry-allowed crystal field level scheme, hence, is suggestive of exchange-mediated mechanisms of ordering stemming from the magnetic ground state of the crystal field levels.

  5. Synthesis and crystal structure of the quaternary compound AgFe{sub 2}GaTe{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, Gerzon E., E-mail: gerzon@ula.ve [Laboratorio de Cristalografía, Departamento de Química, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101 (Venezuela, Bolivarian Republic of); Quintero, Eugenio; Tovar, Rafael; Grima-Gallardo, Pedro; Quintero, Miguel [Centro de Estudio de Semiconductores, Departamento de Física, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101 (Venezuela, Bolivarian Republic of)

    2014-11-15

    Highlights: • New quaternary compound. • Synthesis from solid state reaction. • Crystal structure. • Rietveld refinement. - Abstract: The crystal structure of the quaternary compound AgFe{sub 2}GaTe{sub 4}, belonging to the system I–II{sub 2}–III–VI{sub 4}, was characterized by Rietveld refinement using X-ray powder diffraction data. The powder pattern was composed by 84.5% of the principal phase AgFe{sub 2}GaTe{sub 4} and 15.5% of the secondary phase FeTe. This material crystallizes with stannite structure in the tetragonal space group I-42m (N° 121), Z = 2, unit cell parameters a = 6.3409(2) Å, c = 12.0233(4) Å, V = 483.42(3) Å{sup 3}, and is isostructural with CuFe{sub 2}InSe{sub 4}.

  6. Novel Fe-Pd/SiO2 catalytic materials for degradation of chlorinated organic compounds in water

    Science.gov (United States)

    Novel reactive materials for catalytic degradation of chlorinated organic compounds in water at ambient conditions have been prepared on the basis of silica-supported Pd-Fe nanoparticles. Nanoscale Fe-Pd particles were synthesized inside porous silica supports using (NH4

  7. Fabrication and thermal characterization of amorphous and nanocrystalline Al{sub 9}FeNi/Al{sub 3}Ti compound

    Energy Technology Data Exchange (ETDEWEB)

    Tavoosi, Majid, E-mail: ma.tavoosi@gmail.com

    2017-01-15

    In this study, the fabrication and structural characterization of amorphous/nanocrystalline Al{sub 9}FeNi/Al{sub 3}Ti phase has been performed. In this regards, milling and annealing processes were applied on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} (at. %) powder mixture for different periods of time. The prepared samples were characterized using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM) and differential scanning calorimetery (DSC). According to the results, supersaturated solid solution, nanocrystalline Al{sub 9}FeNi/Al{sub 3}Ti (with average crystallite size of about 7 nm) and amorphous phases indicated three different microstructures which can be formed in Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} system during milling process. The formed supersaturated solid solution and amorphous phases were unstable and transformed to Al{sub 9}FeNi/Al{sub 3}Ti intermetallic compound during annealing process. It is shown that, Al{sub 9}FeNi phase in Al{sub 9}FeNi/Al{sub 3}Ti intermetallic compound can decompose into Al{sub 3}Ni, Al{sub 13}Fe{sub 4} and liquid phases during a reversible peritectic reaction at 809 °C. - Highlights: • We study the effect of milling process on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} alloy. • We study the effect of annealing on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} supersaturated solid solution phase. • We study the effect of annealing on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} amorphous phase. • We study the thermal behaviour of Al{sub 9}FeNi/Al{sub 3}Ti compound.

  8. Structure and Hyperfine Interactions in Aurivillius Bi9Ti3Fe5O27 Conventionally Sintered Compound

    International Nuclear Information System (INIS)

    Mazurek, M.; Lisinska-Czekaj, A.; Surowiec, Z.; Jartych, E.; Czekaj, D.

    2011-01-01

    The structure and hyperfine interactions in the Bi 9 Ti 3 Fe 5 O 27 Aurivillius compound were studied using X-ray diffraction and Moessbauer spectroscopy. Samples were prepared by the conventional solid-state sintering method at various temperatures. An X-ray diffraction analysis proved that the sintered compounds formed single phases at temperature above 993 K. Moessbauer measurements have been carried out at room and liquid nitrogen temperatures. Room-temperature Moessbauer spectrum of the Bi 9 Ti 3 Fe 5 O 27 compound confirmed its paramagnetic properties. However, low temperature measurements revealed the additional paramagnetic phase besides the antiferromagnetic one. (authors)

  9. Browse Title Index

    African Journals Online (AJOL)

    Items 1 - 50 of 101 ... Issue, Title. Vol 3, No 4 (2014), Chlamydia trachomatis IgG antibodies seroprevalence among students in two tertiary institutions in Anambra state, Nigeria: a comparative study, Abstract PDF. CB Duru, FE Emele, ED Adinma, CO Ifeadike, KA Uwakwe, AO Oluboyo, BO Oluboyo, C Abejegah. Vol 2, No 1 ...

  10. Magnetic and magnetocaloric properties of HoCr0.75Fe0.25O3 compound

    Science.gov (United States)

    Kotnana, Ganesh; Babu, P. D.; Jammalamadaka, S. Narayana

    2018-05-01

    We report on the magnetic and magnetocaloric properties of HoCr0.75Fe0.25O3 compound around the Néel temperature (TN), which is due to Cr3+ ordering. Susceptibility (χ) vs. temperature (T) graph of HoCr0.75Fe0.25O3 compound infer two transitions due to the ordering of Cr3+ moments (TN ˜ 155 K) and Ho3+ moments (TNHo ˜ 8 K). Magnetic entropy (-ΔSM) value of 1.14 J kg-1 K-1 around 157.5 K with a magnetic field (H) of 90 kOe is attributed to antiferromagnetic (AFM) ordering of Cr3+ moments. A maximum value of adiabatic temperature (ΔTad) ˜ 0.41 K around TN is obtained and is found to increases with applied magnetic field. Negative slope for H/M vs. M2 graph is evident for HoCr0.75Fe0.25O3 compound below TN, which indicates the first order phase transition. Quantified values of -ΔSM and ΔTad open the way to explore rare earth orthochromites for the MCE properties and refrigeration applications.

  11. Investigation of structural imitation and lattice vibrations of Pr{sub 2}Fe{sub 17-} {sub x} Mn {sub x} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Shen Jiang [Institute of Applied Physics, University of Science and Technology Beijing, 30 Xueyuou Road, HaiDian District, Beijing 100083 (China)]. E-mail: shenj@sas.ustb.edu.cn; Qian Ping [Institute of Applied Physics, University of Science and Technology Beijing, 30 Xueyuou Road, HaiDian District, Beijing 100083 (China); Chen Nanxian [Institute of Applied Physics, University of Science and Technology Beijing, 30 Xueyuou Road, HaiDian District, Beijing 100083 (China); Department of Physics, Tsinghua University, Beijing 100084 (China)

    2005-03-15

    We have investigated the structural properties of Pr{sub 2}Fe{sub 17-} {sub x} Mn {sub x} compounds by using quasi-ab initio pair potentials {phi} {sub Fe-Fe}(r), {phi} {sub Pr-Fe}(r), {phi} {sub Pr-Pr}(r), {phi} {sub Pr-Mn}(r), {phi} {sub Fe-Mn}(r) and {phi} {sub Mn-Mn}(r). In Pr{sub 2}Fe{sub 17-} {sub x} Mn {sub x} , the ternary elements Mn substitute for Fe atoms without changing the crystal structure. The calculated cohesive energy curves show that for all values of x, Mn preferentially substitutes for Fe in the 6c site and randomly substitutes for Fe in the 18f and 18h site. The calculated lattice constants coincide quite well with experimental values. Furthermore, the phonon density, specific heat and vibrational entropy of these compounds are also calculated. It is interesting that simple pair potentials can describe these extremely anisotropic materials.

  12. Magnetocaloric effects in MnFeP1-x As x -based compounds

    International Nuclear Information System (INIS)

    Brueck, E.; Ilyn, M.; Tishin, A.M.; Tegus, O.

    2005-01-01

    Here we present the results of an investigation of some magnetic and thermal properties of the compounds MnFeP 0.45 As 0.55 , MnFeP 0.47 As 0.53 , and Mn 1.1 Fe 0.9 P 0.47 As 0.53 which can be regarded as possible magnetic refrigerants for room temperature applications. Magnetization measurements are performed in the temperature range 250-330 K, in magnetic fields up to 5 T. The coexistence of the magnetic and structural first-order phase transitions is revealed in all three samples, suggesting its key role in the large values observed for the magnetocaloric effect. The adiabatic temperature change measured directly was up to 4.0, 3.4, and 4.2 K for a magnetic field change of 1.45 T

  13. First-principles calculations of two cubic fluoropervskite compounds: RbFeF3 and RbNiF3

    Science.gov (United States)

    Mubarak, A. A.; Al-Omari, Saleh

    2015-05-01

    We present first-principles calculations of the structural, elastic, electronic, magnetic and optical properties for RbFeF3 and RbNiF3. The full-potential linear augmented plan wave (FP-LAPW) method within the density functional theory was utilized to perform the present calculations. We employed the generalized gradient approximation as exchange-correlation potential. It was found that the calculated analytical lattice parameters agree with previous studies. The analysis of elastic constants showed that the present compounds are elastically stable and anisotropic. Moreover, both compounds are classified as a ductile compound. The calculations of the band structure and density functional theory revealed that the RbFeF3 compound has a half-metallic behavior while the RbNiF3 compound has a semiconductor behavior with indirect (M-Γ) band gap. The ferromagnetic behavior was studied for both compounds. The optical properties were calculated for the radiation of up to 40 eV. A beneficial optics technology is predicted as revealed from the optical spectra.

  14. EXAFS study of Mn1.28Fe0.67P0.46Si0.54 compound with first-order phase transition

    International Nuclear Information System (INIS)

    L, Yingjie; Huliyageqi, B; Haschaolu, W; Song, Zhiqiang; Tegus, O; Nakai, Ikuo

    2014-01-01

    Highlights: • We have investigated the Fe and Mn K edge XAFS spectra of the Mn 1.28 Fe 0.67 P 0.46 Si 0.54 compound at 25 K and 295 K. • The site occupation of the Fe and Mn atoms and local structure of Mn 1.28 Fe 0.67 P 0.46 Si 0.54 are determined. • The atomic distances between Fe–Fe in c-plane for the ferromagnetic state are larger than those in the paramagnetic state. - Abstract: The Fe 2 P-type MnFe(P,Si) compounds are investigated by means of magnetic measurements and X-ray absorption fine structure spectroscopy. Magnetic measurements show that the Mn 1.28 Fe 0.67 P 0.46 Si 0.54 compound undergoes a first-order phase transition at the Curie temperature of 254 K. The Fe K-edge and Mn K-edge X-ray absorption fine structure spectra show that Mn atom mainly located at the 3g sites, while the 3f sites are occupied by Fe atoms and Mn atom randomly. The distances between the Fe atom and its nearest neighbor atoms in a triangle Fe–Mn–Fe change from 2.80 Å at 25 K to 2.74 Å at 300 K. On the other hand, the distances between Fe atom and its second neighbor atoms change from 4.06 Å at 25 K to 4.02 Å at 300 K

  15. Fe-moment instability in Ti{sub 1-x}Sc{sub x}Fe{sub 2} Laves-phase compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ouladdiaf, B. [Institut Laue-Langevin, BP 156, 38042 GRENOBLE Cedex 09 (France); Deportes, J. [Lab. Louis Neel, CNRS, BP 166, 38042 GRENOBLE Cedex 09 (France); Saoudi, M. [Centre Universitaire de Guelma, GUELMA 24 000 (Algeria)

    2002-07-01

    The magnetic properties of the pseudo-binary Laves-phase compounds Ti{sub 1-x}Sc{sub x}Fe{sub 2} were investigated by means of magnetisation and high-resolution powder neutron diffraction techniques. For x<0.2 a transition from an antiferromagnetic state to a canted one with a ferromagnetic component in the basal plane is observed, while for 0.2Fe atoms at the 2a site. (orig.)

  16. Crystal and magnetic structure of TbFe{sub 0.25}Ge{sub 2} compound

    Energy Technology Data Exchange (ETDEWEB)

    Gil, A., E-mail: a.gil@ajd.czest.pl [Faculty of Mathematics and Natural Sciences, Jan Długosz University in Częstochowa, Armii Krajowej 13/15, 42-200 Częstochowa (Poland); Hoser, A. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14-109 Berlin (Germany); Penc, B.; Szytuła, A. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Kraków (Poland)

    2013-10-15

    The crystal and magnetic structure of polycrystalline TbFe{sub 0.25}Ge{sub 2} sample have been determined. X-ray and neutron diffraction studies indicate that this compound has the orthorhombic CeNiSi{sub 2}-type crystal structure (space group Cmcm). The magnetic ordering, based on the neutron diffraction data in low temperature, is described by two components: a collinear antiferromagnetic G-type and a cosine-wave modulated one. In the collinear G-type structure the Tb magnetic moment is equal to 3.81(5) µ{sub B} and it is parallel to the c-axis. The modulated structure is described by the propagation vector k=(0.460(8), 0, 0.305(1)), the Tb magnetic moment equals 7.75(8) µ{sub B,} lies in b–c and forms an angle 23(2)° with the c-axis. The collinear component decreases to zero at 22.6 K while the modulated one at 190.8 K. - Highlights: • We determine crystal and magnetic structure of TbFe{sub 0.25}Ge{sub 2} compound. • We compare the results with other TbT{sub x}Ge{sub 2} compounds. • We observe the complex magnetic structure in TbFe{sub 0.25}Ge{sub 2} with two components: collinear and cosine-wave modulated. • T (3d) element have got significant influence on the interactions in Tb sublattice.

  17. Optical contrast spectra studies for determining thickness of stage-1 graphene-FeCl{sub 3} intercalation compounds

    Energy Technology Data Exchange (ETDEWEB)

    Han, Wen-Peng, E-mail: han-wenpeng@163.com, E-mail: yunze.long@163.com; Yan, Xu; Zhao, Hui [College of Physics, Qingdao University, Qingdao 266071 (China); Li, Qiao-Qiao; Lu, Yan [State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Long, Yun-Ze, E-mail: han-wenpeng@163.com, E-mail: yunze.long@163.com [College of Physics, Qingdao University, Qingdao 266071 (China); Collaborative Innovation Center for Low-Dimensional Nanomaterials and Optoelectronic Devices, Qingdao University, Qingdao 266071 (China)

    2016-07-15

    Because of novel features in their structural, electronic, magnetic and optical properties, especially potential applications in nanoelectronics, the few-layer graphene intercalation compounds (FLGICs) have been intensively studied recently. In this work, the dielectric constant of the doped graphene of stage-1 FeCl{sub 3}-GIC is obtained by fitting the optical contrast spectra. And fully intercalated stage-1 FeCl{sub 3}-FLGICs were prepared by micromechanical cleavage method from graphite intercalation compounds (GICs) for the first time. Finally, we demonstrated that the thickness of stage-1 FeCl{sub 3}-GICs by micromechanical cleavage can be determined by optical contrast spectra. This method also can be used to other FLGICs, such as SbCl{sub 5}-FLGICs and AuCl{sub 5}-FLGICs, etc.

  18. Synthesis by two methods and crystal structure determination of a new pyrochlore-related compound Sm{sub 2}FeTaO{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Martinez, Leticia M., E-mail: lettorresg@yahoo.com [Departamento de Ecomateriales y Energia, Facultad de Ingenieria Civil, Universidad Autonoma de Nuevo Leon, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Ruiz-Gomez, Miguel A. [Departamento de Ecomateriales y Energia, Facultad de Ingenieria Civil, Universidad Autonoma de Nuevo Leon, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, Av. Manuel Nava 6, San Luis Potosi, S.L.P. 78290 (Mexico); Figueroa-Torres, M.Z.; Juarez-Ramirez, Isaias [Departamento de Ecomateriales y Energia, Facultad de Ingenieria Civil, Universidad Autonoma de Nuevo Leon, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Moctezuma, Edgar [Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, Av. Manuel Nava 6, San Luis Potosi, S.L.P. 78290 (Mexico); and others

    2012-04-16

    Graphical abstract: The monoclinic (space group C2/c) structure of a new compound, Sm{sub 2}FeTaO{sub 7} shows an alternating Sm-O and Fe/Ta-O layers. In the Fe/Ta-O layer, Fe/Ta1 and Fe/Ta3 cations are coordinated by six oxygen atoms, forming irregular octahedral interconnected into a hexagonal tungsten bronze (HTB) type network. The HTB layer is a fundamental framework in the pyrohlore-related structure. Highlights: Black-Right-Pointing-Pointer Pyrochlore-related compound Sm{sub 2}FeTaO{sub 7} prepared by solid state reaction and sol-gel. Black-Right-Pointing-Pointer Sm{sub 2}FeTaO{sub 7} crystallizes with a monoclinic crystal structure and space group C2/c. Black-Right-Pointing-Pointer The compound is synthesized by sol-gel at lower temperature and time than solid state. Black-Right-Pointing-Pointer Surface area of sol-gel Sm{sub 2}FeTaO{sub 7} is 10 times higher than that prepared by solid state. - Abstract: This paper reports on the synthesis of a new pyrochlore-related compound Sm{sub 2}FeTaO{sub 7} by both solid state reaction and sol-gel synthesis routes. Structural features were determined by X-ray powder diffraction and Rietveld refinement and were corroborated using Transmission Electron Microscopy (TEM). The results revealed that Sm{sub 2}FeTaO{sub 7} crystallized in the monoclinic system with space group C2/c and the following cell parameters: a = 13.1307(5) Angstrom-Sign , b = 7.5854(3) Angstrom-Sign , c = 11.6425(4) Angstrom-Sign and {beta} = 100.971(2) Degree-Sign . The monoclinic structure of Sm{sub 2}FeTaO{sub 7} showed an arrangement of alternating Sm-O and Fe/Ta-O layers and two types of irregular octahedra of Fe/Ta-O, which are interconnected into a hexagonal tungsten bronze (HTB)-type network. On the other hand, Sm{sub 2}FeTaO{sub 7} prepared by sol-gel was obtained with lower particle sizes than the solid state produced compound. The difference in particle size causes a difference of one order of magnitude in the specific surface area. In

  19. Longitudinal recording on FePt and FePtX (X = B, Ni) intermetallic compounds

    Science.gov (United States)

    Li, Ning

    1999-11-01

    Near field recording on high coercivity FePt intermetallic compound media using a high Bsat write element was investigated. Untextured FePt media were prepared by magnetron sputtering on ZrO2 disks at a substrate temperature of 450°C, with post annealing at 450°C for 8 hrs. Both multilayer and cosputtered precursors produced the ordered tetragonal L10 phase with high coercivity between 5kOe and 12kOe. To improve readback noise decrease magnetic domain size, FePtB media were subsequently prepared by cosputtering. Over-write, roll-off, signal to noise ratio and non-linear transition shift (NLTS) ere measured by both metal in gap (MIG) and merged MR heads. FePtB media showed similar NLTS to commercial CoCrPtTa longitudinal media, but 5dB lower signal to noise ratio. By operating recording transducers in near contact, reasonable values of (>30dB) could be obtained. VSM Rotational Transverse Magnetization has been used for measuring the anisotropy field of magnetic thin films. Magnetization reversal during rotation of a 2D isotropic an applied field is discussed. The relationship between the transverse magnetization My and the applied field H was numerically solved. An excellent approximation for the transverse magnetization is found to be: My/Ms=A(1- H/Hk) 2.5, where A = 1.1434, and Hk is the anisotropy field. For curve fitting to experimental data, both A and Hk were used as fitting parameters. Comparison between a constructed torque hysteresis method and this VSM RTM method have been made theoretically and experimentally. Both results showed that VSM RTM will give better extrapolation of the anisotropy field. The torque measurement will slightly overestimate the anisotropy field. The anisotropy fields of FePt and FePtX (X = B, Ni) films were characterized using this VSM RTM technique with comparison to a CoCrTaPt disk. Anisotropy energy was derived. Hc/Hk was used as an indicator for coherent rotation of a single domain. Interactions between magnetic domains were

  20. Zero thermal expansion in NaZn13-type La(Fe,Si)13 compounds.

    Science.gov (United States)

    Wang, Wei; Huang, Rongjin; Li, Wen; Tan, Jie; Zhao, Yuqiang; Li, Shaopeng; Huang, Chuanjun; Li, Laifeng

    2015-01-28

    A zero thermal expansion material in a pure form of NaZn13-type La(Fe,Si)13 was fabricated. Through optimizing the chemical composition, an isotropic zero thermal expansion material is achieved. The obtained materials exhibit a low expansion of |α| linear thermal expansion) over a broad temperature range (15-150 K). The present study indicates that the thermal expansion behavior of the NaZn13-type La(Fe,Si)13 compounds depends mainly on the content of Si element. This new material is desirable in many fields of industry as a reliable and low-cost zero thermal expansion material.

  1. Effect of interstitial nitrogen on magnetism and entropy change of LaFe11.7Si1.3 compound

    International Nuclear Information System (INIS)

    Balli, M.; Rosca, M.; Fruchart, D.; Gignoux, D.

    2009-01-01

    Crystal structure, magnetism and magnetocaloric properties of LaFe 11.7 Si 1.3 N y (y=0, 1.3) compounds have been studied by X-ray diffraction and magnetic measurements. The LaFe 11.7 Si 1.3 N y compounds present a cubic NaZn 13 -type structure. Insertion of 1.3 nitrogen atoms per LaFe 11.7 Si 1.3 formula increases the lattice parameter and Curie temperature from 11.467 to 11.733 A and from 190 to ∼230 K, respectively. Besides, the absorption of nitrogen drives drastically the magnetic transition from first to second order and accordingly strongly decreases the magnetocaloric effect compared to the parent alloy. Under an external field change of 5 T, the value of isothermal entropy change -ΔS is about 28 and 3.5 J/kg K for LaFe 11.7 Si 1.3 and LaFe 11.7 Si 1.3 N 1.3 , respectively, close to their Curie temperature. However, the relative cooling power RCP(S) of the nitride is about half that of the parent alloy

  2. Assessment of off-stoichiometric Zr33-xFe52+xSi15 C14 Laves phase compounds as permanent magnet materials

    Science.gov (United States)

    Gabay, A. M.; Hadjipanayis, G. C.

    2018-05-01

    Recently, Fe-based rare-earth-free compounds with non-cubic crystal structures were proposed as a base for permanent magnets which would not rely on critical elements. In this work, two series of alloys, Zr27Fe73-wSiw (0 ≤ w ≤ 15) and Zr33-xFe52+xSi15 (0 ≤ x ≤ 11), were prepared and characterized after annealing at 1538 K in order to determine the fundamental magnetic properties of the C36 and C14 hexagonal Laves phase compounds. A mixture of the cubic C15 and Zr6Fe23 structures was observed instead of the expected C36 structure. The hexagonal C14 was found in all Zr33-xFe52+xSi15 alloys with its lattice parameters linearly decreasing as the Fe(Si) atoms occupy the Zr sites in the Laves phase crystal structure. The solubility limit of Fe in the C14 structure at 1538 K corresponds to x = 9.5. The Curie temperature of the C14 compounds increases with deviation from the Laves phase stoichiometry from 290 K to 530 K. The room-temperature spontaneous magnetization also increases reaching, after correcting for the non-magnetic impurities, a value of 6.7 kG. The magnetocrystalline anisotropy of the off-stoichiometric C14 Laves phase was found to be uniaxial with the easy magnetization direction parallel to the hexagonal axis. Unfortunately, the anisotropy field, which does not exceed 10 kOe, is not sufficiently high to make the compounds interesting as permanent magnet materials.

  3. Fe-vacancy and superconductivity in FeSe-based superconductors

    Science.gov (United States)

    Wang, C. H.; Chen, T. K.; Chang, C. C.; Lee, Y. C.; Wang, M. J.; Huang, K. C.; Wu, P. M.; Wu, M. K.

    2018-06-01

    This review summarizes recent advancements in FeSe and related systems. The FeSe and related superconductors are currently receiving considerable attention for the high Tcs observed and for many similar features to the high Tc cuprate superconductors. These similarities suggest that understanding the FeSe based compounds could potentially help our understanding of the cuprates. We shall first review the common features observed in the FeSe-based system. It was found that with a careful control of material synthesizing processes, numerous rich phases have been observed in the FeSe-based system. Detailed studies show that the Fe-vacancy ordered phases found in the FeSe based compounds, which are non-superconducting Mott insulators, are the parent compounds of the superconductors. Superconductivity emerges from the parent phases by disordering the Fe vacancy order, often by a simple annealing treatment. Recent high temperature X-ray diffraction experiments show that the degree of structural distortion associated with the disorder of Fe-vacancy is closely related to volume fraction of the superconductivity observed. These results suggest the strong lattice to spin coupling are important for the occurrence of superconductivity in FeSe based superconductors.

  4. Pentacarbonyl-1κ2C,2κ3C-[(diphenylphosphoryldiphenylphosphane-1κP]-μ-ethane-1,2-dithiolato-1:2κ4S,S′:S,S′-diiron(I(Fe—Fe

    Directory of Open Access Journals (Sweden)

    Xu-Feng Liu

    2011-11-01

    Full Text Available The dinuclear title compound, [Fe2(C2H4S2(C24H20OP2(CO5] or (μ-SCH2CH2S-μFe2(CO5[Ph2PP(OPh2], contains a butterfly-shaped Fe2S2 core in which the Fe...Fe separation is 2.5275 (6 Å. One of the Fe atoms is also coordinated to three carbonyl ligands and the other to two carbonyl ligands and one phosphane ligand [Ph2PP(OPh2]. Both Fe-atom geometries could be described as grossly distorted octahedral and the Ph2PP(OPh2 ligand lies trans to the Fe...Fe link.

  5. A (Nd, Zr(Fe, Co11.5Ti0.5Nx compound as a permanent magnet material

    Directory of Open Access Journals (Sweden)

    S. Suzuki

    2014-11-01

    Full Text Available We studied NdFe11TiNx compounds as permanent magnet materials. The (Nd0.7,Zr0.3(Fe0.75Co0.2511.5Ti0.5N0.52 powder that contained a limited amount of the α-(Fe, Co phase shows fairly good magnetic properties, such as a saturation polarization (Js of 1.68 T and an anisotropic field (Ha of 2.88 (Law of approach to saturation – 4.0 MA/m (Intersection of magnetization curves. Both properties are comparable to those of the Nd2Fe14B phase.

  6. Behavior of methyl orange and orange 10 (orange G) in the presence of hydrotalcite type compounds of Mg/Al and Mg/Fe

    International Nuclear Information System (INIS)

    Cruz N, G.

    2015-01-01

    This work is focused on studying the sorption capacity of methyl orange dye (Nm) and orange 10 (N-10) in the presence of hydrotalcite type compounds of Mg/Al and Mg/Fe uncalcined and calcined previously at 500 degrees Celsius. Sorption isotherms were determined and the study of the kinetics of sorption was performed. The materials were characterized before and after sorption processes of these dyes by X-ray diffraction, scanning electron microscopy, the specific surface area determination by the Brunauer-Emmett-Teller method, thermogravimetry coupled to mass and infrared spectrometry. The hydrotalcite type compounds reported in this paper were prepared in the laboratory and their acronyms are: HTMgAlG1, HTMgAlMO, HTMgFeG1 and HTMgFeG2. Note that in this work the best conditions for preparing compounds of Mg/Fe were found. From patterns of X-ray diffraction was identified the typical crystal structure of the hydrotalcite type compounds. By scanning electron microscopy the morphology could be determined in the form of flakes characteristics of these compounds. Likewise with elemental analysis of energy dispersive X-ray spectroscopy the presence of Mg, Al, Fe and C, elements of interest for this study was determined. The compounds presented a specific surface area relatively high from 80 to 120 m 2 /g. Thermogravimetry results presented spectra of mass loss very characteristic associated to water losses, dehydroxylation and decarboxylation. The characteristic bands of water and carbonate were assigned by infrared spectroscopy and the bands corresponding to the dyes sulfonates were identified only for the calcined materials. The sorption capacities found of these compounds were as follows: for Nm in the compound HTMgAlG1 uncalcined was 17.82 mg/g for an initial concentration of 200 mg/L and for calcined (HTMgAlMOcal) of 99.8 mg/g with and initial concentration of 1000 mg/L. Moreover, the sorption capacity of the dye N-10 in this same material was 17.92 mg/g and 99.4 mg

  7. Magneto-caloric effect in the pseudo-binary intermetallic YPrFe{sub 17} compound

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, Pablo [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Gorria, Pedro, E-mail: pgorria@uniovi.es [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Sanchez Llamazares, Jose L. [Division de Materiales Avanzados, Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la presa San Jose 2055, CP 78216, San Luis Potosi (Mexico); Perez, Maria J. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Franco, Victorino [Departamento de Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, 41080 Sevilla (Spain); Reiffers, Marian; Kovac, Jozef [Institute of Experimental Physics, Watsonova 47, SK-04001 Kosice (Slovakia); Puente-Orench, Ines [Institute Laue Langevin, 6 rue Jules Horowitz, 38042 Grenoble (France); Blanco, Jesus A. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer YPrFe{sub 17} exhibits a broad {Delta}S{sub M}(T) associated with the ferro-to-paramagnetic phase transition (T{sub C} Almost-Equal-To 290 K). Black-Right-Pointing-Pointer We obtain |{Delta}S{sub M}| Almost-Equal-To 2.3 J kg{sup -1} K{sup -1} and RCP Almost-Equal-To 100 J kg{sup -1}for a magnetic field change of 1.5 T. Black-Right-Pointing-Pointer A single master curve for {Delta}S{sub M} is found when compared with other isostructural R{sub 2}Fe{sub 17} binary alloys. - Abstract: We have synthesized the intermetallic YPrFe{sub 17} compound by arc-melting. X-ray and neutron powder diffraction show that the crystal structure is rhombohedral with R3{sup Macron }m space group (Th{sub 2}Zn{sub 17}-type). The investigated compound exhibits a broad isothermal magnetic entropy change {Delta}S{sub M}(T) associated with the ferro-to-paramagnetic phase transition (T{sub C} Almost-Equal-To 290 K). The |{Delta}S{sub M}| ( Almost-Equal-To 2.3 J kg{sup -1} K{sup -1}) and the relative cooling power ( Almost-Equal-To 100 J kg{sup -1}) have been calculated for applied magnetic field changes up to 1.5 T. A single master curve for {Delta}S{sub M} under different values of the magnetic field change can be obtained by a rescaling of the temperature axis. The results are compared and discussed in terms of the magneto-caloric effect in the isostructural R{sub 2}Fe{sub 17} (R = Y, Pr and Nd) binary intermetallic alloys.

  8. Fe-Cluster Compounds of Chalcogenides: Candidates for Rare-Earth-Free Permanent Magnet and Magnetic Nodal-Line Topological Material.

    Science.gov (United States)

    Zhao, Xin; Wang, Cai-Zhuang; Kim, Minsung; Ho, Kai-Ming

    2017-12-04

    Fe-cluster-based crystal structures are predicted for chalcogenides Fe 3 X 4 (X = S, Se, Te) using an adaptive genetic algorithm. Topologically different from the well-studied layered structures of iron chalcogenides, the newly predicted structures consist of Fe clusters that are either separated by the chalcogen atoms or connected via sharing of the vertex Fe atoms. Using first-principles calculations, we demonstrate that these structures have competitive or even lower formation energies than the experimentally synthesized Fe 3 X 4 compounds and exhibit interesting magnetic and electronic properties. In particular, we show that Fe 3 Te 4 can be a good candidate as a rare-earth-free permanent magnet and Fe 3 S 4 can be a magnetic nodal-line topological material.

  9. Synthesis of homogeneous Ca0.5Sr0.5FeO2.5+δ compound using a mirror furnace method

    International Nuclear Information System (INIS)

    Mahboub, M.S.; Zeroual, S.; Boudjada, A.

    2012-01-01

    Graphical abstract: X-ray diffraction pattern indexing of Ca 0.5 Sr 0.5 FeO 2.5+δ powder sample obtained by mirror furnace method after thermal treatment. Highlights: ► A homogenous compound Ca 0.5 Sr 0.5 FeO 2.5+δ has been synthesized for the first time by a mirror furnace method. ► Ca 0.5 Sr 0.5 FeO 2.5+δ powder sample is perfectly homogenous, confirmed by X-ray diffraction, Raman spectroscopy and EDS technique. ► The thermal treatment of Ca 0.5 Sr 0.5 FeO 2.5+δ powder sample can increase their average grain sizes. -- Abstract: A new synthesis method using melting zone technique via the double mirror furnace around 1600 °C is used to obtain homogenous brownmillerite compounds Ca 1−x Sr x FeO 2.5+δ in the range 0.3 ≤ x ≤ 0.7. These compounds play important role in understanding the mystery of the oxygen diffusion in the perovskite-related oxides. We have successfully solved the miscibility gap problem by synthesizing a good quality of homogenous powder samples of Ca 0.5 Sr 0.5 FeO 2.5+δ compound. Our result was confirmed by X-rays diffraction, Raman spectroscopy and energy dispersive spectroscopy analysis. Thermal treatment was also applied until 800 °C under vacuum to confirm again the homogeneity of powder samples, improve its quality and show that no decomposition or return to form Ca- and Sr-enriched microdomains takes place as a result of phase separation.

  10. Electronic response of rare-earth magnetic-refrigeration compounds GdX2 (X = Fe and Co)

    Science.gov (United States)

    Bhatt, Samir; Ahuja, Ushma; Kumar, Kishor; Heda, N. L.

    2018-05-01

    We present the Compton profiles (CPs) of rare-earth-transition metal compounds GdX2 (X = Fe and Co) using 740 GBq 137Cs Compton spectrometer. To compare the experimental momentum densities, we have also computed the CPs, electronic band structure, density of states (DOS) and Mulliken population (MP) using linear combination of atomic orbitals (LCAO) method. Local density and generalized gradient approximations within density functional theory (DFT) along with the hybridization of Hartree-Fock and DFT (B3LYP and PBE0) have been considered under the framework of LCAO scheme. It is seen that the LCAO-B3LYP based momentum densities give a better agreement with the experimental data for both the compounds. The energy bands and DOS for both the spin-up and spin-down states show metallic like character of the reported intermetallic compounds. The localization of 3d electrons of Co and Fe has also been discussed in terms of equally normalized CPs and MP data. Discussion on magnetization using LCAO method is also included.

  11. Magnetic properties and magnetocaloric effect of MnFeP0.5Ge0.5-xSix compounds

    International Nuclear Information System (INIS)

    Song, L.; Wang, G.F.; Ou, Z.Q.; Haschaolu, O.; Tegus, O.; Brueck, E.; Buschow, K.H.J.

    2009-01-01

    We have studied the magnetic properties and magnetic-entropy changes of the MnFeP 0.5 Ge 0.5-x Si x compounds with x = 0.1, 0.2, 0.3, 0.4 and 0.45. X-ray diffraction shows that the compounds crystallize in the Fe 2 P-type hexagonal structure. The lattice parameter a and the Curie temperature decreases with increasing x. The maximal magnetic-entropy changes for x = 0.4 and 0.45 derived from the magnetization data are about 6.0 J/kg K and 5.8 J/kg K, respectively, for a field change from 0 to 1.5 T

  12. Phase diagram of pressure-induced superconductor β-(BDA-TTP)2MX4 (M=Fe, Ga and X=Cl, Br) with localized magnetic moments

    Science.gov (United States)

    Choi, E. S.; Graf, D.; Tokumoto, T.; Brooks, J. S.; Yamada, Jun-Ichi

    2007-03-01

    We have investigated transport and magnetization properties of β-(BDA-TTP)2MX4 (M=Fe, Ga and X=Cl, Br) as a function of pressure, temperature and magnetic field. The title material undergoes metal-insulator transitions above 100 K at ambient pressure. The insulating phase is suppressed with pressure and superconductivity eventually appears above Pc= 4.5 kbar (X=Cl) and 13 kbar (X=Br). The general temperature-pressure (TP) phase diagram is similar each other, while higher pressure is required for X=Br compounds to suppress the insulating state and induce the superconductivity. Pressure dependent DC magnetization studies on β-(BDA-TTP)2FeCl4 compound revealed that the AFM ordering persist well above Pc. In spite of similarity of phase diagram between M=Fe and M=Ga compounds, magnetoresistance results show distinct behaviors, which indicates the magnetic interaction with the conduction electrons are still effective. The comparison between X=Cl and X=Br compounds suggests the anion-size effect rather than the existence of localized magnetic moments plays more important role in determining the ground state.

  13. Crystal growth, electronic structure, and properties of Ni-substituted FeGa{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Likhanov, Maxim S. [Department of Chemistry, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Verchenko, Valeriy Yu. [Department of Chemistry, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); National Institute of Chemical Physics and Biophysics, 12618 Tallinn (Estonia); Bykov, Mikhail A. [Department of Chemistry, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Tsirlin, Alexander A. [National Institute of Chemical Physics and Biophysics, 12618 Tallinn (Estonia); Experimental Physics VI, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, 86135 Augsburg (Germany); Gippius, Andrei A. [Faculty of Physics, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Shubnikov Institute of Crystallography, Russian Academy of Science, 119333, Moscow (Russian Federation); Berthebaud, David; Maignan, Antoine [Laboratoire CRISMAT, UMR 6508 CNRS/ENSICAEN, F-14050 CAEN Cedex 4 (France); Shevelkov, Andrei V., E-mail: shev@inorg.chem.msu.ru [Department of Chemistry, Lomonosov Moscow State University, Moscow 119991 (Russian Federation)

    2016-04-15

    Crystals of the Fe{sub 1−x}Ni{sub x}Ga{sub 3} limited solid solution (x<0.045) have been grown from gallium flux. We have explored the electronic structure as well as magnetic and thermoelectric properties of Fe{sub 0.975}Ni{sub 0.025}Ga{sub 3} in comparison with Fe{sub 0.95}Co{sub 0.05}Ga{sub 3}, following the rigid band approach and assuming that one Ni atom donates twice the number of electrons as one Co atom. However, important differences between the Co- and Ni-doped compounds are found below 620 K, which is the temperature of the metal-to-insulator transition for both compounds. We have found that Fe{sub 0.975}Ni{sub 0.025}Ga{sub 3} displays lower degree of spatial inhomogeneity on the local level and exhibits diamagnetic behavior with a broad shallow minimum in the magnetic susceptibility near 35 K, in sharp contrast with the Curie–Weiss paramagnetism of Fe{sub 0.95}Co{sub 0.05}Ga{sub 3}. Transport measurements have shown the maximum of the thermoelectric figure-of-merit ZT of 0.09 and 0.14 at 620 K for Fe{sub 0.975}Ni{sub 0.025}Ga{sub 3} and Fe{sub 0.95}Co{sub 0.05}Ga{sub 3}, respectively. - Graphical abstract: Crystals of Ni-substituted FeGa{sub 3} up to 8 mm long were grown from gallium flux (see Figure for the temperature profile and crystal shape) that allowed studying magnetic and thermoelectric properties of the title solid solution.

  14. Magnetic anisotropy of (Sm, Y)2Fe17Ny compounds

    International Nuclear Information System (INIS)

    Lu, Y.; Tegus, O.; Li, Q.A.; Tang, N.; Yu, M.J.; Zhao, R.W.; Kuang, J.P.; Yang, F.M.; Zhou, G.F.; Li, X.; Boer, F.R. de

    1992-01-01

    A study of the crystal structure and the magnetic properties, especially the magnetocrystalline anisotropy of (Sm 1-x Y x ) 2 Fe 17 N y compounds (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0, 2 2 Zn 17 - or Th 2 Ni 17 -type structure as the original compounds. The Curie temperatures decrease from 750 to 700 K as x increases from 0 to 1. The anisotropy field decreases linearly with increasing yttrium content. The spin reorientation has been investigated by means of high field magnetization measurements, AC-susceptibility measurements and thermomagnetic analysis, combined with X-ray diffraction. The anisotropy constants K 1 , K 2 and K 3 were derived by a phenomenological analysis, using magnetization curves measured in high fields, applied perpendicular to the alignment direction of the powder samples. A tentative spin phase diagram of the series is presented. (orig.)

  15. Deduction of the chemical state and the electronic structure of Nd{sub 2}Fe{sub 14}B compound from X-ray photoelectron spectroscopy core-level and valence-band spectra

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jing; Liang, Le [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Zhang, Lanting, E-mail: lantingzh@sjtu.edu.cn, E-mail: lmsun@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Hirano Institute for Materials Innovation, Shanghai Jiao Tong University, Shanghai 200240 (China); Sun, Limin, E-mail: lantingzh@sjtu.edu.cn, E-mail: lmsun@sjtu.edu.cn [Instrumental Analysis Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Hirano, Shinichi [Hirano Institute for Materials Innovation, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2014-10-28

    Characterization of chemical state and electronic structure of the technologically important Nd{sub 2}Fe{sub 14}B compound is attractive for understanding the physical nature of its excellent magnetic properties. X-ray photoelectron spectroscopy (XPS) study of such rare-earth compound is important and also challenging due to the easy oxidation of surface and small photoelectron cross-sections of rare-earth 4f electrons and B 2p electrons, etc. Here, we reported an investigation based on XPS spectra of Nd{sub 2}Fe{sub 14}B compound as a function of Ar ion sputtering time. The chemical state of Fe and that of B in Nd{sub 2}Fe{sub 14}B compound can be clearly determined to be 0 and −3, respectively. The Nd in Nd{sub 2}Fe{sub 14}B compound is found to have the chemical state of close to +3 instead of +3 as compared with the Nd in Nd{sub 2}O{sub 3}. In addition, by comparing the valence-band spectrum of Nd{sub 2}Fe{sub 14}B compound to that of the pure Fe, the contributions from Nd, Fe, and B to the valence-band structure of Nd{sub 2}Fe{sub 14}B compound is made more clear. The B 2p states and B 2s states are identified to be at ∼11.2 eV and ∼24.6 eV, respectively, which is reported for the first time. The contribution from Nd 4f states can be identified both in XPS core-level spectrum and XPS valence-band spectrum. Although Nd 4f states partially hybridize with Fe 3d states, Nd 4f states are mainly localized in Nd{sub 2}Fe{sub 14}B compound.

  16. Magnetic and hyperfine interactions in HoFe{sub 1−x}Cr{sub x}O{sub 3} (0≤x≤1) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Kotnana, Ganesh [Magnetic Materials and Device Physics Laboratory, Department of Physics, Indian Institute of Technology Hyderabad, Hyderabad 502285 (India); Reddy, V. Raghavendra [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452001 (India); Jammalamadaka, S. Narayana, E-mail: surya@iith.ac.in [Magnetic Materials and Device Physics Laboratory, Department of Physics, Indian Institute of Technology Hyderabad, Hyderabad 502285 (India)

    2017-05-01

    We report on the magnetic and Mössbauer properties of polycrystalline HoFe{sub 1-x}Cr{sub x}O{sub 3} (0≤x≤1) compounds. Magnetization data reveals the continuous tailoring of magnetic transition due to weakening of Ho{sup 3+}-Fe{sup 3+} and Fe{sup 3+}-Fe{sup 3+} interactions in the entire temperature range by replacing the Fe{sup 3+} ions with Cr{sup 3+} ions. The observed decrease in Néel temperature (T{sub N}) and increase in spin re-orientation transition temperature (T{sub SR}) with the replacement of Fe{sup 3+} with Cr{sup 3+} is ascribed to the weakening of Fe(Cr)-O-Fe(Cr) antiferromagnetic exchange interaction. In addition, we also attribute such a change in T{sub N} to the enhancement of ferromagnetic interaction of adjacent Cr{sup 3+} moments through t-e hybridization as a result of the structural distortion. The decrease in isomer shift (IS) suggests enhancement of the interaction between nuclear charge with the 3s electrons as a result of decrease in radial part of 3d wave function with Cr addition. In this paper we also discuss about the variation of quadrupole splitting (QS) and hyperfine fields (H{sub hf}) with Cr addition in HoFe{sub 1-x}Cr{sub x}O{sub 3} (0≤x≤1) compounds. - Highlights: • Magnetic and Mössbauer properties of HoFe{sub 1-x}Cr{sub x}O{sub 3} (0≤x≤1) compounds. • T{sub N} changes due to weakening of Ho{sup 3+}-Fe{sup 3+} and Fe{sup 3+}-Fe{sup 3+} interactions with Cr. • The decrease in isomer shift (IS) is due to decrease in radial part of 3d wavefunction. • Octahedral distortion leads to increase in quadrupole splitting.

  17. Crystal structure of (Na0.70(Na0.70,Mn0.30(Fe3+,Fe2+2Fe2+(VO43, a sodium-, iron- and manganese-based vanadate with the alluaudite-type structure

    Directory of Open Access Journals (Sweden)

    Elhassan Benhsina

    2016-02-01

    Full Text Available The title compound, sodium (sodium,manganese triiron(II,III tris[vanadate(V], (Na0.70(Na0.70,Mn0.30(Fe3+,Fe2+2Fe2+(VO43, was prepared by solid-state reactions. It crystallizes in an alluaudite-like structure, characterized by a partial cationic disorder. In the structure, four of the 12 sites in the asymmetric unit are located on special positions, three on a twofold rotation axis (Wyckoff position 4e and one on an inversion centre (4b. Two sites on the twofold rotation axis are entirely filled by Fe2+ and V5+, whereas the third site has a partial occupancy of 70% by Na+. The site on the inversion centre is occupied by Na+ and Mn2+ cations in a 0.7:0.3 ratio. The remaining Fe2+ and Fe3+ atoms are statistically distributed on a general position. The three-dimensional framework of this structure is made up of kinked chains of edge-sharing [FeO6] octahedra stacked parallel to [10-1]. These chains are held together by VO4 tetrahedral groups, forming polyhedral sheets perpendicular to [010]. Within this framework, two types of channels extending along [001] are present. One is occupied by (Na+/Mn2+ while the second is partially occupied by Na+. The mixed site containing (Na+/Mn2+ has an octahedral coordination sphere, while the Na+ cations in the second channel are coordinated by eight O atoms.

  18. The effects of different heat treatment annealing on structural properties of LaFe11.5Si1.5 compound

    Science.gov (United States)

    Norizan, Yang Nurhidayah Asnida; Din, Muhammad Faiz Md; Zamri, Wan Fathul Hakim W.; Hashim, Fakroul Ridzuan; Jusoh, Mohd Taufik; Rahman, Mohd Rashid Abdul

    2018-02-01

    The cubic NaZn13-type LaFe13-xSix based compounds have been studied systematically and has become one of the most interesting systems for exploring large MCE. Its magnetic properties are strongly doping dependent and provides many of advantage compare to other as magnetic materials for magnetic refrigerator application. In other to produce high quality of cubic NaZn13-type structure, the structural properties of LaFe11.5Si1.5 compounds annealed at different temperature have been investigated. The LaFe11.5Si1.5 compounds was prepared by arc melting and annealed at two different heat treatment which are 1323 K for 14 days and 1523 K for 4 hour. The powder X-ray diffraction (XRD) shows that a short time and high temperature annealing process has benefits for the formation of the NaZn13-type phase compared to a long time and low temperature annealing process. This is shown by the weight fraction of cubic NaZn13- type structure increases from 80% for low temperature annealing to 83% for high temperature annealing. At the same time, high temperature annealing increase the main structure and decrease the impurity (α-Fe and LaFeSi). Furthermore, it can be clearly seen in the Rietveld refinement results that the lattice parameter is increase at the high temperature annealing because of more cubic NaZn13 is formed at higher temperature.

  19. Magnetocaloric effect in the La0.8Ce0.2Fe11.4-xCoxSi1.6 compounds

    International Nuclear Information System (INIS)

    Wang, G.F.; Song, L.; Li, F.A.; Ou, Z.Q.; Tegus, O.; Brueck, E.; Buschow, K.H.J.

    2009-01-01

    The effects of substitution of Co for Fe on the magnetic and magnetocaloric properties of La 0.8 Ce 0.2 Fe 11.4-x Co x Si 1.6 (0, 0.2, 0.4, 0.6, 0.8 and 1.0) compounds have been investigated. X-ray diffraction shows that all compounds crystallize in the NaZn 13 -type structure. Magnetic measurements show that the Curie temperature (T C ) can be tuned between 184 and 294 K by changing the Co content from 0 to 1. A field-induced methamagnetic transition occurs in samples with x=0, 0.2 and 0.4. The magnetic entropy changes of the compounds have been determined from the isothermal magnetization measurements by using the Maxwell relation.

  20. Structure and oxidation states of giant unit cell compound Dy{sub 117+x}Fe{sub 57-y}Sn{sub 112-z}

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Alexander T.; Barron, Keaton G.; Salazar, Bryan G.; Kirby, Parker; McCandless, Gregory T. [Department of Chemistry and Biochemistry, University of Texas, Dallas, Richardson, TX (United States); Walker, Amy V.; Chan, Julia Y. [Department of Chemistry and Biochemistry, University of Texas, Dallas, Richardson, TX (United States); Department of Materials Science and Engineering, University of Texas, Dallas, Richardson, TX (United States)

    2017-12-13

    Motivated by the complex structure and properties of giant unit cell intermetallic compounds, a new isostructural Fe analogue of the Dy{sub 117}Co{sub 57}Sn{sub 112} structure type was synthesized. Single crystals of Dy{sub 122}Fe{sub 55}Sn{sub 101} were grown at 1260 C via a Dy-Fe eutectoid flux. The Fe analogue also adopts the space group Fm anti 3m with lattice parameters a = 29.914(9) Aa, V = 26769(23) Aa{sup 3}, and Z = 4. Dy{sub 122}Fe{sub 55}Sn{sub 101} has a large cell volume, structural complexity, and consists of seven Dy, eight Fe, and ten Sn unique crystallographic sites. There are fifteen fully occupied atomic positions, three unique pairs of alternating atomic positions with positional disorder, and seven partially occupied atomic sites. Within this complex unit cell, only approximately half the unique atomic positions are fully occupied with the remainder of the atoms either positionally or occupationally disordered. X-ray photoelectron spectroscopy indicates that the compound contains Dy{sup 3+}, Fe{sup 0}, Fe{sup 2+}, Sn{sup 0}, and Sn{sup 4+}. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. EXAFS study of Mn{sub 1.28}Fe{sub 0.67}P{sub 0.46}Si{sub 0.54} compound with first-order phase transition

    Energy Technology Data Exchange (ETDEWEB)

    L, Yingjie; Huliyageqi, B; Haschaolu, W; Song, Zhiqiang [Inner Mongolia Key Laboratory for Physics and Chemistry of Functional Materials, Physics and Electronic Information College, Inner Mongolia Normal University, Hohhot 010022 (China); Tegus, O, E-mail: tegusph@imnu.edu.cn [Inner Mongolia Key Laboratory for Physics and Chemistry of Functional Materials, Physics and Electronic Information College, Inner Mongolia Normal University, Hohhot 010022 (China); Nakai, Ikuo [Department of Electrical and Electronic Engineering, Tottori University, Tottori 680-8552 (Japan)

    2014-10-15

    Highlights: • We have investigated the Fe and Mn K edge XAFS spectra of the Mn{sub 1.28}Fe{sub 0.67}P{sub 0.46}Si{sub 0.54} compound at 25 K and 295 K. • The site occupation of the Fe and Mn atoms and local structure of Mn{sub 1.28}Fe{sub 0.67}P{sub 0.46}Si{sub 0.54} are determined. • The atomic distances between Fe–Fe in c-plane for the ferromagnetic state are larger than those in the paramagnetic state. - Abstract: The Fe{sub 2}P-type MnFe(P,Si) compounds are investigated by means of magnetic measurements and X-ray absorption fine structure spectroscopy. Magnetic measurements show that the Mn{sub 1.28}Fe{sub 0.67}P{sub 0.46}Si{sub 0.54} compound undergoes a first-order phase transition at the Curie temperature of 254 K. The Fe K-edge and Mn K-edge X-ray absorption fine structure spectra show that Mn atom mainly located at the 3g sites, while the 3f sites are occupied by Fe atoms and Mn atom randomly. The distances between the Fe atom and its nearest neighbor atoms in a triangle Fe–Mn–Fe change from 2.80 Å at 25 K to 2.74 Å at 300 K. On the other hand, the distances between Fe atom and its second neighbor atoms change from 4.06 Å at 25 K to 4.02 Å at 300 K.

  2. The development of the superconducting tetragonal PbO-type FeSe and related compounds

    Energy Technology Data Exchange (ETDEWEB)

    Wu, M.K. [Institute of Physics, Academia Sinica, Nankang, Taipei (China); Department of Physics, National Tsing Hua University, Hsinchu (China); Yeh, K.W.; Huang, T.W.; Chen, T.K.; Luo, J.Y.; Ke, C.T.; Rao, S.M.D. [Institute of Physics, Academia Sinica, Nankang, Taipei (China); Hsu, H.C.; Wang, M.J. [Institute of Astronomy and Astrophysics, Academia Sinica, Taipei (China); Chang, H.H. [Department of Physics, National Tsing Hua University, Hsinchu (China); Moh, M.H. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu (China)

    2010-03-15

    An overview of the recent development of the superconducting FeSe{sub 1-x} and related compounds is presented. Methods to synthesize high purity poly-crystalline samples, single crystals, and thin films with preferred orientation are described. It was found that the effects of chemical doping to the Se-site or Fe-site are rather different. Ionic size of the doping is found to play critical role on the occurrence of superconductivity. We also review the physical properties, including transport, magnetic, and thermal properties. There exist interesting transport anomalies in the resistivity and Hall coefficient at low temperature; and it was found that a structural distortion at low temperature is critical to the occurrence of superconductivity in these materials. However, the exact origin of these observed anomalies are not clear, and the exact pairing symmetry in FeSe-based superconductors is also still in question. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  3. The ferromagnetic Kondo-lattice compound SmFe sub 4 P sub 1 sub 2

    CERN Document Server

    Takeda, N

    2003-01-01

    We report on the magnetic properties of a filled skutterudite compound, SmFe sub 4 P sub 1 sub 2. Magnetic susceptibility and specific heat measurements revealed a ferromagnetic transition at 1.6 K. The temperature dependence of the electrical resistivity exhibits a Kondo-lattice behaviour and the electronic specific heat coefficient attains values as large as 370 mJ mol sup - sup 1 K sup - sup 2. This compound is thereby the first Sm-based heavy-fermion system found with a ferromagnetic ground state. The Kondo temperature is estimated to be about 30 K. (letter to the editor)

  4. Structural and Mössbauer spectroscopy characterization of bulk and nanostructured TiFe{sub 0.5} Ni{sub 0.5}/graphite compounds and their hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Martínez, M. A. R., E-mail: fisicorodriguez@gmail.com; André-Filho, J.; Félix, L. L.; Coaquira, J. A. H.; Garg, V. K.; Oliveira, A. C. [Universidade de Brasília, Instituto de Física, Núcleo de Física Aplicada (Brazil); Mestnik-Filho, J. [Instituto de Pesquisas energéticas e Nucleares, IPEN-CNEN/SP (Brazil)

    2015-06-15

    The structural and hyperfine properties of bulk TiFe{sub 0.5}Ni{sub 0.5} intermetallic and ball-milled TiFe{sub 0.5}Ni{sub 0.5}/graphite compounds and their hydrides have been studied. The bulk and nanostructured TiFe{sub 0.5}Ni{sub 0.5} compounds crystallize in the cubic crystal structure of CsCl (B2). After hydrogenation, the formation of hydrogen-poor phase (∝-phase) and hydride phase (β-phase) have been determined for the bulk compound. However, the formation of the ∝-phase and the hydrogen-richest phase (γ-phase) and other secondary phases have been determined for the ball-milled TiFe{sub 0.5}Ni{sub 0.5}/graphite sample. It has been determined that the ball-milled TiFe{sub 0.5}Ni{sub 0.5}/graphite sample presents a large amount of the γ-phase which indicates that the presence of graphite nearby nanostructured intermetallic grains enhances the absorption of hydrogen. Mossbauer results are consistent with the structural results. Meanwhile, no significant changes in the isomer shift (IS) value has been determined for the α-phase with respect to the intermetallic compound, a strong increase in the IS value has been determined for the β- and γ-phases with respect to the ∝-phase. That increase indicates a decrease of the s-electron density at the Fe nuclei due to the charge transfer from the metal to the nearby hydrogen atoms.

  5. Mechanical properties and electronic structures of Fe-Al intermetallic

    Energy Technology Data Exchange (ETDEWEB)

    Liu, YaHui; Chong, XiaoYu; Jiang, YeHua, E-mail: jiangyehua@kmust.edu.cn; Zhou, Rong; Feng, Jing, E-mail: jingfeng@kmust.edu.cn

    2017-02-01

    Using the first-principles calculations, the elastic properties, anisotropy properties, electronic structures, Debye temperature and stability of Fe-Al (Fe{sub 3}Al, FeAl, FeAl{sub 2}, Fe{sub 2}Al{sub 5} and FeAl{sub 3}) binary compounds were calculated. The formation enthalpy and cohesive energy of these Fe-Al compounds are negative, and show they are thermodynamically stable structures. Fe{sub 2}Al{sub 5} has the lowest formation enthalpy, which shows the Fe{sub 2}Al{sub 5} is the most stable of Fe-Al binary compounds. These Fe-Al compounds display disparate anisotropy due to the calculated different shape of the 3D curved surface of the Young’s modulus and anisotropic index. Fe{sub 3}Al has the biggest bulk modulus with the value 233.2 GPa. FeAl has the biggest Yong’s modulus and shear modulus with the value 296.2 GPa and 119.8 GPa, respectively. The partial density of states, total density of states and electron density distribution maps of the binary Fe-Al binary compounds are analyzed. The bonding characteristics of these Fe-Al binary compounds are mainly combination by covalent bond and metallic bonds. Meanwhile, also exist anti-bond effect. Moreover, the Debye temperatures and sound velocity of these Fe-Al compounds are explored.

  6. Formation and magnetic properties of compounds Er(Fe1-xCox)11.35Nb0.65 (0≤x≤0.4)

    International Nuclear Information System (INIS)

    Wang, K.-Y.; Chen, D.-X.; Arcas, J.; Multigner, M.; Crespo, P.; Vazquez, M.; Hernando, A.

    1997-01-01

    A new series of compounds Er(Fe 1-x Co x ) 11.35 Nb 0.65 were synthesized. For x≤0.4, the element Nb can stabilize the ThMn 12 -type compounds. X-ray diffraction results show that the lattice parameters a and c decrease with the substitution of Co for Fe atoms. With increasing Co content, the Curie temperature increases from T c =507 K for x=0 to T c =904 K for x=0.4. Values of the saturation magnetization at 5 K and 300 K are reported. (orig.)

  7. Magnetic properties of ball-milled TbFe2 and TbFe2B

    Indian Academy of Sciences (India)

    Unknown

    1. Introduction. The RFe2 (R = rare earth) Laves phase compounds are known to possess large cubic anisotropy (Clark et al 1972) and highest Curie temperature (TC) of all RT2 compounds. (T = transition metal). RFe2 ... TbFe2 and TbFe2B were prepared by arc melting the high pure elements (Tb and B, 99⋅9% purity; Fe, ...

  8. Determination of adiabatic temperature change in MnFe(P,Ge) compounds with pulse-field method

    International Nuclear Information System (INIS)

    Trung, N T; Tegus, O; Cam Thanh, D T; Buschow, K H J; Brueck, E; Klaasse, J C P

    2010-01-01

    Fast magnetic measurements performed by means of a 20 T pulse-field magnet provide a good approach for directly monitoring the magnetocaloric effect of the MnFe(P,Ge) compounds. Based on the comparison of magnetization curves obtained either in an adiabatic or isothermal process, we propose that the method introduced by Levitin et al is applicable to determine the adiabatic temperature change for an equivalent field change in first-order magnetic transition materials. More strikingly, experimental results confirm that the first-order nature of the transition in MnFe(P,Ge) alloys is not a limiting factor to the operation frequency of a magnetic refrigerator.

  9. Synthesis and thermoelectric properties of fine-grained FeVSb system half-Heusler compound polycrystals with high phase purity

    International Nuclear Information System (INIS)

    Zou Minmin; Li Jingfeng; Guo Peijun; Kita, Takuji

    2010-01-01

    Nearly single-phased FeVSb half-Heusler compound thermoelectric materials with fine grains of diameter 100-200 nm were prepared from their elemental powders by combining mechanical alloying (MA) and spark plasma sintering. The resultant bulk samples showed a relatively low room-temperature electrical resistivity on the order of 10 μΩm, and a moderate negative Seebeck coefficient with a maximum value of -175 μV K -1 at 300 0 C. It was found that proper excessive addition of V relative to the stoichiometric composition (FeVSb) during MA enhanced the phase purity and hence the power factor of the spark plasma sintered samples, resulting in a large power factor value of 2480 μW m -1 K -2 when the elemental powders were mixed with the composition FeV 1.15 Sb. Its thermal conductivity was significantly reduced mainly due to refined grain sizes, resulting in a high dimensionless figure of merit ZT of 0.31 at a low-to-mid temperature (300 0 C) as for undoped half-Heusler compounds.

  10. The catalytic ozonization of model lignin compounds in the presence of Fe(III) ions

    Science.gov (United States)

    Ben'ko, E. M.; Mukovnya, A. V.; Lunin, V. V.

    2007-05-01

    The ozonization of several model lignin compounds (guaiacol, 2,6-dimethoxyphenol, phenol, and vanillin) was studied in acid media in the presence of iron(III) ions. It was found that Fe3+ did not influence the initial rate of the reactions between model phenols and ozone but accelerated the oxidation of intermediate ozonolysis products. The metal concentration dependences of the total ozone consumption and effective rate constants of catalytic reaction stages were determined. Data on reactions in the presence of oxalic acid as a competing chelate ligand showed that complex formation with Fe3+ was the principal factor that accelerated the ozonolysis of model phenols at the stage of the oxidation of carboxylic dibasic acids and C2 aldehydes formed as intermediate products.

  11. Influence of low Co substitution on magnetoelastic properties of HoFe11Ti intermetallic compound

    International Nuclear Information System (INIS)

    Motevalizadeh, L.; Tajabor, N.; Sanavi Khoshnoud, D.; Fruchart, D.; Pourarian, F.

    2012-01-01

    The thermal expansion and magnetostriction of HoFe 11−x Co x Ti (x=0, 0.3, 0.7 and 1) intermetallic compounds were measured, using the strain gauge method in the temperature range 77–590 K under applied magnetic fields up to 1.5 T. Results show that for samples with x=0 and 0.3, both linear thermal expansion and linear thermal expansion coefficient exhibit anomalies below the Curie temperature. Below room temperature, the spontaneous volume magnetostriction decreases with Co content. For all compounds studied, the anisotropic magnetostriction shows similar behaviour in the measured temperature range. The magnetostriction compensation occurs above room temperature in all samples. The volume magnetostriction shows a linear dependence on the applied field and by approaching the Curie temperature this trend changes to parastrictive behaviour. The results of the spontaneous magnetostriction are discussed based on the local magnetic moment model. The contribution of magnetostriction attributed to the magnetic sublattices R and T (Fe or Co) is discussed. - Highlights: ► Magnetostriction of HoFe 11−x Co x Ti have been measured by using strain gauge method. ► The measurement was carried in 77–590 K under applied magnetic fields up to 1.5 T. ► Spontaneous volume magnetostriction and Invar effect decrease with Co substitution. ► Ho sublattice has negative contribution to spontaneous volume magnetostriction. ► Absolute values of anisotropic magnetostriction decrease slightly with Co content.

  12. Extended x-ray absorption fine structure study of MnFeP0.56Si0.44 compound

    International Nuclear Information System (INIS)

    Li Ying-Jie; Haschaolu W; Wurentuya; Song Zhi-Qiang; Ou Zhi-Qiang; Tegus O; Nakai Ikuo

    2015-01-01

    The MnFeP 0.56 Si 0.44 compound is investigated by x-ray diffraction, magnetic measurements, and x-ray absorption fine structure spectroscopy. It crystallizes in Fe 2 P-type structure with the lattice parameters a = b = 5.9823(0) Å and c = 3.4551(1) Å and undergoes a first-order phase transition at the Curie temperature of 255 K. The Fe K edge and Mn K edge x-ray absorption fine structure spectra show that Mn atoms mainly reside at 3g sites, while 3f sites are occupied by Fe atoms. The distances between the absorbing Fe atom and the first and second nearest neighbor Fe atoms in a 3f-layer shift from 2.65 Å and 4.01 Å in the ferromagnetic state to 2.61 Å and 3.96 Å in the paramagnetic phase. On the other hand, the distance between the 3g-layer and 3f-layer changes a little as 2.66 Å–2.73 Å below the Curie temperature and 2.68 Å–2.75 Å above it. (paper)

  13. Superconductivity and magnetism in the oxypnictides: high field ESR and {mu}SR studies of (La,Gd)FeAsO{sub 1-x}F{sub x} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Muranyi, Ferenc [Physics Institute, University of Zuerich (Switzerland); IFW Dresden (Germany); Alfonsov, Alexey; Kataev, Vladislav; Koehler, Anke; Werner, Jochen; Behr, Guenter; Leps, Norman; Klingeler, Ruediger; Kondrat, Agnieszka; Hess, Christian; Buechner, Bernd [IFW Dresden (Germany); Khasanov, Rustem; Luetkens, Hubertus [Paul Scherrer Institut, Villigen PSI (Switzerland); Klaus, Hans-Henning [IFP, TU Dresden (Germany)

    2009-07-01

    The discovery of a new class of superconducting materials, ReFeAsO{sub 1-x}F{sub x}, stirred up the scientific community. Here we report the Gd{sup 3+} high field ESR study of differently doped (La,Gd)FeAsO{sub 1-x}F{sub x} compounds. In lightly Gd-doped LaFeAsO samples the SDW transition yields line-broadening at the transition temperature, the SDW transition is then suppressed upon F-doping. In the dense compound, GdFeAsO, with SDW transition around 140 K, the Gd-ESR was also studied. With 15% F-doping superconductivity appears at {proportional_to} 21 K. The SDW and SC transitions are clearly seen in ESR and in {mu} SR as well. Surprisingly the reminiscence of the SDW transition of the undoped material (GdFeAsO) was identified in the doped (15% F) compound at lower temperature ({proportional_to} 80 K). This indicates the importance of the the interplay between superconductivity and magnetism in oxypnictides.

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

    NARCIS (Netherlands)

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

    2011-01-01

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

  15. Microfluidic preparation of [18F]FE-SUPPY and [18F]FE-SUPPY:2 - comparison with conventional radiosyntheses

    International Nuclear Information System (INIS)

    Ungersboeck, Johanna; Philippe, Cecile; Mien, Leonhard-Key; Haeusler, Daniela; Shanab, Karem; Lanzenberger, Rupert; Spreitzer, Helmut; Keppler, Bernhard K.; Dudczak, Robert; Kletter, Kurt; Mitterhauser, Markus; Wadsak, Wolfgang

    2011-01-01

    Introduction: Recently, first applications of microfluidic principles for radiosyntheses of positron emission tomography compounds were presented, but direct comparisons with conventional methods were still missing. Therefore, our aims were (1) the set-up of a microfluidic procedure for the preparation of the recently developed adenosine A 3 -receptor tracers [ 18 F]FE-SUPPY [5-(2-[ 18 F]fluoroethyl)2,4-diethyl-3-(ethylsulfanylcarbonyl) -6-phenylpyridine-5-carboxylate] and [ 18 F]FE-SUPPY:2 [5-ethyl-2,4-diethyl-3-((2-[ 18 F]fluoroethyl)sulfanylcarbonyl) -6-phenylpyridine-5-carboxylate] and (2) the direct comparison of reaction conditions and radiochemical yields of the no-carrier-added nucleophilic substitution with [ 18 F]fluoride between microfluidic and conventional methods. Methods: For the determination of optimal reaction conditions within an Advion NanoTek synthesizer, 5-50 μl of precursor and dried [ 18 F]fluoride solution were simultaneously pushed through the temperature-controlled reactor (26 o C-180 o C) with defined reactant bolus flow rates (10-50 μl/min). Radiochemical incorporation yields (RCIYs) and overall radiochemical yields for large-scale preparations were compared with data from conventional batch-mode syntheses. Results: Optimal reaction parameters for the microfluidic set-up were determined as follows: 170 o C, 30-μl/min pump rate per reactant (reaction overall flow rate of 60 μl/min) and 5-mg/ml precursor concentration in the reaction mixture. Applying these optimized conditions, we observed a significant increase in RCIY from 88.2% to 94.1% (P 18 F]FE-SUPPY and that from 42.5% to 95.5% (P 18 F]FE-SUPPY:2 using microfluidic instead of conventional heating. Precursor consumption was decreased from 7.5 and 10 mg to 1 mg per large-scale synthesis for both title compounds, respectively. Conclusion: The direct comparison of radiosyntheses data applying a conventional method and a microfluidic approach revealed a significant increase of RCIY

  16. Crystallographic and magnetic properties of (Nd,Dy)3Fe27.5(Ti,Mo)1.5 compounds

    International Nuclear Information System (INIS)

    Han, S.B.; Liu, X.F.; Lv, J.Y.; Peng, J.; Hao, Y.M.; Li, X.J.; Chen, D.F.; Xue, Y.J.; Li, J.H.; Hu, Z.B.

    2006-01-01

    A systematic study of the formation, structure and magnetic properties of (Nd,Dy) 3 Fe 27.5 (Ti,Mo) 1.5 compounds has been performed. Rietveld analyses of the X-ray patterns of the samples indicate that the concentrations of Ti and Mo affect the formation and structural properties slightly, whereas different rare-earth (Nd and Dy) contents influence them significantly. It is found that high Dy contents make it difficult to form the 3:29-type structures. The Curie temperatures of Nd 2.1 Dy 0.9 Fe 27.5 Ti 1.5- x Mo x decrease monotonically as more Ti was replaced by Mo but their saturation magnetizations remain almost unchanged; in contrast, for Nd 3- y Dy y Fe 27.5 TiMo 0.5 , their saturation magnetizations decrease monotonically with increasing Dy contents while their Curie temperatures are constant

  17. (Sm,Zr(Fe,Co11.0-11.5Ti1.0-0.5 compounds as new permanent magnet materials

    Directory of Open Access Journals (Sweden)

    Tomoko Kuno

    2016-02-01

    Full Text Available We investigated (Sm,Zr(Fe,Co11.0-11.5Ti1.0-0.5 compounds as permanent magnet materials. Good magnetic properties were observed in (Sm0.8Zr0.2(Fe0.75Co0.2511.5Ti0.5 powder containing a limited amount of the α-(Fe, Co phase, including saturation polarization (Js of 1.63 T, an anisotropic field (Ha of 5.90 MA/m at room temperature, and a Curie temperature (Tc of about 880 K. Notably, Js and Ha remained above 1.5 T and 3.70 MA/m, respectively, even at 473 K. The high-temperature magnetic properties of (Sm0.8Zr0.2(Fe0.75Co0.2511.5Ti0.5 were superior to those of Nd2Fe14B.

  18. Electric and magnetic properties of the stage-2 FeBr2 graphite intercalation compound

    International Nuclear Information System (INIS)

    Dube, P A; Barati, M; Ummat, P K; Luke, G; Datars, W R

    2003-01-01

    The stage-2 FeBr 2 graphite intercalation compound (GIC) was prepared by reacting FeBr 2 powder and highly oriented pyrolytic graphite in a bromine atmosphere at 500 deg. C for 40 weeks. The dc magnetization, ac susceptibility, specific heat, resistivity and Hall effect were measured. The GIC is paramagnetic at temperatures above 14.5 K. There is short-range ordering at 14.5 K and longer-range magnetic ordering at 8.5 K. There is a spin glass phase below 3.2 K in which the ac susceptibility is frequency dependent. The in-plane and c-axis resistivities result from in-plane and out-of-plane electron-phonon scattering. The Hall coefficient is independent of temperature between 4.2 and 300 K and is explained by the single-carrier model

  19. Low-temperature heat-capacity study of the U6X (XequivalentMn, Fe, Co, Ni) compounds

    International Nuclear Information System (INIS)

    Yang, K.N.; Maple, M.B.; DeLong, L.E.; Huber, J.G.; Junod, A.

    1989-01-01

    Measurements of the superconducting- and normal-state heat capacity of U 6 X (XequivalentMn, Fe, Co, Ni) compounds have been performed over a temperature range 1 Kapprox. 6 X compounds have strong renormalizations of the free-carrier effective mass m/sup */ in the range 10m/sub e/approx. 6 X heat capacities suggest the presence of high densities of low-energy excitations of undetermined nature. The results are analyzed in terms of models appropriate to heavy-fermion liquids, and anisotropic or strong-coupled superconductors. The U 6 X compounds form a link between relatively low-m/sup */, high-transition-temperature A15 compounds and the more extreme examples of heavy-fermion superconductors such as UBe/sub 13/, UPt 3 , and CeCuSi 2 for which m/sup */∼10 2 m/sub e/. .AE

  20. Incorporation of Mg and Ca into nanostructured Fe2O3 improves Fe solubility in dilute acid and sensory characteristics in foods.

    Science.gov (United States)

    Hilty, Florentine M; Knijnenburg, Jesper T N; Teleki, Alexandra; Krumeich, Frank; Hurrell, Richard F; Pratsinis, Sotiris E; Zimmermann, Michael B

    2011-01-01

    Iron deficiency is one of the most common micronutrient deficiencies worldwide. Food fortification can be an effective and sustainable strategy to reduce Fe deficiency but selection of iron fortificants remains a challenge. Water-soluble compounds, for example, FeSO(4), usually demonstrate high bioavailability but they often cause unacceptable sensory changes in foods. On the other hand, poorly acid-soluble Fe compounds, for example FePO(4), may cause fewer adverse sensory changes in foods but are usually not well bioavailable since they need to be dissolved in the stomach prior to absorption. The solubility and the bioavailability of poorly acid-soluble Fe compounds can be improved by decreasing their primary particle size and thereby increasing their specific surface area. Here, Fe oxide-based nanostructured compounds with added Mg or Ca were produced by scalable flame aerosol technology. The compounds were characterized by nitrogen adsorption, X-ray diffraction, transmission electron microscopy, and Fe solubility in dilute acid. Sensory properties of the Fe-based compounds were tested in 2 highly reactive, polyphenol-rich food matrices: chocolate milk and fruit yoghurt. The Fe solubility of nanostructured Fe(2)O(3) doped with Mg or Ca was higher than that of pure Fe(2)O(3). Since good solubility in dilute acid was obtained despite the inhomogeneity of the powders, inexpensive precursors, for example Fe- and Ca-nitrates, can be used for their manufacture. Adding Mg or Ca lightened powder color, while sensory changes when added to foods were less pronounced than for FeSO(4). The combination of high Fe solubility and low reactivity in foods makes these flame-made nanostructured compounds promising for food fortification. Practical Application: The nanostructured iron-containing compounds presented here may prove useful for iron fortification of certain foods; they are highly soluble in dilute acid and likely to be well absorbed in the gut but cause less severe

  1. Regularity in the formation of compounds in ternary R-Me-Sn systems, R - REM, Me - Fe, Co, Ni, Cu

    International Nuclear Information System (INIS)

    Skolozdra, R.V.; Komarovskaya, L.P.; Koretskaya, O.Eh.

    1992-01-01

    For the ternary alloy systems of (La, Y, Gd, Lu)-Fe-Sn, (Ce, Y, Gd)-Co-Sn, (Ce, Y, Gd, Lu)-Ni-Sn and (Pr, Gd, Lu)-Cu-Sn isothermal sections of phase diagrams were plotted within the range of 670 to 870 K. It was revealed that substitution of transition metal in the kFe-Co-Ni-Cu series led to changes both in a number of ternary stannides and their structural types. A tendency was observed in change of stannide numbers depending on quantity ratio of R and Me components. Crystallochemical analysis of compounds obtained showed that they could be treated as interstitial structures or lsuperstructures with respect to them. The results of magnetic properties measurements were used for explanation of structural features of ternary compounds considered

  2. Description of structure of Fe-Zn intermetalic compounds present in hot-dip galvanized coatings on steel

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2015-10-01

    Full Text Available The article is describing formation, composition, morphology and crystallographic characteristics of intermetalic compounds Fe - Zn present in the coating formed during the process of low-temperature hot-dip galvanizing of carbon steels. In mutual confrontation we introduce older bibliography and results of latest modern researches based on combination of most precise analytical methods.

  3. Crystal-fields at rare-earth sites in R2Fe14B compounds

    International Nuclear Information System (INIS)

    Adam, S.; Adam, G.; Burzo, E.

    1985-12-01

    Crystal-field effects are expected to be important in R 2 Fe 14 B compounds. Within a model-independent approach, it is proved that four distinct rare-earth sites exist with respect to the crystalline electric fields, namely, R(4f; z=0), R(4f; z=0.5 c), R(4g; z=0), and R(4g; z=0.5 c), and relationships are established between the corresponding crystal-fields coefficients. Further, generalized Stevens parametrizations of the crystal field coefficients are derived at three levels of approximation for the interatomic forces inside the crystal. A crystal lattice dressing effect upon the radial electronic integrals is found to occur, the magnitude of which depends on the deviation of the interatomic forces from Coulombian. Finally, computation of crystal-field coefficients in Nd 2 Fe 14 B leads to results which raise questions about the validity of the simple Coulomb point-charge model. (author)

  4. Reaction pathways of model compounds of biomass-derived oxygenates on Fe/Ni bimetallic surfaces

    Science.gov (United States)

    Yu, Weiting; Chen, Jingguang G.

    2015-10-01

    Controlling the activity and selectivity of converting biomass-derivatives to fuels and valuable chemicals is critical for the utilization of biomass feedstocks. There are primarily three classes of non-food competing biomass, cellulose, hemicellulose and lignin. In the current work, glycolaldehyde, furfural and acetaldehyde are studied as model compounds of the three classes of biomass-derivatives. Monometallic Ni(111) and monolayer (ML) Fe/Ni(111) bimetallic surfaces are studied for the reaction pathways of the three biomass surrogates. The ML Fe/Ni(111) surface is identified as an efficient surface for the conversion of biomass-derivatives from the combined results of density functional theory (DFT) calculations and temperature programmed desorption (TPD) experiments. A correlation is also established between the optimized adsorption geometry and experimental reaction pathways. These results should provide helpful insights in catalyst design for the upgrading and conversion of biomass.

  5. Effect of symbiotic compound Fe{sub 2}P{sub 2}O{sub 7} on electrochemical performance of LiFePO{sub 4}/C cathode materials

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shuxin, E-mail: liushuxin88@126.com [School of Chemistry and Chemical Engineering, Mianyang Normal University, Mianyang, Sichuan 621000 (China); Gu, Chunlei [School of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018 (China); Wang, Haibin [School of Chemistry and Chemical Engineering, Mianyang Normal University, Mianyang, Sichuan 621000 (China); Liu, Ruijiang [School of Pharmacy, Jiangsu University, Zhenjiang, Jiangsu 212013 (China); Wang, Hong; He, Jichuan [School of Chemistry and Chemical Engineering, Mianyang Normal University, Mianyang, Sichuan 621000 (China)

    2015-10-15

    In order to study the effect of symbiotic compound Fe{sub 2}P{sub 2}O{sub 7} on electrochemical performance of LiFePO{sub 4}/C cathode materials, the LiFePO{sub 4}/Fe{sub 2}P{sub 2}O{sub 7}/C cathode materials were synthesized by in-situ synthesis method. The phase compositions and microstructures of the products were characterized by X-ray powder diffraction (XRD) and field emission scanning electron microscope (FESEM). Results indicate that the existence of Fe{sub 2}P{sub 2}O{sub 7} does not alter LiFePO{sub 4} crystal structure and the existence of Fe{sub 2}P{sub 2}O{sub 7} decreases the particles size of LiFePO{sub 4}. The electrochemical behavior of cathode materials was analyzed using galvanostatic measurement and cyclic voltammetry (CV). The results show that the existence of Fe{sub 2}P{sub 2}O{sub 7} improves electrochemical performance of LiFePO{sub 4} cathode materials in specific capability and lithium ion diffusion rate. The charge–discharge specific capacity and apparent lithium ion diffusion coefficient increase with Fe{sub 2}P{sub 2}O{sub 7} content and maximizes around the Fe{sub 2}P{sub 2}O{sub 7} content is 5 wt%. It has been had further proved that the Fe{sub 2}P{sub 2}O{sub 7} adding enhances the lithium ion transport to improve the electrochemical performance of LiFePO{sub 4} cathode materials. However, excessive Fe{sub 2}P{sub 2}O{sub 7} will block the electron transfer pathway and affect the electrochemical performances of LiFePO{sub 4} directly. - Graphical abstract: The LiFePO{sub 4}/Fe{sub 2}P{sub 2}O{sub 7}/C cathode materials were synthesized by in-situ synthesis method. The existence of Fe{sub 2}P{sub 2}O{sub 7} does not alter LiFePO{sub 4} crystal structure and the existence of Fe{sub 2}P{sub 2}O{sub 7} decreases the particles size of LiFePO{sub 4}. The charge–discharge specific capacity and apparent lithium ion diffusion coefficient increase with Fe{sub 2}P{sub 2}O{sub 7} content. However, excessive Fe{sub 2}P{sub 2}O{sub 7} will

  6. Ammonium iron(III phosphate(V fluoride, (NH40.5[(NH40.375K0.125]FePO4F, with ammonium partially substituted by potassium

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2009-01-01

    Full Text Available The title compound, ammonium potassium iron(III phosphate fluoride, (NH40.875K0.125FePO4F, is built from zigzag chains ∞1{[FeO4F2]7−}, with Fe3+ in a distorted octahedral coordination, extending along both the [011] and [0overline{1}1] directions. These chains are made up of alternating trans-[FeO4F2] and cis-[FeO4F2] octahedra via shared F-atom corners, and are linked by PO4 tetrahedra, resulting in an open-framework structure with channels along the [010] and [100] directions. There are two crystallographically independent ammonium sites: one in the [010] channels and the other, partially substituted by K+ ions, in the [100] channels. The ammonium in the [010] channels is fixed to the framework via eight hydrogen bonds (six N—H...O and two N—H...F.

  7. A study on magnetoelastic properties of Tb3 (Fe28-xCox) V1.0 (x=0, 3, 6) compounds

    International Nuclear Information System (INIS)

    Gholizadeh, A.; Tajabor, N.; Pourarian, F.

    2012-01-01

    In this work, The magnetoelastic properties of polycrystalline samples of Tb 3 (Fe 28-x Co x ) V 1.0 (x=0, 3, 6) intermetallic compounds are investigated by means of linear thermal expansion and magnetostriction measurements in the temperature range of 77-515 K under applied magnetic fields up to 1.5 T. The linear thermal expansion increases with the Co content. The well-defined anomalies observed in the linear thermal expansion coefficients for Tb 3 (Fe 28-x Co x ) V 1.0 (x=0, 3, 6) compounds are associated with the magnetic ordering temperature for x=0 and spin reorientation temperatures for x=3, 6. Below transition temperatures, the value of the longitudinal magnetostriction (λ Pa ) at 1.6 T increases with Co content.

  8. Vibrational properties of stannite and kesterite type compounds: Raman scattering analysis of Cu2(Fe,Zn)SnS4

    International Nuclear Information System (INIS)

    Fontané, X.; Izquierdo-Roca, V.; Saucedo, E.; Schorr, S.; Yukhymchuk, V.O.; Valakh, M.Ya.; Pérez-Rodríguez, A.; Morante, J.R.

    2012-01-01

    Highlights: ► Analysis of main and weaker Raman peaks from Cu 2 FeZnS 4 and Cu 2 ZnSnS 4 compounds. ► Identification of a cation disorder induced Raman peak in Cu 2 ZnSnS 4 . ► Analysis of spectral features of main Raman peaks from Cu 2 (Fe,Zn)SnS 4 . - Abstract: This work reports the analysis of the vibrational properties of stannite–kesterite Cu 2 (Fe,Zn)SnS 4 compounds that has been performed by Raman scattering measurements. The detailed analysis of the experimental spectra has allowed determining the frequency and symmetry assignment of the main and weaker peaks from both stannite Cu 2 FeSnS 4 (CFTS) and kesterite Cu 2 ZnSnS 4 (CZTS) phases. The measurements performed in the kesterite CZTS samples have also revealed the presence of local inhomogeneities that are characterised by an additional peak in the spectra at about 331 cm −1 . This peak has been related to the presence in these local regions of a high degree of disorder in the cation sublattice, in agreement with previous neutron diffraction analysis in similar samples. Finally, the spectra from the solid solution alloys show a one-mode behaviour of the main A/A 1 peak with the chemical composition.

  9. A study of nitrogenation of a NdFe12-xMox compound by in situ neutron powder diffraction

    International Nuclear Information System (INIS)

    Loong, C.; Short, S.M.; Lin, J.; Ding, Y.

    1998-01-01

    The effects on the crystal lattice of a NdFe 12-x Mo x (x congruent 1.7) during controlled nitrogenation over the 25 endash 600 degree C temperature range were studied by neutron powder diffraction. Prior to nitrogenation the sample contained a major phase of NdFe 10.3 Mo 1.7 and a minor phase (∼12vol%) of bcc-Fe. The sample inside the furnace was connected to a closed volume of ultrapure nitrogen gas while neutron data were collected over regular time intervals during sequential heating. Substantial nitrogen absorption occurred between 500 and 600 degree C. During the nitrogenation process the NdFe 12-x Mo x N y lattice expanded while the bcc-Fe lattice contracted. An increasing decomposition of the compound into bcc-Fe at 600 degree C was observed. The average size of the NdFe 12-x Mo x N y crystalline grains decreased starting at ∼300 degree C, reaching a minimum at ∼500 degree C and then increased markedly at higher temperatures. The development of lattice strains, on the other hand, showed an opposite trend, i.e., a maximum at 500 degree C. copyright 1998 American Institute of Physics

  10. Volume and overlap effects in the hyperfine interactions on the 57Fe2+ in quasi-ionics iron compounds

    International Nuclear Information System (INIS)

    Costa Junior, M.I. da.

    1976-01-01

    Several nearly ionic ferrous compounds for which one expects charge transfer to be negligible, are studied. A cluster model in which the multi centered wave function is described in terms of overlap only, is assumed. A definite correlation between the total Fe 3d overlap with the ligand orbitals and delta is found, but no such correlation for ΔE sub(Q). The former result indicates that 3d-3s shielding may be important in these cases while the latter result leads to the belief that ΔE sub(Q) may not be completely described by a cluster model. 57 Fe Moessbauer effect measurements are made in Fe substituted carbonates (M sub(1-x) Fe sub(x))CO 3 , to help clarify these results, with M = Ca, Cd, Co, Fe, Mn, Zn, Mg; all of which are isostructural. An analysis of the data show that in this case (and that of the Fe substituted fluorides) the trends observed can be correlated to a volume effect due to the different site sizes for the Fe 2+ ion. It is shown that in the case of the fluorides, the effects are identical with pressure induced effects if local distortions are taken into account [pt

  11. Interplay of magnetism and superconductivity in the compressed Fe-ladder compound BaFe2Se3

    Energy Technology Data Exchange (ETDEWEB)

    Ying, Jianjun; Lei, Hechang; Petrovic, Cedomir; Xiao, Yuming; Struzhkin, Viktor V. (BNL); (CIW)

    2017-06-01

    High pressure resistance, susceptibility, and Fe K β x-ray emission spectroscopy measurements were performed on Fe-ladder compound BaFe 2 Se 3 . Pressure-induced superconductivity was observed which is similar to the previously reported superconductivity in the BaFe 2 S 3 samples. The slope of local magnetic moment versus pressure shows an anomaly across the insulator-metal transition pressure in the BaFe 2 Se 3 samples. The local magnetic moment is continuously decreasing with increasing pressure, and the superconductivity appears only when the local magnetic moment value is comparable to the one in the iron-pnictide superconductors. Our results indicate that the compressed BaFe 2 C h 3 ( C h = S , Se) is a new family of iron-based superconductors. Despite the crystal structures completely different from the known iron-based superconducting materials, the magnetism in this Fe-ladder material plays a critical role in superconductivity. This behavior is similar to the other members of iron-based superconducting materials.

  12. Microfluidic preparation of [{sup 18}F]FE-SUPPY and [{sup 18}F]FE-SUPPY:2 - comparison with conventional radiosyntheses

    Energy Technology Data Exchange (ETDEWEB)

    Ungersboeck, Johanna [Department of Nuclear Medicine, Medical University of Vienna, A-1090 Vienna (Austria); Department of Inorganic Chemistry, University of Vienna, A-1090 Vienna (Austria); Philippe, Cecile [Department of Nuclear Medicine, Medical University of Vienna, A-1090 Vienna (Austria); Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, A-1090 Vienna (Austria); Mien, Leonhard-Key [Department of Nuclear Medicine, Medical University of Vienna, A-1090 Vienna (Austria); Haeusler, Daniela [Department of Nuclear Medicine, Medical University of Vienna, A-1090 Vienna (Austria); Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, A-1090 Vienna (Austria); Shanab, Karem [Department of Nuclear Medicine, Medical University of Vienna, A-1090 Vienna (Austria); Department of Drug and Natural Product Synthesis, University of Vienna, A-1090 Vienna (Austria); Lanzenberger, Rupert [Department of Psychiatry and Psychotherapy, Medical University of Vienna, A-1090 Vienna (Austria); Spreitzer, Helmut [Department of Drug and Natural Product Synthesis, University of Vienna, A-1090 Vienna (Austria); Keppler, Bernhard K. [Department of Inorganic Chemistry, University of Vienna, A-1090 Vienna (Austria); Dudczak, Robert; Kletter, Kurt [Department of Nuclear Medicine, Medical University of Vienna, A-1090 Vienna (Austria); Mitterhauser, Markus [Department of Nuclear Medicine, Medical University of Vienna, A-1090 Vienna (Austria); Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, A-1090 Vienna (Austria); Hospital Pharmacy, General Hospital of Vienna, A-1090 Vienna (Austria); Wadsak, Wolfgang, E-mail: wolfgang.wadsak@meduniwien.ac.a [Department of Nuclear Medicine, Medical University of Vienna, A-1090 Vienna (Austria); Department of Inorganic Chemistry, University of Vienna, A-1090 Vienna (Austria)

    2011-04-15

    Introduction: Recently, first applications of microfluidic principles for radiosyntheses of positron emission tomography compounds were presented, but direct comparisons with conventional methods were still missing. Therefore, our aims were (1) the set-up of a microfluidic procedure for the preparation of the recently developed adenosine A{sub 3}-receptor tracers [{sup 18}F]FE-SUPPY [5-(2-[{sup 18}F]fluoroethyl)2,4-diethyl-3-(ethylsulfanylcarbonyl) -6-phenylpyridine-5-carboxylate] and [{sup 18}F]FE-SUPPY:2 [5-ethyl-2,4-diethyl-3-((2-[{sup 18}F]fluoroethyl)sulfanylcarbonyl) -6-phenylpyridine-5-carboxylate] and (2) the direct comparison of reaction conditions and radiochemical yields of the no-carrier-added nucleophilic substitution with [{sup 18}F]fluoride between microfluidic and conventional methods. Methods: For the determination of optimal reaction conditions within an Advion NanoTek synthesizer, 5-50 {mu}l of precursor and dried [{sup 18}F]fluoride solution were simultaneously pushed through the temperature-controlled reactor (26{sup o}C-180{sup o}C) with defined reactant bolus flow rates (10-50 {mu}l/min). Radiochemical incorporation yields (RCIYs) and overall radiochemical yields for large-scale preparations were compared with data from conventional batch-mode syntheses. Results: Optimal reaction parameters for the microfluidic set-up were determined as follows: 170{sup o}C, 30-{mu}l/min pump rate per reactant (reaction overall flow rate of 60 {mu}l/min) and 5-mg/ml precursor concentration in the reaction mixture. Applying these optimized conditions, we observed a significant increase in RCIY from 88.2% to 94.1% (P<.0001, n{>=}11) for [{sup 18}F]FE-SUPPY and that from 42.5% to 95.5% (P<.0001, n{>=}5) for [{sup 18}F]FE-SUPPY:2 using microfluidic instead of conventional heating. Precursor consumption was decreased from 7.5 and 10 mg to 1 mg per large-scale synthesis for both title compounds, respectively. Conclusion: The direct comparison of radiosyntheses data

  13. 57Fe Moessbauer and magnetic studies of ErFe12-xNbx

    International Nuclear Information System (INIS)

    Wang, J L; Campbell, S J; Cadogan, J M; Tegus, O; Edge, A V J

    2005-01-01

    The structural and magnetic properties of ErFe 12-x Nb x compounds (x 0.6, 0.7 and 0.8) have been investigated by x-ray diffraction, ac susceptibility and dc magnetization measurements and 57 Fe Moessbauer spectroscopy. Refinements of the x-ray diffraction patterns show that the Nb atoms preferentially occupy the 8i sites; this can be understood in the terms of enthalpy effects and differences in the metallic radii. The average Fe-Fe distance at the different sites is found to behave as d Fe-Fe (8i)> d Fe-Fe (8j)> d Fe-Fe (8f). The unit cell volume increases slightly with increasing Nb content, consistent with the larger radius of Nb compared with Fe. A spin reorientation from easy-axis at room temperature to easy-cone at low temperatures has been detected for all compounds. The spin reorientation temperatures T sr in ErFe 12-x Nb x compounds remain essentially unchanged (T sr ∼42-44 K) with increasing Nb concentration, whereas a significant decrease in T sr (T sr1 ∼236-204 K; T sr2 ∼154-94 K) is obtained in DyFe 12-x Nb x from x = 0.6 to 0.8. This can be understood by taking the different crystal-field terms responsible for the spin reorientation in the two systems into account. We find that the spin-reorientation process is particularly sensitive to the sixth-order term B 60 O 60 of the crystal field acting on the Er 3+ ion, due to its large and positive value of γ J . 57 Fe hyperfine interaction parameters and magnetic moments values have been determined for the 8i, 8j and 8f sites from the Moessbauer spectra. The weighted average 57 Fe hyperfine field values were found to follow a T 2 dependence; this suggests that a single-particle excitation mechanism is responsible for reduction of the 3d-sublattice magnetization with increasing temperature

  14. Prediction study of structural, elastic and electronic properties of FeMP (M = Ti, Zr, Hf) compounds

    Science.gov (United States)

    Tanto, A.; Chihi, T.; Ghebouli, M. A.; Reffas, M.; Fatmi, M.; Ghebouli, B.

    2018-06-01

    First principles calculations are applied in the study of FeMP (M = Ti, Zr, Hf) compounds. We investigate the structural, elastic, mechanical and electronic properties by combining first-principles calculations with the CASTEP approach. For ideal polycrystalline FeMP (M = Ti, Zr, Hf) the shear modulus, Young's modulus, Poisson's ratio, elastic anisotropy indexes, Pugh's criterion, elastic wave velocities and Debye temperature are also calculated from the single crystal elastic constants. The shear anisotropic factors and anisotropy are obtained from the single crystal elastic constants. The Debye temperature is calculated from the average elastic wave velocity obtained from shear and bulk modulus as well as the integration of elastic wave velocities in different directions of the single crystal.

  15. Mechanisms for Fe(III) oxide reduction in sedimentary environments

    Science.gov (United States)

    Nevin, Kelly P.; Lovely, Derek R.

    2002-01-01

    Although it was previously considered that Fe(III)-reducing microorganisms must come into direct contact with Fe(III) oxides in order to reduce them, recent studies have suggested that electron-shuttling compounds and/or Fe(III) chelators, either naturally present or produced by the Fe(III)-reducing microorganisms themselves, may alleviate the need for the Fe(III) reducers to establish direct contact with Fe(III) oxides. Studies with Shewanella alga strain BrY and Fe(III) oxides sequestered within microporous beads demonstrated for the first time that this organism releases a compound(s) that permits electron transfer to Fe(III) oxides which the organism cannot directly contact. Furthermore, as much as 450 w M dissolved Fe(III) was detected in cultures of S. alga growing in Fe(III) oxide medium, suggesting that this organism releases compounds that can solublize Fe(III) from Fe(III) oxide. These results contrast with previous studies, which demonstrated that Geobacter metallireducens does not produce electron-shuttles or Fe(III) chelators. Some freshwater aquatic sediments and groundwaters contained compounds, which could act as electron shuttles by accepting electrons from G. metallireducens and then transferring the electrons to Fe(III). However, other samples lacked significant electron-shuttling capacity. Spectroscopic studies indicated that the electron-shuttling capacity of the waters was not only associated with the presence of humic substances, but water extracts of walnut, oak, and maple leaves contained electron-shuttling compounds did not appear to be humic substances. Porewater from a freshwater aquatic sediment and groundwater from a petroleum-contaminated aquifer contained dissolved Fe(III) (4-16 w M), suggesting that soluble Fe(III) may be available as an electron acceptor in some sedimentary environments. These results demonstrate that in order to accurately model the mechanisms for Fe(III) reduction in sedimentary environments it will be necessary

  16. Thermodynamic study of NaFe complex oxides. High temperature properties of Na sub 5 FeO sub 4 and Na sub 3 FeO sub 3

    CERN Document Server

    Furukawa, T

    2002-01-01

    In order to contribute the investigation into corrosion mechanism of the structural materials by leakage sodium, thermodynamic study of Na-Fe complex oxides formed by the reactions was carried out. Na sub 5 FeO sub 4 and Na sub 3 FeO sub 3 were used as the sample. Its high temperature properties (i.e. melting, solidification and transformation) were observed by Differential Scanning Calorimetry, DSC. Moreover, the original test named 'melting point confirmation test' was performed for the observation of traces of melting and solidification after the tests. Following contents have been obtained by this study. (1) Na sub 5 FeO sub 4 was stably as the solid without phase transformation and melting until 800degC. However, the compound was showing a tendency to change into Na sub 4 FeO sub 3 with temperature increasing under the low oxygen potential. (2) The stability of Na sub 3 FeO sub 3 is the same as that of Na sub 5 FeO sub 4 until 700degC. Over the temperature, the compound was changed differential compound ...

  17. Magnetic and magnetocaloric properties of amorphous Y{sub 3}Fe{sub 5}O{sub 12} compound

    Energy Technology Data Exchange (ETDEWEB)

    Nóbrega, E.P., E-mail: pilad@cbpf.br; Costa, S.S.; Alvarenga, T.S.T.; Alho, B.P.; Caldas, A.; Ribeiro, P.O.; Sousa, V.S.R de; Oliveira, N.A. de; Ranke, P.J. von

    2017-01-15

    We report a theoretical model formed by two coupled magnetic sublattices of localized spins in the presence of an applied magnetic field to investigate the magnetic characteristics and magnetocaloric properties of amorphous yttrium iron garnet. The magnetic state equation is based on Handrich–Kobe´s theory, where the amorphization is taken into account by introducing fluctuations in the exchange parameters. Experimental results report that Y{sub 3}Fe{sub 5}O{sub 12} presents a structural phase transition from crystalline to amorphous caused by a variation of external pressure. This phase transition on Y{sub 3}Fe{sub 5}O{sub 12} leads to interesting results in the magnetic properties and magnetocaloric quantities. - Highlights: • Study of magnetic and magnetocaloric properties of amorphous Y{sub 3}Fe{sub 5}O{sub 12} compound. • Theoretical model formed by two coupled magnetic sublattices of localized spins in the presence of an applied magnetic field. • The influence of crystalline/amorphous transition on the magnetocaloric effect.

  18. Active Iron Sites of Disordered Mesoporous Silica Catalyst FeKIL-2 in the Oxidation of Volatile Organic Compounds (VOC

    Directory of Open Access Journals (Sweden)

    Mojca Rangus

    2014-05-01

    Full Text Available Iron-functionalized disordered mesoporous silica (FeKIL-2 is a promising, environmentally friendly, cost-effective and highly efficient catalyst for the elimination of volatile organic compounds (VOCs from polluted air via catalytic oxidation. In this study, we investigated the type of catalytically active iron sites for different iron concentrations in FeKIL-2 catalysts using advanced characterization of the local environment of iron atoms by a combination of X-ray Absorption Spectroscopy Techniques (XANES, EXAFS and Atomic-Resolution Scanning Transmission Electron Microscopy (AR STEM. We found that the molar ratio Fe/Si ≤ 0.01 leads to the formation of stable, mostly isolated Fe3+ sites in the silica matrix, while higher iron content Fe/Si > 0.01 leads to the formation of oligonuclear iron clusters. STEM imaging and EELS techniques confirmed the existence of these clusters. Their size ranges from one to a few nanometers, and they are unevenly distributed throughout the material. The size of the clusters was also found to be similar, regardless of the nominal concentration of iron (Fe/Si = 0.02 and Fe/Si = 0.05. From the results obtained from sample characterization and model catalytic tests, we established that the enhanced activity of FeKIL-2 with the optimal Fe/Si = 0.01 ratio can be attributed to: (1 the optimal concentration of stable isolated Fe3+ in the silica support; and (2 accelerated diffusion of the reactants in disordered mesoporous silica (FeKIL-2 when compared to ordered mesoporous silica materials (FeSBA-15, FeMCM-41.

  19. Electric and magnetic properties of the stage-2 FeBr{sub 2} graphite intercalation compound

    Energy Technology Data Exchange (ETDEWEB)

    Dube, P A; Barati, M; Ummat, P K; Luke, G; Datars, W R [Department of Physics and Astronomy, McMaster University, Hamilton, ON (Canada)

    2003-01-22

    The stage-2 FeBr{sub 2} graphite intercalation compound (GIC) was prepared by reacting FeBr{sub 2} powder and highly oriented pyrolytic graphite in a bromine atmosphere at 500 deg. C for 40 weeks. The dc magnetization, ac susceptibility, specific heat, resistivity and Hall effect were measured. The GIC is paramagnetic at temperatures above 14.5 K. There is short-range ordering at 14.5 K and longer-range magnetic ordering at 8.5 K. There is a spin glass phase below 3.2 K in which the ac susceptibility is frequency dependent. The in-plane and c-axis resistivities result from in-plane and out-of-plane electron-phonon scattering. The Hall coefficient is independent of temperature between 4.2 and 300 K and is explained by the single-carrier model.

  20. Behavior of methyl orange and orange 10 (orange G) in the presence of hydrotalcite type compounds of Mg/Al and Mg/Fe; Comportamiento de naranja de metilo y naranja 10 (orange G) en presencia de compuestos tipo hidrotalcita de mg/Al y Mg/Fe

    Energy Technology Data Exchange (ETDEWEB)

    Cruz N, G.

    2015-07-01

    This work is focused on studying the sorption capacity of methyl orange dye (Nm) and orange 10 (N-10) in the presence of hydrotalcite type compounds of Mg/Al and Mg/Fe uncalcined and calcined previously at 500 degrees Celsius. Sorption isotherms were determined and the study of the kinetics of sorption was performed. The materials were characterized before and after sorption processes of these dyes by X-ray diffraction, scanning electron microscopy, the specific surface area determination by the Brunauer-Emmett-Teller method, thermogravimetry coupled to mass and infrared spectrometry. The hydrotalcite type compounds reported in this paper were prepared in the laboratory and their acronyms are: HTMgAlG1, HTMgAlMO, HTMgFeG1 and HTMgFeG2. Note that in this work the best conditions for preparing compounds of Mg/Fe were found. From patterns of X-ray diffraction was identified the typical crystal structure of the hydrotalcite type compounds. By scanning electron microscopy the morphology could be determined in the form of flakes characteristics of these compounds. Likewise with elemental analysis of energy dispersive X-ray spectroscopy the presence of Mg, Al, Fe and C, elements of interest for this study was determined. The compounds presented a specific surface area relatively high from 80 to 120 m{sup 2}/g. Thermogravimetry results presented spectra of mass loss very characteristic associated to water losses, dehydroxylation and decarboxylation. The characteristic bands of water and carbonate were assigned by infrared spectroscopy and the bands corresponding to the dyes sulfonates were identified only for the calcined materials. The sorption capacities found of these compounds were as follows: for Nm in the compound HTMgAlG1 uncalcined was 17.82 mg/g for an initial concentration of 200 mg/L and for calcined (HTMgAlMOcal) of 99.8 mg/g with and initial concentration of 1000 mg/L. Moreover, the sorption capacity of the dye N-10 in this same material was 17.92 mg/g and 99

  1. The formation of light absorbing insoluble organic compounds from the reaction of biomass burning precursors and Fe(III)

    Science.gov (United States)

    Lavi, Avi; Lin, Peng; Bhaduri, Bhaskar; Laskin, Alexander; Rudich, Yinon

    2017-04-01

    Dust particles and volatile organic compounds from fuel or biomass burning are two major components that affect air quality in urban polluted areas. We characterized the products from the reaction of soluble Fe(III), a reactive transition metal originating from dust particles dissolution processes, with phenolic compounds , namely, guaiacol, syringol, catechol, o- and p- cresol that are known products of incomplete fuel and biomass combustion but also from other natural sources such as humic compounds degradation. We found that under acidic conditions comparable to those expected on a dust particle surface, phenolic compounds readily react with dissolved Fe(III), leading to the formation of insoluble polymeric compounds. We characterized the insoluble products by x-ray photoelectron microscopy, UV-Vis spectroscopy, mass spectrometry, elemental analysis and thermo-gravimetric analysis. We found that the major chromophores formed are oligomers (from dimers to pentamers) of the reaction precursors that efficiently absorb light between 300nm and 500nm. High variability of the mass absorption coefficient of the reaction products was observed with catechol and guaiacol showing high absorption at the 300-500nm range that is comparable to that of brown carbon (BrC) from biomass burning studies. The studied reaction is a potential source for the in-situ production of secondary BrC material under dark conditions. Our results suggest a reaction path for the formation of bio-available iron in coastal polluted areas where dust particles mix with biomass burning pollution plumes. Such mixing can occur, for instance in the coast of West Africa or North Africa during dust and biomass burning seasons

  2. TbNb6Sn6: the first ternary compound from the rare earth–niobium–tin system

    Directory of Open Access Journals (Sweden)

    Viktor Hlukhyy

    2010-12-01

    Full Text Available The title compound, terbium hexaniobium hexastannide, TbNb6Sn6, is the first ternary compound from the rare earth–niobium–tin system. It has the HfFe6Ge6 structure type, which can be analysed as an intergrowth of the Zr4Al3 and CaCu5 structures. All the atoms lie on special positions; their coordination geometries and site symmetries are: Tb (dodecahedron 6/mmm; Nb (distorted icosahedron 2mm; Sn (Frank–Caspar polyhedron, CN = 14–15 6mm and overline{6}m2; Sn (distorted icosahedron overline{6}m2. The structure contains a graphite-type Sn network, Kagome nets of Nb atoms, and Tb atoms alternating with Sn2 dumbbells in the channels.

  3. Magnetic structure of the magnetocaloric compound AlFe{sub 2}B{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Cedervall, Johan, E-mail: johan.cedervall@kemi.uu.se [Department of Chemistry – Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala (Sweden); Andersson, Mikael Svante; Sarkar, Tapati [Department of Engineering Sciences, Uppsala University, Box 534, 751 21 Uppsala (Sweden); Delczeg-Czirjak, Erna K. [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Bergqvist, Lars [Department of Materials and Nano Physics and Swedish e-Science Research Centre (SeRC), Royal Institute of Technology (KTH), Electrum 229, SE-164 40 Kista (Sweden); Hansen, Thomas C. [Institut Laue-Langevin, B.P. 156, Grenoble Cedex 9, 38042 France (France); Beran, Premysl [Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Rez, 25068 Czech Republic (Czech Republic); Nordblad, Per [Department of Engineering Sciences, Uppsala University, Box 534, 751 21 Uppsala (Sweden); Sahlberg, Martin [Department of Chemistry – Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala (Sweden)

    2016-04-15

    The crystal and magnetic structures of AlFe{sub 2}B{sub 2} have been studied with a combination of X-ray and neutron diffraction and electronic structure calculations. The magnetic and magnetocaloric properties have been investigated by magnetisation measurements. The samples have been produced using high temperature synthesis and subsequent heat treatments. The compound crystallises in the orthorhombic crystal system Cmmm and it orders ferromagnetically at 285 K through a second order phase transition. At temperatures below the magnetic transition the magnetic moments align along the crystallographic a-axis. The magnetic entropy change from 0 to 800 kA/m was found to be −1.3 J/K kg at the magnetic transition temperature. - Graphical abstract: The magnetic structure of AlFe{sub 2}B{sub 2} has been investigated using neutron diffraction and the magnetic spins have been found to align ferromagnetically along the crystallographic a-axis. - Highlights: • The crystal and magnetic structures of AlFe{sub 2}B{sub 2} have been studied. • Orders ferromagnetically at 285 K via a second order phase transition. • The magnetic moments are found to be aligned along the crystallographic a-axis. • The magnetic entropy change from 0 to 800 kA/m was found to be −1.3 J/K kg.

  4. Structure and magnetic properties of (Nd1-xErx)3Fe25Cr4.0 (0 ≤ x ≤ 0.8) compounds

    International Nuclear Information System (INIS)

    Luo Hongzhi; Jia Lin; Li Yangxian; Meng Fanbin; Shen Jiang; Chen Nanxian; Wu Guangheng; Yang Fuming

    2004-01-01

    The structure and magnetic properties of (Nd 1-x Er x ) 3 Fe 25 Cr 4.0 compounds with x = 0-0.8 have been investigated using x-ray powder diffraction (XRD) and magnetic measurements. It has been found that all the compounds crystallize in a Nd 3 (Fe,Ti) 29 -type structure. Substitution of Er for Nd leads to a contraction of the unit-cell volume. The Curie temperature, T c , and the saturation magnetization, M s , of (Nd 1-x Er x ) 3 Fe 25 Cr 4.0 decrease monotonically with increasing Er content. The easy magnetization direction (EMD) of Nd 3 Fe 25 Cr 4.0 at room temperature is close to the [040] direction but may be a little out of the basal plane. With increasing Er content, the EMD changes closer to the [40-2] direction and the tilt angle increases. Both the XRD patterns and ac susceptibility indicate the appearance of a spin reorientation for x = 0-0.4 as the temperature decreases from room temperature to 77 K. The spin reorientation temperature, T sr , increases monotonically with increasing Er content from 158 K for x = 0 to 198 K for x = 0.4. A first order magnetization process (FOMP) occurs for all the compounds, and the critical field of the FOMP decreases with increasing Er content from 6.6 T for x = 0 to 2.0 T for x = 0.7

  5. First principles calculations of the magnetic and hyperfine properties of Fe/N/Fe and Fe/O/Fe multilayers in the ground state of cohesive energy

    Science.gov (United States)

    dos Santos, A. V.; Samudio Pérez, C. A.; Muenchen, D.; Anibele, T. P.

    2015-01-01

    The ground state properties of Fe/N/Fe and Fe/O/Fe multilayers were investigated using the first principles calculations. The calculations were performed using the Linearized Augmented Plane Wave (LAPW) method implemented in the Wien2k code. A supercell consisting of one layer of nitride (or oxide) between two layers of Fe in the bcc structure was used to model the structure of the multilayer. The research in new materials also stimulated theoretical and experimental studies of iron-based nitrides due to their variety of structural and magnetic properties for the potential applications as in high strength steels and for high corrosion resistance. It is obvious from many reports that magnetic iron nitrides such as γ-Fe4N and α-Fe16N2 have interesting magnetic properties, among these a high magnetisation saturation and a high density crimp. However, although Fe-N films and multilayers have many potential applications, they can be produced in many ways and are being extensively studied from the theoretical point of view there is no detailed knowledge of their electronic structure. Clearly, efforts to understand the influence of the nitrogen atoms on the entire electronic structure are needed as to correctly interpret the observed changes in the magnetic properties when going from Fe-N bulk compounds to multilayer structures. Nevertheless, the N atoms are not solely responsible for electronics alterations in solid compounds. Theoretical results showed that Fe4X bulk compounds, where X is a variable atom with increasing atomic number (Z), the nature of bonding between X and adjacent Fe atoms changes from more covalent to more ionic and the magnetic moments of Fe also increase for Z=7, i.e. N. This is an indicative that atoms with a Z number higher than 7, i.e., O, can produce several new alterations in the entire magnetic properties of Fe multilayers. This paper presents the first results of an ab-initio electronic structure calculations, performed for Fe-N and Fe

  6. Structural, electronic, magnetic, half-metallic, mechanical, and thermodynamic properties of the quaternary Heusler compound FeCrRuSi: A first-principles study.

    Science.gov (United States)

    Wang, Xiaotian; Khachai, Houari; Khenata, Rabah; Yuan, Hongkuan; Wang, Liying; Wang, Wenhong; Bouhemadou, Abdelmadjid; Hao, Liyu; Dai, Xuefang; Guo, Ruikang; Liu, Guodong; Cheng, Zhenxiang

    2017-11-23

    In this paper, we have investigated the structural, electronic, magnetic, half-metallic, mechanical, and thermodynamic properties of the equiatomic quaternary Heusler (EQH) compound FeCrRuSi using the density functional theory (DFT) and the quasi-harmonic Debye model. Our results reveal that FeCrRuSi is a half-metallic material (HMM) with a total magnetic moment of 2.0 μ B in agreement with the well-known Slater-Pauling rule M t  = Z t  - 24. Furthermore, the origin of the half-metallic band gap in FeCrRuSi is well studied through a schematic diagram of the possible d-d hybridization between Fe, Cr and Ru elements. The half-metallic behavior of FeCrRuSi can be maintained in a relatively wide range of variations of the lattice constant (5.5-5.8 Å) under uniform strain and the c/a ratio (0.96-1.05) under tetragonal distortion. The calculated phonon dispersion, cohesive and formation energies, and mechanical properties reveal that FeCrRuSi is stable with an EQH structure. Importantly, the compound of interest has been prepared and is found to exist in an EQH type structure with the presence of some B2 disorder. Moreover, the thermodynamic properties, such as the thermal expansion coefficient α, the heat capacity C V , the Grüneisen constant γ, and the Debye temperature Θ D are calculated.

  7. Hydrothermal synthesis, structural elucidation, spectroscopic studies, thermal behavior and luminescence properties of a new 3-d compound: FeAlF2(C10H8N2)(HPO4)2(H2O)

    Science.gov (United States)

    Bouzidia, Nabaa; Salah, Najet; Hamdi, Besma; Ben Salah, Abdelhamid

    2017-04-01

    The study of metal phosphate has been a proactive field of research thanks to its applied and scientific importance, especially in terms of the development of optical devices such as solid state lasers as well as optical fibers. The present paper seeks to investigate the synthesis, crystal structure, elemental analysis and properties of FeAlF2(C10H8N2)(HPO4)2(H2O) compound investigated by spectroscopic studies (FT-IR and FT-Raman), thermal behavior and luminescence. The Hirshfeld surface analysis and 2-D fingerprint plot have been performed to explore the behavior of these weak interactions and crystal cohesion. This investigation shows that the molecules are connected by hydrogen bonds of the type Osbnd H⋯O and Osbnd H⋯F. In addition, the 2,2'‒bipyridine ligand plays a significant role in the construction of 3-D supramolecular framework via π‒π stacking. FT‒IR and FT‒Raman spectra were used so as to ease the responsibilities of the vibration modes of the title compound. The thermal analysis (TGA) study shows a mass loss evolution as a temperature function. Finally, the optical properties were evaluated by photoluminescence spectroscopy.

  8. Influence of interstitial solutions (H, N) on cerium electronic state in Ce-Fe intermetallic compounds: X-ray Absorption Spectroscopy (XAS) study

    International Nuclear Information System (INIS)

    Chaboy, J.; Marcelli, A.; Bozukov, L.

    1995-03-01

    It is presented an x-ray absorption spectroscopy (XAS) investigation performed at the L-edges of the rare-earth and at the K-edge of iron in the R-Fe intermetallic compounds (La, Ce) 2 Fe 14 BH χ and Ce 2 Fe 17 (H,N) χ , to elucidate the role of the interstitial doping into the electronic and magnetic properties of these systems. Comparison with x-ray circular magnetic dichroism (XCMD) experiments has been carried out to clarify the localization of 4f magnetic moment at the Ce sites upon hydriding. Both XAS and XCMD results evidence the interplay between the structural and magnetic changes, that are associated to the modification of the hybridization between the Fe(3d) and Ce(5d) bands

  9. Magnetic structure of molecular magnet Fe[Fe(CN) 6

    Indian Academy of Sciences (India)

    We have studied the magnetic structure of Fe[Fe(CN)6]·4H2O, prepared by precipitation method, using neutron diffraction technique. Temperature dependent DC magnetization study down to 4.2 K shows that the compound undergoes from a high temperature disordered (paramagnetic) to an ordered magnetic phase ...

  10. Weak ferromagnetic component on the bulk ZnFe{sub 2}O{sub 4} compound

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, C.B.R. [Departamento de Física, Campus prof. Aluísio de Campos, UFS, 49100-000 São Cristóvão, SE (Brazil); Mendonça, E.C. [Departamento de Física, Campus prof. Alberto Carvalho, UFS, 49500-000 Itabaiana, SE (Brazil); Silva, L.S. [Departamento de Física, Campus prof. Aluísio de Campos, UFS, 49100-000 São Cristóvão, SE (Brazil); Folly, W.S.D.; Meneses, C.T. [Departamento de Física, Campus prof. Alberto Carvalho, UFS, 49500-000 Itabaiana, SE (Brazil); Duque, J.G.S., E-mail: gerivaldoduque@gmail.com [Departamento de Física, Campus prof. Alberto Carvalho, UFS, 49500-000 Itabaiana, SE (Brazil)

    2014-01-15

    Magnetization data on the bulk ZnFe{sub 2}O{sub 4} antiferromagnetic compound (T{sub N}≈10 K) obtained via solid state reaction at different synthesis temperatures show one weak ferromagnetic component at room temperature. We have related it with the cationic disorder effect present on spinel structure of our bulk samples which comes from the magnetic interaction between iron ions sit on both octahedral and tetrahedral sites. The magnetization measurements show to all samples a clear peak around 10 K consistent with the antiferromagnetic phase transition. On the other hand, after extracted the paramagnetic component, the hysteresis loops measured at room temperature display one weak ferromagnetic component. Once the T-dependence of magnetization does not fit to a Curie–Weiss law to temperatures well above the magnetic transition we have used a combination of the Curie–Weiss law (paramagnetic spins) and a typical temperature dependence of M{sub 0}, M{sub 0}(T)=M{sub 0}(0)[1−(T/T{sub C}){sup 2}]{sup 0.5} (ordered ferromagnetic spins). We note an increase of the M{sub 0}(0) as function of the synthesis temperature. This reinforce our supposition of a cationic disorder effect driving the system to present two kinds of magnetic interactions between iron ions on A and B sites. - Highlights: • Study of the cationic disorder at bulk ZnFe{sub 2}O{sub 4} compound. • Structural and magnetization characterization. • The observation of two magnetic phases.

  11. Crystal structure of a sodium, zinc and iron(III-based non-stoichiometric phosphate with an alluaudite-like structure: Na1.67Zn1.67Fe1.33(PO43

    Directory of Open Access Journals (Sweden)

    Jamal Khmiyas

    2015-06-01

    Full Text Available The new title compound, disodium dizinc iron(III tris(phosphate, Na1.67Zn1.67Fe1.33(PO43, which belongs to the alluaudite family, has been synthesized by solid-state reactions. In this structure, all atoms are in general positions except for four, which are located on special positions of the C2/c space group. This structure is characterized by cation substitutional disorder at two sites, one situated on the special position 4e (2 and the other on the general position 8f. The 4e site is partially occupied by Na+ [0.332 (3], whereas the 8f site is entirely filled by a mixture of Fe and Zn. The full-occupancy sodium and zinc atoms are located at the Wyckoff positions on the inversion center 4a (-1 and on the twofold rotation axis 4e, respectively. Refinement of the occupancy ratios, bond-valence analysis and the electrical neutrality requirement of the structure lead to the given composition for the title compound. The three-dimensional framework of this structure consists of kinked chains of edge-sharing octahedra stacked parallel to [10-1]. The chains are formed by a succession of trimers based on [ZnO6] octahedra and the mixed-cation FeIII/ZnII [(Fe/ZnO6] octahedra [FeIII:ZnIII ratio 0.668 (3/0.332 (3]. Continuous chains are held together by PO4 phosphate groups, forming polyhedral sheets perpendicular to [010]. The stacked sheets delimit two types of tunnels parallel to the c axis in which the sodium cations are located. Each Na+ cation is coordinated by eight O atoms. The disorder of Na in the tunnel might presage ionic mobility for this material.

  12. Solid-state reactivity explored in situ by synchrotron radiation on single crystals: from SrFeO2.5 to SrFeO3 via electrochemical oxygen intercalation

    International Nuclear Information System (INIS)

    Maity, A; Dutta, R; Penkala, B; Ceretti, M; Letrouit-Lebranchu, A; Perichon, A; Paulus, W; Chernyshov, D; Piovano, A; Bossak, A; Meven, M

    2015-01-01

    In this study we demonstrate the feasibility of following up a chemical reaction by single crystal x-ray (synchrotron) diffraction under operando conditions, carried out in a specially designed electrochemical cell mounted on the BM01A at the European Synchrotron Radiation Facility (ESRF). We investigated in detail the electrochemical oxidation of SrFeO 2.5 to SrFeO 3 on a spherical single crystal of 70 µm diameter by in situ diffraction at an ambient temperature. Complete data sets were obtained by scanning the whole reciprocal space using a 2M Pilatus detector, resulting in 3600 frames with a resolution of 0.1° per data set, each obtained in 18 min. The crystal was mounted in a specially designed electrochemical cell with 1N KOH used as the electrolyte. During the electrochemical oxidation, the reaction proceeds following the phase sequence SrFeO 2.5 /SrFeO 2.75 /SrFeO 2.875 /SrFeO 3 , structurally accompanied by establishing a complex series of long-range oxygen vacancy ordering, which gets instantly organized at ambient temperature. The topotactic reaction pathway is discussed in terms of the evolution of the twin domain structure. The formation of SrFeO 2.875 is accompanied by the formation of diffuse streaks along the [1 0 0]-direction of the perovskite cell, reaching high d-spacings. The diffuse streaks are discussed and are thought to originate from a modified twin structure induced by the SrFeO 2.75 to SrFeO 2.875 transition, and the associated changes in the domain structure, developed during the oxygen intercalation. We equally analysed and discussed in detail the twin structure of all the title compounds. We confirm the ground state of SrFeO 2.5 is able to adopt the Imma space group symmetry, showing stacking faults of the tetrahedral layers along the stacking axis of the brownmillerite unit cell, indicated by the 1D diffuse rods. We showed that in situ single crystal diffraction has huge potential in the study of non-stoichiometric compounds

  13. Solid-state reactivity explored in situ by synchrotron radiation on single crystals: from SrFeO2.5 to SrFeO3 via electrochemical oxygen intercalation

    Science.gov (United States)

    Maity, A.; Dutta, R.; Penkala, B.; Ceretti, M.; Letrouit-Lebranchu, A.; Chernyshov, D.; Perichon, A.; Piovano, A.; Bossak, A.; Meven, M.; Paulus, W.

    2015-12-01

    In this study we demonstrate the feasibility of following up a chemical reaction by single crystal x-ray (synchrotron) diffraction under operando conditions, carried out in a specially designed electrochemical cell mounted on the BM01A at the European Synchrotron Radiation Facility (ESRF). We investigated in detail the electrochemical oxidation of SrFeO2.5 to SrFeO3 on a spherical single crystal of 70 µm diameter by in situ diffraction at an ambient temperature. Complete data sets were obtained by scanning the whole reciprocal space using a 2M Pilatus detector, resulting in 3600 frames with a resolution of 0.1° per data set, each obtained in 18 min. The crystal was mounted in a specially designed electrochemical cell with 1N KOH used as the electrolyte. During the electrochemical oxidation, the reaction proceeds following the phase sequence SrFeO2.5/SrFeO2.75/SrFeO2.875/SrFeO3, structurally accompanied by establishing a complex series of long-range oxygen vacancy ordering, which gets instantly organized at ambient temperature. The topotactic reaction pathway is discussed in terms of the evolution of the twin domain structure. The formation of SrFeO2.875 is accompanied by the formation of diffuse streaks along the [1 0 0]-direction of the perovskite cell, reaching high d-spacings. The diffuse streaks are discussed and are thought to originate from a modified twin structure induced by the SrFeO2.75 to SrFeO2.875 transition, and the associated changes in the domain structure, developed during the oxygen intercalation. We equally analysed and discussed in detail the twin structure of all the title compounds. We confirm the ground state of SrFeO2.5 is able to adopt the Imma space group symmetry, showing stacking faults of the tetrahedral layers along the stacking axis of the brownmillerite unit cell, indicated by the 1D diffuse rods. We showed that in situ single crystal diffraction has huge potential in the study of non-stoichiometric compounds under operando

  14. Band structure of the quaternary Heusler alloys ScMnFeSn and ScFeCoAl

    Science.gov (United States)

    Shanthi, N.; Teja, Y. N.; Shaji, Shephine M.; Hosamani, Shashikala; Divya, H. S.

    2018-04-01

    In our quest for materials with specific applications, a theoretical study plays an important role in predicting the properties of compounds. Heusler alloys or compounds are the most studied in this context. More recently, a lot of quaternary Heusler compounds are investigated for potential applications in fields like Spintronics. We report here our preliminary study of the alloys ScMnFeSn and ScFeCoAl, using the ab-initio linear muffin-tin orbital method within the atomic sphere approximation (LMTO-ASA). The alloy ScMnFeSn shows perfect half-metallicity, namely, one of the spins shows a metallic behaviour and the other spin shows semi-conducting behaviour. Such materials find application in devices such as the spin-transfer torque random access memory (STT-MRAM). In addition, the alloy ScMnFeSn is found to have an integral magnetic moment of 4 µB, as predicted by the Slater-Pauling rule. The alloy ScFeCoAl does not show half-metallicity.

  15. Structure and magnetism of new rare-earth-free intermetallic compounds: Fe3+xCo3−xTi2 (0 ≤ x ≤ 3

    Directory of Open Access Journals (Sweden)

    Balamurugan Balasubramanian

    2016-11-01

    Full Text Available We report the fabrication of a set of new rare-earth-free magnetic compounds, which form the Fe3Co3Ti2-type hexagonal structure with P-6m2 symmetry. Neutron powder diffraction shows a significant Fe/Co anti-site mixing in the Fe3Co3Ti2 structure, which has a strong effect on the magnetocrystalline anisotropy as revealed by first-principle calculations. Increasing substitution of Fe atoms for Co in the Fe3Co3Ti2 lattice leads to the formation of Fe4Co2Ti2, Fe5CoTi, and Fe6Ti2 with significantly improved permanent-magnet properties. A high magnetic anisotropy (13.0 Mergs/cm3 and saturation magnetic polarization (11.4 kG are achieved at 10 K by altering the atomic arrangements and decreasing Fe/Co occupancy disorder.

  16. An overview of the Fe-chalcogenide superconductors

    International Nuclear Information System (INIS)

    Wu, M K; Wen, Y C; Chen, T K; Chang, C C; Wu, P M; Wang, M J; Lin, P H; Lee, W C

    2015-01-01

    This review intends to summarize recent advancements in FeSe and related systems. The FeSe and related superconductors are currently receiving considerable attention for the high critical temperature (T C ) observed and for many similar features to the high T C cuprate superconductors. These similarities suggest that understanding the FeSe-based compounds could potentially help our understanding of the cuprates. We begin the review by presenting common features observed in the FeSe- and FeAs-based systems. Then we discuss the importance of careful control of the material preparation allowing for a systematic structure characterization. With this control, numerous rich phases have been observed. Importantly, we suggest that the Fe-vacancy ordered phases found in the FeSe-based compounds, which are non-superconducting magnetic Mott insulators, are the parent compounds of the superconductors. Superconductivity can emerge from the parent phases by disordering the Fe vacancy order, often by a simple annealing treatment. Then we review physical properties of the Fe chalcogenides, specifically the optical properties and angle-resolved photoemission spectroscopy (ARPES) results. From the literature, strong evidence points to the existence of orbital modification accompanied by a gap-opening, prior to the structural phase transition, which is closely related to the occurrence of superconductivity. Furthermore, strong lattice to spin coupling are important for the occurrence of superconductivity in FeSe. Therefore, it is believed that the iron selenides and related compounds will provide essential information to understand the origin of superconductivity in the iron-based superconductors, and possibly the superconducting cuprates. (topical review)

  17. The effect of a fourth element (Co, Cu, Fe, Pd) on the standard enthalpy of formation of the Heusler compound Ni{sub 2}MnSn

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Ming, E-mail: myin1@hawk.iit.edu; Nash, Philip

    2016-05-15

    The standard enthalpies of formation of quaternary Heusler compounds (X, Ni){sub 2}MnSn (X = Co, Cu, Fe, Pd) were investigated experimentally using high temperature direct reaction calorimetry. Lattice parameters of these compounds were determined using X-ray diffraction analysis. Microstructures were identified using scanning electron microscopy and energy dispersive spectroscopy. The effect of an additional X element on the standard enthalpy of formation of the Heusler compound Ni{sub 2}MnSn is discussed. - Highlights: • Enthalpies of formation of (X,Ni){sub 2}YZ (X = Co, Cu, Fe, Pd) were measured by drop calorimeters. • Magnetic contribution to enthalpy of formation plays an important role. • Introducing a fourth element could stabilize an unstable Heusler structure. • Lattice parameters do not necessarily obey the Vegard's law. • It is possible to tailor properties of Heusler compounds with enough background information.

  18. Experimental and thermodynamic assessments of substitutions in the AlFeSi, FeMnSi, FeSiZr and AlCaFeSi systems (65 wt % Si) - solidification simulation

    International Nuclear Information System (INIS)

    Gueneau, C.; Ansara, I.

    1994-01-01

    The substitutions of Al Si, Fe Mn and Fe Zr in some intermetallic compounds of the Al-Fe-Si, Fe-Mn-Si and Fe-Si-Zr systems are modelled in the Si-rich corner using a two sublattice model. The solidification paths of the studied alloys are determined at equilibrium. The ascalculated phase volume fractions of the alloys are compared to the experimental ones. Finally, a solidification simulation using the Gulliver-Scheil's model is performed in order to explain the formation of some precipitates experimentally observed. (authors). 14 figs., 19 refs

  19. Deep desulfurization of diesel oil oxidized by Fe (VI) systems

    Energy Technology Data Exchange (ETDEWEB)

    Shuzhi Liu; Baohui Wang; Baochen Cui; Lanlan Sun [Daqing Petroleum Institute, Daqing (China). College of Chemistry and Chemical Engineering

    2008-03-15

    Fe (VI) compound, such as K{sub 2}FeO{sub 4}, is a powerful oxidizing agent. Its oxidative potential is higher than KMnO{sub 4}, O{sub 3} and Cl{sub 2}. Oxidation activity of Fe (VI) compounds can be adjusted by modifying their structure and pH value of media. The reduction of Fe (VI), differing from Cr and Mn, results in a relatively non-toxic by-product Fe (III) compounds, which suggests that Fe (VI) compound is an environmentally friendly oxidant. Oxidation of model sulfur compound and diesel oil by K{sub 2}FeO{sub 4} in water-phase, in organic acid and in the presence of phase-transfer catalysts is investigated, respectively. The results show that the activity of oxidation of benzothiophene (BT) and dibenzothiophene (DBT) is low in water-phase, even adding phase-transfer catalyst to the system, because K{sub 2}FeO{sub 4} reacts rapidly with water to form brown Fe(OH){sub 3} to lose ability of oxidation of organic sulfur compounds. The activity of oxidation of the BT and DBT increases markedly in acetic acid. Moreover, the addition of the solid catalyst to the acetic acid medium promotes very remarkably oxidation of organic sulfur compounds. Conversions of the DBT and BT are 98.4% and 70.1%, respectively, under the condition of room temperature, atmospheric pressure, acetic acid/oil (v/v) = 1.0, K{sub 2}FeO{sub 4}/S (mol/mol) = 1.0 and catalyst/K{sub 2}FeO{sub 4} (mol/mol) = 1.0. Under the same condition, diesel oil is oxidized, followed by furfural extraction, the results display sulfur removal rate is 96.7% and sulfur content in diesel oil reduces from 457 ppm to 15.1 ppm. 11 refs., 9 figs., 5 tabs.

  20. Calculation of the magnetic properties of pseudo-ternary R2M14B intermetallic compounds (R = rare earth, M = Fe, Co

    Directory of Open Access Journals (Sweden)

    Gabriel Gómez Eslava

    2016-06-01

    Full Text Available The extrinsic properties of NdFeB-based magnets can be tuned through partial substitution of Nd by another rare-earth element and Fe by Co, as such substitution leads to a modification in the intrinsic properties of the main phase. Optimisation of a magnet's composition through trial and error is time consuming and not straightforward, since the interplay existing between magnetocrystalline anisotropy and coercivity is not completely understood. In this paper we present a model to calculate the intrinsic magnetic properties of pseudo-ternary Nd2Fe14B-based compounds. As concrete examples, which are relevant for the optimisation of NdFeB-based high-performance magnets used in (hybrid electric vehicles and wind turbines, we consider partial substitution of Nd by Dy or Tb, and Fe by Co.

  1. Synthesis, structure and chemical bonding of CaFe2−xRhxSi2 (x=0, 1.32, and 2) and SrCo2Si2

    International Nuclear Information System (INIS)

    Hlukhyy, Viktor; Hoffmann, Andrea V.; Fässler, Thomas F.

    2013-01-01

    The finding of superconductivity in Ba 0.6 K 0.4 Fe 2 As 2 put the attention on the investigation of compounds that crystallize with ThCr 2 Si 2 structure type such as AT 2 X 2 (A=alkali/alkaline earth/rare earth element; T=transition metal and X=element of the 13–15th group). In this context the silicides CaFe 2 Si 2 , CaFe 0.68(6) Rh 1.32(6) Si 2 , CaRh 2 Si 2 and SrCo 2 Si 2 have been synthesized by reaction of the elements under an argon atmosphere. Single crystals were obtained by special heat treatment in welded niobium/tantalum ampoules. The compounds were investigated by means of powder and single crystal X-ray diffraction. All compounds crystallize in the ThCr 2 Si 2 -type structure with space group I4/mmm (No. 139): a=3.939(1) Å, c=10.185(1) Å, R 1 =0.045, 85 F 2 values, 8 variable parameters for CaFe 2 Si 2 ; a=4.0590(2) Å, c=9.9390(8) Å, R 1 =0.030, 90 F 2 values, 10 variable parameters for CaFe 0.68(6) Rh 1.32(6) Si 2 ; a=4.0695(1) Å, c=9.9841(3) Å, R 1 =0.031, 114 F 2 values, 9 variable parameters for CaRh 2 Si 2 ; and a=3.974(1) Å, c=10.395(1) Å, R 1 =0.036, 95 F 2 values, 8 variable parameters for SrCo 2 Si 2 . The structure of SrCo 2 Si 2 contains isolated [Co 2 Si 2 ] 2− 2D-layers in the ab-plane whereas in CaFe 2−x Rh x Si 2 the [T 2 Si 2 ] layers (T=Fe and Rh) are interconnected along the c-axis via Si3Si bonds resulting in a three-dimentional (3D) [T 2 Si 2 ] 2− polyanions and therefore belong to the so-called collapsed form of the ThCr 2 Si 2 -type structure. The SrCo 2 Si 2 and CaRh 2 Si 2 are isoelectronic to the parent 122 iron–pnictide superconductors AeFe 2 As 2 (Ae=alkaline earth elements), whereas CaFe 2 Si 2 is a full substituted variant (As/Si) of CaFe 2 As 2 . The crystal chemistry and chemical bonding in the title compounds are discussed in terms of LMTO band structure calculations and a topological analysis using the Electron Localization Function (ELF). - Graphical abstract: The SrCo 2 Si 2 and CaFe 2−x Rh x Si

  2. Theoretical study of thermopower behavior of LaFeO3 compound in high temperature region

    Science.gov (United States)

    Singh, Saurabh; Shastri, Shivprasad S.; Pandey, Sudhir K.

    2018-04-01

    The electronic structure and thermopower (α) behavior of LaFeO3 compound were investigated by combining the ab-initio electronic structures and Boltzmann transport calculations. LSDA plus Hubbard U (U = 5 eV) calculation on G-type anti-ferromagnetic (AFM) configuration gives an energy gap of ˜2 eV, which is very close to the experimentally reported energy gap. The calculated values of effective mass of holes (mh*) in valance band (VB) are found ˜4 times that of the effective mass of electrons (me*) in conduction band (CB). The large effective masses of holes are responsible for the large and positive thermopower exhibited by this compound. The calculated values of α using BoltzTraP code are found to be large and positive in the 300-1200 K temperature range, which is in agreement with the experimentally reported data.

  3. Hydrogen storage in Mg-Ni-Fe compounds prepared by melt spinning and ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Palade, P. [Settore Materiali, Dipartimento di Ingegneria Meccanica, Universita di Padova, via Marzolo 9, 35131 Padova (Italy); National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania); Sartori, S. [Settore Materiali, Dipartimento di Ingegneria Meccanica, Universita di Padova, via Marzolo 9, 35131 Padova (Italy); Maddalena, A. [Settore Materiali, Dipartimento di Ingegneria Meccanica, Universita di Padova, via Marzolo 9, 35131 Padova (Italy); Principi, G. [Settore Materiali, Dipartimento di Ingegneria Meccanica, Universita di Padova, via Marzolo 9, 35131 Padova (Italy)]. E-mail: giovanni.principi@unipd.it; Lo Russo, S. [Dipartimento di Fisica, Universita di Padova, Via Marzolo 8, 35131 Padova (Italy); Lazarescu, M. [National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania); Schinteie, G. [National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania); Kuncser, V. [National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania); Filoti, G. [National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania)

    2006-05-18

    Magnesium-rich Mg-Ni-Fe intermetallic compounds have been prepared by two different routes: (a) short time ball milling of ribbons obtained by melt spinning; (b) long time ball milling of a mixture of MgH{sub 2}, Ni and Fe powders. The first type of samples displays an hydrogen desorption kinetics better than the second one. Pressure composition isotherm measurements exhibit for both type of samples two plateaux, the lower and wider corresponding to the MgH{sub 2} phase and the upper and shorter corresponding to the Mg{sub 2}NiH{sub 4} phase. The presence of the two types of hydrides is confirmed by X-ray diffraction analysis. Moessbauer spectroscopy shows that in melt spun and subsequently milled samples iron is mainly in a disordered structure and segregates after hydrogenation, while in directly milled powders remains mainly unalloyed. After multiple hydrogen absorption/desorption cycles the main part of iron is in metallic state in samples of both types, those of first type preserving better hydrogen desorption kinetics.

  4. Intensive structural investigation of R{sub 2}Fe{sub 17-x}M{sub x} intermetallic compounds using high resolution powder neutron diffractometer

    Energy Technology Data Exchange (ETDEWEB)

    Mujamilah,; Ridwan, [Materials Science Research Center, National Atomic Energy Agency of Indonesia, Jakarta (Indonesia)

    1998-10-01

    The crystallographic and magnetic structure of R{sub 2}Fe{sub 17-x}M{sub x} intermetallic compounds system were refined by Rietveld analyses of the high resolution neutron powder diffraction data. The analyses results show that the substituent atoms were not distributed randomly over the Fe sites, but preferentially occupied some Fe sites. More further, it was also found that the substituent atoms which atomic radius smaller than Fe tend to avoid the 6c site at low concentration while the larger substituent atom tend to replace the Fe atom at this 6c site corresponding to their concentration. From these crystallographic data, it was suggested that the change of magnetic ordering temperature Tc, is not mainly determined by the change of short bond distance between this `dumb-bell` atoms, but it was also influenced by the nearest coordinated atoms to this site. (author)

  5. Synthesis, thermodynamic and transport properties of the compounds Sr3FeMO7-δ(M = Fe, Ni) in the temperature range of 400≤T≤1000oC

    International Nuclear Information System (INIS)

    Mogni, L; Prado, E; Caneiro, A

    2004-01-01

    The synthesis is presented for the mixed conductors Sr 3 FeMO 7-δ (M = Fe, Ni) belonging to the Ruddlesden Popper series A n+1 B n O3 n+1 with n = 2 using the acetates method. The samples were characterized using X-ray diffraction techniques, scanning electron microscopy and EDS. The variation of the chemical potential of oxygen was determined with the oxygen content of these compounds (7-δ) in a wide range of partial oxygen pressure 10 -5 ≤pO2≤ 1 atm and temperatures (673-1273 K). The electrical conductivity as a function of the temperature and the pO2 were measured by the four points method. Based on an analysis of the test data the effect of the cationic substitution of Fe by Ni on the thermodynamic, structural properties and on the structure of defects in the temperature range of interest for the electrochemical devices is discussed (WC)

  6. Magnetic and electrical properties of In doped FeCr{sub 2}S{sub 4} compound

    Energy Technology Data Exchange (ETDEWEB)

    Sagredo, V. [Lab. de Magnetismo, Facultad de Ciencias, Universidad de los Andes, Merida, 5101 (Venezuela)], E-mail: sagredo@ula.ve; Davila, Y. [Lab. de Magnetismo, Facultad de Ciencias, Universidad de los Andes, Merida, 5101 (Venezuela); Goya, G.F. [Instituto Universitario de Investigacion en Nanociencia de Aragon, Zaragoza (Spain)

    2008-07-15

    Single crystals of FeIn{sub 1-x}Cr{sub 2x}S{sub 4} compounds have been grown by using the chemical transport method. DC magnetization measurements on single crystals for 0.6{<=}x{<=}1.0 revealed a reentrant behavior below T{sub sg}=120-170 K depending on the Cr concentration sample. The transition temperature T{sub c} increases as the indium concentration increases. The electrical resistivity measurements on polycrystalline materials above the Curie temperature revealed that the conduction behavior could be described as magnetic-polaron transport.

  7. Vibrational properties of stannite and kesterite type compounds: Raman scattering analysis of Cu{sub 2}(Fe,Zn)SnS{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Fontane, X.; Izquierdo-Roca, V.; Saucedo, E. [IREC: Catalonia Institute for Energy Research, C. Jardins de les Dones de Negre 1, Sant Adria del Besos, Barcelona 08930 (Spain); Schorr, S. [Free University Berlin, Institute of Geological Sciences, Malteserstr. 74-100, Berlin (Germany); Yukhymchuk, V.O.; Valakh, M.Ya. [V.E. Lahskaryov Institute of Semiconductor Physics, National Academy of Sciences, Prospekt Nauki 41, Kiev 03028 (Ukraine); Perez-Rodriguez, A., E-mail: aperezr@irec.cat [IREC: Catalonia Institute for Energy Research, C. Jardins de les Dones de Negre 1, Sant Adria del Besos, Barcelona 08930 (Spain); IN2UB, Departament d' Electronica, Universitat de Barcelona, C. Marti i Franques 1, 08028 Barcelona (Spain); Morante, J.R. [IREC: Catalonia Institute for Energy Research, C. Jardins de les Dones de Negre 1, Sant Adria del Besos, Barcelona 08930 (Spain); IN2UB, Departament d' Electronica, Universitat de Barcelona, C. Marti i Franques 1, 08028 Barcelona (Spain)

    2012-10-25

    Highlights: Black-Right-Pointing-Pointer Analysis of main and weaker Raman peaks from Cu{sub 2}FeZnS{sub 4} and Cu{sub 2}ZnSnS{sub 4} compounds. Black-Right-Pointing-Pointer Identification of a cation disorder induced Raman peak in Cu{sub 2}ZnSnS{sub 4}. Black-Right-Pointing-Pointer Analysis of spectral features of main Raman peaks from Cu{sub 2}(Fe,Zn)SnS{sub 4}. - Abstract: This work reports the analysis of the vibrational properties of stannite-kesterite Cu{sub 2}(Fe,Zn)SnS{sub 4} compounds that has been performed by Raman scattering measurements. The detailed analysis of the experimental spectra has allowed determining the frequency and symmetry assignment of the main and weaker peaks from both stannite Cu{sub 2}FeSnS{sub 4} (CFTS) and kesterite Cu{sub 2}ZnSnS{sub 4} (CZTS) phases. The measurements performed in the kesterite CZTS samples have also revealed the presence of local inhomogeneities that are characterised by an additional peak in the spectra at about 331 cm{sup -1}. This peak has been related to the presence in these local regions of a high degree of disorder in the cation sublattice, in agreement with previous neutron diffraction analysis in similar samples. Finally, the spectra from the solid solution alloys show a one-mode behaviour of the main A/A{sub 1} peak with the chemical composition.

  8. Nearly constant magnetic entropy change involving two closely spaced transitions in the compound LaFe11.375Al1.625

    International Nuclear Information System (INIS)

    Hu, F X; Qian, X L; Wang, G J; Wang, J; Sun, J R; Zhang, X X; Cheng, Z H; Shen, B G

    2003-01-01

    A large change in the magnetic entropy, |ΔS|, was observed in the Fe-based NaZn 13 -type compound LaFe 11.375 Al 1.625 , which was nearly temperature independent over a wide temperature range (an about 70 K span from ∼ 140 to 210 K). This behaviour of the magnetic entropy change is associated with two closely spaced magnetic transitions. X-ray diffraction investigation at different temperatures indicates that the crystal structure remains cubic, of NaZn 13 type, when the magnetic state changes with temperature, but the cell parameter changes dramatically at the first-order transition point

  9. Preparation and Eh-pH diagrams of Fe(II)-Fe(III) green rust compounds; hyperfine interaction characteristics and stoichiometry of hydroxy-chloride, -sulphate and -carbonate

    International Nuclear Information System (INIS)

    Genin, J.-M.R.; Refait, Ph.; Simon, L.; Drissi, S.H.

    1998-01-01

    Fe(II)-Fe(III) hydroxy-chloride, -sulphate and -carbonate were prepared by oxidation of a ferrous hydroxide precipitate in anion-containing aqueous solutions. The compounds are characterized by monitoring the redox potential E h and the pH of stochiometric suspension vs time with the appropriate concentration ratios. X-ray diffraction allows us to characterize the crystal structure by distinguishing 'green rust one' (GR1) from 'green rust two' (GR2). Since green rusts (GRs) are of a pyroaurite-sjoegrenite-like structure, i.e., consisting of intercalated foreign anions and water molecules in the interlayers between the brucite-like layers of Fe(OH) 2 , their chemical formulae can be determined from the Moessbauer spectra. Three quadrupole doublets are observed: D 1 and D 2 correspond to a ferrous state with isomershift IS of about 1.27 mm s -1 and quadrupole splittings QS of about 2.85 and 2.60 mm s -1 , respectively, whereas D 3 corresponds to a ferric state with IS and QS of about 0.4 mm s -1 . The hyperfine parameters of these doublets are similar from one green rust to another but their intensity ratios vary considerably. Finally, E h and pH equilibrium diagrams of the Fe species in the presence of chloride, sulphate and carbonate anions contained within the water solution are drawn and the thermodynamic conditions of existence and degrees of oxidation of green rusts are discussed

  10. Magnetic characteristics of M2FeV3O11 (M = Mg, Zn, Pb, Co, Ni) compounds

    Science.gov (United States)

    Groń, T.; Blonska-Tabero, A.; Filipek, E.; Stokłosa, Z.; Duda, H.; Sawicki, B.

    2018-02-01

    The unusual physical characteristics of the multicomponent oxide systems renewed the interest as the potential cathode materials in high-energy cells. Since the earlier magnetic characteristics were not entirely conclusive, we report the results of dc magnetic measurements including higher harmonics of ac magnetic susceptibility of the M2FeV3O11 (M = Mg, Zn, Pb, Co, Ni) compounds. Ferrimagnetic long-range and antiferromagnetic short-range interactions for all compounds under study at low temperatures as well as superparamagnetic-like behavior with the blocking temperature of 29 K and the freezing parameter of 0.013 were observed. These effects are discussed within the framework of superexchange and double exchange magnetic interactions as well as the mixed valence band of iron ions.

  11. Ligand-field symmetry effects in Fe(ii) polypyridyl compounds probed by transient X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hana; Strader, Matthew L.; Hong, Kiryong; Jamula, Lindsey; Gullikson, Eric M.; Kim, Tae Kyu; de Groot, Frank M. F.; McCusker, James K.; Schoenlein, Robert W.; Huse, Nils

    2012-01-01

    Ultrafast excited-state evolution in polypyridyl FeII complexes are of fundamental interest for understanding the origins of the sub-ps spin-state changes that occur upon photoexcitation of this class of compounds as well as for the potential impact such ultrafast dynamics have on incorporation of these compounds in solar energy conversion schemes or switchable optical storage technologies. We have demonstrated that ground-state and, more importantly, ultrafast time-resolved x-ray absorption methods can offer unique insights into the interplay between electronic and geometric structure that underpin the photo-induced dynamics of this class of compounds. The present contribution examines in greater detail how the symmetry of the ligand field surrounding the metal ion can be probed using these x-ray techniques. In particular, we show that steady-state K-edge spectroscopy of the nearest-neighbour nitrogen atoms reveals the characteristic chemical environment of the respective ligands and suggests an interesting target for future charge-transfer femtosecond and attosecond spectroscopy in the x-ray water window.

  12. Tetragonal To Collapsed Tetragonal Phase Transition In BaFe2As2 and CaFe2As2

    International Nuclear Information System (INIS)

    Mittal, R.; Mishra, S. K.; Chaplot, S. L.; Ovsyannikov, S. V.; Trots, D. M.; Dubrovinsky, L.; Greenberg, E.; Su, Y.; Brueckel, Th.; Matsuishi, S.; Hosono, H.; Garbarino, G.

    2010-01-01

    Superconductivity in MFe 2 As 2 (M = Ba, Ca) compounds appears either at a critical doping level at ambient pressure or in the parent compound itself by application of pressure above a critical value. We report high pressure powder x-ray diffractions studies for these compounds at 300 K up to about 56 GPa using membrane diamond anvil cells. The measurements for BaFe 2 As 2 show a new tetragonal to collapsed tetragonal phase transition at about 22 GPa that remains stable upto 56 GPa. CaFe 2 As 2 is already known to transform to collapsed phase at 1.7 GPa at 300 K. Our measurements on CaFe 2 As 2 do not show any post collapsed phase transition on increase of pressure 50 GPa at 300 K. It is important to note that the transition in both compounds occurs when they are compressed to almost the same value of the unit cell volume and attain similar c t /a t ratios. We present a detailed analysis of the pressure dependence and structure phase transitions as well as equation of state in these important FeAs compounds that should be useful in the context of possible superconductivity in the collapsed phase.

  13. Hydrothermal synthesis of layered iron-chalcogenide superconductors and related compounds

    International Nuclear Information System (INIS)

    Pachmayr, Ursula Elisabeth

    2017-01-01

    This thesis provides a new preparative approach to iron-chalcogenide based superconductors. The hydrothermal synthesis of anti-PbO type FeSe, which can be seen as basis structure of the compounds of interest was successfully developed. Along with this, some insights regarding the influence of synthesis parameters were gained featuring a basis for further hydrothermal syntheses of new iron-chalcogenide compounds. The potential of this method, primarily the extension of the so far limited accessibility of iron-chalcogenide based superconductors by solid-state sythesis, was revealed within the present work. The solid-solution FeSe_1_-_xS_x was prepared for the whole substitution range, whereas solid-state synthesis exhibits a solubility limit at x = 0.3. Furthermore, the new compounds [(Li_0_._8Fe_0_._2)OH]FeX (X = Se, S) were synthesized which are exclusively accessible via hydrothermal method. The compounds, where layers of (Li_0_._8Fe_0_._2)OH alternate with FeX layers, feature exceptional physical properties, notably a coexistence of superconductivity and ferromagnetism. They were intensively studied within this work. By combination of solid-state and hydrothermal ion-exchange synthesis even large crystals necessary for subsequent physical measurements are accessible. Apart from these layered iron-chalcogenide superconductors, further compounds which likewise exhibit building blocks of edge-sharing FeSe_4 tetrahedra were found via this synthesis method. The iron selenides A_2Fe_4Se_6 (A = K, Rb, Cs) consist of double chains of [Fe_2Se_3]"1"-, whereas a new compound Na_6(H_2O)_1_8Fe_4Se_8 exhibits [Fe_4Se_8]"6"- 'stella quadrangula' clusters. This structural diversity as well as the associated physical properties of the compounds demonstrates the numerous capabilities of hydrothermal synthesis in the field of iron-chalcogenide compounds. In particular with regard to iron-chalcogenide based superconductors this synthesis strategy is encouraging. It seems probable

  14. Hydrothermal synthesis of layered iron-chalcogenide superconductors and related compounds

    Energy Technology Data Exchange (ETDEWEB)

    Pachmayr, Ursula Elisabeth

    2017-04-06

    This thesis provides a new preparative approach to iron-chalcogenide based superconductors. The hydrothermal synthesis of anti-PbO type FeSe, which can be seen as basis structure of the compounds of interest was successfully developed. Along with this, some insights regarding the influence of synthesis parameters were gained featuring a basis for further hydrothermal syntheses of new iron-chalcogenide compounds. The potential of this method, primarily the extension of the so far limited accessibility of iron-chalcogenide based superconductors by solid-state sythesis, was revealed within the present work. The solid-solution FeSe{sub 1-x}S{sub x} was prepared for the whole substitution range, whereas solid-state synthesis exhibits a solubility limit at x = 0.3. Furthermore, the new compounds [(Li{sub 0.8}Fe{sub 0.2})OH]FeX (X = Se, S) were synthesized which are exclusively accessible via hydrothermal method. The compounds, where layers of (Li{sub 0.8}Fe{sub 0.2})OH alternate with FeX layers, feature exceptional physical properties, notably a coexistence of superconductivity and ferromagnetism. They were intensively studied within this work. By combination of solid-state and hydrothermal ion-exchange synthesis even large crystals necessary for subsequent physical measurements are accessible. Apart from these layered iron-chalcogenide superconductors, further compounds which likewise exhibit building blocks of edge-sharing FeSe{sub 4} tetrahedra were found via this synthesis method. The iron selenides A{sub 2}Fe{sub 4}Se{sub 6} (A = K, Rb, Cs) consist of double chains of [Fe{sub 2}Se{sub 3}]{sup 1-}, whereas a new compound Na{sub 6}(H{sub 2}O){sub 18}Fe{sub 4}Se{sub 8} exhibits [Fe{sub 4}Se{sub 8}]{sup 6-} 'stella quadrangula' clusters. This structural diversity as well as the associated physical properties of the compounds demonstrates the numerous capabilities of hydrothermal synthesis in the field of iron-chalcogenide compounds. In particular with regard

  15. Second order magnetic phase transition and scaling analysis in iron doped manganite La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Fe{sub x}O{sub 3} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ginting, Dianta [Department of Applied Physics and Institute of Natural Sciences, Kyung Hee University, Yong-in 446-701 (Korea, Republic of); Nanto, Dwi [Physics Education, Syarif Hidayatullah State Islamic University, Jakarta 15412 (Indonesia); Denny, Yus Rama [Department of Electrical Engineering, University of Sultan Ageng Tirtayasa, Banten 42435 (Indonesia); Tarigan, Kontan [Department of Mechanical Engineering, Mercu Buana University, Jakarta-Barat, Jakarta 11650 (Indonesia); Hadi, Syamsul [Department of Mechanical Engineering, State Polytechnic of Malang, East Java 65100 (Indonesia); Ihsan, Mohammad [PSTBM-BATAN, Kawasan Puspiptek Serpong, Tangerang Selatan, Banten 15314 (Indonesia); Institute of Electronic Materials, University of Wollongong, Wollongong NSW 2522 (Australia); Rhyee, Jong-Soo, E-mail: jsrhyee@khu.ac.kr [Department of Applied Physics and Institute of Natural Sciences, Kyung Hee University, Yong-in 446-701 (Korea, Republic of)

    2015-12-01

    We investigated magnetic properties of La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Fe{sub x}O{sub 3} (x=0.09 and 0.11) compounds in terms of isothermal magnetization analysis and scaling behavior with various critical exponents. From the Landau theory of magnetic phase transition, we found that the paramagnetic to ferromagnetic phase transition in La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Fe{sub x}O{sub 3} (x=0.09 and 0.11) compounds is the type of second order magnetic transition (SOMT), which contrary to the first order magnetic transition (FOMT) for low Fe-doped compounds (x<0.09) in previous reports. When we investigate the critical behavior of the compounds near T=T{sub c} by the modified Arrott plot, Kouvel–Fisher plots, and critical isothermal analysis, the estimated critical exponents β, γ, and δ are in between the theoretically predicted values for three-dimensional Heisenberg and mean-field interaction models. It is noteworthy that the scaling relations are obeyed in terms of renormalization magnetization m=ε{sup −β}M(H,ε) and renormalized field h=|ε|{sup β+γ}H. Temperature-dependent effective exponents β{sub eff} and γ{sub eff} correspond to the ones of disordered ferromagnets. It is shown that the magnetic state of the compounds is not fully described by the conventional localized-spin interaction model because the ferromagnetic interaction has itinerant character by increasing Fe-doping concentration. - Highlights: • The ferromagnetic phase transition is of second order in La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Fe{sub x}O{sub 3}. • The critical exponents are in between the 3D Heisenberg and mean-field models. • The ferromagnetic interaction becomes more itinerant by Fe-doping.

  16. Hyperfine properties of La(V{sub 1−x}Fe{sub x})O{sub 3} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Tupan, L. F. S.; Ivashita, F. F.; Barco, R. [Universidade Estadual de Maringá (Brazil); Hallouche, B. [Universidade de Santa Cruz do Sul (Brazil); Paesano, A., E-mail: paesano@wnet.com.br [Universidade Estadual de Maringá (Brazil)

    2017-11-15

    LaV{sub 1−x}Fe{sub x}O{sub 3} perovskites were synthesized in the vanadium-rich concentration range (i.e., x < 0.5) and characterized structurally and for the hyperfine properties of the iron nuclear probe. The aim of this investigation was to better understand the physical transformations that take place in the undoped compound (LaVO{sub 3}) at low temperatures. For that, X-ray diffraction analysis and, more extensively, {sup 57}Fe Mössbauer spectroscopy were applied. The results revealed that the LaV{sub 1}-xFexO{sub 3} vanadium-rich perovskites are orthorhombic at RT, and their lattice parameters decrease with increasing vanadium concentration. Lowering the temperature, the system becomes magnetic, with the iron moment freezing progressively. The presence of two magnetic subspectral components obtained at the lowest measurement temperatures suggests that the vanadium-rich samples, including LaVO{sub 3}, undergo a phase transition from an orthorhombic to a monoclinic structure at low temperatures.

  17. Anomalous magnetic aftereffect in Nd3(Fe,T)29 (T = Ti or Re) intermetallic compounds

    International Nuclear Information System (INIS)

    Collocott, S.J.; Dunlop, J.B.; Gwan, P.B.

    1999-01-01

    Full text: The intermetallic compounds Nd 3 (Fe,Ti) 29 and Nd 3 (Fe,Re) 29 order ferromagnetically with Curie Temperatures, T c , of 430 and 370 K respectively. They have a monoclinic crystal structure, space group A2/m (Nd 3 (Fe,Ti) 29 type) with two rare earth sites and eleven Fe(T) sites, which is an intermediate structure between the rhombohedral Th 2 Zn 17 and tetragonal ThMn 12 structures, and is closely related to hexagonal CaCu 5 . Ferromagnetic materials, depending on their magnetic prehistory, may exhibit a time dependent magnetisation. The term 'magnetic aftereffect' is used to describe this behaviour, which may fall into three categories: 1. Reversible or diffusion aftereffect which is associated with the diffusion of impurity atoms or holes within the ferromagnetic lattice. 2. The irreversible or fluctuation aftereffect, which results in a logarithmic time dependence of magnetisation, J(t)=J(0)+Sln(t+t 0 ), where S is the magnetic viscosity and t 0 a parameter to establish the origin of the time scale measurements. 3. Quantum tunnelling of magnetisation which is observed at very low temperatures. A range of magnetic aftereffects have been observed in both Nd 3 (Fe,Ti) 29 and Nd 3 (Fe,Re) 29 . Of particular interest is the case where the material is fully saturated by application of a field in the positive direction, the applied field is then reversed to trace out part of the major demagnetisation curve into the third quadrant, and thence along a recoil curve, such that in zero applied field the magnetisation is zero (H=0, J=0). (This corresponds to dc field magnetisation.) This magnetic prehistory results in two interesting effects; spontaneous remagnetisation e.g. remagnetisation without application of an external field, and thermal remagnetisation e.g. an increase in magnetisation as the temperature is increased. Additionally, the behaviour of the magnetic viscosity has been explored on the major demagnetisation curve as a function of temperature

  18. Phase equilibrium of the Gd-Fe-Co system at 873 K

    International Nuclear Information System (INIS)

    Huang Jinli; Zhong Haichang; Xia Xiuwen; He Wei; Zhu Jinming; Deng Jianqiu; Zhuang Yinghong

    2009-01-01

    Phase equilibrium of the ternary Gd-Fe-Co system at 873 K was investigated by using X-ray diffraction technique, electron probe microanalysis, metallographic analysis and differential thermal analysis. The 873 K isothermal section of the phase diagram of the Gd-Fe-Co ternary system consists of 11 single-phase regions, 16 two-phase regions and 6 three-phase regions. Three pairs of corresponding compounds of Gd-Co and Gd-Fe, i.e., Gd 2 Co 17 and Gd 2 Fe 17 , GdCo 3 and GdFe 3 , GdCo 2 and GdFe 2 , form a continuous series of solid solution. The compound Gd 2 Co 7-x Fe x was found to have a broad solubility range from 0 to 31 at.% Fe. The maximum solubility of Co in Gd 6 Fe 23 is about 7 at.% Co. At 873 K, the maximum solubilities of Fe in Gd 3 Co and Gd 4 Co 3 are about 3 and 1 at.% Fe, respectively. No ternary compound was found in all ternary alloy samples

  19. Electrochemical alkaline Fe(VI) water purification and remediation.

    Science.gov (United States)

    Licht, Stuart; Yu, Xingwen

    2005-10-15

    Fe(VI) is an unusual and strongly oxidizing form of iron, which provides a potentially less hazardous water-purifying agent than chlorine. A novel on-line electrochemical Fe(VI) water purification methodology is introduced. Fe(VI) addition had been a barrier to its effective use in water remediation, because solid Fe(VI) salts require complex (costly) syntheses steps and solutions of Fe(VI) decompose. Online electrochemical Fe(VI) water purification avoids these limitations, in which Fe(VI) is directly prepared in solution from an iron anode as the FeO42- ion, and is added to the contaminant stream. Added FeO42- decomposes, by oxidizing a wide range of water contaminants including sulfides (demonstrated in this study) and other sulfur-containing compounds, cyanides (demonstrated in this study), arsenic (demonstrated in this study), ammonia and other nitrogen-containing compounds (previously demonstrated), a wide range of organics (phenol demonstrated in this study), algae, and viruses (each previously demonstrated).

  20. Ammonia-modified graphene sheets decorated with magnetic Fe{sub 3}O{sub 4} nanoparticles for the photocatalytic and photo-Fenton degradation of phenolic compounds under sunlight irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Boruah, Purna K. [Advanced Materials Group, Materials Sciences and Technology Division, CSIR-North East Institute of Science & Technology, Jorhat 785006 (India); Academy of Scientific and Innovative Research (AcSIR) (India); Sharma, Bhagyasmeeta [Advanced Materials Group, Materials Sciences and Technology Division, CSIR-North East Institute of Science & Technology, Jorhat 785006 (India); Karbhal, Indrapal; Shelke, Manjusha V. [Academy of Scientific and Innovative Research (AcSIR) (India); Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune-11008, Maharashtra (India); Das, Manash R., E-mail: mnshrdas@yahoo.com [Advanced Materials Group, Materials Sciences and Technology Division, CSIR-North East Institute of Science & Technology, Jorhat 785006 (India); Academy of Scientific and Innovative Research (AcSIR) (India)

    2017-03-05

    Highlights: • Ammonia-modified graphene sheets decorated with magnetic Fe{sub 3}O{sub 4} nanoparticles. • Photocatalytic and photo-Fenton degradation of phenolic compounds. • An excellent reusability of the nanocomposite was observed up to ten cycles. - Abstract: Synthesis of easily separable and eco-friendly efficient catalyst with both photocatalytic and photo-Fenton degradation properties is of great importance for environment remediation application. Herein, ammonia-modified graphene (AG) sheets decorated with Fe{sub 3}O{sub 4} nanoparticles (AG/Fe{sub 3}O{sub 4}) as a magnetically recoverable photocatalyst by a simple in situ solution chemistry approach. First, we have functionalized graphene oxide (GO) sheets by amide functional group and then Fe{sub 3}O{sub 4} nanoparticles (NPs) are doped onto the functionalized GO surface. The AG/Fe{sub 3}O{sub 4} nanocomposite showed efficient photocatalytic activity towards degradation of phenol (92.43%), 2-nitrophenol (2-NP) (98%) and 2-chlorophenol (2-CP) (97.15%) within 70–120 min. Consequently, in case of photo-Fenton degradation phenomenon, 93.56% phenol, 98.76% 2-NP and 98.06% of 2-CP degradation were achieved within 50–80 min using AG/Fe{sub 3}O{sub 4} nanocomposite under sunlight irradiation. The synergistic effect between amide functionalized graphene and Fe{sub 3}O{sub 4} nanoparticles (NPs) enhances the photocatalytic activity by preventing the recombination rate of electron-hole-pair in Fe{sub 3}O{sub 4} NPs. Furthermore, the remarkable reusability of the AG/Fe{sub 3}O{sub 4} nanocomposite was observed up to ten cycles during the photocatalytic degradation of these phenolic compounds.

  1. X-ray diffraction study of chalcopyrite CuFeS2, pentlandite (Fe,Ni)9S8 and Pyrrhotite Fe1-xS obtained from Cu-Ni orebodies

    International Nuclear Information System (INIS)

    Nkoma, J.S.; Ekosse, G.

    1998-05-01

    The X-ray Diffraction (XRD) technique is applied to study five samples of Cu-Ni orebodies, and it is shown that they contain chalcopyrite CuFeS 2 as the source of Cu, pentlandite (Fe,Ni) 9 S 8 as the source of Ni and pyrrhotite Fe 1-x S as a dominant compound. There are also other less dominant compounds such as bunsenite NiO, chalcocite Cu 2 S, penrosite (Ni, Cu)Se 2 and magnetite Fe 3 O 4 . Using the obtained XRD data, we obtain the lattice parameters for tetragonal chalcopyrite as a=b=5.3069A and c=10.3836A, cubic pentlandite as a=b=c=10.0487A, and hexagonal pyrrhotite as a=b=6.8820A and c=22.8037A. (author)

  2. Experimental phases diagram Zr-Fe and Zr-Sn-Fe of the Fe rich zone at a temperature of 1100oC

    International Nuclear Information System (INIS)

    Nieva, N.; Jimenez, J.; Gomez, A; Granovsky, M.S

    2010-01-01

    Zr-based alloys are frequently used in the nuclear energy industry; among these are the Zr-based Zircaloys whose main alloys are Sn and Fe. In order to experimentally evaluate part of the diagram of the binary Zr-Fe phases and the ternary Zr-Sn-Fe in the Fe-rich zone, different binary alloys in the area closest to the composition of the ZrFe 2 and Zr 6 Fe 23 compounds were designed as well as a ternary alloy of Zr-Sn-Fe in the Fe-rich region of the ternary system. All the alloys underwent a two month heat treatment at a temperature of 1100 o C. Later the phases that were present were identified using different complementary techniques (mainly X-ray diffraction and microanalysis). The clear presence of the Zr 6 Fe 23 phase was not observed in any of the alloys. A new ternary phase consisting approximately of Zr 2 0Sn 14 Fe 66 was verified in the ternary alloy

  3. Nature of impurities in fertilizers containing EDDHMA/Fe(3+), EDDHSA/Fe(3+), and EDDCHA/Fe(3+) chelates.

    Science.gov (United States)

    Alvarez-Fernández, Ana; Cremonini, Mauro A; Sierra, Miguel A; Placucci, Giuseppe; Lucena, Juan J

    2002-01-16

    Iron chelates derived from ethylenediaminedi(o-hydroxyphenylacetic) acid (EDDHA), ethylenediaminedi(o-hydroxy-p-methylphenylacetic) acid (EDDHMA), ethylenediaminedi(2-hydroxy-5-sulfophenylacetic) acid (EDDHSA), and ethylenediaminedi(5-carboxy-2-hydroxyphenylacetic) acid (EDDCHA) are remarkably efficient in correcting iron chlorosis in plants growing in alkaline soils. This work reports the determination of impurities in commercial samples of fertilizers containing EDDHMA/Fe(3+), EDDHSA/Fe(3+), and EDDCHA/Fe(3+). The active components (EDDHMA/Fe(3+), EDDHSA/Fe(3+), and EDDCHA/Fe(3+)) were separated easily from other compounds present in the fertilizers by HPLC. Comparison of the retention times and the UV-visible spectra of the peaks obtained from commercial EDDHSA/Fe(3+) and EDDCHA/Fe(3+) samples with those of standard solutions showed that unreacted starting materials (p-hydroxybenzenesulfonic acid and p-hydroxybenzoic acid, respectively) were always present in the commercial products. 1D and 2D NMR experiments showed that commercial fertilizers based on EDDHMA/Fe(3+) contained impurities having structures tentatively assigned to iron chelates of two isomers of EDDHMA. These findings suggest that current production processes of iron chelates used in agriculture need to be improved.

  4. Crystal structure of a two-dimensional grid-type iron(II coordination polymer: poly[[diaquatetra-μ-cyanido-diargentate(Iiron(II] trans-1,2-bis(pyridin-2-ylethylene disolvate

    Directory of Open Access Journals (Sweden)

    Jintana Othong

    2014-08-01

    Full Text Available In the title compound, {[Ag2Fe(CN4(H2O2]·2C12H10N2}n, the asymmetric unit contains one FeII cation, two water molecules, two dicyanidoargentate(I anions and two uncoordinating 1,2-bis(pyridin-2-ylethylene (2,2′-bpe molecules. Each FeII atom is six-coordinated in a nearly regular octahedral geometry by four N atoms from dicyanidoargentate(I bridges and two coordinating water molecules. The FeII atoms are bridged by dicyanidoargentate(I units to give a two-dimensional layer with square-grid spaces. The intergrid spaces with interlayer distance of 6.550 (2 Å are occupied by 2,2′-bpe guest molecules which form O—H...N hydrogen bonds to the host layers. This leads to an extended three-dimensional supramolecular architecture. The structure of the title compound is compared with some related compounds containing dicyanidoargentate(I ligands and N-donor organic co-ligands.

  5. 40 CFR Table 34 to Subpart G of... - Fraction Measured (Fm) and Fraction Emitted (Fe) For HAP Compounds in Wastewater Streams

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Fraction Measured (Fm) and Fraction... Vessels, Transfer Operations, and Wastewater Pt. 63, Subpt. G, Table 34 Table 34 to Subpart G of Part 63—Fraction Measured (Fm) and Fraction Emitted (Fe) For HAP Compounds in Wastewater Streams Chemical name CAS...

  6. Structural stability of ternary C22–Zr6X2Co (X=Al, Ga, Sn, As, Sb, Bi, Te) and C22–Zr6Sn2T′ (T′=Fe, Co, Ni, Cu) compounds

    International Nuclear Information System (INIS)

    Colinet, Catherine; Crivello, Jean-Claude; Tedenac, Jean-Claude

    2013-01-01

    The crystal and electronic structures, and the thermodynamic properties of Zr 6 X 2 Co (X=Al, Ga, Sn, As, Sb, Bi, Te) and Zr 6 Sn 2 T′ (T′=Fe, Co, Ni, Cu) ternary compounds in the Fe 2 P-type structure have been investigated by means of first principle calculations. The calculated structural parameters are in good agreement with the experimental data. The total electronic densities of states as well as the Bader charges of the atoms have been computed. Both electronic and size effects allow to explain the stability of the ternary Zr 6 X 2 Co (X=Al, Ga, Sn, As, Sb, Bi, Te) and Zr 6 Sn 2 T′ (T′=Fe, Co, Ni, Cu) compounds. - Graphical abstract: Valence charge electronic localization function (ELF) calculated for Zr 6 Sb 2 Co compound. Display Omitted - Highlights: • Structural stability of Zr 6 X 2 T′ compounds (X: p element, T′: late transition metal) in the Fe 2 P-type structure. • First principles calculation of lattice parameters and enthalpies of formation. • Electronic densities of state in the series Zr 6 Sn 2 T′ (T′=Fe, Co, Ni, Cu). • Electronic densities of state in the series Zr 6 X 2 Co (X=Al, Ga, Sn, As, Sb, Bi, Te)

  7. Features of magnetic and thermal properties of R(Co{sub 1−x}Fe{sub x}){sub 2} (x≤0.16) quasibinary compounds with R=Dy, Ho, Er

    Energy Technology Data Exchange (ETDEWEB)

    Anikin, Maksim; Tarasov, Evgeniy; Kudrevatykh, Nikolay [Institute of Natural Sciences, Ural Federal University, Ekaterinburg 620002 (Russian Federation); Inishev, Aleksander [Institute of Metal Physics, Ekaterinburg 620137 (Russian Federation); Semkin, Mikhail; Volegov, Aleksey; Zinin, Aleksander [Institute of Natural Sciences, Ural Federal University, Ekaterinburg 620002 (Russian Federation)

    2016-11-15

    In this work the results of measurements of high field susceptibility, paraprocess susceptibility and thermal properties of R(Co{sub 1−x}Fe{sub x}){sub 2} intermetallic compounds (R=Dy, Ho, Er and x=(0−0.16)) are presented (heat capacity and magnetocaloric effect (MCE)). A magnetic structure of the Ho(Co{sub 0.88}Fe{sub 0.12}){sub 2} at 293 K and 78 K was studied by neutron powder diffraction. Some peculiarities of a high-field susceptibility were revealed at low temperatures and around the Curie point (T{sub C}). In temperature range lower than T{sub C} by (100–150) K, magnetic contributions to a zero-field heat capacity were found. Studying MCE in wide temperatures range, the large change of the entropy magnetic contribution (∆S) was observed which correlates with ∆T phenomenon. In particular, for the Er(Co{sub 0.84}Fe{sub 0.16}){sub 2} compound the ∆S value at low temperatures is six times higher than that at Curie point. The possible reasons of such behavior were discussed. - Highlights: • Magnetic and magnetocaloric properties of R(Co–Fe){sub 2} compounds have been studied. • Fe introduction induces the disorientation effect in Ho-ions magnetic ordering. • Emergence of magnetic contribution to a heat capacity at temperatures less T{sub C}. • The existence of a broad maximum on a temperature dependence of the MCE. • Direct MCE measurements at magnetic field of (0–17.5) kOe have been performed.

  8. Synchrotron Diffraction Studies of Spontaneous Magnetostriction in Rare Earth Transition Metal Compounds

    International Nuclear Information System (INIS)

    Ning Yang

    2004-01-01

    Thermal expansion anomalies of R 2 Fe 14 B and R 2 Fe 17 C x (x = 0,2) (R Y, Nd, Gd, Tb, Er) stoichiometric compounds are studied with high-energy synchrotron X-ray powder diffraction using Debye-Schemer geometry in temperature range 10K to 1000K. Large spontaneous magnetostriction up to their Curie temperatures (T c ) is observed. The a-axes show relatively larger invar effects than c-axes in the R 2 Fe 14 B compounds whereas the R 2 Fe 17 C x show the contrary anisotropies. The iron sub-lattice is shown to dominate the spontaneous magnetostriction of the compounds. The contribution of the rare earth sublattice is roughly proportional to the spin magnetic moment of the rare earth in the R 2 Fe 14 B compounds but in R 2 Fe 17 C x , the rare earth sub-lattice contribution appears more likely to be dominated by the local bonding. The calculation of spontaneous magnetostrain of bonds shows that the bonds associated with Fe(j2) sites in R 2 Fe 14 B and the dumbbell sites in R 2 Fe 17 C x have larger values, which is strongly related to their largest magnetic moment and Wigner-Seitz atomic cell volume. The roles of the carbon atoms in increasing the Curie temperatures of the R 2 Fe 17 compounds are attributed to the increased separation of Fe hexagons. The R 2 Fe 17 and R 2 Fe 14 B phases with magnetic rare earth ions also show anisotropies of thermal expansion above T c . For R 2 Fe 17 and R 2 Fe 14 B the a a /a c > 1 whereas the anisotropy is reversed with the interstitial carbon in R 2 Fe 17 . The average bond magnetostrain is shown to be a possible predictor of the magnetic moment of Fe sites in the compounds. Both of the theoretical and phenomenological models on spontaneous magnetostriction are discussed and a Landau model on the spontaneous magnetostriction is proposed

  9. Effects of Ga substitution on the structural and magnetic properties of half metallic Fe{sub 2}MnSi Heusler compound

    Energy Technology Data Exchange (ETDEWEB)

    Pedro, S. S., E-mail: sandrapedro@uerj.br; Caraballo Vivas, R. J.; Andrade, V. M.; Cruz, C.; Paixão, L. S.; Contreras, C.; Costa-Soares, T.; Rocco, D. L.; Reis, M. S. [Instituto de Física, Universidade Federal Fluminense, Niterói-RJ (Brazil); Caldeira, L. [IF Sudeste MG, Campus Juiz de Fora - Núcleo de Física, Juiz de Fora-MG (Brazil); Coelho, A. A. [Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas - Unicamp, Campinas-SP (Brazil); Carvalho, A. Magnus G. [Laboratório Nacional de Luz Sincrotron, CNPEM, Campinas-SP (Brazil)

    2015-01-07

    The so-called half-metallic magnets have been proposed as good candidates for spintronic applications due to the feature of exhibiting a hundred percent spin polarization at the Fermi level. Such materials follow the Slater-Pauling rule, which relates the magnetic moment with the valence electrons in the system. In this paper, we study the bulk polycrystalline half-metallic Fe{sub 2}MnSi Heusler compound replacing Si by Ga to determine how the Ga addition changes the magnetic, the structural, and the half-metal properties of this compound. The material does not follow the Slater-Pauling rule, probably due to a minor structural disorder degree in the system, but a linear dependence on the magnetic transition temperature with the valence electron number points to the half-metallic behavior of this compound.

  10. Magnetocrystalline anisotropy and magnetic domain structure of ErFe11Ti and HoFe11Ti compounds

    International Nuclear Information System (INIS)

    Pastushenkov, Yury G.; Skokov, Konstantin P.; Skourski, Yury; Lebedeva, Ludmila; Ivanova, Tatyana; Grushichev, Anton; Mueller, Karl-Hartmut

    2006-01-01

    Tetragonal ThMn 12 -type single crystalline ErFe 11 Ti and HoFe 11 Ti samples have been investigated by magnetization measurements and by observations of the magnetic domain structure at various temperatures between 10 and 300K. The magnetic structure of ErFe 11 Ti changes from room temperature 'easy axis' (c-axis) type to conical at spin-reorientation temperature T SR =50K. The HoFe 11 Ti has a metastable anisotropy energy minimum in the a-direction at T<40K. It leads to a first-order magnetization process detected by magnetization measurements along the a-axis in this temperature region

  11. Magnetic and Random Anisotropy Studies in some Amorphous Fe-Based Compounds

    Science.gov (United States)

    Tlemçani, Mohamed; Benbachir, Khadija; Sayouri, Salaheddine; Meknassi, K.; Kadiri, H.

    2000-12-01

    We have studied the magnetization of melt spun amorphous Fe100-x-yCrx(PCSi)y alloys with 4≤x≤11 and 19≤y≤22 under magnetic fields up to 18 kOe, and have analyzed the results at 10 K in the framework of the phenomenological model of Chudnovsky and Serota. Behaviour of magnetic moment and exchange and anisotropy constants has been compared to that of the same parameters in amorphous FeNi(BSi), FeNiCr(BSi) and FeV(BSi).

  12. Progress of sintered NdFeB permanent magnets by the diffusion of non-rare earth elements and their alloy compounds

    Directory of Open Access Journals (Sweden)

    Lyu Meng

    2017-12-01

    Full Text Available It has been found that the coercivity (HC and corrosivity of sintered NdFeB magnets are closely related to the components and microstructure of their intergranular phase.The traditional smelting NdFeB magnets with adding heavy rare earth elements can modify intergranular phase to improve the HC and corrosion resistance of magnets.However,it makes the additives be homogenously distributed on the main phase,and causes magnetic decrease and cost increase.With the addition of non-rare earth materials into grain boundary,the microstructure of intergranular phase as well as its electrochemical potential and wettability can be optimized.As a result,the amount of heavy rare earth elements and cost of magnets could be reduced whilst the HC and corrosion resistance of magnets can be improved.This paper summarized the research on regulating the components and the microstructure of intergranular phase in sintered NdFeB magnets by non-rare earth metals and compounds,and its influence on coercivity and corrosion resistance.

  13. Robust and Selective Switching of an FeIII Spin-Crossover Compound on Cu2N/Cu(100) with Memristance Behavior.

    Science.gov (United States)

    Jasper-Toennies, Torben; Gruber, Manuel; Karan, Sujoy; Jacob, Hanne; Tuczek, Felix; Berndt, Richard

    2017-11-08

    The switching between two spin states makes spin-crossover molecules on surfaces very attractive for potential applications in molecular spintronics. Using scanning tunneling microscopy, the successful deposition of [Fe(pap) 2 ] + (pap = N-2-pyridylmethylidene-2-hydroxyphenylaminato) molecules on Cu 2 N/Cu(100) surface is evidenced. The deposited Fe III spin-crossover compound is controllably switched between three different states, each of them exhibiting a characteristic tunneling conductance. The conductance is therefore employed to readily read the state of the molecules. A comparison of the experimental data with the results of density functional theory calculations reveals that all Fe(pap) 2 molecules are initially in their high-spin state. The two other states are compatible with the low-spin state of the molecule but differ with respect to their coupling to the substrate. As a proof of concept, the reversible and selective nature of the switching is used to build a two-molecule memory.

  14. Hole doping by pressure on the 1111 pnictides CaFeAsF and SrFeAsF

    International Nuclear Information System (INIS)

    Freitas, Daniele C; Sow, Amadou; Núñez-Regueiro, Manuel; Garbarino, Gastón; Weht, Ruben; Zhu, Xiyu; Han, Fei; Cheng, Peng; Ju, Jing; Hu Wen, Hai

    2014-01-01

    We determine the pressure phase diagram of the 1111 compounds CaFeAsF and SrFeAsF, up to 20 GPa and down to 4 K by electrical resistivity measurements and the change of structure up to 40 GPa at room temperature. The antiferromagnetic transition temperature, as determined by the derivative peak, shows a minimum at ∼5 GPa (10 GPa) for the Ca (Sr) compound. For CaFeAsF, superconductivity appears at this minimum, coincident with the development of a previously reported monoclinic phase. For SrFeAsF, where the orthorhombic and the monoclinic phase were reported to coexist, superconductivity exists above P≥1 GPa. Both phase diagrams can be scaled by a shift of ∼10 GPa pressure at which the volume of SrFeAsF and that of CaFeAsF at ambient pressure coincide. The difference of our phase diagram with that of electron-doped 1111 samples is accounted for by hole doping under pressure, which we verified through electron band structure calculations. (papers)

  15. Optical study of Dirac fermions and related phonon anomalies in the antiferromagnetic compound CaFeAsF

    Science.gov (United States)

    Xu, B.; Xiao, H.; Gao, B.; Ma, Y. H.; Mu, G.; Marsik, P.; Sheveleva, E.; Lyzwa, F.; Dai, Y. M.; Lobo, R. P. S. M.; Bernhard, C.

    2018-05-01

    We performed optical studies on CaFeAsF single crystals, a parent compound of the 1111-type iron-based superconductors that undergoes a structural phase transition from tetragonal to orthorhombic at Ts=121 K and a magnetic one to a spin density wave (SDW) state at TN=110 K. In the low-temperature optical conductivity spectrum, after the subtraction of a narrow Drude peak, we observe a pronounced singularity around 300 cm-1 that separates two regions of quasilinear conductivity. We outline that these characteristic absorption features are signatures of Dirac fermions, similar to what was previously reported for the BaFe2As2 system [Z.-G. Chen et al., Phys. Rev. Lett. 119, 096401 (2017), 10.1103/PhysRevLett.119.096401]. In support of this interpretation, we show that for the latter system this singular feature disappears rapidly upon electron and hole doping, as expected if it arises from a van Hove singularity in between two Dirac cones. Finally, we show that one of the infrared-active phonon modes (the Fe-As mode at 250 cm-1) develops a strongly asymmetric line shape in the SDW state and note that this behavior can be explained in terms of a strong coupling with the Dirac fermions.

  16. Generation and evolution of nanoscale AlP and Al{sub 13}Fe{sub 4} particles in Al-Fe-P system

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Huan; Gao, Tong; Zhu, Xiangzhen; Wu, Yuying; Qian, Zhao; Liu, Xiangfa, E-mail: xfliu@sdu.edu.cn

    2015-02-15

    Highlights: • Diffusion and gradual solid reactions between Al and Fe{sub x}P phases in Al-Fe-P alloy were investigated. • Nanoscale AlP clusters are in-situ generated and evolve during the whole process. • This novel Al-Fe-P alloy has an excellent low-temperature refining performance on hypereutectic Al-Si alloy. - Abstract: In this paper, the gradual solid reactions between Al and Fe{sub x}P phases in Al-Fe-P alloy were investigated. The results show that the whole reaction process undergoes four main stages: the diffusion of Al atom, the generation of (Al, Fe, P) intermediate compound, the precipitation of nano AlP and Al{sub 13}Fe{sub 4} clusters and their growth to submicron particles. The microstructure of Fe-P particles evolves from the “egg-type”, the “sponge-type” to the “sesame-cake” structure. AlP and Al{sub 13}Fe{sub 4} nano phases have in-situ generated and evolved during the whole process. The gradual reaction mechanism has been discussed. Furthermore, a novel Al-Fe-P alloy which contains (Al, Fe, P) intermediate compounds and nano AlP particles has been synthesized and its low-temperature refining performance on A390 alloy has also been investigated.

  17. Oxygen stabilized rare-earth iron intermetallic compounds

    International Nuclear Information System (INIS)

    Dariel, M.P.; Malekzadeh, M.; Pickus, M.R.

    1975-10-01

    A new, oxygen-stabilized intermetallic compound was identified in sintered, pre-alloyed rare-earth iron powder samples. Its composition corresponds to formula R 12 Fe 32 O 2 and its crystal structure belongs to space group Im3m. The presence of these compounds was observed, so far, in several R--Fe--O systems, with R = Gd, Tb, Dy, Ho, Er, and Y

  18. In situ observation of the formation of FeSe

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Wulff, Anders Christian; Yue, Zhao

    2011-01-01

    The formation of the FeSe compound from a mixture of Fe and Se powders encased in a composite Cu/Nb sheath was studied in situ by means of high-energy synchrotron x-ray diffraction. Tetragonal beta-FeSe does not seem to form directly from the starting elements. Instead, a sequence of FeSe2, Fe3Se...

  19. Uniaxial-strain mechanical detwinning of CaFe2As2 and BaFe2As2 crystals: Optical and transport study

    International Nuclear Information System (INIS)

    Tanatar, M.A.; Blomberg, E.C.; Kreyssig, A.; Kim, M.G.; Ni, N.; Thaler, A.; Bud'ko, S.L.; Canfield, P.C.; Goldman, A.I.; Mazin, I.I.; Prozorov, R.

    2010-01-01

    The parent compounds of iron-arsenide superconductors, AFe 2 As 2 (A=Ca, Sr, Ba), undergo a tetragonal to orthorhombic structural transition at a temperature T TO in the range 135-205 K depending on the alkaline-earth element. Below T TO the free standing crystals split into equally populated structural domains, which mask intrinsic, in-plane, anisotropic properties of the materials. Here we demonstrate a way of mechanically detwinning CaFe 2 As 2 and BaFe 2 As 2 . The detwinning is nearly complete, as demonstrated by polarized light imaging and synchrotron x-ray measurements, and reversible, with twin pattern restored after strain release. Electrical resistivity measurements in the twinned and detwinned states show that resistivity, ρ, decreases along the orthorhombic a o axis but increases along the orthorhombic b o axis in both compounds. Immediately below T TO the ratio ρ bo /ρ ao = 1.2 and 1.5 for Ca and Ba compounds, respectively. Contrary to CaFe 2 As 2 , BaFe 2 As 2 reveals an anisotropy in the nominally tetragonal phase, suggesting that either fluctuations play a larger role above T TO in BaFe 2 As 2 than in CaFe 2 As 2 or that there is a higher temperature crossover or phase transition.

  20. Dissimilatory Fe(III) and Mn(IV) reduction.

    Science.gov (United States)

    Lovley, D R

    1991-06-01

    The oxidation of organic matter coupled to the reduction of Fe(III) or Mn(IV) is one of the most important biogeochemical reactions in aquatic sediments, soils, and groundwater. This process, which may have been the first globally significant mechanism for the oxidation of organic matter to carbon dioxide, plays an important role in the oxidation of natural and contaminant organic compounds in a variety of environments and contributes to other phenomena of widespread significance such as the release of metals and nutrients into water supplies, the magnetization of sediments, and the corrosion of metal. Until recently, much of the Fe(III) and Mn(IV) reduction in sedimentary environments was considered to be the result of nonenzymatic processes. However, microorganisms which can effectively couple the oxidation of organic compounds to the reduction of Fe(III) or Mn(IV) have recently been discovered. With Fe(III) or Mn(IV) as the sole electron acceptor, these organisms can completely oxidize fatty acids, hydrogen, or a variety of monoaromatic compounds. This metabolism provides energy to support growth. Sugars and amino acids can be completely oxidized by the cooperative activity of fermentative microorganisms and hydrogen- and fatty-acid-oxidizing Fe(III) and Mn(IV) reducers. This provides a microbial mechanism for the oxidation of the complex assemblage of sedimentary organic matter in Fe(III)- or Mn(IV)-reducing environments. The available evidence indicates that this enzymatic reduction of Fe(III) or Mn(IV) accounts for most of the oxidation of organic matter coupled to reduction of Fe(III) and Mn(IV) in sedimentary environments. Little is known about the diversity and ecology of the microorganisms responsible for Fe(III) and Mn(IV) reduction, and only preliminary studies have been conducted on the physiology and biochemistry of this process.

  1. Ruddlesden-Popper compounds (SrO)(LaFeO3)n (n = 1 and 2) as p-type semiconductors for photocatalytic hydrogen production

    International Nuclear Information System (INIS)

    Chen, Hongmei; Sun, Xiaoqin; Xu, Xiaoxiang

    2017-01-01

    Graphical abstract: Two layered ferrites LaSrFeO 4 and La 2 SrFe 2 O 7 have been investigated which demonstrate interesting p-type semconductivity and efficient hydrogen production from water. Display Omitted -- Abstract: Here we report two Ruddlesden-Popper type ferrite perovskites (SrO)(LaFeO 3 ) n (n = 1 and 2) which demonstrate p-type semiconductivity. Their crystal structure, optical absorption and other physicochemical properties have been systematically explored. Our results show that both ferrites crystallize in tetragonal symmetry with structural lamination along c axis. Efficient photocatalytic hydrogen production has been achieved for both samples under full range and visible light illumination. Better performance is noticed for LaSrFeO 4 with apparent quantum efficiency approaches 0.31% and 0.19% under full range and visible light illumination, respectively. The p-type semiconductivity is verified by their cathodic photocurrent as well as negative Mott-Schottky slop during Photoelectrochemical measurement. The relative lower activity for La 2 SrFe 2 O 7 compared to LaSrFeO 4 is likely due to its higher defect concentration which facilitates charge recombination. Both compounds exhibit anisotropic phenomenon for charge migrations according to theoretical calculations. Their p-type semiconductivity, strong visible light absorption, chemical inertness and high abundance of constituent elements signify promising applications in the field of solar energy conversion and optoelectronics.

  2. Phase composition of iron-rich R-Fe-Si (R=Dy, Ho, Er) alloys

    International Nuclear Information System (INIS)

    Ivanova, G.V.; Makarova, G.M.; Shcherbakova, E.V.; Belozerov, E.V.

    2005-01-01

    Phase composition is studied in iron-rich alloys of R-Fe-Si (R=Dy, Ho, Er). In the as-cast state R 2 (Fe, Si) 17 of type Th 2 Ni 17 and R(Fe, Si) 12 compounds are observed; in the alloys of rated composition of R(Fe 0.85 Si 0.15 ) 8.5 (R=Dy, Er) a compound R 2 (Fe, Si) 17 of Th 2 Zn 17 -type is revealed as well. The annealing at 1273 K results in formation of Dy 3 (Fe, Si) 29 and also the compounds with the presumed composition of Dy 4 (Fe, Si) 41 and Ho 4 (Fe, Si) 41 . As this takes place the alloys contain a transition structure as well that represents a set of small-sized areas with various type short-range order in mutual displacement of Fe-Fe(Si) dumpbell chains. The process of phase formation at 1273 K is faced with difficulties. Even the annealing for 1000 h does not result in the state of equilibrium [ru

  3. SiO2@FeSO4 nano composite: A recoverable nano-catalyst for eco-friendly synthesis oximes of carbonyl compounds

    Directory of Open Access Journals (Sweden)

    Mostafa Karimkoshteh

    2016-01-01

    Full Text Available Various aldoximes and ketoximes synthesis of corresponding aldehydes and ketones in the presence of SiO2@FeSO4 nano composite as recoverable nano catalyst and NH2OH·HCl. The SiO2@FeSO4 nano composite system was carried out between 10 to 15 min in oil bath (70-80 °C under solvent-free condition in excellent yields in addition this protocol can be used for industrial scales. This method offers some advantages in term of clean reaction conditions, easy work-up procedure, short reaction time, applied to convert α-diketones to α-diketoximes (as longer than other carbonyl compounds, α,β-unsaturated aldehydes and ketones to corresponding oximes and suppression of any side product. So we think that NH2OH•HCl/SiO2@FeSO4 nano composite system could be considered a new and useful addition to the present methodologies in this area. Structure of products and nano composite elucidation was carried out by 1H NMR, 13C NMR, FT-IR, scanning electron microscopy (SEM.

  4. Fabrication and characterization of nanostructured Fe3S4, an isostructural compound of half-metallic Fe3O4

    KAUST Repository

    Li, Peng; Xia, Chuan; Zhang, Qiang; Guo, Zaibing; Cui, Wenyao; Bai, Haili; Alshareef, Husam N.; Zhang, Xixiang

    2015-01-01

    High-purity, well-crystallized spinel Fe3S4 nanoplatelets were synthesized by the hydrothermal method, and the saturation magnetic moment of Fe3S4 was measured at 1.83 μB/f.u. The temperature-dependent resistivity of Fe3S4 was metallic

  5. Synchrotron Diffraction Studies of Spontaneous Magnetostriction in Rare Earth Transition Metal Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ning [Iowa State Univ., Ames, IA (United States)

    2004-12-19

    Thermal expansion anomalies of R2Fe14B and R2Fe17Cx (x = 0,2) (R = Y, Nd, Gd, Tb, Er) stoichiometric compounds are studied with high-energy synchrotron X-ray powder diffraction using Debye-Schemer geometry in temperature range 10K to 1000K. Large spontaneous magnetostriction up to their Curie temperatures (Tc) is observed. The a-axes show relatively larger invar effects than c-axes in the R2Fe14B compounds whereas the R2Fe17Cx show the contrary anisotropies. The iron sub-lattice is shown to dominate the spontaneous magnetostriction of the compounds. The contribution of the rare earth sublattice is roughly proportional to the spin magnetic moment of the rare earth in the R2Fe14B compounds but in R2Fe17Cx, the rare earth sub-lattice contribution appears more likely to be dominated by the local bonding. The calculation of spontaneous magnetostrain of bonds shows that the bonds associated with Fe(j2) sites in R2Fe14B and the dumbbell sites in R2Fe17Cx have larger values, which is strongly related to their largest magnetic moment and Wigner-Seitz atomic cell volume. The roles of the carbon atoms in increasing the Curie temperatures of the R2Fe17 compounds are attributed to the increased separation of Fe hexagons. The R2Fe17 and R2Fe14B phases with magnetic rare earth ions also show anisotropies of thermal expansion above c. For R2Fe17 and R2Fe14B the a a/a c > 1 whereas the anisotropy is reversed with the interstitial carbon in R2Fe17. The average bond magnetostrain is shown to be a possible predictor of the magnetic moment of Fe sites in the compounds. Both of the theoretical and

  6. Reaction /sup 56/Fe (. gamma. ,. cap alpha. /sub 0/) and /sup 56/Fe (. gamma. , p/sub 0/)

    Energy Technology Data Exchange (ETDEWEB)

    Tamae, T; Sugawara, M [Tohoku Univ., Sendai (Japan). Lab. of Nuclear Science; Tsubota, H

    1975-06-01

    Precise analysis was made on the cross section of the /sup 56/Fe (..gamma.., ..cap alpha../sub 0/) reaction and the angular distribution at Esub(e) = 17 MeV, including the systematic error. The (..gamma.., ..cap alpha../sub 0/) reaction cross section was compared with a calculation using the compound nucleus model, utilizing the photon absorption cross section derived from the experimental values of /sup 56/Fe (..gamma.., n) and /sup 56/Fe (..gamma.., p) cross sections. From the (..gamma.., ..cap alpha../sub 0/) reaction cross section data of various nuclei, an empirical formula was obtained for determining the position of a peak in the (..gamma.., ..cap alpha../sub 0/) reaction cross section. The /sup 56/Fe (..gamma.., p/sub 0/) reaction cross section measured at an excitation energy in the range of 14.6--25.0 MeV was compared with the calculated one with the compound nucleus model, but the form and size differ totally.

  7. Single peak parameters technique for simultaneous measurements: Spectrophotometric sequential injection determination of Fe(II) and Fe(III).

    Science.gov (United States)

    Kozak, J; Paluch, J; Węgrzecka, A; Kozak, M; Wieczorek, M; Kochana, J; Kościelniak, P

    2016-02-01

    Spectrophotometric sequential injection system (SI) is proposed to automate the method of simultaneous determination of Fe(II) and Fe(III) on the basis of parameters of a single peak. In the developed SI system, sample and mixture of reagents (1,10-phenanthroline and sulfosalicylic acid) are introduced into a vessel, where in an acid environment (pH≅3) appropriate compounds of Fe(II) and Fe(III) with 1,10-phenanthroline and sulfosalicylic acid are formed, respectively. Then, in turn, air, sample, EDTA and sample again, are introduced into a holding coil. After the flow reversal, a segment of air is removed from the system by an additional valve and as EDTA replaces sulfosalicylic acid forming a more stable colorless compound with Fe(III), a complex signal is registered. Measurements are performed at wavelength 530 nm. The absorbance measured at minimum of the negative peak and the area or the absorbance measured at maximum of the signal can be used as measures corresponding to Fe(II) and Fe(III) concentrations, respectively. The time of the peak registration is about 2 min. Two-component calibration has been applied to analysis. Fe(II) and Fe(III) can be determined within the concentration ranges of 0.04-4.00 and 0.1-5.00 mg L(-1), with precision less than 2.8% and 1.7% (RSD), respectively and accuracy better than 7% (RE). The detection limit is 0.04 and 0.09 mg L(-1) for Fe(II) and Fe(III), respectively. The method was applied to analysis of artesian water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Fabrication and characterization of nanostructured Fe3S4, an isostructural compound of half-metallic Fe3O4

    KAUST Repository

    Li, Peng

    2015-06-10

    High-purity, well-crystallized spinel Fe3S4 nanoplatelets were synthesized by the hydrothermal method, and the saturation magnetic moment of Fe3S4 was measured at 1.83 μB/f.u. The temperature-dependent resistivity of Fe3S4 was metallic-like for T < 180 K: room-temperature resistivity was measured at 7.711 × 103  μΩ cm. The anomalous Hall conductivity of Fe3S4 decreased with increasing longitudinal conductivity, in sharp contrast with the accepted theory of the anomalous Hall effect in a dirty-metal regime. Furthermore, negligible spin-dependent magnetoresistance was observed. Band structure calculations confirmed our experimental observations that Fe3S4 is a metal and not a half metal as expected.

  9. Comparing the characteristics of highly cited titles and highly alted titles

    Energy Technology Data Exchange (ETDEWEB)

    Didegah, F.; Bowman, T.D.; Bowman, S.; Hartley, J.

    2016-07-01

    This study examines differences in the types of titles for articles that show high altmetric activity (highly alted articles) versus highly cited articles. This work expands on previous research on document titles in combination with a grounded theory approach to develop a codebook in which articles were manually coded based on 11 characteristics. The results show that there are differences and similarities in titles across many of the examined characteristics; highly cited titles and highly mentioned titles on Wikipedia have some similar characteristics such as they have the the highest percentage of substantive words; in addition, there are no or very few titles referencing outside or with humor/lightness on both platforms. Twitter and Facebook also showed some similarities having the highest percentage of humorous/light titles and lowest percentage of substantive words in their titles. (Author)

  10. In situ study on the formation of FeTe

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Wulff, Anders Christian; Yue, Zhao

    2011-01-01

    The formation of the FeTe compound from a mixture of Fe and Te powders was studied in situ by means of high-energy synchrotron X-ray diffraction. FeTe does not form directly from the starting elements; instead, FeTe2 forms as an intermediate product. During a 2 °C/min heating ramp, Te first reacts...

  11. Structural and magnetic properties of transition metal substituted BaFe2As2 compounds studied by x-ray and neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Gyu [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    The purpose of my dissertation is to understand the structural and magnetic properties of the newly discovered FeAs-based superconductors and the interconnection between superconductivity, antiferromagnetism, and structure. X-ray and neutron scattering techniques are powerful tools to directly observe the structure and magnetism in this system. I used both x-ray and neutron scattering techniques on different transition substituted BaFe2As2 compounds in order to investigate the substitution dependence of structural and magnetic transitions and try to understand the connections between them.

  12. Thorium-d-metals compounds and solid solutions

    International Nuclear Information System (INIS)

    Chachkhiani, Z.B.; Chechernikov, V.I.; Chachkhiani, L.G.

    1986-01-01

    Thorium compounds with Fe, Co, Ni dependence of their magnetic properties on temperature, pressure and concentration of the second element are considered. Anomalous magnetic behaviour of alloys in the Th-Fe system is noted. Special attention is paid to compounds with CaCu 5 type hexagonal structure and their solid solutions. Th-Co-Ni specimens containing up to 25% Ni are ferromagnetics and the rest are paramagnetics. Specimens with 60% cobalt content do not display ferromagnetic properties up to 4.2 K. Hydrides of Th 7 M 3 H 30 type (M - Fe, Co, Ni) are also considered. Highly hydrogenized specimens (under high pressure) appear to be stronger ferromagnetics

  13. Moessbauer Study of the Ball Milling Disordering Process of FeAl Intermetallic Compounds

    International Nuclear Information System (INIS)

    Oleszak, Dariusz; Bruna, Pere; Crespo, Daniel; Pradell, Trinitat

    2005-01-01

    Structural changes during ball milling of ordered Fe50Al50 intermetallic compounds were studied. X-Ray diffraction allowed the computation of a Long Range Order parameter (LRO) which dropped to zero after a short milling time. The initial B2 ordered structure gradually transforms into a disordered BCC structure, with a final crystallite size of about 25 nm. Moessbauer spectroscopy was used for obtaining a Chemical Short Range Order parameter (CSRO). Using a semiempirical n-body noncentral potential a model of the partially disordered B2 structure was built allowing computing the distribution of Quadrupole Splitting during the disordering process. Comparison between experimental and simulated Moessbauer spectra shows a maximum of disorder in the system for 5h milling, related to the highest value of the lattice spacing and the broader quadrupole hyperfine distribution. However, after milling for times longer than 5h, there is a change on the behavior of the experimental data that cannot be explained by the simple disordering process

  14. Synthesis, structure and chemical bonding of CaFe{sub 2−x}Rh{sub x}Si{sub 2} (x=0, 1.32, and 2) and SrCo{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hlukhyy, Viktor, E-mail: viktor.hlukhyy@lrz.tu-muenchen.de; Hoffmann, Andrea V.; Fässler, Thomas F.

    2013-07-15

    }. The crystal chemistry and chemical bonding in the title compounds are discussed in terms of LMTO band structure calculations and a topological analysis using the Electron Localization Function (ELF). - Graphical abstract: The SrCo{sub 2}Si{sub 2} and CaFe{sub 2−x}Rh{sub x}Si{sub 2} (x==0, 1.32, and 2) crystallize in the ThCr{sub 2}Si{sub 2}-type. The structure of SrCo{sub 2}Si{sub 2} contains isolated [Co{sub 2}Si{sub 2}]{sup 2−} layers in the ab-plane, whereas the [T{sub 2}Si{sub 2}] layers in CaFe{sub 2−x}Rh{sub x}Si{sub 2} are interconnected along the c-axis via Si3Si bonds resulting in a [T{sub 2}Si{sub 2}]{sup 2−} network. - Highlights: • Synthesis and structure of ternary silicides SrCo{sub 2}Si{sub 2} and CaFe{sub 2−x}Rh{sub x}Si{sub 2} (x=0, 1.32, and 2). • The SrCo{sub 2}Si{sub 2} and CaRh{sub 2}Si{sub 2} are isoelectronic to the parent 122 iron–pnictide superconductors AeFe{sub 2}As{sub 2}. • CaFe{sub 2}Si{sub 2} is a full substituted variant (As/Si) of superconductor CaFe{sub 2}As{sub 2}. • The title compounds demonstrate the tunable Si3Si distances.

  15. Formation of Al70Cu20Fe10 icosahedral quasicrystal by mechanically alloyed method

    International Nuclear Information System (INIS)

    Yin Shilong; Bian Qing; Qian Liying; Zhang Aimei

    2007-01-01

    The structural evolutions of the mechanically alloyed ternary Al 70 Cu 20 Fe 10 powders with the milling time and the annealing treatment have been studied by X-ray diffraction (XRD), transmission electronic microscopy (TEM) and X-ray absorption fine-structure spectroscopy (XAFS) techniques. Results show that an Al 2 Cu compound forms with short-time milling, while a Cu 9 Al 4 compound forms with long-time milling. Fe can react with Al-Cu alloy by annealing treatment. Al 7 Cu 2 Fe compound with tetragonal structure or Al (Cu, Fe) solid solution with cubic structure may form at lower temperature, while a quasicrystal phase of Al 65 Cu 20 Fe 15 alloy may form at higher temperature

  16. Nanostructure and Volatile Organic Compounds Sensing Properties of α-Fe2O3/Reduced Graphene Oxide Nanocomposite Derived by Spray Method

    Science.gov (United States)

    Zolghadr, S.; Kimiagar, S.; Khojier, K.

    2017-12-01

    This paper investigates the α-Fe2O3/reduced graphene oxide (rGO) nanocomposite as a volatile organic compounds (VOCs) sensor. The α-Fe2O3/reduced graphene oxide nanocomposites of about 370 nm thickness were synthesized by a spray method with different rGO contents (3%, 4%, and 5%) on SiO2/Si substrates. The samples were structurally and morphologically characterized by x-ray diffraction, and field emission scanning electron microscopy. These analyses showed that an increase in rGO content decreases the crystallinity of the samples. In order to study the VOCs sensing properties, the sensitivity and selectivity of the samples were tested with different VOCs vapors including ethanol, methanol, toluene, benzene, and formic acid in the temperature range of 200-400°C. The results show that the α-Fe2O3/rGO nanocomposites are more selective to ethanol than the other vapors, while an increase in rGO content decreases the sensitivity of the samples. The α-Fe2O3/rGO (3%)-based ethanol sensor also shows a good stability with respect to relative humidity in the range of 20-50% with a 1-ppm detection limit at the operating temperature of 280°C.

  17. Hydrogen absorption in Zr(Alsub(x)Bsub(1-x))2 (B = Fe, Co) Laves phase compounds

    International Nuclear Information System (INIS)

    Jacob, I.; Shaltiel, D.

    1978-01-01

    The hydrogen absorption capacity of the systems Zr(Alsub(x)Fesub(1-x)) 2 and Zr(Alsub(x)Cosub(1-x)) 2 (0 = 2 (A = V, Cr, Mn; B = Fe, Co; 0 =< x =< 1). The maximum hydrogen content in both systems is achieved for x approximately 2/12 at 40 atm and 80 K. Further increase of the Al content leads, however, to a steep decrease in the hydrogen capacity. This general behaviour is well described by a phenomenological model, recently proposed by the authors, thus supporting the importance of short-range neighbouring effects for the hydrogen absorption capacity. The influence of Al on the hydrogen sorption properties in different intermetallic compounds is discussed. (author)

  18. Electronic properties of Fe2+ in MTiO3

    International Nuclear Information System (INIS)

    Ito, A.; Morimoto, S.

    1975-01-01

    Moessbauer spectra were observed in a temperature range from 4.2 to 300 K for the ilmenite structure compounds MTiO 3 -2 % 57 Fe (M = Mg, Mn-I, Fe, Co, Ni) and for the disordered ilmenite structure compound MnTiO 2 -II-1 % 57 Fe. The Neel temperature and the spin orientation of host materials are tabulated. A well resolved quadrupole doublet was observed for all the samples at temperatures above the respective Neel temperatures. Below the Neel temperature a magnetic structure appeared. The Moessbauer spectra obtained at 4.2 K are presented. The spectra were analyzed on the basis of the well-known Hamiltonian for sup(57m)Fe. Moessbauer parameters obtained are tabulated. Analyzing the spectra at 4.2 K, quadrupole interaction was determined to be negative in MnTiO 3 -II and positive in all other compounds. Hyperfine magnetic field intensities observed a6 4.2 K were 34, 85, 47, 105 and 91 kOe for MnTiO 3 -I, MnTiO 3 -II, FeTiO 3 , CoTiO 3 and NiTiO 3 , respectively. (Z.S.)

  19. The effects of Tb substitution for La on the magnetic properties of LaFe11.5Si1.5 compound

    Science.gov (United States)

    Imam, H.; Zhang, H. G.; Xu, L.; Zhao, J. L.; Gao, X. X.; Yue, M.

    2018-05-01

    The structural and magnetic properties of La1-yTbyFe11.5Si1.5 compounds have been investigated. The substituted 5 percent of Tb has remarkably increased the maximum entropy change (-ΔSM) to a value of 25.2 J/kg·K. However, a further increase of Tb leads to a monotonous decrease in the entropy change, mainly due to phase separation. The Tb substitution also can lower the thermal and magnetic hysteresis loss of the system. Another feature of this replacement is that, with Tb content higher than 10 percent, the Curie temperature (TC) starts to increase and reaches 197 K when 30 percent of La is substituted. These results indicate that La1-yTbyFe11.5Si1.5 may be a promising candidate for magnetic refrigeration material in certain temperature range.

  20. Crystal structures and magnetic properties of iron (III)-based phosphates: Na4NiFe(PO4)3 and Na2Ni2Fe(PO4)3

    International Nuclear Information System (INIS)

    Essehli, Rachid; Bali, Brahim El; Benmokhtar, Said; Bouziane, Khalid; Manoun, Bouchaib; Abdalslam, Mouner Ahmed; Ehrenberg, Helmut

    2011-01-01

    Graphical abstract: A perspective view of the Na 2 Ni 2 Fe(PO 4 ) 3 structure along the [0 0 1] direction. Both compounds seem to exibit antiferromagnetic interactions between magnetic entities at low temperature. Display Omitted Research highlights: → Nasicon and Alluaudite compounds, Iron(III)-based phosphates, Crystal structures of Na 4 NiFe(PO 4 ) 3 and Na 2 Ni 2 Fe(PO 4 ) 3 . → Magnetism behaviours of Na 4 NiFe(PO 4 ) 3 and Na 2 Ni 2 Fe(PO 4 ) 3 . → Antiferromagnetism interactions. → Mossbauer spectroscopy. - Abstract: Crystal structures from two new phosphates Na 4 NiFe(PO 4 ) 3 (I) and Na 2 Ni 2 Fe(PO 4 ) 3 (II) have been determined by single crystal X-ray diffraction analysis. Compound (I) crystallizes in a rhombohedral system (S. G: R-3c, Z = 6, a = 8.7350(9) A, c = 21.643(4) A, R 1 = 0.041, wR 2 =0.120). Compound (II) crystallizes in a monoclinic system (S. G: C2/c, Z = 4, a = 11.729(7) A, b = 12.433(5) A, c = 6.431(2) A, β = 113.66(4) o , R 1 = 0.043, wR 2 =0.111). The three-dimensional structure of (I) is closely related to the Nasicon structural type, consisting of corner sharing [(Ni/Fe)O 6 ] octahedra and [PO 4 ] tetrahedra forming [NiFe(PO 4 ) 3 ] 4+ units which align in chains along the c-axis. The Na + cations fill up trigonal antiprismatic sites within these chains. The crystal structure of (II) belongs to the alluaudite type. Its open framework results from [Ni 2 O 10 ] units of edge-sharing [NiO 6 ] octahedra, which alternate with [FeO 6 ] octahedra that form infinite chains. Coordination of these chains yields two distinct tunnels in which site Na + . The magnetization data of compound (I) reveal antiferromagnetic (AFM) interactions by the onset of deviations from a Curie-Weiss behaviour at low temperature as confirmed by Moessbauer measurements performed at 4.2 K. The corresponding temperature dependence of the reciprocal susceptibility χ -1 follows a typical Curie-Weiss behaviour for T > 105 K. A canted AFM state is proposed for

  1. Bacterial Electrocatalysis of K4[Fe(CN)6] Oxidation

    DEFF Research Database (Denmark)

    Zheng, Zhiyong; Xiao, Yong; Wu, Ranran

    Shewanella oneidensis MR-1 (MR-1), a model strain of electrochemically active bacteria, can transfer electrons from cell to extracellular electron acceptors including Fe(III) (hydro)oxides. It has been reported that several redox species such as cytochromes in membranes and flavins assist...... in the electron transport (ET) processes. However, the oxidization of metal compounds was barely described. Here we report electrocatalysis of K4[Fe(CN)6] oxidation by MR-1. K4[Fe(CN)6] is a redox inorganic compound and shows a reversible redox process on bare glassy carbon (GCE). This is reflected by a pair...

  2. Magnetic anisotropy and pressure dependence of the order temperature in the Gd3(FeTi)29 compound

    International Nuclear Information System (INIS)

    Morellon, L.; Arnold, Z.; Pareti, L.; Albertini, F.; Paoluzi, A.

    1995-01-01

    In this work we report ac initial magnetic susceptibility under pressure, singular point detection (SPD) and linear thermal expansion measurements in the Gd 3 (FeTi) 29 intermetallic compound. From these measurements we have determined the anisotropy field, the order temperature and its pressure dependence. The thermal expansion measurement shows an Invar-like anomaly at the order temperature, T C =520 K, which decreases under increasing pressure with a slope of dT C /dp=-2.7 K/kbar. As the Gd 3+ ion is isotropic, no contribution to the anisotropy from the 4f sublattice is expected and low values of the anisotropy fields have been observed. (orig.)

  3. Magnetic ordering in Sc{sub 2}CoSi{sub 2}-type R{sub 2}FeSi{sub 2} (R=Gd, Tb) and R{sub 2}CoSi{sub 2} (R=Y, Gd–Er) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Knotko, A.V. [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty, Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation); Pani, M. [Department of Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova (Italy); Institute SPIN-CNR, C. Perrone 24, 16152 Genova (Italy); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600036 (India); Quezado, S.; Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082-970 (Brazil)

    2016-09-01

    Magnetic and magnetocaloric properties of Sc{sub 2}CoSi{sub 2}-type R{sub 2}TSi{sub 2} (R=Gd–Er, T=Fe, Co) compounds have been studied using magnetization data. These indicate the presence of mixed ferromagnetic and antiferromagnetic interactions in these compounds. One observes a ferromagnetic transition followed by an antiferromagnetic order and a further possible spin-reorientation transition at low temperatures. Compared to Gd{sub 2}{Fe, Co}Si{sub 2}, the Tb{sub 2}FeSi{sub 2} and {Tb–Er}{sub 2}CoSi{sub 2} compounds exhibit remarkable hysteresis (for e.g. Tb{sub 2}FeSi{sub 2} shows residual magnetization M{sub res}/Tb=2.45 μ{sub B}, coercive field H{sub coer}=14.9 kOe, and critical field H{sub crit}~5 kOe at 5 K) possibly due to the magnetocrystalline anisotropy of the rare earth. The R{sub 2}{Fe, Co}Si{sub 2} show relatively small magnetocaloric effect (i.e. isothermal magnetic entropy change, ΔS{sub m}) around the magnetic transition temperature: the maximal value of MCE is demonstrated by Ho{sub 2}CoSi{sub 2} (ΔS{sub m}=−8.1 J/kg K at 72 K and ΔS{sub m}=−9.4 J/kg K at 23 K in field change of 50 kOe) and Er{sub 2}CoSi{sub 2} (ΔS{sub m}=−13.6 J/kg K at 32 K and ΔS{sub m}=−8.4 J/kg K at 12 K in field change of 50 kOe). - Highlights: • {Gd–Er}{sub 2}{Fe, Co}Si{sub 2} show high-temperature ferromagnetic-type transitions. • {Gd–Er}{sub 2}{Fe, Co}Si{sub 2} show low-temperature spin-reorientation transitions. • Tb{sub 2}FeSi{sub 2} and {Tb–Er}{sub 2}CoSi{sub 2} compounds exhibit low-temperature hysteresis. • Tb{sub 2}FeSi{sub 2} shows M{sub res}/Tb=2.45 μ{sub B}, H{sub coer}=14.9 kOe and H{sub crit} ~5 kOe at 5 K • Considerable magnetocaloric effect is exhibited by Ho{sub 2}CoSi{sub 2} and Er{sub 2}CoSi{sub 2}.

  4. Evolution of Iron-containing Compounds in Al-Cu Alloys during Heat Treatment

    Directory of Open Access Journals (Sweden)

    Liu Kun

    2016-01-01

    Full Text Available The evolution of iron-containing compounds in Al-Cu 206 cast alloy during solution treatment has been investigated. Results show that platelet β-Fe and Chinese script α-Fe are the two iron-containing compounds in as-cast condition. Little change is observed on β-Fe during solution treatment. However, fine blocky post β-Fe begins to form on α-Fe when solution treated at 520°C for 8hrs. When soaking time is extended to 24 hrs, α–Fe is found to decompose to fine branches while post β-Fe present as clusters on these branches. Al-Cu-Mg-Si Q phase is observed to form at the edge of decomposed α-Fe, possibly the result of Si from decomposed α-Fe.

  5. Thermodynamic analysis of (Ni, Fe)3Al formation by mechanical alloying

    International Nuclear Information System (INIS)

    Adabavazeh, Z.; Karimzadeh, F.; Enayati, M.H.

    2012-01-01

    Highlights: ► (Ni, Fe) 3 Al intermetallic compound was synthesized by mechanical alloying. ► We use a thermodynamic analysis to predict the more stable phase. ► We calculate the Gibbs free-energy changes by using extended Miedema model. ► The results of MA compared with thermodynamic analysis and showed a good agreement with it. - Abstract: (Ni, Fe) 3 Al intermetallic compound was synthesized by mechanical alloying (MA) of Ni, Fe and Al elemental powder mixtures of composition Ni 50 Fe 25 Al 25 . Phase transformation and microstructure characteristics of the alloy powders were investigated by X-ray diffraction (XRD). The results show that mechanical alloying resulted in a Ni (Al, Fe) solid solution. By continued milling, this structure transformed to the disordered (Ni, Fe) 3 Al intermetallic compound. A thermodynamic model developed on the basis of extended theory of Miedema is used to calculate the Gibbs free-energy changes. Final product of MA is a phase having minimal Gibbs free energy compared with other competing phases in Ni–Fe–Al system. However in Ni–Fe–Al system, the most stable phase at all compositions is intermetallic compound (not amorphous phase or solid solution). The results of MA were compared with thermodynamic analysis and revealed the leading role of thermodynamic on the formation of MA product prediction.

  6. Magnetocrystalline anisotropy and magnetic domain structure of ErFe{sub 11}Ti and HoFe{sub 11}Ti compounds

    Energy Technology Data Exchange (ETDEWEB)

    Pastushenkov, Yury G. [Physics Department of Tver State University, 17000 Tver (Russian Federation); Skokov, Konstantin P. [Physics Department of Tver State University, 17000 Tver (Russian Federation); Skourski, Yury [Leibniz-Institute for Solid State and Material Research, 01171 Dresden (Germany); Lebedeva, Ludmila [Physics Department of Tver State University, 17000 Tver (Russian Federation); Ivanova, Tatyana [Physics Department of Moscow Stae University, 119889 Moscow (Russian Federation); Grushichev, Anton [Physics Department of Tver State University, 17000 Tver (Russian Federation)]. E-mail: yupast@tversu.ru; Mueller, Karl-Hartmut [Leibniz-Institute for Solid State and Material Research, 01171 Dresden (Germany)

    2006-05-15

    Tetragonal ThMn{sub 12}-type single crystalline ErFe{sub 11}Ti and HoFe{sub 11}Ti samples have been investigated by magnetization measurements and by observations of the magnetic domain structure at various temperatures between 10 and 300K. The magnetic structure of ErFe{sub 11}Ti changes from room temperature 'easy axis' (c-axis) type to conical at spin-reorientation temperature T{sub SR}=50K. The HoFe{sub 11}Ti has a metastable anisotropy energy minimum in the a-direction at T<40K. It leads to a first-order magnetization process detected by magnetization measurements along the a-axis in this temperature region.

  7. Evolution of Primary Fe-Rich Compounds in Secondary Al-Si-Cu Alloys

    Science.gov (United States)

    Fabrizi, Alberto; Capuzzi, Stefano; Timelli, Giulio

    Although iron is usually added in die cast Al-Si foundry alloys to prevent die soldering, primary Fe-rich particles are generally considered as "hardspot" inclusions which compromise the mechanical properties of the alloy, namely ductility and toughness. As there is no economical methods to remove the Fe excess in secondary Al-Si alloys at this time, the control of solidification process and chemical composition of the alloy is a common industrial practice to overcome the negative effects connected with the presence of Fe-rich particles. In this work, the size and morphology as well as the nucleation density of primary Fe-rich particles have been studied as function of cooling rate and alloy chemical composition for secondary Al-Si-Cu alloys. The solidification experiments were carried out using differential scanning calorimetry whereas morphology investigations were conducted using optical and scanning electron microscopy. Mcrosegregations and chemical composition of primary Fe-rich particles were examined by energy dispersive spectroscopy.

  8. Structural stability of ternary C22–Zr{sub 6}X{sub 2}Co (X=Al, Ga, Sn, As, Sb, Bi, Te) and C22–Zr{sub 6}Sn{sub 2}T′ (T′=Fe, Co, Ni, Cu) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Colinet, Catherine, E-mail: ccolinet@simap.grenoble-inp.fr [Science et Ingénierie des Matériaux et Procédés, Grenoble INP, UJF, CNRS, 38402 Saint Martin d’Hères, Cedex (France); Crivello, Jean-Claude [ICMPE-CMTR, CNRS UMR-7182, 2-8 rue Henri Dunant, 94320 Thiais (France); Tedenac, Jean-Claude [Institut de Chimie Moléculaire et des Matériaux I.C.G., UMR-CNRS 5253, Université Montpellier II, Place E. Bataillon, 34095 Montpellier Cedex 5 (France)

    2013-09-15

    The crystal and electronic structures, and the thermodynamic properties of Zr{sub 6}X{sub 2}Co (X=Al, Ga, Sn, As, Sb, Bi, Te) and Zr{sub 6}Sn{sub 2}T′ (T′=Fe, Co, Ni, Cu) ternary compounds in the Fe{sub 2}P-type structure have been investigated by means of first principle calculations. The calculated structural parameters are in good agreement with the experimental data. The total electronic densities of states as well as the Bader charges of the atoms have been computed. Both electronic and size effects allow to explain the stability of the ternary Zr{sub 6}X{sub 2}Co (X=Al, Ga, Sn, As, Sb, Bi, Te) and Zr{sub 6}Sn{sub 2}T′ (T′=Fe, Co, Ni, Cu) compounds. - Graphical abstract: Valence charge electronic localization function (ELF) calculated for Zr{sub 6}Sb{sub 2}Co compound. Display Omitted - Highlights: • Structural stability of Zr{sub 6}X{sub 2}T′ compounds (X: p element, T′: late transition metal) in the Fe{sub 2}P-type structure. • First principles calculation of lattice parameters and enthalpies of formation. • Electronic densities of state in the series Zr{sub 6}Sn{sub 2}T′ (T′=Fe, Co, Ni, Cu). • Electronic densities of state in the series Zr{sub 6}X{sub 2}Co (X=Al, Ga, Sn, As, Sb, Bi, Te)

  9. Determination of K shell fluorescence cross-section and Kβ/Kα intensity ratios for Fe, Se, Te, FeSe, FeTe and TeSe

    International Nuclear Information System (INIS)

    Saydam, M.; Aksoy, C.; Cengiz, E.; Alaşalvar, C.; Tıraşoğlu, E.; Apaydın, G.

    2012-01-01

    The fluorescence cross-sections (σ Ki ) and the intensity ratios K β /K α for pure Fe, Se, Te elements and FeSe, FeTe, TeSe complexes have been investigated. The samples were excited by 59.5 keV γ-rays from 241 Am annular radioactive source and emitted X-rays. They were counted by an Ultra-LEGe detector with resolution of 150 eV at 5.9 keV. For pure elements results have been compared with the theoretical calculated values. According to our results band length and mutual interaction of atoms affected the results. We claimed that these effects would help researchers who study on superconductors, especially determining which compound can be show the superconductor properties. - Highlights: ► TeSe, FeSe and FeTe complexes have affected each other in terms of charge transfer. ► Fe excitement and enhancement have been made by Se and Te. ► Attractive interactions between electrons can help to becoming superconductivity.

  10. Fe2(AsO4)F: A new three-dimensional condensed fluoro-arsenate iron(II) compound with antiferromagnetic interactions

    International Nuclear Information System (INIS)

    Berrocal, Teresa; Mesa, Jose L.; Pizarro, Jose L.; Urtiaga, Miren K.; Arriortua, Maria I.; Rojo, Teofilo

    2006-01-01

    Fe 2 (AsO 4 )F has been synthesized under mild hydrothermal conditions in the form of single crystals. The compound crystallizes in C2/c monoclinic space group with the unit cell parameters a=13.214(1), b=6.623(1), c=10.045(1)A and β=116.90(2) deg. with Z=8. The crystal structure consists of a three-dimensional framework constructed by two kinds of chains, A and B, with 50% of population. In the chains, the environments for the iron(II) cations show penta- and hexa-coordination. The chains establish an angle of approximately 120 deg. between them. The disordered fluoride anions in these chains given rise to [Fe(1)O 4 F(1) 0.5 (F(2) 0.5 ) 2 ] and [Fe(2)O 4 (F(1) 0.5 ) 2 F(2) 0.5 ] edge-shared polyhedra in which the fluoride anions have occupancy factors of 50% over two distinct crystallographic sites. The IR spectrum shows the characteristic bands of the (AsO 4 ) 3- groups. From the diffuse reflectance spectrum a D q parameter of 650cm -1 has been calculated for the Fe(II) d 6 high spin cation. The Mossbauer spectrum in the paramagnetic state shows a doublet that has been fitted, according to the existence of two crystallographically independent iron environments, with two Lorentzian doublets. Magnetic measurements performed between room temperature and 5K exhibit a maximum at 22.6K, characteristic of antiferromagnetic interactions with a estimated 'J'-exchange parameter of -1.2K

  11. Magnetism and metal insulator transition in FeSi and FeGe. Ab Initio investigations of the electronic structure; Magnetismus und Metall-Isolator-Uebergang in FeSi und FeGe. Ab-initio-Untersuchungen der elektronischen Struktur

    Energy Technology Data Exchange (ETDEWEB)

    Neef, Matthias

    2007-03-19

    Aim of this thesis was to reach by a systematic study of different ab initio procedures an improved description of the electronic properties of FeSi and FeGe. Central result is the itinerant description of FeSi as a semiconductor in the neighbourhood of a ferromagnetic instability. The regardment of the nonlocal exchange in the effective one-particle approximation leads to a metastable magnetic state scarcely above the magnetic ground state. The application of the hybrid functional leads to a 1st order metal-isolator transition for large lattice parameters: FeSi transforms at increasement of the lattice parameter from an unmagnetic isolator to a magnetic metal. A similar behavior is found in the isostructural compound FeGe. The two systems FeSi and FeGe were systematically and detailedly analyzed by means of ab initio procedures. Thereby the structural, electronic, and magnetic properties were studied with DFT and HF calculations. Both calculations with spin polarization and without spin polarization were performed.

  12. RESEARCH CONCERNING THE Fe CIRCUIT IN THE ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    MARIOARA NICOLETA FILIMON

    2007-01-01

    Full Text Available The iron is an organogenous chemical element which, although in small quantities, is absolutely needed for live. The iron can be present in nature under 2 forms: bivalent or trivalent. Microorganism has an important role concerning the iron circuit in the biosphere. The iron cycle has 4 microbial processes: mineralizing the organic iron, forming the organic compounds with iron, the bivalent iron oxidity and the reduction of the trivalent iron. The Fe III and Fe II reduction, under the action of iron reductive bacteria, has a biological significance and a special a practical importance. Several proceedings used in mining, pottery and in the discovery of toxicity of certain compounds, at the level of anaerobic environment, are based on this process of reduction. The Fe III and Fe II reductive process can also have dangerous negative effects, due to the huge quantity of the accumulated Fe II. This huge quantity of Fe II is a big problem for the level of underground water, because Fe II compromises the water quality and the damaged metal plumbing. Under the action of microbial population, the trivalent iron is reduced to bivalent one, which is soluble. The bivalent iron is mostly evidenced with α,α-dipiridil reactive.

  13. Spin and lattice structures of single-crystalline SrFe2As2

    Science.gov (United States)

    Zhao, Jun; Ratcliff, W., II; Lynn, J. W.; Chen, G. F.; Luo, J. L.; Wang, N. L.; Hu, Jiangping; Dai, Pengcheng

    2008-10-01

    We use neutron scattering to study the spin and lattice structure of single-crystal SrFe2As2 , the parent compound of the FeAs-based superconductor (Sr,K)Fe2As2 . We find that SrFe2As2 exhibits an abrupt structural phase transition at 220 K, where the structure changes from tetragonal with lattice parameters c>a=b to orthorhombic with c>a>b . At almost the same temperature, Fe spins develop a collinear antiferromagnetic structure along the orthorhombic a axis with spin direction parallel to this a axis. These results are consistent with earlier work on the RFeAsO ( R=rare earth) families of materials and on BaFe2As2 , and therefore suggest that static antiferromagnetic order is ubiquitous for the parent compounds of these FeAs-based high-transition temperature superconductors.

  14. Studies of coal liquefaction (50). Catalysis of iron compounds

    Energy Technology Data Exchange (ETDEWEB)

    Tamura, Tomoyuki; Ogata, Eisuke; Kamiya, Yoshio

    1956-10-23

    A study is made to determine the catalytic actions and changes in grain size and surface area of various iron compound catalysts used for hydrogenation of phenanthrene. Effects of oxygen-containing compounds on the reaction are also investigated. Reactions of phenanthrene or CLB samples are performed in decalin or 1-methylnaphthalene as solvent. The solid reaction residue, including the catalyst used, is filtered and washed in acetone to provide specimens for SEM, surface area measurement (BET) and XRD. Three of the iron catalysts examined, CGS, FE(CO)/sub 5/ and FeS/sub 2/, are found to be highly effective for both phenanthrene hydrogenation and CLB decomposition, while Fe/sub 3/C does not work effectively for either of them. Fe (zero valene) and Fe/sub 2/O/sub 3/ are found effective for phenanthrene hydrogenation but not for CLB decomposition. (7 tabs)

  15. Alcoholic beverages induce superconductivity in FeTe1-xSx

    International Nuclear Information System (INIS)

    Deguchi, K; Kawasaki, Y; Ozaki, T; Tsuda, S; Yamaguchi, T; Takano, Y; Mizuguchi, Y

    2011-01-01

    We found that hot alcoholic beverages were effective in inducing superconductivity in FeTe 0.8 S 0.2 . Heating the FeTe 0.8 S 0.2 compound in various alcoholic beverages enhances the superconducting properties compared to a pure water-ethanol mixture as a control. Heating with red wine for 24 h leads to the largest shielding volume fraction of 62.4% and the highest zero resistivity temperature of 7.8 K. Some components present in alcoholic beverages, other than water and ethanol, have the ability to induce superconductivity in the FeTe 0.8 S 0.2 compound.

  16. Electronic structure and magnetic properties of Pd sub(3)Fe

    International Nuclear Information System (INIS)

    Kuhnen, C.A.

    1988-01-01

    In this work we study the electronic and magnetic properties of the Pd sub(3)Fe alloy. For the ordered phase of Pd sub(3)Fe we employed the Linear Muffin-Tin Orbitals Method, with the atomic sphere approximation, which is a first principles method and includes spin polarization. The theoretical results for the thermal and magnetic properties show good agreement with experience. Here we explain the formation of the localized magnetic moments from completely itinerant electrons. We investigate the influence of the hydrogen in the physical properties of the compound Pd sub(3)Fe, where we obtain a drastic reduction in the magnetic moments at the Pd and Fe sites. This reduction is confirmed by experience. The self consistent potentials of the Pd sub(3)Fe compound were used for an analysis of the influence of the disorder in the electronic structure of Pd sub(3)Fe alloy. To this end, we employ a spin polarized version of the Green's Function Method with the Coherent Potential Approximation (or KKR-CPA). The results obtained show that in random ferromagnetic alloys different degrees of disorder occurs for the different spin directions. The formation of the magnetic moments in these alloys were explained from the existence of 'virtual crystal' states for spin up electrons and 'split band' states for spin down electrons. Finally we employ the muffin-tin orbitals to calculate the X-ray photoemission spectra of the Pd sub(3)Fe and Pd sub(3)FeH compounds, which allows us a direct comparison between theory and experiment. (author)

  17. Thermodynamic properties of Y/sub 3/Fe/sub 5/O/sub 12/ and TbFeO/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Shchelkotunov, V A; Danilov, V N; Reznitskii, L A; Korobeinikova, A V [Moskovskij Gosudarstvennyj Univ. (USSR)

    1975-01-01

    Two types of chemical compounds-garnets and perovskites - exist in Fe/sub 2/O/sub 3/-Y/sub 2/O/sub 3/ and Fe/sub 2/O/sub 3/-Tb/sub 2/..omega../sub 3/ systems. Both of them are noncompensated antiferromagnetics. Thermal-physical properties of TbFeO/sub 3/ were determined. Values of Csub(p),(Hsub(t)-Hsub(o)) and Ssub(T) in the temperature range 298 to 700 deg K for Y/sub 3/Fe/sub 5/O/sub 12/ and in the range 298 to 600 deg K for TbFeO/sub 3/ were calculated using the experimental data on TbFeO/sub 3/ and Y/sub 3/Fe/sub 5/O/sub 12/ thermal capacity. Magnetic contribution for Y/sub 3/Fe/sub 5/O/sub 12/ Usub(mag)=1617 cal/mol and ..delta..S=3.44 cal/mol.deg. was determined.

  18. Crystal structure and Mössbauer studies of the isotypic Fe6-cluster compounds RE15[Fe8C25], RE=Dy, Ho

    KAUST Repository

    Davaasuren, Bambar

    2015-05-01

    The carboferrates RE15[Fe8C25] (RE=Dy, Ho) were prepared from mixtures of the elements by arc-melting followed with subsequent annealing at 1373 K. The crystal structures were determined from single crystal X-ray diffraction data and revealed an isotypic relationship to Er15[Fe8C25] (hP48, P321). The main feature of the crystal structure is given by Fe6 cluster units characterized by covalent Fe-Fe bonding interactions. 57Fe Mössbauer spectra of Dy15[Fe8C25] were fitted by three subspectra with relative spectral weights of about 3:3:2 which is in general agreement with the crystal structure. Below 50 K, an onset of magnetic hyperfine fields at the three iron sites is observed which is supposed to be caused by dipolar fields arising from neighboring, slowly relaxing Dy magnetic moments.

  19. Surface half-metallicity of half-Heusler compound FeCrSe and interface half-metallicity of FeCrSe/GaP

    Energy Technology Data Exchange (ETDEWEB)

    Khalaf Al-zyadi, Jabbar M., E-mail: jabbar_alzyadi@yahoo.com [Department of Physics, College of Education for Pure Sciences, University of Basrah (Iraq); Jolan, Mudhahir H. [Department of Physics, College of Education for Pure Sciences, University of Basrah (Iraq); Yao, Kai-Lun, E-mail: klyao@mail.hust.edu.cn [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); International Center of Materials Physics, Chinese Academy of Sciences, Shenyang 110015 (China)

    2016-04-01

    Recent studies showed that half-Heusler FeCrSe exhibits half-metallic ferromagnetism (Huang et al. [20]). In this paper, we investigate extensively the electronic, magnetic, and half-metallic properties of the half-Heusler alloy FeCrSe (111) and (001) surfaces and the interface with GaP (111) substrate by using the first-principles calculations within the density functional theory. The atomic density of states demonstrates that the half-me tallicity verified in the bulk FeCrSe is maintained at the CrSe-terminated (001) and Se-terminated (111) surfaces, but lost at both Cr- and Fe-terminated (111) surfaces and the Fe-terminated (001) surface. Alternatively, for the interface of FeCrSe/GaP (111), the bulk half-metallicity is destroyed at Se–P configuration while Se–Ga interface and subinterface show nearly 100% spin polarization. Moreover, the calculated interfacial adhesion energies exhibit that Se–Ga shape is more stable than the Se–P one. The calculated magnetic moments of Se, Ga at the Se–Ga (111) interface and P at the Se–P (111) interface increase with respect to the corresponding bulk values while the atomic magnetic moment of Se atom at the Se–P (111) interface decreases. We also notice that the magnetic moments of subinterface Fe at both Se–Ga and Se–P (111) interfaces decrease compared to the bulk values. - Highlights: • The half-metallicity verified in the bulk FeCrSe is kept at the CrSe-terminated (001) and Se-terminated (111) surfaces. • The calculated interfacial adhesion energies exhibit that Se–Ga shape is more stable than Se–P. • The magnetic moments of Se, Ga and P atoms at the interface increase. • The Se–Ga interface shows nearly 100% spin polarization.

  20. Influence of particle size and fluorination ratio of CFx precursor compounds on the electrochemical performance of C–FeF2 nanocomposites for reversible lithium storage

    Directory of Open Access Journals (Sweden)

    Ben Breitung

    2013-11-01

    Full Text Available Systematical studies of the electrochemical performance of CFx-derived carbon–FeF2 nanocomposites for reversible lithium storage are presented. The conversion cathode materials were synthesized by a simple one-pot synthesis, which enables a reactive intercalation of nanoscale Fe particles in a CFx matrix, and the reaction of these components to an electrically conductive C–FeF2 compound. The pretreatment and the structure of the utilized CFx precursors play a crucial role in the synthesis and influence the electrochemical behavior of the conversion cathode material. The particle size of the CFx precursor particles was varied by ball milling as well as by choosing different C/F ratios. The investigations led to optimized C–FeF2 conversion cathode materials that showed specific capacities of 436 mAh/g at 40 °C after 25 cycles. The composites were characterized by Raman spectroscopy, X-Ray diffraction measurements, electron energy loss spectroscopy and TEM measurements. The electrochemical performances of the materials were tested by galvanostatic measurements.

  1. Synthesis and crystal structure of Fe[(Te1.5Se0.5)O5]Cl, the first iron compound with selenate(IV) and tellurate(IV) groups

    Science.gov (United States)

    Akhrorov, Akhmad Yu; Kuznetsova, Elena S.; Aksenov, Sergey M.; Berdonosov, Peter S.; Kuznetsov, Alexey N.; Dolgikh, Valery A.

    2017-12-01

    During the search for selenium analogues of FeTe2O5Cl, the new iron (III) tellurate(IV) selenate(IV) chloride with the composition Fe[(Te1.5Se0.5)O5]Cl was synthesized by chemical vapor transport (CVT) reaction and characterized by TGA-, EDX-,SCXRD-analysis, as well as IR and Raman spectroscopy. It was found that Fe[(Te1.5Se0.5)O5]Cl crystallizes in the monoclinic space group P21/c with unitcell parameters a = 5.183(3) Å, b = 15.521(9) Å, c = 7.128(5) Å and β = 107.16(1)°. The crystal structure of Fe[(Te1.5Se0.5)O5]Cl represents a new structure type and contains electroneutral heteropolyhedral layers formed by dimers of the [FeO5Cl]8- octahedra, linked via common O-O edges, and mixed [Te3SeO10]4- tetramers. Adjacent layers are stacked along the b axis and linked by weak residual bonds. The new compound is stable up to 420 °C. DFT calculations predict Fe[(Te1.5Se0.5)O5]Cl to be a wide-gap semiconductor with the band gap of ca. 2.7 eV.

  2. Collapse of ferromagnetism in itinerant-electron system: A magnetic, transport properties, and high pressure study of (Hf,Ta)Fe2 compounds

    Science.gov (United States)

    Diop, L. V. B.; Kastil, J.; Isnard, O.; Arnold, Z.; Kamarad, J.

    2014-10-01

    The magnetism and transport properties were studied for Laves (Hf,Ta)Fe2 itinerant-electron compounds, which exhibit a temperature-induced first-order transition from the ferromagnetic (FM) to the antiferromagnetic (AFM) state upon heating. At finite temperatures, the field-induced metamagnetic phase transition between the AFM and FM has considerable effects on the transport properties of these model metamagnetic compounds. A large negative magnetoresistance of about 14% is observed in accordance with the metamagnetic transition. The magnetic phase diagram is determined for the Laves Hf1-xTaxFe2 series and its Ta concentration dependence discussed. An unusual behavior is revealed in the paramagnetic state of intermediate compositions, it gives rise to the rapid increase and saturation of the local spin fluctuations of the 3d electrons. This new result is analysed in the frame of the theory of Moriya. For a chosen composition Hf0.825Ta0.175Fe2, exhibiting such remarkable features, a detailed investigation is carried out under hydrostatic pressure up to 1 GPa in order to investigate the volume effect on the magnetic properties. With increasing pressure, the magnetic transition temperature TFM-AFM from ferromagnetic to antiferromagnetic order decreases strongly non-linearly and disappears at a critical pressure of 0.75 GPa. In the pressure-induced AFM state, the field-induced first-order AFM-FM transition appears and the complex temperature dependence of the AFM-FM transition field is explained by the contribution from both the magnetic and elastic energies caused by the significant temperature variation of the amplitude of the local Fe magnetic moment. The application of an external pressure leads also to the progressive decrease of the Néel temperature TN. In addition, a large pressure effect on the spontaneous magnetization MS for pressures below 0.45 GPa, dln(Ms)/dP = -6.3 × 10-2 GPa-1 was discovered. The presented results are consistent with Moriya

  3. Infrared investigation of the phonon spectrum in the frustrated spin cluster compound FeTe{sub 2}O{sub 5}Cl

    Energy Technology Data Exchange (ETDEWEB)

    Pfuner, F; Degiorgi, L [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zuerich (Switzerland); Berger, H; Forro, L [Institut de Physique de la Matiere Complexe (IPMC), EPF Lausanne, CH-1015 Lausanne (Switzerland)

    2009-09-16

    We present our optical investigations on the frustrated spin cluster compound FeTe{sub 2}O{sub 5}Cl, which develops a long-range antiferromagnetic order below 10 K. We measure the optical reflectivity from the far-infrared to the ultraviolet with polarized light. We focus our attention on the lattice dynamics by discussing the infrared-active modes. Our findings reveal a polarization dependence of the vibrational modes but which do not seem to be affected by structural anomalies linked to the magnetically ordered state at low temperatures.

  4. Pressure induced helimagnetism in Fe-based (Y.sub.2./sub.Fe.sub.17./sub., Lu.sub.2./sub.Fe.sub.17./sub.) intermetallic compounds

    Czech Academy of Sciences Publication Activity Database

    Kamarád, Jiří; Prokhnenko, Olexandr; Prokeš, K.; Arnold, Zdeněk; Andreev, Alexander V.

    2007-01-01

    Roč. 310, - (2007), s. 1801-1803 ISSN 0304-8853 R&D Projects: GA ČR GA202/06/0178 Institutional research plan: CEZ:AV0Z10100521 Keywords : magnetic structure * Fe-base intermetallics * Y 2 Fe 17 * pressure effects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.704, year: 2007

  5. Synthesis, crystal structure and biological activity of a novel 1,2,3-thidiazole compound

    International Nuclear Information System (INIS)

    Ke, W.

    2013-01-01

    A new 1,2,3-thiadiazole compound was synthesized and characterized by 1H NMR, MS and HRMS. The crystal structure of the title compound (C/sub 12/H/sub 11/ClN/sub 2/O/sub 4/S/sub 2/, Mr = 346.80) has been determined by single-crystal X-ray diffraction. The crystal is of triclinic, space group P-1 with a = 8.4425(17) A, b = 8.9801(18) A, c = 9.859(2) A, alpha = 84.36(3) degree, beta = 86.71(3)degree, lambda = 83.25(3) degree, V = 737.9(3)A3, Z 2, F(000) = 356, Dc = 1.561 g/cm/sup 3/, mu = 0.557 mm-1, the final R1 0.0380 and wR2 = 0.0982 for 2160 observed reflections with I > 2sigma(I). A total of 12585 reflections were collected, of which 2601 were independent (Rint 0.0364). The herbicidal activity of title compound was determined, the results showed the title compound displayed excellent herbicidal activity against Brassica campestris. (author)

  6. Crystal growth of Sm0.3Tb0.7FeO3 and spin reorientation transition in Sm1−xTbxFeO3 orthoferrite

    International Nuclear Information System (INIS)

    Wu, Anhua; Wang, Bo; Zhao, Xiangyang; Xie, Tao; Man, Peiwen; Su, Liangbi; Kalashnikova, A.M.; Pisarev, R.V.

    2017-01-01

    In this work, Sm 0.3 Tb 0.7 FeO 3 single crystal was successfully grown by optical floating zone method. Sm 0.3 Tb 0.7 FeO 3 samples with a-, b-, and c-orientation were manufactured by means of Laue photograph. Magnetic properties of Sm 0.3 Tb 0.7 FeO 3 single crystals are studied over a wide temperature range from 2 to 400 K. Spin reorientation transition from Γ 2 to Γ 4 are observed by means of the temperature dependence of magnetization It indicated the reorientation transition temperature of Sm 1−x Tb x FeO 3 single crystals is lowered with the contents of Tb contents rising based on this work and our previous works, thus the spin reorientation transition temperature can be adjusted through changing the compound in orthoferrites materials, which means that we can get orthoferrites single crystals with high magnetism property in various temperature through material design. - Highlights: • Sm 0.3 Tb 0.7 FeO 3 single crystals with various compounds were successfully grown by optical floating zone method. • The relation between SRT temperature and composition in Sm 1−x Tb x FeO 3 orthoferrite was indicated. • The spin reorientation transition temperature of Sm 1−x Tb x FeO 3 single crystals can be adjusted through changing the compound in orthoferrites materials.

  7. Identification of chemical compounds in a liquid-liquid extraction system

    International Nuclear Information System (INIS)

    Ramirez C, F de M de la.

    1980-01-01

    The objective of the present work is to identify the chemical compounds that are distributed in a liquid-liquid extraction system in which the third phase is observed; for this purpose the FeCl 3 (0.12M) - HCl (8.43M) - Diisopropilic ether - system was used, for the quantitative determination of the chemical compounds, FeCl 3 solutions labelled with 59 Fe or witH 38 Cl were used; the Karl Fischer method for the determination of the water concentration at the organic phases was used, the obtained data was used for the calculations of the H + distribution in each phase. The results are that when the distribution equilibrium is reached, the aqueous phase is a 7.5M HCl solution; the light organic phase contains 2 H[FeCl 4 ].6H 2 O and the dense organic phase contains 2 H[FeCl 4 ].6H 2 O.3HCl.12H 2 O. The differences between these compounds are due to a high concentration of water and the HCl in the organic solvent. This causes a heterogeneous physic field, and then the third phase formation. (author)

  8. Structural characterization of a new vacancy ordered perovskite modification found for Ba3Fe3O7F (BaFeO2.333F0.333): Towards understanding of vacancy ordering for different perovskite-type ferrites

    International Nuclear Information System (INIS)

    Clemens, Oliver

    2015-01-01

    The new vacancy ordered perovskite-type compound Ba 3 Fe 3 O 7 F (BaFeO 2.33 F 0.33 ) was prepared by topochemical low-temperature fluorination of Ba 2 Fe 2 O 5 (BaFeO 2.5 ) using stoichiometric amounts of polyvinylidene difluoride (PVDF). The vacancy order was found to be unique so far for perovskite compounds, and the connectivity pattern can be explained by the formula Ba 3 (FeX 6/2 ) (FeX 5/2 ) (FeX 3/2 X 1/1 ), with X=O/F. Mössbauer measurements were used to confirm the structural analysis and agree with the presence of Fe 3+ in the above mentioned coordination environments. Group–subgroup relationships were used to build a starting model for the structure solution and to understand the relationship to the cubic perovskite structure. Furthermore, a comparison of a variety of vacancy-ordered iron-containing perovskite-type structures is given, highlighting the factors which favour one structure type over the other depending on the composition. - Graphical abstract: The crystal structure of Ba 3 Fe 3 O 7 F in comparison to other perovskite type ferrites. - Highlights: • The crystal structure of Ba 3 Fe 3 O 7 F in comparison to other perovskite type ferrites. • Ba 3 Fe 3 O 7 F was synthesized by low temperature fluorination of Ba 2 Fe 2 O 5 . • Ba 3 Fe 3 O 7 F shows a unique vacancy order not found for other perovskite type compounds. • The structure of Ba 3 Fe 3 O 7 F was solved using group–subgroup relationships. • A systematic comparison to other ferrite type compounds reveals structural similarities and differences. • The A-site coordination of the cation is shown to play an important role for the type of vacancy order found

  9. 42 CFR 476.86 - Correlation of Title XI functions with Title XVIII functions.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 4 2010-10-01 2010-10-01 false Correlation of Title XI functions with Title XVIII functions. 476.86 Section 476.86 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF...) Qio Review Functions § 476.86 Correlation of Title XI functions with Title XVIII functions. (a...

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

    Directory of Open Access Journals (Sweden)

    de Julián Fernández C.

    2013-01-01

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

  11. Diffusion mechanisms in intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Larikov, L N [ANU, Inst. Metallofiziki, Kiev (Ukraine)

    1992-08-01

    Recent research aimed at the identification of the principal mechanisms of diffusion in intermetallics is reviewed. In particular, attention is given to the effect of the type of interatomic bond on the contribution of different mechanisms to diffusion in ordered metallic compounds. Results of an analysis of experimental determinations of diffusion coefficients D(A) and D(B) in binary intermetallics (CuZn, Cu3Sn, AuCd, AgZn, AgMg, InSb, GaSb, AlSb, Fe3Al, FeAl, FeAl3, Ni3Al, Ni3Nb, FeSn, FeSn2, Ni3Sn2, Ni3Sn4, Co3Sn2, CoSn, CoSn2, and CoGa) are presented, and it is shown that the D(A)/D(B) ratio differs substantially for different diffusion mechanisms. 60 refs.

  12. Preparation of Mg2FeH6 Nanoparticles for Hydrogen Storage Properties

    Directory of Open Access Journals (Sweden)

    N. A. Niaz

    2013-01-01

    Full Text Available Magnesium (Mg and iron (Fe nanoparticles are prepared by thermal decomposition of bipyridyl complexes of metals. These prepared Mg-Fe (2 : 1 nanoparticles are hydrogenated under 4 MPa hydrogen pressure and 673 K for 48 hours to achieve Mg2FeH6. Their structural analysis was assessed by applying manifold techniques. The hydrogen storage properties of prepared compound were measured by Sieverts type apparatus. The desorption kinetics were measured by high pressure thermal desorption spectrometer (HP-TDS. More than 5 wt% hydrogen released was obtained by the Mg2FeH6 within 5 min, and during rehydrogenation very effective hydrogen absorption rate was observed by the compound.

  13. 20 CFR 404.535 - How much will we withhold from your title VIII and title XVI benefits to recover a title II...

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false How much will we withhold from your title... Officer § 404.535 How much will we withhold from your title VIII and title XVI benefits to recover a title II overpayment? (a) If past-due benefits are payable to you, we will withhold the lesser of the...

  14. Synthesis and characterisation of the Fe(II-III) hydroxy-formate green rust

    International Nuclear Information System (INIS)

    Refait, P.; Abdelmoula, M.; Genin, J.-M. R.; Jeannin, M.

    2006-01-01

    A new methodology was envisioned in order to prepare green rust compounds build on organic anions that could intervene in microbiologically influenced corrosion processes of iron and steel. The formate ion was chosen as an example. The formation of rust was simulated by the oxidation of aqueous suspensions of Fe(OH) 2 precipitated from Fe(II) lactate and sodium hydroxide, in the presence of sodium formate to promote the formation of the corresponding green rust. The evolution of the precipitate with time was followed by transmission Moessbauer spectroscopy at 15 K. It was observed that the initial hydroxide was transformed into a new GR compound. Its spectrum is composed of three quadrupole doublets, D 1 (δ = 1.28 mm s -1 , Δ = 2.75 mm s -1 ) and D 2 (δ = 1.28 mm s -1 , Δ 2.48 mm s -1 ) that correspond to Fe(II) and D 3 (δ = 0.49 mm s -1 , Δ = 0.37 mm s -1 ) that corresponds to Fe(III). The relative area of D 3 , close to the proportion of Fe(III) in the GR, was found at 28.5 ± 1.5% (∼2/7). Raman spectroscopy confirmed that the intermediate compound was a Fe(II-III) hydroxy-formate, GR(HCOO - ).

  15. Influence of Zr substitution on the stabilization of ThMn12-type (Nd1−αZrα(Fe0.75Co0.2511.25Ti0.75N1.2−1.4 (α = 0–0.3 compounds

    Directory of Open Access Journals (Sweden)

    N. Sakuma

    2016-05-01

    Full Text Available The influence of Zr substitution in ThMn12 compounds was investigated using strip casting alloys. It was found that Zr substitution stabilized (Nd1−αZrα(Fe0.75Co0.2511.25Ti0.75N1.2−1.4 (α = 0–0.3 compounds. Specifically, a reduction in the lattice constant along the a-axis was observed. Energy-dispersive X-ray spectroscopy mapping combined with Cs-corrected scanning transmission electron microscopy indicated that Zr atoms preferentially occupied Nd 2a sites. Both the magnetic anisotropy field and saturation polarization were maximum at Zr substitution ratio α = 0.1. The (Nd1−αZrα(Fe0.75Co0.2511.25Ti0.75N1.2−1.4 (α = 0–0.3 compounds displayed higher saturation polarization than Nd2Fe14B at high temperatures.

  16. Unraveling the Role of Structural Order in the Transformation of Electrical Conductivity in Ca2FeCoO6-δ, CaSrFeCoO6-δ, and Sr2FeCoO6-δ.

    Science.gov (United States)

    Hona, Ram Krishna; Huq, Ashfia; Ramezanipour, Farshid

    2017-12-04

    The ability to control the electrical conductivity of solid-state oxides using structural parameters has been demonstrated. A correlation has been established between the electrical conductivity and structural order in a series of oxygen-deficient perovskites using X-ray and neutron diffraction, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and electrical conductivity studies at a wide temperature range, 25-800 °C. The crystal structure of CaSrFeCoO 6-δ has been determined, and its stark contrast to Ca 2 FeCoO 6-δ and Sr 2 FeCoO 6-δ has been demonstrated. The Fe/Co distribution over tetrahedral and octahedral sites has been determined using neutron diffraction. There is a systematic increase in the structural order in progression from Sr 2 FeCoO 6-δ (δ = 0.5) to CaSrFeCoO 6-δ (δ = 0.8) and Ca 2 FeCoO 6-δ (δ = 0.9) . The oxygen contents of these materials were determined using iodometric titration and TGA. At room temperature, there is an inverse correlation between the electrical conductivity and structural order. The ordered Ca 2 and CaSr compounds are semiconductors, while the disordered Sr 2 compund shows metallic behavior. The metallic nature of the Sr 2 material persists up to 1073 K (800 °C), while the Ca 2 and CaSr compounds undergo a semiconductor-to-metal transition above 500 and 300 °C, respectively, highlighting another important impact of the structural order. At high temperature, the CaSr compound has the highest conductivity compared to the Ca 2 and Sr 2 materials. There appears to be an optimum degree of structural order that leads to the highest conductivity at high temperature. Another consequence of the structural order is the observation of mixed ionic-electronic conductivity in CaSr and Ca 2 compounds, as is evident from the hysteresis in the conductivity data obtained during heating and cooling cycles. The average ionic radius required for each structural transition was

  17. Magnetic properties of CaCu{sub 5}-type RNi{sub 3}TSi (R=Gd and Tb, T=Mn, Fe, Co and Cu) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Knotko, A.V. [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty, Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation); Yao, Jinlei [Research Center for Solid State Physics and Materials, School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009 (China); Yuan, Fang; Mozharivskyj, Y. [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600036 (India); Quezado, S.; Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082-970 (Brazil)

    2015-12-15

    Magnetic properties and magnetocaloric effect of CaCu{sub 5}-type RNi{sub 3}TSi (R=Gd and Tb, T=Mn, Fe, Co and Cu) compounds have been investigated. Magnetic measurements of RNi{sub 3}TSi display the increasing of Curie temperature and the decreasing of magnetocaloric effect and saturated magnetic moment in the row of ‘RNi{sub 3}CuSi–RNi{sub 3}NiSi–RNi{sub 3}CoSi–RNi{sub 3}MnSi–RNi{sub 3}FeSi’. In contrast to GdNi{sub 3}{Mn, Fe, Co}Si, TbNi{sub 3}{Mn, Fe, Co}Si exhibit significant magnetic hysteresis. The coercive field increases from TbNi{sub 4}Si (~0.5 kOe) to TbNi{sub 3}CoSi (4 kOe), TbNi{sub 3}MnSi (13 kOe) and TbNi{sub 3}FeSi (16 kOe) in field of 50 kOe at 5 K, whereas TbNi{sub 3}CuSi exhibits a negligible coercive field. - Graphical abstract: Magnetic measurements of RNi{sub 3}TSi show the increasing of Curie temperature and the decreasing of magnetocaloric effect and saturated magnetic moment in the row of 'RNi{sub 3}CuSi–RNi{sub 3}NiSi–RNi{sub 3}CoSi–RNi{sub 3}MnSi–RNi{sub 3}FeSi'. In contrast to GdNi{sub 3}{Mn, Fe, Co}Si, TbNi{sub 3}{Mn, Fe, Co}Si exhibit significant magnetic hysteresis. The coercive field increases from TbNi{sub 4}Si (~0.5 kOe) to TbNi{sub 3}CoSi (4 kOe), TbNi{sub 3}MnSi (13 kOe) and TbNi{sub 3}FeSi (16 kOe) in field of 50 kOe at 5 K, whereas TbNi{sub 3}CuSi exhibits a negligible coercive field. - Highlights: • CaCu{sub 5}-type RNi{sub 3}TSi show ferromagnetic ordering (R=Gd, Tb, T=Mn–Co, Cu). • Curie point increases in ‘RNi{sub 3}CuSi–RNi{sub 3}NiSi–RNi{sub 3}CoSi–RNi{sub 3}MnSi–RNi{sub 3}FeSi’ row. • MCE decreases in ‘RNi{sub 3}CuSi–RNi{sub 3}NiSi–RNi{sub 3}CoSi–RNi{sub 3}MnSi–RNi{sub 3}FeSi’ row. • TbNi{sub 3}{Mn, Fe, Co}Si exhibit significant magnetic hysteresis. • The coercive field of TbNi{sub 3}MnSi and TbNi{sub 3}FeSi reach 13 kOe and 16 kOe at 5 K.

  18. Tunable magnetic properties by interfacial manipulation of L1(0)-FePt perpendicular ultrathin film with island-like structures.

    Science.gov (United States)

    Feng, C; Wang, S G; Yang, M Y; Zhang, E; Zhan, Q; Jiang, Y; Li, B H; Yu, G H

    2012-02-01

    Based on interfacial manipulation of the MgO single crystal substrate and non-magnetic AIN compound, a L1(0)-FePt perpendicular ultrathin film with the structure of MgO/FePt-AIN/Ta was designed, prepared, and investigated. The film is comprised of L1(0)-FePt "magnetic islands," which exhibits a perpendicular magnetic anisotropy (PMA), tunable coercivity (Hc), and interparticle exchange coupling (IEC). The MgO substrate promotes PMA of the film because of interfacial control of the FePt lattice orientation. The AIN compound is doped to increase the difference of surface energy between FePt layer and MgO substrate and to suppress the growth of FePt grains, which takes control of island growth mode of FePt atoms. The AIN compound also acts as isolator of L1(0)-FePt islands to pin the sites of FePt domains, resulting in the tunability of Hc and IEC of the films.

  19. Studies of the yields of 57Fe(II)-species produced after the EC-decay and of 60Co(II)-species produced in the (n, γ) reaction in cobalt(III) coordination compounds

    International Nuclear Information System (INIS)

    Sano, Hirotoshi; Harada, Masayuki; Endo, Kazutoyo

    1978-01-01

    The yields of 57 Fe(II)-species produced after EC-decay were compared with those of 60 Co(II)-species produced in the 59 Co(n, γ) 60 Co reaction for twelve cobalt(III) coordination compounds. The results indicate that the radiochemical yield of 60 Co(II)-species correlates with the yield of 57 Fe(II)-species except in the case of [Co(NH 3 ) 6 ] 2 (CrO 4 ) 3 . The anomalously low yield of 57 Fe(II)-species in [Co(NH 3 ) 6 ] 2 (CrO 4 ) 3 is ascribed to the reaction of chromate anions with ammine ligands initiated by the nuclear transformation in a solid. (author)

  20. Special Heusler compounds for spintronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Balke, B.

    2007-07-01

    This work emphasizes the potential of Heusler compounds in a wide range of spintronic applications. Using electronic structure calculations it is possible to design compounds for specific applications. Examples for GMR and TMR applications, for spin injection into semiconductors, and for spin torque transfer applications will be shown. After a detailed introduction about spintronics and related materials chapter 5 reports about the investigation of new half-metallic compounds where the Fermi energy is tuned in the middle of the gap to result in more stable compounds for GMR and TMR applications. The bulk properties of the quaternary Heusler alloy Co{sub 2}Mn{sub 1-x}Fe{sub x}Si with the Fe concentration ranging from x=0 to 1 are reported and the results suggest that the best candidate for applications may be found at an iron concentration of about 50%. Due to the effect that in the Co{sub 2}Mn{sub 1-x}Fe{sub x}Si series the transition metal carrying the localized moment is exchanged and this might lead to unexpected effects on the magnetic properties if the samples are not completely homogeneous chapter 6 reports about the optimization of the Heusler compounds for GMR and TMR applications. The structural and magnetic properties of the quaternary Heusler alloy Co{sub 2}FeAl{sub 1-x}Si{sub x} with varying Si concentration are reported. From the combination of experimental (better order for high Si content) and theoretical findings (robust gap at x=0.5) it is concluded that a compound with an intermediate Si concentration close to x=0.5-0.7 would be best suited for spintronic applications, especially for GMR and TMR applications. In chapter 7 the detailed investigation of compounds for spin injection into semiconductors is reported. It is shown that the diluted magnetic semiconductors based on CoTiSb with a very low lattice mismatch among each other are interesting materials for spintronics applications like Spin-LEDs or other spin injection devices. Chapter 8 refers

  1. Internal Displacement Reactions in Multicomponent Oxides: Part I. Line Compounds with Narrow Homogeneity Range

    OpenAIRE

    Reddy, SNS; Leonard, DN; Wiggins, LB; Jacob, KT

    2005-01-01

    As a model of an internal displacement reaction involving a ternary oxide line compound, the following reaction was studied at 1273 K as a function of time, t: $Fe+NiTiO_3 = Ni + FeTiO_3$ Both polycrystalline and single-crystal materials were used as the starting $NiTiO_3$ oxide. During the reaction, the Ni in the oxide compound is displaced by Fe and it precipitates as a \\gamma -(Ni-Fe) alloy. The reaction preserves the starting ilmenite structure. The product oxide has a consta...

  2. Ab initio calculation of electronic structure and magnetic properties of R2Fe14BNx (R = Pr,Nd)

    Science.gov (United States)

    Tian, Guang; Zha, Liang; Yang, Wenyun; Qiao, Guanyi; Wang, Changsheng; Yang, Yingchang; Yang, Jinbo

    2018-05-01

    The site preference of N atom for R2Fe14BNx (R= Pr, Nd) and the interstitial nitrogen effect on the magnetic properties have been studied by the first-principles method. It was found that the nitrogen is more likely to occupy the 4e site for Pr2Fe14BNx compound, while 4f site for Nd2Fe14BNx. When N atoms entering some specific crystal sites (such as 2a and 4f), the total magnetic moments of these compounds are not reduced, but slightly increased. Although the doping of N may reduce the total magnetic moments of some R2Fe14B compounds in the cases of optimal occupancy, the volumetric effect caused by N doping can still change the electron density distributions of Fe near the Fermi level, improving the magnetic ordering temperature of such compounds.

  3. CoFeRh alloys

    International Nuclear Information System (INIS)

    Tabakovic, Ibro; Qiu Jiaoming; Riemer, Steve; Sun Ming; Vas'ko, Vlad; Kief, Mark

    2008-01-01

    The electrochemical behavior of Rh(III) species in CoFe solution containing RhCl 3 , NH 4 Cl, H 3 BO 3 , CoSO 4 , FeSO 4 , saccharin, and NaLS (Na lauryl sulfate) has been investigated. The electrochemistry of Rh(III) species is influenced by each of the compounds present in CoFe plating solution, but especially by addition of saccharin and H 3 BO 3 to the RhCl 3 -NH 4 Cl solution. The nucleation and growth of Rh on GC (glassy carbon), Ru, and Cu electrodes from NH 4 Cl solution was studied using the potentiostatic current-transient methods. The results support a predominantly progressive nucleation of Rh on all three-electrode surfaces. The nucleation kinetic parameters ANo (steady state nucleation rate) and Ns (saturation nuclear number density) were found to vary with potential and are electrode-dependent in order: GC > Ru∼Cu. The electrodeposited Rh films obtained from NH 4 Cl solution and nonmagnetic CoFeRh film obtained from CoFe solution were characterized in terms of the following properties: morphology, surface roughness, crystal structure and chemical composition. The origin of light elements found in Rh and CoFeRh films (O, Cl, S, C, N) was discussed

  4. First-principles investigation of Cr-doped Fe2B: Structural, mechanical, electronic and magnetic properties

    Science.gov (United States)

    Wei, Xiang; Chen, Zhiguo; Zhong, Jue; Wang, Li; Wang, Yipeng; Shu, Zhongliang

    2018-06-01

    The structural, mechanical, electronic and magnetic properties of Fe8-xCrxB4 (x = 0, 0.25, 0.5, 1, 2, 3, 4, 5, 6, 7 and 8) have been investigated by first-principles calculation. It was found that the calculated structural parameters are well consistent with available experimental data. Moreover, all studied compounds are thermodynamically stable phases. On the whole, the moduli of the compounds firstly increase and then decrease with the increase of Cr concentration, whereas the variation of hardness exhibits more fluctuations. All Cr-doped Fe2B have better ductility than Fe2B except Fe2Cr6B4 and Fe5Cr3B4. Interestingly, Fe4Cr4B4 is of not only the slightly larger hardness, but also much better ductility than Fe2B. As the Cr concentration is lower than 20 wt%, the hardness of Cr-doped Fe2B slightly decreases with increasing Cr, whereas the sharply increased hardness of (Fe, Cr)2B in Fe-B alloys or boriding layer should be attributed to the multiple alloying effects resulting from Cr and the other alloying elements. The electronic structures revealed that the Fe-B and/or Cr-B bonds are mainly responsible for their mechanical properties, and the M-N (M = Fe or Cr, N = Fe or Cr) bonds in 〈2 2 0〉 and 〈1 1 3〉 orientations show covalent character. Additionally, the magnetic moments (Ms) of the compounds do not monotonically decrease with increasing Cr.

  5. Neutron-scattering study of the magnetic structure of DyFe4Al8 and HoFe4Al8

    DEFF Research Database (Denmark)

    Paixao, J.A.; Silva, M.R.; Sørensen, S.Aa.

    2000-01-01

    The magnetic structures of DyFe4Al8 and HoFe4Al8, which have been reported to be unusual spin-glass systems, were studied in detail by neutron diffraction, using both unpolarized and polarized beams. In fact these compounds have long-range magnetic order in both the Fe and rare-earth sublattices....

  6. THE WIDESPREAD OF Fe(III)-REDUCING BACTERIA IN NATURAL ECOSYSTEMS OF ECUADOR.

    Science.gov (United States)

    Tashyrev, O B; Govorukha, V M

    2015-01-01

    The widespread of Fe(III)-reducing microorganisms in natural ecosystems of Ecuador of La Favorita, Tungurahua volcano and Papallacta areas was experimentally proved. High efficiency of microbial precipitation of soluble iron compounds was also demonstrated. Obtained results indicate the potential ability of Fe(III)-reducing microorganisms to influence the formation of carbon and iron vector fluxes in ecosystems, as well as development of effective biotechnologies of water purification from iron compounds.

  7. Structural, electronic and magnetic properties of Fe{sub 2}-based full Heusler alloys: A first principle study

    Energy Technology Data Exchange (ETDEWEB)

    Dahmane, F., E-mail: fethallah05@gmail.com [Département de SM, Institue des sciences et des technologies, Centre universitaire de Tissemsilt, 38000, Tissemsilt (Algeria); Modelling and Simulation in Materials Science Laboratory, Physics Department, University of Sidi Bel-Abbes, 22000 Sidi Bel-Abbes (Algeria); Mogulkoc, Y. [Department of Engineering Physics, Ankara University, Ankara (Turkey); Doumi, B.; Tadjer, A. [Modelling and Simulation in Materials Science Laboratory, Physics Department, University of Sidi Bel-Abbes, 22000 Sidi Bel-Abbes (Algeria); Khenata, R. [Laboratoire de Physique Quantique de la Matière et de Modélisation Mathématique (LPQ3M), Université de Mascara, 29000 Mascara (Algeria); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O Box 2455, Riyadh 11451 (Saudi Arabia); Rai, D.P. [Department of Physics, Pachhunga University College, Aizawl-796001 (India); Murtaza, G. [Materials Modeling Lab, Department of Physics, Islamia College University, Peshawar (Pakistan); Varshney, Dinesh [Materials Science Laboratory, School of Physics, Vigyan Bhavan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India)

    2016-06-01

    Using the first-principles density functional calculations, the structural, electronic and magnetic properties of the Fe{sub 2}XAl (X=Cr, Mn, Ni) compounds in both the Hg{sub 2}CuTi and Cu{sub 2}MnAl-type structures were studied by the full-potential linearized augmented plane waves (FP-LAPW) method. The exchange and correlation potential is treated by the generalized-gradient approximation (GGA) where the results show that the Cu{sub 2}MnAl-type structure is energetically more stable than the Hg{sub 2}CuTi-type structure for the Fe{sub 2}CrAl and Fe{sub 2}MnAl compounds at the equilibrium volume. The full Heusler compounds Fe{sub 2}XAl (X=Cr, Mn) are half-metallic in the Cu{sub 2}MnAl-type structure. Fe{sub 2}NiAl has a metallic character in both CuHg{sub 2}Ti and AlCu{sub 2}Mn-type structures. The total magnetic moments of the Fe{sub 2}CrAl and Fe{sub 2}MnAl compounds are 1.0 and 2.0 μ{sub B}, respectively, which are in agreement with the Slater–Pauling rule M{sub tot}=Z{sub tot}− 24.

  8. Effect of Fe on the formation and H-sorption properties of Mg2FeH6

    Energy Technology Data Exchange (ETDEWEB)

    Asselli, A. A.C. [Universidade Federal de Sao Carlos (UFSCar), Sao Carlos, SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais; Ishikawa, T.T.; Neves, W.R.; Kiminami, C.S.; Botta, W.J. [Universidade Federal de Sao Carlos (UFSCar), Sao Carlos, SP (Brazil). Departamento de Engenharia de Materiais

    2009-07-01

    Full text: The compound Mg- - - -2- -FeH6- - - - was synthesized from a 2Mg+Fe mixture in a single process by reactive milling (RM) under hydrogen atmosphere at room temperature. The complex hydride was prepared from Mg powder and granulated (1-2 mm) or powdered Fe using a planetary mill. The phase evolution during different milling times (from 3 to 72h) was investigated by X-ray diffraction (XRD) technique. The dehydrogenation behavior of the so-formed metal hydride was investigated by differential scanning calorimetry (DSC). The use of powdered iron as starting material promoted conversion to complex hydride at shorter milling times than when granulated iron was used. On the other hand, the DSC analysis show a decrease in temperature of release of hydrogen for the as-milled 2Mg+Fe (Fe granulated) mixtures. Scanning (SEM) and transmission electron microscopy (TEM) have been carried out to correlate the structural characteristics of the as-milled materials to the decomposition behaviors. (author)

  9. Solid phase extraction of magnetic carbon doped Fe3O4 nanoparticles.

    Science.gov (United States)

    Yang, Jing; Li, Jia-yuan; Qiao, Jun-qin; Lian, Hong-zhen; Chen, Hong-yuan

    2014-01-17

    Carbon decorated Fe3O4 nanoparticles (Fe3O4/C) are promising magnetic solid-phase extraction (MSPE) sorbents in environmental and biological analysis. Fe3O4/C based MSPE method shows advantages of easy operation, rapidness, high sensitivity, and environmental friendliness. In this paper, the MSPE mechanism of Fe3O4/C nanoparticles has been comprehensively investigated, for the first time, through the following three efforts: (1) the comparison of extraction efficiency for polycyclic aromatic hydrocarbons (PAHs) between the Fe3O4/C sorbents and activated carbon; (2) the chromatographic retention behaviors of hydrophobic and hydrophilic compounds on Fe3O4/C nanoparticles as stationary phase; (3) related MSPE experiments for several typical compounds such as pyrene, naphthalene, benzene, phenol, resorcinol, anisole and thioanisole. It can be concluded that there are hybrid hydrophobic interaction and hydrogen bonding interaction or dipole-dipole attraction between Fe3O4/C sorbents and analytes. It is the existence of carbon and oxygen-containing functional groups coated on the surface of Fe3O4/C nanoparticles that is responsible for the effective extraction process. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Superconducting instabilities and quasipartical interference in the LiFeAs and Co-doped NaFeAs iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Altenfeld, Dustin; Ahn, Felix; Eremin, Ilya [Institut fuer Theoretische Physik III, Ruhr-Universitaet Bochum, D-44801 Bochum (Germany); Borisenko, Sergey [Leibniz-Institute for Solid State Research, IFW-Dresden, D-01171 Dresden (Germany)

    2015-07-01

    We analyze and compare the structure of the pairing interaction and superconducting gaps in LiFeAs and Co-doped NaFeAs by using the ten-orbital tight-binding model, derived from ab initio LDA calculations with hopping parameters extracted from the fit to ARPES experiments. We discuss the phase diagram and experimental probes to determine the structure of the superconducting gap in these systems with special emphasis on the quasiparticle interference, computed using the T-matrix approximation. In particular, we analyze how the superconducting state with opposite sign of the gaps on the two inner hole pockets in LiFeAs evolve upon changing the parameters towards NaFeAs compound.

  11. Curie temperature rising by fluorination for Sm2Fe17

    Directory of Open Access Journals (Sweden)

    Matahiro Komuro

    2013-02-01

    Full Text Available Fluorine atoms can be introduced to Sm2Fe17 using XeF2 below 423 K. The resulting fluorinated Sm2Fe17 powders have ferromagnetic phases containing Sm2Fe17FY1(0Fe17FY2 (1Fe17, and α-Fe. The unit cell for Sm2Fe17 is elongated by the fluorination. The largest unit cell volume among the rhombohedral Sm2Fe17 compounds is 83.8 nm3, which is 5.8% larger than Sm2Fe17. The rhombohedral Sm2Fe17 with the largest unit cell volume is dissociated above 873 K, and fluorination increases Curie temperature from 403 K for Sm2Fe17 to 675 K. This increase can be explained by the magneto-volume effect.

  12. Magnetism and electronic structure of CoFeCrX (X = Si, Ge) Heusler alloys

    International Nuclear Information System (INIS)

    Jin, Y.; O'Connell, A.; Kharel, P.; Lukashev, P.; Staten, B.; Tutic, I.; Valloppilly, S.; Herran, J.; Mitrakumar, M.; Bhusal, B.; Huh, Y.; Yang, K.; Skomski, R.; Sellmyer, D. J.

    2016-01-01

    The structural, electronic, and magnetic properties of CoFeCrX (X = Si, Ge) Heusler alloys have been investigated. Experimentally, the alloys were synthesized in the cubic L2 1 structure with small disorder. The cubic phase of CoFeCrSi was found to be highly stable against heat treatment, but CoFeCrGe disintegrated into other new compounds when the temperature reached 402 °C (675 K). Although the first-principle calculation predicted the possibility of tetragonal phase in CoFeCrGe, the tetragonal phase could not be stabilized experimentally. Both CoFeCrSi and CoFeCrGe compounds showed ferrimagnetic spin order at room temperature and have Curie temperatures (T C ) significantly above room temperature. The measured T C for CoFeCrSi is 790 K but that of CoFeCrGe could not be measured due to its dissociation into new compounds at 675 K. The saturation magnetizations of CoFeCrSi and CoFeCrGe are 2.82 μ B /f.u. and 2.78 μ B /f.u., respectively, which are close to the theoretically predicted value of 3 μ B /f.u. for their half-metallic phases. The calculated band gaps for CoFeCrSi and CoFeCrGe are, respectively, 1 eV and 0.5 eV. These materials have potential for spintronic device applications, as they exhibit half-metallic electronic structures with large band gaps, and Curie temperatures significantly above room temperature.

  13. Disappearance of superconductivity in the solid solution between (Ca4Al2O6)(Fe2As2) and (Ca4Al2O6)(Fe2P2) superconductors.

    Science.gov (United States)

    Shirage, Parasharam M; Kihou, Kunihiro; Lee, Chul-Ho; Takeshita, Nao; Eisaki, Hiroshi; Iyo, Akira

    2012-09-19

    The effect of alloying the two perovskite-type iron-based superconductors (Ca(4)Al(2)O(6))(Fe(2)As(2)) and (Ca(4)Al(2)O(6))(Fe(2)P(2)) was examined. While the two stoichiometric compounds possess relatively high T(c)'s of 28 and 17 K, respectively, their solid solutions of the form (Ca(4)Al(2)O(6))(Fe(2)(As(1-x)P(x))(2)) do not show superconductivity over a wide range from x = 0.50 to 0.95. The resultant phase diagram is thus completely different from those of other typical iron-based superconductors such as BaFe(2)(As,P)(2) and LaFe(As,P)O, in which superconductivity shows up when P is substituted for As in the non-superconducting "parent" compounds. Notably, the solid solutions in the non-superconducting range exhibit resistivity anomalies at temperatures of 50-100 K. The behavior is reminiscent of the resistivity kink commonly observed in various non-superconducting parent compounds that signals the onset of antiferromagnetic/orthorhombic long-range order. The similarity suggests that the suppression of the superconductivity in the present case also has a magnetic and/or structural origin.

  14. RbCuFe(PO42

    Directory of Open Access Journals (Sweden)

    Mongi Ben Amara

    2013-08-01

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

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

    Science.gov (United States)

    Fabrizi, A.; Timelli, G.

    2016-03-01

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

  16. Magnetocrystalline anisotropy constants, rotational hysteresis energy and magnetic domain structure in UFe6Al6, UFe9AlSi2 and ScFe10Si2 intermetallic compounds

    International Nuclear Information System (INIS)

    Wyslocki, J.J.; Pawlik, P.; Wochowski, K.; Kotur, B.; Bodak, O.I.

    1996-01-01

    The magnetic torque, T, was applied to determine the anisotropy constants K 1 and K 2 of the UFe 6 Al 6 , UFe 9 AlSi 2 and ScFe 10 Si 2 compounds. The mechanism of magnetization reversal processes in these compounds was investigated on the basis of the analysis of the rotational hysteresis energy, W r and rotational hysteresis integral, R, calculated from the magnetic torque curves. Applying the powder pattern method, magnetic domain structures were observed. Moreover, the fundamental parameters of the domain structure were determined. (orig.)

  17. Browse Title Index

    African Journals Online (AJOL)

    2004): Special Issue 2004, Differential production of immune parameters by mouse strains ... agglutination and complement fixation tests in the field diagnosis ... List All Titles · Free To Read Titles This Journal is Open Access.

  18. Moessbauer spectroscopic studies of the chemical effects associated with 57Co(electron capture)57Fe decay in tris-β-diketonatocobalt(III) compounds

    International Nuclear Information System (INIS)

    Sakai, Yoichi; Endo, Kazutoyo; Sano, Hirotoshi

    1980-01-01

    Magnetic hyperfine structures (hfs) were found in the absorption Moessbauer spectra at 78 K of a paramagnetic iron(III) complex diluted in a diamagnetic cobalt(III) or aluminium(III) complex such as 57 Fe(acac) 3 in Co(acac) 3 , 57 Fe(oxin) 3 in Al(oxin) 3 , and 57 Fe(dbm) 3 in Co(dbm) 3 (acac=acetylacetonato, oxin=8-quinolinolato, and dbm=dibenzoylmethanato), showing that the magnetic hfs is caused by the spin-spin relaxation through the surrounding diamagnetic species. In the emission Moessbauer experiments, magnetic hfs was observed at 78 K in 57 Co-labelled Co(dbm) 3 , Co(oxin) 3 , and polystyrene-diluted Co(acac) 3 , while it was not observed in 57 Co-labelled Co(acac) 3 and Co(dpm) 3 (dpm=dipivaloylmethanato). The former possess pi -conjugated systems to a greater extent than the latter, either in the ligands or in the vicinity of the 57 Co-labelled Co(III) species. These results were explained in terms of the radiolytic stabilities of the matrices as well as those of 57 Co-labelled compounds by showing that the paramagnetic radicals produced in a diamagnetic matrix quench the magnetic hfs because of the increased spin-spin interaction, as a consequence of the local radiolysis by EC-decay. (author)

  19. Amorphous NiFe-OH/NiFeP Electrocatalyst Fabricated at Low Temperature for Water Oxidation Applications

    KAUST Repository

    Liang, Hanfeng

    2017-04-11

    Water splitting driven by electricity or sunlight is one of the most promising ways to address the global terawatt energy needs of future societies; however, its large-scale application is limited by the sluggish kinetics of the oxygen evolution reaction (OER). NiFe-based compounds, mainly oxides and hydroxides, are well-known OER catalysts and have been intensively studied; however, the utilization of the synergistic effect between two different NiFe-based materials to further boost the OER performance has not been achieved to date. Here, we report the rapid conversion of NiFe double hydroxide into metallic NiFeP using PH3 plasma treatment and further construction of amorphous NiFe hydroxide/NiFeP/Ni foam as efficient and stable oxygen-evolving anodes. The strong electronic interactions between NiFe hydroxide and NiFeP significantly lower the adsorption energy of H2O on the hybrid and thus lead to enhanced OER performance. As a result, the hybrid catalyst can deliver a geometrical current density of 300 mA cm–2 at an extremely low overpotential (258 mV, after ohmic-drop correction), along with a small Tafel slope of 39 mV decade–1 and outstanding long-term durability in alkaline media.

  20. NMR and XAS Study of Fe-Mo Double Perovskites

    International Nuclear Information System (INIS)

    Zajac, D.A.; Kapusta, C.; Borowiec, M.; Sikora, M.; Marquina, C.; Blasco, J.; Ibarra, M.R.

    2005-01-01

    The results of NMR and XAS measurements of the A 2 FeMoO 6 double perovskites (DP) (A 2 =Sr 2 , SrBa, Ba 2 , Ca 2 ) at the Fe and Mo K edges are reported and the information on the individual site electronic and magnetic properties is analysed. The compounds studied belong to the family of materials exhibiting a high field '' colossal '' magnetoresistance as well as a low field '' giant '' magnetoresistance. Magnetoresistive properties of the compounds arise from their half-metallicity, i.e. only one spin direction being populated in the conduction band, which consists of overlapping spin down 3d Fe, 2p O and 4d Mo electron bands. Within the model, a spin-down electron undergoes a fast hopping through unoccupied oxygen 2p orbitals between Fe 3+ (3d 5 - spin up) and Mo 6+ (4d 0 ) ionic cores. This mechanism implicates an anti-parallel coupling of the Fe and Mo spins and leads to non-integer magnetic moments and a metallic character below TC. The interaction, in analogy with the '' double exchange '' (DE) in manganites, is called '' double exchange-like '' interaction. The superexchange interaction (SE) is also expected to be present, resulting also in an anti-parallel coupling of 3d Fe 3+ and 4d Mo 5+ spins through occupied oxygen 2p orbitals. The insulating character of SE is connected with an increase of the tilt angle of the Fe-O-Mo bond, which is related to a change of the structural tolerance factor f and results in structural distortions. The molybdenum NMR measurements revealed the existence of a non-integer magnetic moment at Mo and Fe, which can be attributed to the DE-like interaction. However, experiments using Moessbauer spectroscopy have shown the existence of two Fe ionisation states - with integer (SE) and non integer (DE) magnetic moments. The 95 Mo and 97 Mo NMR measurements on A 2 FeMoO 6 (A 2 =Sr 2 , SrBa, Ba 2 , Ca 2 ) presented in this work show different values of the Mo hyperfine field and the corresponding magnetic moment. This is attributed

  1. Solid-state phase equilibria in the Fe-Pt-Pr ternary system at 1173 K

    International Nuclear Information System (INIS)

    Ren Jing; Gu Zhengfei; Cheng Gang; Zhou Huaiying

    2005-01-01

    The solid-state phase equilibria in the Fe-Pt-Pr ternary system at 1173 K (Pr ≤ 70%) were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. The 1173 K isothermal section consists of 13 single-phase regions, 22 two-phase regions and 10 three-phase regions. At 1173 K, we have observed that the maximum solid solubility of Pt in α-Fe is below 1.5 at.% and the solid solution region of Pt in γ-Fe is from 2 to 35 at.%; the maximum solid solubility of Fe in Pt is 18 at.%. The maximum solubility of Fe in PrPt 5 , PrPt 3 , PrPt 2 , Pr 3 Pt 4 , PrPt, Pr 3 Pt 2 and Pr 7 Pt 3 is below 1 at.%. The maximum solubility of Pr in α-(Fe, Pt), γ-(Fe, Pt), FePt, FePt 3 and (Pt, Fe) (the solid solution of Fe in Pt) is 6, 2, 4, 4.5 and 1.5 at.%, respectively. In this work, it is found that the phase Pr 3 Pt 4 does not exist in the ternary system. The binary compounds Fe 7 Pr and Fe 2 Pr and any new ternary compounds were not observed

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

    International Nuclear Information System (INIS)

    Fabrizi, A; Timelli, G

    2016-01-01

    This study investigates the morphological evolution of primary α-Al(Fe,Mn,Cr)Si phase in a secondary Al-Si-Cu alloy with respect to the initial Fe and Cr contents as well as to the cooling rate. The solidification experiments have been designed in order to cover a wide range of cooling rates, and the Fe and Cr contents have been varied over two levels. Metallographic and image analysis techniques have been used to quantitatively examine the microstructural changes occurring at different experimental conditions. The morphological evolution of the α-Fe phase has been also analysed by observing deep etched samples. By changing the cooling rate, α-Al 15 (Fe,Mn,Cr) 3 Si 2 dodecahedron crystals, as well as Chinese- script, branched structures and dendrites form, while primary coarse β-Al 5 (Fe,Mn)Si needles appear in the alloy with the highest Fe content at low cooling rates. (paper)

  3. Determination of localized Fe2+/Fe3+ ratios in inks of historic documents by means of μ-XANES

    International Nuclear Information System (INIS)

    Proost, K.; Janssens, K.; Wagner, B.; Bulska, E.; Schreiner, M.

    2004-01-01

    An important part of the European cultural heritage is composed of hand-written documents. Many of these documents were drawn up with iron-gall ink. This type of ink present a serious conservation problem, as it slowly oxidizes ('burns') the paper it is written on, thereby gradually disintegrating the historic document. Acid hydrolysis of the cellulose and/or the oxidation of organic compounds promoted by radical intermediates that are formed due to the presence of Fe 2+ ions are considered to be the cause of the disintegration. μ-XANES measurements were performed with a lateral resolution of 30-50 μm in order to determine the local Fe 2+ /Fe 3+ ratio in 19th C. documents from the Austrian National Archives and fragments of 16th C documents from the Polish National Library. In the 19th C documents, no significant amount of Fe 2+ was detected. On the other hand, in the 16th C fragments, significant amounts of Fe 2+ and appreciable differences in distribution of Fe 2+ and Fe 3+ within individual letters/ink stains were observed

  4. CoFeRh alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tabakovic, Ibro [Seagate Technology, Research and Development, Bloomington, MN 55435 (United States)], E-mail: ibro.m.tabakovic@seagate.com; Qiu Jiaoming; Riemer, Steve; Sun Ming; Vas' ko, Vlad; Kief, Mark [Seagate Technology, Research and Development, Bloomington, MN 55435 (United States)

    2008-01-01

    The electrochemical behavior of Rh(III) species in CoFe solution containing RhCl{sub 3}, NH{sub 4}Cl, H{sub 3}BO{sub 3}, CoSO{sub 4}, FeSO{sub 4}, saccharin, and NaLS (Na lauryl sulfate) has been investigated. The electrochemistry of Rh(III) species is influenced by each of the compounds present in CoFe plating solution, but especially by addition of saccharin and H{sub 3}BO{sub 3} to the RhCl{sub 3}-NH{sub 4}Cl solution. The nucleation and growth of Rh on GC (glassy carbon), Ru, and Cu electrodes from NH{sub 4}Cl solution was studied using the potentiostatic current-transient methods. The results support a predominantly progressive nucleation of Rh on all three-electrode surfaces. The nucleation kinetic parameters ANo (steady state nucleation rate) and Ns (saturation nuclear number density) were found to vary with potential and are electrode-dependent in order: GC > Ru{approx}Cu. The electrodeposited Rh films obtained from NH{sub 4}Cl solution and nonmagnetic CoFeRh film obtained from CoFe solution were characterized in terms of the following properties: morphology, surface roughness, crystal structure and chemical composition. The origin of light elements found in Rh and CoFeRh films (O, Cl, S, C, N) was discussed.

  5. Experimental determination of the phase equilibria in the Co-Fe-Zr ternary system

    International Nuclear Information System (INIS)

    Wang, C.P.; Yu, Y.; Zhang, H.H.; Hu, H.F.; Liu, X.J.

    2011-01-01

    Research highlights: → We determined four isothermal sections of the Co-Fe-Zr system from 1000 o C to 1300 o C. → No ternary compound was found in the Co-Fe-Zr ternary system. → The solubility of Fe in the liquid phase at 1300 o C is extremely large. → The (Co, Fe) 2 Zr phase form the continuous solution from Co-Zr side to Fe-Zr side. → The solubility of Zr in the fcc (Co, Fe) phase is extremely small. - Abstract: The phase equilibria in the Co-Fe-Zr ternary system were investigated by means of optical microscopy (OM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) on equilibrated ternary alloys. Four isothermal sections of the Co-Fe-Zr ternary system at 1300 o C, 1200 o C, 1100 o C and 1000 o C were experimentally established. The experimental results indicate that (1) no ternary compound was found in this system; (2) the solubility of Fe in the liquid phase of the Co-rich corner at 1300 o C is extremely large; (3) the liquid phase in the Zr-rich corner and the (Co,Fe) 2 Zr phase form the continuous solid solutions from the Co-Zr side to the Fe-Zr side; (4) the solubility of Zr in the fcc (Co, Fe) phase is extremely small.

  6. Fe-Impregnated Mineral Colloids for Peroxide Activation: Effects of Mineral Substrate and Fe Precursor.

    Science.gov (United States)

    Li, Yue; Machala, Libor; Yan, Weile

    2016-02-02

    Heterogeneous iron species at the mineral/water interface are important catalysts for the generation of reactive oxygen species at circumneutral pH. One significant pathway leading to the formation of such species arises from deposition of dissolved iron onto mineral colloids due to changes in redox conditions. This study investigates the catalytic properties of Fe impregnated on silica, alumina, and titania nanoparticles (as prototypical mineral colloids). Fe impregnation was carried out by immersing the mineral nanoparticles in dilute Fe(II) or Fe(III) solutions at pH 6 and 3, respectively, in an aerobic environment. The uptake of iron per unit surface area follows the order of nTiO2 > nAl2O3 > nSiO2 for both types of Fe precursors. Impregnation of mineral particles in Fe(II) solutions results in predominantly Fe(III) species due to efficient surface-mediated oxidation. The catalytic activity of the impregnated solids to produce hydroxyl radical (·OH) from H2O2 decomposition was evaluated using benzoic acid as a probe compound under dark conditions. Invariably, the rates of benzoic acid oxidation with different Fe-laden particles increase with the surface density of Fe until a critical density above which the catalytic activity approaches a plateau, suggesting active Fe species are formed predominantly at low surface loadings. The critical surface density of Fe varies with the mineral substrate as well as the aqueous Fe precursor. Fe impregnated on TiO2 exhibits markedly higher activity than its Al2O3 and SiO2 counterparts. The speciation of interfacial Fe is analyzed with diffuse reflectance UV-vis analysis and interpretation of the data in the context of benzoic oxidation rates suggests that the surface activity of the solids for ·OH generation correlates strongly with the isolated (i.e., mononuclear) Fe species. Therefore, iron dispersed on mineral colloids is a significant form of reactive iron surfaces in the aquatic environment.

  7. Study of 5f electron based filled skutterudite compound EuFe{sub 4}Sb{sub 12}, a thermoelectric (TE) material: FP-LAPW method

    Energy Technology Data Exchange (ETDEWEB)

    Shankar, A., E-mail: amitshan2009@gmail.com [Department of Physics, Mizoram University, Aizawl 796004 (India); Rai, D.P., E-mail: dibyaprakashrai@gmail.com [Beijing Computational Science Research Center, 3 Heqing Road, Beijing 100084 (China); Khenata, R. [Laboratoire de Physique Quantique et de Modlisation Mathmatique (LPQ3M), Dpartement de Technologie, Universit de Mascara, 29000 Mascara (Algeria); Maibam, J. [Department of Physics, Assam University, Silchar 788011 (India); Sandeep, E-mail: sndp.chettri@gmail.com [Department of Physics, Mizoram University, Aizawl 796004 (India); Thapa, R.K., E-mail: r.k.thapa@gmail.com [Department of Physics, Mizoram University, Aizawl 796004 (India)

    2015-01-15

    Highlights: • The compound EuFe{sub 4}Sb{sub 12} shows a semi-metallic behavior with pseudo gap. • The inherent dense band near E{sub F} facilitate the charge carriers. • The magnetic moment within LSDA and mBJ are underestimated. • The inclusion of onsite Coulomb repulsion (U) in LSDA has improved the result. • The results obtained from LSDA + U are consistent with the experimental data. - Abstract: We have studied the elastic, electronic and magnetic properties along with the thermoelectric properties of an undoped filled skutterudite EuFe{sub 4}Sb{sub 12} using full-potential linearized augmented plane wave (FP-LAPW) method. The LSDA, LSDA + U and a new exchange-correlation functional called modified Becke Johnson (mBJ) potential based on density functional theory (DFT) were used for studying material properties. The Eu-f and Fe-d are strongly correlated elements thus the inclusion of Coulomb repulsion (U) expected to give an exact ground state properties. The exchange-splitting of Eu-4f states were analyzed to explain the ferromagnetic behavior of EuFe{sub 4}Sb{sub 12} (half-metallic behavior). The numerical values of isotropic elastic parameters and related properties are estimated in the framework of the Voigt–Reuss–Hill approximation. The calculation of thermal transport properties at various temperature shows the high value of Seebeck coefficient and figure of merit (ZT) = 0.25 at room temperature in consistent to the experimental results.

  8. The Fe-Cr-Zn system in relation with the galvanizing process in chromium-added zinc bath

    Energy Technology Data Exchange (ETDEWEB)

    Reumont, G.; Mathon, M.; Fourmentin, R.; Perrot, P. [LMPGM, UMR CNRS 8517, Univ. de Lille I, Villeneuve d' Ascq (France)

    2003-04-01

    Taking into account new experimental measurements, the Fe-Zn-Cr ternary system is critically modified at 460 C. A continuous solid solution between {zeta}-FeZn{sub 13} and CrZn{sub 13} compounds is shown but is shared at 460 C by the stable CrZn{sub 17} compound containing about 2 wt.% Fe. This ternary system is assessed with the CALPHAD method using the PARROT modulus of the Thermo-Calc software. The liquid and solid solution phases are modeled with Redlich-Kister-Muggianu equations. The intermetallic compounds {zeta}-(Fe,Cr)Zn{sub 13} and CrZn{sub 17} are treated as stoichiometric compounds in the binary systems. The experimental Fe and Cr solubilities at various temperatures modify the shape of the liquidus curve and are satisfying for industrial applications. A set of parameters consistent with most of the available experimental data on both phase diagram and solubility measurements is obtained by optimization. A comparison with previous experimental work is also presented and a reactional model between iron substrate and Zn-Cr bath is proposed. This optimization allows to interpret the growth of intermetallic layers and the formation of dross when galvanizing in Cr-added Zn bath. (orig.)

  9. In situ X-ray and neutron diffraction of the Ruddlesden-Popper compounds (RE2-xSrx)0.98(Fe0.8Co0.2)1-yMgyO4-δ (RE=La, Pr): Structure and CO2 stability

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Hauback, B.C.; Hendriksen, Peter Vang

    2013-01-01

    The crystal structure of the Ruddlesden-Popper compounds (La 1.0Sr1.0)0.98Fe0.8Co 0.2O4-δ and (La1.2Sr0.8) 0.98(Fe0.8Co0.2)0.8Mg 0.2O4-δ was investigated at 1000 °C in N 2 (aO2=1×10-4) by in-situ powder neutron diffraction. In-situ powder X-ray diffraction (PXD) was also employed to investigate....... The equivalent pseudo-cubic thermal and chemical expansion coefficients are in agreement with values determined by dilatometry. The chemical stability in CO2 containing environments of various Ruddlesden-Popper compounds with chemical formula (RE2-xSr x)0.98(Fe0.8Co0.2) 1-yMgyO4-δ (RE=La, Pr), as well...

  10. INIS: Authority List for Journal Titles

    International Nuclear Information System (INIS)

    1992-01-01

    This is the nineteenth revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). It lists 10,797 journal titles which have contained articles within the scope of INIS. The purpose of this Authority List is to provide descriptive cataloguers with a standard abbreviation for journal titles and to assist users of INIS products with a tool for verifying the full title of a journal. A journal, or periodical, is generally published within a defined, fixed interval between issues, which usually has more than one issue a year, and which usually includes a mixture of articles, letters, summaries, etc. Within this definition, annuals such as Annual Review of Nuclear Science are included. Series titles as, for example the McGraw-Hill Series in Nuclear Engineering, are not included in this Authority. Entries: Each entry consists of: - the full journal title (highlighted); - the abbreviated title; - ISSN, if available; - CODEN, if available; - additional information related to the journal title. Arrangement: In Part I, the full journal titles are grouped by country or international organization name and ordered alphabetically, followed by the ISSN, the CODEN in square brackets if available, and then the abbreviated title. The abbreviated title is based on the rules of ISO 4: Documentation - International Code for the Abbreviation of Titles of Periodicals. The abbreviations of the words are taken from the ISDS List of Periodical Title Word Abbreviation. In Part II, the order of the citations is reversed: the abbreviated journal titles are arranged alphabetically, followed by country code. Then the full journal titles are followed by the country of publication, and if available, ISSN and CODEN. Additional Information: There is important information related to the journal titles which are fundamental for tracing the history of the title and the present status. They are listed below and are entered whenever applicable: - Ceased publication; - Superseded by

  11. Pengaruh Pemasaran Rasional, Emosional, Dan Spiritual Terhadap Keputusan Membeli Teh Botol Sosro Pada Mahasiswa FE USU

    OpenAIRE

    Lubis, Astria Amelia

    2012-01-01

    The title of this research is' Influence Marketing Rational, Emotional, and Spiritual Decision Against Buying Product Botol Sosro In FE USU Student ". The purpose of this research is to investigate and analyze the influence of marketing rational, emotional, and spiritual to the decision to buy products Botol Sosro on FE.USU student. The data used in this study is to use primary data and secondary data. Study sample of 53 respondents. Data analysis methods used is descriptive quantitative b...

  12. Title IX Resource Guide

    Science.gov (United States)

    Office for Civil Rights, US Department of Education, 2015

    2015-01-01

    Title IX of the Education Amendments of 1972 (Title IX) prohibits discrimination based on sex in education programs and activities in federally funded schools at all levels. If any part of a school district or college receives any Federal funds for any purpose, all of the operations of the district or college are covered by Title IX. The essence…

  13. Contribution to the study of magnetic properties of rare-earth iron intermetallic compounds

    International Nuclear Information System (INIS)

    Morariu, M.

    1976-01-01

    The intermetallic binary compounds Ysub(x)Fesub(y)(YFe 2 ,YFe 3 ,Y 6 Fe 23 ,Y 2 Fe 17 ), RFe 2 (R=Gd,Tb,Dy,Ho,Er and Tm) and the intermetallic pseudobinary compounds (Gdsub(x)Ysub(1-x))Fe 2 and Dy(Fesub(x)Nisub(1-x)) 3 were studied, using magnetic measurements and Moessbauer spectroscopy, in order to obtain information on their magnetic behaviour. The different models which describe magnetic interactions in rare-earths with 3d transition element compounds are reviewed. The magnetic hyperfine field Hsub(n) at the Fe 57 nucleus, measured by Moessbauer spectroscopy, depends on the atom position in the lattice, being sensitive to magnetic interactions with neighbouring atoms. The mean value of the magnetic hyperfine field, average Hsub(n) is proportional to the mean magnetic moment of the iron atom: average Hsub(n)/average μsub(Fe) approximately 150 kOe. The comparative study of the temperature dependence of average Hsub(n) and average μsub(Fe) values shows that this relation is valid for the whole range of magnetic ordering (T>Tsub(c)). The mean magnetic hyperfine fields at the Fe 57 nucleus in RFe 2 compounds depend on the rare-earth partner and vary approximative linearly with the Gennes factor. The spin reorientation diagram for the (Gdsub(x)Ysub(1-x))Fe 2 system is obtained. All results on Moessbauer spectroscopy are in good agreement with the magnetic measurements. The magnetic behaviour of iron atoms is justified using a model in which the most electrons are in a narrow band, so they could be considered localized, and the magnetic interactions between these atoms take place through a fraction (<5%) of 3d itinerant electrons. (author)

  14. Measurement of N and C diffusion in Sm2Fe17 by magnetic relaxation

    International Nuclear Information System (INIS)

    Mommer, N.; Hirscher, M.; Gerlach, M.; Van Lier, J.; Kronmueller, H.; Kubis, M.; Mueller, K.-H.

    1998-01-01

    Magnetic after-effect (MAE) measurements of nitrided and carburized Sm 2 Fe 17 compounds were performed in the temperature range of 140 K to 480 K. Both nitrided and carburized compounds show relaxation maxima at 285 and 300 K, respectively, which are absent in pure Sm 2 Fe 17 compounds. Therefore, these relaxation maxima are attributed to jumps of interstitially dissolved nitrogen or carbon atoms. Numerical evaluation yielded an activation enthalpy Q N (0.84±0.05) eV and a pre-exponential factor τ 0 N =3.10 -15±1 s for the short-range diffusion of N atoms. The corresponding values for the carbon diffusion are Q C =(0.91±0.05) eV and τ 0 C =1.10 -15±1 s. The carbon and nitrogen content of the samples was determined from the increase in mass during nitrogenation or carburization to Sm 2 Fe 17 N 1.2 and Sm 2 Fe 17 C 2.6 . (orig.)

  15. Getting to one from title 10 + title 32 unity of effort in the homeland

    OpenAIRE

    Prosch, Caroline Ross.

    2011-01-01

    CHDS State/Local Approved for public release; distribution is unlimited This thesis bridges the knowledge gap between Title 10 Active Duty and Title 32 National Guard in order to breakdown cultural barriers and reach unity of effort for response operations in the homeland. Regrettably, a unified response was missing among Title 10 Active Duty and Title 32 National Guard members following Hurricane Katrina. Since then, initiatives based in doctrine, statutes and formal recommendations...

  16. Induction of apoptosis by Fe(salenCl through caspase-dependent pathway specifically in tumor cells

    Directory of Open Access Journals (Sweden)

    Nitika Pradhan

    2017-10-01

    Full Text Available Iron-based compounds possess the capability of inducing cell death due to their reactivity with oxidant molecules, but their specificity towards cancer cells and the mechanism of action are hitherto less investigated. A Fe(salenCl derivative has been synthesized that remains active in monomer form. The efficacy of this compound as an anti-tumor agent has been investigated in mouse and human leukemia cell lines. Fe(salenCl induces cell death specifically in tumor cells and not in primary cells. Mouse and human T-cell leukemia cell lines, EL4 and Jurkat cells are found to be susceptible to Fe(salenCl and undergo apoptosis, but normal mouse spleen cells and human peripheral blood mononuclear cells (PBMC remain largely unaffected by Fe(salenCl. Fe(salenCl treated tumor cells show significantly higher expression level of cytochrome c that might have triggered the cascade of reactions leading to apoptosis in cancer cells. A significant loss of mitochondrial membrane potential upon Fe(salenCl treatment suggests that Fe(salenCl induces apoptosis by disrupting mitochondrial membrane potential and homeostasis, leading to cytotoxity. We also established that apoptosis in the Fe(salenCl-treated tumor cells is mediated through caspase-dependent pathway. This is the first report demonstrating that Fe(salenCl can specifically target the tumor cells, leaving the primary cells least affected, indicating an excellent potential for this compound to emerge as a next-generation anti-tumor drug.

  17. Induction of apoptosis by Fe(salen)Cl through caspase-dependent pathway specifically in tumor cells.

    Science.gov (United States)

    Pradhan, Nitika; Pratheek, B M; Garai, Antara; Kumar, Ashutosh; Meena, Vikram S; Ghosh, Shyamasree; Singh, Sujay; Kumari, Shikha; Chandrashekar, T K; Goswami, Chandan; Chattopadhyay, Subhasis; Kar, Sanjib; Maiti, Prasanta K

    2014-10-01

    Iron-based compounds possess the capability of inducing cell death due to their reactivity with oxidant molecules, but their specificity towards cancer cells and the mechanism of action are hitherto less investigated. A Fe(salen)Cl derivative has been synthesized that remains active in monomer form. The efficacy of this compound as an anti-tumor agent has been investigated in mouse and human leukemia cell lines. Fe(salen)Cl induces cell death specifically in tumor cells and not in primary cells. Mouse and human T-cell leukemia cell lines, EL4 and Jurkat cells are found to be susceptible to Fe(salen)Cl and undergo apoptosis, but normal mouse spleen cells and human peripheral blood mononuclear cells (PBMC) remain largely unaffected by Fe(salen)Cl. Fe(salen)Cl treated tumor cells show significantly higher expression level of cytochrome c that might have triggered the cascade of reactions leading to apoptosis in cancer cells. A significant loss of mitochondrial membrane potential upon Fe(salen)Cl treatment suggests that Fe(salen)Cl induces apoptosis by disrupting mitochondrial membrane potential and homeostasis, leading to cytotoxity. We also established that apoptosis in the Fe(salen)Cl-treated tumor cells is mediated through caspase-dependent pathway. This is the first report demonstrating that Fe(salen)Cl can specifically target the tumor cells, leaving the primary cells least affected, indicating an excellent potential for this compound to emerge as a next-generation anti-tumor drug. © 2014 International Federation for Cell Biology.

  18. Browse Title Index

    African Journals Online (AJOL)

    Items 601 - 650 of 788 ... Browse Title Index ... Issue, Title ... Vol 14, No 1 (2006), Social science research: a critique of quantitative and qualitative methods ... Vol 18, No 1 (2010), Stress among part-time business students: a study in a Ghanaian ...

  19. Magnetic properties of the Ce2Fe17-x Mn x helical magnets up to high magnetic fields

    International Nuclear Information System (INIS)

    Kuchin, A.G.; Mushnikov, N.V.; Bartashevich, M.I.; Prokhnenko, O.; Khrabrov, V.I.; Lapina, T.P.

    2007-01-01

    Magnetic properties of the Ce 2 Fe 17- x Mn x , x=0-2, alloys in magnetic fields up to 40 T are reported. The compounds with x=0.5-1 are helical antiferromagnets and those with 1 B that couple antiparallelly to the Fe moments. Easy-plane magnetic anisotropy in the Ce 2 Fe 17- x Mn x compounds weakens upon substitution of Mn for Fe. The absolute value of the first anisotropy constant in the Ce 2 Fe 17- x Mn x helical ferromagnets decreases slower with increasing temperature than that calculated from the third power of the spontaneous magnetization. Noticeable magnetic hysteresis in the Ce 2 Fe 17- x Mn x , x=0.5-2, helical magnets over the whole range of magnetic fields reflects mainly irreversible deformation of the helical magnetic structure during the magnetization of the compounds. A contribution from short-range order (SRO) magnetic clusters to the magnetic hysteresis of the helical magnets has been also estimated

  20. 20 CFR 408.931 - How much will we withhold from your title II and title XVI benefits to recover a title VIII...

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false How much will we withhold from your title II... and Overpayments Adjustment of Title II Benefits § 408.931 How much will we withhold from your title...-due benefits. (b)(1) We will collect the overpayment from current monthly benefits due in a month...

  1. Human Intestinal Fluid Layer Separation: The Effect On Colloidal Structures & Solubility Of Lipophilic Compounds.

    Science.gov (United States)

    Danny, Riethorst; Amitava, Mitra; Filippos, Kesisoglou; Wei, Xu; Jan, Tack; Joachim, Brouwers; Patrick, Augustijns

    2018-05-23

    In addition to individual intestinal fluid components, colloidal structures are responsible for enhancing the solubility of lipophilic compounds. The present study investigated the link between as well as the variability in the ultrastructure of fed state human intestinal fluids (FeHIF) and their solubilizing capacity for lipophilic compounds. For this purpose, FeHIF samples from 10 healthy volunteers with known composition and ultrastructure were used to determine the solubility of four lipophilic compounds. In light of the focus on solubility and ultrastructure, the study carefully considered the methodology of solubility determination in relation to colloid composition and solubilizing capacity of FeHIF. To determine the solubilizing capacity of human and simulated intestinal fluids, the samples were saturated with the compound of interest, shaken for 24 h, and centrifuged. When using FeHIF, solubilities were determined in the micellar layer of FeHIF, i.e. after removing the upper (lipid) layer (standard procedure), as well as in 'full' FeHIF (without removal of the upper layer). Compound concentrations were determined using HPLC-UV/fluorescence. To link the solubilizing capacity with the ultrastructure, all human and simulated fluids were imaged using transmission electron microscopy (TEM) before and after centrifugation and top layer (lipid) removal. Comparing the ultrastructure and solubilizing capacity of individual FeHIF samples demonstrated a high intersubject variability in postprandial intestinal conditions. Imaging of FeHIF after removal of the upper layer clearly showed that only micellar structures remain in the lower layer. This observation suggests that larger colloids such as vesicles and lipid droplets are contained in the upper, lipid layer. The solubilizing capacity of most FeHIF samples substantially increased with inclusion of this lipid layer. The relative increase in solubilizing capacity upon inclusion of the lipid layer was most pronounced

  2. Browse Title Index

    African Journals Online (AJOL)

    Items 151 - 200 of 229 ... Browse Title Index ... Issue, Title. Vol 14, No 2 ... Vol 15, No 1 (2017), Qualitative and quantitative methods of suicide research in old age, Abstract PDF ... Vol 11, No 2 (2013), Simple Algorithm in the Management of Fetal ...

  3. Superconductivity induced by doping Rh in CaFe2-xRhxAs2

    International Nuclear Information System (INIS)

    Qi Yanpeng; Wang Lei; Gao Zhaoshun; Wang Dongliang; Zhang Xianping; Wang Chunlei; Yao Chao; Ma Yanwei

    2011-01-01

    In this paper, we report the synthesis of iron-based superconductors CaFe 2-x Rh x As 2 using a one-step solid state reaction method that crystallizes in the ThCr 2 Si 2 -type structure with a space group I4/mmm. The systematic evolution of the lattice constants demonstrates that the Fe ions are successfully replaced by the Rh. By increasing the doping content of Rh, the spin-density-wave (SDW) transition in the parent compound is suppressed and superconductivity emerges. The maximum superconducting transition temperature is found at 18.5 K with a doping level of x=0.15. The temperature dependence of dc magnetization confirms superconducting transitions at around 15 K. The general phase diagram was obtained and found to be similar to the case of the Rh-doping Sr122 system. Our results explicitly demonstrate the feasibility of inducing superconductivity in Ca122 compounds by higher d-orbital electron doping; however, different Rh-doping effects between FeAs122 compounds and FeAs1111 systems still remains an open question.

  4. Moessbauer study of (Fe1-x Cu x )4N (0.05≤x≤0.15) films

    International Nuclear Information System (INIS)

    El Khiraoui, S.; Sajieddine, M.; Vergnat, M.; Bauer, Ph.; Mabrouki, M.

    2007-01-01

    In this work, we have prepared nitrogenated Fe 1- x Cu x alloys by reactive evaporation under a flow of nitrogen ions. After annealing, X-ray diffraction shows that we have synthesized the γ'-(Fe 1- x Cu x ) 4 N (0.05≤x≤0.15) compounds. The films were investigated by Moessbauer spectroscopy. The crystallographic structure and the respective positions of the Fe and Cu atoms in the compounds have been determined

  5. Raman scattering, magnetization and magnetotransport study of SrFeO3-δ, Sr3Fe2O7-δ and CaFeO3

    International Nuclear Information System (INIS)

    Damljanovic, Vladimir

    2008-01-01

    In this thesis we have determined the Raman spectra as well as the magnetization, resistance and magnetoresistance of the compounds SrFeO 3-δ , Sr 3 Fe 2 O 7-δ and CaFeO 3 as a function of temperature. We describe the preparation of nearly stoichiometric SrFeO 3-δ crystals with δ 3.00 in order to assign the phonon modes observed in infra-red experiments. We have measured the Raman spectra of the tetragonal phase in the temperature range 13 K to 300 K and of the orthorhombic phase in the temperature range 6 K to 475 K. We have measured the temperature dependence of the magnetization for the magnetic field along high-symmetry axes of the crystal structure. We have also performed neutron diffraction measurements. The resistivity and the magnetoresistance were measured in the range 10 K to 300 K. Finally we have measured the Raman spectra of the same sample in the temperature range 15 K to 440 K. In order to assign the observed modes, we have performed lattice dynamics calculations based on the published crystal structure of Sr 3 Fe 2 O 7 . (orig.)

  6. Magnetic Properties and Microstructure of FeOx/Fe/FePt and FeOx/FePt Films

    Directory of Open Access Journals (Sweden)

    Jai-Lin Tsai

    2013-01-01

    Full Text Available The Fe(6 nm/FePt film with perpendicular magnetization was deposited on the glass substrate. To study the oxygen diffusion effect on the coupling of Fe/FePt bilayer, the plasma oxidation with 0.5~7% oxygen flow ratio was performed during sputtered part of Fe layer and formed the FeOx(3 nm/Fe(3 nm/FePt trilayer. Two-step magnetic hysteresis loops were found in trilayer with oxygen flow ratio above 1%. The magnetization in FeOx and Fe/FePt layers was decoupled. The moments in FeOx layer were first reversed and followed by coupled Fe/FePt bilayer. The trilayer was annealed again at 500°C and 800°C for 3 minutes. When the FeOx(3 nm/Fe(3 nm/FePt trilayer was annealed at 500°C, the layers structure was changed to FeOx(6 nm/FePt bilayer due to oxygen diffusion. The hard-magnetic FeOx(6 nm/FePt film was coupled with single switching field. The FeOx/(disordered FePt layer structure was observed with further annealing at 800°C and presented soft-magnetic loop. In summary, the coupling between soft-magnetic Fe, FeOx layer, and hard-magnetic L10 FePt layer can be controlled by the oxygen diffusion behavior, and the oxidation of Fe layer was tuned by the annealing temperature. The ordered L10 FePt layer was deteriorated by oxygen and became disordered FePt when the annealed temperature was up to 800°C.

  7. Mechanically - induced disorder in CaFe2As2: a 57Fe Mössbauer study

    Science.gov (United States)

    Ma, Xiaoming; Ran, Sheng; Canfield, Paul C.; Bud'Ko, Sergey L.

    57 Fe Mössbauer spectroscopy was used to study an extremely pressure and strain sensitive compound, CaFe2As2, with different degrees of strain introduced by grinding and annealing. At the base temperature, in the antiferromagnetic/orthorhombic phase, compared to a sharp sextet Mössbauer spectrum of single crystal CaFe2As2, which is taken as an un-strained sample, an obviously broadened sextet and an extra doublet were observed for ground CaFe2As2 powders with different degrees of strain. The Mössbauer results suggest that the magnetic phase transition of CaFe2As2 can be inhomogeneously suppressed by the grinding induced strain to such an extent that the antiferromagnetic order in parts of the grains forming the powdered sample remain absent all the way down to 4.6 K. However, strain has almost no effect on the temperature dependent hyperfine magnetic field in the grains with magnetic order. The quadrupole shift in the magnetic phase approachs zero with increasing degrees of strain, indicating that the strain reduces the average lattice asymmetry at Fe atom position. Supported by US DOE under the Contract No. DE-AC02-07CH11358 and by the China Scholarship Council.

  8. Magnetism and large magnetocaloric effect in HoFe{sub 2-x}Al{sub x}

    Energy Technology Data Exchange (ETDEWEB)

    Mican, S., E-mail: sever.mican@ubbcluj.ro [Babes-Bolyai University Cluj-Napoca, RO-400084 Cluj-Napoca (Romania); Benea, D., E-mail: diana.benea@phys.ubbcluj.ro [Babes-Bolyai University Cluj-Napoca, RO-400084 Cluj-Napoca (Romania); Tetean, R., E-mail: romulus.tetean@phys.ubbcluj.ro [Babes-Bolyai University Cluj-Napoca, RO-400084 Cluj-Napoca (Romania)

    2013-02-05

    Highlights: Black-Right-Pointing-Pointer Structural, magnetic and magnetocaloric properties of HoFe{sub 2-x}Al{sub x} compounds are reported. Black-Right-Pointing-Pointer Electronic structure calculations show a good agreement between theory and experiment. Black-Right-Pointing-Pointer Magnetic transitions close to room temperature for the Fe-rich samples. Black-Right-Pointing-Pointer High values of the relative cooling power for all of the investigated samples. Black-Right-Pointing-Pointer No hysteresis losses in applied fields of up to 4 T. - Abstract: The structural, magnetic and magnetocaloric properties of several HoFe{sub 2-x}Al{sub x} compounds were investigated. The compounds in the Fe-rich region (0.36 Less-Than-Or-Slanted-Equal-To x Less-Than-Or-Slanted-Equal-To 0.4) crystallize in the cubic MgCu{sub 2} (C15) structure, while for the ones in the intermediate region (0.75 Less-Than-Or-Slanted-Equal-To x Less-Than-Or-Slanted-Equal-To 1.125) the hexagonal MgZn{sub 2} (C14) structure was observed. Electronic structure calculations were performed, showing a good agreement between theory and experiment. The Curie temperatures were found to decrease with Al content. For the Fe-rich compounds, these are close to room temperature, while for the compounds in the intermediate region, transition temperatures are well below 300 K. No magnetic hysteresis was found around the Curie temperature for applied magnetic fields of up to 4 T. All of the investigated compounds undergo a second-order magnetic phase transition at the Curie temperature. A maximum magnetic entropy change value of 7.6 J/kg K was obtained for the sample with x = 1.125, all of the samples displaying rather large RCP values. The possibility of incorporating these materials in magnetic refrigeration devices is discussed.

  9. A structural, magnetic and Moessbauer spectral study of the magnetocaloric Mn1.1Fe0.9P1-xGex compounds

    International Nuclear Information System (INIS)

    Sougrati, Moulay T; Hermann, Raphael P; Grandjean, Fernande; Long, Gary J; Brueck, E; Tegus, O; Trung, N T; Buschow, K H J

    2008-01-01

    The structural, magnetic and Moessbauer spectral properties of the magnetocaloric Mn 1.1 Fe 0.9 P 1-x Ge x compounds, with 0.19 1.1 Fe 0.9 P 0.74 Ge 0.26 . The temperature dependence of the magnetization reveals a ferromagnetic to paramagnetic transition with a Curie temperature between approximately 250 and 330 K and hysteresis width of 10 to 4 K, for 0.19 1.1 Fe 0.9 P 0.78 Ge 0.22 shows the largest isothermal entropy change of approximately 10 J/(kgKT) at 290 K. The Moessbauer spectra have been analysed with a binomial distribution of hyperfine fields correlated with a change in isomer shift and quadrupole shift, a distribution that results from the distribution of phosphorus and germanium among the near neighbours of the iron. The coexistence of paramagnetic and magnetically ordered phases in ranges of temperature of up to 50 K around the Curie temperature is observed in the Moessbauer spectra and is associated with the first-order character of the ferromagnetic to paramagnetic transition. The temperature dependence of the weighted average hyperfine field is well fitted within the magnetostrictive model of Bean and Rodbell. Good fits of the Moessbauer spectra could only be achieved by introducing a difference between the isomer shifts in the paramagnetic and ferromagnetic phases, a difference that is related to the magnetostriction and electronic structure change.

  10. HOMOTRINUCLEAR Fe3III μ – OXO SALICYLATE CLUSTER. SYNTHESIS, STRUCTURE AND PROPERTIES

    Directory of Open Access Journals (Sweden)

    Viorina Gorinchoy

    2013-12-01

    Full Text Available A reaction of iron and barium nitrate with ammonium salicylate in the mixture of solvents leads to the formation of the new homotrinuclear complex, [Fe3O(SalH7(H2O2]∙(DMAA2(MeOH(THF1,5(H2O2,6. Single-crystal X-ray study shows that the titled complex with the moiety {Fe3O} belongs to the well-known group of μ3-oxohomotrinuclear carboxylates. The IR and MS studies are in accordance with x-ray data. Thermal behaviour of the complex was studied.

  11. Effect of metal ion Fe(III on the performance of chlorophyll as photosensitizers on dye sensitized solar cell

    Directory of Open Access Journals (Sweden)

    Harsasi Setyawati

    Full Text Available The energy crisis is a major problem facing the world today and will need a renewable energy source that is environmentally friendly; one of these is the dye sensitized solar cell (DSSC. DSSC is photochemical electric cell that can convert solar energy into electrical energy. This research aims to study the characteristics of chlorophyll compounds with the addition of metal ions Fe(III and to determine the effect of Fe(III on the performance of chlorophyll as a photosensitizer in the DSSC. The formation of complex compounds of Fe(III-chlorophyll is shown by the phenomenon of metal ligand charge transfer (MLCT at a wavelength of 263.00 nm and absorption transition d-d at 745.00 nm. Fourier transform infrared characterization of the binding of Fe-O complex compounds appears at 486.06 cm−1. The complex compound of Fe(III-chlorophyll has a magnetic moment value of 9.62 Bohr Magneton (BM. The existence of ion Fe(III in chlorophyll can improve the performance of chlorophyll as a dye sensitizer with a maximum current of 4.00 mA/cm2, maximum voltage of 0.18 volts and efficiency values of 1.35%. Keywords: Fe(III-chlorophyll, Dye sensitized solar cell, Metal ligand charge transfer, Photosensitizer

  12. Large magnetoresistance in (AA')2FeReO6 double perovskites

    International Nuclear Information System (INIS)

    Teresa, J.M. de; Serrate, D.; Blasco, J.; Ibarra, M.R.; Morellon, L.

    2005-01-01

    We review the main structural, magnetic and magnetotransport properties of the intriguing (AA') 2 FeReO 6 magnetic double perovskites. As the average cation size decreases, the crystallographic structure at room temperature evolves from cubic [(AA') 2 =Ba 2 , Ba 1.5 Sr 0.5 , BaSr, Ba 0.5 Sr 1.5 ] to tetragonal [(AA') 2 =Sr 2 ] and monoclinic [(AA') 2 =Ca 0.5 Sr 1.5 , CaSr, Ca 1.5 Sr 0.5 , Ca 2 ]. The Curie temperature increases anomalously from ∼303K for Ba 2 to ∼522K for Ca 2 in sharp contrast with the observed behaviour in the isostructural compounds (AA') 2 FeMoO 6 . Other anomalous features in the (AA') 2 FeReO 6 series are: the large magnetic anisotropy, the large magnetoelastic coupling and the semiconducting behaviour of the monoclinic compounds. The monoclinic compounds undergo a structural/magnetic transition at T S below 125K. Three different magnetoresistance mechanisms have been identified: the intergrain negative magnetoresistance effect, which is present across the whole series of compounds, and in the case of the monoclinic compounds below T S a negative magnetoresistance effect associated to the melting of the low-temperature phase and a positive magnetoresistance effect only present in (AA') 2 =Ca 2 below T∼50K

  13. Anisotropic thermal expansion of La(n)(Ti,Fe)(n)O(3n + 2) (n = 5 and 6).

    Science.gov (United States)

    Wölfel, Alexander; Dorscht, Philipp; Lichtenberg, Frank; van Smaalen, Sander

    2013-04-01

    Crystal structures are reported for two perovskite-related compounds with nominal compositions La5(Ti(0.8)Fe(0.2))5O17 and La6(Ti(0.67)Fe(0.33))6O20 at seven different temperatures between 90 and 350 K. For both compounds no evidence of a structural phase transition in the investigated range of temperatures was found. The thermal expansions are found to be anisotropic, with the largest thermal expansion along a direction parallel to the slabs of these layered compounds. The origin of this anisotropy is proposed to be a temperature dependence of tilts of the octahedral (Ti,Fe)O6 groups. It is likely that the same mechanism will determine similar anisotropic thermal behaviour of other compounds A(n)B(n)O(3n + 2). The crystal structures have revealed partial chemical order of Ti/Fe over the B sites, with iron concentrated towards the centers of the slabs. Local charge compensation is proposed as the driving force for the chemical order, where the highest-valent cation moves to sites near the oxygen-rich borders of the slabs. A linear dependence on the site occupation fraction by Fe of the computed valences leads to extrapolated valence values close to the formal valence of Ti(4+) for sites fully occupied by Ti, and of Fe(3+) for sites fully occupied by Fe. These results demonstrate the power of the bond-valence method, and they show that refined oxygen positions are the weighted average of oxygen positions in TiO6 and FeO6 octahedral groups.

  14. Magnetic properties of LaFe13-xAlxNy compounds

    International Nuclear Information System (INIS)

    Liu, J.P.; Tang, N.; Boer, F.R. de; Chatel, P.F. de; Buschow, K.H.J.

    1995-01-01

    Interstitial nitrides of the type LaFe 13-x Al x N y have been synthesized and their magnetic properties have been investigated. It is found that the magnetic properties are drastically modified by the introduction of interstitial nitrogen. The physical origin of the changes is discussed. ((orig.))

  15. INIS: Authority list for journal titles

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-03-01

    This is the twenty-ninth revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). It lists the titles of 12 990 journals which have contained articles within the scope of INIS. The purpose of this report is to provide descriptive cataloguers with a standard entry for the full title of a journal. In addition to the full journal title, the ISSN (International Standard Serial Number), administered by the ISSN International Centre, Paris, France, and/or CODEN, assigned by Chemical Abstracts Service, USA, are given in this manual. In order to help the reader to find titles easily, the list is divided into two parts. In Part I, the full journal titles are grouped by country or international organization responsible for coverage and ordered alphabetically. In Part II, the full journal titles of all countries or international organizations are arranged alphabetically. The country name or the international organization name responsible for coverage of the journal title to INIS is entered in parentheses. Journal titles marked with an asterisk are regularly scanned by INIS. Titles that have been identified by INIS Centres as 'Key Journals' are marked with the hash sign.

  16. INIS: Authority list for journal titles

    International Nuclear Information System (INIS)

    2003-01-01

    This is the twenty-ninth revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). It lists the titles of 12 990 journals which have contained articles within the scope of INIS. The purpose of this report is to provide descriptive cataloguers with a standard entry for the full title of a journal. In addition to the full journal title, the ISSN (International Standard Serial Number), administered by the ISSN International Centre, Paris, France, and/or CODEN, assigned by Chemical Abstracts Service, USA, are given in this manual. In order to help the reader to find titles easily, the list is divided into two parts. In Part I, the full journal titles are grouped by country or international organization responsible for coverage and ordered alphabetically. In Part II, the full journal titles of all countries or international organizations are arranged alphabetically. The country name or the international organization name responsible for coverage of the journal title to INIS is entered in parentheses. Journal titles marked with an asterisk are regularly scanned by INIS. Titles that have been identified by INIS Centres as 'Key Journals' are marked with the hash sign

  17. Crystal structure, IR and Mössbauer spectroscopy and magnetic properties of KZnFe(PO{sub 4}){sub 2} related to the zeolite-ABW-like compounds

    Energy Technology Data Exchange (ETDEWEB)

    Badri, Abdessalem [UR Matériaux Inorganiques, Faculté des Sciences, Université de Monastir, Monastir 5019 (Tunisia); Hidouri, Mourad, E-mail: mourad_hidouri@yahoo.fr [UR Matériaux Inorganiques, Faculté des Sciences, Université de Monastir, Monastir 5019 (Tunisia); Wattiaux, Alain [Institut de Chimie de la Matière Condensée de Bordeaux, CNRS, Université de Bordeaux I, 87 Avenue du Dr. A. Schweitzer, Pessac-Cedex 33608 (France); López, María Luisa; Veiga, María Luisa [Departamento de Química Inorgánica I, Facultad de Ciencias Químicas, Universidad Complutense, Madrid 28040 (Spain); Amara, Mongi Ben [UR Matériaux Inorganiques, Faculté des Sciences, Université de Monastir, Monastir 5019 (Tunisia)

    2014-07-01

    Highlights: • The reported structure of KZnFe(PO{sub 4}){sub 2} is closely related to the zeolite ABW-type. • The structure is described in detail. • The IR and Mössbauer spectroscopy results are reported. • The magnetic properties are developed. - Abstract: The new iron phosphate KZnFe(PO{sub 4}){sub 2} has been synthesized by flux method and solid state reaction, and characterized by X-ray diffraction, IR, Mössbauer spectroscopy and magnetic susceptibility. This compound crystallizes in the monoclinic space group C2/c with the cell parameters: a = 13.514(4) Å, b = 13.273(6) Å, c = 8.742(3) Å and β = 100.07(2)°. It displays strong similarities with the phosphates KCoAl(PO{sub 4}){sub 2} and NaCoPO{sub 4} and features some analogies with the zeolite-ABW structural type. 3D framework is built up by a corner-sharing between MO{sub 4} (M = 0.5 Zn + 0.5 Fe) and PO{sub 4} tetrahedra. The K{sup +} ions are found within crossing tunnels perpendicular to the (1 0 0), (0 1 0) and (0 0 1) planes, delimited by this framework. A Mössbauer study confirmed the presence of Fe{sup 3+} ions in a tetrahedral environment. Magnetic measurements revealed an antiferromagnetic behavior with T{sub N} = 8.5 K.

  18. Mössbauer study of oxide films of Fe-, Sn-, Cr- doped zirconium alloys during corrosion in autoclave

    Energy Technology Data Exchange (ETDEWEB)

    Filippov, V. P., E-mail: vpfilippov@mephi.ru; Bateev, A. B.; Lauer, Yu. A. [National Research Nuclear University “MEPhI” (Moscow Engineering Physics Institute) (Russian Federation)

    2016-12-15

    Mössbauer investigations were used to compare iron atom states in oxide films of binary Zr-Fe, ternary Zr-Fe-Cu and quaternary Zr-Fe-Cr-Sn alloys. Oxide films are received in an autoclave at a temperature of 350–360 °C and at pressure of 16.8 MPa. The corrosion process decomposes the intermetallic precipitates in alloys and forms metallic iron with inclusions of chromium atoms α–Fe(Cr), α–Fe(Cu), α–Fe {sub 2}O{sub 3} and Fe {sub 3}O{sub 4} compounds. Some iron ions are formed in divalent and in trivalent paramagnetic states. The additional doping influences on corrosion kinetics and concentration of iron compounds and phases formed in oxide films. It was shown the correlation between concentration of iron in different chemical states and corrosion resistance of alloys.

  19. Permanent magnetic properties of NdFe12Nx sputtered films epitaxially grown on V buffer layer

    Science.gov (United States)

    Sato, T.; Ohsuna, T.; Yano, M.; Kato, A.; Kaneko, Y.

    2017-08-01

    To clarify the magnetic properties of the NdFe12Nx compound, which shows promise as a high-performance permanent magnet material, NdFe12Nx epitaxial films fabricated by using a V underlayer on MgO (100) single-crystalline substrates were investigated. Nd-Fe films deposited on a V underlayer consist of NdFe12 grains, which have a c-axis orientation perpendicular to the film plane, as well as α-Fe and Nd2Fe17 phases. In the Nd-Fe-N film obtained by subsequent nitridation of the Nd-Fe film, NdFe12Nx grains grew as the dominant phase, and the volume fractions of α-Fe phases dropped below 5%. A Nd-Fe-N film with a thickness of 50 nm exhibits a saturation magnetization (Ms) of 1.7 T, an anisotropy field (HA) of ˜60 kOe, a magnetocrystalline anisotropy energy (K1) of ˜4.1 MJ/m3, and a coercivity (Hc) of 1.7 kOe. The Hc of a Nd-Fe-N film with a thickness of 25 nm is 4.3 kOe. These results indicate that NdFe12Nx compounds have a superior Ms compared to Nd-Fe-B magnets, while the enhancement in Hc is indispensable.

  20. Synthesis, crystal structure, and magnetic properties of quaternary iron selenides: Ba{sub 2}FePnSe{sub 5} (Pn=Sb, Bi)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian; Greenfield, Joshua T.; Kovnir, Kirill

    2016-10-15

    Two new barium iron pnictide–selenides, Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5}, were synthesized by a high-temperature solid-state route and their crystal structures were determined using single crystal X-ray diffraction. Both compounds are isomorphic to the high pressure phase Ba{sub 3}FeS{sub 5} and crystallize in the orthorhombic space group Pnma (No. 62) with cell parameters of a=12.603(2)/12.619(2) Å, b=9.106(1)/9.183(1) Å, c=9.145(1)/9.123(1) Å and Z=4 for Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5}, respectively. According to differential scanning calorimetry, Ba{sub 2}FePnSe{sub 5} compounds exhibit high thermal stability and melt congruently at 1055(5) K (Pn=Sb) and 1105(5) K (Pn=Bi). Magnetic characterizations reveal strong antiferromagnetic nearest-neighbor interactions in both compounds resulting in an antiferromagnetic ordering at 58(1) K for Ba{sub 2}FeSbSe{sub 5} and 79(2) K for Ba{sub 2}FeBiSe{sub 5}. The magnetic interactions between Fe{sup 3+} centers, which are at least 6 Å apart from each other, are mediated by superexchange interactions. - Graphical abstract: In Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5} the magnetic interactions between Fe{sup 3+} centers, which are at least 6 Å apart from each other, are mediated by superexchange interactions. - Highlights: • New compounds Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5} have been synthesized. • The crystal structure was determined by single crystal X-ray diffraction. • Both compounds melt congruently at temperatures above 1000 K. • Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5} exhibit AFM ordering at 58 K (Sb) and 70 K (Bi). • Magnetic exchange between Fe{sup 3+} is mediated by either Se–Sb(Bi)–Se or Se–Ba–Se bridges.

  1. Browse Title Index

    African Journals Online (AJOL)

    Items 201 - 250 of 488 ... African Journal of Paediatric Surgery. ... Ileocecal valve atresia: Introduction of a new surgical approach ... Vol 4, No 1 (2007), Isolated Bilateral Macrostomia: Case Series and ... Vol 9, No 2 (2012), Laparoscopic inguinal hernia repair in ... List All Titles · Free To Read Titles This Journal is Open Access.

  2. Crystal structures and magnetic properties of iron (III)-based phosphates: Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Essehli, Rachid, E-mail: rachid_essehli@yahoo.fr [Laboratory of Mineral Solid and Analytical Chemistry ' LCSMA' , Department of Chemistry, Faculty of Sciences, University Mohamed I, Po. Box 717, 60000 Oujda (Morocco); Bali, Brahim El [Laboratory of Mineral Solid and Analytical Chemistry ' LCSMA' , Department of Chemistry, Faculty of Sciences, University Mohamed I, Po. Box 717, 60000 Oujda (Morocco); Benmokhtar, Said [LCMS, Laboratoire de Chimie des Materiaux Solides, Departement de chimie, Faculte des Sciences Ben M' SIK, Casablanca (Morocco); Bouziane, Khalid [Physics Department, College of Science, Sultan Qaboos University, PO Box 36, Postal Code 123 Al Khod, Sultanate of Oman (Oman); Manoun, Bouchaib [Laboratoire de Physico-Chimie des Materiaux, Departement de Chimie, FST Errachidia, University Moulay Ismail, B.P. 509 Boutalamine, Errachidia (Morocco); Abdalslam, Mouner Ahmed [Materials Science, Technical University Darmstadt, Darmstadt (Germany); Ehrenberg, Helmut [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)

    2011-01-28

    Graphical abstract: A perspective view of the Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3} structure along the [0 0 1] direction. Both compounds seem to exibit antiferromagnetic interactions between magnetic entities at low temperature. Display Omitted Research highlights: > Nasicon and Alluaudite compounds, Iron(III)-based phosphates, Crystal structures of Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}. > Magnetism behaviours of Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}. > Antiferromagnetism interactions. > Mossbauer spectroscopy. - Abstract: Crystal structures from two new phosphates Na{sub 4}NiFe(PO{sub 4}){sub 3} (I) and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3} (II) have been determined by single crystal X-ray diffraction analysis. Compound (I) crystallizes in a rhombohedral system (S. G: R-3c, Z = 6, a = 8.7350(9) A, c = 21.643(4) A, R{sub 1} = 0.041, wR{sub 2}=0.120). Compound (II) crystallizes in a monoclinic system (S. G: C2/c, Z = 4, a = 11.729(7) A, b = 12.433(5) A, c = 6.431(2) A, {beta} = 113.66(4){sup o}, R{sub 1} = 0.043, wR{sub 2}=0.111). The three-dimensional structure of (I) is closely related to the Nasicon structural type, consisting of corner sharing [(Ni/Fe)O{sub 6}] octahedra and [PO{sub 4}] tetrahedra forming [NiFe(PO{sub 4}){sub 3}]{sup 4+} units which align in chains along the c-axis. The Na{sup +} cations fill up trigonal antiprismatic sites within these chains. The crystal structure of (II) belongs to the alluaudite type. Its open framework results from [Ni{sub 2}O{sub 10}] units of edge-sharing [NiO{sub 6}] octahedra, which alternate with [FeO{sub 6}] octahedra that form infinite chains. Coordination of these chains yields two distinct tunnels in which site Na{sup +}. The magnetization data of compound (I) reveal antiferromagnetic (AFM) interactions by the onset of deviations from a Curie-Weiss behaviour at low temperature as confirmed by Moessbauer measurements performed at 4.2 K. The

  3. Effect of some factors on foliar absorption and mobility of Fe59 in plant

    International Nuclear Information System (INIS)

    Mohamed, F.A.

    1990-01-01

    Three experiments were conducted under greenhouse conditions using Fe 59 and seedlings of guava and orange to study the effect of PH value (3-8), Fe SO 4 concentrations in combination with three values of PH on foliar absorption and mobility of Fe. In addition, a comparative study to evaluate some compounds of iron for foliar spray was achieved. Foliar absorption of Fe 59 by guava leaves and its mobility were considerably influenced by PH value of spray solution. Maximum absorption and translocation were observed at PH 6. However, most of the absorbed iron 'about 90%' was retained in the treated leaves and the portion 'about 10%' acropetally and basipetally translocated. Upward transport of iron was more pronounced than downward one. Total iron in plant derived from applied FeSO 4 was greatly increased, whereas utilization percent of it was reduced by increasing the rate of Fe in spray solution. Generally, FeSO 4 had a good efficiency which ranged from about 25-43%. Specific absorption of iron by orange leaves was higher than that of guava leaves. From plant nutritional point of view, efficiency of FeSo 4 , Fe-metalosate and multi mineral-metalosate as different sources of Fe through foliar application remarkably varied and FeSO 4 was highly efficient one in comparison with metalosate compounds

  4. Effects of iron on intermetallic compound formation in scandium modified Al–Si–Mg Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Patakham, Ussadawut [National Metal and Materials Technology Center, National Science and Technology Development Agency, 114 Thailand Science Park, Klong Nueng, Klong Luang, Pathumthani 12120 (Thailand); Limmaneevichitr, Chaowalit, E-mail: chaowalit.lim@mail.kmutt.ac.th [Production Engineering Department, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand)

    2014-12-15

    Highlights: • Iron reduces the modification effects of scandium in Al–Si–Mg alloys. • Morphologies of Sc-rich intermetallic phases vary with Fe and Sc contents and the cooling rates. • Sc neutralizes effects of Fe by changing Fe-rich intermetallic phases from platelets to more cubic. - Abstract: In general, iron has a strong tendency to dissolve in molten aluminum. Iron has very low solid solubility in aluminum–silicon casting alloys, so it will form intermetallic compounds that cause detrimental effects on mechanical properties. In this work, the effects of iron on intermetallic compound formations in scandium modified Al–Si–Mg alloys were studied. There were two levels of iron addition (0.2 and 0.4 wt.%) and two levels of scandium addition (0.2 and 0.4 wt.%). We found that the effects of scandium modification decreased with increasing iron addition. The morphologies of the complex intermetallic compounds were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) techniques. It was found that scandium changes the morphology of Fe-rich intermetallic compounds from β-phase (plate-like) to α-phase, which reduces the harmful effects of β-phase.

  5. The direct hydroxylation of benzene to phenol catalyzed by Fe-ZSM-5 zeolite : a DFT and hybrid MP2:DFT calculation

    NARCIS (Netherlands)

    Yang, Z.; Yang, G.; Liu, X.; Han, Xiuwen

    2013-01-01

    The title reactions over Fe-III and Fe-II-ZSM-5 zeolites are divided into seven and six steps, wherein the M06L:B3LYP energy barriers of N2O decomposition to form active site, benzene activation to form C-O bond and proton transfer to form phenol are equal to 37.0, 13.7, 17.2 and 33.7, 3.0, 19.1

  6. Identification of new phases in the Zr-Nb-Fe system

    International Nuclear Information System (INIS)

    Granovsky, Marta S.; Arias, Delia E.; Lena, Esteban M.

    1999-01-01

    Intermediate phases in the Zr - rich region of the Zr - Nb - Fe system have been investigated by X-ray diffraction, optical and electron microscopy and electron microanalysis. The chemical composition ranges of the alloys here studied were (52 - 97) at. % Zr, (14 - 0.9) at. % Nb and (38 - 0.6) at. % Fe. The phases found in this region were the solid solutions α(Zr) and β(Zr), the intermetallic Zr 3 Fe with less than 0.2 at. % Nb in solution, and two new ternary phases: (Zr + Nb) 2 Fe, identified as a cubic Ti 2 Ni - type structure and another compound with composition close to Zr - 12 at. % Nb - 50 at. % Fe. (author)

  7. Magnetic properties of PrMn2-xFexGe2-57Fe Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Wang, J L; Campbell, S J; Cadogan, J M; Tegus, O; Studer, A J; Hofmann, M

    2006-01-01

    We have investigated the magnetic behaviour of PrMn 2-x Fe x Ge 2 compounds with x = 0.4, 0.6 and 0.8 over the temperature range 4.2-350 K using ac magnetic susceptibility, dc magnetization and 57 Fe Moessbauer effect spectroscopy, as well as neutron diffraction for the PrMn 1.2 Fe 0.8 Ge 2 compound. Replacement of Mn with Fe leads to contraction of the unit cell and a shortening of the Mn-Mn spacing, resulting in modification of the magnetic structure. PrMn 1.6 Fe 0.4 Ge 2 is an intralayer antiferromagnet at room temperature and ferromagnetic below T C inter ∼230 K with additional ferromagnetic ordering of the Pr sublattice detected below T C Pr ∼30 K. Re-entrant ferromagnetism has been observed in PrMn 1.4 Fe 0.6 Ge 2 with four magnetic transitions (T N intra ∼333 K, T C inter ∼168 K, T N inter ∼152 K and T C Pr ∼40 K). Moreover, it was found that T C inter and T C Pr increase with applied field while T N inter decreases. PrMn 1.2 Fe 0.8 Ge 2 is antiferromagnetic with T N intra ∼242 K and T N inter ∼154 K. The magnetic transition temperatures for all compounds are also marked by changes in the 57 Fe magnetic hyperfine field and the electric quadrupole interaction parameters. The 57 Fe transferred hyperfine field at 4.5 K in PrMn 1.6 Fe 0.4 Ge 2 and PrMn 1.4 Fe 0.6 Ge 2 is reduced (below the ordering temperature of the Pr sublattice) compared with that at 80 K (above T C Pr ), indicating that the transferred hyperfine field from Pr acts in the opposite direction to that from the Mn atoms. The neutron data for PrMn 1.2 Fe 0.8 Ge 2 demonstrate that an anisotropic thermal expansion occurs within the interplanar antiferromagnetic range

  8. Removal of cyanide compounds from coking wastewater by ferrous sulfate: Improvement of biodegradability.

    Science.gov (United States)

    Yu, Xubiao; Xu, Ronghua; Wei, Chaohai; Wu, Haizhen

    2016-01-25

    The effect of ferrous sulfate (FeSO4) treatment on the removal of cyanide compounds and the improvement of biodegradability of coking wastewater were investigated by varying Fe:TCN molar ratios. Results suggested that the reaction between FeSO4 and coking wastewater was a two-step process. At the first step, i.e., 0≤Fe:TCN≤1.0, the reaction mechanisms were dominated by the precipitation of FeS, the complexation of CN(-), and the coagulation of organic compounds. The COD of coking wastewater decreased from 3748.1 mg/L to 3450.2 mg/L, but BOD5:COD (B/C) was improved from 0.30 to 0.51. At the second step, i.e., 1.0cyanide compounds by ferrous ions was the dominating mechanism. The COD showed a continuous increase to 3542.2 mg/L (Fe:TCN=3.2) due to the accumulated ferrous ions in coking wastewater. Moreover, B/C decreased progressively to 0.35, which was attributed to the negative effects of excess ferrous ions on biodegradability. To improve coking wastewater's biodegradability, a minimum ferrous dosage is required to complete the first step reaction. However, the optimum ferrous dosage should be determined to control a safe residual TCN in coking wastewater for the further biological treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Thermodynamic properties of Heusler Fe2VSi

    Science.gov (United States)

    Ito, Masakazu; Kai, Keita; Furuta, Tatsuya; Manaka, Hirotaka; Terada, Norio; Hiroi, Masahiko; Kondo, Akihiro; Kindo, Koichi

    2018-05-01

    We investigated temperature, T, dependence of magnetization, M(T), electrical resistivity, ρ(T), and specific heat, Cp(T), for the Heusler compound Fe2VSi. M(T) shows anomalies at TN1 ˜ 115 K and at TN2 ˜ 35 K. The anomaly at TN1 is caused by the magnetic transition with a crystal structural change. On the other hand, ρ(T) and Cp(T) show only anomaly at TN1, and no trace of anomaly at TN2 is observed. Because of the irreversibility of M(T), which is the characteristic of spin-glass freezing, appears below TN2, a spin-glass freezing may occur at TN2. From the analogy of the Heusler compound (Fe1-xVx ) 3Si with the cubic D03 crystal structure, (0 ≤ x ≤ 0.2), we suggested that the atomic disorder of V site by the Fe atoms gives rise to the magnetic frustration. This could be cause for the spin-glass freezing. By the Clausius-Clapeyron relation, pressure, P, derivative of TN1, (d/TN 1 d P ), is estimated to be ˜-10 K/Gpa.

  10. [Corrected Title: Solid-Phase Extraction of Polar Compounds from Water] Automated Electrostatics Environmental Chamber

    Science.gov (United States)

    Sauer, Richard; Rutz, Jeffrey; Schultz, John

    2005-01-01

    A solid-phase extraction (SPE) process has been developed for removing alcohols, carboxylic acids, aldehydes, ketones, amines, and other polar organic compounds from water. This process can be either a subprocess of a water-reclamation process or a means of extracting organic compounds from water samples for gas-chromatographic analysis. This SPE process is an attractive alternative to an Environmental Protection Administration liquid-liquid extraction process that generates some pollution and does not work in a microgravitational environment. In this SPE process, one forces a water sample through a resin bed by use of positive pressure on the upstream side and/or suction on the downstream side, thereby causing organic compounds from the water to be adsorbed onto the resin. If gas-chromatographic analysis is to be done, the resin is dried by use of a suitable gas, then the adsorbed compounds are extracted from the resin by use of a solvent. Unlike the liquid-liquid process, the SPE process works in both microgravity and Earth gravity. In comparison with the liquid-liquid process, the SPE process is more efficient, extracts a wider range of organic compounds, generates less pollution, and costs less.

  11. Content and Phrasing in Titles of Original Research and Review Articles in 2015: Range of Practice in Four Clinical Journals

    Directory of Open Access Journals (Sweden)

    Mary Ellen Kerans

    2016-04-01

    Full Text Available Reporting guidelines for clinical research designs emerged in the mid-1990s and have influenced various aspects of research articles, including titles, which have also been subject to changing uses with the growth of electronic database searching and efforts to reduce bias in literature searches. We aimed (1 to learn more about titles in clinical medicine today and (2 to develop an efficient, reliable way to study titles over time and on the fly—for quick application by authors, manuscript editors, translators and instructors. We compared content and form in titles from two general medical journals—the New England Journal of Medicine (NEJM and the British Medical Journal—and two anesthesiology journals (the European Journal of Anaesthesiology and Anesthesiology; we also analyzed the inter-rater reliability of our coding. Significant content differences were found in the frequencies of mentions of methods, results (between general and subspecialty titles, and geographic setting; phrasing differences were found in the prevalence of full-sentence and compound titles (and their punctuation. NEJM titles were significantly shorter, and this journal differed consistently on several features. We conclude that authors must learn to efficiently survey titles for form and content patterns when preparing manuscripts to submit to unfamiliar journals or on resubmitting to a new journal after rejection.

  12. Na7 [Fe2S6 ] , Na2 [FeS2 ] and Na2 [FeSe2 ] : New 'reduced' sodium chalcogenido ferrates

    Science.gov (United States)

    Stüble, Pirmin; Peschke, Simon; Johrendt, Dirk; Röhr, Caroline

    2018-02-01

    Three new 'reduced' FeII containing sodium chalcogenido ferrates were obtained applying a reductive synthetic route. The mixed-valent sulfido ferrate Na7 [Fe2S6 ] , which forms bar-shaped crystals with metallic greenish luster, was synthesized in pure phase from natural pyrite and elemental sodium at a maximum temperature of 800 °C. Its centrosymmetric triclinic structure (SG P 1 bar , a = 764.15(2), b = 1153.70(2), c = 1272.58(3) pm, α = 62.3325 (7) , β = 72.8345 (8) , γ = 84.6394 (8) ° , Z = 3, R1 = 0.0185) exhibits two crystallographically different [Fe2S6 ] 7 - dimers of edge-sharing [FeS4 ] tetrahedra, with somewhat larger Fe-S distances than in the fully oxidized FeIII dimers of e.g. Na6 [Fe2III S6 ] . In contrast to the localized AFM ordered pure di-ferrates(III), the Curie-Weiss behavior of the magnetic susceptibility proves the rarely observed valence-delocalized S = 9/2 state of the mixed-valent FeIII /FeII dimer. The nearly spin-only value of the magnetic moment combined with the chemical bonding not generally differing from that in pure ferrates(II) and (III), provides a striking argument, that the reduction of the local Fe spin moments observed in all condensed sulfido ferrate moieties is connected with the AFM spin ordering. The two isotypic ferrates(II) Na2 [FeS2 ] and Na2 [FeSe2 ] with chain-like structural units (SG Ibam, a = 643.54(8)/ 660.81(1), b = 1140.2(2)/1190.30(2) c = 562.90(6)/585.59(1) pm, Z = 4, R1 = 0.0372/0.0466) crystallize in the K2 [ZnO2 ] -type structure. Although representing merely further members of the common series of chalcogenido metallates(II) Na2 [MIIQ2 ] , these two new phases, together with Na6 [FeS4 ] and Li2 [FeS2 ] , are the only examples of pure FeII alkali chalcogenido ferrates. The new compounds allow for a general comparison of di- and chain ferrates(II) and (III) and mixed-valent analogs concerning the electronic and magnetic properties (including Heisenberg super-exchange and double-exchange interactions

  13. 2-(Substituted phenyl-3,4-dihydroisoquinolin-2-iums as Novel Antifungal Lead Compounds: Biological Evaluation and Structure-Activity Relationships

    Directory of Open Access Journals (Sweden)

    Xin-Juan Yang

    2013-08-01

    Full Text Available The title compounds are a class of structurally simple analogues of quaternary benzo[c]phenanthridine alkaloids (QBAs. In order to develop novel QBA-like antifungal drugs, in this study, 24 of the title compounds with various substituents on the N-phenyl ring were evaluated for bioactivity against seven phytopathogenic fungi using the mycelial growth rate method and their SAR discussed. Almost all the compounds showed definite activities in vitro against each of the test fungi at 50 μg/mL and a broad antifungal spectrum. In most cases, the mono-halogenated compounds 2–12 exhibited excellent activities superior to the QBAs sanguinarine and chelerythrine. Compound 8 possessed the strongest activities on each of the fungi with EC50 values of 8.88–19.88 µg/mL and a significant concentration-dependent relationship. The SAR is as follows: the N-phenyl group is a high sensitive structural moiety for the activity and the characteristics and position of substituents intensively influence the activity. Generally, electron-withdrawing substituents remarkably enhance the activity while electron-donating substituents cause a decrease of the activity. In most cases, ortha- and para-halogenated isomers were more active than the corresponding m-halogenated isomers. Thus, the title compounds emerged as promising lead compounds for the development of novel biomimetic antifungal agrochemicals. Compounds 8 and 2 should have great potential as new broad spectrum antifungal agents for plant protection.

  14. Control of interfacial intermetallic compounds in Fe–Al joining by Zn addition

    Energy Technology Data Exchange (ETDEWEB)

    Yang, J. [Key Laboratory of Robot and Welding Automation of Jiangxi Province, School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Center for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Li, Y.L., E-mail: liyulong1112ster@gmail.com [Key Laboratory of Robot and Welding Automation of Jiangxi Province, School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Zhang, H. [Key Laboratory of Robot and Welding Automation of Jiangxi Province, School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Guo, W. [Center for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); School of Mechanical Engineering and Automation, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Zhou, Y. [Center for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada)

    2015-10-01

    By Zn addition to the fusion zone, the interfacial intermetallic compounds (IMCs) of laser Al/steel joint changed from layered Fe{sub 2}Al{sub 5} and needle-like FeAl{sub 3} to layered Fe{sub 2}Al{sub 5−x}Zn{sub x} and dispersed FeZn{sub 10} with minor Al-rich amorphous phase. This resulted in an improvement in the joint strength and the change of failure mode.

  15. Moessbauer Investigation of Spin Arrangements in Er2-xCexFe14B

    International Nuclear Information System (INIS)

    Bogacz, B.F.; Pedziwiatr, A.T.

    2008-01-01

    It was theoretically postulated earlier that in compounds Er 2-x Ce x Fe 14 B it may be possible to observe not only axial and planar spin arrangements but also a conical one. In order to experimentally verify this hypothesis, 57 Fe Moessbauer spectroscopy analysis was used to study the polycrystalline compounds Er 2-x Ce x Fe 14 B in the postulated composition region (x = 1.0, 1.1, 1.2, 1.3) in the wide range of temperatures. The obtained experimental data do not clearly support the suggestion of conical arrangement occurrence in the postulated compositions. They indicate that such phenomenon may be shifted towards higher Ce content. (authors)

  16. Compounds which mediate Gallium-67 transfer from lactoferrin to ferritin

    International Nuclear Information System (INIS)

    Weiner, R.E.; Schreiber, G.J.; Hoffer, P.B.; Bushberg, J.T.

    1985-01-01

    The influence of various low molecular weight compounds on the transfer of 67 Ga from human lactoferrin (LF) to horse spleen ferritin (HoFE) has been examined in vitro. When LF/sup */ 67 Ga complex was placed in competition with HoFE using a dialysis system the initial transfer rate (TR) of 67 Ga to HoFE was slow and continuous. In the presence of 1 mM pyrophosphate (PP/sub i/) ascorbate and adenosine triphosphate (ATP), the TR was dramatically enhanced. This effect was concentration sensitive since reduction of the ATP to 0.1 mM eliminated the enhancement. Although PP/sub i/ and ascorbate ions yielded larger TR's, ATP was more effective in the promotion of 67 Ga transfer to HoFE. When the LF/HoFE concentration ratio was decreased, in the presence of ATP, the transfer of 67 Ga was significantly increased. These results suggest that ferritin present intracellularly could remove and retain 67 Ga entering the cell in the form of a LF/sub */ 67 Ga complex. Moreover, increased synthesis of ferritin and cytosolic phosphate compounds would appear to enhance this process

  17. Green rusts synthesis by coprecipitation of Fe II-Fe III ions and mass-balance diagram

    Science.gov (United States)

    Ruby, Christian; Aïssa, Rabha; Géhin, Antoine; Cortot, Jérôme; Abdelmoula, Mustapha; Génin, Jean-Marie

    2006-06-01

    A basic solution is progressively added to various mixed Fe II-Fe III solutions. The nature and the relative quantities of the compounds that form can be visualised in a mass-balance diagram. The formation of hydroxysulphate green rust {GR( SO42-)} is preceded by the precipitation of a sulphated ferric basic salt that transforms in a badly ordered ferric oxyhydroxide. Then octahedrally coordinated Fe II species and SO42- anions are adsorbed on the FeOOH surface and GR( SO42-) is formed at the solid/solution interface. By using the same method of preparation, other types of green rust were synthesised, e.g. hydroxycarbonate green rust {GR( CO32-)}. Like other layered double hydroxides, green rusts obey the general chemical formula [ṡ[ṡmHO]x+ with x⩽1/3. Al-substituted hydroxysulphate green rust consists of small hexagonal crystals with a lateral size ˜50 nm, which is significantly smaller than the size of the GR( SO42-) crystals (˜500 nm). To cite this article: C. Ruby et al., C. R. Geoscience 338 (2006).

  18. Ion-beam mixing and tribology of Fe/B multilayers

    International Nuclear Information System (INIS)

    Hu, R.; Rehn, L.E.; Baldo, P.M.; Fenske, G.R.

    1990-01-01

    This paper reports the interdiffusion of Fe and B trilayer specimens during 1-MeV Kr + bombardment studied using Rutherford backscattering and electron microscopy. The square of the interdiffusion distance during mixing at 300 degrees C was found to depend linearly on the irradiation dose. Arrhenius behavior with an apparent activation enthalpy of 0.7 eV was observed for the mixing between 200 and 500 degrees C. Electron microscopy of ion-beam mixed multilayer specimens revealed that two crystalline compounds, Fe 2 B and Fe 3 B, formed during bombardment at 450 degrees C, while two different amorphous Fe/B phases formed at 300 degrees C. Substantially improved adhesion and reduced friction were observed for Fe/B multilayers ion-beam mixed onto M50 steel substrates at 450 degrees C

  19. Low-temperature rapid synthesis and superconductivity of Fe-based oxypnictide superconductors.

    Science.gov (United States)

    Fang, Ai-Hua; Huang, Fu-Qiang; Xie, Xiao-Ming; Jiang, Mian-Heng

    2010-03-17

    Fe-based oxypnictide superconductors were successfully synthesized at lower reaction temperatures and with shorter reaction times made possible by starting with less stable compounds, which provide a larger driving force for reactions. Using ball-milled powders of intermediate compounds, phase-pure superconductors with T(c) above 50 K were synthesized at 1173 K in 20 min. This method is particularly advantageous for retaining F, a volatile dopant that enhances superconductivity. Bulk superconductivity and high upper critical fields up to 392 T in Sm(0.85)Nd(0.15)FeAsO(0.85)F(0.15) were demonstrated.

  20. Mechanical alloying of the FeNi-Ag system

    International Nuclear Information System (INIS)

    Gonzalez, G.; Ibarra, D.; Ochoa, J.; Villalba, R.; Sagarzazu, A.

    2007-01-01

    The Fe-Ni-Ag system is of particular interest for its potential applications as soft magnetic granular material with small magnetic grains embedded in a non-magnetic metal matrix. Under equilibrium conditions: Fe-Ag and Ni-Ag are immiscible and Fe-Ni shows complete solubility. These materials are particularly important for magnetoresistivity properties. The properties of these alloys are closely related to their microstructure; therefore, a detailed study of the transformations occurring during milling was undertaken using pre-alloyed Fe x Ni 100-x (x = 30, 50 and 70) further milled with different Ag content to give the following alloys compositions (Fe x -Ni 100-x ) 100-y Ag y (y = 5, 20, 60). Consolidation of the mechanically alloyed powders by sintering at 950 o C was performed. Morphological and structural characterization of the sintered powders was carried out by scanning and transmission electron microscopy and X-ray diffraction. Fe 30 Ni 70 and Fe 50 Ni 50 formed ordered FeNi 3 compound. Fe 70 Ni 30 showed the formation of a mixture of γ-(Fe,Ni) and α-Fe(Ni) solid solutions. The mixture of these systems with Ag showed the metal solid solutions surrounded by Ag islands of Fe x Ni y -Ag, There was also evidence of Ag diffusing into the γ-(Fe,Ni). High Ag content (60%) shows formation of islands of FeNi surrounded by Ag. Sintering is always improved with the Ag content

  1. Determination of heats of formation of compounds melting incongruently

    Energy Technology Data Exchange (ETDEWEB)

    Kesler, Y.A.; Cheshnitskii, S.M.; Fotiev, A.A.; Tret' yakov, Y.D.

    1985-09-01

    Of significant interest is the development of new procedures for experimental determination of heats of formation of compounds, making it possible to expand the range of substances for which the standard, well-developed methods are unacceptable. The use of hightemperature Calvet microcalorimeters offers great possibilities for this. They recently have been used to determine the most important thermodynamic characteristics of many inorganic substances. In this paper the authors consider the use of drop calorimetry, i.e., the dropping of a sample thermostated at 298/sup 0/K into a calorimeter cell kept at a preassigned temperature for the study of peritecticdecomposition reactions of compounds, to determine their heats of formation. The authors used the compounds Fe/sub 2/V/sub 4/O/sub 13/ and FeVO/sub 4/, as well as high-purity V/sub 2/O/sub 5/.

  2. Magneto-structural correlations in a family of Fe(II)Re(IV)(CN)2 single-chain magnets: density functional theory and ab initio calculations.

    Science.gov (United States)

    Zhang, Yi-Quan; Luo, Cheng-Lin; Wu, Xin-Bao; Wang, Bing-Wu; Gao, Song

    2014-04-07

    Until now, the expressions of the anisotropic energy barriers Δξ and ΔA, using the uniaxial magnetic anisotropy D, the intrachain coupling strength J, and the high-spin ground state S for single-chain magnets (SCMs) in the intermediate region between the Ising and the Heisenberg limits, were unknown. To explore this relationship, we used density functional theory and ab initio methods to obtain expressions of Δξ and ΔA in terms of D, J, and S of six R4Fe(II)-Re(IV)Cl4(CN)2 (R = diethylformamide (1), dibutylformamide (2), dimethylformamide (3), dimethylbutyramide (4), dimethylpropionamide (5), and diethylacetamide (6)) SCMs in the intermediate region. The ΔA value for compounds 1-3 was very similar to the magnetic anisotropic energy of a single Fe(II), while the value of Δξ was predicted using the exchange interaction of Fe(II) with the neighboring Re(IV), which could be expressed as 2JSReSFe. Similar to compounds 1-3, the anisotropy energy barrier ΔA of compounds 4 and 5 was also equal to (Di - Ei)SFe(2), but the correlation energy Δξ was closely equal to 2JSReSFe(cos 98.4 - cos 180) due to the reversal of the spins on the opposite Fe(II). For compound 6, one unit cell of Re(IV)Fe(II) was regarded as a domain wall since it had two different Re(IV)-Fe(II) couplings. Thus, the Δξ of compound 6 was expressed as 4J″SRe1Fe1SRe2Fe2, where J″ was the coupling constant of the neighboring unit cells of Re1Fe1 and Re2Fe2, and ΔA was equal to the anisotropic energy barrier of one domain wall given by DRe1Fe1(S(2)Re1Fe1 - 1/4).

  3. Spectrophotometric speciation of Fe(II) and Fe(III) using hydrazone-micelle systems and flow injections

    International Nuclear Information System (INIS)

    Khojali, Inas Osman

    1999-04-01

    Two hydrazones were synthesised, namely salicylhyrazone (SH) and trihydroxyacetophenone (THAPH) were synthesised with the objective of developing a method for determining of Fe(II) and Fe(III) in the presence of each other and hence the total iron.those hydrazones were selected so as to combine the ability of phenolic compounds to complex Fe(III) ions and the complexing characteristics of hydrazones. The complexes of Fe(II) S H and Fe(III) S H as well those of Fe(II)-THAPH and Fe(III)-THAPH had shown maximum absorbance at λ=412 nm which was not not modified by presence of micelles i.e. sodium n-dodecyl sulphate (SDS) and n-hexa dodecyl pyridinium bromide. The maximum absorbance for all complexes takes place around a neutral pH. Generally, in addition, of n-hexa dodecylpyridinium bromide to fe(II)-SH and Fe(III)-SH absorbance of the complexes increases with increasing the concentration of the micelle. The effects of the addition of sodium n-dodecyle sulphate (SDS) to Fe(III)-SH is also studied. Generally, increasing the concentration of the micelle decrease the absorbance of the complexes. To study the effect of the presence of Fe(II) and Fe(III) on the determination of each other,mixtures of Fe(II)-SH and Fe(III)-SH are studied. However, the use of ascorbic acid as a reducing reagent for Fe(III) did not produce the needed results but non reducible results, which may be due to the masking effect of ascorbic acid and thus making the metal not available to the ligand. However, conversion of Fe(II) to Fe(III) prior to the determination was avoided as this requires the use of oxidant, which will oxidise the ligand as well. To establish the condition for the maximum absorbance of THAPH complexes, the effect of the base was investigated by using sodium and ammonium hydroxide. Generally, increasing the concentration of the base decreases the abosrbance. as expected, ammonium hydroxide produced positive results than sodium hydroxide. After establishing the optimum Fi

  4. Corrosion resistance of rigid bonded magnet MQP-0 (NdFeB compound) pre and post surface coating

    International Nuclear Information System (INIS)

    Purwanto, Setyo; Ihsan, M.; Mujamilah; Mashadi

    2002-01-01

    Rigid Bonded Magnet (RBM) MQP-0 (NdFeB magnetics material compound) has been created and done some treatment. It has been known that corrosion resistance of RBM with epoxy resin binder is higher than RBM with polyester binder (PE). Corrosion rate in variety solutions like water. Na CI, H 2 SO 4 , has proved the earlier statement. For corrosion testing of RBM in Na CI solution with concentrations 0.05 M and 0.10 M shows corrosion rate 0.18 milli inches/year (mpy) and 2.93 mpy for epoxy binder, and 4.10 mpy and 24.87 mpy for polyester binder. In order to enhance the corrosion resistance, coating of RBM with epoxy resin has been done. And it has been known that coating of RBM with epoxy resin decrease of corrosion rate almost 50%. Corrosion rate of RBM with epoxy coating in 0.15 M Na CI is 9.38 mpy, compared without coating 15.11 mpy

  5. Optimization of magnetocaloric properties of arc-melted and spark plasma-sintered LaFe{sub 11.6}Si{sub 1.4}

    Energy Technology Data Exchange (ETDEWEB)

    Shamba, P.; Morley, N.A.; Reaney, I.M.; Rainforth, W.M. [University of Sheffield, Department of Materials Science and Engineering, Sheffield (United Kingdom); Cespedes, O. [University of Leeds, School of Physics and Astronomy, Leeds (United Kingdom)

    2016-08-15

    LaFe{sub 11.6}Si{sub 1.4} alloy has been synthesized in polycrystalline form using both arc melting and spark plasma sintering (SPS). The phase formation, hysteresis loss and magnetocaloric properties of the LaFe{sub 11.6}Si{sub 1.4} alloys synthesized using the two different techniques are compared. The annealing time required to obtain the 1:13 phase is significantly reduced from 14 days (using the arc melting technique) to 30 min (using the SPS technique). The magnetic entropy change (ΔS{sub M}) for the arc-melted LaFe{sub 11.6}Si{sub 1.4} compound, obtained for a field change of 5 - 0T (decreasing field), was estimated to be 19.6 J kg{sup -1} K{sup -1}. The effective RCP at 5T of the arc-melted LaFe{sub 11.6}Si{sub 1.4} compound was determined to be 360 J kg{sup -1} which corresponds to about 88 % of that observed in Gd. A significant reduction in the hysteretic losses in the SPS LaFe{sub 11.6}Si{sub 1.4} compound was observed. The ΔS{sub M}, obtained for a field change of 5 - 0T (decreasing field), for the SPS LaFe{sub 11.6}Si{sub 1.4} compound decreases to 7.4 J kg{sup -1} K{sup -1}. The T{sub C} also shifts from 186 (arc-melted) to 230 K (SPS) and shifts the order of phase transition from first to second order, respectively. The MCE of the SPS LaFe{sub 11.6}Si{sub 1.4} compound spreads over a larger temperature range with the RCP value at 5T reaching 288 J kg{sup -1} corresponding to about 70 % of that observed in Gd. At low fields, the effective RCP values of the arc-melted and spark plasma-sintered LaFe{sub 11.6}Si{sub 1.4} compounds are comparable, thereby clearly demonstrating the potential of SPS LaFe{sub 11.6}Si{sub 1.4} compounds in low-field magnetic refrigeration applications. (orig.)

  6. 3d-metal doping (Fe,Co,Ni,Zn) of the high Tc perovskite YBa2Cu3O(7-y)

    International Nuclear Information System (INIS)

    Tarascon, J.M.; Barboux, P.; Greene, L.H.; Hull, G.W.; Bagley, B.G.

    1988-01-01

    The structural, magnetic and superconducting properties of the mixed compounds YBa 2 Cu(3-x)M(x)O(7-y) (M = Ni,Zn,Fe, and Co) are reported. Values of y, determined by titration, are found to be dependent on the nature and amount of the doping. The range of solubility is greater for the Fe and Co compounds (x = 1) than for those with Ni or Zn (x = 0.3). The undoped material is orthorhombic and remains orthorhombic after substitution for Cu by Ni or Zn, whereas a tetragonal phase is observed when Fe, Co are substituted for Cu. DC resistance and AC susceptibility measurements show that Tc is depressed from 90K (x = 0) to 45K (x = 0.2) for both the Ni- and Zn-doped compounds, and Tc is destroyed in the Fe- and Co-doped compounds when x reaches 0.4. It is suggested that a valence of two be assigned to the Ni and Zn and three to the Fe and Co ions. 8 references

  7. Unconventional emergence of elastic softening induced by magnetic fields in the unusual heavy-fermion compound PrFe sub 4 P sub 1 sub 2

    CERN Document Server

    Nakanishi, Y; Yamaguchi, T; Hazama, H; Nemoto, Y; Goto, T; Matsuda, T D; Sugawara, H; Sato, H

    2002-01-01

    Ultrasonic measurement on the filled skutterudite compound PrFe sub 4 P sub 1 sub 2 exhibits a mysterious temperature dependence of the elastic constant (C sub 1 sub 1 - C sub 1 sub 2)/2. Pronounced elastic softening at low temperatures is revived by applying a magnetic field. This fact strongly suggests the 4f-multiplet ground state of the Pr ion split by the crystalline electric field (CEF) to be a GAMMA sub 3 non-Kramers doublet. The expectation value of a quadrupole moment with GAMMA sub 3 symmetry in the CEF ground state, which leads to elastic softening at low temperature, was evaluated by theoretical fitting to the present results. This may imply that suppression of the electric quadrupole Kondo effect occurs in PrFe sub 4 P sub 1 sub 2 and the quadrupole moment becomes steady due to the application of a magnetic field. (letter to the editor)

  8. X-ray spectra, chemical bonding, and electron structure of ScM2Si2 (M = Fe, Co, Ni)

    International Nuclear Information System (INIS)

    Shcherba, I.D.; Kotur, B.Ya.

    1990-01-01

    In a study of the interaction of the components in the ternary systems Sc-M-Si (where M is a 3d transition metal) it was established that there are compounds of the empirical formula ScM 2 Si 2 (M = Fe, Co, Ni). They crystallize in two structural types, HfFe 2 Si 2 (the compound ScFe 2 Si 2 ) and CeGa 2 Al 2 (ScCo 2 Si 2 and ScNi 2 Si 2 ) (ref. 1), leading to different coordination environment of the atoms in the structures of the compounds. With the aim of investigating the electron structure and the type ofin these compounds, they authors made a systematic x-ray spectral investigation with simultaneous analysis of the crystal structures of ScM 2 Si 2

  9. Intrinsic Properties of Fe-Substituted L1(0) Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Manchanda, P; Kumar, P; Kashyap, A; Lucis, MJ; Shield, JE; Mubarok, A; Goldstein, JI; Constantinides, S; Barmak, K; Lewis, LH; Sellmyer, DJ; Skomski, R

    2013-10-01

    First-principle supercell calculations are used to determine how 3d elemental additions, especially Fe additions, modify the magnetization, exchange and anisotropy of L1(0)-ordered ferromagnets. Calculations are performed using the VASP code and partially involve configurational averaging over site disorder. Three isostructural systems are investigated: Fe-Co-Pt, Mn-Al-Fe, and transition metal-doped Fe-Ni. In all three systems the iron strongly influences the magnetic properties of these compounds, but the specific effect depends on the host. In CoPt(Fe) iron enhances the magnetization, with subtle changes in the magnetic moments that depend on the distribution of the Fe and Co atoms. The addition of Fe to MnAl is detrimental to the magnetization, because it creates antiferromagnetic exchange interactions, but it enhances the magnetic anisotropy. The replacement of 50% of Mn by Fe in MnFeAl2 enhances the anisotropy from 1.77 to 2.5 MJ/m(3). Further, the substitution of light 3d elements such as Ti, V, Cr into L1(0)-ordered FeNi is shown to substantially reduce the magnetization.

  10. N, Fe and WO3 modified TiO2 for degradation of formaldehyde

    International Nuclear Information System (INIS)

    Tong Haixia; Zhao Li; Li Dan; Zhang Xiongfei

    2011-01-01

    Graphical abstract: The undoped TiO 2 powder (T(0)) shows strong photoabsorption only at wavelengths shorter than 400 nm, and while Fe 3+ and N-doped TiO 2 nanoparticles show photoabsorption in visible region and the absorption edge shifts to a longer wavelength. WO 3 compounding also benefits the photoabsorption in visible region. Display Omitted Highlights: → The preparation of the catalysts co-doped by Fe, N and compounded by WO 3 . → The obvious sculptured 'pattern' of the catalysts doped by Fe in the SEM images. → Strengthened photoabsorption to visible light of the modified catalysts from UV-DRS analysis. - Abstract: Butyltitanate, ethanol and glacial acetic acid were chosen as titanium source, solvent and chelating agent, respectively, via a sol-gel method combined impregnation method to prepare N, Fe co-doped and WO 3 compounded photocatalyst TiO 2 powder. The synthesized products were characterized by X-ray diffraction (XRD), diffuse reflectance UV-Vis spectra (UV-DRS), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Photocatalytic degradation of formaldehyde was employed to investigate the catalytic activity. The results show that the degradation rate is 77.61% in 180 min under UV light irradiation when the concentration of N is fixed on, and the optimum proportioning ratio of n(Fe):n(W):n(Ti) is 0.5:2:100.

  11. Effect of γ-(Fe,Ni) crystal-size stabilization in Fe-Ni-B amorphous ribbon

    Science.gov (United States)

    Gorshenkov, M. V.; Glezer, A. M.; Korchuganova, O. A.; Aleev, A. A.; Shurygina, N. A.

    2017-02-01

    The effect of stabilizing crystal size in a melt-quenched amorphous Fe50Ni33B17 ribbon is described upon crystallization in a temperature range of 360-400°C. The shape, size, volume fraction, and volume density have been investigated by transmission electron microscopy and X-ray diffraction methods. The formation of an amorphous layer of the Fe50Ni29B21 compound was found by means of atomic-probe tomography at the boundary of the crystallite-amorphous phase. The stabilization of crystal sizes during annealing is due to the formation of a barrier amorphous layer that has a crystallization temperature that exceeds the crystallization temperature of the matrix amorphous alloy.

  12. Organometallic Routes into the Nanorealms of Binary Fe-Si Phases

    Directory of Open Access Journals (Sweden)

    Teddy M. Keller

    2010-02-01

    Full Text Available The Fe-Si binary system provides several iron silicides that have varied and exceptional material properties with applications in the electronic industry. The well known Fe-Si binary silicides are Fe3Si, Fe5Si3, FeSi, a-FeSi2 and b-FeSi2. While the iron-rich silicides Fe3Si and Fe5Si3 are known to be room temperature ferromagnets, the stoichiometric FeSi is the only known transition metal Kondo insulator. Furthermore, Fe5Si3 has also been demonstrated to exhibit giant magnetoresistance (GMR. The silicon-rich b-FeSi2 is a direct band gap material usable in light emitting diode (LED applications. Typically, these silicides are synthesized by traditional solid-state reactions or by ion beam-induced mixing (IBM of alternating metal and silicon layers. Alternatively, the utilization of organometallic compounds with reactive transition metal (Fe-carbon bonds has opened various routes for the preparation of these silicides and the silicon-stabilized bcc- and fcc-Fe phases contained in the Fe-Si binary phase diagram. The unique interfacial interactions of carbon with the Fe and Si components have resulted in the preferential formation of nanoscale versions of these materials. This review will discuss such reactions.

  13. Crystal and magnetic structures of CaCu3Fe4O12 and LaCu3Fe4O12: distinct charge transitions of unusual high valence Fe

    International Nuclear Information System (INIS)

    Shimakawa, Yuichi

    2015-01-01

    New 134-type perovskites, CaCu 3 Fe 4 O 12 (CCFO) and LaCu 3 Fe 4 O 12 (LCFO), were prepared by means of high-pressure synthesis. The compounds contain unusual high valence Fe 4+ in CCFO and Fe 3.75+ in LCFO at high temperatures. With decreasing temperature, the instabilities of the high valence states of Fe are relieved by distinct charge transitions, which are charge disproportionation (4Fe 4+   →  2Fe 3+   +  2Fe 5+ ) in CCFO and intermetallic charge transfer (3Cu 2+   +  4Fe 3.75+   →  3Cu 3+   +  4Fe 3+ ) in LCFO. Crystal structure analysis with synchrotron x-ray diffraction and magnetic structure analysis with neutron diffraction revealed the nature of the transitions. Although the two behaviors look completely different from each other in simple ionic models, they can both be explained by the localization of ligand holes, which are produced by the strong hybridization of low-lying Fe-d and oxygen p orbitals in the oxides. The ligand holes in the charge disproportionated CCFO are localized at the Fe–O sites alternately (4d 5 L  →  2d 5   +  2d 5 L 2 ) and the ligand holes in the charge transferred LCFO are localized at the Cu–O sites (3d 9   +  4d 5 L 0.75   →  3d 9 L  +  4d 5 ). (review)

  14. Synthesis and magnetic hyperthermia studies on high susceptible Fe1-xMgxFe2O4 superparamagnetic nanospheres

    Science.gov (United States)

    Manohar, A.; Krishnamoorthi, C.

    2017-12-01

    Majority studies on magnetic hyperthermia properties were carried out by modifying the saturation mass magnetization (Ms) of the samples. Here efforts were made to enhance the specific heat generation rate (SHGR) of single domain superparamagnetic (SP) material by modifying its magnetic susceptibility. Well crystallined, inverse spinel structured and close to monosize Fe1-xMgxFe2O4 (x = 0, 0.1, 0.2, 0.3, 0.4, & 0.5) compounds with nanosphere geometry (diameter 10 nm) were synthesized by solvothermal reflux method at ≈ 300 °C . In the literature it is reported that magnesium ferrites synthesized at high temperatures yield mixed (normal & inverse) spinel structures. The inverse spinel structure was confirmed by X-ray powder diffraction (XRPD), lattice vibrations and magnetic characteristics of the compounds. The Ms of the compounds decrease with increase of substituent Mg2+ concentration. Under high excitation energy the inter-valance charge transfer whereas under low excitation energy the intra-valance charge transfer process were predominant. The as-synthesized nanospheres were encapsulated by hydrophobic oleic acid and were exchanged by hydrophilic poly(acrylic acid) by chemical exchange process. Estimated magnetic hyperthermia power or SHGR of the x = 0, 0.3 & 0.5 were 11, 11.4 & 22.4 W per gram of respective compounds, respectively, under 63.4 kA m-1 field amplitude and 126 kHz frequency. The SHGR enhances with Mg2+ concentration though its Ms reduces and is attributed to reduced spin-orbital coupling in the compounds with enhanced Mg2+ concentration. This may pave a new way to develop magnetic hyperthermia material by modifying magnetic susceptibility of the compounds against to the reported Ms modification approach. The obtained high SHGR of the biocompatible compounds could be used in magnetic hyperthermia applications in biomedical field.

  15. Phase formation in Zr/Fe multilayers during Kr ion irradiation

    International Nuclear Information System (INIS)

    Motta, A. T.

    1998-01-01

    A detailed study has been conducted of the effect of Kr ion irradiation on phase formation in Zr-Fe metallic multilayers, using the Intermediate Voltage Electron Microscopy (IVEM) at Argonne National Laboratory. Metallic multilayers were prepared with different overall compositions (near 50-50 and Fe-rich), and with different wavelengths (repetition thicknesses). These samples were irradiated with 300 keV Kr ions at various temperatures to investigate the final products, as well as the kinetics of phase formation. For the shorter wavelength samples, the final product was in all cases an amorphous Zr-Fe phase, in combination with Fe, while specially for the larger wavelength samples, in the Fe-rich samples the intermetallic compounds ZrFe 2 and Zr 3 Fe were formed in addition to the amorphous phase. The dose to full reaction decreases with temperature, and with wavelength in a manner consistent with a diffusion-controlled reaction

  16. High field ESR study of the pi-d interaction effect in beta-(BDA-TTP)2MCl4 (M=Fe, Ga)

    Science.gov (United States)

    Tokumoto, Takahisa; Vantol, J.; Brunel, L.-C.; Choi, E. S.; Brooks, J. S.; Kaihatsu, T.; Akutsu, H.; Yamada, J.

    2007-03-01

    Novel magnetic organic conductors with pi-d interaction have commanded attention since the discovery of field induced superconductivity. One of them, beta-(BDA-TTP)2FeCl4, has alternating donor molecules and quasi 2D electrical properties. Previous studies of electrical and magnetic properties show an M-I transition at 120K and an AF transition at TN=8.5K, suggesting an exchange interaction between the conduction electrons and the Fe^3+ d-electrons. The properties of beta-(BDA-TTP)2GaCl4 are similar with exception of the absence of the AF transition, which is apparently due to the absence of pi-d exchange interaction. We report angular/temperature dependent 240GHz quasi optical ESR measurements on both compounds to probe the magnetic properties. The Ga compound signals follow the donor molecule structure, and show no magnetic order at any temperature. The Fe compound signals are quite different from the Ga compound, and exhibit AF behavior below TN. The difference of Fe and Ga compounds will be discussed in terms of the interaction between localized and itinerant magnetic moments.

  17. First principles calculations of the electronic structure and magnetic properties of Y(Fe,M)9.2 and Y(Fe,M)9.2C (M= Si, Ga, Zr)

    Science.gov (United States)

    Tian, Guang; Zha, Liang; Yang, Wenyun; Qiao, Guanyi; Wang, Changsheng; Yang, Yingchang; Yang, Jinbo

    2018-06-01

    The preferential site substitution of the Fe by Si, Ga and Zr in the Y(Fe,M)9.2 and Y(Fe,M)9.2C compounds, and the doping effects on the magnetic properties have been studied by the first-principles calculations. It is found that the doping of the Si or Zr can improve the thermodynamic stability of the 1:9 phase, while the substitution of the Fe by Ga makes it unstable. Si atom tends to enter the 3g crystal site and Zr prefers to occupy the 2e site when Y(Fe,M)9.2 and their carbides are synthesized. Although the substitution of the Fe by Si and Zr will reduce the total magnetic moments of the YFe9.2 and their carbides, the volumetric and the d-band narrowing effects caused by the doping can still modify the electron density distributions of the Fe near the Fermi level, improving the magnetic ordering temperature of the non-carbonated compound YFe9.2. The calculated magnetic ordering temperatures of Y(Fe,M)9.2C decrease with the increasing content of the doping elements M due to the stronger hybridization of the d bands in the carbides. For the rare-earth(RE) iron based intermetallics REFe9.2 with the TbCu7-type structure, it is suggested that Zr is able to stabilize the phase and enhance the magnetic ordering temperature, indicating the possible further application in the field of permanent magnets, which has not been reported before.

  18. Arsenic mobility and bioavailability in paddy soil under iron compound amendments at different growth stages of rice.

    Science.gov (United States)

    Yu, Huan-Yun; Wang, Xiangqin; Li, Fangbai; Li, Bin; Liu, Chuanping; Wang, Qi; Lei, Jing

    2017-05-01

    Iron (Fe)-based solids can reduce arsenic (As) mobility and bioavailability in soils, which has been well recognized. However, to our knowledge, there are few studies on As uptake at different growth stages of rice under Fe compound amendments. In addition, the formation of Fe plaques at different growth stages of rice has also been rarely reported. Therefore, the present study was undertaken to investigate As mobility and bioavailability in paddy soil under Fe compound amendments throughout the whole growth stage of rice plants. Amendments of poorly crystalline Fe oxides (PC-Fe), FeCl 2 +NaNO 3 and FeCl 2 reduced grain As by 54% ± 3.0%, 52% ± 3.0% and 46% ± 17%, respectively, compared with that of the non-amended control. The filling stage was suggested to be the key stage to take measures to reduce As uptake. At this stage, all soil amendments significantly reduced As accumulation in rice plants. At the maturation stage, PC-Fe amendment significantly reduced mobile pools and increased immobile pools of soil As. Besides, PC-Fe treatment promoted the transformation of Fe fractions from dissolved Fe to adsorbed, poorly crystalline and free Fe oxides. Moreover, significant positive correlations between soil Fe fractions and As fractions were found. Accordingly, we hypothesized that Fe compound amendments might affect the concentration distribution of Fe fractions first and then affect As fractionation in soil and its bioavailability to rice plants indirectly. The formation of Fe plaques varied with growth stages and different treatments. Significantly negative correlations between mobile pools of As and Fe or As in Fe plaques indicated that Fe plaques could immobilize mobile As in soils and thus affect As bioavailability. Overall, the effect of the soil amendments on reduction of As uptake varied with growth stages and different treatments, and further research on the key stage for reducing As uptake is still required. Copyright © 2017 Elsevier Ltd. All

  19. Bibliography about silicon non-organic fluorine compounds

    International Nuclear Information System (INIS)

    Carles, M.

    1963-01-01

    This bibliography is made from Professor I.G. Ryss' book published in Moscow in 1956, translated in English under the title 'The chemistry of fluorine and its inorganic compounds' (Translation series. AEC tr 3927, Pt 1 and 2), and completed with the data found in the 'Chemical Abstracts' of the years 1946 to 1962 [fr

  20. The new Fe-based superconductors

    International Nuclear Information System (INIS)

    Mao, Zhiqiang

    2011-01-01

    The discovery of unconventional superconductivity in doped iron pnictides has ushered in a new era of high temperature superconductivity. The superconductivity of these materials occurs in close proximity to magnetic instability; superconductivity is achieved by suppressing a long-range antiferromagnetic (AFM) order through charge carrier doping or pressure. In this talk, I will first give a brief overview of the phase diagrams of iron-based superconductors, and then talk about our recent research on iron chalcogenide Fe 1+y (Te 1-x Se x ) superconductors, which is structurally the simplest of the Fe-based superconductors. Although the Fermi surface of iron chalcogenides is similar to iron pnictides, the parent compound Fe 1+y Te exhibits AFM order with in-plane magnetic wave-vector (π, 0). This contrasts the pnictide parent compounds where the magnetic order has an in-plane magnetic wave-vector (π, π) that connects hole and electron parts of the Fermi surface. Despite these differences, both the pnictide and chalcogenide Fe-superconductors exhibit superconducting spin resonances around (π, π), suggesting a common symmetry for their superconducting order parameter. A central question in this burgeoning field is therefore how (π, π) superconductivity can emerge from a (π, 0) magnetic instability. I will address this issue in my talk. I will show the phase diagram of electronic and magnetic properties we recently established for this system and discuss the relationship between magnetic coupling and electronic properties. Our results reveal that the magnetic soft mode evolving from the (π, 0)-type magnetic long-range order is associated with weak charge carrier localization. Bulk superconductivity occurs only as magnetic correlations near (π, 0) are strongly suppressed and the magnetic mode at (π, π) becomes dominant; this suggests a common magnetic origin for superconductivity in iron chalcogenide and pnictide superconductors. (author)

  1. Giant Enhancement of Magnetostrictive Response in Directionally-Solidified Fe83Ga17Erx Compounds

    Directory of Open Access Journals (Sweden)

    Radhika Barua

    2018-06-01

    Full Text Available We report, for the first time, correlations between crystal structure, microstructure and magnetofunctional response in directionally solidified [110]-textured Fe83Ga17Erx (0 < x < 1.2 alloys. The morphology of the doped samples consists of columnar grains, mainly composed of a matrix phase and precipitates of a secondary phase deposited along the grain boundary region. An enhancement of more than ~275% from ~45 to 170 ppm is observed in the saturation magnetostriction value (λs of Fe83Ga17Erx alloys with the introduction of small amounts of Er. Moreover, it was noted that the low field derivative of magnetostriction with respect to an applied magnetic field (i.e., dλs/dHapp for Happ up to 1000 Oe increases by ~230% with Er doping (dλs/dHapp,FeGa= 0.045 ppm/Oe; dλs/dHapp,FeGaEr= 0.15 ppm/Oe. The enhanced magnetostrictive response of the Fe83Ga17Erx alloys is ascribed to an amalgamation of microstructural and electronic factors, namely: (i improved grain orientation and local strain effects due to deposition of Er in the intergranular region; and (ii strong local magnetocrystalline anisotropy, due to the highly anisotropic localized nature of the 4f electronic charge distribution of the Er atom. Overall, this work provides guidelines for further improving galfenol-based materials systems for diverse applications in the power and energy sector.

  2. Spin Polarization Inversion at Benzene-Absorbed Fe4N Surface

    KAUST Repository

    Zhang, Qian; Mi, Wenbo; Wang, Xiaocha; Wang, Xuhui

    2015-01-01

    We report a first-principle study on electronic structure and simulation of the spin-polarized scanning tunneling microscopy graphic of a benzene/Fe4N interface. Fe4N is a compound ferromagnet suitable for many spintronic applications. We found that, depending on the particular termination schemes and interface configurations, the spin polarization on the benzene surface shows a rich variety of properties ranging from cosine-type oscillation to polarization inversion. Spin-polarization inversion above benzene is resulting from the hybridizations between C pz and the out-of-plane d orbitals of Fe atom.

  3. Spin Polarization Inversion at Benzene-Absorbed Fe4N Surface

    KAUST Repository

    Zhang, Qian

    2015-05-27

    We report a first-principle study on electronic structure and simulation of the spin-polarized scanning tunneling microscopy graphic of a benzene/Fe4N interface. Fe4N is a compound ferromagnet suitable for many spintronic applications. We found that, depending on the particular termination schemes and interface configurations, the spin polarization on the benzene surface shows a rich variety of properties ranging from cosine-type oscillation to polarization inversion. Spin-polarization inversion above benzene is resulting from the hybridizations between C pz and the out-of-plane d orbitals of Fe atom.

  4. 32 CFR 644.62 - Title evidence.

    Science.gov (United States)

    2010-07-01

    ... HANDBOOK Acquisition Procurement of Title Evidence, Title Clearance, and Closings § 644.62 Title evidence... and their charter to issue the same. They must also be financially sound and be willing and able to...

  5. Title to mining properties

    International Nuclear Information System (INIS)

    Crouch, K.M.

    1976-01-01

    The requirements of the law which must be met in order to create title to an unpatented mining claim and the procedures which should be followed when an attempt is made to determine the title to the claim is acceptable are reviewed

  6. Conductivity and electrochemical characterization of PrFe1-xNixO3-δ at high temperature

    DEFF Research Database (Denmark)

    Hashimoto, Shin-Ichi; Kammer Hansen, Kent; Poulsen, Finn Willy

    2007-01-01

    PrFe(1-x)NixO(3)- (x=0.4-0.6) compounds were synthesized and characterized by powder XRD, electrical conductivity and electrochemical impedance spectroscopy on point electrodes on a Ce0.9Gd0.1O2-delta (CGO10) electrolyte. As a reference, the electrochemical performance of LaFe(0.4)AM(0.6)O(3-delta......) was also measured. The main phase in the PrFe1-xNixO3-delta series was perovskite-type structure and belonged to the orthorhombic crystal system. The conductivities are fairly high, e.g. around 220 S cm(-1) at 873 K for the x = 0.4 compound. The electrochemical performance of the PrFe(1-x)NixO(3-delta...

  7. Test of level density models from reactions of Li6 on Fe58 and Li7 on Fe57

    Science.gov (United States)

    Oginni, B. M.; Grimes, S. M.; Voinov, A. V.; Adekola, A. S.; Brune, C. R.; Carter, D. E.; Heinen, Z.; Jacobs, D.; Massey, T. N.; O'Donnell, J. E.; Schiller, A.

    2009-09-01

    The reactions of Li6 on Fe58 and Li7 on Fe57 have been studied at 15 MeV beam energy. These two reactions produce the same compound nucleus, Cu64. The charged particle spectra were measured at backward angles. The data obtained have been compared with Hauser-Feshbach model calculations. The level density parameters of Ni63 and Co60 have been obtained from the particle evaporation spectra. We also find contributions from the break up of the lithium projectiles to the low energy region of the α spectra.

  8. Preparation and photo-catalytic activities of FeOOH/ZnO/MMT composite

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yao, E-mail: zy19830808@163.com [College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Liu, Fusheng; Yu, Shitao [College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China)

    2015-11-15

    Highlights: • The montmorillonite was used as the carrier for the synthesis of FeOOH nano-material and FeOOH/ZnO nano-material. • TEM was used to study the structure of the two nano-materials with the composite structure of goethite and wurtzite. • TEM was used to demonstrate FeOOH/ZnO nano-material can formed with the appropriate interface: wurtzite-(1 0 1)/(1 1 1)-goethite. • There were some coupling effect between FeOOH and ZnO, which can improve the photo-catalytic activities of FeOOH. • According to FTIR and TOC, PCP was degraded to aromatic ketone compounds and then to H{sub 2}O, CO{sub 2}, HCl. - Abstract: Montmorillonite (MMT) was used as the carrier for synthesis of FeOOH and FeOOH/ZnO nano-material. FeOOH and FeOOH/ZnO were synthesized by the aqueous solutions of Fe(NO{sub 3}){sub 3}–HNO{sub 3} and Zn(NO{sub 3}){sub 2}–NaOH/Fe(NO{sub 3}){sub 3}–HNO{sub 3} with the carrier of montmorillonite respectively. Transmission electron-microscopy (TEM) and X-ray diffraction (XRD) were used to study the morphology form and structure of the nano-materials. TEM was also used to demonstrate that FeOOH/ZnO can be formed with the appropriate interface. According to UV–vis absorption spectra, FeOOH/ZnO has a better response to visible light than FeOOH and ZnO, which indicates there is some coupling effect between FeOOH and ZnO. Pentachlorophenol (PCP) was used as a representative organic pollutant to evaluate the photo-catalytic efficiency of the FeOOH/ZnO and FeOOH catalysts in visible light (λ > 400 nm). The photo-catalytic efficiency of FeOOH/ZnO/MMT is better than FeOOH/MMT. According to FTIR, changes of pH and TOC, the degradation mechanism was also discussed. PCP was degraded to aromatic ketone and chloro-hydrocarbon compounds and then to H{sub 2}O, CO{sub 2} and HCl.

  9. Synthesis and characterization of a Ruddlesden-Popper compound: Sr3FeMoO7

    International Nuclear Information System (INIS)

    Li Zhaofei; Li Guobao; Sun Junliang; You Liping; Loong, Chun-K.; Wang Yingxia; Liao Fuhui; Lin Jianhua

    2005-01-01

    A powder sample of Sr 3 FeMoO 7 was synthesized by solid-state reaction in reduced atmosphere (5% H 2 /Ar). At room temperature, Sr 3 FeMoO 7 crystallizes in a typical Ruddlesden-Popper (n=2) structure in the space group I4/mmm, a=3.9309(2)A and c=20.435(2)A. The structure refinement indicates that the Fe and Mo ions are randomly distributed in a single B-site with small fraction of B-site and oxygen vacancies. At low temperature, long-range magnetic interaction was observed. The antiferromagnetic magnetic interaction can be described with a large unit cell, a m =b m =2a n and c m =c n , in the magnetic space group An'

  10. FeBr3-catalyzed dibromination of alkenes and alkynes

    Institute of Scientific and Technical Information of China (English)

    Yun Fa Zheng; Jian Yu; Guo Bing Yan; Xu Li; Song Luo

    2011-01-01

    The dibromination of alkenes and alkynes with bromosuccinimide and sodium bromide catalyzed by FeBr3 under mild conditions has been developed. The trans-dibromo compounds were exclusively obtained with excellent yields.

  11. Structural, mechanical, electronic and magnetic properties of a new series of quaternary Heusler alloys CoFeMnZ (Z=Si, As, Sb): A first-principle study

    Energy Technology Data Exchange (ETDEWEB)

    Elahmar, M.H.; Rached, H.; Rached, D. [Laboratoire des Matériaux Magnétiques, Faculté des Sciences, Université Djillali Liabès de SidiBel-Abbès, SidiBel-Abbès 22000 (Algeria); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 (Algeria); Murtaza, G. [Materials Modeling Lab, Department of Physics, Islamia College Peshawar, KPK (Pakistan); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Ahmed, W.K. [ERU, College of Engineering, United Arab Emirates University, Al Ain, Abu Dhabi (United Arab Emirates)

    2015-11-01

    The structural, mechanical, electronic and magnetic properties of the series of Heusler alloys CoFeMnZ (Z=Si, As, and Sb) have been investigated theoretically. The objective is to seek for stable half-metallic ferromagnets materials with Curie temperatures higher than room temperature. The series of CoFeMnZ (Z=Si, As and Sb) is found to exhibit half-metallic ferromagnetism with high magnetic moment and the localized moment in these magnetic compounds resides at the Mn atom. It has been observed that all our compounds have high Curie temperatures with high spin polarizations. - Highlights: • Density functional calculations for CoFeMnZ (Z=Si, As, Sb) compounds are performed. • Half-metallic ferromagnetism in CoFeMnZ (Z=Si, As, Sb) compounds is established. • The magnetic and mechanical properties for CoFeMnZ (Z=As, Sb) are studied for the first time. • The studied compounds possess high Curie temperatures with high spin polarizations.

  12. Influence of a niobium coating on sulfidation resistance of FeCr and FeCrY alloys; Influencia de um revestimento de niobio sobre a resistencia a sulfetacao das ligas FeCr e FeCrY

    Energy Technology Data Exchange (ETDEWEB)

    Geribola, Gulherme Altomari

    2014-07-01

    Niobium and niobium based alloys are currently used in many industrial applications because they offer excellent resistance to degradation in various corrosive environments. These media include gaseous atmospheres at high temperatures such as those found in existing coal gasifying plants in power plants for energy generation. These atmospheres are complex gas mixtures that contain sulfur and oxygen, among other compounds. Sulphides are thermodynamically less stable, have lower melting points and often have larger deviations from stoichiometry compared to the corresponding oxides. Although there are studies regarding the use of refractory metals in high temperature sulphidizing atmospheres, the use of niobium compounds has not been adequately evaluated and there is very little studies available in the literature about its use as a protective coating. The aim of this study was to evaluate the effect of a niobium film, deposited by magnetron sputtering on the isothermal sulphidation behavior of Fe-20Cr and Fe-20Cr-1Y alloys. The sulphidation tests were carried out at 500, 600 and 700 deg C for 2h in H{sub 2}/2% H2S atmosphere. The sulphidation resistance was determined by mass gain per unit area. The sulphidation behavior of the coated and uncoated alloys was similar at 500 deg C, and none of the alloys scaled. At 700 deg C FeCr alloy scaled in the form of a fine powder, while the reaction product formed on the alloy FeCrY scaled in the form of plates. The effect of niobium became pronounced at 700 deg C. The reaction product layer formed on the coated alloy was thinner and more plastic than that formed on the uncoated alloy. The mass gain per unit area of the coated alloys decreased significantly and they did not scaled. (author)

  13. Formation of SmFe5(0001) ordered alloy thin films on Cu(111) single-crystal underlayers

    International Nuclear Information System (INIS)

    Yabuhara, Osamu; Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki; Kirino, Fumiyoshi

    2010-01-01

    SmFe 5 (0001) single-crystal thin films are prepared by molecular beam epitaxy employing Cu(111) single-crystal underlayers on MgO(111) substrates. The Cu atoms diffuse into the Sm-Fe layer and substitute the Fe sites in SmFe 5 structure forming an alloy compound of Sm(Fe,Cu) 5 . The Sm(Fe,Cu) 5 film is more Cu enriched with increasing the substrate temperature. The Cu underlayer plays an important role in assisting the formation of the ordered phase.

  14. Magnesium doping on brownmillerite Ca2FeAlO5

    International Nuclear Information System (INIS)

    Malveiro, J.; Ramos, T.; Ferreira, L.P.; Waerenborgh, J.C.; Nunes, M.R.; Godinho, M.; Carvalho, M.D.

    2007-01-01

    Ca 2 FeAl 1- x Mg x O 5 (x=0, 0.05 and 0.1) compounds adopting the brownmillerite-type structure were prepared by a self-combustion route using two different fuels. Characterisation was performed using X-ray powder diffraction, Moessbauer spectroscopy, magnetisation measurements, chemical analysis, scanning electron microscopy and 4-point dc conductivity measurements. Global results indicate that the solubility limit was reached for x=0.1. An antiferromagnetic behaviour was detected for all studied compositions, with magnetic ordering temperatures of 340 and 290 K for x=0 and 0.05, respectively. Mg doping increases the number of iron cations in tetrahedral sites, which induces magnetisation enhancement at low temperatures through the coupling between octahedral iron cations in different octahedral planes. The compounds exhibit semiconductor behaviour and Mg 2+ doping yields a significant enhancement of the total conductivity, which can be essentially attributed to the presence of Fe 4+ ions. - Graphical abstract: Ca 2 FeAl 1- x Mg x O 5 (x=0, 0.05, 0.1) compounds with the brownmillerite structure were prepared and characterised. The paramagnetic Moessbauer spectra presented were obtained at T=363 K (x=0); T=297 K (x=0.05) and T=353 K (x=0.1)

  15. Exchange coupling behavior in bimagnetic CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Leite, G.C.P. [Instituto de Fisica, Universidade Federal de Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Chagas, E.F., E-mail: efchagas@fisica.ufmt.br [Instituto de Fisica, Universidade Federal de Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Pereira, R.; Prado, R.J. [Instituto de Fisica, Universidade Federal de Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Terezo, A.J. [Departamento de Quimica, Universidade Federal do Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Alzamora, M.; Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Fisicas, Rua Xavier Sigaud 150 Urca, Rio de Janeiro (Brazil)

    2012-09-15

    In this work we report a study of the magnetic behavior of ferrimagnetic oxide CoFe{sub 2}O{sub 4} and ferrimagnetic oxide/ferromagnetic metal CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite. The latter compound is a good system to study hard ferrimagnet/soft ferromagnet exchange coupled. Two steps were followed to synthesize the bimagnetic CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite: (i) first, preparation of CoFe{sub 2}O{sub 4} nanoparticles using a simple hydrothermal method, and (ii) second, reduction reaction of cobalt ferrite nanoparticles using activated charcoal in inert atmosphere and high temperature. The phase structures, particle sizes, morphology, and magnetic properties of CoFe{sub 2}O{sub 4} nanoparticles were investigated by X-Ray diffraction (XRD), Mossbauer spectroscopy (MS), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) with applied field up to 3.0 kOe at room temperature and 50 K. The mean diameter of CoFe{sub 2}O{sub 4} particles is about 16 nm. Mossbauer spectra revealed two sites for Fe{sup 3+}. One site is related to Fe in an octahedral coordination and the other one to the Fe{sup 3+} in a tetrahedral coordination, as expected for a spinel crystal structure of CoFe{sub 2}O{sub 4}. TEM measurements of nanocomposite showed the formation of a thin shell of CoFe{sub 2} on the cobalt ferrite and indicate that the nanoparticles increase to about 100 nm. The magnetization of the nanocomposite showed a hysteresis loop that is characteristic of exchange coupled systems. A maximum energy product (BH){sub max} of 1.22 MGOe was achieved at room temperature for CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposites, which is about 115% higher than the value obtained for CoFe{sub 2}O{sub 4} precursor. The exchange coupling interaction and the enhancement of product (BH){sub max} in nanocomposite CoFe{sub 2}O{sub 4}/CoFe{sub 2} are discussed. - Highlights: Black-Right-Pointing-Pointer CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite

  16. Crystal growth iron based pnictide compounds; Kristallzuechtung eisenbasierter Pniktidverbindungen

    Energy Technology Data Exchange (ETDEWEB)

    Nacke, Claudia

    2012-11-15

    The present work is concerned with selected crystal growth method for producing iron-based superconductors. The first part of this work introduces significant results of the crystal growth of BaFe{sub 2}As{sub 2} and the cobalt-substituted compound Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} with x{sub Nom} = 0.025, 0.05, 0.07, 0.10 and 0.20. For this purpose a test procedure for the vertical Bridgman method was developed. The second part of this work contains substantial results for growing a crystal of LiFeAs and the nickel-substituted compound Li{sub 1-δ}Fe{sub 1-x}Ni{sub x}As with x{sub Nom} = 0.015, 0.025, 0.05, 0.06, 0.075 and 0.10. For this purpose a test procedure for the melt flow process has been developed successfully. [German] Die vorliegende Arbeit befasst sich mit ausgewaehlten Kristallzuechtungsverfahren zur Herstellung eisenbasierter Supraleiter. Der erste Teil dieser Arbeit fuehrt wesentliche Ergebnisse der Kristallzuechtung von BaFe{sub 2}As{sub 2} sowie der Cobalt-substituierten Verbindung Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} mit x{sub Nom} =0.025, 0.05, 0.07, 0.10 und 0.20 auf. Hierzu wurde eine Versuchsdurchfuehrung fuer das vertikale Bridgman-Verfahren konzipiert, mit welcher erfolgreich Kristalle dieser Zusammensetzungen gezuechtet wurden. Der zweite Teil dieser Arbeit enthaelt wesentliche Ergebnisse zur Kristallzuechtung von LiFeAs sowie der Nickel-substituierten Verbindung Li{sub 1-δ}Fe{sub 1-x}Ni{sub x}As mit x{sub Nom} = 0.015, 0.025, 0.05, 0.06, 0.075 und 0.10. Hierfuer wurde erfolgreich eine Versuchsdurchfuehrung fuer das Schmelzfluss-Verfahren entwickelt.

  17. Application of UV-irradiated Fe(III)-nitrilotriacetic acid (UV-Fe(III)NTA) and UV-NTA-Fenton systems to degrade model and natural occurring naphthenic acids.

    Science.gov (United States)

    Zhang, Ying; Chelme-Ayala, Pamela; Klamerth, Nikolaus; Gamal El-Din, Mohamed

    2017-07-01

    Naphthenic acids (NAs) are a highly complex mixture of organic compounds naturally present in bitumen and identified as the primary toxic constituent of oil sands process-affected water (OSPW). This work investigated the degradation of cyclohexanoic acid (CHA), a model NA compound, and natural occurring NAs during the UV photolysis of Fe(III)-nitrilotriacetic acid (UV-Fe(III)NTA) and UV-NTA-Fenton processes. The results indicated that in the UV-Fe(III)NTA process at pH 8, the CHA removal increased with increasing NTA dose (0.18, 0.36 and 0.72 mM), while it was independent of the Fe(III) dose (0.09, 0.18 and 0.36 mM). Moreover, the three Fe concentrations had no influence on the photolysis of the Fe(III)NTA complex. The main responsible species for the CHA degradation was hydroxyl radical (OH), and the role of dissolved O 2 in the OH generation was found to be negligible. Real OSPW was treated with the UV-Fe(III)NTA and UV-NTA-Fenton advanced oxidation processes (AOPs). The removals of classical NAs (O 2 -NAs), oxidized NAs with one additional oxygen atom (O 3 -NAs) and with two additional oxygen atoms (O 4 -NAs) were 44.5%, 21.3%, and 25.2% in the UV-Fe(III)NTA process, respectively, and 98.4%, 86.0%, and 81.0% in the UV-NTA-Fenton process, respectively. There was no influence of O 2 on the NA removal in these two processes. The results also confirmed the high reactivity of the O 2 -NA species with more carbons and increasing number of rings or double bond equivalents. This work opens a new window for the possible treatment of OSPW at natural pH using these AOPs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Study of thermal spin crossover in [Fe(II)(isoxazole)(6)](BF4)(2) with Mossbauer spectroscopy

    NARCIS (Netherlands)

    Bhattacharjee, A.; van Koningsbruggen, P. J.; Hibbs, W.; Miller, Joel S.; Guetlich, P.

    2007-01-01

    Fe-57 Mossbauer spectroscopy of the mononuclear [Fe( II)( isoxazole)(6)]( BF4)(2) compound has been studied to reveal the thermal spin crossover of Fe( II) between low- spin ( S = 0) and high- spin ( S = 2) states. A temperature-dependent spin transition curve has been constructed with the least-

  19. (Z-3-(4-Bromoanilino-1-ferrocenylbut-2-en-1-one

    Directory of Open Access Journals (Sweden)

    C. Manzur

    2010-12-01

    Full Text Available In the title compound, [Fe(C5H5(C15H13BrNO], formed from the reaction of ferrocenoylacetone and 4-bromoaniline, the molecular structure is stabilized by an intramolecular N—H...O hydrogen bond between the amine and carbonyl groups.

  20. Mechanism of forming interfacial intermetallic compounds at interface for solid state diffusion bonding of dissimilar materials

    International Nuclear Information System (INIS)

    He, P.; Liu, D.

    2006-01-01

    The formation of brittle intermetallic compounds at the interfaces of diffusion bonds is the main cause which leads to poor bond strength. Therefore, it is very important to study and establish the formation and growth model of intermetallic compounds at the interfaces for the control process of diffusion bonding. In this paper, according to the diffusion kinetics and the thermodynamics, the principle of formation of intermetallic compounds at interfaces in the multi-component diffusion couple, the flux-energy principle, is put forward. In the light of diffusion theory, the formation capacity of the phase at the interfaces is determined by specific properties of the composition in the diffusion couple and the composition ratio of the formed phase is in agreement with the diffusion flux. In accordance with the flux-energy principle, the microstructure of the Ni/TC4 interface is Ni/TiNi 3 /TiNi/Ti 2 Ni/TC4, the microstructure of the TC4/00Cr18Ni9Ti interface is 00Cr18Ni9Ti/TiFe 2 /TiFe/Ti 2 Fe/TC4, and the microstructure of the TiAl/40Cr interface is 40Cr/TiC/Ti 3 Al + FeAl + FeAl 2 /TiAl. Multi-intermetallic compounds with the equivalent flux-energy can be formed at the interfaces at the same time

  1. INIS: Authority list for journal titles

    International Nuclear Information System (INIS)

    2005-01-01

    This is the 31st revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). This list is published annually and includes the titles of all journals which have contained articles submitted to INIS at the time of publication. The current list contains 13,104 journal titles, 2,078 regularly scanned journals and 561 key journals. It was last updated in February 2005. The purpose of this report is to provide descriptive cataloguers with a standard entry for the full title of a journal. In addition to the full journal title, the ISSN (International Standard Serial Number), administered by the ISSN International Centre, Paris, France, and/or CODEN, assigned by Chemical Abstracts Service, USA, are given in this manual. In order to help the user find titles easily, the list is arranged in six parts, followed by summary statistics: In Part I, all key journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part II, all key journals are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. In Part III, all journals that are regularly scanned by INIS Centers are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part IV, all journals that are regularly scanned by INIS Centers are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. In Part V, all journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part VI, all journals are sorted alphabetically under their title. The name of the

  2. INIS: Authority list for journal titles

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-03-01

    This is the 31st revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). This list is published annually and includes the titles of all journals which have contained articles submitted to INIS at the time of publication. The current list contains 13,104 journal titles, 2,078 regularly scanned journals and 561 key journals. It was last updated in February 2005. The purpose of this report is to provide descriptive cataloguers with a standard entry for the full title of a journal. In addition to the full journal title, the ISSN (International Standard Serial Number), administered by the ISSN International Centre, Paris, France, and/or CODEN, assigned by Chemical Abstracts Service, USA, are given in this manual. In order to help the user find titles easily, the list is arranged in six parts, followed by summary statistics: In Part I, all key journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part II, all key journals are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. In Part III, all journals that are regularly scanned by INIS Centers are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part IV, all journals that are regularly scanned by INIS Centers are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. In Part V, all journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part VI, all journals are sorted alphabetically under their title. The name of the

  3. INIS: Authority list for journal titles

    International Nuclear Information System (INIS)

    2006-01-01

    This is the 32nd revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). This list is published annually and includes the titles of all journals which have contained articles submitted to INIS at the time of publication. The current list contains 13,231 journal titles, 2,125 regularly scanned journals and 555 key journals. It was last updated in February 2006. The purpose of this report is to provide descriptive cataloguers with a standard entry for the full title of a journal. In addition to the full journal title, the ISSN (International Standard Serial Number), administered by the ISSN International Centre, Paris, France, and/or CODEN, assigned by Chemical Abstracts Service, USA, are given in this manual. In order to help the user find titles easily, the list is arranged in six parts, followed by summary statistics: In Part I, all key journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part II, all key journals are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. In Part III, all journals that are regularly scanned by INIS Centres are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part IV, all journals that are regularly scanned by INIS Centres are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. In Part V, all journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part VI, all journals are sorted alphabetically under their title. The name of the

  4. Temperature-dependent striped antiferromagnetism of LaFeAsO in a Green's function approach

    International Nuclear Information System (INIS)

    Liu Guibin; Liu Banggui

    2009-01-01

    We use a Green's function method to study the temperature-dependent average moment and magnetic phase-transition temperature of the striped antiferromagnetism of LaFeAsO, and other similar compounds, as the parents of FeAs-based superconductors. We consider the nearest and the next-nearest couplings in the FeAs layer, and the nearest coupling for inter-layer spin interaction. The dependence of the transition temperature T N and the zero-temperature average spin on the interaction constants is investigated. We obtain an analytical expression for T N and determine our temperature-dependent average spin from zero temperature to T N in terms of unified self-consistent equations. For LaFeAsO, we obtain a reasonable estimation of the coupling interactions with the experimental transition temperature T N = 138 K. Our results also show that a non-zero antiferromagnetic (AFM) inter-layer coupling is essential for the existence of a non-zero T N , and the many-body AFM fluctuations reduce substantially the low-temperature magnetic moment per Fe towards the experimental value. Our Green's function approach can be used for other FeAs-based parent compounds and these results should be useful to understand the physical properties of FeAs-based superconductors.

  5. Thermal stability of LiNaR2F8 compounds (R=Ho-Lu, Y)

    International Nuclear Information System (INIS)

    Fedorov, P.P.; Medvedeva, L.V.; Bondareva, O.S.; Sobolev, B.P.

    1990-01-01

    Monoclinic pseudorhombic compound mentioned in the title are investigated. It is determined, that the compounds are stable within temperature narrow range: Ho - 575-693 degC, Er - 566-712deg C, Tm - 560-710 deg C, Yb - less than 685 deg C, Y - 580-712 deg C. Triangulation of LiF-NaF-YF 3 system is carried out

  6. Measurement of N and C diffusion in Sm{sub 2}Fe{sub 17} by magnetic relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Mommer, N.; Hirscher, M.; Gerlach, M.; Van Lier, J.; Kronmueller, H. [Max-Planck-Institut fuer Metallforschung, Stuttgart (Germany); Kubis, M.; Mueller, K.-H. [Institut fuer Festkoerper und Werkstofforschung, Institut fuer Metallische Werkstoffe, D-01171 Dresden (Germany)

    1998-10-02

    Magnetic after-effect (MAE) measurements of nitrided and carburized Sm{sub 2}Fe{sub 17} compounds were performed in the temperature range of 140 K to 480 K. Both nitrided and carburized compounds show relaxation maxima at 285 and 300 K, respectively, which are absent in pure Sm{sub 2}Fe{sub 17} compounds. Therefore, these relaxation maxima are attributed to jumps of interstitially dissolved nitrogen or carbon atoms. Numerical evaluation yielded an activation enthalpy Q{sup N} (0.84{+-}0.05) eV and a pre-exponential factor {tau}{sub 0}{sup N}=3.10{sup -15{+-}1} s for the short-range diffusion of N atoms. The corresponding values for the carbon diffusion are Q{sup C}=(0.91{+-}0.05) eV and {tau}{sub 0}{sup C}=1.10{sup -15{+-}1} s. The carbon and nitrogen content of the samples was determined from the increase in mass during nitrogenation or carburization to Sm{sub 2}Fe{sub 17}N{sub 1.2} and Sm{sub 2}Fe{sub 17}C{sub 2.6}. (orig.) 18 refs.

  7. NMR investigation of the effect of hydrostate pressure on the local magnetic fields in Y6Fe23

    International Nuclear Information System (INIS)

    Vasil'kovskij, V.A.; Bartashevich, M.I.; Gorlenko, A.A.; Kovtun, N.M.; Kupriyanov, A.K.

    1990-01-01

    The local magnetic fields at the Y 89 and Fe 57 nuclei in the intermetallic compound Y 6 Fe 23 and their shift induced by pressure are investigated by the NMR technique. The results are discussed on the basis of a model in which the atomic magnetic moment for iron includes the moment of polarized collectivized electrons responsible for the chemical bond between yttrium and iron. It is shown that with decreasing concentration of yttrium in the Y x Fe y compounds delocalization of the iron magnetic electrons occurs

  8. Integrated photooxidative-extractive desulfurization system for fuel oil using Cu, Fe and Cu-Fe/TiO2 and eutectic based ionic liquids: Effect of calcination temperature and duration

    Science.gov (United States)

    Zaid, Hayyiratul Fatimah Mohd; Kait, Chong Fai; Mutalib, Mohamed Ibrahim Abdul

    2014-10-01

    Photocatalyts TiO2 doped with Cu, Fe and Cu-Fe metal at different calcination temperature and duration were successfully prepared and characterized. Photocatalytic oxidative desulfurization of model oil containing dibenzothiophene as the sulfur compound (100 ppm) using the prepared photocatalyst was investigated. The photocatalyst calcined at 500°C and duration of 1 h showed the best performance.

  9. Effects of Fe deficiency on the riboflavin synthesis pathway in medicago truncatula plants

    Science.gov (United States)

    Riboflavin was first described to be excreted from roots of Fe-deficient tobacco plants and since then excretion and accumulation of riboflavin, as well as other flavin compounds has been reported in a wide variety of plant species. In flavinogenic yeast strains and some bacteria, Fe has been shown ...

  10. Influence of Zr substitution on the stabilization of ThMn{sub 12}-type (Nd{sub 1−α}Zr{sub α})(Fe{sub 0.75}Co{sub 0.25}){sub 11.25}Ti{sub 0.75}N{sub 1.2−1.4} (α = 0–0.3) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Sakuma, N.; Yano, M.; Kato, A. [Toyota Motor Corporation, 1200 Mishuku, Susono, Shizuoka 410-1193 (Japan); Technology Research Association of Magnetic Materials for High-Efficiency Motors (MagHEM) Higashifuji-Branch, 1200 Mishuku, Susono, Shizuoka 410-1193 (Japan); Suzuki, S.; Kuno, T.; Urushibata, K.; Kobayashi, K. [Shizuoka Institute of Science and Technology, 2200-2 Toyosawa, Fukuroi, Shizuoka 437-8555 (Japan); Manabe, A. [Technology Research Association of Magnetic Materials for High-Efficiency Motors (MagHEM) Higashifuji-Branch, 1200 Mishuku, Susono, Shizuoka 410-1193 (Japan)

    2016-05-15

    The influence of Zr substitution in ThMn{sub 12} compounds was investigated using strip casting alloys. It was found that Zr substitution stabilized (Nd{sub 1−α}Zr{sub α})(Fe{sub 0.75}Co{sub 0.25}){sub 11.25}Ti{sub 0.75}N{sub 1.2−1.4} (α = 0–0.3) compounds. Specifically, a reduction in the lattice constant along the a-axis was observed. Energy-dispersive X-ray spectroscopy mapping combined with Cs-corrected scanning transmission electron microscopy indicated that Zr atoms preferentially occupied Nd 2a sites. Both the magnetic anisotropy field and saturation polarization were maximum at Zr substitution ratio α = 0.1. The (Nd{sub 1−α}Zr{sub α})(Fe{sub 0.75}Co{sub 0.25}){sub 11.25}Ti{sub 0.75}N{sub 1.2−1.4} (α = 0–0.3) compounds displayed higher saturation polarization than Nd{sub 2}Fe{sub 14}B at high temperatures.

  11. Synthesis and magnetic properties of PrFe11V1-xTix and their nitrides

    International Nuclear Information System (INIS)

    Tang, S.L.; Wang, B.W.; Zhang, C.; Jin, X.M.; Zhang, S.Y.; Du, Y.W.

    1997-01-01

    We have succeeded in synthesizing PrFe 11 V 1-x Ti x (x=0.2 1) compound and their nitrides with the ThMn 12 -type structure. The phase formation and magnetic properties have been investigated by x-ray diffraction, differential thermometric analysis, and magnetic measurement. The stable temperature range of the 1-12 phase for PrFe 11 V 1-x Ti x alloys has been determined as a function of Ti content. PrFe 11 V compounds with the ThMn 12 -type structure do not exist and PrFe 11 Ti compounds with the TnMn 12 -type structure are obtained by annealing in a narrow temperature range between 1303 and 1383 K. Furthermore, 1-12 phase with the ThMn 12 -type structure can be obtained at lower temperature and wider temperature range with decreasing Ti content x (0.2≤x≤1). PrFe 11 V 1-x Ti x N y with x=0.2 1 has a T c of about 730 785 K, B a larger than 8 T and M s in the range 144 148 emu/g. These intrinsic magnetic properties are highly favorable for permanent magnet applications. As a preliminary, an intrinsic coercivity of 5.4 kOe is obtained for PrFe 11 V 0.5 Ti 0.5 N y at room temperature by using mechanical alloying technique. copyright 1997 American Institute of Physics

  12. Synthesis of [Fe(Leq(Lax]n coordination polymer nanoparticles using blockcopolymer micelles

    Directory of Open Access Journals (Sweden)

    Christoph Göbel

    2017-06-01

    Full Text Available Spin-crossover compounds are a class of materials that can change their spin state from high spin (HS to low spin (LS by external stimuli such as light, pressure or temperature. Applications demand compounds with defined properties concerning the size and switchability that are maintained when the compound is integrated into composite materials. Here, we report the synthesis of [Fe(Leq(Lax]n coordination polymer (CP nanoparticles using self-assembled polystyrene-block-poly(4-vinylpyridine (PS-b-P4VP block copolymer (BCP micelles as template. Variation of the solvent (THF and toluene and the rigidity of the axial ligand Lax (Lax = 1,2-di(pyridin-4-ylethane (bpea, trans-1,2-di(pyridin-4-ylethene (bpee, and 1,2-di(pyridin-4-ylethyne (bpey; Leq = 1,2-phenylenebis(iminomethylidyne-bis(2,4-pentanedionato(2− allowed the determination of the preconditions for the selective formation of nanoparticles. A low solubility of the CP in the used solvent and a high stability of the Fe–L bond with regard to ligand exchange are necessary for the formation of composite nanoparticles where the BCP micelle is filled with the CP, as in the case of the [FeLeq(bpey]n@BCP. Otherwise, in the case of more flexible ligands or ligands that lead to high spin complexes, the formation of microcrystals next to the CP–BCP nanoparticles is observed above a certain concentration of [Fe(Leq(Lax]n. The core of the nanoparticles is about 45 nm in diameter due to the templating effect of the BCP micelle, independent of the used iron complex and [Fe(Leq(Lax]n concentration. The spin-crossover properties of the composite material are similar to those of the bulk for FeLeq(bpea]n@BCP while pronounced differences are observed in the case of [FeLeq(bpey]n@BCP nanoparticles.

  13. Electric field gradient and electronic structure of linear-bonded halide compounds

    International Nuclear Information System (INIS)

    Ellis, D.E.; Guenzburger, D.J.R.; Jansen, H.B.

    1983-01-01

    The importance of covalent metal-ligand interactions in determining hyperfine fields and energy-level structure of MX 2 linear-bonded halide compounds has been studied, using the self-consistent local density molecular orbital approach. Results for FeCl 2 , FeBr 2 and EuCl 2 obtained using the Discrete Variational Method with numerical basis sets are presented. The high spin configuration for the iron compounds, first predicted by Berkowitz, et al., is verified; a successful comparison with gas phase photoelectron spectra is made. Variation of the predicted electric field gradient with bond length R is found to be rapid; the need for an EXAFS measurement of R for the matrix isolated species and experimental determination of the spin of the EFG is seen to be crucial for more accurate determinations of the sub(57) Fe quadrupole moment. (Author) [pt

  14. Magnetic Excitations in Cu2Fe2Ge4O13

    International Nuclear Information System (INIS)

    Masuda, Takatsugu; Zheludev, Andrey I.; Sales, Brian C.; Imai, S.; Uchinokura, K.

    2005-01-01

    Magnetic excitations in the cooperative ordered state in a weakly coupled Fe chains and Cu dimers compound Cu 2 Fe 2 Ge 4 O 13 is studied by thermal neutron scattering technique. We show that the low energy excitations up to 10 meV in wide q range are well described by spin wave theory of weakly coupled Fe chains. In higher energy range a narrow band excitation that can be associated with Cu dimers is observed at ℎω-24 meV. Both types of excitations can be understood by treating the weak coupling between Fe chains and Cu dimers at the level of Mean Field/Random Phase Approximation.

  15. The temperature dependence of the Moessbauer parameters and the magnetic properties of the RFe2 (R = Y or rare earth) compounds

    International Nuclear Information System (INIS)

    Barb, D.; Burzo, E.; Morariu, M.

    1975-01-01

    Temperature dependence of hyperfine fields and quadrupole splitting is presented for the following compounds: DyFe 2 , HoFe 2 , ErFe 2 , TmFe 2 , and YFe 2 . Moessbauer studies were made by an ERLON-type equipment. A 57 Co in Cu source was employed. Data were stored for a velocity range of +- 10 mm/sec using a DIDAC-4000 analyzer. The spectra were fitted by a IBM-370 type computer using a FORTRAN programme. The measurements were carried out in a temperature range from 77 K to the Curie temperature. Quadrupole splitting for all compounds varied continuously with temperature up to the Curie temperature where a sudden change was observed. The magnetic behaviour of the YFe 2 and DyFe 2 compounds was analyzed. Moessbauer results were discussed in connection with the magnetic data. (Z.S.)

  16. Exploring high-pressure FeB{sub 2}: Structural and electronic properties predictions

    Energy Technology Data Exchange (ETDEWEB)

    Harran, Ismail [School of Physical Science and Technology, Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, Southwest Jiaotong University, Chengdu, 610031 (China); Al Fashir University (Sudan); Wang, Hongyan [School of Physical Science and Technology, Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, Southwest Jiaotong University, Chengdu, 610031 (China); Chen, Yuanzheng, E-mail: cyz@calypso.org.cn [School of Physical Science and Technology, Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, Southwest Jiaotong University, Chengdu, 610031 (China); Jia, Mingzhen [School of Physical Science and Technology, Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, Southwest Jiaotong University, Chengdu, 610031 (China); Wu, Nannan [School of Mathematics, Physics and Biological Engineering, Inner Mongolia University of Science & Technology, Baotou, 014010 (China)

    2016-09-05

    The high pressure (HP) structural phase of FeB{sub 2} compound is investigated by using first-principles crystal structure prediction based on the CALYPSO technique. A thermodynamically stable phase of FeB{sub 2} with space group Imma is predicted at pressure above 225 GPa, which is characterized by a layered orthorhombic structure containing puckered graphite-like boron layers. Its electronic and mechanical properties are identified and analyzed. The feature of band structures favors the occurrence of superconductivity, whereas, the calculated Pugh's ratio reveals that the HP Imma structure exhibits ductile mechanical property. - Highlights: • The high pressure structural phase of FeB{sub 2} compound is firstly investigated by the CALYPSO technique. • A thermodynamically stable Imma phase of FeB{sub 2} is predicted at pressure above 225 GPa. • The Imma structure is characterized by a 2D boron network containing puckered graphite-like boron layers. • The band feature of Imma structure favors the occurrence of superconductivity. • The calculated Pugh's ratio suggests that the Imma structure exhibits ductile mechanical property.

  17. Corrosion evaluation of materials in sulfur compound environments

    International Nuclear Information System (INIS)

    Maoying Teng; Iuanjou Yang

    1993-01-01

    The para-toluene sulfonic acid (PTSA) serves as a catalyst in producing diethylene glycol dibenzoate (DEGDB) and decomposes with increasing time at elevated temperature. Due to the presence of bisulfite ion, it is important to evaluate the corrosion properties of materials in this metastable environments. A potentiodynamic method was used to screen materials' properties in a PTSA solution. A surface analysis technique was also performed to investigate the oxide films. The critical current density and passive current density were substantially reduced when Fe alloyed with Cr and/or Ni. With the addition of Mo in Fe-Ni-Cr alloys, the critical current density was lowered further to show the beneficial effect of alloyed Mo. A plot of the corrosion rate of materials in DEGDB as a function of Ni/Cr ratio shows the linearity with increasing Ni/Cr ratio, disregard the type of materials. The corrosion rate of pure chromium can be estimated as ∼ 2.0 mpy by extrapolation of the linearity to Ni/Cr = 0. This is also the minimum corrosion rate that even Fe-Ni-Cr alloys were alloyed with Mo. Surface analysis results showed that the dissolution of Fe and/or Ni leads to a higher surface chromium content and results in the formation of chromium oxide on metal surface. This chromium oxide then prevents metal from corrosion. It is concluded that the higher the nickel content the higher the corrosion rate of materials. The composition potential-pH diagrams for Fe-S-H 2 O and Ni-S-H 2 O show that the stability fields of FeS and NiS cover a wide range of pH. The effect of sulfur or sulfide ions in promoting dissolution of Fe and/or Ni are highly possible. The activating influence of sulfur compounds on Ni is stronger than that of Fe, although the highly electronic conductivity of iron sulfides can catalyze the cathodic reaction. Undoubtedly, sulfur compound strongly depassivates high Ni contents materials

  18. Spin-glass behavior in single crystals of hetero-metallic magnetic warwickites MgFeBO{sub 4,} Mg{sub 0.5}Co{sub 0.5}FeBO{sub 4,} and CoFeBO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Arauzo, A., E-mail: aarauzo@unizar.es [Servicio de Medidas Físicas, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza (Spain); Kazak, N.V. [L.V. Kirensky Institute of Physics, SB of RAS, 660036 Krasnoyarsk (Russian Federation); Ivanova, N.B. [Siberian Federal University, 660074 Krasnoyarsk (Russian Federation); Platunov, M.S. [L.V. Kirensky Institute of Physics, SB of RAS, 660036 Krasnoyarsk (Russian Federation); Knyazev, Yu.V. [Siberian Federal University, 660074 Krasnoyarsk (Russian Federation); Bayukov, O.A.; Bezmaternykh, L.N. [L.V. Kirensky Institute of Physics, SB of RAS, 660036 Krasnoyarsk (Russian Federation); Lyubutin, I.S.; Frolov, K.V. [Shubnikov Institute of Crystallography, RAS, 119333 Moscow (Russian Federation); Ovchinnikov, S.G. [L.V. Kirensky Institute of Physics, SB of RAS, 660036 Krasnoyarsk (Russian Federation); Siberian Federal University, 660074 Krasnoyarsk (Russian Federation); Siberian State Aerospace University, 660014 Krasnoyarsk (Russian Federation); Bartolomé, J. [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza and Departamento de Física de la Materia Condensada, 50009 Zaragoza (Spain)

    2015-10-15

    Magnetic properties of heterometallic warwickites MgFeBO{sub 4,} Mg{sub 0.5}Co{sub 0.5}FeBO{sub 4,} and CoFeBO{sub 4} are presented, highlighting the effect of Co substitution on the magnetic properties of these compounds. The analysis of magnetization and heat capacity data has shown that these compounds exhibit a spin-glass transition below T{sub SG}=10, 20 and 22 K, respectively. Using zero field ac susceptibility as entanglement witness we find that the low dimensional magnetic behavior above T{sub SG} show quantum entanglement behavior χ(Τ)∝T{sup −α(Τ)} up to T{sub E}≈130 K. The α parameters have been deduced as a function of temperature and Co content, indicating the existence of random singlet phase in this temperature region. Above T{sub E} the paramagnetism is interpreted in terms of non-entangled spins giving rise to Curie–Weiss paramagnetism. The different intra- and inter-ribbon exchange interaction pathways have been calculated within a simple indirect coupling model. It is determined that the triangular motifs in the warwickite structure, together with the competing interactions, induce frustration. The spin-glass character is explained in terms of the substitutional disorder of the Mg, Fe and Co atoms at the two available crystallographic sites, and the frustration induced by the competing interactions. The Co substitution induces uniaxial anisotropy, increases the absolute magnetization and increases the spin-glass freezing temperature. The entanglement behavior is supported in the intermediate phase irrespective of the introduction of anisotropy by the Co substitution. - Highlights: • Spin-glass transition of MgFeBO{sub 4,} Mg{sub 0.5}Co{sub 0.5}FeBO{sub 4,} and CoFeBO{sub 4}. • Anisotropy and transition temperature T{sub SG} increases with Co substitution. • Dynamical scaling theory near T{sub SG} is fulfilled. • Quantum entanglement is observed in between T{sub SG} and T{sub E}=130 K. • Low dimensional random singlet phase

  19. Electronic Properties of LiFePO4 and Li doped LiFePO4

    International Nuclear Information System (INIS)

    Zhuang, G.V.; Allen, J.L.; Ross, P.N.; Guo, J.-H.; Jow, T.R.

    2005-01-01

    The potential use of different iron phosphates as cathode materials in lithium-ion batteries has recently been investigated.1 One of the promising candidates is LiFePO4. This compound has several advantages in comparison to the state-of-the-art cathode material in commercial rechargeable lithium batteries. Firstly, it has a high theoretical capacity (170 mAh/g). Secondly, it occurs as mineral triphylite in nature and is inexpensive, thermally stable, non-toxic and non-hygroscopic. However, its low electronic conductivity (∼10-9 S/cm) results in low power capability. There has been intense worldwide research activity to find methods to increase the electronic conductivity of LiFePO4, including supervalent ion doping,2 introducing non-carbonaceous network conduction3 and carbon coating, and the optimization of the carbon coating on LiFePO4 particle surfaces.4 Recently, the Li doped LiFePO4 (Li1+xFe1-xPO4) synthesized at ARL has yield electronic conductivity increase up to 106.5 We studied electronic structure of LiFePO4 and Li doped LiFePO4 by synchrotron based soft X-ray emission (XES) and X-ray absorption (XAS) spectroscopies. XAS probes the unoccupied partial density of states, while XES the occupied partial density of states. By combining XAS and XES measurements, we obtained information on band gap and orbital character of both LiFePO4 and Li doped LiFePO4. The occupied and unoccupied oxygen partial density of states (DOS) of LiFePO4 and 5 percent Li doped LiFePO4 are presented in Fig. 1. Our experimental results clearly indicate that LiFePO4 has wideband gap (∼ 4 eV). This value is much larger than what is predicted by DFT calculation. For 5 percent Li doped LiFePO4, a new doping state was created closer to the Fermi level, imparting p-type conductivity, consistent with thermopower measurement. Such observation substantiates the suggestion that high electronic conductivity in Li1.05Fe0.95 PO4 is due to available number of charge carriers in the material

  20. Influence of a niobium coating on sulfidation resistance of FeCr and FeCrY alloys

    International Nuclear Information System (INIS)

    Geribola, Gulherme Altomari

    2014-01-01

    Niobium and niobium based alloys are currently used in many industrial applications because they offer excellent resistance to degradation in various corrosive environments. These media include gaseous atmospheres at high temperatures such as those found in existing coal gasifying plants in power plants for energy generation. These atmospheres are complex gas mixtures that contain sulfur and oxygen, among other compounds. Sulphides are thermodynamically less stable, have lower melting points and often have larger deviations from stoichiometry compared to the corresponding oxides. Although there are studies regarding the use of refractory metals in high temperature sulphidizing atmospheres, the use of niobium compounds has not been adequately evaluated and there is very little studies available in the literature about its use as a protective coating. The aim of this study was to evaluate the effect of a niobium film, deposited by magnetron sputtering on the isothermal sulphidation behavior of Fe-20Cr and Fe-20Cr-1Y alloys. The sulphidation tests were carried out at 500, 600 and 700 deg C for 2h in H 2 /2% H2S atmosphere. The sulphidation resistance was determined by mass gain per unit area. The sulphidation behavior of the coated and uncoated alloys was similar at 500 deg C, and none of the alloys scaled. At 700 deg C FeCr alloy scaled in the form of a fine powder, while the reaction product formed on the alloy FeCrY scaled in the form of plates. The effect of niobium became pronounced at 700 deg C. The reaction product layer formed on the coated alloy was thinner and more plastic than that formed on the uncoated alloy. The mass gain per unit area of the coated alloys decreased significantly and they did not scaled. (author)

  1. Atomic site occupancies and magnetic properties of Ni-doped FeAl intermetallic compounds

    CERN Document Server

    Ko, K Y; Yoon, S

    1999-01-01

    Neutron and X-ray powder diffraction revealed FeAl sub 1 sub - sub x Ni sub x alloys to have the B2(CsCl) structure with a virtually constant lattice parameter of 2.91 A and with the Ni atoms preferring the Fe sites. The annealed specimens showed paramagnetism for x 0.25 whereas the rapidly solidified specimens showed superparamagnetism for x = 0.25. The magnetization increased as the Ni concentration (x) increased. The rapidly solidified specimens, in general, showed stronger magnetic properties than the annealed ones. The magnetic properties were explained in terms of the local environmental model for magnetic atoms.

  2. The effects of boron on Tb0.27Dy0.73Fe2 compound

    International Nuclear Information System (INIS)

    Wu Lei; Chen Xicheng; Chen Xishen

    1995-01-01

    The magnetostrictive properties and microstructure of Tb 0.27 Dy 0.73 Fe 2 B x (x=0, 0.05, 0.1, 0.15, 0.2) have been investigated. Measurement of magnetic properties, X-ray diffraction and magnetostriction were made on Tb 0.27 Dy 0.73 Fe 2 B x polycrystalline samples prepared by arc melting. With the increase of boron content x, the iron-rich phase which leads to the detriment of magnetostrictive properties, decreases. The matrix phase of these alloys also has the MgCu 2 structure. The lattice constant and Curie transition temperature change only slightly. The doping of boron in the Tb 0.27 Dy 0.73 Fe 2 alloy can restrain the emergence of the iron-rich phase. The peritectic region probably shifts slightly with the addition of boron. ((orig.))

  3. 7 CFR 1927.55 - Title clearance services.

    Science.gov (United States)

    2010-01-01

    ... REGULATIONS TITLE CLEARANCE AND LOAN CLOSING Real Estate Title Clearance and Loan Closing § 1927.55 Title clearance services. (a) Responsibilities of closing agents. Services to be provided to the agency and the borrower by a closing agent in connection with the transaction vary depending on whether a title insurance...

  4. Application of [sup 57]Fe emission Moessbauer spectroscopy to the investigation of the physico-chemical consequences of the double radioactive decay [sup 57]Ni[yields][sup 57]Co[yields][sup 57]Fe in the solid state

    Energy Technology Data Exchange (ETDEWEB)

    Devillers, M.; Ladriere, J. (Univ. Catholique de Louvain, Louvain-la-Neuve (Belgium). Lab. de Chimie Inorganique et Nucleaire)

    1994-04-01

    [sup 57]Fe emission Mossbauer spectroscopy is shown to be a useful technique for investigating the cumulative recoil and Auger after-effects associated with the double electron capture decay, [sup 57]Ni[yields][sup 57]Co''->[sup 57]Fe, in the solid state. Experimental results collected in several types of nickel-containing matrices are surveyed: conducting materials (Ni metal), ionic compounds with monoatomic ligands [potassium trifluoronickelate (II)] and coordination compounds with polyatomic ligands (carboxylates). (Author).

  5. Characterization of a Fe inclusion in beryllium-matrix using auger electron spectroscopy

    International Nuclear Information System (INIS)

    Arkusk, R.; Moreno, D.; Simca, F.; Yeheskel, O.; Utzmoni, U.

    1991-04-01

    The auger electron spectroscopy techniques was employed to investigate the nature of an inclusion that had been revealed by radiography in a beryllium body produced by the hot isostatic press technique. The investigation's are that the inclusion is composed of several different iron-beryllium intermetallic compounds (BeFe 3 , BeFe 5 , Be 7 Fe). The conclusion drawn is that iron metal impurity was imbedded in the Be powder and that interdiffusion under the process's conditions gave rise to the enlarged inclusion. (author)

  6. Investigation of the electronic and magnetic structure of thin layer FeTe on Bi{sub 2}Te{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Cornils, Lasse; Manna, Sujit; Kamlapure, Anand; Haenke, Torben; Wiebe, Jens; Wiesendanger, Roland [Department of Physics, University of Hamburg, Hamburg (Germany); Hu, Jin; Mao, Zhiqiang [Department of Physics, Tulane University, New Orleans (United States); Brummerstedt Iversen, Bo; Hofmann, Philip [Interdisciplinary Nanoscience Center iNANO, Aarhus University (Denmark)

    2016-07-01

    The surprising discovery of Fe based superconductors in 2008 lead to a big effort in finding new materials with very high critical temperatures. One good example are Fe-chalcogenides. Although the parent compound FeTe is not superconducting, the situation changes drastically on interfacing the material with other substrates. Recently He and coworkers found zero resistance at the interface of Bi{sub 2}Te{sub 3} films grown on bulk FeTe, which showed a transition temperature of 12 K. In this talk we present our latest results on our investigation of the electronic and magnetic nature of epitaxially grown FeTe thin films on the topological insulator Bi{sub 2}Te{sub 3} using spin-polarized scanning tunneling microscopy and spectroscopy. Up to several monolayers of FeTe, an antiferromagnetic structure similar to the one observed on its bulk compound FeTe was clearly visible. Surprisingly we found a gap around the Fermi level indicating proximity to superconductivity in coexistence with magnetism on the nanoscale.

  7. Enthalpies of formation of selected Co{sub 2}YZ Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Ming, E-mail: myin1@hawk.iit.edu; Chen, Song; Nash, Philip

    2013-11-15

    Highlights: •Enthalpies of formation of selected Co{sub 2}YZ were measured by drop calorimeters. •Enthalpy decreases as the Z element approaches the top right corner of the periodic table. •For the Y element, enthalpy increases on increasing the number of d electrons. •Result of L2{sub 1} structured compounds agrees with first principles data. •Lattice parameters and related phase relationships were consistent with literature data. -- Abstract: Standard enthalpies of formation at 298 K of selected ternary Co{sub 2}-based Heusler compounds Co{sub 2}YZ (Y = Fe, Hf, Mn, Ti, V, Zr; Z = Al, Ga, In, Si, Ge, Sn) were measured by high temperature direct synthesis calorimetry. The measured enthalpies of formation (in kJ/mole of atoms) of the L2{sub 1} compounds are: Co{sub 2}FeGa (−25.8 ± 2.6); Co{sub 2}FeSi (−38.4 ± 2.2); Co{sub 2}FeGe (−11.6 ± 2.1); Co{sub 2}MnGa (−30.1 ± 2.3); Co{sub 2}MnSi (−42.4 ± 1.2); Co{sub 2}MnGe (−31.6 ± 3.0); Co{sub 2}MnSn (−15.6 ± 2.8); Co{sub 2}TiAl (−55.0 ± 3.7); Co{sub 2}TiGa (−54.2 ± 2.6); Co{sub 2}TiSi (−61.4 ± 1.7); Co{sub 2}TiGe (−59.3 ± 3.8); Co{sub 2}TiSn (−38.4 ± 2.0); Co{sub 2}VGa (−28.4 ± 1.1) and for the B2 compounds: Co{sub 2}FeAl (−22.5 ± 2.5), Co{sub 2}MnAl (−27.6 ± 2.7). Values are compared with those from first principles calculation when available and the extended semi-empirical model of Miedema. Trends in enthalpy of formation with element atomic number are discussed. Lattice parameters of the compounds with L2{sub 1} structure are determined by X-ray diffraction analysis.

  8. Structure and Phase Transformation in the Giant Magnetostriction Laves-Phase SmFe2

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaonan; Lin, Kun; Gao, Qilong; Zhu, He; Li, Qiang; Cao, Yili; Liu, Zhanning; You, Li; Chen, Jun; Ren, Yang [Argonne National Laboratory, X-Ray Science Division, Argonne, Illinois 60439, United States; Huang, Rongjin [Key Laboratory; Lapidus, Saul H. [Argonne National Laboratory, X-Ray Science Division, Argonne, Illinois 60439, United States; Xing, Xianran

    2017-10-13

    As one class of the most important intermetallic compounds, the binary Laves-phase is well-known for their abundant magnetic properties. Samarium-iron alloy system, SmFe2, is a prototypical Laves compound that shows strong negative magnetostriction but relatively weak magnetocrystalline anisotropy. SmFe2 has been identified as a cubic Fd$ \\overline{3}\\ $m structure at room temperature, however, the cubic symmetry does not match the spontaneous magnetization along the [111]cubic direction. Here we studied the crystal structure of SmFe2 by high-resolution synchrotron X-ray powder diffraction and X-ray total scattering methods. SmFe2 is found to adopt a centrosymmetric trigonal R$ \\overline{3}\\ $m structure at room temperature, which transforms to an orthorhombic Imma structure at 200 K. This transition is in agreement with the changes of easy magnetization direction from [111]cubic to [110]cubic direction, and is further evidenced by the inflexion of thermal expansion behavior, the sharp decline of the magnetic susceptibility in the FC-ZFC curve, and the anomaly in the specific heat capacity measurement. The revised structure and phase transformation of SmFe2 could be useful to understand the magnetostriction and related physical properties of other RM2-type pseudo-cubic Laves-phase intermetallic compounds.

  9. The effect of hydrogen absorption on the structural, electronic and magnetic properties of the C15 Friauf-Laves phase compounds CeFe2, CeRu2 and LaRu2 : an x-ray absorption spectroscopy (XAS) study

    International Nuclear Information System (INIS)

    Chaboy, J.; Garcia, J.; Marcelli, A.

    1995-08-01

    An x-ray absorption spectroscopy (XAS) investigation of the structural changes occurred upon hydriding in the Friauf-Laves phase compounds CeFe 2 , CeRu 2 and LaRu 2 compounds is presented. The analysis of the extended x-ray absorption spectroscopy (EXAFS) spectra at the L-edges of the rare-earth and at the Fe K-edge indicates that the hydrogenation process leads to the suppression of the long-range crystalline order in all the hydride derivates investigated, as well as the different influence of H 2 in both the rare earth and transition metal sublattices. The correlation between the structural and magnetic changes induced by the hydrogen in the lost matrix is discussed in terms of the modification of the electronic properties, i.e., intermediate-valence of Ce, and of the hybridization between the transition metal and rare-earth

  10. National Ignition Facility Title II Design Plan

    International Nuclear Information System (INIS)

    Kumpan, S

    1997-01-01

    This National Ignition Facility (NIF) Title II Design Plan defines the work to be performed by the NIF Project Team between November 1996, when the U.S. Department of Energy (DOE) reviewed Title I design and authorized the initiation of Title H design and specific long-lead procurements, and September 1998, when Title 11 design will be completed

  11. Thermodynamic modeling of the Co-Fe-O system

    DEFF Research Database (Denmark)

    Zhang, Weiwei; Chen, Ming

    2013-01-01

    As a part of the research project aimed at developing a thermodynamic database of the La-Sr-Co-Fe-O system for applications in Solid Oxide Fuel Cells (SOFCs), the Co-Fe-O subsystem was thermodynamically re-modeled in the present work using the CALPHAD methodology. The solid phases were described...... using the Compound Energy Formalism (CEF) and the ionized liquid was modeled with the ionic two-sublattice model based on CEF. A set of self-consistent thermodynamic parameters was obtained eventually. Calculated phase diagrams and thermodynamic properties are presented and compared with experimental...

  12. Phase transformations in interstitial Fe-N alloys

    Energy Technology Data Exchange (ETDEWEB)

    Liapina, T.

    2005-04-15

    Nitriding is a prominent thermochemical heat-treatment procedure leading to various types of surface property improvements of the treated iron and steel. Many questions regarding even very basic properties of these compound layers and the relevant nitride phases are still open. Some of these open questions related with the behaviour of iron nitrides and, in particular, of iron nitride compound layers occurring below the usual process temperatures are addressed to in this thesis, as relevant e.g. for the cooling procedure after nitriding. The most important iron nitrides occurring in iron-nitride compound layers are the {gamma}'- and {epsilon}-phases in the Fe-N system. It is shown that for relatively low nitrogen contents of epsilon-iron nitrides (around Fe{sub 3}N) the cooling rate upon going down from an elevated annealing temperature to room temperature has a significant effect on the lattice parameters. X-ray and neutron diffraction analysis revealed that the lattice parameter values observed after fast cooling are affected by the higher degree of nitrogen disorder at elevated temperature, thus changing the c/a ratio. New relations between the lattice parameters of {epsilon}-iron nitrides and the nitrogen content are suggested for different types of cooling. The investigation by TEM of the decomposition upon annealing (633 K, 673 K) of initially homogeneous {epsilon}-Fe{sub 3}N powders revealed that the {gamma}'-formation occurs in only a few powder particles in a grain-like form. Moreover, diffraction line-profile analysis revealed N transport occurring from particle to particle, leading to inhomogeneities of N content in the epsilon-phase. It was shown that {gamma}'-iron nitride formation can occur by backwards growth of the existing {gamma}'-sublayer at the cost of the {epsilon}-sublayer increasing N concentration in the {epsilon}-layer. Another process, which may additionally occur in the compound layer upon annealing, is diffusion of N

  13. Microstructure, AC impedance and DC electrical conductivity characteristics of NiFe2-xGdxO4 (x = 0, 0.05 and 0.075

    Directory of Open Access Journals (Sweden)

    K. Kamala Bharathi

    2012-03-01

    Full Text Available The structure and electrical characteristics of Gd doped Ni ferrite materials, namely NiFe1.95Gd0.05O4 and NiFe1.925Gd0.075O4, are reported to demonstrate their improved electrical properties compared to that of pure NiFe2O4. NiFe1.95Gd0.05O4 and NiFe1.925Gd0.075O4 compounds crystallize in the cubic inverse spinel phase with a very small amount of GdFeO3 additional phase while pure NiFe2O4 crystallize in inverse spinel phase without any impurity phase. The back scattered electron imaging analysis indicate the primary and secondary formation in NiFe1.95Gd0.05O4 and NiFe1.925Gd0.075O4 compounds. Atomic force microscopy measurements indicate that the bulk grains are ∼2-5 micron size while the grain boundaries are thin compared to bulk grains. Impedance spectroscopic analysis at different temperature indicates the different relaxation mechanisms and their variation with temperature, bulk grain and grain-boundary contributions to the electrical conductivity (Rg and capacitance (Cg of these materials. The conductivity in pure NiFeO4 is found to be predominantly due to intrinsic bulk contribution (Rg=213 kΩ and Cg=4.5 x 10-8 F. In the case of NiFe1.95Gd0.05O4 and NiFe1.925Gd0.075O4 compounds, grain and grain-boundary contributions to the conductivity are clearly observed. The DC conductivity values (at 300 K of NiFe2O4, NiFe1.95Gd0.05O4 and NiFe1.925Gd0.075O4 compounds are found to be 1.06 x 10-7 Ω-1 cm-1, 5.73 x 10-8 Ω-1 cm-1 and 1.28 x 10-8 Ω-1 cm-1 respectively.

  14. 24 CFR 202.12 - Title II.

    Science.gov (United States)

    2010-04-01

    ... INSTITUTIONS AND MORTGAGEES Title I and Title II Specific Requirements § 202.12 Title II. (a) Tiered pricing—(1... rate up to two percentage points under the mortgagee's customary lending practices must be based on... after accounting for the value of servicing rights generated by making the loan and other income to the...

  15. Formation of nitrogen-containing compounds during microwave pyrolysis of microalgae: Product distribution and reaction pathways.

    Science.gov (United States)

    Huang, Feng; Tahmasebi, Arash; Maliutina, Kristina; Yu, Jianglong

    2017-12-01

    The formation of nitrogen-containing compounds in bio-oil during microwave pyrolysis of Chlorella and Spirulina microalgae has been investigated in this study. Activated carbon (AC) and magnetite (Fe 3 O 4 ) were used as microwave receptors during microwave pyrolysis experiments. It has been found that the use of Fe 3 O 4 increased the total yield of bio-oil. The use of different microwave receptors did not seem to have affected the total yield of nitrogen-containing compounds in the bio-oil. However, Fe 3 O 4 promoted the formation of nitrogen-containing aliphatics, thereby reducing the formation of nitrogen-containing aromatics. The use of AC promoted the dehydration reactions during amino acid decomposition, thereby enhancing the formation of nitrogen-containing aromatics during pyrolysis. From the gas chromatography-mass spectrometry (GC-MS) analysis results, the major high-value nitrogen-containing compounds in the pyrolysis bio-oil of Chlorella and Spirulina were identified as indole and dodecamide. The formation mechanisms of nitrogen-containing compounds were proposed and discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Synthesis and structural characteristics of the spinel-type solid solutions in the Mn-V-Fe-O system

    International Nuclear Information System (INIS)

    Ponomaryov, V.I.; Dubrovina, I.N.; Zakharov, R.G.

    1976-01-01

    The part of the spinel region bounded by the compounds Mn 3 O 4 , Mn 2 VO 4 , Fe 2 VO 4 , and Fe 3 O 4 in the four-component system Mn-V-Fe-O was studied. The compounds were synthesized by ceramic technology. Samples were heated in a CO 2 atmosphere free of oxygen at 1100 0 C for 25-50 hr. It was found that the average composition of the spinel compound in the system had the formula Mnsub(1.00)Fesub(1.33)Vsub(0.67)O 4 . X-ray and neutron radiogrphic analyses were made. Crystallo-chemical formulas of the solid solutions considered are tabulated. The magnetic moments of saturation, calculated by the Neel model, are shown, and their experimental values are presented. The crystallo-chemical formulas of the spinel solid solutions in the Mn-V-Fe-O system are of interest in interpreting the concentration dependence of the physico-chemical properties of solid solutions of oxides based on metals with varying valence

  17. INIS: Authority list for journal titles

    International Nuclear Information System (INIS)

    2007-01-01

    This is the 33rd revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). This list is published annually and includes the titles of all journals which have contained articles submitted to INIS at the time of publication. The current list contains 13 396 journal titles, 2 170 regularly scanned journals and 578 key journals. It was last updated in February 2007. A journal - or periodical - is a continuing publication issued in a succession of discrete parts, usually bearing numbering and/or chronological designations and intended to be continued indefinitely. It is generally published within a defined, fixed interval between issues and normally appears more than once per year. It includes a mixture of articles, letters, summaries, etc. Within this definition, annuals such as the Annual Review of Nuclear Science are included, but series titles such as the McGraw-Hill Series in Nuclear Engineering are not. The purpose of this document is to provide descriptive cataloguers with standard elements to include in bibliographic level 'S' of the INIS record. These elements include field (tag) 229 (Full Journal Title), 320 (ISSN) and 321 (CODEN). The full journal title is mandatory, and either the ISSN or the CODEN must be included (both may appear). Instructions on how to use this and other elements of the INIS record format are found in INIS: Guide to Bibliographic Description (IAEA-INIS-1). In order to help the user find titles easily, the list is arranged in six parts, followed by summary statistics: - In Part I, all key journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. - In Part II, all key journals are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. - In Part III, all journals that are regularly scanned by

  18. Pressure-dependent ground states and fermiology in β- ( BDA-TTP ) 2 M Cl4 ( M=Fe,Ga )

    Science.gov (United States)

    Choi, E. S.; Graf, D.; Brooks, J. S.; Yamada, J.; Akutsu, H.; Kikuchi, K.; Tokumoto, M.

    2004-07-01

    We have investigated pressure- and magnetic-field-dependent electrical transport properties in the charge transfer salts β-(BDA-TTP)2MCl4(M=Fe,Ga) , both of which show a metal-insulator (MI) transition around 120K at ambient pressure. The zero field temperature-pressure phase diagrams of the two compounds are quite similar; the MI transition temperature decreases with pressure, and superconductivity is observed in both the magnetic and non-magnetic compounds above ˜4.5kbar . Likewise, Shubnikov-de Haas effect measurements show nearly identical Fermi surfaces. These similarities suggest that the magnetic interaction J between the conduction electrons and the magnetic moments in β-(BDA-TTP)2FeCl4 is small. Nevertheless, magnetoresistance measurements show remarkable differences and reveal that magnetic interactions with the conduction electrons are still effective in M=Fe compounds.

  19. Moessbauer spectroscopy characterization of Zr-Nb-Fe phases

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, C.P. [CONICET, Av. Gral. Paz 1499, 1650 Buenos Aires (Argentina)]. E-mail: ciramos@cnea.gov.ar; Granovsky, M.S. [CAC-CNEA, Av. Gral. Paz 1499, 1650 Buenos Aires (Argentina); Saragovi, C. [CAC-CNEA, Av. Gral. Paz 1499, 1650 Buenos Aires (Argentina)

    2007-02-01

    The aim of this work was the characterization of the ternary phases and of those coming from the corresponding binary systems in the Zr-Nb-Fe diagram by means of Moessbauer spectroscopy. This is part of a complete study involving a tentative isothermal section at 900 deg. C of the center of the Zr-Nb-Fe diagram which will be published elsewhere. Zr-Nb-Fe alloys with Nb contents between 5 and 50 at% and Fe contents between 10 and 60 at% were analyzed after a heat treatment at 900 deg. C for 4 month. Moessbauer characterization of the phases was complemented by optical and scanning electron microscopies, X-ray diffraction and electron microprobe analysis. From the obtained results it can be inferred that Fe in both of the Laves phases present in this system (Zr(FeNb){sub 2} and (ZrNb)Fe{sub 2}) sees different environments, producing quadrupole splitting and hyperfine field distributions, respectively. Two types of body centered cubic {beta} phases (Zr-rich and Nb-rich) were found having noticeable differences in their Moessbauer parameters. Furthermore it was shown that the ternary Fe(NbZr){sub 2} compound would show magnetic character at low temperatures. Concentration dependence of the hyperfine parameters and their relations with the lattice parameters contributed to the structural characterization of the phases.

  20. Moessbauer spectroscopy characterization of Zr-Nb-Fe phases

    International Nuclear Information System (INIS)

    Ramos, C.P.; Granovsky, M.S.; Saragovi, C.

    2007-01-01

    The aim of this work was the characterization of the ternary phases and of those coming from the corresponding binary systems in the Zr-Nb-Fe diagram by means of Moessbauer spectroscopy. This is part of a complete study involving a tentative isothermal section at 900 deg. C of the center of the Zr-Nb-Fe diagram which will be published elsewhere. Zr-Nb-Fe alloys with Nb contents between 5 and 50 at% and Fe contents between 10 and 60 at% were analyzed after a heat treatment at 900 deg. C for 4 month. Moessbauer characterization of the phases was complemented by optical and scanning electron microscopies, X-ray diffraction and electron microprobe analysis. From the obtained results it can be inferred that Fe in both of the Laves phases present in this system (Zr(FeNb) 2 and (ZrNb)Fe 2 ) sees different environments, producing quadrupole splitting and hyperfine field distributions, respectively. Two types of body centered cubic β phases (Zr-rich and Nb-rich) were found having noticeable differences in their Moessbauer parameters. Furthermore it was shown that the ternary Fe(NbZr) 2 compound would show magnetic character at low temperatures. Concentration dependence of the hyperfine parameters and their relations with the lattice parameters contributed to the structural characterization of the phases

  1. Pre-compound neutron evaporation in heavy ion fusion reactions

    International Nuclear Information System (INIS)

    Ajay Kumar; Singh, Hardev; Rajesh Kumar; Govil, I.M.; Golda, K.S.; Rakesh Kumar; Datta, S.K.; Yogi, B.K.; Viesti, G.

    2007-01-01

    In the present investigation, exclusive neutron spectra have been measured in coincidence with the observed γ-rays characteristic to the residual nuclei 53 Fe, 55 Fe and 56 Co. In this new experimental study, we have followed the strategy of forming the compound nucleus 58 Ni at the same excitation energy through two different entrance channels viz the mass symmetric reaction 31 P + 27 Al and the mass asymmetric reaction 12 C + 46 Ti

  2. Formation of SmFe{sub 5}(0001) ordered alloy thin films on Cu(111) single-crystal underlayers

    Energy Technology Data Exchange (ETDEWEB)

    Yabuhara, Osamu; Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi, E-mail: yabuhara@futamoto.elect.chuo-u.ac.j [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan)

    2010-01-01

    SmFe{sub 5}(0001) single-crystal thin films are prepared by molecular beam epitaxy employing Cu(111) single-crystal underlayers on MgO(111) substrates. The Cu atoms diffuse into the Sm-Fe layer and substitute the Fe sites in SmFe{sub 5} structure forming an alloy compound of Sm(Fe,Cu){sub 5}. The Sm(Fe,Cu){sub 5} film is more Cu enriched with increasing the substrate temperature. The Cu underlayer plays an important role in assisting the formation of the ordered phase.

  3. Electric Field Gradients at Hf and Fe Sites in Hf2Fe Recalculated

    International Nuclear Information System (INIS)

    Belosevic-Cavor, J.; Cekic, B.; Novakovic, N.; Koteski, V.; Milosevic, Z.

    2004-01-01

    The electric field gradients (EFG) of the Hf 2 Fe intermetallic compound were calculated using the full-potential linearized augmented plain-wave (FP-LAPW) method as embodied in the WIEN 97 code. The obtained values are compared with other ab-initio calculations and on a qualitative basis with the previously reported experimental data obtained from TDPAC. The calculated results, -23.1.10 21 V/m 2 and 2.7.10 21 V/m 2 for Hf 48f and Fe 32e position, respectively, are in excellent agreement with experimental data (23.4.10 21 V/m 2 and 2.7.10 21 V/m 2 ), better than those reported in earlier calculations. The calculated EFG for Hf 16c position (4.2.10 21 V/m 2 ) is stronger than the experimental one (1.1.10 21 V/m 2 ).

  4. Synthesis and anti-lung cancer activity of a novel arsenomolybdate compound

    Science.gov (United States)

    Zhu, Tian-Tian; Wang, Juan; Chen, Song-Hu

    2017-12-01

    The new compound based on Wells-Dawson-type arsenomolybdate: [{Cu10(pz)11Cl4}{As2IIIAs2VMo6VMo12VIO62}]·H2O (1) has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis, X-ray powder diffraction (XRPD), XPS spectroscopy and thermogravimetric analysis (TG). Compound 1 is consisted of two As caps Wells-dawson-type arsenomolybdate and {Cu10(py)11} complexes by chloride bridge. In addition, the antitumor effects of the title compound 1 were studied on three human lung cancer cells (A549, SK-LU-1 and SW1573). The results showed that compared with the positive reference drug carboplatin, compound 1 displayed efficient antitumor activity.

  5. Raman scattering, magnetization and magnetotransport study of SrFeO{sub 3-{delta}}, Sr{sub 3}Fe{sub 2}O{sub 7-{delta}} and CaFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Damljanovic, Vladimir

    2008-12-16

    In this thesis we have determined the Raman spectra as well as the magnetization, resistance and magnetoresistance of the compounds SrFeO{sub 3-{delta}}, Sr{sub 3}Fe{sub 2}O{sub 7-{delta}} and CaFeO{sub 3} as a function of temperature. We describe the preparation of nearly stoichiometric SrFeO{sub 3-{delta}} crystals with {delta}<0.05. we have performed lattice dynamics calculations for the ideal composition SrFeO{sub 3.00} in order to assign the phonon modes observed in infra-red experiments. We have measured the Raman spectra of the tetragonal phase in the temperature range 13 K to 300 K and of the orthorhombic phase in the temperature range 6 K to 475 K. We have measured the temperature dependence of the magnetization for the magnetic field along high-symmetry axes of the crystal structure. We have also performed neutron diffraction measurements. The resistivity and the magnetoresistance were measured in the range 10 K to 300 K. Finally we have measured the Raman spectra of the same sample in the temperature range 15 K to 440 K. In order to assign the observed modes, we have performed lattice dynamics calculations based on the published crystal structure of Sr{sub 3}Fe{sub 2}O{sub 7}. (orig.)

  6. Influence of Fe doped on the magnetocaloric behavior of La_{{2}/{3}} Ca_{{1}/{3}} Mn1-x Fe x O3 compounds: a Monte Carlo simulation

    Science.gov (United States)

    Alzate-Cardona, J. D.; Barco-Rios, H.; Restrepo-Parra, E.

    2018-02-01

    The magnetocaloric behavior of La{2/{3}} Ca{1/{3}} Mn1-x Fe x O3 for x  =  0.00, 0.02, 0.03, 0.05, 0.07, 0.08 and 0.10 under the influence of an external magnetic field was simulated and analyzed. Simulations were carried out using the Monte Carlo method and the classical Heisenberg model under the Metropolis algorithm. These mixed valence manganites are characterized by having three types of magnetic ions corresponding to Mn4+≤ft(S=\\frac{3}{2}\\right) , which are bonded with Ca2+ , and Mneg3+ and Mneg\\prime3+ (S=2) , related to La3+ . The Fe ions were randomly included, replacing Mn ions. With this model, the magnetic entropy change, Δ S , in an isothermal process was determined. -Δ Sm showed maximum peaks around the paramagnetic-ferromagnetic transition temperature, which depends on Fe doping. Relative cooling power was computed for different Fe concentrations varying the magnetic applied field. Our model and results show that the Fe doping decreases the magnetocaloric effect in the La{2/{3}} Ca{1/{3}} Mn1-x Fe x O3, making this a bad candidate for magnetic refrigeration. The strong dependence of the magnetocaloric behavior on Fe doping and the external magnetic field in La{2/{3}} Ca{1/{3}} Mn1-x Fe x O3 can boost these materials for the future technological applications.

  7. 20 CFR 416.573 - How much will we withhold from your title II and title VIII benefits to recover a title XVI...

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false How much will we withhold from your title II... Payment of Benefits, Overpayments, and Underpayments § 416.573 How much will we withhold from your title...-due benefits. (b)(1) We will collect the overpayment from current monthly benefits due in a month by...

  8. Iodine as an oxidant in the topotactic deintercalation of interstitial iron in Fe(1+x)Te.

    Science.gov (United States)

    Rodriguez, Efrain E; Zavalij, Peter; Hsieh, Ping-Yen; Green, Mark A

    2010-07-28

    The layered telluride, Fe(1+x)Te, is a parent compound of the isostructural and superconducting phases, Fe(1+x)(Te, Se, S). Here we show that, through a simple reaction of I(2) vapor with both powder and single crystal samples, the interstitial iron can be removed from the FeTe framework topotactically. Neutron powder diffraction and X-ray single crystal diffraction confirm that the iron being extracted is the partially occupied site that lies between the 2-D blocks of edge-sharing FeTe(4) tetrahedra. The deintercalation process has consequences for both magnetic and crystallographic phase transitions in the compound at low temperatures. This technique could be of use for the tuning of stoichiometry of the superconducting phases and therefore enable more careful studies on how chemical composition affects magnetic and superconducting properties.

  9. Structural, magnetic and thermal properties of CaMn0.9957Fe0.01O3-δ

    International Nuclear Information System (INIS)

    Przewoznik, J.; Chmist, J.; Kolwicz-Chodak, L.; Tarnawski, Z.; Kapusta, Cz.; Kolodziejczyk, A.

    2007-01-01

    The polycrystalline CaMn 0.99 57 Fe 0.01 O 3-δ compound was studied using powder X-ray diffraction, 57 Fe Moessbauer spectroscopy, ac susceptometry, dc magnetometry, specific heat and electrical resistivity measurements. X-ray diffraction measurements performed between 70 and 300 K show a thermal expansion anomaly at the Neel temperature. A weak ferromagnetic component and a spin-glass behaviour below Neel temperature are found in magnetic measurements. The Moessbauer spectroscopy measurements performed between 30 and 300 K provided the Neel temperature value of 118 K, the same as obtained from dc magnetisation and close to that derived from the specific heat (119 K). The temperature evolution of the Fe hyperfine field was analysed within a molecular field model and revealed equal strengths of the Fe-Mn and Mn-Mn exchange interactions in this compound

  10. Solid-state amorphization of SmFe3 by hydrogenation

    International Nuclear Information System (INIS)

    Mueller, K.H.; Kubis, M.; Handstein, A.; Gutfleisch, O.

    2000-01-01

    Hydrogen-induced amorphization (HIA) has received much attention as a method for the preparation of amorphous compounds since its discovery by Yeh et al. Meanwhile it has been observed for a large number of intermetallic compounds with C15, C23, B8 2 , DO 19 and L1 2 structures. E.G. the C15 Laves-type compounds (MgCu 2 -type structure) of rare earth (R) - transition metal (T) compounds RT 2 show HIA for R = Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho and Er. Aoki et al. postulated that new amorphizing compounds can be expected at high hydrogen pressures. In this work, the structural changes of SmFe 3 (PuNi 3 -type structure) during heating in high hydrogen pressures are reported

  11. Standard enthalpies of formation of selected Rh2YZ Heusler compounds

    International Nuclear Information System (INIS)

    Yin, Ming; Nash, Philip

    2015-01-01

    The standard enthalpies of formation (Δ f H°) of selected ternary Rh-based Rh 2 YZ (Y = Cu, Fe, Mn, Ni, Ru, Ti, V; Z = Al, Ga, In, Si, Ge, Sn) compounds were measured using high temperature direct reaction calorimetry. The measured standard enthalpies of formation (in kJ/mol of atoms) are, for the Heusler compound Rh 2 MnSn (−40.1 ± 3.6), for the B2-structured compounds: Rh 2 FeAl (−48.5 ± 2.9); Rh 2 MnAl (−72.4 ± 2.7); Rh 2 MnGa (−55.3 ± 2.0); Rh 2 MnIn (−35.3 ± 1.9), for the tetragonal compounds: Rh 2 FeSn (−28.9 ± 1.3); Rh 2 TiAl (−97.6 ± 2.2); Rh 2 TiGa (−79.0 ± 1.8); Rh 2 TiSn (−74.7 ± 3.1). Values are compared with those from first principles calculations in published papers and the Open Quantum Materials Database (OQMD). Lattice parameters of these compounds are determined using X-ray diffraction analysis (XRD). Microstructures were characterized using scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). - Highlights: • Standard enthalpies of formation of Rh 2 YZ were measured using a drop calorimeter. • Measured enthalpies agree with first principles data in general. • Lattice parameters and related phase relationships were consistent with literature data. • Rh 2 TiSn of tI8 structure were reported for the first time.

  12. Mineral and organic compounds in leachate from landfill with concentrate recirculation.

    Science.gov (United States)

    Talalaj, Izabela Anna

    2015-02-01

    The effect of a reverse osmosis concentrate recirculation on the mineral and organic compounds in a landfill leachate was investigated. Investigated was the quality of a leachate from two landfills operated for different periods (a 20-year-old Cell A and a 1-year-old Cell B), where the concentrate was recirculated. Examined were general parameters (conductivity, pH), organic compounds (biochemical oxygen demand (BOD), chemical oxygen demand (COD), total organic nitrogen, BOD/COD), and inorganic compounds (nitrogen ammonia, sulfite, sulfate, cyanide, boron, chloride, ferrous, zinc, chrome, copper). The findings from the first year of investigation showed that over the initial period of recirculation, the concentration of organic compounds (BOD, COD) increased, but after 6 months their values stabilized. It indicates that the concentrate recirculation accelerated organic decomposition, especially in the new landfill Cell. The analysis of inorganic parameters showed that recirculation landfills produce a leachate with a higher concentration of N-NH4, and Cl(-). In case of the old landfill Cell, an increase in B and Fe was also noticeable. These compounds are cyclically washed out from a waste dump and require an additional pretreatment in order to exclude them from recirculation cycle. The increased concentration of Cu, Zn, and Fe was noticed during the initial months of recirculation and in the season of intense atmospheric precipitation in the leachate from both Cells. Higher values of electro conductivity, Cl(-), N-NH4 (+), B, and Fe in the leachate from the old field indicate that the attenuation capacity of this landfill is close to exhaustion.

  13. Nuclear orientation of 9597Nb and 95Zr in ZrFe2

    International Nuclear Information System (INIS)

    Krane, K.S.; Olsen, C.E.; Rosenblum, S.S.; Steyert, W.A.

    1976-01-01

    The angular distribution anisotropies of γ rays were measured following the decays of 95 , 97 Nb and 95 Zr oriented at low temperatures in the ferromagnetic Laves phase compound ZrFe 2 . The magnetic hyperfine field of Nb in ZrFe 2 was deduced to be 9.4+-1.6 T; that of Zr in ZrFe 2 was estimated to be 15+-4 T. The nuclear magnetic moment of 97 Nb was deduced to be μ = (7.5+-1.4) μ/subN/

  14. Arsenic-Rich Polyarsenides Stabilized by Cp*Fe Fragments.

    Science.gov (United States)

    Schmidt, Monika; Konieczny, David; Peresypkina, Eugenia V; Virovets, Alexander V; Balázs, Gabor; Bodensteiner, Michael; Riedlberger, Felix; Krauss, Hannes; Scheer, Manfred

    2017-06-12

    The redox chemistry of [Cp*Fe(η 5 -As 5 )] (1, Cp*=η 5 -C 5 Me 5 ) has been investigated by cyclic voltammetry, revealing a redox behavior similar to that of its lighter congener [Cp*Fe(η 5 -P 5 )]. However, the subsequent chemical reduction of 1 by KH led to the formation of a mixture of novel As n scaffolds with n up to 18 that are stabilized only by [Cp*Fe] fragments. These include the arsenic-poor triple-decker complex [K(dme) 2 ][{Cp*Fe(μ,η 2:2 -As 2 )} 2 ] (2) and the arsenic-rich complexes [K(dme) 3 ] 2 [(Cp*Fe) 2 (μ,η 4:4 -As 10 )] (3), [K(dme) 2 ] 2 [(Cp*Fe) 2 (μ,η 2:2:2:2 -As 14 )] (4), and [K(dme) 3 ] 2 [(Cp*Fe) 4 (μ 4 ,η 4:3:3:2:2:1:1 -As 18 )] (5). Compound 4 and the polyarsenide complex 5 are the largest anionic As n ligand complexes reported thus far. Complexes 2-5 were characterized by single-crystal X-ray diffraction, 1 H NMR spectroscopy, EPR spectroscopy (2), and mass spectrometry. Furthermore, DFT calculations showed that the intermediate [Cp*Fe(η 5 -As 5 )] - , which is presumably formed first, undergoes fast dimerization to the dianion [(Cp*Fe) 2 (μ,η 4:4 -As 10 )] 2- . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Ferrous ammonium phosphate (FeNH₄PO₄) as a new food fortificant: iron bioavailability compared to ferrous sulfate and ferric pyrophosphate from an instant milk drink.

    Science.gov (United States)

    Walczyk, Thomas; Kastenmayer, Peter; Storcksdieck Genannt Bonsmann, Stefan; Zeder, Christophe; Grathwohl, Dominik; Hurrell, Richard F

    2013-06-01

    The main purpose of this study was to establish bioavailability data in humans for the new (Fe) fortification compound ferrous ammonium phosphate (FAP), which was specially developed for fortification of difficult-to-fortify foods where soluble Fe compounds cannot be used due to their negative impact on product stability. A double-blind, randomized clinical trial with cross-over design was conducted to obtain bioavailability data for FAP in humans. In this trial, Fe absorption from FAP-fortified full-cream milk powder was compared to that from ferric pyrophosphate (FPP) and ferrous sulfate. Fe absorption was determined in 38 young women using the erythrocyte incorporation dual stable isotope technique (⁵⁷Fe, ⁵⁸Fe). Geometric mean Fe absorption from ferrous sulfate, FAP and FPP was 10.4, 7.4 and 3.3 %, respectively. Fe from FAP was significantly better absorbed from milk than Fe from FPP (p soluble reference compound (p = 0.0002). Absorption ratios of FAP and FPP relative to ferrous sulfate as a measure of relative bioavailability were 0.71 and 0.32, respectively. The results of the present studies show that replacing FPP with FAP in full-cream milk could significantly improve iron bioavailability.

  16. Synthesis and characterization of polycrystalline brownmillerite cobalt doped Ca{sub 2}Fe{sub 2}O{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Dhankhar, Suchita; Baskar, K.; Singh, Shubra, E-mail: shubra6@gmail.com [Crystal Growth Centre, Anna University, Chennai-600 025 (India); Bhalerao, Gopal [UGC-DAE CSR Kalpakkam node, Kalpakkam-603104 (India)

    2016-05-23

    Brownmillerite compounds with general formula A{sub 2}BB’O{sub 5} (BB’ = Mn, Al, Fe, Co) have attracted attention in wide range of applications such as in solid oxide fuel cell, oxygen separation membrane and photocatalysis. Brownmillerite compounds have unique structure with alternate layers of BO{sub 6} octahedral layers and BO{sub 4} tetrahedral layers. Presence of dopants like Co in place of Fe increases oxygen vacancies. In the present work we have synthesized polycrystalline Ca{sub 2}Fe{sub 2}O{sub 5} and Ca{sub 2}Fe{sub 1-x}Co{sub x}O{sub 5} (x = 0.01, 0.03) by citrate combustion route. The as prepared samples were characterized by XRD using PANalytical X’Pert System, DRS (Diffuse reflectance spectroscopy) and SEM (Scanning electron microscopy).

  17. A study on the alkali leaching of complex compound for molybdenum trioxide and ferric oxide

    International Nuclear Information System (INIS)

    Kim, C.G.; Whang, Y.K.

    1981-01-01

    This study is to determine the alkali-leaching meachanism by which complex compound by the reaction made between molybdenite (MoS 2 ) and ferric oxide (Fe 2 O 3 ) in the roasted are when molybdenum trioxide (MoO 3 ) is formed by the roasting reaction of molybdenite concentrate. The results obtained from this experiment are summarized as follows: The heating reaction analysis shows that the complex compound of iron molybdates (Fe 2 O 3 .3-4 MoO 3 ) is formed by the reaction of molybdenum trioxide and ferric oxide at temperatures of above 500 0 C. It is shown that at various reaction temperature below 400 0 C molybdenum trioxide is almost completely leached by caustic soda irrespective of the mole ratio of two chemical samples used for the experiment, whereas at temperature above 400 0 C the leaching rate of molybdenum trioxide decreases except that it varies from 70.77% at a temperature of 900 0 C at which the mole ratio is 1 to 1 to 84.08% at a temperature of 1000 0 C. The x-ray diffraction analysis has shown that the complex compound reacted at a temperature of 1000 0 C produces a complex compound with the crystal structure of iron molybdates, and the alkali-leached residues even with 19.0% of molybdenum trioxide, however, contain only α-Fe 2 O 3 , without showing iron molybdates. The crystalline compound of iron molybdates obtained as a result of heating reaction was leached by using caustic soda, while MoO 3 and Fe 2 O 3 in the leaching residue was found to contain other compounds unable to be leached by caustic soda. (author)

  18. Fine structure at the diffusion welded interface of Fe3Al/Q235 ...

    Indian Academy of Sciences (India)

    Unknown

    iron lattice sites (Fair and Wood 1994). 3.2 TEM morphology at the diffusion joint of. Fe3Al/Q235. For the welding of dissimilar materials, the element diffusion and phase formed at the interface of dissimilar. Table 1. Chemical composition and thermophysical properties of Fe3Al intermetallic compound. Chemical composition ...

  19. Extrinsic Curie temperature and spin reorientation changes in Nd2Fe14B/α-Fe nanocomposites

    International Nuclear Information System (INIS)

    Lewis, L.H.; Panchanathan, V.

    1998-05-01

    The Curie temperatures and spin reorientation temperatures of a series of four melt-spun nanocomposite materials comprised of Nd 2 Fe 1 4B and varying amounts of α-Fe were measured using independent techniques. The phase constitution and grain size was assessed with synchrotron x-ray diffraction; the Curie temperatures were measured by differential thermal analysis (DTA) and dc SQUID magnetometry in the temperature range 375 K ≤ T ≤ 800 K, whereas the spin reorientation transition temperature was determined from ac susceptibility measurements taken in the range 10 K ≤ T ≤ 300 K. The Curie temperature increases with increasing excess iron content, resulting in a 18 degree enhancement over the Curie temperature of pure Nd 2 Fe 14 B for 27 wt% excess α-Fe. The spin reorientation temperatures are depressed from the single-crystal value by an average of 10 degrees. Both anomalous effects are attributed to intergranular exchange coupling present in the alloys, although the effects of uncompensated stress between the constituent phases cannot be ruled out The experimental results suggest that while the Curie temperature of the Nd 2 Fe 14 B phase may be extrinsically enhanced significantly beyond the bulk value, possibly extending the range of applications of this compound, the anisotropy may be simultaneously lowered, impeding the attainment of high coercivities in these alloys

  20. Particle Surface Hydrophobicity and the Dechlorination of Chloro-Compounds by Iron Sulfides

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sang-Won, E-mail: spark3@uncc.edu; Kim, Sung-Kuk; Kim, Jeong-Bae; Choi, Sung-Woo [Keimyung University, Department of Environmental Science and Engineering (Korea, Republic of); Inyang, Hilary I. [University of North Carolina at Charlotte, Global Institute for Energy and Environmental Systems (United States); Tokunaga, Shuzo [National Institute of Advanced Industrial Science and Technology (Japan)

    2006-02-15

    Halogenated aliphatic compounds (HACs) can be reduced by iron sulfides in aqueous systems. Generally, the thermodynamics and kinetics of dehalogenation reactions are controlled by the mineralogical and particle surface characteristics of the iron sulfide, the composition of the HAC and reaction conditions such as component concentrations, pH and Eh. In this theoretical and experimental investigation of CCl{sub 4} and C{sub 2}Cl{sub 6} reduction by FeS and FeS{sub 2}, the roles of hydrophobic and hydrophilic sites on the iron sulfides were analyzed. Experimental data obtained through zeta potential measurements, were used along with the Gouy-Chapman model and the simple two-layer surface complexation model to relate iron sulfide surface hydroxyl densities to the degree of HAC dehalogenation. The surface hydroxyl site densities of FeS and FeS{sub 2} were found to be 0.11 sites/nm{sup 2} and 0.21 sites/nm{sup 2}, respectively. During the dehalogenation reaction process, CCl{sub 4} was found to decrease to its first intermediate product CHCl{sub 3} within the first 20 hours followed by a slower process of conversion to CH{sub 2}Cl{sub 2}. The results also show that FeS is less hydrated (more hydrophobic) than FeS{sub 2}. For CCl{sub 4} and C{sub 2}Cl{sub 6}, FeS is a better dehalogenator than FeS{sub 2}. These results imply that particle surface hydrophobicity is a critical factor in surface-mediated dehalogenation of chlorinated compounds.

  1. INIS: Authority list for journal titles

    International Nuclear Information System (INIS)

    2008-01-01

    This is the 34th revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). This list is published annually and includes the titles of all journals which have contained articles submitted to INIS at the time of publication. The current list contains 13 538 journal titles, 2 106 regularly scanned journals and 613 key journals. It was last updated in February 2008. A journal - or periodical - is a continuing publication issued in a succession of discrete parts, usually bearing numbering and/or chronological designations and intended to be continued indefinitely. It is generally published within a defined, fixed interval between issues and normally appears more than once per year. It includes a mixture of articles, letters, summaries, etc. Within this definition, annuals such as the Annual Review of Nuclear Science are included, but series titles such as the McGraw-Hill Series in Nuclear Engineering are not. The purpose of this document is to provide descriptive cataloguers with standard elements to include in bibliographic level 'S' of the INIS record. These elements include field (tag) 229 (Full Journal Title), 320 (ISSN) and 321 (CODEN). The full journal title is mandatory, and either the ISSN or the CODEN must be included (both may appear). Instructions on how to use this and other elements of the INIS record format are found in INIS: Guide to Bibliographic Description (IAEA-INIS-1). In order to help the user find titles easily, the list is arranged in six parts, followed by summary statistics: - In Part I, all key journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. - In Part II, all key journals are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. - In Part III, all journals that are regularly scanned by

  2. Antimony substitution in SmFeAsO

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Daniel; Braun, Hans F. [Universitaet Bayreuth (Germany)

    2015-07-01

    In the iron based compounds structural and magnetic phase transitions can be suppressed by applying external hydrostatic pressure and superconductivity emerges. Beside hydrostatic pressure, it is possible to apply chemical pressure by the substitution of atoms in the compounds with smaller ones. Such a substitution was successful for example in LaFeAs{sub 1-x}P{sub x}O, where the parent compound shows a structural and a spin-density-wave transition and the P doped samples become superconducting. We are interested in the opposite way and substitute the As by the bigger Sb. In literature, the substitution in the La-1111 compounds was possible up to a substitution level of 40 %. With Sm, instead of La, we used a smaller rare-earth metal. We present the results obtained on polycrystalline samples characterized by Xray powder diffraction and resistivity measurements.

  3. Polar and Magnetic Layered A Site and Rock Salt B Site-Ordered NaLnFeWO6 (Ln = La, Nd) Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Tetuerto, Maria [State University of New Jersey, The; Li, Mang-Rong [State University of New Jersey, The; Ignatov, Alexander [State University of New Jersey, The; Croft, Mark [State University of New Jersey, The; Ramanujachary, Kandalam V. [Rowan University; Chi, Songxue [ORNL; Hodges, Jason P [ORNL; Dachraoui, W. [University of Antwerp; Hadermann, Joke [University of Antwerp; Thao Tran, T. [University of Houston, Houston; Shiv Halasyamani, P. [University of Houston, Houston; Grams, C. [Universitat zu Koln, Koln, Germany; Hemberger, J. [Universitat zu Koln, Koln, Germany; Greenblatt, M. [State University of New Jersey, The

    2013-01-01

    We have expanded the double perovskite family of materials with the unusual combination of layered order in the A sublattice and rock salt order over the B sublattice to compounds NaLaFeWO6 and NaNdFeWO6. The materials have been synthesized and studied by powder X-ray diffraction, neutron diffraction, electron diffraction, magnetic measurements, X-ray absorption spectroscopy, dielectric measurements, and second harmonic generation. At room temperature, the crystal structures of both compounds can be defined in the noncentrosymmetric monoclinic P21 space group resulting from the combination of ordering both in the A and B sublattices, the distortion of the cell due to tilting of the octahedra, and the displacement of certain cations. The magnetic studies show that both compounds are ordered antiferromagnetically below TN 25 K for NaLaFeWO6 and at 21 K for NaNdFeWO6. The magnetic structure of NaNdFeWO6 has been solved with a propagation vector k = (1/2 0 1/2) as an antiferromagnetic arrangement of Fe and Nd moments. Although the samples are potential multiferroics, the dielectric measurements do not show a ferroelectric response.

  4. Thermodynamic Characterization of Iron Oxide-Aqueous Fe(2+) Redox Couples.

    Science.gov (United States)

    Gorski, Christopher A; Edwards, Rebecca; Sander, Michael; Hofstetter, Thomas B; Stewart, Sydney M

    2016-08-16

    Iron is present in virtually all terrestrial and aquatic environments, where it participates in redox reactions with surrounding metals, organic compounds, contaminants, and microorganisms. The rates and extent of these redox reactions strongly depend on the speciation of the Fe2+ and Fe3+ phases, although the underlying reasons remain unclear. In particular, numerous studies have observed that Fe2+ associated with iron oxide surfaces (i.e., oxide-associated Fe2+) often reduces oxidized contaminants much faster than aqueous Fe2+ alone. Here, we tested two hypotheses related to this observation by determining if solutions containing two commonly studied iron oxides—hematite and goethite—and aqueous Fe2+ reached thermodynamic equilibrium over the course of a day. We measured reduction potential (EH) values in solutions containing these oxides at different pH values and aqueous Fe2+ concentrations using mediated potentiometry. This analysis yielded standard reduction potential (EH0) values of 768 ± 1 mV for the aqueous Fe2+–goethite redox couple and 769 ± 2 mV for the aqueous Fe2+–hematite redox couple. These values were in excellent agreement with those calculated from existing thermodynamic data, and the data could be explained by the presence of an iron oxide lowering EH values of aqueous Fe3+/Fe2+ redox couples.

  5. Phase formation in the Li2MoO4–Rb2MoO4–Fe2(MoO4)3 system and crystal structure of a novel triple molybdate LiRb2Fe(MoO4)3

    International Nuclear Information System (INIS)

    Khal'baeva, Klara M.; Solodovnikov, Sergey F.; Khaikina, Elena G.; Kadyrova, Yuliya M.; Solodovnikova, Zoya A.; Basovich, Olga M.

    2013-01-01

    X-ray investigation of solid state interaction of the components in the Li 2 MoO 4 –Rb 2 MoO 4 –Fe 2 (MoO 4 ) 3 system was carried out, and a subsolidus phase diagram of the said system was constructed. The subsystem Rb 2 MoO 4 –LiRbMoO 4 –RbFe(MoO 4 ) 2 was shown to be non-quasiternary. Formation of a novel triple molybdate LiRb 2 Fe(MoO 4 ) 3 was established, conditions of solid state synthesis and crystallization of the compound were found. Its crystal structure (orthorhombic, space group Pnma, Z=4, a=24.3956(6), b=5.8306(1), c=8.4368(2) Å) represents a new structure type and includes infinite two-row ribbons ([Fe(MoO 4 ) 3 ] 3− ) ∞ parallel to the b axis and composed of FeO 6 octahedra, terminal Mo(3)O 4 tetrahedra, and bridge Mo(1)O 4 and Mo(2)O 4 tetrahedra connecting two or three FeO 6 octahedra. The ribbons are connected to form 3D framework via corner-sharing LiO 4 tetrahedra. Rubidium cations are 11- and 13-coordinated and located in cavities of this heterogeneous polyhedral framework. - Graphical abstract: Exploring the Li 2 MoO 4 –Rb 2 MoO 4 –Fe 2 (MoO 4 ) 3 system showed its partial non-quasiternarity and revealed a new compound LiRb 2 Fe(MoO 4 ) 3 which was structurally studied. - Highlights: • The Li 2 MoO 4 –Rb 2 MoO 4 –Fe 2 (MoO 4 ) 3 system study revealed a new compound LiRb 2 Fe(MoO 4 ) 3 . • Its structure of a new type includes ribbons of FeO 6 octahedra and MoO 4 tetrahedra. • The ribbons are connected into a 3D framework via corner-sharing LiO 4 tetrahedra

  6. Land Titles and Rice Production in Vietnam

    DEFF Research Database (Denmark)

    Van Den Broeck, Katleen; Newman, Carol; Tarp, Finn

    In most of the empirical literature on land titling, the household is regarded as unitary, and land rights are found to have ambiguous effects on land allocation, investment and productivity. Using data from 12 provinces in Vietnam, we diversify land titles, and show in a household fixed effects...... analysis of plot level rice yields that land titles are indeed important. Only exclusively held titles have the expected positive effects, and the positive effect on yields is found in male headed households. Furthermore, a household level rice yield function reveals that exclusive user rights...... are inefficiency decreasing, while jointly held user rights have no efficiency effects. Finally, once the gender of the head of household is controlled for, exclusively held female titles have a greater positive effect on the efficiency of the household than that of male held titles...

  7. Cell-free H-cluster synthesis and [FeFe] hydrogenase activation: all five CO and CN⁻ ligands derive from tyrosine.

    Directory of Open Access Journals (Sweden)

    Jon M Kuchenreuther

    Full Text Available [FeFe] hydrogenases are promising catalysts for producing hydrogen as a sustainable fuel and chemical feedstock, and they also serve as paradigms for biomimetic hydrogen-evolving compounds. Hydrogen formation is catalyzed by the H-cluster, a unique iron-based cofactor requiring three carbon monoxide (CO and two cyanide (CN⁻ ligands as well as a dithiolate bridge. Three accessory proteins (HydE, HydF, and HydG are presumably responsible for assembling and installing the H-cluster, yet their precise roles and the biosynthetic pathway have yet to be fully defined. In this report, we describe effective cell-free methods for investigating H-cluster synthesis and [FeFe] hydrogenase activation. Combining isotopic labeling with FTIR spectroscopy, we conclusively show that each of the CO and CN⁻ ligands derive respectively from the carboxylate and amino substituents of tyrosine. Such in vitro systems with reconstituted pathways comprise a versatile approach for studying biosynthetic mechanisms, and this work marks a significant step towards an understanding of both the protein-protein interactions and complex reactions required for H-cluster assembly and hydrogenase maturation.

  8. Large magnetic entropy change in melt-spun LaFe11.5Si1.5 ribbons

    International Nuclear Information System (INIS)

    Xie Kun; Song Xiaoping; Zhu Yaoming; Lv Weipeng; Sun Zhanbo

    2004-01-01

    The microstructure transformation and the magnetic entropy change of LaFe 11.5 Si 1.5 melt-spun ribbons were investigated. The melt-spun ribbons show a homogeneous distribution of elements, and the homogeneity develops further after 5 h annealing. XRD results show that the ribbons are composed of NaZn 13 -type LaFe 11.5 Si 1.5 compounds and an α-Fe phase. After annealing, the ribbons crystallize well in the NaZn 13 -type structure and exhibit a very large magnetic entropy change. A first-order magnetic transition is observed in the annealed ribbons, and this is believed to be the origin of the large magnetic entropy. These results suggest that NaZn 13 -type LaFe 11.5 Si 1.5 compounds with a large magnetic entropy change can be produced by melt-spinning, the annealing time can be shortened significantly and the production cost of the magnetic refrigerant will be cut down accordingly

  9. Optimization of the crystal growth of the superconductor CaKFe4As4 from solution in the FeAs -CaFe2As2-KFe2As2 system

    Science.gov (United States)

    Meier, W. R.; Kong, T.; Bud'ko, S. L.; Canfield, P. C.

    2017-06-01

    Measurements of the anisotropic properties of single crystals play a crucial role in probing the physics of new materials. Determining a growth protocol that yields suitable high-quality single crystals can be particularly challenging for multicomponent compounds. Here we present a case study of how we refined a procedure to grow single crystals of CaKFe4As4 from a high temperature, quaternary liquid solution rich in iron and arsenic ("FeAs self-flux"). Temperature dependent resistance and magnetization measurements are emphasized, in addition to the x-ray diffraction, to detect intergrown CaKFe4As4 , CaFe2As2 , and KFe2As2 within what appear to be single crystals. Guided by the rules of phase equilibria and these data, we adjusted growth parameters to suppress formation of the impurity phases. The resulting optimized procedure yielded phase-pure single crystals of CaKFe4As4 . This optimization process offers insight into the growth of quaternary compounds and a glimpse of the four-component phase diagram in the pseudoternary FeAs -CaFe2As2-KFe2As2 system.

  10. Effects of the defects on the structural, electronic and magnetic properties of Sr{sub 2}FeMoO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yan, E-mail: yan.zhang@chd.edu.cn [School of Materials Science and Engineering, Chang' an University, Xi' an 710061, Shaanxi (China); Ji, Vincent [ICMMO/SP2M, UMR CNRS 8182, Université Paris-Sud, 91405 Orsay Cédex (France); Xu, Ke-Wei [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China)

    2015-11-05

    From the point of view of the half-metallic character and magnetization reduction, the structural, electronic and magnetic properties of the imperfect Sr{sub 2}FeMoO{sub 6} compound containing seven different defects of the Fe{sub Mo} or Mo{sub Fe} antisites, Fe–Mo interchange, V{sub Fe}, V{sub Mo}, V{sub O} or V{sub Sr} vacancies have been studied by using first-principles projector augmented wave (PAW) within generalized gradient approximation (GGA) as well as taking into account on-site Coulomb repulsive interaction (GGA + U). No obvious structural changes are observed for the imperfect Sr{sub 2}FeMoO{sub 6} compound containing Fe{sub Mo} or Mo{sub Fe} antisites, Fe–Mo interchange or V{sub Sr} vacancy defects. However, the six (eight) nearest oxygen neighbors of the vacancy move away from (close to) V{sub Fe} or V{sub Mo} (V{sub O}) vacancies. The half-metallic character is maintained for the imperfect Sr{sub 2}FeMoO{sub 6} compound containing Fe{sub Mo} antisite, V{sub Fe}, V{sub O} or V{sub Sr} vacancies, while it vanishes when Mo{sub Fe} antisite, Fe–Mo interchange or V{sub Mo} vacancy are presented. So the Mo{sub Fe} antisite, Fe–Mo interchange or V{sub Mo} vacancy defects have to be avoided in order to preserve the half-metallic character of the Sr{sub 2}FeMoO{sub 6} compound and thus usable in spintronics devices. In Fe{sub Mo} or Mo{sub Fe} antisites, Fe–Mo interchange cases, the spin moments of Fe (Mo) cations situated on Mo (Fe) antisites are in an antiferromagnetic coupling with those of Fe (Mo) cations on the regular sites. In V{sub Fe}, V{sub Mo}, V{sub O} or V{sub Sr} vacancies cases, a ferromagnetic coupling is obtained within each cation sublattice, while two cation sublattices are coupled antiferromagnetically. The total magnetic moments μ{sub tot} (μ{sub B}/f.u.) of the imperfect Sr{sub 2}FeMoO{sub 6} compound containing seven different defects decrease in the sequence of V{sub Sr} vacancy (4.38), V{sub Mo} vacancy (3.92), V{sub O

  11. 3d-metal doping (Fe,Co,Ni,Zn) of the high T/sub c/ perovskite YBa/sub 2/Cu/sub 3/O/sub 7-y/

    International Nuclear Information System (INIS)

    Tarascon, J.M.; Barboux, P.; Greene, L.H.; Hull, G.W.; Bagley, B.G.

    1988-01-01

    The structural, magnetic and superconducting properties of the mixed compounds YBa/sub 2/Cu/sub 3-x/M/sub x/O/sub 7-y/ (M = Ni, Zn, Fe and Co) are reported. Values of y, determined by titration, are found to be dependent on the nature and amount of the doping. The range of solubility is greater for the Fe and Co compounds (chi = 1) than for those with Ni or Zn (chi = 0.3). The undoped material is orthorhombic and remains orthorhombic after substitution for Cu by Ni or Zn, whereas a tetragonal phase is observed when Fe, Co are substituted for Cu. DC resistance and AC susceptibility measurements show that T/sub c/ is depressed from 90K (chi = 0) to 45K (chi = 0.2) for both the Ni and Zn doped compounds and T/sub c/ is destroyed in the Fe and Co doped compounds when chi reaches 0.4. The authors suggest that a valance of 2 be assigned to the Ni and Zn and 3 to the Fe and Co ions

  12. Thermodynamic properties of compounds of Na2O with the oxides of chromium, nickel, and iron

    International Nuclear Information System (INIS)

    Shaiu, B.J.

    1976-10-01

    Results of emf measurements on Na 2 O solid electrolytes in binary compounds with Cr 2 O 3 , FeO, and NiO are presented along with thermodynamic properties of these compounds. It was found that reliable thermodynamic data for compounds of NaCrO 2 , Na 2 FeO 2 , NaFeO 2 , Na 2 NiO 2 , and NaNiO 2 at 500 to 800 0 can be obtained by using emf measurements with solid electrolyte cells. The pretreatment of heating the cells in a vacuum of 10 -2 torr at 500 0 C or above for about 12 hours causes the emf dependence on temperature to be very small. The measurements were carried out over the temperature range in which no phase transformations occurred, the ΔC/sub p/ for the compounds involved was reasonably considered as approximately zero. Linear emf-temperature plots were therefore expected for these cells and the equation of ΔG 0 /sub f/ was indeed valid for constant values of ΔH 0 /sub f/ and ΔS 0 /sub f/. The formation of compound NaCrO 2 is thermodynamically favorable in a sodium loop made of austenic stainless steels. The critical oxygen concentration for the formation of NaCrO 2 shows that it is stable in liquid sodium in temperature range from 400 to 1100 0 C and Cr 2 O 3 does not exist with the double oxide in liquid sodium. The existence temperature for (Na 2 O) 2 .FeO in equilibrium with oxygen saturated liquid sodium is 693 0 K or above, for Na 2 FeO 2 it is 1141 0 K or above and for NaFeO 2 it is greater than or equal to 1173 0 K. The double oxides of nickel with sodium oxide are much less stable than the iron double oxides and do therefore not exist in liquid sodium. The nickel in austenitic stainless steel shows the least attack by oxygen saturated liquid sodium

  13. Effects of Nb content on the Zr2Fe intermetallic stability

    International Nuclear Information System (INIS)

    Ramos, C.; Saragovi, C.; Granovsky, M.; Arias, D.

    2003-01-01

    With the aim of studying the stability range of the Zr 2 Fe intermetallic when adding Nb, the range of existence of the cubic ternary phase (λ 1 ) and the corresponding two-phase field between them, four samples were analyzed, each one containing 35 at.% Fe and different at.% Nb: 0.5, 4 10 and 15. Optical and scanning electron metallographies, X-ray diffraction, microprobe analysis and Moessbauer spectroscopy were performed to determine and characterize the phases present in the samples. Results show that the Zr 2 Fe compound accepts up to nearly 0.5 at.% Nb in solution, since the Zr 2 Fe+λ 1 region is stable in the (0.5-3.5) at.% Nb range. To summarize these results an 800 deg. C section of the ternary Zr-Nb-Fe diagram, in the studied zone, was proposed

  14. Formation of 3-monochloro-1,2-propanediol (3-MCPD) di- and monoesters from tristearoylglycerol (TSG) and the potential catalytic effect of Fe²⁺ and Fe³⁺.

    Science.gov (United States)

    Zhang, Zhongfei; Gao, Boyan; Zhang, Xiaowei; Jiang, Yuanrong; Xu, Xuebing; Yu, Liangli Lucy

    2015-02-18

    This study investigated whether and how triacylglycerol (TAG) may serve as a precursor for 3-monochloro-1,2-propanediol (3-MCPD) fatty acid ester formation using tristearoylglycerol (TSG). TSG was reacted with inorganic chloride compounds including NaCl, KCl, FeCl2, CuCl2, ZnCl2, FeCl3 and dry HCl, or organic chlorine compound lindane at different temperatures. Only FeCl2 and FeCl3 were able to form 3-MCPD esters from TSG. Further electron spin resonance (ESR) determination of TSG, Fe2(SO4)3 and 5,5-dimethylpyrroline-N-oxide (DMPO) reactions revealed potential of Fe ion in promoting free radical generations under the experimental conditions. To further confirm the effect of Fe ion, chelating agent (EDTA-2Na) was added to the model reactions. The results showed for the first time that EDTA-2Na was able to reduce the generation of 3-MCPD esters. In addition, FT-IR examination indicated a possible involvement of a carbonyl group during the reaction. Taking all the observations together, the possible mechanisms, involving the formation of either a cyclic acyloxonium or a glycidol ester radical intermediate, were proposed for generating 3-MCPD fatty acid di- and mono- esters from TAG under a high temperature and low moisture condition, as well as the coformation of glycidol esters. The results from this study may be useful for reducing the level of 3-MCPD esters and related toxicants in the refined edible oils and food products.

  15. Effect of Organic Substances on the Efficiency of Fe(Ii to Fe(Iii Oxidation and Removal of Iron Compounds from Groundwater in the Sedimentation Process

    Directory of Open Access Journals (Sweden)

    Krupińska Izabela

    2017-09-01

    Full Text Available One of the problems with iron removal from groundwater is organic matter. The article presents the experiments involved groundwater samples with a high concentration of total iron - amounting to 7.20 mgFe/dm3 and an increased amount of organic substances (TOC from 5.50 to 7.50 mgC/dm3. The water samples examined differed in terms of the value of the ratio of the TOC concentration and the concentration of total iron (D. It was concluded that with increase in the coexistence ratio of organic substances and total iron in water (D = [TOC]/[Fetot], efficiency of Fe(II to Fe(III oxidization with dissolved oxygen decreased, while the oxidation time was increasing. This rule was not demonstrated for potassium manganate (VII when used as an oxidizing agent. The application of potassium manganate (VII for oxidation of Fe(II ions produced the better results in terms of total iron concentration reduction in the sedimentation process than the oxidation with dissolved oxygen.

  16. Effect of Organic Substances on the Efficiency of Fe(Ii) to Fe(Iii) Oxidation and Removal of Iron Compounds from Groundwater in the Sedimentation Process

    Science.gov (United States)

    Krupińska, Izabela

    2017-09-01

    One of the problems with iron removal from groundwater is organic matter. The article presents the experiments involved groundwater samples with a high concentration of total iron - amounting to 7.20 mgFe/dm3 and an increased amount of organic substances (TOC from 5.50 to 7.50 mgC/dm3). The water samples examined differed in terms of the value of the ratio of the TOC concentration and the concentration of total iron (D). It was concluded that with increase in the coexistence ratio of organic substances and total iron in water (D = [TOC]/[Fetot]), efficiency of Fe(II) to Fe(III) oxidization with dissolved oxygen decreased, while the oxidation time was increasing. This rule was not demonstrated for potassium manganate (VII) when used as an oxidizing agent. The application of potassium manganate (VII) for oxidation of Fe(II) ions produced the better results in terms of total iron concentration reduction in the sedimentation process than the oxidation with dissolved oxygen.

  17. Dimensionality and magnetic interactions in CaFe2As2: An ab initio study

    International Nuclear Information System (INIS)

    Tompsett, D.A.; Lonzarich, G.G.

    2010-01-01

    We present detailed electronic structure calculations for CaFe 2 As 2 . We investigate in particular the 'collapsed' tetragonal and orthorhombic regions of the temperature-pressure phase diagram and find properties that distinguish CaFe 2 As 2 from other Fe-pnictide compounds. In contrast to the tetragonal phase of other Fe-pnictides the electronic structure in the 'collapsed' tetragonal phase of CaFe 2 As 2 is found to be strongly 3D. By an analysis of the non-interacting susceptibility, χ 0 (q), of CaFe 2 As 2 and LaFePO we discuss the role of magnetic interactions in iron-pnictides. From this we propose an intuitive explanation for the outstanding question relating to why the predicted antiferromagnetic moment depends strongly on coordinate relaxation and the choice of correlation functional.

  18. Ion-beam mixing and solid-state reaction in Zr-Fe multilayers

    International Nuclear Information System (INIS)

    Paesano, A. Jr.; Motta, A.T.; Birtcher, R.C.; Ryan, E.A.; Teixeira, S.R.; Bruckmann, M.E.; Amaral, L.

    1997-01-01

    Vapor-deposited Zr-Fe multilayered thin films with various wavelengths and of overall composition either 50% Fe or Fe-rich up to 57% Fe were either irradiated with 300 keV Kr ions at temperatures from 25 K to 623 K to fluences up to 2 x 10 16 cm -2 , or simply annealed at 773 K in-situ in the Intermediate Voltage Electron microscope At Argonne National Laboratory. Under irradiation, the final reaction product is the amorphous phase in all cases studied, but the dose to amorphization depends on the temperature and on the wavelength. In the purely thermal case (annealing at 773 K), the 50-50 composition produces the amorphous phase but for the Fe-rich multilayers the reaction products depend on the multilayer wavelength. For small wavelength, the amorphous phase is still formed, but at large wavelength the Zr-Fe crystalline intermetallic compounds appear. These results are discussed in terms of existing models of irradiation kinetics and phase selection during solid state reaction

  19. Crystal structure of tri­chlorido­(4'-ferrocenyl-2,2':6',2''-terpyridine-[kappa]3N,N',N'')iridium(III) aceto­nitrile disolvate

    KAUST Repository

    Davaasuren, Bambar; Padhy, Harihara; Rothenberger, Alexander

    2015-01-01

    In the title compound, [FeIr(C5H5)(C20H14N3)Cl3]·2CH3CN, the central IrIII atom is sixfold coordinated by three chloride ligands and three terpyridine N atoms in a slightly distorted octa­hedral fashion. The terpyridine ligand is functionalized

  20. Quarterly title list for the period ending June 1980

    International Nuclear Information System (INIS)

    1980-01-01

    The title list contains: a) 17 titles and abstracts of laboratory reports, b) 36 titles of publications (32 with abstracts), c) 13 titles of articles submitted for publication (12 with abstracts), and d) 72 titles of lectures (52 with abstracts.) (GG) [de

  1. Magnetic properties and tunable magneto-caloric effect in La0.8Ce0.2Fe11.5-xCoxSi1.5C0.2 (x = 0.3, 0.5, and 0.7) compounds

    Science.gov (United States)

    Wu, Qiming; Wang, Xiangjie; Ding, Zan; Li, Lingwei

    2018-05-01

    The magnetic and magneto-caloric properties in the ternary elementals doped La0.8Ce0.2Fe11.5-xCoxSi1.5C0.2 (x = 0.3, 0.5, and 0.7) compounds were studied. With the increases of Co content x, the Curie temperature TC increases and the thermal hysteresis decreases. All the compounds undergo a second-order magnetic phase transition and exhibit a considerable reversible tunable magneto-caloric effect. The values of maximum magnetic entropy change (-ΔSMmax) and the Relative Cooling Power (RCP) are kept at same high level with different Co content. Under a magnetic field change of 0-5 T, the values of -ΔSMmax for La0.8Ce0.2Fe11.5-xCoxSi1.5C0.2 are 10.5, 10.7, and 9.8 J/kg K for x = 0.3, 0.5, and 0.7, respectively. The corresponding values of RCP are 267.1, 289.9, and 290.2 J/kg.

  2. Synthesis and anomalous magnetic properties of LaFeO{sub 3} nanoparticles by hot soap method

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Tatsuo, E-mail: tfujii@cc.okayama-u.ac.jp [Department of Applied Chemistry, Okayama University, Tsushima-naka 3-1-1, Okayama 700-8530 (Japan); Matsusue, Ikkoh; Nakatsuka, Daisuke; Nakanishi, Makoto; Takada, Jun [Department of Applied Chemistry, Okayama University, Tsushima-naka 3-1-1, Okayama 700-8530 (Japan)

    2011-10-03

    Highlights: {yields} Nanocrystalline LaFeO{sub 3} particles were synthesized by using hot soap technique. {yields} Average diameter of the obtained LaFeO{sub 3} nanoparticles was about 15 nm. {yields} They exhibited superparamagnetic behavior with a blocking temperature of 30 K. {yields} Large magnetization due to the presence of uncompensated surface spins was induced. - Abstract: Nanocrystalline LaFeO{sub 3} particles were synthesized at low temperatures by using hot soap technique. The synthesis was based on the thermal decomposition of organometallic compounds precipitated in a hot coordinating solvent. Moderate heat treatment at low temperature far below the combustion point of organic compounds produced spherical LaFeO{sub 3} nanoparticles with average diameter of about 15 nm. The crystalline phase, structure and particle size of obtained products were characterized by X-ray diffraction, infrared spectroscopy and transmission electron microscopy observations. In spite of the antiferromagnetic nature of bulk LaFeO{sub 3}, the obtained nanoparticles exhibited anomalous large magnetization. Superparamagnetic behavior with a blocking temperature of about 30 K was observed in both magnetization and Moessbauer spectroscopic analyses.

  3. Title of the paper goes here second line

    Indian Academy of Sciences (India)

    %%Please download if these packages are not included %%in your local TeX distribution %%txfonts,balance,textcase,float %% \\begin{document} %%paper title %%For line breaks, \\\\ can be used within title \\title{Title of the paper goes here\\\\ second line} %%author names are separated by comma (,) %%use \\and before ...

  4. Magnetisation and AC susceptibility studies of La1-xSrxFe0.8Cr0.2O3-δ (0.0

    International Nuclear Information System (INIS)

    Ferreira, L.P.; Cruz, M.M.; Ramos, T.; Sa, M.A.; Carvalho, M.D.; Godinho, M.

    2007-01-01

    Magnetisation and AC magnetic susceptibility measurements have been performed in the perovskite-type compounds La 1-x Sr x Fe 0.8 Cr 0.2 O 3-δ (x=0.2, 0.4, 0.6 and 0.8). All compounds show an overall antiferromagnetic behaviour mainly attributed to predominant Fe 3+ -O-Fe 3+ interactions. For 0.2 ord . The coexistence of AFM and FM interactions leads to reentrant magnetic behaviour for the x=0.4 compound and to spin-glass like behaviour for x=0.8. Between x=0.6 and 0.8, the similar magnetic moments found in the paramagnetic region indicate that the Fe/Cr valences do not change significantly, pointing towards an increased role for oxygen vacancy formation in the charge compensation mechanism

  5. Electronic structure of BaFe2As2 as obtained from DFT/ASW first-principles calculations

    KAUST Repository

    Schwingenschlö gl, Udo; Di Paola, Cono

    2010-01-01

    We use ab-initio calculations based on the augmented spherical wave method within density functional theory to study the magnetic ordering and Fermi surface of BaFe2As2, the parent compound of the hole-doped iron pnictide superconductors (K,Ba)Fe2As

  6. Structural and magnetic properties of Nd0.67Ba0.33MnO3 manganites with partial replacement of Fe and Cu at Mn-site

    Science.gov (United States)

    Sudakshina, B.; Arun, B.; Chandrasekhar, K. Devi; Yang, H. D.; Vasundhara, M.

    2018-06-01

    We have investigated the structural and magnetic properties of Nd0.67Ba0.33MnO3 manganite and partial replacement of Mn with Fe and Cu compounds followed by X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS) and vibrating sample magnetometer (VSM). The Rietveld refinement of XRD indicates orthorhombic crystal structure with I-mma space group for all the compounds and thus obtained lattice parameters confirm the presence of co-operative Jahn-Teller effect. XRD and XAS spectra results suggests the existence of Fe3+ in Fe-substituted compound where as a mixed state of Cu2+ and Cu3+ ions in the Cu-substituted compound. The ferromagnetic (FM) to paramagnetic (PM) transition and magnetic moment is found to decrease upon the substitution of Fe and Cu atoms because of the suppression of double exchange interaction. The theoretically obtained and experimentally determined values of effective PM moment and saturation magnetic moment confirms the presence of inhomogeneous magnetic states containing FM and antiferromagnetic clusters in all the studied compounds.

  7. Ab initio study on half-metallic, electronic and thermodynamic attributes of LaFeO3

    Science.gov (United States)

    Tariq, Saad; Saad, Saher; Jamil, M. Imran; Sohail Gilani, S. M.; Mahmood Ramay, Shahid; Mahmood, Asif

    2018-03-01

    By using the density functional theory (DFT) the systematic study of the structural, electronic and thermodynamic properties of lanthanum ferrite (LaFeO3) has been conducted. The elastic stability criterion and structural tolerance factor reveal that LaFeO3 exists in the cubic phase and is found to be stable under the ambient conditions. In electronic properties, the optical spectrum of the compound has been found to fall in the range of 488 to 688nm which has been calculated from the electronic band gap values by using the PBE-GGA and mBJ-GGA techniques. The light between 488 to 688nm would cause the valence electrons to jump in the conduction band showing the photoconductivity. The pronounced half-metallic character has been discussed by using the projected electronic density of states. The ferromagnetic response has been observed which may be attributed to the Fe-O bonding situation. The compound exhibits ductile, indirect band gap and half-metallic traits in the bulk phase. We expect the compound to be felicitous for the novel spintronic applications.

  8. Absence of evidence of decomposition of Fe2B during mechanical grinding

    International Nuclear Information System (INIS)

    Balogh, J.; Horvath, Z.E.; Pusztai, T.; Kemeny, T.; Vincze, I.

    1998-01-01

    The appearance of bcc Fe after grinding Fe 2 B for a long time has been formerly interpreted as being due to the decomposition of the thermodynamically stable intermetallic compound when the crystallite size is reduced to a few nanometers. The results of our control experiments performed by tungsten-carbide milling tools show that the appearance of bcc Fe has no relation to the grain size but should be connected to contamination when tools made of steel are used to pulverize this material. Moessbauer spectroscopy was applied to search for the appearance of bcc Fe while changes in the grain size were checked by x-ray diffraction and transmission electron microscopy. copyright 1998 The American Physical Society

  9. Influence of hydrogenation and mechanical grinding on the structural and ferromagnetic properties of GdFeSi

    Energy Technology Data Exchange (ETDEWEB)

    Chevalier, Bernard; Duttine, Mathieu; Wattiaux, Alain [Universite de Bordeaux, CNRS ICMCB, Pessac (France)

    2016-08-01

    Hydrogen insertion into GdFeSi induces (i) a structural transition from a tetragonal CeFeSi-type to a tetragonal ZrCuSiAs-type, (ii) an anisotropic expansion of the unit cell parameters because the a parameter decreases, whereas the c parameter increases, and (iii) a decrease in Curie temperature from 121 to 20 K. On the contrary, an amorphous ferromagnet (T{sub C} = 65 K) is obtained by mechanical grinding of GdFeSi. The three compounds (GdFeSi, GdFeSiH, and amorphous GdFeSi) were investigated by {sup 57}Fe Moessbauer spectroscopy. At 4.2 K, this study has revealed that the magnetically ordered Gd substructure produces a small transferred hyperfine magnetic field at the {sup 57}Fe nucleus.

  10. STRUCTURE AND SOME BIOLOGICAL PROPERTIES OF Fe(III COMPLEXES WITH NITROGEN-CONTAINING LIGANDS

    Directory of Open Access Journals (Sweden)

    Ion Bulhac

    2016-06-01

    Full Text Available Four coordination compounds of iron(III with ligands based on hydrazine and sulfadiazine: FeCl3·digsemi·2H2O (I (digsemi-semicarbazide diacetic acid dihydrazide, [Fe(HLSO4] (II (НL - sulfadiazine, [Fe(H2L1(H2O2](NO33·5H2O (III (H2L1-2,6-diacetylpyridine bis(nicotinoylhydrazone and [Fe(H2L2(H2O2](NO33•1.5H2O (IV (H2L2 - 2,6-diacetylpyridine bis(isonicotinoylhydrazone were synthesized. The spectroscopic and structural characterisation as well as their biological, properties are presented.

  11. Development of compound layer during nitriding and nitrocarburising; current status and future challenges

    DEFF Research Database (Denmark)

    Somers, Marcel A. J.

    2011-01-01

    The development of the compound layer during gaseous nitriding and nitrocarburising of Fe based material is described. The first nucleation of the compound layer at the surface depends on the competition between the dissociation of ammonia and the removal of nitrogen from the surface by solid sta...

  12. Structure and magnetic properties of the 3d transition-metal mono-borides TM–B (TM=Mn, Fe, Co) under pressures

    International Nuclear Information System (INIS)

    Bourourou, Y.; Beldi, L.; Bentria, B.; Gueddouh, A.; Bouhafs, B.

    2014-01-01

    In this paper, spin-polarization and pressure effects on the structural and electronic properties of the 3d transition-metal mono-borides TM–B (TM=Mn, Fe, Co) have been studied by using both local spin-density approximation (LSDA) and generalized gradient approximation (GGA) within the framework of density-functional theory (DFT). At equilibrium, spin-polarization calculations show that MnB and FeB compounds carry magnetic moment. The non-spin-polarization results show that the non-magnetic state is unstable for MnB and FeB compounds, but a stable non-magnetic phase for CoB compound, which is discussed in the framework of the well-known Stoner criterion. The calculated lattice parameters, bulk moduli, their first-pressure derivatives and magnetic moments agree well with experimental and other theoretical results. Significant differences in volume and in bulk modulus were found between the magnetic and non-magnetic case reached 4%, 22%, respectively. The effect of pressure on the crystal structure reflects in a compression of the unit cell volume with a decreasing in the magnetic moment. The density of states of MnB and FeB ferromagnetic compounds are significantly modified under high pressures. The exchange energy decreases with increasing pressure, at approximately V/V 0 =0.6, the exchange energy becomes absent in ferromagnetic compounds causes mirror in upper and lowers half panels. Finally, we notice that spin-polarization and pressure play a crucially important role in determining the electronic and structural properties of 3d transition-metal mono-borides. - Highlights: • Spin polarization and pressure effects on TM–B (TM=Mn, Fe, Co) have been investigated. • The non-spin-polarization results show that the non-magnetic state is stable for CoB. • The magnetic states of MnB and FeB are found more stable than their nonmagnetic states. • We report significant differences between the magnetic and non-magnetic cases. • The density of states of MnB and

  13. Organic radionuclide compounds in soil solutions and their role in elements absorption in plants

    International Nuclear Information System (INIS)

    Agapkin, G.I.; Tikhomirov, F.A.

    1991-01-01

    The results of reference experiments with introduction of radioactive labels ( 35 S, 45 Ca, 59 Fe, 85 , 125 I) into 5 types of climatophytic soils by the method of radiogel-chromatography allow to ascertain that in soil solutions 59 Fe and 125 I incorporate completely and 35 S, 45 Ca and 85 Sr incorporate by 60-90 % into the composition of one of three fractions of organic compounds with molecular masses of 4x10 2 -6x10 4 . It is shown that significant variations between soils in the absorption of such radionuclides as 4 5 Ca, 58 Fe, 85 Sr and 125 I are celated to a different degree of their transport into soil solutions as well as to differencies in their distribution by molecular-mass fractions of water-soluble organic compounds

  14. INIS: Authority list for journal titles

    International Nuclear Information System (INIS)

    2009-01-01

    This is the 35th revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). This list is published annually and includes the titles of all journals which have contained articles submitted to INIS at the time of publication. The current list contains 13 750 journal titles, 1 965 regularly scanned journals and 593 key journals. It was last updated in March 2009. A journal - or periodical - is a continuing publication issued in a succession of discrete parts, usually bearing numbering and/or chronological designations and intended to be continued indefinitely. It is generally published within a defined, fixed interval between issues and normally appears more than once per year. It includes a mixture of articles, letters, summaries, etc. Within this definition, annuals such as the Annual Review of Nuclear Science are included, but series titles such as the McGraw-Hill Series in Nuclear Engineering are not. The purpose of this document is to provide descriptive cataloguers with standard elements to include in bibliographic level 'S' of the INIS record. These elements include field (tag) 229 (Full Journal Title), 320 (ISSN) and 321 (CODEN). The full journal title is mandatory, and either the ISSN or the CODEN must be included (both may appear). Instructions on how to use this and other elements of the INIS record format are found in INIS: Guide to Bibliographic Description (IAEA-INIS-1). In order to help the user find titles easily, the list is arranged in six parts, followed by summary statistics: - In Part I, all key journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. - In Part II, all key journals are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. - In Part III, all journals that are regularly scanned by the

  15. Spin dynamics in the strongly magnetically frustrated compounds YBaCo{sub 3}AlO{sub 7} and YBaCo{sub 3}FeO{sub 7} probed by NMR and ESR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Iakovleva, Margarita [IFW Dresden, Dresden (Germany); TU Dresden, Dresden (Germany); E. K. Zavoisky Physical-Technical Institute, Kazan (Russian Federation); Zeisner, Julian; Zimmermann, Stephan; Buechner, Bernd [IFW Dresden, Dresden (Germany); TU Dresden, Dresden (Germany); Valldor, Martin [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Dresden (Germany); Vavilova, Evgeniia [E. K. Zavoisky Physical-Technical Institute, Kazan (Russian Federation); Grafe, Hans-Joachim; Alfonsov, Alexey; Kataev, Vladislav [IFW Dresden, Dresden (Germany)

    2016-07-01

    In the Swedenborgite type compounds YBaCo{sub 3}AlO{sub 7} and YBaCo{sub 3}FeO{sub 7} the magnetic lattice can be described as a stacking of kagome layers, where unconventional ground states such as a spin liquid state can be expected due to the strong geometrical frustration. We performed a combined experimental study of magnetic properties of single crystals of YBaCo{sub 3}AlO{sub 7} and YBaCo{sub 3}FeO{sub 7} with high field ESR and high field NMR spectroscopy. The experimental results show the occurrence of short-range quasi static electron spin correlations at T{sup *} ∼ 22 K for YBaCo{sub 3}AlO{sub 7} and T{sup *} ∼ 60K for YBaCo{sub 3}FeO{sub 7} but not a long-range antiferromagnetic order. We compare our results with AC and DC susceptibility measurements and discuss a possible competition between a spin glass-like state due to intrinsic structural disorder and a spin liquid state arising from strong magnetic frustration in this materials.

  16. Magnetic-entropy change in Mn1.1Fe0.9P0.7As0.3-xGe x

    International Nuclear Information System (INIS)

    Tegus, O.; Fuquan, B.; Dagula, W.; Zhang, L.; Brueck, E.; Si, P.Z.; Boer, F.R. de; Buschow, K.H.J.

    2005-01-01

    We have studied the magnetic properties and magnetic-entropy changes of Mn 1.1 Fe 0.9 P 0.7 As 0.3-x Ge x compounds with x = 0, 0.05, 0.1, 0.15 and 0.3. X-ray diffraction (XRD) study shows all the compounds crystallize in the Fe 2 P-type structure. Magnetic measurements show that the Curie temperature increases from 150 K for Mn 1.1 Fe 0.9 P 0.7 As 0.3 to 380 K for Mn 1.1 Fe 0.9 P 0.7 Ge 0.3 . A field-induced first-order magnetic phase transition is observed above the Curie temperature for the compounds with x up to 0.15. There exists an optimal composition in which the first-order phase transition is the sharpest. The optimal composition for this system is x = 0.1. The maximal magnetic-entropy change derived from the magnetization data is about 40 J/(kg K) for a field change from 0 to 3 T

  17. 24 CFR 203.385 - Types of satisfactory title evidence.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Types of satisfactory title... Title Waivers § 203.385 Types of satisfactory title evidence. The following types of title evidence shall be satisfactory to the Commissioner: (a) Fee or owner's title policy. A fee or owner's policy of...

  18. Study of the CMR compounds in hazardous wastes

    International Nuclear Information System (INIS)

    Chollot, A.

    2007-01-01

    In order to limit the exposure of workers to carcinogenic, mutagen and reproduction-toxic compounds (CMR) and to optimize the safety needs in the field of hazardous industrial wastes, the INRS has decided to complete its knowledge in doing a sectorial inquiry titled 'study of the CMR compounds contained in wastes'. This study allows to obtain data relative to hazardous wastes and to the presence of CMR compounds into these hazardous wastes. The first part of this study gives the methodology used for doing this inquiry. The results, gathered in databases, are presented in tables and in synthetic schemes. The last part gives operational propositions it could be important to adopt to improve and/or to develop safety approaches adapted to the CMR risk and, particularly the transfer of the good data to workers. (O.M.)

  19. Reactivity of Cubane-Type [(OC)(3)MFe(3)S(4)(SR)(3)](3-) Clusters (M = Mo, W): Interconversion with Cuboidal [Fe(3)S(4)](0) Clusters and Electron Transfer.

    Science.gov (United States)

    Raebiger, James W.; Crawford, Charles A.; Zhou, Jian; Holm, R. H.

    1997-03-12

    The title clusters, several examples of which have been reported earlier, have been prepared by two different methods and subjected to structural and reactivity studies. The compounds (Et(4)N)(3)[(OC)(3)MFe(3)S(4)(Smes)(3)].MeCN (M = Mo/W) are isomorphous and crystallize in monoclinic space group P2(1)/n with a = 13.412(1)/13.297(1) Å, b = 19.0380(1)/18.9376(3) Å, c = 26.4210(1)/26.2949(1) Å, beta = 97.87(1)/97.549(1) degrees, and Z = 4. The clusters contain long M-S (2.62/2.59 Å) and M-Fe (3.22/3.19 Å) bonds, consistent with the reported structure of [(OC)(3)MoFe(3)S(4)(SEt)(3)](3-) (3). Reaction of [(OC)(3)MoFe(3)S(4)(LS(3))](3-) (7) with CO in the presence of NaPF(6) affords cuboidal [Fe(3)S(4)(LS(3))](3-) (9), also prepared in this laboratory by another route as a synthetic analogue of protein-bound [Fe(3)S(4)](0) clusters. The clusters [Fe(3)S(4)(SR)(3)](3-) (R = mes, Et), of limited stability, were generated by the same reaction. Treatment of 9 with [M(CO)(3)(MeCN)(3)] affords 7 and its M = W analogue. The clusters [(OC)(3)MFe(3)S(4)(SR)(3)](3-) form a four-member electron transfer series in which the 3- cluster can be once reduced (4-) and twice oxidized (2-, 1-) to afford clusters of the indicated charges. The correct assignment of redox couple to potential in the redox series of six clusters is presented, correcting an earlier misassignment of the redox series of 3. Carbonyl stretching frequencies are shown to be sensitive to cluster oxidation state, showing that the M sites and Fe(3)S(4) fragments are electronically coupled despite the long bond distances. (LS(3) = 1,3,5-tris((4,6-dimethyl-3-mercaptophenyl)thio)-2,4,6-tris(p-tolylthio)benzenate(3-); mes = mesityl.)

  20. Effect of Transition Metal Substitution on the Structure and Properties of a Clathrate-Like Compound Eu7Cu44As23

    Directory of Open Access Journals (Sweden)

    Igor V. Plokhikh

    2016-07-01

    Full Text Available A series of substitutional solid solutions—Eu7Cu44−xTxAs23 (T = Fe, Co, Ni—based on a recently discovered clathrate-like compound (Eu7Cu44As23 were synthesized from the elements at 800 °C. Almost up to 50% of Cu can be substituted by Ni, resulting in a linear decrease of the cubic unit cell parameter from a = 16.6707(1 Å for the ternary compound to a = 16.3719(1 Å for the sample with the nominal composition Eu7Cu24Ni20As23. In contrast, Co and Fe can only substitute less than 20% of Cu. Crystal structures of six samples of different composition were refined from powder diffraction data. Despite very small differences in scattering powers of Cu, Ni, Co, and Fe, we were able to propose a reasonable model of dopant distribution over copper sites based on the trends in interatomic distances as well as on Mössbauer spectra for the iron-substituted compound Eu7Cu36Fe8As23. Ni doping increases the Curie temperature to 25 K with respect to the parent compound, which is ferromagnetically ordered below 17.5 K, whereas Fe doping suppresses the ferromagnetic ordering in the Eu sublattice.

  1. Mild hydrothermal synthesis, crystal structure, thermal behaviour, spectroscopic and magnetic properties of (NH4)0.80Li0.20[Fe(AsO4)F

    International Nuclear Information System (INIS)

    Berrocal, Teresa; Mesa, Jose L.; Larrea, Edurne S.; Bazan, Begona; Pizarro, Jose L.; Lezama, Luis; Rojo, Teofilo; Arriortua, Maria I.

    2011-01-01

    The (NH 4 ) 0.80 Li 0.20 [Fe(AsO 4 )F] compound has been synthesized under mild hydrothermal conditions. The compound crystallize in the orthorhombic Pna2 1 space group, with cell parameters a=13.352(9), b=6.7049(9), c=10.943(2) A and Z=8. The compound belongs to the KTiO(PO 4 ) structure type, with chains alternating FeO 4 F 2 octahedra and AsO 4 tetrahedra, respectively, running along the 'a' and 'b' crystallographic axes. The diffuse reflectance spectrum in the visible region shows the forbidden electronic transitions characteristic of the Fe(III) d 5 -high spin cation in slightly distorted octahedral geometry. The Moessbauer spectrum at room temperature is characteristic of iron (III) cations. The ESR spectra, carried out from room temperature to 200 K, remain isotropic with variation in temperature; the g-value being 1.99(1). Magnetic measurements indicate the predominance of strong antiferromagnetic interactions. - Graphical Abstract: Three-dimensional structure of (NH 4 ) 0.80 Li 0.20 [Fe(AsO 4 )F], a fluoroarsenate containing lithium and ammonium in the structural cavities. Highlights: → (NH 4 ) 0.80 Li 0.20 [Fe(AsO 4 )F] has been synthesized by mild hydrothermal technique. → The compound exhibits a three-dimensional structure. → Moessbauer spectrum indicates the existence of Fe(III) cations. → Visible spectroscopy confirms the hexacoordination of Fe(III). → Magnetic measurements indicate the existence of a global antiferromagnetic ordering.

  2. Metamorphoses of electronic structure of FeSe-based superconductors (Review Article)

    International Nuclear Information System (INIS)

    Pustovit, Yu.V.; Kordyuk, A.A.

    2016-01-01

    The electronic structure of FeSe, the simplest iron-based superconductor (Fe-SC), conceals a potential of dramatic increase of Tc that realizes under pressure or in a single layer film. This is also the system where nematicity, the phenomenon of a keen current interest, is most easy to study since it is not accompanied by the antiferromagnetic transition like in all other Fe-SC. Here we overview recent experimental data on electronic structure of FeSe-based superconductors: isovalently doped crystals, intercalates, and single layer films, trying to clarify its topology and possible relation of this topology to superconductivity. We argue that the marked differences between the experimental and calculated band structures for all FeSe compounds can be described by a hoping selective renormalization model for a spin/orbital correlated state that may naturally ex-plain both the evolution of the band structure with temperature and nematicity.

  3. Structural, thermal, and magnetic study of solvation processes in spin-crossover [Fe(bpp)(2)][Cr(L)(ox)(2)](2).nH(2)O complexes.

    Science.gov (United States)

    Clemente-León, Miguel; Coronado, Eugenio; Giménez-López, M Carmen; Romero, Francisco M

    2007-12-24

    The influence of lattice water in the magnetic properties of spin-crossover [Fe(bpp)2]X2.nH2O salts [bpp = 2,6-bis(pyrazol-3-yl)pyridine] is well-documented. In most cases, it stabilizes the low-spin state compared to the anhydrous compound. In other cases, it is rather the contrary. Unraveling this mystery implies the study of the microscopic changes that accompany the loss of water. This might be difficult from an experimental point of view. Our strategy is to focus on some salts that undergo a nonreversible dehydration-hydration process without loss of crystallinity. By comparison of the structural and magnetic properties of original and rehydrated samples, several rules concerning the role of water at the microscopic level can be deduced. This paper reports on the crystal structure, thermal studies, and magnetic properties of [Fe(bpp)2][Cr(bpy)(ox)2]2.2H2O (1), [Fe(bpp)2][Cr(phen)(ox)2]2.0.5H2O.0.5MeOH (2), and [Fe(bpp)2][Cr(phen)(ox)2]2.5.5H2O.2.5MeOH (3). Salt 1 contains both high-spin (HS) and low-spin (LS) Fe2+ cations in a 1:1 ratio. Dehydration yields the anhydrous spin-crossover compound with T1/2 downward arrow = 353 K and T1/2 upward arrow = 369 K. Rehydration affords the dihydrate [Fe(bpp)2][Cr(bpy)(ox)2]2.2H2O (1r) with 100% HS Fe2+ sites. Salt 2 also contains both HS and LS Fe2+ cations in a 1:1 ratio. Dehydration yields the anhydrous spin-crossover compound with T1/2 downward arrow = 343 K and T1/2 upward arrow = 348 K. Rehydration affords [Fe(bpp)2][Cr(phen)(ox)2]2.0.5H2O (2r) with 72% Fe2+ sites in the LS configuration. The structural, magnetic, and thermal properties of these rehydrated compounds 1r and 2r are also discussed. Finally, 1 has been dehydrated and resolvated with MeOH to give [Fe(bpp)2][Cr(bpy)(ox)2]2.MeOH (1s) with 33% HS Fe2+ sites. The influence of the guest solvent in the Fe2+ spin state can anticipate the future applications of these compounds in solvent sensing.

  4. New thermodynamic measurements in the U-fe system

    Energy Technology Data Exchange (ETDEWEB)

    Labroche, D.; Dugne, O. [CEA Vallee du Rhone, Dept. de Technologie de l' Enrichissement, 26 - Pierrelatte (France); Rogez, J. [CTM, 13 - Marseille (France)

    2001-07-01

    The U-Fe phase diagram data from thermal measurements by Gordon, Grogan, Chapman and Michaud and from mass spectroscopic measurements by Gardie are generally in agreement. Two line compounds UFe{sub 2} and U{sub 6}Fe exist. The enthalpy of formation of UFe{sub 2} at 298 K is reported to be -32.4 kJ/mol by Akhachinskij, -61.8 kJ/mol by Kanno and -42.03 kJ/mol by Antony. This disagreement between the different authors requires some new measurements in order to improve the knowledge of this system. Moreover no data exists on the enthalpy of formation of U{sub 6}Fe and on the heat capacity of these two materials. The objective of this study is to measure these missing data in view of performing an assessment of the phase diagram. (author)

  5. Spin-Lattice Coupling and Superconductivity in Fe Pnictides

    Directory of Open Access Journals (Sweden)

    T. Egami

    2010-01-01

    Full Text Available We consider strong spin-lattice and spin-phonon coupling in iron pnictides and discuss its implications on superconductivity. Strong magneto-volume effect in iron compounds has long been known as the Invar effect. Fe pnictides also exhibit this effect, reflected in particular on the dependence of the magnetic moment on the atomic volume of Fe defined by the positions of the nearest neighbor atoms. Through the phenomenological Landau theory, developed on the basis of the calculations by the density functional theory (DFT and the experimental results, we quantify the strength of the spin-lattice interaction as it relates to the Stoner criterion for the onset of magnetism. We suggest that the coupling between electrons and phonons through the spin channel may be sufficiently strong to be an important part of the superconductivity mechanism in Fe pnictides.

  6. Investigation of passivity and its breakdown on Fe3Al–Si and Fe3Al–Ge intermetallics in chloride-containing solution

    International Nuclear Information System (INIS)

    Rosalbino, F.; Carlini, R.; Parodi, R.; Zanicchi, G.; Scavino, G.

    2014-01-01

    Highlights: • Passivity and its breakdown on Fe 3 Al–Si and Fe 3 Al–Ge iron aluminides was investigated. • Investigation was performed in borate buffer solution with and without 100 mM KCl. • Polarization, potentiostatic transients and impedance measurements have been employed. • Results have been compared with those obtained on Fe 3 Al intermetallic. • Si and Ge improve the resistance to localized corrosion of Fe 3 Al. - Abstract: The passivity and passivity breakdown of Fe 3 Al–Si and Fe 3 Al–Ge iron aluminides were studied in borate buffer solution (pH 8.4) in the absence and presence of 100 mM KCl, performing potentiodynamic polarization, potentiostatic transients and electrochemical impedance spectroscopy (EIS) measurements complemented with scanning electron microscopy (SEM). In the absence of chloride ions Si and Ge exercise a beneficial role in the passivating characteristics of Fe 3 Al intermetallic. Addition of Si or Ge significantly modifies the electrochemical response of iron aluminide Fe 3 Al resulting in a more stable passive film. In the presence of chloride ions all the intermetallic compounds experience localized corrosion (pitting). However, Si and Ge alloying additions increase the breakdown potential and the extent of passivation domain, indicating improved resistance to initiation of pitting corrosion. Furthermore, EIS measurements performed at the breakdown state evidenced higher R ct and lower depression angle values for Fe 3 Al–Si and Fe 3 Al–Ge iron aluminides compared to Fe 3 Al intermetallic, confirming their better localized corrosion behavior. The improved resistance to pitting corrosion results from the enhanced protective function of passive film due to the presence of Si or Ge that inhibit pit initiation by hindering the adsorption of Cl − ions at the metal surface

  7. Intermetallic compound development for the 21st century

    International Nuclear Information System (INIS)

    Munroe, P.R.

    2000-01-01

    lntermetallic compounds have been vigorously researched for the past twenty years. As a result of these studies the fundamental behaviour of a number of transition metal aluminides and suicides is now well understood, and a number of alloys with commercially acceptable properties have been developed. Future challenges for these alloys, for example Ni 3 AI, TiAI and Fe 3 AI, are focused on the development of large-scale production routes. However, there remain a number of other intermetallic compounds, such as Laves phases, which exhibit some promising properties, but little is presently known about their intrinsic behaviour. For compounds such as these more fundamental studies are required

  8. Effect of Pretreatment with Sulfuric Acid on Catalytic Hydrocracking of Fe/AC Catalysts

    Directory of Open Access Journals (Sweden)

    Ruiyu Wang

    2017-01-01

    Full Text Available Activated carbon (AC was modified by H2SO4 and used as a support for catalyst. The Fe2S3/AC-T catalyst was prepared by deposition-precipitation method and used to catalyze hydrocracking of coal-related model compound, di(1-naphthylmethane (DNM. The properties of catalyst were studied by N2 adsorption-desorption, X-ray diffraction, and scanning electron microscopy. The result showed that ferric sulfate and acidic centers had synergetic effect on hydrocracking of DNM when using Fe2S3/AC-T as catalyst, the optimal loading of Fe is 9 wt.%. Hydroconversion of the extraction residue from Guizhou bituminous coal was also studied using Fe2S3/AC-T as the catalyst. The reaction was conducted in cyclohexane under 0.8 Mpa of initial hydrogen pressure at 310°C. The reaction mixture was extracted with petroleum ether and analyzed by GC/MS. Amounts of organic compounds which fall into the categories of homologues of benzene and naphthalene were detected. It suggested that the catalyst could effectively catalyze the cleavage of C-C-bridged bonds.

  9. {1-[(3,5-Dimethyl-4H-1,2,4-triazol-4-ylimino]ethyl}ferrocene

    Directory of Open Access Journals (Sweden)

    Mao-Ping Song

    2008-10-01

    Full Text Available In the title compound, [Fe(C5H5(C11H13N4], the triazolyl and Cp ring form a dihedral angle of 76.6 (3°. In the crystal structure, there are both intra- and intermolecular C—H...π interactions, forming a one-dimensional chain structure along [010].

  10. Interactions among magnetic moments in the double perovskites Sr2Fe1+xMo1−xO6

    International Nuclear Information System (INIS)

    Pilo, J.; Carvajal, E.; Oviedo-Roa, R.; Cruz-Irisson, M.; Navarro, O.

    2014-01-01

    It is well known that every double perovskite shows a characteristic magnetic behavior, as a consequence of the interactions among the magnetic moments associated with the atoms in their cells; at the same time, the electric and magnetic properties of the bulk double perovskite Sr 2 FeMoO 6 are well characterized. In this work we studied the iron rich compounds Sr 2 Fe 1+x Mo 1−x O 6 , using a supercell to model such concentrations that made Fe richer perovskites by ±66.6% and ±200%. Starting from the stoichiometric double perovskite, and modifying the Fe/Mo ratio in the compound, the study of these materials were based on the calculation of the magnetic moment at each atom, as well as the partial density of states

  11. Synthesis and crystal structure of new K and Rb selenido/tellurido ferrate cluster compounds

    Energy Technology Data Exchange (ETDEWEB)

    Stueble, Pirmin; Berroth, Angela; Roehr, Caroline [Freiburg Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2016-08-01

    In the course of a systematic study of alkali iron chalcogenido salts containing clusters [Fe{sub 4}Q{sub 8}] a series of new mixed-valent potassium and rubidium selenido and tellurido ferrates(II/III) was synthesized by carefully heating the pure elements enclosed in sample tubes under an argon atmosphere up to maximum temperatures of 800-900 C. Their crystal structures have been determined by means of single crystal X-ray diffraction. The mixed-valent Fe{sup II/III} tellurido ferrates A{sub 7}[Fe{sub 4}Te{sub 8}] form three different structure types. All structures contain tetramers of four edge sharing [FeTe{sub 4}] tetrahedra, which are connected by common edges to form only slightly distorted tetrahedral [Fe{sub 4}Te{sub 8}]{sup 7-} anions ('stella quadrangula') with a [Fe{sub 4}Te{sub 4}] cubane core. In all cases, these anions are surrounded by 26 alkali cations, which are located at the eight corners and the midpoints of the six faces and 12 edges of a cube. The three crystal structures can thus be described by three different packings of cuboid moieties: The monoclinic rubidium compound Rb{sub 7}[Fe{sub 4}Te{sub 8}] (space group C2/c, a = 2000.16(7), b = 897.79(3), c = 1768.12(6) pm, β = 117.4995(10) , Z = 4, R1 = 0.0296) is isotypic to the known cesium tellurido and sulfido ferrates Cs{sub 7}[Fe{sub 4}(S/Te){sub 8}]. Depending on the temperature, K{sub 7}[Fe{sub 4}Te{sub 8}] forms two different but closely related new structure types: The tetragonal r.t. modification (space group P4{sub 2}/nmc, a = 1222.25(14), c = 872.1(2) pm, Z = 2, R1 = 0.0583) crystallizes in a supergroup of the orthorhombic l.t. (100 K) form (space group Pbcn, a = 1715.5, b = 866.76(3), c = 1715.50(7) pm, Z = 4, R1 = 0.0160). In all structures, the cluster centered cubes are stacked to form columns along the short (∼ 870 pm) axis. These columns are themselves densely packed with 4 (both K compounds) and 6 (A = Rb) adjacent face-sharing columns. According to these

  12. Formulating the Right Title for a Research Article.

    Science.gov (United States)

    Bavdekar, Sandeep B

    2016-02-01

    Title is an important part of the article. It condenses article content in a few words and captures readers' attention. A good title for a research article is the one which, on its own, is able to introduce the research work to the fullest extent, but in a concise manner. Writing scientific titles that are informative and attractive is a challenging task. This communication describes the importance of titles and the methods of creating appropriate titles for research papers. © Journal of the Association of Physicians of India 2011.

  13. Novel La(Fe,Si){sub 13}/Cu composites for magnetic cooling

    Energy Technology Data Exchange (ETDEWEB)

    Lyubina, Julia; Hannemann, Ullrich; Ryan, Mary P. [Department of Materials, Imperial College London, London, SW7 2AZ (United Kingdom); Cohen, Lesley F. [Department of Physics, Imperial College London, London, SW7 2AZ (United Kingdom)

    2012-11-15

    An approach to engineering magnetic refrigerant materials with defined thermal transport properties is demonstrated using the example of high magnetocaloric performance La-Fe-Si alloys. A tunability of up to 300% of the thermal conductivity can be achieved in composites consisting of a La(Fe,Si){sub 13} compound and Cu prepared by electroless copper plating without compromising the magnitude of the magnetocaloric effect. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. A Fe(II)/citrate/UV/PMS process for carbamazepine degradation at a very low Fe(II)/PMS ratio and neutral pH: The mechanisms.

    Science.gov (United States)

    Ling, Li; Zhang, Dapeng; Fan, Chihhao; Shang, Chii

    2017-11-01

    A novel Fe(II)/citrate/UV/PMS process for degrading a model micropollutant, carbamazepine (CBZ), at a low Fe(II)/PMS ratio and neutral pH has been proposed in this study, and the mechanisms of radical generation in the system was explored. With a UV dose of 302.4 mJ/cm 2 , an initial pH of 7, and CBZ, PMS, Fe(II) and citrate at initial concentrations of 10, 100, 12 and 26 μM, respectively, the CBZ degradation efficiency reached 71% in 20 min in the Fe(II)/citrate/UV/PMS process, which was 4.7 times higher than that in either the citrate/UV/PMS or Fe(II)/citrate/PMS process. The enhanced CBZ degradation in the Fe(II)/citrate/UV/PMS process was mainly attributed to the continuous activation of PMS by the UV-catalyzed regenerated Fe(II) from a Fe(III)-citrate complex, [Fe 3 O(cit) 3 H 3 ] 2- , which not only maintained Fe(III) soluble at neutral pH, but also increased 6.6 and 2.6 times of its molar absorbance and quantum yield as compared to those of ionic Fe(III), respectively. In the Fe(II)/citrate/UV/PMS process, the SO 4 •- produced from the fast reaction between PMS and the initially-added Fe(II) contributed 11% of CBZ degradation. The PMS activation by the UV radiation and regenerated Fe(II) contributed additional 14% and 46% of CBZ removal, respectively. The low iron and citrate doses and the fast radical generation at neutral pH make the Fe(II)/citrate/UV/PMS process suitable for degrading recalcitrant organic compounds in potable water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Solid state structural investigations of the bis(chalcone) compound with single crystal X-ray crystallography, DFT, gamma-ray spectroscopy and chemical spectroscopy methods

    Science.gov (United States)

    Yakalı, Gül; Biçer, Abdullah; Eke, Canel; Cin, Günseli Turgut

    2018-04-01

    A bis(chalcone), (2E,6E)-2,6-bis((E)-3phenylallidene)cyclohexanone, was characterized by 1H NMR, 13C NMR, FTIR, UV-Vis spectroscopy, gamma-ray spectroscopy and single crystal X- ray structural analysis. The optimized molecular structure of the compound is calculated using DFT/B3LYP with 6-31G (d,p) level. The calculated geometrical parameters are in good agreement with the experimental data obtained from our reported X-ray structure. The powder and single crystal compounds were gama-irradiated using clinical electron linear accelerator and 60Co gamma-ray source, respectively. Spectral studies (1H NMR, 13C NMR, FTIR and UV-Vis) of powder chalcone compound were also investigated before and after irradiation. Depending on the irradiation notable changes were observed in spectral features powder sample. Single crystal X-ray diffraction investigation shows that both unirradiated and irradiated single crystal samples crystallizes in a orthorhombic crystal system in the centrosymmetric space group Pbcn and exhibits an C-H..O intramolecular and intermolecular hydrogen bonds. The crystal packing is stabilised by strong intermolecular bifurcate C-H..O hydrogen bonds and π…π stacking interactions. The asymmetric unit of the title compound contains one-half of a molecule. The other half of the molecule is generated with (1-x,y,-3/2-z) symmetry operator. The molecule is almost planar due to having π conjugated system of chalcones. However, irradiated single crystal compound showed significant changes lattice parameters, crystal volume and density. According to results of gamma-ray spectroscopy, radioactive elements of powder compound which are 123Sb(n,g),124Sb,57Fe(g,p),56Mn, 55Mn(g,n), and 54Mn were determined using photoactivation analysis. However, the most intensive gamma-ray energy signals are 124Sb.

  16. Ferric chloride-graphite intercalation compounds as anode materials for Li-ion batteries.

    Science.gov (United States)

    Wang, Lili; Zhu, Yongchun; Guo, Cong; Zhu, Xiaobo; Liang, Jianwen; Qian, Yitai

    2014-01-01

    Ferric chloride-graphite intercalation compounds (FeCl3 -GICs) with stage 1 and stage 2 structures were synthesized by reacting FeCl3 and expanded graphite (EG) in air in a stainless-steel autoclave. As rechargeable Li-ion batteries, these FeCl3 -GICs exhibit high capacity, excellent cycling stability, and superior rate capability, which could be attributed to their unique intercalation features. This work may enable new possibilities for the fabrication of Li-ion batteries. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Growth and microstructure of iron nitride layers and pore formation in {epsilon}-Fe{sub 3}N

    Energy Technology Data Exchange (ETDEWEB)

    Middendorf, C.; Mader, W. [Univ. Bonn, Inst. fuer Anorganische Chemie, Bonn (Germany)

    2003-03-01

    Layers of {epsilon}-Fe{sub 3}N and {gamma}'-Fe{sub 4}N on ferrite were produced by nitriding iron single crystals or rolled sheets of iron in flowing ammonia at 520 C. The nitride layers were characterised using X-ray diffraction, light microscopy as well as scanning and transmission electron microscopy. The compound layer consists of {epsilon}-Fe{sub 3}N at the surface and of {gamma}'-Fe{sub 4}N facing the ferrite. After 4 h of nitriding, pores develop in the near surface region of {epsilon}-Fe{sub 3}N showing more or less open porosity. Growth of the entire compound layer as well as of the massive and the porous {epsilon}-Fe{sub 3}N sublayer is diffusion-controlled and follows a parabolic growth rate. The {gamma}'-Fe{sub 4}N layer is formed as a transition phase within a narrow interval of nitrogen activity, and it shows little growth in thickness. The transformation of {gamma}'-Fe{sub 4}N to {epsilon}-Fe{sub 3}N is topotactic, where the orientation of the closed-packed iron layers of the crystal structures is preserved. Determination of lattice plane spacings was possible by X-ray diffraction, and this was correlated to the nitrogen content of {epsilon}-Fe{sub 3}N. While the porous layer exhibits an enhanced nitrogen content corresponding to the chemical composition Fe{sub 3}N{sub 1.1}, the massive e Fe{sub 3}N layer corresponds to Fe{sub 3}N{sub 1.0}. The pore formation in {epsilon}-Fe{sub 3}N{sub 1.1} is concluded to be the result of excess nitrogen atoms on non-structural sites, which have a high mobility. Therefore, recombination of excess nitrogen to molecular N{sub 2} at lattice defects is preferred in {epsilon}-Fe{sub 3}N with high nitrogen content compared to stoichiometric {epsilon}-Fe{sub 3}N{sub 1.0} with nitrogen on only structural sites. (orig.)

  18. Specific features of spin-variable properties of [Fe(acen)pic2]BPh4 · nH2O

    Science.gov (United States)

    Ivanova, T. A.; Ovchinnikov, I. V.; Gil'mutdinov, I. F.; Mingalieva, L. V.; Turanova, O. A.; Ivanova, G. I.

    2016-02-01

    The [Fe(acen)pic2]BPh4 · nH2O compound has been synthesized and studied in the temperature interval of 5-300 K by the methods of EPR and magnetic susceptibility. The existence of ferromagnetic interactions between Fe(III) complexes in this compound has been revealed, in contrast to unhydrated [Fe(acen)pic2]BPh4. The reduction in the integrated intensity of the magnetic resonance signal as the temperature decreases below 80 K has been explained by the transition of high-spin ions to the low-spin state. It has been shown that the phase transition temperature in the presence of intermolecular (ferromagnetic) interactions is lower than that in the case of noninteracting centers.

  19. Rational synthesis of high nuclearity Mo/Fe/S clusters: the reductive coupling approach in the convenient synthesis of (Cl(4)-cat)(2)Mo(2)Fe(6)S(8)(PR(3))(6) [R = Et, (n)Pr, (n)Bu] and the new [(Cl(4)-cat)(2)Mo(2)Fe(2)S(3)O(PEt(3))(3)Cl]-1/2(Fe(PEt(3))(2)(MeCN)(4)) and (Cl(4)-cat)(2)Mo(2)Fe(3)S(5)(PEt(3))(5) clusters.

    Science.gov (United States)

    Han, J; Koutmos, M; Ahmad, S A; Coucouvanis, D

    2001-11-05

    A general method for the synthesis of high nuclearity Mo/Fe/S clusters is presented and involves the reductive coupling of the (Et(4)N)(2)[(Cl(4)-cat)MoOFeS(2)Cl(2)] (I) and (Et(4)N)(2)[Fe(2)S(2)Cl(4)] (II) clusters. The reaction of I and II with Fe(PR(3))(2)Cl(2) or sodium salts of noncoordinating anions such as NaPF(6) or NaBPh(4) in the presence of PR(3) (R = Et, (n)Pr, or (n)Bu) affords (Cl(4)-cat)(2)Mo(2)Fe(6)S(8)(PR(3))(6) [R = Et (IIIa), (n)Pr (IIIb), (n)Bu (IIIc)], Fe(6)S(6)(PEt(3))(4)Cl(2) (IV) and (PF(6))[Fe(6)S(8)(P(n)Pr(3))(6)] (V) as byproducts. The isolation of (Et(4)N)[Fe(PEt(3))Cl(3)] (VI), NaCl, and SPEt(3) supports a reductive coupling mechanism. Cluster IV and V also have been synthesized by the reductive self-coupling of compound II. The reductive coupling reaction between I and II by PEt(3) and NaPF(6) in a 1:1 ratio produces the (Et(4)N)(2)[(Cl(4)-cat)Mo(L)Fe(3)S(4)Cl(3)] clusters [L = MeCN (VIIa), THF (VIIb)]. The hitherto unknown [(Cl(4)-cat)(2)Mo(2)Fe(2)S(3)O(PEt(3))(3)Cl](+) cluster (VIII) has been isolated as the 2:1 salt of the (Fe(PEt(3))(2)(MeCN)(4))(2+) cation after the reductive self-coupling reaction of I in the presence of Fe(PEt(3))(2)Cl(2). Cluster VIII crystallizes in the monoclinic space group P2(1)/c with a = 11.098(3) A, b = 22.827(6) A, c = 25.855(6) A, beta = 91.680(4) degrees, and Z = 4. The formal oxidation states of metal atoms in VIII have been assigned as Mo(III), Mo(IV), Fe(II), and Fe(III) on the basis of zero-field Mössbauer spectra. The Fe(PEt(3))(2)(MeCN)(4) cation of VIII is also synthesized independently, isolated as the BPh(4)(-) salt (IX), and has been structurally characterized. The reductive coupling of compound I also affords in low yield the new (Cl(4)-cat)(2)Mo(2)Fe(3)S(5)(PEt(3))(5) cluster (X) as a byproduct. Cluster X crystallizes in the monoclinic space group P2(1)/n with a = 14.811(3) A, b = 22.188(4) A, c = 21.864(4) A, beta = 100.124(3) degrees, and Z = 4 and the structure shows very short Mo-Fe

  20. Density and atomic volume in liquid Al-Fe and Al-Ni binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Plevachuk, Yu. [Ivan Franko National Univ., Lviv (Ukraine). Dept. of Metal Physics; Egry, I.; Brillo, J.; Holland-Moritz, D. [Deutsches Zentrum fuer Luft- und Raumfahrt, Koeln (Germany). Inst. fuer Raumsimulation; Kaban, I. [Chemnitz Univ. of Technolgy (Germany). Inst. of Physics

    2007-02-15

    The density of liquid Al-Fe and Al-Ni binary alloys have been determined over a wide temperature range by a noncontact technique combining electromagnetic levitation and optical dilatometry. The temperature and composition dependences of the density are analysed. A negative excess volume correlates with the negative enthalpy of mixing, compound forming ability and chemical short-range ordering in liquid Al-Fe and Al-Ni alloys. (orig.)